INFICON Q-pod User Manual

OPERATING MANUAL

Q-pod

Quartz Crystal Monitor

IPN 074-547-P1B

™

www.inficon.com [e-mail]

©2012 INFICON

®

OPERATING MANUAL

Q-pod

Quartz Crystal Monitor

IPN 074-547-P1B

™

Trademarks

The trademarks of the products mentioned in this manual are held by the companies that
produce them.

Q-pod™ is a trademark of INFICON GmbH.

Teflon® is a registered trademark of E. I. du Pont de Nemours and Company or its affiliates.

Windows®, is a registered trademark of Microsoft Corporation.

All other brand and product names are trademarks or registered trademarks of their respective companies.

Disclaimer

The information contained in this manual is believed to be accurate and reliable. However, INFICON assumes
no responsibility for its use and shall not be liable for any special, incidental, or consequential damages related
to the use of this product.

Due to our continuing program of product improvements, specifications are subject to change without notice.

Copyright

©2012 All rights reserved.
Reproduction or adaptation of any part of this document without permission is unlawful.

DECLARATION OF CONFORMITY

This is to certify that this equipment, designed and manufactured by:

INFICON Inc.

Two Technology Place

East Syracuse, NY 13057

USA

meets the essential safety requirements of the European Union and is placed on the
market accordingly. It has been constructed in accordance with good engineering
practice in safety matters in force in the Community and does not endanger the safety
of persons, domestic animals or property when properly installed and maintained and
used in applications for which it was made.

Equipment Description: Q-Pod Quartz Monitor
Applicable Directives: 2006/95/EC (LVD)

2004/108/EC (General EMC)

2002/95/EC (RoHS)

Applicable Standards:

Safety: EN 61010-1:2001
Emissions: EN 61326-1:1997/A1: 1998/A2: 2001 (Radiated & Conducted Emissions)

Class A: Emissions per Table 3
(EMC – Measurement, Control & Laboratory Equipment)

Immunity: EN 61326-1:1997/A1: 1998/A2: 2001 (General EMC)
Class A: Immunity per Table A1
(EMC – Measurement, Control & Laboratory Equipment)

RoHS: Fully compliant

CE Implementation Date: April 2007 (Updated February 2011)
Authorized Representative:

Steve Schill

_________________________

Thin Film Business Line Manager

INFICON Inc.

ANY QUESTIONS RELATIVE TO THIS DECLARATION OR TO THE SAFETY OF INFICON'S PRODUCTS SHOULD BE
DIRECTED, IN WRITING, TO THE AUTHORIZED REPRESENTATIVE AT THE ABOVE ADDRESS.

Warranty

WARRANTY AND LIABILITY - LIMITATION: Seller warrants the products
manufactured by it, or by an affiliated company and sold by it, and described on
the reverse hereof, to be, for the period of warranty coverage specified below, free
from defects of materials or workmanship under normal proper use and service.
The period of warranty coverage is specified for the respective products in the
respective Seller instruction manuals for those products but shall not be less than
two (2) years from the date of shipment thereof by Seller. Seller's liability under
this warranty is limited to such of the above products or parts thereof as are
returned, transportation prepaid, to Seller's plant, not later than thirty (30) days
after the expiration of the period of warranty coverage in respect thereof and are
found by Seller's examination to have failed to function properly because of
defective workmanship or materials and not because of improper installation or
misuse and is limited to, at Seller's election, either (a) repairing and returning the
product or part thereof, or (b) furnishing a replacement product or part thereof,
transportation prepaid by Seller in either case. In the event Buyer discovers or
learns that a product does not conform to warranty, Buyer shall immediately notify
Seller in writing of such non-conformity, specifying in reasonable detail the nature
of such non-conformity. If Seller is not provided with such written notification,
Seller shall not be liable for any further damages which could have been avoided if
Seller had been provided with immediate written notification.

THIS WARRANTY IS MADE AND ACCEPTED IN LIEU OF ALL OTHER
WARRANTIES, EXPRESS OR IMPLIED, WHETHER OF MERCHANTABILITY OR
OF FITNESS FOR A PARTICULAR PURPOSE OR OTHERWISE, AS BUYER'S
EXCLUSIVE REMEDY FOR ANY DEFECTS IN THE PRODUCTS TO BE SOLD
HEREUNDER. All other obligations and liabilities of Seller, whether in contract or
tort (including negligence) or otherwise, are expressly EXCLUDED. In no event
shall Seller be liable for any costs, expenses or damages, whether direct or
indirect, special, incidental, consequential, or other, on any claim of any defective
product, in excess of the price paid by Buyer for the product plus return
transportation charges prepaid.

No warranty is made by Seller of any Seller product which has been installed,
used or operated contrary to Seller's written instruction manual or which has been
subjected to misuse, negligence or accident or has been repaired or altered by
anyone other than Seller or which has been used in a manner or for a purpose for
which the Seller product was not designed nor against any defects due to plans or
instructions supplied to Seller by or for Buyer.

This manual is intended for private use by INFICON® Inc. and its customers.
Contact INFICON before reproducing its contents.

NOTE: These instructions do not provide for every contingency that may arise in
connection with the installation, operation or maintenance of this equipment.
Should you require further assistance, please contact INFICON.

www.inficon.com [e-mail]

Chapter 1

1.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1

1.1.1 Related Manuals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-2

1.2 Instrument Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.2.1 Definition of Notes, Cautions and Warnings. . . . . . . . . . . . . . . . . . . . . . . . . 1-2

1.2.2 General Cautions and Warnings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-3

1.3 How to Contact INFICON . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4

1.3.1 Returning Your Q-pod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-4

1.4 Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4

1.5 Unpacking and Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5

1.6 Parts and Options Overview. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5

1.6.1 Base Configuration. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-5

1.6.2 Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-5

Q-pod Operating Manual

Table Of Contents

Trademarks

Disclaimer

Copyright

Introduction

Chapter 2

Quick Start

2.1 Install Software. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1

2.2 Connect the Q-pod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-1

2.3 Using the Q-pod Software . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2

2.3.1 Main Display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-2

IPN 074-547-P1B

2.3.1.1 Reading Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-2

2.3.1.2 Materials Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3

2.3.2 Setup Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3

2.3.2.1 DataLog . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3

2.3.2.2 Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-3

2.3.2.3 Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.3.2.4 Q-pods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-3

2.3.3 Graph Display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2-4

TOC - 1

Q-pod Operating Manual

Chapter 3

Communications

3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3.2 ASCII Command Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1

3.3 QPOD.DLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

3.3.1 Registering QPOD.DLL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2

3.3.2 Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3

3.3.3 Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

3.4 Calculating Rate and Thickness. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

3.5 Sample Programs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4

Chapter 4

Troubleshooting and Maintenance

4.1 Troubleshooting Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.1.1 Status LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.1.1.1 LED illuminated steady. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.1.1.2 LED flashes slowly (about 2 Hz) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.1.1.3 LED flashes rapidly (about 10 Hz) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1

4.1.2 Troubleshooting the Q-pod. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2

4.1.3 Troubleshooting Sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3

4.1.4 Troubleshooting Computer Communications. . . . . . . . . . . . . . . . . . . . . . . . 4-8

4.2 Replacing the Crystal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8

4.2.1 Front Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9

4.2.2 Cool Drawer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10

4.2.3 Bakeable Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12

4.2.4 Sputtering Sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13

4.2.5 Crystal Snatcher. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14

4.3 Crystal Sensor Emulator IPN 760-601-G2 . . . . . . . . . . . . . . . . . . . . . . . . . 4-15

4.3.1 Diagnostic Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16

4.3.1.1 Measurement System Diagnostic Procedure. . . . . . . . . . . . . . . . . . . . . . . 4-16

4.3.1.2 Feed-Through Or In-Vacuum Cable Diagnostic Procedure . . . . . . . . . . . . 4-17

4.3.1.3 Sensor Head Or Monitor Crystal Diagnostic Procedure. . . . . . . . . . . . . . . 4-18

4.3.1.4 System Diagnostics Pass But Crystal Fail Message Remains. . . . . . . . . . 4-19

4.3.2 Sensor Cover Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20

4.3.2.1 Compatible Sensor Heads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20

4.3.2.2 Incompatible Sensor Heads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20

IPN 074-547-P1B

TOC - 2

4.3.3 Emulator Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-21

Chapter 5

5.1 Importance of Density, Tooling and Z-Ratio. . . . . . . . . . . . . . . . . . . . . . . . . 5-1

5.2 Determining Density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-1

5.3 Determining Tooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-2

5.4 Laboratory Determination of Z-Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5-2

Chapter 6

6.1 Basics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

6.1.1 Monitor Crystals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-2

6.1.2 Period Measurement Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-4

6.1.3 Z-match Technique. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6-5

6.1.4 Active Oscillator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-6

Appendix A

A.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .A-1

Q-pod Operating Manual

Calibration Procedures

Measurement and Theory

Material Table

IPN 074-547-P1B

TOC - 3

Q-pod Operating Manual

This page is intentionally blank.

TOC - 4

IPN 074-547-P1B

1.1 Introduction

The INFICON Q-pod™ Transducer is a small, inexpensive and accurate way to
measure thin film depositon rate and thickness. No external oscillator or power
source is required.

The included Q-pod software displays rate, thickness, frequency, crystal life and a
graph of rate versus time, for up to 8 Q-pods simultaneously. Q-pod readings can
be logged to disk in spreadsheet friendly comma-delimited format.

There are also sample files included, written in Labview, Java and Visual Basic to
help aid in the integration of the Q-pod into a system that is managed via software.
See section section 3.5, Sample Programs, on page 3-4 for more details.

Figure 1-1 Q-pod

Q-pod Operating Manual

Chapter 1

Introduction

IPN 074-547-P1B

When reading this Q-pod manual, please pay particular attention to the NOTES,
CAUTIONS, and WARNINGS found throughout the text. The Notes, Cautions, and
Warnings are defined in section 1.2.1 on page 1-2. Also, note the general warnings
in section 1.2.2, General Cautions and Warnings, on page 1-3.

1 - 1

Q-pod Operating Manual

CAUTION

WARNING

WARNING - Risk Of Electric Shock

1.1.1 Related Manuals

Sensors are covered in separate manuals. PDF files of these manuals are
contained in the 074-5000-G1 CD, part of the Ship Kit.

 074-154 - Bakeable Sensor

 074-156 - Front Load Sensor, Single/Dual

 074-157 - Sputtering Sensor

 147-800 - Cool Drawer Sensor, Single/Dual

1.2 Instrument Safety

1.2.1 Definition of Notes, Cautions and Warnings

When using this manual, please pay attention to the NOTES, CAUTIONS and
WARNINGS found throughout. For the purposes of this manual they are defined as
follows:

NOTE: Pertinent information that is useful in achieving maximum instrument

efficiency when followed.

Failure to heed these messages could result in damage
to the instrument.

Failure to heed these messages could result in personal
injury.

Dangerous voltages are present which could result in
personal injury.

