CN212064359U

CN212064359U - Back electrode plate and micro-electro-mechanical system microphone

Info

Publication number: CN212064359U
Application number: CN202020839883.6U
Authority: CN
Inventors: 荣根兰; 孙恺; 胡维
Original assignee: Memsensing Microsystems Suzhou China Co Ltd
Current assignee: Memsensing Microsystems Suzhou China Co Ltd
Priority date: 2020-05-19
Filing date: 2020-05-19
Publication date: 2020-12-01
Anticipated expiration: 2030-05-19

Abstract

The utility model discloses a back polar plate and micro-electromechanical system microphone, this back polar plate includes: at least three different areas of apertures, with the outermost apertures surrounding other types of apertures. The utility model provides a technical scheme flows in from the hole of periphery to the corruption border control accurate to the sacrificial layer material between vibrating diaphragm and the backplate through corrosive liquid, obtains the second sacrificial layer structure that cross sectional shape and preset shape conform, has improved the life-span of micro-electromechanical system microphone.

Description

Back electrode plate and micro-electro-mechanical system microphone

Technical Field

The embodiment of the utility model provides a relate to microphone technical field, especially relate to a back plate and micro-electromechanical system microphone.

Background

With the development of wireless communication, more and more mobile phone users are worldwide. People have higher and higher requirements on call quality. Micro Electro Mechanical System (MEMS) microphones are currently used. The MEMS microphone adopts a capacitive principle, and comprises a substrate, a first sacrificial layer structure, a vibrating diaphragm, a second sacrificial layer structure and a back plate which form a parallel plate capacitor structure. After the vibrating diaphragm senses an external audio sound pressure signal, the distance between the vibrating diaphragm and the back plate is changed, the capacitance capacity and the voltage are changed, and then the capacitance change is converted into the change of a voltage signal through the integrated circuit chip and output.

In the forming process of the MEMS microphone chip, usually, the etching liquid flows into the acoustic hole on the back plate, and the oxide layer between the diaphragm and the back plate etches the sacrificial layer material between the diaphragm and the back plate according to the preset path and time, thereby obtaining the second sacrificial layer structure. However, due to the limitation of the position of the sound hole on the back plate, the actual cross section shape of the second sacrificial layer structure is different from the preset shape, so that when the diaphragm deforms under the action of sound waves, the diaphragm breaks due to stress concentration, the sensitivity of the device fails, and the service life of the MEMS microphone is shortened.

SUMMERY OF THE UTILITY MODEL

In view of this, the embodiment of the present invention provides a back plate structure and a MEMS microphone, which can improve the life of the MEMS microphone.

In a first aspect, an embodiment of the present invention provides a back plate, including:

at least three different areas of apertures, with the outermost apertures surrounding other types of apertures.

In a second aspect, an embodiment of the present invention provides a mems microphone, including:

a micro-electro-mechanical system microphone chip, an application specific integrated circuit chip, a base and a housing;

the micro-electro-mechanical system microphone chip and the special integrated circuit chip are fixed on the base and are electrically connected;

the mems microphone chip includes the backplate of any of the first aspects.

In the technical proposal provided by the utility model, the back plate comprises at least three holes with different areas, wherein the outermost hole surrounds other holes and holes, corrosive liquid flows into the sacrificial layer material between the vibrating diaphragm and the back plate from the three holes with different areas respectively to corrode the sacrificial layer material, wherein, the outermost hole surrounds other types of holes, which can ensure that the corrosive liquid flows into the sacrificial layer material between the diaphragm and the back plate from the outermost hole to accurately control the corrosion boundary, so that the second sacrificial layer structure with the preset cross section shape can be obtained, the phenomenon that the sacrificial layer material is remained at the part of the vibrating diaphragm which is vibrated under the action of sound wave is avoided, when the vibrating diaphragm vibrates under the action of sound waves, the stress of the vibrating diaphragm on the releasing boundary of the second sacrificial layer is uniformly distributed, the mechanical performance of the MEMS microphone chip is improved, failure does not occur, and the service life of the MEMS microphone is prolonged.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:

fig. 1 is a schematic structural diagram of a back plate according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of another back plate according to an embodiment of the present invention;

fig. 3 is a schematic cross-sectional view of the release hole C-C' of fig. 2 according to an embodiment of the present invention;

fig. 4 is a schematic cross-sectional view of another release hole C-C' in fig. 2 according to an embodiment of the present invention;

FIG. 5 is a schematic cross-sectional view of another release hole C-C' of FIG. 2 according to an embodiment of the present invention;

fig. 6 is a schematic cross-sectional view of another release hole C-C' in fig. 2 according to an embodiment of the present invention;

fig. 7 is a schematic cross-sectional view of another release hole C-C' in fig. 2 according to an embodiment of the present invention.

Fig. 8 is a schematic structural diagram of a mems microphone according to an embodiment of the present invention;

fig. 9 is a schematic structural diagram of another mems microphone according to an embodiment of the present invention;

fig. 10 is a schematic structural diagram of a mems microphone chip according to an embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

As described in the above background art, the actual cross-sectional shape of the second sacrificial layer structure between the diaphragm and the back plate is different from the preset shape, resulting in a short lifetime of the MEMS microphone. The reason is that, the sound holes in the prior art are unevenly distributed on the back plate, so that corrosive liquid flows into the sound holes on the back plate to corrode the sacrificial layer material between the vibrating diaphragm and the back plate, the preset corrosion position of the sacrificial layer material is not completely corroded, the cross section shape of the second sacrificial layer structure is inconsistent with the preset shape, the phenomenon that the vibrating diaphragm has the sacrificial layer material in the part which vibrates under the action of sound waves is caused, the vibrating diaphragm is deformed under the action of sound waves, the vibrating diaphragm is broken due to stress concentration, the sensitivity of the device is caused to fail, and the service life of the MEMS microphone is shortened.

