Tektronix 82-DOS Instruction Manual

Model 82-DOS Simultaneous C-V

Instruction Manual

A GREATER MEASURE OF CONFIDENCE

WARRANTY

Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1 year
from date of shipment.

Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable
batteries, diskettes, and documentation.

During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.

To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in Cleveland, Ohio.
You will be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service
facility. Repairs will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for
the balance of the original warranty period, or at least 90 days.

LIMITATION OF WARRANTY

This warranty does not apply to defects resulting from product modification without Keithley’s express written consent, or
misuse of any product or part. This warranty also does not apply to fuses, software, non-rechargeable batteries, damage from
battery leakage, or problems arising from normal wear or failure to follow instructions.

THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY
IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PRO­VIDED HEREIN ARE BUYER’S SOLE AND EXCLUSIVE REMEDIES.

NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT,
INDIRECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS
INSTRUMENTS AND SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE
OF THE POSSIBILITY OF SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIM­ITED TO: COSTS OF REMOVAL AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY
PERSON, OR DAMAGE TO PROPERTY.

Keithley Instruments, Inc. 28775 Aurora Road • Cleveland, Ohio 44139 • 440-248-0400 • Fax: [phone]

1-888-KEITHLEY (534-8453) • www.keithley.com

Sales Offices: BELGIUM: Bergensesteenweg 709 • B-1600 Sint-Pieters-Leeuw • 02-363 00 40 • Fax: [phone]

CHINA: Yuan Chen Xin Building, Room 705 • 12 Yumin Road, Dewai, Madian • Beijing 100029 • 8610-8225-1886 • Fax: [phone]
FINLAND: Tietäjäntie 2 • 02130 Espoo • Phone: [phone] • Fax: [phone]
FRANCE: 3, allée des Garays • 91127 Palaiseau Cédex • 01-64 53 20 20 • Fax: [phone]
GERMANY: Landsberger Strasse 65 • 82110 Germering • 089/84 93 07-40 • Fax: [phone]
GREAT BRITAIN: Unit 2 Commerce Park, Brunel Road • Theale • Berkshire RG7 4AB • 0118 929 7500 • Fax: [phone]
INDIA: 1/5 Eagles Street • Langford Town • Bangalore 560 025 • 080 212 8027 • Fax: [phone]
ITALY: Viale San Gimignano, 38 • 20146 Milano • 02-48 39 16 01 • Fax: [phone]
JAPAN: New Pier Takeshiba North Tower 13F • 11-1, Kaigan 1-chome • Minato-ku, Tokyo 105-0022 • 81-3-5733-7555 • Fax: [phone]
KOREA: 2FL., URI Building • 2-14 Yangjae-Dong • Seocho-Gu, Seoul 137-888 • 82-2-574-7778 • Fax: [phone]
NETHERLANDS: Postbus 559 • 4200 AN Gorinchem • 0183-635333 • Fax: [phone]
SWEDEN: c/o Regus Business Centre • Frosundaviks Allé 15, 4tr • 169 70 Solna • 08-509 04 600 • Fax: [phone]
TAIWAN: 13F-3, No. 6, Lane 99, Pu-Ding Road • Hsinchu, Taiwan, R.O.C. • 886-3-572-9077 • Fax: [phone]

2/03

Model 82-DOS Simultaneous C-V

Instruction Manual

0 1988, Keithley Instruments, Inc.

Test Instrumentation Group

All rights reserved.

Cleveland, Ohio, U.S.A.

May 1988, Fourth Printing

Document Number: 5957-901-01 Rev. D

All Keithley product names are trademarks or registered trademarks of Keitbley Inshuments. Inc.
Other brand and product names are trademarks or registered trademarks of their respective holders.

Safety Precautions

The following safety precautions should be observed before using
this product and any associated instrumentation. Although some in­struments and accessories would normally be used with non-haz­ardous voltages, there are situations where hazardous conditions
may be present.

This product is intended for use by qualified personnel who recog­nize shock hazards and are familiar with the safety precautions re­quired to avoid possible injury. Read and follow all installation,
operation, and maintenance information carefully before using the
product. Refer to the manual for complete product specifications.

If the product is used in a manner not specified, the protection pro­vided by the product may be impaired.

The types of product users are:

Responsible body is the individual or group responsible for the use

and maintenance of equipment, for ensuring that the equipment is
operated within its specifications and operating limits, and for en­suring that operators are adequately trained.

Operators use the product for its intended function. They must be

trained in electrical safety procedures and proper use of the instru­ment. They must be protected from electric shock and contact with
hazardous live circuits.

Maintenance personnel perform routine procedures on the product

to keep it operating properly, for example, setting the line voltage
or replacing consumable materials. Maintenance procedures are de­scribed in the manual. The procedures explicitly state if the operator
may perform them. Otherwise, they should be performed only by
service personnel.

Service personnel are trained to work on live circuits, and perform

safe installations and repairs of products. Only properly trained ser­vice personnel may perform installation and service procedures.

Keithley products are designed for use with electrical signals that
are rated Installation Category I and Installation Category II, as de­scribed in the International Electrotechnical Commission (IEC)
Standard IEC 60664. Most measurement, control, and data I/O sig­nals are Installation Category I and must not be directly connected
to mains voltage or to voltage sources with high transient over-volt­ages. Installation Category II connections require protection for
high transient over-voltages often associated with local AC mains
connections. Assume all measurement, control, and data I/O con­nections are for connection to Category I sources unless otherwise
marked or described in the Manual.

Exercise extreme caution when a shock hazard is present. Lethal
voltage may be present on cable connector jacks or test fixtures. The
American National Standards Institute (ANSI) states that a shock
hazard exists when voltage levels greater than 30V RMS, 42.4V
peak, or 60VDC are present. A good safety practice is to expect

that hazardous voltage is present in any unknown circuit before
measuring.

Operators of this product must be protected from electric shock at
all times. The responsible body must ensure that operators are pre­vented access and/or insulated from every connection point. In
some cases, connections must be exposed to potential human con­tact. Product operators in these circumstances must be trained to
protect themselves from the risk of electric shock. If the circuit is
capable of operating at or above 1000 volts, no conductive part of

the circuit may be exposed.

Do not connect switching cards directly to unlimited power circuits.
They are intended to be used with impedance limited sources.
NEVER connect switching cards directly to AC mains. When con­necting sources to switching cards, install protective devices to lim­it fault current and voltage to the card.

Before operating an instrument, make sure the line cord is connect­ed to a properly grounded power receptacle. Inspect the connecting
cables, test leads, and jumpers for possible wear, cracks, or breaks
before each use.

When installing equipment where access to the main power cord is
restricted, such as rack mounting, a separate main input power dis­connect device must be provided, in close proximity to the equip­ment and within easy reach of the operator.

For maximum safety, do not touch the product, test cables, or any
other instruments while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge
any capacitors before: connecting or disconnecting cables or jump­ers, installing or removing switching cards, or making internal
changes, such as installing or removing jumpers.

Do not touch any object that could provide a current path to the com­mon side of the circuit under test or power line (earth) ground. Always
make measurements with dry hands while standing on a dry, insulated
surface capable of withstanding the voltage being measured.

The instrument and accessories must be used in accordance with its
specifications and operating instructions or the safety of the equip­ment may be impaired.

Do not exceed the maximum signal levels of the instruments and ac­cessories, as defined in the specifications and operating informa­tion, and as shown on the instrument or test fixture panels, or
switching card.

When fuses are used in a product, replace with same type and rating
for continued protection against fire hazard.

Chassis connections must only be used as shield connections for
measuring circuits, NOT as safety earth ground connections.

If you are using a test fixture, keep the lid closed while power is ap­plied to the device under test. Safe operation requires the use of a
lid interlock.

5/02

If or is present, connect it to safety earth ground using the
wire recommended in the user documentation.

!

The symbol on an instrument indicates that the user should re­fer to the operating instructions located in the manual.

The symbol on an instrument shows that it can source or mea­sure 1000 volts or more, including the combined effect of normal
and common mode voltages. Use standard safety precautions to
avoid personal contact with these voltages.

The WARNING heading in a manual explains dangers that might
result in personal injury or death. Always read the associated infor­mation very carefully before performing the indicated procedure.

The CAUTION heading in a manual explains hazards that could
damage the instrument. Such damage may invalidate the warranty.

Instrumentation and accessories shall not be connected to humans.

Before performing any maintenance, disconnect the line cord and
all test cables.

To maintain protection from electric shock and fire, replacement
components in mains circuits, including the power transformer, test
leads, and input jacks, must be purchased from Keithley Instru­ments. Standard fuses, with applicable national safety approvals,
may be used if the rating and type are the same. Other components
that are not safety related may be purchased from other suppliers as
long as they are equivalent to the original component. (Note that se­lected parts should be purchased only through Keithley Instruments
to maintain accuracy and functionality of the product.) If you are
unsure about the applicability of a replacement component, call a
Keithley Instruments office for information.

To clean an instrument, use a damp cloth or mild, water based
cleaner. Clean the exterior of the instrument only. Do not apply
cleaner directly to the instrument or allow liquids to enter or spill
on the instrument. Products that consist of a circuit board with no
case or chassis (e.g., data acquisition board for installation into a
computer) should never require cleaning if handled according to in­structions. If the board becomes contaminated and operation is af­fected, the board should be returned to the factory for proper
cleaning/servicing.

MODEL 82-DOS SPECIFICATIONS

ANALYSIS CAPABILITIES
CONSTANTS:

GRAPHICS:

Measured:

Calculated:

Flatband C and V
Threshold Voltage
Bulk Doping
Effective Oxide Charge
Work Function
Doping Type
Average Doping
Best Depth

Simultaneous C vs. Gate Voltage
High Frequency C vs. Gate Voltage
Quasistatic C vs. Gate Voltage
Conductance vs. Gate Voltage
Q/t Current VS, Gate Voltage
Quasistatic C and Q/t Current vs. Delay Time
Interface Trap Density vs. Trap Energy
Doping vs. Depletion Depth
Ziegler (MC0 Doping vs. Depth
Depletion Depth vs. GateVoltage
High Frequency l/C’ vs. Gate Voltage
Band Bending vs. Gate Voltage
High Frequency C vs. Band Bending
Quasistatic C vs. Band Bending

VOLTAGE MEASUREMENT

ACCURACY (1 Year. W-‘WC): S,.O5% rdg + 5OmV).
RESOLUTION: IOmV.
TEMPERATURE COEFFICIENT W-18” & 28=40”0:

*.(0.005% + ImV)/“C.

OUASISTATIC CAPACITANCE*

TEMPERATURE COEFFICIENT W-18” & 28”-4O”C):

k(O.O2% rdg + 0.1 pW”C.

HIGH FREQUENCY CAPACITANCE*

SHUNT CAPACITANCE LOADING EFFECT: 0.1% of reading addi-

tionalerrorperlOOpFloadwithequalshuntloadoninputandoutput.
TEST VOLTAGE: 15m” m ? 10%.
TEST FREQUENCY TOLERANCE: 3.1%.

MAxIMIJM SWEEP SPAN, I v,,, - v,,, I : 40”.
MAXIMLM OUTPUT CURRENT: ztzm.4 @I%, +20%).

SWEEPSTEP”OL’TAGESELECTIONS: lOm”,2Om”,5Om”, 1OOm”.
DC OUTPDTRESISTANCE: <IOR.

GENERAL

READINGRATES: 41/2readingspersecondtoonereadingevery400

seconds.
DATA BUFFER: 1000 points maximum.
GRAPHICALO~~S:Computerdisplayordigitalplottersupport-

ininE,, with IEEE-488 interface; also “screen cop)+’ to compatible

DIGITAL UO: Consists of one output, four inputs, +5V (series limited

with 33R). and COMMON referenced to IEEE488 COMMON. Out-

put wi” drive one TI’L load. Inputs represent one TTL load.
MAXIMLM INPUT: 30V peak, DC to 6OHz sine wave.
MAXMUM COMMON MODE VOLTAGE: 30V maximum, DC to

6OHz sine wave.
OPERATING ENVIRONMENT: 0’ to 40°C 70% non-condensing RH

up to 35°C.
STORAGE ENVIRONMENT: -25” to +65”C.
WARM-w: 2 hours to rated accuracy.

Specifications subject to change without notice.

‘NOTES

MINIMUM COMPUTER CONFIGURATION:

IBM AT, FS/Z, or 100% compatible DOS 3.2 or greater
640k of memory Hard disk drive

CGA, EGA, VGA, or Hercules Graphics adapter.
IEEE-488 (GPIB) INTERFACE CARDS SUPPORTED:
Using IOtech Driver488 software “2.60 o* earlier:

CapitalEquipmentPC-488,4x488;IBMGPIBAdapter;IOtechGP488,
GP488A, GP488B+, MP488, Mp488CT Keithley PC488-CEC, 4488.
CEC-OM, 4488-CEC-1M; Metmbyte KM488DD. KM488-ROM; Na­tional INtNments PC-U, PC-UA, PC-III.

Using IOtech Driver488 software W-61:

IOtech GP48SB+, MP488, MP488CT

IOtech Personal 48812 is required for PS/2 operation.
MODEL S&DOS COMPONENTS:

Model 230-l: Programmable Voltage Source
Model 595: Quasistatic cv Meter
Model 590: IOOk/lM CV Analvzer
Model 5909: Calibration Source;
Model 5957:
Model 5951:

4801:
7007-l:
7007-2:
7051-2:

Model 82.DOS CV Software and Manual
Remote Input Coupler-Includes Models:
Low Noise BNC Cable, 1 .?m (4 ft.) (5 supplied)
Shielded IEEE488 Cable, Im (3.3 ft.) (2 supplied)
Shielded IEEE-488 Cable, 2m (6.6 ft.) (1 supplied)
RG-58C BNC to BNC Cable, 0.6m (2 ft.) 0 supplied)

MODEL 5957 SIMULTANEOUS C-V SOFTWARE

OVERVIEW
INSTRUMENTS CONTROLLED: Model 590/100k/lM C-V Analyzer,

Model 595 Quasistatic C-V Meter, Model 230-I Voltage Source.

SYSTEM ACCESSORIES SUPPORTED: Model 5951 Remote Input

Coupler (controlled through the Model 230-l) and Model 5909 Calibra­tion Capacitors.

TESTS: Controls inshuments to acquire and analyze C-V data.

Simultaneous Quasistatic and High Frequency C-V Measurement:

The K182CV program controls the Model 8%DOS system to measure
high frequency and quasistatic C-V in the same voltage sweep.

HighFrequencyC-VMeasurement: TheKL590CVprogramcan~~olsthe

Model 590/100k/lM to measue 1OOkHz or 1MHz capadtance and
conductance (or resistance) versus voltage.

Quasistatic C-V Measurement: The KI595CV program controls the

Mode1595 tomeasurequasistatiiccapacitanceandQ/t”ersus”oltage.

DATA DISPLAY: Graphic or list display of data arrays. Tabular display

of calculated parameters.

FILES:

C-V Parameter File (.PAR): Contains all selup parameters far C-V

Measurements.

Data Destination Files LDAT): Each contains C-V we data, user-

input device parameters, and derived results. Compatible with
Model 5958.

Cable Calibration File (PKGB?CAL.CAL): Contains reference capaci-

tor values and calibration constants to calibrate particular range and
frequency combinations of the Model 59D,,OOk,,M and Mode, 595.

Material Constants File (MATERIAL.CON): Specifies material con-

stants to be used in analysis such as insulator and semiconductor
permittivity, bandgap energy, inbinsic carrier concentration, metal
work function, and electron affinity

CAPACITANCE MEASUREMENT CAPABILITY:

Test Signal Frequency: Quasistatic and IOOkHz or IMHz.
Quasistatic Measurement Ranges: 200pF and 2OOOpF.
lOO!cHz Measurement Ranges: 200pF/ZO@uS, and 2nF/2mS.
IMHz Measurement Ranges: 200pF/2mS, 2nF,2OmS.
BiasVoltage: ~120VmaximumuslngMadel595intemal”oltagesource

coupled with Model 230-l external voltage source.
Bias Voltage Waveform: Stair waveform.
Selectablemeasurementfilter, quasistaticcapacitance leakage current

correction, and series or parallel device model.

CABLE CALIBRATION PROGRAM: The CABLECAL.EXE Utility con-

trolstheMadel590tocorredfor cableconnection p&effects. Themenu­driven utility stores reference capacitor values and measwed cable
cahbration parameters for the Model 590 in the PKG82CALCAL file.
DuringModel5957executio~theseparametersaresemtotheModel590
f”xn the file.

ANALYSIS
KI82CV PROGRAM:

MIS Analysis Constants: Oxide capacitance and thickness, gate area,

series resistance, equilibrium minimum capadtance, average doping,

bulk doping, bulk potential, Debye length, tlatband capacitance and
“Oltage, work function difference, threshold voltage, effective oxide
charge and charge concentration, d&ice type, best depth, and
capacitance gain and offset.

Doping Profile: Interface hap corrected depletion approximation dop

ing versus depletion depth and depth versus gate voltage, Ziegler
method Majority Carrier Corrected (MC0 doping profile.

Interface T*ap Density: Interface trap density “emus hap energy, band

bending “emus Sate voltage and capacitance versus band bending.

KI59OCVPROGRAM:

MIS Analysis Constants: Oxide capacitance and thickness, gate area,

series resistance, equilibrium minimum capacitance, average doping,
bulk doping, bulk potential, Debye length, flatband capacitance and
voltage, work function difference, threshold voltage, effective oxide
chargeandchargeconcen~ation,devicetype,bestdepth,and capaci­tance gain and offset.

Doping Profile: Depletion approximation doping versus depletion

depthanddepth”ersusgate”oltage,ZieglermethodMajorityCarrier
Corrected (MC0 doping profile.

KI595CV PROGRAM:

MISAnalysisConstants: Oxidecapacitanceandthickness,gateareaand

capacitance gain and offset.

FILEMERGEPROGRAM: TheFILF.MRG.EXEutitycombines quasistatic

C-V data from the Made, 5957V2.0 with high-frequency C-V data

from~59OCVorhomtheMode15958tocreat~eddatafile(.DAT)suitable

for analysis by both the Model 5957”2.0 and Model 5958.

SYSTEM REQUIREMENTS
RECOMMENDED COMPUTER CONFIGURATION: IBM compatible

80386with80287or80387mathcoprocessoranddiskca~e,blOkBRAM,
hard disk drive, 1.2MB 5*-inch or 720kB 3%inch floppy drive, EGA or
VGA monitor, Microsoft or Lagitech mouse.

MINIMUM COMPUTER CONFIGURATION: IBM AT. PS/2. or 100%

compatible, 64OkB RAM, hard disk drive, 1.2MB 51,~.inch or 720kB 31~.

inch “aon” drive.
OPERATING SYSTEM: M&DOS or PC-DOS3.2 (minimum).
GRAPHICS ADAPTBR:~ CGA, EGA, VGA (EGA made), or Hercules

Graphics Adapter.

MEMORY and DISK STORAGE REQUIREMENTS: 3MB of hard disk

space (prior to installation) and SOOkB free conventional RAM.

IEEE.488 (GPIB) INTERFACE CARDS SUPPORTED:

Using IOtech Driver 488 software V2.60 or earlier:

CapitalEquipmentPC-488,4x488; IBMGPIB Adapter; IOtechGP488,
GI’488A, GI’488B+, MP488, MP488a; KeithIey PC-48&CEC, 4-488.
CEC-OM, 4-488-CEC-IM: M&mbyte KM48&DD, KM488-ROM;

National Insments PC-II, PC-LIA, PC-III.

Using IOtech Driver 488 software V261:

IOtech GP488B+, MI’488, MP488CT.

IOtech Personal 48812 is required far PS/2 operation.

COMPATIBLEPmRS: CannonBJ80; C.ItohProwriter; CItah24LQ;

Epson FX, RX, MX, LQ1500; HP ThinkJet, LaserJet+; IBM Graphic or

Professional; NEC 8023,802S; NEC Pinwriter P Series; Okidata 92,93,

192+; Smith Corona DlOO; Tekhonix 4695/6; Toshiba 24 pin.

COhlPATIBLE PLOTIXRS: Epson HI-SO; Hewlett-Packard 7470,X75,

7440; Houston DMPXX; Roland DXY-800; Watanabe Dig&plot.

COMPATIBLE MOUSE: Microsoft or Lo@tech mouse with MOUSE.SYS

installed.

MATERIALS PROVIDED:

I”stNcti0” manual.
Diskettes containing installation, programs, source code, and sample

data.

*Note: Microsoft BASIC 7.1 required to modify source code.

Specifications subject to change without notice.

Table of Contents

SECTION 1

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.7.1

1.7.2

1.8

1.9

1.9.1

1.9.2

1.9.3

1.9.4

1.9.5

1.10

1.11

1.11.1

1.11.2

1.11.3

INTRODUCTION ...................

FEATURES..
WARRANTY INFORMATION

MANUAL ADDENDA ...............

sAFETYsYMBoLsANDTERMs .......

SPECIFICATIONS ..................

UNPACKING AND INSPECTION ......

Unpacking Procedure

Supplied Equipment

REPACKING FOR SHIPMENT .........

COMPUTER REQUIREMENTS ........

Computer Hardware Requirements ....

Supported Graphics Card ...........

Supported IEEE488 Interfaces .......

Recommended Printers and Plotters ...

System Software Requirements

SERVICE AND CALIBRATION
OPTIONAL ACCESSORIES

Connecting Cables

Rack Mount Kits

Software utilities

- General Information

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..............

...............

.........

l-l
l-l
l-2
1-2
1-2
l-2
l-2
l-2

1-2
l-3
l-3
l-3
l-3
l-3
14
14
l-5
l-5
l-5
l-5

l-5

SECTION 2 - Getting Started

2.1

2.2

2.2.1

2.2.2

2.2.3

2.2.4

2.2.5

2.3

2.3.1

2.3.2

2.3.3

2.3.4

2.3.5

2.3.6

2.4

2.4.1

2.4.2

2.4.3

INTRODUCTION
HARDWARE CONFIGURATION

System Block Diagram

Remote Input Coupler

System Connections

IEEE-488 Bus Connections

Remote Coupler Mounting

SYSTEM POWER UP

Instrument Power Requirements
Power Connections
Environmental Conditions .

WarmUpPeriod......................................

Power Up Procedure

LineFrequency.......................................

COMPUTER HARDWARE AND SOFTWARE INSTALLATION

Interface Card Installation

Softwarebackup ,,..._........_...._.......,..........

Memory and Hard Disk Considerations

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....... 2-1

.......

.......

.......

....... 2-5

....... 2-6

.......

....... 2-8

....... 2-8

....... 2-8

....... 2-8

....... 2-8

....... 2-8

....... 2-9

.......

.......

....... 2-9

.......

2-l
2-l

2-2

2-6

2-9
2-9

2-10

2.4.4

2.4.5

2.4.6

2.4.7

2.4.8

2.4.9

2.4.10

2.5

2.5.1

2.5.2

2.5.3

2.5.4

2.5.5

2.5.6 RehmingtoDOS..

2.6 SYSTEM CHECKOUT

2.6.1

2.6.2 System Troubleshooting

Model 82 Software Installation
IEEE-488 Driver Software Installation
CONFIG.SYS Modification
lnstallationverification
Plotter and Printer Considerations
RumingtheSoftware
Default Material Constants

SOFTWAREOVERVIEW

SystemReset
System Characterization
Compensating for Series Resistance and Determining Device Parameters
Device Measurement
Data Analysis and Plotting

CheckoutProcedure

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SECTION 3 - Measurement

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2-10
2-12

...

:

2-12
2-12
2-13
2-14
2-15
2-15
2-15

2-15

2-15
2-16
2-17

2-17
2-17
2-17
2-17

3.1

3.2

3.3

3.4

3.4.1

3.4.2

3.4.3

3.4.4

3.4.5

3.5

3.5.1

3.5.2

3.5.3

3.5.4

3.5.5

3.6

3.6.1

3.6.2

3.6.3

3.6.4

3.7

3.7.1

3.7.2

3.7.3

3.7.4

3.7.5

3.7.6

3.8

3.8.1

INTRODUCTION
MEASUREMENTSEQUENCE..
SYSTEMRESET
TESTING AND CORRECT!NG FOR SYSTEM LEAKAGES AND STRAY5

TestandCorrectionMenu
ParameterSelection
ViewingLeakageLevels
System Leakage Test Sweep
OffsetSuppression

CORRECTING FOR CABLING EFFECTS

When to Perform Cable Correction

Recommendedsources
SourceConnections
CorrectionProcedure
Optimiziig Correction Accuracy to Probe Tips

CHARACTERIZING DEVICE PARAMF.TJZRS

Device Characterization Menu
Running and Analyzing a Diagnostic C-V Sweep
Detetig Series Resistance, Oxide Capacitance, Oxide Thickness, and Gate Area
Determining CMIN and Optimum Delay Time

MAKINGC-VMEASUREMENTS

C-VMeasurementMenu

Programmin g Measurement Parameters .
Selecting Optimum C-V Measurement Parameters
ManualC-VSweep
AutoC-VSweep

UsingConwtedCapacitance .................................................

LIGHTCONNECTIONS

DigitalI/OPortTerminals

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3-1
3-1
3-3
34
34
3-5
3-8
3-10
3-13
3-13
3-13
3-14
3-14
3-15
3-15
3-15
3-15
3-17
3-19
3-21
3-25
3-25
3-25
3-29
3-29
3-31
3-31
3-33
3-33

3.8.2

3.8.3

3.9

3.9.1

3.9.2

3.9.3

3.9.4

3.9.5

3.9.6

3.9.7

3.9.8

LED Connections ....................

Relay Control .......................

MEASUREMENT CONSIDERATIONS

Potential Error Sources ................

Avoiding Capacitance Errors ............

Correcting Residual Errors .............

Interpreting c-v Curves ...............

Dynamic Range Considerations ..........

Series and Parallel Model Equivalent Circuits

Device Considerations ................

Test Equipment Considerations ..........

SECTION 4 - Analysis

......

...........

...........

...........

...........

...........

...........

...........

...........

...........

...........

...........

