MEMS device, manufacturing method thereof and electronic equipment

Abstract

The invention provides an MEMS device, a manufacturing method thereof and electronic equipment, relates to the field of MEMS devices, and can reduce the resistance to a piezoelectric vibration unit by increasing the surface area of a vibrating diaphragm. The MEMS device comprises a substrate, a plurality of piezoelectric vibration units and a vibrating diaphragm. The substrate comprises a cavity and a frame structure surrounding the cavity, the plurality of piezoelectric vibration units are dispersedly arranged on the frame structure, the vibrating diaphragm adopts an organic thin film, and the vibrating diaphragm is arranged on the plurality of piezoelectric vibration units and covers the whole cavity. Wherein the part, located above the cavity, of the vibrating diaphragm is provided with at least one fluctuating part, so that the surface of the vibrating diaphragm can be increased, the resistance of the vibrating diaphragm to the piezoelectric vibration structure is reduced, and the piezoelectric vibration structure (cantilever beam) has a larger free vibration space.

Description

Technical Field

[0001] The present application relates to the field of MEMS devices, and in particular to a MEMS device and a manufacturing method thereof, and an electronic device. Background Art

[0002] MEMS (micro-electro-mechanical system) speakers are miniature transducers that convert electrical signals into acoustic signals. Their core components are manufactured on semiconductor materials using MEMS technology. Among them, piezoelectric MEMS speakers have a simple structure and do not require special materials such as soft magnetic materials, making the processing and integration technology simpler. Therefore, they have greater advantages in realizing lightweight and high-performance miniature speakers, and are widely used in mobile electronic products.

[0003] refer to Figure 1 As shown, when the existing piezoelectric MEMS speaker produces sound, an electric driving signal is applied to the piezoelectric vibration unit 1 to generate displacement, which drives the diaphragm 2 to vibrate together and produce sound. Since the diaphragm 2 is closely attached to the surface of the piezoelectric vibration unit 1, it will generate resistance to the piezoelectric vibration unit 1, which will affect the acoustic performance of the speaker. Summary of the invention

[0004] The present application provides a MEMS device and a manufacturing method thereof, and an electronic device, which can reduce the resistance to a piezoelectric vibration unit by increasing the surface area of ​​a diaphragm.

[0005] The present application provides a MEMS device, and the MEMS speaker includes a substrate, a plurality of piezoelectric vibration units and a diaphragm. The substrate includes a cavity and a frame structure surrounding the cavity, and a plurality of piezoelectric vibration units are dispersedly arranged on the frame structure. The diaphragm is made of an organic film, and the diaphragm is arranged on a plurality of piezoelectric vibration units and covers the entire cavity. Among them, the diaphragm has at least one undulating portion in the portion located above the cavity, so that the area of ​​the diaphragm can be increased at the undulating position. In this way, when the area of ​​the cavity remains unchanged, the area of ​​the diaphragm is increased, and the resistance of the diaphragm to the plurality of piezoelectric vibration structures can be reduced, so that the piezoelectric vibration structure (cantilever beam) has a larger free vibration space. In this way, the acoustic performance of the MEMS speaker, such as the sound pressure level and total harmonic distortion, can be improved.

[0006] In addition, by increasing the area of ​​the diaphragm, the stiffness of the diaphragm can be improved without affecting the stretchability of the diaphragm, thereby reducing the stress of the entire device during operation, extending the service life of the diaphragm, and improving the overall reliability of the device.

[0007] In some possible implementations, the undulating portion may be a convex portion that bends upward or a concave portion that bends downward. In this case, at least one undulating portion provided on the diaphragm may be a convex portion or a concave portion, or may include both convex portions and concave portions.

[0008] In some possible implementations, the diaphragm is provided with holes at the position of the undulating portion, and the hole diameter is between 0.5 μm and 5 μm. By setting the hole diameter to be less than or equal to 5 μm, it can be ensured that the diaphragm does not leak air at the hole during high-frequency vibration, thereby reducing the sound pressure level. By setting the hole diameter to be greater than or equal to 0.5 μm, it can be ensured that the sacrificial layer under the diaphragm can be better removed through the hole.

[0009] In some possible implementations, the extension direction of at least one undulating portion is consistent with the direction of the inner edges of multiple piezoelectric vibration units (i.e., the edges close to one side of the cavity), thereby reducing the concentrated stress on the diaphragm to a greater extent, that is, reducing the resistance of the diaphragm to the piezoelectric vibration structure to a greater extent.

[0010] In some possible implementations, the cross-section of the undulating portion is rectangular.

[0011] In some possible implementations, the cross-section of the undulating portion is trapezoidal.

[0012] In some possible implementations, a distribution pattern of the at least one undulating portion on the diaphragm is a symmetrical pattern.

[0013] In some possible implementations, the distribution pattern of the at least one undulating portion on the diaphragm is an asymmetric pattern.

[0014] In some possible implementations, the substrate includes a stacked silicon-based layer and a first dielectric layer; the first dielectric layer is located between the silicon-based layer and the plurality of piezoelectric vibration units; and the first dielectric layer includes SiO2.

