A piezoelectric MEMS acoustic transducer and preparation method thereof

Abstract

The present invention discloses a piezoelectric MEMS acoustic transducer and a preparation method, comprising: a substrate and a diaphragm; the diaphragm is located on the surface of the substrate; the substrate comprises a cavity, and the cavity penetrates the substrate along the direction of the substrate pointing to the diaphragm; the surface of the diaphragm away from the substrate is provided with at least two grooves, and the grooves penetrate the diaphragm; the vertical projection of the grooves on the substrate is located in the cavity; a corrugated structure layer is provided in the groove, and the first side wall of the first edge of the corrugated structure layer extends to the surface of the diaphragm away from the substrate, and the second side wall of the second edge of the corrugated structure layer extends to the surface of the diaphragm away from the substrate; the surface of the corrugated structure layer is provided with at least one groove, and / or when the Young's modulus of the material used in the corrugated structure layer is less than a preset value, the surface of the corrugated structure layer is not provided with a groove. The present invention can improve low-frequency attenuation and reduce the stiffness of the diaphragm at the same time.

Description

Technical Field

[0001] The present invention relates to the field of MEMS piezoelectric technology, and in particular to a piezoelectric MEMS acoustic transducer and a preparation method thereof. Background Art

[0002] Micro-Electro-Mechanical-Systems (MEMS) acoustic transducers, such as MEMS microphones and MEMS speakers, have the advantages of miniaturization, low power consumption, and high cost-effectiveness, and have a very broad market in consumer electronics and other fields. Piezoelectric-based MEMS acoustic transducers can be used as both sensors and actuators. The diaphragm of a piezoelectric MEMS microphone can convert the external sound pressure it senses into a voltage signal, and the vibration displacement of the diaphragm of a piezoelectric MEMS speaker when a voltage is applied can generate sound pressure.

[0003] The diaphragm used as the transmitting and receiving unit is designed to produce a larger forced displacement, thereby generating a greater sensitivity or sound pressure level. In the prior art, a groove is usually made on the diaphragm, so that a fully clamped diaphragm becomes a multi-beam or cantilever structure, thereby reducing the diaphragm stiffness and increasing the forced displacement of the diaphragm.

[0004] However, slotting means that vents are introduced on both sides of the diaphragm. The larger the slot area, the more serious the attenuation of low frequencies will be and the more acoustic noise will be introduced. Summary of the invention

[0005] The present invention provides a piezoelectric MEMS acoustic transducer and a preparation method thereof, which can improve low-frequency attenuation and simultaneously reduce the rigidity of a diaphragm.

[0006] According to one aspect of the present invention, an embodiment of the present invention provides a piezoelectric MEMS acoustic transducer, comprising: a substrate and a diaphragm; the diaphragm is located on the surface of the substrate; the substrate comprises a cavity, and the cavity runs through the substrate along the direction of the substrate pointing to the diaphragm;

[0007] At least two grooves are arranged on the surface of the diaphragm away from the substrate, and the grooves penetrate the diaphragm; the vertical projection of the grooves on the substrate is located in the cavity; a corrugated structure layer is arranged in the groove, and the first edge of the corrugated structure layer extends to the surface of the diaphragm away from the substrate along the first side wall of the groove, and the second edge of the corrugated structure layer extends to the surface of the diaphragm away from the substrate along the second side wall of the groove;

[0008] Wherein, the first side wall and the second side wall are arranged opposite to each other along a first direction, and the first direction is the direction from the center of the diaphragm to the slot;

[0009] When at least one groove is arranged on the surface of the corrugated structure layer, and / or when the Young's modulus of the material used for the corrugated structure layer is less than a preset value, no groove is arranged on the surface of the corrugated structure layer.

[0010] Optionally, at least one first groove is provided on a surface of the corrugated structure layer away from the substrate, and / or at least one second groove is provided on a surface of the corrugated structure layer adjacent to the substrate;

[0011] The depth of the first groove is less than the distance between the surface of the corrugated structure layer away from the substrate and the surface of the corrugated structure layer adjacent to the substrate, and the depth of the second groove is less than the distance between the surface of the corrugated structure layer away from the substrate and the surface of the corrugated structure layer adjacent to the substrate;

[0012] The first groove and the second groove both penetrate the corrugated structure layer along the direction in which the grooves extend.

[0013] Optionally, at least one first groove is disposed on a surface of the corrugated structure layer away from the substrate, and at least one second groove is disposed on a surface of the corrugated structure layer adjacent to the substrate, and along the first direction, the first grooves and the second grooves are alternately arranged.

[0014] Optionally, a dimension of the first groove along the first direction is greater than a dimension of the second groove along the first direction;

[0015] The ratio of the size of the slot along the first direction to the size of the diaphragm along the first direction is greater than or equal to 0.5% and less than or equal to 10%;

[0016] The size of the first groove along the first direction is greater than or equal to 3 microns; the size of the second groove along the first direction is greater than or equal to 1 micron; the depths of the first groove and the second groove are greater than 0.05 microns;

[0017] The thickness of the corrugated structure layer is less than or equal to 3 microns.

[0018] Optionally, the material used for the corrugated structure layer includes one of silicon nitride, polysilicon, polymethyl methacrylate, polyimide, epoxy resin and polydimethylsiloxane, wherein the Young's modulus of the epoxy resin and the polydimethylsiloxane is less than a preset value, and the preset value is less than or equal to 3MPa;

[0019] The diaphragm includes a first structural layer, a first electrode layer, a piezoelectric film layer, a second electrode layer and a second structural layer which are stacked in sequence;

[0020] The first structure layer is located on the surface of the substrate; the first electrode layer is arranged on the surface of the first structure layer away from the substrate; the piezoelectric film layer is arranged on the surface of the first electrode layer away from the substrate; and the second electrode layer is arranged on the surface of the piezoelectric film layer away from the substrate.

[0021] Optionally, a third groove is further provided on the surface of the diaphragm; the third groove is located on at least one side of the slot along the second direction, the third groove passes through the diaphragm, and the third groove is connected to the slot, wherein the second direction is the direction in which the slot extends.

[0022] Optionally, a dimension of the third groove along the second direction is greater than or equal to 0.1 micrometers and less than or equal to 5 micrometers.

[0023] Optionally, the surface of the diaphragm is provided with two grooves, the two grooves are symmetrically arranged with respect to the symmetry line of the diaphragm, and each groove is in a strip shape;

[0024] Alternatively, the surface of the diaphragm is provided with four slots, the four slots are evenly distributed along the edge of the diaphragm, the four slots are centrally symmetrical with respect to the geometric center of the diaphragm, and each slot is arc-shaped or L-shaped;

[0025] Alternatively, a groove is provided on the surface of the diaphragm; the groove includes a first sub-groove, a second sub-groove and a third sub-groove connected in sequence, the first sub-groove, the second sub-groove and the third sub-groove are arranged in a U-shape, and the first sub-groove, the second sub-groove and the third sub-groove are interconnected; the first sub-groove is provided with a first sub-corrugated structure layer; the second sub-groove is provided with a second sub-corrugated structure layer; the third sub-groove is provided with a third sub-corrugated structure layer; there is a gap between the first sub-corrugated structure layer and the second sub-corrugated structure layer; there is a gap between the second sub-corrugated structure layer and the third sub-corrugated structure layer.

