WO2021146848A1 - 射频滤波器的制备方法 - Google Patents

射频滤波器的制备方法 Download PDF

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Publication number
WO2021146848A1
WO2021146848A1 PCT/CN2020/073258 CN2020073258W WO2021146848A1 WO 2021146848 A1 WO2021146848 A1 WO 2021146848A1 CN 2020073258 W CN2020073258 W CN 2020073258W WO 2021146848 A1 WO2021146848 A1 WO 2021146848A1
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Prior art keywords
electrode
supporting
electrodes
supporting electrode
layer
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PCT/CN2020/073258
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English (en)
French (fr)
Inventor
蒋将
李平
王伟
祝明国
胡念楚
贾斌
Original Assignee
开元通信技术（厦门）有限公司
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Priority to US17/793,811 priority Critical patent/US20230126725A1/en
Priority to PCT/CN2020/073258 priority patent/WO2021146848A1/zh
Publication of WO2021146848A1 publication Critical patent/WO2021146848A1/zh

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/64—Filters using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/08—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of resonators or networks using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/05—Holders; Supports
    • H03H9/0504—Holders; Supports for bulk acoustic wave devices
    • H03H9/0514—Holders; Supports for bulk acoustic wave devices consisting of mounting pads or bumps
    • H03H9/0523—Holders; Supports for bulk acoustic wave devices consisting of mounting pads or bumps for flip-chip mounting
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/05—Holders; Supports
    • H03H9/058—Holders; Supports for surface acoustic wave devices
    • H03H9/059—Holders; Supports for surface acoustic wave devices consisting of mounting pads or bumps
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/25—Constructional features of resonators using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/46—Filters
    • H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
    • H03H9/58—Multiple crystal filters

Definitions

  • the present disclosure relates to the technical field of filters, and in particular to a method for preparing radio frequency filters.
  • radio frequency filters are usually divided into: bulk acoustic wave filters and surface acoustic wave filters.
  • surface acoustic wave filters generally work at frequencies below 2.5G
  • bulk acoustic wave filters work at frequencies from 1.5G to 10G.
  • a relatively closed cavity ie, protective cavity
  • a relatively closed cavity ie, protective cavity
  • the conventional method 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 go through a series of complex processes
  • a protective substrate which is usually silicon, glass, ceramic, metal shell, etc.
  • the following materials, processes and equipment can be used: 1) Double-polished high-resistance silicon wafers as the protective substrate 2) Through silicon via (TSV) and deep hole electrode filling technology are used for through-hole electrode processing; 3) The material gold is used as the wafer bonding and electrode material; 4) The expensive wafer bonding and lateral deposition are required Capable of physical vapor deposition equipment.
  • the entire preparation process of the radio frequency filter is longer and the process is more difficult to achieve.
  • the application of the above materials, processes and equipment causes the cost of the single preparation of the BAW device to be expensive, which directly affects the large-scale application of the product and the market competition. force.
  • the present disclosure proposes a method for preparing a radio frequency filter, including:
  • a thin film structure separated by the supporting electrode is formed on the substrate.
  • the forming a support electrode on the front surface of the substrate based on the resonance structure includes:
  • a sacrificial layer is formed on the front surface of the substrate
  • 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 includes:
  • a plurality of second supporting electrodes each of the plurality of second supporting electrodes is arranged outwardly with respect to the base in a certain distribution protruding in the middle of the front surface of the base, and at the same time, the plurality of second supporting electrodes The two supporting electrodes are surrounded by the first supporting electrode in the middle of the front surface of the base body.
  • the method further includes:
  • the first seed layer is disposed between the first supporting electrode and the substrate;
  • Each second seed layer of the plurality of second seed layers is disposed oppositely between each second support electrode of the plurality of second support electrodes and the substrate;
  • each second seed layer of the first seed layer and the plurality of second seed layers is titanium, tungsten, gold, copper, or a combination of the foregoing metals.
  • the method further includes:
  • the sealing structure includes:
  • a first sealing structure the first sealing structure being disposed on the end surface of the top end of the first supporting electrode
  • each of the plurality of second sealing structures corresponds to each of the plurality of second supporting electrodes, and is disposed on the plurality of second supporting electrodes The end surface of the top end of each second supporting electrode in the supporting electrodes;
  • each second sealing structure of the first sealing structure and the plurality of second sealing structures includes a plurality of protruding portions or recesses provided correspondingly.
  • the forming a thin film structure spaced from the supporting electrode on the substrate includes:
  • a film layer is pasted on the substrate with the supporting electrode and the end surface corresponding to the top end of the supporting electrode,
  • Curing the film layer, the curing temperature is T, T ⁇ 250°C;
  • the membrane layer is arranged on the substrate with the supporting electrode interposed, and the end surface of the top end of the supporting electrode is in sealed contact with the front surface of the membrane layer, wherein the thickness of the membrane layer after being cured is m, 10 ⁇ m ⁇ m ⁇ 60 ⁇ m.
  • the method includes:
  • each through hole of the plurality of through holes is arranged corresponding to the middle position of the end surface of the top end of each second supporting electrode of the plurality of second supporting electrodes, and penetrates the film layer;
  • the plurality of anchoring openings are correspondingly arranged above the first supporting electrode along the edge of the film layer;
  • the plurality of anchoring openings are correspondingly arranged above the first supporting electrode along the edge of the film layer, and the projected dimensions of the anchoring openings on the back surface of the film layer are length c, width k, c ⁇ 40 ⁇ m, k ⁇ 10 ⁇ m.
  • the forming a thin film structure spaced from the supporting electrode on the substrate further includes:
  • each lead electrode of the plurality of lead electrodes is filled and arranged corresponding to each through hole of the plurality of lead electrodes, and the lower end of each lead electrode of the plurality of lead electrodes is connected to the plurality of lead electrodes.
  • the end surface of the top end of each second support electrode in the second support electrodes is in contact with each other, the upper end of each lead electrode in the plurality of lead electrodes is laid on the back surface of the film layer, and the upper end of each lead electrode of the plurality of lead electrodes is laid on the back surface of the film layer.
  • the inner surface of the upper end of each lead electrode is in contact with the back surface of the film layer;
  • Each of the plurality of anchoring portions is correspondingly disposed in each of the plurality of anchoring openings, and the thickness of the anchoring portion is d, and 5 ⁇ m ⁇ d ⁇ 40 ⁇ m.
  • the forming a thin film structure spaced from the supporting electrode on the substrate further includes:
  • each passivation layer of the plurality of passivation layers corresponds to each of the plurality of lead electrodes, and is arranged on the outer surface of the upper end of each of the plurality of lead electrodes superior;
  • Each passivation hole of the plurality of passivation holes corresponds to each of the plurality of back electrodes and is opened on each passivation layer of the plurality of passivation layers.
  • the forming a thin film structure spaced from the supporting electrode on the substrate further includes:
  • 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 corresponds to It is arranged directly above the first supporting electrode.
  • the supporting electrode is formed on the front surface of the substrate based on the resonance structure, and the radio frequency filter includes:
  • a protection cavity the protection cavity being a cavity space between the first supporting electrode, the plurality of second supporting electrodes and the front surface of the substrate;
  • the distance between the front surface of the base body and the end surface of the top end of the first supporting electrode is j1
  • the distance between the front surface of the base body and the end surface of the top end of each second supporting electrode of the plurality of second supporting electrodes is j1.
  • FIG. 1A is an internal three-dimensional schematic diagram of a radio frequency filter without a film structure according to an embodiment of the present disclosure
  • FIG. 1B is a three-dimensional schematic diagram of the appearance of the radio frequency filter covered with the film layer in FIG. 1A according to an embodiment of the present disclosure
  • FIG. 1C is a three-dimensional schematic diagram of the appearance of the radio frequency filter equipped with an anchor portion and a lead electrode in FIG. 1B according to an embodiment of the present disclosure
  • FIG. 2A is a schematic structural cross-sectional view of a radio frequency filter with a back electrode corresponding to the B-B' tangent line in FIG. 1C according to an embodiment of the present disclosure
  • FIG. 2B is a schematic cross-sectional view of the structure of the radio frequency filter corresponding to the A-A' tangent line in FIG. 1C according to an embodiment of the present disclosure
  • FIG. 3 is a schematic diagram of the preparation process of the radio frequency filter corresponding to FIG. 2A and FIG. 2B in an embodiment according to the present disclosure
  • FIG. 4 is a schematic diagram of a preparation process of a radio frequency filter according to an embodiment of the present disclosure
  • 5A is a schematic structural diagram of a stage of a preparation process of a radio frequency filter according to an embodiment of the present disclosure
  • FIG. 5B is another schematic structural diagram of a stage of the preparation process of the radio frequency filter in an embodiment of the present disclosure
  • FIG. 5C is another schematic structural diagram of a stage of the preparation process of the radio frequency filter according to an embodiment of the present disclosure.
  • FIG. 5D is still another schematic structural diagram of a stage of the preparation process of the radio frequency filter according to an embodiment of the present disclosure.
  • FIG. 6 is a schematic diagram of another preparation process of a radio frequency filter according to an embodiment of the present disclosure.
  • FIG. 7A is a schematic structural diagram of another stage of the preparation process of the radio frequency filter in an embodiment of the present disclosure.
  • Fig. 7B is another structural schematic diagram corresponding to the A-A' tangent line in Fig. 1B in another stage of the preparation process of the radio frequency filter in an embodiment of the present disclosure
  • FIG. 8 is a schematic diagram of another preparation process of a radio frequency filter according to an embodiment of the present disclosure.
  • FIG. 9A is a schematic structural diagram of another stage of the preparation process of the radio frequency filter according to an embodiment of the present disclosure.
  • FIG. 9B is another schematic structural diagram of another stage of the preparation process of the radio frequency filter according to an embodiment of the present disclosure.
  • FIG. 9C is another schematic structural diagram of another stage of the preparation process of the radio frequency filter according to an embodiment of the present disclosure.
  • a radio frequency filter as shown in FIGS. 1A-1C and FIGS. 2A-2B, including: a substrate 110, a supporting electrode 200, and a thin film structure 300,
  • the supporting electrode 200 is outwardly protruding from the front surface of the base 110 relative to the base 110;
  • the thin film structure 300 is formed on the substrate 110 with the supporting electrode 200 spaced apart, and the end surface of the top end of the supporting electrode 200 is in sealed contact with the front surface of the thin film structure 300.
