METHOD AND APPARATUS FOR MEASURING INTERVAL

摘要

PROBLEM TO BE SOLVED: To measure the film thickness of a resist film even on the occurrence of membrane interference and the interval between various members such as the interval between a mask substrate and a glass substrate.

SOLUTION: A first laser beam LA emitted from a first laser beam source 10A and a second laser beam LB emitted from a second laser beam source 10B having oscillation wavelengths different from each other are joined to each other by a dichroic mirror 3 and made incident onto a resist film 5 from an oblique direction. Even if one wavelength component of two wavelength components contained in resist-film surface reflected light L1 reflected at the surface of the resist film 5 and resist-film backside reflected light L3 reflected at its backside has caused membrane interference, a photo-detector 22 detects light of the other wavelength component. The film thickness of the resist film 5 is measured on the basis of the interval DR between positions P1 and P3 of light reception detected by the photo-detector 22.

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