High Efficiency 1700V 4H-SiC UMOSFET with Local Floating Superjunction

This paper introduces an improved efficiency 4H-SiC MOSFET structure. Compared to conventional p-shielding UMOSFETs, the proposed 4H-SiC UMOSFET with a local floating superjunction (LFS-UMOSFET) can reduce the on-resistance while maintaining a 1700 V breakdown voltage. In addition, it shows an improvement in switching loss. To verify the improvement, the conventional p-shielding UMOSFET and the proposed UMOSFET are modeled for energy loss. The simple buck convertor is used to measure power loss and junction temperature. The structure is based on a conventional trench bottom p-shielding UMOSFET with the superjunction structure located beneath the p-shielding. It was optimized for various variables to improve the on-resistance while maintaining the breakdown voltage. The proposed UMOSFET showed a 48% reduction in the specific on-resistance and a 20.6% reduction in the switching loss. Electrical characteristics is simulated by sentaurus TCAD, and modeling and circuit simulation is simulated by PSIM, a power circuit simulator.