WO2024051509A1 - 具有可拉伸膜的mems扬声器、其制造方法以及包括其的电子设备 - Google Patents

具有可拉伸膜的mems扬声器、其制造方法以及包括其的电子设备 Download PDF

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Publication number
WO2024051509A1
WO2024051509A1 PCT/CN2023/115188 CN2023115188W WO2024051509A1 WO 2024051509 A1 WO2024051509 A1 WO 2024051509A1 CN 2023115188 W CN2023115188 W CN 2023115188W WO 2024051509 A1 WO2024051509 A1 WO 2024051509A1
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Prior art keywords
diaphragm
stretchable film
stretchable
speaker
mems
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PCT/CN2023/115188
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English (en)
French (fr)
Inventor
张孟伦
徐林炳
孙铭超
庞慰
Original Assignee
广州乐仪投资有限公司
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Publication of WO2024051509A1 publication Critical patent/WO2024051509A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H04R19/02—Loudspeakers
    • 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

Definitions

  • Embodiments of the present invention relate to the field of semiconductors, and in particular, to a MEMS speaker with a stretchable film, a manufacturing method thereof, and an electronic device including the same.
  • MEMS Micro-electro Mechanical Systems, Micro-Electro-Mechanical Systems
  • speaker is a miniature transducer that converts electrical signals into acoustic signals. Its core components (such as actuators/drivers, diaphragms, thermoacoustic membranes, etc.) use MEMS technology Manufactured on semiconductor materials. MEMS speakers can be divided into piezoelectric, electric, electrostatic and thermoacoustic types according to their working principles.
  • piezoelectric MEMS speakers The working principle of piezoelectric MEMS speakers is to use piezoelectric films as transducer elements, which deform when voltage is applied. This mechanical deflection displaces the surrounding air and creates sound waves.
  • a major advantage of the piezoelectric MEMS speaker is its compatibility with semiconductor processes, which means it can be produced at low cost in large volumes and in extremely small sizes. In addition to their size, piezoelectric MEMS speakers offer extremely low power and excellent audio quality. Piezoelectric MEMS speakers can also be built on the same PCB substrate as the amplifier, saving board space.
  • the cantilever beam diaphragm is a commonly used diaphragm structure in piezoelectric MEMS speakers.
  • the cantilever beam diaphragm structure with slits is shown in Figure 1A, Figure 1B and Figure 1C.
  • Figure 1A is a top view of multiple known cantilever beam diaphragms.
  • Figure 1B is the AA cross-section of the structure in Figure 1A. Cutaway view.
  • the MEMS speaker includes four diaphragms, namely diaphragm 60 , diaphragm 61 , diaphragm 62 and diaphragm 63 .
  • Each diaphragm is triangular, with one end fixed, for example, one end of the diaphragm 60 is fixed on the support 51 , and the remaining two ends are free ends.
  • a slit is provided between the opposite free ends of two adjacent diaphragms.
  • a slit 64 is provided between the opposite free ends of the diaphragm 60 and the diaphragm 61 . The slits reduce the constraints on the diaphragm when it vibrates.
  • the cantilever beam diaphragm shown in Figure 1C is a schematic diagram of an eight-petal structure, in which 60 is one of the eight diaphragms, 64 is the slit between the diaphragms, and 51 is the support layer of the diaphragm (for Mechanically supported or fixed diaphragm edge).
  • the sound waves on one side (for example, the upper side) of the diaphragm 61 or the diaphragm 63 will be diffracted to the other side (for example, the lower side) through the slit, causing an acoustic short circuit phenomenon, resulting in the low frequency band of the speaker.
  • the response decreases and the flatness of the frequency response curve becomes worse.
  • the present invention is proposed to alleviate or solve at least one aspect of the above-mentioned problems in the prior art.
  • a MEMS speaker including: a diaphragm, one end of the diaphragm is fixed and a space for vibration is provided between the other end and another component; a stretchable film, respectively connected with the vibrator The membrane is connected to another component and fills or covers at least part of the vibration space.
  • a method for manufacturing a MEMS speaker including the steps of: forming a MEMS speaker wafer, the speaker wafer being provided with a plurality of MEMS speakers; and providing the plurality of MEMS speakers on the speaker wafer.
  • the speaker is simultaneously provided with a stretchable membrane; cutting is performed to form multiple MEMS speakers with stretchable membranes.
  • Embodiments of the present invention also relate to an electronic device, including the above-mentioned MEMS speaker.
  • Figure 1A is a schematic top view of multiple known cantilever beam diaphragms
  • Figure 1B is a schematic cross-sectional view of the structure in Figure 1A taken along A-A;
  • Figure 1C is a schematic top view of multiple other known cantilever beam diaphragms
  • Figure 2 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention
  • Figure 3 is a simulation rendering, illustrating the sound pressure level frequency response curves of a MEMS speaker without a stretchable film and a MEMS speaker provided with stretchable films with different Young's modulus, where the stretchable film Thickness is 50 microns;
  • Figure 4A is a simulation rendering, illustrating the sound pressure level frequency response curves of a MEMS speaker without a stretchable film and a MEMS speaker provided with stretchable films of different thicknesses, in which the Young's mode of the stretchable film The amount is 0.75 MPa;
  • Figure 4B is a simulation rendering, illustrating the matching curve of the corresponding stretchable film thickness and Young's modulus when the sound pressure level drops by different decibels.
  • the dotted line represents the matching curve when the sound pressure level drops by 10 decibels.
  • the solid line represents the matching curve when the sound pressure level drops by 5 dB;
  • Figure 5 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which a stretchable membrane is disposed below the diaphragm;
  • Figure 6 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which the end of the stretchable membrane is disposed between two ends of the diaphragm and is arranged asymmetrically with respect to the vibration space;
  • FIG. 7 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which the end of the stretchable membrane is disposed between two ends of the diaphragm and is arranged symmetrically with respect to the vibration space;
  • Figure 8 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which a stretchable membrane is filled in a space for vibration;
  • Figure 9 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which a part of the stretchable membrane is provided on the surface of the diaphragm, and the other part is filled in the vibration space;
  • FIGS. 10-12 are cross-sectional schematic diagrams of MEMS speakers according to different exemplary embodiments of the present invention, in which the diaphragm and the stretchable membrane have curvature;
  • FIG. 13-15 are schematic cross-sectional views of MEMS speakers according to different exemplary embodiments of the present invention, in which there is a gap between the diaphragm and the stretchable membrane;
  • Figure 16 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which a portion of the stretchable membrane opposite to the space for vibration has a bend;
  • 17-20 are schematic top views of MEMS speakers according to different exemplary embodiments of the present invention, in which the stretchable film does not completely cover the diaphragm;
  • Figure 21 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which the diaphragm is a double piezoelectric layer structure;
  • 22 and 23 are schematic cross-sectional views of MEMS speakers according to different exemplary embodiments of the present invention, where the MEMS speaker only includes a single cantilever beam diaphragm;
  • Figures 24A and 25A are top schematic views of MEMS speakers according to different exemplary embodiments of the present invention, and Figures 24B and 25B are corresponding cross-sectional schematic views respectively, in which different diaphragms are coupled to each other in a partially connected manner;
  • Figure 26 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which an intermediate medium is provided in the gap between the stretchable film and the diaphragm;
  • Figure 27 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which the space for vibration is a groove;
  • 28A-28K are a series of cross-sectional schematic diagrams illustrating a process flow for preparing a MEMS speaker according to an exemplary embodiment of the present invention
  • 29G-29I are a series of cross-sectional schematic diagrams illustrating a process flow for preparing a MEMS speaker according to another exemplary embodiment of the present invention.
  • Figure 30 is a simulation rendering, illustrating the sound pressure level frequency response curves of a MEMS speaker with a non-stretchable film and a MEMS speaker with a stretchable film in the structure of Figure 1C;
  • Figures 31 and 32 are respectively the main strain distribution diagrams of a MEMS speaker with a non-stretchable film and a MEMS speaker with a stretchable film in the structure of Figure 1C;
  • Figure 33 is a measured sound pressure chart, illustrating the sound pressure level frequency response of a MEMS speaker without 15 ⁇ m PDMS (stretchable film) and a MEMS speaker with 15 ⁇ m PDMS (stretchable film) in the structure of Figure 1C curve.
  • Structural layer see Figure 2 for example. Its material is, for example, silicon, silicon dioxide, etc. It can also be made of piezoelectric layer or electrode material. In optional embodiments, this layer may not be used;
  • Piezoelectric layer for example, see Figure 2. Its materials are, for example, aluminum nitride (AlN), scandium-doped aluminum nitride (AlScN), lead zirconate titanate (chemical formula: Pb(Tix, Zr1-x)O3, abbreviation (PZT), zinc oxide (chemical formula: ZnO), lithium niobate (LiNbO3), etc.;
  • Electrode for example, see Figure 2. Its material is, for example, molybdenum, platinum, gold and other metals;
  • Stretchable film for example, see Figure 2, which is a film whose Young's modulus and thickness meet specific conditions,
  • polymer materials such as rubber can be used, such as silicone rubber or RTV (room-temperature-vulcanizing silicone) rubber, or PDMS (Polydimethylsiloxane, polydimethylsiloxane), etc.
  • the stretchable membrane is separated from the diaphragm (see One end of the membrane (described below) is connected to another component (such as another diaphragm or a support described below), and the above connection causes the stretchable membrane to be stretched when the diaphragm vibrates;
  • Support member see Figure 2 for example, used to support the diaphragm, made of material such as silicon;
  • Diaphragm for example, see Figure 2, which is suitable for driving air vibration through its own vibration to emit sound, including structural layer 1 (if any), piezoelectric layer 2 and electrode 3 and other components;
  • Coupling structure for example, see Figure 24A, Figure 24B, Figure 25A and Figure 25B;
  • Space for vibration see Figure 2 for example, a space that provides conditions for the diaphragm to vibrate, or a space set up to reduce or eliminate the constraints on the end of the diaphragm when vibrating, in the form of slits, holes or grooves, for example. wait;
  • SOI Silicon-On-Insulator, silicon on insulating substrate
  • Piezoelectric layer the same as the description of the piezoelectric layer above, for example, see Figure 28B;
  • First electrode layer the same as the description of the electrode above, see Figure 28A for example;
  • Second electrode layer the same as the description of the electrode above, for example, see Figure 28C;
  • part of the sound waves on one side of the diaphragm (especially the low-frequency part) will be diffracted to the other side of the diaphragm through the slits.
  • the opposite-phase sound waves cancel each other out, resulting in an acoustic short circuit, which significantly reduces the low-frequency sound pressure of the speaker and worsens the low-frequency response.
  • the main idea of the present invention is to provide a stretchable film on the diaphragm, use the stretchable film to fill or cover the vibration space, block the leakage channel of sound waves, reduce the sound leakage caused by the vibration space, weaken the acoustic short circuit effect, and improve Low frequency response of the speaker.