  • the base 110 may be all or part of the wafer base. Specifically, for example, when the base 110 is the whole of the wafer base, the radio frequency filter of the present disclosure It may be a single RF filter structure.
  • the RF filter of the present disclosure may be a single device structure in the array structure of the RF filter formed by the wafer substrate.
  • the wafer substrate can be a wafer-level substrate with an area size of 4 inches, 6 inches, and 8 inches
  • the wafer-level substrate material can be silicon, glass, and three-five group semiconductor materials, which are used as the material of the present disclosure.
  • the base 110 can also be used to provide a substrate for supporting electrodes, and at the same time form a protective space for the resonance structure of the corresponding radio frequency filter.
  • the present disclosure provides a supporting electrode 200 formed on the front surface of the base 110, and the supporting electrode 200 protrudes outwardly from the base 110.
  • the front surface of the base 110 may be integrally formed with the base 110.
  • the “front surface” and the subsequent “back surface” are only defined relative to the location of the resonant structure, that is, the surface on which the resonant structure is located or the surface facing the resonant structure, which is referred to in the present disclosure as "Front surface", on the contrary, is called "back surface”.
  • the supporting electrode 200 can be made of copper, or a copper-like material, a copper-like alloy material, etc., which greatly reduces the cost.
  • 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 with respect to the gold material, the electrode material contact of the present disclosure achieves better bonding strength than the gold material contact, as well as better resonance effect and sealing strength.
  • Copper-like material or copper-like alloy material means that the characteristics of the material are similar to copper itself, for example, the resistivity is close.
  • the thin film structure 300 has at least one film layer, which is directly attached to the substrate 110 with the supporting electrode 200 through a film coating process.
  • the supporting electrode is used to support the thin film structure 300 to form a protective space or a resonance space of the resonant structure between the thin film structure 300 and the base 110.
  • the present disclosure may provide a sealing structure on the end surface of the top end of the supporting electrode for contact sealing with the front surface of the film layer of the thin film structure 300.
  • the present disclosure structurally overcomes the technical prejudice of "using the thin film structure 300 to replace the traditional protective wafer substrate” in the art, and replaces the traditional protective wafer substrate with a film layer, so that the packaging of the radio frequency filter can be simply covered.
  • the film (corresponding to the film layer of the present disclosure) can effectively encapsulate the sealed cavity of the device, 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, and the cost of the device is greatly reduced ,
  • the processing cycle of packaged products has been shortened by more than half, which can be said to be a milestone in the history of RF filter device research and development.
  • the supporting electrode 200 includes: a first supporting electrode 210, a first seed layer, a plurality of second supporting electrodes 220, and a plurality of second seed layers,
  • the first supporting electrode 210 protrudes outward from the edge of the front surface of the base 110 relative to the base 110, and at the same time, the first supporting electrode forms an annular closed structure around the edge of the front surface of the base 110; the first supporting electrode 210 is used to contrast the film structure 300 provides edge support for the device structure.
  • the first support electrode 210 can be formed of copper, or a copper-like material, a copper-like alloy material, etc., to reduce material costs.
  • the first seed layer is disposed between the first support electrode 210 and the base 110; the first seed layer is used to connect the first support electrode 210 and the base 110.
  • a transition layer is provided between the 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 metal atom diffusion ability on the interface contact.
  • each of the plurality of second supporting electrodes 220 is protruded on the front side of the base 110 in a certain distribution relative to the base 110.
  • the plurality of second supporting electrodes 220 are surrounded by the first supporting electrodes 210 in the middle of the front surface of the base 110.
  • the certain distribution may be a uniform distribution on the front surface of the substrate 110 in the space surrounded by the first support electrode 210 to effectively support the film layer 310 and improve the structural strength of the device.
  • the second supporting electrode 220 is used to provide the middle supporting function of the device structure to the thin film structure 300.
  • the second supporting electrode 220 may be formed of copper, or a copper-like material, a copper-like alloy material, etc., to reduce material cost.
  • a plurality of second seed layers are disposed oppositely between each of the plurality of second support electrodes 220 and the base 110;
  • the second seed layer is used to provide a transition layer between the second support electrode 220 and the base 110 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 base 110, In order to improve the diffusion ability of metal atoms on the interface contact.
  • the material of each second seed layer of the first seed layer and the plurality of second seed layers is titanium, tungsten, gold, copper, or a combination of the foregoing metals, such as titanium tungsten plus copper alloy Or titanium-tungsten plus gold alloy and so on.
  • the radio frequency filter further includes: a protective cavity 420, the protective cavity 130 is the above-mentioned protective space, and is used to provide a resonant structure on the base 110 To protect the space, it can also be used to provide resonance space for the resonant structure.
  • the protection cavity 420 is the cavity space between the first supporting electrode 210, the plurality of second supporting electrodes 220, and the front surface of the base 110;
  • the shape of the cavity 420 can be set 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.
  • the main space of the protective 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.
  • the distance between the front surface of the base 110 and the end surface of the top end of the first support electrode 210 is j1, and the front surface of the base 110 and the plurality of second support electrodes
  • the distance j1 can be understood as the height of the first supporting electrode 210
  • the distance j2 can be understood as the height of the second supporting electrode 220, which together determine the depth of the protection cavity 420 relative to the device structure.
  • the difference in the preparation process (for example, electroplating process) and formation position (middle or edge) of the electrode 220 causes the larger the overall height of the supporting electrode 200, the larger the ⁇ j.
  • the design of ⁇ j ⁇ 10 ⁇ m is beneficial to the support electrode 200 after the film layer 310 of the film structure 300 is pasted, which can better support the film layer 310, prevent the structure of the film layer 310 from being deformed, and make the structure more flat.
  • the base 110 includes: a resonant structure and a plurality of lower electrode layers 120.
  • the resonant structure is provided on the front surface of the base 110 corresponding to the protection cavity 420, and is used to generate a device Resonance effect.
  • each of the plurality of lower electrode layers 120 corresponds to the thickness of each of the plurality of second support electrodes 220.
  • the lower surface is recessed on the front surface of the base 110.
  • the material of the lower electrode layer 120 is copper, gold, molybdenum, aluminum or a combination of the above metals; the lower electrode layer 120 can connect the resonant structure on the base 110 with the second support
  • the electrode 220 is electrically connected, and the second supporting electrode 220 can also function as an electrical connection with the lower electrode layer 120.
  • the resonant structure at least includes a piezoelectric layer 130.
  • the piezoelectric layer 130 is provided on the front surface of the base 110 corresponding to the protective cavity 420, and is used to achieve a certain The resonance function of, to help the realization of the resonance effect.
  • the resonant structure may also include a resonant cavity, which may be a concave space located below the piezoelectric layer and recessed on the front surface of the base 110.
  • the piezoelectric layer may also be used to seal the resonance at this time. Cavity.
  • the base 110 further includes: a plurality of spacer layers, each of the plurality of spacer layers corresponds to each of the plurality of lower electrode layers 120
  • the lower surface of the layer 120 is disposed between each of the plurality of lower electrode layers 120 and the base 110.
  • the spacer layer is used to provide a transition layer between the lower electrode layer 120 and the base 110 to help The adhesion between the metal layers is increased between the outer surface of the lower electrode layer 120 and the base 110 to improve the metal atom diffusion ability on the interface contact.
  • the material of the spacer layer is titanium, tungsten, nickel, chromium, or a combination of the foregoing metals.
  • 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
  • the spaced support electrode 200 is disposed on the base 110, and the end surface of the top end of the support electrode 200 is in sealed contact with the front surface of the film layer 310.
  • the thickness of the film layer is m, 10 ⁇ m ⁇ m ⁇ 60 ⁇ m.
  • the film layer 310 is the main structure of the film structure 300, and may 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 may be 20%-50% of the thickness m'before curing. In addition, the film layer 310 may be all or part of a wafer-level film-coated structure.
  • the film layer 310 creatively replaces the traditional wafer substrate as the protective layer, and at the same time, the device packaging process between the film layer 310 and the substrate 110 is realized, the cost is lower, and the device is easier to process.
  • the film layer 310 overcomes the technical prejudice of the “thin film layer as a protective layer” in the field, and replaces the traditional protective wafer substrate 110 with the thin film structure 300, so that the packaging of the radio frequency filter can be achieved through simple film coating.
  • the effective packaging of the sealed cavity of the device, 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 cost of the device is greatly reduced, and the competitiveness of the device is improved; more importantly, it has achieved expectations Less technical effect: the processing cycle of packaged products is shortened by more than half, and processes and corresponding equipment such as deep silicon etching, deep hole sputtering, high temperature and high pressure bonding are no longer needed, which greatly improves the preparation efficiency and saves preparation time and The cost of preparation and the cost of packaging and commissioning have dropped significantly, which can be said to be a milestone in the history of RF filter device research and development.
  • each through hole 410 of the plurality of through holes 410 is connected to the top end of each second supporting electrode 220 of the plurality of second supporting electrodes 220.
  • the middle position of the end surface is set correspondingly and penetrates 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 beneficial to the distribution of the lead electrode 320 on the back surface of the film layer 310 to be more regular. control.
  • each of the plurality of lead electrodes 320 is filled and arranged corresponding to each of the plurality of through holes 410.
  • the lower end of each lead electrode 320 in the lead electrodes 320 is in contact with the end surface of the top end of each second support electrode 220 in the plurality of second support electrodes 220, and the upper end of each lead electrode 320 in the plurality of lead electrodes 320 Laying on the back surface of the film layer 310, the inner surface of the upper end of each lead electrode 320 of the plurality of lead electrodes 320 is in contact with the back surface of the film layer 310, wherein each lead electrode 320 of the plurality of lead electrodes 320 is located
  • the thickness of the upper end of the back surface of the film layer 310 is y, 5 ⁇ m ⁇ m ⁇ 40 ⁇ m.
  • the lower end portion of the lead electrode 320 is filled in the through hole 410.
  • the lower surface of the lower end portion of the lead electrode 320 is in sealed contact with the top end surface of the second support electrode 220.
