Effect of Annealing Ramp-Up Rate on the Ferroelectric Properties of Hf0.5Zr0.5O2 Capacitors

초록

Thermal annealing critically affects ferroelectric phase formation in HfO2-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 Hf0.5Zr0.5O2 (HZO) capacitors. When the ramp-up rate to 400 degrees C is controlled, capacitors annealed at rates of >= 200 degrees C/h exhibit saturated hysteresis loops with remanent polarization (2P r) above 40 mu C/cm2 and robust endurance up to 5 & times; 108 switching cycles, whereas those annealed at a rate of 100 degrees C/h show suppressed 2P 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.

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