WO2020087566A1 - 一种混合声波谐振器及其制备方法 - Google Patents

一种混合声波谐振器及其制备方法 Download PDF

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Publication number
WO2020087566A1
WO2020087566A1 PCT/CN2018/115041 CN2018115041W WO2020087566A1 WO 2020087566 A1 WO2020087566 A1 WO 2020087566A1 CN 2018115041 W CN2018115041 W CN 2018115041W WO 2020087566 A1 WO2020087566 A1 WO 2020087566A1
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Prior art keywords
acoustic wave
bulk acoustic
piezoelectric film
resonator
substrate
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PCT/CN2018/115041
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English (en)
French (fr)
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李平
胡念楚
贾斌
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开元通信技术（厦门）有限公司
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Priority to US16/768,691 priority Critical patent/US10958236B2/en
Publication of WO2020087566A1 publication Critical patent/WO2020087566A1/zh

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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
    • H03H9/02015—Characteristics of piezoelectric layers, e.g. cutting angles
    • 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
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H03H9/02574—Characteristics of substrate, e.g. cutting angles of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
    • 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
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/08—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of resonators or networks using surface acoustic waves
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02007—Details of bulk acoustic wave devices
    • H03H9/02086—Means for compensation or elimination of undesirable effects
    • H03H9/02102—Means for compensation or elimination of undesirable effects of temperature influence
    • 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
    • H03H9/02228—Guided bulk acoustic wave devices or Lamb wave devices having interdigital transducers situated in parallel planes on either side of a piezoelectric layer
    • 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
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02818—Means for compensation or elimination of undesirable effects
    • H03H9/02834—Means for compensation or elimination of undesirable effects of temperature influence
    • 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
    • H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
    • 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
    • H03H9/172—Means for mounting on a substrate, i.e. means constituting the material interface confining the waves to a volume
    • H03H9/173—Air-gaps
    • 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
    • H03H9/205—Constructional features of resonators consisting of piezoelectric or electrostrictive material having multiple resonators
    • 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
    • H03H2003/021—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 air-gap type

Definitions

  • the invention relates to the technical field of resonators, in particular to a hybrid acoustic wave resonator and a preparation method of the hybrid acoustic wave resonator.
  • filters are mainly divided into surface acoustic wave filters and bulk acoustic wave filters.
  • surface acoustic waves are mainly used in the low frequency range of signal frequencies less than 2GHz
  • bulk acoustic wave devices are mainly used in the high frequency range of signal frequencies greater than 2GHz .
  • the resonator is the basic unit that constitutes the filter. Therefore, in order to reduce the area of the resonator, how to integrate different resonators on the same substrate. On the premise of meeting different needs, reducing the area of the filter is Problems urgently needed to be solved by those skilled in the art.
  • the present invention provides a hybrid acoustic wave resonator, including:
  • a piezoelectric film on the surface of the substrate is A piezoelectric film on the surface of the substrate
  • An interdigitated electrode located in the first region of the surface of the piezoelectric film facing away from the substrate;
  • At least two grooves located in the second region of the surface of the piezoelectric film facing away from the substrate; wherein a bulk acoustic wave propagation portion is formed between adjacent grooves, and the bulk acoustic wave propagation portion has opposite Two side surfaces;
  • Bulk acoustic wave electrodes respectively located on the side surface of the bulk acoustic wave propagation part; wherein the bulk acoustic wave electrode is provided with an air gap on the surface facing away from the bulk acoustic wave propagation part.
  • the piezoelectric film is a single crystal piezoelectric film.
  • the grooves are parallel to each other.
  • the width of the air gap is not less than 2 ⁇ m.
  • the resonator further includes:
  • a dielectric layer having a positive frequency temperature coefficient between the substrate and the piezoelectric film is provided.
  • the resonator further includes:
  • the invention also provides a method for preparing a hybrid acoustic wave resonator, including:
  • Bulk acoustic wave electrodes respectively located on the side surfaces of the bulk acoustic wave propagation portion are provided in the groove to make the hybrid acoustic wave resonator; wherein the bulk acoustic wave electrodes face away from the surface of the bulk acoustic wave propagation portion There is an air gap.
  • the arranging the bulk acoustic wave electrodes on the side surfaces of the bulk acoustic wave propagation part in the groove includes:
  • the conductive layer is patterned to form the air gap and the bulk acoustic wave electrode.
  • the method further includes:
  • a dielectric layer with a positive frequency temperature coefficient is provided on the surface of the substrate;
  • the disposing the piezoelectric film on the surface of the substrate includes:
  • the piezoelectric film is bonded to the surface of the dielectric layer.
  • the method further includes:
  • the etching at least two trenches in the second region on the surface of the piezoelectric film includes:
  • the interdigitated electrodes are provided, at least two of the trenches are etched in the second region on the surface of the piezoelectric film;
  • the method further includes:
  • a hybrid acoustic wave resonator provided by the present invention is provided with an interdigitated electrode in the first region of the surface of the piezoelectric film facing away from the substrate, which is composed of an interdigital transducer, so that the hybrid acoustic wave resonator includes an acoustic surface Wave resonator; at least two grooves are provided in the second area of the surface of the piezoelectric film facing away from the substrate, a bulk acoustic wave propagation portion is formed between adjacent grooves, and bulk acoustic wave electrodes are provided on the side surface of the bulk acoustic wave propagation portion An air gap is provided on the surface of the bulk acoustic wave electrode facing away from the bulk acoustic wave propagation section.
  • the above air gap, bulk acoustic wave electrode and bulk acoustic wave propagation part constitute a bulk acoustic wave resonator, so that the surface acoustic wave resonator and the bulk acoustic wave resonator are provided in the hybrid acoustic wave resonator at the same time, which realizes the integration of different types of resonators;
  • the sound waves transmitted in the bulk acoustic wave propagation section and the sound waves transmitted in the interdigital transducer are transmitted in the horizontal direction, thereby ensuring that both the surface acoustic wave resonator and the bulk acoustic wave resonator have good performance when the same substrate is used performance.
  • the invention also provides a method for preparing a hybrid acoustic wave resonator.
  • the prepared hybrid acoustic wave resonator also has the above-mentioned beneficial effects, which will not be repeated here.
  • FIG. 1 is a schematic structural plan view of a hybrid acoustic wave resonator provided by an embodiment of the present invention
  • Figure 2 is a cross-sectional view taken along line A-A in Figure 1;
  • FIG. 3 is a schematic structural diagram of a specific hybrid acoustic wave resonator provided by an embodiment of the present invention.
  • FIG. 4 is a cross-sectional view taken along line A-A in FIG. 3;
  • 5 to 9 are process flowcharts of a method for preparing a hybrid acoustic wave resonator provided by an embodiment of the present invention.
  • 10 to 16 are process flow diagrams of a specific method for preparing a hybrid acoustic wave resonator provided by an embodiment of the present invention.
  • the core of the present invention is to provide a hybrid acoustic wave resonator.
  • the acoustic wave in the surface acoustic wave resonator is generally transmitted in the horizontal direction of the surface of the piezoelectric film
  • the acoustic wave in the bulk acoustic wave device is generally transmitted in the vertical direction of the thickness of the piezoelectric film.
  • the direction of the crystal orientation of the substrate in the resonator is the same as the direction of acoustic wave transmission in the resonator.
  • the crystal orientation of the substrate is usually made in one direction, and the direction of the acoustic wave transmission between the surface acoustic wave resonator and the bulk acoustic wave resonator is different, so it is usually impossible to guarantee the performance of each resonator.
  • the hybrid acoustic wave resonator provided by the present invention is provided with an interdigitated electrode in the first area of the surface of the piezoelectric film facing away from the substrate to form an interdigital transducer, so that the hybrid acoustic wave resonator includes sound Surface wave resonator; at least two grooves are provided in the second area of the surface of the side of the piezoelectric film facing away from the substrate, a bulk acoustic wave propagation part is formed between adjacent grooves, and a bulk acoustic wave is provided on the side surface of the bulk acoustic wave propagation part
  • the electrode is provided with an air gap on the surface of the bulk acoustic wave electrode facing away from the bulk acoustic wave propagation portion.
  • the above air gap, bulk acoustic wave electrode and bulk acoustic wave propagation part constitute a bulk acoustic wave resonator, so that the surface acoustic wave resonator and the bulk acoustic wave resonator are provided in the hybrid acoustic wave resonator at the same time, which realizes the integration of different types of resonators;
  • the sound waves transmitted in the bulk acoustic wave propagation section and the sound waves transmitted in the interdigital transducer are transmitted in the horizontal direction, thereby ensuring that both the surface acoustic wave resonator and the bulk acoustic wave resonator have good performance when the same substrate is used performance.
  • FIG. 1 is a schematic top view of a hybrid acoustic wave resonator provided by an embodiment of the present invention.
  • FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1.
  • the hybrid acoustic resonator includes a substrate 1; a piezoelectric film 2 on the surface of the substrate 1; and a piezoelectric film 2 on the surface facing away from the substrate
  • the interdigitated electrode 3 in the first area on the side surface of the bottom 1; at least two grooves 4 located in the second area on the side surface of the piezoelectric film 2 facing away from the substrate 1;
  • a bulk acoustic wave propagation section 5 is formed between 4, the bulk acoustic wave propagation section 5 has two opposite side surfaces; a bulk acoustic wave electrode 6 located on a side surface of the bulk acoustic wave propagation section 5 respectively; wherein, the bulk acoustic wave electrode 6
  • An air gap 7 is provided on the surface facing away from the bulk acoustic wave propagation section 5.
  • the above substrate 1 mainly plays a supporting role, and the piezoelectric thin film 2 and other structures need to be arranged on the surface of the substrate 1 in a certain order.
  • the material of the above substrate 1 may be specifically silicon, sapphire, silicon carbide, glass, etc.
  • the above substrate 1 may also be made of a composite material or other materials. Parameters such as the specific material and thickness of the substrate 1 are not specifically limited in the embodiments of the present invention.
  • the piezoelectric film 2 is located on the surface of the substrate 1. Generally, the piezoelectric film 2 is located on only one surface of the substrate 1.
  • the so-called piezoelectric film 2 is a film made of piezoelectric material.
  • the piezoelectric film 2 can realize the mutual conversion between mechanical energy and electrical energy: when pressure is applied to the piezoelectric film 2, a voltage can be generated at both ends of the piezoelectric film 2, that is, a positive piezoelectric effect; 2 When a voltage is applied, the piezoelectric film 2 can produce a corresponding deformation, that is, the reverse piezoelectric effect.
  • the piezoelectric film 2 When a varying voltage, such as an alternating voltage, is applied to the piezoelectric film 2, the piezoelectric film 2 can vibrate, thereby generating acoustic waves in the piezoelectric film 2. It should be noted that, in the embodiment of the present invention, the above sound wave may propagate on the surface of the piezoelectric film 2 or may propagate in a certain direction inside the piezoelectric film 2.
  • the material of the piezoelectric film 2 may specifically be aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), lithium tantalate (LiTaO 3 ), niobate Lithium (LiNbO 3 ), the above-mentioned piezoelectric materials doped with rare earth elements, etc.
  • AlN aluminum nitride
  • ZnO zinc oxide
  • PZT lead zirconate titanate
  • LiTaO 3 lithium tantalate
  • LiNbO 3 niobate Lithium
  • the interdigital electrode 3 is located in the first region of the surface of the piezoelectric film 2 facing away from the substrate 1.
  • the piezoelectric film 2 and the interdigital electrode 3 located in the first area may constitute an interdigital transducer.
  • the function of the interdigital transducer is to realize acoustic-electrical transduction.
  • the shape of the interdigital electrode 3 is like the fingers of two hands intersecting.
  • the interdigital electrode 3 usually includes two parallel busbars and two busbars. An electrode that is electrically connected alternately with two bus bars.
  • the voltage applied to the interdigitated electrode 3 causes the piezoelectric film 2 to vibrate, thereby forming an acoustic wave propagating in the direction of the extension line of the generatrix on the surface of the piezoelectric film 2.
  • SAW surface acoustic wave
  • a plurality of surface acoustic wave resonators with the same frequency or different frequencies can be provided on the surface of the piezoelectric film 2, and only the width and spacing of the interdigital electrodes 3 need to be adjusted to form different frequencies.
  • the material of the interdigitated electrode 3 can be molybdenum (Mo), tungsten (W), chromium (Cr), titanium (Ti), aluminum (Al), copper (Cu), iridium (Ir), One of ruthenium (Ru), silicon (Si), graphene (Graphene), carbon nanotube (Carbon Nanotube), or a composite of multiple materials among the above materials.
  • Mo molybdenum
  • W tungsten
  • Cr chromium
  • Ti titanium
  • Al aluminum
  • Cu copper
  • Ir iridium
  • Ru ruthenium
  • Si silicon
  • Graphene graphene
  • Carbon Nanotube Carbon Nanotube
  • the depth of the groove 4 is usually the same as the thickness of the piezoelectric film 2, that is, the groove 4
  • the piezoelectric film 2 penetrates the piezoelectric film 2 in the thickness direction.
  • the plurality of grooves 4 provided in the second region on the surface of the piezoelectric film 2 are parallel to each other, that is, the axes of the plurality of grooves 4 are parallel to each other.
  • a bulk acoustic wave propagation portion 5 is formed between the above-mentioned adjacent grooves 4.
  • the acoustic wave of the bulk acoustic wave resonator will only propagate in the bulk acoustic wave propagation section 5 described above.
  • the above-mentioned bulk acoustic wave propagation section 5 has two side surfaces, and these two side surfaces are respectively two opposite inner side walls of the two grooves 4 forming the bulk acoustic wave propagation section 5.
  • the grooves 4 are provided with bulk acoustic wave electrodes 6 located on the surface of the bulk acoustic wave propagation section 5 side, and an air gap 7 is provided on the surface of the bulk acoustic wave electrode 6 facing away from the bulk acoustic wave propagation section 5.
  • the bulk acoustic wave propagation section 5 generally has two opposing side surfaces.
  • any individual acoustic wave propagation section 5 either side surface is usually provided with the bulk acoustic wave electrode 6, the two bulk acoustic wave electrodes 6 and the The bulk acoustic wave propagation part 5 between the two bulk acoustic wave electrodes 6 may constitute an integrated acoustic wave resonator, and a bulk acoustic wave (BAW) filter may be constituted by cooperating between the plurality of bulk acoustic wave resonators.
  • BAW bulk acoustic wave
  • the frequency of operation of the bulk acoustic wave resonator is related to the width of the bulk acoustic wave propagation portion 5, that is, the frequency of operation of the bulk acoustic wave resonator is related to the distance between the two adjacent trenches 4.
  • the distance between the two adjacent trenches 4 can be set according to actual conditions, and is not specifically limited in the embodiment of the present invention. It should be noted that, in the embodiment of the present invention, a plurality of bulk acoustic wave resonators with the same frequency or different frequencies may be provided in the piezoelectric film 2, and only need to adjust the spacing between adjacent grooves 4 to form different frequencies Bulk acoustic wave resonator.
  • the material of the bulk acoustic wave electrode 6 may be molybdenum (Mo), tungsten (W), chromium (Cr), aluminum (Al), copper (Cu), iridium (Ir), ruthenium (Ru), One of silicon (Si), graphene (Graphene), carbon nanotube (Carbon Nanotube), or a composite of multiple materials among the above materials.
  • Mo molybdenum
  • tungsten W
  • Cr chromium
  • Al aluminum
  • Cu copper
  • Ir iridium
  • Ru ruthenium
  • the specific material of the bulk acoustic wave electrode 6 is not specifically limited in your embodiment of the present invention, depending on the specific situation.
  • the function of the air gap 7 is to limit the sound waves emitted by the bulk acoustic wave electrode 6 to propagate in the bulk acoustic wave propagation unit 5. Since the acoustic impedance of air is close to zero, it can form a total reflection of the sound wave energy. By setting the above-mentioned air gap 7, it is possible to effectively prevent the sound wave energy from propagating laterally along the substrate 1, thereby effectively reducing the stray mode in the bulk acoustic wave resonator, so that the bulk acoustic wave resonator can have a high quality factor.
  • the width of the air gap 7 needs to be not less than 2 ⁇ m. In order to limit the size of the hybrid acoustic wave resonator provided in the embodiments of the present invention, the width of the air gap 7 is generally not greater than 30 ⁇ m.
  • more than one bulk acoustic wave electrode 6 may be provided in any of the grooves 4 described above.
  • two bulk acoustic wave propagation parts 5 may be formed between the three mutually parallel grooves 4, wherein the two inner side walls of the groove 4 in the middle are respectively two different bodies
  • the side surface of the acoustic wave propagation part 5 is provided with the bulk acoustic wave electrode 6 on both inner side walls of the groove 4 in the middle, and a total of two bulk acoustic wave electrodes 6 are provided in the groove 4.
  • the air gap 7 needs to be provided between the two bulk acoustic wave electrodes 6 located in the same groove 4.
  • a hybrid acoustic wave resonator provided in an embodiment of the present invention is provided with an interdigital electrode 3 in a first region of the surface of the piezoelectric film 2 facing away from the substrate 1 to form an interdigital transducer, thereby resonating the hybrid acoustic wave
  • a surface acoustic wave resonator is included in the device; at least two grooves 4 are provided in the second area of the surface of the piezoelectric film 2 facing away from the substrate 1, and a bulk acoustic wave propagation portion 5 is formed between adjacent grooves 4 in the body
  • a bulk acoustic wave electrode 6 is provided on the side surface of the acoustic wave propagation section 5, and an air gap 7 is provided on the surface of the bulk acoustic wave electrode 6 facing away from the bulk acoustic wave propagation section 5.
