Effects of ROS and RNS in non-equilibrium plasma enhanced oxidizing and nitriding

Plasma enhanced oxidizing and nitriding processes are of great interest for physics and applications [1]. However, despite all advances in plasma technology, mechanisms of non-equilibrium plasma chemistry are not quite clear, particularly concerning reactive oxygen and nitrogen species (ROS/RNS) in metastable states. We tried to study this matter more detail. Experiments were done in a low temperature magnetron with a non-self-sustained glow discharge in oxygen/nitrogen/argon mixtures, employing electrical and optical diagnostics. Measurements showed that plasma processing is accompanied by the formation of electronically excited particles ROS/RNS. Computer modeling by using 0D-kinetic and 1D-fluid models including ionization, excitation, dissociation-recombination, vibrational relaxation, collisional quenching and radiation revealed the most probable mechanisms of plasma-chemical transformations. Effects of metastables of singlet oxygen O$_{\mathrm{2}}^{\mathrm{\ast }}$(a,b) and nitrogen N$_{\mathrm{2}}^{\mathrm{\ast }}$(A) as well as small but important radicals O$^{\mathrm{\ast }}(^{\mathrm{1}}$D), N$^{\mathrm{\ast }}(^{\mathrm{2}}$D) were also examined. Our study confirms the role of ROS/RNS in plasma kinetics and indicates the way toward more efficient oxygen and nitrogen plasma processing. [1] M.A. Lieberman, A.J. Lichtenberg, Principles of Plasma Discharges and Materials Processing, John Wiley {\&} Sons, 2005.