Micro-electro-mechanical system and electroacoustic conversion device

Abstract

A micro-electro-mechanical system comprises counter electrodes, a first diaphragm, and a second diaphragm. The first diaphragm is provided with a plurality of first corrugations, each first corrugation comprises a first wave crest and a first wave trough, and the plurality of first wave crests and the plurality of first wave troughs are alternately arranged in a third direction. The second diaphragm is provided with a plurality of second corrugations, each second corrugation comprises a second wave crest and a second wave trough, and the plurality of second wave crests and the plurality of second wave troughs are alternately arranged in the third direction. The plurality of first wave crests and the plurality of second wave troughs are respectively aligned to form cavities, and the plurality of counter electrodes are respectively provided in the cavities. The plurality of first wave troughs are respectively aligned with the plurality of second wave crests, and at least some of the plurality of first wave troughs and the corresponding second wave crests are configured to be in contact with each other. The micro-electro-mechanical system maintains high acoustic compliance and sensitivity of the sealed dual-diaphragm structure, and has better firmness.

Description

A micro-electromechanical system and electroacoustic conversion device Technical Field

[0001] The present invention relates to the field of electroacoustic conversion devices, and in particular to a micro-electromechanical system and an electroacoustic conversion device. Background Art

[0002] A micro-electro-mechanical system (MEMS) typically consists of two corrugated diaphragms, a counter electrode, and a support. The two corrugated diaphragms are placed on either side of the counter electrode. The trough of one corrugated diaphragm is connected to the crest of the other by a support. A sealed space is formed between the crest of one corrugated diaphragm and the trough of the other corrugated diaphragm. The counter electrode is placed within this sealed space. The pressure within this sealed space is different from the pressure of the surrounding atmosphere outside the cavity. Technical issues

[0003] However, if this structure is subjected to high displacements, such as from strong airflow or mechanical shock, high stresses may occur in specific locations of the diaphragm, specifically, in the diaphragm corners around the first or two struts. This is because the two diaphragms are connected to each other by rigid struts, which limits the amount of deformation that can be achieved by each diaphragm individually.

[0004] It would therefore be desirable to provide an improved micro-electromechanical system that overcomes at least one of the above-mentioned problems. Technical Solutions

[0005] To solve the above technical problems, an embodiment of the present invention provides a MEMS, including:

[0006] a plurality of counter electrodes arranged along a first direction;

[0007] The first diaphragm and the second diaphragm are respectively located on opposite sides of the plurality of counter electrodes along the second direction and are airtightly connected;

[0008] A first diaphragm is provided with a plurality of first corrugations, each of the plurality of first corrugations includes a first crest and a first trough, and the plurality of first crests and the plurality of first troughs are alternately arranged along a third direction;

[0009] A second diaphragm is provided with a plurality of second corrugations, each of the plurality of second corrugations includes a second crest and a second trough, and the plurality of second crests and the plurality of second troughs are alternately arranged along a third direction;

[0010] The plurality of first wave crests and the plurality of second wave troughs are aligned to form a cavity, and the plurality of counter electrodes are respectively disposed in the cavity;

[0011] The plurality of first corrugation valleys are respectively aligned with the plurality of second corrugation peaks, and at least a portion of the plurality of first corrugation valleys and the corresponding second corrugation peaks are configured to contact each other.

[0012] In some embodiments, the cavity is hermetically sealed, and the pressure inside the cavity is less than the external atmospheric pressure.

[0013] In some embodiments, the cavity is in a vacuum state.

[0014] In some embodiments, the first wave valleys located at the outermost circle and the second outermost circle of the first diaphragm are in direct contact with the corresponding second wave peaks located at the outermost circle and the second outermost circle of the second diaphragm.

[0015] In some embodiments, the bottom of the first corrugation valley and the top of the second corrugation peak are configured to be flat.

[0016] In some embodiments, a length of a region where a first corrugation trough and a corresponding second corrugation peak contact each other in the third direction is equal to or smaller than a planar length of the first corrugation trough and the corresponding second corrugation peak.

