Patent ID: 6942543

Claim:
A substrate polishing apparatus for polishing a surface of a substrate by a relative movement between the substrate and a polishing member, comprising: a table, the polishing member fixed on a surface of the table, a substrate support member for pressing the substrate onto the polishing member, an optical system for irradiating a surface of the substrate with a light of irradiation through a through-hole disposed in the polishing member and for receiving a reflected light reflected from the surface of the substrate, and a film-thickness monitoring device for monitoring a status of polishing by the optical system; wherein a valve to regulate a supply of a liquid is provided in a liquid passageway communicated with the through-hole so that the liquid, to be discharged from a liquid-feeding opening, flows in a direction generally perpendicular to a surface of the substrate, and the optical system comprises an optical fiber for irradiating the surface of the substrate with light in such a manner that the light is able to reach the surface of the substrate through a portion of the liquid flowing perpendicular to the surface.