Ion beam assisted chemical vapor deposition of hybrid coatings : process diagnostics and mechanisms

In the present work, we investigate the fundamental gas-phase processes during the application of the ion beam assisted chemical vapor deposition method for the synthesis of hybrid (organic-inorganic) optical coatings. The liquid monomer Hexamethyldisiloxane was used as a model precursor for the fabrication of low index optical films. Comprehensive diagnostic analysis has been performed by employing a combination of mass spectrometry, optical emission spectroscopy, and Langmuir probe measurements. Assessment of the correlation between the process parameters and the film growth indicated a crucial role of the ratio between the ion beam power density and the precursor flow rate in controlling the monomer fragmentation rate. Controlling these two principal process variables is proposed as an effective tool for tuning the deposition rate and the density and optical properties of the growing films.