Reactive pulse magnetron sputtered SiOxNy coatings on polymers

Amorphous SiO2, Si3N4 and SiOxNy single layers have been deposited on silicon, glass and glycol modified polyethylene terephthalate substrates by reactive pulse magnetron sputtering. Apart from the expected correlation between refractive index, coating density and nitrogen content in the reactive gas mixture further results have been found regarding mechanical stress and the humidity barrier property of these thin films. The lowest compressive stress was observed in the coatings deposited with nitrogen contents of around 30% to 50% in the reactive gas mixture. The humidity barrier effect of the thin films already begins to increase significantly at low nitrogen contents of below 20% in the reactive gas. Additional investigations regarding chemical composition, coating adhesion and environmental stability complement this work with the main focus on optimizing these materials for optical multilayer systems on polymer substrates.