Sound production device and preparation method thereof

Abstract

The invention discloses a sound production device and a preparation method thereof, and relates to the technical field of micro electro mechanical systems, the sound production device comprises a substrate and a device layer arranged on the substrate, a first sound production unit and a plurality of second sound production units surrounding the periphery of the first sound production unit are arranged in the device layer, the first sound production unit is driven to vibrate and produce sound, the second sound production units are used for vibrating and producing sound under the action of modulation signals, the area occupied by the first sound production unit in the device layer is larger than that occupied by each second sound production unit in the device layer, and the sound production frequency of the first sound production unit is larger than that of each second sound production unit. According to the sound production device and the preparation method thereof provided by the invention, high sound pressure level response in a full frequency band can be realized.

Description

Technical Field

[0001] The present application relates to the technical field of micro-electromechanical systems, and in particular to a sound-generating device and a method for preparing the same. Background Art

[0002] With the development of micro-electro-mechanical system (MEMS) processing technology, more and more sensors are manufactured using MEMS technology, and MEMS speakers are the current hot topic. There are many types of MEMS speakers available (electromagnetic, capacitive, piezoelectric, etc.), among which piezoelectric has the best performance. Mainstream piezoelectric speakers are mainly divided into two types: ultrasonic modulated sound and direct drive sound. Sound pressure level is an important criterion for measuring speaker performance. The frequency response of ultrasonic modulated sound speakers has a higher sound pressure level at low frequencies, while the direct drive form has an excellent response at high frequencies and a higher sound pressure level. The current two mainstream types of speakers still cannot achieve high sound pressure level response in the full frequency band. Summary of the invention

[0003] The purpose of the present application is to provide a sound-generating device and a method for preparing the same, which can achieve high sound pressure level response in the full frequency band.

[0004] On the one hand, an embodiment of the present application provides a sound-emitting device, including a substrate and a device layer arranged on the substrate, in which a first sound-emitting unit and a plurality of second sound-emitting units surrounding the outer periphery of the first sound-emitting unit are arranged, the first sound-emitting unit is driven to vibrate and emit sound, and the second sound-emitting unit is used to vibrate and emit sound under the action of a modulation signal, the area occupied by the first sound-emitting unit in the device layer is larger than the area occupied by each second sound-emitting unit in the device layer, and the sound frequency of the first sound-emitting unit is greater than the sound frequency of the second sound-emitting unit.

[0005] As an implementable manner, a first back cavity is formed in the substrate corresponding to the first sound emitting unit, and the first back cavity includes a large cavity close to the device layer and a plurality of strip cavities connected to a side of the large cavity away from the device layer.

[0006] As an implementable manner, the first sound unit includes a plurality of first cantilever beam structures, which are sequentially arranged along the edge of the first back cavity, and the first cantilever beam structure includes a fixed end arranged on the substrate and a free end extending toward the first back cavity.

[0007] As an implementable manner, the multiple free ends are close to each other and gaps are formed between the multiple first cantilever beams; or, the multiple free ends are close to each other and gaps are formed between the multiple first cantilever beams.

[0008] As an implementable manner, a second back cavity is formed in the substrate corresponding to each second sound emitting unit, and each second sound emitting unit includes a second cantilever beam structure.

[0009] As an implementable manner, a plurality of second sound emitting units are arranged along a circle on the outer circumference of the second sound emitting unit and are arranged in multiple layers.

[0010] On the other hand, an embodiment of the present application provides a method for preparing a sound-emitting device, which is used to prepare the above-mentioned sound-emitting device, including: providing a substrate and forming a device layer on the substrate; etching the device layer to form a first sound-emitting unit and a plurality of second sound-emitting units in the device layer, and the plurality of second sound-emitting units are surrounded by the first sound-emitting unit, wherein an area occupied by the first sound-emitting unit in the device layer is larger than an area occupied by each second sound-emitting unit in the device layer, and a sound frequency of the first sound-emitting unit is greater than a sound frequency of the second sound-emitting unit; a first back cavity corresponding to the first sound-emitting unit and a plurality of second back cavities corresponding to the second sound-emitting units are formed by etching the lower surface of the substrate.

