Trench schottky barrier diode with differential oxide thickness

Abstract

A fabrication process for a trench Schottky diode with differential oxide thickness within the trenches includes forming a first nitride layer on a substrate surface and subsequently forming a plurality of trenches in the substrate including, possibly, a termination trench. Following a sacrificial oxide layer formation and removal, sidewall and bottom surfaces of the trenches are oxidized. A second nitride layer is then applied to the substrate and etched such that the second nitride layer covers the oxide layer on the trench sidewalls but exposes the oxide layer on the trench bottom surfaces. The trench bottom surfaces are then re-oxidized and the remaining second nitride layer then removed from the sidewalls, resulting in an oxide layer of varying thickness being formed on the sidewall and bottom surfaces of each trench. The trenches are then filled with a P type polysilicon, the first nitride layer removed, and a Schottky barrier metal applied to the substrate surface.