MEMS chip and MEMS microphone

Abstract

The utility model discloses an MEMS chip and an MEMS microphone, and the MEMS chip comprises a substrate, a waterproof layer, a hydrophobic layer, and an MEMS transducer structure. The waterproof layer and the MEMS transducer structure are sequentially arranged on the surface of one side of the substrate in a stacked mode in the direction away from the substrate. A back cavity is formed in the substrate in the stacking direction in a penetrating mode, a plurality of air holes are formed in the portion, exposed out of the back cavity, of the waterproof layer at intervals, and at least the portion, exposed out of the back cavity, of the waterproof layer is wrapped with a hydrophobic layer. According to the invention, the assembly process is reduced, the cost is reduced, and the dustproof and waterproof consistency is improved.

Description

Technical Field

[0001] This utility model relates to the field of acoustic and electronic technology, and in particular to a MEMS chip and a MEMS microphone. Background Technology

[0002] The waterproof and breathable design of sensors can achieve both waterproof and breathable functions. It is widely used in automobiles, consumer electronics and other fields to protect devices from moisture. It is of great significance for improving the durability, reliability and user experience of sensors.

[0003] Currently, sensors used in consumer electronics, such as MEMS microphones, generally employ traditional dustproof mesh structures for waterproofing and breathability. These dustproof mesh structures are primarily composed of polymer materials and are assembled to the microphone's inlet using adhesive. This process not only increases the number of steps but also raises costs. Furthermore, the irregular microstructure of the organic polymer dustproof mesh results in inconsistent dustproof and waterproof performance. Utility Model Content

[0004] Embodiments of this utility model provide a MEMS chip and a MEMS microphone to save processes, reduce costs, and improve dustproof and waterproof consistency.

[0005] To solve the above-mentioned technical problems, the embodiments of this utility model disclose the following technical solutions:

[0006] In a first aspect, this application provides a MEMS chip, including a substrate, a waterproof layer, a hydrophobic layer, and a MEMS transducer structure;

[0007] The waterproof layer and the MEMS transducer structure are sequentially stacked on one side surface of the substrate along the direction away from the substrate;

[0008] The substrate has a through-cavity along the stacking direction, and the waterproof layer has multiple vent holes spaced apart in the portion exposed to the back cavity. At least the portion of the waterproof layer exposed to the back cavity is covered with a hydrophobic layer.

[0009] Furthermore, the MEMS chip also includes a first sacrificial layer disposed between the substrate and the waterproof layer.

[0010] Furthermore, the MEMS transducer structure includes a backplate, a diaphragm, a second sacrificial layer, and a third sacrificial layer;

[0011] The second sacrificial layer, the diaphragm, the third sacrificial layer, and the back plate are stacked sequentially along the stacking direction, with the second sacrificial layer placed on the waterproof layer.

[0012] The second sacrificial layer has a first cavity that extends along the stacking direction, and the third sacrificial layer has a second cavity that extends along the stacking direction. The projection of the first cavity onto the diaphragm and the projection of the second cavity onto the diaphragm overlap.

[0013] Furthermore, the backplate includes an insulating layer and a conductive layer. The insulating layer is disposed on the third sacrificial layer, and the conductive layer is disposed on the insulating layer. The portion of the backplate exposed to the second cavity is provided with multiple through holes at intervals.

[0014] Furthermore, the MEMS transducer structure also includes a first electrical connection terminal and a second electrical connection terminal, the first electrical connection terminal being electrically connected to the diaphragm, and the second electrical connection terminal being electrically connected to the conductive layer.

[0015] Furthermore, the diameter of the vent holes ranges from 2μm to 5μm, and the spacing between the vent holes ranges from 2μm to 5μm.

[0016] Furthermore, the acoustic impedance of the waterproof layer is less than or equal to 600 Rayles.

[0017] Furthermore, the waterproof layer is one of silicon, polycrystalline silicon, or silicon nitride, and the thickness of the waterproof layer ranges from 2μm to 20μm.

[0018] Secondly, this application also provides a MEMS microphone, including any of the above-mentioned MEMS chips and ASIC chips, wherein the ASIC chip is disposed on a PCB board, and the MEMS chip and the ASIC chip, as well as the ASIC chip and the PCB board, are connected by electrical connection lines.

[0019] Furthermore, the MEMS microphone also includes a metal housing, which is mounted on a PCB board to house the MEMS chip and the ASIC chip.

