阅读说明：本技术 Mems麦克风及其背极板 (MEMS microphone and back plate thereof ) 是由 吕婷 于 2021-08-06 设计创作，主要内容包括：本发明提供一种MEMS麦克风及其背极板,所述背极板包括：支撑背板,设置有中部区,所述中部区分为第一开孔区及第二开孔区,所述第一开孔区设置有若干贯穿所述支撑背板的第一进声孔,所述第二开孔区设置有若干贯穿所述支撑背板的第二进声孔,所述第一进声孔的孔径大于所述第二进声孔的孔径；所述第二开孔区的边缘外侧设置有凹槽,所述凹槽贯穿所述支撑背板；背极,位于所述支撑背板的下表面；电极,设置在所述凹槽表面以及所述支撑背板上表面的部分区域,用于传输所述背极中的电信号；背极板焊盘,设置在所述支撑背板的上表面,并与所述电极连接。本发明的MEMS麦克风及其背极板可以降低电噪声,提高电信号的输出效率。(The invention provides an MEMS microphone and a back plate thereof, wherein the back plate comprises: the support back plate is provided with a middle area, the middle area is divided into a first opening area and a second opening area, the first opening area is provided with a plurality of first sound inlet holes penetrating through the support back plate, the second opening area is provided with a plurality of second sound inlet holes penetrating through the support back plate, and the aperture of each first sound inlet hole is larger than that of each second sound inlet hole; a groove is arranged on the outer side of the edge of the second opening area and penetrates through the support back plate; the back electrode is positioned on the lower surface of the support back plate; the electrode is arranged on the surface of the groove and partial area of the upper surface of the supporting back plate and is used for transmitting the electric signal in the back pole; and the back plate welding pad is arranged on the upper surface of the support back plate and is connected with the electrode. The MEMS microphone and the back plate thereof can reduce electric noise and improve the output efficiency of electric signals.)

1. A MEMS microphone backplate, the backplate comprising:

the supporting back plate comprises a first part and a second part, the first part and the second part are integrally connected, the second part is used for supporting the first part, a middle area is arranged in the middle area of the first part, the middle area is divided into a first opening area and a second opening area, the first opening area is provided with a plurality of first sound inlet holes penetrating through the supporting back plate, the second opening area is provided with a plurality of second sound inlet holes penetrating through the supporting back plate, and the aperture of each first sound inlet hole is larger than that of each second sound inlet hole; a groove is arranged on the outer side of the edge of the second opening area and penetrates through the support back plate;

the back pole is positioned on the lower surface of the supporting back plate, and the first sound inlet hole and the second sound inlet hole are arranged corresponding to the supporting back plate;

the electrode is arranged on the surface of the groove and partial area of the upper surface of the supporting back plate and is used for transmitting the electric signal in the back pole;

and the back plate welding pad is arranged on the upper surface of the support back plate and is connected with the electrode.

2. The MEMS microphone backplate of claim 1, wherein: the shape of the middle area is selected from one of a circle, a rounded rectangle and a regular polygon.

3. The MEMS microphone backplate of claim 1, wherein: the shape of the second opening area is selected from one of a sector, a rounded trapezoid and a parallelogram.

4. The MEMS microphone backplate of claim 1, wherein: the ratio of the area of the second opening area to the area of the middle area is 5-15%.

5. The MEMS microphone backplate of claim 1, wherein: the ratio of the area of the middle region to the area of the upper surface of the support back plate ranges from 70% to 90%.

6. The MEMS microphone backplate of claim 1, wherein: the first sound inlet holes are arranged at equal intervals, and the numerical range of the interval distance is 5-20 mu m; the plurality of second sound inlet holes are arranged at equal intervals, and the numerical range of the interval distance is 10-40 mu m.

7. The MEMS microphone backplate of claim 1, wherein: the shape of the first sound inlet hole is selected from one of circle, ellipse and polygon; the shape of the second sound inlet hole is selected from one of a circle, an ellipse and a polygon.

8. The MEMS microphone backplate of claim 7, wherein: the first sound inlet hole and the second sound inlet hole are both circular, the aperture range of the first sound inlet hole is 5-30 mu m, and the aperture range of the second sound inlet hole is 2.5-15 mu m.

