Patent ID: 7033257

Claim:
A carrier head for supporting a wafer during a chemical mechanical polishing process, said carrier head comprising: a wear ring including a surface to be in frictional engagement with a polishing pad, wherein said wear ring includes a shoulder provided in a recess in said wear ring; and a slidably movable pressure plate disposed within said wear ring, said pressure plate adapted to provide slidable movement relative to said wear ring to account for height dimensional changes that may occur in said wear ring as a result of the frictional engagement with the polishing pad, wherein said pressure plate includes a stop configured to engage the shoulder in the wear ring to limit travel of said pressure plate relative to said wear ring, wherein said pressure plate further includes a circumferentially disposed sealing member to provide an airtight seal relative to a pressurizing chamber, and wherein said pressure plate is responsive to pressurized air in said pressurizing chamber to be coplanar with the wear ring surface and apply a uniform compression force to the wafer notwithstanding of height dimensional changes that can occur in the wear ring.