MEMS

Abstract

A micro-electromechanical system comprises a spacer layer, a first corrugated conductive diaphragm and a second corrugated conductive diaphragm. The spacer layer comprises a counter electrode wall, a slot and a support wall extending in a first direction. The counter electrode wall, the slot and the support wall are arranged alternately in a second direction. The first corrugated conductive diaphragm comprises a first wave crest and a first wave trough arranged alternately in the second direction, and the second corrugated conductive diaphragm comprises a second wave crest and a second wave trough arranged alternately in the second direction. The spacer layer is received in a cavity formed by the first and second corrugated conductive diaphragms. The support wall is respectively sandwiched between the aligned first and second wave crests. The counter electrode walls are respectively suspended in corresponding chambers formed between the aligned first and second wave crests and the second wave troughs. The micro-electromechanical system of the present invention has a high level of acoustic compliance and sensitivity.

Description

[Technical field]

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

[0002] Existing MEMS are generally provided with a double membrane located on opposite sides of a counter electrode. A sealed space is formed between the double membranes, which can be at a pressure different from the surrounding atmosphere. If the pressure in the sealed space is significantly reduced below atmospheric pressure, such as less than 10% of atmospheric pressure, the acoustic damping of the airflow through the counter electrode will be significantly reduced. The reduction in acoustic damping will lead to an increase in the microphone signal-to-noise ratio (SNR). Existing MEMS are provided with two planar membranes, which are connected by a series of pillars.

[0003] However, because the pressure within the sealed space is less than atmospheric pressure, there is a significant pressure difference between the membranes, which causes the membrane to deform between the pillars and generates local tensile stresses that increase the stiffness of the membrane. This makes it a major challenge to design a dual-membrane structure that minimizes deformation between the pillars while allowing the dual-membrane structure to respond to incoming sound pressure.

[0004] Therefore, there is a need to provide an improved micro-electromechanical system that can overcome the above problems. [Summary of the invention]

[0005] The object of the present invention is to overcome the above technical problems and provide a micro-electromechanical system with a high level of acoustic compliance and sensitivity.

[0006] To achieve the above object, the present invention provides a micro-electromechanical system, comprising:

[0007] A spacer layer having a plurality of support walls and counter electrode walls extending in a first direction, wherein the counter electrode walls and the support walls are alternately arranged in a second direction, and a narrow groove is formed between adjacent counter electrode walls and support walls to separate the support walls and the counter electrode walls;

[0008] A first corrugated conductive diaphragm includes a plurality of first wave crests and first wave valleys alternately arranged in a second direction;

[0009] A second corrugated conductive diaphragm includes a plurality of second wave crests and second wave valleys alternately arranged in a second direction;

[0010] wherein the first corrugated conductive diaphragm and the second corrugated conductive diaphragm are respectively located on opposite sides of the spacer layer to form a cavity, the first wave crests are respectively aligned with the second wave troughs, and the first wave troughs are respectively aligned with the second wave crests;

[0011] The spacer layer is received in the cavity, and its supporting walls are respectively sandwiched between the aligned first wave valleys and the second wave peaks;

[0012] The micro-electromechanical system further includes chambers formed between the aligned first wave crests and second wave troughs and the adjacent support walls; the electrode walls are respectively suspended in the corresponding chambers.

[0013] As an optimization, the chamber is hermetically sealed and the internal pressure is less than the external atmosphere.

[0014] As an optimization, the internal pressure of the chamber is less than 0.2 atm.

[0015] As an optimization, the chamber is vacuum.

[0016] As an optimization, the first corrugated conductive membrane is made of a conductive material or comprises an insulating film on which a conductive element is arranged; and / or

[0017] The second corrugated conductive membrane is made of a conductive material or includes an insulating film on which a conductive element is disposed.

