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P: Fachverband Plasmaphysik

P 16: Poster

P 16.2: Poster

Wednesday, March 21, 2007, 16:30–18:30, Poster A

Measurements of the negative ion concentration in argon-oxygen discharges using phtodetachment. — •Nadiya Sydorenko^{1, 2}, Olaf Grulke^{1, 2}, Albrecht Stark^{1, 2}, and Thomas Klinger^{1, 2} — ¹MPI für Plasmaphysik, EURATOM Assoziation, Greifswald — ²Ernst-Moritz-Arndt Universität, Greifswald

The formation of negative ions has attracted attention in plasma processing application like e.g. semiconductor fabrication, where negative ions can considerably effect in the etching quality [1]. High density (n 10¹⁷ m⁻³ ) argon and oxygen plasmas are generated during helicon discharge in the experiment VINETA. Measurements of the negative oxygen ion concentration for different discharge scenarios will be presented. The relative concentration of negative ions is measured by Langmuir probe techniques and by laser-induced photodetachment [2] combined with microwave interferometry. Special attention is paid to the dependence of the negative ion concentration on the gas pressure, argon admixture, and RF power. By radially scanning the laser used for phtodetachment also the radial profile of the negative ion concentration is resolved and will be compared to the radial plasma profiles. [1] S.Samukawa, Appl. Phys. Lett. 68 (1996). [2] M. Shibata et al., J. Phys.D: Appl. Phys. 30 (1997).