IPN 074-547-P1B

1 - 2

1.2.2 General Cautions and Warnings

CAUTION

WARNING

CAUTION

Do not open the instrument case! There are no
user-serviceable components within the instrument
case.

Refer all maintenance to technically qualified personnel.

Failure to operate the Q-pod in the manner intended by
INFICON can circumvent the safety protection provided
by the instrument and may result in personal injury.

Q-pod Operating Manual

Q-pod may not be suitable for use with RF sputtering
systems or other electrically noisy environments.

IPN 074-547-P1B

1 - 3

Q-pod Operating Manual

1.3 How to Contact INFICON

Worldwide customer support information is available under Support at

www.inficon.com where you can contact:

 A Technical Support Engineer with questions regarding applications for and

programming the Q-pod.

 A Service Engineer with questions regarding troubleshooting, diagnosing or

repairing a defective Q-pod.

 Sales and Customer Service, to find the INFICON Sales office nearest to you.
 Repair Service, to find the INFICON Service Center nearest to you.

If you are experiencing a problem with your Q-pod, please have the following
information readily available:

 The serial number and firmware version for your Q-pod.
 A description of your problem.
 An explanation of any corrective action that you may have already attempted.
 The exact wording of any error messages that you may have received.

1.3.1 Returning Your Q-pod

Do not return any component of your Q-pod to INFICON without first speaking with
a Customer Support Representative. You must obtain a Return Material
Authorization (RMA) number from the Customer Support Representative.

If you deliver a package to INFICON without an RMA number, your package will be
held and you will be contacted. This will result in delays in servicing your Q-pod.

1.4 Specifications

Frequency Range. . . . . . . . . . . . . . . 1 to 6 MHz

Frequency Resolution . . . . . . . . . . . 0.05 Hz at 6 MHz @ 2 measurements per

Frequency Accuracy . . . . . . . . . . . . 0.002%

Frequency Stability. . . . . . . . . . . . . . ±2 ppm total, over 0º to 50ºC

Thickness & Rate Resolution . . . . . . 0.0613 Å (new crystal); 0.1091 Å (crystal @

Input . . . . . . . . . . . . . . . . . . . . . . . . . BNC

second)

4.5 MHz); over 500 ms sample for material
density = 1.0, Z-ratio = 1.0

IPN 074-547-P1B

1 - 4

Interface & Power. . . . . . . . . . . . . . . USB, v2.0 or later, 15 ft. (457 cm) maximum

allowable length

Size . . . . . . . . . . . . . . . . . . . . . . . . . 1 in. x 2 in. x 2.5 in. (25 mmx 50 mm x 64 mm)

Weight . . . . . . . . . . . . . . . . . . . . . . . 2 oz. (32 gm)

Computer Requirements . . . . . . . . . Any PC running Windows® XP / 2000 /

1.5 Unpacking and Inspection

1 If the Q-pod has not been removed from its packaging, do so now.

2 Carefully examine the card for damage that may have occurred during

shipping. This is especially important if you notice obvious rough handling on
the outside of the container. Immediately report any damage to the carrier and

to INFICON.

3 Do not discard the packing materials until you have taken inventory and have

at least performed successful installation.

4 Take an inventory of your order by referring to your order invoice and the

information contained in section 1.6.1.

5 To install the Q-pod, see Chapter 2, Quick Start.

Q-pod Operating Manual

Windows 7 32-bit with one available USB
port for each Q-pod

6 For additional information or technical assistance, contact INFICON, refer to

section 1.3 on page 1-4.

1.6 Parts and Options Overview

1.6.1 Base Configuration

Q-pod Transducer w/Software . . . . . . . . .Q-POD

10 ft. USB Cable. . . . . . . . . . . . . . . . . . . .068-0472

6 in. BNC Cable . . . . . . . . . . . . . . . . . . . .755-257-G6

Technical Manual . . . . . . . . . . . . . . . . . . .074-547 on 074-5000-G1 CD

IPN 074-547-P1B

1.6.2 Sensors

5.5 MHz Test Crystal . . . . . . . . . . . . . . . .782-902-023

Front Load Single Sensor. . . . . . . . . . . . . . . . . . . . . SL-XXXXX

Cool Drawer Single Sensor . . . . . . . . . . . . . . . . . . . CDS-XXFXX

Sputtering Sensor. . . . . . . . . . . . . . . . . . . . . . . . . . . 750-618-G1

Front Load UHV Bakeable Sensor . . . . . . . . . . . . . . BK-AXF

NOTE: Multi-crystal (rotary) sensors & dual sensors should not be used with the

Q-pod.

1 - 5

Q-pod Operating Manual

This page is intentionally blank.

1 - 6

IPN 074-547-P1B

2.1 Install Software

NOTE: If this is the initial Q-pod installation on this computer, you should install the

Q-pod Software before connecting a Q-pod to the USB port.

1 Place the INFICON Program Disk in the computer’s CD-ROM.

2 Ignore the prompt and double-click the My Computer icon.

3 Right-click the CD-ROM icon, then click Open.

4 Double-click the Q-pod Transducer file.

5 Double click QPOD_V#_SETUP.EXE.

6 Follow the on screen directions and select the default installation options.

7 When software installation is complete, exit the installation program.

Q-pod Operating Manual

Chapter 2

Quick Start

2.2 Connect the Q-pod

1 Connect the USB cable to a computer USB port, then to the Q-pod. See Figure

2-1.

1a If you are prompted to install the Q-pod drivers, select Install the Software

Automatically.

1b If you are prompted concerning Windows Logo Testing, select Continue

Anyway.

Figure 2-1 Q-pod Connections

IPN 074-547-P1B

2 - 1

Q-pod Operating Manual

2 Use the 6 in. BNC cable provided to connect the Q-pod to the QCM sensor

feedthrough.

3 The status light on the Q-pod illuminates when a quartz crystal is detected.

2.3 Using the Q-pod Software

Click the Q-pod desktop icon, or click Start >> Programs >> Sigma Instruments
>> Q-pod. If you are prompted to assign Q-pod(s) to a channel, click Yes. Click
Help to get more detailed information on materials and operation. Select Setup or
Graph on the Main Screen menu to change the main screen display mode. See

Figure 2-2.

Figure 2-2 Main Screen

2.3.1 Main Display

The top of the main screen is the main display. Here the Start button is used to start
and record a run. Run time and run number are shown, along with the current time
and date. The option to datalog during any given run is also given.

2.3.1.1 Reading Grid

The left grid displays the measured values of each connected Q-pod. Click Start to
display Rate and Thickness readings. Frequency and Life readings are always
displayed. Click a channel’s Zero button to zero the channel thickness reading.
Shift-Click any channel Zero button to zero all thicknesses.

2 - 2

IPN 074-547-P1B

2.3.1.2 Materials Grid

In the right grid, edit the Density, Z-Factor and Tooling values for the materials
being deposited. Move your mouse over each setting to see a brief description.

2.3.2 Setup Display

The lower section of the main screen is where run parameters can be changed and
Q-pod communication information is presented.

2.3.2.1 DataLog

Sets the file name, location and operation of disk data logging. Data log files can
be set to overwrite the file name each time it is saved. It can append the data, by
adding the newly recorded data to the end of the same file. It can also save each
run in a new file designated by run number. Data is saved in comma delimited
format for easy import into a spreadsheet.

2.3.2.2 Measurement

Sets the basic measurement parameters for all Q-pods. The values shown above
are correct for most applications.

Q-pod Operating Manual

2.3.2.3 Display

Sets the display parameters.Thickness can be displayed in kÅ or Å. Mass can be
displayed in ug/cm

2

. Rate will be changed to ng/cm2/sec if mass is the chosen
option. Resolution of displayed readings may also be changed here (0.0 or 0.00).
The rate reading filter can be set in this section. The Filter number represents how
many measurements are averaged together to produce the displayed rate. The
number of Q-pods being used is defined in this section as well.

2.3.2.4 Q-pods

Sets the name and displays the serial number of the Q-pod assigned to each
measurement channel. A strike-through serial number indicates the Q-pod is not

IPN 074-547-P1B

connected. The software can monitor a maximum of 8 Q-pods simultaneously.

2 - 3

Q-pod Operating Manual

2.3.3 Graph Display

Figure 2-3 Graph Display

Graphs the deposition rate, thickness, or frequency of active measurement
channels when Start is clicked. The graph viewed can be changed from the view
option on the toolbar on the main screen. Settings to the right of the graph control
basic graph functions. See the Help menu for advanced graph setup.

2 - 4

IPN 074-547-P1B

3.1 Introduction

The Q-pod communicates via a USB (or USB2) port and a simple ASCII command
set. An ActiveX DLL (Qpod.DLL) provides functions to set parameters, take
readings, and handle USB communications.

3.2 ASCII Command Set

The commands below assume you can open the proper USB port for
communications. The section on Qpod.DLL provides the tools needed to
communicate with the Q-pod without knowledge of USB functions.

A Q-pod command consists of an exclamation character (&H21), then the
command as detailed below, and terminated with a Carriage Return (&H13) and
Line Feed (&H10). The response has the same format, that is !<response>CrLf.

Q-pod Operating Manual

Chapter 3

Communications

@ Get version

Returns: Qpod VX.XX

A# Get Frequency and Set Status LED

Returns frequency counts. The B & C commands (see below) must be used to
set the measurement period before using this command. The response is gate
counts, which are converted crystal frequency using:

Freq = 200 MHz * GatePeriod / Response

A response of –1 indicates that a new reading is not available.

The value sent with this command activates the Status LED. Send A1 to turn
on the LED (crystal good), or A0 to cause the LED to flash at the measurement

IPN 074-547-P1B

rate (crystal fail).

B# Set Gate Period

Sets the longest measurement period, determined by the lowest valid crystal
frequency. If the desired measurement period is 0.25 seconds, and the
minimum crystal frequency is 5.0MHz, then the command is: B1250000 (0.25
x 5MHz).

C# Set Measurement Period

The value sent is the period in seconds times the reference oscillator frequency,
50MHz. If the desired measurement period is 0.25 seconds, then the command
is:

C12500000 (0.25 x 50MHz)

3 - 1

Q-pod Operating Manual

3.3 QPOD.DLL

QPOD.DLL is an Active-X DLL that provides the functions necessary to get rate
and thickness readings from up to 32 Q-pods.

In the function listings that follow, parameter and return value types are indicated
by the first letter of the variable name:

i: Integer (16 bits) f: Float (single) c: Char (8 bits) s: String

l: Long (32 bits) d: Double b: Byte (8 bits)

Functions parameters are passed By Value unless specifically designated as
ByReference (pointer).

