Piezoelectric loudspeaker and preparation method thereof

Abstract

The invention discloses a piezoelectric loudspeaker and a preparation method thereof, and belongs to the technical field of semiconductors. The piezoelectric loudspeaker comprises a piezoelectric structure which comprises a first electrode, a piezoelectric layer, a second electrode and a flexible substrate which are stacked; wherein the piezoelectric structure comprises a bottom section and a side wall section which are enclosed to form a cavity; the first electrode, the piezoelectric layer, the second electrode and the flexible substrate in the bottom section and the side wall section are sequentially arranged in the direction away from the cavity, and the first electrode of the bottom section is electrically connected with the first electrode of the side wall section. The first electrode of the bottom section is electrically connected with the second electrode of the side wall section. The vibration amplitude of the film can be greatly increased, the sound pressure level under low-frequency response is improved, and low-frequency distortion is reduced.

Description

Technical Field

[0001] This application belongs to the field of semiconductor technology, and in particular relates to a piezoelectric loudspeaker and its preparation method. Background Technology

[0002] MEMS loudspeakers are products manufactured using microelectromechanical systems technology. Their core components, such as actuators / drivers and diaphragms, are fabricated on semiconductor materials. MEMS loudspeakers utilize several technological approaches, including capacitive (electrostatic), thermoacoustic, magnetostrictive, and piezoelectric MEMS loudspeakers. Piezoelectric MEMS loudspeakers utilize the inverse piezoelectric effect of piezoelectric materials. By applying a voltage to a piezoelectric ceramic material, such as lead zirconate titanate (PZT), mechanical deformation is caused, which in turn pushes air to produce sound.

[0003] However, the small size of MEMS loudspeakers makes it physically difficult to generate large air displacements. Low-frequency sound generation typically requires significant diaphragm movement and sufficient airflow, but MEMS loudspeakers, due to their size limitations, struggle to provide adequate low-frequency output, resulting in insufficient sound pressure levels in the low-frequency response. Furthermore, to increase volume at low frequencies, MEMS loudspeakers may require greater vibration amplitude, but their vibration system is susceptible to thermal effects, electrical distortion, and mechanical nonlinearity, leading to low-frequency distortion. Summary of the Invention

[0004] This application aims to address at least one of the technical problems existing in the prior art. To this end, this application proposes a piezoelectric loudspeaker and a method for manufacturing the same, which can greatly increase the vibration amplitude of the thin film, improve the sound pressure level at low frequencies, and reduce low-frequency distortion.

[0005] In a first aspect, this application provides a piezoelectric loudspeaker, comprising:

[0006] A piezoelectric structure includes a first electrode, a piezoelectric layer, a second electrode, and a flexible substrate stacked together.

[0007] The piezoelectric structure includes a bottom section and a sidewall section that enclose a cavity; the first electrode, the piezoelectric layer, the second electrode, and the flexible substrate in the bottom section and the sidewall section are arranged sequentially in a direction away from the cavity, and the first electrode in the bottom section and the first electrode in the sidewall section are electrically connected, and the second electrode in the bottom section and the second electrode in the sidewall section are electrically connected.

[0008] According to the piezoelectric loudspeaker of this application, the bottom section and side wall section of the piezoelectric structure enclose a three-dimensional cavity, and the bottom section and side wall section have a first electrode, a piezoelectric layer, a second electrode and a flexible substrate arranged sequentially from the inside to the outside. That is, the bottom and side wall of the cavity both have a first electrode, a piezoelectric layer, a second electrode and a flexible substrate, so that the bottom and side wall of the cavity can vibrate with the change of voltage, and the vibration amplitude of the flexible substrate is large, thereby greatly increasing the vibration amplitude of the thin film, increasing the sound pressure level at low frequency response and reducing low frequency distortion; moreover, the sound wave propagates in the three-dimensional cavity and is reflected at the cavity boundary, causing the sound pressure to be superimposed to form interference, thereby increasing the vibration amplitude at the same frequency and increasing the sound pressure level.

[0009] According to one embodiment of this application, the piezoelectric loudspeaker further includes:

[0010] A cover layer covers the top of the cavity; the cover layer has multiple through holes.

[0011] According to one embodiment of this application, the covering layer is a flexible layer.

[0012] According to one embodiment of this application, the piezoelectric layer includes a piezoelectric pattern layer and a dielectric layer; the piezoelectric pattern layer includes a plurality of piezoelectric patterns spaced apart, and the dielectric layer is located between the plurality of piezoelectric patterns;

[0013] The bottom section and the sidewall section each have the piezoelectric pattern.

[0014] According to one embodiment of this application, the piezoelectric layer is a flexible piezoelectric material layer.

[0015] According to one embodiment of this application, the piezoelectric structure further includes a connecting section, the connecting section having the same stacking direction as the film layer in the bottom section, and the first electrode of the connecting section being electrically connected to the first electrode of the bottom section, and the first electrode of the connecting section being electrically connected to the second electrode of the bottom section.

[0016] The connection section has an opening that penetrates the first electrode and the piezoelectric layer.

[0017] According to one embodiment of this application, the piezoelectric loudspeaker further includes:

[0018] An insulating layer is located between the connection section and the sidewall section.

[0019] According to one embodiment of this application, the insulating layer is a flexible layer.

[0020] According to one embodiment of this application, the piezoelectric loudspeaker further includes:

[0021] A support layer is located on the side of the piezoelectric structure near the bottom section; the support layer has a cavity corresponding to the bottom section.

[0022] According to one embodiment of this application, the material of the flexible substrate includes at least one of PDMS and PI.