[0015] In some possible implementations, the piezoelectric vibration unit includes: a vibration layer, a first electrode layer, a piezoelectric layer, and a second electrode layer stacked in sequence; wherein the vibration layer is closer to the substrate than the first electrode layer.

[0016] In some possible implementations, the substrate and the vibration layer are made of SOI.

[0017] The present application also provides a method for manufacturing a MEMS device, which may include: manufacturing a plurality of piezoelectric vibration units on a substrate; wherein the plurality of piezoelectric vibration units are arranged along the edge of the cavity to be formed area. Forming at least one undulating structure on the surface of the substrate in the cavity to be formed area. Forming a diaphragm on the surface of the piezoelectric vibration unit using an organic polymer material, and extending to cover the entire cavity to be formed area, so as to form an undulating portion at the position where the diaphragm covers the undulating structure. Etching is performed from the back side of the substrate, and a cavity is formed by penetrating the substrate in the cavity to be formed area.

[0018] In some possible implementations, the above-mentioned manufacturing of multiple piezoelectric vibration units on a substrate includes: providing SOI; wherein the SOI includes a first silicon-based layer, a first dielectric layer, and a second silicon-based layer. A first electrode layer, a piezoelectric layer, and a second electrode layer are sequentially manufactured on the second silicon-based layer, and the second electrode layer, the piezoelectric layer, the first electrode layer, and the second silicon-based layer are etched to form multiple piezoelectric vibration units, and the second silicon-based layer serves as a vibration layer in the piezoelectric vibration unit.

[0019] In some possible implementations, the forming of at least one undulating structure on the surface of the substrate in the area to be formed with the cavity may include: forming a convex structure as the undulating structure on the surface of the substrate in the area to be formed with the cavity. In this case, after forming a diaphragm on the surface of the piezoelectric vibration unit using an organic polymer material and extending to cover the entire area to be formed with the cavity, the manufacturing method may further include: forming a hole on the diaphragm and removing the convex structure through the hole.

[0020] In some possible implementations, the forming of at least one undulating structure on the surface of the substrate in the area where the cavity is to be formed may include: forming a convex structure as the undulating structure on the surface of the substrate in the area where the cavity is to be formed. In this case, etching from the back side of the substrate to form a cavity through the substrate in the area where the cavity is to be formed may include: etching from the back side of the substrate to form a hole through the substrate in the area where the cavity is to be formed, and removing the convex structure.

[0021] In some possible implementations, the forming of the undulating structure on the surface of the substrate in the area where the cavity is to be formed may include: etching the surface of the substrate in the area where the cavity is to be formed to form a recessed structure as the undulating structure.

[0022] The present application also provides an electronic device, which includes a controller and a MEMS device provided in any of the aforementioned possible implementation methods, the MEMS device is connected to the controller, and the controller is used to control multiple piezoelectric vibration units in the MEMS device to drive the diaphragm to vibrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the structure of a MEMS speaker provided in the prior art;

[0024] Figure 2 A schematic diagram of the structure of a MEMS speaker provided in an embodiment of the present application;

[0025] Figure 3 for Figure 2 Schematic diagram of the cross section along the A1-A2 position;

[0026] Figure 4 A schematic diagram of a frame structure in a MEMS speaker provided in an embodiment of the present application;

[0027] Figure 5 A schematic diagram of the structure of a MEMS speaker provided in an embodiment of the present application;

[0028] Figure 6 A schematic diagram of the structure of a MEMS speaker provided in an embodiment of the present application;

[0029] Figure 7 A schematic diagram of a planar structure of a MEMS speaker provided in an embodiment of the present application;

[0030] Figure 8 A schematic diagram of a planar structure of a MEMS speaker provided in an embodiment of the present application;

[0031] Fig. 9 A schematic diagram of a diaphragm structure in a MEMS speaker provided in an embodiment of the present application;

[0032] Fig.10 A schematic diagram of a diaphragm structure in a MEMS speaker provided in an embodiment of the present application;

[0033] Fig.11 A flowchart of a manufacturing method of a MEMS speaker provided in an embodiment of the present application;

[0034] Fig.12 A schematic diagram of a manufacturing process of a MEMS speaker provided in an embodiment of the present application;

[0035] Fig.13 A schematic diagram of a manufacturing process of a MEMS speaker provided in an embodiment of the present application;

[0036] Fig.14 A flowchart of a manufacturing method of a MEMS speaker provided in an embodiment of the present application;

[0037] Fig.15 A schematic diagram of a manufacturing process of a MEMS speaker provided in an embodiment of the present application;

[0038] Fig.16A flowchart of a manufacturing method of a MEMS speaker provided in an embodiment of the present application;

