System and method for pulse current plating

Abstract

According to one embodiment of the present invention, a method for electroplating electronic devices is disclosed which includes placing the outer surface of a substrate in contact with a solution comprising a conductive material. An electrical current is passed through the solution and the substrate so as to cause the conductive material to deposit on the substrate under the electromotive force caused by the electrical current. The level of the electrical current is varied from a first current level to a second current level to provide for differing rates of deposition of the conductive material on the substrate. The second current level provides a relaxation period to allow the conductive material deposited on the substrate to come to equilibrium.

What is claimed is:  
     
         1 . A method for electroplating electronic devices, comprising: 
 placing an outer surface of a substrate in contact with a solution comprising a conductive material, passing electrical current through the solution and the substrate so as to cause the conductive material to deposit on the substrate under the electromotive force caused by the electrical current;    varying the level of the electrical current from a first current level to a second current level to provide for differing rates of deposition of the conductive material on the substrate;    wherein the second current level provides a relaxation period to allow the conductive material deposited on the substrate to come to an equilibrium.    
     
     
         2 . The method of  claim 1 , wherein the second current level is no current applied for time interval comprising 0.001 to 5.0 seconds.  
     
     
         3 . The method of  claim 1 , wherein the first current is a cathodic current.  
     
     
         4 . The method of  claim 1 , wherein the first current is a cathodic current applied for a time interval comprising 0.001 to 5.0 seconds.  
     
     
         5 . The method of  claim 1 , and further comprising varying the level of the electrical current from the second current level to a third current level.  
     
     
         6 . The method of  claim 5 , wherein the second current level is no current, the third current level comprising a cathodic current applied.  
     
     
         7 . The method of  claim 5 , wherein the second current level is no current, the third current level comprising a cathodic current applied for a time interval comprising 0.001 to 5.0 seconds.  
     
     
         8 . The method of  claim 5 , wherein the second current level is no current, the third current level comprising an anodic current level.  
     
     
         9 . The method of  claim 1 , wherein the conductive material comprises a bump on the outer surface of the substrate.  
     
     
         10 . The method of  claim 1 , wherein the conductive material comprises a stud on the outer surface of the substrate.  
     
     
         11 . A system for electroplating electronic devices comprising: 
 a container operable to hold a solution comprising a conductive material;    a chuck operable to hold the workpiece in contact with the solution;    a rotator coupled to the chuck and operable to rotate the chuck and the workpiece in the solution;    a rotation controller coupled to the rotator and operable to control the rate of rotation of the workpiece in the solution;    a current source coupled to the solution and to the workpiece and operable to supply an electric current traveling through the solution and the workpiece;    a current flow controller coupled to the power supply and operable to control the amount of electric current flowing through the solution and the workpiece at any given time, the controller operable to change the amount of current flowing through the solution and the workpiece from a first current level to a second current level to provide for differing rates of deposition of the conductive material on the substrate, the second current level providing a relaxation period to allow the conductive material deposited on the substrate to come to an equilibrium.    
     
     
         12 . The system of  claim 11 , wherein the second current level is no current applied for time interval comprising 0.001 to 5.0 seconds.  
     
     
         13 . The system of  claim 11 , wherein the first current is a cathodic current.  
     
     
         14 . The system of  claim 11 , wherein the first current is a cathodic current applied for a time interval comprising 0.001 to 5.0 seconds.  
     
     
         15 . The system of  claim 11 , wherein the current flow controller is further operable to vary the level of the electrical current from the second current level to a third current level.  
     
     
         16 . The system of  claim 15 , wherein the second current level is no current, the third current level comprising a cathodic current.  
     
     
         17 . The system of  claim 15 , wherein the second current level is no current, the third current level comprising a cathodic current applied for a time interval comprising 0.1 to 50 seconds.  
     
     
         18 . The system of  claim 11 , wherein the second current level is no current, the third current level comprising an anodic current level.  
     
     
         19 . The system of  claim 11 , wherein the conductive material comprises a bump on the outer surface of the substrate.  
     
     
         20 . The system of  claim 11 , wherein the conductive material comprises a stud on the outer surface of the substrate.