Mosfet Modeling & Bsim3 User's Guide

by Cheng, Yuhua; Hu, Chenming

• ISBN13: 9780792385752
• ISBN10: 0792385756
• Format: Hardcover
• Copyright: 1999-08-01
• Publisher: Kluwer Academic Pub

Summary

Circuit simulation is essential in integrated circuit design, and the accuracy of circuit simulation depends on the accuracy of the transistor model. BSIM3v3 (BSIM for Berkeley Short-channel IGFET Model) has been selected as the first MOSFET model for standardization by the Compact Model Council, a consortium of leading companies in semiconductor and design tools. In the next few years, many fabless and integrated semiconductor companies are expected to switch from dozens of other MOSFET models to BSIM3. This will require many device engineers and most circuit designers to learn the basics of BSIM3. MOSFET Modeling & BSIM3 User's Guide explains the detailed physical effects that are important in modeling MOSFETs, and presents the derivations of compact model expressions so that users can understand the physical meaning of the model equations and parameters. It is the first book devoted to BSIM3. It treats the BSIM3 model in detail as used in digital, analog and RF circuit design. It covers the complete set of models, i.e., I-V model, capacitance model, noise model, parasitics model, substrate current model, temperature effect model and non quasi-static model. MOSFET Modeling & BSIM3 User's Guide not only addresses the device modeling issues but also provides a user's guide to the device or circuit design engineers who use the BSIM3 model in digital/analog circuit design, RF modeling, statistical modeling, and technology prediction. This book is written for circuit designers and device engineers, as well as device scientists worldwide. It is also suitable as a reference for graduate courses and courses in circuit design or device modelling. Furthermore, it can be used as a textbook for industry courses devoted to BSIM3. MOSFET Modeling & BSIM3 User's Guide is comprehensive and practical. It is balanced between the background information and advanced discussion of BSIM3. It is helpful to experts and students alike.

