CN111405402A

CN111405402A - Microphone structure

Info

Publication number: CN111405402A
Application number: CN202010213370.9A
Authority: CN
Inventors: 柏杨
Original assignee: AAC Acoustic Technologies Shenzhen Co Ltd
Current assignee: AAC Technologies Holdings Shenzhen Co Ltd
Priority date: 2020-03-24
Filing date: 2020-03-24
Publication date: 2020-07-10
Also published as: WO2021189508A1

Abstract

The invention provides a microphone structure, which comprises a substrate with a back cavity, a supporting piece arranged on the substrate and a vibrating diaphragm fixed on the supporting piece and positioned above the back cavity, wherein the vibrating diaphragm comprises a central part positioned at the central position and a boundary part which surrounds the central part and is fixed on the substrate, the boundary part extends to the upper part of the back cavity, and the thickness of the boundary part is greater than that of the central part. After the microphone structure is applied, the fracture critical value of the vibrating diaphragm can be improved, the working time of the vibrating diaphragm from initial microcrack development to the critical value is prolonged, the risk of the vibrating diaphragm fracture is reduced, the mechanical reliability of microphone devices is improved, and the service life of the microphone is prolonged.

Description

Microphone structure

[ technical field ] A method for producing a semiconductor device

The invention relates to the field of microphones, in particular to a microphone structure technology.

[ background of the invention ]

The microphone has wider application fields and higher requirements on the reliability of devices. The microphone chip structure mainly comprises a substrate structure with a back cavity, a vibrating diaphragm positioned on the upper part of the substrate and a fixed back plate structure. The membrane and the fixed backplate structure constitute a capacitive system. External sound pressure passes through the through holes in the backplate, causing the diaphragm to move, which changes the distance between the membrane and the backplate, which in turn changes the capacitance and ultimately converts into an electrical signal.

In the application scene of large sound pressure level and the mechanical reliability tests such as air blowing and dropping, if the vibrating diaphragm at the edge is in contact with the sharp back cavity boundary at the upper part of the substrate, microcracks are generated at the corresponding position of the vibrating diaphragm after the contact.

When repeated large sound pressure or blowing, falling and other conditions occur, the vibrating diaphragm can move back and forth between the back plate and the substrate structure, stress borne by the vibrating diaphragm is regarded as alternating stress, the initial microcrack can slowly expand under the action of the alternating stress, and after the initial microcrack exceeds a critical point, the vibrating diaphragm can be broken, so that the microphone chip is failed.

[ summary of the invention ]

The invention aims to provide a microphone structure, aiming at solving the problem that a microphone diaphragm is damaged under a large sound pressure level in the prior art.

The technical scheme of the invention is as follows: a microphone structure comprises a substrate with a back cavity, a supporting piece arranged on the substrate and a vibrating diaphragm fixed on the supporting piece and positioned above the back cavity, wherein the vibrating diaphragm comprises a central part positioned at a central position and a boundary part surrounding the central part and fixed on the substrate, the boundary part extends to the upper part of the back cavity, and the thickness of the boundary part is greater than that of the central part.

Furthermore, the substrate is provided with a side wall and a top wall, the side wall surrounds the side wall to form the back cavity, the top wall faces the diaphragm and is connected with the side wall, a substrate boundary is formed at the joint of the top wall and the side wall, and the substrate boundary is of a chamfer structure or a fillet structure.

Furthermore, the vibrating diaphragm further comprises a back plate arranged on the substrate, the back plate is positioned on one side of the vibrating diaphragm, which is far away from the back cavity, and the back plate is provided with a through hole penetrating through the back plate.

Furthermore, the support member comprises a back plate support member connecting the back plate and the substrate, and a vibrating diaphragm support member connecting the vibrating diaphragm and the substrate, and the back plate is arranged at an interval with the vibrating diaphragm through the back plate support member.

The invention has the beneficial effects that: the thickness of the boundary part of the vibrating diaphragm is increased to be larger than that of the central part, and the contact part of the substrate and the vibrating diaphragm is set to be a chamfer or fillet structure, so that the broken critical value of the vibrating diaphragm is improved when the vibrating diaphragm is in contact with the substrate in vibration, the working time of developing from an initial microcrack to the critical value is further prolonged, the risk of breakage of the vibrating diaphragm is reduced, the mechanical reliability level of a microphone device is improved, and the service life of the microphone is prolonged.

[ description of the drawings ]

FIG. 1 is a cross-sectional view of a microphone structure according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view of a microphone structure according to a second embodiment of the present invention;

FIG. 3 is a cross-sectional view of a microphone structure according to a third embodiment of the present invention;

FIG. 4 is a cross-sectional view of a microphone structure according to a fourth embodiment of the present invention;

[ detailed description ] embodiments

The invention is further described with reference to the following figures and embodiments.

Referring to fig. 1, fig. 1 is a cross-sectional view of a microphone structure according to a first embodiment of the invention. The invention provides a microphone structure, which comprises a substrate 1 with a back cavity 11, a support part 4 arranged on the substrate 1 and a diaphragm 2 fixed on the support part 4 and positioned above the back cavity 11, wherein the diaphragm 2 comprises a central part 21 positioned at the central position and a boundary part 22 surrounding the central part 21 and fixed on the substrate 1, the boundary part 22 extends to the upper part of the back cavity 11, and the thickness of the boundary part 22 is larger than that of the central part 21.

