Transduction assembly, MEMS piezoelectric micro loudspeaker and electronic equipment

Abstract

The utility model relates to the technical field of semiconductors, in particular to a transduction assembly, an MEMS piezoelectric micro loudspeaker and electronic equipment, and the transduction assembly comprises a vibrating diaphragm unit which comprises at least two passivation layers which are stacked; and the piezoelectric composite unit is arranged between two adjacent passivation layers in the vibrating diaphragm unit. The vibrating diaphragm unit in the transduction assembly comprises the two passivation layers, compared with a vibrating diaphragm comprising a supporting layer structure in the prior art, the number of supporting layers is reduced, the preparation technological process is simplified, the production cost is reduced, the rigidity of the vibrating diaphragm unit is reduced, and therefore when the vibrating diaphragm unit is driven by piezoelectricity, larger offset displacement can be generated, and the energy conversion efficiency is improved. Therefore, a larger sound pressure level is output. Besides, the transduction assembly is of a sandwich structure composed of the vibrating diaphragm unit and the piezoelectric composite unit, the residual stress in the MEMS technological process can be effectively reduced, and therefore the consistency of the device performance and the reliability and yield of the device can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of semiconductors, in particular to a transducer component, a MEMS piezoelectric micro-speaker and electronic equipment. Background Art

[0002] Piezoelectric MEMS speakers are small in size, thin in thickness, and can be mass-produced. The device uses MEMS technology, which has good performance consistency, low power consumption, and is easy to integrate and intelligent. In order to make MEMS speakers more widely used like MEMS microphones, the industry is committed to designing small-sized, high-performance MEMS speakers.

[0003] Devices based on silicon substrates and piezoelectric thin film materials often have difficulty in balancing the requirements of small size and high performance. The membrane structure of the diaphragm usually includes a supporting layer, the manufacturing process is complex and the material has high rigidity, which limits the polarization displacement of the diaphragm under piezoelectric drive, resulting in limited output sound pressure level. Utility Model Content

[0004] In view of this, the purpose of the present invention is to provide a transducer component, a MEMS piezoelectric micro-speaker and an electronic device.

[0005] In a first aspect, an embodiment of the utility model provides a transducer component, the transducer component comprising:

[0006] The diaphragm unit comprises at least two passivation layers stacked in layers;

[0007] The piezoelectric composite unit is arranged between two adjacent passivation layers in the diaphragm unit.

[0008] In combination with the first aspect, there is at least one piezoelectric composite unit, which is arranged in the middle area and / or the edge area inside the diaphragm unit.

[0009] In combination with the first aspect, there are multiple piezoelectric composite units, including a first piezoelectric composite unit, a second piezoelectric composite unit spaced apart from the first piezoelectric composite unit in a horizontal direction, and / or a third piezoelectric composite unit stacked with the first piezoelectric composite unit in a height direction.

[0010] In combination with the first aspect, the piezoelectric composite unit is a single piezoelectric layer structure or a double piezoelectric layer structure or a multi-electrode layer structure.

[0011] In combination with the first aspect, a diaphragm unit having a spring structure is obtained by opening slots on the diaphragm unit.

[0012] In combination with the first aspect, it also includes a flexible dry film that covers and / or fills the slotted gaps on the diaphragm unit.

[0013] In a second aspect, the present application provides a MEMS piezoelectric micro-speaker, which comprises: a silicon substrate and the above-mentioned transducer component, wherein the silicon substrate has a cavity.

[0014] In combination with the second aspect, there are at least two transducer assemblies, and the at least two transducer assemblies are stacked in a height direction, and two adjacent transducer assemblies are connected by a connecting member.

[0015] In conjunction with the second aspect, the connecting piece includes:

[0016] A frame, used to connect the edges of two adjacent transducer components;

[0017] The flexible connector is used to connect the central areas of two adjacent transducer assemblies so as to flexibly connect the two adjacent transducer assemblies.

[0018] In a third aspect, the present application provides an electronic device, which includes the above-mentioned MEMS piezoelectric micro-speaker.

[0019] The embodiment of the utility model brings the following beneficial effects: the transducer assembly, MEMS piezoelectric micro-speaker and electronic device provided by the present application, the diaphragm unit in the transducer assembly includes two passivation layers, which reduces the support layer compared to the diaphragm including the support layer structure in the prior art, simplifies the preparation process and production cost, and reduces the rigidity of the diaphragm unit, so that the diaphragm unit can produce a larger displacement when driven by piezoelectricity, thereby outputting a larger sound pressure level. In addition, the transducer assembly is a sandwich structure composed of a diaphragm unit and a piezoelectric composite unit, which can effectively reduce the residual stress in the MEMS process, thereby improving the consistency of device performance, as well as the reliability and yield of the device. Furthermore, in the MEMS piezoelectric speaker composed of two or more mutually spaced and stacked cascade transducer assemblies, compared with the piezoelectric speaker composed of a single MEMS transducer diaphragm, the amount of air pushed under the same excitation will be larger without increasing the speaker packaging area, which can further improve the sound pressure level SPL output of the device, thereby reducing the area of ​​the piezoelectric speaker, and meeting the requirements of miniaturization.

[0020] Other features and advantages of the utility model will be described in the following description, and partly become apparent from the description, or understood by practicing the utility model. The purpose and other advantages of the utility model are realized and obtained by the structures specifically pointed out in the description, claims and drawings.

