Nonvolatile semiconductor memory device and method for manufacturing same

1. A method for manufacturing a nonvolatile semiconductor memory device,

the nonvolatile semiconductor memory device comprising:

a stacked structural unit including a plurality of insulating films alternately stacked with a plurality of electrode films in a first direction;

a selection gate electrode stacked on the stacked structural unit in the first direction;

an insulating layer stacked on the selection gate electrode in the first direction;

a first semiconductor pillar piercing the stacked structural unit, the selection gate electrode, and the insulating layer in the first direction, a first cross section of the first semiconductor pillar having an annular configuration, the first cross section being cut in a plane orthogonal to the first direction;

a first core unit buried in an inner side of the first semiconductor pillar, the first core unit being recessed from an upper face of the insulating layer; and

a first conducting layer of the first semiconductor pillar provided on the first core unit to contact the first core unit,

the method comprising:

forming the stacked structural unit including the insulating film alternately stacked with the electrode film on a major surface of a substrate;

forming the selection gate electrode on the stacked structural unit;

forming the insulating layer on the selection gate electrode;

making a first through-hole piercing at least the selection gate electrode and the insulating layer in the first direction perpendicular to the major surface and forming a first semiconductor film on an inner side face of the first through-hole;

forming the first core unit on an inner side of the first semiconductor film;

recessing the core unit; and

introducing an impurity into the first semiconductor film.

2. The method according to claim 1 , wherein the introducing of the impurity includes at least one introducing selected from vapor phase diffusion of an impurity or ion implantation.

3. The method according to claim 1 , wherein the introducing of the impurity includes irradiating the impurity on the recessed core unit, causing a travel direction of the impurity to have a component in a direction orthogonal to the first direction, and introducing the impurity into the first semiconductor film.

4. The method according to claim 1 , further comprising filling a conducting material into the first through-hole and onto the first semiconductor film including the introduced impurity to form the first conducting layer in contact with the core unit.

5. The method according to claim 1 , further comprising;

making a second through-hole and a third through-hole, the second through-hole piercing the selection gate electrode in the first direction perpendicular to the major surface, the third through-hole piercing the insulating layer in the first direction to communicate with the second through-hole, a diameter of the third through-hole at an upper end of the insulating layer being larger than a diameter of the second through-hole;

forming a second semiconductor film on an inner side faces of the second through-hole and the third through-hole; and

implanting an impurity into a portion of the second semiconductor film on the selection gate electrode side.