Radio Frequency Filter and Its Preparation Method

Abstract

The present invention provides a radio frequency filter and a preparation method thereof. Among them, the preparation method of the radio frequency filter includes: forming a sealed outer wall and a support electrode on a substrate; forming a sacrificial layer on a carrier wafer, and forming a cavity-sealed outer shell and a bonding electrode on the sacrificial layer; bonding and connecting the sealed outer wall and the support electrode with the bonding electrode; removing the carrier wafer by etching the sacrificial layer. The present invention peels off the temporarily bonded carrier wafer by etching the sacrificial layer, thereby enabling the protective temporary carrier wafer to be removed without damage, enabling the carrier wafer to be reused, improving the utilization rate of the carrier wafer, and greatly reducing the packaging cost.

Description

Technical Field

[0001] The present invention relates to the technical field of filters, and particularly to a radio frequency filter and a preparation method thereof. Background Art

[0002] With the continuous development of 5G technology, the application and demand of radio frequency filters are continuously upgraded, and the performance index requirements for radio frequency filters are continuously improved. According to the transmission mode of acoustic waves in radio frequency filters, they are generally divided into: bulk acoustic wave filters and surface acoustic wave filters; among them, surface acoustic wave filters generally operate below 2.5G frequency, and bulk acoustic wave filters operate in the frequency range of 1.5G - 10G.

[0003] Whether it is a surface acoustic wave filter or a bulk acoustic wave filter, in order to maintain good radio frequency performance indicators, there are certain requirements for its working environment, and a relatively airtight cavity needs to be prepared to isolate the influence of external water vapor, particles, contamination, etc. on the device. The conventional methods generally include the following two: (1) First, prepare a protective substrate, which is usually silicon, glass, ceramic, metal shell, etc., and then isolate and protect the filter by means of wafer-level bonding, welding, adhesion, etc., and then process it through a series of complex processes such as deep hole etching, physical vapor deposition, and electroplating. After bonding, the carrier wafer is removed by grinding, with high cost and unable to meet the chip size requirements; the entire process flow is long, the process implementation difficulty is high, and the material cost is expensive; (2) Adopt the method of large-area film covering for the cavity. This method has low cost, but it will affect the device performance of devices that are sensitive to the degassing substances of film materials, restricting its application range. Summary of the Invention

[0004] (I) Technical Problems to be Solved

[0005] In view of the above problems, the main object of the present invention is to provide a radio frequency filter and a preparation method thereof, in order to at least partially solve at least one of the above-mentioned technical problems.

[0006] (II) Technical Solutions

[0007] According to one aspect of the present invention, there is provided a preparation method of a radio frequency filter, including:

[0008] Form a sealed outer wall and a support electrode on a substrate;

[0009] Form a sacrificial layer on a carrier wafer, and form a cavity sealing outer shell and a bonding electrode on the sacrificial layer;

[0010] Bond and connect the sealed outer wall and the support electrode with the bonding electrode;

[0011] Remove the carrier wafer by etching the sacrificial layer.

[0012] Further, after forming the sealed outer wall and the support electrodes on the substrate, it includes:

[0013] Preparing a sacrificial layer on the substrate formed with the sealed outer wall and the support electrodes;

[0014] Making the sealed outer wall and the support electrodes have the same height by chemical mechanical polishing;

[0015] Removing the sacrificial layer on the substrate.

[0016] Further, forming a sacrificial layer on the carrier wafer, and forming a cavity sealed housing and bonding electrodes on the sacrificial layer, includes:

[0017] Preparing a sacrificial layer on the carrier wafer;

[0018] Preparing a cavity sealed housing on the sacrificial layer and forming an opening;

[0019] Preparing bonding electrodes on the cavity sealed housing formed with the opening.

[0020] Further, bonding and connecting the sealed outer wall and the support electrodes with the bonding electrodes, includes:

[0021] Bonding and connecting the sealed outer wall and the support electrodes with the bonding electrodes by eutectic bonding, thermocompression bonding or co - bonding to form a sealed cavity.

