Content area
Full Text
Abstract
This chapter is a review of the status of gas diffusion barrier film synthesis on polymers by atmospheric pressure plasma enhanced chemical vapour deposition (AP PECVD). Nowadays the atmospheric pressure plasma is more and more recognized as an attractive and versatile tool in thin film technology, capable of both surface modification and synthesis of thin functional layers. In comparison to the well-established vacuum technology, atmospheric pressure plasma processing of materials has considerable advantages but also imposes serious challenges. The synthesis of gas diffusion barrier layers with a high density and free of defects on a polymeric substrates can be considered as one of the grand challenges in thin film deposition. Nevertheless, over the past 10 years a remarkable progress was achieved, primarily related to the development of the high current diffuse dielectric barrier discharge as a plasma source. This review will attempt to summarize the main results that have been accomplished with respect to the plasma source characteristics, deposition process and the properties of the gas diffusion barrier film.
Keywords: dielectric barrier discharge, PECVD, moisture barrier, silica thin film
Barrier Deposition Processes
Emerging applications in flexible and printed electronics urgently demand new transparent encapsulation materials to limit the ingress of environmental oxidizers such as moisture and oxygen, thus ensuring prolonged lifetime stability of the device components. Aforesaid device encapsulation can be achieved by deposition of inorganic gas diffusion barrier layers on organic flexible polymeric substrates. Amongst the various thin film technologies, such as physical vapour deposition (PVD) and atomic layer deposition (ALD), plasma-enhanced chemical vapour deposition (PECVD) is a promising candidate for barrier layer processing due to good prospects to synthesise dense inorganic layers at relatively low temperatures and high throughput. At the same time the deposition of transparent gas diffusion barrier films on polymeric substrates can be considered as one of the grand challenges in thin film processing as it requires a high level of control over plasma uniformity, plasma-chemistry and power dissipation, which is not a trivial task under vacuum conditions but especially not at atmospheric pressure.
Since the moisture barrier requirements for flexible electronic application are orders of magnitude beyond the permeability of pristine polymer films having a Water Vapour Transmission Rate (WVTR) = 1-100 g-m^-day"1, the moisture barrier performance...