Semiconductor memory device having memory cells arranged three-dimensionally and method of manufacturing the same

A semiconductor memory device comprising:

• a substrate that has a memory region extending in first and second directions along a surface of the substrate, a step region that is adjacent to the memory region in the first direction and extends in the second direction, and a non-memory peripheral region that is adjacent to the memory region and the step region in the second direction and extends in the first direction;
• a plurality of insulating layers and a plurality of wiring layers that are alternately formed on the memory region and the step region of the substrate, wherein widths of the insulating layers on the step region in the first direction and widths of the wiring layers on the step region in the first direction, respectively, become narrower as a distance from the substrate increases;
• and
• a plurality of first layers and a plurality of second layers that are alternately formed on the non-memory peripheral region of the substrate, each of the first layers being formed on a same level as and in contact with one of the insulating layers, and each of the second layers being formed on a same level as and in contact with one of the wiring layers.