Deposition and permeation properties of SiNX/parylene multilayers on polymeric substrates

Silicon nitride (SiNX) deposited on flexible polycarbonate (PC) substrates by plasma-enhanced chemical vapor deposition have been investigated for thin-film barrier applications via the water vapor transmission rate (WVTR) and oxygen transmission rate (OTR) measurements. A cyclic bending test was used to get quantitative information about the OTR and WVTR data of the single thin brittle SiNx/PC film with various thicknesses (50-400 nm). It was found that the SiNx/PC sample with a thickness of 100 nm possessed a minimum saturated crack density, as evidenced by the lowest OTR/WVTR values after the cyclic bending test. To improve the barrier performance, a smoothing, defect-decoupling organic film (parylene) was deposited on the top of the SiNx layer. The degradation after the cyclic bending test for the parylene/SiNx/PC structure was improved more than one order of magnitude as compared with that for the SiNx/PC sample. After 3000-times cyclic bending, the WVTR and OTR of the two pairs of parylene/SiNx, coatings on PC can be maintained at a level near 0.01 g/m(2)/day and 0.1 cc/m(2)/day, respectively (below the detection limits of the MOCON systems). These indicate that the present multilayered coatings have high potential for future flexible display applications. (c) 2005 Elsevier B.V. All rights reserved.