mems microphone

Abstract

The invention discloses a MEMS microphone, comprising a first substrate and a diaphragm supported above the first substrate by a spacer, the first substrate, the spacer, and the diaphragm enclose a vacuum cavity; wherein the diaphragm is in The static deflection distance under atmospheric pressure is less than the distance between the diaphragm and the first substrate; it also includes a floating gate field effect transistor for outputting a changing electrical signal, and the floating gate field effect transistor includes a source electrode arranged on the substrate, The drain also includes a floating gate arranged on the diaphragm. In the MEMS microphone of the present invention, a vacuum cavity is formed between the vibrating membrane and the first substrate, thereby reducing the influence of sound resistance on the vibration of the vibrating membrane and improving the signal-to-noise ratio of the microphone. Since the MEMS microphone with this structure does not require a large-volume 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 microphone, especially a microphone structure 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 that the rigidity of the flowing air is much higher than that of the 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. I...

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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