Electroless copper plating of electronic device components

Abstract

A method and composition for improving the deposition plating rate of electroless copper. The invention presents embodiments comprising using elevated plating temperatures at the substrate-solution interface. This is coupled with suitably designed bath compositions, to preserve the electroless bath stability, required to improve the deposition plating rate of electroless copper. In one embodiment, the electroless bath composition comprises suitable individual Cu ++ and Cu + complexing agent(s), or a combination of complexing agents, surfactants, organic polymer additives, and the like, adapted and suitably optimized. For example, potential organic additive types or surfactants can be Polyoxes; Pluronics; Polyols; Polyglycols; Carbowaxes; Hydroxy ethyl cellulose (HEC), carboxy acetylenic, or fluocarbon acetylenic surfactants. The method and composition of the present invention enable the production of electroless copper coatings with improved adhesion to the substrate. This is achieved by selecting activation systems that result in copper initiation at moderate rates. An electroless copper composition assists, in that it too, ensures slow initial copper reduction at the substrate-solution interface.

I claim:  
     
         1 . A composition for electroless plating of copper on a substrate, comprising copper ions, a complexing agent for Cu ++  ions, a complexing agent for Cu +  ions, a reducing agent capable of reducing copper ions to metallic copper and hydroxide ions to a pH of at least 10.  
     
     
         2 . A composition for electroless plating of copper on a substrate, comprising copper ions, a mixture of complexing agents for Cu ++  ions, a mixture of complexing agents for Cu +  ions, a reducing agent capable of reducing copper ions to metallic copper and hydroxide ions to a pH of at least 10.  
     
     
         3 . A composition according to  claim 1 , wherein said agent that forms a complex with Cu ++  ions is selected from a group consisting of EDTA, Quadrol and mixtures thereof.  
     
     
         4 . A composition according to  claim 1 , wherein said agent that forms a complex with Cu +  ions is selected from a group consisting of derivatives of pyridine, alkali metal cyanides, cyanates and heavy metal cyanide complexes.  
     
     
         5 . A composition according to  claim 4 , comprising at least 10 ppm of said agent that forms a complex with Cu +  ions.  
     
     
         6 . A composition according to  claim 4 , comprising at least 20 ppm of bipyridine.  
     
     
         7 . A composition according to  claim 1 , further comprising at least one surfactant.  
     
     
         8 . An improved method for electroless plating of copper on a substrate using an electroless composition according to  claim 1 .  
     
     
         9 . An improved method for electroless plating of copper on a substrate using an electroless composition according to  claim 2 .  
     
     
         10 . A method according to  claim 8 , further comprising heating the substrate to a temperature above the operating temperature of the electroless plating bath.  
     
     
         11 . A method according to  claim 10 , wherein at least part of the surface of said substrate is non-metallic.  
     
     
         12 . A method according to  claim 8 , wherein the substrate is flat.  
     
     
         13 . A method according to  claim 9 , wherein the substrate is flat.  
     
     
         14 . A method according to  claim 8 , wherein the substrate is made of 
 material selected from a group consisting of copper-clad polymer and silicon material.    
     
     
         15 . A method according to  claim 14 , wherein the substrate comprises vias and trenches.  
     
     
         16 . An article manufactured by the method of  claim 8 .  
     
     
         17 . An article manufactured by the method of  claim 9 .  
     
     
         18 . An article manufactured by the method of  claim 10 .  
     
     
         19 . An article manufactured by the method of  claim 11.