Ultrafast Switching Speed Demonstrated in Wafer-Scale Integration of Crystalline Undoped HfO₂-Based Ferroelectrics

Hafnium oxide-based ferroelectric materials have been researched extensively for high-speed, low-power nonvolatile memory devices. However, doping HfO₂ through atomic layer deposition (ALD) cycles primarily aims to enhance specific properties but also introduces challenges in balancing performance and reliability. Therefore, understanding the properties of intrinsic crystalline HfO₂-based ferroelectric materials and developing undoped HfO₂ ferroelectric devices with exceptional comprehensive properties are crucial. Here, we successfully fabricated well-engineered undoped HfO₂ ferroelectric devices with high endurance (>10¹¹ cycles), large grain size (>60 nm), and ultrahigh switching speed (∼1 ns). The results indicate that controlling the oxygen partial pressure can regulate the concentration of oxygen vacancies (V_O), thereby stabilizing the ferroelectric phase. Finally, a comprehensive study of device variability is conducted, confirming a low device to device (D2D) variation. The outstanding comprehensive performance will enhance confidence in undoped HfO₂ as a viable candidate for ferroelectrics in VLSI applications.