Silicon nitride films, deposited onto flexible polyethersulfone substrates by plasma-enhanced chemical vapor deposition, were investigated for water vapor transmission rate and O transmission rate barrier applications. Details of the NH3/SiH4 flow ratio and chamber pressure effects on the SiNx/polyethersulfone properties in terms of chemical bonding, transmittance, refractive index, deposition rate, adhesion, roughness, O transmission rate and water vapor transmission rate were investigated. When the NH3/SiH4 flow ratio increased from 1.43 to 10, evident variations in refractive index and transmittance of the SiNx/polyethersulfone samples were observed. Moreover, as the chamber pressure increased from 26.7 to 133.4Pa, the deposition rate, adhesion and roughness increase while no evident variations in water vapor transmission rate and O transmission rate were observed. Under optimum conditions, the water vapor transmission rate and O transmission rate of 100nm-thick SiNx barrier coating on polyethersulfone at 150C decreased to a value of near 0.01g/m2/day and 0.01 cm3/m2/day, respectively.

Water and Oxygen Permeation of Silicon Nitride Films Prepared by Plasma-Enhanced Chemical Vapor Deposition. D.S.Wuu, W.C.Lo, C.C.Chiang, H.B.Lin, L.S.Chang, R.H.Horng, C.L.Huang, Y.J.Gao: Surface and Coatings Technology, 2005, 198[1-3], 114-7