Patent ID: 8337278

Claim:
A system, comprising: a polishing apparatus having one or more polishing stations for polishing of a substrate, the polishing stations operating with a plurality of polishing parameters; an in-line monitoring system including a substrate holder to hold the substrate at a location outside the polishing stations, a housing having an opening for receiving the substrate, and an eddy current sensor outside the polishing stations and near the opening to generate a signal based on a thickness of a layer of the substrate, wherein the sensor and the substrate holder are configured to undergo relative motion; and a controller configured to cause the substrate holder to insert the substrate into the opening in the housing and to cause the sensor and substrate to undergo relative motion such that the sensor traverses a path including three or more angularly separated positions adjacent an edge of the substrate, the sensor configured to generate measurements at the three or more angularly separated positions, and the controller configured to receive the signal from the sensor and control at least one of the plurality of polishing parameters in response to the measurements.