Unless noted otherwise, the return values of functions are:

QPOD_SUCCESS = &H0 . . . . . . . . . Command successful

QPOD_BUSY = &H1. . . . . . . . . . . . . Communications already in progress

QPOD_TIMEOUT = &H2 . . . . . . . . . Did not respond

QPOD_NOREADING = &H3 . . . . . . No new reading ready

QPOD_OVERFLOW = &H4 . . . . . . Internal overflow error

QPOD_BADPARAM = &H5. . . . . . . Bad parameter value

QPOD_BADCMD = &H6 . . . . . . . . . Bad command

QPOD_BADSERNUM = &H7 . . . . . Serial number not connected

QPOD_XTALFAIL = &H8 . . . . . . . . . Crystal fail

QPOD_COMMERR = &H9 . . . . . . . . Unknown communications error

QPOD_UNKERR = &H99 . . . . . . . . . Unknown program error

3.3.1 Registering QPOD.DLL

QPOD.DLL and ccrpTmr.DLL (used for timing functions) must be registered by
Windows. The QpodDLL setup program installs and registers both files. To install
and register them manually, copy both files to the Windows\System32 folder.
Click Start, Run, and type

regsvr32\windows\system32\qpod.dll

click OK, then type

regsvr32\windows\system32\ccrpTmr.dll

IPN 074-547-P1B

3 - 2

and click OK.

3.3.2 Functions

FindQpods (By Ref sSNArray(0 to 32)) [=lRtnVal]

Searches for Q-pods connected to the computer. Populates sSNArray() with
the serial numbers of up to 32 Q-pods. Return value is total number of Q-pods
found.

Most QPOD.DLL functions require the serial number of a Q-pod as their first
parameter. FindQpods should the first function called. Additional calls to
FindQpods can be made, but be sure to resend the parameters (period,
density, etc.) for each Q-pod serial number you will use.

InitFreq (dFmax, dFmin, dFinit) [=lRtnVal]

Initializes the maximum, minimum, and initial crystal frequency values for all
attached Q-pods. The default values are Fmax=6.1 MHz, Fmin=5.0 MHz,
Finit=6.0 MHz,. Crystal readings >Fmax or <Fmin will generate a crystal fail
response to the GetReadings call. Call InitFreq immediately after FindQpods.

GetReading (sSerNum, By Ref dRdgArray(0 to 3)) [=lRtnVal]

Populates dRdgArray with the Rate, Thickness, Frequency, and %Life for the
Q- pod serial number. Thickness is returned in kA.

Q-pod Operating Manual

You can call get readings and test the return value to see if a new readings was
ready (&H0) or not (&H3). Alternatively, you can set the Reading Timer and
QPOD.DLL will raise a QpodReading event when a reading is ready. See
SetReading Timer() and QpodReading() below.

Material (sSerNum, dDensity, dZFactor, dTooling) [=lRtnVal]

Sets the Density, Z Factor, and Tooling used to convert frequency change into
rate and thickness.

Period (sSerNum, dPeriod) [=lRtnVal]

Sets the measurement period in seconds. Valid values are 0.1 to 2.

IPN 074-547-P1B

SetReadingsTimer (dInterval) [=lRtnVal]

Sets the interval for polling Qpods for readings in milliseconds. A value of zero
disables the QpodReadings event (see below).

Zero (sSerNum) [=lRtnVal]

Sets the Q-pod thickness reading to zero.

ZeroAll () [=lRtnVal]

Sets all attached Q-pod thickness readings to zero.

Revision (sSerNum, ByRef sRev) [=lRtnVal]

Returns the firmware revision in sRev. A sRev value is: Qpod V1.00.

3 - 3

Q-pod Operating Manual

3.3.3 Events

QpodReading (sSerNum, ByRef dRdgArray(0 to 3), Time)

If SetReadingsTimer (see above) is passed a non-zero interval, the QPOD.DLL
will poll every attached Q-pod for readings at the set interval.

For each Q-pod that has a new reading, a QpodReading event is raised. The
sSerNum parameter is the serial number of the Q-pod with a new reading. The
array dRdgArray holds Rate, Thickness, Frequency, and %Life for that Q-pod
serial number. Thickness is returned in kA.

3.4 Calculating Rate and Thickness

In the Q-pod software, thickness and rate are calculated using the Z-match
equation. The calculation can be divided into four parts:

1 Calculate Thickness:

Thickness = (AT_CONST * DENS_QUARTZ) / (PI * Density * Freq * ZRatio)

where AT_CONST = 16.68 x 10
Freq is the frequency calculated from the A command.

12

, DENS_QUARTZ= 2.648, PI=3.1416,

2 Correct for Z-Ratio:

Thickness

where Thickness was calculated in step 1 and FreqInit is the initial (new)
crystal frequency – typically 6MHz.

= Thickness * ArcTan(ZRatio * Tan(PI * (FreqInit - Freq) / FreqInit))

z

3 Correct for Tooling:

Thickness

= Thickness

T

4 Calculate Rate:

Rate = (Thickness

where Thickness
measurement, and Period is the elapsed time between measurements.

3.5 Sample Programs

On the INFICON CDROM in D:\Qpod Transducer_V100_SAMPLES.exe, run this
executable to set up the sample files for the Q-pod. When complete, they will be
located here: C:\Program Files\Sigma Instruments\Q-pod\Sample Programs.
These are sample interface files for use in Visual Basic and LabVIEW. These files
are meant to act as means to aid the user in creating their own software and to
allow the user to interface to the Q-pod with other devices in your operation.

* Tooling * 0.01

z

– Thickness

T

was calculated in step 3, Thickness

T

) / Period

T-1

was from the last

T-1

IPN 074-547-P1B

3 - 4

NOTE: For the sample programs to work correctly, you should also install Sigma's

Q-pod application.

Q-pod Operating Manual

Before using the LabVIEW demo, it may be best to familiarize oneself with
operation of the Q-pod software. To run the LabVIEW demo(qpod.vi), click "Load
DLL", "Use Card" and then set the Sensor parameters as desired. Click "Start" to
display readings. Be sure to click "Unload DLL" before stopping the LabVIEW
program. Otherwise, a Windows error may occur, and LabVIEW may shut down.
LabVIEW 6 or higher is required.

NOTE: The sample LabView VI may require that you select the proper DLL for the

two Automation RefNum controls. Right click each control, then click
Select ActiveX Class. Check Show Creatable Objects Only, then select
Sigma Instruments Qpod ActiveX DLL.

Figure 3-1 Labview Sample Program

IPN 074-547-P1B

3 - 5

Q-pod Operating Manual

This page is intentionally blank.

3 - 6

IPN 074-547-P1B

Troubleshooting and Maintenance

CAUTION

4.1 Troubleshooting Guide

If the Q-pod fails to function, or appears to have diminished performance, the
following Symptom/Cause/Remedy charts may be helpful.

There are no user serviceable components within the
Q-pod case.

Refer all maintenance to qualified personnel.

Q-pod Operating Manual

Chapter 4

4.1.1 Status LED

If there is a problem with the Q-pod, the status LED will indicate as to the likely
cause.

4.1.1.1 LED illuminated steady

 Good crystal detected

4.1.1.2 LED flashes slowly (about 2 Hz)

 No crystal connected

 Crystal frequency range not set correctly in software

 Crystal failure

IPN 074-547-P1B

4.1.1.3 LED flashes rapidly (about 10 Hz)

 Software not installed

 Driver not installed

 Q-pod not detected by software

 Q-pod not assigned to a sensor channel (click Find to locate Q-Pod and then

follow instructions to assign Q-Pod to a sensor channel)

 Q-pod hardware failure

4 - 1

Q-pod Operating Manual

4.1.2 Troubleshooting the Q-pod

Table 4-1 General Troubleshooting

SYMPTOM CAUSE REMEDY

1. Crystal fail message is
always on.

a. Q-pod and/or sensor not
connected.

a. Verify proper
Q-pod/sensor connections.

b. Q-pod malfunctioning. b. If available, insert a known

working Q-pod, or other
monitor, in place of suspect
one; if Q-Pod is confirmed
bad, contact INFICON
service department.

c. Defective cable from
feedthrough to Q-pod.

c. Use an Ohm meter or
DMM to check electrical
continuity or isolation as
appropriate.

d. Poor electrical contact in
the sensor, feedthroughs, or
in-vacuum cable.

d. Use an Ohm meter or
DMM to check electrical
continuity or isolation as
appropriate.

e. Failed crystal/no crystal. e. Replace crystal with new

INFICON crystal.

f. Two crystals placed into the
crystal holder.

f. Remove one of the
crystals.

g. Frequency of crystal out of
range,

g. Verify that the crystal
frequency is within the
required range, use
INFICON crystals. Set the
desired range on the main
screen on the software.

IPN 074-547-P1B

4 - 2

Table 4-1 General Troubleshooting

SYMPTOM CAUSE REMEDY

Q-pod Operating Manual

2. Noisy signal a. Distance from sensor to

3. Frequency reading is
unstable or drifting

4.1.3 Troubleshooting Sensors

NOTE: Many sensor head problems may be diagnosed with a DMM (Digital

Multi-Meter). Disconnect the short oscillator cable from the feedthrough
and measure the resistance from the center pin to ground. If the reading is
less than 10 megohms, the source of the leakage should be found and
corrected. Likewise, with the vacuum system open check for center
conductor continuity, a reading of more than 1 ohm from the feedthrough
to the Q-pod indicates a problem. Cleaning contacts or replacing the
in-vacuum cable may be required.

Q-pod is longer than 40 in.
(101.6 cm).

b. Mechanical/electric noise
sources located near the
Q-pod/cable .

a. Temperature (of the
crystal) is changing. An
AT-cut crystal frequency may
drift as much as 10 Hz/°C.

b. Humidity (level on the
crystal) is changing. Moisture
being absorbed or exuded
from the crystal surface,

a. Replace cables to
preserve the maximum
allowable length.

b. Look for potential noise
sources. Reposition the
Q-pod/cables accordingly.

a. Control the temperature of
the chamber. Check watering
cooling for flow and
temperature. Check source
to crystal distance (12 in. is
ideal).

b. Control the humidity of the
chamber.

A somewhat more thorough diagnosis may be performed with the optional

IPN 074-547-P1B

Crystal Sensor Emulator, 760-601-G1. See section 4.3 on page 4-15 for a
discussion of its use and diagnostic capabilities.A more detailed
troubleshooting guide is shipped with the sensor. Refer to that manual for
more detailed information in some cases

.

4 - 3

Q-pod Operating Manual

Table 4-2 Troubleshooting Sensors

SYMPTOM CAUSE REMEDY

1. Large jumps of thickness
reading during deposition.

a. Mode hopping. a. Mode hopping is a

byproduct of active
oscillation with a heavily
damped crystal. Temperature
stabilization is key in
diminishing this. Replace the
crystal.

b. Stress causes film to peel
from crystal surface.

b. Replace crystal or use
high performance
RunSaver™ crystal; consult
factory.

c. Particulate or "spatter"
from molten source striking
crystal.

c. Thermally condition the
source thoroughly before
deposition, use a shutter to
protect the crystal during
source conditioning.

d. Material build up,
scratches or foreign particles
on the crystal holder seating

d. Clean and polish the
crystal seating surface on the

crystal holder.
surface (improper crystal
seating.)

e. Small pieces of material
fell on crystal (for crystal
facing up sputtering
situation.)

f. Small pieces of magnetic
material being attracted by
the sensor magnet and
contacting the crystal
(sputtering sensor head.)

e. Check the crystal surface

and blow it off with clean air.

f. Check the sensor cover's

aperture and remove any

foreign material that may be

restricting full crystal

coverage.