[0023] According to one embodiment of this application, the cavity is a cylinder, a single vertebra, or a double vertebra; and / or,

[0024] The cross-section of the cavity is circular, elliptical, or polygonal.

[0025] According to one embodiment of this application, the piezoelectric loudspeaker further includes:

[0026] The circuit board is electrically connected to the first electrode and the second electrode, respectively.

[0027] The housing, the piezoelectric structure, and the circuit board are located within the housing.

[0028] Secondly, this application provides a method for manufacturing a piezoelectric loudspeaker, comprising:

[0029] A piezoelectric structure is formed, the piezoelectric structure comprising a first electrode, a piezoelectric layer, a second electrode, and a flexible substrate stacked together; wherein the piezoelectric structure includes a bottom section and a sidewall section;

[0030] The sidewall section is bent so that the sidewall section and the bottom section enclose a cavity; the first electrode, the piezoelectric layer, the second electrode and the flexible substrate in the bottom section and the sidewall section are arranged sequentially in a direction away from the cavity, and the first electrode of the bottom section and the first electrode of the sidewall section are electrically connected, and the second electrode of the bottom section and the second electrode of the sidewall section are electrically connected.

[0031] According to one embodiment of this application, forming the piezoelectric structure includes:

[0032] A conductive layer is formed on one side of the first hard substrate;

[0033] A first electrode layer is formed on one side of the second hard substrate;

[0034] The conductive layer is temporarily bonded to the first electrode layer;

[0035] Remove the second hard substrate;

[0036] An initial piezoelectric layer, a second electrode layer, and a flexible substrate layer are sequentially formed on the side of the first electrode layer away from the conductive layer.

[0037] The flexible substrate layer, the second electrode layer, the initial piezoelectric layer, and the first electrode layer are etched to form the flexible substrate, the second electrode, the piezoelectric layer, and the first electrode, respectively.

[0038] The first electrode is debonded to the conductive layer.

[0039] According to one embodiment of this application, bending the sidewall section to form a cavity by the sidewall section and the bottom section includes:

[0040] Place the mold in the bottom section;

[0041] The sidewall section is bent toward the mold so that the sidewall section fits into the sidewall of the mold.

[0042] Remove the mold, and let the side wall section and the bottom section enclose the cavity.

[0043] The above-described one or more technical solutions in the embodiments of this application have at least one of the following technical effects:

[0044] The bottom and sidewall sections of the piezoelectric structure enclose a three-dimensional cavity. The bottom and sidewall sections have a first electrode, a piezoelectric layer, a second electrode, and a flexible substrate arranged sequentially from the inside out. That is, both the bottom and sidewalls of the cavity have a first electrode, a piezoelectric layer, a second electrode, and a flexible substrate, which allows the bottom and sidewalls of the cavity to vibrate with changes in voltage. The flexible substrate has a large vibration amplitude, which greatly increases the vibration amplitude of the thin film, improves the sound pressure level at low frequencies, and reduces low-frequency distortion. Moreover, the sound waves propagate in the three-dimensional cavity and are reflected at the cavity boundary, causing the sound pressure to superimpose and form interference, thereby increasing the vibration amplitude and improving the sound pressure level at the same frequency.

[0045] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0046] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0047] Figure 1 This is a cross-sectional schematic diagram of the piezoelectric loudspeaker provided in an embodiment of this application;

[0048] Figure 2 This is one of the structural schematic diagrams of the piezoelectric loudspeaker provided in the embodiments of this application;

[0049] Figure 3This is a second schematic diagram of the structure of the piezoelectric loudspeaker provided in the embodiments of this application;

[0050] Figure 4 This is the third schematic diagram of the structure of the piezoelectric loudspeaker provided in the embodiments of this application;

[0051] Figure 5 This is a simulation diagram of a piezoelectric loudspeaker in the embodiments of this application, related technologies, and comparative embodiments;

[0052] Figure 6 This is a comparison graph of the sound pressure level curves of piezoelectric loudspeakers in the embodiments of this application and related technologies;

[0053] Figure 7 This is one of the comparison graphs of the sound pressure level curves of the piezoelectric loudspeaker in the embodiments of this application and the comparative embodiments;

[0054] Figure 8 This is the second comparison diagram of the sound pressure level curves of the piezoelectric loudspeaker in the embodiments of this application and the comparative embodiments;

[0055] Figure 9 This is a schematic flowchart of the method for manufacturing a piezoelectric loudspeaker provided in an embodiment of this application;

[0056] Figure 10 This is one of the structural schematic diagrams in the method for manufacturing a piezoelectric loudspeaker provided in the embodiments of this application;

[0057] Figure 11 This is the second structural schematic diagram of the method for manufacturing a piezoelectric loudspeaker provided in the embodiments of this application;

[0058] Figure 12 This is the third structural schematic diagram of the method for manufacturing a piezoelectric loudspeaker provided in the embodiments of this application;

[0059] Figure 13 This is the fourth structural schematic diagram of the piezoelectric loudspeaker manufacturing method provided in the embodiments of this application;

[0060] Figure 14 This is the fifth structural schematic diagram of the piezoelectric loudspeaker manufacturing method provided in the embodiments of this application;

[0061] Figure 15 This is the sixth structural schematic diagram of the method for manufacturing a piezoelectric loudspeaker provided in the embodiments of this application;

[0062] Figure 16 This is the seventh structural schematic diagram of the piezoelectric loudspeaker manufacturing method provided in the embodiments of this application;

[0063] Figure 17 This is the eighth schematic diagram of the structure in the method for manufacturing a piezoelectric loudspeaker provided in the embodiments of this application;

[0064] Figure 18 This is the ninth structural schematic diagram of the method for manufacturing a piezoelectric loudspeaker provided in the embodiments of this application;

