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1 October 2001 Piezoelectric aluminum nitride thin films for ultrasonic transducers
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Piezoelectric aluminum nitride (AlN) thin films have been developed to realize ultrasonic transducers. AlN up to 1.5m is deposited at low temperature (140 degree(s)C) by reactive DC magnetron sputtering of an Al target in argon and nitrogen on Si, Si/SiO2/Al, and Si/Al substrates, and is wet etched (rates from 0.1 micrometers /min to 0.2 micrometers /min and selectivity of 1:10 with Al, and no etching with Si). SiO2/Al/AlN/Al, Al/AlN/Al and Si/AlN/Al square and circular membranes, from 10 micrometers to 1.5 mm size are fabricated using silicon deep reactive ion etching (DRIE), which gives etch profiles about 90, which allows larger integration density than wet anisotropic etching for ultrasonic transducers arrays. By varying size and thickness of membranes, resonance frequencies from 10 kHz to 20 MHz are expected, acoustic and electrical measurements are in progress. Ultrasonic transducers using this technology will be used to measure flows velocity by Doppler method. Other potential applications for ultrasonic transducers include medical ultrasounds and sonar. Other structures are also in progress such as Thin Film Bulk Acoustic Resonator (TFBAR), and Lamb wave devices using this technology.
© (2001) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Laurie Valbin and Laure Sevely "Piezoelectric aluminum nitride thin films for ultrasonic transducers", Proc. SPIE 4559, MEMS Components and Applications for Industry, Automobiles, Aerospace, and Communication, (1 October 2001);

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