Bulk acoustic wave filter packaging structure, preparation method thereof and radio frequency equipment

Abstract

The invention provides a bulk acoustic wave filter packaging structure, a preparation method thereof and radio frequency equipment, and relates to the technical field of semiconductors. The packaging cover plate is provided with a groove area, and the orthographic projection of the groove area in the first direction at least covers the orthographic projection of the working area of the bulk acoustic wave filter, so that a cavity area required by the bulk acoustic wave filter packaging structure is formed. An annular enclosing wall structure is arranged between the bulk acoustic wave filter and the packaging cover plate to achieve the purpose of isolating water vapor, so that the air tightness is better. Based on the characteristics of the packaging cover plate and the dry film, the strength of the packaging cover plate is higher than that of the dry film, in the layout process, the packaging cover plate only needs to form a circle around the chip based on the cavity area, compared with an existing dry film packaging technology, the area of the chip can be smaller, and the supporting problem does not need to be considered. In general, compared with the prior art, the technical scheme has the advantages that the stability, the supporting performance, the air tightness and the like are greatly improved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a bulk acoustic wave filter packaging structure and a preparation method thereof, and a radio frequency device. Background Art

[0002] BAW (Bulk Acoustic Wave) filter is the abbreviation of bulk acoustic wave filter. When an alternating electric field is applied to both ends of a piezoelectric material, the piezoelectric material will generate mechanical vibrations. This vibration propagates inside the piezoelectric material in the form of bulk acoustic waves. By cleverly designing the structure and size, bulk acoustic waves of a specific frequency can propagate smoothly in the filter, while suppressing sound waves of other frequencies, thereby achieving a filtering function. It is widely used in a variety of fields, such as the radio frequency field.

[0003] At present, the BAW filter packaging structure is bonded to the BAW filter by sticking a dry film on the packaging cover to form a cavity area above the working area of ​​the BAW filter. At this time, the setting of the dry film also plays a supporting and sealing function.

[0004] However, since the material of the dry film is usually organic material, it cannot completely isolate water vapor; and since the dry film is not rigid enough, in order to improve the strength of the dry film support, the width of the dry film is usually increased. Obviously, this operation is not conducive to the miniaturization design of the chip.

[0005] Therefore, how to optimize the BAW filter packaging structure is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] In view of the above problems, the present application provides a bulk acoustic wave filter packaging structure and a preparation method thereof, and a radio frequency device, so as to achieve the purpose of improving the stability of the bulk acoustic wave filter packaging structure and reducing the chip area. The specific scheme is as follows:

[0007] A first aspect of the present application provides a bulk acoustic wave filter packaging structure, the bulk acoustic wave filter packaging structure comprising:

[0008] A bulk acoustic wave filter and a packaging cover plate are arranged opposite to each other; the bulk acoustic wave filter has a working area, and the packaging cover plate includes a groove area arranged toward one side of the bulk acoustic wave filter; in a first direction, the orthographic projection of the groove area at least covers the orthographic projection of the working area; the first direction is perpendicular to the plane where the bulk acoustic wave filter is located;

[0009] an annular wall structure located between the BAW filter and the packaging cover plate and on the BAW filter;

[0010] Wherein, the working area and the groove area are both located inside the annular wall structure.

[0011] Preferably, in the above-mentioned BAW filter packaging structure, the material of the annular wall structure is a metal material or an inorganic material.

[0012] Preferably, in the above-mentioned BAW filter packaging structure, the width of the annular wall structure is in the range of 2 μm-5 μm;

[0013] The thickness of the annular wall structure is in the range of 1 μm to 2 μm.

[0014] Preferably, in the above BAW filter packaging structure, the depth of the groove region ranges from 5 μm to 15 μm.

[0015] Preferably, in the above-mentioned bulk acoustic wave filter packaging structure, the packaging cover plate is a Si cover plate.

[0016] Preferably, in the above-mentioned BAW filter packaging structure, the BAW filter packaging structure further comprises:

[0017] a pad structure located between the BAW filter and the package cover plate and on the BAW filter;

[0018] The pad structure is located inside the annular wall structure.

[0019] Preferably, in the above BAW filter packaging structure, the pad structure has a thickness ranging from 1 μm to 2 μm.

