Design and development of silicon condenser microphone with a novel diaphragm-backplate structure

Abstract

In this project, a novel diaphragm-backplate structure for silicon condenser microphone is proposed. A single deep corrugation technique is applied to the microphone diaphragm to reduce its initial stress and to improve its performance. The advantage of this technique is its ability to reduce the initial stress without increasing in the diaphragm stiffness. Hence, a higher microphone sensitivity can be achieved. The proposed diaphragm-backplate structure is applied to a silicon condenser microphone which has been fabricated and tested. The results obtained to date are quite encouraging. Measured open circuit sensitivity as high as 9.6 mV/Pa with a flat frequency response bandwidth of up to 19 kHz has been achieved for the fabricated microphone. The external bias voltage is applied at 5V with a diaphragm's initial stress of 90 MPa. With these encouraging results, it is believed that the proposed silicon condenser microphone is promising for various acoustics applications.