Gate failure process and mechanism of SiC MOSFETs under the effect of multiphysics field during short-circuit transients

Robust short-circuit (SC) withstand capability is crucial for the practical applications of SiC MOSFETs. The failure mechanisms of SiC MOSFETs vary depending on the applied conditions. In this paper, the SC failure process of 600 V SiC MOSFETs at a low gate voltage is investigated, and an unreported failure mechanism is uncovered: a cascading failure mechanism initiated by gate oxide (GOX) rupture, followed by polysilicon (Poly) thermal expansion, and culminating in Pre-Metal Dielectric (PMD) fracture. Electro-thermal-mechanical simulations establish that defect generation and effective thickness thinning likely precipitate GOX breakdown, and the degradation of Poly and PMD stems from high temperature and thermomechanical stress. This failure frequently occurs under conditions of either a thin gate oxide or poor gate oxide quality. Experiments show that improving GOX quality effectively increases the SC time.