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 - 10 . (canceled)  
   
   
       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 2 .  
   
   
       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.