WO2021218233A1 - 压电声学传感器及其制造方法 - Google Patents

压电声学传感器及其制造方法 Download PDF

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Publication number
WO2021218233A1
WO2021218233A1 PCT/CN2021/070491 CN2021070491W WO2021218233A1 WO 2021218233 A1 WO2021218233 A1 WO 2021218233A1 CN 2021070491 W CN2021070491 W CN 2021070491W WO 2021218233 A1 WO2021218233 A1 WO 2021218233A1
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WIPO (PCT)
Prior art keywords
piezoelectric
unit
electrode
hollow structure
acoustic sensor
Prior art date
Application number
PCT/CN2021/070491
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English (en)
French (fr)
Inventor
冯志宏
姚丹阳
徐景辉
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华为技术有限公司
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Application filed by 华为技术有限公司 filed Critical 华为技术有限公司
Priority to EP21796082.2A priority Critical patent/EP4132008A4/en
Publication of WO2021218233A1 publication Critical patent/WO2021218233A1/zh
Priority to US17/974,326 priority patent/US20230043470A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
    • G01H11/00—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties
    • G01H11/06—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means
    • G01H11/08—Measuring mechanical vibrations or ultrasonic, sonic or infrasonic waves by detecting changes in electric or magnetic properties by electric means using piezoelectric devices
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R7/00—Diaphragms for electromechanical transducers; Cones
    • H04R7/16—Mounting or tensioning of diaphragms or cones
    • H04R7/18—Mounting or tensioning of diaphragms or cones at the periphery
    • H04R7/20—Securing diaphragm or cone resiliently to support by flexible material, springs, cords, or strands
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R31/00—Apparatus or processes specially adapted for the manufacture of transducers or diaphragms therefor
    • H04R31/006—Interconnection of transducer parts
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
    • H04R17/02—Microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R2201/00—Details of transducers, loudspeakers or microphones covered by H04R1/00 but not provided for in any of its subgroups
    • H04R2201/003—Mems transducers or their use

Definitions

  • This application relates to the field of electronic technology, and in particular to a piezoelectric acoustic sensor and a manufacturing method thereof.
  • a piezoelectric acoustic sensor can be set in the microphone to collect sound.
  • the piezoelectric acoustic sensor has many advantages such as high signal-to-noise ratio, low power consumption, and high sensitivity.
  • the piezoelectric acoustic sensor includes electrodes and piezoelectric materials.
  • the acoustic signal causes the piezoelectric material to vibrate, the area where the stress is concentrated in the piezoelectric material will generate a potential difference between the upper and lower electrodes, so that the acoustic signal can be converted into an electrical signal and extracted.
  • the piezoelectric acoustic sensor adopts a cantilever beam structure.
  • the cantilever beam will bend after being compressed by sound pressure, and its bending stress will generate an electrical signal.
  • there will be residual stress in the cantilever beam which will cause the cantilever beam to warp, which will increase the gap of the cantilever beam, and cause the acoustic leakage of the piezoelectric acoustic sensor to increase.
  • Resonance frequency and sensitivity affect.
  • This application provides a piezoelectric acoustic sensor and a manufacturing method thereof, which helps to improve the consistency of the resonance frequency and sensitivity of the piezoelectric acoustic sensor.
  • a piezoelectric acoustic sensor in one aspect, includes an anchor unit, a piezoelectric unit, a support unit, and a hollow structure.
  • a back cavity is formed in the anchor unit.
  • the piezoelectric unit is used to convert the acoustic signal entering the back cavity into an electrical signal.
  • the supporting unit covers the anchor unit and the piezoelectric unit.
  • the hollow structure is connected between the anchor unit and the piezoelectric unit, and is embedded in the support unit.
  • the anchor unit is used to fix various components in the piezoelectric acoustic sensor, and other components in the piezoelectric acoustic sensor are formed on the anchor unit.
  • the anchor unit has a back cavity, which is a sound inlet hole, and the piezoelectric unit is suspended above the back cavity to sense sound.
  • the anchor unit includes a substrate layer and an insulating layer, and the insulating layer covers the substrate layer.
  • the piezoelectric unit may be a piezoelectric stacked film, which may include electrodes and piezoelectric materials. Piezoelectric units can convert mechanical motion into electrical signals. Specifically, when the acoustic signal causes the piezoelectric material to vibrate, the area where the stress is concentrated in the piezoelectric material will generate a potential difference between the upper and lower electrodes, so that the acoustic signal can be converted into an electrical signal and extracted.
  • the support unit is used to fix the positions of the anchor unit, the hollow structure and the piezoelectric unit, so as to enhance the mechanical strength of the piezoelectric acoustic sensor. Since the hollow structure is connected between the anchor unit and the piezoelectric unit, after the support unit covers the anchor unit and the piezoelectric unit, the support unit will wrap the hollow structure, that is, the hollow structure will be embedded in the support unit . In this case, the support unit will fill the hollow gap in the hollow structure, so that the intrinsic resonance frequency of the piezoelectric acoustic sensor can be adjusted, the sound leakage caused by the hollow gap can be reduced, and the low frequency response performance of the piezoelectric acoustic sensor can be improved.
  • the hollow structure is a mechanical structure that removes part of the material, and has the characteristics of low rigidity and easy deformation.
  • the shape of the hollow structure member may be a bent shape, a back shape, or a grid shape.
  • the hollow structure can play a role in stress relief.
  • the number of hollow structural members can be greater than or equal to two. Further, the at least two hollow structure members can also be evenly distributed around the piezoelectric unit.
  • the piezoelectric unit may be a unimorph, and the piezoelectric unit may include a lower electrode, a piezoelectric material, and an upper electrode, and the piezoelectric material is located between the lower electrode and the upper electrode.
  • the upper surface of the piezoelectric unit is entirely covered with the support unit. In this way, the existence of the support unit can make the neutral axis of the piezoelectric unit far away from the center of the piezoelectric unit (that is, away from the piezoelectric material), so that the charge output and sensitivity of the piezoelectric acoustic sensor can be effectively improved.
  • the piezoelectric unit may be a piezoelectric bimorph, and the piezoelectric unit may include a lower electrode, a first piezoelectric material, a middle electrode, a second piezoelectric material, and an upper electrode.
  • the first piezoelectric material is located between the lower electrode and the middle electrode
  • the second piezoelectric material is located between the middle electrode and the upper electrode.
  • the upper surface of the piezoelectric unit is partially covered with the support unit. In this way, it can be ensured that the neutral axis of the piezoelectric unit is located in the middle electrode of the piezoelectric unit, so as not to affect the charge output and sensitivity of the piezoelectric acoustic sensor.
  • the hollow structure member may be connected to at least one of the electrode in the piezoelectric unit and the piezoelectric material.
  • the hollow structure member and the electrode to which it is connected can be made of the same material.
  • the hollow structure can be the same material as the piezoelectric material to which it is connected.
  • the hollow structure member When the hollow structure is connected to the electrode and piezoelectric material in the piezoelectric unit, that is, when a part of the hollow structure is connected to the electrode in the piezoelectric unit and the other part is connected to the piezoelectric material in the piezoelectric unit At this time, a part of the hollow structure member and the connected electrode may use the same material, and the other part of the hollow structure member may use the same material as the connected piezoelectric material.
  • the hollow structure member may be a multilayer structure, each layer in the hollow structure member may be connected to an electrode or piezoelectric material, and each layer and the electrode or piezoelectric material connected to it use the same material.
  • the hollow structure connected to the electrode or piezoelectric material can be manufactured while manufacturing the electrode or piezoelectric material in the piezoelectric unit, thereby simplifying the manufacturing process and saving manufacturing cost and manufacturing time.
  • the sacrificial layer is often formed first, then the piezoelectric unit is formed on the sacrificial layer, and then the sacrificial layer is removed.
  • the hollow structure can serve as a mechanical connection.
  • the piezoelectric unit can be connected to the anchor unit through the hollow structure, thereby avoiding piezoelectric The cell falls off during the removal of the sacrificial layer.
  • the hollow structure can play a role in stress relief.
  • the hollow structure with low stiffness and easy deformation allows the piezoelectric unit to move through the change of the hollow gap (such as up and down). Bending or horizontal expansion), the residual stress of the piezoelectric unit is released through the deformable hollow structure to achieve zero residual stress. Since the residual stress of the piezoelectric unit has been released, the piezoelectric acoustic sensor of the same geometric size has a consistent resonance frequency and sensitivity.
  • a method for manufacturing a piezoelectric acoustic sensor is provided.
  • an anchor unit is provided, a groove is etched on the upper surface of the anchor unit, and then the sacrificial layer is filled in the groove.
  • a piezoelectric unit is formed on the sacrificial layer, and a hollow structure is formed on the anchor unit and the sacrificial layer.
  • the area of the lower surface of the piezoelectric unit is smaller than the area of the upper surface of the sacrificial layer, and the hollow structure is connected to the anchor unit Between and the piezoelectric unit. After that, the sacrificial layer is removed.
  • a support unit is formed on the anchor unit and the piezoelectric unit, and the support unit is wrapped outside the hollow structure. Finally, the back cavity is etched at the position between the bottom of the groove and the lower surface of the anchor unit to obtain a piezoelectric acoustic sensor.
  • the anchor unit is used to fix various components in the piezoelectric acoustic sensor, and other components in the piezoelectric acoustic sensor can be formed on the anchor unit.
  • the anchor unit may include a substrate layer and an insulating layer. In this case, when an anchor unit is provided, a substrate layer can be provided first, and then an insulating layer can be formed on the substrate layer.
  • the piezoelectric unit may be a piezoelectric stacked film, which may include electrodes and piezoelectric materials. Piezoelectric units can convert mechanical motion into electrical signals. Specifically, when the acoustic signal causes the piezoelectric material to vibrate, the area where the stress is concentrated in the piezoelectric material will generate a potential difference between the upper and lower electrodes, so that the acoustic signal can be converted into an electrical signal and extracted.
  • the area of the lower surface of the piezoelectric unit is smaller than the area of the upper surface of the sacrificial layer, that is, the piezoelectric unit is completely located on the upper surface of the sacrificial layer.
  • the hollow structure is a mechanical structure that removes part of the material, and has the characteristics of low rigidity and easy deformation.
  • the shape of the hollow structure may be a bent shape, a back shape, or a grid shape.
  • the hollow structure can play a role in stress relief.
  • the number of hollow structural members can be greater than or equal to two. Further, the at least two hollow structure members can also be evenly distributed around the piezoelectric unit.
  • the support unit is used to fix the positions of the anchor unit, the hollow structure and the piezoelectric unit, so as to enhance the mechanical strength of the piezoelectric acoustic sensor. Since the hollow structure is connected between the anchor unit and the piezoelectric unit, after the support unit is formed on the anchor unit and the piezoelectric unit, the support unit will wrap the outside of the hollow structure. In other words, the supporting unit covers the anchor unit and the piezoelectric unit, and the hollow structure is embedded in the supporting unit.
  • the support unit fills the hollow gap in the hollow structure member, so that the intrinsic resonance frequency of the finally manufactured piezoelectric acoustic sensor can be adjusted, the sound leakage caused by the hollow gap can be reduced, and the low frequency response performance of the piezoelectric acoustic sensor can be improved.
  • the piezoelectric unit may be a unimorph, and the piezoelectric unit may include a lower electrode, a piezoelectric material, and an upper electrode.
  • the lower electrode may be formed on the sacrificial layer
  • the piezoelectric material may be formed on the lower electrode
  • the upper electrode may be formed on the piezoelectric material.
  • the upper surface of the piezoelectric unit is entirely covered with the supporting unit.
  • the existence of the support unit can make the neutral axis of the piezoelectric unit far away from the center of the piezoelectric unit (that is, away from the piezoelectric material), thereby effectively improving the charge output and sensitivity of the finally manufactured piezoelectric acoustic sensor.
  • the piezoelectric unit may be a piezoelectric bimorph, and the piezoelectric unit may include a lower electrode, a first piezoelectric material, a middle electrode, a second piezoelectric material, and an upper electrode.
  • the lower electrode may be formed on the sacrificial layer
  • the first piezoelectric material may be formed on the lower electrode
  • the middle electrode may be formed on the first piezoelectric material.
  • a second piezoelectric material is formed on the middle electrode
  • an upper electrode is formed on the second piezoelectric material.
  • the support unit When forming the support unit on the anchor unit and the piezoelectric unit, the support unit can be deposited on the upper surface of the anchor unit and the upper surface of the piezoelectric unit first, and the deposited support unit will wrap the hollow structure and then remove it At least a part of the supporting unit deposited on the upper surface of the piezoelectric unit.
  • the upper surface of the piezoelectric unit is partially covered with the supporting unit, so that the neutral axis of the piezoelectric unit is located in the middle electrode of the piezoelectric unit, so as not to affect the electric charge of the piezoelectric acoustic sensor finally manufactured. Output and sensitivity.
