Film-thickness difference estimating method and optical film-thickness measuring apparatus

Abstract

This invention provides a method and an optical film thickness measurement device for estimating the film thickness difference of a plurality of films constituting a workpiece during grinding. The film thickness difference estimation method involves grinding a workpiece having a first film and a second film made of different materials, while generating a plurality of measurement spectra of reflected light from the workpiece during the same grinding time. Each of the plurality of measurement spectra is input into a classification model, and the classification model outputs a classification result indicating that each of the plurality of measurement spectra is classified into either a first group or a second group. The measurement spectra classified into the first group and the measurement spectra classified into the second group are input into a film thickness estimation model. The film thickness estimation model outputs the estimated film thickness of the first film and the estimated film thickness of the second film of the workpiece during the aforementioned grinding time. By subtracting the estimated film thickness of the second film from the estimated film thickness of the first film, the estimated film thickness difference between the first film and the second film of the workpiece during the aforementioned grinding time is calculated.

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