Operation and Modeling of the MOS Transistor

Description

Operation and Modeling of the MOS Transistor has become a standard in academia and industry. Extensively revised and updated, the third edition of this highly acclaimed text provides a thorough treatment of the MOS transistor--the key element of modern microelectronic chips.

New to this Edition

• Energy bands and the energy barrier viewpoint are integrated into the discussion in a smooth, simple manner
• Expanded discussion of small-dimension effects, including velocity saturation, drain-induced barrier lowering, ballistic operation, polysilicon depletion, quantum effects, gate tunneling current, and gate-induced drain leakage
• Expanded discussion of small-signal modeling, including gate and substrate current modeling and flicker noise
• New chapter on substrate nonuniformity and structural effects, discussing transversal and lateral (halo) doping nonuniformity, stress and well proximity effects, and statistical variability
• A completely re-written chapter on modeling for circuit simulation, covering the considerations and pitfalls in the development of models for computer-aided design
• Extensively updated bibliography
• An accompanying website includes additional details not covered in the text, as well as model computer code

Table of Contents

PREFACE

CHAPTER 1: REVIEW OF FUNDAMENTALS AND MOSFET OVERVIEW

1.1 Introduction

1.2 Semiconductors
1.2.1 Intrinsic Semiconductors, Free Electrons, and Holes
1.2.2 Extrinsic Semiconductors
1.2.3 Equilibrium in the Absence of Electric Field
1.2.4 Equilibrium in the Presence of Electric Field
1.2.5 Nonequilibrium; Quasi-Fermi Levels
1.2.6 Relations between Charge Density, Electric Field, and Potentials; Poisson's Equation

1.3 Conduction
1.3.1 Transit Time
1.3.2 Drift
1.3.3 Diffusion
1.3.4 Total Current

1.4 Contact Potentials

1.5 The pn Junction

1.6 Overview of the MOS Transistor
1.6.1 Basic Structure
1.6.2 A Qualitative Description of MOS Transistor Operation
1.6.3 A Fluid Dynamical Analog
1.6.4 MOS Transistor Characteristics

1.7 Fabrication Processes and Device Features

1.8 A Brief Overview of This Book

References
Problems

CHAPTER 2: THE MOS CAPACITOR

2.1 Introduction

2.2 The Flatband Voltage

2.3 Potential Balance and Charge Balance

2.4 Effect of Gate-Body Voltage on Surface Condition
2.4.1 Flatband Condition
2.4.2 Accumulation
2.4.3 Depletion and Inversion
2.4.4 General Analysis

2.5 Accumulation and Depletion

2.6 Inversion
2.6.1 General Relations and Regions of Inversion
2.6.2 Strong Inversion
2.6.3 Weak Inversion
2.6.4 Moderate Inversion

2.7 Small-Signal Capacitance

2.8 Summary of Properties of the Regions of Inversion

References
Problems

CHAPTER 3: THE THREE-TERMINAL MOS STRUCTURE

3.1 Introduction

3.2 Contacting the Inversion Layer

3.3 The Body Effect

3.4 Regions of Inversion
3.4.1 Approximate Limits
3.4.2 Strong Inversion
3.4.3 Weak Inversion
3.4.4 Moderate Inversion

3.5 A "V[C[B Control" Point of View
3.5.1 Fundamentals
3.5.2 The "Pinchoff Voltage"

References
Problems

CHAPTER 4: THE FOUR-TERMINAL MOS TRANSISTOR

4.1 Introduction

4.2 Transistor Regions of Operation

4.3 Complete All-Region Model

4.4 Simplified All-Region Models
4.4.1 Linearizing the Depletion Region Charge
4.4.2 Body-Referenced Simplified All-Region Models
4.4.3 Source-Referenced Simplified All-Region Models
4.4.4 Charge Formulation of Simplified All-Region Models

4.5 Models Based on Quasi-Fermi Potentials

4.6 Regions of Inversion in Terms of Terminal Voltages

4.7 Strong Inversion
4.7.1 Complete Strong-Inversion Model
4.7.2 Body-Referenced Simplified Strong-Inversion Model
4.7.3 Source-Referenced Simplified Strong-Inversion Model
4.7.4 Model Origin Summary

4.8 Weak Inversion
4.8.1 Special Conditions in Weak Inversion
4.8.2 Body-Referenced Model
4.8.3 Source-Referenced Model

4.9 Moderate-Inversion and Single-Piece Models

4.10 Source-Referenced vs. Body-Referenced Modeling

4.11 Effective Mobility

4.12 Effect of Extrinsic Source and Drain Series Resistances

4.13 Temperature Effects

4.14 Breakdown

4.15 The p-Channel MOS Transistor

4.16 Enhancement-Mode and Depletion-Mode Transistors

4.17 Model Parameter Values, Model Accuracy, and Model Comparison

References
Problems

CHAPTER 5: SMALL-CHANNEL AND THIN OXIDE EFFECTS

5.1 Introduction

5.2 Carrier Velocity Saturation

5.3 Channel Length Modulation

5.4 Charge Sharing
5.4.1 Introduction
5.4.2 Short-Channel Devices
5.4.3 Narrow-Channel Devices
5.4.4 Limitations of Charge-Sharing Models

