V. N. Kruchinin

Optical properties of the HfO 2 − x N x and TiO 2 − x N x films prepared by ion beam sputtering

Optical characteristics of the HfO2 − xNx and TiO2 − xNx films obtained by reactive ion beam sputtering have been investigated by spectral ellipsometry. The chemical composition of the films was determined using X-ray photoelectron spectroscopy. The nitrogen content in the oxynitride films (determined by the N2/O2 ratio in the gas mixture during synthesis) reached ≈9 at % for TiO2 − xNx and ≈ 6 at % for HfO2 − xNx. It is found that the dispersion relations n(λ) and k(λ) for the TiO2 − xNx films change from those characteristic of titanium dioxide to those typical of titanium nitride with an increase in the nitrogen content from 0 to ≈9 at %. The optical parameters of the HfO2 − xNx films depend weakly on the nitrogen content in the range 0–6 at %.

Dispersion of the refractive index in high-k dielectrics

A brief review of the optical properties of oxide materials that are used at present as dielectrics in modern microelectronics is presented. Using spectral ellipsometry, dispersion dependencies for different materials are measured. A brief comparative analysis of different dielectric coatings is carried out. The results of our research will be useful in further studies of the properties of dielectrics, as well as in technologies that are employed in the development of new semiconductor instruments and devices.

Optical properties of the HfO2 − xNx and TiO2 − xNx films prepared by ion beam sputtering

Optical characteristics of the HfO2 − xNx and TiO2 − xNx films obtained by reactive ion beam sputtering have been investigated by spectral ellipsometry. The chemical composition of the films was determined using X-ray photoelectron spectroscopy. The nitrogen content in the oxynitride films (determined by the N2/O2 ratio in the gas mixture during synthesis) reached ≈9 at % for TiO2 − xNx and ≈ 6 at % for HfO2 − xNx. It is found that the dispersion relations n(λ) and k(λ) for the TiO2 − xNx films change from those characteristic of titanium dioxide to those typical of titanium nitride with an increase in the nitrogen content from 0 to ≈9 at %. The optical parameters of the HfO2 − xNx films depend weakly on the nitrogen content in the range 0–6 at %.

Optical properties of nonstoichiometric ZrO x according to spectroellipsometry data

Amorphous nonstoichiometric ZrOx films of different composition have been synthesized by the method of ion-beam sputtering deposition of metallic zirconium in the presence of oxygen at different partial oxygen pressures in the growth zone, and their optical properties have been studied in the spectral range of 1.12–4.96 eV. It is found that light-absorbing films with metallic conductivity are formed at the partial oxygen pressure below 1.04 × 10–3 Pa and transparent films with dielectric conductivity are formed at the pressure above 1.50 × 10–3 Pa. It is shown that the spectral dependences of optical constants of ZrOx films are described well by the corresponding dispersion models: the Cauchy polynomial model for films with dielectric conductivity and the Lorentz–Drude oscillator model for films with metallic conductivity.

Optical Properties of Nonstoichiometric Tantalum Oxide TaOx (x < 5/2) According to Spectral-Ellipsometry and Raman-Scattering Data

Optical properties of amorphous nonstoichiometric tantalum-oxide films of variable composition (TaOx, x = 1.94–2.51) in the spectral range of 1.12–4.96 eV, obtained by ion-beam sputtering-deposition of metallic tantalum at different partial oxygen pressures (0.53–9.09 × 10–3 Pa), have been investigated. It is shown by spectral ellipsometry that the character of dispersion of the absorption coefficient and refractive index in TaOx of variable composition suggests that light-absorbing films with dispersion similar to that in metals are formed at oxygen pressures in the growth chamber below 2.21 × 10–3 Pa, whereas transparent films with dielectric dispersion are formed at pressures above 2.81 × 10–3 Pa. According to the data of quantumchemical simulation, the absorption peak at a photon energy of 4.6 eV in TaOx observed in the absorptioncoefficient dispersion spectrum is due to oxygen vacancy. The peak in the Raman-scattering spectra of TaOx films with metallic dispersion at frequencies of 200–230 cm–1 is presumably related to tantalum nanoclusters.

The Possibility of Hemorheological Parameters as Precursors of Recurrent Strokes

The study aimed to evaluate the possibility of application of hemorheological parameters as precursors of recurrent strokes in cases of various pathogenetic forms of the disease.

Optical methods in diagnostics of liver fibrosis via blood observation

A possible application of optical methods (dielectrophoresis, spectral and imaging ellipsometry, Fourier- transform infrared spectroscopy, Raman spectroscopy) for the early diagnostics in studies of red blood cells and serum in patients with the diffuse liver disease, with varying degrees of fibrosis, has been evaluated. As experimentally confirmed, the combined optical methods significantly improve the sensitivity, specificity and accuracy index in the diagnosis of both severe fibrosis and slight ulterior liver fibrosis. The identified optical methods diagnostic potential can be efficiently utilized in noninvasive screening evaluation of the stages of diffuse liver disease of various genesis.

Ellipsometric in situ diagnostics of the growth of porous anodic oxide films on aluminum

An ellipsometric in situ study of the growth of porous aluminum anodic oxide films on aluminum substrate has been performed. Theoretical calculations have been carried out to interpret the experimental dependences of ellipsometric parameters; they made it possible to identify the most characteristic details of anodic oxidation. It is shown that the ellipsometric method allows one to control in situ in real time a number of important layer parameters: growth rate, porosity, depth uniformity, and the state of interface. The ellipsometric measurements have also revealed high sensitivity to the presence of metal nanoparticles both in the bulk of a layer and on its surface.