RF Filters

Abstract

The present disclosure provides a radio frequency filter, which includes: a substrate, a supporting electrode and a thin film structure, wherein the supporting electrode is convexly arranged on the front surface of the substrate; the thin film structure is formed on the substrate with the supporting electrode spaced apart. The end surface of the top end of the supporting electrode is in sealing contact with the front surface of the thin film structure.

Description

Technical Field

[0001] The present disclosure relates to the technical field of filters, and in particular to a radio frequency filter. Background Art

[0002] With the continuous development of 5G technology, the application and demand of RF filters are constantly upgrading, and the performance requirements of RF filters are constantly increasing. According to the transmission method of sound waves, RF filters are usually 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 at 1.5G~10G frequency.

[0003] Whether it is a surface acoustic wave filter or a bulk acoustic wave filter, in order to maintain good RF performance indicators, there are certain requirements for its working environment. It is necessary to prepare a relatively closed cavity (i.e., a protective cavity) to isolate the device from the influence of external moisture, particles, contamination, etc. The conventional practice is to first prepare a protective substrate, which is usually silicon, glass, ceramic, metal shell, etc., and then use wafer-level bonding, welding and other processes to isolate and protect the filter, and then process it through a series of complex processes. For example, in order to realize the preparation of the protective cavity of the bulk acoustic wave (BAW) filter device, the following materials, processes and equipment can be used: 1) double-polished high-resistance silicon wafer as a protective substrate; 2) through-silicon via (TSV) and deep hole electrode filling technology are used for through-hole electrode processing; 3) gold is used as wafer bonding and electrode material; 4) expensive wafer bonding and physical vapor deposition equipment with lateral deposition capability are required.

[0004] Therefore, the use of the existing protective substrate determines that the entire preparation process of the RF filter is relatively long and the process is difficult to implement. At the same time, the application of the above materials, processes and equipment leads to the high cost of preparing a single BAW device, which directly affects the large-scale application and market competitiveness of the product. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In order to solve the technical problems that the entire preparation process of the above-mentioned RF filter is long and the process implementation is difficult, and at the same time, the application of materials, processes and equipment used in the existing preparation method leads to high single-chip preparation cost of BAW devices, the present disclosure provides a RF filter.

[0007] (II) Technical solution

[0008] The present disclosure provides a radio frequency filter, comprising: a substrate, a supporting electrode and a thin film structure, wherein the substrate,

[0009] A supporting electrode is convexly disposed on the front surface of the substrate;

[0010] Thin film structure, spaced supporting electrodes are formed on a substrate.

[0011] According to an embodiment of the present disclosure, the end surface of the top end of the support electrode is in sealing contact with the front surface of the thin film structure, and the support electrode includes: a first support electrode, a first seed layer, a plurality of second support electrodes and a plurality of second seed layers,

[0012] The first supporting electrode is protruding outwardly relative to the substrate at the edge of the front surface of the substrate, and the first supporting electrode surrounds the edge of the front surface of the substrate to form an annular closed structure;

[0013] Each of the plurality of second supporting electrodes is protruded outwardly relative to the substrate in a certain distribution at the middle of the front surface of the substrate, and the plurality of second supporting electrodes are surrounded by the first supporting electrode at the middle of the front surface of the substrate.

[0014] According to an embodiment of the present disclosure, the supporting electrode further includes:

[0015] The first seed layer is disposed between the first supporting electrode and the substrate;

[0016] Each second seed layer in the plurality of second seed layers is relatively arranged between each second supporting electrode in the plurality of second supporting electrodes and the substrate;

[0017] The material of the first seed layer and each of the plurality of second seed layers is titanium, tungsten, gold, copper or a combination of the above metals.

[0018] According to an embodiment of the present disclosure, the radio frequency filter further includes: a protection cavity,

[0019] The protection cavity is a cavity space between the first supporting electrode, the plurality of second supporting electrodes and the front surface of the substrate;

[0020] Among them, the distance between the front surface of the substrate and the end surface of the top of the first supporting electrode is j1, the distance between the front surface of the substrate and the end surface of the top of each second supporting electrode in the plurality of second supporting electrodes is j2, 10μm≤j1≤40μm, 10μm≤j2≤40μm; Δj=|j1-j2|, Δj≤10μm.

[0021] According to an embodiment of the present disclosure, the substrate includes: a resonant structure and a plurality of lower electrode layers,

[0022] The resonant structure is arranged on the front surface of the substrate corresponding to the protective cavity.

[0023] Each of the plurality of lower electrode layers corresponds to the lower surface of each of the plurality of second supporting electrodes and is concave inwardly on the front surface of the substrate, and the material of the lower electrode layer is copper, gold, molybdenum, aluminum or a combination of the above metals;

[0024] Wherein, the resonant structure at least comprises:

[0025] The piezoelectric layer is arranged on the front surface of the substrate corresponding to the protection cavity.

[0026] According to an embodiment of the present disclosure, the substrate further comprises: a plurality of spacer layers,

[0027] Each of the plurality of spacer layers corresponds to the lower surface of each of the plurality of lower electrode layers and is disposed between each of the plurality of lower electrode layers and the substrate.

[0028] The material of the spacer layer is titanium, tungsten, nickel, chromium or a combination of the above metals.

[0029] According to an embodiment of the present disclosure, the thin film structure includes: a film layer, a plurality of through holes, a plurality of lead electrodes and a plurality of back electrodes.

[0030] The membrane layer spacing support electrode is arranged on the substrate, and the end surface of the top end of the support electrode is in sealing contact with the front surface of the membrane layer, wherein the thickness of the membrane layer is m, 10μm≤m≤60μm;

[0031] Each through hole in the plurality of through holes is arranged corresponding to a middle position of an end surface of a top end of each second supporting electrode of the plurality of second supporting electrodes and penetrates the film layer;

[0032] Each of the plurality of lead electrodes is filled and arranged correspondingly to each of the plurality of through holes, the lower end of each of the plurality of lead electrodes is in contact with the end surface of the top end of each of the plurality of second supporting electrodes, the upper end of each of the plurality of lead electrodes is laid on the back surface of the film layer, and the inner surface of the upper end of each of the plurality of lead electrodes is in contact with the back surface of the film layer, wherein the thickness of the upper end of each of the plurality of lead electrodes located on the back surface of the film layer is y, 5μm≤m≤40μm; and

[0033] Each of the plurality of back electrodes is disposed on the outer surface of the upper end of each of the plurality of lead electrodes corresponding to each of the plurality of lead electrodes, and is correspondingly disposed directly above the first supporting electrode, wherein the height of the back electrode is b, 30 μm≤b≤150 μm;

[0034] Among them, the area of ​​the back surface of the film layer is s1, the distribution area of ​​the upper end of each of the multiple lead electrodes on the back surface of the film layer is s2, the number of the multiple lead electrodes is n, Δs=(n×s2) / s1, Δs≥0.2.

