Growth and Characterization of BeO Thin Films Grown by Atomic Layer Deposition Using H2O and O-3 as Oxygen Sources

Abstract

Growth characteristics and properties of BeO films grown by atomic layer deposition (ALD) are investigated. ALD chemistries between dimethylberyllium and two different oxygen sources, H2O and O-3, are governed by different reaction mechanisms, resulting in different film properties. At growth temperatures ranging from 150 to 300 degrees C, the properties of the BeO films grown using H2O are temperature-independent. In contrast, the BeO films grown using O-3 at low temperatures (<200 degrees C) show high concentrations of carbon and hydrogen, possibly owing to the incomplete removal of the ligands of the precursor, leading to a low film density. This correlates with the evolution of the rough surface and the microstructure composed of few nanometer-sized grains. The low-quality BeO films grown using O-3 at low temperatures (<200 degrees C) show a decreased band gap (E-g: 7.77.9 eV) and dielectric constant (epsilon(r): 5.66.7). Above 250 degrees C, these properties recovered to the levels (E-g similar to 9.4 eV and epsilon(r) similar to 8.1) of the BeO films grown using H2O, which show high values of E-g similar to 9.19.4 eV and epsilon(r) similar to 8. Collectively, these findings demonstrate that the O-3-ALD process requires relatively more thermal energy than H2O-ALD does, to produce high-quality BeO films.