One-Dimensional Numerical Simulation of a Capacitively Coupled Oxygen Plasma Driven by a Dual Frequency Generator at Low Temperature

Abstract

The Single and double frequency non-equilibrium capacitively coupled (CCP) radiofrequency plasma sources are commonly used in the laboratory for research and for a variety of processing and techniques. This study is carried out on the basis of a one-dimensional, self-consistent fluid model and corresponding governing equation are described in details in the present report. Our simulation results show that the ozone (${\text{O}}_{3}$) is efficiently generated in the bulk of the discharge in case of helium-oxygen admixture as compared to our recent work [1] carried out on pure oxygen. They also show that the formation of the metastable singlet molecule (${\text{O}}_{2} \left( {{\text{a}}^{1} \Delta_{\text{g}} } \right)$) and the atomic oxygen (${\text{O}}$) are important as compared with pure oxygen plasma and which has a significant influence on the electron heating process. This is due to high rate of production of these species and low rate of destruction and recombination. The rate of production of negative oxygen (${\text{O}}^{ - }$) and positive (${\text{O}}_{2}^{ + }$) molecular ions are also important but less than the neutral atoms and molecules. The formation of positive (${\text{He}}^{ + }$), (${\text{He}}_{2}^{ + }$) and (${\text{O}}^{ + }$) ions are almost of the same order of magnitude which is about 10⁻² less than the (${\text{O}}^{ - }$) and (${\text{O}}_{2}^{ + }$) ions. This can be explained by the fact that the electron-impact ionization of oxygen molecules can dominate over helium ionization due to the lower ionization threshold of the oxygen molecule (12.6 eV for ${\text{O}}_{2}$ vs. 24.6 eV for He).