Semiconductor device and method for manufacturing same
According to one embodiment, a semiconductor device includes a foundation layer, a stacked body provided above the foundation layer, a semiconductor body, and a charge storage portion. The stacked body includes a plurality of electrode layers stacked with an air gap interposed, a plurality of select gate layers stacked in a stacking direction of the electrode layers, and an insulating body provided between the select gate layers adjacent to each other in the stacking direction. The semiconductor body extends in the stacking direction in the stacked body. The charge storage portion is provided between the semiconductor body and one of the electrode layers.
1. A semiconductor device, comprising:
a foundation layer;
a stacked body provided above the foundation layer, the stacked body including a plurality of electrode layers stacked with an air gap interposed, a plurality of select gate layers stacked in a stacking direction of the electrode layers, and an insulating body provided between the select gate layers adjacent to each other in the stacking direction, the select gate layers including a plurality of drain-side select gates, the drain-side select gates being provided above an uppermost electrode layer of the electrode layers, and the drain-side select gates being adjacent to each other in the stacking direction with the insulating body interposed;
a semiconductor body extending in the stacking direction in the stacked body;
a charge storage portion provided between the semiconductor body and one of the electrode layers; and
a side wall film provided on a side wall of a portion in a slit, the drain-side select gates and the insulating body being stacked in the portion, the slit dividing the stacked body into a plurality of blocks and being connected to the air gap.
2. The device according to claim 1 , further comprising a sealing film which closes an upper end of the slit in a vicinity of an upper end of the side wall film.
3. A semiconductor device, comprising:
a foundation layer;
a stacked body provided above the foundation layer, the stacked body including a plurality of electrode layers stacked with an air gap interposed, a plurality of select gate layers stacked in a stacking direction of the electrode layers, and an insulating body provided between the select gate layers adjacent to each other in the stacking direction, the select gate layers including a plurality of source-side select gates, the source-side select gates being provided below a lowermost electrode layer of the electrode layers, and the source-side select gates being adjacent to each other in the stacking direction with the insulating body interposed;
a semiconductor body extending in the stacking direction in the stacked body;
a charge storage portion provided between the semiconductor body and one of the electrode layers; and
a cover film provided on a lateral side of the insulating body in a slit which divides the stacked body into a plurality of blocks.
4. The device according to claim 3 , further comprising a drain-side select gate provided above the stacked body, the drain-side select gate being thicker than a thickness of one layer of the electrode layers and a thickness of one layer of the source-side select gates.
5. The device according to claim 3 , further comprising an insulating film provided on a lateral side of the stacked body in a slit which divides the stacked body into a plurality of blocks, the insulating film closing an end portion of the air gap.
6. The device according to claim 5 , further comprising a cap film provided between a slit side end portion of one of the electrode layers and the insulating film.
7. The device according to claim 3 , wherein the stacked body further includes a conductive layer provided between the foundation layer and a lowermost source-side select gate, the conductive layer being thicker than a thickness of one layer of the electrode layers and a thickness of one layer of the select gate layers.
8. A semiconductor device, comprising:
a foundation layer;
a stacked body provided above the foundation layer, the stacked body including a plurality of electrode layers stacked with an air gap interposed, a plurality of select gate layers stacked in a stacking direction of the electrode layers, and an insulating body provided between the select gate layers adjacent to each other in the stacking direction;
a semiconductor body extending in the stacking direction in the stacked body; and
a charge storage portion provided between the semiconductor body and one of the electrode layers,
the foundation layer includes a semiconductor region doped with an impurity, and
the semiconductor body is in contact with the semiconductor region.
9. A method for manufacturing a semiconductor device, comprising:
forming a stacked body above a foundation layer, the stacked body including a plurality of first films and a plurality of second films, the first films and the second films including a first film and a second film stacked alternately;
forming a slit which divides the stacked body into a plurality of blocks;
forming a cover film in the slit such that an upper end of the cover film is positioned at a height not higher than at least an upper surface of the first film being a second layer from a top;
forming a side wall film on a side surface of the slit above the cover film;
after removing the cover film or retreating the upper end while leaving the side wall film, removing the second film having a slit side end portion not covered with the side wall film and the cover film by etching through the slit, thereby forming an air gap in a portion from which the second film is removed; and
forming a sealing film which closes an upper end of the slit while leaving the air gap.
10. The method according to claim 9 , wherein
the sealing film closes the upper end of the slit in a vicinity of an upper end of the side wall film, and
the air gap is connected to an internal space of the slit closed by the sealing film.
11. The method according to claim 9 , wherein
after forming the side wall film, the upper end of the cover film is retreated while at least a slit side end portion of the second film between a lowermost first film and the first film being a second layer from a bottom is covered with the cover film, and
the second film between the lowermost first film and the first film being the second layer from the bottom is left without being removed.
12. A method for manufacturing a semiconductor device, comprising:
forming a stacked body above a foundation layer, the stacked body including a plurality of first films and a plurality of second films, the first films and the second films including a first film and a second film stacked alternately;
forming a slit which divides the stacked body into a plurality of blocks;
forming a cover film on a bottom of the slit to a height so as to cover at least a lateral side of a lowermost second film on the foundation layer; and
removing the second film positioned above an upper end of the cover film of the second films by etching through the slit after forming the cover film, thereby forming an air gap in a portion from which the second film is removed.
13. The method according to claim 12 , wherein the cover film covers a lateral side of the second films on a lower layer side including the lowermost second film, and the second films on the lower layer side are left without being removed.
14. The method according to claim 12 , further comprising:
forming an insulating film which closes a slit side end portion of the air gap; and
forming an upper-side select gate layer above the stacked body after forming the insulating film.
15. The method according to claim 12 , further comprising replacing the first film with an electrode layer through the slit before forming the cover film.
16. The method according to claim 15 , further comprising forming a cap film which covers a slit side end portion of the electrode layer before forming the cover film.