Substrate polishing apparatus and film thickness calculation method

Abstract

A substrate grinding apparatus and a film thickness calculation method for accurately measuring the film thickness of a substrate during the grinding process. The substrate grinding apparatus includes: a grinding table equipped with an eddy current sensor and configured to rotate; a grinding head opposite the grinding table and configured to rotate, and capable of mounting a substrate on the surface of the grinding head opposite the grinding 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 multiple tracks on the substrate; determine multiple corresponding points equidistant from the center of the substrate on the multiple tracks; compare the values ​​of the output signal of the eddy current sensor at the determined multiple points; 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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