[0026] According to another aspect of the present invention, an embodiment of the present invention provides a method for preparing a piezoelectric MEMS acoustic transducer, comprising:

[0027] providing a substrate;

[0028] A diaphragm, a corrugated structure layer and a cavity are formed on the surface of the substrate; wherein at least two grooves are arranged on the surface of the diaphragm away from the substrate, and the grooves penetrate the diaphragm; a corrugated structure layer is arranged in the grooves, and a first side wall of the first edge of the corrugated structure layer extends to the surface of the diaphragm away from the substrate, and a second side wall of the second edge of the corrugated structure layer extends to the surface of the diaphragm away from the substrate, and at least one groove is arranged on the surface of the corrugated structure layer, and / or the Young's modulus of the material used for the corrugated structure layer is less than a preset value; wherein the first side wall and the second side wall are arranged relative to each other along a first direction, and the first direction is the direction from the center of the diaphragm to the groove; a cavity is formed on the surface of the substrate away from the diaphragm;

[0029] Wherein, along the direction from the substrate to the diaphragm, the cavity penetrates the substrate; and the vertical projection of the groove on the substrate is located in the cavity.

[0030] Optionally, a diaphragm, a corrugated structure layer and a cavity are formed on the surface of the substrate, including:

[0031] forming a first structural layer on a surface of a substrate;

[0032] forming a first electrode layer on a surface of the first structure layer away from the substrate;

[0033] forming a piezoelectric film layer on a surface of the first electrode layer away from the substrate;

[0034] forming a second electrode layer on a surface of the piezoelectric film layer away from the substrate;

[0035] forming a second structure layer on a surface of the second electrode layer away from the substrate;

[0036] Etching the first structure layer, the first electrode layer, the piezoelectric film layer, the second electrode layer and the second structure layer to form grooves;

[0037] forming a sacrificial layer in the groove;

[0038] Etching the surface of the sacrificial layer away from the substrate to form a concave-convex structure;

[0039] Forming a corrugated structure layer on the surface of the etched sacrificial layer away from the substrate;

[0040] A cavity is formed on the surface of the substrate away from the diaphragm;

[0041] Corroding the surface of the sacrificial layer close to the cavity to remove the sacrificial layer;

[0042] Alternatively, a first structural layer is formed on the surface of the substrate;

[0043] forming a first electrode layer on a surface of the first structure layer away from the substrate;

[0044] forming a piezoelectric film layer on a surface of the first electrode layer away from the substrate;

[0045] forming a second electrode layer on a surface of the piezoelectric film layer away from the substrate;

[0046] forming a second structure layer on a surface of the second electrode layer away from the substrate;

[0047] Etching the first electrode layer, the piezoelectric film layer, the second electrode layer and the second structural layer to form grooves;

[0048] Etching the surface of the first structural layer away from the substrate to form a concave-convex structure;

[0049] Forming a corrugated structure layer on the surface of the etched first structure layer away from the substrate;

[0050] A cavity is formed on the surface of the substrate away from the diaphragm;

[0051] Etching the surface of the first structure layer close to the cavity to remove the first structure layer; or forming the first structure layer on the surface of the substrate;

[0052] forming a first electrode layer on a surface of the first structure layer away from the substrate;

[0053] forming a piezoelectric film layer on a surface of the first electrode layer away from the substrate;

[0054] forming a second electrode layer on a surface of the piezoelectric film layer away from the substrate;

[0055] forming a second structure layer on a surface of the second electrode layer away from the substrate;

[0056] forming a protruding structure on a surface of the first structural layer away from the substrate;

[0057] forming a corrugated structural layer on a surface of the first structural layer away from the substrate;

[0058] A cavity is formed on the surface of the substrate away from the diaphragm; and the surface of the first structural layer close to the cavity is corroded to remove the first structural layer and the protruding structure.

[0059] In the implementation of the present invention, at least two grooves are arranged on the surface of the diaphragm away from the substrate, and the grooves penetrate the diaphragm to reduce the stiffness of the diaphragm. A corrugated structure layer is arranged in the grooves, and at least one groove is arranged on the surface of the corrugated structure layer, and / or the Young's modulus of the material used for the corrugated structure layer is smaller than a preset value. Such an arrangement enhances the flexibility of the corrugated structure layer, and the first side wall of the first edge groove of the corrugated structure layer extends to the surface of the diaphragm away from the substrate, and the second side wall of the second edge groove of the corrugated structure layer extends to the surface of the diaphragm away from the substrate. When the diaphragm is forced to vibrate, the corrugated structure layer is stretched, and the stretched corrugated structure layer can block the grooves and large-area acoustic gaps. The smaller the large-area acoustic gap is, the less serious the attenuation in the low-frequency band is. The present invention not only improves the attenuation in the low-frequency band, but also reduces the stiffness of the diaphragm.

[0060] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0062] Figure 1 is a three-dimensional structural diagram of a piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention;

[0063] Figure 2is a top view of the structure of a piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention;

[0064] Figure 3 yes Figure 1 The cross section along AA1 in the middle;

[0065] Figure 4 yes Figure 2 The cross section along AA1 in the middle;

[0066] Figure 5 is a displacement diagram of the deformation of the diaphragm when the corrugated structure layer provided by the embodiment of the present invention is not connected to the fixed end of the diaphragm;

[0067] Figure 6 is a perspective view of the diaphragm along a first direction under pressure when the corrugated structure layer provided by an embodiment of the present invention is not connected to the fixed end of the diaphragm;

[0068] Figure 7 is a displacement diagram of the deformation of the diaphragm when the corrugated structure layer provided by the embodiment of the present invention is connected to the fixed end of the diaphragm;

[0069] Figure 8 is a perspective view of the diaphragm along a first direction under pressure when the corrugated structure layer provided by an embodiment of the present invention is connected to the fixed end of the diaphragm;

[0070] Fig. 9 is a relationship diagram between frequency and sensitivity of a piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention;

[0071] Fig.10 is a cross-sectional view of the corrugated structure layer along the section line AA1;

[0072] Fig.11 is a top view of the structure of another piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention;

[0073] Fig.12 This is another displacement diagram of the deformation of the diaphragm when the corrugated structure layer is not connected to the fixed end of the diaphragm provided by an embodiment of the present invention;

[0074] Fig.13 This is another displacement diagram of the deformation of the diaphragm when the corrugated structure layer is connected to the fixed end of the diaphragm provided by an embodiment of the present invention;

[0075] Fig.14 is a top view of the structure of another piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention;

[0076] Fig.15 This is another displacement diagram of the deformation of the diaphragm when the corrugated structure layer is not connected to the fixed end of the diaphragm provided by an embodiment of the present invention;

[0077] Fig.16 This is another displacement diagram of the deformation of the diaphragm when the corrugated structure layer is connected to the fixed end of the diaphragm provided by an embodiment of the present invention;

[0078] Fig.17 The embodiment of the present invention also provides a flow chart of a method for preparing a piezoelectric MEMS acoustic transducer;