[0022] Further, removing the carrier wafer by etching the sacrificial layer includes: etching the sacrificial layer by wet etching to separate the cavity sealed housing from the carrier wafer.

[0023] According to another aspect of the present disclosure, there is provided a radio frequency filter, including: a substrate, a sealed outer wall, support electrodes, bonding electrodes, a cavity sealed housing; wherein, the sealed outer wall and the support electrodes are located on the substrate, the cavity sealed housing is located on the bonding electrodes, and the sealed outer wall and the support electrodes are both bonded and connected with the bonding electrodes; the material of the cavity sealed housing is a dielectric and / or a metal.

[0024] Further, the materials of the sealed outer wall, the support electrodes and the bonding electrodes are copper, aluminum, tin, gold, germanium.

[0025] Further, the sealed outer wall is annular, protruding from the surface of the substrate, and a closed space is formed between the annular sealed outer wall, the substrate, the sealed housing and the bonding electrodes;

[0026] The support electrodes are columnar, protruding from the surface of the substrate, and are located inside the annular sealed outer wall and in the closed space.

[0027] Further, both the sealed outer wall and the support electrode have a boss structure, the bonding electrode has a notch structure, and the boss structure is disposed opposite to the notch structure.

[0028] Further, the boss structure includes a first part and a second part. The first part is connected to the surface of the substrate, the second part extends into the notch and is connected to the bonding electrode. The width of the second part is smaller than the width of the notch, and the width of the notch is smaller than the width of the first part.

[0029] (III) Advantageous Effects

[0030] As can be seen from the above technical solutions, the radio frequency filter and its manufacturing method of the present invention have at least one of the following advantageous effects:

[0031] (1) By etching the sacrificial layer, the present invention peels off the temporary bonding carrier, thus avoiding obtaining the cap by mechanical grinding, and greatly reducing the chip packaging thickness.

[0032] (2) Compared with the mechanical grinding method, by etching the sacrificial layer, the present invention peels off the temporary bonding carrier, thereby removing the protective temporary carrier without damage, enabling the carrier to be reused, improving the utilization rate of the carrier, and greatly reducing the packaging cost.

[0033] (3) The metal sealed outer wall, support electrode and bonding electrode of the present invention do not require precious metal materials, the manufacturing process flow is simple, and the cost is low.

[0034] (4) The sealing structure of the present invention uses a dielectric and a metal as a sealing housing, enhancing the structural strength, having a good heat dissipation effect, avoiding the use of glue materials, and making the sealing strength higher and the sealing performance better.

[0035] (5) The metal sealed outer wall and the support electrode of the present invention adopt a boss structure, which cooperates with the notch structure of the bonding electrode, reducing the device size and being conducive to miniaturization. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0037] In the drawings:

[0038] Figure 1 is a schematic structural diagram of the radio frequency filter of the present invention.

[0039] Figures 2 - 14 is a flow chart of the manufacturing method of the radio frequency filter of the present invention.

[0040] <Symbol Description>

[0041] 101 - Filter wafer silicon substrate, 104 - Filter wafer electrode, 105 - Piezoelectric film layer structure, 106 - Cavity, 203′(203) - Filter metal sealing outer wall, 52′(52) - Support electrode, 12 - Filter wafer sacrificial layer, 102 - Protective temporary silicon wafer, 14 - Protective temporary silicon wafer sacrificial layer, 415 - Cavity sealing housing, 53 - Cavity sealing housing bonding electrode, 412 - Cavity sealing housing passivation layer, 204 - Cavity sealing housing lead electrode, 205 - Cavity sealing housing lead electrode passivation layer, 57&59 - Cavity sealing housing external lead electrode, A - Boss structure, B - Notch structure, A1 - First part, A2 - Second part. Detailed implementation manners

[0042] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to specific embodiments and the accompanying drawings.

