MEMS loudspeaker, manufacturing method thereof and electronic equipment

Abstract

The invention relates to the field of semiconductor devices, and provides an MEMS loudspeaker, a manufacturing method thereof and electronic equipment. The MEMS loudspeaker comprises a substrate and a vibrating diaphragm located on the upper side of the substrate in the thickness direction, a sound cavity is formed between the vibrating diaphragm and the upper portion of the substrate in the thickness direction, a sound hole is formed in the lower side of the substrate in the thickness direction, and the sound cavity is communicated with the sound hole. And the size of at least one part of the sound cavity in the thickness direction in the horizontal direction is larger than the size of at least one part of the sound hole in the thickness direction in the horizontal direction. Therefore, the sound cavity and the sound hole are respectively formed at the upper side and the lower side of the substrate, and the substrate widths at the left side and the right side of the sound cavity are narrower than the substrate widths at the left side and the right side of the sound hole, so that the effective working area of the vibrating diaphragm is ensured, the strength of the substrate is enhanced, the conditions of wafer fragments or chip breakage are avoided, the performance of the MEMS loudspeaker can be improved, and the manufacturing cost of the MEMS loudspeaker is reduced. And the production cost can also be reduced.

Description

Technical Field

[0001] This application relates to the field of semiconductor devices, and particularly to a MEMS speaker, a manufacturing method thereof, and an electronic device. Background Art

[0002] With the development of semiconductor technology, devices based on microelectromechanical system (MEMS) technology have been widely used in electronic products such as smart phones due to their small size and good performance. Among them, a speaker based on MEMS technology (hereinafter referred to as "MEMS speaker") can be manufactured by semiconductor processes. Compared with traditional speakers, MEMS speakers have the advantages of small size, good performance, and low cost, and are easy to mass produce, and are expected to be widely used in small electronic products such as mobile phones and earphones.

[0003] An index for measuring the performance of a speaker is the sound pressure level (SPL for short). The larger the sound pressure level, the greater the sound intensity, and the louder the sound that can be heard by the human ear.

[0004] A MEMS speaker includes a substrate, a diaphragm attached to the substrate, and acoustic cavities and sound holes located on both sides of the diaphragm. When the MEMS speaker works, the diaphragm vibrates under the drive of, for example, electrostatic force, and the air in the acoustic cavity will vibrate accordingly and propagate through the sound holes into the space to generate sound. The size of the sound pressure level of a MEMS speaker is related to the effective working area of the diaphragm. A sufficiently large effective working area can achieve a higher sound pressure level, and the effective working area of the diaphragm is related to the size of the acoustic cavity. Within a certain range, the larger the acoustic cavity, the larger the effective working area of the diaphragm, and the greater the sound pressure level.

[0005] This section aims to provide background or context for the embodiments of the present application stated in the claims. The description herein is not admitted to be prior art merely because it is included in this section. Summary of the Invention

[0006] The inventors found that in traditional MEMS speakers, the process of etching the substrate from the back to form acoustic cavities and sound holes is adopted. The larger the acoustic cavity, the thinner the remaining part of the substrate after etching (i.e., the supporting part at the edge of the chip), and it is easy to occur the situation of wafer fragmentation or chip breakage. To avoid situations such as wafer breakage, one solution is to reduce the area of the acoustic cavity while keeping the size of the chip unchanged, however, this will lead to a decrease in the performance of the speaker. Another solution is to increase the chip size while keeping the area of the acoustic cavity unchanged, however, this will lead to a decrease in the number of chips per unit area, reducing the utilization rate of the wafer, reducing the yield, and increasing the cost.

[0007] To solve at least one of the above problems or other similar problems, an embodiment of the present application provides a MEMS speaker, a manufacturing method thereof, and an electronic device.

[0008] According to a first aspect of the embodiments of the present application, there is provided a MEMS speaker, the MEMS speaker including a substrate and a diaphragm located on the upper side in the thickness direction of the substrate, wherein,

[0009] An acoustic cavity is formed between the diaphragm and the upper part in the thickness direction of the substrate,

[0010] Sound holes are formed on the lower side in the thickness direction of the substrate,

[0011] The acoustic cavity is communicated with the sound holes, and at least a part of the acoustic cavity in the horizontal direction in the thickness direction is larger than at least a part of the sound holes in the horizontal direction in the thickness direction.

[0012] According to a second aspect of the embodiments of the present application, there is provided a manufacturing method of a MEMS speaker, the manufacturing method including:

[0013] Forming a diaphragm on the upper side in the thickness direction of the substrate,

[0014] Forming sound holes on the lower side in the thickness direction of the substrate,

[0015] Forming an acoustic cavity between the diaphragm and the upper part in the thickness direction of the substrate, wherein the acoustic cavity is communicated with the sound holes, and at least a part of the acoustic cavity in the horizontal direction in the thickness direction is larger than at least a part of the sound holes in the horizontal direction in the thickness direction.

[0016] According to a third aspect of the embodiments of the present application, there is provided an electronic device, the electronic device including the MEMS speaker described in the embodiments of the first aspect.

[0017] One of the beneficial effects of the embodiments of the present application is that by forming an acoustic cavity and sound holes on the upper and lower sides of the substrate respectively, the width of the substrate on both sides of the acoustic cavity is narrower than the width of the substrate on both sides of the sound holes, so as to enhance the strength of the substrate while ensuring the effective working area of the diaphragm, avoiding the occurrence of wafer fragmentation or chip breakage, thereby improving the performance of the MEMS speaker and reducing the production cost. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0019] Figure 1 It is a top view schematic diagram of the MEMS speaker in the embodiment of the present application.