[0035] According to an embodiment of the present disclosure, the thin film structure further includes: a plurality of passivation layers and a plurality of passivation holes,

[0036] Each of the plurality of passivation layers corresponds to each of the plurality of lead electrodes and is covered on the outer surface of the upper end of each of the plurality of lead electrodes;

[0037] Each of the plurality of passivation holes corresponds to each of the plurality of back electrodes and is opened on each of the plurality of passivation layers.

[0038] According to an embodiment of the present disclosure, the membrane structure further comprises: a plurality of anchoring openings and a plurality of anchoring portions,

[0039] A plurality of anchor openings are correspondingly arranged above the first supporting electrode along the edge of the film layer, and the projection size of the anchor openings on the back surface of the film layer is length c and width k, where c≥40μm and k≥10μm;

[0040] Each of the plurality of anchoring portions is correspondingly disposed in each of the plurality of anchoring openings, and a thickness of the anchoring portion is d, 5 μm≤d≤40 μm.

[0041] According to an embodiment of the present disclosure, each of the plurality of anchoring portions comprises: an anchoring end and a fixing end, the anchoring end being correspondingly disposed in the anchoring opening;

[0042] The fixed end is correspondingly arranged on the back surface of the membrane layer, wherein the anchor end and the top end are connected to each other and are integrally formed.

[0043] According to an embodiment of the present disclosure, the supporting electrode further includes: a first sealing structure and a plurality of second sealing structures,

[0044] The first sealing structure is arranged on the end surface of the top end of the first supporting electrode;

[0045] Each of the plurality of second sealing structures corresponds to each of the plurality of second supporting electrodes and is disposed on an end surface of a top end of each of the plurality of second supporting electrodes;

[0046] The first sealing structure and each of the plurality of second sealing structures include a plurality of correspondingly arranged protruding portions or recessed portions, the height of the protruding portion is t, the depth of the recessed portion is a, t≥1 μm, a≥1 μm.

[0047] (III) Beneficial effects

[0048] The present disclosure proposes a radio frequency filter, which includes: a substrate, a supporting electrode and a thin film structure, wherein the supporting electrode is convexly arranged on the front surface of the substrate; and the thin film structure is formed on the substrate with the supporting electrode spaced apart. The end face of the top of the supporting electrode is in sealing contact with the front surface of the thin film structure. The present disclosure overcomes the technical prejudice in the field in terms of structure, and replaces the traditional protective wafer substrate with a thin film structure, so that the packaging of the radio frequency filter can achieve effective packaging of the device sealing cavity through a simple coating (corresponding to the film layer of the present disclosure), and the preparation process is greatly shortened, the production efficiency is improved, and the process is simplified; at the same time, the use of gold materials is avoided, which greatly reduces the device cost and improves the competitiveness of the device; in addition, in the device structure of the present disclosure, the distribution area of ​​the lead electrode on the back surface of the film layer can be unexpectedly controlled, which can further improve the heat dissipation efficiency of the device; more importantly, unexpected technical effects have been achieved: the processing cycle of the packaged product is shortened by more than half, which can be said to be a milestone in the history of research and development of radio frequency filter devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1A is a schematic internal perspective view of a radio frequency filter not covered with a thin film structure according to an embodiment of the present disclosure;

[0050] Figure 1B According to an embodiment of the present disclosure, Figure 1A A three-dimensional schematic diagram of the appearance of the radio frequency filter covered with a film layer;

[0051] Figure 1C According to an embodiment of the present disclosure, Figure 1B A three-dimensional schematic diagram of the appearance of a radio frequency filter having an anchoring portion and a lead electrode;

[0052] Figure 2A According to an embodiment of the present disclosure, Figure 1C A schematic cross-sectional view of the structure of the radio frequency filter with a back electrode taken along the BB' section;

[0053] Figure 2B According to an embodiment of the present disclosure, Figure 1C A schematic diagram of the cross-section structure of the radio frequency filter at the AA' cut line;

[0054] Figure 3 According to an embodiment of the present disclosure, Figure 2A and Figure 2B Schematic diagram of the preparation process of the RF filter;

[0055] Figure 4 is a schematic diagram of a preparation process of a radio frequency filter according to an embodiment of the present disclosure;

[0056] Figure 5Ais a structural schematic diagram of a preparation process stage of a radio frequency filter according to an embodiment of the present disclosure;

[0057] Figure 5B is another structural schematic diagram of a preparation process stage of a radio frequency filter according to an embodiment of the present disclosure;

[0058] Figure 5C is another structural schematic diagram of a stage of a preparation process of a radio frequency filter according to an embodiment of the present disclosure;

[0059] Figure 5D is another structural schematic diagram of a preparation process stage of a radio frequency filter according to an embodiment of the present disclosure;

[0060] Figure 6 is another schematic diagram of a preparation process of a radio frequency filter according to an embodiment of the present disclosure;

[0061] Fig. 7A is a structural schematic diagram of another stage of the preparation process of a radio frequency filter according to an embodiment of the present disclosure;

[0062] Figure 7B is another corresponding step of another preparation process stage of the radio frequency filter according to one embodiment of the present disclosure Figure 1B Schematic diagram of the structure of the AA' tangent line;

[0063] Figure 8 is another schematic diagram of a preparation process of a radio frequency filter according to an embodiment of the present disclosure;

[0064] Fig.9A is a structural schematic diagram of another stage of the preparation process of a radio frequency filter according to an embodiment of the present disclosure;

[0065] Fig. 9B is another structural schematic diagram of another stage of the preparation process of the radio frequency filter according to an embodiment of the present disclosure;

[0066] Fig. 9C It is another structural schematic diagram of another stage of the preparation process of the radio frequency filter according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0067] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0068] One aspect of the present disclosure provides a radio frequency filter, such as Figures 1A-1C ,as well as Figure 2A-2B As shown, it includes: a substrate 110, a supporting electrode 200 and a thin film structure 300,

[0069] The support electrode 200 is protruded outwardly from the substrate 110 and disposed on the front surface of the substrate 110;

[0070] The thin film structure 300 is formed on the substrate 110 with the support electrode 200 interposed therebetween, and the end surface of the top end of the support electrode 200 is in sealing contact with the front surface of the thin film structure 300 .

