Substrate grinding apparatus and film thickness calculation method

Abstract

A substrate polishing apparatus and a film thickness calculation method for accurately measuring the film thickness of a substrate during the polishing process. The substrate polishing apparatus includes: a polishing table equipped with an eddy current sensor and configured to rotate; a polishing head opposite the polishing table and configured to rotate, and capable of mounting a substrate on the surface of the polishing head opposite the polishing table; and a control unit. The control unit is configured to: acquire waveform data of the output signal of the eddy current sensor as it passes through a plurality of tracks on the substrate; determine a plurality of corresponding points at equidistant distances from the center of the substrate from the plurality of tracks on the substrate; compare the values ​​of the output signal of the eddy current sensor at the determined plurality of points and find the minimum value among them; correct the waveform data based on the found minimum value; and calculate the film thickness on the surface of the substrate based on the corrected waveform data.

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