Electromagnetic loudspeaker piston-motion MEMS loudspeaker and method of manufacturing the same

Abstract

The application discloses an electromagnetic large-sound-resistance piston motion MEMS loudspeaker and a manufacturing method thereof. The electromagnetic large-sound-resistance piston motion MEMS loudspeaker comprises a base, a cavity, an electromagnetic driving assembly, a connecting assembly and a diaphragm. The base comprises a base and a supporting structure extending along the thickness direction of the base, and the supporting structure is surrounded to form the cavity. The connecting assembly is used for connecting the diaphragm and the supporting structure. The diaphragm is a suspended structure and is suspended in the cavity. The diaphragm is not coplanar with the connecting assembly. The vertical displacement range of the diaphragm is generally not more than the cavity height range. The electromagnetic driving assembly comprises a movable part and a fixed part. The movable part constitutes a part of the diaphragm and comprises one of a coil and a magnetic material. The fixed part is located in the base. The electromagnetic driving assembly drives the diaphragm to make piston motion along the vertical direction through electromagnetic force.

Description

Technical Field

[0001] This invention belongs to the field of electro-optical conversion of MEMS acoustic devices, and relates to an electromagnetic MEMS loudspeaker and its manufacturing method, which can be applied to consumer electronics or medical electronics. Background Technology

[0002] The core specification of MEMS loudspeakers is the sound pressure level (SPL). Since the output SPL of a loudspeaker is proportional to the square of the frequency and the first power of the diaphragm displacement, the SPL is usually low at low frequencies (20Hz to 1kHz). Under the condition of device size in the mm or even μm range, it is very difficult to achieve a high SPL in the low frequency range with a fixed diaphragm loudspeaker. Therefore, loudspeakers based on open piston motion modes of the drive structure are required.

[0003] Speakers based on an open piston motion mode driven by a large driving structure have a wide range of motion displacement, but they suffer from acoustic short-circuiting between the front and rear cavities. When the diaphragm vibrates, the front and rear cavities simultaneously generate audio signals with opposite phases. If there is a large air gap between the front and rear cavities, the audio signals from both cavities will overlap and weaken the audio signal generated by the speaker. This corresponds to the acoustic impedance of the air gap between the front and rear cavities. Without affecting the vibration of the air spring in the rear cavity, the smaller the air gap, the greater the acoustic impedance between the front and rear cavities, and the greater the conversion coefficient between the energy generated by the diaphragm's mechanical motion and the energy radiated into the air by the front cavity, thus enabling the generation of a larger SPL (Sound Power Proportion).

[0004] Commonly used MEMS loudspeaker driving mechanisms mainly include electrostatic MEMS loudspeakers, electromagnetic MEMS loudspeakers, piezoelectric MEMS loudspeakers, and electrothermal MEMS loudspeakers. Among them, electromagnetic MEMS loudspeakers have advantages such as low driving voltage, high driving force, mature fabrication process, and low device power consumption. Therefore, it is necessary to provide a high-resistivity piston-motion loudspeaker based on an electromagnetic driving structure and its manufacturing method. This high-resistivity piston-motion loudspeaker based on an electromagnetic driving structure can both induce large displacement movement of the diaphragm and provide sufficiently large acoustic impedance, thereby improving energy conversion efficiency and increasing the loudspeaker's output sound pressure level. Summary of the Invention

[0005] One of the main objectives of this invention is to provide an electromagnetically typed, high-impedance, piston-motion MEMS loudspeaker. Unlike the conventional piston loudspeaker's coplanar connection structure, the electromagnetically typed, high-impedance, piston-motion MEMS loudspeaker disclosed in this invention employs a concealed connection structure that is not coplanar with the diaphragm. The vertical displacement range of the diaphragm is within the cavity height range formed by the support structure extending along the thickness direction of the base. While maintaining the large displacement advantage of piston loudspeakers, the concealed connection structure significantly alleviates the problem of severe air leakage caused by structural and manufacturing limitations, increasing the acoustic impedance of the front and rear cavities of the piston-motion loudspeaker during operation, thereby effectively improving the output sound pressure level. Furthermore, by optimizing the diaphragm structure, support structure, and other components of the piston loudspeaker with the aforementioned concealed connection structure, the length and cross-sectional area of ​​the air gap between the front and rear cavities and the opening of the base can be adjusted, further improving the acoustic impedance and output sound pressure level.

[0006] To address the technical problem that there is currently no feasible manufacturing method for the electromagnetic high-impedance piston-moving MEMS loudspeaker, the second main objective of this invention is to provide a manufacturing method for an electromagnetic high-impedance piston-moving MEMS loudspeaker. This method employs MEMS surface micromachining technology and MEMS volume micromachining technology, utilizing SOI and cavity-SOI with a cavity structure to reduce the requirements for etching precision in the processing technology, thereby realizing the manufacturing of an electromagnetic high-impedance piston-moving MEMS loudspeaker.

[0007] One of the objectives of this invention is achieved through the following technical solution:

[0008] This invention discloses an electromagnetic high-impedance piston-motion MEMS loudspeaker, characterized by: a substrate, a cavity, an electromagnetic drive assembly, a connecting assembly, and a diaphragm; the substrate includes a base and a support structure extending along the thickness direction of the base, the support structure surrounding the cavity; the connecting assembly connects the diaphragm and the support structure; the diaphragm is a suspended structure suspended within the cavity; the diaphragm and the connecting assembly are not coplanar, the diaphragm being located above or below the connection point between the connecting assembly and the support structure; the vertical displacement range of the diaphragm generally does not exceed the cavity height range; the electromagnetic drive assembly includes a movable part and a fixed part; the movable part constitutes part of the diaphragm; the movable part includes one of a coil and a magnetic material; the fixed part is located within the substrate; the electromagnetic drive assembly drives the diaphragm to perform piston-like movement in the vertical direction via electromagnetic force.

[0009] The electromagnetic high impedance piston motion MEMS loudspeaker disclosed in this invention is characterized in that: the connecting component comprises one or more layers of material, and the connecting component generates thermal stress and deformation during its manufacturing process. The deformation can be adjusted by changing the material, thickness, length, and growth process, thereby pre-setting the position of the diaphragm.

[0010] The electromagnetic high impedance piston motion MEMS loudspeaker disclosed in this invention is characterized in that: the connecting component includes at least one layer of material and a heating resistor; after the device is fabricated, the deformation of the connecting component is adjusted by adjusting the magnitude of the current injected into the resistor, thereby adjusting the position of the diaphragm.

[0011] Based on the electromagnetic piston-motion MEMS loudspeaker with a concealed connection structure, the diaphragm and support structures of the loudspeaker are further optimized. Specifically, the shape, size, and number of openings in the base parallel to the diaphragm are optimized; the distance between the diaphragm and the support structure extending along the thickness of the base in the direction parallel to the diaphragm is minimized; the overlap distance between the diaphragm and the support structure extending along the thickness of the base in the direction perpendicular to the diaphragm is maximized; and the shape of the support structure extending along the thickness of the base is optimized. This controls air leakage during loudspeaker operation, further increasing the acoustic impedance of the front and rear cavities and the loudspeaker's output sound pressure level. Electromagnetic MEMS actuators offer advantages such as low driving voltage, high driving force, and mature manufacturing processes. By employing MEMS surface micromachining and MEMS volume micromachining technologies, and utilizing SOI and cavity-SOI with a cavity structure, the requirements for etching accuracy in the processing technology are reduced, the complexity of the processing technology is reduced, the device feasibility is improved, and the consistency of the device structure is improved. This allows for a more accurate reduction in the spacing between the diaphragm and the support structure extending along the thickness direction of the base in the direction parallel to the diaphragm, and an increase in the overlap distance between the diaphragm and the support structure extending along the thickness direction of the base in the direction perpendicular to the diaphragm, thereby controlling the shape of the support structure.

[0012] The working method of the electromagnetic high-impedance piston-motion MEMS loudspeaker disclosed in this invention is as follows: In a magnetic field environment generated by a magnetic material, the direction of the applied electrical signal of the energized coil is changed, thereby generating an electromagnetic force perpendicular to the diaphragm direction, causing the diaphragm to vibrate in a piston-like motion along the vertical direction. The diaphragm, vibrating in a piston-like motion along the vertical direction, drives the air inside the vibration cavity to move, thereby generating a sound wave signal. Since the diaphragm is a suspended structure suspended in the vibration cavity, the diaphragm and the connecting components are not coplanar, and the width of the air gap between the diaphragm edge and the base sidewall is very small, while the length of the air gap between the diaphragm edge and the base sidewall is very large, thus reducing air leakage during the piston-like motion of the diaphragm in the vertical direction, increasing acoustic impedance, thereby reducing sound pressure level loss and improving the sound pressure level of the output sound. Utilizing the advantages of MEMS loudspeakers—device miniaturization, low power consumption, and ease of integration—this invention improves the battery life of MEMS loudspeakers and broadens their application range.

