Embodiments of the invention generally provide a method and apparatus for processing a substrate in an electrochemical mechanical planarizing system. In one embodiment, a cell for polishing a substrate includes a processing pad disposed on a top surface of a platen assembly. A plurality of conductive elements are arranged in a spaced-apart relation across the upper planarizing surface and adapted to bias the substrate relative to an electrode disposed between the pad and the platen assembly. A plurality of passages are formed through the platen assembly between the top surface and a plenum defined within the platen assembly. In another embodiment, a system is provided having a bulk processing cell and a residual processing cell. The residual processing cell includes a biased conductive planarizing surface. In further embodiments, the conductive element is protected from attack by process chemistries.