Enhancement of Ferroelectricity in Hf 0.5 Zr 0.5 O ₂ via Pre-Crystallization and Interface Engineering at Ultra-Low Temperature (300 °C) Annealing

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The interface degradation between ferroelectric film and surrounding layers limits the endurance of hafnia ferroelectric devices significantly. This letter proposes a promising TiN/TZHZT/TiN structure with TiO2/ZrO2 bi-interlayers on both sides of a sub-7 nm Hf0.5Zr0.5O2 (HZO). The TZHZT sample underwent ultra-low temperature annealing at 300 °C demonstrates exceptional ferroelectric properties, i.e. significant remnant polarization (2Pr=28.2 μC/cm2), appropriate coercive field (Ec=1.7 MV/cm), and excellent endurance exceeding 1010 cycles. Achieved results are attributed to the synergistic effects of dual interlayer engineering. Specifically, the ZrO2 interlayer promotes the growth of ferroelectric grains through the formation of seed crystals, leading to larger grain size after annealing. Meanwhile, the TiO2 interlayer enhances tensile stress and oxygen enrichment, thereby improving both 2Pr and endurance. Moreover, the ZrO2 interlayer effectively compensates the deficiency of breakdown strength for TiO2 layer.