CN113365197A - MEMS microphone and manufacturing method thereof - Google Patents

MEMS microphone and manufacturing method thereof Download PDF

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Publication number
CN113365197A
CN113365197A CN202110728000.3A CN202110728000A CN113365197A CN 113365197 A CN113365197 A CN 113365197A CN 202110728000 A CN202110728000 A CN 202110728000A CN 113365197 A CN113365197 A CN 113365197A
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Prior art keywords
hole
diaphragm
substrate
vibrating diaphragm
mems microphone
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CN202110728000.3A
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CN113365197B (en
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周宗燐
卓彥萱
邱冠勋
王喆
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Goertek Microelectronics Inc
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Goertek Microelectronics Inc
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H04R19/04—Microphones
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81B—MICROSTRUCTURAL DEVICES OR SYSTEMS, e.g. MICROMECHANICAL DEVICES
    • B81B7/00—Microstructural systems; Auxiliary parts of microstructural devices or systems
    • B81B7/02—Microstructural systems; Auxiliary parts of microstructural devices or systems containing distinct electrical or optical devices of particular relevance for their function, e.g. microelectro-mechanical systems [MEMS]
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00015—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems
    • B81C1/00134—Manufacture or treatment of devices or systems in or on a substrate for manufacturing microsystems comprising flexible or deformable structures
    • B81C1/00158—Diaphragms, membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00349—Creating layers of material on a substrate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B81—MICROSTRUCTURAL TECHNOLOGY
    • B81C—PROCESSES OR APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OR TREATMENT OF MICROSTRUCTURAL DEVICES OR SYSTEMS
    • B81C1/00—Manufacture or treatment of devices or systems in or on a substrate
    • B81C1/00436—Shaping materials, i.e. techniques for structuring the substrate or the layers on the substrate
    • B81C1/00523—Etching material
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H04R19/005—Electrostatic transducers using semiconductor materials
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
    • H04R2201/003—Mems transducers or their use

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Computer Hardware Design (AREA)
  • Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)
  • Pressure Sensors (AREA)

Abstract

The invention provides an MEMS microphone, which comprises a packaging structure formed by a shell and a substrate, wherein an MEMS chip is arranged in the packaging structure and comprises a substrate, a vibrating diaphragm and a back electrode, wherein the vibrating diaphragm and the back electrode are arranged on the substrate; the back pole is provided with a limiting part for limiting the upward movement of the vibrating diaphragm, the central column is used for limiting the upward movement range of the vibrating diaphragm, and the limiting part and the central column limit the displacement of the vibrating diaphragm under the action of external sound pressure. The invention can solve the problem that the performance of the MEMS microphone is influenced by the stress generated in the central area and the peripheral edge position due to the excessive deformation of the diaphragm of the MEMS chip in the traditional MEMS microphone structure.

Description

MEMS microphone and manufacturing method thereof
Technical Field
The invention relates to the technical field of electroacoustic conversion, in particular to an MEMS microphone and a manufacturing method thereof.
Background
An MEMS (Micro electro mechanical Systems ) microphone is an electric transducer manufactured by Micro machining technology, and has the characteristics of small volume, good frequency response, low noise, and the like. With the development of miniaturization and thinning of electronic devices, MEMS microphones are increasingly widely used for these devices.
The existing MEMS microphone structure comprises a packaging structure consisting of a metal shell and a substrate, an ASIC chip and an MEMS chip are arranged on the substrate inside the packaging structure, and a sound inlet communicated with the outside is also arranged on the substrate, wherein the MEMS chip comprises a substrate, a vibrating diaphragm and a back electrode, the vibrating diaphragm and the back electrode are arranged on the substrate, the vibrating diaphragm and the back electrode form a capacitor, and the vibrating diaphragm vibrates along with the change of sound pressure to sense sound. In the embodiment shown in fig. 4-1 and 4-2, the back hole formed by the MEMS chip of the MEMS microphone is a fan-shaped structure, the fan-shaped back hole structure is formed by the central pillar 11 of the silicon substrate and the connecting pillars at both sides, and the top end of the center 11 of the back hole, the diaphragm layer 3, and the central area of the back plate layer (the crystalline silicon back plate 5 and the silicon nitride back plate) are connected, so that the diaphragm forms a doughnut-type structure. When the diaphragm is subjected to the pressure of blowing air, the diaphragm is easy to impact or cling to the back plate, so that the diaphragm is damaged due to stress generated in the central area and the peripheral edge position due to excessive deformation of the diaphragm.