[0071] According to an embodiment of the present disclosure, for the RF filter of the present disclosure, the substrate 110 may be the whole or part of the wafer substrate. Specifically, for example, when the substrate 110 is the whole of the wafer substrate, the RF filter of the present disclosure may be a separate RF filter structure. When the substrate 110 is a part of the wafer substrate, the RF filter of the present disclosure may be a separate device structure in the array structure of the RF filter formed by the wafer substrate. Among them, the wafer substrate may be a wafer-level substrate with an area size of 4 inches, 6 inches, or 8 inches. The wafer-level substrate material may be silicon, glass, or a III-V semiconductor material, and is used as a matching substrate for the thin film structure 300 of the present disclosure. The substrate 110 may also be used to provide a substrate for forming a support electrode, and at the same time form a protective space for the corresponding resonant structure of the RF filter.

[0072] In order to effectively seal the substrate 110 and protect the resonant structure of the radio frequency filter, the present disclosure provides a support electrode 200 formed on the front surface of the substrate 110. The support electrode 200 is protruded outwardly from the substrate 110 on the front surface of the substrate 110 and can be integrally formed with the substrate 110. According to the embodiment of the present disclosure, the "front surface" and the subsequent "back surface" are only defined relative to the location of the resonant structure, that is, the surface where the resonant structure is located or the surface facing the resonant structure is referred to as the "front surface" in the present disclosure, and vice versa, it is referred to as the "back surface".

[0073] According to the embodiments of the present disclosure, due to the adoption of the thin film structure 300, the supporting electrode 200 material can be made of copper, or copper-like materials, copper-like alloy materials, etc., which greatly reduces the cost. In the embodiments of the fundamental disclosure, since the resistivity of copper, copper-like materials or copper-like alloy materials is lower than that of gold, it is beneficial to reduce the insertion loss of the device, and is beneficial to the diffusion of metal atoms under high temperature and high pressure, making the contact interface more blurred. Even relative to gold materials, the electrode material contact of the present disclosure achieves better bonding strength than gold material contact, as well as better resonance effect and sealing strength. Copper-like materials or copper-like alloy materials refer to materials with similar properties to copper itself, such as similar resistivity.

[0074] The thin film structure 300 has at least one film layer, which is directly attached to the substrate 110 having the support electrode 200 through a coating process. The support electrode is used to support the thin film structure 300, so as to form a protection space or a resonance space of the resonance structure between the thin film structure 300 and the substrate 110. In order to further effectively seal the device, the present disclosure can set a sealing structure on the end surface of the top end of the support electrode for contact sealing with the front surface of the film layer of the thin film structure 300.

[0075] The present invention structurally overcomes the technical prejudice in the art of "using a thin film structure 300 to replace the traditional protective wafer substrate", and replaces the traditional protective wafer substrate with a film layer, so that the packaging of the radio frequency filter can achieve effective packaging of the device sealing cavity through a simple coating (corresponding to the film layer of the present invention), and the preparation process is greatly shortened, the production efficiency is improved, and the process is simplified; at the same time, the use of gold materials is avoided, the device cost is greatly reduced, and the device competitiveness is improved; more importantly, an unexpected technical effect is achieved: the processing cycle of the packaged product is shortened by more than half, which can be said to be a milestone in the history of radio frequency filter device research and development.

[0076] To better illustrate the structure of the RF filter, refer to Figures 1A-1C ,as well as Figure 2A-2B The radio frequency filter structure of the present disclosure is described in detail. Here, those skilled in the art should understand that the relevant technical details mentioned in the "specific implementation" of the present disclosure are by no means limiting the protection scope of the present disclosure.

[0077] According to the embodiments of the present disclosure, Figure 1A ,as well as Figure 2A-2B As shown, the support electrode 200 includes: a first support electrode 210, a first seed layer, a plurality of second support electrodes 220 and a plurality of second seed layers. The first support electrode 210 is protruding outwardly relative to the substrate 110 at the edge of the front surface of the substrate 110, and the first support electrode forms an annular closed structure around the edge of the front surface of the substrate 110. The first support electrode 210 is used to provide edge support for the device structure of the thin film structure 300. The first support electrode 210 can be formed of copper, or copper-like materials, copper-like alloy materials, etc., to reduce material costs.

[0078] According to the embodiments of the present disclosure, Figure 1A ,as well as Figure 2A-2B As shown, the first seed layer is disposed between the first support electrode 210 and the substrate 110; the first seed layer is used to provide a transition layer between the first support electrode 210 and the substrate 110 to help increase the adhesion between the metal layers between the lower surface of the first support electrode 210 and the front surface of the substrate 110, so as to improve the diffusion capacity of metal atoms on the interface contact.

[0079] According to the embodiments of the present disclosure, Figure 1A ,as well as Figure 2A-2B As shown, each of the plurality of second support electrodes 220 is protruded outwardly relative to the substrate 110 in a certain distribution at the middle of the front surface of the substrate 110, and the plurality of second support electrodes 220 are surrounded by the first support electrode 210 at the middle of the front surface of the substrate 110. The certain distribution can be a uniform distribution on the front surface of the substrate 110 and in the space surrounded by the first support electrode 210, so as to effectively support the film layer 310 and improve the strength of the device structure. The second support electrode 220 is used to provide the thin film structure 300 with a central support function for the device structure, and the second support electrode 220 can be formed of copper, or a copper-like material, a copper-like alloy material, etc., to reduce material costs.

[0080] According to the embodiments of the present disclosure, Figure 1A ,as well as Figure 2A-2B As shown, each of the plurality of second seed layers is relatively arranged between each of the plurality of second support electrodes 220 and the substrate 110; the second seed layer is used to provide a transition layer between the second support electrode 220 and the substrate 110, so as to help increase the adhesion between the metal layers between the lower surface of the second support electrode 220 and the front surface of the substrate 110, so as to improve the diffusion capacity of metal atoms on the interface contact.

[0081] According to an embodiment of the present disclosure, the material of the first seed layer and each of the plurality of second seed layers is titanium, tungsten, gold, copper or a combination of the above metals, such as titanium tungsten plus copper alloy or titanium tungsten plus gold alloy.

[0082] According to the embodiments of the present disclosure, Figure 1A ,as well as Figure 2A-2B As shown, the radio frequency filter further includes: a protection cavity 420. The protection cavity 130 is the above-mentioned protection space, which is used to provide a protection space for the resonant structure arranged on the substrate 110, and can also be used to provide a resonant action space for the resonant structure.

[0083] According to the embodiments of the present disclosure, Figure 1A ,as well as Figure 2A-2B As shown, the protection cavity 420 is the cavity space between the first support electrode 210, the plurality of second support electrodes 220 and the front surface of the substrate 110; the shape of the protection cavity 420 can be set accordingly according to the cooperation of the first support electrode 210 and the plurality of second support electrodes 220, and is not limited in the present disclosure. In addition, the main space of the protection cavity 420 (which can be understood as the space corresponding to the resonant structure) needs to be slightly larger than the size of the corresponding resonant structure.

