Stuttgart 2012 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 18: Theorie/Modellierung
P 18.4: Vortrag
Donnerstag, 15. März 2012, 15:15–15:30, V57.01
Hydrodynamic modelling of oxygen rf discharge — •Igor Sheykin, Markus M. Becker, and Detlef Loffhagen — INP Greifswald, Felix-Hausdorff-Str. 2, 17489 Greifswald
Capacitively coupled RF (CCRF) oxygen plasmas are widely used for e.g. etching and sputtering. For a detailed understanding of the plasma behaviour, the influence of negative ions is of interest because of their effect on the charged species transport, plasma sheath conditions and the production of electrons due to detachment processes. In addition, metastable molecules can become important as well because of their large particle densities expected. To describe the spatiotemporal behaviour of CCRF oxygen plasmas in a discharge between plane electrodes with a gap of 2.5 cm, a hydrodynamic model has been used. It consists of the solution of the coupled system of the Poisson equation, of balance equations for the densities of 17 heavy particle species and the electrons as well as of the electron energy density involving about 180 collision processes in the reactive scheme. Assuming radial symmetry of the discharge plasma, a time-dependent, spatially one-dimensional model has been employed. The analysis has been performed for the periodic state at pressures between 50 and 1000 Pa, voltages from 0.2 to 1 kV and a frequency of 13.56 MHz. In particular, it was found that the densities of metastable molecules and atomic oxygen reach about 1% of the background gas density. O− is the predominant negative ion in the plasma bulk, while the density of O2− and of electrons is at best one half of the O− density in the plasma bulk.
The work was supported by DFG within SFB-TRR 24.