  • the hollow structure member may be connected to at least one of the electrode in the piezoelectric unit and the piezoelectric material.
  • the hollow structure member and the electrode to which it is connected can be made of the same material.
  • the hollow structure can be the same material as the piezoelectric material to which it is connected.
  • the hollow structure member When the hollow structure is connected to the electrode and piezoelectric material in the piezoelectric unit, that is, when a part of the hollow structure is connected to the electrode in the piezoelectric unit and the other part is connected to the piezoelectric material in the piezoelectric unit At this time, a part of the hollow structure member and the connected electrode may use the same material, and the other part of the hollow structure member may use the same material as the connected piezoelectric material.
  • the hollow structure member may be a multilayer structure, each layer in the hollow structure member may be connected to an electrode or piezoelectric material, and each layer and the electrode or piezoelectric material connected to it use the same material.
  • the hollow structure connected to the electrode or piezoelectric material can be manufactured while manufacturing the electrode or piezoelectric material in the piezoelectric unit, thereby simplifying the manufacturing process and saving manufacturing cost and manufacturing time.
  • the hollow structure can serve as a mechanical connection.
  • the piezoelectric unit In the process of removing the sacrificial layer under the piezoelectric unit, the piezoelectric unit can be connected to the anchor unit through the hollow structure, thereby avoiding piezoelectricity. The unit falls off during the removal of the sacrificial layer, and the piezoelectric unit can be suspended above the groove through the hollow structure.
  • the hollow structure can play a role in stress relief.
  • the hollow structure with low stiffness and easy deformation allows the piezoelectric unit to move through the change of the hollow gap (such as up and down).
  • the residual stress of the piezoelectric unit is released through the deformable hollow structure to achieve zero residual stress. Since the residual stress of the piezoelectric unit has been released, the finally manufactured piezoelectric acoustic sensor of the same geometric size has the same resonant frequency and sensitivity.
  • the piezoelectric acoustic sensor includes an anchor unit, a piezoelectric unit, a support unit and a hollow structure.
  • a back cavity is formed in the anchor unit.
  • the piezoelectric unit is used to convert the acoustic signal entering the back cavity into an electrical signal.
  • the supporting unit covers the anchor unit and the piezoelectric unit.
  • the hollow structure is connected between the anchor unit and the piezoelectric unit, and is embedded in the support unit.
  • the residual stress of the piezoelectric unit can be released by the deformable hollow structure during the manufacturing process to achieve zero residual stress, thus avoiding the resonant frequency drift of the piezoelectric acoustic sensor and avoiding the sensitivity reduction of the piezoelectric acoustic sensor, thereby helping To improve the performance consistency of piezoelectric acoustic sensors.
  • FIG. 1 is a schematic diagram of a sound pickup system provided by an embodiment of the present application
  • FIG. 2 is a schematic diagram of another sound pickup system provided by an embodiment of the present application.
  • FIG. 3 is a schematic diagram of another sound pickup system provided by an embodiment of the present application.
  • FIG. 4 is a schematic structural diagram of a first piezoelectric acoustic sensor provided by an embodiment of the present application.
  • Fig. 5 is a schematic structural diagram of a second piezoelectric acoustic sensor provided by an embodiment of the present application.
  • Fig. 6 is a schematic structural diagram of a third piezoelectric acoustic sensor provided by an embodiment of the present application.
  • FIG. 7 is a schematic structural diagram of a fourth piezoelectric acoustic sensor provided by an embodiment of the present application.
  • FIG. 8 is a schematic structural diagram of a fifth piezoelectric acoustic sensor provided by an embodiment of the present application.
  • Fig. 9 is a schematic structural diagram of a sixth piezoelectric acoustic sensor provided by an embodiment of the present application.
  • FIG. 10 is a schematic diagram of a neutral axis of a piezoelectric unit provided by an embodiment of the present application.
  • FIG. 11 is a schematic diagram of the neutral axis of another piezoelectric unit provided by an embodiment of the present application.
  • FIG. 12 is a schematic structural diagram of a hollow structure provided by an embodiment of the present application.
  • FIG. 13 is a schematic structural diagram of another hollow structure provided by an embodiment of the present application.
  • FIG. 14 is a schematic diagram of another hollow structure provided by an embodiment of the present application.
  • FIG. 15 is a schematic diagram of the connection between a hollow structure and a piezoelectric unit provided by an embodiment of the present application.
  • FIG. 16 is a schematic diagram of the connection between another hollow structure member and a piezoelectric unit provided by an embodiment of the present application.
  • FIG. 17 is a schematic diagram of the connection between still another hollow structure component and a piezoelectric unit provided by an embodiment of the present application.
  • FIG. 18 is a schematic structural diagram of a seventh piezoelectric acoustic sensor provided by an embodiment of the present application.
  • FIG. 19 is a schematic structural diagram of an eighth piezoelectric acoustic sensor provided by an embodiment of the present application.
  • FIG. 20 is a schematic structural diagram of a ninth piezoelectric acoustic sensor provided by an embodiment of the present application.
  • 21 is a schematic structural diagram of a tenth piezoelectric acoustic sensor provided by an embodiment of the present application.
  • 22 is a schematic structural diagram of an eleventh piezoelectric acoustic sensor provided by an embodiment of the present application.
  • FIG. 23 is a schematic structural diagram of a twelfth piezoelectric acoustic sensor provided by an embodiment of the present application.
  • FIG. 24 is a schematic diagram of a removal process of a sacrificial layer provided by an embodiment of the present application.
  • 25 is a schematic diagram of another sacrificial layer removal process provided by an embodiment of the present application.
  • FIG. 26 is a flowchart of a method for manufacturing a piezoelectric acoustic sensor according to an embodiment of the present application
  • FIG. 27 is a schematic diagram of a manufacturing process of a piezoelectric acoustic sensor according to an embodiment of the present application.
  • FIG. 28 is a schematic diagram of the manufacturing process of another piezoelectric acoustic sensor provided by an embodiment of the present application.
  • 1 anchor unit
  • 2 piezoelectric unit
  • 21 bottom electrode
  • 22 piezoelectric material
  • 221 first piezoelectric material
  • 222 second piezoelectric material
  • 23 upper electrode
  • 24 middle electrode
  • 3 Support unit
  • 4 Hollow structure
  • 5 Back cavity
  • 6 Groove
  • 7 Sacrificial layer.
  • a microphone is an acoustic-electric energy conversion device that converts acoustic signals into electrical signals.
  • Microphones are widely used. From mobile phones, noise-reducing headsets, wireless Bluetooth headsets to smart speakers, microphones penetrate into all aspects of people's lives. The following uses mobile phones and smart speakers as examples to introduce the application of microphones.
  • the phone can also be equipped with other microphones.
  • a microphone can be arranged next to the rear camera so that it can more easily receive sounds from different directions when recording video through the rear camera.
  • the smart speaker After experiencing the independent remote control, the mobile phone's own remote control, and the third-party remote control, the smart speaker finally ushered in the voice control method.
  • the smart speaker is equipped with a microphone array composed of multiple microphones.
  • the microphone array can achieve functions such as voice enhancement, sound source localization, de-reverberation, and sound source signal extraction (separation), which provides for the implementation of voice control in complex environments It's possible.
  • Piezoelectric microphones ie, piezoelectric MEMS microphones manufactured based on microelectromechanical systems (MEMS) are widely used due to their advantages of miniaturization, mass production, and high performance.
  • the piezoelectric MEMS microphone can be equipped with a piezoelectric acoustic sensor to collect sound.
  • the piezoelectric acoustic sensor has many advantages such as high signal-to-noise ratio, low power consumption, and high sensitivity.
  • the embodiments of the present application provide a piezoelectric acoustic sensor, which increases the design of the hollow structure, which can improve the resonant frequency drift and sensitivity reduction caused by residual stress, and help improve the performance of the piezoelectric acoustic sensor. Performance consistency.
  • the piezoelectric acoustic sensor provided by the embodiments of the application is mainly used in the fields of mobile phones, smart speakers, wireless Bluetooth headsets, noise reduction headsets, notebooks, automobiles, etc., and is used as a pickup device.
  • Piezoelectric acoustic sensors are mainly used to restore human voices or environmental sounds.
  • piezoelectric acoustic sensors can complete the human voice collection during mobile phone calls, and multiple piezoelectric acoustic sensors can form an array to achieve directional sound pickup of smart speakers.
  • FIG. 1 is a schematic diagram of a sound pickup system provided by an embodiment of the present application.
  • the sound pickup system includes a piezoelectric acoustic sensor 100 and an amplifier circuit 101.
  • the piezoelectric acoustic sensor 100 can sense sound and convert the vibrational acoustic signal into an original electrical signal. Since the original electrical signal is weak and cannot be used directly, the original electrical signal is generally amplified by the amplifying circuit 101, and the amplified electrical signal enters the audio system 102 to complete the processing.
  • the sound pickup system may be a closed sound chamber formed by a metal shell 201 and a printed circuit board (PCB)/ceramic board 202 .
  • PCB printed circuit board
  • a piezoelectric acoustic sensor 100 and an amplifier circuit 101 are arranged on the PCB/ceramic board 202.
  • the PCB/ceramic board 202 has a sound inlet 2021 so that sound vibration can be transmitted to the piezoelectric acoustic sensor 100.
  • the piezoelectric acoustic sensor 100 and the amplifying circuit 101 are electrically connected by wires, and the acoustic electrical signal collected by the piezoelectric acoustic sensor 100 can be amplified by the amplifying circuit 101 and then supplied to the audio system 102 for processing.
  • FIG. 4 is specifically a cross-sectional view of the piezoelectric acoustic sensor shown in FIG. 4
  • FIG. 7 is specifically a cross-sectional view of the piezoelectric acoustic sensor shown in FIG. 6. 4-7
  • the piezoelectric acoustic sensor includes an anchor unit 1, a piezoelectric unit 2, a support unit 3, and a hollow structure member 4.
  • a back cavity 5 is formed in the anchor unit 1.
  • the piezoelectric unit 2 is used to convert the acoustic signal entering the back cavity 5 into an electrical signal.
  • the supporting unit 3 covers the anchor unit 1 and the piezoelectric unit 2.
  • the hollow structure 4 is connected between the anchor unit 1 and the piezoelectric unit 2 and is embedded in the supporting unit 3.
  • the anchor unit 1, the piezoelectric unit 2, the support unit 3, and the hollow structure 4 are respectively described below:
  • the anchor unit 1 is used to fix various components in the piezoelectric acoustic sensor, and other components in the piezoelectric acoustic sensor are formed on the anchor unit 1.
  • the anchor unit 1 has a back cavity 5 which is an acoustic hole.
  • the piezoelectric unit 2 is suspended above the back cavity 5 to convert the acoustic signals entering the back cavity 5 into electrical signals.
  • the anchor unit 1 may include a substrate layer 11 and an insulating layer 12, and the insulating layer 12 covers the substrate layer 11.
  • the material of the substrate layer 11 may be silicon, quartz, silicon-on-insulator (SOI), silicon carbide (SiC), and other materials.
  • the material of the insulating layer 12 may be silicon nitride or other dielectric materials.
  • the piezoelectric unit 2 may be a piezoelectric stack film, which may include electrodes and piezoelectric materials.
  • the materials of the electrodes may be molybdenum, titanium, platinum, aluminum, etc., and the piezoelectric materials may be aluminum nitride, scandium aluminum nitride, zirconium titanate, etc. Lead etc.
  • the piezoelectric unit 2 can convert mechanical motion into electrical signals. Specifically, when the acoustic signal causes the piezoelectric material to vibrate, the area where the stress is concentrated in the piezoelectric material will generate a potential difference between the upper and lower electrodes, so that the acoustic signal can be converted into an electrical signal and extracted.
  • the shape of the piezoelectric unit 2 can be set according to actual needs.
  • the piezoelectric unit 2 may be circular.
  • the piezoelectric unit 2 may be polygonal.
  • the piezoelectric unit 2 may be a unimorph, and the piezoelectric unit 2 may include a lower electrode 21, a piezoelectric material 22 and an upper electrode 23.
  • the piezoelectric material 22 is located between the lower electrode 21 and the upper electrode 23.
  • the piezoelectric unit 2 may be a bimorph, and the piezoelectric unit 2 may include a lower electrode 21, a first piezoelectric material 221, and a middle electrode. 24.
  • the first piezoelectric material 221 is located between the lower electrode 21 and the middle electrode 24, and the second piezoelectric material 222 is located between the middle electrode 24 and the upper electrode 23.
  • the supporting unit 3 is used to fix the positions of the anchor unit 1, the hollow structure 4 and the piezoelectric unit 2 to enhance the mechanical strength of the piezoelectric acoustic sensor.
  • the material of the support unit 3 may be polysilicon, silicon nitride, silicon dioxide, or the like.
