MEMS microphones, short for microelectromechanical systems microphones, are one of the smallest types of microphones. They have an extremely high-performance level and provide good sensitivity, low power consumption, as well as a high SNR. This type of hardware remains steady when performing and has great features regarding temperature. Importantly, the performance after reflow soldering is quite imperceptible.
MEMS Microphones: Its Fabrication
The fabrication of MEMS microphones is peculiar. They have acoustic sensors created on semiconductor production lines. In addition, they use silicon wafers and work on highly automated processes. Moreover, a variety of materials layers on top of a silicone wafer. Afterwards, a moveable membrane emerges when the excess material is disposed.
Furthermore, MEMS microphones have a fixed backplate located on top of a hole in the bottom wafer. The sensor backplate is a rigid structure that allows airflow, whereas the membrane is a thin structure that can bend when the sound waves cause a change in air pressure. When this happens, the air also flows through the holes on the backplate. However, the backplate remains static. Every time the membrane moves, a change appears in the amount of capacitance, which then generates an electrical signal.
Are MEMS Microphones Perfect?
The short answer for this question is no. MEMS microphones have similar problems than conventional mics. The diffraction effect is one of the principal issues. Regardless, this type of microphones tends to achieve a smoother frequency response because of its simpler mechanical structure. Not only that, but their design includes system resonances that are above the desired frequency. Also, the user can turn to damping to tame the resonance of the overall microphone diaphragm.
Lastly, although large-diaphragm mics are commonly associated with low-noise floor and better overall performance, this might not always be true. Microelectromechanical microphones might not have the best performance in contrast to large-diaphragm microphones, but they are great in terms of the noise floor, sensitivity, and sound vibration.
