Organosilicon/silicon oxide gas barrier structure encapsulated flexible plastic substrate by using plasma-enhanced chemical vapor deposition

An organosilicon/silicon oxide (SiOx) multilayered barrier structure was consecutively deposited onto the polyethylene terephthalate (PET) substrate by plasma-enhanced chemical vapor deposition (PECVD) using tetramethylsilane (TMS) monomer and TMS–oxygen gas mixture, respectively. The thickness of the SiOx film directly deposited onto the PET substrate was firstly designed to perform the best barrier property to water vapor permeation, which also possessed the optimal surface uniformity and SiOSi structural order. By insetting an adequate thickness of the organosilicon layer plasma-polymerized from TMS monomer between the SiOx film and PET substrate, the water vapor transmission rate (WVTR) was further improved. The residual internal stress of such organosilicon/SiOx barrier structure was significantly lower than that of a single SiOx film deposited directly on the substrate. The improvement on the structural quality and surface densification of the organosilicon/SiOx barrier structures was discussed and observed from their chemical bond configurations and surface morphologies. Accordingly, low water vapor permeation below the MOCON detection limit (< 1 × 10− 2 g/m2/day) was achievable from the PET substrate coated with the 6-pairs of the organosilicon/SiOx multilayered barrier structure by PECVD using the same monomer precursor.