物理化学学报 >> 2022, Vol. 38 >> Issue (5): 2006016.doi: 10.3866/PKU.WHXB202006016

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TiN/HfxZr1-xO2/TiN铁电电容器的原位生长与表征

殷宇豪1,2, 沈阳1, 王虎1, 陈肖1, 邵林3, 华文宇3, 王娟4, 崔义1,*()   

  1. 1 中国科学院苏州纳米技术与纳米仿生研究所,纳米真空互联实验站,江苏 苏州 215123
    2 中国科学技术大学纳米科学与技术学院,合肥 230026
    3 无锡拍字节科技有限公司,江苏 无锡 214028
    4 Department of Physics and Engineering Physics, The University of Tulsa, Tulsa, OK 74104, USA
  • 收稿日期:2020-06-08 录用日期:2020-07-02 发布日期:2020-07-10
  • 通讯作者: 崔义 E-mail:ycui2015@sinano.ac.cn

In Situ Growth and Characterization of TiN/HfxZr1-xO2/TiN Ferroelectric Capacitors

Yuhao Yin1,2, Yang Shen1, Hu Wang1, Xiao Chen1, Lin Shao3, Wenyu Hua3, Juan Wang4, Yi Cui1,*()   

  1. 1 Vacuum Interconnected Nanotech Workstation, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, Suzhou 215123, Jiangsu Province, China
    2 Nano Science and Technology Institute, University of Science and Technology of China, Hefei 230026, China
    3 Wuxi Petabyte Technology Co. Ltd., Wuxi 214028, Jiangsu Province, China
    4 Department of Physics and Engineering Physics, The University of Tulsa, Tulsa, OK 74104, USA
  • Received:2020-06-08 Accepted:2020-07-02 Published:2020-07-10
  • Contact: Yi Cui E-mail:ycui2015@sinano.ac.cn
  • About author:Yi Cui, Email: ycui2015@sinano.ac.cn; Tel.: +86-13913595977

摘要:

HfO2基铁电电容器,特别是TiN/HfxZr1-xO2/TiN金属-绝缘体-金属电容器,由于其良好的稳定性、高性能和互补金属氧化物半导体(CMOS)兼容性,在新一代非易失性存储器中有着广阔的应用前景。由于TiN/HfxZr1-xO2/TiN电容器的电性能与HfxZr1-xO2铁电薄膜与TiN电极层界面质量相关,因此控制TiN/HfxZr1-xO2/TiN异质结构的制备和表征至关重要。本文报道了一种三明治结构:HfxZr1-xO2铁电薄膜夹在两个TiN电极之间的新的制备方法,通过超高真空系统互连的原子层沉积(ALD)和磁控溅射设备实现。原位生长和表征结果表明,ZrO2掺杂浓度和快速热退火温度可以调节TiN/HfxZr1-xO2/TiN异质结的铁电性能,并能很好地被互连系统监控。在该体系中,通过在HfO2中掺杂50% (molar fraction, x) ZrO2并且在600 ℃下快速热退火(RTA),获得了21.5 μC·cm-2的高剩余极化率和1.35 V的低矫顽电压。

关键词: 铁电, 表面, 界面, HfO2, 真空互联, 原位

Abstract:

HfO2-based ferroelectric capacitors, particularly TiN/HfxZr1-xO2/TiN metal insulator metal (MIM) capacitors, have attracted considerable attention as promising candidates in the new generation of nonvolatile memory applications, because of their excellent stability, high performance, and complementary metal oxide semiconductor (CMOS) compatibility. At the electrode interface of TiN/HfxZr1-xO2/TiN MIM ferroelectric devices, the existence of the TiOxNy layer, which was formed during HfxZr1-xO2 film crystallization and TiN oxidization, can affect interface/grain boundary energy, film stress, and conduction band offset at the TiN/HfxZr1-xO2 interface, thereby affecting the ferroelectric device performance. Because the electrical performance of TiN/HfxZr1-xO2/TiN capacitors depends on both the ferroelectric HfxZr1-xO2 thin films and electrode TiN/insulator HfxZr1-xO2 interface, it is essential to control the fabrication of the TiN/HfxZr1-xO2/TiN heterostructure. Herein, we report a new method for preparing HfxZr1-xO2 ferroelectric thin films, sandwiched between TiN electrodes, by atomic layer deposition (ALD) and using ultra high vacuum (UHV) sputtering equipment interconnected with an ultra-high vacuum system. The quasi in situ characterization by transmission electron microscopy (TEM), time-of-flight secondary ion mass spectrometry (ToF-SIMS), and other analytical methods conducted in our study indicates that the surface of the bottom TiN electrode does not contain oxygen. Moreover, a flat signal for impurities at the interface suggests that the superior ferroelectric performance of HfxZr1-xO2-based device is mainly attributed to the pristine HfxZr1-xO2/TiN interface. Furthermore, the ferroelectric properties of TiN/HfxZr1-xO2/TiN heterostructures on silicon can be modulated by varying ZrO2 doping concentration and rapid thermal annealing (RTA) temperature, which can be well monitored and controlled by the interconnected system. We also investigate the ferroelectric properties of TiN/HfxZr1-xO2/TiN capacitors with different ZrO2 doping concentrations (30%–60% (x)) at room temperature by changing the ALD pulsing ratio within the vacuum interconnected system. Three identical 10 nm-thick Hf0.5Zr0.5O2 samples sandwiched between TiN electrodes are annealed in N2 ambient at 400, 450 and 600 ℃ for 5 min to investigate the effect of RTA on device performance. The evolution of P-E hysteresis at different applied voltages and RTA temperatures reveals that the saturation of P-E hysteresis and remanent polarization increase with RTA temperature. This increase is especially evident at low applied voltages such as 1.5 V. A higher remanent polarization of 21.5 μC·cm-2 than the previously reported value and a low coercive voltage of 1.35 V were achieved for the electric field of 3 MV·cm-1 by doping 50% (molar fraction, x) ZrO2 in HfO2 through RTA at 600 ℃ for film crystallization.

Key words: Ferroelectrics, Surface, Interface, HfO2, Vacuum interconnection, In situ

MSC2000: 

  • O649