QRC Substrate Technology Characterization Manual.pdf

8/11/2019 QRC Substrate Technology Characterization Manual.pdf

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QRC Substrate Technology

Characterization ManualProduct Version 10.1.2 HF1

July 2011


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20072011 Cadence Design Systems, Inc. All rights reserved.

Cadence Design Systems, Inc. (Cadence), 2655 Seely Ave., San Jose, CA 95134, USA.

Trademarks: Trademarks and service marks of Cadence Design Systems, Inc. contained in this documentare attributed to Cadence with the appropriate symbol. For queries regarding Cadences trademarks,

contact the corporate legal department at the address shown above or call 800.862.4522.

Restricted Permission:This publication is protected by copyright law and international treaties andcontains trade secrets and proprietary information owned by Cadence. Unauthorized reproduction ordistribution of this publication, or any portion of it, may result in civil and criminal penalties. Except as

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print one (1) hard copy of this publication subject to the following conditions:

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customer.

2. The publication may not be modified in any way.

3. Any authorized copy of the publication or portion thereof must include all original copyright,trademark, and other proprietary notices and this permission statement.

4. The information contained in this document cannot be used in the development of like products orsoftware, whether for internal or external use, and shall not be used for the benefit of any other party,

whether or not for consideration.

Disclaimer: Information in this publication is subject to change without notice and does not represent a

commitment on the part of Cadence. Except as may be explicitly set forth in such agreement, Cadence doesnot make, and expressly disclaims, any representations or warranties as to the completeness, accuracy or

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QRC Substrate Technology Characterization Manual

July 2011 3 Product Version 10.1.2 HF1

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9About This Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Platforms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Operating System Versions and Patches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Syntactical Conventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Substrate Characterization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Substrate Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Technology Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Three-Dimensional Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Vertical Mesh Generation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Regions and Cross-Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Design Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Graphical User Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2

Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Starting QRC TCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

QRC TCT Main Window . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

File Selection Dialog Boxes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Exiting QRC TCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

3

How to Use QRC TCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Starting a Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

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Creating a New Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Loading an Existing Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Reverting to a Saved Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Controlling the Screen Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27Zooming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Panning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Controlling Grid Visibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Loading the Doping Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Specifying the Profile Default Directory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Changing the Scale of the Ordinate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Controlling Doping Concentration Profile Visibility . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Controlling Legend Visibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Specifying Regions, Cross-Sections, and Interface Layers . . . . . . . . . . . . . . . . . . . . . . . 31Specifying Region Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Specifying Cross-Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Specifying Interconnect Layer Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Specifying the Gate Layer Names . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Attaching Doping Profiles to Regions/Cross-Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Attaching Doping Profiles to the Default/Default Combination . . . . . . . . . . . . . . . . . . 39

Changing the Doping Profile Display Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Discretizing the Substrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Changing the Discretization Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44Starting a Discretization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Changing a Discretization Manually . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

Changing Region Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

Changing the Junction Parameters of a Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Calculating Junction Capacitance for Two-Dimensional Doping Profiles . . . . . . . . . . 49

Setting Interface Parameters for Interconnects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Setting Interface Parameters for Gates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Setting Interface Parameters for Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Creating the Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52Saving a Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Exporting a Template File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Saving the Technology Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54


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4

Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Session Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57New Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Load Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Save Session . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Revert to Saved . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Export . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Exit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59

Options Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Default Directory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60

Discretization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60View Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Y-Axis Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Zoom . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Grid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Subdivisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Legend . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Edit Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70Regions Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Interface Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77

Subdivision Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80

Discretization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Move . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Add . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Delete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Undo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Redo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82Help Menu . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82

Icon Toolbar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82


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A

Input and Output Files. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Input Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85Session Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85

Template Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Doping Concentration Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Output Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

Technology Description Files . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

B

Preparing Doping Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89Regions and Cross-Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Cross-Sections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90

Information Provided by the Process Engineer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Doping Profiles Required . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

CMOS Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

BiCMOS Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Information Relevant to QRC AoT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Beginning of the Doping Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

Substrate Depth Reference . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

End of the Doping Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97

Doping Profile File Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

Electrons and Holes Concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

Net Carrier Concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

Acceptor and Donor Concentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Resistivity Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99

Recommendations for Creating Doping Profiles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Substrate Depths for N-P and P-N Transitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101

Doping Profile Representations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

Junction Representations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102

Doping Profile Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

Start of the Doping Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

Transition Region . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104


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Final Values . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107


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Preface

About This Book

This manual describes how to use QRC Technology Characterization Tool (TCT) tocharacterize your technology and generate a technology description file to use with QRC AoT.

This manual covers the following topics:

Chapter 1, Introduction,describes QRC TCTs function, design flow, inputs, outputs,and graphical user interface. It also provides some background information on substratecharacterization, substrate modeling, and the technology description that QRC TCTgenerates.

Chapter 2, Getting Started,describes how to start and exit QRC TCT, how to use thefeatures of its main window, and how to use its file selection dialog boxes.

Chapter 3, How to Use QRC TCT,explains how to perform QRC TCTs main functions.

Chapter 4, Commands,describes the commands that are available in QRC TCTsgraphical user interface menus.

Appendix A, Input and Output Files,describes QRC TCTs input and output files.

Glossarydefines the terms and concepts that you should understand to use QRC TCTeffectively.

Platforms

This product is supported as a 32-bit executable on all currently supported platforms. It is notavailable as a 64-bit executable. Refer to the Whats New for the specific release you areusing for details of the supported platforms for that release.

Operating System Versions and Patches

For information about supported operating system versions and current patches, see therelease notes for the current release.
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QRC Substrate Technology Characterization ManualPreface


Syntactical Conventions

This document uses the following syntactical conventions:

Commands and parameters used on the command line are given in Courierfont:

command_name

Menu commands and the fields in dialog boxes in the graphical user interface are givenin Helveticaitalicfont:

File Save

An en dash () separates the menu name and the command name.

Variables for which you are to substitute a value are given in Courieritalicfont:

filename, cellname, layer_name

File names are given in Courierfont:

library.lib

Angle brackets enclose optional parameters:

Vertical bars (|) in commands indicate choices.