[0018] As an optimization, the counter electrode wall includes a single conductor, so that a first capacitor is formed between the first corrugated conductive diaphragm and the single conductor, and a second capacitor is formed between the second corrugated conductive diaphragm and the single conductor.

[0019] As an optimization, the electrode wall includes a first surface facing the first corrugated conductive diaphragm and a second surface facing the second corrugated conductive diaphragm, and further includes conductive elements respectively arranged on the first and second surfaces, so that a first capacitor is formed between the first corrugated conductive diaphragm and the conductive element arranged on the first surface of the spacer layer, and a second capacitor is formed between the second corrugated conductive diaphragm and the conductive element arranged on the second surface of the spacer layer.

[0020] As an optimization, the first wave crests and wave troughs are evenly distributed in the second direction.

[0021] As an optimization, the first wave crests and wave troughs are unevenly distributed in the second direction.

[0022] As an optimization, the distance between adjacent supporting walls is greater than 20 um.

[0023] As an optimization, the first corrugated conductive diaphragm further comprises a plurality of spokes extending along the second direction, and each of the first wave crests and first wave troughs alternately arranged in the second direction extends between two adjacent spokes in the first direction, thereby forming a spider shape.

[0024] As an optimization, the first wave crest and the wave trough are arranged on concentric circular arcs.

[0025] As an optimization, the first wave crests and the first wave troughs extend in an arc shape along the first direction, adjacent first wave crests are spaced apart from each other, and adjacent first wave troughs are spaced apart from each other, so that spokes extending along the second direction are formed therebetween.

[0026] As an optimization, each of the first crests and troughs spans an arc having an angle of 30 to 90 degrees.

[0027] As an optimization, the first corrugated conductive diaphragm has a circular structure, including multiple parts, each part includes a group of first crests and first troughs alternately arranged in the second direction, and adjacent parts are interconnected by spokes extending along the diameter direction of the first corrugated conductive diaphragm.

[0028] As an optimization, the first groove is formed on a surface of the first wave valley away from the spacer layer.

[0029] As an optimization, the spacer layer further comprises a plurality of spokes extending in the second direction, the counter electrode walls are respectively connected between adjacent spokes, and the supporting wall is disconnected from the counter electrode wall and the spokes by a narrow groove.

[0030] As an optimization, the spacer layer has a circular structure and includes multiple parts, each part includes a group of electrode walls and support walls alternately arranged in the second direction, and adjacent parts are connected to each other by spokes extending along the diameter direction of the spacer layer; the electrode walls are respectively connected between adjacent spokes, and the support walls are disconnected from the electrode walls and spokes by narrow grooves.

[0031] As an optimization, the counter electrode wall is perforated with slits or holes.

[0032] The present invention further provides an electroacoustic conversion device, comprising the above-mentioned micro-electromechanical system and a dedicated integrated circuit electrically connected to the micro-electromechanical system.

[0033] The MEMS of the present invention has a high level of acoustic compliance (diaphragm displacement under acoustic load) while being resistant to deformation due to the high pressure difference between the reduced pressure in the enclosed space and atmospheric pressure. This high acoustic compliance allows for high microphone sensitivity.

Brief Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in the field of the present invention, other drawings can be obtained based on these drawings without creative work, among which:

[0035] Figure 1 A micro-electromechanical system related to an exemplary embodiment of the present invention is shown.

[0036] Figure 2 yes Figure 1 Partial cross-sectional view of a micro-electromechanical system.

[0037] Figure 2a Shown is a partial cross-sectional view of a micro-electromechanical system according to another exemplary embodiment of the present invention.

[0038] Figure 3 Shown Figure 1 The spacer layer of the MEMS.

[0039] Figure 4 Application shown Figure 1 An electroacoustic conversion device of a micro-electromechanical system. [Specific implementation method]

[0040] The specific implementation part will further illustrate the present invention with reference to the accompanying drawings. It should be noted that in all the drawings, elements with similar structures or functions are represented by similar reference numerals. The embodiments described herein are not intended to be exhaustive or descriptive of various other embodiments, or to limit the scope of the claims or the scope of some other embodiments. In addition, the embodiments shown do not need to have all the aspects or advantages shown.

