CN111431499A - Preparation method of flexible shear wave film bulk acoustic wave filter - Google Patents
Preparation method of flexible shear wave film bulk acoustic wave filter Download PDFInfo
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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
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/03—Assembling devices that include piezoelectric or electrostrictive parts
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N30/00—Piezoelectric or electrostrictive devices
- H10N30/01—Manufacture or treatment
- H10N30/07—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
- H10N30/072—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by laminating or bonding of piezoelectric or electrostrictive bodies
-
- 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
- H03H2003/023—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 the resonators or networks being of the membrane type
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
The invention discloses a preparation method of a flexible shear wave film bulk acoustic wave filter, which comprises the steps of depositing a piezoelectric layer on the upper end surface of a first substrate, growing an entire insulating protection layer on the piezoelectric layer and carrying out graphical etching to obtain a first composite substrate, preparing a temporary bonding layer on the upper end surface of a second substrate, and bonding a flexible substrate on the temporary bonding layer to obtain a second composite substrate; bonding the second composite substrate with the first composite substrate, peeling off the first substrate after bonding is finished to expose the piezoelectric layer, preparing a top electrode on the piezoelectric layer, and carrying out graphical processing on the top electrode; covering a top electrode on the piezoelectric layer to prepare a flexible protection layer, and simultaneously carrying out patterned photoetching on the flexible protection layer to expose the top electrode to form an upper cavity; debonding the second substrate from the flexible substrate to realize stripping, and obtaining a flexible filter device; and cascading a plurality of flexible filter devices to obtain the filter with the function of filtering different frequency bands.
Description
Technical Field
The invention relates to the technical field of filters, in particular to a preparation method of a flexible shear wave film bulk acoustic wave filter.
Background
Flexible electronics offer advantages over traditional rigid electronics in terms of weight, volume and portability, and have generated a great deal of interest in their applications, such as portable displays, electronic skins and wearable medical treatments. Wireless data exchange for flexible electronics has attracted extensive research interest in recent years. One such implementation is to integrate a rigid silicon chip onto a flexible circuit board, but this severely reduces the flexibility of the system. In the field of portable wearable flexible communication equipment, a high-performance miniaturized flexible radio frequency filter is used as a key component of a radio frequency wireless communication system, and the research of the high-performance miniaturized flexible radio frequency filter has a certain significance but is less.
Disclosure of Invention
The invention aims to provide a preparation method of a flexible XBAR filter, which can fill the blank of the prior art and realize the flexibility of the XBAR filter which is a key device in a radio frequency front-end module.
The invention is realized by the following technical scheme:
a method for preparing a flexible shear wave film bulk acoustic wave filter comprises the following steps:
step (1), taking a first substrate as a preparation substrate of a piezoelectric film, depositing a piezoelectric layer on the upper end surface of the first substrate, then growing an entire insulating protective layer on the piezoelectric layer, and carrying out patterned etching on the insulating protective layer to obtain a first composite substrate for later use;
taking the second substrate as a bonding substrate, preparing a temporary bonding layer on the upper end face of the second substrate, and bonding a layer of flexible substrate on the temporary bonding layer to obtain a second composite substrate;
bonding the second composite substrate with the first composite substrate, peeling off the first substrate after bonding is finished to expose the piezoelectric layer, preparing a top electrode on the piezoelectric layer, and carrying out graphical processing on the top electrode;
step (4), covering a top electrode on the piezoelectric layer to prepare a flexible protection layer, simultaneously carrying out patterned photoetching on the flexible protection layer, and etching the flexible protection layer above the middle part of the piezoelectric layer and the top electrode to expose the top electrode to form an upper cavity; debonding the second substrate from the flexible substrate to realize stripping, and obtaining a flexible filter device;
and (5) cascading a plurality of flexible filter devices to obtain the filter with the function of filtering different frequency bands.
