Optical microphone and method of manufacturing the same
By converting sound signals into light signals and then into electrical signals using an optical microphone, and using the distance changes of the grating and the vibrating diaphragm to calculate the changes in sound signals, the problem of low sensitivity of traditional microphones is solved, achieving high sensitivity and miniaturization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD
- Filing Date
- 2022-12-28
- Publication Date
- 2026-07-14
AI Technical Summary
Traditional microphones have low sensitivity and cannot meet consumers' increasingly demanding experience requirements.
An optical microphone design is used to convert sound signals into light signals, and then into electrical signals. Changes in the sound signal are calculated by the change in distance between the grating and the vibrating diaphragm, and the sensitivity is improved by combining photoelectric conversion components.
It achieves a sensitivity greater than 100mV/Pa, far exceeding that of traditional microphones, and is small in size, making it easy to carry.
Smart Images
Figure CN116074715B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electronic technology, and in particular to an optical microphone and a method for manufacturing the same. Background Technology
[0002] Microphones are a common sound signal acquisition tool in people's daily lives. With the gradual development of microphone technology, the application fields of microphones have continued to expand. They have begun to undertake a variety of new applications such as acoustic sensing, speech recognition, sonar detection, and ultrasonic non-destructive testing, and have played an indispensable role in people's livelihood, scientific research, medical care, industry, national defense and other fields.
[0003] Traditional microphones consist of a backplate and a diaphragm spaced apart from it. The diaphragm vibrates under the influence of sound waves, and voltage changes are generated by altering the distance between the backplate and the diaphragm, thus achieving sound-to-electricity conversion. However, this type of microphone suffers from low sensitivity, failing to meet the increasingly demanding experience requirements of consumers. Therefore, it is necessary to develop a new type of microphone with higher sensitivity. Summary of the Invention
[0004] This application provides an optical microphone and a method for manufacturing the same. The optical microphone can convert sound signals into light signals and then into electrical signals, thereby achieving sound-to-electric conversion. Furthermore, the sensitivity of the optical microphone is greater than 100mV / Pa, which is far greater than that of traditional microphones. In addition, the optical microphone is small in size and easy to carry.
[0005] In a first aspect, embodiments of this application provide an optical microphone, including:
[0006] A microphone diaphragm, comprising a spaced-apart vibrating diaphragm and a grating, wherein the vibrating diaphragm has a sound inlet hole;
[0007] A photoelectric conversion component is disposed on the side of the grating away from the vibrating diaphragm. 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 back from the microphone diaphragm and convert the light signal into an electrical signal.
[0008] Secondly, embodiments of this application provide a method for manufacturing an optical microphone, comprising:
[0009] A microphone diaphragm and a photoelectric conversion assembly are provided. The microphone diaphragm includes a spaced-apart vibrating film and a grating, and the vibrating film has a sound inlet hole. The photoelectric conversion assembly 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 back from the microphone diaphragm and convert the light signal into an electrical signal.
[0010] By connecting the microphone diaphragm and the photoelectric conversion component, and placing the photoelectric conversion component on the side of the grating away from the vibrating film, an optical microphone is obtained.
[0011] In use, the optical microphone provided in this application embodiment allows sound waves to enter through the sound inlet of the vibrating diaphragm, causing the diaphragm to vibrate. This changes the distance between the vibrating diaphragm and the grating. Part of the light emitted from the light source is diffracted by the grating and then reflects back to the detector. Another part is directly reflected back to the detector from the grating surface. These two parts of light have a certain optical path difference and phase difference when they reach the detector. This optical path difference and phase difference are related to the distance between the vibrating diaphragm and the grating. Therefore, the change in distance between the vibrating diaphragm and the grating can be calculated based on the optical path difference and phase difference of the light signal detected by the detector. Furthermore, the change in sound signal can be calculated based on the change in distance between the vibrating diaphragm and the grating, thus achieving the conversion between sound and light signals. In terms of performance, the optical microphone provided in this application embodiment has a sensitivity greater than 100mV / Pa, far exceeding the sensitivity of traditional microphones. Moreover, the optical microphone is small in size and easy to carry. Attached Figure Description
[0012] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below.
[0013] Figure 1 This is a schematic diagram of the structure of an optical microphone provided in an embodiment of this application.
[0014] Figure 2 This is a schematic diagram of the structure of a microphone diaphragm provided in an embodiment of this application.
[0015] Figure 3 This is a top view of the vibrating diaphragm provided in an embodiment of this application.
[0016] Figure 4 This is a bottom view of the first inorganic layer provided in an embodiment of this application.
[0017] Figure 5 This is a schematic diagram of a portion of the structure of the photoelectric conversion component provided in an embodiment of this application.
[0018] Figure 6 This is a top view schematic diagram of the photoelectric conversion component provided in the embodiments of this application.
[0019] Figure 7 A flowchart illustrating a method for manufacturing an optical microphone as provided in an embodiment of this application.
[0020] Figure 8This is a schematic diagram showing the formation of a first inorganic layer on a first substrate, as provided in an embodiment of this application.
