Patent ID: 7531449
Filing Date: 2009-05-12
Classification: H01L

Abstract:
1. A method of forming a plurality of contact holes in a material layer formed on a substrate, the method comprising: forming a parallel plurality of first hard mask patterns separated by a first pitch in a first direction on the material layer; after forming the parallel plurality of first hard mask patterns, forming a self-aligned parallel plurality of second hard mask patterns interleaved with the first hard mask patterns and separated from the first hard mask patterns by a buffer layer to form composite mask patterns comprising the first hard mask patterns and the second hard mask patterns; after forming the parallel plurality of second hard mask patterns, forming a plurality of upper mask patterns in a second direction intersecting the first direction to mask selected portions of the buffer layer in conjunction with the composite mask patterns; etching non-selected portions of the buffer layer using the composite hard mask patterns and the upper mask patterns as an etch mask to form a plurality of hard mask holes exposing selected portions of the material layer between one of the first hard mask patterns and one of the second hard mask patterns, wherein all of the second hard mask patterns remain between adjacent ones of the first hard mask patterns after etching of the non-selected portions of the buffer layer; and etching the selected portions of the material layer to form the plurality of contact holes.