[0065] Figure 19 This is the tenth structural schematic diagram of the method for manufacturing a piezoelectric loudspeaker provided in the embodiments of this application;

[0066] Figure 20 This is eleventh of the structural schematic diagrams in the method for manufacturing a piezoelectric loudspeaker provided in the embodiments of this application;

[0067] Figure 21 This is the twelfth schematic diagram of the structure in the method for manufacturing a piezoelectric loudspeaker provided in the embodiments of this application;

[0068] Figure 22 This is schematic diagram thirteen of the structural diagrams in the method for manufacturing a piezoelectric loudspeaker provided in the embodiments of this application;

[0069] Figure 23 This is the fourteenth schematic diagram of the structure in the method for preparing a piezoelectric loudspeaker provided in the embodiments of this application. Detailed Implementation

[0070] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0071] The piezoelectric loudspeaker and its manufacturing method provided in this application are described below with reference to the accompanying drawings.

[0072] Figures 1 to 4 This is a schematic diagram of the structure of a piezoelectric loudspeaker provided in an embodiment of this application. The piezoelectric loudspeaker can be a piezoelectric MEMS loudspeaker.

[0073] like Figure 1 and Figure 2 As shown, the piezoelectric loudspeaker provided in this application embodiment includes a piezoelectric structure 1, which includes a first electrode 11, a piezoelectric layer 12, a second electrode 13 and a flexible substrate 14 stacked together.

[0074] The piezoelectric structure 1 includes a bottom section 1a and a sidewall section 1b that enclose and form a cavity 10. The first electrode 11, the piezoelectric layer 12, the second electrode 13, and the flexible substrate 14 in the bottom section 1a and the sidewall section 1b are arranged sequentially in the direction away from the cavity, and the first electrode 11 of the bottom section 1a and the first electrode 11 of the sidewall section 1b are electrically connected, and the second electrode 13 of the bottom section 1a and the second electrode 13 of the sidewall section 1b are electrically connected.

[0075] The bottom section 1a and the side wall section 1b enclose and form a cavity, that is, the bottom section 1a is located at the bottom of the cavity, and the side wall section 1b is arranged around the periphery of the cavity, making the cavity a three-dimensional cavity.

[0076] The film layers in the bottom section 1a and the sidewall section 1b have the same stacking order. That is, the bottom section 1a includes a first electrode 11, a piezoelectric layer 12, a second electrode 13 and a flexible substrate 14 arranged sequentially in the direction away from the cavity (i.e. from the inside to the outside), and the sidewall section 1b includes a first electrode 11, a piezoelectric layer 12, a second electrode 13 and a flexible substrate 14 arranged sequentially from the inside to the outside.

[0077] The first electrode 11 in the bottom section 1a and the first electrode 13 in the sidewall section 1b can be electrically connected through physical contact. Similarly, the second electrode 13 in the bottom section 1a and the second electrode 13 in the sidewall section 1b can be electrically connected through physical contact. Both the first electrode 11 and the second electrode 13 can be flexible electrodes, meaning they can be made of flexible electrode materials. This allows the first electrode 11 in both the bottom section 1a and the sidewall section 1b to be integrally formed continuous electrodes, and the second electrode 13 in both sections to be integrally formed continuous electrodes. For example, the material of the first electrode 11 can include metals such as copper or aluminum. The material of the second electrode 13 can also include metals such as copper or aluminum.

[0078] In this embodiment, the bottom section 1a and the sidewall section 1b of the piezoelectric structure enclose a three-dimensional cavity 10. Both the bottom section 1a and the sidewall section 1b have a first electrode 11, a piezoelectric layer 12, a second electrode 13, and a flexible substrate 14. That is, the bottom and sidewall of the cavity 10 both have the first electrode 11, the piezoelectric layer 12, the second electrode 13, and the flexible substrate 14, so that the bottom and sidewall of the cavity 10 can vibrate with the change of voltage, acting together on the air to increase the vibration amplitude of the thin film. Compared with the silicon substrate in related technologies, the vibration amplitude of the flexible substrate 14 is larger, further increasing the vibration amplitude of the thin film, thereby increasing the sound pressure level at low frequency response and reducing low frequency distortion. Moreover, the cavity 10 is a three-dimensional cavity, and the sound waves propagate in the three-dimensional cavity and reflect at the boundary of the cavity 10, causing the sound pressure to superimpose and form interference, thereby increasing the vibration amplitude at the same frequency and increasing the sound pressure level.

[0079] In some embodiments, the material of the flexible substrate 14 may include at least one of PDMS (polydimethylsiloxane) and PI (polyimide). The flexible substrate 14 may also include other flexible materials, which are not specifically limited herein.

[0080] In some embodiments, combined with Figure 3 and Figure 4As shown, the piezoelectric loudspeaker also includes a cover layer 4 that covers the top of the cavity 10. The cover layer 4 has multiple through holes.

[0081] The shape and size of the covering layer 4 can match the shape and size of the bottom section 1a. The covering layer 4 covers the top of the cavity 10, and the edge of the covering layer 4 can be adhered to the top of the side wall section 1b, so that the covering layer 4, the side wall section 1b and the bottom section 1a enclose the cavity 10 therein.

[0082] The cover layer 4 has multiple through holes. These through holes can be arranged in an array or in other ways. They can be located near the center of the cover layer 4 or at other locations within the cover layer 4. It should be noted that the number, location, and distribution of the through holes in the cover layer 4 can be set according to actual needs and are not specifically limited here.

[0083] This embodiment reduces reflection loss, enhances sound wave directionality, and optimizes acoustic performance by covering the top of the cavity 10 with a perforated covering layer 4.

