Gas diffusion ultrabarriers on polymer substrates using Al2 O3 atomic layer deposition and SiN plasma-enhanced chemical vapor deposition

Abstract

Thin films grown by Al2 O3 atomic layer deposition (ALD) and SiN plasma-enhanced chemical vapor deposition (PECVD) have been tested as gas diffusion barriers either individually or as bilayers on polymer substrates. Single films of Al2 O3 ALD with thicknesses of 10 nm had a water vapor transmission rate (WVTR) of ≤5× 10 -5 g/ m2 day at 38 °C/85% relative humidity (RH), as measured by the Ca test. This WVTR value was limited by H2 O permeability through the epoxy seal, as determined by the Ca test for the glass lid control. In comparison, SiN PECVD films with a thickness of 100 nm had a WVTR of ∼7× 10-3 g/ m2 day at 38 °C/85% RH. Significant improvements resulted when the SiN PECVD film was coated with an Al2 O3 ALD film. An Al2 O3 ALD film with a thickness of only 5 nm on a SiN PECVD film with a thickness of 100 nm reduced the WVTR from ∼7× 10-3 to ≤5× 10 -5 g/ m2 day at 38 °C/85% RH. The reduction in the permeability for Al2 O3 ALD on the SiN PECVD films was attributed to either Al2 O3 ALD sealing defects in the SiN PECVD film or improved nucleation of Al2 O3 ALD on SiN. © 2009 American Institute of Physics.