US Patent 11904429 Substrate polishing apparatus with contact extension or adjustable stop

An apparatus for chemical mechanical polishing (CMP) of a substrate is described herein. The apparatus includes an extension disposed between a retaining ring and a chucking membrane. The extension is disposed radially outward from the edge of the substrate and is configured to contact the retaining ring during substrate processing. The extension provides a repeatable and controlled point of contact between the retaining ring and the chucking membrane. The extension may have multiple configurations, such that the contact point between the retaining ring and the chucking membrane is set at a pre-determined location or such that the contact point is moveable by an adjustable stop.