A MEMS condenser microphone

Abstract

This invention discloses a MEMS capacitive microphone, comprising a substrate, a support, and a diaphragm, wherein: the diaphragm is supported above the substrate by the support, and the substrate, the support, and the diaphragm form a vacuum cavity; the side of the diaphragm near the vacuum cavity is connected to an electrostatic clutch via a connecting rod; the electrostatic clutch is connected to a capacitive sensing structure. Compared with the prior art, the advantage of this invention is that it allows the microphone to operate under a wide range of atmospheric pressures that customers may expect. This is achieved electrostatically in a purely passive manner, which is advantageous over other designs that require complex electronics and active control. Since only small AC disturbances of the rotor need to be considered, without considering DC changes in rotor position, the diaphragm and sensing structure are physically decoupled, thereby simplifying the design of the sensing structure.

Description

Technical Field

[0001] This invention relates to the field of microphone technology, and in particular to a MEMS condenser microphone. Background Technology

[0002] Currently, all commercially available MEMS microphones have a back cavity behind the diaphragm. This is a semi-sealed air volume that undergoes compression and expansion when an input sound wave is present. For a given package size, this back cavity is necessary to allow the diaphragm to move under external pressure waves. However, this back cavity is currently the largest source of acoustic noise and therefore the largest acoustic signal-to-noise ratio (SNR) limiter in the microphone. The lower the volume behind it, the higher the acoustic noise emanating from it. Therefore, unless the package size is made very large, it is impossible to achieve a high SNR microphone of approximately 74 dB or higher. If a vacuum is used instead of the back cavity, and the sensing portion of the MEMS is contained within the vacuum, not only can the back cavity noise be effectively eliminated, but also the damped noise associated with diaphragm movement (such as backplate noise) can be eliminated. The only way to achieve a very high SNR in a common or smaller package is to make the back volume a vacuum.

[0003] There are two major challenges to this type of vacuum back cavity microphone: (1) a pressure difference of 1 atm between air and vacuum can cause a normal diaphragm to collapse, thus requiring a very rigid diaphragm, which results in very low sensitivity; (2) significant changes in ambient pressure cause DC offset changes in diaphragm displacement, and conventional rotor-stator designs do not work.

[0004] Meanwhile, existing microphones require a cavity, which is one of the largest noise sources in commercially available microphones. This limits the signal-to-noise ratio (SNR) unless a very large package size is used, which is not feasible for mobile applications. Within conventional package sizes, it is impossible to achieve a very high microphone SNR, such as 80 dB, unless a vacuum cavity is used.

[0005] Using a vacuum or low-pressure chamber, sealed by a thin membrane facing the atmosphere, presents a fundamental measurement challenge. The atmospheric pressure varies by approximately 100 kPa, depending on the user and the environment in which the device operates. In addition to this slow, direct-current pressure change, the device also needs to measure audio pressure signals on the order of 1 Pa.

[0006] One solution in the prior art involves coupling between the atmosphere-facing membrane and the rotor section of the sensing device, which is "on" for AC audio signals and "off" for low-frequency or DC changes in atmospheric pressure. This clutch-like coupling behavior can be achieved through frequency-dependent electrostatic forces. The electrostatic clutch in this invention is designed to couple AC sound pressure signals between the rotor and stator, but not to couple any force for slow "DC" changes in atmospheric pressure, which typically alter the central deformation of the atmosphere-facing membrane in the micrometer range. For the DC pressure range, the stiffness between the rotor and stator should be zero or minimal, while the stiffness for AC audio pressure should be high. Summary of the Invention

[0007] The purpose of this invention is to provide a MEMS condenser microphone to solve the technical problems in the prior art, allowing the microphone to operate under a wide range of atmospheric pressures that customers may expect.

[0008] This invention provides a MEMS capacitive microphone, comprising a substrate, a support, and a diaphragm, wherein:

[0009] The diaphragm is supported above the substrate by a support portion, and the substrate, the support portion, and the diaphragm form a vacuum cavity;

[0010] The side of the diaphragm closest to the vacuum chamber is connected to an electrostatic clutch via a connecting rod;

[0011] The electrostatic clutch is connected to a capacitance sensing structure.

[0012] In the MEMS capacitive microphone described above, preferably, the electrostatic clutch includes a high-impedance node electrode array as the first component of the electrostatic clutch, and a passage is formed between two of the high-impedance node electrode arrays.

[0013] The bias electrode array, as the second component of the electrostatic clutch, is reciprocating within the passageway to generate an electrostatic force between the bias electrode array and the high-impedance node electrode array.

[0014] In the MEMS condenser microphone described above, preferably, the high-impedance node electrode array includes a plurality of high-impedance node electrodes and a grounding element, an insulating silicon oxide layer is disposed between adjacent high-impedance node electrodes, and the grounding element is electrically connected to the plurality of high-impedance node electrodes and remains grounded.

[0015] In the MEMS capacitive microphone described above, preferably, the high-impedance node electrode comprises a first conductive polysilicon layer, a resistive bridge layer, and a second conductive polysilicon layer. The first conductive polysilicon layer is electrically connected to the second conductive polysilicon layer through the resistive bridge layer. The grounding element is electrically connected to several second conductive polysilicon layers and remains grounded. The electrostatic force between the bias electrode array and the high-impedance node electrode array has a frequency dependence similar to that of a high-pass filter, wherein the low-frequency cutoff is determined by the resistance of the resistive bridge layer.

[0016] In the MEMS capacitive microphone described above, preferably, within each bias electrode array, two adjacent bias electrodes among the plurality of bias electrodes have opposite polarities and are connected by an insulating mechanical support.

[0017] In the MEMS condenser microphone described above, preferably, each bias electrode array further includes two grounded shielding electrodes disposed at both ends of each of the plurality of bias electrode arrays. This is to reduce stray fields from the bias electrodes and increase the force between the two clutch components.

[0018] In the MEMS capacitive microphone described above, preferably, the electrostatic clutch further includes a first connecting portion and a second connecting portion, one end of the first connecting portion is connected to the connecting rod, and the other end of the first connecting portion is connected to a plurality of the bias electrode arrays.