To the technical problem, the embodiment of the utility model provides a following technical scheme is proposed:

fig. 1 is a schematic structural diagram of a back plate according to an embodiment of the present invention. Referring to fig. 1, the back plate 1 according to the embodiment of the present invention includes at least three holes with different areas, wherein the outermost hole a surrounds other types of holes b and c.

It should be noted that, in the embodiment of the present invention, it is not limited that the outermost hole a is smaller than the other types of holes b and c. Fig. 1 is merely exemplary showing that the outermost hole a is smaller than the other types of holes b and c.

The utility model provides an among the technical scheme, the back plate includes the hole of at least three kinds of different areas, wherein hole a outside surrounds hole b and hole c of other types, corrosive liquid flows in to corrode the sacrificial layer material between vibrating diaphragm and the back plate from the hole of three kinds of different areas respectively, wherein, hole a outside surrounds hole b and hole c of other types, can guarantee that corrosive liquid flows in to control the corruption border of sacrificial layer material between vibrating diaphragm and the back plate from hole a outside, so that can obtain the second sacrificial layer structure of predetermineeing cross sectional shape, do not have the vibrating diaphragm and remain the phenomenon that has the sacrificial layer material in the part that receives the acoustic wave action to vibrate, make the vibrating diaphragm when receiving the acoustic wave action to vibrate, the vibrating diaphragm is along the stress distribution on second sacrificial layer release border evenly, the mechanical properties of MEMS microphone chip improves, do not take place inefficacy, thereby improving the service life of the MEMS microphone.

Fig. 2 is a schematic structural diagram of another back plate according to an embodiment of the present invention. Alternatively, referring to fig. 2, the outermost hole a includes a plurality of release holes 110, the main function of which is to pass the corrosive solution. Other types of holes include a plurality of sound holes and a plurality of bleed holes, wherein hole b includes a plurality of sound holes. The hole c includes a plurality of relief holes 102.

Specifically, referring to fig. 2, the back plate 1 includes: a plurality of sound holes 10, a plurality of relief holes 102, and a plurality of relief holes 110; wherein the plurality of discharge holes 12 are disposed around the plurality of sound holes 10 and the plurality of discharge holes 102, and the areas of the sound holes 10, the discharge holes 102, and the discharge holes 110 are different from each other.

It will be appreciated that the plurality of sound holes 10 include a first sound hole 100 located at a central position a of the back plate 1, and a plurality of sound hole groups each including a plurality of second sound holes 101, which are divided at a distance from the center a of symmetry of the back plate 1. Illustratively, FIG. 2 shows 4 acoustic port groups. The 4 sound hole groups divided by the distance from the center a of symmetry of the backplate 1 are a sound hole group B1, a sound hole group B2, a sound hole group B3, and a sound hole group B4, respectively.

Referring to fig. 2, the sound hole group includes a plurality of second sound holes 101, in each sound hole group, the geometric centers of the plurality of second sound holes 01 enclose a polygon, and the number of the second sound holes 101 on each side of the polygon may be the same or different. The air release hole 102 is located in the second sound hole 101, so that the distribution of the second sound hole 101 and the air release hole 102 on the back plate 1 is not uniform. If the corrosive liquid only flows into from the sound hole 10 and the air release hole 102 to corrode the sacrificial layer material between the diaphragm and the back plate 1, the preset corrosion position of the sacrificial layer material is not completely etched by the corrosive liquid, so that the section shape of the second sacrificial layer structure is not consistent with the preset shape, and the phenomenon that the sacrificial layer material remains in the part of the diaphragm which vibrates under the action of sound waves exists, so that when the diaphragm deforms under the action of sound waves, the diaphragm is broken due to stress concentration, the sensitivity of a device is caused to fail, and the service life of the MEMS microphone is shortened.

Continuing to refer to fig. 2, the back plate 1 is further provided with a plurality of release holes 110, corrosive liquid flows into the sacrificial layer material between the diaphragm and the back plate 1 from the sound holes 10, the air release holes 102 and the release holes 110 respectively to corrode the sacrificial layer material between the diaphragm and the back plate 1, wherein the release holes 110 are arranged around the plurality of sound holes 10 and the plurality of air release holes 102, and the corrosive liquid flows into the sacrificial layer material between the diaphragm and the back plate 1 from the release holes 110 to control the corrosion boundary accurately, so that a second sacrificial layer structure with a preset cross-sectional shape can be obtained.

Illustratively, the open area of the release holes 110 is smaller than the open area of the sound holes 10 and the open area of the relief holes 102, and the plurality of sound holes 10 and the plurality of relief holes 102 are disposed around, so that the accuracy of controlling the erosion boundary of the sacrificial layer material between the diaphragm and the back plate 1, which is caused by the flow of the corrosive liquid from the release holes 110, can be increased.