[0013] Preferably, the electromagnetic high-impedance piston-motion MEMS loudspeaker includes two structures based on the placement of the magnetic material and the metal coil. Structure 1: The metal coil is embedded within the diaphragm structure, the magnetic material is located in the speaker's base, the movable part is the coil, and the fixed part is the magnetic material; this is a coil-diaphragm integrated electromagnetic high-impedance piston-motion MEMS loudspeaker. Structure 2: The magnetic material is embedded within the diaphragm structure, the metal coil is located in the speaker's base, the movable part is the magnetic material, and the fixed part is the coil; this is a magnetic material-diaphragm integrated electromagnetic high-impedance piston-motion MEMS loudspeaker.

[0014] The second objective of this invention is achieved through the following technical solution:

[0015] The present invention discloses a method for manufacturing an electromagnetic high-impedance piston-motion MEMS loudspeaker, used to manufacture the coil-diaphragm integrated electromagnetic high-impedance piston-motion MEMS loudspeaker, comprising the following steps:

[0016] Step 1: Provide a conventional SOI wafer, the SOI wafer including a first silicon layer, a second silicon layer, and a silicon oxide layer sandwiched between the first silicon layer and the second silicon layer;

[0017] Step 2: Deposit and pattern the elastic layer material of the connection components on the surface of the first silicon layer of the SOI wafer, forming connection components and diaphragm components with specific shapes on the surface of the first silicon layer. The connection components include one, two, or more sets of connection units, where one set of connection units is composed of an elastic layer and a conductive metal layer, and the remaining connection units are composed of an elastic layer, ensuring that the diaphragm can move perpendicular to the diaphragm direction. The diaphragm assembly is composed of a first silicon layer of predetermined thickness or a first silicon layer of predetermined thickness, an elastic layer, and a conductive metal layer. In the horizontal direction, the diaphragm assembly is located at the center of the first silicon layer, and the connection components cover the first silicon layer and are evenly distributed around the outside of the diaphragm assembly. At this time, the connection components cover the surface of the first silicon layer and cannot move freely;

[0018] Step 3: Etch the first silicon layer in the SOI wafer from the direction close to the first silicon layer to the diaphragm position to form a groove structure;

[0019] Step 4: Electroplating the groove structure formed by etching the first silicon layer to form a metal coil structure;

[0020] Step 5: Deposit and pattern a conductive metal layer for the connecting component from the direction of the first silicon layer. The conductive metal layer of the connecting component covers the outer starting position of the metal coil structure, thereby supplying power to the metal coil in the diaphragm assembly through the conductive metal layer of the connecting component.

[0021] Step 6: Etch the first silicon layer in the SOI wafer from the direction close to the first silicon layer on the outside of the connection component, etching down to the silicon oxide layer, to determine the size of the device diaphragm;

[0022] Step 7: Perform deep reactive ion back cavity etching on the SOI wafer from the direction of the second silicon layer until the silicon oxide layer is reached, forming the vibration cavity, i.e., the area where the diaphragm performs piston-like motion. The vibration cavity of a predetermined shape is formed by adjusting the deep reactive ion etching rate. The dimensions of the substrate are determined by setting the size of the mask layer deposited on the surface of the second silicon layer during the back cavity etching process, thus forming the substrate.

[0023] Step 8: Perform deep reactive ion back cavity etching on the SOI wafer from the direction of the second silicon layer to etch the support structure around the cavity to form the cavity;

[0024] Step 9: Fill the cavity formed by etching the support structure with magnetic material to provide a magnetic field environment. The filled magnetic material and the electroplated coil together constitute the driving component of the electromagnetic piston motion speaker.

[0025] Step 10: Etch the silicon oxide layer on the SOI wafer from the direction closest to the second silicon layer;

[0026] Step 11: Etch the first silicon layer from the direction approaching the SOI wafer, between the gap on the surface of the first silicon layer where the connection component is located and the diaphragm is located. Etch a portion of the silicon layer beneath the connection component, thereby separating the connection component from the first silicon layer. The first silicon layer beneath the connection component, evenly distributed around the diaphragm assembly, is not completely etched. A predetermined thickness of the first silicon layer remains beneath the partially etched first silicon layer. The thinner first silicon layer near the outer edge and the thicker, unetched first silicon layer at the center form the diaphragm assembly. Viewed from the direction of the second silicon layer, the diaphragm assembly partially obscures the connection component, i.e., the hidden connection structure. The coil-diaphragm integrated electromagnetic high-resistivity piston-motion MEMS loudspeaker is thus fabricated.

[0027] The present invention discloses a method for manufacturing an electromagnetically typed high-impedance piston-motion MEMS loudspeaker, used to manufacture the magnetic material-diaphragm integrated electromagnetically typed high-impedance piston-motion MEMS loudspeaker, comprising the following steps:

[0028] Step 1: Provide an SOI wafer, the SOI wafer comprising a first silicon layer, a second silicon layer, and a silicon oxide layer sandwiched between the first silicon layer and the second silicon layer;

[0029] Step 2: Deposit and pattern the elastic layer material of the connection components on the surface of the first silicon layer of the SOI wafer, forming connection components and diaphragm components with specific shapes on the surface of the first silicon layer. The electromagnetic connection components include one, two, or more sets of connection units, which are composed of elastic layers to ensure that the diaphragm can move perpendicular to the diaphragm direction. The diaphragm assembly is composed of a first silicon layer of predetermined thickness or a first silicon layer of predetermined thickness and an elastic layer. In the horizontal direction, the diaphragm assembly is located at the center of the first silicon layer, and the connection components cover the first silicon layer and are evenly distributed around the outside of the diaphragm assembly. At this time, the connection components cover the surface of the first silicon layer and cannot move freely;

[0030] Step 3: Etch the first silicon layer in the SOI wafer at the location of the diaphragm from a direction close to the first silicon layer;

[0031] Step 4: Fill the groove structure formed by etching the first silicon layer with magnetic material to provide a magnetic field environment;

[0032] Step 5: Etch the first silicon layer in the SOI wafer from the direction close to the first silicon layer on the outside of the connection component, etching down to the silicon oxide layer, to determine the size of the device diaphragm;

[0033] Step Six: Perform deep reactive ion back cavity etching on the SOI wafer from the direction of the second silicon layer until the silicon oxide layer is reached, forming the vibration cavity, i.e., the area where the diaphragm performs piston-like motion. The vibration cavity of a predetermined shape is formed by adjusting the deep reactive ion etching rate. The dimensions of the substrate are determined by setting the size of the mask layer deposited on the surface of the second silicon layer during the back cavity etching process, thus forming the substrate.

[0034] Step 7: Perform deep reactive ion back cavity etching on the SOI wafer from the direction of the second silicon layer to etch the support structure around the cavity and form a groove structure;

[0035] Step 8: Electroplating is performed on the groove structure etched into the support structure to form a metal coil structure. The electroplated coil and the filling magnetic material together constitute the driving component of the electromagnetic piston-motion loudspeaker;

[0036] Step 9: Etch the silicon oxide layer on the SOI wafer from the direction closest to the second silicon layer;

[0037] Step 10: Etch the first silicon layer from the direction approaching the SOI wafer, between the gap on the surface of the first silicon layer where the connection component is located and the diaphragm is located. Etch a portion of the silicon layer beneath the connection component, thereby separating the connection component from the first silicon layer. The first silicon layer beneath the connection component, evenly distributed around the diaphragm assembly, is not completely etched. A predetermined thickness of the first silicon layer remains beneath the partially etched first silicon layer. The thinner first silicon layer near the outer edge and the thicker, unetched first silicon layer at the center form the diaphragm assembly. Viewed from the direction of the second silicon layer, the diaphragm assembly partially obscures the connection component, i.e., the hidden connection structure. The electromagnetic high-resistivity piston-motion MEMS loudspeaker is now complete.

[0038] To achieve a loudspeaker structure with high impedance characteristics, as a further improvement, the SOI described in step one includes a three-layer SOI and a cavity-SOI with a cavity structure. The cavity-SOI is used to increase the overlap distance between the diaphragm and the support structure extending along the thickness direction of the base in the electromagnetic high impedance piston motion MEMS loudspeaker in the direction perpendicular to the diaphragm, or to reduce the spacing between the diaphragm and the support structure extending along the thickness direction of the base in the direction parallel to the diaphragm.

[0039] To simplify the process steps, as a further improvement, the cavity structure of the cavity-SOI described in step one is located in the device layer or the handle layer.

[0040] To improve device stability, as a further improvement, the thickness of the cavity structure located in the device layer in the cavity-SOI described in step one shall not exceed 50% of the thickness of the device layer.

