Patent ID: 6403486
Filing Date: 2002-06-11
Classification: H01L

Abstract:
A method of forming a shallow trench isolation comprising the steps of:providing a substrate; forming a first oxide layer over said substrate; forming a nitride layer over said first oxide layer; forming a second oxide layer over said nitride layer; patterning said second oxide, said nitride and said first oxide layers to form an opening in said layers reaching the surface of said substrate; forming a conformal polysilicon layer over said substrate including over the inside walls of said opening; forming a polyoxide layer by oxidizing said polysilicon layer; forming polyoxide spacers along the vertical walls of said opening while at the same time etching away said polyoxide layer from the surface of said substrate and from the bottom wall of said opening, thus exposing the surface of said substrate; etching further said substrate through said opening to form a trench in said substrate; forming a thermal oxide liner over said substrate, including over said polyoxide spacers in said opening and over the inside walls of said trench; forming a trench oxide over said substrate, including over said opening and said trench in said substrate; planarizing said trench oxide; and stripping said nitride and said first oxide layers to form said shallow trench isolation of the invention.