Acoustic sensor
By integrating the acoustic core and signal processing circuit in the acoustic sensor, the sound pressure signal is converted into electrical signals and optimized for processing, the stability and integration problems of traditional acoustic sensors in harsh environments are solved, and a higher degree of stability and integration is achieved.
Patent Information
- Application Number
- CN202510005123.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-02
- Publication Date
- 2025-04-25
AI Technical Summary
Traditional acoustic sensors have low stability in harsh environments and have low degree of integration after packaging, making it difficult to meet the needs of high precision and miniaturization.
An acoustic sensor is designed, including an acoustic core and a signal processing circuit. The acoustic core is packaged with an acoustic chip, which can convert the sound pressure signal into an electrical signal, and optimize the processing through the signal processing circuit, and finally pass it to the processor.
By integrating the acoustic core and signal processing circuit, the stability of the acoustic sensor and the degree of integration after packaging are improved, and it is suitable for vibration and noise monitoring in complex environments.
Smart Images
Figure CN119880122A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of semiconductors, and in particular, to an acoustic sensor. Background Art
[0002] With the rapid development of science and technology, the degree of automation in industrial production processes continues to improve. In order to ensure the stability of production operations and product quality, real-time monitoring of vibration and noise in the production environment has become particularly important. Traditional vibration and noise monitoring methods mainly rely on mechanical or optical sensors, but the performance of these sensors in harsh environments (such as high temperature, high pressure, strong corrosion, high-speed vibration, etc.) is often difficult to meet the requirements.
[0003] In order to improve the accuracy of sound monitoring, acoustic sensors are usually installed on mechanical equipment to monitor the sound of mechanical operation. Compared with traditional mechanical or optical sensors, acoustic sensors have the advantages of high accuracy, wide dynamic range, fast response speed, small size, light weight, low power consumption, etc., and are more suitable for vibration and noise monitoring in complex environments.
[0004] However, acoustic sensors are usually constructed using piezoelectric crystal materials, such as quartz crystals, piezoelectric ceramics, or piezoelectric ceramic films. Piezoelectric crystal materials have good piezoelectric properties and acoustic wave coupling characteristics, and can convert acoustic wave signals into electrical signals to achieve acoustic wave measurement. However, traditional acoustic sensors still have some problems and challenges in their applications.
[0005] First, traditional acoustic sensitive sensors have low sensitivity and response speed, and are difficult to adapt to high-speed or high-dynamic acoustic wave signals, which limits their application in high-precision measurements.
[0006] Secondly, the stability of traditional acoustic sensors is poor and they are easily affected by environmental factors such as temperature, humidity, and vibration, which affects the accuracy of the measured data. Especially in harsh environments such as extreme temperature, high pressure, and strong corrosion, the performance of traditional acoustic sensors will further decline.
[0007] Thirdly, the packaging technology of traditional acoustic sensitive sensors is poor, making it difficult to achieve miniaturization and integration, which limits their application in miniaturized and modular applications.
[0008] Currently, no effective solution has been proposed for the problems of low stability of acoustic sensors constructed using piezoelectric crystal materials and low degree of integration after packaging in related technologies. Summary of the invention
[0009] The present application provides an acoustic sensor to solve the problems in the related art that the acoustic sensor constructed by piezoelectric crystal materials has low stability and low integration after packaging.
[0010] According to one aspect of the present application, a sound sensor is provided. The sound sensor comprises: a sound-sensitive core body encapsulated with a sound-sensitive chip, wherein when the sound-sensitive chip receives a sound pressure signal, the sound-sensitive chip outputs an electrical signal proportional to the sound pressure signal, and inputs the electrical signal to a signal processing circuit through an output end of the sound-sensitive core body; a signal processing circuit connected to the output end of the sound-sensitive core body, for receiving the electrical signal sent by the sound-sensitive core body, processing the electrical signal, and sending the processed electrical signal to a processor.
[0011] Optionally, the acoustic sensor core further includes: a temperature compensation resistor, which is packaged in series with the acoustic sensor chip in the housing of the acoustic sensor core and is used to change the resistance value of the temperature compensation resistor according to the temperature change of the acoustic sensor core.
