Zhong Qilan, Wang Yiwei, Cheng Yan, Gao Zhaomeng, Zheng Yunzhe, Xin Tianjiao, Zheng Yonghui, Huang Rong, Lyu Hangbing
Key Laboratory of Polar Materials and Devices (MOE), Department of Electronics, East China Normal University, 500 Dong-chuan Road, Shanghai 200241, China.
Key Laboratory of Microelectronics Devices and Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, 3 Bei-tu-cheng West Road, Beijing 100029, China.
Micromachines (Basel). 2021 Nov 24;12(12):1436. doi: 10.3390/mi12121436.
Hafnia-based ferroelectric (FE) thin films have received extensive attention in both academia and industry, benefitting from their outstanding scalability and excellent CMOS compatibility. Hafnia-based FE capacitors in particular have the potential to be used in dynamic random-access memory (DRAM) applications. Obtaining fine structure characterization at ultra-high spatial resolution is helpful for device performance optimization. Hence, sample preparation by the focused ion beam (FIB) system is an essential step, especially for in situ biasing experiments in a transmission electron microscope (TEM). In this work, we put forward three tips to improve the success rate of in situ biasing experiments: depositing a carbon protective layer to position the interface, welding the sample on the top of the Cu column of the TEM grid, and cutting the sample into a comb-like shape. By these means, in situ biasing of the FE capacitor was realized in TEM, and electric-field-induced tetragonal (t-) to monoclinic (m-) structure transitions in HfZrO FE film were observed. The improvement of FIB sample preparation technology can greatly enhance the quality of in situ biasing TEM samples, improve the success rate, and extend from capacitor sample preparation to other types.
基于氧化铪的铁电（FE）薄膜因其出色的可扩展性和优异的CMOS兼容性，在学术界和工业界都受到了广泛关注。特别是基于氧化铪的铁电电容器有潜力用于动态随机存取存储器（DRAM）应用。在超高空间分辨率下获得精细的结构表征有助于优化器件性能。因此，通过聚焦离子束（FIB）系统进行样品制备是必不可少的一步，尤其是对于在透射电子显微镜（TEM）中进行的原位偏置实验。在这项工作中，我们提出了三个提高原位偏置实验成功率的技巧：沉积碳保护层以定位界面、将样品焊接在TEM网格的铜柱顶部以及将样品切割成梳状。通过这些方法，在TEM中实现了铁电电容器的原位偏置，并观察到了HfZrO铁电薄膜中电场诱导的四方（t-）到单斜（m-）结构转变。FIB样品制备技术的改进可以大大提高原位偏置TEM样品的质量，提高成功率，并从电容器样品制备扩展到其他类型。