[0021] Figure 9 This is a schematic diagram of the first inorganic layer after graphical processing, provided as an embodiment of this application.
[0022] Figure 10 This is a schematic diagram showing the formation of a first electrode on a first inorganic layer, as provided in an embodiment of this application.
[0023] Figure 11 This is a schematic diagram showing the deposition of a sacrificial layer on the first electrode and the first substrate, as provided in an embodiment of this application.
[0024] Figure 12 This is a schematic diagram showing the graphical processing of the sacrificial layer as provided in an embodiment of this application.
[0025] Figure 13 This is a schematic diagram showing the formation of a vibration film on the sacrificial layer, as provided in an embodiment of this application.
[0026] Figure 14 This is a schematic diagram showing the formation of a second electrode on a vibrating thin film, as provided in an embodiment of this application.
[0027] Figure 15 This is a schematic diagram of the first substrate after patterning, provided as an embodiment of this application.
[0028] Figure 16 This is a schematic diagram showing the effect of etching the sacrificial layer with an etchant, as provided in an embodiment of this application.
[0029] Figure 17 This is a schematic diagram of the second substrate before a light source is placed, as provided in an embodiment of this application.
[0030] Figure 18 This is a schematic diagram showing the arrangement of a light source on a second substrate, as provided in an embodiment of this application. Detailed Implementation
[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0032] Please see Figure 1 , Figure 1This is a schematic diagram of the structure of an optical microphone provided in an embodiment of this application. This application provides an optical microphone 100, including a microphone diaphragm 200 and a photoelectric conversion component 300. The microphone diaphragm 200 includes a vibrating thin film 40 and a grating 225 spaced apart, with a sound inlet 41 on the vibrating thin film 40. The photoelectric conversion component 300 is disposed on the side of the grating 225 away from the vibrating thin film 40, and includes a light source 320 and a detector 330. The light source 320 emits light toward the microphone diaphragm 200, and the detector 330 receives the light reflected back from the microphone diaphragm 200 and converts the optical signal into an electrical signal.
[0033] In use, the optical microphone 100 provided in this embodiment allows sound waves to enter through the sound inlet 41 of the vibrating diaphragm 40, causing the diaphragm 40 to vibrate. This changes the distance between the vibrating diaphragm 40 and the grating 225. A portion of the light emitted from the light source 320 is diffracted by the grating 225 and then illuminates the surface of the vibrating diaphragm 40, and is reflected back to the detector 330. Another portion is directly reflected back to the detector 330 by the surface of the grating 225. These two portions of light have a certain optical path difference and phase difference when they reach the detector 330. This optical path difference and phase difference are related to the distance between the vibrating diaphragm 40 and the grating 225. The distance between the gratings 225 is related to the optical path difference and phase difference of the optical signal detected by the detector 330. Therefore, the change range of the distance between the vibrating film 40 and the grating 225 can be calculated based on the relevant parameters such as the optical path difference and phase difference of the optical signal detected by the detector 330. Then, the change range of the sound signal can be calculated based on the change range of the distance between the vibrating film 40 and the grating 225, so as to realize the conversion between the sound signal and the optical signal. In terms of performance, the sensitivity of the optical microphone 100 provided in this embodiment is greater than 100mV / Pa, which is far greater than the sensitivity of traditional microphones. In addition, the optical microphone 100 is small in size and easy to carry.
[0034] Please see Figure 1 and Figure 2 A first reflective layer 61 is provided on the side of the grating 225 facing away from the vibrating film 40, and a second reflective layer 62 is provided on the side of the vibrating film 40 facing the grating 225. It can be understood that by providing the first reflective layer 61 on the side of the grating 225 facing away from the vibrating film 40 and the second reflective layer 62 on the side of the vibrating film 40 facing the grating 225, the reflectivity of the surfaces of the vibrating film 40 and the grating 225 to light can be increased respectively, thereby enhancing the intensity of the light signal received by the detector 330. This is beneficial for improving the sensitivity of the detector 330 when detecting changes in the light signal, and thus improving the sensitivity of the optical microphone 100.
[0035] For example, the materials of the first reflective layer 61 and the second reflective layer 62 are both metals, such as gold (Au). For example, 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.
[0036] Please see Figure 1 and Figure 2 The microphone diaphragm 200 includes a first substrate 10, a first inorganic layer 20, a support member 30, and a vibrating film 40, which are stacked in sequence. The first inorganic layer 20 is disposed on the first substrate 10, and the support member 30 is disposed between the first inorganic layer 20 and the vibrating film 40. The first inorganic layer 20 includes a grating 225, and the support member 30 is disposed around the periphery of the grating 225.
[0037] It is understood that the support member 30 serves to support and fix the vibrating diaphragm 40. For example, the support member 30 may be annular.
