A Novel Vertical Field Plate Lateral Device With Ultralow Specific On-Resistance

摘要

A novel vertical field plate (VFP) lateral device with ultralow specific on-resistance $(R_{{rm ON},{rm sp}})$ is proposed in this paper. The VFP surrounded by oxide is inserted in the bulk of the drift region. Compared to the surface local depletion of the conventional lateral field plate (LFP), the depletion layer of the VFP expands to the bulk of the drift region, which enhances the bulk electric field. Therefore, ultralow $R_{{rm ON},{rm sp}}$ is realized in the VFP device due to high drift-region doping $(N_{d})$ and short cell pitch. An analytical FP model is developed to describe the behavior of the VFP, in which the breakdown voltage (BV) and $N_{d}$ are found to be proportional to the FP factor $k$. Then the uniform-doped VFP laterally diffused MOSs and the step-doped VFP laterally diffused MOS are proposed. The optimized device exhibits a BV of 945 V and a $R_{{rm ON},{rm sp}}$ of 34 ${rm m}Omegacdot{rm cm}^{2}$ which are superior to those of similar devices and the silicon limit.