CN210579221U

CN210579221U - Silicon microphone

Info

Publication number: CN210579221U
Application number: CN201921532050.9U
Authority: CN
Inventors: 张永强; 唐行明; 梅嘉欣; 李刚
Original assignee: Memsensing Microsystems Suzhou China Co Ltd
Current assignee: Memsensing Microsystems Suzhou China Co Ltd
Priority date: 2019-09-16
Filing date: 2019-09-16
Publication date: 2020-05-19
Anticipated expiration: 2029-09-16

Abstract

The utility model provides a silicon microphone, which comprises a shell, wherein the shell is provided with a sound inlet hole; the base plate and the shell form an accommodating cavity, the sound inlet hole is communicated with the accommodating cavity, one surface of the base plate is provided with a concave cavity, and the concave cavity is provided with an opening; and the acoustic assembly is positioned in the accommodating cavity and arranged on the surface of the substrate, the acoustic assembly comprises a MEMS sensor, the MEMS sensor covers the opening, the concave cavity is used as an expanded rear chamber of the MEMS sensor, and the area between the sound inlet hole and the MEMS sensor is used as a front chamber of the MEMS sensor. The utility model discloses the advantage is, forms the cavity on the base plate, has enlarged the volume of the back chamber of MEMS sensor, and the air volume of back chamber increases promptly, and the sound wave that gets into from the sound inlet promotes MEMS sensor's vibrating diaphragm motion more easily to improve the sensitivity and the SNR of silicon microphone, can also improve the frequency response performance of silicon microphone simultaneously.

Description

Silicon microphone

Technical Field

The utility model relates to a micro-electromechanical system (MEMS) technical field especially relates to a silicon microphone.

Background

The MEMS (Micro-Electro-Mechanical System) technology is a high and new technology developed at a high speed in recent years, and it adopts an advanced semiconductor manufacturing process to implement the batch manufacturing of devices such as sensors and drivers, and compared with the corresponding conventional devices, the MEMS device has very obvious advantages in terms of volume, power consumption, weight and price. Major examples of applications of MEMS devices on the market include pressure sensors, accelerometers, and silicon microphones.

Silicon microphones, also known as MEMS microphones, are microphones fabricated based on MEMS technology. The MEMS microphone is made up of a MEMS sensor, an ASIC amplifier, an acoustic cavity, and a circuit board with RF suppression circuitry. The MEMS sensor chip is a micro capacitor formed by a silicon diaphragm and a silicon back plate, and can convert sound pressure change into capacitance change, and then the capacitance change is reduced by an ASIC chip and is converted into an electric signal, so that the sound-electricity conversion is realized.

The silicon diaphragm divides the sound cavity of the silicon microphone into two parts, the area between the sound inlet hole and the silicon diaphragm is a front chamber, and the rest part of the sound cavity is a rear chamber. The air volume of the rear chamber of the existing silicon microphone is small, the difficulty of pushing a silicon diaphragm to move is increased, the sensitivity of an MEMS sensor is reduced, the signal-to-noise ratio of the silicon microphone is reduced, the air volume of the front chamber is large, the resonant frequency is reduced, and the frequency response performance of the silicon microphone is influenced.

Therefore, how to increase the volume of the back chamber of the MEMS sensor of the silicon microphone and improve the sensitivity, the signal-to-noise ratio and the frequency response performance of the silicon microphone becomes a technical problem to be solved urgently.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that a silicon microphone is provided, its volume that can increase the back chamber of MEMS sensor improves sensitivity, signal-to-noise ratio and the frequency response performance of silicon microphone.

In order to solve the above problem, the present invention provides a silicon microphone, which includes: the shell is provided with a sound inlet hole; the base plate and the shell form an accommodating cavity, the sound inlet hole is communicated with the accommodating cavity, one surface of the base plate is provided with a concave cavity, and the concave cavity is provided with an opening; and the acoustic assembly is positioned in the accommodating cavity and arranged on the surface of the substrate, the acoustic assembly comprises a MEMS sensor, the MEMS sensor covers the opening, the concave cavity is used as an expanded rear chamber of the MEMS sensor, and the area between the sound inlet hole and the MEMS sensor is used as a front chamber of the MEMS sensor.

Furthermore, the base plate is of a concave configuration, the shell is a cover plate, and the shell covers the base plate to form the accommodating cavity.

Further, the shell is of a concave configuration, the substrate is a flat plate, and the shell is buckled on the substrate to form the accommodating cavity.

Further, the opening area of the opening is smaller than the area of the top of the cavity.

Further, the acoustic assembly further comprises an electrical chip, the electrical chip is arranged on the surface of the substrate, the MEMS sensor is electrically connected with the electrical chip, and the electrical chip is electrically connected to an external bonding pad through the substrate.

