Microstructural Evolution of Gate Oxide in SiC Power MOSFETs Under Heavy-Ion Irradiation

Maintaining the robustness of the gate oxide is a prerequisite for the on-orbit application of SiC MOSFETs. Recent research has demonstrated that the oxide undergoes premature breakdown within the operating voltage range after heavy ion irradiation, which is attributed to the activation of ion-induced gate latent damages (LDs) under gate post-irradiation gate stress (PIGS). However, the specific activation processes of LDs and oxide failure mechanism are not well understood. This study indicates that the dielectric breakdown induced epitaxy (DBIE) and thermal runaway effects are the dominant mechanisms when oxide rupture occurs, characterized by a step-like increase in gate leakage current during PIGS test. The failure analysis further confirmed the formation of DBIE hillock and percolation path. The results suggest that more attention should be paid to the gate oxide reliability before SiC MOSFETs could replace their Si-based counterparts in aerospace applications.