US Patent 9985048 Semiconductor device and manufacturing method thereof

A semiconductor device includes a first structure, a dummy buffer stack structure, a peripheral contact hole, and a peripheral contact plug. The first structure may include a substrate and a peripheral circuit disposed on the substrate. The dummy buffer stack structure may be disposed on the first structure. The dummy buffer stack structure may include dummy interlayer insulating layers and dummy sacrificial insulating layers, which are alternately stacked, and first dummy conductive rings stacked in a line inside the respective dummy sacrificial insulating layers. The peripheral contact hole may penetrate the dummy buffer stack structure. The peripheral contact hole may be surrounded by the first dummy conductive rings. The peripheral contact plug may be disposed in the peripheral contact hole. The peripheral contact plug may extend to be connected to the peripheral circuit.