Piezoelectric structure, cantilever type microphone and preparation method of piezoelectric structure

Abstract

The invention provides a piezoelectric structure, a cantilever type microphone and a preparation method of the piezoelectric structure, and relates to the technical field of semiconductors. The piezoelectric structure comprises a piezoelectric composite laminated layer, the surface of the piezoelectric composite laminated layer is provided with at least one groove group, the groove group comprises at least two grooves, and the at least two grooves are sequentially arranged along a direction opposite to a first direction and are communicated with each other; in the direction opposite to the first direction, the width of the previous groove is larger than that of the next groove, and one side face of the previous groove is flush with one side face of the next groove. According to the piezoelectric structure, the stepped groove group is arranged in the piezoelectric composite laminated layer, so that the gap of which the width is smaller than that of the groove is formed in the piezoelectric composite laminated layer. During processing, the width of a single groove is not required to be as small as possible, so that a gap with the width as small as possible can be easily obtained. The smaller the width of the gap is, the wider the low-frequency response of the cantilever type microphone is.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a piezoelectric structure, a cantilever microphone, and a method for preparing the piezoelectric structure. Background Art

[0002] As an advanced acoustic sensor technology, the cantilever microphone has been rapidly developed due to its many advantages such as low power consumption, fast response, and high reliability. The cantilever microphone is mainly composed of a piezoelectric unit and an ASIC circuit, wherein the piezoelectric unit includes a substrate, a support structure and a piezoelectric structure arranged on the substrate in sequence. The piezoelectric structure includes at least two electrode layers and at least one piezoelectric layer alternately stacked, and a gap is arranged on the piezoelectric structure, and the gap penetrates the piezoelectric structure to form a cantilever beam.

[0003] The design of the gap has a great influence on the low-frequency response of the cantilever microphone. Among them, the gap width is a parameter that directly affects the low-frequency response of the cantilever microphone. The smaller the gap width, the lower the low-frequency response of the cantilever microphone and the wider the response range. A smaller gap width can help the cantilever microphone capture and reproduce low-frequency sounds more accurately, and achieve a wider frequency response to achieve a more natural and clear sound sensing of the cantilever microphone system.

[0004] However, in the actual processing of cantilever microphones, it is extremely difficult to obtain the smallest possible slit width due to the large aspect ratio of the slit to be processed and the presence of difficult-to-etch piezoelectric materials. As the thickness of the cantilever beam increases, the difficulty of processing the slit increases further. In addition, the existing process itself has its own limitations, and it is extremely difficult to process a slit with the smallest possible width. Summary of the invention

[0005] The purpose of the present application is to provide a piezoelectric structure, a cantilever microphone and a method for preparing a piezoelectric structure in view of the deficiencies in the above-mentioned prior art, which can easily obtain a gap with the smallest possible width.

[0006] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0007] According to a first aspect of an embodiment of the present application, a piezoelectric structure is provided, comprising: a piezoelectric composite stack, the piezoelectric composite stack comprising a plurality of film layers, the plurality of film layers being stacked along a first direction, the surface of the piezoelectric composite stack being provided with at least one group of groove groups, the groove groups penetrating two surfaces of the piezoelectric composite stack opposite to each other in the first direction, so as to divide the piezoelectric composite stack into at least two cantilever beams; the groove group comprising at least two grooves, the at least two grooves being sequentially arranged and connected along a direction opposite to the first direction; along a direction opposite to the first direction, the width of an upper groove is greater than the width of a lower groove, and one side surface of the upper groove is flush with one side surface of the lower groove.

[0008] Optionally, the piezoelectric composite stack includes a first electrode layer and at least one second electrode layer, the at least one second electrode layer is arranged above the first electrode layer along the first direction, the first electrode layer is provided with a first gap, the first gap penetrates two opposite surfaces of the first electrode layer in the first direction, the first gap is filled with a first non-metallic layer, and a groove at the same height as the first electrode layer is located in the first non-metallic layer and wrapped by the first non-metallic layer.

[0009] Optionally, a second gap is provided on the second electrode layer, the second gap penetrates two opposite surfaces of the second electrode layer in the first direction, the second gap is filled with a second non-metallic layer, and the groove at the same height as the second electrode layer is located in the second non-metallic layer and wrapped by the second non-metallic layer.

[0010] According to a second aspect of the embodiments of the present application, there is provided a cantilever microphone, comprising: a base layer having a cavity, and a piezoelectric structure as described above stacked on the cavity of the base layer, wherein a groove group of the piezoelectric structure corresponds to the position of the cavity.

[0011] According to a third aspect of an embodiment of the present application, a method for preparing a piezoelectric structure is provided, comprising: providing a substrate layer, and forming a piezoelectric composite stack on the substrate layer, wherein the piezoelectric composite stack comprises a plurality of film layers, and the plurality of film layers are stacked on the substrate layer along a first direction; forming at least one group of groove groups on a surface of the piezoelectric composite stack away from the substrate layer, wherein the groove group passes through two surfaces of the piezoelectric composite stack opposite to each other in the first direction to divide the piezoelectric composite stack into at least two cantilever beams, and the groove group comprises at least two grooves, and the at least two grooves are arranged in a direction opposite to the first direction and are connected in sequence, and along the direction opposite to the first direction, the width of an upper groove is greater than the width of a next groove, and one side of the upper groove is flush with one side of the next groove.

