Optics of Inhomogeneous Thin Films with Defects: Application to Optical Characterization

Abstract

This review paper is devoted to optics of inhomogeneous thin films exhibiting defects consisting in transition layers, overlayers, thickness nonuniformity, boundary roughness and uniaxial anisotropy. The theoretical approaches enabling the inclusion of these defects into formulae expressing the optical quantities of these inhomogeneous thin films are summarized. These approaches are based on the recursive and matrix formalisms for the transition layers and overlayers, averaging of the elements of the Mueller matrix using local thickness distribution or polynomial formulation for the thickness nonuniformity, scalar diffraction theory and Rayleigh-Rice theory or their combination for boundary roughness and Yeh matrix formalism for uniaxial anisotropy. The theoretical results are illustrated using selected examples of the optical characterization of the inhomogeneous polymer-like thin films exhibiting the combination of the transition layers and thickness nonuniformity and inhomogeneous thin films of nonstoichiometric silicon nitride with the combination of boundary roughness and uniaxial anisotropy. This characterization is realized by variable angle spectroscopic ellipsometry and spectroscopic reflectometry. It is shown that using these optical techniques, the complete optical characterization of the mentioned thin films can be performed. Thus, it is presented that the values of all the parameters characterizing these films can be determined.

Optical characterization of inhomogeneity of polymer-like thin films arising in the initial phase of plasma-enhanced chemical vapor deposition

“…During this separate characterization, the thin NOL layer was considered as an overlayer originating from air exposure, which would not have occurred if the polymer-like thin film had been deposited immediately after cleaning procedure. The reliability of the determined optical constants of the transition layer is supported by the strong agreement with our earlier work [35] , [53] , [54] . The only parameter related to the transition layer determined during the processing of data for samples with films was its thickness.…”

Nanostructuring of Sno2 Thin Films by Associating Glancing Angle Deposition and Sputtering Pressure for Gas Sensing Applications

“…On the other hand, films deposited at 6.10 -3 mbar (C6 and I6) show minor interference fringes indicating inhomogeneity in the films. As mentioned in work of Ohlídal et al [34], this inhomogeneity is due to surficial and inner roughness of the films. From Figure 3 (a), it can be underlined that there is no absorption edge shift for the C3 film whatever the annealing temperature.…”

Nanostructuring of SnO2 Thin Films by Associating Glancing Angle Deposition and Sputtering Pressure for Gas Sensing Applications

“…On the other hand, films deposited at 6 × 10 −3 mbar (C6 and I6) show minor interference fringes, indicating inhomogeneity in the films. As mentioned in the work of Ohlídal et al [34], this inhomogeneity is due to the surficial and inner roughness of the films. From Figure 3a, it can be underlined that there is no absorption edge shift for the C3 film whatever the annealing temperature.…”