MEMS structure and preparation method thereof, MEMS piezoelectric bionic vector microphone

Abstract

The present invention relates to technical fields such as the manufacture of new electroacoustic components and microelectronic devices, and in particular to a MEMS structure and a preparation method thereof, a MEMS piezoelectric bionic vector microphone. The MEMS structure of the present invention includes: a substrate, including: a substrate outer ring body, a substrate back cavity; a vibration layer, including: a fixed area; a detection area, separated from the fixed area by a slit; two rotating connection structures, respectively connected to the detection area at the front and rear sides of the fixed area, and a rotation axis is formed by the straight lines of the two rotating connection structures, and the rotation axis divides the detection area into a first rotating beam and a second rotating beam; 2N cantilever beam units, wherein the first and second rotating beams are respectively connected to the fixed area through N cantilever beam units; for each cantilever beam unit, its free end is connected to the corresponding detection area through a hinge structure; a piezoelectric functional module. The present invention can drive the cantilever beam to produce a greater bending deformation and increase the output voltage signal.

Description

Technical Field

[0001] The present invention relates to the technical fields of novel electroacoustic element manufacturing and microelectronic devices, and in particular to a MEMS structure and a preparation method thereof, and a MEMS piezoelectric bionic vector microphone. Background Art

[0002] In recent years, with the development of miniaturized devices such as drones, robots, and hearing aids, new demands have been made on sound source localization arrays, which need to work reliably and accurately when the device space size is limited. Generally speaking, the larger the aperture of the microphone array, the higher the accuracy of sound source localization and the farther the distance. However, under the condition of limited space size, traditional sound source localization methods have problems such as poor angular resolution or even failure due to limited sampling frequency and low sensitivity of received signal delay to the azimuth of the sound source. Summary of the invention

[0003] 1. Technical issues to be solved

[0004] The present invention is expected to at least partially solve one of the above technical problems.

[0005] 2. Technical Solution

[0006] A first aspect of the present invention provides a MEMS structure, comprising: a substrate, comprising: a substrate outer ring body; a substrate back cavity, formed on the inner side of the substrate outer ring body; a vibration layer, formed above the substrate outer ring body and the substrate back cavity, comprising: a fixed area, formed above the substrate outer ring body; a detection area, formed above the back cavity, separated from the fixed area by a slit; two rotating connection structures, respectively connected to the detection area at the front and rear sides of the fixed area, and a rotation axis is formed by the straight lines of the two rotating connection structures, and the rotation axis divides the detection area into a first rotating beam and a second rotating beam; 2N cantilever beam units, wherein the first rotating beam and the second rotating beam are respectively connected to the fixed area through N cantilever beam units; for each cantilever beam unit, its two sides are separated from the fixed area and the detection area by a slit, its fixed end is fixedly supported in the fixed area, and its free end is connected to the corresponding detection area through a hinge structure, N≥1; a piezoelectric functional module, comprising: 2N piezoelectric functional units, respectively arranged on the corresponding cantilever beam units.

[0007] The second aspect of the present invention provides a preparation method for preparing the above MEMS structure, including: step A, depositing a sacrificial layer and a vibration layer on a substrate in sequence; step B, depositing each layer of thin film material of a piezoelectric functional unit on the vibration layer in sequence; step C, patterning each layer of thin film material of the piezoelectric functional unit to form 2N piezoelectric functional units; step D, etching the vibration layer and the sacrificial layer to form a slit; step E, thinning the back side of the substrate to a preset thickness; step F, performing deep silicon etching on the back side of the substrate until the sacrificial layer to form a back cavity; step G, releasing the sacrificial layer, and the slit passes through the vibration layer to form a detection area, two rotating connection structures, and 2N cantilever beam units.

[0008] A third aspect of the present invention provides a MEMS piezoelectric bionic vector microphone, comprising: the above MEMS structure; wherein the signal output by each piezoelectric functional unit ultimately obtains a sound source localization signal.

[0009] 3. Beneficial Effects

[0010] It can be seen from the above technical solution that the present invention has at least one of the following beneficial effects compared with the prior art:

[0011] 1. In the prior art CN117560611B, the free ends of the cantilever beam units are directly connected to the detectors. However, in the application of MEMS bionic vector microphones, weak signals are easily masked by noise.

[0012] Compared with the prior art, the present invention connects the free end of the cantilever beam unit and the detection area through a hinge structure, which can reduce the local bending stiffness at the connection between the cantilever beam and the detection area and increase the rotational displacement of the detection area, thereby driving the cantilever beam to produce greater bending deformation and increasing the output voltage signal.

[0013] 2. In the first hinge structure, at the free end of the cantilever beam unit, the slits on both sides extend toward the inner side of the cantilever beam unit to form a first extended slit, so that the width of the free end of the cantilever beam unit becomes narrower to form a connecting detail; a semi-closed slit is formed on the side of the detection area close to the free end or the side of the fixed end of the cantilever beam unit, and the semi-closed slit is arranged opposite to the connecting detail, and its extended line is parallel to the first extended slit; wherein the first extended slit, the connecting detail, and the semi-closed slit form the hinge structure.

[0014] This hinge structure connects the detection area and the cantilever beam through two connecting bends symmetrically along the central axis of the cantilever beam unit, and has stronger stability and reliability than a single connecting bend.

[0015] 3. In the second hinge structure, at the free end of the cantilever beam unit, the slits on both sides extend toward the inner side of the cantilever beam unit but are staggered to form a second extended slit, forming a connecting bend portion between the free end of the cantilever beam unit and the detection area; wherein, the second extended slit and the connecting bend portion form the hinge structure.

[0016] This hinge structure connects the detection area and the cantilever beam through a connecting bending part. Compared with multiple connecting bending parts, it has lower bending stiffness and tensile stiffness, can better increase the rotational displacement of the detection area and the bending deformation of the cantilever beam, and increase the output voltage signal.

[0017] 4. In the prior art CN117560611B, one side of the rotating connection structure is connected to the detection area, and the other side is connected to the fixed area of ​​the vibration layer above the substrate. The thickness of the rotating connection structure is relatively thin. During operation, the rotating connection structure does not produce a good rotation, but a relatively serious torsion occurs, generating a large torque, and in severe cases, it will be twisted off. In addition, the fracture strength of the connection structure is low. When the device is subjected to an impact load, it may break, and the stability and reliability are relatively poor.

[0018] The rotating connection structure in the present invention is completely connected to the substrate support column at the bottom, which enhances the fracture strength. In addition, its periphery is separated from the other parts of the support column by a slit, that is, the long strip rotating connection structure is composed of a long strip support layer and a long strip substrate, and its projections completely overlap. The bottom of the long strip substrate part is connected to the substrate support column, and the left and right sides of the rotating connection structure and the side close to the edge substrate are completely free. During operation, the rotating connection structure slightly bends to the left and right sides to control the detection structure to produce a better rotation, and no torque is generated in the connection structure. In general, the stability and reliability are relatively high.

[0019] 5. Experiments have shown that the MEMS structure of the present invention achieves a sensitivity of more than -82dB in the range of 20Hz to 10kHz, and has good directivity in the horizontal direction (sensitive axis direction), and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a three-dimensional diagram of the first embodiment of the MEMS structure of the present invention.

[0021] Figure 2 to Figure 5 They are Figure 1 The MEMS structure shown includes a top view, a bottom perspective view, a cross-sectional view along AA, and a cross-sectional view along BB.

