Investigation into the Aging Mechanisms of a SiC-Based Power MOSFET by Thermal and Thermomechanical Analysis

The use of wide-bandgap semiconductor-based transistors has become essential in recent years for the development of new systems for sustainable mobility and, more generally, for energy conversion. In this frame, silicon carbide-based power MOSFETs are currently the most promising devices, as they enable the simultaneous management of high voltages and high currents. During the switching phases, the device experiences current pulses, which, due to Joule heating, lead to thermomechanical expansion processes caused by the generated heat. This process represents one of the main aging mechanisms for this class of devices, whose failure mechanisms may significantly differ from that of silicon-based devices. This work proposes an analysis protocol to thermally and thermomechanically characterize a commercially available SiC power MOSFET. To this end, the device was subjected to periodic stress cycles to realistically simulate its aging process as closely as possible. To assess the device's health status, its dynamic ON resistance, measured during a test pulse, was monitored. This choice is motivated by the possibility of tracking this parameter during normal system operation, thus enabling a possible estimation of the device's remaining lifetime on the field.