[0020] Preferably, in the above-mentioned BAW filter packaging structure, the BAW filter packaging structure further comprises:

[0021] A first through hole passes through the BAW filter, wherein the first through hole exposes a portion of a surface of the pad structure.

[0022] Preferably, in the above-mentioned BAW filter packaging structure, the BAW filter packaging structure further comprises:

[0023] An RDL lead structure is electrically connected to the pad structure through the first through hole.

[0024] Preferably, in the above-mentioned BAW filter packaging structure, the BAW filter packaging structure further comprises:

[0025] A protective layer is located on a side of the BAW filter away from the package cover plate; the protective layer has a second through hole, and the second through hole exposes a portion of the surface of the RDL lead structure.

[0026] Preferably, in the above-mentioned BAW filter packaging structure, the BAW filter packaging structure further comprises:

[0027] A solder ball is located on a side of the BAW filter away from the package cover plate; the solder ball is electrically connected to the RDL lead structure.

[0028] A second aspect of the present application provides a method for preparing a bulk acoustic wave filter packaging structure, the method for preparing the bulk acoustic wave filter packaging structure comprising:

[0029] Providing an integrated acoustic wave filter, the bulk acoustic wave filter having a working area and an annular wall structure located on the bulk acoustic wave filter;

[0030] Providing a packaging cover plate, and processing the packaging cover plate to form a groove area;

[0031] The packaging cover plate is bonded to the BAW filter; after the bonding is completed, the groove area faces one side of the BAW filter, and the annular wall structure is located between the BAW filter and the packaging cover plate; in a first direction, the orthographic projection of the groove area at least covers the orthographic projection of the working area; the first direction is perpendicular to the plane where the BAW filter is located; wherein the working area and the groove area are both located inside the annular wall structure.

[0032] Preferably, in the method for preparing the BAW filter packaging structure, bonding the packaging cover plate to the BAW filter comprises:

[0033] The packaging cover plate is bonded to the BAW filter by applying glue.

[0034] Preferably, in the method for preparing the BAW filter packaging structure, bonding the packaging cover plate to the BAW filter by applying glue comprises:

[0035] Under the conditions of a temperature range of 130° C.-170° C. and a pressure range of 4000N-6000N, the packaging cover plate and the BAW filter are bonded by applying glue.

[0036] Preferably, in the method for preparing the above-mentioned BAW filter packaging structure, the BAW filter packaging structure further comprises: a pad structure located between the BAW filter and the packaging cover plate and located on the BAW filter; the pad structure is located inside the annular wall structure;

[0037] The method for preparing the BAW filter packaging structure further comprises:

[0038] The BAW filter is processed to form a first through hole penetrating the BAW filter, wherein the first through hole exposes a portion of the surface of the pad structure.

[0039] Preferably, in the method for preparing the above-mentioned BAW filter packaging structure, the method for preparing the BAW filter packaging structure further comprises:

[0040] An RDL lead structure is formed, wherein the RDL lead structure is electrically connected to the pad structure through the first through hole.

[0041] Preferably, in the method for preparing the above-mentioned BAW filter packaging structure, the method for preparing the BAW filter packaging structure further comprises:

[0042] A protection layer is formed on a side of the BAW filter away from the package cover plate; the protection layer has a second through hole, and the second through hole exposes a portion of the surface of the RDL lead structure.

[0043] Preferably, in the method for preparing the above-mentioned BAW filter packaging structure, the method for preparing the BAW filter packaging structure further comprises:

[0044] A solder ball is formed on a side of the BAW filter away from the package cover plate; the solder ball is electrically connected to the RDL lead structure.

[0045] A third aspect of the present application provides a radio frequency device, which includes the bulk acoustic wave filter packaging structure described in any one of the above items.

[0046] With the help of the above technical solution, the present application provides a bulk acoustic wave filter packaging structure and a preparation method thereof, and a radio frequency device. The packaging cover is provided with a groove area. In the first direction, the orthographic projection of the groove area at least covers the orthographic projection of the working area of ​​the bulk acoustic wave filter, thereby forming the cavity area required for the bulk acoustic wave filter packaging structure.

[0047] An annular wall structure is arranged between the BAW filter and the packaging cover plate to isolate water vapor and improve the air tightness of the BAW filter packaging structure.

[0048] Based on the characteristics of the packaging cover and the dry film, it can be seen that the strength of the packaging cover is stronger than that of the dry film. During the layout process, the packaging cover based on the cavity area only needs to form a circle around the chip. Compared with the existing dry film packaging technology, the chip area can be made smaller and there is no need to consider support issues.

