Piezoelectric structure, piezoelectric MEMS microphone and preparation method of piezoelectric structure

Abstract

The invention provides a piezoelectric structure, a piezoelectric MEMS microphone and a preparation method of the piezoelectric structure, and relates to the technical field of semiconductors. The piezoelectric structure comprises a first electrode layer and at least one composite film layer arranged on the first electrode layer in the first direction, each composite film layer comprises a piezoelectric layer and a second electrode layer arranged on the side, away from the first electrode layer, of the piezoelectric layer, and a narrow gap is formed in the surface of the second electrode layer farthest from the first electrode layer; the narrow gap penetrates through two opposite surfaces of the piezoelectric structure in the first direction so as to divide the piezoelectric structure into at least two cantilever beams; the first electrode layer is provided with a first gap, the narrow gap is located in the first gap, and the outline of the narrow gap does not intersect with the outline of the first gap. According to the piezoelectric structure, the first gap corresponding to the position of the narrow gap is formed in the first electrode layer, and during slotting, etching gas cannot directly react with the first electrode layer to generate a metal polymer, so that the etching rate can be prevented from being slowed down, and the probability of slotting failure is reduced.

Description

Technical Field

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

[0002] As an advanced acoustic sensor technology, piezoelectric MEMS microphones have been rapidly developed due to their many advantages such as low power consumption, fast response, and high reliability. Piezoelectric MEMS microphones are mainly composed of a piezoelectric unit and an ASIC circuit, wherein the piezoelectric unit includes a substrate, a support structure and a piezoelectric structure sequentially arranged on the substrate. The piezoelectric structure includes at least two electrode layers and at least one piezoelectric layer alternately stacked, and a slit is arranged on the piezoelectric structure, which penetrates the piezoelectric structure to form a cantilever beam.

[0003] However, during the slitting process, whenever the etching process reaches the bottom of the piezoelectric film, that is, when the last bottom electrode slitting begins after the etching of the piezoelectric layer is completed, a layer of polymer residue that is difficult to remove will form on the inner wall of the groove that has been etched. As the etching of the bottom electrode continues, the polymer continues to grow, causing the etching rate to slow down, and it is possible that the entire etching path downward will be blocked, hindering the etching process and causing the slitting failure. Summary of the invention

[0004] The purpose of the present application is to provide a piezoelectric structure, a piezoelectric MEMS microphone and a method for preparing a piezoelectric structure in response to the above-mentioned deficiencies in the prior art, which can avoid the etching gas from directly reacting with the bottom electrode to form a metal polymer in the later stage of the slitting process, prevent the etching rate from slowing down, and reduce the probability of slitting failure.

[0005] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows: According to a first aspect of an embodiment of the present application, a piezoelectric structure is provided, comprising: a first electrode layer and at least one group of composite film layers arranged on the first electrode layer along a first direction, the composite film layer comprising a piezoelectric layer and a second electrode layer arranged on a side of the piezoelectric layer away from the first electrode layer, a surface of the second electrode layer farthest from the first electrode layer is provided with a gap, the gap penetrates two surfaces of the piezoelectric structure opposite to each other in the first direction, so as to divide the piezoelectric structure into at least two cantilever beams; a first gap is provided on the first electrode layer, the first gap penetrates two surfaces of the first electrode layer opposite to each other in the first direction, the gap is located within the first gap and the outline of the gap does not intersect with the outline of the first gap.

[0006] Optionally, the first gap is filled with non-metallic material.

[0007] Optionally, the piezoelectric layer closest to the first electrode layer is attached to the first electrode layer and fills the first gap.

[0008] Optionally, at least one of the second electrode layers is provided with a second slit, the second slit runs through two opposite surfaces of the second electrode layer in the first direction, the narrow gap is located in the second slit and the outline of the narrow gap does not intersect with the outline of the second slit.

[0009] Optionally, the second gap is filled with non-metallic material.

[0010] Optionally, along the first direction, the piezoelectric layer of the next composite film layer is attached to the second electrode layer of the previous composite film layer and fills the second gap.

[0011] According to a second aspect of the embodiments of the present application, a piezoelectric MEMS microphone is provided, comprising any one of the piezoelectric structures described above.

