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

In this paper, on-resistance (R _on) 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. R _on unexpectedly decreases under medium- and high-gate voltage (V _gs) stress conditions. According to experimental data and technology computer-aided-design simulation results, the mechanisms responsible for anomalous R _on shift are proposed. When the device is stressed under medium V _gs, hot-hole injection and trapping occur at the STI edge closest to the channel, resulting in R _on reduction. Interface trap generation (??N _it) occurs at the STI edge closest to the channel and nearby drift region, leading to R _on increase. For the device stressed under high V _gs, R _on reduction is also attributed to hole trapping at the STI corner closest to the channel. ??N _it created by hot-electron injection at the STI edge closest to the drain dominates device characteristics and leads to R _on increase eventually. Based on the proposed R _on degradation mechanisms, an R _on degradation model is discussed and verified with experimental data.