Numerical simulation of static and dynamic operation performance of SOI VLT LDMOS considering electrical-thermal couple effects

Varied Lateral Thickness (VLT) technology is a novel voltage-sustaining technology which has been developed recently. This paper focuses on the static and dynamic operation performance of SOI LDMOS using the VLT technology. Firstly, the VLT LDMOS is optimized by using the TCAD tool to maximize the off-state breakdown voltage. The results show that the drift doping concentration and the breakdown voltage of the VLT device increase by 59.2% and 11.8% compared with the conventional REduce SURface Field (RESURF) LDMOS, respectively. Secondly, the static I-V characteristic and the dynamic I-V characteristic of the both devices are investigated in detail. The carrier mobility and the impact ionization are analyzed to explore the physical mechanism of the electro-thermal couple effects under the continual and pulse biased voltages. The results show that the VLT LDMOS has higher breakdown voltage, larger operating current and improved static/dynamic Safe Operating Area (SOA).