[0011] As an practicable method, providing a substrate includes: providing a first substrate, and opening a first groove and a plurality of second grooves on the upper surface of the first substrate, wherein the plurality of second grooves surround the outer periphery of the first groove, and the cross-section of the first groove is larger than the cross-section of each second groove; filling the first groove and the plurality of second grooves with a sacrificial material to form a first semi-finished product; providing a second substrate, and bonding it to the first semi-finished product, wherein the bonding surface of the first semi-finished product is the upper surface of the sacrificial material; and thinning the second substrate to form a substrate.

[0012] As an practicable method, the substrate includes a buried cavity type silicon-on-insulator, and a first cavity and multiple second cavities are pre-buried on the upper surface of the insulating layer of the silicon-on-insulator. The multiple second cavities are surrounded by the outer periphery of the first cavity, and the cross-section of the first cavity is larger than the cross-section of each second cavity.

[0013] As an practicable method, providing a substrate includes: providing a base plate, and etching a first groove and a plurality of second grooves on the upper surface of the base plate, wherein the plurality of second grooves surround the outer periphery of the first groove, and a cross-section of the first groove is larger than a cross-section of each second groove; and filling a sacrificial material in the first groove and the plurality of second grooves to form a substrate.

[0014] As an implementable method, a first back cavity corresponding to the first sound unit and multiple second back cavities corresponding to the second sound unit are formed by etching the lower surface of the substrate, including: a plurality of strip-shaped cavities are formed by etching the lower surface of the substrate, wherein the plurality of strip-shaped cavities include a plurality corresponding to the first sound unit and one corresponding to each second sound unit; sacrificial material is released to form a large cavity or a small cavity, some of the strip-shaped cavities are connected with the large cavity or the first cavity to form a first back cavity, and some of the strip-shaped cavities are connected with the small cavities one-to-one to form a second back cavity.

[0015] The beneficial effects of the embodiments of the present application include:

[0016] The sound-emitting device provided by the present application includes a substrate and a device layer arranged on the substrate. In the device layer, a first sound-emitting unit and a plurality of second sound-emitting units surrounding the periphery of the first sound-emitting unit are arranged. The first sound-emitting unit is driven to vibrate and emit sound, and is a direct drive unit. The second sound-emitting unit is used to vibrate and emit sound under the action of a modulation signal, and is an ultrasonic modulation sound-emitting unit. The area occupied by the first sound-emitting unit in the device layer is larger than the area occupied by each second sound-emitting unit in the device layer, and the sound frequency of the first sound-emitting unit is larger than the sound frequency of the second sound-emitting unit, so that the first sound-emitting unit has a better response and a higher sound pressure level in high-frequency conditions; and the second sound-emitting unit has a better response and a higher sound pressure level in low-frequency conditions. The embodiment of the present application integrates the first sound-emitting unit and the second sound-emitting unit into the same sound-emitting device, so that the entire sound-emitting device has a higher sound pressure level at both high and low frequencies, that is, the sound-emitting device of the embodiment of the present application can achieve a high sound pressure level response in the full frequency band. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 One of the structural schematic diagrams of a sound-generating device provided in an embodiment of the present application;

[0019] Figure 2 A second structural schematic diagram of a sound-generating device provided in an embodiment of the present application;

[0020] Figure 3 One of the structural schematic diagrams of a first sound-emitting unit provided in an embodiment of the present application;

[0021] Figure 4 A second structural diagram of a first sound-emitting unit provided in an embodiment of the present application;

[0022] Figure 5 A third structural diagram of a first sound-emitting unit provided in an embodiment of the present application;

[0023] Figure 6 A fourth structural diagram of a first sound-emitting unit provided in an embodiment of the present application;

[0024] Figure 7 A fifth structural diagram of a first sound-emitting unit provided in an embodiment of the present application;

[0025] Figure 8 A sixth structural diagram of a first sound-emitting unit provided in an embodiment of the present application;

[0026] Fig. 9 A seventh structural diagram of a first sound-emitting unit provided in an embodiment of the present application;

[0027] Fig.10 An eighth structural diagram of a first sound-emitting unit provided in an embodiment of the present application;

[0028] Fig.11 A flow chart of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0029] Fig.12 One of the state diagrams of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0030] Fig.13 A second state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0031] Fig.14 A third state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0032] Fig.15 A fourth state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0033] Fig.16 A fifth state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0034] Fig.17 A sixth state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0035] Fig.18 A seventh state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0036] Fig.19 An eighth state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0037] Fig. 20 A ninth state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0038] Fig.21 A tenth state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0039] Fig. 22 The eleventh state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0040] Fig.23 A twelve-state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0041] Fig.24 The thirteenth state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application;

[0042] Fig.25 This is a fourteenth state diagram of a method for preparing a sound-generating device provided in an embodiment of the present application.

