CMOS-MEMS超音波感測器之設計與製作

Design and fabrication of CMOS-MEMS ultrasonic sensors

陳孟輝(MENG-HUI CHEN)

指導教授 ： 盧向成

國立清華大學/電機資訊學院/電子工程研究所/碩士(2007年)

摘要

我們在這篇論文呈現出以CMOS微加工技術製造在空氣中的電容式感測超音波。因為在空氣中，電容的聲波阻抗(結構阻抗)對於傳輸超音波能量所需要考慮的阻抗匹配來說十分重要，所以薄膜的結構設計是成功量測的主要關鍵，利用CoventorWare軟體，結構的阻抗和震盪位移都可以模擬得來。製作薄膜採用後微加工技術，先做金屬的濕蝕刻，後再做反應性離子蝕刻，完成後的薄膜為一直徑65μm的圓盤，由四根橫樑支撐，上下電極形成的感測電容為35fF。在電容偏壓為10伏特下，感測到的訊號為3.25μV，計算後薄膜受到的正向力為0.69nNt，或是0.1394Pa。

關鍵字

微機電系統 ； 電容式感測 ； 薄膜

並列摘要

We presents a CMOS micromachined capacitive sensor for detection of acoustic pressure transmitted through the air in this thesis. Due to the membrane mechanical impedance (acoustic impedance) is important in impedance match during the transition of ultrasonic energy from air into the membrane, the simulation and design of the membrane structure becomes crucial of successful sensing. By using CoventorWare software, the membrane impedance and harmonic vibrations is simulated. The post micromachining steps of the membrane performed at chip level start with a sacrificial metal etch, followed by a dielectric reactive ion etch. The fabricated device has a suspended plate of 65 μm in diameter with four support beams, producing an initial sensing capacitance of 35 fF. The measured sensor output is 3.25 μV at an electrode bias of 10 V while the corresponding acoustic force and pressure acting on the sensor are 0.69 nN and 0.1394 Pa, respectively.

並列關鍵字

MEMS ； Capacitive sensing ； Membrane

參考文獻

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