[0049] In general, the technical solution of the present application has a huge improvement in stability, support, airtightness and other aspects compared with the existing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. Throughout the accompanying drawings, the same or similar reference numerals represent the same or similar elements. It should be understood that the drawings are schematic and the originals and elements are not necessarily drawn to scale.

[0051] Figure 1 A schematic structural diagram of a bulk acoustic wave filter packaging structure provided by an embodiment of the present invention;

[0052] Figure 2 A schematic structural diagram of another bulk acoustic wave filter packaging structure provided by an embodiment of the present invention;

[0053] Figure 3 A schematic flow chart of a method for preparing a bulk acoustic wave filter packaging structure provided by an embodiment of the present invention;

[0054] Figure 4-Figure 9 for Figure 3 Schematic diagram of the partial structure corresponding to the preparation method shown. DETAILED DESCRIPTION

[0055] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application. The terms used in the implementation mode of the present application are only used to explain the specific embodiments of the present application, and are not intended to limit the present application. It is known to those skilled in the art that with the development of technology and the emergence of new scenarios, the technical solutions provided in the embodiments of the present application are also applicable to similar technical problems.

[0056] It should be noted that the directional words appearing in the present invention are based on the relative position relationship shown in the drawings and cannot be used as an absolute limitation to the present application.

[0057] Based on bulk acoustic wave filters, when an alternating electric field is applied to both ends of a piezoelectric material, the piezoelectric material will generate mechanical vibrations. This vibration propagates inside the piezoelectric material in the form of bulk acoustic waves. By cleverly designing the structure and size, bulk acoustic waves of a specific frequency can propagate smoothly in the filter, while suppressing sound waves of other frequencies, thereby achieving a filtering function. It is widely used in a variety of fields, such as the radio frequency field.

[0058] BAW filters have an irreplaceable position in the field of high-frequency communications. In 5G, 5.5G and even future 6G devices, it is the core component of the RF front end, responsible for accurate filtering of high-frequency signals. In 5G devices, BAW filters are like a "signal guard" that can effectively filter out interference signals in the 5G frequency band, greatly improving the transmission quality and speed of signals. In base stations and routers, BAW filters also play a key role. Taking 5G base stations as an example, it can help base stations accurately transmit and receive 5G signals, improving the signal processing capabilities and coverage of base stations. Not only that, BAW filters can also be seen in wireless connection terminals such as IoT devices and smart wearable devices. For example, smart watches can filter out unnecessary signals and improve the communication performance and battery life of watches.

[0059] At present, the BAW filter packaging structure is bonded to the BAW filter by sticking a dry film on the packaging cover to form a cavity area above the working area of ​​the BAW filter. At this time, the setting of the dry film also plays a supporting and sealing function.

[0060] However, since the material of the dry film is usually organic material, it cannot completely isolate water vapor; and since the dry film is not rigid enough, in order to improve the strength of the dry film support, the width of the dry film is usually increased. Obviously, this operation is not conducive to the miniaturization design of the chip.

[0061] Based on this, the embodiment of the present invention provides a bulk acoustic wave filter packaging structure and a preparation method thereof, and a radio frequency device, so as to achieve the purpose of improving the stability of the bulk acoustic wave filter packaging structure and reducing the chip area. In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0062] refer to Figure 1 , Figure 1 A schematic diagram of a bulk acoustic wave filter packaging structure provided by an embodiment of the present invention, referring to Figure 2 , Figure 2 A schematic diagram of another bulk acoustic wave filter packaging structure provided in an embodiment of the present invention. The bulk acoustic wave filter packaging structure provided in an embodiment of the present invention includes:

[0063] A bulk acoustic wave filter 11 and a packaging cover plate 12 are arranged opposite to each other; the bulk acoustic wave filter 11 has a working area 13, and the packaging cover plate 12 includes a groove area 14 arranged toward one side of the bulk acoustic wave filter 11; in a first direction X, the orthographic projection of the groove area 14 at least covers the orthographic projection of the working area 13; the first direction X is perpendicular to the plane where the bulk acoustic wave filter 11 is located.

[0064] An annular wall structure 15 is located between the BAW filter 11 and the packaging cover plate 12 and on the BAW filter 11 .

