Plasma-deposited silicon oxide barrier films on polyethersulfone substrates: Temperature and thickness effects

D. S. Wuu*, W. C. Lo, C. C. Chiang, H. B. Lin, L. S. Chang, Ray-Hua Horng, C. L. Huang, Y. J. Gao

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


Silicon oxide (SiOx) films deposited on flexible polyethersulfone (PES) substrates by plasma-enhanced chemical vapor deposition (PEVCD) have been investigated for transparent barrier applications. Although the water vapor transmission rate (WVTR) of PES (∼28 g/m2/day; thickness: 200 μm) is higher than that of the polyethylene terephthalate (PET; ∼16 g/m2/day; thickness: 188 μm), the PES substrate can withstand process temperatures of up to 180 °C, providing more flexibility in the design of device processing. Details of the substrate-temperature and film-thickness effects on the SiOx/PES properties in terms of transmittance, refractive index, deposition rate, adhesion, roughness, and WVTR were described. When the substrate temperature increased from 80 to 170 °C, the deposition rate, adhesion, and roughness values were found to increase while the WVTR decreased to a value of near 0.3 g/m2/day at 150 °C. With increasing the oxide thickness from 50 to 500 nm, the surface roughness increased from 2.71 to 5.84 nm. A lower WVTR value can be achieved under a barrier thickness of 200 nm. Further improvement was carried out by depositing a 100-nm-thick SiOx film on both sides of the PES substrate, which resulted in a minimum WVTR of 0.1 g/m2/day. The double-sided coatings on PES could balance the stress and greatly improve the WVTR data.

Original languageEnglish
Pages (from-to)253-259
Number of pages7
JournalSurface and Coatings Technology
Issue number2-3
StatePublished - 22 Jul 2005


  • Gas barrier
  • Permeation
  • Polyethersulfone
  • Silicon oxide


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