A semiconductor device may include a first cell structure, a second cell structure, a pad structure, a circuit, and one or more openings. The pad structure may be disposed between the first cell structure and the second cell structure, and may be electrically coupled to the first and second cell structures. The pad structure may have a plurality of stepped structures. The circuit may be disposed under the pad structure. The one or more openings may pass through the pad structure, and may expose the circuit. The one or more openings may be disposed between the plurality of stepped structures.