Method for forming a field oxide layer in a semiconductor device which prevents bird beak by nitradation of pad oxide

Abstract

A method for forming a field oxide layer in a semiconductor device comprising the steps of: forming a pad oxide layer and a first resistant layer of oxidation, in turn, on a substrate; opening a field region by etching a portion of the said resistant layer of oxidation, whereby a part of the said pad oxide layer remains; forming the pad oxide layer into a nitric oxide layer; forming a second and a third resistant layer of oxidation, in turn, on a resultant structure; forming a spacer layer by applying anisotropic etching to the third resistant layer of oxidation; exposing a portion of the substrate by etching the second resistant layer of oxidation and the pad layer which is formed into the nitride layer; and forming the field oxide layer by oxidizing the substrate.

Dependencies are inferred from the claim text.