Deposition of Carbonaceous Siloxane Films via Atmospheric Pressure PECVD

Transparent SiO₂ coatings have been used in applications ranging from microelectronics, optical applications, antireflection coatings, and as barrier layers or hard coatings on polymer substrates.  In this study, the investigators explore a newly developed afterglow type atmospheric plasma system that enables the treatment of conductive surfaces and the co-deposition of metallic nano-particulates in the AP-PECVD film. Organosiloxane precursors (HMDSO and TMCTS) are mixed with Au nano-rods and AP-PECVD coatings are attempted on both silicon wafers and ultra-high molecular weight polyethylene (UHMWPE). It was desirable to gain an understanding of what effects AP-PECVD parameters (substrate material, precursor type and plasma power) had on the properties of the resulting SiO₂ film.  Additionally, three precursor delivery methods (bubbler, nebulizer, and aerosol) were used in order to co-deposit nanoparticles within the SiO₂ coating. Scanning electron microscopy (SEM), X-Ray photoelectron spectroscopy (XPS), and Rutherford backscattering spectroscopy (RBS) were used to characterize the coatings. From analysis it was determined that the carbon content within the SiO₂ is greatly dependent on the plasma power and precursor flow rate, allowing the deposition of gradient coatings that vary from polymeric (~18% C) to wear-resistant (~4% C). SiO₂ nanoparticles were successfully co-deposited with the SiO₂ films.