本研究目的在於運用微機電製程技術製造應用於水下環境之水下聲響微感測器。感測器主要結構為配合微機電製程裡的面型加工技術所製作出的感測薄膜，並在薄膜的感測面鋪上適當的壓阻材料。其運作原理為利用結構本身具有自然振頻之特性，在接受與結構自然振頻接近的特定頻率聲波時，感測器輸出訊號會產生較高的訊雜比，藉此接收聲波所傳遞之訊號內容。

在製程規劃上共有兩種製程，一種是以SOI晶片為基底的製程，一種則是以六吋單晶矽晶片為基底的製程。其差別在於使薄膜懸浮的方式，SOI晶片製程是以浸泡氫氟酸蝕刻犧牲層使薄膜懸浮，六吋單晶矽製程則是採用背後蝕刻使薄膜懸浮。SOI晶片製程由於浸泡氫氟酸時發生電化學反應使壓阻遭受破壞，而單晶矽晶片製程則透過背後蝕刻深度精準的控制，蝕刻出適當厚度之感測薄膜，成功完成感測器的製程。完成後進行感測器封裝，製作出適合水下環境使用之感測器，最後並經由各式聲學實驗設備探討聲響感測器之特性以作為感測器應用之參考。在空氣與水中的測試，感測器成功量測聲波訊號，其訊號與越接近感測器共振頻率頻響反應越佳之趨勢相符，並量測出感測器薄膜之自然振頻。

This study reports a novel design of a MEMS type underwater acoustic sensor using 6”single-crystalline silicon wafer. At resonant frequent of the membrane structure , a high signal-to-noise ratio is expected by chemical vapor deposition thin layers of silicon nitride and poly-silicon , the sensing membrane and piezo-resistive material are patterned and etched using lithography and dry etching process, respectively. After the gold wire is patterned, the entire back side of the sensing membrane is etched in order to create the cavity by back-side etching. The waterproof of the hydrophone is completed by deposition a thin layer of Parylene polymer material. We have proven that the controlled etching process can create the sensing membrane without difficulties and have successfully made the acoustic sensor.

During sensor testing done in air and water, we can receive the frequency of acoustic
accurately. As the frequency of acoustic wave approaches the natural frequency of the sensor, the better frequency response of the sensor is obtained.

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