Removal of C2F6 from semiconductor process flue gases by ferro-electric packed-bed barrier discharge reactor-adsorbent hybrid systems

Removal of greenhouse gases from semiconductor process flue gas is becoming a significant problem since not only methane and/or nitrous oxide are exhausted but also high concentrations of fluoride and para-fluorocarbons (PFCs) such as NF₃, C₂F₆ , SF₆, and CF₄, are exhausted during the wafer etching or PECVD chamber cleaning processes. In this work, the removal of C₂F₆ from a simulated semiconductor process flue gas by a ferro-electric packed bed barrier discharge reactor-adsorbent hybrid system is experimentally investigated. The hybrid system consists of near-spherical shaped BaTiO₃ ferro-electric packed bed (specific dielectric constant ε_s =660 to 10⁴) barrier discharge reactor operated at 60 Hz commercial frequency and 1 mm near-spherical shaped artificial zeolite adsorbent bed. PFCs, such as C₂F₆, are diluted in N₂ or N₂-H₂O gases in the level of 1000 to 3000 ppm. The experimental results show that: (1) removal efficiency increases with increasing applied voltage until the threshold for spark formation is reached; (2) removal efficiency increases with increasing reactor gas cooling and decreases with increasing gas flow rate; (3) humidity significantly reduces the reactor efficiency because of the energy drawn from the discharge for H₂ O molecule dissociation; (4) trace CF₄, CO, NO₂ , N₂O and SiF₄ were the only by-products observed in this experiment; and (5) about 13.5 g of C₂F₆ was decomposed by 1 kW of input electrical power