[0020] One of the above technical solutions has the following advantages or beneficial effects: The MEMS chip achieves dust and water resistance through a waterproof layer between the substrate and the MEMS transducer structure. This waterproof layer is integrated into the MEMS chip during chip fabrication, rather than being installed at the microphone inlet using adhesive, thus reducing assembly steps and lowering costs. Furthermore, compared to traditional dustproof mesh structures composed of organic polymer materials, the porous waterproof layer formed using semiconductor technology improves the consistency of dust and water resistance. Attached Figure Description

[0021] The technical solution and other beneficial effects of this utility model will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0022] Figure 1 This is a schematic diagram of the MEMS chip provided in the embodiments of this application;

[0023] Figure 2 This is one of the schematic diagrams showing the arrangement of the vent holes provided in the embodiments of this application;

[0024] Figure 3 This is the second schematic diagram of the arrangement of the vent holes provided in the embodiments of this application;

[0025] Figure 4 This is a schematic diagram of the structure of the MEMS microphone provided in the embodiments of this application;

[0026] Figure 5 This is a noise comparison diagram provided in the embodiments of this application.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1. MEMS chip; 2. ASIC chip; 3. PCB board; 4. Metal casing; 5. Electrical connection wire; 10. Substrate; 20. First sacrificial layer; 30. Waterproof layer; 40. MEMS transducer structure; 101. Back cavity; 301. Vent hole; 302. Hydrophobic layer; 401. Second sacrificial layer; 402. Diaphragm; 403. Third sacrificial layer; 404. Back plate; 405. First electrical connection terminal; 406. Second electrical connection terminal; 4021. First cavity; 4022. Second cavity; 4041. Insulating layer; 4042. Conductive layer; 4043. Through hole. Detailed Implementation

[0029] To make the objectives, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described in this specification are merely for explaining the present utility model and are not intended to limit the present utility model.

[0030] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0031] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0032] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0033] To make the objectives, features and advantages of this utility model more apparent and understandable, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] This application provides a MEMS chip 1, referring to... Figure 1The MEMS chip 1 includes a substrate 10, a waterproof layer 30, a hydrophobic layer 302, and a MEMS transducer structure 40. The waterproof layer 30 and the MEMS transducer structure 40 are sequentially stacked on one side surface of the substrate 10 along a direction away from the substrate 10. Specifically, the MEMS chip 1 has a first direction, a second direction, and a third direction, which intersect each other and are perpendicular. The stacking direction is set along the third direction, and along the third direction, the substrate 10, the first sacrificial layer 20, the waterproof layer 30, and the MEMS transducer structure 40 are sequentially arranged.

[0035] The substrate 10 has a through-cavity 101 extending along the stacking direction. The portion of the waterproof layer 30 exposed in the through-cavity 101 has multiple vent holes 301 spaced apart. These vent holes 301 prevent a predetermined amount of impurities from entering while allowing a predetermined amount of air to pass through. The impurities include liquids, solid particles, and so on. Furthermore, the air entering the MEMS transducer structure 40 through the vent holes 301 causes changes in the MEMS transducer structure 40, generating relevant electrical signals.

[0036] In addition, the surface of the waterproof layer 30 is also covered with a hydrophobic layer 302. Specifically, at least the surface of the waterproof layer 30 exposed to the back cavity 101 is covered with a hydrophobic layer 302. This hydrophobic layer 302 can further effectively prevent moisture from penetrating the MEMS transducer structure 40, thereby improving the reliability and durability of the MEMS transducer structure 40. The hydrophobic layer 302 can be a fluorinated polymer, silicon-based material, nanomaterial, etc., and it can be applied to the waterproof layer 30 using processes such as SAM (Self-Assembled Monolayer) or metal plating. Furthermore, to ensure the acoustic performance of the MEMS transducer structure 40, the thickness of the hydrophobic layer 302 is less than 250 nm.

[0037] Furthermore, the vent holes 301 on the waterproof layer 30 can be as follows: Figure 2 The independently spaced arrangement shown can also be as follows: Figure 3 The diagram shows multiple vent holes 301 arranged in series. The diameter of each vent hole 301 ranges from 2μm to 5μm, and can be 2μm, 3μm, 4μm, etc. The spacing between the vent holes 301 ranges from 2μm to 5μm. The acoustic impedance of the waterproof layer 30 is less than or equal to 600 Rayles, resulting in low acoustic impedance that meets the requirements for microphone use. The waterproof layer 30 is made of one of silicon-based materials such as silicon, polycrystalline silicon, or silicon nitride. The thickness of the waterproof layer 30 can range from 2μm to 20μm, ensuring the supporting strength of the waterproof layer 30.

