Methods of etching films with reduced surface roughness
Provided are methods for etching films comprising transition metals which help to minimize higher etch rates at the grain boundaries of polycrystalline materials. Certain methods pertain to amorphization of the polycrystalline material, other pertain to plasma treatments, and yet other pertain to the use of small doses of halide transfer agents in the etch process.
1. A method of etching a substrate, the method comprising:
providing a polycrystalline film comprising a transition metal;
amorphizing at least a portion of the polycrystalline film to provide an amorphous layer;
exposing the amorphous layer to 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.
2. The method of claim 1 , wherein the Lewis base or pi acid comprises CO, PR 1 3 , wherein each R 1 is independently a C1-C6 alkyl group, 1,2-bis(difluorophosphino)ethane, N 2 O, NO, NH 3 , NR 2 3 , wherein each R 2 is independently hydrogen C1-C6 branched or unbranched, substituted or unsubstituted, alkyl, allyl or cyclic hydrocarbon or heteroatomic group, or a compound having the structure:
wherein each R b is independently hydrogen, R or C1-C4 alkyl.
3. The method of claim 1 , wherein the pi acid comprises AlH n X m R c p , wherein X is a halogen, the sum of n+m+p is 3, and R c is C1-C6 alkyl.
4. The method of claim 1 , 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.
5. The method of claim 1 , wherein the halide transfer agent is selected from the group consisting of Cl 2 and Br 2 .
6. The method of claim 1 , wherein the polycrystalline film comprises cobalt.
7. The method of claim 1 , wherein the polycrystalline film comprises a metal selected from the group consisting of Co, Cu, Ru, Ni, Fe, Pt, Mn and Pd.
8. The method of claim 1 , wherein amorphization comprises exposing the polycrystalline film to a plasma.
9. The method of claim 1 , wherein exposing the amorphous layer to the halide transfer agent and exposing the activated substrate surface to the reagent etches the amorphous layer, and the amorphous layer is partially etched.
10. The method of claim 1 , wherein exposing the amorphous layer to the halide transfer agent and exposing the activated substrate surface to the reagent etches the amorphous layer, and the amorphous layer is substantially etched.
11. The method of claim 1 , further comprising repeating exposing the amorphous layer to the halide transfer agent and exposing the activated substrate surface to the reagent.
12. A method of etching a substrate, the method comprising:
providing a polycrystalline film comprising a transition metal;
exposing the polycrystalline film to an inert plasma, reducing gas or reagent vapor;
exposing the polycrystalline film to 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.
13. The method of claim 12 , wherein the Lewis base or pi acid comprises CO, PR 1 3 , wherein each R 1 is independently a C1-C6 alkyl group, 1,2-bis(difluorophosphino)ethane, N 2 O, NO, NH 3 , NR 2 3 , wherein each R 2 is independently hydrogen C1-C6 branched or unbranched, substituted or unsubstituted, alkyl, allyl or cyclic hydrocarbon or heteroatomic group, or a compound having the structure:
wherein each R b is independently hydrogen, R or C1-C4 alkyl.
14. The method of claim 12 , wherein the pi acid comprises AlH n X m R c p , wherein X is a halogen, the sum of n+m+p is 3, and R c is C1-C6 alkyl.
15. The method of claim 14 , 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.
16. The method of claim 12 , wherein the halide transfer agent is selected from the group consisting of Cl 2 and Br 2 .
17. The method of claim 12 , wherein the polycrystalline film comprises cobalt.
18. The method of claim 12 , wherein the polycrystalline film comprises a metal selected from the group consisting of Co, Cu, Ru, Ni, Fe, Pt, Mn and Pd.
19. A method of etching a substrate, the method comprising:
activating a substrate surface comprising a polycrystalline film of a metal selected from the group consisting of Co, Cu, Ru, Ni, Fe, Pt, Mn and Pd, wherein activation of the substrate surface comprises exposing the substrate surface to Br 2 or Cl 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 Co, Cu, Ru, Ni, Fe, Pt, Mn or Pd coordinated to one or more ligands from the reagent,
wherein the Br 2 is present in an amount effective to etch about one Angstrom of the substrate surface.