  • the above-mentioned air gap 7, bulk acoustic wave electrode 6 and bulk acoustic wave propagation part 5 constitute a bulk acoustic wave resonator, so that a surface acoustic wave resonator and a bulk acoustic wave resonator are simultaneously provided in the hybrid acoustic wave resonator, and the integration of different types of resonators is realized ;
  • the sound waves transmitted in the bulk acoustic wave propagation section 5 and the sound waves transmitted in the interdigital transducer are transmitted in the horizontal direction, so that the surface acoustic wave resonator and the bulk acoustic wave resonance can be ensured when the same substrate 1 is used
  • the devices have good performance.
  • FIG. 3 is a schematic structural diagram of a specific hybrid acoustic wave resonator provided by an embodiment of the present invention
  • FIG. 4 is a cross-sectional view taken along line A-A in FIG. 3.
  • the embodiments of the invention further specifically limit the structure of the hybrid acoustic wave resonator on the basis of the above-mentioned embodiments of the invention.
  • the rest of the content has been described in detail in the above embodiments of the invention and will not be repeated here.
  • the piezoelectric film 2 in the hybrid acoustic wave resonator may be a single crystal piezoelectric film 2.
  • the direction of the stronger coupling coefficient is a horizontal direction parallel to the surface of the substrate 1, and the horizontal direction is also provided by the embodiment of the present invention.
  • the propagation direction of the acoustic wave in the bulk acoustic wave resonator and the propagation direction of the acoustic wave in the surface acoustic wave resonator are both directions in which the coupling coefficient of the single crystal piezoelectric film 2 is large, so that the lateral coupling coefficient of the single crystal piezoelectric film 2
  • the resonator may further include a dielectric layer 8 having a positive frequency temperature coefficient between the substrate 1 and the piezoelectric film 2.
  • TCF positive frequency temperature coefficient
  • the materials of each structure in the hybrid acoustic wave resonator provided by the embodiments of the present invention are generally materials with negative frequency temperature coefficients.
  • the natural frequency of the materials used in the resonator at this stage will generally decrease as the ambient temperature increases, thereby affecting the temperature stability of the hybrid acoustic wave resonator.
  • the dielectric layer 8 with a positive frequency temperature coefficient between the substrate 1 and the piezoelectric film 2 can effectively improve the temperature coefficient of the resonator, so that the natural frequency of the resonator will not be too obvious with the change of the ambient temperature Fluctuation, so that the resonator has good temperature stability.
  • the material of the dielectric layer 8 may specifically be silicon oxide (SiO 2 ), silicon oxide doped with fluorine (F), silicon oxide doped with boron (B), etc.
  • the specific material is not specifically limited in the embodiment of the present invention.
  • the resonator may further include a plurality of first pads 91 and a plurality of second pads 92 on the surface of the piezoelectric film 2 facing away from the substrate 1;
  • the first pad 91 is electrically connected to the bus bar in the interdigital electrode 3;
  • the second pad 92 is electrically connected to the bulk acoustic wave electrode 6.
  • the first pad 91 is usually a connection point of the surface acoustic wave resonator and other components in the hybrid acoustic wave resonator provided by the embodiment of the present invention
  • the second pad 92 is usually a connection point of the bulk acoustic wave device and other components.
  • the first pad 91 and the second pad 92 are usually provided on the surface of the piezoelectric film 2 facing away from the substrate 1, wherein the first pad 91 usually needs to correspond one-to-one with the bus bar in the interdigitated electrode 3.
  • the first pad 91 usually needs to be in contact with the corresponding bus bar to be electrically connected to the interdigital electrode 3; the second pad 92 usually needs to correspond one-to-one with the bulk acoustic wave electrode 6, and the second pad 92 usually needs to correspond to the corresponding
  • the bulk acoustic wave electrodes 6 are in contact with each other to be electrically connected to the bulk acoustic wave electrode 6.
  • the materials of the first pad 91 and the second pad 92 may specifically be chromium (Cr), nickel (Ni), tungsten (W), titanium tungsten (TiW), aluminum ( Al), copper (Cu), gold (Au), or a composite of multiple materials among the above materials.
  • the specific materials of the first pad 91 and the second pad 92 are not specifically limited in the embodiment of the present invention, and depend on the specific situation.
  • reflection grids are provided on both sides of the interdigitated electrode 3 along the direction of the extension line of the generatrix.
  • the reflection grid is used to reflect the acoustic wave, and the acoustic wave in the surface acoustic wave resonator can be limited to the interdigital transducer through the reflective grid, thereby avoiding the loss of the acoustic wave energy from both sides of the interdigital transducer.
  • the hybrid acoustic wave resonator provided by the embodiment of the present invention can ensure that both the bulk acoustic wave resonator and the surface acoustic wave resonator have a high quality factor by using the single crystal piezoelectric film 2; by setting the temperature to have a positive frequency
  • the dielectric layer 8 of the coefficient can prevent the natural frequency of the resonator from fluctuating too much with changes in the ambient temperature; by providing the first pad 91 and the second pad 92, the hybrid acoustic wave device and other components can be electrically connected to each other .
  • the preparation method of the hybrid acoustic wave resonator provided by the present invention will be described below.
  • the preparation method described below and the structure of the hybrid acoustic wave resonator described above may correspond to each other.
  • FIG. 5 to FIG. 9 are process flow diagrams of a method for manufacturing a hybrid acoustic wave resonator provided by an embodiment of the present invention.
  • the method for preparing the hybrid acoustic wave resonator includes:
  • the pre-prepared piezoelectric film 2 is usually bonded to the surface of the pre-prepared substrate 1.
  • the specific bonding method reference may be made to the prior art, which is not specifically limited in the embodiments of the present invention.
  • the surface of the piezoelectric film 2 is generally divided into a first area and a second area.
  • the piezoelectric thin film 2 is usually ground and polished so that the piezoelectric thin film 2 reaches a predetermined thickness, which is usually determined by the maximum area of a single bulk acoustic wave resonator constituting a bulk acoustic wave (BAW) filter Decide, for example, if the maximum area of the bulk acoustic wave resonator is S, the remaining thickness of the piezoelectric film 2 after grinding and polishing needs to be greater than or equal to
  • BAW bulk acoustic wave
  • the surface of the piezoelectric film 2 to be bonded can be implanted with particles before bonding to A modified layer is formed at the thickness; when the piezoelectric film 2 is bonded again, low-temperature annealing may be performed to separate the piezoelectric film 2 from the modified layer, thereby leaving the piezoelectric film 2 with a predetermined thickness.
  • the piezoelectric film 2 with a predetermined thickness is fixedly connected to the substrate 1, so as to realize the thinning process of the piezoelectric film 2.
  • S102 providing an interdigitated electrode in the first region on the surface of the piezoelectric film.
  • the interdigital electrode 3 needs to be provided in the first area on the surface of the piezoelectric film 2 to form an interdigital transducer, and the above-mentioned interdigital transducer can constitute the most basic surface acoustic wave Resonator.
  • the specific structure of the interdigital transducer has been described in detail in the above embodiments of the invention, and will not be repeated here.
  • the interdigital electrode 3 may be provided in the first region on the surface of the piezoelectric film 2 by various methods, for example: in the first type, a conductive layer may be sputtered on the surface of the piezoelectric film 2; The conductive layer is etched to pattern the conductive layer, thereby forming the interdigital electrode 3 in the first region on the surface of the piezoelectric film 2.
  • a glue layer can be provided on the surface of the piezoelectric film 2; secondly, the glue layer is etched to expose the area where the interdigital electrode 3 needs to be provided on the surface of the piezoelectric film 2; again, sputtering is performed on the surface of the glue layer A conductive layer, which will also cover the exposed areas of the piezoelectric film 2 where the interdigital electrode 3 is to be placed; Finally, peel off the above-mentioned adhesive layer, at this time the conductive layer covering the surface of the adhesive layer will be synchronously peeled off To form the interdigital electrode 3 in the first region on the surface of the piezoelectric film 2.
  • S103 Etching at least two trenches in the second region on the surface of the piezoelectric film.
  • a bulk acoustic wave propagation part 5 is formed between adjacent grooves 4, and the bulk acoustic wave propagation part 5 has two opposite side surfaces.
  • the second region on the surface of the piezoelectric film 2 is etched to form the trench 4 described above.
  • the specific structure of the trench 4 has been described in detail in the above embodiments of the invention, and will not be repeated here.
