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The present invention provides methods of selectively depositing refractory metal and metal nitride cap layers onto copper lines inlaid in a dielectric layer. The methods result in formation of a cap layer on the copper lines without significant formation on the surrounding dielectric material. The

The present invention provides methods of selectively depositing refractory metal and metal nitride cap layers onto copper lines inlaid in a dielectric layer. The methods result in formation of a cap layer on the copper lines without significant formation on the surrounding dielectric material. The methods typically involve exposing the copper lines to a nitrogen-containing organo-metallic precursor and a reducing agent under conditions that the metal or metal nitride layer is selectively deposited. In a particular embodiment, an amino-containing tungsten precursor is used to deposit a tungsten nitride layer. Deposition methods such as CVD or ALD may be used.

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1. A method of forming a capping layer on copper lines of a semiconductor device, the method comprising: (a) providing a partially fabricated semiconductor device comprising exposed surfaces of the copper lines and surrounding dielectric to a reactor;(b) introducing a vapor phase nitrogen-containing

1. A method of forming a capping layer on copper lines of a semiconductor device, the method comprising: (a) providing a partially fabricated semiconductor device comprising exposed surfaces of the copper lines and surrounding dielectric to a reactor;(b) introducing a vapor phase nitrogen-containing organo-metallic precursor and a reducing agent to the reactor; and(c) exposing the partially fabricated semiconductor device to the organo-metallic precursor and reducing agent under conditions such that a metal nitride film is selectively deposited on the exposed copper lines. 2. The method of claim 1 wherein the organo-metallic precursor and reducing agent are introduced alternately over the substrate to deposit the metal nitride by atomic layer deposition (ALD). 3. The method of claim 2 wherein introducing the reducing agent comprises exposing the agent to a plasma, wherein the plasma is within the deposition chamber or located remotely from the deposition chamber. 4. The method of claim 1, wherein the metal nitride film is deposited by chemical vapor deposition (CVD). 5. The method of claim 1 wherein the precursor is an organo-metallic compound comprising N-substituted amino and imino groups. 6. The method of claim 1 wherein the organo-metallic precursor is an organo-tungsten precursor and the metal nitride film is a tungsten nitride film. 7. The method of claim 6 wherein the organo-tungsten precursor has the structure: wherein each R group is independently selected from methyl, ethyl, propyl, butyl and tert-butyl. 8. The method of claim 6 wherein the organo-tungsten precursor has the following structure: 9. The method of claim 1 wherein the reducing agent is selected from a silane, a borane, ammonia and hydrogen. 10. The method of claim 1 wherein the organo-metallic precursor is an organo-tantalum precursor and the metal nitride film is a tantalum nitride film. 11. The method of claim 10 wherein the precursor is selected from tert-butylimino tris(diethylamino) tantalum (“TBTDET”) and pentakis di-methyl amino tantalum (“PDMAT”). 12. The method of claim 1 further comprising depositing a silicon-containing capping layer over the metal nitride. 13. The method of claim 1, wherein the copper surface is cleaned by an in-situ hydrogen plasma, in-situ dry cleaning or by wet cleaning before depositing the metal nitride. 14. The method of claim 1, wherein the metal nitride layer is between about 3 angstroms and 100 angstroms thick. 15. The method of claim 1, wherein the copper surface is exposed to an in-situ hydrogen plasma before depositing the metal nitride film. 16. A method of forming a capping layer on copper lines of a semiconductor device, the method comprising: providing a partially fabricated semiconductor device comprising exposed surfaces of the copper lines and surrounding dielectric to a reactor;exposing the exposed surfaces of the copper lines to a hydrogen plasma;introducing a vapor phase nitrogen-containing organo-metallic precursor and a reducing agent to the reactor; andexposing the partially fabricated semiconductor device to the organo-metallic precursor and reducing agent under conditions such that a metal nitride film is selectively deposited on the exposed copper lines.