[0041] Beneficial effects:

[0042] 1. The electromagnetic high impedance piston motion MEMS loudspeaker and its manufacturing method disclosed in this invention, since the diaphragm is connected to the support structure through the connecting component, the displacement that the diaphragm can reach during vibration is not limited by the support structure compared with the diaphragm that is fixed at the edge, thereby increasing the vibration amplitude of the diaphragm and thus improving the output sound pressure level of the loudspeaker.

[0043] 2. The electromagnetic high-resistivity piston-motion MEMS loudspeaker and its manufacturing method disclosed in this invention feature a concealed connection structure, which increases the acoustic impedance between the front and rear cavities of the piston loudspeaker during operation, thereby improving the loudspeaker's output sound pressure level. Utilizing the advantages of MEMS loudspeakers—miniaturization, low power consumption, and ease of integration—this invention improves the battery life of MEMS loudspeakers and broadens their application range. Furthermore, the MEMS loudspeaker manufacturing method features wafer-level fabrication, a highly standardized process, and strong device consistency. Employing an electromagnetic drive component, which requires low driving voltage, allows for large motion displacement, and uses readily available and simple consumables, it can provide a wide range of displacement for the loudspeaker diaphragm, resulting in a higher output sound pressure level.

[0044] 3. The electromagnetic high-resistivity piston-motion MEMS loudspeaker and its manufacturing method disclosed in this invention, because the diaphragm and the connecting component are not coplanar, the displacement range of the diaphragm is within the height range of the vibration cavity, reducing the cross-sectional area of ​​the air gap between the front and rear cavities during the piston-like movement of the diaphragm in the vertical direction, thus alleviating air leakage. Furthermore, based on the principle of increasing the length of the air gap between the front and rear cavities and reducing the cross-sectional area of ​​the air gap between the front and rear cavities, the diaphragm and support structure of the piston-motion loudspeaker with a hidden connecting structure are optimized to jointly achieve the goal of increasing the acoustic impedance of the front and rear cavities and improving the sound pressure level of the sound output.

[0045] 4. The electromagnetic high-resistivity piston-motion MEMS loudspeaker and its manufacturing method disclosed in this invention adjust the thermal stress generated in the connecting component during its manufacturing process by changing the material, thickness, length, and growth process of the connecting component, thereby changing the deformation of the connecting component and thus pre-setting the position of the diaphragm. Furthermore, the connecting component includes at least one layer of material and a heating resistor. After the device is fabricated, the deformation of the connecting component is adjusted by regulating the current injected into the resistor, thereby adjusting the position of the diaphragm. The above method achieves both pre-setting and changing the position of the diaphragm.

[0046] 5. Addressing the technical problem that there is currently no feasible manufacturing method for the aforementioned electromagnetic piston-motion MEMS loudspeaker and electromagnetic high-impedance piston-motion MEMS loudspeaker, the present invention discloses a manufacturing method for an electromagnetic high-impedance piston-motion MEMS loudspeaker. This method employs MEMS surface micromachining technology and MEMS bulk micromachining technology. By utilizing SOI and cavity-SOI with a cavity structure, the requirements for etching accuracy in the processing technology are reduced, enabling the manufacturing of electromagnetic high-impedance piston-motion MEMS loudspeakers. Furthermore, this method facilitates the manufacturing of electromagnetic high-impedance piston-motion MEMS loudspeakers with different structures. By using consumables with predetermined structures, the process steps are simplified, enabling wafer-level mass production of devices, improving device consistency, and facilitating the design and fabrication of MEMS loudspeakers.

[0047] 6. The electromagnetic high-impedance piston-motion MEMS loudspeaker and its manufacturing method disclosed in this invention preferably produce two types of electromagnetic high-impedance piston-motion MEMS loudspeakers. Structure 1: The metal coil is embedded in the diaphragm structure, and the magnetic material is located on the base of the loudspeaker, which is a coil-diaphragm integrated electromagnetic high-impedance piston-motion MEMS loudspeaker. Structure 2: The magnetic material is embedded in the diaphragm structure, and the metal coil is located on the base of the loudspeaker, which is a magnetic material-diaphragm integrated electromagnetic high-impedance piston-motion MEMS loudspeaker. This invention also constructs manufacturing methods corresponding to the above two electromagnetic high-impedance piston-motion MEMS loudspeaker structures based on the positional layout and material properties of the magnetic material and metal coil, optimizing the process steps, enabling wafer-level mass production of devices, improving device consistency, and facilitating the design and fabrication of MEMS loudspeakers. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structure of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 1 of the present invention;

[0049] Figure 2 This is a cross-sectional schematic diagram of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 1 of the present invention.

[0050] Figure 3 is a process flow diagram of the fabrication process of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 1 of the present invention.

[0051] Wherein: 100—high impedance piston-type loudspeaker, 110—base, 111—base, 112—support structure, 120—drive assembly, 130—diaphragm, 140—connection assembly, 150—cavity.

[0052] Figure 4 This is a schematic diagram of the structure of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 2 of the present invention;

[0053] Figure 5 This is a cross-sectional schematic diagram of the electromagnetic high impedance piston-moving MEMS loudspeaker provided in Embodiment 2 of the present invention.

[0054] Figure 6 is a process flow diagram of the fabrication process of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 3 of the present invention.

[0055] Wherein: 200—high impedance piston motion loudspeaker, 210—base, 211—base, 212—support structure, 220—drive assembly, 230—diaphragm, 240—connection assembly, 250—cavity.

[0056] Figure 7 This is a schematic diagram of the structure of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 3 of the present invention;

[0057] Figure 8 This is a cross-sectional schematic diagram of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 3 of the present invention.

[0058] Figure 9 is a process flow diagram of the fabrication process of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 3 of the present invention.

[0059] Wherein: 300—high impedance piston motion loudspeaker, 310—base, 311—base, 312—support structure, 320—drive assembly, 330—diaphragm, 340—connection assembly, 350—cavity.

[0060] Figure 10 This is a schematic diagram of the structure of the electromagnetic high impedance piston-moving MEMS loudspeaker provided in Embodiment 4 of the present invention;

[0061] Figure 11 This is a cross-sectional schematic diagram of the electromagnetic high impedance piston-moving MEMS loudspeaker provided in Embodiment 4 of the present invention.

[0062] Figure 12 is a process flow diagram of the fabrication process of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 4 of the present invention.

[0063] Wherein: 400—high impedance piston-type loudspeaker, 410—base, 411—base, 412—support structure, 420—drive assembly, 430—diaphragm, 440—connection assembly, 450—cavity.

[0064] Figure 13 This is a schematic diagram of the structure of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 5 of the present invention;

[0065] Figure 14This is a cross-sectional schematic diagram of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 5 of the present invention.

[0066] Figure 15 is a process flow diagram of the fabrication process of the electromagnetic high impedance piston motion MEMS loudspeaker provided in Embodiment 5 of the present invention.

[0067] Wherein: 500—high impedance piston motion loudspeaker, 510—base, 511—base, 512—support structure, 520—drive assembly, 530—diaphragm, 540—connection assembly, 550—cavity. Detailed Implementation

[0068] To better illustrate the purpose and advantages of the present invention, the invention will be further described below in conjunction with the accompanying drawings and examples.

[0069] It should be noted that all directional indications (such as up, down, left, right, front, back, inside, outside, top, bottom, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship between the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0070] Example 1

[0071] Please see Figure 1 According to Embodiment 1 of the present invention, an electromagnetic high-resistivity piston-motion MEMS loudspeaker 100 is provided. This electromagnetic high-resistivity piston-motion loudspeaker is a coil-diaphragm integrated electromagnetic high-resistivity piston-motion loudspeaker, including a substrate 110, an electromagnetic drive assembly 120, a diaphragm 130, a connecting assembly 140, and a cavity 150. The diaphragm 130 is square, and the cavity 150 has a square cross-section, matching the shape of the diaphragm 130. The electromagnetic drive assembly 120 includes a magnetic filling material 121 and a spiral coil structure 122. The substrate 110 includes a base 111 and a support structure 112 extending along the thickness direction. The connecting assembly 140 includes four sets of connecting units for connecting the support structure 112 and the diaphragm 130. The support structure 112 surrounds and forms the cavity 150.

[0072] Please refer to the cross-sectional diagram. Figure 2Based on the structural design principle of minimizing the spacing between the diaphragm and the supporting structure in the direction parallel to the diaphragm, the electromagnetic high-resistivity piston-motion MEMS loudspeaker 100 provided in Embodiment 1 of this invention has a non-coplanar connection component 140 and diaphragm 130. The projection areas of the connection component 140 and the diaphragm 130 on the horizontal plane overlap, forming a hidden driving structure. The width of the gap between the diaphragm 130 and the supporting structure 112 in the horizontal direction is smaller than the width of the connection component 140, effectively reducing the cross-sectional area of ​​the air gap between the front and rear cavities. During loudspeaker operation, the displacement range of the diaphragm 130 is within the height range of the cavity 150, ensuring that the cross-sectional area of ​​the air gap between the front and rear cavities remains small throughout the entire operation, thereby increasing the acoustic impedance of the front and rear cavities.

