Membrane loudspeaker core, module and manufacturing method thereof, and electronic device

Abstract

This application relates to the field of acoustic-to-electric conversion technology, and more particularly to a MEMS loudspeaker core and its module, fabrication method, and electronic device. The MEMS loudspeaker core includes a support frame and a piezoelectric diaphragm. The edge of the piezoelectric diaphragm is connected to the support frame. The piezoelectric diaphragm includes a first electrode layer, a piezoelectric material layer, and a second electrode layer. The first and second electrode layers improve the overall vibration durability and flexibility of the piezoelectric diaphragm. In the three sequentially connected electrode segments of the second electrode layer, the difference between the feature size of the first electrode segment and the sum of the feature sizes of the second electrode segment and the feature size of the third electrode segment is less than or equal to a first preset value. Furthermore, the second electrode layer and the first hollow area of ​​the first electrode layer are positioned opposite each other, which is beneficial for improving the output sound pressure level. Therefore, under the same output sound pressure level requirement, it is beneficial to reduce the overall area of ​​the piezoelectric diaphragm and the overall volume.

Description

Technical Field

[0001] This application relates to the field of acoustic-to-electric conversion technology, and in particular to a MEMS loudspeaker core and its module, fabrication method, and electronic device. Background Technology

[0002] Speakers are used in many electronic devices such as mobile phones, tablets, PCs (Personal Computers), televisions, headphones, and audio equipment. Currently, the most commonly used type is the dynamic speaker, but dynamic speakers are relatively large and difficult to reduce in size.

[0003] With the development of semiconductor technology and MEMS (Micro Electro Mechanical Systems) technology, many manufacturers have launched MEMS loudspeakers. The basic principle of piezoelectric MEMS loudspeakers is to utilize the inverse piezoelectric effect of a piezoelectric thin film layer to convert electrical signals into mechanical vibrations, which drive air molecules to create sound pressure, thereby generating sound. Currently, MEMS loudspeakers are used in VR (Virtual Reality) glasses, automobiles, and other fields. However, the overall size of MEMS loudspeakers in these technologies needs further reduction. Summary of the Invention

[0004] This application provides a MEMS speaker core that helps reduce the overall size.

[0005] In a first aspect, this application provides a MEMS loudspeaker core, the MEMS loudspeaker core including a support frame and a piezoelectric diaphragm, the edge of the piezoelectric diaphragm being connected to the support frame, the piezoelectric diaphragm including a first electrode layer, a piezoelectric material layer and a second electrode layer, the first electrode layer being connected to the support frame, the first electrode layer having a first hollow area; the piezoelectric material layer being used for converting electrical energy into sound pressure, the piezoelectric material layer being disposed on the first electrode layer; the second electrode layer being disposed on the piezoelectric material layer, the second electrode layer including at least three sequentially connected electrode segments forming a second hollow area, the second electrode layer being disposed opposite to the first hollow area; in the three adjacent electrode segments, the difference between the sum of the feature dimensions of the first electrode segment and the feature dimensions of the second electrode segment and the feature dimension of the third electrode segment is less than or equal to a first preset value.

[0006] By configuring the MEMS speaker core to include a support frame and a piezoelectric diaphragm, with the edge of the piezoelectric diaphragm connected to the support frame, the piezoelectric diaphragm includes a first electrode layer, a piezoelectric material layer, and a second electrode layer. The first electrode layer is connected to the support frame and has a first hollow area. The piezoelectric material layer is used for converting electrical energy into sound pressure and is disposed on the first electrode layer. The second electrode layer is disposed on the piezoelectric material layer and includes at least three sequentially connected electrode segments forming a second hollow area. The second electrode layer is disposed opposite to the first hollow area. In the three adjacent electrode segments, the difference between the feature size of the first electrode segment and the sum of the feature sizes of the second electrode segment and the feature size of the third electrode segment is less than or equal to a first preset value. The first electrode layer with the first hollow area, the first electrode layer forming the second hollow area, and the second electrode layer with the first hollow area are all connected in a specific manner. The two electrode layers can conduct electrical signals to the piezoelectric material layer to generate sound pressure and sound, and can also provide elasticity to the piezoelectric material layer to improve the overall vibration durability of the piezoelectric diaphragm. Furthermore, they can improve the overall vibration flexibility of the piezoelectric diaphragm through the first and second hollow areas. In addition, in the three sequentially connected electrode segments of the second electrode layer, the difference between the feature size of the first electrode segment and the sum of the feature sizes of the second electrode segment and the feature size of the third electrode segment is less than or equal to a first preset value. Moreover, the second electrode layer and the first hollow area of ​​the first electrode layer are arranged opposite to each other, which is beneficial to improving the output sound pressure level. Thus, under the same output sound pressure level requirement, it is beneficial to reduce the overall area of ​​the piezoelectric diaphragm and reduce the overall volume of the MEMS speaker core and the corresponding MEMS speaker module.

[0007] In one possible implementation, the second electrode layer extends spirally along the surface plane of the piezoelectric material layer to form the second hollow region. The second electrode layer includes at least three electrode segments connected sequentially in a spiral outward direction. In the three adjacent electrode segments connected sequentially in a spiral outward direction, the characteristic dimensions of the first electrode segment, the second electrode segment, and the third electrode segment respectively include the radius of curvature of the first electrode segment, the radius of curvature of the second electrode segment, and the radius of curvature of the third electrode segment.

[0008] In another possible implementation, the second electrode layer includes an inner boundary and an outer boundary relative to the helical center; the inner boundary includes at least three inner segments connected sequentially in a helical outward direction; in the three adjacent inner segments connected sequentially in a helical outward direction, the characteristic dimensions of the first, second, and third electrode segments respectively include the radius of curvature of the first, second, and third inner segments.

[0009] In another possible implementation, the outer boundary includes at least three outer segments connected sequentially in a spiral outward direction; in the three adjacent outer segments connected sequentially in a spiral outward direction, the characteristic dimensions of the first, second, and third electrode segments respectively include the radius of curvature of the first, second, and third outer segments.

[0010] In another possible implementation, the first inner segment, the second inner segment, and the third inner segment are respectively configured to correspond to the first outer segment, the second outer segment, and the third outer segment, and the radius of curvature of the first inner segment, the second inner segment, and the third inner segment is smaller than the radius of curvature of the first outer segment, the second outer segment, and the third outer segment, respectively.

[0011] In another possible implementation, the second electrode layer is provided with a through structure that penetrates the second electrode layer and the piezoelectric material layer, and the through structure is connected to the first hollow area.

[0012] In another possible implementation, the through-structure includes a helical slit that extends helically along the surface plane of the piezoelectric material layer.

[0013] In another possible implementation, the spiral slot includes at least three slot segments connected sequentially in a spiral outward direction; in the three adjacent slot segments connected sequentially in a spiral outward direction, the difference between the sum of the curvature radii of the first slot segment and the second slot segment and the curvature radii of the third slot segment is less than or equal to a second preset value.

[0014] In another possible implementation, the first preset value is less than or equal to 10% of the characteristic dimension of the third electrode segment; and / or, the second preset value is less than or equal to 10% of the radius of curvature of the third slit segment; and / or, the thickness of the second electrode layer is greater than or equal to 100 nanometers and less than or equal to 500 nanometers; and / or, the thickness of the piezoelectric material layer is greater than or equal to 10 micrometers and less than or equal to 20 micrometers; and / or, the thickness of the first electrode layer is greater than or equal to 100 nanometers and less than or equal to 500 nanometers; and / or, the width of the spiral slit is less than or equal to 5 micrometers.

[0015] In another possible implementation, the piezoelectric material layer is further provided with a second electrode terminal facing the surface of the second electrode layer, and the second electrode terminal is connected to the second electrode layer;

[0016] The through structure separates the outer spiral end of the second electrode layer and connects the inner spiral end of the second electrode layer. The second electrode terminal is connected to one of the outer portion of the outer end of the second electrode layer and the inner portion of the outer end of the second electrode layer.

[0017] In another possible implementation, the first hollow region extends spirally along another surface plane of the piezoelectric material layer, and the inner and outer boundaries of the first hollow region are respectively positioned opposite to the inner and outer boundaries of the second electrode layer.

[0018] In another possible implementation, the piezoelectric material layer is provided with a spiral groove facing the surface of the first electrode layer, and the inner and outer boundaries of the spiral groove are respectively positioned opposite to the inner and outer boundaries of the first hollow area.

[0019] In another possible implementation, in the same radius of curvature direction of the first electrode layer, the radius difference between the inner boundary of the first hollow region and the inner boundary of the spiral groove is less than or equal to 10% of the radius of curvature of the inner boundary of the spiral groove; and / or, in the same radius of curvature direction of the first electrode layer, the radius difference between the outer boundary of the first hollow region and the outer boundary of the spiral groove is less than or equal to 10% of the radius of curvature of the outer boundary of the spiral groove; and / or, the thickness of the portion of the piezoelectric material layer disposed opposite to the spiral groove is greater than or equal to 5 micrometers and less than or equal to 10 micrometers; and / or, in the same radius of curvature direction of the second electrode layer, the radius difference between the inner boundary of the first hollow region and the inner boundary of the second electrode layer is less than or equal to 10% of the radius of curvature of the inner boundary of the second electrode layer; and / or, in the same radius of curvature direction of the second electrode layer, the radius difference between the outer boundary of the first hollow region and the outer boundary of the second electrode layer is less than or equal to 10% of the radius of curvature of the outer boundary of the second electrode layer.