[0041] refer to Figure 1 and Figure 2 , a micro-electromechanical system 10 includes a spacer layer 30 , and a first corrugated conductive film 50 and a second corrugated conductive film 70 respectively disposed on opposite sides of the spacer layer 30 .

[0042] The spacer layer 30 is located in a cavity 80 formed by the first and second diaphragms 50 and 70. The spacer layer 30 includes a plurality of counter electrode walls 32, a support wall 34, and a slot 36 between adjacent counter electrode walls 32 and support walls 34. The micro-electromechanical system 10 also includes conductive elements 322 and 324 disposed on first and second surfaces of the counter electrode walls 32, respectively, and the conductive elements 322 and 324 are used as counter electrodes. The spacer layer 30 also includes a plurality of spokes 37, which are configured to mount the counter electrode wall 32 to the electroacoustic converter 100 (such as Figure 4 The slots 36 surround the corresponding counter electrode walls 32 and penetrate the spacer layer 30 in the depth direction of the spacer layer 30, thereby separating the support wall 34 from the counter electrode wall 32 and the spokes 37. The counter electrode wall 32 and the support wall 34 extend in a first direction, which is also referred to as the circumferential direction or the longitudinal direction in the present invention; the counter electrode wall 32, the slots 36 and the support wall 34 are alternately arranged in a second direction, which is also referred to as the radial direction or the transverse direction in the present invention; and the spokes 37 extend in the second direction.

[0043] The first corrugated conductive diaphragm 50 includes a plurality of first crests 52 and a plurality of first valleys 54 alternately arranged in a second direction. The first grooves 54 are sunken from adjacent first crests 52 toward the spacer layer 30. The first grooves 56 are correspondingly formed on a surface of the first valley 54 away from the spacer layer 30. The first crests 52 are aligned with the counter electrode walls 32, respectively. The first valleys 54 are aligned with the support walls 34, respectively. The first corrugated conductive diaphragm 50 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 50 includes a silicon nitride film, wherein a polysilicon electrode is formed on a surface of the diaphragm 50 facing the spacer layer 30 to provide conductivity.

[0044] The second corrugated conductive diaphragm 70 includes a plurality of second crests 72 and a plurality of second valleys 74 alternately arranged in a second direction. The second crests 72 sink from the second valleys 74 in the direction toward the spacer layer 30. Accordingly, a second groove 76 is formed on the surface of the second crest 72 away from the spacer layer 30. The second valleys 74 are aligned with the counter electrode walls 32, respectively. The second crests 72 are aligned with the support walls 34, respectively. Preferably, the second corrugated conductive diaphragm 70 is symmetrical with the first corrugated conductive diaphragm 50 about the spacer layer 30. The second corrugated conductive diaphragm 70 may be made of a conductive material or include an insulating film on which a conductive element is disposed. For example, the second corrugated conductive diaphragm 70 includes a silicon nitride film, and a polysilicon electrode is formed on the surface of the diaphragm 70 facing the spacer layer 30 to provide conduction. In fact, the support wall 34 can be integrally constructed with the first corrugated conductive diaphragm 50 or the second corrugated conductive diaphragm 70; or, the support wall 34 can be integrally formed with the counter electrode wall 32, and then a narrow groove 36 is formed to separate the support wall 34 from the counter electrode wall 32; or the support wall 34 can be formed between the first trough 54 and the second crest 72 of the first corrugated conductive diaphragm 50 and the second corrugated conductive diaphragm 70 after they are assembled together.

