Mechanism of hot electron induced degradation in LDD NMOS-FET

The hot electron induced degradation of the N-channel LDD MOS-FETs was studied and compared with the conventional one. The LDD NMOS-FET has its own degradation mode, the decrease of the trans-conductance and the drain current. This mechanism of the degradation was clarified by the reliability tests and the 2-dimensional device simulation considering the drift of the injected electrons in the gate oxide. Most of the generated surface states were localized near the drain edge and modulate the parasitic drain resistance of the LDD NMOS-FET, but do not affect the conventional one.