F-atom kinetics in SF6/Ar inductively coupled plasmas

The F-atom kinetics in SF6 and SF6/Ar inductively coupled plasmas ( ICPs) were investigated using a global model. This report particularly focuses on the effects of ICP power and Ar fraction on F-atom density and its main production and loss mechanisms. The results are presented for a relatively wide pressure range of 1-100 mTorr. Very different behaviors were observed for Ar fractions in the low- and high-pressure limits, which can be attributed to different electron kinetics. In addition, the authors found that increasing the Ar fraction in the SF6/Ar plasma has almost the same effects on the F-atom kinetics as increasing the power in the SF6 plasma. This is because a high electron density occurs in both cases. Moreover, it was confirmed that, for both sample types, a cycle of F atoms formed in the bulk plasma. The source of these is F-2 molecules that are first formed on the chamber wall and then emitted. Finally, the simulations of F-atom kinetics are validated by quantitatively comparing the calculated electron and F-atom densities with identical experimental discharge conditions. (C) 2016 American Vacuum Society.