Fast spatial atomic layer deposition of Al2O3 at low temperature (˂ 100 degrees C) as a gas permeation barrier for flexible organic light-emitting diode displays

Abstract

The authors developed a high throughput (70 angstrom/min) and scalable space-divided atomic layer deposition (ALD) system for thin film encapsulation (TFE) of flexible organic light-emitting diode (OLED) displays at low temperatures (˂100 degrees C). In this paper, the authors report the excellent moisture barrier properties of Al2O3 films deposited on 2G glass substrates of an industrially relevant size (370 x 470 mm(2)) using the newly developed ALD system. This new ALD system reduced the ALD cycle time to less than 1 s. A growth rate of 0.9 angstrom/cycle was achieved using trimethylaluminum as an Al source and O-3 as an O reactant. The morphological features and step coverage of the Al2O3 films were investigated using field emission scanning electron microscopy. The chemical composition was analyzed using Auger electron spectroscopy. These deposited Al2O3 films demonstrated a good optical transmittance higher than 95% in the visible region based on the ultraviolet visible spectrometer measurements. Water vapor transmission rate lower than the detection limit of the MOCON test (less than 3.0 x 10(-3) g/m(2) day) were obtained for the flexible substrates. Based on these results, Al2O3 deposited using our new high-throughput and scalable spatial ALD is considered a good candidate for preparation of TFE films of flexible OLEDs. (C) 2015 American Vacuum Society.