Methods of etching films comprising transition metals
Provided are methods for etching films comprising transition metals. Certain methods involve activating a substrate surface comprising at least one transition metal, wherein activation of the substrate surface comprises exposing the substrate surface to heat, a plasma, an oxidizing environment, or a halide transfer agent to provide an activated substrate surface; and exposing the activated substrate surface to a reagent comprising a Lewis base or pi acid to provide a vapor phase coordination complex comprising one or more atoms of the transition metal coordinated to one or more ligands from the reagent. Certain other methods provide selective etching from a multi-layer substrate comprising two or more of a layer of Co, a layer of Cu and a layer of Ni.
1. A method of etching a substrate, the method comprising:
activating a substrate surface comprising a transition metal, wherein activation of the substrate surface comprises exposing the substrate surface to heat, a plasma, an oxidizing environment, or a halide transfer agent to provide an activated substrate surface; and
exposing the activated substrate surface to a reagent comprising a Lewis base or pi acid to provide a vapor phase coordination complex comprising one or more atoms of the transition metal coordinated to one or more ligands from the reagent
wherein the Lewis base or pi acid comprises a chelating amine selected from the group consisting of N,N,N′,N′-tetramethylethylene diamine, ethylene diamine, N,N′-dimethylethylenediamine, 2-(aminomethyl)pyridine, 2- [(alkylamino)methyl]pyridine, and 2-[(dialkylamino)methyl]pyridine, wherein the alkyl group is C1-C6 alkyl.
2. The method of claim 1 , wherein activation of the substrate surface comprises exposing the substrate surface to heat.
3. The method of claim 2 , wherein exposure of the substrate surface to heat and the reagent occur sequentially or substantially sequentially.
4. The method of claim 1 , wherein activation of the substrate surface comprises exposing the substrate surface to a plasma.
5. The method of claim 4 , wherein the plasma comprises H 2 , NO, N 2 O, NF 3 , Cl 2 , Ar or N 2 .
6. The method of claim 5 , wherein the plasma comprises N 2 O, and exposure of the substrate surface to the N 2 O results in a —NO surface termination.
7. The method of claim 1 , wherein activation of the substrate surface comprises exposure to a halide transfer agent.
8. The method of claim 1 , wherein exposure of the substrate surface to an oxidizing environment comprises exposing the substrate surface to O 2 , O 3 , N 2 O, NO, Br 2 , F 2 , I 2 or Cl 2 .
9. The method of claim 1 , wherein the substrate surface comprises about 90 to about 100% transition metal and 0 to about 10% carbon.
10. The method of claim 1 , wherein the substrate surface overlies a deposition chamber wall or showerhead.
11. The method of claim 1 , wherein the transition metal comprises an element selected from the group consisting of Co, Ru, Ni, Fe, Mn and Pd.
12. A method of etching a multi-layer substrate, the method comprising:
providing a multi-layer substrate comprising two or more of a layer of Co, a layer of Cu and a layer of Ni;
activating a surface of the layer of Co, layer of Cu or layer of Ni, wherein activation of the substrate surface comprises exposing the substrate surface to heat, a plasma or a halide transfer agent to provide an activated substrate surface; and
exposing the activated substrate surface to a chelating amine at a first temperature such that the chelating amine will only form a volatile metal coordination complex with one of Co, Cu or Ni at the first temperature.
13. The method of claim 12 , further comprising exposing the activated substrate surface to a chelating amine at a second temperature, such that the chelating amine will only form a volatile metal coordination complex with one of Co, Cu or Ni at the second temperature.
14. The method of claim 10 , wherein the chelating amine has a structure represented by:
wherein each R a is independently hydrogen or C1-C4 alkyl, with the proviso that not all of the R a groups are hydrogen.
15. The method of claim 14 , wherein the chelating amine is selected from the group consisting of N,N,N′,N′-tetramethylethylene diamine and N,N′-dimethylethylenediamine.
16. The method of claim 15 , further comprising purging the coordination complex.
17. A method of etching a substrate, the method comprising:
activating a substrate surface comprising cobalt or copper, wherein activation of the substrate surface comprises exposing the substrate surface to Br 2 to provide an activated substrate surface; and
exposing the activated substrate surface to a reagent comprising TMEDA to provide a vapor phase coordination complex comprising one or more atoms of the cobalt or copper coordinated to one or more ligands from the reagent.