It should be noted that the air release hole 102 not only allows corrosive liquid to flow in to complete corrosion of the sacrificial layer material between the back plate 1 and the diaphragm, but also has a more important function of rapidly discharging excess gas in the cavity of the MEMS microphone chip to adjust the air pressure in the cavity of the MEMS microphone chip, thereby enhancing the drop resistance of the MEMS microphone chip. Besides allowing corrosive liquid to flow in to complete the corrosion of the sacrificial layer material between the back plate 1 and the diaphragm, the sound holes 10 also have the main function of allowing the diaphragm to deform when sound waves enter and are transmitted to the diaphragm, so that air in the air gap is compressed, and the sound holes in the back plate allow the air to flow out to reduce damping. The release holes 110 primarily allow the corrosive liquid to flow into and complete the corrosion of the sacrificial layer material between the backplate 1 and the diaphragm.

It should be noted that the position of the outermost hole a on the back plate 1 may also affect the corrosion boundary of the sacrificial layer material between the diaphragm and the back plate 1 when the outermost hole a of the corrosive liquid flows into the back plate 1.

Optionally, each outermost hole a is a predetermined distance from the central position a of the back plate 1, and the predetermined distances from the outermost holes a to the central position a of the back plate 1 are uniformly distributed within a predetermined threshold.

The outermost hole a is a release hole 110, the hole b includes a plurality of sound holes, and the hole c includes a plurality of release holes 102.

Each release hole 110 is a preset distance from the central position a of the back plate 1, and the preset distances from the plurality of release holes 110 to the central position a of the back plate 1 are uniformly distributed within a preset threshold.

Specifically, the corrosive liquid flows into the sacrificial layer material between the diaphragm and the back plate 1 from the sound holes 10, the air release holes 102 and the release holes 110 respectively to corrode the sacrificial layer material between the diaphragm and the back plate 1, and the preset distances from the sound holes 10 and the air release holes 102 to the central position a of the back plate 1 are uniformly distributed within the preset threshold, so that the release holes 110 and the sound holes 10 and the air release holes 102 keep the same distribution rule, and in addition, the release holes 110 are arranged around the sound holes 10 and the air release holes 102, the corrosive liquid can be ensured to flow into the corrosion boundary of the sacrificial layer material between the diaphragm and the back plate 1 from the release holes 110 to control the corrosion boundary accurately, so that a second sacrificial layer structure with a preset cross-sectional shape can be obtained, the phenomenon that the sacrificial layer material remains in the part where the diaphragm vibrates under the action of the sound wave does not exist, and the stress of the diaphragm along the release boundary of the second sacrificial layer is uniformly distributed when the diaphragm, the mechanical property of the MEMS microphone chip is improved, failure is avoided, and the service life of the MEMS microphone is prolonged.

In order to further improve the accuracy of controlling the corrosion boundary of the sacrificial layer material between the diaphragm and the back plate 1 when the corrosive liquid flows from the outermost hole a, the embodiment provides the following technical solutions:

alternatively, referring to fig. 1, the geometric centers of the plurality of outermost holes a enclose a circle on the back plate 1, and the center of the circle coincides with the center position a of the back plate 1.

Specifically, referring to fig. 2, a plurality of release holes 110 are uniformly distributed on the back plate 1 in a circumferential manner. Therefore, the corrosive liquid flows into the sacrificial layer material between the diaphragm and the back plate 1 from the sound holes 10 and the release holes 110, respectively, the areas and shapes of the grooves formed after the corrosive liquid flowing into each release hole 110 corrodes the sacrificial layer material are the same, can be communicated with a groove formed after the corrosion liquid flowing into the sound hole 10 corrodes the sacrificial layer material, therefore, the sacrificial layer material between the diaphragm and the back plate 1 can be etched to form a groove with a preset shape, so that the cross-sectional shape of the second sacrificial layer structure conforms to the preset shape, the phenomenon that the sacrificial layer material remains in the part of the diaphragm which vibrates under the action of sound waves is avoided, when the vibrating diaphragm vibrates under the action of sound waves, the stress of the vibrating diaphragm on the releasing boundary of the second sacrificial layer is uniformly distributed, the mechanical performance of the MEMS microphone chip is improved, failure does not occur, and the service life of the MEMS microphone is prolonged.

Optionally, the maximum open area of the other types of holes is N times the minimum open area of the outermost periphery of holes a, where N is greater than or equal to 5 and less than or equal to 25; accordingly, the number of outermost holes a is 50 or more. The outermost hole a is a release hole 110, the hole b includes a plurality of sound holes, and the hole c includes a plurality of release holes 102.

In the above technical solution, the second sacrificial layer structure with the preset cross-sectional shape can be obtained by simultaneously flowing the corrosive liquid into the release hole 110, the air release hole 102 and the sound hole 10. The sound holes 10 and the air release holes 102 on the back plate 1 can allow sound waves to pass through and transmit to the diaphragm, the diaphragm deforms under the action of the sound waves, air in the air gap is compressed, and the sound holes on the back plate can allow the air to flow out, so that damping is reduced. When the diaphragm vibrates due to the sound waves, the air flow between the diaphragm and the back plate 1 can be exhausted through the sound holes 10 and the air release holes 102 distributed on the back plate 1, and the process is a source of noise. The back plate is provided with the sound hole 10 and the air release hole 102, and a certain opening area is ensured, so that air between the vibrating diaphragm and the back plate 1 can be smoothly discharged through the sound hole 10, noise is weakened, and the signal-to-noise ratio is improved. However, if the area of the opening on the back plate 1 is too large, the sensitivity of the MEMS microphone chip may be reduced because the damping of the back plate 1 to air is too small in the process that the air between the diaphragm and the back plate 1 can be smoothly discharged through the sound hole 10 and the air release hole 102. Therefore, in order to ensure that the damping of the back plate 1 to the air is not so small as to affect the sensitivity of the MEMS microphone chip during the vibration of the diaphragm, it is necessary to ensure that the opening area of the release hole 110 is within the preset threshold. Specifically, this can be achieved by setting the open area of each of the release holes 110 and the number of the release holes 110.

