Patent ID: 6494766
Filing Date: 2002-12-17
Classification: B24B,B24D,G01B

Abstract:
A method of chemical mechanical polishing, comprising:bringing a surface of the substrate into contact with a polishing surface causing relative motion between the substrate and the polishing surface; directing a light beam through the polishing surface to impinge the substrate; causing the light beam to move in a path across the substrate surface; monitoring an interference signal produced by reflections of the light beam off the substrate; extracting a sequence of intensity measurements from the interference signal, each intensity measurement corresponding to a different sampling zone in the path of the same light beam across the substrate surface; associating each of the intensity measurements with a radial position on the substrate; dividing the intensity measurements into a plurality of radial ranges according to the radial positions; and determining a polishing endpoint from the intensity measurements in at least one radial range.