Effects of Polarization Behavior on Wake-Up and Fatigue of Hafnium-Based Ferroelectric Thin Films

The pronounced wake-up and fatigue phenomena in HfO₂-based ferroelectric materials present significant reliability challenges, limiting their potential in microelectronic applications. In this study, high-quality (Hf, Zr)O₂ (HZO) thin-film capacitors are fabricated and their ferroelectric behavior is systematically explored under unipolar and bipolar electric field cycling. It is observed that transient overshoot during polarization switching under bipolar fields induces metal─O (Hf─O/Zr─O) bond breakage, creating oxygen vacancy defects that cause inevitable fatigue and increased leakage current. Conversely, under unipolar high-voltage fields—both positive and negative—the remanent polarization increases linearly with cycling, with no significant rise in leakage current. Phase-field simulations reveal that unipolar high fields activate non-switching ferroelectric domains, enabling domain reversal at lower fields. Leveraging this insight, a preconditioning wake-up treatment with unipolar high-voltage fields is performed, achieving an impressive 2P_r of ≈45 µC cm⁻² at an operating voltage of just 2 MV cm⁻¹. Even after ≈2 × 10¹⁰ cycles, the capacitors maintain a robust operational window with 2P_r ≈33 µC cm⁻². These findings introduce a novel mechanism for wake-up and fatigue in HZO thin films, suggesting these effects arise from the competition between domain depinning and intrinsic defect formation, thereby providing new insights into the fundamental processes driving these phenomena.