[0022] Figure 6A to Figure 6G for Figure 1 The MEMS structure is shown as a cross-sectional view after various steps in the fabrication process.

[0023] Fig. 7A , Figure 7B for Figure 1 First-order and second-order eigenmode plots of the MEMS structure shown.

[0024] Figure 8 for Figure 1 Frequency response curve of the MEMS structure shown.

[0025] Fig. 9 for Figure 1 Directivity diagram of the MEMS structure shown.

[0026] Figures 10A to 10F FIG. 4 is a top view of a MEMS structure according to another embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention proposes a MEME structure and a MEMS piezoelectric bionic vector microphone based on the Omya palm fly, and designs a rotating beam structure similar to a "seesaw". The structure has a first rotation mode excited by a pressure gradient, can amplify tiny pressure gradient signals, and has a directional response to sound pressure signals. The precise positioning of the sound source can be achieved through a single millimeter-level MEMS chip, meeting the development needs of modern miniaturized equipment.

[0028] The technical principle on which the present invention is based is first described below.

[0029] In miniaturized devices, it is highly desirable for directional microphones to be on the order of a few millimeters in size for better integration with the device. Although directional microphones have been used in audio applications for decades, their design is very challenging when applied to miniaturized devices. Since directional microphones need to detect the sound pressure difference at at least two points during operation, as the spacing and size of the microphones decrease, the difference in the measured pressure also decreases proportionally, resulting in a very low output electrical signal that is difficult to detect. When the size of the microphone is much smaller than the wavelength of the sound wave, the pressure reaching the microphone surface along the sensitive axis can be approximately expressed by a two-term Taylor series related to the coordinates of the sensitive axis.

[0030] P(x,t)=P0e jωt -jkxP0e jωt

[0031] Where P0 represents the amplitude of the incident pressure, t, ω, and k represent time, angular frequency, and wave number, respectively, and x represents the distance of a point on the microphone's sensitive axis from the starting point. The pressure gradient in the propagation direction comes from the weak contribution of the second term in the above expression, which is difficult to detect with a conventional pressure difference microphone.

[0032] The ears of the Omea palm fly can detect sound pressure gradients of this magnitude because there is a mechanical connection between its eardrums, causing the two ears to move in opposite directions in response to pressure differences on their outer surfaces. This way of detecting pressure gradients can accurately locate the location of the sound source. The applicant realized that the small bionic microphone based on the Omea palm fly is an important means to break through the basic size limitation of sound source localization. Compared with traditional microphone sound source localization arrays, bionic microphones have the advantages of small size, low power consumption and easy portability.

[0033] Based on the above principle, the present invention proposes a MEMS structure with a “seesaw” structure and a MEMS piezoelectric vector microphone.

[0034] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific implementation methods and with reference to the accompanying drawings.

[0035] The present invention first provides a MEMS structure and a method for preparing the same, and provides a MEMS piezoelectric bionic vector microphone based on the MEMS structure. The following mainly describes the application scenarios of the MEMS piezoelectric bionic vector microphone, but the present invention is not limited thereto. In other embodiments of the present invention, the MEMS structure can also be applied to other fields, such as microphones, speakers, pressure sensors or other actuators, which are also within the protection scope of the present invention.

[0036] 1. First Embodiment of MEMS Structure and Preparation Method thereof, MEMS Piezoelectric Bionic Vector Microphone

[0037] Figure 1 It is a three-dimensional diagram of the first embodiment of the MEMS structure of the present invention. Figure 2 to Figure 5 They are Figure 1 The top view, bottom perspective view, cross-sectional view along AA, and cross-sectional view along BB of the MEMS structure shown. Figure 1 to Figure 5 , the MEMS structure of this embodiment includes:

[0038] The substrate 10 comprises: a substrate outer ring body 11; a substrate back cavity 12 formed on the inner side of the substrate outer ring body;

[0039] The vibration layer 30 is formed on the outer ring of the substrate and the substrate back cavity, and includes:

[0040] A fixed area is formed above the outer ring of the substrate;

[0041] a detection area, formed above the back cavity and separated from the fixing area by a slit 50;

[0042] Two rotating connection structures are connected to the detection area at the front and rear sides of the fixed area respectively, and a rotation axis 33 is formed through the straight line of the two rotating connection structures, and the rotation axis 33 divides the detection area into a first rotating beam 32 and a second rotating beam 34;

[0043] 2N cantilever beam units, wherein the first rotating beam and the second rotating beam are connected to the fixed area through N cantilever beam units respectively; for each cantilever beam unit, two sides thereof are separated from the fixed area and the detection area by slits, the fixed end thereof is fixedly supported in the fixed area, and the free end thereof is connected to the corresponding detection area through a hinge structure, N≥1;

[0044] The piezoelectric functional module includes: 2N piezoelectric functional units 40, which are respectively arranged on corresponding cantilever beam units.

[0045] The various components of the MEMS structure of this embodiment are described in detail below.

[0046] In this embodiment, the material of the substrate is: silicon or silicon-based compound; the material of the vibration layer is one or more of the following materials: silicon, silicon nitride, silicon oxide, piezoelectric material. Those skilled in the art should understand that the above is only a preferred implementation of the present invention. In actual applications, those skilled in the art can also select the materials of the substrate and the vibration layer according to the actual scene requirements.

[0047] Figure 1 In the present invention, a sacrificial layer 20 is provided between the substrate 10 and the vibration layer 30. The sacrificial layer 20 is used for back cavity etching of the substrate 10. Since the sacrificial layer 20 has no additional functions, it is described as a part of the substrate 10 in the following. Moreover, after the technical process is advanced, the back cavity etching may be performed without the sacrificial layer, which is also within the protection scope of the present invention.

[0048] Please refer to Figure 3 The substrate back cavity 12 is in the shape of a rectangular parallelepiped as a whole; at the midpoint of the two long sides of the substrate back cavity, the substrate outer ring body and the fixed area extend toward the inner side of the substrate back cavity to form two symmetrical support columns 13. The rotating connection structure is in the shape of a long strip, the lower part of which is connected to the support column, and the periphery of which is separated from the other parts of the support column by a slit; the detection area between the two rotating connection structures constitutes a rotating beam of the detection area.

[0049] In the prior art CN117560611B, one side of the rotating connection structure is connected to the detection area, and the other side is connected to the fixed area of ​​the vibration layer above the substrate. The thickness of the rotating connection structure is relatively thin. During operation, the rotating connection structure does not produce a good rotation, but will produce a relatively serious torsion, generate a large torque, and even break in severe cases. In addition, the fracture strength of the connection structure is low. When the device is subjected to an impact load, it may break, and the stability and reliability are relatively poor.

[0050] The rotating connection structure in this embodiment is completely connected to the substrate support column at the bottom, which enhances the fracture strength. In addition, its periphery is separated from the other parts of the support column by a slit, that is to say, the long strip rotating connection structure is composed of a long strip support layer and a long strip substrate, and its projections completely overlap. The bottom of the long strip substrate part is connected to the substrate support column, and the left and right sides of the rotating connection structure and the side close to the edge of the substrate are completely free. During operation, the rotating connection structure slightly bends to the left and right sides to control the detection structure to produce a better rotation, and no torque is generated in the connection structure. In general, the stability and reliability are relatively high.

[0051] Those skilled in the art should understand that the rotary connection structure in the prior art CN117560611B can also be applied to the present invention, but its stability and reliability are worse than those of the rotary connection structure of this embodiment.

