Effect of a ZrO2 Seed Layer on the Antiferroelectric Polarization Behavior and Stability of Zr-Rich ZrHfO x Films

Abstract

Antiferroelectric Zr-rich ZrHfOx thin films are promising for advanced memory applications, yet their phase stability and reliability remain challenging. In this work, the effects of ZrO2 seed layers with different thicknesses [1 nm ZrO2/ZrHfOx (1Z-ZrHfOx), 2 nm ZrO2/ZrHfOx (2Z-ZrHfOx), and 3 nm ZrO2/ZrHfOx (3Z-ZrHfOx)] on the phase composition, defect characteristics, endurance, and temperature-dependent properties of ZrHfOx antiferroelectric films are systematically investigated. Compared with the control sample, the introduction of a ZrO2 seed layer effectively increases the tetragonal (t-) phase fraction while suppressing the orthorhombic (o-) and monoclinic (m-) phases. Notably, 2Z-ZrHfOx induces the most pronounced phase modulation, increasing the t-phase fraction from 47.4% to 60.2% and significantly reducing the m-phase content. In addition, ZrO2 seed layer assisted growth results in a reduced concentration of the oxygen-vacancy-related component, indicating improved crystalline quality and suppressed defect formation. Furthermore, all the antiferroelectric devices maintain intact switching characteristics without breakdown up to 1012 cycles, while the evolution of polarization parameters during cycling is strongly dependent on seed layer thickness. Moreover, temperature-dependent measurements reveal that the ZrO2 seed layer offers limited inhibition against thermally induced degradation. These results demonstrate that ZrO2 seed layer thickness engineering provides an effective route to simultaneously enhance endurance in ZrHfOx-based antiferroelectric memory devices.