Patent ID: 8097082

Claim:
An electrode assembly for processing a substrate, comprising: a conductive faceplate having a nonplanar surface configured to face the substrate during processing, wherein the conductive faceplate is disposed so that the nonplanar surface is opposing a substrate support having an electrode, the conductive faceplate and the substrate support form a plasma volume, a RF power source is applied between the conductive faceplate and the electrode, and the nonplanar surface is configured to reduce density of the electric field near an edge region of the substrate, the non planar surface of the conductive faceplate comprises: an inner planar portion corresponding to a center portion of the substrate; a recess outward to the planar portion and corresponding to the edge region of the substrate; and an outer planar portion outward to the recess, wherein the recess is smoothly connected to the inner planar portion and outer planar portion without corners, the recess is formed from an inner slope and an outer slope, the inner slope is outwardly initiated from the inner planar portion, the outer slope is inwardly initiated from the outer planar portion, the inner and outer slopes meet at a bottom of the recess, the recess having a maximum depth of about 0.5 mm to about 2 mm at a radius of about 130 mm to about 140 mm from a center of the conductive faceplate, the inner slope is initiated at a radius of about 80 mm to about 100 mm, and the outer slope is initiated at a radius of about 140 mm to about 145 mm.