Method of forming fine patterns of semiconductor device

Abstract

A method of forming fine patterns includes patterning a hard mask layer and a buffer mask layer sequentially stacked on a lower mask layer to form first openings, forming sacrificial patterns filling the first openings and protruding from a top surface of the buffer mask layer, forming a spacer pattern filling a space between two adjacent sacrificial patterns and having gaps each of which exposes a portion of the buffer mask layer between at least three adjacent sacrificial patterns, etching portions of the buffer mask layer exposed by the gaps of the spacer pattern to form enlarged holes, etching portions of the hard mask layer exposed by the enlarged holes to form second openings, and subsequently etching the lower layer using the hard mask layer as an etch mask.