[0012] Optionally, the sound-sensitive core further includes: a pressure-conducting tube connected to the outer shell of the sound-sensitive core by glue, one end of the pressure-conducting tube is located inside the sound-sensitive core, and the other end is located outside the sound-sensitive core.
[0013] Optionally, the acoustic sensor core further includes: a gold wire for connecting the acoustic sensor chip with the temperature compensation resistor; and a protection module for encapsulating the acoustic sensor chip, wherein the protection module includes: a tube cap, a tube seat, and a filter.
[0014] Optionally, the acoustic sensor chip uses a silicon on insulator wafer as substrate silicon, uses an ion implantation process to construct multiple acoustic sensitive resistors on the top silicon of the silicon on insulator wafer, and uses the multiple acoustic sensitive resistors to form a Wheatstone bridge to obtain the acoustic sensor chip.
[0015] Optionally, the top silicon layer in the acoustic sensor chip is a beam membrane structure, wherein the acoustic sensor resistor is integrated on the beam membrane structure, so that the resistance of the acoustic sensor resistor changes with the vibration of the beam membrane structure.
[0016] Optionally, the resistance values of the plurality of acoustic resistors are the same.
[0017] Optionally, the conductivity type of the top silicon of the acoustic sensor chip is P type, and the conductivity type of the substrate silicon of the acoustic sensor chip is N type.
[0018] Optionally, the number of crystal directions of the silicon-on-insulator wafer is 100.
[0019] Optionally, the signal processing circuit includes: an amplifier circuit connected to the output end of the sound-sensitive core, used to receive and amplify the electrical signal sent by the sound-sensitive core; a filter circuit connected to the output end of the amplifier circuit, used to filter the amplified electrical signal to obtain a processed electrical signal.
[0020] Through this application, a sound-sensitive sensor is adopted, including: a sound-sensitive core body, which is encapsulated with a sound-sensitive chip, wherein when the sound-sensitive chip receives a sound pressure signal, the sound-sensitive chip outputs an electrical signal that is proportional to the sound pressure signal, and inputs the electrical signal into a signal processing circuit through the output end of the sound-sensitive core body; a signal processing circuit is connected to the output end of the sound-sensitive core body, and is used to receive the electrical signal sent by the sound-sensitive core body, and process the electrical signal, and send the processed electrical signal to a processor, thereby solving the problem of low stability of the sound-sensitive sensor constructed by piezoelectric crystal materials and low integration after packaging in the related art. By integrating the sound-sensitive core body and the signal processing circuit, the sound pressure signal is converted into an electrical signal by using the sound-sensitive chip and optimized, and finally transmitted to the processor, thereby achieving the technical effect of improving the stability of the sound-sensitive sensor and improving the integration degree after packaging. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:
[0022] Figure 1 is a schematic diagram of an acoustic sensor provided according to an embodiment of the present application;
[0023] Figure 2 This is a schematic diagram of a connection circuit of an optional temperature compensation resistor provided according to an embodiment of the present application;
[0024] Figure 3 It is a schematic diagram of the structure of an optional sound-sensitive core provided according to an embodiment of the present application. DETAILED DESCRIPTION
[0025] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.
[0026] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings 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 ordinary technicians in this field without creative work should fall within the scope of protection of the present application.
[0027] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.
[0028] It should be noted that the acoustic sensor determined in the present disclosure can be used in the semiconductor field, and can also be used in any field other than the semiconductor field. The application field of the acoustic sensor determined in the present disclosure is not limited.
[0029] For the convenience of description, some nouns or terms involved in the embodiments of the present application are explained below:
[0030] SOI silicon wafer: SOI (Silicon on Insulator) is a semiconductor technology that uses an insulating layer to isolate the silicon chip from the substrate to reduce electron diffraction and cross-coupling effects. SOI technology can improve transistor performance, reduce power consumption, and increase the speed and reliability of integrated circuits.
[0031] SIMOX technology: SIMOX (Separation by IMplanted Oxygen, molecular beam silicon oxide) technology is a semiconductor processing technology used to prepare SOI (Silicon on Insulator) substrates with specific structures and properties. This technology uses the implantation of oxygen ions in silicon wafers and the heat treatment process to embed a silicon oxide (SiO2) separation layer into the silicon wafer to form an SOI structure.