[0084] In some embodiments, the cover layer 4 is a flexible layer. The material of the cover layer 4 may include at least one of PDMS and PI. The material of the cover layer 4 may also include other types of flexible materials, which are not specifically limited here. The materials of the cover layer 4 and the flexible substrate 14 may be the same or different.

[0085] In this embodiment, the cover layer 4 is set as a flexible layer, which can further enhance the low-frequency response and reduce low-frequency distortion.

[0086] In some embodiments, the piezoelectric layer 12 can be a flexible piezoelectric material layer, meaning that the entire film layer of the piezoelectric layer 12 is made of flexible piezoelectric material. In this embodiment, the entire film layer of the piezoelectric layer 12 is a sound-generating layer, meaning that the piezoelectric layer 12 can undergo slight deformation (expansion or contraction) when subjected to an alternating electric field to drive the surrounding air to vibrate and generate sound waves. The piezoelectric layer 12 in the bottom section 1a and the sidewall section 1b can be a continuously formed film layer. For example, the material of the piezoelectric layer 12 may include PVDF (polyvinylidene fluoride), etc.

[0087] In some embodiments, such as Figure 1 As shown, the piezoelectric layer 12 may include a piezoelectric pattern layer 121 and a dielectric layer 122. The piezoelectric pattern layer 121 includes a plurality of piezoelectric patterns spaced apart, and the dielectric layer 122 is located between the plurality of piezoelectric patterns. The bottom section 1a and the sidewall section 1b each have a piezoelectric pattern.

[0088] The piezoelectric layer 12 is a composite film layer comprising a piezoelectric pattern layer 121 and a dielectric layer 122. The piezoelectric pattern layer 121 can be a non-flexible piezoelectric material layer, meaning it can be made of a non-flexible piezoelectric material. For example, the material of the piezoelectric pattern layer 121 can include PZT (lead zirconate titanate). The dielectric layer 122 is made of a dielectric material, such as silicon oxide or silicon nitride. The dielectric layer 122 is used to isolate the first electrode 11 and the second electrode 13. The piezoelectric pattern layer 121 is a sound-generating functional layer, and the dielectric layer 122 is a non-sound-generating functional layer.

[0089] To ensure that both the bottom section 1a and the sidewall section 1b have piezoelectric material, the piezoelectric pattern layer 121 may include multiple piezoelectric patterns, with the bottom section 1a and the sidewall section 1b each having at least one piezoelectric pattern.

[0090] The area of ​​the piezoelectric pattern in the bottom section 1a can be less than or equal to the area of ​​the bottom section 1a, and the area of ​​the piezoelectric pattern in the sidewall section 1b can be less than or equal to the area of ​​the sidewall section 1b. To avoid short circuit caused by contact between the first electrode 11 and the second electrode 13, a dielectric layer 122 is provided between the multiple piezoelectric patterns to isolate the first electrode 11 and the second electrode 13.

[0091] In some embodiments, the piezoelectric structure further includes a connection section 1c, which has the same stacking direction as the film layers in the bottom section 1a. A first electrode 11 in the connection section 1c is electrically connected to a first electrode 11 in the bottom section 1a, and a second electrode 13 in the connection section 1c is electrically connected to a second electrode 13 in the bottom section 1a. The connection section 1c has an opening 15 extending through the first electrode 11 and the piezoelectric layer 12. The opening 15 exposes the second electrode 13 for electrical connection to other devices.

[0092] The connecting section 1c can be located on the side of the sidewall section 1b away from the cavity 10. The connecting section 1c can be located on the same plane as the bottom section 1a, and the stacking direction of the film layers in the connecting section 1c and the bottom section 1a is the same. For example, the bottom section 1a includes a first electrode 11, a piezoelectric layer 12, a second electrode 13 and a flexible substrate 14 arranged sequentially in the direction away from the cavity 10 (e.g., from top to bottom), and the connecting section 1c includes a first electrode 11, a piezoelectric layer 12, a second electrode 13 and a flexible substrate 14 arranged sequentially from top to bottom.

[0093] The first electrode 11 of the bottom section 1a and the first electrode 11 of the connecting section 1c can be electrically connected through physical contact, so that the first electrodes 11 in the bottom section 1a, sidewall section 1b, and connecting section 1c are electrically connected to each other. The second electrode 13 of the bottom section 1a and the connecting section 1c can be electrically connected through physical contact, so that the second electrodes 13 in the bottom section 1a, sidewall section 1b, and connecting section 1c are electrically connected to each other. The first electrodes 11 in the bottom section 1a, sidewall section 1b, and connecting section 1c can be integrally formed continuous electrodes, and the second electrodes 13 in the bottom section 1a, sidewall section 1b, and connecting section 1c can be integrally formed continuous electrodes.

[0094] The connection section 1c has an opening 15 that penetrates the first electrode 11 and the piezoelectric layer 12. When the piezoelectric layer 12 includes a piezoelectric pattern layer 121 and a dielectric layer 122, the opening 15 penetrates both the first electrode 11 and the dielectric layer 122. The bottom of the opening 15 is the second electrode 13, meaning the opening 15 exposes the second electrode 13, so that electrical signals can be provided to the first electrode 11 and the second electrode 13 in the bottom section 1a and the sidewall section 1b through the first electrode 11 and the second electrode 13 in the connection section 1c.

[0095] In some embodiments, combined with Figure 4 As shown, the piezoelectric loudspeaker also includes an insulating layer 5, which is located between the connecting section 1c and the sidewall section 1b.

