A MEMS component

Abstract

The present invention discloses a MEMS element, comprising: a substrate, a back cavity passing through the substrate; a diaphragm connected to the substrate and covering the back cavity; the diaphragm comprising an upper diaphragm and a lower diaphragm disposed opposite each other, with a storage space formed between the upper and lower diaphragms; a counter electrode disposed within the storage space; a plurality of support members disposed between the upper and lower diaphragms, with opposite ends of the support members connected to the upper and lower diaphragms, respectively; and a plurality of first chambers defined within at least one of the support members; the first chambers having upper ventilation slots extending through the upper diaphragm and lower ventilation slots extending through the lower diaphragm, the upper ventilation slots communicating with the lower ventilation slots. Compared to the prior art, the present invention has upper and lower ventilation slots communicating with each other to form a ventilation structure, thereby not reducing the local stiffness of the diaphragm while improving the flexibility of the diaphragm and the sensitivity of the microphone.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-electromechanical systems, in particular to a MEMS element. Background Art

[0002] Prior art has developed and produced dual-membrane microphones with two membranes on opposite sides of a counter electrode. This creates a sealed containment space between the two membranes, which can maintain different pressures relative to the external environment. Reducing the pressure within this containment space significantly reduces the self-noise associated with the counter electrode (a major noise source in MEMS microphones).

[0003] In the prior art, there is a ventilation hole in the center of the two diaphragms. This ventilation hole passes through the central counter electrode, which may cause stress concentration in the overall structure under high pressure load and affect the rigidity of the overall structure. Summary of the Invention

[0004] The purpose of the present invention is to provide a MEMS element to solve the technical problems in the prior art.

[0005] The present invention provides a MEMS element, comprising:

[0006] a substrate, a back cavity passing through the substrate;

[0007] a diaphragm connected to the substrate and covering the back cavity, the diaphragm comprising an upper diaphragm and a lower diaphragm arranged opposite to each other, with a receiving space formed between the upper diaphragm and the lower diaphragm;

[0008] a counter electrode, disposed in the accommodation space;

[0009] a plurality of concentric and spaced apart support members, disposed between the upper diaphragm and the lower diaphragm and spaced apart from the counter electrode, wherein opposite ends of the support members are respectively connected to the upper diaphragm and the lower diaphragm, and a plurality of first chambers are defined in at least one of the support members;

[0010] in:

[0011] The MEMS element has an upper ventilation groove extending through the upper diaphragm corresponding to the first chamber, and a lower ventilation groove extending through the lower diaphragm corresponding to the first chamber. The upper ventilation groove, the first chamber and the lower ventilation groove are in communication.

[0012] A MEMS element as described above, wherein preferably, the upper diaphragm includes a plurality of first protrusions protruding toward the accommodating space and spaced apart from each other, the lower diaphragm includes a plurality of second protrusions protruding toward the accommodating space and spaced apart from each other, the plurality of support members, the plurality of first protrusions and the plurality of second protrusions are in one-to-one correspondence, the two ends of the support member are respectively connected to the first protrusion and the second protrusion, the upper ventilation groove is opened on the first protrusion, and the lower ventilation groove is opened on the second protrusion.

[0013] In the MEMS element as described above, preferably, the first chamber is only opened in the support member located at the periphery of the diaphragm.

[0014] In the MEMS element as described above, preferably, the inner diameter of the upper ventilation groove is larger than the inner diameter of the lower ventilation groove.

[0015] In the MEMS element as described above, preferably, the inner diameter of the upper ventilation groove is smaller than the inner diameter of the lower ventilation groove.

[0016] A MEMS element as described above, wherein preferably, the portions of the upper diaphragm and the lower diaphragm corresponding to the support member in which the first chambers are opened include a first membrane layer and a second membrane layer, the first membrane layer is closer to the accommodation space than the second membrane layer, the first protrusion is formed on the first membrane layer of the upper diaphragm, and the second protrusion is formed on the first membrane layer of the lower diaphragm, and the MEMS element also includes a first through hole and a second through hole respectively penetrating the second membrane layer of the upper diaphragm and the second membrane layer of the lower diaphragm, the first through hole, the upper ventilation groove, the first chamber, the lower ventilation groove and the second through hole are connected in sequence, and the aperture of the first through hole is not equal to the aperture of the second through hole.

