| Summary: | 碩士 === 國立中央大學 === 環境工程研究所 === 89 === Due to rapid growth in semiconductor manufacturing process such as etching and chemical vapor deposition (CVD) clean over these years, innovative technologies are needed to reduce the corresponding increase in chemicals used like perfluorocompounds (PFCs) that would be emitted to the atmosphere. PFCs are a cause for concern because of their large global warming potentials relative to CO2 and of their long lifetimes in the atmosphere, often thousands of years. To meet Kyoto agreement requirements, the strategies available for controlling PFCs emissions include applying alternative chemicals, recovery/recycle systems, process optimization and abatement technologies nowadays. In this study, laboratory-scale plasma reactors (parallel plate reactor and coaxial reactor packed with BaTiO3) have been set up to evaluate the removal efficiency for CF4, the most stable species of PFCs. The operating parameters including applied voltage, applied frequency, gas composition, gas residence time and input power were also investigated. The experiments demonstrated that electrodes distances, electric field, applied voltage, gas residence time and input power relate to each other in the parallel plate reactor and 33.5% CF4 removal efficiency could be achieved under 2.0 cm electrodes distance and input power 99 Watt. As for the coaxial reactor packed with 30 cm BaTiO3, the CF4 removal efficiency reaches 48% due to the higher power deposition than that of parallel plate reactor. Adding hydrocarbon C2H4 into the influent gas stream would enhance CF4 removal efficiency to 42.6% and 66.6% for parallel plate reactor and coaxial reactor, respectively. At the same time, the major end products detected by FTIR include CO2, CO and H2O.
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