  • the lower surface of the second support electrode 220 is in contact with the lower electrode layer 120 on the base 110.
  • the lead electrode 320 is used to connect the lower electrode layer of the device to the outside.
  • 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 second support electrode 220 and the first support Corresponding between the electrodes 210 on the back surface area of the film layer 310.
  • 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 lead electrode 320 can also be used to increase the structural strength of the film layer 310 and increase the overall device Heat dissipation efficiency.
  • the material of the lead electrode 320 may be a metal such as copper.
  • each back electrode 340 of the plurality of back electrodes 340 and each of the plurality of lead electrodes 320 are arranged in a plurality of Each of the lead electrodes 320 is located on the outer surface of the upper end of each lead electrode 320 and is correspondingly disposed directly above the first support electrode 210.
  • the first support electrode 210 can be used to simultaneously realize the alignment of the film layer 310 and the back surface thereof.
  • the supporting function of the back electrode 340 is not limited to realize the alignment of the film layer 310 and the back surface thereof.
  • the height of the back electrode 340 is b, 30 ⁇ m ⁇ b ⁇ 150 ⁇ m, 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 electrical connection between the device structure and the outside.
  • the thin film structure 300 further includes: a plurality of passivation layers 330 and a plurality of passivation holes 430, each passivation layer 330 of the plurality of passivation layers 330 and a plurality of Each of the lead electrodes 320 corresponds to and covers the outer surface of the upper end of each of the multiple lead electrodes 320.
  • the passivation layer 330 can protect the lead electrode 320 (for example, damage in subsequent processes) to increase device reliability.
  • 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 type. Material or colloidal material.
  • each passivation hole 430 of the plurality of passivation holes 430 corresponds to each back electrode 340 of the plurality of back electrodes and is opened in the plurality of passivation layers 330 330 on each passivation layer.
  • the passivation hole 430 is used to open the passivation layer 330 and at the same time provide a space for the back electrode 340 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.
  • the membrane structure 300 further includes: a plurality of anchoring openings 440 and a plurality of anchoring portions 350, and the plurality of anchoring
  • the opening 440 is correspondingly arranged above the first support electrode 210 along the edge of the film layer 310, and the projected size of the anchor opening 440 on the back surface of the film layer 310 is length c, width k, c ⁇ 40 ⁇ m, k ⁇ 10 ⁇ m, specifically as follows As shown in Figure 1B; the larger the values of c and k, the larger the anchoring opening 440 will determine the contact area between the anchoring portion 350 and the membrane layer 310, so that the anchoring opening 440 is used to provide an anchoring position for the anchoring portion 350 to It is beneficial to seal the film layer 310 on the substrate 110 better.
  • the bottom surface of the anchor opening 440 is the upper surface of the first support electrode 210, that is, the thickness of the film layer 310 is the height of the anchor opening 440.
  • the values of c and k can be set according to the size of the first supporting electrode 210.
  • each of the plurality of anchor portions 350 is correspondingly disposed in the plurality of anchor openings 440
  • the thickness of the anchor portion 350 is d, and 5 ⁇ m ⁇ d ⁇ 40 ⁇ m.
  • the material of the anchoring portion 350 may be metal to increase the strength of the film layer 310 and at the same time to enhance the sealing performance between the film layer 310 and the first support electrode 210.
  • the film layer can be A certain strength and corrosion resistance are achieved by 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 prolong the life of the device.
  • each anchoring portion 350 of the plurality of anchoring portions 350 may be an L-shaped design, including: anchoring The L-shaped design of the anchor end at the upper end of the anchor portion 350 and the fixed end at the lower end of the anchor portion 350 is more conducive to the anchoring portion 350 to achieve the sealing effect and strength enhancement benefits brought by the anchoring.
  • the anchor end is correspondingly disposed in the anchor opening 440; its thickness d may be the thickness of the anchor end of the anchor portion 350 anchored to the edge of the back surface of the membrane layer 310, and the anchor end is used to realize the alignment to the membrane layer 310.
  • the back surface provides a top-down anchoring force to help the anchoring effect.
  • the fixed end is correspondingly disposed on the back surface of the film layer, and its thickness d may be such that the anchor portion 350 is anchored in the side surface of the film layer 310 and the anchor opening on the upper surface of the first support electrode 210
  • the width of the fixed end is equivalent to the above-mentioned k value.
  • the top end is used to provide bottom-up and outside-in anchoring force between the side surface of the membrane layer 310 and the first supporting electrode layer 210 to help achieve the anchoring effect.
  • the supporting electrode 200 further includes a sealing structure.
  • the sealing structure is used when the film layer 310 is pasted and before the curing process (at this time, the front surface of the film layer 310 has a certain Adhesion to facilitate sealing in the mating sealing structure), a sealing contact with the sealing structure is formed on the front surface of the film layer 310. After the curing process, the front surface of the film layer 310 will complete the device through the sealing structure. Structural sealing.
  • the sealing structure includes: a first sealing structure and a plurality of second sealing structures.
  • the first sealing structure is disposed on the end surface of the top end of the first supporting electrode 210;
  • the sealing between the supporting electrode 210 and the front surface of the film layer 310 is used to realize the peripheral packaging of the device.
  • Each second sealing structure of the plurality of second sealing structures corresponds to each of the plurality of second supporting electrodes, and is disposed on the top end of each of the plurality of second supporting electrodes. End surface; used for the sealing between the multiple second supporting electrodes 220 and the front surface of the film layer 310 to achieve the internal packaging of the device.
  • each second sealing structure of the first sealing structure and the plurality of second sealing structures includes a plurality of correspondingly arranged protrusions or recesses, and the height of the protrusions is Is t, the depth of the recess is a, t ⁇ 1 ⁇ m, and a ⁇ 1 ⁇ m.
  • the design of the protruding part or the recessed part will be more conducive to the fixation between the first sealing structure and the second sealing structure and the front surface of the film layer 310 (for example, preventing slippage) during the coating-curing process of the film layer 310. , Misalignment, etc.), connection and sealing.
  • Another aspect of the present disclosure provides a preparation method, as shown in FIG. 3, for preparing the above-mentioned radio frequency filter, including:
  • S310 forming a resonant structure on the front surface of the base 110; specifically, the piezoelectric layer 130, the lower electrode layer 120, etc. of the resonant structure may be formed on the front surface of the base 110 to form the basic structure of the resonance effect of the radio frequency filter .
  • S320 Form the support electrode 200 on the front surface of the base 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 base 110.
  • the preparation of the support electrode 200 can be achieved by electroplating on the front surface of the base 110 according to a mask pattern to strengthen the contact strength between the support electrode 200 and the front surface of the base 110.
  • S330 forming a thin film structure 300 spaced from the supporting electrode 200 on the base 110, and the end surface of the top end of the supporting electrode 200 is in sealed contact with the front surface of the thin film structure 300.
  • the film layer 310 of the thin film structure 300 may be fixed and sealed on the end surface of the top end of the supporting electrode 200 through a process of attaching and curing, so as to realize the packaging of the device.
  • forming the supporting electrode 200 on the front surface of the base 110 based on the resonance structure includes:
  • a resonant structure and a lower electrode layer 120 are formed on the base 110, wherein the resonant structure at least includes a piezoelectric layer 130 formed on the front surface of the base 110 to complete the preparation of the base 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 radio frequency filter with only the piezoelectric layer 130), As shown in Figure 5A.
  • a process protective sacrificial layer 140 is deposited on the front surface of the substrate 110 where the resonance structure and the lower electrode layer 120 are prepared, with a thickness of about Between -1 ⁇ m, the material of the sacrificial layer 140 may be silicon oxide.
  • the sacrificial layer can protect the substrate 110 during subsequent processing steps.
  • the sacrificial layer 140 is etched (for example, photolithography) or other processes to realize the formation of the support electrode 200 on the front surface of the substrate 110. Opening 150, as shown in Figure 5B.
  • the sacrificial layer 140 needs to be removed in the subsequent process. If the radio frequency filter is a bulk acoustic wave filter, the sacrificial layer of the resonant cavity needs to be removed after the support electrode 200 is prepared to avoid affecting the resonant cavity. Removal of the sacrificial layer.
  • 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, and the material of the seed layer can be titanium, tungsten, gold, copper, or a combination of the foregoing metals. Combinations, such as titanium tungsten plus copper alloy material, or titanium tungsten plus 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, so as to improve the metal atom diffusion ability on the interface contact.
  • the supporting electrode 200 may be prepared by a photolithography and electroplating process; the material of the supporting electrode 200 may be copper, or a copper-like material, a copper-like alloy material, or the like.
  • the seed layer exposed on the front surface of the substrate 110 and outside the area of the support electrode 200 formed in the above step S420 can be selectively removed.
  • only the seed layer between the support electrode 200 and the front surface of the substrate 110 is left. That is, corresponding to the first seed layer and the second seed layer of the above-mentioned supporting electrode 200, as shown in FIG. 5C.
  • a sealing structure may be formed on the end surface of the top end of the support electrode 200 through a process of making a mask in photolithography and wet etching.
  • the sealing structure may have a plurality of protrusions 230 or recesses 230.
  • the protruding portion 230 or the recessed portion 230 appears as a sealing pattern in the top view angle of the end surface of the top end of the supporting electrode 200, the height of the protruding portion 230 relative to the end surface is controlled to be 1 ⁇ m or more, or the recessed portion 230 is opposite to The depth of the recess on the end surface is controlled to be above 1 ⁇ m, as shown in Figure 5D.
  • the seed layer formed in step S420 that is not removed in step S430 and is exposed to the outside of the substrate 110, it needs to be removed at this time.
  • the seed layer can be removed by a wet etching process.
  • the first seed layer and the second seed layer in the support electrode 200 may be formed correspondingly.
  • the support electrode 200 includes: a first support electrode 210 and a plurality of second support electrodes 220, the first support electrode 210 is outwardly protruding from the base 110 on the edge of the front surface of the base 110, and at the same time
  • the first supporting electrode 210 forms an annular closed structure around the edge of the front surface of the base 110; each second supporting electrode 220 of the plurality of second supporting electrodes 220 is arranged outwardly with respect to the base 110 and protruding from the front of the base 110.
  • the plurality of second supporting electrodes 220 are surrounded by the first supporting electrodes 210 in the middle of the front surface of the base 110.