Further, in the step (1) and the step (2), the first substrate and the second substrate are made of a silicon substrate, a sapphire substrate, a silicon carbide substrate, a gallium nitride substrate, an aluminum nitride substrate, or AlxGa1-xN buffer layer substrate, glass, plastic, gallium arsenide, steel, paper, silk, plastic, polyimide, parylene, polycarbonate, polyester resin, polyethylene naphthalate, polyethersulfone, polyetherimide, polydimethylsiloxane, polyvinyl alcohol or fluoropolymer.
Further, in the step (1), the piezoelectric layer is a single crystal piezoelectric film grown by epitaxy, or a high C-axis oriented polycrystalline piezoelectric film grown by sputtering, or AlN, ZnO, PZT, L iNbO3L iTaO 3.
Further, in the step (3), the top electrode is one or two of graphene, gold, tungsten, molybdenum, platinum, ruthenium, iridium, germanium, copper, titanium tungsten, aluminum, chromium, or arsenic alloy, and the thickness of the top electrode is 1-500 nm.
Further, in the step (1), the insulating protection layer is made of one of SiO2, AlN, SiN, Si, plastic, polyimide, parylene, polycarbonate, polyester resin, polyethylene naphthalate, polyethersulfone, polyetherimide, polydimethylsiloxane, polyvinyl alcohol, or fluoropolymer.
Further, in the step (4), the material of the flexible protection layer is one of polyimide, parylene, polycarbonate, polyester resin, polyethylene naphthalate, polyethersulfone, polyetherimide, polydimethylsiloxane, polyvinyl alcohol, or fluoropolymer.
Further, in the step (3), the top electrode has a rectangular shape, an interdigital electrode shape, or a spiral overlapping shape.
Furthermore, the number of the flexible filter devices is changed and a cascading mode is adopted to prepare the XBAR filter which can cover the whole communication frequency band at any frequency.
Further, in the step (1), the first substrate is used for preparing the piezoelectric layer by an epitaxial growth or a lift-off method.
Further, in the step (3), the top electrode is prepared on the piezoelectric layer through an electron beam evaporation and lift-off process or a magnetron sputtering and patterning etching process.
The invention has the beneficial effects that:
the invention can omit a sacrificial layer and a CMP polishing process, has simple processing process, and greatly reduces the processing difficulty and the production cost of the flexible XBAR filter and improves the preparation yield of the flexible device because the adopted organic polymer insulating material has the advantages of simple preparation method, low material cost and easy operation in the wafer processing process.
Drawings
FIG. 1 is a cross-sectional view of a flexible XBAR resonator provided by an embodiment;
FIG. 2 is a schematic diagram illustrating a structure of a piezoelectric layer formed on a first substrate according to an embodiment;
FIG. 3 is a schematic diagram illustrating a structure of an insulating protection layer formed on a piezoelectric layer according to an embodiment;
FIG. 4 is a schematic structural view of a composite substrate obtained by preparing a flexible substrate on a second substrate in the example;
FIG. 5 is a schematic view illustrating bonding of a first composite substrate with a second composite substrate according to an embodiment;
FIG. 6 is a schematic view showing a structure in which the first substrate is peeled off in the embodiment;
FIG. 7 is a schematic view of an electrode prepared and patterned in the examples;
FIG. 8 is a schematic diagram of preparing a top flexible passivation layer and etching away the flexible passivation layer on the active region, and then debonding and peeling off the hard substrate in the example;
FIG. 9 is a schematic diagram of a flexible XBAR resonator in an embodiment in cross section and in top view;
figure 10 is a schematic diagram of a cascade of flexible XBAR filters.
In the drawings: 1-a first substrate; 2-a piezoelectric layer; 3-insulating protective layer; 4-a second substrate; 5-a temporary bonding layer; 6-a flexible substrate; 7-a top electrode; 8-flexible protective layer.
Detailed Description
The invention will be described in detail with reference to the drawings and specific embodiments, which are illustrative of the invention and are not to be construed as limiting the invention.
It should be noted that all the directional indications (such as up, down, left, right, front, back, upper end, lower end, top, bottom … …) in the embodiments of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indication is changed accordingly.
