A simple process for breakdown voltage improvement in planar junction of DMOS devices.

Argon ion implantation was used to create a damaged surface layer on field oxide, then the subsequent oxide etching created a tapered oxide transition from thin oxide to thick field oxide. This structure effectively improves the breakdown voltage of the planar junction of a DMOS device which makes use of the poly field plate to enhance the breakdown voltage. The process is simple, reproducible, and introduces no new mask steps into the BCDMOS technology.