CN106996827B - A sensing diaphragm and MEMS microphone - Google Patents

Abstract

The invention discloses a sensing diaphragm and a MEMS microphone, comprising a sensitive part located in a central region, and a fixed part located at the outer edge of the sensitive part and integrally formed with the sensitive part; further comprising extending from the fixed part to the edge of the sensitive part A positional and non-closed slit portion, the slit portion encloses a holding portion on the sensing diaphragm with a root portion located on the fixed portion and a free end extending to the upper edge of the sensitive portion; the sensitive portion is configured to be impacted It is displaced relative to the holding part at the time, so as to form an air flow passage between the holding part and the sensitive part. Different from the traditional pressure relief valve structure, the sensing diaphragm of the present invention has less influence on the vibration characteristics of the sensitive part and better dynamic stability of the sensitive part.

Description

A sensing diaphragm and MEMS microphone

technical field

The present invention relates to a sensing diaphragm, in particular to a diaphragm suitable for sound production; the present invention also relates to a MEMS microphone.

Background technique

MEMS sensing components are now widely used in consumer electronic products. How to speed up the product production process is the focus of current component suppliers. For example, the dust generated during the production and assembly of mobile phones is directly cleaned by air guns. Lowest cost option. Therefore, it is necessary to propose an anti-blow improvement solution for loud pressure or atmospheric pressure for the MEMS sensor, so as to avoid the rupture of the microphone due to the cleaning of the air gun during the assembly process.

For example, in the field of microphones, the current improvement solution is to provide a pressure relief hole or a pressure relief valve structure on the diaphragm of the MEMS microphone. However, the structure of the pressure relief hole will reduce the effective area of the diaphragm; the pressure relief valve structure set on the diaphragm will directly affect the vibration characteristics of the diaphragm, especially the low frequency characteristics of the diaphragm, and the dynamic stability of the diaphragm is relatively poor .

SUMMARY OF THE INVENTION

An object of the present invention is to provide a new technology solution for sensing diaphragm.

According to a first aspect of the present invention, a sensing diaphragm is provided, comprising a sensitive portion located in a central region, and a fixed portion located at an outer edge of the sensitive portion and integrally formed with the sensitive portion; further comprising extending from the fixed portion to A non-closed slit portion at the edge of the sensitive portion, the slit portion encloses a holding portion on the sensing diaphragm with a root portion located on the fixed portion and a free end extending to the upper edge position of the sensitive portion; the sensitive portion is configured as When being impacted, it is displaced relative to the holding part, so as to form an air flow passage between the holding part and the sensitive part.

Optionally, at least one holding part is provided.

Optionally, there are at least three holding parts, which are evenly distributed in the circumferential direction of the edge of the sensitive part.

Optionally, the slot portion includes a first segment extending from the fixing portion to the sensitive portion, and a second segment extending from the end of the first segment to the fixing portion in a detour.

Optionally, the first segment and the second segment are symmetrical along their central axis.

Optionally, the entire slit portion is U-shaped, square, semi-circular or semi-elliptical.

Optionally, the free ends of the first segment and the second segment are provided with extension parts that deviate from their own extension directions.

Optionally, the ratio of the area of the slit portion extending on the sensitive portion to the area of the sensitive portion is 5%-50%.

Optionally, the slit portion is formed by etching or etching.

According to another aspect of the present invention, a MEMS microphone is also provided, comprising a back electrode and the above-mentioned sensing diaphragm.

The sensing diaphragm of the present invention is different from the traditional pressure relief valve structure. The pressure relief air flow passage is generated by the pressure deformation of the sensitive part itself, and the air flow passage can be adjusted in real time according to the internal and external pressure difference of the sensitive part. (Real-time adjustment of the pressure relief opening rate through its own pressure deformation), providing a pressure relief path to protect the sensing diaphragm. In the sensing diaphragm of the present invention, since the airflow channel is located at the edge of the sensitive part and formed by the displacement of the sensitive part itself, the airflow channel has less influence on the vibration characteristics of the sensitive part, and the dynamic stability of the sensitive part is improved. better.

The inventor of the present invention found that in the prior art, the pressure relief valve structure provided on the diaphragm directly affects the vibration characteristics of the diaphragm, especially the low frequency characteristics of the diaphragm, and the dynamic stability of the diaphragm is relatively poor. Therefore, the technical tasks to be achieved by the present invention or the technical problems to be solved are never thought or expected by those skilled in the art, so the present invention is a new technical solution.

Other features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings.

Description of drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

FIG. 1 is a schematic structural diagram of the MEMS microphone of the present invention.

FIG. 2 is a top view of the sensing diaphragm of the present invention.

FIG. 3 is a schematic structural diagram of the slit portion in FIG. 2 .

FIG. 4 is a schematic diagram of the displacement of the sensing diaphragm in FIG. 1 when it is impacted.

FIG. 5 is a schematic structural diagram of another embodiment of the slit portion of the present invention.

