Analysis And Fabrication Of Multilayered Structure High Frequency SAW Device

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.