The substrate 1 has a side wall 111 enclosing the back cavity 11 and a top wall 112 facing the diaphragm, where the top wall and the side wall are connected to form a substrate boundary 113.

In the process of back and forth movement of the diaphragm 2 caused by sound pressure or airflow, the boundary part 22 of the diaphragm 2 is in contact with the substrate boundary 113 of the substrate 1, and the diaphragm 2 bears alternating stress to generate micro cracks at the corresponding position of the diaphragm 2. In the present embodiment, the diaphragm 2 may be a piezoelectric diaphragm.

Referring to fig. 2, fig. 2 is a cross-sectional view of a microphone structure according to a second embodiment of the invention. In this embodiment, the microphone structure further includes a back plate 3 mounted on the substrate 1, the back plate 3 is located on a side of the diaphragm 2 away from the back cavity 11, and the back plate 3 is provided with a through hole 31 penetrating therethrough. The diaphragm 2 and the backplate 3 structure constitute a capacitance system. The external sound pressure causes the diaphragm 2 to move, which changes the distance between the diaphragm 2 and the backplate 3, which in turn changes the capacitance and ultimately converts the acoustic signal into an electrical signal.

Further, the microphone structure includes a supporting member 4, the boundary portion 22 is fixed to the substrate 1 through the supporting member 4, and the substrate boundary 113 may be configured as a chamfered structure 1131 or a rounded structure 1132.

The boundary portion 22 is spaced apart from the substrate 1 by a support member 4, which provides a vibration space for the vibration of the diaphragm 2, and the support member 4 is provided to the top wall 111. The supporting member 4 is disposed on the substrate wall 11 and does not contact the substrate boundary 113, which is beneficial to improving the overall stability.

Referring to fig. 3, fig. 3 is a cross-sectional view of a microphone structure according to a third embodiment of the present invention. As an alternative embodiment, it differs from the second embodiment only in that the substrate boundary 113 is a chamfered structure 1131.

Referring to fig. 4, fig. 4 is a cross-sectional view of a microphone structure according to a fourth embodiment of the invention. As an alternative embodiment, it differs from the second embodiment only in that the substrate boundary 113 is a fillet structure 1132.

On the basis that the thickness of the boundary portion 22 of vibrating diaphragm 2 is greater than the thickness of central part 21, basement boundary 113 adopts chamfer structure 1131 or fillet structure 1132, compare with original sharp-pointed structure, more can reduce the size that produces the microcrack in vibrating diaphragm 2, avoid because the great quick fracture that brings of crackle, prolonged the effective operating time of vibrating diaphragm, be favorable to avoiding the vibrating diaphragm 2 microcrack that corresponds the position, better reduction vibrating diaphragm 2 emergence cracked risk.

Specifically, the support member 4 includes a backplate support member 41 connecting the backplate 3 and the substrate 1, and a diaphragm support member 42 connecting the diaphragm 2 and the substrate 1, and the backplate 3 and the diaphragm 2 are arranged at an interval through the backplate support member 41. Specifically, the back plate support member 41 can further reinforce the diaphragm 2, which is beneficial to improving the stability of the diaphragm 2 and avoiding noise generation. In this embodiment, the backing plate support 41 may be deposited from a backing plate material.

It will be appreciated that a portion of the border portion 22 is located above the substrate 1 and another portion extends above the back cavity 11. Since the boundary portion 22 and the base boundary 113 may rub against each other during repeated mechanical reliability tests such as high sound pressure, air blowing, dropping, etc., the boundary portion 22 has a large thickness, which is advantageous for prolonging the life of the diaphragm 2.

The invention can be applied to various microphone chips with a substrate 1, a diaphragm 2 and a back cavity 12 structure, including MEMES microphones, piezoelectric microphones and optical microphones.

In the microphone structure, the thickness of the boundary part of the vibrating diaphragm is increased to be larger than that of the central part, and the contact part of the substrate and the vibrating diaphragm is set to be the chamfer or fillet structure, so that the fracture critical value of the vibrating diaphragm when contacting with the substrate in vibration is improved, the working time from initial microcrack development to the critical value is prolonged, the risk of the vibrating diaphragm fracture is reduced, the mechanical reliability level of a microphone device is improved, and the service life of the microphone is prolonged.

While the foregoing is directed to embodiments of the present invention, it will be understood by those skilled in the art that various changes may be made without departing from the spirit and scope of the invention.

Claims

1. A microphone structure comprises a substrate with a back cavity, a supporting piece arranged on the substrate and a vibrating diaphragm fixed on the supporting piece and positioned above the back cavity, and is characterized in that the vibrating diaphragm comprises a central part positioned at a central position and a boundary part surrounding the central part and fixed on the substrate, the boundary part extends to the upper part of the back cavity, and the thickness of the boundary part is greater than that of the central part.

2. The microphone structure of claim 1, wherein the base has a side wall surrounding the back cavity and a top wall facing the diaphragm and connected to the side wall, and a junction of the top wall and the side wall forms a base boundary, and the base boundary is a chamfered structure or a rounded structure.

3. A microphone structure as claimed in claim 1 or 2, further comprising a backplate mounted on the substrate, the backplate being located on a side of the diaphragm remote from the back cavity, the backplate being provided with a through-hole therethrough.

4. The microphone structure of claim 3, wherein the support member comprises a backplate support member connecting the backplate and the substrate, and a diaphragm support member connecting the diaphragm and the substrate, the backplate being spaced apart from the diaphragm by the backplate support member.