In order to solve the above problems, the present invention provides a novel MEMS microphone and a method for manufacturing the same.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide a MEMS microphone and a method for manufacturing the same, so as to solve the problem that the existing MEMS microphone structure causes stress in the central area and the peripheral edge position due to excessive deformation of the diaphragm of the MEMS chip, thereby affecting the performance of the MEMS microphone.
The MEMS microphone provided by the invention comprises a packaging structure formed by a shell and a substrate, wherein an MEMS chip is arranged on the substrate in the packaging structure, the MEMS chip comprises a substrate, a vibrating diaphragm and a back electrode, the vibrating diaphragm and the back electrode are arranged on the substrate, the MEMS microphone is characterized in that,
the substrate comprises a connecting column and a central column positioned inside the connecting column, the connecting column and the central column form a back hole on the substrate, wherein,
a through hole is formed in the vibrating diaphragm above the central column, and the through hole is used for releasing restraint of the middle area of the vibrating diaphragm;
the back pole is provided with a limiting part for limiting the upward movement of the vibrating diaphragm, the central column is used for limiting the upward movement range of the vibrating diaphragm, and the limiting part and the central column limit the displacement of the vibrating diaphragm under the action of the external sound pressure.
In addition, it is preferable that the MEMS chip further includes a thermal oxidation layer, wherein,
the thermal oxidation layer is arranged on the substrate, and the vibrating diaphragm is arranged on the thermal oxidation layer.
In addition, it is preferable that the MEMS chip further includes a sacrificial layer, wherein,
the sacrificial layer is arranged between the diaphragm and the back electrode, and the diaphragm and the back electrode are used as electrode plates for forming the variable capacitor.
In addition, it is preferable that a metal layer is provided on the back electrode, wherein,
the metal layer serves as an electrode plate of the back electrode.
In addition, preferably, the metal layer is a chromium metal layer or a gold metal layer.
In addition, the preferable scheme is that the back hole is an annular back hole or a fan-shaped back hole; the through hole is an annular through hole.
In addition, preferably, the substrate corresponding to the vibrating diaphragm is provided with a sound hole communicated with the outside, and the sound hole is communicated with the back hole; wherein the content of the first and second substances,
the sound hole is used for transmitting external sound pressure to a vibrating diaphragm inside the packaging structure, so that the vibrating diaphragm generates vibration.
The invention also provides a manufacturing method of the MEMS microphone, which comprises the following steps:
carrying out thermal oxidation on the substrate, and enabling the substrate to react with an oxidant to form a thermal oxidation layer;
depositing polycrystalline silicon on the thermal oxidation layer to serve as a vibrating diaphragm, and etching a through hole on the vibrating diaphragm, wherein the through hole is used for limiting the restraint of a middle area for releasing the vibrating diaphragm;
depositing polyethylene oxide on the diaphragm to serve as a sacrificial layer;
depositing silicon nitride on the sacrificial layer to serve as a first insulating layer, and etching a first groove on the first insulating layer;
depositing polycrystalline silicon on the first insulating layer to serve as a back electrode, wherein the polycrystalline silicon deposited in the first groove forms a limiting part, and the limiting part is used for limiting the upward movement range of the diaphragm;
depositing silicon nitride on the back electrode to serve as a second insulating layer, etching the second insulating layer, and extending a groove formed by etching to the back electrode;
arranging a metal layer in the formed groove, wherein the metal layer is an electrode plate of the back electrode;
and etching the substrate, and forming a central column at a position corresponding to the middle area of the diaphragm so that the substrate forms a back hole.
Preferably, the metal layer is formed by sputtering.
In addition, preferably, the back electrode is etched to form a deep groove, and the deep groove extends to the diaphragm.
