Vapor-Phase Preparation of Carbonaceous Materials Using Activated Fluorine Species

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The aim of this research is to develop a novel method for vapor-phase preparation of carbonaceous materials at temperatures lower than those used in conventional methods. Activated fluorine species was obtained by decomposition of nitrogen trifluoride (NF_3) in plasma, and was used to activate the decomosition process of hydrocarbon. The decomposition mechanism in the presence of NF_3 was analyzed by quadrupole mass spectroscopy (QMS). Major findings are as follows :1.Vapor-phase preparation of carbonaceous materialsBenzene was used as a carbon source for thin film. In the presence of NF_3, deposition rate of carbonaceous film increased significantly when compared with that in the absence of NF_3. Carbonaceous thin films can be obtained even at a low temperature of 400ﾟC.Glass plate substrates gave carbonaceous films of flat surface, wheresas nickel plate substrates resulted in rough surface. When the temperature of the substrate was increased, deposition rate decreased. Carbonaceous films with best quality was obtained by vaporphase reaction at 700ﾟC.When the plasma power was increased, the crystallinity of the resulting films increased, whereas the deposition rate decreased.2.Analysis by QMSQMS analysis revealed that activated fluorine species was released by decomposition of NF_3, and this active species substitutes the hydrogen of benzene to form fluorobenzene. Flurobenzene decomposes more easily than benzene, resulting in the observed enhancement of deposition rate.