Method of forming fine patterns using double patterning process

Abstract

A double pattern method of forming a plurality of contact holes in a material layer formed on a substrate is disclosed. The method forms a parallel plurality of first hard mask patterns separated by a first pitch in a first direction on the material layer, 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, and 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. The method then etches 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, and then etches the selected portions of the material layer to form the plurality of contact holes.