Patent ID: 6399501
Filing Date: 2002-06-04
Classification: B24B,H01L

Abstract:
An endpoint detection method for chemical mechanical polishing, comprising:a) bringing a surface of a substrate into contact with a polishing pad; b) causing relative motion between the substrate and the polishing pad; c) directing a light beam to contact the surface of the substrate; d) moving the light beam in a path across the substrate surface that passes through a plurality of zones; e) monitoring an intensity signal produced by the light beam reflecting off the substrate; f) for each zone in the plurality of zones, extracting a plurality of intensity measurements from the intensity signal as the light beam moves across the substrate; g) for each zone in the plurality of zones, selecting a first local extreme intensity measurement from the plurality of intensity measurements in that zone; h) iterating steps c)-g) for a plurality of sweeps of the light beam across the substrate and storing the first local extreme intensity measurement from each zone and each sweep to generate a first plurality of extreme intensity measurements; and i) detecting a polishing endpoint based on the first plurality of extreme intensity measurements.