  • the stretchable characteristics of the stretchable film are used to weaken the inhibitory effect of the stretchable film on the vibration of the diaphragm, ensuring that the mid- and high-frequency characteristics of the speaker are less affected.
  • the present invention proposes a MEMS speaker, which includes: a diaphragm, one end of the diaphragm It is fixed and has a space for vibration between the other end and the other component; and a stretchable membrane is connected to the diaphragm and the other component respectively, and fills or covers at least part of the space for vibration.
  • the vibration space is used to reduce or eliminate the constraints on the other end of the diaphragm when vibrating.
  • the stretchable film is connected to the diaphragm and another component, and the connection makes the stretchable film stretchable as the diaphragm vibrates.
  • FIG. 2 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention.
  • the MEMS speaker includes two diaphragms 6 .
  • One end of each diaphragm 6 is fixed on the upper end of the corresponding support member 5 to form a fixed end.
  • the other end of each diaphragm 6 is a free end.
  • a vibration space 9 is provided between the free ends of the two diaphragms 6 .
  • the vibration space 9 is specifically a slit. The vibration space 9 can eliminate the constraints on the free end of the diaphragm 6, allowing the diaphragm 6 to vibrate more freely.
  • the two diaphragms 6 may be completely identical or different in terms of shape, size, material, structure, etc.
  • the two diaphragms 6 are exactly the same in terms of shape, size, material and structure.
  • the stretchable membrane 4 is disposed above the two diaphragms 6 and covers the vibration space 9 from above.
  • the lower surface of the stretchable membrane 4 is in complete contact with the upper surfaces of the two diaphragms 6 .
  • the stretchable membrane 4 can block the leakage channel of sound waves, reduce the sound leakage caused by the vibration space, weaken the acoustic short-circuit effect, and improve the low-frequency response of the speaker.
  • the Young's modulus and thickness of the stretchable film 4 meet specific conditions to ensure the stretchability of the stretchable film 4 and reduce its impact on the vibration of the diaphragm 6 , ensuring the mid-to-high frequency (especially mid-frequency) characteristics of the MEMS speaker.
  • the thickness of the stretchable diaphragm 4 does not exceed (ie, is less than or equal to) 500 microns, and the Young's modulus of the stretchable membrane 4 does not exceed 1000 megapascals (MPa).
  • the thickness of stretchable film 4 does not exceed 100 microns, and the Young's modulus of stretchable film 4 does not exceed 100 MPa.
  • the thickness of stretchable film 4 does not exceed 20 microns, and the Young's modulus of stretchable film 4 does not exceed 10 MPa.
  • the thickness of stretchable membrane 4 is no more than 50 times the thickness of diaphragm 6 . In a further example, the thickness of stretchable membrane 4 is no more than 10 times the thickness of diaphragm 6 .
  • Figure 3 is a simulation rendering, showing the sound pressure level frequency response curve of a MEMS speaker without a stretchable film and a MEMS speaker with stretchable films of different Young's modulus in the structure shown in Figure 2.
  • the thickness of the medium stretchable film is 50 microns.
  • the sound pressure level frequency response curve of the speaker has a certain slope in the low frequency band, and the sound pressure level is smaller at lower frequencies, so the low frequency response characteristics are poor.
  • the sound pressure level frequency response curve of the speaker becomes flat in the low frequency band, and the low-frequency response of the speaker is improved.
  • the intermediate frequency part in Figure 3 Comparing a stretchable film with a Young's modulus of 100MPa and a stretchable film with a Young's modulus of 300MPa, 1000MPa, and 2000MPa, it can be found that as the Young's modulus of the stretchable film increases, the mid-frequency sound pressure has Downtrend.
  • the Young's modulus of the stretchable film can be controlled to not exceed 1000MPa to ensure that the mid-frequency sound pressure level does not drop by more than 10dB.
  • the Young's modulus of the stretchable film can be controlled to not exceed 100 MPa to ensure that the mid-frequency sound pressure level does not drop by more than 2dB.
  • the Young's modulus of the stretchable film can be controlled to not exceed 10 MPa to ensure that the mid-frequency sound pressure level does not basically decrease.
  • the stretchable membrane 4 can be made of polymer materials such as rubber, such as silicone rubber or RTV (room-temperature-vulcanizing silicone) rubber, or PDMS.
  • rubber such as silicone rubber or RTV (room-temperature-vulcanizing silicone) rubber, or PDMS.
  • Figure 4A is a simulation rendering, showing the sound pressure level frequency response curve of a MEMS speaker without a stretchable film and a MEMS speaker provided with stretchable films of different thicknesses, where the Young's modulus of the stretchable film is 0.75 MPa.
  • the low frequency response of the speaker can be improved.
  • the mid-frequency band As the thickness of the stretchable film increases, the mid-frequency sound pressure has a downward trend.
  • the thickness of the stretchable film can be controlled to not exceed 100 ⁇ m (or not to exceed 50 ⁇ m, or not to exceed 20 ⁇ m) to ensure that the mid-frequency sound pressure level does not decrease.
  • the high-frequency band As the thickness increases, the resonant frequency of the speaker decreases to a certain extent, but the degree of reduction is limited. The stretchable film has little impact on the high-frequency characteristics of the speaker.
  • Figure 4B is a simulation rendering, illustrating the matching curve of the corresponding stretchable film thickness and Young's modulus when the sound pressure level drops by different decibels.
  • the dotted line represents the matching curve when the sound pressure level drops by 10 decibels.
  • the solid line represents the matching curve when the sound pressure level drops by 5 dB.
  • the Young's modulus and thickness of the stretchable film are both smaller, which can achieve better stretchability and thus better acoustic performance.
  • spaces for vibration such as slits and stretchable films can produce a synergistic effect on the MEMS speaker diaphragm: spaces for vibration such as slits increase vibration displacement by reducing the modulus of the diaphragm, increasing Mid-frequency response, but it brings about the problem of low-frequency deterioration; after adding the stretchable film, the low-frequency response becomes better, while the mid-frequency response basically does not deteriorate.
  • non-stretchable films that is, films whose Young's modulus and/or thickness do not meet specific conditions
  • slits and other vibration spaces reduce the modulus of the diaphragm.
  • the vibration displacement is increased and the mid-frequency response is increased, but it brings about the problem of low-frequency deterioration; after adding a non-stretchable film, the mid-frequency response is severely deteriorated, which offsets the improvement in the mid-frequency response brought by vibration spaces such as slits.
  • FIG 5 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention.
  • the difference from the MEMS speaker in Figure 2 is that the stretchable membrane 4 in Figure 2 is disposed above the two diaphragms 6.
  • the vibration space 9 is covered from above, and the stretchable membrane 4 in Figure 5 is arranged below the two diaphragms 6 to cover the vibration space 9 from below.
  • FIG. 6 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention.
  • the difference from the MEMS speaker in Figure 2 is that the end of the stretchable membrane 4 in Figure 2 is provided with a corresponding fixed end of the diaphragm 6 , the stretchable film 4 completely covers the diaphragm 6 in the cross-sectional length direction of the diaphragm 6, and the end of the stretchable film 4 in Figure 6 is set between the fixed end and the free end of the corresponding diaphragm 6, and can be stretched
  • the stretch film 4 partially covers the diaphragm 6 in the cross-sectional length direction.
  • the structure in Figure 6 can reduce the mass effect introduced by the stretchable film 4, which is conducive to increasing the resonant frequency, improving high-frequency response and thereby increasing the bandwidth.
  • Figure 7 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention.
  • the difference from the MEMS speaker in Figure 6 is that the distance from both ends of the stretchable film 4 to the vibration space 9 in Figure 6 is different. That is, the stretchable film 4 is arranged asymmetrically with respect to the vibration space 9, and the distance from both ends of the stretchable film 4 to the vibration space 9 in Figure 7 is the same, that is, the stretchable film 4 is symmetrical with respect to the vibration space 9 layout.
  • the structure in Figure 7 can reduce the spurious resonance frequency.
  • Figure 8 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention.
  • the stretchable film 4 is provided on the upper surface of the diaphragm 6, which is stretchable.
  • the membrane 4 is located outside the vibration space 9, and in Figure 8, the two ends of the stretchable membrane 4 are respectively fixed on the end surfaces of the free ends of the two diaphragms 6, and the stretchable membrane 4 is located in the vibration space 9.
  • the structure in Figure 8 can reduce the mass effect introduced by the stretchable film 4, improve the blocking effect of the stretchable film 4 on the sound wave leakage channel, and reduce the material consumption of the stretchable film 4.
  • Figure 9 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention.
  • the difference from the MEMS speaker in Figure 7 is that the stretchable film 4 in Figure 2 is overall straight, while the stretchable film 4 in Figure 7 is
  • the stretch film 4 includes a straight part and a convex part, the straight part is provided on the surface of the diaphragm 6 , and the convex part fills the vibration space 9 .
  • the straight part can increase the joint area between the stretchable membrane 4 and the diaphragm 6, and the convex part (or called the filling part) can improve the blocking effect of the stretchable membrane 4 on the sound wave leakage channel. .
  • 10-12 are schematic cross-sectional views of MEMS speakers according to different exemplary embodiments of the present invention, in which the diaphragm and the stretchable membrane have bends.
  • the free ends of the two diaphragms 6 are bent upward, the stretchable membrane 4 is disposed above the two diaphragms 6 , and the portion of the stretchable membrane 4 opposite to the vibration space 9 Also curves upward.
  • the free ends of the two diaphragms 6 are bent downward, the stretchable membrane 4 is disposed above the two diaphragms 6 , and the stretchable membrane 4 is opposite to the vibration space 9 Sections also curve downward.
  • the free ends of the two diaphragms 6 are bent downward, the stretchable membrane 4 is disposed below the two diaphragms 6, and the stretchable membrane 4 is opposite to the vibration space 9 Sections also curve downward.
  • FIG. 13-15 are schematic cross-sectional views of MEMS speakers according to different exemplary embodiments of the present invention, in which a gap exists between the diaphragm and the stretchable membrane.
  • the stretchable membrane 4 is straight, and the free ends of the two diaphragms 6 are bent downward, so that there is a gap between the free ends of the two diaphragms 6 and the diaphragm 4 .
  • the stretchable film 4 and the two diaphragms 6 are both bent upward, but there are differences in the slope changes of the stretchable film 4 and the two diaphragms 6, and the fixation of each diaphragm 6
  • the end and the free end are respectively in contact with the stretchable film 4, and the gap between the stretchable film 4 and the corresponding diaphragm 6 is located between the two ends of the corresponding diaphragm 6.
