Analysis of Interfacial Phenomena between Plasmas and Solid Surfaces with Microstructure

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Firstly, fluxes of radicals transported from plasmas to substrates were measured as the boundary condition for surface reactions. The radicals measured are including atomic species such as H,O and N,and molecular species such as SiH_2 and CF_2. Secondly, a new method named FT-IR phase modulated spectroscopic ellipsometry (PMSE) has been developed for in-situ surface diagnostics By this method chemical bonding states on the surface are detected with a high sensitivity.By using these method, surface reactions in the etching of Si wafer was investigated as the first example. A thin fluorinated overlayr was detected on a substrate placed on the self-biased RF electrode, which was irradiated by ions bombarding with appreciable energy in addition to neutral radicals. On the other hand, polymer formation was observed on a substrate placed on the grounded electrode with less ion bombardment. These phenomena are suggested to occur at the bottom and the side wall, respectively, of a micro-trench on a patterned substrate. The effect of ion bombardment are going to be investigated in detail by using a mass spectrometer placed at the bottom of a substrate with micro channels of high aspect ratios.In the other example, roles of SiH_2 and H radicals were studied in the deposition of amorphous and polycrystalline Si films. The characteristics of deposited films were analyzed by in-situ spectroscopic ellipsometry. As an important conclusion, it has been recognized that hydrogen atoms work both in the etching of amorphous tissue and in the chemical annealing of stressed structures for enhancing the crystal growth.Through these studies some methods have been considered for increasing the spatial resolution in the gas-phase and surface diagnostics. With the improved resolution this project has been continued for better understandings of the interaction of plasmas with micro-structured substrates.