INFRARED ELLIPSOMETRY INVESTIGATION OF SIOXNY THIN-FILMS ON SILICON

The dielectric function <(epsilon)over tilde>(<(epsilon)over tilde> = epsilon(1) + i epsilon(2)) of silicon oxynitride films deposited on si licon wafers by dual ion-beam sputtering is determined by infrared ell ipsometry between 580 and 5000 cm(-1). The phase-separation model is u nable to reproduce the experimental data. The dependence of <(epsilon) over tilde> on stoichiometry is analyzed with the microscopic Si-cente red tetrahedron model. The random-bonding model with five SiO4-jNj (j = 0.4) tetrahedra gives a good description of the spectra, provided th e dielectric function of the mixed tetrahedra is carefully chosen. (C) 1996 Optical Society of America