IPN 074-547-P1B

4 - 4

Table 4-2 Troubleshooting Sensors

SYMPTOM CAUSE REMEDY

Q-pod Operating Manual

2. Crystal ceases to oscillate
during deposition before it
reaches the end of its normal
life.

a. Crystal struck by
particulate or spatter from
molten source.

a. Thermally condition the
source thoroughly before
deposition, use a shutter to
protect the crystal during
source conditioning.

b. Material on crystal holder

b. Clean crystal holder.
partially masking crystal
cover aperture.

c. Existence of electrical
short or open condition.

c.Using an ohm meter or

DMM, check for electrical

continuity in the sensor

cable, connector, contact

springs, connecting wire

inside sensor, and

feedthroughs.

d. Thermally induced

d. See 2c above.
electrical short or open
condition.

NOTE: Crystal life is highly dependent on process conditions of rate, power radiated from
source, location, material, and residual gas composition.

3. Crystal does not oscillate
or oscillates intermittently
(both in vacuum and in air.)

a. Intermittent or poor
electrical contact (contacts
oxidized.)

b. Leaf springs have lost
retentivity (ceramic retainer,
center insulator.)

a. Use an Ohm meter or

DMM to check electrical

continuity, clean contacts.

b. Carefully bend leaves to

approx. 45° on ceramic

retainer and 60° inside the

sensor head.

c. RF interference from

IPN 074-547-P1B

sputtering power supply.

c. Verify earth ground, use

ground strap adequate for

RF ground, change location

of Q-pod and cabling away

from RF power lines.

d. Cables not connected, or
connected to wrong sensor
input.

d. Verify proper connections,

and inputs relative to

programmed sensor

parameter.

4 - 5

Q-pod Operating Manual

Table 4-2 Troubleshooting Sensors

SYMPTOM CAUSE REMEDY

4. Crystal oscillates in
vacuum but stops oscillation
after open to air.

5. Thermal instability: large
changes in thickness reading
during source warm-up
(usually causes thickness
reading to decrease) and
after the termination of
deposition (usually causes
thickness reading to
increase.)

a. Crystal was near the end
of its life; opening to air
causes film oxidation which
increases film stress.

b. Excessive moisture
accumulates on the crystal.

a. Inadequate cooling
water/cooling water
temperature too high.

b. Excessive heat input to the
crystal.

c. Crystal not seated properly
in holder.

a. Replace crystal.

b. Turn off cooling water to
sensor prior to venting, flow
warm water through sensor
while chamber is open.

a. Check cooling water flow
rate, be certain that cooling
water temperature is less
than 30°C; refer to
appropriate sensor manual.

b. If heat is due to radiation
from the evaporation source,
move sensor further away
from source and use silver
crystals for better thermal
stability; install radiation
shield.

c. Clean or polish the crystal
seating surface on the crystal
holder.

d. Crystal heating caused by
high energy electron flux
(often found in RF
sputtering.)

e. Poor thermal transfer
(Bakeable.)

d. Use a sputtering sensor
head.

f. Use Al or Au foil washer
between crystal holder and
sensor body.

IPN 074-547-P1B

4 - 6

Table 4-2 Troubleshooting Sensors

SYMPTOM CAUSE REMEDY

Q-pod Operating Manual

6. Poor thickness
reproducibility.

a. Variable source flux
distribution.

a. Move sensor to a more

central location to reliably

sample evaporant, ensure

constant relative pool height

of melt, avoid tunneling into

the melt.

b. Sweep, dither, or position
where the electron beam
strikes the melt has been
changed since the last
deposition.

b. Maintain consistent source

distribution by maintaining

consistent sweep

frequencies, sweep

amplitude and electron beam

position settings.

c. Material does not adhere
to the crystal.

c. Make certain the crystal

surface is clean; avoid

touching crystal with fingers,

make use of an intermediate

adhesion layer.

d. Cyclic change in rate. d. Make certain source's

sweep frequency is not

"beating" with the Q-pod’s

measurement frequency.

7. Large drift in thickness
(greater than 200 Å for a
density of 5.00 g/cc) after
termination of sputtering.

a. Crystal heating due to poor
thermal contact.

b. External magnetic field
interfering with the sensor's
magnetic field (sputtering
sensor.)

a. Clean or polish the crystal

seating surface on the crystal

holder.

b. Rotate sensor magnet to

proper orientation with

external magnetic field, refer

to the sputtering sensor

manual IPN 074-157.

IPN 074-547-P1B

c. Sensor magnet cracked or
demagnetized (sputtering
sensor.)

c. Check sensor magnetic

field strength, the maximum

field at the center of the

aperture should be 700

gauss or greater.

4 - 7

Q-pod Operating Manual

CAUTION

4.1.4 Troubleshooting Computer Communications

Table 4-3 Troubleshooting Computer Communications

SYMPTOM CAUSE REMEDY

1. Communications cannot
be established between the
host computer and the
Q-pod.

4.2 Replacing the Crystal

Always use clean nylon lab gloves and plastic tweezers
for handling the crystal (to avoid contamination which
may lead to poor adhesion of the film to the electrode).

Do not rotate the ceramic retainer assembly after it is
seated (as this will scratch the crystal electrode and
cause poor contact).

a. Improper cable
connection.

b. Driver not installed
properly.

a. Verify for cable
connections are seated
properly.

b. Reinstall drivers. Confirm
the operating sytem is an
accepted OS. If autorun
driver install feature does
not work, the driver can be
installed from the device
manager manually.

4 - 8

Do not use excessive force when handling the ceramic
retainer assembly since breakage may occur.

NOTE: Certain materials, especially dielectrics, may not adhere strongly to the

crystal surface and may cause erratic readings.

NOTE: Thick deposits of some materials, such as SiO, Si, and Ni will normally peel

off the crystal when it is exposed to air, as a result of changes in film stress
caused by gas absorption. When you observe peeling, replace the
crystals.

IPN 074-547-P1B

4.2.1 Front Load

Front Load Crystal Holder
(IPN 750-172-G1)

Front Load Standard
Crystal Sensor Body
(IPN 750-207-G1)

Crystal (IPN 008-010-G10)
Fully Coated Face (Gold)

Finger Spring Contact

(IPN 750-171-P1)

Crystal Retainer
(IPN 007-023)

In-Vacuum Cable
To X IU

Water Tubes

Follow the procedure below to replace the crystal in the Front Load sensor: (see

Figure 4-1)

1 Gripping the crystal holder with your fingers, pull it straight out of the sensor

body.

2 Gently pry the crystal retainer from the holder (or use the Crystal Snatcher; see

Figure 4-6 on page 4-14).

3 Turn the retainer over and the crystal will drop out.

4 Install a new crystal, with the patterned electrode face up.

5 Push the retainer back into the holder and replace the holder in the sensor

body.

Figure 4-1 Front Load Crystal Sensor (Exploded)

Q-pod Operating Manual

IPN 074-547-P1B

4 - 9

Q-pod Operating Manual

Contact Spring

4.2.2 Cool Drawer

Follow the procedure below to replace the crystal in a Next Generation Cool
Drawer™ sensor:

1 Using your thumb and index fingers, gently squeeze the sides of the retainer at

the mid section then lift it up, away from the drawer, as shown in Figure 4-2.

2 Hold the drawer by the handle and turn it upside down to remove the spent

crystal.

3 Install a new crystal in the drawer. Observe its orientation. The pattern

electrode should face upward as shown in Figure 4-3.

4 Hold the retainer by its sides. Align its orientation notch with the drawer then

gently and evenly push the retainer down until it snaps firmly into the drawer.
see Figure 4-3. Never push down (or pull up) on the contact spring, doing so
may permanently damage it.

5 Inspect the whole assembly. The retainer should be even and engage the

drawer at all four corners.

Figure 4-2 Cool Drawer - Removing The Crystal

4 - 10

IPN 074-547-P1B

Figure 4-3 Cool Drawer - Replacing The Crystal

Orientation

Notch

Handle

Retainer

Crystal

Drawer

Q-pod Operating Manual

IPN 074-547-P1B

4 - 11

Q-pod Operating Manual

Crystal Holder and
Retainer Spring
IPN 750-218-G1

Crystal IPN 008-010-G10

Fully Coated Face (Gold)

Crystal Retainer IPN 007-064

Clamping Spring IPN 007-094

Contact IPN 007-099

Insulator IPN 007-103

Spreader Bar
IPN 007-267-P2

Shoulder Washer
IPN 007-268-P1
Two Required

Shoulder Washer
IPN 007-269-P1

Cam Mechanism
IPN 007-095

Cover IPN 007-101

4.2.3 Bakeable Sensor

For the Bakeable sensor, the procedure is the same as the Front Load sensor
except that you must first unlock the cam assembly by flipping it up. Once the
crystal has been replaced, place a flat edge of the holder flush with the cam
mechanism and lock it in place with the cam. See Figure 4-4.

Figure 4-4 Bakeable Crystal Sensor

IPN 074-547-P1B

4 - 12

4.2.4 Sputtering Sensor

Body Assembly

IPN 750-619-G1

In-Vacuum Cable Assembly
(29 in.) IPN 007-044

Ceramic Retainer

IPN 007-023

Crystal

IPN 008-009-G10

(Silver)

Crystal Holder

IPN 007-049

Sensor
Front Cover
IPN 007-047

Observe the general precautions for replacing crystals and follow the instructions
below to replace the crystal in a sputtering sensor.

1 Grip the body assembly with your fingers and pull it straight out to separate it

from the water-cooled front cover. (You may have to disconnect the sensor
cable in order to separate the parts.) See Figure 4-5.

2 Pull the crystal holder straight out from the front of the body assembly.

3 Remove the ceramic retainer from the crystal holder by pulling it straight out

with the crystal snatcher (see section 4.2.5 on page 4-14).

4 Turn the crystal holder over so that the crystal drops out.

5 Install a new crystal into the crystal holder with the patterned electrode facing

the back and contacting the leaf springs on the ceramic retainer.

6 Put the ceramic retainer back into the crystal holder and put the holder into the

body assembly of the sensor.

7 Align the position of the body assembly so that the connector matches with the

notch on the front cover of the sensor. Snap the two parts together. Reconnect
the sensor cable if it has been disconnected.

Q-pod Operating Manual

IPN 074-547-P1B

Figure 4-5 Sputtering Crystal Sensor

4 - 13

Q-pod Operating Manual

4.2.5 Crystal Snatcher

Use the crystal snatcher, supplied with the sensor, as follows:

1 Insert crystal snatcher into ceramic retainer (1) and apply a small amount of

pressure. This locks the retainer to the snatcher and allows the retainer to be
pulled straight out (2). See Figure 4-6.