[0017] In some embodiments, the first diaphragm further comprises one or more bumps, the bumps being disposed at the bottom of the first trough and contacting the top of the second crest. In some embodiments, the length of the bumps in the third direction is equal to or less than the length of the flat surface. In some embodiments, the bumps are circular / contacting or linear.

[0018] In some embodiments, the second diaphragm further comprises one or more bumps, the bumps being disposed at the top of the second crest and contacting the bottom of the first trough. In some embodiments, the length of the bumps in the third direction is equal to or less than the length of the plane. In some embodiments, the bumps are anti-stick bumps or are linear.

[0019] In some embodiments, the first diaphragm further includes one or more pits, wherein the pits are disposed at the bottom of the first wave valley and contact the top of the second wave peak.

[0020] In some embodiments, the second diaphragm further includes one or more pits, wherein the pits are disposed at the top of the second wave crest, and a portion of the second wave crest top other than the pits is configured to contact the bottom of the first wave valley.

[0021] In some embodiments, the bottom of the first wave valley and the top of the second wave peak are configured to be offset by a first distance along the third direction. In some embodiments, the first distance is less than the length of the plane.

[0022] In some embodiments, the third direction is radial or transverse.

[0023] In some embodiments, the top of the first corrugation peak or the bottom of the second corrugation valley is configured in a dome shape.

[0024] In some embodiments, at least one bottom portion of the first corrugation peak or at least one top portion of the second corrugation valley is configured in a dome shape.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] By removing at least some of the support between the first and second diaphragms, at least some of the first wave valleys and corresponding second wave peaks come into contact with each other. This means that, when atmospheric pressure is equal on both sides of the structure, the high-pressure gradient forces the two waves toward the counter electrode and / or toward the midplane of the system. Consequently, the two waves of the present invention effectively contact or adhere at their respective bottoms during static and normal operation. When the system is subjected to significant displacement, the waves with the support removed are free to move vertically and slide horizontally, reducing the device's maximum stress by up to 50%.

[0027] Therefore, the MEMS of the present invention has better robustness while maintaining the high acoustic compliance and sensitivity of the sealed double diaphragm.

[0028] To solve the above technical problems, an embodiment of the present invention further provides an electroacoustic conversion device, comprising the MEMS as described above, and a driving circuit electrically connected to the MEMS.

[0029] The advantages of the electroacoustic converter over the prior art are the same as those of the MEMS, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly describes the drawings used to describe the embodiments of the present invention. Obviously, the drawings described below only relate to some embodiments of the present invention. Those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0031] FIG1 is a schematic structural diagram of a MEMS according to an embodiment of the present invention.

[0032] FIG2 is a partial cross-sectional view of the MEMS in FIG1 .

[0033] FIG. 3 is a partial cross-sectional view of another MEMS according to an embodiment of the present invention.

[0034] FIG. 4 is a partial cross-sectional view of another MEMS according to an embodiment of the present invention.

[0035] FIG. 5 is a partial cross-sectional view of yet another MEMS according to an embodiment of the present invention.

[0036] FIG. 6 is a partial cross-sectional view of another MEMS according to an embodiment of the present invention.

[0037] FIG. 7 is a schematic diagram of an electroacoustic converter according to an embodiment of the present invention.

[0038] The following are the explanations of the reference numerals: The reference numerals should not be construed as limiting the claims.

[0039] 1. Counter electrode; 2. First diaphragm; 21. First corrugation; 211. First crest; 212. First trough; 22. Spoke rod; 3. Second diaphragm; 31. Second corrugation; 311. Second crest; 312. Second trough; 4. Cavity; 5. Plane; 6. Bump; 7. Concave pit; 8. Support member. Modes for Carrying Out the Invention

[0040] The present invention will be described with reference to the accompanying drawings. It should be noted that elements of similar structure or function are denoted by the same reference numerals throughout the figures. The embodiments described herein are not intended to be exhaustive or descriptive of various other embodiments, nor are they intended to limit the scope of the claims or other embodiments that would be apparent to one of ordinary skill in the art based on the embodiments described herein. Furthermore, the illustrated embodiments do not necessarily have all the aspects or advantages shown.