Square brackets indicate that you must select one of the choices:

[a|b|c]

Square brackets followed by a plus sign mean that you can choose more than one of thechoices, but you must select at least one:

[a|b|c]+

Use white space (tabs or spaces) to separate a command and its arguments.


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1

Introduction

This chapter describes QRC TCTs function, design flow, inputs, outputs, and graphical userinterface. It also provides some background information on substrate characterization,substrate modeling, and the technology description that QRC TCT generates.

Function

QRC TCT, the technology characterization tool, prepares the technology description thatQRC AoT uses to generate the substrate macromodel.

QRC TCT performs the following functions:

Defines the available doping concentration profiles, drawn layers, and interfacelayers

Loads the doping profiles

Defines regions and cross-sectionsto identify available combinations of drawn layers

Uses doping profiles to determine the depths of the vertical discretizationof thesubstrate

Defines interface connection parameters for each interface layer to differentregion/cross-section combinations

Defines interface connection types between the interface layers and the differentregion/cross-section combinations

Computes vertical and horizontal impedance values for each subdivision of each dopingprofile

Computes capacitance parameters for the p-n junctions between wells and the substrate

Saves the technology file in an encrypted format
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QRC Substrate Technology Characterization ManualIntroduction


Substrate Characterization

Substrate characteristics throughout silicon depend directly on carrier concentration. In aplanar technology, the concentration of electrons and holes is controlled by the fabricationprocess and set of mask layers:

Drawn layers, which are used to create the circuit layout, define a set of masks used inthe circuit fabrication process. Figure 1-1 on page 12shows the top view of the layout forNMOS and PMOS transistors in a CMOStechnology, with their corresponding drawnlayer.

Figure 1-1 NMOS and PMOS Layout

Profile layersare masks that directly influence the lateral variation of the carrierconcentration across the substrate.

Interface layers are mask layers above the substrate surface that can couple to thesubstrate surface resistively or capacitively. Normally, interface layers are interconnectlayers. The resistance and capacitance values between the substrate and the interfacelayer are known as the layers electrical connection parameters.

Figure 1-2 on page 13shows a cross-section of the layout through the a-a axis for a p-substrate process, illustrating the different mask layers and identifying the interface andprofile layers.

aa

NMOS PMOS metal

contact

poly

ndiff

pdiff

pwell

nwell
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Figure 1-2 Cross-Section of a Standard CMOS Process

Each combination of drawn layers produces a particular vertical carrier concentrationvariation known as the vertical doping profile. For any specific process, substratecharacteristics are fully described by a number of these profiles. Refer to Appendix B,Preparing Doping Profiles,for more information on defining these profiles.

The following process steps are those most likely to influence substrate characteristics:

Well implantation and diffusion

Field and channel stop implants

n+ and p+ implants used to contact the substrate

QRC TCT defines available profile layers, interface layers, layer combinations, and theirassociated vertical doping profiles. It also divides the substrate into vertical subdivisions

computed from vertical doping profiles. QRC uses this information and the layout of the circuitunder analysis to build an RC network that models the substrate. You can connect this RCnetwork to the ideal circuit netlist, as Figure 1-3 on page 14illustrates.

Doping

layers

Interfacelayers
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Figure 1-3 QRC AoT Substrate Model

Substrate Model

To generate a macromodel of the substrate, theQRC AoT extractor uses a simplifiedrepresentation of the layout with a specific technology description. This flow is pictured inFigure 1-4 on page 14.

Figure 1-4 QRC AoT Simplified Flow

The layout representation is called the substrate abstract view, which includes informationrelated to the generation of a surface mesh.

Layout Abstract view Technology

Partitioning

Model construction

Mesh
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Technology Description

The doping profiles for each combination of drawn layers are constant for a particularprocess. The technology description characterizes the substrate for each doping profile anddefines the vertical mesh of the initial substrate model, as illustrated in Figure 1-5 on page 15.

Figure 1-5 Three-Dimensional Substrate Model

QRC TCT saves the description in a technology descriptionfile, which includes informationsuch as mask layer combinations, vertical- and horizontal-specific resistances for eachvertical subdivision of the doping profiles, interface layers, interface parameters, andinterface connections. QRC TCT loads all these technology parameters to define a substratemodel and to link the access ports to external nodes.

Three-Dimensional Modeling

QRC TCTgenerates a three-dimensional mesh comprising a set of cells modeled as shownin Figure 1-6 on page 16.
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Figure 1-6 Electrical Model for a Single Cell

For two such cells next to each other, the two impedances in series are joined by connection

nodes. This arrangement simplifies to a single impedance, eliminating the connection nodes.As a result, the complete three-dimensional mesh model is a set of main nodes linked byimpedances.

Impedance is determined by the following attributes:

The doping profile

Vertical subdivision within the profile

Vertical Mesh Generation

The process of generating a discrete mesh from the continuous vertical doping profilesinvolves a loss of accuracy. On one hand, the goal of vertical mesh generation is to preserveaccuracy by minimizing the total deviation from the vertical concentration profiles. On theother hand, the mesh must be coarse enough to ensure acceptable performance.

QRC TCT produces vertical division intervals by placing boundaries at coordinates at whichthe profiles greatly change, such as junctions or n+ or p+ implant depth. More subdivisionsresult in a more accurate model but also increase processing time for model extraction.

After mesh generation, QRC TCT computes the specific substrate resistance within eachinterval by using a piecewise constant approximation, explained in Figure 1-7 on page 17.

Connection node

Main node

Impedance
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Figure 1-7 Vertical and Horizontal Impedance Definition

Carrier concentration variation is more pronounced near the substrate surface. Beyond acritical depth, the net carrier doping concentration can safely be assumed to be constant.

Regions and Cross-Sections

For better ease of use, QRC TCT uses regions and cross-sections.