[0020] Figure 2 is Figure 1 A cross-sectional view of the MEMS speaker shown along the A-A' direction.

[0021] Figure 3 is Figure 1 A cross-sectional view of another embodiment of the MEMS speaker shown along the A-A' direction.

[0022] Figure 4 is Figure 1 A cross-sectional view of another embodiment of the MEMS speaker shown along the A-A' direction.

[0023] Figure 5 is Figure 1 A cross-sectional view of another embodiment of the MEMS speaker shown along the A-A' direction.

[0024] Figure 6 It is a cross-sectional view of another embodiment of the MEMS speaker in the embodiment of the present application.

[0025] Figure 7 It is a cross-sectional view of another embodiment of the MEMS speaker in the embodiment of the present application.

[0026] Figure 8 It is a cross-sectional view of another embodiment of the MEMS speaker in the embodiment of the present application.

[0027] Figure 9 It is a cross-sectional view of another embodiment of the MEMS speaker in the embodiment of the present application.

[0028] Figure 10 It is a schematic diagram of the manufacturing method of the MEMS speaker in the embodiment of the present application.

[0029] Figure 11 is Figure 2 A schematic diagram of the manufacturing process of the MEMS speaker shown.

[0030] Figure 12 is Figure 2Another schematic diagram of the manufacturing process of the MEMS speaker shown.

[0031] Figure 13 is Figure 2 Another schematic diagram of the manufacturing process of the MEMS speaker shown.

[0032] Figure 14 is Figure 6 A schematic diagram of the manufacturing process of the MEMS speaker shown.

[0033] Figure 15 is Figure 6 Another schematic diagram of the manufacturing process of the MEMS speaker shown.

[0034] Figure 16 is Figure 6 Another schematic diagram of the manufacturing process of the MEMS speaker shown.

[0035] Figure 17 is Figure 8 A schematic diagram of the manufacturing process of the MEMS speaker shown.

[0036] Figure 18 is Figure 8 Another schematic diagram of the manufacturing process of the MEMS speaker shown.

[0037] Figure 19 is Figure 8 Another schematic diagram of the manufacturing process of the MEMS speaker shown.

[0038] Figure 20 is Figure 8 Another schematic diagram of the manufacturing process of the MEMS speaker shown. Detailed implementation manners

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer and more understandable, the following further describes the embodiments of the present application in detail with reference to the accompanying drawings. Herein, the illustrative embodiments of the present application and their descriptions are used to explain the present application, but do not limit the present application.

[0040] In the embodiments of the present application, terms such as "first", "second", "upper", and "lower" are used to distinguish different elements in terms of appellation, but do not indicate the spatial arrangement or time sequence of these elements, and these elements should not be limited by these terms. The term "and / or" includes any one and all combinations of one or more of the associated listed terms. Terms such as "include", "comprise", and "have" mean the presence of the stated features, elements, components, or assemblies, but do not exclude the presence or addition of one or more other features, elements, components, or assemblies.

[0041] In the embodiments of the present application, singular forms such as "a" and "the" include plural forms and should be broadly understood as "a kind" or "a class" rather than being limited to the meaning of "one"; in addition, the term "said" should be understood to include both singular and plural forms unless the context clearly indicates otherwise. In addition, the term "according to" should be understood as "at least partially according to...", and the term "based on" should be understood as "at least partially based on...", unless the context clearly indicates otherwise.

[0042] The embodiments of the present application will be described below with reference to the accompanying drawings.

[0043] The embodiments of the present application provide a MEMS speaker. Figure 1 is a top view schematic diagram of the MEMS speaker of the embodiments of the present application, Figure 2 is Figure 1 a sectional view along the A-A' direction of an embodiment of the MEMS speaker shown in Figure 3 is Figure 1 a sectional view along the A-A' direction of another embodiment of the MEMS speaker shown in Figure 4 is Figure 1 a sectional view along the A-A' direction of another embodiment of the MEMS speaker shown in Figure 5 is Figure 1 a sectional view along the A-A' direction of another embodiment of the MEMS speaker shown in

[0044] As Figure 1 and Figure 2 shown, the MEMS speaker 1 includes a substrate 30 and a diaphragm 10. The diaphragm 10 is located on the upper side in the thickness direction z of the substrate 30. An acoustic cavity 20 is formed between the diaphragm 10 and the upper part in the thickness direction z of the substrate 30. An acoustic hole 40 is formed on the lower side in the thickness direction z of the substrate 30. The acoustic cavity 20 is communicated with the acoustic hole 40. In the thickness direction z, the projection of the diaphragm 10 overlaps with the projection of the acoustic cavity 20. The overlapping area of the diaphragm 10 and the acoustic cavity 20 is called the "effective working area of the diaphragm 10". The larger the projected area of the acoustic cavity 20, the larger the effective working area of the diaphragm 10, and the higher the sound pressure level of the MEMS speaker 1.

[0045] In addition, in Figure 1 the acoustic cavity 20 and the acoustic hole 40 are exemplified by a rectangular dotted line frame, but the embodiments of the present application are not limited thereto. The shapes of the acoustic cavity 20 and the acoustic hole 40 can also be circular or other shapes.

