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P: Fachverband Plasmaphysik

P 7: Poster

P 7.1: Poster

Montag, 19. März 2007, 16:30–18:30, Poster A

Temporal and spatial distributions of radicals in pulsed fluorocarbon discharges - a DoE study — Jakob Barz^1,2, Michael Haupt¹, Christian Oehr¹, and •Achim Lunk² — ¹Fraunhofer IGB, Nobelstr. 12, 70569 Stuttgart — ²Institut für Plasmaforschung, Universität Stuttgart, Pfaffenwaldring 31, 70569 Stuttgart

A Design of Experiments (DoE) study was carried out, comparing spatial radical densities in several pulsed fluorocarbon discharges depending on time.

Laser-induced fluorescence (LIF) was applied to study reaction mechanisms in the plasma in dependence on gas flow, pressure and electric power as well as on pulse parameters. The species investigated were CF (lifetime 25 ns) and CF₂ (lifetime 55 ns). Experiments were performed mainly in CHF₃-plasmas, diluted with argon.

It turned out that the CF density is strongly influenced by the mean power applied and increases by half an order of magnitude by increasing the power from 20 to 80 W at pressures between 0.3 and 0.8 mbar. In contrast to this result, CF₂ densities are hardly influenced by the power variation. On the other hand, CF densities are hardly influenced by variation of the pressure, contrary to the influence on CF₂ densities.

Beside the spatial distribution of particle densities, the time-resolved development of the observed species after plasma ignition and at several stages of the pulse period will be also shown in detail.