A region is identified by vertical p-n junctions with the same vertical position. All layout areashaving the same number of transitions at the same vertical position can be characterized asone region. Here are some examples:

A default region, which is always present and does not contain any p-n junction

A well region, such as an nwell in a p-doped substrate, which has one p-n junctionbetween the nwell and the substrate

A triple well region, which may contain two p-n junctions, such as a pwell placed in ann pocket on top of the p substrate

A deep well region, which is another nwell in a p-doped substrate but resides at a vertical

depth different from the previous well region

A cross-section is a name for a generic function shared by several regions. It defines theinterface between the substrate and devices and interconnects. Examples are the following.

Default, which is always present and should be chosen to be the default cross-section

Resistance

Substrate

Subdivision

Wafer surfaceDoping profile

Backside z (depth)
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Contact, which defines a cross-section for a substrate contact, a well contact, a triple wellcontact, and so forth

Source/drain, which defines all source and drain areas in all possible regions

Combinations of regions and cross-sections are attached to resistivity profiles to enable aone-to-one mapping.

Refer to the QRC Substrate Technology Characterization Tutorialfor illustratedexamples.

Design Flow

The QRC TCT design flow is illustrated in Figure 1-8.

Figure 1-8 QRC TCT Program Flow

Technology file

Generate technology file

Discretize profiles

Load dopingprofiles Assign regions

and cross-

sections

Enter interfaceparameters

Enter interface

connection types

Enter profile layers,interface layers
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Inputs

QRC TCT accepts three inputs:

A template file, which contains all the important values that define regions, cross-sections, and interface layers. Cadence provides the template files. Some examplesreside in $ASSURAHOME/share/sna/TCTtemplates. They are prepared for the mostcommon technologies and can be used as a basis for your technology. Template files areoptional. See Appendix A, Template Files,.

Note: The TCT Template files are available in the Assura installation. They are notincluded with the EXT7.1 release.

Doping concentration profiles, which contain information about electron and holeconcentration, net carrier concentration, acceptor and donator concentration, andresistivity. You can also submit doping profiles for junction capacitance calculation.These profiles must be obtained from the fabrication process department at your site.These files are required. See Appendix B, Preparing Doping Profiles,for moreinformation.

Session files, which contain the values of all variables that you set in QRC TCT to allowyou to save the configuration of the tool and any work. QRC TCT reads and writes theseoptional session files. See Appendix A, Session Files,.

Outputs

QRC TCT creates the following outputs:

A technology description file in an encrypted format. See Appendix A, TechnologyDescription Files,for more information.

Session files, which contain the values of all variables that you set in QRC TCT.

A template file, which contains all the important values that define regions, cross-sections, and interface layers.

Graphical User Interface

QRC TCTs graphical user interface enables you to set parameters while preparing atechnology description file. It gives you a maximum of control on all calculated or usedparameters. It controls the automatically generated subdivisions but allows you to add, move,or delete some of those manually.
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The graphical user interface displays doping concentration profiles in several scales.

After discretization, QRC TCT displays each subdivision as well as all the doping profiles, as

shown in Figure 2-1 on page 22.
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2

Getting Started

This chapter describes how to start and exit QRC TCT, how to use the features of its mainwindow, and how to use its file selection dialog boxes.

Starting QRC TCTYou can start QRC TCT from the UNIX command line prompt as follows:

snatct [&]

Note: The optional & starts the program in background mode.

The main window now appears.

QRC TCT Main Window

QRC TCTs main window, shown in Figure 2-1 on page 22, is designed to show the dopingconcentration profiles as well as other important parameters.
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Figure 2-1 QRC TCT Main Window

The QRC TCT main window is resizable. It is divided into the following areas:

The title banner shows the current session name and enables you to move the window.System buttons minimize (iconize), maximize, or restore the window size.

The menu bar contains a set of pulldown menus.

The icon bar displays shortcut icons that execute the most important commands in themenu bar. See Icon Toolbar on page 82for a description of each individual icon.

The display panel displays doping profiles and subdivisions. You can view the results ofthe discretization and manually add or remove subdivisions.

The scrollable log panel contains a log of the activities, warnings, and error messages.

Title banner

Menu bar

Icon bar

Display panel

Discretization

Log panel

Status bar


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The status bar provides contextual information, such as the currently activatedcommand.

File Selection Dialog Boxes

Many QRC TCT commands activate a file selection dialog box similar to that shown inFigure 2-2 on page 23.

Figure 2-2 File Selection Dialog Box

This dialog box contains the following fields:

Filter

Specifies a file path and matching pattern from which the contents of the Directoriesand Filesfields are determined. For example, if the last parameter in the path name is*.cmd, only files ending with .cmd are displayed in the Filesfield. If the last parameter inthe path name is an asterisk (*), all files in the specified path are listed.

Directories

Lists the subdirectories of the path that you selected in the Filterfield.

Files
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Lists the files that match the pattern specified in the Filterfield.

Selection

Displays the status of your selection process.

To use this dialog box, follow these steps:

1. To move to a directory, enter the path name of the directory in the Filterfield. To list thefiles that reside in that directory, specify /*after the path name.

2. To select a subdirectory, double-click on the name of the subdirectory in the Directoriesfield.

The Filterfield now shows the new path. The Directoriesand Filesfields are alsoupdated to reflect the contents of the new path.

3. To select a file, double-click on the name of the file in the Filesfield. Alternatively, youcan single-click to update the Selectionbox.

4. When you are finished with the selection process, click on OKto select what is shown inthe Selectionbox.

Exiting QRC TCT

To exit QRC TCT, do the following.

1. Select Session Exit.

A confirmation dialog box appears, as shown in Figure 2-3 on page 24.

Figure 2-3 Exit QRC TCT Confirmation Box

2. Click on OKto exit the tool.
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3

How to Use QRC TCT

This chapter explains how to perform QRC TCTs major functions.

Starting a Session

This section shows you how to create a new session or load an existing session. It also tellsyou how to revert to a previously saved session.

Creating a New Session

To clear the current database and start a new session, select Session New Session, orclick on the icon on the icon bar. Alternatively, you can press Ctrl Nwhen the QRC TCTmain window is active. All previous operations are lost, and the QRC TCT environment isreset. If you want to keep your current session, save it beforehand.

