OPTICAL FUNCTIONS AND TRANSPARENT THIN-FILMS OF SRTIO3, BATIO3, AND SIOX DETERMINED BY SPECTROSCOPIC ELLIPSOMETRY

A procedure is presented for accurately determining the thickness, opt ical functions, and surface-roughness characteristics of thin-film ins ulators from two-channel spectroscopic polarization-modulation ellipso metry data. For films with minimal surface roughness, the optical func tions can be determined over the entire measured spectrum; for rougher films, the analysis of the spectroscopic ellipsometry data yields mea ningful values of the optical functions only in the transparent region . In general, the films must be transparent in a given range of wavele ngths sampled by the ellipsometer so that at least two interference os cillations can be observed. The use of the procedure is illustrated wi th the determination of the optical functions of SrTiO3 and BaTiO3 thi n films grown on MgO, and of SiO(x) films grown on Si. For SrTiO3 and BaTiO3, the thin-film results are compared with the measured optical f unctions of the respective bulk materials.