RF and hot carrier effects in metal gate/high-k dielectric nMOSFETs at cryogenic temperature

Abstract

We investigate RF performances and hot carrier effects of nMOSFETs at cryogenic temperature. RF performances of HfO 2 dielectric nMOSFET at 77 K are improved more than those of SiO 2 dielectric nMOSFET although DC performances are improved similarly. The nMOSFET with HfO 2 dielectric has 127.4 GHz f T and 75.4 GHz f max at 77 K. In hot carrier injection measurement, g m of HfO 2 nMOSFET at 77 K is degraded more than 300 K although V th shift is less. The cause of g m reduction is discussed related to the trapping.