CN214315604U - MEMS microphone - Google Patents

Abstract

The utility model provides a MEMS microphone. The MEMS microphone comprises a base with a back cavity, a vibrating membrane spaced from the base, an anchoring portion fixed on the base and surrounding the periphery of the vibrating membrane, and connecting the elastic support between the vibrating film and the anchoring part; the anchoring part is arranged around the outer periphery of the vibrating film and is spaced apart from the vibrating film to form a gap surrounding the vibrating film; The membrane is suspended on one side of the back cavity and falls into the back cavity along the orthographic projection of the axial direction of the substrate, and a baffle is protruded from the area of the diaphragm corresponding to the back cavity. The utility model can improve the problem of the gap expansion of the traditional MEMS microphone diaphragm in the residual stress or vibration process, so as to reduce the loss of its low frequency sensitivity, thereby improving the service life of the MEMS microphone.

Description

MEMS microphone

[ technical field ] A method for producing a semiconductor device

The utility model relates to an acoustoelectric technology field especially relates to a MEMS microphone.

[ background of the invention ]

The MEMS microphone is more and more widely used, and the reliability requirement of the microphone is higher and higher. Taking a capacitive MEMS microphone as an example, the chip includes a substrate having a back cavity, and a diaphragm and a back-plate structure located on the upper portion of the substrate, where the diaphragm and the back-plate structure form a capacitive system. External sound pressure causes the diaphragm to move through the through-hole of the backplate structure, which will change the distance between the diaphragm and the backplate structure, thereby changing the capacitance and ultimately converting into an electrical signal.

Prior art piezoelectric MEMS microphones can be classified into Cantilever beam (Cantilever) microphones and Diaphragm (Diaphragm) microphones. Referring to fig. 1 to 2, in the diaphragm microphone, the diaphragm microphone includes a substrate 20 'having a back cavity 21', a diaphragm 30 'spaced apart from the substrate 20', an anchor portion 40 'fixed to the substrate 20' and surrounding the outer periphery of the diaphragm 30 ', and an elastic support member 50' connecting between the diaphragm 30 'and the anchor portion 40', the anchor portion 40 'surrounding the outer periphery of the diaphragm 30' and spaced apart from the diaphragm 30 'to form a gap surrounding the diaphragm 30'. Under the effect of sound pressure, in the vibration process of the vibrating diaphragm, the width of the gap is increased, so that gas flows through the middle of the gap, and the low-frequency sensitivity of the vibrating diaphragm is reduced due to the fact that the gas acting on the vibrating diaphragm is reduced. In addition, when the diaphragm has residual stress in the existing structure, a height difference is formed between the diaphragm and the plane after the stress is released, and the width of the gap is increased, so that the low-frequency sensitivity is low.

[ Utility model ] content

An object of the utility model is to provide a prevent to lead to the MEMS microphone of vibrating diaphragm sensitivity reduction because of the clearance grow.

In order to achieve the above object, the present invention provides a MEMS microphone, which includes a substrate having a back cavity, a diaphragm spaced apart from the substrate, an anchor portion fixed to the substrate and surrounding the periphery of the diaphragm, and an elastic support member connecting the diaphragm and the anchor portion; the anchoring part is around locating the vibrating diaphragm periphery and with the vibrating diaphragm interval forms and encircles the clearance of vibrating diaphragm, the vibrating diaphragm suspension in back of the body chamber one side and follow the axial orthographic projection of basement falls into in the back of the body chamber, the protruding baffle that is equipped with in the region department that the vibrating diaphragm corresponds the back of the body chamber.

Preferably, a plurality of the elastic supporting members are symmetrically arranged on the periphery of the diaphragm.

Preferably, the baffle extends along the periphery of the diaphragm and is located between two adjacent elastic supporting members.

Preferably, each baffle is arranged symmetrically and at intervals along the periphery of the diaphragm.

Preferably, a single baffle is formed with a recess along the axial direction.

Preferably, a dimension of the baffle in a width direction of the gap is smaller than a length dimension of the baffle in the axial direction.

Preferably, the diaphragm includes a first electrode plate, a piezoelectric diaphragm and a second electrode plate stacked in sequence along a vibration direction, and the first electrode plate is disposed on one side of the diaphragm close to the back cavity.

Preferably, the baffle is arranged on one side of the first electrode plate, which is far away from the piezoelectric membrane; and/or the baffle is arranged on one side, far away from the piezoelectric membrane, of the second electrode plate.

