Patent ID: 8500953

Claim:
An edge ring assembly adapted to surround a substrate support surface in a plasma etching chamber comprising: an edge ring dimensioned so as to underlie a substrate located on a substrate support surface in the chamber and provide a clearance gap between a lower surface of the substrate and an upper surface of the edge ring, the gap allowing for thermal expansion during plasma etching and minimizing polymer deposition on the underside or bevel edge of the substrate; and a dielectric spacer ring between the edge ring and the substrate support surface dimensioned so as to provide a clearance gap between a lower surface of a substrate located on the substrate support surface and an upper surface of the dielectric spacer ring wherein the dielectric spacer ring comprises an axially upward extending portion formed on a radially inner surface of a coupling ring, and the coupling ring includes bolt holes therein which receive bolts attaching the coupling ring to a temperature controlled and radiofrequency powered baseplate beneath an electrostatic chuck comprising the substrate support, the gap allowing for thermal expansion during plasma etching and minimizing polymer deposition on the underside or bevel edge of the substrate; wherein the upper surface of the dielectric spacer ring and an innermost upper surface of the edge ring are substantially co-planar when the dielectric spacer ring and the edge ring are mounted in the chamber; a radially outer portion of the edge ring is thicker than the dielectric spacer ring; the edge ring includes an upper inner surface which is inclined and spaced outwardly from the substrate; the coupling ring and edge ring have the same outer diameter; and the dielectric spacer ring electrically insulates the edge ring from the baseplate.