Method for manufacturing contact structure capable of avoiding short-circuit

Claim 1

A method for manufacturing a contact structure, comprising the steps of: forming a first insulating layer on a semiconductor substrate; forming a first conductive layer on said first insulating layer; forming a silicon nitride layer directly on said first conductive layer; forming a first pattern layer on said silicon nitride layer; anisotropically etching said silicon nitride layer and said first conductive layer with a mask of said first pattern layer where an etching rate of said silicon nitride layer by said anisotropical etching step is about the same as an etching rate of said first conductive layer by said anisotropical etching step, whereby edges of said silicon nitride layer and said first conductive layer are etched approximately perpendicularly; removing said first pattern layer; oxidizing said first conductive layer with a mask of said silicon nitride layer to form a sidewall insulating layer on a sidewall of said first conductive layer, after said first pattern layer is removed, said first conductive layer being oxidized without forming a spacer; forming a second insulating layer on said first insulating layer, said silicon nitride layer and said sidewall insulating layer after said first conductive layer is oxidized; forming a second pattern layer on said second insulating layer; perforating a contact hole in said second insulating layer and said first insulating layer; removing said second pattern layer; and burying a second conductive layer in said contact hole.

Claim 2

A method for manufacturing a contact structure, comprising the steps of: forming a first insulating layer on a semiconductor substrate; forming a first conductive layer on said first insulating layer; forming a silicon nitride layer directly on said first conductive layer; forming a first pattern layer on said silicon nitride layer; anisotropically etching said silicon nitride layer and said first conductive layer with a mask of said first pattern layer where an etching rate of said silicon nitride layer by said anisotropical etching step is about the same as an etching rate of said first conductive layer by said anisotropical etching step, whereby edges of said silicon nitride layer and said first conductive layer are etched approximately perpendicularly; removing said first pattern layer; oxidizing said first conductive layer with a mask of said silicon nitride layer to form a sidewall insulating layer on a sidewall of said first conductive layer, after said first pattern layer is removed, said first conductive layer being oxidized without forming a spacer; forming a second insulating layer on said first insulating layer, said silicon nitride layer and said sidewall insulating layer after said first conductive layer is oxidized; forming a second pattern layer on said second insulating layer; perforating a contact hole in said second insulating layer and said first insulating layer; removing said second pattern layer; and burying a second conductive layer in said contact hole.