Low temperature growth of Beryllium Oxide thin films prepared via plasma enhanced atomic layer deposition

Beryllium oxide (BeO) is a unique metal oxide that exhibits high thermal conductivity and a high dielectric constant, even though it has a large bandgap energy. These characteristics can potentially address the electromagnetic issues associated with contemporary nanoscale electronic devices. However, BeO is mainly used as a heat-dissipating and refractory layer in sintering powders. To extend the use of BeO in semiconductor front-end-of-line processes, we developed nanoscale BeO thin films by using state-of-the-art atomic layer deposition (ALD). The physical and electrical properties of the BeO thin films were evaluated by introducing O₂ plasma and H₂O vapor as oxidation sources for the ALD process. A controlled plasma-enhanced ALD (PEALD) process led to the production of c-axis grown crystalline wurtzite BeO (0 0 2) films with a high growth rate per cycle at low substrate temperatures. The plasma energy was found to be adequately compensate for the high substrate temperature required for thermal ALD (ThALD). The bandgap energy (7.9 eV), calculated via inelastic energy loss analysis, and the dielectric constant (8.75) and breakdown voltage (10.3 MV/cm), obtained from MOS capacitors, are optimal for nanoscale electronic device applications.