Decay Processes of Electrons in the Afterglow of High-Density CF₄, c-C₄F₈ and CF₄–H₂ Plasmas

Abstract

In this paper, a microscopic approach for the calculation of partial and total power dissipation from energy losses by collisions is considered and applied in the case of N 2 O low pressure RF discharges. This approach is based on a Monte Carlo technique in a particle model permitting sampling of the energy deposited by different inelastic electron-N 2 O collisions. The calculated power densities presented in this paper are in good agreement with the experimental results and those obtained by the classical macroscopic formula based on spatio-temporal integration of the product of current density and electrical field. This microscopic approach presents, however, a major advantage in comparison with the classical method (which only offers the possibility to calculate the global power dissipation) by making possible the calculation of all the power density terms, thereby permitting one to examine the relative contribution of each collision process in the power dissipation. Its application to N 2 O electronegative discharges, at 503 K gas temperature, several RF voltages and two different gas pressures shows how the power is dissipated through electron-gas processes. The power density variation is found to be proportional to the electron density variation brought about by the changes in attachment (i.e. e + N 2 O → N 2 + O − ), detachment (i.e. NO − + N 2 O → NO + N 2 O + e) and ionization (i.e. e + N 2 O → N 2 O + + 2e) processes. The role of each of these processes is fully studied with our particle model in order to explain the dissipated power variation.