A method for fabricating a semiconductor device includes forming a plurality of isolation patterns, isolated from each other by a plurality of trenches, over an underlying structure; forming a plurality of conductive lines filled in the trenches, forming contact holes by removing first portions of the isolation patterns, wherein the contact holes are defined by the plurality of conductive lines and second portions of the isolation patterns that remain after removing of the first portions of the isolation patterns, and forming plugs filled in the contact holes.