[0045] The first wave valley 54 and the second wave peak 72 are in contact with the opposite surface of the support wall 34, that is, the support wall 34 is sandwiched between the corresponding first wave valley 54 and the second wave peak 72. The chamber 38 is formed between the aligned first wave peak 52, the second wave valley 74 and the adjacent support wall 34, respectively. In some embodiments, the chamber 38 is sealed from the external atmosphere and vacuum; alternatively, the pressure in the chamber 38 may be in a reduced pressure atmosphere, for example, less than 0.2atm. In some embodiments, the pressure in the chamber 38 is equal to 0.1atm. The counter electrode wall 32 is suspended in the corresponding sealed chamber 38 by the spokes 37. The first wave peak 52 is spaced apart from the conductive element 322 of the counter electrode wall 32; thereby forming a first capacitor therebetween. The second wave valley 74 is spaced apart from the corresponding conductive element 324 of the counter electrode wall 32, thereby forming a second capacitor therebetween. The first wave crest 52 and the second wave valley 74 can be displaced relative to the corresponding counter electrode wall 32 in response to the pressure applied thereto to change the distance between the first wave crest 52 and the second wave valley 74 and the corresponding counter electrode wall 32 of the spacer layer 30, so that the capacitance changes and the electrical signal is output accordingly. Alternatively, the counter electrode wall 32 includes a single conductor, so that a first capacitor is formed between the first corrugated conductive diaphragm 50 and the single conductor and a second capacitor is formed between the second corrugated conductive diaphragm 50 and the single conductor. In some embodiments, the counter electrode wall 32 is perforated with slits or holes 326, such as Figure 2a As shown, slits or holes 326 are provided to facilitate passage of air / gas through the counter electrode wall 32 .

[0046] Preferably, the counter electrode wall 32 and the support wall 34 are arc-shaped and arranged on concentric arcs with a span of less than 360 degrees. The first crest 52, the first trough 54, the second crest 72, and the second trough 74 are arc-shaped and arranged on concentric arcs with a span of less than 360 degrees. In the present embodiment, the spacer layer 30, the first corrugated conductive diaphragm 50, and the second corrugated conductive diaphragm 70 are circular. The spoke 58 is very narrow and each of the slots 36, the first crest 52, the first trough 54, the second crest 72, and the second trough 74 spans approximately 60 degrees. That is, the first corrugated conductive diaphragm 50 is divided into six parts in its circumferential direction. Each part includes a group of first crests 52 and first troughs 54 alternately arranged in the radial direction of the first corrugated conductive diaphragm 50. Adjacent parts are connected to each other by spokes 58 extending in the diameter direction of the first corrugated conductive diaphragm 50.

[0047] Preferably, the first troughs 54 are evenly arranged along the radial direction of the first corrugated conductive diaphragm 50, and the distance D between adjacent supporting walls 34 is greater than 20 μm. Accordingly, the second corrugated conductive diaphragm 70 is divided into six parts, each of which includes a group of second crests 72 and second troughs 74 arranged along the radial direction of the second corrugated conductive diaphragm 70. Adjacent parts are connected to each other by spokes 58 extending along the diameter direction of the second corrugated conductive diaphragm 70.

[0048] Preferably, the second trough 74 is uniformly arranged in the radial direction of the second corrugated conductive diaphragm 70. The spacer layer 30 is divided into six parts, each of which includes a group of concentric arc-shaped counter electrode walls 32 and support walls 34 arranged in the radial direction of the spacer layer 30. Adjacent parts are connected to each other by spokes 37 extending in the diameter direction of the spacer layer 30. The opposite ends of the arc-shaped counter electrode wall 32 are respectively connected to the corresponding spokes 37, so that the counter electrode wall 32 is suspended between adjacent spokes. The support wall 34 is disconnected from the counter electrode wall 32 and the spoke 37 by the narrow groove 36. Alternatively, the spacer layer 30, the first corrugated conductive diaphragm 50 and the second corrugated conductive diaphragm 70 can be divided into other numbers of parts, such as four parts or eight parts, etc. These parts can be uniformly or unevenly arranged in the radial direction of the micro-electromechanical system 10. In some other embodiments, the spacer layer 30, the first corrugated conductive diaphragm 50 and the second corrugated conductive diaphragm 70 can have other shapes, such as square, hexagonal, octagonal, etc.