[0043] The present invention provides a method for manufacturing a radio frequency filter, including:

[0044] Forming a sealing outer wall and a support electrode on a substrate;

[0045] Forming a sacrificial layer on a carrier wafer, and forming a cavity sealing housing and a bonding electrode on the sacrificial layer;

[0046] Bonding and connecting the sealing outer wall and the support electrode with the bonding electrode;

[0047] Removing the carrier wafer by etching the sacrificial layer.

[0048] Compared with the mechanical grinding method, the present invention strips the temporary bonding carrier wafer by etching the sacrificial layer, thereby enabling the carrier wafer to be stripped without damage, allowing the carrier wafer to be reused, improving the utilization rate of the carrier wafer, greatly reducing the packaging cost, and greatly reducing the chip packaging thickness, which can meet the requirements of device miniaturization.

[0049] Optionally, for the method for manufacturing a radio frequency filter, after forming a sealing outer wall and a support electrode on a substrate and before bonding, it further includes:

[0050] Preparing a sacrificial layer on the substrate formed with a sealing outer wall and a support electrode;

[0051] Making the sealing outer wall and the support electrode have the same height by chemical mechanical polishing;

[0052] Removing the sacrificial layer on the substrate.

[0053] Thus, making the sealed outer wall and the support electrode have the same height can not only be applicable to thermocompression bonding but also eutectic bonding, while improving the sealing effect, which is beneficial to further improving the device performance.

[0054] Specifically, a sacrificial layer is formed on a carrier wafer, and a cavity-sealed housing and bonding electrodes are formed on the sacrificial layer, including:

[0055] Preparing a sacrificial layer on the carrier wafer;

[0056] Preparing a cavity-sealed housing on the sacrificial layer and forming an opening;

[0057] Preparing bonding electrodes on the cavity-sealed housing with an opening formed thereon.

[0058] Existing RF filters usually remove the carrier wafer by grinding. In the present invention, forming a sacrificial layer on the carrier wafer facilitates the non-destructive removal of the glass carrier wafer after bonding, thereby improving the reuse rate of the carrier wafer and reducing the cost.

[0059] The present invention also provides an RF filter, including: a substrate, a sealed outer wall, a support electrode, a bonding electrode, and a cavity-sealed housing; wherein, the sealed outer wall and the support electrode are located on the substrate, the cavity-sealed housing is located on the bonding electrode, and the sealed outer wall and the support electrode are bonded to the bonding electrode; the material of the cavity-sealed housing is a dielectric and / or metal. The materials of the sealed outer wall, the support electrode, and the bonding electrode are metals. Thus, the structural strength can be increased, heat dissipation of the device is facilitated, and the use of adhesive materials is avoided, resulting in higher sealing strength and better sealing performance.

[0060] Wherein, the carrier wafer is, for example, a protective temporary silicon-based wafer, the substrate is, for example, a wafer silicon substrate, and the substrate further includes a functional structure and a wafer electrode, and the functional structure is, for example, a piezoelectric structure.

[0061] Specifically, the sealed outer wall is annular and protrudes from the surface of the substrate, and a closed space is formed between the annular sealed outer wall, the substrate, the sealed housing, and the bonding electrode. The sealed housing is also called a cavity-sealed housing, that is, the housing that seals the cavity to form the closed space, and the sealed outer wall is the outer wall that seals the cavity to form the closed space.

[0062] The support electrode is columnar and protrudes from the surface of the substrate, and is located inside the annular sealed outer wall and in the closed space. The number of the support electrodes is, for example, four, and they are evenly arranged in the sealed space. Preferably, the minimum distance between the support electrode and the sealed outer wall is greater than or equal to 5 microns. The contact areas between the sealed outer wall and the bonding electrode, and between the support electrode and the bonding electrode are both greater than or equal to 20 microns.

[0063] Both the sealed outer wall and the support electrode have a boss structure, the bonding electrode has a notch structure, and the boss structure is disposed opposite to the notch structure.

