Implementation of the CMOS MEMS Condenser Microphone with Corrugated Metal Diaphragm and Silicon Back-Plate

This study reports a CMOS-MEMS condenser microphone implemented using the standard thin film stacking of 0.35 mu m UMC CMOS 3.3/5.0 V logic process, and followed by post-CMOS micromachining steps without introducing any special materials. The corrugated diaphragm for the microphone is designed and implemented using the metal layer to reduce the influence of thin film residual stresses. Moreover, a silicon substrate is employed to increase the stiffness of the back-plate. Measurements show the sensitivity of microphone is -42 +/- 3 dBV/Pa at 1 kHz (the reference sound-level is 94 dB) under 6 V pumping voltage, the frequency response is 100 Hz-10 kHz, and the S/N ratio >55 dB. It also has low power consumption of less than 200 mu A, and low distortion of less than 1% (referred to 100 dB).