Growth and Characterization of BeO Thin Films Grown by Atomic Layer Deposition Using H2O and O3 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 O3, are governed by different reaction mechanisms, resulting in different film properties. At growth temperatures ranging from 150 to 300 °C, the properties of the BeO films grown using H2O are temperature-independent. In contrast, the BeO films grown using O3 at low temperatures (<200 °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 O3 at low temperatures (<200 °C) show a decreased band gap (Eg: 7.7-7.9 eV) and dielectric constant (εr: 5.6-6.7). Above 250 °C, these properties recovered to the levels (Eg ∼ 9.4 eV and εr ∼ 8.1) of the BeO films grown using H2O, which show high values of Eg ∼ 9.1-9.4 eV and εr ∼ 8. Collectively, these findings demonstrate that the O3-ALD process requires relatively more thermal energy than H2O-ALD does, to produce high-quality BeO films.