Local Interlaminar Diffusion Drives Excellent Ferroelectricity and Reliability in Zirconium‐Rich Hafnia‐Based Multilayer Films

Abstract Nanoscale (Hf, Zr)O 2 ferroelectric thin films have attracted considerable attention as silicon‐compatible nonvolatile memory materials owing to their low crystallization temperature and remarkable size scalability. However, their metastable ferroelectric orthorhombic phase, high coercive field, and limited endurance, coupled with the high cost of HfO 2 , hinder practical application. Here, rationally designed zirconium‐rich HfO 2 ‐ZrO 2 multilayer thin films, realized via atomic layer deposition, leverage abundant and low‐cost ZrO 2 to both reduce material cost and stabilize the orthorhombic phase. By combining electrical characterization with atomic‐scale aberration‐corrected scanning transmission electron microscopy, it is revealed that local interfacial interdiffusion occurs within the alternating HfO 2 and ZrO 2 sublayers, concurrently with the coexistence of orthorhombic and tetragonal phases. Both experimental observations and theoretical calculations converge on a field‐driven tetragonal‐to‐orthorhombic transformation in the films, exhibiting robust polarization (2 P r > 50 µC cm −2 ), reduced coercive fields ( E c < 1.2 MV cm −1 ), high dielectric tunability (≈41%), and exceptional endurance (polarization degradation limited to ≈2% after 10 9 cycles). These findings demonstrate that the ZrO 2 sublayer thickness and interlaminar diffusion critically influence phase structure, polarization behavior, and endurance in HfO 2 ‐ZrO 2 multilayers, offering an effective strategy to simultaneously optimize ferroelectric performance and device reliability in fluorite‐structured oxide thin films.