Provided is a semiconductor device that can include a lower interconnection on a substrate and at least one upper interconnection disposed on the lower interconnection. At least one gate structure can be disposed between the upper interconnection and the lower interconnection, where the gate structure can include a plurality of gate lines that are vertically stacked so that each of the gate lines has a wiring portion that is substantially parallel to an upper surface of the substrate and a contact portion that extends from the wiring portion along a direction penetrating an upper surface of the substrate. At least one semiconductor pattern can connect the upper and lower interconnections.