[0065] The working area 13 and the groove area 14 are both located inside the annular wall structure 15 .

[0066] Specifically, in the embodiment of the present invention, the BAW filter packaging structure is mainly divided into two parts from a structural point of view, namely, Device Wafer and Cap Wafer. The Device Wafer is the part where the BAW filter 11 is located, which is the main working area of ​​the filter; the Cap Wafer is a structural component buckled on the Device Wafer for wafer-level packaging, namely, the packaging cover plate 12 described in the embodiment of the present application. In other words, the BAW filter packaging structure provided by the technical solution of the present application belongs to a wafer-level packaging structure.

[0067] In the embodiment of the present invention, the package cover plate 12 includes but is not limited to a Si cover plate, that is, the package cover plate 12 can be processed from a Si wafer.

[0068] The packaging cover plate 12 is provided with a groove area 14. In the first direction X, the orthographic projection of the groove area 14 at least covers the orthographic projection of the working area 13 of the BAW filter 11, thereby forming a cavity area required for the BAW filter packaging structure.

[0069] An annular wall structure 15 is provided between the BAW filter 11 and the package cover plate 12 to isolate water vapor and improve the air tightness of the BAW filter package structure. In an optional embodiment of the present invention, the material of the annular wall structure 15 is a metal material or an inorganic material, which has a better effect of isolating water vapor and a lower cost than a dry film of an organic material, and can meet the high reliability requirements of subsequent industrial and automotive electronic products.

[0070] Based on the characteristics of the packaging cover plate 12 and the dry film, it can be known that the strength of the packaging cover plate 12 is stronger than that of the dry film. In the process of layout, based on the cavity area, the packaging cover plate 12 only needs to form a circle around the chip. Compared with the existing dry film packaging technology, the chip area can be made smaller, and there is no need to consider support issues. In other words, based on the existing dry film packaging technology, in order to increase the strength of the dry film support, the width of the dry film is usually increased. Obviously, this operation is not conducive to the miniaturization design of the chip. Since there is no problem of support strength in the embodiment of the present application, it can also indirectly illustrate that the technical solution of the present application has also greatly improved in the aspect of chip miniaturization design compared with the existing dry film packaging technology.

[0071] In general, the technical solution of the present application has a huge improvement in stability, support, airtightness and other aspects compared with the existing technology.

[0072] Optionally, the width of the annular wall structure 15 ranges from 2 μm to 5 μm; exemplary widths of the annular wall structure 15 are 2 μm, 3.5 μm or 5 μm, etc. The selection of specific parameters may be determined according to actual conditions and is not limited in the embodiments of the present invention.

[0073] Optionally, the thickness of the annular wall structure 15 ranges from 1 μm to 2 μm; exemplary thickness of the annular wall structure 15 is 1 μm, 1.5 μm or 2 μm, etc. The selection of specific parameters can be determined according to actual conditions and is not limited in the embodiments of the present invention.

[0074] Optionally, the depth of the groove region 14 ranges from 5 μm to 15 μm; exemplary depths of the groove region 14 are 5 μm, 10 μm, 12.5 μm or 15 μm, etc. The selection of specific parameters may be determined according to actual conditions and is not limited in the embodiments of the present invention.

[0075] In an optional embodiment of the present invention, Figure 1 As shown, the BAW filter packaging structure provided by the embodiment of the present invention further includes: a pad structure 16 located between the BAW filter 11 and the packaging cover plate 12 and located on the BAW filter 11 .

[0076] The pad structure 16 is located inside the annular wall structure 15 .

[0077] The BAW filter packaging structure provided by the embodiment of the present invention further includes:

[0078] A first through hole 17 that penetrates the BAW filter 11 exposes a portion of the surface of the pad structure 16. It should be noted that the first through hole 17 is also called a TSV (Through Silicon Via) hole in the field. Based on the BAW filter packaging structure provided in the embodiment of the present application, the first through hole 17 penetrates the BAW filter 11 instead of penetrating the packaging cover 12, that is, this hole opening method is equivalent to the design of opening a TSV hole on the back.

[0079] The BAW filter packaging structure provided by the embodiment of the present invention further includes:

[0080] An RDL (full name: ReDistribution Layer) lead structure 18 , wherein the RDL lead structure 18 is electrically connected to the pad structure 16 through the first through hole 17 .

