Design and Simulation of a Novel High Sensitive MEMS Microphone Based On a Spring-Supported Circular Diaphragm

In this paper, we presented a novel single-chip MEMS capacitive microphone with a spring-supported circular diaphragm. Surface micromachining and backside etching techniques were used to create a flexible diaphragm and a rigid single-crystal backplate for the capacitive microphone. The structure has a diaphragm with a thickness of 2 μm, a diaphragm radius of 400 μm, and an air gap of 2 μm. The slots are made on the diaphragm to reduce the air damping and improve the sensitivity by reducing the mechanical stiffness of the diaphragm. We designed and optimized the structure parameters using electrostatic-mechanical coupling finite element analysis (FEA). The sensitivity and frequency response of the microphone was investigated using a lumped-element model. The proposed microphone’s sensitivity is -29.5 dBv/Pa under 3 V dc bias. The proper design of the perforated backplate results in a bandwidth of nearly 27 kHz. Considering the acoustic-thermal noise, SNR is predicted to be 61.5 dB.