Method for manufacturing a vertical nonvolatile semiconductor memory device including forming floating gates within the recesses created on the interlayer insulating films
A nonvolatile semiconductor memory device includes: forming a stacked body by alternately stacking a plurality of interlayer insulating films and a plurality of control gate electrodes; forming a through-hole extending in a stacking direction in the stacked body; etching a portion of the interlayer insulating film facing the through-hole via the through-hole to remove the portion; forming a removed portion; forming a first insulating film on inner faces of the through-hole and the portion in which the interlayer insulating films are removed; forming a floating gate electrode in the portion in which the interlayer insulating films are removed; forming a second insulating film so as to cover a portion of the floating gate electrode facing the through-hole; and burying a semiconductor pillar in the through-hole.
1. A method for manufacturing a nonvolatile semiconductor memory device comprising:
forming a stacked body by alternately stacking a plurality of interlayer insulating films and a plurality of control gate electrodes;
forming a through-hole extending in a stacking direction in the stacked body;
etching a portion of the interlayer insulating films facing the through-hole via the through-hole to remove the portion;
forming a first insulating film on inner faces of the through-hole and the portion in which the interlayer insulating films are removed;
forming a floating gate electrode made of conductive material on the first insulating film in the portion in which the interlayer insulating film is removed;
forming a second insulating film so as to cover a portion of the floating gate electrode facing the through-hole; and
burying a semiconductor pillar in the through-hole,
wherein wet etching is performed as the etching.
2. A method for manufacturing a nonvolatile semiconductor memory device comprising:
forming a stacked body by alternately stacking a plurality of interlayer insulating films and a plurality of control gate electrodes;
forming a through-hole extending in a stacking direction in the stacked body;
etching a portion of the interlayer insulating films facing the through-hole via the through-hole to remove the portion:,
forming a first insulating film on inner faces of the through-hole and the portion in which the interlayer insulating films are removed;
forming a floating gate electrode made of conductive material on the first insulating film in the portion in which the interlayer insulating film is removed;
forming a second insulating film so as to cover a portion of the floating gate electrode facing the through-hole; and
burying a semiconductor pillar in the through-hole,
wherein
the forming the floating gate electrode includes:
forming a semiconductor layer on inner faces of the through-hole and the portion in which the interlayer insulating film is removed;
removing the semiconductor layer from a bottom face of the through-hole by anisotropic etching; and
removing the semiconductor layer from a side face of the through-hole by isotropic etching.
3. The method according to claim 2 , wherein the forming the semiconductor layer is performed by depositing silicon by low pressure chemical vapor deposition.
4. The method according to claim 2 , wherein the anisotropic etching is performed by reactive ion etching.
5. The method according to claim 2 , wherein the isotropic etching is performed by chemical dry etching.