[0020] In another possible implementation, the piezoelectric material layer is provided with a connecting through hole, and the piezoelectric diaphragm further includes a first electrode terminal, which is at least partially disposed on the hole wall of the connecting through hole; one end of the first electrode terminal is connected to the first electrode layer, and the other end of the first electrode terminal is spaced apart from the second electrode layer.

[0021] In another possible implementation, the cross-section of the connecting through hole is set to a rectangle or a rounded rectangle; the length of the cross-section of the connecting through hole is greater than or equal to 50 micrometers and less than or equal to 100 micrometers, and / or the width of the cross-section of the connecting through hole is greater than or equal to 50 micrometers and less than or equal to 100 micrometers; and / or, the first electrode terminal includes a cylindrical segment, which is at least partially embedded in the connecting through hole.

[0022] In another possible implementation, the piezoelectric diaphragm includes two symmetrically arranged diaphragm segments, each segment comprising a first electrode layer, the piezoelectric material layer, and a second electrode layer.

[0023] In another possible implementation, in the two membrane segments, the spiral outer ends of the two second electrode layers are connected and the spiral outer ends of the second hollowed-out regions are connected, and the spiral inner portions of the two second electrode layers are arranged opposite to each other.

[0024] In another possible implementation, the inner spiral portions of the two second electrode layers are connected, or the inner spiral portions of the two second electrode layers are spaced apart.

[0025] In another possible implementation, the piezoelectric diaphragm comprises two symmetrically arranged segments, each segment comprising two symmetrically arranged diaphragm segments; in the two symmetrically arranged segments, the outer spiral ends of the second electrode layer face each other, and the inner spiral ends of the second electrode layer face away from each other.

[0026] In another possible implementation, at least three sequentially connected electrode segments are respectively configured as circular or elliptical and form the second hollow area. The feature dimensions of the first electrode segment, the second electrode segment, and the third electrode segment respectively include the radius of curvature of the first electrode segment, the radius of curvature of the second electrode segment, and the radius of curvature of the third electrode segment.

[0027] In another possible implementation, the piezoelectric diaphragm includes at least two segments, each segment comprising a first electrode layer, the piezoelectric material layer, and a second electrode layer, the segments being circumferentially distributed around the thickness direction of the piezoelectric material layer.

[0028] In another possible implementation, at least a portion of the electrode segments have increased feature size along a direction toward the circumferential distribution center of the membrane segments; and / or, the second electrode layer further includes connecting strips that extend along the outer envelope of the electrode segments of two adjacent membrane segments.

[0029] In another possible implementation, the second electrode layer includes at least three connected triangular frames, with the same edge of the third triangular frame connecting the edges of the first and second triangular frames to form the second cutout area; the first electrode segment, the second electrode segment, and the third electrode segment are respectively configured as the edges of the three connected triangular frames, and the feature dimensions of the first electrode segment, the second electrode segment, and the third electrode segment respectively include the edge length of the first electrode segment, the edge length of the second electrode segment, and the edge length of the third electrode segment.

[0030] In another possible implementation, the piezoelectric diaphragm comprises two segments, each segment including a first electrode layer, a piezoelectric material layer, and a second electrode layer, the segments being centrally symmetrical about the thickness direction of the piezoelectric material layer; in the two segments, the sides of the largest triangular frame are connected.

[0031] Secondly, this application provides a MEMS speaker module, the MEMS speaker module including a module circuit board, a module housing and the aforementioned MEMS speaker core, one end of the support frame facing away from the piezoelectric diaphragm is connected to the module circuit board, the second electrode layer and the first electrode layer are respectively electrically connected to the module circuit board; the module housing is provided with a housing sound outlet, and the MEMS speaker core is at least partially disposed within the module housing.

[0032] Thirdly, this application provides an electronic device, which includes a device housing and the aforementioned MEMS speaker module. The device housing is provided with a device sound outlet, and the MEMS speaker module is disposed within the device housing.

[0033] Fourthly, this application provides a method for fabricating a MEMS loudspeaker core, the method comprising the following steps:

[0034] A first electrode intermediate layer is formed on the support block;

[0035] A piezoelectric material layer is formed on the intermediate layer of the first electrode;

[0036] A second electrode intermediate layer is formed on the piezoelectric material layer;

[0037] The second electrode intermediate layer is processed into a second electrode layer with a second hollow area. The second electrode layer includes at least three electrode segments connected in sequence. In the three adjacent electrode segments, the difference between the sum of the feature dimensions of the first electrode segment and the feature dimensions of the second electrode segment and the feature dimension of the third electrode segment is less than or equal to a first preset value.

[0038] The first electrode intermediate layer is processed into a first electrode layer with a first hollow area, and the first hollow area is disposed opposite to the second electrode layer.

[0039] In one possible implementation, after the step of forming a second electrode intermediate layer on the piezoelectric material layer, the method for fabricating the MEMS speaker core further includes the following steps:

[0040] A through-structure is formed on the intermediate layer of the second electrode or the second electrode layer, the through-structure penetrating the second electrode layer and the piezoelectric material layer.

[0041] In another possible implementation, the step of processing the second electrode intermediate layer into a second electrode layer having a second hollow region includes:

[0042] The second electrode terminal is fabricated in the intermediate layer of the second electrode, and the second electrode terminal is connected to the second electrode layer.

[0043] In another possible implementation, the step of processing the first electrode intermediate layer into a first electrode layer having a first hollow region includes:

[0044] The support block, the first electrode intermediate layer, and the piezoelectric material layer are processed to form a support frame, and the piezoelectric material layer forms a spiral groove facing the surface of the first electrode layer. The inner and outer boundaries of the spiral groove are respectively set opposite to the inner and outer boundaries of the first hollow area.

[0045] In another possible implementation, after the step of forming a piezoelectric material layer on the first electrode intermediate layer, the method for fabricating the MEMS speaker core further includes the step of forming a connection via on the piezoelectric material layer, the connection via extending to the first electrode intermediate layer;

[0046] The step of forming a second electrode intermediate layer on the piezoelectric material layer includes:

[0047] At least a portion of a first electrode terminal is formed on the wall of the connecting through hole, and one end of the first electrode terminal is connected to the first electrode intermediate layer.

[0048] In another possible implementation, the step of processing the second electrode intermediate layer into a second electrode layer having a second hollow region includes:

[0049] The other end of the first electrode terminal is spaced apart from the second electrode layer. Attached Figure Description

[0050] Figure 1A schematic diagram of the structure of an embodiment of the electronic device provided in this application;

[0051] Figure 2 This is a schematic diagram of the structure of an embodiment of the MEMS speaker module provided in this application;

[0052] Figure 3 An exploded view of an embodiment of the MEMS speaker module provided in this application;

[0053] Figure 4 A top view of a piezoelectric diaphragm in one embodiment of the MEMS speaker module provided in this application;

[0054] Figure 5 This is a schematic diagram of the piezoelectric diaphragm in one embodiment of the MEMS speaker module provided in this application, viewed from below.

[0055] Figure 6 A partial structural schematic diagram of an embodiment of the MEMS speaker module provided in this application;

[0056] Figure 7 Another partial structural schematic diagram of an embodiment of the MEMS speaker module provided in this application;

[0057] Figure 8 for Figure 7 A cross-sectional view at position AA in the middle;

[0058] Figure 9 for Figure 7 A three-dimensional sectional view at position AA;

[0059] Figure 10 for Figure 7 A three-dimensional sectional view of the BB position;

[0060] Figure 11 This is a schematic diagram of another embodiment of the MEMS speaker module provided in this application;

[0061] Figure 12 A top view of the piezoelectric diaphragm in another embodiment of the MEMS speaker module provided in this application;

[0062] Figure 13 A top view of the piezoelectric diaphragm in another embodiment of the MEMS speaker module provided in this application;

[0063] Figure 14 A top view of the piezoelectric diaphragm in another embodiment of the MEMS speaker module provided in this application;

[0064] Figure 15 A top view of the piezoelectric diaphragm in another embodiment of the MEMS speaker module provided in this application;

[0065] Figure 16 A schematic diagram of the fabrication process of an embodiment of the MEMS loudspeaker core provided in this application;

[0066] Figure 17 A schematic flowchart of an embodiment of the method for fabricating a MEMS loudspeaker core provided in this application;

[0067] Figure 18 This is a schematic flowchart of another embodiment of the method for fabricating the MEMS speaker core provided in this application. Detailed Implementation

[0068] The terms "first," "second," and "third," etc., used in this application specification, claims, and drawings are used to distinguish different objects, not to limit a specific order.

[0069] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0070] Speakers are used in many electronic devices such as mobile phones, tablets, PCs (Personal Computers), televisions, headphones, and audio equipment. Currently, the most commonly used type is the dynamic speaker, but dynamic speakers are relatively large and difficult to reduce in size.