[0084] According to the embodiments of the present disclosure, Figure 1A ,as well as Figure 2A-2B As shown, the distance between the front surface of the substrate 110 and the end surface of the top of the first support electrode 210 is j1, and the distance between the front surface of the substrate 110 and the end surface of each of the second support electrodes 220 in the plurality of second support electrodes 220 is j2, 10μm≤j1≤40μm, 10μm≤j2≤40μm; Δj=|j1-j2|, Δj≤10μm. The distance j1 can be understood as the height of the first support electrode 210, and the distance j2 can be understood as the height of the second support electrode 220, which together determine the depth of the protection cavity 420 relative to the device structure. According to the embodiment of the present disclosure, in an ideal state, the height j1 of the first support electrode 210 and the height j2 of the second support electrode 220 should be equal, that is, Δj=0. Due to the differences in the preparation process (e.g., electroplating process) and the formation position (middle or edge) of the first support electrode 210 and the second support electrode 220 of the support electrode 200, the greater the overall height of the support electrode 200, the greater the Δj. The design of Δj≤10 μm is beneficial for the supporting electrode 200 to better support the film layer 310 of the thin film structure 300 after lamination, thereby preventing the film layer 310 from deforming and making the structure smoother.

[0085] According to the embodiments of the present disclosure, Figure 1A ,as well as Figure 2A As shown, the substrate 110 includes: a resonant structure and a plurality of lower electrode layers 120 . The resonant structure is arranged on the front surface of the substrate 110 corresponding to the protection cavity 420 to generate a resonant effect of the device.

[0086] According to the embodiments of the present disclosure, Figure 1A ,as well as Figure 2A As shown, each lower electrode layer 120 in the plurality of lower electrode layers 120 corresponds to the lower surface of each second supporting electrode 220 in the plurality of second supporting electrodes 220 and is concave in the front surface of the substrate 110. The material of the lower electrode layer 120 is copper, gold, molybdenum, aluminum or a combination of the above metals. The resonant structure on the substrate 110 can be electrically connected to the second supporting electrode 220 through the lower electrode layer 120, and the second supporting electrode 220 can also play a role in electrical connection with the lower electrode layer 120.

[0087] According to the embodiments of the present disclosure, Figure 1A ,as well as Figure 2A-2BAs shown, the resonant structure at least includes: a piezoelectric layer 130, which is arranged on the front surface of the substrate 110 corresponding to the protective cavity 420, and is used to play a certain resonant function to help achieve the resonance effect. At the same time, according to an embodiment of the present disclosure, the resonant structure may also include a resonant cavity, which may be a concave space located below the piezoelectric layer and concave on the front surface of the substrate 110. The piezoelectric layer may also be used to close the resonant cavity.

[0088] According to the embodiments of the present disclosure, Figure 1A-Figure 2B As shown, the substrate 110 further includes: a plurality of spacer layers, each of the plurality of spacer layers corresponds to the lower surface of each of the plurality of lower electrode layers 120, and is disposed between each of the plurality of lower electrode layers 120 and the substrate 110, and the spacer layer is used to provide a transition layer between the lower electrode layer 120 and the substrate 110, so as to help increase the adhesion between the metal layers between the outer surface of the lower electrode layer 120 and the substrate 110, so as to improve the diffusion capacity of metal atoms on the interface contact. According to an embodiment of the present disclosure, the material of the spacer layer is titanium, tungsten, nickel, chromium, or a combination of the above metals.

[0089] According to the embodiments of the present disclosure, Figure 1B-Figure 1C , Figure 2A As shown, the thin film structure includes: a film layer 310, a plurality of through holes 410, a plurality of lead electrodes 320 and a plurality of back electrodes 340, wherein the film layer 310 is arranged on the substrate 110 with the support electrode 200 spaced apart, and the end surface of the top of the support electrode 200 is in sealing contact with the front surface of the film layer 310. The thickness of the film layer is m, 10μm≤m≤60μm. The film layer 310 is the main structure of the thin film structure 300, and can be a dry film-type film. By performing a curing process on it, it can replace the traditional high temperature and high pressure bonding scheme to achieve device sealing. The film thickness of the film layer 310 will change to a certain extent before and after curing. Specifically, the thickness m of the film layer 310 after curing can be 20%-50% of the thickness m' before curing. In addition, the film layer 310 can be all or part of the wafer-level coating structure.

[0090] Therefore, the present disclosure adopts the film layer 310 to creatively replace the traditional wafer substrate as a protective layer, and at the same time realizes the device packaging process between the film layer 310 and the substrate 110, which is lower in cost and easier to process. It is the first in this field. In terms of structure, it overcomes the technical prejudice of "thin film layer as a protective layer" in this field, and replaces the traditional protective wafer substrate 110 with the thin film structure 300, so that the packaging of the RF filter can achieve effective packaging of the device sealing cavity through simple coating, and the preparation process is greatly shortened, the production efficiency is improved, and the process is simplified; at the same time, the use of gold materials is avoided, which greatly reduces the cost of the device and improves the competitiveness of the device; more importantly, it has achieved unexpected technical effects: the processing cycle of the packaged product is shortened by more than half, and deep silicon etching, deep hole sputtering, high temperature and high pressure bonding and other processes and corresponding equipment are no longer required, which greatly improves the preparation efficiency, saves preparation time and preparation cost, and the packaging production cost is greatly reduced. It can be said to be a milestone in the history of RF filter device research and development.

[0091] According to the embodiments of the present disclosure, Figure 1B-Figure 1C , Figure 2A As shown, each through hole 410 of the plurality of through holes 410 is arranged corresponding to the middle position of the end surface of the top end of each second supporting electrode 220 of the plurality of second supporting electrodes 220, and is penetrated through the film layer 310; the through hole 410 is used to provide a certain filling space and a fixed position for the lead electrode 320, which is conducive to a more regular and controllable distribution of the lead electrode 320 on the back surface of the film layer 310.

[0092] According to the embodiments of the present disclosure, Figure 1B-Figure 1C , Figure 2A As shown, each of the plurality of lead electrodes 320 is filled and arranged correspondingly to each of the plurality of through holes 410, the lower end of each of the plurality of lead electrodes 320 is in contact with the end surface of the top end of each of the plurality of second supporting electrodes 220, the upper end of each of the plurality of lead electrodes 320 is laid on the back surface of the film layer 310, and the inner surface of the upper end of each of the plurality of lead electrodes 320 is in contact with the back surface of the film layer 310, wherein the thickness of the upper end of each of the plurality of lead electrodes 320 located on the back surface of the film layer 310 is y, 5μm≤m≤40μm. The lower end portion of the lead electrode 320 is filled in the through hole 410, and the lower surface of the lower end portion of the lead electrode 320 is in sealing contact with the top end surface of the second support electrode 220. When the lower surface of the second support electrode 220 is electrically connected to the lower electrode layer 120 on the substrate 110, the lead electrode 320 is used to connect the lower electrode layer of the device to the outside.