  • the two diaphragms 6 are straight, and the part of the stretchable diaphragm 4 opposite to the vibration space 9 is bent upward, so that the free ends of the two diaphragms 6 are in contact with the diaphragm 4. There are gaps in between.
  • the existence of the gaps can reduce the mass effect introduced by the stretchable film 4 , which is beneficial to increasing the resonant frequency and increasing the bandwidth.
  • FIG. 16 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which a portion of the stretchable membrane 4 opposite to the vibration space 9 has a curve, and the curved portion is filled in the vibration space 9 .
  • the straight part in Figure 16 can increase the joint area between the stretchable membrane 4 and the diaphragm 6, and the curved part (or called the filling part) can increase the sensitivity of the stretchable membrane 4 to sound waves.
  • the occlusion effect of the leakage channel the curved portion further reduces the equivalent mechanical modulus of the stretchable membrane 4 near the vibration space 9, which is conducive to further reducing the impact of the stretchable membrane 4 on the mid-frequency band performance of the speaker.
  • 17-20 are top schematic diagrams of MEMS speakers according to different exemplary embodiments of the present invention, in which the area projected by the stretchable membrane 4 in the vibration direction is smaller than the total area projected by each diaphragm 6 in the vibration direction, or It is said that the stretchable film 4 does not completely cover the diaphragm 6.
  • the stretchable membrane 4 has an irregular shape, which does not completely cover the diaphragm 6 , but covers the entire vibration space 9 , which can better shield the sound wave leakage channel.
  • the stretchable membrane 4 also completely covers the vibration space 9, and the stretchable membrane 4 continues to extend outward at the vertex corners of the square formed by the four diaphragms 6. Form an extension.
  • the extension part can increase the joint area between the stretchable membrane 4 and the speaker, and improve the joint strength and reliability of the two.
  • the portions of the stretchable film 4 opposite to each diaphragm 6 have a symmetrical pattern, while in the embodiment shown in FIG. 20 , the stretchable film 4 and each diaphragm 6 have a symmetrical pattern.
  • the opposite parts of the diaphragm 6 have asymmetric patterns, so that the resonant frequencies of different diaphragms 6 can be freely configured, thereby increasing the degree of design freedom.
  • the stretchable film 4 since the stretchable film 4 does not completely cover the diaphragm 6 , the stretchable film 4 has a smaller mass, which is beneficial to reducing the mass introduced by the stretchable film 4 effect, thereby increasing the resonant frequency and increasing the bandwidth.
  • FIG 21 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention.
  • the difference from the MEMS speaker in Figure 2 is that the diaphragm 6 in Figure 2 has a single piezoelectric layer structure.
  • the diaphragm 6 includes a structural layer 1, an electrode 3, a piezoelectric layer 2 and another electrode 3 from bottom to top.
  • the diaphragm 6 in Figure 21 has a dual piezoelectric layer structure.
  • the diaphragm 6 includes three electrodes 3 and two piezoelectric layers 2 respectively located between two adjacent electrodes 3.
  • the embodiment of the present invention does not limit the specific structure of the diaphragm 6. Those skilled in the art can set the specific structure of the diaphragm 6 according to actual needs.
  • the number of diaphragms 6 is two or more.
  • the present invention can also be applied in the case of a single cantilever beam diaphragm.
  • 22 and 23 are schematic cross-sectional views of a MEMS speaker according to different exemplary embodiments of the present invention, where the MEMS speaker only includes a single cantilever beam diaphragm.
  • the right end of the diaphragm 6 is fixed to the upper end of the right support member 5 .
  • the left end of the diaphragm 6 is a free end, and a vibration space 9 is formed between the diaphragm 6 and the support member 5 on the left side.
  • the stretchable membrane 4 is provided on the upper surface of the diaphragm 6, and its left end is bent downward to cover the vibration space 9.
  • the MEMS speaker shown in Figure 23 is generally similar to the MEMS speaker shown in Figure 22. The difference is that the left end of the stretchable membrane 4 in Figure 22 is directly fixed to the upper end of the left support 5, while the side support in Figure 23 The upper end of the member 5 is provided with an intermediate medium, and the left end of the stretchable film 4 is fixed to the intermediate medium, so that the stretchable film 4 is indirectly fixedly connected to the support member 5 on the left side.
  • FIGS. 24A and 25A are schematic top views of MEMS speakers according to different exemplary embodiments of the present invention
  • FIGS. 24B and 25B are corresponding cross-sectional schematic views respectively, in which the stretchable film is omitted in the schematic top view.
  • the diaphragm 6 is integrally made or fixedly connected to the coupling structure 7 , so that different diaphragms 6 have portions connected to each other. , the above-mentioned connected parts can transmit force between different diaphragms 6, so that the different diaphragms 6 are coupled to each other.
  • the stretchable film 4 can also be used in such structures. As shown in Figures 24B and 25B, the stretchable film can cover the vibration between the diaphragm 6 and the coupling structure 7 Use space 9 to improve the acoustic response of the loudspeaker.
  • Figure 26 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which an intermediate medium 8 is disposed in the gap between the stretchable film 4 and the diaphragm 6.
  • the intermediate medium 8 is in contact with the stretchable film 4 and the diaphragm 6 respectively.
  • the intermediate medium 8 reduces the contact area between the stretchable film 4 and the diaphragm 6, can reduce the mass effect introduced by the stretchable film 4, and is beneficial to increasing the resonant frequency and increasing the bandwidth.
  • the vibration space 9 is a slit.
  • the vibration space 9 can also be a slit.
  • Using other forms, such as holes or slots, can reduce or eliminate the constraints on the end of the diaphragm when vibrating.
  • Figure 27 is a schematic cross-sectional view of a MEMS speaker according to an exemplary embodiment of the present invention, in which the space 9 for vibration is a groove.
  • the two sides of the groove can be regarded as two diaphragms 6.
  • the left end of the diaphragm 6 on the left side of the groove is fixed, part of the right end is connected to the diaphragm 6 on the right side, and the other part is released from the constraint through the groove, so the left end of the groove is fixed.
  • the right end of the diaphragm 6 on the side can vibrate freely to a certain extent, which is the free end.
  • the left end of the diaphragm 6 on the right side of the groove is the free end.
  • Figure 30 is a simulation rendering, illustrating the sound pressure level frequency response curves of a MEMS speaker provided with a non-stretchable film and a MEMS speaker provided with a stretchable film in the structure of Figure 1C.
  • a sound pressure level simulation comparison chart is shown without using any film, using 15 ⁇ m PDMS (stretchable film) and using 1 ⁇ m Parylene (non-stretchable film). Simulation results show that using membranes can flatten the low-frequency response.
  • 15 ⁇ m PDMS (stretchable film) improves 15dB at low and medium frequencies compared to using 1 ⁇ m Parylene (non-stretchable film).
  • the Young's modulus of Parylene is about 3 GPa.
  • Figures 31 and 32 are respectively the main strain distribution diagrams of a MEMS speaker provided with a non-stretchable film in the structure of Figure 1C and a MEMS speaker provided with a stretchable film.
  • the strain distribution diagram using 1 ⁇ m Parylene (non-stretchable film) is shown in Figure 31, and the strain distribution diagram using 15 ⁇ m PDMS (stretchable film) is shown in Figure 32.
  • Figure 33 is a measured sound pressure chart, illustrating the sound pressure level frequency response of a MEMS speaker without 15 ⁇ m PDMS (stretchable film) and a MEMS speaker with 15 ⁇ m PDMS (stretchable film) in the structure of Figure 1C curve.
  • the test results show that the sound pressure level at the low frequency has increased by 15dB; the frequency response of the low frequency has been significantly improved; the first half of the mid-frequency has improved, but the second half has not deteriorated; the change of the high frequency is small, and the bandwidth Reduction limited.
  • 28A-28K are illustrative illustrations of wafer-level fabrication in accordance with an exemplary embodiment of the present invention.
  • Step 1 Form a MEMS speaker wafer, and the speaker wafer is provided with multiple MEMS speakers.
  • Step 2 Set stretchable films for multiple MEMS speakers on the speaker wafer at the same time.
  • Step three perform cutting to form multiple MEMS speakers with stretchable membranes.
  • step one is explained below with reference to the attached figure:
  • a basic structure including SOI bottom silicon 500, SOI silicon oxide B, SOI top silicon 100 and the first electrode layer 310 from top to bottom.
  • a piezoelectric layer 200 is provided on top of the structure in the previous step.
  • a second electrode layer 320 is provided on top of the structure in the previous step.
  • the structure in the previous step is etched to form a slit 640, and the slit 640 ends at SOI silicon oxide B.
  • the SOI bottom silicon 500 (see FIG. 28A) is etched to form a cavity 900.
  • Unetched SOI bottom silicon 500 (see Figure 28A) forms the support for the MEMS speaker.
  • the SOI silicon oxide B (see Figure 28A) is etched to release the diaphragm to form a MEMS speaker wafer.
  • each diaphragm and the corresponding support member form a corresponding MEMS speaker.
  • step two The implementation process of step two is explained below with reference to the attached figure:
  • the stretchable film wafer includes SOI bottom silicon 500 (ie, auxiliary substrate), sacrificial layer C and PDMS layer 400 (ie, stretchable film layer), where , the sacrificial layer C is between the SOI bottom silicon 500 and the PDMS layer 400.
  • the stretchable film wafer is bonded to the speaker wafer, so that the PDMS layer 400 is bonded to the speaker film layer or diaphragm layer in the speaker wafer.
  • the sacrificial layer C (see FIG. 28I ) is released to remove the SOI bottom silicon 500 (see FIG. 28I ) to expose the PDMS layer 400 .
  • step three The implementation process of step three is explained below with reference to the attached figure:
  • 29G-29I are a series of cross-sectional schematic diagrams illustrating a process flow for preparing MEMS speakers at the wafer level according to another exemplary embodiment of the present invention.
  • the process flow in this embodiment is generally similar to the process flow in the previous embodiment. The difference lies in the steps of setting the stretchable film and finally obtaining The structure of the MEMS speaker.
  • the step of setting the stretchable film includes:
  • a PDMS solution ie, a solution of a material for a stretchable film
  • a PDMS layer 400 i.e., stretch film layer
  • the stretchable film in Figure 28K is straight and covers the space for vibration from above, and the stretchable film in Figure 29I includes protrusions, and the protrusions fill the space for vibration.
  • a MEMS speaker including:
  • a diaphragm one end of which is fixed and a space for vibration is provided between the other end and another component;
  • a stretchable membrane is connected to the diaphragm and the other component respectively, and fills or covers at least part of the vibration space.
  • the other component includes another diaphragm, one end of the other diaphragm is fixed, and the vibration space is provided between the other end and the other end of the diaphragm.
  • Both ends of the stretchable film are respectively fixed to the same side surface of the diaphragm and the other diaphragm, and the stretchable film covers the vibration space from one side of the vibration space .
