MEMS chip

Abstract

The utility model relates to an MEMS chip. The MEMS chip comprises a substrate; the sensor comprises a back plate and a first vibrating diaphragm and a second vibrating diaphragm which are respectively positioned on two sides of the back plate, and the first vibrating diaphragm and the second vibrating diaphragm are connected through a plurality of connecting columns; the connecting structure is connected with the substrate and the sensor, so that the back plate and the substrate are relatively fixed, the first vibrating diaphragm and the second vibrating diaphragm can vibrate relative to the substrate, the connecting structure comprises a first connecting plate parallel to the back plate, the first connecting plate annularly surrounds the first vibrating diaphragm and is connected with the first vibrating diaphragm, an isolation groove is formed in the first connecting plate and surrounds the first vibrating diaphragm, and the isolation groove is communicated with the first vibrating diaphragm. The isolation groove is filled with an insulating material to form an isolation ring, the isolation ring enables the first diaphragm and the part of the first connecting plate located outside the isolation groove to form insulation, the substrate is located on one side of the first connecting plate away from the second diaphragm, and the part of the first connecting plate located outside the isolation groove is connected with the substrate. According to the invention, the parasitic capacitance generated between the first diaphragm and the substrate can be reduced, the sensitivity of the sensor is improved, and the sensitivity of the MEMS chip is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of microphones, and particularly relates to a MEMS chip. Background Art

[0002] A MEMS microphone consists of three parts: a MEMS Sensor (MEMS chip), an ASIC chip, and a package. The performance of a MEMS microphone is mainly determined by the MEMS chip. Generally, the MEMS chip mainly includes a diaphragm, a backplate, and a substrate. There are through holes on the backplate. The diaphragm and the backplate form a parallel plate capacitor. A bias voltage is applied to the diaphragm or the backplate. The sound pressure acts on the diaphragm, causing the distance between the diaphragm and the backplate to change, thereby resulting in a change in capacitance and generating an output of a voltage signal.

[0003] For a traditional MEMS chip with a single-layer diaphragm structure, since there is an air gap between the diaphragm and the backplate, the air gap between the diaphragm and the backplate will generate squeeze film damping, resulting in a relatively large background noise of the microphone. To solve this problem, the patent with the publication number CN118158603A discloses a MEMS chip with a double-layer diaphragm structure. By respectively arranging a layer of diaphragm on both sides of the backplate, the edges of the two layers of diaphragms are hermetically connected to form a low-pressure sealed cavity between the two layers of diaphragms, thereby reducing the air squeeze film damping between the diaphragm and the backplate and reducing the background noise. At the same time, the two layers of diaphragms are mechanically coupled through connecting columns to make the two layers of diaphragms vibrate synchronously to achieve the output of differential signals and cancel out the interference of noise signals.

[0004] For the above-mentioned MEMS chip with a double-layer diaphragm structure, the connecting plate close to the substrate and the substrate are directly connected through a filling layer, resulting in a relatively large parasitic capacitance between the connecting plate and the substrate, and thus a relatively large parasitic capacitance between the diaphragm connected to the connecting plate and the substrate, affecting the sensitivity of the MEMS chip. Summary of the Utility Model

[0005] Based on the above description, the utility model provides a MEMS chip to solve the problem in the related technology that there is a relatively large parasitic capacitance between the diaphragm and the substrate, affecting the sensitivity of the MEMS chip.

[0006] The technical solution of the utility model to solve the above technical problems is as follows:

[0007] The present application provides a MEMS chip, and the technical solution adopted is as follows:

[0008] A MEMS chip, comprising:

[0009] A substrate;

[0010] A sensor, which includes a backplane, a first diaphragm and a second diaphragm respectively located on both sides of the backplane. The first diaphragm and the second diaphragm are respectively arranged at intervals with the backplane. The edges of the first diaphragm and the second diaphragm are hermetically connected. A low-pressure sealed cavity is formed between the first diaphragm and the second diaphragm. The backplane is located in the low-pressure sealed cavity. The first diaphragm and the second diaphragm are connected by a plurality of connecting columns. The connecting columns pass through the backplane, and the plurality of connecting columns are spaced apart in the plane of the backplane. Through holes for the connecting columns to pass through are provided on the backplane.

