Oxygen Vacancy Engineering for BEOL-Compatible Thickness-Scaled Hafnia Ferroelectrics

Abstract Driven by the application demands of intelligent computing and edge devices, hafnia-based ferroelectric memories are evolving toward low-voltage operation and improved energy efficiency. Reducing the thickness of the ferroelectric layer is considered an effective approach to achieving these objectives. This study focuses on the critical issue of polarization degradation during thickness scaling of hafnia-based ferroelectric films and suggests that oxygen vacancy concentration may be an important factor associated with this degradation. Based on this hypothesis, an oxygen vacancy regulation strategy is implemented in BEOL-compatible ferroelectric capacitors with 6 nm Hf 0.5 Zr 0.5 O 2 films, achieving low-voltage operation (1.2 V) and excellent endurance (2P r of 22.2 μC·cm -2 retained after 10 10 switching cycles). This study provides experimental support and a possible design guideline for hafnia-based ferroelectric devices targeting applications at advanced technology nodes.