Further, the MEMS sensor and the electrical chip are arranged on the surface of the substrate in an inverted mode, and the MEMS sensor and the electrical chip are electrically connected through a circuit arranged in the substrate.

Further, the MEMS sensor and the electrical chip are arranged on the surface of the substrate in a normal mode, and the MEMS sensor and the electrical chip are electrically connected through a metal lead.

Further, the base plate still includes a backup pad, the backup pad is regarded as the upper plate of cavity, the opening runs through the backup pad, the MEMS sensor sets up in the backup pad, the MEMS sensor with the backup pad seals jointly the cavity.

Furthermore, a step structure is arranged at the edge of the concave cavity, and the supporting plate is erected on the step surface of the step structure.

Further, the electrical chip is disposed on the supporting plate, or the electrical chip is disposed on a step surface of the step structure.

Furthermore, a conductive connection structure is arranged in the substrate, and the electric chip is electrically connected with an external welding pad through the conductive connection structure.

Further, the electrical chip is electrically connected with the conductive connection structure through a metal lead; or the electric chip is electrically connected with the conductive connecting structure through a support plate, and a circuit is arranged in the support plate.

Further, the concave cavity is arranged on the surface of the substrate opposite to the sound inlet hole.

The utility model has the advantages of, form the cavity on the base plate, enlarged the volume of the back chamber of MEMS sensor, the air volume increase of back chamber promptly, the sound wave that gets into from the sound inlet promotes MEMS sensor's vibrating diaphragm motion more easily to improve the sensitivity and the SNR of silicon microphone, can also improve the frequency response performance of silicon microphone simultaneously.

Drawings

Fig. 1 is a schematic structural diagram of a first embodiment of the silicon microphone of the present invention;

fig. 2 is a schematic structural diagram of a second embodiment of the silicon microphone of the present invention;

fig. 3 is a schematic structural diagram of a third embodiment of the silicon microphone of the present invention;

fig. 4 is a schematic structural diagram of a fourth embodiment of the silicon microphone of the present invention;

fig. 5 is a schematic structural diagram of a fifth embodiment of the silicon microphone of the present invention.

Detailed Description

The following describes in detail a silicon microphone according to the present invention with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of a first embodiment of the silicon microphone of the present invention. Referring to fig. 1, the silicon microphone includes a housing 1, a substrate 2 and an acoustic assembly 3.

The housing 1 has a sound inlet hole 10. The sound inlet hole 10 penetrates through the housing 1, that is, the sound inlet hole 10 is a through hole. External sound air flows through the sound inlet hole 10 into the interior of the silicon microphone.

The substrate 2 and the housing 1 form a receiving cavity 100. In this embodiment, the substrate 2 has a concave configuration, the housing 1 is a cover plate, and the housing 1 covers the substrate 2 to form the accommodating cavity 100. In a second embodiment of the present invention, please refer to fig. 2, which is a schematic structural diagram of a second embodiment of the silicon microphone of the present invention, wherein the housing 1 has a concave configuration, the substrate 2 is a flat plate, and the housing 1 is fastened on the substrate 2 to form the accommodating cavity 100.

The sound inlet hole 10 is communicated with the accommodating chamber 100, external sound air flows through the sound inlet hole 10 into the accommodating chamber 100, and the accommodating chamber 100 is used as a sound chamber.

A surface of the substrate 2 has a cavity 20. An inner surface of the substrate 2 is recessed toward the outside of the substrate 2 to form a cavity 20. In the first embodiment, the inner surface of the substrate 2 opposite to the sound inlet 10 is recessed toward the outside of the substrate 2 to form the cavity 20, that is, the cavity 20 is disposed on the surface of the substrate 2 opposite to the sound inlet 10. In another embodiment of the present invention, the cavity 20 may be formed by recessing an inner surface of the substrate 2, which is not opposite to the sound inlet hole 10, toward an outside of the substrate 2, for example, the cavity 20 may be formed by recessing an inner surface of the substrate 2 toward the outside of the substrate 2.

The cavity 20 has an opening 20A. In the first embodiment, the opening 20A has an opening area smaller than the area of the top of the cavity 20.

In some embodiments of the present invention, the opening 20A may be formed by performing a mechanical milling process on the inside of the substrate 2 to form the cavity 20 and then removing a portion of the top of the cavity 20. In the first embodiment, the base plate 2 further includes a supporting plate 21, the supporting plate 21 covers the cavity 20, and the supporting plate 21 serves as an upper plate of the cavity 20. An opening penetrating the support plate 21 is formed in the support plate 21 as an opening 20A of the cavity 20. Specifically, in the first embodiment, the method for forming the cavity 20 includes: the base plate 2 is a Printed Circuit Board (PCB), a cavity 20 is formed on the base plate 2 through a mechanical milling process, the support plate 21 is fixed on the base plate 2 and covers the cavity 20, the support plate 21 serves as an upper plate of the cavity 20, and an opening 21 is formed in the support plate 21.