2 Reinsert the retainer into the holder after the crystal has been replaced.

3 Release the crystal snatcher with a slight side-to-side motion.

Figure 4-6 Use of the Crystal Snatcher

4 - 14

IPN 074-547-P1B

4.3 Crystal Sensor Emulator

CAUTION

Female

BNC

Connector

Female

Microdot

Connector

Sensor

Cover

Connector

Thin Film

Controller

Crystal Interface

Unit (Oscillator)

Sensor Head

A

B

C

IPN 760-601-G2

NOTE: 760-601-G2 is fully compatible with all Thin Film Deposition Controllers.

The Crystal Sensor Emulator option is used in conjunction with the Thin Film
Deposition Controller to rapidly diagnose problems with the Deposition Controller's
measurement system. See Figure 4-7.

Figure 4-7 Crystal Sensor Emulator

Q-pod Operating Manual

The Crystal Sensor Emulator may be attached at various points in the
measurement system, from the oscillator to the sensor head. It provides a known
good monitor crystal with known good electrical connections. Using the emulator
and the controller in a systematic manner provides a fast means of isolating
measurement system, cable, or sensor problems. See Figure 4-8.

Figure 4-8 Crystal Sensor Emulator Attachment Points

IPN 074-547-P1B

This product is designed as a diagnostic tool, and is not
intended for use in vacuum. Do not leave the Crystal
Sensor Emulator installed in the vacuum system during
processing.

4 - 15

Q-pod Operating Manual

4.3.1 Diagnostic Procedures

The following diagnostic procedures employ the Crystal Sensor Emulator to
analyze a constant Crystal Fail message. The symptom is a Crystal Fail message
that is displayed by the Q-pod software even after the monitor crystal has been
replaced with a new good monitor crystal.

4.3.1.1 Measurement System Diagnostic Procedure

1 Refer to Figure 4-8 on page 4-15. Remove the six-inch BNC cable from the

Feed-Through at point A.

2 Connect the Crystal Sensor Emulator to the 6 inch BNC cable at Point A.

 If the Crystal Fail message disappears after approximately five seconds,

the measurement system is working properly. Re-install the six-inch BNC
cable to the Feed-Through. Go to section 4.3.1.2.

 If the Crystal Fail message remains, continue at step 3.

3 Disconnect the six-inch BNC cable from the Oscillator and from the Emulator.

4 Visually inspect the six-inch BNC cable to verify that the center pins are seated

properly.

5 Use an Ohm meter to verify the electrical connections on the six-inch BNC

cable.

 There must be continuity (<0.2 ohms, after accounting for resistance of

ohmeter leads) between the center pins.

 There must be isolation (>10 megohms) between the center pins and the

connector shield.

 There must be continuity between the connector shields.

Replace the six-inch BNC cable if it is found to be defective and repeat Step 2
of this procedure.

6 If the six-inch BNC cable is not defective, re-connect the six-inch cable to the

oscillator and to the Crystal Sensor Emulator. If the Crystal Fail message
remains, contact INFICON.

IPN 074-547-P1B

4 - 16

4.3.1.2 Feed-Through Or In-Vacuum Cable Diagnostic Procedure

1 Refer to Figure 4-8 on page 4-15. Remove the In-Vacuum cable from the

Sensor Head at point B.

2 Connect the Crystal Sensor Emulator to the In-Vacuum cable.

 If the Crystal Fail message disappears after approximately five seconds,

the Feed-Through and In-Vacuum Cable are working properly. Re-install
the In-Vacuum cable to the Sensor Head. Go to section section 4.3.1.3 on

page 4-18.

 If the Crystal Fail message remains, continue at step 3.

3 Disconnect the In-Vacuum cable from the Feed-Through and the Emulator.

Disconnect the six-inch BNC cable from the Feed-Through.

4 Using an Ohm Meter, verify electrical continuity from the BNC center pin on the

Feed-Through to the Microdot center pin on the Feed-Through. A typical value
would be less than 0.2 ohms.

5 Verify electrical isolation of the center pin on the Feed-Through from the

electrical ground (Feed-Through body). A typical value would be in excess of
10 megohms.

Q-pod Operating Manual

If the Feed-Through is found to be defective, replace the Feed-Through, re-attach
the BNC and In-Vacuum cables, and repeat this procedure starting at Step 2,
otherwise continue at step 6.

6 Verify electrical continuity from center pin to center pin on the In-Vacuum cable.

7 Verify that the center pin of the In-Vacuum cable is electrically isolated from the

In-Vacuum cable shield.

If the In-Vacuum cable is found to be defective, replace the In-Vacuum cable.
Re-attach the BNC and In-Vacuum cables, and repeat this procedure starting at
Step 2, otherwise continue at step 8.

IPN 074-547-P1B

8 Connect the In-Vacuum Cable to the Feed-Through.

9 Verify electrical continuity from the center pin on the BNC connector of the

Feed-Through to the center pin on the un-terminated end of the In-Vacuum
cable.

10 Verify electrical isolation from the center pin to electrical ground (Feed-Through

body).

If the Feed-Through/In-Vacuum cable system is found to be defective, look for
defective electrical contacts at the Feed-Through to In-Vacuum cable connection.
Repair or replace the Feed-Through as necessary. Re-attach the BNC and
In-Vacuum cables and repeat this procedure starting at step 2. Otherwise, continue
at step 11.

4 - 17

Q-pod Operating Manual

11 Connect the six-inch BNC cable to the Feed-Through and disconnect it from the

Q-pod.

12 Verify electrical continuity from the center pin of the Microdot connector on the

Feed-Through to the un-terminated end of the six-inch BNC cable.

13 Verify electrical isolation from the center pin to electrical ground (Feed-Through

body).

If the Feed-Through/six-inch BNC cable system is found to be defective, look for
defective contacts at the Feed-Through to BNC cable connection. Repair or
replace the Feed-Through as necessary, re-attach the BNC cable to the XIU and
In-Vacuum cable to the Crystal head and repeat this procedure starting at step 2.

4.3.1.3 Sensor Head Or Monitor Crystal Diagnostic Procedure

NOTE: The procedure is for use with front load style sensor heads.

1 Remove the Crystal Cover from the Sensor Head.

2 Refer to Figure 4-7 on page 4-15. Connect the Crystal Sensor Emulator to the

Sensor Head at Point C.

 If the Crystal Fail message disappears after approximately 5 seconds the

Sensor Head is operating properly. Remove the Crystal Sensor Emulator
and re-insert the Crystal Cover into the Sensor Head.

 If the Crystal Fail message remains, continue at step 3.

3 Disconnect the In-Vacuum cable from the Sensor Head and the Feed-Through.

Remove the Crystal Sensor Emulator from the Sensor Head.

4 Using an Ohm meter, verify the electrical connections on the Sensor Head.

 Verify there is electrical continuity from the center pin contact on the

Microdot connector on the Sensor Head to the leaf spring contact in the
Sensor Head. Take care not to apply to much pressure on the center pin of
the microdot connector as it may become damaged.

 There must be electrical isolation between the center pin of the Microdot

connector and the Sensor Head body.

If the Sensor Head is found to be defective, contact INFICON to have the
Sensor Head repaired.

IPN 074-547-P1B

4 - 18

5 Connect the In-Vacuum Cable to the Sensor Head.

 Verify there is continuity (<0.2 ohm) from the leaf spring contact in the

Sensor Head to the center pin on the un-terminated end of the In-Vacuum
cable.

 Verify there is isolation (>10 megohm) between the leaf spring contact and

the In-Vacuum cable shield.

If the Sensor Head or the In-Vacuum cable system is found to be defective, look for
defective contacts at the In-Vacuum cable to Sensor Head connection, repair or
replace the Sensor Head as necessary. Re-attach the In-Vacuum cable to the
Feed-Through and repeat this procedure starting at step 2.

6 Ensure that the leaf springs in the Sensor Head and those in the Ceramic

Retainer are bent to an angle of approximately 60º and 45º from flat,
respectively.

4.3.1.4 System Diagnostics Pass But Crystal Fail Message Remains

If the system is operating properly yet the Crystal Fail message is still displayed,
perform the following tasks.

Q-pod Operating Manual

1 On the Ceramic Retainer verify that the center rivet is secure. Repair or replace

the Ceramic Retainer as necessary.

2 Inspect the inside of the Crystal Holder for build-up of material. Clean or replace

the Crystal Holder as necessary.

After verifying the Sensor Head contacts, the Sensor Head/In-Vacuum cable
connection and the ceramic retainer contacts, re-assemble the system. If the
Crystal Fail message remains, replace the monitor crystal with a new monitor
crystal. Verify that the monitor crystal works properly by inserting it into a known
good measurement system. If you continue to experience problems, contact
INFICON.

IPN 074-547-P1B

4 - 19

Q-pod Operating Manual

4.3.2 Sensor Cover Connection

The Crystal Sensor Emulator can be used to verify the measurement system for
INFICON Thin Film Deposition Controllers and Monitors.

However, the Crystal Sensor Emulator's Sensor Cover Connector is compatible
with some sensor heads, and is incompatible with others. This is discussed in the
following sections.

4.3.2.1 Compatible Sensor Heads

The Sensor Cover Connection will fit the sensor heads shown in Table 4-4.

Table 4-4 Compatible Sensor Heads

Sensor Head Part Number

Front Load Single Sensor Head SL-XXXXX

Front Load Dual Sensor Head DL-AEXX

4.3.2.2 Incompatible Sensor Heads

The Sensor Heads for which the Crystal Sensor Emulator's Sensor Cover
Connector will not fit are shown in Table 4-5.

Table 4-5 Incompatible Sensor Heads

Sensor Head Part Number

Front Load UHV Bakeable Sensor Head BK-AXX

Cool Drawer Single Sensor Head CDS-XXXXX

Sputtering Sensor Head 750-618-G1

CrystalSix Sensor Head 750-446-G1

Cool Drawer Dual Sensor Head CDD-XXXX

Crystal12 Sensor Head XL12-XXXXXX

RSH-600 Sensor Head 15320X-XX

NOTE: The Crystal Sensor Emulator’s Sensor Cover will not fit the crystal holder

opening of the older style INFICON transducers that have the soldered
finger springs.

IPN 074-547-P1B

4 - 20

4.3.3 Emulator Specifications

Dimensions

1.58 in. diameter x 1.79 in.
(40.13 mm diameter x 45.47 mm)

Temperature Range

0 to 50

Frequency

760-601-G2: 5.5 MHz ± 1 ppm at room temperature

Materials

304 Stainless Steel, Nylon, Teflon®, brass. Some internal components contain
zinc, tin, and lead.

o

C

Q-pod Operating Manual

IPN 074-547-P1B

4 - 21

Q-pod Operating Manual

This page is intentionally blank.

4 - 22

IPN 074-547-P1B

Q-pod Operating Manual

Density g cm

3

D

1

T

x

T

m

-------







=

Calibration Procedures

5.1 Importance of Density, Tooling and Z-Ratio

The quartz crystal microbalance is capable of precisely measuring the mass added
to the face of the oscillating quartz crystal sensor. The Q-pod's knowledge of the
density of this added material (specified in the density parameter in material grid)
allows conversion of the mass information into thickness. In some instances, where
highest accuracy is required, it is necessary to make a density calibration as
outlined in section 5.2.

