Semiconductor memory device and method for manufacturing same

A method for manufacturing a semiconductor memory device, comprising:

• forming a first insulating film on a substrate;
• forming a first electrode film on the first insulating film;
• forming a first through-hole in the first insulating film and the first electrode film, the first through-hole piercing the first insulating film and the first electrode film and reaching the substrate;
• forming a first film inside the first through-hole;
• forming a stacked body on the first electrode film and the first film by alternately stacking a second insulating film and a second electrode film;
• forming a second through-hole in the stacked body to pierce the stacked body and reach the first film, a width in a direction perpendicular to a stacking direction of the stacked body being larger for the second through-hole than for the first through-hole;
• removing the first film inside the first through-hole via the second through-hole;
• and
• forming a columnar portion inside the first through-hole and the second through-hole, the columnar portion including a semiconductor portion.

A method for manufacturing a semiconductor memory device, comprising:

• forming a first insulating film on a substrate;
• forming a first electrode film on the first insulating film;
• forming a stacked body on the first electrode film by alternately stacking a second insulating film and a second electrode film;
• forming a first through-hole reaching the first electrode film by removing a portion of the stacked body;
• forming a third insulating film on an inner surface of the first through-hole;
• forming a second through-hole reaching the substrate by removing a portion of the third insulating film, a portion of the first electrode film, and a portion of the first insulating film via the first through-hole, a width in a direction perpendicular to a stacking direction of the stacked body being smaller for the second through-hole than for the first through-hole;
• forming a fourth insulating film inside the first through-hole and the second through-hole;
• and
• forming a semiconductor portion on the fourth insulating film inside the first through-hole and the second through-hole.