Plasma diagnostics during thin films depositions

kniha odborná

angličtina

The thesis deals with the plasma diagnostics during the deposition of the polymer thin films based on organosilicons. We were focused on the characterisation of the deposition processes using hexamethyldisiloxane (HMDSO), vinyltriethoxysilane (VTEO) and tetravinylsilane (TVS) as monomers. Experiments were carried out dominantly in the RF inductively coupled discharge in the reactor which was constructed at the Institute of Material Science at Faculty of Chemistry, Brno University of Technology. The mass spectrometry, optical emission spectroscopy and gas chromatography with mass spectrometry were used for plasma diagnostics. The Fourier transform infrared spectroscopy (FTIR) was used for the thin film diagnostics. The results were completed with the others from ellipsometric and contact angle measurements. Moreover, elemental composition and chemical structure were studied by Rutherford backscattering spectroscopy (RBS) and with Elastic recoil detection analysis (ERDA). The work is focused mainly on the depositions which were carried out in a pulse mode. The pulse duration was changed from 1:1 to 1:999 (discharge on of 50 W was always 1 ms, discharge off was varied from 1 to 999 ms), and thus the effective power was changed from 25 to 0.5 W. The mass spectra and optical emission spectra were recorded during the depositions at various different effective powers for the all monomers. The oxygen addition was tried to obtain the optimum deposition conditions. It was found that oxygen plays an important role in plasma chemistry but its flow rate is not the most important parameter during the deposition. Various radiative particles (atomic, diatomic and some larger species) were identified in the optical spectra. Relative densities of the selected particles that were the most intensive in the spectra (it means in the gas phase) were plotted as a function of the effective power and/or oxygen or monomer flow rate. The elemental composition of the plasma polymer films was studied as a function of effective power, too. The results from the gas-phase diagnostics were confronted with the results obtained by thin layer diagnostics. Based on this comparison models of probable fragmentation and deposition mechanisms were suggested for each monomer. Finally, the probable plasma polymer structures were drawn out for all monomers. It was found that it is possible to accomplish the optimum conditions for the polymerisation of required thin films that can be used as interphase for the composite materials. It could be done mainly by changing the effective power and monomer flow rate. It was found that the most important parameter in our case is the effective power. With increasing effective power, the density of small particles such as H, O, H2, C2, CO, CH, etc... increase in the volume while in the layers the concentration of these particles decreases. Mainly the bonds such as Si-O-Si, Si-Si, Si-H are created in the layer. Furthermore, it was found the range of effective power where the significant changes occur in the spectra character as well as in the layer properties. This effective power range and the deposition conditions improvement are the objective of further studies. Simultaneously, the research will be carried out also in the field of the kinetics of monomer fragmentation and consequent polymerisation as well as of the created polymer structures. The results obtained during the depositions using TVS are presented in this paper.

Plasma deposition, plasma kinetics, organosilicones, optical emission spectroscopy, thin layers, mass spectrometry, actinometry, GC-MS spectroscopy

RAŠKOVÁ, Z.

2006

1. 8. 2006

VUTIUM

Brno

80-214-3233-0

Plasma diagnostics during thin films depositions

PhD Thesis

387

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