Berlin 2001 – scientific programme

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P: Plasmaphysik

P 7: Dusty Plasmas, Diagnostics III

P 7.6: Talk

Thursday, April 5, 2001, 17:55–18:10, 2032

Spectroscopic studies of H₂-Ar microwave plasmas containing diborane — •Mariana Osiac, Lars Mechold, and Jürgen Röpcke — Institute of Low Temperature Plasma Physics (INP), Friedrich-Ludwig-Jahn-Straße 19, 17489 Greifswald, Germany

Boron-containing microwave plasmas are applied for anti-corrosion layers with a considerable high hardness. Processes in the plasma volume connected with the surface treatment are only poorly understood. The monitoring of transient or stable chemically active plasma species is the key for an improved understanding of the main chemical processes in the plasma. This contribution presents recent investigations in H₂-Ar microwave plasmas (f= 2.45 GHz) containing 3.2 % diborane using tunable diode laser absorption spectroscopy (TDLAS)[1] and emission spectroscopy. Absorptions of diborane and of the fragmentation molecule BH₃ as well as characteristic emission of BH, B and H atoms have been measured dependent on discharge power (1 - 2.4 kW) and pressure (1 - 2.5 mbar). The degree of dissociation of the diborane precursor was found to be in range of 70 to 90 % and the corresponding fragmentation rate of diborane was determined to about 10¹⁵ molecules/J.

Results were used to analyse main chemical pathways. Based on the measured behaviours an appropriate reaction scheme was established.

[1] J. Röpcke et al., Rev. Sci. Instrum. 71, 3706 (2000).