Abstract: A improved micro-electro-mechanical systems(MEMS) piezoelectric microphone with circular diaphragm is developed to improve the sensitivity and the rate of finished product of microphone. Circular supporting wall of diaphragm is fabricated using boron-doped method to avoid stress concentration at four corners of diaphragm on rectangular supporting wall, and the deep boron-doped technique is adopted to increase the thickness of supporting wall and avert “softer” support for diaphragm; The vibrating diaphragm is composed of Si3N4/SiO2/Si3N4 composite films which reduce internal stress; The microphone is divided into some parts which are acoustical parallel connection and electrical series connection using segmenting electrodes in series method to improve the sensitivity. The microphone is fabricated by micromachined technology after structure optimization and tested by comparison method in anechoic chamber. The vibrating diaphragm is flat without wrinkling and the rate of finished product is higher. The sensitivity of microphone has great increased and achieves about 0.3 mV/Pa .

Key words: Circular diaphragm, Micro-electro-mechanical systems(MEMS), Piezoelectric microphone, Segmenting electrodes