[0019] The second connection part is provided in two parts, and the two second connection parts are symmetrically arranged on opposite sides of the first connection part. One end of each second connection part is provided with a plurality of high impedance node electrode arrays, and the other end of each second connection part is connected to the capacitive sensing structure.

[0020] The high-impedance node electrode arrays and the bias electrode arrays are all arranged in a comb-like pattern. The high-impedance node electrode arrays and the bias electrode arrays are spatially separated and intersect each other.

[0021] The capacitive sensing structure includes a first lever, a first support, a first moving sensing electrode, and a first stationary sensing electrode. The lever is pivotally connected to the first support. One end of the first lever is connected to the second connecting part, and the other end of the first lever is connected to the first moving sensing electrode. The first stationary sensing electrode is opposite to the first moving sensing electrode.

[0022] In the MEMS condenser microphone described above, preferably, the electrostatic clutch further includes a third connecting part and a fourth connecting part, one end of the third connecting part is connected to the connecting rod, and the other end of the fourth connecting part is connected to a plurality of the bias electrode arrays.

[0023] The fourth connection part is provided in two parts, and the two fourth connection parts are symmetrically arranged on opposite sides of the third connection part. A plurality of high impedance node electrode arrays are connected between the two fourth connection parts, and the other end of each fourth connection part is connected to the capacitive sensing structure.

[0024] The high-impedance node electrode arrays and the bias electrode arrays are all arranged in a comb-like pattern. The high-impedance node electrode arrays and the bias electrode arrays are spatially separated and intersect each other.

[0025] The capacitive sensing structure includes a second lever, a second support, a curved slit, a second sensing moving electrode, and a second sensing stationary electrode. The lever body is pivotally connected to the second support. One end of the second lever is connected to the fourth connecting part, and the other end of the second lever is connected to the second sensing moving electrode. The second sensing stationary electrode is opposite to the second sensing moving electrode. The curved slit is located at one end of the second lever near the fourth connecting part.

[0026] In the MEMS condenser microphone described above, preferably, the electrostatic clutch includes a fifth connecting portion, a first suspension beam, and a first suspension plate, wherein:

[0027] One end of the fifth connecting part is connected to the connecting rod, and the other end of the fifth connecting part is connected to a plurality of the high-impedance node electrode array;

[0028] The first suspension plate is suspended and supported in the vacuum cavity by the first suspension beam on both sides. A plurality of bias electrode arrays are spaced apart on the first suspension plate. A first gap and a second gap are formed on the opposite sides of the bias electrode arrays on the first suspension plate, respectively.

[0029] A plurality of the high-impedance node electrode arrays correspond one-to-one with a plurality of the first gaps, and each extends into the first gap;

[0030] The capacitance sensing structure includes a third sensing electrode, a plurality of the third sensing electrodes are spaced apart on the substrate, and the plurality of the third sensing electrodes correspond one-to-one with a plurality of the second gaps, each extending into the second gap.

[0031] In a MEMS capacitive microphone as described above, preferably, the third sensing static electrode includes a first portion and a second portion, the first portion extending into the second gap, and the second portion protruding from the second gap and extending along the length direction of the first suspension plate.

[0032] In the MEMS condenser microphone described above, preferably, the electrostatic clutch includes a sixth connecting portion, a second suspension beam, and a second suspension plate, wherein:

[0033] One end of the sixth connecting part is connected to the connecting rod, and the other end of the sixth connecting part is connected to a plurality of the bias electrode array;

[0034] The second suspension plate is suspended and supported in the vacuum cavity by the second suspension beam on both sides. A plurality of high impedance node electrode arrays are spaced apart on the second suspension plate, and a third gap is formed between adjacent high impedance node electrode arrays.

[0035] Each of the bias electrode arrays corresponds to one of the third gaps and extends into the third gap;

[0036] The capacitive sensing structure includes a fourth moving sensing electrode and a fourth stationary sensing electrode. The fourth moving sensing electrode is fixed to the bottom of the suspension plate, and the fourth stationary sensing electrode is spaced apart on the substrate. The fourth stationary sensing electrode is opposite to the fourth moving sensing electrode.

[0037] In the MEMS condenser microphone described above, preferably, the electrostatic clutch includes a seventh connecting portion, a third suspension beam, and a third suspension plate, wherein:

[0038] One end of the seventh connecting part is connected to the connecting rod, and the other end of the seventh connecting part is connected to a plurality of the bias electrode array;

[0039] The third suspension plate is suspended and supported in the vacuum cavity by the third suspension beam on both sides. The third suspension plate is provided with a receiving cavity and a plurality of high impedance node electrode arrays. The plurality of high impedance node electrode arrays are spaced apart on opposite sides of the receiving cavity, and a fourth gap is formed between adjacent high impedance node electrode arrays.

[0040] Each of the bias electrode arrays corresponds to one of the fourth gaps and extends into the fourth gap;

[0041] The capacitive sensing structure includes a fifth sensing active electrode and a fifth sensing static electrode housed within the receiving cavity. Both ends of a plurality of the fifth sensing active electrodes are fixed to the wall of the receiving cavity. The fifth sensing static electrode is supported on the substrate by a bracket. The fifth sensing static electrode and the fifth sensing active electrode are spatially separated and intersect each other.

[0042] In the MEMS condenser microphone described above, preferably, the bias electrode array is connected to the diaphragm, the diaphragm is located within the passage channel, and can reciprocate within the passage channel along the arrangement direction of the bias electrodes.

[0043] In the MEMS condenser microphone described above, preferably, the electrostatic clutch includes an eighth connecting portion, a fourth suspension beam, and a fourth suspension plate, wherein:

[0044] One end of the eighth connecting part is connected to the connecting rod, and the other end of the eighth connecting part is connected to a plurality of the high-impedance node electrode array;

[0045] The fourth suspension plate is suspended and supported in the vacuum cavity by the fourth suspension beam on both sides. A plurality of bias electrode arrays are spaced apart on the fourth suspension plate. The opposite sides of the bias electrode arrays form a fifth gap and a sixth gap on the fourth suspension plate, respectively.

