Polishing apparatus and polishing method

Abstract

This invention provides a grinding apparatus that can accurately measure film thickness while keeping the liquid used in film thickness measurement clean. The grinding apparatus includes: a grinding pad 2 having a grinding surface 2a; a grinding head 1 for pressing a workpiece W onto the grinding surface 2a; a grinding stage 3 for supporting the grinding pad 2; an optical sensing head 22 that guides light to the workpiece W through a through-hole 34 formed in the grinding pad 2 and receives reflected light from the workpiece W through the through-hole 34; a tank 50 for storing liquid supplied to the through-hole 34; a liquid circulation line 45 for circulating the liquid between the through-hole 34 and the tank 50; and an ultraviolet irradiation head 55 for irradiating the liquid flowing in the liquid circulation line 45 with ultraviolet light to sterilize the liquid.

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