Characterization of Plasma-deposited a-C:H:Si:F:N Films

• Published in: Materials research (São Carlos, São Paulo, Brazil) São Paulo, Brazil), 2021-01, Vol.24 (suppl 1), p.1
• Main Authors: Lopes, Juliana Feletto Silveira Costa, de Oliveira Furquim, Felipe, Rangel, Elidiane Cipriano, Durrant, Steven F.
• Format: Article
• Language: English
• Subjects: a-C:H:Si:F:N; Contact angle; Diameters; Energy dissipation; ENGINEERING, CHEMICAL; Fluorination; Fourier transforms; Infrared spectroscopy; MATERIALS SCIENCE, MULTIDISCIPLINARY; METALLURGY & METALLURGICAL ENGINEERING; Near infrared radiation; optical properties; Partial pressure; PECVD; Silicon; Spectrum analysis; Thin films; Vapor phases; Water drops
• ISSN: 1516-1439; 1980-5373; 1980-5373
• DOI: 10.1590/1980-5373-mr-2021-0016

Thin a-C:H:Si:F:N films were studied as a function of the partial pressure of SF6 in plasma feed, RSF, together with tetramethylsilane and N2. Deposition rates varied from ~4 to ~19 nm.min-1. Surface roughnesses were typically less than 35 nm. Surface contact angles with water droplets, measured using goniometry, were all around 90°. Scanning electron micrography revealed surface particles, probably formed in the gas phase, of typical diameters ~8 μm. As revealed by Fourier transform infrared spectroscopy and energy dispersive x-ray spectroscopy, the films are plasma polymers with a carbon and silicon network. Most of the films contain ~ 60 at.% C, ~ 10 at.% Si, 20 at.% O and ~5 to 14 at.% N. Film doping with F rises to ~2 at.% as RSF is increased. The Tauc gap, calculated from ultraviolet-visible near infrared spectroscopic data, is controllable in the range of ~3.5 to 4.1 eV by a suitable choice of RSF. Fluorination causes the films to be softer and less stiff. Total deformation and stored energies are reduced compared to those of the film deposited at RSF = 0%. The modulus of dissipation increases from ~8% to a maximum of ~65% for the fluorinated films.