Analysis of Thermal Concentration Failure in Unclamped Inductive Switching Based on Three-Dimensional Electro-Thermal Simulation With On-Chip Variation

The analysis of failure development in unclamped inductive switching (UIS) is one of the most important aspects for improving the robustness of power MOSFETs. The observation of the failed chip surface revealed that the UIS failure occurs in a small area. No conventional simulation method has successfully reproduced this confinement because spatial variation of current and temperature on the chips have been ignored. In this study, we propose a three dimensional electro-thermal simulation method for UIS failure analysis. Our simulation result has shown significant current concentration due to the positive interdependence between local temperature and drain current in the intrinsic operation. In our simulation, the temperature of the failure region reaches over 4600 K.