[0012] Optionally, forming at least one group of grooves on the surface of the piezoelectric composite stack facing away from the substrate layer includes: forming a mask layer at least twice on the surface of the piezoelectric composite stack facing away from the substrate layer, wherein before forming the mask layer for the next time, the mask layer formed last time needs to be removed, and the etching slits on the mask layer formed next time are offset by a preset distance relative to the etching slits on the mask layer formed last time along the width direction of the etching slits on the mask layer formed last time, and the preset distance is smaller than the width of the etching slits on the mask layer formed last time; after each mask layer is formed, the membrane layer is etched through the etching slits on the mask layer to form grooves.

[0013] Optionally, a substrate layer is provided, and a piezoelectric composite stack is formed on the substrate layer, wherein the piezoelectric composite stack includes a plurality of film layers, and the plurality of film layers are stacked on the substrate layer along a first direction, including: providing a substrate layer, and forming at least two electrode layers and at least one piezoelectric layer on the substrate layer along a first direction, wherein at least one piezoelectric layer is provided between two adjacent electrode layers; etching the film layer through the etching slits on the mask layer includes: etching the electrode layer through the etching slits on the mask layer, or etching the piezoelectric layer through the etching slits on the mask layer, or etching the electrode layer and the piezoelectric layer simultaneously through the etching slits on the mask layer.

[0014] Optionally, forming at least one group of groove groups on the surface of the piezoelectric composite stack facing away from the substrate layer includes: forming a first mask layer on the surface of the piezoelectric composite stack facing away from the substrate layer, wherein the surface of the first mask layer has a first etching slit of a preset width; etching the membrane layer for a first time through the first etching slit; removing the first mask layer, and forming a second mask layer on the surface of the piezoelectric composite stack facing away from the substrate layer, wherein the surface of the second mask layer has a second etching slit of a preset width, and the second etching slit is offset by a preset distance relative to the first etching slit along the width direction of the groove, and the preset distance is less than the preset width; etching the membrane layer for a second time through the second etching slit.

[0015] Optionally, a substrate layer is provided, and a piezoelectric composite stack is formed on the substrate layer, wherein the piezoelectric composite stack includes a plurality of film layers, and the plurality of film layers are stacked on the substrate layer along a first direction, including: providing a substrate layer, and forming a first electrode layer on the substrate layer, wherein a first gap is provided on the first electrode layer, and the first gap penetrates two surfaces of the first electrode layer opposite to each other in the first direction; piezoelectric layers and second electrode layers are alternately formed on the first electrode layer along the first direction, and the piezoelectric layer closest to the first electrode layer covers the first electrode layer and fills the first gap; at least one group of groove groups is formed on the surface of the piezoelectric composite stack facing away from the substrate layer, including: at least one group of groove groups is formed on the surface of the piezoelectric composite stack facing away from the substrate layer, wherein the orthographic projection of the grooves in the groove group at the same height as the first electrode layer on the substrate layer is located within the contour of the orthographic projection of the first gap on the substrate layer.

[0016] Optionally, a second gap is provided on the second electrode layer, and the second gap runs through two opposite surfaces of the second electrode layer in the first direction, and the piezoelectric layer above the second electrode layer fills the second gap, and the orthographic projection of the grooves in the groove group at the same height as the second electrode layer on the substrate layer is located within the outline of the orthographic projection of the second gap on the substrate layer.

[0017] The beneficial effects of this application include:

[0018] The present application provides a piezoelectric structure, including: a piezoelectric composite stack, the piezoelectric composite stack includes a plurality of film layers, the plurality of film layers are stacked along a first direction, at least one group of grooves is provided on the surface of the piezoelectric composite stack, the groove group penetrates two surfaces of the piezoelectric composite stack opposite to each other in the first direction, so as to divide the piezoelectric composite stack into at least two cantilever beams; the groove group includes at least two grooves, the at least two grooves are sequentially arranged and connected along a direction opposite to the first direction; along the direction opposite to the first direction, the width of the upper groove is greater than the width of the next groove, and one side of the upper groove is flush with one side of the next groove. The piezoelectric structure forms a gap with a width smaller than the width of the groove in the piezoelectric composite stack by arranging a stepped groove group in the piezoelectric composite stack, and limiting the width of the upper groove to be greater than the width of the next groove, and one side of the upper groove is flush with one side of the next groove. In actual processing, it is not necessary to require the width of a single groove to be as small as possible, and it is only necessary to offset the position of the groove each time processing, and process the groove at least twice, so that it is relatively easy to obtain a gap with as small a width as possible. The smaller the gap width, the wider the low-frequency response of the cantilever microphone. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the structure of a cantilever beam microphone provided in an embodiment of the present application;

[0021] Figure 2 This is a comparison chart of the frequency responses of existing cantilever beam microphones at different slot widths;

