臺灣博碩士論文加值系統

本研究利用TSMC 0.35μm 2P4M CMOS-MEMS製程製作電容式微機電超音波換能器(Capacitive Micromachined Ultrasonic Transducers, CMUTs)，並基於先前單元件CMUTs與零偏壓操作的研究成果，開發微型陣列超音波換能器，並將之應用於生醫超音波成像。
本論文將先簡介元件結構的設計、製程過程、良率改善的成果與電荷累積模型的運用。元件結構的部分沿襲過去研究，並在製程流程上調整改進，跟過去製程相比減少一半所需的時間。此外利用電荷累積模型建立CMUTs驗證的步驟，排除因離子汙染或是薄膜特性缺陷造成無法收發訊號的問題，更配合電荷累積模型提升元件的收發性能，在相同量測條件下提升約1.9倍訊號雜訊比，並盡可能將同一晶片不同元件間效能達到一致，也針對CMUTs進行多種性能量測，了解CMUTs訊號穿透深度與訊號衰減的情形，以上測試建立CMUTs陣列超音波換能器完整的性能資訊。
本研究同時著力於陣列超音波換能器的開發，配合國研院晶片中心(Chip Implementation Center, CIC)提供之PCB板製程服務，研究成果包含開發12MHz的CMUTs陣列元件以及與晶片搭配之雙面硬式電路板的設計與封裝，製作出陣列超音波換能器的原型，並成功繪製B-mode影像且進行分析，以期成為傳統商用壓電探頭的替代選項。

In this study, a phased-array of zero-bias CMOS-based Capacitive Micro-machined Ultrasonic Transducers (CMUTs) with high sensitivity is developed. The device is implemented with the TSMC 0.35µm 2P4M CMOS-MEMS process. Based on the previous research at the CMUT cell and zero-bias operation, this thesis presents a successful achievement on the development of 12 MHz phased-array CMUTs and its application in biomedical imaging.
The thesis will first introduce the CMUTs design and the improved post CMOS process of fabrication, which can significantly enhance performance and the yield of CMUTs. The improvement of post CMOS process includes changing previous process steps to speed up fabrication and verifying CMUTs by I-V scan. Besides, the characteristic of CMUTs’ performances based on transmit signal, receive signal, pulse-echo signal, SNR ratio, penetration of depth, and attenuation-time curve were studied and analyzed in this thesis. The performance enhances 90% compared to previous works.
Last but not least, the thesis will present the prototype of CMUTs tube package and its B-mode scanning imagines. These detail analyses provide necessary and vital information for the future application of CMUTs.

第一章 緒論與研究動機 1
1.1電容式超音波換能器介紹 2
1.1.1電容式超音波換能器架構 2
1.1.2 電容式超音波換能器工作原理與操作 2
1.1.3 陣列成像原理 5
1.2 文獻回顧 7
1.2.1 CMUTs元件設計 7
1.2.2 陣列電容式超音波換能器開發 8
1.2.3 電容式超音波換能器電荷累積特性 11
1.2.4 電容式超音波陣列換能器封裝與應用 12
1.3 研究動機 16
第二章 電容式超音波陣列換能器設計與製程改良 17
2.1 CMUTs陣列設計與模擬 17
2.2 後製程改良 20
2.2.1後製程步驟 20
2.2.2良率改善與關鍵步驟 26
2.2.3驗證流程建立 27
2.2.4 CMUTs晶片耐受性 32
2.3 雙面硬式電路板設計與封裝 34
第三章 電容式超音波陣列換能器特性量測與分析 36
3.1 超音波探頭性能測試 36
3.1.1特性量測儀器架設與流程 36
3.1.2 CMUTs傳輸功能測試 39
3.1.3 CMUTs接收功能測試 41
3.1.4 CMUTs自發自收能力測試 42
3.1.5 CMUTs晶片比較 45
3.2 CMUTs訊號穿透能力測試 47
3.3 CMUTs疲勞度測試 50
第四章 電容式超音波陣列換能器應用 51
4.1 電容式超音波陣列換能器B-mode影像繪製 51
4.1.1量測儀器架設 51
4.1.2陣列影像量測結果 53
4.2生醫成像應用 56
4.2.1管狀電容式超音波陣列換能器封裝 56
4.2.2管內量測 59
4.2.3生醫成像量測結果 59
第五章 結論與未來展望 61
5.1結論 61
5.2未來展望 62
5.2.1元件與系統設計的優化 62
5.2.2封裝設計與CMUTs未來應用 63
Reference 65
附錄 72

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