WO2021237808A1

WO2021237808A1 - Piezoelectric mems microphone

Info

Publication number: WO2021237808A1
Application number: PCT/CN2020/095622
Authority: WO
Inventors: 段炼; 张睿
Original assignee: 瑞声声学科技(深圳)有限公司
Priority date: 2020-05-25
Filing date: 2020-06-11
Publication date: 2021-12-02
Also published as: CN212086487U

Abstract

The present utility model provides a piezoelectric MEMS microphone, comprising a substrate, a diaphragm mounted on the substrate, and a protective flat plate spaced apart from the diaphragm. Reinforcing ribs are provided on the protective flat plate. According to the present utility model, by providing the reinforcing ribs on the protective flat plate of the piezoelectric MEMS microphone, at least partial region of the protective flat plate has a non-rectangular cross section in a direction parallel to the vibration of the diaphragm, the structural strength of the protective flat plate is thus improved, and the protective flat plate is not easy to break under the impact of the diaphragm.

Description

Piezoelectric MEMS microphone

Technical field

The utility model relates to the technical field of sound and electricity, in particular to a piezoelectric MEMS microphone.

Background technique

At present, piezoelectric MEMS microphones have many advantages over traditional capacitive MEMS microphones, including dust and water resistance, and higher maximum output sound pressure (AOP). In order to reduce the deformation caused by the residual stress on the surface of the diaphragm, thereby reducing the noise floor and increasing the sensitivity, many of the diaphragms of piezoelectric MEMS microphones are cantilever beam structures with one end fixed and one end free. Figure 1 shows the design structure of a typical cantilever beam diaphragm of a piezoelectric microphone. In practical applications, because the diaphragm 2 itself is relatively fragile, it is easy to produce a larger impact when subjected to a large impact in a reliability test. Deformation will cause the diaphragm 2 to break or break. Therefore, it is necessary to design a structure to protect the diaphragm 2. As shown in Figure 2, a more common practice is to add a protective flat structure 3 on the upper or lower surface of the diaphragm 2 at a distance from the position to protect it when the diaphragm 2 is greatly deformed by impact. The diaphragm 2 is prevented from further deforming, and the diaphragm 2 is prevented from breaking.

In the previous design, the protective plate 3 is mostly formed by a number of trusses 301 (straight beams) (as shown in FIG. 2) or perforated plates (circular or polygonal holes). The cross section of the truss 301 of the protection plate 3 is mostly rectangular (as shown in FIG. 3), and the rectangular cross section is prone to deformation and fracture, and the strength is limited, and deformation is prone to occur.

Therefore, it is necessary to provide a new piezoelectric MEMS microphone to improve the structural strength of the protective plate.

technical problem

The purpose of the utility model is to provide a piezoelectric MEMS microphone with higher structural strength.

Technical solutions

The technical scheme of the utility model is as follows:

A piezoelectric MEMS microphone includes a base, a vibrating membrane installed on the base, and a protective plate arranged at a distance from the vibrating membrane, and a reinforcing rib is arranged on the protective plate.

Wherein, the reinforcing rib is located at least on any side of the protective plate facing or away from the diaphragm.

Wherein, the reinforcing rib has a rectangular cross section, the rectangular cross section is parallel to the vibration direction of the diaphragm, and the reinforcing rib is only distributed in a partial area of the protective plate.

Wherein, the reinforcing rib has a non-rectangular cross section, and the non-rectangular cross section is parallel to the vibration direction of the diaphragm.

Wherein, the material of the reinforcing rib is silicon nitride.

Wherein, the diaphragm includes a fixed end connected to the base and a suspended free end.

Wherein, the protective plate includes a limiting portion for limiting the free end in the vibration direction of the diaphragm, and an edge fixing portion connected with the base, and the reinforcing ribs are distributed on the limiting portion.

Wherein, the limiting portion is a hollow structure, the limiting portion is formed by a plurality of trusses, and the stiffeners are evenly distributed or randomly distributed along the trusses.

Wherein, the limiting portion is a hollow structure, the limiting portion is formed by a perforated plate, and the reinforcing ribs are evenly distributed or randomly distributed along the perforated plate.

Wherein, the reinforcing rib and the protective plate are integrally formed.

Beneficial effect

The beneficial effects of the utility model are:

The utility model is provided with reinforcing ribs on the protective plate of the piezoelectric MEMS microphone, so that at least part of the area of the protective plate has a non-rectangular section in the direction parallel to the vibration of the diaphragm, which improves the structural strength of the protective plate. The diaphragm is not prone to breakage under the impact.

Description of the drawings

Figure 1 is a schematic diagram of a partial structure of a piezoelectric MEMS microphone in the related art;

2 is a schematic diagram of another part of the structure of a piezoelectric MEMS microphone in the related art;

Figure 3 is a cross-sectional view at A-A in Figure 2;

4 is a top view of part of the mechanism of the piezoelectric MEMS microphone provided by the embodiment of the utility model;

5 is an exploded view of a part of the structure of the piezoelectric MEMS microphone provided by the embodiment of the utility model;

Figure 6 is a schematic diagram of the structure of the protective plate and reinforcing ribs provided by an embodiment of the utility model;

Fig. 7 is a partial enlarged view of B in Fig. 6;

Figure 8 is a first cross-sectional schematic view of the protective plate and the reinforcing rib provided by the embodiment of the utility model;

Figure 9 is a second cross-sectional schematic view of the protective plate and the reinforcing rib provided by the embodiment of the present invention;

Figure 10 is a third cross-sectional schematic view of the protective plate and the reinforcing rib provided by the embodiment of the utility model;

11 is a top view of a partial structure of a piezoelectric MEMS microphone provided by another embodiment of the present invention;

12 is an exploded view of a part of the structure of a piezoelectric MEMS microphone provided by another embodiment of the present invention;

Fig. 13 is a partial enlarged view at C in Fig. 12.

