Global model of inductively coupled radio-frequency Cl<inf>2</inf> plasma: Dissociation, excitation and power modulation

Abstract

Summary form only given. Plasmas are commonly used for industrial surface processing. Reactive molecular gases are used which have complex chemical kinetics. For example, Cl2 is widely used for plasma etching processes. The electronegative nature of this molecular gas makes the investigation harder, compared to electropositive atomic plasmas. Dissociation of Cl2 by electronic collisions is substantial, in addition to the ionization processes. Negative and molecular positive ions are produced. Additionally, atomic and molecular excited levels play an active role. We have modelled an inductively coupled radio-frequency Cl2 plasma via a global model. The plasma is formed in a cylindrical column with a pressure range of 2-50 mTorr and power input 100-500 W, and includes gas-phase and surface reactions. Although a steady state global model of Cl2 has been presented, a detailed study of excited state atoms and molecules, as well as the effect of power modulation has not been made. Compared to Thorsteinsson et. al., we have added spin-orbit excited Cl(P1/2) and use an updated set of rate coefficients for electronic and vibrationally excited Cl2. The steady-state particle densities and electron temperature are calculated as a function of power input and the pressure, and compared to experimental results, giving reasonable agreement. In the future we plan to extend the model to time-resolved densities in pulse-modulated plasmas.