WO2024139572A1

WO2024139572A1 - Optical microphone and manufacturing method therefor

Info

Publication number: WO2024139572A1
Application number: PCT/CN2023/125475
Authority: WO
Inventors: 潘汶; 章志强; 陈嘉伟; 苏杰
Original assignee: Oppo广东移动通信有限公司; 清华大学
Priority date: 2022-12-28
Filing date: 2023-10-19
Publication date: 2024-07-04
Also published as: CN116074715A

Abstract

An optical microphone and a manufacturing method therefor. The optical microphone comprises a microphone diaphragm and a photoelectric conversion assembly; the microphone diaphragm comprises a vibration membrane and a grating which are spaced apart from each other; and a sound inlet hole is formed in the vibration membrane. The photoelectric conversion assembly is provided on the side of the grating away from the vibration film; the photoelectric conversion assembly comprises a light source and a detector; the light source is used for emitting light towards the microphone diaphragm; and the detector is used for receiving the light reflected from the microphone diaphragm and converting an optical signal into an electric signal.

Description

Optical microphone and method for manufacturing the same

This application claims the priority of the Chinese patent application filed with the China Patent Office on December 28, 2022, with application number 202211701711.2 and invention name “Optical Microphone and Its Manufacturing Method”, the entire contents of which are incorporated by reference in this application.

Technical Field

The present application relates to the field of electronic technology, and in particular to an optical microphone and a method for manufacturing the same.

Background technique

Microphone is a common sound signal collection tool in people's daily life. With the gradual development of microphone technology, the application fields of microphones are also expanding. It has begun to undertake many new applications such as acoustic sensing, speech recognition, sonar detection, ultrasonic non-destructive testing, etc., and has played an important role in people's livelihood, scientific research, medical care, industry, national defense and other fields.

A traditional microphone includes a back plate and a diaphragm spaced apart from the back plate. The diaphragm vibrates under the action of sound waves, and voltage changes are generated by changing the distance between the back plate and the diaphragm, thereby achieving sound-to-electricity conversion.

Summary of the invention

An embodiment of the present application provides an optical microphone and a method for manufacturing the same. The optical microphone can convert an acoustic signal into an optical signal, and then convert the optical signal into an electrical signal, thereby realizing acoustic-electrical conversion. Moreover, the sensitivity of the optical microphone is greater than 100mV/Pa, far exceeding the sensitivity of traditional microphones. In addition, the optical microphone is small in size and easy to carry.

In a first aspect, an embodiment of the present application provides an optical microphone, comprising:

A microphone diaphragm, the microphone diaphragm comprising a vibrating film and a grating arranged at intervals, and a sound inlet hole is provided on the vibrating film;

The photoelectric conversion component is arranged on the side of the grating away from the vibration film, and the photoelectric conversion component includes a light source and a detector. The light source is used to emit light toward the microphone diaphragm, and the detector is used to receive the light reflected from the microphone diaphragm and convert the optical signal into an electrical signal.

In a second aspect, an embodiment of the present application provides a method for manufacturing an optical microphone, comprising:

A microphone diaphragm and a photoelectric conversion component are provided, wherein the microphone diaphragm includes a vibration film and a grating arranged at intervals, and a sound inlet hole is provided on the vibration film; the photoelectric conversion component includes a light source and a detector, wherein the light source is used to emit light toward the microphone diaphragm, and the detector is used to receive light reflected from the microphone diaphragm and convert the light signal into an electrical signal;

The microphone diaphragm and the photoelectric conversion component are connected so that the photoelectric conversion component is arranged on a side of the grating away from the vibration film to obtain an optical microphone.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for describing the embodiments.

FIG. 1 is a schematic diagram of the structure of an optical microphone provided in an embodiment of the present application.

FIG. 2 is a schematic diagram of the structure of a microphone diaphragm provided in an embodiment of the present application.

FIG. 3 is a schematic top view of a vibrating film provided in an embodiment of the present application.

FIG. 4 is a bottom view schematic diagram of the first inorganic layer provided in an embodiment of the present application.

FIG. 5 is a schematic diagram of a partial structure of a photoelectric conversion component provided in an embodiment of the present application.

FIG. 6 is a schematic top view of a photoelectric conversion component provided in an embodiment of the present application.

FIG. 7 is a flow chart of a method for manufacturing an optical microphone provided in an embodiment of the present application.

FIG8 is a schematic diagram after a first inorganic layer is formed on a first substrate according to an embodiment of the present application.

FIG. 9 is a schematic diagram of the first inorganic layer after patterning according to an embodiment of the present application.

FIG. 10 is a schematic diagram after a first electrode is formed on a first inorganic layer according to an embodiment of the present application.

FIG. 11 is a schematic diagram after a sacrificial layer is deposited on a first electrode and a first substrate according to an embodiment of the present application.

FIG. 12 is a schematic diagram of the sacrificial layer after being patterned according to an embodiment of the present application.

FIG. 13 is a schematic diagram of a vibrating film formed on a sacrificial layer according to an embodiment of the present application.

FIG. 14 is a schematic diagram of a second electrode formed on a vibrating film according to an embodiment of the present application.

FIG. 15 is a schematic diagram of the first substrate after patterning according to an embodiment of the present application.