3-33
3-33
3-35
3-35
3-37
3-38
3-38
340
341
342
3-43

4.1

4.2

4.2.1

4.2.2

4.2.3

4.3

4.3.1

4.3.2

4.4

4.4.1

4.4.2

4.4.3

4.4.4

4.5

4.5.1

4.5.2

4.5.3

4.5.4

4.5.5

4.5.6

4.5.7

4.5.8

4.5.9

4.5.10

4.5.11

4.5.12

4.6

4.6.1

4.6.2

4.6.3

4.6.4

4.6.5

4.6.6

4.6.7

INTRODUCTION
CONSTANTS AND SYMBOLS USED FOR ANALYSIS

Default Constants ..............................

Raw Data Symbols

Calculated Data Symbols ........................

OBTAINING INFORMATION FROM BASIC C-V CURVES

Basic C-V Curves ..............................

Determining Device Type ........................

ANALYZING C-V DATA ..........................

Plotter and Printer Requirements
AnalysisMenu

Saving and Recalling Data ........................

Displaying and Printing the Reading and Graphics Arrays

ANALYSIS CONSTANTS ..........................

Oxide Capacitance, Thickness, and Area Calculations

Series Resistance Calculations .....................

ChangingNsm ...............................

Changing C
Flatband Capacitance and Flatband Voltage

Threshold Voltage .............................

Metal Semiconductor Work Function Difference

Effective Oxide Charge ..........................

Effective Oxide Charge Concentration

Average Doping Concentration ....................

Best Depth ...................................

GainandOffset

GRAPHICAL ANALYSIS ..........................

Analysis Took ................................

GraphingData ................................

Reading Array ......................

Graphics Amy ......................

Graphing the Reading Array ............

Doping Profile ......................

Ziegler (MC0 Doping Profile ...........

................................

....

.............................

..................

................................

m ................................

..........

.......

...............

................................

...

4-1
4-l
4-l
4-2
4-2
4-3
4-3
44
44
44
4-5
4-5
4-6
4-10
4-12
4-12
4-14
4-14
4-14
4-14
4-15
4-15
4-16
4-16
4-16
4-17
4-17
4-17
4-18
4-19
4-20
4-20
4-26

4-30

4.6.8

4.7

4.7.1

4.7.2

4.7.3

4.8 REFERENCES AND BIBLIOGRAPHY OF C-V MEASUIUZMENTS AND RELATED TOPICS

4.8.1

4.8.2

Interface Trap Density Analysis .............................................

MOBILE IONIC CHARGE CONCENTRATION MEASUREMENT

Flatband Voltage Shift Method .............................................

Triangular Voltage Sweep Method
Using Effective Charge to Determine Mobile Ion Drift

References ............................................................

Bibliography of C-V Measurements and Related Topics

.......................................... 4-36

............................

........................... 440

.................... 4-35

SECTION 5 - Principles of Operation

4-31

4-36

440
4-40
440

5.1 INTRODUCTION

5.2

5.3 REMOTE INPUT COUPLER

5.3.1 Tuned Circuits .

5.3.2 Frequency Control

5.4 QUASISTATIC C-V

5.4.1 Quasistatic C-V Configuration

5.4.2

5.5 HIGH FREQUENCY C-V

5.5.1 High Frequency System Configuration

5.5.2 High-Frequency Measurements.

5.6

SYSTEM BLOCK DIAGRAM

Measurement Method

SIMULTANEOUS C-V

SECTION 6 - Replaceable Parts

6.1 INTRODUCTION .............................................

6.2 PARTSLIST. ................................................

6.3 ORDERING INFORMATION

6.4

6.5

FACTORYSERVICE ...........................................

COMPONENT LAYOUTS AND SCHEMATIC DIAGRAMS .............

....................................

5-l

........

........

........

........

........

........... 6-l

...........

...........

...........

........... 6-l

5-l
5-1
5-3
5-3
5-3
5-3
5-3
5-5
5-5
5-5
s-6

6-l
6-l
6-l

APPENDICES

A
B
C
D
E

F

G
H

F

Material Constants File Modification
Analysis Constants
Summary of Analysis Equations
Prefixes of unit Values
Using the Model 590 and 595 Programs
Graphic 4.0 Functions Used by Model 82-DOS

Cable Calibration Utility
File Merge Utility
Data File Format
Software Modification

List of Illustrations

SECTION 2 - Getting Started

Figure 2-l

Figure 2-2

Figure 2-3
Figure 24

Figure 2-5
Figure 2-6
Figure 2-7

Figure 2-8

System Blodc Diagram
Model 5951 Front Panel
Model 5951 Rear Panel
System Front Panel Connections
System Rear Panel Connections
System IEEE488 Connections
Remote Coupling Mounting
Main Menu

SECTION 3 - Measurement

Figure 3-l

Figure 3-2

Figure 3-3
Figure 3-4
Figure 3-5
Figure 3-6

Figure 3-7

Figure 3-8
Figure 3-9
Figure 3-10
Figure 3-11
Figure 3-12
Figure 3-13
Figure 3-14
Figure 3-15
Figure 3-16
Figure 3-17
Figure 3-18
Figure 3-19
Figure 3-20
Figure 3-21
Figure 3-22
Figure 3-23
Figure 3-24
Figure 3-25
Figure 3-26
Figure 3-27
Figure 3-28

Figure 3-29

Figure 3-30

Figure 3-31

Measurement Sequence ................................

Model 82 Main Menu ..................................

Stray Capacitance and Leakage Current Menu

Parameter Selection Menu ...............................

Save/Load Parameter Menu .............................

Monitor Leakage Menu .................................

Diagnostic Sweep Menu ................................

Leakage Due to Constant Current
Q/t Curve with Leakage Resistance
Constant Leakage Current Increases Quasistatic Capacitance
Quasistatic Capacitance with and without Leakage Current
Cable Correction Connections
Device Characterization Menu
C-V Characteristics of n-type Material
C-V Characteristics of p-type Material
Series Resistance and Oxide Capacitance
CmandDelayTimeMenu
Q/tandCavs.DelayTimeExample
Choosing Optimum Delay Time
Capacitance and Leakage Current Using Corrected Capacitance
Device Measurement and Analysis Menu

Parameter Selection Menu ...............................

Manual Sweep Menu ...........................

Auto Sweep Menu .............................

Digital I/O Port Terminal Arrangement

Direct LED Control .............................

Relay Light Control
C-V Curve with Capacitance Offset
C-V Curve with Added Noise
C-V Curve Resulting from Gain Error
Curve Tilt Cause by Voltage Dependent Leakage

.............................

...........................

..............................

..........................

............................

.....................

.........................

.......................

......................

......................

....................

.......................

...................

.............

.................

...............

............

............

............

............

............

...........

...........

...............

......

.....

......

.......

....... 2-3

.......

....... 2-5

.......

....... 2-7

.......

.......

2-2

2-4

2-6

2-7
2-16

3-2
3-3
34
3-5
3-7
3-9
3-11
3-12
3-12
3-12
3-13
3-14
3-16
3-18
3-18
3-20
3-22
3-23

3-24
3-24
3-26
3-27
3-30
3-32
3-33
3-34
3-34
3-35
3-35
3-35
3-36

Figure 3-32
Figure 3-33 Normal C-V Curve Results When Device is kept in Equilibrium
Figure 3-34
Figure 3-35 Curve Distortion when Hold Time is too Short
Figure 3-36 Series and Parallel Impedances

C-V Curve Caused by Nonlinearity

Curve Hysteresis Resulting When Sweep is too Rapid

SECTION 4 - Analysis

......... 3-36

......... 3-39

......... 3-39

......... 3-40

......... 3-41

Figure 4-1
Figure 42
Figure 4-3
Figure 4-4
Figure 4-5
Figure 4-6
Figure 4-7 Analysis Constant Display
Figure 48 G-V Curve without Series Resistance Compensation (RSERIES zlOOW)
Figure 49 G-V Curve with Series Resistance Compensation (Rsms =lOOW)
Figure 4-10
Figure 4-11 Graphics Control Menu

Figure 4-12 Quasistatic Capacitance vs. Gate Voltage Example ......................

Figure 4-13 High-Frequency vs. Gate Voltage Example ...........................

Figure 4-14
Figure 4-15 Q/t vs. Gate Voltage Example

Figure 416 Conductance vs. Gate Voltage Example
Figure 417 Depth vs. Gate Voltage Example
Figure 4-18 Doping Profile vs. Depth Example
Figure 419
Figure 4-20
Figure 4-21 Band Bending vs. Gate Voltage Example
Figure 422
Figure 4-23

Figure 424 Interface Trap Density vs. Energy from Midgap Example ................

Figure 425 Model for TVS Measurement of Oxide Charge Density ..................

C-V Characteristics of p-type Material ...............................

C-V Characteristics of n-type Material ...............................

DataAnalysisMenu..

Example of Reading Array Print Out ................................

Example of Graphics Array Print Out ...............................

Example of Ziegler (MCC) Doping Array Print Out

Simplified Model used to Determine Series Resistance

High-Frequency and Quasistatic Capacitance vs. Gate Voltage Example

1 /C’H vs. Gate Voltage Example ...................................

Ziegler Doping Profile Example ....................................

Quasistatic Capacitance vs. Band Bending Example

High-frequency Capacitance vs. Band Bending Example

..........................................

.....................

.......................................

...................

.........................................

....................................

.............................

...................................

.................................

.............................

.....................

.................

........

...........

.....

4-3
4-4

4-5
4-7
4-8
4-9
4-l 1
4-12
4-13
4-13
4-18
4-21
4-22
4-23
4-24
4-25
4-26
4-28
4-29
4-30

4-32
4-33
4-34
4-35
4-37

SECTION 5 - Principles of Operation

Figure 5-1

Figure 5-2
Figure 5-3
Figure 5-4
Figure 5-5
Figure 5-6
Figure 5-7
Figure 5-8

Model 82-DOS System Block Diagram
Simplified Schematic of Remote Input Coupler

System Configuration for Quasistatic C-V Measurements
Feedback Charge Method of Capacitance Measurements
Voltage and Charge Waveforms for Quasistatic Capacitance Measurement
System Configuration for High Frequency C-V Measurements
High Frequency Capacitance Measurement

SimultaneousC-VWavefoml ........................................

..................................

...........................

..............................

...................

....................

...............

5-2
5-2
5-3
5-4
5-4
5-5
5-6
5-7

List of Tables

SECTION l-

Table l-l
Table l-2
Table l-3
Table 14
Table l-5
Table l-6

Table l-7

General Information

Supplied Equipment
Computer Hardware Requirements
Graphics Cards Supported by Model 82-DOS
IEEE488 Interfaces Supported by Model 82-DOS
Recommended Printers
Recommended Plotters
System Software Requirements

SECTION 2 - Getting Started

Table 2-l
Table 2-2
Table 2-3
Table 24

Table 2-5

SuppliedCables ..,,,..,,........,,..._....__......,_,,........,,,,....... 2-5

Default Directories
Graphics Cards Supported by Model 82-DOS
Supported Printers and Plotters
System Troubleshooting Summary

SECTION 3 - Measurement

Table 3-l
Table 3-2
Table 3-3

Cable Correction Sources
Digital I/O Port Terminal Assignments

Converting Series-parallel Equivalent Circuits

...................................................

.........................................

....................................

.............

.............

.............

.............

.............

l-2
l-3
l-3
l-3
14
1-4
14

2-10
2-11
2-12
2-17

3-14
3-33
3-42

SECTION 4 - Analysis

Table 4-l
Table 4-2
Table 4-3

Default Material Constants

Analysis Constants
GraphicalTools

......

........................................................

..........................................................

........................

..................

4-2

4-10
4-17

SECTION 1

General Information

1.1 INTRODUCTION

This section contains overview information for the
Model82-DOSSimultaneousC-V systemandis arranged
as follows:

1.2 Features

1.3 warranty Information

1.4 Manual Addenda

1.5 Safety Symbols and Terms

1.6 Specifications

1.7 Unpacking and Inspection

1.8 Repacking for Shipment

1.9 Computer Requirements

1.10 Service and Calibration

1.11 Optional Accessories

1.2 FEATURES

Model 82-DOSis a computer-controlled system of instru­ments designed to make simultaneous quasistatic C-V
and high frequency UOOkHz and IMHz) C-V measure­ments on semiconductors. Eachsystem includes aMode
590 C-V Analyzer for high-frequency C-V measure-
ments, and a Model 595 Quasistatic C-V Meter, along
with the necessary input coupler, connecting and control

cables, and cable calibration sources. A Model 230-l Volt­age Source is also included.

Key Model 82.DOS features include:

l Remote input coupler to simplify connections to the

device under test. Both the Model 595 and the Model

590 are connected to the device under test through tlw

coupler, allowing simultaneous quasistatic and high
frequency measurement of device parameters with
negligible interaction between instruments.

. Supplied menu-driven software allows easy collection

of C, G, V, and Q/t data with a minimum of effort. No
computer programming knowledge is necessary to
operate the system.

. Data can be stored on disk for later reference or analy-

sis.

l File merge utility allows sequentially-measured

quasistatic and high-frequency C-V data to be com-

bined for later analysis.

. Graphical analysis capabilities allow plotting of data

on the computer display as well as hard copy graphs
using an external digital plotter. Graphical analysis for
such parameters as doping profile and interface trap
density vs. trap energy is provided.

l Supplied external voltage source (Model 230-l) ex-

tends the DC bias capabilities to H2OV.

. Supplied calibration capacitors to allow compensation

for cable effects that would otherwise reduce the accu­racy of 1OOkHz and 1MHz measurements.

l Allnecessarycablesaresuppliedfor easy system hook

UP.

l-1

SECTION 1
General Information

. Supplied INSTALL program simplifies software in-

stallation.

. Supplied cable calibration utility corrects for cabling

effects.

1.3 WARRANTY INFORMATION

Warranty information is located on the inside f+ont cover

of this instruction manual. Should you require warranty
service, contact your Keithley representative or the fac­tory for further information.

1.4 MANUAL ADDENDA

Any improvements or changes concerning the Model
82-DOS or this instruction manual will be explained on a
separate addendum supplied with the package. Please be
sure to note these changes and incorporate them into tlw
manual before operating or servicing the system.

Addenda concerning the Models 230-1, 590, 595, and
5909 wiIl be packed separately with those instruments.

1.5 SAFETY SYMBOLS AND TERMS

The following safety symbols and terms may be found on
one of the instruments or used in this manual:

The WARNING heading used in this and other manuals

cautions against possible hazards that could lead to per­sonal injury or death. Always read the associated infor­mation very carefully before perfodg the indicated
procedure.

A CAUTION heading outlines dangers that could dam­age the instrument. Such damage may invalidate the

warranty.

1.6 SPECIFICATIONS

Detailed specifications for the Model 82-DOS system can
be found at tlw front of this manual. Specifications for the
individual instruments are located in their respective in-

struction manuals.

1.7 UNPACKING AND INSPECTION

1.7.1

Upon receiving the Model 82-DOS, carefully unpack alI
instruments and accessories from their respective ship­ping cartons, and inspect all items for any obvious physi­cal damage. Report any such damage to the shipping
agent at once. Save the original packing cartom for possi­ble future reshipment.

Unpacking Procedure

The Q 1 symbol on an instrument indicates that you
should consult the operating instructions in the associ-

ated manual.

Table l-l.

Supplied Equipment

Quantity Description

I

230-l Voltage Source
590 c-v Analyzer
595 Quasistatic C-V Meter
5951 Remote Input Coupler
5909 Capacitance Sources
4801 Low noise BNC cables (4’)

3
2
1

1

1

l-2

7051-2 BNC cables

7007-l Shielded IEEE-488 cables (lm)
7007-2 Shielded IEEE-488 cable (2m)
5957 C-V Software Package and manual
IOtecli Driver488 Software and manual

1.7.2

Supplied Equipment

Table l-1 summarizes the equipment supplied with the
Model 82-DOS system.

Application

Supply +lOOV DC offset, control 5951 frequency
Measure lOOkI&, 1MHz C and G
Measure C, Q/t; supply staircase bias waveform

Connect 590 and 595 to DUT

System configuration/calibration

Connect 5951 to DUT and instruments

Connect ine.trument control and voltage signals

Connect instruments to bus

Connect controller to instrument bus

‘Control Model 82 system

BEE-488 bus software driver.

General Information

SECTION 1

1.8 REPACKING FOR SHIPMENT

Should il become necessary to return any of the instn­ments for repair, carefully pack them in their original
packing cartons (or the equivalent), and be sure to in­clude the following information:

. Advise as to the warranty status of the equipment.
. Write ATI’ENTION REPAIR DEPARTMENT on the

shipping label.

e Filloutandindudetheserviceformwhichislocatedat

the back of this or one of the other instruction manuals.

1.9 COMPUTER REQUIREMENTS

The following paragraphs discuss minimum computer
requirements, supported graphics and interface cards,
supported plotters and printer, and required system soft-

ware.

Table 1-2. Computer Hardware Requirements

Description

Computer
MinimumRAM
Disk drives

Monitor/graphics

card
Instrument interface
Plotter/printer inter­face

‘Compatible 386.based machines such as the Compaq 386 can also
be used. NOTE: When using Compaq portable, select IBM graphics
mode (see Compaq manual). Compaq graphics are not supported.

IBM AT, PS/Z, or compatible*
640KB
Hard drive, one l.Z.MB 5-l/4”
or 720KB 3-l/2” floppy disk
drive
Color or monochrome (see
Table l-3)
IEEE488 (see Table 14)
Serial, parallel, or IEEE488

times. A 386-based computer is recom­mended for best performance.

1.9.2

Supported Graphics Cards

Table l-3 summarizes the graphics cards supported by
Model 82-DOS.

Table 1-3.

Graphics Cards Supported by

Model 82-DOS

Graphics Boards

1

IBM CGA or 100% compatible
IBM EGA or 100% compatible
IBM VGA or 100% compatible (EGA mode)
Tseng EVA
Tecmar Graphics Master
Hercules Monochrome or 100% comuatible
T&Video AT
T&Video HRCGB
Sigma Color 400
AT & T 6300

corona PC

corona PC400

Corona ATP
H.P. Vectra
T. I. Professional
Genoa SuperEGA HiRes

NOTE: VGA operates in EGA made.

1.9.3

Supported IEEE-488 interfaces

I

Thecomputermustbeequippedwithasuitable~EE-488

interface so that it can communicate with the Models
230-L 590, and 595. Table 14 summarizes IEEE-488 inter­faces supported by Model 82-DOS.

1.9.1 Computer Hardware Requirements

Model 82-DOS is intended to run on an IBM AT, PS/Z, or
compatible computer. Compatible 386-based machines
such as the Compaq 386 can also be used. Table 1-2 sum­marizes therequiredATcomputerconfiguration,includ­ing minimum RAM, disk drive complement, and inter­faces required.

NOTE
Although not required, a coprocessor is rec­ommended to minimize analysis calculation

Table l-4. IEEE-488 Interfaces Supported

by Model 82-DOS

Interface

GP488/GP488A/

1 Manufacturer

IOtech

Power488
PC II, PC IL4, or PC III

PC488 and 4488~CEC
GPIB
GP488/2*

‘For B/2 computers

National Instruments
Keithley Instruments
IBM
IO&h

I

l-3

SECTION 1
General Information

1.9.4

Recommended Printers and
Plotters

In order to obtain hard copy plots of your curves, it will

be necessary for you to connect a suitable printer or plot-

ter to the serial or parallel port of your computer.
Tablel-5 summarizes recommended printers, and
Table 1-6 summarizes recommended plotters. Note that
the plotters must support HPGL graphics language.

Table 1-5. Recommended Printers

Printer

NEC 8023,8025, C. Itoh Prowriter
Cannon BJSO, Epson IX, RX
Okidata 92,93
Smith Corona DlOO, Epson MX, IBM Graphics
Tektronix 4695/6
C. Itoh 24LQ, Toshiba 24 pin
Epson LQ1500, HP Laser Jet+*
Okidata 192+
HP Think Jet
NEC Pinwriter

Table 1-6. Recommended Plotters

Hewlett-Packard 7470,7475,7440
Watanabe IX&-Plot
Houston DMP-XX
Roland DXY-800

NOTE All plotters must support HPGL graphics
language.

Additional plotter and printer requirements, including
how to configure the software for the plotter and printer
type, and maximum resolutions are discussed in para­graph 2.4.8.

1.9.5 System Software Requirements

As summarized in Table l-7, the required installed sys­tem software includes MS-DOS or PC-DOS (version 3.2
or higher). IOtech Driver488 is supplied with Model
82-DOS. Microsoft BASIC 7.1 (not supplied) is required
only if you intend to modify the software in some way.

‘Compatible HI’ laser printers may also be used.

Table 1-7. System Software Requirements

I Software

MS-DOS or PC-DOS, Version 3.2 ox higher
Microsoft BASIC, Version 7.1* Compile/link source code
IOtech Driver488** or Driver488/2 IEEE-488 interface driver

‘BASIC 7.1 is not supplied and is required only for those who wish to modify one of the program.
“Driver488 is supplied with Model 82-DOS.

Additional information on software installation is cov­ered in paragraph 2.4.

I Comments

Operating system

l-4

SECTION 1

General Information

1.10 SERVICE AND CALIBRATION

Service and calibration information on the Models 590,
595, and 230-l can be found in their respective manu­als.The Model 5951 Remote Input Coupler cannot be cali­brated or repaired by the user, so it must be returned to
the factory or authorized service center for repair or cali­bration. If the Model 5951 is to be returned, proceed as
follows:

1. Complete the service form at the back of the manual
and include it with the unit.

2. Care~vuacktheunitintheori~inalpackinacarton
or its eq&lent.

3. Write ATTENTION REPAIR DEPARTMENT on the
shipping label.

-_ -

1.11 OPTIONAL ACCESSORIES

1.11.1 Connecting Cables

Model 4801 Low-noise Cable: Low-noise coaxial cable,

1.2m (48 in.) in length, with a male BNC connector on
each end.

(metric). Available as Model 7007-l Urn, 3.3 ft. long), and

Model 7007-2 (2x11,6.6 ft. long).

Model 7051 BNC to BNC Cables: 5O.Q (RG-58C) BNC to
BNC coaxial cables, available as Model 7051-2 (0.6x11,2 ft.

long), Model 7051-5 (1.5~ 5 ft. long), and Model 7051-10
(3m, 10 ft. long).

1 .l 1.2

Model 1019A-2 Fixed Rack Mount Kit: Mounts theMod­&230-l and595sidebysideinastandard19~inchrackor
equipment cabinet.

Model 2288 Fixed Rack Mount Kit: Mounts the Model
590 in a standard 19 inch rack or equipment cabinet.

Model 8000-14 Equipment Cabinet: A standard 14-inch
high, 19 inch wide equipment cabinet, which can be used
to enclose the Model 82-DOS instruments. Rack mount
kits (above) are also required.

Rack Mount Kits

Model 4803 Low-noise Kit: Includes 15m (50 ft.) of low­noise coaxial cable, 10 male BNC connectors, and five fe­male chassis-mount BNC connectors.

Model 7007 Shielded IEEE-488 Cables: Shielded
IEEE-488 cables with a shielded connector on each end

1 .I 1.3

The Model 5958 C-V Software Utilities add BTS (bias

temperature stress) and Zerbst (C-t measurement and
analysis) capabilities to the Model 82-DOS. A user-sup­plied Temptronic 0315B Thermochuck is required for the
BTS utility.

Software Utilities

1-5

SECTION 2

Getting Started

2.1 INTRODUCTION

Section 2 contains introductory infomation to help you
get your system up and running as quickly as possible.
Section 3 contains more detailed information on using
the Model 82-DOS system.

section 2 contains:

2.2 Hardware Configuration: Details system hardware
configuration, cable connections, and remote input
coupler mounting.

2.3 System Power Up: Covers the power up procedure
for the system, environmental conditions, and
warm up periods.

2.4 Computer Hardware and Softwm Installation:
Outlines methods for installation of the computer
software and hardware.

2.5 Software Overview: Desaibes the purpose and
overall configuration of the Model 82-DOS soft­ware.

2.6 SystemCheckout:Givestheprocedureforchedcing
out the system to ensure that everything is working
properly.

2.2 HARDWARE CONFIGURATION

The system block diagram and connection procedure are
covered in the following paragraphs.

2.2.1

An overall block diagram of the Model B-DOS system is
shown in Figure 2-l. The function of each instrument is
as follows:

Model 230-l Voltage Sauce: Supplies a DC offset volt­age of up to rtlOOV, and also contmls operating frequency
of the Model 5951 Remote Input Coupler.

Model 590 C-V Analyzer: Supplies a 1OOkHz or 1MHz
test signal and measures capacitance and conductance
when making high-frequency or simultaneous C-V
measurements.

Model 595 C-V Meter: Measures low-frequency (quasis­tatic) capacitance and Q/t, and also supplies the stepped
bias waveform (?zZOV maximum) for simultaneous low­and high-frequency C-V measurement sweeps.

System Block Diagram

2-1

SECTION 2
Getting Started

Figure 2-Z.

_--

I

System Block Diagram

output

TO 590 Otiput

1 0”tD”t I

Model 5951 Remote Input Coupler. Connects the Model
590 and 595 inputs to the device under test. The input
coupler contains tuned circuits to minimize interaction

between low- and high-frequency measurements.

Computer (IBM AT or PW2): Provides the user interface
to the system and controls all instruments over the
IEEE-488 bus, processes data, and allows graphing of re­sults.

Model 5909 Calibration Set: Provides capacitance refer­ence sources for cable correcting thesystem to the test fix­ture.

2.2.2 Remote Input Coupler

The Model 5951 Remote Coupler is the link between the
test fixture (which contains the wafer under test) and the

measuringinstruments,theModels590 and595.Theunit
not only simplifies system connections, but also contains
the circuitry necessary to ensure minimal interaction be­tween the low-frequency measurements made by the
Model 595, and the high-frequency measurements made
by the Model 590.

The front and rear panels of the Model 5951 are shown in
Figure 2-2 and Figure 2-3 respectively. The front panel
includes input and output jacks for connections to the de­vice under test, as well as indicators that show the se­lected test frequency 0OOkHz or lh@Iz) for high-fre­quency measurements. The rear panel includes a binding
post for chassis ground, BNC jacks for connections to the
Models 590 and 595, a ribbon cable connector (which con-

nects to the Model 230-l digital I/O port), and a digital
I/O port edge connector providing one TTL output, four
TTL inputs, digital common, and +5V IX.

