Influence of the process parameters on the characteristics of silicon-incorporated a-C:H:SiOx coatings

• Characteristics of SiOx-incorporated carbon coatings is presented.
• The formation of SiOx precipitates depends on the applied process parameters.
• The mechanism of evolution of Raman spectra of a-C:H:SiOx layers is proposed.
• Roughness of SiOx-incorporated DLC can be controlled by the negative bias.

Silicon is considered as a unique, the most effective and interesting doping element that makes the diamond-like carbon coatings promising material for a variety of technical and medical applications. For CVD processes, the most popular silicon precursors are silane and tetramethylsilane (TMS) in combinations with methane, benzene or acetylene. Considerably less attention is paid to the other precursors of silicon, namely, these containing oxygen, particularly hexamethyldisiloxane (HMDSO). Despite few reports in this subject, so far there is a lack of the comprehensive presentation of the influence of the working gas mixture and process parameters on the overall properties of obtained layers. This work is related to in-depth analysis of the topography, morphology, chemical structure and composition of a-C:H:SiOx layers, produced using wide range of process parameters, that is based on the scanning electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. Results of the analysis show that the morphology, chemical structure and phase composition of synthesized layers depend on the applied negative bias potential and working atmosphere, wherein this correlation is not always straightforward.