We report the record-high remanent polarization value (2P r ~55 μC/cm 2 ) at an ultra-low operating voltage (0.5 V) with effective 3 nm hafnium zirconium oxide (HZO) capacitors. This exceptional ferroelectric property is achieved at a back-end-of-line (BEOL) compatible temperature below 400°C. Moreover, our devices demonstrate configurable ferroelectric saturation characteristics, ensuring reliable and reproducible switching polarization states $(\mathrm{P}_{\text{sw}})$ . These results potentially allow the design of novel ferroelectric device circuitry. This study highlights the feasibility of extremely low-power ferroelectric applications beyond 0.5 V operation in BEOL.

In this report, we discuss methods for obtaining the orthorhombic phase in hafnia-based materials, a necessary condition for the emergence of ferroelectricity. Those methods, including stress engineering with a top electrode, high-pressure annealing, and physical/chemical densification through controlled deposition conditions, can be performed at temperatures suitable for integration into BEOL 3D structures and flexible, wearable technologies. By successfully implementing these techniques, hafnia-based ferroelectric materials can be utilized in a variety of advanced applications.

In this study, the thermal budget of atomic layer deposited Hf 0.5 Zr 0.5 O 2 (HZO) thin films have been investigated for memory applications. Specifically, using a furnace as a crystallization method of the HZO thin film, TiN/HZO/TiN capacitors were fabricated under various annealing temperature (300-500°C) and time (1–48 h) conditions. As a result, although the annealing time needs to be increased, the ferroelectric properties with robust endurance were realized by lowering the annealing temperature.