The in-plane strain in the ferroelectric HfxZr1−xO2 (HZO) thin films has been considered to be the global factor behind many process parameters affecting the concentration of metastable polar-orthorhombic phase (O-phase Pca21) formed in the transformation pathway from tetragonal to monoclinic phase. However, the strain is generally effective in crystal phase nucleation and transition with the thermal budget and itself also changes with the thermal budget. The issue of how the O-phase is formed and changed in real time with effect of both thermal budget and in-plane strain has not been clarified, which is critical for engineering the O-phase concentration. Focusing on this issue, this work demonstrates the co-effect of strain and temperature on phase formation and transition in HZO by employing the synchrotron-based in situ two-dimensional (2D) grazing incidence x-ray diffraction (GIXRD) investigation. HZO thin films with different process parameters exhibit four types of phase transition processes during heating and cooling. Meanwhile, the in-plane strain magnitude and each phase concentration in the films during annealing are extracted. Based on both, the study established a universal temperature-strain phase diagram of HZO films and proposed a kinetic model for optimizing the ferroelectric O-phase formation. The study provides deep insights into O-phase engineering and ferroelectricity optimization in HZO thin films.

中文翻译：

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基于同步加速器的原位 2D GIXRD 研究的 HfxZr1−xO2 薄膜亚稳温度-应变相图


铁电 HfxZr1−xO2 （HZO） 薄膜中的面内应变被认为是影响亚稳态极正交相 （O 相 Pca21） 浓度的许多工艺参数浓度的全局因素，这些参数在从四方相到单斜相的转变途径中形成。然而，应变通常在晶相成核和随热预算的转变中有效，并且其本身也随热预算而变化。O 相如何根据热预算和面内应变的实际形成和变化的问题尚未阐明，这对于设计 O 相浓度至关重要。针对这个问题，这项工作通过采用基于同步加速器的原位二维 （2D） 掠入射 X 射线衍射 （GIXRD） 研究，证明了应变和温度对 HZO 中相形成和转变的协同影响。具有不同工艺参数的 HZO 薄膜在加热和冷却过程中表现出四种类型的相变过程。同时，提取退火过程中薄膜中的面内应变大小和各相浓度。基于两者，该研究建立了 HZO 薄膜的通用温度-应变相图，并提出了优化铁电 O 相形成的动力学模型。该研究为 HZO 薄膜中的 O 相工程和铁电优化提供了深入的见解。