[0032] Wheatstone bridge: An instrument for measuring resistance, usually consisting of four resistors, two of which are known resistors and the other two are the resistors to be measured. By adjusting the known resistors to balance the bridge, the value of the resistor to be measured can be calculated. Wheatstone bridges are widely used in laboratories and industry to accurately measure resistance.
[0033] ICP etching: ICP (Inductively Coupled Plasma Etching) technology is a commonly used micro-nano processing technology, which is used for precise material etching in semiconductor device manufacturing and micro-nano processing. ICP etching uses high-frequency inductively coupled plasma to accelerate chemical reactions, thereby achieving high-precision etching of materials. This etching technology has the advantages of high speed, high precision, high selectivity and high uniformity.
[0034] RIE etching: RIE (Reactive Ion Etching) technology is a surface processing technology commonly used in semiconductor manufacturing and micro-nano processing to process micro-nano structures. In the RIE etching process, a high-energy ion beam is applied to the surface to cause a chemical reaction of the surface atoms or molecules, thereby achieving the etching of the material. This etching method has the advantages of high processing accuracy, high processing speed, and good surface quality.
[0035] According to an embodiment of the present application, an acoustic sensor is provided.
[0036] Figure 1 Schematic diagram of an acoustic sensor according to an embodiment of the present application. Figure 1 As shown, the acoustic sensor comprises:
[0037] The sound-sensitive core is encapsulated with a sound-sensitive chip. When the sound-sensitive chip receives a sound pressure signal, the sound-sensitive chip outputs an electrical signal that is proportional to the sound pressure signal, and inputs the electrical signal to a signal processing circuit through an output end of the sound-sensitive core.
[0038] Specifically, the sound pressure signal refers to the signal generated by the pressure wave produced by sound vibration in the air. The sound sensitive core is a structure encapsulated with a sound sensitive chip, wherein the sound sensitive chip is used to complete the operation of receiving the sound pressure signal and converting the sound pressure signal into an electrical signal, thereby completing the reception, processing and conversion operations of the sound pressure signal.
[0039] First, a sound-sensitive chip is made on a silicon wafer, and the sound-sensitive chip is packaged to obtain a sound-sensitive core. When a sound pressure signal acts on the silicon wafer, the sensitive resistance of the sound-sensitive chip changes, causing the perception of the sound signal. When the piezoresistance coefficient is π, the resistivity of the silicon wafer is ρ, and the stress of the silicon wafer is σ, the piezoresistance effect of the sound-sensitive chip can be expressed by formula (1):
[0040]
[0041] When the chip resistance R changes, the above formula can be converted into formula (2) according to the silicon wafer Poisson coefficient μ, silicon wafer strain ε, and silicon wafer elastic modulus E:
[0042]
[0043] When the injection resistor is placed on the edge of the sensitive diaphragm, the sensitive resistor can sense the stress in all directions and respond to the sound wave signal.
[0044] The signal processing circuit is connected to the output end of the sound-sensitive core, and is used to receive the electrical signal sent by the sound-sensitive core, process the electrical signal, and send the processed electrical signal to the processor.
[0045] Specifically, after the signal processing circuit receives the electrical signal sent by the acoustic chip in the acoustic core, since the electrical signal is unprocessed, the signal strength is poor and there is noise, it is necessary to amplify, filter, etc. the electrical signal, and then output the processed electrical signal to the processor, so that the processor can determine the sound information collected by the acoustic sensor based on the processed signal, and identify and process the sound information.
[0046] It should be noted that the signal processing circuit also needs to include a power supply unit, which not only needs to provide a high level to the signal processing unit, but also needs to power the sound sensitive chip. It can supply power to the constant current source through a constant voltage source, and provide current to the sound sensitive chip through the constant current source, thereby providing stable voltage and current for the sound sensitive chip and the signal processing circuit, ensuring the normal operation of the sound sensitive chip and the signal processing circuit and the accurate acquisition of sound signals.