  • the piezoelectric film 2 is usually etched through. For the specific etching process, reference may be made to the prior art, which will not be repeated here.
  • the working frequency of the bulk acoustic wave resonator in the embodiment of the present invention is related to the thickness of the bulk acoustic wave propagation portion 5, that is, to the distance between the adjacent trenches 4, the spacing between the trenches 4 in this step
  • the choice needs to be determined according to the design of different applications, and is not specifically limited in the embodiments of the present invention.
  • S104 Bulk acoustic wave electrodes respectively located on the side surfaces of the bulk acoustic wave propagation part are arranged in the groove to make a hybrid acoustic wave resonator.
  • an air gap 7 is provided on the surface of the bulk acoustic wave electrode 6 facing away from the bulk acoustic wave propagation section 5.
  • a bulk acoustic wave electrode 6 located on the side surface of the bulk acoustic wave propagation section 5 is formed in the groove 4, and the bulk acoustic wave electrode 6 is usually required on both side surfaces of each bulk acoustic wave propagation section 5.
  • an air gap 7 for restricting the propagation of acoustic waves is generally required to finally make the hybrid acoustic wave resonator provided by the embodiment of the present invention.
  • S102 is a step mainly forming a surface acoustic wave resonator
  • S103 and S104 are steps mainly forming a bulk acoustic wave resonator
  • the interdigital electrode 3 may be formed on the surface of the piezoelectric film 2 to form a surface acoustic wave resonator, and then the bulk acoustic wave electrode 6 is provided in the piezoelectric film 2 to form a bulk acoustic wave resonator;
  • bulk acoustic wave electrodes 6 are provided in the piezoelectric thin film 2 to constitute a bulk acoustic wave resonator, and then interdigital electrodes 3 are formed on the surface of the piezoelectric thin film 2 to constitute a surface acoustic wave resonator.
  • the specific order can be set according to the actual
  • a method for manufacturing a hybrid acoustic wave resonator provided by an embodiment of the present invention, the prepared hybrid acoustic wave resonator is provided with an interdigitated electrode 3 in a first area of the surface of the side of the piezoelectric film 2 facing away from the substrate 1, Interdigital transducers are constructed so that the hybrid acoustic wave resonator includes a surface acoustic wave resonator; at least two grooves 4 are provided in the second area of the surface of the piezoelectric film 2 facing away from the substrate 1, adjacent grooves A bulk acoustic wave propagation section 5 is formed between the grooves 4, a bulk acoustic wave electrode 6 is provided on the surface of the bulk acoustic wave propagation section 5 side, and an air gap 7 is provided on the surface of the bulk acoustic wave electrode 6 facing away from the bulk acoustic wave propagation section 5.
  • the above-mentioned air gap 7, bulk acoustic wave electrode 6 and bulk acoustic wave propagation part 5 constitute a bulk acoustic wave resonator, so that a surface acoustic wave resonator and a bulk acoustic wave resonator are simultaneously provided in the hybrid acoustic wave resonator, and the integration of different types of resonators is realized ;
  • the sound waves transmitted in the bulk acoustic wave propagation section 5 and the sound waves transmitted in the interdigital transducer are transmitted in the horizontal direction, so that the surface acoustic wave resonator and the bulk acoustic wave resonance can be ensured when the same substrate 1 is used
  • the devices have good performance.
  • FIG. 10 to FIG. 16 are process flow diagrams of a specific method for manufacturing a hybrid acoustic wave resonator provided by an embodiment of the present invention.
  • the manufacturing method of the hybrid acoustic wave resonator includes:
  • a dielectric layer having a positive frequency temperature coefficient is provided on the surface of the substrate.
  • a dielectric layer 8 having a positive frequency temperature coefficient is usually deposited on the surface of the substrate 1 by a thin film deposition process. By depositing the dielectric layer 8 on the surface of the substrate 1 first, it is also convenient for the subsequent bonding of the piezoelectric film 2.
  • the piezoelectric film 2 is specifically bonded to the surface of the dielectric layer 8 so that the piezoelectric film 2 is fixedly connected to the substrate 1.
  • the rest of this step is basically the same as S101 in the above-mentioned embodiment of the invention.
  • S101 in the above-mentioned embodiment of the invention.
  • S203 providing an interdigitated electrode in the first region on the surface of the piezoelectric film.
  • this step is basically the same as S102 in the above-mentioned embodiment of the invention, and the detailed content has been described in detail in the above-mentioned embodiment of the invention, which will not be repeated here.
  • S204 Provide a protective layer covering the interdigitated electrode in the first area on the surface of the piezoelectric film.
  • the surface of the interdigital electrode 3 that has been set is covered with a protective layer to prevent the morphology of the interdigital electrode 3 during subsequent preparation of the bulk acoustic wave resonator Influence, thereby affecting the performance of surface acoustic wave devices.
  • the protective layer may be photoresist, etc.
  • interdigital electrodes 3 are first formed on the surface of the piezoelectric film 2 to form a surface acoustic wave resonator, and then bulk acoustic wave electrodes 6 are provided in the piezoelectric film 2 to form a bulk acoustic wave resonance Device. If the groove 4 and the bulk acoustic wave electrode 6 are provided first, the surface of the piezoelectric film 2 is no longer flat.
  • the surface of the piezoelectric film 2 is preferably a flat surface.
  • interdigital electrodes 3 are generally formed on the surface of the piezoelectric film 2 to form a surface acoustic wave resonator, and then bulk acoustic wave electrodes 6 are provided in the piezoelectric film 2 to form a bulk acoustic wave resonator.
  • S206 Provide a conductive layer in the trench.
  • an atomic layer deposition (ALD) process, an electroplating process, or a sputtering process with better shape retention can be used to deposit a conductive layer 61 in the trench, which can be filled
  • ALD atomic layer deposition
  • electroplating process electroplating
  • sputtering process with better shape retention can be used to deposit a conductive layer 61 in the trench, which can be filled
  • the entire trench 4 may only cover the bottom and side walls of the trench 4.
  • S207 pattern the conductive layer to form an air gap and bulk acoustic wave electrodes.
  • a stripping process or an etching process may be used to pattern the above-mentioned conductive layer 61 provided in the trench 4 to produce the air gap 7 described in the above embodiment of the invention.
  • the above-mentioned conductive layer 61 is made as a bulk acoustic wave electrode 6.
  • specific patterning process reference may be made to the prior art, which will not be repeated here.
  • the protective layer provided in S204 is removed, and the interdigital electrode 3 is exposed.
  • a protective layer is not provided on the surface of the interdigitated electrode 3 before S208, or if the above protective layer does not need to be removed, a protective layer that can play a role in temperature compensation, such as a silicon dioxide layer, etc., there is no need to perform This step.
  • first pad 91 and the second pad 92 described in the above embodiments of the invention may be further provided on the surface of the piezoelectric film 2.
  • first pad 91 and the second pad 92 described in the above embodiments of the invention may be further provided on the surface of the piezoelectric film 2.
  • a method for preparing a hybrid acoustic wave resonator provided by an embodiment of the present invention, by providing a dielectric layer 8 having a positive frequency temperature coefficient, the natural frequency of the resonator will not fluctuate too much with changes in ambient temperature;
  • the provision of the above-mentioned protective layer can effectively protect the interdigitated electrode 3 from being easily damaged in the subsequent steps; by providing the interdigitated electrode 3 first and then the bulk acoustic wave electrode 6, the interdigitated electrode 3 can be effectively ensured to have a good morphology.
  • RAM random access memory
  • ROM read-only memory
  • electrically programmable ROM electrically erasable and programmable ROM
  • registers hard disks, removable disks, CD-ROMs, or all fields of technology. Any other known storage medium.