[0012] According to a third aspect of an embodiment of the present application, a method for preparing a piezoelectric structure is provided, comprising: providing a supporting film layer, and forming a first electrode layer on the supporting film layer along a first direction, wherein a first gap is provided on the first electrode layer, and the first gap penetrates two surfaces of the first electrode layer that are opposite to each other in the first direction; forming at least one group of composite film layers on the first electrode layer along the first direction, wherein the composite film layer covers the first gap, and the composite film layer comprises a piezoelectric layer and a second electrode layer, and the second electrode layer is located on a side of the piezoelectric layer away from the first electrode layer; etching from the topmost second electrode layer toward the direction of the supporting film layer to form a narrow gap that at least penetrates all the composite film layers and the first electrode layer, thereby dividing all the composite film layers and the first electrode layer into at least two cantilever beams, wherein the narrow gap is located in the first gap and the outline of the narrow gap does not intersect with the outline of the first gap.

[0013] Optionally, the surface of the second electrode layer has a second slit, the second slit penetrates two opposite surfaces of the second electrode layer in the first direction, the narrow gap is also located in the second slit, and the outline of the narrow gap does not intersect with the outline of the second slit.

[0014] Optionally, a supporting film layer is provided, and a first electrode layer is formed on the supporting film layer along a first direction, wherein a first gap is provided on the first electrode layer, comprising: providing a supporting film layer, laying a layer of first electrode material on the supporting film layer, and patterning the first electrode material to form a first electrode layer having a first gap; forming at least one group of composite film layers on the first electrode layer along a first direction comprises: laying a layer of piezoelectric material on the first electrode layer to form a piezoelectric layer, wherein the piezoelectric layer covers a surface of the first electrode layer and fills the first gap of the first electrode layer; or, laying a layer of piezoelectric material on the second electrode layer to form a piezoelectric layer, wherein the piezoelectric layer covers a surface of the second electrode layer and fills a second gap of the second electrode layer; laying a layer of second electrode material on the piezoelectric layer, and patterning the second electrode material to form a second electrode layer having a second gap.

[0015] The beneficial effects of this application include: The present application provides a piezoelectric structure, comprising: a first electrode layer and at least one group of composite film layers arranged on the first electrode layer along a first direction, the composite film layer comprising a piezoelectric layer and a second electrode layer arranged on a side of the piezoelectric layer away from the first electrode layer, a narrow gap is arranged on the surface of the second electrode layer farthest from the first electrode layer, and the narrow gap penetrates two opposite surfaces of the piezoelectric structure in the first direction to divide the piezoelectric structure into at least two cantilever beams; a first slit is arranged on the first electrode layer, the first slit penetrates two opposite surfaces of the first electrode layer in the first direction, and the first slit penetrates two opposite side surfaces of the first electrode layer in the second direction, the narrow gap is located in the first slit and the outline of the narrow gap does not intersect with the outline of the first slit. The above-mentioned piezoelectric structure is provided with a first slit on the first electrode layer, the first slit corresponds to the position of the slit in the first direction, and the cross-sectional size of the first slit is larger than the cross-sectional size of the slit. When the slit is opened to the first electrode layer, the etching gas will not directly react with the metal material of the first electrode layer to generate a metal polymer, so the etching rate can be prevented from slowing down and the probability of slit failure can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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.

[0017] Figure 1 is a schematic diagram of the structure of an existing piezoelectric structure; Figure 2 A schematic diagram of the slit process of an existing piezoelectric structure; Figure 3 One of the structural schematic diagrams of the piezoelectric structure provided in the embodiment of the present application; Figure 4 The second structural schematic diagram of the piezoelectric structure provided in the embodiment of the present application; Figure 5 The third structural schematic diagram of the piezoelectric structure provided in the embodiment of the present application; Figure 6 The fourth structural schematic diagram of the piezoelectric structure provided in the embodiment of the present application; Figure 7 A microscopic cross-sectional view of a piezoelectric structure provided in an embodiment of the present application; Figure 8 A schematic diagram of the structure of a piezoelectric MEMS microphone provided in an embodiment of the present application; Fig. 9 One of the preparation flow charts of the piezoelectric structure provided in the embodiment of the present application; Fig.10 A schematic diagram of the preparation process of the piezoelectric structure provided in the embodiment of the present application; Fig.11 The second flowchart of the preparation of the piezoelectric structure provided in the embodiment of the present application.

