Patent attributes
A polishing apparatus which can reduce scratches that are generated on a surface of a substrate during polishing by detecting a foreign matter such as a fragment of the substrate on an inner circumferential surface of a retaining ring for holding an edge portion (peripheral portion) of the substrate is disclosed. The polishing apparatus includes a polishing table having a polishing surface, and a top ring having a substrate holding surface to hold a beck surface of a substrate and a retaining ring to retain the substrate on the substrate holding surface. The top ring holds the substrate and presses the substrate against the polishing surface. The polishing apparatus includes an imaging device configured to image an inner circumferential surface of the retaining ring, and an image processor configured to process an image obtained by the imaging device to judge whether there is a foreign matter on the inner circumferential surface of the retaining ring.
