Film thickness measuring apparatus, film thickness measuring method and wafer polishing system measuring a film thickness in conjunction with a liquid tank

摘要

A light interference-type film thickness measuring mechanism 24 measures a film thickness by irradiating a light emitted from a light transmission portion on to the bottom surface of a wafer W held by a wafer holding head 8 and receives the reflected light and. A cleaning mechanism 26 includes a cleaning fluid tank 27 a top surface of which is opened and arranged in the vicinity of the bottom surface of the wafer; a light transmission portion 50 formed at the bottom portion 48 of the tank 27; a wafer cleaning nozzle 40 spraying the cleaning fluid on the measuring points at the bottom surface of the wafer; a light transmission portion cleaning nozzle 44 spraying the cleaning fluid on the light transmission portion 50 and cleaning fluid supply means for supplying cleaning fluid to these nozzles.