Atomic layer etching processes
Atomic layer etching (ALE) processes are disclosed. In some embodiments, the methods comprise at least one etch cycle in which the substrate is alternately and sequentially exposed to a first vapor phase non-metal halide reactant and a second vapor phase halide reactant. In some embodiments both the first and second reactants are chloride reactants. In some embodiments the first reactant is fluorinating gas and the second reactant is a chlorinating gas. In some embodiments a thermal ALE cycle is used in which the substrate is not contacted with a plasma reactant.
1. A method of etching a film on a substrate in a reaction chamber by chemical atomic layer etching, the method comprising one or more etching cycles comprising:
exposing the substrate to a first vapor-phase oxyhalide reactant; and
purging or evacuating the reaction chamber to remove excess first vapor-phase oxyhalide halide reactant, wherein the first vapor-phase oxyhalide reactant does not comprise metal, wherein the substrate is not contacted with a plasma reactant during the etching cycle, and wherein each etching cycle removes material from the film.
2. The method of claim 1 , further comprising exposing the substrate to a vapor-phase metal or semi-metal halide reactant.
3. The method of claim 2 , wherein the vapor-phase metal or semi-metal halide reactant comprises Te, Sb, As, Nb, Ta, Mo, Sn, V, Re, Te, W or a group 6 transition metal.
4. The method of claim 2 , wherein the vapor phase metal or semi-metal halide reactant comprises sulfur atoms.
5. The method of claim 2 , wherein the vapor phase metal or semi-metal halide reactant comprises oxygen atoms.
6. The method of claim 1 wherein the first vapor phase oxyhalide reactant comprises carbon, oxygen and halide atoms.
7. The method of claim 1 , further comprising exposing the substrate to a second vapor-phase oxyhalide reactant.
8. The method of claim 7 , wherein the etch cycle additionally comprises exposing the substrate to a third vapor-phase reactant that is different from the first and second vapor-phase oxyhalide reactants.
9. The method of claim 8 , where the third vapor-phase reactant comprises oxygen.
10. The method of claim 8 , wherein the third vapor-phase reactant comprises H 2 O 2 , HCOOH, H 2 O, O 2 or O 3 .
11. The method of claim 8 , where the third vapor-phase reactant comprises a ligand exchanger.
12. The method of claim 8 , wherein the third vapor-phase reactant comprises trimethylaluminum (TMA), Hacac, Sn(acac) 2 , or Hhfac.
13. The method of claim 8 , where the third vapor phase reactant comprises an adduct forming compound.
14. The method of claim 8 , wherein the third vapor phase reactant comprises CS 2 , CH 3 CN, NH 3 , SO 3 , tris(2-aminoethyl)amine, triethanolamine, pyridine, tetrahydrofuran (THF), dimethylsulfoxide (DMSO), tetrahydrothiophene, 1, 4-dioxane, an isocyanate, a poly-ol, ethanolamine, a sulfone, trichloromethane, an alkyl or substituted isothiocyanate, trichloronitromethane, an alkyl, aryl or substituted nitrile, an isonitrile, a diamine, a dithione, a sulfone, TIPA, TIPEA, TMEA or a heterocylic reactive compound.
15. The method of claim 1 , wherein the first vapor-phase oxyhalide reactant comprises a semi-metal.
16. The method of claim 1 , wherein the first vapor-phase oxyhalide reactant does not comprise carbon.
17. The method of claim 1 , wherein the first vapor-phase oxyhalide reactant does not comprise a hydrocarbon group.
18. The method of claim 1 , wherein the first vapor-phase oxyhalide reactant does not comprise hydrogen.
19. The method of claim 1 , wherein the first vapor-phase oxyhalide reactant does not comprise hydrogen or carbon.
20. The method of claim 1 , wherein the first vapor-phase oxyhalide reactant comprises sulfur, halide and oxygen atoms.
21. The method of claim 1 , wherein the first vapor-phase oxyhalide reactant comprises halide and nitrogen atoms.
22. The method of claim 1 , wherein the first vapor-phase oxyhalide reactant comprises sulfur, halide and nitrogen atoms.
23. The method of claim 1 , wherein the first vapor-phase oxyhalide reactant comprises sulfur, halide, oxygen and nitrogen atoms.
24. The method of claim 1 , wherein the first vapor-phase oxyhalide reactant comprises of sulfur, halide, carbon and nitrogen atoms.
25. The method of claim 1 , wherein the first vapor-phase oxyhalide reactant comprises of sulfur, halide, carbon, oxygen and nitrogen atoms.
26. The method of claim 1 , wherein the substrate comprises two or more different materials that are exposed to the first vapor-phase oxyhalide reactant and one material is selectively etched relative to the other materials.
27. The method of claim 1 , wherein the film comprises a metal oxide, metal carbide, metal nitride or is an elemental film.
28. The method of claim 27 , wherein the film comprises Ti, Mo, Cu, Co, W, Si, Ta, Al, Zr, Hf, Ge, Pt, Ni, Zn, Nb 1 r, Ru, Rh, or Sb.
29. The method of claim 1 , wherein the temperature of the substrate during the etching cycle is 150° C. to 600° C.
30. The method of claim 1 , wherein the substrate is a semiconductor wafer.
31. The method of claim 1 , wherein the method has an average etch rate of 0.01 to 5 A/cycle.