Robust Trench Buried-Guard-Ring-Based Termination for Charge Balanced Devices

A major limitation on the performance of high-voltage power semiconductor is the edge termination of the device. It is critical to maintain the breakdown voltage of the device without compromising the reliability of the device by controlling the surface electric field. A good termination structure is critical to the reliability of the power semiconductor device. The proposed termination uses a novel trench MOS with buried guard ring structure to completely eliminate high surface electric field in the silicon region of the termination. The proposed termination scheme was applied toward a 1350-V fast recovery diode and showed excellent results. It achieved 98% of parallel plane breakdown voltage, with low leakage and no shifts after high-temperature reverse bias testing due to mobile ion contamination from packaging mold compound.