Wafer-bonded 2-D CMUT arrays incorporating through-wafer trench-isolated interconnects with a supporting frame
This paper reports on wafer-bonded, fully populated 2-D capacitive micromachined ultrasonic transducer (CMUT) arrays. To date, no successful through-wafer via fabrication technique has been demonstrated that is compatible with the wafer-bonding method of making CMUT arrays. As an alternative to thro...
| Publié dans: | IEEE transactions on ultrasonics, ferroelectrics, and frequency control. - 1986. - 56(2009), 1 vom: 01. Jan., Seite 182-92 |
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| Auteur principal: | |
| Autres auteurs: | , , , , |
| Format: | Article en ligne |
| Langue: | English |
| Publié: |
2009
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| Accès à la collection: | IEEE transactions on ultrasonics, ferroelectrics, and frequency control |
| Sujets: | Journal Article Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. Soybean Oil 8001-22-7 Silicon Z4152N8IUI |
| Résumé: | This paper reports on wafer-bonded, fully populated 2-D capacitive micromachined ultrasonic transducer (CMUT) arrays. To date, no successful through-wafer via fabrication technique has been demonstrated that is compatible with the wafer-bonding method of making CMUT arrays. As an alternative to through-wafer vias, trench isolation with a supporting frame is incorporated into the 2-D arrays to provide through-wafer electrical connections. The CMUT arrays are built on a silicon-on-insulator (SOI) wafer, and all electrical connections to the array elements are brought to the back side of the wafer through the highly conductive silicon substrate. Neighboring array elements are separated by trenches on both the device layer and the bulk silicon. A mesh frame structure, providing mechanical support, is embedded between silicon pillars, which electrically connect to individual elements. We successfully fabricated a 16 x 16-element 2-D CMUT array using wafer bonding with a yield of 100%. Across the array, the pulse-echo amplitude distribution is uniform (rho = 6.6% of the mean amplitude). In one design, we measured a center frequency of 7.6 MHz, a peak-to-peak output pressure of 2.9 MPa at the transducer surface, and a 3-dB fractional bandwidth of 95%. Volumetric ultrasound imaging was demonstrated by chip-to-chip bonding one of the fabricated 2-D arrays to a custom-designed integrated circuit (IC). This study shows that through-wafer trench-isolation with a supporting frame is a viable solution for providing electrical interconnects to CMUT elements and that 2-D arrays fabricated using waferbonding deliver good performance |
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| Description: | Date Completed 13.08.2009 Date Revised 21.11.2013 published: Print Citation Status MEDLINE |
| ISSN: | 1525-8955 |
| DOI: | 10.1109/TUFFC.2009.1018 |