Semiconductor memory device and method for manufacturing the same

A semiconductor memory device comprising:

• a multilayer body with a plurality of first insulating films and first electrode films alternately stacked, the multilayer body including a first through hole extending in stacking direction of the first insulating films and the first electrode films;
• a second electrode film provided on the multilayer body and including a second through hole, the second through hole extending in the stacking direction and being coupled with the first through hole;
• a second insulating film provided on the second electrode film and including a third through hole, the third through hole extending in the stacking direction and being coupled with the second through hole;
• a semiconductor film provided on an inner surface of the first to third through hole;
• a memory film provided between the first electrode films and the semiconductor film;
• and
• a gate insulating film provided between the second electrode film and the semiconductor film,
• on the inner surface of the second through hole, a step difference being formed so that an upper side of the second through hole is thicker than a lower side of the second through hole.

A method for manufacturing a semiconductor memory device, comprising:

• forming a multilayer body by alternately stacking a plurality of first insulating films and first electrode films;
• forming a first through hole in the multilayer body, the first through hole extending in stacking direction of the first insulating films and the first electrode films;
• forming a memory film on an inner surface of the first through hole;
• forming a first semiconductor film on the memory film;
• forming a second electrode film on the multilayer body;
• forming a second insulating film on the second electrode film;
• forming a third through hole extending in the stacking direction in the second insulating film;
• forming a spacer film on an inner surface of the third through hole;
• forming a second through hole extending in the stacking direction in the second electrode film by etching using the second insulating film and the spacer film as a mask;
• removing the spacer film;
• forming a gate insulating film on an inner surface of the second through hole and the inner surface of the third through hole;
• forming a second semiconductor film on the gate insulating film;
• and
• implanting impurity into the second semiconductor film.

A method for manufacturing a semiconductor memory device, comprising:

• forming a multilayer body by alternately stacking a plurality of first insulating films and first electrode films;
• forming a first through hole in the multilayer body, the first through hole extending in stacking direction of the first insulating films and the first electrode films;
• forming a memory film on an inner surface of the first through hole;
• forming a first semiconductor film on the memory film;
• forming a second electrode film on the multilayer body;
• forming a second insulating film on the second electrode film;
• forming a third through hole extending in the stacking direction in the second insulating film;
• forming a second through hole extending in the stacking direction in the second electrode film by etching using the second insulating film as a mask;
• expanding the third through hole;
• forming a gate insulating film on an inner surface of the second through hole and the third through hole;
• forming a second semiconductor film on the gate insulating film;
• and
• implanting impurity into the second semiconductor film.

A method for manufacturing a semiconductor memory device, comprising:

• forming a multilayer body by alternately stacking a plurality of first insulating films and first electrode films;
• forming a first through hole in the multilayer body, the first through hole extending in stacking direction of the first insulating films and the first electrode films;
• forming a memory film on an inner surface of the first through hole;
• forming a first semiconductor film on the memory film;
• forming a second electrode film on the multilayer body;
• forming a second insulating film on the second electrode film;
• forming a third through hole extending in the stacking direction in the second insulating film;
• forming a recess in an upper part of the second electrode film by etching using the second insulating film as a mask;
• expanding the third through hole;
• forming a second through hole by etching using the second insulating film including the expanded third through hole as a mask, the second through hole extending in the stacking direction and having an inner surface with a step difference formed so that an upper side of the second through hole is thicker than a lower side of the second through hole;
• forming a gate insulating film on the inner surface of the second through hole and an inner surface of the third through hole;
• forming a second semiconductor film on the gate insulating film;
• and
• implanting impurity into the second semiconductor film.