Development of a micromachined piezoelectric microphone for aeroacoustics applications – Journal of the Acoustical Society of America Dec 2007

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.

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