9. The MEMS microphone backplate of claim 1, wherein: the area of the back electrode, which is in contact with the electrode at the bottom of the groove, is a conductive area, and the conductive area and the second opening area are in contact with the middle of the outer edge of the second opening area.

10. A MEMS microphone, comprising:

a substrate forming a support structure and provided with an opening;

the vibrating diaphragm is arranged on the opening of the substrate in a spanning mode;

the MEMS microphone backplate of any one of claims 1-9, positioned above the substrate and the diaphragm with a predetermined spacing therebetween.

Technical Field

The invention relates to the technical field of microphones, in particular to an MEMS (micro-electromechanical systems) microphone and a back plate thereof.

Background

With the rapid development of wireless communication, the requirements of people on the communication quality are higher and higher, and the microphone industry is in a vigorous development period. The microphone is an energy conversion device for converting a sound signal into an electric signal, and is widely applied to the fields of mobile electronic equipment, intelligent sound control equipment and the like. In recent years, the conventional electret condenser microphone has been replaced with the MEMS microphone because the matching work is relatively troublesome.

The MEMS Microphone is called a Micro-Electro-Mechanical-System Microphone (Micro-phone), the performance of the MEMS Microphone is stable at different temperatures, and the sensitivity of the MEMS Microphone cannot be influenced by temperature, vibration, humidity and time, so that the MEMS Microphone can be widely applied to various complex environments. The MEMS microphone adopts a capacitive principle and comprises a diaphragm capable of vibrating up and down and a fixed back plate, wherein the back plate has excellent rigidity and is etched with a sound inlet hole to allow air to circulate without deviation, and the diaphragm can bend along with sound waves, so that the distance between the diaphragm and the back plate is changed, and capacitance change is generated accordingly. The ASIC chip connected with the MEMS microphone can amplify and convert the weak capacitance change into an electric signal and output the electric signal. However, the structural design of the acoustic holes in the backplate in prior art microphones results in more electrical noise in the electrical signal.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention is directed to a MEMS microphone and a backplate thereof, which are used to solve the problem of the MEMS microphone in the prior art that the noise of the electrical signal is more.

To achieve the above and other related objects, the present invention provides a MEMS microphone backplate, comprising:

the supporting back plate comprises a first part and a second part, the first part and the second part are integrally connected, the second part is used for supporting the first part, a middle area is arranged in the middle area of the first part, the middle area is divided into a first opening area and a second opening area, the first opening area is provided with a plurality of first sound inlet holes penetrating through the supporting back plate, the second opening area is provided with a plurality of second sound inlet holes penetrating through the supporting back plate, and the aperture of each first sound inlet hole is larger than that of each second sound inlet hole; a groove is arranged on the outer side of the edge of the second opening area and penetrates through the support back plate;

the back pole is positioned on the lower surface of the supporting back plate, and the first sound inlet hole and the second sound inlet hole are arranged corresponding to the supporting back plate;

the electrode is arranged on the surface of the groove and partial area of the upper surface of the supporting back plate and is used for transmitting the electric signal in the back pole;

and the back plate welding pad is arranged on the upper surface of the support back plate and is connected with the electrode.

Optionally, the shape of the middle region is selected from one of a circle, a rounded rectangle, and a regular polygon.

Optionally, the shape of the second open region is selected from one of a sector, a rounded trapezoid and a parallelogram.

Optionally, the ratio of the area of the second open area to the area of the middle area ranges from 5% to 15%.

Optionally, the ratio of the area of the middle region to the area of the upper surface of the support backplate is in the range of 70% to 90%.

Optionally, a plurality of the first sound inlet holes are arranged at equal intervals, and the numerical range of the interval distance is 5-20 μm; the plurality of second sound inlet holes are arranged at equal intervals, and the numerical range of the interval distance is 10-40 mu m.

Optionally, the shape of the first sound inlet hole is selected from one of a circle, an ellipse and a polygon; the shape of the second sound inlet hole is selected from one of a circle, an ellipse and a polygon.