[0041] In the description of the present invention, it should be understood that the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may or may not be the same in type and configuration), and are not intended to indicate or imply the relative importance or quantity of the devices, elements, or components indicated. Unless otherwise specified, "plurality" means two or more.

[0042] The terms used in the description of the various described embodiments herein are intended only to describe specific embodiments and are not intended to be limiting. As used in the described embodiments and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and / or" as used herein refers to and includes any and all possible combinations of one or more of the associated listed items. It should be further understood that the terms "includes," "including," "comprises," and / or "comprising" as used in this specification specify the presence of the stated features, wholes, steps, actions, elements, and / or components, but do not preclude the presence or addition of one or more other features, wholes, steps, actions, elements, components, and / or combinations thereof.

[0043] Referring to Figures 1 and 2 , a microelectromechanical system (MEMS) according to some exemplary embodiments of the present invention is shown. The MEMS includes a plurality of counter electrodes 1 arranged along a first direction, and a first diaphragm 2 and a second diaphragm 3 disposed on opposite sides of the counter electrodes 1 along a second direction and airtightly connected. The plurality of counter electrodes 1 are spaced apart along a third direction, and a support member 8 may be disposed between adjacent counter electrodes 1. One end of the support member 8 along the second direction is connected to the first diaphragm 2, and the other end of the support member 8 along the second direction is connected to the second diaphragm 3. The first direction is expressed as a circumferential direction, the second direction is expressed as a vertical direction or thickness direction, and the third direction is expressed as a radial direction or lateral direction.

[0044] As shown in Figures 1 to 6, in some embodiments, both the first diaphragm 2 and the second diaphragm 3 are corrugated conductive diaphragms. The first corrugated conductive diaphragm is provided with a plurality of first corrugations 21, and the second corrugated conductive diaphragm is provided with a plurality of second corrugations 31. The plurality of first corrugations 21 and the plurality of second corrugations 31 are arranged in the same direction. Each of the plurality of first corrugations 21 includes a first crest 211 and a first trough 212, i.e., the plurality of first crests 211 and the plurality of first troughs 212 are arranged alternately along a third direction. Similarly, each of the plurality of second corrugations 31 includes a second crest 311 and a second trough 312, i.e., the plurality of second crests 311 and the plurality of second troughs 312 are arranged alternately along the third direction. In the drawings of the present invention, the outermost ends of the first corrugations 21 are the first crests 211, and the outermost ends of the second corrugations 31 are the second troughs 312. Of course, in other embodiments, the outermost end of the first corrugation 21 may also be the first trough 212, and the outermost end of the second corrugation 31 may correspondingly be the second crest 311. It should be noted that the right edge in Figures 2 to 6 is the edge of the MEMS.

[0045] The first wave crest 211 and the second wave trough 312 are aligned along the second direction, forming a cavity 4 to accommodate the corresponding counter electrode 1. The cavity 4 is airtightly sealed, and the pressure inside the cavity is lower than the external atmospheric pressure. For example, the cavity 4 is in a vacuum state.

[0046] At least part or all of the first wave valleys 212 are aligned with corresponding numbers of second wave peaks 311 and are in direct contact with each other (without support members), and the remaining first wave valleys 212 and second wave peaks 311 are connected to each other via support members 8 .

[0047] The first corrugated conductive diaphragm 2 and the second corrugated conductive diaphragm 3 can be made of a conductive material or include an insulating film on which a conductive element is provided. For example, the first corrugated conductive diaphragm 2 and the second corrugated conductive diaphragm 3 include a silicon nitride film, wherein a polysilicon electrode is formed on the surface of the diaphragm facing the counter electrode 1 or on the surface of the diaphragm facing away from the counter electrode 1 to provide conductivity.

[0048] In some embodiments, the support member 8 can be integrally constructed with the first corrugated conductive diaphragm 2 or the second corrugated conductive diaphragm 3. Alternatively, the support member 8 can be integrally formed with the counter electrode 1, and then a slot is formed to separate the support member 8 from the counter electrode 1. In some embodiments, the support member 8 can also be formed separately from the first corrugated conductive diaphragm 2 and the second corrugated conductive diaphragm 3. Alternatively, the support member 8 can be formed independently of the counter electrode 1, and then a slot is formed to separate the separator 8 from the counter electrode 1. In one example, after the first corrugated conductive diaphragm 2 and the second corrugated conductive diaphragm 3 are assembled together, the support member 8 is formed between the first trough 212 and the second crest 311.