From the above technical solutions, in the MEMS microphone and the manufacturing method thereof provided by the present invention, the diaphragm located above the central pillar of the substrate is provided with the through hole, that is: the position that is close to central post at the vibrating diaphragm sets up the through-hole to release central authorities and restrain, and set up the scope that is used for spacing vibrating diaphragm vibration upwards on the back of the body utmost point, central post is used for the scope of spacing vibrating diaphragm vibration downwards, and consequently spacing vibrating diaphragm is in jointly with central post displacement volume under the effect of outside acoustic pressure, thereby solve the problem of the stress concentration of vibrating diaphragm central point.
To the accomplishment of the foregoing and related ends, one or more aspects of the invention comprise the features hereinafter fully described. The following description and the annexed drawings set forth in detail certain illustrative aspects of the invention. These aspects are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Further, the present invention is intended to include all such aspects and their equivalents.
Drawings
Other objects and results of the present invention will become more apparent and more readily appreciated as the same becomes better understood by reference to the following description and appended claims, taken in conjunction with the accompanying drawings. In the drawings:
fig. 1 is a schematic structural diagram of a MEMS microphone according to an embodiment of the present invention;
FIG. 2-1 is a schematic structural diagram of a MEMS chip according to an embodiment of the present invention;
FIG. 2-2 is an enlarged schematic view of a portion A of a MEMS chip according to an embodiment of the present invention;
FIG. 3 is a flow chart of a method for fabricating a MEMS microphone according to an embodiment of the invention;
FIG. 4-1 is a schematic structural diagram of a conventional MEMS chip;
FIG. 4-2 is a schematic diagram of a back hole sector structure of the MEMS chip of FIG. 4-1.
Wherein the reference numerals include: 1. the structure comprises a substrate, 11, a central column, 2, a thermal oxidation layer, 3, a vibrating diaphragm, 31, a through hole, 4, a sacrificial layer, 5, a back electrode, 6, an insulating layer (a first insulating layer and a second insulating layer), 7, a metal layer, 10, a substrate, 20, a shell, 30, an ASIC chip, 40, an MEMS chip, 50 and a sound hole.
The same reference numbers in all figures indicate similar or corresponding features or functions.
Detailed Description
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more embodiments. It may be evident, however, that such embodiment(s) may be practiced without these specific details.
The MEMS microphone structure aims at the problem that the performance of the MEMS microphone is affected due to the fact that the diaphragm of the MEMS chip is excessively deformed to generate stress in the central area and the peripheral edge position in the existing MEMS microphone structure. The invention provides a novel MEMS microphone and a manufacturing method thereof, so that the problems of the existing MEMS microphone are solved.
Specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
For illustrating the structure of the MEMS microphone provided by the present invention, fig. 1 to 2-2 are exemplarily labeled from the structures of different MEMS microphones, respectively. In particular, fig. 1 shows a MEMS microphone structure according to an embodiment of the invention; FIG. 2-1 illustrates a MEMS chip structure according to an embodiment of the present invention; fig. 2-2 shows a portion a enlarged structure of a MEMS chip according to an embodiment of the invention.
As shown in fig. 1, fig. 2-1 and fig. 2-2 together, the MEMS microphone provided by the present invention includes a package structure formed by a housing 20 and a substrate 10, a MEMS chip 40 and an ASIC chip 30 are disposed inside the package structure, and the MEMS chip 40 includes a substrate 1 and a diaphragm 3 disposed on the substrate 1. The substrate 1 comprises a connecting column and a central column 11 positioned inside the connecting column, the connecting column and the central column 11 form a back hole on the substrate 1, wherein a through hole 31 is formed in the vibrating diaphragm 3 positioned above the central column 11, the vibrating diaphragm 3 positioned above the central column 11 is provided with the through hole 31, and the through hole 31 is used for releasing restraint of the middle area of the vibrating diaphragm 3; a limiting part for limiting the upward movement of the diaphragm 3 is arranged on the back electrode 5, the central column 11 is used for limiting the upward movement range of the diaphragm 3, and the limiting part and the central column 11 limit the displacement of the diaphragm 3 under the action of external sound pressure.
The shape of the back hole can be set according to actual requirements in specific application, and the shape of the back hole is not limited to be only annular or fan-shaped, but also can be made into any other required shape.
