Influence of carrier velocity related parameters on the propagation delay time of inverters with high- k gate dielectric CMISFETs

Abstract

It has been reported that mobility ( μ eff) in high- k gate dielectric metal insulator semiconductor field effect transistors (MISFETs) is lower than that in conventional metal oxide semiconductor field effect transistors (MOSFETs). We investigated the influence of carrier velocity related parameters (CVRP), such as μ eff in the high vertical electric field ( E eff) region where gate voltage is around power supply voltage, μ eff in the low E eff region where gate voltage is around threshold voltage, and saturation velocity ( V SAT), on propagation delay time ( τ pd) of CMIS inverters using a circuit simulation. It is shown that τ pd is strongly affected by μ eff in the high E eff region and that influences of μ eff in the low E eff region and V SAT on τ pd are relatively small. Physical reasons for these phenomena are understood based on consideration of influences of mobility and saturation velocity on drain current taking the effect of channel length modulation into consideration.