[0049] Preferably, the counter electrode 1 and the support member 8 are arc-shaped and arranged on concentric arcs with a span of less than 360 degrees. The first crest 211, the first trough 212, the second crest 311, and the second trough 312 are all arc-shaped and arranged on concentric arcs with a span of less than 360 degrees. In one example, the first corrugated conductive diaphragm 2 and the second corrugated conductive diaphragm 3 are both circular. The spokes 22 are very narrow, and each slot, first crest 211, first trough 212, second crest 311, and second trough 312 spans approximately 60 degrees. That is, the first corrugated conductive diaphragm 2 is divided into six equal sections in its circumferential direction. Each section includes a set of first crests 211 and first troughs 212 arranged alternately in the radial direction of the first corrugated conductive diaphragm 2. Adjacent sections are connected to each other by spokes 22 extending radially along the first corrugated conductive diaphragm 2.

[0050] Preferably, the first wave valleys 212 are evenly arranged along the radial direction of the first corrugated conductive diaphragm 2 .

[0051] Accordingly, the second corrugated conductive diaphragm 3 is equally divided into six sections in the circumferential direction thereof, each section including a set of second crests 311 and second troughs 312 alternately arranged along the radial direction of the second corrugated conductive diaphragm 3. Adjacent sections are connected to each other by spokes 22 extending along the radial direction of the second corrugated conductive diaphragm 3.

[0052] Preferably, the second valleys 312 are evenly arranged in the radial direction of the second corrugated conductive diaphragm 3 .

[0053] The counter electrode 1 and support member 8 are divided into six equal sections along the circumference. Each section comprises a set of concentric circular arc-shaped counter electrodes 1 and support members 8 arranged radially. Adjacent sections are interconnected by spokes 22 extending radially along the first corrugated conductive diaphragm 2. The opposite ends of the arc-shaped counter electrode 1 are connected to corresponding spokes, so that the counter electrode 1 is suspended between adjacent spokes. The support member 8 is disconnected from the counter electrode 1 and spokes by slots.

[0054] Alternatively, the counter electrode 1, the support member 8, the first corrugated conductive diaphragm 2, and the second corrugated conductive diaphragm 3 can be divided into other numbers of parts, such as four or eight parts. These parts can be arranged evenly or unevenly in the radial direction of the MEMS. In other embodiments, the support member 8, the first corrugated conductive diaphragm 2, and the second corrugated conductive diaphragm 3 can have other shapes, such as square, hexagonal, octagonal, etc.

[0055] As shown in Figures 2 to 6, when only the outermost and second-outermost support members 8 of the first and second corrugated conductive diaphragms 2 and 3 are removed, the first troughs 212 of the first corrugated conductive diaphragm 2 and the second crests 311 of the second corrugated conductive diaphragm 3 come into contact with each other. Specifically, two first troughs 212 located near the edge of the first diaphragm 2 along the second direction are arranged to contact each other with the corresponding second crests 311. Because stress is greatest at the diaphragm corners around the outermost and second-outermost support members during high displacement, this design allows for greater bending freedom for the corresponding troughs 212 and crests 311, thus relieving stress.

[0056] It should be noted that the first diaphragm 2 can be provided with a first wave peak with a rounded corner 213, which is closest to the first wave valley for removing the support member, and / or the second diaphragm 3 can be provided with a second wave valley with a rounded corner 313, which is closest to the second wave peak for removing the support member, thereby further releasing stress.

[0057] As shown in Figure 2 , when the bottom of the first wave valley 212 and / or the top of the second wave peak 311 are flat surfaces 5, the first wave valley 212 and the second wave peak 311 may adhere to each other and become unable to separate under high structural displacement. To prevent this phenomenon, the following solutions can be provided to reduce the contact area between the first wave valley and the corresponding second wave peak.