[0022] Figure 3 One of the structural schematic diagrams of the piezoelectric structure provided in the embodiment of the present application;

[0023] Figure 4 The second structural schematic diagram of the piezoelectric structure provided in the embodiment of the present application;

[0024] Figure 5 The third structural schematic diagram of the piezoelectric structure provided in the embodiment of the present application;

[0025] Figure 6 is a schematic diagram of the structure of an existing piezoelectric structure;

[0026] Figure 7 The fourth structural schematic diagram of the piezoelectric structure provided in the embodiment of the present application;

[0027] Figure 8 for Figure 7 The piezoelectric structure and Figure 6 Frequency response comparison of piezoelectric structures in ;

[0028] Fig. 9 The fifth structural schematic diagram of the piezoelectric structure provided in the embodiment of the present application;

[0029] Fig.10 for Fig. 9 The piezoelectric structure and Figure 6 Frequency response comparison of piezoelectric structures in ;

[0030] Fig.11 One of the preparation flow charts of the piezoelectric structure provided in the embodiment of the present application;

[0031] Fig.12 The second flowchart of the preparation of the piezoelectric structure provided in the embodiment of the present application;

[0032] Fig.13 One of the schematic diagrams of the preparation process of the piezoelectric structure provided in the embodiment of the present application;

[0033] Fig.14 The third flowchart of the preparation of the piezoelectric structure provided in the embodiment of the present application;

[0034] Fig.15 The second schematic diagram of the preparation process of the piezoelectric structure provided in the embodiment of the present application;

[0035] Fig.16 The fourth flowchart of the preparation of the piezoelectric structure provided in the embodiment of the present application;

[0036] Fig.17 This is the fifth flow chart of the preparation of the piezoelectric structure provided in the embodiment of the present application.

[0037] Icons: 10-cantilever microphone; 20-piezoelectric structure; 21-piezoelectric composite stack; 22-membrane layer; 221-first electrode layer; 222-second electrode layer; 223-piezoelectric layer; 224-first gap; 225-first non-metallic layer; 226-second gap; 227-second non-metallic layer; 23-groove; 24-gap; 25-preset plane; 30-base layer; 31-cavity; 40-mask layer; 41-first mask layer; 42-second mask layer; 50-etching gap; 51-first etching gap; 52-second etching gap; 60-cantilever beam; D1-width of the gap; D2-width of the groove; F1-first direction; F2-width direction of the groove; M1-first surface; M2-second surface. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0039] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. It should be noted that, in the absence of conflict, the various features in the embodiments of the present application can be combined with each other, and the combined embodiments are still within the scope of protection of the present application.

[0040] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0041] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0042] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0043] like Figure 1As described above, the slot design between the cantilever beams 60 on the cantilever microphone 10 has a great influence on its low-frequency response capability. Among them, the slot width (i.e., the slot width D1) is a parameter that directly affects the low-frequency response of the cantilever microphone 10. The smaller the slot width, the lower the low-frequency response of the cantilever microphone 10 and the wider the response range. A smaller slot width can help the cantilever microphone 10 capture and reproduce low-frequency sounds more accurately, and by obtaining a wider frequency response, the cantilever microphone 10 system can sense more natural and clear sounds.

[0044] Figure 2 The frequency response comparison diagram of the cantilever microphone 10 at different slot widths shows that, at the same frequency, the smaller the slot width of the cantilever microphone 10, the smaller the signal attenuation; taking the response at 100Hz as an example, the cantilever microphone 10 with a slot width of 1μm has the highest response signal, while the cantilever microphone 10 with a slot width of 2μm has a response attenuation of more than an order of magnitude compared to the former, that is, doubling the slot width will cause more than ten times the attenuation of the response signal of the cantilever microphone 10. Therefore, in order to enable the cantilever microphone 10 to obtain a wider low-frequency response range, the slot width between the cantilever beams 60 should be as small as possible.

[0045] However, in the actual processing of the cantilever microphone 10, it is extremely difficult to obtain the smallest possible slit width because the slit 24 to be processed has a large aspect ratio and contains piezoelectric materials that are difficult to etch.

[0046] To solve the above technical problems, the first aspect of the embodiment of the present application is as follows: Figure 3 and Figure 4 , a piezoelectric structure 20 is provided, comprising: a piezoelectric composite stack 21, the piezoelectric composite stack 21 comprising a plurality of film layers 22, the plurality of film layers 22 being stacked along a first direction F1. Generally, the piezoelectric composite stack 21 comprises at least two electrode layers and at least one piezoelectric layer 223, and at least one piezoelectric layer 223 is disposed between two adjacent electrode layers.

[0047] At least one groove group is provided on the surface of the piezoelectric composite laminate 21, and the groove group penetrates two surfaces of the piezoelectric composite laminate 21 opposite to each other in the first direction F1, so as to divide the piezoelectric composite laminate 21 into at least two cantilever beams 60. It should be noted that when the number of the groove group is one, one groove group divides the piezoelectric composite laminate 21 into two cantilever beams 60; when the number of the groove group is two or more, two or more groove groups cooperate with each other to divide the piezoelectric composite laminate 21 into two or more cantilever beams 60 together.

