Classification of Commercial SiC-MOSFETs Based on Time-Dependent Gate-current Characteristics

SiC-MOSFETs with high reliability have been desired for electric vehicles. We classify commercial SiC-MOSFETs into “heavily nitrided” and “lightly nitrided” based on time-dependent gate-current characteristics of fabricated devices. In “heavily nitrided” devices for higher mobility, high-voltage gate pulse for screening of B-mode (extrinsic defects) causes hole-trapping near the SiO2/SiC interface through impact ionization. This phenomenon leads to an increase in gate current as well as a negative shift of threshold voltage. Moreover, this is enhanced at low temperatures (-60, 25°C). Thus, high-temperature (200°C) screening is preferable. In addition, the relation between Weibull slopes for time-to-breakdown and charge-to-breakdown is closely examined.