Application of white-light scanning interferometer on transparent thin-film measurement.

A method to measure thin-film thickness, refractive index, and dispersion constants based on white-light interferometry is described. The thin-film property is retrieved from the Fourier amplitude of the white-light correlogram. The sources of errors in Fourier amplitude, which include the accuracy of wave number, light source variation in time, and illumination nonuniformity, are investigated. With all these errors reduced, the film thicknesses and refractive indices of four samples measured by white-light interferometry are within 1% of the ellipsometry results.