Improved performance of FDSOI FETs at cryogenic temperatures by optimizing ion implantation into silicide

Band tailing is a critical issue for cryogenic CMOS, which significantly degrades the performance of conventional MOSFETs at cryogenic temperature. The band tail arises primarily due to Gaussian-distributed localized states, which can be induced by ion implantation during source/drain formation. In this study, we investigate the impact of various ion implantation schemes on the subthreshold behavior of cryogenic fully depleted (FD) SOI MOSFETs. By optimizing the ion implantation into silicide (IIS) process, we were able to reduce the density of localized states and achieve a steep switching performance at 5 K. We systematically examine the effects of ion implantation angle and activation temperature of IIS on the device performance at cryogenic temperatures.