  • One end of the stretchable film is disposed at one end of the diaphragm, and the other end of the stretchable film is disposed at one end of the other diaphragm.
  • One end of the stretchable membrane includes an extension beyond one end of the diaphragm, and the other end of the stretchable membrane includes an extension beyond one end of the other diaphragm.
  • One end of the stretchable membrane is disposed between one end and the other end of the diaphragm;
  • the other end of the stretchable membrane is disposed between one end and the other end of the other diaphragm.
  • the distance from one end and the other end of the stretchable film to the vibration space is different.
  • the distance from one end and the other end of the stretchable film to the vibration space is the same.
  • the surface of the stretchable film facing the vibration space is in complete contact with the same-side surfaces of the diaphragm and the other diaphragm respectively.
  • a portion of the stretchable film opposite to the vibration space has a curvature.
  • the gap is located between one end and the other end of the diaphragm; and/or
  • the gap is located between one end and the other end of the other diaphragm.
  • the gap is located at the other end of the diaphragm; and/or
  • the gap is located at the other end of the other diaphragm.
  • the stretchable membrane is straight, and the other end of the diaphragm and/or the other end of the other diaphragm has a bend;
  • the diaphragm and the other diaphragm are straight, and the portion of the stretchable diaphragm opposite to the vibration space has a curve; or
  • the other end of the diaphragm and/or the other end of the other diaphragm has a bend, and a portion of the stretchable membrane opposite to the vibration space has a bend.
  • An intermediate medium is provided in the gap, and the intermediate medium is in contact with the stretchable film and the diaphragm respectively, or the intermediate medium is in contact with the stretchable film and the other diaphragm respectively.
  • the projected area of the stretchable membrane in the vibration direction is smaller than that of the diaphragm and the other diaphragm in the vibration direction.
  • the total area projected in the moving direction is smaller than that of the diaphragm and the other diaphragm in the vibration direction.
  • the portion of the stretchable film opposite the diaphragm and the portion of the stretchable film opposite the other diaphragm have symmetrical patterns.
  • the portion of the stretchable film opposite the diaphragm and the portion of the stretchable film opposite the other diaphragm have an asymmetric pattern.
  • Two ends of the stretchable film are respectively fixed to opposite end surfaces of the diaphragm and the other diaphragm.
  • Both ends of the stretchable film are respectively fixed to the same side surface of the diaphragm and the other diaphragm, and a protrusion is provided on the stretchable film at a position opposite to the vibration space, so The protrusion is at least partially filled in the vibration space.
  • the other component includes a second support member, one end of the diaphragm is fixed on the first support member, and the vibration space is provided between the other end and the upper end of the second support member.
  • the portion of the stretchable film opposite to the vibration space is straight; or
  • a portion of the stretchable film opposite to the vibration space has a curvature toward the vibration space.
  • the other component includes another diaphragm, one end of the other diaphragm is fixed and the vibration space is provided between the other end and the other end of the diaphragm, the diaphragm and the other diaphragm are The diaphragms are coupled to each other in a locally connected manner.
  • the space for vibration includes slits, holes or grooves.
  • the thickness of the stretchable diaphragm does not exceed 500 microns.
  • the stretchable film has a Young's modulus of no more than 1000 MPa.
  • the thickness of the stretchable film does not exceed 100 microns.
  • the stretchable film has a Young's modulus of no more than 100 MPa.
  • the thickness of the stretchable film does not exceed 20 microns.
  • the stretchable film has a Young's modulus of no more than 10 MPa.
  • the thickness of the stretchable film does not exceed 50 times the thickness of the diaphragm. Further, the thickness of the stretchable film No more than 10 times the thickness of the diaphragm; or
  • Materials for stretchable membranes include silicone rubber or RTV rubber or PDMS.
  • a method of manufacturing a MEMS speaker including the steps:
  • the speaker wafer is provided with multiple MEMS speakers, and each speaker includes a corresponding support member;
  • Cutting is performed to form multiple MEMS speakers with stretchable membranes.
  • step of setting the stretchable film includes:
  • the stretchable film wafer includes a stretchable film layer, a sacrificial layer and an auxiliary substrate, the sacrificial layer is between the stretchable film layer and the auxiliary substrate;
