The direct current (dc) glow discharge plasma parameters and active species kinetics in HCl-X (X = Ar, N2, H2, Cl2, O2) mixtures were studied using both plasma diagnostics Langmuir probes and modeling. The 0-dimensional self-consistent steady-state model included the simultaneous solution of Boltzmann kinetic equation, the equations of chemical kinetics for neutral and charge particles, plasma conductivity equation and the quasi-neutrality conditions for volume densities of charged particles as well as for their fluxes to the reactor walls. The data on the steady-state electron energy distribution function, electron gas characteristics (mean energy, drift rate and transport coefficients), volume-averaged densities of plasma active species and their fluxed to the reactor walls were obtained as functions of gas mixing ratios and gas pressure at fixed discharge current.
In this work, the investigations of plasma parameters and active particles kinetics in an HCl dc glow discharge were carried out using the combination of plasma diagnostics and plasma modeling. The modeling was based on the self-consistent solution of Boltzmann kinetic equation and the balance equation of chemical kinetic for neutral and charged particles. It was shown that the electron impact dissociation of HCl is the main source of both Cl and H atoms while the total balances for all kinds of neutral particles are noticeably influenced by the volume atom-molecular reactions. The population of the vibrational energy levels for HCl molecules was found to be low, but the role of the HClv>0 in the negative ions formation process cannot be neglected. The assumption of the first-order heterogeneous recombination kinetics for both Cl and H species provides a good agreement between the modeling and plasma diagnostics data.
In this work, we investigated both etching characteristics and mechanisms of Au thin films using Cl2/Ar gas mixture in an inductively coupled plasma (ICP) system. For these purposes, a combination of experimental methods and modeling was used. It was found that an increase in Ar mixing ratio under constant operating conditions causes non-monotonic behavior of Au etch rate, which reaches a maximum 80% Ar. A study of surface composition using X-ray photoelectron spectroscopy (XPS) showed that the etching in chlorine-rich plasma is escorted by accumulation of AuClx on the etched surfaces. Langmuir probe measurements indicated a noticeable sensitivity of both electron temperature and electron density to the change of Ar mixing ratio while 0-dimensional model of volume kinetics showed monotonic change of both densities and fluxes of active species such as chlorine atoms and positive ions. However, analyses of surface kinetics showed that the non-monotonic etch rate behavior may be produced by the concurrence of physical and chemical pathways in ion-assisted chemical reaction.
Plasma parameters and chemical kinetics of Cl2/Ar plasma were investigated aimed at understanding the mechanism of Ar addition on mass composition of charged and neutral particles. The analysis was based on both experimental methods and plasma modeling. It was found that addition of Ar to Cl2 leads to deformation of the electron energy distribution function and to increase of the electron mean energy. Direct electron impact dissociation of Cl2 molecules represents the main source of chlorine atoms in plasma volume. The contributions of stepwise dissociation and ionization involving Ar metastable atoms were found to be negligible. Addition of Ar to Cl2 causes the decrease of both electron and ion densities due to the decrease of the total ionization rate and the acceleration of heterogeneous decay of charged particles.