| Summary: | This work systematically investigates the impact of a pre-annealed ZrO<sub>2</sub> interfacial layer on the ferroelectric behavior of Hf<sub>0.5</sub>Zr0.<sub>5</sub>O<sub>2</sub> (HZO) capacitors. The remanent polarization (2Pr) value of HZO capacitors, including configurations such as W/HZO/TiN/p<sup>+</sup> Si, W/HZO/(pre-annealed) ZrO<sub>2</sub>/TiN/p<sup>+</sup> Si, W/HZO/SiO<sub>2</sub>/TiN/p<sup>+</sup> Si, and W/HZO/SiO<sub>2</sub>/p<sup>+</sup> Si, exhibits significant variations. The W/HZO/(pre-annealed) ZrO<sub>2</sub>/TiN/p<sup>+</sup> Si capacitor demonstrates superior ferroelectric performance, with a 2Pr value of ~32 µC/cm<sup>2</sup>. Furthermore, by optimizing the thickness combination of HZO and the pre-annealed ZrO<sub>2</sub> interfacial layer, a capacitor with a 10 nm HZO and 2 nm ZrO<sub>2</sub> achieves the largest 2Pr value. The pre-annealing process applied to ZrO<sub>2</sub> is found to play a very important role in inducing the orthorhombic phase and thus enhancing ferroelectricity. This enhancement is attributed to the pre-annealed 2 nm ZrO<sub>2</sub> interfacial layer acting as a structural guide for the subsequent HZO orthorhombic phase, thereby improving the ferroelectric performance of HZO capacitors. These findings provide a comprehensive explanation and experimental verification of the impact of pre-annealed ZrO<sub>2</sub> on ferroelectric devices, offering novel insights for the optimization of ferroelectric properties.
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