  • the sacrificial layer is released to remove the auxiliary substrate to expose the stretchable film layer.
  • step of forming the MEMS speaker wafer includes:
  • a speaker wafer basic structure which provides a basic structure including SOI bottom silicon, SOI silicon oxide, SOI top silicon, a first electrode layer, a piezoelectric layer, and a second electrode layer from top to bottom;
  • the SOI silicon oxide is etched to penetrate the plurality of etched portions to release the diaphragm, thereby forming a MEMS speaker wafer.
  • step of setting the stretchable film includes:
  • the coated solution is allowed to solidify to form a stretchable film layer.
  • the steps of forming a MEMS speaker wafer include: forming multiple vibration spaces on one side of the speaker wafer based on the MEMS process;
  • the solution fills the plurality of vibration spaces
  • the solution in the vibration space is also solidified.
  • An electronic device including the speaker according to any one of 1-28 or the speaker manufactured according to the method according to any one of 29-33.

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Abstract

本发明涉及一种MEMS扬声器、一种MEMS扬声器的制造方法以及包括其的电子设备。该MEMS扬声器包括：振膜，振膜的一端固定且另一端与另一部件之间设置有振动用空间；可拉伸膜，分别与振膜和另一部件连接，且填充或者覆盖至少部分振动用空间。本发明还涉及一种MEMS扬声器的制造方法以及一种电子设备。

Description

具有可拉伸膜的MEMS扬声器、其制造方法以及包括其的电子设备 技术领域
本发明的实施例涉及半导体领域，尤其涉及一种具有可拉伸膜的MEMS扬声器、其制造方法以及包括其的电子设备。
背景技术
MEMS(Micro-electro Mechanical Systems，微机电系统)扬声器是一种将电信号转变为声信号的微型换能器，其核心组件(例如执行器/驱动器、振膜、热声膜等)利用MEMS技术在半导体材料上制造而成。MEMS扬声器按照工作原理可以分为压电式、电动式、静电式和热声式。
压电式MEMS扬声器的工作原理是使用压电薄膜作为换能元件，当施加电压时会发生变形。这种机械偏转使周围的空气发生位移并产生声波。压电式MEMS扬声器一个主要优点是它与半导体工艺的兼容性，这意味着它可以以低成本大规模和极小尺寸生产。除了尺寸之外，压电式MEMS扬声器还具有极低的功率以及出色的音频质量。压电式MEMS扬声器也可以构建在与放大器相同的PCB基板上，从而节省电路板空间。
悬臂梁式振膜是压电式MEMS扬声器中常用的振膜结构。带有狭缝的悬臂梁振膜结构如图1A、图1B和图1C所示，图1A为已知的多个悬臂梁振膜的俯视图，图1B为图1A中的结构在A-A剖切面的剖视图。如图1A所示，该MEMS扬声器包括四个振膜，即振膜60、振膜61、振膜62和振膜63。每个振膜均为三角形，其中一端固定，例如振膜60的一端固定在支撑件51上，其余两端为自由端。相邻两个振膜的相对的自由端之间设置有狭缝，例如振膜60和振膜61的相对的自由端之间设置有狭缝64。狭缝能够减少振膜在振动时受到的约束。图1C所示的悬臂梁振膜为八瓣结构的示意图，其中60为八个振膜中的其中一个振膜，64为振膜之间的狭缝，51为振膜的支撑层(用于机械支撑或固定振膜 边缘)。然而，如图1B所示，振膜61或者振膜63一侧(例如上侧)的声波会通过狭缝绕射至另一侧(例如下侧)，引起声短路现象，导致扬声器低频频段的响应降低，频响曲线平坦度变差。
发明内容
为缓解或解决现有技术中的上述问题的至少一个方面，提出本发明。
根据本发明的实施例的一个方面，提出了一种MEMS扬声器，包括：振膜，振膜的一端固定且另一端与另一部件之间设置有振动用空间；可拉伸膜，分别与振膜和另一部件连接，且填充或者覆盖至少部分振动用空间。
根据本发明的实施例的一个方面，提出了一种MEMS扬声器的制造方法，包括步骤：形成MEMS扬声器晶圆，扬声器晶圆设置有多个MEMS扬声器；在扬声器晶圆上为所述多个MEMS扬声器同时设置可拉伸膜；执行切割，以形成多个带有可拉伸膜的MEMS扬声器。
本发明的实施例也涉及一种电子设备，包括上述的MEMS扬声器。
附图说明
以下描述与附图可以更好地帮助理解本发明所公布的各种实施例中的这些和其他特点、优点，图中相同的附图标记始终表示相同的部件，其中：
图1A为已知的多个悬臂梁振膜的俯视示意图；
图1B为图1A中的结构在A-A剖切的截面示意图；
图1C为已知的另外的多个悬臂梁振膜的俯视示意图；
图2为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图；
图3为仿真效果图，示例性示出了无可拉伸膜的MEMS扬声器以及设置有不同杨氏模量的可拉伸膜的MEMS扬声器的声压级频率响应曲线，其中可拉伸膜的厚度为50微米；
图4A为仿真效果图，示例性示出了无可拉伸膜的MEMS扬声器以及设置有不同厚度的可拉伸膜的MEMS扬声器的声压级频率响应曲线，其中可拉伸膜的杨氏模量为0.75兆帕；
图4B为仿真效果图，示例性示出了声压级下降不同分贝时，对应的可拉伸膜厚度和杨氏模量的配合曲线，其中虚线代表声压级下降10分贝时的配合曲线， 实线代表声压级下降5分贝时的配合曲线；
图5为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中可拉伸膜设置在振膜的下方；
图6为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中可拉伸膜的端部设置在振膜的两端之间，且相对于振动用空间非对称布置；
图7为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中可拉伸膜的端部设置在振膜的两端之间，且相对于振动用空间对称布置；
图8为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中可拉伸膜填充在振动用空间中；
图9为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中可拉伸膜一部分设置在振膜表面，另一部分填充在振动用空间中；
图10-图12为根据本发明的不同示例性实施例的MEMS扬声器的截面示意图，其中振膜和可拉伸膜具有弯曲；
图13-图15为根据本发明的不同示例性实施例的MEMS扬声器的截面示意图，其中振膜和可拉伸膜之间存在空隙；
图16为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中可拉伸膜的与振动用空间相对的部分具有弯曲；
图17-图20为根据本发明的不同示例性实施例的MEMS扬声器的俯视示意图，其中可拉伸膜没有将振膜全部覆盖；
图21为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中振膜为双压电层结构；
图22和图23为根据本发明的不同示例性实施例的MEMS扬声器的截面示意图，其中MEMS扬声器只包括单个的悬臂梁振膜；
图24A和图25A为根据本发明的不同示例性实施例的MEMS扬声器的俯视示意图，图24B和图25B分别为相应的截面示意图，其中不同的振膜以部分连接的方式相互耦合；
图26为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中可拉伸膜和振膜之间的空隙内设置有中间介质；
图27为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中振动用空间为凹槽；
图28A-图28K为根据本发明的一个示例性实施例的示例性示出制备MEMS扬声器的工艺流程的一系列截面示意图；
图29G-图29I为根据本发明的另一个示例性实施例的示例性示出制备MEMS扬声器的工艺流程的一系列截面示意图；
图30为仿真效果图，示例性示出了图1C的结构中设置不可拉伸膜的MEMS扬声器以及设置可拉伸膜的MEMS扬声器的声压级频率响应曲线；
图31和图32分别为在图1C的结构中设置不可拉伸膜的MEMS扬声器以及设置可拉伸膜的MEMS扬声器的主应变分布图；
图33为声压实测图，示例性示出了图1C的结构中不设置15μm PDMS(可拉伸膜)的MEMS扬声器以及设置15μm PDMS(可拉伸膜)的MEMS扬声器的声压级频率响应曲线。
具体实施方式
下面通过实施例，并结合附图，对本发明的技术方案作进一步具体的说明。在说明书中，相同或相似的附图标号指示相同或相似的部件。下述参照附图对本发明实施方式的说明旨在对本发明的总体发明构思进行解释，而不应当理解为对本发明的一种限制。发明的一部分实施例，而并不是全部的实施例。基于本发明中的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本发明保护的范围。
本发明中的附图标记说明如下：
51：已知的MEMS扬声器中的支撑件；
60-63：已知的MEMS扬声器中的振膜；
64：已知的MEMS扬声器中的狭缝；
1：结构层，例如参见图2，其材料例如是硅、二氧化硅等，也可以用压电层或电极的材料充当，在可选的实施例中，也可以不采用该层；
2：压电层，例如参见图2，其材料例如是氮化铝(AlN)、钪掺杂氮化铝(AlScN)、锆钛酸铅(化学式为Pb(Tix、Zr1-x)O3，缩写为PZT)、氧化锌(化学式为ZnO)、铌酸锂(LiNbO3)等；
3：电极，例如参见图2，其材料例如是钼、铂、金等金属；
4：可拉伸膜，例如参见图2，其为杨氏模量和厚度满足特定条件的薄膜， 例如可以采用橡胶等高分子材料，例如是硅橡胶或RTV(room-temperature-vulcanizing silicone)橡胶，或者PDMS(Polydimethylsiloxane，聚二甲基硅氧烷)等，可拉伸膜分别与振膜(参见下文描述)的一端和另一部件(例如另一振膜或者下文描述的支撑件)连接，上述连接使得可拉伸膜在振膜振动时被拉伸；
5：支撑件，例如参见图2，用于支撑振膜，材料例如是硅等；
6：振膜，例如参见图2，其适于通过自身振动带动空气振动以发出声音，包括结构层1(如有)、压电层2和电极3等组成部分；
7：耦合结构，例如参见图24A、图24B、图25A和图25B；
8：中间介质，例如参见图26；
9：振动用空间，例如参见图2，为振膜振动提供条件的空间，或者为减少或者消除振膜的端部在振动时受到的约束而设置的空间，形式例如是狭缝、孔或者槽等；
100：SOI(Silicon-On-Insulator，绝缘衬底上的硅)顶硅，例如参见图28A；
200：压电层，同上文对压电层的描述，例如参见图28B；
310：第一电极层，同上文对电极的描述，例如参见图28A；
320：第二电极层，同上文对电极的描述，例如参见图28C；