FIG. 16 is a schematic diagram of etching the sacrificial layer using an etching solution according to an embodiment of the present application.

FIG. 17 is a schematic diagram before a light source is arranged on a second substrate according to an embodiment of the present application.

FIG. 18 is a schematic diagram of a light source disposed on a second substrate according to an embodiment of the present application.

Detailed ways

The following will be combined with Figures 1 to 18 in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application.

Please refer to Figure 1, which is a schematic diagram of the structure of an optical microphone provided in an embodiment of the present application. The embodiment of the present application provides an optical microphone 100, including a microphone diaphragm 200 and a photoelectric conversion component 300, wherein the microphone diaphragm 200 includes a vibration film 40 and a grating 225 arranged at intervals, and a sound inlet hole 41 is provided on the vibration film 40; the photoelectric conversion component 300 is arranged on a side of the grating 225 away from the vibration film 40, and the photoelectric conversion component 300 includes a light source 320 and a detector 330, wherein the light source 320 is used to emit light toward the microphone diaphragm 200, and the detector 330 is used to receive light reflected from the microphone diaphragm 200 and convert the light signal into an electrical signal.

When the optical microphone 100 provided in the embodiment of the present application is in use, sound waves enter through the sound inlet hole 41 of the vibrating film 40 and cause the vibrating film 40 to vibrate, thereby changing the distance between the vibrating film 40 and the grating 225. A portion of the light emitted by the light source 320 is diffracted by the grating 225 and irradiates the surface of the vibrating film 40 and is reflected back to the detector 330 by the vibrating film 40, and a portion of the light is directly reflected back to the detector 330 by the surface of the grating 225. When these two portions of light arrive at the detector 330, they have a certain optical path difference and phase difference. The optical path difference and phase difference are different from the distance between the vibrating film 40 and the grating 225. The optical microphone 100 of the embodiment of the present application has a sensitivity greater than 100 mV/Pa, which is far higher than the sensitivity of a conventional microphone. In addition, the optical microphone 100 is small in size and easy to carry.

Referring to FIG. 1 and FIG. 2 , a first reflection layer 61 is provided on the side of the grating 225 away from the vibration film 40, and a second reflection layer 62 is provided on the side of the vibration film 40 facing the grating 225. It can be understood that by providing the first reflection layer 61 on the side of the grating 225 away from the vibration film 40 and the second reflection layer 62 on the side of the vibration film 40 facing the grating 225, the reflectivity of the surface of the vibration film 40 and the surface of the grating 225 to light can be increased respectively, thereby enhancing the intensity of the light signal received by the detector 330, which is conducive to improving the sensitivity of the detector 330 when detecting changes in the light signal, thereby improving the sensitivity of the optical microphone 100.

Exemplarily, the material of the first reflective layer 61 and the material of the second reflective layer 62 are both metals, such as gold (Au). Exemplarily, the thickness of the first reflective layer 61 and the thickness of the second reflective layer 62 can both be 30 nanometers to 80 nanometers, such as 30 nanometers, 40 nanometers, 50 nanometers, 60 nanometers, 70 nanometers, 80 nanometers, etc.

Please refer to Figures 1 and 2. The microphone diaphragm 200 includes a first substrate 10, a first inorganic layer 20, a support member 30 and a vibration film 40 which are stacked in sequence. The first inorganic layer 20 is arranged on the first substrate 10, the support member 30 is arranged between the first inorganic layer 20 and the vibration film 40, the first inorganic layer 20 includes a grating 225, and the support member 30 is arranged corresponding to the periphery of the grating 225.

It can be understood that the support member 30 plays a role in supporting and fixing the vibration film 40. For example, the support member 30 may be ring-shaped.

1 and 2 , the first inorganic layer 20 includes a first silicon oxide layer 21 and a first silicon nitride layer 22 sequentially stacked on a first substrate 10 , a grating 225 is located on the first silicon nitride layer 22 , and a hollow 215 is formed on the first silicon oxide layer 21 corresponding to the position of the grating 225 . Exemplarily, the material of the first substrate 10 includes silicon, and the first silicon oxide layer 21 can be obtained by performing thermal oxidation treatment on the surface of the first substrate 10. It can be understood that since the first silicon oxide layer 21 is directly grown on the first substrate 10, the first silicon oxide layer 21 has a strong adhesion to the first substrate 10. In addition, since the adhesion between the first silicon oxide layer 21 and the first silicon nitride layer 22 is greater than the adhesion between the first silicon nitride layer 22 and the first substrate 10 (silicon), that is to say, the embodiment of the present application can improve the adhesion between the first silicon nitride layer 22 and the first substrate 10 by arranging the first silicon oxide layer 21 between the first substrate 10 and the first silicon nitride layer 22; in addition, the embodiment of the present application selects silicon nitride as the material of the grating 225. Since silicon nitride has good rigidity, the strength of the grating 225 can be improved.

Referring to FIG. 1 and FIG. 2 , a bending portion 42 bent toward the first inorganic layer 20 is provided on the vibration film 40, and the orthographic projection of the bending portion 42 on the first substrate 10 is located between the orthographic projection of the support member 30 on the first substrate 10 and the orthographic projection of the grating 225 on the first substrate 10. It can be understood that by providing the bending portion 42 bent toward the first inorganic layer 20 on the vibration film 40, the elasticity and flexibility of the vibration film 40 can be improved, and when the vibration film 40 vibrates under the action of sound waves, the vibration film 40 can be prevented from breaking during the vibration process, thereby improving the service life of the vibration film 40.

