Patent ID: 7654888

Claim:
A carrier head for chemical mechanical polishing of a substrate having a front surface, a back surface and an edge, comprising: a housing having an upper end configured for connection to a drive shaft; a base assembly connected to and vertically movable relative to the housing; an annular retaining ring connected to and positioned beneath the base assembly, the annular retaining ring having a lower surface configured to contact a polishing pad and an inner surface configured to circumferentially surround the edge of a substrate to retain the substrate, the retaining ring vertically movable relative to the base assembly; a carrier ring connected to and positioned beneath the base assembly, the carrier ring circumferentially surrounding the retaining ring to prevent lateral motion of the retaining ring, the carrier ring having a bottom surface configured to contact a polishing pad, the carrier ring vertically fixed relative to the base assembly; and a flexible membrane connected to and extending beneath the base assembly to define a pressurizable chamber therebetween, the flexible membrane having a lower surface to provide a substrate-mounting surface, wherein the annular retaining ring is configured to be pressured independently of the chamber.