  • the sealing structure includes: a first sealing structure and a plurality of second sealing structures, the first sealing structure is disposed on the end surface of the top end of the first supporting electrode 210; each second sealing structure of the plurality of second sealing structures corresponds to the Each second support electrode 220 in the two second support electrodes 220 is disposed on the end surface of the top end of each second support electrode 220 in the plurality of second support electrodes 220.
  • each second sealing structure of the first sealing structure and the plurality of second sealing structures includes a plurality of protruding portions 230 or recessed portions 230 correspondingly provided.
  • forming a thin film structure 300 spaced from the supporting electrode 200 on the base 110 includes:
  • a protective sealing film namely the film layer 310
  • the support electrode 200 can be used for support to form a resonance isolated from the outside.
  • Structural protection cavity 420 the film layer 310 may be a dry film.
  • the sealing pattern on the sealing structure can play a role of fixing and adhering on the front surface of the film layer 310 to facilitate the later curing and sealing of the film layer 310, as shown in FIGS. 7A and 7B.
  • the final protective sealing film layer 310 is formed through a high-temperature curing process, and the curing temperature is controlled at 250° C. or higher, so it can be compatible with the influence of the high temperature in the subsequent processing steps on the film layer 310.
  • the thickness of the film layer 310 after curing may be 10 ⁇ m to 60 ⁇ m, as shown in FIG. 7A and FIG. 7B.
  • 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 anchor portions above the support electrode 200 are formed by a photolithography process.
  • the plurality of through holes 410 may also be prepared by other processes such as laser; the anchor opening 440 may also be prepared by mechanical cutting or laser process, as shown in FIG. 7A and FIG. 7B.
  • each through hole 410 of the plurality of through holes 410 is correspondingly arranged and penetrated with 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 In the film layer 310; a plurality of anchor openings 440 are correspondingly disposed above the first support electrode 210 along the edge of the film layer 310.
  • forming a thin film structure 300 spaced from the supporting electrode 200 on the base 110 further includes:
  • a seed layer can be formed on the back surface of the film layer 310 with a plurality of through holes 410 and a plurality of anchor openings 440 formed by physical vapor deposition, and then photolithography and The wiring (RDL) electroplating technology prepares the lead electrode 320 and the anchor portion 350, and the thickness is controlled within 5 ⁇ m-40 ⁇ m, as shown in FIG. 9A and FIG. 2B.
  • RDL The wiring
  • the contact width of the anchor portion 350 and the first support electrode 210 is k ⁇ 10 ⁇ m
  • the length c is ⁇ 40 ⁇ m.
  • the anchor portion 350 may be a glue material or a metal material.
  • the distribution of the anchor portions 350 can be arranged along the first supporting electrode 210 to surround the device, and is not limited to anchoring a certain local area of the film layer 310.
  • the lead electrode 320 not only serves as an electrical interconnection between the device and the outside world (for example, flip-chip interconnection or lead interconnection, etc.), but can also enhance the strength of the film layer 310, and its coverage area should be expanded as much as possible to achieve Better heat dissipation effect.
  • the passivation layer 330 can be prepared on the back surface of the lead electrode 320 by a coating or chemical vapor deposition process, which can absorb the protection of the lead electrode 320, for example, to prevent the subsequent processing steps from causing damage to the lead electrode 320. Damage, as shown in Figure 9B.
  • an etching process such as photolithography can be used to form an outer surface of the lead electrode 320 corresponding to the upper end surface of the first support electrode 210 and the back surface of the film layer 310 to form an outer surface of the lead electrode 320.
  • the passivation layer 330 on the surface is etched to form a passivation hole 430 through the passivation layer 330 on the passivation layer 330 for contacting the back electrode 340 formed in the subsequent step with the lead electrode 320, That is, the electrical connection between the two is realized, as shown in Fig. 9B.
  • a flip-chip electrode contacting the outer surface of the lead electrode 320 may be formed at the position of the passivation hole 430 by an electroplating process, that is, the back electrode 340, and the height of the back electrode 340 is controlled to be 30 ⁇ m to 150 ⁇ m.
  • a metal seed layer may be formed on the back surface of the thin film structure formed with the passivation hole 430 by physical vapor deposition, and a back electrode 340 may be formed on the passivation hole 430 by using photolithography and electroplating processes, as shown in FIG. Shown at 9C.