[0049] The spacer layer 30 is accommodated in a cavity 80 formed between the first and second corrugated conductive diaphragms 50, 70. The peripheries of the first and second corrugated conductive diaphragms 50, 70 may be anchored to the base of the electroacoustic converter 100. In this embodiment, the first corrugated conductive diaphragm 50 is an upper diaphragm, and the second corrugated conductive diaphragm 70 is a lower diaphragm mounted on a substrate (not shown).

[0050] In the present invention, the corrugated structure formed in the thin film 50, 70 helps to increase the acoustic compliance of the microphone of the micro-electromechanical system 10 to which the present invention is applied, due to the reduction of the residual stress in the diaphragm 50, 70. The first wave valley 54 and the second wave peak 72 of the diaphragm 50, 70 are connected together by the corresponding support wall 34 of the spacer layer 30. Therefore, no additional connecting pillars / columns are required to strengthen the diaphragm 50, 70. The first and second diaphragms 50, 70 are closer together, so the second moment of inertia is lower.

[0051] The outer surfaces of the first crest 52 and the second trough 74 away from the spacer layer 30 are configured to receive atmospheric pressure. In a cross section parallel to the displacement direction of the diaphragms 50, 70, the outer surfaces of the first crest 52 and the second trough 74 are slightly arc-shaped and anchored on both sides by adjacent troughs 54 and crests 74, which makes the MEMS 10 much less susceptible to deformation due to atmospheric pressure. This allows the diaphragms 50, 70 to use thinner materials with the same degree of deformation as current MEMS, thereby forming a more compliant structure.

[0052] The micro-electromechanical system according to the above-described embodiment of the present invention has a high level of acoustic compliance (diaphragm displacement under acoustic load) while being resistant to deformation due to the high pressure difference between the reduced pressure in the enclosed space and the atmospheric pressure. This high acoustic compliance allows for high microphone sensitivity.

[0053] Figure 4 The electroacoustic conversion device 100 using the micro-electromechanical system 10 is shown. The electroacoustic conversion device 100 further includes an application specific integrated circuit (ASIC) 90 electrically connected to the micro-electromechanical system 10. The electroacoustic conversion device 100 may be a micro-electromechanical system or a speaker.

[0054] Although the present invention has been described in conjunction with one or more embodiments, the description of the above embodiments is only intended 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 above embodiments should not be construed as limiting the present invention, and the scope of the present invention is determined by reference to the following claims.

Claims

1. A micro-electromechanical system, comprising: A spacer layer having a plurality of support walls and counter electrode walls extending in a first direction, wherein the counter electrode walls and the support walls are alternately arranged in a second direction, and a narrow groove is formed between adjacent counter electrode walls and support walls to separate the support walls and the counter electrode walls; A first corrugated conductive diaphragm includes a plurality of first wave crests and first wave valleys alternately arranged in a second direction; A second corrugated conductive diaphragm includes a plurality of second wave crests and second wave valleys alternately arranged in a second direction; wherein the first corrugated conductive diaphragm and the second corrugated conductive diaphragm are respectively located on opposite sides of the spacer layer to form a cavity, the first wave crests are respectively aligned with the second wave troughs, and the first wave troughs are respectively aligned with the second wave crests; The spacer layer is received in the cavity, and its supporting walls are respectively sandwiched between the aligned first wave valleys and the second wave peaks; The micro-electromechanical system further includes chambers formed between the aligned first wave crests and second wave troughs and the adjacent support walls; the electrode walls are respectively suspended in the corresponding chambers.

2. The micro-electromechanical system according to claim 1, characterized in that: The chamber is hermetically sealed and the internal pressure is less than the external atmosphere.

