Abstract
This work describes the design and implementation of a CMOS-MEMS capacitive microphone. The microphone with a novel micro-structure design has a high sensitivity in a small area. The post-process is simple and can be completed at low temperatures. Without additional thin film deposition, it is easy to be integrated with the CMOS process on a single chip. The sensor is fabricated by using TSMC 0.35-um 2P4M CMOS process. After metal wet etching to release the micro-structure, a dry etching is performed to remove passivation layers to open the I/O pads. This chip contains five different sets of microphones, and the total chip size is 2.46x2.46 mm2. The power supply of each set is 3.3 V; the current consumption is 1.04 mA; the area of micro-structure is 190x190 um2; and the area of each set is 0.95x0.8 mm2 (including I/O pads). The sensitivity is -37.21 dBV/Pa measured at 1 Pa and 1 kHz; the signal-to-noise ratio is 57dB; the equivalent input noise is 3.16 uV/√Hz; the coherence is 0.98; and the sensor bandwidth is 2.32 kHz.