  • each lead electrode 320 in the plurality of lead electrodes 320 is filled and arranged corresponding to each through hole 410 in the plurality of through holes 410, and each lead electrode 320 in the plurality of lead electrodes 320
  • the lower end of each of the plurality of second support electrodes 220 is in contact with the end surface of the top end of each second support electrode 220, and the upper end of each of the plurality of lead electrodes 320 is laid on the back surface of the film layer 310.
  • the inner surface of the upper end of each of the lead electrodes 320 is in contact with the back surface of the film layer 310; each of the plurality of anchor portions 350 is correspondingly disposed in each of the plurality of anchor openings 440.
  • Anchor opening 440 in.
  • Each passivation layer 330 of the plurality of passivation layers 330 corresponds to each of the plurality of lead electrodes 320 and is arranged on the outer surface of the upper end of each of the plurality of lead electrodes 320;
  • Each passivation hole 430 in the plurality of passivation holes 430 corresponds to each back electrode 340 of the plurality of back electrodes 340 and is opened on each passivation layer 330 of the plurality of passivation layers 330;
  • Each back electrode 340 of the electrodes 340 and each of the plurality of lead electrodes 320 are disposed on the outer surface of the upper end of each of the plurality of lead electrodes 320 corresponding to each lead electrode 320 of the plurality of lead electrodes 320, and are correspondingly disposed on the outer surface of the upper end of each lead electrode 320.
  • a support electrode 210 is directly above.
  • the present disclosure proposes a method for preparing a radio frequency filter.
  • the radio frequency filter includes a substrate, a supporting electrode, and a thin film structure.
  • the supporting electrode is protrudingly arranged on the front surface of the substrate; and the thin film structure is formed on the substrate with supporting electrodes at intervals.
  • the end surface of the top end of the supporting electrode is in sealing contact with the front surface of the film structure.
  • the preparation method of the radio frequency filter of the present disclosure overcomes the technical prejudice in the field in structure, and replaces the traditional protective wafer substrate with a thin film structure, so that the package of the radio frequency filter can be packaged through a simple film (corresponding to the Film layer) can realize effective packaging of the sealed cavity of the device, 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 cost of the device is greatly reduced, and the competitiveness of the device is improved;
  • the device structure of the present disclosure unexpectedly, it is possible to control the distribution area of the lead electrode on the back surface of the film layer, which can further improve the heat dissipation efficiency of the device; more importantly, it has achieved unexpected technical effects: the processing of packaged products The cycle is shortened by more than half, which can be said to be a milestone in the history of RF filter device research and development.

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Abstract

本公开提出了一种射频滤波器的制备方法，该射频滤波器包括：基体、支撑电极和薄膜结构，支撑电极凸设于基体的正表面；薄膜结构间隔支撑电极形成于基体上。支撑电极的顶端的端面与薄膜结构的正表面密封接触。

Description

射频滤波器的制备方法 技术领域
本公开涉及滤波器技术领域，尤其涉及一种射频滤波器的制备方法。
背景技术
随着5G技术不断发展，射频滤波器的应用与需求不断升级，对于射频滤波器的性能指标要求不断提高。根据声波的传递方式，射频滤波器通常分为：体声波滤波器和声表面波滤波器。其中，声表面波滤波器一般工作在2.5G频率以下，体声波滤波器工作在1.5G～10G频率。
无论是声表面波滤波器还是体声波滤波器，为了保持良好的射频性能指标，对其工作环境有一定的要求，需要制备一个相对密闭空腔(即保护腔)，用以隔绝外部的水气，颗粒，玷污等对器件的影响。常规做法是先制备一张保护性基体，该基体通常是硅，玻璃，陶瓷，金属外壳等，然后采用圆片级键合，焊接等工艺对滤波器进行隔离保护，再通过一系列复杂的流程加工而成，例如，为实现对体声波(Bulk acoustic wave，简称BAW)滤波器器件的保护腔的制备，可以采用以下一些材料、工艺和设备：1)双抛高阻硅片作为保护性基体；2)采用硅穿孔(TSV)和深孔电极填充技术进行通孔电极加工；3)采用材料金作为圆片键合和电极材料；4)需要价格高昂的圆片键合和具有侧向沉积能力的物理气相沉积设备。
因此，使得射频滤波器的整个制备工艺流程较长，工艺实现难度较高，同时，以上这些材料、工艺和设备的应用导致BAW器件的单颗制备成本昂贵，直接影响产品规模化应用和市场竞争力。
发明内容
本公开提出了一种射频滤波器的制备方法，包括：
在基体的正表面上形成谐振结构；
基于所述谐振结构在基体的正表面上形成支撑电极；以及
在所述基体上形成以所述支撑电极为间隔的薄膜结构。
根据本公开的实施例，所述基于所述谐振结构在基体的正表面上形成支撑电极，包括：
在基体的正表面上形成一层牺牲层；
在所述牺牲层上形成一层种子层；以及
基于所述谐振结构在所述种子层上形成所述支撑电极，
其中，所述支撑电极的顶端的端面与所述薄膜结构的正表面密封接触，所述支撑电极包括：
第一支撑电极，所述第一支撑电极相对所述基体向外凸设于所述基体的所述正表面的边缘，同时所述第一支撑电极围绕所述基体的正表面的边缘呈一环形封闭结构；
多个第二支撑电极，所述多个第二支撑电极中的每个第二支撑电极相对所述基体向外按一定分布凸设于所述基体的正表面的中部，同时所述多个第二支撑电极被所述第一支撑电极围绕在所述基体的正表面的中部。
根据本公开的实施例，所述基于所述谐振结构在所述种子层上形成所述支撑电极之后，还包括：
去除暴露于所述基体正表面上、支撑电极区域之外的种子层，形成对应支撑电极的第一种子层和多个第二种子层；
其中，所述第一种子层设置于所述第一支撑电极和所述基体之间；
所述多个第二种子层中的每个第二种子层相对设置于所述多个第二支撑电极中的每个第二支撑电极与所述基体之间；
其中，所述第一种子层和所述多个第二种子层中的每个第二种子层的材料为钛、钨、金、铜或上述金属之间的组合。
根据本公开的实施例，所述基于所述谐振结构在所述种子层上形成所述支撑电极之后，还包括：
在所述支撑电极的顶端的端面上形成密封结构；
所述密封结构包括：
第一密封结构，所述第一密封结构设置于所述第一支撑电极的顶端的端面上；
多个第二密封结构，所述多个第二密封结构中的每个第二密封结构对应于所述多个第二支撑电极中的每个第二支撑电极、设置于所述多个第二 支撑电极中的每个第二支撑电极的顶端的端面上；
其中，所述第一密封结构和所述多个第二密封结构的每个第二密封结构均包括对应设置的多个凸出部或凹陷部。
根据本公开的实施例，所述在所述基体上形成以所述支撑电极为间隔的薄膜结构，包括：
在所述具有支撑电极的基体上、对应所述支撑电极的顶端的端面上贴覆一层膜层，
对所述膜层进行固化，所述固化温度为T，T≥250℃；
其中，所述膜层间隔所述支撑电极设置于所述基体上，所述支撑电极的顶端的端面与所述膜层的正表面密封接触，其中，所述膜层被进行固化之后的厚度为m，10μm≤m≤60μm。
根据本公开的实施例，所述对所述膜层进行固化之后，包括：
在所述已固化的膜层上形成多个通孔和多个锚定开口；
其中，所述多个通孔中的每个通孔与所述多个第二支撑电极的每个第二支撑电极的顶端的端面的中间位置对应设置、并穿设于所述膜层；所述多个锚定开口沿所述膜层边缘对应设置于所述第一支撑电极的上方；
所述多个锚定开口沿所述膜层边缘对应设置于所述第一支撑电极的上方，所述锚定开口在所述膜层的背表面上的投射尺寸为长c，宽k，c≥40μm，k≥10μm。
根据本公开的实施例，所述在所述基体上形成以所述支撑电极为间隔的薄膜结构，还包括：
