Growth Manner of Silica Film on Polyethylene Terephthalate Substrates in Plasma-Enhanced Chemical Vapor Deposition

Abstract

Silica films have been synthesized on a polymeric substrate, that is, polyethylene terephthalate (PET), by low-temperature plasma-enhanced chemical vapor deposition using an organosilicon compound and oxygen. Scanning electron microscope images clearly showed that the silica growth process depended on deposition conditions, including substrate surface conditions and the presence of activated oxygen species. Fragments of the organosilicon compound molecules are thought to adsorb selectively on energetically advantageous areas of the PET substrate. Dome-shaped silica structures formed in this manner on the polymeric surface in the early stage of the deposition. When no active oxygen species existed in the plasma, the boundaries between these domes remained in the deposited film even when the deposition was further prolonged. On the other hand, in the presence of activated oxygen species in the plasma, these silica domes fused to each other and, consequently, a fairly smooth film was formed at an increased deposition time. Finally, densely-packed silica films were successfully formed on the PET substrates.