Innovative Surface Wave Plasma Reactor Technique for PFC Abatement

Abstract

Application of surface wave plasmas as an innovative technology for the destruction and removal of perfluorocompounds (PFC) emanating from semiconductor fabrication tools is demonstrated. The destruction of parts per thousand (ppt) concentrations of hexafluoroethane, C2F6, in oxygen and natural gas mixtures has been investigated as a function of microwave power in a low-pressure plasma reactor at 11.3 Torr. Effluent analysis included the determination of destruction and removal efficiencies (DRE) and product distributions by Fourier transform infrared spectroscopy and mass spectrometry. Destruction and removal efficiences of up to 99.6% for C2F6 were achieved using applied microwave powers from 500 to 2000 W, which corresponded to millisecond range residence times within the plasma. Product analysis indicated that hexafluoroethane conversion was limited to low molecular weight gases such as CO2, CO, COF2, H2O, and HF. CF4 was not produced as a plasma byproduct in any significant quantities. These investigations indicate that surface wave plasma destruction of perfluorocompounds at the point of use is a viable nonintrusive abatement technology for application to semiconductor manufacturing tools.

Abatement of Sulfur Hexafluoride Emissions from the Semiconductor Manufacturing Process by Atmospheric-Pressure Plasmas

“…20 Iio and coworkers 21 used mass spectrometry in a dual electron beam device and measured the energy dependence of the partial cross sections of electron-impact dissociation of SF 6 into the neutral radicals SF, SF 2 , and SF 3 from threshold to 200 eV. The dissociation products SF 4 and SF 5 were below the detection limit of their system. However, SF 5 seems more likely to be generated compared with SF x (x Ͻ 3) because of its low threshold energy.…”

“…This packing effect leads the CPC reactor to a constant level of removal efficiency after a long-time operation. Figure 12 illustrates possible pathways for SF 6 4 are the intermediates. These byproducts are toxic or caustic, and they must be removed from the gas streams before emission into the atmosphere.…”

“…Applying nonthermal plasmas for PFC abatement is, therefore, technologically feasible. Various nonthermal plasma technologies, including surface wave plasma, 4,5 arc discharges, 6 dielectric barrier discharge (DBD), 7 combined plasma catalysis (CPC), 8 radio frequency (rf), 9 microwave, 10 and inductively coupled plasma (ICP) 11 have been investigated in recent years as alternate technologies for abating PFCs. With ICP, 95% destruction efficiency was achieved for the gas stream containing 50 sccm SF 6 and 140 sccm H 2 O (g) , while 85% destruction efficiency was obtained for the gas stream consisting of 50 sccm SF 6 and 100 sccm oxygen (O 2 ).…”

Plasma Flame Sustained by Microwaves and Burning Hydrocarbon Fuel: Its Applications

“…Microwave plasmas operated at the atmospheric pressure, especially waveguidebased plasma, have been subject of increased attention during the last decade (Margot, 2001;Moisan et al, 2001). Such an interest comes from their potential and actual use in various applications, including excitation sources for elemental analysis, lighting, and purification or remediation of gas effluents detrimental to the environment (Hartz et al, 1998;Woskov & Haddi, 1999). The microwave plasma torch can easily be made by modifying typical household microwave ovens as inexpensive method .…”

Abatement of perfluorocompounds with microwave plasma in atmospheric pressure environment

“…Recently, the plasma technologies used in the abatement of perfluorocompounds include dielectric barrier discharges, inductively coupled plasma and microwave plasma [5][6][7][8][9][10][11][12][13][14][15]. Microwave plasma has high electron temperature and high electron density which is more efficient to perfluorocompounds abatement than other plasma technology.…”