[0081] The BAW filter packaging structure provided by the embodiment of the present invention further includes:

[0082] A protective layer 19 is located on the side of the BAW filter 11 away from the package cover plate 12; the protective layer 19 has a second through hole, and the second through hole exposes a portion of the surface of the RDL lead structure 18. The protective layer 19 includes but is not limited to a polyimide layer, and its main function is to protect the RDL lead structure 18, buffer the stress generated during the packaging process, prevent overcurrent, etc., so as to improve the stability and reliability of the BAW filter packaging structure.

[0083] A solder ball 20 is located on a side of the BAW filter 11 away from the package cover plate 12 ; the solder ball 20 is electrically connected to the RDL lead structure 18 .

[0084] Specifically, in the embodiment of the present invention, the thickness of the pad structure 16 is in the range of 1 μm-2 μm. For example, the thickness of the pad structure 16 is 1 μm, 1.5 μm or 2 μm. The material of the pad structure 16 includes but is not limited to metal materials. For example, the material of the pad structure 16 is copper material or aluminum material. In the embodiment of the present invention, the function of the pad structure 16 is to electrically interconnect the bulk acoustic wave filter 11 with other external components. For example, the electrical interconnection between the bulk acoustic wave filter 11 and other external components is achieved by setting the pad structure 16 in combination with the RDL lead structure 18 and the solder ball 20.

[0085] like Figure 2 As shown, a structure including four pads 16 is used as an example for explanation. Among them, TSV technology can greatly improve the integration of electronic components, reduce the geometric size and weight of the package, and meet the requirements of microelectronic products for multi-function and miniaturization; because TSV technology can greatly shorten the length of electrical interconnection, it can solve the problem of signal delay and improve the electrical performance of the device. RDL technology is a technology used to redistribute electrical connections during chip packaging. By forming an additional wiring layer on the chip surface or other layers, the input / output position of the chip is redistributed to adapt to different packaging requirements and improve the flexibility of electrical connections.

[0086] It should be noted that Figure 1 The reference numeral 21 indicates glue, which indicates that in an optional embodiment of the present application, the packaging cover plate 12 and the BAW filter 11 are bonded together by applying the glue 21 .

[0087] Based on the above embodiments of the present invention, another embodiment of the present invention further provides a method for preparing a bulk acoustic wave filter packaging structure, referring to Figure 3 , Figure 3A schematic flow chart of a method for preparing a bulk acoustic wave filter packaging structure provided by an embodiment of the present invention. The method for preparing a bulk acoustic wave filter packaging structure provided by an embodiment of the present invention comprises:

[0088] S101: Figure 4 As shown, an integrated acoustic wave filter 11 is provided, wherein the integrated acoustic wave filter 11 has a working area 13 and an annular wall structure 15 located on the integrated acoustic wave filter 11 .

[0089] Specifically, in the embodiment of the present invention, the BAW filter 11 may further include a pad structure 16 , and the pad structure 16 is located inside the annular wall structure 15 .

[0090] S102: Figure 5 As shown, a package cover plate 12 is provided, and the package cover plate 12 is processed to form a groove area 14 .

[0091] Specifically, in the embodiment of the present invention, including but not limited to coating photoresist, exposing the area where the groove area 14 is to be formed through exposure, development, etc., then including but not limited to forming the groove area 14 through dry etching, and finally removing the photoresist.

[0092] S103: Figure 6 As shown, the packaging cover plate 12 is bonded to the bulk acoustic wave filter 11; after the bonding is completed, the groove area 14 faces one side of the bulk acoustic wave filter 11, and the annular wall structure 15 is located between the bulk acoustic wave filter 11 and the packaging cover plate 12; in a first direction X, the orthographic projection of the groove area 14 at least covers the orthographic projection of the working area 13; the first direction X is perpendicular to the plane where the bulk acoustic wave filter 11 is located; wherein the working area 13 and the groove area 14 are both located inside the annular wall structure 15.

[0093] Specifically, in the embodiment of the present invention, one possible way to bond the package cover plate 12 to the BAW filter 11 is:

[0094] The packaging cover plate 12 and the BAW filter 11 are bonded together by applying glue 21 .

[0095] Exemplarily, under the conditions of a temperature range of 130° C.-170° C. and a pressure range of 4000N-6000N, the package cover plate 12 is bonded to the BAW filter 11 by applying glue 21. Specifically, glue 21 is applied to the surface of the package cover plate 12, and a wafer-level bonding device is used for bonding.