The beneficial effects of the utility model reside in that: the MEMS microphone comprises a substrate with a back cavity, a diaphragm arranged at a distance from the substrate, an anchoring part fixed on the substrate and surrounding the periphery of the diaphragm, and an elastic supporting part connected between the diaphragm and the anchoring part; the anchoring part is around locating the vibrating diaphragm periphery and with the vibrating diaphragm interval forms and encircles the clearance of vibrating diaphragm, the vibrating diaphragm suspension in back of the body chamber one side and follow the axial orthographic projection of basement falls into in the back of the body chamber, the protruding baffle that is equipped with in the region department that the vibrating diaphragm corresponds the back of the body chamber. The utility model discloses can improve traditional MEMS microphone diaphragm clearance at residual stress or the problem that the vibration in-process gap enlarges, reduce its low frequency sensitivity's loss to MEMS microphone's life has been improved.

[ description of the drawings ]

Fig. 1 is a schematic structural diagram of a diaphragm microphone provided in the prior art;

fig. 2 is a schematic cross-sectional view of the diaphragm microphone of fig. 1;

fig. 3 is a schematic structural diagram of a diaphragm microphone according to the present invention;

fig. 4 is a schematic structural diagram of another diaphragm microphone provided by the present invention;

fig. 5 is a schematic structural view of the diaphragm microphone shown in fig. 3 showing a warped structure;

fig. 6 is a schematic view of a warped structure of the diaphragm microphone shown in fig. 4.

[ detailed description ] embodiments

The present invention will be further described with reference to the accompanying drawings and embodiments.

It should be noted that all the directional indicators (such as upper, lower, left, right, front, back, inner, outer, top, bottom … …) in the embodiments of the present invention are only used to explain the relative position between the components in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indicator is changed accordingly.

Referring to fig. 3 to 6, the present invention provides a MEMS microphone, which includes a substrate 20 having a back cavity 21, a diaphragm 30 spaced apart from the substrate 20, an anchor portion 40 fixed to the substrate 20 and surrounding the periphery of the diaphragm 30, and an elastic support member 50 connecting the diaphragm 30 and the anchor portion 40.

Specifically, the anchor portion 40 is arranged around the periphery of the diaphragm 30 and forms a gap surrounding the diaphragm 30 at an interval with the diaphragm 30, the diaphragm 30 is suspended on one side of the back cavity 21 and falls into the back cavity 21 along the axial orthographic projection of the substrate 20, a baffle 60 is convexly arranged at the area of the diaphragm 30 corresponding to the back cavity 21, and the baffle 60 is used for solving the problem of gap expansion caused by residual stress or vibration.

In particular, the substrate 20 is made of a semiconductor material, such as silicon. The back cavity 21 is disposed through the substrate 20, and the back cavity 21 may be formed by a bulk silicon micro-machining process or etching.

Specifically, the diaphragm 30 may be made of a polysilicon-doped or single crystal silicon-doped conductive material.

Specifically, the elastic supporting members 50 are provided in plurality, and the elastic supporting members 50 are symmetrically disposed on the periphery of the diaphragm 30. In one embodiment, the diaphragm 30 is substantially square, the number of the elastic supporting members 50 is four, one end of each of the four elastic supporting members 50 is connected to one corner of the diaphragm 30, and the other end of each of the four elastic supporting members 50 is correspondingly connected to the anchor portion 40.

In one embodiment, please refer to fig. 3 and 5 with more emphasis, the baffle 60 extends along the periphery of the diaphragm 30 and is located between two adjacent elastic supporting members 50. Further, each baffle 60 is symmetrically and alternately arranged along the periphery of the diaphragm 30, and further, a groove 601 is formed in each baffle 60 along the axial direction, and the groove 601 keeps the rigidity of the whole diaphragm 30 unchanged, so that the normal warping height of the diaphragm 30 in the working state is not affected. In addition, the baffle 60 forms a city wall structure along the axial direction, and the city wall structure plays a role in reducing the gap during the residual stress warping or the diaphragm vibration of the gap surrounding the diaphragm 30.

In one embodiment, please refer to fig. 4 and 6 with more emphasis, the baffle 60 extends along the periphery of the diaphragm 30 and is located between two adjacent elastic supporting members 50, and the baffle 60 is a non-spaced baffle to form a complete wall structure. The baffles 60 can adjust the structural state of the diaphragm 30, change the stiffness and equivalent mass of the whole vibration system, adjust the resonant frequency of the vibration system, and optimize the warping height of the diaphragm 30 under the action of residual stress.

The baffles 60 may be present individually or together, as appropriate.