[0046] Each of the high-impedance node electrode arrays corresponds one-to-one with a number of the fifth gaps, and each extends into the fifth gap;

[0047] Several fifth gaps are evenly distributed on opposite sides of the sixth gap, and a light reflector is provided in the sixth gap;

[0048] The substrate is equipped with a light emitter and a light detector.

[0049] Compared to existing technologies, the advantage of this invention is that it allows the microphone to operate under a wide range of atmospheric pressures that customers may expect. This is achieved electrostatically in a purely passive manner, which is advantageous over other designs that require complex electronics and active control. Furthermore, the design of the sensing structure is simplified because only minute AC disturbances of the rotor need to be considered, without taking into account DC variations in rotor position. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of an electrostatic clutch consisting of a grounded high-impedance node electrode array and a single bias electrode.

[0051] Figure 2This is a schematic diagram of a high-impedance node electrode array deposited using silicon deposition technology.

[0052] Figure 3 This is a top view of the electrical connections of one layer of a high-impedance node electrode array;

[0053] Figure 4 This is a schematic diagram of an electrostatic clutch with multiple bias electrodes having alternating polarities.

[0054] Figure 5 This is a schematic diagram of an electrostatic clutch with a grounded shield electrode at the end of the bias electrode array to enhance rigidity.

[0055] Figure 6a , 6b 6c and 6d are schematic diagrams of the first structure of the MEMS capacitor microphone of the present invention, wherein the electrostatic clutch is part of a hinged cantilever transducer with different combinations of atmospheric pressure and sound pressure.

[0056] Figure 7 This is a top view of the first structure of the MEMS capacitive microphone of the present invention;

[0057] Figure 8a and 8b This is a schematic diagram of the structure of the second type of MEMS capacitive microphone of the present invention;

[0058] Figure 9 This is a top view of the second type of MEMS capacitive microphone of the present invention;

[0059] Figure 10 This is a schematic diagram of the third type of MEMS capacitive microphone of the present invention;

[0060] Figure 11 This is a top view of the third type of MEMS capacitive microphone of the present invention;

[0061] Figure 12 This is a schematic diagram of the fourth type of MEMS capacitive microphone of the present invention;

[0062] Figure 13 This is a schematic diagram of the fifth type of MEMS capacitive microphone of the present invention;

[0063] Figure 14 This is a schematic diagram of the sixth type of MEMS capacitive microphone of the present invention;

[0064] Figure 15 This is another schematic diagram of the high-impedance node electrode array of the present invention;

[0065] Figure 16This is a schematic diagram of the seventh type of MEMS capacitive microphone of the present invention;

[0066] Figure 17 This is a top view of the seventh structure of the MEMS capacitive microphone of the present invention;

[0067] Figure 18 This is a schematic diagram of the eighth structure of the MEMS capacitor microphone of the present invention.

[0068] Explanation of reference numerals in the attached figures:

[0069] 100-Electrostatic Clutch;

[0070] 101-High impedance node electrode array, 1011-High impedance node electrode, 1012-Grounding element, 1013-Insulating silicon oxide layer, 1014-First conductive polycrystalline silicon layer, 1015-Resistor bridge layer, 1016-Second conductive polycrystalline silicon layer, 1017-Tune resistor material, 1018-Polycrystalline silicon conductive material.

[0071] 102-Bias electrode array, 1021-Bias electrode, 1022-Insulating mechanical support, 1023-Electrically shielded electrode;

[0072] 103-First connecting part, 104-Second connecting part, 105-Third connecting part, 106-Fourth connecting part, 107-Fifth connecting part, 108-First suspension beam, 109-First suspension plate, 110-Sixth connecting part, 111-Second suspension beam, 112-Second suspension plate, 113-Seventh connecting part, 114-Third suspension beam, 115-Third suspension plate, 116-Receiving cavity; 117-Eighth connecting part, 118-Fourth suspension beam, 119-Fourth suspension plate;

[0073] 200-MEMS condenser microphone, 201-substrate, 202-support, 203-diaphragm, 204-vacuum cavity, 205-connecting rod;

[0074] 300-Capacitive sensing structure, 301-First lever, 302-First support, 303-First sensing moving electrode, 304-First sensing stationary electrode, 305-Second lever, 306-Second support, 307-Curved slit, 308-Second sensing moving electrode, 309-Second sensing stationary electrode, 310-Third sensing stationary electrode, 3101-First part, 3102-Second part, 311-Fourth sensing moving electrode, 312-Fourth sensing stationary electrode, 313-Fifth sensing moving electrode, 314-Fifth sensing stationary electrode, 315-Light reflector, 316-Light emitter, 317-Photodetector. Detailed Implementation

[0075] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0076] To better explain this embodiment, a three-dimensional coordinate system is established, in which the XY plane is considered to be parallel to the silicon die surface where the MEMS layer is deposited, and the Z axis is considered to be perpendicular to this plane.

[0077] like Figures 1 to 5 As shown, an embodiment of the present invention provides an electrostatic clutch 100, which is designed to couple an AC sound pressure signal between the rotor and stator, but not to couple any force from slowly changing 'DC' atmospheric pressure, which typically alters the central deformation of the atmospheric surface on the diaphragm 203 in the micrometer range. For the DC voltage range, the stiffness between the rotor and stator should be zero or minimal. The electrostatic clutch 100 includes:

[0078] The high-impedance node electrode array 101, as the first component of the electrostatic clutch 100, typically acts as the clutch stator. A passageway is formed between two high-impedance node electrode arrays 101. In this embodiment, the high-impedance node electrode array 101 preferably includes a plurality of high-impedance node electrodes 1011 and a grounding element 1012. The more high-impedance node electrodes 1011 there are, the higher the performance. However, for embodiments with z-axis rotor displacement, the number of high-impedance node electrodes 1011 is actually limited by process constraints. An insulating silicon oxide layer 1013 is provided between adjacent high-impedance node electrodes 1011, and the grounding element 1012 is electrically connected to a plurality of high-impedance node electrodes 1011 and remains grounded.