基于所述多个通孔和多个锚定开口在所述膜层的背表面上分别对应形成多个引电极和多个锚定部；
其中，所述多个引电极中的每个引电极与所述多个通孔中的每个通孔对应填充设置，所述多个引电极中的每个引电极的下端与所述多个第二支撑电极中的每个第二支撑电极的顶端的端面相接触，所述多个引电极中的每个引电极的上端铺设于所述膜层的背表面，所述多个引电极的每个引电极上端的内表面与所述膜层的背表面相接触；
所述多个锚定部中的每个锚定部对应设置于所述多个锚定开口中的每个锚定开口中，所述锚定部的厚度为d，5μm≤d≤40μm。
根据本公开的实施例，所述在所述基体上形成以所述支撑电极为间隔的薄膜结构，还包括：
在所述多个引电极上对应形成多个钝化层；
基于所述多个钝化层对应形成多个钝化孔；
其中，所述多个钝化层中的每个钝化层与所述多个引电极中的每个引电极对应、覆设于所述多个引电极中的每个引电极上端的外表面上；
所述多个钝化孔中的每个钝化孔与所述多个背电极中的每个背电极对应、开设于所述多个钝化层中的每个钝化层上。
根据本公开的实施例，所述在所述基体上形成以所述支撑电极为间隔的薄膜结构，还包括：
基于所述多个钝化孔对应形成多个背电极；
所述多个背电极中的每个背电极与所述多个引电极中的每个引电极相对应设置于所述多个引电极中的每个引电极的上端的外表面上，并对应设置于所述第一支撑电极的正上方。
根据本公开的实施例，所述基于所述谐振结构在基体的正表面上形成支撑电极，所述射频滤波器包括：
保护腔，所述保护腔为所述第一支撑电极、所述多个第二支撑电极和所述基体正表面之间的腔体空间；
其中，所述基体正表面与所述第一支撑电极顶端的端面之间的间距为j1，所述基体正表面与所述多个第二支撑电极中的每个第二支撑电极顶端的端面之间的间距为j2，10μm≤j1≤40μm，10μm≤j2≤40μm；Δj＝|j1－j2|，Δj≤10μm。
附图说明
图1A是根据本公开的一实施例中未覆盖薄膜结构的射频滤波器的内部立体示意图；
图1B是根据本公开的一实施例中对应图1A中已覆盖膜层的射频滤波器的外观立体示意图；
图1C是根据本公开的一实施例中对应图1B中具备锚定部和引电极的射频滤波器的外观立体示意图；
图2A是根据本公开的一实施例中对应图1C中B-B＇切线的具备背电极的射频滤波器的结构剖面示意图；
图2B是根据本公开的一实施例中对应图1C中A-A＇切线的射频滤波器的结构剖面示意图；
图3是根据本公开的一实施例中对应图2A和图2B中射频滤波器的制备流程示意图；
图4是根据本公开的一实施例中射频滤波器的一制备流程示意图；
图5A是根据本公开的一实施例中射频滤波器的一制备流程阶段的一结构示意图；
图5B是根据本公开的一实施例中射频滤波器的一制备流程阶段的另一结构示意图；
图5C是根据本公开的一实施例中射频滤波器的一制备流程阶段的又一结构示意图；
图5D是根据本公开的一实施例中射频滤波器的一制备流程阶段的再一结构示意图；
图6是根据本公开的一实施例中射频滤波器的另一制备流程示意图；
图7A是根据本公开的一实施例中射频滤波器的另一制备流程阶段的一结构示意图；
图7B是根据本公开的一实施例中射频滤波器的另一制备流程阶段的另一对应图1B中A-A＇切线的结构示意图；
图8是根据本公开的一实施例中射频滤波器的又一制备流程示意图；
图9A是根据本公开的一实施例中射频滤波器的又一制备流程阶段的一结构示意图；
图9B是根据本公开的一实施例中射频滤波器的又一制备流程阶段的另一结构示意图；
图9C是根据本公开的一实施例中射频滤波器的又一制备流程阶段的又一结构示意图。
具体实施方式
为使本公开的目的、技术方案和优点更加清楚明白，以下结合具体实 施例，并参照附图，对本公开进一步详细说明。
本公开的一个方面提出了一种射频滤波器，如图1A-1C，以及图2A-2B所示，包括：基体110、支撑电极200和薄膜结构300，
支撑电极200相对基体110向外凸设于基体110的正表面；
薄膜结构300间隔支撑电极200形成于基体110上，支撑电极200的顶端的端面与薄膜结构300的正表面密封接触。
根据本公开的实施例，对于本公开的射频滤波器，基体110可以是晶圆基体的全部或者部分，具体地，例如，当基体110是晶圆基体的全部时，则本公开的射频滤波器可以是一单独的射频滤波器的结构，当基体110是晶圆基体的部分时，则本公开的射频滤波器可以晶圆基体形成的射频滤波器的阵列结构中一单独器件结构。其中，晶圆基体可以是具有4寸、6寸、8寸面积尺寸的圆片级基体，该圆片级基体材质可以是硅、玻璃以及三五族半导体材料的材质，用于作为本公开的薄膜结构300的配合衬底。该基体110还可以用于提供支撑电极的形成衬底，同时为对应的射频滤波器的谐振结构形成保护空间。
为将基体110进行有效密封，同时形成对射频滤波器的谐振结构的保护作用，本公开提供了一形成于基体110正表面上的支撑电极200，该支撑电极200相对基体110向外凸设于基体110的正表面，可以与基体110一体成型。根据本公开的实施例，“正表面”以及后续的“背表面”仅仅是相对于谐振结构的所在位置进行定义的，即谐振结构所在的表面或朝向谐振结构的表面，在本公开中称为“正表面”，反之，称为“背表面”。
根据本公开的实施例，由于薄膜结构300的采用，支撑电极200材料可以采用铜、或类铜材料、类铜的合金材料等，极大地降低了成本。根本公开的实施例，由于铜、类铜材料或类铜合金材料的电阻率比金更低，有利于减小器件的插入损耗，益于在高温高压下金属原子的扩散，使得接触界面更加模糊，甚至相对于金材料，本公开的电极材料接触达到了比金材料接触更好的结合强度，以及更好的谐振效应和密封强度。类铜材料或类铜合金材料是指该材料特性与铜本身类似，例如电阻率接近。
薄膜结构300至少具有一膜层，通过覆膜的工艺直接贴覆在具有支撑电极200的基体110上。支撑电极用于起到对薄膜结构300的支撑作用， 以在薄膜结构300和基体110之间形成谐振结构的保护空间或谐振空间。为进一步有效的密封器件，本公开可以将密封结构设置于支撑电极的顶端的端面上，用于与薄膜结构300的膜层的正表面进行接触密封。
本公开在结构上克服了本领域中“采用薄膜结构300替代传统保护性晶圆基体”的技术偏见，通过膜层替代了传统的保护性晶圆基体，使得射频滤波器的封装通过简单的覆膜(对应于本公开的膜层)即可实现对器件密封腔的有效封装，制备流程大幅度缩短，生产效率提高，流程简单化；同时避免了金材料的使用，极大的降低了器件成本，提高器件竞争力；尤为重要的是，取得了预料不到的技术效果：封装产品的加工周期缩短一半以上，可以说是射频滤波器器件研发历史上里程碑式的进展。
为更好的对该射频滤波器的结构进行说明，以下参照图1A-1C，以及图2A-2B对本公开的射频滤波器结构进行详述。在此，本领域技术人员应当理解，在本公开“具体实施方式”中所提到的有关技术细节，绝非是对本公开保护范围的限定。
根据本公开的实施例，如图1A，以及图2A-2B所示，支撑电极200包括：第一支撑电极210、第一种子层、多个第二支撑电极220和多个第二种子层，第一支撑电极210相对基体110向外凸设于基体110的正表面的边缘，同时第一支撑电极围绕基体110的正表面的边缘呈一环形封闭结构；第一支撑电极210用于对薄膜结构300提供器件结构的边缘支撑作用，第一支撑电极210可以采用铜、或类铜材料、类铜的合金材料等形成，以降低材料成本。
根据本公开的实施例，如图1A，以及图2A-2B所示，第一种子层设置于第一支撑电极210和基体110之间；第一种子层用于在第一支撑电极210和基体110之间提供一过渡层的作用，以助于在第一支撑电极210下表面和基体110正表面之间增加金属层间粘附力，以提高界面接触上的金属原子扩散能力。
根据本公开的实施例，如图1A，以及图2A-2B所示，多个第二支撑电极220中的每个第二支撑电极220相对基体110向外按一定分布凸设于基体110的正表面的中部，同时多个第二支撑电极220被第一支撑电极210围绕在基体110的正表面的中部。一定分布可以是在基体110的正表面上、 第一支撑电极210围绕的空间内的均匀分布，以起到对膜层310的有效支撑，提高器件结构强度。第二支撑电极220用于对薄膜结构300提供器件结构的中部支撑作用，第二支撑电极220可以采用铜、或类铜材料、类铜的合金材料等形成，以降低材料成本。
根据本公开的实施例，如图1A，以及图2A-2B所示，多个第二种子层相对设置于多个第二支撑电极220中的每个第二支撑电极220与基体110之间；第二种子层用于在第二支撑电极220和基体110之间提供一过渡层的作用，以助于在第二支撑电极220下表面和基体110正表面之间增加金属层间粘附力，以提高界面接触上的金属原子扩散能力。
根据本公开的实施例，第一种子层和多个第二种子层中的每个第二种子层的材料为钛、钨、金、铜或上述金属之间的组合，例如钛钨加铜合金或钛钨加金合金等。
根据本公开的实施例，如图1A，以及图2A-2B所示，射频滤波器还包括：保护腔420，该保护腔130为上述的保护空间，用于为基体110上设置的谐振结构提供保护空间，同时还可以用于给谐振结构提供谐振作用空间。
根据本公开的实施例，如图1A，以及图2A-2B所示，保护腔420为第一支撑电极210、多个第二支撑电极220和基体110正表面之间的腔体空间；该保护腔420的形状可以根据第一支撑电极210和多个第二支撑电极220的配合进行相应设置，在本公开中不作限制。另外该保护腔420的主体空间(可以理解为对应谐振结构的空间)需要比其对应的谐振结构的尺寸略大。
根据本公开的实施例，如图1A，以及图2A-2B所示，基体110正表面与第一支撑电极210顶端的端面之间的间距为j1，基体110正表面与多个第二支撑电极220中的每个第二支撑电极220顶端的端面之间的间距为j2，10μm≤j1≤40μm，10μm≤j2≤40μm；Δj＝|j1－j2|，Δj≤10μm。该间距j1可以理解为第一支撑电极210的高度，该间距j2可以理解为第二支撑电极220的高度，其共同决定了该保护腔420相对于器件结构的深度。根据本公开的实施例，理想状态下，第一支撑电极210的高度j1和第二支撑电极220的高度j2应相等，即Δj＝0，由于支撑电极200的第一支撑 电极210和第二支撑电极220制备工艺(例如电镀工艺)、形成位置(中间或边缘)等差别，造成支撑电极200的整体高度越大，则Δj越大。而Δj≤10μm的设计，有利于薄膜结构300的膜层310在进行贴覆后，支撑电极200可以实现对膜层310更好的支撑作用，防止膜层310结构变形，结构更加平整。
根据本公开的实施例，如图1A，以及图2A所示，基体110包括：谐振结构和多个下电极层120，谐振结构对应于保护腔420设置于基体110正表面，用于产生器件的谐振效应。
根据本公开的实施例，如图1A，以及图2A所示，多个下电极层120中的每个下电极层120对应于多个第二支撑电极220中的每个第二支撑电极220的下表面、内凹于基体110的正表面，下电极层120材料为铜、金、钼、铝或上述金属之间的组合；通过下电极层120可以将基体110上的谐振结构与第二支撑电极220电性相连，同时第二支撑电极220还可以起到与下电极层120之间的电连接作用。
根据本公开的实施例，如图1A，以及图2A-2B所示，谐振结构至少包括：压电层130，压电层130对应于保护腔420设置于基体110正表面，用于起到一定的谐振功能，以助于谐振效应的实现。同时，根据本公开的实施例，谐振结构还可以包括谐振腔，谐振腔可以是位于压电层下方、内凹于基体110正表面的内凹空间，压电层此时还可以用于封闭谐振腔。
根据本公开的实施例，如图1A-图2B所示，基体110还包括：多个间隔层，多个间隔层中的每个间隔层对应于多个下电极层120中的每个下电极层120的下表面、设置于多个下电极层120中的每个下电极层120和基体110之间，间隔层用于在下电极层120和基体110之间提供一过渡层的作用，以助于在下电极层120外表面和基体110之间增加金属层间粘附力，以提高界面接触上的金属原子扩散能力。根据本公开的实施例，间隔层的材料为钛、钨、镍、铬或上述金属之间的组合。
