Semiconductor memory device having air gap

1. A semiconductor device comprising:

a substrate;

a stacked body provided above the substrate and including a plurality of electrode films stacked via a first air gap;

a second air gap penetrating through the electrode films in a stacking direction of the stacked body, the stacked body being separated into a plurality of blocks in a first direction crossing the stacking direction by the second air gap, and the second air gap communicating with the first air gap;

a first insulating film provided above the stacked body and covering an upper end of the second air gap;

a semiconductor film extending in the stacking direction in the stacked body;

a stacked film including a charge storage portion, the stacked film being provided between a side surface of one of the electrode films and a side surface of the semiconductor film opposed to the side surface of the one of the electrode films, and the stacked film being in contact with the side surface of the one of the electrode films and the side surface of the semiconductor film;

a second insulating film covering staircase-shaped end parts of the electrode films; and

a plurality of contact vias extending in the stacking direction through the second insulating film to the staircase-shaped end parts of the electrode films,

a creepage distance between the electrode films along a surface of the second insulating film adjacent to the first air gap being larger than a spacing between the electrode films adjacent in the stacking direction,

the staircase-shaped end parts having portions on which the contact vias are disposed,

upper horizontal surfaces of the portions of the staircase-shaped end parts being directly covered with the second insulating film without the first air gap interposed between the upper horizontal surfaces of the portions of the staircase-shaped end parts and the second insulating film.

2. The device according to claim 1 , wherein the stacked film includes an insulating film provided between the charge storage portion and the semiconductor film, being in contact with the side surface of the semiconductor film, and extending in the stacking direction.

3. The device according to claim 1 , wherein the side surface of the semiconductor film is covered with the stacked film and not exposed to the first air gap.

4. The device according to claim 1 , wherein a spacing between the electrode films opposed in the first direction across the second air gap is larger than a spacing between the electrode films adjacent in the stacking direction via the first air gap.

5. The device according to claim 1 , wherein the second air gap extends above an upper surface of an uppermost electrode film of the electrode films.

6. The device according to claim 5 , wherein a creepage distance along a surface of the first insulating film between the uppermost electrode films opposed across the second air gap is larger than a width in the first direction of the second air gap.

7. The device according to claim 1 , wherein the electrode films includes a first electrode film functioning a control gate of a memory cell, a second electrode film functioning a control gate of a drain side select transistor, and a third electrode film functioning a control gate of a source side select transistor, and

the second air gap penetrates through the first electrode film, the second electrode film, and the third electrode film in the stacking direction.