Furthermore, the first sound inlet hole and the second sound inlet hole are both circular, the aperture range of the first sound inlet hole is 5-30 μm, and the aperture range of the second sound inlet hole is 2.5-15 μm.

Optionally, a region of the back electrode contacting the electrode at the bottom of the groove is a conductive region, and the conductive region and the second opening region contact the middle of the outer edge of the second opening region.

The present invention also provides a MEMS microphone, including:

a substrate forming a support structure and provided with an opening;

the vibrating diaphragm is arranged on the opening of the substrate in a spanning mode;

in any of the above technical solutions, the MEMS microphone back plate is located above the substrate and the diaphragm, and has a preset interval with the diaphragm.

As described above, the MEMS microphone and the back plate thereof according to the present invention have the following advantageous effects: under the condition that the sound wave is not influenced and is transmitted to the vibrating diaphragm through the back plate, the hole diameter of the sound inlet hole near the electric signal transmission area in the back plate is reduced, the conductive area of the back plate for transmitting the electric signals in the back plate is increased, electric noise is reduced, loss of the electric signals of the back plate in the transmission process is reduced, and the output efficiency of the electric signals is improved.

Drawings

Fig. 1 is a schematic top view of a back plate in the prior art.

Fig. 2 is a schematic front sectional view of a MEMS microphone in the prior art.

FIG. 3 is a schematic top view of a first back plate according to an embodiment of the present invention

Fig. 4 is a schematic top view of a second back plate according to an embodiment of the present invention.

Fig. 5 is a schematic top view of a third back plate according to an embodiment of the present invention.

Fig. 6 is a schematic front cross-sectional view illustrating a MEMS microphone according to an embodiment of the present invention.

Description of the element reference numerals

10 support backboard

101 first part

1011 middle region

1011a first opening region

1011b second opening region

102 second part

103 groove

20 first sound inlet hole

21 second sound inlet hole

30 back pole

301 conductive region

40 electrodes

50 back plate pad

60 stop block

70 substrate

80 diaphragm

90 fold structure

100 air escape hole

110 support

120 cavity

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and although the drawings only show the components related to the present invention and are not drawn according to the number, shape and size of the components in actual implementation, the form, quantity, position relationship and proportion of the components in actual implementation can be changed freely on the premise of implementing the technical solution of the present invention, and the layout form of the components may be more complicated.

Fig. 1 is a top view of a conventional backplate arrangement of a MEMS microphone. The back plate is provided with a plurality of first sound inlet holes 20, and the first sound inlet holes 20 penetrate through the back plate and are uniformly distributed in a preset area (middle area) 1011 of the back plate. The first sound inlet holes 20 have the same aperture, and the first sound inlet holes 20 are equally spaced.

Referring to fig. 2, a back plate and a diaphragm 80 form a parallel plate capacitor structure, and when the diaphragm 80 senses an external audio sound pressure signal, a distance between the diaphragm 80 and the back plate changes, a capacitance capacity changes, and the capacitance change is converted into a voltage signal change through an integrated circuit chip and is output. The conductive region 301 is a region of the back electrode 30 contacting the electrode 40 at the bottom of the groove 103, and is a portion for transmitting an electrical signal, and the portion is electrically connected to the electrode 40 in the groove 103, and the electrode 40 extending on the upper surface of the support back plate 10 is connected to the back electrode pad 50, so that an electrical signal is transmitted to the back electrode pad 50. One side of the conductive region 301 is located at the edge of the central region 1011, meeting at a in fig. 1. A large amount of charge in the back pole 30 will accumulate at a, resulting in increased noise in the electrical signal. The inventor has found that this is because the occupation of the first sound inlet hole 20 results in a small conductive area for transmitting the electric signal in the back electrode 30, and as the current density increases, the movement degree of the particles becomes more severe, and the noise in the electric signal also increases. Based on this analysis, the inventors considered reducing electrical noise by increasing the conductive area at a, and the specific embodiments are as follows.