[0079] Fig.18 is a flow chart of another method for preparing a piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention;

[0080] Figure 19-Figure 26 yes Fig.18 The structural schematic diagram corresponding to each step in the figure;

[0081] Fig. 27 is a flow chart of another method for preparing a piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention;

[0082] Fig.28 yes Fig. 27 The structural diagram corresponding to step S216;

[0083] Fig.29 yes Fig. 27 The structural diagram corresponding to step S217;

[0084] Fig.30 is a flow chart of another method for preparing a piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention;

[0085] Figure 31-Figure 33 yes Fig.30 Schematic diagram of the structure corresponding to step S317. DETAILED DESCRIPTION

[0086] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0087] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, any variation of the terms "including" and "having" is intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0088] Figure 1 It is a three-dimensional structural diagram of a piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention. Figure 2 It is a top view of the structure of a piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention. Figure 3 yes Figure 1 Section along AA1. Figure 4 yes Figure 2 The cross-sectional view along AA1 in FIG. 1 shows a piezoelectric MEMS acoustic transducer, comprising: a substrate 10 and a diaphragm 20; the diaphragm 20 is located on the surface of the substrate 10; the substrate 10 comprises a cavity 11, and the cavity 11 penetrates the substrate 10 along the direction from the substrate 10 to the diaphragm 20; at least two grooves 30 are arranged on the surface of the diaphragm 20 away from the substrate 10, and the grooves 30 penetrate the diaphragm 20; the vertical projection of the grooves 30 on the substrate 10 is located in the cavity 11; a corrugated structure layer 40 is arranged in the groove 30, and the first side of the corrugated structure layer 40 is The first side wall 31 along the groove 30 extends to the surface of the diaphragm 20 away from the substrate 10, and the second side wall 32 along the second edge of the groove 30 of the corrugated structure layer 40 extends to the surface of the diaphragm 20 away from the substrate 10; wherein the first side wall 31 and the second side wall 32 are arranged relatively to each other along a first direction X, and the first direction X is the direction from the center of the diaphragm 20 to the groove; when at least one groove is arranged on the surface of the corrugated structure layer 40, and / or when the Young's modulus of the material used in the corrugated structure layer is less than a preset value, no groove is arranged on the surface of the corrugated structure layer.

[0089] in, Figure 1 and Figure 3The first side wall 31 of the first edge of the corrugated structure layer 40 in the middle groove extends to the surface of the diaphragm 20 away from the substrate 10, and the second side wall 32 of the second edge of the corrugated structure layer 40 extends to the surface of the diaphragm 20 away from the substrate 10. The corrugated structure layer 40 covers the surface of the diaphragm 20 away from the substrate 10. The material used for the substrate 10 is a silicon wafer, and the substrate 10 supports the diaphragm 20. The groove 30 is used to reduce the rigidity of the diaphragm 20. The first side wall 31 of the groove 30 is the fixed end of the diaphragm 20, and the second side wall 32 of the groove 30 is the free end of the diaphragm. The vertical projection shape of the corrugated structure layer 40 in the cavity 11 can be one of a rectangle, a trapezoid, an arc and an L shape.

[0090] When the corrugated structure layer 40 is made of a material with a larger Young's modulus, grooves may be provided on the surface of the corrugated structure layer 40 to increase the flexibility of the corrugated structure layer 40 so that the corrugated structure layer 40 can stretch when the diaphragm 20 vibrates. When the corrugated structure layer 40 is made of a material with a smaller Young's modulus, grooves may not be provided on the surface of the corrugated structure layer 40.

[0091] Exemplarily, the material used for the corrugated structure layer 40 includes one of silicon nitride, polysilicon, polymethyl methacrylate, polyimide, epoxy resin and polydimethylsiloxane. If the material used for the corrugated structure layer 40 includes one of silicon nitride, polysilicon, polymethyl methacrylate and polyimide, the surface of the corrugated structure layer 40 is provided with at least one groove. If the material used for the corrugated structure layer 40 includes one of epoxy resin and polydimethylsiloxane, the surface of the corrugated structure layer 40 may not be provided with grooves or may be provided with at least one groove. The corrugated structure layer 40 is used to block a large area of ​​acoustic gap when the diaphragm 20 is forced to vibrate.

[0092] The first side wall 31 of the first edge groove 30 of the corrugated structure layer 40 extends to the surface of the diaphragm 20 away from the substrate 10, and the second side wall 32 of the second edge groove 30 of the corrugated structure layer 40 extends to the surface of the diaphragm 20 away from the substrate 10, that is, the first edge of the corrugated structure layer 40 is connected to the fixed end of the diaphragm 20, and the second edge of the corrugated structure layer 40 is connected to the free end of the diaphragm 20. When the diaphragm 20 is forced to vibrate, the free end of the diaphragm is greatly deformed, so that the corrugated structure layer 40 is stretched, and the stretched corrugated structure layer 40 will block the large area of ​​acoustic gap exposed when the diaphragm 20 is deformed, so that the attenuation in the low frequency band is small, and because the surface of the corrugated structure layer 40 is provided with a plurality of grooves, and / or the Young's modulus of the material used in the corrugated structure layer 40 is less than the preset value, there is no need to provide grooves on the surface of the corrugated structure layer, and the flexibility of the corrugated structure layer 40 is increased, so that the corrugated structure layer 40 is easily stretched, thereby reducing the influence on the vibration displacement of the diaphragm 20.

[0093] Figure 5is a displacement diagram of the deformation of the diaphragm when the corrugated structure layer provided by the embodiment of the present invention is not connected to the fixed end of the diaphragm; Figure 6 is a perspective view of the diaphragm along a first direction under pressure when the corrugated structure layer provided by an embodiment of the present invention is not connected to the fixed end of the diaphragm; Figure 7 is a displacement diagram of the deformation of the diaphragm when the corrugated structure layer provided by the embodiment of the present invention is connected to the fixed end of the diaphragm; Figure 8 is a perspective view of the diaphragm along a first direction under pressure when the corrugated structure layer provided by an embodiment of the present invention is connected to the fixed end of the diaphragm; for example, see Figure 5 and Figure 6 , where freq=1kHz indicates the number of times the diaphragm moves up and down in a unit time, the scale line on the right indicates the displacement, and the magnitude of the displacement is expressed in microns. When the corrugated structure layer 40 is not connected to the diaphragm fixed end 31, when the diaphragm 20 is forced to vibrate, the free end of the diaphragm is completely free to deform, and the corrugated structure layer 40 will not be stretched. Therefore, the corrugated structure layer 40 cannot block a large area of ​​acoustic gap, and in this case, the maximum vibration displacement of the diaphragm 20 is 78.1 microns. See Figure 7 and Figure 8 When the corrugated structure layer 40 is connected to the diaphragm fixed end 31, when the diaphragm 20 is forced to vibrate, the corrugated structure layer 40 will be stretched, and the stretched corrugated structure layer 40 will block a large area of ​​acoustic gap. At this time, the maximum vibration displacement of the diaphragm 20 is 75.8 microns, which is less than 3% of the maximum vibration displacement of the diaphragm 20 when the corrugated structure layer 40 is not connected to the fixed end of the diaphragm 20. The third direction Z is perpendicular to the first direction X and the second direction Y.