[0058] As shown in Figures 3 to 5 , by providing anti-sticking structures / shapes, such as bumps or dimples, to reduce the contact area between the bottom and top of the corrugated conductive film, the first valleys 212 and second crests 311 can be prevented from adhering to each other and becoming unable to separate during high structural displacement. Specifically, along the second direction, the length of the contact portion between the first valleys 212 and second crests 311 is less than the length of the flat surface 5 .

[0059] Specifically, as shown in Figures 3 and 4, in some embodiments, one or more bumps 6 may be provided at the bottom of the outermost and second-outermost first troughs 212 of the first diaphragm 2, and / or at the top of the outermost and second-outermost second crests 311 of the second diaphragm 3. The length of the bumps 6 along the third direction is less than the length of the flat surface 5 at the bottom of the first trough 212 and the top of the second crest 311. By contacting the bumps 6 with the flat surface 5 at the top of the second crest 311, or by contacting the bumps 6 with the flat surface 5 at the bottom of the first trough 212, or by contacting the flat surface 5 at the bottom of the first trough 212 with the flat surface 5 at the top of the second crest 311, the contact area at the bottom of the corrugated conductive film can be reduced, thereby preventing the first trough 212 and the second crest 311 from adhering to each other and becoming unable to separate during high structural displacement. Preferably, to prevent the bumps 6 from adhering to the flat surface 5 of the first trough 212 or the second crest 311 and increasing stress, in this example, the bumps 6 are anti-adhesion bumps.

[0060] Specifically, as shown in FIG5 , in other embodiments, one or more pits 7 may be provided at the bottom of the outermost and second-outermost first troughs 212 of the first diaphragm 2, and / or one or more pits 7 may be provided at the top of the outermost and second-outermost second crests 311 of the second diaphragm 3. The length of the pits 7 along the third direction is less than the length of the plane 5 at the bottom of the first troughs 212 and the top of the second crests 311. By ensuring that the portion of the bottom of the first troughs 212 other than the pits 7 contacts the plane 5 at the top of the second crests 311, or that the portion of the top of the second crests 311 other than the pits 7 contacts the plane 5 at the bottom of the first troughs 212, or that the portion of the bottom of the first troughs 212 other than the pits 7 contacts the portion of the top of the second crests 311 other than the pits 7, the contact area at the bottom of the corrugated conductive film can be reduced, thereby preventing the first troughs 212 and the second crests 311 from adhering to each other and being unable to separate during high structural displacement.

[0061] Specifically, as shown in Figure 6 , in yet another embodiment, the bottom of the first trough 212 and the top of the second crest 311 are both plane 5. To prevent the first trough 212 and the second crest 311 from adhering to each other and being unable to separate during high structural displacement, the corrugations involved in the pressure-bonding can be offset by a certain length. Specifically, the bottom of the first trough 212 and / or the top of the second crest 311 are offset along a third direction by a first distance, where the first distance is less than the length of the plane 5. By offsetting the first trough 212 and the second crest 311, the shared plane area can be reduced in various ways, thereby mitigating potential adhesion risks.

[0062] In other embodiments, the shape of the corrugations can also be modified to achieve similar functions as anti-stiction structures. Here, the bottom shape of one diaphragm (i.e., the peak / trough shape) is designed to reduce the contact surface with the top of the other diaphragm in the absence of support member 8. When the bottom corrugations are implemented, a dome shape can be easily achieved. Similarly, it can be a single dome shape or multiple domes, and this shape can also be achieved with the top diaphragm.

[0063] Because the high-pressure gradient forces the two corrugations together, they effectively merge at their respective bases (peaks or troughs). However, during the highly nonlinear bending exhibited in shock and drop tests, the two corrugations are free to move in the second direction and slide in the first and third directions. This eliminates the need to conform one diaphragm shape to another by using a portion of the device with this corrugated structure. Consequently, a significant factor of additional bending is eliminated from the diaphragm, reducing stress in this area by up to 50%.

[0064] Another embodiment of the present invention further provides an electroacoustic transducer, as shown in Figure 7, comprising the aforementioned MEMS 701 and a driving circuit 702 electrically connected to the MEMS 701. The electroacoustic transducer 700 may be a MEMS microphone or a speaker.