[0096] Since the connecting section 1c is located on the side of the sidewall section 1b away from the cavity 10, the connecting section 1c needs to penetrate through each film layer of the sidewall section 1b and connect to the bottom section 1a. In order to prevent the first electrode 11 in the connecting section 1c from contacting the second electrode 13 in the sidewall section 1b, an insulating layer 5 can be provided between the connecting section 1c and the sidewall section 1b to isolate the first electrode 11 in the connecting section 1c from the second electrode 13 in the sidewall section 1b.

[0097] In some embodiments, the bottom segment 1a and the sidewall segment 1b are partially in physical contact, such that the first electrode 11 in the bottom segment 1a and the sidewall segment 1b are electrically connected, and the second electrode 13 in the bottom segment 1a and the sidewall segment 1b are electrically connected. The remaining portions of the bottom segment 1a and the sidewall segment 1b are not in physical contact, such that there is a gap between the bottom segment 1a and the sidewall segment 1b, and the insulating layer 5 is also filled in the gap between the bottom segment 1a and the sidewall segment 1b.

[0098] In some embodiments, the sidewall segment 1b has an annular structure with a notch (gap), i.e., the sidewall segment 1b is a non-closed structure. The insulating layer 5 also fills the gap in the sidewall segment 1b.

[0099] In some embodiments, the sidewall section 1b includes a plurality of sidewall sub-segments distributed circumferentially along the cavity 10. Each sidewall sub-segment is in physical contact with the bottom section 1a, such that the first electrode 11 in each sidewall sub-segment is electrically connected to the first electrode 11 in the bottom section 1a, and the second electrode 13 in each sidewall sub-segment is electrically connected to the second electrode 13 in the bottom section 1a. A gap exists between adjacent sidewall sub-segments, and the insulating layer 5 fills the gap between adjacent sidewall sub-segments.

[0100] In some embodiments, the insulating layer is a flexible layer. The material of the insulating layer 5 may include at least one of PDMS and PI. The material of the insulating layer 5 may also include other types of flexible materials, which are not specifically limited here. The materials of the insulating layer 5, the cover layer 4, and the flexible substrate 14 may be the same or different.

[0101] In some embodiments, the cavity 10 is a cylinder, a single cone, or a double cone, and the shape of the cavity 10 may also include other shapes, which are not specifically limited here.

[0102] In some embodiments, the cross-section of the cavity 10 is circular, elliptical, or polygonal, and the cross-section of the cavity 10 may also be other shapes, which are not specifically limited here.

[0103] The bottom section 1a and the side wall section 1b have different shapes, and the cavity 10 formed by the bottom section 1a and the side wall section 1b has different shapes. The shapes of the bottom section 1a and the side wall section 1b can be set according to actual needs to form a cavity 10 of the required shape.

[0104] In some embodiments, such as Figure 1 and Figure 2 As shown, the piezoelectric loudspeaker also includes a support layer 3, which is located on the side of the piezoelectric structure near the bottom section 1a. The support layer 3 has a cavity corresponding to the bottom section 1a.

[0105] The support layer 3 is used to provide support for the piezoelectric structure to fix it in place. The flexible substrate 14 in the bottom section 1a and the connecting section 1c can be disposed on the support layer 3.

[0106] The support layer 3 has a cavity that penetrates through it. The orthographic projection of the cavity onto the plane containing the bottom section 1a can lie within the bottom section 1a, ensuring that the bottom section 1a can be fixed to the support layer 3. The size and shape of the cavity can be set according to actual needs and are not specifically limited here.

[0107] In this embodiment, a cavity is provided in the support layer 3, which can enhance the sound pressure level, optimize the frequency response characteristics, and further improve the acoustic performance.

[0108] In some embodiments, the piezoelectric loudspeaker further includes a circuit board electrically connected to the first electrode 11 and the second electrode 13, respectively.

[0109] The circuit board is electrically connected to the first electrode 11 and the second electrode 13 in the connection section 1c, thereby achieving electrical connection with the first electrode 11 and the second electrode 13 in the bottom section 1a and the sidewall section 1b. The circuit board is used to provide electrical signals to the first electrode 11 and the second electrode 13.

[0110] In some embodiments, the piezoelectric loudspeaker also includes a housing, with the piezoelectric structure 1 and the circuit board located inside the housing.

[0111] The performance of the piezoelectric loudspeaker provided in this embodiment is analyzed using COMSOL simulation method and compared with piezoelectric loudspeakers in related technologies.

[0112] Figure 5 (a) is a schematic diagram of a piezoelectric loudspeaker model in the related technology, which uses a silicon wafer as a substrate and PZT as a piezoelectric material with a side length of 2mm. Figure 5 (b) is a schematic diagram of the 711 ear canal model from the COMSOL case library to compare the performance of different piezoelectric loudspeakers. Figure 5 (c) and Figure 5 (d) is a schematic diagram of the piezoelectric loudspeaker model in the comparative embodiment. Figure 5 (c) is a square-shaped piezoelectric loudspeaker. Figure 5 (c) is a circular piezoelectric loudspeaker, which uses PDMS as a flexible substrate and PZT as a piezoelectric material. Figure 5 (e) and Figure 5 (f) is a schematic diagram of a piezoelectric loudspeaker model in an embodiment of this application. Figure 5 (e) is a piezoelectric loudspeaker with a cubic cavity. Figure 5 (f) is a piezoelectric loudspeaker with a cylindrical cavity, which uses PDMS as a flexible substrate and PZT as a piezoelectric material.

[0113] Different piezoelectric loudspeakers were placed under the ear canal model, and the sound pressure level on the upper plane was measured and compared. The frequency of the piezoelectric loudspeakers was also changed. Figure 5 The gradient bars in the image represent the sound pressure level, or the intensity of the sound. The darker the blue, the lower the sound intensity, i.e., the lower the sound pressure level; the darker the red, the higher the sound intensity, i.e., the higher the sound pressure level.