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  • Acoustics & Sound (AREA)
  • Engineering & Computer Science (AREA)
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  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Abstract

一种混合声波谐振器，在压电薄膜（2）表面第一区域设置有叉指电极（3），从而使得混合声波谐振器中包括有声表面波谐振器；在压电薄膜（2）表面第二区域设置有至少两个沟槽（4），相邻沟槽（4）之间形成体声波传播部（5），在体声波传播部（5）侧表面设置有体声波电极（6），在体声波电极（6）背向体声波传播部（5）一侧表面设置有空气间隙（7），从而构成了体声波谐振器，使得混合声波谐振器中同时设置有声表面波谐振器和体声波谐振器，实现了不同种类谐振器的集成；同时在体声波传播部（5）中传递的声波以及在叉指换能器中传递的声波均是沿水平方向传递，保证了混合声波谐振器具有良好的性能。还涉及一种混合声波谐振器的制备方法，所制备而成的混合声波谐振器同样具有上述有益效果。

Description

一种混合声波谐振器及其制备方法
本申请要求于2018年10月30日提交中国专利局、申请号为201811277386.5、发明名称为“一种混合声波谐振器及其制备方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及谐振器技术领域，特别是涉及一种混合声波谐振器以及一种混合声波谐振器的制备方法。
背景技术
随着近年来科技不断的进步以及通讯行业的发展，移动终端，例如手机越来越普及。而滤波器作为移动终端中不可缺少的射频器件，也广泛的应用在移动终端中。
随着移动通信技术的发展，数据传输速率越来越快，频谱越来越拥挤，此时要求有更多的频带可以供移动通信使用。通信频带的增加，意味着移动终端特别是智能手机中，需要更多的滤波器来保证各个频带之间互不干扰。目前，支持4G通信的旗舰智能手机中，滤波器的数量已超过50个，在不久的将来这一数量还会成倍的增加。滤波器的数量在不断增加，而智能手机中各器件的布图面积不会大幅度增加，因此，要求滤波器必须在保证高性能的前提下进一步实现小型化、模块化。
在现阶段，滤波器主要分为声表面波滤波器以及体声波滤波器，其中声表面波主要应用在信号频率小于2GHz的低频范围，而体声波器件主要应用于信号频率大于2GHz的高频范围。随着智能手机中滤波器数量的不断增加，需要进一步缩小滤波器的尺寸。谐振器是构成滤波器的基本单元，因此，为了减小谐振器的面积，如何将不同的谐振器集成在同一衬底上，在能够在满足不同需求的前提下，减小滤波器的面积是本领域技术人员急需解决的问题。
发明内容
本发明的目的是提供一种混合声波谐振器，在同一衬底中集成有多种不同的谐振器结构；本发明的另一目的在于提供一种混合声波谐振器的制备方法，所制备而成的混合声波谐振器在同一衬底中集成有多种不同的谐振器结构。
为解决上述技术问题，本发明提供一种混合声波谐振器，包括：
衬底；
位于所述衬底表面的压电薄膜；
位于所述压电薄膜背向所述衬底一侧表面第一区域的叉指电极；
位于所述压电薄膜背向所述衬底一侧表面第二区域的至少两个沟槽；其中，相邻所述沟槽之间形成体声波传播部，所述体声波传播部具有相对的两个侧表面；
分别位于所述体声波传播部侧表面的体声波电极；其中，所述体声波电极背向所述体声波传播部一侧表面设置有空气间隙。
可选的，所述压电薄膜为单晶压电薄膜。
可选的，所述沟槽相互平行。
可选的，所述空气间隙的宽度不小于2μm。
可选的，所述谐振器还包括：
位于所述衬底与所述压电薄膜之间的具有正频率温度系数的介质层。
可选的，所述谐振器还包括：
位于所述压电薄膜背向所述衬底一侧表面的多个第一焊盘和多个第二焊盘；所述第一焊盘与所述叉指电极中的母线电连接；所述第二焊盘与所述体声波电极电连接。
本发明还提供了一种混合声波谐振器的制备方法，包括：
在衬底的表面设置压电薄膜；
在所述压电薄膜表面的第一区域设置叉指电极；
在所述压电薄膜表面的第二区域刻蚀至少两个沟槽；其中，相邻所述沟槽之间形成体声波传播部，所述体声波传播部具有相对的两个侧表面；
在所述沟槽内设置分别位于所述体声波传播部侧表面的体声波电极，以制成所述混合声波谐振器；其中，所述体声波电极背向所述体声波传播 部一侧表面设置有空气间隙。
可选的，所述在所述沟槽内设置分别位于所述体声波传播部侧表面的体声波电极包括：
在所述沟槽内设置导电层；
图形化所述导电层，以形成所述空气间隙和所述体声波电极。
可选的，在所述在衬底的表面设置压电薄膜之前，所述方法还包括：
在衬底的表面设置具有正频率温度系数的介质层；
所述在衬底的表面设置压电薄膜包括：
在所述介质层表面键合所述压电薄膜。
可选的，在所述压电薄膜表面的第一区域设置叉指电极之后，所述方法还包括：
在所述压电薄膜表面的第一区域设置覆盖所述叉指电极的保护层；
所述在所述压电薄膜表面的第二区域刻蚀至少两个沟槽包括：
在设置完所述叉指电极之后，在所述压电薄膜表面的第二区域刻蚀至少两个所述沟槽；
在所述沟槽内设置分别位于所述体声波传播部侧表面的体声波电极之后，所述方法还包括：
去除所述保护层。
本发明所提供的一种混合声波谐振器，在压电薄膜背向衬底一侧表面第一区域设置有叉指电极，构成有叉指换能器，从而使得混合声波谐振器中包括有声表面波谐振器；在压电薄膜背向衬底一侧表面第二区域设置有至少两个沟槽，相邻沟槽之间形成体声波传播部，在体声波传播部侧表面设置有体声波电极，在体声波电极背向体声波传播部一侧表面设置有空气间隙。上述空气间隙、体声波电极以及体声波传播部构成了体声波谐振器，从而使得混合声波谐振器中同时设置有声表面波谐振器和体声波谐振器，实现了不同种类谐振器的集成；同时在体声波传播部中传递的声波以及在叉指换能器中传递的声波均是沿水平方向传递，从而可以保证在使用同一种衬底时声表面波谐振器和体声波谐振器均具有良好的性能。
本发明还提供了一种混合声波谐振器的制备方法，所制备而成的混合 声波谐振器同样具有上述有益效果，在此不再进行赘述。
附图说明
为了更清楚的说明本发明实施例或现有技术的技术方案，下面将对实施例或现有技术描述中所需要使用的附图作简单的介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本发明实施例所提供的一种混合声波谐振器的俯视结构示意图；
图2为图1中沿A-A线的剖视图；
图3为本发明实施例所提供的一种具体的混合声波谐振器的结构示意图；
图4为图3中沿A-A线的剖视图；
图5至图9为本发明实施例所提供的一种混合声波谐振器制备方法的工艺流程图；
图10至图16为本发明实施例所提供的一种具体的混合声波谐振器制备方法的工艺流程图。
图中：1.衬底、2.压电薄膜、3.叉指电极、4.沟槽、5.体声波传播部、6.体声波电极、61.导电层、7.空气间隙、8.介质层、91.第一焊盘、92.第二焊盘。
具体实施方式
本发明的核心是提供一种混合声波谐振器。在现有技术中，由于声表面波谐振器中声波通常是沿压电薄膜表面的水平方向传递，而体声波器件中声波通常是沿压电薄膜厚度的垂直方向传递。为了使得谐振器的性能达到预设的要求，通常需要谐振器中衬底晶向的方向与该谐振器中声波传递方向相同。但是衬底的晶向通常制成朝一个方向，而声表面波谐振器与体声波谐振器之间声波传递的方向不同，所以通常无法在保证各个谐振器性 能的前提下将声表面波谐振器与体声波谐振器集成在同一衬底中。
而本发明所提供的一种混合声波谐振器，在压电薄膜背向衬底一侧表面第一区域设置有叉指电极，构成有叉指换能器，从而使得混合声波谐振器中包括有声表面波谐振器；在压电薄膜背向衬底一侧表面第二区域设置有至少两个沟槽，相邻沟槽之间形成体声波传播部，在体声波传播部侧表面设置有体声波电极，在体声波电极背向体声波传播部一侧表面设置有空气间隙。上述空气间隙、体声波电极以及体声波传播部构成了体声波谐振器，从而使得混合声波谐振器中同时设置有声表面波谐振器和体声波谐振器，实现了不同种类谐振器的集成；同时在体声波传播部中传递的声波以及在叉指换能器中传递的声波均是沿水平方向传递，从而可以保证在使用同一种衬底时声表面波谐振器和体声波谐振器均具有良好的性能。