Alternatively, referring to fig. 2, the maximum open area of the relief holes and the sound holes 10 is N times the minimum open area of the release holes 110, where N is greater than or equal to 5 and less than or equal to 25.

Specifically, when the opening areas of the plurality of release holes 110 are within the preset threshold, the minimum opening area of the release holes 110 is too large to be larger than the minimum opening area 1/5 of the air release hole and the sound hole 10, on one hand, in the process that the air between the diaphragm and the back plate 1 can be smoothly discharged through the release holes 110, the damping of the release holes 110 to the air is too small, so that the sensitivity of the MEMS microphone chip is reduced, on the other hand, when the corrosive liquid flows into the sacrificial layer material between the diaphragm and the back plate 1 from the release holes 110, the control of the corrosion boundary is not accurate, so that the second sacrificial layer structure with the preset cross-sectional shape cannot be obtained. The minimum open area of the release holes 110 is too small to be smaller than 1/25, which is the minimum open area of the discharge holes and the sound holes 10, and the number of the release holes 110 needs to be set too much, resulting in an increased difficulty in the forming process of the release holes 110. Therefore, the maximum open area of the discharge hole and the sound hole 10 is N times the minimum open area of the discharge hole 110, wherein, when N is greater than or equal to 5 and less than or equal to 25, the damping of the air by the release holes 110 is too small in the process of avoiding the air between the diaphragm and the back plate 1 from being discharged, on the basis of reducing the sensitivity of the MEMS microphone chip, the corrosion liquid flows into the sacrificial layer material between the diaphragm and the back plate 1 from the release hole 110, the corrosion boundary is accurately controlled, the second sacrificial layer structure with the preset cross section shape can be obtained, the phenomenon that the sacrificial layer material is remained at the part of the diaphragm which needs to vibrate under the action of sound waves does not exist, when the vibrating diaphragm vibrates under the action of sound waves, the stress of the vibrating diaphragm on the releasing boundary of the second sacrificial layer is uniformly distributed, the mechanical performance of the MEMS microphone chip is improved, failure does not occur, and the service life of the MEMS microphone is prolonged. At the same time, the formation process of the release hole 110 is not difficult.

Optionally, the number of the release holes 110 is greater than or equal to 50.

Specifically, when the opening area of the plurality of release holes 110 is within the preset threshold, the number of the release holes 110 is greater than or equal to 50, so as to avoid that the damping of the release holes 110 to the air is too small in the process that the air between the diaphragm and the back plate 1 can be smoothly discharged through the release holes 110, on the basis of reducing the sensitivity of the MEMS microphone chip, the etching liquid flows into the etching boundary of the sacrificial material between the diaphragm and the back plate from the release hole 110, the second sacrificial layer structure with the preset cross section shape can be obtained accurately, the phenomenon that the sacrificial layer material remains in the part of the diaphragm which is vibrated under the action of sound waves is avoided, when the vibrating diaphragm vibrates under the action of sound waves, the stress of the vibrating diaphragm on the releasing boundary of the second sacrificial layer is uniformly distributed, the mechanical performance of the MEMS microphone chip is improved, failure does not occur, and the service life of the MEMS microphone is prolonged.

Alternatively, the cross-sectional shape of the outermost peripheral hole a includes a circle or a regular polygon. The outermost hole a is a release hole 110, the hole b includes a plurality of sound holes, and the hole c includes a plurality of release holes 102.

In the above technical solution, the second sacrificial layer structure with the preset cross-sectional shape can be obtained by simultaneously flowing the corrosive liquid into the release hole 110, the air release hole 102 and the sound hole 10. The cross-sectional shapes of the release holes 110 are different, so that the corrosive liquid flows from the release holes 110 into the different shapes of the corrosive boundaries of the sacrificial layer material between the diaphragm and the back plate 1. In order to obtain the second sacrificial layer structure of controllable corrosion boundary, the embodiment of the utility model provides a following technical scheme: the cross-sectional shape of the release hole 110 includes a circle or a regular polygon.

Fig. 2 exemplarily shows only a case where the cross-sectional shape of the release hole 110 is a circle. It should be noted that the cross-sectional shape of the release hole 110 is circular, which is better achieved in terms of process.

Optionally, the outermost peripheral hole a includes a first straight hole or a Y-shaped hole. The Y-shaped holes comprise positive Y-shaped holes or reverse Y-shaped holes. The Y-shaped hole comprises a T-shaped hole and a second straight hole which are communicated, and the diameter of the T-shaped hole is increased along the direction of the second straight hole pointing to the T-shaped hole.

In the above technical solution, the second sacrificial layer structure with the preset cross-sectional shape can be obtained by simultaneously flowing the corrosive liquid into the release hole 110, the air release hole 102 and the sound hole 10. The longitudinal sectional shape of the release hole 110 also affects the performance of the MEMS microphone chip.

Fig. 3 is a schematic cross-sectional structure view of the releasing hole 110C-C ' in fig. 2 according to an embodiment of the present invention, fig. 4 is a schematic cross-sectional structure view of the releasing hole 110C-C ' in fig. 2 according to another embodiment of the present invention, and fig. 5 is a schematic cross-sectional structure view of the releasing hole 110C-C ' in fig. 2 according to another embodiment of the present invention.

