Spatial Distributions of 3p54s States of Argon Atoms in RF Magnetron Sputtering Plasma with a Collisional-Radiative Model.

Thin films are used in various industrial fields, namely in the manufacture of solar cells, flat screens and in improving the physical properties of material surfaces. In thin film deposition processes, the degree of equilibrium and other plasma characteristics such as the nature, density and temperature must be identified in order to understand the occurrence of various phenomena. In this work, the main focus is on studying the spatial distributions of densities of excited states of Ar* (3p⁵4s (1s_x: x = 2-5)), as well as the relative contributions of processes such as the electron impact effect, the radiative de-excitation, the diffusion phenomena of metastable states and the Penning ionization in the population and depopulation of different argon atoms states. For this purpose, a Collisional-Radiative Model (CRM) including 41 states was applied using specified parameters in RF magnetron sputtering plasma. These parameters include electron temperature, electron and ion densities of argon. The rate equations of the state densities led to a matrix system that was solved numerically by iterative Gauss-Seidel Method. The results show that the axial distributions of different excited states and those on the cathode side are slightly larger than those found on the anode side, and they show also that both densities are less than at the reactor center. For metastable states 3p⁵4s (1s₅, 1s₃), the Penning ionization is important, but it is not important for resonant states 3p⁵4s (1s4, 1s₂). Different densities of the excited states are not symmetrical with respect to the center of the reactor due to the existence of a magnetic field at the cathode. [ABSTRACT FROM AUTHOR]