High-Performance Oxide Thin-Film Transistors with Atomic Layer Deposition-Grown HfO₂/BeO Hetero-Dielectric

Atomic layer deposition-grown beryllium oxide (BeO) is gaining attention as a dielectric material that can minimize device power consumption because of its high dielectric constant, high thermal conductivity, and low leakage current enabled by its wide bandgap energy. In this study, the impact of BeO dielectrics on InSnZnO (ITZO) thin-film transistors (TFTs) was investigated, revealing that adding a hafnium dioxide (HfO₂) layer can enhance electrical performance and bias stress reliability. Time-of-flight secondary-ion mass spectrometry and X-ray photoelectron spectroscopy confirmed that the single-BeO dielectric-based ITZO TFTs exhibited a low mobility of 27.6 cm²/V·s due to Be migration and demonstrated abnormal threshold voltage (V_TH) shifts under bias stress. Conversely, the HfO₂ 20 nm/BeO hetero-dielectric ITZO TFTs exhibited a high mobility of 76.6 cm²/V·s and enhanced abnormal V_TH shift characteristics. Therefore, these results demonstrate that our high-performance HfO₂/BeO hetero-dielectric-based ITZO TFTs could be utilized in back-end-of-line devices for monolithic three-dimensional memory technologies.