Tektronix 4200A-SCS User manual
Model 4200A-SCS
Capacitance-Voltage Unit (CVU)
User's Manual
tek.com/keithley
4200A-CVU-900-01 Rev. B
March 2023
*P4200A-CVU-900-01B*
4200A-CVU-900-01B
Capacitance-Volt age Unit (CVU)
Model 4200A-SCS
User's Manual
© 2023, Keithley Instruments
Cleveland, Ohio, U.S.A.
All rights reserved.
Any unauthorized reproduction, photocopy, or use of the information herein, in whole or in part,
without the prior written approval of Keithley Instruments is strictly prohibited.
All Keithley Instruments product names are trademarks or registered trademarks of Keithley
Instruments, LLC. Other brand names are trademarks or registered trademarks of their
respective holders.
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Document number: 4200A-CVU-900-01 Rev. B March 2023
Safety precaut ions
The following safety precautio ns should be observed before using this product and any associated ins t rum enta tion. Although
some instruments and accessories would normally be used with nonhazardous voltages, there are situations where hazardous
conditions may be present.
This product is intended for use by 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 user documentation for complete product specifications.
If the product is used in a manner not specified, the protection provided by the product warranty 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 user documentation. 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, perform safe installations, and repair products. Only properly trained
service personnel may perform installation and service procedures.
Keithley products are designed for use with electrical signals that are measurement, control, and data I/O connections, with low
transient overvoltages, and must not be directly connected to mains voltage or to voltage sources with high transient
overvoltages. Measurement Category II (as referenced in IEC 60664) connections require protection for high transient
overvoltages often associate d with local AC mains connections. Certain Keithley measuring instruments may be connected to
mains. These instruments will be marked as category II or higher.
Unless explicitly allowed in the specif icat ion s, opera ting manual, and instrument labels, do not connect any instru ment to mains.
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
30 V RMS, 42.4 V peak, or 60 VDC 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 V, 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, ensure that 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.
For safety, instruments and accessories must be used in accordance with the operating instructions. If the instruments or
accessories are used in a manner not specified in the operating instructions, the protection provided by the equipment ma y be
impaired.
Do not exceed the maximum signal levels of the instruments and accessories. Maximum signal levels are defined in the
specifications and operating information and shown on the instrument panels, test fixture panels, and switching cards.
When fuses are used in a product, replace with the same type and rating for continued protection against fire hazard.
Chassis connections must only be used as shield connections for measuring circuits, NOT as protective earth (safety 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.
If a
The
screw is present, connect it to protective earth (safety ground) using the wire recommended in the user documentatio n.
symbol on an instrument means caution, risk of hazard. The user must refer to the operating instructions located in the
user documentation in all cases where the symbol is mark ed on the instr u ment .
The
symbol on an instrument means warning, risk of electric shock. Use standard safety precautions to avoid personal
contact with these voltages.
The symbol on an instrument shows that the surface may be hot. Avoid personal contact to prevent burns.
The
If this
symbol indi cates a connection terminal to the equipment frame.
symbol is on a product, it indicates that mercury is present in the display lamp. Please note that the lamp must be
properly disposed of according to federal, state, and local laws.
The WARNING heading in the user documentation explains hazards that might result in personal injury or death. Always read
the associated information very carefully before performing the indicated procedure.
The CAUTION heading in the user documentation explains h azard s that coul d dama ge the instrument. Such damage may
invalidate the warranty.
The CAUTION heading with the
symbol in the user documentation explains hazards that could result in moderate or minor
injury or damage the instrument. Always read the as soc iate d infor mation very carefully before performing the indicated
procedure. Damage to the instrument 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. Standard fuses with applicable national safety
approvals may be used if the rating and type are the same. The detachable mains power cord provided with the instrument may
only be replaced with a similarly rated power cord. Other components that are not safety-related may be purcha sed fr om ot her
suppliers as long as they are equivalent to the original component (note that selected parts should be purchased only through
Keithley to maintain accuracy and functionality of the product). If you are unsure about the applicability of a replacement
component, call a Keithley office for information.
Unless otherwise noted in product-specific literature, Keithley instruments are designed to operate indoors only, in the following
environment: Altitude at or below 2,000 m (6,562 ft); temperature 0 °C to 50 °C (32 °F to 122 °F); and pollution degree 1 or 2.
To clean an instrument, use a cloth dampened with deionized water 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., a 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.
Safety precaution revision as of June 2018.
