THREE-DIMENSIONAL SEMICONDUCTOR MEMORY DEVICE AND ELECTRONIC SYSTEM INCLUDING THE SAME

A three-dimensional semiconductor memory device includes a first substrate, a peripheral circuit structure on the first substrate, a cell array structure on the peripheral circuit structure, the cell array structure including a stack structure having alternating interlayer dielectric layers and gate electrodes, a first insulating layer covering the stack structure, and a second substrate on the stack structure and the first insulating layer, the stack structure being between a bottom surface of the second substrate and the peripheral circuit structure, a second insulating layer on the cell array structure, a first penetration contact penetrating the first insulating layer, the second substrate, and the second insulating layer, and a second penetration contact penetrating the first insulating layer and the second insulating layer, the second penetration contact being spaced apart from the second substrate, and the first and second penetration contacts having widths decreasing with increasing distance from the first substrate.