Alumina films as gas barrier layers grown by spatial atomic layer deposition with trimethylaluminum and different oxygen sources

Abstract

Alumina layers were grown from trimethylaluminum (TMA) and water, ozone as well as an oxygen plasma as co-reactants in low temperature spatial atomic layer deposition (ALD). The influence of the amount of precursor, the precursor exposure duration, and substrate temperature were investigated with respect to the growth rate while employing different oxygen sources. The TMA/water process provided alumina (AlOx) films with superb film quality as shown by infrared measurements. Ozone-based processes allowed lower substrate temperatures. Nevertheless, carbon residuals in different binding states were found within the bulk material. However, the carbon impurities have no impact on the barrier performance, since 50 nm AlOx grown by TMA either with water or ozone exhibited a water vapor transition rate in the range of 10−6 g/m2/day. However, when our home-built microwave plasma source was applied in a remote configuration, the water vapor transition rate was one order of magnitude higher due to a reduction in film quality. Furthermore, a TMA utilization of ∼50% demonstrated the highly cost-effective spatial ALD concept as a deposition technique which is very suitable for industrial deposition applications.

Speeding up the unique assets of atomic layer deposition

“…To date, SALD has been extensively used for encapsulation, to protect devices or to fabricate gas diffusion barriers, both in rigid and flexible substrates, including paper, as detailed below. [44,48,64,[66][67][68][69][70][71][72][73] Choi et al have demonstrated Al2O3 deposition rates as high as 7 nm/min (0.12 nm/s) at temperatures below 100 °C. The SALD system they have developed is coupled to a glove box and can coat substrates of industrial size (370 x 470 mm 2 ).…”

Influence of the Geometric Parameters on the Deposition Mode in Spatial Atomic Layer Deposition: A Novel Approach to Area-Selective Deposition

“…This spatially separated exposure of the substrate is equivalent to the temporal ALD cycles and achieves comparable materials properties when the materials deposited are not sensitive to the atmosphere [7]. SALD has been tested before by several groups to deposit a wide variety of functional oxides in a homogeneous and conformal manner, in many cases taking place at atmospheric pressure [8][9][10].…”

“…Numerous approaches have been explored to successfully generate the mentioned spatial regions needed, without intermixing the gaseous precursors in SALD [9][10][11][12]. Specifically, the approach used in our laboratory (a home-made system presented and explained in detail in [4]) is based on a patent published by Kodak [13] that led to the publication of scientific papers using the spatial separation ALD concept by the same group from 2008 [4].…”

Thin film encapsulation for the organic light-emitting diodes display via atomic layer deposition

“…The barrier property of the PEN substrates coated with 100-nm-thick nanolaminates improved from 1.8 Â 10 À3 to 6.9 Â 10 À5 g/m 2 Áday [137]. Franke et al developed their SALD system integrated with a microwave plasma source, and the WVTR value of 50 nm Al 2 O 3 could reach ;10 À6 g/m 2 Áday [56]. Due to the simplicity of the linear track one, we also developed the modular injector integrated SALD apparatus, and the deposition rate reached 100 nm/min with the nonuniformity around 2% [138].…”