A ~1 MHz piezoelectric micromachined ultrasonic transducer (pMUT) array with ultra-high element density and low crosstalk is proposed for the first time. This novel pMUT array is based on a nano-layer spin-coating lead zirconium titanium film technique and can be fabricated with high element density using a relatively simple process. Accordingly, key fabrication processes such as thick piezoelectric film deposition, low-stress Si-SOI bonding and bulk silicon removal have been successfully developed. The novel fine-pitch 6 × 6 pMUT arrays can all work at the desired frequency (~1 MHz) with good uniformity, high performance and potential IC integration compatibility. The minimum interspace is ~20 μm, the smallest that has ever been achieved to the best of our knowledge. These arrays can be potentially used to steer ultrasound beams and implement high quality 3-D medical imaging applications.
References
[1]
Tournemaine, N.; Chetanneau, A.; Digabel-Chabay, C.; Weber, J.; Peltier, P.; Chatal, J.F.; Gillot, P. Difficulties of the X-ray computed tomographic diagnosis of pelvic tumor recurrence: Comparison with other medical imaging techniques (ultrasonography, immunoscintigraphy). Ann. Radiol. (Paris) 1988, 31, 426–432.
[2]
Doppler Sonographic Imaging of the Vascular System. Report of the Ultrasonography Task Force. In JAMA; Council on Scientific Affairs, American Medical Association, 1991; Volume 265, pp. 2382–2387.
[3]
Campani, R. State of the Art in Ultrasonography and Present Day Imaging Modalities of the Breast. Proceedings of the 38th Congress of the Italian Association of Medical Radiology (SIRM), Milan, Italy, 23？27 May 1998; Volume 27 Suppl. 2, pp. S133–S281.
[4]
Ultrasonic Imaging of the Abdomen. Report of the Ultrasonography Task Force. In JAMA; Council on Scientific Affairs, American Medical Association, 1991; Volume 265, pp. 1726–1731.
[5]
Gudmundsen, T.E.; Vinje, B.; Ostensen, H.; Pedersen, H.K. Ultrasonography in medical imaging. Influence on diagnostic routines. Clin. Imaging 1994, 18, 31–35.
Noble, R.A.; Davies, R.R.; Day, M.M.; Koker, L.; King, D.O.; Brunson, K.M.; Jones, A.R.D.; McIntosh, J.S.; Hutchins, D.A.; Robertson, T.J.; et al. A cost-effective and manufacturable route to the fabrication of high-density 2D micromachined ultrasonic transducer arrays and (CMOS) signal conditioning electronics on the same silicon substrate. Ultrason. Symp. 2001, 2, 941–944.
[11]
Guyonvarch, J.; Certon, D.; Ratsimandresy, L.; Patat, F.; Lethiecq, M. Analytical 2D model of transducer arrays for predicting elementary electroacoustic response and directivity pattern. Ultrason. Symp. 2002, 2, 1217–1220.
Pedersen, T.; Zawada, T.; Hansen, K.; Lou-Moeller, R.; Thomsen, E. Fabrication of high-frequency pMUT arrays on silicon substrates. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 2010, 57, 1470–1477.
[14]
Ferrer-Costa, C.; Gelpi, J.L.; Zamakola, L.; Parraga, I.; de la Cruz, X.; Orozco, M. PMUT: A web-based tool for the annotation of pathological mutations on proteins. Bioinformatics 2005, 21, 3176–3178.
[15]
Wang, Y.F.; Ren, T.L.; Yang, Y.; Chen, H.; Zhou, C.J.; Wang, L.G.; Liu, L.T. High-Density Pmut Array for 3-D Ultrasonic Imaging Based on Reverse-Bonding Structure. Proceedings of the 2011 IEEE 24th International Conference on Micro Electro Mechanical Systems (MEMS), Cancun, Mexico, 23–27 January 2011; pp. 1035–1038.
[16]
Zhuang, X.F.; Ergun, A.S.; Oralkan, O.; Wygant, I.O.; Khuri-Yakub, B.T. Interconnection and Packaging for 2D Capacitive Micromachined Ultrasonic Transducer Arrays Based on Through-Wafer Trench Isolation. Proceedings of the MEMS 2006: 19th IEEE International Conference on Micro Electro Mechanical Systems, Technical Digest, Istanbul, Turkey, 22–26 January 2006; pp. 270–273.
Lin, D.S.; Zhuang, X.; Wodnicki, R.; Woychik, C.G.; Oralkan, O.; Kupnik, M.; Khuri-Yakub, B.T. Packaging of Large and Low-Pitch Size 2D Ultrasonic Transducer Arrays. Proceedings of the MEMS 2010: 23rd IEEE International Conference on Micro Electro Mechanical Systems, Technical Digest, Wanchai, Hong Kong, 24–28 January 2010; pp. 508–511.
[19]
Dausch, D.E.; Castellucci, J.B.; Chou, D.R.; von Ramm, O.T. Theory and operation of 2-D array piezoelectric micromachined ultrasound transducers. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 2008, 55, 2484–2492.
[20]
Mo, J.H.; Fowlkes, J.B.; Robinson, A.L.; Carson, P.L. Crosstalk reduction with a micromachined diaphragm structure for integrated ultrasound transducer arrays. IEEE Trans. Ultrason. Ferroelectr. Freq. Control 1992, 39, 48–53.
[21]
Ren, T.L.; Chen, H.; Yang, Y.; Zhu, Y.P.; Fu, D.; Wang, C.; Wu, X.M.; Cai, J.; Liu, L.T.; Li, Z.J. Micromachined Piezoelectric Acoustic Device. Proceedings of the 2009 2nd International Workshop on Electron Devices and Semiconductor Technology, Mumbai, Indian, 1–2 June 2009; pp. 213–218.
[22]
Wang, Y.F.; Yang, Y.; Ren, T.L.; Chen, H.; Liao, W.J.; Kong, X.M.; Wang, L.G.; Zhou, C.J.; Fu, D.; Liu, L.T. Ultrasonic Transducer Array Design For Medical Imaging Based on MEMS Technologies. Proceedings of the 2010 3rd International Conference on Biomedical Engineering and Informatics (BMEI 2010), Yantai, China, 16–18 October 2010; Volume 1–7, pp. 666–669.
[23]
Fu, D.; Ren, T.L.; Chen, H.; Yang, Y.; Kong, X.M.; Ren, Y.; Liao, W.J.; Liu, L.T. A Novel Method for Fabricating 2-D Array Piezoelectric Micromachined Ultrasonic Transducers for Medical Imaging. Proceedings of the 18th IEEE International Symposium on the Applications of Ferroelectrics, Xian, China, 23–27 August 2009.
Li, H.; Li, Y.C.; Zhou, D.; Peng, J.; Luo, H.S.; Dai, J.Y. Application of PMNPT Single Crystal in a 3.2 MHz Phased-Array Ultrasonic Medical Imaging Transducer. Proceedings of the 2007 Sixteenth IEEE International Symposium on the Applications of Ferroelectrics, Nara, Japan, 27–31 May 2007; Volumes 1 and 2, pp. 569–571.
