Patent ID: 9067295
Filing Date: 2015-06-30
Classification: B24B

Abstract:
1. A chemical mechanical polishing apparatus, comprising: a carrier head including a retaining ring having a plastic portion with a bottom surface to contact a polishing pad; a platen to support the polishing pad; an in-situ monitoring system including a sensor that generates a signal during a polishing operation while the bottom surface of the plastic portion contacts the polishing pad, wherein the signal depends on a thickness of the plastic portion, and wherein the sensor is supported by the platen at a position below the polishing surface positioned on a side of the polishing pad farther from the retaining ring; and a controller configured to receive the signal from the in-situ monitoring system and to adjust at least one polishing parameter in response to the signal to compensate for nonuniformity caused by changes in the thickness of the plastic portion of the retaining ring.