Table of contents
Introduction .............................................................................................................. 1-1
Introduction .......................................................................................................................... 1-1
Capacitance-Voltage Unit (CVU) ......................................................................................... 1-1
Test signal ............................................................................................................................ 1-2
Connections ............................................................................................................. 2-1
CVU connections ................................................................................................................. 2-1
Connection notes ...................................................................................................................... 2-1
Prober accessories for the CVU ................................................................................................ 2-2
Typical CVU test connections to a DUT .................................................................................... 2-3
Simplified model of a DUT......................................................................................................... 2-4
Typical test connections to a probe card ................................................................................... 2-5
Typical CVU matrix card connections ....................................................................................... 2-5
Connection compensation ................................................................................................... 2-8
Generate open connection compensat ion dat a ......................................................................... 2-8
Generate short connection compen sat ion data ....................................................................... 2-11
Generate load connection compensatio n dat a ........................................................................ 2-13
Compensation data ................................................................................................................. 2-15
Enable compensation .............................................................................................................. 2-15
ABB unbalance errors ............................................................................................................. 2-17
CVU Confidence Check ..................................................................................................... 2-17
Run an open check and short check ....................................................................................... 2-18
CVU Real-Time Measurement ........................................................................................... 2-19
Setting up CVUs in Clarius ...................................................................................... 3-1
CVU project example ........................................................................................................... 3-1
Select a project ......................................................................................................................... 3-1
Configure the test ...................................................................................................................... 3-3
Run the test and review results ................................................................................................. 3-3
Selecting the DC Operation Mode ....................................................................................... 3-5
Voltage Bias .............................................................................................................................. 3-5
Voltage Linear Sweep ............................................................................................................... 3-5
Voltage List Sweep ................................................................................................................... 3-5
Voltage Step.............................................................................................................................. 3-6
DC Gnd operation mode - CVU ................................................................................................. 3-6
Selecting the Freq Operation Mode ..................................................................................... 3-6
Frequency Single Freq .............................................................................................................. 3-6
Frequency Linear Sweep .......................................................................................................... 3-6
Freq Log Sweep ........................................................................................................................ 3-7
Freq List Sweep ........................................................................................................................ 3-7
Freq Step .................................................................................................................................. 3-7
Making additional test settings ............................................................................................. 3-8
Typical test setups with timing diagrams ............................................................................. 3-9
DC bias function and sweep characteristics .............................................................................. 3-9
CVU using voltage bias ........................................................................................................... 3-11
CVU using voltage sweep ....................................................................................................... 3-12
CVU using voltage li st sweep .................................................................................................. 3-13
Table of contents
User's Manual
Model 4200A-SCS Capacitance-Voltage Unit (CVU)
CVU using a dc voltage bias and a frequency sweep ............................................................. 3-15
CVU frequency sweep - DC step ............................................................................................ 3-17
CVU voltage linear sweep - f requency step ............................................................................ 3-19
Force-measure timing ........................................................................................................ 3-22
Bias function timing ................................................................................................................. 3-22
Sweep function timing ............................................................................................................. 3-23
CVU - all terminal parameters ............................................................................................ 3-23
Presoak ................................................................................................................................... 3-23
Start ........................................................................................................................................ 3-23
Stop ......................................................................................................................................... 3-23
Step (voltage sweep) .............................................................................................................. 3-23
List Values............................................................................................................................... 3-24
Freq Operation Mode .............................................................................................................. 3-24
Start (Freq Operation Mode) ................................................................................................... 3-24
Stop (Freq Operation Mode) ................................................................................................... 3-24
Step (Freq Operation Mode) ................................................................................................... 3-24
Frequency Points (Freq Operation Mod e) ............................................................................... 3-25
AC Drive Signal ....................................................................................................................... 3-25
Points ...................................................................................................................................... 3-25
Points (list or segment sweep) ................................................................................................ 3-25
Dual Sweep ............................................................................................................................. 3-25
DC Bias ................................................................................................................................... 3-26
Frequency ............................................................................................................................... 3-26
Parameters.............................................................................................................................. 3-26
Param1 Column Name ............................................................................................................ 3-27