Table of Contents

Contents	v
Preface	xiii
Introduction	1	(12)
Compact MOSFET Modeling for Circuit Simulation	1	(4)
The Trends of Compact MOSFET Modeling	5	(8)
Modeling new physical effects	5	(1)
High frequency (HF) analog compact models	6	(1)
Simulation robustness and efficiency	7	(1)
Model standardization	8	(1)
References	8	(5)
Significant Physical Effects In Modern MOSFETs	13	(52)
MOSFET Classification and Operation	13	(5)
Strong inversion region (Vgs>Vth)	17	(1)
Weak and moderate inversion or the subthreshold region	18	(1)
Effects Impacting the Threshold Voltage	18	(12)
Non-uniform doping effects	19	(4)
Normal short channel effects	23	(1)
Reverse short channel effects	23	(2)
Normal narrow-width effects	25	(2)
Reverse narrow-width effects	27	(1)
Body bias effect and bulk charge effect	28	(2)
Channel Charge Theory	30	(7)
Accumulation	33	(1)
Depletion	33	(1)
Inversion	34	(3)
Carrier Mobility	37	(2)
Velocity Saturation	39	(2)
Channel Length Modulation	41	(3)
Substrate Current Due to Impact Ionization	44	(4)
Polysilicon Gate Depletion	48	(3)
Velocity Overshoot Effects	51	(2)
Self-heating Effect	53	(2)
Inversion Layer Quantization Effects	55	(10)
References	57	(8)
Threshold Voltage Model	65	(40)
Threshold Voltage Model for Long Channel Devices	65	(2)
Threshold Voltage Model with Short Channel Effects	67	(10)
Charge sharing model	68	(3)
Quasi 2-D models for drain induced barrier lowering effect	71	(6)
Narrow Width Effect Model	77	(3)
Threshold Voltage Model in BSIM3v3	80	(12)
Modeling of the vertical non-uniform doping effects	80	(3)
Modeling of the RSCE due to lateral non-uniform channel doping	83	(2)
Modeling of the short channel effect due to drain induced barrier lowering	85	(3)
Modeling of the narrow width effects	88	(2)
Complete Vth model in BSIM3v3	90	(2)
Helpful Hints	92	(13)
References	101	(4)
I-V Model	105	(38)
Essential Equations Describing the I-V Characteristics	105	(1)
Channel Charge Density Model	106	(8)
Channel charge model in the strong inversion region	106	(1)
Channel charge model in the subthreshold region	107	(2)
Continuous channel charge model of BSIMv3	109	(3)
Continuous channel charge model with the effect of Vds	112	(2)
Mobility Model	114	(3)
Piece-wise mobility models	114	(2)
Mobility models in BSIM3v3	116	(1)
I-V Model in the Strong Inversion Region	117	(7)
I-V model in the linear (triode) region	117	(1)
Drain voltage at current saturation, Vdsat	118	(2)
Current and output resistance in the saturation region	120	(4)
Subthreshold I-V Model	124	(1)
Single Equation I-V model of BSIMv3	125	(4)
Polysilicon Gate Depletion Effect	129	(1)
Helpful Hints	130	(13)
References	140	(3)
Capacitance Model	143	(68)
Capacitance Components in a MOSFET	144	(1)
Intrinsic Capacitance Model	145	(16)
Meyer model	145	(6)
Shortcomings of the Meyer model	151	(3)
Charge-based capacitance model	154	(7)
Extrinsic Capacitance Model	161	(2)
Capacitance Model of BSIM3v3	163	(34)
Long channel capacitance model (capMod=0)	164	(6)
Short channel capacitance (capMod=1)	170	(8)
Single-equation short channel capacitance model (capMod=2)	178	(8)
Short channel capacitance model with quantization effect (capMod=3)	186	(11)
Channel Length/Width in Capacitance Model	197	(1)
Helpful Hints	198	(13)
References	207	(4)
Substrate Current Model	211	(8)
Substrate Current Generation	211	(1)
Substrate Current Model in BSIM3v3	212	(3)
Helpful Hints	215	(4)
References	217	(2)
Noise Model	219	(24)
The Physical Mechanisms of Flicker (1/f) Noise	219	(1)
The Physical Mechanism of Thermal Noise	220	(1)
Flicker Noise Models in BSIM3v3	221	(8)
SPICE2 flicker noise model (noiMod=1)	221	(1)
Unified flicker noise model (noiMod=2)	222	(7)
Thermal Noise Models in BSIM3v3	229	(4)
Modified SPICE2 thermal noise model (noiMod=1)	230	(1)
BSIM3 thermal noise model (noiMod=2)	230	(3)
Helpful Hints	233	(10)
References	240	(3)
Source/Drain Parasitics Model	243	(20)
Parasitic Components in a MOSFET	243	(1)
Models of Parasitic Components in BSIM3v3	244	(10)
Source and drain series resistances	244	(4)
DC model of the source/drain diodes	248	(2)
Capacitance model of the source/bulk and drain/bulk diodes	250	(4)
Helpful Hints	254	(9)
References	261	(2)
Temperature Dependence Model	263	(18)
Temperature Effects in a MOSFET	263	(2)
Temperature Dependence Models in BSIM3v3	265	(5)
Comparison of the Temperature-Effect Models with Measured Data	270	(6)
Helpful Hints	276	(5)
References	279	(2)
Non-quasi Static (NQS) Model	281	(22)
The Necessity of Modeling NQS Effects	281	(3)
The NQS Model in BSIM3v3	284	(8)
Physics basis and model derivation	284	(5)
The BSIM3 NQS Model	289	(3)
Test Results of the NQS Model	292	(5)
Helpful Hints	297	(6)
References	301	(2)
BSIM3v3 Model Implementation	303	(24)
General Structure of BSIM3v3 Model Implementation	303	(3)
Robustness Consideration in the Implementation of BSIM3v3	306	(9)
Testing of Model Implementation	315	(2)
Model Selectors of BSIM3v3	317	(2)
Helpful Hints	319	(8)
References	324	(3)
Model Testing	327	(26)
Requirements for a MOSFET Model in Circuit Simulation	327	(2)
Benchmark Tests	329	(4)
Benchmark Test Results	333	(17)
Helpful Hints	350	(3)
References	351	(2)
Model Parameter Extraction	353	(22)
Overview of Model Parameter Extraction	353	(2)
Parameter Extraction for BSIM3v3	355	(12)
Optimization and extraction strategy	355	(1)
Extraction routines	355	(12)
Binning Methodology	367	(1)
Recommended Value Range of the Model Parameters	368	(4)
Automated Parameter Extraction Tool	372	(3)
References	373	(2)
RF and Other Compact Model Applications	375	(34)
RF Modeling	375	(18)
Modeling of the gate resistance	376	(7)
Modeling the substrate network	383	(2)
A RF MOSFET model based on BSIM3v3 for GHz communication IC's	385	(8)
Statistical Modeling	393	(6)
Technology Extrapolation and Prediction Using BSIM3 Model	399	(10)
References	406	(3)
Appendix A BSIM3v3 Parameter Table	409	(12)
A.1 Model control parameters	409	(1)
A.2 Process parameters	410	(1)
A.3 Parameters for Vth model	410	(1)
A.4 Parameters for I-V model	411	(3)
A.5 Parameters for capacitance model	414	(1)
A.6 Parameters for effective channel length/width in I-V model	415	(1)
A.7 Parameters for effective channel length/width in C-V model	416	(1)
A.8 Parameters for substrate current model	417	(1)
A.9 Parameters for noise models	417	(1)
A.10 Parameters for models of parasitic components	418	(1)
A.11 Parameters for models of temperature effects	419	(1)
A.12 Parameters for NQS model	420	(1)
Appendix B BSIM3v3 Model Equations	421	(28)
B.1 Vth equations	421	(1)
B.2 Effective Vgs-Vth	422	(1)
B.3 Mobility	423	(1)
B.4 Drain saturation voltage	423	(1)
B.5 Effective Vds	424	(1)
B.6 Drain current expression	424	(1)
B.7 Substrate current	425	(1)
B.8 Polysilicon depletion effect	426	(1)
B.9 Effective channel length and width	426	(1)
B.10 Drain/Source resistance	426	(1)
B.11 Capacitance model equations	426	(14)
B.12 Noise model equations	440	(3)
B.13 DC model of the source/drain diodes	443	(1)
B.14 Capacitance model of the source/bulk and drain/bulk diodes	444	(1)
B.15 Temperature effects	445	(2)
B.16 NQS model equations	447	(1)
B.17 A note on the poly-gate depletion effect	448	(1)
Appendix C Enhancements and Changes in BSIM3v3.1 versus BSIM3v3.0	449	(6)
C.1 Enhancements	449	(1)
C.2 Detailed changes	449	(6)
Appendix D Enhancements and Changes in BSIM3v3.2 versus BSIM3v3.1	455	(4)
D.1 Enhancements	455	(1)
D.2 Detailed changes	456	(3)
Index	459