[0114] Depend on Figure 5As can be seen, at the same frequency, the piezoelectric loudspeaker in the related technology is blue, and the blue is deeper, indicating the lowest sound pressure level. The piezoelectric loudspeaker in the comparative embodiment is blue, but the blue is relatively lighter, indicating that the flexible substrate can increase the diaphragm vibration amplitude and thus the sound pressure level. The bottom of the piezoelectric loudspeaker in this embodiment is red, indicating the presence of a three-dimensional cavity, and the flexible substrate on both the bottom and sidewalls of the three-dimensional cavity can greatly increase the diaphragm vibration amplitude and generate a higher sound pressure level.

[0115] Additionally, refer to Figures 6 to 8 , Figure 6 This is a comparison chart of the sound pressure level curves of the piezoelectric loudspeaker with a cubic cavity and the piezoelectric loudspeaker with a cylindrical cavity in this embodiment with those of piezoelectric loudspeakers in related technologies. Figure 7 This is a comparison graph of the sound pressure level curves of the piezoelectric loudspeaker with a cubic cavity in this embodiment and the piezoelectric loudspeaker with a square cavity in the comparative embodiment. Figure 8 This is a comparison chart of the sound pressure level curves of a piezoelectric loudspeaker with a cylindrical cavity in this embodiment and a piezoelectric loudspeaker with a circular cavity in the comparative embodiment.

[0116] Depend on Figure 6 As can be seen, compared to related technologies, the piezoelectric loudspeaker in this embodiment has a significantly higher sound pressure level at low frequencies. Figure 7 and Figure 8 As can be seen, the three-dimensional cavity in this embodiment can effectively improve the sound pressure level output by the piezoelectric speaker.

[0117] In summary, this embodiment employs a piezoelectric MEMS loudspeaker, which offers advantages over traditional loudspeakers (such as dynamic loudspeakers) in terms of small size, light weight, and low power consumption. Furthermore, this embodiment uses a flexible substrate as the substrate for the generating film, which, compared to the use of silicon or silicon dioxide as substrates in related technologies, increases the vibration amplitude of the film and improves the sound pressure level of the piezoelectric loudspeaker. Moreover, the bottom and sidewall sections of the piezoelectric structure in this embodiment enclose a three-dimensional cavity, and each section has a first electrode, a piezoelectric layer, a second electrode, and a flexible substrate arranged sequentially from the inside out. This means that both the bottom and sidewalls of the cavity have the first electrode, piezoelectric layer, second electrode, and flexible substrate, allowing the bottom and sidewalls of the cavity to vibrate with voltage changes, further increasing the film vibration amplitude, improving the sound pressure level at low frequencies, and reducing low-frequency distortion. Additionally, the sound waves propagate within the three-dimensional cavity and reflect at the cavity boundaries, causing the sound pressure to superimpose and form interference, thereby increasing the vibration amplitude at the same frequency and further improving the sound pressure level.

[0118] Accordingly, this application also provides a method for manufacturing a piezoelectric loudspeaker, which can manufacture the piezoelectric loudspeaker described in the above embodiments.

[0119] like Figure 9As shown, the method for fabricating the epitaxial structure provided in this application includes steps 110 and 120.

[0120] Step 110: Form a piezoelectric structure, which includes a first electrode, a piezoelectric layer, a second electrode, and a flexible substrate stacked together; wherein the piezoelectric structure includes a bottom section and a sidewall section.

[0121] In some embodiments, a piezoelectric structure is formed, including:

[0122] A conductive layer is formed on one side of the first hard substrate;

[0123] A first electrode layer is formed on one side of the second hard substrate;

[0124] The conductive layer is temporarily bonded to the first electrode layer;

[0125] Remove the second hard substrate;

[0126] An initial piezoelectric layer, a second electrode layer, and a flexible substrate layer are sequentially formed on the side of the first electrode layer away from the conductive layer.

[0127] The flexible substrate layer, the second electrode layer, the initial piezoelectric layer, and the first electrode layer are etched to form the flexible substrate, the second electrode, the piezoelectric layer, and the first electrode, respectively.

[0128] The first electrode is debonded to the conductive layer.

[0129] like Figure 10 As shown, a first hard substrate 51 and a second hard substrate 52 are provided. The materials of the first hard substrate 51 and the second hard substrate 52 may include materials such as silicon.

[0130] Then, as Figure 11 As shown, a conductive layer 53 is formed on one side of the first hard substrate 51 and a first electrode layer 11' is formed on one side of the second hard substrate 52 using a thin film deposition process. The conductive layer 53 and the first electrode layer 11' can be made of the same material, such as copper or other metals.

[0131] Then, as Figure 12 As shown, the conductive layer 52 is temporarily bonded to the first electrode layer 11'. Figure 13 As shown, a thinning and polishing process is used to remove the second hard substrate 52 to expose the side of the first electrode layer 11' away from the conductive layer 53.

[0132] The initial piezoelectric layer may include a piezoelectric patterned layer and a dielectric layer. For example... Figure 14 As shown, a piezoelectric material layer 121' is first formed on the side of the first electrode layer 11' facing away from the conductive layer 53 using processes such as magnetron sputtering. The material of the piezoelectric material layer 121' may include PZT, etc. Then, as... Figure 15As shown, the piezoelectric material layer 121' is etched to form a piezoelectric pattern layer 121. The piezoelectric pattern layer 121 may include multiple piezoelectric patterns spaced apart. Then, as... Figure 16 As shown, a dielectric layer 122 is formed between multiple piezoelectric patterns.

