Nanotech 2006 Vol. 3
Nanotech 2006 Vol. 3
Technical Proceedings of the 2006 NSTI Nanotechnology Conference and Trade Show, Volume 3

Compact Modeling Chapter 7

Accuracy of Surface-Potential-Based Long-Wide-Channel MOS Transistor Compact Models

Authors: B.B. Jie and C-T Sah

Affilation: University of Florida, United States

Pages: 622 - 637

Keywords: surface potential compact model, bulk charge approximations, percentage-RMS-deviation, non-compact baseline model

Frequently asked questions are addressed, “How accurate are the approximate long-and-wide-channel MOS transistors baseline models that have been used to develop the compact models for computer-aided circuit designs?” Three commonly used surface-potential (US=q*PSIS/kT) approximations of the bulk-charge, QB (&#8801; QP for p-Base of nMOST), are evaluated: QB &#61621; (i) (US)^(1/2) and (ii) (US&#8722;1)^(1/2), and (iii) [US&#8722;1+exp(&#8722;US)]^(1/2). Several new approximations are also evaluated. Self-consistent remote charge-neutrality boundary-condition and minority carriers are taken into account. Percentage-deviation and percentage-RMS-deviation of the DC drain current and the drain- and trans-conductances from the non-compact baseline model (long-and-wide-channel, and space-constant impurity-concentration and oxide-thickness) are computed for the engineering ranges of the body impurity concentration and oxide thickness (10^16 to 10^19 cm&#8722;3 and 1 to 30 nm). Approximation (i) shows significant deviations, ~16% at threshold diverging rapidly with deepening into the subthreshold range. Approximations (ii) and (iii) show a few percent (1% to 2%) deviations in both inversion and subthreshold ranges, while (ii) diverges as US &#8594;1+ or PSIS &#8594; kT/q above flatband. In the accummulation range, US<0, better approximations are needed.

ISBN: 0-9767985-8-1
Pages: 913
Hardcopy: $119.95