Evaluation of 1.2-kV Rated SiC Trench MOSFETs Under High-Voltage Switching Impulses

In this work, three types of $1.2-\mathrm{kV}$ rated commercial SiC trench MOSFETs were evaluated under repetitive switching impulses at $80 \%$ of their breakdown voltage. The experiment results indicate that the reliability of the trench corner of DT1-MOS is inferior compared to DT2MOS and AT-MOS. After $9 \times 10^{6}$ impulses, significant gate leakage current was detected in DT1-MOS, while this degradation was absent in both DT2-MOS and AT-MOS. Notably, the degradation of gate oxide in the channel region appeared unaffected by drain-source voltage ($V_{\mathrm{ds}}$) stress. The observed positive shift in threshold voltage across all three types of devices is attributed to gate bias stress, which subsequently leads to an increase in channel resistance. Additionally, a negative shift in on-state resistance was recorded in DT1-MOS and DT2-MOS, likely due to hot holes injection into the gate oxide at the trench bottom.