這項研究提出了一種可用於水中的超音波感測的CMOS微電容式感測器。透過CMOS MEMS的技術，可以將感測器和放大器整合在一起。藉由在感測薄膜下方放置感測電路，可有效降低電路的寄生電容，並且節省整體IC的面積。
本研究目的在於提升傳感器接收到超音波的頻率，將結構共振頻和放大器頻寬提升到15 MHz以上，提升頻率將可增加光聲影像的解析度，對於生醫影像將會有大幅度地改善。
此研究運用CMOS微製程製作電容感測器，成功的呈現超音波訊號。感測薄膜大小為42 μm，透過後製程的步驟我們經由2 μm × 2 μm蝕刻孔將金屬層(Metal 3)蝕刻，再用oxide封閉蝕刻孔。四個薄膜構成一個感測單元其電容值為70 fF。水中超音波訊號的共振頻率為15 MHz。
在量測碳纖維三維光聲造影方面，本研究之橫向解析度為362.5 μm，軸向解析度為300.7 μm；在量測頭髮三維光聲造影方面，本研究之橫向解析度為507 μm，軸向解析度為305 μm。

This study presents a CMOS micromachined capacitive ultrasonic sensor that can be used in water. By using CMOS MEMS technology, the sensor can be integrated with the amplifier. By placing sensing circuit beneath the sensor, we can effectively reduce the parasitic capacitance of the circuit and save the sensor area.
Purpose of this study is to increase the ultrasonic frequency of the sensor. We will increase the structural resonance frequency and bandwidth of the amplifier to 15 MHz. Increasing the frequency will enhance the resolution of photoacoustic imaging.
This study shows the measured ultrasonic signals by the capacitive sensors fabricated by post CMOS fabrication. The sensor size is 42 μm. By using post-CMOS process, we etch the metal layer (Metal 3) through the 2 μm × 2 μm etching holes, and then refill the etching holes by silicon dioxide. Four membranes constitute a single sensor. The total capacitance value is 70 fF. The resonance frequency of the ultrasonic signals in water is 15 MHz.
For the 3D photoacoustic imaging of a carbon fiber, the lateral resolution is 362.5 μm, and the axial resolution is 300.7 μm. For the 3D photoacoustic imaging of an hair, the lateral resolution is 507 μm, and the axial resolution is 305 μm.

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