[0071] With the development of semiconductor technology and MEMS (Micro Electro Mechanical Systems) technology, many manufacturers have launched MEMS loudspeakers. The basic principle of piezoelectric MEMS loudspeakers is to utilize the inverse piezoelectric effect of a piezoelectric thin film layer to convert electrical signals into mechanical vibrations, which drive air molecules to create sound pressure, thereby generating sound. Currently, MEMS loudspeakers are used in VR (Virtual Reality) glasses, automobiles, and other fields. However, the overall size of MEMS loudspeakers in these technologies needs further reduction.

[0072] Therefore, this application provides a method for fabricating a MEMS speaker core, a MEMS speaker module, an electronic device, and a MEMS speaker core, which helps to reduce the overall size.

[0073] The electronic devices provided in this application may include, but are not limited to, mobile phones, tablets, laptops, PCs (Personal Computers), Ultra-mobile Personal Computers (UMPCs), handheld computers, walkie-talkies, netbooks, POS machines, Personal Digital Assistants (PDAs), wearable devices, security equipment, televisions, and speakers, etc., which are mobile or fixed terminals. Mobile phones may include candybar phones and foldable phones, etc., and wearable devices may include VR glasses, smart glasses, headphones, smartwatches, and smart bracelets, etc. This application primarily uses mobile phones as an example for illustration. Without obvious conflict, the following structure can also be applied to other electronic devices besides mobile phones.

[0074] Figure 1 A schematic diagram of the structure of an electronic device 100 in one embodiment of this application is shown. The electronic device 100 includes a device housing 10 and a MEMS speaker module 20. The device housing 10 is provided with a device sound outlet 11, and the MEMS speaker module 20 is disposed inside the device housing 10.

[0075] The device housing 10 may include a mid-frame and a back cover; when the electronic device has a display function, it may also include a screen. The aforementioned mid-frame, along with the device circuit board, battery, camera module, USB device, etc., may be disposed between the screen and the back cover. The mid-frame serves as a mounting frame for the electronic device, and the aforementioned components such as the device circuit board, battery, camera module, USB device, and MEMS speaker module 20 may be mounted on the mid-frame. The device's sound outlet 11 may also be mounted on the mid-frame.

[0076] Furthermore, in the electronic device 100 provided in this application embodiment, the device circuit board may include a main device circuit board and a secondary device circuit board. The main device circuit board may be used to integrate a control chip, which may be configured as an application processor (AP), etc. In some embodiments, the main device circuit board may be electrically connected to a screen, and the main device circuit board may be used to control the display screen to display images or videos. The secondary device circuit board may be used to integrate electronic components such as antennas (e.g., 5G antennas) and radio frequency front-ends. The secondary device circuit board may also be electrically connected to the main device circuit board through a connection structure to realize data and signal transmission between the secondary device circuit board and the main device circuit board. The connection structure may be a flexible printed circuit (FPC), a wire, or an enameled wire, etc.

[0077] The aforementioned MEMS speaker module 20 can be electrically connected to the device sub-circuit board to receive electrical signals used to generate sound pressure and sound. At this time, the audio signal type electrical signal sent by the device main circuit board is transmitted to the MEMS speaker module 20 via the device sub-circuit board, and is converted into sound wave output by the MEMS speaker module 20, which can be output through the device sound outlet 11 on the device housing 10.

[0078] Among them, reference Figure 2 and Figure 3 In one embodiment provided in this application, the MEMS speaker module 20 includes a module circuit board 210, a module housing 220, and a MEMS speaker core. The module circuit board 210 can be configured as a PCB (Printed Circuit Board) circuit board, an FPC (Flexible Printed Circuit Board) circuit board, etc. The module housing 220 is provided with a housing sound outlet 221. The MEMS speaker core is at least partially disposed within the module housing 220. The housing sound outlet 221 can be configured to be opposite to the aforementioned device sound outlet 11 to facilitate smooth sound wave output.

[0079] The MEMS speaker core includes a support frame 230 and a piezoelectric diaphragm. The support frame 230 can be made of materials such as Si (silicon). The support frame 230 can be set as a circular frame or a square frame; or, the support frame 230 can be set as a cylindrical shape, and the cross-section of the support frame 230 can be set as a circular, elliptical, racetrack-shaped, rounded rectangle or rectangle shape, etc.

[0080] The edge of the piezoelectric diaphragm is connected to the support frame 230, specifically through methods such as sputtering. Figure 3 The piezoelectric diaphragm can be configured to include a first electrode layer 240, a piezoelectric material layer 250, and a second electrode layer 260. The piezoelectric material layer 250 is disposed on the first electrode layer 240, and the second electrode layer 260 is disposed on the piezoelectric material layer 250. This can be understood as the second electrode layer 260, the piezoelectric material layer 250, and the first electrode layer 240 being stacked sequentially. The first electrode layer 240 and the second electrode layer 260 can be made of conductive materials such as Au (gold), Pt (platinum), and Cr (chromium), and can be specifically fabricated using sputtering. The piezoelectric material layer 250 is used for the conversion of electrical energy into sound pressure. The piezoelectric material layer 250 can be specifically made of piezoelectric materials such as PZT ceramic, AlN ceramic (alumina ceramic), and BaTiO3 ceramic (barium titanate ceramic); the piezoelectric material layer 250 can also be fabricated using sputtering.

[0081] At this time, the first electrode layer 240 can be connected to the support frame 230 to achieve the connection between the edge of the piezoelectric diaphragm and the support frame 230. Specifically, the first electrode layer 240 can be connected to the support frame 230 by sputtering molding or other methods.

[0082] The second electrode layer 260 and the first electrode layer 240 are electrically connected to the module circuit board 210, for example, through wire bonding, thereby achieving electrical connection between the positive and negative electrodes of the piezoelectric diaphragm and enabling the input of electrical signals used to generate sound pressure and sound. Referring to the above, this electrical signal can be sent from the main circuit board of the device, pass through the secondary circuit board, and then reach the module circuit board 210.

[0083] In addition, the end of the support frame 230 facing away from the piezoelectric diaphragm is connected to the module circuit board 210, for example... Figure 3 The lower end of the middle support frame 230 can be connected to the module circuit board 210 by means of adhesive bonding, so as to achieve relative fixation between the support frame 230 and the module circuit board 210.

[0084] in, Figure 4 , Figure 5 The paper presents a top view and a bottom view of the piezoelectric diaphragm in one embodiment of the MEMS speaker module provided in this application; see reference. Figure 5 The first electrode layer 240 has a first hollow area 241, which can be understood as a structure that penetrates the first electrode layer 240, such as a through hole or a notch; wherein, the first hollow area 241 can be formed by etching or other methods.

[0085] Reference Figure 4 The second electrode layer 260 includes at least three sequentially connected electrode segments 261 forming a second hollow region 262. The second hollow region 262 can be understood as a structure penetrating the second electrode layer 260, such as a through hole or a notch. The three sequentially connected electrode segments 261 can be referred to... Figure 4Electrode segments 261a, 261b, and 261c are separated by dashed lines. The second electrode layer 260 is positioned opposite the first hollowed-out region 241 of the first electrode layer 240. This can be understood as a projection along the piezoelectric material layer 250, where the projection of the second electrode layer 260 at least partially overlaps with the projection of the first hollowed-out region 241, including the coincidence of their projection boundaries. Among the three adjacent electrode segments 261, for example, for electrode segments 261a, 261b, and 261c, the difference between the sum of the characteristic dimensions of the first electrode segment 261 (electrode segment 261a) and the second electrode segment 261 (electrode segment 261b) and the characteristic dimension of the third electrode segment 261 (electrode segment 261c) is less than or equal to a first preset value. This can be understood as the sum of the characteristic dimensions of the first electrode segment 261 (electrode segment 261a) and the second electrode segment 261 (electrode segment 261b) being approximately equal to the characteristic dimension of the third electrode segment 261 (electrode segment 261c). "Approximately equal" can be understood as having a small difference, for example, the first preset value is less than or equal to 10% of the characteristic dimension of the third electrode segment 261 (electrode segment 261c). The first preset value can be further set to be less than or equal to 5% of the characteristic dimension of the third electrode segment 261 (electrode segment 261c).

[0086] The characteristic dimension can be understood as the dimension that distinguishes different electrode segments 261. For example, the characteristic dimension can be the radius of curvature corresponding to an arc segment, the radius corresponding to a circle, the side length corresponding to a triangle, the length or width corresponding to a rectangle, etc.

[0087] In some implementations, refer to Figure 4 The second electrode layer 260 can be configured to extend spirally along the surface plane of the piezoelectric material layer 250 to form a second hollow region 262. The second electrode layer 260 includes at least three electrode segments 261 connected sequentially in a spiral outward direction. Among the three adjacent electrode segments 261 connected sequentially in a spiral outward direction, for example, for the aforementioned electrode segments 261a, 261b, and 261c, the characteristic dimensions of the first electrode segment 261 (electrode segment 261a), the second electrode segment 261 (electrode segment 261b), and the third electrode segment 261 (electrode segment 261c) respectively include the radius of curvature of the first electrode segment 261 (electrode segment 261a), the radius of curvature of the second electrode segment 261 (electrode segment 261b), and the radius of curvature of the third electrode segment 261 (electrode segment 261c). At this time, the difference between the sum of the curvature radius of the first electrode segment 261 (electrode segment 261a) and the curvature radius of the second electrode segment 261 (electrode segment 261b) and the curvature radius of the third electrode segment 261 (electrode segment 261a) is less than or equal to the first preset value mentioned above.

