臺灣博碩士論文加值系統

表面聲波元件是在壓電基板上利用聲電換能原理的特性，做各種訊號的處理。目前通訊元件有朝著高頻化的發展趨勢，而高頻表面聲波元件需要具有高波速，高機電耦合係數，低插入損失等特性，經由壓電薄膜與不同基底材料或高聲速薄膜材料所組成之表面聲波元件可以提高表面聲波元件操作頻率以及增加機電耦合係數，因此在講求輕薄短小的行動通訊產品中已被大量使用。
本研究是使用射頻磁控濺鍍法沉積氧化鋅(ZnO)壓電薄膜於玻璃基板上，並製作交指叉換能器(IDT)在ZnO/Glass上，再利用電子束蒸鍍法沉積氧化鋁(Al2O3)薄膜在IDT/ZnO/Glass上，藉由增加氧化鋁(Al2O3)薄膜的厚度來觀察表面聲波元件頻率響應變化。研究結果顯示在Al2O3/IDT/ZnO/Glass上中心頻率提升到286.125 MHz，波速也提升了26.8 %，證實以電子束蒸鍍法成長高波速Al2O3薄膜可以提升表面聲波元件波速，降低成本並縮短製程時間，將來可以提供作為高頻表面聲波元件之製作。

Now communication elements are developing towards high frequency. Surface acoustic wave (SAW) devices required velocity, high electromechanical coupling coefficient and low insertion loss. SAW devices composed of the piezoelectric thin film and different substrate materials or buffer layers can improve the operating frequency of SAW devices and the electromechanical coupling coefficient. Consequently, SAW devices have been widely applied in mobile communication due to their small size and light weight.
In this study ZnO piezoelectric thin film was deposited on glass substrate by RF magnetron sputtering. Interdigital transducer (IDT) was fabricated on ZnO/Glass, then electron beam evaporation was used to deposit Al2O3 thin film on IDT/ZnO/Glass, the frequency responses of SAW devices by increasing thickness of Al2O3 thin film were studied. The center frequency of Al2O3/IDT/ZnO/Glass has been improved to 286.125 MHz, and the phase velocity has been increased 26.8 %. The electron beam evaporation to develop Al2O3 thin film with high velocity of SAW wave has promoted SAW velocity, lower the cost and shorter the time of Al2O3 growth. The method is sure of producing high frequency SAW devices.

致謝 I
摘要 II
Abstract III
目錄 IV
圖目錄 VII
表目錄 XI
第一章 緒論 1
1-1 研究背景 1
1-2 研究動機 2
第二章 基本理論與文獻回顧 4
2-1 材料基本介紹 4
2-1.1 玻璃基板(Eagle 2000)的特性 4
2-1.2 氧化鋅(ZnO)結構與特性 4
2-1.3 氧化鋁(Al2O3)的結構與特性 5
2-2 壓電特性與表面聲波原理 7
2-2.1 正壓電效應 7
2-2.2 逆壓電效應 8
2-2.3 表面聲波原理 8
2-3 薄膜製作技術 9
2-3.1 電子束蒸鍍法 10
2-3.2 電子束蒸鍍法之原理 11
2-3.3 電子束蒸鍍法之優缺點 12
2-3.4 射頻磁控濺鍍法之原理 12
2-4表面聲波元件 17
2-5 光罩圖形 21
第三章 實驗製程與量測 22
3-1 實驗流程圖 22
3-2 基板準備 23
3-2.1 Eagle 2000玻璃基板 23
3-3 製備氧化鋅(ZnO)薄膜 24
3-3.1 射頻磁控濺鍍氧化鋅(ZnO)薄膜 24
3-4 製備不同厚度氧化鋁(Al2O3)薄膜 24
3-4.1 電子束蒸鍍氧化鋁(Al2O3)薄膜 24
3-5 薄膜物性量測 25
3-5.1 X-ray繞射儀 25
3-5.2 α-step表面紋理分析儀 26
3-5.3 原子力顯微鏡(AFM) 26
3-5.4 掃描式電子顯微鏡 27
3-6 表面聲波元件製作 27
3-6.1 Al2O3/IDT/ZnO/Glass表面聲波元件製作 27
3-6.2表面聲波特性量測 29
第四章 結果與討論 30
4-1 ZnO薄膜分析 30
4-1.1 ZnO/Glass薄膜物性分析 30
4-2 Al2O3薄膜分析 31
4-2.1 Al2O3薄膜沉積參數分析 31
4-2.2 Al2O3薄膜物性分析 32
4-3表面聲波特性量測 33
4-3.1 IDT/ZnO/Glass結構之頻率響應 33
4-3.2 Al2O3薄膜厚度對於表面聲波元件頻率響應之比較 33
4-3.3 Al2O3薄膜厚度對於表面聲波元件機電耦合係數之比較 34
4-3.4 Al2O3薄膜厚度對於表面聲波元件頻率溫度係數之比較 35
第五章 結論與未來展望 36
5-1 結論 36
5-2 未來展望 37
參考文獻 38

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