[0011] A connecting structure, which connects the substrate and the sensor, makes the backplane relatively fixed with the substrate, and enables the first diaphragm and the second diaphragm to vibrate relative to the substrate. The connecting structure includes a first connecting plate parallel to the backplane. The first connecting plate is annularly arranged around the first diaphragm and is connected to the first diaphragm. An isolation groove is formed around the first diaphragm on the first connecting plate. An insulating material is filled in the isolation groove to form an isolation ring. The isolation ring insulates the part of the first diaphragm and the first connecting plate located outside the isolation groove. The substrate is located on the side of the first connecting plate away from the second diaphragm, and the part of the first connecting plate located outside the isolation groove is connected to the substrate.

[0012] Preferably, the first connecting plate is arranged at intervals with the substrate in a direction perpendicular to its plane, and the part of the first connecting plate located outside the isolation groove and the substrate are filled with a filling layer.

[0013] Preferably, a blocking ring is provided between the first connecting plate and the substrate. The blocking ring is arranged around the isolation groove and connects the first connecting plate and the substrate. The filling layer between the first connecting plate and the substrate is filled outside the blocking ring.

[0014] Preferably, a first insulating layer is provided on the side of the first connecting plate away from the substrate. The first insulating layer fills into the isolation groove to form the isolation ring. A limiting groove is formed around the isolation groove on the first connecting plate. The first insulating layer fills into the limiting groove and extends to be connected with the substrate to form the blocking ring.

[0015] Preferably, the connecting structure further includes a second connecting plate and a third connecting plate parallel to the first connecting plate. The second connecting plate is annularly arranged around the backplane and is connected to the backplane. The third connecting plate is annularly arranged around the second diaphragm and is connected to the second diaphragm. The space between the first connecting plate and the second connecting plate and the space between the second connecting plate and the third connecting plate are filled with a filling layer.

[0016] Preferably, a second insulating layer is provided on the side of the third connecting plate close to the second connecting plate.

[0017] Preferably, the connecting column includes a connecting block and a hollow connecting pipe. One end of the connecting pipe is connected to the first diaphragm, and the other end passes through the back plate and is connected to the second diaphragm through the connecting block.

[0018] Preferably, the connecting column further includes a core body filled in the connecting pipe, and the dielectric constant of the material of the core body is less than the dielectric constant of the material of the connecting pipe.

[0019] Compared with the prior art, the technical solution of the present application has the following beneficial technical effects:

[0020] 1. The present application forms a differential capacitive sensor through the first diaphragm, the second diaphragm and the back plate. When the sensor is connected to the substrate through the connecting structure, the back plate is relatively fixed to the substrate, and the first diaphragm and the second diaphragm can vibrate relative to the substrate, so that differential signal output can be realized through the vibration of the first diaphragm and the second diaphragm. In the connecting structure, the first diaphragm is connected to the substrate through the first connecting plate. An isolation groove is formed on the first connecting plate, and an insulating material is filled in the isolation groove to form an isolation ring, so that the parts of the first diaphragm and the first connecting plate located outside the isolation groove are insulated. The part of the first connecting plate located outside the isolation groove is connected to the substrate, so that insulation is formed between the first diaphragm and the substrate, thereby reducing the parasitic capacitance generated between the first diaphragm and the substrate and improving the sensitivity of the sensor, that is, improving the sensitivity of the MEMS chip.