[0048] Each groove group includes at least two grooves 23, and the at least two grooves 23 are arranged in sequence and connected in the direction opposite to the first direction F1. That is to say, in the direction opposite to the first direction F1, the groove bottom of the previous groove 23 and the groove opening of the next groove 23 are located in the same plane and have an overlapping area, thereby realizing the connection between the two adjacent grooves 23. The grooves 23 are connected in pairs, thereby realizing the connection of all the grooves 23.

[0049] In the direction opposite to the first direction F1, the notch of the uppermost groove 23 is located in the same plane as the first surface M1 of the piezoelectric composite stack 21, and the lowermost groove 23 is a through groove, the bottom of which extends to the second surface M2 of the piezoelectric composite stack 21 opposite to the first surface M1, so that the groove group passes through the two opposite surfaces of the piezoelectric composite stack 21 in the first direction F1.

[0050] Along the direction opposite to the first direction F1, the width D2 of the previous groove is greater than the width D2 of the next groove, and one side of the previous groove 23 is flush with one side of the next groove 23). In this way, after at least two grooves 23 are processed, at least two grooves 23 will jointly form a gap 24 ( Figure 3 The gap 24 extends along the first direction F1 and penetrates two opposite surfaces of the piezoelectric composite laminate 21 in the first direction F1.

[0051] It should be noted that, in this embodiment, there is no limitation on the type, quantity, thickness, material and combination of the film layers 22 in the piezoelectric composite stack 21 , as long as the piezoelectric composite stack 21 can be formed.

[0052] One groove 23 may correspond to only one film layer 22, that is, the groove 23 is only located in one film layer 22. Figure 3 The groove 23 may penetrate two opposite surfaces of the film layer 22 in the first direction F1, or may not penetrate two opposite surfaces of the film layer 22 in the first direction F1. One groove 23 may also correspond to at least two film layers 22, that is, the groove 23 is located in at least two film layers 22 at the same time, such as Figure 3 In one film layer 22, at least two grooves 23 may correspond, that is, at least two grooves 23 are arranged in one film layer 22 at the same time, such as Figure 4 As shown in the film layer 22 located in the middle.

[0053] Along the direction opposite to the first direction F1, the three connected grooves 23 are respectively defined as an upper groove 23, a middle groove 23 and a lower groove 23. In one embodiment, as shown in FIG. Figure 4As shown, the right side of the middle groove 23 is flush with the right side of the upper groove 23 and the right side of the lower groove 23; in another embodiment, as shown Figure 5 As shown, the right side of the middle groove 23 is flush with the right side of the upper groove 23 , and the left side of the middle groove 23 is flush with the left side of the lower groove 23 .

[0054] The piezoelectric structure 20 is provided with a stepped groove group in the piezoelectric composite laminate 21, and the width D2 of the upper groove is defined to be greater than the width D2 of the next groove, and one side of the upper groove 23 is flush with one side of the next groove 23, thereby forming a gap 24 with a width smaller than the width of the groove 23 in the piezoelectric composite laminate 21. In actual processing, it is not necessary to require the width D2 of a single groove to be as small as possible. It is only necessary to offset the position of the groove 23 during each processing and process the groove 23 at least twice. Therefore, it is relatively easy to obtain a gap 24 with the smallest possible width. The smaller the width of the gap 24, the wider the low-frequency response of the cantilever microphone.

[0055] Optionally, see Figure 3 and Figure 4 The piezoelectric composite stack 21 includes a first electrode layer 221 and at least one second electrode layer 222, and the at least one second electrode layer 222 is disposed above the first electrode layer 221 along the first direction F1. Generally speaking, at least one piezoelectric layer 223 is disposed between the first electrode layer 221 and the second electrode layer 222. If the number of the second electrode layers 222 is at least two, at least one piezoelectric layer 223 is also disposed between two adjacent second electrode layers 222.

[0056] The first electrode layer 221 is provided with a first slit 224, and the first slit 224 penetrates two surfaces of the first electrode layer 221 that are opposite to each other in the first direction F1. The first non-metal layer 225 is filled in the first slit 224. The groove 23 at the same height as the first electrode layer 221 in the first direction F1 is located in the first non-metal layer 225 and is wrapped by the first non-metal layer 225. In this way, when the groove 23 at the same height as the first electrode layer 221 is processed by etching gas, the etching gas will not directly react with the first electrode layer 221 to generate metal polymers, thereby effectively reducing the probability of slowing down the etching rate and the failure of the slit.

[0057] Optionally, a second slit 226 is provided on the second electrode layer 222, and the second slit 226 penetrates two surfaces of the second electrode layer 222 that are opposite in the first direction F1. The second non-metallic layer 227 is filled in the second slit 226. The groove 23 at the same height as the second electrode layer 222 in the first direction F1 is located in the second non-metallic layer 227 and is wrapped by the second non-metallic layer 227. In this way, when the groove 23 at the same height as the second electrode layer 222 is processed by etching gas, the etching gas will not directly react with the second electrode layer 222 to generate a metal polymer, thereby further reducing the probability of slowing down the etching rate and the failure of the slit.