Because the flow of material from a deposition is not uniform, it is necessary to
account for the different amount of material flow onto the sensor compared to the
substrates. This factor is accounted for in the tooling parameter in material grid.
The tooling factor can be experimentally established by following the guidelines in

section 5.3 on page 5-2.

Chapter 5

If the Z-Ratio is not known, it could be estimated from the procedures outlined in

section 5.4 on page 5-2.

5.2 Determining Density

NOTE: The bulk density values retrieved from Table A-1 are sufficiently accurate

for most applications.

Follow the steps below to determine density value.

1 Place a substrate (with proper masking for film thickness measurement)

adjacent to the sensor, so that the same thickness will be accumulated on the
crystal and substrate.

2 Set density to the bulk value of the film material or to an approximate value.

IPN 074-547-P1B

3 Set Z-Ratio to 1.000 and tooling to 100%.

4 Place a new crystal in the sensor and make a short deposition

(1000-5000 Å).

5 After deposition, remove the test substrate and measure the film thickness with

either a multiple beam interferometer or a stylus-type profilometer.

6 Determine the new density value with equation [1]:

[1]

5 - 1

Q-pod Operating Manual

Tooling (%) TF

i

T

m

T

x

-------







=

where:

= Initial density setting

D

1

= Thickness reading on Q-pod

T

x

= Measured thickness

T

m

7 A quick check of the calculated density may be made by programming the

Q-pod with the new density value and observing that the displayed thickness is
equal to the measured thickness, provided that the Q-pod's thickness has not
been zeroed between the test deposition and entering the calculated density.

NOTE: Slight adjustment of density may be necessary in order to

achieve T

= Tm.

x

5.3 Determining Tooling

1 Place a test substrate in the system's substrate holder.

2 Make a short deposition and determine actual thickness.

3 Calculate tooling from the relationship shown in equation [2]:

where

T

= Actual thickness at substrate holder

m

= Thickness reading in the Q-pod

T

x

= Initial tooling factor

TF

i

4 Round off percent tooling to the nearest 0.1%.

5 When entering this new value for tooling into the program, T

calculations are done properly.

NOTE: It is recommended that a minimum of three separate evaporations be

made when calibrating tooling. Variations in source distribution and other
system factors will contribute to slight thickness variations. An average
value tooling factor should be used for final calibrations.

5.4 Laboratory Determination of Z-Ratio

A list of Z-values for materials commonly used are available in Table A-1. For other
materials, Z can be calculated from the following formula:

will equal Tx if

m

[2]

IPN 074-547-P1B

5 - 2

Q-pod Operating Manual

Z

d

qq

df

f

------------







1
2

---

=

Z 9.378 105df

f



-

1
2

---

=

T

f

Zq10

4



2zp

--------------------

1

F

co

--------





ATan zTan

F

co

F

q

-----------









1

F

c

-----





ATan zTan

F

c

F

q

---------









–







=

where:

= density (g/cm3) of deposited film

d

f

= shear modulus (dynes/cm2) of deposited film

µ

f

= density of quartz (crystal) (2.649 gm/cm3)

d

q

= shear modulus of quartz (crystal) (3.32 x 1011 dynes/cm2)

µ

q

The densities and shear moduli of many materials can be found in a number of
handbooks.

[3]

[4]

Laboratory results indicate that Z-values of materials in thin-film form are very close
to the bulk values. However, for high stress producing materials, Z-values of thin
films are slightly smaller than those of the bulk materials. For applications that
require more precise calibration, the following direct method is suggested:

1 Establish the correct density value as described in section 5.2 on page 5-1.

2 Install a new crystal and record its starting frequency, F

frequency will be displayed on the main screen.

. The starting

co

3 Make a deposition on a test substrate such that the percent crystal life display

will read approximately 50%, or near the end of crystal life for the particular
material, whichever is smaller.

4 Stop the deposition and record the ending crystal frequency F

IPN 074-547-P1B

5 Remove the test substrate and measure the film thickness with either a multiple

beam interferometer or a stylus-type profilometer.

6 Using the density value from step 1 and the recorded values for F

adjust the Z-ratio value in thickness equation [5] to bring the calculated
thickness value into agreement with the actual thickness. If the calculated value
of thickness is greater than the actual thickness, increase the Z-Ratio value. If
the calculated value of thickness is less than the actual thickness, decrease the
Z-Ratio value.

.

c

and Fc,

co

[5]

5 - 3

Q-pod Operating Manual

where:

= thickness of deposited film (kÅ)

T

f

= starting frequency of the sensor crystal (Hz)

F

co

= Final frequency of the sensor crystal (Hz)

F

c

= Nominal blank frequency = 6045000 (Hz)

F

q

z = Z-ratio of deposited film material

Z

= Specific acoustic impedance of quartz = 8765000 (MKS units)

q

p = density of deposited film (g/cc)

For multiple layer deposition (for example, two layers), the Z-value used for the
second layer is determined by the relative thickness of the two layers. For most
applications the following three rules will provide reasonable accuracies:

 If the thickness of layer 1 is large compared to layer 2, use material 1 Z-value

for both layers.

 If the thickness of layer 1 is thin compared to layer 2, use material 2 Z-value for

both layers.

 If the thickness of both layers is similar, use a value for Z-Ratio which is the

weighted average of the two Z values for deposition of layer 2 and subsequent
layers.

IPN 074-547-P1B

5 - 4

6.1 Basics

M

f

M

q

-------

F

F

q

-----------=

T

f

KF

d

f

----------------=

Q-pod Operating Manual

Chapter 6

Measurement and Theory

The Quartz Crystal deposition Monitor, or QCM, utilizes the piezoelectric sensitivity
of a quartz monitor crystal to added mass. The QCM uses this mass sensitivity to
control the deposition rate and final thickness of a vacuum deposition. When a
voltage is applied across the faces of a properly shaped piezoelectric crystal, the
crystal is distorted and changes shape in proportion to the applied voltage. At
certain discrete frequencies of applied voltage, a condition of very sharp
electro-mechanical resonance is encountered. When mass is added to the face of
a resonating quartz crystal, the frequency of these resonances are reduced. This
change in frequency is very repeatable and is precisely understood for specific
oscillating modes of quartz. This heuristically easy to understand phenomenon is
the basis of an indispensable measurement and process control tool that can easily
detect the addition of less than an atomic layer of an adhered foreign material.

In the late 1950’s it was noted by Sauerbrey
frequency, DF = F
frequencies, F

and Fq respectively, is related to the change in mass from the

c

added material, M

, of a quartz crystal with coated (or composite) and uncoated

q-Fc

, as follows:

f

1,2

and Lostis3 that the change in

[1]

where M

is the mass of the uncoated quartz crystal. Simple substitutions lead to

q

the equation that was used with the first “frequency measurement” instruments:

[2]

IPN 074-547-P1B

where the film thickness, T

, is proportional (through K) to the frequency change,

f

DF, and inversely proportional to the density of the film, d

2

N

atdq/Fq

; where dq (= 2.649 gm/cm3) is the density of single crystal quartz and Nat

. The constant, K =

f

(=166100 Hz cm) is the frequency constant of AT cut quartz. A crystal with a
starting frequency of 6.0 MHz will display a reduction of its frequency by 2.27 Hz
when 1 angstrom of Aluminum (density of 2.77 gm/cm

3

) is added to its surface. In
this manner the thickness of a rigid adlayer is inferred from the precise
measurement of the crystal’s frequency shift. The quantitative knowledge of this

1.G. Z. Sauerbrey, Phys. Verhand .8, 193 (1957)

2.G. Z. Sauerbrey, Z. Phys. 155

3.P. Lostis, Rev. Opt. 38

,206 (1959)

,1 (1959)

6 - 1

Q-pod Operating Manual

effect provides a means of determining how much material is being deposited on a
substrate in a vacuum system, a measurement that was not convenient or practical
prior to this understanding.

6.1.1 Monitor Crystals

No matter how sophisticated the electronics surrounding it, the essential device of
the deposition monitor is the quartz crystal. The quartz crystal shown in Figure 6-1
has a frequency response spectrum that is schematically shown in Figure 6-2. The
ordinate represents the magnitude of response, or current flow of the crystal, at the
specified frequency.

Figure 6-1 Quartz Resonator

The lowest frequency response is primarily a “thickness shear” mode that is called
the fundamental. The characteristic movement of the thickness shear mode is for
displacement to take place parallel to the major monitor crystal faces. In other
words, the faces are displacement antinodes as shown in Figure 6-3. The
responses located slightly higher in frequency are called anharmonics; they are a
combination of the thickness shear and thickness twist modes. The response at
about three times the frequency of the fundamental is called the third
quasiharmonic. There are also a series of anharmonics slightly higher in frequency
associated with the quasiharmonic.

The monitor crystal design depicted in Figure 6-1 is the result of several significant
improvements from the square crystals with fully electroded plane parallel faces
that were first used. The first improvement was to use circular crystals. This
increased symmetry greatly reduced the number of allowed vibrational modes. The
second set of improvements was to contour one face of the crystal and to reduce
the size of the exciting electrode. These improvements have the effect of trapping
the acoustic energy. Reducing the electrode diameter limits the excitation to the
central area. Contouring dissipates the energy of the traveling acoustic wave
before it reaches the edge of the crystal. Energy is not reflected back to the center
where it can interfere with other newly launched waves, essentially making a small
crystal appear to behave as though it is infinite in extent. With the crystal’s
vibrations restricted to the center, it is practical to clamp the outer edges of the
crystal to a holder and not produce any undesirable effects. Contouring also

IPN 074-547-P1B

6 - 2

Q-pod Operating Manual

5.981 MHz 15 ohm

6.153 MHz 50 ohm

6.194 MHz 40 ohm

6.333 MHz 142 ohm

6.337 MHz 105 ohm

6.348 MHz 322 ohm

6.419 MHz 350 ohm

17.792 MHz 278 ohm

17.957 MHz 311 ohm

18.133 MHz 350 ohm

Log of relative intensity (Admittance)

Frequency (in MHz)

1

10

1

100

1

1000

6 7 17 18

reduces the intensity of response of the generally unwanted anharmonic modes;
hence, the potential for an oscillator to sustain an unwanted oscillation is
substantially reduced.

Figure 6-2 Frequency Response Spectrum

The use of an adhesion layer has improved the electrode-to-quartz bonding,
reducing “rate spikes” caused by micro-tears between the electrode and the quartz
as film stress rises. These micro-tears leave portions of the deposited film
unattached and therefore unable to participate in the oscillation. These free
portions are no longer detected and the wrong thickness consequently inferred.

The “AT” resonator is usually chosen for deposition monitoring because at room
temperature it can be made to exhibit a very small frequency change due to
temperature changes. Since there is presently no way to separate the frequency
change caused by added mass (which is negative) or even the frequency changes
caused by temperature gradients across the crystal or film induced stresses, it is

IPN 074-547-P1B

essential to minimize these temperature-induced changes. It is only in this way that
small changes in mass can be measured accurately.