[0021] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are some implementation methods of the utility model. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 A schematic diagram of the structure of a MEMS piezoelectric micro-speaker provided in Example 1 of the utility model;

[0024] Figure 2 A schematic diagram of the structure of a MEMS piezoelectric micro-speaker provided in Example 2 of the utility model;

[0025] Figure 3 A schematic diagram of the structure of a MEMS piezoelectric micro-speaker provided in Example 3 of the utility model;

[0026] Figure 4 A schematic diagram of the structure of a MEMS piezoelectric micro-speaker provided in Example 4 of the utility model;

[0027] Figure 5 A schematic structural diagram of a MEMS piezoelectric micro-speaker provided in Example 5 of the utility model;

[0028] Figure 6 A schematic diagram of the structure of another MEMS piezoelectric micro-speaker provided in Example 5 of the utility model;

[0029] Figure 7 A half-section schematic diagram of a MEMS piezoelectric micro-speaker with a single transducer component;

[0030] Figure 8 For Figure 7 Corresponding simulation effect diagram;

[0031] Fig. 9 For Figure 1 A half-section schematic diagram of the corresponding MEMS piezoelectric microspeaker;

[0032] Fig.10 For Fig. 9 Corresponding simulation effect diagram;

[0033] Fig.11 A schematic diagram of the structure of a MEMS piezoelectric micro-speaker provided in Example 7 of the utility model;

[0034] Fig.12 A schematic diagram of the structure of a MEMS piezoelectric micro-speaker D08 provided in Example 7 of the present utility model;

[0035] Fig.13A schematic diagram of the structure of a MEMS piezoelectric micro-speaker D09 provided in Example 7 of the present utility model;

[0036] Fig.14 A schematic diagram of the structure of a MEMS piezoelectric micro-speaker D10 provided in Example 7 of the present utility model;

[0037] Fig.15 This is a structural schematic diagram of the MEMS piezoelectric micro-speaker D11 provided in Example 7 of the utility model. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the utility model clearer, the technical solution of the utility model will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the utility model.

[0039] To facilitate understanding of this embodiment, the application scenarios and design concepts of the embodiments of the present application are briefly introduced below.

[0040] MEMS piezoelectric devices often have difficulty in achieving both small size and high performance. The diaphragm usually includes a supporting layer, and the manufacturing process is complex and the material has high rigidity, which limits the displacement of the diaphragm under piezoelectric drive, resulting in limited sound pressure level output by the MEMS piezoelectric micro-speaker.

[0041] Based on this, the embodiments of the present application provide a transducer component, a MEMS piezoelectric micro-generator and an electronic device.

[0042] Example 1

[0043] The present application provides a transducer component, combined with Figure 1 As shown, in the present application, the transducer assembly includes: a diaphragm unit and a piezoelectric composite unit.

[0044] The diaphragm unit includes at least two passivation layers stacked together.

[0045] The piezoelectric composite unit is arranged between two adjacent passivation layers in the diaphragm unit.

[0046] The diaphragm unit in the transducer assembly provided by the present application includes two passivation layers, which reduces the support layer compared to the diaphragm including the support layer structure in the prior art, simplifies the preparation process and production cost, and reduces the stiffness of the diaphragm unit, so that the diaphragm unit can produce a larger displacement when driven by piezoelectric, thereby outputting a larger sound pressure level. In addition, the transducer assembly is a sandwich structure composed of a diaphragm unit and a piezoelectric composite unit, which can effectively reduce the residual stress in the MEMS process, thereby improving the consistency of device performance, as well as the reliability and yield of the device.

[0047] In combination with the first aspect, there is at least one piezoelectric composite unit, which is arranged in the middle area and / or the edge area inside the diaphragm unit.

[0048] As an implementable manner, the cross-sectional size of the piezoelectric composite unit may be the same as the cross-sectional size of the diaphragm unit. In this case, the piezoelectric composite unit is disposed between two passivation layers with flush edges.

[0049] As another practicable manner, the cross-sectional size of the piezoelectric composite unit is smaller than the cross-sectional size of the diaphragm unit, and the relative positions of the piezoelectric composite unit and the diaphragm unit can be set arbitrarily, for example, set at the inner middle position, inner edge position, etc. of the piezoelectric composite unit. The specific setting position can be adjusted according to actual use conditions and is not limited here.

[0050] In combination with the first aspect, there are multiple piezoelectric composite units, including a first piezoelectric composite unit, a second piezoelectric composite unit spaced apart from the first piezoelectric composite unit in a horizontal direction, and / or a third piezoelectric composite unit stacked with the first piezoelectric composite unit in a height direction.

[0051] It is understandable that the number of the piezoelectric composite units can also be two or more, and the arrangement can be stacked, parallel, adjacent, staggered, etc. The specific arrangement and location can be adjusted according to actual use and are not limited here.

[0052] In combination with the first aspect, the piezoelectric composite unit is a single piezoelectric layer structure or a double piezoelectric layer structure or a multi-electrode layer structure.

[0053] When the piezoelectric composite layer unit is a single piezoelectric layer structure, the piezoelectric composite layer unit is composed of two electrode layers and a piezoelectric layer arranged between the two electrode layers.

[0054] When the piezoelectric composite layer unit is a double piezoelectric layer structure, the piezoelectric composite layer unit is composed of three electrode layers and a piezoelectric layer arranged between two adjacent electrode layers.

