Methods of etching metal oxides with less etch residue
Processing methods to etch metal oxide films with less etch residue are described. The methods comprise etching a metal oxide film with a metal halide etchant, and exposing the etch residue to a reductant to remove the etch residue. Some embodiments relate to etching tungsten oxide films. Some embodiments utilize tungsten halides to etch metal oxide films. Some embodiments utilize hydrogen gas as a reductant to remove etch residues.
1. A substrate processing method comprising:
exposing a substrate comprising an oxidized metal layer to a metal halide to etch a portion of the oxidized metal layer and produce an etch residue; and
exposing the substrate to a reductant to remove the etch residue.
2. The method of claim 1 , wherein an average oxidation state of the oxidized metal layer is less than an average oxidation state of a stoichiometric metal oxide.
3. The method of claim 2 , wherein the oxidized metal layer comprises a sub-stoichiometric metal oxide.
4. The method of claim 2 , wherein the metal oxide comprises one or more of N, Si, or C.
5. The method of claim 1 , wherein the oxidized metal layer and the metal halide comprise the same metal species.
6. The method of claim 1 , wherein the oxidized metal layer comprises tungsten (W).
7. The method of claim 1 , wherein the metal halide comprises tungsten (W).
8. The method of claim 7 , wherein the metal halide consists essentially of WF 6 .
9. The method of claim 7 , wherein the metal halide consists essentially of WCl 5 .
10. The method of claim 1 , wherein the reductant comprises one or more of H 2 , B 2 H 6 or BCl 3 .
11. The method of claim 1 , further comprising repeating the exposure to the metal halide and exposure to the reductant.
12. The method of claim 1 , wherein the substrate processing method is performed at a pressure of greater than or equal to about 5 torr.
13. The method of claim 1 , wherein the substrate is maintained at a temperature of less than or equal to about 400° C.
14. A substrate processing method comprising:
(A) providing a substrate comprising an oxidized metal layer in a processing chamber with a processing volume;
(B) exposing the substrate to a metal halide to remove a portion of the oxidized metal layer and produce an etch residue;
(C) exposing the substrate to a reductant to remove the etch residue; and
(D) repeating (B) and (C) until a predetermined thickness of the oxidized metal layer has been removed.
15. The method of claim 14 , further comprising purging the processing volume after exposing the substrate to the metal halide and purging the processing volume after exposing the substrate to the reductant.
16. The method of claim 14 , wherein an average oxidation state of the oxidized metal layer is less than an average oxidation state of a stoichiometric metal oxide.
17. The method of claim 14 , wherein the oxidized metal layer comprises WO 3 .
18. The method of claim 14 , wherein the metal halide comprises one or more of WF 6 or WCl 5 .
19. The method of claim 14 , wherein the reductant comprises one or more of H 2 , B 2 H 6 or BCl 3 .
20. A substrate processing method comprising:
(A) providing a substrate comprising a WO 3 layer in a processing chamber with a processing volume;
(B) exposing the substrate to a etchant comprising one or more of WF 6 or WCl 5 to remove a portion of the WO 3 layer and produce an etch residue;
(C) purging the processing volume with an inert gas;
(D) exposing the substrate to a reductant comprising H 2 to remove the etch residue;
(E) purging the processing volume with an inert gas; and
(F) repeating (B) through (E) until a predetermined thickness of the WO 3 layer has been removed.