氮化铝压电薄膜的反应磁控溅射制备与性能表征

发布时间：2018-04-27 07:35

  本文选题：氮化铝 + 压电性　； 参考：《中国科学院研究生院(长春光学精密机械与物理研究所)》2014年博士论文

【摘要】：氮化铝(AlN)薄膜材料作为一种重要的III-V族化合物，具有高声波速、高压电性以及良好的化学稳定性等优点，使得AlN压电薄膜在高频声波谐振器、滤波器、传感技术等领域备受关注。反应磁控溅射可以实现高质量AlN压电薄膜的低温快速生长，在实际应用中被广泛采用。但由于材料性能对工艺参数极为敏感以及压电薄膜性能表征等问题，使得该材料的高质量制备尚未形成标准工艺。本文围绕AlN压电薄膜的反应磁控溅射制备方法及性能表征开展了以下研究： 根据电介质的极化理论，研究了AlN材料晶体结构与其内部极化的关系，分析AlN材料压电性的影响因素。同时，利用固体中的弹性波理论计算了不同偏振态下的声波沿AlN晶体各晶轴传播时的相速度,并得出c-轴取向AlN压电薄膜具有较高的压电性以及高纵波速的结论。 为了获得提高AlN压电薄膜c-轴取向的途径，论文通过Berg模型对反应溅射过程氮气流量与其偏压关系进行了模拟，并预测了靶材的工作状态。通过在硅衬底上制备AlN压电薄膜的系列实验，对影响该材料质量的重要工艺参数进行了深入细致的研究；由以上研究可知，当靶材处于金属态与中毒态的过渡区域时，薄膜既可以获得较好质量，，而且还可以维持一定的生长速率； 借助于X射线衍射技术、扫描电子显微镜、原子力显微镜等手段，建立了可对不同制备条件下AlN压电薄膜的晶体结构与形貌的高准确表征的方法。同时提出了一种新型的、更精准的测试模型，利用该模型和压电响应力显微镜等对AlN薄膜的压电性进行测试和验证。 对不同溅射工艺参数下制备的AlN压电薄膜晶体结构、表面形貌以及表面粗糙度的分析发现，在溅射功率为460W，溅射气压为3.0mTorr，氮气流量比为85%，薄膜生长温度为400℃时，可制备出(002)择优取向的高质量AlN压电薄膜，薄膜(002)晶面摇摆曲线的半高宽(FWHM)优于1.70°；在对本文制备的AlN薄膜的压电性定量分析过程中，利用本文所提模型测得AlN薄膜的纵向压电常数：d33=(4.220.34) pm/V，该数值与已报道方法测得的AlN薄膜的纵向压电常数之间的偏差小于5.7%，从而验证了本模型的合理性与准确性。
[Abstract]:As an important III-V family compound, AlN thin film material has the advantages of high acoustic velocity, high voltage and good chemical stability, which makes AlN piezoelectric film in high frequency acoustic wave resonator, filter, etc. Sensing technology and other fields have attracted much attention. Reactive magnetron sputtering (RMC) can realize the rapid growth of high quality AlN piezoelectric films at low temperature and is widely used in practical applications. However, due to the high sensitivity of material properties to process parameters and the characterization of piezoelectric film properties, the high quality preparation of the material has not yet formed a standard process. In this paper, the preparation and characterization of AlN piezoelectric films by reactive magnetron sputtering have been studied as follows: Based on the polarization theory of dielectric, the relationship between crystal structure and internal polarization of AlN material is studied, and the influencing factors of piezoelectric properties of AlN material are analyzed. At the same time, the phase velocities of acoustic waves propagating along each axis of AlN crystal under different polarization states are calculated by using the elastic wave theory in solids, and the conclusion that c-axially oriented AlN piezoelectric thin films have high piezoelectric properties and high longitudinal wave velocity is obtained. In order to obtain a way to improve the c-axis orientation of AlN piezoelectric films, the relationship between nitrogen flow rate and bias voltage in reactive sputtering process was simulated by Berg model, and the working state of the target was predicted. Through a series of experiments on the preparation of AlN piezoelectric thin films on silicon substrates, the important technological parameters affecting the quality of the material are studied in detail. From the above studies, it is known that when the target material is in the transition region between metal state and toxic state, The film can not only obtain better quality, but also maintain a certain growth rate. By means of X-ray diffraction, scanning electron microscope and atomic force microscope, a method was established to characterize the crystal structure and morphology of AlN piezoelectric films under different preparation conditions. At the same time, a new and more accurate testing model is proposed. The piezoelectric properties of AlN thin films are tested and verified by using the model and piezoelectric response force microscope. The crystal structure, surface morphology and surface roughness of AlN piezoelectric thin films prepared by different sputtering process parameters were analyzed. It was found that when sputtering power was 460 W, sputtering pressure was 3.0 m Torr, nitrogen flow ratio was 85 鈩

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