Patent ID: 8382942

Claim:
A focus ring assembly configured to reduce process effects on the backside of a substrate that is cantilevered beyond an edge of a substrate holder support surface on which the substrate rests, the focus ring assembly comprising: a focus ring positioned on a step receiving surface of the substrate holder which is axially recessed from the substrate holder support surface and extends radially outward from the edge of the substrate holder support surface, the focus ring comprising: a bottom surface which contacts the step receiving surface of the substrate holder, a top surface which opposes the bottom surface and is axially positioned at a higher level than the substrate support surface when the focus ring is positioned on the step planar level as a top surface of the substrate, and a lip having a lip receiving surface axially located between the bottom surface and top surface of the focus ring, such that the lip receiving surface is located directly below and in opposition to a backside surface of a substrate resting on the substrate support surface of the substrate holder, and an outer radial lip surface positioned radially outward from a peripheral edge of the substrate and extending substantially perpendicularly upward from the lip receiving surface to the top surface of the focus ring such that the peripheral edge of said substrate is substantially parallel to the outer radial lip surface and a clearance space is formed between a cantilevered portion of the substrate and the lip of the focus ring; and a secondary focus ring including a bottom most surface positioned on and in contact with the lip receiving surface of the focus ring, the secondary focus ring including an outer radial edge surface extending axially upward from the bottommost surface in contact with the lip receiving surface and positioned radially outward from the peripheral edge of the substrate, wherein said focus ring is configured to couple to a substrate holder configured to support a substrate exposed to a process in a processing system, and said secondary focus ring is configured to reduce deposition of material from said process on a backside surface of said substrate.