以氮化鋁為壓電層比較不同基板上SAW元件特性

本研究以低溫沉積法將氮化鋁薄膜分別沉積至 Si 基板以及 Sapphire 基板上並且分別以二硫化鉬(????????????2)、二硫化鎢(????????2)薄膜當作緩衝層(buffer layer)並在上面製作表面聲波元件(surface acoustic wave, SAW)。本研究分別沉積至矽(Si)基板、藍寶石(Sapphire)基板完成了在 MoS2/Si、WS2/Sapphire SAW 之元件，在此研究中以沒有二維材料當作緩衝層之 SAW 元件當作對照組，探討其個別特性，先透過 XRD、原子力顯微鏡 AFM 了解沉積在基板上的薄膜品質，再透過網路分析儀測得 SAW 元件中心頻率(frequency)、插入損耗(insertion loss)、旁波辦 (sidelobe)等元件特性。一開始，利用低溫沉積法將氮化鋁薄膜沉積至市售之 MoS2/Si、 WS2/Sapphire 基板，除了以上兩塊有二維材料基板外也會利用相同沉積條件沉積在沒有二維材料的 Si 基板以及 Sapphire 基板上。沉積好基板透過 XRD、AFM 儀器量測去確認沉積之氮化鋁薄膜品質。之後透過微影蝕刻製程成功地在四片基板上做出表面聲波元件，並利用 OM 確認基板上的元件沒有過度蝕刻，再來透過網路分析儀確認元件的中心頻率以及插入損耗。發現不同基板上元件的中心頻率不僅不一樣也發現損耗有所不同。由以上各種實驗結論數據顯示，本論文所研製而成的四個表面聲波元件皆成功擁有表面聲波元件特性，也結合新穎的二維材料與簡單製程 SAW。以本實驗四個不同基板元件的量測結果顯示有二維材料當作緩衝層之基板可以擁有較明顯的 SAW 元件濾波特性的呈現，並確認 SAW 可以與矽製程做結合。展現著元件在未來高頻的應用上的潛力。

關鍵字

氮化鋁薄膜；二硫化鉬；二硫化鎢；表面聲波元件

並列摘要

In this study, surface acoustic wave (SAW) devices were fabricated on Al/AlN/????????????2/Si、Al/AlN/????????2/Sapphire respectively. AlN thin film were deposited on Si and Sapphire substrates using low temperature sputtering method. In addition, molybdenum disulfide and tungsten disulfide films were used as buffer layers for Si and Sapphire, respectively.The SAW devices without two-dimensional material as a buffer layer was used as a basic control standard to discuss the characteristics. Firstly, the quality of the AlN films deposited on the substrates are investigated by XRD and AFM, and the center frequency and insertion loss are measured using a network analyzer. The fabrication begin with Al/AlN thin films deposited and etched on commercially MoS2/Si and WS2/Sapphire substrates by lowtemperature sputtering. In addition to the above two substrates on 2D materials, the same deposition conditions were used to deposit AlN film on Si and sapphire substrates without 2D materials. After the deposited substrate is measured by XRD and AFM, the quality of the deposited film is examined. The surface acoustic wave devices were successfully fabricated on four substrates using photo lithography.OM was used to observe whether the device on the substrates were over-etched or not, and the center frequency and insertion loss of the components were measured by a network analyzer. It was found that the center frequencies as well as the insertion losss of the SAW devices prepared on different substrates were various. According to the above mentioned experimental results, the four surface acoustic wave devices developed in this work all reveal the characteristics of surface acoustic wave devices. Using the combination of novel twodimensional materials and simple fabricated process SAW, the results demonstrate the feasibility the employment of two-dimensional materials as buffer layers. The saw devices exhibit less noise, and in addition, the fabrication process compatible with silicon process. It reveals he future potential applications of the SAW devices.