[0093] According to the embodiments of the present disclosure, Figure 1B-Figure 1C , Figure 2A As shown, the upper end portion of the lead electrode 320 is laid flat on the back surface of the film layer 310, and is preferentially laid on the back surface area of ​​the corresponding film layer 310 between the second support electrode 220 and the first support electrode 210. The area of ​​the back surface of the film layer 310 is s1, the distribution area of ​​the upper end portion of each of the plurality of lead electrodes 320 on the back surface of the film layer 310 is s2, the number of the plurality of lead electrodes 320 distributed on the back surface of the film layer 310 is n, Δs=(n×s2) / s1, Δs≥0.2. The closer the value of Δs is to 1, the larger the coverage area of ​​the upper end portion of the lead electrode 320 on the back surface of the film layer 310, and the lead electrode 320 can also be used to improve the structural strength of the film layer 310 and increase the overall heat dissipation efficiency of the device. The material of the lead electrode 320 can be a metal such as copper. In the device structure disclosed in the present invention, the distribution area of ​​the lead electrode on the back surface of the film layer can be unexpectedly controlled, which can further improve the heat dissipation efficiency of the device.

[0094] According to the embodiments of the present disclosure, Figure 1B-Figure 1C , Figure 2A As shown, each of the plurality of back electrodes 340 is disposed on the outer surface of the upper end of each of the plurality of lead electrodes 320 corresponding to each of the lead electrodes 320, and is correspondingly disposed directly above the first support electrode 210. The first support electrode 210 can be used to simultaneously support the film layer 310 and the back electrode 340 on its back surface. The height of the back electrode 340 is b, 30μm≤b≤150μm, the lower surface of the back electrode 340 is connected to the outer surface of the lead electrode 320, and the back electrode 340 can be used to realize the electrical connection between the device structure and the outside.

[0095] According to the embodiments of the present disclosure, Figure 2A As shown, the thin film structure 300 further includes: a plurality of passivation layers 330 and a plurality of passivation holes 430, each of the plurality of passivation layers 330 corresponds to each of the plurality of lead electrodes 320 and is covered on the outer surface of the upper end of each of the plurality of lead electrodes 320. The passivation layer 330 can protect the lead electrode 320 (for example, from damage in subsequent processes) to increase device reliability, and the passivation layer 330 needs to be able to completely cover the lead electrode 320; the material of the passivation layer 330 can be a dielectric material or a colloid material.

[0096] According to the embodiments of the present disclosure, Figure 2AAs shown, each of the plurality of passivation holes 430 corresponds to each of the plurality of back electrodes 340 and is opened on each of the plurality of passivation layers 330. The passivation holes 430 are used to open the passivation layer 330 and provide a space for the back electrode 340 to be formed on the outer surface of the upper end portion of the lead electrode 320, so that the back electrode 340 can be electrically connected to the lead electrode 320.

[0097] According to an embodiment of the present disclosure, according to an embodiment of the present disclosure, as Figure 1B-Figure 1C , Figure 2B As shown, the thin film structure 300 further includes: a plurality of anchor openings 440 and a plurality of anchor portions 350, wherein the plurality of anchor openings 440 are correspondingly arranged above the first supporting electrode 210 along the edge of the film layer 310, and the projection size of the anchor openings 440 on the back surface of the film layer 310 is length c, width k, c ≥ 40 μm, k ≥ 10 μm, as shown in FIG. Figure 1B As shown in the figure, the larger the c and k values ​​are, the larger the contact area between the anchoring portion 350 and the film layer 310 will be determined by the anchoring opening 440, so that the anchoring opening 440 is used to provide an anchoring position for the anchoring portion 350, so as to better seal the film layer 310 on the substrate 110. The bottom surface of the anchoring opening 440 is the upper surface of the first supporting electrode 210, that is, the thickness of the film layer 310 is the height of the anchoring opening 440. Among them, the c and k values ​​can be set according to the size of the first supporting electrode 210.

[0098] According to an embodiment of the present disclosure, according to an embodiment of the present disclosure, as Figure 1B-Figure 1C , Figure 2B As shown, each of the plurality of anchoring portions 350 is correspondingly disposed in each of the plurality of anchoring openings 440, and the thickness of the anchoring portion 350 is d, 5μm≤d≤40μm. The material of the anchoring portion 350 may be metal, so as to improve the strength of the film layer 310, and at the same time to enhance the sealing between the film layer 310 and the first supporting electrode 210. After the curing process, the film layer can achieve a certain strength and corrosion resistance with the help of the anchoring portion 350, so as to further enhance the reliability and stability of the device, and at the same time increase the strength of the device and extend the life of the device.

[0099] According to an embodiment of the present disclosure, according to an embodiment of the present disclosure, as Figure 1B-Figure 1C , Figure 2BAs shown, each anchoring portion 350 of the plurality of anchoring portions 350 may be an L-shaped design, including: an anchoring end at the upper end of the anchoring portion 350 and a fixed end at the lower end of the anchoring portion 350. The L-shaped design is more conducive to the anchoring portion 350 to achieve the sealing effect and strength enhancement benefits brought by anchoring. Among them, the anchoring end and the top end are connected to each other and are integrally formed to form the anchoring portion 350. According to an embodiment of the present disclosure, the anchoring end is correspondingly arranged in the anchoring opening 440; its thickness d may be the thickness of the anchoring end of the anchoring portion 350 anchored at the edge of the back surface of the film layer 310, and the anchoring end is used to provide a top-down anchoring force to the back surface of the film layer 310 to help the anchoring effect. According to an embodiment of the present disclosure, the fixed end is correspondingly arranged on the back surface of the film layer, and its thickness d may be the width of the fixed end of the anchoring portion 350 anchored in the anchoring opening on the side surface of the film layer 310 and the upper surface of the first supporting electrode 210, which is equivalent to the above-mentioned k value. The top end is used to provide an anchoring force from bottom to top and from outside to inside between the side surface of the membrane layer 310 and the first supporting electrode layer 210 to help achieve an anchoring effect.

[0100] According to the embodiments of the present disclosure, Figure 2A As shown, the support electrode 200 also includes a sealing structure, which is used to form a sealed contact between the front surface of the film layer 310 and the sealing structure when the film layer 310 is coated and before the curing process is performed (at this time, the front surface of the film layer 310 has a certain adhesion force to facilitate sealing in cooperation with the sealing structure). After the curing process, the front surface of the film layer 310 will complete the sealing of the device structure through the sealing structure.