[0046] In the embodiments of the present application, for the convenience of description, the thickness direction of the substrate 30 is denoted as the "z direction", the width direction of the substrate 30 is denoted as the "x direction", and the length direction of the substrate 30 is denoted as the "y direction". The x direction, y direction, and z direction are perpendicular to each other. Additionally, when there is no ambiguity, sometimes the "z direction" is also referred to as the "vertical direction", and the x direction and y direction are referred to as the "horizontal direction". Further, for the convenience of description, for the thickness direction, the direction from the substrate 30 to the diaphragm 10 is called "up", the direction from the diaphragm 10 to the substrate 30 is called "down", the surface located in the "up" direction is called the "upper surface", and the surface located in the "down" direction is called the "lower surface", except for special instructions. In addition, those skilled in the art should understand that the "up" and "down" described in the embodiments of the present application are only used to distinguish different elements in terms of nomenclature, but do not represent the spatial arrangement of these elements.

[0047] In some embodiments, the substrate 30 can be formed of a semiconductor material, or can also be formed by a composite of multiple layers of materials, and the embodiments of the present application do not limit this. For example, the substrate 30 can be formed of single crystal silicon, for example, formed of high-resistance silicon material, and the resistivity of the silicon material is, for example, greater than 1000 Ω·cm, for example, the resistivity > 5000 Ω·cm, and the embodiments of the present application do not limit this. For example, the substrate 30 can also be formed of materials such as lithium niobate, lithium tantalate, silicon carbide (SiC), sapphire, quartz, etc. Additionally, the substrate 30 can also be formed of semiconductor materials such as silicon dioxide, silicon nitride, polysilicon, amorphous silicon, etc., and the embodiments of the present application do not limit this.

[0048] In the embodiments of the present application, MEMS speakers can be classified into piezoelectric, electromagnetic, electrostatic, etc. according to different driving methods of the diaphragm. The MEMS speaker 1 in the embodiments of the present application can be any one of piezoelectric, electromagnetic, and electrostatic, and the embodiments of the present application do not limit this.

[0049] For example, as Figure 3 shown, the diaphragm 10 can include an electrode layer 12 and a piezoelectric layer 11. For example, the diaphragm 10 includes three electrode layers 12 and two piezoelectric layers 11 stacked alternately; additionally, as Figure 4 shown, the diaphragm 10 can also include a structural layer 13. For example, the diaphragm 10 includes a structural layer 13, an electrode layer 12, a piezoelectric layer 11, and an electrode layer 12 stacked in sequence from bottom to top. Additionally, the number of piezoelectric layers 11, electrode layers 12, and structural layers 13 included in the diaphragm 10 is arbitrary, and the embodiments of the present application do not limit this.

[0050] In the above example, the piezoelectric layer 11 can be formed of a piezoelectric thin film. For example, the piezoelectric thin film can be formed of a single-crystal piezoelectric material, which can be selected according to actual needs or performance requirements. The embodiments of the present application do not limit the specific material.

[0051] In addition, the material for forming the electrode layer 12 can be a metal. For example, elemental metals such as molybdenum (Mo), aluminum (Al), copper (Cu), platinum (Pt), tantalum (Ta), tungsten (W), palladium (Pd), ruthenium (Ru), gold (Au), titanium (Ti), chromium (Cr), etc., or their alloys or their composite laminates; the material of the electrode layer 12 can also be doped polysilicon, and the doping elements can be boron (B), phosphorus (P), arsenic (As), etc., and the doping concentration is, for example, 10 19 cm -3 Above, within a certain range, the higher the doping concentration, the lower the sheet resistance of the electrode made of polysilicon and the lower the electrical loss. The embodiments of the present application do not limit this.

[0052] In addition, the material for forming the structural layer 13 can be silicon, silicon dioxide, fluorine-doped silicon dioxide, silicon nitride, silicon oxynitride, aluminum nitride, aluminum oxide, titanium oxide, tantalum pentoxide, etc., and can be a single layer or a combination of multiple different dielectric materials. The embodiments of the present application do not limit this.

[0053] In the embodiments of the present application, as Figure 2 shown, at least a part of the width of the substrate 30 located outside the acoustic cavity 20 is smaller than at least a part of the width of the substrate 30 located outside the sound hole 40. In addition, it can also be said that the width of the substrate 30 outside the acoustic cavity 20 is smaller than the width of the substrate 30 outside the sound hole 40. Or, it can also be said that the area of the projection of the acoustic cavity 20 in the z direction is larger than the area of the projection of the sound hole 40 in the z direction. Or, it can also be said that at least a part of the size of the acoustic cavity 20 in the thickness direction in the horizontal direction is larger than at least a part of the size of the sound hole 40 in the thickness direction in the horizontal direction. The width of the substrate 30 described in the embodiments of the present application or the sizes of the acoustic cavity 20 and the sound hole 40 in the horizontal direction can be the width or size in a certain cross section in the horizontal direction, or the overall width or size, or the average width or average size in the horizontal direction, as long as the same type of width or size is compared. The embodiments of the present application do not limit this.

[0054] Thus, while ensuring a relatively large effective working area of the diaphragm 10, the strength of the substrate 30 is enhanced, and the situation of wafer fragmentation or chip breakage is avoided, so that both the performance of the MEMS speaker can be improved and the production cost can be reduced.

[0055] In the embodiments of the present application, the acoustic cavity 20 can be formed by forming a depression on the substrate 30, or can be formed by the bulging of the diaphragm 10, which will be described separately below.

[0056] In some embodiments, as Figure 2 and Figure 5 shown, a recess 30a is formed in the upper part of the substrate 30, and the diaphragm 10 and the recess 30a form a sound cavity 20.