Detailed ways

Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the invention unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such techniques, methods, and apparatus should be considered part of the specification.

In all examples shown and discussed herein, any specific values should be construed as illustrative only and not limiting. Accordingly, other instances of the exemplary embodiment may have different values.

It should be noted that like numerals and letters refer to like items in the following figures, so once an item is defined in one figure, it does not require further discussion in subsequent figures.

The present invention provides a sensing diaphragm, which can be a diaphragm applied in a microphone structure, or a sensitive film applied in other sensor structures, such as a pressure sensor, a sensitive film layer in a gas sensor. The structures, materials, and application environments of these sensing diaphragms belong to the common knowledge in the field of sensors, and will not be described in detail here.

For ease of expression, a microphone is taken as an example to describe the technical solution of the present invention in detail. It should be understood that, for those skilled in the art, it can also be sensors of other structures.

1, a MEMS microphone provided by the present invention includes a substrate 1, and a capacitor structure formed on the substrate 1, the capacitor structure includes a sensing diaphragm (diaphragm) and a back electrode 6; the sensing The sensing diaphragm and the back electrode 6 are supported by a support portion 7 , so that there is a certain gap between the sensing diaphragm and the back electrode 6 . The capacitor structure can be a structure with the back electrode 6 on top and the sensing diaphragm on the bottom, as shown in FIG. 1 ; for those skilled in the art, it can also be a structure with the back electrode 6 on the bottom and the sensing diaphragm on the top. The structure is not described in detail here.

The sensing diaphragm of the present invention, referring to FIG. 2 , includes a sensitive part 2 located in the middle region, and a fixed part 5 located at the outer edge of the sensitive part 2 and integrally formed with the sensitive part 2; the sensitive part 2 serves as the vibration of the microphone The sound pickup of the microphone mainly depends on the vibration characteristics of the sensitive part 2 . The fixing part 5 is used to connect the entire sensing diaphragm on the substrate 1 , so that the sensing part 2 can be suspended above the back cavity of the substrate 1 . In the specific manufacturing process, a thin film layer is first deposited on the substrate 1 or on the insulating layer above the substrate 1, and then the fixed part 5 located on the outer side and the sensitive part located in the central region are formed by etching or etching process 2.

Of course, for those skilled in the art, in order to improve the vibration characteristics of the sensitive part 2, a folded ring part (not shown) is also provided between the sensitive part 2 and the fixed part 5, and through the folded ring part The sensitivity of the vibration of the sensitive part 2 can be significantly improved.

The sensing diaphragm of the present invention further includes a slit portion 4 extending from the fixing portion 5 to the edge of the sensitive portion 2 , the slit portion 4 is non-closed, and the non-closed slit portion 4 surrounds the sensing diaphragm. The holding part 3 is formed, the root of the holding part is located on the fixing part 5 , and the free end of the holding part extends to the edge of the sensitive part 2 , refer to FIGS. 1 and 2 . The holding portion 3 is a part of the sensing diaphragm, and the shape of the holding portion 3 is determined by the shape of the slit portion 4 . During molding, the slit portion 4 can be formed, for example, by etching or etching the silicon film layer.

Since the root of the holding part 3 is located at the position of the fixed part 5 of the sensing diaphragm, and the free end is located at the edge of the sensitive part 2, when the sensing diaphragm is connected to the substrate, when it is impacted by loud pressure or atmospheric air , the sensitive part 2 will be displaced upward or downward relative to the holding part 3 due to a large impact, thus forming an air flow channel between the holding part 3 and the sensitive part 2 that can relieve pressure.

In a specific embodiment of the present invention, referring to FIG. 3 , the slot portion 4 includes a first segment 40 extending from the fixing portion 5 to the sensitive portion 2 , and a first segment 40 detouringly extending from the first segment 40 to the fixing portion 5 . 2nd paragraph 41. That is to say, the open end of the slit part 4 is located at the position of the fixed part 5 , and the closed end surrounded by the first segment 40 and the second segment 41 is located on the sensitive part 2 , so that the first segment 40 and the second segment 41 are located on the sensitive part 2 . The root of the enclosed holding part 3 is located at the position of the fixed part 5 , and the free end of the holding part 3 is located at the position of the sensitive part 2 of the sensing diaphragm.

Referring to FIG. 4 , when the sensing diaphragm is subjected to a loud sound pressure from top to bottom, since the free end of the holding part 3 only extends to the edge position of the sensitive part 2, the pressure surface of the sensitive part 2 is much larger than that of the holding part 3, The sensitive part 2 will be displaced downward due to the greater impact, while the holding part 3 will remain stationary, which makes the sensitive part 2 and the holding part 3 staggered from each other, thus opening the holding part 3 and the sensitive part. The air flow channel between 2 so that the pressure can be released quickly.

