A simple model for short-channel effects of a buried-channel MOSFET on the buried insulator

Abstract

A majority-carrier distribution model and a channel potential-profile model, in which the barrier-lowering effect is taken into account, are proposed for a buried-channel MOSFET (BC-MOSFET/ SOI). Simple expressions for threshold voltage and drain breakdown voltage were derived from the models for a short-channel BC-MOSFET/ SOI. The comparison between theory and experimental results shows reasonable agreement. The drain-bias coefficient γ of threshold voltage for BC-MOSFET's/ SOI is approximately proportional to TN D -1L eff -2, where T, N D , and L eff are the temperature, the doping concentration in the channel region, and the channel length, respectively. The coefficient γ depends slightly on the drain bias. BC-MOSFET's/SOI are able to be more miniaturized than surface-channel MOSFET's (SC-MOSFET's) at the small power source voltage, and SC-MOSFET's are able to be more miniaturized than BC-MOSFET's/SOI at the large drain bias. It is shown that the conventional, simple scaling scheme, which holds the constant electric field, is not applicable to BC-MOSFET's/SOI. The power source voltage has to be fixed when dimensions and doping concentrations are scaled down. On the other hand, only the channel region thickness has to be fixed when the power source voltage is scaled down.