6 - 3

Q-pod Operating Manual

displacement node

X

X

X

2

1

3

E

M

f

M

q

-------

TcTq–

T

q

----------------------

F

F

c

-----------==

Figure 6-3 Thickness Shear Displacement

6.1.2 Period Measurement Technique

Although instruments using equation [2] were very useful, it was soon noted they
had a very limited range of accuracy, typically holding accuracy for DF less than

0.02 F

where T
and the bare crystal respectively. The period measurement technique was the
outgrowth of two factors; first, the digital implementation of time measurement, and
second, the recognition of the mathematically rigorous formulation of the
proportionality between the crystal’s thickness, I
= 1/F
oscillator, or reference oscillator, not affected by the deposition and usually much
higher in frequency than the monitor crystal. This reference oscillator is used to
generate small precision time intervals which are used to determine the oscillation
period of the monitor crystal. This is done by using two pulse accumulators. The
first is used to accumulate a fixed number of cycles, m, of the monitor crystal. The
second is turned on at the same time and accumulates cycles from the reference
oscillator until m counts are accumulated in the first. Since the frequency of the
reference is stable and known, the time to accumulate the m counts is known to an
accuracy equal to ± 2/F

. In 1961 it was recognized by Behrndt4 that:

q

and Tq are the periods of oscillation of the crystal with film (composite)

c

. Electronically the period measurement technique uses a second crystal

q

where Fr is the reference oscillator’s frequency. The

r

, and the period of oscillation, Tq

q

[3]

IPN 074-547-P1B

6 - 4

4.K. H. Behrndt, J. Vac. Sci. Technol. 8, 622 (1961)

Q-pod Operating Manual

T

f

Natd

q

dfFcZ

------------------





arctan Z tan

 FqFc–

F

q

-------------------------





=

monitor crystal’s period is (n/Fr)/m where n is the number of counts in the second
accumulator. The precision of the measurement is determined by the speed of the
reference clock and the length of the gate time (which is set by the size of m).
Increasing one or both of these leads to improved measurement precision.

Having a high frequency reference oscillator is important for rapid measurements
(which require short gating times), low deposition rates and low density materials.
All of these require high time precision to resolve the small, mass induced
frequency shifts between measurements. When the change of a monitor crystal’s
frequency between measurements is small, that is, on the same order of size as
the measurement precision, it is not possible to establish quality rate control. The
uncertainty of the measurement injects more noise into the control loop, which can
be counteracted only by longer time constants. Long time constants cause the
correction of rate errors to be very slow, resulting in relatively long term deviations
from the desired rate. These deviations may not be important for some simple films,
but can cause unacceptable errors in the production of critical films such as optical
filters or very thin layered superlattices grown at low rates. In many cases the
desired properties of these films can be lost if the layer to layer reproducibility
exceeds one, or two, percent. Ultimately, the practical stability and frequency of the
reference oscillator limits the precision of measurement for conventional
instrumentation.

6.1.3 Z-match Technique

After learning of fundamental work by Miller and Bolef 5, which rigorously treated
the resonating quartz and deposited film system as a one-dimensional continuous
acoustic resonator, Lu and Lewis
in 1972. Advances in electronics taking place at the same time, namely the
micro-processor, made it practical to solve the Z-match equation in “real-time”.
Most deposition process controllers/monitors sold today use this sophisticated
equation that takes into account the acoustic properties of the resonating quartz
and film system as shown in equation [4].

IPN 074-547-P1B

where Z=(d

quq/dfuf

1/2

)

is the acoustic impedance ratio and uq and uf are the shear
moduli of the quartz and film, respectively. Finally, there was a fundamental
understanding of the frequency-to-thickness conversion that could yield
theoretically correct results in a time frame that was practical for process control.
To achieve this new level of accuracy requires only that the user enter an additional
material parameter, Z, for the film being deposited. This equation has been tested

6

developed the simplifying Z-match™ equation

[4]

5.J. G. Miller and D. I. Bolef, J. Appl. Phys. 39, 5815, 4589 (1968)

6.C. Lu and O. Lewis, J Appl. Phys. 43

, 4385 (1972)

6 - 5

Q-pod Operating Manual

for a number of materials, and has been found to be valid for frequency shifts
equivalent to F
and equation [3] was valid only to ~0.05F

6.1.4 Active Oscillator

The Q-pod relies on the use of an active oscillator circuit, Specifically the type
schematically shown in Figure 6-4. This circuit actively keeps the crystal in
resonance, so that any type of period or frequency measurement may be made. In
this type of circuit, oscillation is sustained as long as the gain provided by the
amplifiers is sufficient to offset losses in the crystal and circuit and the crystal can
provide the required phase shift. The basic crystal oscillator’s stability is derived
from the rapid change of phase for a small change in the crystal’s frequency near
the series resonance point, as shown in Figure 6-6 on page 6-7.

Figure 6-4 Active Oscillator Circuit

= 0.4Fq. Keep in mind that equation [2] was valid to only 0.02Fq

f

.

q

6 - 6

The active oscillator circuit is designed so the crystal is required to produce a phase
shift of 0 degrees, which allows it to operate at the series resonance point. Long­and short-term frequency stabilities are a property of crystal oscillators because
very small frequency changes are needed to sustain the phase shift required for
oscillation. Frequency stability is provided by the quartz crystal even though there
are long term changes in electrical component values caused by temperature or
aging or short-term noise-induced phase jitter.

As mass is added to a crystal, its electrical characteristics change. Figure 6-5 on

page 6-7 is the same plot as Figure 6-6 overlaid with the response of a heavily

loaded crystal.

IPN 074-547-P1B

Q-pod Operating Manual

Figure 6-5 Heavily Loaded Crystal

The crystal has lost the steep slope displayed in Figure 6-6. Because the phase
slope is less steep, any noise in the oscillator circuit translates into a greater
frequency shift than that which would be produced with a new crystal. In the
extreme, the basic phase/frequency shape is not preserved and the crystal is not
able to provide a full 90 degrees of phase shift.

Figure 6-6 Crystal Frequency Near Series Resonance Point

IPN 074-547-P1B

The impedance, |Z|, is also noted to rise to an extremely high value. When this
happens it is often more favorable for the oscillator to resonate at one of the
anharmonic frequencies. This condition is sometimes short lived, with the oscillator
switching between the fundamental and anharmonic modes, or it may continue to
oscillate at the anharmonic. This condition is known as mode hopping and in
addition to annoying rate noise can also lead to false termination of the film
because of the apparent frequency change. It is important to note that the Q-pod
will frequently continue to operate under these conditions; in fact there is no way to
tell this has happened except that the film’s thickness is suddenly apparently
thinner by an amount equivalent to the frequency difference between the
fundamental and the anharmonic that is sustaining the oscillation.

6 - 7

Q-pod Operating Manual

This page is intentionally blank.

6 - 8

IPN 074-547-P1B

A.1 Introduction

CAUTION

The following Table A-1 represents the density and Z-Ratio for various materials.
The list is alphabetical by chemical formula.

An * is used to indicate that a Z-ratio has not been established for a certain
material. A value of 1.000 is defaulted in these situations.

Q-pod Operating Manual

Appendix A

Material Table

Some of these materials are toxic. Please consult the
material safety data sheet and safety instructions before
use.

Table A-1 Material Table

Formula Density Z-Ratio Material Name

Ag 10.500 0.529 silver

AgBr 6.470 1.180 silver bromide

AgCl 5.560 1.320 silver chloride

Al 2.700 1.080 aluminum

Al

2O3

Al

4C3

AIF

3

AIN 3.260 *1.000 aluminum nitride

IPN 074-547-P1B

AlSb 4.360 0.743 aluminum antimonide

As 5.730 0.966 arsenic

As

2Se3

Au 19.300 0.381 gold

B 2.370 0.389 boron

B

203

B

C 2.370 *1.000 boron carbide

4

BN 1.860 *1.000 boron nitride

3.970 0.336 aluminum oxide

2.360 *1.000 aluminum carbide

3.070 *1.000 aluminum fluoride

4.750 *1.000 arsenic selenide

1.820 *1.000 boron oxide

Ba 3.500 2.100 barium

BaF

2

PRELIMINARY 5/4/12 A - 1

4.886 0.793 barium fluoride

Q-pod Operating Manual

Table A-1 Material Table (continued)

Formula Density Z-Ratio Material Name

BaN2O

6

3.244 1.261 barium nitrate

BaO 5.720 *1.000 barium oxide

BaTiO

BaTiO

3

3

5.999 0.464 barium titanate (tetr)

6.035 0.412 barium titanate (cubic)

Be 1.850 0.543 beryllium

BeF

2

1.990 *1.000 beryllium fluoride

BeO 3.010 *1.000 beryllium oxide

Bi 9.800 0.790 bismuth

Bi

Bi

Bi

Bi

BiF

2O3

2S3

2Se3

2Te3

3

8.900 *1.000 bismuth oxide

7.390 *1.000 bismuth trisulphide

6.820 *1.000 bismuth selenide

7.700 *1.000 bismuth telluride

5.320 *1.000 bismuth fluoride

C 2.250 3.260 carbon (graphite)

C 3.520 0.220 carbon (diamond)

C

8H8

1.100 *1.000 parlyene (union carbide)

Ca 1.550 2.620 calcium

CaF

2

3.180 0.775 calcium fluoride

CaO 3.350 *1.000 calcium oxide

CaO-SiO

CaSO

4

CaTiO

3

CaWO

4

2.900 *1.000 calcium silicate (3)

2

2.962 0.955 calcium sulfate

4.100 *1.000 calcium titanate

6.060 *1.000 calcium tungstate

Cd 8.640 0.682 cadmium

CdF

2

6.640 *1.000 cadmium fluoride

CdO 8.150 *1.000 cadmium oxide

CdS 4.830 1.020 cadmium sulfide

CdSe 5.810 *1.000 cadmium selenide

CdTe 6.200 0.980 cadmium telluride

Ce 6.780 *1.000 cerium

CeF

CeO

3

2

6.160 *1.000 cerium (III) fluoride

7.130 *1.000 cerium (IV) dioxide

Co 8.900 0.343 cobalt

IPN 074-547-P1B

A - 2 PRELIMINARY 5/4/12

Q-pod Operating Manual

Table A-1 Material Table (continued)

Formula Density Z-Ratio Material Name

CoO 6.440 0.412 cobalt oxide

Cr 7.200 0.305 chromium

Cr

Cr

2O3

3C2

5.210 *1.000 chromium (III) oxide

6.680 *1.000 chromium carbide

CrB 6.170 *1.000 chromium boride

Cs 1.870 *1.000 cesium

Cs

2SO4

4.243 1.212 cesium sulfate

CsBr 4.456 1.410 cesium bromide

CsCI 3.988 1.399 cesium chloride

CsI 4.516 1.542 cesium iodide

Cu 8.930 0.437 copper

Cu

O 6.000 *1.000 copper oxide

2

Cu

S 5.600 0.690 copper (I) sulfide (alpha)

