Patent ID: 6071793
Filing Date: 2000-06-06
Classification: H01L

Abstract:
A method for forming a field oxide isolation region on a silicon substrate comprising the steps of:(a) providing a silicon substrate;(b) forming a pad oxide over said silicon substrate;(c) forming a silicon nitride layer of a first thickness over said pad oxide;(d) patterning and partially etching said silicon nitride layer with an anisotropic etching technique, thereby forming a opening and a second thickness of said silicon nitride layer in said opening;(e) depositing a layer of spacer material on said silicon substrate;(f) etching said layer of spacer material thereby forming spacers in the periphery of said opening;(g) simultaneously etching said silicon nitride layer and said spacers with an anisotropic etching technique, whereby a tapered silicon nitride foot is formed under said spacers; and(h) subjecting said silicon substrate to thermal oxidation, thereby forming said a field oxide isolation region.