[0039] Fig.17 A schematic diagram of the manufacturing process of a MEMS speaker provided in an embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0041] The terms "first", "second", etc. in the specification embodiments, claims and drawings of the present application are only used for the purpose of distinguishing descriptions, and cannot be understood as indicating or implying relative importance, nor can they be understood as indicating or implying order. "And / or" is used to describe the association relationship of associated objects, indicating that three relationships may exist. For example, "A and / or B" can mean: only A exists, only B exists, and A and B exist at the same time, where A and B can be singular or plural. The character " / " generally indicates that the objects associated before and after are in an "or" relationship. "At least one (item)" means one or more, and "multiple" means two or more. "Installation", "connection", "connected", etc. should be understood in a broad sense, for example, it can be an electrical connection or a mechanical connection; it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or it can be indirect through an intermediate medium, or it can be the internal connection of two elements. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, including a series of steps or units. Methods, systems, products or devices are not necessarily limited to those steps or units explicitly listed, but may include other steps or units that are not explicitly listed or inherent to these processes, methods, products or devices. "Up", "down", "left", "right", etc. are only used relative to the orientation of the components in the drawings. These directional terms are relative concepts. They are used for description and clarification relative to the description, which may change accordingly according to the change of the orientation of the components in the drawings.

[0042] First, the professional terms involved in the embodiments of the present application are explained.

[0043] Sound pressure level (SPL) and total harmonic distortion (THD) are important indicators of the acoustic performance of a loudspeaker.

[0044] The sound pressure level (SPL) is defined as the ratio of the measured sound pressure p to the reference sound pressure p (ref), taken from the common logarithm and multiplied by 20, which directly reflects the sound-producing ability of the speaker.

[0045] Total harmonic distortion (THD) is an indicator of harmonic distortion of electrical signals. It is commonly defined as the ratio of the sum of the powers of all harmonic components to the power of the fundamental frequency signal. The lower the THD, the higher the fidelity of the speaker, and the closer its output audio signal is to the input signal.

[0046] An embodiment of the present application provides an electronic device, which may be a device having a MEMS device, such as a headset, a mobile phone, a tablet computer, a personal computer (PC), etc. The present application does not limit the configuration form of the electronic device.

[0047] The electronic device provided in the embodiment of the present application adopts a MEMS device of a new structure, and the MEMS device can be a MEMS speaker, and the following embodiments are all described by taking this as an example. The MEMS speaker increases the surface area of ​​the diaphragm by setting an undulating portion on the diaphragm, thereby reducing the resistance to the piezoelectric vibration structure, thereby improving the acoustic performance of the MEMS speaker.

[0048] It is understandable that MEMS speakers are made using micro-electromechanical systems (MEMS) technology. MEMS technology is based on semiconductor processing technologies such as graphics and etching, and naturally has the characteristics of high processing accuracy, good consistency, and mass production, which can be suitable for the miniaturization of MEMS speakers.

[0049] Of course, in addition to the aforementioned MEMS speakers, the above-mentioned electronic devices may also include other devices electrically connected to the MEMS speakers, such as controllers, memories, circuit boards, etc. This application does not impose any restrictions on this, and in practice it can be set according to the needs of the electronic device.

[0050] The specific structure of the novel MEMS speaker provided in the embodiment of the present application is described below.

[0051] Indicative, reference Figure 2 and Figure 3 ( Figure 2 As shown in the cross-sectional schematic diagram along the position A1-A2, an embodiment of the present application provides a MEMS speaker, which includes a substrate 10, a plurality of piezoelectric vibration units 20, and a diaphragm 30.

[0052] refer to Figure 4As shown, the substrate 10 includes a cavity 101 and a frame structure 102 surrounding the cavity 101. The frame structure 102 provides mechanical support for the MEMS speaker, and the cavity 101 can enhance the sound generated by the diaphragm 30.

[0053] refer to Figure 2 and Figure 3 As shown, a plurality of piezoelectric vibration units 20 are dispersedly arranged on the frame structure 102 , and the diaphragm 30 is arranged on the plurality of piezoelectric vibration units 20 and covers the entire cavity 101 .

[0054] Figure 2 The example of two piezoelectric vibration units 20 in the MEMS speaker is only used for illustration, but the present application is not limited thereto. In other possible implementations, more piezoelectric vibration units 20, such as 4 or 6, may be dispersed around the frame structure 102.

[0055] Indicative, such as Figure 3 As shown, the piezoelectric vibration unit 20 may include a vibration layer 201 and a piezoelectric vibration film 202. The vibration layer 201 extends from the surface of the frame structure 102 to one side of the cavity 101 and is suspended. The piezoelectric vibration film 202 is arranged on the vibration layer 201 (that is, the side away from the frame structure 102), but the piezoelectric vibration film 202 does not completely cover the end of the vibration layer 201 (that is, the area close to one side of the cavity 101). The piezoelectric vibration film 202 may include a lower electrode layer a1 (that is, a first electrode layer), a piezoelectric layer b, and an upper electrode layer a2 (that is, a second electrode layer) stacked from bottom to top.