[0057] As Figure 2 shown, the side wall surface 20b of the recess 30a can be a curved surface. As Figure 5 shown, the side wall surface 20b of the recess 30a can also be an inclined surface, that is, the side wall surface 20b of the recess 30a is inclined relative to the bottom surface 20a of the recess 30a. The included angle between the side wall surface 20b and the bottom surface 20a can be an obtuse angle. For example, it can be any angle between 90° and 180°. In addition, the side wall surface 20b of the recess 30a can also be perpendicular to the bottom surface 20a. In the above examples, the recess 30a can be formed by etching the substrate 30 through an etching process, and the specific manufacturing method will be described later.

[0058] In the above examples, the side wall surface 40a of the sound hole 40 is perpendicular to the lower surface 30b of the substrate 30, but the embodiments of the present application are not limited thereto. The sound hole 40 can be of any shape. For example, the side wall surface 40a of the sound hole 40 can be an inclined surface, that is, the side wall surface 40a of the sound hole 40 is inclined relative to the lower surface 30b of the substrate 30.

[0059] When the side wall surface 20b of the recess 30a and the side wall surface 40a of the sound hole 40 are both inclined surfaces, the slopes of the side wall surface 20b of the recess 30a and the side wall surface 40a of the sound hole 40 can be the same or different.

[0060] When the slopes of the side wall surface 20b of the recess 30a and the side wall surface 40a of the sound hole 40 are the same, the side wall surface 20b of the recess 30a can be in the same plane as the side wall surface 40a of the sound hole 40, that is, the side wall surface 20b of the recess 30a can be continuous with the side wall surface 40a of the sound hole 40. At this time, the recess 30a can have no bottom surface 20a. In addition, the side wall surface 20b of the recess 30a and the side wall surface 40a of the sound hole 40 can also be connected through the bottom surface 20a of the recess 30a.

[0061] When the slopes of the side wall surface 20b of the recess 30a and the side wall surface 40a of the sound hole 40 are different, the angle between the side wall surface 40a of the sound hole 40 and the lower surface 30b of the base 30 can be an acute angle, that is, the inclination trend of the side wall surface 40a of the sound hole 40 is the same as the inclination trend of the side wall surface 20b of the recess 30a. That is to say, for the dimensions of the sound cavity 20 and the sound hole 40 in the horizontal direction, the larger the dimension is, the closer it is to the upper side. In addition, the angle between the side wall surface 40a of the sound hole 40 and the lower surface 30b of the base 30 can also be an obtuse angle, that is, the inclination trend of the side wall surface 40a of the sound hole 40 is opposite to the inclination trend of the side wall surface 20b of the recess 30a. That is to say, for the dimension of the sound cavity 20 in the horizontal direction, the larger the dimension is, the closer it is to the upper side, and for the dimension of the sound hole 40 in the horizontal direction, the smaller the dimension is, the closer it is to the upper side.

[0062] The above has been described by taking the formation of the recess 30a on the base 30 to form the sound cavity 20 as an example, but the embodiments of the present application are not limited thereto. The sound cavity 20 can also be formed by bulging the diaphragm 10 upward to form a sound cavity 20 with the upper surface of the base 30, which will be described below.

[0063] Figure 6 and Figure 7 are respectively a sectional view of another embodiment of the MEMS speaker according to the embodiment of the present application.

[0064] As Figure 6 and Figure 7 shown, the central portion of the diaphragm 10 protrudes upward, and a sound cavity 20 is formed between the central portion of the diaphragm 10 and the upper surface 30b of the base 30.

[0065] In the above example, the central portion of the diaphragm 10 can be a portion within a predetermined area around the central axis of the sound hole 40 on the diaphragm 10. That is to say, in the thickness direction z, the projection area of the central portion of the diaphragm 10 is a predetermined area centered on the center of the sound hole 40. Thus, the central axis of the sound cavity 20 overlaps with the central axis of the sound hole 40 (it can also be said that the central axes of the two overlap within the error range), further improving the performance of the speaker. However, the embodiments of the present application are not limited thereto, and the central axis of the sound cavity 20 and the central axis of the sound hole 40 may not overlap. In addition, in the case of including a plurality of sound holes 40, the central axis of the sound hole 40 described above can be the common central axis of the plurality of sound holes 40.

[0066] As Figure 6As shown, the side wall surface 20c of the sound cavity 20 can be an inclined surface, that is, the side wall surface 20c of the sound cavity 20 is inclined relative to the top surface 20d of the sound cavity 20. The angle between the side wall surface 20c and the top surface 20d can be an obtuse angle, for example, any angle between 90° and 180°. Additionally, the side wall surface 20c of the sound cavity 20 can also be perpendicular to the top surface 20d. In other words, the side wall surface 20c of the sound cavity 20 is inclined relative to the upper surface 30b of the base 30, and the angle between the side wall surface 20c and the upper surface 30b can be an acute angle, for example, any angle between 0° and 90°. Additionally, the side wall surface 20c can also be perpendicular to the upper surface 30b. Additionally, as Figure 7 shown, the side wall surface 20c of the sound cavity 20 can also be a curved surface.

[0067] In the above embodiments, the base 30 is an integral body, but the embodiments of the present application do not limit this. The base 30 can also be formed by laminating multiple substrate layers. The embodiments of the present application do not limit the number of laminated substrates. Hereinafter, an example in which the base 30 is formed by laminating two substrate layers will be described.

[0068] Figure 8 and Figure 9 are respectively a cross-sectional view of another embodiment of the MEMS speaker according to the embodiments of the present application.

