The Novel Junction Termination Method Employing Shallow Trench

Abstract

We propose a novel junction termination method employing shallow silicon trenches filled with silicon dioxide, which decreases the junction termination radius by 23% while maintaining the identical breakdown voltage. The shallow silicon trenches filled with silicon dioxide and P+ FLRs (Field Limiting Rings) in the proposed structure reduced the electric field concentration in the P+ cathode due to the low dielectric constant of the silicon dioxide. We fabricated the proposed structure in silicon wafers and measured its breakdown voltage. The proposed junction termination method does not require any complex fabrication process such as a deep silicon trench or silicon bevel edge etching. The junction termination radius of the proposed structure employing three trenches was decreased by 23% compared with that of the conventional FLR employing three P+ FLRs. The breakdown voltage of the proposed structure with four trenches was 664V, which is 86% of the ideal parallel-plane breakdown voltage.