Embodiments of the present invention

In the following, the utility model will be further explained in conjunction with the drawings and embodiments.

4-13, a piezoelectric MEMS microphone includes a substrate 10, a diaphragm 20 mounted on the substrate 10, and a protection connected to the substrate 10 and spaced apart from the diaphragm 20 The plate 30 is provided with reinforcing ribs 40 on the protective plate 30.

The beneficial effects of the utility model are:

In the utility model, the reinforcing rib 40 is arranged on the protective plate 30 of the piezoelectric MEMS microphone, so that the structural strength of the protective plate 30 is improved, and it is not easy to break under the impact of the diaphragm 20.

Further, the reinforcing rib 40 is located at least on any side of the protective plate 30 facing or away from the diaphragm.

Optionally, and referring to FIG. 8, the reinforcing rib 40 has a rectangular cross section, the rectangular cross section is parallel to the vibration direction of the diaphragm 20, and the reinforcing ribs are only distributed in a partial area of the protective plate.

Optionally, and referring to FIGS. 9 to 10, the reinforcing rib 40 has a non-rectangular cross-section, and the non-rectangular cross-section is parallel to the vibration direction of the diaphragm 20. Specifically, the cross-sectional shape of the reinforcing rib 40 may be triangular or T-shaped.

In the above-mentioned embodiment, the reinforcing rib 40 on the protective plate 30 may have a single-shaped cross-sectional structure, or a combination of multiple different-shaped cross-sectional structures.

Optionally, the material of the reinforcing rib 40 is silicon nitride. Silicon nitride is generally formed by chemical weather deposition. By adjusting the deposition process parameters, the magnitude and direction of the stress inside the silicon nitride can be controlled. Regarding the structure of the protective plate 30, adjusting the magnitude and direction of the stress existing in the diaphragm 20 can make the protective plate 30 in a "tight" state. With the reinforcement ribs 40, the stability and strength of the protective plate 30 can be further improved.

It should be noted that the protective plate 30 and the reinforcing rib 40 can be made of the same material or different materials, and the two can be integrally formed or formed separately during the processing.

Further, the diaphragm 20 includes a fixed end 21 connected to the base 10 and a suspended free end 22.

Furthermore, the protective plate 30 includes a limiting portion 31 for limiting the free end 22 in the vibration direction of the diaphragm 20, and an edge fixing portion 32 connected to the base 10, and the reinforcing rib 40 Distributed in the limiting portion 31.

Optionally, and referring to FIGS. 4 to 7, the limiting portion 31 is a hollow structure, the limiting portion 31 is formed by a plurality of trusses, and the reinforcing ribs 40 are evenly distributed or randomly distributed along the trusses. Specifically, each truss is provided with one or more reinforcement ribs 40, or part of the truss is provided with one or more reinforcement ribs 40.

Optionally, and referring to FIGS. 11 to 13, the limiting portion 31 is a hollow structure, the limiting portion 31 is formed of a perforated plate, and the reinforcing ribs 40 are evenly distributed or randomly distributed along the perforated plate. Specifically, reinforcing ribs 40 are provided around each hole of the perforated plate, or reinforcement ribs 40 are provided around part of the holes of the perforated plate.

The above are only the embodiments of the present utility model. It should be pointed out here that for those of ordinary skill in the art, improvements can be made without departing from the inventive concept of the present utility model, but these all belong to The scope of protection of the utility model.

Claims

A piezoelectric MEMS microphone is characterized in that it comprises a substrate, a diaphragm installed on the substrate, and a protective plate arranged at a distance from the diaphragm, and a reinforcing rib is arranged on the protective plate.
The piezoelectric MEMS microphone according to claim 1, wherein the stiffener is located at least on either side of the protective plate facing or away from the diaphragm.
The piezoelectric MEMS microphone according to claim 1, wherein the stiffener has a rectangular cross section, the rectangular cross section is parallel to the vibration direction of the diaphragm, and the stiffener is only distributed on the protective plate Part of the area.
The piezoelectric MEMS microphone according to claim 1, wherein the reinforcing rib has a non-rectangular cross section, and the non-rectangular cross section is parallel to the vibration direction of the diaphragm.
The piezoelectric MEMS microphone according to any one of claims 1 to 4, wherein the material of the reinforcing rib is silicon nitride.
The piezoelectric MEMS microphone of claim 5, wherein the diaphragm includes a fixed end connected to the base and a suspended free end.
The piezoelectric MEMS microphone according to claim 6, wherein the protective plate includes a limiting portion for limiting the free end in the vibration direction of the diaphragm, and an edge fixing portion connected with the substrate Part, the reinforcing ribs are distributed on the limiting part.
7. The piezoelectric MEMS microphone according to claim 7, wherein the limiting portion is a hollow structure, the limiting portion is formed by a plurality of trusses, and the stiffeners are evenly distributed or randomly distributed along the trusses.
7. The piezoelectric MEMS microphone according to claim 7, wherein the limiting portion is a hollow structure, the limiting portion is formed of a perforated plate, and the reinforcing ribs are evenly distributed or randomly distributed along the perforated plate.
The piezoelectric MEMS microphone according to claim 1, wherein the reinforcing rib and the protective plate are integrally formed.