[0073] Please refer to the cross-sectional diagram. Figure 2 Based on the structural design principle of adjusting the shape, size, and number of openings in the base parallel to the diaphragm, the electromagnetic high-resistivity piston-motion MEMS loudspeaker 100 provided in Embodiment 1 of the present invention has a through hole at the center of the base 111, and the remaining part of the base is provided with a blocking structure to reduce air leakage between the front and rear cavities, thereby increasing the acoustic impedance of the front and rear cavities.

[0074] Referring to Figure 3, this embodiment of the invention also provides a method S100 for manufacturing an electromagnetic high-resistivity piston-motion MEMS loudspeaker 100, comprising:

[0075] Step S101, referring to FIG3(a), a conventional SOI wafer is provided, the SOI wafer including a first silicon layer 111, a second silicon layer 112 and a silicon oxide layer 121 sandwiched between the first silicon layer and the second silicon layer;

[0076] Step S102, referring to Figure 3(b), an elastic layer material 122 for the connection components is deposited and patterned on the surface of the first silicon layer of the SOI wafer, forming connection components and diaphragm components with specific shapes on the surface of the first silicon layer. The electromagnetic connection components include one, two, or more sets of connection units, wherein one set of connection units is composed of an elastic layer and a conductive metal layer, and the remaining connection units are composed of an elastic layer, ensuring that the diaphragm can move perpendicular to the diaphragm direction. The diaphragm component is composed of a first silicon layer of predetermined thickness or a first silicon layer of predetermined thickness, an elastic layer, and a conductive metal layer. In the horizontal direction, the diaphragm component is located at the center of the first silicon layer, and the connection components cover the first silicon layer and are evenly distributed around the outside of the diaphragm component. At this time, the connection components cover the surface of the first silicon layer and cannot move freely;

[0077] Step S103, referring to FIG3(c), the first silicon layer in the SOI wafer is etched from the direction close to the first silicon layer to the first silicon layer at the diaphragm position to form a spiral groove structure;

[0078] Step S104, referring to Figure 3(d), electroplating is performed on the spiral groove structure formed by etching the first silicon layer to form a metal coil structure 131;

[0079] In step S105, referring to FIG3(e), a conductive metal layer 141 for connecting components is deposited and patterned from the direction of the first silicon layer. The conductive metal layer of the connecting components covers the outer starting position of the metal coil structure, thereby supplying power to the metal coil in the diaphragm assembly through the conductive metal layer of the connecting components.

[0080] Step S106, referring to FIG3(f), the first silicon layer in the SOI wafer is etched from the direction close to the first silicon layer on the outside of the connection component, and etched down to the silicon oxide layer to determine the size of the device diaphragm;

[0081] Step S107, referring to Figure 3(g), deep reactive ion back cavity etching is performed on the SOI wafer from the direction of the second silicon layer until the silicon oxide layer is reached, forming the vibration cavity, i.e., the area where the diaphragm performs piston-like motion. The vibration cavity of a predetermined shape is formed by adjusting the deep reactive ion etching rate. The size of the substrate is determined by setting the size of the mask layer deposited on the surface of the second silicon layer during the back cavity etching process, and the substrate is formed.

[0082] Step S108, referring to Figure 3(h), deep reactive ion back cavity etching is performed on the SOI wafer from the direction of the second silicon layer, and the support structure around the cavity is etched to form an annular cavity;

[0083] Step S109, referring to Figure 3(i), the annular cavity formed by etching the support structure is filled with magnetic material 151 to provide a magnetic field environment. The filled magnetic material and the electroplated coil together constitute the driving component of the electromagnetic piston motion speaker.

[0084] Step S110, referring to FIG3(j), the silicon oxide layer of the SOI wafer is etched from the direction close to the second silicon layer;

[0085] In step S111, referring to Figure 3(k), the first silicon layer is etched from the direction approaching the SOI wafer into the gap between the location of the connecting component and the diaphragm on the surface of the first silicon layer. A portion of the silicon thickness beneath the connecting component is etched, thereby separating the connecting component from the first silicon layer. The first silicon layer beneath the connecting component, which is uniformly distributed around the diaphragm assembly, is not completely etched. A predetermined thickness of the first silicon layer remains beneath the partially etched first silicon layer. The thinner first silicon layer near the outer edge and the thicker, unetched first silicon layer at the center form the diaphragm assembly. Viewed from the direction of the second silicon layer, the diaphragm assembly partially obscures the connecting component, i.e., the hidden connection structure.

[0086] Step S112, referring to Figure 3(l), the blocking material 161 is patterned to complete the fabrication of an electromagnetic high impedance piston-movement MEMS loudspeaker with a through-hole structure and a hidden connection structure.

[0087] Example 2

[0088] Please see Figure 4 According to Embodiment 2 of the present invention, an electromagnetic high-resistivity piston-motion MEMS loudspeaker 200 is provided. This electromagnetic high-resistivity piston-motion loudspeaker is a coil-diaphragm integrated electromagnetic high-resistivity piston-motion loudspeaker, including a substrate 210, an electromagnetic drive assembly 220, a diaphragm 230, a connecting assembly 240, and a cavity 250. The diaphragm 230 is square, and the cavity 250 has a square cross-section, matching the shape of the diaphragm 230. The electromagnetic drive assembly 220 includes a magnetic filling material 221 and a spiral coil structure 222. The substrate 210 includes a base 211 and a support structure 212 extending along the thickness direction. The connecting assembly 240 includes four sets of connecting units for connecting the support structure 212 and the diaphragm 230. The support structure 212 surrounds and forms the cavity 250.

[0089] Please refer to the cross-sectional diagram. Figure 5 Based on the structural design principle of minimizing the spacing between the diaphragm and the supporting structure in the direction parallel to the diaphragm, the electromagnetic high-resistivity piston-motion MEMS loudspeaker 200 provided in Embodiment 2 of the present invention has a non-coplanar connection component 240 and a diaphragm 230. The projection areas of the connection component 240 and the diaphragm 230 on the horizontal plane overlap, forming a hidden driving structure. The width of the gap between the diaphragm 230 and the supporting structure 212 in the horizontal direction is smaller than the width of the connection component 240, effectively reducing the cross-sectional area of ​​the air gap between the front and rear cavities. During loudspeaker operation, the displacement range of the diaphragm 230 is within the height range of the cavity 250, ensuring that the cross-sectional area of ​​the air gap between the front and rear cavities remains small throughout the entire operation, thereby increasing the acoustic impedance of the front and rear cavities.

[0090] Please refer to the cross-sectional schematic diagram Figure 5 Based on the structural design principle that the distance between the diaphragm and the support structure in the direction parallel to the diaphragm is as small as possible, the support structure is discontinuous in the thickness direction and is segmented perpendicular to the diaphragm. In Embodiment 2 of the present invention, the electromagnetic large acoustic resistance piston motion type MEMS speaker 200 is provided, and the cross-sectional view of the support structure 212 is an inverted "convex" shape. To meet the process requirements, the upper side of the cavity 250 has a larger size. After the device is released, in the working state, the displacement range of the diaphragm 230 is within the range of the smaller size of the lower side of the cavity 250, which solves to a certain extent the problem of the large distance between the diaphragm and the support structure in the direction parallel to the diaphragm caused by process limitations, and ensures that the cross-sectional area of the air gap between the front and rear cavities remains at a small value, achieving the purpose of increasing the acoustic resistance of the front and rear cavities.

[0091] Referring to FIG. 6, the present invention embodiment also provides a manufacturing method S200 for an electromagnetic large acoustic resistance piston motion type MEMS speaker 200, including:

[0092] Step S201, referring to FIG. 6(a), provide a conventional SOI wafer, the SOI wafer includes a first silicon layer 211, a second silicon layer 212, and a silicon oxide layer 221 sandwiched between the first silicon layer and the second silicon layer, and the second silicon layer 212 includes a cavity structure with a certain thickness;

[0093] Step S202, referring to FIG. 6(b), deposit and pattern the elastic layer material 222 of the connection component on the surface of the first silicon layer of the SOI wafer, and form a connection component with a specific shape and a diaphragm component on the surface of the first silicon layer. The electromagnetic connection component includes one group, two groups or multiple groups of connection units, where one group of connection units is composed of an elastic layer and a conductive metal layer, and the remaining connection units are composed of an elastic layer, ensuring that the diaphragm moves in a direction perpendicular to the diaphragm. The diaphragm component is composed of a first silicon layer with a predetermined thickness or a first silicon layer with a predetermined thickness, an elastic layer, and a conductive metal layer. In the horizontal direction, the diaphragm component is located at the center position of the first silicon layer, the connection component covers the first silicon layer, and is evenly distributed outside the diaphragm around the diaphragm component. At this time, the connection component covers the surface of the first layer of silicon and cannot move freely;

[0094] Step S203, referring to FIG. 6(c), etch the first silicon layer in the SOI wafer from a direction close to the first silicon layer, and etch a spiral groove structure at the position of the diaphragm;

[0095] Step S204, referring to FIG. 6(d), electroplate the spiral groove structure etched on the first silicon layer to form a metal coil structure 231;

[0096] In step S205, referring to FIG6(e), a conductive metal layer 241 for connecting components is deposited and patterned from the direction of the first silicon layer. The conductive metal layer of the connecting components covers the outer starting position of the metal coil structure, thereby supplying power to the metal coil in the diaphragm assembly through the conductive metal layer of the connecting components.

