Filtering device for improving bonding force and manufacturing method thereof

Abstract

The invention discloses a filtering device for improving bonding force and a manufacturing method thereof. Relates to the technical field of filtering. The filtering device for improving the bonding force comprises a first substrate serving as a carrier, a filtering assembly and a second substrate serving as a cap, the filtering assembly is formed on one side of the first substrate, and the filtering assembly is provided with a first concave structure; and a bonding structure is arranged between the filtering assembly and the second substrate, covers at least part of the surface of the filtering assembly and fills the first sunken structure. The design not only increases the surface area of the bonding interface, but also enables the bonding material to penetrate into the filtering assembly more deeply, and enhances the bonding force between the bonding structure and the filtering assembly, thereby reducing the risk of separation of the bonding structure and the filtering assembly. Therefore, the technical problem that the bonding force between the bonding structure and the filtering assembly in the filtering device manufactured by adopting the D-BAW technology in the prior art is poor and separation is easily caused is solved.

Description

Technical Field

[0001] The present application relates to the field of filtering technology, and in particular to a filtering device with improved bonding strength and a manufacturing method thereof. Background Art

[0002] Bulk acoustic wave filter (BAW) is an electronic device that uses piezoelectric materials to filter acoustic wave signals. Its working principle is based on the inverse piezoelectric effect of piezoelectric bodies. It can convert electrical signals into acoustic wave signals and propagate in acoustic wave conductors. With the continuous development of BAW technology, double-side-patterning bulk acoustic wave filter (D-BAW) technology has emerged. The structure of this bulk acoustic wave filter is made by double-sided bonding. That is, during the production process, several steps of preparation process are first implemented on the front side of the wafer, and then the wafer is turned over by bonding to implement subsequent preparation processes. During packaging, the wafer is flipped over by bonding, and several steps of preparation process are implemented on the back side, thereby realizing the double-sided process in this way.

[0003] However, in the filter device made by D-BAW technology, the bonding structure between the filter component (whose core structure is composed of a positive electrode, a piezoelectric layer and a bottom electrode) and the substrate as a cap often faces a challenge. Specifically, the bonding surface between the bonding structure and the filter component is often designed to be flat, which may lead to poor bonding strength at the bonding interface and easily cause the bonding structure to separate from the filter component. This problem not only reduces the yield of the filter device, but also affects its overall reliability.

[0004] With regard to the problem that the bonding force between the bonding structure and the filter component in the existing filter device made by using D-BAW technology is poor and easily causes separation, no effective solution has been proposed so far. Summary of the invention

[0005] The embodiments of the present disclosure provide a filter device with improved bonding strength and a manufacturing method thereof, so as to at least solve the technical problem in the prior art that the bonding strength between the bonding structure and the filter component in the filter device made by using D-BAW technology is poor and easily causes separation.

[0006] According to one aspect of an embodiment of the present disclosure, a filtering device with improved bonding force is provided, comprising: a first substrate as a carrier, a filtering component, and a second substrate as a cap; wherein the filtering component is formed on one side of the first substrate, and the filtering component has a first recessed structure; and a bonding structure is provided between the filtering component and the second substrate, wherein the bonding structure covers at least a portion of the surface of the filtering component and fills the first recessed structure.

[0007] Optionally, the filtering component includes a piezoelectric layer, a first electrode, a second electrode and a first resonant cavity; wherein the first electrode is located on a side of the piezoelectric layer away from the first substrate; the second electrode is located on a side of the piezoelectric layer close to the first substrate; the first resonant cavity is formed between the piezoelectric layer and the first substrate; and the first recessed structure is arranged in the piezoelectric layer, and the bonding structure covers at least a portion of the surface of the piezoelectric layer and fills the first recessed structure.

[0008] Optionally, the filter component further includes a fence layer located between the first substrate and the piezoelectric layer, and the fence layer has a second recessed structure connected to the first recessed structure, and the bonding structure fills the second recessed structure.

[0009] Optionally, a width of the second recessed structure is greater than a width of the first recessed structure.

[0010] Optionally, a width difference between the second recessed structure and the first recessed structure is 5-20 um.

[0011] Optionally, the first recessed structure includes a first recessed portion and a second recessed portion, and the second recessed structure includes a third recessed portion and a fourth recessed portion; wherein the first recessed portion is located in the first region of the piezoelectric layer, and the second recessed portion is located in the second region of the piezoelectric layer; and the first region and the second region do not overlap with the first electrode and the second electrode in a first direction; the first direction is perpendicular to the plane where the first substrate is located; the third recessed portion is connected to the first recessed portion, and the first recessed portion at least partially overlaps with the third recessed portion in the first direction; and the fourth recessed portion is connected to the second recessed portion, and the second recessed portion at least partially overlaps with the fourth recessed portion in the first direction.