[0055] When the piezoelectric composite layer unit is a multi-piezoelectric layer structure, the piezoelectric composite layer unit is composed of N electrode layers and a piezoelectric layer arranged between two adjacent electrode layers.

[0056] The above three structures can be selected as needed in practical applications and are not limited here.

[0057] The material of the piezoelectric layer can be single crystal piezoelectric material or polycrystalline piezoelectric material, such as single crystal ALN, doped ALN, single crystal PZT, doped PZT, ZnO, barium titanate, lead titanate and other piezoelectric materials. The thickness of the piezoelectric layer is generally 0.2-5um, and the thickness of each piezoelectric layer can be different, which can be selected according to the actual situation.

[0058] The material of the electrode layer can be single crystal piezoelectric material, polycrystalline piezoelectric material, Mo, Pt, Al, Cu, LNO and other metal or non-metallic conductive films, single crystal metal material or alloy material, etc. The thickness of the electrode layer is generally 0.05-3um, and the thickness of each electrode layer can be different, which can be selected according to the actual situation.

[0059] The thickness of the transducer diaphragm is generally 0.5-50 um, preferably 1-5 um, and can be selected according to actual use requirements, design dimensions, and performance parameters, and is not limited here.

[0060] In combination with the first aspect, a diaphragm unit having a spring structure is obtained by opening slots on the diaphragm unit.

[0061] In this way, when the device is subjected to mechanical collision or accidentally dropped, the spring structure will buffer part of the impact force, thereby improving the reliability of the energy conversion component.

[0062] In combination with the first aspect, it also includes a flexible dry film that covers and / or fills the slotted gaps on the diaphragm unit.

[0063] A lightweight flexible dry film is used to cover and / or fill the slotted gaps on the diaphragm unit. Compared with an integral diaphragm unit without slots, the mass and stiffness of the diaphragm unit are reduced. Therefore, a larger excursion displacement can be obtained under the same piezoelectric effect, thereby outputting a larger sound pressure level.

[0064] In a second aspect, an embodiment of the present application further provides a MEMS piezoelectric micro-speaker, which comprises: a silicon substrate and the above-mentioned transducer component, wherein the silicon substrate has a cavity.

[0065] The edge of the transducer component is anchored to the edge of the silicon substrate.

[0066] In this embodiment, since the diaphragm unit of the transducer assembly is composed of two passivation layers, the support layer is removed to reduce the stiffness and mass, and the piezoelectric composite unit is arranged between the two passivation layers of the diaphragm unit. Under the same piezoelectric effect, the diaphragm unit with lighter mass and smaller stiffness will obtain a larger displacement, thereby outputting a larger sound pressure level. In addition, the use of silicon substrates instead of SOI substrates can reduce material costs. At the same time, since the diaphragm unit of the transducer assembly is composed of two passivation layers and the support layer is removed, the process flow and preparation steps can be reduced in the process of preparing the device. In addition, the transducer assembly is a sandwich structure composed of a laminated structure of a diaphragm unit and a piezoelectric composite unit, which is symmetrical along the central axis. The thermal expansion coefficients of the various membrane materials in the MEMS device are inconsistent. During the manufacturing process of the MEMS device, due to the temperature change in the MEMS process, it is easy to cause residual stress in the MEMS device. This stress may cause the device diaphragm to bulge or dent, and some may cause the diaphragm to wrinkle. In severe cases, problems such as film breakage may occur. In addition to affecting the performance of the MEMS device after manufacturing, the residual stress may also affect the reliability and yield of the device. This sandwich-type laminated film structure is an effective method to reduce residual stress during MEMS processing.

[0067] In combination with the second aspect, there are at least two transducer assemblies, and the at least two transducer assemblies are stacked in a height direction, and two adjacent transducer assemblies are connected by a connecting member.

[0068] In this way, by stacking two or more transducer components, a larger displacement can be obtained under the same cross-sectional size and the same piezoelectric effect, thereby outputting a higher sound pressure level, which is conducive to the miniaturization of the device.

[0069] In combination with the second aspect, the connecting member includes: a frame and a flexible connecting member.

[0070] The frame is used to connect the edges of two adjacent transducer components.

[0071] The flexible connector is used to connect the central areas of two adjacent transducer assemblies so as to flexibly connect the two adjacent transducer assemblies.

[0072] A flexible connector is used to connect one transducer component to another transducer component at their middle positions, and the left and right ends are connected to the frame and anchored on the substrate, avoiding suspension between two adjacent transducer components, which can improve the stability of the device during operation. The spring structure can buffer the impact when the device is subjected to external mechanical shock, falling, etc., thereby enhancing the mechanical reliability of the device.

[0073] Combination Figure 1As shown, the MEMS piezoelectric micro-speaker (denoted as D01) provided in the embodiment of the present application has a cavity 10a on the substrate 01, and two transducer components are arranged on the substrate 01, and the first transducer component 50b and the second transducer component 50a are stacked in sequence from top to bottom along the height direction. The second transducer component 50a is arranged on the substrate 01 and its edge is anchored to the edge of the substrate 01. The first transducer component 50b and the second transducer component 50a are connected by connecting members (30a, 30b, 30c).

[0074] The diaphragm unit and the piezoelectric composite unit in the first transducer component 50 b have the same cross-sectional dimensions. The number of the piezoelectric composite unit is one and it is a single piezoelectric layer structure. Specifically, the piezoelectric composite unit includes a top electrode layer 06 , a piezoelectric layer 05 and a bottom electrode layer 04 .