[0058] It should be noted that the first non-metallic layer 225 may be a part of the film layer 22 bonded to the first electrode layer 221. When the non-metallic material is used to lay the film layer 22, the non-metallic material is filled into the first gap 224, thereby simultaneously forming the film layer 22 bonded to the first electrode layer 221 and the first non-metallic layer 225. Similarly, the second non-metallic layer 227 may also be a part of the film layer 22 bonded to the second electrode layer 222. When the non-metallic material is used to lay the film layer 22, the non-metallic material is filled into the second gap 226, thereby simultaneously forming the film layer 22 bonded to the second electrode layer 222 and the second non-metallic layer 227.

[0059] Please refer to Figures 6 to 8 , Figure 6 The piezoelectric structure 20 is slit at one time, and only one groove 23 is processed; Figure 7 The piezoelectric structure in the apparatus is slit more than 20 times, and three grooves 23 are processed; Figure 8 for Figure 7 The piezoelectric structure 20 and Figure 6 The frequency response comparison diagram of the piezoelectric structure 20 in FIG. Figure 8 In the figure, curve b represents Figure 7 The piezoelectric structure 20 in FIG. 1 , curve a represents Figure 6 The piezoelectric structure 20 in Figure 8 It can be seen that Figure 7 The piezoelectric structure 20 in FIG. Figure 6 The piezoelectric structure 20 has a smaller signal attenuation at low frequencies, and a smaller response limit at low frequencies, so the corresponding cantilever microphone can have a wider low-frequency response.

[0060] Please refer to Figure 6 , Fig. 9 and Fig.10 , Fig. 9 The piezoelectric structure in the apparatus is slotted more than 20 times, and four grooves 23 are processed; Fig.10 for Fig. 9 The piezoelectric structure 20 and Figure 6 The frequency response comparison diagram of the piezoelectric structure 20 in FIG. Fig.10In the figure, curve e represents Fig. 9 The piezoelectric structure 20 in FIG. 1 , curve a represents Figure 6 The piezoelectric structure 20 in Fig.10 It can be seen that Fig. 9 The piezoelectric structure 20 in FIG. Figure 6 The piezoelectric structure 20 has a smaller signal attenuation at low frequencies, and a smaller response limit at low frequencies, so the corresponding cantilever microphone can have a wider low-frequency response.

[0061] In a second aspect of this embodiment, a cantilever microphone 10 is provided. Figure 1 and Figure 3 , a base layer 30 having a cavity 31 , and a piezoelectric structure 20 as described above stacked on the cavity 31 of the base layer 30 , wherein the groove group of the piezoelectric structure 20 corresponds to the position of the cavity 31 .

[0062] It can be understood that the gap 24 formed by the piezoelectric structure 20 is located above the cavity 31 and communicates with the cavity 31 .

[0063] The cantilever microphone 10 includes the same structure and benefits as the piezoelectric structure 20 in the aforementioned embodiment. The structure and benefits of the piezoelectric structure 20 have been described in detail in the aforementioned embodiment and will not be repeated here.

[0064] For the third aspect of this embodiment, please refer to Fig.11 , a method for preparing a piezoelectric structure 20 is provided, comprising:

[0065] S100: providing a substrate layer, and forming a piezoelectric composite stack on the substrate layer, wherein the piezoelectric composite stack includes a plurality of film layers, and the plurality of film layers are stacked on the substrate layer along a first direction.

[0066] Please refer to Figure 3 The substrate layer is used as a support layer for forming a piezoelectric composite laminate 21 thereon. The multilayer film layers 22 in the piezoelectric composite laminate 21 are stacked along a first direction F1. Preferably, the first direction F1 is perpendicular to the substrate layer. The substrate layer may be part of the piezoelectric structure 20 or may be other structures.

[0067] S200: At least one group of groove groups is formed on the surface of the piezoelectric composite stack facing away from the substrate layer, wherein the groove group penetrates two surfaces of the piezoelectric composite stack that are opposite to each other in a first direction to divide the piezoelectric composite stack into at least two cantilever beams, and the groove group includes at least two grooves, and the at least two grooves are arranged in a direction opposite to the first direction and are connected in sequence, and along the direction opposite to the first direction, the width of the upper groove is greater than the width of the next groove, and one side of the upper groove is flush with one side of the next groove.

[0068] Starting from the surface of the topmost film layer 22 (i.e. the film layer 22 farthest from the substrate layer), at least one group of grooves is processed toward the inside of the piezoelectric composite laminate 21 in the direction opposite to the first direction F1, and each groove group includes at least two grooves 23. A single groove 23 can be obtained by one processing, or by two or more processing. After the processing is completed, the groove group penetrates the bottommost film layer 22 (i.e. the film layer 22 closest to the substrate layer), the width D2 of the previous groove is greater than the width D2 of the next groove, and one side of the previous groove 23 is flush with one side of the next groove 23. In this way, a gap 24 penetrating the two opposite surfaces of the piezoelectric composite laminate 21 in the first direction F1 can be obtained in the piezoelectric composite laminate 21, and the width D1 of the gap is less than the width D2 of the groove.