[0052] Specifically, in this embodiment, the horizontal cross-section of the rotating connection structure is rectangular; the length of the rotating connection structure is between 50 μm and 500 μm, and the width is between 10 μm and 100 μm. Those skilled in the art should understand that in practical applications, the shape and size of the rotating connection structure can also be specifically designed according to the needs of the actual scene, which is also within the scope of protection of the present invention.

[0053] Specifically, in this embodiment, the substrate back cavity 12 is in the shape of a rectangular parallelepiped as a whole; the length and width range is 0.1mm-10mm, and the aspect ratio is greater than or equal to 4 / 3. Those skilled in the art should understand that the above is only a preferred implementation of the present invention. In practical applications, the shape and size of the substrate back cavity can also be specifically designed according to the needs of the actual scene. For example, the horizontal cross-section of the substrate back cavity is set to a circular or elliptical shape. These deformation methods can also implement the present invention and are also within the scope of protection of the present invention.

[0054] In this embodiment, the piezoelectric functional unit refers to a device that generates an electrical signal due to the deformation of the piezoelectric material, which can be expressed in various implementation forms. In the first implementation form, the piezoelectric functional unit includes: a lower electrode layer, a piezoelectric layer, and an upper electrode layer arranged in sequence from bottom to top. In the second implementation form, the piezoelectric functional unit includes: a lower electrode layer, a lower piezoelectric layer, a middle electrode layer, an upper piezoelectric layer, and an upper electrode layer arranged in sequence from bottom to top.

[0055] Among them, the materials of the piezoelectric layer, the lower piezoelectric layer, and the upper piezoelectric layer are one or more of the following materials: aluminum nitride, scandium-doped aluminum nitride, zinc oxide, and piezoelectric ceramics, and their thickness range is: 0.1μm-10μm; the materials of the lower electrode layer, the upper electrode layer, and the middle electrode layer are one or more of the following materials: molybdenum, gold, aluminum, and chromium, and their thickness range is: 20nm-200nm.

[0056] Those skilled in the art should understand that the specific structure and material selection of the piezoelectric functional unit are not the focus of the present invention and will not be described similarly here.

[0057] Please continue to refer to Figure 1 to Figure 5 In this embodiment, a slit with a specific pattern runs through the entire vibration layer, dividing the vibration layer into a detection area and a fixed area. The width of the slit is between 5 μm and 50 μm.

[0058] Furthermore, the rotating axis divides the detection area into a first rotating beam 32 and a second rotating beam 34. The main parts of the first rotating beam 32 and the second rotating beam 34 are symmetrical with respect to the rotating axis. The detection area is composed of two rotating beams and a rotating axis to form a "seesaw" structure. The fixed area includes 8 cantilever beam units. One end of each cantilever beam unit is fixed on the fixed area, and the other end is hinged to the rotating beam through a hinge structure. The piezoelectric functional unit is graphically divided into 8 parts, corresponding to the 8 beam units respectively. One end of the piezoelectric functional unit is flush with the substrate or covers a part of the substrate, and the main part is located on the cantilever beam unit. The width of the piezoelectric functional unit is less than or equal to the cantilever beam unit, and the length is determined according to the maximum output energy.

[0059] In this embodiment, the first rotating beam 32 and the second rotating beam 34 are used to detect the sound pressure gradient. The two rotating beams are connected to the rotating shaft 33. The rotating shaft 33 has extremely low rotational stiffness. The sound pressure gradient forms a torque on the left and right sides of the rotating beam, pushing it to rotate around the rotating shaft 33, causing the first rotating beam 32 and the second rotating beam 34 to produce reverse displacement, and then drive the cantilever beam units 31 on both sides to produce opposite displacement through the hinge 51, output anti-phase electrical signals, and differentiate the anti-phase electrical signals to complete the amplification of the sound pressure gradient signal. The symmetrical arrangement of the eight cantilever beam units 31 helps to improve the reliability of the structure, and the hinge structure 51 helps to reduce local bending stiffness and increase displacement.

[0060] In the prior art CN117560611B, the free ends of the cantilever beam units are directly connected to the detectors, but in the application of MEMS bionic vector microphones, weak signals are easily masked by noise. Compared with the prior art, the present invention connects the free ends of the cantilever beam units and the detection area through a hinge structure, which can reduce the local bending stiffness at the connection between the cantilever beam and the detection area, increase the rotational displacement of the detection area, thereby driving the cantilever beam to produce greater bending deformation and increase the output voltage signal. The present invention provides different forms of hinge structures, which are described below.

[0061] (I) The first hinge structure

[0062] Please refer to Figure 1 to Figure 5 As shown, both sides of the cantilever beam unit 31 are slits; at the free end of the cantilever beam unit, the slits on both sides extend toward the inner side of the cantilever beam unit to form a first extended slit, so that the width of the free end of the cantilever beam unit becomes narrower to form a connecting detail; on the side of the detection area close to the free end or the side of the fixed end of the cantilever beam unit, a semi-closed slit is formed, and the semi-closed slit is arranged opposite to the connecting detail, and its extension line is parallel to the first extended slit; wherein the first extended slit, the connecting detail, and the semi-closed slit form the hinge structure.

[0063] Preferably, the semi-sealed slit is formed on one side of the detection area close to the free end; at the free end of the cantilever beam unit, the slits on both sides extend symmetrically toward the inner side of the cantilever beam unit; wherein the length of each first extended slit is greater than or equal to 1 / 50 of the width of the cantilever beam unit, and the length of the sealed slit is greater than the width of the connecting detail of the cantilever beam unit and less than or equal to 24 / 25 of the width of the cantilever beam unit. The interval between the first extended slit and the sealed slit is less than or equal to 150 μm and greater than or equal to 5 μm.

[0064] This hinge structure connects the detection area and the cantilever beam through two connecting bends symmetrically along the central axis of the cantilever beam unit, and has stronger stability and reliability than a single connecting bend.

[0065] Those skilled in the art should understand that the above are only preferred embodiments of the present invention. In other embodiments of the present invention, the extension length of the slit, the length of the sealing slit, the interval between the extension slit and the sealing slit, etc. can be adjusted as needed, all within the protection scope of the present invention.

[0066] 2. The second hinge structure

[0067] For this kind of hinge structure, both sides of the cantilever beam unit are slits; at the free end of the cantilever beam unit, the slits on both sides extend toward the inner side of the cantilever beam unit but are staggered to form a second extended slit, forming a connecting curved portion between the free end of the cantilever beam unit and the detection area; wherein, the second extended slit and the connecting curved portion form the hinge structure.

[0068] Preferably, the length of each second extended slit is greater than 1 / 2 of the width of the cantilever beam unit; and the interval between two second extended slits is less than or equal to 150 μm and greater than or equal to 5 μm.

[0069] This hinge structure connects the detection area and the cantilever beam through a connecting bending part. Compared with multiple connecting bending parts, it has lower bending stiffness and tensile stiffness, can better increase the rotational displacement of the detection area and the bending deformation of the cantilever beam, and increase the output voltage signal.

[0070] Those skilled in the art should understand that the above are only preferred embodiments of the present invention. In other embodiments of the present invention, the extension length of the second extension slit, the interval between the two second extension slits, etc. can be adjusted as needed, all within the protection scope of the present invention.

