Three-dimensional nonvolatile memory device and a method of fabricating the same

A three-dimensional nonvolatile memory device, comprising:

• a first substrate including a cell area and an extension area arranged at a side of the cell area in a first direction, wherein the extension area has a staircase structure;
• a vertical structure extending in a vertical direction from an upper surface of the first substrate;
• a stacking structure having electrode layers and interlayer insulating layers alternately stacked on the first substrate along a side wall of the vertical structure;
• a separation insulating layer extending on the first substrate in the first direction and separating the electrode layers in a second direction that intersects the first direction;
• and
• a through-via wiring area adjacent to the cell area or the extension area and having through-vias passing through the first substrate,
• wherein the cell area comprises a main cell area in which normal cells are arranged and an edge cell area at a peripheral part of the cell area,
• the separation insulating layer comprises a main separation insulating layer in the main cell area and an edge separation insulating layer in the edge cell area, and
• a lower surface of the main separation insulating layer is higher than the upper surface of the first substrate and has a different depth from that of a lower surface of the edge separation insulating layer.