| AVS 59th Annual International Symposium and Exhibition | |
| Plasma Science and Technology | Wednesday Sessions |
| Session PS+TC-WeM |
| Session: | Atmospheric Plasma Processing for PV, Flexible Electronics (incl. R2R) |
| Presenter: | S. Welzel, Eindhoven University of Technology, Netherlands |
| Authors: | S. Welzel, Eindhoven University of Technology, Netherlands S.A. Starostin, FUJIFILM Manufacturing Europe B.V., Netherlands H. de Vries, FUJIFILM Manufacturing Europe B.V., Netherlands M.C.M. van de Sanden, Eindhoven University of Technology, Netherlands R. Engeln, Eindhoven University of Technology, Netherlands |
| Correspondent: | Click to Email |
Large-area plasma-enhanced roll-to-roll processing of polymeric substrates in diffusive dielectric barrier discharges (DBDs) have been shown to yield high-quality SiO2-like barrier layers. This has been obtained through chemical vapour deposition at atmospheric pressure using organo-silicon precursors (HMDSO or TEOS) and industrially relevant air-like gas mixtures (N2/O2/Ar). Provided an electronic stabilisation circuit is applied, high currents in different diffusive discharge modes can be achieved without admixtures of Helium. Earlier, extensive surface analysis studies of the synthesised layers revealed a competion between deposition and etching regimes throughout the active plasma zone and led to the development of a deposition model.
This contribution is concerned with complementary studies of the gas phase composition using infrared absorption techniques. Given the challenging optical access to DBDs with gap distances smaller than 1 mm in industrial-like roll-to-roll configuration a gas sampling system was implemented to collect a fraction of the effluent into a multiple pass absorption cell. Main stable products were identified under various discharge conditions such as different O2 admixtures and (average) power densities. Broadly speaking, a typical H-N-O chemistry in the presence of traces of hydrocarbons is observed for such high-current DBDs. To establish a link to earlier model assumptions both dominant etching and deposition conditions were studied separately (i.e. precursor absent and added, respectively). Formic acid (HCOOH) was found to be a good marker molecule in the gas phase for strong etching of the polymeric substrate or incomplete precursor dissociation. Particularly, the appearance of precursor fragments in the infrared gas phase spectra can be correlated to the injected power and growth rate. Under conditions of complete precursor depletion the effluent zone of the reactor resembles an air-like plasma where NO2, NO, N2O and HNO2 are observed whilst hydrocarbons or alcohols are absent.