[0094] In the sound transmission path, the acoustic gap is the acoustic resistance R, which is positively correlated to the inverse of the area of ​​the acoustic gap. The volume of the rear chamber of the diaphragm 20 is the acoustic volume C. The acoustic gap and the volume of the rear chamber of the diaphragm 20 constitute a high-pass filter, and its cutoff frequency can be:

[0095]

[0096] When the volume of the back chamber of the 20th layer of the diaphragm remains unchanged, the larger the acoustic gap, the smaller the acoustic resistance R, and the cutoff frequency The higher the value, the stronger the attenuation of the low frequency band. When the acoustic gap is smaller, it means that the acoustic resistance R is larger and the cutoff frequency is The smaller it is, the slower the attenuation of the low frequency band.

[0097] Fig. 9 is a graph showing the relationship between frequency and sensitivity of a piezoelectric MEMS acoustic transducer provided in an embodiment of the present invention, see Fig. 9The red dotted line represents the changing relationship between the frequency and sensitivity of the piezoelectric MEMS acoustic transducer when the corrugated structure layer 40 is connected to the diaphragm fixing end 31; the black solid line represents the changing relationship between the frequency and sensitivity of the piezoelectric MEMS acoustic transducer when the corrugated structure layer 40 is not connected to the diaphragm fixing end 31. The black solid line has a larger attenuation in the low frequency band, and the red dotted line has a smaller attenuation in the low frequency band. This is because when the corrugated structure layer 40 is connected to the diaphragm fixing end 31, the corrugated structure layer 40 blocks the slot 30 and the acoustic gap, and the corresponding low frequency band attenuation is smaller.

[0098] In the implementation of the present invention, at least two grooves 30 are arranged on the surface of the diaphragm 20 away from the substrate 10, and the grooves 30 penetrate the diaphragm 20 to reduce the stiffness of the diaphragm 20. A corrugated structure layer 40 is arranged in the grooves 30. The surface of the corrugated structure layer 40 is provided with at least one groove, and / or the Young's modulus of the material used in the corrugated structure layer 40 is less than a preset value. Such a configuration enhances the flexibility of the corrugated structure layer 40, and the first side wall 31 of the first edge groove 30 of the corrugated structure layer 40 extends to the surface of the diaphragm 20 away from the substrate 10, and the second side wall 32 of the second edge groove 30 of the corrugated structure layer 40 extends to the surface of the diaphragm 20 away from the substrate 10. When the diaphragm 20 is forced to vibrate, the corrugated structure layer 40 is stretched, and the stretched corrugated structure layer 40 can block the grooves 30 and the large-area acoustic gap. The smaller the large-area acoustic gap is, the smaller the low-frequency attenuation is. The present invention not only improves the low-frequency attenuation, but also reduces the stiffness of the diaphragm 20.

[0099] Fig.10 is a cross-sectional view of the corrugated structure layer along the section line AA1, see Figure 1 and Fig.10Optionally, on the basis of the above embodiment, at least one first groove 41 is provided on the surface of the corrugated structure layer 40 away from the substrate 10, and / or at least one second groove 42 is provided on the surface of the corrugated structure layer 40 adjacent to the substrate 10; the depth h2 of the first groove 41 is smaller than the distance h3 between the surface of the corrugated structure layer 40 away from the substrate 10 and the surface of the corrugated structure layer 40 adjacent to the substrate 10, and the depth h2 of the second groove 42 is smaller than the distance h3 between the surface of the corrugated structure layer 40 away from the substrate 10 and the surface of the corrugated structure layer 40 adjacent to the substrate 10; both the first groove 41 and the second groove 42 penetrate the corrugated structure layer 40 along the direction in which the groove 30 extends. Specifically, at least one first groove 41 is provided on the surface of the corrugated structure layer 40 away from the substrate 10, and / or at least one second groove 42 is provided on the surface of the corrugated structure layer 40 adjacent to the substrate 10, so that the cross-section of the corrugated structure layer 40 presents a plurality of concave and / or convex structures, and both the first groove 41 and the second groove 42 penetrate the corrugated structure layer 40 along the direction in which the groove 30 extends, so that the corrugated structure layer 40 has good flexibility, which facilitates the stretching of the corrugated structure layer 40, and when the diaphragm 20 is forced to vibrate, the vibration of the free end of the diaphragm is subject to very little tension from the corrugated structure layer 40, thereby reducing the influence on the vibration displacement.

[0100] Continue to see Figure 1 and Fig.10 Optionally, based on the above embodiment, at least one first groove 41 is provided on the surface of the corrugated structure layer 40 away from the substrate 10, and at least one second groove 42 is provided on the surface of the corrugated structure layer 40 adjacent to the substrate 10, and along the first direction X, the first grooves 41 and the second grooves 42 are alternately arranged.

[0101] Such a configuration makes it easier for the corrugated structure layer 40 to be stretched, and makes the corrugated structure layer 40 more flexible, thereby having less influence on the vibration displacement of the diaphragm 20 .

[0102] Continue to see Fig.10 Optionally, based on the above embodiment, the dimension d of the first groove 41 along the first direction X is greater than the dimension w of the second groove 42 along the first direction X; the dimension d of the first groove 41 along the first direction X is greater than or equal to 3 microns; the dimension w of the second groove 42 along the first direction X is greater than or equal to 1 micron; the depth h2 of the first groove 41 and the second groove 42 is greater than 0.05 microns; the thickness h1 of the corrugated structure layer 40 is less than or equal to 3 microns.

[0103] Specifically, if the dimension d of the first groove 41 along the first direction X is too small, the dimension w of the second groove 42 along the first direction X is too small, and the depth h2 of the first groove 41 and the second groove 42 is too small, the effect of reducing the hardness of the corrugated structure layer 40 is weak, making it difficult to stretch the corrugated structure layer 40. By setting the dimension d of the first groove 41 along the first direction X to be greater than or equal to 3 microns, the dimension w of the second groove 42 along the first direction X to be greater than or equal to 1 micron, and the depth h2 of the first groove 41 and the second groove 42 to be greater than 0.05 microns, the corrugated structure layer 40 has better flexibility and is easier to stretch.

[0104] If the thickness h1 of the corrugated structure layer 40 is too thick, the hardness of the corrugated structure layer 40 is enhanced, making the corrugated structure layer 40 difficult to be stretched. By setting the thickness h1 of the corrugated structure layer 40 to be less than or equal to 0.5 microns, the hardness of the corrugated structure layer 40 is reduced and it is easy to be stretched.

[0105] See also Figure 2 Optionally, based on the above embodiment, the ratio of the size of the slot 30 along the first direction X to the size of the diaphragm 20 along the first direction X is greater than or equal to 0.5% and less than or equal to 10%.

[0106] Specifically, if the ratio of the size of the slot 30 along the first direction X to the size of the diaphragm 20 along the first direction X is too small, the reduction in the rigidity of the diaphragm 20 is small. If the ratio of the size of the slot 30 along the first direction X to the size of the diaphragm 20 along the first direction X is too large, the area of ​​the slot 30 will increase, making the corrugated structure layer 40 easy to break when deformed. Therefore, by setting the ratio of the size of the slot 30 along the first direction X to the size of the diaphragm 20 along the first direction X to be greater than or equal to 0.5% and less than or equal to 10%, the rigidity of the diaphragm 20 can be reduced, and the corrugated structure layer 40 can be prevented from being easily broken when deformed.

