Patent ID: 7207862

Claim:
A polishing apparatus comprising: a polishing surface; a substrate holder for holding a substrate and pressing a surface of the substrate against said polishing surface while said substrate holder and said polishing surface move relative to one another so as to polish the surface of the substrate; a camera for acquiring color image data of a region of said polishing surface; an image processor for determining whether or not foreign matter exists on said polishing surface based on a color condition of the color image data as acquired by said camera, said image processor including (i) identifying means for identifying whether or not a color of each point in the color image data as acquired by said camera is identical with a color of foreign matter, which color of foreign matter has been previously stored as a reference color, and (ii) determination means for determining existence of foreign matter when a total area of points, each of which corresponds to the reference color, exceeds a predetermined threshold value.