[0071] The following is a detailed description of the rotating beam and cantilever beam in the MEMS structure of this embodiment. Figure 1 to Figure 5 , "a-h" represent corresponding piezoelectric functional units, and the cantilever beam where each piezoelectric functional unit is located is called the "first cantilever beam". In this embodiment,

[0072] The first rotating beam 32 is connected to the fixed area through the a, b, c, d cantilever beams, wherein:

[0073] The a-th cantilever beam and the b-th cantilever beam are arranged on a side of the first rotating beam away from the rotating axis, and the two extend in a direction parallel to the rotating axis, and are arranged opposite to each other and separated by a preset distance;

[0074] The c-th cantilever beam and the d-th cantilever beam are arranged on one side of the first rotating beam close to the rotating axis, and the fixed ends of the two cantilever beams are respectively connected to the fixed layers above the two supporting columns, and the two cantilever beams are respectively arranged on the front and rear sides of the first rotating beam, and the two cantilever beams extend in a direction perpendicular to the rotating axis;

[0075] The second rotating beam 34 is connected to the fixed area through the e, f, g, h cantilever beams, wherein:

[0076] The g-th cantilever beam is symmetrical with the a-th cantilever beam relative to the rotation axis; the h-th cantilever beam is symmetrical with the b-th cantilever beam relative to the rotation axis;

[0077] The e-th cantilever beam and the c-th cantilever beam are symmetrical with respect to the rotation axis; the f-th cantilever beam and the d-th cantilever beam are symmetrical with respect to the rotation axis.

[0078] The piezoelectric functional module includes: piezoelectric functional units a, b, c, d, e, f, g, and h, which are respectively arranged on corresponding cantilever beam units.

[0079] It can be seen that in the cantilever beam setting of this embodiment, the four cantilever beams of the first rotating beam 32 and the four cantilever beams of the second rotating beam 34 are: symmetrical with respect to the rotation axis; symmetrical with respect to the center point of the detection area; and symmetrical with respect to the transverse symmetry axis passing through the center point of the detection area and perpendicular to the rotation axis.

[0080] The following is a method for preparing the MEMS structure of this embodiment. Figure 4 The cross-sectional view along the middle BB is used as an example to introduce the process flow of the MEMS structure. Figure 6A-6G The preparation method of this embodiment includes:

[0081] Step A, depositing a sacrificial layer and a vibration layer in sequence on a silicon substrate by low pressure chemical vapor deposition, such as Fig. 6A shown.

[0082] Step B, depositing a bottom electrode, a piezoelectric layer and a top electrode in sequence on the front vibration layer by magnetron sputtering, such as Figure 6B shown.

[0083] Step C, etching the top electrode, piezoelectric layer and bottom electrode in sequence from top to bottom to form 8 piezoelectric functional units, such as Figure 6C shown.

[0084] Step D, etching the vibration layer and the sacrificial layer to form a slit, such as Fig.6D shown.

[0085] Step E, thinning the substrate on the back side to a preset thickness, such as Fig. 6E shown.

[0086] Step F, deep silicon etching to the sacrificial layer to form a back cavity, such as Fig. 6F shown.

[0087] Step G, releasing the sacrificial layer, and the slits penetrate the vibration layer to form the detection area, two rotating connection structures, and 2N cantilever beam units to obtain the final MEMS structure, such as Figure 6G shown.

[0088] The following introduces the MEMS piezoelectric bionic vector microphone based on the MEMS structure of this embodiment. For the MEMS piezoelectric bionic vector microphone using the MEMS structure of this embodiment, eight piezoelectric functional units correspond to eight electrical signal output ports a to h, which are preferably divided into four pairs of ab, cd, ef, and gh, where two ports in each pair are connected in parallel to form new electrical signal output ports 1 to 4 in sequence, 1 and 2 are connected in series to output electrical signal 5, 3 and 4 are connected in series to output electrical signal 6, and finally electrical signals 5 and 6 are differentiated to obtain an accurate sound source direction signal. Specifically:

[0089] ① The signals output by the a and b piezoelectric functional units are connected in parallel and used as the first electrical signal;

[0090] ② The signals output by the cth and dth piezoelectric functional units are connected in parallel and used as the second electrical signal;

[0091] ③ The signals output by the e-th and f-th piezoelectric functional units are connected in parallel and used as the third electrical signal;

[0092] ④ The signals output by the g and h piezoelectric functional units are connected in parallel and used as the fourth electrical signal;

[0093] ⑤ After the first and second electrical signals are connected in series, the fifth electrical signal is output;

[0094] ⑥ The 3rd and 4th electrical signals are connected in series to output the 6th electrical signal;

[0095] ⑦ The sound source localization signal is obtained by differentiating the 5th and 6th electrical signals.

[0096] Fig. 7A and Figure 7B are the first two eigenmodes of the MEMS structure in this embodiment. The omnidirectional component of the sound pressure signal drives the two ends of the beam to vibrate in phase (i.e., bending mode), while the gradient load generates a net torque on the beam, driving the two ends of the beam to move out of phase (i.e., rotational mode). The contribution of the first vibration mode to the microphone frequency response should be suppressed as much as possible to achieve a pure gradient microphone.

[0097] Figure 8 The sensitivity frequency response under a certain structural size parameter achieves a sensitivity of more than -82dB in the range of 20Hz to 10kHz.

[0098] Fig. 9 2 is the normalized directivity diagram corresponding to 1 kHz. It can be seen that the MEMS piezoelectric vector microphone structure in the present invention has good directivity in the horizontal direction (sensitive axis direction).

[0099] In summary, experiments have shown that the MEMS structure of this embodiment achieves a sensitivity of more than -82dB in the range of 20Hz to 10kHz, and has good directivity in the horizontal direction (sensitive axis direction), and has good application prospects.

[0100] 2. MEMS Structure Second Embodiment: MEMS Piezoelectric Bionic Vector Microphone

[0101] Fig. 10A FIG. 2 is a top view of the second embodiment of the MEMS structure of the present invention. Fig. 10A As shown, the difference between this embodiment and the first embodiment of the MEMS structure lies in: the number of cantilever beams, the symmetry relationship, and the setting position. Specifically, this embodiment sets four cantilever beams, and the cantilever beams of the two rotating beams are symmetric with respect to the rotation axis.

[0102] Specifically, the first rotating beam is connected to the fixed area through the a-th cantilever beam and the b-th cantilever beam; the a-th cantilever beam and the b-th cantilever beam are arranged on the side of the first rotating beam away from the rotation axis, and the two extend in a direction parallel to the rotation axis, and the two are arranged opposite to each other and separated by a preset distance. The second rotating beam is connected to the fixed area through the g-th cantilever beam and the h-th cantilever beam, and the g-th cantilever beam is symmetrical with the a-th cantilever beam relative to the rotation axis; the h-th cantilever beam is symmetrical with the b-th cantilever beam relative to the rotation axis. The piezoelectric functional module includes: the a-th, b-th, g-th, and h-th piezoelectric functional units, which are respectively arranged on the corresponding cantilever beam units.

[0103] Regarding other parts and preparation methods of the MEMS structure of this embodiment, reference may be made to the relevant description of the first embodiment of the MEMS structure, which will not be repeated here.

[0104] Based on the above-mentioned second embodiment of the MEMS structure, the present invention further provides a MEMS piezoelectric bionic vector microphone. The MEMS piezoelectric bionic vector microphone of this embodiment includes: Fig. 10A The MEMS structure shown in FIG. Among them, the signals output by the a and b piezoelectric functional units are connected in parallel as the first electrical signal; the signals output by the g and h piezoelectric functional units are connected in parallel as the fourth electrical signal, and the first and fourth electrical signals are differentiated to obtain a sound source localization signal.