2-2

SECTION 2

Getting Started

0

OUTPUT and INPUT - BNC jacks used to con­nect the Model 5951 to the test fixture containing
the device under test.

2 Frequency indicators (1OOkHz and 1MHz) -

3

Shows the selected test fxquency for high-fre­quency c-v measurements.

‘igwe 2-2.

Model 5951 Front Panel

6

WARNING
Maximum voltage between the outer shell of the BNC
iacks and earth mound is 30V RMS. Maximum OUT­PUT voltage is ZiOV; maximum INPUT voltage is 30V
peak. Exceeding these values will create a shock haz­ard.

2-3

SECTION 2
Getting Stark-d

CHASSIS binding post-Provides a convenient
connection to chassis ground of the Model 5951.

WARNING
Connect CHASSIS to earth ground to avoid a possible
shock hazard. Use #I6 AWG or larger wire.

2 Ribbon cable-connects to the Model 230-l digi-

3

talI/Oportforfrequencyswitchingoftheremote
coupler.

A

3 DIGlTAL I/O - Passes through the Model 230-l

3

dlgtal I/O port signals for control and sensing of
other components (for example, light control and
door dosed status).

‘igure 2-3.

Model 5951 Rear Panel

4 TO 590 INPUT - Connects to the Model 590 IN-

0

0

0

PUT jack on the front panel of the instrument.

5 TO 590 OUTPUT - Connects to the Model 590

OUTPUT jack on the front panel.

6 TO 595 METER INI’UT- Connects to the Model

595 METER INPUT jack on the rear of the ins&u­ment.

WARNING

Maximum voltage between the outer shell of the BNC

jacks and earth ground is 30V RMS.

2-4

SECTION 2

Getting Started

2.2.3 System Connefitions

Supplied Cables

Table 2-l summarizes the cables supplied with the
Model 82-DOS system along with the application for

each cable. Note that low-noise cables are provided for
making connections between the chuck and the C-V
measurement instruments. The Model 4801 cables are

each four feet long. Be careful not to use the Model 7051
BNC cables in place of the low-noise cables (Model 4801),
as doing so will have detrimental effects on your meas­urements.

Connection Procedure

Use Figure 2-4 and Figure 2-5 as a guide and connect the

equipment together as follows. Note that the stacked ar-

Table 2-1. Supplied Cables

rangement shown in the figures is recommended, but
other setups can be used, if desired.

NOTE
AU equipment should be turned off when
making connections.

1. Connect a Model 4801 cable between the Model 590
INPUT jack and the TO 590 INPUT jack of the Model
5951 Remote Input Coupler. Connect a second
Model 4801 between the Model 590 OUTPUT jack
and the TO 590 OUT jack of the Model 5951.

2. Connect &Model 5951 INPUT and OUTlWT jacks
to the chuck test fixture using Model 4801 cables.

NOTE

OUTPUT should be connected to the sub-

strate contact, and INPUT should be con-

netted to the gate metallization contact. This

arrangement will minimize reading noise.

I

Quantity 1 Model ( Description

5 4801 4’ BNC Low Noise
3 7051-2 2’ BNC (RG-58)
2 7007-l lm shielded IEEE-488
1 7007-2 2m shielded IEEE-488

1 1. 1 Ribbon cable

‘Supplied with Model 5951 (Pati No. CA-911

595

C-V Meter Voltage salrce

590

C-V Analyzer

OUtpUt

Input

230-l

/

/

1 Amlication

5951 Remote
Input Coupler

-- I

NOTE: Connect 5951 output 10

substrate, input to gaie

I

To Test

Fixture

Fiwre

2-4. Svstem Front Panel Connections

2-5

SECTION 2
Getting Started

590 ‘” 590

Input oulput

nnnnnnnnnnnnnn

J

I-\ 1

I I

‘I

Figure 2-5. System Rear Panel Connections

3. Connect the Model 5951 TO 595 METER INPUT jack
to the Model 595 METER INPUT jack using a Model

4801 cable.

4. Connect theribboncable totheModel5951,andthen

connect the opposite end of the cable to the digital
I/O port of the Model 230-l. Both connectors are
keyed so that they can be installed only in one direc­tion.

5. Using a Model 7051 cable, connect the Model 595

METER COMPLETE OLJTl’LlT to the EXTERNAL
TRIGGER INPUT jack of the Model 590.

6. Using a second Model 7051 BNC cable, connect the

Model 595 VOLTAGE SOURCE OUTPUT to the
OUTPUT LO of the Model 230-l Voltage Source. In a
similar manner, use a Model 7051 BNC cable to con­necttheModel230-1 OUTPUTHI to&EXTERNAL
BIAS IM’IJT of the Model 590 C-V Analyzer.

7. Connect the Model 5951 chassis ground post to earth

ground using heavy copper wi&

WARNING
The Model 5951 must be connected to earth
ground using #16 AWG or larger wire.

_

plied IEEE-488 cables. Typically the shorter cables will be
used to connect the instruments together, while the
longer cable connects the instruments group to the com­puter. Figure 2-6 shows a typical arrangement for
IEEE-488 bus connections. See paragraph 2.4 for a de­scription of IEEE-488 interfaces for the IBM computer.

2.2.5

In many cases, the wafer prober will be located inside a
faraday cage to minimize noise. In these situations, the
remotecoupleritselfcanalsobeplacedinsidethecagefor
convenience and to
course, there is sufficient room.

The coupler can be permanently mounted to the sides or
top of t&z faraday cage by rembving the rubber feet and
using the threaded holes in the bottom case for mount­ing. Appropriate mating holes can be drilled in the fara­day cage, and the coupler should be secured to the cage

with #6-32 screws of sufficient length.

Remote Coupler Mounting

minimize cable lengths, assuming of

2.2.4

In order to uSe the system, the instruments must be con- case,ortheymaycontact thecircuitboardin-

netted to one another and the computer using the sup-

2-6

IEEE-488 Bus Connections

Be sure that the mountine screws do not ex­tend more than l/4” in& the Model 5951

side.

CAUTION

Getting

SECTION 2

Figure2-7showsatypicalinstallationforcouplermomt­ing, including suggested cable routing. Note that the
Model 5951 chassis should be grounded to the faraday

595

C-V Meter

Figure 2-6.

230-I

Voltage source

C-V Analyzer

System IEEE488 Connections

cage by connecting a grounding strap or wire between
the cage and the coupler chassis ground binding post.

compatible) computer

‘igure 2-7. Remote Coupling Mounting

2-7

SECTION 2

Getting Started

2.3 SYSTEM POWER UP

Line voltage selection, power connections, environ­mental conditions, and instrument warm-up periods are
covered in the following paragraphs.

2.3.1

The Model 230-1,590 and 595 are designed to operate
from 105-125V or ZO-25OV, 50 or 60Hz AC power
SOUTC~S (special transformers can be factory installed for
90-1lOV and 195-235V AC voltage ranges). The factory
setting for each instrument is marked on the rear panel of
that particular instrument. The operating voltage for
each instrument is either internally or externally selec­table; see the appropriate instruction manual for details.

Instrument Power Requirements

CAUTION

Do not attempt to operate an instrument on a
supply voltage outside the allowed range, or
instrument damage may occur.

2.3.4

The system can be used immediately when all in&u­ments are first turned on; however, to achieve rated sys­tem accuracy, all instruments should be turned on and al­lowed to warm up for at least two hours before use.

2.3.5

Follow the general procedure below to power up the
Model 82-DOS system.

1.

2.

3.

4.

Warm Up Period

Power Up Procedure

Connect the instruments together as outlined in
paragraph 2.2.3.
Connect the instruments to the IEEE-488 bus of the
host computer following the procedure given in
paragraph 2.2.4.

Turn on the computer and boot up its operating sys-

tem in the usual manner. Refer to the computer
documentationforcompletedetailsforyourparticu­lar system.
Turn on each instrument by pressing in its front
panel power switch. Verify that each instrument
goes through its normal power up routine, as de­scribed below.

2.3.2 Power Connections

Each instrument should be connected to a grounded AC
outlet using the supplied AC power cord or the equiva­lent.

WARNING
Each instrument must be connected to a
grounded outlet using the supplied power
cord in order to ensure continued protection
from possible &chic shock. Failure to use a
grounded outlet and a 3-w& power cord
may result in personal injury or death be­came of electric shock.

2.3.3 Environmental Conditions

For maximum measurement accuracy, all instruments
and the remote coupler must be operated at an ambient
temperature between 0 and 40°C at a relative humidity
less than 70%, and within *5’=C of the cable collection
temperature.

Model 230-l

The instrument first turns on all LEDs and segments.

The software revision level is then displayed as in

this example:
813
The unit then displays the primary address:
IE 13
Verify the primary address is 13; set it to that value if

not.
The unit begins normal display.

Model 590

1.

The Model 590 first displays the software revision
level as in this example:

590 REV D13

2.

The instrument then displays the programmed pri­mary address:

IEEE ADDRESS 15

Verify the address is 15; program it for that value if
not.

2-8

SECTION 2

Getting Stuarted

3. Finally, the unit begins displaying normal readings.

Model 595

The instrument first displays the ROM self-test mes­sage:

*.a
The unit then displays normal readings.

Press MENU and verify the primary address is 28;
set it to that value if not.

2.3.6 Line Frequency

The Models 230-l and 590 can be operated from either 50
or 6OHz power sources with no further adjustments.
However, for the Model595 to meet its stated noise sped­fications, the unit must be programmed for the line fre­quency being used. To set or check the Model 595 line fre­quency, proceed as follows:

1.

Turn off the Model 595 if it is presently huned on.

2.

Press and hold the MENU button and then turn on
the power. Release the MENU button after the dis­play blanks on power up.

3.

Press the MENU button and note that the frequency
selection prompt is displayed:

2.4.1

Interface Card Installation

Model 82-DOS can be used with the following IEEE-488

interfaces:

l IOtech GP488, GP488A, or Power488

. National Instruments PCIl, PCIIA, and XIII

l Keithley Instruments PC-488-CEC and 4-488~CEC
l Capitol Equipment Corp. PC-488 and 4488

. IBMGPIB
. IOtech GP488/2 (for I’S/Z)

Note that all the above cards except the Gl’488/2 canuse

the Driver488 bus driver supplied with Model 82-DOS.

Before installation, note the following interface board

settings so that you can properly configure the bus driver
software during driver software installation:

l I/O port address

. DMA status

l Interrupts
l System controller

After noting these settings, install the interface card in the

computer. Refer to the documentation supplied with the
card for detailed installation procedures.

Fr=50
or,

Fr=60

4.

Use the ADJUST keys to toggle the unit to the de­siredfrequency.

5.

Press SHIFT EXIT to return to normal operation.
Note that the frequency selection prompt will re­main in the menu until power is removed.

2.4 COMPUTER HARDWARE AND SOFTWARE INSTALLATION

The following paragraphs discuss interface installation
and installation of the supplied Model 82-DOS software.
Required installation steps include:

l IEEE488 interface card installation
l Model 82 software installation
l IEEE488 driver software installation

. CONFIG.SYS file modification.

2.4.2

Software backup

Before installing the software on your hard disk, it is
strongly recommended that you make backup copies of
each of the disks supplied with Model 82-DOS. Use the
DOS DISKCOPY command to make copies. For two­floppy disk systems, the general command syntax is:

DISKCOPY A: B: <Enter>

Here, the source disk is assumed to be in drive A, and the
target (copy) disk is in drive B.

Similarly, the command for single-floppy drive systems
is:

DISKCOI’Y A: A: <Enter>

After copying all supplied disks, put the original disks

away for safekeeping.

2-9

SECTION 2
Getting Started

2.4.3

Memory and Hard Disk
Considerations

In order to use the Model 82-DOS software, you should
have at least 500KB free RAM before running the pro­gram. A minimum of 4MB of free hard disk space is also
recommended. Of course, the amount of space required
depends on how many date and parameter files you in­tend to save.

2.4.4 Model 82-DOS Software
Installation

Follow the appropriateprocedure below to install the
Model 82-DOS software on your hard disk. The follow­ingzEeraphs discuss usingINSTALL.EXE to install the

Place the installation disk in drive A: or B:, then type:

1.

A: <Enter>

0*

B: <Enter>

Type the following to start the installation process:

2.

INSTALL <Enter>

Follow the prompts on the screen to select the direc-

3.

tories for the various Model 82-DOS files and pro­grams.Youcanselectinstallationdefaults,whichare
summarized in Table 2-2, or your own directory
names, as desired.
Continue theinstallationprocessbyselectingappro-

4.

priate graphics cards, printers, and plotters at the ap­propriate prompts. Table 2-3 summarizes graphics
cards, and Table 2-4 lists supported printers and

plotters. Also, refer to paragraph 2.4.8 below for cer-

tain plotter and printer considerations.

NOTE

INSTALL.EXE can also be used to reconfigure
the software after installation. Select the
reconfigure option to change an existing soft­ware configuration Also, you can run
EQUP.EXE to change only graphics cards,
printers, or plotters settings once installation
is complete.

Model S2-DOS will run properly on most

VGA, Super VGA, and 8514 monitor corn­putersystemsintheEGAmodeTouseMode1
82-DOS with any of these gmphics systems,
select the EGA graphics mode at the appropri­ate prompt.

NOTE

Table 2-2. Default Directories

.EXE, configuration file, configgpc
.FWI or other files needed by .EXE
cable calibration file,

CABLECAL.EXE;
CV\MODEL82\DAT
CV\MODEL82\l’AR
CV\MODEL32\SRC

NOTE: C:\IEEE488 is not created by Model &?-Do5 installation program. Refer to bus driver installation instructions.

FILEMP.G.EXE file merge,

Z-10

Table 2-3. Graphics Cards Supported by Model 82-DOS

Resolution

Mode

(pixels)

SECTION 2

Getting Started

IBM color board

Hercules Monochrome
Enhanced Graphics
Adapter (EGA)
TeleVideo AT
TeleVideo HRCGB

Sigma Color 400
AT & T 6300
Corona PC
Corona PC400

Corona ATP
HP. Vectra
T. I Professional
Genoa SuperEGA H&s
IBM VGA or compatible

monochrome 640 x 200

640 x 480
monochrome 720 x 700
16 color 640 x 400
monochrome 720 x 348
16 color 640 x 350
monochrome
monochrome 640 x 400
16 color 640 x 400
16 color 640 x 400
native graphics 640 x400
native graphics 640 x 325
native graphics IBM 640 x 400

l3llUl~tiOn 640 x 200

monochrome 640 x 400
monochrome 640 x 400
monochrome 720 x 300
16 color 800 x 600
16 color 640 x 480
monochrome 640 x 480

2-11

SECTION 2
Getting Started

Table 2-4. Supported Printers and Plotters

Printer/Plotter

C. Itoh Prowriter; NEC 8023; 8025
Epson FX, RX; Cannon BJSO
Okidata 92,93
IBM Graphic or Professional; Epson MX
Tektronix 4695 ink jet printer
Toshiba P321 and l’351 (with unidirectional printing)
Corona Laser printer - REQUIRES AN EXTRA 128k

OF MEMORY
Houston DMP-xx plotters
Hewlett--Packard HP-GL plotters

C. Itoh 24LQ
Watanabe Dig&Plot plotter
Epson LQl500
Smith Corona DlOO
Epson HI-80 plotter
Hewlett Packard LaserJet+ (or compatible)
Micro Peripherals 150,180
Okidata 192+ (eight bit graphics)
CALCOMP ColorMaster (BEING TESTED)
Toshiba 1340 (No unidirectional)
I-IF ThinkJet (SW5 up) (6.5 x 8.5 in.)
Roland DXY-800 Plotter
Toshiba I’351C with color ribbon
NEC Pinwriter P series
Quadram QuadLaser (with vector software)
NEC Pinwriter I’ series with color ribbon

2.4.5 IEEE-488 Driver Software
Installation

FILES = 20
BUFFERS = 20

NOTE
After modifying CONFIGSYS, reboot the
computer (press Ctrl-Alt-Del) to place the

changes into effect.

2.4.7 Installation Verification

Before running the C-V software, it is recommended that
you perform the procedure below to make sure that the
IEEE488 interface and software were installed properly.

1. With the power off, connect the instruments to the
IEEE-488 interface of the computer.

2. Turn on the instruments, and make sure that their
primary addresses are set to the default values

(230-1=13,590=15,595=28). If not, program or set the

primary address accordingly.

3. Turnon thecomputer, andallowitto bootupDOSin
the usual manner.

4. Load interpretive BASIC (BASICA or GW-BASIC)

into the computer.

5. Type the lines of the test program below into the

computer.

6. RUN the program, then verify that a reading from

each instrument appears on the computer CRT, and
that each instrument is programmed as follows:

The driver software for the IEEE488 interface card
should be installed per manufacturer’s recommenda-

tions. Refer to the IEEE-488 driver software documenta­tion for complete details. Use the supplied Driver488 for
all cards except PS/2 cards. Use Driver488/2 for I’S/2
cards.

2.4.6

CONFIG.SYS Modification

For most computer configurations, you should assign at
least 20 buffers and files in CONFIGSYS. Use a text edi­tor to modify or add the following lines:

2-12

230-l: 1OV should be programmed on its display.

590: the unit should display “MODEL 82-DOS” on

front panel

595: the instrument should be in the current mode.

If a single instrument fails to respond, check to see that it
is programmed for the correct primary address, and that
it is connected properly to the IEEE488 bus. If none of the
instruments respond, verify that the interface board and
software were properly installed.

SECTION 2

Gettim Stnrted

TEST PROGRAM

OPEN “\DEV \ IEEEOUT” FOR OUTPUT AS #1

10
20 IOCTL#l,“BREAK”

PRINT#l “RESET”

30

OPEN “\‘DEV \ IEEEIN” FOR INPUT AS #2

40

PRINT#l “CLEAR’

50

ITJiVT #;,-OUTPUT U;TO,OX”

60
70 PlUNT#I,“ENTXR 15”
80 LINE IivPuT#2,R$
90 PRINT “MODEL 590 READING: “;R5
100 PRINT#l,“ENTER 28”
110 LINE LNPuT#2,R$
120 PlUNT “MODEL 595 READING: “;R$
130 PRINT#l,“ENTER 13”
140 LINE JNPuT#2,R$

PRINT “MODEL 230-l DATA: “;R$

150
160 PRINT#l,“OUTT’uT 15;DMODEL*S2-DO%”

170 PRJNT#I,“OuTPuT 28;FlX”
180 PRINT#1,“0urIw”r 13;VlOx”
190 END

2.4.8

Plotter and Printer Considerations

Printer Hardcopy Resolution

Selecting a plotting option on the graphics menu gener­ates a half-page plot with low resolution. To control the
size and resolution from the graphics menu, type in one
of the following letters:

graphics language. For HP plotters not listed, first try one
of the listed plotters (use 7475A for 7470A).

Those who are using Hewlett-Packard serial plotters

should select eight data bits and one stop bit for serial pa-

rameters.

Serial Printer and Plotter Support

Model 82-DOS will drive printers or plotters connected
to either the serial or parallel port of your computer. If
you are using the serial port, you must initialize the port
byselectingtheproperparameters foryourparticularse­rial connection during installation or reconfiguration.

The graphics routines that support hardcopy use polling
to send characters to the serial port. Polling means that a
character is sent and a check is made to see if the printer is
busy. If so, the routine waits until the device is ready to
accept another character. However, if the device con­nected to the serial port sends back any character other
than buy, the transmission protocol will be interrupted.
For that reason, be sure to set your printer or plotter to its
least intelligent mode (turn off handshaking and status
reports). Also, be sure to use the proper serial cable, as the
interrupt used requires that all signal lines be present.

Laser Printer Support

half page, low resolution

“m”

half page, high resolution

“M”
“1” full page, low resolution

full page, high resolution

“L”

Selecting one of these options automatically generates
the corresponding plot.

Section 4 discusses analysis in detail

Plotter support

Model 82-DOS supports Hewlett-Packard, Watanabe,

Houston, and Epson pen Plotters that use the HPGL

Model 82-DOS supports a Hewlett-Packard LaserJet +
(or compatible) printer with full-page 300dpi resolution.
However, the printer must be equipped with at least

1.5Mb of memory to support this resolution. In addition,
some computer configurations may have insufficient
memay for the required large bit map. In those cases, an

“m” (300dpi, l/2 page) or “1” (150dpi, full page) plot can

be performed.

GPIB (IEEE-488) Bus Plotter Support

A GPIB plotter can be used with Model 82-DOS by select­ing the appropriate device(s) from the menu (select the

“output to Driver 488 plotter” option). The plotter must,
of course, be connected to the IEEE-488 bus of the com­puter. The plotter must be set for the addressable mode
using a primary address of 5.

2-13

SECTION 2

Getting Starfed

2.4.9

The following paragraphs discuss the basic procedures

fornmningaModel82-DOSC-Vprogram.Basically,you
can start a C-V program in one of three ways:

. From the main menu.
. From the manual measurement menu, automatically

loading a test parameter file.

. From the analysis menu, automatically loading a data

file.

Starting the Program at the Main Menu

To execute the program from the main menu, simply

type in one of the program names below while in the

\KTHLY-CV\MODE@2 subdirectory. C-V programs

supplied with Model 82-DOS include:

KI82CV.EXE

KI590CV.EXE

Running the Software

This program is the simultaneous C-V
program that controls the Models
230-1,590, and 595 to make simulta­neon C-V measurements and per­form analysis.

This program controls the Model 590
alone for high-frequency C-V meas­urements (see Appendix E).

KI82CV FilenamePAR <Enter>

Note that you must specify the .PAR extension to invoke
this option. To load parameter file that is not located in
the default parameter (PAR) directory, include the com­plete path with the file name. If the file is not located in

the specified directory, an error message will be dis­played and the program will execute from the main
menu instead.

Starting the Program at the Analysis Menu

In a similar manner, you can execute the program begin­ning at the analysis menu and automatically load a speci­fied data file by including the data file name on the com­mand line, for example:

KI82CV Filename.DAT <Enter>

Note that you must include the .DAT extension to use
this option. To load a data file that is not located in the de
fault data (.DAT) directory, include the complete path
with the file name (for example, C:\MOREDATA\file­name.DAT). If the specified data file is not located in the
indicated directory, an error message will be displayed,
and the program will begin execution at the main menu.

Kl595CV.EXE

Note that you need not type in the .EXF extension to exe-

cute a program from the DOS prompt. For example, to

load and run KI82CV.EXE from the DOS prompt, simply

type:

KI82CV <Enter>

The program to be executed must be located
in the current default directory to run.

Starting the Program at the Manual Measurement

Menu

You can execute the program starting at the manual
measurement menu and automatically load a specified
test parameter file by including the test parameter file
name with the execution command, for example:

This program controls only the Model
595forquasistaticC-Vmeasurements
(see Appendix E).

NOTE

Default Paths

Normally, the Model 82-DOS software uses the default
paths specified during installation for parameter and
data files (see Table 2-2). If you specify a new path when
loading or saving files, the new path wiU become the de­fault path for the current session. The default path speci­fied during installation will be restored the next time the
C-V program is run.

Run Time Considerations

In order to useMode 82-DOS programs properly, it may
be necessary to remwe software drivers (such as GPIB
print or mouse drivers) from your computer configura­tion to free up enough memory or to avoid conflicts. Use
EDLIN or other text editor to remove the driver installa­tion statements from CONFIG.SYS or AUTOEXEC.BAT
as required. Reboot your computer after making modifi­cations before running the Model 82-DOS software.

Also, be careful not to touch front panel buttons on in­struments while a program is running. Doing so may
change instrument settings and lead to erroneous results.

2-14

SECTION 2

Getfing Started

Navigating Menus

To select a given menu item, simply type the indicated
number, and press the <Enter> key. To move up to a pre­vious menu level, simply choose the return menu selec­tion, or press the <Eso key. At the highest menu level,
youwillbepromptedtoselectwhetherornotyouwishto
return to DOS.

2.4.10 Default Material Constants

As shipped, Model 82-DOS is designed to work with de­vices with a silicon substrate, a silicon dioxide insulator,
and ahuninum gate material. You can modify the soft­ware for use with other types of materials, if desired. Re­fer to Appendix A for details.

2.5 SOFTWARE OVERVIEW

The main sections of the Model 82-DOS software are
briefly discussed in the following paragraphs. These de-

scriptions follow the order of the main menu shown in
Figure 2-8. For detailed information on using the soft-

ware to make measurements and analyze data, refer to

Sections 3 and 4.

2.5.1

System Reset

tance present in the system that could affect measure­ment accuracy; the procedure also allows you to verify
connection problems.

There are two important aspects to system characteriza­tion:

Quasistatic capacitance (Co), high-frequency capaci­tance (C$, conductance (G), and Q/t (current) are
measured at a specified bias voltage to determine
system contribution of these factors. Ce CH, and G
canbe suppressed in order to assure maximum accu­racy. If abnormally large error terms are noted, the
system should be checked for poor connections or
other factors that could lead to large errors.
Q/t vs. V sweeps can be performed to determine the
presence of leakage resistance and external leakage
current sources. C vs. V sweeps can be done to test
for the presence of voltage dependent capacitance in
the system.

See Section 3 for details

System checkout should be performed whenever the
configuration, step V, or delay time is changed. Probes­up suppression should precede every measurement to
achieve rated accuracy.

By selecting option 1 on the main menu, you can easily re­set the instruments and the software to default condi­tions. SDC and IFC commands are sent over the bus to re­turn the instruments to their power-on states and remove
any talkers or listeners from the bus. Cable calibration
constants are also reloaded by this option.

2.5.2

option 2 on the main menu allows you to perform a

“probes up” characterization of the complete system
from the measuring instruments, through the connecting
cables and remote coupler, down to the prober level.
Characterization is necessary to null out (Co, CR, or G), OI
remedy leakage currents, resistances, and stray capad-

System Characterization

2.5.3

Compensating for Series

Resistance and Determining
Device Parameters

Option3onthemainmenuallowsyoutodetermineopti­mum parameters for measuring the device under test.
Key areas of this process are:

1.

A C-V sweep is performed and graphed to deter­mine accumulation and inversion voltages.

2.

The device is biased in accumulation to determine
Rsm and Cox.

3.

The device is biased in inversion to determine Cm
and equilibrium delay time. A user-supplied light
can be controlled to help achieve equilibrium more
rapidly.