根据本公开的实施例，如图1B-图1C，图2A所示，薄膜结构包括：膜层310、多个通孔410、多个引电极320和多个背电极340，其中，膜层310间隔支撑电极200设置于基体110上，支撑电极200的顶端的端面与膜层310的正表面密封接触。膜层的厚度为m，10μm≤m≤60μm。膜 层310是薄膜结构300的主体结构，可以是干膜类薄膜，通过对其进行固化工艺，即可以替代传统高温高压的键合方案，实现器件密封。该膜层310在固化前后膜厚会产生一定变化，具体地，膜层310固化之后的厚度m可以是固化之前的厚度m＇的20％-50％。另外，该膜层310可以是圆片级覆膜结构的全部或部分。
因此，本公开采用膜层310创造性地替代传统的晶圆基体作为保护层，同时实现了膜层310与基体110之间的器件封装工艺，成本更低，器件更易于加工，是本领域中的首创。在结构上克服了本领域对“薄膜膜层作为保护层”的技术偏见，通过薄膜结构300替代了传统的保护性晶圆基体110，使得射频滤波器的封装通过简单的覆膜即可实现对器件密封腔的有效封装，制备流程大幅度缩短，生产效率提高，流程简单化；同时避免了金材料的使用，极大的降低了器件成本，提高器件竞争力；尤为重要的是，取得了预料不到的技术效果：封装产品的加工周期缩短一半以上，不再需要深硅刻蚀、深孔溅射、高温高压键合等流程及相应设备，极大地提高了制备效率，节约了制备时间和制备成本，封装投产成本大幅下降，可以说是射频滤波器器件研发历史上里程碑式的进展。
根据本公开的实施例，如图1B-图1C，图2A所示，多个通孔410中的每个通孔410与多个第二支撑电极220的每个第二支撑电极220的顶端的端面的中间位置对应设置、并穿设于膜层310；通孔410用于为引电极320提供一定的填充空间和固定位置，有利于引电极320在膜层310背表面上的分布更加规整可控。
根据本公开的实施例，如图1B-图1C，图2A所示，多个引电极320中的每个引电极320与多个通孔410中的每个通孔410对应填充设置，多个引电极320中的每个引电极320的下端与多个第二支撑电极220中的每个第二支撑电极220的顶端的端面相接触，多个引电极320中的每个引电极320的上端铺设于膜层310的背表面，多个引电极320的每个引电极320上端的内表面与膜层310的背表面相接触，其中，多个引电极320中的每个引电极320的位于膜层310的背表面的上端的厚度为y，5μm≤m≤40μm。引电极320下端部分填充于通孔410中，引电极320下端部分的下表面与第二支撑电极220的顶端端面密封接触，在第二支撑电极220的下 表面与基体110上的下电极层120相电连接接触的情况下，引电极320用于实现将器件下电极层与外部相连。
根据本公开的实施例，如图1B-图1C，图2A所示，该引电极320的上端部分平铺于膜层310的背表面上，并优先铺设于第二支撑电极220和第一支撑电极210之间的对应膜层310的背表面区域上。膜层310的背表面的面积为s1，多个引电极320中的每个引电极320的上端部分在膜层310的背表面的分布面积为s2，分布在膜层310背表面的多个引电极320的分布数量为n，Δs＝(n×s2)/s1，Δs≥0.2。Δs的值越接近于1，该引电极320的上端部分在膜层310背表面的覆盖区域面积越大，则引电极320还可以用于以提高膜层310的结构强度，同时增加器件的整体散热效率。其中，引电极320的材料可以是铜等金属。在本公开的器件结构中，意外可以实现引电极在膜层背表面的分布面积的控制，可以进一步提高器件散热效率。
根据本公开的实施例，如图1B-图1C，图2A所示，多个背电极340中的每个背电极340与多个引电极320中的每个引电极320相对应设置于多个引电极320中的每个引电极320的上端的外表面上，并对应设置于第一支撑电极210的正上方，第一支撑电极210可以用于同时实现对膜层310和其背表面上的背电极340的支撑作用。其中，背电极340的高度为b，30μm≤b≤150μm，背电极340的下表面连接于引电极320的外表面，背电极340可以用于实现器件结构与外界的电连接。
根据本公开的实施例，如图2A所示，薄膜结构300还包括：多个钝化层330和多个钝化孔430，多个钝化层330中的每个钝化层330与多个引电极320中的每个引电极320对应、覆设于多个引电极320中的每个引电极320上端的外表面上。钝化层330可以起到保护引电极320的作用(例如后续工艺中的损伤)，以增加器件可靠性，钝化层330需要能够完整覆盖引电极320；钝化层330的材料可以是介质类材料或胶质材料。
根据本公开的实施例，如图2A所示，多个钝化孔430中的每个钝化孔430与多个背电极中的每个背电极340对应、开设于多个钝化层330中的每个钝化层330上。钝化孔430用于将钝化层330打通，同时为背电极340形成于引电极320上端部分的外表面提供空间，使得背电极340可以 与引电极320实现电连接。
根据本公开的实施例，根据本公开的实施例，如图1B-图1C，图2B所示，薄膜结构300还包括：多个锚定开口440和多个锚定部350，多个锚定开口440沿膜层310边缘对应设置于第一支撑电极210的上方，锚定开口440在膜层310的背表面上的投射尺寸为长c，宽k，c≥40μm，k≥10μm，具体如图1B所示；c、k值越大，锚定开口440将决定锚定部350与膜层310和接触面积越大，使得锚定开口440用于为锚定部350提供锚定位置，以利于将膜层310更好的密封在基体110上。锚定开口440的底表面为第一支撑电极210的上表面，即，膜层310的厚度为锚定开口440的高度。其中，c、k值可以根据第一支撑电极210的尺寸设定。
根据本公开的实施例，根据本公开的实施例，如图1B-图1C，图2B所示，多个锚定部350中的每个锚定部350对应设置于多个锚定开口440中的每个锚定开口440中，锚定部350的厚度为d，5μm≤d≤40μm。锚定部350的材料可以是金属，以起到对膜层310强度的提高，同时用于增强膜层310与第一支撑电极210之间的密封性，在经过固化工艺后，使得膜层能够借助锚定部350达到一定的强度和抗腐蚀性，以进一步增强器件的可靠性和稳固性，同时增加器件的强度，延长器件寿命。
根据本公开的实施例，根据本公开的实施例，如图1B-图1C，图2B所示，多个锚定部350的每个锚定部350可以为一L型设计，包括：锚定部350上端的锚端和锚定部350下端的定端，L型设计更有利于锚定部350实现锚定带来的密封效果和强度增强效益。根据本公开的实施例，锚端对应设置于锚定开口440中；其厚度d可以是锚定部350锚定于膜层310背表面边缘的锚端的厚度，锚端用于实现对膜层310背表面提供自上而下的锚定力，以助于锚定效果。根据本公开的实施例，定端对应设置于膜层的背表面上，其厚度d可以是锚定部350锚定于膜层310侧表面、第一支撑电极210上表面上的锚定开口中的定端的宽度，相当于上述的k值。顶端用于实现在膜层310的侧表面和第一支撑电极层210之间提供自下而上、自外而内的锚定力，以助于实现锚定效果。
根据本公开的实施例，如图2A所示，支撑电极200还包括密封结构，密封结构用于给膜层310进行贴覆时、未进行固化工艺之前(此时膜层310 的正表面具有一定粘附力，以利于在配合密封结构实现密封)，在膜层310的正表面上形成与密封结构之间的密封接触，在固化工艺之后，膜层310的正表面将通过密封结构完成对器件结构的密封。
根据本公开的实施例，如图2A所示，密封结构包括：第一密封结构和多个第二密封结构，第一密封结构设置于第一支撑电极210的顶端的端面上；用于第一支撑电极210和膜层310正表面之间的密封，以实现器件的外围封装。多个第二密封结构中的每个第二密封结构对应于多个第二支撑电极中的每个第二支撑电极、设置于多个第二支撑电极中的每个第二支撑电极的顶端的端面上；用于多个第二支撑电极220和膜层310正表面之间的密封，以实现器件的内部封装。
根据本公开的实施例，如图2A所示，第一密封结构和多个第二密封结构的每个第二密封结构均包括对应设置的多个凸出部或凹陷部，凸出部的高度为t，凹陷部的深度为a，t≥1μm，a≥1μm。凸出部或凹陷部的设计，将更加有利于在膜层310的贴覆-固化工艺过程中，实现第一密封结构和第二密封结构与膜层310正表面之间的固定(例如防止滑脱、错位等)、连接和密封。
本公开的另一个方面提出了一种制备方法，如图3所示，用于制备上述的射频滤波器，包括：
S310：在基体110的正表面上形成谐振结构；具体地，可以在基体110的正表面上形成谐振结构的压电层130、下电极层120等，以形成射频滤波器的谐振效应的基本结构。
S320：基于谐振结构在基体110的正表面上形成支撑电极200；具体地，可以在基体110的正表面上形成基于支撑电极200的谐振结构保护腔。该支撑电极200的制备可以是在基体110的正表面上依据掩模图案进行电镀来实现，以加强支撑电极200与基体110正表面之间的接触强度。
S330：在基体110上形成以支撑电极200为间隔的薄膜结构300，支撑电极200的顶端的端面与薄膜结构300的正表面密封接触。具体地，薄膜结构300的膜层310可以通过贴覆-固化的工艺固定密封在支撑电极200的顶端的端面上，实现器件的封装。
为便于本领域技术人员的理解，以下具体实施方式的描述部分，为减少重复，重点对制备方法和工艺进行解释，具体结构描述请以上述具体实施方法作为参考，在此不再赘述。
根据本公开的实施例，如图4所示，基于谐振结构在基体110的正表面上形成支撑电极200，包括：
S410：在基体110的正表面上形成一层牺牲层140；
根据本公开的实施例，在基体110上形成谐振结构以及下电极层120，其中谐振结构至少包括形成于基体110正表面上的压电层130，以完成对基体110的准备工作。在必要的情况下，需要在压电层130的下方制备一被压电层130封闭的谐振腔，例如体声波射频滤波器的制备(对应于只有压电层130的声表面射频滤波器)，如图5A所示。
根据本公开的实施例，在制备完成谐振结构和下电极层120的基体110正表面沉积一层工艺保护性的牺牲层140，厚度约为
Figure PCTCN2020073258-appb-000001
-1μm之间，牺牲层140的材料可以是氧化硅。牺牲层可以保护后续工艺步骤中不会损伤基体110。然后，基于基体110正表面上的谐振结构和下电极层120作为掩模图案，对牺牲层140进行刻蚀(例如光刻)或其他工艺，实现支撑电极200相对基体110正表面的形成支撑电极开口150，如图5B所示。
根据本公开的实施例，牺牲层140需要在后续的工艺过程中去除，当射频滤波器如果是体声波滤波器，谐振腔牺牲层的去除需要在支撑电极200制备之后进行，以避免影响谐振腔牺牲层的去除。
S420：在牺牲层140上形成一层种子层；
根据本公开的实施例，在基体110的正表面可以通过物理气相沉积方法形成一层种子层，种子层为金属层，种子层的材料可以是钛、钨、金、铜或上述金属之间的组合，例如钛钨加铜合金材料，或钛钨加金合金材料。种子层可以助于在支撑电极200下表面和基体110正表面之间增加金属层间粘附力，以提高界面接触上的金属原子扩散能力。
S430：基于谐振结构在种子层上形成支撑电极200，
根据本公开的实施例，可以通过光刻加电镀的工艺制备支撑电极200；支撑电极200的材料可以采用铜、或类铜材料、类铜的合金材料等。此时，上述步骤S420中形成的暴露于基体110正表面上、支撑电极200区域之 外的种子层可以选择去除，此时，只留下支撑电极200和基体110正表面之间的种子层，即对应于上述支撑电极200的第一种子层和第二种子层，如图5C所示。
S440：在支撑电极200的顶端的端面上形成密封结构；
根据本公开的实施例，可以通过在光刻制作掩模和湿法腐蚀的工艺在支撑电极200的顶端的端面上形成密封结构，密封结构可以具有多个凸出部230或凹陷部230，该凸出部230或凹陷部230在对支撑电极200的顶端的端面的俯视角度上表现为密封图案，该凸出部230相对于端面的凸出的高度控制在1μm以上，或凹陷部230相对于端面的凹陷的深度控制在1μm以上，如图5D所示。
需要说明的是，若在步骤S430中未能去除的步骤S420中形成的暴露于基体110外部的种子层，需要此时进行去除。具体可以通过湿法腐蚀工艺去除种子层。此时，对应可以形成位于支撑电极200中的第一种子层和第二种子层。
其中，参照图1A-图2B，支撑电极200包括：第一支撑电极210和多个第二支撑电极220，第一支撑电极210相对基体110向外凸设于基体110的正表面的边缘，同时第一支撑电极210围绕基体110的正表面的边缘呈一环形封闭结构；多个第二支撑电极220中的每个第二支撑电极220相对基体110向外按一定分布凸设于基体110的正表面的中部，同时多个第二支撑电极220被第一支撑电极210围绕在基体110的正表面的中部。
