Patent ID: 6764380
Filing Date: 2004-07-20
Classification: B24B,B24D,G01B

Abstract:
A chemical mechanical polishing apparatus, comprising:a platen supporting a polishing surface; a carrier head for holding a substrate having a layer thereon in contact with the polishing surface; a motor to move at least one of the platen and the carrier head to cause relative motion between the polishing surface and the substrate; a substrate monitoring system including a sensor secured to the platen to generate a signal that depends on a thickness of the layer, the motion of the platen relative to the substrate causing the sensor to move in a path across the substrate surface; a computer configured to receive the signal and extract a sequence of measurements from the signal, each measurement corresponding to a sampling zone in the path across the substrate surface, determine a radial position for each sampling zone, divide the measurements into a plurality of radial ranges according to the radial positions, and determine a characteristic of the substrate layer for each radial range from the measurements associated with that radial range.