A method for manufacturing a semiconductor device includes forming an etch-target layer over a semiconductor substrate having a lower structure, forming a first mask pattern over the etch-target layer, forming a spacer material layer with a uniform thickness over the etch-target layer including the first mask pattern, forming a second mask pattern on an indented region of the space material layer, and etching the etch-target layer with the first mask pattern and the second mask pattern as an etch mask to form a fine pattern.