If the $ASSURAHOME/share/sna/TCTtemplatesdirectory contains template files, thetemplate file selection window appears, as shown in Figure 3-1 on page 26. You can now loadone of the prepared sessions and adapt it to your needs.

If no template files are available, only the database is cleared, and all variables are reset.
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Figure 3-1 Template File Selection Window

Loading an Existing Session

To load an existing QRC TCT session, follow this procedure:

1. Select Session Load Session, or click on the icon on the icon bar. Alternatively,you can press Ctrl Lwhen the QRC TCT main window is active.

A file selection dialog box opens, as shown in Figure 3-2 on page 27.
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Figure 3-2 Select a Session File Dialog Box

2. Select an appropriate file, following the instructions in File Selection Dialog Boxes onpage 23.

3. Click on OK.

Reverting to a Saved Session

If you want to revert to a session that has already been savedfor example, to undo all thechanges you made in the meantimechoose Session Revert to Saved. This commandrestarts the session from the point that you previously saved or loaded it.

Alternatively, you can press CtrlRwhen the QRC TCT main window is active.

Controlling the Screen DisplayBefore you begin creating the technology file with QRC TCT, it is helpful to understand howto zoom and pan the views that you see on-screen.
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Zooming

Zoomingis the process of magnifying or shrinking the view of a selected area of the chip. To

zoom, you can use the commands on the Zoom submenu activated by the View Zoomcommand or the corresponding buttons on the icon bar.

To zoom in on, or enlarge, a selected area, select View Zoom. Press and hold the leftmouse button around the area to enlarge. When you release the button, the view isreplaced by the enlarged view. You can also use the icon.

To zoom in by a factor of 2, select View Zoom Zoom In. You can also use the ShiftZkeyboard command or the icon.

To zoom out, or shrink the view, by a factor of 2, select View Zoom Zoom Out. Youcan also use the Ctrl zkeyboard command or the icon.

Other zoom commands, such as zooming along the X axis, are also available. See Zoomon page 65for detailed information on these commands.

Panning

Panning is the process of obtaining a panoramic view of the design by selecting one pointas the center of the view without changing the scale of the design. You can pan the view tothe left, right, up, or down by half a screen.

To pan left, select View Zoom Pan Left.You can also use the left arrow key.

To pan right, select View Zoom Pan Right.

You can also use the right arrow key.

To pan up, select View Zoom Pan Up.

You can also use the up arrow key.

To pan down, select View Zoom Pan Down.

You can also use the down arrow key.

Controlling Grid Visibility

To display or hide the grid, select View Grid. Alternatively, you can select the buttonon the icon bar.
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Loading the Doping Profiles

The first step in preparing the technology file is to load the doping concentration profiles thatwill be attached to the combination of regions and cross-sections.

Specifying the Profile Default Directory

To specify the directory where QRC TCT searches for the doping profiles, follow these steps:

1. Choose Options Default Directory.

The Select a Default Directory dialog box appears, as shown in Figure 3-3 on page 29,so you can specify the directory.

Figure 3-3 Select a Default Directory Dialog Box

2. Fill in the fields of the dialog box according to the instructions given in File SelectionDialog Boxes on page 23.

3. Click on OK.

Changing the Scale of the Ordinate

You can change the scale of the doping concentration profiles.

To display the concentration profiles of electrons and holes on a linear scale, select View Y-axis Scale Electrons And Holes (lin).
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To display the concentration profiles of electrons and holes on a logarithmic scale, selectView Y-axis Scale Electrons And Holes (log).

To display the net concentration profiles on a linear scale, select View Y-axis Scale Net Carriers (lin). Use a plus (+) sign to indicate that electrons are the majoritycarriers; use a minus (-) sign to indicate that holes are the majority carriers.

To display the net concentration profiles on a logarithmic scale, select View Y-axisScale Net Carriers (log). Use a plus (+) sign to indicate that electrons are themajority carriers; use a minus (-) sign to indicate that holes are the majority carriers.

To display the resistivity profiles on a linear scale, select View Y-axis Scale Resistivity (lin).

To display the resistivity profiles on a logarithmic scale, select View Y-axis Scale

Resistivity (log).

Alternatively, use the following two icons to change the scale:

Increases the scale and unit of the doping concentration profiles.

Decreases the scale and unit of the doping concentration profiles.

Controlling Doping Concentration Profile Visibility

By selecting View Regions, you can display or hide doping concentration profiles in

different ways. You can view all of them, you can view them by combinations of regions andcross-sections, or you can view none of them.

Controlling Legend Visibility

You can display the legend for the doping concentration profiles either by combinations ofregion and cross-section or by profile.

1. Click on View Legendto display or hide the legend. Alternatively, you can click on theicon on the icon bar.

The Legend dialog box appears, as shown in Figure 3-4 on page 31.
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Figure 3-4 Legend Dialog Box

2. Select Region/Cross-sectionor Profile.

Specifying Regions, Cross-Sections, and Interface

Layers

The next step in generating a technology description is to specify the regions, cross-sections,and interface layers of the design.

Specifying Region Names

To specify region names, follow these steps:

1. Select Edit Setup Region Names, or click on the icon.

The Define Regions dialog box appears, as shown in Figure 3-5 on page 32.
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Figure 3-5 Define Regions Dialog Box

2. Use the Add, Modify, and Removebuttons to change the list of regions.

To add a region to the list, do the following:

a. Click on Add.

The Create New Region dialog box appears, as shown in Figure 3-6 on page 32, soyou can specify the name of the region to add.

Figure 3-6 Create New Region Dialog Box

b. Type in the name of the region.

c. Click on OK.

To modify the name of a region in the list, do the following:

a. Highlight the name of the region that you want to change.

b. Click on Modify.

c. The Add Region Name dialog box appears, as shown in Figure 3-7 on page 33.
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Figure 3-7 Add Region Name Dialog Box

d. Backspace over the existing name and type the name of the region that you wish toadd.

e. Click on OK.

