Power Cycling Tests in High Temperature Conditions of SiC-MOSFET Power Modules and Ageing Assessment

Silicon carbide (SiC) MOSFETs power modules are very attractive devices. Despite technological progress, reliability remains an issue and reliability tests must be conducted to introduce more widely these devices into power systems. Because of trapping/de-trapping phenomena at the SiC/SiO2 interface that lead to the shift of threshold voltage, test protocols based on silicon components cannot be used as is, especially in high temperature conditions. Using high temperature SiC MOSFET power modules, we highlight the main experimental difficulties to perform power cycling tests (PCTs). As these reversible physical mechanisms preclude the use of temperature sensitive parameters (TSEP) for junction temperature measurements, we set up fiber temperature sensors for this purpose. Moreover, these degradation phenomena lead to difficulties in both controlling the test conditions and seeking for reliable aging indicator parameters. Finally, various results of power cycling tests with different gate bias conditions at high temperature are discussed in order to propose a test protocol.