Wherein, the MEMS chip 40 and the ASIC chip 30 may both be disposed on the substrate 10, as in the embodiment shown in fig. 1; further, one of the MEMS chip 40 and the ASIC chip 30 is disposed on the substrate 10, and the two chips are disposed to be superposed.
In the embodiment of the present invention, the back hole is communicated with the outside, and the external sound pressure acts on the diaphragm 3 through the back hole, where it should be noted that the external sound pressure not only can integrate the back hole action and the diaphragm, but also can act on the diaphragm through other directions, that is: the external sound pressure in the invention is not only entered into the MEMS microphone through the back hole, but the path of the external sound pressure entered into the MEMS microphone is not specifically limited.
In the embodiment shown in fig. 2-1, the MEMS chip includes, from bottom to top, a substrate 1, a thermal oxide layer 2, a diaphragm 3, a sacrificial layer 4, a back electrode 5, an insulating layer 6, and a metal layer 7, where the insulating layer 6 includes a first insulating layer and a second insulating layer, where the first insulating layer is disposed between the sacrificial layer 4 and the back electrode 5, and the second insulating layer is disposed above the back electrode 5, that is, the back electrode 5 is disposed between the first insulating layer and the second insulating layer, where a groove is disposed on the second insulating layer, the groove extends to the back electrode 5, and the metal layer 7 is disposed on the back electrode 5 through the groove of the second insulating layer.
Wherein, thermal oxidation layer 2 is arranged on substrate 1, and vibrating diaphragm 3 is arranged on thermal oxidation layer 2. The sacrifice layer 4 is provided between the diaphragm 3 and the back electrode 5, and the diaphragm 3 and the back electrode 5 serve as electrode plates forming a variable capacitor. Since the metal layer 7 is provided on the back electrode 5, the metal layer 7 serves as an electrode plate of the back electrode 5. The metal layer can be a chromium metal layer, and can also be designed into a gold metal layer according to requirements, and in specific application, the metal layer made of a proper material is selected according to requirements.
In the embodiment shown in fig. 2-2, the diaphragm 3 disposed above the center pillar 11 is a center region of the diaphragm, and the edge of the center position of the diaphragm 3 is provided with a through hole 31, that is, the through hole 31 is disposed at a position of the diaphragm 3 close to the center pillar 11, which can release the central constraint of the diaphragm, and a groove extending to the diaphragm is made on the back electrode 5, in this design structure, the center pillar 11 and the through hole 31 are combined with each other to limit the displacement of the diaphragm 3 (the center position of the diaphragm) located above the center pillar 11 under the action of external sound pressure, thereby solving the problem of stress concentration at the center position of the diaphragm.
As shown in fig. 2-2, the through hole 31 is an annular through hole, and the annular through hole is etched on the edge of the center of the diaphragm by etching, so as to solve the problem of stress concentration at the center of the diaphragm. In a specific application, the through hole may be an arc-shaped through hole according to practical situations, and in the embodiment of the present invention, the shape of the through hole 31 is not limited to the annular through hole and the arc-shaped through hole, as long as the central constraint of the diaphragm is released, so as to solve the problem of stress concentration at the central position of the diaphragm.
In the embodiment of the invention, in the MEMS microphone, the substrate 10 corresponding to the diaphragm 3 of the MEMS chip 40 is provided with the acoustic hole 50 communicated with the outside, and the acoustic hole 50 is communicated with the annular back hole; the sound hole is used for transmitting external sound pressure to the diaphragm 3 of the MEMS chip 40 inside the package structure, so that the diaphragm 3 vibrates.
According to the MEMS microphone provided by the invention, the through hole is formed in the vibrating diaphragm above the central column of the substrate, so that the central constraint of the vibrating diaphragm is released, and under the mutual combination of the central column and the through hole, the displacement action of the vibrating diaphragm above the central column under the action of external sound pressure is limited, so that the problem of stress concentration at the central position of the vibrating diaphragm is solved.
In the following description, for the sake of clarity and conciseness, a number of process details, such as devices, conditions, parameters, etc., which are considered to be well known to those skilled in the art, are omitted. The manufacturing method of the MEMS microphone provided by the invention comprises the following steps:
s310: and carrying out thermal oxidation on the substrate, and reacting the substrate with an oxidant to form a thermal oxidation layer.
