Degradation Investigations on Asymmetric Trench SiC Power MOSFETs Under Repetitive Unclamped Inductive Switching Stress

Abstract

In this paper, the degradation phenomena and mechanism of the asymmetric trench Silicon carbide (SiC) power metal-oxide semiconductor field-effect transistor (MOSFET) under repetitive unclamped inductive switching (UIS) stress are investigated in details. The trench corner is verified to be the mainly degraded region by Silvaco TCAD simulations and experimental measurements. It is demonstrated that the dominant degradation mechanism is the injection of hot holes into the gate oxide at the trench corner. After enduring 300k UIS stress cycles, the threshold voltage (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> ) decreases by nearly 1V while the gate-drain capacitance (C <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">gd</sub> ) increases seriously by 46.2%, leading to the degradations in switching properties. Furthermore, the R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</sub> is decreased by 7.2%.