Patent ID: 7491118
Filing Date: 2009-02-17
Classification: B24B

Abstract:
1. A chemical mechanical polishing apparatus comprising: a platen; a polishing pad affixed to a surface of the platen; and a polishing head configured to retain and rotate a wafer while pressing a surface of the rotating wafer against the polishing pad, wherein the platen and the polishing head interoperate such that the rotating wafer moves in a loop across a surface of the pad, wherein the polishing head comprises a retaining ring that retains an edge of the wafer and that extends flush with the surface of the wafer and wherein a first portion of the polishing pad that engages the retaining ring of the polishing head proximate an innermost portion of the loop provides less rigidity than a second portion of the polishing pad that engages an entire surface of the wafer, wherein the polishing pad and the platen interoperate to provide a cushion where the polishing pad engages the retaining ring of the polishing head, wherein the cushion comprises an airspace bounded by the pad and/or the platen, wherein the airspace comprises a recess in the pad and/or a recess in the platen, wherein the pad comprises: wherein the second resilient layer has an opening therethrough between the recess of the first resilient layer and the surface of the platen.