Influence of polysilicon-gate depletion on the subthreshold behavior of submicron MOSFETs

摘要

Ion implantation, followed by annealing process, often leads to nonumiform doping and considerable depletion effect in the polysilicon gate of submicron MOS devices. Such an effect can alter notably the subthreshold characteristics and invalidate the conventional subthreshold current model. This paper studies the polysilicon-gate depletion effects on the subthreshold behavior based on results obtained from two-dimensional device simulation. An empirical expression is also suggested to describe the subthreshold current including the depletion effect.