WO2020062385A1 - Flexible substrate film bulk acoustic resonator and forming method therefor - Google Patents

Flexible substrate film bulk acoustic resonator and forming method therefor Download PDF

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Publication number
WO2020062385A1
WO2020062385A1 PCT/CN2018/112092 CN2018112092W WO2020062385A1 WO 2020062385 A1 WO2020062385 A1 WO 2020062385A1 CN 2018112092 W CN2018112092 W CN 2018112092W WO 2020062385 A1 WO2020062385 A1 WO 2020062385A1
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layer
film bulk
electrode
bulk acoustic
resonator according
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PCT/CN2018/112092
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French (fr)
Chinese (zh)
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刘伯华
张孟伦
杨清瑞
庞慰
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天津大学
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    • 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
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02047—Treatment of substrates
    • 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
    • H03H9/02—Details
    • H03H9/05—Holders; Supports
    • H03H9/0504—Holders; Supports for bulk acoustic wave devices
    • 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
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/13—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials
    • H03H9/131—Driving means, e.g. electrodes, coils for networks consisting of piezoelectric or electrostrictive materials consisting of a multilayered structure
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
    • H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
    • 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

Definitions

  • the present invention relates to the field of semiconductor technology, and in particular, to a flexible base film bulk acoustic wave resonator and a method of forming the same.
  • Piezoelectric bulk acoustic wave (Bulk Acoustic Wave, BAW for short) resonators have a wide range of applications due to their many unique characteristics such as miniaturization and integration.
  • BAW Bend Acoustic Wave
  • the piezoelectric film is used to make longitudinal resonance in the thickness direction.
  • the thin-film piezoelectric bulk acoustic resonator has been maturely applied to circuits such as filters, duplexers, and oscillators, and has become a feasible solution to replace surface acoustic wave devices and quartz crystal resonators.
  • thin-film bulk acoustic resonators The thin film bulk wave sensor with a mass adsorption sensitive effect and a thin film bulk acoustic wave resonator as a sensitive element can be used in the fields of biology, chemistry, medical diagnosis, environmental detection and the like.
  • These devices can be applied to smart bracelets / smart watches for tracking daily health and fitness, and can be attached to the skin surface for pulse, heart rate detection, blood pressure detection, local temperature detection, ECG detection, and blood oxygen saturation detection; It can also be attached to the surface of an aircraft wing as an embedded sensor to detect aircraft vibration under certain extreme conditions; it can also be integrated into clothing and used to make smart clothing that detects athletes' characteristic signals of movement. It is foreseeable that flexible electronic devices or systems will be widely used in the Internet of Things and wearable electronic devices.
  • the thin film piezoelectric bulk acoustic wave resonator (Film, Bulk, Acoustic, Resonator, FABR for short) is characterized in that the main body of the resonator has a sandwich structure, and the first electrode, the piezoelectric layer, and the second electrode are in order from bottom to top.
  • the area where the first electrode, the piezoelectric layer, and the second electrode overlap in the thickness direction is generally defined as the effective area of the resonator.
  • the first electrode and the second electrode are excitation electrodes, and their function is to cause mechanical vibration of each layer of the resonator.
  • the Q value is an important parameter of the resonator.
  • the Q value is the ratio of the total energy stored in the system to the energy lost by the resonator through various channels during the week.
  • the calculation formula is as follows:
  • ⁇ is the angular frequency
  • Etot is the total energy stored in the system
  • ⁇ E is the energy lost by the resonator through various paths during the week. It can be known from the formula (1) that the smaller the energy loss of the resonator, the higher the Q value, and the better the performance of the resonator.
  • the main energy loss paths can be divided into three categories: electrical loss, acoustic loss, and acoustic leakage.
  • the electrical loss is mainly caused by the resistance of the electrodes, wires, and test plates in the resonator structure;
  • the acoustic loss is caused by the mechanical damping of some mechanical energy into thermal energy when the sound wave propagates in the medium;
  • sound wave leakage refers to some sound waves It cannot be confined within the resonator, causing energy leakage.
  • Some acoustic waves include longitudinal acoustic waves, transverse acoustic waves, and surface acoustic waves.
  • the air cavity needs to be processed by a similar process such as inverted mold on a flexible substrate, and during the device transfer process, the device must be accurately positioned above the cavity by an alignment method under a microscope, so that Its manufacturing process is relatively complicated.
  • the present invention provides a flexible base film bulk acoustic wave resonator and a method for forming the same, which help to improve the Q value of the device, improve the performance of the device, and reduce the cost of device processing.
  • a flexible substrate thin film bulk acoustic resonator includes a flexible substrate, a bottom acoustic reflection layer, and a resonance structure, wherein: the bottom acoustic reflection layer is located on the flexible substrate; and the resonance structure is located on On the bottom acoustic reflection layer.
  • the bottom acoustic reflection layer includes: a single layer of low acoustic impedance layer; or N groups of Bragg reflection structures, where N is a positive integer, and each group of the Bragg reflection structures includes a low acoustic impedance layer and a high acoustic impedance layer .
  • the low acoustic impedance layer includes: epoxy-based resin, polyethylene oxide, silicon oxide, aluminum, carbon-doped silicon oxide, nanoporous methyl silsesquioxane, and nanoporous hydrogen silsesquioxane.
  • epoxy-based resin polyethylene oxide, silicon oxide, aluminum, carbon-doped silicon oxide, nanoporous methyl silsesquioxane, and nanoporous hydrogen silsesquioxane.
  • Alkanes, nanoporous mixtures containing methylsilsesquioxane and hydrosilsesquioxane, nanoglass, aerogel, xerogel, spin-on glass, parylene or SiLK Alkanes, nanoporous mixtures containing methylsilsesquioxane and hydrosilsesquioxane, nanoglass, aerogel, xerogel, spin-on glass, parylene or SiLK.
  • the thickness of the low acoustic impedance layer is less than 1 ⁇ m.
  • the high acoustic impedance layer includes: butyl synthetic rubber, polyethylene, neoprene, tungsten, molybdenum, platinum, ruthenium, iridium, tungsten-titanium, tantalum pentoxide, halo oxide, alumina, and silicide. , Niobium carbide, tantalum nitride, titanium carbide, titanium oxide, vanadium carbide, tungsten nitride, tungsten oxide, zirconium carbide, diamond-like or silicon-doped diamond.
  • the thickness of the high acoustic impedance layer is less than 1 ⁇ m.
  • the resonance structure includes a first electrode, a first piezoelectric layer, and a second electrode, which are sequentially arranged from bottom to top; or a first electrode, a first piezoelectric layer, a second electrode, and a second electrode.
  • the first piezoelectric layer and / or the second piezoelectric layer are composite piezoelectric layers.
  • the top surface of the flexible substrate has a micro cavity structure.
  • the width of the micro cavity is: 30 ⁇ m to 500 ⁇ m.
  • the depth of the micro cavity is: 0.1 ⁇ m to 10 ⁇ m.
  • the micro cavity structure is a triangular pyramid cavity array structure, a conical cavity array structure, or a triangular prism cavity array structure.
  • Another aspect of the present invention provides a method for forming a flexible base film bulk acoustic wave resonator, including: providing a sacrificial layer; forming a bottom acoustic reflection layer on the sacrificial layer; and forming a resonance structure on the bottom acoustic reflection layer. Removing the sacrificial layer to obtain a stacked structure, and then transferring the stacked structure to a flexible substrate, the stacked structure including the bottom acoustic reflection layer and the resonance structure.
  • the bottom acoustic reflection layer includes: a single layer of low acoustic impedance layer; or, N groups of Bragg reflection structures, where N is a positive integer, and each group of the Bragg reflection structures includes a low acoustic impedance layer and a high acoustic impedance layer .
  • the low acoustic impedance layer includes: epoxy-based resin, polyethylene oxide, silicon oxide, aluminum, carbon-doped silicon oxide, nanoporous methyl silsesquioxane, and nanoporous hydrogen silsesquioxane.
  • epoxy-based resin polyethylene oxide, silicon oxide, aluminum, carbon-doped silicon oxide, nanoporous methyl silsesquioxane, and nanoporous hydrogen silsesquioxane.
  • Alkanes, nanoporous mixtures containing methylsilsesquioxane and hydrosilsesquioxane, nanoglass, aerogel, xerogel, spin-on glass, parylene or SiLK Alkanes, nanoporous mixtures containing methylsilsesquioxane and hydrosilsesquioxane, nanoglass, aerogel, xerogel, spin-on glass, parylene or SiLK.
  • the thickness of the low acoustic impedance layer is less than 1 ⁇ m.
  • the high acoustic impedance layer includes: butyl synthetic rubber, polyethylene, neoprene, tungsten, molybdenum, platinum, ruthenium, iridium, tungsten-titanium, tantalum pentoxide, halo oxide, alumina, and silicide. , Niobium carbide, tantalum nitride, titanium carbide, titanium oxide, vanadium carbide, tungsten nitride, tungsten oxide, zirconium carbide, diamond-like or silicon-doped diamond.
  • the thickness of the high acoustic impedance layer is less than 1 ⁇ m.
  • the resonance structure includes a first electrode, a first piezoelectric layer, and a second electrode, which are sequentially arranged from bottom to top; or a first electrode, a first piezoelectric layer, a second electrode, and a second electrode.
  • the first piezoelectric layer and / or the second piezoelectric layer are composite piezoelectric layers.
  • it further comprises: forming a micro cavity structure on a top surface of the flexible substrate.
  • the width of the micro cavity is: 30 ⁇ m to 500 ⁇ m.
  • the depth of the micro cavity is: 0.1 ⁇ m to 10 ⁇ m.
  • the micro cavity structure is a triangular pyramid cavity array structure, a conical cavity array structure, or a triangular prism cavity array structure.
  • a bottom acoustic reflection layer is provided below the resonance structure, which can reflect the sound waves propagating to the bottom back to the resonance structure, reducing Energy loss, which increases device Q and improves device performance.
  • the cavity does not need to be processed on the substrate, so the complicated process steps of cavity fabrication are omitted, and because there is no cavity on the substrate, There is no need to align during the process, which can greatly improve the efficiency of device transfer, and because there is no cavity on the substrate, the contact area between the device and the substrate is larger, which makes the connection between the device and the substrate more secure without collapse.
  • FIG. 1 is a schematic diagram of a thin-film bulk acoustic wave resonator collapsed due to excessive bending;
  • FIG. 2 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a first embodiment of the present invention
  • FIG. 3 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a second embodiment of the present invention.
  • FIG. 4 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a third embodiment of the present invention.
  • FIG. 5A is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a fourth embodiment of the present invention.
  • 5B to 5G are detailed schematic diagrams of the micro cavity structure on the top surface of the flexible substrate in the flexible substrate thin film bulk acoustic resonator shown in FIG. 5A;
  • FIG. 6 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a fifth embodiment of the present invention.
  • FIG. 7 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a sixth embodiment of the present invention.
  • FIG. 8 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a seventh embodiment of the present invention.
  • first and second are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as “first” and “second” may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality” is two or more, unless specifically defined otherwise.
  • the terms “installation”, “connected”, “connected”, “fixed” and other terms shall be understood in a broad sense unless otherwise specified and defined, for example, they may be fixed connections or removable connections , Or integrally connected; it can be mechanical or electrical; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements.
  • the specific meanings of the above terms in the present invention can be understood according to specific situations.
  • the "first" or “down” of the second feature may include the first and second features in direct contact, and may also include the first and second features. Not directly, but through another characteristic contact between them.
  • the first feature is “above”, “above”, and “above” the second feature, including that the first feature is directly above and obliquely above the second feature, or merely indicates that the first feature is higher in level than the second feature.
  • the first feature is “below”, “below”, and “below” of the second feature, including the fact that the first feature is directly below and obliquely below the second feature, or merely indicates that the first feature is less horizontal than the second feature.
  • a first aspect of the present invention provides a flexible base film bulk acoustic wave resonator.
  • the flexible substrate thin film bulk acoustic resonator according to the embodiment of the present invention includes a flexible substrate, a bottom acoustic reflection layer, and a resonance structure, wherein: the bottom acoustic reflection layer is located on the flexible substrate; and the resonance structure is located on the bottom acoustic reflection layer.
  • a bottom acoustic reflection layer is provided below the resonance structure, which can reflect sound waves propagating to the bottom back to the resonance structure, reduce energy loss, thereby improving the Q value of the device and improving Device performance.
  • the flexible substrate may be polyimide (PI), polydimethylsiloxane (PDMS), polyester resin (PET) polycarbonate (PC), polyethylene naphthalate (PEN), polymer It consists of ether sulfone (PES), polyetherimide (PEI), polyvinyl alcohol (PVA), and various fluoropolymers (FEP).
  • PI polyimide
  • PDMS polydimethylsiloxane
  • PET polyester resin
  • PEN polyethylene naphthalate
  • PES ether sulfone
  • PEI polyetherimide
  • PVA polyvinyl alcohol
  • FEP fluoropolymers
  • the bottom acoustic reflection layer may include: a single layer of low acoustic impedance layer; or N groups of Bragg reflection structures, where N is a positive integer, and each group of Bragg reflection structures includes a low acoustic impedance layer and a high acoustic impedance layer.
  • the thickness of the low acoustic impedance layer and the high acoustic impedance layer are both one-quarter or three-quarter the wavelength of the acoustic wave.
  • the bottom acoustic reflection layer contains only a single low acoustic impedance layer, the device has the advantages of being thinner and more flexible.
  • the bottom acoustic reflection layer contains multiple sets of Bragg reflection structures, the sound wave reflection effect is better.
  • the bottom acoustic layer contains a single group of Bragg reflection structures, the device is moderately thin and flexible, and the acoustic reflection effect is also moderate.