Param2 Column Name ............................................................................................................ 3-28
Report Test Conditions ........................................................................................................... 3-28
DCV Column Name ................................................................................................................. 3-28
Freq Column Name ................................................................................................................. 3-28
Report Status (CVU) ............................................................................................................... 3-29
Open ....................................................................................................................................... 3-29
Short ....................................................................................................................................... 3-29
Load ........................................................................................................................................ 3-29
Cable Length ........................................................................................................................... 3-29
CVU Terminal Settings Advanced settings and circuits ..................................................... 3-30
AC Source V ........................................................................................................................... 3-31
AC Measure I Range ............................................................................................................... 3-31
DC Source V ........................................................................................................................... 3-32
DC Offset ................................................................................................................................ 3-32
Capacitance Range Estimator ................................................................................................. 3-32
CVU test settings ............................................................................................................... 3-32
CVU speed settings ................................................................................................................ 3-33
Report Timestamps ................................................................................................................. 3-37
Test Mode ............................................................................................................................... 3-38
Sweep Delay ........................................................................................................................... 3-39
Interval .................................................................................................................................... 3-39
Number of Samples ................................................................................................................ 3-39
Hold Time ................................................................................................................................ 3-39
Disable outputs at completion - CVU ...................................................................................... 3-40
Output Values ......................................................................................................................... 3-40
C-V projects .............................................................................................................. 4-1
C-V projects ......................................................................................................................... 4-1
BJT Capacitance Tests (cvu-bjt) .......................................................................................... 4-3
cvu-bjt connections ................................................................................................................... 4-3
Formulas and constants ............................................................................................................ 4-5
Model 4200A
contents
-SCS Capacitance-Voltage Unit (CVU) User's Manual Table of
c-cb0 test................................................................................................................................... 4-5
c-ce0 test................................................................................................................................... 4-5
c-be0 test .................................................................................................................................. 4-6
BJT I-V and C-V Tests Using 4200A-CVIV Multi-Switch Project (cvu-bjt-cviv) ................... 4-7
Capacitor I-V and C-V Measurements with Series 700 Project (cap-iv-cv-matrix) .............. 4-8
cap-iv-cv-matrix project summary ............................................................................................. 4-9
cap-iv-cv-matrix connections ................................................................................................... 4-10
Formulas and constants .......................................................................................................... 4-11
connect test ............................................................................................................................. 4-11
iv-cap test ................................................................................................................................ 4-11
connect-cv test ........................................................................................................................ 4-12
cv-capacitor test ...................................................................................................................... 4-12
Capacitor Measurements (cap-measurements) ................................................................ 4-13
cvu-capacitor connection s ....................................................................................................... 4-13
Formulas and constants .......................................................................................................... 4-13
cv-10 pF test ........................................................................................................................... 4-13
cf-10 pF test ............................................................................................................................ 4-14
Carbon Nanotube Transistor Characterization Project (cntfet -characterization) ............... 4-14
Demo project (default) ........................................................................................................ 4-15
cv-nmosfet test ........................................................................................................................ 4-15
cv-diode test ............................................................................................................................ 4-15
cv-cap test ............................................................................................................................... 4-15
Diode Project (diode) ......................................................................................................... 4-16
diode connections ................................................................................................................... 4-17
diode project formulas and constants ...................................................................................... 4-18
diode-cvsweep test ................................................................................................................. 4-19
diode-c-2vsv test ..................................................................................................................... 4-20
diode-dopingprofile test ........................................................................................................... 4-21
High-Voltage C-V Tests Project (cvu-highv) ...................................................................... 4-21
High Voltage C-V Tests Using 4200A-CVIV Bias Tee Project (cviv-bias-highv) ............... 4-22
MOS Capacitor C-V Project (cvu-moscap) ........................................................................ 4-23
MOS capacitor C-V curves ...................................................................................................... 4-24
Accumulation region ................................................................................................................ 4-24
Depletion region ...................................................................................................................... 4-25
Inversion region ....................................................................................................................... 4-25
cvu-moscap connections ......................................................................................................... 4-26
cvu-moscap project formulas .................................................................................................. 4-27
cvu-moscap project constants ................................................................................................. 4-34
moscap-cvsweep test .............................................................................................................. 4-35
