Learn the basic properties and designs of modern VLSI devices, as well as the factors affecting performance, with this thoroughly updated second edition. The first edition has been widely adopted as a standard textbook in microelectronics in many major US universities and worldwide. The internationally-renowned authors highlight the intricate interdependencies and subtle tradeoffs between various practically important device parameters, and also provide an in-depth discussion of device scaling and scaling limits of CMOS and bipolar devices. Equations and parameters provided are checked continuously against the reality of silicon data, making the book equally useful in practical transistor design and in the classroom. Every chapter has been updated to include the latest developments, such as MOSFET scale length theory, high-field transport model, and SiGe-base bipolar devices.

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Fundamentals of Modern VLSI Devices

We present a continuous analytic current-voltage (I-V) model for cylindrical undoped (lightly doped) surrounding gate (SGT) MOSFETs. It is based on the exact solution of the Poisson's equation, and the current continuity equation without the charge-sheet approximation, allowing the inversion charge distribution in the silicon film to be adequately described. It is valid for all the operation regions (linear, saturation, subthreshold) and traces the transition between them without fitting parameters, being ideal for the kernel of SGT MOSFETs compact models. We have demonstrated that the I-V characteristics obtained by this model agree with three-dimensional numerical simulations for all ranges of gate and drain voltages.

Continuous analytic I-V model for surrounding-gate MOSFETs

We present an analytical and continuous dc model for cylindrical undoped surrounding-gate (SGT) MOSFETs in which the channel current is written as an explicit function of the applied voltages. The model is based on a new unified charge control model developed for this device. The explicit model shows good agreement with the numerical exact solution obtained from the new charge control model, which was previously validated by comparison with three-dimensional numerical simulations.

Explicit continuous model for long-channel undoped surrounding gate MOSFETs

This paper presents an analytic potential model for long-channel symmetric and asymmetric double-gate (DG) MOSFETs. The model is derived rigorously from the exact solution to Poisson's and current continuity equation without the charge-sheet approximation. By preserving the proper physics, volume inversion in the subthreshold region is well accounted for in the model. The resulting analytic expressions of the drain-current, terminal charges, and capacitances for long-channel DG MOSFETs are continuous in all operation regions, i.e., linear, saturation, and subthreshold, making it suitable for compact modeling. As no fitting parameters are invoked throughout the derivation, the model is physical and predictive. All parameter formulas are validated by two-dimensional numerical simulations with excellent agreement. The model has been implemented in Simulation Program with Integrated Circuit Emphasis version 3 (SPICE3), and the feasibility is demonstrated by the transient analysis of sample CMOS circuits.

An analytic potential model for symmetric and asymmetric DG MOSFETs

We propose a design oriented charge-based model for undoped DG MOSFETs under symmetrical operation that aims at giving a comprehensive understanding of the device from the design strategy. In particular, we introduce useful normalizations for current and charges that in turn lead to very simple relationships among the physical quantities. Finally, we emphasize on the link that exists between this approach and the EKV formalism derived for bulk MOSFETs, which in turn leads to the unique gms/ID design methodology for DG architectures. © 2004 Elsevier Ltd. All rights reserved.

A Design Oriented Charge-based Current Model for Symmetric DG MOSFET and its Correlation with the EKV Formalism

This letter presents a continuous analytic current-voltage (I-V) model for double-gate (DG) MOSFETs. It is derived from closed-form solutions of Poisson's equation, and current continuity equation without the charge-sheet approximation. The entire I/sub ds/(V/sub g/,V/sub ds/) characteristics for all regions of MOSFET operation: linear, saturation, and subthreshold, are covered under one continuous function, making it ideally suited for compact modeling. By preserving the proper physics, this model readily depicts "volume inversion" in symmetric DG MOSFETs-a distinctively noncharge-sheet phenomenon that cannot be reproduced by standard charge-sheet based I-V models. It is shown that the I-V curves generated by the analytic model are in complete agreement with two-dimensional numerical simulation results for all ranges of gate and drain voltages.

A continuous, analytic drain-current model for DG MOSFETs

A two-dimensional (2-D) analytical solution of electrostatic potential is derived for undoped (or lightly doped) double-gate (DG) MOSFETs in the subthreshold region by solving Poissons equation in a 2-D boundary value problem. It is shown that the subthreshold current, short-channel threshold voltage rolloff and subthreshold slope predicted by the analytical solution are in close agreement with 2-D numerical simulation results for both symmetric and asymmetric DG MOSFETs without the need of any fitting parameters. The analytical model not only provides useful physics insight into short-channel effects, but also serves as basis for compact modeling of DG MOSFETs.

A 2-D analytical solution for SCEs in DG MOSFETs

Compact models of short channel effect in symmetric and asymmetric double gate MOSFETs are developed by solving two-dimensional (2-D) Poisson’s equation as a boundary value problem in the subthreshold region. The subthreshold current is obtained through the 2-D analytic potential distribution function. Threshold voltage rolloff, drain induced barrier lowering (DIBL) and subthreshold slope degradation as a function of channel length are extracted from the subthreshold current expression. The short channel effect model is validated by 2-D numerical simulation and incorporated into the analytical potential model for DG MOSFETs.

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Xiaoping Liang

Papers

A continuous, analytic drain-current model for DG MOSFETs

A 2-D analytical solution for SCEs in DG MOSFETs

Compact Modeling of Short Channel Double-Gate MOSFETs