CMP method for gold-containing substrates

Abstract

The invention provides a method of chemically-mechanically polishing a gold-containing surface of a substrate with a cyanide-free chemical-mechanical polishing (CMP) composition.

1 . A method for polishing a gold substrate comprising:
 (a) contacting a gold-containing surface of a substrate with a polishing pad and a cyanide-free CMP composition for a time period sufficient to oxidize gold on the surface of the substrate, the CMP composition comprising an abrasive, a gold-oxidizing agent, a cyanide-free gold-solubilizing agent, and an aqueous carrier; and   (b) causing relative motion between the pad and the surface while maintaining a portion of the CMP composition in contact with the surface between the pad and the substrate for a time period sufficient to abrade the oxidized portion of the surface with the CMP composition.   
   
   
       2 . The method of  claim 1  wherein the gold oxidizing agent is present in the composition at a concentration in the range of about 0.5% to about 6% on a weight basis. 
   
   
       3 . The method of  claim 1  wherein the CMP composition has a basic pH and the gold-oxidizing agent comprises a persulfate salt. 
   
   
       4 . The method of  claim 1  wherein the CMP composition has an acidic pH and gold-oxidizing agent comprises a halogen. 
   
   
       5 . The method of  claim 1  wherein the CMP composition has an acidic pH and the gold-oxidizing agent comprises a reactive admixture of an oxyhalogen compound and a halide salt. 
   
   
       6 . The method of  claim 1  wherein the cyanide-free gold-solubilizing agent is present in the composition at a concentration in the range of about 0.5% to about 6% on a weight basis. 
   
   
       7 . The method of  claim 1  wherein the cyanide-free gold-solubilizing agent comprises a phosphonic acid chelating agent, a salt thereof, or a combination thereof. 
   
   
       8 . The method of  claim 1  wherein the CMP composition has a basic pH, the gold-oxidizing agent comprises ammonium persulfate, and the cyanide-free gold-solubilizing agent comprises a phosphonic acid chelating agent, a salt thereof, or a combination thereof. 
   
   
       9 . The method of  claim 1  wherein the abrasive is present in the composition at a concentration in the range of about 0.5% to about 3% on a weight basis. 
   
   
       10 . The method of  claim 1  wherein the abrasive comprises alpha-alumina. 
   
   
       11 . A method for polishing a gold substrate comprising:
 (a) contacting a gold-containing surface of a substrate with a polishing pad and a cyanide-free CMP composition for a time period sufficient to oxidize gold on the surface of the substrate, the CMP composition comprising an abrasive, an oxyhalogen compound, a halide salt, and an aqueous carrier; and   (b) causing relative motion between the pad and the surface while maintaining a portion of the CMP composition in contact with the surface between the pad and the substrate for a time period sufficient to abrade the oxidized portion of the surface with the CMP composition,   wherein the oxyhalogen compound and the halide salt are kept separate from one another and are admixed just prior to contacting the surface of the substrate, or are admixed on the surface of the substrate.