MEMS microphone

Abstract

The present invention provides a MEMS microphone, comprising: a substrate provided with a back cavity passing therethrough; a back plate fixed to the substrate; and a diaphragm located between the back plate and the substrate along the thickness direction of the substrate, the diaphragm comprising a vibrating body, and the vibrating body comprising an inner region, an outer region, and a plurality of connecting portions distributed at intervals along the circumferential direction of the diaphragm, wherein the inner region is suspended above the back cavity, the outer region is fixedly connected to the substrate, the connecting portions are suspended above the substrate, two ends of each connecting portion are respectively fixedly connected to the inner region and the outer region along the radial direction of the diaphragm, and the width of the connecting portions gradually decreases along a direction from the inner region to the outer region. In the MEMS microphone of the present invention, the structural rigidity of the connecting portions can be reduced, increasing the amplitude of the diaphragm, thereby improving the sensitivity of the MEMS microphone; in addition, stress on the connecting portions can also be transferred to the substrate, uniformly distributing the stress on the connecting portions, reducing the maximum stress on the connecting portions under a given load, thereby improving the structural stability of the microphone.

Description

MEMS microphone Technical Field

[0001] This invention relates to the field of MEMS microphone technology, and more particularly to a MEMS microphone. Background Technology

[0002] MEMS (Micro-Electro Mechanical System) microphones have advantages such as small size, high temperature resistance, and easy mounting, and are now widely used in mobile phones, tablets, and smart wearable devices. MEMS microphones have a diaphragm, which usually adopts a cantilever beam structure. That is, the diaphragm includes an inner region and an outer region that are spaced apart. The inner region is suspended above the substrate, and the outer region is fixedly connected to the substrate. The inner region is connected to the outer region through the connecting part of the cantilever beam structure. Technical issues

[0003] In existing MEMS microphones, the stiffness of the connector is reduced and the sensitivity of the diaphragm is improved by decreasing the width of the connector or increasing the spacing between adjacent connectors. However, under high loads, this structure can lead to high stress concentration at the inner end of the connector, causing connector failure. Therefore, it is necessary to provide a new MEMS microphone to solve the above problems. Technical solutions

[0004] The purpose of this invention is to provide a MEMS microphone that can balance the stress on the connection part and improve the stress uniformity.

[0005] The technical solution of the present invention is as follows: A MEMS microphone is provided, comprising: a substrate having a through-hole cavity; a back plate fixed to the substrate; and a diaphragm located between the back plate and the substrate along the thickness direction of the substrate. The diaphragm includes a vibrating body, the vibrating body including an inner region, an outer region, and a plurality of connecting portions spaced circumferentially along the diaphragm. The inner region is suspended above the back cavity, and the outer region is fixedly connected to the substrate. The connecting portions are suspended above the substrate, and along the radial direction of the diaphragm, both ends of the connecting portions are fixedly connected to the inner region and the outer region, respectively. The width of the connecting portions gradually decreases along the direction from the inner region to the outer region.

[0006] In one possible design, the width of any part of the connection portion satisfies 5μm~20μm.

[0007] In one possible design, the connecting part includes a first end connected to the inner region and a second end connected to the outer region; the width of the first end is D1, and the width of the second end is D2, where 1.1≤D1:D2≤1.3.

[0008] In one possible design, multiple connecting portions are arranged at equal angular intervals around the axis of the base.

[0009] In one possible design, the number of connecting parts is 60 to 100.

[0010] In one possible design, the outer region is fixedly connected to the substrate via a first anchoring structure; along the thickness direction of the substrate, the two side surfaces of the first anchoring structure are fixedly connected to the outer region and the substrate, respectively.

[0011] In one possible design, a gap exists between the first anchoring structure and the connection portion along the radial direction of the diaphragm, so that at least a portion of the outer region can be suspended above the substrate.

[0012] In one possible design, the diaphragm further includes multiple independent fixing parts, which are fixedly connected to the substrate and / or the back plate; along the circumference of the diaphragm, each of the independent fixing parts is located between two adjacent connecting parts; the independent fixing parts are spaced apart from the connecting parts, the inner region, and the outer region.

[0013] In one possible design, the independent fixing part is fixedly connected to the base and / or the back plate via a second anchoring structure.

