Effect of the MOS Process on the Work-Function Difference Between the Polysilicon Gates and the Silicon Substrate

Polysilicon gates are an important element of modem MOS integrated circuit technology. The workfunction difference (ϕps) between the polysilicon gate and the silicon substrate is a vital parameter of the MOS system because it determines the threshold voltage of the field-effect transistor. Ideally, ϕps is determined by the doping level in both polysilicon and the substrate. In reality process variations influence the ϕPS in a tangible way. Some of these effects are reviewed in the present paper.