[0088] In some embodiments, the characteristic dimensions of the first electrode segment 261 (electrode segment 261a), the second electrode segment 261 (electrode segment 261b), and the third electrode segment 261 (electrode segment 261c) arranged sequentially can form a Fibonacci sequence, and the second electrode layer 260 can be correspondingly extended along the Fibonacci line or the envelope of the Fibonacci line.

[0089] Of course, electrode segment 261 and its feature dimensions can also be set in other forms, for example, as described below for... Figure 13 , Figure 14 , Figure 15 or Figure 16 The detailed description may take any form, or other forms, but this implementation method is not limited in this regard.

[0090] In this embodiment, the first electrode layer 240 with a first hollowed-out region 241 and the second electrode layer 260 with a second hollowed-out region 262 can both conduct electrical signals to the piezoelectric material layer 250 to generate sound pressure and sound through the piezoelectric material layer 250, and provide elasticity to the piezoelectric material layer 250 to improve the overall vibration durability of the piezoelectric diaphragm, and improve the overall vibration flexibility of the piezoelectric diaphragm through the first hollowed-out region 241 and the second hollowed-out region 262, respectively. In addition, in the three sequentially connected electrode segments 261 of the second electrode layer 260, the difference between the feature size of the first electrode segment 261 and the sum of the feature sizes of the second electrode segment 261 and the feature size of the third electrode segment 261 is less than or equal to a first preset value, and the second electrode layer 260 is arranged opposite to the first hollowed-out region 241 of the first electrode layer 240, which is beneficial to improving the output sound pressure level. Thus, under the same output sound pressure level requirement, it is beneficial to reduce the overall area of ​​the piezoelectric diaphragm and reduce the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0091] In some implementations, refer to Figure 4 The second electrode layer 260 includes an inner boundary and an outer boundary relative to the helical center; the inner boundary includes at least three inner side segments 263 connected sequentially in a direction outward along the helix, for example... Figure 4The inner segments 263a, 263b, and 263c are separated by dashed lines. Among the three adjacent inner segments 263 connected sequentially in a spiral outward direction, the characteristic dimensions of the first electrode segment 261 (electrode segment 261a), the second electrode segment 261 (electrode segment 261b), and the third electrode segment 261 (electrode segment 261c) respectively include the radius of curvature of the first inner segment 263 (inner segment 263a), the second inner segment 263 (inner segment 263b), and the third inner segment 263 (inner segment 263c). This can be understood as using the radius of curvature of the inner boundary of the second electrode layer 260 as the characteristic dimension, which is beneficial to improving the vibration stability of the piezoelectric diaphragm at the inner boundary, improving the output sound pressure level, reducing the overall area of ​​the piezoelectric diaphragm, and reducing the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20. In some embodiments, the inner boundary of the second electrode layer 260 may be provided as a Fibonacci line or the envelope of a Fibonacci line.

[0092] In some embodiments, the outer boundary includes at least three outer segments 264 connected sequentially in a spiral outward direction, for example... Figure 4 The outer segments 264a, 264b, and 264c are separated by dashed lines. Among the three adjacent outer segments 264 connected sequentially in a spiral outward direction, the characteristic dimensions of the first electrode segment 261 (electrode segment 261a), the second electrode segment 261 (electrode segment 261b), and the third electrode segment 261 (electrode segment 261c) respectively include the radius of curvature of the first outer segment 264 (electrode segment 264a), the second outer segment 264 (electrode segment 264b), and the third outer segment 264 (electrode segment 264c). This can be understood as using the radius of curvature of the outer boundary of the second electrode layer 260 as the characteristic dimension, which is beneficial to improving the vibration stability of the piezoelectric diaphragm at the outer boundary, improving the output sound pressure level, reducing the overall area of ​​the piezoelectric diaphragm, and reducing the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20. In some embodiments, the outer boundary of the second electrode layer 260 may be provided as a Fibonacci line or the envelope of a Fibonacci line.

[0093] In some implementations, refer to Figure 4The first inner segment 263 (inner segment 263a), the second inner segment 263 (inner segment 263b), and the third inner segment 263 (inner segment 263c) are respectively set to correspond to the first outer segment 264 (outer segment 264a), the second outer segment 264 (outer segment 264b), and the third outer segment 264 (outer segment 264c). The radius of curvature of the first inner segment 263 (inner segment 263a), the radius of curvature of the second inner segment 263 (inner segment 263b), and the radius of curvature of the third inner segment 263 (inner segment 263c) are respectively set to correspond to the first outer segment 264 (outer segment 264a), the second outer segment 264 (outer segment 264b), and the third inner segment 264 (outer segment 264c). The radius of curvature of the inner segment 263c is smaller than that of the first outer segment 264 (outer segment 264a), the second outer segment 264 (outer segment 264b), and the third outer segment 264 (outer segment 264c), respectively. This is beneficial to further improve the vibration stability of the piezoelectric diaphragm at the inner and outer boundaries, improve the output sound pressure level, reduce the overall area of ​​the piezoelectric diaphragm, and reduce the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0094] In some implementations, refer to Figure 4 , Figure 5 and Figure 6 The second electrode layer 260 has a through structure 265 that penetrates the second electrode layer 260 and the piezoelectric material layer 250, and is connected to the first hollow area 241. The through structure 265 can be configured as a gap, notch, etc., and can be formed by etching or other methods.

[0095] In this embodiment, the through structure 265 is beneficial for increasing the vibration amplitude of the piezoelectric diaphragm, for increasing the output sound pressure level, for reducing the overall area of ​​the piezoelectric diaphragm, and for reducing the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0096] Among them, reference Figure 4 , Figure 5 and Figure 6 The through structure 265 may include a spiral slit that extends spirally along the surface plane of the piezoelectric material layer 250, thereby helping to further enhance the vibration amplitude of the piezoelectric diaphragm.

[0097] In some implementations, refer to Figure 4 The spiral seam includes at least three slot segments 266 connected sequentially in a spiral outward direction, for example... Figure 4The slit segments 266a, 266b, and 266c are separated by dashed lines. In three adjacent slit segments 266 connected sequentially in a spiral outward direction, such as the aforementioned slit segments 266a, 266b, and 266c, the difference between the sum of the curvature radii of the first slit segment 266 (slit segment 266a) and the second slit segment 266 (slit segment 266b) and the curvature radius of the third slit segment 266 (slit segment 266c) is less than or equal to a second preset value, thereby helping to further improve the vibration amplitude of the piezoelectric diaphragm. This can be understood as the sum of the radii of curvature of the first slit segment 266 (slit segment 266a) and the second slit segment 266 (slit segment 266b) being approximately equal to the radii of curvature of the third slit segment 266 (slit segment 266c). "Approximately equal" can be understood as a small difference, for example, a second preset value less than or equal to 10% of the radii of curvature of the third slit segment 266 (slit segment 266c). The second preset value can be further set to be less than or equal to 5% of the radii of curvature of the third slit segment 266 (slit segment 266c). In some embodiments, the spiral slit can be extended along a Fibonacci line or the envelope of a Fibonacci line.

[0098] Reference Figure 7 , Figure 8 and Figure 9 In some embodiments, the width of the spiral slit is less than or equal to 5 micrometers, which is beneficial to further improve the vibration amplitude of the piezoelectric diaphragm.

[0099] Reference Figure 7 , Figure 8 and Figure 9 In some embodiments, the thickness of the second electrode layer 260 is greater than or equal to 100 nanometers and less than or equal to 500 nanometers, the thickness of the piezoelectric material layer 250 is greater than or equal to 10 micrometers and less than or equal to 20 micrometers, and the thickness of the first electrode layer 240 is greater than or equal to 100 nanometers and less than or equal to 500 nanometers, respectively, which is beneficial to improving the output sound pressure level. Thus, under the same output sound pressure level requirement, it is beneficial to reduce the overall area of ​​the piezoelectric diaphragm, and to reduce the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0100] Reference Figure 7In some embodiments, the surface of the piezoelectric material layer 250 facing the second electrode layer 260 is further provided with a second electrode terminal 267, which is connected to the second electrode layer 260 to facilitate the connection of electrical signals to the second electrode layer 260. For example, the second electrode layer 260 can be connected to electrical signals through the aforementioned main circuit board, secondary circuit board, module circuit board 210, and corresponding wires. The second electrode terminal 267 can be obtained together with the second electrode layer 260 by sputtering.

[0101] Reference Figure 7 In some embodiments, the through structure 265 separates the outer spiral end of the second electrode layer 260 and connects the inner spiral end of the second electrode layer 260, so that the two parts of the second electrode layer 260 located on both sides of the through structure 265 can be electrically connected through the inner spiral end, thereby reducing the number of electrode terminals and reducing the interference of the electrode terminals on vibration, which is beneficial to further improve the vibration stability of the piezoelectric diaphragm.

