SIMULATION OF VELOCITY OVERSHOOT AND HOT CARRIER EFFECTS IN THIN-FILM SOI-NMOSFETS

The velocity overshoot and hot carrier effects in thin-film SOI-nMOSFETs have been studied using a two-dimensional device simulator based on the energy transport model. It has been found that the velocity overshoot effect in a nearly-intrinsic device becomes pronounced in the thort channel region because of their high carrier mobility. The distribution of the electron velocity in a 0.2 mum channel length SOI device shows that the velocity overshoot takes place over the whole channel region, which enhances the drive capability significantly. The behaviors of hot carriers injected into the gate oxide and the back oxide have been simulated for the first time by using the energy distribution functions of electrons and holes at the SOI-SiO2 interface and solving the current continuity equation in the oxide layer. It has been found that hot carriers are injected not only into the gate oxide but also into the back oxide, which can degrade hot-carrier reliability in small-featured thin-film SOI-MOSFETs.