Convergence of hot-carrier-induced saturation region drain current and on-resistance degradation in drain extended MOS transistors

Hot-carrier-induced device degradation in n-type high-voltage drain-extended MOS (DEMOS) devices stressed under high drain voltage and high gate voltage (V_g) is investigated. Charge pumping data and technology computer-aided-design simulation results reveal that hot-carrier-induced interface state formation in the gate overlapped shallow trench isolation region is responsible for device degradation. Furthermore, an unexpected high saturation region drain current (I_d(sat)) degradation (close to on-resistance degradation) is observed. The occurrence of quasi-saturation under high V_g bias is the cause of significant I_d(sat) degradation. The results presented in this paper suggest that severe I_d(sat) degradation may become a reliability concern for devices exhibiting the quasi-saturation phenomenon.