Comparative analysis of film formation in glow-discharge plasma in mixtures of methane with neon and argon

Concentrations of Ne, Ar, and H atoms in metastable and resonance states, concentrations of atomic hydrogen, and the growth rates of polymer films were determined in the dc glow discharge in the Ne and Ar mixtures with (1–5) % CH₄ in the pressure range of 13–520 Pa and discharge currents of 5–100 mA. The method of ellipsometry was used to control the refraction index and thickness and the composition of polymer films was analyzed with the help of the IR spectroscopy method. Mathematical simulation of discharges under the given conditions was performed. The calculation results were compared to the experimental data. It is shown that the mechanism of the ionization and dissociation processes in discharges with mixtures containing Ne differ considerably from the mechanism of these processes in discharges in mixtures with Ar, which significantly affects the film formation processes. Prolonged tests under ambient conditions showed the high stability of most of the films grown under the discharge in the mixtures of Ar and CH₄ (the film refraction index in the case of conditioning up to 10 years decreased by about 0.1 within the measurement error) and in mixtures of Ne with CH₄ (the film refraction index under prolonged conditioning features remains almost unchanged).