In the present invention, unless expressly stated or limited otherwise, the term "coupled" is to be interpreted broadly, e.g., "coupled" may be fixedly coupled, detachably coupled, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In addition, the descriptions related to "first", "second", etc. in the present invention are only for descriptive purposes and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature; in addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
Referring to fig. 1 to 9, a method for manufacturing a flexible shear wave thin film bulk acoustic wave filter includes the following steps:
step (1), taking a first substrate 1 as a preparation substrate of a piezoelectric film, depositing a piezoelectric layer 2 on the upper end surface of the first substrate 1, then growing an entire insulating protective layer 3 on the piezoelectric layer 2, and carrying out patterned etching on the insulating protective layer 3 to obtain a first composite substrate for later use;
step (2), taking the second substrate 4 as a bonding substrate, preparing a temporary bonding layer 5 on the upper end face of the second substrate 4, and then bonding a layer of flexible substrate 6 on the temporary bonding layer 5 to obtain a second composite substrate;
bonding the second composite substrate and the first composite substrate, peeling off the first substrate 1 after bonding is finished to expose the piezoelectric layer 2, preparing a top electrode 7 on the piezoelectric layer 2, and carrying out graphical processing on the top electrode 7;
step (4), covering the top electrode 7 on the piezoelectric layer 2 to prepare a flexible protection layer 8, simultaneously carrying out patterned photoetching on the flexible protection layer 8, and etching the flexible protection layer 8 above the middle part of the piezoelectric layer 2 and above the top electrode 7 to expose the top electrode 7 and form an upper cavity; debonding the second substrate 4 from the flexible substrate 6 to realize peeling, and obtaining a flexible filter device;
and (5) cascading a plurality of flexible filter devices to obtain the filter with the function of filtering different frequency bands.
Specifically, in the scheme of this embodiment, in the step (1) and the step (2), the first substrate 1 and the second substrate 4 are made of a silicon substrate, a sapphire substrate, a silicon carbide substrate, a gallium nitride substrate, an aluminum nitride substrate, or AlxGa1-xN buffer layer substrate, glass, plastic, gallium arsenide, steel, paper, silk, plastic, polyimide, parylene, polycarbonate, polyester resin, polyethylene naphthalate, polyethersulfone, polyetherimide, polydimethylsiloxane, polyvinyl alcohol or fluoropolymer.
Specifically, in this embodiment, in the step (1), the piezoelectric layer 2 is a single crystal piezoelectric film grown by epitaxy, a polycrystalline piezoelectric film grown by sputtering and having a high C-axis orientation, or AlN, ZnO, PZT, L innbo3L iTaO 3.
Specifically, in this embodiment, in the step (3), the top electrode 7 is one or a combination of two of graphene, gold, tungsten, molybdenum, platinum, ruthenium, iridium, germanium, copper, titanium tungsten, aluminum, chromium, and arsenic alloy, and the thickness of the top electrode 7 is 1 to 500 nm.
Specifically, in the embodiment of the present invention, in the step (1), the insulating protection layer 3 is made of one of SiO2, AlN, SiN, Si, plastic, polyimide, parylene, polycarbonate, polyester resin, polyethylene naphthalate, polyethersulfone, polyetherimide, polydimethylsiloxane, polyvinyl alcohol, or fluoropolymer.
Specifically, in this embodiment, in the step (4), the material of the flexible protection layer 8 is one of polyimide, parylene, polycarbonate, polyester resin, polyethylene naphthalate, polyethersulfone, polyetherimide, polydimethylsiloxane, polyvinyl alcohol, or fluoropolymer.
Specifically, in this embodiment, in the step (3), the top electrode 7 is rectangular, or interdigital, or spirally overlapped.
Specifically, in the scheme of this embodiment, the XBAR filter with any frequency capable of covering the whole communication frequency band is prepared by changing the number of flexible filter devices and the cascade connection mode.