[0017] In the MEMS element as described above, preferably, the aperture of the first through hole and the aperture of the second through hole are both smaller than the inner diameters of the upper ventilation slot, the first chamber, and the lower ventilation slot.

[0018] In the MEMS element as described above, preferably, both the upper diaphragm and the lower diaphragm are made of conductive materials, or each of the upper diaphragm and the lower diaphragm includes an insulating film having a conductive electrode layer.

[0019] Alternatively, the upper diaphragm and the lower diaphragm each include an insulating film having a conductive region formed by material doping or implantation.

[0020] A MEMS element as described above, wherein preferably, each of the support members is composed of a plurality of concentrically arranged first arc segments, a plurality of the first arc segments are arranged in an annular manner, a plurality of through holes are provided on the counter electrode, a plurality of the first arc segments are respectively accommodated in a plurality of the through holes and are arranged in an annular manner with respect to the counter electrode, and the two ends of each of the first arc segments are respectively connected to the upper diaphragm and the lower diaphragm.

[0021] In the MEMS element as described above, preferably, the shapes of the upper ventilation slot, the first chamber, and the lower ventilation slot are all the same as the shapes of the corresponding first arc segments.

[0022] Compared with the prior art, the first chamber of the present invention is provided with an upper ventilation groove on the upper diaphragm and a lower ventilation groove on the lower diaphragm. The upper ventilation groove is connected to the lower ventilation groove to form a ventilation structure, thereby not reducing the local stiffness of the diaphragm, and at the same time improving the flexibility of the diaphragm and the sensitivity of the microphone. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is an axonometric view of the MEMS element according to the first embodiment of the present invention;

[0024] Figure 2 is a top view of the MEMS element according to the first embodiment of the present invention;

[0025] Figure 3 Schematic diagram of the layout structure of the upper ventilation slots and the lower ventilation slots in the first embodiment provided by the present invention;

[0026] Figure 4 is a top view of the MEMS element according to the second embodiment of the present invention;

[0027] Figure 5 Schematic diagram of the layout structure of the upper ventilation slots and the lower ventilation slots in the second embodiment provided by the present invention;

[0028] Figure 6 Schematic diagram of the layout structure of the upper ventilation slots and the lower ventilation slots according to the third embodiment of the present invention;

[0029] Figure 7 It is a structural schematic diagram of the support member of the present invention.

[0030] Description of reference numerals:

[0031] 10-base, 11-dorsal cavity;

[0032] 20 - diaphragm, 21 - upper diaphragm, 211 - upper ventilation slot, 22 - lower diaphragm, 221 - lower ventilation slot, 23 - accommodation space, 24 - first protrusion, 25 - second protrusion, 26 - first membrane layer, 27 - second membrane layer, 28 - first through hole, 29 - second through hole;

[0033] 30-support member, 31-first arc segment, 32-first chamber;

[0034] 40- Counter electrode. DETAILED DESCRIPTION

[0035] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and are not to be construed as limiting the present invention.

[0036] Example 1

[0037] like Figures 1 to 3 As shown, Figure 1 is an axonometric view of the MEMS element according to the first embodiment of the present invention; Figure 2 is a top view of the MEMS element according to the first embodiment of the present invention; Figure 3 It is a schematic diagram of the layout structure of the upper ventilation slots and the lower ventilation slots in the first embodiment provided by the present invention.

[0038] An embodiment of the present invention provides a MEMS element, including a substrate 10, a diaphragm 20, a plurality of support members 30, and a counter electrode 40, wherein:

[0039] A back cavity 11 passes through the base 10 . Preferably, the inner contour surface of the back cavity 11 is a circular groove structure.

