SEMICONDUCTOR MEMORY DEVICE AND METHOD OF MANUFACTURING THE SAME

The invention relates to a semiconductor memory device and a manufacturing method of the semiconductor memory device. A semiconductor memory device includes: a first gate stack structure including first interlayer insulating layers and first conductive layers alternately stacked in a vertical direction; a dummy vertical channel penetrating the first gate stack structure; penetrating a lower vertical channel of the first gate stack structure at both sides of the dummy vertical channel; a second gate stack structure including second interlayer insulating layers and second conductive layers alternately stacked on the first gate stack structure in the vertical direction; a first selection line isolation structure partially penetrating the second gate stack structure; an upper vertical channel connected to the lower vertical channel while penetrating the second gate stack structure; and a second select line isolation structure overlapping the dummy vertical channel in the vertical direction, the second select line