moscap-c-2vsv test ................................................................................................................. 4-35
moscap-dopingprofile test ....................................................................................................... 4-37
Compensating for series resistance ........................................................................................ 4-38
Extracting MOS device parameters from C-V measurements ................................................. 4-40
MOS Capacitor Lifetime Test Project (moscap-lifetime) .................................................... 4-46
moscap-lifetime connections ................................................................................................... 4-46
moscap-lifetime formulas and constants ................................................................................. 4-47
c-v test .................................................................................................................................... 4-50
c-t test ..................................................................................................................................... 4-51
gni-w-wf test ............................................................................................................................ 4-51
MOS Capacitor Mobile Ion Project (moscap-mobile-ion) ................................................... 4-54
moscap-mobile-ion connections .............................................................................................. 4-57
Formulas and constants .......................................................................................................... 4-57
Run the project ........................................................................................................................ 4-58
cv-vfb1 test .............................................................................................................................. 4-58
Table of contents
User's Manual
Model 4200A-SCS Capacitance-Voltage Unit (CVU)
bias-pos test ............................................................................................................................ 4-59
hotchuck action ....................................................................................................................... 4-60
cv-vfb2 test .............................................................................................................................. 4-60
bias-neg test ............................................................................................................................ 4-60
hotchuck action ....................................................................................................................... 4-61
cv-vfb3 test .............................................................................................................................. 4-61
MOSFET 3-Terminal C-V Tests Using the 4200A-CVIV Bias Tees (mosfet-cviv-cv-bias-tees and
mosfet-cviv-cv-bias-tees-400V) ......................................................................................... 4-62
MOSFET I-V and C-V Tests Using 4200A-C VIV Multi-Switch Project (mosfet-cviv)......... 4-62
MOSFET Project (mosfet) .................................................................................................. 4-63
mosfet connections ................................................................................................................. 4-64
mosfet formulas and constants ............................................................................................... 4-65
g-to-sdb and mosfet-dopingprofile Analyze sheet ................................................................... 4-70
Solar Cell Project (solarcell) ............................................................................................... 4-70
solarcell connections ............................................................................................................... 4-71
solarcell formulas and constants ............................................................................................. 4-72
fwd-ivsweep test ...................................................................................................................... 4-76
rev-ivsweep test ...................................................................................................................... 4-76
solarcell-cvsweep test ............................................................................................................. 4-77
solarcell-c-2vsv test ................................................................................................................. 4-77
cfsweep test ............................................................................................................................ 4-78
Interconnect Capacitance C-V Sweep test (cv-sweep) ..................................................... 4-79
cv-sweep connections ............................................................................................................. 4-79
Formulas and constants .......................................................................................................... 4-79
Analyze sheet .......................................................................................................................... 4-80
Nanowire tests ................................................................................................................... 4-80
cvu-nanowire connection s ....................................................................................................... 4-80
Formulas and constants .......................................................................................................... 4-81
cv-gd and cv-sd tests .............................................................................................................. 4-82
Make C-V measurements on a MOSCAP ................................................................ 5-1
Introduction .......................................................................................................................... 5-1
Equipment required .............................................................................................................. 5-1
Device connections .............................................................................................................. 5-2
Connect the 4200A-SCS to the DUT ......................................................................................... 5-2
Set up the measurements in Clarius .................................................................................... 5-4
Search for and select a project .................................................................................................. 5-4
Configure the test ...................................................................................................................... 5-5
Perform offset compensation .................................................................................................... 5-8
Run the test ............................................................................................................................. 5-11
View and analyze the test results ............................................................................................ 5-11
Test signal ................................................................................ 1-2
In this section:
Introduction .............................................................................. 1-1
Capacitance-Voltage Unit (CVU) .............................................. 1-1
Introduction
This document provides information about the 4210-CVU and 4215-CVU capacitance-v olta ge unit s,
including:
• Connections (on page 2-1): Basic information on connecting CVUs to DUTs, making test
equipment connections, making control and data connections, and configuring the system
in KCon.
Section 1
Introduction
• Setting up CVUs in Clarius (on page 3-1): Provides a brief example of setting up CVUs in Clarius
and descriptions of the terminal and test settings.
• C-V projects (on page 4-1): Provides descriptions of the C-V projects in Clarius.
• Make C-V measurements on a MOSCAP (on page 5-1): Presents a step-by-step
application example.
Capacitance-Vo l tage Unit (CVU)
The 4210-CVU and 4215-CVU Multi-Frequency Capacitance-Voltage Units are impedance
measurement modules that can be installed in the 4200A-SCS.
Capacitance-voltage (C-V) measurements are often used to characterize the gate oxide thickness,
oxide defect density, and doping profile of MOSFETs. In these measurements, as the gate voltage
varies, the capacitance of the gate to the drain and source changes. Capacitance measurements are
typically made using an ac technique. The CVUs measure ac impedance by applying a dc bias
voltage and sourcing an ac voltage across the device under test (DUT) and then measuring the
resultant ac current and phase angle.
The 4210-CVU operates from 1 kHz to 10 MHz. The ac test signal (10 mV
dc voltage biased from −30 V to +30 V.
to 100 mV
RMS
) can be
RMS
The 4215-CVU operates from 1 kHz to 10 MHz at 1 kHz resolution. The ac test signal (10 mV to
1 V
) can be dc voltage biased from −30 V to +30 V.
RMS
Section
User's Manual
1: Introduction Model 4200A-SCS Capacitance-Voltage Unit (CVU)
Test signal
The test signal can be set for the following frequencies.