[0040] The diaphragm 20 is connected to the base 10 and covers the back cavity 11. The diaphragm 20 includes an upper diaphragm 21 and a lower diaphragm 22 that are relatively arranged. In this embodiment, the upper diaphragm 21 and the lower diaphragm 22 are both concentrically arranged circular structures. A preset gap is maintained between the upper diaphragm 21 and the lower diaphragm 22 to form an accommodating space 23, and the lower diaphragm 22 is located below the upper diaphragm 21.

[0041] Preferably, the accommodation space 23 is hermetically sealed, and the internal pressure of the accommodation space 23 is less than the external atmospheric pressure. The internal pressure of the accommodation space 23 is less than 0.2 atm, and preferably, the pressure in the accommodation space 23 is equal to 0.1 atm. In some embodiments, the accommodation space 23 is vacuum.

[0042] The counter electrode 40 is disposed in a suspended state within the accommodation space 23. Under normal conditions, there is no contact between the counter electrode 40 and the upper diaphragm 21 and the lower diaphragm 22, and there is no mechanical coupling between the counter electrode 40 and the support member 30. A first capacitor is formed between the upper diaphragm 21 and the counter electrode 40, and a second capacitor is formed between the lower diaphragm 22 and the counter electrode 40. In response to pressure applied to the upper diaphragm 21 and the lower diaphragm 22, the upper diaphragm 21 and the lower diaphragm 22 can move relative to the corresponding counter electrode 40, thereby changing the distance between the upper diaphragm 21 and the lower diaphragm 22 and the corresponding counter electrode 40, which causes the capacitance to change and outputs an electrical signal accordingly.

[0043] Multiple support members 30 are concentrically and spaced apart in the accommodating space 23 and spaced apart from the counter electrode 40. Multiple support members 30 are spaced apart along the radial direction of the diaphragm 20 with the center of the circle of the diaphragm 20 as the center. At least in one of the support members 30, a plurality of first chambers 32 are opened. Preferably, the first chambers 32 are only opened in the support member 30 located at the periphery of the diaphragm 20. In the local area of ​​this support member 30, the opposite ends of the support member 30 are respectively connected to the upper diaphragm 21 and the lower diaphragm 22.

[0044] The function of the support member 30 is to keep the upper diaphragm 21 and the lower diaphragm 22 flat, or at least limit / control the bending / deformation of the upper diaphragm 21 and the lower diaphragm 22 between the support member 30, so as to avoid the upper diaphragm 21 and the lower diaphragm 22 folding against each other when the sealed volume of the accommodating space 23 is at a reduced atmospheric pressure and the outside is at ambient atmospheric pressure.

[0045] The MEMS element has an upper ventilation groove 211 passing through the upper diaphragm 21 corresponding to the first chamber 36, and a lower ventilation groove 221 passing through the lower diaphragm 22 corresponding to the first chamber 36. The upper ventilation groove 211 and the lower ventilation groove 221 are connected via the first chamber 32 to form a ventilation channel. Compared with setting the ventilation channel at the center of the diaphragm 20, this embodiment will not reduce the local stiffness of the diaphragm 20, and at the same time can improve the flexibility of the diaphragm 20, and the microphone sensitivity will be higher.

[0046] Controlling the acoustic impedance through openings in the upper or lower diaphragm 21, 22 allows for shallower, more controlled etching to be used, allowing etching and photolithography to be performed on a more uniform topology, simplifying the process and reducing variability.

[0047] Positioning the first chamber 32 within the support member 30 ensures that the local rigidity of the placement area is not altered, while also providing mechanical support to the edges of the upper ventilation slot 211, the first chamber 32, and the lower ventilation slot 221. This prevents inherent stress within the diaphragm 20 from causing the upper ventilation slot 211, the first chamber 32, and the lower ventilation slot 221 to open, thereby causing the acoustic impedance to deviate from the designed value.