To remove the name of a region from the list, do the following:

a. Highlight the name of the region that you want to remove.

b. Click on Remove.

3. Click on Donein the Define Regions dialog box.

You can use the Revertbutton to revert to the last saved list or the Cancelbutton toclose the window without saving.

Specifying Cross-Sections

You can use a cross-section in several regions. It has two purposes:

It serves as a unique identification of the doping concentration profile to be used underan access port with the unique combination of region name and cross-section name.

It specifies how interconnects are connected to the substrate model: resistively,capacitively, or not at all.

Refer to Chapter 1, Introduction,for more information about regions and cross-sections.

To specify cross-sections, do the following:

1. Select Edit Setup Cross-Sections, or select the icon.

The Cross-Sections dialog box appears, as shown in Figure 3-8 on page 34.
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Figure 3-8 Cross-Sections Dialog Box

2. Use the Add, Modify, and Removebuttons to modify the list of cross-sections and theirproperties.

To add a cross-section to the list, do the following:

a. Click on Add.

The Add Cross-Section dialog box appears, as shown in Figure 3-9 on page 34, soyou can specify the name of the cross-section to add.

Figure 3-9 Add Cross-Section Dialog Box

b. Type in the name of the cross-section.

c. In the Interface Connectionsfield, select Resistiveor Capacitive.

d. Click on OK.

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a. Highlight the name of the cross-section that you want to change.

b. Click on Modify.

c. The Modify Cross-Section dialog box appears, as shown in Figure 3-10 on page 35.

Figure 3-10 Modify Cross-Section Dialog Box

d. Backspace over the existing name and type the name of the cross-section that youwish to add.

e. In the Interface Connectionsfield, select Resistiveor Capacitive.

f. Click on OK.

To remove the name of a cross-section from the list, do the following:

a. Highlight the name of the cross-section that you want to remove.

b. Click on Remove.

3. Click on Donein the Cross-Section dialog box.

4. Define the interface connections by selecting one of the following options.

Nothing selected

If you neither select Resistivenor Capacitive, a connection between an access

port and the substrate model will not be allowed for this type of cross-section.

Resistive

Enables a resistive connection between an access port and the substrate model.

Capacitive
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Enables a capacitive connection between an access port and the substrate model.Choose the type of capacitive connection appropriate for this cross-section:

interConnectOnFieldSelects the interconnects that connect to the substrate but that do not resideabove a region where a device is located.

interConnectOnActive

Selects the interconnects that connect to the substrate and that reside above aregion where a device is located.

gate

Selects the interconnects that connect to the substrate through the gate of MOS

transistors.

Specifying Interconnect Layer Names

Now you will specify the layer names of the interconnects in your design:

1. Select Edit Setup Interface Interconnects, or click on the icon.

The Interconnects dialog box opens, as shown in Figure 3-11 on page 36.

Figure 3-11 Interconnects Dialog Box

2. Use the Add, Modify, and Removebuttons to change the list of interconnect layers.

To add a layer name to the list, do the following:
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a. Click on Add.

The Create New Interconnect dialog box appears, as shown in Figure 3-12 on

page 37, so you can specify the name of the layer to add.

Figure 3-12 Create New Interconnect Dialog Box

b. Type in the name of the layer.

c. Click on OK.

To modify the name of a layer in the list, do the following:

a. Highlight the name of the layer that you want to change.

b. Click on Modify.

c. The Add Interconnect Name dialog box appears, as shown in Figure 3-13 onpage 37.

Figure 3-13 Add Interconnect Name Dialog Box

d. Backspace over the existing name and type the name of the layer that you wish toadd.

e. Click on OK.
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To remove the name of a layer from the list, do the following:

a. Highlight the name of the layer that you want to remove.

b. Click on Remove.

3. Click on Doneto effect the changes.

Specifying the Gate Layer Names

Finally, specify the layer names of the interconnects in your design serving as the gate layer:

1. Select Edit Setup Interface Gates, or click on the icon.

The Gates dialog box appears, as shown in Figure 3-14 on page 38.

Figure 3-14 Gates Dialog Box

2. Use Add, Modify, and Removebuttons to change the list of interconnect layers thatconnect to gates of MOS transistors. Follow the procedure in step 2in SpecifyingInterconnect Layer Names on page 36.

3. Click on Donein the Gates dialog box to implement the changes.

Attaching Doping Profiles to Regions/Cross-Sections

The next step is to attach the doping concentration profiles given in ASCII files to thecombinations of regions and cross-sections. If you started without using one of the templates,the first combination of region and cross-section is always composed of the default region andthe default cross-section.
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Attaching Doping Profiles to the Default/Default Combination

First, attach doping concentration profiles to the default combination of regions and cross-

sections.

1. Select Edit Region Parameters, or click on the icon.

The Regions Parameters dialog box opens, as shown in Figure 3-15 on page 39.

Figure 3-15 Regions Parameters Dialog Box

2. In the Region Namefield, choose the name of the defaultregion.

3. Click on Cross-Sections.

The Select a Doping Profile dialog box, shown in Figure 3-16 on page 39, appears soyou can select the appropriate doping concentration profile.

Figure 3-16 Select a Doping Profile Dialog Box


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4. Select a doping profile, using the instructions given in File Selection Dialog Boxes onpage 23.

5. Click on OKin the Select a Doping Profile dialog box.The doping profile attachment window now appears, as shown in Figure 3-17 onpage 40.

Figure 3-17 Doping Profile Attachment Window

6. You can change the parameters in this window by following the instructions in Changingthe Doping Profile Display Parameters on page 42.

7. Click on OKin the doping profile attachment window.

Now the cross-section selection dialog box appears, as shown in Figure 3-18 onpage 41.
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Figure 3-18 Cross-Section Selection Dialog Box

In the title of the cross-section selection dialog box, the name of the actual region isdisplayed; for example, in Figure 3-18 on page 41the default region is shown. The dialogbox contains two sections: the Selected Cross-Sectionsbox contains the alreadyselected cross-sections, and the Available Cross-Sectionsbox contains the availablecross-sections.

