The Effects of Residual Stresses in the Composite Diaphragm on the Performance of Piezoelectric Microspeakers

作者：Ur Soon Chul; Kim Eun Sok; Yi SeungHwan^*

来源：Electronic Materials Letters, 2013, 9(1): 119-123.

DOI：10.1007/s13391-012-2141-8

• piezoelectric microspeaker
• AlN film
• residual stress
• sound pressure level
• output pressure

Piezoelectric microspeakers are fabricated with AlN film on circular and square Mo/Ti electrodes, and the acoustic pressures are measured with and without packaging structure as a function of frequency. As residual stresses of the composite diaphragm are decreased from +20 MPa to -20 MPa, the output pressure of the fabricated chip (square electrodes) is increased from 1.16 mPa to 96.2 mPa. The packaged microspeaker shows enhanced uniform sound pressure level (SPL) from 1 kHz to 15 kHz with more than 100 dB SPL at 2.50 kHz, with square electrodes in particular. For the circular electrodes, the resonant frequency is revealed to be 3.06 kHz, and the SPL at resonant frequency is measured at 107 dB, which is somewhat higher than for the square electrode. However, the output pressures of the microspeaker show lower values than that of the square electrodes at 1 kHz sinusoidal frequency.

• 出版日期2013-1