Referring to FIG. 1 and FIG. 2 , a first electrode layer 51 is provided on a side of the first inorganic layer 20 away from the first substrate 10, and a second electrode layer 52 is provided on a side of the vibration film 40 away from the first inorganic layer 20. It should be noted that, in the embodiment of the present application, by providing the first electrode layer 51 on a side of the first inorganic layer 20 away from the first substrate 10 and providing the second electrode layer 52 on a side of the vibration film 40 away from the first inorganic layer 20, a voltage difference can be formed between the first electrode layer 51 and the second electrode layer 52 by applying a voltage to the first electrode layer 51 and/or the second electrode layer 52, and the first electrode layer 51 and the second electrode layer 52 can be moved closer to or away from each other under the action of the voltage difference, thereby adjusting the distance between the first electrode layer 51 and the second electrode layer 52, and thus adjusting the distance between the vibration film 40 and the grating 225. By adjusting the distance between the vibration film 40 and the grating 225, the sensitivity of the optical microphone 100 can be adjusted, so that the optical microphone 100 achieves the best sensitivity.

For example, in the first inorganic layer 20, the thickness of the first silicon oxide layer 21 may be 100 nm to 900 nm, for example, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, The thickness of silicon nitride can be 650 nanometers to 950 nanometers, for example, 650 nanometers, 700 nanometers, 750 nanometers, 800 nanometers, 850 nanometers, 900 nanometers, 950 nanometers, etc.

Exemplarily, the thickness of the support member 30 may be 2 micrometers to 8 micrometers, such as 2 micrometers, 4 micrometers, 6 micrometers, 8 micrometers, etc.

Exemplarily, the thickness of the vibration film 40 may be 600 nanometers to 1000 nanometers, such as 600 nanometers, 700 nanometers, 800 nanometers, 900 nanometers, 1000 nanometers, etc.

Exemplarily, the material of the first electrode layer 51 and the material of the second electrode layer 52 both include polysilicon, such as low temperature polysilicon (LTPS). Exemplarily, the polysilicon may also be doped with N-type impurities (such as phosphorus) or P-type impurities (such as boron).

Exemplarily, the thickness of the first electrode layer 51 may be in the range of 100 nanometers to 500 nanometers, for example, 100 nanometers, 200 nanometers, 300 nanometers, 400 nanometers, 500 nanometers, etc.

Exemplarily, the thickness of the second electrode layer 52 may be 1 micrometer to 3 micrometers, such as 1 micrometer, 2 micrometers, 3 micrometers, etc.

For example, the material of the vibration film 40 may include silicon nitride. Since silicon nitride has good rigidity, the strength of the vibration film 40 is improved.

Referring to FIG. 1 and FIG. 3 , a sound inlet hole 41 is provided on the vibrating film 40, and the sound inlet hole 41 penetrates the vibrating film 40. The orthographic projection of the sound inlet hole 41 on the first substrate 10 is located between the orthographic projection of the support member 30 on the first substrate 10 and the orthographic projection of the grating 225 on the first substrate 10. It should be noted that by providing the sound inlet hole 41 on the vibrating film 40, sound waves can enter the gap between the vibrating film 40 and the grating 225 from the sound inlet hole 41, thereby causing the vibration of the vibrating film 40. As shown in FIG. 3 , the sound inlet hole 41 can be circular.

Please refer to FIG. 1 , FIG. 2 and FIG. 4 , the first inorganic layer 20 is provided with a vent hole 23, the vent hole 23 penetrates the first inorganic layer 20, and the orthographic projection of the vent hole 23 on the first substrate 10 is located between the orthographic projection of the support member 30 on the first substrate 10 and the orthographic projection of the grating 225 on the first substrate 10; it should be noted that by providing the vent hole 23 on the first inorganic layer 20, it is more conducive to the transmission of sound waves into the optical microphone 100, improving the vibration effect of the vibration film 40, and thus improving the sensitivity of the optical microphone 100. It can be understood that, since the area of the vent hole 23 is related to the transmission effect of the sound wave, the best sound wave transmission effect can be obtained by adjusting the area of the vent hole 23, thereby improving the vibration effect of the vibration film 40.

4 , the first inorganic layer 20 may include a grating 225, a first enclosure 25 surrounding the grating 225, a second enclosure 26 disposed outside the second enclosure 26, and a plurality of support arms 24 connecting the first enclosure 25 and the second enclosure 26, wherein the plurality of support arms 24 define a plurality of air holes 23 between the first enclosure 25 and the second enclosure 26. The grating 225 is composed of a first silicon nitride layer 22 , and the first surrounding frame 25 , the second surrounding frame 26 and the plurality of support arms 24 are all composed of a first silicon oxide layer 21 and a first silicon nitride layer 22 which are stacked.

It should be noted that, in the embodiments of the present application, the plurality may be two or more, for example, three, four, five, six, seven, eight, etc.

4 , the overall shape of the grating 225 may be circular, and the diameter of the grating 225 may be 100 microns to 900 microns, for example, 100 microns, 200 microns, 300 microns, 400 microns, 500 microns, 600 microns, 700 microns, 800 microns, 900 microns, etc.

