Method of fabricating the semiconductor memory device including channel pillar
Provided is a method of fabricating the semiconductor memory device. A stack layer, which includes sacrificial layers and first insulating interlayers alternately stacked, is formed. The sacrificial layers are positioned at an uppermost layer of the stack layer. A plurality of channel holes are formed through the stack layer. A first channel pillar is formed in each of the channel holes. A mold layer is formed on the stack layer with the first channel pillar. The mold layer includes a mold hole configured to partially expose the first channel pillar. A second channel pillar is formed in the mold hole. The mold layer and the sacrificial layer at the uppermost layer of the stack layer are then removed.
1 . A method of manufacturing a semiconductor memory device, the method comprising:
forming a stack layer including sacrificial layers and first insulating interlayers that are alternately stacked, the sacrificial layer positioned at an uppermost layer of the stack layer;
forming a channel holes through the stack layer;
forming a first channel pillar in the channel holes;
forming a mold layer on the stack layer with the first channel pillar;
etching the mold layer to open a center portion of the first channel pillar, to form a mold hole, wherein an edge portion of the first channel pillar is covered by the mold layer;
forming a second channel pillar in the mold hole; and
removing the mold layer and the uppermost sacrificial layer, to expose a sidewall of the second channel pillar, an upper surface of the second channel pillar, and an upper surface of the first channel pillar located outside the second channel pillar.
2 . The method of claim 1 , wherein forming the first channel pillar comprises:
forming a memory layer on a surface of the channel hole;
forming a first channel layer on the memory layer;
forming a core pillar on the first channel layer to partially fill the channel hole; and
forming a second channel layer on the core pillar to contact an end of the first channel layer.
3 . The method of claim 1 , wherein forming the mold layer with the mold hole comprises self-aligning a center line of the second channel pillar in a vertical direction with a center line of the first channel pillar in the vertical direction.
4 . The method of claim 1 , wherein the mold layer comprises a material the same as a material of the sacrificial layer.
5 . The method of claim 1 , wherein the second channel pillar has a diameter less than a diameter of the first channel pillar.
6 . The method of claim 1 , further comprising:
forming a gate insulation layer on the sidewall of the second channel pillar, the upper surface of the second channel pillar, and the upper surface;
forming a conductive layer with a thickness lower than a height of the second channel pillar on both sides of the second channel pillar; and
forming a second insulating interlayer on the conductive layer.
7 . The method of claim 6 , further comprising forming at least one isolation layer configured to penetrate the second insulating interlayer and the conductive layer, wherein the conductive layer is divided into at least two conductive patterns spaced apart from each other by the isolation layer.
8 . The method of claim 6 , further comprising forming at least one isolation layer configured to penetrate the uppermost sacrificial layer and an uppermost first insulating interlayer before forming the channel hole.
9 . The method of claim 6 , wherein forming the conductive layer with the thickness lower than a height of the second channel pillar comprises:
etching-back the conductive layer to expose the gate insulation layer located on the sidewall of the second channel pillar.
10 . The method of claim 6 , further comprising:
forming a third insulating interlayer on the second insulating interlayer;
selectively etching the third insulating interlayer and the second insulating interlayer to form a contact hole configured to expose the second channel pillar; and
forming a contact plug in the contact hole.
11 . The method of claim 10 , further comprising implanting impurities into the second channel pillar exposed through the contact hole to form a junction region, before forming the contact plug in the contact hole.
12 . The method of claim 10 , wherein an upper surface of the second channel pillar and an upper sidewall of the second channel pillar are inserted into a lower surface of the contact plug.