As shown in fig. 3 and fig. 6, the present invention provides a MEMS microphone backplate, the backplate includes a supporting backplate 10, a backplate 30, an electrode 40 and a backplate pad 50, wherein the supporting backplate 10 includes a first portion 101 and a second portion 102, the first portion 101 is integrally connected to the second portion 102, the second portion 102 is used to support the first portion 101, a middle region 1011 is disposed in a middle region of the first portion 101, the middle region 1011 is divided into a first opening region 1011a and a second opening region 1011b, the first opening region 1011a is provided with a plurality of first sound holes 20 penetrating through the supporting backplate 10, the second opening region 1011b is provided with a plurality of second sound holes 21 penetrating through the supporting backplate 10, and an aperture of the first sound holes 20 is larger than an aperture of the second sound holes 21; a groove 103 is formed on the outer side of the edge of the second opening area 1011b, and the groove 103 penetrates through the support backboard 10; the back electrode 30 is located on the lower surface of the support backplate 10, and the first sound inlet hole 20 and the second sound inlet hole 21 are arranged corresponding to the support backplate 10; the electrode 40 is arranged on the surface of the groove 103 and a partial area of the upper surface of the support back plate 10 and is used for transmitting the electric signal in the back pole 30; the back plate pad 50 is disposed on the upper surface of the support back plate 10 and connected to the electrode 40. It should be noted that the aperture in the back electrode 30 on the lower surface of the second opening 1011b is significantly reduced, and the conductive area of the back electrode 30 is significantly increased, so that the charges are not easily gathered near the conductive region 301, thereby reducing the noise in the electrical signal and improving the transmission efficiency of the electrical signal. .

As an example, the shape of the central region 1011 may be a shape common to existing MEMS microphones, such as a circle (as shown in fig. 3), a rounded rectangle (as shown in fig. 4), or a regular polygon (as shown in fig. 5).

As an example, the shape of the second perforated area 1011b may be selected from one of a sector (as shown in fig. 3), a rounded trapezoid (as shown in fig. 4), and a parallelogram (as shown in fig. 5).

It should be noted that, in other embodiments, the shape of the central region 1011 and the shape of the second opening region 1011b may be selected from other shapes as required, and the protection scope of the present invention should not be limited too much.

As shown in fig. 3, in the back plate provided by the embodiment of the present invention, the central region 1011 is circular, and the second opening region 1011b is fan-shaped.

As shown in fig. 4, for a back plate provided in an embodiment of the present invention, the central region 1011 is in a shape of a rounded quadrangle, and the second opening region 1011b is in a shape of a rounded trapezoid.

As shown in fig. 5, for a back plate provided by an embodiment of the present invention, the shape of the middle region 1011 is a regular hexagon, and the shape of the second opening region 1011b is a parallelogram

As an example, the ratio of the area of the second opening area 1011b to the area of the middle area 1011 is in the range of 5% to 15%, and this ratio range not only can prevent the transmission of electrical signals from being affected and reduce electrical noise, but also can prevent sound waves from being greatly obstructed in the process of passing through the back plate, so that the MEMS microphone can receive normal sound signals.

As an example, the area of the middle region 1011 is appropriate to ensure that the sound wave can smoothly pass through the back plate without affecting the normal operation of the device. The ratio of the area of the middle region 1011 to the area of the upper surface of the support backplate 10 is in the range of 70-90%. Preferably, the ratio of the area 1011 of the central region to the area of the support backplate 10 is 80%.

As an example, the first sound inlet holes 20 are arranged at equal intervals, and the interval distance is in the range of 5 μm to 20 μm, and preferably, the interval distance of the first sound inlet holes 20 is 10 μm; the plurality of second sound inlet holes 21 are arranged at equal intervals, and the interval distance between the plurality of second sound inlet holes 21 is 10 μm-40 μm, and preferably, the interval distance between the plurality of second sound inlet holes 21 is 25 μm.

As an example, the shape of the first sound inlet hole 20 is selected from one of a circle, an ellipse, and a polygon; the shape of the second sound inlet hole 21 may also be selected from one of a circle, an ellipse, and a polygon.

It should be noted that, in other embodiments, the shapes of the first sound inlet 20 and the second sound inlet 21 may also be selected from other shapes as needed, as long as the proper size is satisfied, and the sound wave can smoothly pass through, and the protection scope of the present invention should not be limited too much here.

