Patent ID: 6214715
Filing Date: 2001-04-10
Classification: H01L

Abstract:
A method for forming a self aligned contact, comprising the steps of:a. providing a semiconductor structure having a first device layer over said semiconductor structure, a first inter poly oxide layer over said first device layer, and a hard mask layer over said inter poly oxide layer; said semiconductor structure having a conductive structure thereover with sidewalls; said first device layer having a contact area thereon adjacent to said conductive structure;b. forming a first spacer layer over said hard mask and said first inter polysilicon oxide layer;c. anisotropically etching said first spacer layer to form first sidewall spacers on said sidewalls of said conductive structure up to a level above the bottom of said hard mask and below the level of the top of said hard mask;d. forming a second spacer layer over said first sidewall spacers, said first inter polysilicon oxide layer, and said hard mask;e. anisotropically etching said second sidewall spacer layer to form second sidewall spacers; whereby the profile of said second sidewall spacers is not concave at any point;f. forming a second inter poly oxide layer over said second sidewall spacers, said hard mask, and said semiconductor structure; whereby said second inter poly oxide layer is free from key holes;g. forming a contact opening in said second inter poly oxide layer and said first inter poly oxide layer over said contact area; andh. forming a contact plug in said contact opening.