[0069] As Figure 8 and Figure 9 shown, the base 30 includes a first substrate 60 laminated in the thickness direction z and a second substrate 50 located on the lower side of the first substrate 60; the first substrate 60 is formed with a first through hole 60a penetrating in the thickness direction z, and the second substrate 50 is formed with a second through hole 50a penetrating in the thickness direction z. The first through hole 60a and the second through hole 50a communicate with each other in the thickness direction z. The materials of the first substrate 60 and the second substrate 50 can be the same or different. Additionally, the second substrate 50 can also be referred to as an "enhanced substrate". The enhanced substrate is used to enhance the mechanical strength of the chip and the wafer. It can be a silicon substrate or a printed circuit board (PCB), etc. The embodiments of the present application do not limit this.

[0070] In some embodiments, the diaphragm 10 and at least a part of the first through hole 60a form the sound cavity 20; at least a part of the second through hole 50a forms the sound hole 40. For example, as Figure 8 shown, the diaphragm 10 and the first through hole 60a form the sound cavity 20, and the second through hole 50a serves as the sound hole 40. For example, as Figure 9 shown, the diaphragm 10 can also form the sound cavity 20 with a part of the first through hole 60a and the second through hole 50a, and another part of the second through hole 50a serves as the sound hole 40. For example, in Figure 9The dashed line L1 in [description] divides the sound cavity 20 and the sound hole 40; for another example, the diaphragm 10 can also form the sound cavity 20 with a part of the first through hole 60a, and the other part of the first through hole 60a and the second through hole 50a serve as the sound hole 40. For example, the sound cavity 20 and the sound hole 40 are divided by the dashed line L2 in [description]. However, those skilled in the art should understand that in the example shown in [description], the sound cavity 20 and the sound hole 40 are actually integral and continuous, and it is not possible to strictly distinguish between the sound cavity 20 and the sound hole 40. The above division by the dashed line is only for the sake of clearer explanation and should not be construed as a limitation on the embodiments of the present application. Figure 9 The dashed line L2 in [description] divides the sound cavity 20 and the sound hole 40. Figure 9 In the example shown in [description], the sound cavity 20 and the sound hole 40 are actually integral and continuous, and it is not possible to strictly distinguish between the sound cavity 20 and the sound hole 40. The above division by the dashed line is only for the sake of clearer explanation and should not be construed as a limitation on the embodiments of the present application.

[0071] In some embodiments, as Figure 8 shown, the side wall surface 60b of the first through hole 60a is perpendicular to the upper surface 60c of the first substrate 60. In this case, the side wall surface 60b is also referred to as a "vertical surface", or, as Figure 9 shown, the side wall surface 60b of the first through hole 60a is inclined with respect to the upper surface 60c of the first substrate 60. In this case, the side wall surface 60b is also referred to as an "inclined surface". Additionally, the side wall surface 60b of the first through hole 60a can also be a curved surface. For example, the side wall surface 60b of the first through hole 60a can be formed to be similar to the side wall surface 20b of the recess 30a shown in Figure 2 This application's embodiments do not limit this.

[0072] In some embodiments, as Figure 8 shown, the side wall surface 50b of the second through hole 50a is perpendicular to the upper surface 50c of the second substrate 50. In this case, the side wall surface 50b is also referred to as a "vertical surface", or, as Figure 9 shown, the side wall surface 50b of the second through hole 50a is inclined with respect to the upper surface 50c of the second substrate 50. In this case, the side wall surface 50b is also referred to as an "inclined surface". This application's embodiments do not limit this.

[0073] In some embodiments, when the side wall surfaces of the two through holes are both inclined, the slopes of the two side wall surfaces can be the same or different, and the two side wall surfaces can be continuous or discontinuous.

[0074] For example, as Figure 9 shown, the side wall surface 60b of the first through hole 60a is inclined with respect to the upper surface 60c of the first substrate 60, and the side wall surface 50b of the second through hole 50a is inclined with respect to the upper surface 50c of the second substrate 50. The slope of the side wall surface 60b of the first through hole 60a is the same as the slope of the side wall surface 50b of the second through hole 50a. Additionally, as Figure 9As shown, the side wall surface 60b of the first through hole 60a is continuous with the side wall surface 50b of the second through hole 50a. At this time, the side wall surface 60b of the first through hole 60a and the side wall surface 50b of the second through hole 50a are in the same plane. However, the embodiments of the present application are not limited to this. The side wall surface 60b of the first through hole 60a and the side wall surface 50b of the second through hole 50a may also be discontinuous. That is to say, at the interface between the first substrate 60 and the second substrate 50, the width of the first through hole 60a (for example, the sound cavity 20) is greater than or less than the width of the second through hole 50a (for example, the sound hole 40). In addition, the width of the lower end of the sound hole 40 is less than the width of the lower end of the sound cavity 20. Thus, on one hand, the width of the upper end of the sound cavity 20 can be made as large as possible, thereby expanding the effective working area of the diaphragm 10. On the other hand, the width of the substrate on both sides of the sound hole 40 (i.e., the second substrate 50) can be made greater than the width of the substrate on both sides of the sound cavity 20 (i.e., the first substrate 60), thereby ensuring the substrate strength and avoiding the occurrence of wafer fragmentation or chip breakage.

[0075] In addition, the slope of the side wall surface 60b of the first through hole 60a and the slope of the side wall surface 50b of the second through hole 50a may also be different. The side wall surface 60b of the first through hole 60a and the side wall surface 50b of the second through hole 50a may be continuous or discontinuous, as long as the width of the lower end of the sound hole 40 is less than the width of the lower end of the sound cavity 20.