[0069] By adopting the method for preparing the piezoelectric structure 20, a stepped groove group can be formed in the piezoelectric composite laminate 21, and the width D2 of the previous groove in the groove group is greater than the width D2 of the next groove, and one side of the previous groove 23 and one side of the next groove 23 are located in the same preset plane 25. A gap 24 is formed in the groove group, and the width D1 of the gap is less than the width D2 of any groove in the groove group. Therefore, by adopting the method for preparing the piezoelectric structure 20, a gap 24 with as small a width as possible can be obtained relatively easily.

[0070] Optionally, see Fig.12 , forming at least one group of grooves on the surface of the piezoelectric composite stack facing away from the substrate layer comprises:

[0071] S210: forming a mask layer at least twice on the surface of the piezoelectric composite stack facing away from the substrate layer, wherein before forming the mask layer for the next time, the mask layer formed last time needs to be removed, and the etching slit on the mask layer formed next time is offset by a preset distance relative to the etching slit on the mask layer formed last time along the width direction of the etching slit on the mask layer formed last time, and the preset distance is smaller than the width of the etching slit on the mask layer formed last time.

[0072] S220: After each mask layer is formed, the film layer is etched through the etching gap on the mask layer to form a groove.

[0073] Please refer to Fig.13 The above process is a cyclic process, which requires forming a mask layer 40 on the surface of the piezoelectric composite laminate 21 and etching the piezoelectric composite laminate 21 twice or more. After one etching is completed, the mask layer 40 needs to be removed, and then a new mask layer 40 is formed on the surface of the piezoelectric composite laminate 21, and the piezoelectric composite laminate 21 is etched again. Repeat the above process until the piezoelectric composite laminate 21 is penetrated by the groove group obtained by etching.

[0074] During the etching process, the positions of the etching slits 50 on different mask layers 40 are different. The etching slits 50 on the next mask layer 40 will be offset by a preset distance along the width direction F2 of the groove relative to the etching slits 50 on the previous mask layer 40. The preset distance can be determined according to the total number of etchings and the required slit width D1. It can be understood that the preset distance needs to be smaller than the width of the etching slits 50 on the mask layer 40 formed last time to ensure that the groove 23 obtained by the next etching can be connected with the groove 23 obtained by the last etching. The width direction of the etching slit 50 is also the width direction of the groove 23. The offset preset distance can be achieved by means of overlay error or manually, so that the two photolithography processes have a certain position deviation to obtain a smaller slit width.

[0075] Optionally, the width of the etching gap 50 on the mask layer 40 formed next is equal to the width of the etching gap 50 on the mask layer 40 formed last.

[0076] The width of the etching slits 50 on different mask layers 40 remains unchanged, which can further simplify the slit process and make the slit width D1 as small as possible. During the etching operation, the width of the etching slit 50 can be used as the minimum processing size of the photolithography machine, and the piezoelectric composite stack 21 can be processed and removed at least twice.

[0077] Optionally, see Fig.14 , forming at least one group of grooves on the surface of the piezoelectric composite stack facing away from the substrate layer comprises:

[0078] S211: forming a first mask layer on a surface of the piezoelectric composite stack facing away from the substrate layer, wherein the surface of the first mask layer has a first etching gap of a preset width.

[0079] S221: performing a first etching on the film layer through a first etching gap.

[0080] S212: removing the first mask layer, and forming a second mask layer on the surface of the piezoelectric composite stack facing away from the substrate layer, wherein the surface of the second mask layer has a second etching gap of a preset width, and the second etching gap is offset by a preset distance relative to the first etching gap along the width direction of the groove, and the preset distance is smaller than the preset width.

[0081] S222: etching the film layer for a second time through the second etching gap.

[0082] Please refer to Fig.13During the first etching, a first mask layer 41 having a first etching slit 51 is first formed on the surface of the uppermost film layer 22, and then the film layer 22 is etched using the first etching slit 51. After the first etching is completed, the first mask layer 41 needs to be removed. During the second etching, a second mask layer 42 having a second etching slit 52 is also first formed on the surface of the uppermost film layer 22, and then the film layer 22 is etched using the second etching slit 52. Thus, a groove group having two grooves 23 can be obtained, and the width D1 of the slit formed in the groove group is smaller than the width D2 of the groove.

[0083] It can be understood that if etching needs to be continued to form the groove 23, the second mask layer 42 can be removed, and the third etching, the fourth etching, ..., can be continued. The etching process is the same as the first etching and the second etching process.

[0084] Please refer to Fig.15 , Fig.15 The process of three etchings is shown, wherein the photolithography position is shifted to the right during the second etching, and the photolithography position is shifted to the left during the third etching. When the width of the etching slit 50 remains unchanged, the width D1 of the obtained slit must be smaller than the width of the etching slit 50. It can be understood that similar results can be obtained during the second and third etchings, regardless of whether the photolithography position is shifted to the left or to the right. As the number of etchings increases, the width D1 of the slit becomes smaller and smaller. Fig.15 The groove group formed in the embodiment is an octagon. The method for preparing the piezoelectric structure 20 provided in the embodiment of the present application can also be used to prepare groove groups in the shape of a hexagon, a decagon, a dodecagon, a tetradecagon, etc.