[0018] Icons: 10-existing piezoelectric structure; 11-electrode; 12-piezoelectric film; 13-slit; 14-groove; 15-polymer; 20-piezoelectric structure; 21-first electrode layer; 211-first gap; 22-composite film layer; 221-piezoelectric layer; 222-second electrode layer; 2221-second gap; 23-slit; 24-cantilever beam; 30-piezoelectric MEMS microphone; 31-substrate; 311-acoustic hole; 32-MEMS chip; 321-cavity; 33-ASIC circuit; 40-oxide; 50-platinum; A-first direction. DETAILED DESCRIPTION

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] Please refer to Figure 1 The existing piezoelectric structure 10 includes two opposite electrodes 11 and a piezoelectric film 12 disposed between the two electrodes 11. A slit 13 is disposed on the surface of the electrode 11. The slit 13 penetrates the electrode 11 and the piezoelectric film 12 to divide the existing piezoelectric structure 10 into two cantilever beams. Figure 2 During the slitting process, whenever the etching process reaches the bottom of the piezoelectric film 12, that is, when the slitting of the last electrode 11 is started after the etching of the piezoelectric layer 221 is completed, a layer of polymer 15 residue that is difficult to remove will be formed on the inner wall of the groove 14 that has been etched. As the etching of the last electrode 11 continues, the polymer 15 continues to grow, resulting in a slowdown in the etching rate, and it is possible that the downward etching path is completely blocked, blocking the etching process and causing the slitting failure.

[0025] In order to solve the above technical problems, the first aspect of the embodiment of the present application, please refer to Figure 3 and Figure 4 , a piezoelectric structure 20 is provided, comprising: a first electrode layer 21 and at least one group of composite film layers 22 arranged on the first electrode layer 21 along a first direction A, the composite film layer 22 comprising a piezoelectric layer 221 and a second electrode layer 222 arranged on a side of the piezoelectric layer 221 away from the first electrode layer 21, a surface of the second electrode layer 222 farthest from the first electrode layer 21 is provided with a slit 23, the slit 23 penetrates through two opposite surfaces of the piezoelectric structure 20 in the first direction A, so as to divide the piezoelectric structure 20 into at least two cantilever beams 24; a first slit 211 is provided on the first electrode layer 21, the first slit 211 penetrates through two opposite surfaces of the first electrode layer 21 in the first direction A, the slit 23 is located in the first slit 211 and the outline of the slit 23 does not intersect with the outline of the first slit 211.

[0026] It should be noted that the piezoelectric structure 20 has a multi-layer film layer, which includes at least a first electrode layer 21, a piezoelectric layer 221, and a second electrode layer 222, and may also include other film layers. During preparation, the multi-layer film layer is stacked layer by layer on the supporting film layer along a first direction A, wherein the first direction A is preferably perpendicular to the surface of the supporting film layer. After the piezoelectric structure 20 is prepared, the supporting film layer can be removed or retained.

[0027] The number of the first electrode layer 21 is one layer, and the first electrode layer 21 is the electrode layer closest to the supporting film layer. The number of the composite film layers 22 is at least one group, and each group of composite film layers 22 includes a piezoelectric layer 221 and a second electrode layer 222, wherein the piezoelectric layer 221 is closer to the first electrode layer 21 than the second electrode layer 222. The number of the piezoelectric layer 221 and the second electrode layer 222 is not limited. The first electrode layer 21 and the piezoelectric layer 221 of the composite film layer 22, and the piezoelectric layer 221 and the second electrode layer 222 can be directly bonded, or other film layers can be provided.

