Permeation barrier properties of silicon oxide films deposited on polyethylene terephthalate (PET) substrate using roll-to-roll reactive magnetron sputtering system

Abstract

Silicon oxide (SiOx) barrier films were deposited on polyethylene terephthalate (PET) substrate at 20°C using reactive dual magnetron sputtering system. The oxygen flow rate, input sputtering power and film thickness were changed to optimize the barrier properties of SiOx films. Details of sputtering power and film thickness effects on the SiOx properties in terms of residual stress, surface, roughness, density, interface of SiOx/PET, and water vapor transmission rate (WVTR) were investigated. Especially, we focused our attention on the effects of sputtering power on the final barrier properties. A high density of 2.42g/cm3 SiOx film with high transmittance of 92% was obtained. Even at low substrate temperature of 20°C, the 300nm-thick SiOx barrier film exhibited superior WVTR value of 7.7×10−3g/m2/day as a single barrier layer using roll to roll reactive sputtering. These experimental observations showed that the encapsulation barrier properties of SiOx films were significantly enhanced due to the change of effect of ion bombardment, which affected film density, surface roughness, and the interface of SiOx/PET.