[0076] In addition, it may also be that one of the side wall surface 60b of the first through hole 60a and the side wall surface 50b of the second through hole 50a is an inclined surface and the other is a vertical surface. For example, the side wall surface 60b of the first through hole 60a is an inclined surface and the side wall surface 50b of the second through hole 50a is a vertical surface, and the width of the second through hole 50a (for example, the sound hole 40) is less than the width of the lower end of the first through hole 60a (for example, the sound cavity 20).

[0077] Or, the side wall surface 60b of the first through hole 60a is a vertical surface and the side wall surface 50b of the second through hole 50a is an inclined surface. The width of the upper end of the second through hole 50a (for example, the sound hole 40) may be less than, equal to, or greater than the width of the first through hole 60a (for example, the sound cavity 20), and the width of the lower end of the sound hole 40 is less than the width of the sound cavity 20.

[0078] In addition, it may also be, as Figure 8 shown, that both the side wall surface 60b of the first through hole 60a and the side wall surface 50b of the second through hole 50a are vertical surfaces. In this case, the side wall surface 60b of the first through hole 60a and the side wall surface 50b of the second through hole 50a are discontinuous.

[0079] In the embodiments of the present application, the diaphragm 10 may have a slit 70. For example, as Figures 1 to 5As shown, the diaphragm 10 may also have no slit. For example, as Figures 6 to 9 shown. Additionally, Figures 1 to 5 the diaphragm 10 shown in Figures 6 to 9 and the diaphragm 10 shown in

[0080] may be interchangeable. The embodiments of the present application do not limit this. Figure 1 Additionally, as shown in

[0081] the slit 70 may be in the shape of a "work" character, or may be set to other shapes according to requirements. The embodiments of the present application do not limit this.

[0082] As can be seen from the above embodiments, by forming a sound cavity and sound holes on the upper and lower sides of the substrate respectively, making the width of the substrate on the left and right sides of the sound cavity narrower than the width of the substrate on the left and right sides of the sound hole, while ensuring the effective working area of the diaphragm, the strength of the substrate is enhanced, avoiding the occurrence of wafer fragmentation or chip breakage, thereby improving the performance of the MEMS speaker and reducing the production cost.

[0083] The embodiments of the present application also provide a manufacturing method for a MEMS speaker. Figure 10 is a schematic diagram of the manufacturing method of the MEMS speaker according to the embodiments of the present application.

[0084] As Figure 10 shown, the manufacturing method includes:

[0085] 1001: Form a diaphragm on the upper side in the thickness direction of the substrate,

[0086] 1002: Form a sound hole on the lower side in the thickness direction of the substrate,

[0087] 1003: Form a sound cavity between the diaphragm and the upper part in the thickness direction of the substrate, wherein the sound cavity communicates with the sound hole, and at least a part of the sound cavity in the horizontal direction in the thickness direction is larger than at least a part of the sound hole in the horizontal direction in the thickness direction.

[0088] It should be noted that the above attachments Figure 10Only the embodiments of the present application are schematically described, but the present application is not limited thereto. For example, the execution order between various operations can be appropriately adjusted. For example, operation 1002 and operation 1003 can be swapped. In addition, some other operations can be added or some of the operations can be reduced. Those skilled in the art can make appropriate modifications according to the above content, not limited to the description in the following attached Figure 10 records.

[0089] Figures 11 to 13 are respectively Figure 2 schematic diagrams of the manufacturing process of the MEMS speaker shown in Figures 14 to 16 are respectively Figure 6 schematic diagrams of the manufacturing process of the MEMS speaker shown in Figures 17 to 20 are respectively Figure 8 schematic diagrams of the manufacturing process of the MEMS speaker shown in. Hereinafter, the manufacturing method of the embodiments of the present application will be described by taking these drawings as examples.

[0090] In some embodiments, the manufacturing method may include etching on one side of the substrate 30 to form a recess 30a, and then depositing and planarizing a sacrificial material 21 on this side, as Figure 11 shown; forming a diaphragm 10 on this side, as Figure 12 shown. Additionally, slits 70 can be etched on the diaphragm 10, or the slits 70 can not be etched. Whether to etch the slits 70 can be selected according to needs, and the embodiments of the present application do not limit this. A sound hole 40 is formed on the substrate 30 by using a back etching process, and the sacrificial material 21 is exposed, as Figure 13 shown; the sacrificial material 21 is released to form a sound cavity 20, thereby forming a MEMS speaker 1, as Figure 2 shown.

[0091] In some embodiments, as Figure 11 shown, the side wall surface 20b of the recess 30a can be a curved surface, but the embodiments of the present application are not limited thereto. The side wall surface 20b of the recess 30a can also be a plane. For example, the side wall surface 20b of the recess 30a can be perpendicular to the bottom surface 20a, or the side wall surface 20b of the recess 30a can also be inclined with respect to the bottom surface 20a. The above description takes the formation of Figure 2 the MEMS speaker 1 shown as an example, but the embodiments of the present application are not limited thereto. The above manufacturing method can also be used for forming Figures 3 to 5 the MEMS speaker 1 shown.

