CN215420760U

CN215420760U - MEMS microphone structure and terminal

Info

Publication number: CN215420760U
Application number: CN202122018942.0U
Authority: CN
Inventors: 荣根兰; 孙恺; 孟燕子; 胡维
Original assignee: Memsensing Microsystems Suzhou China Co Ltd
Current assignee: Memsensing Microsystems Suzhou China Co Ltd
Priority date: 2021-08-25
Filing date: 2021-08-25
Publication date: 2022-01-04
Anticipated expiration: 2031-08-25

Abstract

Disclosed is a MEMS microphone structure comprising: a substrate having a through hole penetrating the substrate; the packaging shell is arranged on the first surface of the substrate and forms a cavity with the substrate in an enclosing mode; the MEMS chip and the ASIC chip are arranged on the first surface of the substrate in the cavity, the MEMS chip comprises a back cavity, and the back cavity of the MEMS chip is positioned above the through hole and is communicated with the through hole; and the sealing layer is positioned on the second surface of the substrate and covers the through hole, wherein the diameter of the through hole on the first surface of the substrate is smaller than or equal to that of the back cavity. The MEMS microphone structure provided by the application has the advantages that the through hole penetrating through the substrate corresponding to the back cavity position of the MEMS device is formed, so that the back cavity volume of the MEMS chip is increased, and the signal-to-noise ratio of the MEMS microphone structure is improved.

Description

MEMS microphone structure and terminal

Technical Field

The utility model relates to the technical field of micro electro mechanical systems, in particular to an MEMS microphone structure and a terminal.

Background

In the conventional microphone structure, in order to improve the performance of a microphone front sound product, two schemes of grooving a fixed depth on a PCB (printed circuit board) or digging a cavity in the PCB are generally adopted. But the increase volume of the fixed-depth grooves on the PCB is limited, so that the signal-to-noise ratio (SNR) is improved only a little; and the cavity is dug in the PCB, although the volume of the cavity can be greatly increased, the process is complex and the cost is high.

SUMMERY OF THE UTILITY MODEL

In view of the above problems, an object of the present invention is to provide a MEMS microphone structure and a terminal, which increase the back cavity volume of a MEMS device by forming a large through hole penetrating through a substrate corresponding to the back cavity position of the MEMS device, thereby improving the performance of the MEMS microphone structure.

According to an aspect of the present invention, there is provided a MEMS microphone structure, comprising: a substrate having a through hole penetrating the substrate; the packaging shell is arranged on the first surface of the substrate and forms a cavity with the substrate in an enclosing mode; the MEMS chip and the ASIC chip are arranged on the first surface of the substrate in the cavity, the MEMS chip comprises a back cavity, and the back cavity of the MEMS chip is positioned above the through hole and is communicated with the through hole; a sealing layer on the substrate second surface and covering the through hole, wherein a diameter of the through hole at the substrate first surface is equal to a diameter of the back cavity.

Optionally, the through hole includes a first through hole, and a diameter of the first through hole is equal to a diameter of the back cavity.

Optionally, the through hole includes a first through hole, and a diameter of the first through hole gradually increases from the first surface to the second surface of the substrate.

Optionally, the through holes include a first through hole and a second through hole, the second through hole extends from the second surface of the substrate to the inside of the substrate, and the diameter of the second through hole is larger than that of the first through hole.

Optionally, a ratio of the heights of the first through hole and the second through hole is 1/10-10.

Optionally, the method further comprises: and the sound hole is positioned on the packaging shell and is communicated with the cavity and the external environment.

Optionally, the sealing layer comprises a PTFE film or SU8 dry film sealing material.

According to another aspect of the present invention, there is provided a terminal comprising a MEMS microphone structure as described above.

According to the MEMS microphone structure provided by the utility model, the first through hole penetrating through the substrate corresponding to the back cavity position of the MEMS chip is formed, and the diameter of the first through hole is smaller than or equal to that of the back cavity of the MEMS chip, so that the back cavity volume of the MEMS chip is increased, and the performance of the MEMS microphone structure is improved. In another embodiment, the diameter of the first through hole gradually increases from the first surface to the second surface of the substrate, so that the volume of the back cavity can be further increased.