For the 4210-CVU:
• 1 kHz to 10 kHz in 1 kHz increments
• 10 kHz to 100 kHz in 10 kHz increments
• 100 kHz to 1 MHz in 100 kHz increments
• 1 MHz to 10 MHz in 1 MHz increments
The ac signal output level can be set from 10 mV
to 100 mV
RMS
impedance is 100 Ω (typical). The ac voltage measure range is 100 mV
RMS
(1 mV
RMS
resolution). The output
RMS
.
The ranges available to measure current are 1 μA, 30 μA, or 1 mA. With autorange selected, range
selection is done automatically.
For the 4215-CVU:
• 1 kHz to 10 MHz in 1 kHz increments
The ac signal output level can be set from 10 mV
RMS
to 1 V
impedance is 100 Ω (typical). The ac voltage measure range is 1 mV
The ranges available to measure current are 1 μA, 30 μA, or 1 mA. With autorange selected, range
selection is done automatically.
RMS
(1 mV
resolution). The output
RMS
.
RMS
1-2 4200A-CVU-900-01 Rev. B March 2023
CVU Real-Time Measurement ............................................... 2-19
In this section:
CVU connections ..................................................................... 2-1
Connection compensation ........................................................ 2-8
CVU Confidence Check ......................................................... 2-17
CVU connections
The CVU is shipped with four red 1.5 m SMA cables (plug-to-plug, 100 Ω). These characterized
cables must be used for connection to the CVU to achieve optimum performance.
Section 2
Connections
If you have the 4200-CVU-PROBER-KIT, you also have four red 3 m SMA cables
(plug-to-plug, 100 Ω).
If you have the 4225-RPM Remote Amplifier/Switch Module (available as an accessory for the
4225-PMU UltraFast Pulse Measure Unit), you can use the RPM for switching between SMUs, CVUs,
and PMUs. For switching connection information, refer to “Use the RPM to switch the SMU, CVU, and
PMU” in Model 4200A-SCS Pulse Card (PGU and PMU) User’s Manual (4200A-PMU-900-01).
Connection notes
• Use only the supplied red SMA cables for connections to the 4210-CVU or 4215-CVU.
• Do not use a mix of cable lengths on different CVU terminals.
• Use the supplied torque wrench to tighten SMA cable connectors to 8 in. lb.
• In Clarius, the cable length setting of a test must match the length of the SMA cables used for
your setup.
• If you need to run connection compensation, do it after setting up connections or after making
changes to existing connections, but before running any tests. See the Connection compensation
(on page 2-8) topic.
• When making connections from the CVU to the device under test (DUT), make sure the shields of
the SMA cables are connected as close as possible to the DUT.
• Use coaxial cables to extend SMA shielding to the DUT, then connect them.
Section
User's Manual
Keithley part number or
A 4 CA-446
Red SMA cables, male to male, 100 Ω, 3 m
B 4 CS-565
BNC female to BNC female adapter
C 4 7078-TRX-GND
Triaxial male to BNC female adapter (with guard remov ed)
D 4 7078-TRX-BNC
Triaxial male to BNC female adapter (with guard conne cted
to the inner shield of the adapter)
E 4 237-TRX-BAR
Triaxial female to triaxial female adapter
F 4 CS-1247
SMA female to BNC male adapter
G 2 CS-1391
SMA Tee adapter (female, male, female)
H 2 4200-PRB-C
SMA to SSMC dual (with local ground)
2: Connections Model 4200A-SCS Capacitance-Voltage Unit (CVU)
Prober accessories for the CVU
The Model 4200-CVU-PROBER-KIT is an accessory kit that provides connections to a wide variety of
prober and manipulator types. This kit contains a combination of triaxial and BNC adapters and
barrels that accommodate most prober connection requirements.
The following figure shows the accessories that are included in the kit.
Figure 1: Model 4200-CVU-PROBER-KIT
The following table lists the cables and adapters provided with the prober kit.
Supplied cables and adapters for the Model 4200-CVU-PROBER-KIT
Item Quantity
model number Description
When using the Model 4200-PRB-C cables (item H), be sure you jumper the shields together at the
probe tips. Each stackable black banana plug is connected to the outer shield of the cables.
2-2 4200A-CVU-900-01 Rev. B March 2023
Mo
del 4200A-SCS Capacitance-Voltage Unit (CVU) User's Manual Section 2:
Connections
Typical CVU test connections to a DUT
The shields of the SMA cables must be connected together and extended as far as possible to the
device under test (DUT), as shown in the following figure.
Use the supplied torque wrench to tighten the SMA connections to 8 in. lb.
Figure 2: Measurement circuit (simplified)
You can swap the HCUR and HPOT and LCUR and LPOT terminal functionality in Clarius.
The shields of the red SMA cables must be connected together near the DUT.
