| AVS 63rd International Symposium & Exhibition | |
| Thin Film | Friday Sessions |
| Session TF-FrM |
| Session: | CVD, ALD and Film Characterization |
| Presenter: | Anna Meshkova, FOM Institute DIFFER, Netherlands |
| Authors: | A.S. Meshkova, FOM Institute DIFFER, Netherlands F.M. Elam, FUJIFILM Manufacturing Europe, Netherlands S.A. Starostin, FUJIFILM Manufacturing Europe, Netherlands M.C.M. van de Sanden, FOM Institute DIFFER, Netherlands H.W. de Vries, FOM institute DIFFER, Netherlands |
| Correspondent: | Click to Email |
It was recently demonstrated that high quality dense inorganic oxide films can be synthesized on polymers utilizing the roll-to-roll Atmospheric Pressure PECVD process assisted by the diffuse dielectric barrier discharge (DBD) between cylindrical drum electrodes. In such a reactor configuration the local deposition rate as well as the local plasma chemistry is highly non-uniform along the gas flow due to the depletion of the precursor and spatial-temporal non uniformity of the discharge.
It is therefore expected that the properties of the film will vary depending on deposition location within the reactor. Hence the analysis of the spatially averaged layer deposited on the substrate roll-to-roll transported through the active reactor length is not sufficient for understanding the film growth process. The aim of the present contribution, therefore, is to study the local kinetics, gas phase transport and film growth mechanisms by means of spatially resolved analysis of the film properties in the gas flow direction of the AP-PECVD reactor, by analysis of the deposition rate profile, morphology, chemical composition and microstructure.
The set of SiO2 films was grown in an AP-PECVD reactor with parallel bi-axial cylindrical electrode geometry on PEN foil. TEOS was used as a precursor for silica-like thin films and the process gasses were argon, nitrogen and oxygen. The variation the of deposition rate along the gas flow was accessed by measuring the film thickness profile by means of a focused beam SE with a beam size of 120 µm. The composition and microstructure was analysed by spatially resolved XPS and ATR-FTIR.
Surprisingly it was found that deposition rate profile along the gas flow has two distinct maxima. The presence of two maxima indicates a difference in the transport kinetics of the precursor fragments arriving to the surface. This coincides well with the observed variation in film microstructure in the downstream direction, assessed by ATR-FTIR analysis, with higher network porosity for lower gas residence time and denser films deposited in high residence time regions. This spatial non-uniformity within the reactor results in a depth gradient of the film properties synthesized on web-rolled substrate. One can conclude that, for the studied AP-PECVD process, the film density will increase from the silica/polymer interface towards silica/air interface when the polymer substrate is transported along gas flow. By controlling the gas flow speed the density of the layer can be modified. The last observation is especially relevant regarding the design of the gas diffusion barrier layers.