[0038] The MEMS chip 1 provided in this embodiment achieves dust and water resistance through a waterproof layer 30 between the substrate 10 and the MEMS transducer structure 40. This waterproof layer 30 is integrated into the MEMS chip 1 during fabrication, rather than being installed at the microphone inlet using adhesive, thus reducing assembly steps and lowering costs. Furthermore, compared to traditional dustproof mesh structures composed of organic polymer materials, the waterproof layer 30 with permeable pores formed using semiconductor technology improves the consistency of dust and water resistance.

[0039] In some embodiments of this application, the MEMS chip 1 further includes a first sacrificial layer 20, which is disposed between the substrate 10 and the waterproof layer 30, and the first sacrificial layer 20 and the substrate 10 are connected along the stacking direction to form a back cavity 101. The first sacrificial layer 20 can be a commonly used sacrificial layer material such as silicon oxide, and the substrate 10 is made of silicon.

[0040] In some embodiments of this application, the MEMS transducer structure 40 includes a backplate 404, a diaphragm 402, a second sacrificial layer 401, and a third sacrificial layer 403. The second sacrificial layer 401, the diaphragm 402, the third sacrificial layer 403, and the backplate 404 are stacked sequentially along the stacking direction, and the second sacrificial layer 401 is disposed on the waterproof layer 30.

[0041] The second sacrificial layer 401 has a first cavity 4021 extending along the lamination direction, and the third sacrificial layer has a second cavity 4022 extending along the lamination direction. Along the lamination direction, the projections of the first cavity 4021 on the diaphragm 402 and the second cavity 4022 on the diaphragm 402 overlap. The projections of the first cavity 4021 on the waterproof layer 30 and the projections of the back cavity 101 on the waterproof layer 30 also overlap, which can be partial or complete overlap. A predetermined amount of air passes through the vent 301 and acts on the diaphragm 402, causing the diaphragm 402 to deform and thereby generate relevant electrical signals. The diaphragm 402 can deform within the first cavity 4021 and the second cavity 4022.

[0042] In addition, to further enhance waterproofing performance, a hydrophobic layer 302 is also wrapped around the surface of the waterproof layer 30 exposed in the first cavity 4021. Furthermore, the materials of the first sacrificial layer 20, the second sacrificial layer 401, and the third sacrificial layer 403 can be the same or different.

[0043] Furthermore, the backplate 404 includes an insulating layer 4041 and a conductive layer 4042. The insulating layer 4041 is disposed on the third sacrificial layer 403, and the conductive layer 4042 is disposed on the insulating layer 4041. The portion of the backplate 404 exposed to the second cavity 4022 is provided with a plurality of through holes 4043 at intervals. More specifically, both the insulating layer 4041 and the conductive layer 4042 are provided with a plurality of through holes 4043 at intervals, and the projections of the through holes 4043 on the insulating layer 4041 and the through holes 4043 on the conductive layer 4042 onto the diaphragm 402 along a third direction overlap. The through holes 4043 on the backplate 404 can realize stress release, air circulation, pressure balance, etc.

[0044] In addition, a plurality of protrusions are provided on the side of the insulating layer 4041 near the second cavity 4022. These protrusions can prevent the diaphragm 402 from sticking to the insulating layer 4041. The insulating layer 4041 can be silicon oxide, silicon nitride, etc., and the conductive layer 4042 can be polycrystalline silicon, metal thin film, metal alloy, etc. In this embodiment, the insulating layer 4041 is silicon nitride, and the conductive layer 4042 is polycrystalline silicon.

[0045] Furthermore, the MEMS transducer structure 40 also includes a first electrical connection terminal 405 and a second electrical connection terminal 406. The first electrical connection terminal 405 is electrically connected to the diaphragm 402, and the second electrical connection terminal 406 is electrically connected to the conductive layer 4042.

[0046] Specifically, the third sacrificial layer 403 has a through slot along the stacking direction. An insulating layer 4041 and a conductive layer 4042 are sequentially disposed on the surface of the third sacrificial layer 403 exposed in the slot. The first electrical connection terminal 405 is located in the slot and is electrically connected to the diaphragm 402.

