Method of manufacturing semiconductor memory device having charge accumulation layer positioned between control gate electrode and semiconductor layer
View Patent ↗According to an embodiment, a semiconductor memory device includes a plurality of control gate electrodes, a semiconductor layer, and a charge accumulation layer. The plurality of control gate electrodes are provided as a stack above a substrate. The semiconductor layer has as its longitudinal direction a direction perpendicular to the substrate, and faces the plurality of control gate electrodes. The charge accumulation layer is positioned between the control gate electrode and the semiconductor layer. A lower end of the charge accumulation layer is positioned more upwardly than a lower end of a lowermost layer-positioned one of the control gate electrodes.
1. A method of manufacturing a semiconductor memory device, the semiconductor memory device comprising: a plurality of control gate electrodes stacked above a substrate; a semiconductor layer having as its longitudinal direction a direction perpendicular to the substrate, the semiconductor layer facing the plurality of control gate electrodes; and a charge accumulation layer positioned between the control gate electrode and the semiconductor layer, the method comprising:
alternately stacking a plurality of first insulating layers and first layers on the substrate to form a stacked body;
forming an opening that penetrates some of the first insulating layers and the first layers of the stacked body;
forming the charge accumulation layer on the inside of the opening;
removing a portion of the stacked body positioned in a bottom portion of the opening;
forming the semiconductor layer on the inside of the opening;
after forming the semiconductor layer, removing the first layer; and
forming the control gate electrode between a plurality of the first insulating layers adjacent in the direction perpendicular to the substrate.
2. The method of manufacturing a semiconductor memory device according to claim 1 , comprising:
after removing the portion of the stacked body positioned in the bottom portion of the opening and before forming the semiconductor layer,
forming a second insulating layer and a protective layer on the inside of the opening; and
removing portions of the protective layer and the second insulating layer positioned in the bottom portion of the opening.
3. The method of manufacturing a semiconductor memory device according to claim 1 , wherein
the semiconductor layer is formed by a method that grows a crystal.
4. The method of manufacturing a semiconductor memory device according to claim 3 , comprising
when forming the semiconductor layer, growing the crystal such that an N type or a P type impurity is included in the formed semiconductor layer.
5. The method of manufacturing a semiconductor memory device according to claim 1 , wherein
the semiconductor layer is formed by repeatedly performing:
a method that grows a first crystalline portion having a monocrystalline structure, in a portion contacting a monocrystal, and grows a second crystalline portion having an amorphous crystalline structure, in a certain other portion; and
a method that removes at least part of the second crystalline portion under such a condition that the second crystalline portion is removed faster than the first crystalline portion.