Dynamic channel hot-carrier degradation of NMOS transistors by enhanced electron-hole injection into the oxide

Hot-carrier stressing has been carried out on NMOS transistors under dynamic stressing conditions in which the drain voltage is kept constant and a square wave is applied to the gate such that electrons are injected into the oxide during the upper part of the cycle, while the lower part is varied so as to vary the oxide hole current. It is found that maximum degradation occurs when the hole current is maximum, indicating that the injection of both holes and electrons into the oxide is necessary for enhanced surface state generation, and supporting the model by which the trapping of holes and the subsequent neutralization by injected electrons leads to the formation of interface states.