As an example, the first sound inlet hole 20 and the second sound inlet hole 21 are both circular, the aperture range of the first sound inlet hole 20 is 5 μm to 30 μm, and the aperture range of the second sound inlet hole 21 is 2.5 μm to 15 μm, so as to ensure that sound waves are not influenced to be transmitted into the microphone through the first sound inlet hole 20 and the second sound inlet hole 21.

As an example, as shown in fig. 3, the groove 103 is near the middle of the outer edge of the second perforated area 1011b, and one side of the corresponding conductive area 301 contacts the second sound inlet aperture area 1011b at a position b, which may be the middle of the outer edge of the second perforated area 1011 b. In this way, it is ensured that the intersection b of the conductive region 301 and the second sound hole region 1011b is not occupied by the first sound inlet hole 20 (large sound inlet hole) and only occupied by the second sound inlet hole 21 (small sound inlet hole), so that the conductive area in the back electrode 30 is increased, no charge is accumulated, the electrical noise is reduced, and the output efficiency of the electrical signal is improved.

As shown in fig. 6, the present invention further provides a MEMS microphone, wherein the MEMS microphone backplate according to any one of the above technical solutions is applied to the MEMS microphone, the MEMS microphone includes a substrate 70, a diaphragm 80, and the MEMS microphone backplate according to any one of the above technical solutions, wherein the substrate 70 forms a supporting structure and is provided with an opening; the diaphragm 80 spans the opening of the substrate 70 and is connected to the substrate 70; the back plate is located above the substrate 70 and the diaphragm 80, and a preset interval exists between the back plate and the diaphragm 80. In addition, conventional structures in the MEMS microphone, such as the blocking block 60, the corrugated structure 90, the air release hole 100, the bracket 110, the cavity 120, etc., may be further included, and will not be described in detail herein.

As an example, the second portion 102 of the support backplate 10 is located on the substrate 70 and contacts the substrate 70, and the second portion 102 supports the first portion 101 such that the first portion 101 crosses over the diaphragm 80.

As an example, the working steps of the MEMS microphone of the present invention include:

s1, transmitting sound waves to the diaphragm 80 through a plurality of first sound inlet holes 20 and a plurality of second sound inlet holes 21 of the MEMS microphone back plate;

s2, bending the diaphragm 80 along with the sound wave, so that the distance between the diaphragm 80 and the back plate is changed, and capacitance change is generated;

and S3, amplifying the capacitance change by the special integrated circuit chip connected with the MEMS microphone, and converting the capacitance change into an electric signal to be output.

In summary, the present invention provides an MEMS microphone back plate, where the back plate includes a support back plate, a back plate, an electrode, and a back plate pad, where the support back plate includes a first portion and a second portion, the first portion and the second portion are integrally connected, the second portion is used to support the first portion, a middle area of the first portion is provided with a middle area, the middle area is divided into a first opening area and a second opening area, the first opening area is provided with a plurality of first sound inlet holes penetrating through the support back plate, the second opening area is provided with a plurality of second sound inlet holes penetrating through the support back plate, and a pore diameter of the first sound inlet holes is larger than a pore diameter of the second sound inlet holes; a groove is arranged on the outer side of the edge of the second opening area and penetrates through the support back plate; the back pole is positioned on the lower surface of the support back plate, and the first sound inlet hole and the second sound inlet hole are arranged corresponding to the support back plate; the electrodes are arranged on the surface of the groove and partial areas of the upper surface of the supporting back plate and are used for transmitting electric signals in the back pole; the back plate welding pad is arranged on the upper surface of the support back plate and is connected with the electrode. The MEMS microphone and the back plate thereof have the following beneficial effects: the aperture of the sound inlet hole near the electric signal transmission area in the back plate is reduced, and the conductive area of the back plate for transmitting the electric signal in the back plate is increased, so that the electric noise is reduced, the loss of the electric signal of the back plate in the transmission process is reduced, and the output efficiency of the electric signal is improved. Therefore, the present invention effectively overcomes the disadvantages of the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.