CUED Publications database

Microfabrication of electrode patterns for high-frequency ultrasound transducer arrays.

Bernassau, AL and García-Gancedo, L and Hutson, D and Démoré, CE and McAneny, JJ and Button, TW and Cochran, S (2012) Microfabrication of electrode patterns for high-frequency ultrasound transducer arrays. IEEE Trans Ultrason Ferroelectr Freq Control, 59. pp. 1820-1829.

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Abstract

High-frequency ultrasound is needed for medical imaging with high spatial resolution. A key issue in the development of ultrasound imaging arrays to operate at high frequencies (≥30 MHz) is the need for photolithographic patterning of array electrodes. To achieve this directly on 1-3 piezocomposite, the material requires not only planar, parallel, and smooth surfaces, but also an epoxy composite filler that is resistant to chemicals, heat, and vacuum. This paper reports, first, on the surface finishing of 1-3 piezocomposite materials by lapping and polishing. Excellent surface flatness has been obtained, with an average surface roughness of materials as low as 3 nm and step heights between ceramic/polymer of ∼80 nm. Subsequently, high-frequency array elements were patterned directly on top of these surfaces using a photolithography process. A 30-MHz linear array electrode pattern with 50-μm element pitch has been patterned on the lapped and polished surface of a high-frequency 1-3 piezocomposite. Excellent electrode edge definition and electrical contact to the composite were obtained. The composite has been lapped to a final thickness of ∼55 μm. Good adhesion of electrodes on the piezocomposite has been achieved and electrical impedance measurements have demonstrated their basic functionality. The array was then packaged, and acoustic pulse-echo measurements were performed. These results demonstrate that direct patterning of electrodes by photolithography on 1-3 piezocomposite is feasible for fabrication of high-frequency ultrasound arrays. Furthermore, this method is more conducive to mass production than other reported array fabrication techniques.

Item Type: Article
Uncontrolled Keywords: Aluminum Oxide Electric Impedance Electrodes Microtechnology Transducers Ultrasonography
Subjects: UNSPECIFIED
Divisions: Div B > Solid State Electronics and Nanoscale Science
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:29
Last Modified: 08 Dec 2014 02:34
DOI: 10.1109/TUFFC.2012.2387