Patent ID: 7270594

Claim:
A polishing apparatus comprising: a polishing table having a polishing surface thereon; a top ring for pressing a workpiece against said polishing surface, said top ring having a retainer ring for holding an outer circumferential edge of the workpiece and a chucking plate to hold the workpiece on a lower surface thereof; a vertically moving mechanism operable to vertically move said top ring; a bracket vertically movable together with said top ring; a stopper adjustable in vertical position to prevent downward movement of said bracket; a sensor for detecting a distance between said stopper and said bracket; and a control unit operable to adjust said stopper in vertical position when the workpiece held on the lower surface of said chucking plate is brought into contact with said polishing surface while a lower surface of said retainer ring of said top ring is located at a predetermined height from said polishing surface so that the distance between said stopper and said bracket is equal to a difference between a height of the lower surface of said retainer ring from said polishing surface at the time of polishing and said predetermined height.