Decomposition of SF6 in an RF plasma environment

Sulfur hexafluoride (SF6)-contained gas is a common pollutant emitted during the etching process used in the semiconductor industry. This study demonstrated the application of radio-frequency (RF) plasma in the decomposition of SF6. The decomposition fraction of SF6[eta(SF6) (C-in-C-out)/C-in x 100%] and the mole fraction profile of the products were investigated as functions of input power and feed O-2/SF6 ratio in an SiO2 reactor. The species detected in both SF6/Ar and SF6/O-2/Ar RF plasmas were SiF4, SO2, F-2, SO2F2, SOF2, SOF4, S2F10, S2OF10, S2O2F10, and SF4 The results revealed that at 40 W, eta(SF6) exceeded 99%, and the reaction Products were almost all converted into stable compounds such as SiF4, SO2, and F-2 with or without the addition of oxygen. Sulfur oxyfluorides such as SO2F2, SOF2, SOF4, S2OF10, and S2O2F10 were produced only below 40 W The results of this work can be used to design a plasma/chemical system for online use in a series of a manufacturing process to treat SF6-containing exhaust gases.