[0079] The bias electrode array 102, as the second component of the electrostatic clutch 100, typically functions as the clutch rotor. However, those skilled in the art will recognize that the high-impedance node electrode array 101 can also function as the clutch rotor, while the bias electrode array 102 functions as the clutch stator; this is not a limitation. One end of the bias electrode array 102 is connected to the diaphragm 203. As the diaphragm 203 shifts, the other end of the bias electrode array 102 can reciprocate within the passageway, thereby generating an electrostatic force between the bias electrode array 102 and the high-impedance node electrode array 101.

[0080] The electrostatic clutch 100 is effectively "open" at audio frequencies and effectively "closed" at low frequencies. This clutch acts as an RC high-pass filter that couples the AC motion of the diaphragm 203 corresponding to the audio signal, but filters out the slow motion of the diaphragm 203 caused by slow changes in atmospheric pressure, typically in the range of 0.5-1 atm, which may occur, for example, with changes in weather, altitude, or the interior of the aircraft.

[0081] When the bias electrode array 102 is stationary or moves at a frequency below the cutoff frequency, charge flows freely from or onto the surface of the high-impedance node electrode 1011. This means that when the bias electrode array 102 moves slowly relative to the high-impedance node electrode array 101, at a frequency below the cutoff value, there is no force coupling or interaction between the clutch stator and the clutch rotor. In this case, the clutch stiffness is approximately zero. However, when the clutch rotor moves at a frequency above the cutoff frequency, the charge induced in the hinge by the bias electrode 1021 is trapped. Typically, the size of each high-impedance node electrode 1011 will be much smaller than that of the bias electrode 1021, resulting in a significant restoring force on the AC displacement of the clutch rotor. This corresponds to a significant coupling stiffness. Therefore, the filter is achieved through frequency-dependent electrostatic stiffness between the atmosphere-facing diaphragm 203 and the rotor portion of the capacitive sensing structure 300.

[0082] Reference Figure 2 and Figure 3 As shown, the high-impedance node electrode 1011 includes a first conductive polysilicon layer 1014, a resistive bridge layer 1015, and a second conductive polysilicon layer 1016. The first conductive polysilicon layer 1014 is electrically connected to the second conductive polysilicon layer 1016 through the resistive bridge layer 1015. The grounding element 1012 is electrically connected to several of the second conductive polysilicon layers 1016 and remains grounded. The resistive bridge layer 1015 connecting each layer to ground can be made of doped polysilicon, a material used in diode manufacturing, or a Schottky material. The resistivity of this material and the resistive bridge layer 1015 can be used to adjust the roll-off frequency. The roll-off frequency determines the frequency at which the clutch no longer drives the sensor sensing part. The roll-off frequency is proportional to 1 / RC, where R is the resistance of the resistive bridge layer 1015 and C is the capacitance between a single high-impedance node electrode 1011 and the bias electrode 1021 it faces.

[0083] Reference Figure 15As shown, the high-impedance node electrode array 101 can also be composed of a tuned resistive material 1017 and a polysilicon conductive material 1018, with the polysilicon conductive material 1018 grounded. This has the major advantage of avoiding many process layers. For the high-impedance node electrode array 101, in this case, the resistivity of the tuned resistive material 1017 will determine the frequency at which charge is locally trapped when the bias electrode array 102 moves, rather than the resistance of a single resistive bridge layer determining the roll-off frequency. The grounding of this material can be provided by a polysilicon layer or other conductive material with a resistivity lower than that of the tuned resistive material 1017. The polysilicon conductive material 1018 has an interface with the tuned resistive material 1017 on the z-axis and aims to achieve zero potential along the z-axis length of the tuned resistive material 1017 on the surface not facing the bias electrode. Additionally, an insulating layer that eliminates the effect of reducing the z-axis stiffness of the clutch can also be included.

[0084] Reference Figure 4 and Figure 5 As shown, the bias electrode array 102 includes a plurality of bias electrodes 1021 arranged with alternating polarities. Adjacent bias electrodes 1021 have opposite polarities and are connected by an insulating mechanical support 1022. The bias electrode array 102 also includes electrically shielded electrodes 1023 located at both ends of the bias electrode array 102. This minimizes the electric field of the bias electrodes 1021 passing through the channel between the two high-impedance node electrode arrays 101. Stray electric fields are the source of non-zero DC forces between the clutch rotor and stator within their DC displacement range. A non-zero DC force drives the sensing part of the sensor when there is no audio signal, which is undesirable. The electrically shielded electrodes 1023 effectively reduce the DC force to almost zero over a large distance range of micrometers required for atmospheric pressure changes.

[0085] Based on the electrostatic clutch 100 described above, this embodiment also provides a MEMS capacitive microphone 200, including a substrate 201, a support portion 202, and a diaphragm 203, wherein: the diaphragm 203 is supported above the substrate 201 by the support portion 202, and the substrate 201, the support portion 202, and the diaphragm 203 form a vacuum cavity 204; the side of the diaphragm 203 near the vacuum cavity 204 is connected to the electrostatic clutch 100 via a connecting rod 205; the electrostatic clutch 100 is connected to a capacitive sensing structure 300.

[0086] The substrate 201 can be made of monocrystalline silicon or other materials known to those skilled in the art, and the support portion 202 and the diaphragm 203 supported on the substrate 201 by the support portion 202 can be formed by a layer-by-layer deposition, patterning, and sacrificial process. If necessary, an insulating layer is also provided between the support portion 202 and the substrate 201, which will not be described in detail here.

[0087] The vacuum chamber 204 can be sealed, for example, by low-pressure plasma-enhanced chemical vapor deposition (PECVD) at 200-350°C. This MEMS process is common knowledge to those skilled in the art and will not be described in detail here. Preferably, the vacuum chamber 204 has a pressure less than 1 kPa, which makes the viscosity of the residual gas in the vacuum chamber 204 significantly lower than the viscosity of air at standard pressure.

