In Situ Study of the Ferroelectric–Antiferroelectric Phase Transition in Hf 1– x Zr x O 2 at Elevated Temperatures up to 600 °C

(HZO) has emerged as a promising candidate for non-volatile memory applications due to its excellent scalability, CMOS compatibility, and low thermal budget. However, its phase stability under elevated temperature conditions remains insufficiently understood. Here, we present a comprehensive study on the temperature-dependent phase behavior of HZO capacitors up to 600 °C. By systematically varying film thickness and composition, we identify the critical conditions under which the ferroelectric-antiferroelectric (FE-AFE) transition emerges. Experimental results reveal that this transition originates from the thermal stabilization of the tetragonal phase, as confirmed by sublattice phase-field simulations. Thinner films and Zr-rich compositions exhibit lower transition temperatures, while Hf-rich compositions maintain ferroelectricity at higher temperatures. Furthermore, the FE-AFE transition is shown to be both reversible and repeatable under thermal cycling. These findings provide key insights for the co-design of materials, processes, devices, and reliability in the development of CMOS-compatible ferroelectric memory under variable thermal environments.