Evolution of Electrical and Thermal Ageing Parameters in SiC MOSFETs Under Power Cycling

ABSTRACT

Silicon carbide (SiC) power MOSFETs are gaining significant attention in various industries due to their superior performance in comparison to silicon‐based MOSFETs. The reliability of discrete SiC power MOSFETs remains less explored compared to the SiC power modules. This paper investigates the reliability of the SiC power MOSFETs through DC power cycling, using TO‐247 packaged devices as the representative for the discrete devices. The evolution of electrical ( R _ds‐on , V _th ) and thermal ( R _th‐jc ) parameters for four Wolfspeed SiC MOSFETs (C3M0016120D) with gradual ageing is tracked till their end of life (EOL) is reached. After the EOL is reached, non‐destructive X‐ray computed tomography is used to correlate the physical changes within the package to the changes observed in the electrical and thermal properties. Experimental results showed that R _ds‐on , V _th , R _th‐jc , and junction temperature can be used for the condition monitoring of SiC MOSFETs in reliability‐critical applications like aerospace and electric vehicles, R _ds‐on demonstrating the highest sensitivity and practical utility as a condition‐monitoring parameter under the specific test conditions, package structure, and dominant failure mechanisms investigated in this work. The degradation trends are driven by electro‐thermal stress on aluminium bondwires and the die‐attach solder layer.