[0012] Optionally, the uniformity of the fence layer is required to be <5%.

[0013] Optionally, the bonding structure is made of a dry film.

[0014] According to another aspect of an embodiment of the present disclosure, a method for manufacturing a filter device with improved bonding force is also provided, comprising: manufacturing a first substrate as a carrier, a filter component, and a second substrate as a cap; wherein the filter component is formed on one side of the first substrate, and the filter component has a first recessed structure; and a bonding structure is provided between the filter component and the second substrate, wherein the bonding structure covers at least a portion of the surface of the filter component and fills the first recessed structure.

[0015] Optionally, the bonding structure is made of a dry film; and the steps of making the filtering component include: making a piezoelectric layer, a first electrode, a second electrode and a first resonant cavity; wherein the first electrode is located on a side of the piezoelectric layer away from the first substrate; the second electrode is located on a side of the piezoelectric layer close to the first substrate; the first resonant cavity is formed between the piezoelectric layer and the first substrate; and the steps of making the first recessed structure include: making the first recessed structure in the piezoelectric layer; the bonding structure covers at least a portion of the surface of the piezoelectric layer and fills the first recessed structure.

[0016] Optionally, the step of making the filter component also includes: making a fence layer located between the first substrate and the piezoelectric layer, the fence layer having a second recessed structure connected to the first recessed structure; the bonding structure fills the second recessed structure; wherein the width of the second recessed structure is greater than the width of the first recessed structure; the width difference between the second recessed structure and the first recessed structure is 5-20um; and the uniformity requirement of the fence layer is <5%.

[0017] Optionally, the step of making the first recessed structure specifically includes: making a first recessed portion and a second recessed portion; wherein the first recessed portion is located in the first region of the piezoelectric layer, and the second recessed portion is located in the second region of the piezoelectric layer; and the first region and the second region do not overlap with the first electrode and the second electrode in the first direction; the first direction is perpendicular to the plane where the first substrate is located; and the step of making the second recessed structure specifically includes: making a third recessed portion and a fourth recessed portion; wherein the third recessed portion is connected to the first recessed portion, and the first recessed portion at least partially overlaps with the third recessed portion in the first direction; the fourth recessed portion is connected to the second recessed portion, and the second recessed portion at least partially overlaps with the fourth recessed portion in the first direction.

[0018] In the filter device with improved bonding strength proposed in the present application, a first recessed structure is formed in the filter component, and the bonding structure between the filter component and the second substrate as a cap not only covers part of the surface of the filter component, but also extends and fills the first recessed structure. This design not only increases the surface area of ​​the bonding interface and provides more bonding points, but also enables the bonding material to penetrate deeper into the interior of the filter component, thereby effectively enhancing the bonding strength between the bonding structure and the filter component, greatly reducing the risk of separation of the bonding structure and the filter component, and improving the yield and overall reliability of the filter device. This solves the technical problem in the prior art that the bonding strength between the bonding structure and the filter component in the filter device made using D-BAW technology is poor, which easily causes separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present disclosure and constitute a part of the present application. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure. In the drawings: Figure 1-Figure 12 Schematic diagram of various structures during the manufacturing process of a filter device with improved bonding strength provided by one embodiment of the present application. DETAILED DESCRIPTION

[0020] In order to enable those skilled in the art to better understand the technical solutions of the present disclosure, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are only embodiments of a part of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present disclosure.

[0021] It should be noted that the terms "first", "second", etc. in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present disclosure described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products, or devices.

[0022] Secondly, the present application is described in detail with reference to the schematic diagram. When describing the embodiments of the present application in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present application. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0023] As described in the background technology section, in a filter device made using D-BAW technology, the bonding structure between the filter component (whose core structure is composed of a positive electrode, a piezoelectric layer, and a bottom electrode) and the substrate as a cap often faces a challenge. Specifically, the bonding surface between the bonding structure and the filter component is often designed to be flat, which may result in poor bonding strength at the bonding interface and easily cause the bonding structure to separate from the filter component. This problem not only reduces the yield of the filter device, but also affects its overall reliability.