2

Cu

S 5.800 0.670 copper (I) sulfide (beta)

2

CuS 4.600 0.820 copper (II) sulfide

Dy 8.550 0.600 dysprosium

DY

2O3

7.810 *1.000 dysprosium oxide

Er 9.050 0.740 erbium

Er

2O3

8.640 *1.000 erbium oxide

Eu 5.260 *1.000 europium

EuF

2

6.500 *1.000 europium fluoride

Fe 7.860 0.349 iron

Fe

2O3

5.240 *1.000 iron oxide

FeO 5.700 *1.000 iron oxide

IPN 074-547-P1B

FeS 4.840 *1.000 iron sulphide

Ga 5.930 0.593 gallium

Ga

2O3

5.880 *1.000 gallium oxide (b)

GaAs 5.310 1.590 gallium arsenide

GaN 6.100 *1.000 gallium nitride

GaP 4.100 *1.000 gallium phosphide

GaSb 5.600 *1.000 gallium antimonide

Gd 7.890 0.670 gadolinium

Gd

2O3

PRELIMINARY 5/4/12 A - 3

7.410 *1.000 gadolinium oxide

Q-pod Operating Manual

Table A-1 Material Table (continued)

Formula Density Z-Ratio Material Name

Ge 5.350 0.516 germanium

Ge

3N2

GeO

2

5.200 *1.000 germanium nitride

6.240 *1.000 germanium oxide

GeTe 6.200 *1.000 germanium telluride

Hf 13.090 0.360 hafnium

HfB

2

10.500 *1.000 hafnium boride

HfC 12.200 *1.000 hafnium carbide

HfN 13.800 *1.000 hafnium nitride

HfO

HfSi

2

2

9.680 *1.000 hafnium oxide

7.200 *1.000 hafnium silicide

Hg 13.460 0.740 mercury

Ho 8.800 0.580 holminum

Ho

2O3

8.410 *1.000 holminum oxide

In 7.300 0.841 indium

In

In

In

2O3

2Se3

2Te3

7.180 *1.000 indiurn sesquioxide

5.700 *1.000 indium selenide

5.800 *1.000 indium telluride

InAs 5.700 *1.000 indium arsenide

InP 4.800 *1.000 indium phosphide

InSb 5.760 0.769 indium antimonide

Ir 22.400 0.129 iridium

K 0.860 10.189 potassium

KBr 2.750 1.893 potassium bromide

KCI 1.980 2.050 potassium chloride

KF 2.480 *1.000 potassium fluoride

KI 3.128 2.077 potassium iodide

La 6.170 0.920 lanthanum

La

LaB

LaF

2O3

6

3

6.510 *1.000 lanthanum oxide

2.610 *1.000 lanthanurn boride

5.940 *1.000 lanthanum fluoride

Li 0.530 5.900 lithium

LiBr 3.470 1.230 lithium bromide

LiF 2.638 0.778 lithium fluoride

IPN 074-547-P1B

A - 4 PRELIMINARY 5/4/12

Q-pod Operating Manual

Table A-1 Material Table (continued)

Formula Density Z-Ratio Material Name

LiNbO

3

4.700 0.463 lithium niobate

Lu 9.840 *1.000 lutetium

Mg 1.740 1.610 magnesium

MgAl

MgAl

MgF

2O4

2O6

2

3.600 *1.000 magnesium aluminate

8.000 *1.000 spinel

3.180 0.637 magnesium fluoride

MgO 3.580 0.411 magnesium oxide

Mn 7.200 0.377 manganese

MnO 5.390 0.467 manganese oxide

MnS 3.990 0.940 manganese (II) sulfide

Mo 10.200 0.257 molybdenum

Mo

C 9.180 *1.000 molybdenum carbide

2

MoB

MoO

MoS

2

3

2

7.120 *1.000 molybdenum boride

4.700 *1.000 molybdenum trioxdide

4.800 *1.000 molybdenum disulfide

Na 0.970 4.800 sodium

Na

Na

AIF

3

6

5Al3F14

2.900 *1.000 cryolite

2.900 *1.000 chiolite

NaBr 3.200 *1.000 sodium bromide

NaCl 2.170 1.570 sodium chloride

NaCIO

3

2.164 1.565 sodium chlorate

NaF 2.558 1.645 sodium fluoride

NaNO

3

2.270 1.194 sodium nitrate

Nb 8.578 0.492 niobium (columbium)

IPN 074-547-P1B

Nb

Nb

NbB

2O3

2O5

2

7.500 *1.000 niobium trioxide

4.470 *1.000 niobium (V) oxide

6.970 *1.000 niobium boride

NbC 7.820 *1.000 niobium carbide

NbN 8.400 *1.000 niobium nitride

Nd 7.000 *1.000 neodynium

Nd

NdF

2O3

3

7.240 *1.000 neodynium oxide

6.506 *1.000 neodynium fluoride

Ni 8.910 0.331 nickel

PRELIMINARY 5/4/12 A - 5

Q-pod Operating Manual

Table A-1 Material Table (continued)

Formula Density Z-Ratio Material Name

NiCr 8.500 *1.000 nichrome

NiCrFe 8.500 *1.000 inconel

NiFe 8.700 *1.000 permalloy

NiFeMo 8.900 *1.000 supermalloy

NiO 7.450 *1.000 nickel oxide

P

3N5

2.510 *1.000 phosphorus nitride

Pb 11.300 1.130 lead

PbCl

PbF

2

2

5.850 *1.000 lead chloride

8.240 0.661 lead fluoride

PbO 9.530 *1.000 lead oxide

PbS 7.500 0.566 lead sulfide

PbSe 8.100 *1.000 lead selenide

PbSnO

3

8.100 *1.000 lead stannate

PbTe 8.160 0.651 lead telluride

Pd 12.038 0.357 palladium

PdO 8.310 *1.000 palladium oxide

Po 9.400 *1.000 polonium

Pr 6.780 *1.000 praseodymium

Pr

2O3

6.880 *1.000 praseodymium oxide

Pt 21.400 0.245 platinum

PtO

2

10.200 *1.000 platinum oxide

Ra 5.000 *1.000 radium

Rb 1.530 2.540 rubidium

RbI 3.550 *1.000 rubidiurn iodide

Re 21.040 0.150 rhenium

Rh 12.410 0.210 rhodium

Ru 12.362 0.182 ruthenium

S

8

2.070 2.290 sulphur

Sb 6.620 0.768 antimony

Sb

Sb

2O3

2S3

5.200 *1.000 antimony trioxide

4.640 *1.000 antimony trisulfide

Sc 3.000 0.910 scandium

Sc

2O3

3.860 *1.000 scandium oxide

A - 6 PRELIMINARY 5/4/12

IPN 074-547-P1B

Q-pod Operating Manual

Table A-1 Material Table (continued)

Formula Density Z-Ratio Material Name

Se 4.810 0.864 selenium

Si 2.320 0.712 silicon

Si

3N4

3.440 *1.000 silicon nitride

SiC 3.220 *1.000 silicon carbide

SiO 2.130 0.870 silicon (ii) oxide

SiO

2

2.648 1.000 silicon dioxide

Sm 7.540 0.890 samarium

Sm

2O3

7.430 *1.000 samarium oxide

Sn 7.300 0.724 tin

SnO

2

6.950 *1.000 tin oxide

SnS 5.080 *1.000 tin sulfide

SnSe 6.180 *1.000 tin selenide

SnTe 6.440 *1.000 tin telluride

Sr 2.600 *1.000 strontium

SrF

2

4.277 0.727 strontium fluroide

SrO 4.990 0.517 strontium oxide

Ta 16.600 0.262 tantalum

Ta

Ta B

2O5

2

8.200 0.300 tantalum (v) oxide

11.150 *1.000 tantalum boride

TaC 13.900 *1.000 tantalum carbide

TaN 16.300 *1.000 tantalum nitride

Tb 8.270 0.660 terbium

Tc 11.500 *1.000 technetium

Te 6.250 0.900 tellurium

IPN 074-547-P1B

Te O

2

5.990 0.862 tellurium oxide

Th 11.694 0.484 thorium

ThF

ThO

ThOF

4

2

2

6.320 *1.000 thorium.(IV) fluoride

9.860 0.284 thorium dioxide

9.100 *1.000 thorium oxyfluoride

Ti 4.500 0.628 titanium

Ti

TiB

203

2

4.600 *1.000 titanium sesquioxide

4.500 *1.000 titanium boride

TiC 4.930 *1.000 titanium carbide

PRELIMINARY 5/4/12 A - 7

Q-pod Operating Manual

Table A-1 Material Table (continued)

Formula Density Z-Ratio Material Name

TiN 5.430 *1.000 titanium nitride

TiO 4.900 *1.000 titanium oxide

TiO

2

4.260 0.400 titanium (iv) oxide

TI 11.850 1.550 thallium

TIBr 7.560 *1.000 thallium bromide

TICI 7.000 *1.000 thallium chloride

TII 7.090 *1.000 thalliurn iodide (b)

U 19.050 0.238 uranium

U

3O8

U

4O9

UO

2

8.300 *1.000 tri uranium octoxide

10.969 0.348 uranium oxide

10.970 0.286 uranium dioxide

V 5.960 0.530 vanadium

V

VB

2O5

2

3.360 *1.000 vanadium pentoxide

5.100 *1.000 vanadium boride

VC 5.770 *1.000 vanadium carbide

VN 6.130 *1.000 vanadium nitride

VO

2

4.340 *1.000 vanadium dioxide

W 19.300 0.163 tungsten

WB

2

10.770 *1.000 tungsten boride

WC 15.600 0.151 tungsten carbide

WO

WS

WSi

3

2

2

7.160 *1.000 tungsten trioxide

7.500 *1.000 tungsten disulphide

9.400 *1.000 tungsten silicide

Y 4.340 0.835 yttrium

Y

203

5.010 *1.000 yttrium oxide

Yb 6.980 1.130 ytterbium

Yb

2O3

9.170 *1.000 ytterbium oxide

Zn 7.040 0.514 zinc

Zn

ZnF

3Sb2

2

6.300 *1.000 zinc antimonide

4.950 *1.000 zinc fluoride

ZnO 5.610 0.556 zinc oxide

ZnS 4.090 0.775 zinc sulfide

ZnSe 5.260 0.722 zinc selenide

A - 8 PRELIMINARY 5/4/12

IPN 074-547-P1B

Q-pod Operating Manual

Table A-1 Material Table (continued)

Formula Density Z-Ratio Material Name

ZnTe 6.340 0.770 zinc telluride

Zr 6.490 0.600 zirconium

ZrB

2

6.080 *1.000 zirconium boride

ZrC 6.730 0.264 zirconium carbide

ZrN 7.090 *1.000 zirconium nitride

ZrO

2

5.600 *1.000 zirconium oxide

IPN 074-547-P1B

PRELIMINARY 5/4/12 A - 9

Q-pod Operating Manual

This page is intentionally blank.

A - 10 PRELIMINARY 5/4/12

IPN 074-547-P1B