[0105] 3. MEMS Structure Third Embodiment: MEMS Piezoelectric Bionic Vector Microphone

[0106] Fig. 10B FIG. 1 is a top view of the third embodiment of the MEMS structure of the present invention. Fig. 10B As shown, the difference between this embodiment and the first embodiment of the MEMS structure lies in: the number of cantilever beams, the symmetry relationship, and the setting position. Specifically, this embodiment sets two cantilever beams, and the cantilever beams of the two rotating beams are symmetrical with respect to the center point of the detection area.

[0107] like Fig. 10B As shown, the first rotating beam is connected to the upper fixed area through the ath cantilever beam, or is connected to the lower fixed area through the upper and lower mirror images; the ath cantilever beam is arranged on the side of the first rotating beam away from the rotation axis, and extends in the direction parallel to the rotation axis; the second rotating beam is connected to the lower fixed area through the hth cantilever beam, or is connected to the upper fixed area through the upper and lower mirror images, and the hth cantilever beam and the ath cantilever beam are centrally symmetrical with respect to the center point of the detection area; the piezoelectric functional module includes: the ath and hth piezoelectric functional units, which are respectively arranged on the corresponding cantilever beam units.

[0108] Regarding other parts and preparation methods of the MEMS structure of this embodiment, reference may be made to the relevant description of the first embodiment of the MEMS structure, which will not be repeated here.

[0109] Based on the third embodiment of the MEMS structure, the present invention further provides a MEMS piezoelectric bionic vector microphone. The MEMS piezoelectric bionic vector microphone of this embodiment includes: Fig. 10B The MEMS structure shown in FIG. 1 is a MEMS structure in which the signal output by the ath piezoelectric functional unit is used as the first electrical signal; the signal output by the hth piezoelectric functional unit is used as the fourth electrical signal, and the first and fourth electrical signals are differentiated to obtain a sound source localization signal.

[0110] 4. MEMS Structure Fourth Embodiment: MEMS Piezoelectric Bionic Vector Microphone

[0111] Fig. 10C FIG. 4 is a top view of the fourth embodiment of the MEMS structure of the present invention. Fig. 10C As shown, the difference between this embodiment and the first embodiment of the MEMS structure lies in: the number of cantilever beams, the symmetry relationship, and the setting position. Specifically, this embodiment sets four cantilever beams, and the cantilever beams of the two rotating beams are symmetrical with respect to the rotation axis.

[0112] Please refer to Fig. 10C The first rotating beam is connected to the fixed area through the cth cantilever beam and the dth cantilever beam. The cth cantilever beam and the dth cantilever beam are arranged on the side of the first rotating beam close to the rotating axis. The fixed support sections of the two are respectively connected to the fixed layer above the two supporting columns. The two are respectively arranged on the front and rear sides of the first rotating beam, and the two extend in the direction perpendicular to the rotating axis.

[0113] Please refer to Fig. 10C The second rotating beam is connected to the fixed area through the e-th cantilever beam and the f-th cantilever beam. The e-th cantilever beam and the c-th cantilever beam are symmetrical with respect to the rotation axis; the f-th cantilever beam and the d-th cantilever beam are symmetrical with respect to the rotation axis.

[0114] The piezoelectric functional module includes: c, d, e, and f piezoelectric functional units, which are respectively arranged on corresponding cantilever beam units.

[0115] Regarding other parts and preparation methods of the MEMS structure of this embodiment, reference may be made to the relevant description of the first embodiment of the MEMS structure, which will not be repeated here.

[0116] Based on the fourth embodiment of the MEMS structure, the present invention further provides a MEMS piezoelectric bionic vector microphone. The MEMS piezoelectric bionic vector microphone of this embodiment includes: Fig. 10C The MEMS structure shown in FIG. Among them, the signals output by the cth and dth piezoelectric functional units are connected in parallel as the second electrical signal; the signals output by the eth and fth piezoelectric functional units are connected in parallel as the third electrical signal, and the difference between the second and third electrical signals is used to obtain the sound source localization signal.

[0117] V. MEMS Structure Fifth Embodiment: MEMS Piezoelectric Bionic Vector Microphone

[0118] Fig. 10D FIG. 5 is a top view of the fifth embodiment of the MEMS structure of the present invention. Fig. 10D As shown, the difference between this embodiment and the first embodiment of the MEMS structure is: the number of cantilever beams, the symmetry relationship, and the setting position. Specifically, this embodiment sets two cantilever beams - the cth cantilever beam and the fth cantilever beam, and the cantilever beams of the two rotating beams are symmetrical with respect to the center point of the detection area.

[0119] Please refer to Fig. 10D The c-th cantilever beam is arranged on one side of the first rotating beam close to the rotating axis and extends in a direction perpendicular to the rotating axis; the first rotating beam is connected to the fixed layer on the upper supporting column through the c-th cantilever beam, or is connected to the fixed layer on the lower supporting column in an upper and lower mirror image.

[0120] Please refer to Fig. 10D , the second rotating beam is connected to the fixed layer on the lower support column through the fth cantilever beam, or is connected to the fixed layer on the upper support column in an upper and lower mirror image, and the fth cantilever beam and the cth cantilever beam are centrally symmetrical with respect to the center point of the detection area;

[0121] Wherein, the piezoelectric functional module includes: the cth and fth piezoelectric functional units, which are respectively arranged on the corresponding cantilever beam units.

[0122] Regarding other parts and preparation methods of the MEMS structure of this embodiment, reference may be made to the relevant description of the first embodiment of the MEMS structure, which will not be repeated here.

[0123] Based on the fifth embodiment of the MEMS structure, the present invention further provides a MEMS piezoelectric bionic vector microphone. The MEMS piezoelectric bionic vector microphone of this embodiment includes: Fig. 10DThe MEMS structure shown in FIG. 1 is a MEMS structure in which the signal output by the cth piezoelectric functional unit is used as the second electrical signal; the signal output by the fth piezoelectric functional unit is used as the third electrical signal, and the second and third electrical signals are differentiated to obtain a sound source localization signal.

[0124] VI. MEMS Structure Sixth Embodiment: MEMS Piezoelectric Bionic Vector Microphone

[0125] Fig.10E FIG. 6 is a top view of the sixth embodiment of the MEMS structure of the present invention. Fig.10E As shown, the difference between this embodiment and the first embodiment of the MEMS structure lies in: the number of cantilever beams, symmetry relationship, and setting position. Specifically, this embodiment sets two L-shaped cantilever beams, and the cantilever beams of the two rotating beams are symmetrical with respect to the center point of the detection area.

[0126] like Fig.10E As shown, the first rotating beam is connected to the fixed area through the i-th cantilever beam, the i-th cantilever beam is in an L shape or an L shape after the upper and lower mirror transformation, its fixed support end is connected to the fixed layer above one of the support columns, its straight section extends in the direction perpendicular to the rotating axis, its bent section extends along the edge of the first rotating beam away from the rotating axis, and its free end is connected to the first rotating beam;

[0127] like Fig.10E As shown, the second rotating beam is connected to the fixed area through the jth cantilever beam, and the jth cantilever beam is centrally symmetrical with the ith cantilever beam about the center point of the detection area;

[0128] Wherein, the piezoelectric functional module includes: i-th and j-th piezoelectric functional units, which are respectively arranged on corresponding cantilever beam units.