[0097] Step S206, referring to FIG6(f), the first silicon layer in the SOI wafer is etched from the direction close to the first silicon layer on the outside of the connection component, and etched down to the silicon oxide layer to determine the size of the device diaphragm;

[0098] Step S207, referring to Figure 6(g), deep reactive ion back cavity etching is performed on the SOI wafer from the direction of the second silicon layer until the silicon oxide layer is reached, forming the vibration cavity, i.e., the area where the diaphragm performs piston-like motion. The vibration cavity of a predetermined shape is formed by adjusting the deep reactive ion etching rate. The size of the substrate is determined by setting the size of the mask layer deposited on the surface of the second silicon layer during the back cavity etching process, and the substrate is formed.

[0099] Step S208, referring to Figure 6(h), deep reactive ion back cavity etching is performed on the SOI wafer from the direction of the second silicon layer, and the support structure around the cavity is etched to form an annular cavity;

[0100] Step S209, referring to Figure 6(i), the annular cavity formed by etching the support structure is filled with magnetic material 251 to provide a magnetic field environment. The filled magnetic material and the electroplated coil together constitute the driving component of the electromagnetic piston motion speaker.

[0101] Step S210, referring to FIG6(j), the silicon oxide layer of the SOI wafer is etched from the direction close to the second silicon layer;

[0102] In step S211, referring to Figure 6(k), the first silicon layer is etched from the direction approaching the SOI wafer into the gap between the location of the connecting component and the diaphragm on the surface of the first silicon layer. A portion of the silicon thickness in the first silicon layer beneath the connecting component is etched, thereby separating the connecting component from the first silicon layer. The first silicon layer beneath the connecting component, which is uniformly distributed around the diaphragm assembly, is not completely etched. A predetermined thickness of the first silicon layer remains beneath the partially etched first silicon layer. The thinner first silicon layer near the outer edge and the thicker first silicon layer at the center, which is not etched, form the diaphragm assembly. Viewed from the direction of the second silicon layer, the diaphragm assembly partially obscures the connecting component, i.e., the hidden connecting structure. An electromagnetic high-resistivity piston-motion MEMS loudspeaker with a segmented cavity structure and a hidden connecting structure is thus fabricated.

[0103] Example 3

[0104] Please see Figure 7 According to Embodiment 3 of the present invention, an electromagnetic high-resistivity piston-motion MEMS loudspeaker 300 is provided. This electromagnetic high-resistivity piston-motion loudspeaker is a coil-diaphragm integrated electromagnetic high-resistivity piston-motion loudspeaker, including a substrate 310, an electromagnetic drive assembly 320, a diaphragm 330, a connecting assembly 340, and a cavity 350. The diaphragm 330 is square, and the cavity 350 has a square cross-section, matching the shape of the diaphragm 330. The electromagnetic drive assembly 320 includes a magnetic filling material 321 and a spiral coil structure 322. The substrate 310 includes a base 311 and a support structure 312 extending along the thickness direction. The connecting assembly 340 includes four sets of connecting units for connecting the support structure 312 and the diaphragm 330. The support structure 312 surrounds and forms the cavity 350.

[0105] Please refer to the cross-sectional diagram. Figure 8 Based on the structural design principle of minimizing the spacing between the diaphragm and the supporting structure in the direction parallel to the diaphragm, the electromagnetic high-resistivity piston-motion MEMS loudspeaker 300 provided in Embodiment 3 of this invention features a non-coplanar connection component 340 and a diaphragm 330. The projection areas of the connection component 340 and the diaphragm 330 on the horizontal plane overlap, forming a hidden driving structure. The width of the gap between the diaphragm 330 and the supporting structure 312 in the horizontal direction is smaller than the width of the connection component 340, effectively reducing the cross-sectional area of ​​the air gap between the front and rear cavities. During loudspeaker operation, the displacement range of the diaphragm 330 is within the height range of the cavity 350, ensuring that the cross-sectional area of ​​the air gap between the front and rear cavities remains small throughout the entire operation, thereby increasing the acoustic impedance of the front and rear cavities.

[0106] Please refer to the cross-sectional diagram. Figure 8 Based on the structural design principles of minimizing the spacing between the diaphragm and the supporting structure in the direction parallel to the diaphragm, and ensuring the supporting structure is continuous in the thickness direction but not perpendicular to the diaphragm, forming a certain tilt angle with the diaphragm, the electromagnetic high-resistivity piston-motion MEMS loudspeaker 300 provided in Embodiment 3 of this invention has a supporting structure 312 with a cross-sectional view of an inverted isosceles trapezoid. To meet process requirements, the size of the cavity 350 gradually increases from the base 311 to the diaphragm 230. Compared to a loudspeaker structure where the cavity sidewalls are perpendicular to the diaphragm, in the working state, when the diaphragm 230 moves to a position close to the base 311, the cross-sectional area of ​​the air gap between the front and rear cavities is significantly reduced. This solves to some extent the problem of a large spacing between the diaphragm and the supporting structure in the direction parallel to the diaphragm due to process limitations, thereby increasing the acoustic impedance of the front and rear cavities.

[0107] Referring to Figure 9, this embodiment of the invention also provides a method S300 for manufacturing an electromagnetic high-resistivity piston-motion MEMS loudspeaker 300, comprising:

[0108] Step S301, referring to FIG9(a), a conventional SOI wafer is provided, the SOI wafer including a first silicon layer 311, a second silicon layer 312 and a silicon oxide layer 321 sandwiched between the first silicon layer and the second silicon layer;

[0109] In step S302, referring to Figure 9(b), an elastic layer material 322 for the connection components is deposited and patterned on the surface of the first silicon layer of the SOI wafer, forming connection components and diaphragm components with specific shapes on the surface of the first silicon layer. The electromagnetic connection components include one, two, or more sets of connection units, where one set of connection units is composed of an elastic layer and a conductive metal layer, and the remaining connection units are composed of an elastic layer, ensuring that the diaphragm can move perpendicular to the diaphragm direction. The diaphragm component is composed of a first silicon layer of predetermined thickness or a first silicon layer of predetermined thickness, an elastic layer, and a conductive metal layer. In the horizontal direction, the diaphragm component is located at the center of the first silicon layer, and the connection components cover the first silicon layer and are evenly distributed around the outside of the diaphragm component. At this time, the connection components cover the surface of the first silicon layer and cannot move freely.

[0110] Step S303, referring to FIG9(c), the first silicon layer in the SOI wafer is etched from the direction close to the first silicon layer to the first silicon layer at the diaphragm position to form a spiral groove structure;

[0111] Step S304, referring to Figure 9(d), electroplating is performed on the spiral groove structure formed by etching the first silicon layer to form a metal coil structure 331;

[0112] In step S305, referring to FIG9(e), a conductive metal layer 341 for connecting components is deposited and patterned from the direction of the first silicon layer. The conductive metal layer of the connecting components covers the outer starting position of the metal coil structure, thereby supplying power to the metal coil in the diaphragm assembly through the conductive metal layer of the connecting components.

[0113] Step S306, referring to FIG9(f), the first silicon layer in the SOI wafer is etched from the direction close to the first silicon layer on the outside of the connection component, and etched down to the silicon oxide layer to determine the size of the device diaphragm;

[0114] Step S307, referring to Figure 9(g), deep reactive ion back cavity etching is performed on the SOI wafer from the direction of the second silicon layer until the silicon oxide layer is reached, forming the vibration cavity, i.e., the area where the diaphragm performs piston-like motion. The vibration cavity of a predetermined shape is formed by adjusting the deep reactive ion etching rate. The size of the substrate is determined by setting the size of the mask layer deposited on the surface of the second silicon layer during the back cavity etching process, and the substrate is formed.

[0115] Step S308, referring to Figure 9(h), deep reactive ion back cavity etching is performed on the SOI wafer from the direction of the second silicon layer, and the support structure around the cavity is etched to form an annular cavity;

[0116] Step S309, referring to Figure 9(i), the annular cavity formed by etching the support structure is filled with magnetic material 351 to provide a magnetic field environment. The filled magnetic material and the coil formed by electroplating together constitute the driving component of the electromagnetic piston motion speaker.