为了使本技术领域的人员更好地理解本发明方案，下面结合附图和具体实施方式对本发明作进一步的详细说明。显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。
请参考图1以及图2，图1为本发明实施例所提供的一种混合声波谐振器的俯视结构示意图；图2为图1中沿A-A线的剖视图。
参见图1以及图2，在本发明实施例中，所述混合声波谐振器包括衬底1；位于所述衬底1表面的压电薄膜2；位于所述压电薄膜2背向所述衬底1一侧表面第一区域的叉指电极3；位于所述压电薄膜2背向所述衬底1一侧表面第二区域的至少两个沟槽4；其中，相邻所述沟槽4之间形成体声波传播部5，所述体声波传播部5具有相对的两个侧表面；分别位于所述体声波传播部5侧表面的体声波电极6；其中，所述体声波电极6背向所述体声波传播部5一侧表面设置有空气间隙7。
上述衬底1主要起支撑作用，上述压电薄膜2等结构均需要在衬底1的表面按照一定的顺序先后设置。在本发明实施例中，上述衬底1的材质可以具体为硅、蓝宝石、碳化硅、玻璃等等，当然上述衬底1也可以由复 合材料制备而成，或者是由其他材料制备而成。有关衬底1的具体材质以及厚度等参数在本发明实施例中并不做具体限定。
上述压电薄膜2位于衬底1的表面，通常情况下，上述压电薄膜2仅仅位于衬底1的一个表面。所谓压电薄膜2，即由压电材料所制成的薄膜。压电薄膜2可以实现机械能与电能之间的相互转换：当对压电薄膜2施加压力时，可以在压电薄膜2的两端产生电压，即正压电效应；相应的当对压电薄膜2施加电压时，压电薄膜2可以产生相应的形变，即逆压电效应。当对压电薄膜2施加变化的电压，例如交流电压时，可以使得压电薄膜2发生振动，从而在压电薄膜2中产生声波。需要说明的是，在本发明实施例中上述声波可以在压电薄膜2表面传播，也可以在压电薄膜2内部沿一定方向传播。
具体的，在本发明实施例中，压电薄膜2的材料可以具体为氮化铝(AlN)、氧化锌(ZnO)、锆钛酸铅(PZT)、钽酸锂(LiTaO 3)、铌酸锂(LiNbO 3)，掺杂稀土元素的上述压电材料等等，有关压电薄膜2的具体材质将在下述发明实施例中做详细介绍，在此不再进行展开描述。
上述叉指电极3位于压电薄膜2背向衬底1一侧表面的第一区域。位于第一区域的压电薄膜2以及叉指电极3可以构成一叉指换能器。叉指换能器的作用是实现声-电换能，上述叉指电极3的形状像两只手的手指交叉状，叉指电极3通常包括有两条相互平行的母线，以及位于两条母线之间与两条母线交替电连接的电极。在工作状态下，施加在叉指电极3中的电压会引起压电薄膜2振动，从而在压电薄膜2表面形成沿上述母线延长线方向传播的声波。有关上述叉指换能器的工作原理以及具体结构可以参考现有技术，在此不再进行赘述。通过上述叉指换能器即可构成最基本的声表面波(SAW)谐振器，通过多个上述叉指换能器之间相互配合即可构成声表面波滤波器。需要说明的是，在本发明实施例中可以在压电薄膜2表面设置多个频率相同或不同的声表面波谐振器，并且只需要调整叉指电极3的宽度以及间距即可形成不同频率的声表面波谐振器。
上述叉指电极3的材质在本发明实施例中可以为钼(Mo)、钨(W)、铬(Cr)、钛(Ti)、铝(Al)、铜(Cu)、铱(Ir)、钌(Ru)、硅(Si)、石 墨烯(Graphene)、碳纳米管(Carbon Nanotube)中的一种，或者是由上述材质中多种材质复合而成。当然，有关叉指电极3的具体材质在本发明你实施例中并不做具体限定，视具体情况而定。
在本发明实施例中，在压电薄膜2背向衬底1一侧表面的第二区域设置有至少两个沟槽4。为了制作的方便以及在相邻沟槽4之间形成的体声波谐振器中传递的声波不易扩散，上述沟槽4的深度通常与上述压电薄膜2的厚度相同，即所述沟槽4沿所述压电薄膜2厚度方向贯穿所述压电薄膜2。通常情况下，在本发明实施例中设置在压电薄膜2表面第二区域的多个沟槽4相互平行，即多个沟槽4的轴线相互平行。
上述相邻的沟槽4之间形成有体声波传播部5。顾名思义，在工作状态时，在本发明实施例所提供的混合声波谐振器中体声波谐振器的声波仅仅会在上述体声波传播部5进行传播。需要说明的是，上述体声波传播部5具有两个侧表面，这两个侧表面分别为形成体声波传播部5的两个沟槽4中两个相对的内侧壁。
在上述沟槽4中设置有分别位于上述体声波传播部5侧表面的体声波电极6，同时在体声波电极6背向体声波传播部5一侧表面设置有空气间隙7。上述体声波传播部5通常具有两个相对的侧表面，对于任一个体声波传播部5来说，任一侧表面通常均会设置有上述体声波电极6，两个上述体声波电极6以及位于两个体声波电极6之间的体声波传播部5可以构成一体声波谐振器，通过多个上述体声波谐振器之间相互配合即可构成体声波(BAW)滤波器。在本发明实施例中，体声波谐振器工作的频率与上述体声波传播部5的宽度有关，即体声波谐振器工作的频率与上述相邻两沟槽4之间的距离有关。有关上述相邻两沟槽4之间的距离可以根据实际情况自行设置，在本发明实施例中并不做具体限定。需要说明的是，在本发明实施例中可以在压电薄膜2中设置多个频率相同或不同的体声波谐振器，并且只需要调整相邻沟槽4之间的间距即可形成不同频率的体声波谐振器。
上述体声波电极6的材质在本发明实施例中可以为钼(Mo)、钨(W)、铬(Cr)、铝(Al)、铜(Cu)、铱(Ir)、钌(Ru)、硅(Si)、石墨烯(Graphene)、 碳纳米管(Carbon Nanotube)中的一种，或者是由上述材质中多种材质复合而成。当然，有关体声波电极6的具体材质在本发明你实施例中并不做具体限定，视具体情况而定。
上述空气间隙7的作用是为了将由体声波电极6所发出的声波限制在体声波传播部5中传播。由于空气的声阻抗接近于0，可以对声波能量形成全反射。通过设置上述空气间隙7可以有效避免声波能量沿着衬底1横向肆意传播，从而可以有效减少体声波谐振器中的杂散模式，使得体声波谐振器可以具有较高的品质因数。通常情况下，上述空气间隙7的宽度通常需要不小于2μm。为了限制本发明实施例中所提供的混合声波谐振器的尺寸，上述空气间隙7的宽度通常不大于30μm。
可以理解的是，上述任一个沟槽4中可以不仅仅设置一个体声波电极6。以三个相互平行的沟槽4为例，三个相互平行的沟槽4之间可以形成两个体声波传播部5，其中位于中间的沟槽4的两个内侧壁分别为两个不同的体声波传播部5的侧表面，从而上述位于中间的沟槽4中的两个内侧壁均设置有上述体声波电极6，在该沟槽4中一共设置有两个体声波电极6。需要说明的是，上述位于同一沟槽4内的两个体声波电极6之间同样需要设置上述空气间隙7。
本发明实施例所提供的一种混合声波谐振器，在压电薄膜2背向衬底1一侧表面第一区域设置有叉指电极3，构成有叉指换能器，从而使得混合声波谐振器中包括有声表面波谐振器；在压电薄膜2背向衬底1一侧表面第二区域设置有至少两个沟槽4，相邻沟槽4之间形成体声波传播部5，在体声波传播部5侧表面设置有体声波电极6，在体声波电极6背向体声波传播部5一侧表面设置有空气间隙7。上述空气间隙7、体声波电极6以及体声波传播部5构成了体声波谐振器，从而使得混合声波谐振器中同时设置有声表面波谐振器和体声波谐振器，实现了不同种类谐振器的集成；同时在体声波传播部5中传递的声波以及在叉指换能器中传递的声波均是沿水平方向传递，从而可以保证在使用同一种衬底1时声表面波谐振器和体声波谐振器均具有良好的性能。
有关本发明所提供的混合声波谐振器的具体结构将在下述发明实施例 中做详细介绍。
请参考图3以及图4，图3为本发明实施例所提供的一种具体的混合声波谐振器的结构示意图；图4为图3中沿A-A线的剖视图。
区别于上述发明实施例，本发明实施例是在上述发明实施例的基础上，进一步的对混合声波谐振器的结构进行具体限定。其余内容已在上述发明实施例中进行了详细介绍，在此不再进行赘述。
参见图3以及图4，在本发明实施例中，所述混合声波谐振器中压电薄膜2可以为单晶压电薄膜2。上述单晶压电薄膜2，例如单晶铌酸锂薄膜或单晶钽酸锂薄膜中耦合系数较强的方向是与衬底1表面平行的水平方向，该水平方向也是本发明实施例所提供的混合声波谐振器中声表面波谐振器与体声波谐振器的声波传播方向。即上述体声波谐振器中声波传播的方向与声表面波谐振器中声波传播方向均为单晶压电薄膜2中耦合系数较大的方向，从而利用上述单晶压电薄膜2横向耦合系数较大的优点制作而成的混合声波谐振器中，无论是体声波谐振器还是声表面波谐振器均具有较高的品质因数。
