UNSPECIFIED (2001) Novel, wide bandwidth, micromachined ultrasonic transducers. IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL, 48 (6). pp. 1495-1507. ISSN 0885-3010

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Abstract

Surface micromachined, capacitive ultra-sonic transducers have been fabricated using a low thermal budget, CMOS-compatible process. This process allows inherent control of parameters such as membrane size and thickness, cavity size and the intrinsic stress in the membrane to be achieved. Devices fabricated using this process exhibit interesting properties for transduction in air at frequencies in excess of 1 MHz when driven from a standard ultrasonic voltage source. Experiments have been performed with devices containing silicon nitride membranes of variable thicknesses over a 2 mum thick air cavity and with device dimensions of up to 5 mm square. This is much larger than has been reported for a device with a single membrane. Calibration measurements using 1/8 inch microphones in air, and miniature PVDF hyrdophones in water, have been performed. The dependence on d.c. bias voltage is examined, involving static membrane deflection measurements and received peak voltages. Pulse-echo and pitch-catch mode operation have been achieved. Interferometric measurements of membrane displacement have been performed in air to illustrate the membrane deflection characteristics. Operation in liquids is also discussed.

Item Type:	Journal Article
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) T Technology > TK Electrical engineering. Electronics Nuclear engineering
Journal or Publication Title:	IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL
Publisher:	IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC
ISSN:	0885-3010
Date:	November 2001
Volume:	48
Number:	6
Number of Pages:	13
Page Range:	pp. 1495-1507
Publication Status:	Published
URI:	http://wrap.warwick.ac.uk/id/eprint/11480

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