Fabrication and Characterization of SiOx/Parylene and SiNx/Parylene Thin Film Encapsulation Layers

Successful commercialization of flexible organic electronic devices is largely dependent on proper encapsulation that protects them from permeation of oxygen and water vapor. At present, low permeation encapsulation materials generally consist of multilayer films of organic/inorganic materials which can be deposited by plasma enhanced chemical vapor deposition (PECVD), atomic layer deposition (ALD), and vapor phase deposition. For this study, we report the effective water vapor transmission rates (WVTR) for multilayer thin films consisting of low temperature PECVD deposited SiNx and SiOx combined with a parylene organic layer. The effective WVTR was measured as a function of the number of bilayer pairs using Ca corrosion tests. The effective WVTR at 20 °C and 50% relative humidity [RH] for three bilayer pairs of SiOx/parylene ranged between 4.4–8.0 × 10⁻⁴ g/m²/day while SiNx/parylene had a transmission rate 1.3×10⁻⁴ g/m²/day. In general, additional layers were found to decrease the permeation rates to as low as 3.9×10⁻⁵ g/m²/day, while the SiNx/parylene coatings performed the best overall.