[0028] The piezoelectric structure 20 is also provided with a slit 23, and the slit 23 penetrates all the film layers of the piezoelectric structure 20 along the first direction A. If the supporting film layer is not removed after the piezoelectric structure 20 is prepared, the slit 23 also needs to penetrate the supporting film layer along the first direction A. The number of slits 23 can be one, two, or more. When the number of slits 23 is one, one slit 23 divides the piezoelectric structure 20 into two cantilever beams 24; when the number of slits 23 is two or more, two or more slits 23 cooperate with each other to jointly divide the piezoelectric structure 20 into two or more cantilever beams 24.

[0029] The first electrode layer 21 is provided with a first slit 211, and the first slit 211 penetrates two opposite surfaces of the first electrode layer 21 in the first direction A. It can be understood that the two opposite surfaces of the first electrode layer 21 in the first direction A face the support film layer and the composite film layer 22 respectively. The number of the first slits 211 can be one, two or more. One first slit 211 can correspond to one narrow gap 23, or two or more narrow gaps 23. The portion of the narrow gap 23 passing through the first slit 211 is located in the first slit 211, and the contour of the portion of the narrow gap 23 passing through the first slit 211 (i.e., the side wall of the narrow gap 23) does not intersect with the contour of the first slit 211 (i.e., the side wall of the first slit 211). In this way, in the process of forming the narrow gap 23, when the etching process proceeds to the beginning of the slit of the first electrode layer 21, the etching gas will not directly react with the metal material of the first electrode layer 21 to generate a metal polymer, thereby preventing the etching rate from slowing down and reducing the probability of slit failure.

[0030] The piezoelectric structure 20 is provided with a first slit 211 on the first electrode layer 21, and the first slit 211 corresponds to the slit 23 in the first direction A, and the cross-sectional dimension of the first slit 211 is larger than the cross-sectional dimension of the slit 23. When the slit is opened to the first electrode layer 21, the etching gas will not directly react with the metal material of the first electrode layer 21 to generate a metal polymer, thereby preventing the etching rate from slowing down and reducing the probability of slit failure.

[0031] Optionally, the first gap 211 is filled with non-metallic material.

[0032] Filling the first slit 211 with a non-metallic material can prevent the film layer covering the first electrode layer 21 from collapsing at the location of the first slit 211. In addition, when the slit is opened to the first electrode layer 21, the non-metallic material will directly contact the etching gas and isolate the etching gas from the first electrode layer 21, thereby completely avoiding the contact between the etching gas and the first electrode layer 21.

[0033] Optionally, the piezoelectric layer 221 closest to the first electrode layer 21 is attached to the first electrode layer 21 and fills the first gap 211 .

[0034] The piezoelectric material used to prepare the piezoelectric layer 221 will not react with the etching gas to generate a metal polymer. The piezoelectric layer 221 in the first group of composite film layers 22 along the first direction A is arranged to be attached to the first electrode layer 21 and fill the first gap 211, which can simplify the preparation process of the piezoelectric structure 20 and use the piezoelectric material to isolate the etching gas from the first electrode layer 21.

[0035] In the above embodiments, please refer to Figure 5 and Figure 6 There is no limitation on whether the second electrode layer 222 is provided with a slit corresponding to the position of the narrow gap 23. The second electrode layer 222 may be provided with a slit like the first electrode layer 21, or may not be provided with a slit. When there are two or more second electrode layers 222, all the second electrode layers 222 may be provided with a slit, or none of the second electrode layers 222 may be provided with a slit, or some of the second electrode layers 222 may be provided with a slit, and some of the second electrode layers 222 may not be provided with a slit.

[0036] Optionally, at least one of the second electrode layers 222 is provided with a second slit 2221 , which penetrates two opposite surfaces of the second electrode layer 222 in the first direction A, and the slit 23 is located in the second slit 2221 and the outline of the slit 23 does not intersect with the outline of the second slit 2221 .

[0037] When the number of the second electrode layer 222 is one layer, the second electrode layer 222 is provided with a second slit 2221; when the number of the second electrode layer 222 is two or more layers, at least one of the second electrode layers 222 is provided with a second slit 2221. The second slit 2221 runs through two surfaces of the second electrode layer 222 that are opposite to each other in the first direction A. It can be understood that the two surfaces of the second electrode layer 222 that are opposite to each other in the first direction A are respectively the surface facing the supporting film layer and the surface away from the supporting film layer. The number of the second slits 2221 on one second electrode layer 222 can be one, two or more. One second slit 2221 can correspond to one narrow gap 23, or two or more narrow gaps 23. The size of the second slit 2221 can be the same as the size of the first slit 211, or it can be different from the size of the first slit 211.

