STUDIES ON MEASUREMENTS OF RADICALS IN GAS PHASE USING SPECTROSCOPY TECHNIQUES

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(1) CFx (X=1-3), SiHx (X=1-3) and Si radicals in plasmas excited by some plasma sources were investigated by infrared diode laser absorption spectroscopy and various kinds of laser spectroscopy technologies, and the behaviors of radicals was clarified. The techniques to control the density and compositon of CFx (X=1-3) radicals were developed.(2) A set of cross action data on electron-impact dissociation of reactive molecules into neutral radicals was obtained. Ionic species dissociatively scattered from the surface were measured when the ions were incident on the surface. The surface reaction of CF_2 radicals for etching processes were clarified.(3) The density of H radicals in a parallel plate RF silane plasma were measured by laser fluorescence technique, namely two-photon excitation at 205nm and the behavior of H radicals was clarified.(4) The role of H radicals in the formation of poly-crystalline Si films at a low temperature was investigated and it was clarified that H radicals playd an important role. The surface of Si exposed to CF_4 plasma was observed by phase-modulated FT-IR spectroscopy developed in this study. It was found that the particles grew through electrostatic forces and/or attractive force in the methane plasma and the spatial arrangement of particle was formed. The mechanism of this pseudo two-dimensional alignment was investigated.(5) It was found that the key species contributing to the particle nucleation were short-life radicals, especially SiH_2 and they participated many times in the initial growth process using laser and probe techniques.(6) Space-and time-resolved emission spectroscopy was applied to obtain the information on the behavior of the plasma structure at a capacitively coupled plasma. It was found that the sheath width increased with increasing the dissipated power. Moreover, it was confirmed that the synergism in the reaction between O and O^- produced in abundance in O_2 plasma.