A novel structure of SOI lateral MOSFET with vertical field plate

A new high voltage silicon-on-insulator (SOI) lateral MOSFET with an enhanced breakdown voltage (BV) and a reduced specific on-resistance (R_{on, sp}) is presented. The structure features a drain vertical field plate and a gate vertical field plate (DTDP SOI). The assisted depletion effect of the dual vertical field plate brings two benefits. Firstly, the distribution of electric field in the drift region is modulated and the average electric field strength is enhanced, resulting in the improvement in BV. Secondly, the optimal doping concentration of drift region is significantly increased, which reduces the R_on,sp significantly by reducing the resistance of the drift region in the on-state. The mechanism of the dual vertical field plate is analyzed and the characteristics of BV and R_on,sp are discussed. It is shown that the BV of the DTDP SOI increases from 345 V of the dual trench lateral MOSFET and 152 V of the conventional lateral MOSFET to 485 V, and the highest figure of merit is obtained for the DTDP SOI in the three structures due to its low R_{on, sp}.