Patent ID: 6945845

Claim:
A polishing system, comprising: a polishing pad support to hold a polishing pad having a polishing surface; a carrier to hold a substrate against the polishing surface of the polishing pad; and an eddy current monitoring system including an induction coil, the eddy current monitoring system positioned to generate a magnetic field through the pad into a sensing region of the system current polishing, wherein each component of the carrier with at least a portion positioned during polishing within a sensing distance of the polishing surface in the sensing region is nonconductive, and wherein, in response to generating the magnetic field, the eddy current monitoring system is to receive an eddy current signal from one or more conductive regions on the substrate, and a noise signal during polishing, and wherein the sensing distance is a distance beyond which an eddy current signal from one or more conductive components of the carrier is not discernible over the noise signal.