Exemplarily, the grating 225 includes a plurality of grating plates arranged at intervals, the width of each grating plate is 1 micron to 3 microns (for example, 1 micron, 2 microns, 3 microns, etc.), the width of the interval between any two grating plates is 1 micron to 3 microns (for example, 1 micron, 2 microns, 3 microns, etc.), and the period of the grating 225 (the sum of the width of one grating plate and the width of one interval) is 2 microns to 6 microns (for example, 2 microns, 3 microns, 4 microns, 5 microns, 6 microns, etc.).

3 , the overall shape of the vibration film 40 may be circular, and the diameter of the vibration film 40 may be 100 mm to 900 mm, for example, 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, etc.

Please refer to FIG. 5 and FIG. 6 , the photoelectric conversion component 300 further includes a second substrate 310 , and the light source 320 and the detector 330 are both disposed on the second substrate 310 .

Exemplarily, the material of the second substrate 310 includes silicon.

By way of example, the detector 330 may include a photodiode.

Exemplarily, the light source 320 may be a vertical cavity surface emitting laser (VCSEL).

Exemplarily, the overall shape of the light source 320 can be circular or rectangular (rectangular or square), and the diameter of the circle and the length or width of the rectangle can each be 100 microns to 900 microns, for example, 100 microns, 200 microns, 300 microns, 400 microns, 500 microns, 600 microns, 700 microns, 800 microns, 900 microns, etc.

Exemplarily, the overall shape of the detector 330 can be circular or rectangular (rectangular or square), and the diameter of the circle and the length or width of the rectangle can each be 100 microns to 900 microns, for example, 100 microns, 200 microns, 300 microns, 400 microns, 500 microns, 600 microns, 700 microns, 800 microns, 900 microns, etc.

Referring to FIG. 5 and FIG. 6 , the second substrate 310 is further provided with a first connector 321, a second connector 322, a driving circuit 323 and a first grounding electrode 324. The driving circuit 323 is electrically connected to the second connector 322, and the first grounding electrode 324 is electrically connected to the first connector 321. The light source 320 has a first electrode and a second electrode. The first electrode of the light source 320 is connected to the first connector 321, and the second electrode of the light source 320 is connected to the second connector 322 via a wire 325. It is understood that the driving circuit 323 is used to apply a driving voltage to the light source 320 , thereby driving the light source 320 to emit light toward the grating 225 .

Please refer to Figures 5 and 6. A plurality of detectors 330 are provided on the second substrate 310. A plurality of filter circuits 331, a plurality of amplifier circuits 332, a differential circuit 333 and a second ground electrode 334 are also provided on the second substrate 310. The plurality of detectors 330 are respectively connected to the plurality of filter circuits 331, the plurality of filter circuits 331 are respectively connected to the plurality of amplifier circuits 332, the plurality of amplifier circuits 332 are all connected to the differential circuit 333, and the plurality of detectors 330 are all connected to the second ground electrode 334.

Exemplarily, the intensity of the optical signals received by the multiple detectors 330 is different. It should be noted that after the detector 330 converts the received optical signal into an electrical signal, the filter circuit 331 can filter out the interference signal in the electrical signal to reduce the noise, and the amplifier circuit 332 can amplify the intensity of the electrical signal to improve the detection sensitivity. The electrical signals output by the multiple detectors 330 are connected to the differential circuit 333 after filtering out the noise and amplifying. The differential circuit 333 performs two-by-two subtraction on the electrical signals of the multiple detectors 330, thereby further filtering out the interference signal. Specifically, the working principle of the differential circuit 333 is: if the electrical signals of the multiple detectors 330 are all interfered by the noise signal, then the interference degree of the noise signal on the electrical signals of the multiple detectors 330 is basically the same, then, by subtracting the electrical signals of the two detectors 330 and taking the difference of the two electrical signals as the effective input signal, the input of the noise signal can be basically reduced to zero, thereby achieving the purpose of anti-interference.

Exemplarily, the driving circuit 323 , the filtering circuit 331 , the amplifying circuit 332 , and the differential circuit 333 may be formed by implanting N-type ions or P-type ions on the second substrate 310 .

Exemplarily, the first ground electrode 324 and the second ground electrode 334 may be formed by electroplating, and the material of the first ground electrode 324 and the material of the second ground electrode 334 may both be metal, such as copper.

Exemplarily, the material of the first connection member 321 and the material of the second connection member 322 may both be metal, such as tin.

1, the outgoing light of the light source 320 is not perpendicular to the surface of the grating 225 on the side away from the vibration film 40. It is understandable that when the outgoing light of the light source 320 is perpendicular to the surface of the grating 225 on the side away from the vibration film 40, the outgoing light of the light source 320 will be directly reflected back to the light source 320 by the grating 225, thereby causing the light source 320 to be burned.

5, the angle between the light emitting surface of the light source 320 and the second substrate 310 is an acute angle, and the light emitted by the light source 320 is perpendicular to the light emitting surface of the light source 320. Exemplarily, the first substrate 10 and the second substrate 310 are parallel to each other. In some embodiments, the angle between the light emitting surface of the light source 320 and the second substrate 310 is 6° to 8°, for example, 6°, 7°, 8°, etc.

