A method for substantially simultaneously polishing a copper conductive structure of a semiconductor device structure and an adjacent barrier layer. The method includes use of a polishing pad with a slurry solution in which copper and a material, such as tungsten, of the barrier layer are removed at substantially the same rate. The slurry is formulated so as to oxidize copper and a material of the barrier layer at substantially the same rates. Thus, copper and the barrier layer material have substantially the same oxidation energies in the slurry. Systems for substantially polishing copper conductive structures and adjacent barrier structures on semiconductor device structures are also disclosed.