[0038] The area on the slit 23 corresponding to the second electrode layer 222 is located in the second slit 2221 and the outline of the slit 23 does not intersect with the outline of the second slit 2221. In this way, during the slit opening process, when the etching process begins to open the second electrode layer 222 where the second slit 2221 is located, the etching gas will not directly react with the metal material of the second electrode layer 222 to generate a metal polymer. The second slit 2221 cooperates with the first slit 211 to further prevent the etching rate from slowing down and reduce the probability of slit opening failure. Preferably, all second electrode layers 222 are provided with second slits 2221.

[0039] Optionally, the second gap 2221 is filled with non-metallic material.

[0040] Filling the second slit 2221 with a non-metallic material can prevent the film layer covering the second electrode layer 222 from collapsing at the location of the second slit 2221. In addition, when the slit is opened to the second electrode layer 222 where the second slit 2221 is located, the non-metallic material will directly contact the etching gas and isolate the etching gas from the second electrode layer 222, thereby completely avoiding the contact between the etching gas and the second electrode layer 222.

[0041] Optionally, along the first direction A, the piezoelectric layer 221 of the next composite film layer 22 is attached to the second electrode layer 222 of the previous composite film layer 22 and fills the second gap 2221 .

[0042] The piezoelectric material used to prepare the piezoelectric layer 221 will not react with the etching gas to generate a metal polymer. The piezoelectric layer 221 of the next composite film layer 22 along the first direction A is arranged to be attached to the second electrode layer 222 of the previous composite film layer 22 and fill the second gap 2221, which can simplify the preparation process of the piezoelectric structure 20 and use the piezoelectric material to isolate the etching gas from the second electrode layer 222.

[0043] Figure 7 The microscopic cross-sectional view of the piezoelectric structure 20 provided in the embodiment of the present application is shown in FIG. Figure 7 It can be seen that the slit effect of the piezoelectric structure 20 provided in the embodiment of the present application is good, and no metal polymer that is difficult to remove appears on the inner wall of the slit 23. It should be noted that Figure 7 The uppermost second electrode layer 222 is covered with oxide 40, and the material above the oxide 40 and filled in the narrow gap 23 is platinum 50. The purpose of retaining the oxide 40 and platinum 50 is to facilitate the acquisition of the full cross-sectional view of the narrow gap 23 when taking pictures.

[0044] According to a second aspect of the embodiments of the present application, a piezoelectric MEMS microphone 30 is provided, comprising any one of the piezoelectric structures 20 described above.

[0045] The piezoelectric MEMS microphone 30 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.

[0046] Optionally, see Figure 3 and Figure 8 The piezoelectric MEMS microphone 30 includes a substrate 31, a MEMS chip 32 with a cavity 321 arranged on the substrate 31, and an ASIC circuit 33. A piezoelectric structure 20 is provided on the side of the MEMS chip 32 facing away from the substrate 31, and the piezoelectric structure 20 covers the cavity 321. An acoustic hole 311 is provided on the substrate 31. The acoustic hole 311, the cavity 321 and the gap 23 of the piezoelectric structure 20 are connected to each other, and the piezoelectric structure 20 is electrically connected to the ASIC circuit 33.

[0047] In a third aspect of the present application, a method for preparing a piezoelectric structure is provided. Fig. 9 ,include: S100: providing a supporting film layer, and forming a first electrode layer on the supporting film layer along a first direction, 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 the first direction.

[0048] Please refer to Fig.10 When preparing the first electrode layer 21, a first slit 211 is reserved on the first electrode layer 21, and the first slit 211 runs through the surface of the first electrode layer 21 facing the support film layer and the surface away from the support film layer.

[0049] S200: forming at least one group of composite film layers on the first electrode layer along a first direction, wherein the composite film layers cover the first gap, the composite film layers include a piezoelectric layer and a second electrode layer, and the second electrode layer is located on a side of the piezoelectric layer away from the first electrode layer.

