An analytical model of multi-component radio frequency capacitively coupled plasma and experimental validation

Abstract

An analytical model describing the hydrogen added argon radio frequency capacitively coupled plasma is presented and its predictions are tested with the experimental results. In the analytical model, it is found that the rf current density, electron temperature and density, as well as the density of light ion in multi-component plasma collectively influence the normalized sheath thickness and potential. As for low pressure rf plasma, the sheath potential is the qualitative measure of the DC self bias, the change of DC self bias with hydrogen addition is predicted in this model. The values of electron density and temperature as a function of hydrogen content in the discharge is calculated on the basis of a homogeneous discharge model using the rms values of current and voltage as well as by rf compensated Langmuir probe at different experimental conditions. In the experiment with hydrogen added argon plasma, the rf power as well as the working pressures are varied. The presence of hydrogen in the argon discharge leads to the decrease of electron density and increase of electron temperature. The measured DC self bias for the hydrogen added argon plasma is found lower than the pristine argon plasma. This decrease of DC self bias with hydrogen addition is in accordance with predictions of the theoretical model.