A method of fabricating a semiconductor device is provided. A plurality of target patterns is formed on a substrate. The plurality of target patterns is extended in parallel to each other along a first direction. A first mask pattern extending in the first direction and including a plurality of first openings is formed. A second mask pattern extending in a second direction crossing the first direction and including a plurality of second openings is formed. Each second opening overlaps each first opening to form an overlapped opening region. A region of the plurality of target patterns is etched through the overlapped opening region using the first mask pattern and the second mask pattern as a etch mask. The region of the plurality of target patterns is overlapped with the overlapped opening region.