[0107] See also Figure 4 Optionally, on the basis of the above embodiments, the material used for the corrugated structure layer 40 includes one of silicon nitride, polysilicon, polymethyl methacrylate, polyimide, epoxy resin and polydimethylsiloxane, wherein the Young's modulus of epoxy resin and polydimethylsiloxane is less than a preset value, and the preset value is less than or equal to 3MPa; the diaphragm 20 includes a first structure layer 21, a first electrode layer 22, a piezoelectric film layer 23, a second electrode layer 24 and a second structure layer 25 which are stacked in sequence; the first structure layer 21 is located on the surface of the substrate 10; the first electrode layer 22 is arranged on the surface of the first structure layer 21 away from the substrate 10; the piezoelectric film layer 23 is arranged on the surface of the first electrode layer 22 away from the substrate 10; the second electrode layer 24 is arranged on the surface of the piezoelectric film layer 23 away from the substrate 10.

[0108] Among them, the materials used for the first structure layer 21 and the second structure layer 25 are oxides or nitrides. The first structure layer 21 and the second structure layer 25 are used to insulate and prevent the first electrode layer 22 and the second electrode layer 24 from being oxidized. The first electrode layer 22 is used for grounding, the second electrode layer 24 is used as a positive electrode, and the piezoelectric film layer 23 is used to vibrate when a voltage signal is applied to the second electrode layer 24.

[0109] Specifically, when the material used for the corrugated structure layer 40 is one of silicon nitride, polysilicon, polymethyl methacrylate and polyimide, at least one groove is set on the surface of the corrugated structure layer 40 to reduce the rigidity of the corrugated structure layer. If the material used for the corrugated structure layer 40 is one of epoxy resin and polydimethylsiloxane, no grooves may be set on the surface of the corrugated structure layer 40, or at least one groove may be set. This arrangement makes the corrugated structure layer 40 more flexible and has less impact on the vibration displacement of the diaphragm 20.

[0110] See also Figure 2 Optionally, on the basis of the above embodiment, a third groove 50 is further provided on the surface of the diaphragm 20; the third groove 50 is located on at least one side of the groove 30 along the second direction Y, the third groove 50 passes through the diaphragm 20, and the third groove 50 is connected with the groove 30, wherein the second direction Y is the direction in which the groove 30 extends.

[0111] The third groove 50 is used to reduce the resistance between the corrugated structure layer 40 and the second fixed end 33 of the diaphragm when the corrugated structure layer 40 is stretched. The second fixed end 33 of the diaphragm is located on both sides of the slot 30 along the second direction Y.

[0112] In the embodiment of the present invention, the third groove 50 is provided to reduce the resistance of the second fixed end 33 of the diaphragm to the corrugated structure layer 40 , thereby reducing the influence on the maximum vibration displacement of the diaphragm 20 .

[0113] Continue to see Figure 2 Optionally, based on the above embodiment, the size of the third groove 50 along the second direction Y is greater than or equal to 0.1 microns and less than or equal to 5 microns.

[0114] Specifically, if the size of the third groove along the second direction Y is too large, the area of ​​the slot 30 will increase, and the acoustic gap will be increased, resulting in a larger attenuation in the low-frequency band. By setting the size of the third groove 50 along the second direction Y to be greater than or equal to 0.1 microns and less than or equal to 5 microns, the resistance of the second fixed end 33 of the diaphragm to the corrugated structure layer 40 is reduced, and the attenuation in the low-frequency band is also reduced.

[0115] See also Figure 1 and Figure 2Optionally, based on the above embodiment, two slots 30 are provided on the surface of the diaphragm 20, and the two slots 30 are symmetrically arranged with respect to the symmetry line of the diaphragm 20, and each slot 30 is in a strip shape.

[0116] Among them, a corrugated structure layer 40 is arranged in the groove, one end of the corrugated structure layer 40 is connected to the fixed end 31 of the diaphragm, and the other end of the corrugated structure layer 40 is connected to the free end of the diaphragm. When the corrugated structure layer 40 is not connected to the fixed end 31 of the diaphragm, the maximum vibration displacement of the diaphragm 20 is 78.1 microns. When the diaphragm 20 vibrates, the corrugated structure layer 40 will not be stretched, and a larger acoustic gap will be generated. When the corrugated structure layer 40 is connected to the fixed end 31 of the diaphragm, the stretched corrugated structure layer 40 will block the large area of ​​the acoustic gap, reducing the attenuation of the low frequency band. At the same time, two grooves 30 are arranged on the surface of the diaphragm 20 to reduce the stiffness of the diaphragm 20.

[0117] Fig.11 is a top view of the structure of another piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention, Fig.12 is another displacement diagram of the deformation of the diaphragm when the corrugated structure layer is not connected to the fixed end of the diaphragm provided by an embodiment of the present invention. Fig.13 is another displacement diagram of the deformation of the diaphragm when the corrugated structure layer is connected to the fixed end of the diaphragm provided by an embodiment of the present invention, see Figure 11-13 Optionally, based on the above embodiment, four slots 30 are provided on the surface of the diaphragm 20, the four slots 30 are evenly distributed along the edge of the diaphragm 20, the four slots 30 are symmetrical with respect to the geometric center of the diaphragm 20, and each slot 30 is arc-shaped or L-shaped;

[0118] Specifically, Fig.12 As shown, the four slots 30 are each provided with a corrugated structure layer 40, one end of the corrugated structure layer 40 is connected to the diaphragm fixed end 31, and the other end of the corrugated structure layer 40 is connected to the diaphragm free end. When the corrugated structure layer 40 is not connected to the diaphragm fixed end 31, the maximum vibration displacement of the diaphragm 20 is 18.5um, and the vibration of the diaphragm will produce a large acoustic gap. Fig.13 As shown, when the corrugated structure layer 40 is connected to the diaphragm fixed end 31, the maximum displacement of the diaphragm 20 is 18.1 microns. At this time, the corrugated structure layer 40 is stretched, and the stretched corrugated structure layer 40 in the four grooves 30 blocks the large area of ​​the acoustic gap, reducing the attenuation of the low frequency band. At the same time, four grooves 30 are arranged on the surface of the diaphragm 20 to reduce the stiffness of the diaphragm 20.

[0119] Fig.14 This is a top view of the structure of another piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention. Fig.15This is another displacement diagram of the deformation of the diaphragm when the corrugated structure layer is not connected to the fixed end of the diaphragm, provided by an embodiment of the present invention. Fig.16 This is another displacement diagram of the deformation of the diaphragm when the corrugated structure layer is connected to the fixed end of the diaphragm provided by an embodiment of the present invention. Figure 14-16 Optionally, on the basis of the above embodiment, a groove 30 is provided on the surface of the diaphragm 20; the groove 30 includes a first sub-groove 301, a second sub-groove 302 and a third sub-groove 303 connected in sequence, the first sub-groove 301, the second sub-groove 302 and the third sub-groove 303 are arranged in a U shape, and the first sub-groove 301, the second sub-groove 302 and the third sub-groove 303 are interconnected; the first sub-groove 301 is provided with a first sub-corrugated structure layer 401; the second sub-groove 302 is provided with a second sub-corrugated structure layer 402; the third sub-groove 303 is provided with a third sub-corrugated structure layer 403; there is a gap between the first sub-corrugated structure layer 401 and the second sub-corrugated structure layer 402; there is a gap between the second sub-corrugated structure layer 402 and the third sub-corrugated structure layer 403.