[0056] In this case, the diaphragm 30 covers the upper surface of the piezoelectric diaphragm 202 and the upper surface of the exposed vibration layer 201, and covers the entire top area of ​​the cavity 101. The portion of the piezoelectric vibration unit 20 extending into the cavity 101 forms a cantilever beam. In this way, when the electronic device is working, an electrical signal can be applied to the piezoelectric layer b through the controller (or control circuit) to the lower electrode layer a1 and the upper electrode layer a2, and the piezoelectric layer b undergoes an inverse piezoelectric effect to produce a stretching deformation, and generates stress between the piezoelectric layer 201, thereby driving the diaphragm 30 to vibrate.

[0057] In the present application, the diaphragm 30 is made of an organic film, that is, the diaphragm 30 is mainly made of an organic polymer material, which has the advantages of light weight, good ductility, and tensile resistance.

[0058] As an illustration, in some possible implementations, the diaphragm 30 may be made of one or more organic polymer materials such as polyimide, polyethylene, polypropylene, polyethylene terephthalate, etc., and the present application does not impose any limitation on this.

[0059] Since the diaphragm 30 and the surface of the piezoelectric vibration unit 20 are in close contact, the diaphragm 30 will generate resistance to the piezoelectric vibration unit 20 during the vibration process driven by the piezoelectric vibration unit 20, which will further affect the acoustic performance of the MEMS speaker.

[0060] Based on this, Figure 3 As shown, the MEMS speaker provided in the embodiment of the present application adopts a diaphragm 30 of a new structure, and the diaphragm 30 has at least one undulating portion 301 in the portion located above the cavity 101, that is, the diaphragm 30 is not planar in the region located above the cavity 101, but at least part of the region is undulating, so that the area of ​​the diaphragm 30 can be increased at the undulating position. In this way, when the area of ​​the cavity 101 remains unchanged, increasing the area of ​​the diaphragm 30 can reduce the resistance of the diaphragm 30 to the piezoelectric vibration structure 20, thereby allowing the piezoelectric vibration structure 20 (cantilever beam) to have a larger free vibration space. In this way, acoustic performance such as sound pressure level (SPL) and total harmonic distortion (THD) can be improved.

[0061] In addition, in the present application, by increasing the area of ​​the diaphragm 30, the stiffness of the diaphragm 30 can be improved without affecting the stretchability of the diaphragm, thereby reducing the stress during the operation of the entire device, extending the service life of the diaphragm, and improving the overall reliability of the device.

[0062] The present application does not impose any limitation on the material and configuration of the substrate 10 and the vibration layer 201 .

[0063] Indicative, reference Figure 3 As shown, the substrate 10 may be a multi-layer structure. For example, in some possible implementations, the substrate 10 may include a stacked silicon-based layer 11 and a first dielectric layer 12, wherein the first dielectric layer 12 may be SiO2, but is not limited thereto.

[0064] Schematically, the vibration layer 201 may be based on silicon.

[0065] In some embodiments, the substrate 10 and the vibration layer 201 can be made of SOI (silicon on insulator) as a whole, which is silicon on an insulating substrate, and a SiO2 layer can be introduced between the substrate silicon and the top silicon. In this case, the substrate silicon can be used as the silicon base layer 11 in the substrate 10, the SiO2 layer can be used as the first dielectric layer 12 in the substrate 10, and the top silicon can be used as the vibration layer 201.

[0066] The relevant configuration of the undulating portion 301 is described in detail below.

[0067] The present application does not impose any limitation on the size, shape, number, etc. of the undulating parts 301 formed on the diaphragm 30 , and they can be set as needed in practice.

[0068] The present application does not limit the bending direction of the undulating portion 301 .

[0069] For example, Figure 3 As shown, in some possible implementations, the undulating portion 301 may be a convex portion that bends upward.

[0070] For example, Figure 5 As shown, in some possible implementations, the undulating portion 301 may also be a downwardly curved concave portion.

[0071] When a plurality of undulating portions 301 are provided on the diaphragm 30 , the plurality of undulating portions 301 may all be convex portions; the plurality of undulating portions 301 may also be uniformly concave portions; some of the plurality of undulating portions 301 may be convex portions and some may be concave portions.

[0072] Of course, the above-mentioned raised portion and recessed portion are only a relative concept. Schematically, the raised portion and recessed portion can refer to the reference plane of the diaphragm 30, the portion above the reference plane is the raised portion, and the portion below the reference plane is the recessed portion. The reference plane of the diaphragm 30 can be the plane where the upper surface of the substrate 10 is located.

[0073] Take the case where the undulating portion 301 is a convex portion as an example. Figure 6 and Fig.13 As shown, when the MEMS technology is used to make the protrusion (301), a protrusion structure 301a can be first made as a sacrificial layer, and then the diaphragm 30 is made on the protrusion structure 301a, so that the diaphragm 30 forms the protrusion (301) at the position covering the protrusion structure 301a. After the diaphragm 30 is made, the protrusion structure 301a needs to be removed.

[0074] Based on this, Figure 6 As shown, in some possible implementations, a hole 302 may be provided at the location of the diaphragm 30 at the undulating portion 301, so as to remove the protruding structure ( Figure 6 Not shown, please refer to Fig.13 ), please refer to the relevant production method section below for details.

