RF magnetron discharge model based on power balance

Abstract

Previously developed theoretical approach to model asymmetrical capacitively coupled RF discharge is applied in the case of RF magnetron discharge. The method is based on deriving theoretical dependence of the FR power dissipated in the discharge on the DC selfbias voltage. These are easily measurable quantities and this experimental data is fitted with the theoretical model. Latter is based on rather broad assumptions and is applicable in large variety of cases. Experiments with Ar and O2 at low pressure are conducted. The data obtained fits perfectly with the model. The dependence of the total ion current, bombarding the target on the discharge conditions (applied power) is derived. The results show that independently on the similarity in the initial data, a substantial difference in the plasma sustaining power in both cases can be distinguished. This fact can be attributed to the presence of a number of vibrational rotational levels in O2 molecules, absent in Ar. The additional power needed to sustain O2 plasma goes for excitation of the vibrational rotational levels.