Spectral interferometric technique to measure the ellipsometric phase of a thin-film structure

A two-step white-light spectral interferometric technique is used to retrieve the ellipsometric phase of a thin-film structure from the spectral interferograms recorded in a polarimetry configuration with a birefringent crystal. In the first step, the phase difference between p- and s-polarized waves propagating in the crystal alone is retrieved. In the second step, the additional phase change that the polarized waves undergo on reflection from the thin-film structure is retrieved. The new method is used in determining the thin-film thickness from ellipsometric phase measured for SiO(2) thin film on a Si substrate in a range from 550 to 900 nm. The thicknesses of three different samples obtained are compared with those resulting from polarimetric measurements, and good agreement is confirmed. (C) 2009 Optical Society of America