本研究運用CMOS MEMS技術設計出微電容式超音波感測器，特色是整合電路和感測器於單一晶片，能有效的降低寄生電容，研究所使用的製程為TSMC 0.18 μm 1P6M CMOS Process，選用特有MIM電容作為感測結構的設計，選擇厚度較薄的金屬層(CTM層)作為犧牲層，為了降低空腔的厚度獲得更高的感測電容值；透過濕蝕刻成功的釋放結構，並藉由2微米的二氧化矽的封裝，感測器成功在水中進行超音波量測，實驗結果顯示直徑的80 μm圓形結構共振頻率達5.8 MHz，感測頻寬為2.2 MHz，感測度為249.1 (mV_pp)⁄(MPa/V)，其各種特性均比以前使用TSMC 0.35 μm 2P4M CMOS Process 製作的感測器較好。

This work presents a capacitive ultrasonic sensor chip fabricated by the CMOS-MEMS technology. The unique feature of this work is integrating the circuit and the sensor on the same chip, which can efficiently reduce the parasitic capacitance. This work used the TSMC 0.18-μm 1P6M CMOS process, for fabrication, in which the MIM capacitors are used as our sensing structure. The thin CTM layer is used as the sacrificial layer in order to reduce the air cavity thickness for achieving higher sensitivity than our previous work.
The structure is successfully released by wet etching and sealed by 2-μm silicon dioxide. The fabricated capacitive ultrasonic sensor is tested in water. The microstructure has an 80-μm diameter. The measured resonant frequency, band width and sensitivity are 5.8 MHz, 2.2 MHz, and 249.1 (mV_pp)⁄(MPa/V), respectively, which are better than the previous devices fabricated in the TSMC 0.35-μm 2P4M CMOS process .

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