[0043] Icons: 100-sound-generating device; 110-substrate; 111-first back cavity; 112-large cavity; 113-strip cavity; 114-second back cavity; 120-device layer; 121-first sound-generating unit; 122-second sound-generating unit; 123-first cantilever beam structure; 124-second cantilever beam structure; 125-bottom electrode; 126-piezoelectric layer; 127-top electrode; 210-first substrate; 211-first groove; 212-second groove; 213-sacrificial material; 220-second substrate; 230-silicon on insulator; 231-first cavity; 232-second cavity; 240-substrate; 251-third substrate; 252-fourth substrate; 253-strip groove. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0045] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0046] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0047] Piezoelectric MEMS sound-generating devices use piezoelectric drive instead of coil / magnet drive. Based on the piezoelectric principle, they do not generate electromagnetic radiation. The electrical impedance depends entirely on the capacitance between the two electrodes of the MEMS sound-generating device. The electrical impedance of the pure capacitor means that no DC current will pass through during operation. Polarization and transfer of charges only occur when the electric field changes. This characteristic makes its power consumption lower than that of electromagnetic speakers.

[0048] The present application embodiment provides a sound-generating device, such as Figure 1 and Figure 2 As shown, it includes a substrate and a device layer arranged on the substrate, in which a first sound unit and a plurality of second sound units surrounded by the first sound unit are arranged, the first sound unit is driven to vibrate and make sound, and the second sound unit is used to vibrate and make sound under the action of a modulation signal, the area occupied by the first sound unit in the device layer is larger than the area occupied by each second sound unit in the device layer, and the sound frequency of the first sound unit is larger than the sound frequency of the second sound unit.

[0049] The sound-emitting device 100 provided in the embodiment of the present application utilizes the piezoelectric effect to generate vibrations to disturb the air and generate sound. Specifically, the sound-emitting device 100 in the embodiment of the present application includes a substrate 110 and a device layer 120 disposed on the substrate 110, wherein the device layer 120 is provided with a first sound-emitting unit 121 and a second sound-emitting unit 122, wherein the first sound-emitting unit 121 is driven to vibrate and generate sound, and is a direct drive unit, the first sound-emitting unit 121 occupies a larger area in the device layer 120, and the sound emission frequency of the first sound-emitting unit 121 is larger, so that the first sound-emitting unit 121 has a better response in high-frequency conditions and a higher sound pressure level; the second sound-emitting unit 122 is used to modulate the signal. The second sound unit 122 vibrates and makes sound under the action, and occupies a smaller area in the device layer 120, and is an ultrasonically modulated sound unit. The sound frequency of the second sound unit 122 is smaller, so that the second sound unit 122 has a better response in the low frequency case and a higher sound pressure level. The embodiment of the present application integrates the first sound unit 121 and the second sound unit 122 into the same sound device 100, so that the entire sound device 100 has a higher sound pressure level at both high and low frequencies, that is, the sound device 100 of the embodiment of the present application can achieve a high sound pressure level response in the full frequency band.

[0050] Among them, the second sound unit 122 occupies a smaller area in the device layer 120, so a plurality of second sound units 122 are provided, and the plurality of second sound units 122 are arranged around the periphery of the first sound unit 121, so that the first sound unit 121 and the second sound unit 122 can be arranged more concentratedly, so that the external sound generation is more concentrated.

[0051] In practical applications, the device layer 120 is used as a layer for generating vibrations, including Figure 1 The bottom electrode 125, the piezoelectric layer 126 and the top electrode 127 are shown, wherein the top electrode 127 and the bottom electrode 125 are respectively connected to external signals to form a voltage difference on both sides of the piezoelectric layer 126, so that the piezoelectric layer 126 vibrates under the piezoelectric effect.