[0075] The two ends of the second transducer component 50a are anchored on the substrate 01. The diaphragm unit 50a in the second transducer component includes a first passivation layer 03 and a second passivation layer 02. A piezoelectric composite unit is arranged in the diaphragm unit to electrically insulate and isolate each piezoelectric composite unit. Slots (40a, 40b, 40c, 40d) are formed on the diaphragm unit. The width of the slots is between 0.5um and 2000um. The spring structure (combined with the slots) is obtained by forming the slots (40a, 40b, 40c, 40d). Figure 1 08, 09), whose ends 07, 10 are anchored on the substrate 01.

[0076] The first transducer assembly 50b is connected to the edge of the second transducer assembly 50a through the frame 30a, 30c, and the first transducer assembly 50b is connected to the central area of ​​the second transducer assembly 50a through the flexible connector 30b, so as to flexibly connect the two adjacent transducer assemblies. After the device D01 is structurally decoupled to release the process internal stress of each membrane layer, after applying the driving voltage, each diaphragm unit and the piezoelectric composite unit drive the diaphragm unit to produce a longitudinal offset displacement through power conversion. Under the connection of the connector (30a, 30b, 30c), the diaphragm unit in the first transducer assembly 50b and the diaphragm unit in the second transducer assembly 50a are offset together. Since the mass and stiffness of each diaphragm unit after the support layer is removed are reduced, under the same piezoelectric driving action, the offset displacement of each diaphragm unit increases, thereby increasing the output sound pressure level. In addition, under the same size structure, based on the above-mentioned stacked structure, a larger output sound pressure level can be obtained.

[0077] Among them, the frames 30a, 30c and the flexible connector 30b are all made of flexible materials, and the flexible material can also be used as a flexible dry film to fill or cover the slotted gaps 40a, 40b, 40c, and 40d. When used for covering, its width should be the same as the width of the slotted gaps 40a, 40b, 40c, and 40d.

[0078] Combination Figure 1 As shown, the cavity 10a is formed by deep silicon etching on the substrate 01, and the space between the first transducer component 50b and the second transducer component 50a is divided by the flexible connector 30b to obtain the second cavity 10b and the third cavity 10c. At this time, due to the slots 40a and 40b on the diaphragm unit in the second transducer component 50a, the second cavity 10b can be connected with the first cavity 10a; the diaphragm unit in the second transducer component 50a also has slots 40c and 40d to connect the third cavity 10c with the first cavity 10a. When designing, the second cavity 10b and the third cavity 10c can be designed as two independent cavities, or the two cavities can be connected to form a cavity structure.

[0079] It can be understood that when the diaphragm unit in the second transducer component 50a in the transducer component located at the bottom does not have slotted gaps 40a, 40b, 40c, 40d, or when the slotted gaps 40a, 40b, 40c, 40d are filled and / or covered with flexible materials, the first cavity 10a can be completely isolated from the second cavity 10b and the third cavity 10c.

[0080] The frames 30a, 30c and the flexible connector 30b are made of a flowable and curable polymer flexible material, and the slotted gaps 40a, 40b, 40c, and 40d are covered and filled with the flexible material, and a covering flexible film is formed after curing. When used as a speaker to vibrate and make sounds, the slotted gaps 40a, 40b, 40c, and 40d are covered and filled with the flexible material to prevent sound leakage, and the gas will not flow out of the slotted gaps 40a, 40b, 40c, and 40d, thereby improving the output sound pressure level of the MEMS sounder in the low frequency band. The use of flexible materials can increase the damping of the speaker system to reduce its resonance Q value, thereby reducing the total harmonic interference THD.

[0081] At the same time, when the diaphragm unit 50a is divided into a plurality of unconnected cantilever structures, the various parts can be connected by the flexible materials 30a, 30b, and 30c to form a vibrating whole, and the postures of the various parts remain consistent after processing. Under piezoelectric drive, they move up and down together as a whole; the slotted gaps 40a, 40b, 40c, and 40d are partially covered and filled with flexible materials, and the diaphragm unit 50a is a combination of rigidity and flexibility, which reduces the mass of the vibrating film 50a and is easy to produce a larger amplitude of vibration, thereby obtaining a larger displacement. When the driving piezoelectric force is equal, the lower the mass, the higher the acceleration of the diaphragm unit 50ad, so that a high sound pressure level SPL can be achieved at a high frequency.

[0082] The opposite surfaces of the two transducer components are connected to each other through an intermediate spring. When a drive is applied to move the whole upward or downward, the positions of the two are relatively fixed during movement. Compared with a speaker with a single transducer vibration component, the dual diaphragm structure pushes a larger amount of air and obtains a higher sound pressure level SPL.

[0083] Among them, the flexible material can also be used as an insulating layer and a dielectric layer to prevent electrical crosstalk between different layers in the chip, and can also be used as a protective layer to protect the chip surface from damage. The selection of the flexible material needs to meet the following conditions:

[0084] 1) Compatible with MEMS technology, and can perform vacuum lamination, exposure, etching and other processes.

[0085] 2) Reliability issues, dustproof, waterproof and insulating, while meeting the requirements of rigid material plates being fitted together, and no film tearing, delamination, or peeling will occur under different humidity conditions, force or excitation. With good dielectric properties, PI has excellent electrical insulation under high voltage and different frequencies, and can effectively prevent current leakage and electrical breakdown.

