A method for manufacturing a semiconductor device includes forming a conductive pattern on a substrate, forming a filling insulation layer covering the conductive pattern, forming a contact hole in the filling insulation layer and adjacent to the conductive pattern, forming an opening in the conductive pattern by removing a portion of the conductive pattern adjacent to the contact hole such that the opening is connected to the contact hole, and forming a contact plug filling the contact hole and the opening. A width of the opening is greater than a width of the contact hole.