Development of a micromachined piezoelectric microphone for aeroacoustics applications

• DOI: 10.1121/1.2785040
• Publication Date: 2008-02-01T00:02:57Z
• Authors: Stephen Horowitz; Toshikazu Nishida; Louis Cattafesta; Mark Sheplak
• Keywords: Titanium; Silicon; Miniaturization; Time Factors; Aircraft; Finite Element Analysis; Reproducibility of Results; Acoustics; Equipment Design; 02 engineering and technology; Electric Capacitance; Vibration; Atmospheric Pressure; Lead; Models, Chemical; Electric Impedance; Zirconium; Noise; 0210 nano-technology

This paper describes the design, fabrication, and characterization of a bulk-micromachined piezoelectric microphone for aeroacoustic applications. Microphone design was accomplished through a combination of piezoelectric composite plate theory and lumped element modeling. The device consists of a 1.80-mm-diam, 3-μm-thick, silicon diaphragm with a 267-nm-thick ring of piezoelectric material placed near the boundary of the diaphragm to maximize sensitivity. The microphone was fabricated by combining a sol-gel lead zirconate-titanate deposition process on a silicon-on-insulator wafer with deep-reactive ion etching for the diaphragm release. Experimental characterization indicates a sensitivity of 1.66μV∕Pa, dynamic range greater than six orders of magnitude (35.7–169dB, re 20μPa), a capacitance of 10.8nF, and a resonant frequency of 59.0kHz.