A copper/barrier CMP process includes (a) providing a substrate having a bulk metal layer and a barrier layer; (b) polishing the substrate with a first hard polishing pad on a first platen to substantially remove an upper portion of the bulk metal layer, wherein the first hard polishing pad has a hardness of above 50 (Shore D); (c) polishing the substrate with a second hard polishing pad on a second platen to remove residual copper, thereby exposing the barrier layer, wherein the second hard polishing pad has a hardness of above 50 (Shore D); and (d) polishing the substrate with a third hard polishing pad on a third platen to remove the barrier layer, wherein the third hard polishing pad has a hardness ranging between 40-50 (Shore D).