Selective formation of metallic films on metallic surfaces
Metallic layers can be selectively deposited on one surface of a substrate relative to a second surface of the substrate. In some embodiments, the metallic layers are selectively deposited on copper instead of insulating or dielectric materials. In some embodiments, a first precursor forms a layer on the first surface and is subsequently reacted or converted to form a metallic layer. The deposition temperature may be selected such that a selectivity of above about 50% or even about 90% is achieved.
1. A method for selectively depositing a film on a first metal surface of a substrate relative to a second dielectric surface of the substrate, the method comprising:
cleaning the substrate;
conducting a dielectric restoration step; and
carrying out a plurality of deposition cycles at a temperature of less than 150° C., comprising:
exposing the substrate to a first precursor comprising silicon to form a layer comprising silicon on the first metal surface; and
exposing the substrate to a second precursor comprising a metal selected from Ta, Nb, Ti, and V,
wherein a thin film is selectively deposited on the first metal surface relative to the second dielectric surface and the selectivity is greater than about 50%.
2. The method of claim 1 , wherein cleaning the substrate comprises exposing at least the first metal surface to a plasma.
3. The method of claim 2 , wherein the plasma comprises one or more of Ar, H, and N.
4. The method of claim 1 , wherein cleaning comprises removing a passivation layer from the first metal surface.
5. The method of claim 1 , wherein the dielectric restoration step and the deposition cycles are conducted in different reaction spaces.
6. The method of claim 1 , wherein the dielectric restoration step comprises exposing the substrate to one or more silanes.
7. The method of claim 1 , wherein the dielectric restoration step comprises exposing the substrate to a silane having the formula Si n H 2n+2 , where n is equal to or greater than 1.
8. The method of claim 1 , wherein the dielectric restoration step comprises contacting the second dielectric surface with SiHxLy, where L is selected from alkyl, alkenyl, alkynyl, alkoxide and amide groups.
9. The method of claim 1 , wherein the dielectric restoration step comprises silylation of the second dielectric surface.
10. The method of claim 1 , wherein the dielectric restoration step comprises forming —Si(CH 3 ) 3 groups on the second dielectric surface.
11. The method of claim 1 , wherein the dielectric surface restoration step comprises contacting the substrate with Si 2 H 6 or trimethylchlorosilane.
12. The method of claim 1 , wherein the one or more deposition cycles are carried out prior to conducting the dielectric restoration step.
13. The method of claim 1 , wherein the selectivity is greater than about 90%.
14. The method of claim 1 , additionally comprising annealing the substrate at a temperature from 150° C. to 400° C. prior to conducting the deposition cycles.
15. The method of claim 1 , wherein the thin film is a metal nitride or metal silicide.
16. The method of claim 1 , wherein the thin film is a metallic film.
17. The method of claim 1 , wherein the thin film comprises elemental tungsten.
18. The method of claim 1 , wherein the first metal surface comprises copper.