Methodology of Failure Mode Analysis in Short-Circuit State of SiC MOSFETs by Electro-Thermal-Mechanical TCAD Simulations

The mechanical short-circuit failure mode of 1.2 kV class SiC MOSFETs was investigated by experiment and electro-thermal-mechanical technology computer-aided design (TCAD) simulation. In this work, the details of the simulation procedure are described. TCAD simulations provide a powerful means to address the mechanical failure of such devices, and indicates that high-level stress concentrates at the gate dielectric layer because of the large thermal expansion coefficient of the source metal. Further, a low mechanical stress design for short-circuit in SiC MOSFETs is proposed by using low thermal expansion metal such as copper as the source electrodes.