Methods for electrochemical deposition of multi-component solder using cation permeable barrier

Abstract

Processes and systems for electrochemical deposition of a multi-component solder by processing a microfeature workpiece with a first processing fluid and an anode are described. Microfeature workpieces are electrolytically processed using a first processing fluid, an anode, a second processing fluid, and a cation permeable barrier layer. The cation permeable barrier layer separates the first processing fluid from the second processing fluid while allowing certain cationic species to transfer between the two fluids.

1 . A process for electrolytically processing a microfeature workpiece as the working electrode in a first processing fluid and a counter electrode in a second processing fluid, the method comprising:
 (a) contacting a surface of the microfeature workpiece with the first processing fluid, the first processing fluid including at least a first metal cation;   (b) contacting the counter electrode with a second processing fluid, the second processing fluid including a second metal cation;   (c) allowing the second metal cation to move from the second processing fluid to the first processing fluid, but substantially preventing movement of the first metal cation from the first processing fluid to the second processing fluid by providing a cation permeable barrier between the first processing fluid and the second processing fluid, wherein the primary mass transport of the second metal cation from the second processing fluid to the first processing fluid is across the cation permeable barrier; and   (d) electrolytically depositing the first and second metal cations onto the surface of the microfeature workpiece.   
     
     
         2 . The process of  claim 1 , wherein the cation permeable barrier is a cation exchange membrane. 
     
     
         3 . The process of  claim 1 , further comprising producing an electrochemical reaction at the counter electrode to produce the second metal cation. 
     
     
         4 . The process of  claim 1 , wherein the working electrode is a cathode, and the counter electrode is an anode. 
     
     
         5 . The process of  claim 1 , wherein the first processing fluid is dosed with the first metal cation. 
     
     
         6 . The process of  claim 1 , wherein the counter electrode is a consumable electrode. 
     
     
         7 . The process of  claim 1 , wherein either or both of the first and second processing fluids is dosed with the second metal cation. 
     
     
         8 . The process of  claim 7 , wherein dosing in either or both of the first and second processing fluids with the second metal cation is not the major source of the second metal cation in the first processing fluid. 
     
     
         9 . The process of  claim 1 , wherein the first metal cation concentration in the first processing fluid is in the range of about 0.1 g/L to about 5.0 g/L. 
     
     
         10 . The process of  claim 1 , wherein the second metal cation concentration in the first processing fluid is selected from the group consisting of in the range of about 40 to about 80 g/L, about 40 to about 120 g/L, and about 40 to about 150 g/L. 
     
     
         11 . The process of  claim 1 , wherein the pH of the second processing fluid is higher than the pH of the first processing fluid. 
     
     
         12 . The process of  claim 1 , wherein the pH of the second processing fluid is selected from the group consisting of about 1.0 to about 2.0, about 1.2 to about 1.8, about 1.5 to about 2.2, greater than about 2.0, about 1.0 to about 3.0, and about 2.0 to about 3.0. 
     
     
         13 . The process of  claim 12 , wherein the pH of the first processing fluid is selected from the group consisting of less than or equal to 1.0, less than or equal to 0.5, and in the range of 0 to 1.0. 
     
     
         14 . The process of  claim 1 , wherein the first metal cation is selected from the group consisting of copper ion, lead ion, gold ion, tin ion, silver ion, bismuth ion, indium ion, platinum ion, ruthenium ion, rhodium ion, iridium ion, osmium ion, rhenium ion, palladium ion, and nickel ion. 
     
     
         15 . The process of  claim 1 , wherein the second metal cation is selected from the group consisting of copper ion, lead ion, tin ion, bismuth ion, indium ion, silver ion, platinum ion, ruthenium ion, rhodium ion, iridium ion, osmium ion, rhenium ion, palladium ion, and nickel ion. 
     
     
         16 . The process of  claim 1 , further comprising a third metal cation selected from the group consisting of copper ion, lead ion, gold ion, tin ion, silver ion, bismuth ion, indium ion, platinum ion, ruthenium ion, rhodium ion, iridium ion, osmium ion, rhenium ion, palladium ion, nickel ion. 
     
     
         17 . (canceled) 
     
     
         18 . The process of  claim 1 , wherein at least one of the first processing fluid and the second processing fluid includes an antioxidant. 
     
     
         19 . (canceled) 
     
     
         20 . The process of  claim 1 , where the second processing fluid is not dosed into the first processing fluid. 
     
     
         21 . A process for electrolytically processing a microfeature workpiece as the working electrode with a first processing fluid and a counter electrode, comprising:
 (a) contacting a surface of the microfeature workpiece with the first processing fluid, the first processing fluid comprising first processing fluid species including at least a first metal cation;   (b) contacting the counter electrode with a second processing fluid;   (c) producing an electrochemical reaction at the counter electrode to produce a second metal cation in the second processing fluid;   (d) providing a cation exchange membrane to allow the second metal cation to move from the second processing fluid to the first processing fluid, but to substantially prevent movement of the first metal cation from the first processing fluid to the second processing fluid when electrolytically processing the microfeature workpiece; and   (e) separating the second processing fluid from the membrane when not electrolytically processing the microfeature workpiece.   
     
     
         22 . A process for electrolytically processing a microfeature workpiece as the cathode with a first processing fluid and an anode, comprising:
 (a) contacting a surface of the microfeature workpiece with the first processing fluid, the first processing fluid comprising first processing fluid species including at least a first metal cation;   (b) contacting the anode with a second processing fluid;   (c) consuming the anode to produce a second metal cation in the second processing fluid;   (d) providing a cation exchange membrane to allow the second metal cation to move from the second processing fluid to the first processing fluid, but to substantially prevent movement of the first metal cation from the first processing fluid to the second processing fluid, wherein the second processing fluid is not dosed in the first processing fluid; and   (e) electrolytically depositing the first and second metal cations onto the surface of the microfeature workpiece.