Effect of Annealing Ramp‐Up Rate on the Ferroelectric Properties of Hf _0.5 Zr _0.5 O ₂ Capacitors

Thermal annealing critically affects ferroelectric phase formation in HfO ₂ ‐based films and governs stabilization of the polar orthorhombic phase. Here, we demonstrate that the annealing ramp‐up rate strongly influences the polarization and endurance of ferroelectric Hf _0.5 Zr _0.5 O ₂ (HZO) capacitors. When the ramp‐up rate to 400 °C is controlled, capacitors annealed at rates of ≥200 °C/h exhibit saturated hysteresis loops with remanent polarization (2 P _r ) above 40 μC/cm ² and robust endurance up to 5 × 10 ⁸ switching cycles, whereas those annealed at a rate of 100 °C/h show suppressed 2 P _r and early endurance failure. Structural and electrical analyses indicate that a slow ramp‐up rate promotes the formation of the nonferroelectric monoclinic phase, whereas a rapid ramp‐up kinetically favors the stabilization of the ferroelectric orthorhombic phase. These findings establish the ramp‐up rate as a critical thermal processing parameter for optimizing phase formation and reliability in HZO. Importantly, the improved ferroelectric performance is achieved without additional process complexity while remaining fully compatible with a back‐end‐of‐line thermal budget.