[0047] The acoustic sensor provided by the embodiment of the present application adopts an acoustic core body and is encapsulated with an acoustic chip, wherein when the acoustic chip receives an acoustic pressure signal, the acoustic chip outputs an electrical signal proportional to the acoustic pressure signal, and inputs the electrical signal into a signal processing circuit through the output end of the acoustic core body; the signal processing circuit is connected to the output end of the acoustic core body, and is used to receive the electrical signal sent by the acoustic core body, and processes the electrical signal, and sends the processed electrical signal to a processor, thereby solving the problem that the acoustic sensor constructed by piezoelectric crystal materials in the related art has low stability and low integration after encapsulation. By integrating the acoustic core body and the signal processing circuit, the acoustic pressure signal is converted into an electrical signal by using the acoustic chip and optimized, and finally transmitted to the processor, thereby achieving the technical effect of improving the stability of the acoustic sensor and improving the integration after encapsulation.
[0048] Optionally, in the acoustic sensor provided in the embodiment of the present application, the acoustic core also includes: a temperature compensation resistor, which is packaged in series with the acoustic chip in the outer shell of the acoustic core, and is used to change the resistance value of the temperature compensation resistor according to the temperature change of the acoustic core.
[0049] Specifically, Figure 2 is a schematic diagram of a connection circuit of an optional temperature compensation resistor provided according to an embodiment of the present application, such as Figure 2 As shown, the temperature compensation resistor can be connected in series with the sound-sensitive chip and encapsulated in the shell of the sound-sensitive core, so that the temperature compensation resistor can perform temperature compensation operation on the sound-sensitive chip, thereby achieving the following technical effects:
[0050] Improve measurement accuracy: Since the acoustic chip may be affected by changes in ambient temperature during operation, resulting in errors in the measurement signal. The temperature compensation resistor can sense changes in ambient temperature and adjust its resistance value accordingly, thereby offsetting the impact of temperature changes on the measurement signal of the acoustic chip and improving the accuracy of the measurement.
[0051] Maintain circuit stability: In electronic devices, the temperature coefficients of different components may be different, which will cause temperature drift in the circuit. The addition of temperature compensation resistors can balance the temperature coefficient differences in the circuit, reduce temperature drift, and thus maintain the stability of the circuit. This is especially important for the acoustic sensor core, because a stable circuit can ensure the stability and reliability of the output signal of the acoustic sensor chip.
[0052] Extend service life: Temperature changes may have an adverse effect on the performance of the acoustic sensor chip, such as causing sensitivity to decrease or damage. By adding temperature compensation resistors, the impact of temperature changes on the acoustic sensor chip can be reduced, thereby extending its service life.
[0053] To sum up, the role of the temperature compensation resistor in the sound sensitive core is mainly to perform temperature compensation to improve the accuracy of measurement, maintain the stability of the circuit and extend the service life.
[0054] In order to ensure the stable operation of the acoustic sensor chip and improve the service life of the acoustic sensor chip, optionally, in the acoustic sensor provided in the embodiment of the present application, the acoustic sensor core also includes: a pressure-conducting tube, which is connected to the outer shell of the acoustic sensor core by glue, and one end of the pressure-conducting tube is located inside the acoustic sensor core, and the other end is located outside the acoustic sensor core.
[0055] Specifically, after the sound-sensitive chip and the temperature-compensating resistor are encapsulated in the outer shell, in order to isolate the sound-sensitive chip from the outside, it is necessary to connect the temperature-compensating resistor and the signal processing circuit through a wire, and then seal the connection between the temperature-compensating resistor and the signal processing circuit with glue, thereby ensuring that the sound-sensitive chip and the temperature-compensating resistor are isolated from the outside. However, this isolation method cannot guarantee the temperature and pressure inside the sound-sensitive core, so that when the sound-sensitive chip is working, the sound-sensitive chip will malfunction, resulting in failure to operate normally.
[0056] Therefore, the inside and outside of the core can be connected in a small range by passing the pressure tube through the glue, so that only properly treated fluids or gases can contact the acoustic sensitive core, thereby reducing the risk of damage to the acoustic sensitive resistor due to medium corrosion, pollution or physical impact. And in some applications, the acoustic sensitive core may need to withstand pressure changes from the external environment. The pressure tube can absorb and disperse these pressure changes through its structural design and material selection, thereby protecting the acoustic sensitive resistor from the impact of pressure shock.
