| AVS 63rd International Symposium & Exhibition | |
| Advanced Surface Engineering | Tuesday Sessions |
| Session SE+MS+TF-TuA |
| Session: | Innovations in PVD, CVD, Atmospheric Pressure Plasma and Other Surface Technologies |
| Presenter: | Fiona Elam, FUJIFILM Manufacturing Europe B.V., Netherlands |
| Authors: | F.M. Elam, FUJIFILM Manufacturing Europe B.V., Netherlands A.S. Meshkova, DIFFER, Netherlands S.A. Starostin, FUJIFILM Manufacturing Europe B.V. J.B. Bouwstra, FUJIFILM Manufacturing Europe B.V. M.C.M. van de Sanden, Dutch Institute for Fundamental Energy Research (DIFFER), Netherlands H.W. de Vries, DIFFER, Netherlands |
| Correspondent: | Click to Email |
Atmospheric pressure-plasma enhanced chemical vapour deposition (AP-PECVD) is an innovative technology that can be integrated into many existing manufacturing systems to facilitate the mass production of functional films; specifically encapsulation foils. These barrier films are essential to the flexible electronics industry, envisioned to protect devices such as flexible solar cells and organic light emitting diodes against degradation from oxygen and water.
Roll-to-roll AP-PECVD was recently used to produce smooth, 90 nm silica bilayer thin films comprising a ‘dense layer’ and ‘porous layer’ that demonstrated exceptionally good encapsulation performance with effective water vapour transmission rates in the region of 6.9×10-4 g m2 day-1 (at 40oC, 90% relative humidity). By using the same material in the multilayer film architecture, and by having AP-PECVD as the deposition method, rendered this investigation highly industrially and commercially relevant to the eventual large scale production of flexible encapsulation foils. It was discovered that increasing the input energy per precursor gas molecule during the deposition of the dense layer, resulted in an improved encapsulation performance. However, the individual role performed by each layer in the overall success of the bilayer films is not yet fully understood, nor is the potential for energy conservation by varying process throughput.
A glow-like AP dielectric barrier discharge in a roll-to-roll set-up was used to deposit silica bilayer thin films onto a polyethylene 2,6 naphthalate substrate by means of PECVD. Tetraethyl orthosilicate (TEOS) was used as the precursor gas, together with a mixture of nitrogen, oxygen and argon. In each case, the deposition conditions for the synthesis of the dense layers were varied in order to study the effect of input energy per TEOS molecule and process throughput on the chemical composition and porosity of the layer. Deposition conditions for the porous layers were kept constant, with process throughput the only exception. Each film was characterised in terms of its water vapour transmission rate, its chemical composition and its morphology as a function of the input energy per TEOS molecule during the dense layer deposition and overall process throughput.
For the first time in AP-PECVD, it was found that the porous layer plays a critical role regarding encapsulation performance and surface smoothening of silica bilayer films. Due to increased throughput, the bilayer architecture also enables a 50% reduction in deposition energy consumption per barrier area, with respect to single layer silica films of equivalent encapsulation performance and thickness.