[0075] The present application does not impose any limitation on the size, number, position distribution, etc. of the holes 302 , and they can be set as needed in practice.

[0076] Illustratively, in some possible implementations, the diameter of the hole 302 may be in the range of 0.5 μm to 5 μm.

[0077] Specifically, by setting the aperture of the hole 302 to be less than or equal to 5 μm, it is possible to ensure that the diaphragm 30 does not leak air at the hole 302 during high-frequency vibration, thereby reducing the sound pressure level (SPL). By setting the aperture of the hole 302 to be greater than or equal to 0.5 μm, it is possible to ensure that the sacrificial layer under the diaphragm 30 can be better removed through the hole 302.

[0078] It should be understood that in the MEMS speaker, the plurality of piezoelectric vibration units 20 are dispersedly arranged along a circumference of the frame structure 102, and the plurality of piezoelectric vibration units 20 are distributed on the frame structure 102 in a relatively arranged manner in groups of two piezoelectric vibration units 20. When the MEMS speaker is working, that is, when the diaphragm 30 vibrates, the stress concentration area on the diaphragm 30 is substantially consistent with the direction of the inner edge of the plurality of piezoelectric vibration units 20 (that is, the edge close to the side of the cavity 101).

[0079] Based on this, reference Figure 7 and Figure 8 As shown, in order to reduce the concentrated stress on the diaphragm 30 to a greater extent, that is, to reduce the resistance of the diaphragm 30 to the piezoelectric vibration structure 20 to a greater extent, the extension direction of the undulating portion 301 can be set to be consistent or approximately consistent with the direction of the inner edges of multiple piezoelectric vibration units 20, thereby greatly improving the acoustic performance of the MEMS speaker.

[0080] For example, in some possible implementations, Figure 7 As shown, the MEMS speaker is provided with two (a group of) oppositely arranged piezoelectric vibration units 20, and the inner edges of the two piezoelectric vibration units 20 are arranged in parallel in the opposite area; in this case, the undulating portion 301 formed on the diaphragm 30 may include a plurality of strip-shaped protrusions (or depressions) located between the two piezoelectric vibration units 20 and parallel (or approximately parallel) to the edge of the piezoelectric vibration unit 20. Of course, according to actual needs, the undulating portion 301 formed on the diaphragm 30 may also include a plurality of strip-shaped protrusions (or depressions) located on the side of the piezoelectric vibration unit 20 and parallel (or approximately parallel) to the side of the piezoelectric vibration unit 20.

[0081] For example, in some possible implementations, Figure 8As shown, the MEMS speaker is provided with six (three groups) relatively arranged piezoelectric vibration units 20, and the six piezoelectric vibration units 20 can be respectively arranged along the six sides of the hexagonal frame structure 102. In this case, the undulating portion 301 formed on the diaphragm 30 can include a plurality of concentric annular protrusions (or depressions) located in the inner area of ​​the six piezoelectric vibration units 20, and of course, it can also be set as a plurality of concentric hexagonal protrusions (or depressions). According to actual needs, the undulating portion 301 formed on the diaphragm 30 can also include a plurality of strip-shaped protrusions (or depressions) located between two adjacent piezoelectric vibration units 20 and approximately parallel to the side of the piezoelectric vibration unit 20.

[0082] In addition, since the multiple piezoelectric vibration units 20 are symmetrically arranged, the concentrated stress on the diaphragm 30 is also correspondingly distributed in a symmetrical form. Therefore, in some possible implementation methods, in order to uniformly reduce the concentrated stress on the diaphragm 30, the distribution pattern of the undulating portion 301 can be set to be consistent with or similar to the distribution area of ​​the concentrated stress. In this case, the distribution pattern of the undulating portion 301 formed on the diaphragm 30 is a symmetrical pattern.

[0083] Of course, since the diaphragm 30 (organic film) has its intrinsic vibration mode, resonance will occur at a specific sound frequency. In order to reduce the adverse sound effect of the resonance on the MEMS speaker, in some possible implementation methods, according to actual needs, the distribution pattern of the undulating portion 301 formed on the diaphragm 30 can be locally adjusted, and the distribution pattern of the undulating portion 301 can be set to an asymmetric pattern to change the stiffness distribution of the diaphragm 30, destroy the symmetry, thereby reducing resonance and improving total harmonic distortion (THD).

[0084] In addition, the cross-sectional shape of the undulating portion 301 can be determined according to actual needs and related manufacturing processes, and the present application does not impose any limitation on this.

[0085] For example, Fig. 9 As shown, in some possible implementations, the cross-section of the undulating portion 301 may be rectangular or approximately rectangular.

[0086] For example, Fig.10 As shown, in some possible implementations, the cross-section of the undulating portion 301 may be trapezoidal or approximately trapezoidal.

[0087] Of course, in some possible implementations, the undulating portions 301 of the diaphragm 30 at different positions may have cross-sections of different shapes.

[0088] The following further describes the MEMS speaker provided in the embodiment of the present application in combination with three different manufacturing methods.

