A Piezoelectric MEMS Microphone Based on Lead Zirconate Titanate (PZT) Thin Films

Report No. ARL-TR-3387
Authors: Ronald G. Polcawich
Date/Pages: November 2004; 28 pages
Abstract: Piezoelectric microelectromechanical (MEMS) scale acoustic sensors have potential applications in a wide variety of applications including hearing aids, surveillance, and heart monitoring. For each of these systems and many others, the acoustic sensors must be miniaturized and have low power requirements. A piezoelectric-based microphone can provide a solution to these requirements, since it offers the ability to passively sense without the power requirements of condenser or piezoresistive microphone counterparts. This research effort reports on the design and fabrication of a piezoelectric PbZr0.52Ti0.48O3 (PZT) based acoustic sensor. A circular clamped membrane consisting of a dielectric for structural support and a piezoelectric actuator has been fabricated on a silicon wafer via silicon deep reactive ion etching (DRIE). Sensors ranging from 500 to 2000 microns in diameter have been fabricated and characterized with the use of scanning laser Doppler vibrometry and calibrated acoustic tone sources. The PZT sensors exhibited a sensitivity of 97.9 to 920 nV/Pa, depending on geometry.
Distribution: Approved for public release
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Last Update / Reviewed: November 1, 2004