Method of producing a model for estimating film thickness of workpiece, method of estimating film thickness of workpiece using such a model, and computer-readable storage medium storing program for causing computer to perform the methods

A method of producing a model capable of reducing an influence of spectral variation of reflected light from a workpiece, such as a wafer, and capable of determining an accurate film thickness is disclosed. The method includes: determining sample features representing features of sample spectra of reflected lights from a sample having a film; obtaining similarities by calculating a similarity between each of the sample spectra and a representative spectrum; and producing a film-thickness estimation model by performing machine leaning using training data including the sample features, the similarities, and film thicknesses corresponding to the sample spectra.