2-15

SECTION 2
Getting Started

1

/

** MODEL 82 MAIN MENU **

1. Reset Model 82 CV System

2. Test and Correct for System Leakages and Strays

3. Compensate for Rseries and Determine Device Parameters

4. Make CV Measurements

5. Analyze CV Data

6. Return to DOS

NOTE: ESC always returns user back one MENU level.

Enter number to select from menu :

\

Figure 2-8. Main Menu

2.5.4

Option 4 on the main menu allows you to perform a si-

multaneous C-V sweep on the device under test. As pa-

rameters are measured, the data are stored within an ar­ray for plotting or additional analysis, as required.

The two general types of sweeps that can be performed
include:

1. Accumulation to inversion: Initially, the device is bi­ased in accumulation, and the bias voltage is held

2-16

Device Measurement

static until Q/t reaches the system leakage level. The
sweep is then performed and the data are stored in
the array.

2. Inversion to accumulation: In this case, the device is

first biased in inversion, and the sweep is paused un­til equilibrium is reached (when Q/t equals the sys­tem leakage level). A submenu option allows you to
control a light within the test fixture (using the

Model 5951 digital I/O port) as an aid in attaining

the equilibrium point. The sweep is then completed
and the data are stored in an array for further analy­sis.

SECTION 2

Getting Started

2.5.5 Data Analysis and Plotting

Option5onthemainmenuprovidesawindowtoanum­ber of analysis and graphing tools. Key options here in­clude printing out parameters, graphing array data on
the CRT or plotter, graphical analysis, and loading or

storing array data on disk. Note that this option can also
be directly selected from menus providing sweep meas­urements without having to go through the main menu.

2.5.6 Returning to DOS

Selecting option 6 returns you to DOS. IFC and SDC are
sent to the instruments before exiting the program.

2.6 SYSTEM CHECKOUT

Use the basic procedure below to check out Model
82-DOS to determine if the system is operational. The
procedure requires the use of the Model 5909 Calibration

Sources, which are supplied with Model 82-DOS. Note

that this procedure is not intended as an accuracy check,

but is included to show that all instruments and the sys­tem are functioning normally. Before performing this
procedure, you should verify that the IEEE-488 interface
and software are properly installed (see paragraph 2.4).

2. Power up the system using the procedure given in
paragraph 2.3, and boot up the computer.

3. RunKI82CV.EXE.

4. Select option 2 on the main menu, and then option 2
on the subsequent menu. Connect the 1.8nF capx­tor and verify that Co is within 1% of the 1kHz ca­pacitor value, an that Q/t is <IpA. Correct any ca-

bling problems before proceeding.

5. Run the CABLECAL.EXE utility and perform cable
correction (see Appendix G).

6. Follow the prompts and connect the Model 5909

Calibration Sources to the Model 5951 INPUT and
OUTPUT cables using the BNC adapters supplied
with the Model 5909.

7. After correction, return to KI82CV.EXE main menu

selection 2, then select option 2 on the submenu.
Connect the l&F capacitor; verify that Co is within
I % of the 1kHz capacitance, and the CH is within 1%
of the 1OOkHz of 1MHz value (depending on the se­lected frequency).

8. Select option 3 on the leakage and strays menu.

9. Start the sweep, and observe the Model 590 voltage
display. Verify that the bias voltage readings step
through the range of -2V to +2V in 20mV incre­ments.

2.6.2

System Troubleshooting

2.6.1

1. Connect the system together, as discussed in para-

symptom

No instrument responds over bus.
One instrument fails to respond.
Improper low-frequency measurements.
Improper high-frequency measurements.
5951 does not change frequency.

No DC bias applied to device.
Excessive leakage current.
Erratic readings.
590 readings not triggered.
Probes up Q/t vs. V improper.
Probes up C vs. V improper.
Cable correction impossible.
Reading dynamic range insufficient.

Checkout Procedure

graph 2.2.

Table 2-5.

System Troubleshooting Summary

Possible Cause(s)

Units not connected to controller, controller defective.
Unit not connected to bus, improper primary address, unit defective.
595 not connected properly, 595 defective.
590 not connected properly, ribbon cable not connected, 590 defective.
Ribbon cable not connected, 5951 or 230-l defective, loose ribbon ca-

ble connection.
595 or 230-l not connected properly, 595 or 230-l defective.
Wrong cables used, dirty jacks, test fixture contamination.
EMI interference, poor connections.
595 to 590 trigger cable not connected.
External leakage current present.
External voltage-dependent capacitance present.
Wrong cables used, 590 defective.
Connecting cables too long, excessive fixture capacitance.

Troubleshoot any system problems using the basic pro-

cedure shown in Table 2-5. For information on trouble­shooting individual instruments, refer to the respective
instruction manuals

2-17

3.1 INTRODUCTION

This section gives detailed information on using Model
82-DOS Software to acquire C-V data and is organized as
follows:

SECTION3

Measurement

3.9

Measurement Considerations: Outlines numerous
factors that should be taken into account in order to
maximize measurement accuracy and minimize er­rors in analysis.

3.2 Measurement Sequence: Outlines the basic meas­urement sequence that should be followed to ensure

accurate measurements and analysis.

3.3 System Reset: Describes how to reset the in&~-

ments in the system.

3.4 Testing and Correcting for System Leakages and

Strays: Describes the procedure to test the complete
system for the presence of unwanted characteristics
such as leakage resistance, current, and capacitance.

3.5 Correcting for Cabling Effects: Details cable correc-

tion that must be used in order to ensure accuracy of
high-frequency C-V measurements.

3.6 Characterizing Device Parameters: Covers the pro­cedures necessary to determine RF,-, Chow, COX,
and optimum delay time to attain device equilib­lium.

3.7 Making C-V Measurements: Describes in detail the
procedures necessary to measure the device under
test and store the resulting data in arrays.

3.8 Light Connections: Discusses connection of a light
to the system as an aid in attaining device equilib­rium.

3.2

The measurements should be carried out in the proper
sequence in order to ensure that the system is optimized
and error terms are minimized.Thebasicsequenceisout­lined below; Figure 3-l is a flowchart of the sequence.

Step 1: Test and Correct for System Leakage and Strays

Initially, you should test your system to determine if any

problems such as excess leakage current or unwanted ca­pacitance are present. You should correct any problems
before continuing. Note that the system need be tested

only when you change scme aspect of its configuration

(such as connecting cables or test fixture).

Suppression, which is also available under this menu op-

tion, should be performed before each measurement for

optimum accuracy. Note that suppression can also be

performed from a measurement menu by pressing ‘7’.

MEASUREMENT SEQUENCE

3-1

SECTION 3

Measurement

Step 2: Correct for Cabling Effects

Start

9

(Use CABLECAL.EXE)

Perform

sweep

0

Cable correction is necessary to compensate for transmis­sion line effects through the connecting cables and re­mote input coupler, which are more significant at higher
frequencies and with longer cables or switches in the sys­tem. Failure to perform cable correction will result in sub­stantially reduced accuracy of high-frequency C-V meas­urements. In order to perform correction, it will be neces­saryfor you to connect the Model 5909 calibration capaci­tors and use the CABLECAL.EXE utility program. Cable
correction must be performed the first time you use your
system, and it need be performed only if the system con­figuration is changed in some manner, or if the ambient
temperature changes by more than 5°C.

Step 3: Determine Device Parameters

Each device must be tested to determine optimum accu­mulation and inversion voltages. Once those voltages
values are determined, the device should be biased in ac­cumulation to determine Cox, Tax, and/or gate area, as
well as Rsena~. The device under test should then be bi­ased in inversion to determine C~(W and to determine op­timum delay time necessary to maintain device equilib­rium.

NO NO

r-52

I:‘

I

!igure 3-1.

NLWJ NLWJ

Device ? Device ?

Ye5 Ye5

Determine R ser,es,

Cmin , COX , and

Delay Time

Measurement Sequence

Step 4: Make C-V Measurements

Now that all the “housekeeping”, so to speak, is out of the
way, a sweep can be performed to determine how such
device parameters as capacitance change with applied
DC bias voltage. First, of course, it will be necessary for
you to select such parameters as range, frequency, and
bias voltage values. As the sweep is performed, meas­ured values are stored in arrays for later retrieval and
analysis.

Step 5: Analyze C-V Data

Once a sweep has been performed, and the results are
stored safely in computer arrays, you can apply any one
of a number of different analysis techniques to the data.
Raw data plotting (hard copy) or graphing (CRT) of such
parameters as low and high frequency capacitance vs. V
can be performed. Analysis features including doping
profile, flatband calculations, and interface trap density
are also provided. See Section 4 for analysis details.

3-2

SECTION 3

Measurement

3.3 SYSTEM RESET

Option 1 on the main menu (Figure 3-2) allows you to re­set your Model 82-DOS System and return the instn­ments to their default conditions. When this option is
executed, the IEEE-488 lFC (Interface Clear) and SDC
(Selective Device Clear) commands are sent over the bus,
and you will then be returned to the main menu after a
two-second pause. During this period, the computer will
display the following message:

Outputting IFC and SDC to reset system.....

-

** MODEL 82 MAIN MENU **

1. Reset Model 82 CV System

2. Test and Correct for System Leakages and Strays

3. Compensate for Rseries and Determine Device Parameters

4. Make CV Measurements

5. Analyze CV Data

6. Return to DOS

The IFC command removes any talkers and listeners

from the bus, and the SIX command returns instruments

to their default conditions. The Models 230-l and 595 will

always rehun to the same default state, but the default

conditions for the Model 590 are determined by SAVE 0.

See the appropriate instruction manuals for details. Note

that the instruments are automatically reset when the

program is first run and immediately prior to exiting the

p~Ogr~.

\

Figure 3-2.

NOTE: ESC always returns user back one MENU level.

Enter number to select from menu :

Model 82 Main Menu

33

SECTION 3

Measurement

3.4 TESTING AND CORRECTING FOR SYSTEM LEAKAGES AND STRAYS

The system should be tested with the probes up to deter-

mine if any sources of large errors such as defective ca­bles are present. The following paragraphs give an over­view of the process, discuss menus, and detail the proce­dure for testing you particular system.

Suppression should be performed prior to eachmeasure­ment for optimum accuracy.

** Measure stray capacitance and leakage currents **

Open the circuit a+z the device (i.e. probe up).
Suppress should be done before each device measurement.

1. Set Measurement Parameters

2. Monitor/Suppress System Strays and Leakages

3. Measure Leakages Over Sweep Voltage Range

4. Analyze Sweep Data for C and Q/t vs. V

5. Return to Main Menu

3.4.1 Test and Correction Menu

To test your system, select main menu option 2, Test and

Correct for System Leakages and Strays.

Figure 3-3 shows the overall test and correction menu for

Model 82-DOS software. Through this menu, you can se-

lect measurement parameters, monitor leakage levels,
perform a probes-up sweep, analyze the results, and sup­press offsets. These aspects are covered in the following
paragraphs.

Figure 3-3.

3-4

Enter number to select: from menu :

Stray Capacitance and Leakage Current Menu

SECTION 3

Measurement

3.4.2

Menu Selections

By selecting option 1 on the system testing menu, you can
access the parameter selectionmenushowninFigue3-4.
You can also access this menu by pressing ‘M” from
measurement menus. This menu allows you to program
the following parameters:

1. Range for both quasistatic and high-frequency

Parameter Selection

measurements (200pF or 20. The measurement

** Measurement Parameter List **

Rang.5:

Freq :

Model : 1
Start V: 2.00 v.
stop v: -2.00 v.
Bias V: 0.00 v.

2

2

Enter Rl for 2OOpF. R2 for 2nF
Enter Fl for lOOKHZ, F2 for 1NBZ
Enter Ml for parallel, M2 for series
Enter An, -120 <= n <= 120
Enter On, -120 <= n <= 120
Enter Bn, -120 <= n <= 120

TDelay: 0.07 sec. Enter Tn, 0.07 <= n <= 199.99
step v:

ccap:
Filter: 2

20 q V. Enter SlO, S20, S50 or SlOO

1

Enter Cl for leakage correction off, C2 for on

Enter 11 for filter off, 12 for on

ranges of both the Models 590 and 595 are set by this

parameter.

2. Frequency for high-frequency measurements
(1OOkI-k or IMHz). This parameter sets the operat-

ing frequency of the Models 590 and 5951.

3. Model (parallel or series). Model selects whether the
device is modeled as a parallel capacitance and con­ductance, or a series capacitance and resistance. See
paragraph 3.9.6.

4. StartV: (-12O<V<120). StartVistheinitialbiasvolt­age setting of a c-v sweep.

5. Stop V: C-120 < V 2 120). Stop V is the &al bias volt-
age setting of a C-V sweep.

Figure 3-4.

Number of samples = 93

Sweep will take = 0.4 minutes.

NOTE: 1) Keep start V and stop V within 40 volts of each other.

2) Keep number of samples within 4 and 1000 points with filter off.

3) Keep number of samples within 50 and 1000 points with filter on.

Enter changes one change at a time. Enter E when done, * for files.

Enter selection :

Parameter Selection Menu

3-5

SECTION 3

Measurement

6.

Bias V: Bias V is a static DC level used when static
monitoring the system (for example, when testing
for leakages and strays), and is the voltage level as­sumed when a sweep is completed.

7.

T delay: (0.07 ST < 199.99sec). Note that the time de­lay must be properly set to maintain device equilib­rium.

8.

Step V: (lOmV, 2OmV, 5OmV or 1OOmV): Step V is the
incremental change in voltage of the bias staircase
waveform sweep.

9.

C-Cap: (Corrected capacitance): Uses the corrected
capacitance program of the Model 595 when en­abled. C-Cap should be used only when testing
leaky devices.
Filter: Sets the Model 595 to Filter 2 when on, Filter 0

10.

(off) when off. NOTE: Turning off the filter wiLl in­cr+sethenoiseby2.5timimes. Note that the parameter
does not affect the Model 590 filter, which is always
on.

Il.

Number of Samples: Displayed at bottom of menu.

12.

Sweep length: Indicates how long the sweep will
take.

1.

The maximum difference between the programmed
Start V and Stop V is 40V. Exceeding this value will
generate an error message.
The number of points must be between 4 and 1000

2.

with the filter off, or between 50 and 1000 with the fil­ter on to avoid curve distortion.

3.

Bias voltage polarity is specified at the gate with re­spect to the substrate. For example, with a positive
voltage, the gate will be biased positive relative to
the substrate. Thus, an n-type material must be bi­ased positive to be in the accumulation region.

NOTE
The voltage displayed on the front panel of
the Model 590 is of the opposite polarity from
the voltage displayed by the Model 82-DOS
softwarebecause of the gate-to-substrate volt­age convention used. As described in Section
2, INPUT should be connected to the gate ter­minal, and OUTPUT should be connected to

the substrate terminal.

Programming Parameters

To program a parameter, type in the indicated menu let­ter followed by the pertinent parameter. The examples
below will help to demonstrate this process.

Example 1: Select lh4Hz High-frequency Operation

To select high frequency operation, simply type in F2 at

the command prompt, and press the ENTER key.

Example 2: Program a c15V Bias V

Type in B15, and press the ENTER key.

Example 3: Select O.lsec Delay Time

Type in TO.l, and press the ENTER key.

Example 4: Program a 20mV Step Voltage

Type in S20, and press the ENTER key.

Saving/Recalling Parameters

By pressing the “*” key, you can save or load parameters
to or from diskette. The menu for these operations is
shown in Figure 3-5. Press “S” (save) or “L” (load) to
carry out the desired operation. You will then be
prompted to type in the filename to be saved or loaded.
Anerrormessagewillbegivenifafilecannotbefoundor
will be overwritten.

NOTE
Do not add the .PAR extension to the file-

name.

When the save option is selected, the parameter values
currently in effect will be saved under the selected file­name. Parameters loaded from an existing file will over­write existing parameters.

Programming Considerations

When selecting parameters, thereareafewpoints to keep
in mind, including:

3-6

NOTE
To load or save parameters to a different drive

or a directory other than PAR, specify the
complete path in the filename (for example,
AMYFILE, or C:\I’ATH\MYFILE).

** Store I Load system parameters **

Loading parameters overwrites the system parameters.
A file must already exist to be Loaded.
A file to be Stored must not exist.
Note: Do not add .PAR to the end of the typed name!

Enter S or L to store or load parameters, enter E to exit.

SECTION 3

Measurement

Enter Selection :

Figure 3-5. Save/Load Parameter Menu

Rehuz~ing to Previous Menu

After all parameters have been programmed (or loaded
from disk), press “E or ESC” to rehun to the system leak­age testing menu

program is first run by specifying the parameter test file­name at run time. See paragraph 2.4.9 for details.

Saving and Loading from a Floppy Disk

Loading Parameters at Run Time

A parameter file can be automatically loaded, when the

To save or load to a floppy disk, simply include the drive

designation before the filename. (For example: A: SAM­PLE will load or save SAMPLE to drive A:.

3-7

SECTION3

3.4.3

Description

Before perfotig a test sweep, you should observe sys­tem leakage current and capacitance and fix any prob-

lems before continuing. Once system leakage levels have

been reduced, proceed to paragraph 3.4.4 to perform a
probes-up sweep of the system. Paragraph 3.9 discusses
these factors in more detail.

Procedure

1.

Range: 200pF
Frequency: 1OOlcHz or 1MHz as required
Model: Parallel
Bias V: O.OOV
T Delay: 0.07s~
Step V: 5OmV
c-cap: Off
Filter: On
Press “E” then ENTER when parameters have been

programmed, then select option 2, Monitor/Sup­press System Strays and Leakages.

2.

3.

4.

5.

Viewing Leakage Levels

Select option 2 on the main menu followed by option
1 (Set Measurement Parameters) on the following
menu. Program the following:

Disconnect the device from the system; in other
words, place the probes in the up position. Close the
shield on the test fixture.
If necessary, press “R” to turn off suppress and dis­play “raw” readings.
You wiIl then see a display similar to the one shown
in Figure 3-6. The values shownare representative of
what to expect in a typical system, but your values
may be somewhat different. Note that uncompen­sated readings are displayed (readings not compen­sated for series resistance, or gain or offset values).
Note the quasistatic and high-frequency capacitance
and the leakage (Q/t) level. These values should be

as small as possible. Ideally, stray capacitance

should be less than 1% of the capacitance you expect
to measure for optimum accuracy. Also, leakage cur­rent should be as low as possible.

6.

If desired, press “Z” to suppress Co, CH, and G.

7.

Press “Q” to exit the menu.

Analyzing the Results

There are two key items to note when performing the

aboveprocedure: (1) excessiveleakagecurrent (Q/t), and
(2) too much stray capacitance. If excessive leakage cur-

rent is noted, you should check the foIlowing:

Make .sure the proper cables are installed in the COT-

1.
rect places. Be certain you have not interchanged
Model 4801 (low-noise) cables with the Model 7051

(50% cables.

2.

Make sure all connecting jacks and connectors are
free of contamination. Clean any dirty connectors
with methanol, and allow them to dry thoroughly
before use.

3.

Becertainthatyouare,infact,m~ga”probes-up”
measurement.

4.

Check to see that no leakage paths are present in the
test fixture.

5.

If necessary, tie down cables to avoid noise currents
caused by cable flexing. Also, avoid vibration during
testing.

Things to check for excessive stray capacitance include:

1.

Verify that all cables are of the proper type and not of
excessive length.

2.

Verify the integrity of all cable shields and that the
shield connections are carried through to the connec­tors.

3.

Again, make sure the procedure is being performed
in the “probes-up” configuration.

4.

Use a test fixture of good, low-capacitance design.

5.

Make certain the test fixture shield is in place when
characterizing the system. The same precaution
holds true when characterizing or measuring a de­vice.

3-8

SECTION3

M&7SUV3fX?~t

/

** Monitor/Suppress System Strays and Leakages at Bias V **

Open the circuit at the device (i.e probe up).

press 'M' to set measurement parameters
press 'Z' to suppress Cq, Ch, G (probe up).
press 'R' to remove suppress.
press 'Q' to Quit.

(note: Keyboard response time is affected by delay time)

Suppress is OFF.

UNCOMPENSATED READINGS

Quasistatic :

High freq :

Cq (pF)

+0.5

Ch (pF)

-0.3

Q/t (PA)

+o.ooo

G (US) Bias Vgs

-2.OOOOE+OO

-l

+o.ooo

Figure 3-6. Monitor Leakage Menu

3-9

SECTION 3

Measurement

3.4.4

Description

This aspect of system leakage testing allows you to deter­mine if there are any voltage-dependent leakages in the
system. Basically there are two important points here: (1)

how the leakage current varies as the bias voltage

changes, and (2) apparent quasistatic capacitance vari­ation with changes in voltage. These considerations are
discussed more completely in paragraph 3.9.

Procedure

1. Select option 2 on the main menu, then option 1, Set

Range: 200pF
Frequency: 1OOkHz or lMHz, as required

Model: Parallel

Start V: Most negative voltage generally used.
Stop V: Most positive voltage usually used.

Bias V: O.OOV
T delay: 0.07sec
Step V: 1OOmV

System Leakage Test Sweep

Measurement Parameters, and program the follow­ing parameters.

c-cap: Off
Press “E” then ENTER to exit. Select option 3, Meas-

ure Leakages Over Sweep Voltage Range.

2.

Place the probes in the up position to disconnect the

device from the system.

3.

Make sure the test fixture shield is in place before

starting the procedure.

4.

Press “R” to display “raw” readings. The computer
display will show leakage levels, as shown in
Figure 3-7. Note that uncompensated readings are

displayed (reading not compensated for series resis-

tance, or gain and offset vahxs).

5.

Press ‘3” to initiate the sweep. Duringthe sweep, the
computer witl display the following:

Sweep in progress
Also, the sweep length and voltages will be dis-

played.

6.

At the end of the sweep, select option 4, Analyze
Sweep Data, and note the following menu is dis­played.

1. Graph both CQ and CH vs. Gate Voltage.

2. Graph Q/t Current vs. Gate Voltage.

3. Graph Conductance vs. Gate Voltage.

4. Return to Previous Menu.

7.

Select options 1 and 2 on the menu to graph both qu­&static and high-frequency capacitance vs. gate
voltage, and Q/t current vs. gate voltage.

3-10

** Manual Start Sweep Measurement **

Open the circuit at the device (ie. probe up).

press 'M' to set measurement parameters

press '2' to suppress Cq, Ch, G (probe up).

press 'R' to remove suppress.

press 'S' to start the sweep

press 'Q' to Quit.

(note: Keyboard response time is affected by delay time)

SECTION 3

Mensurement

Figure 3-7.

Suppress is OFF.

Quasistatic :

High freq :

Diagnostic Sweep Menu

Cq (pF)

+0.3

Ch (pF)

-0.3

Sweep will take = 0.4 minutes.

UNCOMPENSATED READINGS

Qlt (PA)

+o.ooo

G (US) Start Vgs

-3.OOOOE+OO +I.960

3-11

SECTION 3

Measurement

Analyzing the Results

The leakage current you may observe during testing
could be from two main sources: (1) constant leakage cur­rents due to such sources as cables, and (2) voltage-de­pendent leakage currents caused by leakage resistances.
A typical constant leakage current curve is shown in
Figure 3-8, while a Q/t curve due to leakage resistance is
shown in Figure 3-9. In the first case, note that the current
is constant and does not depend on the applied voltage.
For the case of the curve dependent on leakage resistance,
however, the current is directly proportional to the volt­age, as is the case with any common resistor. The resis­tance, incidentally, is simply the reciprocal of the slope of
the line.

Since quasistatic capacitance is determined by integrat­ing the current, the presence of unwanted leakage cur­rent will skew your quasistatic C-V curves. Figure 3-10
shows the effects of constant leakage current. Here, the
normal parasitic capacitance, CP, is skewed upwards
with an additional “phantom” capacitance added to the
normal parasitic capacitance. The same type of curve
skew will also occur with normal measurements, but its
effect will usually be less noticeable because of the larger
capacitance levels involved.

C

---------- ----_-----_ c With

Leakage

-- C Without
Leakage

”

‘@ire 3-8.

‘igure 3-9.

l&age Due to Constant Current

Q/t Cum with Leakage Resistance

V

F

‘igm 3-10. Constant Leakage Current Increases

Quasistatic Capacitance

A more serious situation is present in the case of the vary­ing current, as shown in Figure 3~11. Now, the usually
flat capacitance curve has been tilted, resulting in what is
essentially a voltage-dependent capacitance. Again, the

same curve-tilting effects can be expected for normal

measurements, although usually to a lesser degree.

The high-frequency capacitance curves will not generally

showanyvoltage-variability,andwillshowmainlypara­sitic capacitance at the frequency of interest. Such curves
cm also provide a good frame of reference for the quasis­tatic curves, as both quasistatic and high-frequency
curves should be flat and very similar as long as leakage
currents are sufficiently low.

The G vs. V curve shows AC loss at the selected measure-

ment frequency UOOkHz OI 1MI-M. The high-frequency
conductance value may represent a leakage resistance

that is AC coupled into the test fixture.

3-12

SECTION 3

Measurement

C

, C With

/’

A’

/~

/’

-------___ L--------- c Witho”,

/’

/’

/’

-I-

/

/’

‘igure 3-11. Quasistatic Capacitance with and

without Ledage Current

3.4.5 Offset Suppression

Description

Leakage

Leakage

v

controlled from a measurement menu by pressing “Z”
(suppress on) or “R” (suppress OffI.

Procedure

1. Disconnect the device from the system; in other
words, place the probes in the up position. Close the
shield on the probe fixture.

2. Select option 2, Monitor/Suppress System Strays
and Leakages. You will then see a display similar to
the one shown in Figure 3-6. The values shown here
are representative of what to expect in a typical sys­tem, but yours could be somewhat different.

3. Press ‘7’ to suppress the leakage values. The Model
590 will be drift corrected, and its zero mode will be
enabled to suppress CH and G. Suppress on the
Model 595 will also be enabled to suppress CQ after a

15-second pause for setting. The statuS of suppress
(on) will be displayed on the screen.

4. Press “Q” to return to the previous menu once sup­pression is complete.

Disabling Suppress

By selecting option 2 on the system leakage test menu,
you can monitor the parameters listed below at a fixed
bias voltage. This feature will give you an opporhmity to
suppress these leakage values to maximize accuracy.
This suppression procedure should be carried out before
each verified or performed measurement for optimum
accuracy.