Alternatively, referring to fig. 3, 4 and 5, the release hole 110 includes a first straight hole 111 or a Y-shaped hole 112.

Specifically, the longitudinal sectional shape of the first straight hole 111 in fig. 3 is a rectangle. The flowing speed of the corrosive liquid in the first straight hole 111 is uniform, that is, the corrosive liquid flows in from the first straight hole 111 uniformly, so that the sacrificial layer material between the vibrating diaphragm and the back plate 1 is corroded at a uniform corrosion speed, and the control accuracy of the corrosion boundary of the sacrificial layer material between the vibrating diaphragm and the back plate 1 is improved.

The Y-shaped hole 112 in fig. 4 and 5 has a Y-shaped longitudinal sectional shape. Among them, the Y-shaped hole 112 shown in fig. 4 is a positive Y-shaped hole. The Y-shaped hole 112 shown in fig. 5 is an inverted Y-shaped hole.

Alternatively, referring to fig. 4 and 5, the Y-shaped hole 112 includes a T-shaped hole 112a and a second straight hole 112b communicating with each other, and the diameter of the T-shaped hole 112a increases as the second straight hole 112b points in the direction of the T-shaped hole 112 a.

It should be noted that the Y-shaped hole 112 shown in fig. 4 is a positive Y-shaped hole, and the etching solution first passes through the large-aperture T-shaped hole 112a, so that the etching solution can more easily enter the release hole 110, and then erodes the sacrificial layer material between the diaphragm and the back plate 1 at a uniform flow rate through the second straight hole 112b, thereby improving the accuracy of controlling the erosion boundary of the sacrificial layer material between the diaphragm and the back plate 1. The Y-shaped hole 112 shown in fig. 5 is an inverted Y-shaped hole, and when the air in the diaphragm and the backplate 1 is discharged through the inverted Y-shaped hole, the air passes through the large-aperture T-shaped hole 112a first and then passes through the small-aperture second straight hole 112b, so that the damping of the backplate 1 on the air is properly and uniformly increased, the response frequency of the MEMS microphone chip is smoothed, and the sensitivity of the device is improved.

The cross-sectional shape of the first straight hole 111 may be a circle or a regular polygon. Since the first through hole 111 having a circular cross-sectional shape is relatively simple in manufacturing process, the cross-sectional shape of the first through hole 111 may be circular in this embodiment. Optionally, the pore diameter of the first straight pore 111 is greater than or equal to 2 micrometers and less than or equal to 3 micrometers.

Specifically, the aperture of the first straight hole 111 is greater than or equal to 2 microns, and is less than or equal to 3 microns, between 1/10 and 1/5 of the aperture of one sound hole 10, and is much smaller than the aperture of one sound hole 10, in the process of avoiding that the air between the vibrating diaphragm and the back plate 1 can be smoothly discharged through the first straight hole 111, the damping of the air by the first straight hole 111 is too small, so that the sensitivity of the MEMS microphone chip is reduced, meanwhile, the corrosive liquid flows into the corrosion boundary of the sacrificial layer material between the vibrating diaphragm and the back plate 1 from the first straight hole 111, and the difficulty of the forming process of the first straight hole 111 is not great. The aperture of the first straight hole 111 is smaller than 2 microns, so that the difficulty of the forming process of the first straight hole 111 is high; the aperture of the first straight hole 111 is larger than 3 micrometers, so that on one hand, in the process that air between the diaphragm and the back plate 1 can be smoothly discharged through the first straight hole 111, the sensitivity of the MEMS microphone chip is reduced due to too small damping of the first straight hole 111 to the air, and on the other hand, corrosive liquid flows into the first straight hole 111 to control the corrosion boundary of the sacrificial material between the diaphragm and the back plate inaccurately.

Alternatively, referring to fig. 4 and 5, the maximum pore size d1 of the T-shaped pores 112a is greater than or equal to 3 microns and less than or equal to 4 microns; and/or the minimum pore diameter d2 of the T-shaped pores 112a is greater than or equal to 1 micron and less than or equal to 3 microns.

Specifically, the maximum aperture d1 of the T-shaped hole 112a is larger than 4 μm, which causes the amount of the corrosive liquid entering the T-shaped hole 112a instantly to be too large and the flow rate to be too high, on one hand, the corrosive liquid may flow into the release hole 110 to control the corrosion boundary of the sacrificial material between the diaphragm and the back plate inaccurately, and on the other hand, the air between the diaphragm and the back plate 1 may be discharged through the first straight hole 111 smoothly, and on the other hand, the sensitivity of the MEMS microphone chip may be reduced due to the too small damping of the first straight hole 111 to the air. The maximum aperture d1 of the T-shaped hole 112a is smaller than 3 μm, which makes the forming process of the T-shaped hole 112a more difficult and causes the flow rate of the etching solution in the T-shaped hole 112a to be too small, resulting in too long etching time.

The minimum aperture d2 of the T-shaped hole 112a is larger than 3 micrometers, which may cause the sensitivity of the MEMS microphone chip to decrease due to too small damping of the first straight hole 111 to the air in the process that the air between the diaphragm and the back plate 1 may be smoothly discharged through the first straight hole 111; the smallest diameter d2 of the T-shaped hole 112a is smaller than 1 μm, which results in too small flow rate of the etching solution in the T-shaped hole 112a, resulting in too long etching time and making the process of forming the T-shaped hole 112a difficult.

With a certain thickness of the back plate 1, the depth of the second straight hole 112b also affects the performance of the MEMS microphone chip.

