US Patent 10950619 Semiconductor memory device

A semiconductor memory device includes a substrate including a cell array region and a pad region, a stack structure disposed on the cell array region and the pad region of the substrate and including gate electrodes, a device isolation layer vertically overlapping the stack structure and disposed in the pad region of the substrate, a dummy vertical channel portion penetrating the stack structure on the pad region of the substrate and disposed in the device isolation layer, and a dummy semiconductor pillar disposed between the dummy vertical channel portion and one portion of the substrate being in contact with one sidewall of the device isolation layer.