Furthermore, the diameter of a part of the first through hole is enlarged on the second surface of the substrate, so that the diameter of the enlarged second through hole is larger than that of the first through hole, and the back cavity of the MEMS chip is communicated with the first through hole and the second through hole, thereby enlarging the volume of the back cavity of the MEMS chip and further improving the performance of the MEMS microphone structure.

Further, the sealing layer is formed on the second surface of the substrate, and the first through hole or the second through hole is sealed by the sealing layer, so that the volume of the back cavity of the MEMS chip can be increased to a great extent, and the volume of the MEMS microphone structure cannot be increased.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

fig. 1 shows a schematic diagram of a MEMS microphone structure according to the prior art;

fig. 2 shows a schematic diagram of a MEMS microphone structure according to a first embodiment of the utility model;

fig. 3 shows a schematic diagram of a MEMS microphone structure according to a second embodiment of the utility model.

Detailed Description

The utility model will be described in more detail below with reference to the accompanying drawings. Like elements in the various figures are denoted by like reference numerals. For purposes of clarity, the various features in the drawings are not necessarily drawn to scale. In addition, certain well known components may not be shown. For simplicity, the semiconductor structure obtained after several steps can be described in one figure.

It will be understood that when a layer or region is referred to as being "on" or "over" another layer or region in describing the structure of the device, it can be directly on the other layer or region or intervening layers or regions may also be present. And, if the device is turned over, that layer, region, or regions would be "under" or "beneath" another layer, region, or regions.

If for the purpose of describing the situation directly above another layer, another area, the expression "directly above … …" or "above and adjacent to … …" will be used herein.

Fig. 1 shows a schematic diagram of a MEMS microphone structure according to the prior art. Referring to fig. 1, a prior art MEMS microphone structure 100 includes a substrate 101; a package housing 102 fixedly connected to the first surface of the substrate 101 and forming a cavity 104 with the substrate 101; a sound hole 103 located on the package housing 102, and the cavity 104 is communicated with the outside through the sound hole 103; an ASIC chip 107 fixed on the first surface of the substrate 101 within the cavity 104; the MEMS chip 106 is fixed on the first surface of the substrate 101 in the cavity 104 and electrically connected with the ASIC chip 107, a back cavity 105 is formed between the MEMS chip 106 and the substrate 101, and a groove 108 is formed in the first surface of the substrate 101 corresponding to the back cavity 105, wherein the groove 108 is used for increasing the volume of the back cavity 105, so that the performance of the device is improved. However, the formation of the groove 108 in the substrate 101 requires etching of the substrate, and it is difficult to control the depth during etching, and the groove formed in the substrate 101 is not so large in volume, and does not significantly improve the device performance.

The following detailed description of embodiments of the present invention is provided in connection with the accompanying drawings and examples.

Fig. 2 shows a schematic diagram of a MEMS microphone structure according to a first embodiment of the utility model.

Referring to fig. 2, a MEMS microphone structure 200 of a first embodiment of the present application includes: a substrate 201, wherein a first through hole 208 penetrating through the substrate 201 is formed in the substrate 201; the package housing 202, the package housing 202 is fixed on the first surface of the substrate 201, a cavity 204 is enclosed between the package housing 202 and the substrate 201, a sound hole 203 is formed on the package housing 202, the sound hole 203 communicates with the external environment and the cavity 204, and the first through hole 208 is located in the substrate 201 in the cavity 204; an ASIC chip 207 disposed on the first surface of the substrate 201 within the cavity 204; and the MEMS chip 206 is arranged on the first surface of the substrate 201 in the cavity 204, the MEMS chip 206 comprises a diaphragm and a back plate, and a back cavity 205 is formed between the MEMS chip 206 and the substrate 201. The MEMS chip 206 is located above the first through hole 208 in the substrate 201, and the back cavity 205 of the MEMS chip 206 corresponds to the first through hole 208 in the substrate 201, so that the back cavity 205 is communicated with the first through hole 208, and the volume of the back cavity 205 is increased.