[0048] Furthermore, the upper ventilation groove 211 and the lower ventilation groove 221 are close to the edge of the diaphragm 20, and the upper ventilation groove 211 and the lower ventilation groove 221 are preferably slit-shaped groove bodies. Their length is much greater than their width, which prevents the problem of slit opening due to inherent stress in the film, thereby causing the acoustic impedance to deviate from the design value.

[0049] Continue to refer to Figure 3 As shown, the upper diaphragm 21 and the lower diaphragm 22 are both corrugated structures, and are both made of conductive materials or insulating films including conductive materials or insulating films including conductive materials, and are made of conductive regions formed by material doping or injection. The upper diaphragm 21 includes a plurality of first protrusions 24 protruding toward the accommodating space 23 and spaced apart from each other, and the lower diaphragm 22 includes a plurality of second protrusions 25 protruding toward the accommodating space 23 and spaced apart from each other. The plurality of first protrusions 24 and the plurality of second protrusions 25 are all spaced apart along the radial direction of the diaphragm 20, and the plurality of support members 30, the plurality of first protrusions 24 and the plurality of second protrusions 25 correspond to each other one by one. The two ends of the support member 30 are respectively connected to the first protrusion 24 and the second protrusion 25, the upper ventilation groove 211 is opened on the first protrusion 24, and the lower ventilation groove 221 is opened on the second protrusion 25.

[0050] Preferably, the first protrusion 24 and the second protrusion 25 have the same shape and size to form regular corrugations, thereby evenly distributing the stress on the entire diaphragm 20 and facilitating molding processing. Furthermore, the cross-sectional shape of the first protrusion 24 and the second protrusion 25 in the direction perpendicular to the diaphragm 20 can be rectangular, trapezoidal, or triangular, etc., and the angle of the inclined surface of the first protrusion 24 and the second protrusion 25 is greater than 0° and less than or equal to 90°. Those skilled in the art will appreciate that the cross-sectional shape of the first protrusion 24 and the second protrusion 25 in the direction perpendicular to the diaphragm 20 can be regular or irregular, and this is not limited here.

[0051] The first protrusion 24 and the second protrusion 25 together constitute the corrugation of the diaphragm 20, so that the diaphragm 20 has greater tension and can withstand greater sound pressure. At the same time, the diaphragm 20 has smaller internal stress, the stiffness of the diaphragm 20 is reduced, and the mechanical sensitivity of the MEMS element 200 is effectively improved.

[0052] Continue to refer to Figure 3 As shown, the inner diameter of the upper ventilation slot 211 is larger than the inner diameter of the lower ventilation slot 221. Preferably, the inner diameter of the upper ventilation slot 211 is 6 μm and the inner diameter of the lower ventilation slot 221 is 4 μm to achieve an optimal balance between minimizing resistance variation and column size. Those skilled in the art will appreciate that the inner diameter of the upper ventilation slot 211 can also be set to be smaller than or equal to the inner diameter of the lower ventilation slot 221.

[0053] Reference Figure 7As shown, Figure 7 It is a structural schematic diagram of the support member of the present invention; each support member 30 is composed of a plurality of concentrically arranged first arc segments 31, and a plurality of first arc segments 31 are arranged at intervals in a ring, and a plurality of through holes (not shown) are provided on the counter electrode 40. The first arc segments 31 are respectively accommodated in the plurality of through holes and are spaced apart from the counter electrode 40. The two ends of each first arc segment 31 are respectively connected to the upper diaphragm 21 and the lower diaphragm 22, the top end of the first arc segment 31 is connected to the upper diaphragm 21, and the bottom end of the first arc segment 31 extends through the through hole and is connected to the lower diaphragm 22.