[0102] The second electrode terminal 267 is connected to either the outermost portion or the innermost portion of the outer end of the second electrode layer 260. For example, the second electrode terminal 267 is connected to either the outermost or innermost portion of the outer end of the second electrode layer 260, thereby reducing the number of electrode terminals and minimizing interference from the electrode terminals on vibration, which is beneficial for further improving the vibration stability of the piezoelectric diaphragm. The outermost portion of the outer end of the second electrode layer 260 has a relatively small vibration amplitude. When the second electrode terminal 267 is connected to the outermost portion of the outer end of the second electrode layer 260, it helps reduce the risk of disconnection between the second electrode terminal 267 and the second electrode layer 260, which is beneficial for improving the service life of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0103] Reference Figure 5 , Figure 8 In some embodiments, the first hollow region 241 of the first electrode layer 240 extends spirally along another surface plane of the piezoelectric material layer 250, and the inner and outer boundaries of the first hollow region 241 are respectively positioned opposite to the inner and outer boundaries of the second electrode layer 260. This can be understood as follows: when projected along the thickness direction of the piezoelectric material layer 250, the inner and outer boundaries of the first hollow region 241 are close to the inner and outer boundaries of the second electrode layer 260, respectively. For example, when projected along the thickness direction of the piezoelectric material layer 250, the width of the envelope line enclosing the inner boundary of the first hollow region 241 and the inner boundary of the second electrode layer 260 is less than or equal to 5% of the width of the second electrode layer 260 at the corresponding position, and the width of the envelope line enclosing the outer boundary of the first hollow region 241 and the outer boundary of the second electrode layer 260 is less than or equal to 5% of the width of the second electrode layer 260 at the corresponding position.

[0104] In this embodiment, the degree of misalignment between the inner boundaries of the first electrode layer 240 and the second electrode layer 260 and the degree of misalignment between the outer boundaries are reduced, which is beneficial to further enhance the vibration amplitude of the piezoelectric diaphragm through the first electrode layer 240 and the second electrode layer 260, thereby improving the output sound pressure level and reducing the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20 under the same output sound pressure level requirement.

[0105] Reference Figure 8 In some embodiments, a spiral groove 251 is provided on the surface of the piezoelectric material layer 250 facing the first electrode layer 240. The inner and outer boundaries of the spiral groove 251 are respectively positioned opposite to the inner and outer boundaries of the first hollow area 241. It can be understood that, when projected along the thickness direction of the piezoelectric material layer 250, the inner and outer boundaries of the spiral groove 251 are close to the inner and outer boundaries of the first hollow area 241. For example, when projected along the thickness direction of the piezoelectric material layer 250, the width of the envelope line that encloses the inner boundary of the spiral groove 251 and the inner boundary of the first hollow area 241 is less than or equal to 5% of the width of the first hollow area 241 at the corresponding position, and the width of the envelope line that encloses the outer boundary of the spiral groove 251 and the outer boundary of the first hollow area 241 is less than or equal to 5% of the width of the first hollow area 241 at the corresponding position.

[0106] In this embodiment, the degree of misalignment between the inner boundaries of the spiral groove 251 and the first hollow area 241, and the degree of misalignment between the outer boundaries are reduced. This is beneficial to further enhance the vibration amplitude of the piezoelectric diaphragm through the first electrode layer 240, thereby improving the output sound pressure level and reducing the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20 under the same output sound pressure level requirements.

[0107] In some embodiments, in the same radius of curvature direction of the first electrode layer 240, the radius difference between the inner boundary of the first hollow region 241 and the inner boundary of the spiral groove 251 is less than or equal to 10% of the radius of curvature of the inner boundary of the spiral groove 251, so as to further enhance the vibration amplitude of the piezoelectric diaphragm; wherein, the radius difference can be further set to be less than or equal to 5% of the radius of curvature of the inner boundary of the spiral groove 251. In some embodiments, in the same radius of curvature direction of the first electrode layer 240, the radius difference between the outer boundary of the first hollow region 241 and the outer boundary of the spiral groove 251 is less than or equal to 10% of the radius of curvature of the outer boundary of the spiral groove 251, so as to further enhance the vibration amplitude of the piezoelectric diaphragm; wherein, the radius difference can be further set to be less than or equal to 5% of the radius of curvature of the outer boundary of the spiral groove 251.

[0108] Therefore, the inner boundaries of the second electrode layer 260, the spiral groove 251, and the first hollow area 241 can be correspondingly set. For example, the width of the envelope line enclosing the inner boundaries of the second electrode layer 260, the spiral groove 251, and the first hollow area 241 can be set to 5% of the width of the second electrode layer 260 at the corresponding position, to further enhance the vibration amplitude of the piezoelectric diaphragm. Furthermore, the outer boundaries of the second electrode layer 260, the spiral groove 251, and the first hollow area 241 can also be correspondingly set. For example, the width of the envelope line enclosing the outer boundaries of the second electrode layer 260, the spiral groove 251, and the first hollow area 241 can be set to 5% of the width of the second electrode layer 260 at the corresponding position, to further enhance the vibration amplitude of the piezoelectric diaphragm.

[0109] For example, in some embodiments, in the same radius of curvature direction of the second electrode layer 260, the radius difference between the inner boundary of the first hollow region 241 and the inner boundary of the second electrode layer 260 is less than or equal to 10% of the radius of curvature of the inner boundary of the second electrode layer 260; for example, this radius difference can be further set to be less than or equal to 5% of the radius of curvature of the inner boundary of the second electrode layer 260. In some embodiments, in the same radius of curvature direction of the second electrode layer 260, the radius difference between the outer boundary of the first hollow region 241 and the outer boundary of the second electrode layer 260 is less than or equal to 10% of the radius of curvature of the outer boundary of the second electrode layer 260; for example, this radius difference can be further set to be less than or equal to 5% of the radius of curvature of the outer boundary of the second electrode layer 260.

[0110] Each of the above embodiments is beneficial to further increase the vibration amplitude of the piezoelectric diaphragm, thereby improving the output sound pressure level, and reducing the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20 under the same output sound pressure level requirements.

[0111] Reference Figure 8 In some embodiments, the thickness T of the portion of the piezoelectric material layer 250 disposed opposite to the spiral groove 251 is greater than or equal to 5 micrometers and less than or equal to 10 micrometers, thereby improving the vibration performance of the piezoelectric material layer 250 while maintaining high structural strength, thereby increasing the output sound pressure level of the MEMS speaker core and extending its service life.

[0112] Reference Figure 10 and Figure 11In some embodiments, the piezoelectric material layer 250 is provided with a connecting through-hole 252, and the piezoelectric diaphragm further includes a first electrode terminal 242, which is at least partially disposed on the wall of the connecting through-hole 252; one end of the first electrode terminal 242 is connected to the first electrode layer 240, and the other end of the first electrode terminal 242 is spaced apart from the second electrode layer 260. The first electrode terminal 242 can be formed by sputtering onto the wall of the connecting through-hole 252.

[0113] In this embodiment, the connection via 252 and the first electrode terminal 242 increases the wiring space of the first electrode layer 240, thereby facilitating the connection between the first electrode layer 240 and external wires. Furthermore, the connection via 252 allows the intermediate process structures of the first electrode terminal 242 and the second electrode layer 260 to be formed in the same process (subsequently separated by etching or other processing methods), thus improving the overall fabrication efficiency of the MEMS speaker core.

[0114] Of course, in other embodiments, the first electrode layer 240 may not be provided with the above-mentioned connection through hole 252 and first electrode terminal 242, but the connection with the external wire can be achieved through the side surface of the first electrode layer 240 or other positions. This embodiment does not limit this.

[0115] Reference Figure 7 and Figure 10 In some embodiments, the cross-section of the connecting through hole 252 is set to a rectangle or a rounded rectangle, and the length of the cross-section of the connecting through hole 252 is greater than or equal to 50 micrometers and less than or equal to 100 micrometers, thereby facilitating the direct sputtering formation of the first electrode terminal 242; in some embodiments, the width of the cross-section of the connecting through hole 252 is greater than or equal to 50 micrometers and less than or equal to 100 micrometers, thereby facilitating the direct sputtering formation of the first electrode terminal 242.

[0116] Reference Figure 7 and Figure 10 In some embodiments, the first electrode terminal 242 includes a cylindrical segment, which is at least partially embedded in the connecting through-hole 252. Specifically, the cylindrical segment of the first electrode terminal 242 can be formed by sputtering or other methods, and the cylindrical segment of the first electrode terminal 242 is at least partially embedded in the connecting through-hole 252. The inclusion of a cylindrical segment in the first electrode terminal 242, with at least a partial embedding within the connecting through-hole 252, reduces the material consumption of the first electrode terminal 242 and lowers the overall material cost of the MEMS speaker core.

[0117] For the MEMS speaker module 20 in the above embodiment, under a driving voltage of 5V and at a position 10 mm away from the MEMS speaker module 20, the SPL curve of the MEMS speaker module 20 is simulated. The sound pressure level of the MEMS speaker module 20 at 8kHz can reach 112dB, which is greater than 102dB in the related technology.