[0052] The sound-emitting device 100 provided in the present application includes a substrate 110 and a device layer 120 arranged on the substrate 110. In the device layer 120, a first sound-emitting unit 121 and a plurality of second sound-emitting units 122 surrounded by the outer periphery of the first sound-emitting unit 121 are arranged. The first sound-emitting unit 121 is driven to vibrate and emit sound, and is a direct drive unit. The second sound-emitting unit 122 is used to vibrate and emit sound under the action of a modulation signal, and is an ultrasonic modulation sound-emitting unit. The area occupied by the first sound-emitting unit 121 in the device layer 120 is larger than the area occupied by each second sound-emitting unit 122 in the device layer 120, and the sound frequency of the first sound-emitting unit 121 is larger than the sound frequency of the second sound-emitting unit 122, so that the first sound-emitting unit 121 has a better response and a higher sound pressure level in high-frequency conditions; and the second sound-emitting unit 122 has a better response and a higher sound pressure level in low-frequency conditions. The embodiment of the present application integrates the first sound unit 121 and the second sound unit 122 into the same sound device 100, so that the entire sound device 100 has a higher sound pressure level at both high and low frequencies, that is, the sound device 100 of the embodiment of the present application can achieve a high sound pressure level response in the full frequency band.

[0053] Optional, such as Figure 1 As shown, a first back cavity 111 is formed in the substrate 110 corresponding to the first sound emitting unit 121 , and the first back cavity 111 includes a large cavity 112 close to the device layer 120 and a plurality of strip-shaped cavities 113 connected to the large cavity 112 away from the device layer 120 .

[0054] The first sound unit 121 and the second sound unit 122 need to vibrate up and down along the hierarchical direction during the sound generation process. Thus, back cavities are formed in the substrate 110 corresponding to the first sound unit 121 and the second sound unit 122, respectively. Figure 1As shown, in actual applications, since the area occupied by the first sound unit 121 in the device layer 120 is larger than the area occupied by the second sound unit 122 in the device layer 120, the cross-sectional area of ​​the back cavity corresponding to the first sound unit 121 is larger than the cross-sectional area of ​​the back cavity corresponding to the second sound unit 122, that is, the cross-sectional area of ​​the first back cavity 111 is larger than the cross-sectional area of ​​the second back cavity 114.

[0055] During the preparation of the sound-generating device 100, the first back cavity 111 and the second back cavity 114 are usually formed by etching the lower surface of the substrate 110. The first back cavity 111 has a larger etching rate due to its larger cross-sectional area, while the second back cavity 114 has a smaller etching rate, so that the first back cavity 111 and the second back cavity 114 cannot be formed at the same time, and either the second back cavity 114 cannot be formed or the device layer 120 is damaged.

[0056] In the embodiment of the present application, the first back cavity 111 is divided into a large cavity 112 and a plurality of strip-shaped cavities 113, wherein the large cavity 112 is provided with a pre-set sacrificial material 213; the second back cavity 114 is divided into two parts, one is a first part having the same height as the large cavity 112, which is used to fill the sacrificial material 213; the other part is a second part having the same height as the strip-shaped cavity 113. When etching, only the strip-shaped cavity 113 and the second part need to be etched. At this time, the cross-sectional area of ​​the strip-shaped cavity 113 and the second part are equivalent, and the height is the same, and the sacrificial material 213 can also be used as an etching stop layer, so that the strip-shaped cavity 113 and the second part are etched at the same time, and finally the large cavity 112 and the first part are released by releasing the sacrificial material 213, thereby avoiding the problem that the first back cavity 111 and the second back cavity 114 cannot be formed at the same time.

[0057] In one possible implementation of the embodiment of the present application, Figures 3 to 10 As shown, the first sound unit 121 includes a plurality of first cantilever beam structures 123 , which are sequentially arranged along the edge of the first back cavity 111 , and the first cantilever beam structure 123 includes a fixed end arranged on the substrate 110 and a free end extending toward the first back cavity 111 .

[0058] According to the foregoing, the first sound unit 121 occupies a relatively large area in the device layer 120. In order to realize direct driven sound, the first sound unit 121 in the embodiment of the present application includes a plurality of first cantilever beam structures 123. The first cantilever beam structure 123 vibrates under the action of the driving signal. Specifically, the first cantilever beam structure 123 includes a fixed end connected to the substrate 110 and a free end located in the first back cavity 111. When driven to vibrate, the vibration of the free end drives the air in the first back cavity 111 to vibrate and realize sound.

[0059] The specific shape of the first sound unit 121 is not limited in the present embodiment, and can be, for example, as follows: Figure 3 The circle shown, Figure 4 The square shown, Figure 5 The square shown or Figure 6 The hexagonal shape shown in the figure, those skilled in the art can also set the specific structure of the first sound unit 121 and the number of the first cantilever beams according to actual conditions.