[0050] At least one group of composite film layers 22 is formed on the side of the first electrode layer 21 away from the supporting film layer, and the at least one group of composite film layers 22 is stacked in sequence along the first direction A. Each group of composite film layers 22 includes a piezoelectric layer 221 and a second electrode layer 222, wherein the piezoelectric layer 221 is formed first and then the second electrode layer 222 is formed.

[0051] S300: Etching from the top second electrode layer toward the direction of the supporting film layer to form a narrow gap that at least penetrates all the composite film layers and the first electrode layer, thereby dividing all the composite film layers and the first electrode layer into at least two cantilever beams, wherein the narrow gap is located in the first gap and the outline of the narrow gap does not intersect with the outline of the first gap.

[0052] Please refer to Figure 6 The uppermost second electrode layer 222 is the second electrode layer 222 farthest from the supporting film layer, and etching is performed from the side of the second electrode layer 222 away from the supporting film layer toward the direction where the supporting film layer is located, thereby forming a slit 23 that penetrates all film layers. The portion of the slit 23 that passes through the first slit 211 is located within the first slit 211, and the contour of the portion of the slit 23 that passes through the first slit 211 (i.e., the side wall of the slit 23) does not intersect with the contour of the first slit 211 (i.e., the side wall of the first slit 211).

[0053] By adopting the above-mentioned method for preparing the piezoelectric structure, during the process of forming the slit 23, when the slit is opened to the first electrode layer 21, the etching gas will not directly react with the metal material of the first electrode layer 21 to generate a metal polymer, thereby preventing the etching rate from slowing down and reducing the probability of slit failure.

[0054] Optionally, the surface of the second electrode layer 222 has a second slit 2221 , which penetrates two opposite surfaces of the second electrode layer 222 in the first direction A, and the slit 23 is also located in the second slit 2221 and the outline of the slit 23 does not intersect with the outline of the second slit 2221 .

[0055] When preparing the second electrode layer 222, a second slit 2221 is reserved on the second electrode layer 222, and the second slit 2221 penetrates the surface of the second electrode layer 222 facing the support film layer and the surface away from the support film layer. With such a configuration, during the slitting process, when the etching process begins to slit the second electrode layer 222 where the second slit 2221 is located, the etching gas will not directly react with the metal material of the second electrode layer 222 to generate a metal polymer. The second slit 2221 cooperates with the first slit 211 to further prevent the etching rate from slowing down and reduce the probability of slitting failure. Preferably, all second electrode layers 222 are provided with a second slit 2221.

[0056] Optionally, see Fig.11, providing a supporting film layer, and forming a first electrode layer on the supporting film layer, wherein a first gap is provided on the first electrode layer, comprising: S110: providing a supporting film layer, laying a layer of first electrode material on the supporting film layer, and patterning the first electrode material to form a first electrode layer having a first gap.

[0057] Please refer to Fig.10 , a complete layer of first electrode material is laid on the supporting film layer, and then the first electrode material is patterned to remove part of the first electrode material, thereby forming a first electrode layer 21 having a first gap 211 .

[0058] Forming at least one set of composite film layers on the first electrode layer along a first direction comprises: S210: Laying a layer of piezoelectric material on the first electrode layer to form a piezoelectric layer, wherein the piezoelectric layer covers the surface of the first electrode layer and fills the first gap of the first electrode layer; or, laying a layer of piezoelectric material on the second electrode layer to form a piezoelectric layer, wherein the piezoelectric layer covers the surface of the second electrode layer and fills the second gap of the second electrode layer.

[0059] When preparing the composite film layer 22 bonded to the first electrode layer 21 , a complete layer of piezoelectric material is laid on the first electrode layer 21 . When laying the piezoelectric material, the piezoelectric material also fills the first gap 211 on the first electrode layer 21 .

[0060] When preparing the next composite film layer 22 to be bonded to the previous composite film layer 22, a complete layer of piezoelectric material is laid on the second electrode layer 222 of the previous composite film layer 22. When laying the piezoelectric material, if a second gap 2221 is provided on the second electrode layer 222 below, the piezoelectric material will also fill the second gap 2221.

