Impact of the Crystal Structure of Interlayer on the Properties of Zr‐Doped Hafnia‐Based Ferroelectric Capacitor

In this work, the effect of interlayer on the ferroelectric properties of Hf 0.5 Zr 0.5 O 2 (HZO)‐based metal–ferroelectric–metal (MFM) capacitor is investigated. In detail, a 1 nm thick interlayer of amorphous Al 2 O 3 and fluorite‐structured ZrO 2 is inserted in the HZO ferroelectric film. Grazing incidence X‐ray diffraction (GIXRD) analysis reveals that the amorphous structure of Al 2 O 3 (vs. the fluorite‐structured ZrO 2 ) effectively blocks the grain boundary growth of HZO layer. In contrast, X‐ray photoelectron spectroscopy (XPS) analysis demonstrates that ZrO 2 with a fluorite structure like HZO induces fewer oxygen vacancies at the ferroelectric–insulator interface, and thereby, it provides fewer defects in the HZO layer, achieving fatigue‐free endurance characteristics and a higher remanent polarization (2 P r ) of 4.6 μC cm −2 .