[0021] 2. The connecting column of the present application is provided to include a core body, a connecting pipe and a connecting block. On the one hand, the cross-sectional area of the connecting column can be increased to improve the structural strength of the connecting column, reduce the stress at the connection between the diaphragm and the connection, and improve the stability of the sensor. And the dielectric constant of the material of the core body is less than the dielectric constant of the material of the connecting pipe. Compared with the connecting column completely made of the material of the connecting pipe, the parasitic capacitance between the first diaphragm and the second diaphragm can be reduced, thereby further improving the sensitivity of the sensor, that is, the MEMS chip. Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of the MEMS chip provided in the embodiment of the present invention;

[0023] Figure 2 It is a schematic structural diagram of the connecting column in the MEMS chip provided in the embodiment of the present invention;

[0024] Figure 3 This Figure 1 Partial enlarged schematic diagram.

[0025] In the drawings, the list of components represented by each reference numeral is as follows:

[0026] 1. Substrate; 2. Sensor; 21. Backplane; 22. First diaphragm; 23. Second diaphragm; 24. Connecting column; 241. Connecting pipe; 242. Connecting block; 243. Core; 3. Connecting structure; 31. First connecting plate; 311. Isolation groove; 32. Second connecting plate; 33. Third connecting plate; 34. Filling layer; 35. Sealing film; 36. First insulating layer; 37. Second insulating layer; 38. Isolation ring; 39. Barrier ring. Detailed implementation manners

[0027] To facilitate the understanding of the present application, the present application will be described more comprehensively below with reference to the relevant accompanying drawings. Embodiments of the present application are shown in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used in the description of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0029] It can be understood that spatial relationship terms such as "under", "below", "beneath", "underneath", "above", "over" etc. can be used herein to describe the relationship of one element or feature shown in the drawings with other elements or features. It should be understood that in addition to the orientation shown in the drawings, spatial relationship terms also include different orientations of the devices during use and operation. For example, if the device in the drawing is flipped, the element or feature described as "under other elements" or "beneath it" or "under it" will be oriented "above" the other elements or features. Therefore, the exemplary terms "under" and "beneath" can include both the upper and lower orientations. In addition, the device can also have other orientations (such as rotating 90 degrees or other orientations), and the spatial description language used herein is accordingly interpreted.

[0030] It should be noted that when an element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediate element. In the following embodiments, "connection", if there is an electrical signal or data transfer between the connected circuits, modules, units, etc., should be understood as "electrical connection", "communication connection", etc.

[0031] As used herein, the singular forms "a", "an" and "the" may also include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising", "including" or "having", etc., specify the presence of the stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.

[0032] Referring Figures 1-3 As shown, this embodiment provides a MEMS chip, which includes a substrate 15, a sensor 2, and a connection structure 3 connecting the substrate 1 and the sensor 2. When the sensor 2 is connected to the substrate 1 through the connection structure 3, the backplane 21 is relatively fixed to the substrate 1, and the first diaphragm 22 and the second diaphragm 23 can vibrate relative to the substrate 1.

[0033] Referring Figure 1 and Figure 3 As shown, the sensor 2 includes a backplane 21, a first diaphragm 22, a second diaphragm 23, and a plurality of connection posts 24. The first diaphragm 22 and the second diaphragm 23 are respectively located on both sides of the backplane 21. The first diaphragm 22 and the second diaphragm 23 are respectively arranged at intervals with the backplane 21. The edges of the first diaphragm 22 and the second diaphragm 23 are hermetically connected, and a low-pressure sealed cavity is formed between the first diaphragm 22 and the second diaphragm 23. The backplane 21 is located in the low-pressure sealed cavity. The connection posts 24 pass through the backplane 21 and connect the first diaphragm 22 and the second diaphragm 23. The plurality of connection posts 24 are spaced apart in the plane of the backplane 21, and through holes for the connection posts 24 to pass through are provided on the backplane 21.

