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

The temperature sensitive electrical parameters (TSEPs) have been used in SiC MOSFETs $T_j$ measurement for over-temperature protection and condition-monitoring. However, the device aging can affect the TSEPs thus leads to false measurement. In this paper, the aging's impact on various TSEPs are comprehensively investigated. Specifically, utilizing the DC power cycling test, both the device and package degradations 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. From the experimental results, it is found that both the static and switching-related TSEPs can be affected by the aging, and each TSEP is impacted to different extent. The gate oxide degradation induced threshold voltage shift and transconductance change mainly contribute to the parameter changes. Meanwhile, the package degradation can also affect some static TSEPs, especially at the high current levels. In addition, it is observed that some of the switching-related TSEPs like turn-on di/dt and turn-off delay time are changed differently for devices with distinct structures. Based on the evaluation results, the temperature measurement errors due to aging are summarized. It is concluded that the aging's effect on TSEPs needs to be considered for accurate $T_j$ measurement.