An Improved Junction Termination Design Employing Shallow Trenches and Field Limiting Rings for Power Devices

Abstract

A new junction termination method employing shallow trenches filled with silicon dioxide and field limiting rings (FLRs) for 1200 V power device applications is proposed to decrease the junction termination area without sacrificing the breakdown voltage and any additional fabrication processes. The proposed structure was analyzed and verified by numerical simulations and experiments. The two-dimensional numerical simulation results show that two electric field peaks between the field limiting rings appear in the proposed structure due to the shallow trench filled with silicon dioxide while the conventional FLR structure shows a single electric field peak between the field limiting rings. The proposed structure achieves a uniform electric field distribution and increases a breakdown voltage. The junction termination area of the proposed structure is decreased at the same breakdown voltage due to the low dielectric constant of the silicon dioxide in the trench. The experimental results show that the junction termination length of the proposed structure is 15–21% lower than that of the conventional FLR. The proposed structure achieves the high breakdown voltage, which is 80% of the ideal parallel-plane junction breakdown voltage.