Enhanced Ferroelectricity in Hf 1− X Zr X O 2 Thin Films Through Ultrathin Mo Electrode Layer and Microwave Annealing

Ferroelectric Hf 1− X Zr X O 2 (HZO) has emerged as a leading CMOS‐compatible material for next‐generation nonvolatile memories and logic devices due to its scalability, high remanent polarization (P r ), and robust endurance. However, achieving stable ferroelectricity in thin HZO films is hindered by the high crystallization temperature required for orthorhombic (o‐) phase formation, which exceeds the thermal budget of back‐end‐of‐line (BEOL) processes and causes severe interfacial damage. Although various low‐temperature annealing methods like laser or flash‐lamp treatments have been proposed, they often induce nonuniform heating and limited interfacial control, resulting in degraded polarization and reliability. Here, we demonstrate enhanced ferroelectricity in HZO thin films through a combined strategy of microwave annealing (MWA) and ultrathin Mo (5 nm) for interfacial engineering. The Mo interlayer effectively suppresses the suboxide portion in HZO, while MWA provides uniform volumetric heating via both thermal and dipole vibrational energy, enabling low‐temperature crystallization at 200°C. This synergistic process stabilizes o‐phase, yielding 2P r of 45.2 µC/cm 2 , and excellent endurance with fully satisfying BEOL compatibility requirements. These results establish a scalable interfacial engineering framework for realizing high‐performance and low‐temperature FE devices and pave the way for reliable integration of hafnia‐based memories into advanced semiconductor architectures.