8. Attach other profiles to other cross-sections for the default region:

a. In the cross-section selection dialog box, select an available cross-section in the listat the right, and click on the left arrow.

The Select a Doping Profile dialog box shown in Figure 3-16 on page 39opens.

b. Select a profile, and click on OK.

The Select a Doping Profile dialog box now closes, and the doping profileattachment window shown in Figure 3-17 on page 40opens.

c. You can change the parameters in this window by following the instructions given inChanging the Doping Profile Display Parameters on page 42and clicking on OKin the doping profile attachment window.

The cross-section selection dialog box opens.

9. Repeat step 8until all necessary cross-sections for the default region are attached todoping profiles.

10. In the cross-section selection dialog box, click on Done.

The cross-section selection dialog box now closes but the Regions Parameters dialogbox remains open.
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11. Attach profiles to other regions:

a. Choose a second region, for example, nwell.

b. Click on Cross-Section.

The Select a Doping Profile dialog box appears.

c. Select a profile, and click on OK.

The Select a Doping Profile dialog box closes, and the doping profile attachmentwindow opens.

d. You can change the parameters in this window by following the instructions given inChanging the Doping Profile Display Parameters on page 42and clicking on OKin the doping profile attachment window.

The doping profile attachment window closes. The cross-section selection dialogbox opens.

12. Repeat step 11until all necessary cross-sections for the second region are attached todoping profiles.

13. In the cross-section selection dialog box, click on Done.

The cross-section selection dialog box now closes. The Regions Parameters dialog boxremains open.

14. Repeat steps step 11through step 13until all necessary region/cross-sectioncombinations are attached to doping profiles.

15. In the Regions Parameters dialog box, click on Done.

Changing the Doping Profile Display Parameters

Figure 3-17 on page 40shows the doping profile attachment window. At the top, this windowcontains the path to and the name of the file with the doping concentration. The displayedgraphs vary according to the format of this file; for example, in Figure 3-17 on page 40thedoping concentration profile for the default region and the contact cross-section is given in

electrons and holes.

1. You can change the way of displaying these profiles by clicking on the following fields onthe doping profile attachment window:

Set Color

Opens a color definition window, enabling you to change the default color.


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Line Style

Sets the line style. You can choose from solid, dot, long dashed, short dashed, or

dot dashed. Horizontal Axis

Displays the maximum and minimum value of the depth for this doping profile.

Default

Re-enters the default values for the axis.

Redraw

Updates the screen.

Vertical Axis

Displays the profiles in linear scale or in logarithmic scale.

2. Click on OK.

Discretizing the Substrate

You can specify how the substrate will be vertically discretized. The discretization dependson the following:

The doping concentration profiles and their slopes

The parameters set in the Options menu

The critical depth and the backside depthare important values. From surface to criticaldepth, profiles exhibit much variation in carrier concentration. QRC TCT discretizes thisregion in small subdivisions to achieve an accurate model. From critical depth to the backsideof the substrate, the subdivisions are coarser because the carrier concentration is assumedto be constant in this region. QRC TCT takes the last value found in each doping profile.Figure 3-19 on page 44illustrates critical depth and backside depth.
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Figure 3-19 Definition of Critical Depth and Backside Depth

Changing the Discretization Parameters

QRC TCT automatically calculates the critical depth, but you can change it manually in thedialog box activated by the Options Discretizationcommand. You can also use thiscommand to enter values for the backside depth.

1. Select Options Discretization.

The Discretization dialog box appears, as shown in Figure 3-20 on page 45.

Min depth

Critical

depth

Backside

depth

Doping profiles

0

z z
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Figure 3-20 Discretization Dialog Box

See Discretization on page 60for an explanation of these fields.

2. Click on Doneto set the discretization parameters.

If you have already performed a discretization or if you have changed a session containingdiscretizations, QRC TCT issues a warning message to inform you that it is overwriting thediscretization parameters and therefore the discretization.


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Starting a Discretization

To start a discretization, select Subdivision Discretization.

If all parameters are set correctly and if the doping profiles pass several verifications, theproposed discretization is displayed in QRC TCTs display panel.

Changing a Discretization Manually

You may want to change the discretization manually. Use the commands on the Subdivisionmenu.

Remember that you must weigh speed versus accuracy when deciding on the number of

subdivisions. A high number of subdivisions results in a higher level of accuracy, but QRCTCT takes longer to extract the substrate model. A low number of subdivisions results in alower level of accuracy but increases the extraction speed.

Controlling Subdivision Visibility

You can display or hide the subdivisions by selecting View Subdivisions. You can onlydisplay them if you have previously performed a discretization. Alternatively, you can click onthe icon on the icon bar.

Moving a Subdivision

To move a subdivision, follow these steps:

1. Select Subdivision Move. Alternatively, you can select Ctrl M, or click on theicon.

2. Place the cursor on the dedicated subdivision. The cursor style changes.

3. Left-click on the subdivision, and drag it to the left or to the right. A subdivision can onlybe moved between its neighbor subdivisions.

4. Exit move mode by clicking on Subdivision Move.

Adding a Subdivision

To add a subdivision, follow these steps:

1. Select Subdivision Add. Alternatively, you can select Ctrl A, or click on theicon.


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2. Type in the X coordinate of the new subdivision.

3. Click on OK.

The subdivision is added in QRC TCTs display panel.

Note: In cases where sufficient number of subdivisions have not been selected near the topsurface, then QRC TCT asks the user whether it should automatically insert additional sub-divisions. This feature is designed to help ensure sufficient accuracy near the critical surfaceinterface.

Deleting a Subdivision

To delete a subdivision, follow these steps:

1. Select Subdivision Delete. Alternatively, you can select Ctrl D, or click on theicon.

2. Place the cursor on the dedicated subdivision.

The cursor style changes.

3. Left-click on the subdivision to be deleted.

4. Exit delete mode by clicking on Subdivision Delete.

Some of the discretizations cannot be removed because they are necessary to maintain

accuracy.

Undoing and Redoing Changes to a Subdivision

To reverse the last changes to a subdivision, select Subdivision Undo. Alternatively, youcan select u, or click on the icon.