[0038] Please see Figure 1 and Figure 2 The first inorganic layer 20 includes a first silicon oxide layer 21 and a first silicon nitride layer 22 sequentially stacked on the first substrate 10. The grating 225 is located on the first silicon nitride layer 22, and a cutout 215 is formed on the first silicon oxide layer 21 corresponding to the position of the grating 225. For example, the material of the first substrate 10 includes silicon. The first silicon oxide layer 21 can be obtained by thermal oxidation treatment of the surface of the first substrate 10. It is understood that since the first silicon oxide layer 21 is directly grown on the first substrate 10, the first silicon oxide layer 21 and the first substrate 10 have a strong adhesion. 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, by providing the first silicon oxide layer 21 between the first substrate 10 and the first silicon nitride layer 22, the adhesion between the first silicon nitride layer 22 and the first substrate 10 can be improved. In addition, the present application embodiment 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.
[0039] Please see Figure 1 and Figure 2The vibrating diaphragm 40 has a bent portion 42 that bends toward the first inorganic layer 20. The orthographic projection of the bent 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 bent portion 42 that bends toward the first inorganic layer 20 on the vibrating diaphragm 40, the elasticity and flexibility of the vibrating diaphragm 40 can be improved. When the vibrating diaphragm 40 vibrates under the action of sound waves, it can prevent the vibrating diaphragm 40 from breaking during the vibration process, thereby improving the service life of the vibrating diaphragm 40.
[0040] Please see Figure 1 and Figure 2 A first electrode layer 51 is provided on the side of the first inorganic layer 20 facing away from the first substrate 10, and a second electrode layer 52 is provided on the side of the vibrating film 40 facing away from the first inorganic layer 20. It should be noted that, in this embodiment, by providing the first electrode layer 51 on the side of the first inorganic layer 20 facing away from the first substrate 10 and the second electrode layer 52 on the side of the vibrating film 40 facing 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 them. This allows the first electrode layer 51 and the second electrode layer 52 to move closer or further apart under the influence of the voltage difference, thereby adjusting the distance between the first electrode layer 51 and the second electrode layer 52. This, in turn, allows adjustment of the distance between the vibrating film 40 and the grating 225. By adjusting the distance between the vibrating film 40 and the grating 225, the sensitivity of the optical microphone 100 can be adjusted, allowing the optical microphone 100 to achieve optimal sensitivity.
[0041] For example, in the first inorganic layer 20, the thickness of the first silicon oxide layer 21 can be 100 nanometers to 900 nanometers, such as 100 nanometers, 200 nanometers, 300 nanometers, 400 nanometers, 500 nanometers, 600 nanometers, 700 nanometers, 800 nanometers, 900 nanometers, etc., and the thickness of the silicon nitride can be 650 nanometers to 950 nanometers, such as 650 nanometers, 700 nanometers, 750 nanometers, 800 nanometers, 850 nanometers, 900 nanometers, 950 nanometers, etc.
[0042] For example, the thickness of the support 30 can be 2 micrometers to 8 micrometers, such as 2 micrometers, 4 micrometers, 6 micrometers, 8 micrometers, etc.
[0043] For example, the thickness of the vibrating film 40 can be 600 nanometers to 1000 nanometers, such as 600 nanometers, 700 nanometers, 800 nanometers, 900 nanometers, 1000 nanometers, etc.
[0044] For example, the materials of the first electrode layer 51 and the second electrode layer 52 both include polycrystalline silicon, such as low-temperature polycrystalline silicon (LTPS). For example, the polycrystalline silicon may also be doped with N-type impurities (e.g., phosphorus) or P-type impurities (e.g., boron).
[0045] For example, the thickness of the first electrode layer 51 can be 100 nanometers to 500 nanometers, such as 100 nanometers, 200 nanometers, 300 nanometers, 400 nanometers, 500 nanometers, etc.
[0046] For example, the thickness of the second electrode layer 52 can be 1 micrometer to 3 micrometers, such as 1 micrometer, 2 micrometers, 3 micrometers, etc.
[0047] For example, the material of the vibrating diaphragm 40 may include silicon nitride, which has good rigidity, thus improving the strength of the vibrating diaphragm 40.
[0048] Please see Figure 1 and Figure 3 The vibrating diaphragm 40 has a sound inlet 41 that penetrates the diaphragm 40. The orthographic projection of the sound inlet 41 on the first substrate 10 lies between the orthographic projection of the support 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 41 on the vibrating diaphragm 40, sound waves can enter the gap between the vibrating diaphragm 40 and the grating 225 through the sound inlet 41, thereby causing the vibrating diaphragm 40 to vibrate. Figure 3 As shown, the sound inlet 41 can be circular.
[0049] Please see Figure 1 , Figure 2 and Figure 4 The first inorganic layer 20 has vent holes 23 that penetrate the first inorganic layer 20. The orthographic projection of the vent holes 23 on the first substrate 10 is located between the orthographic projection of the support 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 vent holes 23 on the first inorganic layer 20, it is more conducive to the transmission of sound waves into the optical microphone 100, thereby improving the vibration effect of the vibrating diaphragm 40 and thus improving the sensitivity of the optical microphone 100. It is understandable that since the area of the vent holes 23 is related to the sound wave transmission effect, the optimal sound wave transmission effect can be obtained by adjusting the area of the vent holes 23, thereby improving the vibration effect of the vibrating diaphragm 40.
