Method of checking for foreign matter on a substrate with light of maximum reflectivity for that substrate

Abstract

A method and an apparatus for checking and detecting foreign matter on the surface of a semiconductor substrate with high and stable sensitivity, and with high precision. The respective reflectivities at which light of various wavelengths within a wide wavelength range is reflected from each multi-layer thin film substrate are measured, and light of a wavelength at which the light is reflected at a local-maximum reflectivity is selected as monitor light for foreign matter checking with respect to each substrate. The apparatus comprises, as a light source, a light source for generating light within a wide wavelength range and a filter for narrowing the wavelength range of light so as to obtain monitor light which is to be radiated onto a substrate to check foreign matter. Variations in detection sensitivity due to slight variations in the thickness of deposited films on semiconductor substrates can be restrained to thereby realize foreign matter checking with stable sensitivity.

Dependencies are inferred from the claim text.