Patent ID: 6159073
Filing Date: 2000-12-12
Classification: B24B,B24D,G01B

Abstract:
A method of measuring a characteristic of a layer on a substrate during chemical mechanical polishing, comprising:bringing a surface of the substrate into contact with a polishing pad that has a window;causing relative motion between the substrate and the polishing pad;directing a light beam through the window, the motion of the polishing pad relative to the substrate causing the light beam to move in a path across the substrate surface;monitoring an interference signal produced by the light beam reflecting off the substrate;extracting a plurality of intensity measurements from the interference signal, each intensity measurement corresponding to a sampling zone in the path across the substrate surface;determining a radial position for each sampling zone;dividing the intensity measurements into a plurality of radial ranges according to the radial positions; andcomputing the characteristic for each radial range from the intensity measurements associated with that radial range.