[0050] Please combine Figure 4The first inorganic layer 20 may include a grating 225, a first frame 25 surrounding the grating 225, a second frame 26 disposed around the periphery of the second frame 26, and a plurality of support arms 24 connecting the first frame 25 and the second frame 26. The plurality of support arms 24 define a plurality of ventilation holes 23 between the first frame 25 and the second frame 26. Please refer to Figure 1 and Figure 2 The grating 225 is composed of a first silicon nitride layer 22, and the first frame 25, the second frame 26 and the multiple support arms 24 are all composed of a first silicon oxide layer 21 and a first silicon nitride layer 22 stacked together.
[0051] It should be noted that in the embodiments of this application, "multiple" can be two or more, such as three, four, five, six, seven, eight, etc.
[0052] Please combine Figure 4 The overall shape of the grating 225 can be circular, and the diameter of the grating 225 can be 100 micrometers to 900 micrometers, such as 100 micrometers, 200 micrometers, 300 micrometers, 400 micrometers, 500 micrometers, 600 micrometers, 700 micrometers, 800 micrometers, 900 micrometers, etc.
[0053] For example, the grating 225 includes a plurality of gratings spaced apart, each grating having a width of 1 micrometer to 3 micrometers (e.g., 1 micrometer, 2 micrometers, 3 micrometers, etc.), the spacing between any two gratings having a width of 1 micrometer to 3 micrometers (e.g., 1 micrometer, 2 micrometers, 3 micrometers, etc.), and the period of the grating 225 (the sum of the width of one grating and the width of one spacing) having a period of 2 micrometers to 6 micrometers (e.g., 2 micrometers, 3 micrometers, 4 micrometers, 5 micrometers, 6 micrometers, etc.).
[0054] Please combine Figure 3 The overall shape of the vibrating diaphragm 40 can be circular, and the diameter of the vibrating diaphragm 40 can be 100 mm to 900 mm, such as 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, etc.
[0055] Please see Figure 5 and Figure 6 The photoelectric conversion component 300 also includes a second substrate 310, on which the light source 320 and the detector 330 are both disposed.
[0056] For example, the material of the second substrate 310 includes silicon.
[0057] For example, detector 330 may include a photodiode.
[0058] For example, the light source 320 can be a vertical cavity surface-emitting laser (VCSEL).
[0059] For example, 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 micrometers to 900 micrometers, such as 100 micrometers, 200 micrometers, 300 micrometers, 400 micrometers, 500 micrometers, 600 micrometers, 700 micrometers, 800 micrometers, 900 micrometers, etc.
[0060] For example, 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 micrometers to 900 micrometers, such as 100 micrometers, 200 micrometers, 300 micrometers, 400 micrometers, 500 micrometers, 600 micrometers, 700 micrometers, 800 micrometers, 900 micrometers, etc.
[0061] Please see Figure 5 and Figure 6 The second substrate 310 is further provided with a first connector 321, a second connector 322, a driving circuit 323, and a first ground electrode 324. The driving circuit 323 is electrically connected to the second connector 322, and the first ground 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 through a wire 325. It can be 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.
[0062] Please see Figure 5 and Figure 6 The second substrate 310 is provided with multiple detectors 330, multiple filter circuits 331, multiple amplifier circuits 332, a differential circuit 333, and a second ground electrode 334. The multiple detectors 330 are respectively connected to the multiple filter circuits 331, the multiple filter circuits 331 are respectively connected to the multiple amplifier circuits 332, the multiple amplifier circuits 332 are all connected to the differential circuit 333, and the multiple detectors 330 are all connected to the second ground electrode 334.
[0063] For example, the light signals received by the multiple detectors 330 have different intensities. It should be noted that after the detectors 330 convert the received light signals into electrical signals, the filter circuit 331 can filter out interference signals in the electrical signals, reducing noise. The amplifier circuit 332 can amplify the intensity of the electrical signals, improving detection sensitivity. The electrical signals output by the multiple detectors 330, after being filtered to remove noise and amplified, are connected to the differential circuit 333. The differential circuit 333 subtracts the electrical signals from the multiple detectors 330 pairwise, thereby further filtering out interference signals. Specifically, the working principle of the differential circuit 333 is as follows: if the electrical signals of the multiple detectors 330 are all interfered with by noise signals, then the degree of interference from the noise signals on the electrical signals of the multiple detectors 330 is basically the same. Therefore, by subtracting the electrical signals of two detectors 330 and using the difference between the two electrical signals as the effective input signal, the input of the noise signal can be reduced to almost zero, thereby achieving the purpose of anti-interference.
[0064] For example, the driving circuit 323, the filter circuit 331, the amplifier circuit 332 and the differential circuit 333 can be formed by implanting N-type ions or P-type ions on the second substrate 310.
[0065] For example, the first grounding electrode 324 and the second grounding electrode 334 can be formed by electroplating, and the materials of the first grounding electrode 324 and the second grounding electrode 334 can both be metals, such as copper.
[0066] For example, the materials of the first connector 321 and the second connector 322 can both be metals, such as tin.