1 , the optical microphone 100 further includes a carrier 400, a second substrate 310 of the photoelectric conversion component 300 and The first substrate 10 of the microphone diaphragm 200 is connected to the carrier 400, and the first substrate 10 of the microphone diaphragm 200 is connected to the carrier 400 through an adhesive 500, and the adhesive 500 is arranged corresponding to the periphery of the photoelectric conversion component 300. It can be seen that the photoelectric conversion component 300 is enclosed in a space surrounded by the microphone diaphragm 200, the adhesive 500 and the carrier 400, so that the photoelectric conversion component 300 can be prevented from being invaded by external water and oxygen, thereby extending the service life of the photoelectric conversion component 300. Exemplarily, the adhesive 500 may include epoxy resin. Exemplarily, the carrier 400 is in the shape of a plate, and the material of the carrier 400 may be metal, such as copper.

Exemplarily, the distance between the vibration film 40 and the grating 225 may be 0.5 mm to 3 mm, such as 0.5 mm, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, etc.

Please refer to FIG. 7 , which is a flow chart of a method for manufacturing an optical microphone provided in an embodiment of the present application. The present application also provides a method for manufacturing an optical microphone, which can be used to manufacture the optical microphone 100 in any of the above embodiments. The manufacturing method may include:

S100, providing a microphone diaphragm and a photoelectric conversion component, the microphone diaphragm includes a vibration film and a grating arranged at intervals, and the vibration film is provided with a sound inlet hole; the photoelectric conversion component includes a light source and a detector, the light source is used to emit light toward the microphone diaphragm, and the detector is used to receive light reflected from the microphone diaphragm and convert the optical signal into an electrical signal.

S200, connecting the microphone diaphragm and the photoelectric conversion component, so that the photoelectric conversion component is arranged on the side of the grating away from the vibration film, to obtain an optical microphone.

Please refer to FIG. 8 to FIG. 16 , “providing a microphone diaphragm 200 ” may specifically include:

Referring to FIG. 8 , a first substrate 10 is provided, and a first inorganic layer 20 is formed on the first substrate 10 . Referring to FIG. 9 , the first inorganic layer 20 is patterned to form a grating pattern 201 .

Please refer to FIG. 10 , a first electrode layer 51 is formed on the first inorganic layer 20 ;

Referring to FIG. 11 , a sacrificial layer 31 is deposited on the first electrode layer 51 and the first substrate 10. Referring to FIG. 12 , the sacrificial layer 31 is patterned to form a filling portion 311, a supporting portion 312, and a groove 313 between the supporting portion 312 and the filling portion 311 on the sacrificial layer 31. The filling portion 311 is arranged corresponding to the grating pattern 201, the supporting portion 312 is arranged at the periphery of the filling portion 311, and the groove 313 penetrates the sacrificial layer 31 and separates the supporting portion 312 from the filling portion 311.

Please refer to FIG. 13 , a vibration film 40 is formed on the sacrificial layer 31 ;

Please refer to FIG. 14 , a second electrode layer 52 is formed on the vibration film 40 ;

Please refer to FIG. 15 , the first substrate 10 is patterned to form a first notch 27 corresponding to the grating pattern 201 on the first substrate 10 ;

16, the sacrificial layer 31 is etched by an etching solution, and the etching solution corrodes the filling portion 311 through the first notch 27, removes the filling portion 311, and forms a gap between the vibration film 40 and the grating pattern 201; The support portion 312 is not etched, and forms the support member 30 for supporting the vibration film 40 .

Illustratively, the material of the first electrode layer 51 and the material of the second electrode layer 52 can both be polysilicon. In some embodiments, the first electrode layer 51 and the second electrode layer 52 can be prepared by low pressure chemical vapor deposition (LPCVD).

Please refer to FIG. 2 . After the sacrificial layer 31 is etched with an etching solution, “providing a microphone diaphragm 200 ” may further include: forming a first reflection layer 61 on the side of the grating 225 away from the vibration film 40 and forming a second reflection layer 62 on the side of the vibration film 40 facing the grating 225 by evaporation (e.g., electron beam evaporation) to improve the reflectivity of the surface of the grating 225 and the surface of the vibration film 40. Exemplarily, the material of the first reflection layer 61 and the material of the second reflection layer 62 are both metals, such as gold (Au). It can be understood that, during the evaporation process, the metal material is dispersed in a gaseous state to the surface of the grating 225 to form the first reflection layer 61, and the gaseous metal material can pass through the gap of the grating 225 and then reach the surface of the vibration film 40 to form the second reflection layer 62. That is to say, the first reflection layer 61 and the second reflection layer 62 can be formed in the same evaporation process.

8 and 9 , the material of the first substrate 10 includes silicon, and the first inorganic layer 20 includes a first silicon oxide layer 21 and a first silicon nitride layer 22 which are sequentially stacked on the first substrate 10 .

Exemplarily, “forming a first inorganic layer 20 on a first substrate 10” may specifically include:

The surface of the first substrate 10 is oxidized to obtain a first silicon oxide layer 21;

The first silicon nitride layer 22 is formed on the first silicon oxide layer 21 by chemical vapor deposition.