Further, in the first embodiment, a step structure 22 is provided at the edge of the cavity 20. The supporting plate 21 is erected on the step surface of the step structure 22, and the side wall of the step structure 22 can limit the supporting plate 21 to prevent the supporting plate from moving; and when the supporting plate 21 is installed, the step structure 22 can be used as a positioning mark to provide a reference for the installation of the supporting plate 21.

The acoustic assembly 3 is located in the accommodating cavity 100 and is disposed on the surface of the substrate 1. The acoustic assembly 3 comprises a MEMS sensor 31. The MEMS sensor 31 covers the opening 20A, that is, the cavity 20 is communicated with the internal rear chamber of the MEMS sensor 31, and the cavity 20 is sealed, so that the cavity 20 serves as an extended rear chamber of the MEMS sensor 31, and together with the internal rear chamber of the MEMS sensor 31, the cavity serves as a rear chamber of the MEMS sensor 31, thereby increasing the volume of the rear chamber of the MEMS sensor 31 and improving the sensitivity, signal-to-noise ratio and frequency response performance of the silicon microphone. The area between the sound inlet hole 10 and the MEMS sensor 31 serves as a front chamber of the MEMS sensor 31, and the external sound air flows through the sound inlet hole 10 into the front chamber to push the diaphragm of the MEMS sensor 31 to vibrate.

In the present embodiment, the MEMS sensor 31 is disposed on the support plate 21, and the support plate 21 supports the MEMS sensor 32. The supporting plate 21 and the MEMS sensor chip 31 jointly seal the cavity 20, so as to form a front chamber and a sealed rear chamber in the accommodating cavity 100, which are communicated with the outside.

The acoustic assembly 3 further comprises an electrical chip 32, the MEMS sensor 31 is electrically connected to the electrical chip 32, and the electrical chip 32 is electrically connected to an external pad (not shown in the drawings) through the substrate 2. The electrical chip 32 includes, but is not limited to, an Application Specific Integrated Circuit (ASIC) chip. The MEMS sensor 31 and the electrical chip 32 are packaged in the accommodating cavity 100. The MEMS sensor 31 converts the acoustic wave into a capacitance change, and the electrical chip 32 detects the capacitance change and converts it into an electrical signal to be output to an external pad.

The electrical chip 32 is arranged on the inner surface of the substrate 2. It may be located on the same surface of the substrate 2 as the MEMS sensor 31, or it may be located on a different surface of the substrate 2. In the first embodiment, the electrical chip 32 and the MEMS sensor 31 are located on the same surface of the substrate 2.

Further, in the first embodiment, the MEMS sensor 31 and the electrical chip 32 are both mounted on the support plate 21. The MEMS sensor 31 and the electrical chip 32 are electrically connected by a metal wire 33. A conductive connection structure 23 is disposed in the substrate 2, and the conductive connection structure 23 penetrates through the substrate 2 to be electrically connected with an external pad. The conductive connection mechanism 22 includes, but is not limited to, a conductive post. The electrical chip 32 is connected to the conductive connection structure 23 through a metal lead 34, and the conductive connection structure 23 is electrically connected to an external pad.

In a first embodiment, the electrical chip 32 is disposed on the supporting plate 21, and in another embodiment of the present invention, the electrical chip 32 is disposed on the step surface of the step structure 22. FIG. 3 is a schematic structural diagram of a silicon microphone according to a third embodiment of the present invention, please refer to

In a third embodiment, as shown in fig. 3, the electrical chip 32 is disposed on the step surface of the step structure 22, the electrically conductive connection structure 23 passes through the substrate region outside the step structure 22, and the electrical chip 32 is connected to the electrically conductive connection structure 23 through a metal wire 34.

In the first embodiment, the MEMS sensor 31 and the electrical chip 32 are electrically connected through a metal wire, and in another embodiment of the present invention, the MEMS sensor 31 and the electrical chip 32 are not electrically connected through a metal wire, but electrically connected through a flip chip.