[0014] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit the invention. Beneficial effects

[0015] Compared to a structure with a connector of uniform width, this design reduces the amount of material required for the connector, which helps lower its stiffness and increases the diaphragm amplitude, thereby improving the sensitivity of the MEMS microphone. Furthermore, the connection between the connector and the inner region is the widest, while the connection with the outer region is the narrowest. This disperses stress to the outer region, reducing internal stress at the first end and lowering the maximum stress on the connector under a given load, preventing damage to the first end due to excessive stress. Therefore, the MEMS microphone structure provided in this application can improve the diaphragm's sensitivity while balancing the stress on various parts of the connector, avoiding stress concentration. This allows the connector to withstand higher loads, improving its structural stability and thus enhancing the overall structural stability of the MEMS microphone. This improves the reliability of the MEMS microphone during drops or impacts, ultimately extending its lifespan. Attached Figure Description

[0016] Figure 1 is a schematic diagram of the structure of the MEMS microphone provided by the present invention in a specific embodiment;

[0017] Figure 2 is a schematic cross-sectional view of the MEMS microphone in Figure 1 along the AA' direction;

[0018] Figure 3 is a schematic diagram of the MEMS microphone in Figure 2 when it is equipped with a backplate;

[0019] Figure 4 is a partial structural schematic diagram of the vibrating main body in Figure 1;

[0020] Figure 5 is a schematic cross-sectional view of the MEMS microphone in Figure 1 along the BB' direction.

[0021] Figure label:

[0022] 1-Base; 10-Back cavity; 2-Back plate; 3-Diaphragm; 3a-Vibration body; 3b-Independent fixing part; 31-Inner region; 32-Outer region; 33-Connecting part; 331-First end; 332-Second end; 4-First anchoring structure; 5-Second anchoring structure; 6-Gap.

[0023] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit the invention. The best embodiment of the present invention

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “said,” and “the” as used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0026] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0027] It should be noted that the directional terms such as "upper," "lower," "left," and "right" described in the embodiments of this application are used to describe the angles shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when referring to an element being connected "upper" or "lower" to another element, it can mean not only being directly connected to the other element "upper" or "lower," but also being indirectly connected to the other element "upper" or "lower" through an intermediate element.

[0028] Embodiments of the present invention provide a MEMS microphone that can be applied to electronic devices such as mobile phones, smartwatches, tablets, laptops, virtual reality devices, or walkie-talkies. Specifically, the MEMS microphone can be a condenser microphone, a piezoelectric microphone, or an optical microphone.

[0029] As shown in Figures 1 to 3, the MEMS microphone includes at least a substrate 1, a backplate 2, and a diaphragm 3. The substrate 1 has a through-hole cavity 10. The backplate 2 is fixed to the substrate 1 and spaced apart from the diaphragm 3, forming a capacitor system with the diaphragm 3. The diaphragm 3 is located between the backplate 2 and the substrate 1 along the thickness direction of the substrate 1. When the diaphragm 3 vibrates, the distance between it and the backplate 2 changes, resulting in a change in capacitance. The backplate 2 can specifically be the structure shown in Figure 3, or other structures. This embodiment does not limit the structure of the backplate 2 or the connection method between the backplate 2 and the substrate 1.

[0030] As shown in Figures 2 and 4, the diaphragm 3 includes a vibrating body 3a, which comprises an inner region 31, an outer region 32, and multiple connecting portions 33 spaced circumferentially along the diaphragm 3. The inner region 31 is suspended above the back cavity 10, meaning that the projection of the inner region 31 onto the base 1 along the thickness direction Z of the base 1 lies within the back cavity 10. The outer region 32 is fixedly connected to the base 1, and the connecting portions 33 are suspended above the base 1. Along the radial direction X of the diaphragm 3, both ends of the connecting portions 33 are fixedly connected to the inner region 31 and the outer region 32, respectively. In this embodiment, the inner region 31 of the diaphragm 3 is completely suspended above the substrate 1 and is connected to the substrate 1 only through the outer region 32. The inner region 31 and the outer region 32 are connected by multiple spaced connecting parts 33, and the connecting parts 33 are also suspended above the substrate 1. This structure is beneficial to improving the flexibility of the diaphragm 3, thereby increasing its amplitude and increasing the displacement of the diaphragm 3 under the action of external sound pressure. This is beneficial to improving the sensitivity of the MEMS microphone and the accuracy of the MEMS microphone in converting sound signals into electrical signals.

