mems condenser microphone

Abstract

The invention discloses a MEMS capacitive microphone, comprising a first substrate and a vibrating membrane supported above the first substrate through a spacer, the first substrate, the spacer and the vibrating membrane form a vacuum cavity; wherein the vibrating The static deflection distance of the membrane under atmospheric pressure is less than the distance between the diaphragm and the first substrate; the lower electrode that forms a capacitor structure with the diaphragm is arranged on the substrate at one side of the vacuum chamber, and the diaphragm and the lower electrode The electric field between them is 100‑300V / μm. The microphone of the present invention can form a high electric field in the vacuum chamber without causing breakdown, which greatly improves the sensitivity of the MEMS microphone of the present invention; the vacuum chamber can reduce the influence of sound resistance on the vibration of the diaphragm and improve the signal-to-noise of the microphone In addition, since the MEMS microphone of this structure does not require a larger volume of the back cavity, the overall size of the MEMS microphone can be greatly reduced, and the reliability of the microphone is enhanced.

Description

technical field [0001] The present invention relates to the field of acoustic-electric conversion, more specifically, to a mechanism of a MEMS capacitive microphone, especially a structure of a capacitive microphone with high SNR. Background technique [0002] The current MEMS microphone, whether it is a capacitive sensing structure or a piezoelectric sensing structure, needs to design a huge back cavity with ambient pressure to ensure the rigidity of the flowing air and the far diaphragm. The volume of the dorsal cavity is usually much greater than 1mm 3 , such as usually designed for 1-15mm 3 . Moreover, when the microphone chip is packaged, its cavity needs to be opened. This limits the design of the minimum package size of the MEMS microphone (>3mm 3 ). [0003] This is because if the volume of the rear cavity is too small, it is not conducive to the circulation of air, and the rigidity of this air will greatly reduce the mechanical sensitivity of the diaphragm. ...

AI Technical Summary

Problems solved by technology

This limits the design of the minimum package size of the MEMS microphone (>3mm 3 )

[0003] This is because if the volume of the rear cavity is too small, it is not conducive to the circulation of air, and the rigidity of this air will greatly reduce the mechanical sensitivity of the diaphragm

In addition, for pressure equalization, dense through-holes are usually designed on the back plate, and the air flow resistance in the gap or perforation caused by air viscosity becomes the dominant factor of MEMS microphone noise, thus limiting the high signal-to-noise ratio performance of the microphone

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