  • the support unit 3 since the hollow structure 4 is connected between the anchor unit 1 and the piezoelectric unit 2, after the support unit 3 is covered on the anchor unit 1 and the piezoelectric unit 2, the support unit 3 will wrap the hollow structure 4, namely The hollow structure 4 will be embedded in the supporting unit 3. In this way, the supporting unit 3 realizes the fixation of the three positions of the anchor unit 1, the hollow structure 4 and the piezoelectric unit 2.
  • the hollow structure 4 is embedded in the support unit 3, that is, the support unit 3 will fill the hollow gap in the hollow structure 4, so that the intrinsic resonance frequency of the piezoelectric acoustic sensor can be adjusted, and the hollow gap can be reduced. Acoustic leakage improves the low-frequency response performance of piezoelectric acoustic sensors.
  • the existence of the supporting unit 3 can make the neutral axis m of the piezoelectric unit 2 far away from the center of the piezoelectric unit 2 (that is, away from the piezoelectric material 22), which can effectively improve the piezoelectric acoustics.
  • the charge output and sensitivity of the sensor can be made to make the neutral axis m of the piezoelectric unit 2 far away from the center of the piezoelectric unit 2 (that is, away from the piezoelectric material 22), which can effectively improve the piezoelectric acoustics.
  • the piezoelectric unit 2 is a bimorph, and the upper surface of the piezoelectric unit 2 is partially covered with the supporting unit 3.
  • the edge portion of the upper surface of the piezoelectric unit 2 is covered with the support unit 3, and the center portion of the upper surface of the piezoelectric unit 2 is not covered with the support unit 3, that is, the part of the support unit 3 located above the piezoelectric unit 2
  • the central area is hollowed out.
  • the neutral axis m of the piezoelectric unit 2 is located in the middle electrode 24 of the piezoelectric unit 2, so as not to affect the charge output and sensitivity of the piezoelectric acoustic sensor.
  • the hollow structure 4 is a mechanical structure that removes part of the material, and has the characteristics of low rigidity and easy deformation.
  • the shape of the hollow structure 4 may be bent, the width w1 of the bent portion of the bent hollow structure 4 may be 1 to 10 microns, and the width of the gap between the bent portions w2 can be greater than 0.5 microns.
  • the shape of the hollow structure 4 may be a circular shape, the width w3 of the circular portion of the hollow structure 4 of the circular shape may be 1 to 10 micrometers, and the width w4 of the hollow area may be greater than 2 micrometers.
  • the shape of the hollow structure member 4 may be a grid shape, and the width w5 of the hollow area of the mesh-shaped hollow structure member 4 may be greater than 1 micron.
  • the hollow structure 4 is connected between the anchor unit 1 and the piezoelectric unit 2. That is, the first end of the hollow structure member 4 may be fixed on the upper surface of the anchor unit 1 (that is, the upper surface of the insulating layer 12 ), and the second end of the hollow structure member 4 may be connected to the piezoelectric unit 2.
  • the hollow structure 4 can play a role in stress relief.
  • the number of hollow structural members 4 can be set according to the requirements of use. In order to improve the stress release effect, the number of hollow structural members 4 may be greater than or equal to two.
  • the at least two hollow structure members 4 can also be evenly distributed around the piezoelectric unit 2. For example, as shown in FIG. 15, the number of hollow structure members 4 may be two, and the two hollow structure members 4 may be evenly distributed around the piezoelectric unit 2. Alternatively, as shown in FIG. 16, the number of hollow structure members 4 may be three, and the three hollow structure members 4 may be evenly distributed around the piezoelectric unit 2. Alternatively, as shown in FIG. 17, the number of hollow structure members 4 may be 8, and the eight hollow structure members 4 may be evenly distributed around the piezoelectric unit 2.
  • the hollow structure member 4 can be connected to at least one of the electrode in the piezoelectric unit 2 and the piezoelectric material.
  • the hollow structure 4 and the connected electrodes may be made of the same material.
  • the hollow structure 4 and the piezoelectric material to which it is connected may use the same material.
  • the hollow structure 4 When the hollow structure 4 is connected to the electrodes and piezoelectric materials in the piezoelectric unit 2, that is, when a part of the hollow structure 4 is connected to the electrodes in the piezoelectric unit 2 and the other part is connected to the piezoelectric unit 2
  • a part of the hollow structure 4 and the connected electrode may use the same material
  • the other part of the hollow structure 4 may use the same material as the connected piezoelectric material.
  • the hollow structure 4 can be a multi-layer structure, each layer in the hollow structure 4 can be connected to an electrode or piezoelectric material, and each layer and the electrode or piezoelectric material to which it is connected use the same material .
  • the hollow structural member 4 connected to the electrode or piezoelectric material can be manufactured while manufacturing the electrode or piezoelectric material in the piezoelectric unit 2, thereby simplifying the manufacturing process, saving manufacturing cost and manufacturing time.
  • the hollow The structural member 4 can be connected to any one of these three parts.
  • the number of hollow structure members 4 is greater than or equal to 2
  • at least two hollow structure members 4 can be connected to one part of the piezoelectric unit 2, or each hollow structure member 4 can be respectively connected to different parts of the piezoelectric unit 2. part.
  • At least two hollow structure members 4 are both connected to the lower electrode 21 in the piezoelectric unit 2.
  • at least one of the at least two hollow structure members 4 is connected to the upper electrode 23 in the piezoelectric unit 2, and the other hollow structure members 4 are connected to the lower electrode 21 in the piezoelectric unit 2.
  • the piezoelectric unit 2 shown in FIG. 6, FIG. 7 or FIG. 9 that is, the piezoelectric unit 2 includes a bottom electrode 21, a first piezoelectric material 221, a middle electrode 24, and a second
  • the hollow structure 4 can be connected to any part of these five parts.
  • the number of hollow structure members 4 is greater than or equal to 2
  • at least two hollow structure members 4 can be connected to one part of the piezoelectric unit 2, or each hollow structure member 4 can be respectively connected to different parts of the piezoelectric unit 2. part.
  • At least two hollow structure members 4 are both connected to the lower electrode 21 in the piezoelectric unit 2.
  • at least one of the at least two hollow structure members 4 is connected to the middle electrode 24 in the piezoelectric unit 2, and the other hollow structure members 4 are connected to the lower electrode 21 in the piezoelectric unit 2.
  • at least one of the at least two hollow structure members 4 is connected to the upper electrode 23 in the piezoelectric unit 2, and the other hollow structure members 4 are connected to the lower electrode 21 in the piezoelectric unit 2.
  • at least two hollow structural members 4 are both connected to the middle electrode 24 in the piezoelectric unit 2.
  • FIG. 19 at least two hollow structure members 4 are both connected to the middle electrode 24 in the piezoelectric unit 2.
  • At least two hollow structure members 4 are both connected to the upper electrode 23 in the piezoelectric unit 2.
  • at least one of the at least two hollow structure members 4 is connected to the upper electrode 23 in the piezoelectric unit 2, and the other hollow structure members 4 are connected to the middle electrode 24 in the piezoelectric unit 2.
  • the sacrificial layer 7 is often formed first, then the piezoelectric unit 2 is formed on the sacrificial layer 7, and then the sacrificial layer 7 is removed.
  • the hollow structure 4 can serve as a mechanical connection.
  • the piezoelectric unit 2 can be connected to the anchor unit 1 through the hollow structure 4 Therefore, it is possible to prevent the piezoelectric unit 2 from falling off during the removal of the sacrificial layer 7.
  • the hollow structure 4 can play the role of stress relief.
  • the hollow structure 4 with low rigidity and easy deformation allows the piezoelectric unit 2 to change through the hollow gap.
  • the residual stress of the piezoelectric unit 2 is released through the deformable hollow structure 4, so as to achieve zero residual stress. Since the residual stress of the piezoelectric unit 2 has been released, the piezoelectric acoustic sensor of the same geometric size has a consistent resonance frequency and sensitivity.
  • the piezoelectric acoustic sensor includes an anchor unit 1, a piezoelectric unit 2, a support unit 3 and a hollow structure 4.
  • a back cavity 5 is formed in the anchor unit 1.
  • the piezoelectric unit 2 is used to convert the acoustic signal entering the back cavity 5 into an electrical signal.
  • the supporting unit 3 covers the anchor unit 1 and the piezoelectric unit 2.
  • the hollow structure 4 is connected between the anchor unit 1 and the piezoelectric unit 2 and is embedded in the supporting unit 3.
  • the residual stress of the piezoelectric unit 2 can be released by the deformable hollow structure 4 during the manufacturing process to achieve zero residual stress, thereby avoiding the resonant frequency drift of the piezoelectric acoustic sensor, and avoiding the sensitivity reduction of the piezoelectric acoustic sensor, and then Helps improve the performance consistency of piezoelectric acoustic sensors.
  • Fig. 26 is a flowchart of a method for manufacturing the piezoelectric acoustic sensor shown in Figs. 4 to 25 according to an embodiment of the present application. Referring to Figure 26, the method includes:
  • Step 2601 Provide an anchor unit, and etch a groove on the upper surface of the anchor unit.
  • an anchor unit 1 is provided, and then a groove 6 is etched on the upper surface of the anchor unit 1.
  • the anchor unit 1 is used to fix various components in the piezoelectric acoustic sensor, and other components in the piezoelectric acoustic sensor may be formed on the anchor unit 1.
  • the anchor unit 1 may include a substrate layer 11 and an insulating layer 12.
  • a substrate layer 11 may be provided first, and then an insulating layer 12 is formed on the substrate layer 11.
  • the material of the substrate layer 11 may be silicon, quartz, SOI, SiC and other materials.
  • the material of the insulating layer 12 may be silicon nitride or other dielectric materials.
  • forming the insulating layer 12 on the substrate layer 11 may be to deposit a material for forming the insulating layer 12 on the upper surface of the substrate layer 11 to obtain the insulating layer 12.
  • the shape and position of the groove 6 may be defined on the upper surface of the insulating layer 12 to determine the area where the groove 6 is located on the upper surface of the insulating layer 12. After that, the other areas of the upper surface of the insulating layer 12 except for the area where the groove 6 are located are protected by a protective glue, and then the upper surface of the insulating layer 12 is etched to obtain the recesses in the upper surface of the insulating layer 12 Slot 6.
  • the shape and position of the groove 6 can be defined by a photolithography process, for example, it can be defined by a photolithography process such as electron beam exposure and optical exposure.
  • the protective glue may be an anti-etching glue, poly (methyl methacrylate) (PMMA), or the like.
  • the upper surface of the insulating layer 12 when etched, it may be etched by processes such as reactive ion etching (RIE) and oxygen plasma etching.
  • RIE reactive ion etching
  • oxygen plasma etching oxygen plasma etching
  • Step 2602 Fill the sacrificial layer in the groove.
  • the sacrificial layer 7 is filled in the groove 6 in the upper surface of the anchor unit 1.
  • the sacrificial layer 7 can be deposited in the groove 6 in the upper surface of the anchor unit 1.
  • the material forming the sacrificial layer 7 results in the sacrificial layer 7.
  • the material of the sacrificial layer 7 may be silicon dioxide, phosphorus-doped silicon oxide, and other materials that are easily corroded by chemical etching agents.
  • Step 2603 forming a piezoelectric unit on the sacrificial layer, and forming a hollow structure on the anchor unit and the sacrificial layer.
  • the piezoelectric unit 2 is formed on the sacrificial layer 7, and the hollow structure 4 is formed on the anchor unit 1 and the sacrificial layer 7.
  • the piezoelectric unit 2 may be a piezoelectric stacked film, which may include electrodes and piezoelectric materials.
  • the materials of the electrodes may be molybdenum, titanium, platinum, aluminum, etc., and the piezoelectric materials may be aluminum nitride or scandium nitride. Aluminum, lead zirconate titanate, etc.
  • the piezoelectric unit 2 can convert mechanical motion into electrical signals. Specifically, when the acoustic signal causes the piezoelectric material to vibrate, the area where the stress is concentrated in the piezoelectric material will generate a potential difference between the upper and lower electrodes, so that the acoustic signal can be converted into an electrical signal and extracted.
  • the area of the lower surface of the piezoelectric unit 2 is smaller than the area of the upper surface of the sacrificial layer 7, that is, the piezoelectric unit 2 is completely located on the upper surface of the sacrificial layer 7.
  • the shape and position of the piezoelectric unit 2 can be defined on the upper surface of the sacrificial layer 7 to determine the area where the piezoelectric unit 2 is located on the upper surface of the sacrificial layer 7. After that, the material for forming the piezoelectric unit 2 is deposited on the area where the piezoelectric unit 2 is located on the upper surface of the sacrificial layer 7 to obtain the piezoelectric unit 2.
  • the shape and position of the piezoelectric unit 2 can be defined by a photolithography process, for example, it can be defined by a photolithography process such as electron beam exposure and optical exposure.