[0088] Because a vacuum cavity 204 with a pressure lower than atmospheric pressure is formed between the diaphragm 203 and the substrate 201, the diaphragm 203 will undergo static deflection under atmospheric pressure and without sound pressure. That is, the diaphragm 203 will statically deflect towards the substrate 201, and charges will freely flow from or onto the surface of the high-impedance node electrode 1011. This means that when the bias electrode array 102 moves slowly relative to the high-impedance node electrode array 101, the frequency is below the cutoff value, there is no force coupling or interaction between the clutch stator and the clutch rotor, and the electrical signal output by the capacitor structure in the capacitive sensing structure 300 remains unchanged. When the diaphragm 203 moves at a frequency higher than the cutoff frequency, the electrostatic clutch 100 generates electrostatic force, driving the capacitor structure to output a changing electrical signal.

[0089] This invention provides MEMS condenser microphones 200 with various structural forms. It is understood that those skilled in the art can deduce more modified embodiments based on the provided microphone structure, which are not limited here.

[0090] Reference Figure 6a , 6b 6c, 6d and Figure 7 As shown, the first structure of the present invention, MEMS capacitive microphone 200, is displayed. The electrostatic clutch 100 and the capacitive sensing structure 300 are both disposed in the vacuum cavity 204. The electrostatic clutch 100 also includes a first connecting part 103 and a second connecting part 104. One end of the first connecting part 103 is connected to the connecting rod 205, and the other end of the first connecting part 103 is connected to a plurality of bias electrode arrays 102. The plurality of bias electrode arrays 102 constitute the rotor of the electrostatic clutch 100. The displacement of the diaphragm 203 will cause the bias electrode arrays 102 to shift synchronously.

[0091] Two second connection portions 104 are provided, and the two second connection portions 104 are symmetrically arranged on opposite sides of the first connection portion 103. One end of each second connection portion 104 is provided with a plurality of high-impedance node electrode arrays 101, and the other end of each second connection portion 104 is connected to the capacitive sensing structure 300. The plurality of high-impedance node electrode arrays 101 constitute the stator of the electrostatic clutch 100.

[0092] The high-impedance node electrode arrays 101 and the bias electrode arrays 102 are arranged in a comb-like pattern, spatially separated, and intersecting each other. This structure provides relatively large displacement, reduces acoustic noise, and provides high sensitivity.

[0093] The capacitive sensing structure 300 includes a first lever 301, a first support portion 302, a first sensing moving electrode 303, and a first sensing stationary electrode 304. The rod of the first lever 301 is pivotally connected to the first support portion 302. One end of the first lever 301 is connected to the second connecting portion 104, and the other end of the first lever 301 is connected to the first sensing moving electrode 303. The first sensing stationary electrode 304 is opposite to the first sensing moving electrode 303. The first sensing stationary electrode 304 and the first sensing moving electrode 303 constitute a capacitor structure that can output a changing electrical signal.

[0094] Vibration of the diaphragm 203 activates the electrostatic clutch 100, generating electrostatic force. The clutch stator shifts under the alternating displacement of the clutch rotor, thereby activating one end of the first lever 301. The first lever 301 increases mechanical sensitivity by amplifying the displacement of the electrostatic clutch 100. The first sensing electrode 303 on the first lever 301 moves synchronously, changing the area between the first sensing stationary electrode 304 and the first sensing moving electrode 303, allowing the capacitor structure to output a changing electrical signal. The working principle of the capacitor structure is common knowledge to those skilled in the art.

[0095] Reference Figure 8a , 8b as well as Figure 9 The second type of MEMS capacitor microphone 200 includes an electrostatic clutch 100 that further includes a third connecting part 105 and a fourth connecting part 106. One end of the third connecting part 105 is connected to the connecting rod 205, and the other end of the fourth connecting part 106 is connected to a plurality of bias electrode arrays 102. The plurality of bias electrode arrays 102 constitute the rotor of the electrostatic clutch 100. The displacement of the diaphragm 203 will cause the bias electrode arrays 102 to shift synchronously.

[0096] Two fourth connection portions 106 are provided, symmetrically arranged on opposite sides of the third connection portion 105. A plurality of high-impedance node electrode arrays 101 are connected between the two fourth connection portions 106. The other end of each fourth connection portion 106 is connected to the capacitive sensing structure 300. The plurality of high-impedance node electrode arrays 101 constitute the stator of the electrostatic clutch 100. The difference between the second type of MEMS capacitive microphone 200 and the first type of MEMS capacitive microphone 200 is that the two second connection portions 104 of the first type of MEMS capacitive microphone 200 are independently provided with high-impedance node electrode arrays 101, while the two fourth connection portions 106 of the second type of MEMS capacitive microphone 200 share the high-impedance node electrode arrays 101.

[0097] The high-impedance node electrode arrays 101 and the bias electrode arrays 102 are arranged in a comb-like pattern. The high-impedance node electrode arrays 101 and the bias electrode arrays 102 are spatially separated and intersect each other. This structure provides relatively large displacement, reduces acoustic noise, and provides high sensitivity.

[0098] The capacitive sensing structure 300 includes a second lever 305, a second support 306, a curved slit 307, a second moving sensing electrode 308, and a second stationary sensing electrode 309. The lever 305 is pivotally connected to the second support 306. One end of the second lever 305 is connected to the fourth connecting part 106, and the other end is connected to the second moving sensing electrode 308. The second stationary sensing electrode 309 is opposite to the second moving sensing electrode 308. The second stationary sensing electrode 309 and the second moving sensing electrode 308 constitute a capacitor structure capable of outputting a changing electrical signal. The curved slit 307 is located at one end of the second lever 305 near the fourth connecting part 106. In this configuration, the clutch stator moves only along the Z-axis without rotating, and the lever is activated by the curved slit 307. The second moving sensing electrode 308 on the second lever 305 moves synchronously, causing a change in the facing area between the second stationary sensing electrode 309 and the moving sensing electrode 308, thus enabling the capacitor structure to output a changing electrical signal. The working principle of capacitor structure is common knowledge to those skilled in the art.

