Trench Multiple Floating Limiting Rings Termination for 4H-SiC High-Voltage Devices

Abstract

A junction termination method adopting heavily doped p-well rings with a shallow trench for each ring, named as a trench multiple floating limiting rings (TMFLRs), is analyzed and fabricated without any additional process in 4H-SiC junction barrier Schottky diode. A breakdown voltage of 6.7 kV is achieved using TMFLRs structure on an epitaxial layer with thickness of 50 $\mu \text{m}$ , while the breakdown voltage of the conventional planar FLRs structure with the same termination area is only 5.7 kV. The experimental result has demonstrated that the TMFLRs termination structure yields about 90% of the parallel plane breakdown voltage. In addition, the simulation results show that the TMFLRs make the bulk peak electric field ( $E_{p,\text {bulk}})$ reduce and move away from the device surface, successfully making the interface peak electric field ( $E_{p,\text {interface}})$ decrease by about 30% compared with a conventional planar FLRs structure when same reverse voltages applied.