Investigation of Safe Operating Area on 4H-SiC 600V VDMOSFET with TLP and UIS Test Methods

In high-power MOSFET, during the transient switching moment from on-state to off-state, it would suffer high VDS voltage and high IDS current in a short period at the same time. Hence, safe operating area (SOA) is always an essential characteristic that must be considered when power modules were designed. It this study, two methods (TLP and UIS) to characterize SOA of a 600V vertical double-implanted MOSFET (VDMOSFET) fabricated by SiC process were performed. From the results of TLP measurement, it was found that the triggered voltage (V_t1) decreased with the increment of gate bias (V_GS). The snapback phenomenon was also observed in the TLP-measured I_ds-V_ds curve. To acquire the stable holding characteristic after VDMOSFET breakdown during UIS testing, a current-limiting resistance was used to prevent the device from burning out directly. Nevertheless, even though the device size of VDMOSFET was large enough (around 180kμm), it would still be burned out during the UIS testing with Vcc bias of only several hundred volts.