[0054] The cross-section of the first arc segment 31 is an arc structure. The inner diameters of the multiple first arc segments 31 in the same support member 30 are the same. The shapes of the upper ventilation groove 211, the first chamber 32 and the lower ventilation groove 221 are the same as the shapes of the first arc segments 31 corresponding to them. The multiple first arc segments 31 are arranged in a ring-shaped interval. By using a larger first arc segment 31 to support the upper diaphragm 21 and the lower diaphragm 22, the technical problem of requiring a large number of vias to be opened in the electrode 40 is solved, and the design of the electrode 40 is separated from the design of the support member 3. At the same time, the first arc segment 31 is much larger than the small cylinder in the prior art, which makes the column structure with the same aspect ratio much higher, which makes it possible to use a thicker counter electrode 40, allowing a harder structure, which can significantly improve the stability and reliability of the device.

[0055] Continue to refer to Figure 7 As shown, along the radial direction of the diaphragm 20 , the arc length of the first arc segments 31 in the plurality of support members 30 gradually increases. Since there is no need to open a through hole in the gap between two adjacent first arc segments 31 , the stiffness of the electrode 40 is further increased.

[0056] The arc length of the first arc segment 31 in the plurality of supports 30 may increase linearly or nonlinearly, that is, the arc length of the first arc segment 31 gradually changes from the center to the edge of the diaphragm 20 , which is beneficial to improving the stiffness of the electrode 40 .

[0057] Example 2

[0058] Reference Figure 4 and Figure 5 As shown, Figure 3 Schematic diagram of the layout structure of the upper ventilation slots and the lower ventilation slots in the first embodiment provided by the present invention; Figure 4This is a top view of a MEMS element according to Example 2 of the present invention. The portions of the upper and lower diaphragms 21 and 22 corresponding to the support members defining the first chambers each include a first membrane layer 26 and a second membrane layer 27. The first membrane layer 26 is closer to the accommodation space 23 than the second membrane layer 27. The first membrane layer 26 is an insulating film, while the second membrane layer 27 is an electrode layer. This allows the second membrane layer 27 to be positioned where the movement of the diaphragm 20 can be most effectively converted into an electrical signal, thereby improving the microphone's sensitivity.

[0059] The first protrusion 24 is formed on the first membrane layer 26 of the upper diaphragm 21, and the second protrusion 25 is formed on the first membrane layer 26 of the lower diaphragm 22. The MEMS element further includes a first through hole 28 and a second through hole 29 that penetrate the second membrane layer 27 of the upper diaphragm 21 and the second membrane layer 27 of the lower diaphragm, respectively. The first through hole 28, the upper ventilation slot 211, the first chamber 32, the lower ventilation slot 221, and the second through hole 29 are sequentially connected. The aperture of the first through hole 28 is not equal to the aperture of the second through hole 29. Preferably, the aperture of the first through hole 28 and the aperture of the second through hole 29 are both smaller than the inner diameter of the upper ventilation slot 211, the first chamber 32, and the lower ventilation slot 221.

[0060] Reference Figure 4 As shown, in some embodiments, both the first membrane layer 26 and the second membrane layer 27 are circular disc-shaped structures, with the second membrane layer 27 concentrically positioned in the middle of the first membrane layer 26. In this embodiment, the diaphragm 20 is circumferentially connected to the substrate 10, and its deflection is parabolic, reaching its maximum at the center of the diaphragm 20 and decreasing to zero at the edges. Since microphone sensitivity is determined by the ratio of capacitance to pressure, positioning the second membrane layer 27 in the middle of the diaphragm 20, where it moves most violently, and omitting the second membrane layer 27 at the edges of the diaphragm 20, can reduce parasitic capacitance between the upper and lower diaphragms 21, 22, thereby improving microphone sensitivity.

[0061] Example 3

[0062] The difference between this embodiment and the first embodiment is that the upper diaphragm 21 and the lower diaphragm 22 are both planar structures. Figure 6 As shown, Figure 6 2 is a schematic diagram of the layout structure of the upper ventilation slots and the lower ventilation slots of the third embodiment provided by the present invention. The size relationship between the upper ventilation slots 211 and the lower ventilation slots 221 can refer to that shown in the first embodiment and will not be repeated here.

