Method for manufacturing semiconductor device and semiconductor device
According to one embodiment, a method is disclosed for manufacturing a semiconductor device. The second insulating film seals the hole near an interface of the insulating layer and the select gate. The second insulating film is provided on a side wall of the channel body with a space left in the hole above the select gate. The method can include burying a semiconductor film in the space, in addition, forming a conductive film in contact with the channel body.
1. A method for manufacturing a semiconductor device comprising:
forming a stacked body on a substrate, the stacked body including a select gate and an insulating layer, the insulating layer being provided on the select gate;
forming a hole piercing the stacked body;
forming a first insulating film on a side wall of the hole;
forming a channel body on a side wall of the first insulating film;
forming a second insulating film sealing the hole near an interface of the insulating layer and the select gate, the second insulating film being provided on a side wall of the channel body with a space left in the hole above the select gate and having a film thickness in a side wall portion surrounding the space thinner than a film thickness in a bottom portion sealing the hole;
burying a semiconductor film in the space; and
forming a conductive film in contact with the channel body on an inside of the channel body in the hole on the semiconductor film.
2. The method according to claim 1 , wherein the second insulating film is formed by a film-formation method in which a deposition rate in a vertical direction of the hole is higher than a deposition rate in a lateral direction of the hole.
3. The method according to claim 2 , wherein the second insulating film is formed by a plasma CVD (chemical vapor deposition) method.
4. The method according to claim 1 , wherein the semiconductor film is a non-doped silicon film.
5. The method according to claim 1 , further comprising expanding a hole diameter of a portion surrounded by the insulating layer by wet etching to form a level difference between a side wall of an upper end of the select gate and a side wall of the insulating layer after forming the hole.
6. The method according to claim 1 , further comprising implanting the channel body with an impurity before forming the second insulating film.
7. A method for manufacturing a semiconductor device comprising:
forming a stacked body on a substrate, the stacked body including a select gate and an insulating layer, the insulating layer being provided on the select gate;
forming a hole piercing the stacked body;
forming a first insulating film on a side wall of the hole;
forming a channel body on a side wall of the first insulating film;
forming a second insulating film sealing the hole near an interface of the insulating layer and the select gate, the second insulating film being provided on a side wall of the channel body with a space left in the hole above the select gate;
etching back the second insulating film to remove an upper portion of the second insulating film covering a corner portion between an upper end of the insulating layer and a side wall of the channel body while leaving a bottom portion sealing the hole;
burying a semiconductor film in the space after the etching back the second insulating film; and
forming a conductive film in contact with the channel body on an inside of the channel body in the hole on the semiconductor film.
8. The method according to claim 7 , wherein the second insulating film is formed by an ALD (atomic layer deposition) method.
9. The method according to claim 7 , wherein the semiconductor film is a non-doped silicon film.
10. The method according to claim 7 , further comprising expanding a hole diameter of a portion surrounded by the insulating layer by wet etching to form a level difference between a side wall of an upper end of the select gate and a side wall of the insulating layer after forming the hole.
11. The method according to claim 7 , wherein the second insulating film is etched back by an RIE (reactive ion etching) method.
12. The method according to claim 7 , wherein a side wall portion of the second insulating film is formed in a tapered shape by the etching back.
13. The method according to claim 7 , further comprising implanting the channel body with an impurity before forming the second insulating film.
14. A semiconductor device comprising:
a substrate;
a stacked body including a select gate provided on the substrate and an insulating layer provided on the select gate;
a first insulating film provided on a side wall of a hole piercing the stacked body;
a channel body provided on a side wall of the first insulating film;
a second insulating film sealing the hole near an interface of the insulating layer and the select gate, and provided on a side wall of the channel body above the select gate;
a semiconductor film buried in an inside of the second insulating film in the hole above the select gate; and
a conductive film provided in contact with the channel body on an inside of the channel body in the hole on the semiconductor film,
the second insulating film having a bottom portion sealing the hole, and a side wall portion surrounding a periphery of the semiconductor film, the side wall portion having a film thickness thinner than a film thickness of the bottom portion.
15. The device according to claim 14 , wherein the semiconductor film is a non-doped silicon film.
16. The device according to claim 14 , wherein the conductive film is a silicon film doped with an impurity.
17. The device according to claim 14 , wherein the stacked body further includes:
a plurality of conductive layers provided between the substrate and the select gate; and
a plurality of second insulating layers each provided between adjacent ones of the conductive layers.
18. The device according to claim 17 , further comprising a memory film provided between the conductive layer and the channel body, the memory film including a charge storage film.
19. The device according to claim 14 , wherein a level difference is formed between a side wall of an upper end of the select gate and a side wall of the insulating layer.
20. The device according to claim 19 , wherein
the channel body has a level difference covering portion formed to lie along the level difference and
an impurity concentration of the level difference covering portion is higher than an impurity concentration of a side wall portion above the level difference covering portion in the channel body.