MEMS piezoelectric acoustic transducer

This paper presents the fabrication process and measurement results of microelectromechanical (MEMS) piezoelectric acoustic transducers. To increase the output sound pressure, a dome-shaped multi-layer diaphragm is designed and fabricated by adjusting the residual stress in the individual layers. Transducers work in either audio or ultrasonic frequency range if diaphragm is designed in different size. In the frequency range from 100 Hz to 7 kHz, the output sound pressure of audio transducers with 3 mm x 3 mm diaphragm is higher than 0.1 Pa. The maximum output reaches 1.1 Pa at 3.8 kHz. For ultrasonic transducers with I mm x I mm diaphragm, the maximum output is 1.26 Pa at resonant frequency of 54 kHz. All transducers show acceptable linearity over a wide range of input drive voltage.