[0086] 3) Flexible materials can withstand high temperatures, maintain their physical properties at extreme temperatures (between -269°C and +400°C), and have a very low coefficient of thermal expansion: about 20 to 50ppm / °C. They can withstand the temperature of the SMD packaging process without causing reliability problems in the device, such as cracking of rigid materials.

[0087] 4) Excellent mechanical properties: high strength, high toughness, strong impact resistance, a certain elongation rate, and the flexible material will not be damaged when the device is deflected.

[0088] Based on the above principles, the flexible material may be selected from but not limited to one of the following materials: PI, FlexfinerSA, polyurethane, Parylene C, PVI-3, or other organic films, and the thickness of the flexible material is between 1 μm and 50 μm.

[0089] In the utility model, at least one piezoelectric composite unit of the MEMS piezoelectric micro-speaker can generate sound waves. By applying an electrical signal to the piezoelectric composite unit, the piezoelectric composite unit in the second transducer component 50a and the first transducer component 50b and the diaphragm unit perform electroacoustic conversion, and the diaphragm unit vibrates in the longitudinal direction to form sound waves, thereby realizing the conversion of mechanical acoustic energy.

[0090] It should be noted that when the voltage applied to the piezoelectric composite unit causes the diaphragm unit to perform electroacoustic conversion, the vibration directions of the diaphragm units in the second transducer component 50a and the first transducer component 50b are consistent, that is, they vibrate and deflect upward or up and down at the same time; if the vibration directions of the diaphragm units in the second transducer component 50a and the first transducer component 50b are opposite, compression or stretching in opposite directions will occur.

[0091] Among them, the audio driving signal applied to the second transducer component 50a and the first transducer component 50b corresponds to the output sound wave signal. The audio driving signal is generally a sinusoidal signal of DC voltage plus AC voltage, such as DC 10V+AC10VP, or driven by a bipolar signal.

[0092] It can be understood that the upper surface of the substrate 01 is parallel to the at least two stacked transducer components, and the substrate 01 material can also be silicon on insulator (SOI), glass, sapphire, quartz, etc. In this embodiment, the substrate 01 is a silicon substrate, which is low in cost and easy to purchase. The passivation layers 02 and 03 can be made of PI, silicon dioxide, aluminum nitride, etc., and the frame can be a hard substrate or a flexible substrate, usually single crystal silicon, polycrystalline silicon, glass, polymer, PI, PIV-3, SU8, PDMS, Parylene C or one or more combinations of organic compounds and inorganic compounds, for electrical isolation and protection.

[0093] Example 2

[0094] Combination Figure 2 As shown, the MEMS piezoelectric micro-speaker (denoted as D02) provided in the embodiment of the present application has a cavity 10a, and two transducer components are arranged on the substrate, and the first transducer component 50c and the second transducer component are stacked in sequence from top to bottom along the height direction. The second transducer component is arranged on the substrate 01 and its edge is anchored to the edge of the substrate. The first transducer component and the second transducer component are connected by connecting members (30a, 30b, 30c, 30d).

[0095] The diaphragm unit 50c and the piezoelectric composite unit in the first transducer assembly have the same cross-sectional dimensions, and the number of the piezoelectric composite unit is one and is a single piezoelectric layer structure.

[0096] The two ends of the second transducer assembly are anchored on the substrate. The second transducer assembly includes a first sub-transducer assembly 50a and a second sub-transducer assembly 50b. The end of the first sub-transducer assembly 50a close to the central axis of the substrate is connected to the first transducer assembly 50c through a flexible connector 30b, and the edge end is connected to the first transducer assembly 50c through a frame 30a; the end of the second sub-transducer assembly 50b close to the central axis of the substrate is connected to the first transducer assembly 50c through a flexible connector 30c, and the edge end is connected to the first transducer assembly 50c through a frame 30d. Among them, the flexible connectors 30b and 30c can be springs. The flexible connectors 30b, 30c and the frames 30a and 30b are made of flexible materials with elasticity. In this embodiment, the flexible connectors 30b, 30c and the frames 30a and 30b are specifically flexible dry films. The first transducer assembly 50c and the second transducer assembly are stacked and electrically connected in stages through the connectors (30a, 30b, 30c, 30d).

[0097] In this embodiment, the diaphragm units in the first sub-transducer assembly 50a and the second sub-transducer assembly 50b are both cantilever beam structures, which can reduce the stiffness of the second transducer diaphragm assembly and buffer the impact force when impacted by external force, thereby improving the structural stability of the device.

[0098] Without increasing the effective diaphragm unit sound area of ​​the MEMS piezoelectric speaker, since each diaphragm unit has no supporting layer structure, the stiffness of the diaphragm unit is reduced under the same device size. Under the same driving voltage, the deflection displacement of the diaphragm unit becomes larger, and compared with a speaker system composed of a single second transducer component, this structure can make the displacement stroke of the second transducer component larger, and the amount of air pushed will be larger, further improving the sound pressure level. Reducing the mass of the diaphragm unit of the vibration system is conducive to improving the sound pressure level curve and improving the mid-frequency performance of the speaker.

[0099] Example 3

[0100] Combination Figure 3 As shown, the present application provides a MEMS piezoelectric micro-speaker (denoted as D03 ). Compared with the MEMS piezoelectric micro-speaker (denoted as D02 ) provided in Example 2, the positions of the two transducer components of the MEMS piezoelectric micro-speaker (denoted as D03 ) are swapped.