  • the low acoustic impedance layer is composed of a low acoustic impedance material, which may be silicon oxide, aluminum, carbon-doped silicon oxide, nanoporous methylsilsesquioxane, nanoporous hydrogen silsesquioxane, containing formazan Nanoporous mixtures of methylsilsesquioxane (MSQ) and hydrogen silsesquioxane (HSQ), nanoglasses, aerogels, xerogels, spin-on glass, polymer Paraxylene, SiLK (SiLK is a low dielectric constant material developed by Dow Chemical Company and is currently widely used in integrated circuit production.
  • SiLK is a low dielectric constant material developed by Dow Chemical Company and is currently widely used in integrated circuit production.
  • the thickness of the low acoustic impedance layer is less than 1 ⁇ m. Since it is a thin film, it can increase the flexibility of the device.
  • the high acoustic impedance layer is composed of a high acoustic resistance material, which can be tungsten, molybdenum, platinum, ruthenium, iridium, tungsten titanium, tantalum pentoxide, halo oxide, alumina, silicide, niobium carbide, tantalum nitride, titanium carbide, Titanium oxide, vanadium carbide, tungsten nitride, tungsten oxide, zirconium carbide, diamond-like or silicon-doped diamond.
  • the bottom acoustic reflection layer is all made of a flexible material, which can effectively improve the flexibility and bendability of the device and enable it to adapt to more complicated environments.
  • the low acoustic impedance layer may include an epoxy-based resin or polyethylene.
  • the high acoustic impedance layer includes butyl synthetic rubber, polyethylene, or neoprene. It should be noted that the low acoustic impedance layer and the high acoustic impedance layer may be either pure polymer flexible materials of the above-mentioned specific materials, or composite flexible materials including these specific materials.
  • the thickness of the high acoustic impedance layer is less than 1 ⁇ m. Since it is a thin film, the flexibility of the device can be increased.
  • the resonance structure may be the simplest sandwich structure, including a first electrode, a first piezoelectric layer, and a second electrode arranged in order from bottom to top.
  • the resonance structure may also be a "3 + 2" sandwich structure, which includes a first electrode, a first piezoelectric layer, a second electrode, a second piezoelectric layer, and a third electrode arranged in order from bottom to top.
  • the resonance structure may also be a sandwich structure stacked in two vertical directions, including a first electrode, a first piezoelectric layer, a second electrode, a decoupling layer, a third electrode, a second piezoelectric layer, Fourth electrode.
  • the electrode material may be metals such as gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), aluminum (Al), and titanium (Ti). And their alloys.
  • the material of the piezoelectric layer can be aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO 3 ), quartz (Quartz), potassium niobate (KNbO 3 ), or tantalic acid. Materials such as lithium (LiTaO 3 ) and combinations thereof.
  • the piezoelectric layer may be a conventional single material layer or a composite piezoelectric layer.
  • the first piezoelectric layer and / or the second piezoelectric layer are composite piezoelectric layers.
  • the composite piezoelectric layer is alternately arranged by two piezoelectric materials to achieve the purpose of being relatively thick.
  • the two piezoelectric materials may be AlN / AlGaN or other piezoelectric materials.
  • a composite piezoelectric layer can avoid stress caused by lattice defects such as dislocations and slippage when growing thicker piezoelectric materials.
  • the top surface of the flexible substrate has a micro cavity structure.
  • the substrate's ability to reflect sound waves from the resonator can be effectively increased, and the thickness of the bottom acoustic reflection layer can be reduced, which can effectively improve the flexibility and bendability of the device. It can adapt to more complicated environment, meanwhile, these tiny cavity structures can also increase the firmness of the connection between the device and the substrate, and can effectively prevent the device from falling off.
  • the micro cavity structure may be a triangular pyramid cavity array structure, a conical cavity array structure, or a triangular prism cavity array structure.
  • the width of the micro-cavity should be controlled within a suitable range.
  • the resonator will completely fall into the cavity and contact the substrate.
  • the depth of the micro-cavity should also be controlled within a suitable range. Shallow devices easily come into contact with the bottom during the bending process.
  • the width of the micro-cavities can be: 30 ⁇ m to 500 ⁇ m, typically 100 ⁇ m; the depth of the micro-cavities can be: 0.1 ⁇ m to 10 ⁇ m, typically 1 ⁇ m.
  • a second aspect of the present invention provides a method for forming a flexible base film bulk acoustic wave resonator.
  • a method for forming a flexible base film bulk acoustic wave resonator includes: providing a sacrificial layer; forming a bottom acoustic reflection layer on the sacrificial layer; forming a resonance structure on the bottom acoustic reflection layer; removing the sacrificial layer, thereby A stacked structure is obtained, and then the stacked structure is transferred to a flexible substrate.
  • the stacked structure includes a bottom acoustic reflection layer and a resonance structure.
  • a bottom acoustic reflection layer is provided below the resonance structure, and a sound wave propagating toward the bottom can be reflected back to the resonance structure, thereby reducing energy loss, thereby Improved device Q value and improved device performance.
  • the cavity does not need to be processed on the substrate, so the complicated process steps of cavity fabrication are omitted, and because there is no cavity on the substrate, There is no need to align during the process, which can greatly improve the efficiency of device transfer, and because there is no cavity on the substrate, the contact area between the device and the substrate is larger, which makes the connection between the device and the substrate more secure without collapse.
  • the bottom acoustic reflection layer may include: a single layer of low acoustic impedance layer; or N-layer Bragg reflection structures, where N is a positive integer, and each group of Bragg reflection structures includes a low acoustic impedance layer and a high acoustic impedance layer.
  • the thickness of the low acoustic impedance layer and the high acoustic impedance layer are both one-quarter or three-quarter the wavelength of the acoustic wave.
  • the bottom acoustic reflection layer contains only a single low acoustic impedance layer, the device has the advantages of being thinner and more flexible.
  • the bottom acoustic reflection layer contains multiple sets of Bragg reflection structures, the sound wave reflection effect is better.
  • the bottom acoustic reflection layer contains a single group of Bragg reflection structures, the characteristics of the device are moderately thin and flexible, and the acoustic reflection effect is also moderate.
  • the low acoustic impedance layer is composed of a low acoustic impedance material, which can usually be silicon oxide, aluminum, carbon-doped silicon oxide, nanoporous methyl silsesquioxane, nano porous hydrogen silsesquioxane, and methyl silsesquioxane.
  • a low acoustic impedance material which can usually be silicon oxide, aluminum, carbon-doped silicon oxide, nanoporous methyl silsesquioxane, nano porous hydrogen silsesquioxane, and methyl silsesquioxane.
  • Nanoporous mixtures of methylsilsesquioxane (MSQ) and hydrogen silsesquioxane (HSQ) nanoglasses, aerogels, xerogels, spin-on glass, polyisocyanate Toluene
  • SiLK SiLK is a low dielectric constant material developed by Dow Chemical Company and is currently widely used in integrated circuit production.
  • the thickness of the low acoustic impedance layer is less than 1 ⁇ m. Since it is a thin film, it can increase the flexibility of the device.
  • the high acoustic impedance layer is composed of a high acoustic resistance material, which can usually be tungsten, molybdenum, platinum, ruthenium, iridium, tungsten titanium, tantalum pentoxide, halo oxide, alumina, silicide, niobium carbide, tantalum nitride, Titanium carbide, titanium oxide, vanadium carbide, tungsten nitride, tungsten oxide, zirconium carbide, diamond-like or silicon-doped diamond.
  • the thickness of the high acoustic impedance layer is less than 1 ⁇ m. Since it is a thin film, the flexibility of the device can be increased.
  • the bottom acoustic reflection layer is all made of a polymer flexible material, which can effectively improve the flexibility and bendability of the device and enable it to adapt to more complicated environments.
  • the low acoustic impedance layer may include an epoxy-based resin or polyethylene.
  • the high acoustic impedance layer includes butyl synthetic rubber, polyethylene, or neoprene. It should be noted that the low acoustic impedance layer and the high acoustic impedance layer may be either pure polymer flexible materials of the above-mentioned specific materials, or composite flexible materials including these specific materials.
  • the resonance structure may be the simplest sandwich structure, including a first electrode, a first piezoelectric layer, and a second electrode arranged in order from bottom to top.
  • the resonance structure may also be a "3 + 2" sandwich structure, which includes a first electrode, a first piezoelectric layer, a second electrode, a second piezoelectric layer, and a third electrode arranged in order from bottom to top.
  • the resonance structure may also be a sandwich structure stacked in two vertical directions, including a first electrode, a first piezoelectric layer, a second electrode, a decoupling layer, a third electrode, a second piezoelectric layer, Fourth electrode.
  • the electrode material may be metals such as gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), aluminum (Al), and titanium (Ti). And their alloys.
  • the material of the piezoelectric layer can be aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO 3 ), quartz (Quartz), potassium niobate (KNbO 3 ), or tantalic acid. Materials such as lithium (LiTaO 3 ) and combinations thereof.
  • the piezoelectric layer may be a conventional single material layer or a composite piezoelectric layer.
  • the first piezoelectric layer and / or the second piezoelectric layer are composite piezoelectric layers.
  • the composite piezoelectric layer is alternately arranged by two piezoelectric materials to achieve the purpose of being relatively thick.
  • the two piezoelectric materials may be AlN / AlGaN or other piezoelectric materials.
  • a composite piezoelectric layer can avoid stress caused by lattice defects such as dislocations and slippage when growing thicker piezoelectric materials.
  • the top surface of the flexible substrate has a micro cavity structure.
  • the substrate's ability to reflect sound waves from the resonator can be effectively increased, and the thickness of the bottom acoustic reflection layer can be reduced, which can effectively improve the flexibility and bendability of the device. It can adapt to more complicated environment, meanwhile, these tiny cavity structures can also increase the firmness of the connection between the device and the substrate, and can effectively prevent the device from falling off.
  • the micro cavity structure may be a triangular pyramid cavity array structure, a conical cavity array structure, or a triangular prism cavity array structure.
  • the width of the micro-cavity should be controlled within a suitable range.
  • the resonator will completely fall into the cavity and contact the substrate.
  • the depth of the micro-cavity should also be controlled within a suitable range. Shallow devices easily come into contact with the bottom during the bending process.
  • the width of the micro-cavities can be: 30 ⁇ m to 500 ⁇ m, typically 100 ⁇ m; the depth of the micro-cavities can be: 0.1 ⁇ m to 10 ⁇ m, typically 1 ⁇ m.
  • FIG. 2 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a first embodiment of the present invention.
  • the manufacturing process of the flexible thin film bulk acoustic wave resonator (FBAR) 200 includes: firstly etching a silicon substrate to form a cavity and depositing a layer of sacrificial material, and smoothing and smoothing its surface through chemical mechanical planarization, Forming a sacrificial layer; depositing a bottom acoustic reflection layer including two sets of Bragg reflecting structures, including high acoustic impedance layers 213 and 209 and low acoustic impedance layers 211 and 207; depositing a first electrode 205; depositing a piezoelectric layer 203; depositing a second electrode 201; then the sacrificial layer is removed; then, by a transfer method, under a micro operation, the FBAR with a Bragg reflection structure prepared on a silicon substrate is lifted and placed on
  • the vertical region of the first electrode 205, the piezoelectric layer 203, and the second electrode 201 is the effective region of the resonator.
  • an alternating voltage signal of a certain frequency is applied between the first electrode 205 and the second electrode 201, due to the inverse piezoelectric effect of the piezoelectric material, a sound wave propagating vertically is generated between the upper and lower electrodes in the effective area. The sound wave will be reflected back and forth between the interface between the second electrode 201 and the air and the Bragg reflection structure under the first electrode 205 and resonate at a certain frequency.
  • the thin-film bulk acoustic wave resonator when the thin-film bulk acoustic wave resonator is transferred to a flexible substrate, since the cavity does not need to be processed on the substrate, the complicated process steps of making the cavity are omitted, and since there is no cavity on the substrate, the transfer There is no need to align during the process, which can greatly improve the efficiency of device transfer, and because there is no cavity on the substrate, the contact area between the device and the substrate is larger, which makes the connection between the device and the substrate more secure without collapse.
  • the manufacturing process of the flexible thin film bulk acoustic resonator (FBAR) 300 includes: depositing a sacrificial layer; depositing a bottom acoustic reflective layer including a single set of Bragg reflective structures, including a high acoustic impedance layer 309 and a low acoustic Resistive layer 307; deposition of first electrode 305; deposition of piezoelectric layer 303; deposition of second electrode 301; removal of sacrificial layer; and then, using a transfer method and under a microscopic operation, a Bragg with silicon substrate is prepared.
  • the FBAR of the reflective structure is lifted and placed on the flexible substrate 311 to form a flexible thin film bulk acoustic resonator. This reduces the number of Bragg reflective structures, increases the flexibility and bending performance of the device, and enables it to adapt to more complex environments.
  • FIG. 4 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a third embodiment of the present invention.
  • the manufacturing process of the flexible thin film bulk acoustic resonator (FBAR) 400 includes: depositing a sacrificial layer; depositing a bottom acoustic reflection layer including only a low acoustic impedance layer 407; depositing a first electrode 405; Deposition the piezoelectric layer 403; deposit the second electrode 401; remove the sacrificial layer; and then, by a transfer method, under a micro operation, lift the FBAR prepared with a Bragg reflection structure on a silicon substrate and place it Onto a flexible substrate 409 to form a flexible thin film bulk acoustic resonator.
  • the Bragg reflection structure only includes a layer of low acoustic impedance layer 407, and the low acoustic impedance layer selects a material whose acoustic impedance is as close to zero as possible, so as to ensure the sound wave reflection ability, and further reduce the structure of the bottom acoustic reflection layer, The device's flexibility and bending performance are further increased, enabling it to adapt to more complex environments.
