Abstract: The low-temperature processed (≤ 450 °C) HfO₂-based ferroelectric thin films (FE-HfO₂) bring about unprecedented possibilities of implementing ultra-low-power computing and electronic systems due to the capability of back-end-of-line (BEOL) embedded integration. Nevertheless, the FE-HfO₂ continues to face significant challenges, including small polarization, slow switching speed, and poor endurance at low operating voltages. Here we report a breakthrough in 5-nm-thick Hf_0.5Zr_0.5O₂ (HZO) film fabricated at 450 °C through an innovative ZrO₂-starting atomic layer deposition process, achieving unprecedented simultaneous improvements in polarization, switching speed, and endurance properties. Through comprehensive in-situ high-temperature X-ray diffraction analysis and pulse switching experiments, we elucidate that these enhancements stem from the reduced crystallization temperature and the optimized interfacial layer. Remarkably, the HZO films exhibit state-of-the-art performance metrics at ultralow operating voltages (0.9-1.6 V), featuring a substantial remanent polarization (P_r) of 19.6 µC/cm², fast operation speed (< 100 ns), and exceptional endurance exceeding 5 × 10⁹ cycles with minimal polarization degradation (20% 2P_r loss). This work represents a pivotal advancement toward the realization of high-performance, high-density, and BEOL-compatible ferroelectric devices for next-generation computing applications.

Key words: BEOL-embedded integration, Ferroelectric thin films, HZO thin films, Polarization switching speed, Endurance