Accelerated Testing of SiC Power Devices

Power metal-oxide-semiconductor field-effect transistors (MOSFETs) experience conditions of high field during normal operation. During switching conditions, unexpected transient events may occur which force devices into avalanche or short circuit conditions. Moreover, silicon carbide devices typically experience higher fields in the gate oxide and drift regions than comparable Si devices due to channel and drift property differences. A summary of 4H-SiC MOSFET reliability and ruggedness test results are reported here. Reliability tests under high field conditions: positive-bias and negative-bias temperature instability (PBTI, NBTI) to examine threshold stability; time-dependent dielectric breakdown (TDDB) for gate oxide lifetime extrapolation; high-temperature reverse bias (HTRB); and HTRB testing under high neutron flux to determine terrestrial neutron single-event burnout (SEB) rates. High-power ruggedness evaluation is presented for SiC MOSFETs under forced avalanche conditions (unclamped inductive switching (UIS)) and under short-circuit operation to bound device safe operating areas. Overall results demonstrate the intrinsic reliability of SiC MOSFETs.