Study of thin Film Formation From Silicon-Containing Precursors Produced by an RF Non-Thermal Plasma Jet at Atmospheric Pressure



The deposition of thin silicon-organic films by atmospheric pressure PECVD using an RF-excited plasma jet has been investigated experimentally and theoretically. Static deposition experiments have been performed on flat polymer and glass samples using the silicon containing molecules HMDSO, OMCTS and silane. The experiments are classified with respect to power, flow rate, operating conditions and deposition rate. The deposited films have been analysed using profilometry and Fourier transform infrared spectroscopy. It is found that electric power and gas flow stability determine distinctive areas in the operating diagram characterized by the deposition rate, profile shape and the chemical properties of the film depending on introduced precursors. The highest O/Si ratio (close to two) is found for laminar flow regimes. Here, the films are characterized by a low carbon content, too. The experimental findings for different flow conditions are discussed in relation to results of a two-dimensional axisymmetric fluid model. The model predicts the interaction of gas heating and flow, the plasma generation in the active volume, the transport of active plasma particles into the effluent and the generation and transport of precursor fragments towards the substrate surface. A remarkable influence of the gas flow on the plasma kinetics is observed only with respect to the density of molecular argon ions, which are transported together with electrons into the effluent. The calculated flux of precursor fragments onto the substrate surface agrees qualitatively with measured profiles of the film thickness (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)