Study of a SiC Trench MOSFET Edge-Termination Structure with a Bottom Protection Well for a High Breakdown Voltage

Abstract

A novel edge-termination structure for a SiC trench metal–oxide semiconductor field-effect transistor (MOSFET) power device is proposed. The key feature of the proposed structure is a periodically formed SiC trench with a bottom protection well (BPW) implantation region. The trench can be filled with oxide or gate materials. Indeed, it has almost the same cross-sectional structure as the active region of a SiC trench MOSFET. Therefore, there is little or no additional process loads. A conventional floating field ring (FFR) structure utilizes the spreading of the electric field in the periodically depleted surface region formed between a heavily doped equipotential region. On the other hand, in the trenched ring structure, an additional quasi-equipotential region is provided by the BPW region, which enables deeper and wider field-spreading profiles, and less field crowding at the edge region. The two-dimensional Technology Computer Aided Design (2D-TCAD) simulation results show that the proposed trenched ring-edge termination structures have an improved breakdown voltage compared to the conventional floating field ring structure.

Edge Terminations for 4H-SiC Power Devices: A Critical Issue

“…On the other hand, the recent availability of SiC trench devices also required adaptation of edge termination. In this sense, 3D edge termination like trench guard rings terminations have been recently proposed for SiC devices [8]. This termination configuration has shown to be efficient in Silicon technologies.…”