【作者】 马靖；

【导师】 陈希明；

【作者基本信息】 天津理工大学 ， 光学工程， 2005， 硕士

【摘要】 声表面波器件(Surface Acoustic Wave Device)是通讯系统中重要的器件之一。由于目前通讯器件朝着高频化发展，优良的高频声表面波器件必须具有高声速、高机电耦合系数、低传播损耗、高温度稳定性等特性。通过在压电材料与衬底之间加入高声速的金刚石膜层，可以提高声表面波传播速度，使声表面声波器件在不改变叉指换能器(IDT)线宽条件下，提高中心频率，以满足通信系统的高频需求。本研究采用金刚石为基片来提高声表面波速度，并选用压电性能优良的氧化锌(ZnO)薄膜压电材料，对ZnO／IDT／金刚石多层膜结构的声表面波器件分析和研制。主要完成了以下几方面工作：1．理论模型研究以多层结构的波传播特性为基础计算出声表面波传播速度和机电耦合系数，应用耦合模型(coupling of modes)理论，进一步模拟出多层结构声表面波滤波器的频率响应，优化设计多层结构基片和叉指换能器结构，编制了模拟程序软件。2．高频声表面波滤波器的多层结构基片及器件的设计和制备根据理论分析设计出的高频声表面波滤波器的多层结构基片和叉指换能器结构，采用热丝化学气相沉积(HFCVD)技术在硅衬底上沉积了满足高频声表面波器件中金刚石晶体结构、厚度和表面粗糙度要求的金刚石膜。同时采用射频磁控溅射方法制备了C轴定向的氧化锌压电薄膜，结合光刻工艺实际制作出ZnO／IDT／金刚石／Si的多层结构声表面波滤波器，成功的将中心频率提高至1.5GHz。最后，利用网络分析仪测量的多层结构声表面波滤波器的输出结果，与压电单晶结构的输出特性进行了对比，中心频率是普通压电单晶的3倍，并满足高频需求：同时，实际输出特性与仿真的输出结果作了对比，确定理论模拟对于多层结构声表面波滤波器的适用性。3．为了进一步扩展声表面波器件的应用领域，还对无线、无源声表面波传感器进行了初步探讨，进行了参数设计，器件的制作及测量方法的研究工作。综上所述，本论文针对ZnO／IDT／金刚石／Si多层结构高频声表面波滤波器提供了完整的理论、制备和结果测量。实验结果验证了本文研制的多层结构声表面波滤波器能够提高传播速度、中心频率，降低损耗，满足未来高频需求。另外，对声表面波器件的另一种应用——声表面波传感器进行了初步研究。本文的创新工作如下：1．自行开发、研制多层结构声表面波器件模拟程序、为多层高频声表面波滤波器优化基片结构和叉指换能器结构提供了理论依据。2．研究了高声速金刚石膜及其CVD沉积工艺。提出了包括Si基片预处理、灯丝碳化、金刚石形核和生长在内的全部工艺，经检验能满足高频声表面波滤波器的要求。3．提出了多层膜厚度的精确测量新方法。在无需已知相对介电常数(ε)的情况下得到比较精确的厚度值，而且测量精度能达到19nm左右。4．研制了中心频率1.5GHz的高频声表面波滤波器。更多还原

【Abstract】 Surface acoustic wave devices (SAWD) are one of the most necessary devices in communication system. In recent years, there has been an increasing interest in developing surface acoustic wave devices operating at high frequencies. In order to obtain high-frequency SAW devices, a substrate material with high acoustic velocity is desired. By depositing a piezoelectric film on top of a high acoustic velocity substrate-diamond. the purpose of high frequency can be achieved without the fabrication of fine electrodes of IDT.Diamond substrate is an attractive material because of its high acoustic velocity. And ZnO thin film has been widely used for layered SAW devices due to its high piezoelectric character. Therefor(?), ZnO/IDT/diamond which is a promising multilayered structure for high-frequency SAW device is analysis and fabricated.Firstly, based on the SAW properties, surface wave velocity and coupling coefficient are measured and discussed. Then the frequency response of SAW devices is simulated by the coupling-of-mode (COM) model. Combing these two methods, we can thus design and analyze the multilayered SAW devices included with substrate and IDT structure.Secondly, based on the design and analyze of substrate and IDT structure of the multilayered SAW devices, we have deposited the diamond films whose thickness, structure and surface roughness are satisfied to SAW filter using hot-filament chemical vapor deposition (HFCVD) reactor on Silicon were investigated in this paper. And c-orient ZnO piezoelectric material are deposited successfully using RF magnetic control sputtering. Then ZnO/IDT/diamond/Si multilayered structures SAW filters are fabricated in this thesis. We found that the center frequency increased to 1.5GHz. Additionally, I present a new method to measure thickness of multilayered films which can measure thickness up to 19nm accurately.Finally, frequency responses results using network analyzer are three times compared with one of normal piezoelectric crystal. Compared with modified simulation results, results show that modified simulation are agreement with experimental frequency responses.On the other hand, in order to expand SAW application, wireless and passive surface acoustic wave sensor included with parameter design, fabrication and measurement method are studied primarily.The innovation research results of this paper are following:1. I program about simula(?)on, I can thus design and analyze the multilayered SAW devices included with substrate and IDT structure.2. 1 do research about high acoustic velocity diamond films and the CVD process. I present entire process included with carbonizing filament, pretreating Silicon substrate, nucleus and growth of diamond films. The sample adapt to high frequency SAW filter.3. I present a new method to measure thickness of multilayered films which can measure thickness up to 19nm accurately.4. ZnO/IDT/diamond/Si multilayered structures SAW filters are fabricated in this thesis.更多还原