The Fluctuation Effect of Remnant Polarization in Hf₀.₅Zr₀.₅O₂ Capacitors at Elevated Temperatures

Studying the ferroelectric (FE) polarization behavior and failure mechanism of hafnia-based FE devices at varying temperatures is essential for enhancing the reliability of FE memory under real-working conditions. In this study, we investigated the remnant polarization (Pr) fluctuation during electrical cycling in Hf $_{{0}.{5}}$ Zr $_{{0}.{5}}$ O ₂ (HZO) capacitors at elevated temperatures. The decrease in Pr can be attributed to the formation and thickening of the tetragonal (T-) phase interface layer, which reduces the electric field applied to the orthorhombic (O-) phase layer. The subsequent increase in Pr is caused by oxygen defects and leakage current in the T-phase interface layer, raising the electric field applied to the O-FE layer. Therefore, fluctuations in the electric field applied to the O-FE layer are considered as the primary cause for Pr fluctuation. Our direct characterization of T-layers, defects, and electrical properties offers insights into assessing FE phase stability and oxygen defect evolution in fluorite-type FE materials, guiding strategies to enhance device reliability.