The Imprint Failure and Suppression of the Multi‐Level Memory in HfAlO _x Ferroelectric Capacitor

Abstract Multi‐level HfO ₂ ‐based ferroelectrics demonstrate considerable potential for next‐generation data storage systems. However, their application faces critical reliability limitations due to the pronounced imprint effect. This study systematically investigates imprint‐induced operational deviations in 2‐bit/cell HfAlO _x ferroelectric capacitors, revealing significant coercive voltage shifts within minutes at room‐temperature that substantially compromise intermediate state re‐writing accuracy. First‐order reversal curve analysis quantitatively resolves the imprint‐generated internal electric field distribution, while impedance spectroscopy and X‐ray photoelectron spectroscopy identify charged oxygen vacancies as the dominant imprint mechanism. Phase‐field simulations further unveil how internal electric fields alter domain switching dynamics through temporally advanced and retarded polarization reversal, directly explaining the distorted hysteresis behavior and intermediate state re‐writing failures. To mitigate this critical issue, a pre‐programming protocol enabling controlled oxygen vacancy charge redistribution is developed, achieving precise intermediate states programming under room‐temperature operation. The mechanistic understanding and imprint suppression method presented in this work provides critical insights for advancing the reliability of HfO ₂ ‐based ferroelectric memory devices toward practical multi‐level storage applications.