物理化学学报2022，Vol.38Issue(5)：89-96,8.DOI:10.3866/PKU.WHXB202006016
TiN/HfxZr1-xO2/TiN铁电电容器的原位生长与表征
In Situ Growth and Characterization of TiN/HfxZr1-xO2/TiN Ferroelectric Capacitors
摘要
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.关键词
铁电/表面/界面/HfO2/真空互联/原位Key words
Ferroelectrics/Surface/Interface/HfO2/Vacuum interconnection/In situ分类
化学化工引用本文复制引用
殷宇豪,沈阳,王虎,陈肖,邵林,华文宇,王娟,崔义..TiN/HfxZr1-xO2/TiN铁电电容器的原位生长与表征[J].物理化学学报,2022,38(5):89-96,8.基金项目
The authors are grateful for the support from Nano Fabrication Facility and Platform for Characterization&Test from Suzhou Institute of Nano-Tech and Nano-Bionics,CAS.Also thanks to the help from Prof.Rongxin Wang for fruitful discussion,Ms.Zhiyun Li with XPS experiments in Nano-X from Suzhou Institute of Nano-Tech and Nano-Bionics,CAS. （）