[0117] Step S310, referring to FIG9(j), the silicon oxide layer of the SOI wafer is etched from the direction close to the second silicon layer;

[0118] Step S311, referring to Figure 9(k), etching is performed on the first silicon layer from the direction approaching the SOI wafer, between the gap between the location of the connecting component and the diaphragm on the surface of the first silicon layer. A portion of the silicon thickness in the first silicon layer beneath the connecting component is etched, thereby separating the connecting component from the first silicon layer. The first silicon layer beneath the connecting component, which is uniformly distributed around the diaphragm assembly, is not completely etched. A predetermined thickness of the first silicon layer remains beneath the partially etched first silicon layer. The thinner first silicon layer near the outer edge and the thicker first silicon layer at the center, which is not etched, form the diaphragm assembly. Viewed from the direction of the second silicon layer, the diaphragm assembly partially obscures the connecting component, i.e., the hidden connecting structure. An electromagnetic high-resistivity piston-motion MEMS loudspeaker with an inclined cavity and a hidden connecting structure is thus fabricated.

[0119] Example 4

[0120] Please see Figure 10, according to the fourth embodiment of the present invention, an electromagnetic large acoustic resistance piston motion type MEMS speaker 400 is provided. The electromagnetic large acoustic resistance piston motion type speaker is a coil-diaphragm integrated electromagnetic large acoustic resistance piston motion type speaker, and includes a substrate 410, an electromagnetic driving component 420, a diaphragm 430, a connecting component 440, and a cavity 450. Among them, the diaphragm 430 is square, and the cross-section of the cavity 450 is square, matching the shape of the diaphragm 430. The electromagnetic driving component 420 includes a magnetic filling material 421 and a spiral coil structure 422. The substrate 410 includes a base 411 and a support structure 412 extending in the thickness direction. The connecting component 440 includes four groups of connecting units for connecting the support structure 412 and the diaphragm 430. The support structure 412 surrounds to form the cavity 450.

[0121] Please refer to the cross-sectional schematic diagram Figure 11 , based on the structural design principle that the distance between the diaphragm and the support structure in the direction parallel to the diaphragm is as small as possible. For the electromagnetic large acoustic resistance piston motion type MEMS speaker 400 provided in the fourth embodiment of the present invention, the connecting component 440 and the diaphragm 430 are not coplanar. There is an overlapping part in the projection area of the connecting component 440 and the diaphragm 430 on the horizontal plane, which is a hidden driving structure. The gap width between the diaphragm 430 and the support structure 412 in the horizontal direction is smaller than the width of the connecting component 440, effectively reducing the cross-sectional area of the air gap between the front and rear cavities. In the working state of the speaker, the displacement range of the diaphragm 430 is within the height range of the cavity 450, ensuring that the cross-sectional area of the air gap between the front and rear cavities remains small throughout the working process, achieving the purpose of increasing the acoustic resistance between the front and rear cavities.

[0122] Please refer to the cross-sectional schematic diagram Figure 11 , based on the structural design principle that the overlapping distance between the diaphragm and the support structure in the direction perpendicular to the diaphragm is as large as possible. For the electromagnetic large acoustic resistance piston motion type MEMS speaker 400 provided in the fourth embodiment of the present invention, the cross-sectional view of the diaphragm 430 is in the shape of "冖". Compared with the diaphragm structure with a rectangular cross-sectional view, on the basis of controlling the mass of the diaphragm, the overlapping area between the diaphragm 430 and the support structure 412 in the direction perpendicular to the diaphragm 430 is increased, effectively increasing the length of the air gap between the front and rear cavities, achieving the purpose of increasing the acoustic resistance between the front and rear cavities.

[0123] Referring to FIG. 12, the present invention embodiment also provides a manufacturing method S400 for an electromagnetic large acoustic resistance piston motion type MEMS speaker 400, including:

[0124] Step S401, referring to FIG12(a), a conventional SOI wafer is provided. The SOI wafer includes a first silicon layer 411, a second silicon layer 412, and a silicon oxide layer 421 sandwiched between the first silicon layer and the second silicon layer. The first silicon layer 411 includes a cavity structure of a certain thickness.

[0125] In step S402, referring to Figure 12(b), an elastic layer material 422 for the connection components is deposited and patterned on the surface of the first silicon layer of the SOI wafer, forming connection components and diaphragm components with specific shapes on the surface of the first silicon layer. The electromagnetic connection components include one, two, or more sets of connection units, where one set of connection units is composed of an elastic layer and a conductive metal layer, and the remaining connection units are composed of an elastic layer, ensuring that the diaphragm can move perpendicular to the diaphragm direction. The diaphragm assembly is composed of a first silicon layer of predetermined thickness or a first silicon layer of predetermined thickness, an elastic layer, and a conductive metal layer. In the horizontal direction, the diaphragm assembly is located at the center of the first silicon layer, and the connection components cover the first silicon layer and are evenly distributed around the outside of the diaphragm assembly. At this time, the connection components cover the surface of the first silicon layer and cannot move freely.

[0126] Step S403, referring to FIG12(c), the first silicon layer in the SOI wafer is etched from the direction close to the first silicon layer to the first silicon layer at the diaphragm position to form a spiral groove structure;

[0127] Step S404, referring to Figure 12(d), the spiral groove structure formed by etching the first silicon layer is electroplated to form a metal coil structure 431;

[0128] In step S405, referring to FIG12(e), a conductive metal layer 441 for connecting components is deposited and patterned from the direction of the first silicon layer. The conductive metal layer of the connecting components covers the outer starting position of the metal coil structure, thereby supplying power to the metal coil in the diaphragm assembly through the conductive metal layer of the connecting components.

[0129] Step S406, referring to FIG12(f), the first silicon layer in the SOI wafer is etched from the direction close to the first silicon layer on the outside of the connection component, and etched down to the silicon oxide layer to determine the size of the device diaphragm;

[0130] Step S407, referring to Figure 12(g), deep reactive ion back cavity etching is performed on the SOI wafer from the direction of the second silicon layer until the silicon oxide layer is reached, forming the vibration cavity, i.e., the area where the diaphragm performs piston-like motion. The vibration cavity of a predetermined shape is formed by adjusting the deep reactive ion etching rate. The size of the substrate is determined by setting the size of the mask layer deposited on the surface of the second silicon layer during the back cavity etching process, and the substrate is formed.

[0131] Step S408, referring to FIG. 12(h), perform deep reactive ion back cavity etching on the SOI wafer from the direction of the second silicon layer to etch the support structure around the cavity, forming an annular cavity;

[0132] Step S409, referring to FIG. 12(i), fill the annular cavity formed by etching the support structure with magnetic material 451 to provide a magnetic field environment. The filled magnetic material and the coil formed by electroplating together constitute the driving component of the electromagnetic piston motion type speaker;

[0133] Step S410, referring to FIG. 12(j), etch the silicon oxide layer on the SOI wafer from the direction close to the second silicon layer;

[0134] Step S411, referring to FIG. 12(k), etch the first silicon layer on the SOI wafer from the direction close to the first silicon layer, in the gap between the position of the connection component and the position of the diaphragm on the surface of the first silicon layer, etching a part of the thickness of the silicon in the first silicon layer under the connection component, thereby separating the connection component from the first silicon layer. The first silicon layer under the connection component evenly distributed around the diaphragm component and outside the diaphragm component is not completely etched, and a predetermined thickness of the first silicon layer remains under the partially etched first silicon layer. The thinner first silicon layer reserved near the outside and the thicker first silicon layer not etched at the center position form the diaphragm component. From the direction of the second silicon layer, the diaphragm component partially blocks the connection component, that is, the hidden connection structure. An electromagnetic large sound resistance piston motion type MEMS speaker with a "冖" - shaped diaphragm structure and a hidden connection structure is prepared.

[0135] Embodiment Five

[0136] Please refer to Figure 13 , according to Embodiment Five of the present invention, an electromagnetic large sound resistance piston motion type MEMS speaker 500 is provided. The electromagnetic large sound resistance piston motion type speaker is a magnetic material - diaphragm integrated electromagnetic large sound resistance piston motion type speaker, including a substrate 510, an electromagnetic drive component 520, a diaphragm 530, a connection component 540, and a cavity 550. Among them, the diaphragm 530 is square, and the cross - section of the cavity 550 is square, matching the shape of the diaphragm 530. The electromagnetic drive component 520 includes a magnetic filling material 521 and a metal coil structure 522. The substrate 510 includes a base 511 and a support structure 512 extending in the thickness direction. The connection component 540 includes four groups of connection units for connecting the support structure 512 and the diaphragm 530. The support structure 512 surrounds to form the cavity 550.

