本研究利用TSMC 0.35μm 2-Poly 4-Metal CMOS-MEMS標準製程與氮化鈦(TiN-C)後製程開發微機電電容式超聲波換能器(CMUT)，CMUT元件具有可相容於標準CMOS製程之單晶片整合特性，因此本研究利用CMOS製程中之BEOL層設計結構並結合TiN-C後製程以及薄膜陣列設計提升元件性能。其中TiN-C後製程藉由鋁蝕刻將平行電容板感測間隙微縮至0.4μm，有效降低元件運動阻抗，除了降低元件操作偏壓外，亦增加元件之感測靈敏度。本研究開發之CMUT on CMOS TiN-C CMUT元件，其開發重點著重在將元件與介面電路進行單晶片之機電整合，目標將每一個感測像素對應之介面電路直接布局在元件機械結構的正下方，藉此達到更緊湊的二維感測器陣列系統設計，本研究成功展示之CMUT on CMOS的元件，藉由降低雜散電容對系統的影響，得以進一步將元件操作的直流偏壓降低，在僅2.5V直流偏壓條件下，得到4.78mV/kPa元件感測靈敏度，並在探頭到元件距離60mm下測得中心頻率2MHz，6dB比例頻寬89%，期待未來元件不僅能適用於生醫造影等應用外，也可朝水中通訊定位等應用發展。

This work utilized the TSMC 0.35μm 2-Poly 4-Metal CMOS-MEMS standard process with TiN-C post process to develop Capacitive Micromachined Ultrasonic Transducers (CMUT). The key characteristic of CMUT devices is single-chip integration with circuit. The CMUT is realized by the back-end-of-line layers while combining the TiN-C post process to minimize the sensing gap between electrodes. TiN-C post process utilizes Al etching which defines 0.4μm gap reducing the motional impedance and thus enhancing the performance. This reduces the required bias voltage and increases the sensitivity. This work emphasizes on the single chip integration between MEMS and IC. CMUT on CMOS design was achieved by placing the corresponding interface circuit of each sensing CMUT pixel under its MEMS structure to simplify the routings while lowering the parasitic capacitance effect. We successfully demonstrated a CMUT on CMOS device that reduced the DC bias voltage to 2.5V while having a reception sensitivity of 4.78mV/kPa. Under an immersion depth of 60mm, the device was characterized having a center frequency of 2MHz with a 6dB bandwidth of approx. 89%. We expect that in the future the device can be applied to ultrasound imaging applications while exploring the possibility of immersion data communication applications.

摘要---i
目錄---iii
圖目錄---vi
表目錄---xii
第一章 前言---1
1-1 研究動機與背景---1
1-2 文獻回顧---4
1-3 文章架構---9
第二章 元件設計分析---12
2-1 CMOS-MEMS電容式超聲波傳感器---12
2-1-1 CMOS-MEMS技術---13
2-1-2 電容式感測與壓電式感測之比較---14
2-1-3 電容式感測機制之原理---16
2-2 薄膜共振器之原理與分析---19
2-2-1 等效電路系統---19
2-2-2 薄膜式共振器之理論分析---21
2-3 CMUT感測器設計---25
2-3-1 設計概念---25
2-3-2 元件運動阻抗最佳化之設計---27
2-3-3 CMOS金屬薄膜釋放後製程比較---29
2-3-4 CMUT on CMOS元件設計---31
2-3-5 CMUT on CMOS元件理論分析---36
2-3-6 CMUT on CMOS元件設計模擬---40
第三章 CMUT介面電路設計---42
3-1 CMUT on CMOS介面電路設計---42
3-2 CMUT on CMOS 介面電路性能驗證---48
3-2-1 CMUT介面電路量測架設---48
3-2-2 CMUT介面電路量測結果---49
3-2-3 系統雜訊量測---51
第四章 後製程步驟與結果---53
4-1 TiN-C 後蝕刻製程測試---54
4-2 TiN-C CMOS-MEMS CMUT後製程---56
4-3 元件封裝後製程---62
4-4 後製程測試CMUT元件後製程結果---64
4-5 CMUT on CMOS元件後製程結果---69
4-5-1 CMUT on CMOS元件光學顯微鏡影像圖---69
4-5-2 CMUT on CMOS元件電子顯微鏡影像圖---75
第五章 TiN-C CMUT量測與討論---78
5-1 CMUT on CMOS元件電信號量測---78
5-1-1 CMUT on CMOS元件電信號量測架設---79
5-1-2 CMUT on CMOS元件電信號量測結果---80
5-2 CMUT on CMOS元件超聲波接收性能量測---82
5-2-1 CMUT on CMOS元件超聲波接收實驗量測架設---82
5-2-2 CMUT on CMOS元件超聲波接收實驗量測結果---85
5-3 CMUT on CMOS元件製程結果分析---88
第六章 結語---93
附錄 測試用CMUT性能量測結果---96
A-1 測試用CMUT機械訊號量測---96
A-1-1測試用CMUT元件電信號量測架設 96
A-1-2 測試用CMUT元件電信號量測結果 97
A-1-3 測試用CMUT元件光學量測頻率響應結果 99
A-2 測試用CMUT水中超聲波接收量測 100
A-2-1 水中超聲波接收量測架設 100
A-2-2 測試用CMUT超聲波接收性能 103
參考文獻 108

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