[0034] Referring Figures 1-2 As shown, the connection post 24 includes a connection block 242 and a hollow connection tube 241. One end of the connection tube 241 is connected to the first diaphragm 22, and the other end passes through the backplane 21 and is connected to the second diaphragm 23 through the connection block 242.

[0035] Referring Figure 2 As shown, the connection post 24 may further include a core 243 filled in the connection tube 241. The core 243 fills the inner cavity of the connection tube 241 to form a solid connection post 24 structure, which can further improve the structural strength of the connection post 24. Whether to include the core 243 is selected according to needs in actual design. In this embodiment, the connection post 24 including the core 243 is used for illustration.

[0036] The dielectric constant of the material of the core 243 is less than the dielectric constant of the material of the connection tube 241. Compared with the connection post 24 formed entirely of the material of the connection tube 241, the parasitic capacitance between the two diaphragms can be reduced.

[0037] The connecting pipe 241 and the connecting block 242 are integrally formed, making the connecting column 24 have a relatively high structural strength. The projection of the connecting block 242 on the second diaphragm 23 covers the projection of the connecting pipe 241 on the second diaphragm 23. The connecting area between the connecting block 242 and the second diaphragm 23 is larger, and the force-bearing area of the diaphragm is larger, reducing the stress at the connection between the second diaphragm 23 and the connecting column 24.

[0038] Specifically, the cross-sectional shape of the connecting pipe 241 can be a circular ring, an elliptical ring or a polygonal ring. The cross-sectional shape of the corresponding core body 243 is the same as the inner circular shape of the cross-section of the connecting pipe 241, and the cross-sectional shape of the connecting block 242 is designed to be the same as the outer circular shape of the cross-section of the connecting pipe 241. This makes the strength of the connecting column 24 uniform and enables the peripheries of the connections between the first diaphragm 22 and the second diaphragm 23 and the connecting column 24 to be evenly stressed, avoiding stress concentration.

[0039] Refer to Figure 1 and Figure 3 As shown in the figure, the connecting structure 3 includes a first connecting plate 31, a second connecting plate 32 and a third connecting plate 33 that are parallel to the back plate 21. The first connecting plate 31 is annularly arranged around the first diaphragm 22 and is connected to the first diaphragm 22. The second connecting plate 32 is annularly arranged around the back plate 21 and is connected to the back plate 21. The third connecting plate 33 is annularly arranged around the second diaphragm 23 and is connected to the second diaphragm 23. The space between the first connecting plate 31 and the second connecting plate 32 and the space between the second connecting plate 32 and the third connecting plate 33 are filled with a filling layer 34 to form a spaced arrangement.

[0040] Specifically, the first diaphragm 22 is connected to the first connecting plate 31 through a plurality of first pins around its periphery. The back plate 21 is connected to the second connecting plate 32 through a plurality of second pins around its periphery. The second diaphragm 23 is connected to the third connecting plate 33 through a plurality of third pins around its periphery. The number of the first pins, the second pins and the third pins is the same. The projections of the first pins and the third pins on the back plate 21 coincide one by one, and a second pin is arranged between the first pin and the second pin whose projections on the back plate 21 coincide. This setting can reduce the stiffness of the diaphragm, make the diaphragm have a larger effective area, and thus have higher sensitivity.

[0041] Refer to Figure 1 and Figure 3As shown, the edges of the first diaphragm 22 and the second diaphragm 23 are connected by a sealing film 35 to form a seal. The sealing film 35 also connects the first pin and the second pin that overlap in projection on the back plate 21, and the sealing film 35 extends to the connecting structure 3 and connects the inner edges of the first connecting plate 31 and the third connecting plate 33, so as to form a sealed cavity between the first diaphragm 22 and the second diaphragm 23. When manufacturing the chip, it is manufactured in a low-pressure environment, so that a low-pressure sealed cavity can be formed between the first diaphragm 22 and the second diaphragm 23. The back plate 21 is completely located in the low-pressure sealed cavity between the first diaphragm 22 and the second diaphragm 23 and is not connected to the first diaphragm 22, the second diaphragm 23 and the sealing film 35. The first diaphragm 22 and the second diaphragm 23 can vibrate freely relative to the back plate 21. In the attached drawings of this embodiment, among the connecting columns 24 near the edge of the diaphragm, the outside of the connecting pipe 241 and the sealing film 35 are formed as a whole.