[0057] Similarly, adding a conducting tube can also help maintain the operating temperature of the acoustic resistor within a relatively stable range through heat exchange with the fluid medium, which helps reduce the performance fluctuations of the acoustic resistor caused by temperature changes, thereby improving the overall stability and reliability of the acoustic core. And in certain specific fluid dynamic environments, the design of the pressure tube can optimize fluid flow and reduce the impact of adverse factors such as eddy currents and turbulence on the acoustic resistor. By optimizing the fluid flow path and reducing unnecessary fluid disturbances, the pressure tube can improve the measurement accuracy and stability of the acoustic resistor.
[0058] Optionally, in the acoustic sensor provided in the embodiment of the present application, the acoustic core further includes: a gold wire for connecting the acoustic chip to the temperature compensation resistor; and a protection module for encapsulating the acoustic chip, wherein the protection module includes: a tube cap, a tube seat, and a filter.
[0059] Specifically, Figure 3 is a schematic diagram of the structure of an optional acoustic sensitive core provided according to an embodiment of the present application, such as Figure 3 As shown, after obtaining the sound-sensitive chip and the temperature-compensating resistor, the sound-sensitive chip and the temperature-compensating resistor can be gold-wire welded using hot-press bonding technology, the tube seat, the filter screen and the tube cap can be welded together using hydrogen arc welding, and the signal processing circuit outside the package can be isolated using glue to obtain the sound-sensitive core.
[0060] The main function of the pipe cap is to protect the port of the acoustic resistor and prevent external factors such as debris and moisture from entering the pipe. This helps to ensure the stability and accuracy of the propagation of sound waves in the pipe and prevent external factors from interfering with the normal operation of the acoustic resistor. The filter can prevent impurities such as dust and moisture from entering the interior of the acoustic component, protecting it from contamination and damage.
[0061] Optionally, in the acoustic sensor provided in the embodiment of the present application, the acoustic sensor chip uses a silicon wafer on an insulator as substrate silicon, and uses an ion implantation process to construct multiple acoustic resistors on the top silicon of the silicon wafer on an insulator, and the multiple acoustic resistors form a Wheatstone bridge to obtain a acoustic sensor chip.
[0062] Specifically, the acoustic sensitive chip uses SOI silicon wafer as the substrate material, and uses ion implantation technology to design four acoustic sensitive resistors on the silicon wafer to form a Wheatstone bridge. The structural diaphragm is made using ICP etching technology, and the silicon wafer and borosilicate glass sheet are sealed together through electrostatic bonding to form a sound sensitive chip.
[0063] It should be noted that when constructing a sound-sensitive chip, the sound-sensitive resistor on the sound-sensitive chip can be made through an ion implantation process. First, the required ions can be designed and prepared, and the ions can be implanted into the top silicon according to the preset size parameters of the sound-sensitive resistor in the arrangement of the Wheatstone bridge. By changing the conductivity of the silicon, the required resistance area can be formed. After the ion implantation, the substrate silicon can be heat-treated to restore its crystal structure and stabilize the resistance value; then, through a photolithography process, that is, a layer of photoresist is coated on the top silicon, and a photolithography machine is used to project the designed layout of the sound-sensitive resistor strip onto the photoresist, and through the development and fixing steps, specific areas on the photoresist are removed or retained to form a photolithography pattern; finally, the RIE etching process can be used to etch the top silicon to produce a sound-sensitive resistor of corresponding size. The RIE process combines chemical reactions and physical bombardment, and can efficiently remove silicon materials that are not protected by photoresist. By precisely controlling the etching time and gas composition, a sound-sensitive resistor with a specific shape and size is formed.
[0064] Optionally, in the acoustic sensor provided in the embodiment of the present application, the top silicon layer in the acoustic chip is a beam membrane structure, wherein the acoustic resistor is integrated on the beam membrane structure, so that the resistance of the acoustic resistor changes with the vibration of the beam membrane structure.
