Method of processing a substrate and a device manufactured by using the method
A method of processing a substrate by omitting a photolithographic process is disclosed. The method includes forming at least one layer on a stepped structure having an upper surface, a lower surface, and a side surface that connects the upper surface to the lower surface, selectively densifying portions of the at least one layer respectively on the upper surface and the lower surface via asymmetric plasma application, and performing an isotropic etching process on the at least one layer. During the isotropic etching process, the portion of the at least one layer formed on the upper surface is separated from the portion of the at least one layer formed on the lower surface.
1. A method of processing a substrate, the method comprising:
stacking a stacked structure including a silicon oxide layer and a first silicon nitride layer a plurality of number of times;
forming a second silicon nitride layer on the first silicon nitride layer;
forming a third silicon nitride layer on the second silicon nitride layer;
densifying the third silicon nitride layer;
wet-etching at least a portion of a sacrificial word line structure including the first silicon nitride layer, the second silicon nitride layer, and the third silicon nitride layer;
forming an interlayer insulation layer on the sacrificial word line structure;
removing the sacrificial word line structure; and
forming a conductive word line structure corresponding to a space from which the sacrificial word line structure has been removed.
2. The method of claim 1 , wherein, in the wet-etching of at least a portion of the sacrificial word line structure, an etch rate of the third silicon nitride layer is less than an etch rate of the second silicon nitride layer.
3. The method of claim 1 , further comprising:
etching the stacked structure before forming a second silicon nitride layer on the first silicon nitride layer to form a stepped structure having an upper surface, a lower surface, and a side surface that connects the upper surface to the lower surface.
4. The method of claim 3 , wherein, in the wet-etching of at least a portion of the sacrificial word line structure, an etch rate of a portion of the third silicon nitride layer on the side surface is greater than an etch rate of portions of the third silicon nitride layer on the upper and lower surfaces.
5. The method of claim 3 , wherein the wet-etching of at least a portion of the sacrificial word line structure comprises:
exposing a portion of the second silicon nitride layer formed on the side surface by removing a portion of the third silicon nitride layer formed on the side surface; and
exposing a portion of the silicon oxide layer formed on the side surface by removing the second silicon nitride layer.
6. The method of claim 5 , wherein the exposing of the portion of the second silicon nitride layer and the exposing of the portion of the silicon oxide layer are performed via a single etch process.
7. The method of claim 5 , wherein the exposing of the portion of the second silicon nitride layer and the exposing of the portion of the silicon oxide layer are performed without performing a photolithographic process.
8. The method of claim 1 , wherein a hydrogen-containing nitrogen gas is used in the forming of the second silicon nitride layer.
9. The method of claim 1 , wherein, a hydrogen-free nitrogen gas is used in the forming of the third silicon nitride layer.
10. The method of claim 1 , wherein a flow rate of a hydrogen-containing nitrogen gas used in the forming of the third silicon nitride layer is less than a flow rate of a hydrogen-containing nitrogen gas used in the forming of the second silicon nitride layer.
11. The method of claim 1 , wherein a hydrogen content of the third silicon nitride layer is less than a hydrogen content of the second silicon nitride layer.
12. The method of claim 1 , wherein the densifying is performed via an asymmetric plasma process.
13. The method of claim 12 , wherein, a gas including at least one of argon (Ar) and nitrogen is used during the asymmetric plasma process.
14. The method of claim 1 , wherein a nitrogen content of the third silicon nitride layer is greater than a nitrogen content of the second silicon nitride layer.
15. The method of claim 1 , wherein the conductive word line structure comprises:
a first conductive layer extending toward a channel;
a second conductive layer on the first conductive layer; and
a third conductive layer on the second conductive layer; and
the second conductive layer and the third conductive layer have different sidewall profiles.
16. The method of claim 15 , wherein
the first conductive layer comprises a groove, and
the groove is formed adjacent to the second conductive layer.
17. The method of claim 15 , wherein, with respect to one side surface of the second conductive layer and the third conductive layer, one end of the third conductive layer protrudes from a side surface of the second conductive layer.
18. The method of claim 17 , wherein, with respect to another side surface of the second conductive layer and the third conductive layer, one end of the second conductive layer protrudes from a side surface of the third conductive layer or vice versa.
19. A method of processing a substrate, the method comprising:
stacking a stacked structure including an insulation layer and a first sacrificial layer a plurality of number of times;
etching the stacked structure to form a stepped structure on the stacked structure;
forming a second sacrificial layer on the first sacrificial layer;
forming a third sacrificial layer on the second sacrificial layer;
densifying the third sacrificial layer;
etching at least a portion of a sacrificial word line structure including the first sacrificial layer, the second sacrificial layer, and the third sacrificial layer;
forming an interlayer insulation layer on the sacrificial word line structure;
removing the sacrificial word line structure; and
forming a conductive word line structure corresponding to the sacrificial word line structure.
20. A method of processing a substrate, the method comprising:
forming a first silicon nitride layer on a stepped structure having an upper surface, a lower surface, and a side surface that connects the upper surface to the lower surface;
forming a second silicon nitride layer on the first silicon nitride layer;
selectively densifying the second silicon nitride layer; and
performing a wet etching process on the first silicon nitride layer and the second silicon nitride layer,
wherein, during the wet etching process, an etch rate of a portion of a nitride layer on the side surface is greater than an etch rate of portions of a nitride layer on the upper and lower surfaces.
21. A method of processing a substrate, the method comprising:
forming at least one layer on a stepped structure having an upper surface, a lower surface, and a side surface that connects the upper surface to the lower surface;
selectively densifying, via asymmetric plasma application, portions of the at least one layer respectively on the upper surface and the lower surface except for the side surface; and
performing an isotropic etching process on the at least one layer,
wherein, during the isotropic etching process, the portion of the at least one layer formed on the upper surface is separated from the portion of the at least one layer formed on the lower surface.