Removal of C2F6 from a semiconductor process flue gas by a ferroelectric packed-bed barrier discharge reactor with an adsorber

The abatement of greenhouse gases from semiconductor processes is becoming important. Methane and/or nitrous oxide are continuously exhausted from the processes, and high concentrations of per-fluorocarbons (PFCs), such as NF 3, C2F6, SF6, and CF4, are exhausted during wafer etching and clean up of P ECVD (plasma enhanced chemical vapor deposition) chambers. The removal Of C 2F6 from a simulated semiconductor-process flue gas was studied using a hyb rid control system, consisting of a ferroelectric packed-bed barrier discha rge reactor and an adsorber. The barrier discharge reactor was composed of BaTiO3 ferroelectric pellets and was operated with ac voltages at 60 Hz. Th e adsorber was either artificial zeolite or activated carbon. Simulated flu e gases consisted of N-2 or N-2-H2O mixtures with 1000 to 3000 ppm C2F6. Th e experiments showed: 1) the removal efficiency for C2F6 increases with inc reasing applied voltage until the threshold for spark formation is reached; 2) the removal efficiency increases at lower temperatures and by use of th e hybrid system, and decreases with increasing gas now rate; 3) humidity si gnificantly reduces the reactor's efficiency as a result of the energy draw n from the discharge for H2O molecule dissociation; 4) trace CF4, CO, NO2, N2O, and SiF4 are by-products of the control system; and 5) about 13.5 g of C2F6 is decomposed by 1 kWh of input electrical power to the hybrid system . CF4 is a by-product from C2F6 removal, while the other by-products come f rom etching the reactor's glass wall (SiO2) by fluorine released from C2F6 removal.