[0089] Production method 1

[0090] The present application also provides a method Figure 6 The manufacturing method of the MEMS speaker is illustrated. The manufacturing method is described by taking the undulating part 301 as a convex part as an example.

[0091] like Fig.11 As shown, the production method may include:

[0092] Step 11. Reference Fig.12 As shown in (a), a plurality of piezoelectric vibration units 20 are manufactured on a substrate 10; wherein the plurality of piezoelectric vibration units 20 are dispersedly arranged along the edge of a cavity to-be-formed region 101a.

[0093] In some possible implementations, reference is made to Fig.12 As shown in (a), the above step 11 may include: providing SOI, wherein the SOI includes a first silicon-based layer (11) 11, a SiO2 layer (12), and a second silicon-based layer (201) stacked in layers; wherein the first dielectric layer 12 may be a SiO2 layer. Next, a first electrode layer a1, a piezoelectric layer b, and a second electrode layer a2 are sequentially fabricated on the SOI, and then the second electrode layer a2, the piezoelectric layer b, the first electrode layer a1, and the second silicon-based layer (201) are sequentially patterned by an etching process to form a plurality of piezoelectric vibration units 20. The first silicon-based layer (11) 11 and the SiO2 layer (12) in the SOI serve as the substrate 10, and the second silicon-based layer (201) serves as the vibration layer in the piezoelectric vibration unit 20.

[0094] The cavity to-be-formed region 101 a is used to form a cavity by etching the substrate in a subsequent manufacturing process, and details thereof may refer to the relevant contents below.

[0095] Step 12: Reference Fig.12 As shown in (b), a protruding structure 301a is formed on the surface of the substrate in the cavity to be formed area 101a.

[0096] In some possible implementations, reference is made to Fig.12 As shown in (b), the above step 12 may include: forming a protruding structure 301a on the surface of the SiO2 layer (12) located in the cavity to be formed area 101a, and the protruding structure 301a may also be called a protruding undulating structure.

[0097] The protruding structure 301 a as a sacrificial layer needs to be removed in the subsequent manufacturing process. Therefore, in the actual manufacturing process, the protruding structure 301 a can be made of a material that is easy to remove.

[0098] Step 13. Reference Fig.12As shown in (c), a diaphragm 30 is formed on the surface of the piezoelectric vibration unit 20 using an organic polymer material, and extends to cover the entire cavity to be formed area 101a, so as to form a protrusion (301) at the position where the diaphragm 30 covers the protrusion structure 301a.

[0099] In some possible implementations, reference is made to Fig.12 As shown in (c), the above step 13 may include: using an organic polymer material to coat the surface of the entire device to form an organic polymer film (i.e., the diaphragm 30), that is, the diaphragm 30 covers multiple piezoelectric vibration units 20 and the surface of the entire cavity to be formed area 101a, so that a raised portion will be formed corresponding to the position of the raised structure 301a in the portion of the diaphragm 30 located above the cavity to be formed area 101a, and the raised portion is the undulating portion 301.

[0100] It should be understood that a raised portion (301) is formed at the position where the diaphragm 30 covers the raised structure 301a, and the morphology (such as shape, size, etc.) of the raised portion (301) is basically consistent with the raised structure 301a. For the relevant settings of the raised structure 301a, please refer to the relevant description in the previous text, which will not be repeated here.

[0101] Step 14: Reference Fig.13 As shown, a hole 302 is formed at the position of the diaphragm 30 at the protruding structure 301 a , and the protruding structure 301 a is removed through the hole 302 .

[0102] In some possible implementations, step 14 may include: Fig.13 As shown in (a), a photoresist PR is first coated on the surface of the diaphragm 30 and patterned; then, referring to Fig.13 As shown in (b), the diaphragm 30 is etched (dry etching or wet etching) by the patterned photoresist PR to form a hole 302 at the position of the protruding structure 301a; Fig.13 As shown in (c), the protruding structure 301a is removed through the hole 302, and the remaining photoresist PR is removed at the same time.

[0103] Step 15: Reference Fig.13 As shown in (d), etching is performed from the back side of the substrate 10 to form a cavity 101 through the substrate in the cavity to be formed region 101a.

[0104] In some possible implementations, when the substrate 10 is a first silicon-based layer (11) and a SiO2 layer (12) in SOI, the above step 15 may include: Fig.13As shown in (d), a dry etching or wet etching process is used to etch the first silicon-based layer (11) and the SiO2 layer (12) located in the cavity to be formed area 101a from the back to form the cavity 101. The first silicon-based layer (11) and the SiO2 layer (12) are located around the cavity 101. The remaining parts form a frame structure 102, and the frame structure 102 is located at the bottom of the multiple piezoelectric vibration units 20 as a supporting structure.

[0105] Production method 2

[0106] The present application embodiment also provides another Figure 3 The manufacturing method of the MEMS speaker is illustrated. The manufacturing method is described by taking the undulating part 301 as a convex part as an example.