Alternatively, referring to fig. 4 and 5, the back plate 1 includes a lower back plate 1b and an upper back plate 1a located above the lower back plate, and the depth of the second straight hole 112b is greater than or equal to zero and less than the thickness of the lower back plate 1 b.

Specifically, the back plate 1 includes a lower back plate 1b and an upper back plate 1 a. The lower back plate 1b is illustratively silicon nitride, and the upper back plate 1a is illustratively polysilicon. Silicon nitride may increase the mechanical strength of the back plate 1. The upper back plate 1a is used for leading out the electric signal on the back plate.

Fig. 6 is a schematic cross-sectional view of another release hole 110C-C 'in fig. 2 according to an embodiment of the present invention, and fig. 7 is a schematic cross-sectional view of another release hole 110C-C' in fig. 1 according to an embodiment of the present invention. Referring to fig. 6 and 7, the depth of the second straight hole 112b is equal to zero, and the longitudinal sectional shape of the Y-shaped hole 112 is a regular trapezoid in fig. 6 or an inverted trapezoid in fig. 7. Specifically, when the etching liquid flows in the regular trapezoid shown in fig. 6, the etching liquid more easily enters. When the air in the diaphragm and the back plate 1 is exhausted through the inverted trapezoid hole shown in fig. 7, the damping of the back plate 1 to the air is properly increased, so that the response frequency of the MEMS microphone chip becomes gentle, and the sensitivity of the device is improved.

Referring to fig. 4 and 5, the depth of the second straight hole 112b is greater than zero, the Y-shaped hole 112 shown in fig. 4 is a positive Y-shaped hole, the etching solution first passes through the large-diameter T-shaped hole 112a, so that the etching solution can more easily enter the release hole 110, and then the sacrificial layer material between the diaphragm and the back plate 1 is etched at a uniform flow rate through the second straight hole 112b, thereby improving the accuracy of controlling the etching boundary of the sacrificial layer material between the diaphragm and the back plate 1. The Y-shaped hole 112 shown in fig. 5 is an inverted Y-shaped hole, and when the air in the diaphragm and the backplate 1 is discharged through the inverted Y-shaped hole, the air passes through the large-aperture T-shaped hole 112a first and then passes through the small-aperture second straight hole 112b, so that the damping of the backplate 1 on the air is properly and uniformly increased, the response frequency of the MEMS microphone chip is smoothed, and the sensitivity of the device is improved.

However, when the depth of the second straight hole 112b is greater than the thickness of the lower back plate, the aperture of the second straight hole 112b is smaller, which affects the overall flow rate of the etching solution, resulting in too small overall flow rate, and thus the etching time of the etching solution on the sacrificial layer material is too long.

In the packaging process and the using process of the MEMS microphone chip, if the environment changes, for example, when the microphone chip falls off, the working performance of the MEMS microphone chip can be affected by over-large or under-small air pressure in the microphone cavity. The utility model discloses disappointing hole 102's main effect is the unnecessary gas that is used for discharging in the MEMS microphone chip cavity, adjusts the atmospheric pressure in the MEMS microphone chip cavity, and then strengthens MEMS microphone chip's anti falling performance.

For the atmospheric pressure in the quick adjustment MEMS microphone chip cavity, the embodiment of the utility model provides a following technical scheme: referring to fig. 2, the opening area of the relief hole 102 is larger than that of the sound hole 10. Specifically, the air release hole 102 is matched with the air release hole on the diaphragm, when the air pressure is increased instantly, the opening area of the air release hole 102 is large, and redundant air in the cavity of the MEMS microphone chip can be rapidly discharged to adjust the air pressure in the cavity of the MEMS microphone chip, so that the anti-falling performance of the MEMS microphone chip is enhanced.

The embodiment of the utility model provides a micro electro mechanical system microphone is still provided. Fig. 8 is a schematic structural diagram of a mems microphone according to an embodiment of the present invention. Fig. 9 is a schematic structural diagram of another mems microphone according to an embodiment of the present invention. Referring to fig. 8 and 9, the mems microphone includes: a micro-electro-mechanical system microphone chip 3, an application specific integrated circuit chip 4, a base 5 and a housing; the micro-electro-mechanical system microphone chip 3 and the special integrated circuit chip 4 are fixed on the base, and the micro-electro-mechanical system microphone chip 3 and the special integrated circuit chip 4 are electrically connected; the mems microphone chip 3 includes the back plate 1 according to any of the above technical solutions. Note that the microphone shown in fig. 8 is a back-entry microphone, and the sound inlet D is provided in the microphone base. Fig. 9 shows the microphone as a front sound microphone with the sound inlet E on the housing 6. Both these structures of microphones can use the backplate 1 mentioned in the above technical solutions.

The utility model provides a microelectromechanical system microphone includes back polar plate 1 that mentions among the above-mentioned technical scheme, consequently, the embodiment of the utility model provides a microelectromechanical system microphone also possesses the beneficial effect that describes among the above-mentioned technical scheme, and here is no longer repeated.

Fig. 10 is a schematic structural diagram of a mems microphone chip according to an embodiment of the present invention. Optionally, referring to fig. 10, the mems microphone chip 3 includes a substrate 30, a first sacrificial layer structure 31, a second sacrificial layer structure 32, a diaphragm 2, and a back plate 1;

the substrate 30 includes a cavity 300 and a support 301 surrounding the cavity 300; a first sacrificial layer structure 31 on the support portion 301; the second sacrificial layer structure 32 is located between the diaphragm 2 and the back plate 1, and a space surrounded by the back plate 1, the second sacrificial layer structure 32 and the diaphragm 2 is an air gap.

