Atomic visualization of the emergence of orthorhombic phase in Hf 0.5 Zr 0.5 O 2 ferroelectric film with in-situ rapid thermal annealing

作者：Tianjiao Xin, Yonghui Zheng, Yan Cheng, Kai Du, Yiwei Wang, Zhaomeng Gao, Diqing Su, Yunzhe Zheng, Qilan Zhong, Cheng Liu, Rong Huang, Chun‐Gang Duan, Sannian Song, Zhitang Song, Hangbing Lv · 发表于：2022 IEEE Symposium on VLSI Technology and Circuits (VLSI Technology and Circuits) · 年份：2022 · DOI：10.1109/vlsitechnologyandcir46769.2022.9830185 · 被引用次数：16 · 研究领域：Ferroelectric and Negative Capacitance Devices、MXene and MAX Phase Materials、Semiconductor materials and devices

For the first time, the dynamic process of orthorhombic (o-) phase emergence during rapid thermal annealing in polycrystalline Hf0.5Zr0.5O2(HZO) ferroelectric film was directly visualized though in-situ spherical aberration corrected transmission electron microscopy technique. We have the following main observations: (1) o-phase nucleates from centrosymmetric tetragonal (t-) phase at top TiN/HZO interface where the oxygen vacancy (Vo) concentration is rich, identifying that Vo is helpful to lower the free energy of o-phase; (2) o-phase appears in both heating up and cooling down stages. The o-phase formed in the heating stage rapidly transforms into t-phase again as the temperature further increasing, and the one formed in the cooling stage is retained. These findings provide solid evidence on the o-phase origin in fluorite-type ferroelectric materials.