[0065] Although the present invention has been described with reference to one or more embodiments, the above description of the embodiments is intended only to enable those skilled in the art to practice or use the present invention. It should be understood by those skilled in the art that various modifications may be made without departing from the spirit or scope of the present invention. The embodiments described above should not be construed as limiting the present invention, the scope of which should be determined with reference to the claims that follow.

Claims

1. A microelectromechanical system, characterized in that, Comprising: A plurality of counter electrodes arranged along a first direction; A first diaphragm and a second diaphragm, respectively located on opposite sides of the plurality of counter electrodes along a second direction and hermetically connected; Wherein, the first diaphragm is provided with a plurality of first corrugations, each of the plurality of first corrugations includes a first peak and a first valley, and the plurality of first peaks and the plurality of first valleys are alternately arranged along a third direction; The second diaphragm is provided with a plurality of second corrugations, each of the plurality of second corrugations includes a second peak and a second valley, and the plurality of second peaks and the plurality of second valleys are alternately arranged along the third direction; The plurality of first peaks and the plurality of second valleys are respectively aligned to form cavities, and the plurality of counter electrodes are respectively arranged in the cavities; and The plurality of first valleys and the plurality of second peaks are respectively aligned, and at least some of the plurality of first valleys and the corresponding second peaks are arranged to be in contact with each other.

2. The microelectromechanical system according to claim 1, wherein The cavity is hermetically sealed, and the internal pressure of the cavity is less than the external atmospheric pressure.

3. The microelectromechanical system according to claim 2, wherein, The cavity is in a vacuum state.

4. The microelectromechanical system according to claim 1, characterized in that, The first valleys located in the outermost and the second outermost circles of the first diaphragm are in direct contact with the corresponding second peaks located in the outermost and the second outermost circles of the second diaphragm.

5. The microelectromechanical system according to claim 4, characterized in that, The bottom of the first valley and the top of the second peak are set to be flat.

6. The microelectromechanical system according to claim 5, characterized in that, The length of the region where the first valley and the corresponding second peak are in contact with each other in the third direction is equal to or less than the length of the planes of the first valley and the corresponding second peak.

7. The microelectromechanical system according to claim 5, wherein, The first diaphragm further includes one or more bumps, and the bumps are arranged at the bottom of the first valley and are in contact with the top of the second peak.

8. The microelectromechanical system according to claim 7, wherein The length of the bump in the third direction is equal to or less than the length of the plane.

9. The microelectromechanical system according to claim 8, wherein, The bump is circular or linear.

10. The microelectromechanical system according to claim 5, wherein The second diaphragm further includes one or more bumps, and the bumps are arranged at the top of the second peak and are in contact with the bottom of the first valley.

11. The microelectromechanical system according to claim 10, characterized in that, The length of the bump in the third direction is equal to or less than the length of the plane.

12. The microelectromechanical system according to claim 11, wherein, The bump is an anti-sticking bump or is linear.

13. The microelectromechanical system according to claim 1, characterized in that, The first diaphragm further includes one or more pits, and the pits are arranged at the bottom of the first valley, and the portion of the bottom of the first valley other than the pits is configured to be in contact with the top of the second peak.

14. The microelectromechanical system according to claim 1, wherein, The second diaphragm further includes one or more pits, and the pits are arranged at the top of the second peak, and the portion of the top of the second peak other than the pits is configured to be in contact with the bottom of the first valley.

15. The microelectromechanical system according to claim 5, wherein, The bottom of the first valley and the top of the second peak are configured to be offset by a first distance along the third direction.

16. The microelectromechanical system according to claim 15, wherein The first distance is less than the length of the plane.

17. The microelectromechanical system according to claim 15, characterized in that, The third direction is a radial direction.

18. The microelectromechanical system according to claim 1, characterized in that, The top of the first peak or the bottom of the second valley is set to be in a dome shape.

19. The microelectromechanical system according to claim 18, wherein, At least one bottom of the first peak or at least one top of the second valley is configured to be in a dome shape.

20. An electroacoustic conversion device, characterized in that, Comprising a microelectromechanical system according to any one of claims 1 to 19, and a driving circuit electrically connected to the microelectromechanical system.

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