NOTE

Large leakage capacitances and conductances
should not be suppressed. Determine the
source of the problem and correct it before us­ing your system if large offsets are noted.

Monitored parameters include:

CQ (qUhSt&iC CapKit~CL?)

Q/t (leakage current)
CH (high frequency capacitance)
G (conductance)
VGS (gate bias voltage)

Suppressed parameters include CQ, CH, and G. Note that
Q/t is not suppressed. Note that suppress on/off can be

To disable suppress and display raw readings, simply
press “R” at the command prompt. Note that current

suppress values will be lost when suppress is disabled.

3.5 CORRECTING FOR CABLING EFFECTS

Cable correction is necessary to optimize accuracy of
high-frequency C-V measurements, and to align CQ and
Cti for Dn measurements. The process uses the
CABLECAL.EXE utility and involves connecting c&bra­tion capacitors with precisely known values to the con­necting cables in place of the test fixture.

The following paragraphs discuss required calibration
SOUK~S as well as the overall cable correction procedure.

3.5.1 When to Perform Cable Correction

Cablecorrectionmustbeperforrnedthefirsttimeyouuse
your system. Thereafter, for optimum accuracy, it is rec­ommended that you cable correct your system whenever
the ambient temperature changes by more than 5OC from
the previous correction temperature. You can cable cor­rect your system daily, if desired, but doing so is not ab­solutely essential.

3-13

NOTE
Cable correction parameters and source val­ues are

“PKG82CALCAL” file. These correction pa­rameters ax automatically retrieved during
program initialization. This file must be in the
default directory when running the program.

stored on

disk in the

Table 3-1. Cable Correction Sources

Nominal 1kHz 1ookHz

Value* VahlP Vahle**

lMH7.

Value**

I 47pF I I I I

180pF

3.5.2

Table 3-l summarizes the recommended calibration ca­pacitors, which are part of the Model 5909 calibration set
supplied with Model S&DOS. The values shown are
nominal; you must use the lkHz, lOOkI%, and 1MHz val­ues marked on the sources when correcting your system.
Space has been provided inTable 3-1 for you to enter the
actual values of your sources.

Recommended Sources

NOTE
The first time you cable correct your system, it
will be necessary for you to enter your actual
SOutTe

CABLECAL.EXE. See paragraph 3.5.4.

values while running

3.5.3 Source Connections

In order to correct your system, it will be necessary for
you to disconnect your test fixture and connect each cal-

470pF

I 1.8nF I I I I

I

“Nominal values included withModel 5909 Calibration Source
“Enter values from SOUTC~S where indicated.

bration capacitor in its place when prompted to do so, as

shown in Figure 3-12. Use the supplied female-to-female
BNC adapters to connect the sc~uxes to the cables.

When using the sources, be sure not to handle them ex-

cessively, as the resulting temperature rise will change

the source values due to temperature coefficients. This

temperature change will degrade the accuracy of the COT-

rection process.

I

I I

I

Remote Input Coupler

Figure 3-12. Cable Correction Connections

5951

SECTION 3

Measurement

3.5.4 Correction Procedure

As noted earlier, the following procedure must be per­formed the first time you use your system, and it should
also be performed when the ambient temperature
changes by more than 5°C from the correction point.

NOTE
This correction procedure uses the
CABLECAL.EXE utility, which is described in
more detail in Appendix G.

Proceed as follows:

1.

While in the \KTHLY~CV\MODEI&? directory,
type in the folio wmg to run the cable calibration uiil­ity:

CABLECAL <enter>

2.

To load an existingPKG82CAL.CAL calibration con-

stants file, press Alt-F, then select Load on the menu.
S+ct the existing PKG82CAL.CAL file, or type in
the name of the file (l’KG82CAL.CAL).

3.

Press Ah-E, then select Cable Cal Model 82 to cali­brate the Model 82-DOS system.

4.

If you are cable correcting your system for the first

time, enter the nominal, lkHz, lOOkHz, and 1MHz
values where indicated (use the <Tab> key to move
around selections). Capacitor #l is the smaller of two
values, and Capacitor #2 is the large capacitor value
for a given range (see Table 3-l). Select OK after en­tering source values to begin the calibration process.

5.

Choose the CALIBRATE selection to perform the ca­ble calibration procedure.

6.

Follow the prompts on the screen to complete the
calibration process. During calibration, you will be
prompted to connect calibration capadtors, or to
leave the terminals open in some cases. If any errors
occur, you will be notified by suitable messages on
the screen.

7.

After calibration is complete, you must save the new
calibration constants to the PKGSZCAL.CAL file in
order for the Model 82-DOS main program to find

them at run time. To do so, Press U-F, the select

Save or Save As as required. If you use Save As, be
sure to specify the I’KG82CALCAL filename.

3.5.5

Optimizing Correction Accuracy to
Probe Tips

To correct as close as possible to the probe tips, construct
two BNC cables (504 low noise if possible) equal in
length to the distance from the 1astBNC connectors to the
probe tips. Connect these substitute cables in place of the
last cables with prober, and perform the correction proce­dure outlined in paragraph 3.5.4. After correction, re­place the original cables.

3.6 CHARACTERIZING DEVICE PARAMETERS

Before device measurement, it is necessary to determine

sweep parameters to make certain the device is properly
biased in inversion and accumulation during the sweep.
Also, optimum delay time, trzrau, must be determined to

ensure that the device remains in equilibrium. In addi­tion, it is often desirable to verify Cox, Cm, and F&m,
The following paragraphs discuss the procedures for
characterizing these device parameters.

3.6.1

To characterize device parameters, select option 3, Com­pensate for Rseries and Determine Device Parameters on
the Model 82-DOS main menu. The menu shown in
Figure 3-13 will be displayed. By selecting appropriate
options, you can perform the following:

1.

2.

3.

4.

5.

Device Characterization Menu

Program measurement parameters as required.
Perform a diagnostic C-V sweep.
Graph the results of the diagnostics C-V sweep in or­der to check for proper accumulation and inversion
voltages, as well as to verify device type.
Bias the device in accumulation to determine Rsenn~,
Cm, Tax, and/or gate area.
Bias the device in inversion and determine Cm and
equilibrium delay time.

