Ultralow Angle Bevel-Etched Junction Termination Extension for High Voltage SiC Power Devices

The ultralow angle (ULA) bevel-etched (BE) junction termination extension (JTE) for high voltage SiC power devices is proposed and investigated in this paper. The local bevel alleviates the electric field (E-field) crowding at each step corner and thus allows an increased breakdown voltage (BV) and a wide process tolerance. With a small bevel angle of 2°, the 1-step ULA-BE JTE reaches over 90% of the ideal BV of parallel plane junction and exhibits the BV 3kV higher than that of conventional (Con.) vertically-etched (VE) JTE. The 3-step ULABE JTE delivers 2.7X improvement in the etching depth window compared with Con. VE JTE. We have performed the experiment of 1-step etch of the 4H-SiC ULA-BE JTE. The etching depth of 1.67 µm with the lateral distance of 50.2 µm is obtained, demonstrating the corresponding bevel angle of 1.9°, which is a superior JTE solution for SiC high voltage power devices.