[0129] Regarding other parts and preparation methods of the MEMS structure of this embodiment, reference may be made to the relevant description of the first embodiment of the MEMS structure, which will not be repeated here.

[0130] Based on the sixth embodiment of the above-mentioned MEMS structure, the present invention further provides a MEMS piezoelectric bionic vector microphone. The MEMS piezoelectric bionic vector microphone of this embodiment includes: Fig.10E The MEMS structure shown in the figure; wherein, the sound source localization signal is obtained by differentiating the signals output by the i-th and j-th piezoelectric functional units.

[0131] VII. MEMS Structure Seventh Embodiment: MEMS Piezoelectric Bionic Vector Microphone

[0132] Fig.10F FIG. 1 is a top view of the seventh embodiment of the MEMS structure of the present invention. Fig.10FAs shown, the difference between this embodiment and the first embodiment of the MEMS structure is: the number of cantilever beams, the symmetry relationship, and the setting position. Specifically, this embodiment sets four L-shaped cantilever beams - the kth, lth, mth, and nth cantilever beams, and the cantilever beams of the two rotating beams are symmetrical relative to the center point of the detection area.

[0133] like Fig.10F As shown, the first rotating beam is connected to the fixed area through the kth cantilever beam and the lth cantilever beam, the kth cantilever beam and the lth cantilever beam are both L-shaped, and the fixed ends of the two are respectively connected to the fixed layers above the two support columns; the free ends of the two are opposite and separated by a preset distance; the straight segments and the bent segments of the two are arranged along the edge of the first rotating beam; the two are symmetrical with respect to the transverse symmetry axis passing through the center point of the detection area and perpendicular to the rotation axis.

[0134] like Fig.10F As shown, the second rotating beam and the first rotating beam are symmetrical with respect to the rotation axis; the second rotating beam is connected to the fixed area through the mth cantilever beam and the nth cantilever beam, and the mth cantilever beam and the nth cantilever beam are symmetrical with the kth cantilever beam and the lth cantilever beam with respect to the rotation axis.

[0135] Wherein, the piezoelectric functional module includes: kth, lth, mth, and nth piezoelectric functional units, which are respectively arranged on corresponding cantilever beam units.

[0136] Regarding other parts and preparation methods of the MEMS structure of this embodiment, reference may be made to the relevant description of the first embodiment of the MEMS structure, which will not be repeated here.

[0137] Based on the seventh embodiment of the MEMS structure, the present invention further provides a MEMS piezoelectric bionic vector microphone. The MEMS piezoelectric bionic vector microphone of this embodiment includes: Fig.10F The MEMS structure shown; wherein, the kth piezoelectric functional unit and the lth piezoelectric functional unit are connected in parallel to obtain the first electrical signal; the mth piezoelectric functional unit and the nth piezoelectric functional unit are connected in parallel to obtain the second electrical signal, and the first electrical signal and the second electrical signal are differentiated to obtain a sound source localization signal.

[0138] Based on the above embodiments, the symmetric relationship between the N cantilever beam units on the first rotating beam and the N cantilever beam units on the second rotating beam can be summarized as follows:

[0139] ① The two are symmetrical with respect to the rotation axis, as shown in the first, second, fourth and seventh embodiments;

[0140] ② The two are symmetrical with respect to the center point of the detection area, as shown in the first, second, third, fourth, fifth, sixth and seventh embodiments;

[0141] ③ The two are symmetrical with respect to a transverse symmetry axis passing through the center point of the detection area and perpendicular to the rotation axis, as shown in the first, second, fourth and seventh embodiments.

[0142] ④ The two are symmetrical with respect to the rotation axis, but asymmetrical with respect to a transverse symmetry axis passing through the center point of the detection area and perpendicular to the rotation axis.

[0143] ⑤ The two are symmetrical with respect to a transverse symmetry axis passing through the center point of the detection area and perpendicular to the rotation axis, and are asymmetrical with respect to the rotation axis.

[0144] Through the simulation of the above-mentioned embodiments, it is proved that the technical solution of the present invention is applicable to all shapes whose basic structural principles are similar to those of the first embodiment. The "seesaw" structure of any shape is used to sense the sound pressure gradient to produce rotation, and drive the beam units on both sides to produce reverse displacement to output anti-phase electrical signals, and the anti-phase electrical signals are differentiated to achieve accurate measurement of weak sound pressure gradient signals. At the same time, the technical solution of the present invention can also be designed as a double-chip structure of a double-layer piezoelectric layer according to needs. As long as the structure of any shape that meets the above principles is within the protection scope of the present invention.

[0145] Those skilled in the art can adjust the number, position, and symmetry of the cantilever beam units according to actual needs while satisfying the basic principles of the present invention, and all of these can implement the present invention and are within the protection scope of the present invention.

[0146] At this point, the various embodiments of the present invention have been introduced. According to the above description, those skilled in the art should have a clear understanding of the present invention.

[0147] It should be noted that, unless explicitly indicated to the contrary, the numerical parameters in the specification and claims of the present invention may be approximate values ​​and may be changed according to the content of the present invention. Specifically, all the numbers indicating the content of the composition, reaction conditions, etc. recorded in the specification and claims should be understood to be modified by the term "about" in all cases, and the meaning of the expression is to include a change of ±10% from a specific number in some embodiments.

[0148] The ordinal numbers used in the specification and claims, such as "first", "second", "third", "primary", "secondary", as well as Arabic numerals, letters, etc., to modify the corresponding elements are intended only to clearly distinguish an element with a certain name from another element with the same name, and do not mean that the element (or step) has any ordinal number, nor do they represent the order of one element and another element.

[0149] It should also be noted that the directional terms mentioned in the embodiments, such as "center", "lateral", "longitudinal", "top", "bottom", "up", "down", "front", "back", "left", "right", "inside", "outside", etc., indicate positions or positional relationships based only on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Moreover, throughout the drawings, the same elements are represented by the same or similar reference numerals. Moreover, the shapes and sizes of the components in the drawings do not reflect the actual size and proportion, but only illustrate the contents of the embodiments of the present invention.

[0150] Those skilled in the art should understand that in the claims and description of the present invention, the word "comprising" does not exclude the existence of elements (or steps) not listed in the claims. The word "a" or "an" preceding an element (or step) does not exclude the existence of multiple such elements (or steps).

[0151] For certain implementations, if they are not the key content of the present invention and are well known to ordinary technicians in the relevant technical field, they are not described in detail in the drawings or text of the specification due to space limitations. In this case, reference can be made to relevant existing technologies for understanding.

[0152] Furthermore, the above embodiments are provided merely to enable the present invention to satisfy legal requirements, and the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[0153] Similarly, it should be understood that in order to simplify the present invention, in the above description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the invention should not be interpreted as reflecting the following intention: the claimed invention requires more features than the features explicitly stated in each claim. More specifically, as reflected in the claims, each inventive aspect lies in less than all the features of the previous single embodiment. Moreover, the embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present invention.