  • the manufacturing process of the flexible thin film bulk acoustic resonator (FBAR) 500 includes: depositing a sacrificial layer; depositing a bottom acoustic reflective layer including a single set of Bragg reflective structures, namely a high acoustic impedance layer 509 and a low acoustic Resistive layer 507; deposition of first electrode 505; deposition of piezoelectric layer 503; deposition of second electrode 501; removal of sacrificial layer; and then, by transfer method, under micro-operation, a Bragg with silicon substrate is prepared.
  • the FBAR of the reflective structure is lifted and placed on the flexible substrate 511 to form a flexible thin film bulk acoustic resonator.
  • the flexible substrate is produced by inverted mold or other similar process methods to have a series of microcavity structures on the surface, which can be multiple triangular pyramids (5E), cones (5F) or triangular prisms (5G) or other phases.
  • the cells of similar structure are arranged in an array, and the top surfaces of the formed substrates are respectively shown in FIG. 5B, 5C, or 5D.
  • the width of the micro-cavities can be: 30 ⁇ m to 500 ⁇ m, typically 100 ⁇ m; the depth of the micro-cavities can be: 0.1 ⁇ m to 10 ⁇ m, typically 1 ⁇ m.
  • a series of tiny cavity structures formed on the flexible substrate can effectively increase the substrate's ability to reflect the acoustic waves of the resonant structure, thereby reducing the number of Bragg reflective structures, and thus effectively improving the flexibility of the device.
  • the flexibility and flexibility make it able to adapt to more complex environments.
  • these tiny cavity structures can also increase the firmness of the connection between the device and the substrate, and can effectively prevent the device from falling off.
  • FIG. 6 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a fifth embodiment of the present invention.
  • the manufacturing process of the flexible stacked thin-film bulk acoustic wave resonator 600 includes: depositing a sacrificial layer; depositing a bottom acoustic reflection layer including a single group of Bragg reflective structures, that is, including a high acoustic impedance layer 613 and a low acoustic wave Resistance layer 611; deposition of first electrode 609; deposition of first piezoelectric layer 607; deposition of second electrode 605; deposition of second piezoelectric layer 603; deposition of third electrode 601; removal of the sacrificial layer; Under a microscopic operation, a stacked thin film bulk acoustic wave resonator with a Bragg reflection structure prepared on a silicon substrate is lifted and placed on a flexible substrate 615 to form a flexible stacked bulk acoustic
  • FIG. 7 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a sixth embodiment of the present invention.
  • the manufacturing process of the flexible coupling resonant filter 700 includes: depositing a sacrificial layer; depositing a bottom acoustic reflection layer including a single set of Bragg reflection structures, including a high acoustic impedance layer 718 and a low acoustic impedance layer 715; Deposit first bottom electrode 713; deposit first piezoelectric layer 711; deposit first top electrode 709; deposit decoupling layer 707; deposit second bottom electrode 705; deposit second piezoelectric layer 703; deposit second top electrode 701;
  • the sacrificial layer is removed; then, by a transfer method, under a micro operation, the coupled resonant filter with a Bragg reflection structure prepared on a silicon substrate is lifted and placed on a flexible substrate 721 to form a flexible stack Type bulk acoustic wave resonator.
  • the manufacturing process of a flexible thin film bulk acoustic wave resonator (FBAR) 800 includes: firstly processing a FBAR with a Bragg reflection structure on a single crystal silicon substrate, and the manufacturing sequence is: depositing a sacrificial layer ; Deposit a bottom acoustic reflection layer including a single set of Bragg reflective structures, including a high acoustic impedance layer 813 and a low acoustic impedance layer 811; deposit a first electrode 809; deposit a piezoelectric layer, and the piezoelectric layer is alternately grown from two piezoelectric materials to To achieve a thicker overall, for example, the two piezoelectric materials can be AlN / AlGaN or other piezoelectric materials, where the first piezoelectric material layer 807 is AlN and the second piezoelectric
  • the thickness of the grown AlGaN is thicker, the thickness of the single layer is about 1 to 10 ⁇ m, the thickness of the grown AlN layer is thinner, and the thickness of the single layer is about 10 to 30 nanometers.
  • the manufacturing method of this embodiment can obtain a flexible thin film bulk acoustic wave resonator with a thick piezoelectric layer, and at the same time, its connection firmness, bendability and flexibility are reliable.

Abstract

Provided are a flexible substrate film bulk acoustic resonator (200, 300, 400, 500, 700, 800) and a forming method therefor, which is helpful to increase the Q value of the device and improve the performance of the device, and can reduce the cost for processing and manufacturing the device. The flexible substrate film bulk acoustic resonator (200, 300, 400, 500, 700, 800) comprises: a flexible substrate (215, 311, 409, 511, 615, 721, 815), a bottom acoustic reflection layer, and a resonant structure, wherein the bottom acoustic reflection layer is located above the flexible substrate (215, 311, 409, 511, 615, 721, 815), and the resonant structure is located above the bottom acoustic reflection layer.

Description

一种柔性基底薄膜体声波谐振器以及形成方法Flexible base film bulk acoustic wave resonator and forming method 技术领域Technical field
本发明涉及半导体技术领域，特别地涉及一种柔性基底薄膜体声波谐振器以及形成方法。The present invention relates to the field of semiconductor technology, and in particular, to a flexible base film bulk acoustic wave resonator and a method of forming the same.
背景技术Background technique
压电体声波(Bulk Acoustic Wave，简称BAW)谐振器由于具有小型化和可集成化等许多独特的特性，使其具有广泛的应用范围。在通讯领域中，凭借其小体积、轻质量、宽频带、低插入损耗、陡滚降和高品质因子以及低功耗、低相位噪声等优势，利用压电薄膜在厚度方向的纵向谐振所制成的薄膜压电体声波谐振器已成熟应用于滤波器、双工器和振荡器等电路中，已经成为替代表面声波器件和石英晶体谐振器的一个可行性方案；另外，薄膜体声波谐振器具有质量吸附敏感效应，以薄膜体声波谐振器为敏感原件的薄膜体波传感器可用于生物、化学、医疗诊断、环境检测等领域中。Piezoelectric bulk acoustic wave (Bulk Acoustic Wave, BAW for short) resonators have a wide range of applications due to their many unique characteristics such as miniaturization and integration. In the communication field, with its small size, light weight, wide frequency band, low insertion loss, steep roll-off and high quality factor, as well as low power consumption and low phase noise, the piezoelectric film is used to make longitudinal resonance in the thickness direction. The thin-film piezoelectric bulk acoustic resonator has been maturely applied to circuits such as filters, duplexers, and oscillators, and has become a feasible solution to replace surface acoustic wave devices and quartz crystal resonators. In addition, thin-film bulk acoustic resonators The thin film bulk wave sensor with a mass adsorption sensitive effect and a thin film bulk acoustic wave resonator as a sensitive element can be used in the fields of biology, chemistry, medical diagnosis, environmental detection and the like.
与此同时，柔性传感设备正成为研究热潮，已相继出现柔性基底上温度、湿度传感器，基于聚酰亚胺(Polyimide，简称PI)基底以表面声波(surface acoustic wave，简称SAW)滤波器为原理的无源无线传感器以及基于聚酰亚胺PI的不定型硅温度传感器等。与传统传感设备相比，柔性传感器具有质量轻、体积小、可弯曲、可拉伸、可贴合到某些不规则物体表面的特点。这些器件可以应用到智能手环/智能手表中，用于追踪日常健康和健身，可以贴于皮肤表面用于脉搏、心率检测、血压检测、局部温度检测、心电检测、血氧饱和度检测；也可以作为嵌入式传感器贴到飞机机翼表面，用于检测飞机在某些极端条件下的震动；还可以集成到衣服中，用于制作检测运动员运动特征信号的智能衣物。可以预见的是，柔性电子器件或系统将被广泛应用到 物联网以及可穿戴电子设备中等。At the same time, flexible sensing equipment is becoming a research boom, and temperature and humidity sensors on flexible substrates have successively emerged. Based on polyimide (PI) substrates, surface acoustic wave (SAW) filters are used as Principles of passive wireless sensors and amorphous silicon temperature sensors based on polyimide PI. Compared with traditional sensing devices, flexible sensors have the characteristics of light weight, small size, bendable, stretchable, and conformable to the surface of some irregular objects. These devices can be applied to smart bracelets / smart watches for tracking daily health and fitness, and can be attached to the skin surface for pulse, heart rate detection, blood pressure detection, local temperature detection, ECG detection, and blood oxygen saturation detection; It can also be attached to the surface of an aircraft wing as an embedded sensor to detect aircraft vibration under certain extreme conditions; it can also be integrated into clothing and used to make smart clothing that detects athletes' characteristic signals of movement. It is foreseeable that flexible electronic devices or systems will be widely used in the Internet of Things and wearable electronic devices.
薄膜压电体声波谐振器(Film Bulk Acoustic Resonator，简称FABR)，其特征是谐振器主体部分具有三明治结构，从下至上依次为第一电极、压电层和第二电极。通常将第一电极、压电层、第二电极在厚度方向上重叠的区域定义为谐振器的有效区域。第一电极和第二电极为激励电极，它们的作用是引起谐振器各层的机械震荡。当在电极之间施加一定频率的交变电压信号时，由于压电材料所具有的逆压电效应，有效区域内的上下电极之间会产生垂直方向传播的声波，声波在第二电极与空气的交界面和第一电极下的声反射结构之间来回反射并在一定频率下产生谐振。The thin film piezoelectric bulk acoustic wave resonator (Film, Bulk, Acoustic, Resonator, FABR for short) is characterized in that the main body of the resonator has a sandwich structure, and the first electrode, the piezoelectric layer, and the second electrode are in order from bottom to top. The area where the first electrode, the piezoelectric layer, and the second electrode overlap in the thickness direction is generally defined as the effective area of the resonator. The first electrode and the second electrode are excitation electrodes, and their function is to cause mechanical vibration of each layer of the resonator. When an alternating voltage signal of a certain frequency is applied between the electrodes, due to the inverse piezoelectric effect of the piezoelectric material, a sound wave propagating vertically is generated between the upper and lower electrodes in the effective area, and the sound wave is transmitted between the second electrode and the air. The interface between the and the acoustic reflection structure under the first electrode reflects back and forth and generates resonance at a certain frequency.
Q值是谐振器一项重要参数，Q值为系统储存的总能量与每周期内谐振器通过各种途径损耗的能量的比值，其计算公式如下：The Q value is an important parameter of the resonator. The Q value is the ratio of the total energy stored in the system to the energy lost by the resonator through various channels during the week. The calculation formula is as follows:
Q＝ωEtot/ΔE     (1)Q = ωEtot / ΔE (1)
其中ω是角频率，Etot是系统储存的总能量，ΔE是每周期内谐振器通过各种途径损耗的能量。由公式(1)可知，谐振器的能量损耗越少，其Q值越高，谐振器的性能越好。对于薄膜体声波谐振器，其主要的能量损耗途径可以分为三类：电学损耗、声学损耗、声波泄露。其中，电学损耗主要由谐振器结构中的电极、导线、测试盘等电阻造成的；声学损耗是由声波在介质中传播时，材料阻尼导致部分机械能转化成热能而造成；声波泄露是指部分声波不能被局限于谐振器内，造成能量泄露，部分声波包括纵向声波、横向声波和声表面波泄露。Where ω is the angular frequency, Etot is the total energy stored in the system, and ΔE is the energy lost by the resonator through various paths during the week. It can be known from the formula (1) that the smaller the energy loss of the resonator, the higher the Q value, and the better the performance of the resonator. For thin-film bulk acoustic resonators, the main energy loss paths can be divided into three categories: electrical loss, acoustic loss, and acoustic leakage. Among them, the electrical loss is mainly caused by the resistance of the electrodes, wires, and test plates in the resonator structure; the acoustic loss is caused by the mechanical damping of some mechanical energy into thermal energy when the sound wave propagates in the medium; sound wave leakage refers to some sound waves It cannot be confined within the resonator, causing energy leakage. Some acoustic waves include longitudinal acoustic waves, transverse acoustic waves, and surface acoustic waves.
然而，对于在柔性基底上带有空气腔的薄膜体声波谐振器，其所面临的一个问题是：当器件处于高温环境时，由于器件谐振部分的第二电极101、压电层102、第一电极103与柔性基底105之间的热应力不匹配，导致器件的塌陷，从而与空腔接触；或者当器件处于过度弯曲时，也会导致器件的塌陷，从而与空腔接触。如图1所示，这样会使得声波通过接触部分泄露到基底之中，从而降低了声波在第一电极 103与空腔104之间的反射能力，导致谐振器的Q值降低、性能下降。同时器件在加工的过程中，需要在柔性基底上通过倒模等类似的工艺方法加工空气腔，而且在器件转移的过程需要在显微镜下通过对准的方法将器件准确安放在空腔上方，使其加工制作过程相对复杂。However, for a thin-film bulk acoustic wave resonator with an air cavity on a flexible substrate, one of the problems it faces is that when the device is in a high-temperature environment, the second electrode 101, piezoelectric layer 102, first The thermal stress mismatch between the electrode 103 and the flexible substrate 105 causes the device to collapse and contact the cavity; or when the device is over-bent, it also causes the device to collapse and contact the cavity. As shown in FIG. 1, this will cause the sound wave to leak into the substrate through the contact portion, thereby reducing the reflection ability of the sound wave between the first electrode 103 and the cavity 104, resulting in a decrease in the Q value and performance of the resonator. At the same time, during the processing of the device, the air cavity needs to be processed by a similar process such as inverted mold on a flexible substrate, and during the device transfer process, the device must be accurately positioned above the cavity by an alignment method under a microscope, so that Its manufacturing process is relatively complicated.