[0042] Referring to Figure 1 and Figure 3 As shown, a first insulating layer 36 is provided on the side of the first connecting plate 31 close to the second connecting plate 32, and a second insulating layer 37 is provided on the side of the third connecting plate 33 close to the second connecting plate 32. The setting of the first insulating layer 36 and the second insulating layer 37 makes the first connecting plate 31, the second connecting plate 32 and the third connecting plate 33 insulated from each other, that is, the first diaphragm 22, the second diaphragm 23 and the back plate 21 are insulated from each other, thereby improving the sensitivity of the sensor 2. The outside of the second insulating layer 37 extends towards the first connecting plate 31 to cover the filling layer 34, the outside edge of the first insulating layer 36 and the first connecting plate 31, and in cooperation with the structure of the sealing film 35, further improves the insulation effect and the sensitivity of the sensor 2.

[0043] Referring to Figure 1 and Figure 3 As shown, the base 1 is located on the side of the first connecting plate 31 away from the second diaphragm 23. The base 1 surrounds the first diaphragm 22 of the sensor 2 and is connected to the first connecting plate 31. An isolation groove 311 is formed on the first connecting plate 31 around the first diaphragm 22, and the isolation groove 311 is filled with an insulating material to form an isolation ring 38. The isolation ring 38 insulates the part of the first diaphragm 22 and the first connecting plate 31 located outside the isolation groove 311, and the part of the first connecting plate 31 located outside the isolation groove 311 is connected to the base 1.

[0044] Referring to Figure 1 and Figure 3 As shown, the setting of the isolation groove 311 and the isolation ring 38 in the isolation groove 311 on the first connecting plate 31 makes the part of the first connecting plate 31 located inside the isolation groove 311 insulated from the base 1, that is, the first diaphragm 22 and the base 1 are insulated from each other, reducing the parasitic capacitance between the first diaphragm 22 and the base 1, thereby improving the sensitivity of the chip.

[0045] Reference Figure 1 and Figure 3 As shown, specifically, the first connecting plate 31 is spaced from the base 1 in a direction perpendicular to its plane, and the portion of the first connecting plate 31 outside the isolation groove 311 is filled with a filling layer 34 between the first connecting plate 31 and the base 1 to achieve the connection between the first connecting plate 31 and the base 1. The filling layer 34 between the first connecting plate 31 and the base 1 serves to connect the base 1 and the first connecting plate 31 and keeps a gap between the first connecting plate 31 and the base 1, that is, keeps a gap between the first diaphragm 22 and the base 1.

[0046] Reference Figure 1 and Figure 3 As shown, a blocking ring 39 is provided between the first connecting plate 31 and the base 1. The blocking ring 39 surrounds the isolation groove 311 and connects the first connecting plate 31 and the base 1. The filling layer 34 between the first connecting plate 31 and the base 1 is filled outside the blocking ring 39. The blocking ring 39 serves as an etching boundary when the filling layer 34 between the first connecting plate 31 and the base 1 is etched and formed.

[0047] Reference Figure 1 and Figure 3 As shown, in this embodiment, the isolation ring 38 is formed by filling the first insulating layer 36 into the isolation groove 311. And, a limiting groove is formed around the isolation groove 311 on the first connecting plate 31. The blocking ring 39 is formed by filling the first insulating layer 36 into the limiting groove and extending to connect with the base 1. The outside of the second insulating layer 37 extends to connect with the base 1.