To re-execute the last changes to a subdivision, select Subdivision Redo. Alternatively,you can select r, or click on the icon.

Changing Region Parameters

You can change the region parameters.


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Changing the Junction Parameters of a Region

If a region contains p-n junctions, for example, between the n-doped well and the p-doped

substrate, QRC adds capacitors to model the junction capacitance between both sides of thep-n junction. To change the junction parameters for a region, follow these steps. To calculatethe junction capacitance for two-dimensional doping profiles, see the next section.

1. To change a regions junction parameters, click on Edit Regions Parameters, or clickon the icon.

The Regions Parameters dialog box appears, as shown in Figure 3-21 on page 48.

Figure 3-21 Regions Parameters Dialog Box

2. In the Region Namelist, select a region containing p-n junctions.

3. Click on Junction Parameters.

The Junction Parameters dialog box appears, as shown in Figure 3-22. This exampleshows the Junction Parameters dialog box for an nwell with one p-n junction.

Figure 3-22 Junction Parameters Dialog Box

4. You can determine the area and perimeter capacitance values used for these capacitorsin different ways:

Calculated


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Automatically determines the capacitance values.

User-Defined

Enables you to define the perimeter and area capacitance values. If your regioncontains several p-n junctions, several fields appear for you to enter the perimeterand area values.

2-D Geometry

Accepts a file that is generated from a process simulator and that contains two-dimensional doping concentration information. QRC accepts MEDICI, SUPREM,and ISEfile syntax.

5. Click on OKto change the parameters.

Calculating Junction Capacitance for Two-Dimensional Doping Profiles

The capacitance values required to model junction capacitors for the p-n junctions in thedifferent regions can be calculated by QRC TCT, user-defined with fixed values, or derivedfrom two-dimensional geometry. If you want to use two-dimensional geometry, Cadencerecommends that you read this section.

1. Click on Edit Regions Parameters.

The Regions Parameters dialog box appears, as shown in Figure 3-21 on page 48.

2. Select a region with p-n junctions in the Regions Parameters dialog box.

3. Click on Junction Parameters.

The Junction Parameters dialog box appears, as shown in Figure 3-22 on page 48.

4. Choose 2-D Geometry, and click on OK.

You are asked to provide a file with two-dimensional geometry and doping profileinformation. You can generate this file with process simulators. QRC TCT supportsSUPREM and MEDICI.

5. Define a cut through the regions under consideration containing the p-n junctions. Thiscut must be two-dimensional. For more details on this issue, contact Cadence CustomerSupport.

Setting Interface Parameters for Interconnects

Follow this procedure to set the interface parameters for the interconnects:
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1. Select Edit Interface Parameters Interconnect, or click on the icon.

The Interconnect Parameters dialog box appears, as shown in Figure 3-23 on page 50.

Figure 3-23 Interconnect Parameters Dialog Box

2. Select one layer after the other from the Interconnectfield, and set the appropriatevalues for resistance [ohm*m2] and capacitance for area [fF/m2] and perimeter [fF/m].

3. Click on OK.

Here are some examples from a simple CMOS technology:

A metal_2 layer is never connected to contacts, so the resistance values are -1. Incontrast, there may be a capacitive connection between a metal_2 layer and thesubstrate, so at least the area capacitance values should be entered. For additionalaccuracy, you can use the perimeter capacitance values.

A polysilicon layer is never connected to contacts, so the resistance values are -1. Incontrast, there may be a capacitive connection between a polysilicon layer and thesubstrate, so at least the area capacitance values should be entered. For additionalaccuracy, you can use the perimeter capacitance values. In contrast to the metal_2 layer,the area value for a capacitive interface on field oxide is higher, since the distancebetween the polysilicon layer and the substrate is smaller than the distance between themetal_2 layer and the substrate.
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A metal_1 layer is the interface layer for the contacts. A 10-ohm*m2resistance value isgiven to model the resistivity of the contact metallization. The values may be different forn-contacts and p-contacts. There may also be a capacitive connection between a

metal_1 layer and the substrate, so at least the area capacitance values should beentered. For additional accuracy, you can use the perimeter capacitance values.

Setting Interface Parameters for Gates

To set the interface parameters for gates, perform these steps:

1. Select Edit Interface Parameters Gate, or click on .

The Gate Parameters dialog box appears, as shown in Figure 3-24.

Figure 3-24 Gate Parameters Dialog Box

2. Select one layer after the other from the Gatesfield, and set appropriate values for

capacitance for area [fF/m2

] and perimeter [fF/m].3. Click on OK.

Setting Interface Parameters for Devices

To set the interface parameters for devices, do the following:
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1. Select Edit Interface Parameters Device, or click on the icon.

The Device Parameters dialog box appears, as shown in Figure 3-25 on page 52.

Figure 3-25 Device Parameters Dialog Box

By default, all devices are connected resistively to the substrate. You can change to acapacitive connection by setting capacitance values for area [fF/m2] for the differentcross-sections available.

2. Select one region after the other from the Regionsfield, and set appropriate values forthe different cross-sections.

3. Click on OK.

Creating the Output

This section describes how to save a session, a template, and a technology description.

Saving a Session

Save your current QRC TCT session by following these steps:

1. Select Session Save Session, or click on the icon on the icon bar. Alternatively,you can press Ctrl Swhen the QRC TCT main window is active.

The file selection dialog box shown in Figure 3-26 on page 53appears so you can enterthe name of the session to save.


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Figure 3-26 Save Session File Selection Dialog Box

The current database, including profiles path and settings, is stored in a file. You canchoose any file name and suffix, but since the default filters expect a .tct suffix, it isrecommended that you use a .tct suffix.


3. Click on OK.

Before saving a session, QRC TCT performs several tests. It may issue warningmessages, asking you to add or change something before saving. If you want to save thesetup in a template file, use the Session Exportcommand, as described in theExporting a Template File on page 53.

When you save a session, QRC TCT preserves all current information, including the paths tothe doping profiles, interface parameters, options, and environment settings.