[0101] In this embodiment, the cavity 10a of the substrate is completely isolated, and the first transducer component and the second transducer component 50a are arranged in sequence from top to bottom. The first transducer component includes a first sub-transducer component 50b and a second sub-transducer component 50c. The first sub-transducer component 50b, the first sub-transducer component 50b, the second transducer component 50a, the frame 30a and the flexible connector 30b together form a first cavity 10b; the second transducer component 50a, the second sub-transducer component 50c, the frame 30d and the flexible connector 30c together form a second cavity 10c.

[0102] After audio signals of opposite polarities are applied to the piezoelectric composite unit in the second transducer component 50a and the piezoelectric composite units in the first sub-transducer component 50b and the second sub-transducer component 50c, respectively, at a first moment the piezoelectric composite unit in the second transducer component 50a contracts so that the opposite ends are bent and deformed upward, and the piezoelectric composite units in the first sub-transducer component 50b and the second sub-transducer component 50c expand so that the opposite ends are bent and deformed downward.

[0103] At another moment, the piezoelectric composite unit in the second transducer assembly 50a expands so that the two opposite ends are bent and deformed downward, and the piezoelectric composite units in the first sub-transducer assembly 50b and the second sub-transducer assembly 50c contract so that the two opposite ends are bent and deformed upward. Thus, the diaphragm unit in the second transducer assembly 50a and the piezoelectric composite units in the first sub-transducer assembly 50b and the second sub-transducer assembly 50c move in opposite directions respectively, thereby realizing double-sided vibration, and the vibrations in opposite directions caused by the movement of the second transducer assembly 50a and the first transducer assembly can partially offset each other, reducing the vibration of the piezoelectric transducer D03 and improving the stability of the device. In addition, the device D03 uses multiple flexible connectors (30b, 30c) and frames (30a, 30d) to connect the ends of the diaphragm units in the first sub-transducer component 50b and the second sub-transducer component 50c to the first transducer component 50a, thereby avoiding one end of the diaphragm being suspended in the air, thereby improving the stability of the device D03, and in the event of mechanical shock or the device falling, the flexible connectors 30b and 30c formed by the spring structure can buffer the impact, thereby reducing the risk of mechanical reliability.

[0104] Compared with a speaker system consisting of a single second transducer assembly 50a, this structure can make the displacement stroke of the second transducer assembly 50a larger, push a larger amount of air, and further improve the sound pressure level. The vibration mass of the vibration system is reduced, which is conducive to improving the sound pressure level curve and improving the mid-frequency performance of the speaker.

[0105] Example 4

[0106] Combination Figure 4A MEMS piezoelectric micro-speaker (denoted as D04) has a first transducer component 50b and a second transducer component 50a on the MEMS piezoelectric micro-speaker (denoted as D04), and the first transducer component 50b and the second transducer component 50a are connected by a frame 30a, 30d and flexible connectors 30b, 30c.

[0107] In this embodiment, the position distribution of the diaphragm units in the first transducer assembly 50b and the second transducer assembly 50a is completely consistent, and the slotted gaps are covered by elastic structures 30b and 30c made of flexible dry film materials, which can reduce the rigidity of the diaphragm unit and prevent gas leakage when the diaphragm unit vibrates. Compared with the case where the first transducer assembly 50b and the second transducer assembly 50a are not connected, the displacement of the two opposite ends of the first transducer assembly 50b and the second transducer assembly 50a is increased, thereby increasing the vibration stroke and further improving the sound pressure level.

[0108] The diaphragm unit in the second transducer assembly 50a is etched into a slot structure and covered with a flexible dry film material (i.e., 30b, 30c), which can reduce the rigidity of the diaphragm unit while sealing the slot gap to prevent air pressure leakage. In addition, the flexible material replaces the rigid material to reduce the mass of the vibration unit, which is beneficial to improve the sound pressure level curve and improve the mid-frequency performance. The spring structure (i.e., 30b, 30c) between the first transducer assembly 50b and the second transducer assembly 50a can increase the damping of the speaker system to reduce its resonance Q value and reduce the total harmonic interference THD.

[0109] Example 5

[0110] The MEMS piezoelectric micro-speaker provided in the present application includes a plurality of transducer components stacked in a height direction, such as Figure 5 , Figure 6 shown.

[0111] Combination Figure 5 Compared with the device D01 in Example 1, the MEMS piezoelectric micro-speaker D05 shown in the figure has multiple transducer components, and two adjacent transducer components are connected by connecting members (such as 30a, 30b, 30c, 30d, 30e, 30f, 30g). Among them, the diaphragm unit of the transducer component 50c located in the middle has a slotted gap, and the transducer component located at the bottom includes a first sub-transducer component 50a and a second sub-transducer component 50b.

[0112] Combination Figure 6Compared with device D05, another MEMS piezoelectric micro-speaker (denoted as D06) shown in the figure has a groove in the middle of the transducer component in the middle of the device D06, so that the top transducer component 50d, flexible connectors 30f, 30b, 30c, 30g and the first sub-transducer component 50b and the second sub-transducer component 50c together form a larger cavity 10e.

[0113] It is understandable that the number of transducer components is not limited to that shown in the figure, but can also be 4, 5 or more, and two adjacent transducer components can be stacked and connected by a connector, which will not be elaborated here.

