US Patent 10109644 Memory device

In one embodiment, the semiconductor device includes a substrate having an impurity region, and the substrate and the impurity region have a different impurity characteristic. The semiconductor device further includes a stack of alternating first interlayer insulating layers and gate electrode layers on the substrate; at least one second interlayer insulating layer formed on the stack; a plurality of bit lines formed on the second interlayer insulating layer; and a first plurality of channel structures formed through the stack on the substrate. The first plurality of channel structures are electrically connected to respective ones of the plurality of bit lines. A second plurality of channel structures are formed through the stack on the impurity region, and the second plurality of channel structures are electrically insulated from the plurality of bit lines.