Gate-oxide thickness dependence of hot-carrier-induced degradation in buried p-MOSFET's

The gate-oxide thickness dependence of hot-carrier-induced degradation in buried p-MOSFETs is described. The results reveal that the thinner gate oxide provides higher hot-carrier resistance even with high hot-electron generation. A significant improvement of the threshold voltage shift is obtained for a buried p-MOSFET with a thin gate oxide of 7 nm at a wide range of stress gate voltages. This effect is induced by a significantly different mechanism from that of n-MOSFETs. The mechanism is explained by using a numerical degradation simulation, which self-consistently includes the models for the hot-carrier transport in silicon, emission process, carrier behavior in the oxide, and carrier trapping. It is found that the degradation of the buried p-MOSFETs is characterized by the dynamics of the electron heating process during stress and the corresponding position of the trapped electrons.>