Evaluation of Aging's Effect on Temperature-Sensitive Electrical Parameters in SiC MOSFETS

The temperature-sensitive electrical parameters (TSEPs) have been used in silicon carbide (SiC) MOSFETS junction temperature measurement for over-temperature protection and condition monitoring. However, the device aging can affect the TSEPs and thus leads to false T-j measurement. In this article, the aging's impacts on various TSEPs are comprehensively investigated. Specifically, utilizing the dc power cycling test, both the gate oxide instability and package degradation are considered. Then the commercial devices with different structures are aged, and their temperature-dependent static and switching characteristics are evaluated at different aging cycles. Both the positive gate bias-induced threshold voltage shift and package degradation are observed, and their impacts on each TSEP are evaluated independently. Based on the evaluation results at various operating conditions, the temperature measurement errors due to different aging mechanisms are well summarized for each TSEP. From the dc power cycling test result, the package degradation's impact on TSEPs is found to be more significant than the gate oxide instability. It is pointed out that the aging's effect on TSEPs is an important factor that needs to be considered for accurate T-j measurement in SiC MOSFETS.