[0064] The boss structure includes a first part and a second part. The first part is connected to the surface of the substrate and extends in a direction parallel to the surface of the substrate. The second part extends in a direction perpendicular to the surface of the substrate. The second part extends into the notch and is connected to the bonding electrode. The width of the second part is smaller than the width of the notch, and the width of the notch is smaller than the width of the first part. Thus, the size of the device can be further reduced.

[0065] In one embodiment, the present invention provides a radio frequency filter, which includes a radio frequency filter silicon-based wafer, a protective temporary carrier, and a bonded body thereof.

[0066] Wherein, the radio frequency filter wafer includes a filter functional area and an electrode area. The electrode area includes a metal sealed outer wall and a support electrode area. The protective temporary silicon-based carrier includes a cavity sealed outer shell and a sacrificial layer. The sacrificial layer is deposited on the surface of the protective temporary carrier. The cavity sealed outer shell includes a bonding electrode and a cavity sealed outer shell. The bonding electrode corresponds to the filter electrode area of the radio frequency filter wafer and is prepared on the cavity sealed outer shell. The cavity sealed outer shell is prepared on the surface of the sacrificial layer. The bonded body is prepared by wafer-level bonding of the radio frequency filter wafer and the protective temporary carrier. And by etching the sacrificial layer method, the separation of the temporary carrier and the cavity sealed outer shell is realized.

[0067] The protective temporary carrier can be made of materials such as silicon-based, III-V group, lithium carbonate, etc. The metal sealed outer wall and the support electrode can be made of materials such as copper, aluminum, tin, gold, germanium, etc. The bonding electrode of the cavity sealed outer shell can be made of materials such as copper, aluminum, tin, gold, germanium, etc. The sacrificial layer of the protective temporary silicon-based carrier can be a dielectric layer or a glue, such as silicon oxide, etc.

[0068] The wafer-level bonding method can be eutectic melting, hot pressing, and eutectic bonding.

[0069] The radio frequency filter of the present invention has high structural strength, good airtightness, and improves the heat dissipation efficiency due to the large-area use of metal.

[0070] In another embodiment, the present invention provides a method for manufacturing a radio frequency filter, which specifically includes:

[0071] S1. Prepare a metal sealed outer wall and a support electrode on the surface of the radio frequency filter silicon-based wafer by electroplating. If the heights of the metal sealed outer wall and the support electrode after electroplating meet the bonding requirements, there is no need to adopt the sacrificial layer deposition and chemical mechanical polishing methods, that is, the processes from S2 to S4 can be omitted;

[0072] S2. Prepare a sacrificial layer on the surface of the silicon-based wafer of the RF filter by chemical vapor deposition;

[0073] S3. Obtain electrodes with relatively consistent heights by chemical mechanical polishing;

[0074] S4. Remove the remaining sacrificial layer on the substrate by dry etching or wet etching;

[0075] S5. Prepare a sacrificial layer on the protective temporary carrier by chemical vapor deposition;

[0076] S6. Prepare a dielectric layer on the surface of the sacrificial layer of the protective temporary carrier by chemical vapor deposition to form a cavity sealing shell, and open the bonding electrode opening by photolithography etching; Further, if the structural strength of the single-layer dielectric layer is insufficient, the structural strength can be improved by increasing the thickness of the dielectric layer or using a multi-layer structure;

[0077] S7. Prepare bonding electrodes by photolithography and electroplating;

[0078] S8. Etch the sacrificial layer between the dicing lanes by photolithography and etching to reduce the etching time of the bonding sacrificial layer and lower the etching difficulty;

[0079] S9. Bond the silicon-based wafer of the RF filter and the protective temporary carrier together by wafer-level bonding to close the sealed cavity;

[0080] S10. Etch the protective sacrificial layer by dry or wet method to separate the protective temporary carrier from the cavity sealing shell;

[0081] S11. Prepare a passivation layer on the surface of the cavity sealing shell by chemical vapor deposition to isolate the metal sealing outer wall and avoid short circuit; Further, in step S11, the preparation of the passivation layer can cover the outer contour of the chip and the silicon-based wafer of the RF filter to achieve overall chip protection.