By way of example, a thermal oxidation process may be performed on the surface of the first substrate 10 to obtain the first silicon oxide layer 21 .

For example, a first silicon nitride layer 22 can be formed on the first silicon oxide layer 21 by low pressure chemical vapor deposition (LPCVD).

Exemplarily, the material of the sacrificial layer 31 is silicon oxide; while the filling portion 311 of the sacrificial layer 31 is etched through the first notch 27 by an etching solution, the first silicon oxide layer 21 on the surface of the grating pattern 201 is etched away. It is understandable that, since the material (silicon oxide) of the sacrificial layer 31 is the same as that of the first silicon oxide layer 21, the sacrificial layer 31 and the first silicon oxide layer 21 can be etched by the same etching solution.

For example, the first silicon oxide layer 21 on the surface of the grating pattern 201 may be removed by chemical mechanical polishing (CMP), thereby forming a hollow 215 corresponding to the grating 225 on the first silicon oxide layer 21. It is understood that CMP is a technology that combines chemical action and mechanical action, that is, the first silicon oxide layer 21 on the surface of the grating pattern 201 is removed by a combination of etching liquid etching and mechanical polishing.

11, after the sacrificial layer 31 is deposited on the first electrode layer 51 and the first substrate 10, the sacrificial layer 31 is A groove 314 should be formed at the position of the air hole 23, the groove 314 does not penetrate the filling portion 311, and the groove 314 is arranged corresponding to the periphery of the grating 225;

Referring to FIG. 13 , when the vibration film 40 is formed on the sacrificial layer 31 , the vibration film 40 forms a bent portion 42 at the groove 314 .

Please refer to Figures 9 to 11. Since there is a depression at the position of the air hole 23 on the first inorganic layer 20, during the deposition of the sacrificial layer 31, the deposition material needs to first fill the air hole 23, resulting in a lower thickness at the position corresponding to the air hole 23 on the sacrificial layer 31, thereby forming a groove 314 relative to the surrounding area.

8 and 9 , after the first inorganic layer 20 is patterned, while forming the grating 225, a vent hole 23 may be formed on the first inorganic layer 20, the vent hole 23 penetrates the first inorganic layer 20, and the vent hole 23 is disposed at the periphery of the grating 225;

15 , after the first substrate 10 is patterned, a first notch 27 corresponding to the grating pattern 201 is formed on the first substrate 10 , and a second notch 28 corresponding to the air hole 23 is formed on the first substrate 10 ;

16 , when the sacrificial layer 31 is etched with an etching solution, while the etching solution corrodes the filling portion 311 through the first notch 27 , the etching solution also corrodes the portion of the filling portion 311 located within the vent hole 23 through the second notch 28 .

Please combine Figure 13 with Figure 3. After the vibration film 40 is formed on the sacrificial layer 31, the vibration film 40 is patterned to form a sound inlet hole 41. The sound inlet hole 41 penetrates the vibration film 40. The orthographic projection of the sound inlet hole 41 on the first substrate 10 is located between the orthographic projection of the support member 30 on the first substrate 10 and the orthographic projection of the grating 225 on the first substrate 10.

Referring to FIG. 5 , “providing a photoelectric conversion component 300 ” may specifically include: providing a second substrate 310 , forming a detector 330 on the second substrate 310 , and arranging a light source 320 on the second substrate 310 .

5 , the material of the second substrate 310 includes silicon, and the detector 330 includes a photodiode;

“Forming the detector 330 on the second substrate 310 ” may specifically include: injecting P-type ions and N-type ions into the second substrate 310 to form a PN junction, and the PN junction forms a photodiode.

Please refer to FIG. 6 , “providing a photoelectric conversion component 300 ” may further include:

A first connection member 321, a second connection member 322, a driving circuit 323 and a first ground electrode 324 are formed on the second substrate 310, the driving circuit 323 is electrically connected to the second connection member 322, and the first ground electrode 324 is electrically connected to the first connection member 321;

Referring to FIGS. 17 and 18 , “arranging a light source 320 on the second substrate 310 ” may specifically include: providing a light source 320 , wherein the light source 320 has a first electrode and a second electrode, connecting the first electrode of the light source 320 to a first connecting member 321 , Furthermore, a wire 325 is used to connect the second electrode of the light source 320 and the second connecting member 322 .

Exemplarily, the first electrode layer 51 of the light source 320 may be connected to the first connecting member 321 by welding or bonding.

For example, the driving circuit 323 may be formed on the second substrate 310 by implanting P-type ions or N-type ions into the second substrate 310 .

By way of example, the first connection member 321 , the second connection member 322 , and the first ground electrode 324 may be formed on the second substrate 310 by electroplating.

Exemplarily, the material of the wire 325 may be metal, such as aluminum (Al).

Please refer to Figure 6. A plurality of detectors 330 are provided on the second substrate 310. “Providing a photoelectric conversion component 300” may specifically include: forming a plurality of filter circuits 331, a plurality of amplifier circuits 332, a differential circuit 333 and a second ground electrode 334 on the second substrate 310; the plurality of detectors 330 are respectively connected to the plurality of filter circuits 331, the plurality of filter circuits 331 are respectively connected to the plurality of amplifier circuits 332, the plurality of amplifier circuits 332 are all connected to the differential circuit 333, and the plurality of detectors 330 are all connected to the second ground electrode 334.

