This paper presents a comprehensive study on single- and repetitive-frequency UIS characteristics of 1200 V asymmetric (AT) and double trench silicon carbide (DT-SiC) metal-oxide-semiconductor eld-eect transistors (MOSFETs) and their electrical degradation under electrical–thermal working conditions, investigated through experiment and simulation verication. Because their structure is dierent, the failure mechanisms are dierent. Comparatively, the gate oxide of a DTMOSFET is more easily damaged than an AT-MOSFET because the hot carriers are injected into the oxide. The parameters’ degradation under repetitive UIS stress also requires analysis. The variations in the measured parameters are recorded to evaluate typical electrical features of device failure. Furthermore, TCAD simulation is used to reveal the electrothermal stress inside the device during avalanche. Additionally, failed devices are decapsulated to verify the location of the failure point. Finally, a new type of stepped-oxide vertical power DT MOSFET with P-type shielding and current spread layers, along with its feasible process ow, is proposed for the improvement of gate dielectric reliability.
Loading....