Etching method, substrate processing apparatus, and substrate processing system

1. An etching method, comprising:

(a) forming a film on a surface of a substrate, wherein the substrate includes layer to be etched and a mask, the mask is provided on the layer and in direct contact with the layer, the film is formed directly on a top surface of the mask so that the mask is between the film and the layer, the mask includes an opening that partially exposes the layer, the layer has an opening having a first depth, and the film is made of a same material as that of the layer; and

(b) etching the layer after the forming the film to etch the layer to a second depth deeper into the layer than the first depth.

2. The etching method according to claim 1 , wherein during the etching the layer, an etching rate of etching the film divided by an etching rate of etching the layer is from 0.7 to 1.2.

3. The etching method according to claim 1 , wherein the layer is made of an organic material.

4. The etching method according to claim 1 , wherein the layer is made of silicon oxide or silicon nitride.

5. The etching method according to claim 1 , wherein the layer includes a plurality of layers made of two or more materials from silicon oxide, silicon nitride, and polycrystalline silicon, respectively.

6. The etching method according to claim 1 , wherein the layer is made of silicon, germanium, or both silicon and germanium.

7. The etching method according to claim 6 , wherein the film is made of amorphous silicon.

8. The etching method according to claim 1 , wherein the layer is made of a low-dielectric material.

9. The etching method according to claim 1 , further comprising:

during the forming the film or prior to the forming the film, partially etching into a depth of the layer; and

after the forming the film, further etching the layer in (b) to increase the depth of an opening in the layer.

10. The etching method according to claim 1 , wherein the forming of the film includes:

forming a precursor layer on the substrate by supplying a first gas to the substrate; and

forming the film on the substrate from the precursor layer either by supplying a second gas to the precursor layer or by activating the precursor layer.

11. The etching method according to claim 10 , wherein the film is formed using chemical species from plasma generated from the second gas.

12. The etching method according to claim 1 , wherein the film is formed by chemical vapor deposition (CVD).

13. The etching method according to claim 1 , wherein the film is formed such that a thickness thereof decreases along a depth in the substrate from a top edge of the substrate.

14. The etching method according to claim 1 , wherein prior to the forming the film, the opening of the mask has a width which is 100 nm or less.

15. The etching method according to claim 1 , further comprising alternately repeating (a) and (b).

16. The etching method according to claim 1 , wherein the forming the film includes forming the film on sidewalls of the opening of the mask, and on sidewalls and a bottom of the opening of the layer having the first depth.

17. An etching method, comprising:

providing a substrate having a layer to be etched and a mask on the layer and in direct contact with the layer, the mask having an opening which partially exposes the layer, the layer having an opening having a first depth, the substrate further including an underlying layer below the layer, with the underlying layer being composed of a different material than a material of the layer:

forming a film on a top surface of the mask so that the mask is between the film and layer, the film being formed on at least one of a side wall of the opening of the mask or a portion of the layer exposed through the mask, and the film includes a same material as the material of the layer; and

after the forming the film, etching the layer through the opening in the mask to etch the layer to a second depth deeper into the layer than the first depth.

18. The etching method according to claim 17 , further comprising:

prior to the forming the film, partially etching the layer through the opening in the mask to etch the first depth in the layer.

19. The etching method according to claim 18 , wherein

the forming the film includes forming the film on sidewalls of the opening of the mask and on sidewalls of an opening of the layer etched during the etching prior to the forming the film, and

the etching of the layer after forming of the film exposes the underlying layer.

20. The etching method according to claim 18 , wherein during the etching the layer, an etching rate of etching the film divided by an etching rate of etching the layer is from 0.7 to 1.2.