[0061] S220: Laying a layer of second electrode material on the piezoelectric layer, and patterning the second electrode material to form a second electrode layer having a second gap.

[0062] After the piezoelectric layer 221 is prepared, a complete layer of second electrode material is laid on the piezoelectric layer 221 , and then the second electrode material is patterned to remove part of the second electrode material, thereby forming a second electrode layer 222 with a second gap 2221 .

[0063] Steps S210 and S220 are repeated until all composite film layers 22 are prepared.

[0064] 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 first electrode layer and at least one group of composite film layers arranged on the first electrode layer along a first direction, the composite film layer comprising a piezoelectric layer and a second electrode layer arranged on a side of the piezoelectric layer away from the first electrode layer, a surface of the second electrode layer farthest from the first electrode layer being provided with a slit, the slit penetrating two opposite surfaces of the piezoelectric structure in the first direction, so as to divide the piezoelectric structure into at least two cantilever beams; A first slit is provided on the first electrode layer, and the first slit penetrates two opposite surfaces of the first electrode layer in the first direction. The narrow gap is located in the first slit, and the outline of the narrow gap does not intersect with the outline of the first slit.

2. The piezoelectric structure according to claim 1, characterized in that The first gap is filled with non-metallic material.

3. The piezoelectric structure according to claim 2, characterized in that: The piezoelectric layer closest to the first electrode layer is attached to the first electrode layer and fills the first gap.

4. The piezoelectric structure according to claim 1, characterized in that: At least one of the second electrode layers is provided with a second slit, the second slit runs through two opposite surfaces of the second electrode layer in the first direction, the narrow gap is located in the second slit and the outline of the narrow gap does not intersect with the outline of the second slit.

5. The piezoelectric structure according to claim 4, characterized in that: The second gap is filled with non-metallic material.

6. The piezoelectric structure according to claim 5, characterized in that Along the first direction, the piezoelectric layer of the next composite film layer is attached to the second electrode layer of the previous composite film layer and fills the second gap.

7. A piezoelectric MEMS microphone, characterized in that: Comprising the piezoelectric structure according to any one of claims 1 to 6.

8. A method for preparing a piezoelectric structure, characterized in that: include: Providing a supporting film layer, and forming a first electrode layer on the supporting film layer along a first direction, 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 the first direction; forming at least one group of composite film layers on the first electrode layer along the first direction, wherein the composite film layers cover the first gap, the composite film layers include a piezoelectric layer and a second electrode layer, and the second electrode layer is located on a side of the piezoelectric layer away from the first electrode layer; The second electrode layer on the top is etched in the direction of the supporting film layer to form a narrow gap that at least penetrates all the composite film layers and the first electrode layer, thereby dividing all the composite film layers and the first electrode layer into at least two cantilever beams, wherein the narrow gap is located within the first gap and the outline of the narrow gap does not intersect with the outline of the first gap.

9. The method for preparing a piezoelectric structure according to claim 8, characterized in that: The surface of the second electrode layer has a second slit, the second slit penetrates two opposite surfaces of the second electrode layer in the first direction, the narrow gap is also located in the second slit, and the outline of the narrow gap does not intersect with the outline of the second slit.

10. The method for preparing a piezoelectric structure according to claim 9, characterized in that: The step of providing a supporting film layer and forming a first electrode layer on the supporting film layer along a first direction, wherein a first gap is provided on the first electrode layer, comprises: Providing a supporting film layer, laying a layer of first electrode material on the supporting film layer, and patterning the first electrode material to form a first electrode layer having a first gap; The forming of at least one group of composite film layers on the first electrode layer along the first direction comprises: Laying a layer of piezoelectric material on the first electrode layer to form a piezoelectric layer, wherein the piezoelectric layer covers the surface of the first electrode layer and fills the first gap of the first electrode layer; or laying a layer of piezoelectric material on the second electrode layer to form a piezoelectric layer, wherein the piezoelectric layer covers the surface of the second electrode layer and fills the second gap of the second electrode layer; A layer of second electrode material is laid on the piezoelectric layer, and the second electrode material is patterned to form a second electrode layer with a second gap.

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