The following figure shows typical connections to a DUT installed in a test fixture that has BNC
bulkhead connectors. Use a conductive test fixture with the bulkhead connectors mounted directly to
the test fixture. Do not use insulators between the connectors and test fixture. The cables and
adapters shown are the ones supplied with the 4210-CVU or 4215-CVU.
4200A-CVU-900-01 Rev. B March 2023 2-3
Section
User's Manual
2: Connections Model 4200A-SCS Capacitance-Voltage Unit (CVU)
Figure 3: Typical CVU connections to a DUT in a test fixture
Simplified model of a DUT
The CVU makes ac impedance measurements (Z
) of the device under test (DUT) by sourcing an
DUT
ac test voltage across the device and measuring the resulting ac current and ac voltage.
The ac current is measured as shown in Typical CVU test connections to a DUT (on page 2-3
).
The HCUR/HPOT and LCUR/LPOT terminal pairs are interchangeable. Each provides the full
capability of the other pair.
The simplified model of a DUT is a resistor and a capacitor. As shown in the following figure, the CVU
can measure the DUT as a series configuration of the resistor-capacitor (RC) or as a parallel
RC configuration.
Figure 4: Measure models (simplified)
2-4 4200A-CVU-900-01 Rev. B March 2023
Model 4200A
Connections
-SCS Capacitance-Voltage Unit (CVU) User's Manual Section 2:
Typical test connections to a probe card
The 4200-CVU-PROBER-KIT includes 3 meter SMA cables and connection accessories to connect
the 4210-CVU or 4215-CVU to a probe card. Refer to Prober accessories for the CVU (on page 2-2
for a list of the supplied items.
The following figure shows typical test connections to a probe card. The connections use triaxial
socket connectors. The probe kit includes two types of BNC to triaxial adapters. The 7078-TRX-BNC
has the guard connected to the inner shield of the adapter. The 7078-TRX-GND has the guard
disconnected. In most applic ations , the 707 8-TRX-BNC is the preferred adapter.
Figure 5: Typical connections to a probe card
)
The shields of the SMA cables must be connected together and extended as far as possible to the
DUT, as shown in Typical CVU test connections to a DUT (on page 2-3
If the probe card uses BNC (socket) connectors, you do not need the BNC-to-triaxial adapters.
Typical CVU matrix card connections
In your project, you can automate the use of a CVU and other instrumentation using a switching
matrix and actions to control the switching. When the project is run, the switching matrix automatically
makes the required instrument connections for each test in the project.
The next figures show typical connecti ons for a switch s y stem using a Series 700 Switch in g Syste m
with the 7174A Matrix Card installed.
).
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You can also use the 7072 Matrix Card for C-V testing. If you are using the 7072, you must use rows
G and H and local (2-w ir e) s ens ing.
The SMA cables and adapters shown in the following figures are supplied with the CVU or the
4200-CVU-PROBER-KIT. The triaxial and BNC cables are not supplied. The prober kit includes two
types of BNC-to-triaxial adapters that connect directly to the rows of the matrix. The 7078-TRX-BNC
has the guard connected to the inner shield of the adapter. The 7078-TRX-GND has the guard
disconnected.
This figure shows connections for local (2-wire) sensing with the CVU connected to rows E and F of
the matrix. This is the connection scheme for the cap-iv-cv-matrix project. For details, see
cap-iv-cv-matrix (on page 4-8
).
Figure 6: Test connections for a switching matrix - local (2-wire) sensing
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The following figure shows connections for remote (4-wire) sensing.
Figure 7: Test connections for a switching matrix - remote (4-wire) sensing
The 7078-TRX-BNC adapters must be used in order to extend SMA shielding through the
matrix card.
The shields of the SMA cables must be connected together and extended as far as possible to the
DUT, as shown in Typical CVU test connections to a DUT (on page 2-3
).
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Connection compensation
You can correct offset and gain errors caused by the connections between the CVU and the device
under test (DUT) by using connection compensation. To use correction, you:
• Generate connection compensation data for open, short, and load conditions.
• Enable CVU connection compensation.
When a test is run, the enabled compensation values are factored in by each measurement.
If open, short, or load compensation is disabled, those compensation values are not used by the test.
Once compensation values are stored, they are available to any project that uses a CVU.
Update connection compensation any time the connection setup is changed or disturbed. Changes
in temperature or humidity do not affect connection compensation.
If the CVU is connected to a 4200A-CVIV Multi-Switch, run the cvu-cviv-comp-collect action.
Refer to the Model 4200A-CVIV Multi-Switch User’s Manual for detail.
