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

摘要

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.