Spectral ellipsometry of binary optic gratings

Abstract

The coupled wave method (CWM) has been applied to the description of electromagnetic wave propagation in binary optic gratings. The electromagnetic field and the permittivity profile are expanded into two-fold Fourier series. The reflection coefficients of 2D periodical structures have been specified and the ellipsometric angles of the shapes discussed have been computed. The theoretical results are compared with experimental data obtained on SiO2 square dots on Si substrate. The measurements were performed using computer controlled four zone null ellipsometer in spectral range from 240 nm to 700 nm. The influence Of SiO2 ultrathin oxidation layer and thickness of dots on spectral ellipsometric angles is also discussed.