[0060] Optional, such as Figures 3 to 10 As shown, the multiple free ends are close to each other and gaps are formed between the multiple first cantilever beams; or, the multiple free ends are close to each other and gaps are formed between the multiple first cantilever beams.

[0061] Among them, Figures 3 to 6 As shown, gaps are formed between the plurality of first cantilever beams; Figures 7 to 10 As shown, gaps are formed between the plurality of first cantilever beams.

[0062] In one implementable manner of the embodiment of the present application, a second back cavity 114 is formed in the substrate 110 corresponding to each second sound emitting unit 122 , and each second sound emitting unit 122 includes a second cantilever beam structure 124 .

[0063] The second sound unit 122 occupies a relatively small area on the device layer 120 . Therefore, the cross-sectional area of ​​the second back cavity 114 is relatively small. Sound generation can be achieved by providing a second cantilever beam structure 124 .

[0064] Optionally, a plurality of second sound emitting units 122 are arranged in a circle on the outer circumference of the second sound emitting unit 122 and are arranged in multiple layers.

[0065] The plurality of second sound generating units 122 are arranged in a circle on the outer periphery of the second sound generating unit 122, making the structure of the sound generating device 100 more compact, thereby reducing the volume of the sound generating device 100. In addition, the structure of the sound generating device 100 is more compact, making the sound generating part of the sound generating device 100 more concentrated.

[0066] The present application also discloses a method for preparing a sound-generating device 100, which is used to prepare the sound-generating device 100. Fig.11 As shown, including:

[0067] S10: Fig.12 and Fig.13 As shown, a substrate 110 is provided, and a device layer 120 is formed on the substrate 110;

[0068] In practical applications, the device layer 120 is used as a layer for generating vibrations, including Figure 1The bottom electrode 125, the piezoelectric layer 126 and the top electrode 127 are shown, wherein the top electrode 127 and the bottom electrode 125 are respectively connected to external signals to form a voltage difference on both sides of the piezoelectric layer 126, so that the piezoelectric layer 126 vibrates under the piezoelectric effect.

[0069] The materials of the top electrode 127 and the bottom electrode 125 may be platinum, gold, molybdenum, titanium, etc.; the material of the piezoelectric layer 126 may be aluminum nitride, lead zirconate titanate, potassium sodium niobate, etc.

[0070] S20: Fig.13 As shown, the device layer 120 is etched to form a first sound unit 121 and a plurality of second sound units 122 in the device layer 120, and the plurality of second sound units 122 are surrounded by the periphery of the first sound unit 121, wherein the area occupied by the first sound unit 121 in the device layer 120 is larger than the area occupied by each second sound unit 122 in the device layer 120, and the sound frequency of the first sound unit 121 is larger than the sound frequency of the second sound unit 122;

[0071] The specific structures of the first sound emitting unit 121 and the second sound emitting unit 122 are described in detail in the content of the sound emitting device 100 and will not be repeated here.

[0072] S30: Fig.14 As shown, a first back cavity 111 corresponding to the first sound unit 121 and a plurality of second back cavities 114 corresponding to the second sound unit 122 are formed by etching the lower surface of the substrate 110 .

[0073] The first back cavity 111 provides a vibration space for the first sound unit 121 , and the second back cavity 114 provides a vibration space for the second sound unit 122 .

[0074] The sound-emitting device 100 prepared by the method for preparing the sound-emitting device 100 provided in the embodiment of the present application integrates corresponding sound-emitting units with higher sound pressure levels at different frequencies into the same sound-emitting device 100, so that the sound-emitting device 100 can achieve high sound pressure level response in the full frequency band.

[0075] When the first back cavity 111 includes a large cavity 112 close to the device layer 120 and a plurality of strip-shaped cavities 113 connected to the large cavity 112 away from the device layer 120, a sacrificial material 213 or the large cavity 112 needs to be pre-embedded in the substrate 110. The substrate 110 can be formed in the following ways:

[0076] The first method is to form the sacrificial material 213 by bonding:

[0077] In one achievable manner of the embodiment of the present application, providing the substrate 110 includes:

[0078] S11: Fig.15 As shown, a first substrate 210 is provided, and a first groove 211 and a plurality of second grooves 212 are formed on the upper surface of the first substrate 210, wherein the plurality of second grooves 212 surround the outer periphery of the first groove 211, and the cross section of the first groove 211 is larger than the cross section of each second groove 212;

[0079] S12: Fig.16 As shown, a sacrificial material 213 is filled in the first groove 211 and the plurality of second grooves 212 to form a first semi-finished product;

[0080] S13: Fig.17 and Fig.18 As shown, a second substrate 220 is provided and bonded to the first semi-finished product, wherein the bonding surface of the first semi-finished product is the upper surface of the sacrificial material 213;

[0081] S14: Fig.18 As shown, the second substrate 220 is thinned to form the substrate 110 .

