Comparative Investigation on Aging Precursor and Failure Mechanism of Commercial SiC MOSFETs Under Different Power Cycling Conduction Modes

Power cycling test (PCT) is an effective method to evaluate the SiCmosfets' long-term reliability, including lifetime and degradation mechanisms. Some of the aging precursors of PCT have been identified in the previous literature. But when multiple failure mechanisms compete with each other, the individual precursors are nullified. Although PCT is mainly used to evaluate the package reliability, there are still unresolved problems due to the gate oxide reliability of SiCmosfet, and the repeated gate stress of the power cycling has different effects on the devices with different gate structures. This article presents a comprehensive investigation of the aging precursors and failure mechanism of three typical commercial SiCmosfets with different gate structures through PCTs under two different conduction modes. Degradation-related essential precursors and possible causes behind them are discussed. The failure mechanisms and correlation with the degradation state of different devices are studied in depth. In addition, the effects of PCT under different conduction modes on failure mechanism and lifetime have been investigated.