Electrolytic copper process using anion permeable barrier

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 and a second metal cation, the microfeature workpiece having a nonmetallic substrate having a dielectric layer disposed over the substrate and a continuous metal feature disposed on the dielectric layer and having microfeatures comprising recessed structure;
• (b) contacting the counter electrode with the second processing fluid;
• (c) providing an anion permeable barrier between the first processing fluid and the second processing fluid to substantially prevent movement of cationic species between the first processing fluid and the second processing fluid;
• and
• (d) electrolytically depositing the first and second metal cations onto the surface of the microfeature workpiece.