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

It has been reported that mobility (μeff) 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 μeff in the high vertical electric field (Eeff) region where gate voltage is around power supply voltage, μeff in the low Eeff region where gate voltage is around threshold voltage, and saturation velocity (VSAT), on propagation delay time (τpd) of CMIS inverters using a circuit simulation. It is shown that τpd is strongly affected by μeff in the high Eeff region and that influences of μeff in the low Eeff region and VSAT on τpd 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.