[0085] Optionally, see Fig.16 , providing a substrate layer, and forming a piezoelectric composite stack on the substrate layer, wherein the piezoelectric composite stack includes a plurality of film layers, and the plurality of film layers are stacked on the substrate layer along a first direction and include:

[0086] S110: providing a substrate layer, and forming at least two electrode layers and at least one piezoelectric layer on the substrate layer along a first direction, wherein at least one piezoelectric layer is provided between two adjacent electrode layers.

[0087] Etching the film layer through the etching gap on the mask layer includes:

[0088] S223: etching the electrode layer through the etching slits on the mask layer, or etching the piezoelectric layer through the etching slits on the mask layer, or etching the electrode layer and the piezoelectric layer simultaneously through the etching slits on the mask layer.

[0089] Please refer to Fig.13 and Fig.15When etching the piezoelectric layer 223, the etching gas will pass through the electrode layer above the piezoelectric layer 223. At this time, the selectivity of the etching process can be used to select whether to etch the electrode layer. Fig.13 As shown, if the electrode layer is not etched, the electrode layer becomes a hard mask when etching the piezoelectric layer 223; Fig.15 As shown, if the electrode layer is selected to be etched, the electrode layer above the piezoelectric layer 223 will also be partially removed when the piezoelectric layer 223 is etched. However, due to the different etching rates of the electrode layer and the piezoelectric layer 223, when the etching time is the same, the etching depth of the piezoelectric layer 223 covered by the electrode layer is less than the etching depth of the piezoelectric layer 223 not covered by the electrode layer.

[0090] Optionally, see Fig.17 , providing a substrate layer, and forming a piezoelectric composite stack on the substrate layer, wherein the piezoelectric composite stack includes a plurality of film layers, and the plurality of film layers are stacked on the substrate layer along a first direction and include:

[0091] S120: providing a substrate layer, and forming a first electrode layer on the substrate layer, wherein a first slit is provided on the first electrode layer, and the first slit penetrates two opposite surfaces of the first electrode layer in a first direction.

[0092] S130: alternately forming piezoelectric layers and second electrode layers on the first electrode layer along a first direction, wherein the piezoelectric layer closest to the first electrode layer covers the first electrode layer and fills the first gap.

[0093] Forming at least one group of grooves on a surface of the piezoelectric composite stack facing away from the substrate layer comprises:

[0094] S230: forming at least one group of grooves on the surface of the piezoelectric composite stack facing away from the substrate layer, wherein the orthographic projection of the grooves in the groove group at the same height as the first electrode layer on the substrate layer is located within the contour of the orthographic projection of the first gap on the substrate layer.

[0095] Please refer to Figure 5 , a first slit 224 is provided on the first electrode layer 221, and a piezoelectric material is used to fill the first slit 224. When the groove 23 at the same height as the first electrode layer 221 is processed by etching gas, the etching gas will not directly react with the first electrode layer 221 to generate a metal polymer, thereby effectively reducing the probability of slowing down the etching rate and the failure of the slit.

[0096] Furthermore, a second slit 226 is provided on the second electrode layer 222, and the second slit 226 penetrates two opposite surfaces of the second electrode layer 222 in the first direction F1. The piezoelectric layer 223 above the second electrode layer 222 fills the second slit 226, and the orthographic projection of the groove 23 in the groove group at the same height as the second electrode layer 222 on the substrate layer is located within the outline of the orthographic projection of the second slit 226 on the substrate layer.

[0097] Thus, when etching gas is used to process the groove 23 at the same height as the second electrode layer 222, the etching gas will not directly react with the second electrode layer 222 to generate metal polymer, thereby further reducing the probability of etching rate slowdown and seam opening failure.

[0098] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A piezoelectric structure, characterized in that: include: A piezoelectric composite laminate, the piezoelectric composite laminate comprising a plurality of film layers, the plurality of film layers being stacked along a first direction, the surface of the piezoelectric composite laminate being provided with at least one group of grooves, the grooves penetrating two surfaces of the piezoelectric composite laminate opposite to each other in the first direction, so as to divide the piezoelectric composite laminate into at least two cantilever beams; The groove group includes at least two grooves, and at least two of the grooves are arranged in sequence and connected along a direction opposite to the first direction; along the direction opposite to the first direction, the width of the previous groove is greater than the width of the next groove, and one side of the previous groove is flush with one side of the next groove.

2. The piezoelectric structure according to claim 1, characterized in that The piezoelectric composite stack includes a first electrode layer and at least one second electrode layer, the at least one second electrode layer is arranged above the first electrode layer along the first direction, the first electrode layer is provided with a first gap, the first gap penetrates two opposite surfaces of the first electrode layer in the first direction, the first gap is filled with a first non-metallic layer, and the groove at the same height as the first electrode layer is located in the first non-metallic layer and is wrapped by the first non-metallic layer.

