Abstract
Perfluorocompounds (PFCs) like CF4 are used in many semiconductor fabrication processes. However, Global Warning Potential (GWP) values of PFCs are very large. It is difficult to decompose CF4 because of its stability. Oxygen anion (O-) was used for the decomposition of CF4 in this study because a large quantity of O- ions can be emitted from 12CaO·7Al2O3 (C12A7) easily. Ab initio calculation was used to evaluate the potential energy surfaces and the reaction barriers of the O- + CF4 reaction in the previous work. Although the SN2 type reactions, such as the CF3O- +F, are exothermic, the reaction barrier was calculated to be about 222 kJ/mol at the UMP2/6-31+G** level of theory. However, the result indicates that CF4 can be decomposed if we add the kinetic energy more than 222 kJ/mol to O-. We investigated the decomposition of CF4 by the O- ions with guided-ion beam tandem mass spectrometry in this study and it was confirmed that CF4 was decomposed practically. Next, we constructed the experimental apparatus by using C12A7 tube for the decomposition of CF4 to evaluate the possibility for the practical use. 15% CF4 decomposition was achieved by the C12A7 tube reactor.