3-15

SECTION 3

Measurement

/--

** Characterization of Device Parameters **

OPEN CIRCUIT SUPPRESS SHOULD PRECEDE EACH MEASUREMENT

1. Set Measurement Parameters

2. Run Diagnostic CV Sweep

3. Graph Diagnostic Sweep Data to Determine INVERSION 6 ACCUMULATION Voltages.

4. ACCUMULATION: Determine Rseries, Cox, Tax, and/or Area.

5. INVERSION: Determine Cmin and Equilibrium Delay Time.

6. Return to Main Menu

Enter number to select from menu :

~~~ \

Figure 3-13. Device Characterization Menu

3-16

3.6.2

Running and Analyzing a
Diagnostic C-V Sweep

Before testing for other device parameters, you should
run a diagnostic sweep on the device to check to see that
proper start and stop voltages have been programmed
for the accumulation and inversion of the curve.

Procedure

1. Before running a sweep, verify connections and sup­press if necessary, as outlined in paragraph 3.4.5.

2. Select menu option 1, Set Measurement Parameters,

and program the following:

Range: 200pF or 2nF depending on expected capad­tance

Frequen,cy: 1OOkHz or IMHz, as required.

Model: Parallel

Start V: As required to bias the device in accumula-

ti0*.

Stop V: As required to bias the device in inversion

T delay: 0.07sec

step v: 5omv
c-cap: Off
Filter: On

when progr amming voltage parameters, remember

that the voltage polarity is at the gate with respect to
the substrate. Thus, to begin the sweep in inversion
on an n-type material. Start V would be negative and
Stop V would be positive.

3. Return to the characterization menu by pressing “E”

then ENTER.

4. Select option 2, Run Diagnostic C-V Sweep, on the

menu, then press “Z” to enable suppress if Co, CH, or
G offsets are >I% of anticipated measured values for
the DLJT you are testing.

5. Place the probes down on the contact points for the

device to be tested and close the fixture shield.

6. Press “S” to initiate the sweep after Q/t settles to the

system leakage level. You can abort the sweep, by
pressing any key, if desired.

SECTION 3

Memuement

7.

After you are prompted that the sweep is completed,
press any key to rehun to the characterization menu.

8.

Select option 3, Graph Diagnostic Sweep Data. See
the discussion below for interpretation of the C-V
graph and recommendations. Press ENTER to re­turn to the menu.

Analyzing the Results

The high-frequency curve should be analyzed to ensure
that the sweep voltage range is sufficient to bias the de­vice well into both accumulation and inversion. Typical
C-V curves are shown in Figure 3-14 and Figure 3-15. It
may be necessary to *e-program the Start V or the Stop V

(or both) to bias the device properly. Re-run the sweep to

verify that the new values are appropriate.

The curves can also be used to verify the type of material
under test. As shown in Figure 3-14, an n-type material is
biased in inversion when the gate voltage is substantially
negative, while the device is in accumulation when the
gate voltage is positive. Note that the high-frequency ca­pacitance in inversion is much lower than the high-fre­quency capacitance in accumulation.

The same situation holds true for p-type -es

(Figure Z-15) except the polarities are reversed. In this in­stance, inversion occurs for gate voltages much greater
than zero, while the accumulation region occurs when

the device is biased negative.

The oxide capacitance, Cox, is simply the maximum high­frequency capacitance when the device is biased in ac~u­mdation. Its value can be taken directly from the C-V
plot, or more accurate COX value can be determined using

the procedure in the next paragraph.

The minimum high-frequency capacitance, Cm, can also
be determined from the gmph, or its value can be deter-

mined more accurately using the procedure in paragraph

3.6.4.

3-17

Capacitance

Accumulation

CMIN

-“Gs VTHRESHOLD

Figure 3-14. C-V Characteristics of n-type Material

A

COX

Capacitance

: ;

“FB

GATE BIAS VOLTAGE, V G S

f- Onset of Strong Inversion

P

+VGs

‘igure 3-15.

3-18

-’ GS “FB

C-V Characteristics @p-type Material

“THRESHOLD

GbTE BIAS VOLTAGE, V G s

b

f”GS

SECTION 3

M~USUWll0lt

3.6.3

Determining Series Resistance,

Oxide Capacitance, Oxide Thick-

ness, and Gate Area

Series Resistance

Devices with high series resistance such as those with
epitaxial layers or with substrates with low doping can
cause measurement and analysis errors unless steps are
taken to compensate for this error term. Uncorrected se­ries resistance can result in an erroneously low capaci­tance and a distorted G-V curve. (See Figure 4-8 and 4-9
for a comparison of uncompensated and compensated
G-V curves.)

The Model 82-DOS software uses the three-element
model described in paragraph 4.5.2 to compensate for se­ries resistance. The series resistance, Rs~nrrs, is an analysis
constant that can be entered as described below. The de­fault value for I&- is 0, which means that data will be
unaffected if the value is not changed.

The Model 82-DOS software determines the displayed
value of Rs- by converting parallel model data from
the Model 590 into series model data. The resistance
value corresponding to the maximum high-frequency ca­pacitance in accumulation is defined as Rs~nns.

In conjunction with the added series resistance compen­sation, all displayed readings will be labelled as being
either COMPENSATED or UNCOMPENSATED. Cer­taincompensatedreadingsarealsocompensatedforgain
and offset values (see below). Capacitance and conduc­tance values used for analysis are also compensated for
series resistance.

Oxide Capacitance, Oxide Thickness, and Gate Area

The oxide capacitance, Cox, is determined by biasing the
device in accumulation and noting the high-frequency

capacitance, which is essentially the oxide capacitance,

COX. Once Cm is known, the oxide thickness (tax) or area

(A) can be calculated. Note that these values are saved
with the data and are used for analysis, as discussed in
Section 4.

Procedure

1.

Select option4 on the Characterization of Device Pa­rameters menu.
Press “M”, and program the Bias V parameter neces-

2.
sary to bias the device in strong accumulation. Refer
to the diagnostic curves made as outlined in para­graph 3.6.2 to determine optimum accumulation
voltage. All other measurement parameters should
remain the same as determined in paragraph 3.6.2.

NOTE

The Bias V value must be properly set to bias

the device in strong accumulation in order to
accurately determine both R~ERIES and Cox.

3.

Verify that the probes-up uncompensated capaci­tance is zero, and suppress by pressing “2” if neces-

=Y.

4.

Place the probes down on the device contact points,
and close the test fixture shield.

5.

Note the uncompensated high-frequency capaci­tance displayed on the computer screen, and verify
that it is stable. A typical display, including compen­sated and uncompensated readings, is shown in
Figure 3-16. Note that compensated readings take
into account the effects of R~ERIES, gain, and offset.
To change &ems, Cox, tax, and/or gate area, press

“C”.
The recommended value of RSWES will be calculated
and displayed.
Type in the recommended series resistance value, or
enter your own value, if desired.
The recommended oxide capacitance value will be
displayed. At this point, you can type in the recom­mended value for Cox, or choose your own value, if
desired.

10

You can now choose to enter oxide thickness or gate

area. Enter the gate area in ax?, or enter the oxide
thickness in run. NOTE: To convert run to i , multi­ply by a factor of 10. For example, lnm = 10 i

11

After these parameters are entered, updated Rw.xs,

COX, tax, and gate area values will be displayed.

Press “Q” once data entry is complete to return to the

12

previous menu.

3-19

SECTION 3

Measurement

/

** Determine Rseries, Cox, tax, and/or Area **

(Use measurement parameters to set Bias V to ACCUMULATION)
press ‘M’ set measurement parameters.
press ‘2’ to suppress Cq, Ch, and G (probe up).
press ‘R’ to remove suppress.
press ‘C’ to change Rseries, Cox, tax, and/or Area.
press ‘G’ to change Gain/Offset constants.
press ‘Q’ to Quit.

( keyboard response is affected by delay time )

Suppress is OFF.

Cox(pF) = +O.OOOOEtOO

Area(cm^2) = +O.OOOOE+OO

Rseries(ohms) = t0.0000Et00

tox(nm) = +0.0000Et00

Gain, Offset, and Rseries COMPENSATED READINGS

Quasistatic :

High freq :

Cq (pF)
*0.5

Qlt (PA)

to.000

Ch (pF) G (US)

-0.4

-4.OOOOEtOO

UNCOMPENSATED READINGS

Quasistatic :

High freq : Ch (pF)

Cq (pF)
+0.5

-0.4

Q/t (PA)

to.000

G (US) Bias Vgs

-4.OOOOEtOO to.000

\

Bias Vgs

to. 000

Figure 3-16. Series Resistance and Oxide Gpcitance

Setting Gain and Offset Values

Separate gain and offset constants can be applied to both

CQ and CH to aid in curve alignment or to compensate for
measurement errors. Gain and offset constants are ap­plied to capadtance values used for analysis and are also
used to display compensated readings. Gain and offset

constants can be changed as follows:

1. Select option 4 on the Characterization of Device Pa­rameters menu.

/

2. Press “G” to enter gain and offset constants.

3. Follow the prompts on the screen to enter desired Co
and CH gain and offset constants.

NOTE
To disable gain and offset, enter a value of 1
for gain, and enter a value of 0 for offset.

4. Press “Q” to return to the previous menu.

3-20

3.6.4

Determining CHIN and Optimum
Delay Time

CMIN vescription

The minimum capacitance, Cm, is an analysis constant
used to calculate the average doping concentration, NAVC

(paragraph 4.5.10). Basically, CMIN is the high-frequency
capacitance measured when the device is biased in
stronginversion.TheproceduretodetermineC~~is~~v­ered below.

Delay Time Description

For accurate measurements, the delay time must be care-

fully chosen to ensure that the device remains in equilib­rium in the inversion region during a sweep. The proce­dure covered in this section discusses methods to find the
optimumdelaytimefrom Q/tvs.VandCvs.Vcurves. A
test fixture light can be controlled to speed up device

eqtibnum. Note that the total test time is about 25 times

the maximum delay time, Thmx.

Delay Time Filtering

Since the reading signal-to-noise ratio is proportional to
the delay time, short delay time readings are filtered us­ing an averaging algorithm in order to increase the sig­nal-to-noise ratio of those readings. Averaging is related

to the maximum delay time, Tmar, as follows:

Delay Time

O.OlT,
O.O2T,,
O.O4T,,
O.O6T,,

0.08Tm
>O.lOT,,

Delay Time Menu

Select option 5, Determine Cm and Equilibrium Delay
Time. The computer will then display the menu shown in

Figure 3-17. Through this menu, you can choose the fol-

lowing options.

1. Set Measurement parameters CM).

2. Suppress strays and leakages (2).

3. Display “raw” readings (RI

Number Readings

Averaged

100

50
25

11

6
1

SECTION 3

Measurement

Toggle light on or off CL). If your test fixture is

4

equipped with a light to shine on the device, you can
turn it on to reach the equilibrium point more rap-

idly. See paragraph 3.8 for information on connect­ing a light to the system.
Enter maximum delay time CD). Keep in mind that

5

the plot will take about 25 times the maximum delay

time to complete. For example, if you program a

maximumdelaytimeof lOseconds,theplotwill take

about 250 seconds to complete.

start measurement (S).

6
7

Graph data points (G) CQ and Q/t vs. LoElxv will be

plotted by this option.

Print data points (P). After the measurement is com-

8

pleted, you can print out the data points on the

printer by selecting this option.

View data points on CRT 0%

9

Enter CMIN (0.

10
11

Quit (Q). Pressing “Q” rehuns you to the previous

menu.

Procedure

Perform probes-up suppression, by pressing “2”.

1.

Press “M”, and program the following parameters.

2.
Range: 200pF or 2nF, depending on expected capaci-

tance.
Bias V: As required to bias device in strong inversion

(Use value from diagnostic plot).
Step v: Set amplitude to be used when actually test-

;n device (polarity is derived from Start V and Stop

C-Cap: Off except for leaky devices (see discussion
below).

Filter: On.

Place the probes down on the device contact points

3.

and close the test fixture shield.

4.

Press “D”, and enter the desired maximum delay
time. For an unknown device start with a time of
30-50s~ for easiest interpretation.

If a light is connected to your system, press ‘I” to

5.

turn on the light to achieve equilibrium mc~re rap­idly. Note that the light status is indicated on the
computer CRT.
Observe the Q/t readings on the computer CRT.

6.

Wait until the Q/t value is reduced to the system
leakage level. At this point, the device has reached
equilibrium.
If you are using a light, turn it off once equilibrium is

7.
reached before making the measurement by press­ing “I.“. Again, the stati of the light will be indi­cated on the computer CRT (it may take a few mo­ments for the device to settle after the light is turned
off).

3-21

SECTlON 3

Measurement

** Determine Cmin and Equilibrium Delay Time **

(Use measurement parameters to set Bias V to INVERSION)
press ‘M’ to set measurement parameters
press ‘2’ to suppress Cq, Ch, G (probe up).
press ‘R’ to remove suppress.

press ‘L’ to toggle light on/off press ‘V’ to view data points

press ‘D’ to enter max DELAY TIME

press ‘S’ to start measurement

press ‘Q’ to Quit

press ‘G’ to graph data points

press ‘P’ to print data points

press ‘C’ to enter Cmin

( note: keyboard response is affected by delay time)

Supress is OFF.
Light Drive is OFF.
Max delay time= 10.00 seconds.

Sweep will take 226 seconds.

Gain and Offset COMPENSATED READINGS

Quasistatic :

Cq (pF) Q/t (PA)

+0.3 +o. 100

High freq :

Ch (pF) G (US)

-0.4

-4.OOOOE+OO

Bias Vgs

+o. 000

Figure 3-17. CMLN and Delay Time Menu

8. Press “C” to enter Cm, which is the currently dis­played high-frequency capacitance (CH).

9. Press “S” to begin the delay time measurement. The
computer will display the values of CQ, Q/f and
tom.cw on the CRT, up to a maximum of 11 points.

10. Once all points have been taken, press “G” to gener­ate the Q/t and CQ vs. tDtx.xY graph, an example of
which is shown in Figure 3-18. Note that both Q/t
and CQ will be automatically scaled along the Y axis
of the graph.

11. Once the graph is completed, note both the Q/t and
capacitance curves. The optimum delay time occurs
when both -es flatten out to a slope of zero. For

3-22

maximum accuracy, choose the second point on the
curves after the curve in question has flattened out
(seediscussionbelowforadditionalconsiderations).

12. After choosing the optimum delay time, exit the
graphsubmenu.Youcannowprintoutorviewyour
data points on the printer by pressing “P” or “V” if
desired.

13. Once the optimum delay time has been accurately
determined, press “M”, and program T Delay with
the optimum delay time value determined by this
procedure. Use this delay time when testing and
measuring the device, as desaibed in paragraph 3.7.

Figure 3-18.Q/t and CQ vs. Delay Time Example

SECTION 3

Mt?L2SUZ?tlt?7It

Analyzing the Results

For best accuracy, you should choose a delay time corre­sponding to the second point on the flat portion of both
the capacitance and Q/t curves, as shown in Figure 3-19.
of course, for long delay times, the measurement process
can become inordinately long with some devices. To
speed up the test, you might be tempted to use a shorter
delay time, one that results in a compromise between
speed and accuracy. However, doing so is not recom­mended since it is difficult to quantify the amount of ac­curacy degradation in any given situation.

Determining Delay Time with Leaky Devices

When testing for delay time on devices with relatively
large leakage currents, it is recommended that you use
the corrected capacitance feature, which is designed to
compensate for leakage currents. The reason for doing so
is ikstrated in Figure 3-20. When large leakage currents
are present, the capacitance curve will not flatten out in
equilibrium, but will instead either continue to rise (posi­tive Q/t) or begin to decay (negative Q/t).

Using corrected capacitance results in the normal flat ca­pacitance curve in equilibrium due to leakage compensa-

tion. Note, however, that the curve taken with corrected
capacitance will be distorted in the non-equilibrium re­gion, so data in that region should be considered to be in­valid when using corrected capadtance.

NOTE

Jf it is necessary to use corrected capacitance
when determining delay time, it is recom­mended that you make all measurements on
that particular device using corrected capaci­tance (C-cap on). Return to the set parameters
menu to turn on C-cap.

Testing Slow Devices

A decaying noise curve, such as the dotted line shown in
Figure 3-19, will result if the maximum delay time is too
short for the device being tested. This phenomenon,
which is most prevalent with slow devices, occurs be­cause the signal range is too small. To eliminate such er­r~neous curves, choose a longer maximurn delay time. A

good starting point for unknown devices is a 30-second
maximum delay time, which would result in a five-mir­ute test duration.

3-23

SECTION 3
Measurement

Capacitance

Figure 3-19. Choosing Optimum Delay Time

T Delay

...-‘.-‘-‘-‘-” Erroneous curve because

I-

/-

/-

maximum delay time is
too short

C-Cap off, Positive Wt

Figure 3-20.

3-24

C-Cap off, Negative Wt

Capacitance and Leakage Current Using Corrected Capacitance

3.7 MAKING C-V MEASUREMENTS

The following paragraphs describe procedures for mak­ing C-V sweeps both manually, and automatically. Dur­ing a sweep, the following parameters are stored within
an array for later analysis:

1.

Ca (quasistatic capacitance). CQ is measured by the

Model 595.

2.

Q/t (current), as measured by the Model 595.

3.

CH (high-tiequency capacitance). High-frequency
capacitance is measured at 1OOkHz or 1MHz (de­pendingontheselected testfrequency) bytheMode1

590.
G (high-frequency conductance). The Model 590

4.

measures the conductance of the device at 1OOlcHz or
IMHz, depending on the selected test frequency.

NOTE
When using series model, resistance will be
stored and displayed instead of conductance.

5.

VG~ (gate voltage). The gate voltage is measured by
the Model 590. Note that the gate voltage as it is used
bythecomputerisoppositeinpolarityfromthatdis­played on the front panel of the Model 590 because of
the gate-to-substrate voltage convention used (gate
terminal connected to INPUT; substrate terminal
connected to OLITI’LIT).

3.7.1 C-V Measurement Menu

Figure3-21 shows the menu for C-V measurements.
Various options on this menu allow you to program
menuparameters,manuallystartaC-Vsweep,automati­ally initiate the sweep, and access the analysis functions.
These options are discussed below.

3.7.2 Programming Measurement
Parameters

SECTION 3

Measurement

Range for both quasistatic and high-frequency

1.
measurements (20OpF or 2nF). The measurement
rang&of both the Models 590 and 595 are set by this
parameter.

Frequency for high-frequency measurements

2.

(1OOkHz or X&Hz). This parameter sets the operat­ing frequency of the Models 590 and 5951.

Model (parallel or series). Model selects whether the

3.

device is modeled as a parallel capacitance and con­ductance, or a series capacitance and resistance.

Model affects only high-frequency capacitance and

conductance measurements. See paragraph 3.9.6 for
a discussion of series and parallel model.
StartV: (-12O<V<120). StartVistheinitialbiasvolt-

4.

age setting of a c-v sweep.
Stop V: (-120 <V $120). Stop V is the final bias volt-

5.

age setting of a c-v sweep.
Bias V: Bias V is a static DC level applied to the de-

6.

vice during certain static monitoring functions such
as leakage level tests and determining device Cox
and delay time. Note that the voltage source value
rehnns to the Bias V level after Stop V at the end of
the sweep.

T delay: (0.07 5 T < 199.99%x). Note that the time de-

7.

lay must be properly programmed to maintain de­vice equilibrium during a sweep, as discussed in

paragraph 3.6.

Step V: (lOmV, 20mV, 50mV or 100mV): Step V is the

8.

incremental change of voltage of the bias staircase

wavefonn.ThepolarityofStepVisautomaticallyset

depending on the relative values of Start V and Stop

V. If Stop V is more positive than Start V, Step V is
positive;ifStop VismorenegativethanStartV,Step
v is negative.

C-Cap: ,(Corrected capacitance). Uses the corrected

9.

capacitance program of the Model 595 when en­abled. C-Cap should be used only when testing
leaky devices. As discussed in paragraph 3.6, C-cap
shouldbeusedfordevicemeasurementifyoufound
it necessary to use C-cap when determining delay
time.
Filter: Sets the Model 595 to Filter 2 when on, Filter 0

10.

(offi when off. The Model 590 filter is always en­abled.

Menu Selections

By selecting option 1 on the C-V measurement menu, you
can access the parameter selection menu shown in
Figure 3-22. (Parameters can also be set from the sweep
menu by pressing “M”.) This menu allows you to pro­gram the following parameters:

NOTE
The filter may distort the quasistatic C-V
curve if there are less than 50 readings in the
depletion region of the curve. Turning off the
filter will increase reading noise by 2.5 times.
See the Model 595 Instnxtion Manual for

complete filter details.

3-25

SECTION 3

Measurement

1

** Device Measurement and Analysis **

OPEN CIRCUIT SUPPRESS SHOULD PRECEDE EACH MEASUREMENT

1. Set Measurement Parameters

2. Manual Start CV Sweep

3. Auto Start CV Sweep

4. Analyze Sweep Data

5. Return to Main Menu

Enter number to select from menu :

Figure 3-21. Device Measurement and Analysis Menu

3-26

SEC’llON 3

Measurement

/

** Measurement Parameter List **

Range:
Freq :
Model: 1

2
2

Enter Rl for 2OOpF. R2 for 2°F

Enter Fl for lOOKHZ, F2 for 1MHZ

Enter Ml for parallel, M2 for series
start v: 2.00 v. Enter An, -120 <= n <= 120
stop v: -2.00 v. Enter On, -120 <= n <= 120
Bias V:

0.00 v.

Enter Bn, -120 <= n <= 120

TDelay: 0.07 sec. Enter Tn, 0.07 <= n <= 199.99

step V: 20 mV. Enter SlO, S20, S50 or SlOO

ccap:

Filter:

Number of samples =

1 Enter Cl for leakage correction off, C2 for on

2

Enter 11 for filter off, I2 for on
93

Sweep will take =

NOTE: 1) Keep start V and stop V within 40 volts of each other.

2) Keep number of samples within 4 and 1000 points with filter off.

3) Keep number of samples within 50 and 1000 points with filter on.

Enter changes one change at a tine. Enter E when done, * for files.

Enter selection :

\

0.4 minutes.

Figure 3-22.

Parameter Selection Menu

3-27

SECTION 3

Measurement

Determining the Number of Readings in a Sweep

The number of readings (bias step) in a given sweep is de­termined by Start V, Stop V, and Step V, as well as
whether or not the filter is enabled. The number of read­ings is determined as follows:

R = INT [(ABS~VSTOP - Vsrm) / 2Vsm) - Fl

Where: R = number of readings in the sweep

INT = take the integer of the expression
ABS = take the absolute value of the expression
Vsro~ = programmed stop voltage
Vsr~~r = programmed start voltage
Vm = programmed step voltage
F=Zifthefilterisoff
F=6ifthefilterison

Example: Assume that Start V and Stop V are +lOV end

-lOV respectively, end that Step V is IOOmV. With the fil­ter on, the number of readings is:

R = m [CABS (-x-10)/.2) -61
R=94

Sweep Duration Display

The sweep duration will be displayed on the measure
ment parameters menu. The sweep duration depends on
the number of samples end the delay time.

Programming Parameters

Example 3: Select O.lsec Delay Time

Type in TO.1 and press the ENTER key.

Example 4: Program a 20mV Step Voltage

Type in 520 and press the ENTER key.

Programming Considerations

When selecting parameters, there are a few points to keep
in mind, including:

1.

The maximum difference between the programmed
Start V and Stop V is 40V. Exceeding this value will
generate an error message.

2.

Voltage source polarity is specified at the gate with
respect to the substrate. For example, with a positive
voltage, the gate will be biased positive relative to
the substrate. Thus, an n-type material must be bi­ased positive to be in the accumulation region.

3.

Time delay must be carefully chosen so that the de­vice remains in equilibrium throughout the sweep.
The procedure to determine optimum delay time is
covered in paragraph 3.6. Failure to program proper
delay time will distort quasistatic and high-fre­quency C-V curves. See paragraph 3.9 for additional
measurement considerations.

4.

The filter should be used only when more than 50
readings in the fundamental change area of the
curve are taken; see the Model 595 Instruction Man­ual, paragraph 3.12 for more information. Note that
the parameter menu includes a.note to remind you of
the 50-reading limitation because you will not be
abletoexittheparametermenuwiththefilteronand
<50 points.

To program a parameter, type in the indicated menu let­ter followed by the pertinent parameter. The examples
below will help to demonstrate this process.

Example 1: Select 1MHz High-frequency Operation

To select high frequency operation, simply type in F2 et
the command prompt and press the ENTER key.

Example 2: Program a +15V Bias V

Type in B15 and press the ENTER key.

3-28

Saving/Recalling Parameters

By pressing the “*” key, you can save or load parameters
to or from diskette. Press “S” (save) or “L” (load) to carry

out the desired operation. You will then be prompted to
type in the filename to be saved or loaded. An error mes­sage will be given if a file cannot be found or will be over­wri~en.Donotincludethe.PARextensionwhenspecify­ing the filename.

When the save option is selected, the parameter values
currently in effect will be saved under the selected file­name. l?erameters loaded from an existing file will be up­dated to conform to the new values.

SECTION 3

Measurement

NOTES

1.

Youcanautomaticallyloadaparameterfileandstart
the program at the measurement menu by inclwling
the parameter filename with the program run com­mand. See paragraph 2.4.9.

2.

To save or load a parameter file in a directory other
than the default directory, indude the complete path
in the filename (for example, A: MYFILE or C:

\TESTS\MYFKE).

Returning to Previous Menu

After all parameters have been programmed (or loaded
from disk), press “E” to rehnn to the previous menu.

3.7.3 Selecting Optimum C-V
Measurement Parameters

When pro* amming C-V measurement parameters,
keepthefollowingpointsinmind. Refer toparagraph3.9
for a more complete discussion of these and other consid­erations.

Choosing Optimum Start and Stop Voltages

Most C-V data is derived from the steep transition, or de­pletion region of the C-V curve (see Figures 3-14 and
3-15). For that reason, start and stop voltages should be

chosen so that the depletion region makes up about l/3

to 2/3 of the voltage range.

between having too few data points in one situation, or

too many data points in the other.

The complete doping profile is derived from data taken
in the depletion region of the curve by using a derivative
calculation. As the data point spacing decreases, the ver­tical point scaling is increasingly caused by noise rather
than changes in the desired signal. Consequently, choos­ing too many points in the sweep will result in increased
noise rather than an increased resolution in measure­ment of the C-V waveform.

To minimize noise, choose parameters that will yield a
capacitance change of approximately ten times the per­centage error in the signal. For Model 82-WS, the opti­mum step size is about 5.10% change in capacitance
value per step.

Sweep Direction

For high-frequency C-V sweeps only, you can sweep
either from accumulation to inversion, or from inversion
to accumulation. Sweeping from accumulation to inver­sion will allow you to achieve deep depletion-profiling
deeper into the semiconductor than you otherwise
would obtain by maintaining equilibrium. When sweep­ing from inversion to accumulation, you should use a
light pulse to achieve equilibrium before the sweep be-

gins.

3.7.4 Manual C-V Sweep

The upper flat, or accumulation region of the high-fre­quency C-V curve defines the oxide capacitance, Cox.
Since most analysis relies on the ratio C/&x, it is impor­tant that you choose a start or stop voltage (depending on
the sweep direction) to bias the device into strong BCN­mulation at the start or end of the sweep.

See paragraph 3.6.3 for the procedure to determine COX.

Selecting the Number of Data Points

Therelativevaluesofthestart,stop,andstepvoltagesde­termines the number of data points in the sweep. When
choosing these parameters, some compromise is in order

Description

A manual C-V sweep requires that you observe device

leakage, and then manually trigger the sweep. When
sweeping from inversion to accumulation, you should

wait for the device to attain equilibrium. An optional

light can be controlled to speed up the equilibrium proc­ess.

Procedure

1. Select the Manual Start C-V Sweep Option. The com­puter will display the options in Figure 3-23. Note

that displayed readings are compensated for gain,
offset, and series resistance.

2. Verify a zero probes-up capacitance, and suppress if

necessary (press ‘77.

3-29

SECTION 3

MlSElOWWlt

/

** Manual Start Sweep Measurement **

press ‘M’ to set measurement parameters

press ‘2’ to suppress Cq, Ch, G (probe up).

press ‘R’ to remove suppress.

press ‘L’ to toggle light on/off

press ‘S’ to start sweep
presa ‘Q’ to Quit

(note: Keyboard response time is affected by delay time)

Suppress is OFF.

Light Drive is OFF.

Gain, Offset and Rseries COMPENSATED READINGS

Quasistatic : Cq (pF1

+0.3 +o.ooo

High freq : Ch (pF) G (US) start vgs

-0.5 -3.OOOOE+OO

Sweep will take =

Q/t (pA1

+1.950

1

0.4 minutes.

Figure 3-23. Manual Sweep Menu

3. Press “M” and program the following parameters.
Range: As required for the expected capacitance.

Frequency: 1OOkHz or 1MIIz as required.
Model: Parallel or series as required.
Start V: Accumulation or inversion voltage, as deter-

mined in paragraph 3.6.
Stop V: Inversion or accumulation voltage, as deter-

mined in paragraph 3.6.

T Delay: As required to maintain equilibrium (See

paragraph 3.6)

3-30

Step V: Same as used when testing device in para­graph 3.6.

C-Cap: Off except for leaky devices (see paragraph

3.6).
Filter: On

4. If sweeping from accumulation to inversion, moni­tor the current until it reaches the system leakage
level, as discussed in paragraph 3.4. When the cur­rent reaches the system leakage level, press “S” to
trigger the sweep.

SECTION 3

Measurement

If sweeping from inversion to accumulation, wait
until the device reaches equilibrium (equilibrium oc­curs when Q/t decays to the system leakage level). If
a light is connected to the system, press “L” to turn
on the light to speed up equilibrium. Turn off the
light once equilibrium is reached prior to initiating
the sweep (it may take a few moments for the device
to settle after turning off the light). Press ‘5” to initi­ate the sweep.

The computer will then display a message that the

sweep is in progress. During the sweep, you can
press any key to abort, if desired.
Following the sweep, press any key to return to the
previous menu.
Select option 4 to view and analyze the data. Refer to

Section 4 for complete details on data analysis. Note

that Cox, area, and NEULK values, as previously used
in analysis may not apply to this measurement, and
may require changing before analysis.

3.7.5 Auto C-V Sweep

Description

The auto sweep procedure is similar to that used for man­ual sweep, except that you can program the current trip
pointatwhi~thesweepwillautomaticallybegin. Other­wise, the procedure is essentially the same, as outlined
below.

T Delay: As required to maintain equilibrium (See

paragraph 3.6)
Step V: Same as used when testing device in para-

graph 3.6.
C-Cap: Off except for leaky devices.

Filter: on

4,

Press “G” and the type in the desired leakage trip
point when prompted to do so. Typically, this value
will equal the system leakage level, as determined in
paragraph 3.4.

5.

Press “T” to select above or below trip threshold.

6.

If sweeping from inversion to accumulation, you can
turn on the light (if so equipped) to speed up equilib­rium by pressing ‘I”. Be sure to turn off the light
c~nce equilibrium is reached before initiating the
sweep (it may take a few moments for the device to
settle after huning off the light).

7.

Press “A” to arm the sweep. The computer will con­tinue to monitor readings while waiting for the tip
point.

8.

Once the leakage current reaches the tip point, the
sweep will be initiated automatically. During the
sweep, you can press any key to abort the process.

9.

Once thesweep is completed, press any key to rehwn
to the previous menu.

10.

Select option 4, Analyze C-V Data, to view or graph
the data. Section 4 covers analysis in detail.

3.7.6 Using Corrected Capacitance

Procedure

1. Select Auto Start C-V Sweep. The computer will dis­play the options in Figure 3-24. Note that displayed
readings are compensated for gain, offset, and series

resistance.

2. Verify a zero probes-up capacitance and suppress if
necessary, (press ‘ZN).

3. Press “M” and program the following parameters.

Range: As required for the expected capacitance.
Frequency: 1OOkHz or 1MHz as required.
Model: Parallel or series as required.
Start V: Accumulation or inversion voltage, as deter-

mined in paragraph 3.6.
Stop V: Inversion or accumulation voltage, as deter-

mined in paragraph 3.6.

When making quasistatic measurements on leaky de­vices, it is recommended that you use the corrected ca­pacitancefunctiontocompensateforleakage.Othenuise,
the resulting quasistatic C-V curves will be tilted because
of the leakage resistance of the device or test system.