[0154] The above specific embodiments provide a detailed description of the objectives, technical means and beneficial effects of the present invention. It should be understood that the purpose of the detailed description is to enable those skilled in the art to understand the present invention more clearly, and it is not used to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A MEMS structure, characterized in that: include: The substrate comprises: a substrate outer ring body; a substrate back cavity formed on the inner side of the substrate outer ring body; The vibration layer is formed on the outer ring of the substrate and the back cavity of the substrate, and includes: A fixed area is formed above the outer ring of the substrate; a detection area, formed above the back cavity and separated from the fixing area by a slit; Two rotating connection structures are connected to the detection area at the front and rear sides of the fixed area respectively, and a rotation axis is formed by a straight line of the two rotating connection structures, and the rotation axis divides the detection area into a first rotating beam and a second rotating beam; 2N cantilever beam units, wherein the first rotating beam and the second rotating beam are connected to the fixed area through N cantilever beam units respectively; for each cantilever beam unit, two sides thereof are separated from the fixed area and the detection area by slits, the fixed end thereof is fixedly supported in the fixed area, and the free end thereof is connected to the corresponding detection area through a hinge structure, N≥1; The piezoelectric functional module includes: 2N piezoelectric functional units, which are respectively arranged on corresponding cantilever beam units.

2. The MEMS structure according to claim 1, characterized in that: Both sides of the cantilever beam unit are slits; At the free end of the cantilever beam unit, the slits on both sides extend toward the inner side of the cantilever beam unit to form a first extended slit, so that the width of the free end of the cantilever beam unit becomes narrower to form a connection detail; A semi-sealed slit is formed on one side of the detection area close to the free end or on one side of the fixed end of the cantilever beam unit, wherein the semi-sealed slit is arranged opposite to the connecting detail, and an extension line thereof is parallel to the first extension slit; The first extended slit, the connecting detail, and the semi-sealed slit form the hinge structure.

3. The MEMS structure according to claim 2, characterized in that: The semi-sealed slit is formed on one side of the detection area close to the free end; At the free end of the cantilever beam unit, the slits on both sides extend symmetrically toward the inner side of the cantilever beam unit; Among them, the length of each first extension slit is greater than or equal to 1 / 50 of the width of the cantilever beam unit, the length of the sealing slit is greater than the width of the connecting detail of the cantilever beam unit and less than or equal to 24 / 25 of the width of the cantilever beam unit, and the interval between the first extension slit and the sealing slit is less than or equal to 150μm and greater than or equal to 5μm.

4. The MEMS structure according to claim 1, characterized in that: Both sides of the cantilever beam unit are slits; At the free end of the cantilever beam unit, the slits on both sides extend toward the inner side of the cantilever beam unit but staggered to form a second extended slit, forming a connecting zigzag portion between the free end of the cantilever beam unit and the detection area; Wherein, the second extending slit and the connecting bending part form the hinge structure.

5. The MEMS structure according to claim 4, characterized in that: The length of each second extended slit is greater than 1 / 2 of the width of the cantilever beam unit; The interval between the two second extended slits is less than or equal to 150 μm and greater than or equal to 5 μm.

6. The MEMS structure according to claim 1, characterized in that: For the N cantilever beam units on the first rotating beam and the N cantilever beam units on the second rotating beam, The two are symmetrical with respect to the rotation axis; and / or, the two are symmetrical with respect to the center point of the detection area; And / or, the two are symmetrical with respect to a transverse symmetry axis passing through a center point of the detection area and perpendicular to the rotation axis.

7. The MEMS structure according to claim 6, characterized in that: The substrate back cavity is in the shape of a rectangular parallelepiped as a whole; at the midpoint of the two long sides of the substrate back cavity, the substrate outer ring body and the fixing area extend toward the inner side of the substrate back cavity to form two symmetrical support columns; The rotating connection structure is in the shape of an elongated strip, the lower part of which is connected to the supporting column, and the periphery of which is separated from other parts of the supporting column by a slit; The detection zone portion between the two rotationally connected structures constitutes a rotation beam of the detection zone.

8. The MEMS structure according to claim 7, characterized in that: The horizontal cross-section of the rotary connection structure is rectangular; The length of the rotary connection structure is between 50 μm and 500 μm, and the width is between 10 μm and 100 μm.

9. The MEMS structure according to claim 7, characterized in that: The first rotating beam is connected to the fixed area through the a-th cantilever beam and the b-th cantilever beam; the a-th cantilever beam and the b-th cantilever beam are arranged on a side of the first rotating beam away from the rotating axis, and the two extend in a direction parallel to the rotating axis, and the two are arranged opposite to each other and separated by a preset distance; The second rotating beam is connected to the fixed area through the g-th cantilever beam and the h-th cantilever beam, wherein the g-th cantilever beam is symmetrical with the a-th cantilever beam relative to the rotating axis; and the h-th cantilever beam is symmetrical with the b-th cantilever beam relative to the rotating axis; The piezoelectric functional module comprises: a, b, g, and h piezoelectric functional units, which are respectively arranged on corresponding cantilever beam units.

10. The MEMS structure according to claim 7, characterized in that: The first rotating beam is connected to the upper fixed area through the a-th cantilever beam, or is connected to the lower fixed area in an upper and lower mirror image; the a-th cantilever beam is arranged on a side of the first rotating beam away from the rotating axis and extends in a direction parallel to the rotating axis; The second rotating beam is connected to the lower fixed area through the hth cantilever beam, or is connected to the upper fixed area in an upper and lower mirror image, and the hth cantilever beam is symmetrical with the ath cantilever beam relative to the center point of the detection area; The piezoelectric functional module comprises: a and h piezoelectric functional units, which are respectively arranged on corresponding cantilever beam units.

11. The MEMS structure according to claim 7, characterized in that: The first rotating beam is connected to the fixed area through the c-th cantilever beam and the d-th cantilever beam. The c-th cantilever beam and the d-th cantilever beam are arranged on the side of the first rotating beam close to the rotating axis. The fixed support sections of the two cantilever beams are respectively connected to the fixed layer above the two supporting columns. The two cantilever beams are respectively arranged on the front and rear sides of the first rotating beam, and the two cantilever beams extend in the direction perpendicular to the rotating axis. The second rotating beam is connected to the fixed area through the e-th cantilever beam and the f-th cantilever beam, the e-th cantilever beam and the c-th cantilever beam are symmetrical with respect to the rotating axis; the f-th cantilever beam and the d-th cantilever beam are symmetrical with respect to the rotating axis; The piezoelectric functional module includes: c, d, e, and f piezoelectric functional units, which are respectively arranged on corresponding cantilever beam units.

12. The MEMS structure according to claim 7, characterized in that: The c-th cantilever beam is arranged on one side of the first rotating beam close to the rotating axis, and extends in a direction perpendicular to the rotating axis; the first rotating beam is connected to the fixed layer on the upper supporting column through the c-th cantilever beam, or is connected to the fixed layer on the lower supporting column in an upper and lower mirrored manner; The second rotating beam is connected to the fixed layer on the lower support column through the fth cantilever beam, or is connected to the fixed layer on the upper support column in an upper and lower mirror image, and the fth cantilever beam and the cth cantilever beam are centrally symmetrical with respect to the center point of the detection area; The piezoelectric functional module includes: the cth and fth piezoelectric functional units, which are respectively arranged on corresponding cantilever beam units.