For example, the filter circuit 331 , the amplifier circuit 332 , and the differential circuit 333 may be formed on the second substrate 310 by implanting P-type ions or N-type ions into the second substrate 310 .

By way of example, the second ground electrode 334 may be formed on the second substrate 310 by electroplating.

Referring to FIG. 1 , “connecting the microphone diaphragm 200 and the photoelectric conversion component 300 ” may specifically include:

Providing a carrier 400, fixing the second substrate 310 of the photoelectric conversion component 300 on the carrier 400;

The first substrate 10 of the microphone diaphragm 200 is fixed on the carrier 400 by means of adhesive 500 , and the adhesive 500 is arranged corresponding to the periphery of the photoelectric conversion component 300 .

The optical microphone and its manufacturing method provided in the embodiment of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application. At the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

An optical microphone, comprising:

A microphone diaphragm, the microphone diaphragm comprising a vibrating film and a grating arranged at intervals, and a sound inlet hole is provided on the vibrating film;

The photoelectric conversion component is arranged on the side of the grating away from the vibration film, and the photoelectric conversion component includes a light source and a detector. The light source is used to emit light toward the microphone diaphragm, and the detector is used to receive the light reflected from the microphone diaphragm and convert the optical signal into an electrical signal.
The optical microphone according to claim 1, wherein a first reflection layer is provided on a side of the grating facing away from the vibration film, and a second reflection layer is provided on a side of the vibration film facing the grating.
The optical microphone according to claim 1, wherein the microphone diaphragm includes a first substrate, a first inorganic layer, a support member and a vibration film which are stacked in sequence, the first inorganic layer is arranged on the first substrate, the support member is arranged between the first inorganic layer and the vibration film, the first inorganic layer includes the grating, and the support member is arranged corresponding to the periphery of the grating.
The optical microphone according to claim 3, wherein the first inorganic layer comprises a first silicon oxide layer and a first silicon nitride layer stacked in sequence on the first substrate, the grating is located on the first silicon nitride layer, and a hollow is formed on the first silicon oxide layer at a position corresponding to the grating.
The optical microphone according to claim 3, wherein the vibration film is provided with a bent portion bent toward the first inorganic layer, and the orthographic projection of the bent portion on the first substrate is located between the orthographic projection of the support member on the first substrate and the orthographic projection of the grating on the first substrate.
The optical microphone according to claim 3, wherein a first electrode layer is provided on a side of the first inorganic layer facing away from the first substrate, and a second electrode layer is provided on a side of the vibration film facing away from the first inorganic layer.
The optical microphone according to claim 6, wherein the material of the first electrode layer and the material of the second electrode layer both include polysilicon, and the material of the vibration film includes silicon nitride.
The optical microphone according to claim 3, wherein the vibration film is provided with a sound inlet hole, the sound inlet hole penetrates the vibration film, and the orthographic projection of the sound inlet hole on the first substrate is located between the orthographic projection of the support member on the first substrate and the orthographic projection of the grating on the first substrate;

The first inorganic layer is provided with air holes, the air holes penetrate the first inorganic layer, and the orthographic projection of the air holes on the first substrate is located between the orthographic projection of the support member on the first substrate and the orthographic projection of the grating on the first substrate.
The optical microphone according to claim 1, wherein the photoelectric conversion component further comprises a second substrate. The light source and the detector are both disposed on the second substrate;

The second substrate is also provided with a first connection member, a second connection member, a driving circuit and a first grounding electrode, the driving circuit is electrically connected to the second connection member, and the first grounding electrode is electrically connected to the first connection member;

The light source has a first electrode and a second electrode; the first electrode of the light source is connected to the first connecting member, and the second electrode of the light source is connected to the second connecting member through a wire.
The optical microphone according to claim 9, wherein a plurality of the detectors are provided on the second substrate, and a plurality of filter circuits, a plurality of amplifier circuits, a differential circuit and a second ground electrode are also provided on the second substrate; the plurality of the detectors are respectively connected to a plurality of the filter circuits, the plurality of the filter circuits are respectively connected to a plurality of the amplifier circuits, the plurality of the amplifier circuits are all connected to the differential circuit, and the plurality of the detectors are all connected to the second ground electrode.
The optical microphone according to claim 1, wherein the outgoing light of the light source is in a non-perpendicular relationship with the surface of the grating facing away from the vibration film.
The optical microphone according to claim 1, wherein the optical microphone further comprises a carrier, the photoelectric conversion component is connected to the carrier, and the microphone diaphragm is connected to the carrier via an adhesive, and the adhesive is arranged corresponding to the periphery of the photoelectric conversion component.
A method for manufacturing an optical microphone, comprising:

A microphone diaphragm and a photoelectric conversion component are provided, wherein the microphone diaphragm includes a vibration film and a grating arranged at intervals, and a sound inlet hole is provided on the vibration film; the photoelectric conversion component includes a light source and a detector, wherein the light source is used to emit light toward the microphone diaphragm, and the detector is used to receive light reflected from the microphone diaphragm and convert the light signal into an electrical signal;

The microphone diaphragm and the photoelectric conversion component are connected so that the photoelectric conversion component is arranged on a side of the grating away from the vibration film to obtain an optical microphone.
The method for manufacturing an optical microphone according to claim 13, wherein providing a microphone diaphragm comprises:

