Process for inhibiting oxide formation on copper surfaces

Abstract

This invention provides processes for inhibiting the formation of copper oxides on substantially oxide-free copper surfaces by contacting a substantially oxide-free copper surface with a bifunctional ligand that contains both a metal-coordinating group and a tertiary amine group in an aqueous solution of pH about 2 to about 5.5. A thin layer of the bifunctional ligand formed by coordination of the dialkylaminoacetonitrile to the copper surface can be removed by heating under vacuum to re-generate a substantially oxide-free copper surface.

1 . A process comprising contacting a substantially oxide-free copper surface with an aqueous solution comprising a bifunctional ligand for a sufficient period of time to form a copper surface coated with a layer of the bifunctional ligand, wherein the bifunctional ligand comprises a nitrile group and a tertiary amine group attached to a carbon atom adjacent to the nitrile group, and the pH of the solution is about 2 to about 5.5. 
     
     
         2 . The process of  claim 1  wherein the layer of bifunctional ligand is from about 5 to about 50 Angstroms thick. 
     
     
         3 . The process of  claim 1 , wherein the aqueous solution further comprises one or more additives selected from the group consisting of chelating agents, corrosion-inhibiting compounds, surface-active agents, organic solvents, fluorides, fluoride equivalents, anti-corrosive agents, and surfactants. 
     
     
         4 . The process of  claim 1 , further comprising rinsing and/or drying the coated copper surface. 
     
     
         5 . The process of  claim 4 , further comprising heating the coated copper surface at 100-300° C. for 5-120 seconds to remove the organic film and to yield an oxide-free copper surface. 
     
     
         6 . The process of  claim 1 , wherein the bifunctional ligand is dimethylaminoacetonitrile or diethylaminoacetonitrile. 
     
     
         7 . A composition comprising:
 (a) a bifunctional ligand in an aqueous solution, the bifunctional ligand comprising a nitrile group and a tertiary amine group attached to a carbon adjacent to the nitrile group; and   (b) sufficient acid so that the pH of the aqueous solution is between about 2 and about 5.5.   
     
     
         8 . A composition comprising:
 (a) a bifunctional ligand in an aqueous solution, the bifunctional ligand comprising a moiety represented by   
       
         
           
           
               
               
           
         
         where R 1  and R 2  are independently selected from methyl and ethyl; and 
         (b) sufficient acid so that the pH of the aqueous solution is between about 2 and about 5.5.