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.