  • the piezoelectric unit 2 may be a unimorph, and the piezoelectric unit 2 may include a lower electrode 21, a piezoelectric material 22 and an upper electrode 23.
  • the piezoelectric unit 2 when the piezoelectric unit 2 is formed on the sacrificial layer 7, the lower electrode 21 may be formed on the sacrificial layer 7, the piezoelectric material 22 may be formed on the lower electrode 21, and the upper electrode may be formed on the piezoelectric material 22. ⁇ 23 ⁇ Electrode 23.
  • the material for forming the lower electrode 21 can be deposited on the upper surface of the sacrificial layer 7 to obtain the lower electrode 21, and then the piezoelectric material 22 can be deposited on the upper surface of the lower electrode 21, and finally on the upper surface of the piezoelectric material 22
  • the upper electrode 23 is obtained by depositing a material for forming the upper electrode 23 on the upper electrode.
  • the piezoelectric unit 2 may be a bimorph, and the piezoelectric unit 2 may include a bottom electrode 21, a first piezoelectric material 221, a middle electrode 24, and a second piezoelectric material. Material 222 and upper electrode 23.
  • the piezoelectric unit 2 when the piezoelectric unit 2 is formed on the sacrificial layer 7, the lower electrode 21 may be formed on the sacrificial layer 7, the first piezoelectric material 221 may be formed on the lower electrode 21, and the first piezoelectric material 221 may be formed on the lower electrode 21.
  • a middle electrode 24 is formed thereon, a second piezoelectric material 222 is formed on the middle electrode 24, and an upper electrode 23 is formed on the second piezoelectric material 222.
  • the material for forming the lower electrode 21 may be deposited on the upper surface of the sacrificial layer 7 to obtain the lower electrode 21, and then the first piezoelectric material 221 may be deposited on the upper surface of the lower electrode 21, and the first piezoelectric material 221 may be deposited on the upper surface of the lower electrode 21.
  • the material used to form the middle electrode 24 is deposited on the upper surface of the middle electrode 24 to obtain the middle electrode 24, and then the second piezoelectric material 222 is deposited on the upper surface of the middle electrode 24, and the upper surface of the second piezoelectric material 222 is deposited for forming
  • the material of the upper electrode 23 results in the upper electrode 23.
  • the hollow structure 4 is a mechanical structure with a part of material removed, and has the characteristics of low rigidity and easy deformation.
  • the shape of the hollow structure 4 can be set according to the use requirements.
  • the shape of the hollow structure 4 can be a bent shape, a back shape, a grid shape, and the like.
  • the hollow structure 4 is connected between the anchor unit 1 and the piezoelectric unit 2. That is, the first end of the hollow structure member 4 may be fixed on the upper surface of the anchor unit 1 (that is, the upper surface of the insulating layer 12 ), and the second end of the hollow structure member 4 may be connected to the piezoelectric unit 2.
  • the hollow structure 4 can play a stress relief function.
  • the number of hollow structural members 4 can be set according to the requirements of use. In order to improve the stress release effect, the number of hollow structural members 4 may be greater than or equal to two. Further, the at least two hollow structure members 4 can also be evenly distributed around the piezoelectric unit 2.
  • the hollow structure member 4 can be connected to at least one of the electrode in the piezoelectric unit 2 and the piezoelectric material.
  • the hollow structure 4 and the connected electrodes may be made of the same material.
  • the hollow structure 4 and the piezoelectric material to which it is connected may use the same material.
  • the hollow structure 4 When the hollow structure 4 is connected to the electrodes and piezoelectric materials in the piezoelectric unit 2, that is, when a part of the hollow structure 4 is connected to the electrodes in the piezoelectric unit 2 and the other part is connected to the piezoelectric unit 2
  • a part of the hollow structure 4 and the connected electrode may use the same material
  • the other part of the hollow structure 4 may use the same material as the connected piezoelectric material.
  • the hollow structure 4 can be a multi-layer structure, each layer in the hollow structure 4 can be connected to an electrode or piezoelectric material, and each layer and the electrode or piezoelectric material to which it is connected use the same material .
  • the hollow structural member 4 connected to the electrode or piezoelectric material can be manufactured while manufacturing the electrode or piezoelectric material in the piezoelectric unit 2, thereby simplifying the manufacturing process, saving manufacturing cost and manufacturing time.
  • the hollow structure 4 can be connected with this Connect any of the three parts.
  • the number of hollow structure members 4 is greater than or equal to 2
  • at least two hollow structure members 4 can be connected to one part of the piezoelectric unit 2, or each hollow structure member 4 can be respectively connected to different parts of the piezoelectric unit 2. part.
  • At least two hollow structure members 4 are both connected to the lower electrode 21 in the piezoelectric unit 2.
  • at least one of the at least two hollow structure members 4 is connected to the upper electrode 23 in the piezoelectric unit 2, and the other hollow structure members 4 are connected to the lower electrode 21 in the piezoelectric unit 2.
  • the piezoelectric unit 2 shown in FIG. 28 includes a lower electrode 21, a first piezoelectric material 221, a middle electrode 24, a second piezoelectric material 222, and an upper electrode.
  • the hollow structure 4 can be connected to any part of the five parts.
  • the number of hollow structure members 4 is greater than or equal to 2
  • at least two hollow structure members 4 can be connected to one part of the piezoelectric unit 2, or each hollow structure member 4 can be respectively connected to different parts of the piezoelectric unit 2. part.
  • At least two hollow structure members 4 are both connected to the lower electrode 21 in the piezoelectric unit 2.
  • at least one of the at least two hollow structure members 4 is connected to the middle electrode 24 in the piezoelectric unit 2, and the other hollow structure members 4 are connected to the lower electrode 21 in the piezoelectric unit 2.
  • at least one of the at least two hollow structure members 4 is connected to the upper electrode 23 in the piezoelectric unit 2, and the other hollow structure members 4 are connected to the lower electrode 21 in the piezoelectric unit 2.
  • at least two hollow structural members 4 are both connected to the middle electrode 24 in the piezoelectric unit 2.
  • at least two hollow structure members 4 are both connected to the upper electrode 23 in the piezoelectric unit 2.
  • at least one of the at least two hollow structure members 4 is connected to the upper electrode 23 in the piezoelectric unit 2, and the other hollow structure members 4 are connected to the middle electrode 24 in the piezoelectric unit 2.
  • the shape and position of the hollow structure 4 can be defined on the upper surface of the anchor unit 1 and the upper surface of the sacrificial layer 7 to determine the anchoring order.
  • the upper surface of the element 1 and the upper surface of the sacrificial layer 7 are in the area where the hollow structure 4 is located.
  • the material for forming the hollow structure 4 is deposited on the area where the hollow structure 4 is located to obtain the hollow structure 4.
  • the shape and position of the hollow structure 4 can be defined by a photolithography process, for example, it can be defined by a photolithography process such as electron beam exposure and optical exposure.
  • Step 2604 Remove the sacrificial layer.
  • the sacrificial layer 7 may be removed.
  • a chemical etchant can generally be used to etch the sacrificial layer 7 away.
  • the material of the sacrificial layer 7 is silicon dioxide
  • liquid hydrofluoric acid may be used to etch the silicon dioxide to remove the silicon dioxide.
  • the hollow structure 4 can serve as a mechanical connection.
  • the piezoelectric unit 2 can be connected to the anchor unit 1 through the hollow structure 4 Therefore, the piezoelectric unit 2 can be prevented from falling off during the removal of the sacrificial layer 7.
  • the piezoelectric unit 2 can be suspended above the groove 6 through the hollow structure 4.
  • the hollow structure 4 can play the role of stress relief.
  • the hollow structure 4 with low rigidity and easy deformation allows the piezoelectric unit 2 to change through the hollow gap.
  • the residual stress of the piezoelectric unit 2 is released through the deformable hollow structure 4, so as to achieve zero residual stress. Since the residual stress of the piezoelectric unit 2 has been released, the finally manufactured piezoelectric acoustic sensor of the same geometric size has a consistent resonance frequency and sensitivity.
  • the piezoelectric unit 2 Since the piezoelectric unit 2 was completely located on the sacrificial layer 7 before, after the sacrificial layer 7 is removed, when the residual stress of the piezoelectric unit 2 is released and the various devices (including the anchor unit 1, the piezoelectric unit 2 and the hollow structure) 4) After drying, the piezoelectric unit 2 will drop into the groove 6 where the sacrificial layer 7 was originally located under the action of gravity and contact the groove bottom of the groove 6. That is, when the residual stress of the piezoelectric unit 2 is released and the various devices are dried, the piezoelectric unit 2 will be attached to the surface of the anchor unit 1.
  • Step 2605 When the piezoelectric unit contacts the bottom of the groove, a support unit is formed on the anchor unit and the piezoelectric unit, and the support unit is wrapped outside the hollow structure.
  • a support unit 3 can be formed on the anchor unit 1 and the piezoelectric unit 2. At this time, the support unit 3 It will be wrapped outside the hollow structure 4.
  • the support unit 3 is used to fix the positions of the anchor unit 1, the hollow structure 4 and the piezoelectric unit 2 to enhance the mechanical strength of the finally manufactured piezoelectric acoustic sensor.
  • the material of the support unit 3 may be polysilicon, silicon nitride, silicon dioxide, or the like.
  • the support unit 3 since the hollow structure 4 is connected between the anchor unit 1 and the piezoelectric unit 2, after the support unit 3 is formed on the anchor unit 1 and the piezoelectric unit 2, the support unit 3 will wrap the outside of the hollow structure 4 .
  • the supporting unit 3 covers the anchoring unit 1 and the piezoelectric unit 2, and the hollow structure 4 is embedded in the supporting unit 3. In this way, the supporting unit 3 realizes the alignment of the anchoring unit 1, the hollow structure 4 and the piezoelectric unit 2 are fixed in position.
  • the support unit 3 will be wrapped outside the hollow structure 4, that is, the support unit 3 will fill the hollow gap in the hollow structure 4, so that the intrinsic resonance frequency of the finally manufactured piezoelectric acoustic sensor can be adjusted and reduced
  • the sound leakage caused by the hollow gap improves the low-frequency response performance of the piezoelectric acoustic sensor.
  • the piezoelectric unit 2 shown in FIG. 27 that is, when the piezoelectric unit 2 includes the lower electrode 21, the piezoelectric material 22, and the upper electrode 23, it can be directly on the upper surface of the anchor unit 1.
  • the support unit 3 is deposited on the upper surface of the piezoelectric unit 2 and the deposited support unit 3 will wrap the hollow structure 4.
  • the upper surface of the piezoelectric unit 2 is entirely covered with the supporting unit 3.
  • the existence of the support unit 3 can make the neutral axis of the piezoelectric unit 2 far away from the center of the piezoelectric unit 2 (that is, away from the piezoelectric material 22), which can effectively improve the charge output and sensitivity of the finally manufactured piezoelectric acoustic sensor .
  • the shape and position of the support unit 3 can be defined on the upper surface of the anchor unit 1 and the upper surface of the piezoelectric unit 2.
  • the material for forming the support unit 3 is deposited on the area where the support unit 3 is located to obtain the support unit 3.
  • the shape and position of the supporting unit 3 can be defined by a photolithography process, for example, it can be defined by a photolithography process such as electron beam exposure and optical exposure.
  • the piezoelectric unit 2 shown in FIG. 28 includes a lower electrode 21, a first piezoelectric material 221, a middle electrode 24, a second piezoelectric material 222, and an upper electrode.
  • the support unit 3 can be deposited on the upper surface of the anchor unit 1 and the upper surface of the piezoelectric unit 2, and the deposited support unit 3 will wrap the hollow structure 4, and then remove the support unit 3 and deposit on the upper surface of the piezoelectric unit 2. At least a part of the upper surface of the piezoelectric unit 2.
  • the upper surface of the piezoelectric unit 2 is partially covered with the support unit 3.
  • a part of the support unit 3 deposited on the center of the upper surface of the piezoelectric unit 2 can be removed.
  • the edge of the upper surface of the piezoelectric unit 2 is covered with the support unit 3, and the upper surface of the piezoelectric unit 2
  • the central part is not covered with the supporting unit 3, that is, the central area of the part of the supporting unit 3 located above the piezoelectric unit 2 is hollowed out.
  • the neutral axis of the piezoelectric unit 2 is located in the middle electrode 24 of the piezoelectric unit 2 so as not to affect the charge output and sensitivity of the finally manufactured piezoelectric acoustic sensor.
  • the shape and position of the target part can be defined on the upper surface of the support unit 3 to determine the target part on the upper surface of the support unit 3.
  • the target part is at least a part deposited on the upper surface of the piezoelectric unit 2.
  • the shape and position of the target part can be defined by a photolithography process, for example, it can be defined by a photolithography process such as electron beam exposure and optical exposure.
  • the etching may be performed by processes such as reactive ion etching, oxygen plasma etching, and the like.