[0082] The second method uses the buried cavity type silicon-on-insulator 230 finished product:

[0083] Optional, such as Fig.19 As shown, the substrate 110 includes a buried cavity type silicon-on-insulator 230, and a first cavity 231 and a plurality of second cavities 232 are pre-buried on the upper surface of the insulating layer of the silicon-on-insulator 230. The plurality of second cavities 232 are surrounded by the outer periphery of the first cavity 231, and the cross-section of the first cavity 231 is larger than the cross-section of each second cavity 232.

[0084] Among them, the silicon on insulator 230 includes an insulating layer and a silicon layer arranged on the insulating layer. In the embodiment of the present application, a first cavity 231 and a plurality of second cavities 232 are pre-buried on the upper surface of the insulating layer. The first cavity 231 serves as the large cavity 112 of the first back cavity 111, and the second cavity 232 serves as the first part in the second back cavity 114, and the first part has the same height as the large cavity 112.

[0085] When using the finished silicon on insulator 230, in order to position the first cavity 231 and the second cavity 232, a back alignment mark can be formed by etching on the lower surface of the silicon on insulator, such as Fig.19 shown.

[0086] By using the silicon-on-insulator 230 product, the preparation process of the sound-generating device 100 can be simplified.

[0087] The third method is to directly prepare the substrate 110:

[0088] In one achievable manner of the embodiment of the present application, providing the substrate 110 includes:

[0089] S11': Fig. 20 As shown, a substrate 240 is provided, and a first groove 211 and a plurality of second grooves 212 are etched on the upper surface of the substrate 240, wherein the plurality of second grooves 212 surround the outer periphery of the first groove 211, and the cross section of the first groove 211 is larger than the cross section of each second groove 212;

[0090] The first groove 211 serves as the large cavity 112 of the first back cavity 111 , and the second groove 212 serves as the first part of the second back cavity 114 .

[0091] S12': Fig.21 As shown, a sacrificial material 213 is filled in the first groove 211 and the plurality of second grooves 212 to form the substrate 110 .

[0092] In practical applications, a polysilicon or silicon nitride layer is usually provided on the substrate 240 filled with the sacrificial material 213 as a seed layer. Fig. 22 shown.

[0093] When the substrate 110 uses the pre-buried sacrificial material 213 or the large cavity 112, the first back cavity 111 corresponding to the first sound unit 121 and the plurality of second back cavities 114 corresponding to the second sound unit 122 are formed by etching the lower surface of the substrate 110, including:

[0094] S31: etching the lower surface of the substrate 110 to form a plurality of strip-shaped cavities 113, wherein the plurality of strip-shaped cavities 113 include a plurality of cavities corresponding to the first sound-emitting units 121 and one cavity corresponding to each second sound-emitting unit;

[0095] At this time, the cross-sectional area and depth of the strip-shaped cavity 113 are the same, so the etching efficiency is the same, and the sacrificial layer serves as an etching barrier layer to avoid the problem caused by the inability to complete the etching at the same time.

[0096] S32: releasing the sacrificial material 213 to form a large cavity 112 or a small cavity, partially connecting the strip-shaped cavity 113 with the large cavity 112 or the first cavity 231 to form a first back cavity 111 , and partially connecting the strip-shaped cavity 113 with the small cavity to form a second back cavity 114 .

[0097] By utilizing etching and releasing, the difficulty of back cavity etching of the sound-generating device 100 is reduced, and the processing yield of the sound-generating device is improved.

[0098] In practical applications, there is another method for forming the substrate 110, such as Fig.23 As shown, a third substrate 251 is provided, and a groove is formed on the third substrate 251 and filled with a sacrificial material 213; Fig.24As shown, a fourth substrate 252 is provided and a plurality of strip grooves 253 are formed by etching on the fourth substrate 252; finally, as shown Fig.25 As shown, the substrate 110 can be obtained by bonding the third substrate 251 and the fourth substrate 252 .