[0047] like Figure 4 As shown, this application embodiment also provides a MEMS microphone, which includes the aforementioned MEMS chip 1 and ASIC chip 2. The ASIC chip 2 is disposed on a PCB board 3, and the MEMS chip 1 and ASIC chip 2, as well as the ASIC chip 2 and PCB board 3, are connected by electrical connection wires 5. Specifically, the ASIC chip 2 can be fixed to the PCB board 3 using hot melt adhesive or epoxy resin. A noise comparison is performed between the MEMS microphone provided in this application (i.e., a waterproof layer integrated MEMS microphone) and a waterproof layer assembled MEMS microphone. Figure 5 As shown in the noise spectrum curve, the MEMS microphone provided in this application has a comparable noise level and high consistency in waterproof and dustproof performance compared to existing MEMS microphones.

[0048] The MEMS microphone provided in this application embodiment does not require an additional waterproof layer 30 to be assembled at the sound inlet. The waterproof layer 30 integrated in the MEMS chip 1 can effectively achieve waterproof and dustproof protection, reducing assembly steps, lowering costs, and improving the consistency of waterproof and dustproof protection.

[0049] Furthermore, the MEMS microphone also includes a metal housing 4, which can be fixed on the PCB board 3 by soldering to accommodate the MEMS chip 1 and the ASIC chip 2.

[0050] The above embodiments merely illustrate several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A MEMS chip, comprising a substrate (10), a waterproof layer (30), a hydrophobic layer (302), and a MEMS transducer structure (40); The waterproof layer (30) and the MEMS transducer structure (40) are sequentially stacked on one side surface of the substrate (10) in a direction away from the substrate (10); The substrate (10) has a through cavity (101) along the stacking direction. The waterproof layer (30) exposed in the cavity (101) has a plurality of vent holes (301) at intervals. At least the part of the waterproof layer (30) exposed in the cavity (101) is covered with the hydrophobic layer (302).

2. The MEMS chip as described in claim 1, characterized in that, The MEMS chip further includes a first sacrificial layer (20), which is disposed between the substrate (10) and the waterproof layer (30).

3. The MEMS chip as described in claim 1, characterized in that, The MEMS transducer structure (40) includes a backplate (404), a diaphragm (402), a second sacrificial layer (401), and a third sacrificial layer (403); The second sacrificial layer (401), the diaphragm (402), the third sacrificial layer (403), and the back plate (404) are stacked sequentially along the stacking direction, and the second sacrificial layer (401) is disposed on the waterproof layer (30); The second sacrificial layer (401) has a first cavity (4021) extending along the stacking direction, and the third sacrificial layer (403) has a second cavity (4022) extending along the stacking direction. The projection of the first cavity (4021) on the diaphragm (402) and the projection of the second cavity (4022) on the diaphragm (402) overlap.

4. The MEMS chip as described in claim 3, characterized in that, The back plate (404) includes an insulating layer (4041) and a conductive layer (4042). The insulating layer (4041) is disposed on the third sacrificial layer (403), and the conductive layer (4042) is disposed on the insulating layer (4041). The portion of the back plate (404) exposed to the second cavity (4022) is provided with a plurality of through holes (4043) at intervals.

5. The MEMS chip as described in claim 4, characterized in that, The MEMS transducer structure (40) further includes a first electrical connection terminal (405) and a second electrical connection terminal (406), wherein the first electrical connection terminal (405) is electrically connected to the diaphragm (402), and the second electrical connection terminal (406) is electrically connected to the conductive layer (4042).

6. The MEMS chip as described in claim 1, characterized in that, The diameter of the vent (301) ranges from 2μm to 5μm, and the spacing between the vents (301) ranges from 2μm to 5μm.

7. The MEMS chip as described in claim 6, characterized in that, The acoustic impedance of the waterproof layer (30) is less than or equal to 600 Rayles.

8. The MEMS chip as described in claim 1, characterized in that, The waterproof layer (30) is one of silicon, polycrystalline silicon, and silicon nitride, and the thickness of the waterproof layer (30) ranges from 2μm to 20μm.

9. A MEMS microphone, characterized in that, Includes a MEMS chip (1) as described in any one of claims 1 to 8 and an ASIC chip (2), wherein the ASIC chip (2) is disposed on a PCB board (3), and the MEMS chip (1) and the ASIC chip (2) are connected by electrical connection lines (5).

10. The MEMS microphone as described in claim 9, characterized in that, It also includes a metal casing (4) disposed on the PCB board (3) to accommodate the MEMS chip (1) and the ASIC chip (2).

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