Reliability studies of SiC vertical power MOSFETs

Power metal-oxide-semiconductor field-effect transistors (MOSFETs) experience conditions of high field during normal operation, with high MOS gate oxide field in the on-state, and high drift and termination fields in the blocking state. Moreover, silicon carbide devices typically experience higher fields than comparable Si devices due to channel and drift property differences. SiC MOSFET threshold voltage stability and gate oxide lifetime under high gate oxide field are observed to follow the same functional form as Si devices. SiC MOSFETs demonstrate intrinsic oxide lifetime greater than 10 ⁷ hrs in time-dependent dielectric breakdown (TDDB) testing. Accelerated high-temperature reverse-bias (HTRB) testing above the rated voltage reveals similarly long lifetime under high drift fields. The device failure rate due to terrestrial neutron single-event burnout (SEB) is shown to be comparable or superior to that of Si devices. Results demonstrate the reliability of SiC MOSFETs under high-field operation.