[0133] The piezoelectric structure includes a connecting section. Then, as... Figure 17 As shown, the dielectric layer 122 and the first electrode layer 11' in the connection section are etched to form an opening 15 that penetrates the dielectric layer 122 and the first electrode layer 11', that is, the connection section has an opening 15 that exposes the first electrode layer 11'. Then, photoresist 54 is filled into the opening 15.

[0134] Then, as Figure 18 As shown, a second electrode layer 13' is formed using a thin-film deposition process, covering a piezoelectric pattern layer 122, a dielectric layer 121, and a photoresist 54. The material of the second electrode layer 13' may include a metal such as copper.

[0135] Then, as Figure 19 As shown, a flexible substrate layer 14' is formed on the side of the second electrode layer 13' facing away from the initial piezoelectric layer. The material of the flexible substrate layer 14' may include at least one of PDMS and PI.

[0136] Then, combine Figure 20 As shown, the flexible substrate layer 14', the second electrode layer 13', the initial piezoelectric layer, and the first electrode layer 11' are etched as a whole to form the desired shape, which facilitates subsequent enclosure to form a cavity. Specifically, the flexible substrate layer 14' is etched to form the flexible substrate 14, the second electrode layer 13' is etched to form the second electrode 13, the initial piezoelectric layer is etched to form the piezoelectric layer 12, and the first electrode layer 11' is etched to form the first electrode 11.

[0137] Then as Figure 21 As shown, the first electrode 11 is debonded from the conductive layer 53 to remove the first hard substrate 51 and the conductive layer 53. Then, as... Figure 22 As shown, the photoresist 54 in the opening 15 is removed.

[0138] Step 120: Bend the sidewall section to form a cavity by enclosing the sidewall section and the bottom section; the first electrode, piezoelectric layer, second electrode and flexible substrate in the bottom section and the sidewall section are arranged in sequence in the direction away from the cavity, and the first electrode of the bottom section is connected to the first electrode in the sidewall section, and the second electrode of the bottom section is connected to the second electrode of the sidewall section.

[0139] It should be noted that the piezoelectric structure formed in step 110 is a planar structure. The shapes of the bottom and sidewall sections of the piezoelectric structure can be designed according to the shape of the cavity to be formed. By bending the sidewall sections of the piezoelectric structure, the bottom and sidewall sections are enclosed to form a cavity, thus transforming the piezoelectric structure from a planar structure into a three-dimensional structure.

[0140] In some embodiments, bending the sidewall section to allow the sidewall section and the bottom section to enclose a cavity includes:

[0141] Place the mold in the bottom section;

[0142] The side wall section is bent toward the mold so that it fits into the side wall of the mold.

[0143] Remove the mold and allow the side wall section and bottom section to enclose and form a cavity.

[0144] Combination Figure 23 As shown, mold 55 is placed at the bottom section 1a, with the orthographic projection of mold 55 onto the plane of bottom section 1a overlapping with bottom section 1a. The size and shape of mold 55 match the size and shape of the cavity to be formed. Then, sidewall section 1b is bent so that it fits against the sidewall of mold 55.

[0145] Then, combine Figure 1 As shown, mold 55 is removed, so that sidewall section 1b and bottom section 1a enclose a cavity 10, and the piezoelectric structure constitutes a three-dimensional piezoelectric structure 1. The connecting section 1c has an opening 15, which exposes the second electrode 13 so as to provide electrical signals to the first electrode 11 and the second electrode 13 of the connecting section 1c.

[0146] Then, the piezoelectric structure 1 is fixed to the support layer 3 on the side near the bottom section 1b, that is, the flexible substrate 14 in the bottom section 1a is fixed to the support layer 3, so as to fix the piezoelectric speaker in its required working environment.

[0147] The shapes of the planar piezoelectric structures formed in step 110 and the shapes of the cavities enclosed in step 120 vary, resulting in different shapes for the three-dimensional piezoelectric structures. For example, the overall shape of the bottom segment 1a and the sidewall segment 1b in the planar piezoelectric structure formed in step 110 can be a cross shape, such as... Figure 3 As shown, the cavity 10 formed in step 120 is rectangular, and the three-dimensional piezoelectric structure 1 is also rectangular. For example, in the planar piezoelectric structure formed in step 110, the bottom section 1a can be circular, and the sidewall section 1b can be rectangular, such as... Figure 4 As shown, the cavity 10 formed by step 120 is cylindrical, and the three-dimensional piezoelectric structure 1 is cylindrical.

[0148] In some embodiments, there is a gap between the bottom section 1a and the sidewall section 1b; and / or, the sidewall section 1b is annular with a gap; and / or, the sidewall section 1b includes a plurality of sidewall sub-segments distributed circumferentially around the cavity 10, with gaps between adjacent sidewall sub-segments; and / or, there is a gap between the connecting section 1c and the sidewall section 1b.

[0149] Combination Figure 4 As shown, prior to the step of removing the mold, the preparation method may further include filling the gap with an insulating layer 5.

[0150] The insulating layer 5 can be a flexible layer, and the material of the insulating layer 5 can include at least one of PDMS and PI.

[0151] In some embodiments, combined with Figure 4 and Figure 5 As shown, after bending the sidewall section in step 120 to form a cavity by enclosing the sidewall section and the bottom section, the preparation method may further include covering the top of the cavity 10 with a covering layer 4 having multiple through holes.

[0152] The cover layer 4 can be a flexible layer, and the material of the cover layer 4 can include at least one of PDMS and PI.