Use the following general guidelines to determine which correction needs to be done:
• Open correction: Offset correction for small capacitances (>1 MΩ, large impedance).
• Short correction: Offset correction for large capacitances (<10 Ω, small impedance).
• Load correction: Resistive load correction for gain error. Keithley recommends a load that is as
close in impedance to the cabling system (100 Ω) as possible. The load must have an impedance
versus frequency characteristic that is purely resistive over the frequency range of
subsequent measurements.
Generate open connection compensation data
Open connection compensation is usually done to offset correction for small capacitances.
Open compensation is done with all the cables, adapters, switch matrices, and other hardware
connections connected to the device under test in the test circuit. The probes must be lifted up or the
device must be removed from the test fixture.
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To generate open connection compensation da ta:
1. Make the connections to the CVU, as shown in the following figure. For remote (4-wire) sensing,
the shields of the four SMA cables must be connected as close as possible.
Figure 8: Connections for open connection compensation CVU
2. In Clarius, select Tools. The Clarius Tools dialog opens.
Figure 9: Clarius Tools dialog
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3. Select CVU Connection Compensation.
Figure 10: CVU Connection Compensation dialog
4. Select the cable length. You can select:
0 m: Use if measurements are made at the terminals of the CVU (no cables).
1.5 m: Use with the standard red SMA cables (part number CA-447A) that are supplied with
the CVU.
3 m: Use with the red SMA cables (part number CA-446) that are supplied with the
4200-CVU-PROBER-KIT. You can also use this setting if you are using a switching matrix.
Custom: Cable length coefficients are measured by the user using the Measure Custom
Cable Length option under Advanced Compensation.
5. If you selected Custom cable length, select Advanced Compensation and select Measure
Custom Cable Length. Follow the on-screen instructions.
6. If you are using a switching matrix, close the matrix switches that connect the CVU to the open.
Refer to “Using Switch Matrices” in Model 4200A-SCS Prober and External Instrument Control.
7. In the Clarius CVU Connection Compensation dialog, select Measure Open.
8. Follow the instructions.
9. Select OK.
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Generate short connection compensation data
Short connection compensation is usually done to offset correction for large capacitances.
Short compensation is done by connecting all the CVU terminals directly together. A known short is
connected to the CVU terminals through all the cables, adapters, and probes that may be in the test
circuit. You can make a short at the wafer level by shorting all probes together.
To generate short connection compensatio n data:
1. Make the connections to the CVU, as shown in the following figure. For remote (4-wire) sensing,
the shields of the four SMA cables must be connected.
Figure 11: Connections for short and load connection compensation
2. In Clarius, select Tools. The Clarius Tools dialog opens.
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Figure 12: Clarius Tools dialog
3. Select CVU Connection Compensation.
Figure 13: CVU Connection Compensation dialog
4. Select the cable length. You can select:
0 m: Use if measurements are made at the terminals of the CVU (no cables).
1.5 m: Use with the standard red SMA cables (part number CA-447A) that are supplied with
the CVU.
3 m: Use with the red SMA cables (part number CA-446) that are supplied with the
4200-CVU-PROBER-KIT. You can also use this setting if you are using a switching matrix.
Custom: Cable length coefficients are measured by the user using the Measure Custom
Cable Length option under Advanced Compensation.
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5. If you selected Custom cable length, select Advanced Compensation and select Measure
Custom Cable Length. Follow the on-screen instructions.
6. If you are using a switching matrix, close the matrix switches that connect the CVU to the open.
Refer to “Using Switch Matrices” in Model 4200A-SCS Prober and External Instrument Control.
7. In the Clarius CVU Connection Compensation dialog, select Measure Short.
8. Follow the instructions.
9. Select OK.
Generate load connection compensation data
Loads are reference resistors, typically 50 or 100 Ω or less, that must be resistive and constant over
the entire frequency range (1 kHz to 10 MHz). A load is connected to the output terminals using all
the cables, adapters, probes, and other hardware in the test circuit.
To generate load correction data:
1. Make the connections to the CVU. See “Test connections for a switching matrix (on page 2-5
the Model 4200A-SCS Capacitance-Voltage Unit (CVU) User's Manual.
2. In Clarius, select Tools. The Clarius Tools dialog opens.
Figure 14: Clarius Tools dialog
)” in
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3. Select CVU Connection Compensation.
Figure 15: CVU Connection Compensation dialog
4. Select the cable length. You can select:
0 m: Use if measurements are made at the terminals of the CVU (no cables).
1.5 m: Use with the standard red SMA cables (part number CA-447A) that are supplied with
the CVU.
