Patent ID: 8740206

Claim:
A ring assembly, comprising: an outer ring body having a top surface, a bottom surface substantially parallel to the top surface, and an inside surface that extends between the top surface and the bottom surface, the inside surface having a notch, and the notch having a roof projecting from an upper portion of the outer ring body, wherein the outer ring body further comprises: an outside surface extending between the top and bottom surfaces; a first annular extension extending from the bottom surface in a direction away from the top surface and from a location spaced from an edge of the outside surface; a second annular extension extending from the bottom surface in a direction away from the top surface, the second annular extension abutting the inside surface; and a third annular extension extending from the outer ring body in a direction away from the outside surface, the third annular extension forming part of the inside surface and having a surface slanted relative to the top surface and the bottom surface of the outer ring body at an angle of between about 100 degrees and about 120 degrees; and an inner ring body nestable in the notch of the outer ring body when either a top surface or a bottom surface of the inner ring body is disposed adjacent the roof, the ring assembly with either top surface or the bottom surface of the inner ring body nested in the notch of the outer ring body is configured to interface with a substrate support of a plasma processing chamber, wherein before the top surface is eroded, the inner ring body can be flipped over along an axis that is parallel to the top surface of the outer ring body so that a top surface of a profile of the ring assembly does not change regardless of the bottom surface or top surface of the inner ring body being disposed against the outer ring body.