[0031] The connecting portion 33 includes a first end 331 connected to the inner region 31 and a second end 332 connected to the outer region 32. The width of the connecting portion 33 gradually decreases along the direction from the first end 331 to the second end 332. First, compared to a structure with a connecting portion 33 of equal width, the above structure can reduce the amount of material required for the connecting portion 33, which is beneficial to reducing the stiffness of the connecting portion 33, thereby increasing the amplitude of the diaphragm 3 and thus improving the sensitivity of the MEMS microphone. Moreover, compared to a structure where the second end 332 is wider and the first end 331 is narrower, in this embodiment, the width of the connecting portion 33 connected to the inner region 31 (first end 331) is the largest and the width of the connecting portion 33 connected to the outer region 32 (second end 332) is the smallest. This can disperse stress to the outer region 32, thereby reducing the internal stress at the first end 331, reducing the maximum stress value of the connecting portion 33 under a given load, and preventing the first end 331 from being damaged due to excessive stress.

[0032] Therefore, by setting the connection part 33 to a structure in which the width gradually decreases along the direction from the first end 331 to the second end 332, the sensitivity of the diaphragm 3 can be improved while balancing the stress on each part of the connection part 33, avoiding stress concentration, so that the connection part 33 can withstand higher loads, improving the structural stability of the connection part 33, thereby improving the structural stability of the MEMS microphone, improving the reliability of the MEMS microphone during drops or impacts, and thus improving the service life of the MEMS microphone.

[0033] Specifically, the width of the connecting portion 33 can vary uniformly along the direction from the first end 331 to the second end 332, so that the uniformly varied structure has a better stress dispersion effect compared with the stepped or other non-uniformly varied structures.

[0034] In one specific embodiment, the width of the first end 331 is D1, and the width of the second end 332 is D2. D1 and D2 should satisfy: 1.1 ≤ D1:D2 ≤ 1.3. Specifically, D1:D2 can be 1.1, 1.12, 1.15, 1.18, 1.2, 1.22, 1.25, 1.27, or 1.3, or other values ​​within the above range. This embodiment does not impose any restrictions on this. When the width D1 of the first end 331 and the width D2 of the second end 332 satisfy the above range, the structural rationality of the connecting part 33 can be ensured, avoiding both excessively large widths of the first end 331 and excessively small widths of the second end 332.

[0035] Specifically, the width of any part of the connecting portion 33 satisfies 5μm~20μm, specifically 5μm, 6μm, 8μm, 10μm, 12μm, 15μm, 17μm, 19μm or 20μm, or other values ​​within the above range; this embodiment does not impose any restrictions on this. Therefore, the width D1 of the first end 331 should be less than 20μm, and the width D2 of the second end 332 should be greater than 5μm. When the width of any part of the connecting portion 33 satisfies the above range, it can ensure that the connecting portion 33 as a whole has sufficient structural strength, and it can also avoid the reduction of the amplitude of the diaphragm 3 due to the excessive area of ​​the connecting portion 33.

[0036] In one specific embodiment, multiple connecting portions 33 are arranged at equal angular intervals around the axis of the substrate 1, that is, the multiple connecting portions 33 are evenly distributed in the circumferential direction of the substrate 1, thereby achieving the effect of uniformly dispersing stress in the circumferential direction of the substrate 1. The uniform distribution of multiple connecting portions 33 in the circumferential direction of the substrate 1 also helps to improve the connection stability between the inner region 31 and the outer region 32, thereby improving the structural stability of the diaphragm 3. Alternatively, the multiple connecting portions 33 may also be unevenly distributed in the circumferential direction of the substrate 1, and this embodiment does not limit this.

[0037] The number of connecting parts 33 can be 60 to 100, specifically 60, 65, 70, 75, 80, 85, 90, 95, or 100, or other values ​​within the above range. This embodiment does not impose any limitation on this. When the number of connecting parts 33 meets the above range, the stress on a single connecting part 33 can be reduced, and the structural stability of the connecting part 33 can be improved. This is beneficial to improving the effect of dispersing stress from the inner region 31 to the outer region 32, and also beneficial to improving the connection stability between the inner region 31 and the outer region 32, thereby improving the structural stability of the diaphragm 3.

[0038] In one specific embodiment, as shown in Figure 3, the outer region 32 is fixedly connected to the substrate 1 via a first anchoring structure 4. Along the thickness direction Z of the substrate 1, the two side surfaces of the first anchoring structure 4 are fixedly connected to the outer region 32 and the substrate 1, respectively. Specifically, the first anchoring structure 4 can be an oxide layer, ensuring a strong connection between the outer region 32 and the substrate 1, providing support for the diaphragm 3, thereby improving the stability of the diaphragm 3 under high loads and extending its reliability and service life. Of course, the first anchoring structure 4 can also be other forms of connection structure; this embodiment does not limit this.

