Patent ID: 6090685
Filing Date: 2000-07-18
Classification: H01L,Y10S

Abstract:
A method of forming a semiconductor structure comprising:forming a pad oxide layer upon a semiconductor substrate;forming an oxidation barrier layer upon said pad oxide layer;selectively removing portions of said oxidation barrier layer to form a lateral surface thereon and to expose selected areas of said pad oxide layer;forming a field oxide in the exposed selected areas of said pad oxide layer, said field oxide including a first portion having about the thickness of said pad oxide layer that touches said lateral surface of said oxidation barrier layer;selectively removing said first portion of said field oxide at an edge thereof to expose a portion of said semiconductor substrate;forming a trench within said semiconductor substrate in contact with and beneath the exposed portion of said semiconductor substrate, said trench being situated between said oxidation barrier layer and said field oxide;forming a cover layer, composed of a material selected from a group consisting of oxide and nitride, within said trench and upon said oxidation barrier:selectively removing said cover layer to form a spacer upon said lateral surface of said oxidation barrier layer; andenlarging said field oxide.