Apparatus for processing a substrate is disclosed herein. In some embodiments, a substrate support may include a substrate support having a support surface for supporting a substrate the substrate support having a central axis; a first electrode disposed within the substrate support to provide RF power to a substrate when disposed on the support surface; an inner conductor coupled to the first electrode about a center of a surface of the first electrode opposing the support surface, wherein the inner conductor is tubular and extends from the first electrode parallel to and about the central axis in a direction away from the support surface of the substrate support; an outer conductor disposed about the inner conductor; and an outer dielectric layer disposed between the inner and outer conductors, the outer dielectric layer electrically isolating the outer conductor from the inner conductor. The outer conductor may be coupled to electrical ground.