  • Step 2606 etch the back cavity at the position between the bottom of the groove and the lower surface of the anchor unit.
  • the back cavity 5 is etched at the position between the bottom of the groove 6 and the lower surface of the anchor unit 1.
  • the back cavity 5 is a sound inlet.
  • the piezoelectric unit 2 is suspended above the sound inlet and can sense sound.
  • an anchor unit is provided, a groove is etched on the upper surface of the anchor unit, and then the sacrificial layer is filled in the groove.
  • a piezoelectric unit is formed on the sacrificial layer, and a hollow structure is formed on the anchor unit and the sacrificial layer, and the hollow structure is connected between the anchor unit and the piezoelectric unit. After that, the sacrificial layer is removed.
  • a support unit is formed on the anchor unit and the piezoelectric unit, and the support unit is wrapped outside the hollow structure.
  • the back cavity is etched at the position between the bottom of the groove and the lower surface of the anchor unit to obtain a piezoelectric acoustic sensor.
  • the residual stress of the piezoelectric unit can be released by the deformable hollow structure to achieve zero residual stress, thus avoiding the resonant frequency drift of the piezoelectric acoustic sensor, and avoiding the sensitivity reduction of the piezoelectric acoustic sensor, and then Helps improve the performance consistency of piezoelectric acoustic sensors.

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Abstract

本申请公开了一种压电声学传感器及其制造方法，属于电子技术领域。该压电声学传感器包括：锚定单元、压电单元、支撑单元和镂空结构件。锚定单元中形成有背腔。压电单元用于将进入该背腔的声信号转为电信号。支撑单元覆盖于锚定单元和压电单元上。镂空结构件连接于锚定单元与压电单元之间，且内嵌于支撑单元中。本申请中的压电单元的残余应力在制造过程中可以通过可形变的镂空结构件释放，实现零残余应力，因而可以避免压电声学传感器的谐振频率漂移，以及避免压电声学传感器的灵敏度下降，进而有助于提高压电声学传感器的性能一致性。

Description

压电声学传感器及其制造方法
本申请要求于2020年4月29日提交中国国家知识产权局、申请号为202010357080.1、发明名称为“压电声学传感器及其制造方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及电子技术领域，特别涉及一种压电声学传感器及其制造方法。
背景技术
随着电子技术的发展，麦克风已深入到人们生活的方方面面，其广泛应用于手机、智能音箱、无线蓝牙耳机、降噪耳麦、笔记本、汽车等领域。麦克风中可以设置压电声学传感器来采集声音，压电声学传感器具有高信噪比、低功耗、高灵敏度等诸多优点。
压电声学传感器包括电极和压电材料。当声信号引起压电材料振动时，压电材料中应力集中的区域会在其上下电极之间产生电势差，这样就可以将声信号转化为电信号提取出来。
目前，压电声学传感器采用悬臂梁结构，悬臂梁受到声压压迫后会发生弯曲，其弯曲应力会产生电信号。然而，因制造工艺的影响，悬臂梁中会存在残余应力，这会导致悬臂梁发生翘曲，如此会增大悬臂梁的间隙，导致压电声学传感器的声漏增大，从而对压电声学传感器的谐振频率和灵敏度造成影响。
发明内容
本申请提供了一种压电声学传感器及其制造方法，有助于提升压电声学传感器的谐振频率和灵敏度的一致性。
一方面，提供了一种压电声学传感器，压电声学传感器包括：锚定单元、压电单元、支撑单元和镂空结构件。锚定单元中形成有背腔。压电单元用于将进入该背腔的声信号转为电信号。支撑单元覆盖于锚定单元和压电单元上。镂空结构件连接于锚定单元与压电单元之间，且内嵌于支撑单元中。
锚定单元用于固定压电声学传感器中的各个组件，压电声学传感器中的其它组件均是在锚定单元上形成。锚定单元具有背腔，该背腔为进声孔，压电单元悬浮在该背腔上方来感知声音。可选地，锚定单元包括衬底层和绝缘层，绝缘层覆盖于衬底层上。
压电单元可以是压电堆叠薄膜，可以包括电极和压电材料。压电单元可以将机械运动转化为电信号。具体地，当声信号引起压电材料振动时，压电材料中应力集中的区域会其上下电极之间产生电势差，这样就可以将声信号转化为电信号提取出来。
支撑单元用于固定锚定单元、镂空结构件和压电单元的位置，以增强压电声学传感器的机械强度。由于镂空结构件连接在锚定单元与压电单元之间，所以支撑单元覆盖于锚定单元和压电单元上后，支撑单元会包裹镂空结构件，即镂空结构件会内嵌于支撑单元中。这种情 况下，支撑单元会填充镂空结构件中的镂空间隙，如此可以调整压电声学传感器的本征谐振频率，减小镂空间隙造成的声漏，提升压电声学传感器的低频响应性能。
镂空结构件为去除部分材料的机械结构，具有低刚度、易形变的特性。例如，镂空结构件的形状可以为弯折状、回形状、或网格状等。镂空结构件可以起到应力释放作用。为了提升应力释放效果，镂空结构件的数量可以大于或等于2。进一步地，至少两个镂空结构件还可以均匀分布在压电单元周围。
一种可能的方式中，压电单元可以是单压电晶片，压电单元可以包括下电极、压电材料和上电极，压电材料位于下电极与上电极之间。压电单元的上表面全部覆盖有支撑单元。如此，支撑单元的存在可以使得压电单元的中性轴远离压电单元的中心(即远离压电材料)，从而可以有效提升压电声学传感器的电荷输出和灵敏度。
另一种可能的方式中，压电单元可以是双压电晶片，压电单元可以包括下电极、第一压电材料、中电极、第二压电材料和上电极。第一压电材料位于下电极与中电极之间，第二压电材料位于中电极与上电极之间。压电单元的上表面部分覆盖有支撑单元。如此，可以保证压电单元的中性轴位于压电单元的中电极中，从而不会影响压电声学传感器的电荷输出和灵敏度。
可选地，镂空结构件可以与压电单元中的电极和压电材料中的至少一个连接。并且，当镂空结构件与压电单元中的电极连接时，镂空结构件可以与其所连接的电极采用同一种材料。当镂空结构件与压电单元中的压电材料连接时，镂空结构件可以与其所连接的压电材料采用同一种材料。当镂空结构件分别与压电单元中的电极和压电材料连接时，也即是当镂空结构件中的一部分与压电单元中的电极连接且另一部分与压电单元中的压电材料连接时，镂空结构件中的一部分可以与所连接的电极采用同一种材料，镂空结构件中的另一部分可以与所连接的压电材料采用同一种材料。这种情况下，镂空结构件可以是多层结构，镂空结构件中的每一层可以与电极或压电材料连接，且每一层与其所连接的电极或压电材料采用同一种材料。
如此，在制造压电单元中的电极或压电材料的同时可以制造与其所连接的镂空结构件，从而简化了制造工艺，节省了制造成本和制造时间。
在本申请中，在压电声学传感器的制造过程中，往往是先形成牺牲层，再在牺牲层之上形成压电单元，然后再去除牺牲层。这种情况下，一方面，镂空结构件可以起到机械连接作用，在去除压电单元下方的牺牲层的过程中，压电单元可以通过镂空结构件与锚定单元连接，从而可以避免压电单元在牺牲层的去除过程中脱落。另一方面，镂空结构件可以起到应力释放作用，在去除压电单元下方的牺牲层的过程中，低刚度、易形变的镂空结构件通过镂空间隙的变化允许压电单元进行活动(如上下弯曲或水平伸缩)，压电单元的残余应力通过可形变的镂空结构件释放，实现零残余应力。由于压电单元的残余应力已经释放，因此相同几何尺寸的压电声学传感器具有一致的谐振频率和灵敏度。
一方面，提供了一种压电声学传感器的制造方法。在该方法中，提供一锚定单元，在锚定单元的上表面刻蚀凹槽，然后在该凹槽内填充牺牲层。在牺牲层之上形成压电单元，以及在锚定单元和牺牲层之上形成镂空结构件，压电单元的下表面的面积小于牺牲层的上表面的面积，镂空结构件连接在锚定单元与压电单元之间。之后，去除牺牲层。当压电单元与凹槽的槽底接触时，在锚定单元和压电单元之上形成支撑单元，支撑单元包裹在镂空结构件外。 最后，在该凹槽的槽底与锚定单元的下表面之间的部位刻蚀背腔，得到压电声学传感器。
锚定单元用于固定压电声学传感器中的各个组件，压电声学传感器中的其它组件可以在锚定单元上形成。其中，锚定单元可以包括衬底层和绝缘层。这种情况下，提供一锚定单元时，可以先提供一衬底层，再在衬底层之上形成绝缘层。
压电单元可以是压电堆叠薄膜，可以包括电极和压电材料。压电单元可以将机械运动转化为电信号。具体地，当声信号引起压电材料振动时，压电材料中应力集中的区域会其上下电极之间产生电势差，这样就可以将声信号转化为电信号提取出来。压电单元的下表面的面积小于牺牲层的上表面的面积，也即是，压电单元完全位于牺牲层的上表面上。
镂空结构件为去除部分材料的机械结构，具有低刚度、易形变的特性。例如，镂空结构件的形状可以是弯折状、回形状、或网格状等。镂空结构件可以起到应力释放作用。为了提升应力释放效果，镂空结构件的数量可以大于或等于2。进一步地，至少两个镂空结构件还可以均匀分布在压电单元周围。
支撑单元用于固定锚定单元、镂空结构件和压电单元的位置，以增强压电声学传感器的机械强度。由于镂空结构件连接在锚定单元与压电单元之间，所以在锚定单元和压电单元之上形成支撑单元之后，支撑单元会包裹镂空结构件外。也就是说，支撑单元覆盖于锚定单元和压电单元上，而镂空结构件内嵌于支撑单元中。如此，支撑单元会填充镂空结构件中的镂空间隙，如此可以调整最终制造出的压电声学传感器的本征谐振频率，减小镂空间隙造成的声漏，提升压电声学传感器的低频响应性能。
一种可能的方式中，压电单元可以是单压电晶片，压电单元可以包括下电极、压电材料和上电极。这种情况下，在牺牲层之上形成压电单元时，可以在牺牲层之上形成下电极，在下电极之上形成压电材料，在压电材料之上形成上电极。在锚定单元和压电单元之上形成支撑单元时，可以直接在锚定单元的上表面和压电单元的上表面沉积支撑单元，所沉积的支撑单元将会包裹镂空结构件。
这种方式中，压电单元的上表面上全部覆盖有支撑单元。如此，支撑单元的存在可以使得压电单元的中性轴远离压电单元的中心(即远离压电材料)，从而可以有效提升最终制造出的压电声学传感器的电荷输出和灵敏度。