[0099] Reference Figure 10 and Figure 11 As shown, this is a third type of MEMS capacitor microphone 200. The electrostatic clutch 100 includes a fifth connecting part 107, a first suspension beam 108, and a first suspension plate 109, wherein:

[0100] One end of the fifth connecting part 107 is connected to the connecting rod 205, and the other end of the fifth connecting part 107 is connected to a plurality of high-impedance node electrode arrays 101. The plurality of high-impedance node electrode arrays 101 constitute the rotor of the electrostatic clutch 100. The displacement of the diaphragm 203 will cause the high-impedance node electrode arrays 101 to shift synchronously.

[0101] The first suspension plate 109 is suspended and supported in the vacuum cavity 204 by the first suspension beam 108 on both sides. A plurality of bias electrode arrays 102 are spaced apart on the first suspension plate 109. A first gap and a second gap are formed on the opposite sides of the bias electrode arrays 102 on the first suspension plate 109, respectively. The plurality of bias electrodes 1021 simultaneously constitute the stator of the electrostatic clutch 100 and the sensing moving electrode of the capacitive sensing structure 300.

[0102] A plurality of the high-impedance node electrode arrays 101 correspond one-to-one with a plurality of the first gaps, and extend into the first gaps respectively.

[0103] The capacitance sensing structure 300 includes a third sensing electrode 310, a plurality of the third sensing electrodes 310 being spaced apart on the substrate 201, and the plurality of the third sensing electrodes 310 corresponding one-to-one with a plurality of the second gaps, each extending into the second gap.

[0104] Vibration of the diaphragm 203 activates the electrostatic clutch 100, generating electrostatic force. The clutch stator shifts under the alternating displacement of the clutch rotor, causing a change in the area between the third sensing static electrode 310 and the bias electrode 1021. This allows the capacitor structure to output a changing electrical signal. The working principle of the capacitor structure is common knowledge to those skilled in the art.

[0105] Reference Figure 12 As shown, this is a schematic diagram of the fourth type of MEMS capacitive microphone 200 of the present invention. The structural difference between this fourth and third type of MEMS capacitive microphone 200 lies in that the third sensing static electrode 310 includes a first portion 3101 and a second portion 3102. The first portion 3101 extends into the second gap, and the second portion 3102 protrudes from the second gap and extends along the length of the first suspension plate 109. The second portion 3102 has a parallel plate structure, which maximizes the detection capacitance or allows for higher sensitivity.

[0106] Reference Figure 13 As shown, this is a schematic diagram of the fifth type of MEMS capacitor microphone 200 of the present invention. The electrostatic clutch 100 includes a sixth connecting part 110, a second suspension beam 111, and a second suspension plate 112, wherein:

[0107] One end of the sixth connecting part 110 is connected to the connecting rod 205, and the other end of the sixth connecting part 110 is connected to a plurality of bias electrode arrays 102. The plurality of bias electrode arrays 102 constitute the rotor of the electrostatic clutch 100. The displacement of the diaphragm 203 will cause the bias electrode arrays 102 to shift synchronously.

[0108] The two sides of the second suspension plate 112 are suspended and supported in the vacuum cavity 204 by the second suspension beam 111. A plurality of high-impedance node electrode arrays 101 are spaced apart on the second suspension plate 112, and a third gap is formed between adjacent high-impedance node electrode arrays 101. The plurality of high-impedance node electrode arrays 101 constitute the stator of the electrostatic clutch 100.

[0109] Each of the bias electrode arrays 102 corresponds to one of the third gaps and extends into the third gap.

[0110] The capacitance sensing structure 300 includes a fourth sensing moving electrode 311 and a fourth sensing stationary electrode 312. The fourth sensing moving electrode 311 is fixed to the bottom of the suspension plate, and the fourth sensing stationary electrode 312 is spaced apart on the base 201. The fourth sensing stationary electrode 312 and the fourth sensing moving electrode 311 are opposite to each other to form a capacitor structure. The capacitance value is changed by adjusting the distance between the fourth sensing stationary electrode 312 and the fourth sensing moving electrode 311.

[0111] Vibration of the diaphragm 203 activates the electrostatic clutch 100, generating electrostatic force. The clutch stator shifts under the alternating displacement of the clutch rotor, causing a change in the distance between the fourth sensing moving electrode 311 and the fourth sensing stationary electrode 312. This allows the capacitor structure to output a changing electrical signal. The working principle of the capacitor structure is common knowledge to those skilled in the art.

[0112] Reference Figure 14 As shown, this is the sixth type of MEMS capacitor microphone 200 of the present invention. The electrostatic clutch 100 includes a seventh connecting part 113, a third suspension beam 114, and a third suspension plate 115, wherein:

[0113] One end of the seventh connecting part 113 is connected to the connecting rod 205, and the other end of the seventh connecting part 113 is connected to a plurality of bias electrode arrays 102. The plurality of bias electrode arrays 102 constitute the rotor of the electrostatic clutch 100. The displacement of the diaphragm 203 will cause the bias electrode arrays 102 to shift synchronously.

[0114] The third suspension plate 115 is suspended and supported in the vacuum cavity 204 by the third suspension beam 114 on both sides. The third suspension plate 115 is provided with a receiving cavity 116 and a plurality of high-impedance node electrode arrays 101. The plurality of high-impedance node electrode arrays 101 are spaced apart on opposite sides of the receiving cavity 116. A fourth gap is formed between adjacent high-impedance node electrode arrays 101. The plurality of high-impedance node electrode arrays 101 constitute the stator of the electrostatic clutch 100.

[0115] Each of the bias electrode arrays 102 corresponds to one of the fourth gaps and extends into the fourth gap.

[0116] The capacitance sensing structure 300 includes a fifth sensing active electrode 313 and a fifth sensing static electrode 314 housed within the receiving cavity 116. Both ends of a plurality of the fifth sensing active electrodes 313 are fixed to the wall of the receiving cavity 116. The fifth sensing static electrode 314 is supported on the base 201 by a bracket. The fifth sensing static electrode 314 and the fifth sensing active electrode 313 are spatially separated and intersect each other to form a capacitor structure. The capacitance value is changed by adjusting the distance between the fifth sensing static electrode 314 and the fifth sensing active electrode 313.

