Takashi Onaya received his Ph.D. degree from Meiji University, Japan, in 2021. From 2019 to 2020, he was a visiting researcher at the University of Texas at Dallas, USA. From 2021 to 2022, he served as a Postdoctoral (PD) Research Fellow of the Japan Society for the Promotion of Science (JSPS) at National Institute of Advanced Industrial Science and Technology (AIST), Japan. From 2022 to 2024, he was an assistant professor at the University of Tokyo, Japan. In 2025, he joined National Institute for Materials Science (NIMS). His research interests include ALD techniques for ferroelectric HfO₂-based films and high-k dielectric films for semiconductor devices.

Ferroelectric HfO₂-based materials have attracted significant attention since the first report of their ferroelectricity in 2011 [1], due to their excellent CMOS compatibility, thickness scalability (<10 nm), and low thermal budget (<400C) [2]. However, HfO₂-based ferroelectric devices face serious reliability issues in practical applications, such as fatigue and hard breakdown during electric field cycling [3]. These endurance degradations were thought to be caused by the formation of defects such as oxygen vacancies (V_O) in HfO₂-based films during electric field cycling [4]. In addition, our previous study reported that one of the origins of additional V_O formation could be a field-induced interface reaction accompanied by oxygen diffusion from the HfO₂-based film to the TiN electrodes [5].

In this presentation, to prevent oxygen diffusion induced by field-induced interface reactions, we will present interface design guidelines using an oxide semiconductor interfacial layer as an oxygen blocking layer inserted between the HfO₂-based film and the electrode. Furthermore, to discuss the requirements for these interfacial layers, we will show experimental results on how the bond dissociation energies (BDEs) between metal and oxygen atoms in these interfacial layers affect device reliability.

1. T. S. Böscke et al., Appl. Phys. Lett. 99, 102903 (2011). DOI: 10.1063/1.3634052
2. T. Onaya et al., APL Mater. 9, 031111 (2021). DOI: 10.1063/5.0035848
3. M. Pešić et al., Adv. Funct. Mater. 26, 4601 (2016). DOI: 10.1002/adfm.201600590
4. W. Hamouda et al., Appl. Phys. Lett. 120, 202902 (2022). DOI: 10.1063/5.0093125
5. T. Onaya et al., Solid-State Electron. 210, 108801 (2023). DOI: 10.1016/j.sse.2023.108801