Further, on the second surface of the substrate 201, a sealing layer 209 is also formed, the sealing layer 209 being for sealing an opening of the first through hole 208 at the second surface of the substrate 201, so that the first through hole 208 is in communication with only the back cavity 205 for increasing the volume of the back cavity 205 without communicating with the outside. The sealing layer 209 is made of a sealing material such as a PTFE film or a SU8 dry film, and has a thickness of the order of micrometers.

Specifically, the MEMS chip 206 serves as an inductive element for the sound signal, and the positions of the diaphragm and the back plate may be interchanged. The bottom of the MEMS chip 206 is fixedly connected to the first surface of the substrate 201 through a glue. The MEMS chip 206 further comprises a support structure for supporting the back plate and the diaphragm such that a back cavity 205 is formed between the back plate or the diaphragm and the first surface of the substrate 201. The back plate of the MEMS chip 206 and the diaphragm are disposed opposite to each other to form an inductive capacitor. When the pressure in the back cavity 205 changes, the diaphragm deforms, so that the capacitance changes, and an induction signal is output. The MEMS chip 206 is disposed over the first via 208 such that the back cavity 205 of the MEMS chip 206 communicates with the via 208. Further, the diameter of the first through hole 208 on the first surface of the substrate 201 is smaller than or equal to the diameter of the back cavity 205 of the MEMS chip 206, so that the volume of the back cavity 205 can be increased to a greater extent.

The ASIC chip 207 is an application specific integrated circuit chip, and is connected to the MEMS chip 206 by a wire. The asic chip is used to obtain the sensing signal output by the MEMS chip 206 and process the sensing signal.

The substrate 201 may be made of a commonly used substrate material such as RF-4, BT or ceramic substrate. A sealing ring surrounding along the edge of the first surface of the substrate 201 is further formed on the first surface of the substrate 201, and the package housing 202 is fixedly connected with the first surface of the substrate 201 through the sealing ring to form a cavity 204. Pads are formed on the second surface of the substrate 201 for providing electrical connection points. The substrate 201 may be a single-layer or multi-layer circuit board, and the first surface of the substrate 201 may also be formed with circuit structures, or electrical contacts, such as pads, etc. The substrate 201 may further have an electrical connection structure formed therein for connecting electrical contacts of the first surface and the second surface of the substrate 201.

The package housing 202 serves as a package housing of the vibration sensor package structure for protecting the internal electronic components, and a cavity 204 is formed between the package housing and the substrate 201. The packaging shell 202 can be made of metal, is high-temperature resistant, is simple in production process, and can be produced in large scale, and the metal shell packaging shell 202 also has the characteristics of corrosion resistance, electromagnetic shielding effect, high mechanical performance and the like, so that a product is protected well. In other embodiments, the package housing 202 may also be made of other hard materials such as plastic, which is not limited herein. The edge of the package housing 202 is fixed to the sealing ring on the first surface of the substrate 201 by welding or gluing, so that a cavity 204 is formed between the package housing 202 and the substrate 201.

In this embodiment, the back cavity 205 of the MEMS chip 206 is located above the first through hole 208 of the substrate 201, and the diameter of the first through hole 208 is smaller than or equal to the diameter of the back cavity 205, so that the volume of the back cavity 205 can be increased more, thereby improving the signal-to-noise ratio (SNR) of the MEMS microphone structure. Furthermore, with this process, the complexity of the process is not increased, and adding only a thin sealing layer 209 does not add much cost.

In this embodiment, the first through hole 208 is, for example, cylindrical in shape.

In other embodiments, the diameter of the first through hole 208 varies, for example, and gradually increases from the first surface to the second surface of the substrate 201, i.e., the cross-sectional shape perpendicular to the substrate surface is a trapezoid, so that the volume of the back cavity 205 can be further increased compared to the MEMS microphone structure shown in fig. 2.

Fig. 3 shows a schematic diagram of a MEMS microphone structure according to a second embodiment of the utility model. Compared with the MEMS microphone structure of the first embodiment, in the MEMS microphone structure of the second embodiment, the through hole penetrating through the substrate is divided into at least two parts, so that the volume of the back cavity can be further increased.