13. The MEMS structure according to claim 7, characterized in that: The first rotating beam is connected to the fixed area through the a, b, c, d cantilever beams, wherein: The a-th cantilever beam and the b-th cantilever beam are arranged on a side of the first rotating beam away from the rotating axis, and the two extend in a direction parallel to the rotating axis, and are arranged opposite to each other and separated by a preset distance; The c-th cantilever beam and the d-th cantilever beam are arranged on one side of the first rotating beam close to the rotating axis, and the fixed ends of the two cantilever beams are respectively connected to the fixed layers above the two supporting columns, and the two cantilever beams are respectively arranged on the front and rear sides of the first rotating beam, and the two cantilever beams extend in a direction perpendicular to the rotating axis; The second rotating beam is connected to the fixed area through the e, f, g, h cantilever beams, where: The g-th cantilever beam is symmetrical with the a-th cantilever beam relative to the rotation axis; the h-th cantilever beam is symmetrical with the b-th cantilever beam relative to the rotation axis; The e-th cantilever beam and the c-th cantilever beam are symmetrical with respect to the rotation axis; the f-th cantilever beam and the d-th cantilever beam are symmetrical with respect to the rotation axis; The piezoelectric functional module includes: piezoelectric functional units a, b, c, d, e, f, g, and h, which are respectively arranged on corresponding cantilever beam units.

14. The MEMS structure according to claim 7, characterized in that: The first rotating beam is connected to the fixed area through the i-th cantilever beam, the i-th cantilever beam is in an L shape or an L shape after the upper and lower mirror transformation, its fixed support end is connected to the fixed layer above one of the support columns, its straight section extends in a direction perpendicular to the rotating axis, its bent section extends along the edge of the first rotating beam away from the rotating axis, and its free end is connected to the first rotating beam; The second rotating beam is connected to the fixed area through the jth cantilever beam, and the jth cantilever beam is centrally symmetrical with the ith cantilever beam about the center point of the detection area; The piezoelectric functional module comprises: i-th and j-th piezoelectric functional units, which are respectively arranged on corresponding cantilever beam units.

15. The MEMS structure according to claim 7, characterized in that: The first rotating beam is connected to the fixed area through the kth cantilever beam and the lth cantilever beam, the kth cantilever beam and the lth cantilever beam are both L-shaped, and the fixed ends of the two cantilever beams are respectively connected to the fixed layers above the two support columns; the free ends of the two cantilever beams are opposite and separated by a preset distance; the straight segments and the bent segments of the two cantilever beams are arranged along the edge of the first rotating beam; the two cantilever beams are symmetrical with respect to a transverse symmetry axis passing through the center point of the detection area and perpendicular to the rotation axis; The second rotating beam is symmetrical to the first rotating beam with respect to the rotating axis; the second rotating beam is connected to the fixed area through the mth cantilever beam and the nth cantilever beam, and the mth cantilever beam and the nth cantilever beam are symmetrical to the kth cantilever beam and the lth cantilever beam with respect to the rotating axis; The piezoelectric functional module includes: kth, lth, mth and nth piezoelectric functional units, which are respectively arranged on corresponding cantilever beam units.

16. The MEMS structure according to any one of claims 1 to 15, characterized in that: The piezoelectric functional unit comprises: a lower electrode layer, a piezoelectric layer, and an upper electrode layer arranged in sequence from bottom to top; wherein: The material of the substrate is: silicon or silicon-based compound; And / or, the material of the vibration layer is one or more of the following materials: silicon, silicon nitride, silicon oxide, piezoelectric material; And / or, the material of the piezoelectric layer, the lower piezoelectric layer, and the upper piezoelectric layer is one or more of the following materials: aluminum nitride, scandium-doped aluminum nitride, zinc oxide, and piezoelectric ceramics, and the thickness thereof ranges from 0.1um to 10um; And / or, the material of the lower electrode layer, the upper electrode layer and the middle electrode layer is one or more of the following materials: molybdenum, gold, aluminum, chromium, and the thickness thereof is in the range of 20nm-200nm; And / or, the length and width of the substrate back cavity range from 0.1 mm to 10 mm, and the aspect ratio is greater than or equal to 4 / 3; and / or, the width of the slit is between 5 μm and 50 μm; And / or, the piezoelectric functional unit includes: a first part located on the cantilever beam unit, a second part located on the fixed area, and the first part is larger than the second part.

17. A preparation method, characterized in that: For preparing a MEMS structure as claimed in any one of claims 7 to 15, comprising: Step A, depositing a sacrificial layer and a vibration layer on a substrate in sequence; Step B, sequentially depositing thin film materials of various layers of the piezoelectric functional unit on the vibration layer; Step C, patterning each layer of thin film material of the piezoelectric functional unit to form 2N piezoelectric functional units; Step D, etching the vibration layer and the sacrificial layer to form the slit; Step E, thinning the back side of the substrate to a preset thickness; Step F, performing deep silicon etching on the back side of the substrate until the sacrificial layer is formed to form a back cavity; Step G, releasing the sacrificial layer, and the slits penetrate the vibration layer to form the detection area, two rotating connection structures, and 2N cantilever beam units.

18. A MEMS piezoelectric bionic vector microphone, characterized in that: include: The MEMS structure as claimed in claim 9; Among them, the signals output by the a and b piezoelectric functional units are connected in parallel as the first electrical signal; the signals output by the g and h piezoelectric functional units are connected in parallel as the fourth electrical signal, and the sound source localization signal is obtained by differentially comparing the first and fourth electrical signals.

19. A MEMS piezoelectric bionic vector microphone, characterized in that: include: The MEMS structure as claimed in claim 10; Among them, the signal output by the ath piezoelectric functional unit is used as the first electrical signal; the signal output by the hth piezoelectric functional unit is used as the fourth electrical signal, and the sound source localization signal is obtained by differentially calculating the first and fourth electrical signals.

20. A MEMS piezoelectric bionic vector microphone, characterized in that: include: The MEMS structure as claimed in claim 11; Among them, the signals output by the cth and dth piezoelectric functional units are connected in parallel as the second electrical signal; the signals output by the eth and fth piezoelectric functional units are connected in parallel as the third electrical signal, and the difference between the second and third electrical signals is used to obtain the sound source localization signal.

21. A MEMS piezoelectric bionic vector microphone, characterized in that: include: The MEMS structure as claimed in claim 12; Among them, the signal output by the cth piezoelectric functional unit is used as the second electrical signal; the signal output by the fth piezoelectric functional unit is used as the third electrical signal, and the sound source localization signal is obtained by differentially calculating the second and third electrical signals.

22. A MEMS piezoelectric bionic vector microphone, characterized in that: include: The MEMS structure as claimed in claim 13; wherein The signals output by the a and b piezoelectric functional units are connected in parallel as the first electrical signal; The signals output by the cth and dth piezoelectric functional units are connected in parallel as the second electrical signal; The signals output by the e-th and f-th piezoelectric functional units are connected in parallel as the third electrical signal; The signals output by the g and h piezoelectric functional units are connected in parallel as the fourth electrical signal; The first and second electrical signals are connected in series to output a fifth electrical signal; The third and fourth electrical signals are connected in series to output a sixth electrical signal; The sound source localization signal is obtained by differentiating the 5th and 6th electrical signals.

23. A MEMS piezoelectric bionic vector microphone, characterized in that: include: The MEMS structure as claimed in claim 14; Among them, the sound source localization signal is obtained by differentiating the signals output by the i-th and j-th piezoelectric functional units.

24. A MEMS piezoelectric bionic vector microphone, characterized in that: include: The MEMS structure as claimed in claim 15; Among them, the kth piezoelectric functional unit and the lth piezoelectric functional unit are connected in parallel to obtain the first electrical signal; the mth piezoelectric functional unit and the nth piezoelectric functional unit are connected in parallel to obtain the second electrical signal, and the sound source localization signal is obtained by differentiating the first electrical signal and the second electrical signal.

Images