[0118] Reference Figure 12 In some alternative embodiments, the piezoelectric diaphragm includes two symmetrically arranged diaphragm segments 201, which can be understood as a portion of the piezoelectric diaphragm; for example, Figure 12 The upper and lower membrane segments 201 are symmetrically arranged. Each membrane segment 201 includes a first electrode layer 240, a piezoelectric material layer 250, and a second electrode layer 260. It can be understood that the shapes of the first electrode layer 240, the piezoelectric material layer 250, and the second electrode layer 260 in the two membrane segments 201 are respectively set to be symmetrical.

[0119] In this embodiment, the piezoelectric diaphragm includes two symmetrically arranged diaphragm segments 201, which is beneficial to improving the output sound pressure level. Thus, under the same output sound pressure level requirement, it is beneficial to reduce the overall area of ​​the piezoelectric diaphragm and reduce the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0120] Reference Figure 12 In some embodiments, in two membrane segments 201 (e.g. Figure 12 In the upper and lower membrane segments 201, the spiral outer ends of the two second electrode layers 260 are connected and the spiral outer ends of the second hollow area 262 are connected. The spiral inner portions of the two second electrode layers 260 are arranged opposite each other, thereby further improving the output sound pressure level and further reducing the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0121] Among them, reference Figure 12 The inner spiral portions of the two second electrode layers 260 can be connected to each other, thereby reducing the area of ​​the piezoelectric diaphragm; or, refer to Figure 13 The two second electrode layers 260 are formed by spacing the inner spiral portions of the two layers. Figure 13 The spacing L in the middle further enhances the output sound pressure level.

[0122] Reference Figure 12 or Figure 13 In some embodiments, the piezoelectric diaphragm includes two symmetrically arranged segments 202, for example... Figure 12 (or Figure 13The left and right segment groups 202 are symmetrically arranged in the middle; the segment group 202 includes two symmetrically arranged diaphragm segments 201 (the segment group 202 can be understood as a part of the piezoelectric diaphragm, but the area is larger than the area of ​​a single diaphragm segment 201), thereby further improving the output sound pressure level.

[0123] Reference Figure 12 or Figure 13 In two symmetrically arranged fragment groups 202, for example in Figure 12 (or Figure 13 In the left and right segment groups 202 of the MEMS speaker, the outer spiral end of the second electrode layer 260 faces each other, while the inner spiral end of the second electrode layer 260 faces away from each other, thereby further improving the output sound pressure level and further reducing the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0124] Reference Figure 14 In some alternative embodiments, at least three sequentially connected electrode segments 261 are respectively configured as circular or elliptical shapes to form a second hollow region 262. Specifically, the second hollow region 262 can be formed through the gaps between the circular (or elliptical) segments. In this case, the characteristic dimensions of the first electrode segment 261, the second electrode segment 261, and the third electrode segment 261 respectively include the radius of curvature R1 of the first electrode segment 261, the radius of curvature R2 of the second electrode segment 261, and the radius of curvature R3 of the third electrode segment 261. In this case, the difference between the sum of the radius of curvature R1 and the radius of curvature R2 of the first electrode segment 261 and the radius of curvature R3 of the third electrode segment 261 is less than or equal to the aforementioned first preset value; it can be understood that the sum of the radius of curvature R1 and the radius of curvature R2 of the first electrode segment 261 is approximately equal to the radius of curvature R3 of the third electrode segment 261.

[0125] In this embodiment, at least three sequentially connected electrode segments 261 are respectively set to be circular or elliptical and form a second hollow area 262, which is beneficial to improve the output sound pressure level; thus, under the same output sound pressure level requirement, it is beneficial to reduce the overall area of ​​the piezoelectric diaphragm and reduce the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0126] Reference Figure 14 In some embodiments, the piezoelectric diaphragm includes at least two membrane segments 201. Each membrane segment 201 includes a first electrode layer 240, a piezoelectric material layer 250, and a second electrode layer 260. Each membrane segment 201 can be understood as a portion of the piezoelectric diaphragm. The membrane segments 201 are circumferentially distributed around the thickness direction of the piezoelectric material layer 250, for example... Figure 14 The three membrane segments 201 are circumferentially distributed along the W1 direction.

[0127] In this embodiment, the membrane segment 201 is circumferentially distributed around the thickness direction of the piezoelectric material layer 250, which is beneficial to further improve the output sound pressure level and further reduce the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0128] Reference Figure 14 In some embodiments, at least some of the electrode segments 261 have increased feature dimensions (e.g., the radii of curvature R1, R2, and R3 in the figure increase sequentially) along the direction toward the circumferential distribution center of the membrane segment 201, which is beneficial to further improve the output sound pressure level and further reduce the volume of the MEMS speaker core and the corresponding MEMS speaker module 20 as a whole.

[0129] Reference Figure 14 In some embodiments, the second electrode layer 260 further includes a connecting strip 268, which extends along the outer envelope of the electrode segments 261 of two adjacent film segments 201. It is understood that the connecting strip 268 is also connected to the corresponding electrode segment 261. The connecting strip 268 and the electrode segments 261 can be formed by simultaneous fabrication processes, such as simultaneous sputtering and etching processes. In this embodiment, the connecting strip 268 extending along the outer envelope of the electrode segments 261 of two adjacent film segments 201 is beneficial for improving the overall vibration stability of the piezoelectric diaphragm.

[0130] Reference Figure 15 In some alternative embodiments, the second electrode layer 260 includes at least three interconnected triangular frames 269, with the same edge of the third triangular frame 269 connecting the edges of the first and second triangular frames 269 to form a second cutout region 262; see reference. Figure 15 The dotted lines in the lower middle section represent the edges of three connected triangular frames 269: the first electrode segment 261, the second electrode segment 261, and the third electrode segment 261. The characteristic dimensions of the first, second, and third electrode segments 261 respectively include the side lengths of the frames of the first, second, and third electrode segments 261. At this time, the difference between the sum of the side lengths of the first and second electrode segments 261 and the side length of the third electrode segment 261 is less than or equal to the aforementioned first preset value; this can be understood as the sum of the side lengths of the first and second electrode segments 261 being approximately equal to the side length of the third electrode segment 261.

[0131] In this embodiment, the same frame edge of the third triangular frame 269 connects the frame edge of the first triangular frame 269 and the frame edge of the second triangular frame 269 to form the second hollow area 262, which is beneficial to improve the output sound pressure level; thus, under the same output sound pressure level requirement, it is beneficial to reduce the overall area of ​​the piezoelectric diaphragm, and to reduce the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0132] Reference Figure 15 In some embodiments, the piezoelectric diaphragm includes two segments 201, each segment including a first electrode layer 240, a piezoelectric material layer 250, and a second electrode layer 260. Segment 201 can be understood as a portion of the piezoelectric diaphragm. Segment 201 is centrally symmetrical about the thickness direction of the piezoelectric material layer 250, for example... Figure 15 The two diaphragm segments 201 are circumferentially distributed along the W2 direction and are centrally symmetrical, which is beneficial to further improve the output sound pressure level.

[0133] Reference Figure 15 In some embodiments, the edges of the largest triangular frames 269 in each of the two diaphragm segments 201 are connected, which helps to further improve the output sound pressure level. Specifically, the second electrode layers 260 in the two diaphragm segments 201 can be arranged as a parallelogram.

[0134] Reference Figure 16 and Figure 17 This application provides a method for fabricating a MEMS loudspeaker core, the method comprising the following steps:

[0135] Step S100: A first electrode intermediate layer 21 is formed on the support block 23. For example, the first electrode intermediate layer 21 is formed by sputtering. At this time, the first electrode intermediate layer 21 is in the shape of an integral sheet. For example, a first electrode intermediate layer 21 of Au (gold) material with a thickness of 100 nanometers to 500 nanometers can be sputtered on the support block 23 of Si (silicon) material.

[0136] Step S200: A piezoelectric material layer 250 is formed on the intermediate layer 21 of the first electrode; for example, the piezoelectric material layer 250 is formed by sputtering, at which time the piezoelectric material layer 250 is in the form of an integral sheet; for example, a layer of PZT piezoelectric ceramic material piezoelectric material layer 250 can be sputtered on the intermediate layer 21 of the first electrode, and then the thickness of the piezoelectric material layer 250 can be reduced to 10 micrometers to 20 micrometers by grinding, polishing and other processing methods.

[0137] In step S300, a second electrode intermediate layer 22 is formed on the piezoelectric material layer 250; for example, the second electrode intermediate layer 22 is formed by sputtering, and the second electrode intermediate layer 22 is in the form of an integral sheet; for example, a second electrode intermediate layer 22 of Au (gold) material with a thickness of 100 nanometers to 500 nanometers can be sputtered on the piezoelectric material layer 250.

[0138] In step S400, the second electrode intermediate layer 22 is processed into a second electrode layer 260 having a second hollow area 262. The second electrode layer 260 includes at least three electrode segments 261 connected in sequence. Among the three adjacent electrode segments 261, the difference between the sum of the feature size of the first electrode segment 261 and the feature size of the second electrode segment 261 and the feature size of the third electrode segment 261 is less than or equal to the first preset value mentioned above.