[0117] Vibration of the diaphragm 203 activates the electrostatic clutch 100, generating electrostatic force. The clutch stator shifts under the alternating displacement of the clutch rotor, causing a change in the distance between the fifth sensing moving electrode 313 and the fifth sensing stationary electrode 314. This allows the capacitor structure to output a changing electrical signal. The working principle of the capacitor structure is common knowledge to those skilled in the art.

[0118] Previous embodiments have all considered a comb-shaped design for the electrostatic clutch 100, in which the bias electrode array 102 and the high-impedance node electrode array 101 slide relative to each other on the z-axis while maintaining a fixed gap. In the following embodiment, the bias electrode array 102 moves relative to the high-impedance node electrode array 101 in the xy-plane with a fixed z-axis gap, referring to... Figure 16 and Figure 17As shown, the bias electrode array 102 is connected to the diaphragm 203. The diaphragm 203 is located within the passage channel and can reciprocate within the passage channel along the arrangement direction of the bias electrodes 1021. In this embodiment, a plurality of bias electrodes 1021 within the bias electrode array 102 are arranged in the x-axis direction, and the diaphragm 203 also reciprocates in the x-axis direction. This embodiment is suitable for transforming the z-axis deformation of the diaphragm 203 into the xy plane. The lengths of the bias electrode array 102 and the high-impedance node electrode array 101 in the x-direction are not limited by the process stacking height, allowing for a large bias electrode array 102.

[0119] Reference Figure 18 As shown, this is the eighth type of MEMS capacitor microphone 200. The electrostatic clutch 100 includes an eighth connecting part 117, a fourth suspension beam 118, and a fourth suspension plate 119, wherein:

[0120] One end of the eighth connecting part 117 is connected to the connecting rod 205, and the other end of the eighth connecting part 117 is connected to a plurality of high-impedance node electrode arrays 101. The plurality of high-impedance node electrode arrays 101 constitute the rotor of the electrostatic clutch 100. The displacement of the diaphragm 203 will cause the high-impedance node electrode arrays 101 to shift synchronously.

[0121] The fourth suspension plate 118 is suspended and supported in the vacuum cavity 204 by the fourth suspension beam 119 on both sides. A plurality of bias electrode arrays 102 are spaced apart on the fourth suspension plate 118. A fifth gap and a sixth gap are formed on the fourth suspension plate 118 on opposite sides of the bias electrode arrays 102. A plurality of bias electrodes 1021 constitute the stator of the electrostatic clutch 100.

[0122] A plurality of the high-impedance node electrode arrays 101 correspond one-to-one with a plurality of the fifth gaps, and each extends into the fifth gap.

[0123] Several fifth gaps are evenly distributed on opposite sides of the sixth gap. A light reflector 315 is provided in the sixth gap. A light emitter 316 and a light detector 317 are provided on the substrate 201. The light emitter 316 may be a photodiode.

[0124] Light is emitted using a light emitter 316, which is reflected by a light reflector 316 integrated into the stator portion of the electrostatic clutch 100 and into a photodetector 317. Vibration of the diaphragm 203 activates the electrostatic clutch 100, generating an electrostatic force. This causes the light reflector 316 to deflect, altering the calculation result output by the photodetector 317. The photodetector 317 typically outputs a voltage as a function of the diaphragm displacement. This function is typically a voltage oscillating between zero and maximum voltage with a specific displacement period. The gradient of this repetitive wave, as a function of displacement, equals the sensitivity, expressed in volts per meter. For large DC displacements, the diaphragm 203 will experience positions of zero and maximum sensitivity. The use of the electrostatic clutch 100 ensures that the sensed displacement lies within the maximum sensitivity region of the optical system, independent of DC pressure.

[0125] The optical sensing system consisting of light reflector 315, light emitter 316 and light detector 317 can have higher sensitivity than capacitive sensing, which reduces the requirements for electrostatic clutch 100 and diaphragm 203, thereby allowing the use of a stiffer diaphragm 203 and / or a smaller electrostatic clutch 100 on the Z-axis, making it easier to manufacture using silicon processes.

[0126] The above description, based on the embodiments shown in the figures, details the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the figures. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, that do not exceed the spirit covered by the specification and figures, should be within the protection scope of the present invention.

Claims

1. A MEMS condenser microphone, characterized by: The loudspeaker comprises a base, a support part and a diaphragm, wherein: The diaphragm is supported above the base by the support part, and the base, the support part and the diaphragm form a vacuum cavity; The side of the diaphragm close to the vacuum cavity is connected to an electrostatic clutch through a connecting rod; The electrostatic clutch is connected to a capacitive sensing structure; The electrostatic clutch comprises: A high-impedance node electrode array, and a pass-through channel is formed between two high-impedance node electrode arrays; A bias electrode array, which can reciprocate in the pass-through channel to generate electrostatic force between the bias electrode array and the high-impedance node electrode array; The high-impedance node electrode array comprises a plurality of high-impedance node electrodes and a grounding member, an insulating silicon oxide layer is arranged between adjacent high-impedance node electrodes, and the grounding member is electrically connected to the plurality of high-impedance node electrodes and kept grounded; The high-impedance node electrode comprises a first conductive polysilicon layer, a resistance bridge layer and a second conductive polysilicon layer, the first conductive polysilicon layer is electrically connected to the second conductive polysilicon layer through the resistance bridge layer, and the grounding member is electrically connected to the plurality of second conductive polysilicon layers and kept grounded.

2. The MEMS condenser microphone according to claim 1, wherein: In each bias electrode array, two adjacent bias electrodes in the plurality of bias electrodes have opposite polarities and are connected through an insulating mechanical support.

3. The MEMS condenser microphone according to claim 2, wherein: Each bias electrode array further comprises two grounding shielding electrodes arranged at both ends of each array of the plurality of bias electrode arrays.