400：PDMS层，例如参见图28G；
500：SOI底硅，或者辅助基底，例如参见图28A；
640：狭缝，例如参见图28D；
900、空腔，例如参见图28E；
B：SOI氧化硅，例如参见图28A；
C：牺牲层，例如参见图28G。
在例如图1A、图1B以及图1C示出的带有狭缝的悬臂梁振膜结构中，振膜一侧的部分声波(尤其是低频部分)会通过狭缝绕射至振膜的另一侧，导致反相声波相互抵消，发生声短路现象，使得扬声器的低频声压显著下降，低频响应变差。本发明的主要思路是在振膜上设置可拉伸膜，利用可拉伸膜填充或者覆盖振动用空间，遮挡声波的泄露通道，减少振动用空间带来的声音泄露，削弱声短路效应，提高扬声器的低频响应。同时，利用可拉伸膜的可拉伸特性，减弱可拉伸膜对振膜振动的抑制作用，保证扬声器的中高频特性受到的影响较小。
参见附图，本发明提出了一种MEMS扬声器，其包括：振膜，振膜的一端 固定且另一端与另一部件之间设置有振动用空间；和可拉伸膜，分别与振膜和另一部件连接，且填充或者覆盖至少部分振动用空间。
在本发明中，振动用空间用于减少或者消除振膜的另一端在振动时受到的约束。在本发明中，可拉伸膜与振膜以及另一部件连接，该连接使得可拉伸膜随着振膜的振动而可拉伸。
图2为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图。在图2所示的实施例中，MEMS扬声器包括两个振膜6。每个振膜6的一端固定在对应的支撑件5的上端，形成固定端。每个振膜6的另一端为自由端。两个振膜6的自由端之间设置有振动用空间9。振动用空间9具体为狭缝。振动用空间9能够消除振膜6的自由端所受到的约束，使得振膜6能够更加自由的振动。
在图2所示的实施例中，两个振膜6在形状、尺寸、材料和结构等方面可以完全相同，也可以存在差异。可选的，在图2所示的实施例中，两个振膜6在形状、尺寸、材料和结构等方面完全相同。
在图2所示的实施例中，可拉伸膜4设置在两个振膜6的上方且从上方覆盖振动用空间9。可拉伸膜4的下表面与两个振膜6的上表面完全接触。如本领域技术人员能够理解的，可拉伸膜4能够遮挡声波的泄露通道，减少振动用空间带来的声音泄露，削弱声短路效应，提高扬声器的低频响应。
在图2所示的实施例中，可拉伸膜4的杨氏模量和厚度满足特定的条件，以保证可拉伸膜4的可拉伸特性，减小其对振膜6振动的影响，保证MEMS扬声器的中高频(尤其是中频)特性。在一个示例中，可拉伸振膜4的厚度不超过(即小于或者等于)500微米，且可拉伸膜4的杨氏模量不超过1000兆帕(MPa)。在一个进一步的示例中，可拉伸膜4的厚度不超过100微米，且可拉伸膜4的杨氏模量不超过100兆帕。在另一个进一步的示例中，可拉伸膜4的厚度不超过20微米，且可拉伸膜4的杨氏模量不超过10兆帕。
在一些实施方式中，当可拉伸膜4的杨氏模量不超过1000兆帕时，可以通过限定可拉伸膜4与振膜6之间的厚度的关系，保证可拉伸膜4对振膜6的振动产生较小影响。在一个示例中，可拉伸膜4的厚度不超过振膜6的厚度的50倍。在一个进一步的示例中，可拉伸膜4的厚度不超过振膜6的厚度的10倍。
图3为仿真效果图，示出了无可拉伸膜的MEMS扬声器以及图2所示结构中设置有不同杨氏模量的可拉伸膜的MEMS扬声器的声压级频率响应曲线，其 中可拉伸膜的厚度为50微米。
首先观察图3中的低频部分。在无可拉伸膜的情况下，扬声器的声压级频响曲线在低频段具有一定的倾斜，并且频率较低时声压级较小，因此低频响应特性较差。在设置了可拉伸膜的情况下，无论可拉伸膜的杨氏模量取何种数值，扬声器的声压级频率响应曲线在低频段都变得平坦，扬声器的低频响应得到改善。
其次观察图3中的中频部分。将杨氏模量为100Mpa的可拉伸膜与杨氏模量为300MPa、1000MPa、2000MPa的可拉伸膜进行对比，可以发现随着可拉伸膜的杨氏模量增加，中频声压具有下降趋势。可选的，可以通过控制可拉伸膜的杨氏模量不超过1000MPa，保证中频声压级的下降不超过10dB。进一步的，可以通过控制可拉伸膜的杨氏模量不超过100兆帕，保证中频声压级的下降不超过2dB。更进一步的，可以通过控制可拉伸膜的杨氏模量不超过10兆帕，保证中频声压级基本不下降。
最后观察图3中的高频部分，加入可拉伸模后，扬声器的谐振频率虽然有一定的降低，但降低程度有限，即可拉伸膜对扬声器高频特性带来的影响较小。
在一个示例中，可拉伸膜4可以采用橡胶等高分子材料，例如是硅橡胶或RTV(room-temperature-vulcanizing silicone)橡胶，或者PDMS
(Polydimethylsiloxane，聚二甲基硅氧烷)等。上述材料的杨氏模量均不超过10MPa，因此能够达到或者优于图3中10MPa曲线对应的声学性能改善效果。
图4A为仿真效果图，示出了无可拉伸膜的MEMS扬声器以及设置有不同厚度的可拉伸膜的MEMS扬声器的声压级频率响应曲线，其中可拉伸膜的杨氏模量为0.75兆帕。
如图4A所示。对于低频段，加入可拉伸膜后，扬声器的低频响应得得到改善。对于中频段，随着可拉伸膜厚度增加，中频声压具有下降趋势。可以通过控制可拉伸膜的厚度不超过500μm，保证中频声压级的下降不超过10dB。进一步的，可以通过控制可拉伸膜的厚度不超过100μm(或者不超过50μm，又或者不超过20μm)，保证中频声压级不下降。对于高频段，随着厚度的增加，扬声器的谐振频率虽然有一定的降低，但降低程度有限，即可拉伸膜对扬声器高频特性带来的影响较小。
图4B为仿真效果图，示例性示出了声压级下降不同分贝时，对应的可拉伸膜厚度和杨氏模量的配合曲线，其中虚线代表声压级下降10分贝时的配合曲线， 实线代表声压级下降5分贝时的配合曲线。从图4B中可以看出，下降同样的声压级，可拉伸膜的杨氏模量越小，可拉伸膜的厚度可以相应越厚；同理，下降同样的声压级，可拉伸膜的厚度越薄，可拉伸膜的杨氏模量可以相应越大。可拉伸膜的杨氏模量和厚度可以按照上述规律相互配合，保证可拉伸膜的可拉伸性。
在一个示例中，可拉伸膜的杨氏模量和厚度均取较小值，能够实现较好的可拉伸性，进而实现较好的声学性能。
在本发明的实施例中，狭缝等振动用空间和可拉伸膜可以在MEMS扬声器振膜上产生协同效应：狭缝等振动用空间通过减小振膜模量提高了振动位移，增加了中频响应，但带来了低频恶化的问题；加入可拉伸膜后，低频响应变好，同时中频响应基本没有恶化。相反，非可拉伸膜(即杨氏模量和/或厚度不满足特定条件的薄膜)则无法与狭缝等振动用空间产生协同效应：狭缝等振动用空间通过减小振膜模量提高了振动位移，增加了中频响应，但带来了低频恶化的问题；加入非可拉伸膜后，中频响应恶化严重，抵消了狭缝等振动用空间带来的中频响应提高。
图5为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其与图2中MEMS扬声器的区别在于，图2中的可拉伸膜4设置在两个振膜6的上方，从上方覆盖振动用空间9，而图5中的可拉伸膜4设置在两个振膜6的下方，从下方覆盖振动用空间9。上述两种方式均可实现本发明实施例的发明目的。
图6为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其与图2中MEMS扬声器的区别在于，图2中可拉伸膜4的端部设置对应的振膜6的固定端，可拉伸膜4在振膜6截面长度方向将振膜6全部覆盖，而图6中可拉伸膜4的端部设置在对应的振膜6的固定端和自由端之间，可拉伸膜4在振膜6截面长度方向将振膜6部分覆盖。图6中的结构相对于图2中的结构，能够减少可拉伸膜4引入的质量效应，有利于提高谐振频率，提升高频响应从而增加带宽。
图7为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其与图6中MEMS扬声器的区别在于，图6中可拉伸膜4的两端到振动用空间9的距离不同，即可拉伸膜4相对于振动用空间9非对称布置，而图7中可拉伸膜4的两端到振动用空间9的距离相同，即可拉伸膜4相对于振动用空间9对称布置。图7中的结构相对于图6中的结构，可以减少寄生谐振频率。
图8为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其与图2中MEMS扬声器的区别在于，图2中可拉伸膜4设置在振膜6的上表面，可拉伸膜4位于振动用空间9外，而图8中可拉伸膜4的两端分别固定在两个振膜6的自由端的端面，可拉伸膜4位于振动用空间9内。图8中的结构相对于图2中的结构，可以减少可拉伸膜4引入的质量效应，提高可拉伸膜4对声波泄露通道的遮挡效果以及减少可拉伸膜4的材料消耗。
图9为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其与图7中MEMS扬声器的区别在于，图2中可拉伸膜4是整体平直的，而图7中的可拉伸膜4包括平直部分和凸起部分，其中平直部分设置在振膜6的表面，凸起部分填充在振动用空间9内。对于图7中结构，平直部分能够增大可拉伸膜4与振膜6的接合面积，凸起部分(或者称其为填充部分)能够提高可拉伸膜4对声波泄露通道的遮挡效果。
图10-图12为根据本发明的不同示例性实施例的MEMS扬声器的截面示意图，其中，振膜和可拉伸膜具有弯曲。
在图10所示的实施例中，两个振膜6的自由端向上弯曲，可拉伸膜4设置在两个振膜6的上方，且可拉伸膜4与振动用空间9相对的部分也向上弯曲。
在图11所示的实施例中，两个振膜6的自由端向下弯曲，可拉伸膜4设置在两个振膜6的上方，且可拉伸膜4与振动用空间9相对的部分也向下弯曲。
在图12所示的实施例中，两个振膜6的自由端向下弯曲，可拉伸膜4设置在两个振膜6的下方，且可拉伸膜4与振动用空间9相对的部分也向下弯曲。
在振膜6的制造或者使用过程中，其内部会产生应力，导致振膜6弯曲，从而可能呈现如图10-图12所示的结构。
图13-图15为根据本发明的不同示例性实施例的MEMS扬声器的截面示意图，其中振膜和可拉伸膜之间存在空隙。
在图13所示的实施例中，可拉伸膜4是平直的，两个振膜6的自由端向下弯曲，从而两个振膜6的自由端与振膜4之间存在空隙。
在图14所示的实施例中，可拉伸膜4和两个振膜6均向上弯曲，但是可拉伸膜4和两个振膜6的斜率变化存在区别，每个振膜6的固定端和自由端分别与可拉伸膜4接触，可拉伸膜4和对应的振膜6之间的空隙位于对应的振膜6的两端之间。
在图15所示的实施例中，两个振膜6是平直的，可拉伸膜4与振动用空间9相对的部分向上弯曲，从而两个振膜6的自由端与振膜4之间存在空隙。
在图13-图15所示的实施例中，空隙的存在能够减小可拉伸膜4引入的质量效应，有利于提高谐振频率，增加带宽。
图16为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中可拉伸膜4的与振动用空间9相对的部分具有弯曲，该弯曲部分填充在振动用空间9中。与图7中的结构类似，图16中的平直部分能够增大可拉伸膜4与振膜6的接合面积，弯曲部分(或者称其为填充部分)能够提高可拉伸膜4对声波泄露通道的遮挡效果。此外，弯曲部分使得可拉伸膜4在振动用空间9附近的等效机械模量进一步减小，有利于进一步减小可拉伸膜4对扬声器的中频段性能造成的影响。
图17-图20为根据本发明的不同示例性实施例的MEMS扬声器的俯视示意图，其中可拉伸膜4在振动方向上投影的面积小于各个振膜6在振动方向上投影的总面积，或者说，可拉伸膜4没有将振膜6全部覆盖。
在图17所示的实施例中，四个三角形的振膜6拼成正方形，可拉伸膜4为圆形，覆盖仅每个振膜6的靠近正方形中心的部分。
在图18所示的实施例中，可拉伸膜4为不规则形状，其没有将振膜6全部覆盖，但是将振动用空间9全部覆盖，这样能够更好地遮蔽声波泄露通道。
在图19所示的实施例中，可拉伸膜4同样将振动用空间9全部覆盖，并且可拉伸膜4在四个振膜6所拼成的正方形的顶角处继续向外延伸，形成延伸部分。延伸部分可以增加可拉伸膜4与扬声器的接合面积，提高二者的接合强度和接合可靠性。
在图17-图19所示的实施例中，可拉伸膜4与各个振膜6相对的部分具有对称的图案，而在图20所示的实施例中，可拉伸膜4与各个振膜6相对的部分具有非对称的图案，这样可以自由配置不同振膜6的谐振频率，从而提高设计自由度。
