Study of a highly sensitive miniature condenser microphone based on MEMS technology

Nowadays, great enthusiasm is devoted to miniature microphone based on Microelectromechanical System (MEMS). For micromechined membrane, there is significantinternal (residual) stress, which strongly decreases the mechanical sensitivity of membrane. As predicted by theoretical analysis and numerical simulation, the application of corrugated membrane offers the possibility to eliminate the effect of initial stress and thus to increase the sensitivity of membrane without changing process conditions. A MEMS-based condenser miniature microphone with corrugated diaphragm has been presented and realized, the fabrication process is simple, efficient and fully compatible with standard IC process. Wafer level measurement has been carried out. An open circuit sensitivity of 40 mv/Pa up to 7 kHz could be achieved under a low bias voltage of 10 V with only 1.5×1.5 mm² chip area. The preamplifier and subsequent signal process circuits should be integrated in the same chip to make a complete micro acoustics system.