The substrate is made of a polycrystalline silicon material, and the polycrystalline silicon of the substrate reacts with an oxidant to generate silicon dioxide through substrate thermal oxidation. The thermal oxidation process may be: carrying out N-type doping or P-type doping on the substrate layer in advance to make the surface resistance smaller; then, the formed silicon dioxide is subjected to selective ion implantation with boron ions, arsenic ions, phosphorus ions, or the like, and the implanted ions are annealed to form a thermal oxide layer. In the embodiment of the present invention, the formation of the thermal oxidation layer is not limited to the above-described process.
And etching the thermal oxide layer to form a plurality of grooves, wherein the formed grooves are prepared for the next step.
S320: and depositing polycrystalline silicon on the thermal oxidation layer to serve as a vibrating diaphragm, and etching the vibrating diaphragm to form a through hole, wherein the through hole is used for limiting the restraint of the middle area for releasing the vibrating diaphragm.
And depositing polycrystalline silicon on the thermal oxidation layer forming the plurality of grooves to serve as a vibrating diaphragm, and etching the position, close to the central column, of the vibrating diaphragm to form a through hole, wherein the design of the through hole releases the central constraint of the vibrating diaphragm.
S330: depositing polyethylene oxide on the diaphragm to serve as a sacrificial layer; depositing silicon nitride as a first insulating layer on the sacrificial layer.
And depositing polyethylene oxide on the diaphragm etched with the through holes to serve as a sacrificial layer, etching a plurality of grooves on the sacrificial layer, wherein the grooves are different in depth, and the deeper grooves are formed by secondary etching.
S340: and depositing silicon nitride on the sacrificial layer to serve as a first insulating layer, and etching a first groove on the first insulating layer.
Depositing silicon nitride on the sacrificial layer etched with the grooves to serve as a first insulating layer, etching the first insulating layer and the sacrificial layer to form the grooves, wherein some grooves extend to the position of the diaphragm to prepare for forming through holes of the diaphragm above the central column.
S350: and depositing polycrystalline silicon on the first insulating layer to serve as a back electrode, wherein the polycrystalline silicon deposited in the first groove forms a limiting part, and the limiting part is used for limiting the upward movement range of the diaphragm.
And depositing polycrystalline silicon on the first insulating layer etched with the grooves to serve as a back electrode, and etching the back electrode to form the grooves, so that the back electrode is embedded in the insulating layer.
S360: and depositing a second insulating layer on the back electrode, etching the second insulating layer, and extending the etched groove to the back electrode.
Wherein, deposit silicon nitride on the back of the body pole that has a plurality of recesses of sculpture, as the second insulating layer, owing to the setting of recess on the back of the body pole for the back of the body pole is buried underground in the insulating layer, promptly: the first insulating layer and the second insulating layer are arranged in the groove of the back pole, so that a complete insulating layer is formed.
S370: and arranging a metal layer in the formed groove, wherein the metal layer is an electrode plate of the back electrode.
Because the second insulating layer is etched to the position of the back electrode, a metal layer is formed at the position in a sputtering mode, and the metal layer is an electrode plate of the back electrode; and etching the back electrode to form a groove, wherein the groove extends to the vibrating diaphragm.
S380: and etching the substrate, and forming a central column at a position corresponding to the middle area of the diaphragm so that the substrate forms a back hole.
And etching the substrate to form a back hole with a connecting column and a central column, wherein the central column is used for limiting the upward movement range of the diaphragm, and the central column and the limiting column formed in the step S350 jointly limit the displacement of the diaphragm under the action of external sound pressure. And after the substrate is etched, removing part of the structure in the sacrificial layer to form the MEMS chip.
The embodiment of the manufacturing process describes the production process flow of the MEMS microphone more precisely, and a through hole is etched in the diaphragm located above the central pillar of the substrate, so as to release the central constraint of the diaphragm and limit the displacement of the diaphragm located above the central pillar under the action of external sound pressure; the annular through hole is combined with the central column, so that the stress problem of the center position of the diaphragm is solved.
