Characteristics of Silicon Oxynitride Barrier Films Grown on Poly(ethylene naphthalate) by Ion-Beam-Assisted Deposition

For the application of transparent barriers to water vapor permeation for plastic substrates, we have prepared silicon oxynitride thin films on a poly(ethylene naphthalate) substrate at room temperature by the ion-beam-assisted electron beam evaporation method and investigated their characteristics with respect to N-2 flow rate in the ion source. The experimental results reveal that when N-2 flow rate increases, the nitrogen concentration and Si-N bonding in SiOxNy films increase owing to the assisted N-2 ion incorporations during the film deposition process. Also, with increasing N-2 flow rate, the surface roughness and optical transmittance of the barrier film decrease, whereas refractive index and film density increase. It is confirmed that the water vapor transmission rate of our barrier films decreases with the incorporation of N-2 ions into the films, being strongly dependent on surface roughness and film density. (C) 2010 The Japan Society of Applied Physics