Patent ID: 7021991

Claim:
A polishing apparatus comprising: a polishing table having a polishing surface, said polishing table being rotatable about an axis; a top ring for holding and rotating a workpiece to be polished and pressing a surface of the workpiece against said polishing surface on said polishing table, said top ring having a holding surface for holding the workpiece thereon and a guide ring disposed around said holding surface of said top ring for retaining the workpiece; a film thickness measuring device embedded in said polishing table, said film thickness measuring device including: a light source facing the surface of the workpiece held by said top ring for applying light having a predetermined wavelength to a surface of the workpiece, a spectroscope for separating light reflected from the surface of the workpiece, a sum of radial lengths of said light source and said spectroscope being larger than a radius of said holding surface of said top ring, and a charge coupled device array for capturing light separated by said spectroscope, wherein said film thickness measuring device is configured to scan an entire surface of the workpiece according to rotation of said top ring and said polishing table; and a controller operable to analyze information captured by said charge coupled device array over an entire surface of the workpiece to obtain a film thickness at a desired point on the surface of the workpiece.