A trench beside field limiting rings terminal for improved 4H-SiC junction barrier Schottky diodes: Proposal and investigation

Abstract

A novel trench beside field limiting rings (TBFLR) terminal for 4H-SiC junction barrier Schottky (JBS) diodes is introduced and analyzed by technical computer-aided design (TCAD) simulation, addressing the electric field crowding challenge in high-voltage applications. The design parameters of the devices are optimized by striking a balance between forward and reverse electrical performances. Comparative analysis reveals that TBFLR significantly reduces the surface peak electric field, making it particularly advantageous for shallow-junction devices. Conversely, trench inside FLR (TFLR) is suited for deep-junction applications due to its deeper junction and higher breakdown voltage (BV). The TBFLR design excels with its low on-resistance and compact terminal length, especially in ultra-high voltage (>6500 V) scenarios, achieving target BV with fewer rings and reduced terminal area. Notably, the TBFLR has a terminal efficiency of at least 80 % while keeping trench depth within the 60 % range of the junction depth. Furthermore, an enhanced computational model is proposed, which introduces harmonic parameters to quantify the role of the trench in FLR, and this adaptable model can be effectively extended to the composite renewal of FLR structures. This work provides a distinct application strategy for trench-based FLR structures, significantly broadening the scope of terminal design possibilities.