[0024] In view of this, an embodiment of the present application provides a filter device with improved bonding strength and a method for manufacturing the same, so as to solve the problem of poor bonding strength between the bonding structure and the filter component in the filter device, which easily causes separation, and improve the yield and reliability of the filter device.

[0025] In the following, the filter device for improving bonding strength and the manufacturing method thereof provided by the embodiment of the present application are described in conjunction with specific embodiments. For ease of understanding, the present application first describes the manufacturing method of the filter device for improving bonding strength.

[0026] The manufacturing method of the filter device with improved bonding strength provided in the embodiment of the present application includes: manufacturing a first substrate as a carrier, a filter component and a second substrate as a cap; wherein the filter component is formed on one side of the first substrate, and the filter component has a first recessed structure; and a bonding structure is provided between the filter component and the second substrate, and the bonding structure covers at least part of the surface of the filter component and fills the first recessed structure. Thus, the first recessed structure can be formed in the filter component, and the bonding structure between the filter component and the second substrate as a cap not only covers part of the surface of the filter component, but also extends and fills the first recessed structure. This design not only increases the surface area of ​​the bonding interface and provides more bonding points, but also enables the bonding material to penetrate deeper into the interior of the filter component, effectively enhancing the bonding strength between the bonding structure and the filter component, greatly reducing the risk of separation of the bonding structure from the filter component, and improving the yield and overall reliability of the filter device.

[0027] It should be noted that, in this embodiment, the filtering device for improving bonding strength includes: a first substrate as a carrier, a filtering component and a second substrate as a cap; wherein the filtering component is formed on one side of the first substrate, and the filtering component has a first recessed structure; and there is a bonding structure between the filtering component and the second substrate, and the bonding structure covers at least a portion of the surface of the filtering component and fills the first recessed structure.

[0028] Specifically, the method for manufacturing a filter device with improved bonding strength provided in the embodiment of the present application includes: like Figure 1 As shown, a first electrode layer 120, a piezoelectric layer 130 and a second electrode layer 140 are sequentially fabricated on a third substrate 110 used as a temporary substrate. The first electrode layer 120 is used to fabricate a first electrode, and the second electrode layer 140 is used to fabricate a second electrode.

[0029] Optionally, in one embodiment of the present application, the third substrate 110 is a silicon substrate, a silicon-on-insulator substrate, a glass substrate, a silicon carbide substrate, or a gallium arsenide (GaAs) substrate, etc.; The first electrode layer 120 may be an Al layer, a Cu layer, a Mo layer, an Au layer or a Pt layer, and may be formed by a physical vapor deposition (PVD) process; similarly, the second electrode layer 140 may be an Al layer, a Cu layer, a Mo layer, an Au layer or a Pt layer, and may be formed by a physical vapor deposition (PVD) process; The piezoelectric layer 130 can be an AlN layer, a scandium-doped aluminum nitride (AlxSc1-xN) layer, a lithium niobate (LiNbO3) layer, a lithium tantalate (LiTaO3) layer or a quartz layer, etc. It can be a polycrystalline layer or a single crystal layer, and can be formed by PVD or metal organic chemical vapor deposition (MOCVD) or the like.

[0030] like Figure 2 As shown, the first area of ​​the second electrode layer 140 is etched to expose a portion of the surface of the piezoelectric layer 130 to form a second electrode 141. The second electrode 141 is located in the middle area of ​​the first side of the piezoelectric layer 130.

[0031] Specifically, in one embodiment of the present application, the process of etching the second electrode layer 140 may be a dry etching process or a wet etching process, but the present application does not limit this and it depends on the specific situation.

[0032] like Figure 3 As shown, a filling layer 150 is formed on the side of the second electrode layer 140 away from the third substrate 110, and the filling layer 150 covers at least a portion of the exposed surface of the piezoelectric layer 130 and at least a portion of the second electrode 141. Optionally, the material of the filling layer 150 can be SiO2, PSG, USG, a-Si or photoresist, etc.; the formation process of the filling layer 150 can be PVD, CVD or spin coating, etc.

[0033] like Figure 4 As shown, a fence layer 160 is formed on a side of the filling layer 150 away from the third substrate 110 , and the fence layer 160 covers the exposed surface of the piezoelectric layer 130 , the exposed surface of the second electrode 141 , and the exposed surface of the filling layer 150 .

[0034] Optionally, the uniformity of the fence layer 160 is required to be <5%.

