The Ellipsometrical Analysis of External Reflection of Light on Superficial Films on Solid Substrates

Abstract

The ellipsometrical analysis of the external specular reflection of light on nonabsorbing superficial films allows us to know factors which influence the ellipsometric measurement of the analyzed system. For optical nonabsorbing superficial films the curves ∆=f(d f) and Ψ=f(d f) are periodical, while the curves ∆=f(Ψ) are closed. The paper presents observations on the dependence of the ellipsometric parameters ∆ and Ψ on d f. The analysis of the periodicity of these curves allows us to correctly determine the film thickness for thicknesses greater than d min. The value of d min depends on the refractive index n f of the surface film, the incidence angle φ 0 and the wavelength λ of the incident radiation. The dependence of d min on n f , φ 0 and λ is analyzed. From the curve shape we can draw conclusions with respect to the domain of small errors, allowing us to correctly determine the thickness and refraction index of superficial films.