[0137] Please refer to the cross - sectional schematic diagram Figure 14Based on the structural design principle of minimizing the spacing between the diaphragm and the supporting structure in the direction parallel to the diaphragm, the electromagnetic high-resistivity piston-motion MEMS loudspeaker 500 provided in Embodiment 5 of the present invention has a non-coplanar connection component 540 and a diaphragm 530. The projection areas of the connection component 540 and the diaphragm 530 on the horizontal plane overlap, forming a hidden driving structure. The width of the gap between the diaphragm 530 and the supporting structure 512 in the horizontal direction is smaller than the width of the connection component 540, effectively reducing the cross-sectional area of ​​the air gap between the front and rear cavities. During loudspeaker operation, the displacement range of the diaphragm 530 is within the height range of the cavity 550, ensuring that the cross-sectional area of ​​the air gap between the front and rear cavities remains small throughout the entire operation, thereby increasing the acoustic impedance of the front and rear cavities.

[0138] Please refer to the cross-sectional diagram. Figure 14 Based on the structural design principle of adjusting the shape, size, and number of openings in the base parallel to the diaphragm, the electromagnetic high-resistivity piston-motion MEMS loudspeaker 500 provided in Embodiment 5 of the present invention has a through hole at the center of the base 511, and the remaining part of the base is provided with a blocking structure to reduce air leakage between the front and rear cavities, thereby increasing the acoustic impedance of the front and rear cavities.

[0139] Referring to Figure 3, this embodiment of the invention also provides a manufacturing method S500 for an electromagnetic high-resistivity piston-motion MEMS loudspeaker 500, comprising:

[0140] Step S501, referring to FIG15(a), an SOI wafer is provided, the SOI wafer including a first silicon layer 2-111, a second silicon layer 2-112 and a silicon oxide layer 2-121 sandwiched between the first silicon layer and the second silicon layer;

[0141] Step S502, referring to Figure 15(b), an elastic layer material 2-122 for the connection components is deposited and patterned on the surface of the first silicon layer of the SOI wafer, forming a connection component and a diaphragm assembly with a specific shape on the surface of the first silicon layer. The electromagnetic connection component includes one, two, or more sets of connection units, which are composed of an elastic layer to ensure that the diaphragm can move perpendicular to the diaphragm direction. The diaphragm assembly is composed of a first silicon layer of predetermined thickness or a first silicon layer of predetermined thickness and an elastic layer. In the horizontal direction, the diaphragm assembly is located at the center of the first silicon layer, and the connection components cover the first silicon layer and are evenly distributed around the outside of the diaphragm assembly. At this time, the connection components cover the surface of the first silicon layer and cannot move freely;

[0142] Step S503, referring to FIG15(c), the first silicon layer in the SOI wafer is etched from the direction close to the first silicon layer to the first silicon layer at the diaphragm position;

[0143] Step S504, referring to Figure 15(d), fill the groove structure formed by etching the first silicon layer with magnetic material 2-131 to provide a magnetic field environment;

[0144] Step S505, referring to FIG15(e), the first silicon layer in the SOI wafer is etched from the direction close to the first silicon layer on the outside of the connection component, and etched down to the silicon oxide layer to determine the size of the device diaphragm;

[0145] Step S506, referring to Figure 15(f), deep reactive ion back cavity etching is performed on the SOI wafer from the direction of the second silicon layer until the silicon oxide layer is reached, forming the vibration cavity, i.e., the area where the diaphragm performs piston-like motion. The vibration cavity of a predetermined shape is formed by adjusting the deep reactive ion etching rate. The size of the substrate is determined by setting the size of the mask layer deposited on the surface of the second silicon layer during the back cavity etching process, and the substrate is formed.

[0146] Step S507, referring to Figure 15(g), deep reactive ion back cavity etching is performed on the SOI wafer from the direction of the second silicon layer to etch the support structure around the cavity to form a groove structure;

[0147] In step S508, referring to Figure 15(h), the groove structure formed by etching the support structure is electroplated, and an electroplated layer 2-141 is formed in the groove to form a metal coil structure. The electroplated coil and the filling magnetic material together constitute the driving component of the electromagnetic piston motion loudspeaker;

[0148] Step S509, referring to FIG15(i), the silicon oxide layer of the SOI wafer is etched from the direction close to the second silicon layer;

[0149] In step S510, referring to FIG15(j), the first silicon layer is etched from the direction approaching the SOI wafer into the gap between the location of the connecting component and the diaphragm on the surface of the first silicon layer. A portion of the silicon thickness in the first silicon layer beneath the connecting component is etched, thereby separating the connecting component from the first silicon layer. The first silicon layer beneath the connecting component, which is uniformly distributed around the diaphragm assembly, is not completely etched. A predetermined thickness of the first silicon layer remains beneath the partially etched first silicon layer. The thinner first silicon layer near the outer edge and the thicker first silicon layer at the center, which is not etched, form the diaphragm assembly. Viewed from the direction of the second silicon layer, the diaphragm assembly partially obscures the connecting component, i.e., the hidden connecting structure.

[0150] Step S511, referring to Figure 15(k), pattern the blocking material 2-151 to complete the fabrication of an electromagnetic high-resistance piston-motion MEMS loudspeaker with a through-hole structure and a hidden connection structure.

[0151] The above detailed description further illustrates the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for manufacturing an electromagnetic high-resistivity piston-motion MEMS loudspeaker, characterized in that: Includes the following steps: Step 1: Provide an SOI wafer, the SOI wafer comprising a first silicon layer, a second silicon layer, and a silicon oxide layer sandwiched between the first silicon layer and the second silicon layer; Step 2: Deposit and pattern the elastic layer material of the connection components on the surface of the first silicon layer of the SOI wafer, forming connection components and diaphragm components with specific shapes on the surface of the first silicon layer; the connection components include one, two, or more sets of connection units, wherein one set of connection units is composed of an elastic layer and a conductive metal layer, the conductive metal layer being used to energize the coil structure in the diaphragm; the remaining connection units are composed of elastic layers to ensure that the diaphragm can move perpendicular to the diaphragm direction; the diaphragm assembly is composed of a first silicon layer of predetermined thickness or a first silicon layer of predetermined thickness, an elastic layer, and a conductive metal layer; in the horizontal direction, the diaphragm assembly is located at the center of the first silicon layer, the connection components cover the first silicon layer, and are evenly distributed around the outside of the diaphragm assembly; at this time, the connection components cover the surface of the first silicon layer, and the diaphragm cannot move freely; Step 3: Etch the first silicon layer in the SOI wafer from the direction close to the first silicon layer to the diaphragm position to form a groove structure; Step 4: Electroplating the groove structure formed by etching the first silicon layer to form a metal coil structure; Step 5: Deposit and pattern a conductive metal layer for the connecting component from the direction of the first silicon layer. The conductive metal layer of the connecting component covers the outer starting position of the metal coil structure, thereby supplying power to the metal coil in the diaphragm assembly through the conductive metal layer of the connecting component. Step 6: Etch the first silicon layer in the SOI wafer from the direction close to the first silicon layer on the outside of the connection component, etching down to the silicon oxide layer, to determine the size of the diaphragm; Step 7: Perform deep reactive ion back cavity etching on the SOI wafer from the direction of the second silicon layer until the silicon oxide layer stops, forming a vibration cavity, which is the area where the diaphragm performs piston movement; The vibrational cavity of a predetermined shape category is formed by adjusting the rate of deep reactive ion etching; The size of the substrate is determined by setting the size of the mask layer deposited on the surface of the second silicon layer during the back cavity etching process, and the substrate is formed. Step 8: Perform deep reactive ion back cavity etching on the SOI wafer from the direction of the second silicon layer to etch the support structure around the cavity to form the cavity; Step 9: Fill the cavity formed by etching the support structure with magnetic material to provide a magnetic field environment. The filled magnetic material and the electroplated coil together constitute the driving component of the electromagnetic piston motion speaker. Step 10: Etch the silicon oxide layer on the SOI wafer from the direction closest to the second silicon layer; Step 11: Etch the first silicon layer from the direction of approach to the first silicon layer of the SOI wafer, between the gap between the location of the connecting component and the location of the diaphragm on the surface of the first silicon layer, and etch a portion of the thickness of silicon in the first silicon layer below the connecting component, thereby separating the connecting component from the first silicon layer; The first silicon layer, which is evenly distributed around the diaphragm assembly and is located below the connecting components on the outside of the diaphragm assembly, is not completely etched. A first silicon layer of a predetermined thickness is still retained below the partially etched first silicon layer. The thinner first silicon layer retained near the outside and the thicker first silicon layer that is not etched at the center form the diaphragm assembly. From the direction of the second silicon layer, the diaphragm assembly partially obscures the connecting components, i.e., a hidden connecting structure. An electromagnetic high-resistivity piston-motion MEMS loudspeaker has been successfully fabricated.