在本发明实施例中，所述谐振器还可以包括位于所述衬底1与所述压电薄膜2之间的具有正频率温度系数的介质层8。所谓正频率温度系数(TCF)即随着温度的升高，该介质层8的固有频率会随之升高，即介质层8的固有频率与温度成正相关。由于通常情况下在本发明实施例所提供的混合声波谐振器中各个结构的材料通常均为具有负频率温度系数的材料。当环境温度发生变化时，通常情况下现阶段谐振器所用的材料的固有频率均会随着环境温度的升高而降低，从而影响混合声波谐振器的温度稳定性。而在衬底1与压电薄膜2之间设置的具有正频率温度系数的介质层8可以有效改善谐振器的温度系数，使得谐振器的固有频率不会随着环境温度的变化有太明显的波动，从而使得谐振器具有良好的温度稳定性。
具体的，在本发明实施例中，上述介质层8的材质具体可以为氧化硅(SiO 2)、掺氟(F)的氧化硅，掺硼(B)的氧化硅等等，有关介质层8的具体材质在本发明实施例中并不做具体限定。
在本发明实施例中，所述谐振器还可以包括位于所述压电薄膜2背向所述衬底1一侧表面的多个第一焊盘91和多个第二焊盘92；所述第一焊盘91与所述叉指电极3中的母线电连接；所述第二焊盘92与所述体声波电极6电连接。
上述第一焊盘91通常是本发明实施例所提供的混合声波谐振器中声表面波谐振器与其他部件的连接点，而第二焊盘92通常是体声波器件与其他部件的连接点。上述第一焊盘91以及第二焊盘92通常均设置在压电薄膜2背向衬底1一侧表面，其中上述第一焊盘91通常需要与叉指电极3中母线一一对应，上述第一焊盘91通常需要与对应的母线相互接触以与叉指电极3电连接；上述第二焊盘92通常需要与体声波电极6一一对应，上述第二焊盘92通常需要与对应的体声波电极6相互接触以与体声波电极6电连接。
具体的，在本发明实施例中，上述第一焊盘91以及第二焊盘92的材质具体可以为铬(Cr)、镍(Ni)、钨(W)、钛钨(TiW)、铝(Al)、铜(Cu)、金(Au)中的一种，或者是由上述材质中多种材质复合而成。当然，有关第一焊盘91以及第二焊盘92的具体材质在本发明实施例中并不做具体限定，视具体情况而定。
通常情况在，在本发明实施例中会在压电薄膜2背向衬底1一侧表面第一区域中，沿母线延长线方向在叉指电极3的两侧设置有反射栅。所述反射栅用于反射声波，通过反射栅可以将声表面波谐振器中的声波限制在叉指换能器中，从而可以避免声波能量从叉指换能器两侧损失。
本发明实施例所提供的一种混合声波谐振器，通过使用单晶压电薄膜2可以保证无论是体声波谐振器还是声表面波谐振器均具有较高的品质因数；通过设置具有正频率温度系数的介质层8可以使得谐振器的固有频率不会随着环境温度的变化有太明显的波动；通过设置第一焊盘91以及第二焊盘92可以便于混合声波器件与其他部件相互电连接。
下面对本发明所提供的一种混合声波谐振器的制备方法进行介绍，下文描述的制备方法与上述描述的混合声波谐振器的结构可以相互对应参 照。
请参考图5至图9，图5至图9为本发明实施例所提供的一种混合声波谐振器制备方法的工艺流程图。
参见图5，在本发明实施例中，所述混合声波谐振器的制备方法包括：
S101：在衬底的表面设置压电薄膜。
参见图6，在本步骤中，通常是将预先制备好的压电薄膜2键合在预先制备好的衬底1表面。有关具体的键合方法可以参考现有技术，在本发明实施例中并不做具体限定。
有关上述衬底1以及压电薄膜2的具体材质已在上述发明实施例中做详细介绍，在此不再进行赘述。需要说明的是，上述压电薄膜2表面通常分为第一区域以及第二区域。
在本步骤之后，通常会对压电薄膜2进行研磨以及抛光，以使压电薄膜2达到预设的厚度，该厚度通常由构成体声波(BAW)滤波器的单个体声波谐振器的最大面积决定，例如若体声波谐振器的最大面积为S，则在研磨以及抛光之后压电薄膜2剩余的厚度需大于等于
Figure PCTCN2018115041-appb-000001
除了上述对压电薄膜2进行研磨以及抛光的方式对压电薄膜2进行减薄之外，可以通过在键合之前先对压电薄膜2的待键合面进行粒子注入，以在预设的厚度处形成改质层；再将压电薄膜2进行键合时，可以通过低温退火，使得压电薄膜2从上述改质层处分离，从而留下预设厚度的压电薄膜2。该预设厚度的压电薄膜2会与衬底1固定连接，从而实现对压电薄膜2的减薄处理。
S102：在压电薄膜表面的第一区域设置叉指电极。
参见图7，在本步骤中，需要在压电薄膜2表面的第一区域设置叉指电极3，以形成叉指换能器，通过上述叉指换能器即可构成最基本的声表面波谐振器。有关叉指换能器的具体结构已在上述发明实施例中做详细介绍，在此不再进行赘述。
具体的，在本步骤中可以通过多种方法在压电薄膜2表面的第一区域设置叉指电极3，例如：第一种，可以先在压电薄膜2表面溅射一导电层；再刻蚀该导电层以对该导电层图案化，从而在压电薄膜2表面的第一区域形成上述叉指电极3。
第二种，可以先在压电薄膜2表面设置一胶层；其次，刻蚀该胶层，以暴露压电薄膜2表面需要设置叉指电极3的区域；再次，在上述胶层表面溅射一导电层，该导电层同样会覆盖压电薄膜2表面中被暴露出的需要设置叉指电极3的区域；最后，剥离上述胶层，此时会将覆盖在胶层表面的导电层同步剥离，以在压电薄膜2表面的第一区域形成上述叉指电极3。
当然，除了上述两种方法外，还可以使用其它方法设置上述叉指电极3，有关叉指电极3具体的设置方法在本发明实施例中并不做具体限定。本发明实施例可以根据实际情况灵活的选用不同方法设置叉指电极3。
S103：在压电薄膜表面的第二区域刻蚀至少两个沟槽。
参见图8，在本发明实施例中，相邻所述沟槽4之间形成体声波传播部5，所述体声波传播部5具有相对的两个侧表面。
在本步骤中，会刻蚀压电薄膜2表面的第二区域以形成上述沟槽4。有关沟槽4的具体结构已在上述发明实施例中做详细介绍，在此不再进行赘述。在本步骤中通常会刻蚀透所述压电薄膜2。有关具体的刻蚀工艺可以参考现有技术，在此不再进行赘述。
由于在本发明实施例中体声波谐振器工作的频率与上述体声波传播部5的厚度有关，即与相邻沟槽4之间的距离有关，所以在本步骤中上述沟槽4之间间距的选择需要根据不同应用的设计自行决定，在本发明实施例中并不做具体限定。
S104：在沟槽内设置分别位于体声波传播部侧表面的体声波电极，以制成混合声波谐振器。
参见图9，在本发明实施例中，所述体声波电极6背向所述体声波传播部5一侧表面设置有空气间隙7。
在本步骤中会在上述沟槽4内形成位于体声波传播部5侧表面的体声波电极6，而每个体声波传播部5的两个侧表面通常均需要设置有体声波 电极6。需要说明的是，在上述体声波电极6背向体声波传播部5一侧表面通常需要设置有用于限制声波传播的空气间隙7，以最终制成本发明实施例所提供的混合声波谐振器。有关设置上述体声波电极6以及空气间隙7的具体步骤将在下述发明实施例中做详细介绍，在此不再进行赘述。
需要说明的是，在本发明实施例中S102为主要形成声表面波谐振器的步骤，而S103和S104为主要形成体声波谐振器的步骤，上述S103以及S104与S102之间并没有明确的先后顺序，即在本发明实施例中可以先在压电薄膜2表面形成叉指电极3以构成声表面波谐振器，再在压电薄膜2中设置体声波电极6以构成体声波谐振器；可以先在压电薄膜2中设置体声波电极6以构成体声波谐振器，再在压电薄膜2表面形成叉指电极3以构成声表面波谐振器。其具体顺序可以根据实际情况自行设定，在本发明实施例中并不做具体限定。
本发明实施例所提供的一种混合声波谐振器的制备方法，所制备而成的混合声波谐振器，在压电薄膜2背向衬底1一侧表面第一区域设置有叉指电极3，构成有叉指换能器，从而使得混合声波谐振器中包括有声表面波谐振器；在压电薄膜2背向衬底1一侧表面第二区域设置有至少两个沟槽4，相邻沟槽4之间形成体声波传播部5，在体声波传播部5侧表面设置有体声波电极6，在体声波电极6背向体声波传播部5一侧表面设置有空气间隙7。上述空气间隙7、体声波电极6以及体声波传播部5构成了体声波谐振器，从而使得混合声波谐振器中同时设置有声表面波谐振器和体声波谐振器，实现了不同种类谐振器的集成；同时在体声波传播部5中传递的声波以及在叉指换能器中传递的声波均是沿水平方向传递，从而可以保证在使用同一种衬底1时声表面波谐振器和体声波谐振器均具有良好的性能。
有关上述混合声波谐振器具体的制备步骤将在下述发明实施例中进行详细介绍。
请参考图10至图16，图10至图16为本发明实施例所提供的一种具体的混合声波谐振器制备方法的工艺流程图。