It should be noted that the present embodiment does not limit the positional relationship between the back plate 1 and the diaphragm 2. Fig. 10 shows by way of example that the backplate 1 is situated on the diaphragm 2. Specifically, the diaphragm 2 is located on the surface of the first sacrificial layer structure 31 on the side far away from the substrate 30; a second sacrificial layer structure 32 located on a surface of the diaphragm 2 on a side away from the first sacrificial layer structure 31; the back plate 1 is located on the surface of the second sacrificial layer structure 32 on the side away from the diaphragm 2, the sound hole 10, the air release hole 102 and the release hole 110 on the back plate 1 are used for placing corrosive liquid for forming the second sacrificial layer structure 32, and a space surrounded by the back plate 1, the second sacrificial layer structure 32 and the diaphragm 2 is an air gap 33. Illustratively, the area of the groove etched by the etching solution of the second sacrificial layer structure 32 is larger than the area of the groove etched by the etching solution of the first sacrificial layer structure 31.

The utility model provides a micro electro mechanical system microphone chip 3, back polar plate 1 including mentioning in the above-mentioned technical scheme, consequently, the embodiment of the utility model provides a micro electro mechanical system microphone chip also possesses the beneficial effect that describes among the above-mentioned technical scheme, and here is no longer repeated.

Alternatively, referring to fig. 10, the surface of the back plate 1 adjacent to the diaphragm is provided with an adhesion preventing structure 11. The diaphragm 2 can be effectively prevented from returning to the balance position because the van der waals force between the diaphragm 2 and the back plate 1 is greater than the restoring force of the vibrating part of the diaphragm 2 in the vibrating process of the diaphragm 2.

Optionally, the mems microphone chip 3 further includes a through hole 12 and a metal pad 13, the through hole 12 penetrates through the back plate 1 and the diaphragm 2, and the metal pad 13 is located at the bottom of the through hole 12 and electrically connected to the diaphragm 2, and is configured to lead out an electrical signal of the diaphragm 2. The back plate 1 is also provided with a metal pad for drawing an electric signal of the back plate 1, which is not shown in the drawing. The design of sound hole 10 on back plate 1 is in order to transmit the sound wave to vibrating diaphragm 2 through sound hole 10 and disappointing hole 102, and vibrating diaphragm 2 is receiving the acoustic wave effect and taking place deformation for the distance between vibrating diaphragm 2 and back plate 1 changes, changes capacitance capacity and voltage, and application specific integrated circuit chip 4 is connected with back plate 1 and the metal pad electricity that vibrating diaphragm 2 draws forth the signal of telecommunication, changes the change of capacitance into the change of voltage signal and carries out the output.

Alternatively, referring to fig. 10, the height of the air gap 33 is greater than or equal to 1.5 microns and less than or equal to 3 microns.

The sound wave passes through the sound hole 10 and the air release hole 102 on the back plate 1, and passes through the air gap 33 to deform the diaphragm, so that the capacitance between the diaphragm and the back plate 1 changes. The height of the air gap 33 is too small, less than 1.5 μm, which on the one hand limits the vibration range of the diaphragm 2 and on the other hand causes the diaphragm and the backplate 1 to contact the backplate 1 during vibration, which does not allow the complete conversion of the sound signal into an electrical signal. When the height of the air gap 33 is too large and larger than 3 micrometers, the capacitance value between the diaphragm 2 and the back plate 1 changes too little, which affects the sensitivity of the device.

Alternatively, referring to fig. 10, the diaphragm 2 includes at least one relief hole 21, the number of relief holes 21 in the diaphragm 2 is the same as the number of relief holes 102 in the back plate 1, and an orthographic projection of the relief hole 102 in each back plate 1 on the substrate 30 covers an orthographic projection of the relief hole 21 in the diaphragm 2 on the substrate 30.

Specifically, the air release hole 102 in the back plate 1 is matched with the air release hole 21 on the diaphragm 2, when the air pressure is increased instantly, the aperture of the air release hole 102 in the back plate 1 is large, and redundant air in the cavity of the MEMS microphone chip can be rapidly discharged to adjust the air pressure in the cavity of the MEMS microphone chip, so that the anti-falling performance of the MEMS microphone chip is enhanced.

Alternatively, referring to fig. 10, the cross-section of the second sacrificial layer structure 32 includes a circular groove, and on the surface of the second sacrificial layer structure 21 contacting the back plate 1, a diameter d3 including the circular groove is M times a shortest distance d4 from the outermost hole a to the second sacrificial layer structure 32, where M is greater than or equal to 10 and less than or equal to 20. In fig. 10, the outermost hole a is taken as an example of the release hole 110.

Specifically, the diameter d3 including the circular grooves is too small as a multiple of the shortest distance d4 from the release holes 110 to the second sacrificial layer structure 32, and M is less than 10, i.e., the area of the grooves formed after the etching liquid flowing in from each release hole 110 corrodes the sacrificial layer material is too large, resulting in too long etching time.

The diameter d3 including the circular groove is too large as a multiple of the shortest distance d4 from the release holes 110 to the second sacrificial layer structure 32, M is larger than 20, that is, the area of the groove formed after the corrosion of the sacrificial layer material by the corrosive liquid flowing in from each release hole 110 is too small, and since the open area of the release holes 110 is limited, the groove formed after the corrosion of the sacrificial layer material by the corrosive liquid flowing in from each release hole 110 and the groove formed after the corrosion of the sacrificial layer material by the corrosive liquid flowing in from the acoustic hole 10 are difficult to communicate with each other, resulting in the shape of the cross section of the second sacrificial layer structure 32 not conforming to the preset shape.