基于此，如何保证薄膜体声波谐振器在柔性基底上具有良好的性能，特别是具有高的Q值，同时能够简化器件加工的步骤，降低其加工成本，成为本领域技术人员亟待解决的一个技术难题。Based on this, how to ensure that the thin-film bulk acoustic wave resonator has good performance on a flexible substrate, in particular, has a high Q value, and at the same time can simplify the steps of device processing and reduce its processing costs, has become a technology urgently solved by those skilled in the art. problem.
发明内容Summary of the Invention
有鉴于此，本发明提供一种柔性基底薄膜体声波谐振器以及形成方法，有助于提高器件的Q值，改善器件性能，并能降低器件加工制作的成本。In view of this, the present invention provides a flexible base film bulk acoustic wave resonator and a method for forming the same, which help to improve the Q value of the device, improve the performance of the device, and reduce the cost of device processing.
本发明一方面提出一种柔性基底薄膜体声波谐振器，包括：柔性基底、底部声反射层、以及谐振结构，其中：所述底部声反射层位于所述柔性基底之上；所述谐振结构位于所述底部声反射层之上。According to an aspect of the present invention, a flexible substrate thin film bulk acoustic resonator includes a flexible substrate, a bottom acoustic reflection layer, and a resonance structure, wherein: the bottom acoustic reflection layer is located on the flexible substrate; and the resonance structure is located on On the bottom acoustic reflection layer.
可选地，所述底部声反射层包括：单层低声阻抗层；或者，N组布拉格反射结构，其中N为正整数，每组所述布拉格反射结构包括低声阻抗层和高声阻抗层。Optionally, the bottom acoustic reflection layer includes: a single layer of low acoustic impedance layer; or N groups of Bragg reflection structures, where N is a positive integer, and each group of the Bragg reflection structures includes a low acoustic impedance layer and a high acoustic impedance layer .
可选地，所述低声阻抗层包括：环氧基树脂、聚乙二烯、氧化硅、铝、碳掺杂氧化硅、纳米多孔甲基倍半硅氧烷、纳米多孔氢倍半硅氧烷、包含甲基倍半硅氧烷和氢硅倍半环氧乙烷的纳米多孔混合物、纳米玻璃、气凝胶、干凝胶、旋涂玻璃、聚对二甲苯或SiLK。Optionally, the low acoustic impedance layer includes: epoxy-based resin, polyethylene oxide, silicon oxide, aluminum, carbon-doped silicon oxide, nanoporous methyl silsesquioxane, and nanoporous hydrogen silsesquioxane. Alkanes, nanoporous mixtures containing methylsilsesquioxane and hydrosilsesquioxane, nanoglass, aerogel, xerogel, spin-on glass, parylene or SiLK.
可选地，所述低声阻抗层的厚度小于1μm。Optionally, the thickness of the low acoustic impedance layer is less than 1 μm.
可选地，所述高声阻抗层包括：丁基合成橡胶、聚乙烯、氯丁橡 胶、钨、钼、铂、钌、铱、钨钛、五氧化二钽、氧化哈、氧化铝、硅化络、碳化铌、氮化钽、碳化钛、氧化钛、碳化钒、氮化钨、氧化钨、碳化锆、类金刚石或硅掺杂的金刚石。Optionally, the high acoustic impedance layer includes: butyl synthetic rubber, polyethylene, neoprene, tungsten, molybdenum, platinum, ruthenium, iridium, tungsten-titanium, tantalum pentoxide, halo oxide, alumina, and silicide. , Niobium carbide, tantalum nitride, titanium carbide, titanium oxide, vanadium carbide, tungsten nitride, tungsten oxide, zirconium carbide, diamond-like or silicon-doped diamond.
可选地，所述高声阻抗层的厚度小于1μm。Optionally, the thickness of the high acoustic impedance layer is less than 1 μm.
可选地，所述谐振结构包括自下而上依次排列的：第一电极、第一压电层和第二电极；或者，第一电极、第一压电层、第二电极、第二压电层、第三电极；或者，第一电极、第一压电层、第二电极、解耦层、第三电极、第二压电层、第四电极。Optionally, the resonance structure includes a first electrode, a first piezoelectric layer, and a second electrode, which are sequentially arranged from bottom to top; or a first electrode, a first piezoelectric layer, a second electrode, and a second electrode. An electric layer, a third electrode; or a first electrode, a first piezoelectric layer, a second electrode, a decoupling layer, a third electrode, a second piezoelectric layer, and a fourth electrode.
可选地，所述第一压电层和/或所述第二压电层为复合压电层。Optionally, the first piezoelectric layer and / or the second piezoelectric layer are composite piezoelectric layers.
可选地，所述柔性基底的顶部表面具有微小空腔结构。Optionally, the top surface of the flexible substrate has a micro cavity structure.
可选地，所述微小空腔的宽度为：30μm至500μm。Optionally, the width of the micro cavity is: 30 μm to 500 μm.
可选地，所述微小空腔的深度为：0.1μm至10μm。Optionally, the depth of the micro cavity is: 0.1 μm to 10 μm.
可选地，所述微小空腔结构为三棱锥空腔阵列结构、圆锥空腔阵列结构或三棱柱空腔阵列结构。Optionally, the micro cavity structure is a triangular pyramid cavity array structure, a conical cavity array structure, or a triangular prism cavity array structure.
本发明另一方面提出一种柔性基底薄膜体声波谐振器的形成方法，包括：提供牺牲层；在所述牺牲层之上形成底部声反射层；在所述底部声反射层之上形成谐振结构；去除所述牺牲层，从而得到堆叠结构，然后将所述堆叠结构转移到柔性基底上，所述堆叠结构包括所述底部声反射层和所述谐振结构。Another aspect of the present invention provides a method for forming a flexible base film bulk acoustic wave resonator, including: providing a sacrificial layer; forming a bottom acoustic reflection layer on the sacrificial layer; and forming a resonance structure on the bottom acoustic reflection layer. Removing the sacrificial layer to obtain a stacked structure, and then transferring the stacked structure to a flexible substrate, the stacked structure including the bottom acoustic reflection layer and the resonance structure.
可选地，所述底部声反射层包括：单层低声阻抗层；或者，N组布拉格反射结构，其中N为正整数，每组所述布拉格反射结构包括低 声阻抗层和高声阻抗层。Optionally, the bottom acoustic reflection layer includes: a single layer of low acoustic impedance layer; or, N groups of Bragg reflection structures, where N is a positive integer, and each group of the Bragg reflection structures includes a low acoustic impedance layer and a high acoustic impedance layer .
可选地，所述低声阻抗层包括：环氧基树脂、聚乙二烯、氧化硅、铝、碳掺杂氧化硅、纳米多孔甲基倍半硅氧烷、纳米多孔氢倍半硅氧烷、包含甲基倍半硅氧烷和氢硅倍半环氧乙烷的纳米多孔混合物、纳米玻璃、气凝胶、干凝胶、旋涂玻璃、聚对二甲苯或SiLK。Optionally, the low acoustic impedance layer includes: epoxy-based resin, polyethylene oxide, silicon oxide, aluminum, carbon-doped silicon oxide, nanoporous methyl silsesquioxane, and nanoporous hydrogen silsesquioxane. Alkanes, nanoporous mixtures containing methylsilsesquioxane and hydrosilsesquioxane, nanoglass, aerogel, xerogel, spin-on glass, parylene or SiLK.
可选地，所述低声阻抗层的厚度小于1μm。Optionally, the thickness of the low acoustic impedance layer is less than 1 μm.
可选地，所述高声阻抗层包括：丁基合成橡胶、聚乙烯、氯丁橡胶、钨、钼、铂、钌、铱、钨钛、五氧化二钽、氧化哈、氧化铝、硅化络、碳化铌、氮化钽、碳化钛、氧化钛、碳化钒、氮化钨、氧化钨、碳化锆、类金刚石或硅掺杂的金刚石。Optionally, the high acoustic impedance layer includes: butyl synthetic rubber, polyethylene, neoprene, tungsten, molybdenum, platinum, ruthenium, iridium, tungsten-titanium, tantalum pentoxide, halo oxide, alumina, and silicide. , Niobium carbide, tantalum nitride, titanium carbide, titanium oxide, vanadium carbide, tungsten nitride, tungsten oxide, zirconium carbide, diamond-like or silicon-doped diamond.
可选地，所述高声阻抗层的厚度小于1μm。Optionally, the thickness of the high acoustic impedance layer is less than 1 μm.
可选地，所述谐振结构包括自下而上依次排列的：第一电极、第一压电层和第二电极；或者，第一电极、第一压电层、第二电极、第二压电层、第三电极；或者，第一电极、第一压电层、第二电极、解耦层、第三电极、第二压电层、第四电极。Optionally, the resonance structure includes a first electrode, a first piezoelectric layer, and a second electrode, which are sequentially arranged from bottom to top; or a first electrode, a first piezoelectric layer, a second electrode, and a second electrode. An electric layer, a third electrode; or a first electrode, a first piezoelectric layer, a second electrode, a decoupling layer, a third electrode, a second piezoelectric layer, and a fourth electrode.
可选地，所述第一压电层和/或所述第二压电层为复合压电层。Optionally, the first piezoelectric layer and / or the second piezoelectric layer are composite piezoelectric layers.
可选地，还包括：在所述柔性基底的顶部表面形成微小空腔结构。Optionally, it further comprises: forming a micro cavity structure on a top surface of the flexible substrate.
可选地，所述微小空腔的宽度为：30μm至500μm。Optionally, the width of the micro cavity is: 30 μm to 500 μm.
可选地，所述微小空腔的深度为：0.1μm至10μm。Optionally, the depth of the micro cavity is: 0.1 μm to 10 μm.
可选地，所述微小空腔结构为三棱锥空腔阵列结构、圆锥空腔阵列结构或三棱柱空腔阵列结构。Optionally, the micro cavity structure is a triangular pyramid cavity array structure, a conical cavity array structure, or a triangular prism cavity array structure.
由上可知，根据本发明实施例的柔性基底薄膜体声波谐振器以及 形成方法，第一方面，在谐振结构下方设置了底部声反射层，能够将向底部传播的声波反射回谐振结构，减少了能量损失，从而提高了器件Q值，改善了器件性能。第二方面，在将薄膜体声波谐振器转移到柔性基底上时，由于不需要在基底上加工空腔，省去了空腔制作的复杂工艺步骤，同时由于基底上没有空腔，在转移的过程中也不用对准，能够大大提高器件转移的效率，并且由于在基底上没有空腔的存在，器件与基底的接触面积更大，使得器件与基底的连接更为牢固不会发生塌陷。It can be known from the above that according to the flexible base film bulk acoustic wave resonator and the forming method of the embodiment of the present invention, in the first aspect, a bottom acoustic reflection layer is provided below the resonance structure, which can reflect the sound waves propagating to the bottom back to the resonance structure, reducing Energy loss, which increases device Q and improves device performance. In the second aspect, when the thin film bulk acoustic resonator is transferred to a flexible substrate, the cavity does not need to be processed on the substrate, so the complicated process steps of cavity fabrication are omitted, and because there is no cavity on the substrate, There is no need to align during the process, which can greatly improve the efficiency of device transfer, and because there is no cavity on the substrate, the contact area between the device and the substrate is larger, which makes the connection between the device and the substrate more secure without collapse.
附图说明BRIEF DESCRIPTION OF THE DRAWINGS
附图用于更好地理解本发明，不构成对本发明的不当限定。其中：The drawings are for better understanding of the present invention, and do not constitute an improper limitation on the present invention. among them:
图1是的薄膜体声波谐振器因弯曲过度而塌陷的示意图；1 is a schematic diagram of a thin-film bulk acoustic wave resonator collapsed due to excessive bending;
图2是本发明第一实施例的柔性基底薄膜体声波谐振器的结构示意图；2 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a first embodiment of the present invention;
图3是本发明第二实施例的柔性基底薄膜体声波谐振器的结构示意图；3 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a second embodiment of the present invention;
图4是本发明第三实施例的柔性基底薄膜体声波谐振器的结构示意图；4 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a third embodiment of the present invention;
图5A是本发明第四实施例的柔性基底薄膜体声波谐振器的结构示意图；5A is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a fourth embodiment of the present invention;
图5B至图5G是图5A所示的柔性基底薄膜体声波谐振器中位于柔性基底顶表面的微小空腔结构的细节示意图；5B to 5G are detailed schematic diagrams of the micro cavity structure on the top surface of the flexible substrate in the flexible substrate thin film bulk acoustic resonator shown in FIG. 5A;
图6是本发明第五实施例的柔性基底薄膜体声波谐振器的结构示意图；6 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a fifth embodiment of the present invention;
图7是本发明第六实施例的柔性基底薄膜体声波谐振器的结构示意图；7 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a sixth embodiment of the present invention;
图8是本发明第七实施例的柔性基底薄膜体声波谐振器的结构示意图。8 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a seventh embodiment of the present invention.
具体实施方式detailed description
下面详细描述本发明的实施例，所述实施例的示例在附图中示出，其中自始至终相同或类似的标号表示相同或类似的元件或具有相同或类似功能的元件。下面通过参考附图描述的实施例是示例性的，旨在用于解释本发明，而不能理解为对本发明的限制。Hereinafter, embodiments of the present invention will be described in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.
在本发明的描述中，需要理解的是，术语“中心”、“纵向”、“横向”、“长度”、“宽度”、“厚度”、“上”、“下”、“前”、“后”、“左”、“右”、“竖直”、“水平”、“顶”、“底”“内”、“外”、“顺时针”、“逆时针”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，因此不能理解为对本发明的限制。In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Back, left, right, vertical, horizontal, top, bottom, inner, outer, clockwise, counterclockwise, etc. The relationship is based on the orientation or position relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, structure and operation in a specific orientation. It should not be understood as a limitation on the present invention.
