An approach for quantum mechanical modeling and simulation for MOS devices, covering the whole operation region

Abstract

A quantum mechanical (QM) approach for modeling and simulation of MOS devices, covering the whole operation region, was proposed. This formulation is applicable continuously from the subthreshold to the saturation regions, since it exactly treats the QM effects on the in-depth distribution of the gate induced carriers in the channel by solving one dimensional Poisson equation and Schrödinger equation self-consistently and it treats the lateral drift–diffusion transport using quasi-Fermi potential. A QM simulator was implemented using this QM approach. This QM simulator was verified by classical three-dimensional device simulator, CADDETH, in the whole range of operation of bulk MOSFET with low dopant density where QM effect is negligible. The QM simulation elucidated that the threshold voltage shift in thin SOI MOSFETs in saturation region as well as in linear region results from energy shift of the lowest conduction electron level and effective increase of gate oxide thickness.