Patent ID: 8128791

Claim:
A plating cell for plating copper onto partially fabricated integrated circuit wafers, the plating cell comprising: a catholyte portion adapted for receiving wafers in a catholyte; a separate anode chamber configured for holding an anode and maintaining an anolyte in ionic communication with the catholyte; a recirculation system of the anolyte; a make up solution entry port configured for directly dosing the recirculating anolyte with make up solution; a diluent entry port configured for dosing recirculating anolyte or the make up solution with a diluent; a controller comprising program instructions for separately controlling delivery of the diluent and the make up solution to the recirculating anolyte, wherein the program instructions specify dosing parameters for the diluent and the make up solution such as to minimize precipitation-induced passivation of the anode; and a cation exchange membrane on the separate anode chamber, wherein the cation exchange membrane provides a path for the ionic communication between the anolyte and the catholyte.