[0107] like Fig.14 As shown, the production method may include:

[0108] Step 21: Reference Fig.15 As shown in (a), a plurality of piezoelectric vibration units 20 are manufactured on a substrate 10; wherein the plurality of piezoelectric vibration units 20 are dispersedly arranged along the edge of a cavity to-be-formed region 101a.

[0109] Step 22: Reference Fig.15 As shown in (b), a protruding structure 301a is formed on the surface of the substrate in the cavity to be formed area 101a.

[0110] Step 23: Reference Fig.15 As shown in (c), a diaphragm 30 is formed on the surface of the piezoelectric vibration unit 20 using an organic polymer material, and extends to cover the entire cavity to be formed area 101a, so as to form a protrusion (301) at the position where the diaphragm 30 covers the protrusion structure 301a.

[0111] The above steps 21, 22 and 23 are respectively substantially the same as the steps 11, 12 and 13 in the above-mentioned production method 1. For the descriptions of steps 21, 22 and 23, reference may be made to the above-mentioned steps 11, 12 and 13, which will not be repeated here.

[0112] The important difference from the above-mentioned production method 1 is:

[0113] Step 24: Reference Fig.15 As shown in (d), etching is performed from the back side of the substrate 10 to form a cavity 101 through the substrate in the cavity to be formed area 101a, and the protruding structure 301a is removed.

[0114] In some possible implementations, when the substrate 10 is a first silicon-based layer (11) and a SiO2 layer (12) in SOI, the above step 24 may include: Fig.15 As shown in (d), the first silicon-based layer (11) and the SiO2 layer (12) located in the cavity to be formed area 101a are etched from the back by an etching process to form the cavity 101, and the protruding structure 301a is removed by etching. The first silicon-based layer (11) and the SiO2 layer (12) are located around the cavity 101. The remaining parts form a frame structure 102, and the frame structure 102 is located at the bottom of the multiple piezoelectric vibration units 20 as a supporting structure.

[0115] In the aforementioned manufacturing method 1, a hole 302 is formed on the diaphragm 30, and the protruding structure 301a is removed through the hole 302. In contrast, in the manufacturing method 2, the hole 302 does not need to be formed on the diaphragm 30, and etching is performed directly from the back side of the substrate 10, and the protruding structure 301a is removed from the back side while the cavity 101 is formed.

[0116] Production method three

[0117] The present application embodiment also provides another Figure 5 The manufacturing method of the MEMS speaker is illustrated. The manufacturing method is described by taking the undulating portion 301 as a concave portion as an example.

[0118] like Fig.16 As shown, the production method may include:

[0119] Step 31: Reference Fig.17 As shown in (a), a plurality of piezoelectric vibration units 20 are manufactured on a substrate 10; wherein the plurality of piezoelectric vibration units 20 are dispersedly arranged along the edge of a cavity to-be-formed region 101a.

[0120] The above step 31 is basically the same as step 11 in the above-mentioned production method 1. For the description of step 31, please refer to the above-mentioned step 11, which will not be repeated here.

[0121] Step 32: Reference Fig.17 As shown in (b), the surface of the substrate 10 located in the cavity to be formed area 101a is etched to form a recessed structure 301b.

[0122] In some possible implementations, for example Fig.17 As shown in (b), the SiO2 layer (12) located in the cavity to be formed area 101a is etched to form a recessed structure 301b; the recessed structure 301b can also be called a recessed undulating structure. Of course, according to actual needs, in order to increase the depth of the recessed structure 301b, etching can be performed from the surface of the SiO2 layer (12) downward to the first silicon-based layer (11).

[0123] Step 33: Reference Fig.17As shown in (c), a diaphragm 30 is formed on the surface of the piezoelectric vibration unit 20 using an organic polymer material, and extends to cover the entire cavity to be formed area 101a, so as to form a recessed portion (301) at the position where the diaphragm 30 covers the recessed structure 301b.

[0124] In some possible implementations, for example Fig.17 As shown in (c), the above step 33 may include: using an organic polymer material to coat the surface of the entire device to form an organic film (i.e., a diaphragm 30); in this case, the diaphragm 30 covers multiple piezoelectric vibration units 20 and the surface of the entire cavity to be formed area 101a, so that the portion of the diaphragm 30 located above the cavity to be formed area 101a, covering the position of the recessed structure 301b will correspond to the formed recessed portion; the recessed portion is the undulating portion 301.

[0125] Step 34: Reference Fig.17 As shown in (d), etching is performed from the back side of the substrate 10 to form a cavity 101 through the substrate in the cavity to be formed area 101a.

[0126] In some possible implementations, the above step 34 may include: when the substrate 10 adopts the first silicon-based layer (11) and the SiO2 layer (12) in SOI, referring to Fig.17 As shown in (d), the above step 34 may include: using a dry etching or wet etching process to etch the first silicon-based layer (11) and the SiO2 layer (12) from the back side, and removing the first silicon-based layer (11) and the SiO2 layer (12) located in the cavity to be formed area 101a to form the cavity 101. The first silicon-based layer (11) and the SiO2 layer (12) are located around the cavity 101. The remaining portion forms a frame structure 102, and the frame structure 102 is located at the bottom of the plurality of piezoelectric vibration units 20 as a supporting structure.