When using corrected capacitance, it is very important

that the device remain in equilibrium throughout the
sweep. Data taken in non-equilibrium with corrected ca­pacitance enabled should be considered to be invalid,

and the resulting curve will be distorted in the non-eqti­librium region of the curve.

NOTE
If you found it necessary to use corrected ca­pacitance when determining delay time

(paragraph 3.6), it is recommended that you
also use corrected capacitance when measur-

ing the device.

3-31

SECTION 3

Measurement

** Auto Start Sweep Measurement **
press 'M' to set measurement parameters
press '2'
press 'R' to remove suppress.
press 'T'
press 'G' to set start sweep threshold current
press 'L' to toggle light on/off
press 'A'
press 'Q' to Quit

(note: Keyboard response time is affected by delay time)
Suppress is OFF.
Light Drive is OFF.

Arm sweep is OFF

Quasistatic :

High freq : Ch (pF) G (US)

to suppress Cq, Ch; and G (probe up).

to toggle trigger region

to arm sweep

Sweep will take =
Threshold current = 0 pA
Trigger on >= threshold

Gain, Offset and Rseries COMPENSATED READINGS

Cq (pF) Q/t (PA)

+1.5

-0.4 -4.cl000Et00

-0.100

1

0.4 minutes.

Start Vgs

+1.960

\

Figure 3-24. Auto Sweep Menu

,

3-32

SECTION 3

Measurement

3.8 LIGHT CONNECTIONS

A user-supplied light can be connected to the system in

order to help attain device equilibrium in inversion more
rapidly. This light is controlled through appropriate ter­minals on the DIGITAL I/O port of the Model 5951 Re­mote Input Coupler. The following paragraphs discuss
DIGITAL I/O port terminal assignments along with
typical light connections.

3.8.1

Table 3-2 summarizes the terminal assignments for the
DIGITAL I/O port of the Model 5951. Figure 3-25 shows
the pinouts for the supplied mating connector. Terminals
include:

Digital I/O Port Terminals

Table 3-2. Digital UO Port Terminal

Assignments

+5V Digital (pins 1 and 2): +5V digital is supplied
through an internal 33Q resistor for short-circuit protec­tion. Current draw should be limited to 2OmA to avoid
supply loading.

Digital Inputs (pins 3-6): These terminals pass through
the digital inputs to the Model 230-l. One possible use for
these inputs would be to monitor a test fixture closure
status switch. Note that the Model 82.DOS software does
not presently support reading the input terminals, but it

could be modified to do so, if desired. The statuS of these

inputs can be read with the Ul command, as described in

the Model 230 Progmmming Manual.

OUTPUT: OUTPUT is intended for controlling an exter­nal light source. Logic convention is such that OUTPUT
is LO when the software indicates that the light is ON.

Note that OUTPUTis LS-‘ITL compatible with a guaran-

teed 8mA current sink capability.

Digital Common: Provides a common connection for ex­ternal circuits.

*+w SO”rCe through internal 33* resistor.

“Eigital inputs passed through to Model 230-I
‘*‘Output controls light: Hl=OFF; LO=ON

Digital l/O Port

ci

12 11 IO 9 8 7

Figure3-25. Digitdl/OPort Terminal Arrangement

3.8.2 LED Connections

The digital output has sufficient drive capability to di­rectly drive LEDs up to 8mA using the connecting
method shown in Figure 3-26. The anode of the LED
should be connected to +5V, and the cathode should be
connected to OUTPUT through a 33012 current-limiting
resistor. Use of LEDs that draw more than 8mA is not rec­ommended.

3.8.3

For larger LEDs, or for small incandescent lamps, an ex­ternalrelaycontiolcir&tcanbeusedtoswitchthelarger
current. Figure 3-27 shows a typical circuit. With the con­figuration shown, a normally closed relay contact will be
necessary to ensure the light is on at the proper time.
Note that an external power supply wiU be necessary to
drive the external circuitry. The value of the base resistor
will depend on the current gain of the transistor as well as
the power supply voltage and relay coil resistance. For

example, with a supply voltage of 5V, a coil resistance of

500Q, and a current gain of 100, a base resistor value of

lO~shouldbeadequatetodrivethet+ansistorintosatu-

ration.

Relay Control

3-33

SECTTON 3

Measurement

Digital

Common

F

5951

Digital

I/O Port

‘igure 3-26. Direct LED Control

““T

!

=z

=E

output -+f<

F

Digital

1

Lamp

12

Qwe 3-27. Relay Light Control

3-34

3.9 MEASUREMENT CONSIDERATIONS

The importance of making careful C-V curve measure-

ments is often underestimated. However, errors in the
C-V data will propagate through calculations, resulting
in errors in device parameters derived from the curves.

These errors can be amplified during calculations by a

factor of 10 or more.

With careful attention, the effects of many common error
sources can be minimized. In the following paragraphs,
we will discuss some common error sources and provide
suggested methods for avoiding them.

Figure 3-28.

C-VCumewitk Cqmcitance Offset

3.9.1

Theoretically, a capacitance measurement using one of
the common techniques would require only that two
leads be used to connect the measuring instrument to the
device under test (DUT)---the input and output. In prac­tice, however, various parasitic or stray components
complicate the measuring circuit.

Stray Capacitances

Regardless of the measurement frequency, stray capaci­tances present in he circuit are important to consider.
Stray capacitances can cause offsets when they are in par­allel with the device, can act as a shunt load on the input
or output, or can cause coupling between the device and
nearby AC signal sources.

When stray capacitance is in parallel with the DUT, it
causes a capacitance offset, adding to the capacitance of
the device under test (Cow), as shown in Figure 3-28.
Shunt capacitance, on the other hand, often increases the
noise gain of the instrumentation amplifiers, increasing
capacitance reading noise (Figure 3-29). Shunt capaci­tance also forms a capacitive divider with COUT, steering
current away from the input to ground. This phenome­non results in capacitance gain error, with the C-V curve
results shown in Figure 3-30.

Potential Error Sources

Figure 3-29.

C-V Curve with Added Noise

C

-..,,
‘..,

‘..,

\

‘Y,

“X ..._.____I_,__ _ _......

‘I-

. . . . . . .

V

3-35

SECTION 3

Measurement

Stray capacitance may also couple current of charge from
nearby AC signal sources into the input of the measuring
instrument. This noise current adds to the device current
tid results in noisy, or unrepeatable measurements. For
quasistatic measurements, power line frequency and

electrostatic coupling are particularly troublesome,
while digital and RF signals are the primary cause of
noise induced in high-frequency measurements.

Leakage Resistances

Under quasistatic measurement conditions, the imped­ance of Cour is almost as large as the insulation resistance
in the rest of the measurement circuit. Consequently,
even leakage resistances of lo’%2 or more can contribute
significant errors if not taken into consideration.

Resistance across the DUT will conduct an error current
in addition to the device current. Since this resistive cur-

rent is directly proportional to the applied bias voltage,

and the capacitor current is not, the result is a capacitance
offset that is proportional to the applied voltage. The end
result shows up as a “tilt” in the quasistatic C-V curve, as
shown in Figure 3-31.

Stray resistance to nearby fixed voltage sources results in
a constant (rather than a bias voltage-dependent) leakage
current. Other sources of constant leakage currents in­dude instrument input bias currents, and electrochemi­cal currents caused by device or fixture contamination.
Such constant leakage currents cause a voltage-inde­pendent capacitance offset.

Keep in mind that insulation resistance and leakage cur-

rent are aggravated by high humidity as well as by con­taminants. In order to minimize these effects, always
keep devices and test fixties in clean, dry conditions.

High-frequency Effects

At measurement frequencies of approximately 1OOkHz

and higher, the impedance of CDU~ may be so sma!.l that

any series impedance in the rest of the circuit may cause

errors. Whether such series impedance is caused by in­ductance (such as from leads or probes), or from resis-

tance (as with a high-resistivity substrate), this series in­pedance causes non-linearity in the measured capaci­tance. The resulting C-V curve is, of course, affected by
such non-linearity, as shown in Figure 3-32. Note that
Model 82-DOS compensates for series resistance (see
paragraph3.6.3).

..-.-... . . .._____~._.

C

x,,

:..,,

C

,,-- ., /

,/’

./’

?L!I

.._.. _ . ..__........ _. Tilt& Curve Caused by

Figure 3-31. Curve Tilt Cause by Volfage Dependent

Leaakage

336

“..,,, j

;., :

V

Leakage
Normal

“...,J

__,--

,/”

“.,_

. .

. . . . . _ . . . . . . _..._ .,..

1

_..._._____________. With Nonlinearity

Figure 3-32. C-V Curve Caused by Nonlinearity

Another high-frequency effect is caused by the AC net­work formed by the instrumentation, cables, switching
circuits, and the test fixtures. Referred to as transmission
line error sources, the network essentially transforms the
impedanceof Covr when it is referred to the input of the
instrument, altering the measured value. Transmission
line effects alter the gain and produce non-linearities.

V

Normal

SECTION 3

Measurement

3.92

The many possible error sources that can affect C-V
measurements may seem like a great deal to handle.
However, careful attention to a few key details will re­duce errors to an acceptable level. Once most of the error
sources have been
further reduced by using the probes-up suppression and
corrected capacitance features of the Model 82 software.

Key details that require attention include use of proper
cabling and effective shielding. These important aspects
are discussed below.

Cabling Considerations

Cables must be used to connect the instruments to the de­vice under test. Ideally, these cables should supply the
test voltage to the device unaltered in any way. The test
voltage is converted into a current or charge in the DUT,
and should be carried back to the instruments undis­turbed. Along the way, potential error sources must be
minimized.

Avoiding Capacitance Errors

minimized, any residual errors can be

that is lubricated with graphite to reduce friction and to
dissipate generated charges.

Flex-producing vibration should be eliminated at the
source whenever possible. If vibration cannot be entirely
eliminated, cables should be securely fastened to prevent
flexing.

One final point regarding cable precautions is in order:
Cables can only degrade the measurement, not improve
it. Thus, cable lengths should be minimized where possi-

ble, without slmining cables or connections.

Device Connections

Care in properly protecting the signal path should not
stop at the cable ends where the connection is made to the

DUT fixture. In fact, the device connection is an ex-

tremely important aspect of the measurement. For the

same reasons given for coaxial cables, it is best to con-

tinue the coaxial path as close to the DUT as possible by
using coaxial probes. Also, it is important to minimize
stray capacitance and maximum insulation resistance in
the pathway from the end of the coaxial cable to the DUT.

Coaxial cable is usually used in order to eliminate stray
capacitance between the measurement leads. The cable
shield is connected to a low-impedance point (guard)
that follows the meter input. This technique, known as
the three-terminal capacitance measurement, is almost
universally used in commercial instrumentation. The
shield shunts current away from the input to the guard.

Coaxial cables also serve as smooth transmission lines to
cany high-frequency signals without attenuation. For
this reason, the cable’s characteristic impedance should
closely match that of the instrument input and output,
which is usually 5OQ. Standard RG-58 cable is adequate
for~equenciesintherangeofllcHz tomore thanlOMHz.
High-quality BNC connectors with gold-plated center
conductors reduce errors from high series contact resis­tance.

Quasistatic C-V measurements are susceptible to shunt
resistance and leakage currents as well as to stray capaci-

tances. Although coaxial cables are still appropriate for
these measurements, the cables should be checked to en­sure that the insulation resistance is sufficiently high

b1OW. Also, when such cables are flexed, the shield
rubs against the insulation, generating small currents
due to triboelectric effects. These currents can be mini­mized by using low-noise cable (such as the Model 4801)

Most devices have one terminal that is well insulated
from other conductors, as in the gate of an MOS test dot.
The input should be connected to the gate because it is
more susceptible to stray signals than is the output. The
output can better tolerate being connected to a terminal
with high shunt capacitance, noise, or poor insulation re­sistance, although these characteristics should still be op­timized for best results.

Test Fixtore Shielding

At the point where the coaxial cable shielding ends, the
sensitive input node is exposed, inviting error sources to
interfere. Proper device shielding need not end with the
cables or probes, however, if a shielded test fixture is
used.

A shielded fixture, sometimes known as a Faraday cage,
consists of a metal enclosure that completely surrounds
the DUT and leads. In order to be effective, the shield
must be electrically connected to the coaxial shield. Typi­cally, bulkhead connectors are mounted to the side of the
cage to bring in the signals. Coaxial cables should be con­tinued inside, if possible, or individual input and output
leads should be widely spaced in order to maintain in­put/output isolation.

3-37

SECTION 3

Measurement

3.9.3

Controlling errors at the source is the best way to opti­mize C-V measurements, but doing so is not always Pos­sible. Remaining residual errors include offset, gain,
noise, and voltage-dependent errors. Ways to deal with
these error sources are discussed in the following Para-

graph.

Offsets

Offset capacitance and conductance caused by the test
apparatus can be eliminated by performing a suppres­sion with the probes in the up position. These offsets will
then be nulled out when the measurement is made.
Whenever the system configuration is changed, the sup­pression procedure should be repeated. In fact, for maxi­mum accuracy, it is recommended that you perform a
probes-up suppression or at least verify prior to every
measurement.

Gain and Nonlinearity Errors

Gain errors are difficult to quantify. For that reason, gain
correction is applied to every Model 82-DOS measure­ment. Gain constants are determined by measuring accu­rate calibration sources during the cable correction proc­ess.

Nonlinearityisnormallymoredifficult tocorrectforthan
are gain or offset errors.‘The cable correction utility sup­plied with Model 82-DOS, however, provides non­linearity compensation for high-frequency measure­ments, even for non-ideal configurations such as switch­ing matrices.

Correcting Residual Errors

Care must be taken when using the corrected capacitance

feature, however. When the device is in non-equilibrium,

device current adds to any leakage current, with the re­sult that the curve is distorted in the non-equilibrium re­gion. The solution is to keep the device in equilibrium

throughout the sweep by carefully choosing the delay

time.

Curve Misalignment

At times, quasistatic and high frequency cuves may be
slightly misaligned due to gain errors or external factors.
In such cases, curve gain and offset factors can be applied
to the curves to properly align them. This feature is avail-

able under the analysis and graphics menus.

Noise

Residual noise on the C-V curve can be minimized by us-

ing filtering when taking your data. However, the filter
will reduce the sharpness of the curvature in the transi-

tion region of the quasistatic curve depending on the

number of data points in the region. This change in the

curve can cause CQ to dip below CH, resulting in errone-

ous DX calculations. If this situation occurs, bun off the

filter or add more data points.

3.9.4 Interpreting C-V Curves

Even when all the precautions outlined here are fol-

lowed, there are still some possible obstacles to success-

fully using C-V curves to analyze semiconductor devices.

Semiconductor capacitances are far from ideal, so care

must be taken to understand how the device operates.

Also, the curves must be generated under well-con-

trolled test conditions that ensure repeatable, analyzable

results.

Maintaining Equilibrium

Voltage-dependent Offset

Voltage-dependent offset (curve tilt) is the most difficult

to correct error associated with quasistatic C-V measure­ments. It canbe eliminated by using the corrected capaci­tance function of the Model 8%DOS software. In this
technique, the current flowing in the device is measured
as the capacitance value is measured. The current is

known as Q/t because its value is derived from the slope

of the charge integrator waveform. Q/t is used to correct
capacitance readings for offsets caused by shunt resis-

tance and leakage currents.

3-38

The condition of the device when all internal capaci-

tances are fully charged is referred to as equilibrium.
Most quasistatic and high-frequency C-V curve analysis

is based on the simplifying assumption that the device is
measured in equilibrium. Internal RC time constants

limittherateatwhichthedevice biasmaybesweptwhile

maintaining equilibrium They also determine the hold

time required for device settling after setting the bias

voltage to a new value before measuring Cr,vr.

The two main parameters to be controlled, then, are the
bias sweep rate and the hold time. When these parame-

SECTION 3

MtZSU~t?~t?ilt

ters are set properly, the normal C-V -es shown in
Figure 3-33 result. Once the proper sweep rate and hold
time have been determined, it is important that all curves
compared with one another be measured under the same
test conditions; otherwise, it may be the parameters, not
the devices themselves, that cause the compared curves
to differ.

Analyzing Curves for Equilibrium

There are three primary indicators that can be used to de-

termine whether a device has remained in equilibrium

Accumulation Depletion

during testing. First, as long as a device is in equilibrium,

Corrr is settled at all points in the sweep. As a result, it
makes no d.ifference whether the sweep goes from accu­mulation to inversion, or from inversion to accumula­tion, nor does it matter how rapidly the sweep is per­formed. Therefore, curves made in both directions willbe
the same, exhibiting no hysteresis, and any curve made at
aslowerratewillbe thesame. Figure3-34shows the type
of hysteresis that will occur if the sweep rate is too fast,
and the device does not remain in equilibrium.

The second equilibrium yardstick requires that the DC

current through the device be essentially zero at each

Quasistatic

Deep Depletion

44

V substrate

Figure3-33. Normal C-V Curue Results when Device is kept in Equilibrium

High Frequency

A. QUASISTATIC

‘igure 3-34. Curve Hysteresis Resulting When Sweep is too Rapid

B. HIGH FREQUENCY

SECTION 3
MUWWtltVlt

measurement point after device settling. This test can be
performed by monitoring Q/t. Thirdly, the curves
should exhibit the smooth equilibrium shape. Deviations
from the ideal smooth shape indicate a non-equilibrium
condition, as in the examples resulting from too short a
hold time shown in Figure 3-35. Note that at least two of
these indicators should be used together, if possible, be­cause any of the three alone can be misleading at times.

One final quick test to confirm equilibrium is to observe
Ca during a hold time at the end of the C-V sweep from
accumulation to inversion. During this final hold time,
the capacitance should remain constant. If a curve has
been swept too quickly, the capacitance will rise slightly
during the final hold time.

Initial Equilibrium

Biasing the device to the starting voltage in the inversion

region at the beginning of a C-V measurement creates a
non-equilibrium condition that must be allowed to sub­side before the C-V sweep begins. This recovery to equi­librium can take seconds, minutes, or even tens of min­utes to achieve. For that reason, it is generally advanta­geous to begin the sweep in the accumulation region of
the curve whenever possible.

version layer, thus speeding up equilibrium and shorten­ing the hold time.

The best way to ensure equilibrium is initially achieved is
to monitor the DC current in the device and wait for it to
decay to the DC leakage level of the system. A second in­dication that equilibrium is reached is that the capaci­tance level at the initial bias voltage decays to its equilib­rium level.

3.9.5

The dynamic range of a suppressed quasistatic of high­frequency measurement will be reduced by the amount
suppressed. For example, if, on the 200pF range, you
were to suppress a value of IOpF, the dynamic range

would be reduced by that amount. Under these condi-

tions, the maximum value the instrument could measure
without overflowing would be 190pF.

A similar situation exists when using cable correction
with the Model 590. For example, the maximum measur-

able value on the ZnF range may be reduced to I.&F

when using cable correction. The degree of reduction will

depend on the amount of correction necessary for the

particular test setup.

Dynamic Range Considerations

Still, it is often necessary to begin the sweep in the inver-

sion region to check for curve hysteresis. In this case, a
light pulse, shone on the device, can be used to quickly

generatetheminoritycarriersrequiredbytheformingin-

.._ . . . . . . . . . . . . . . . . . Short

A. QUASISTATIC

‘igure 3-35. Curve Distortion when Hold Time is too Short

The dynamic range of quasistatic capacitance measure-

ments is reduced with high Q/t. The maximum Q/t

value for a given capacitance value depends cm both the
delay time and the step voltage. See the Model 595 II­shuction Manual Specifications for details.

1

Hold Time

Normal

6. HIGH FREQUENCY

3-40

SECTION 3

Measurement

3.9.6

Series and Parallel Model
Equivalent Circuits

A complex impedance can be represented by a simple se­ries or parallel equivalent circuit made up of a single re­sistive element and a single reactive element, as shown in
Figure 3-36. In the parallel form of (a), the resistive ele­ment is represented as the conductance, G, while the re­actance is represented by the susceptance, B. The two to­gether mathematically combine to give the admittance,
Y, which is simply the reciprocal of the circuit imped­ance.

Y=G+JB

B = WCP (CAPACITIVE)

OR

B = 1 (INDUCTIVE)

OLP

4) PARALLEL CIRCUIT

‘iawe 3-36. Series and Parallel Imaedances

Z=Fi+JX

X = 1 (CAPACITIVE)

WCS

OR

X = cots (INDUCTIVE)

(5) SERIES CIRCUIT

tor and numerator by the conjugate of the denominator
as follows:

R + jX=‘x-

Performing the multiplication and combining terms, we
have:

If we assume the reactance is capacitive, we can substi­tute -1 /WC, for the reactance and WC, for the susceptance
(C, is the equivalent series capacitance, and C, is the
equivalent parallel capacitance). The above equation

then becomes:

R-jX

-=

In a lossless circuit (Rand G both O), C, and C, would be
equal. A practical circuit, however, does have loss be­cause of the finite values of R or G. Thus, C, and C, are not
equal--thegreaterthecircuitloss,thelargerthedispality

between these two values.

Series and parallel capacitance values can be converted to
their equivalent forms by taking into account a dissipa­tion factor, D. D is simply the reciprocal of the Q of the ti­cuit. For a parallel circuit, the dissipation factor is:

R+jX=---

WCS

G+jB G-jB

G2 + 3Cp2

G-jB

G-jB

G2+82

G - joCp

In a similar manner, the resistance and reactance of the
series form of (b) are represented by R and X, respec­tively. The impedance of the series circuit is 2.

The net impedances of the equivalent series and parallel
circuits at a given frequency are equal. However, the in­dividual components are not. We can demonstrate this
relationship mathematically as follows:

R+jX=L

To eliminate the imaginiuy form in the denominator of

the right-hand term, we can multiply both the denomina-

G + jB

“=$=S

For the series circuit, the dissipation factor is defined as:

D=+C,R

By using the dissipation factor along with the formulas
summarized in Table 3-3, you can convert from one form
to another. Note that C, and C, are virtually identical for
very small values of D. For example, if D is 0.01 Land C,
are within 0.01% of one another.

Example:

Assume that we make a 1OOldlz measurement on a par&
lel equivalent circuit and obtain values for C, and G of

P

3-41

SECTION 3

Model

Table 3-3.

Equivalent Circuit

Converting Series-parallel Equivalent Circuits

I

Xssipation Factor

G

Parallel, CP, G

CP

Series C, R

D=lL2-

Q WC,

D=;=wC,R

1

16OpF and 30@ respectively. From these values, we can
calculate the dissipation factor, D, as follows:

D=

h(100 x 103) (160 x 101*)

D = 0.3

30 x 10”

Capacitance
Conversion

C,=(1+D2)Cp

c, =A

1+IY

The Model 82-DOS software determines the displayed
value of l&m by converting parallel model data from
the Model 590 into series model data. The resistance

value corresponding to the maximum high-frequency ca­pacitance in accumulation is defined as Rmm See para­graph 3.9.6 for a detailed discussion of parallel and series
model.

R= D=

(l+@)G

G= D*

(l+D?)R

The equivalent series capacitance is then calculated as
follows:

c, = (1 .t 0.09) 160pF

C, = 174.4pF

3.9.7

Series Resistance

Devices with high series resistance can cause measure­ment and analysis errors unless steps are taken to com­pensate for this error term. The high dissipation factor
caused by series resistance can cause errors in Cm meas­urement, resulting in errors in analysis functions (such as
doping concentration) that use Cm for calculations.

The Model 82-DOS software uses a three-element model
to compensate for series resistance (see Figure 4-10). The
series resistance, Rmms, is an analysis constant that can
be determined using the procedure covered in paragraph

3.6.3. The default value for Rsnu~s is 0, which means that
data will be unaffected if the value is not changed.

Device Considerations

Device Structure

The standard analysis used by Model 8%DOS assumes a

conventional MIS structure made up of silicon substrate,

silicon dioxide insulator, and aluminum gate material.
You can change the program for use with other types of
materials by modifying the MATEFJIALCON file, as dis-

cussed in Appendix A. For compound materials, a

weighted average of pertinent material constants is often

used. Typical compound materials include silicon nitide

and silicon dioxide in a two- or three-layer sandwich.

Device Integrity

In order for analysis to be valid, device integrity should

be checked before measurement. Excessive leakage CUT-

rent through the oxide can bleed off the inversion layer,

causing the device to remain in nonequilibrium indefi­nitely. In this situation, the inversion layer would never
form completely, and Cm measurements would be inac-

curate.

DeviceintegritycanbeverifiedbymonitoringQ/tlevels.
If Q/t levels are excessive, device integrity is suspect.

3-42

3.9.8

Light Leaks

High-quality MOS capacitors, which are the subject of

C-V analysis, are excellent light detectors. Consequently,
care should be taken to ensure that no light leaks into the
test fixture or probe station. Typical areas to check in­clude door edges and hinges, tubing entry points, and
connectors or connector panels.

Test Equipment Considerations

Thermal Errors

Accurate temperature control is important for accurate
C-V data. For example, the intrinsic carrier concentration,
m, doubles for every 8°C increase in ambient tempera­ture. In order to minimize the effects of thermal errors,
keep the device at a constant temperature during meas-

urement, and repeated measurements should a!J be

made at the same temper&me.

If you change the measurement temperature, update the
MATERIAL.CON file for correct values for T and m (see
Appendix A).

3-43

SECTION 4

Analysis

4.1 INTRODUCTION

This section covers the various analysis features of the
Model 82-DOS software. References and suggested read­ing are also included at the end of the section.

Information concerning equipment setup and measure­ment techniques may be found in Sections 2 and 3.

Section 4 information is arranged as follows:

4.2 Constants and Symbols Used for Analysis: Dis­cusses the numerical constants and mathematical
symbols used in this section and by the Model
82-DOS software.

4.3 Obtaining Information from Basic C-V Curves:
Details howtoobtainimportantinformationsu~as
device type and Cm from C-V curves.

4.4 Analyzing C-V Data: Discusses loading/saving
data and displaying data.

4.5 Analysis Constants: Covers displaying analysis
constants and discusses calculation of constants.

4.6 Graphical Analysis: Details graphing of data in­cluding measured and calculated data.

4.7 Mobile Ionic Charge Concentration Measure­ment: Discusses two methods to measure the mo­bile ionic charge concentration in the oxide of an
MOS device.

4.8 References and Bibliography of C-V Measure­ments and Related Topics: Lists references used in
this section, along with additional texts and papers
for suggested reading on C-V measurement and
analysis topics.

4.2 CONSTANTS AND SYMBOLS USED

FOR ANALYSIS

4.2.1

Constants used by the Model 82-DOS software are de­fined for silicon substrate, silicon dioxide insulator, and
aluminum gate material. These constants are defined in
the MATERIALCON file, which can be modified for
usedwithothermaterialtypes (seeAppendixA1. Default
material constants are summarized in Table 4-1.

Default Constants

4-1

SECTION 4

Table 4-1. Default Material Constants

Symbol

nr

Wm

x

*See MATERIAL.CON file for description (Appendix A).

Description

Electmn charge (COIL)
Boltzmann’s constant (T/OK)
Test temperature (“K)
Permitivity of oxide (F/cm)
Semiconductor permittivity (F/cm)
Semiconductor energy gap (eV)
Intrinsic carrier concentration (1 /cm?
Metal work function (V)
Electmn affinity (V)

4.2.2 Raw Data Symbols

The following symbols are used for data measured and
sent by the Models 590 and 595. CQ’ is interpolated from

CQ so that CQ’ and CH are values at the same bias voltage.

CH

CC!

G

Q/t

VH Voltage reading sent by Model 590 with

High-frequency capacitance, as meas­ured by the Model 590 at either 1OOkHz
or IMHZ.

Quasistatic capacitance measured by the
Model 595. CQ is interpolated from CQ’ so
that CQ’ and CH are values at the same
bias voltage

High-frequency conductance, as meas­ured by the Model 590 at either 1OOkHz
or IMHZ.

Current measured by the Model 595 at
the end of each capacitance measure­ment with the unit in the capacitance

function.

matching CH and G.

Cd

CHA

CMN

COX

Dm

EC

ET
NA
ND
NAVG

Default Value

1.60219 x lo-l9 Cal.

1.38066 x lo-= J/OK

293°K

3.4 x lO-‘I F/cm

1.04 x lG-‘2F/cm

1.12eV

1.45 x 1O’O cm3

4.1v

4.15v

ues. CQA is the value that is actually plot­ted and printed.

Interpolated V&e Of CQ set to Corre­spond to the quasistatic capacitance at V.

The high-frequency capacitance that is
adjusted according to gain and offset val­ues. CHA is the value that is actually plot­ted and printed.

Minimum high-frequency capacitance in
inversion.

Oxide capacitance, usually set to the
maximum CH in accumulation.

Density or concentration of interface
states.

Energy of conductionband edge (valence
band is Ev).

Interface trap energy.
Bulk doping for p-type (acceptors)
Bulk doping for n-type (donors)
Average doping concentration.

4.2.3

Calculated data used by the various analysis algorithms
include:

A
CFB

CQA

4-2

Calculated Data Symbols

Device gate area.

Flatband capacitance, corresponding to
no band bending.

The quasistatic capacitance that is ad­justed according to gain and offset val-

NkW.K
NEIF
N(90% Wwx)

NM

QEFF

l-csP.E
tax

Bulk doping concentration.
Effective doping concentmtion.
Doping corresponding to 90% maximum

w profile (approximates doping in the
bulk).

Mobile ion concentration in the oxide.
Effective oxide charge
Series resistance
Oxide thickness.

SECTION 4

Advsis

VFB

VCS

VTHXISHOLO

w

A(i)

Flatband voltage, or the value of VGS that

results in cm
Gate voltage. More specifically, the volt-

age at the gate with respect to the sub­strate.

The point where the surface potential, I+,
is equal to twice the bulk potential, @B.

Depletion depth or thickness. Silicon un­der the gate is depleted of minority carri­ers in inversion and depletion.

An intermediate value used in cakula­tions.

Silicon surface potential as a function of
VCS. More precisely, this value represents
band bending and is related to surface
potential via the bulk potential.

Offset in vs due to calculation method
and Vo.

Silicon bulk potential.
Extrinsic Debye length.

4.3 OBTAINING INFORMATION FROM BASIC C-V CURVES

Much important information about the device under test

can be obtained directly from a basic C-V curve. Such in­formation includes device type (p- or n-type material)
and COX (oxide capacitance). These aspects are discussed
in the following paragraphs.

4.3.1 Basic C-V Curves

Figure 4-l and Figure 4-2 show fundamental C-V curves
for p-type and n-type materials respectively. Both high­frequency and quasistatic -es are shown in these fig­ures. Note that the high-frequency curves are highly
asymmetrical, while the quasi&tic -es are almost
symmetrical. Accumulation, depletion, and inversion re­gions are also shown on the curves. The gate-biasing po­larity and high-frequency curve shape can be used to de­termine device type, as discussed below.

