Semiconductor device and method for manufacturing semiconductor device

1. A semiconductor device, comprising:

a substrate;

a stacked body provided above the substrate, the stacked body including a plurality of electrode layers stacked with an air gap interposed, the stacked body including a stairstep portion in which the electrode layers are arranged in a stairstep configuration with a difference in levels in a first direction;

a first columnar portion including a semiconductor body and a stacked film, the semiconductor body extending in a stacking direction through the stacked body, the stacked film including a charge storage portion and being provided between the semiconductor body and the electrode layers;

an insulating layer provided above the stairstep portion;

a first cover film provided between the stairstep portion and the insulating layer, the first cover film being of a material different from the insulating layer, the first cover film covering edges in the first direction of the electrode layers of the stairstep portion, and plugging the air gap between the electrode layers of the stairstep portion;

a separation portion extending in the stacking direction and the first direction, and dividing the stacked body and the insulating layer in a second direction intersecting the first direction; and

a second cover film provided at a side surface of the insulating layer on the separation portion side, the second cover film being of a material different from the insulating layer.

2. The semiconductor device according to claim 1 , wherein

one portion of the first cover film plugging the air gap is provided between a tip portion of one electrode layer of the stairstep portion on the edge side and another electrode layer under the tip portion, and

the tip portion of the one electrode layer is supported, via the one portion of the first cover film, on another electrode layer under the tip portion.

3. The semiconductor device according to claim 2 , further comprising a contact via contacting the one electrode layer of the stairstep portion and extending in the stacking direction through the insulating layer,

the one portion of the first cover film spreading to a region overlapping a lower end of the contact via.

4. The semiconductor device according to claim 1 , further comprising a contact via contacting one electrode layer of the stairstep portion and extending in the stacking direction through the insulating layer.

5. The semiconductor device according to claim 1 , wherein

the insulating layer is a silicon oxide layer, and

the first cover film and the second cover film are a silicon nitride film or a metal oxide film.

6. The semiconductor device according to claim 1 , wherein

the separation portion includes:

an interconnect portion; and

an insulating film provided between the interconnect portion and the second cover film, and between the interconnect portion and the stacked body.

7. The semiconductor device according to claim 1 , further comprising a third cover film provided on the insulating layer, the third cover film being of a material different from the insulating layer.

8. The semiconductor device according to claim 7 , further comprising a second columnar portion extending in the stacking direction through the stacked body of the stairstep portion, through the insulating layer above the stairstep portion, and through the first cover film between the stairstep portion and the insulating layer.

9. The semiconductor device according to claim 8 , wherein the third cover film covers an upper end of the second columnar portion.