US Patent 9878421 Chemical mechanical polishing retaining ring with integrated sensor

A retaining ring for a chemical mechanical polishing carrier head having a mounting surface for a substrate is provided herein. In some embodiments, the retaining ring may include an annular body have a central opening, a channel formed in the body, wherein a first end of the channel is proximate the central opening, and a sensor disposed within the channel and proximate the first end, wherein the sensor is configured to detect acoustic and/or vibration emissions from processes performed on the substrate.