2. A method for manufacturing an electromagnetic high-resistivity piston-motion MEMS loudspeaker, characterized in that: Includes the following steps: Step 1: Provide an SOI wafer, the SOI wafer comprising a first silicon layer, a second silicon layer, and a silicon oxide layer sandwiched between the first silicon layer and the second silicon layer; Step 2: Deposit and pattern the elastic layer material of the connection components on the surface of the first silicon layer of the SOI wafer, forming connection components and diaphragm components with specific shapes on the surface of the first silicon layer; the connection components include one, two, or more sets of connection units, which are composed of elastic layers to ensure that the diaphragm can move perpendicular to the diaphragm direction; the diaphragm assembly is composed of a first silicon layer of predetermined thickness or a first silicon layer of predetermined thickness and an elastic layer; in the horizontal direction, the diaphragm assembly is located at the center of the first silicon layer, and the connection components cover the first silicon layer and are evenly distributed around the outside of the diaphragm assembly; at this time, the connection components cover the surface of the first silicon layer and cannot move freely; Step 3: Etch the first silicon layer in the SOI wafer at the location of the diaphragm from a direction close to the first silicon layer; Step 4: Fill the groove structure formed by etching the first silicon layer with magnetic material to provide a magnetic field environment; Step 5: Etch the first silicon layer in the SOI wafer from the direction close to the first silicon layer on the outside of the connection component, etching down to the silicon oxide layer, to determine the size of the diaphragm; Step 6: Perform deep reactive ion back cavity etching on the SOI wafer from the direction of the second silicon layer until the silicon oxide layer stops, forming a vibration cavity, which is the area where the diaphragm performs piston movement; The vibrational cavity of a predetermined shape category is formed by adjusting the rate of deep reactive ion etching; The size of the substrate is determined by setting the size of the mask layer deposited on the surface of the second silicon layer during the back cavity etching process, and the substrate is formed. Step 7: Perform deep reactive ion back cavity etching on the SOI wafer from the direction of the second silicon layer to etch the support structure around the cavity and form a groove structure; Step 8: Electroplating the groove structure etched into the support structure to form a metal coil structure; the electroplated coil and the filling magnetic material together constitute the driving component of the electromagnetic piston motion loudspeaker. Step 9: Etch the silicon oxide layer on the SOI wafer from the direction closest to the second silicon layer; Step 10: Etch the first silicon layer from the direction of approach to the first silicon layer of the SOI wafer, between the gap between the location of the connecting component and the location of the diaphragm on the surface of the first silicon layer, and etch a portion of the thickness of silicon in the first silicon layer below the connecting component, thereby separating the connecting component from the first silicon layer; The first silicon layer, which is evenly distributed around the diaphragm assembly and is located below the connecting components on the outside of the diaphragm assembly, is not completely etched. A first silicon layer of a predetermined thickness is still retained below the partially etched first silicon layer. The thinner first silicon layer retained near the outside and the thicker first silicon layer that is not etched at the center form the diaphragm assembly. From the direction of the second silicon layer, the diaphragm assembly partially obscures the connecting components, i.e., a hidden connecting structure. An electromagnetic high-resistivity piston-motion MEMS loudspeaker has been successfully fabricated.

3. An electromagnetic high-resistivity piston-motion MEMS loudspeaker prepared by the method described in claim 1 or 2, characterized in that: The device includes a substrate, a cavity, an electromagnetic drive assembly, a connecting assembly, and a diaphragm. The substrate includes a base and a support structure extending along the thickness direction of the base, with the support structure surrounding the cavity. The connecting assembly connects the diaphragm and the support structure. The diaphragm is a suspended structure suspended within the cavity. The diaphragm and the connecting assembly are not coplanar, and the diaphragm is located above or below the connection point between the connecting assembly and the support structure. The vertical displacement range of the diaphragm generally does not exceed the height range of the cavity. The electromagnetic drive assembly includes a movable part and a fixed part. The movable part forms part of the diaphragm and includes either a coil or a magnetic material. The fixed part is located within the substrate. The electromagnetic drive assembly drives the diaphragm to perform a piston-like movement in the vertical direction using electromagnetic force.

4. The electromagnetic high-resistivity piston-motion MEMS loudspeaker as described in claim 3, characterized in that: The connecting component comprises one or more layers of material. During its manufacturing process, the connecting component generates thermal stress and deforms. The deformation can be adjusted by changing the material, thickness, length, and growth process, thereby pre-setting the position of the diaphragm.

5. The electromagnetic high-resistivity piston-motion MEMS loudspeaker as described in claim 3, characterized in that: The connecting component includes at least one layer of material and a heating resistor. After the device is fabricated, the deformation of the connecting component is adjusted by adjusting the magnitude of the current injected into the resistor, thereby adjusting the position of the diaphragm.

6. The electromagnetic high-resistivity piston-motion MEMS loudspeaker as described in claim 3, characterized in that: Based on the electromagnetic piston-motion MEMS loudspeaker with a concealed connection structure, the diaphragm and support structures of the loudspeaker are further optimized. Specifically, the shape, size, and number of openings in the base parallel to the diaphragm are optimized; the distance between the diaphragm and the support structure extending along the thickness of the base in the direction parallel to the diaphragm is minimized; the overlap distance between the diaphragm and the support structure extending along the thickness of the base in the direction perpendicular to the diaphragm is maximized; and the shape of the support structure extending along the thickness of the base is optimized. This controls air leakage during loudspeaker operation and further enhances... The acoustic impedance of the large front and rear cavities and the sound pressure level of the speaker output are improved. MEMS surface micromachining technology and MEMS volume micromachining technology are adopted, and SOI and cavity-SOI with cavity structure are utilized to reduce the requirements for etching accuracy in the processing technology, reduce the complexity of the processing technology, improve the device feasibility, and improve the consistency of device structure. This allows for a more accurate reduction of the distance between the diaphragm and the support structure extending along the thickness direction of the base in the direction parallel to the diaphragm, and an increase in the overlap distance between the diaphragm and the support structure extending along the thickness direction of the base in the direction perpendicular to the diaphragm, thereby controlling the shape of the support structure.

7. The electromagnetic high-resistivity piston-motion MEMS loudspeaker as described in claim 3 or 6, characterized in that: In the magnetic field environment generated by the magnetic material, changing the direction of the applied electrical signal of the energized coil generates an electromagnetic force perpendicular to the diaphragm, causing the diaphragm to move in a piston-like motion in the vertical direction. The diaphragm moving in a piston-like motion in the vertical direction causes the air inside the cavity to move, thereby generating a sound wave signal. Since the diaphragm is a suspended structure suspended in the cavity, the diaphragm and the connecting components are not coplanar, and the width of the air gap between the edge of the diaphragm and the sidewall of the base is very small, while the length of the air gap between the edge of the diaphragm and the sidewall of the base is very large, thus reducing air leakage during the piston-like motion of the diaphragm in the vertical direction, increasing acoustic impedance, thereby reducing sound pressure level loss and improving the sound pressure level of the sound output. By leveraging the advantages of MEMS speakers, such as device miniaturization, low power consumption, and ease of integration, we can improve the battery life of MEMS speakers and broaden their application scope.

8. The electromagnetic high-resistivity piston-motion MEMS loudspeaker as described in claim 3, characterized in that: The electromagnetic drive assembly includes a movable part and a fixed part; the movable part forms part of the diaphragm; the movable part is a coil; the fixed part is located in the substrate; the fixed part is made of magnetic material; that is, a coil-diaphragm integrated electromagnetic high impedance piston motion MEMS loudspeaker.

9. The electromagnetic high-resistivity piston-motion MEMS loudspeaker as described in claim 3, characterized in that: The electromagnetic drive assembly includes a movable part and a fixed part; the movable part forms part of the diaphragm; the movable part is made of magnetic material; the fixed part is located in the substrate; the fixed part is a coil; that is, a magnetic material-diaphragm integrated electromagnetic high impedance piston motion MEMS loudspeaker.

10. The method for manufacturing an electromagnetic high-resistivity piston-motion MEMS loudspeaker as described in claim 1 or 2, characterized in that: The SOI mentioned in step one is a three-layer SOI or an SOI with a cavity structure, i.e., cavity-SOI; it is used to increase the overlap distance between the diaphragm and the support structure extending along the thickness direction of the base in the direction perpendicular to the diaphragm in the electromagnetic high impedance piston motion MEMS loudspeaker, or to reduce the spacing between the diaphragm and the support structure extending along the thickness direction of the base in the direction parallel to the diaphragm; the cavity structure of the cavity-SOI mentioned in step one is located in the device layer or the handle layer, and the thickness of the cavity structure located in the device layer in the cavity-SOI mentioned in step one does not exceed 50% of the thickness of the device layer.

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