[0035] like Figure 5As shown, the fence layer 160 is etched to form a second recessed structure 161 in the fence layer 160, wherein the second recessed structure 161 penetrates the fence layer 160 and exposes a portion of the surface of the piezoelectric layer 130. Optionally, the second recessed structure 161 includes a third recessed portion 1611 and a fourth recessed portion 1612, the third recessed portion 1611 is located in the first region of the fence layer 160, the fourth recessed portion 1612 is located in the second region of the fence layer 160, and the first region and the second region do not overlap with the second electrode 141 and the filling layer 150 in the first direction. Specifically, the etching process of the fence layer 160 can be dry etching or wet etching. Wherein, the first direction is perpendicular to the plane where the third substrate 110 is located; like Figure 6 As shown, a first substrate 170 as a carrier is bonded to the side of the fence layer 160 away from the piezoelectric layer 130. Similarly, the first direction is also perpendicular to the plane where the first substrate 170 is located; like Figure 7 As shown, the wafer composed of the various structures obtained above is flipped over, and the third substrate 110 is removed from the side of the third substrate 110 away from the first substrate 170. Optionally, the removal process of the third substrate 110 can be grinding or chemical mechanical polishing (CMP), which is not limited in the present application and depends on the specific circumstances.

[0036] like Figure 8 As shown, part of the first electrode layer 120 is etched to expose part of the surface of the piezoelectric layer 130 to form a first electrode 121. The first electrode 121 is located in the middle area of ​​the second side of the piezoelectric layer 130.

[0037] Optionally, the etching process of the first electrode layer 120 may be wet etching or dry etching.

[0038] like Fig. 9 As shown, the piezoelectric layer 130 is etched by photolithography technology to form a first recessed structure 131 in the exposed portion of the piezoelectric layer 130, wherein the first recessed structure 131 penetrates the piezoelectric layer 130 and is connected to the second recessed structure 161. Optionally, the first recessed structure 131 includes a first recessed portion 1311 and a second recessed portion 1312, wherein the first recessed portion 1311 is located in a first region of the piezoelectric layer 130, the second recessed portion 1312 is located in a second region of the piezoelectric layer 130, and the first region and the second region do not overlap with the first electrode 121 and the second electrode 141 in a first direction; the first direction is perpendicular to the plane where the first substrate 170 is located.

[0039] Optionally, the third recessed portion 1611 is connected to the first recessed portion 1311, and the first recessed portion 1311 at least partially overlaps with the third recessed portion 1611 in the first direction. The fourth recessed portion 1612 is connected to the second recessed portion 1312, and the second recessed portion 1312 at least partially overlaps with the fourth recessed portion 1612 in the first direction.

[0040] Optionally, the width of the second concave structure 161 is greater than the width of the first concave structure 131. Thus, the bonding structure 180 and the bonding surfaces of the piezoelectric layer 130 and the fence layer 160 together form a concave-convex structure, further enhancing the bonding force between the bonding structure and the filter assembly.

[0041] Optionally, a width difference between the second recessed structure 161 and the first recessed structure 131 is 5-20 um.

[0042] Optionally, the first recessed structure 131 may be formed by a wet etching process or a dry etching process.

[0043] like Fig.10 As shown, the filling layer 150 is released to form a first resonant cavity 1501 , wherein at least a portion of the first resonant cavity 1501 is in contact with the piezoelectric layer 130 , and another portion of the first resonant cavity 1501 is in contact with the second electrode 141 .

[0044] Specifically, in one embodiment of the present application, the filling layer 150 is released by liquid phase etching or gas phase etching to form the first resonant cavity 1501. The specific operations include: Using a liquid phase etching solution such as a hydrofluoric acid solution (HF) or a buffered oxide etchant (BOE) to etch the filling layer 150 to form a first resonant cavity 1501; Alternatively, the filling layer 150 is etched using gas such as gaseous hydrogen fluoride (HF) or xenon difluoride (XeF 2 ) to form the first resonant cavity 1501 .

[0045] It should be noted that, in this embodiment, the piezoelectric layer 130 , the first electrode 121 , the second electrode 141 and the first resonant cavity 1501 constitute a filtering component.

[0046] like Fig.11 As shown, a bonding structure 180 is formed, and the bonding structure 180 covers at least a portion of the surface of the filter component and fills the first recessed structure 131. Specifically, the bonding structure 180 covers at least a portion of the surface of the piezoelectric layer 130 and fills the first recessed structure 131 and the second recessed structure 161.

