Trench Field Plate Engineering for High Efficient Edge Termination of 1200 V-class SiC Devices

Abstract

Trench field plate engineering for high efficient edge termination of 1200 V-class SiC devices is proposed and experimentally demonstrated. The structure features a deep trench filled with benzocyclobutene (BCB) dielectric, and a U-shaped field plate is incorporated in the deep trench. The deep trench extends through the epitaxial layer into the substrate to eliminate the negative effects of the microtrench on breakdown voltage. The U-shaped field plate modulates the electric field distribution to prevent premature breakdown at the interface between the P-base and trench. The SiC outside the trench is diced away to reduce the peak electric field at the edge of the field plate by spreading the electrostatic potential both horizontally and vertically. The trench field plate edge termination structure is implemented by integrating with a PiN diode. Experimental results show that the structure achieves a breakdown voltage of 1380 V, which is approximately 100% of the ideal planar junction breakdown voltage of the PiN diode. The fabricated edge termination structure has an ultra-short width of $33 \boldsymbol{\mu} \mathbf{m}$ . Compared with conventional junction termination extension structures used in 1200 V-class SiC devices, the width of the proposed structure is approximately 75% shorter.