表面聲波元件(Surface Acoustic Wave Devices) 為通訊系統中重要的關鍵零組件。為了順應高頻化的趨勢，層狀表面聲波元件已引起各方的興趣。藉由不同基底材料與壓電薄膜所組成之層狀表面聲波元件，可同時具備高波速、高機電耦合係數、低傳輸損失、溫度穩定性高等特性。本研究採用壓電性質優良的氮化鋁(AlN)薄膜來提高波速，並選用Si[100]為基板，研究以此兩種材料所組成的層狀二埠表面聲波元件。
首先以層狀壓電介質之波傳理論為基礎，配合八階波動方程來計算層狀表面聲波元件之頻散關係。利用矩陣法建立層狀壓電介質之波傳理論，據此分析表面聲波元件基底材料之波傳行為。
在第二個部分，本文利用Cross & Schmidt提出的耦合模型(Coupling-of-Modes，COM)，作為分析表面聲波元件之理論依據，進而推導出二埠表面聲波濾波器之傳輸矩陣，模擬二埠表面聲波濾波器頻率響應。
在最後部分，以層狀結構下的波傳特性為基礎，以頻散關係(dispersion relation) 、有效介電常數(effective permittivity)與機電耦合係數等，對表面波聲波速偏移(phase velocity shift)、等效電阻值、等效電容值、衰減係數、相位常數和金屬閘極互耦合係數等進行修正，接著討論各項設計參數，交指叉電極對數、交叉長度、金屬柵欄數目、延遲距離及金屬厚度…等對中心頻率響應之影響，作為元件設計之依據。最後據此設計出以AlN/Si[100]作為壓電基板材料、中心頻率為650MHz的二埠表面聲波濾波器。

In recent years, there has been an increasing interest for high-frequency operation in the surface acoustic wave (SAW) devices of layered structure, which compose of several thin films with varied piezoelectric properties. The layered SAW devices have the merits of high electromechanical coupling coefficient, low insertion loss, high characteristic of temperature stability and thus can support high speed of surface acoustic wave. In this project, we studied the layered surface acoustic wave in the piezoelectric material of single crystal aluminum nitride (AlN) deposited on a Si[100] substrate.
In the first part of this thesis, the dispersion relations for a general piezoelectric layered medium is obtained based on the theory of wave propagation in layered media and the Christoffel’s wave displacement equation. The dispersion relations can be transformed in the matrix form for further numerical calculation. The numerical analysis technique and a general-purpose computer program for a general piezoelectric layered medium was presented.
In the second part, we studied the coupling-of-mode (COM) model of Cross and Schmidt and investigated it’s applicability for analyzing the frequency response of layered SAW filters.
In the last part of this thesis, we demonstrated the bulk properties of the phase velocity shift, the effective resistance, the effective capacitance, the grating mutual-coupling coefficient and the attenuation constant must be adjusted for the layered SAW filters. In order to simulate frequency responses more accurately, we substituted these parameters mentioned above into the COM model and discussed the dependence of these parameters on the number of pairs of IDT, the cross length of the IDT, the delay distance, the number of the grating IDT pairs. Regarding AlN/Si [100 ] as the piezoelectric substrate material, the surface acoustic wave filters of two ports with the centre frequency of 650MHz was proposed.

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