Specifically, referring to fig. 10, on the surface of the second sacrificial layer structure 32 in contact with the back plate 1, the shortest distance d4 from the outermost peripheral hole a to the second sacrificial layer structure 32 is greater than or equal to 8 micrometers, and less than or equal to 15 micrometers. In fig. 10, the outermost hole a is taken as an example of the release hole 110. The shortest distance d4 from the release hole 110 to the second sacrificial layer structure 32 is greater than or equal to 8 microns and less than or equal to 15 microns. The shortest distance d4 from the release holes 110 to the second sacrificial layer structure 32 is too large, and larger than 15 μm, the area of the groove formed after the etching of the sacrificial layer material by the etching liquid flowing from each release hole 110 is too large, resulting in too long etching time. When the shortest distance d4 between the release holes 110 and the second sacrificial layer structure 32 is too small and smaller than 8 μm, that is, the area of the groove formed after the corrosion solution flows in from each release hole 110 corrodes the sacrificial layer material is too small, and since the open area of the release holes 110 is limited, the groove formed after the corrosion solution flows in from each release hole 110 corrodes the sacrificial layer material is difficult to communicate with the groove formed after the corrosion solution flows in from the acoustic holes 10 corrodes the sacrificial layer material, so that the cross-sectional shape of the second sacrificial layer structure 32 does not conform to the predetermined shape.

It should be noted that the foregoing is only a preferred embodiment of the present invention and the technical principles applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail with reference to the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the scope of the present invention.

Claims

1. A backplate, comprising: at least three different areas of apertures, with the outermost apertures surrounding other types of apertures.

2. The backplate of claim 1, wherein the outermost periphery apertures comprise a plurality of release apertures and the other types of apertures comprise a plurality of sound apertures and a plurality of bleed apertures.

3. The backplate of claim 1, wherein each of the outermost peripheral holes is a predetermined distance from the central position of the backplate, and a plurality of the outermost peripheral holes are uniformly spaced within a predetermined threshold from the central position of the backplate.

4. The backplate of claim 3, wherein the geometric center of the outermost aperture forms a circle on the backplate having a center coincident with the center of the backplate.

5. The backplate of claim 1, wherein the other types of holes have a maximum open area that is N times a minimum open area of the outermost peripheral holes, wherein N is greater than or equal to 5 and less than or equal to 25;

accordingly, the number of outermost peripheral holes is greater than or equal to 50.

6. The backplate of claim 1, wherein the outermost peripheral aperture comprises a circular or regular polygon cross-sectional shape.

7. The backplate of claim 1, wherein the outermost peripheral aperture comprises a first straight aperture or a Y-shaped aperture.

8. The backplate of claim 7, wherein the Y-shaped aperture comprises a positive Y-shaped aperture or an inverted Y-shaped aperture.

9. The backplate of claim 7, wherein the Y-shaped holes comprise a T-shaped hole and a second straight hole which are connected, and the diameter of the T-shaped hole increases as the second straight hole points in the direction of the T-shaped hole.

10. The backplate of claim 7, wherein the first straight holes have a pore size greater than or equal to 2 microns and less than or equal to 3 microns.

11. The backplate of claim 9, wherein the T-shaped holes have a maximum pore size greater than or equal to 3 microns and less than or equal to 4 microns; and/or the minimum pore diameter of the T-shaped pores is greater than or equal to 1 micrometer and less than or equal to 3 micrometers.

12. The backplate of claim 9, wherein the backplate comprises a lower backplate and an upper backplate above the lower backplate, and the depth of the second straight holes is greater than or equal to zero and less than the thickness of the lower backplate.

13. The backplate of claim 2, wherein the relief holes have an area greater than the area of the sound holes.

14. A mems microphone, comprising:

the mems microphone chip comprising a backplate according to any one of claims 1 to 13.

15. The mems microphone of claim 14, wherein the mems microphone chip comprises a substrate, a diaphragm, a backplate, a first sacrificial layer structure, and a second sacrificial layer structure;

the substrate comprises a cavity and a support part surrounding the cavity;

the first sacrificial layer structure is positioned on the supporting part;

the second sacrificial layer structure is located between the vibrating diaphragm and the back plate, and a space surrounded by the back plate, the second sacrificial layer structure and the vibrating diaphragm is an air gap.

16. The mems microphone of claim 15, wherein the air gap has a height greater than or equal to 1.5 microns and less than or equal to 3 microns.

17. The mems microphone of claim 15, wherein the diaphragm comprises at least one air-bleed hole, the number of the air-bleed holes in the diaphragm is the same as the number of the air-bleed holes in the back plate, and an orthographic projection of each air-bleed hole in the back plate on the substrate covers an orthographic projection of the air-bleed hole in the diaphragm on the substrate.

18. The mems microphone of claim 15, wherein the cross-section of the second sacrificial layer structure comprises a circular groove having a diameter M times a shortest distance from an outermost peripheral hole in the backplate to the second sacrificial layer structure on a surface of the second sacrificial layer structure in contact with the backplate, wherein M is greater than or equal to 10 and less than or equal to 20.

19. The mems microphone of claim 18, wherein a shortest distance from the outermost peripheral hole to the second sacrificial layer structure on a surface of the second sacrificial layer structure in contact with the backplate is greater than or equal to 8 microns and less than or equal to 15 microns.