4. The MEMS condenser microphone of claim 1, wherein: The electrostatic clutch further comprises a first connecting part and a second connecting part, one end of the first connecting part is connected to the connecting rod, and the other end of the first connecting part is connected to the plurality of bias electrode arrays; The second connecting part is provided with two second connecting parts, the two second connecting parts are symmetrically arranged on opposite sides of the first connecting part, one end of each second connecting part is provided with a plurality of high-impedance node electrode arrays, and the other end of each second connecting part is connected to the capacitive sensing structure; The plurality of high-impedance node electrode arrays and the plurality of bias electrode arrays are arranged in a comb shape, the plurality of high-impedance node electrode arrays and the plurality of bias electrode arrays are separated in space and intersect with each other; The capacitive sensing structure comprises a first lever, a first support part, a first sensing dynamic electrode and a first sensing static electrode, a lever body of the first lever is pivoted to the first support part, one end of the first lever is connected to the second connecting part, the other end of the first lever is connected to the first sensing dynamic electrode, and the first sensing static electrode is opposite to the first sensing dynamic electrode.

5. The MEMS condenser microphone of claim 1, wherein: The electrostatic clutch further comprises a third connecting part and a fourth connecting part, one end of the third connecting part is connected to the connecting rod, and the other end of the fourth connecting part is connected to the plurality of bias electrode arrays; The fourth connecting part is provided with two, two fourth connecting parts are symmetrically arranged on the opposite sides of the third connecting part, and a plurality of high impedance node electrode arrays are connected between the two fourth connecting parts, and the other end of each fourth connecting part is connected with the capacitive sensing structure; The plurality of high impedance node electrode arrays and the plurality of bias electrode arrays are arranged in a comb shape, and the plurality of high impedance node electrode arrays and the plurality of bias electrode arrays are separated in space and intersected with each other; The capacitive sensing structure comprises a second lever, a second supporting part, a curved slit, a second sensing dynamic electrode and a second sensing static electrode, the lever body of the second lever is pivoted on the second supporting part, one end of the second lever is connected with the fourth connecting part, the other end of the second lever is connected with the second sensing dynamic electrode, the second sensing static electrode is opposite to the second sensing dynamic electrode, and the curved slit is arranged at one end of the second lever close to the fourth connecting part.

6. The MEMS condenser microphone of claim 1, wherein: The static electricity decoupler comprises a fifth connecting part, a first suspension beam and a first suspension plate, wherein: One end of the fifth connecting part is connected with the connecting rod, and the other end of the fifth connecting part is connected with a plurality of high impedance node electrode arrays; The two sides of the first suspension plate are suspended and supported in the vacuum cavity through the first suspension beam, a plurality of bias electrode arrays are arranged on the first suspension plate at intervals, and first and second gaps are respectively formed on the first suspension plate at the opposite sides of the bias electrode arrays; A plurality of high impedance node electrode arrays correspond to a plurality of first gaps respectively and extend into the first gaps; The capacitive sensing structure comprises a third sensing static electrode, a plurality of third sensing static electrodes are arranged on the substrate at intervals, a plurality of third sensing static electrodes correspond to a plurality of second gaps respectively and extend into the second gaps.

7. The MEMS condenser microphone according to claim 6, characterized in that: The third sensing static electrode comprises a first part and a second part, the first part extends into the second gap, and the second part protrudes from the second gap and extends along the length direction of the first suspension plate.

8. The MEMS condenser microphone of claim 1, wherein: The static electricity decoupler comprises a sixth connecting part, a second suspension beam and a second suspension plate, wherein: One end of the sixth connecting part is connected with the connecting rod, and the other end of the sixth connecting part is connected with a plurality of bias electrode arrays; The two sides of the second suspension plate are suspended and supported in the vacuum cavity through the second suspension beam, a plurality of high impedance node electrode arrays are arranged on the second suspension plate at intervals, and third gaps are formed between adjacent high impedance node electrode arrays; A plurality of bias electrode arrays correspond to a plurality of third gaps respectively and extend into the third gaps; The capacitive sensing structure comprises a fourth sensing dynamic electrode and a fourth sensing static electrode, the fourth sensing dynamic electrode is fixed to the bottom of the suspension plate, the fourth sensing static electrode is arranged on the substrate at intervals, and the fourth sensing static electrode is opposite to the fourth sensing dynamic electrode.

9. The MEMS condenser microphone according to claim 3, wherein: The electrostatic clutch comprises a seventh connecting part, a third suspension beam and a third suspension plate. One end of the seventh connecting part is connected with the connecting rod, and the other end of the seventh connecting part is connected with a plurality of bias electrode arrays. The two sides of the third suspension plate are suspended and supported in the vacuum cavity through the third suspension beam, and the third suspension plate is provided with a containing cavity and a plurality of high-impedance node electrode arrays. The plurality of high-impedance node electrode arrays are arranged on the opposite sides of the containing cavity, and the fourth gaps are formed between adjacent high-impedance node electrode arrays. The plurality of bias electrode arrays correspond to the plurality of fourth gaps one by one and respectively extend into the fourth gaps.

10. The MEMS condenser microphone of claim 1, wherein: The capacitive sensing structure comprises a fifth sensing dynamic electrode and a fifth sensing static electrode accommodated in the containing cavity.

11. The MEMS condenser microphone of claim 1, wherein: The two ends of the plurality of fifth sensing dynamic electrodes are fixed to the wall surface of the containing cavity, and the fifth sensing static electrode is supported on the substrate through a support. The fifth sensing static electrode and the fifth sensing dynamic electrode are spatially separated and intersected with each other. The bias electrode array is connected to the diaphragm, is located in the through channel, and can reciprocate in the through channel along the arrangement direction of the bias electrode. The electrostatic clutch comprises an eighth connecting part, a fourth suspension beam and a fourth suspension plate. One end of the eighth connecting part is connected with the connecting rod, and the other end of the eighth connecting part is connected with a plurality of high-impedance node electrode arrays. The two sides of the fourth suspension plate are suspended and supported in the vacuum cavity through the fourth suspension beam, and a plurality of bias electrode arrays are arranged on the fourth suspension plate. The opposite sides of the bias electrode array respectively form a fifth gap and a sixth gap on the fourth suspension plate. The plurality of high-impedance node electrode arrays correspond to the plurality of fifth gaps one by one and respectively extend into the fifth gaps. The plurality of fifth gaps are arranged on the opposite sides of the sixth gap, and the sixth gap is provided with a light reflector. The substrate is provided with a light emitter and a light detector.

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