Patent ID: 6878612

Claim:
A method for manufacturing a self alignment contact in a semiconductor device including a first silicon oxide film formed at a surface of a silicon substrate, a poly-silicon film and a second silicon oxide film laminated on top of said first silicon oxide film, thereby forming a first electrode and a second electrode each constituted of said poly-silicon film and said second silicon oxide film, a silicon nitride film formed to cover top and side surfaces of said first electrode and said second electrode, and a third silicon oxide film formed in an area between said first electrode and said second electrode that are covered with said silicon nitride film, and over a top of said silicon nitride film formed on said first electrode and on said second electrode, the method comprising: a first etching process in which said third silicon oxide film is etched to open up said third silicon oxide film above the top of said silicon nitride film, wherein said first etching process uses a first etching gas mixture including CF 4 , argon and O 2 ; and a second etching process in which said third silicon oxide film between said first electrode and said second electrode is removed by etching said third silicon oxide film, wherein said second etching process uses a second etching gas mixture that is different than the first etching gas mixture and that does not contain oxygen, wherein a sum of an opening area at said third silicon oxide film and an area over which a resist is removed from a peripheral area of said silicon substrate is kept at a constant value by removing the resist at the peripheral area of said silicon substrate prior to the first etching process.