Comparison of Gate-Metal Work Function Variability Between Ge and Si p-Channel FinFETs

In this paper, for the first time, the performance of a Ge p-channel FinFET in the presence of random grain-orientation-induced gate-metal work function variability (WFV) is reported. The statistical fluctuation in threshold voltage (VT) and subthreshold swing (SS) are estimated for a Ge p-FinFET of varying channel length, fin width, equivalent oxide thickness of the gate dielectric, and supply voltage using a 3-D numerical device simulator, and compared with that for a similarly sized Si p-FinFET. The results indicate that the Ge FinFET shows better immunity to WFV-induced VT fluctuations, whereas a higher variation in SS is observed for such devices as compared with its Si counterpart.