[0092] In some embodiments, the manufacturing method may further include: before forming the diaphragm, depositing a sacrificial layer on the upper surface of the substrate, and forming the diaphragm on the upper surface of the sacrificial layer; in the step of forming the sound holes, forming the sound holes that penetrate the substrate in the thickness direction, and in the step of forming the sound cavity, releasing the sacrificial layer from the back surface of the substrate to form the sound cavity. For example, depositing a sacrificial material 21 on one side of the substrate 30, and etching the edge of the sacrificial material 21 to expose the underlying substrate 30, as Figure 14 shown; forming a diaphragm 10 on this side, as Figure 15 shown; forming sound holes 40 on the substrate 30 using a backside etching process and exposing the sacrificial material 21, as Figure 16 shown; releasing the sacrificial material 21 to form a sound cavity 20, thereby forming a MEMS speaker 1, as Figure 6 shown.

[0093] In some embodiments, Figure 14 the edge of the sacrificial material 21 shown is etched to be a bevel, so that the side wall surface 20c of the formed sound cavity 20 (as Figure 6 shown) is also a bevel, but the embodiments of the present application are not limited thereto, and the edge of the sacrificial material 21 can also be etched to be a curved surface, so as to form Figure 7 the sound cavity 20 shown.

[0094] In some embodiments, the substrate includes a first substrate and a second substrate stacked in the thickness direction and located below the first substrate. In the step of forming the diaphragm, the diaphragm is formed on the upper surface of the first substrate. In the steps of forming the sound holes and the sound cavity, a first through hole that penetrates the first substrate in the thickness direction is formed, and a second through hole that penetrates the second substrate in the thickness direction is formed. The first through hole and the second through hole communicate in the thickness direction, and at least a part of the diaphragm and the first through hole form the sound cavity; at least a part of the second through hole forms the sound hole.

[0095] In addition, in some embodiments, the manufacturing method further includes: after forming the diaphragm, bonding a temporary substrate on the upper surface of the diaphragm; after forming the sound holes and the sound cavity, removing the temporary substrate.

[0096] For example, forming a diaphragm 10 on one side of the first substrate 60, as Figure 17 shown; bonding a layer of temporary bonding substrate 80 on the upper surface of the diaphragm 10, as Figure 18 shown; thinning the first substrate 60 from the other side of the first substrate 60, for example, thinning it to 100 microns, and etching the first substrate 60 to etch away the middle part of the first substrate 60, as Figure 19As shown, additionally, optionally, when an SOI substrate is selected, this step is to remove the substrate layer and the buried oxide layer (intermediate layer) of the SOI wafer, leaving the device layer; bonding or adhering a second substrate (such as a reinforcing substrate) 50 to the lower surface of the first substrate 60, as Figure 20 shown, optionally, the second substrate 50 can be pre-etched to form a second through hole 50a, and then bonded or adhered to the lower surface of the first substrate 60, or, the second substrate 50 can be bonded or adhered to the lower surface of the first substrate 60, and then the second substrate 50 is etched to form the second through hole 50a; removing the temporary bonding substrate 80, thereby forming the MEMS speaker 1, as Figure 8 shown.

[0097] In some embodiments, when thinning the first substrate 60 and etching the middle part, the side wall of the trench can be etched into a vertical plane, for example, forming Figure 8 the first substrate 60 as shown, or the side wall of the trench can be etched into an inclined plane, for example, forming Figure 9 the first substrate 60 as shown. Additionally, the first substrate 60 can also not be thinned, but directly etched, and the side wall of the trench is etched into an inclined plane, thereby forming a through hole that is larger at the top and smaller at the bottom. The upper part of this through hole realizes the function of the sound cavity, and the lower part realizes the function of the sound hole. In this case, the second substrate 50 can also not be provided on the lower surface of the first substrate 60.

[0098] In some embodiments, as Figure 20 shown, the side wall surface 50b of the second through hole 50a of the second substrate 50 can be perpendicular to the upper surface 50c of the second substrate 50, or can be inclined relative to the upper surface 50c. For example, forming Figure 9 the second through hole 50a as shown. Additionally, the slope of the side wall surface 50b of the second through hole 50a of the second substrate 50 can be the same as or different from the slope of the side wall surface 60b of the first through hole 60a of the first substrate 60. The side wall surface 50b of the second through hole 50a of the second substrate 50 can be continuous or discontinuous with the side wall surface 60b of the first through hole 60a of the first substrate 60. The specific implementation manner can refer to the above description of the structure of the MEMS speaker, and will not be elaborated here.

[0099] Additionally, in the embodiments of the present application, the process of forming the diaphragm 10 on the substrate 30 or the first substrate 60 can be a deposition process, or the corresponding process can be selected according to the structure of the diaphragm 10. Specifically, it can refer to the related technology, and the embodiments of the present application do not limit this.

[0100] Additionally, in the embodiments of the present application, the materials of the substrate 30, the sacrificial material 21, the diaphragm 10, the first substrate 60, the second substrate 50, and the temporary bonding substrate 80 can refer to the related technology, and the embodiments of the present application do not limit this.

[0101] In addition, in the embodiments of the present application, the etching process, the back etching process, the deposition process, the release process, the bonding process, the adhesion process, and the thinning process may refer to related technologies, and the embodiments of the present application do not limit them.

[0102] The embodiments of the present application further provide an electronic device, which includes the MEMS speaker described in the foregoing embodiments. Since the structure and characteristics of the MEMS speaker have been described in detail in the above embodiments, the content is incorporated herein and the description thereof is omitted here.

[0103] The electronic device of the embodiments of the present application is, for example, a headphone or a speaker of a smart phone, etc., and the embodiments of the present application do not limit it.

