A substrate processing apparatus for processing substrates comprises a processing chamber in which a substrate is processed. A process gas source is adapted to supply process gas into the processing chamber. A RF energy source is adapted to energize the process gas into a plasma state in the processing chamber. A vacuum source is adapted to exhaust byproducts of the processing from the processing chamber. The processing chamber includes an electrostatic chuck assembly having a layer of ceramic material that includes an upper electrostatic clamping electrode and at least one RF electrode, a temperature controlled RF powered baseplate, and at least one annular electrically conductive gasket extending along an outer portion of an upper surface of the temperature controlled RF powered baseplate. The at least one annular electrically conductive gasket electrically couples the upper surface of the temperature controlled RF powered baseplate to the at least one RF electrode.