[0047] Optionally, the bonding structure 180 is made of a dry film. The fluidity of the dry film itself enables it to better adapt to and fill the first recessed structure 131 and the second recessed structure 161, thereby achieving a more secure bonding method.

[0048] Optionally, the material of the dry film is usually polyimide, and may also be organic materials such as BCB (Benzocyclobutene) and epoxy resin.

[0049] It should be noted that, in this embodiment, the bonding structure 180 does not cover at least a portion of the exposed surface of the first electrode 121 and the piezoelectric layer 130 .

[0050] like Fig.12 As shown, a second substrate 190 is bonded to the bonding structure 180 at a side away from the piezoelectric layer 130 as a cap, wherein the area defined by the second substrate 190, the bonding structure 180, the first electrode 121 and the piezoelectric layer 130 is a second resonant cavity 1801. Optionally, the material of the second substrate 190 may be silicon, glass, SiC, GaAs, etc., which is not limited in the present application and depends on the specific circumstances.

[0051] In addition, the embodiments of the present application also provide a filter device with improved bonding strength manufactured using the manufacturing method provided by any of the above embodiments.

[0052] like Fig.12 As shown, the filter device with improved bonding strength provided in the embodiment of the present application includes: a first substrate 170 as a carrier, a filter component and a second substrate 190 as a cap; wherein the filter component is formed on one side of the first substrate 170, and the filter component has a first recessed structure 131; and a bonding structure 180 is provided between the filter component and the second substrate 190, and the bonding structure 180 covers at least a portion of the surface of the filter component and fills the first recessed structure 131.

[0053] Optionally, the filtering component includes a piezoelectric layer 130, a first electrode 121, a second electrode 141 and a first resonant cavity 1501; wherein the first electrode 121 is located on a side of the piezoelectric layer 130 away from the first substrate 170; the second electrode is located on a side of the piezoelectric layer close to the first substrate 170; the first resonant cavity 1501 is formed between the piezoelectric layer 130 and the first substrate 170; and the first recessed structure 131 is arranged in the piezoelectric layer 130, and the bonding structure 180 covers at least a portion of the surface of the piezoelectric layer 130 and fills the first recessed structure 131.

[0054] Optionally, the filter component further includes a fence layer 160 located between the first substrate 170 and the piezoelectric layer 130 , and a second recessed structure 161 connected to the first recessed structure 131 is provided in the fence layer 160 , and the bonding structure 180 fills the second recessed structure 161 .

[0055] Optionally, a width of the second recessed structure 161 is greater than a width of the first recessed structure 131 .

[0056] Optionally, a width difference between the second recessed structure 161 and the first recessed structure 131 is 5-20 um.

[0057] Optionally, the first recessed structure 131 includes a first recessed portion 1311 and a second recessed portion 1312, and the second recessed structure 161 includes a third recessed portion 1611 and a fourth recessed portion 1612; wherein, the first recessed portion 1311 is located in the first region of the piezoelectric layer 130, and the second recessed portion 1312 is located in the second region of the piezoelectric layer 130; and, the first region and the second region do not overlap with the first electrode 121 and the second electrode 141 in the first direction; the third recessed portion 1611 is connected to the first recessed portion 1311, and the first recessed portion 1311 at least partially overlaps with the third recessed portion 1611 in the first direction; and the fourth recessed portion 1612 is connected to the second recessed portion 1312, and the second recessed portion 1312 at least partially overlaps with the fourth recessed portion 1612 in the first direction.

[0058] Optionally, the uniformity of the fence layer 160 is required to be <5%.

[0059] Optionally, the bonding structure 180 is made of a dry film.

[0060] In summary, in the filter device with improved bonding strength and its manufacturing method provided in the embodiment of the present application, a first recessed structure is formed in the filter component, and the bonding structure between the filter component and the second substrate as a cap not only covers part of the surface of the filter component, but also extends and fills the first recessed structure. This design not only increases the surface area of ​​the bonding interface and provides more bonding points, but also enables the bonding material to penetrate deeper into the interior of the filter component, thereby effectively enhancing the bonding strength between the bonding structure and the filter component, greatly reducing the risk of separation of the bonding structure and the filter component, and improving the yield and overall reliability of the filter device. This solves the technical problem in the prior art that the bonding strength between the bonding structure and the filter component in the filter device made using D-BAW technology is poor, which easily causes separation.

[0061] The various parts in this manual are described in a progressive manner, and each part focuses on the differences from other parts. The same or similar parts between the various parts can be referenced to each other.