Fig. 4 is a schematic structural diagram of a fourth embodiment of the silicon microphone of the present invention, please refer to fig. 4, in which the MEMS sensor 31 and the electrical chip 32 are both flip-chip mounted on the substrate 2, specifically, in this embodiment, the MEMS sensor 31 and the electrical chip 32 are both flip-chip mounted on the surface of the supporting plate 21, for example, the MEMS sensor 31 and the electrical chip 32 are flip-chip mounted on the surface of the supporting plate 21 through the conductive layer 35. The support plate 21 is a conductive substrate, and a circuit can be formed by wiring inside the conductive substrate. The MEMS sensor 31 and the electrical chip 32 are electrically connected through a circuit in the support plate 21. In the region of the step structure 22, the electrically conductive connection structure 23 is electrically connected to the support plate 21 through the substrate 2, and the electrical chip 32 is electrically connected to the electrically conductive connection structure 23 through a circuit in the support plate 21. Further, in the fourth embodiment, a plurality of the conductive connection structures 23 can be provided to connect different output terminals of the electrical chip 32 with external pads at different positions.

The present invention further provides a fifth embodiment of the silicon microphone, wherein the fifth embodiment is different from the fourth embodiment in that the electrical chip 32 is disposed at a different position.

Fig. 5 is a schematic structural diagram of a fifth embodiment of the silicon microphone of the present invention, please refer to fig. 5, wherein the electrical chip 32 is flip-chip mounted on the step surface of the step structure 22. In the region of the step structure 22, the conductive connection structure 23 passes through the substrate 2, and the pad at the bottom of the electrical chip 32 and the conductive connection structure 23 are directly connected through a conductive layer 35 and the like. In the present embodiment, the MEMS sensor 31 is flip-chip mounted on the support plate 21 having electrical conductivity, the output end of the support plate 21 can be electrically connected to the electrical chip 32, and the MEMS sensor 31 is electrically connected to the electrical chip 32 through the support plate 21. In other embodiments of the present invention, a circuit may be disposed at the step surface of the step structure 22 to electrically connect the output end of the supporting plate 21 with the electrical chip 32.

The utility model discloses the volume greatly increased of the back chamber of the MEMS sensor of silicon microphone has improved sensitivity, signal-to-noise ratio and the frequency response performance of silicon microphone greatly.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A silicon microphone, comprising:

the shell is provided with a sound inlet hole;

the base plate and the shell form an accommodating cavity, the sound inlet hole is communicated with the accommodating cavity, one surface of the base plate is provided with a concave cavity, and the concave cavity is provided with an opening;

and the acoustic assembly is positioned in the accommodating cavity and arranged on the surface of the substrate, the acoustic assembly comprises a MEMS sensor, the MEMS sensor covers the opening, the concave cavity is used as an expanded rear chamber of the MEMS sensor, and the area between the sound inlet hole and the MEMS sensor is used as a front chamber of the MEMS sensor.

2. A silicon microphone as claimed in claim 1 wherein the base plate is of concave configuration and the housing is a cover plate, the housing being fitted over the base plate to form the receiving cavity.

3. A silicon microphone as claimed in claim 1 wherein the housing is of concave configuration and the base plate is a flat plate, the housing being snap-fitted to the base plate to form the receiving cavity.

4. A silicon microphone as claimed in claim 1 wherein the opening has an opening area smaller than the area of the top of the cavity.

5. A silicon microphone as claimed in claim 1 wherein the acoustic assembly further comprises an electrical chip disposed on a surface of a substrate, the MEMS sensor being electrically connected to the electrical chip, the electrical chip being electrically connected to external pads through the substrate.

6. The silicon microphone of claim 5, wherein the MEMS sensor and the electrical chip are flip-chip mounted on the surface of the substrate, and the MEMS sensor and the electrical chip are electrically connected through a circuit mounted in the substrate.

7. A silicon microphone as claimed in claim 5 wherein the MEMS sensor and the electrical chip are mounted on the substrate surface, the MEMS sensor and the electrical chip being electrically connected by metal leads.

8. A silicon microphone as claimed in claim 5 wherein the base plate further comprises a support plate that is an upper plate of the cavity, the opening extending through the support plate, the MEMS sensor being disposed on the support plate, the MEMS sensor and the support plate together sealing the cavity.

9. A silicon microphone as claimed in claim 8 wherein there is a step formation at the edge of the cavity and the support plate is raised on a step face of the step formation.

10. A silicon microphone as claimed in claim 9 wherein the electronics chip is provided on the support plate or on a step face of the step structure.

11. A silicon microphone as claimed in claim 5 wherein conductive connection structures are provided in the substrate, the electrical chips being electrically connected to external pads through the conductive connection structures.

12. A silicon microphone as claimed in claim 11 wherein the electrical chip is electrically connected to the conductive connection structure by metal leads; or the electric chip is electrically connected with the conductive connecting structure through a support plate, and a circuit is arranged in the support plate.

13. A silicon microphone as claimed in claim 1 wherein the cavity is provided in the surface of the base plate opposite the sound inlet aperture.