此外，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个该特征。在本发明的描述中，“多个”的含义是两个或两个以上，除非另有明确具体的限定。In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as “first” and “second” may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless specifically defined otherwise.
在本发明中，除非另有明确的规定和限定，术语“安装”、“相连”、“连接”、“固定”等术语应做广义理解，例如，可以是固定连接，也可以是可拆卸连接，或一体地连接；可以是机械连接，也可以是电连接；可以是直接相连，也可以通过中间媒介间接相连，可以是两个元件内部的连通。对于本领域的普通技术人员而言，可以根据具体情况理解上述术语在本发明中的具体含义。In the present invention, the terms "installation", "connected", "connected", "fixed" and other terms shall be understood in a broad sense unless otherwise specified and defined, for example, they may be fixed connections or removable connections , Or integrally connected; it can be mechanical or electrical; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.
在本发明中，除非另有明确的规定和限定，第一特征在第二特征之“上”或之“下”可以包括第一和第二特征直接接触，也可以包括第一和第二特征不是直接接触而是通过它们之间的另外的特征接触。而且，第一特征在第二特征“之上”、“上方”和“上面”包括第一特征在第二特征 正上方和斜上方，或仅仅表示第一特征水平高度高于第二特征。第一特征在第二特征“之下”、“下方”和“下面”包括第一特征在第二特征正下方和斜下方，或仅仅表示第一特征水平高度小于第二特征。In the present invention, unless specifically stated and defined otherwise, the "first" or "down" of the second feature may include the first and second features in direct contact, and may also include the first and second features. Not directly, but through another characteristic contact between them. Moreover, the first feature is "above", "above", and "above" the second feature, including that the first feature is directly above and obliquely above the second feature, or merely indicates that the first feature is higher in level than the second feature. The first feature is “below”, “below”, and “below” of the second feature, including the fact that the first feature is directly below and obliquely below the second feature, or merely indicates that the first feature is less horizontal than the second feature.
本发明的第一方面提供了柔性基底薄膜体声波谐振器。A first aspect of the present invention provides a flexible base film bulk acoustic wave resonator.
根据本发明实施例的柔性基底薄膜体声波谐振器包括：柔性基底、底部声反射层、以及谐振结构，其中：底部声反射层位于柔性基底之上；谐振结构位于底部声反射层之上。The flexible substrate thin film bulk acoustic resonator according to the embodiment of the present invention includes a flexible substrate, a bottom acoustic reflection layer, and a resonance structure, wherein: the bottom acoustic reflection layer is located on the flexible substrate; and the resonance structure is located on the bottom acoustic reflection layer.
根据本发明实施例的柔性基底薄膜体声波谐振器，在谐振结构下方设置了底部声反射层，能够将向底部传播的声波反射回谐振结构，减少了能量损失，从而提高了器件Q值，改善了器件性能。According to the flexible base film bulk acoustic wave resonator of the embodiment of the present invention, a bottom acoustic reflection layer is provided below the resonance structure, which can reflect sound waves propagating to the bottom back to the resonance structure, reduce energy loss, thereby improving the Q value of the device and improving Device performance.
其中，柔性基底可以是聚酰亚胺(PI)、聚二甲基硅氧烷(PDMS)、涤纶树脂(PET)聚碳酸酯(PC)、聚萘二甲酸乙二醇酯(PEN)、聚醚砜(PES)、聚醚酰亚胺(PEI)、聚乙烯醇(PVA)、各种含氟聚合物(FEP)等构成。Among them, the flexible substrate may be polyimide (PI), polydimethylsiloxane (PDMS), polyester resin (PET) polycarbonate (PC), polyethylene naphthalate (PEN), polymer It consists of ether sulfone (PES), polyetherimide (PEI), polyvinyl alcohol (PVA), and various fluoropolymers (FEP).
其中，底部声反射层可以包括：单层低声阻抗层；或者，N组布拉格反射结构，N为正整数，每组布拉格反射结构包括低声阻抗层和高声阻抗层。其中低声阻抗层和高声阻抗层的厚度均为四分之一或四分之三声波波长。当底部声反射层仅仅包含单层低声阻抗层时，器件具有更轻薄、柔韧性更好的优点。当底部声反射层包含多组布拉格反射结构时，声波反射效果更佳。当底部声层包含单组布拉格反射结构时，器件轻薄柔韧的特性适中，声波反射效果也适中。The bottom acoustic reflection layer may include: a single layer of low acoustic impedance layer; or N groups of Bragg reflection structures, where N is a positive integer, and each group of Bragg reflection structures includes a low acoustic impedance layer and a high acoustic impedance layer. The thickness of the low acoustic impedance layer and the high acoustic impedance layer are both one-quarter or three-quarter the wavelength of the acoustic wave. When the bottom acoustic reflection layer contains only a single low acoustic impedance layer, the device has the advantages of being thinner and more flexible. When the bottom acoustic reflection layer contains multiple sets of Bragg reflection structures, the sound wave reflection effect is better. When the bottom acoustic layer contains a single group of Bragg reflection structures, the device is moderately thin and flexible, and the acoustic reflection effect is also moderate.
需要说明的是，低声阻抗层由低声阻抗材料组成，可以是氧化硅、铝、碳掺杂氧化硅、纳米多孔甲基倍半硅氧烷、纳米多孔氢倍半硅氧烷、包含甲基倍半硅氧烷(methyl silsesquioxane，简称MSQ)和氢硅 倍半环氧乙烷(hydrogen silsesquioxane，简称HSQ)的纳米多孔混合物、纳米玻璃、气凝胶、干凝胶、旋涂玻璃、聚对二甲苯、SiLK(SiLK是Dow Chemical公司开发的一种低介电常数材料，目前广泛用于集成电路生产。目前已知它是一种高分子材料，但是具体结构仍然是商业秘密)或苯并环丁烯。低声阻抗层的厚度小于1μm，由于它是很薄的薄膜，可以增加器件的柔性。It should be noted that the low acoustic impedance layer is composed of a low acoustic impedance material, which may be silicon oxide, aluminum, carbon-doped silicon oxide, nanoporous methylsilsesquioxane, nanoporous hydrogen silsesquioxane, containing formazan Nanoporous mixtures of methylsilsesquioxane (MSQ) and hydrogen silsesquioxane (HSQ), nanoglasses, aerogels, xerogels, spin-on glass, polymer Paraxylene, SiLK (SiLK is a low dielectric constant material developed by Dow Chemical Company and is currently widely used in integrated circuit production. It is currently known as a polymer material, but the specific structure is still a trade secret) or benzene And cyclobutene. The thickness of the low acoustic impedance layer is less than 1 μm. Since it is a thin film, it can increase the flexibility of the device.
高声阻抗层由高声阻材料组成，可以是钨、钼、铂、钌、铱、钨钛、五氧化二钽、氧化哈、氧化铝、硅化络、碳化铌、氮化钽、碳化钛、氧化钛、碳化钒、氮化钨、氧化钨、碳化锆、类金刚石或硅掺杂的金刚石。优选地，底部声反射层全部都采用柔性材料，这样能够有效提高器件的柔韧性、弯曲性，使其能够适应更加复杂的环境。具体地，低声阻抗层可以包括环氧基树脂或聚乙二烯。高声阻抗层包括丁基合成橡胶、聚乙烯或氯丁橡胶。需要说明的是，低声阻抗层和高声阻抗层，既可以是上述几种特定材料的纯的高分子柔性材料，也可以为包含这几种特定材料的复合柔性材料。高声阻抗层的厚度小于1μm，由于它是很薄的薄膜，可以增加器件的柔性。The high acoustic impedance layer is composed of a high acoustic resistance material, which can be tungsten, molybdenum, platinum, ruthenium, iridium, tungsten titanium, tantalum pentoxide, halo oxide, alumina, silicide, niobium carbide, tantalum nitride, titanium carbide, Titanium oxide, vanadium carbide, tungsten nitride, tungsten oxide, zirconium carbide, diamond-like or silicon-doped diamond. Preferably, the bottom acoustic reflection layer is all made of a flexible material, which can effectively improve the flexibility and bendability of the device and enable it to adapt to more complicated environments. Specifically, the low acoustic impedance layer may include an epoxy-based resin or polyethylene. The high acoustic impedance layer includes butyl synthetic rubber, polyethylene, or neoprene. It should be noted that the low acoustic impedance layer and the high acoustic impedance layer may be either pure polymer flexible materials of the above-mentioned specific materials, or composite flexible materials including these specific materials. The thickness of the high acoustic impedance layer is less than 1 μm. Since it is a thin film, the flexibility of the device can be increased.
其中，谐振结构的具体形式是灵活多样的。谐振结构可以是最简单的三明治结构，包括自下而上依次排列的第一电极、第一压电层和第二电极。谐振结构也可以是“3+2”夹心结构，包括自下而上依次排列的第一电极、第一压电层、第二电极、第二压电层、第三电极。谐振结构还可以是两个垂直方向堆叠的三明治结构，包括自下而上依次排列的第一电极、第一压电层、第二电极、解耦层、第三电极、第二压电层、第四电极。需要说明的是，电极材料可以为金(Au)、钨(W)、钼(Mo)、铂(Pt)，钌(Ru)、铱(Ir)、铝(Al)、钛(Ti)等金属以及它们的合金。压电层材料可以为氮化铝(AlN)、氧化锌(ZnO)、锆钛酸铅(PZT)、铌酸锂(LiNbO 3)、石英(Quartz)、铌酸钾(KNbO 3)或钽酸锂(LiTaO 3)等材料以及它们的组合。 Among them, the specific form of the resonance structure is flexible and diverse. The resonance structure may be the simplest sandwich structure, including a first electrode, a first piezoelectric layer, and a second electrode arranged in order from bottom to top. The resonance structure may also be a "3 + 2" sandwich structure, which includes a first electrode, a first piezoelectric layer, a second electrode, a second piezoelectric layer, and a third electrode arranged in order from bottom to top. The resonance structure may also be a sandwich structure stacked in two vertical directions, including a first electrode, a first piezoelectric layer, a second electrode, a decoupling layer, a third electrode, a second piezoelectric layer, Fourth electrode. It should be noted that the electrode material may be metals such as gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), aluminum (Al), and titanium (Ti). And their alloys. The material of the piezoelectric layer can be aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO 3 ), quartz (Quartz), potassium niobate (KNbO 3 ), or tantalic acid. Materials such as lithium (LiTaO 3 ) and combinations thereof.
需要说明的是，压电层可以为常规的单一材料层之外，还可以为复合压电层。换言之，第一压电层和/或第二压电层为复合压电层。复合压电层由两种压电材料交替排列以达到整体较厚的目的，如两种压电材料可以为AlN/AlGaN也可以为其它的压电材料。复合压电层比起单一压电层，能够起到避免生长较厚的压电材料时因晶格缺陷如位错、滑移等所产生应力作用。It should be noted that the piezoelectric layer may be a conventional single material layer or a composite piezoelectric layer. In other words, the first piezoelectric layer and / or the second piezoelectric layer are composite piezoelectric layers. The composite piezoelectric layer is alternately arranged by two piezoelectric materials to achieve the purpose of being relatively thick. For example, the two piezoelectric materials may be AlN / AlGaN or other piezoelectric materials. Compared with a single piezoelectric layer, a composite piezoelectric layer can avoid stress caused by lattice defects such as dislocations and slippage when growing thicker piezoelectric materials.
可选地，柔性基底的顶部表面具有微小空腔结构。通过在柔性基底上设置一系列微小的空腔结构，能够有效地增加基底对谐振器部分声波反射的能力，进而可以减少底部声反射层的厚度，从而能够有效提高器件的柔韧性、弯曲性，使其能够适应更加复杂的环境，同时这些微小的空腔结构也能够增加器件与基底之间连接的牢固性，能够有效防止器件的脱落。微小空腔结构可以为三棱锥空腔阵列结构、圆锥空腔阵列结构或三棱柱空腔阵列结构。微小空腔的宽度要控制在合适的范围之内，如果太宽会使得谐振器完全落入空腔之内与基底相接触，同时微小空腔的深度也要控制在合适范围之内，如果太浅器件在弯曲的过程中容易与底部相接触。微小空腔的宽度可以为：30μm至500μm，典型的可以为100μm；微小空腔的深度可以为：0.1μm至10μm，典型的可以为1μm。Optionally, the top surface of the flexible substrate has a micro cavity structure. By setting a series of tiny cavity structures on a flexible substrate, the substrate's ability to reflect sound waves from the resonator can be effectively increased, and the thickness of the bottom acoustic reflection layer can be reduced, which can effectively improve the flexibility and bendability of the device. It can adapt to more complicated environment, meanwhile, these tiny cavity structures can also increase the firmness of the connection between the device and the substrate, and can effectively prevent the device from falling off. The micro cavity structure may be a triangular pyramid cavity array structure, a conical cavity array structure, or a triangular prism cavity array structure. The width of the micro-cavity should be controlled within a suitable range. If it is too wide, the resonator will completely fall into the cavity and contact the substrate. At the same time, the depth of the micro-cavity should also be controlled within a suitable range. Shallow devices easily come into contact with the bottom during the bending process. The width of the micro-cavities can be: 30 μm to 500 μm, typically 100 μm; the depth of the micro-cavities can be: 0.1 μm to 10 μm, typically 1 μm.
本发明第二方面提供了柔性基底薄膜体声波谐振器的形成方法。A second aspect of the present invention provides a method for forming a flexible base film bulk acoustic wave resonator.