As can be seen from the foregoing embodiments, in the MEMS microphone and the method for manufacturing the same according to the present invention, the diaphragm located above the central pillar of the substrate is provided with the through hole, that is: the position that is close to central post at the vibrating diaphragm sets up the through-hole to release central authorities and restrain, and set up the scope that is used for spacing vibrating diaphragm vibration upwards on the back of the body utmost point, central post is used for the scope of spacing vibrating diaphragm vibration downwards, and consequently spacing vibrating diaphragm is in jointly with central post displacement volume under the effect of outside acoustic pressure, thereby solve the problem of the stress concentration of vibrating diaphragm central point.
The MEMS microphone and the method of fabricating the same proposed according to the present invention are described above by way of example with reference to the accompanying drawings. However, it will be appreciated by those skilled in the art that various modifications may be made to the MEMS microphone and the method of fabricating the same without departing from the scope of the invention. Therefore, the scope of the present invention should be determined by the contents of the appended claims.

Claims (10)

1. An MEMS microphone comprises a packaging structure formed by a shell and a substrate, an MEMS chip is arranged in the packaging structure, the MEMS chip comprises a substrate, a diaphragm arranged on the substrate and a back electrode, and the MEMS microphone is characterized in that,
the substrate comprises a connecting column and a central column positioned inside the connecting column, the connecting column and the central column form a back hole on the substrate, wherein,
a through hole is formed in the vibrating diaphragm above the central column, and the through hole is used for releasing restraint of the middle area of the vibrating diaphragm;
the back pole is provided with a limiting part for limiting the upward movement of the vibrating diaphragm, the central column is used for limiting the downward movement range of the vibrating diaphragm, and the limiting part and the central column limit the displacement of the vibrating diaphragm under the action of external sound pressure.
2. The MEMS microphone of claim 1,
the MEMS chip further comprises a thermal oxide layer, wherein,
the thermal oxidation layer is arranged on the substrate, and the vibrating diaphragm is arranged on the thermal oxidation layer.
3. The MEMS microphone of claim 1,
the MEMS chip further comprises a sacrificial layer, wherein,
the sacrificial layer is arranged between the diaphragm and the back electrode, and the diaphragm and the back electrode are used as electrode plates for forming the variable capacitor.
4. The MEMS microphone of claim 1,
a metal layer is disposed on the back electrode, wherein,
the metal layer serves as an electrode plate of the back electrode.
5. The MEMS microphone of claim 4,
the metal layer is a chromium metal layer or a gold metal layer.
6. The MEMS microphone of claim 1,
the back hole is an annular back hole or a fan-shaped back hole;
the through hole is an annular through hole.
7. The MEMS microphone of claim 1,
the substrate corresponding to the vibrating diaphragm is provided with a sound hole communicated with the outside, and the sound hole is communicated with the back hole; wherein the content of the first and second substances,
the sound hole is used for transmitting external sound pressure to a vibrating diaphragm inside the packaging structure, so that the vibrating diaphragm generates vibration.
8. A method for manufacturing a MEMS microphone is characterized by comprising the following steps:
carrying out thermal oxidation on the substrate, and enabling the substrate to react with an oxidant to form a thermal oxidation layer;
depositing polycrystalline silicon on the thermal oxidation layer to serve as a vibrating diaphragm, and etching a through hole on the vibrating diaphragm, wherein the through hole is used for limiting the restraint of a middle area for releasing the vibrating diaphragm;
depositing polyethylene oxide on the diaphragm to serve as a sacrificial layer;
depositing silicon nitride on the sacrificial layer to serve as a first insulating layer, and etching a first groove on the first insulating layer;
depositing polycrystalline silicon on the first insulating layer to serve as a back electrode, wherein the polycrystalline silicon deposited in the first groove forms a limiting part, and the limiting part is used for limiting the upward movement range of the diaphragm;
depositing silicon nitride on the back electrode to serve as a second insulating layer, etching the second insulating layer, and extending a groove formed by etching to the back electrode;
arranging a metal layer in the formed groove, wherein the metal layer is an electrode plate of the back electrode;
and etching the substrate, and forming a central column at a position corresponding to the middle area of the diaphragm so that the substrate forms a back hole.
9. The method of manufacturing a MEMS microphone according to claim 8,
the metal layer is formed by sputtering.
10. The method of manufacturing a MEMS microphone according to claim 8,
and etching the back electrode to form a depth groove, wherein the depth groove extends to the vibrating diaphragm.
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