3. The micro-electromechanical system according to claim 2, characterized in that: The internal pressure of the chamber is less than 0.2 atm.

4. The micro-electromechanical system according to claim 3, characterized in that: The chamber is evacuated.

5. The micro-electromechanical system according to claim 1, characterized in that: The first corrugated conductive film is made of a conductive material or comprises an insulating film on which a conductive element is arranged; and / or The second corrugated conductive membrane is made of a conductive material or includes an insulating film on which a conductive element is disposed.

6. The micro-electromechanical system according to claim 5, characterized in that: The counter electrode wall includes a single conductor such that a first capacitance is formed between the first corrugated conductive diaphragm and the single conductor, and a second capacitance is formed between the second corrugated conductive diaphragm and the single conductor.

7. The micro-electromechanical system according to claim 5, characterized in that: The electrode wall includes a first surface facing the first corrugated conductive diaphragm and a second surface facing the second corrugated conductive diaphragm, and further includes conductive elements respectively arranged on the first and second surfaces, so that a first capacitor is formed between the first corrugated conductive diaphragm and the conductive element arranged on the first surface of the spacer layer, and a second capacitor is formed between the second corrugated conductive diaphragm and the conductive element arranged on the second surface of the spacer layer.

8. The micro-electromechanical system according to claim 1, characterized in that: The first wave crests and wave troughs are evenly distributed in the second direction.

9. The micro-electromechanical system according to claim 1, characterized in that: The first wave crests and wave troughs are unevenly distributed in the second direction.

10. The micro-electromechanical system according to claim 1, wherein: The distance between adjacent supporting walls is greater than 20um.

11. The micro-electromechanical system according to claim 1, characterized in that: The first corrugated conductive film further includes a plurality of spokes extending along the second direction, and each of the first wave crests and first wave troughs alternately arranged in the second direction extends between two adjacent spokes in the first direction, thereby forming a spider shape.

12. The micro-electromechanical system according to claim 1, characterized in that: The first wave crests and wave troughs are arranged on concentric circular arcs.

13. The micro-electromechanical system according to claim 7, characterized in that: The first wave crests and the first wave troughs extend in an arc shape along a first direction, adjacent first wave crests are spaced apart from each other, and adjacent first wave troughs are spaced apart from each other, so that spokes extending along a second direction are formed therebetween.

14. The micro-electromechanical system according to claim 13, characterized in that: Each of the first crests and troughs spans an arc having an angle of 30 to 90 degrees.

15. The micro-electromechanical system according to claim 13, characterized in that: The first corrugated conductive film has a circular structure and includes a plurality of parts, each part includes a group of first crests and first troughs alternately arranged in a second direction, and adjacent parts are connected to each other through spokes extending along the diameter direction of the first corrugated conductive film.

16. The micro-electromechanical system according to claim 1, wherein: The first groove is formed on a surface of the first wave valley away from the spacer layer.

17. The micro-electromechanical system according to claim 1, characterized in that: The spacer layer further comprises a plurality of spokes extending in the second direction, the counter electrode walls are respectively connected between adjacent spokes, and the supporting wall is disconnected from the counter electrode wall and the spokes by a narrow groove.

18. The micro-electromechanical system according to claim 17, characterized in that: The spacer layer has a circular structure and includes a plurality of parts, each part including a group of counter electrode walls and support walls alternately arranged in the second direction, and adjacent parts connected to each other by spokes extending along the diameter direction of the spacer layer; the counter electrode walls are respectively connected between adjacent spokes, and the support walls are disconnected from the counter electrode walls and the spokes by narrow grooves.

19. The micro-electromechanical system according to claim 1, wherein: The counter electrode wall is perforated with slits or holes.

20. An electroacoustic conversion device, comprising the micro-electromechanical system according to claim 1, and an application-specific integrated circuit electrically connected to the micro-electromechanical system.

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