Method of measuring refractive index of thin film and refractive index measuring apparatus therefor

摘要

A method of measuring the refractive index of a thin film is composed the steps of: (a) forming a dielectric thin film which is transparent, uniform and geometrically and optically identical, on each of a first substrate and a second substrate, with the refractive indexes of the first substrate and the second substrate being different; and (b) measuring the reflectivities of the first and second substrates, each bearing the dielectric thin film thereon, with the application of a light with an identical wavelength to the two substrates, thereby measuring the refractive index of the dielectric thin film. A refractive index measuring apparatus for conducting the above method is composed of a thickness measuring optical system for sequentially guiding a luminous flux emitted from a light source to a first monitor substrate and a second monitor substrate on both of which a dielectric thin film is to be formed, and then guiding two light rays respectively reflected by the first and second monitor substrates to a light receiving unit; and an arithmetic unit for calculating the refractive index of a dielectric thin film from two intensity signals from the light receiving unit.