[0139] In step S500, the first electrode intermediate layer 21 is processed into a first electrode layer 240 having a first hollow region 241 (specifically, this can be processed by etching or other methods), and the first hollow region 241 is disposed opposite to the second electrode layer 260. Further, the first electrode intermediate layer 21 can be processed into the shape of the second electrode layer 260 described in the above embodiment.

[0140] This embodiment can improve the output sound pressure level of the prepared MEMS speaker core and the corresponding MEMS speaker module 20, thereby reducing the overall area of ​​the piezoelectric diaphragm and the overall volume of the MEMS speaker core and the corresponding MEMS speaker module 20 under the same output sound pressure level requirement; this embodiment can also improve the overall fabrication efficiency of the MEMS speaker core and the corresponding MEMS speaker module 20.

[0141] Reference Figure 16 and Figure 18 In some embodiments, after the step of forming the second electrode intermediate layer 22 on the piezoelectric material layer 250, the method for fabricating the MEMS speaker core further includes the following steps:

[0142] In step S600, the aforementioned through-structure 265 is fabricated on the second electrode intermediate layer 22 or the second electrode layer 260. The through-structure 265 penetrates the second electrode layer 260 and the piezoelectric material layer 250, thereby increasing the vibration amplitude of the piezoelectric diaphragm and improving the overall fabrication efficiency. The through-structure 265 can be formed by etching, cutting, or other methods. Furthermore, the fabrication method of the MEMS speaker core may further include processing the through-structure 265 into the shape of the through-structure 265 described in the above embodiment.

[0143] In some embodiments, the step of processing the second electrode intermediate layer 22 into a second electrode layer 260 having a second hollow region 262 (step S400 above) includes:

[0144] The second electrode terminal 267 is fabricated from the intermediate layer 22 of the second electrode and connected to the second electrode layer 260, thereby further improving the fabrication efficiency.

[0145] In some embodiments, the step of processing the first electrode intermediate layer 21 into a first electrode layer 240 having a first hollow region 241 (step S500 above) includes:

[0146] The support block 23, the first electrode intermediate layer 21, and the piezoelectric material layer 250 are processed, for example, by etching, so that the support block 23 forms a support frame 230 and the piezoelectric material layer 250 forms a spiral groove 251 facing the surface of the first electrode layer 240. The inner and outer boundaries of the spiral groove 251 are respectively aligned with the inner and outer boundaries of the first hollow area 241, thereby further improving the fabrication efficiency. The fabrication method of the MEMS speaker core may further include processing the support block 23, the first electrode intermediate layer 21, and the piezoelectric material layer 250 into the shapes of the support frame 230, the first electrode layer 240, and the piezoelectric material layer 250 as described in the above embodiment.

[0147] Reference Figure 16 and Figure 18 In some embodiments, after the step of forming a piezoelectric material layer 250 on the first electrode intermediate layer 21, the method for fabricating the MEMS speaker core further includes the following steps: Step S250, forming a connection via 252 on the piezoelectric material layer 250, the connection via 252 extending to the first electrode intermediate layer 21, for example, the connection via 252 can be formed by etching.

[0148] The step of forming a second electrode intermediate layer 22 on the piezoelectric material layer 250 includes: forming at least a portion of a first electrode terminal 242 on the wall of the connecting through hole 252, one end of the first electrode terminal 242 being connected to the first electrode intermediate layer 21, for example, by sputtering to form at least a portion of the first electrode terminal 242 on the wall of the connecting through hole 252.

[0149] In this embodiment, a connecting through hole 252 is first formed on the piezoelectric material layer 250, and then at least a portion of the first electrode terminal 242 is formed on the hole wall of the connecting through hole 252, which is beneficial to further improve the preparation efficiency.

[0150] The method for fabricating the MEMS speaker core may further include processing the connection through hole 252 into the shape of the connection through hole 252 described in the above embodiment.

[0151] In some embodiments, the step of processing the second electrode intermediate layer 22 into a second electrode layer 260 having a second hollow region 262 (step S400 above) includes:

[0152] The other end of the first electrode terminal 242 is spaced apart from the second electrode layer 260, which helps to further improve the overall fabrication efficiency of the MEMS speaker core.

[0153] It is understood that since the fabrication method of the MEMS speaker core, the MEMS speaker module, and the electronic device adopt all the technical solutions of all the embodiments of the above-mentioned MEMS speaker core, they have at least all the beneficial effects brought about by the technical solutions of the above-mentioned embodiments, which will not be elaborated here.

[0154] The above description is merely a specific embodiment of this application. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the protection scope of this application. The protection scope of this application should be determined by the protection scope of the claims.

Claims

1. A MEMS loudspeaker core, characterized in that, The MEMS speaker core includes a support frame and a piezoelectric diaphragm, the edge of which is connected to the support frame. The piezoelectric diaphragm includes: A first electrode layer, the first electrode layer being connected to the support frame, the first electrode layer having a first hollow area; A piezoelectric material layer, which is used to convert electrical energy into sound pressure, is disposed on the first electrode layer; The piezoelectric material layer has a spiral groove on the surface of the first electrode layer. The inner and outer boundaries of the spiral groove are respectively opposite to the inner and outer boundaries of the first hollow area. The thickness of the piezoelectric material layer opposite to the spiral groove is greater than or equal to 5 micrometers and less than or equal to 10 micrometers. A second electrode layer is disposed on the piezoelectric material layer. The second electrode layer includes at least three sequentially connected electrode segments forming a second hollow area. The second electrode layer is disposed opposite to the first hollow area. In the three adjacent electrode segments, the difference between the sum of the feature dimensions of the first and second electrode segments and the feature dimension of the third electrode segment is less than or equal to a first preset value, and the first preset value is less than or equal to 10% of the feature dimension of the third electrode segment. The second electrode layer has a through structure that penetrates the second electrode layer and the piezoelectric material layer. The through structure is connected to the first hollow area. The through structure separates the outer spiral end of the second electrode layer and connects it to the inner spiral end of the second electrode layer.

2. The MEMS speaker core as described in claim 1, characterized in that, The second electrode layer extends spirally along the surface plane of the piezoelectric material layer to form the second hollow region. The second electrode layer includes at least three electrode segments connected sequentially in a spiral outward direction. Among the three adjacent electrode segments connected sequentially in a spiral outward direction, the characteristic dimensions of the first electrode segment, the second electrode segment, and the third electrode segment respectively include the radius of curvature of the first electrode segment, the radius of curvature of the second electrode segment, and the radius of curvature of the third electrode segment.

3. The MEMS speaker core as described in claim 2, characterized in that, The second electrode layer includes an inner boundary and an outer boundary relative to the helical center; The inner boundary includes at least three inner segments connected sequentially in a spiral outward direction; in the three adjacent inner segments connected sequentially in a spiral outward direction, the characteristic dimensions of the first electrode segment, the second electrode segment, and the third electrode segment respectively include the radius of curvature of the first inner segment, the radius of curvature of the second inner segment, and the radius of curvature of the third inner segment.

4. The MEMS speaker core as described in claim 3, characterized in that, The outer boundary includes at least three outer segments connected sequentially in a spiral outward direction; in the three adjacent outer segments connected sequentially in a spiral outward direction, the characteristic dimensions of the first, second, and third electrode segments respectively include the radius of curvature of the first, second, and third outer segments.

5. The MEMS speaker core as described in claim 4, characterized in that, The first inner segment, the second inner segment, and the third inner segment are respectively configured to correspond to the first outer segment, the second outer segment, and the third outer segment. The curvature radius of the first inner segment, the second inner segment, and the third inner segment is smaller than the curvature radius of the first outer segment, the second outer segment, and the third outer segment, respectively.

6. The MEMS speaker core as described in claim 1, characterized in that, The through-structure includes a spiral slit that extends spirally along the surface plane of the piezoelectric material layer.

7. The MEMS speaker core as described in claim 6, characterized in that, The spiral seam includes at least three seam segments connected sequentially in a spiral outward direction; in the three adjacent seam segments connected sequentially in a spiral outward direction, the difference between the sum of the curvature radii of the first seam segment and the curvature radii of the second seam segment and the curvature radii of the third seam segment is less than or equal to a second preset value.

8. The MEMS speaker core as described in claim 7, characterized in that, The first preset value is less than or equal to 10% of the feature size of the third electrode segment; And / or, the second preset value is less than or equal to 10% of the radius of curvature of the third said gap segment; And / or, the thickness of the second electrode layer is greater than or equal to 100 nanometers and less than or equal to 500 nanometers; And / or, the thickness of the piezoelectric material layer is greater than or equal to 10 micrometers and less than or equal to 20 micrometers; And / or, the thickness of the first electrode layer is greater than or equal to 100 nanometers and less than or equal to 500 nanometers; And / or, the width of the spiral slit is less than or equal to 5 micrometers.

9. The MEMS speaker core as described in claim 1, characterized in that, The surface plane of the piezoelectric material layer facing the second electrode layer is further provided with a second electrode terminal, and the second electrode terminal is connected to the second electrode layer; The second electrode terminal is connected to one of the outer portion of the outer end of the second electrode layer and the inner portion of the outer end of the second electrode layer.

