Patent ID: 6238999
Filing Date: 2001-05-29
Classification: H01L

Abstract:
An isolation region forming method comprising:forming a silicon nitride layer over a substrate;forming a masking layer over the silicon nitride layer;forming a pattern of openings extending through the masking layer to the silicon nitride layer;extending the openings through the silicon nitride layer to the underlying substrate with a first etch, the silicon nitride layer comprising edge regions proximate the openings and having a central region between the edge regions;extending the openings into the underlying substrate with a second etch, the second etch forming a polymer over the edge regions;after extending the openings into the underlying substrate, exposing the silicon nitride layer and masking layer to dry etching conditions to remove the polymer from the edges of the silicon nitride layer and to remove portions of the masking layer while leaving other portions of the masking layer remaining over the silicon nitride layer;after the dry etching, further extending the openings into the substrate; andafter the further extending, forming oxide within the openings in the substrate, the oxide within the openings forming at least portions of isolation regions.