| AVS 58th Annual International Symposium and Exhibition | |
| Plasma Science and Technology Division | Wednesday Sessions |
| Session PS+SE-WeM |
| Session: | Atmospheric Plasma Processing and Micro Plasmas |
| Presenter: | Jan Benedikt, Ruhr-University Bochum, Germany |
| Authors: | J. Benedikt, Ruhr-University Bochum, Germany R. Reuter, Ruhr-University Bochum, Germany D. Ellerweg, Ruhr-University Bochum, Germany K. Ruegner, Ruhr-University Bochum, Germany T. de los Arcos, Ruhr-University Bochum, Germany A. von Keudell, Ruhr-University Bochum, Germany |
| Correspondent: | Click to Email |
Deposition of thin films with plasmas at atmospheric pressure is always a challenging task because of high collision rates, absence of ion bombardment, filamentary behavior of the plasma and limited knowledge of plasma chemistry. The preparation of high quality thin films is therefore still the main domain of low pressure plasmas. One of films, which can be prepared at atmospheric pressure, is SiO2. Hexamethyldisiloxane (HMDSO) and O2 (or N2O) are usually used as precursors fed into the plasma.
We have shown in the past that a good quality SiO2 films can be prepared by means of microplasma jets driven by RF voltage and operated in Ar or He as plasma forming gas. Here we concentrate on the study of plasma chemistry and surface reactions leading to the film growth. The geometry of the microplasma jet and the localization of the plasma treatment allow studying of gas phase reactions and plasma-surface interaction separately. Molecular beam mass-spectrometry is used to measure HMDSO depletion and stable products in the gas phase. Depletion below 15% and limited fragmentation is observed even under conditions with high O2 density, which leads to formation of carbon free SiO2 films. The plasma-surface interaction is studied by application of several jets with different gas mixtures (He/HMDSO, He/O2, He/H2...) to the same trace on the rotating substrate in controlled helium atmosphere. It is shown that surface reactions are responsible for the carbon removal from the grown film. Infrared spectroscopy, spectroscopic ellipsometry and X-ray photoelectron spectroscopy measurements are performed to analyze film properties and compare them with plasma measurements. A fluid model of gas flow and reaction kinetics in the effluent of the plasma is used to reproduce observed trends and measured deposition rates. Good agreement is achieved with relatively simple model of plasma chemistry and surface reactions.