Specifically, in this embodiment, in the step (1), the first substrate 1 is prepared by an epitaxial growth or lift-off method to prepare the piezoelectric layer 2.
Specifically, in the embodiment, in the step (3), the top electrode 7 is prepared on the piezoelectric layer 2 through an electron beam evaporation and lift-off process or a magnetron sputtering and patterning etching process.
Example 1:
(1) as shown in fig. 2, a first substrate 1 is taken as an epitaxial growth substrate, a 1 micron piezoelectric layer 2 (lithium niobate piezoelectric film) is prepared on the first substrate 1 by an epitaxial growth or peeling method, then an insulating protective layer 3 (photosensitive Polyimide (PI)) is spin-coated to a thickness of 6 microns, and then photoetching patterning is performed to obtain a first composite substrate, as shown in fig. 3;
(2) as shown in fig. 4, another second substrate 4 is taken, a temporary bonding layer 5 (temporary bonding glue PMMA) is spin-coated on the second substrate 4, and then PI with a certain thickness is prepared on the temporary bonding layer 5 by a spin coating method or a direct bonding method to be used as a flexible substrate 6, so as to obtain a second composite substrate;
(3) as shown in fig. 5, bonding the first composite substrate with the second composite substrate, and then peeling off the first substrate 1, as shown in fig. 6; then preparing a top electrode 7 by an electron beam evaporation and lift-off process or a magnetron sputtering and patterning etching process, as shown in FIG. 7;
(4) as shown in fig. 8, a flexible protective layer 8 (photosensitive PI) with a certain thickness is spin-coated on the top layer of the whole structure, and then patterned photolithography is performed on the flexible protective layer to expose the upper electrodes of the resonators; the entire structure is then debonded and the flexible device is peeled off the rigid substrate silicon, resulting in the device shown in fig. 9.
(5) Fig. 10 is a circuit diagram showing a circuit cascade of the fifth-order shear wave filter of the present embodiment.
The invention can omit a sacrificial layer and a CMP polishing process, has simple processing process, and greatly reduces the processing difficulty and the production cost of the flexible XBAR filter and improves the preparation yield of the flexible device because the adopted organic polymer insulating material has the advantages of simple preparation method, low material cost and easy operation in the wafer processing process.
The technical solutions provided by the embodiments of the present invention are described in detail above, and the principles and embodiments of the present invention are explained herein by using specific examples, and the descriptions of the embodiments are only used to help understanding the principles of the embodiments of the present invention; meanwhile, for a person skilled in the art, according to the embodiments of the present invention, there may be variations in the specific implementation manners and application ranges, and in summary, the content of the present description should not be construed as a limitation to the present invention.
Claims (10)
1. A method for preparing a flexible shear wave film bulk acoustic wave filter is characterized by comprising the following steps:
step (1), taking a first substrate as a preparation substrate of a piezoelectric film, depositing a piezoelectric layer on the upper end surface of the first substrate, then growing an entire insulating protective layer on the piezoelectric layer, and carrying out patterned etching on the insulating protective layer to obtain a first composite substrate for later use;
taking the second substrate as a bonding substrate, preparing a temporary bonding layer on the upper end face of the second substrate, and bonding a layer of flexible substrate on the temporary bonding layer to obtain a second composite substrate;
bonding the second composite substrate with the first composite substrate, peeling off the first substrate after bonding is finished to expose the piezoelectric layer, preparing a top electrode on the piezoelectric layer, and carrying out graphical processing on the top electrode;
step (4), covering a top electrode on the piezoelectric layer to prepare a flexible protection layer, simultaneously carrying out patterned photoetching on the flexible protection layer, and etching the flexible protection layer above the middle part of the piezoelectric layer and the top electrode to expose the top electrode to form an upper cavity; debonding the second substrate from the flexible substrate to realize stripping, and obtaining a flexible filter device;
and (5) cascading a plurality of flexible filter devices to obtain the filter with the function of filtering different frequency bands.