[0096] like Figure 7As shown, the method for preparing the bulk acoustic wave filter packaging structure further includes:

[0097] The BAW filter 11 is processed to form a first through hole 17 penetrating the BAW filter 11 , wherein the first through hole 17 exposes a portion of the surface of the pad structure 16 .

[0098] Exemplarily, the BAW filter 11 is first thinned to a target thickness, for example, the BAW filter 11 is thinned to a thickness range of 90 μm-110 μm; then, including but not limited to coating a photoresist, exposing the area where the first through hole 17 is to be formed through exposure, development, etc.; then, including but not limited to forming the first through hole 17 through dry etching, and finally removing the photoresist.

[0099] like Figure 8 As shown, the method for preparing the bulk acoustic wave filter packaging structure further includes:

[0100] An RDL wiring structure 18 is formed, and the RDL wiring structure 18 is electrically connected to the pad structure 16 through the first through hole 17 .

[0101] Exemplarily, titanium and copper metals are first deposited on the surface of the BAW filter 11 facing away from the package cover 12, and then copper is plated on the surface of the BAW filter 11 using electroplating equipment. After that, including but not limited to coating photoresist, the position where the RDL lead structure 18 is to be formed is protected by exposure, development, etc., and finally, excess metal is etched away and the photoresist is removed to form the RDL lead structure 18.

[0102] like Fig. 9 As shown, the method for preparing the BAW filter packaging structure further includes:

[0103] A protective layer 19 is formed on the side of the BAW filter 11 away from the package cover plate 12; the protective layer 19 has a second through hole 22, and the second through hole 22 exposes a portion of the surface of the RDL lead structure 18. The protective layer 19 includes but is not limited to a polyimide layer, and its main function is to protect the RDL lead structure 18, buffer the stress generated during the packaging process, prevent overcurrent, etc., so as to improve the stability and reliability of the BAW filter packaging structure.

[0104] like Figure 1 As shown, the method for preparing the bulk acoustic wave filter packaging structure further includes:

[0105] A solder ball 20 is formed on a side of the BAW filter 11 away from the package cover plate 12 ; the solder ball 20 is electrically connected to the RDL lead structure 18 .

[0106] Exemplarily, first, on the side of the BAW filter 11 facing away from the packaging cover 12, the area where the solder ball 20 needs to be formed is exposed by methods including but not limited to coating photoresist, exposure, development, etc., and then, including but not limited to placing the solder ball 20 in the corresponding area by a ball planting machine, and then performing processes such as reflow and cleaning to form the solder ball 20.

[0107] Based on the above embodiment of the present invention, a radio frequency device is provided in another embodiment of the present invention. The radio frequency device includes the BAW filter packaging structure described in the above embodiment.

[0108] The above is a detailed introduction to a bulk acoustic wave filter packaging structure and a preparation method and a radio frequency device provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for general technicians in this field, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0109] It should be noted that each embodiment in this specification is described in a progressive manner, and each embodiment focuses on the differences from other embodiments, and the same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0110] It should also be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device that includes a series of elements is inherent to the elements, or also includes elements inherent to these processes, methods, articles or devices. In the absence of further restrictions, the elements defined by the sentence "including a..." do not exclude the presence of other identical elements in the process, method, article or device that includes the elements.

[0111] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one 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 invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bulk acoustic wave filter packaging structure, characterized in that: The BAW filter packaging structure comprises: A bulk acoustic wave filter and a packaging cover plate are arranged opposite to each other; the bulk acoustic wave filter has a working area, and the packaging cover plate includes a groove area arranged toward one side of the bulk acoustic wave filter; in a first direction, the orthographic projection of the groove area at least covers the orthographic projection of the working area; the first direction is perpendicular to the plane where the bulk acoustic wave filter is located; an annular wall structure located between the BAW filter and the packaging cover plate and on the BAW filter; Wherein, the working area and the groove area are both located inside the annular wall structure.

2. The BAW filter packaging structure according to claim 1, characterized in that: The material of the annular wall structure is metal material or inorganic material.

3. The BAW filter packaging structure according to claim 1, characterized in that: The width of the annular wall structure ranges from 2 μm to 5 μm; The thickness of the annular wall structure is in the range of 1 μm to 2 μm.

