Patent ID: 7780503

Claim:
An apparatus for polishing a workpiece having a surface of a conductive film, said apparatus comprising: a polishing table having a polishing surface; a top ring configured to hold the workpiece, and being configured to press the workpiece against the polishing surface to polish the conductive film; an optical sensor configured to monitor the polishing state of the conductive film by emitting multi-wavelength light toward the conductive film of the workpiece held by the top ring, receiving reflected light from the conductive film and dispersing the reflected light into a spectrum to select a plurality of reflected lights, each reflected light of the plurality of reflected lights having a different specified wavelength from each other reflected light of the plurality of reflected lights, and measuring a change in the reflectance of said each reflected light of the plurality of reflected lights having a different specified wavelength to detect a thickness of the conductive film; and a control section configured to control a pressure at which the workpiece is pressed on the polishing surface.