Referring to fig. 3, in the MEMS microphone structure 300, the through holes penetrating the substrate 201 include a first through hole 208 and a second through hole 210. The position of the first through hole 208 corresponds to the position of the back cavity of the MEMS chip 206, the diameter of the first through hole 208 is smaller than or equal to the diameter of the back cavity 205, and the first through hole 208 extends from the first surface of the substrate 201 to the inside of the substrate 201. The diameter of the second through hole 210 is larger than the diameter of the first through hole 208, the second through hole 210 extends toward the inside of the substrate 201 via the second surface of the substrate 201, and the second through hole 210 communicates with the back cavity 205 via the first through hole 208. Since the diameter of the second through hole 210 is larger than that of the first through hole 208, the volume of the back cavity 205 in the second embodiment is further increased compared to that in the first embodiment, so that the signal-to-noise ratio of the device can be further improved.

In this embodiment, referring to FIG. 3, the ratio of the height of the first via 208 extending into the substrate 201 to the height of the second via 210 extending into the substrate 201 is 1/10-10. The smaller the proportion of the height of the first through hole 208 to the thickness of the substrate 201 is, the larger the proportion of the height of the second through hole 210 to the rear of the substrate 201 is, so that the larger the back cavity volume added by the through hole is, the higher the signal-to-noise ratio of the device is.

Further, the second via hole 210 may be formed by opening a hole at all positions of the second surface of the substrate 201 except for the pad, and the like, and a sealing layer 209 is formed on the second surface of the substrate 201 for blocking a passage of the second via hole 210 communicating with the outside.

The second embodiment of the application realizes the further increase of the back cavity volume through the difference of the upper and lower through hole apertures, and the SNR of the product is improved. The scheme has the advantages of simple process, low cost and good performance, and is suitable for mass production.

In other embodiments, the shape, size, etc. of the through hole on the second surface of the substrate 201 may be changed, and may be a regular shape or an irregular shape.

According to the MEMS microphone structure provided by the utility model, the first through hole penetrating through the substrate corresponding to the back cavity position of the MEMS chip is formed, and the diameter of the first through hole is smaller than or equal to that of the back cavity of the MEMS chip, so that the back cavity volume of the MEMS chip is increased, and the performance of the MEMS microphone structure is improved.

In accordance with the embodiments of the present invention as set forth above, these embodiments are not exhaustive and do not limit the utility model to the precise embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the utility model and the practical application, to thereby enable others skilled in the art to best utilize the utility model and various embodiments with various modifications as are suited to the particular use contemplated. The utility model is limited only by the claims and their full scope and equivalents.

Claims

1. A MEMS microphone structure, comprising:

a substrate having a through hole penetrating the substrate;

the packaging shell is arranged on the first surface of the substrate and forms a cavity with the substrate in an enclosing mode;

the MEMS chip and the ASIC chip are arranged on the first surface of the substrate in the cavity, the MEMS chip comprises a back cavity, and the back cavity of the MEMS chip is positioned above the through hole and is communicated with the through hole;

a sealing layer on the substrate second surface and covering the through-hole,

wherein the diameter of the through hole on the first surface of the substrate is smaller than or equal to the diameter of the back cavity.

2. The MEMS microphone structure of claim 1 wherein the via comprises a first via having a diameter that is equal in size to a diameter of the back cavity.

3. The MEMS microphone structure of claim 1, wherein the via comprises a first via having a diameter that increases in size from the first surface to the second surface of the substrate.

4. The MEMS microphone structure of claim 1, wherein the via comprises a first via and a second via, the second via extending from the second surface of the substrate into the substrate, the second via having a diameter that is larger than a diameter of the first via.

5. The MEMS microphone structure of claim 4, wherein a ratio of the heights of the first via and the second via is 1/10-10.

6. The MEMS microphone structure of claim 1, further comprising: and the sound hole is positioned on the packaging shell and is communicated with the cavity and the external environment.

7. The MEMS microphone structure of claim 1, wherein the sealing layer comprises a PTFE film or SU8 dry film sealing material.

8. A terminal, characterized in that it comprises a MEMS microphone structure according to any of claims 1-7.