Impact of Unintentional Oxygen Incorporation on Leakage Behavior and Fatigue Endurance of Al1‐xScxN1‐yOy Ferroelectric Films

Abstract Aluminum scandium nitride (AlScN) attracts significant attention for its excellent ferroelectric properties and complementary metal‐oxide‐semiconductor (CMOS) compatibility. However, unintentional oxygen incorporation during deposition significantly influences the leakage behavior and fatigue endurance of the films, while the underlying physical mechanisms remain unclear. In this study, AlScN films with varying oxygen levels are fabricated by adjusting the N 2 /Ar ratio during co‐sputtering. All resulting devices exhibit polarization‐bound leakage (PBL) current—a non‐switching component unremovable by the conventional positive‐up‐negative‐down (PUND) method. The PBL current magnitude is highly negatively correlated with oxygen content, based on which a coupled mechanism is proposed, linking domain‐wall‐motion‐induced migration of O N defects during polarization switching to the resulting leakage behavior. A defect migration model under electric field modulation preliminarily validates this mechanism theoretically. Fatigue tests reveal clear oxygen content dependence: lower‐oxygen devices exhibit superior fatigue endurance and further improve in oxygen‐free test conditions. The migration and redistribution of O N defects serve as the dominant factors in device fatigue breakdown, which further experimentally validates the proposed coupling mechanism. These findings clarify the critical role of oxygen in the leakage behavior and fatigue endurance of AlScN‐based ferroelectric devices, advancing the development of high‐reliability AlScN ferroelectric devices.