Plating uniformity control by contact ring shaping

An apparatus for providing an electrical bias to a substrate in a processing system is described. The apparatus generally includes a conductive annular body defining a central opening. The conductive annular body may have a substrate seating surface adapted to receive the substrate and a plurality of scallops formed on a surface opposing the substrate seating surface. A plurality of electrical contacts may be formed on the substrate seating surface opposite the plurality of scallops. The electrical contacts may be adapted to engage a plating surface of the substrate.