A new simplified two-dimensional model for the threshold voltage of MOSFET's with nonuniformly doped substrate

1 June 1991

journal article
Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Electron Devices

Vol. 38 (6) , 1376-1383
https://doi.org/10.1109/16.81629

Abstract

A new simplified two-dimensional model for the threshold voltage of MOSFETs is derived in terms of simple characteristic functions. These characteristic functions are transformed from the exact series solution of the two-dimensional Poisson's equation, in which the effects of a nonuniformly doped substrate and a finite graded source-drain junction depth are included. In this model, charge-screening effects are proposed to account for the weak dependence of the threshold voltage on the substrate bias for short-channel MOSFETs, and exact source and drain boundary potentials can be approximated by their equivalent power functions. The accuracy of the simplified 2-D model is verified by 2-D numerical analysis. Moreover, comparisons between the simplified 2-D model and the experimental results are made, and good agreement is obtained for wide ranges of channel lengths, applied substrate, and drain biases

Keywords

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