Thermal atomic layer etching processes
Thermal atomic layer etching 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 halide reactant and a second vapor halide reactant. In some embodiments, the first reactant may comprise an organic halide compound. During the thermal ALE cycle, 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, each etching cycle comprising:
exposing the substrate to a first vapor-phase metal halide reactant to thereby form adsorbed species on the substrate; and
subsequently exposing the substrate to a second vapor-phase reactant, wherein the second vapor-phase reactant converts the adsorbed species into volatile adduct compounds comprising one or more atoms from the film; and
removing volatile adduct compounds from the reaction chamber.
2. The method of claim 1 , additionally comprising exposing the substrate to at least one additional vapor-phase reactant.
3. The method of 1 , wherein the film comprises at least one of W, TiN, TiO 2 , TaN, SiN, AlO 2 , Al 2 O 3 , ZrO 2 , WO 3 , AlN and HfO 2 .
4. The method of claim 1 , wherein the etching cycle is repeated two or more times.
5. The method of claim 1 , wherein the first vapor-phase metal halide reactant comprises NbF 5 .
6. The method of claim 1 , wherein the second vapor-phase reactant comprises a Lewis base.
7. The method of claim 1 , wherein the second vapor-phase reactant comprises pyradine, tetrahydrofuran, DMSO, or tetrahydrothiophene.
8. The method of claim 1 , wherein the substrate being etched comprises a metal nitride such as TiN or TaN and the second vapor-phase reactant comprises a Lewis acid.
9. The method of claim 1 , wherein the second vapor-phase reactant comprises BCl 3 , BF 3 , or AlCl 3 .
10. The method of claim 1 , wherein the second vapor-phase reactant comprises a diamine or dithione.
11. The method of claim 1 , wherein the second vapor-phase reactant comprises a heterocyclic reactive compound.
12. The method of claim 11 , wherein the heterocyclic reactive compound comprises a thiocarbonate, thiadiazoel, or dioxane.
13. The method of claim 1 , wherein the volatile adduct comprises an atrane compound.
14. The method of claim 1 , wherein the second vapor-phase reactant forms coordinated bonds to a metal atom from the first reactant that has adsorbed to the substrate surface.
15. The method of claim 1 , wherein the first reactant comprises NbCl 5 .
16. The method of claim 1 , wherein the second vapor-phase reactant comprises CS 2 .
17. The method of claim 1 , wherein the etching cycle further comprises removing volatile adduct compounds from the reaction chamber.
18. The method of claim 1 , wherein the additional phases are added and removed as desired to adjust the etch rate and/or to influence one or more properties of the remaining film after etching film, such as tune the resistivity.
19. The method of claim 1 , wherein the additional phases can be introduced in before or after supplying the first and second vapor-phase reactants.
20. The method of claim 19 , wherein the first vapor-phase reactant comprises one or more of SeF 4 , SeF 6 , trichloromethanesulfinyl chloride, BF 2 acac, NbF 5 , SbF 5 , TeF 6 , POCl 3 , fumaryl chloride, MoOF 4 , ReOF 4 , ReOF 5 , and fluoroantimony salts.