随着人类社会对移动数据的需求日益增长，存储器作为一种高速发展的信息社会中的核心一环，面临着前所未有的挑战和考验。铁电存储器由于具有容量大、速度快，功耗低等优点，在新型存储器中具有较大的优势。近年来，在掺杂氧化铪薄膜中发现了铁电性的存在。这一发现解决了铁电存储器的可缩小性及CMOS工艺兼容性的问题，引起了学术界和工业界的广泛关注。其中，锆掺杂氧化铪材料由于有着较大的掺杂范围、较高的铁电性表现和良好的可制备性，被认为是可应用于新一代铁电存储器的较为优秀的薄膜材料。在存储器的性能中，介电特性是较为重要的性能参数。介电特性决定了铁电电容的充放电时间常数，同时铁电薄膜的介电性能是表征动态效应、压电效应和电致伸缩效应的关键因素。因此研究介电特性对于优化铁电存储器的速度特性具有重要的意义。在铁电HZO薄膜中，由于电极与铁电铪锆氧层间存在由中间氧化物以及不规则的微观电极表面所带来的界面层。这一非理想的界面层中存在额外的介电弛豫，在铁电HZO薄膜体系中对介电特性具有不可忽略的影响。而由于界面层本身的不规则性和复杂性，对于界面层对铁电介电特性的研究目前仍然有限。本文重点针对HZO与电极间的界面层对介电性能的调控作用展开研究。总结优化了Zr掺杂HfO2（HZO）薄膜样品的制备流程。通过实验制备得到了三种电极（W、TiN、Pt）的HZO薄膜器件。随后对制备得到的器件进行了XRD衍射；AFM、PFM微观形貌检测；I-V、C-V测试等小信号电学测试；电滞回线与铁电性的比较等一系列性能测试。本文测量了室温下不同电极HZO薄膜阻抗的频率响应，通过转换阻抗频谱得到的阻抗Nuquist图与TEM观测的样品结构，分析证明了界面层引入的非理想电容成分的存在。随后，本文针对这一非理想电容，建立了含恒相位元件的阻抗模型。通过优化仿真分析的拟合迭代算法，给出了室温下提取的阻抗参数表，针对不同的电极参数进行了分析比较。解释了界面层的阻抗贡献。在此基础上，本文设计了可用于加温介电测试的测试台，通过实验给出了在不同温度下的W电极、TiN电极、Pt电极HZO薄膜器件的介电频谱，直观表征了介电性能的变化。通过介电频谱中与阻抗参数的提取，反映了界面层在加温状态下的变化，并对其原因从物理本质角度展开了分析探讨。通过整理不同温度下的介电频谱比较，揭示了界面层对HZO薄膜器件介电特性的调控作用，拓展了对铁电HZO阻抗频响特性的研究。
Memory is facing unprecedented challenges and tests with the in-creasing demand for mobile data in human society. Ferroelectric memory has great advantages in the new type of memory because of its large ca-pacity, fast speed and low power consumption. In recent years, ferroelec-tricity has been found in doped hafnium oxide films. This discovery has solved the problems of the miniaturization of ferroelectric memory and the compatibility of CMOS technology, which attracts extensive attention of academia and industry. Among them, the ferroelectric hafnium zirconium oxide materials formed by zirconia doped hafnium oxide are considered to be excellent thin film materials for the new generation of ferroelectric memory due to their large doping range, high ferroelectric performance and favorable preparation ability. Dielectric properties are important perfor-mance parameters in the performance of memory. The dielectric properties determine the charge discharge time constant of ferroelectric capacitor, while the dielectric properties of ferroelectric film are the key factors to characterize the dynamic effect, piezoelectric effect and electro-strictive effect. Therefore, the study of dielectric properties is of great significance to optimize the speed characteristics of ferroelectric memory.There exists an interface layer between the electrode and the ferroe-lectric hafnium zirconium oxide layer in the ferroelectric HZO thin film. It is caused by the intermediate oxide and the irregular micro-electrode sur-face. The interface has an important effect on the dielectric properties of the ferroelectric HZO film system caused by the additional dielectric re-laxation in it. However, due to the irregularity and complexity of the in-terface layer, the research on the ferroelectric properties of the interface layer is still limited.In this paper, the effect of interface between HZO and electrode on dielectric properties is studied. The preparation process of Zr doped HfO2 (HZO) thin films was optimized. HZO thin film devices with three kinds of electrodes (W, TiN, Pt) were prepared. A series of performance tests were carried out for the samples such as XRD diffraction, AFM, PFM micrograph detection, I-V, C-V test and hysteresis loop test.In this paper, the impedance frequency response of HZO thin films with different electrodes at room temperature is measured. The Nuquist diagram of the impedance obtained by converting the impedance spectrum based on the structure observed by TEM were used to analyze and prove the existence of the non-ideal capacitance component brought by the interface. An impedance model with constant phase element was established in order to analyze the impedance response of the interface. Impedance parameters at room temperature were extracted and analyzed based on the optimization of the iterative algorithm of impedance simulation. The impedance contri-bution of the interface was well explained.On this basis, this paper designed a test-bed used for heating dielectric test. The dielectric spectrums of HZO devices with W, TiN, Pt electrodes at elevated temperatures were given in this paper, which directly characterized the change of dielectric properties. The changes of the polarization mech-anism and the lattice vibration in the interface at elevated temperatures were reflected and analyzed through the extraction of dielectric spectrum and impedance parameters. The interface regulation on the dielectric properties of HZO thin film devices was revealed, and the research on the impedance frequency response characteristics of ferroelectric HZO was expanded.