[0120] Specifically, Fig.15 As shown, the first end of the first sub-corrugated structure layer 401, the first end of the second sub-corrugated structure layer 402 and the first end of the third sub-corrugated structure layer 403 are all connected to the diaphragm fixed end 31, and the second end of the first sub-corrugated structure layer 401, the second end of the second sub-corrugated structure layer 402 and the second end of the third sub-corrugated structure layer 403 are all connected to the diaphragm free end; when the first end of the first sub-corrugated structure layer 401, the first end of the second sub-corrugated structure layer 402 and the first end of the third sub-corrugated structure layer 403 are not connected to the diaphragm fixed end 31, when the diaphragm 20 vibrates, the maximum vibration displacement of the diaphragm 20 is 58.5 microns, and the diaphragm 20 will expose a large area of ​​acoustic gap. When the first end of the structural layer 401, the first end of the second sub-corrugated structural layer 402 and the first end of the third sub-corrugated structural layer 403 are all connected to the diaphragm fixed end 31, the diaphragm 20 produces a maximum vibration displacement of 57.1 microns. At this time, the first sub-corrugated structural layer 401, the second sub-corrugated structural layer 402 and the third sub-corrugated structural layer 403 will all be stretched. The stretched first sub-corrugated structural layer 401, the second sub-corrugated structural layer 402 and the third sub-corrugated structural layer 403 will all block the large-area acoustic gap generated when the diaphragm 20 vibrates, and the first sub-groove 301, the second sub-groove 302 and the third sub-groove 303 are arranged on the surface of the diaphragm 20, thereby reducing the stiffness of the diaphragm 20.

[0121] The embodiment of the present invention also provides a method for preparing a piezoelectric MEMS acoustic transducer. Fig.17 is a flow chart of a method for preparing a piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention, see Fig.17, the preparation method of the piezoelectric MEMS acoustic transducer comprises:

[0122] S110, providing a substrate.

[0123] S120, forming a diaphragm, a corrugated structure layer and a cavity on the surface of the substrate.

[0124] Wherein, at least two grooves are arranged on the surface of the diaphragm away from the substrate, and the grooves penetrate the diaphragm; a corrugated structure layer is arranged in the groove, and the first side wall of the first edge groove of the corrugated structure layer extends to the surface of the diaphragm away from the substrate, and the second side wall of the second edge groove of the corrugated structure layer extends to the surface of the diaphragm away from the substrate, and at least one groove is arranged on the surface of the corrugated structure layer, and / or when the Young's modulus of the material used for the corrugated structure layer is less than a preset value, no groove is arranged on the surface of the corrugated structure layer; wherein the first side wall and the second side wall are arranged relative to each other along a first direction X, and the first direction X is the direction from the center of the diaphragm to the groove; a cavity is formed on the surface of the substrate away from the diaphragm; wherein the cavity penetrates the substrate along the direction from the substrate to the diaphragm; and the vertical projection of the groove on the substrate is located in the cavity.

[0125] In the implementation of the present invention, at least two grooves are arranged on the surface of the diaphragm away from the substrate, and the grooves penetrate the diaphragm to reduce the stiffness of the diaphragm. A corrugated structure layer is arranged in the grooves, and at least one groove is arranged on the surface of the corrugated structure layer, and / or the Young's modulus of the material used for the corrugated structure layer is less than a preset value, and no grooves are arranged on the surface of the corrugated structure layer. Such a configuration enhances the flexibility of the corrugated structure layer, and the first side wall of the first edge groove of the corrugated structure layer extends to the surface of the diaphragm away from the substrate, and the second side wall of the second edge groove of the corrugated structure layer extends to the surface of the diaphragm away from the substrate. When the diaphragm is forced to vibrate, the corrugated structure layer is stretched, and the stretched corrugated structure layer can block the grooves and large-area acoustic gaps. The smaller the large-area acoustic gap is, the less serious the low-frequency attenuation is. The present invention not only improves the low-frequency attenuation, but also reduces the stiffness of the diaphragm.

[0126] Fig.18 This is a flow chart of another method for preparing a piezoelectric MEMS acoustic transducer provided in an embodiment of the present invention. Figure 19-Figure 26 yes Fig.18 The structural diagram corresponding to each step in Fig.18 Optionally, based on the above embodiment, the method for preparing the piezoelectric MEMS acoustic transducer includes:

[0127] S110, providing a substrate.

[0128] See also Fig.19 , a substrate 10 is provided.

[0129] S1201, forming a first structural layer on the surface of the substrate.

[0130] See also Fig. 20 , a first structure layer 21 is formed on the surface of the substrate 10 by a thermal oxidation process or a chemical vapor deposition process.

[0131] S1202 , forming a first electrode layer on a surface of the first structure layer away from the substrate.

[0132] See also Fig. 20 A first electrode layer 22 is formed on a surface of the first structure layer 21 away from the substrate 10 by a physical vapor deposition process.

[0133] S1203, forming a piezoelectric film layer on a surface of the first electrode layer away from the substrate.

[0134] See also Fig. 20 A piezoelectric film layer 23 is formed on a surface of the first electrode layer 22 away from the substrate 10 by physical vapor deposition, chemical vapor deposition or sol-gel method.

[0135] S1204, forming a second electrode layer on a surface of the piezoelectric film layer away from the substrate.

[0136] See also Fig. 20 A second electrode layer 24 is formed on a surface of the piezoelectric film layer 23 away from the substrate 10 by a physical vapor deposition process.

[0137] S1205 , forming a second structure layer on a surface of the second electrode layer away from the substrate.

[0138] See also Fig. 20 A second structure layer 25 is formed on a surface of the second electrode layer 24 away from the substrate 10 by a physical vapor deposition process or a chemical vapor deposition process.

[0139] S1206, etching the first structure layer, the first electrode layer, the piezoelectric film layer, the second electrode layer and the second structure layer to form grooves.

[0140] See also Fig.21 The first structure layer 21, the first electrode layer 22, the piezoelectric film layer 23, the second electrode layer 24 and the second structure layer 25 are etched by a wet etching or dry etching process to form a groove 30.

[0141] S1207, forming a sacrificial layer in the groove.

[0142] See also Fig. 22 A sacrificial layer 26 is formed in the groove 30 and on the surface of the second structure layer 25 away from the substrate 10 by a physical vapor deposition process or a chemical vapor deposition process, wherein the material used for the sacrificial layer 26 is oxide.

[0143] See also Fig.23The sacrificial layer 26 on the surface of the second structure layer 25 away from the substrate 10 is etched by a dry etching process or a wet etching process.

