Decomposition and polymerization of perfluorinated compounds in microwave-excited atmospheric pressure plasma

Decompositions and polymerizations of perfluorinated compounds gases were demonstrated employing atmospheric pressure plasmas with continuous-wave microwave excitations. The atmospheric pressure plasma was generated at a low gas temperature of 520 K. Spherical-shaped particles of approximately 50-120 nm in diameter were synthesized in CF4/He and C4F8/He plasma on Si substrate with dc voltage biasing, which was set in the plasma downstream region. The gas temperature in plasma was important to generate particles because particles were not generated at a high gas temperature of 850 K. The particles were determined to consist of carbon and fluorine atom composition from an energy dispersive x-ray spectroscopy. Furthermore, the effect of H-2 addition on the CF4/He plasma was investigated. The decomposition efficiency of CF4 was increased with H-2 addition and obtained over 80% without emissions of carbon dioxide. (c) 2005 American Institute of Physics.