Providing a first substrate, forming a first inorganic layer on the first substrate, and performing patterning on the first inorganic layer to form a grating pattern;

forming a first electrode layer on the first inorganic layer;

Depositing a sacrificial layer on the first electrode layer and the first substrate, and patterning the sacrificial layer to form a filling portion, a supporting portion, and a groove between the supporting portion and the filling portion on the sacrificial layer, wherein the filling portion is arranged corresponding to the grating pattern, the supporting portion is arranged at the periphery of the filling portion, and the groove penetrates the sacrificial layer and separates the supporting portion from the filling portion;

forming a vibration film on the sacrificial layer;

forming a second electrode layer on the vibration film;

Performing a patterning process on the first substrate to form a first notch corresponding to the grating pattern on the first substrate;

The sacrificial layer is etched by an etching liquid, and the etching liquid corrodes the filling part through the first notch to remove the filling part, thereby forming a gap between the vibration film and the grating pattern; the supporting part of the sacrificial layer is not etched, thereby forming a supporting member for supporting the vibration film.
The method for manufacturing an optical microphone according to claim 14, wherein the material of the first substrate comprises silicon, and the first inorganic layer comprises a first silicon oxide layer and a first silicon nitride layer sequentially stacked on the first substrate;

The forming of a first inorganic layer on the first substrate comprises:

performing oxidation treatment on the surface of the first substrate to obtain a first silicon oxide layer;

A first silicon nitride layer is formed on the first silicon oxide layer by chemical vapor deposition.
According to the method for manufacturing an optical microphone according to claim 15, the material of the sacrificial layer is silicon oxide; while etching the filling portion of the sacrificial layer through the first notch using an etching solution, the first silicon oxide layer on the surface of the grating pattern is etched away to obtain a grating.
The method for manufacturing an optical microphone according to claim 14, wherein, after the first inorganic layer is patterned, while forming the grating, an air hole is formed on the first inorganic layer, the air hole penetrates the first inorganic layer, and the air hole is arranged at the periphery of the grating;

After patterning the first substrate, a first notch corresponding to the grating pattern is formed on the first substrate, and a second notch corresponding to the air hole is formed on the first substrate;

When the sacrificial layer is etched by an etching liquid, while the etching liquid corrodes the filling portion through the first notch, the etching liquid also corrodes the portion of the filling portion located in the air hole through the second notch.
The method for manufacturing an optical microphone according to claim 17, wherein after depositing a sacrificial layer on the first electrode and the first substrate, a groove is formed on the sacrificial layer at a position corresponding to the air hole;

When a vibration film is formed on the sacrificial layer, a bending portion is formed on the vibration film at the groove.
According to the manufacturing method of the optical microphone according to claim 14, after the vibration film is formed on the sacrificial layer, the vibration film is patterned to form a sound inlet hole, the sound inlet hole penetrates the vibration film, and the orthographic projection of the sound inlet hole on the first substrate is located between the orthographic projection of the support member on the first substrate and the orthographic projection of the grating on the first substrate.
The method for manufacturing an optical microphone according to claim 14, wherein the sacrificial After the layer is etched, the providing of the microphone diaphragm further comprises: forming a first reflection layer on a side of the grating away from the vibration film and forming a second reflection layer on a side of the vibration film facing the grating by using an evaporation method.
According to the method for manufacturing an optical microphone according to claim 13, wherein providing a photoelectric conversion component comprises: providing a second substrate, forming a detector on the second substrate, and arranging a light source on the second substrate.
The method for manufacturing an optical microphone according to claim 21, wherein the material of the second substrate comprises silicon, and the detector comprises a photodiode;

The forming of the detector on the second substrate includes: implanting P-type ions and N-type ions into the second substrate to form a PN junction, and the PN junction constitutes the photodiode.
The method for manufacturing an optical microphone according to claim 21, wherein providing a photoelectric conversion component further comprises: forming a first connector, a second connector, a drive circuit and a first ground electrode on the second substrate, wherein the drive circuit is electrically connected to the second connector, and the first ground electrode is electrically connected to the first connector;

The step of arranging a light source on the second substrate comprises:

A light source is provided, wherein the light source has a first electrode and a second electrode; the first electrode of the light source is connected to the first connecting member, and the second electrode of the light source is connected to the second connecting member by a wire.
According to the manufacturing method of the optical microphone according to claim 21, a plurality of the detectors are provided on the second substrate, and the providing of the photoelectric conversion component also includes: forming a plurality of filter circuits, a plurality of amplifier circuits, a differential circuit and a second ground electrode on the second substrate; the plurality of the detectors are respectively connected to the plurality of the filter circuits, the plurality of the filter circuits are respectively connected to the plurality of the amplifier circuits, the plurality of the amplifier circuits are all connected to the differential circuit, and the plurality of the detectors are all connected to the second ground electrode.
The method for manufacturing an optical microphone according to claim 13, wherein the step of connecting the microphone diaphragm and the photoelectric conversion component comprises:

Providing a carrier, and fixing the photoelectric conversion component on the carrier;

The microphone diaphragm is fixed on the carrier by adhesive, and the adhesive is arranged corresponding to the periphery of the photoelectric conversion component.