[0039] Specifically, as shown in Figure 2, there is a gap 6 between the first anchoring structure 4 and the connecting part 33 along the radial X of the diaphragm 3, so that at least a part of the outer region 32 can be suspended on the base 1, that is, the second end 332 does not contact the first anchoring structure 4, which can reduce the risk of stress concentration at the second end 332.

[0040] In one specific embodiment, as shown in Figures 1 and 5, the diaphragm 3 further includes multiple independent fixing parts 3b. These independent fixing parts 3b are fixedly connected to the base 1 and / or the back plate 2. Specifically, along the circumference of the diaphragm 3, each independent fixing part 3b is located between two adjacent connecting parts 33. The independent fixing parts 3b, connecting parts 33, inner region 31, and outer region 32 are all spaced apart, meaning the independent fixing parts 3b are independent of the vibrating body 3a and do not vibrate up and down with it. By providing independent fixing parts 3b, the internal and external pressure balance of the diaphragm 3 can be maintained without affecting the vibration effect of the vibrating body 3a, thereby improving the mechanical stability of the diaphragm 3 and extending the service life of the MEMS microphone. The independent fixing parts 3b are fixedly connected to the base 1 and / or the back plate 2 through a second anchoring structure 5. The second anchoring structure 5 can also be the same oxide layer as the first anchoring structure 4, or it can be other forms of connection structure; this embodiment does not limit this.

[0041] In this embodiment, the independent fixing part 3b can be formed by etching the diaphragm 3. Specifically, taking the independent fixing part 3b and the substrate 1 as fixedly connected by the second anchoring structure 5 as an example: firstly, an oxide layer can be deposited on the substrate 1 to form the first anchoring structure 4 and the second anchoring structure 5, and then the diaphragm 3 can be set on the oxide layer. Then, the diaphragm 3 can be etched according to the preset pattern to form the independent vibration body 3a and the independent fixing part 3b.

[0042] The above description is merely an embodiment of the present invention. It should be noted that those skilled in the art can make improvements without departing from the inventive concept of the present invention, but these improvements all fall within the protection scope of the present invention.

Claims

1. A MEMS microphone, characterized in that, include: The base has a through-cavity; Back plate, fixed to the base; A diaphragm is located between the back plate and the substrate along the thickness direction of the substrate. The diaphragm includes a vibration body, which includes an inner region, an outer region, and a plurality of connecting portions spaced apart circumferentially along the diaphragm. The inner region is suspended above the back cavity, and the outer region is fixedly connected to the substrate. The connecting part is suspended above the substrate and along the radial direction of the diaphragm, with its two ends fixedly connected to the inner region and the outer region, respectively. The width of the connecting portion gradually decreases along the direction from the inner region to the outer region.

2. The MEMS microphone according to claim 1, characterized in that, The width of any part of the connection portion is between 5μm and 20μm.

3. The MEMS microphone according to claim 1, characterized in that, The connecting portion includes a first end connected to the inner region and a second end connected to the outer region; The width of the first end is D1, and the width of the second end is D2, where 1.1 ≤ D1:D2 ≤ 1.

3.

4. The MEMS microphone according to claim 1, characterized in that, The plurality of connecting portions are arranged at equal angular intervals around the axis of the base.

5. The MEMS microphone according to claim 1, characterized in that, The number of connecting parts is 60 to 100.

6. The MEMS microphone according to claim 1, characterized in that, The outer region is fixedly connected to the base via a first anchoring structure; Along the thickness direction of the substrate, the two side surfaces of the first anchoring structure are fixedly connected to the outer region and the substrate, respectively.

7. The MEMS microphone according to claim 6, characterized in that, Along the radial direction of the diaphragm, there is a gap between the first anchoring structure and the connecting portion, so that at least a portion of the outer region can be suspended on the substrate.

8. The MEMS microphone according to any one of claims 1-7, characterized in that, The diaphragm also includes multiple independent fixing parts, which are fixedly connected to the substrate and / or the back plate; Along the circumference of the diaphragm, each of the independent fixing parts is located between two adjacent connecting parts; The independent fixing part is spaced apart from the connecting part, the inner region, and the outer region.

9. The MEMS microphone according to claim 8, characterized in that, The independent fixing part is fixedly connected to the base through a second anchoring structure; Alternatively, the independent fixing part is fixedly connected to the back plate through a second anchoring structure; Alternatively, the independent fixing parts are respectively fixedly connected to the base and the back plate via a second anchoring structure.

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