[0101] According to the embodiments of the present disclosure, Figure 2A As shown, the sealing structure includes: a first sealing structure and a plurality of second sealing structures, wherein the first sealing structure is arranged on the end surface of the top end of the first supporting electrode 210; and is used for sealing between the first supporting electrode 210 and the front surface of the film layer 310, so as to realize the peripheral packaging of the device. Each of the plurality of second sealing structures corresponds to each of the plurality of second supporting electrodes, and is arranged on the end surface of the top end of each of the plurality of second supporting electrodes; and is used for sealing between the plurality of second supporting electrodes 220 and the front surface of the film layer 310, so as to realize the internal packaging of the device.

[0102] According to the embodiments of the present disclosure, Figure 2A As shown, the first sealing structure and each of the plurality of second sealing structures include a plurality of corresponding protrusions or recesses, the height of the protrusion is t, the depth of the recess is a, t≥1μm, a≥1μm. The design of the protrusions or recesses will be more conducive to the fixation (for example, to prevent slippage, dislocation, etc.), connection and sealing between the first sealing structure and the second sealing structure and the front surface of the film layer 310 during the lamination-curing process of the film layer 310.

[0103] Another aspect of the present disclosure provides a preparation method, such as Figure 3 As shown, the method for preparing the above-mentioned radio frequency filter includes:

[0104] S310 : forming a resonant structure on the front surface of the substrate 110 ; specifically, a piezoelectric layer 130 , a lower electrode layer 120 , etc. of the resonant structure may be formed on the front surface of the substrate 110 .

[0105] S320: forming a support electrode 200 on the front surface of the substrate 110 based on the resonant structure; specifically, a resonant structure protection cavity based on the support electrode 200 may be formed on the front surface of the substrate 110. The support electrode 200 may be prepared by electroplating on the front surface of the substrate 110 according to a mask pattern to enhance the contact strength between the support electrode 200 and the front surface of the substrate 110.

[0106] S330: forming a thin film structure 300 with the support electrode 200 as an interval on the substrate 110, and the end surface of the top of the support electrode 200 is in sealing contact with the front surface of the thin film structure 300. Specifically, the film layer 310 of the thin film structure 300 can be fixedly sealed on the end surface of the top of the support electrode 200 by a lamination-curing process to achieve device packaging.

[0107] To facilitate understanding by those skilled in the art, the following description of the specific implementation methods focuses on explaining the preparation methods and processes to reduce repetition. For the specific structural description, please refer to the above-mentioned specific implementation methods, which will not be repeated here.

[0108] According to the embodiments of the present disclosure, Figure 4 As shown, a support electrode 200 is formed on the front surface of the substrate 110 based on the resonant structure, including:

[0109] S410: forming a sacrificial layer 140 on the front surface of the substrate 110;

[0110] According to an embodiment of the present disclosure, a resonant structure and a lower electrode layer 120 are formed on a substrate 110, wherein the resonant structure at least includes a piezoelectric layer 130 formed on the front surface of the substrate 110, so as to complete the preparation of the substrate 110. If necessary, a resonant cavity enclosed by the piezoelectric layer 130 needs to be prepared below the piezoelectric layer 130, such as the preparation of a bulk acoustic wave radio frequency filter (corresponding to a surface acoustic wave radio frequency filter having only the piezoelectric layer 130), such as Figure 5A shown.

[0111] According to the embodiment of the present disclosure, a protective sacrificial layer 140 is deposited on the front surface of the substrate 110 after the resonant structure and the lower electrode layer 120 are prepared, and the thickness is about The material of the sacrificial layer 140 can be silicon oxide. The sacrificial layer can protect the substrate 110 from being damaged in subsequent process steps. Then, based on the resonant structure on the front surface of the substrate 110 and the lower electrode layer 120 as a mask pattern, the sacrificial layer 140 is etched (for example, photolithography) or other processes are performed to form a support electrode opening 150 relative to the front surface of the substrate 110, such as Figure 5B shown.

[0112] According to an embodiment of the present disclosure, the sacrificial layer 140 needs to be removed in a subsequent process. If the RF filter is a bulk acoustic wave filter, the removal of the resonant cavity sacrificial layer needs to be performed after the support electrode 200 is prepared to avoid affecting the removal of the resonant cavity sacrificial layer.

[0113] S420: forming a seed layer on the sacrificial layer 140;

[0114] According to an embodiment of the present disclosure, a seed layer can be formed on the front surface of the substrate 110 by a physical vapor deposition method. The seed layer is a metal layer. The material of the seed layer can be titanium, tungsten, gold, copper, or a combination of the above metals, such as a titanium-tungsten-copper alloy material, or a titanium-tungsten-gold alloy material. The seed layer can help increase the adhesion between the metal layers between the lower surface of the support electrode 200 and the front surface of the substrate 110 to improve the diffusion capacity of metal atoms on the interface contact.

[0115] S430: forming a support electrode 200 on the seed layer based on the resonant structure,

[0116] According to the embodiment of the present disclosure, the support electrode 200 can be prepared by photolithography plus electroplating process; the material of the support electrode 200 can be copper, copper-like material, copper-like alloy material, etc. At this time, the seed layer formed in the above step S420 that is exposed on the front surface of the substrate 110 and outside the support electrode 200 area can be removed. At this time, only the seed layer between the support electrode 200 and the front surface of the substrate 110 is left, that is, the first seed layer and the second seed layer corresponding to the above support electrode 200, such as Figure 5C shown.

[0117] S440: forming a sealing structure on the end surface of the top end of the support electrode 200;

[0118] According to an embodiment of the present disclosure, a sealing structure can be formed on the end surface of the top end of the support electrode 200 by making a mask in photolithography and wet etching. The sealing structure can have a plurality of protrusions 230 or recesses 230. The protrusions 230 or recesses 230 appear as a sealing pattern in a top view of the end surface of the top end of the support electrode 200. The protrusion height of the protrusion 230 relative to the end surface is controlled to be greater than 1 μm, or the recess depth of the recess 230 relative to the end surface is controlled to be greater than 1 μm, such as Figure 5D shown.

[0119] It should be noted that if the seed layer formed in step S420 and exposed to the outside of the substrate 110 cannot be removed in step S430, it is necessary to remove it at this time. Specifically, the seed layer can be removed by a wet etching process. At this time, the first seed layer and the second seed layer located in the support electrode 200 can be formed accordingly.

