Effect of P+ Source Pattern in 4H-SiC Trench-Gate MOSFETs on Low Specific On-Resistance

Novel 1.7-kV 4H-SiC trench-gate MOSFETs (TMOSFETs) with a grid pattern and a smaller specific on-resistance are proposed and demonstrated via numerical simulations. The proposed TMOSFETs provide a reduced cell pitch compared with TMOSFETs with square and stripe patterns. Although TMOSFETs with a grid pattern reduce the channel area by approximately 10%, the cell density is increased by approximately 35%. Consequently, the specific on-resistance of the grid pattern is less than that of the square and stripe patterns. The forward blocking characteristics of the grid pattern are increased by the reduced impact ionization rate at the P/N junction. As a result, the figure-of-merit (FOM) of the grid pattern is increased by approximately 33%.