[0067] Please combine Figure 1 The emitted light from the light source 320 is not perpendicular to the surface of the grating 225 on the side away from the vibrating film 40. Understandably, when the emitted light from the light source 320 is perpendicular to the surface of the grating 225 on the side away from the vibrating film 40, the emitted light from the light source 320 will be directly reflected back into the light source 320 by the grating 225, causing the light source 320 to burn out.
[0068] Please combine Figure 5 The angle between the light-emitting surface of the light source 320 and the second substrate 310 is an acute angle, and the emitted light from 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.
[0069] Please combine Figure 1The optical microphone 100 also includes a carrier 400. The second substrate 310 of the photoelectric conversion component 300 is connected to the carrier 400, and the first substrate 10 of the microphone diaphragm 200 is connected to the carrier 400 via an adhesive 500. The adhesive 500 is disposed around the periphery of the photoelectric conversion component 300. It can be seen that the photoelectric conversion component 300 is enclosed within the space formed by the microphone diaphragm 200, the adhesive 500, and the carrier 400, thereby preventing the photoelectric conversion component 300 from being attacked by external water and oxygen, and thus extending the service life of the photoelectric conversion component 300. Exemplarily, the adhesive 500 may include epoxy resin. Exemplarily, the carrier 400 is flat, and the material of the carrier 400 may be metal, such as copper.
[0070] For example, the distance between the vibrating diaphragm 40 and the grating 225 can be 0.5mm to 3mm, such as 0.5mm, 1mm, 1.5mm, 2mm, 2.5mm, 3mm, etc.
[0071] Please see Figure 7 , Figure 7 A flowchart illustrating a method for manufacturing an optical microphone according to an embodiment of this application. This 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. This method may include:
[0072] S100 provides a microphone diaphragm and a photoelectric conversion component. The microphone diaphragm includes a spaced-apart vibrating diaphragm and a grating, and the vibrating diaphragm has 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 the light reflected back from the microphone diaphragm and convert the light signal into an electrical signal.
[0073] S200 connects the microphone diaphragm and the photoelectric conversion component, positioning the photoelectric conversion component on the side of the grating away from the vibrating film to obtain an optical microphone.
[0074] Please see Figures 8 to 16 "Providing a microphone diaphragm 200" may specifically include:
[0075] Please see Figure 8 A first substrate 10 is provided, and a first inorganic layer 20 is formed on the first substrate 10. Please refer to [link to relevant documentation]. Figure 9 The first inorganic layer 20 is patterned to form a grating pattern 201;
[0076] Please see Figure 10 A first electrode layer 51 is formed on the first inorganic layer 20;
[0077] Please see Figure 11A sacrificial layer 31 is deposited on the first electrode layer 51 and the first substrate 10. (See also...) Figure 12 The sacrificial layer 31 is patterned, and a filling portion 311, a support portion 312, and a groove 313 located between the support portion 312 and the filling portion 311 are formed on the sacrificial layer 31. The filling portion 311 is provided corresponding to the grating pattern 201, the support portion 312 is provided on the periphery of the filling portion 311, and the groove 313 penetrates the sacrificial layer 31 and separates the support portion 312 and the filling portion 311.
[0078] Please see Figure 13 A vibrational thin film 40 is formed on the sacrificial layer 31;
[0079] Please see Figure 14 A second electrode layer 52 is formed on the vibrating thin film 40;
[0080] Please see Figure 15 The first substrate 10 is patterned to form a first notch 27 corresponding to the grating pattern 201 on the first substrate 10.
[0081] Please see Figure 16 The sacrificial layer 31 is etched using an etchant, and the etchant etches the filling portion 311 through the first notch 27 to remove the filling portion 311, forming a gap between the vibrating film 40 and the grating pattern 201; the support portion 312 of the sacrificial layer 31 is not etched, forming a support member 30 for supporting the vibrating film 40.
[0082] For example, the materials of the first electrode layer 51 and the second electrode layer 52 can both be polycrystalline silicon. In some embodiments, the first electrode layer 51 and the second electrode layer 52 can be prepared by low pressure chemical vapor deposition (LPCVD).
[0083] Please combine Figure 2After etching the sacrificial layer 31 with an etchant, "providing the microphone diaphragm 200" may further include: forming a first reflective layer 61 on the side of the grating 225 away from the vibrating film 40 and a second reflective layer 62 on the side of the vibrating film 40 facing the grating 225 using a vapor deposition method (e.g., electron beam evaporation) to improve the reflectivity of the surfaces of the grating 225 and the vibrating film 40. For example, the materials of the first reflective layer 61 and the second reflective layer 62 are both metals, such as gold (Au). It is understood that during the vapor deposition process, the metal material diffuses in a gaseous state to the surface of the grating 225 to form the first reflective layer 61, and the gaseous metal material can pass through the gaps in the grating 225 to reach the surface of the vibrating film 40 to form the second reflective layer 62. That is to say, the first reflective layer 61 and the second reflective layer 62 can be formed in the same vapor deposition process.