[0062] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A filter device for improving bonding strength, characterized in that: include: A first substrate as a carrier, a filter assembly, and a second substrate as a cap; in The filter component is formed on one side of the first substrate, and the filter component has a first recessed structure; and A bonding structure is provided between the filter component and the second substrate, and the bonding structure covers at least a portion of the surface of the filter component and fills the first recessed structure.

2. The filtering device according to claim 1, characterized in that The filter assembly comprises a piezoelectric layer, a first electrode, a second electrode and a first resonant cavity; wherein the first electrode is located on a side of the piezoelectric layer away from the first substrate; the second electrode is located on a side of the piezoelectric layer close to the first substrate; the first resonant cavity is formed between the piezoelectric layer and the first substrate; Furthermore, the first recessed structure is disposed in the piezoelectric layer, and the bonding structure covers at least a portion of a surface of the piezoelectric layer and fills the first recessed structure.

3. The filtering device according to claim 2, characterized in that: The filter assembly further includes a fence layer located between the first substrate and the piezoelectric layer, and the fence layer has a second recessed structure connected to the first recessed structure, and the bonding structure fills the second recessed structure.

4. The filtering device according to claim 3, characterized in that: The width of the second recessed structure is greater than the width of the first recessed structure.

5. The filtering device according to claim 4, characterized in that The width difference between the second recessed structure and the first recessed structure is 5-20 um.

6. The filtering device according to claim 3, characterized in that: The first recessed structure includes a first recessed portion and a second recessed portion, and the second recessed structure includes a third recessed portion and a fourth recessed portion; The first recessed portion is located in a first region of the piezoelectric layer, and the second recessed portion is located in a second region of the piezoelectric layer; and the first region and the second region do not overlap with the first electrode and the second electrode in a first direction; and the first direction is perpendicular to a plane where the first substrate is located; The third recessed portion is in communication with the first recessed portion, and the first recessed portion at least partially overlaps with the third recessed portion in the first direction; and The fourth recessed portion is communicated with the second recessed portion, and the second recessed portion at least partially overlaps with the fourth recessed portion in the first direction.

7. The filtering device according to claim 3, characterized in that: The uniformity requirement for the fence layer is <5%.

8. The filtering device according to claim 1, characterized in that: The bonding structure is made of a dry film.

9. A method for manufacturing a filter device with improved bonding strength, characterized in that: include: Manufacturing a first substrate as a carrier, a filter assembly, and a second substrate as a cap; The filter component is formed on one side of the first substrate, and has a first recessed structure; A bonding structure is provided between the filter component and the second substrate, and the bonding structure covers at least a portion of the surface of the filter component and fills the first recessed structure.

10. The manufacturing method according to claim 9, characterized in that: The bonding structure is made of a dry film; Furthermore, the steps of manufacturing the filter component include: manufacturing a piezoelectric layer, a first electrode, a second electrode and a first resonant cavity; wherein the first electrode is located on a side of the piezoelectric layer away from the first substrate; the second electrode is located on a side of the piezoelectric layer close to the first substrate; the first resonant cavity is formed between the piezoelectric layer and the first substrate; and The step of making the first recessed structure includes: making the first recessed structure in the piezoelectric layer; and the bonding structure covers at least a portion of the surface of the piezoelectric layer and fills the first recessed structure.

11. The manufacturing method according to claim 10, characterized in that: The step of making the filtering component also includes: making a fence layer located between the first substrate and the piezoelectric layer, the fence layer having a second recessed structure connected to the first recessed structure; the bonding structure fills the second recessed structure; wherein the width of the second recessed structure is greater than the width of the first recessed structure; the width difference between the second recessed structure and the first recessed structure is 5-20um; the uniformity requirement of the fence layer is <5%.

12. The manufacturing method according to claim 11, characterized in that: The step of making the first recessed structure specifically includes: making a first recessed portion and a second recessed portion; wherein the first recessed portion is located in a first region of the piezoelectric layer, and the second recessed portion is located in a second region of the piezoelectric layer; and the first region and the second region do not overlap with the first electrode and the second electrode in a first direction; and the first direction is perpendicular to the plane where the first substrate is located; and The steps of making the second recessed structure specifically include: making a third recessed portion and a fourth recessed portion; wherein the third recessed portion is connected to the first recessed portion, and the first recessed portion at least partially overlaps with the third recessed portion in the first direction; the fourth recessed portion is connected to the second recessed portion, and the second recessed portion at least partially overlaps with the fourth recessed portion in the first direction.

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