A general model of the thin-film SOI-MOSFET

Abstract

A model for a thin-film SOI MOSFET which is valid in all regions of inversion is presented. It takes into account all conditions at the back surface of the silicon film, including inversion. To achieve an analytical expression for the inversion layer charge as a function of the front and back surface potentials, the contribution of the accumulation layer to the total charge is neglected. Two-dimensional simulation results show that the variations of the front and back surface potentials along the channel are nearly equal. This simplifies the integration of the inversion layer charge along the channel, resulting in explicit formulas for the drift and diffusion terms of the drain current in both channels. The SOI-MOSFET model offers all features known from the charge sheet model. Due to the accurate computation of the surface potentials and the inclusion of the leakage current at the back interface the model gives an improved description of the substrate bias influence on transistor operation.<>