Photothermal elastic vibration spectra of SiO2 film on Si

The silicon-dioxide film on the silicon substrate (SiO₂ / Si) samples were investigated by the photothermal elastic vibration method. The photothermal elastic vibrations in two-layer rectangular plates were optically excited by the focused laser beam and the generated vibrations were measured with a sensitive optical probe (the double-heterodyne interferometer). The photothermal elastic vibrations spectra were measured and analyzed for different types of Si substrate (with and without the SiO₂ films) vs the frequency of modulation of the excitation laser. This investigation is important for analysis of the influence of the different technological processes to the vibrations of the optically driven micromechanical structures, i.e. how the technological processes change the characteristics of micromechanical structures.