根据本发明实施例的柔性基底薄膜体声波谐振器的形成方法，包括：提供牺牲层；在牺牲层之上形成底部声反射层；在底部声反射层之上形成谐振结构；去除牺牲层，从而得到堆叠结构，然后将堆叠结构转移到柔性基底上，堆叠结构包括底部声反射层和谐振结构。A method for forming a flexible base film bulk acoustic wave resonator according to an embodiment of the present invention includes: providing a sacrificial layer; forming a bottom acoustic reflection layer on the sacrificial layer; forming a resonance structure on the bottom acoustic reflection layer; removing the sacrificial layer, thereby A stacked structure is obtained, and then the stacked structure is transferred to a flexible substrate. The stacked structure includes a bottom acoustic reflection layer and a resonance structure.
根据本发明实施例的柔性基底薄膜体声波谐振器的形成方法，第一方面，在谐振结构下方设置了底部声反射层，能够将向底部传播的声波反射回谐振结构，减少了能量损失，从而提高了器件Q值，改善 了器件性能。第二方面，在将薄膜体声波谐振器转移到柔性基底上时，由于不需要在基底上加工空腔，省去了空腔制作的复杂工艺步骤，同时由于基底上没有空腔，在转移的过程中也不用对准，能够大大提高器件转移的效率，并且由于在基底上没有空腔的存在，器件与基底的接触面积更大，使得器件与基底的连接更为牢固不会发生塌陷。According to the method for forming a flexible base film bulk acoustic wave resonator according to an embodiment of the present invention, in a first aspect, a bottom acoustic reflection layer is provided below the resonance structure, and a sound wave propagating toward the bottom can be reflected back to the resonance structure, thereby reducing energy loss, thereby Improved device Q value and improved device performance. In the second aspect, when the thin film bulk acoustic resonator is transferred to a flexible substrate, the cavity does not need to be processed on the substrate, so the complicated process steps of cavity fabrication are omitted, and because there is no cavity on the substrate, There is no need to align during the process, which can greatly improve the efficiency of device transfer, and because there is no cavity on the substrate, the contact area between the device and the substrate is larger, which makes the connection between the device and the substrate more secure without collapse.
其中，底部声反射层可以包括：单层低声阻抗层；或者，N层布拉格反射结构，N为正整数，每组布拉格反射结构包括低声阻抗层和高声阻抗层。其中低声阻抗层和高声阻抗层的厚度均为四分之一或四分之三声波波长。当底部声反射层仅仅包含单层低声阻抗层时，器件具有更轻薄、柔韧性更好的优点。当底部声反射层包含多组布拉格反射结构时，声波反射效果更佳。当底部声反射层包含单组布拉格反射结构时，器件轻薄柔韧的特性适中，声波反射效果也适中。The bottom acoustic reflection layer may include: a single layer of low acoustic impedance layer; or N-layer Bragg reflection structures, where N is a positive integer, and each group of Bragg reflection structures includes a low acoustic impedance layer and a high acoustic impedance layer. The thickness of the low acoustic impedance layer and the high acoustic impedance layer are both one-quarter or three-quarter the wavelength of the acoustic wave. When the bottom acoustic reflection layer contains only a single low acoustic impedance layer, the device has the advantages of being thinner and more flexible. When the bottom acoustic reflection layer contains multiple sets of Bragg reflection structures, the sound wave reflection effect is better. When the bottom acoustic reflection layer contains a single group of Bragg reflection structures, the characteristics of the device are moderately thin and flexible, and the acoustic reflection effect is also moderate.
其中，低声阻抗层由低声阻抗材料组成，通常可以是氧化硅、铝、碳掺杂氧化硅、纳米多孔甲基倍半硅氧烷、纳米多孔氢倍半硅氧烷、包含甲基倍半硅氧烷(methyl silsesquioxane，简称MSQ)和氢硅倍半环氧乙烷(hydrogen silsesquioxane，简称HSQ)的纳米多孔混合物、纳米玻璃、气凝胶、干凝胶、旋涂玻璃、聚对二甲苯、SiLK(SiLK是Dow Chemical公司开发的一种低介电常数材料，目前广泛用于集成电路生产。目前已知它是一种高分子材料，但是具体结构仍然是商业秘密)或苯并环丁烯。低声阻抗层的厚度小于1μm，由于它是很薄的薄膜，可以增加器件的柔性。Among them, the low acoustic impedance layer is composed of a low acoustic impedance material, which can usually be silicon oxide, aluminum, carbon-doped silicon oxide, nanoporous methyl silsesquioxane, nano porous hydrogen silsesquioxane, and methyl silsesquioxane. Nanoporous mixtures of methylsilsesquioxane (MSQ) and hydrogen silsesquioxane (HSQ), nanoglasses, aerogels, xerogels, spin-on glass, polyisocyanate Toluene, SiLK (SiLK is a low dielectric constant material developed by Dow Chemical Company and is currently widely used in integrated circuit production. It is currently known as a polymer material, but the specific structure is still a trade secret) or a benzo ring Butene. The thickness of the low acoustic impedance layer is less than 1 μm. Since it is a thin film, it can increase the flexibility of the device.
其中，高声阻抗层由高声阻材料组成，通常可以是钨、钼、铂、钌、铱、钨钛、五氧化二钽、氧化哈、氧化铝、硅化络、碳化铌、氮化钽、碳化钛、氧化钛、碳化钒、氮化钨、氧化钨、碳化锆、类金刚石或硅掺杂的金刚石。高声阻抗层的厚度小于1μm，由于它是很薄的薄膜，可以增加器件的柔性。Among them, the high acoustic impedance layer is composed of a high acoustic resistance material, which can usually be tungsten, molybdenum, platinum, ruthenium, iridium, tungsten titanium, tantalum pentoxide, halo oxide, alumina, silicide, niobium carbide, tantalum nitride, Titanium carbide, titanium oxide, vanadium carbide, tungsten nitride, tungsten oxide, zirconium carbide, diamond-like or silicon-doped diamond. The thickness of the high acoustic impedance layer is less than 1 μm. Since it is a thin film, the flexibility of the device can be increased.
优选地，底部声反射层全部都采用高分子柔性材料，这样能够有效提高器件的柔韧性、弯曲性，使其能够适应更加复杂的环境。具体地，低声阻抗层可以包括环氧基树脂或聚乙二烯。高声阻抗层包括丁基合成橡胶、聚乙烯或氯丁橡胶。需要说明的是，低声阻抗层和高声阻抗层，既可以是上述几种特定材料的纯的高分子柔性材料，也可以为包含这几种特定材料的复合柔性材料。Preferably, the bottom acoustic reflection layer is all made of a polymer flexible material, which can effectively improve the flexibility and bendability of the device and enable it to adapt to more complicated environments. Specifically, the low acoustic impedance layer may include an epoxy-based resin or polyethylene. The high acoustic impedance layer includes butyl synthetic rubber, polyethylene, or neoprene. It should be noted that the low acoustic impedance layer and the high acoustic impedance layer may be either pure polymer flexible materials of the above-mentioned specific materials, or composite flexible materials including these specific materials.
其中，谐振结构的具体形式是灵活多样的。谐振结构可以是最简单的三明治结构，包括自下而上依次排列的第一电极、第一压电层和第二电极。谐振结构也可以是“3+2”夹心结构，包括自下而上依次排列的第一电极、第一压电层、第二电极、第二压电层、第三电极。谐振结构还可以是两个垂直方向堆叠的三明治结构，包括自下而上依次排列的第一电极、第一压电层、第二电极、解耦层、第三电极、第二压电层、第四电极。需要说明的是，电极材料可以为金(Au)、钨(W)、钼(Mo)、铂(Pt)，钌(Ru)、铱(Ir)、铝(Al)、钛(Ti)等金属以及它们的合金。压电层材料可以为氮化铝(AlN)、氧化锌(ZnO)、锆钛酸铅(PZT)、铌酸锂(LiNbO 3)、石英(Quartz)、铌酸钾(KNbO 3)或钽酸锂(LiTaO 3)等材料以及它们的组合。 Among them, the specific form of the resonance structure is flexible and diverse. The resonance structure may be the simplest sandwich structure, including a first electrode, a first piezoelectric layer, and a second electrode arranged in order from bottom to top. The resonance structure may also be a "3 + 2" sandwich structure, which includes a first electrode, a first piezoelectric layer, a second electrode, a second piezoelectric layer, and a third electrode arranged in order from bottom to top. The resonance structure may also be a sandwich structure stacked in two vertical directions, including a first electrode, a first piezoelectric layer, a second electrode, a decoupling layer, a third electrode, a second piezoelectric layer, Fourth electrode. It should be noted that the electrode material may be metals such as gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), aluminum (Al), and titanium (Ti). And their alloys. The material of the piezoelectric layer can be aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium niobate (LiNbO 3 ), quartz (Quartz), potassium niobate (KNbO 3 ), or tantalic acid. Materials such as lithium (LiTaO 3 ) and combinations thereof.
需要说明的是，压电层可以为常规的单一材料层之外，还可以为复合压电层。换言之，第一压电层和/或第二压电层为复合压电层。复合压电层由两种压电材料交替排列以达到整体较厚的目的，如两种压电材料可以为AlN/AlGaN也可以为其它的压电材料。复合压电层比起单一压电层，能够起到避免生长较厚的压电材料时因晶格缺陷如位错、滑移等所产生应力作用。It should be noted that the piezoelectric layer may be a conventional single material layer or a composite piezoelectric layer. In other words, the first piezoelectric layer and / or the second piezoelectric layer are composite piezoelectric layers. The composite piezoelectric layer is alternately arranged by two piezoelectric materials to achieve the purpose of being relatively thick. For example, the two piezoelectric materials may be AlN / AlGaN or other piezoelectric materials. Compared with a single piezoelectric layer, a composite piezoelectric layer can avoid stress caused by lattice defects such as dislocations and slippage when growing thicker piezoelectric materials.
可选地，柔性基底的顶部表面具有微小空腔结构。通过在柔性基底上设置一系列微小的空腔结构，能够有效地增加基底对谐振器部分声波反射的能力，进而可以减少底部声反射层的厚度，从而能够有效提高器件的柔韧性、弯曲性，使其能够适应更加复杂的环境，同时这 些微小的空腔结构也能够增加器件与基底之间连接的牢固性，能够有效防止器件的脱落。微小空腔结构可以为三棱锥空腔阵列结构、圆锥空腔阵列结构或三棱柱空腔阵列结构。微小空腔的宽度要控制在合适的范围之内，如果太宽会使得谐振器完全落入空腔之内与基底相接触，同时微小空腔的深度也要控制在合适范围之内，如果太浅器件在弯曲的过程中容易与底部相接触。微小空腔的宽度可以为：30μm至500μm，典型的可以为100μm；微小空腔的深度可以为：0.1μm至10μm，典型的可以为1μm。Optionally, the top surface of the flexible substrate has a micro cavity structure. By setting a series of tiny cavity structures on a flexible substrate, the substrate's ability to reflect sound waves from the resonator can be effectively increased, and the thickness of the bottom acoustic reflection layer can be reduced, which can effectively improve the flexibility and bendability of the device. It can adapt to more complicated environment, meanwhile, these tiny cavity structures can also increase the firmness of the connection between the device and the substrate, and can effectively prevent the device from falling off. The micro cavity structure may be a triangular pyramid cavity array structure, a conical cavity array structure, or a triangular prism cavity array structure. The width of the micro-cavity should be controlled within a suitable range. If it is too wide, the resonator will completely fall into the cavity and contact the substrate. At the same time, the depth of the micro-cavity should also be controlled within a suitable range. Shallow devices easily come into contact with the bottom during the bending process. The width of the micro-cavities can be: 30 μm to 500 μm, typically 100 μm; the depth of the micro-cavities can be: 0.1 μm to 10 μm, typically 1 μm.
为使本领域技术人员更好地理解本发明，下面列举多个具体实施例进行说明。To enable those skilled in the art to better understand the present invention, a plurality of specific embodiments are described below for description.
图2是本发明第一实施例的柔性基底薄膜体声波谐振器的结构示意图。在此典型实施例中，柔性薄膜体声波谐振器(FBAR)200的制作过程包括：首先在硅基底上刻蚀形成空腔并沉积一层牺牲材料，通过化学机械平坦化使其表面光滑平整，形成牺牲层；沉积包括两组布拉格反射结构的底部声反射层，包括高声阻抗层213和209以及低声阻抗层211和207；沉积第一电极205；沉积压电层203；沉积第二电极201；然后将牺牲层去除；然后，通过转移的方法，在显微操作下，将在硅基底上制备好的带有布拉格反射结构的FBAR提起，并将其放置到柔性基底215上，从而形成柔性薄膜体声波谐振器。其中，第一电极205、压电层203和第二电极201，在垂直方向上的重叠区域为谐振器的有效区域。当在第一电极205和第二电极201之间施加一定频率的交变电压信号时，由于压电材料所具有的逆压电效应，有效区域内的上下电极之间会产生垂直方向传播的声波，声波将会在第二电极201与空气的交界面以及第一电极205下的布拉格反射结构结构之间来回反射并在一定频率下产生谐振。该实施例中，在将薄膜体声波谐振器转移到柔性基底上时，由于不需要在基底上加工空腔，省去了空腔制作的复杂工艺步骤，同时由于基底上没有空腔，在转移的过程中也不用对准，能够大大提高器件转移的效率，并且由于在基底上没有空 腔的存在，器件与基底的接触面积更大，使得器件与基底的连接更为牢固不会发生塌陷。FIG. 2 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a first embodiment of the present invention. In this exemplary embodiment, the manufacturing process of the flexible thin film bulk acoustic wave resonator (FBAR) 200 includes: firstly etching a silicon substrate to form a cavity and depositing a layer of sacrificial material, and smoothing and smoothing its surface through chemical mechanical planarization, Forming a sacrificial layer; depositing a bottom acoustic reflection layer including two sets of Bragg reflecting structures, including high acoustic impedance layers 213 and 209 and low acoustic impedance layers 211 and 207; depositing a first electrode 205; depositing a piezoelectric layer 203; depositing a second electrode 201; then the sacrificial layer is removed; then, by a transfer method, under a micro operation, the FBAR with a Bragg reflection structure prepared on a silicon substrate is lifted and placed on a flexible substrate 215 to form Flexible thin film bulk acoustic resonator. The vertical region of the first electrode 205, the piezoelectric layer 203, and the second electrode 201 is the effective region of the resonator. When an alternating voltage signal of a certain frequency is applied between the first electrode 205 and the second electrode 201, due to the inverse piezoelectric effect of the piezoelectric material, a sound wave propagating vertically is generated between the upper and lower electrodes in the effective area. The sound wave will be reflected back and forth between the interface between the second electrode 201 and the air and the Bragg reflection structure under the first electrode 205 and resonate at a certain frequency. In this embodiment, when the thin-film bulk acoustic wave resonator is transferred to a flexible substrate, since the cavity does not need to be processed on the substrate, the complicated process steps of making the cavity are omitted, and since there is no cavity on the substrate, the transfer There is no need to align during the process, which can greatly improve the efficiency of device transfer, and because there is no cavity on the substrate, the contact area between the device and the substrate is larger, which makes the connection between the device and the substrate more secure without collapse.