[0114] According to the MEMS piezoelectric micro-speaker of the utility model implementation mode, its mechanical resonance point can be designed to be within the audible sound range of 20Hz-20kHz. When the first-order resonance frequency of the sound generator is 2-5KHz, under certain driving conditions, the diaphragm unit driving displacement is large, and the output sound pressure level of the MEMS sound generator in the low-frequency range is large, and it can be used in low-frequency sound generators.

[0115] It can be understood that the mechanical resonance point of the device can also be designed to be outside the audible sound. When the mechanical resonance point of the MEMS piezoelectric micro-speaker is greater than 20kHz, the first, third and other odd harmonics of the MEMS piezoelectric micro-speaker are outside the audible sound frequency range, the sounder has lower nonlinearity and THD, and can be used in high-frequency sounders.

[0116] The MEMS piezoelectric micro-speaker provided in the present application is used as a speaker or sound generator. In order to produce sound, the larger the effective radiation area of ​​the device, the higher the sound pressure generated. The greater the displacement of the radiation area of ​​the diaphragm unit, the higher the sound pressure generated. When a single MEMS transducer component has a limited output sound pressure level SPL under excitation, two or more transducer components spaced apart from each other and stacked in cascade can be used to form a piezoelectric MEMS speaker. Without increasing the sound-emitting area of ​​the speaker, the vibration stroke of the piezoelectric micro-speaker is further increased, and the sound pressure level output of the device is further improved, which can meet the requirements of miniaturization.

[0117] Example 6

[0118] In the actual preparation and application process, the piezoelectric MEMS micro speaker can be a bridge structure with reinforcement on the opposite sides; it can also be a circular, rectangular or polygonal structure with reinforcement on all sides.

[0119] The MEMS piezoelectric micro-speaker D01 provided in Example 1 of the present application is a square structure with a size of 3 mm×3 mm, a piezoelectric PZT single-layer thin film structure, a silicon substrate, and an excitation piezoelectric DC of 15 V.

[0120] The structural diagram of the MEMS piezoelectric micro speaker with a single transducer component is as follows Figure 7As shown, the simulation diagram of the MEMS piezoelectric micro speaker is as follows Figure 8 The maximum displacement of the diaphragm unit in a device with a single transducer component is 33.4um. The displacement of the diaphragm unit of the device is integrated, and the volume of air pushed is 0.066mm. 3 .

[0121] The structural diagram of the MEMS piezoelectric micro-speaker D01 with two transducer components is as follows Fig. 9 As shown, the simulation diagram of the MEMS piezoelectric micro speaker is as follows Fig.10 The maximum displacement of the diaphragm unit in the device D01 with two stacked transducer components is 38.4um. By integrating the displacement of the diaphragm unit of the device D01, the volume of air pushed by the diaphragm unit in the first transducer component of the device D01 is 0.0645mm. 3 The volume of air pushed by the diaphragm unit in the second transducer assembly of device D01 is 0.0797mm 3 , then the volume of air pushed by the entire device D01 is 0.144mm 3 .

[0122] Comparing the two, it is shown that the maximum displacement of a single diaphragm unit under the action of electric drive is similar between the device with a single transducer component and the device D01 with two transducer components. However, since the device D01 has two superimposed transducer components, the amount of air pushed by the piezoelectric MEMS microspeaker can be increased, that is, the emission sound pressure level of the device can be increased.

[0123] It can be seen from the above technical solution that the utility model discloses a MEMS piezoelectric micro speaker, which has the following beneficial effects:

[0124] 1) Without changing the size of the MEMS piezoelectric speaker, multiple diaphragm units that are spaced apart and stacked in cascade connection can push a larger amount of air when the diaphragm units are offset equally, further improving the sound pressure level and meeting the requirements for miniaturization of the MEMS piezoelectric speaker.

[0125] 2) Applying audio signals of opposite polarities to at least two transducer components causes the diaphragm units of the two or more transducer components to contract and expand respectively, move in different directions, push the air to form sound waves, and thus achieve double-sided sound generation.

[0126] 3) The diaphragm units of multiple transducer components in the MEMS piezoelectric micro-speaker can be spatially stacked and multi-layered through flexible films and springs. When subjected to mechanical shock, falling, etc., the impact can be buffered and the reliability of the device can be improved.

[0127] 4) The use of flexible dry film materials can reduce the mass of the diaphragm unit, which is beneficial to improving the sound pressure level curve and improving the mid-frequency performance. At the same time, it can increase the system damping to reduce its resonance Q value and reduce the total harmonic interference THD.

[0128] Example 7

[0129] Combination Fig.11 As shown, the MEMS micro-piezoelectric speaker (denoted as D07) provided in the embodiment of the present application includes a first transducer component 50b and a second transducer component 50a. The first transducer component 50b is arranged on the top of the substrate, and its edge is anchored to the substrate; the second transducer component 50a is arranged on the bottom of the substrate, and its edge is anchored to the substrate through the frame 30a, 30d. A slot is opened on the second transducer component 50a, and it is covered by the flexible dry film 30b, 30c. The substrate has a cavity 10a.

[0130] When the MEMS piezoelectric transducer D07 is used as a speaker, an audio signal is applied to the piezoelectric composite unit in the first transducer component 50b and the second transducer component 50a, and the piezoelectric layer deforms to drive the first transducer component 50b and the second transducer component 50a to vibrate up and down and move, thereby pushing the air to make sound, converting mechanical acoustic energy, and thus forming sound waves.