10. The MEMS loudspeaker core as described in any one of claims 2 to 5, characterized in that, The first hollow area extends spirally along the other surface plane of the piezoelectric material layer, and the inner and outer boundaries of the first hollow area are respectively positioned opposite to the inner and outer boundaries of the second electrode layer.

11. The MEMS speaker core as described in claim 10, characterized in that, In the same radius of curvature direction of the first electrode layer, the radius difference between the inner boundary of the first hollow area and the inner boundary of the spiral groove is less than or equal to 10% of the radius of curvature of the inner boundary of the spiral groove; and / or, in the same radius of curvature direction of the first electrode layer, the radius difference between the outer boundary of the first hollow area and the outer boundary of the spiral groove is less than or equal to 10% of the radius of curvature of the outer boundary of the spiral groove; And / or, the thickness of the portion of the piezoelectric material layer disposed opposite to the spiral groove is greater than or equal to 5 micrometers and less than or equal to 10 micrometers; And / or, in the same radius of curvature direction of the second electrode layer, the radius difference between the inner boundary of the first hollow region and the inner boundary of the second electrode layer is less than or equal to 10% of the radius of curvature of the inner boundary of the second electrode layer; And / or, in the same radius of curvature direction of the second electrode layer, the radius difference between the outer boundary of the first hollow region and the outer boundary of the second electrode layer is less than or equal to 10% of the radius of curvature of the outer boundary of the second electrode layer.

12. The MEMS speaker core as described in claim 1, characterized in that, The piezoelectric material layer is provided with a connecting through hole, and the piezoelectric diaphragm further includes a first electrode terminal, which is at least partially disposed on the hole wall of the connecting through hole; one end of the first electrode terminal is connected to the first electrode layer, and the other end of the first electrode terminal is spaced apart from the second electrode layer.

13. The MEMS speaker core as described in claim 12, characterized in that, The cross-section of the connecting through hole is set to a rectangle or a rounded rectangle; the length of the cross-section of the connecting through hole is greater than or equal to 50 micrometers and less than or equal to 100 micrometers, and / or the width of the cross-section of the connecting through hole is greater than or equal to 50 micrometers and less than or equal to 100 micrometers; And / or, the first electrode terminal includes a cylindrical section, which is at least partially embedded in the connection through hole.

14. The MEMS loudspeaker core as described in any one of claims 2 to 5, characterized in that, The piezoelectric diaphragm includes two symmetrically arranged diaphragm segments, each segment comprising a first electrode layer, a piezoelectric material layer, and a second electrode layer.

15. The MEMS speaker core as described in claim 14, characterized in that, In the two membrane segments, the spiral outer ends of the two second electrode layers are connected and the spiral outer ends of the second hollowed-out regions are connected, and the spiral inner portions of the two second electrode layers are arranged opposite to each other.

16. The MEMS speaker core as described in claim 15, characterized in that, The inner spiral portions of the two second electrode layers are connected to each other, or the inner spiral portions of the two second electrode layers are spaced apart.

17. The MEMS speaker core as described in claim 15, characterized in that, The piezoelectric diaphragm includes two symmetrically arranged segments, each segment comprising two symmetrically arranged diaphragm segments; in the two symmetrically arranged segments, the outer spiral ends of the second electrode layer face each other, and the inner spiral ends of the second electrode layer face away from each other.

18. The MEMS speaker core as described in claim 1, characterized in that, At least three sequentially connected electrode segments are respectively configured as circular or elliptical and form the second hollow area. The characteristic dimensions of the first electrode segment, the second electrode segment, and the third electrode segment respectively include the radius of curvature of the first electrode segment, the radius of curvature of the second electrode segment, and the radius of curvature of the third electrode segment.

19. The MEMS speaker core as described in claim 18, characterized in that, The piezoelectric diaphragm includes at least two segments, each segment comprising a first electrode layer, the piezoelectric material layer, and a second electrode layer, and the segments are circumferentially distributed around the thickness direction of the piezoelectric material layer.

20. The MEMS speaker core as described in claim 19, characterized in that, Along the direction toward the circumferential distribution center of the membrane segment, at least a portion of the electrode segment has an increased feature size; And / or, the second electrode layer further includes a connecting strip that extends along the outer envelope of the electrode segments of two adjacent membrane segments.

21. The MEMS speaker core as described in claim 1, characterized in that, The second electrode layer includes at least three connected triangular frames, with the same frame edge of the third triangular frame connecting the frame edge of the first triangular frame and the frame edge of the second triangular frame to form the second hollow area; The first electrode segment, the second electrode segment, and the third electrode segment are respectively configured as the frame sides of three connected triangular frames. The feature dimensions of the first electrode segment, the second electrode segment, and the third electrode segment respectively include the frame side length of the first electrode segment, the frame side length of the second electrode segment, and the frame side length of the third electrode segment.

22. The MEMS speaker core as described in claim 21, characterized in that, The piezoelectric diaphragm comprises two segments, each segment including a first electrode layer, a piezoelectric material layer, and a second electrode layer. The segments are centrally symmetrical about the thickness of the piezoelectric material layer. In the two segments, the sides of the largest triangular frame are connected.

23. A MEMS loudspeaker module, characterized in that, The MEMS speaker module includes a module circuit board, a module housing, and a MEMS speaker core as described in any one of claims 1 to 22. The end of the support frame facing away from the piezoelectric diaphragm is connected to the module circuit board, and the second electrode layer and the first electrode layer are electrically connected to the module circuit board, respectively. The module housing has a housing sound outlet, and the MEMS speaker core is at least partially disposed within the module housing.

24. An electronic device, characterized in that, The electronic device includes a device housing and a MEMS speaker module as described in claim 23, wherein the device housing is provided with a device sound outlet and the MEMS speaker module is disposed within the device housing.

25. A method for fabricating a MEMS loudspeaker core, characterized in that, The preparation method includes the following steps: A first electrode intermediate layer is formed on the support block; A piezoelectric material layer is formed on the intermediate layer of the first electrode; A second electrode intermediate layer is formed on the piezoelectric material layer; The second electrode intermediate layer is processed into a second electrode layer with a second hollow area, the second electrode layer comprising at least three electrode segments connected in sequence; in the three adjacent electrode segments, the difference between the sum of the feature dimensions of the first electrode segment and the feature dimensions of the second electrode segment and the feature dimension of the third electrode segment is less than or equal to a first preset value, the first preset value being less than or equal to 10% of the feature dimension of the third electrode segment; The first electrode intermediate layer is processed into a first electrode layer with a first hollow area, and the first hollow area is disposed opposite to the second electrode layer; The piezoelectric material layer has a spiral groove on the surface of the first electrode layer. The inner and outer boundaries of the spiral groove are respectively opposite to the inner and outer boundaries of the first hollow area. The thickness of the piezoelectric material layer opposite to the spiral groove is greater than or equal to 5 micrometers and less than or equal to 10 micrometers. A through-structure is formed on the intermediate layer of the second electrode. The through-structure penetrates the second electrode layer and the piezoelectric material layer. The through-structure is connected to the first hollow area. The through-structure separates the outer spiral end of the second electrode layer and connects the inner spiral end of the second electrode layer.

26. The method for fabricating a MEMS loudspeaker core as described in claim 25, characterized in that, After the step of forming the second electrode intermediate layer on the piezoelectric material layer, the method for fabricating the MEMS speaker core further includes the following steps: A through-structure is formed on the intermediate layer of the second electrode or the second electrode layer, the through-structure penetrating the second electrode layer and the piezoelectric material layer.

27. The method for fabricating a MEMS loudspeaker core as described in claim 25 or 26, characterized in that, The step of processing the second electrode intermediate layer into a second electrode layer having a second hollow region includes: The second electrode terminal is fabricated in the intermediate layer of the second electrode, and the second electrode terminal is connected to the second electrode layer.

28. The method for fabricating a MEMS loudspeaker core as described in claim 25, characterized in that, The step of processing the first electrode intermediate layer into a first electrode layer having a first hollow region includes: The support block, the first electrode intermediate layer, and the piezoelectric material layer are processed to form a support frame, and the piezoelectric material layer forms a spiral groove facing the surface of the first electrode layer. The inner and outer boundaries of the spiral groove are respectively set opposite to the inner and outer boundaries of the first hollow area.

29. The method for fabricating a MEMS loudspeaker core as described in claim 25, characterized in that, After the step of forming a piezoelectric material layer on the first electrode intermediate layer, the method for fabricating the MEMS speaker core further includes the following step: forming a connection via on the piezoelectric material layer, wherein the connection via extends to the first electrode intermediate layer; The step of forming a second electrode intermediate layer on the piezoelectric material layer includes: At least a portion of a first electrode terminal is formed on the wall of the connecting through hole, and one end of the first electrode terminal is connected to the first electrode intermediate layer.

30. The method for fabricating a MEMS loudspeaker core as described in claim 29, characterized in that, The step of processing the second electrode intermediate layer into a second electrode layer having a second hollow region includes: The other end of the first electrode terminal is spaced apart from the second electrode layer.

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