[0084] Please combine Figure 8 and Figure 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 sequentially stacked on the first substrate 10.
[0085] For example, "forming a first inorganic layer 20 on the first substrate 10" may specifically include:
[0086] The surface of the first substrate 10 is oxidized to obtain a first silicon oxide layer 21;
[0087] A first silicon nitride layer 22 is formed on the first silicon oxide layer 21 using a chemical vapor deposition method.
[0088] For example, the surface of the first substrate 10 can be thermally oxidized to obtain a first silicon oxide layer 21.
[0089] For example, a first silicon nitride layer 22 can be formed on the first silicon oxide layer 21 using low pressure chemical vapor deposition (LPCVD).
[0090] For example, the material of the sacrificial layer 31 is silicon oxide; while etching the filling portion 311 of the sacrificial layer 31 through the first notch 27 with an etchant, the first silicon oxide layer 21 on the surface of the grating pattern 201 is etched away. It can be understood that since the material of the sacrificial layer 31 (silicon oxide) 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 with the same etchant.
[0091] For example, the first silicon oxide layer 21 on the surface of the grating pattern 201 can be removed by chemical mechanical polishing (CMP), thereby forming a cutout 215 corresponding to the grating 225 on the first silicon oxide layer 21. It is understood that CMP is a technique that combines chemical and mechanical action, that is, it uses a combination of etching solution etching and mechanical polishing to remove the first silicon oxide layer 21 on the surface of the grating pattern 201.
[0092] Please combine Figure 11 After depositing a sacrificial layer 31 on the first electrode layer 51 and the first substrate 10, a groove 314 is formed on the sacrificial layer 31 at a position corresponding to the vent hole 23. The groove 314 does not penetrate the filling portion 311, and the groove 314 is disposed around the periphery of the grating 225.
[0093] Please combine Figure 13 When a vibrating film 40 is formed on the sacrificial layer 31, the vibrating film 40 forms a curved portion 42 at the groove 314.
[0094] Please combine Figures 9 to 11 Since there is a depression at the position of the vent 23 on the first inorganic layer 20, the deposition material needs to fill the vent 23 first during the deposition of the sacrificial layer 31, resulting in a lower thickness of the sacrificial layer 31 at the position corresponding to the vent 23, thus forming a groove 314 relative to the surrounding area.
[0095] Please combine Figure 8 and Figure 9 After the first inorganic layer 20 is patterned, while forming the grating 225, a vent 23 can also be formed on the first inorganic layer 20. The vent 23 penetrates the first inorganic layer 20 and is located on the periphery of the grating 225.
[0096] Please combine Figure 15 After patterning the first substrate 10, 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 vent hole 23 is formed on the first substrate 10.
[0097] Please combine Figure 16 When the etchant is used to etch the sacrificial layer 31, while the etchant is etching the filling portion 311 through the first notch 27, the etchant is also etching the portion of the filling portion 311 located in the vent hole 23 through the second notch 28.
[0098] Please combine Figure 13 and Figure 3After the vibration film 40 is formed on the sacrificial layer 31, the vibration film 40 is patterned to form a sound inlet 41. The sound inlet 41 penetrates the vibration film 40. The orthogonal projection of the sound inlet 41 on the first substrate 10 is located between the orthogonal projection of the support 30 on the first substrate 10 and the orthogonal projection of the grating 225 on the first substrate 10.
[0099] Please combine Figure 5 Specifically, "providing photoelectric conversion component 300" may include: providing a second substrate 310, forming a detector 330 on the second substrate 310, and setting a light source 320 on the second substrate 310.
[0100] Please combine Figure 5 The material of the second substrate 310 includes silicon, and the detector 330 includes a photodiode;
[0101] "Forming detector 330 on second substrate 310" can specifically include: implanting P-type ions and N-type ions into second substrate 310 to form a PN junction, and the PN structure forms a photodiode.
[0102] Please combine Figure 6 "Providing photoelectric conversion component 300" may specifically include:
[0103] A first connector 321, a second connector 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 connector 322, and the first ground electrode 324 is electrically connected to the first connector 321.
[0104] Please see Figure 17 and Figure 18 Specifically, “setting a light source 320 on the second substrate 310” may include: providing a light source 320 having a first electrode and a second electrode, connecting the first electrode of the light source 320 to a first connector 321, and connecting the second electrode of the light source 320 to a second connector 322 using a wire 325.
[0105] For example, the first electrode layer 51 of the light source 320 can be connected to the first connector 321 by welding or bonding.
[0106] For example, the driving circuit 323 can be formed on the second substrate 310 by implanting P-type ions or N-type ions into the second substrate 310.
[0107] For example, the first connector 321, the second connector 322 and the first ground electrode 324 can be formed on the second substrate 310 by electroplating.
[0108] For example, the material of the wire 325 can be a metal, such as aluminum (Al).