[0120] Among them, refer to Figure 1A-Figure 2B The supporting electrode 200 includes: a first supporting electrode 210 and a plurality of second supporting electrodes 220, wherein the first supporting electrode 210 is protruded outwardly relative to the substrate 110 at the edge of the front surface of the substrate 110, and the first supporting electrode 210 forms a ring-shaped closed structure around the edge of the front surface of the substrate 110; each of the plurality of second supporting electrodes 220 is protruded outwardly relative to the substrate 110 at the middle of the front surface of the substrate 110 in a certain distribution, and the plurality of second supporting electrodes 220 are surrounded by the first supporting electrode 210 at the middle of the front surface of the substrate 110.

[0121] The sealing structure includes: a first sealing structure and a plurality of second sealing structures, wherein the first sealing structure is arranged on the end surface of the top end of the first supporting electrode 210; each of the plurality of second sealing structures corresponds to each of the plurality of second supporting electrodes 220 and is arranged on the end surface of the top end of each of the plurality of second supporting electrodes 220. The first sealing structure and each of the plurality of second sealing structures include a plurality of protrusions 230 or recesses 230 arranged accordingly.

[0122] According to the embodiments of the present disclosure, Figure 6 As shown, a thin film structure 300 is formed on the substrate 110 with the support electrode 200 as an interval, including:

[0123] S610: a film layer 310 is applied to the end surface of the substrate 110 having the support electrode 200 corresponding to the top of the support electrode 200.

[0124] According to the embodiment of the present disclosure, a protective sealing film, i.e., a film layer 310, can be attached to the entire surface of the substrate 110 having the support electrode 200 by a wafer-level film attaching process, and the support electrode 200 is used to support and form a protective cavity 420 of a resonant structure isolated from the outside. The film layer 310 can be a dry film. At this time, the sealing pattern on the sealing structure can play a role of fixing and adhering on the front surface of the film layer 310, so as to facilitate the later curing and sealing of the film layer 310, such as Fig. 7A , Figure 7B shown.

[0125] S620: Curing the film layer, the curing temperature is T, T≥250°C;

[0126] According to the embodiment of the present disclosure, the final protective sealing film layer 310 is formed by a high temperature curing process, and the curing temperature is controlled at above 250°C, so that the influence of high temperature on the film layer 310 in the subsequent processing steps can be tolerated. The thickness of the film layer 310 after curing can be 10μm to 60μm, such as Fig. 7A , Figure 7B shown.

[0127] S630: forming a plurality of through holes 410 and a plurality of anchor openings 440 on the solidified film layer 310;

[0128] According to an embodiment of the present disclosure, a plurality of through holes 410 for filling the lead electrode 320 and a plurality of anchor openings 440 for correspondingly forming a plurality of anchoring parts are formed above the support electrode 200 by a photolithography process. The plurality of through holes 410 can also be formed by other processes such as laser; the anchor openings 440 can also be prepared by mechanical cutting or laser processes, such as Fig. 7A , Figure 7B shown.

[0129] Among them, refer to Figure 1A-Figure 2B Each through hole 410 of the plurality of through holes 410 is arranged correspondingly to the middle position of the end surface of the top end of each second supporting electrode 220 of the plurality of second supporting electrodes 220 and penetrates the membrane layer 310; and a plurality of anchor openings 440 are arranged correspondingly above the first supporting electrode 210 along the edge of the membrane layer 310.

[0130] According to the embodiments of the present disclosure, Figure 8 As shown, a thin film structure 300 is formed on the substrate 110 with the support electrode 200 as an interval, and further includes:

[0131] S810: forming a plurality of lead electrodes 320 and a plurality of anchoring portions 350 on the back surface of the film layer 310 based on the plurality of through holes 410 and the plurality of anchoring openings 440 ;

[0132] According to an embodiment of the present disclosure, a seed layer can be formed on the back surface of the film layer 310 of the thin film structure having a plurality of through holes 410 and a plurality of anchor openings 440 by physical vapor deposition, and then the lead electrode 320 and the anchor portion 350 are prepared by photolithography and wiring (RDL) electroplating technology, and the thickness is controlled to be 5 μm to 40 μm, such as Fig.9A and Figure 2B As shown. Among them, the contact width k of the anchoring portion 350 and the first supporting electrode 210 is ≥10μm, and the length c is ≥40μm. The anchoring portion 350 can be a glue material or a metal material. In order to improve the sealing performance of the protective sealing film, the distribution of the anchoring portion 350 can be arranged around the device along the first supporting electrode 210, and is not limited to the anchoring of a local area of ​​the film layer 310. In addition, the lead electrode 320 not only plays the role of electrical interconnection between the device and the outside world (such as flip-chip interconnection or lead interconnection, etc.), but also can strengthen the strength of the film layer 310. Its coverage area should be expanded as much as possible to achieve better heat dissipation effect.

[0133] S820: forming a plurality of passivation layers 330 correspondingly on the plurality of lead electrodes 320;

[0134] According to an embodiment of the present disclosure, a passivation layer 330 may be prepared on the back surface of the lead electrode 320 by coating or chemical vapor deposition, which may be used to protect the lead electrode 320, for example, to prevent subsequent processing steps from causing damage to the lead electrode 320. Fig. 9B shown.

[0135] S830: forming a plurality of passivation holes 430 correspondingly based on the plurality of passivation layers 330;

[0136] According to an embodiment of the present disclosure, the passivation layer 330 formed on the outer surface of the lead electrode 320 can be etched by etching processes such as photolithography at the outer surface position of the lead electrode 320 on the back surface of the film layer 310 corresponding to the upper end surface of the first support electrode 210, so as to form a passivation hole 430 penetrating the passivation layer 330 on the passivation layer 330, so as to make the back electrode 340 formed in the subsequent step contact with the lead electrode 320, that is, to achieve electrical connection between the two, such as Fig. 9B shown.

[0137] S840: forming a plurality of back electrodes 340 corresponding to the plurality of passivation holes 430;

[0138] According to an embodiment of the present disclosure, a flip-chip electrode in contact with the outer surface of the lead electrode 320, i.e., a back electrode 340, can be formed at the position of the above-mentioned passivation hole 430 by electroplating, and its height is controlled to be 30 μm to 150 μm. Specifically, a metal seed layer can be formed on the back surface of the thin film structure with the passivation hole 430 by physical vapor deposition, and the back electrode 340 can be formed on the passivation hole 430 by photolithography and electroplating. Fig. 9C shown.

