Patent ID: 8435379

Claim:
A ceiling electrode for a cleaning chamber which comprises a substrate support having a substrate receiving surface and a support electrode, the ceiling electrode comprising: a grounding ring; and a contoured ceiling electrode consisting of metal, the contoured ceiling electrode comprising: (a) an arcuate surface facing the substrate support, the arcuate surface having a diameter sized to extend across the substrate receiving surface of the substrate support and a cross-sectional thickness that changes across the substrate support to vary a dimension of a gap formed between the arcuate surface and the support electrode of the substrate support, thereby allowing a plasma density of a plasma formed between the arcuate surface and the substrate support to vary radially across the substrate support; (b) an annular band extending downwardly from a periphery of the arcuate surface through the grounding ring to encircle the substrate support; (c) a peripheral edge extending radially outwardly from the annular band, wherein said peripheral edge rests on the grounding ring; and wherein the annular band is spaced apart from a sidewall of the cleaning chamber by the grounding ring.