3. The piezoelectric structure according to claim 2, characterized in that: A second gap is provided on the second electrode layer, and the second gap runs through two opposite surfaces of the second electrode layer in the first direction. The second gap is filled with a second non-metallic layer, and the groove at the same height as the second electrode layer is located in the second non-metallic layer and wrapped by the second non-metallic layer.

4. A cantilever microphone, characterized in that: include: A base layer having a cavity, and a piezoelectric structure according to any one of claims 1 to 3 stacked on the cavity of the base layer, wherein the groove group of the piezoelectric structure corresponds to the position of the cavity.

5. A method for preparing a piezoelectric structure, characterized in that: include: Providing a substrate layer, and forming a piezoelectric composite stack on the substrate layer, wherein the piezoelectric composite stack includes a plurality of film layers, and the plurality of film layers are stacked on the substrate layer along a first direction; At least one group of grooves is formed on the surface of the piezoelectric composite stack facing away from the substrate layer, wherein the grooves penetrate two surfaces of the piezoelectric composite stack that are opposite to each other in the first direction to divide the piezoelectric composite stack into at least two cantilever beams, and the grooves include at least two grooves, at least two of which are arranged in a direction opposite to the first direction and are connected in sequence, and along the direction opposite to the first direction, the width of the previous groove is greater than the width of the next groove, and one side of the previous groove is flush with one side of the next groove.

6. The method for preparing a piezoelectric structure according to claim 5, characterized in that: The forming of at least one group of grooves on the surface of the piezoelectric composite stack facing away from the substrate layer comprises: A mask layer is formed at least twice on the surface of the piezoelectric composite stack away from the substrate layer, wherein before forming the mask layer for the next time, the mask layer formed for the last time needs to be removed, and the etching slit on the mask layer formed for the next time is offset by a preset distance relative to the etching slit on the mask layer formed for the last time along the width direction of the etching slit on the mask layer formed for the last time, and the preset distance is smaller than the width of the etching slit on the mask layer formed for the last time; After the mask layer is formed each time, the film layer is etched through the etching gap on the mask layer to form a groove.

7. The method for preparing a piezoelectric structure according to claim 6, characterized in that: The step of providing a substrate layer and forming a piezoelectric composite stack on the substrate layer, wherein the piezoelectric composite stack includes a plurality of film layers, and the plurality of film layers are stacked on the substrate layer along a first direction, comprises: Providing a substrate layer, and forming at least two electrode layers and at least one piezoelectric layer on the substrate layer along a first direction, wherein at least one piezoelectric layer is provided between two adjacent electrode layers; The etching of the film layer through the etching gap on the mask layer comprises: The electrode layer is etched through the etching slits on the mask layer, or the piezoelectric layer is etched through the etching slits on the mask layer, or the electrode layer and the piezoelectric layer are etched simultaneously through the etching slits on the mask layer.

8. The method for preparing a piezoelectric structure according to claim 6, characterized in that: The forming of at least one group of grooves on the surface of the piezoelectric composite stack facing away from the substrate layer comprises: Forming a first mask layer on a surface of the piezoelectric composite stack facing away from the substrate layer, wherein the surface of the first mask layer has a first etching gap of a preset width; Performing a first etching on the film layer through the first etching slit; Removing the first mask layer, and forming a second mask layer on the surface of the piezoelectric composite stack away from the substrate layer, wherein the surface of the second mask layer has a second etching slit of the preset width, and the second etching slit is offset by a preset distance relative to the first etching slit along the width direction of the groove, and the preset distance is smaller than the preset width; The film layer is etched a second time through the second etching gap.

9. The method for preparing a piezoelectric structure according to claim 5, characterized in that: The step of providing a substrate layer and forming a piezoelectric composite stack on the substrate layer, wherein the piezoelectric composite stack includes a plurality of film layers, and the plurality of film layers are stacked on the substrate layer along a first direction, comprises: Providing a substrate layer, and forming a first electrode layer on the substrate layer, wherein a first slit is provided on the first electrode layer, and the first slit penetrates two surfaces of the first electrode layer that are opposite to each other in the first direction; Alternatingly forming a piezoelectric layer and a second electrode layer on the first electrode layer along a first direction, wherein the piezoelectric layer closest to the first electrode layer covers the first electrode layer and fills the first gap; The forming of at least one group of grooves on the surface of the piezoelectric composite stack facing away from the substrate layer comprises: At least one group of grooves is formed on the surface of the piezoelectric composite stack facing away from the substrate layer, wherein the orthographic projection of the grooves in the groove group at the same height as the first electrode layer on the substrate layer is located within the contour of the orthographic projection of the first gap on the substrate layer.

10. The method for preparing a piezoelectric structure according to claim 9, characterized in that: A second gap is provided on the second electrode layer, and the second gap runs through two opposite surfaces of the second electrode layer in the first direction. The piezoelectric layer above the second electrode layer fills the second gap, and the orthographic projection of the grooves in the groove group at the same height as the second electrode layer on the substrate layer is located within the outline of the orthographic projection of the second gap on the substrate layer.

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