層狀表面聲波濾波器之分析與製造(Ⅱ)

Abstract

表面聲波元件(Surface Acoustic Wave Device)具有高性能、尺寸小、低成本， 且與IC 製程技術相容等優點，使其在電子工業與通訊系統上佔有很重要的地 位。隨著行動通訊的日新月異及對於高資料傳輸速度的要求，傳統結構的表面聲 波元件因受限於電極線寬與基底材料，已不敷使用，而層狀表面聲波元件能利用 不同結構的搭配來提供多重的優點，以應付日益嚴苛的要求，因此本計畫擬以三 年時間研製先進層狀表面聲波振盪器並建立相關的量測技術。計劃第二年以壓電 層狀晶體波傳理論為基礎，配合格林函數及有效介電常數探討覆膜對表面波傳速 度之影響與相對之頻散效應，並分析與設計層狀表面聲波振盪器之頻率響應，實 驗方面則進行薄膜引致之表面聲波頻散實驗探討與彈性性質反算、測定。

With the development of communication technology, there has been a growing interest in the study of SAW filters based on layered structures. By including a high velocity layer between a piezoelectric layer and a substrate, the surface wave velocity can be increased significantly. This results in an increase of the SAW frequency without decreasing the electrode spacing into the sub-micron region. This three-year project is to study the analysis and fabrication of layered SAW filters by both the theoretical and experimental approaches. At the primary stage of the second year, the formulation based on the matrix method for calculating the dispersion relations of a general piezoelectric layered medium was developed. A general-purpose computer program was written for the subsequent analyses. In addition, the effective permittivity and the phase velocity dispersion of a ZnO/diamond layered half space were calculated. The variations of the phase velocity and the electromechanical coupling coefficient with propagation direction were discussed. These calculated results provide useful guidelines for the design of a layered SAW device.