[0153] According to the piezoelectric loudspeaker manufacturing method provided in the embodiments of this application, a three-dimensional cavity is formed by enclosing the bottom section and the side wall section of the piezoelectric structure. The bottom section and the side wall section have a first electrode, a piezoelectric layer, a second electrode, and a flexible substrate arranged sequentially from the inside to the outside. That is, the bottom and side walls of the cavity both have a first electrode, a piezoelectric layer, a second electrode, and a flexible substrate, so that the bottom and side walls of the cavity can vibrate with the change of voltage. Moreover, the vibration amplitude of the flexible substrate is large, thereby greatly increasing the vibration amplitude of the thin film, increasing the sound pressure level under low frequency response, and reducing low frequency distortion. Furthermore, the sound wave propagates in the three-dimensional cavity and is reflected at the cavity boundary, causing the sound pressure to be superimposed to form interference, thereby increasing the vibration amplitude and increasing the sound pressure level at the same frequency.

[0154] The terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and are not limited in number; for example, a first object can be one or more.

[0155] In the description of this application, "multiple" means two or more.

[0156] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0157] Although embodiments of this application have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the claims and their equivalents.

Claims

1. A piezoelectric loudspeaker, characterized in that, include: A piezoelectric structure includes a first electrode, a piezoelectric layer, a second electrode, and a flexible substrate stacked together. The piezoelectric structure includes a bottom section and a sidewall section that enclose a cavity; the first electrode, the piezoelectric layer, the second electrode, and the flexible substrate in the bottom section and the sidewall section are arranged sequentially in a direction away from the cavity, and the first electrode in the bottom section and the first electrode in the sidewall section are electrically connected, and the second electrode in the bottom section and the second electrode in the sidewall section are electrically connected.

2. The piezoelectric loudspeaker according to claim 1, characterized in that, The piezoelectric loudspeaker also includes: A cover layer covers the top of the cavity; the cover layer has multiple through holes.

3. The piezoelectric loudspeaker according to claim 2, characterized in that, The covering layer is a flexible layer.

4. The piezoelectric loudspeaker according to claim 1, characterized in that, The piezoelectric layer includes a piezoelectric pattern layer and a dielectric layer; the piezoelectric pattern layer includes a plurality of piezoelectric patterns spaced apart, and the dielectric layer is located between the plurality of piezoelectric patterns; The bottom section and the sidewall section each have the piezoelectric pattern.

5. The piezoelectric loudspeaker according to claim 1, characterized in that, The piezoelectric layer is a flexible piezoelectric material layer.

6. The piezoelectric loudspeaker according to claim 1, characterized in that, The piezoelectric structure further includes a connecting section, the connecting section having the same stacking direction as the film layers in the bottom section, and the first electrode of the connecting section being electrically connected to the first electrode of the bottom section, and the second electrode of the connecting section being electrically connected to the second electrode of the bottom section. The connection section has an opening that penetrates the first electrode and the piezoelectric layer.

7. The piezoelectric loudspeaker according to claim 6, characterized in that, The piezoelectric loudspeaker also includes: An insulating layer is located between the connection section and the sidewall section.

8. The piezoelectric loudspeaker according to claim 7, characterized in that, The insulating layer is a flexible layer.

9. The piezoelectric loudspeaker according to claim 1, characterized in that, The piezoelectric loudspeaker also includes: A support layer is located on the side of the piezoelectric structure near the bottom section; the support layer has a cavity corresponding to the bottom section.

10. The piezoelectric loudspeaker according to claim 1, characterized in that, The flexible substrate is made of at least one of PDMS and PI.

11. The piezoelectric loudspeaker according to claim 1, characterized in that, The cavity is a cylindrical body, a single vertebral body, or a double vertebral body; and / or, The cross-section of the cavity is circular, elliptical, or polygonal.

12. The piezoelectric loudspeaker according to any one of claims 1-11, characterized in that, The piezoelectric loudspeaker also includes: The circuit board is electrically connected to the first electrode and the second electrode, respectively. The housing, the piezoelectric structure, and the circuit board are located within the housing.

13. A method for manufacturing a piezoelectric loudspeaker, characterized in that, include: A piezoelectric structure is formed, the piezoelectric structure comprising a first electrode, a piezoelectric layer, a second electrode, and a flexible substrate stacked together; wherein the piezoelectric structure includes a bottom section and a sidewall section; The sidewall section is bent so that the sidewall section and the bottom section enclose a cavity; the first electrode, the piezoelectric layer, the second electrode and the flexible substrate in the bottom section and the sidewall section are arranged sequentially in a direction away from the cavity, and the first electrode of the bottom section and the first electrode of the sidewall section are electrically connected, and the second electrode of the bottom section and the second electrode of the sidewall section are electrically connected.

14. The method for manufacturing a piezoelectric loudspeaker according to claim 13, characterized in that, The formation of the piezoelectric structure includes: A conductive layer is formed on one side of the first hard substrate; A first electrode layer is formed on one side of the second hard substrate; The conductive layer is temporarily bonded to the first electrode layer; Remove the second hard substrate; An initial piezoelectric layer, a second electrode layer, and a flexible substrate layer are sequentially formed on the side of the first electrode layer away from the conductive layer. The flexible substrate layer, the second electrode layer, the initial piezoelectric layer, and the first electrode layer are etched to form the flexible substrate, the second electrode, the piezoelectric layer, and the first electrode, respectively. The first electrode is debonded to the conductive layer.

15. The method for manufacturing a piezoelectric loudspeaker according to claim 13 or 14, characterized in that, The bending of the sidewall section to form a cavity by the sidewall section and the bottom section includes: Place the mold in the bottom section; The sidewall section is bent toward the mold so that the sidewall section fits into the sidewall of the mold. Remove the mold, and let the side wall section and the bottom section enclose the cavity.

Images