Short-Circuit Robustness of SiC Trench MOSFETs

Abstract

An investigation into the robustness of 1200-V/80-mΩ commercial trench-gate MOSFETs reveals that the critical energy for failure during short-circuit operation is reached in shorter times in comparison to similarly rated planar DMOSFETs under similar stress conditions. This critical energy for trench devices was estimated to be between 615 mJ to 660 mJ depending on the gate-drive voltage. These values are considerably smaller when compared to DMOSFETs from the same manufacturer. In comparison to planar designs, trench devices can have lower losses, and manufactured with much smaller chip size for the same device rating. As a result, higher power density, improved efficiency, lower chip costs, and higher yields for trench designs are possible, but these enhancements are offset by a reduction in short-circuit capability. The critical short-circuit time for a 600-V bus voltage is shown to be dependent on gate-drive voltage magnitude, with higher gate voltages leading to increased peak short-circuit current, higher power dissipation, and reduced short-circuit capability.