本實驗設計了具有抑制雜散響應、低插入損耗和高帶外抑制特性的表面聲波(SAW)濾波器；採用42°Y-cut LiTaO3作為壓電基板，並在基板上以直流磁控濺鍍技術沉積具有傾斜角結構的指叉式(IDT)電極。由於鋁(Al)金屬材料具有高導電性和低密度等優點，因此本實驗選擇鋁金屬作為電極，以降低信號傳輸損耗，減小質量負載效應，並防止波速下降。
本實驗初步採用黃光微影系統研究了不同傾斜角度(0°、3°、5°、7°)的IDT電極對低頻SAW共振器與濾波器的插入損耗(IL)、機電耦合係數(k_eff^2)和品質因子(Q)的影響，並使用網絡分析儀測量低頻SAW濾波器的頻率響應，確定了最佳傾斜角度為5°。隨後，採用電子束微影系統製備具有上述最佳傾斜角度的高頻SAW濾波器。最後的實驗結果表明，本研究所設計製作之高頻SAW濾波器具有中心頻率為2.6 GHz、插入損耗為1.21 dB、k_eff^2值為5.4%、Q值為292.67和帶外抑制為41.04 dB等優異之特性。

In this study, the surface acoustic wave (SAW) filters with suppressed spurious response, low insertion loss, and high out-of-band rejection were developed. A 42°Y-cut LiTaO3 was utilized as the piezoelectric substrate and the interdigital transducer (IDT) electrodes with tilted structures were deposited on the substrate through a DC magnetron sputtering technology. Aluminum (Al) was chosen as the metal material for electrode fabrication due to its advantages of high conductivity and low density compared to other metals, which will result in a reduction of signal transmission loss, a minimization of mass loading effect, and prevent a decrease in wave velocity.
The experiment employed photolithography processes to investigate the influences of different tilt angles of IDTs on the insertion loss (IL), electromechanical coupling coefficient (k_eff^2), and quality factor (Q) of the low-frequency SAW devices. By measuring the frequency responses of low-frequency filters using a network analyzer, the optimum tilt angle was determined to be 5o. Subsequently, the electron beam lithography technology was employed to fabricate high-frequency SAW filters with the optimal tilt angle obtained above. Finally, the experimental results showed that the characteristics of the high-frequency SAW filter designed and manufactured in this research existed a center frequency of 2.6 GHz, a insertion loss of 1.21 dB, a k_eff^2 value of 5.4 %, a Q value of 292.67 and a side band rejection of 41.04 dB, respectively.

中文審定書 i
致謝 ii
摘要 iii
ABSTRACT iv
目錄 v
圖目錄 viii
表目錄 xi
第一章 前言 1
1.1 市場背景與研究動機 1
1.2 表面聲波元件結構 3
1.3 文獻回顧 5
1.4 研究內容 6
第二章 理論分析 7
2.1 壓電效應介紹 7
2.1.1 正、逆壓電效應 9
2.1.2 壓電材料 11
2.2 鉭酸鋰(LT)特性 13
2.3 表面聲波元件理論 15
2.3.1 表面聲波元件之設計 16
2.3.2 表面聲波元件之特性分析 19
2.3.3 表面聲波元件之種類 22
2.4 表面聲波之非理想效應 29
2.5 濾波器原理 31
2.5.1 濾波器效能評估 33
2.6 電子束微影技術 35
2.7 乾式蝕刻技術 38
2.7.1 蝕刻製程與非理想效應 39
2.7.2 感應耦合電漿蝕刻原理 40
第三章 實驗設計 41
3.1 實驗流程設計 41
3.2 SAW元件設計 43
3.2.1 光罩設計 43
3.2.2 改善雜散響應設計 48
3.2.3 共振器設計 50
3.2.4 濾波器設計 52
3.3 基板清洗 55
3.4 黃光微影製程 56
3.5 電極薄膜製作與分析 58
3.5.1 鋁薄膜沉積 58
3.5.2 掃描式電子顯微鏡 (Scanning Electron Microscope, SEM) 60
3.5.3 原子力顯微鏡 (Atomic Force Microscope, AFM) 60
3.5.4 四點探針 (Four point probe) 61
3.6 電子束微影 (ELECTRON BEAM LITHOGRAPHY, EBL) 62
3.7 感應耦合式高密度電漿蝕刻機 (ICP RIE SYSTEM, CHLORINE BASE) 64
3.7 網路分析儀 65
第四章 結果與討論 66
4.1 鋁電極分析 66
4.2 SAW元件之製備 68
4.2.1 AZ厚度 68
4.2.2 PMMA厚度 69
4.2.3 電子束微影劑量分析 71
4.2.4 ICP蝕刻製程 73
4.3 SAW共振器 74
4.4 SAW濾波器 76
4.4.1 1階濾波器 76
4.4.2 高頻1.5階濾波器 82
4.4.3 濾波器最佳參數 84
第五章 結論 86
第六章 未來展望 87
參考文獻 88

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