[0048] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A MEMS chip, characterized in that: include: Base (1); A sensor (2), comprising a back plate (21) and a first diaphragm (22) and a second diaphragm (23) respectively located on both sides of the back plate (21), wherein the first diaphragm (22) and the second diaphragm (23) are respectively spaced apart from the back plate (21), the edges of the first diaphragm (22) and the second diaphragm (23) are sealed and connected, a low-pressure sealed cavity is formed between the first diaphragm (22) and the second diaphragm (23), the back plate (21) is located in the low-pressure sealed cavity, the first diaphragm (22) and the second diaphragm (23) are connected via a plurality of connecting posts (24), the connecting posts (24) pass through the back plate (21), the plurality of connecting posts (24) are spaced apart in the plane of the back plate (21), and a through hole for the connecting posts (24) to pass through is provided on the back plate (21); A connecting structure (3) is provided, which connects the substrate (1) and the sensor (2), so that the back plate (21) is relatively fixed to the substrate (1), and the first diaphragm (22) and the second diaphragm (23) can vibrate relative to the substrate (1), the connecting structure (3) comprises a first connecting plate (31) parallel to the back plate (21), the first connecting plate (31) is annularly surrounding the outside of the first diaphragm (22) and connected to the first diaphragm (22), the first connecting plate (31) surrounding the first diaphragm (22) The first diaphragm (22) is provided with an isolation groove (311), and the isolation groove (311) is filled with insulating material to form an isolation ring (38). The isolation ring (38) insulates the first diaphragm (22) and the portion of the first connecting plate (31) located outside the isolation groove (311). The base (1) is located on a side of the first connecting plate (31) away from the second diaphragm (23), and the portion of the first connecting plate (31) located outside the isolation groove (311) is connected to the base (1).

2. The MEMS chip according to claim 1, characterized in that: The first connecting plate (31) is spaced apart from the base (1) in a direction perpendicular to its plane, and a filling layer (34) is provided between a portion of the first connecting plate (31) located outside the isolation groove (311) and the base (1).

3. The MEMS chip according to claim 2, characterized in that: A blocking ring (39) is provided between the first connecting plate (31) and the base (1); the blocking ring (39) is arranged around the isolation groove (311) and connects the first connecting plate (31) and the base (1); and a filling layer (34) between the first connecting plate (31) and the base (1) is filled on the outside of the blocking ring (39).

4. The MEMS chip according to claim 3, characterized in that: A first insulating layer (36) is provided on a side of the first connecting plate (31) away from the base (1), the first insulating layer (36) is filled into the isolation groove (311) to form the isolation ring (38), a limiting groove is provided on the first connecting plate (31) around the isolation groove (311), the first insulating layer (36) is filled into the limiting groove and extends to connect with the base (1) to form the blocking ring (39).

5. The MEMS chip according to claim 1, characterized in that: The connection structure (3) also includes a second connection plate (32) and a third connection plate (33) parallel to the first connection plate (31); the second connection plate (32) is annularly surrounded outside the back plate (21) and connected to the back plate (21); the third connection plate (33) is annularly surrounded outside the second diaphragm (23) and connected to the second diaphragm (23); a filling layer (34) is used to fill between the first connection plate (31) and the second connection plate (32) and between the second connection plate (32) and the third connection plate (33).

6. The MEMS chip according to claim 5, characterized in that: A second insulating layer (37) is provided on one side of the third connecting plate (33) close to the second connecting plate (32).

7. The MEMS chip according to claim 1, characterized in that: The connecting column (24) comprises a connecting block (242) and a hollow connecting tube (241); one end of the connecting tube (241) is connected to the first diaphragm (22), and the other end passes through the back plate (21) and is connected to the second diaphragm (23) via the connecting block (242).

8. The MEMS chip according to claim 7, characterized in that: The connecting column (24) further comprises a core (243) filled in the connecting tube (241), and the dielectric constant of the material of the core (243) is smaller than the dielectric constant of the material of the connecting tube (241).

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