Comparative Evaluation of the Short circuit Capability of SiC Planar and Trench Power MOSFET

In this paper, the short circuit robustness of SiC trench MOSFETs is analyzed and compared with SiC planar MOSFETs. Thermal simulation during short circuit operations are studied in this work. A short circuit test bench is constructed for tests of MOSFETs. Commercially available 650V SiC trench MOSFETs and planar MOSFETs with similar rated voltage and on-state resistance are tested. From experimental results, the 650V SiC trench MOSFET fails much earlier than 650V SiC Planar MOSFET. The test results are analyzed with aid of one dimensional finite element thermal model. The model is constructed based on structure parameters. According to the thermal model, the dominant factor of a weaker short circuit robustness of SiC trench MOSFET is the highly concentrated distribution of electric field as well as intense current density during short circuit operation.