Impact of grounding the bottom oxide protection layer on the short-circuit ruggedness of 4H-SiC trench MOSFETs

This paper investigates the effects of grounding the p-type gate-oxide protection layer called bottom p-well (BPW) of a trench-gate SiC-MOSFET on the short-circuit ruggedness of the device. The BPW is grounded by forming ground contacts in various cell layouts, and the layout of the contact cells is found to be a significant factor that determines the short-circuit safe operation area (SCSOA) of a device. By grounding the BPW in an optimized cell layout, an SCSOA of over 10 μs is obtained at room temperature. Further investigation revealed that minimizing the distance between the ground contacts for the BPW is a key to developing a highly-robust, high-performance power device.