[0109] Please combine Figure 6 The second substrate 310 is provided with multiple detectors 330. The "providing photoelectric conversion component 300" may further include: forming multiple filter circuits 331, multiple amplifier circuits 332, differential circuits 333 and a second ground electrode 334 on the second substrate 310; the multiple detectors 330 are respectively connected to the multiple filter circuits 331, the multiple filter circuits 331 are respectively connected to the multiple amplifier circuits 332, the multiple amplifier circuits 332 are all connected to the differential circuits 333, and the multiple detectors 330 are all connected to the second ground electrode 334.
[0110] For example, a filter circuit 331, an amplifier circuit 332, and a differential circuit 333 can be formed on the second substrate 310 by implanting P-type or N-type ions into the second substrate 310.
[0111] For example, the second ground electrode 334 can be formed on the second substrate 310 by electroplating.
[0112] Please combine Figure 1 "Connecting the microphone diaphragm 200 and the photoelectric conversion component 300" may specifically include:
[0113] A carrier 400 is provided to fix the second substrate 310 of the photoelectric conversion component 300 onto the carrier 400;
[0114] The first substrate 10 of the microphone diaphragm 200 is fixed to the carrier 400 with adhesive 500, which is disposed around the photoelectric conversion component 300.
[0115] The optical microphone and its manufacturing method provided in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. An optical microphone, characterized in that, include: A microphone diaphragm includes a first substrate, a first inorganic layer, a support member, and a vibrating film stacked sequentially. The first inorganic layer is disposed on the first substrate, and the support member is disposed between the first inorganic layer and the vibrating film. The first inorganic layer includes a grating, and the support member is disposed around the periphery of the grating. The vibrating film has a sound inlet hole that penetrates the vibrating film. 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 has a vent hole that penetrates the first inorganic layer, and the orthographic projection of the vent 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 includes a first silicon oxide layer and a first silicon nitride layer sequentially stacked on the first substrate. The grating is located on the first silicon nitride layer. A cutout is formed on the first silicon oxide layer corresponding to the position of the grating. A second notch corresponding to the vent hole is formed on the first substrate. A photoelectric conversion component is disposed on the side of the grating away from the vibrating diaphragm. 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 back from the microphone diaphragm and convert the light signal into an electrical signal.
2. The optical microphone according to claim 1, characterized in that, The grating has a first reflective layer on the side facing away from the vibrating film, and the vibrating film has a second reflective layer on the side facing the grating.
3. The optical microphone according to claim 1, characterized in that, A first electrode layer is provided on the side of the first inorganic layer away from the first substrate, and a second electrode layer is provided on the side of the vibrating thin film away from the first inorganic layer.
4. The optical microphone according to claim 1, characterized in that, The vibrating film has a curved portion that bends toward the first inorganic layer, and the orthographic projection of the curved 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.
5. The optical microphone according to claim 3, characterized in that, The materials of the first electrode layer and the second electrode layer both include polycrystalline silicon, and the material of the vibrating thin film includes silicon nitride.
6. The optical microphone according to claim 1, characterized in that, The photoelectric conversion component further includes a second substrate, on which both the light source and the detector are disposed; The second substrate is further provided with a first connector, a second connector, a driving circuit and a first ground electrode, wherein the driving circuit is electrically connected to the second connector and the first ground electrode is electrically connected to the first connector; The light source has a first electrode and a second electrode; the first electrode of the light source is connected to the first connector, and the second electrode of the light source is connected to the second connector via a wire.
7. The optical microphone according to claim 6, characterized in that, The second substrate is provided with a plurality of detectors, a plurality of filter circuits, a plurality of amplifier circuits, a differential circuit and a second ground electrode; the plurality of detectors are respectively connected to the plurality of filter circuits, the plurality of filter circuits are respectively connected to the plurality of amplifier circuits, the plurality of amplifier circuits are all connected to the differential circuit, and the plurality of detectors are all connected to the second ground electrode.
8. The optical microphone according to any one of claims 1-7, characterized in that, The emitted light from the light source is not perpendicular to the surface of the grating on the side opposite to the vibrating film.
9. The optical microphone according to any one of claims 1-7, characterized in that, The optical microphone also includes a carrier, the photoelectric conversion component is connected to the carrier, and the microphone diaphragm is connected to the carrier by an adhesive, the adhesive being disposed around the periphery of the photoelectric conversion component.
10. A method for manufacturing an optical microphone, characterized in that, include: A microphone diaphragm and a photoelectric conversion component are provided. The microphone diaphragm includes a first substrate, a first inorganic layer, a support member, and a vibrating film stacked sequentially. The first inorganic layer is disposed on the first substrate, and the support member is disposed between the first inorganic layer and the vibrating film. The first inorganic layer includes a grating, and the support member is disposed around the periphery of the grating. The vibrating film has a sound inlet hole that penetrates the vibrating film. 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 has a vent hole that penetrates the vibrating film. The first inorganic layer has the orthographic projection of the vent hole onto the first substrate located between the orthographic projection of the support member onto the first substrate and the orthographic projection of the grating onto the first substrate. The first inorganic layer includes a first silicon oxide layer and a first silicon nitride layer sequentially stacked on the first substrate. The grating is located on the first silicon nitride layer. A cutout is formed on the first silicon oxide layer corresponding to the position of the grating. A second notch is formed on the first substrate corresponding to the vent 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 the light reflected back from the microphone diaphragm and convert the light signal into an electrical signal. By connecting the microphone diaphragm and the photoelectric conversion component, and placing the photoelectric conversion component on the side of the grating away from the vibrating film, an optical microphone is obtained.