密封结构包括：第一密封结构和多个第二密封结构，第一密封结构设置于第一支撑电极210的顶端的端面上；多个第二密封结构中的每个第二密封结构对应于多个第二支撑电极220中的每个第二支撑电极220、设置于多个第二支撑电极220中的每个第二支撑电极220的顶端的端面上。其中，第一密封结构和多个第二密封结构的每个第二密封结构均包括对应设置的多个凸出部230或凹陷部230。
根据本公开的实施例，如图6所示，在基体110上形成以支撑电极200为间隔的薄膜结构300，包括：
S610：在具有支撑电极200的基体110上、对应支撑电极200的顶端的端面上贴覆一层膜层310，
根据本公开的实施例，可以通过圆片级贴膜的工艺在具有支撑电极200的基体110上整面贴上保护性密封薄膜，即膜层310，通过支撑电极200进行支撑形成与外部隔离的谐振结构的保护腔420。其中，该膜层310可以是干膜。此时，密封结构上的密封图案可以在膜层310的正表面上起到固定粘附作用，以利于膜层310后期的固化密封，如图7A、图7B所示。
S620：对膜层进行固化，固化温度为T，T≥250℃；
根据本公开的实施例，并通过高温固化的工艺，形成最终的保护性密封膜层310，固化温度控制在250℃以上，因此可以兼容后续加工步骤的高温对膜层310的影响。固化之后的膜层310的厚度可以在10μm～60μm，如图7A、图7B所示。
S630：在已固化的膜层310上形成多个通孔410和多个锚定开口440；
根据本公开的实施例，通过光刻工艺形成支撑电极200上方用于填充引电极320的多个通孔410和用于对应形成多个锚定部的多个锚定开口440。其中，多个通孔410也可以通过激光等其它工艺制备形成；锚定开口440也可以通过机械切割或者激光的工艺制备，如图7A、图7B所示。
其中，参照图1A-图2B，多个通孔410中的每个通孔410与多个第二支撑电极220的每个第二支撑电极220的顶端的端面的中间位置对应设置、并穿设于膜层310；多个锚定开口440沿膜层310边缘对应设置于第一支撑电极210的上方。
根据本公开的实施例，如图8所示，在基体110上形成以支撑电极200为间隔的薄膜结构300，还包括：
S810：基于多个通孔410和多个锚定开口440在膜层310的背表面上分别对应形成多个引电极320和多个锚定部350；
根据本公开的实施例，可以在形成了多个通孔410和多个锚定开口440的薄膜结构的膜层310的背表面上，通过物理气相沉积形成一层种子层，再采用光刻和布线(RDL)电镀技术的工艺制备引电极320和锚定部350，厚度控制在5μm～40μm，如图9A和图2B所示。其中，锚定部350与第一支撑电极210的接触宽度k≥10μm，长度c≥40μm。锚定部350可以是胶类材料或金属材料。为提高保护性密封薄膜的密封性，锚定部350的分布可以沿第一支撑电极210对器件进行周设，并不仅限于对膜层310 的某一局部区域的锚定。另外，引电极320不仅起到器件与外界的电性互连作用(例如倒装互连或引线互连等)，还可以加强膜层310的强度，其覆盖区域应尽可能的扩大，以实现更好的散热效果。
S820：基于多个引电极320上对应形成多个钝化层330；
根据本公开的实施例，可以通过涂覆或化学气相沉积的工艺在引电极320背表面上制备钝化层330，可以是吸纳对引电极320的保护，例如避免后续加工步骤对引电极320造成损伤，如图9B所示。
S830：基于多个钝化层330对应形成多个钝化孔430；
根据本公开的实施例，可以通过光刻等刻蚀工艺在对应于第一支撑电极210的上端面、膜层310背表面上的引电极320的外表面位置上，对形成于引电极320外表面上的钝化层330进行刻蚀，以在钝化层330上形成穿设于钝化层330的钝化孔430，用于将后续步骤中形成的背电极340与引电极320实现接触，即实现两者之间的电连接，如图9B所示。
S840：基于多个钝化孔430对应形成多个背电极340；
根据本公开的实施例，可以通过电镀的工艺在上述钝化孔430的位置形成与引电极320的外表面相接触的倒装电极，即背电极340，其高度控制在30μm～150μm。具体地，可以在通过物理气相沉积在形成有钝化孔430的薄膜结构的背表面上形成一层金属种子层，采用光刻和电镀的工艺在钝化孔430上形成背电极340，如图9C所示。
其中，参照图1A-图2B，多个引电极320中的每个引电极320与多个通孔410中的每个通孔410对应填充设置，多个引电极320中的每个引电极320的下端与多个第二支撑电极220中的每个第二支撑电极220的顶端的端面相接触，多个引电极320中的每个引电极320的上端铺设于膜层310的背表面，多个引电极320的每个引电极320上端的内表面与膜层310的背表面相接触；多个锚定部350中的每个锚定部350对应设置于多个锚定开口440中的每个锚定开口440中。多个钝化层330中的每个钝化层330与多个引电极320中的每个引电极320对应、覆设于多个引电极320中的每个引电极320上端的外表面上；多个钝化孔430中的每个钝化孔430与多个背电极340中的每个背电极340对应、开设于多个钝化层330中的每个钝化层330上；多个背电极340中的每个背电极340与多个引电极320 中的每个引电极320相对应设置于多个引电极320中的每个引电极320的上端的外表面上，并对应设置于第一支撑电极210的正上方。
本公开提出了一种射频滤波器的制备方法，该射频滤波器包括：基体、支撑电极和薄膜结构，支撑电极凸设于基体的正表面；薄膜结构间隔支撑电极形成于基体上。支撑电极的顶端的端面与薄膜结构的正表面密封接触。本公开的射频滤波器的制备方法在结构上克服了本领域的技术偏见，通过薄膜结构替代了传统的保护性晶圆基体，使得射频滤波器的封装通过简单的覆膜(对应于本公开的膜层)即可实现对器件密封腔的有效封装，制备流程大幅度缩短，生产效率提高，流程简单化；同时避免了金材料的使用，极大的降低了器件成本，提高器件竞争力；另外，在本公开的器件结构中，意外可以实现引电极在膜层背表面的分布面积的控制，可以进一步提高器件散热效率；尤为重要的是，取得了预料不到的技术效果：封装产品的加工周期缩短一半以上，可以说是射频滤波器器件研发历史上里程碑式的进展。
以上所述的具体实施例，对本公开的目的、技术方案和有益效果进行了进一步详细说明，所应理解的是，以上所述仅为本公开的具体实施例而已，并不用于限制本公开，凡在本公开的精神和原则之内，所做的任何修改、等同替换、改进等，均应包含在本公开的保护范围之内。

Claims (10)

  1. 一种射频滤波器的制备方法，其特征在于，包括：
    在基体的正表面上形成谐振结构；
    基于所述谐振结构在基体的正表面上形成支撑电极；以及
    在所述基体上形成以所述支撑电极为间隔的薄膜结构。
  2. 根据权利要求1所述的制备方法，其特征在于，所述基于所述谐振结构在基体的正表面上形成支撑电极，包括：
    在基体的正表面上形成一层牺牲层；
    在所述牺牲层上形成一层种子层；以及
    基于所述谐振结构在所述种子层上形成所述支撑电极，
    其中，所述支撑电极的顶端的端面与所述薄膜结构的正表面密封接触，所述支撑电极包括：
    第一支撑电极，所述第一支撑电极相对所述基体向外凸设于所述基体的所述正表面的边缘，同时所述第一支撑电极围绕所述基体的正表面的边缘呈一环形封闭结构；
    多个第二支撑电极，所述多个第二支撑电极中的每个第二支撑电极相对所述基体向外按一定分布凸设于所述基体的正表面的中部，同时所述多个第二支撑电极被所述第一支撑电极围绕在所述基体的正表面的中部。
  3. 根据权利要求2所述的制备方法，其特征在于，所述基于所述谐振结构在所述种子层上形成所述支撑电极之后，还包括：
    去除暴露于所述基体正表面上、支撑电极区域之外的种子层，形成对应支撑电极的第一种子层和多个第二种子层；
    其中，所述第一种子层设置于所述第一支撑电极和所述基体之间；
    所述多个第二种子层中的每个第二种子层相对设置于所述多个第二支撑电极中的每个第二支撑电极与所述基体之间；
    其中，所述第一种子层和所述多个第二种子层中的每个第二种子层的材料为钛、钨、金、铜或上述金属之间的组合。
  4. 根据权利要求2所述的制备方法，其特征在于，所述基于所述谐振结构在所述种子层上形成所述支撑电极之后，还包括：
    在所述支撑电极的顶端的端面上形成密封结构；
    所述密封结构包括：
    第一密封结构，所述第一密封结构设置于所述第一支撑电极的顶端的端面上；
    多个第二密封结构，所述多个第二密封结构中的每个第二密封结构对应于所述多个第二支撑电极中的每个第二支撑电极、设置于所述多个第二支撑电极中的每个第二支撑电极的顶端的端面上；
    其中，所述第一密封结构和所述多个第二密封结构的每个第二密封结构均包括对应设置的多个凸出部或凹陷部。
  5. 根据权利要求2所述的制备方法，其特征在于，所述在所述基体上形成以所述支撑电极为间隔的薄膜结构，包括：
    在所述具有支撑电极的基体上、对应所述支撑电极的顶端的端面上贴覆一层膜层，
    对所述膜层进行固化，所述固化温度为T，T≥250℃；
    其中，所述膜层间隔所述支撑电极设置于所述基体上，所述支撑电极的顶端的端面与所述膜层的正表面密封接触，其中，所述膜层被进行固化之后的厚度为m，10μm≤m≤60μm。
  6. 根据权利要求5所述的制备方法，其特征在于，所述对所述膜层进行固化之后，包括：
    在所述已固化的膜层上形成多个通孔和多个锚定开口；
    其中，所述多个通孔中的每个通孔与所述多个第二支撑电极的每个第二支撑电极的顶端的端面的中间位置对应设置、并穿设于所述膜层；所述多个锚定开口沿所述膜层边缘对应设置于所述第一支撑电极的上方；
    所述多个锚定开口沿所述膜层边缘对应设置于所述第一支撑电极的上方，所述锚定开口在所述膜层的背表面上的投射尺寸为长c，宽k，c≥40μm，k≥10μm。
  7. 根据权利要求6所述的制备方法，其特征在于，所述在所述基体上形成以所述支撑电极为间隔的薄膜结构，还包括：
    基于所述多个通孔和多个锚定开口在所述膜层的背表面上分别对应形成多个引电极和多个锚定部；
    其中，所述多个引电极中的每个引电极与所述多个通孔中的每个通孔 对应填充设置，所述多个引电极中的每个引电极的下端与所述多个第二支撑电极中的每个第二支撑电极的顶端的端面相接触，所述多个引电极中的每个引电极的上端铺设于所述膜层的背表面，所述多个引电极的每个引电极上端的内表面与所述膜层的背表面相接触；
    所述多个锚定部中的每个锚定部对应设置于所述多个锚定开口中的每个锚定开口中，所述锚定部的厚度为d，5μm≤d≤40μm。
  8. 根据权利要求7所述的制备方法，其特征在于，所述在所述基体上形成以所述支撑电极为间隔的薄膜结构，还包括：
    在所述多个引电极上对应形成多个钝化层；
    基于所述多个钝化层对应形成多个钝化孔；
    其中，所述多个钝化层中的每个钝化层与所述多个引电极中的每个引电极对应、覆设于所述多个引电极中的每个引电极上端的外表面上；
    所述多个钝化孔中的每个钝化孔与所述多个背电极中的每个背电极对应、开设于所述多个钝化层中的每个钝化层上。
  9. 根据权利要求8所述的制备方法，其特征在于，所述在所述基体上形成以所述支撑电极为间隔的薄膜结构，还包括：
    基于所述多个钝化孔对应形成多个背电极；
    所述多个背电极中的每个背电极与所述多个引电极中的每个引电极相对应设置于所述多个引电极中的每个引电极的上端的外表面上，并对应设置于所述第一支撑电极的正上方。
  10. 根据权利要求2所述的制备方法，其特征在于，所述基于所述谐振结构在基体的正表面上形成支撑电极，所述射频滤波器包括：
    保护腔，所述保护腔为所述第一支撑电极、所述多个第二支撑电极和所述基体正表面之间的腔体空间；
    其中，所述基体正表面与所述第一支撑电极顶端的端面之间的间距为j1，所述基体正表面与所述多个第二支撑电极中的每个第二支撑电极顶端的端面之间的间距为j2，10μm≤j1≤40μm，10μm≤j2≤40μm；Δj＝|j1－j2|，Δj≤10μm。
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