[0082] S12. Realize the transfer of the support electrode through the redistribution technology;

[0083] S13. Realize the external connection of the electrode through the bump flip-chip technology.

[0084] The present invention realizes the encapsulation of a radio frequency filter by etching the sacrificial layer of a protective carrier wafer to prepare a cavity-sealed housing. The preparation method has a simple process flow, can be compatible with semiconductor processes, and greatly reduces costs. Moreover, the sacrificial layer etching method is used to peel off the protective temporary carrier wafer (bonding carrier wafer), making the device packaging thickness thinner than that of traditional radio frequency filters. In addition, a sealing structure is formed by using metal or dielectric, and its sealing strength and airtightness are equivalent to those of traditional gold-gold bonding.

[0085] The following will Figures 1 - 14 introduce in detail an example of the structure and preparation method of the radio frequency filter of the present invention with reference to the attached

[0086] Please refer to Figures 1 - 14 As shown, the radio frequency filter mainly includes a filter wafer silicon substrate 101, a protective temporary silicon wafer 102, and its cavity-sealed lead packaging structure.

[0087] Specifically, wafer electrodes 104, a piezoelectric film layer structure 105, a metal sealing outer wall 203′, and a support electrode 52′ are respectively provided on the filter wafer silicon substrate 101; among them, the metal sealing outer wall 203 and the support electrode 52 can be prepared by electroplating, and the materials can be copper, aluminum, germanium, tin, gold, etc., and the height is between 5 and 20 microns.

[0088] The protective temporary silicon wafer 102 includes a sacrificial layer 14, a cavity-sealed housing 415, and a bonding electrode 53. Among them, the sacrificial layer 14 is prepared by chemical vapor deposition, and the material can be silicon oxide, and the thickness is greater than 1 micron. The cavity-sealed housing 415 is prepared by chemical vapor deposition, and the bonding electrode opening is opened by photolithography and etching. The material can be silicon nitride, silicon carbide, aluminum nitride, etc.; the thickness is more than 5 microns. The bonding electrode 53 is prepared by electroplating, and the materials are copper, aluminum, germanium, tin, gold, etc., and the height is between 5 and 40 microns.

[0089] Among them, the cavity-sealed housing 415 is the outer housing that seals the cavity 106 to form the closed space, and the metal sealing outer wall 203′ is the outer wall that seals the cavity 106 to form the closed space.

[0090] The sealed outer wall and the support electrode both have a boss structure A, the bonding electrode has a notch structure B, and the boss structure is arranged opposite to the notch structure. The boss structure includes a first part A1 and a second part A2. The first part is connected to the surface of the filter wafer silicon substrate 101 and extends along a direction parallel to the surface of the substrate. The second part extends along a direction perpendicular to the surface of the filter wafer silicon substrate 101. The second part extends into the notch and is connected to the bonding electrode 53. The width w2 of the second part is smaller than the width w3 of the notch, and the width w3 of the notch is smaller than the width w1 of the first part. In this example, the sealed outer wall and the support electrode have the same boss structure, but of course it is not limited to this.

[0091] The cavity-sealed lead structure includes a lead electrode 204 and a flip-chip electrode 57 / 59. The lead electrode is prepared by electroplating, and the material can be copper, with a thickness between 5 and 20 microns. The flip-chip electrode 57 / 59 is prepared by electroplating, and the material can be a copper-tin combination, with a thickness between 20 and 60 microns.

[0092] Figure 1 The preparation process of the shown radio frequency filter is as Figures 2 - 14 shown.