2. The method of manufacturing a flexible shear wave thin film bulk acoustic wave filter according to claim 1, wherein: in the step (1) and the step (2), the first substrate and the second substrate are made of silicon substrate, sapphire substrate, silicon carbide substrate, gallium nitride substrate, aluminum nitride substrate, and AlxGa1-xN buffer layer substrate, glass, plastic, arsenicGallium, steel, paper, silk, plastic, polyimide, parylene, polycarbonate, polyester resin, polyethylene naphthalate, polyethersulfone, polyetherimide, polydimethylsiloxane, polyvinyl alcohol or fluoropolymer, or a combination of more than one of the above.
3. The method according to claim 1, wherein in the step (1), the piezoelectric layer is a single crystal piezoelectric film grown by epitaxy, a polycrystalline piezoelectric film grown by sputtering and having a high C-axis orientation, or AlN, ZnO, PZT, L iNbO3L iTaO 3.
4. The method of manufacturing a flexible shear wave thin film bulk acoustic wave filter according to claim 1, wherein: in the step (3), the top electrode is one or two of graphene, gold, tungsten, molybdenum, platinum, ruthenium, iridium, germanium, copper, titanium tungsten, aluminum, chromium or arsenic alloy, and the thickness of the top electrode is 1-500 nm.
5. The method of manufacturing a flexible shear wave thin film bulk acoustic wave filter according to claim 1, wherein: in the step (1), the insulating protective layer is made of one of SiO2, AlN, SiN, Si, plastic, polyimide, parylene, polycarbonate, polyester resin, polyethylene naphthalate, polyethersulfone, polyetherimide, polydimethylsiloxane, polyvinyl alcohol, or fluoropolymer.
6. The method of manufacturing a flexible shear wave thin film bulk acoustic wave filter according to claim 1, wherein: in the step (4), the flexible protective layer is made of one of polyimide, parylene, polycarbonate, polyester resin, polyethylene naphthalate, polyethersulfone, polyetherimide, polydimethylsiloxane, polyvinyl alcohol or fluoropolymer.
7. The method of manufacturing a flexible shear wave thin film bulk acoustic wave filter according to claim 1, wherein: in the step (3), the top electrode is in a rectangular shape, an interdigital electrode shape or a spiral overlapping shape.
8. The method of manufacturing a flexible shear wave thin film bulk acoustic wave filter according to claim 1, wherein: the filter with any frequency capable of covering the whole communication frequency band is prepared by changing the number of the flexible filter devices and the cascading mode.
9. The method of manufacturing a flexible shear wave thin film bulk acoustic wave filter according to claim 1, wherein: in the step (1), the first substrate is used for preparing the piezoelectric layer by an epitaxial growth or peeling method.
10. The method of manufacturing a flexible shear wave thin film bulk acoustic wave filter according to claim 1, wherein: in the step (3), the top electrode is prepared on the piezoelectric layer through an electron beam evaporation and lift-off process or a magnetron sputtering and patterning etching process.
Priority Applications (1)
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| CN202010276797.3A CN111431499A (en) | 2020-04-10 | 2020-04-10 | Preparation method of flexible shear wave film bulk acoustic wave filter |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113381724A (en) * | 2021-07-02 | 2021-09-10 | 中国科学院上海微系统与信息技术研究所 | Bulk acoustic wave resonator and method for manufacturing the same |
| CN118316408A (en) * | 2024-05-31 | 2024-07-09 | 深圳新声半导体有限公司 | Preparation method of resonant cavity of bulk acoustic wave filter |
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2020
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113381724A (en) * | 2021-07-02 | 2021-09-10 | 中国科学院上海微系统与信息技术研究所 | Bulk acoustic wave resonator and method for manufacturing the same |
| CN113381724B (en) * | 2021-07-02 | 2024-05-24 | 中国科学院上海微系统与信息技术研究所 | Bulk acoustic wave resonator and method for manufacturing the same |
| CN118316408A (en) * | 2024-05-31 | 2024-07-09 | 深圳新声半导体有限公司 | Preparation method of resonant cavity of bulk acoustic wave filter |
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