The sensing diaphragm of the present invention is different from the traditional pressure relief valve structure. The pressure relief air flow passage is generated by the pressure deformation of the sensitive part itself, and the air flow passage can be adjusted in real time according to the internal and external pressure difference of the sensitive part. (Real-time adjustment of the pressure relief opening rate through its own pressure deformation), providing a pressure relief path to protect the sensing diaphragm. In the sensing diaphragm of the present invention, since the airflow passage is located at the edge of the sensitive part and is formed by the displacement of the sensitive part itself, the airflow passage has very little influence on the vibration characteristics of the sensitive part, and the dynamic stability of the sensitive part is very small. better.

The holding portion 3 of the present invention may be provided in one, two, three or more. It is preferred in the present invention that at least three holding parts 3 are provided, and the three holding parts 3 are evenly distributed in the circumferential direction of the edge of the sensitive part 2 . For example, when the sensitive part 2 has a circular structure, the three holding parts 3 are evenly distributed in the circumferential direction of the edge of the sensitive part 2 to ensure the uniformity of pressure relief and the stability of the displacement of the sensitive part 2 .

In a preferred embodiment of the present invention, the first segment 40 and the second segment 41 are symmetrical along the central axis thereof, so that the formed holding portion 3 is a centrally symmetric structure. Of course, for those skilled in the art, the holding part 3 can also be an asymmetric structure, and when the sensitive part 2 is displaced, a pressure-releasing air flow channel can also be formed.

The entire slit portion may be in a regular or irregular U-shape, square, semi-circle, semi-elliptical shape, refer to FIG. 5 , or other shapes known to those skilled in the art.

Preferably, the free ends of the first segment 40 and the second segment 41 are provided with extension portions 42 that deviate from their own extending directions. Referring to FIG. 3 , the two extending portions 42 may extend toward the center of the slit portion 4 , or may extend in opposite directions. The arrangement of the extension portion 42 can well relieve the stress when the slit portion 4 is formed on the film layer, so as to ensure the flatness and stability of the sensing film.

The extension length of the slit part 4 on the sensitive part 2 of the present invention represents the extended length of the holding part 3 on the sensitive part 2 , which determines the size of the airflow passage after the sensitive part 2 is displaced. That is to say, the greater the extension length of the slit portion 4 on the sensitive portion 2 is, the greater the pressure relief capability of the air flow passage between the sensitive portion 2 and the holding portion 3 is.

In addition, if the area of the sensitive part 2 occupied by the holding part 3 is too large, the holding part 3 will also be displaced relative to the sound pressure, which is contrary to the technical solution of the present application. Therefore, it is necessary to design the dimensional proportional relationship between the holding part 3 and the sensitive part 2 , which can be obtained by those skilled in the art through effective experiments. In a specific embodiment of the present invention, the proportional relationship between the area of the slit portion 4 extending on the sensitive portion 2 and the area of the sensitive portion 2 is preferably set at 5%-50%.

Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are provided for illustration only and not for the purpose of limiting the scope of the present invention. Those skilled in the art will appreciate that modifications may be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the invention is defined by the appended claims.

Claims (8)

1. A sensing diaphragm, characterized in that it comprises a sensitive part (2) located in a central region, and a fixed part (5) located at the outer edge of the sensitive part (2) and integrally formed with the sensitive part (2). , the sensitive part (2) and the fixed part (5) are formed on the same thin film layer by an etching or corrosion process; it also includes extending from the fixed part (5) to the edge position of the sensitive part (2) without being closed The slit portion (4) is formed on the sensing diaphragm to form a holding portion (3) whose root portion is located on the fixed portion (5) and whose free end extends to the upper edge of the sensitive portion (2). ; the sensitive part (2) is configured to be displaced relative to the holding part (3) when being impacted, so as to form an air flow passage between the holding part (3) and the sensitive part (2); The slot portion (4) includes a first segment (40) extending from the fixing portion (5) to the sensitive portion (2), and a second segment (40) detouringly extending from the end of the first segment (40) to the fixing portion (5). Second paragraph (41); The free ends of the first segment (40) and the second segment (41) are provided with extension parts (42) that deviate from their own extension directions. 2 . The sensing diaphragm according to claim 1 , wherein at least one holding part ( 3 ) is provided. 3 . 3 . The sensing diaphragm according to claim 2 , wherein at least three holding parts ( 3 ) are provided, which are evenly distributed in the circumferential direction of the edge of the sensitive part ( 2 ). 4 . 4. The sensing diaphragm according to claim 1, wherein the first segment (40) and the second segment (41) are symmetrical along the central axis thereof. 5 . The sensing diaphragm according to claim 1 , wherein the slit portion ( 4 ) is U-shaped, square, semi-circular or semi-elliptical as a whole. 6 . 6. The sensing diaphragm according to claim 1, wherein the ratio of the area of the slit (4) extending on the sensitive part (2) to the area of the sensitive part (2) is 5%-50% . 7. The sensing diaphragm according to claim 1, characterized in that: the slit portion (4) is formed by etching or etching. 8. A MEMS microphone comprising a back electrode and a sensing diaphragm according to any one of claims 1-7.

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