Effect of short-circuit degradation on the remaining useful lifetime of SiC MOSFETs and its failure analysis

When the SiC MOSFET works in the normal operating conditions, its remaining useful lifetime used to be estimated based on the monitored parameters and the lifetime model derived from accelerated tests. In this case, the degradation caused by abnormal events has not been considered. Therefore, it makes sense to investigate the effect of short-circuit degradation on the remaining useful lifetime of SiC MOSFETs. A different number of repetitive short-circuit events have been introduced into the accelerated power cycling tests to assess the impact. The experimental results indicate a gate degradation with the increasing number of short-circuit repetitions, which leads to higher conduction loss and earlier failure. Further failure analysis is achieved by performing lock-in thermography, scanning electron microscopy, and focused ion beam.