参见图10，在本发明实施例中，所述混合声波谐振器的制备方法包括：
S201：在衬底的表面设置具有正频率温度系数的介质层。
参见图11，有关上述介质层8的具体材质以及该介质层8所起到的作用已在上述发明实施例中做详细介绍，在此不再进行赘述。在本步骤中，通常是用薄膜沉积的工艺在衬底1的表面沉积一层具有正频率温度系数的介质层8。通过先在衬底1表面沉积上述介质层8也便于后续键合压电薄膜2。
S202：在介质层表面键合压电薄膜。
参见图12，在本步骤中，具体会在上述介质层8表面键合压电薄膜2，以使压电薄膜2与衬底1固定连接。本步骤的其余内容与上述发明实施例中S101基本相同，详细内容请参考上述发明实施例，在此不再进行赘述。
S203：在压电薄膜表面的第一区域设置叉指电极。
参见图13，本步骤与上述发明实施例中S102基本相同，详细内容已在上述发明实施例中做详细介绍，在此不再进行赘述。
S204：在压电薄膜表面的第一区域设置覆盖叉指电极的保护层。
在本步骤中，会在制备体声波谐振器之前，在已经设置好的叉指电极3表面覆盖一层保护层，以防止后续在制备体声波谐振器时对该叉指电极3的形貌造成影响，从而影响声表面波器件的性能。所述保护层可以是光刻胶等等，有关上述保护层的具体材质以及具体厚度可以参考现有技术，在此不再进行赘述。
S205：在设置完叉指电极之后，在压电薄膜表面的第二区域刻蚀至少两个沟槽。
参见图14，在本发明实施例中，具体会先在压电薄膜2表面形成叉指电极3以构成声表面波谐振器，再在压电薄膜2中设置体声波电极6以构成体声波谐振器。因为若先设置上述沟槽4以及体声波电极6，会使得压电薄膜2表面不再平整，而在压电薄膜2表面设置叉指电极3时，压电薄膜2表面优选为平整表面。所以在本发明实施例中，通常是先在压电薄膜2表面形成叉指电极3以构成声表面波谐振器，再在压电薄膜2中设置体声波电极6以构成体声波谐振器。
本步骤的其余内容与上述发明实施例中S103基本相同，详细内容请参考上述发明实施例，在此不再进行赘述。
S206：在沟槽内设置导电层。
参见图15，在本步骤中，具体可以采用原子层沉积(ALD)工艺、电镀工艺或者是保形性较好的溅射工艺在上述沟槽内沉积一导电层61，该导电层61可以充满整个沟槽4或只覆盖在沟槽4的底部和侧壁。有关导电层61具体的材质可以参考上述发明实施例中体声波电极6的材质，在此不再进行赘述。
S207：图形化导电层，以形成空气间隙和体声波电极。
参见图16，在本步骤中具体可以采用剥离工艺，或者刻蚀工艺对上述设置在沟槽4内的导电层61图案化，以制出上述发明实施例中所述的空气间隙7，同时将上述导电层61制为体声波电极6。有关具体图案化的工艺可以参考现有技术，在此不再进行赘述。
S208：去除保护层。
在本步骤中会去除在S204中设置的保护层，已裸露上述叉指电极3。当然，若在S208之前没有在叉指电极3表面设置保护层，又或者上述保护层为不需要去除的，可以起到温度补偿作用的保护层，例如二氧化硅层等等，则不需要执行本步骤。
在本步骤之后，还可以继续在压电薄膜2表面设置上述发明实施例中所述的第一焊盘91以及第二焊盘92。有关第一焊盘91以及第二焊盘92具体的制备工艺可以参考现有技术，在此不再进行赘述。
本发明实施例所提供的一种混合声波谐振器的制备方法，通过设置具有正频率温度系数的介质层8可以使得谐振器的固有频率不会随着环境温度的变化有太明显的波动；通过设置上述保护层可以有效保护叉指电极3在后续步骤中不易被损坏；通过先设置叉指电极3，再设置体声波电极6可以有效保证叉指电极3具有良好的形貌。
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其它实施例的不同之处，各个实施例之间相同或相似部分互相参见 即可。对于实施例公开的装置而言，由于其与实施例公开的方法相对应，所以描述的比较简单，相关之处参见方法部分说明即可。
专业人员还可以进一步意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、计算机软件或者二者的结合来实现，为了清楚地说明硬件和软件的可互换性，在上述说明中已经按照功能一般性地描述了各示例的组成及步骤。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本发明的范围。
结合本文中所公开的实施例描述的方法或算法的步骤可以直接用硬件、处理器执行的软件模块，或者二者的结合来实施。软件模块可以置于随机存储器(RAM)、内存、只读存储器(ROM)、电可编程ROM、电可擦除可编程ROM、寄存器、硬盘、可移动磁盘、CD-ROM、或技术领域内所公知的任意其它形式的存储介质中。
最后，还需要说明的是，在本文中，诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括一个……”限定的要素，并不排除在包括所述要素的过程、方法、物品或者设备中还存在另外的相同要素。
以上对本发明所提供的一种混合声波谐振器及其制备方法进行了详细介绍。本文中应用了具体个例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的方法及其核心思想。应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以对本发明进行若干改进和修饰，这些改进和修饰也落入本发明权利要求的保护范围内。

Claims (10)

  1. 一种混合声波谐振器，其特征在于，包括：
    衬底；
    位于所述衬底表面的压电薄膜；
    位于所述压电薄膜背向所述衬底一侧表面第一区域的叉指电极；
    位于所述压电薄膜背向所述衬底一侧表面第二区域的至少两个沟槽；其中，相邻所述沟槽之间形成体声波传播部，所述体声波传播部具有相对的两个侧表面；
    分别位于所述体声波传播部侧表面的体声波电极；其中，所述体声波电极背向所述体声波传播部一侧表面设置有空气间隙。
  2. 根据权利要求1所述的谐振器，其特征在于，所述压电薄膜为单晶压电薄膜。
  3. 根据权利要求1所述的谐振器，其特征在于，所述沟槽相互平行。
  4. 根据权利要求3所述的谐振器，其特征在于，所述空气间隙的宽度不小于2μm。
  5. 根据权利要求1至4任一项权利要求所述的谐振器，其特征在于，所述谐振器还包括：
    位于所述衬底与所述压电薄膜之间的具有正频率温度系数的介质层。
  6. 根据权利要求1所述的谐振器，其特征在于，所述谐振器还包括：
    位于所述压电薄膜背向所述衬底一侧表面的多个第一焊盘和多个第二焊盘；所述第一焊盘与所述叉指电极中的母线电连接；所述第二焊盘与所述体声波电极电连接。
  7. 一种混合声波谐振器的制备方法，其特征在于，包括：
    在衬底的表面设置压电薄膜；
    在所述压电薄膜表面的第一区域设置叉指电极；
    在所述压电薄膜表面的第二区域刻蚀至少两个沟槽；其中，相邻所述沟槽之间形成体声波传播部，所述体声波传播部具有相对的两个侧表面；
    在所述沟槽内设置分别位于所述体声波传播部侧表面的体声波电极，以制成所述混合声波谐振器；其中，所述体声波电极背向所述体声波传播 部一侧表面设置有空气间隙。
  8. 根据权利要求7所述的方法，其特征在于，所述在所述沟槽内设置分别位于所述体声波传播部侧表面的体声波电极包括：
    在所述沟槽内设置导电层；
    图形化所述导电层，以形成所述空气间隙和所述体声波电极。
  9. 根据权利要求7所述的方法，其特征在于，在所述在衬底的表面设置压电薄膜之前，所述方法还包括：
    在衬底的表面设置具有正频率温度系数的介质层；
    所述在衬底的表面设置压电薄膜包括：
    在所述介质层表面键合所述压电薄膜。
  10. 根据权利要求7至9任一项权利要求所述的方法，其特征在于，在所述压电薄膜表面的第一区域设置叉指电极之后，所述方法还包括：
    在所述压电薄膜表面的第一区域设置覆盖所述叉指电极的保护层；
    所述在所述压电薄膜表面的第二区域刻蚀至少两个沟槽包括：
    在设置完所述叉指电极之后，在所述压电薄膜表面的第二区域刻蚀至少两个所述沟槽；
    在所述沟槽内设置分别位于所述体声波传播部侧表面的体声波电极之后，所述方法还包括：
    去除所述保护层。
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