在图17-图20所示的实施例中，由于可拉伸膜4没有将振膜6全部覆盖，因此可拉伸膜4具有更小的质量，有利于减少可拉伸膜4引入的质量效应，从而提高谐振频率，增加带宽。
图21为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图， 其与图2中MEMS扬声器的区别在于，图2中的振膜6为单压电层结构，振膜6自下而上依次包括结构层1、电极3、压电层2和另一电极3，而图21中的振膜6为双压电层结构，振膜6包括三个电极3以及分别位于相邻两个电极3之间的两个压电层2。本发明实施例对振膜6的具体结构不做限定，本领域技术人员可以根据实际需求设置振膜6的具体结构。
在前述实施例中，振膜6的数目为两个或者两个以上。除此之外，本发明还可以应用在单个悬臂梁振膜的情形中。
图22和图23为根据本发明的不同示例性实施例的MEMS扬声器的截面示意图，其中MEMS扬声器只包括单个的悬臂梁振膜。
在图22所示的实施例中，振膜6的右端固定在右侧的支撑件5的上端。振膜6的左端为自由端，且与左侧的支撑件5之间形成振动用空间9。可拉伸膜4设置在振膜6的上表面，其左端向下弯曲并覆盖振动用空间9。
图23所示的MEMS扬声器与图22所示的MEMS扬声器大体类似，区别在于图22中可拉伸膜4的左端直接固定至左侧的支撑件5的上端，而图23中的侧的支撑件5的上端设置有中间介质，可拉伸膜4的左端固定至该中间介质，从而可拉伸膜4与左侧的支撑件5间接地固定连接。
图24A和图25A为根据本发明的不同示例性实施例的MEMS扬声器的俯视示意图，图24B和图25B分别为相应的截面示意图，其中，俯视示意图中省略了可拉伸膜。
在图24A和图24B所示的实施例，以及图25A和图25B所示的实施例中，振膜6与耦合结构7一体制成或者固定连接，从而不同的振膜6具有彼此连接的部分，上述彼此连接的部分能够在不同的振膜6之间传递力的作用，使得不同的振膜6相互耦合。如本领域技术人员所能够理解的，可拉伸膜4同样可以应用在此类结构中，如图24B和图25B所示，可拉伸膜能够覆盖振膜6与耦合结构7之间的振动用空间9，从而改善扬声器的声学响应。
图26为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中可拉伸膜4和振膜6之间的空隙内设置有中间介质8。中间介质8分别与可拉伸膜4和振膜6接触。中间介质8减小了可拉伸膜4和振膜6的接触面积，能够减少可拉伸膜4引入的质量效应，有利于提高谐振频率，增加带宽。
在前述实施例中，振动用空间9为狭缝，除此之外，振动用空间9还可以采 用其他形式，例如孔或者槽等，能起到减少或者消除振膜的端部在振动时受到的约束即可。
图27为根据本发明的一个示例性实施例的MEMS扬声器的截面示意图，其中振动用空间9为凹槽。凹槽的两侧可视为两个振膜6，凹槽左侧的振膜6的左端固定，右端的一部分与右侧的振膜6连接，另一部分通过凹槽释放约束，所以凹槽左侧的振膜6的右端能够在一定程度上自由振动，即为自由端。类似的，凹槽右侧的振膜6的左端为自由端。
图30为仿真效果图，示例性示出了图1C的结构中设置不可拉伸膜的MEMS扬声器以及设置可拉伸膜的MEMS扬声器的声压级频率响应曲线。图30中，示出了不使用任何膜、使用15μm PDMS(可拉伸膜)和使用1μm Parylene(非可拉伸膜)的声压级仿真对比图。仿真结果表明，使用膜可以使低频响应变平。此外，使用15μm PDMS(可拉伸膜)比使用1μm Parylene(非可拉伸膜)在低频和中频提高了15dB。Parylene的杨氏模量约为3 GPa，即使其厚度很薄，也不属于可拉伸膜，因此使用1μm Parylene后的MEMS扬声器低频和中频响应均大幅下降，无法与狭缝等振动用空间形成协同效应。
图31和图32分别为在图1C的结构中设置不可拉伸膜的MEMS扬声器以及设置可拉伸膜的MEMS扬声器的主应变分布图。使用1μm Parylene(非可拉伸膜)的应变分布图如图31所示，使用15μm PDMS(可拉伸膜)的应变分布图如图32所示。对比图31和图32可以看出，在低频处，使用15μm PDMS(可拉伸膜)是使用1μm Parylene(非可拉伸膜)的应变值的3倍，因为越大的应变值意味着可拉伸模/非可拉伸膜对振膜的振动限制越小，允许振膜产生更大的位移，而大的位移代表更高的声压级，因此，使用15μm PDMS(可拉伸膜)比使用1μm Parylene(非可拉伸膜)更优。
图33为声压实测图，示例性示出了图1C的结构中不设置15μm PDMS(可拉伸膜)的MEMS扬声器以及设置15μm PDMS(可拉伸膜)的MEMS扬声器的声压级频率响应曲线。如图33所示，测试结果表明，低频处声压级上升了15dB；低频的频响都有明显的改善；中频的前半部分有改善，后半部分未恶化；高频的变化较小，带宽减少有限。
下面示例性说明根据本发明的MEMS扬声器的制备工艺。
图28A-图28K为根据本发明的一个示例性实施例的示例性示出晶圆级制备 MEMS扬声器的工艺流程的一系列截面示意图。该工艺流程包括以下步骤：
步骤一、形成MEMS扬声器晶圆，扬声器晶圆设置有多个MEMS扬声器。
步骤二、在扬声器晶圆上为多个MEMS扬声器同时设置可拉伸膜。
步骤三，执行切割，以形成多个带有可拉伸膜的MEMS扬声器。
以下结合附图，说明步骤一的实施过程：
如图28A所示，提供基础结构，自上而下依次包括SOI底硅500、SOI氧化硅B、SOI顶硅100和第一电极层310。
如图28B所示，在上一步中结构的最上方设置压电层200。
如图28C所示，在上一步中结构的最上方设置第二电极层320。
如图28D所示，对上一步中结构进行刻蚀形成狭缝640，狭缝640止于SOI氧化硅B。
如图28E所示，对SOI底硅500(参见图28A)进行刻蚀形成空腔900。未被刻蚀的SOI底硅500(参见图28A)形成MEMS扬声器的支撑件。
如图28F所示，对SOI氧化硅B(参见图28A)进行刻蚀以释放振膜，形成MEMS扬声器晶圆。其中，每个振膜与对应的支撑件形成对应的一个MEMS扬声器。
以下结合附图，说明步骤二的实施过程：
如图28G的上部所示，提供可拉伸膜晶圆，可拉伸膜晶圆包括SOI底硅500(即辅助基底)、牺牲层C和PDMS层400(即可拉伸膜层)，其中，牺牲层C处于SOI底硅500和PDMS层400之间。
如图28G和图28H所示，将可拉伸膜晶圆与扬声器晶圆接合，以使得PDMS层400与扬声器晶圆中的扬声器膜层或者振膜层接合。
如图28I所示，释放牺牲层C(参见图28I)从而移除SOI底硅500(参见图28I)以露出PDMS层400。
以下结合附图，说明步骤三的实施过程：
如图28J所示，沿图中的切割线执行切割。
如图28K所示，通过切割得到多个带有可拉伸膜的扬声器。
图29G-图29I为根据本发明的另一个示例性实施例的示例性示出晶圆级制备MEMS扬声器的工艺流程的一系列截面示意图。该实施例中的工艺流程与上一实施例中的工艺流程大体类似，区别在于设置可拉伸膜的步骤，以及最终得到 的MEMS扬声器的结构。
在本实施例中，设置可拉伸膜的步骤包括：
如图29G所示，将PDMS溶液(即用于可拉伸膜的材料的溶液)涂覆在扬声器膜或者振膜所在的一侧，并且使得涂覆的溶液固化以形成PDMS层400(即可拉伸膜层)。
在设置可拉伸膜的步骤之后，类似地包括：
如图29H所示，沿图中的切割线执行切割。
如图29I所示，通过切割得到多个带有可拉伸膜的扬声器。
可以看出，图28K中的可拉伸膜是平直的，并且从上方覆盖振动用空间，图29I中的可拉伸膜包括凸起，并且该凸起填充在振动用空间内。
基于以上，本发明提出了如下技术方案：
1、一种MEMS扬声器，包括：
振膜，所述振膜的一端固定且另一端与另一部件之间设置有振动用空间；
可拉伸膜，分别与所述振膜和所述另一部件连接，且填充或者覆盖至少部分所述振动用空间。
2、根据1所述的扬声器，其中：
所述另一部件包括另一振膜，所述另一振膜的一端固定且另一端与所述振膜的另一端之间设置有所述振动用空间。
3、根据2所述的扬声器，其中：
所述可拉伸膜的两端分别固定至所述振膜和所述另一振膜的同侧表面，且所述可拉伸膜从所述振动用空间的一侧覆盖所述振动用空间。
4、根据3所述的扬声器，其中：
所述可拉伸膜的一端设置在所述振膜的一端，且所述可拉伸膜的另一端设置在所述另一振膜的一端。
5、根据3所述的扬声器，其中：
所述可拉伸膜的一端包括超出所述振膜的一端的延伸部分，且所述可拉伸膜的另一端包括超出所述另一振膜的一端的延伸部分。
6、根据3所述的扬声器，其中：
所述可拉伸膜的一端设置在所述振膜的一端和另一端之间；和/或
所述可拉伸膜的另一端设置在所述另一振膜的一端和另一端之间。
7、根据6所述的扬声器，其中：
所述可拉伸膜的一端和另一端到所述振动用空间的距离不同。
8、根据6所述的扬声器，其中：
所述可拉伸膜的一端和另一端到所述振动用空间的距离相同。
9、根据3所述的扬声器，其中：
所述可拉伸膜的朝向所述振动用空间的表面分别与所述振膜和所述另一振膜的同侧表面完全接触。
10、根据9所述的扬声器，其中：
所述可拉伸膜的与所述振动用空间相对的部分具有弯曲。
11、根据3所述的扬声器，其中：
所述可拉伸膜的朝向所述振动用空间的表面与所述振膜和所述另一振膜的同侧表面之间存在空隙。
12、根据11所述的扬声器，其中：
所述空隙位于所述振膜的一端与另一端之间；和/或
所述空隙位于所述另一振膜的一端与另一端之间。
13、根据11所述的扬声器，其中：
所述空隙位于所述振膜的另一端；和/或
所述空隙位于所述另一振膜的另一端。
14、根据13所述的扬声器，其中：
所述可拉伸膜是平直的，且所述振膜的另一端和/或所述另一振膜的另一端具有弯曲；或者
所述振膜和所述另一振膜是平直的，且所述可拉伸膜的与所述振动用空间相对的部分具有弯曲；或者
所述振膜的另一端和/或所述另一振膜的另一端具有弯曲，且所述可拉伸膜的与所述振动用空间相对的部分具有弯曲。
15、根据11所述的扬声器，其中：
所述空隙内设置有中间介质，所述中间介质分别与所述可拉伸膜和所述振膜接触，或者所述中间介质分别与所述可拉伸膜和所述另一振膜接触。
16、根据3所述的扬声器，其中：
所述可拉伸膜在振动方向上投影的面积小于所述振膜和所述另一振膜在振 动方向上投影的总面积。
17、根据3所述的扬声器，其中：
所述可拉伸膜与所述振膜相对的部分以及所述可拉伸膜与所述另一振膜相对的部分具有对称的图案。
18、根据3所述的扬声器，其中：
所述可拉伸膜与所述振膜相对的部分以及所述可拉伸膜与所述另一振膜相对的部分具有非对称的图案。
19、根据2所述的扬声器，其中：
所述可拉伸膜的两端分别固定至所述振膜和所述另一振膜的相对的端面。
20、根据2所述的扬声器，其中：
所述可拉伸膜的两端分别固定至所述振膜和所述另一振膜的同侧表面，所述可拉伸膜的与所述振动用空间相对的位置设置有凸起，所述凸起至少部分填充在所述振动用空间内。
21、根据1所述的扬声器，其中：
所述另一部件包括第二支撑件，所述振膜的一端固定在第一支撑件上，另一端与所述第二支撑件的上端之间设置有所述振动用空间。
22、根据20所述的扬声器，其中：
所述可拉伸膜的与所述振动用空间相对的部分是平直的；或者
所述可拉伸膜的与所述振动用空间相对的部分具有朝向所述振动用空间的弯曲。
23、根据1所述的扬声器，其中：
所述另一部件包括另一振膜，所述另一振膜的一端固定且另一端与所述振膜的另一端之间设置有所述振动用空间，所述振膜和所述另一振膜以局部连接的方式相互耦合。
24、根据1-23中任一项所述的扬声器，其中：
所述振动用空间包括狭缝、孔或槽。
25、根据1-23中任一项所述的扬声器，其中：
所述可拉伸振膜的厚度不超过500微米；且
所述可拉伸膜的杨氏模量不超过1000兆帕。
26、根据25所述的扬声器，其中：
所述可拉伸膜的厚度不超过100微米；且
所述可拉伸膜的杨氏模量不超过100兆帕。
27、根据26所述的扬声器，其中：
所述可拉伸膜的厚度不超过20微米；且
所述可拉伸膜的杨氏模量不超过10兆帕。
28、根据1-23中任一项所述的扬声器，其中：
当所述可拉伸膜的杨氏模量不超过1000兆帕时，所述可拉伸膜的厚度不超过所述振膜的厚度的50倍，进一步的，所述可拉伸膜的厚度不超过所述振膜的厚度的10倍；或者
可拉伸膜的材料包括硅橡胶或RTV橡胶或PDMS。