[0099] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A sound-generating device, characterized in that: It includes a substrate and a device layer arranged on the substrate, in which a first sound unit and a plurality of second sound units surrounded by the first sound unit are arranged, the first sound unit is driven to vibrate and make sound, and the second sound unit is used to vibrate and make sound under the action of a modulation signal, the area occupied by the first sound unit in the device layer is larger than the area occupied by each of the second sound units in the device layer, and the sound frequency of the first sound unit is larger than the sound frequency of the second sound unit.

2. The sound generating device according to claim 1, characterized in that: A first back cavity is formed in the substrate corresponding to the first sound-emitting unit, and the first back cavity includes a large cavity close to the device layer and a plurality of strip-shaped cavities connected to a side of the large cavity away from the device layer.

3. The sound-generating device according to claim 2, characterized in that: The first sound-emitting unit includes a plurality of first cantilever beam structures, which are sequentially arranged along the edge of the first back cavity. The first cantilever beam structure includes a fixed end arranged on the substrate and a free end extending toward the first back cavity.

4. The sound-generating device according to claim 3, characterized in that: The plurality of free ends are close to each other and gaps are formed between the plurality of first cantilever beams; or, the plurality of free ends are close to each other and gaps are formed between the plurality of first cantilever beams.

5. The sound generating device according to claim 1, characterized in that: A second back cavity is formed in the substrate corresponding to each of the second sound emitting units, and each of the second sound emitting units includes a second cantilever beam structure.

6. The sound generating device according to claim 1, characterized in that: The plurality of second sound emitting units are arranged in a circle on the outer circumference of the second sound emitting unit and are arranged in multiple layers.

7. A method for preparing a sound-generating device, used for preparing the sound-generating device according to any one of claims 1 to 6, characterized in that: include: Providing a substrate, and forming a device layer on the substrate; Etching the device layer to form a first sound emitting unit and a plurality of second sound emitting units in the device layer, wherein the plurality of second sound emitting units are surrounded by the periphery of the first sound emitting unit, wherein an area occupied by the first sound emitting unit in the device layer is larger than an area occupied by each of the second sound emitting units in the device layer, and a sound frequency of the first sound emitting unit is larger than a sound frequency of the second sound emitting unit; A first back cavity corresponding to the first sound unit and a plurality of second back cavities corresponding to the second sound unit are formed by etching the lower surface of the substrate.

8. The method for preparing a sound-generating device according to claim 7, characterized in that: The providing of the substrate comprises: Providing a first substrate, and opening a first groove and a plurality of second grooves on the upper surface of the first substrate, wherein the plurality of second grooves are surrounded by the outer periphery of the first groove, and a cross section of the first groove is larger than a cross section of each of the second grooves; Filling the first groove and the plurality of the second grooves with a sacrificial material to form a first semi-finished product; Providing a second substrate and bonding it to the first semi-finished product, wherein the bonding surface of the first semi-finished product is the upper surface of the sacrificial material; The second substrate is thinned to form a backing.

9. The method for preparing a sound-generating device according to claim 7, characterized in that: The substrate includes a buried cavity type silicon-on-insulator, wherein a first cavity and a plurality of second cavities are pre-buried on an upper surface of an insulating layer of the silicon-on-insulator, the plurality of second cavities are enclosed around the outer periphery of the first cavity, and a cross-section of the first cavity is larger than a cross-section of each of the second cavities.

10. The method for preparing a sound-generating device according to claim 7, characterized in that: The providing of the substrate comprises: Providing a substrate, and etching a first groove and a plurality of second grooves on an upper surface of the substrate, wherein the plurality of second grooves are surrounded by an outer periphery of the first groove, and a cross section of the first groove is larger than a cross section of each of the second grooves; A sacrificial material is filled in the first groove and the plurality of second grooves to form a substrate.

11. The method for preparing a sound-generating device according to any one of claims 8 to 10, characterized in that: The first back cavity corresponding to the first sound unit and a plurality of second back cavities corresponding to the second sound unit formed by etching the lower surface of the substrate include: A plurality of strip-shaped cavities are formed by etching the lower surface of the substrate, wherein the plurality of strip-shaped cavities include a plurality of cavities corresponding to the first sound-emitting units and one corresponding to each of the second sound-emitting units; The sacrificial material is released to form a large cavity or a small cavity, part of the strip-shaped cavity is connected with the large cavity or the first cavity to form a first back cavity, and part of the strip-shaped cavity is connected with the small cavity in a one-to-one correspondence to form a second back cavity.

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