另一种可能的方式中，压电单元可以是双压电晶片，压电单元可以包括下电极、第一压电材料、中电极、第二压电材料和上电极。这种情况下，在牺牲层之上形成压电单元时，可以在牺牲层之上形成下电极，在下电极之上形成第一压电材料，在第一压电材料之上形成中电极，在中电极之上形成第二压电材料，在第二压电材料之上形成上电极。在锚定单元和压电单元之上形成支撑单元时，可以先在锚定单元的上表面和压电单元的上表面沉积支撑单元，所沉积的支撑单元将会包裹镂空结构件，然后再去除支撑单元中沉积在压电单元的上表面上的至少一部分。
这种方式中，压电单元的上表面部分覆盖有支撑单元，如此可以保证压电单元的中性轴位于压电单元的中电极中，从而不会影响最终制造出的压电声学传感器的电荷输出和灵敏度。
可选地，镂空结构件可以与压电单元中的电极和压电材料中的至少一个连接。并且，当镂空结构件与压电单元中的电极连接时，镂空结构件可以与其所连接的电极采用同一种材料。当镂空结构件与压电单元中的压电材料连接时，镂空结构件可以与其所连接的压电材料采用同一种材料。当镂空结构件分别与压电单元中的电极和压电材料连接时，也即是当镂空结构 件中的一部分与压电单元中的电极连接且另一部分与压电单元中的压电材料连接时，镂空结构件中的一部分可以与所连接的电极采用同一种材料，镂空结构件中的另一部分可以与所连接的压电材料采用同一种材料。这种情况下，镂空结构件可以是多层结构，镂空结构件中的每一层可以与电极或压电材料连接，且每一层与其所连接的电极或压电材料采用同一种材料。
如此，在制造压电单元中的电极或压电材料的同时可以制造与其所连接的镂空结构件，从而简化了制造工艺，节省了制造成本和制造时间。
在本申请中，一方面，镂空结构件可以起到机械连接作用，在去除压电单元下方的牺牲层的过程中，压电单元可以通过镂空结构件与锚定单元连接，从而可以避免压电单元在牺牲层的去除过程中脱落，此时压电单元可以通过镂空结构件悬浮在凹槽的上方。另一方面，镂空结构件可以起到应力释放作用，在去除压电单元下方的牺牲层的过程中，低刚度、易形变的镂空结构件通过镂空间隙的变化允许压电单元进行活动(如上下弯曲或水平伸缩)，压电单元的残余应力通过可形变的镂空结构件释放，实现零残余应力。由于压电单元的残余应力已经释放，因此最终制造出的相同几何尺寸的压电声学传感器具有一致的谐振频率和灵敏度。
本申请提供的技术方案至少可以带来以下有益效果：
压电声学传感器包括锚定单元、压电单元、支撑单元和镂空结构件。锚定单元中形成有背腔。压电单元用于将进入背腔的声信号转为电信号。支撑单元覆盖于锚定单元和压电单元上。镂空结构件连接于锚定单元与压电单元之间，且内嵌于支撑单元中。压电单元的残余应力在制造过程中可以通过可形变的镂空结构件释放，实现零残余应力，因而可以避免压电声学传感器的谐振频率漂移，以及避免压电声学传感器的灵敏度下降，进而有助于提高压电声学传感器的性能一致性。
附图说明
图1是本申请实施例提供的一种拾音系统的示意图；
图2是本申请实施例提供的另一种拾音系统的示意图；
图3是本申请实施例提供的又一种拾音系统的示意图；
图4是本申请实施例提供的第一种压电声学传感器的结构示意图；
图5是本申请实施例提供的第二种压电声学传感器的结构示意图；
图6是本申请实施例提供的第三种压电声学传感器的结构示意图；
图7是本申请实施例提供的第四种压电声学传感器的结构示意图；
图8是本申请实施例提供的第五种压电声学传感器的结构示意图；
图9是本申请实施例提供的第六种压电声学传感器的结构示意图；
图10是本申请实施例提供的一种压电单元的中性轴的示意图；
图11是本申请实施例提供的另一种压电单元的中性轴的示意图；
图12是本申请实施例提供的一种镂空结构件的结构示意图；
图13是本申请实施例提供的另一种镂空结构件的结构示意图；
图14是本申请实施例提供的又一种镂空结构件的结构示意图；
图15是本申请实施例提供的一种镂空结构件与压电单元的连接示意图；
图16是本申请实施例提供的另一种镂空结构件与压电单元的连接示意图；
图17是本申请实施例提供的又一种镂空结构件与压电单元的连接示意图；
图18是本申请实施例提供的第七种压电声学传感器的结构示意图；
图19是本申请实施例提供的第八种压电声学传感器的结构示意图；
图20是本申请实施例提供的第九种压电声学传感器的结构示意图；
图21是本申请实施例提供的第十种压电声学传感器的结构示意图；
图22是本申请实施例提供的第十一种压电声学传感器的结构示意图；
图23是本申请实施例提供的第十二种压电声学传感器的结构示意图；
图24是本申请实施例提供的一种牺牲层的去除过程示意图；
图25是本申请实施例提供的另一种牺牲层的去除过程示意图；
图26是本申请实施例提供的一种压电声学传感器的制造方法的流程图；
图27是本申请实施例提供的一种压电声学传感器的制造过程的示意图；
图28是本申请实施例提供的另一种压电声学传感器的制造过程的示意图。
附图标记：
1：锚定单元，2：压电单元，21：下电极，22：压电材料，221：第一压电材料，222：第二压电材料，23：上电极，24：中电极，3：支撑单元，4：镂空结构件，5：背腔，6：凹槽，7：牺牲层。
具体实施方式
为使本申请的目的、技术方案和优点更加清楚，下面将结合附图对本申请的实施方式作进一步地详细描述。
在对本申请实施例进行详细地解释说明之前，先对本申请实施例涉及的应用场景予以说明。
麦克风是将声信号转换为电信号的声电能量转换器件。麦克风的应用非常广泛，从手机、降噪耳麦、无线蓝牙耳机到智能音箱等，麦克风深入到人们生活的方方面面。下面以手机和智能音箱为例来对麦克风的应用进行介绍。
随着互联网技术的高速发展，手机功能越来越多，集成度越来越高。手机中一般会有两个麦克风进行拾音。其中一个麦克风是主麦克风，用于拾取通话的语音；另一个麦克风用于拾取背景音，通常安装在手机背面，且远离主麦克风。这两个麦克风在内部有主板隔离。这样的设计可以有效抵御手机周边的环境噪声干扰，大大提高通话清晰度。除了这两个麦克风之外，手机中还可以设置有其它麦克风，比如可以在后置摄像头旁边布置一个麦克风，以便在通过后置摄像头录制视频时可以更容易的接收到不同方位的声音。当然，也可以在前置摄像头旁边布置一个麦克风，以便在通过前置摄像头录制视频时可以更好的拾取不同方位的声音。
随着物联网概念的兴起，智能家居在日常生活中越来越普及。包括电视、冰箱、空调、风扇、电灯等设备都加入了智能控制的行列。如何控制这些设备，成为人们普遍关注的话题。在经历了独立遥控器、手机自带遥控、第三方遥控这些尝试以后，终于迎来了智能音箱这个 用语音来控制的方式。智能音箱中设置有由多个麦克风组成的麦克风阵列，麦克风阵列能达成语音增强、声源定位、去混响、声源信号提取(分离)等功能，这就为在复杂环境中执行语音控制提供了可能。
基于微机电系统(micro electro mechanical systems，MEMS)制造的压电式麦克风(即压电MEMS麦克风)因其小型化、可批量化生产、高性能等优点而被广泛采用。压电MEMS麦克风中可以设置压电声学传感器来采集声音，压电声学传感器具有高信噪比、低功耗、高灵敏度等诸多优点。
随着诸如手机、智能音箱等电子设备对定向拾音的需求日益增加，电子设备中需要设置越来越多的麦克风。为了保证定向拾音效果，需要保持电子设备中麦克风的性能一致性，也就是需要保持压电声学传感器的性能一致性。
然而，压电声学传感器的制造工艺存在不均匀性，因而会导致制造出的压电声学传感器的残余应力无法保持一致，从而导致压电声学传感器的谐振频率不一致，甚至灵敏度不一致的情况，进而引起压电声学传感器的输出响应性能不一致。
为此，本申请实施例提供了一种压电声学传感器，增加了镂空结构件的设计，可以改善因残余应力而导致的谐振频率漂移、灵敏度下降等问题，有助于提高压电声学传感器的性能一致性。
本申请实施例提供的压电声学传感器主要应用于手机、智能音箱、无线蓝牙耳机、降噪耳麦、笔记本、汽车等领域中，作为拾音器件来使用。压电声学传感器主要用来还原人声或者环境声音，如压电声学传感器可以完成手机通话时的人声采集，又如多个压电声学传感器形成阵列可以实现智能音箱的定向拾音。
图1是本申请实施例提供的一种拾音系统的示意图，如图1所示，该拾音系统包括压电声学传感器100和放大电路101。压电声学传感器100可以感知声音，将振动的声信号转化为原始的电信号。由于原始的电信号微弱，无法直接使用，所以一般通过放大电路101将原始的电信号进行放大处理，放大后的电信号进入音频系统102完成处理。
如图2和图3(未示出金属壳201)所示，该拾音系统可以是由金属壳201、印制电路板(printed circuit board，PCB)/陶瓷板202形成的闭合的声音腔室。在PCB/陶瓷板202上，布置有压电声学传感器100和放大电路101(包括但不限于特定应用集成电路(application-specific integrated circuit，ASIC)芯片等)。其中PCB/陶瓷板202上有进声孔2021，以便声音振动可以传递至压电声学传感器100上。压电声学传感器100与放大电路101之间通过引线进行电连接，压电声学传感器100采集的声学电信号可以通过放大电路101放大后供音频系统102进行处理。
图4、图5、图6或图7是本申请实施例提供的一种压电声学传感器的结构示意图。图5具体是图4所示的压电声学传感器的剖面图，图7具体是图6所示的压电声学传感器的剖面图。参见图4-图7，该压电声学传感器包括锚定单元1、压电单元2、支撑单元3和镂空结构件4。
锚定单元1中形成有背腔5。压电单元2用于将进入背腔5的声信号转为电信号。支撑单元3覆盖于锚定单元1和压电单元2上。镂空结构件4连接于锚定单元1与压电单元2之 间，且内嵌于支撑单元3中。
下面分别对锚定单元1、压电单元2、支撑单元3和镂空结构件4进行说明：
锚定单元1用于固定压电声学传感器中的各个组件，该压电声学传感器中的其它组件均是在锚定单元1上形成。锚定单元1具有背腔5，背腔5为进声孔，压电单元2悬浮在背腔5上方，可以将进入背腔5的声信号转为电信号。
其中，锚定单元1可以包括衬底层11和绝缘层12，绝缘层12覆盖于衬底层11上。衬底层11的材料可以是硅、石英、绝缘衬底上的硅(Silicon-On-Insulator，SOI)、碳化硅(SiC)等材料。绝缘层12的材料可以是氮化硅或其他介质材料。
压电单元2可以是压电堆叠薄膜，可以包括电极和压电材料，电极的材料可以是钼、钛、铂、铝等，压电材料可以是氮化铝、氮化钪铝、锆钛酸铅等。压电单元2可以将机械运动转化为电信号。具体地，当声信号引起压电材料振动时，压电材料中应力集中的区域会其上下电极之间产生电势差，这样就可以将声信号转化为电信号提取出来。
另外，压电单元2的形状可以根据实际需要进行设置。比如，如图4或图6所示，压电单元2可以是圆形。或者，如图8或图9所示，压电单元2可以是多边形。
一种可能的方式中，如图4、图5或图8所示，压电单元2可以是单压电晶片，压电单元2可以包括下电极21、压电材料22和上电极23。压电材料22位于下电极21与上电极23之间。
另一种可能的方式中，如图6、图7或图9所示，压电单元2可以是双压电晶片，压电单元2可以包括下电极21、第一压电材料221、中电极24、第二压电材料222和上电极23。第一压电材料221位于下电极21与中电极24之间，第二压电材料222位于中电极24与上电极23之间。
支撑单元3用于固定锚定单元1、镂空结构件4和压电单元2的位置，以增强压电声学传感器的机械强度。支撑单元3的材料可以为多晶硅、氮化硅或二氧化硅等。
另外，由于镂空结构件4连接在锚定单元1与压电单元2之间，所以支撑单元3覆盖于锚定单元1和压电单元2上后，支撑单元3会包裹镂空结构件4，即镂空结构件4会内嵌于支撑单元3中。如此，支撑单元3就实现了对锚定单元1、镂空结构件4和压电单元2这三者位置的固定。
再者，镂空结构件4内嵌于支撑单元3中，即是支撑单元3会填充镂空结构件4中的镂空间隙，如此可以调整压电声学传感器的本征谐振频率，减小镂空间隙造成的声漏，提升压电声学传感器的低频响应性能。
一种可能的情况下，如图4、图5或图8所示，压电单元2是单压电晶片时，压电单元2的上表面全部覆盖有支撑单元3。
这种情况下，如图10所示，支撑单元3的存在可以使得压电单元2的中性轴m远离压电单元2的中心(即远离压电材料22)，从而可以有效提升压电声学传感器的电荷输出和灵敏度。
另一种可能的情况下，如图6、图7或图9所示，压电单元2是双压电晶片，压电单元2的上表面部分覆盖有支撑单元3。例如，压电单元2的上表面的边缘部位覆盖有支撑单元3，压电单元2的上表面的中心部位未覆盖有支撑单元3，即支撑单元3中位于压电单元2的上方的部分的中心区域被掏空。
