Gas Diffusion Barriers Prepared by Spatial Atmospheric Pressure Plasma Enhanced ALD

In this work, we report on aluminum oxide (Al₂O₃) gas permeation barriers prepared by spatial ALD (SALD) at atmospheric pressure. We compare the growth characteristics and layer properties using trimethylaluminum (TMA) in combination with an Ar/O₂ remote atmospheric pressure plasma for different substrate velocities and different temperatures. The resulting Al₂O₃ films show ultralow water vapor transmission rates (WVTR) on the order of 10^-6 gm^-2d^-1. In notable contrast, plasma based layers already show good barrier properties at low deposition temperatures (75 °C), while water based processes require a growth temperature above 100 °C to achieve equally low WVTRs. The activation energy for the water permeation mechanism was determined to be 62 kJ/mol.