[0093] Step 1: As Figure 2 shown, provide a substrate 102 that forms an electrode region 104, a piezoelectric film layer structure region 105, a metal sealed outer wall 203, and a support electrode 52, or form an electrode region 104, a piezoelectric film layer structure region 105, a metal sealed outer wall 203, and a support electrode 52 on a radio frequency filter wafer 101. Among them, the metal sealed outer wall 203 and the support electrode 52 are prepared by electroplating, and the materials can be copper, aluminum, germanium, tin, gold, etc., and the height is preferably between 5 and 20 microns. It should be noted that if the heights of the metal sealed outer wall 203 and the support electrode 52 in Step 1 are the same and can meet the requirements of eutectic bonding, then the chemical mechanical polishing and sacrificial layer deposition in Steps 2 to 4 can be cancelled.

[0094] Among them, the surface of the electrode region 104 is flush with the surface of the substrate. The surface of the piezoelectric film layer structure region 105 protrudes from the surface of the substrate. The metal sealed outer wall 203 is integrally annular, and the support electrode is columnar. In this example, the number of support electrodes is four.

[0095] Step 2: As Figure 3As shown, a sacrificial layer 12 is prepared on the surface of the RF filter wafer 101 formed with an electrode region 104, a piezoelectric film layer structure region 105, a metal hermetic outer wall 203, and a support electrode 52 by chemical vapor deposition. The sacrificial layer material can be silicon oxide with a thickness greater than 1 micron. The support electrode 52 is opposite to the electrode region 104.

[0096] Step 3: As Figure 4 shown, the metal hermetic outer wall 203 and the support electrode 52 are exposed by chemical mechanical polishing, and a highly consistent metal hermetic outer wall 203' and support electrode 52' are obtained.

[0097] Step 4: As Figure 5 shown, the sacrificial layer 12 is removed by wet etching. If it is a thin film bulk acoustic resonator filter (FBAR), the resonator cavity needs to be released synchronously.

[0098] Among them, steps 2 to 4 are to make the height of the metal hermetic outer wall consistent with that of the support electrode to meet the higher bonding height consistency requirements and ensure the sealing of the device.

[0099] Step 5: As Figure 6 shown, a sacrificial layer 14 is prepared on the protective temporary silicon wafer 102 by chemical vapor deposition. The sacrificial layer 14 material is silicon oxide with a thickness greater than 1 micron.

[0100] Step 6: As Figure 7 shown, a cavity sealing housing 415 is prepared on the sacrificial layer 14 of the protective temporary silicon wafer 102 by chemical vapor deposition, and the bonding electrode 53 opening is opened by photolithography and etching (i.e., an opening is formed in the cavity sealing housing 415). The material of the cavity sealing housing 415 is silicon nitride with a thickness greater than 5 microns. Of course, the material of the cavity sealing housing can be replaced with metal, and its structure can be single-layer or multi-layer, which can be multi-layer dielectric layers, multi-layer metal layers, or a stacked structure of dielectric layers and metal layers, thus well meeting the requirements of the device's structural strength and thickness adjustment and improving the flexibility of device design.

[0101] Step 7: As Figure 8 shown, the bonding electrode 53 is prepared on the surface of the cavity sealing housing 415 by electroplating. The material is copper plus tin. The thickness of copper is greater than 5 microns, and the thickness of tin is about 2 - 5 microns ( Figure 8 the lower layer of the bonding electrode 53, i.e., the light-colored area, is copper, and the upper layer, i.e., the dark-colored area, is tin).

[0102] Step 8: The Figure 9As shown, the sacrificial layer 14 within the scribing lane (wafer edge) is etched away by means of photolithography and etching. If the sacrificial layer on the protective temporary silicon-based wafer is easily removable after bonding, step eight can be omitted.

[0103] Step Nine: As Figure 10 shown, the RF filter wafer 101 and the protective temporary silicon-based wafer 102 are wafer-level bonded by means of eutectic bonding to achieve eutectic bonding of the cavity sealing housing 415, the metal sealing outer wall 203', and the support electrode 52' to form a sealed cavity.

