Influence of high temperature reliability test on threshold voltage and on resistance of 1200V SiC MOSFET

Although SiC MOSFET has obvious advantages over silicon-based devices in high-temperature applications, its performance still does not reach the theoretical level, especially in high-temperature reliability. Due to the influence of gate oxygen, interface contact and other process problems, the stable use of devices in high temperature, high voltage and high current environment is limited. The single-chip 1200V20A SiC MOSFET devices packaged TO247 form produced by our company were selected to carry out the HTRB and HTGB reliability tests. The changes of threshold voltage and on resistance of the devices after 168 hours of high-temperature reliability test were studied, and the variation trend of device parameter-dispersion was analyzed. Finally, it is concluded that the high-temperature reliability test has the greater effect on the threshold voltage. The primary and secondary effects of the high temperature gate bias (HTGB) test and high temperature reverse bias (HTRB) test on parameters and dispersion were compared. The HTGB test increases the threshold voltage, but the HTRB test reduces the threshold voltage more greatly. Therefore, the threshold voltage of the device after the HTRB test and HTGB test is reduced. Differently, the high temperature reliability test has the greater effect on the dispersion of on resistance, which increases the variation coefficient. This is mainly due to the more serious influence of HTRB test.