基于高压应力的氮化铝MEMS压电微扬声器

A piezoelectric micromachined micospeaker with highly c-axis oriented AlN(Aluminium Nitride)thin films was fabricated by a CMOS-compatible fabrication process. The effects of residual stress on device performance were investigated and two AlN thin films were deposited with heavily compress stress as the piezoelectric and supporting layer to enhance the sound pressure output of the microspeaker,the total residual stress of the diaphragm structure were controlled by a simple,robust fabrication process to give more deflection of the diaphragm. The diameter of the microspeaker is only 1.35 mm and thickness is 0.95 μm. The sound pressure level(SPL)has been measured with a variation of sinusoidal input frequency from 0.5 kHz to 20 kHz. The largest SPL of this microspeaker was about 75 dB at 20 Vpeak-to-peak,which was test at the distance of 10 mm from the microspeaker in open field. The results show its potential for the application in earphone,wearable devices and Internet of things(IoT).