Ferroelectric HfO₂ with excellent scaling capability and good complementary-metal-oxide-semiconductor (CMOS) technology compatibility has triggered the interest in nonvolatile memories. Here, (HfO₂-ZrO₂)₃/mAl₂O₃/ (HfO₂-ZrO₂)₃ (m donate the Al₂O₃ (AO) thickness) nanolaminates with different AO thicknesses were fabricated using atomic layer deposition method. Ferroelectricity and reliability were investigated by varying AO thickness in the deposition process. The highest remnant polarization (P_r) of 23.87 μC/cm² is obtained in (HZO)₃/1AO/(HZO)₃ nanolaminate with 1 nm-thick AO dielectric layer. The leakage current can be decreased by 2-3 orders of magnitude with the increase of AO thickness. The performance enhancement is ascribed to the interfacial polarization because of the dielectric mismatch between AO and HfO₂-ZrO₂ (HZO) and high breakdown strength of AO. The insertion of lower-permittivity AO can effectively modulate the distribution of electric field in nanolaminates and achieves a significant improvement in reliability. Improved ferroelectricity and reliability in ferroelectric/dielectric/ferroelectric structure pave a new way for the designation of HfO₂-based ferroelectric memories with broader thickness range.