Effects of CF4 content on particle densities and reaction pathways in atmospheric-pressure Ar/CF4 pulsed dielectric barrier discharge plasma

Ar/CF4 discharge plasma etching is a promising approach to achieving a high etch rate and anisotropic etching. A 1D fluid model is established to numerically study the effects of CF4 content on particle densities and reaction pathways in Ar/CF4 pulsed dielectric barrier discharge plasma at atmospheric pressure. The simulation results indicate that, with increasing CF4 content, Ar+ densities decrease but the densities of other positive ions increase, and the electron densities do not undergo a dramatic change but the CF3- densities present an approximately linear increase. The densities of CF3 and F reach their maximums when the CF4 content is 70%. In Ar, the electron impacts with Ar are the essential reaction pathways to generate Ar+, Arm, and Ar*. In CF4, the electron impacts with CF4 are the main paths to produce CF4+, CF2+, CF+, F+, CF3-, CF2, F-2, CF3+, F-, CF3, and F. Besides, CF4+ -> CF3+ + F and CF3- + F -> CF3 (+) Fproduce part of CF+ 3 and F-. Decomposition, recombination, and charge exchange reactions all contribute to the generation of CF3 and F. In the Ar/CF4 mixture, Ar (+) CF3+ -> CF3 (+) Ar+ and CF4 (+) Ar+ -> CF3+ + F (+) Ar produce a great deal of Ar+, CF3+, CF3, and F. The contribution ratios of the reactions CF4 (+) e -> CF3 (+) F+ + 2e and F+ + CF+ -> F + CF continuously increase with increasing CF4 content.