[0065] Specifically, using ICP etching or other micro-nano processing technologies, a beam-membrane structure with a specific shape and size can be made on the top silicon, thereby obtaining a sound-sensitive chip. In the process of constructing the beam-membrane structure, the sound-sensitive resistor is positioned and integrated on the beam-membrane structure, so that when the sound wave acts on the sound-sensitive chip, it will cause the vibration of the beam-membrane structure, thereby causing the resistance of the sound-sensitive resistor to change. This resistance change will break the equilibrium state of the Wheatstone bridge, thereby generating a voltage difference or current difference at the output end of the bridge, realizing the conversion from sound waves to electrical signals. Since this difference is proportional to the change in resistance value, even if the resistance of the sound-sensitive resistor changes very little, a large output voltage or current change can be generated through the bridge. This amplification effect enables the sound-sensitive chip to detect sound wave signals more sensitively and convert them into electrical signals that are easy to process and transmit.
[0066] Optionally, in the acoustic sensor provided in the embodiment of the present application, the resistance values of the multiple acoustic resistors are the same.
[0067] Specifically, when constructing the resistors of the acoustic chip, the resistance values of multiple acoustic resistors need to be set to the same resistance value, and the geometric shapes and sizes of the designed multiple resistor strips need to be consistent, and the ion implantation dose concentration must be consistent, so as to ensure that the multiple resistors are exactly the same. In addition, multiple sensitive resistors should be placed in the stress-sensitive area to maximize the change of the sensitive resistors, and the longitudinal piezoresistance coefficient and the transverse piezoresistance coefficient should be reasonably utilized, and the longitudinal piezoresistance coefficient offset effect brought by the transverse piezoresistance coefficient should be fully considered. Therefore, the selection of a suitable SOI silicon wafer requires that the transverse piezoresistance coefficient of its sensitive resistor is as small as possible. At the same time, the concentration of ion implantation in the semiconductor process is required to be the same, and resistors of the same resistance value should be manufactured as much as possible. Two sensitive resistors are placed near the edge of the membrane, and the other two are placed near the center of the membrane. In this way, a better piezoresistance effect can be obtained, thereby ensuring the accuracy of the acoustic chip in acquiring sound signals.
[0068] Optionally, in the acoustic sensor provided in the embodiment of the present application, the conductivity type of the top silicon of the acoustic sensor chip is P-type, and the conductivity type of the substrate silicon of the acoustic sensor chip is N-type.
[0069] Optionally, in the acoustic sensor provided in the embodiment of the present application, the number of crystal orientations of the silicon wafer on insulator is 100.
[0070] Specifically, when the doping concentration on the surface of the silicon wafer is higher, the piezoresistance coefficient π value of the silicon wafer is smaller, and the temperature effect is smaller. When selecting silicon wafers, specific requirements can be made for the doping concentration and conductivity type. For N-type silicon wafers, the longitudinal piezoresistance coefficient in the 100 crystal direction is relatively large. When using N-type silicon to make sensitive resistors, since the piezoresistance coefficient on N-type silicon is very nonlinear, and in other crystal directions, the piezoresistance coefficient of N-type silicon is relatively small, therefore, the material of the sensitive resistor on the acoustic sensor chip is selected as P-type silicon. Since the sensitive resistor is constructed by using an ion implantation process on the top silicon, the conductivity type of the top silicon is P-type.
[0071] Furthermore, considering the process of making beam membrane structure by ICP etching method, the substrate material SOI silicon wafer crystal orientation will be selected <100> Crystal orientation. At the same time, the SOI substrate made by SIMOX process technology is selected. The silicon substrate is N-type. SIMOX uses ion implantation technology under the surface of the silicon layer to inject a large dose of oxygen or nitrogen to form silicon dioxide or silicon nitride in the buried layer to form an SOI silicon wafer. Light boron is implanted on the silicon single crystal. The sensitive resistor strip is etched using a dry etching process, and S is deposited using a low-pressure chemical vapor deposition method. 13 N4 film, and then use ICP etching technology to make beam membrane structure on silicon wafer; perform lead hole photolithography to make metal aluminum electrode. After completing the above steps, the chip is anodic bonded and separated.
[0072] It should be noted that single crystal silicon, as a sensitive material, has a very high sensitivity. When a sensitive resistor is constructed from single crystal silicon, the sensor can be guaranteed to have a large sensitivity and a relatively high output. Due to the dielectric isolation effect of the oxide layer of the SOI substrate itself, the leakage current is reduced between the sensitive resistor and the silicon substrate, and the high temperature resistance of the sensor is significantly improved. The manufacturing process of the SOI acoustic sensor chip is compatible with the manufacturing process of the processing circuit, and it is easy to achieve integration. Therefore, SOI silicon wafers can be selected as substrate materials. At the same time, when selecting SOI silicon wafers, the doping concentration and type requirements of the device layer can be proposed, and the concentration range can be adjusted by semiconductor ion implantation, so that the construction operation of the acoustic sensor chip can be completed through the above process.
