Patent ID: 7566391

Claim:
A method for removing material from a microfeature workpiece, comprising: providing a microfeature workpiece having a substrate material, a recess in a surface of the substrate material, a first layer disposed adjacent to the surface of the substrate material and in the recess, and a second layer disposed adjacent to the first layer, the first layer including at least one of tantalum and tantalum nitride; disposing a first polishing liquid in contact with the second layer, the first polishing liquid containing a generally aqueous electrolytic medium; removing a first portion of the second layer external to the recess from the microfeature workpiece with the first polishing liquid; replacing the first polishing liquid with a second polishing liquid different than the first polishing liquid, the second polishing liquid including a generally organic electrolytic medium in contact with the first layer, the electrolytic medium containing an organic salt; positioning first and second electrodes in electrical communication with the first layer, the second layer, and the second polishing medium, at least one of the first and second electrodes being spaced apart from the microfeature workpiece; removing at least a portion of the first layer external to the recess at a first rate by passing an electrical current along an electrical path that includes the first electrode, the electrolytic medium, the first layer, and the second electrode; removing a second portion of the second layer at a second rate by passing an electrical current along an electrical path that includes the first electrode, the electrolytic medium, the second layer, and the second electrode while removing the at least a portion of the first layer; and wherein the organic salt is selected such that the first rate is faster than the second rate.