In one embodiment, according to the above situation, the baffle 60 may further include a baffle 60 formed at a middle position of the diaphragm 30 to further adjust the structural state of the diaphragm 30.

According to the above various embodiments, further, the dimension of the baffle 60 in the width direction of the gap is smaller than the length dimension of the baffle 60 in the axial direction.

In one embodiment, the diaphragm 30 includes a first electrode pad 31, a piezoelectric diaphragm 32, and a second electrode pad 33 stacked in sequence along a vibration direction, in terms of material composition of the diaphragm 30, where the first electrode pad 31 is disposed on a side of the diaphragm 30 close to the back cavity 21.

Further, the baffle 60 is arranged on one side of the first electrode sheet 31 far away from the piezoelectric diaphragm 32; and/or the baffle is arranged on one side of the second electrode plate 33 far away from the piezoelectric diaphragm 32. Specifically, the baffle 60 may be adjusted according to actual requirements, and the baffle 60 may be separately disposed above the diaphragm 30, may also be separately disposed below the diaphragm 30, or may be distributed at upper and lower positions of the diaphragm 30.

In one embodiment, the baffle 60 has a cross section of one or more of a rectangle, a circle, a sector or a polygon, and when the sound pressure acts on the diaphragm 30, the airflow will flow out from the gap along the curvature of the warp, and the baffle 60 is placed to block the airflow, thereby increasing the sensitivity of the device.

In one embodiment, the side of the baffle 60 is disposed at an angle to the diaphragm 30, and the side of the baffle 60 may be perpendicular to the diaphragm 30, may be inclined, or may have a certain curvature. Preferably, the side of the baffle 60 is perpendicular to the diaphragm 30.

The utility model provides a MEMS microphone, the MEMS microphone includes the basement that has the back cavity, with the vibrating diaphragm of basement interval setting, be fixed in the basement and encircle the anchor portion of vibrating diaphragm periphery and connect the elastic support piece between vibrating diaphragm and the anchor portion; the anchoring part is around locating the vibrating diaphragm periphery and with the vibrating diaphragm interval forms and encircles the clearance of vibrating diaphragm, the vibrating diaphragm suspension in back of the body chamber one side and follow the axial orthographic projection of basement falls into in the back of the body chamber, the protruding baffle that is equipped with in the region department that the vibrating diaphragm corresponds the back of the body chamber. The utility model discloses can improve traditional MEMS microphone diaphragm clearance at residual stress or the problem that the vibration in-process gap enlarges, reduce its low frequency sensitivity's loss to MEMS microphone's life has been improved.

The above embodiments of the present invention are only described, and it should be noted that, for those skilled in the art, modifications can be made without departing from the inventive concept, but these all fall into the protection scope of the present invention.

Claims (8)

1. An MEMS microphone comprises a substrate with a back cavity, a diaphragm arranged at an interval with the substrate, an anchoring part fixed on the substrate and surrounding the periphery of the diaphragm, and an elastic supporting part connected between the diaphragm and the anchoring part; the anchoring part is around locating the vibrating diaphragm periphery and with the vibrating diaphragm interval forms and encircles the clearance of vibrating diaphragm, the vibrating diaphragm suspension in back of the body chamber one side and follow the axial orthographic projection of basement falls into in the back of the body chamber, its characterized in that, the protruding baffle that is equipped with in the region department that the vibrating diaphragm corresponds the back of the body chamber.

2. The MEMS microphone of claim 1, wherein: the elastic supporting pieces are symmetrically arranged on the periphery of the diaphragm.

3. The MEMS microphone of claim 2, wherein: the baffle extends along the periphery of the diaphragm and is positioned between two adjacent elastic supporting parts.

4. The MEMS microphone of claim 3, wherein: the baffles are arranged symmetrically and at intervals along the periphery of the diaphragm.

5. The MEMS microphone of claim 3, wherein: the single baffle is provided with a groove along the axial direction.

6. The MEMS microphone of claim 1, wherein: the dimension of the baffle in the width direction of the gap is smaller than the length dimension of the baffle in the axial direction.

7. The MEMS microphone of claim 1, wherein: the vibrating diaphragm comprises a first electrode plate, a piezoelectric diaphragm and a second electrode plate which are sequentially stacked along the vibration direction, wherein the first electrode plate is arranged on one side, close to the back cavity, of the vibrating diaphragm.

8. The MEMS microphone of claim 7, wherein: the baffle is arranged on one side, far away from the piezoelectric diaphragm, of the first electrode plate; and/or the baffle is arranged on one side, far away from the piezoelectric membrane, of the second electrode plate.

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