[0104] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present application. It should be understood that the above are only specific embodiments of the present application and are not used to limit the protection scope of the present application. Any modifications, equivalent replacements, improvements, 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 MEMS speaker, the MEMS speaker comprising a substrate and a diaphragm located on the upper side in the thickness direction of the substrate, characterized in that, a sound cavity is formed between the diaphragm and the upper part in the thickness direction of the substrate, sound holes are formed on the lower side in the thickness direction of the substrate, the sound cavity is communicated with the sound holes, and at least a part of the sound cavity in the horizontal direction is larger than at least a part of the sound holes in the horizontal direction in the thickness direction.

2. The MEMS speaker according to claim 1, characterized in that, a depression is formed in the upper part in the thickness direction of the substrate, and the diaphragm and the depression form the sound cavity.

3. The MEMS speaker according to claim 2, characterized in that, the side wall surface of the depression is a curved surface, or, the side wall surface of the depression is a plane perpendicular to the upper surface of the substrate.

4. The MEMS speaker according to claim 2, characterized in that, the side wall surface of the depression is an inclined surface.

5. The MEMS speaker according to claim 4, characterized in that, the side wall surface of the sound hole is an inclined surface, and the slope of the side wall surface of the sound hole is the same as the slope of the side wall surface of the depression.

6. The MEMS speaker according to claim 5, characterized in that, the side wall surface of the sound hole is continuous with the side wall surface of the depression.

7. The MEMS speaker according to claim 1, characterized in that, the central part of the diaphragm protrudes upward, and the sound cavity is formed between the central part of the diaphragm and the upper surface of the substrate.

8. The MEMS speaker according to claim 7, characterized in that, the side wall surface of the sound cavity is an inclined surface.

9. The MEMS speaker according to claim 7, characterized in that, the side wall surface of the sound cavity is a curved surface.

10. The MEMS speaker according to claim 1, characterized in that, the substrate includes a first substrate stacked in the thickness direction and a second substrate located on the lower side of the first substrate; a first through hole is formed through the first substrate in the thickness direction, and a second through hole is formed through the second substrate in the thickness direction, and the first through hole and the second through hole are communicated in the thickness direction; the diaphragm and at least a part of the first through hole form the sound cavity; at least a part of the second through hole forms the sound holes.

11. The MEMS speaker according to claim 10, characterized in that, the side wall surface of the first through hole is continuous with the side wall surface of the second through hole.

12. The MEMS speaker according to claim 10, characterized in that, the side wall surface of the first through hole is perpendicular to the upper surface of the first substrate, or the side wall surface of the first through hole is inclined with respect to the upper surface of the first substrate; the side wall surface of the second through hole is perpendicular to the upper surface of the second substrate, or the side wall surface of the second through hole is inclined with respect to the upper surface of the second substrate.

13. The MEMS speaker according to claim 11, characterized in that, The side wall surface of the first through hole is inclined with respect to the upper surface of the first substrate, and the side wall surface of the second through hole is inclined with respect to the upper surface of the second substrate. The slope of the side wall surface of the first through hole is the same as the slope of the side wall surface of the second through hole.

14. A manufacturing method of a MEMS speaker, characterized in that, the manufacturing method includes: forming a diaphragm on the upper side in the thickness direction of the substrate, forming a sound hole on the lower side in the thickness direction of the substrate, forming a sound cavity between the diaphragm and the upper part in the thickness direction of the substrate, wherein the sound cavity communicates with the sound hole, and at least a part of the sound cavity in the horizontal direction has a larger size in the horizontal direction than at least a part of the sound hole in the thickness direction.

15. The manufacturing method according to claim 14, characterized in that, the manufacturing method further includes: depositing a sacrificial layer on the upper surface of the substrate before forming the diaphragm, and forming the diaphragm on the upper surface of the sacrificial layer; in the step of forming the sound hole, forming the sound hole that penetrates the substrate in the thickness direction, in the step of forming the sound cavity, releasing the sacrificial layer from the back surface of the substrate to form the sound cavity.

16. The manufacturing method according to claim 14, characterized in that, the substrate includes a first substrate laminated in the thickness direction and a second substrate located on the lower side of the first substrate, in the step of forming the diaphragm, forming the diaphragm on the upper surface of the first substrate, in the step of forming the sound hole and the sound cavity, forming a first through hole that penetrates the first substrate in the thickness direction, forming a second through hole that penetrates the second substrate in the thickness direction, the first through hole and the second through hole penetrate in the thickness direction, and at least a part of the diaphragm and the first through hole form the sound cavity; at least a part of the second through hole forms the sound hole.

17. The manufacturing method according to claim 16, characterized in that, the manufacturing method further includes: bonding a temporary substrate on the upper surface of the diaphragm after forming the diaphragm; removing the temporary substrate after forming the sound hole and the sound cavity.

18. The manufacturing method according to claim 16, characterized in that, the side wall surface of the first through hole is continuous with the side wall surface of the second through hole.

19. The manufacturing method according to claim 16, characterized in that, the side wall surface of the first through hole is perpendicular to the upper surface of the first substrate, or the side wall surface of the first through hole is inclined with respect to the upper surface of the first substrate; the side wall surface of the second through hole is perpendicular to the upper surface of the second substrate, or the side wall surface of the second through hole is inclined with respect to the upper surface of the second substrate.

20. The manufacturing method according to claim 18, characterized in that, the side wall surface of the first through hole is inclined with respect to the upper surface of the first substrate, the side wall surface of the second through hole is inclined with respect to the upper surface of the second substrate, the slope of the side wall surface of the first through hole is the same as the slope of the side wall surface of the second through hole.

21. An electronic device, characterized in that, the electronic device includes the MEMS speaker according to any one of claims 1 to 13.

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