11. The method for manufacturing an optical microphone according to claim 10, characterized in that, The microphone diaphragm includes: A first substrate is provided, a first inorganic layer is formed on the first substrate, and the first inorganic layer is patterned to form a grating pattern; A first electrode layer is formed on the first inorganic layer; A sacrificial layer is deposited on the first electrode layer and the first substrate, and the sacrificial layer is patterned to form a filling portion, a support portion, and a trench located between the support portion and the filling portion. The filling portion is configured corresponding to the grating pattern, the support portion is disposed around the filling portion, and the trench penetrates the sacrificial layer and separates the support portion from the filling portion. A vibrational thin film is formed on the sacrificial layer; A second electrode layer is formed on the vibrating thin film; The first substrate is patterned to form a first notch corresponding to the grating pattern on the first substrate; The sacrificial layer is etched using an etching solution, which etches the filling portion through the first notch to remove the filling portion and form a gap between the vibrating film and the grating pattern; the supporting portion of the sacrificial layer is not etched, forming a support for supporting the vibrating film.
12. The method for manufacturing an optical microphone according to claim 11, characterized in that, The material of the first substrate includes silicon, and the first inorganic layer includes a first silicon oxide layer and a first silicon nitride layer sequentially stacked on the first substrate; The formation of the first inorganic layer on the first substrate includes: The surface of the first substrate is oxidized to obtain a first silicon oxide layer; A first silicon nitride layer is formed on the first silicon oxide layer using a chemical vapor deposition method.
13. The method for manufacturing an optical microphone according to claim 12, characterized in that, The sacrificial layer is made of silicon oxide. While etching the filling portion of the sacrificial layer through the first notch with an etchant, the first silicon oxide layer on the surface of the grating pattern is etched away to obtain the grating.
14. The method for manufacturing an optical microphone according to claim 11, characterized in that, After the first inorganic layer is patterned, a vent hole is formed on the first inorganic layer while forming the grating. The vent hole penetrates the first inorganic layer and is located on the periphery of the grating. After patterning the first substrate, a first notch corresponding to the grating pattern is formed on the first substrate; When the sacrificial layer is etched with an etchant, while the etchant corrodes the filling portion through the first notch, the etchant also corrodes the portion of the filling portion located inside the vent hole through the second notch.
15. The method for manufacturing an optical microphone according to claim 14, characterized in that, After depositing a sacrificial layer on the first electrode and the first substrate, a groove is formed on the sacrificial layer corresponding to the position of the vent hole; When a vibrating film is formed on the sacrificial layer, the vibrating film forms a bend at the groove.
16. The method for manufacturing an optical microphone according to claim 11, characterized in that, After forming a vibrating film on the sacrificial layer, the vibrating film is patterned to form a sound inlet hole. The sound inlet hole penetrates the vibrating 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.
17. The method for manufacturing an optical microphone according to claim 11, characterized in that, After etching the sacrificial layer with an etchant, the provision of the microphone diaphragm further includes: forming a first reflective layer on the side of the grating away from the vibrating film by vapor deposition and forming a second reflective layer on the side of the vibrating film facing the grating.
18. The method for manufacturing an optical microphone according to claim 10, characterized in that, The photoelectric conversion component includes: providing a second substrate, forming a detector on the second substrate, and disposing a light source on the second substrate.
19. The method for manufacturing an optical microphone according to claim 18, characterized in that, The material of the second substrate includes silicon, and the detector includes a photodiode; The formation 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, wherein the PN junction forms the photodiode.
20. The method for manufacturing an optical microphone according to claim 18, characterized in that, The photoelectric conversion component further includes: forming a first connector, a second connector, a driving circuit, and a first ground electrode on the second substrate, wherein the driving circuit is electrically connected to the second connector, and the first ground electrode is electrically connected to the first connector; The step of setting the light source on the second substrate includes: A light source is provided, the light source having a first electrode and a second electrode; the first electrode of the light source is connected to a first connector, and the second electrode of the light source is connected to the second connector by a wire.
21. The method for manufacturing an optical microphone according to claim 18, characterized in that, The second substrate is provided with a plurality of detectors, and the photoelectric conversion component further 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 detectors are respectively connected to the plurality of filter circuits, the plurality of filter circuits are respectively connected to the plurality of amplifier circuits, the plurality of amplifier circuits are all connected to the differential circuits, and the plurality of detectors are all connected to the second ground electrode.
22. The method for manufacturing an optical microphone according to any one of claims 10-21, characterized in that, The connection between the microphone diaphragm and the photoelectric conversion component includes: A carrier is provided to fix the photoelectric conversion component onto the carrier; The microphone diaphragm is fixed to the carrier with adhesive, which is disposed around the periphery of the photoelectric conversion component.