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P: Plasmaphysik
P 9: Dense Plasmas and Plasma Diagnostic (Poster Session)
P 9.18: Poster
Tuesday, April 3, 2001, 12:30–15:00, AT2
Spectroscopic diagnostics of a DBD in Ar/CxFx mixtures — •I.P. Vinogradov, A. Dinkelmann, and A. Lunk — Institut für Plasmaforschung, Universität Stuttgart, Pfaffenwaldring 31, 70567 Stuttgart, Germany
In this work plasmapolymerisation processes in a dielectric barrier discharges (DBD) at a pressure of one bar have been studied. FTIR and UV absorption and UV - VIS emission spectroscopy was applied to get information on the absolute density of CF2 and the reaction products in a DBD running in Ar/fluorocarbon mixtures. The following fluorocarbon molecules have been studied: CF4, C2F6, C2H2F4, C3HF7, C3F8, and c-C4F8. From IR absorption spectra of the DBD in the mixture of fluorocarbon with Ar almost all stable products were identified. In mixtures of Ar/CF4 and Ar/C2F6 the very bright yellow emission in the region 450-750 nm which belongs to the CF3-radicals was observed. We found that the CF3-emission bands occur strongly in the case if CF4 and C2F6 are used as precursor gases to a basic argon filling. This emission is factor of more than 100 smaller in the case of C2H2F4 and c-C4F8. The emission of CF2-lines in the range of 200 - 360 nm show highest intensity in the case of c-C4F8. The highest absolute CF2-densities was also detected for c-C4F8 molecules by using integrated UV absorption spectroscopy.
We found that polymer films can be deposited if the ratio F/C is higher or close to 2, well known for low pressure discharges. FTIR absorption spectroscopy of the films on Si wafer indicates that the main absorption belongs to CF2-groups (1220 cm−1). In addition, absorption peaks which belong to No-dqamorphousNo-dq PTFE (at 723-741 cm−1), CF3-groups (980 - 986 cm−1 and 1285 cm−1) and CF-groups (1090 cm−1 and 1340 cm−1) are also observed in the spectra.