这种情况下，如图11所示，可以保证压电单元2的中性轴m位于压电单元2的中电极24中，从而不会影响压电声学传感器的电荷输出和灵敏度。
镂空结构件4为去除部分材料的机械结构，具有低刚度、易形变的特性。例如，如图12所示，镂空结构件4的形状可以是弯折状，弯折状的镂空结构件4的弯折部的宽度w1可以为1至10微米，弯折部之间的间隙宽度w2可以大于0.5微米。或者，如图13所示，镂空结构件4的形状可以是回形状，回形状的镂空结构件4的回形部的宽度w3可以为1至10微米，镂空区域的宽度w4可以大于2微米。或者，如图14所示，镂空结构件4的形状可以是网格状，网格状的镂空结构件4的镂空区域的宽度w5可以大于1微米。
需要说明的是，镂空结构件4连接在锚定单元1与压电单元2之间。也即是，镂空结构件4的第一端可以固定在锚定单元1的上表面(即绝缘层12的上表面)，镂空结构件4的第二端可以与压电单元2连接。
另外，镂空结构件4可以起到应力释放作用。镂空结构件4的数量可以根据使用需求进行设置。为了提升应力释放效果，镂空结构件4的数量可以大于或等于2。进一步地，至少两个镂空结构件4还可以均匀分布在压电单元2周围。例如，如图15所示，镂空结构件4的数量可以是2，且这两个镂空结构件4可以均匀分布在压电单元2周围。或者，如图16所示，镂空结构件4的数量可以是3，且这3个镂空结构件4可以均匀分布在压电单元2周围。或者，如图17所示，镂空结构件4的数量可以是8，且这8个镂空结构件4可以均匀分布在压电单元2周围。
其中，镂空结构件4可以与压电单元2中的电极和压电材料中的至少一个连接。并且，当镂空结构件4与压电单元2中的电极连接时，镂空结构件4可以与其所连接的电极采用同一种材料。当镂空结构件4与压电单元2中的压电材料连接时，镂空结构件4可以与其所连接的压电材料采用同一种材料。当镂空结构件4分别与压电单元2中的电极和压电材料连接时，也即是当镂空结构件4中的一部分与压电单元2中的电极连接且另一部分与压电单元2中的压电材料连接时，镂空结构件4中的一部分可以与所连接的电极采用同一种材料，镂空结构件4中的另一部分可以与所连接的压电材料采用同一种材料。这种情况下，镂空结构件4可以是多层结构，镂空结构件4中的每一层可以与电极或压电材料连接，且每一层与其所连接的电极或压电材料采用同一种材料。
如此，在制造压电单元2中的电极或压电材料的同时可以制造与其所连接的镂空结构件4，从而简化了制造工艺，节省了制造成本和制造时间。
一种可能的方式中，在图4、图5或图8所示的压电单元2中，即在压电单元2包括下电极21、压电材料22和上电极23这三部分时，镂空结构件4可以与这三部分中的任意一部分连接。并且，当镂空结构件4的数量大于或等于2时，至少两个镂空结构件4均可以连接压电单元2中的一个部分，或各个镂空结构件4可以分别连接压电单元2中不同的部分。
例如，如图5所示，至少两个镂空结构件4均连接压电单元2中的下电极21。或者，如图18所示，至少两个镂空结构件4中的至少一个镂空结构件4连接压电单元2中的上电极23，其它镂空结构件4连接压电单元2中的下电极21。
另一种可能的方式中，在图6、图7或图9所示的压电单元2中，即在压电单元2包括下电极21、第一压电材料221、中电极24、第二压电材料222和上电极23这五部分时，镂空结构件4可以与这五部分中的任意一部分连接。并且，当镂空结构件4的数量大于或等于 2时，至少两个镂空结构件4均可以连接压电单元2中的一个部分，或各个镂空结构件4可以分别连接压电单元2中不同的部分。
例如，如图7所示，至少两个镂空结构件4均连接压电单元2中的下电极21。或者，如图19所示，至少两个镂空结构件4中的至少一个镂空结构件4连接压电单元2中的中电极24，其它镂空结构件4连接压电单元2中的下电极21。或者，如图20所示，至少两个镂空结构件4中的至少一个镂空结构件4连接压电单元2中的上电极23，其它镂空结构件4连接压电单元2中的下电极21。或者，如图21所示，至少两个镂空结构件4均连接压电单元2中的中电极24。或者，如图22所示，至少两个镂空结构件4均连接压电单元2中的上电极23。或者，如图23所示，至少两个镂空结构件4中的至少一个镂空结构件4连接压电单元2中的上电极23，其它镂空结构件4连接压电单元2中的中电极24。
下面对在压电声学传感器中增加镂空结构件4后能够取得的有益效果进行说明：
如图24或图25所示，在压电声学传感器的制造过程中，往往是先形成牺牲层7，再在牺牲层7之上形成压电单元2，然后再去除牺牲层7。这种情况下，一方面，镂空结构件4可以起到机械连接作用，在去除压电单元2下方的牺牲层7的过程中，压电单元2可以通过镂空结构件4与锚定单元1连接，从而可以避免压电单元2在牺牲层7的去除过程中脱落。另一方面，镂空结构件4可以起到应力释放作用，在去除压电单元2下方的牺牲层7的过程中，低刚度、易形变的镂空结构件4通过镂空间隙的变化允许压电单元2进行活动(如上下弯曲或水平伸缩)，压电单元2的残余应力通过可形变的镂空结构件4释放，实现零残余应力。由于压电单元2的残余应力已经释放，因此相同几何尺寸的压电声学传感器具有一致的谐振频率和灵敏度。
在本申请实施例中，压电声学传感器包括锚定单元1、压电单元2、支撑单元3和镂空结构件4。锚定单元1中形成有背腔5。压电单元2用于将进入背腔5的声信号转为电信号。支撑单元3覆盖于锚定单元1和压电单元2上。镂空结构件4连接于锚定单元1与压电单元2之间，且内嵌于支撑单元3中。压电单元2的残余应力在制造过程中可以通过可形变的镂空结构件4释放，实现零残余应力，因而可以避免压电声学传感器的谐振频率漂移，以及避免压电声学传感器的灵敏度下降，进而有助于提高压电声学传感器的性能一致性。
图26是本申请实施例提供的一种图4-图25中所示的压电声学传感器的制造方法的流程图。参见图26，该方法包括：
步骤2601：提供一锚定单元，在锚定单元的上表面刻蚀凹槽。
如图27或图28中的a所示，提供一锚定单元1，然后在锚定单元1的上表面刻蚀凹槽6。
锚定单元1用于固定压电声学传感器中的各个组件，该压电声学传感器中的其它组件可以在锚定单元1上形成。
其中，锚定单元1可以包括衬底层11和绝缘层12。这种情况下，提供一锚定单元1时，可以先提供一衬底层11，再在衬底层11之上形成绝缘层12。
需要说明的是，衬底层11的材料可以是硅、石英、SOI、SiC等材料。绝缘层12的材料可以是氮化硅或其他介质材料。
另外，在衬底层11之上形成绝缘层12可以是在衬底层11的上表面沉积用于形成绝缘层12的材料得到绝缘层12。
其中，在锚定单元1的上表面刻蚀凹槽6时，可以先在绝缘层12的上表面定义凹槽6的形状和位置，以确定绝缘层12的上表面中凹槽6所在区域。之后，先将绝缘层12的上表面中除凹槽6所在区域之外的其它区域通过保护胶进行保护，再对绝缘层12的上表面进行刻蚀，得到绝缘层12的上表面中的凹槽6。
需要说明的是，定义凹槽6的形状和位置时，可以通过光刻工艺来定义，如可以通过电子束曝光、光学曝光等光刻工艺来定义。
另外，保护胶可以为抗刻蚀的胶、聚甲基丙烯酸甲酯(Poly(methyl methacrylate)，PMMA)等。
再者，对绝缘层12的上表面进行刻蚀时，可以通过反应离子刻蚀(Reactive-Ion Etching，RIE)、氧等离子刻蚀等工艺进行刻蚀。
步骤2602：在该凹槽内填充牺牲层。
如图27或图28中的b所示，在锚定单元1的上表面中的凹槽6内填充牺牲层7，具体可以在锚定单元1的上表面中的凹槽6内沉积用于形成牺牲层7的材料得到牺牲层7。牺牲层7的材料可以是二氧化硅、掺磷氧化硅等容易被化学刻蚀剂腐蚀掉的材料。
步骤2603：在牺牲层之上形成压电单元，以及在锚定单元和牺牲层之上形成镂空结构件。
如图27或图28中的c所示，在牺牲层7之上形成压电单元2，以及在锚定单元1和牺牲层7之上形成镂空结构件4。
需要说明的是，压电单元2可以是压电堆叠薄膜，可以包括电极和压电材料，电极的材料可以是钼、钛、铂、铝等，压电材料可以是氮化铝、氮化钪铝、锆钛酸铅等。压电单元2可以将机械运动转化为电信号。具体地，当声信号引起压电材料振动时，压电材料中应力集中的区域会其上下电极之间产生电势差，这样就可以将声信号转化为电信号提取出来。
另外，压电单元2的下表面的面积小于牺牲层7的上表面的面积，也即是，压电单元2完全位于牺牲层7的上表面上。
其中，在牺牲层7之上形成压电单元2时，可以在牺牲层7的上表面定义压电单元2的形状和位置，以确定牺牲层7的上表面中压电单元2所在区域。之后，在牺牲层7的上表面中压电单元2所在区域上沉积用于形成压电单元2的材料得到压电单元2。
需要说明的是，定义压电单元2的形状和位置时，可以通过光刻工艺来定义，如可以通过电子束曝光、光学曝光等光刻工艺来定义。
一种可能的方式中，如图27所示，压电单元2可以是单压电晶片，压电单元2可以包括下电极21、压电材料22和上电极23。这种情况下，在牺牲层7之上形成压电单元2时，可以在牺牲层7之上形成下电极21，在下电极21之上形成压电材料22，在压电材料22之上形成上电极23。
也就是说，可以在牺牲层7的上表面上沉积用于形成下电极21的材料得到下电极21，再在下电极21的上表面上沉积压电材料22，最后在压电材料22的上表面上沉积用于形成上电极23的材料得到上电极23。
另一种可能的方式中，如图28所示，压电单元2可以是双压电晶片，压电单元2可以包括下电极21、第一压电材料221、中电极24、第二压电材料222和上电极23。这种情况下，在牺牲层7之上形成压电单元2时，可以在牺牲层7之上形成下电极21，在下电极21之上形成第一压电材料221，在第一压电材料221之上形成中电极24，在中电极24之上形成第二 压电材料222，在第二压电材料222之上形成上电极23。
也就是说，可以在牺牲层7的上表面上沉积用于形成下电极21的材料得到下电极21，再在下电极21的上表面上沉积第一压电材料221，在第一压电材料221的上表面上沉积用于形成中电极24的材料得到中电极24，接着在中电极24的上表面上沉积第二压电材料222，在第二压电材料222的上表面上沉积用于形成上电极23的材料得到上电极23。
需要说明的是，镂空结构件4为去除部分材料的机械结构，具有低刚度、易形变的特性。镂空结构件4的形状可以根据使用需求进行设置，例如，镂空结构件4的形状可以是弯折状、回形状、网格状等。
另外，镂空结构件4连接在锚定单元1与压电单元2之间。也即是，镂空结构件4的第一端可以固定在锚定单元1的上表面(即绝缘层12的上表面)，镂空结构件4的第二端可以与压电单元2连接。
再者，镂空结构件4可以起到应力释放作用。镂空结构件4的数量可以根据使用需求进行设置。为了提升应力释放效果，镂空结构件4的数量可以大于或等于2。进一步地，至少两个镂空结构件4还可以均匀分布在压电单元2周围。
其中，镂空结构件4可以与压电单元2中的电极和压电材料中的至少一个连接。并且，当镂空结构件4与压电单元2中的电极连接时，镂空结构件4可以与其所连接的电极采用同一种材料。当镂空结构件4与压电单元2中的压电材料连接时，镂空结构件4可以与其所连接的压电材料采用同一种材料。当镂空结构件4分别与压电单元2中的电极和压电材料连接时，也即是当镂空结构件4中的一部分与压电单元2中的电极连接且另一部分与压电单元2中的压电材料连接时，镂空结构件4中的一部分可以与所连接的电极采用同一种材料，镂空结构件4中的另一部分可以与所连接的压电材料采用同一种材料。这种情况下，镂空结构件4可以是多层结构，镂空结构件4中的每一层可以与电极或压电材料连接，且每一层与其所连接的电极或压电材料采用同一种材料。
如此，在制造压电单元2中的电极或压电材料的同时可以制造与其所连接的镂空结构件4，从而简化了制造工艺，节省了制造成本和制造时间。
一种可能的方式中，在图27所示的压电单元2中，即在压电单元2包括下电极21、压电材料22和上电极23这三部分时，镂空结构件4可以与这三部分中的任意一部分连接。并且，当镂空结构件4的数量大于或等于2时，至少两个镂空结构件4均可以连接压电单元2中的一个部分，或各个镂空结构件4可以分别连接压电单元2中不同的部分。
例如，至少两个镂空结构件4均连接压电单元2中的下电极21。或者，至少两个镂空结构件4中的至少一个镂空结构件4连接压电单元2中的上电极23，其它镂空结构件4连接压电单元2中的下电极21。
