Patent ID: 7198677

Claim:
A wafer processing system comprising: a process chamber; a wafer support for supporting a wafer during processing; a gas inlet for introducing process gases into the chamber; an electrically conductive ring surrounding the wafer support and in approximately the same plane as the wafer, wherein the ring separates the chamber into an upper portion and a lower portion, the ring comprising a recessed inner ledge on the same plane as the wafer and extending under the wafer to support the wafer and an outer ring portion thicker than the inner ledge, wherein the ring has a plurality of holes located in the outer ring portion and outside the inner ledge and the outer circumference of the wafer to allow a balancing of pressure between the upper and lower portions; and a non-electrically conductive inner ring between the inner ledge and the wafer to support the wafer; wherein the shape of the inner ring substantially corresponds to the shape of the recessed inner ledge.