[0104] Step Ten: As Figure 11 shown, the sacrificial layer 14 is etched away by means of wet etching to separate the cavity sealing housing 415 from the protective temporary silicon-based wafer 102.

[0105] Step Eleven: As Figure 12 shown, a passivation layer 412 is prepared on the surface of the cavity sealing housing 415 by means of glue coating to isolate the metal sealing outer wall 203' and prevent short circuit; the material of the passivation layer 412 is glue, and the thickness is between 5 - 20 microns.

[0106] Step Twelve: As Figure 13 shown, the lead electrode 204 is prepared by means of re-wiring technology, the material is copper, and the thickness is between 5 - 20 microns; the lead electrode passivation layer 205 is prepared by means of glue coating, the material is glue, and the thickness is between 5 - 20 microns;

[0107] Step Thirteen: As Figure 14 shown, the external lead flip-chip electrodes 57 / 59 are prepared by means of electroplated bumps, the material is copper plus tin, and the height is between 20 - 60 microns.

[0108] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and does not limit the scope of use of the present invention.

[0109] So far, the present invention has been described in detail with reference to the accompanying drawings. Based on the above description, those skilled in the art should have a clear understanding of the present invention.

[0110] It should be noted that in the accompanying drawings or the text of the specification, the implementation manners not depicted or described are all forms known to those of ordinary skill in the art and have not been described in detail. In addition, the above definitions of each component are not limited to the specific structures, shapes, or manners mentioned in the embodiments, and those of ordinary skill in the art can make simple changes or substitutions thereto.

[0111] Of course, according to actual needs, the present invention may also include other parts, which are not elaborated herein as they have nothing to do with the innovative aspects of the present invention.

[0112] Similarly, it should be understood that, in order to streamline the present invention and assist in understanding one or more of the various inventive aspects, in the above description of the exemplary embodiments of the present invention, the various features of the present invention are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present invention should not be construed as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as reflected in the following claims, the inventive aspects lie in less than all the features of a single preceding embodiment of the invention. Thus, the claims following the detailed description are hereby expressly incorporated into the detailed description, where each claim stands on its own as a separate embodiment of the present invention.

[0113] Unless otherwise expressly stated, each feature of the invention in this specification (including the accompanying claims, abstract, and drawings) may be replaced by alternative features that serve the same, equivalent, or similar purpose.

[0114] Furthermore, the ordinal terms used in the specification and claims, such as "first", "second", "third", etc., are used to modify the corresponding elements, and do not themselves imply or represent any ordinal of the element, nor the order of one element with another element, or the order in the manufacturing method. The use of these ordinal terms is only to clearly distinguish one element with a certain name from another element with the same name.

[0115] In addition, in the drawings or the description of the specification, similar or identical parts are all denoted by the same reference numerals. The technical features in the various embodiments exemplified in the specification can be freely combined to form new solutions on the premise of no conflict. Additionally, each claim can be regarded as a separate embodiment alone, or the technical features in each claim can be combined to form a new embodiment. Moreover, in the drawings, the shape or thickness of the embodiment can be enlarged, and simplified or convenient markings can be used. Furthermore, the elements or implementation manners not depicted or described in the drawings are in forms known to those of ordinary skill in the art. Additionally, although this document may provide examples of parameters including specific values, it should be understood that the parameters need not exactly equal the corresponding values, but may approximate the corresponding values within an acceptable error tolerance or design constraint.

[0116] Unless there are technical obstacles or contradictions, the above various embodiments of the present invention can be freely combined to form additional embodiments, and these additional embodiments are all within the protection scope of the present invention.

[0117] Although the present invention has been described in conjunction with the accompanying drawings, the embodiments disclosed in the drawings are intended to exemplarily illustrate the preferred embodiments of the present invention and should not be construed as a limitation on the present invention. The dimensional ratios in the drawings are merely illustrative and should not be construed as a limitation on the present invention.

