Use of a New Non-Pyrophoric Liquid Aluminum Precursor for Atomic Layer Deposition

Xueming Xia; Alaric Taylor; Yifan Zhao; Stefan Guldin; Chris Blackman

doi:10.3390/ma12091429

Use of a New Non-Pyrophoric Liquid Aluminum Precursor for Atomic Layer Deposition

Materials (Basel). 2019 May 2;12(9):1429. doi: 10.3390/ma12091429.

Authors

Xueming Xia¹, Alaric Taylor², Yifan Zhao³, Stefan Guldin⁴, Chris Blackman⁵

Affiliations

¹ Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK. xueming.xia.16@ucl.ac.uk.
² Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK. alaric.taylor@ucl.ac.uk.
³ Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK. yifan.zhao15@imperial.ac.uk.
⁴ Department of Chemical Engineering, University College London, Torrington Place, London WC1E 7JE, UK. s.guldin@ucl.ac.uk.
⁵ Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK. c.blackman@ucl.ac.uk.

Abstract

An Al₂O₃ thin film has been grown by vapor deposition using different Al precursors. The most commonly used precursor is trimethylaluminum, which is highly reactive and pyrophoric. In the purpose of searching for a more ideal Al source, the non-pyrophoric aluminum tri-sec-butoxide ([Al(O^sBu)₃], ATSB) was introduced as a novel precursor for atomic layer deposition (ALD). After demonstrating the deposition of Al₂O₃ via chemical vapor deposition (CVD) and 'pulsed CVD' routes, the use of ATSB in an atomic layer deposition (ALD)-like process was investigated and optimized to achieve self-limiting growth. The films were characterized using spectral reflectance, ellipsometry and UV-Vis before their composition was studied. The growth rate of Al₂O₃ via the ALD-like process was consistently 0.12 nm/cycle on glass, silicon and quartz substrates under the optimized conditions. Scanning electron microscopy and transmission electron microscopy images of the ALD-deposited Al₂O₃ films deposited on complex nanostructures demonstrated the conformity, uniformity and good thickness control of these films, suggesting a potential of being used as the protection layer in photoelectrochemical water splitting.

Keywords: aluminum oxide; aluminum tri-sec-butoxide; atomic layer deposition; chemical vapor deposition; thin film.