Exporting a Template File

A template file contains only the basic information about a session that can be applied tosimilar sessions. For example, in the $ASSURAHOME/share/sna/TCTtemplatesdirectory, you will find two templates, one for a CMOS technology and the other for BiCMOStechnology. They contain the predefined regions, cross-sections, and interconnect layers thatyou can use as a starting point to adapt the technology.
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1. Select Export Setup.

The Export Setup file selection dialog box appears, as shown in Figure 3-27.

Figure 3-27 Export Setup File Selection Dialog Box

2. Follow the instructions given in File Selection Dialog Boxes on page 23to select a filename.

The default file name is default.tct.

3. Click on OKto save the file.

Saving the Technology Description

The final step in using QRC TCT is to generate a technology description that can be used byQRC. The technology description file is called SCtechnology.XXX, where XXXis a user-defined extension. You can save the technology file in an Encrypted format.

If you choose this format, you can see the global parameters such as regions and cross-sections with a text editor, but all technological parameters are in encrypted format, which isunreadable. You can use one of two ways to save the technology description in encryptedformat:

Select Session Export Description Encrypted.
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Click on the button on the icon bar.

1. Using the method just described, select the output format.

A file selection dialog box opens, asking you to specify the location and the file name ofthe technology description file. Usually technology description files are namedSCtechnology.XXXX, where the XXXXextension gives additional information on thetechnology.


3. Move to an appropriate directory, and type in a file name, for example,SCtechnology.bicmos.crypt.

4. Click on OKto start the export routine.
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4

Commands

This chapter describes the commands that are available in QRC TCTs graphical userinterface menus.

Session MenuThe Session menu is shown in Figure 4-1 on page 57.

Figure 4-1 Session Menu

New Session

The Session New Sessioncommand clears the current database and starts a newsession. If the $ASSURAHOME/share/sna/TCTtemplates directory contains template files,the template file selection window shown in Figure 4-2 on page 58appears. If no templatefiles are available, only the database is cleared, and all variables are reset.


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QRC Substrate Technology Characterization ManualCommands


Figure 4-2 Template File Selection Window

Load Session

The Session LoadSessioncommand loads an existing QRC TCT session. It activatesa file selection dialog box that enables you to select the session to load. See File SelectionDialog Boxes on page 23for instructions on using this dialog box.

Save Session

The Session Save Sessioncommand saves the current QRC TCT session. It activatesa file selection dialog box that enables you to select the session to save. See File SelectionDialog Boxes on page 23for instructions on using this dialog box.

Revert to Saved

The Session Revert to Savedcommand restarts a session from the point at which youpreviously saved it, discarding any changes you may have made subsequently.

Export

The Session Exportcommand saves the technology description. It activates the Exportmenu, shown in Figure 4-3 on page 59.
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Figure 4-3 Export Menu

Setup

The Session Export Setupcommand allows you save a session as a template file. It

activates a file selection dialog box so that you can select a file name for it. See File SelectionDialog Boxes on page 23for instructions on using this dialog box.

Description

The Session Export Descriptioncommand saves the technology file in an encryptedformat.

Encrypted

The Session Export Description Encryptedcommand saves the technology file ina format that enables you to see the global parameters like regions and cross-sections witha text editor, but all technological parameters are in encrypted format, which is unreadable.

Exit

The Session Exitcommand exits QRC TCT. It brings up the confirmation box shown inFigure 4-4 on page 59.

Figure 4-4 Exit QRC TCT Confirmation Box
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Options Menu

Figure 4-5 on page 60shows the Options menu.

Figure 4-5 Options Menu

Default Directory

The Options Default Directorycommand specifies the default directory for storing doping

profiles. It activates a file selection dialog box so you can select the name of the directory. SeeFile Selection Dialog Boxes on page 23for instructions on using file selection dialog boxesin QRC TCT.

Discretization

The Options Discretizationcommand enables you to change the discretizationparameters. It activates the Discretization dialog box, shown in Figure 4-6 on page 61.
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Figure 4-6 Discretization Dialog Box

The Discretization dialog box contains the following fields:

Backside Depth

Changes the depth of the backside, that is, the thickness of the die. It is given in microns.

Temperature

Specifies the operation temperature, in degrees Celsius or Kelvin.


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Mobility tuning

The mobility tuning factor takes into consideration any changes in mobility in the process

to ensure that the doping information is translated into accurate resistivity information.There are separate tuning commands for electrons and holes

Mobility tuning for holes

This command specifies a tuning factor for holes to allow you to tune the internalcalculation of resistivity of the Substrate technology file.

Mobility tuning for electrons

This command specifies a separate tuning factor for electrons to allow you to tunethe internal calculation of resistivity of the Substrate technology file.

Tuning for junction capacitors

Specify a positive value which acts as a linear scaling factor, or tuning factor, for junctioncapacitors extracted during substrate extraction in the QRC AoT flow. The default valueis 1.0.

Number of Subdivisions

Defines the number of subdivisions above and below the critical depth. The critical depthis the distance from the surface of the substrate to the border of the homogenous dopingconcentration.

SamplingSamples the doping concentration profiles to define several substrate layers. You candefine the sampling in either of two ways:

Step

Samples the doping profiles with a constant step width. The units are given inmicrons.

Sample

Samples the doping profiles with a certain number of samples.

Transition Tolerance

Specifies the tolerance to use for p-n transitions in the doping profiles. The dopingprofiles must show the transition between areas dominated by electrons and areasdominated by holes at the same vertical depth. Sometimes doping concentration profilesderived from measurements do not lead to a sufficient overlap of the transitions because


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of measurement deviations. This parameter allows you to set some tolerance in thetransition, in microns.

CompressSpecifies where the subdivisions are concentrated. This compression factor influencesthe calculation of the subdivisions. A value less than 1 concentrates the subdivisions inthe vicinity of the p-n transition. A value greater than 1 concentrates the subdivisions atthe surface of the substrate.

Maximum Junction Potential Drop

Sets the maximum allowable potential dro

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