29、一种MEMS扬声器的制造方法，包括步骤：
形成MEMS扬声器晶圆，扬声器晶圆设置有多个MEMS扬声器，每个扬声器包括对应的支撑件；
在扬声器晶圆上为所述多个MEMS扬声器同时设置可拉伸膜；
执行切割，以形成多个带有可拉伸膜的MEMS扬声器。
30、根据29所述的方法，其中，设置可拉伸膜的步骤包括：
提供可拉伸膜晶圆，所述可拉伸膜晶圆包括可拉伸膜层、牺牲层和辅助基底，牺牲层处于可拉伸膜层与辅助基底之间；
将可拉伸膜晶圆与所述扬声器晶圆接合，以使得可拉伸膜层与扬声器晶圆的扬声器膜层接合；
释放所述牺牲层从而移除辅助基底以露出所述可拉伸膜层。
31、根据29所述的方法，其中，形成MEMS扬声器晶圆的步骤包括：
提供扬声器晶圆基础结构，所述基础结构提供基础结构自上而下依次包括SOI底硅、SOI氧化硅、SOI顶硅、第一电极层、压电层、第二电极层；
以MEMS方式刻蚀扬声器晶圆基础结构，以形成穿过SOI顶硅、第一电极层、压电层、第二电极层而止于SOI氧化硅的多个刻蚀部；
刻蚀SOI底硅，以形成与MEMS扬声器对应的多个空腔和多个支撑件，所述空间止于所述SOI氧化硅；
对SOI氧化硅进行刻蚀以贯穿所述多个刻蚀部以释放振膜，从而形成MEMS扬声器晶圆。
32、根据29所述的方法，其中，设置可拉伸膜的步骤包括：
将用于可拉伸膜的材料的溶液涂覆扬声器晶圆的扬声器膜层所在一侧；
使得涂覆的溶液固化以形成可拉伸膜层。
33、根据32所述的方法，其中：
形成MEMS扬声器晶圆的步骤包括：在扬声器晶圆的一侧基于MEMS工艺形成多个振动用空间；
“将用于可拉伸膜的材料的溶液涂覆扬声器晶圆的扬声器膜层所在一侧”的步骤中，溶液填充所述多个振动用空间；
“使得涂覆的溶液固化以形成可拉伸膜层”的步骤中，振动用空间内的溶液也固化。
34、一种电子设备，包括根据1-28中任一项所述的扬声器或者根据29-33中任一项所述的方法制造的扬声器。
尽管已经示出和描述了本发明的实施例，对于本领域的普通技术人员而言，可以理解在不脱离本发明的原理和精神的情况下可以对这些实施例进行变化，本发明的范围由所附权利要求及其等同物限定。

Claims (34)

  1. 一种MEMS扬声器，包括：
    振膜，所述振膜的一端固定且另一端与另一部件之间设置有振动用空间；
    可拉伸膜，分别与所述振膜和所述另一部件连接，且填充或者覆盖至少部分所述振动用空间。
  2. 根据权利要求1所述的扬声器，其中：
    所述另一部件包括另一振膜，所述另一振膜的一端固定且另一端与所述振膜的另一端之间设置有所述振动用空间。
  3. 根据权利要求2所述的扬声器，其中：
    所述可拉伸膜的两端分别固定至所述振膜和所述另一振膜的同侧表面，且所述可拉伸膜从所述振动用空间的一侧覆盖所述振动用空间。
  4. 根据权利要求3所述的扬声器，其中：
    所述可拉伸膜的一端设置在所述振膜的一端，且所述可拉伸膜的另一端设置在所述另一振膜的一端。
  5. 根据权利要求3所述的扬声器，其中：
    所述可拉伸膜的一端包括超出所述振膜的一端的延伸部分，且所述可拉伸膜的另一端包括超出所述另一振膜的一端的延伸部分。
  6. 根据权利要求3所述的扬声器，其中：
    所述可拉伸膜的一端设置在所述振膜的一端和另一端之间；和/或
    所述可拉伸膜的另一端设置在所述另一振膜的一端和另一端之间。
  7. 根据权利要求6所述的扬声器，其中：
    所述可拉伸膜的一端和另一端到所述振动用空间的距离不同。
  8. 根据权利要求6所述的扬声器，其中：
    所述可拉伸膜的一端和另一端到所述振动用空间的距离相同。
  9. 根据权利要求3所述的扬声器，其中：
    所述可拉伸膜的朝向所述振动用空间的表面分别与所述振膜和所述另一振膜的同侧表面完全接触。
  10. 根据权利要求9所述的扬声器，其中：
    所述可拉伸膜的与所述振动用空间相对的部分具有弯曲。
  11. 根据权利要求3所述的扬声器，其中：
    所述可拉伸膜的朝向所述振动用空间的表面与所述振膜和所述另一振膜的同侧表面之间存在空隙。
  12. 根据权利要求11所述的扬声器，其中：
    所述空隙位于所述振膜的一端与另一端之间；和/或
    所述空隙位于所述另一振膜的一端与另一端之间。
  13. 根据权利要求11所述的扬声器，其中：
    所述空隙位于所述振膜的另一端；和/或
    所述空隙位于所述另一振膜的另一端。
  14. 根据权利要求13所述的扬声器，其中：
    所述可拉伸膜是平直的，且所述振膜的另一端和/或所述另一振膜的另一端具有弯曲；或者
    所述振膜和所述另一振膜是平直的，且所述可拉伸膜的与所述振动用空间相对的部分具有弯曲；或者
    所述振膜的另一端和/或所述另一振膜的另一端具有弯曲，且所述可拉伸膜的与所述振动用空间相对的部分具有弯曲。
  15. 根据权利要求11所述的扬声器，其中：
    所述空隙内设置有中间介质，所述中间介质分别与所述可拉伸膜和所述振膜接触，或者所述中间介质分别与所述可拉伸膜和所述另一振膜接触。
  16. 根据权利要求3所述的扬声器，其中：
    所述可拉伸膜在振动方向上投影的面积小于所述振膜和所述另一振膜在振动方向上投影的总面积。
  17. 根据权利要求3所述的扬声器，其中：
    所述可拉伸膜与所述振膜相对的部分以及所述可拉伸膜与所述另一振膜相对的部分具有对称的图案。
  18. 根据权利要求3所述的扬声器，其中：
    所述可拉伸膜与所述振膜相对的部分以及所述可拉伸膜与所述另一振膜相对的部分具有非对称的图案。
  19. 根据权利要求2所述的扬声器，其中：
    所述可拉伸膜的两端分别固定至所述振膜和所述另一振膜的相对的端面。
  20. 根据权利要求2所述的扬声器，其中：
    所述可拉伸膜的两端分别固定至所述振膜和所述另一振膜的同侧表面，所述可拉伸膜的与所述振动用空间相对的位置设置有凸起，所述凸起至少部分填充在所述振动用空间内。
  21. 根据权利要求1所述的扬声器，其中：
    所述另一部件包括第二支撑件，所述振膜的一端固定在第一支撑件上，另一端与所述第二支撑件的上端之间设置有所述振动用空间。
  22. 根据权利要求20所述的扬声器，其中：
    所述可拉伸膜的与所述振动用空间相对的部分是平直的；或者
    所述可拉伸膜的与所述振动用空间相对的部分具有朝向所述振动用空间的弯曲。
  23. 根据权利要求1所述的扬声器，其中：
    所述另一部件包括另一振膜，所述另一振膜的一端固定且另一端与所述振膜的另一端之间设置有所述振动用空间，所述振膜和所述另一振膜以局部连接的方式相互耦合。
  24. 根据权利要求1-23中任一项所述的扬声器，其中：
    所述振动用空间包括狭缝、孔或槽。
  25. 根据权利要求1-23中任一项所述的扬声器，其中：
    所述可拉伸振膜的厚度不超过500微米；且
    所述可拉伸膜的杨氏模量不超过1000兆帕。
  26. 根据权利要求25所述的扬声器，其中：
    所述可拉伸膜的厚度不超过100微米；且
    所述可拉伸膜的杨氏模量不超过100兆帕。
  27. 根据权利要求26所述的扬声器，其中：
    所述可拉伸膜的厚度不超过20微米；且
    所述可拉伸膜的杨氏模量不超过10兆帕。
  28. 根据权利要求1-23中任一项所述的扬声器，其中：
    当所述可拉伸膜的杨氏模量不超过1000兆帕时，所述可拉伸膜的厚度不超过所述振膜的厚度的50倍，进一步的，所述可拉伸膜的厚度不超过所述振膜的厚度的10倍；或者
    可拉伸膜的材料包括硅橡胶或RTV橡胶或PDMS。
  29. 一种MEMS扬声器的制造方法，包括步骤：
    形成MEMS扬声器晶圆，扬声器晶圆设置有多个MEMS扬声器；
    在扬声器晶圆上为所述多个MEMS扬声器同时设置可拉伸膜；
    执行切割，以形成多个带有可拉伸膜的MEMS扬声器。
  30. 根据权利要求29所述的方法，其中，设置可拉伸膜的步骤包括：
    提供可拉伸膜晶圆，所述可拉伸膜晶圆包括可拉伸膜层、牺牲层和辅助基底，牺牲层处于可拉伸膜层与辅助基底之间；
    将可拉伸膜晶圆与所述扬声器晶圆接合，以使得可拉伸膜层与扬声器晶圆的扬声器膜层接合；
    释放所述牺牲层从而移除辅助基底以露出所述可拉伸膜层。
  31. 根据权利要求29所述的方法，其中，形成MEMS扬声器晶圆的步骤包括：
    提供扬声器晶圆基础结构，所述基础结构提供基础结构自上而下依次包括SOI底硅、SOI氧化硅、SOI顶硅、第一电极层、压电层、第二电极层；
    以MEMS方式刻蚀扬声器晶圆基础结构，以形成穿过SOI顶硅、第一电极层、压电层、第二电极层而止于SOI氧化硅的多个刻蚀部；
    刻蚀SOI底硅，以形成与MEMS扬声器对应的多个空腔和多个支撑件，所述空间止于所述SOI氧化硅；
    对SOI氧化硅进行刻蚀以贯穿所述多个刻蚀部以释放振膜，从而形成MEMS扬声器晶圆。
  32. 根据权利要求29所述的方法，其中，设置可拉伸膜的步骤包括：
    将用于可拉伸膜的材料的溶液涂覆扬声器晶圆的扬声器膜层所在一侧；
    使得涂覆的溶液固化以形成可拉伸膜层。
  33. 根据权利要求32所述的方法，其中：
    形成MEMS扬声器晶圆的步骤包括：在扬声器晶圆的一侧基于MEMS工艺形成多个振动用空间；
    “将用于可拉伸膜的材料的溶液涂覆扬声器晶圆的扬声器膜层所在一侧”的步骤中，溶液填充所述多个振动用空间；
    “使得涂覆的溶液固化以形成可拉伸膜层”的步骤中，振动用空间内的溶液也固化。
  34. 一种电子设备，包括根据权利要求1-28中任一项所述的扬声器或者根据权利要求29-33中任一项所述的方法制造的扬声器。
PCT/CN2023/115188 2022-09-09 2023-08-28 具有可拉伸膜的mems扬声器、其制造方法以及包括其的电子设备 WO2024051509A1 (zh)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101313628A (zh) * 2005-11-24 2008-11-26 株式会社村田制作所 电声变换器
US20150054095A1 (en) * 2013-08-26 2015-02-26 Samsung Electronics Co., Ltd. Capacitive micro-machined ultrasonic transducer and method of singulating the same
EP2938267A1 (en) * 2012-12-31 2015-11-04 Volcano Corporation Layout and method of singulating miniature ultrasonic transducers
CN114207854A (zh) * 2019-08-06 2022-03-18 日清纺微电子有限公司 压电元件

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101313628A (zh) * 2005-11-24 2008-11-26 株式会社村田制作所 电声变换器
EP2938267A1 (en) * 2012-12-31 2015-11-04 Volcano Corporation Layout and method of singulating miniature ultrasonic transducers
US20150054095A1 (en) * 2013-08-26 2015-02-26 Samsung Electronics Co., Ltd. Capacitive micro-machined ultrasonic transducer and method of singulating the same
CN114207854A (zh) * 2019-08-06 2022-03-18 日清纺微电子有限公司 压电元件

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