PLASMA PARAMETERS AND FLUORINE ATOM DENSITY IN SF6 + Ar + He GAS MIXTURE: EFFECTS OF Ar/He MIXING RATIO, PRESSURE AND INPUT POWER

The influence of the initial mixture composition, gas pressure and input power on electro-physical parameters and density of fluorine atoms in SF6 + Ar + He plasma produced in an inductive-type reactor at 2 MHz was investigated. The combination of plasma diagnostics by Langmuir probes and optical emission spectroscopy allowed one to determine behaviors of electrons- and ions-related plasma characteristics vs. variable operating parameters as well as to suggest mechanisms responsible for corresponding effects. In particular, it was shown that the substitution of argon by helium at constant SF6 content in a feed gas affects the electron temperature, densities of charged species and plasma electronegativity through changes in both total ionization rate and electron energy losses during their interactions with dominant neutral particles. It was found that input power produces the maximum effect on the F atom density (by ~ 9 times at w = 800–1250 W) while the influence of the Ar/He ratio and gas pressure (especially at p < 15 mtorr) appears to be much weaker. Such situation is caused by opposite trends of electron temperature and electron density that results in rather small changes in the effective frequency of SFx + e → SFx-1 + F + e reaction family. It was found that fluxes of both fluorine atoms (ГF) and positive ions (Г+) follow changes in their densities, and the minimum ГF/Г+ value in He-rich plasmas corresponds to low pressures and input powers. For citation: Miakonkikh A.V., Kuzmenko V.O., Efremov A.M., Rudenko K.V. Plasma parameters and fluorine atom density in SF6 + Ar + He gas mixture: effects of Ar/He mixing ratio, pressure and input power. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2025. V. 68. N 3. P. 42-49. DOI: 10.6060/ivkkt.20256803.7130.