Multiple UIS Ruggedness of 1200V Asymmetric Trench SiC MOSFETs

In this paper, 1200V commercial asymmetric trench silicon carbide (SiC) metal-oxide-semiconductor-field-effect-transistors (MOSFETs) are investigated by experiment under multiple unclamped inductive switching (UIS) events. The degradation of electrical characteristics and failure mode are evaluated under various avalanche energy ratio. Meanwhile, cross-section of damage point of failure device is identified using Focus Ion Beam (FIB). Under low energy ratio condition, the on-resistance (R
on
) increases ~11% whereas the threshold voltage (V
th
) remains almost constant, which indicates that thermal fatigue is main reason of failure. Under high energy ratio condition, burn out of field oxide and metal Al is observed, which is caused by high thermal stress.