[0131] The elastic force of the diaphragm unit in the nth transducer assembly is Fn=kn×xn, wherein Kn is the stiffness coefficient of the nth transducer assembly, and xn is the tensile length of the diaphragm unit in the nth transducer assembly.

[0132] Since the displacement of the diaphragm units in each transducer assembly should be consistent when driven, that is, xn is consistent, and since the diaphragm unit in the second transducer assembly 50b is slotted and etched to obtain a spring structure, K1 and K2 should be different. Based on the above formula, it can be known that F1 and F2 are also different. When the two transducer assemblies are driven to move upward or downward respectively, the double diaphragm structure pushes a larger amount of air than the speaker with a single transducer assembly, and the sound pressure level SPL obtained is higher. When the displacement x1 of the first transducer assembly and the displacement x2 of the second transducer vibration assembly are not equal, the sound wave frequency will be distorted under the drive of the same frequency electrical signal. Therefore, the two transducer assemblies can be controlled separately by driving electrical signals with different phases and / or amplitudes, so that the output sound pressure level of the MEMS piezoelectric micro-speaker is maximized.

[0133] The first transducer component 50b and the second transducer component 50a are respectively connected to the substrate. When driving force is applied, the whole moves upward or downward, and the positions of the two are relatively fixed during movement. Compared with a speaker with a single transducer component, the dual transducer component pushes a larger amount of air and obtains a higher sound pressure level SPL.

[0134] In addition, covering the slotted gap with a flexible material can prevent sound leakage, and the gas will not flow out of the slotted gap, which improves the output sound pressure level of the MEMS sounder in the low frequency band; the slotted part is covered and filled with a flexible material, and the diaphragm unit is a combination of rigidity and flexibility, which reduces the moving mass of the vibrating film and is easy to produce a larger amplitude of vibration, thereby obtaining a larger displacement. When the force of the electrode is equal, the lower the mass, the higher the diaphragm acceleration, and a high sound pressure level SPL is achieved at high frequencies.

[0135] It can be understood that based on the technical concept of distributing the transducer components along the axial direction (ie, the height direction) of the substrate, the MEMS piezoelectric micro-speaker provided in the present application can also be Fig.12 (denoted as D08), Fig.13 (denoted as D09), Fig.14 (denoted as D10) and Fig.15 The structure shown in (denoted as D11) is not described in detail here. The MEMS piezoelectric micro-speaker constructed by changing the number of transducer components and the position of the slots and gaps of the specific diaphragm unit should be within the protection scope of this application and will not be described in detail here.

[0136] In a third aspect, the present application also provides an electronic device, which includes the MEMS piezoelectric micro-speaker as described above.

[0137] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system and device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0138] In addition, in the description of the embodiments of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0139] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0140] Finally, it should be noted that the above embodiments are only specific implementation methods of the utility model, which are used to illustrate the technical solution of the utility model, rather than to limit it. The protection scope of the utility model is not limited thereto. Although the utility model is described in detail with reference to the above embodiments, those skilled in the art should understand that any technician familiar with the technical field can still modify the technical solution recorded in the above embodiments within the technical scope disclosed by the utility model, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solution of the embodiment of the utility model, and should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model shall be based on the protection scope of the claims.

Claims

1. A transducer assembly, characterized in that: The energy conversion component comprises: The diaphragm unit comprises at least two passivation layers stacked in layers; The piezoelectric composite unit is arranged between two adjacent passivation layers in the diaphragm unit.

2. The transducer assembly according to claim 1, characterized in that: There is at least one piezoelectric composite unit, which is arranged in the middle area and / or the edge area inside the diaphragm unit.

3. The transducer assembly according to claim 1, characterized in that: There are multiple piezoelectric composite units, including a first piezoelectric composite unit, a second piezoelectric composite unit spaced apart from the first piezoelectric composite unit in a horizontal direction, and / or a third piezoelectric composite unit stacked with the first piezoelectric composite unit in a height direction.

4. The transducer assembly according to claim 1, characterized in that: The piezoelectric composite unit is a single piezoelectric layer structure, a double piezoelectric layer structure, or a multi-electrode layer structure.

5. The transducer assembly according to claim 1, characterized in that: The diaphragm unit is provided with slots and slits to obtain the diaphragm unit having a spring structure.

6. The transducer assembly according to claim 5, characterized in that: It also includes a flexible dry film that covers and / or fills the slotted gaps on the diaphragm unit.

7. A MEMS piezoelectric micro speaker, characterized in that: The MEMS piezoelectric micro-speaker comprises: a silicon substrate and a transducer assembly as claimed in any one of claims 1 to 6, wherein the silicon substrate has a cavity.

8. The MEMS piezoelectric microspeaker according to claim 7, characterized in that: There are at least two transducer assemblies, and at least two transducer assemblies are stacked in a height direction, and two adjacent transducer assemblies are connected via a connecting piece.

9. The MEMS piezoelectric microspeaker according to claim 8, characterized in that: The connecting piece comprises: A frame, used to connect the edges of two adjacent transducer components; The flexible connector is used to connect the central areas of two adjacent transducer assemblies so as to flexibly connect the two adjacent transducer assemblies.

10. An electronic device, characterized in that: The electronic device comprises the MEMS piezoelectric micro-speaker as described in any one of claims 7-9.

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