利用電子束蒸鍍在石英與鈮酸鋰基板上沉積氧化鋁薄膜以改善表面聲波元件之特性

Depositing Al2O3 thin film on Quartz and LiNbO3 substrates by e-beam evaporation to improve properties of the SAW devices

林書正(Shu-Jheng Lin)

指導教授 ： 吳慕鄉

大同大學/電機資訊學院/光電工程研究所/碩士(2010年)

摘要

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須具有高波速，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。
本研究在石英與鈮酸鋰壓電基板上製作指叉狀換能器(IDT)完成後，使用電子束蒸鍍法(electron beam evaporation)成長氧化鋁(Al2O3)薄膜在石英與鈮酸鋰基板上，比較在不同厚度的氧化鋁薄膜之表面聲波元件頻率響應變化。研究結果顯示在IDT/Quartz及IDT/LiNbO3上波速成功地隨著氧化鋁薄膜厚度增加時則波速會由1.75 %提升至最大3.17 %與1.65 %提升至最大5.97 %。證實以電子束蒸鍍法成長高波速氧化鋁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。

關鍵字

鈮酸鋰 ； 石英 ； 氧化鋁

並列摘要

Now communication elements are developing towards high frequency. SAW devices must have high 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 IDT is fabricated on Quartz and LiNbO3 piezoelectric substrate. We employ electron beam evaporation to deposit Al2O3 thin film on Quartz and LiNbO3 SAW device over the IDT regions. As compared with different thicknesses of Al2O3 thin film which frequency responses of SAW devices. Successfully, the phase velocity of IDT/Quartz and IDT/LiNbO3 with Al2O3 thin film increased has been improved from 1.75 % to 3.17 % and 1.65 % to 5.97 %. The electron beam evaporation to develop Al2O3 thin film with high velocity of wave has been proved to promote SAW velocity, lower the cost and shorten the time of production. The method is sure of producing high frequency SAW devices.

並列關鍵字

LiNbO3 ； Quartz ； aluminum oxide

參考文獻

21. 郭奕麟, “利用電子束蒸鍍在石英基板上沉積氧化鋁薄膜以改善表面聲波元件之特性”，私立大同大學光電工程所碩士論文, 2008.

20. 許歷綸, “利用電子束蒸鍍在鈮酸鋰基板上沉積氧化鋁薄膜以改善表 面聲波元件之特性”,私立大同大學光電工程所碩士論文, 2007.

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