本論文探討如何以懸臂樑共振頻率的變化來量測液體的黏滯度與密度。微結構懸臂樑的致動方式包含壓電片驅動與靜電驅動兩種，壓電片驅動是透過晶片下面的壓電片振動而來，靜電驅動則是在兩電極間施加一隨時間週期性變化的電壓，使得振動元件受到交替的靜電推力而產生振動，電路感測方式有兩種，一種是壓阻式感測，將多晶矽材料的壓阻沉積在微結構的懸臂樑之中，藉由懸臂樑在液體中的振動導致的壓阻變化，轉化為電訊號的變化；另一種是電容式感測，藉由懸臂樑在液體中的振動導致的電容值變化，轉化為電訊號的變化，此變化可得知懸臂樑結構在液體中的共振頻率與品質因素，再利用共振頻率與品質因素來分析得到液體中的黏滯度與密度，未來希望透過增益與相位補償電路來建立振盪迴圈，偵測結構的輸出振頻。
本晶片使用TSMC 2P4M 0.35μm CMOS製程，將靜電驅動式微結構懸臂樑與感測電路整合於單一個晶片上，晶片總面積為3.52 mm×2.7 mm，利用CMOS製程將氧化層及多晶矽層當作振動結構之質量塊，設計兩種不同寬度和厚度的微懸臂樑來比較其感測度，其中較寬的結構可以得到較高的量測品質因素，較高的品質因素可提升量測的精準性。
完成製程後，微懸臂樑結構量測的結果，空氣共振頻率測得為83 kHz，模擬則為113kHz，其誤差原因是製程後導致微懸臂樑厚度變薄，另外在純水溶液之共振頻率為24.65kHz、品質因素為14.94，透過這些量測數值可以間接推得該液體的黏滯度與密度。

In this thesis, we study how to measure the viscosity and density of liquids with the changes in resonant frequency and quality factor of the cantilever beams. The cantilever beams can be driven by piezoelectric or capacitive actuation. Piezoelectric actuator is attached underneath the CMOS chip, while capacitive driving is provided by on-chip electrodes. Two sensing methods are used. The polycrystalline silicon at the anchor of a cantilever beam serves as a piezoresistive sensor to detect the force caused by vibration of the cantilever beam in liquids. Capacitive sensing is also used to detect the vibration of cantilever beams. The viscosity and density are calculated based on the measured resonant frequency and quality factor in liquids. In the future, it is desirable to implement an oscillation loop with the compensation circuits for gain and phase in the aim to measure the resonant frequency shift.
The integrated chip containing the mechanical structure, driving electrode and sensing circuits, is implemented by using the 2P4M 0.35-μm CMOS process. The chip area is 3.52 × 2.7 mm2. Structures are made of silicon dioxide. Sensing performances of designs with different widths and thicknesses are compared. The wider structure can obtain a higher quality factor from the measurement, leading to improved accuracy.
After completion of the post fabrication process, the resonant frequency of one micro-cantilever is measured at 83 kHz in air, as compared to 113 kHz by simulation, which is owing to the reduced thickness from the post fabrication process. The measured resonant frequency in de-ionized water is 24.65 kHz and the quality factor is 14.94. The viscosity and density of the liquid can be calculated from the measured values.

摘要 I
Abstract II
致謝 III
符號解釋 IV
目錄 VI
圖目錄 VIII
表目錄 XI
第1章 緒論 12
1-1 前言 12
1-2 文獻回顧 14
1-3 研究動機 16
1-4 晶片系統架構 17
第2章 微懸臂樑結構設計與製作 19
2-1 液體理論分析 19
2-2 液體黏滯度與密度計算 22
2-3 結構設計與模擬 23
2-4 驅動方式與感測電路 30
2-5 後製程設計 33
第3章 量測與討論 35
3-1 後製程量測 35
3-2 結構模態量測 38
3-3 結構在真空中自然振頻與空氣中共振頻率比較 41
3-4 液體量測 42
3-5 不同寬度的微懸臂樑在液體量測之品質因素比較 48
3-6 液體黏滯度與密度之計算 49
3-7 量測平台架設 53
3-8 量測與製程討論 56
第4章 結論與未來 58
第5章 參考文獻 59
第6章 附錄 62

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