图3是本发明第二实施例的柔性基底薄膜体声波谐振器的结构示意图。在此典型实施例中，柔性薄膜体声波谐振器(FBAR)300的制作过程包括：沉积一层牺牲层；沉积包括单组布拉格反射结构的底部声反射层，包括高声阻抗层309和低声阻抗层307；沉积第一电极305；沉积压电层303；沉积第二电极301；去除牺牲层；然后，通过转移的方法，在显微操作下，将在硅基底上制备好的带有布拉格反射结构的FBAR提起，并将其放置到柔性基底311上，从而形成柔性薄膜体声波谐振器。这样减少了布拉格反射结构的数量，使得器件的柔韧性及弯曲性能增加，能够使其适应更加复杂的环境。3 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a second embodiment of the present invention. In this exemplary embodiment, the manufacturing process of the flexible thin film bulk acoustic resonator (FBAR) 300 includes: depositing a sacrificial layer; depositing a bottom acoustic reflective layer including a single set of Bragg reflective structures, including a high acoustic impedance layer 309 and a low acoustic Resistive layer 307; deposition of first electrode 305; deposition of piezoelectric layer 303; deposition of second electrode 301; removal of sacrificial layer; and then, using a transfer method and under a microscopic operation, a Bragg with silicon substrate is prepared. The FBAR of the reflective structure is lifted and placed on the flexible substrate 311 to form a flexible thin film bulk acoustic resonator. This reduces the number of Bragg reflective structures, increases the flexibility and bending performance of the device, and enables it to adapt to more complex environments.
图4是本发明第三实施例的柔性基底薄膜体声波谐振器的结构示意图。在此典型实施例中，柔性薄膜体声波谐振器(FBAR)400的制作过程包括：沉积一层牺牲层；沉积底部声反射层，只包括一层低声阻抗层407；沉积第一电极405；沉积压电层403；沉积第二电极401；去除牺牲层；然后，通过转移的方法，在显微操作下，将在硅基底上制备好的带有布拉格反射结构的FBAR提起，并将其放置到柔性基底409上，从而形成柔性薄膜体声波谐振器。其中，布拉格反射结构只包含一层低声阻抗层407，其中低声阻抗层选择声阻抗尽量接近与零的材料，这样在保障声波反射能力的同时，进一步减化了底部声反射层的结构，使得器件的柔韧性及弯曲性能进一步增加，使其能够适应更加复杂的环境。FIG. 4 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a third embodiment of the present invention. In this exemplary embodiment, the manufacturing process of the flexible thin film bulk acoustic resonator (FBAR) 400 includes: depositing a sacrificial layer; depositing a bottom acoustic reflection layer including only a low acoustic impedance layer 407; depositing a first electrode 405; Deposition the piezoelectric layer 403; deposit the second electrode 401; remove the sacrificial layer; and then, by a transfer method, under a micro operation, lift the FBAR prepared with a Bragg reflection structure on a silicon substrate and place it Onto a flexible substrate 409 to form a flexible thin film bulk acoustic resonator. Among them, the Bragg reflection structure only includes a layer of low acoustic impedance layer 407, and the low acoustic impedance layer selects a material whose acoustic impedance is as close to zero as possible, so as to ensure the sound wave reflection ability, and further reduce the structure of the bottom acoustic reflection layer, The device's flexibility and bending performance are further increased, enabling it to adapt to more complex environments.
图5A是本发明第四实施例的柔性基底薄膜体声波谐振器的结构示意图。在此典型实施例中，柔性薄膜体声波谐振器(FBAR)500的制作过程包括：沉积一层牺牲层；沉积包括单组布拉格反射结构的底部声反射层，即高声阻抗层509和低声阻抗层507；沉积第一电极505；沉积压电层503；沉积第二电极501；去除牺牲层；然后，通过转移的 方法，在显微操作下，将在硅基底上制备好的带有布拉格反射结构的FBAR提起，并将其放置到柔性基底511上，从而形成柔性薄膜体声波谐振器。其中，柔性基底通过倒模或者其它类似的工艺方法，制作出表面具有一系列微小空腔结构，其可以为多个三棱锥(5E)、圆锥(5F)或三棱柱(5G)或着其他相类似的结构的单元而成排成阵列，形成的基底顶表面分别如图5B、5C或5D所示。微小空腔的宽度可以为：30μm至500μm，典型的可以为100μm；微小空腔的深度可以为：0.1μm至10μm，典型的可以为1μm。该实施例中，通过在柔性基底上制作形成的一系列微小的空腔结构，能够有效地增加基底对谐振结构声波反射的能力，进而可以减少布拉格反射结构的数量，从而能够有效提高器件的柔韧性、弯曲性，使其能够适应更加复杂的环境，同时这些微小的空腔结构也能够增加器件与基底之间连接的牢固性，能够有效防止器件的脱落。5A is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a fourth embodiment of the present invention. In this exemplary embodiment, the manufacturing process of the flexible thin film bulk acoustic resonator (FBAR) 500 includes: depositing a sacrificial layer; depositing a bottom acoustic reflective layer including a single set of Bragg reflective structures, namely a high acoustic impedance layer 509 and a low acoustic Resistive layer 507; deposition of first electrode 505; deposition of piezoelectric layer 503; deposition of second electrode 501; removal of sacrificial layer; and then, by transfer method, under micro-operation, a Bragg with silicon substrate is prepared. The FBAR of the reflective structure is lifted and placed on the flexible substrate 511 to form a flexible thin film bulk acoustic resonator. Among them, the flexible substrate is produced by inverted mold or other similar process methods to have a series of microcavity structures on the surface, which can be multiple triangular pyramids (5E), cones (5F) or triangular prisms (5G) or other phases. The cells of similar structure are arranged in an array, and the top surfaces of the formed substrates are respectively shown in FIG. 5B, 5C, or 5D. The width of the micro-cavities can be: 30 μm to 500 μm, typically 100 μm; the depth of the micro-cavities can be: 0.1 μm to 10 μm, typically 1 μm. In this embodiment, a series of tiny cavity structures formed on the flexible substrate can effectively increase the substrate's ability to reflect the acoustic waves of the resonant structure, thereby reducing the number of Bragg reflective structures, and thus effectively improving the flexibility of the device. The flexibility and flexibility make it able to adapt to more complex environments. At the same time, these tiny cavity structures can also increase the firmness of the connection between the device and the substrate, and can effectively prevent the device from falling off.
图6是本发明第五实施例的柔性基底薄膜体声波谐振器的结构示意图。在此典型实施例中，柔性堆叠式薄膜体声波谐振器600的制作过程包括：沉积一层牺牲层；沉积包括单组布拉格反射结构的底部声反射层，即包括高声阻抗层613和低声阻抗层611；沉积第一电极609；沉积第一压电层607；沉积第二电极605；沉积第二压电层603；沉积第三电极601；去除牺牲层；然后，通过转移的方法，在显微操作下，将在硅基底上制备好的带有布拉格反射结构堆叠式薄膜体声波谐振器提起，并将其放置到柔性基底615上，从而形成柔性堆叠式体声波谐振器。该实施例的制作方法可以获得连接牢固、声反射能力较强、具有较好的柔性和弯曲特性的堆叠式体声波谐振器。FIG. 6 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a fifth embodiment of the present invention. In this exemplary embodiment, the manufacturing process of the flexible stacked thin-film bulk acoustic wave resonator 600 includes: depositing a sacrificial layer; depositing a bottom acoustic reflection layer including a single group of Bragg reflective structures, that is, including a high acoustic impedance layer 613 and a low acoustic wave Resistance layer 611; deposition of first electrode 609; deposition of first piezoelectric layer 607; deposition of second electrode 605; deposition of second piezoelectric layer 603; deposition of third electrode 601; removal of the sacrificial layer; Under a microscopic operation, a stacked thin film bulk acoustic wave resonator with a Bragg reflection structure prepared on a silicon substrate is lifted and placed on a flexible substrate 615 to form a flexible stacked bulk acoustic wave resonator. The manufacturing method of this embodiment can obtain a stacked bulk acoustic wave resonator with firm connection, strong acoustic reflection ability, and good flexibility and bending characteristics.
图7是本发明第六实施例的柔性基底薄膜体声波谐振器的结构示意图。在此典型实施例中，柔性耦合谐振滤波器700的制作过程包括：沉积一层牺牲层；沉积包括单组布拉格反射结构的底部声反射层，包括高声阻抗层718和低声阻抗层715；沉积第一底部电极713；沉积第一压电层711；沉积第一顶部电极709；沉积解耦层707；沉积第二底 部电极705；沉积第二压电层703；沉积第二顶部电极701；去除牺牲层；然后，通过转移的方法，在显微操作下，将在硅基底上制备好的带有布拉格反射结构耦合谐振滤波器提起，并将其放置到柔性基底721上，从而形成柔性堆叠式体声波谐振器。该实施例的制作方法可以获得连接牢固、声反射能力较强、具有较好的柔性和弯曲特性的堆叠式体声波谐振器。FIG. 7 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a sixth embodiment of the present invention. In this exemplary embodiment, the manufacturing process of the flexible coupling resonant filter 700 includes: depositing a sacrificial layer; depositing a bottom acoustic reflection layer including a single set of Bragg reflection structures, including a high acoustic impedance layer 718 and a low acoustic impedance layer 715; Deposit first bottom electrode 713; deposit first piezoelectric layer 711; deposit first top electrode 709; deposit decoupling layer 707; deposit second bottom electrode 705; deposit second piezoelectric layer 703; deposit second top electrode 701; The sacrificial layer is removed; then, by a transfer method, under a micro operation, the coupled resonant filter with a Bragg reflection structure prepared on a silicon substrate is lifted and placed on a flexible substrate 721 to form a flexible stack Type bulk acoustic wave resonator. The manufacturing method of this embodiment can obtain a stacked bulk acoustic wave resonator with firm connection, strong acoustic reflection ability, and good flexibility and bending characteristics.
图8是本发明第七实施例的柔性基底薄膜体声波谐振器的结构示意图。在此典型实施例中，柔性薄膜体声波谐振器(FBAR)800的制作过程包括：首先在单晶硅基底上加工出带有布拉格反射结构的FBAR，其制造顺序依次为：沉积一层牺牲层；沉积包括单组布拉格反射结构的底部声反射层，包括高声阻抗层813和低声阻抗层811；沉积第一电极809；沉积压电层，压电层由两种压电材料交替生长以达到整体较厚的目的，如两种压电材料可以为AlN/AlGaN也可以为其它的压电材料，其中第一层压电材料层807为AlN，第二层压电材料层805为AlGaN，如此交替反复生长，直至最后一层压电材料层803为AlGaN。其中，生长的AlGaN厚度较厚，单层厚度约1至10μm，生长的AlN层的厚度较薄，单层厚度约10至30纳米，这样能够起到弥补生长较厚的AlGaN因晶格缺陷如位错、滑移等所产生的应力作用；沉积第二电极801；去除牺牲层；然后，通过转移的方法，在显微操作下，将在硅基底上制备好的带有布拉格反射结构的FBAR提起，并将其放置到柔性基底815上，从而形成柔性薄膜体声波谐振器。该实施例的制作方法可以获得压电层较厚的柔性薄膜体声波谐振器，同时其连接牢固性、弯曲性、柔韧性都很可靠。8 is a schematic structural diagram of a flexible base film bulk acoustic wave resonator according to a seventh embodiment of the present invention. In this exemplary embodiment, the manufacturing process of a flexible thin film bulk acoustic wave resonator (FBAR) 800 includes: firstly processing a FBAR with a Bragg reflection structure on a single crystal silicon substrate, and the manufacturing sequence is: depositing a sacrificial layer ; Deposit a bottom acoustic reflection layer including a single set of Bragg reflective structures, including a high acoustic impedance layer 813 and a low acoustic impedance layer 811; deposit a first electrode 809; deposit a piezoelectric layer, and the piezoelectric layer is alternately grown from two piezoelectric materials to To achieve a thicker overall, for example, the two piezoelectric materials can be AlN / AlGaN or other piezoelectric materials, where the first piezoelectric material layer 807 is AlN and the second piezoelectric material layer 805 is AlGaN. This alternately and repeatedly grows until the last piezoelectric material layer 803 is AlGaN. Among them, the thickness of the grown AlGaN is thicker, the thickness of the single layer is about 1 to 10 μm, the thickness of the grown AlN layer is thinner, and the thickness of the single layer is about 10 to 30 nanometers. This can make up for the growth of thicker AlGaN due to lattice defects such as The stress caused by dislocations, slippage, etc .; depositing the second electrode 801; removing the sacrificial layer; and then, using a transfer method, under a micro operation, a FBAR with a Bragg reflection structure will be prepared on a silicon substrate Lift and place it on the flexible substrate 815 to form a flexible thin film bulk acoustic resonator. The manufacturing method of this embodiment can obtain a flexible thin film bulk acoustic wave resonator with a thick piezoelectric layer, and at the same time, its connection firmness, bendability and flexibility are reliable.