[0118] Although some embodiments of the general concept of the present invention have been shown and described, those of ordinary skill in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the general inventive concept. The scope of the present invention is defined by the claims and their equivalents.

[0119] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a radio frequency filter, characterized in that, Comprising: Forming a sealed outer wall and a support electrode on a substrate, wherein a wafer electrode is formed between the substrate and the support electrode; Forming a sacrificial layer on a carrier wafer, and forming a cavity sealed housing and a bonding electrode on the sacrificial layer; Bonding the sealed outer wall and the support electrode to the bonding electrode; Removing the carrier wafer by etching the sacrificial layer; Wherein, the sealed outer wall is annular, protruding from the surface of the substrate, and a closed space is formed among the annular sealed outer wall, the substrate, the sealed housing and the bonding electrode; The support electrode is cylindrical, protruding from the surface of the substrate, and located inside the annular sealed outer wall and in the closed space; Both the sealed outer wall and the support electrode have a boss structure, and the bonding electrode has a notch structure, and the boss structure and the notch structure are arranged oppositely; The boss structure includes a first part and a second part. The first part is connected to the surface of the substrate, and the second part extends into the notch to be connected to the bonding electrode. The width of the second part is smaller than the width of the notch, and the width of the notch is smaller than the width of the first part.

2. The manufacturing method of the radio frequency filter according to claim 1, characterized in that, After forming the sealed outer wall and the support electrode on the substrate, comprising: Preparing a sacrificial layer on the substrate formed with the sealed outer wall and the support electrode; Making the sealed outer wall and the support electrode have the same height by chemical mechanical polishing; Removing the sacrificial layer on the substrate.

3. The manufacturing method of the radio frequency filter according to claim 1, characterized in that, Forming a sacrificial layer on a carrier wafer, and forming a cavity sealed housing and a bonding electrode on the sacrificial layer, comprising: Preparing a sacrificial layer on the carrier wafer; Preparing a cavity sealed housing on the sacrificial layer and forming an opening; Preparing a bonding electrode on the cavity sealed housing formed with the opening.

4. The manufacturing method of the radio frequency filter according to claim 1, characterized in that, Bonding the sealed outer wall and the support electrode to the bonding electrode, comprising: Bonding the sealed outer wall and the support electrode to the bonding electrode by eutectic bonding, thermocompression bonding or co - eutectic bonding to form a sealed cavity.

5. The manufacturing method of the radio frequency filter according to claim 1, characterized in that, Removing the carrier wafer by etching the sacrificial layer includes: etching the sacrificial layer by wet etching to separate the cavity sealed housing from the carrier wafer.

6. A radio frequency filter, characterized in that, Comprising: A substrate, a sealed outer wall, a support electrode, a bonding electrode, a cavity sealed housing; wherein, the sealed outer wall and the support electrode are located on the substrate, the cavity sealed housing is located on the bonding electrode, and both the sealed outer wall and the support electrode are bonded to the bonding electrode; the material of the cavity sealed housing is a dielectric and / or a metal, and a wafer electrode is formed between the substrate and the support electrode; Wherein, the sealed outer wall is annular, protruding from the surface of the substrate, and a closed space is formed among the annular sealed outer wall, the substrate, the sealed housing and the bonding electrode; The support electrode is cylindrical, protruding from the surface of the substrate, and located inside the annular sealed outer wall and in the closed space; Both the sealed outer wall and the support electrode have a boss structure, and the bonding electrode has a notch structure, and the boss structure and the notch structure are arranged oppositely; The boss structure includes a first part and a second part. The first part is connected to the surface of the substrate, and the second part extends into the notch and is connected to the bonding electrode. The width of the second part is smaller than the width of the notch, and the width of the notch is smaller than the width of the first part.

7. The RF filter according to claim 6, wherein The materials of the sealing outer wall, the support electrode, and the bonding electrode are copper, aluminum, tin, gold, and germanium.

Images