The structure is reflected in vibrational spectra. Due to high precision, selleckchem Raman spectroscopy can detect small deviations of molecular structure. The other advantage of this experimental technique is its nondestructive character. Examples of application of Raman spectroscopy for investigation of structural deviations are: analysis of mechanical stress distribution [5] and monitoring structural changes like densification caused by technological processes [6].This work compares Raman spectra measured for three made from high-�� materials thin films deposited on silicon substrate. The first one, hafnium oxide, was already used for fabrication of CPU devices [7]. Two others, lanthanum-lutetium oxide and gadolinium-silicon oxide are candidates for application in electronic devices.

Raman spectra of high-�� films are compared with data obtained for silicon dioxide layer.2. ExperimentalSamples. As a reference sample, Si wafer covered with SiO2 layer was used. Its manufacturing was already presented in the literature [8]. Hafnium oxide (HfO2) films were prepared with atomic layer deposition (ALD) technique. As substrates, four silicon (Si) wafers were used. The orientation of crystallographic axes was <100>. The wafers were covered with 6nm thick base silicon dioxide film prior to deposition of HfO2. Three samples were subject to rapid temperature annealing (RTA) at 400��C, 600��C and 800��C. The fourth sample was used without thermal treatment (hereafter called as-deposited). Cooperation in respect to manufacturing of HfO2 samples was covered by the Institute of Electron Technology and Institute of Physics of Polish Academy of Sciences.

Samples with gadolinium-silicon oxide (GdSiO) and lanthanum-lutetium oxide (LaLuO3) were manufactured at Gesellschaft f��r Angewandte Mikro- und Optoelektronik (AMO GmbH, Niemcy). In the case of GdSiO a two-step procedure was used. In the first step, Gd2O3 layer was deposited on Si substrate. In the second step, RTA was used to achieve GdSiO structure. RTA process was performed at 900��C during 60s.2.1. Apparatus The selection of excitation wavelength is of key importance for the Raman study of dielectric layers. In the case of visible excitation, the signal generated in thin dielectric layer can be even masked by multiphonon Raman scattering generated in Si substrate [9].

Due to this large background, Raman scattering is often treated as useless in the study of thin dielectric layers [10]. Deep-ultraviolet excitation significantly reduces the penetration depth of excitation light into the silicon substrate in AV-951 comparison with standard visible excitation. The reduction of this penetration depth decreases the background intensity to negligible values. As a result, the Raman scattering from dielectric layer appears in the spectrum.