An Investigation on Anomalous Hot-Carrier-Induced On-Resistance Reduction in n-Type LDMOS Transistors

In this paper, on-resistance (Ron) degradation induced by hot-carrier injection in n-type lateral diffused metal-oxide-semiconductor transistors with shallow trench isolation (STI) in the drift region is investigated.Ronunexpectedly decreases under medium- and high-gate voltage (Vgs) stress conditions. According to experimental data and technology computer-aided-design simulation results, the mechanisms responsible for anomalousRonshift are proposed. When the device is stressed under mediumVgs, hot-hole injection and trapping occur at the STI edge closest to the channel, resulting inRonreduction. Interface trap generation (¿Nit) occurs at the STI edge closest to the channel and nearby drift region, leading toRonincrease. For the device stressed under highVgs,Ronreduction is also attributed to hole trapping at the STI corner closest to the channel. ¿Nitcreated by hot-electron injection at the STI edge closest to the drain dominates device characteristics and leads toRonincrease eventually. Based on the proposedRondegradation mechanisms, anRondegradation model is discussed and verified with experimental data.