請用此 Handle URI 來引用此文件:
http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/56321
標題: | CMOS-based 電容式微機電超音波換能器操作於崩潰模態之開發 Development of CMOS-based Capacitive Micromachined Ultrasonic Transducers Operated in Collapse-mode |
作者: | Wei-Cheng Chung 鍾威正 |
指導教授: | 田維誠(Wei-Cheng Tian) |
關鍵字: | 互補式金屬氧化物半導體,微機電超音波換能器,崩潰模態, CMOS-MEMS,CMUT,Collapse-mode,Ultrasound, |
出版年 : | 2014 |
學位: | 碩士 |
摘要: | 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,簡稱CMUT),並將CMUT操作於大於崩潰電壓的模態(稱為崩潰模態)。然而本團隊製作CMUT的良率需要提昇,因此本研究第一部分著重於尋找濕蝕刻製程上影響良率的關鍵步驟,發現烤乾後的晶片可以確保良率,目前製作CMUT的良率到達100%;且CMUT在崩潰模態時必須在水中偏壓高達90V的直流電壓,防水鍍膜強度不足使57%的薄膜損壞,且水中漏電現象明顯使電路板氧化,然而提高防水鍍膜厚度使元件特性下降,因此本研究第二部分將防水薄膜厚度最佳化,以及電路板的防水設計。
本研究利用共軛焦顯微鏡呈現崩潰模態時的表面輪廓,量測出CMUT的崩潰電壓在50~60V區間;也呈現CMUT操作於崩潰模態的特性。由於直流偏壓大於崩潰電壓,因此CMUT的靈敏度變好,且薄膜觸底將使中心頻率變化。本研究利用商用Pulser 5077PR與商用探頭發射超音波,CMUT在崩潰模態的接收效率為傳統薄態的4倍,且中心頻率由2.7MHz轉換到7.9MHz;而CMUT做自發自收時,傳統模態的電壓峰對峰值達2.625V,比例頻寬132%,然而由於致動元件的交流電壓遠大於直流偏壓,元件會操作於深崩潰模態,在崩潰模態的自發自收電壓峰對峰值可達3.427V,但比例頻寬下降至40~45%。 In this work, experimental results of Capacitive Micromachined Ultrasonic Transducers (CMUTs) operated in collapse-mode is presented. The device is implemented with the TSMC 0.35μm CMOS-MEMS process. Through the surface profile measured by a confocal microscope, the collapsed voltage is measured at approximately 50 ~ 60V. With a bias voltage over the collapse voltage, the receiving sensitivity of CMUTs is increased 4 times larger and the center frequency is shifted from 2.7MHz to 7.9MHz. Driven by a commercial pulser, the received echo signal using our device in traditional mode is 2.625Vpp and the fractional bandwidth is 132%. Affected by the deep-collapse operation, the largest received echo signal reaches 3.427Vpp and the fractional bandwidth reduced to approximately 40 ~ 45%. The CMUT center frequency shifts from 3.12MHz to 9.12MHz. We also present an improved wet etch process to significantly increase the yield to almost 100%. Depositing thicker sealing membrane material ensures the robustness of CMUTs. Our developed CMUTs operated in DC bias of 90V in a water tank for over half an hour was demonstrated. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/56321 |
全文授權: | 有償授權 |
顯示於系所單位: | 電子工程學研究所 |
文件中的檔案:
檔案 | 大小 | 格式 | |
---|---|---|---|
ntu-103-1.pdf 目前未授權公開取用 | 5.17 MB | Adobe PDF |
系統中的文件,除了特別指名其著作權條款之外,均受到著作權保護,並且保留所有的權利。