Method and composition to enhance wetting of ECP electrolyte to copper seed

Abstract

A composition and method which substantially enhances the wetting of an electrolyte solution to a surface in the electrochemical plating of a metal such as copper on the surface. The composition is an organic mixture which includes an organic acid, such as citric acid or acetic acid, and a low molecular weight ionic polymer such as an alcohol, an amine or alkyphenol alkoxylate. The method includes suspending the composition as a layer in the solution and passing the surface through the composition suspension layer to define a wetting layer on the surface. Consequently, metal electroplated onto the surface is substantially devoid of pits or other structural defects.

1 . An electrolyte for copper electroplating, comprising: 
 an electrolyte solution; and    a composition comprising an organic acid and a non-ionic polymer mixed with said organic acid provided in said electrolyte solution.    
     
     
         2 . The electrolyte of  claim 1  wherein said organic acid is citric acid or acetic acid.  
     
     
         3 . The electrolyte of  claim 1  wherein said non-ionic polymer is an alcohol, an amine or alkyphenol alkoxylate.  
     
     
         4 . The electrolyte of  claim 1  wherein said composition is present in said electrolyte solution in a concentration of about 5% by weight.  
     
     
         5 . The electrolyte of  claim 1  wherein said non-ionic polymer has a molecular weight of less than 1,000.  
     
     
         6 . The electrolyte of  claim 5  wherein said organic acid is citric acid or acetic acid.  
     
     
         7 . The electrolyte of  claim 1  wherein said organic acid is present in said composition in a wt. % of about 10, and wherein said ionic polymer is present in said composition in a wt. % of about 5.  
     
     
         8 . The electrolyte of  claim 7  wherein said organic acid is citric acid or acetic acid and said non-ionic polymer is an alcohol, an amine or alkyphenol alkoxylate.  
     
     
         9 . An electrolyte for copper electroplating, comprising: 
 an electrolyte solution; and    a composition comprising an organic acid and a non-ionic polymer mixed with said organic acid provided in a suspension layer in said electrolyte solution.    
     
     
         10 . The electrolyte of  claim 9  wherein said organic acid is citric acid or acetic acid.  
     
     
         11 . The electrolyte of  claim 9  wherein said non-ionic polymer is an alcohol, an amine or alkyphenol alkoxylate.  
     
     
         12 . The electrolyte of  claim 11  wherein said composition is present in said electrolyte solution in a concentration of about 5% by weight.  
     
     
         13 . The electrolyte of  claim 9  wherein said organic acid is present in said composition in a wt. % of about 10, and wherein said non-ionic polymer is present in said composition in a wt. % of about 5.  
     
     
         14 . The electrolyte of  claim 13  wherein said organic acid is citric acid or acetic acid.  
     
     
         15 . The electrolyte of  claim 13  wherein said non-ionic polymer is an alcohol, an amine or alkyphenol alkoxylate.  
     
     
         16 . The electrolyte of  claim 15  wherein said organic acid is citric acid or acetic acid.  
     
     
         17 . A method for electroplating a metal onto a surface in an electroplating electrolyte solution, comprising the steps of: 
 providing a composition mixture comprising an organic acid and a non-ionic polymer;    forming a suspension layer of said composition mixture in said solution;    forming a wetting layer on said surface by passing said surface through said suspension layer and into said solution; and    electroplating said metal onto said surface.    
     
     
         18 . The method of  claim 17  wherein said organic acid is citric acid or acetic acid and said non-ionic polymer is an alcohol, an amine or alkyphenol alkoxylate.  
     
     
         19 . The method of  claim 17  wherein said organic acid is present in said composition in a wt. % of about 10, and wherein said ionic polymer is present in said composition in a wt. % of about 5.  
     
     
         20 . The method of  claim 17  further comprising a substrate and wherein said surface comprises a metal seed layer deposited on said substrate.