5.5 Drain-Induced Barrier Lowering

5.6 Punchthrough

5.7 Combining Several Small-Dimension Effects into One Model--A Strong-Inversion Example

5.8 Hot Carrier Effects; Impact Ionization

5.9 Velocity Overshoot and Ballistic Operation

5.10 Polysilicon Depletion

5.11 Quantum Mechanical Effects

5.12 DC Gate Current

5.13 Junction Leakage; Band-to-Band Tunneling; GIDL

5.14 Leakage Currents--Particular Cases

5.15 The Quest for Ever-Smaller Devices
5.15.1 Introduction
5.15.2 Classical Scaling
5.15.3 Modern Scaling

References
Problems

CHAPTER 6: LARGE-SIGNAL MODELING OF THE MOS TRANSISTOR IN TRANSIENT OPERATION

6.1 Introduction

6.2 Quasi-Static Operation

6.3 Terminal Currents in Quasi-Static Operation

6.4 Evaluation of Intrinsic Chargers in Quasi-Static Operation
6.4.1 Introduction
6.4.2 Strong Inversion
6.4.3 Moderate Inversion
6.4.4 Weak Inversion
6.4.5 All-Region Model
6.4.6 Depletion and Accumulation
6.4.7 Plots of Charges vs. V[G[S

6.5 Transit Time under DC Conditions

6.6 Limitations of the Quasi-Static Model

6.7 Non-Quasi-Static Modeling
6.7.1 Introduction
6.7.2 The Continuity Equation
6.7.3 Non-Quasi-Static Analysis

6.8 Extrinsic Parasitics
6.8.1 Extrinsic Capacitances
6.8.2 Extrinsic Resistance
6.8.3 Temperature Dependence
6.8.4 Simplified Models

References
Problems

CHAPTER 7: SMALL-SIGNAL MODELING FOR LOW AND MEDIUM FREQUENCIES

7.1 Introduction

7.2 A Low-Frequency Small-Signal Model for the Intrinsic Part
7.2.1 Introduction
7.2.2 Small-Signal Model for the Drain-to-Source Current
7.2.3 Small-Signal Model for the Gate and Body Currents
7.2.4 Complete Low-Frequency Small-Signal Model for the Intrinsic Part
7.2.5 Strong Inversion
7.2.6 Weak Inversion
7.2.7 Moderate Inversion
7.2.8 All-Region Models

7.3 A Medium-Frequency Small-Signal Model for the Intrinsic Part
7.3.1 Introduction
7.3.2 Intrinsic Capacitances

7.4 Including the Extrinsic Part

7.5 Noise
7.5.1 Introduction
7.5.2 White Noise
7.5.3 Flicker Noise
7.5.4 Noise in Extrinsic Resistances
7.5.5. Including Noise in Small-Signal Circuits

7.6 All-Region Models

References
Problems

CHAPTER 8: SMALL-SIGNAL MODELING FOR HIGH-FREQUENCY OPERATION

8.1 Introduction

8.2 A Complete Quasi-Static Model for the Intrinsic Part
8.2.1 Complete Description of Intrinsic Capacitance Effects
8.2.2 Small-Signal Equivalent Circuit Topologies
8.2.3 Evaluation of Capacitances
8.2.4 Frequency Region of Validity

8.3 y-Parameter Models

8.4 Non-Quasi-Static Models
8.4.1 Introduction
8.4.2 A Non-Quasi-Static Strong-Inversion Model
8.4.3 Other Approximations and Higher-Order Models
8.4.4 Model Comparison

8.5 High-Frequency Noise

8.6 Consideration in

References
Problems

CHAPTER 9: SUBSTRATE NONUNIFORMITY AND OTHER STRUCTURAL EFFECTS

9.1 Introduction

9.2 Ion Implantation and Substrate Nonuniformity

9.3 Substrate Transverse Nonuniformity
9.3.1 Preliminaries
9.3.2 Threshold Voltage
9.3.3 Drain Current
9.3.4 Buried-Channel Devices

9.4 Substrate Lateral Nonuniformity

9.5 Well Proximity Effect

9.6 Stress Effects

9.7 Statistical Variability

References
Problems

CHAPTER 10: MODELING FOR CIRCUIT SIMULATION

10.1 Introduction

10.2 Types of Models
10.2.1 Models for Device Analysis and Design
10.2.2 Device Models for Circuit Simulation

10.3 Attributes of Good Compact Models

10.4 Model Formulation
10.4.1 General Consideration and Choices

10.5 Model Implementation in Circuit Simulators

10.6 Model Testing

10.7 Parameter Extraction

10.8 Simulation and Extraction for RF Applications

10.9 Common MOSFET Models Available in Circuit Simulators
10.9.1 BSIM
10.9.2 EKV
10.9.3 PSP
10.9.4 Other Models

References
Problems

APPENDICES
A. Basic Laws of Electrostatic in One Dimension
B. Quasi-Fermi Levels and Currents
C. General Analysis of the Two-Terminal MOS Structure
D. Careful Definitions for the Limits of Moderate Inversion
E. General Analysis of the Three-Terminal MOS Structure
F. Drain Current Formulation Using Quasi-Fermi Potentials
G. Modeling Based on Pinchoff Voltage and Related Topics
H. Evaluation of the Intrinsic Transient Source and Drain Currents
I. Quantities Used in the Derivation of the Non-Quasi-Static y-Parameter Model
K. Analysis of Buried-Channel Devices
L. MOSFET Model Benchmark Tests

INDEX