[0063] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present invention, but the scope of implementation of the present invention is not limited to what is shown in the drawings. Any changes made in accordance with the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which do not exceed the spirit covered by the description and drawings, should be within the scope of protection of the present invention.

Claims

1. A MEMS element, comprising: a substrate, a back cavity passing through the substrate; a diaphragm connected to the substrate and covering the back cavity, the diaphragm comprising an upper diaphragm and a lower diaphragm arranged opposite to each other, with a receiving space formed between the upper diaphragm and the lower diaphragm; a counter electrode, disposed in the accommodation space; a plurality of concentric and spaced apart support members, disposed between the upper diaphragm and the lower diaphragm and spaced apart from the counter electrode, wherein opposite ends of the support members are respectively connected to the upper diaphragm and the lower diaphragm, and a plurality of first chambers are defined in at least one of the support members; Its characteristics are: The MEMS element has an upper ventilation slot extending through the upper diaphragm corresponding to the first chamber, and a lower ventilation slot extending through the lower diaphragm corresponding to the first chamber, wherein the upper ventilation slot, the first chamber, and the lower ventilation slot are in communication; The upper diaphragm includes several first protrusions protruding toward the accommodating space and spaced apart from each other, and the lower diaphragm includes several second protrusions protruding toward the accommodating space and spaced apart from each other. The several support members, the several first protrusions and the several second protrusions are all in one-to-one correspondence, and the two ends of the support member are respectively connected to the first protrusion and the second protrusion, the upper ventilation groove is opened on the first protrusion, and the lower ventilation groove is opened on the second protrusion.

2. The MEMS element according to claim 1, wherein: The first chamber is only opened in the supporting member located at the periphery of the diaphragm.

3. The MEMS element according to any one of claims 1 to 2, characterized in that: The inner diameter of the upper ventilation groove is greater than the inner diameter of the lower ventilation groove.

4. The MEMS element according to any one of claims 1 to 2, wherein: The inner diameter of the upper ventilation groove is smaller than the inner diameter of the lower ventilation groove.

5. The MEMS element according to claim 1 or 2, wherein: The parts of the upper diaphragm and the lower diaphragm corresponding to the support member in which the first chambers are opened both include a first membrane layer and a second membrane layer, the first membrane layer is closer to the accommodating space than the second membrane layer, the first protrusion is formed on the first membrane layer of the upper diaphragm, and the second protrusion is formed on the first membrane layer of the lower diaphragm, and the MEMS element also includes a first through hole and a second through hole respectively penetrating the second membrane layer of the upper diaphragm and the second membrane layer of the lower diaphragm, the first through hole, the upper ventilation groove, the first chamber, the lower ventilation groove and the second through hole are connected in sequence, and the aperture of the first through hole is not equal to the aperture of the second through hole.

6. The MEMS element according to claim 5, wherein: The apertures of the first through hole and the second through hole are both smaller than the inner diameters of the upper ventilation slot, the first chamber, and the lower ventilation slot.

7. The MEMS element according to claim 1, wherein: The upper diaphragm and the lower diaphragm are both made of conductive materials, or the upper diaphragm and the lower diaphragm each include an insulating film with a conductive electrode layer, or the upper diaphragm and the lower diaphragm each include an insulating film with a conductive region formed by material doping or injection.

8. The MEMS element according to claim 1, wherein: Each of the supporting members is composed of a plurality of concentrically arranged first arc segments, and the plurality of first arc segments are arranged in an annular manner. A plurality of through holes are provided on the counter electrode, and the plurality of first arc segments are respectively accommodated in the plurality of through holes and are arranged in an annular manner with respect to the counter electrode. The two ends of each first arc segment are respectively connected to the upper diaphragm and the lower diaphragm.

9. The MEMS element according to claim 8, wherein: The shapes of the upper ventilation slot, the first chamber, and the lower ventilation slot are all the same as the shapes of the corresponding first arc segments.

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