Simultaneous measurements of thin-film thickness and refractive index .. by dispersive white-light interferometry

A dispersive method of white-light interferometry for measuring the tomographical thickness profile of a thin-film layer through a Fourier-transform analysis of a spectrally-resolved interference signal is proposed. The refractive index is also determined without prior knowledge of the geometrical thickness of the film layer. In contrast with standard white-light scanning interferometry, dispersive white-light interferometry generates the spectral distribution of interferograms directly by means of dispersive optics without mechanical depth scanning. Therefore, the proposed method in this paper is well suited for in-line 3-D inspection of dielectric thin-film layers, particularly for the semiconductor and flat-panel display industry, with high immunity to external vibration and high measurement speed.