First Demonstration of Short-Circuit Capability for a 1.2 kV SiC SWITCH-MOS

Abstract

In this paper, the authors report a unique short circuit failure mechanism of a 1.2 kV silicon carbide (SiC) SBD-wall-integrated trench MOSFET (SWITCH-MOS), using numerical simulations and experimental validation. When the Schottky barrier height in the SWITCH-MOS was set at 1.20 eV, the short-circuit withstand time was roughly half that of a conventional SiC trench MOSFET. This is because, in the SWITCH-MOS, the thermionic-field emission electrons passing through the embedded SBD continue flowing into the high electric field in the n− drift region, even after the gate is turned off. This causes heat generation in the device, resulting in thermal runaway. Using a novel methodology for improving the short-circuit capability, it was confirmed that metal with a high Schottky barrier height of 1.75 eV can significantly improve the SWITCH-MOS short-circuit capability, making it comparable to that of conventional SiC trench MOSFETs, and suggesting SWITCH-MOS devices may be superior power devices for use in high frequency inverters.