[0144] S1208, etching the surface of the sacrificial layer in the groove away from the substrate to form a concave-convex structure.

[0145] See also Fig.24 The sacrificial layer 26 is etched by a dry etching process and a dry etching rate is controlled to form a concave-convex structure 260 .

[0146] S1209, forming a corrugated structure layer on the surface of the etched sacrificial layer away from the substrate.

[0147] See also Fig.25 A corrugated structure layer 40 is formed on the surface of the etched sacrificial layer 26 away from the substrate 10 .

[0148] S1210. Form a cavity on a surface of the substrate away from the diaphragm.

[0149] See also Fig.26 A cavity 11 is formed on the surface of the substrate 10 away from the diaphragm by deep reactive ion etching process.

[0150] S1211. Corrode the surface of the sacrificial layer close to the cavity to remove the sacrificial layer.

[0151] See also Figure 4 and Fig.26 When removing the sacrificial layer 26, it is necessary to coat the surface of the first structure layer 21 close to the cavity 11 and the surface of the substrate 10 close to the cavity 11 with a protective layer, and use vapor hydrofluoric acid (Vapor-HF, VHF) or buffered-oxide-etchant (BOE) to etch the sacrificial layer 26 to form Figure 4 The piezoelectric MEMS acoustic transducer shown.

[0152] Fig. 27 is a flow chart of another method for preparing a piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention. Fig.28 yes Fig. 27 The structural diagram corresponding to step S216, Fig.29 yes Fig. 27 The structural diagram corresponding to step S217 in FIG. Fig. 27 Optionally, based on the above embodiment, the method for preparing the piezoelectric MEMS acoustic transducer includes:

[0153] S210, providing a substrate.

[0154] S211, forming a first structural layer on the surface of the substrate.

[0155] S212, forming a first electrode layer on a surface of the first structure layer away from the substrate.

[0156] S213, forming a piezoelectric film layer on a surface of the first electrode layer away from the substrate.

[0157] S214, forming a second electrode layer on a surface of the piezoelectric film layer away from the substrate.

[0158] S215, forming a second structure layer on a surface of the second electrode layer away from the substrate.

[0159] The preparation process and effects of S210-S215 refer to S110-S1211 and will not be repeated here.

[0160] S216, etching the first electrode layer, the piezoelectric film layer, the second electrode layer and the second structural layer to form grooves.

[0161] See also Fig.28 The first electrode layer 22, the piezoelectric film layer 23, the second electrode layer 24 and the second structure layer 25 are etched by a wet etching or dry etching process to form a groove 30.

[0162] S217, etching the surface of the first structure layer away from the substrate to form a concave-convex structure.

[0163] See also Fig.29 , the surface of the first structure layer 21 away from the substrate 10 is etched by a wet etching or dry etching process to form a concave-convex structure 260 .

[0164] S218, forming a corrugated structure layer on the surface of the etched first structure layer away from the substrate.

[0165] S219. Form a cavity on the surface of the substrate away from the diaphragm.

[0166] See also Fig.26 A cavity 11 is formed on the surface of the substrate 10 away from the diaphragm by deep reactive ion etching process.

[0167] S220, corroding the surface of the first structure layer close to the cavity to remove the first structure layer.

[0168] Fig.30 is a flow chart of another method for preparing a piezoelectric MEMS acoustic transducer provided by an embodiment of the present invention. Fig.31 and Fig.33 yes Fig.30 The structural diagram corresponding to step S317 in FIG. Fig.30 Optionally, based on the above embodiment, the method for preparing the piezoelectric MEMS acoustic transducer includes:

[0169] S310, providing a substrate.

[0170] S311, forming a first structural layer on the surface of the substrate.

[0171] S312, forming a first electrode layer on a surface of the first structure layer away from the substrate.

[0172] S313, forming a piezoelectric film layer on a surface of the first electrode layer away from the substrate.

[0173] S314, forming a second electrode layer on a surface of the piezoelectric film layer away from the substrate.

[0174] S315, forming a second structure layer on a surface of the second electrode layer away from the substrate.

[0175] The preparation process and effects of S310-S315 refer to S110-S1211 and will not be repeated here.

[0176] S316, etching the first electrode layer, the piezoelectric film layer, the second electrode layer and the second structural layer to form grooves.

[0177] S317, forming a protruding structure on a surface of the first structural layer away from the substrate.

[0178] The protruding structure 261 is a film layer newly added on the surface of the first structure layer 21 away from the substrate 10 .

[0179] See also Fig.31 A sacrificial layer 26 is formed on a surface of the first structure layer 21 away from the substrate 10 and a surface of the second structure layer 25 away from the substrate 10 by a physical vapor deposition process or a chemical vapor deposition process.

[0180] See also Fig.32 The sacrificial layer 26 on the surface of the second structure layer 25 away from the substrate 10 is etched by a dry etching process or a wet etching process.

[0181] See also Fig.33 , the sacrificial layer on the surface of the first structure layer 21 away from the substrate 10 is etched to form a protruding structure 261 .

[0182] S318, forming a corrugated structural layer on the surface of the first structural layer away from the substrate.

[0183] S319. Form a cavity on the surface of the substrate away from the diaphragm.

[0184] S320, corroding the surface of the first structure layer close to the cavity to remove the first structure layer and the protruding structure.

[0185] The preparation process and effects of S318-S320 refer to S218-S220 and will not be repeated here.

[0186] The method for preparing the piezoelectric MEMS acoustic transducer of the embodiment of the present invention and the piezoelectric MEMS acoustic transducer provided in any embodiment of the present invention belong to the same inventive concept and have corresponding beneficial effects. For technical details not detailed in this embodiment, please refer to the piezoelectric MEMS acoustic transducer provided in any embodiment of the present invention.

[0187] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0188] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A piezoelectric MEMS acoustic transducer, characterized in that: include: Base and diaphragm; The diaphragm is located on the surface of the substrate; The substrate comprises a cavity, which is directed along the substrate to the diaphragm, and the cavity penetrates the substrate; At least two grooves are arranged on the surface of the diaphragm away from the substrate, and the grooves penetrate the diaphragm; the vertical projection of the grooves on the substrate is located in the cavity; a corrugated structure layer is arranged in the groove, and the first edge of the corrugated structure layer extends along the first side wall of the groove to the surface of the diaphragm away from the substrate, and the second edge of the corrugated structure layer extends along the second side wall of the groove to the surface of the diaphragm away from the substrate; Wherein, the first side wall and the second side wall are arranged opposite to each other along a first direction, and the first direction is the direction from the center of the diaphragm to the slot; The surface of the corrugated structure layer is provided with at least one groove, and / or when the Young's modulus of the material used for the corrugated structure layer is less than a preset value, the surface of the corrugated structure layer is not provided with a groove.

2. The piezoelectric MEMS acoustic transducer according to claim 1, characterized in that: The surface of the corrugated structure layer away from the substrate is provided with at least one first groove, and / or the surface of the corrugated structure layer adjacent to the substrate is provided with at least one second groove; The depth of the first groove is smaller than the distance between the surface of the corrugated structure layer away from the substrate and the surface of the corrugated structure layer adjacent to the substrate, and the depth of the second groove is smaller than the distance between the surface of the corrugated structure layer away from the substrate and the surface of the corrugated structure layer adjacent to the substrate; The first groove and the second groove both penetrate the corrugated structure layer along the direction in which the groove extends.

