利用電子束蒸鍍在ZnO/Glass上沉積氧化鋁薄膜以改善表面聲波元件之特性

Deposition of Al2O3 thin film on ZnO/Glass by e-beam evaporation to improve properties of the surface acoustic wave devices

盧志軒(Chih-hsuan Lu)

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。

關鍵字

氧化鋅 ； 氧化鋁 ； 表面聲波

並列摘要

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.

並列關鍵字

surface acoustic wave ； Al2O3 ； ZnO

參考文獻

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