[0139] Among them, refer to Figure 1A-Figure 2B Each of the plurality of lead electrodes 320 is filled and arranged correspondingly with each of the plurality of through holes 410, the lower end of each of the plurality of lead electrodes 320 is in contact with the end surface of the top end of each of the plurality of second supporting electrodes 220, the upper end of each of the plurality of lead electrodes 320 is laid on the back surface of the film layer 310, and the inner surface of the upper end of each of the plurality of lead electrodes 320 is in contact with the back surface of the film layer 310; each of the plurality of anchoring portions 350 is correspondingly arranged in each of the plurality of anchoring openings 440. Each of the plurality of passivation layers 330 corresponds to each of the plurality of lead electrodes 320 and is covered on the outer surface of the upper end of each of the plurality of lead electrodes 320; each of the plurality of passivation holes 430 corresponds to each of the plurality of back electrodes 340 and is opened on each of the plurality of passivation layers 330; each of the plurality of back electrodes 340 is arranged on the outer surface of the upper end of each of the plurality of lead electrodes 320 corresponding to each of the plurality of lead electrodes 320, and is correspondingly arranged directly above the first support electrode 210.

[0140] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A radio frequency filter, characterized in that: include: Matrix, A supporting electrode is convexly disposed on the front surface of the substrate; A thin film structure is formed on the substrate and spaced apart from the supporting electrodes. The end surface of the top end of the supporting electrode is in sealing contact with the front surface of the thin film structure, and the supporting electrode comprises: A first supporting electrode, the first supporting electrode is protruding outwardly from the substrate at the edge of the front surface of the substrate, and the first supporting electrode forms an annular closed structure around the edge of the front surface of the substrate; A plurality of second supporting electrodes, each of the plurality of second supporting electrodes is protruded outwardly relative to the substrate in a certain distribution at the middle of the front surface of the substrate, and the plurality of second supporting electrodes are surrounded by the first supporting electrode at the middle of the front surface of the substrate; The film structure comprises: A membrane layer, wherein the membrane layer is arranged on the substrate with the support electrode spaced therebetween, and the end surface of the top end of the support electrode is in sealing contact with the front surface of the membrane layer, wherein the thickness of the membrane layer is m, 10 μm≤m≤60 μm; A plurality of through holes, each of the plurality of through holes is arranged corresponding to a middle position of an end surface of a top end of each of the plurality of second supporting electrodes and is penetrated through the film layer; A plurality of lead electrodes, each of the plurality of lead electrodes is filled and arranged corresponding to each of the plurality of through holes, a lower end of each of the plurality of lead electrodes is in contact with an end surface of a top end of each of the plurality of second supporting electrodes, an upper end of each of the plurality of lead electrodes is laid on the back surface of the film layer, an inner surface of an upper end of each of the plurality of lead electrodes is in contact with the back surface of the film layer, wherein a thickness of each of the plurality of lead electrodes at an upper end located on the back surface of the film layer is y, 5μm≤m≤40μm; and A plurality of back electrodes, each of the plurality of back electrodes is arranged on the outer surface of the upper end of each of the plurality of lead electrodes corresponding to each of the plurality of lead electrodes, and is correspondingly arranged directly above the first supporting electrode, wherein the height of the back electrode is b, 30 μm≤b≤150 μm; The area of ​​the back surface of the film layer is s1, the distribution area of ​​the upper end of each of the multiple lead electrodes on the back surface of the film layer is s2, the number of the multiple lead electrodes is n, ∆s=(n×s2) / s1, ∆s≥0.

2.

2. The radio frequency filter according to claim 1, characterized in that: The supporting electrode further comprises: a first seed layer, wherein the first seed layer is disposed between the first supporting electrode and the substrate; a plurality of second seed layers, each of the plurality of second seed layers being relatively arranged between each of the plurality of second supporting electrodes and the substrate; The material of the first seed layer and each of the plurality of second seed layers is titanium, tungsten, gold, copper or a combination of the above metals.

3. The radio frequency filter according to claim 1, characterized in that: The radio frequency filter also includes: A protection cavity, which is a cavity space between the first supporting electrode, the plurality of second supporting electrodes and the front surface of the substrate; Among them, the distance between the front surface of the substrate and the end surface of the top of the first supporting electrode is j1, the distance between the front surface of the substrate and the end surface of the top of each second supporting electrode in the plurality of second supporting electrodes is j2, 10μm≤j1≤40μm, 10μm≤j2≤40μm; ∆j=|j1-j2|, ∆j≤10μm.

4. The radio frequency filter according to claim 3, characterized in that: The substrate comprises: A resonant structure, wherein the resonant structure is arranged on the front surface of the substrate corresponding to the protective cavity, A plurality of lower electrode layers, each of the plurality of lower electrode layers corresponds to the lower surface of each of the plurality of second supporting electrodes and is concave inwardly on the front surface of the substrate, and the material of the lower electrode layer is copper, gold, molybdenum, aluminum or a combination of the above metals; Wherein, the resonant structure at least comprises: A piezoelectric layer is disposed on the front surface of the substrate corresponding to the protection cavity.

5. The radio frequency filter according to claim 4, characterized in that: The substrate also includes: a plurality of spacer layers, each of the plurality of spacer layers corresponds to the lower surface of each of the plurality of lower electrode layers, and is disposed between each of the plurality of lower electrode layers and the substrate, Wherein, the material of the spacer layer is titanium, tungsten, nickel, chromium or a combination of the above metals.

6. The radio frequency filter according to claim 5, characterized in that: The membrane structure also includes: A plurality of passivation layers, each of the plurality of passivation layers corresponds to each of the plurality of lead electrodes and is covered on an outer surface of an upper end of each of the plurality of lead electrodes; A plurality of passivation holes, each of the plurality of passivation holes corresponds to each of the plurality of back electrodes and is opened on each of the plurality of passivation layers.

7. The radio frequency filter according to claim 5, characterized in that: The membrane structure also includes: A plurality of anchor openings, wherein the plurality of anchor openings are arranged above the first supporting electrode along the edge of the film layer, and the projection size of the anchor openings on the back surface of the film layer is length c and width k, where c≥40 μm and k≥10 μm; A plurality of anchoring portions, each of the plurality of anchoring portions is correspondingly disposed in each of the plurality of anchoring openings, and a thickness of the anchoring portion is d, 5 μm≤d≤40 μm.

8. The radio frequency filter according to claim 7, characterized in that: Each of the plurality of anchoring portions comprises: An anchor end, the anchor end is correspondingly arranged in the anchor opening; A fixed end, the fixed end being correspondingly arranged on the back surface of the film layer; The anchor end and the top end are connected to each other and are designed as an integral unit.

9. The radio frequency filter according to claim 1, characterized in that: The supporting electrode further comprises: A first sealing structure, wherein the first sealing structure is disposed on an end surface of a top end of the first supporting electrode; A plurality of second sealing structures, each of the plurality of second sealing structures corresponds to each of the plurality of second supporting electrodes and is disposed on an end surface of a top end of each of the plurality of second supporting electrodes; The first sealing structure and each of the plurality of second sealing structures include a plurality of correspondingly arranged protruding portions or recessed portions, the height of the protruding portion is t, the depth of the recessed portion is a, t≥1 μm, a≥1 μm.

Images