Electrolytic process using cation permeable barrier

Abstract

Processes and systems for electrolytically 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. The described processes produce deposits over repeated plating cycles that exhibit deposit properties (e.g., resistivity) within desired ranges.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
         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 the 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; 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 first processing fluid is a catholyte. 
     
     
         3 . The process of  claim 1 , wherein the second processing fluid is an anolyte. 
     
     
         4 . The process of  claim 1 , wherein 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 includes providing a cation permeable barrier between the first processing fluid and the second processing fluid. 
     
     
         5 . The process of  claim 4 , wherein the cation permeable barrier is a cation exchange membrane. 
     
     
         6 . The process of  claim 1 , further comprising producing an electrochemical reaction at the counter electrode to produce the second metal cation. 
     
     
         7 . The process of  claim 1 , wherein the working electrode is a cathode, and the counter electrode is an anode. 
     
     
         8 . The process of  claim 1 , wherein the counter electrode is a consumable electrode. 
     
     
         9 . The process of  claim 1 , wherein the first processing fluid is dosed with the first metal cation. 
     
     
         10 . The process of  claim 1 , wherein the pH of the second processing fluid is higher than the pH of the first processing fluid. 
     
     
         11 . The process of  claim 1 , wherein the first metal cation is selected from the group consisting of copper ion, silver ion, tin ion, iron ion, and antimony ion. 
     
     
         12 . The process of  claim 1 , wherein the second metal cation is selected from the group consisting of tin ion, lead ion, and nickel ion. 
     
     
         13 . The process of  claim 1 , further comprising a third metal cation in the first processing fluid selected from the group consisting of silver, copper, and antimony. 
     
     
         14 . The process of  claim 1 , wherein the second processing fluid includes an additive to prevent metal ions from oxidizing in the second processing fluid. 
     
     
         15 . The process of  claim 1 , wherein the second processing fluid further includes a stabilizing agent to stabilize metal ions in solution. 
     
     
         16 . 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 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, wherein the pH of the second processing fluid is higher than the pH of the first 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; and   (e) electrolytically depositing the first and second metal cations onto the surface of the microfeature workpiece.   
     
     
         17 . 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 a first metal cation;   (b) contacting the anode with a second processing fluid;   (c) consuming the anode to produce a second metal cation, wherein the pH of the second processing fluid is higher than the pH of the first 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; and   (e) electrolytically depositing the first and second metal cations onto the surface of the microfeature workpiece.