Reverse pulse plating composition and method

Abstract

A composition and method for electroplating a metal on a substrate. The composition has a chloride to brightener concentration ratio of from 20:1 to 125:1. The method of electroplating, which employs the composition, employs pulse patterns that improve physical properties of metal surfaces.

1 . A composition comprising chloride ion and a brightener having a concentration ratio of chloride ion to brightener of from 20:1 to 125:1 at a brightener concentration of from 0.001 ppm to 1.0 ppm.  
     
     
         2 . The composition of  claim 1 , wherein the chloride ion to brightener concentration ratio is from 25:1 to 120:1.  
     
     
         3 . The composition of  claim 1 , wherein a source of chloride ion is sodium chloride, potassium chloride, hydrogen chloride, or mixtures thereof.  
     
     
         4 . The composition of  claim 1  wherein the brightener comprises a compound having a formula HS—R—SO 3 X, XO 3 —S—R—S—S—R—SO 3 X or XO 3 —S—Ar—S—S—Ar—SO 3 X where R is a substituted or unsubstituted alkyl group, Ar is an aryl group, and X is a counter ion.  
     
     
         5 . The composition of  claim 1 , further comprising metal ions, levelers, suppressors, buffers, surfactants, or mixtures thereof.  
     
     
         6 . The composition of  claim 5 , wherein the metal ions comprise copper ions, nickel ions, tin ions, lead ions, chromium ions, palladium ions, gold ions, silver ions, platinum ions, indium ions, cadmium ions, bismuth ions, cobalt ions, rhodium ions, ruthenium ions, or zinc ions.  
     
     
         7 . The composition of  claim 5 , wherein the levelers comprise lactam alkoxylates having a formula:  
       
         
           
           
               
               
           
         
       
       where A is a hydrocarbon radical, R 1  is hydrogen or methyl, n is an integer of from 2 to 10, and n′ is an integer from 1 to 50.  
     
     
         8 . The composition of  claim 5 , wherein the levelers comprise a polyalkylene glycol ether of formula [R 2 —O(CH 2 CH 2 O) m (CH(CH 3 )—CH 2 O p —R 3 ] a  where m is an integer of from 8 to 800, p is an integer of from 0 to 50, R 2  is a (C 1 -C 4 )alkyl, R 3  is an aliphatic chain or an aromatic group, and a is 1 or2.  
     
     
         9 . The composition of  claim 5 , wherein the levelers comprise compounds having a formula N—R 4 —S where R 4  is a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group.  
     
     
         10 . The composition of  claim 5 , wherein the suppressors comprise polyhydroxy compounds.  
     
     
         11 . A method comprising: 
 (a) generating an electromotive force through a cathode, anode and a composition in electrical communication to provide an electric field around the cathode, the anode and the composition, the composition comprises metal ions, brighteners and chloride ions, the chloride ions to brighteners concentration ratio is from 20:1 to 125:1;    (b) modifying the electric field around the cathode, the anode and the composition to provide a pulse pattern or a combination of pulse patterns comprising (i) cathodic current followed by anodic current; (ii) cathodic current followed by anodic current followed by cathodic DC current; (iii) cathodic current followed by anodic current followed by equilibration; or (iv) cathodic current followed by anodic current followed by cathodic DC current then followed by equilibration to electroplate a metal on the cathode.    
     
     
         12 . The method of  claim 11 , wherein the cathodic current is from 40 ms to 1 second and the anodic current is from 0.25 ms to 15 ms for pulse pattern (i).  
     
     
         13 . The method of  claim 11 , wherein the cathodic current is from 40 ms to 1 second and the anodic current is from 0.25 ms to 15 ms and the cathodic DC current is from 5 seconds to 90 seconds of pulse pattern (ii).  
     
     
         14 . The method of  claim 11 , wherein the cathodic current is from 40 ms to 1 second and the anodic current is from 0.25 ms to 15 ms and equilibration is from 5 seconds to 90 seconds.  
     
     
         15 . The method of  claim 11 , wherein the cathodic current is from 40 ms to 1 second and the anodic current is from 0.25 ms to 15 ms and the cathodic DC current is from 5 seconds to 90 seconds and equilibration is from 5 seconds to 90 seconds.  
     
     
         16 . The method of  claim 11 , wherein a current density is from 5 mA/cm 2  to 200 mA/cm  
     
     
         17 . The method of  claim 11 , wherein the metal that is plated comprises copper, tin, nickel, cobalt, chromium, cadmium, lead, silver, gold, platinum, palladium, bismuth, indium, rhodium, ruthenium, iridium, zinc or alloys thereof.  
     
     
         18 . The method of  claim 11 , wherein the composition further comprises levelers, suppressors, surfactants, buffers or mixtures thereof.  
     
     
         19 . The method of  claim 11 , wherein the cathode is a printed circuit board or a silicon wafer.  
     
     
         20 . The method of  claim 11 , wherein the composition comprises brighteners in an amount of from 0.001 ppm to 1.0 ppm.