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:
oxidizing a metal layer within a feature in a substrate to produce an oxidized metal layer, the feature lined with a barrier layer having a thickness in a range of about 0.5 nm to about 10 nm;
exposing the substrate comprising the 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 substantially no oxygen.
4. The method of claim 1 , wherein the method is plasma free.
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 metal layer comprises one or more of Co, Mo, W, Ta, Ti, Ru, Rh, Cu, Fe, Mn, V, Nb, Hf, Zr, Y, Al, Sn, Cr, or La.
7. The method of claim 1 , wherein the barrier layer is a nitride.
8. The method of claim 1 , wherein the barrier layer is an oxide.
9. The method of claim 1 , wherein the barrier layer comprises one or more of AlO, TiO 2 , TiN, TaN, SiN, Ti or Ta.
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 oxidizing the metal layer within the feature forms an additional layer on the surface of the substrate outside of the feature.
13. A substrate processing method comprising:
(A) oxidizing a metal layer within a feature of a substrate in a processing chamber with a processing volume to form an oxidized metal layer within the feature, the oxidized metal layer comprising substantially no oxygen;
(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.
14. The method of claim 13 , 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.
15. The method of claim 13 , wherein an average oxidation state of the oxidized metal layer is less than an average oxidation state of a stoichiometric metal oxide.
16. The method of claim 13 , wherein the feature is lined with a barrier layer.
17. The method of claim 13 , wherein the metal halide comprises one or more of WF 6 or WCl 5 .
18. The method of claim 13 , wherein the reductant comprises one or more of H 2 , B 2 H 6 or BCl 3 .
19. A substrate processing method comprising:
(A) oxidizing a tungsten layer on a substrate within a processing chamber with a processing volume to form a WO 3 layer;
(B) exposing the substrate to a etchant 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,
wherein the method is plasma free.