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, the method comprising one or more etching cycles, each etching cycle comprising:
exposing the substrate to a vapor-phase halide reactant; and
purging or evacuating the reaction chamber to remove excess vapor-phase halide reactant, wherein the vapor-phase halide reactant comprises at least one halide ligand and 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 , wherein the film comprises a metal.
3. The method of claim 1 , wherein the film comprises a metal sulfide, a metal oxide, a metal carbide, or a metal nitride.
4. The method of claim 1 , wherein the film comprises Si or Ge.
5. The method of claim 1 , wherein the film comprises TiN, TiOx, TaN, AlOx, ZrOx, AlN, Cu, Co, CuOx, CoOx, Mo, W, MoOx, LaOx, or HfOx.
6. The method of claim 1 , wherein the halide reactant comprises a carbon based alkyl halide.
7. The method of claim 1 , wherein the halide reactant comprises an oxyhalide.
8. The method of claim 1 , wherein the halide reactant comprises CCl 4 , CHCl 3 , CCl 3 Br, CCl 2 Br 2 or CHCl 5 .
9. The method of claim 1 , wherein the halide reactant comprises a semi-metal halide.
10. The method of claim 1 , wherein the halide reactant comprises a semi-metal oxyhalide.
11. The method of claim 1 , wherein the substrate comprises two films that are exposed to the vapor-phase halide reactant and one film is selectively etched relative to the other.
12. The method of claim 1 , wherein the temperature of the substrate during the etching cycle is 150° C. to 600° C.
13. The method of claim 1 , wherein the substrate is exposed to the vapor-phase halide reactant for 0.01 s to 100 s.
14. The method of claim 1 , wherein exposing the substrate to the vapor phase halide reactant comprises flowing the vapor-phase halide reactant continuously into the reaction chamber.
15. The method of claim 1 , wherein exposing the substrate to the vapor phase halide reactant comprises flowing the vapor-phase halide reactant intermittently into the reaction chamber.
16. The method of claim 1 , wherein the pressure in the reaction chamber is between 10E-9 torr and 760 torr during the etching cycle.
17. The method of claim 1 , wherein the etching cycle is repeated two or more times in a row.
18. The method of claim 1 , wherein the substrate is not contacted with HF during the etching cycle.
19. The method of claim 1 , further comprising contacting the substrate with a second vapor-phase reactant in the etching cycle.
20. The method of claim 19 , wherein the second vapor-phase reactant comprises CH y Cl x , CCl 4 , trimethylaluminum, SO 3 , H 2 O, O 2 , O 3 , H 2 O 2 or nitrogen oxide.