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 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⁺, Ar_m, and Ar^*. In CF₄, the electron impacts with CF₄ are the main paths to produce , , CF⁺, F⁺, , CF₂, F₂, , F⁻, CF₃, and F. Besides,  →    +  F and  +  F  →  CF₃  +  F⁻ produce part of and F⁻. Decomposition, recombination, and charge exchange reactions all contribute to the generation of CF₃ and F. In the Ar/CF₄ mixture, Ar  +    →  CF₃  +  Ar⁺ and CF₄  +  Ar⁺  →    +  F  +  Ar produce a great deal of Ar⁺, , 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. (paper)