Semiconductor memory device and method for manufacturing the same
According to one embodiment, a semiconductor memory device includes a stacked body including a plurality of electrode members and a plurality of insulating members, each of the electrode members and each of the insulating members being stacked alternately in a first direction on the substrate. The semiconductor memory device also includes a memory hole that extends in the stacked body in the first direction and a semiconductor member that is disposed to extend in the memory hole in the first direction. The semiconductor memory device also includes a memory member that is disposed between the semiconductor member and the plurality of electrode members. The plurality of electrode members including a first electrode member and a second electrode member, a thickness of the memory member at the position of the first electrode member being greater than a thickness of the memory member at the position of the second electrode member.
1. A method for manufacturing a semiconductor memory device comprising:
forming a first electrode member on a flat surface perpendicular to a first direction,
forming a second electrode member parallel to the first electrode member, the second electrode member being disposed above the first electrode member,
forming a memory hole that penetrates the first electrode member and the second electrode member in the first direction from above, a diameter of the memory hole at a position of the first electrode member being made smaller than a diameter of the memory hole at a position of the second electrode member,
forming a first charge storage portion on a side surface of the first electrode member via an insulating material and a second charge storage portion on a side surface of the second electrode member via the insulating material,
forming a first insulating member and a second insulating member by oxidizing the first charge storage portion and the second charge storage portion, a thickness of first charge storage portion being made smaller than a thickness of the second charge storage portion after the oxidation, and
forming a semiconductor layer at an inner side of the first insulating member and the second insulating member.
2. The method according to claim 1 , wherein the oxidation includes radical oxidation, thermal oxidation, or plasma oxidation.
3. The method according to claim 1 , wherein the first insulating member and the second insulating member contain silicon oxide.
4. The method according to claim 1 , wherein the first insulating member and the second insulating member contain silicon oxynitride.
5. The method according to claim 1 , wherein a thickness of the first insulating member is larger than a thickness of the second insulating member.
6. The method according to claim 1 , further comprising:
forming a third insulating member on a side surface of the first insulating member and the second insulating member.
7. The method according to claim 6 , wherein the third insulating member contains silicon oxide.
8. The method according to claim 7 , further comprising:
forming a fourth insulating member on a side surface of the first insulating member and the second insulating member before the forming the third insulating member.