4. The BAW filter packaging structure according to claim 1, characterized in that: The depth of the groove region ranges from 5 μm to 15 μm.

5. The BAW filter packaging structure according to claim 1, characterized in that: The packaging cover plate is a Si cover plate.

6. The BAW filter packaging structure according to claim 1, characterized in that: The BAW filter packaging structure further includes: a pad structure located between the BAW filter and the package cover plate and on the BAW filter; The pad structure is located inside the annular wall structure.

7. The BAW filter packaging structure according to claim 6, characterized in that: The pad structure has a thickness ranging from 1 μm to 2 μm.

8. The BAW filter packaging structure according to claim 6, characterized in that: The BAW filter packaging structure further includes: A first through hole passes through the BAW filter, wherein the first through hole exposes a portion of a surface of the pad structure.

9. The BAW filter packaging structure according to claim 8, characterized in that: The BAW filter packaging structure further includes: An RDL lead structure is electrically connected to the pad structure through the first through hole.

10. The BAW filter packaging structure according to claim 9, characterized in that: The BAW filter packaging structure further includes: A protective layer is located on a side of the BAW filter away from the package cover plate; the protective layer has a second through hole, and the second through hole exposes a portion of the surface of the RDL lead structure.

11. The BAW filter packaging structure according to claim 10, characterized in that: The BAW filter packaging structure further includes: A solder ball is located on a side of the BAW filter away from the package cover plate; the solder ball is electrically connected to the RDL lead structure.

12. A method for preparing a bulk acoustic wave filter packaging structure, characterized in that: The preparation method of the bulk acoustic wave filter packaging structure comprises: Providing an integrated acoustic wave filter, the bulk acoustic wave filter having a working area and an annular wall structure located on the bulk acoustic wave filter; Providing a packaging cover plate, and processing the packaging cover plate to form a groove area; The packaging cover plate is bonded to the bulk acoustic wave filter; after the bonding is completed, the groove area faces one side of the bulk acoustic wave filter, and the annular wall structure is located between the bulk acoustic wave filter and the packaging cover plate; in a first direction, the orthographic projection of the groove area at least covers the orthographic projection of the working area; the first direction is perpendicular to the plane where the bulk acoustic wave filter is located; wherein the working area and the groove area are both located inside the annular wall structure.

13. The method for preparing a bulk acoustic wave filter packaging structure according to claim 12, characterized in that: The step of bonding the package cover plate to the bulk acoustic wave filter comprises: The packaging cover plate is bonded to the BAW filter by applying glue.

14. The method for preparing a bulk acoustic wave filter packaging structure according to claim 13, characterized in that: The method of bonding the package cover plate to the BAW filter by applying glue comprises: Under the conditions of a temperature range of 130° C.-170° C. and a pressure range of 4000N-6000N, the packaging cover plate and the BAW filter are bonded by applying glue.

15. The method for preparing a bulk acoustic wave filter packaging structure according to any one of claims 12 to 14, characterized in that: The BAW filter packaging structure further includes: a pad structure located between the BAW filter and the packaging cover plate and located on the BAW filter; the pad structure is located inside the annular wall structure; The method for preparing the BAW filter packaging structure further comprises: The BAW filter is processed to form a first through hole penetrating the BAW filter, wherein the first through hole exposes a portion of the surface of the pad structure.

16. The method for preparing a bulk acoustic wave filter packaging structure according to claim 15, characterized in that: The method for preparing the BAW filter packaging structure further comprises: An RDL wiring structure is formed, wherein the RDL wiring structure is electrically connected to the pad structure through the first through hole.

17. The method for preparing a bulk acoustic wave filter packaging structure according to claim 16, characterized in that: The method for preparing the BAW filter packaging structure further comprises: A protection layer is formed on a side of the BAW filter away from the package cover plate; the protection layer has a second through hole, and the second through hole exposes a portion of the surface of the RDL lead structure.

18. The method for preparing a bulk acoustic wave filter packaging structure according to claim 17, characterized in that: The method for preparing the BAW filter packaging structure further comprises: A solder ball is formed on a side of the BAW filter away from the package cover plate; the solder ball is electrically connected to the RDL lead structure.

19. A radio frequency device, characterized in that: The radio frequency device comprises the bulk acoustic wave filter packaging structure according to any one of claims 1 to 11.

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