Carrier head with a flexible membrane and an edge load ring

摘要

A carrier head for chemical mechanical polishing includes a base (104) and a flexible membrane (118). A lower surface (122) of the flexible membrane provides a substrate receiving surface of a substrate (10). The lower surface includes a first surface (210) to apply a first pressure to a first portion of the substrate. A second surface (222b) surrounding the first surface applies a second pressure on a second portion of the substrate. An edge load ring (120) surrounds the second surface. A lower surface (234) of the edge load ring provides a third surface to apply a third pressure to a third portion of the substrate surrounding the second portion.