Interferometrie tenkých vrstev

Abstract

Thin-film systems play a crucial role in present modern technologies. With the view of their application and practical usage, the knowledge of the basic optical parameters, such as thickness, index of refraction and extinction coefficient, is necessary. These parameters are often determined by the indirect methods when the suitable models are combined with the experimental methods. The substrate – thin film – superstrate system is studied in the presented thesis. The substrate is constituted by the silicon single crystal wafer; thin film is represented by silicon oxide (created by so called dry oxidation methods) and air represents the superstrate. Spectral interferometry and spectral reflectometry are used for the thin-film systems measurement. A white-light Michelson interferometer and normal incidence of light are used for the spectral interferometric technique. Spectral reflectometry uses a commercial spectrophotometer Shimadzu UV-3600 (the wavelength range 185 – 3300 nm). This thesis is focused on new methods of thin-film thickness determination. A phase retrieval method from the spectral interferograms by a windowed Fourier transform and wavelet transform are applied. This method enables much simpler processing of the interference spectra because one can avoid to deal with the relatively complicated envelope function representing the visibility. In the following part of the thesis, the effect of the used reflectance model at the thin-film thickness determination is discussed. Next, a new alternative method of the reflectance measurement using the reference sample replacing of the reference mirror is presented and discussed. Further, a new method of thin film thickness determination employs a simple relation between the thin film thickness and the wavelength corresponding with the tangent of the reflectance spectra and the envelope function.