3 m: Use with the red SMA cables (part number CA-446) that are supplied with the
4200-CVU-PROBER-KIT. You can also use this setting if you are using a switching matrix.
Custom: Cable length coefficients are measured by the user using the Measure Custom
Cable Length option under Advanced Compensation.
5. If you selected Custom cable length, select Advanced Compensation and select Measure
Custom Cable Length. Follow the on-screen instructions.
6. If you are using a switching matrix, close the matrix switches that connect the CVU to the open.
Refer to “Using Switch Matrices” in Model 4200A-SCS Prober and External Instrument Control.
7. If it is not open, select Advanced Compensation.
8. In Measure Load, enter the value of the load in ohms.
9. Select Measure Load.
10. Follow the instructions.
11. Select OK.
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Compensation data
You can view the compensation data. Clarius lists R and jX compensation values for every test
frequency and measurement range for open, short, and load.
To view the data generated by connection compensation:
1. In Clarius, select Tools.
2. Select CVU Connection Compensation.
3. Select Advanced Compensation.
4. Next to View Compensation Data, select the data you would like to display: Open, Short, or
Load.
5. Select View Compensation Data.
6. Select the HI tab to review the high side values.
7. Select the LO tab to review the low side values.
Figure 16: Open compensation values example
Enable compensation
To use the values generated by connection compensation, you need to enable compensation for
each test.
When compensation is enabled, the most recently acquired CVU compensation data is applied.
Compensation values can be gathered using the CVU Connection Compensation option in Tools or
through actions and user modules.
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To enable compensation:
1. Select the test from the project tree.
2. Select Configure.
3. Select the terminal in the center pane.
4. In the right pane, select Terminal Settings.
5. Under Compensation, select the types of compensation as needed.
6. Make sure Cable Length is the same as the setting that was used in the Tools > CVU
Connection Compensation dialog to generate connection compensation data.
Figure 17: Enable connection compensation
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ABB unbalance errors
The CVU uses the autobalancing bridge (ABB) technique to achieve accurate impedance
measurements. ABB creates a virtual ground at the DUT to minimize measurement error. Every CVU
measurement is made with ABB active. The ABB always attempts to lock the low side of the DUT to
virtual ground.
If the ABB fails to lock, the measurement is made, but may be out of specification. If this occurs, the
returned data is flagged and shown in yellow on a blue background on the Analyze sheet.
The most common reasons that ABB fails to lock are:
• The cable lengths on the CVU terminals are not the same
• HPOT or LPOT terminals were disconnected
• Excessive noise on the LPOT terminal
• High frequency sources
• Physical cable lengths do not match the cable length set in Clarius
• Improperly torqued SMA cables
• Sub-optimal I
RANGE
setting
• Too much parasitic load on the low side of the DUT
You can use CVU Confidence Check to help troubleshoot ABB errors. Refer to
and short check (on page 2-18) for instructions on performing a confidence check.
CVU Confidence Check
CVU Confidence Check is a diagnostic tool that allows you to check the integrity of open and short
connections and connections to a device under test (DUT). When the CVU is connected to the DUT,
the Confidence Check displays the measured readings in real time in the Messages area of Clarius.
An open or short confidence check makes a measurement on the high and the low sides of the
test circuit.
The open check is not compatible with the 4200A-CVIV Bias Tee configurations.
To get the best results from a confidence check:
• Use the red CA-446A or CA-447A cables or equivalent.
Run an open check
• If applicable, make sure the prober chuck is connected.
• If you are using a switching matrix, make sure all channels are closed.
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Run an open check and short check
To run a CVU confidence check:
1. If you are using a switching matrix, connect the switching matrix to the CVU and DUT or the short
as explained in Test connections for a switching matrix (on page 2-5
2. For the short check, close the matrix switches to connect the CVU to the DUT or short. For the
open check, also close the matrix switches, but lift the probes or disconnect the DUT.
3. In Clarius, select Tools. The Clarius Tools dialog opens.
Figure 18: Clarius Tools dialog
).
4. Select CVU Confidence Check.
5. Select Check Open or Check Short.
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Figure 19: CVU Confidence Check dialog
6. Follow the instructions and select OK.
When the check is complete, the dialog displays the results of the test. If the test failed, the results
include suggestions for troubleshooting.
CVU Real-Time Measureme nt
The CVU Real-Time Measurement provides a direct real-time user interface to the CVU to help you
set up and debug your system. For example, you can use it to confirm that contact has been made
with the pads on a wafer. The measurements are independent of the open and short
confidence checks.
To make real-time measurements:
1. In Clarius, select Tools. The Clarius Tools dialog opens.
4200A-CVU-900-01 Rev. B March 2023 2-19
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