VDS and VGS Depolarization Effect on SiC MOSFET Short-Circuit Withstand Capability Considering Partial Safe Failure-Mode

International audience; This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution.This paper presents a detailed analysis of 1200 V Silicon Carbide (SiC) power MOSFETexhibiting different short-circuit failure mechanisms and improvement in reliability by VDS andVGS depolarization. The device robustness has undergone an incremental pulse under differentdensity decreasing; either drain-source voltage or gate-driver voltage. Unlike silicon device, the SiCMOSFET failure mechanism firstly displays specific gradual gate-cracks mechanism and progressivegate-damage accumulations greater than 4 µs/9 J·cm−2. Secondly, a classical drain-source thermalrunaway appears, as for silicon devices, in a time greater than 9 µs. Correlations with short-circuitenergy measurements and temperature simulations are investigated. It is shown that the firstmechanism is an incremental soft gate-failure-mode which can be easily used to detect and protectthe device by a direct feedback on the gate-driver. Furthermore, it is highlighted that this newmechanism can be sufficiently consolidated to avoid the second drain-source mechanism which is ahard-failure-mode. For this purpose, it is proposed to sufficiently depolarize the on-state gate-drivevoltage to reduce the chip heating-rate and thus to decouple the failure modes. The device is muchmore robust with a short-circuit withstand time higher than 10 µs, as in silicon, no risk of thermalrunaway and with an acceptable penalty on RDS-ON.