3. The piezoelectric MEMS acoustic transducer according to claim 2, characterized in that: The surface of the corrugated structure layer away from the substrate is provided with at least one first groove, and the surface of the corrugated structure layer adjacent to the substrate is provided with at least one second groove, and along the first direction, the first groove and the second groove are alternately arranged.

4. The piezoelectric MEMS acoustic transducer according to claim 2, characterized in that: The dimension of the first groove along the first direction is greater than the dimension of the second groove along the first direction; The ratio of the dimension of the slot along the first direction to the dimension of the diaphragm along the first direction is greater than or equal to 0.5% and less than or equal to 10%; The size of the first groove along the first direction is greater than or equal to 3 microns; the size of the second groove along the first direction is greater than or equal to 1 micron; the depths of the first groove and the second groove are greater than 0.05 microns; The thickness of the corrugated structure layer is less than or equal to 3 microns.

5. The piezoelectric MEMS acoustic transducer according to claim 1, characterized in that: The preset value is less than or equal to 3MPa; The material used for the corrugated structure layer includes one of silicon nitride, polysilicon, polymethyl methacrylate, polyimide, epoxy resin and polydimethylsiloxane, wherein the Young's modulus of epoxy resin and polydimethylsiloxane is less than the preset value; The diaphragm comprises a first structural layer, a first electrode layer, a piezoelectric film layer, a second electrode layer and a second structural layer which are stacked in sequence; The first structural layer is located on the surface of the substrate; the first electrode layer is arranged on the surface of the first structural layer away from the substrate; the piezoelectric film layer is arranged on the surface of the first electrode layer away from the substrate; and the second electrode layer is arranged on the surface of the piezoelectric film layer away from the substrate.

6. The piezoelectric MEMS acoustic transducer according to claim 1, characterized in that: A third groove is also provided on the surface of the diaphragm; the third groove is located on at least one side of the slot along the second direction, the third groove passes through the diaphragm, and the third groove is connected to the slot, wherein the second direction is the direction in which the slot extends.

7. The piezoelectric MEMS acoustic transducer according to claim 6, characterized in that: A dimension of the third groove along the second direction is greater than or equal to 0.1 micrometers and less than or equal to 5 micrometers.

8. The piezoelectric MEMS acoustic transducer according to claim 1, characterized in that: The surface of the diaphragm is provided with two grooves, the two grooves are symmetrically arranged relative to the symmetry line of the diaphragm, and each of the grooves is in a strip shape; Alternatively, the surface of the diaphragm is provided with four grooves, the four grooves are evenly distributed along the edge of the diaphragm, the four grooves are centrally symmetrical with respect to the geometric center of the diaphragm, and each of the grooves is arc-shaped or L-shaped; Alternatively, a groove is provided on the surface of the diaphragm; the groove includes a first sub-groove, a second sub-groove and a third sub-groove connected in sequence, the first sub-groove, the second sub-groove and the third sub-groove are arranged in a U-shape, and the first sub-groove, the second sub-groove and the third sub-groove are interconnected; the first sub-groove is provided with a first sub-corrugated structure layer; the second sub-groove is provided with a second sub-corrugated structure layer; the third sub-groove is provided with a third sub-corrugated structure layer; there is a gap between the first sub-corrugated structure layer and the second sub-corrugated structure layer; there is a gap between the second sub-corrugated structure layer and the third sub-corrugated structure layer.

9. A method for preparing a piezoelectric MEMS acoustic transducer, characterized in that: include: providing a substrate; A diaphragm, a corrugated structure layer and a cavity are formed on the surface of the substrate; wherein at least two grooves are arranged on the surface of the diaphragm away from the substrate, and the grooves penetrate the diaphragm; a corrugated structure layer is arranged in the groove, and a first edge of the corrugated structure layer extends along a first side wall of the groove to the surface of the diaphragm away from the substrate, and a second edge of the corrugated structure layer extends along a second side wall of the groove to the surface of the diaphragm away from the substrate, and at least one groove is arranged on the surface of the corrugated structure layer, and / or when the Young's modulus of the material used for the corrugated structure layer is less than a preset value, no groove is arranged on the surface of the corrugated structure layer; wherein the first side wall and the second side wall are arranged relative to each other along a first direction, and the first direction is the direction from the center of the diaphragm to the groove; a cavity is formed on the surface of the substrate away from the diaphragm; Wherein, along the direction from the substrate to the diaphragm, the cavity penetrates the substrate; and the vertical projection of the groove on the substrate is located in the cavity.

10. The method for preparing a piezoelectric MEMS acoustic transducer according to claim 9, characterized in that: A diaphragm, a corrugated structure layer and a cavity are formed on the surface of the substrate, including: forming a first structural layer on the surface of the substrate, forming a first electrode layer on a surface of the first structural layer away from the substrate, forming a piezoelectric film layer on a surface of the first electrode layer away from the substrate; forming a second electrode layer on a surface of the piezoelectric film layer away from the substrate, forming a second structure layer on a surface of the second electrode layer away from the substrate, The first structure layer, the first electrode layer, the piezoelectric film layer, the second electrode layer and the second structure layer are etched to form grooves, forming a sacrificial layer in the groove, The surface of the sacrificial layer away from the substrate is etched to form a concave-convex structure, A corrugated structure layer is formed on the surface of the etched sacrificial layer away from the substrate, A cavity is formed on the surface of the substrate away from the diaphragm. Corroding the surface of the sacrificial layer close to the cavity to remove the sacrificial layer; or, forming a first structural layer on the surface of the substrate, forming a first electrode layer on a surface of the first structural layer away from the substrate, forming a piezoelectric film layer on a surface of the first electrode layer away from the substrate; forming a second electrode layer on a surface of the piezoelectric film layer away from the substrate, forming a second structure layer on a surface of the second electrode layer away from the substrate, The first electrode layer, the piezoelectric film layer, the second electrode layer and the second structural layer are etched to form grooves, The surface of the first structural layer away from the substrate is etched to form a concave-convex structure, A corrugated structure layer is formed on the surface of the first structure layer away from the substrate after etching, A cavity is formed on the surface of the substrate away from the diaphragm. Etching the surface of the first structural layer close to the cavity to remove the first structural layer; or, forming a first structural layer on the surface of the substrate, forming a first electrode layer on a surface of the first structural layer away from the substrate, forming a piezoelectric film layer on a surface of the first electrode layer away from the substrate; forming a second electrode layer on a surface of the piezoelectric film layer away from the substrate, forming a second structure layer on a surface of the second electrode layer away from the substrate, The first electrode layer, the piezoelectric film layer, the second electrode layer and the second structural layer are etched to form grooves, A protruding structure is formed on a surface of the first structural layer away from the substrate, A corrugated structure layer is formed on the surface of the first structure layer away from the substrate, A cavity is formed on the surface of the substrate away from the diaphragm. The surface of the first structural layer close to the cavity is corroded to remove the first structural layer and the protruding structure.

Images