Effect of scan speed on moisture barrier properties of aluminum oxide using spatial atomic layer deposition

Abstract

Atomic layer deposition (ALD) has been shown to produce high-quality thin films with superior moisture barrier performance on polymer substrates. However, the conventional time-sequenced mode is incompatible with industrial needs due to its low deposition rate. One solution to overcome this throughput issue is to use spatial ALD. Recently, various approaches have been reported. The authors also developed a fast spatial ALD system using an industrial 2G (370 x 470mm²) glass substrate. Using this system, the authors investigated the effect of a scan speed on the moisture barrier properties of aluminum oxide (Al₂O₃) thin films. While the scan speeds were varied over a wide range of 100-800 mm/s, the water vapor transmission rate increased only slightly, from 1.4 x 10⁻³ to 3.0 x 10⁻³ g/m²/day. At a scan speed of 800 mm/s, the deposition rate was 70 angstrom/min, which was about seven times higher than that of conventional ALD. Moreover, the physical and chemical properties of the thin films slightly worsened with the increase in the scan speed. Based on the above results, Al2O3 thin films prepared using the newly developed high- throughput and scalable spatial ALD system are a promising candidate for thin film encapsulation of large-scale flexible electronic applications.