上述具体实施方式，并不构成对本发明保护范围的限制。本领域技术人员应该明白的是，取决于设计要求和其他因素，可以发生各种各样的修改、组合、子组合和替代。任何在本发明的精神和原则之内所作的修改、等同替换和改进等，均应包含在本发明保护范围之内。The foregoing specific implementation manners do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations, and substitutions may occur depending on design requirements and other factors. Any modification, equivalent replacement and improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (24)

  1. 一种柔性基底薄膜体声波谐振器，其特征在于，包括：柔性基底、底部声反射层、以及谐振结构，其中：所述底部声反射层位于所述柔性基底之上；所述谐振结构位于所述底部声反射层之上。A flexible substrate thin film bulk acoustic wave resonator, comprising: a flexible substrate, a bottom acoustic reflection layer, and a resonance structure, wherein: the bottom acoustic reflection layer is located on the flexible substrate; and the resonance structure is located on the flexible substrate. Said above the bottom acoustic reflection layer.
  2. 根据权利要求1所述的柔性基底薄膜体声波谐振器，其特征在于，所述底部声反射层包括：The flexible base film bulk acoustic wave resonator according to claim 1, wherein the bottom acoustic reflection layer comprises:
    单层低声阻抗层；或者，Single layer low acoustic impedance layer; or,
    N组布拉格反射结构，其中N为正整数，每组所述布拉格反射结构包括低声阻抗层和高声阻抗层。N groups of Bragg reflection structures, where N is a positive integer, and each group of Bragg reflection structures includes a low acoustic impedance layer and a high acoustic impedance layer.
  3. 根据权利要求2所述的柔性基底薄膜体声波谐振器，其特征在于，所述低声阻抗层包括：环氧基树脂、聚乙二烯、氧化硅、铝、碳掺杂氧化硅、纳米多孔甲基倍半硅氧烷、纳米多孔氢倍半硅氧烷、包含甲基倍半硅氧烷和氢硅倍半环氧乙烷的纳米多孔混合物、纳米玻璃、气凝胶、干凝胶、旋涂玻璃、聚对二甲苯或SiLK。The flexible substrate thin film bulk acoustic resonator according to claim 2, wherein the low acoustic impedance layer comprises: epoxy resin, polyethylene, silicon oxide, aluminum, carbon-doped silicon oxide, and nanoporous Methyl silsesquioxane, nanoporous hydrogen silsesquioxane, nanoporous mixture containing methyl silsesquioxane and hydrogen silsesquioxane, nanoglass, aerogel, xerogel, Spin-coated glass, parylene or SiLK.
  4. 根据权利要求2所述的柔性基底薄膜体声波谐振器，其特征在于，所述低声阻抗层的厚度小于1μm。The flexible substrate thin film bulk acoustic resonator according to claim 2, wherein the thickness of the low acoustic impedance layer is less than 1 μm.
  5. 根据权利要求2所述的柔性基底薄膜体声波谐振器，其特征在于，所述高声阻抗层包括：丁基合成橡胶、聚乙烯、氯丁橡胶、钨、钼、铂、钌、铱、钨钛、五氧化二钽、氧化哈、氧化铝、硅化络、碳化铌、氮化钽、碳化钛、氧化钛、碳化钒、氮化钨、氧化钨、碳化锆、类金刚石或硅掺杂的金刚石。The flexible base film bulk acoustic wave resonator according to claim 2, wherein the high acoustic impedance layer comprises: butyl synthetic rubber, polyethylene, neoprene, tungsten, molybdenum, platinum, ruthenium, iridium, tungsten Titanium, tantalum pentoxide, hafnium oxide, alumina, silicide, niobium carbide, tantalum nitride, titanium carbide, titanium oxide, vanadium carbide, tungsten nitride, tungsten oxide, zirconium carbide, diamond-like or silicon-doped diamond .
  6. 根据权利要求2所述的柔性基底薄膜体声波谐振器，其特征在于，所述高声阻抗层的厚度小于1μm。The flexible base film bulk acoustic wave resonator according to claim 2, wherein the thickness of the high acoustic impedance layer is less than 1 μm.
  7. 根据权利要求1所述的柔性基底薄膜体声波谐振器，其特征在于，所述谐振结构包括自下而上依次排列的：The flexible base film bulk acoustic wave resonator according to claim 1, wherein the resonance structure comprises:
    第一电极、第一压电层和第二电极；或者，A first electrode, a first piezoelectric layer, and a second electrode; or
    第一电极、第一压电层、第二电极、第二压电层、第三电极；或者，A first electrode, a first piezoelectric layer, a second electrode, a second piezoelectric layer, and a third electrode; or,
    第一电极、第一压电层、第二电极、解耦层、第三电极、第二压电层、第四电极。The first electrode, the first piezoelectric layer, the second electrode, the decoupling layer, the third electrode, the second piezoelectric layer, and the fourth electrode.
  8. 根据权利要求7所述的柔性基底薄膜体声波谐振器，其特征在于，所述第一压电层和/或所述第二压电层为复合压电层。The flexible base film bulk acoustic wave resonator according to claim 7, wherein the first piezoelectric layer and / or the second piezoelectric layer are composite piezoelectric layers.
  9. 根据权利要求1至8中任一项所述的柔性基底薄膜体声波谐振器，其特征在于，所述柔性基底的顶部表面具有微小空腔结构。The flexible substrate thin film bulk acoustic resonator according to any one of claims 1 to 8, wherein a top surface of the flexible substrate has a micro cavity structure.
  10. 根据权利要求9所述的柔性基底薄膜体声波谐振器，其特征在于，所述微小空腔的宽度为：30μm至500μm。The flexible base film bulk acoustic wave resonator according to claim 9, wherein the width of the micro cavity is: 30 μm to 500 μm.
  11. 根据权利要求9所述的柔性基底薄膜体声波谐振器，其特征在于，所述微小空腔的深度为：0.1μm至10μm。The flexible substrate thin film bulk acoustic resonator according to claim 9, wherein the depth of the micro cavity is: 0.1 μm to 10 μm.
  12. 根据权利要求9所述的柔性基底薄膜体声波谐振器，其特征在于，所述微小空腔结构为三棱锥空腔阵列结构、圆锥空腔阵列结构或三棱柱空腔阵列结构。The flexible substrate thin film bulk acoustic resonator according to claim 9, wherein the micro cavity structure is a triangular pyramid cavity array structure, a cone cavity array structure, or a triangular prism cavity array structure.
  13. 一种柔性基底薄膜体声波谐振器的形成方法，其特征在于，包括：A method for forming a flexible base film bulk acoustic wave resonator, comprising:
    提供牺牲层；Provide a sacrificial layer;
    在所述牺牲层之上形成底部声反射层；Forming a bottom acoustic reflection layer on the sacrificial layer;
    在所述底部声反射层之上形成谐振结构；Forming a resonance structure on the bottom acoustic reflection layer;
    去除所述牺牲层，从而得到堆叠结构，然后将所述堆叠结构转移 到柔性基底上，所述堆叠结构包括所述底部声反射层和所述谐振结构。The sacrificial layer is removed to obtain a stacked structure, and then the stacked structure is transferred to a flexible substrate. The stacked structure includes the bottom acoustic reflection layer and the resonance structure.
  14. 根据权利要求13所述的柔性基底薄膜体声波谐振器的形成方法，其特征在于，所述底部声反射层包括：The method for forming a flexible base film bulk acoustic wave resonator according to claim 13, wherein the bottom acoustic reflection layer comprises:
    单层低声阻抗层；或者，Single layer low acoustic impedance layer; or,
    N组布拉格反射结构，其中N为正整数，每组所述布拉格反射结构包括低声阻抗层和高声阻抗层。N groups of Bragg reflection structures, where N is a positive integer, and each group of Bragg reflection structures includes a low acoustic impedance layer and a high acoustic impedance layer.
  15. 根据权利要求14所述的柔性基底薄膜体声波谐振器的形成方法，其特征在于，所述低声阻抗层包括：环氧基树脂、聚乙二烯、氧化硅、铝、碳掺杂氧化硅、纳米多孔甲基倍半硅氧烷、纳米多孔氢倍半硅氧烷、包含甲基倍半硅氧烷和氢硅倍半环氧乙烷的纳米多孔混合物、纳米玻璃、气凝胶、干凝胶、旋涂玻璃、聚对二甲苯或SiLK。The method for forming a flexible substrate thin film bulk acoustic resonator according to claim 14, wherein the low acoustic impedance layer comprises: epoxy-based resin, polyethylene, silicon oxide, aluminum, and carbon-doped silicon oxide , Nanoporous methylsilsesquioxane, nanoporous hydrogen silsesquioxane, nanoporous mixture containing methylsilsesquioxane and hydrogen silsesquioxane, nanoglass, aerogel, dry Gel, spin-on glass, parylene or SiLK.
  16. 根据权利要求14所述的柔性基底薄膜体声波谐振器，其特征在于，所述低声阻抗层的厚度小于1μm。The flexible substrate thin film bulk acoustic resonator according to claim 14, wherein the thickness of the low acoustic impedance layer is less than 1 μm.
  17. 根据权利要求14所述的柔性基底薄膜体声波谐振器的形成方法，其特征在于，所述高声阻抗层包括：丁基合成橡胶、聚乙烯、氯丁橡胶、钨、钼、铂、钌、铱、钨钛、五氧化二钽、氧化哈、氧化铝、硅化络、碳化铌、氮化钽、碳化钛、氧化钛、碳化钒、氮化钨、氧化钨、碳化锆、类金刚石或硅掺杂的金刚石。The method for forming a flexible base film bulk acoustic resonator according to claim 14, wherein the high acoustic impedance layer comprises: butyl synthetic rubber, polyethylene, neoprene, tungsten, molybdenum, platinum, ruthenium, Iridium, titanium tungsten, tantalum pentoxide, hafnium oxide, alumina, silicide, niobium carbide, tantalum nitride, titanium carbide, titanium oxide, vanadium carbide, tungsten nitride, tungsten oxide, zirconium carbide, diamond-like or silicon doped Miscellaneous diamond.
  18. 根据权利要求14所述的柔性基底薄膜体声波谐振器，其特征在于，所述高声阻抗层的厚度小于1μm。The flexible base film bulk acoustic wave resonator according to claim 14, wherein the thickness of the high acoustic impedance layer is less than 1 μm.
  19. 根据权利要求13所述的柔性基底薄膜体声波谐振器的形成方法，其特征在于，所述谐振结构包括自下而上依次排列的：The method for forming a flexible base film bulk acoustic wave resonator according to claim 13, wherein the resonance structure comprises:
    第一电极、第一压电层和第二电极；或者，A first electrode, a first piezoelectric layer, and a second electrode; or
    第一电极、第一压电层、第二电极、第二压电层、第三电极；或 者，A first electrode, a first piezoelectric layer, a second electrode, a second piezoelectric layer, a third electrode; or
    第一电极、第一压电层、第二电极、解耦层、第三电极、第二压电层、第四电极。The first electrode, the first piezoelectric layer, the second electrode, the decoupling layer, the third electrode, the second piezoelectric layer, and the fourth electrode.
  20. 根据权利要求19所述的柔性基底薄膜体声波谐振器的形成方法，其特征在于，所述第一压电层和/或所述第二压电层为复合压电层。The method for forming a flexible base film bulk acoustic wave resonator according to claim 19, wherein the first piezoelectric layer and / or the second piezoelectric layer is a composite piezoelectric layer.
  21. 根据权利要求13至20中任一项所述的柔性基底薄膜体声波谐振器的形成方法，其特征在于，还包括：在所述柔性基底的顶部表面形成微小空腔结构。The method for forming a flexible base film bulk acoustic wave resonator according to any one of claims 13 to 20, further comprising: forming a micro cavity structure on a top surface of the flexible base.
  22. 根据权利要求21所述的柔性基底薄膜体声波谐振器的形成方法，其特征在于，所述微小空腔的宽度为：30μm至500μm。The method for forming a flexible base film bulk acoustic wave resonator according to claim 21, wherein the width of the micro cavity is: 30 μm to 500 μm.
  23. 根据权利要求21所述的柔性基底薄膜体声波谐振器的形成方法，其特征在于，所述微小空腔的深度为：0.1μm至10μm。The method for forming a flexible base film bulk acoustic wave resonator according to claim 21, wherein the depth of the micro cavity is: 0.1 μm to 10 μm.
  24. 根据权利要求21所述的柔性基底薄膜体声波谐振器的形成方法，其特征在于，所述微小空腔结构为三棱锥空腔阵列结构、圆锥空腔阵列结构或三棱柱空腔阵列结构。The method for forming a flexible substrate thin film bulk acoustic resonator according to claim 21, wherein the micro cavity structure is a triangular pyramid cavity array structure, a conical cavity array structure, or a triangular prism cavity array structure.
PCT/CN2018/112092 2018-09-30 2018-10-26 Flexible substrate film bulk acoustic resonator and forming method therefor WO2020062385A1 (en)

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