另一种可能的方式中，在图28所示的压电单元2中，即在压电单元2包括下电极21、第一压电材料221、中电极24、第二压电材料222和上电极23这五部分时，镂空结构件4可以与这五部分中的任意一部分连接。并且，当镂空结构件4的数量大于或等于2时，至少两个镂空结构件4均可以连接压电单元2中的一个部分，或各个镂空结构件4可以分别连接压电单元2中不同的部分。
例如，至少两个镂空结构件4均连接压电单元2中的下电极21。或者，至少两个镂空结构件4中的至少一个镂空结构件4连接压电单元2中的中电极24，其它镂空结构件4连接压 电单元2中的下电极21。或者，至少两个镂空结构件4中的至少一个镂空结构件4连接压电单元2中的上电极23，其它镂空结构件4连接压电单元2中的下电极21。或者，至少两个镂空结构件4均连接压电单元2中的中电极24。或者，至少两个镂空结构件4均连接压电单元2中的上电极23。或者，至少两个镂空结构件4中的至少一个镂空结构件4连接压电单元2中的上电极23，其它镂空结构件4连接压电单元2中的中电极24。
其中，在锚定单元1和牺牲层7之上形成镂空结构件4时，可以在锚定单元1的上表面和牺牲层7的上表面定义镂空结构件4的形状和位置，以确定锚定单元1的上表面和牺牲层7的上表面中镂空结构件4所在区域。之后，在镂空结构件4所在区域上沉积用于形成镂空结构件4的材料得到镂空结构件4。
需要说明的是，定义镂空结构件4的形状和位置时，可以通过光刻工艺来定义，如可以通过电子束曝光、光学曝光等光刻工艺来定义。
步骤2604：去除牺牲层。
如图27或图28中的d所示，可以去除牺牲层7。去除牺牲层7时一般可以使用化学刻蚀剂将牺牲层7腐蚀掉。例如，当牺牲层7的材料为二氧化硅时，可以使用液态氢氟酸刻蚀二氧化硅，以去除二氧化硅。
这种情况下，一方面，镂空结构件4可以起到机械连接作用，在去除压电单元2下方的牺牲层7的过程中，压电单元2可以通过镂空结构件4与锚定单元1连接，从而可以避免压电单元2在牺牲层7的去除过程中脱落，此时压电单元2可以通过镂空结构件4悬浮在凹槽6的上方。另一方面，镂空结构件4可以起到应力释放作用，在去除压电单元2下方的牺牲层7的过程中，低刚度、易形变的镂空结构件4通过镂空间隙的变化允许压电单元2进行活动(如上下弯曲或水平伸缩)，压电单元2的残余应力通过可形变的镂空结构件4释放，实现零残余应力。由于压电单元2的残余应力已经释放，因此最终制造出的相同几何尺寸的压电声学传感器具有一致的谐振频率和灵敏度。
由于压电单元2之前是完全位于牺牲层7上，所以在去除牺牲层7后，当压电单元2的残余应力释放完毕且各个器件(包括锚定单元1、压电单元2和镂空结构件4)干燥后，压电单元2会在重力作用下下降至原先牺牲层7所在的凹槽6内并与凹槽6的槽底接触。也即是，当压电单元2的残余应力释放完毕且各个器件干燥后，压电单元2会贴附在锚定单元1的表面。
步骤2605：当压电单元与该凹槽的槽底接触时，在锚定单元和压电单元之上形成支撑单元，支撑单元包裹在镂空结构件外。
如图27或图28中的e所示，在压电单元2与凹槽6的槽底接触时，可以在锚定单元1和压电单元2之上形成支撑单元3，此时支撑单元3会包裹在镂空结构件4外。
需要说明的是，支撑单元3用于固定锚定单元1、镂空结构件4和压电单元2的位置，以增强最终制造出的压电声学传感器的机械强度。支撑单元3的材料可以为多晶硅、氮化硅或二氧化硅等。
另外，由于镂空结构件4连接在锚定单元1与压电单元2之间，所以在锚定单元1和压电单元2之上形成支撑单元3之后，支撑单元3会包裹镂空结构件4外。也就是说，支撑单元3覆盖于锚定单元1和压电单元2上，而镂空结构件4内嵌于支撑单元3中，如此，支撑单元3就实现了对锚定单元1、镂空结构件4和压电单元2这三者位置的固定。
再者，支撑单元3会包裹在镂空结构件4外，即是支撑单元3会填充镂空结构件4中的镂空间隙，如此可以调整最终制造出的压电声学传感器的本征谐振频率，减小镂空间隙造成的声漏，提升压电声学传感器的低频响应性能。
一种可能的方式中，在图27所示的压电单元2中，即在压电单元2包括下电极21、压电材料22和上电极23时，可以直接在锚定单元1的上表面和压电单元2的上表面沉积支撑单元3，所沉积的支撑单元3将会包裹镂空结构件4。
这种情况下，压电单元2的上表面上全部覆盖有支撑单元3。如此，支撑单元3的存在可以使得压电单元2的中性轴远离压电单元2的中心(即远离压电材料22)，从而可以有效提升最终制造出的压电声学传感器的电荷输出和灵敏度。
其中，在锚定单元1的上表面和压电单元2的上表面沉积支撑单元3时，可以先在锚定单元1的上表面和压电单元2的上表面定义支撑单元3的形状和位置，以确定锚定单元1的上表面和压电单元2的上表面中支撑单元3所在区域。之后，在支撑单元3所在区域上沉积用于形成支撑单元3的材料得到支撑单元3。
需要说明的是，定义支撑单元3的形状和位置时，可以通过光刻工艺来定义，如可以通过电子束曝光、光学曝光等光刻工艺来定义。
另一种可能的方式中，在图28所示的压电单元2中，即在压电单元2包括下电极21、第一压电材料221、中电极24、第二压电材料222和上电极23时，可以先在锚定单元1的上表面和压电单元2的上表面沉积支撑单元3，所沉积的支撑单元3将会包裹镂空结构件4，然后再去除支撑单元3中沉积在压电单元2的上表面上的至少一部分。
这种情况下，压电单元2的上表面部分覆盖有支撑单元3。例如，可以去除支撑单元3中沉积在压电单元2的上表面的中心部位上的一部分，此时压电单元2的上表面的边缘部位覆盖有支撑单元3，压电单元2的上表面的中心部位未覆盖有支撑单元3，即支撑单元3中位于压电单元2的上方的部分的中心区域被掏空。如此可以保证压电单元2的中性轴位于压电单元2的中电极24中，从而不会影响最终制造出的压电声学传感器的电荷输出和灵敏度。
其中，去除支撑单元3中沉积在压电单元2的上表面上的至少一部分时，可以先在支撑单元3的上表面定义目标部分的形状和位置，以确定支撑单元3的上表面中目标部分所在区域，目标部分为沉积在压电单元2的上表面上的至少一部分。之后，先将支撑单元3的上表面中除目标部分所在区域之外的其它区域通过保护胶进行保护，再对支撑单元3的上表面进行刻蚀，以去除支撑单元3中的目标部分。
要说明的是，定义目标部分的形状和位置时，可以通过光刻工艺来定义，如可以通过电子束曝光、光学曝光等光刻工艺来定义。
另外，对支撑单元3的上表面进行刻蚀时，可以通过反应离子刻蚀、氧等离子刻蚀等工艺进行刻蚀。
步骤2606：在该凹槽的槽底与锚定单元的下表面之间的部位刻蚀背腔。
如图27或图28中的f所示，在凹槽6的槽底与锚定单元1的下表面之间的部位刻蚀背腔5。背腔5为进声孔，此时压电单元2悬浮在进声孔上方，可以感知声音。
在本申请实施例中，提供一锚定单元，在锚定单元的上表面刻蚀凹槽，然后在该凹槽内填充牺牲层。在牺牲层之上形成压电单元，以及在锚定单元和牺牲层之上形成镂空结构件，镂空结构件连接在锚定单元与压电单元之间。之后，去除牺牲层。当压电单元与凹槽的槽底 接触时，在锚定单元和压电单元之上形成支撑单元，支撑单元包裹在镂空结构件外。最后，在该凹槽的槽底与锚定单元的下表面之间的部位刻蚀背腔，得到压电声学传感器。在此制造过程中，压电单元的残余应力可以通过可形变的镂空结构件释放，实现零残余应力，因而可以避免压电声学传感器的谐振频率漂移，以及避免压电声学传感器的灵敏度下降，进而有助于提高压电声学传感器的性能一致性。
以上所述为本申请提供的实施例，并不用以限制本申请，凡在本申请的精神和原则之内，所作的任何修改、等同替换、改进等，均应包含在本申请的保护范围之内。

Claims (16)

  1. 一种压电声学传感器，其特征在于，所述压电声学传感器包括：锚定单元、压电单元、支撑单元和镂空结构件；
    所述锚定单元中形成有背腔；
    所述压电单元用于将进入所述背腔的声信号转为电信号；
    所述支撑单元覆盖于所述锚定单元和所述压电单元上；
    所述镂空结构件连接于所述锚定单元与所述压电单元之间，且内嵌于所述支撑单元中。
  2. 如权利要求1所述的压电声学传感器，其特征在于，所述压电单元包括电极和压电材料；所述镂空结构件与所述电极和所述压电材料中的至少一个连接。
  3. 如权利要求2所述的压电声学传感器，其特征在于，所述镂空结构件与所述电极连接，所述镂空结构件与所述电极采用同一种材料；或者
    所述镂空结构件与所述压电材料连接，所述镂空结构件与所述压电材料采用同一种材料；或者
    所述镂空结构件分别与所述电极和所述压电材料连接，所述镂空结构件中的一部分与所述电极采用同一种材料，所述镂空结构件中的另一部分与所述压电材料采用同一种材料。
  4. 如权利要求2或3所述的压电声学传感器，其特征在于，所述压电单元包括下电极、压电材料和上电极，所述压电材料位于所述下电极与所述上电极之间；所述压电单元的上表面全部覆盖有所述支撑单元。
  5. 如权利要求2或3所述的压电声学传感器，其特征在于，所述压电单元包括下电极、第一压电材料、中电极、第二压电材料和上电极，所述第一压电材料位于所述下电极与所述中电极之间，所述第二压电材料位于所述中电极与所述上电极之间；所述压电单元的上表面部分覆盖有所述支撑单元。
  6. 如权利要求1-5任一所述的压电声学传感器，其特征在于，所述镂空结构件的数量大于或等于2。
  7. 如权利要求1-6任一所述的压电声学传感器，其特征在于，所述镂空结构件的形状为弯折状、回形状、或网格状。
  8. 如权利要求1-7任一所述的压电声学传感器，其特征在于，所述锚定单元包括衬底层和绝缘层，所述绝缘层覆盖于所述衬底层上。
  9. 一种压电声学传感器的制造方法，其特征在于，所述方法包括：
    提供一锚定单元；
    在所述锚定单元的上表面刻蚀凹槽；
    在所述凹槽内填充牺牲层；
    在所述牺牲层之上形成压电单元，以及在所述锚定单元和所述牺牲层之上形成镂空结构件，所述压电单元的下表面的面积小于所述牺牲层的上表面的面积，所述镂空结构件连接在所述锚定单元与所述压电单元之间；
    去除所述牺牲层；
    当所述压电单元与所述凹槽的槽底接触时，在所述锚定单元和所述压电单元之上形成支撑单元，所述支撑单元包裹在所述镂空结构件外；
    在所述凹槽的槽底与所述锚定单元的下表面之间的部位刻蚀背腔。
  10. 如权利要求9所述的方法，其特征在于，所述压电单元包括电极和压电材料；所述镂空结构件与所述电极和所述压电材料中的至少一个连接。
  11. 如权利要求10所述的方法，其特征在于，所述镂空结构件与所述电极连接，所述镂空结构件与所述电极采用同一种材料；或者
    所述镂空结构件与所述压电材料连接，所述镂空结构件与所述压电材料采用同一种材料；或者
    所述镂空结构件分别与所述电极和所述压电材料连接，所述镂空结构件中的一部分与所述电极采用同一种材料，所述镂空结构件中的另一部分与所述压电材料采用同一种材料。
  12. 如权利要求10或11所述的方法，其特征在于，所述在所述牺牲层之上形成压电单元，包括：
    在所述牺牲层之上形成下电极；
    在所述下电极之上形成压电材料；
    在所述压电材料之上形成上电极；
    所述在所述锚定单元和所述压电单元之上形成支撑单元，包括：
    在所述锚定单元的上表面和所述压电单元的上表面沉积支撑单元。
  13. 如权利要求10或11所述的方法，其特征在于，所述在所述牺牲层之上形成压电单元，包括：
    在所述牺牲层之上形成下电极；
    在所述下电极之上形成第一压电材料；
    在所述第一压电材料之上形成中电极；
    在所述中电极之上形成第二压电材料；
    在所述第二压电材料之上形成上电极；
    所述在所述锚定单元和所述压电单元之上形成支撑单元，包括：
    在所述锚定单元的上表面和所述压电单元的上表面沉积支撑单元；
    去除所述支撑单元中沉积在所述压电单元的上表面上的至少一部分。
  14. 如权利要求9-13任一所述的方法，其特征在于，所述镂空结构件的数量大于或等于2。
  15. 如权利要求9-14任一所述的方法，其特征在于，所述镂空结构件的形状为弯折状、回形状、或网格状。
  16. 如权利要求9-15任一所述的方法，其特征在于，所述提供一锚定单元，包括：
    提供一衬底层；
    在所述衬底层之上形成绝缘层。
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