[0127] It should be understood that the sequence numbers of the above processes do not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0128] For other related contents in the above-mentioned production method, you can refer to the corresponding parts in the above-mentioned structural embodiment, which will not be repeated here; for other setting structures in the above-mentioned structural embodiment, you can refer to the above-mentioned production method and related production methods for adjustment, which will not be repeated here one by one.

[0129] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A micro-electromechanical system (MEMS) device, characterized in that: include: A substrate, wherein the substrate includes a cavity and a frame structure surrounding the cavity; A plurality of piezoelectric vibration units, wherein the plurality of piezoelectric vibration units are dispersedly arranged on the frame structure; A diaphragm, wherein the diaphragm is disposed on the plurality of piezoelectric vibration units and covers the entire cavity; The diaphragm is made of an organic film, and the portion of the diaphragm located above the cavity has at least one undulating portion.

2. The MEMS device according to claim 1, characterized in that: The at least one undulating portion includes: a convex portion and / or a concave portion.

3. The MEMS device according to claim 1 or 2, characterized in that: The diaphragm is provided with holes at the position of the undulating part, and the hole has a diameter of 0.5 μm to 5 μm.

4. The MEMS device according to any one of claims 1 to 3, characterized in that: An extending direction of the at least one undulating portion is consistent with a direction of inner edges of the plurality of piezoelectric vibration units.

5. The MEMS device according to claim 4, characterized in that: The cross section of the undulating portion is rectangular or trapezoidal.

6. The MEMS device according to any one of claims 1 to 5, characterized in that: The distribution pattern of the at least one undulating portion on the diaphragm is a symmetrical pattern.

7. The MEMS device according to any one of claims 1 to 5, characterized in that: The distribution pattern of the at least one undulating portion on the diaphragm is an asymmetric pattern.

8. The MEMS device according to any one of claims 1 to 7, characterized in that: The substrate comprises a stacked silicon-based layer and a first dielectric layer; the first dielectric layer is located between the silicon-based layer and the plurality of piezoelectric vibration units; and the first dielectric layer comprises SiO2.

9. The MEMS device according to any one of claims 1 to 8, characterized in that: The piezoelectric vibration unit includes: a vibration layer, a first electrode layer, a piezoelectric layer, and a second electrode layer which are stacked in sequence; wherein the vibration layer is closer to the substrate than the first electrode layer.

10. The MEMS device according to claim 9, characterized in that: The substrate and the vibration layer are made of SOI.

11. A method for manufacturing a MEMS device, characterized in that: include: A plurality of piezoelectric vibration units are fabricated on a substrate; wherein the plurality of piezoelectric vibration units are arranged along the edge of the cavity to be formed area; forming at least one undulating structure on the surface of the substrate located in the area where the cavity is to be formed; Using an organic polymer material to form a diaphragm on the surface of the piezoelectric vibration unit, and extending it to cover the entire area to be formed of the cavity, so as to form an undulating portion at a position where the diaphragm covers the undulating structure; Etching is performed from the back side of the substrate to form a cavity through the substrate in the region where the cavity is to be formed.

12. The method for manufacturing a MEMS device according to claim 9, characterized in that: The method of manufacturing a plurality of piezoelectric vibration units on a substrate comprises: Providing an SOI; wherein the SOI comprises a first silicon-based layer, a first dielectric layer, and a second silicon-based layer; A first electrode layer, a piezoelectric layer, and a second electrode layer are sequentially manufactured on the second silicon-based layer, and the second electrode layer, the piezoelectric layer, the first electrode layer, and the second silicon-based layer are etched to form the plurality of piezoelectric vibration units.

13. The method for manufacturing a MEMS device according to claim 11 or 12, characterized in that: The forming of at least one undulating structure on the surface of the substrate located in the area where the cavity is to be formed comprises: forming a convex structure as the undulating structure on the surface of the substrate located in the area where the cavity is to be formed; After the diaphragm is formed on the surface of the piezoelectric vibration unit by using the organic polymer material and extends to cover the entire area to be formed of the cavity, the manufacturing method further comprises: forming a hole on the diaphragm and removing the at least one undulating structure through the hole; Alternatively, etching from the back side of the substrate to form a cavity through the substrate in the cavity to be formed area includes: etching from the back side of the substrate to form a hole through the substrate in the cavity to be formed area, and removing the protruding structure.

14. The method for manufacturing a MEMS device according to claim 11 or 12, characterized in that: The step of forming a relief structure on the surface of the substrate in the area where the cavity is to be formed comprises: The surface of the substrate located in the area where the cavity is to be formed is etched to form a recessed structure as the undulating structure.

15. An electronic device, characterized in that: It comprises a controller and the MEMS device according to any one of claims 1 to 10, wherein the MEMS device is connected to the controller, and the controller is used to control the multiple piezoelectric vibration units in the MEMS device to drive the diaphragm to vibrate.

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