Capacitance

I

-v GS

Figure 4-1. C-V Characteristics of p-hJpe Material

: :

“FE “THRESHOLD +“GS

GATE BIAS VOLTAGE, V G s

*

4-3

SECTION 4

Capacitance

CMIN

‘“GS “THRESHOLD “FB

Accumulation

b

+“Gs

GATE BIAS VOLTAGE, V G s

Figure 4-2.

C-V Cfuracteristics of n-type Material

4.3.2 Determining Device Type

The semiconductor conductivity type (p or n dopant
ions) can be determined from the relative shape of the
C-V curves. The high-frequency curve gives a better indi­cation than the quasistatic curve because of its highly
asymmetrical nature. Note that the C-V curve moves
from the accumulation to the inversion region as gate
voltage, VGS, becomes more positive for p-type materials,
but the curve moves from accumulation to inversion as
VGs becomes more negative with n-type materials (Nicol­lian and Brews 372-374).

lnorderto determine thematerialtype,usethefollowing

rules:

1. IfC~is greaterwhenV~siSnegativethanwhenVcsis
positive, the substrate material is p-type.

2. If, on the other hand, CX is great&r with positive VGS
than with negative VGS, the subs&&e is n-type.

3. The end of the curve where CH is greater is the accu-

mulation region, while the opposite end of the curve
is the inversion region. The transitional area be­tween these two is the depletion region. These areas
are marked on Figure 4-1 and Figure 4-2.

4.4 ANALYZING C-V DATA

A number of operations can be performed on sweep data
stored in a reading array including: saving or loading
data to or from disk, displaying or printing reading data,
graphing or plotting reading data, as well as mathemati­cal analysis of doping profile, flatband calculations, and
interface traps. The following paragraphs discuss analy­sisoperationsavailablewiththeModel82-DOSsoftware.

NOTE
You can start the program with analysis by
specifying a data file when running the pm­gram. See paragraph 2.4.9 for details.

4.4.1 Plotter and Printer Requirements

Aplotterorprintercanbeconnected totheserialorpaml­lel port, or to the IEEE-488 bus (plotter only) to obtain
hard copy graphs. Paragraph 2.4 discusses recom-

mended plotters and printers, as well as how to define
the equipment during installation or reconfigumtion.

4-4

** SWEEP DATA ANALYSIS **

1. Save Measurement Data Array to File

2. Load Measurement Data Array from File

3. Display Data Arrays

4. Display Analysis Constants

5. Graph Quasistatic C vs. Gate Voltage

6. Graph High Frequency C vs. Gate Voltage

7. Graph Both Cq and Ch VS. Gate Voltage

8. Graph Q/t Current vs. Gate Voltage

9. Graph Conductance vs. Gate Voltage

10. Graph Doping Profile vs. Depth

11. Graph Ziegler Doping Profile vs. Depth

12. Graph Depth vs. Gate Voltage

13. Graph l/Ch-2 vs. Gate Voltage

14. Graph Dit vs. Energy

15. Graph Band Bending vs. Gate Voltage

16. Graph Quasistatic C vs. Band Bending

17. Graph High Frequency C vs. Band Bending

18. Return to Previous Menu

SECTION 4

Analysis

Enter number to select from menu :

Figure 4-3. Data Analysis Menu

4.4.2 Analysis Menu

FigureP3showstheanalysismenu.Youcanaccessthis
menueitherbyseledingoption5,AnalyzeC-VData,on

l Displaying or modifying numerical constants such as

l Graphing or plotting reading array data.
l Graphical and mathematical analysis of the data array.

themainmenu,orthroughmostothersubmenus.

Keyoperationsavailableonthemenuinclude:

4.4.3

COX, tax, and N (doping concentration).

Saving and Recalling Data

l Savingorloadingreadingandgraphicsarraydatato

orfromdisk.

l Displaying (CRT) or printing (external printer) read-

ing or graphics array data.

By selecting option 1 or 2 you can save the current read­ing and graphics arrays to diskette, or load previous data

into the reading arrays. See Appendix I for data format

details.

4-5

NOTE
Loadingdatafromdiskettewilloverwriteany
data currently stored in the reading and
graphics arrays. Data analysis and graphing is
always carried out using data currently stored

in the reading or graphics arrays.

Saving the Data

2.

At the prompt, type in the desired filename and
press ENTER (specify the complete path if file is on a
different drive or directory). You need not specify
the .DAT extension.
If the file exists, the arrays will be filled with the data

3.
from the file; however, an error message will be
given if the file does not exist, or ifit is of the wrong

type,

4. To return to the analysis menu, press ENTER.

Use the following procedure to save sweep and graphics
data presently stored in memory.

1.

Select option 1 on the analysis menu.

2.

The computer will display the current disk direc­tory.

3.

Youwillthenbeprompted totypein thedesiredfile­name. Besure to~ooseanamenotonthepresent di­rectory. Also, you need not type in the file extension

(.DAT). You can also use the full path name to spec-

ify another directory or disk drive (for example,
A:MwrLE 0r c: \PATH\MYFJLE).

4.

Next you will be prompted to enter two lines of

header information, up to amaximum of 160 charac­ters. This feature can be used to enter important in­formation about the data you are saving. For exarn-

ple, you may wish to enter the type of device, the

date, and the time the data was takenforfutierefer­ewe.

5.

After entering header information, you will be given

one last opportwity to change it.

6.

Next, you will be prompted to choose one of the fol-

lowing data delimiters: comma, space or tab. This
feature allows you to choose a file format compatible
with other programs such as spreadsheet programs

(you can use any of the three delimiters for Model
82-DOS file operations).

7.

Once you have chosen the delimiter, the data file will
be saved.

NOTE

Refer to Appendix I for information on im-

porting data into other programs.

4.4.4 Displaying and Printing the
Reading and Graphics Arrays

By selecting option 3 on the Sweep Data Analysis menu,
you can display array data on the computer CRT or print

out that array data for hardcopy. In order to print the
data, you must, of course, have a printer connected to the

computer. When displaying array data, the screen wiIl be

cleared before arrays are displayed.

Note that you can display or print either reading or

graphics array data by selecting the appropriate option

on the submenu. The displayed and printed reading ar­ray data includes the reading number; quasistatic capad­tance, current (Q/t); and high-frequency capacitance,
conductance, and gate voltage. An example is shown in
Figure 4-4.

NOTE
The quasistatic and high-frequency capaci­tance values that are plotted, printed, and
used in calculations are first corrected for gain
and offset (paragraph4.4.7) to obtain C~A and
CHA (adjusted capacitance).

Graphics array data includes depletion depth, doping

concentration, band bending, interface trap energy, 1 /C2,
and interface trap density. An example is shown in
Figure 4-5. Ziegler (MCC) doping and depth are dis­played separately, as shown in Figure 4-6.

Loading Data

Use the procedure below to recall data from disk and
store it to the reading and graphics arrays. Remember
that any data presently in the reading and graphics ar­rays wiU be overwritten by the data loaded from disk.

1. Select option 2 on the analysis menu. The computer
will then display the current disk directory,

4-6

NOTE
Values of 103* “flag” invalid data as explained
in paragraph 4.4.8.

When displaying data on the CRT, you have the option of
seleaing the first reading number to display.

To print out only a portion of the array, display that por­tion on the screen, then press the PRINT SCREEN key.

SECTION 4

Analysis

/

Rdg#

Press ENTER to continue or enter a reading number. Enter Q to quit: :

Q/t (PA) G (us)

1 -l.aOOOE-01 +l.lOOOE+OO +2.4972E+02 +2.50603+02
2 -1.8000E-01 +l.lOOOE+OO +2.5019E+02 +2.5050Et02
3 -1.8000E-01 +l.lOOOE+OO +2.5041E+02 +2.5050Et02

4 -1.8000E-01 +1.1000E+00 t2.5054Et02 +2.5040Et02
5 -1.8000E-01 +1.1000E+OO t2.5061Et02 t2.5040Et02
6 -1.8000E-01 +1.1000E+00 +2.5071Et02 t2.5030Et02
7 -1.8000E-01 +1.1000E+00 t2.5063Et02 t2.5040Et02
8 -1.9000E-01 +1.1000E+00 t2.5045Et02 +2.50203+02
9 -2.OOOOE-01 t1.1000Et00 t2.5019Et02 t2.5010Et02

10 -2.OOOOE-01 +1.1000Et00 t2.5014Et02 t2.5020Et02

cq (pF)

Ch (pF)

v!+!s

i.5.840
t5.740
t5.640
t5.540
t5.440

t5.340
t5.230
+5.140
t5.030
t4.930

Figure 44.

Selecting the Graphics Range

The graphics range defines the array limits to be plotted.
To change the graphics range, (select graphics range) se-

lect option 3 on the analysis menu, then option 7 on the
subsequent menu. The present graphics range alongwith

best depth and total army size will be displayed. Key in

the first and last readings at the corresponding prompts.

Example of Reading Array Print Out

One particularly good use for this feature is to select the
range for best depth. The range over which N and Drr are
accurate to within zk5% is equal to best depth The graph­its range can also be used to zoom in on interesting sec­tions of other -es.

4-7

SECTION 4
Analusis

/

Rdg#

Psi6 (V) Et (eV) Dit(l/cm^2eV)

1 +1.7358E-01 +4.5049E-01 t2.5688Et18

2 +1.7342E-01 +4.5032E-01 -2.9719Et14

3 +1.73343-01 +4.5025E-01 -1.8995Et14
4 +1.7332E-01 +4.5022E-01 t4.4032Et14
5 +1.7332E-01 +4.5023E-01 -3.8293Et15
6 +1.7337E-01 +4.5027E-01 -4.8509Et14
7 +1.7338E-01 +4.502&?E-01 -1.9160Et15

8 +1.7331E-01 +4.5022E-01 t1.5670Et14

9 +1.7315E-01 +4.5005E-01 t1.6423Et13

10 +1.72963-01 +4.4987E-01 -1.3387Et13

Press ENTER to continue or enter Q reading number. Enter Q to quit :

\

Figure 4-5.

4-8

Emmple of Graphics Array Print Out

/

--- Ziegler ----

Rdgt/

2 +1.6565E-04 tl.OOOOEt32 +1,6565E-04 tl.OOOOE+32 +1.5936E-05

4 +3.3146E-04 tl.OOOOEt32 +3.31468-04 tl.OOOOE+32 +1.59495-05
5 +3.3146E-04 -5.0791Et16 +3.1218E-04 -1.6930E416 +1.5949E-05

7 +3.3146E-04 -5.4602Et16 +3.0109E-04 -1.8201Et16 +1.59491-05
8 +6.6348E-04 +3.9755Et17 tl.l158E-04 t1.3252Et17 +1.5974E-05

10 +6.6348E-04 t1.0880Et18 +6.7450E-05 t3.6266Et17 +1.5974E-05

w (urn) N (cm*-3) ” (urn)

N (cm*-3)

1 -3.3636E-08 -5.4132Et22 -3.3636E-08 -5.4132Et22 +1.5923E-05

3 +1.6565E-04 t1.8272Et18 +5.2048E-05 t6.0907E+17 +1.5936E-05

6 +4.9740E-04 +3.8183E+17 +1.1386E-04 t1.2728Et17 +1.5962E-05

9 +8.2969E-04 -7.7665E+17 +7.9833E-05 -2.5888Et17 +1.5987E-05

SECTION 4

Analvsis

1 /Ch’2

Press ENTER to continue or enter a reading number. Enter Q to quit :

\ 1

Figure 4-6. Example of Ziegler (MCC) Doping Array Print Out

4-9

SECTION 4

Analysis

4.5 ANALYSIS CONSTANTS

Table4-2 summarizes analysis constants. These con­stants are covered in detail in the following paragraphs.

Constants that can be changed include:

1. IzmE

2. Cox and tax or Area

3. NBULK

4. chm

Table 4-2. Analysis Constants

I Constants

COX
RSWES
NBULK
CFB

VlXR?SHOLD

tax
Cm

00

VFB
NEFF
Area
NAVG
h
Wh15

Menu Term

COX
Rseries

Nbulk

Cfh

Vthresh

tax

Chill
PhiB
Vfb
Neff
Area
Navg
Lb
Work Fn
Qeff
DevType
Best depth

1 ;;zg,;Ege

Minimum capacitance
Bulk doping
Flatband voltage
Effective oxide charge concentration
Gate area

Average doping concentration
Extrinsic Debye length
Work function difference
Effective oxide charge
Device type
Best depth

To change these constants, select option 1 (Change con­stants) on the analysis constants menu (see Figure 4.7),
and type in the desired values when prompted to do so.
Constants that can be changed are discussed in para­graphs 4.5.1 through 4.5.4. Calculations for many other
constants are discussed in subsequent paragraphs.

4-10

SECTION 4

Analysis

/

*** Analysis Constants ***

Rseriee(ohms):+4,400OE-01

Menu: 1) Chance constants 2) Gain/Offset 3) Print 4) Exit

Enter number to select from menu :

Cox(pF):+2.5060E+02 tox(nm):+1.3567E+02

Nbulk(cm'-3):+8.4000E+l4

Cfb(pF):+l.8749E+02 Vfb(V):-3.9316E-01

Vthresh(V):-1.4438E+OO Neff(l/cm-2):+9,3945E+09 Qeff(coul/sm^2):+1.5052E-09

Best depth(w): +4.1905E-01

Cq gain:+l.OOOOE+OO
Ch gain:+I.OOOOE+OO

Cmin( F):+7.3700E+Ol

7

PhiB V):+2.7690E-01

DevType: II

I- to --

Cq offset( +O.OOOOE+OO
Ch offset( +O.OOOOE+OO

+9.2515E-01

Area~cm~2~:+1.0000E-02

Navg(cm^-31:+1,3654E+l9

Lb(um):+1.396fJE-01

Work Fn(V):-3.3310E-01

\

Figure 4-7.

Analysis Constants Display

4-11

SECTION 4

4.5.1 Oxide Capacitance, Thickness,
and Area Calculations

The oxide capacitance, Cox, is the high-frequency capaci­tance with the device biased in strong accumulation. The
value of COX can be determined using the procedure out­lined in paragraph 3.6.3.

Oxide thickness is calculated from Cm and gate area as

follows:

Where:

tax = oxide thickness (nm)
A = gate area (c.m2)
EOX= permittivity of oxide material (F/cm)
COX = oxide capacitance (pF)

The above equation can be easily rearranged to calculate
to solve for gate area if the oxide thickness is known.

Note that E ox and other constants are defined in the MA­TERIAL.CON file and are initialized for use with silicon

substrate, silicon dioxide insulator, and ahuninum gate
material. See Appendix A for information on changing
these constants for use with other materials.

4.5.2

The series resistance, RERE, is an error term that can

cause measurement and analysis errors unless this series
resistance error factor is taken into account. The value of
RSEKE can be determined empirically using the proce­dure discussed in paragraph 3.6.3.

Without series compensation, capacitance can be lower

than normal, and C-V curves can be distorted: Compare

the mcompesated C-V curve in Fime 48 with the com­pensated c&e in Figure 49.

Series Resistance Calculations

I

?gigure 4-8.

110.0

Vth

Vfb

88.4

45.2

GATE VOLTAGE (V)

G-V Cum without Series Resistance Compensation (RSERIES zXXX2J

4-12

SECTION 4

Analysis

‘igure 4-9.

30.00

Vth Wb

24.02

12.06

GATE VOLTAGE (V)

GV Curve with Series Resistance Compensation (RSERIES 3XX2)

The Model 82-DOS software compensates for series resk­tance using the simplified three-element model shown in
Figure 4-10. In this model, Cm is, of course, the oxide ca­pacitance while CA is the capacitance of the accumulation
layer. The series resistance is represented by F&m.s.

R.SERIES

A. Equivalent Three Element

Model of MOS Capacitor
in Strong Accumulation

6. Simplified Model of
f;,“,s;t 10 determine

Figure 4-10. Simplified Model used to Determine

Series Resistance

From Nicollian and Brews 224, the correction capaci­tance, Cc, and corrected conductance, CG, are calculated
as follows:

Gc =(G’M + w2 CL) a

a*+oPcf,g

Where: a = G,., - (G’M + 09 CL) &-

Cc = series resistance compensated parallel
model capacitance
CM = measured parallel model capacitance
Gc = series resistance compensated conduc­tance
GM = measured conductance
RSERES= series resistance

4-13

SECTION 4

4.5.3

Nmx is one of the analysis constants that can be entered.
To change this value, select option 1, Change constants,
and enter the requested values at the corresponding
prompts. Typically, NA or No will be entered using this
function. Note that the graphics arrays will be recalcu-

lated if Nmx is changed.

4.6.4

Cm is the value of high-frequency capacitance with the
device biased in strong inversion. The Cm is one of the
constants used to calculate NAVG, and its value can be de­termined using the procedure outlined in paragraph

3.6.4.

To enter a new Cm value from the analysis constants
menu, select option 1, Change constants, and enter the
value at the appropriate prompt.

Changing NBULK

Changing CMIN

CFB is calculated as follows:

cm=

Where: Cm = flatband capacitance (pF)

Cox = oxide capacitance (pF)

ES = permittivity of substrate material (F/cm)
A = gate area (cm21
1 x lcs-4 = units conversion for h
1 x lo-I2 = units conversion for COX

And h = extrinsic Debye length =

Where: kT = thermal energy at rmm temperature

(4.046 x lO”lJ)
q = electron charge (1.60219 x 10-‘gcoul.)

Nx=Nat90%W~~,orN~orN~wheninputby
the user.

cox ESA/(lX104)(h)

(lxlO=)(cOx)+ E5A/(lXlO~)(h)

(1x104) (@g "2

4.5.5

Flatband Capacitance and
Flatband Voltage

Model 82-DOS uses the flatband capacitance method of
finding flatband voltage, Vm. The Debye length is used to
calculate the ideal value of flatband capacitance, CFB,
once the value of cm is known, the value of VFB is inter­polated from the closest VCS values (Nicollian and Brews
487-488).

The method used is invalid when interface trap density
becomesvelylarge (10’2-10’3and greater). However,this
algorithm should give satisfactory results for most users.

Those who are dealing with high values of Drr should

consult the appropriate literature for a more appropriate
method and modify the Model 82-DOS software accord­ingly.

Based on doping, the calculation of CFB uses N at 90%
WMAX, or user-supplied NA (bulk doping for p-type, ac­ceptors) or ND (bulk doping for n-type, donors).

N at 90% WP.UX is chosen to represent bulk doping.

To change the value of N to NA or ND, select option 1,
Change constants, then enter the new value as NBLLK.

4.5.6

The threshold voltage, VTHRES~OLD, is the point on the C-V

curve where the surface potential vs, equals twice the

bulk potential, 9s. This point on the curve corresponds to

the onset of strong inversion (see Figures 4-l and 4-Z). For
an enhancement mode MOSFET, VTHRESHOLD corresponds

to the point where the devicebegins to conduct. Note that
threshold voltage is displayed as Vt on graphs that plot
vcs on the x axis.

VIHRISHOLD is calculated as follows:

Threshold Voltage

4-14

SECTION 4

Analysis

Vnmmmo = threshold voltage (V)

A = gate area (cn?)
Cm = oxide capacitance (pF)
10’2 = units multiplier
ES = permittivity of substrate material
q = electron charge (1.60219 x lC+’ coul.1

Nmx = buIk doping (cm-?

$B = bulk potential (V)
Vm = flatband voltage (V)

4.5.7

Metal Semiconductor Work
Function Difference

Themetalserniconductorworkfunctiondifference, Wm,
is commonly referred to as the work fundion. It contrib­utes to the shift in Vm from the ideal zero value, along
with the effective oxide charge (NicolIian and Brews
462477, Sze 395-402). The work function represents the
difference in work necessary to remove an electron from
the gate and from the substrate, and it is derived as fol­lows:

W,.,s = -0.95V. Also, for the same gate and n-type silicon
(NBULK = 10%n4), Wm =-0.27X’.

NOTE
Model 82-DOS can be modified for use with
materials other than silicon, silicon dioxide,
and aluminum. See Appendix A for details.

4.5.8 Effective Oxide Charge

The effective oxide charge, Qx+, represents the sum of ox­ide fixed charge, QF, mobile ionic charge, Qw and oxide
trapped charge, Qor. Qm is distinguished from interface
trapped charge, Qrr, in that Qn varies with gate bias and
QEFF = QF + QM + Qor does not (NicoIIian and Brews
424-429, Sze 390-395). Simple measurements of oxide
charge using C-V measurements do not distinguish the

three components of GE. Thesethree components canbe
distinguished from one another by temperature cycling,

as discussed in NicoUian and Brews, 429, Fig. 10.2. Also,
since the charge profile in the oxide is not known, the
quantity, QEFF should be used as a relative, not absolute
measure of charge. It assumes that the charge is located in

a sheet at the silicon-silicon dioxide interface. From
Nicollian and Brews, Eq. 10.10, we have:

Where: WM = metal work function

Ws = substrate material work function (elec-

tron affinity)
Ec = substrate material bandgap
I$B = bulk potential

For silicon, silicon dioxide, and aluminum:

So that,

Wm = -0.61+ b

Wm=-0.61-(y)ln(*)(DopeType)

Where, Dope Type is +1 for p+ype materials, and -1 for
n-typematerials. Forexample,foranMOScapacitorwith
an aluminum gate and p-type silicon (NBUU( = 10’%m3),

vm-wpr(s=--

QEFF

Gx

Note that Cox here is per unit of area. So that,

Qm= A

However, since Cox is in F, we must convert to pF by mul­tiplying by 1P2 as foIlows:

QEm = 10”2cox(wMs - VFB)

Where: Qm = effective charge (cd/cm?

Cm = oxide capacitance (pF)
Wm = metal semiconductor work function (V)
A = gate area (cm*)

Forexample,assumea0.01cm250pFcapacitorwithaflat­band voltage of -5.95V, and a p-type NBULK = 10’6crr-3 (re-

COX(WMS - V,)

A

4-15

SEC’ITON 4

Analysis

sulting in Wm = -0.95V). Such a capacitor would have a
Qm = 2.5 x lO+ coul/cm*.

4.5.9

Effective Oxide Charge
Concentration

The effective oxide charge concentration, NE, is com­puted from effective oxide charge and electron charge as
follows:

NEmF=QEEF

Where:

For example, with an effective oxide charge of 2.5 x
10-8coul/cm2, the effective oxide charge concentration is:

NEFI = effective concentration of oxide charge

(Units of charge/cm2)
Qm = effective oxide charge (coul./cn+)
q = electron charge (1.60219 x 10-‘2coul.)

4

Cw = maximum measured high-frequency
capacitance
CMIN = minimum high-frequency capacitance
(as determined using procedure in paragraph

3.6.4)

The above equation cannot be explicitly solved, and its
solution is only approximate. To obtain the approximate
solution, the Model 82 software performs a binary search
in the range of lO’O< N < 10zO. The search begins at the end
points and takes an average of the two results to deter­mine a test value for N. The error is then calculated as fol­lows:

Since the average doping concentration equation above
has no closed form solution for NAVG, the equation is
solved by minimizingtheerrorintheinterval~~mlO’~to
102O. A 0.01% criteria is used with an upper limit of 100 it­erations.

N

EFF=

Nm = 1.56 x 10” units/cm*

2.5 x lo8

1.60219 x 10-

4.5.10 Average Doping Concentration

The average doping concentration, NAVG, is displayed on
the analysis constants menu. Navy is calculated as fol­lows:

Where:

NAVG = average doping concentration
m = intrinsic carrier concentration of material
used
q = electron charge (1.60129 x 10-‘9coul.)
ES = permittitity of substrate material
tax = oxide thickness (cm)
k = Boltzmann’s constant (1.38066 x 10.=JZIJ/OK

T = test temperature (“K)

EOX = permittivity of oxide material

NOTE

Correct calculation of NAVC requires that CUMIN

be properly determined. C~mr is the high-fre-

quency capacitance value with the device bi­ased in strong inversion, and the value of Cm
can be determined using the procedure dis­cussed in paragraph 3.6.4. Accurate Cm also
depends on proper values for tax and/or area.

4.5.11 Best Depth

The calculated values of N and Dnhave nominal error of
&5% when the depletion depth, w, falls within the fol­lowing limits:

Where: h = extrinsic Debye length

w = depletion depth (km)
Nx = N at 90% Wwx, NA, or No
111 = intrinsic carrier concent+ation

This accuracy range is displayed as best depth on the
analysis constants menu. To set the graphics range to best

4-16

SECTION 4

Analysis

depth, select option 3, display data arrays on the analysis
menu, then select option 7, select graphics range. Type in
the graphics range values equal to the displayed best
depth values.

4.5.12 Gain and Offset

Option 2 on the analysis constants menu allows you to
change gain and offset values applied to CQ and CH data.

Gain and offset can be applied to these data to allow for

curve alignment or to compensate for measurement er­rors. A gain factor is a multiplier that is applied to all ele­ments of Co or CX array data before plotting or graphics
array calculation, and offset is a constant value added to
or subtracted from all CQ and CH data before plotting or
array calculation. The adjusted capacitance values are
called CQA and CHA, and all gain/offset-compensated
readings are indicated as such on the computer screen.

For example, assume that you compare the CQ and Cn
values at reading #3, and you find that CQ is 2.3pF less
than CH. If you then add an offset of +2.3pF to Co, the CQ

and C~valuesatreading#3willthenbethesame,andthe
Ca and CH curves will be aligned at that point.

Gain and offset values do not affect raw CQ and CH values
stored in the data file, but the gain and offset values will
be stored in the data file so that compensated curves can

easily be regenerated at a later date.

To disable gain, program a value of unity (1). Similarly,
program a value of 0 to disable offset.

4.6 GRAPHICAL ANALYSIS

4.6.1 Analysis Tools

Table 4-3 summarizes the graphical analysis tools avail­able with Model 82-DOS. To generate an analysis graph,
select the corresponding option from the analysis menu,
then use the graphics control menu discussed in para­graph 4.6.2 to tailor the graph as required.

Table 4-3. Graphical Tools

Plot (Y vs. X)

CQ vs. VGS Quasistatic capacitance vs. gate voltage
CH vs. VGS
CQ + CH vs. Vcs Quasistatic & high frequency capacitance vs.

1 Description

High-frequency capacitance vs. gate voltage

Units

pF vs. V
pF vs. V
pF vs. V

gate voltage - - 1 _
Current vs. gate voltage
High fxquency conductance vs. gate voltage

Dopinz profile vs. depth

N vs. w N vs. w
l/C?? vs. vcs l/C?? vs. vcs

ZiigleF(MCC) dopink profile vs. depth ZiigleF(MCC) dopink profile vs. depth

l/C? vs. gate voltage l/C? vs. gate voltage

w vs. vcs w vs. vcs Depth vs. gate voltage Depth vs. gate voltage
Dm vs. K Dm vs. K Interface trap density vs. trap energy Interface trap density vs. trap energy
us vs. VG5 us vs. VG5

Band bending vs. gate voltage Band bending vs. gate voltage
Quasistatic &pa&&e vs. bvand bending
High-frequency capacitance vs. band bending

*R vs. Vcr for series model.

NOTE: Where indicated, plots can be normalized to Cm by selecting appropriate aption an menu

pA vs. V
j.l.5 vs. v
an” vs. pm or run
cd vs. pm or mm
pF-2 vs. v
pl vs. v
alT2ev- vs. ev
vvs.v
pF vs. V

pF vs. V

Co/Cox optional
CH/COX optional
CdCox, CdCox optional

(COX/CF# optional

cQ/cOX OptiOnal

CH/COX optional

4-17

SECTION 4

4.6.2

Graphing Data

Selecting a graphing option will cause a graph to be gen-

eratedonthescreen,alongwiththegraphicscontrolwin-

dow.

NOTE
A particular graph retains its configuration
until a new reading array is analyzed.

The graphics control menu is shown in Figure 4-11.
Through this menu you can select the following:

1.

Auto Scaling. When auto scaling is selected, the
minimum and maximum values for the data will
automatically be used as the limits for both X and Y
axes.

2.

Axes Limits. This option allows you to select the
minimum and maximum limits for both X and Y
axes,anditcanbeused tozoominonaportionofthe

curve. At the prompts, type in Xmin, Xmax, Ymin,

and Ymax (minim

urn must be less than maximum).

To leave a parameter unchanged, simply press En­ter. See also paragraph 4.4.4 for information onusing
the graphics range as an alternative.

3.

Plot Graph. This option dumps the complete graph
including the curve and axes to the printer or plotter
(depending on the selected hard copy device). Note,

however, that the graphics control menu will not ap-

pear on the hard copy plot. Plot resolution and size
can be controlled, as discussed below.
Plot curve. Use this option to generate the curve

4,

only with the external plotter. This feature is useful

for drawing more than one curve on a graph.

5

ChangeNotes.Youcantypeintwolinesofnotesthat
will appear at the top of the graph by using this op­tion. The notes will also appear on any hard copy
plot made of the graph. Each line is entered sepa­rately.

6,

A.

Normalize to Cm. This option is available only

when plotting CQ or CH vs. some other parameter
such as gate voltage of band bending. When se­lected, the Y axis will show C/Cox.

B.

Lin/Log Graph. This option is available only for
plots other than CQ or CH. When log is selected,
the Y axis is plotted logarithmically, but the X
axis remains linear. Note that absolute values are

plotted using the log option.

7.

Adjust Gain/Offset CQ or CH. Enter a new value at
each prompt (see discussion below on using cursor
marking).

8.

Exit.

QURSISTRTIC CRPRCITRNCE VS. GATE ‘VCILTRGE EXRMPLE

iNORMHLIZED Ti? Cox I

7 i..............i..~............:...............;....;..................~~...~.~~~....~.....~...~~~...~..~..~...........~...~~..~~......~...~.~~...~.......~~

._

-5.m

mu: 1) Ruto Scale

Enter number !.? select from menu

-3.00

GATE '!rjLTHOE ( ‘,.J )

2) Rles Limits

-1.00 I .QEI

.$I Plot G-aoh 411 Pint Curve

3.m s.om

SECTION 4

Printer Size and Resolution

From the graphics menu, you can control the size and
resolution of your hard copy graphs made on printer by
pressing one of the following letters:

m Half page, low-resolution plot

Half page, high-resolution plot

M

1 Full page, low-resolution plot

L Full page, high-resolution plot

Abort plot and rehnn to graphics menu

Q

Note that selecting option 3 or 4 on the graphics menu
automatically generates a half-page, low-resolution
curve or graph on the printer.

Plotter Size

With a plotter, you can control the plot size. This selection

will be displayed on the screen after you select the plot-

ting option on the graphics menu.

You can also use the Insert key to draw a line on the
graph. Move the cursor the first location, then press the
ENTER key to mark the point. Move the cursor to the sec­ond location, the press the Insert key to draw the line.

Overlaying Curves

When using a plotter, you can overlay a number of curves

on the same graph. To use this feature, first plot the entire
graph by selecting option 3 (plot graph) on the graphics
control menu. Load you next data set, then generate the
curve by selecting option 4 (plot curve). Repeat this proc­ess for as many curves as you wish to overlay.

Needless tosay, theXandY axisscalingfactorsforallsets

of overlay data must be the same, or the resulting curve
overlays will have minimal analytical value.

Threshold Voltage and Flatband Voltage Display

Threshold voltage and flatband voltage are automati­callymarkedasVthandVfbonanygra.phwhichdisplays
vcs along the x axis. You can toggle this display on or off
by pressing the “V” key.

Cursor operation

To make it easier to change axes scales and gainand offset
values, a cursor marker facility is included with Model

82.DOS. To use this feature, type “C” or “c” from the
graphics menu. Once enabled, a cursor will be displayed
on the screen, and you can move that cursor around the
screen using the arrow keys. The value corresponding to
the present cursor location will be displayed at the bot­tom of the screen.

To mark a specific location, press the ENTER key. The lo­cation will be marked with a set of crosshairs on the
graph. Move the cursor to the second location with the
cursor keys, and note that dy (change in y) and ry (ratio
between present y location and marked y location) are
displayed on the bottom of the screen. To mark the sec­ond location, press ENTER a second time, then press the
ESC key to exit the cursor mode. Subsequently selecting
the Axes Limits or Gain/Offset options will cause both
markers to be displayed on the screen along with the dif­ferences between them. You can then use this informa­tion to set your new axes limits, or gain and offset values.

4.6.3

During a voltage sweep, Ca, CH, G, Q/t, and Vcs are
stored in the reading array where:

CQ = Quasistatic capacitance

CH = High-frequency capacitance
G = Conductance
Q/t = Current
Vcs = Gate voltage. Note that the substrate voltage is

measured by the Model 590 and is changed to VCS by ne­gation.

Array readings are made at every other voltage step, but
if the filter is on, the first four CQ’ and Q/t readings are
invalid, so they are discarded.

Q/t, G, CH, and VH and all measured at the same point in
the sweep, but CQ’ is measured one-half step V before VH
is measured. Since some calculations require that Ca and

Reading Array

4-19

SECTION 4
Analysis

CH are measured at the same voltage, CQ’ must be inter­polated to Co as follows:

c,(i) =CQ,(i)+C~‘(i+l)-C~‘(i)v-

V&+1) - V&) 2

=CQ’(i)+--SE

After interpolation, the Co and CH values are adjusted ac­cording to programmed gain and offset values to deter­mine CQA and CHA (adjusted CQ and CH). CQA and CQH are
the values actually plotted, printed, and used in calcula­tions.

4.6.4 Graphics Array

In order to support the analysis functions, array includes
w, N, ~JS, ET, and Drr where:

w = Depletion depth or thickness
N = Doping concentration

I+& = Band bending
ET = Interface trap energy

Drr= Density of interface traps

l/C’ = High-frequency capacitance

Ziegler w = Ziegler (MCC) depletion depth

Ziegler N = Ziegler (MCC) doping concentration

Graphics Array Shuctie

The graphics array is constructed by solving for these pa­rameters at each value of VGS using CQA, CHA, Cox, and

gate area. The graphics array is recalculated each time
analysis is selected on the menu, if new data has been
taken, or if a reading data file is loaded from disk. If 6x,
LOX, and gate area are not defined, the array is not calcu-

la&d, and the user is notified.

AG v

AVH 2

Changing Device Constants

Changing Cox, gate area, or tax will cause the entire
graphics array to be recalculated. Changing Nsurx will
cause Cm, ~5, and ET to be recalculated.

Invalid Array Values

Most of the equations used for analysis can have a situ-

ation where a divide by zero error could occur in certain
circumstances (for example, if CH = COX, or CH (i) = CH
(i+l)). In order to avoid problems, avery highvalue (109

is placed in any array element where such a divide by

zero error occurred. During plotting, a test for 1O32 is
done, and the pen is lifted for invalid values. As a result,

the curve will be generated only over areas of valid data.

Discontinuous areas are normal with some curves be­cause trap tests are intended only for depletion; also
curves might not be properly aligned, resulting in invalid
areas when plotting Dn.

4.6.5

Data from the reading array can be graphed by selecting

the appropriate option(s) on the analysis menu. Data that

can be plotted includes:

CQA vs. VGS

CHA vs. vcs
Both CQA and CHA vs. VGS on the same graph
Q/t vs. VGS
G vs. Vcs (R vs. VCS for series device model)

Note that compensated Co and CH are the values plotted.

Examples of these graphs are shown in Figure 4-12
through Figure 4-16.

Graphing the Reading Array

4-20