[0073] Optionally, in the acoustic sensor provided in the embodiment of the present application, the signal processing circuit includes: an amplifier circuit, connected to the output end of the acoustic sensitive core, for receiving and amplifying the electrical signal sent by the acoustic sensitive core; a filter circuit, connected to the output end of the amplifier circuit, for filtering the amplified electrical signal to obtain a processed electrical signal.
[0074] Specifically, since the signal strength of the electrical signal output by the acoustic chip is relatively poor, in order to improve the ability to analyze the signal, it is necessary to amplify the electrical signal through an amplification circuit, thereby ensuring the accuracy and clarity of the electrical signal.
[0075] Furthermore, the function of the filter is to allow signals within a certain frequency range to pass through and filter out or suppress signals of other frequencies. Since electrical signals may contain clutter, noise and other signal contents, it is necessary to filter irrelevant signals to ensure the accuracy of the electrical signals output to the processor.
[0076] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.
[0077] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.
Claims
1. An acoustic sensor, characterized in that: include: A sound-sensitive core body encapsulated with a sound-sensitive chip, wherein when the sound-sensitive chip receives a sound pressure signal, the sound-sensitive chip outputs an electrical signal proportional to the sound pressure signal, and inputs the electrical signal into a signal processing circuit through an output end of the sound-sensitive core body; The signal processing circuit is connected to the output end of the sound-sensitive core, and is used to receive the electrical signal sent by the sound-sensitive core, process the electrical signal, and send the processed electrical signal to the processor.
2. The acoustic sensor according to claim 1, characterized in that: The acoustically sensitive core further comprises: A temperature compensation resistor is packaged in series with the acoustic sensor chip in the housing of the acoustic sensor core and is used to change the resistance value of the temperature compensation resistor according to the temperature change of the acoustic sensor core.
3. The acoustic sensor according to claim 2, characterized in that: The acoustically sensitive core further comprises: The pressure-conducting tube is connected to the outer shell of the sound-sensitive core through glue, one end of the pressure-conducting tube is located inside the sound-sensitive core, and the other end is located outside the sound-sensitive core.
4. The acoustic sensor according to claim 2, characterized in that: The acoustically sensitive core further comprises: Gold wire, used to connect the acoustic sensor chip to the temperature compensation resistor; A protection module is used to encapsulate the acoustic sensor chip, wherein the protection module includes: a tube cap, a tube seat, and a filter.
5. The acoustic sensor according to claim 1, characterized in that: The acoustic sensor chip uses a silicon-on-insulator wafer as substrate silicon, uses an ion implantation process to construct multiple acoustic resistors on the top silicon of the silicon-on-insulator wafer, and the multiple acoustic resistors form a Wheatstone bridge to obtain the acoustic sensor chip.
6. The acoustic sensor according to claim 5, characterized in that: The top silicon layer in the acoustic sensor chip is a beam membrane structure, wherein the acoustic resistor is integrated on the beam membrane structure, so that the resistance value of the acoustic resistor changes with the vibration of the beam membrane structure.
7. The acoustic sensor according to claim 5, characterized in that: The resistance values of the multiple acoustic resistors are the same.
8. The acoustic sensor according to claim 5, characterized in that: The conductivity type of the top silicon of the acoustic sensor chip is P type, and the conductivity type of the substrate silicon of the acoustic sensor chip is N type.
9. The acoustic sensor according to claim 5, characterized in that: The number of crystal directions of the silicon-on-insulator wafer is 100.
10. The acoustic sensor according to claim 1, characterized in that: The signal processing circuit comprises: an amplifier circuit, connected to the output end of the acoustic-sensitive core, and used for receiving and amplifying the electrical signal sent by the acoustic-sensitive core; The filter circuit is connected to the output end of the amplifier circuit and is used to filter the amplified electrical signal to obtain the processed electrical signal.