Patent ID: 8721391
Filing Date: 2014-05-13
Classification: B24B

Abstract:
1. A carrier head for a chemical mechanical polisher, comprising: a base; a substrate mounting surface; an inner ring having an inner surface configured to circumferentially surround an edge of a substrate positioned on the substrate mounting surface, an outer surface, a lower surface to contact a polishing pad, an outwardly projecting lip at the outer surface, the lip including a horizontal lower surface, and a sloped area connecting a lower region of the outer surface to the horizontal lower surface of the lip, the inner ring vertically movable relative to the substrate mounting surface, the lower surface of the inner ring having a first width; and an outer ring having an inner surface circumferentially surrounding the inner ring, an outer surface, an annular upper surface, and a lower surface to contact the polishing pad, the outer ring vertically movable relative to and independently of the substrate mounting surface and the inner ring, wherein the lower surface of the outer ring has a second width greater than the first width, wherein the inner surface of the outer ring has a sloped portion having the same angle of inclination as the sloped area, and wherein the horizontal lower surface of the lip is configured to provide a hard stop for the annular upper surface of the outer ring.