WO2019056553A1 - 压电谐振器的制备方法和压电谐振器 - Google Patents

压电谐振器的制备方法和压电谐振器 Download PDF

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WO2019056553A1
WO2019056553A1 PCT/CN2017/112543 CN2017112543W WO2019056553A1 WO 2019056553 A1 WO2019056553 A1 WO 2019056553A1 CN 2017112543 W CN2017112543 W CN 2017112543W WO 2019056553 A1 WO2019056553 A1 WO 2019056553A1
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piezoelectric
single crystal
material layer
piezoelectric material
polycrystalline
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PCT/CN2017/112543
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English (en)
French (fr)
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左成杰
何军
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安徽安努奇科技有限公司
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Priority claimed from CN201710864033.4A external-priority patent/CN107508571A/zh
Priority claimed from CN201721220998.1U external-priority patent/CN207166465U/zh
Application filed by 安徽安努奇科技有限公司 filed Critical 安徽安努奇科技有限公司
Priority to JP2018557889A priority Critical patent/JP6781271B2/ja
Priority to US16/096,265 priority patent/US20210234527A1/en
Priority to KR1020187035769A priority patent/KR102135522B1/ko
Publication of WO2019056553A1 publication Critical patent/WO2019056553A1/zh

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • 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
    • 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
    • H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
    • 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
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/05—Manufacture of multilayered piezoelectric or electrostrictive devices, or parts thereof, e.g. by stacking piezoelectric bodies and electrodes
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/07—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
    • H10N30/074—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing
    • H10N30/076—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing by vapour phase deposition
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/09—Forming piezoelectric or electrostrictive materials
    • H10N30/092—Forming composite materials
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/852—Composite materials, e.g. having 1-3 or 2-2 type connectivity

Definitions

  • the present disclosure relates to the field of piezoelectric devices, and, for example, to a method of fabricating a piezoelectric resonator and a piezoelectric resonator.
  • FBAR Film Bulk Acoustic Resonator
  • piezoelectric film bulk acoustic resonator Its principle is to use the inverse piezoelectric effect of piezoelectric film to convert the input high frequency electrical signal into acoustic signal of a certain frequency. And generate resonance where the acoustic loss at the resonant frequency is minimal.
  • Piezoelectric resonance technology can be used to prepare more advanced electronic components and provide a wider range of applications for communication technologies.
  • a piezoelectric resonator includes two electrodes disposed opposite to each other and a piezoelectric film between the two electrodes.
  • a piezoelectric thin film is usually prepared by using a single crystal aluminum nitride AlN piezoelectric material or a polycrystalline aluminum nitride AlN piezoelectric material, but the growth or deposition speed of the single crystal AlN piezoelectric material is slow, and the internal stress is difficult to control and increase.
  • the present disclosure provides a method for fabricating a piezoelectric resonator and a piezoelectric resonator, which can relatively easily prepare a piezoelectric film having a relatively thick thickness, can easily realize a piezoelectric resonator of a low frequency band, and reduce production cost and process difficulty. Moreover, the performance of the piezoelectric resonator can be improved, and the crystallinity of the polycrystalline piezoelectric material is higher.
  • the present disclosure provides a method of fabricating a piezoelectric resonator, comprising:
  • a polycrystalline piezoelectric material layer is formed on a surface of the single crystal piezoelectric material layer away from the first substrate side.
  • the present disclosure also provides a piezoelectric resonator, comprising:
  • a first electrode formed on a surface of the polycrystalline piezoelectric material layer away from a side of the single crystal piezoelectric material layer;
  • the present disclosure provides a method of fabricating a piezoelectric resonator and a piezoelectric resonator by forming a single crystal piezoelectric material layer on a first substrate and then forming a polycrystalline piezoelectric material layer on the single crystal piezoelectric material layer.
  • the piezoelectric resonator can be optimized by adjusting the thickness ratio of the single crystal piezoelectric material layer and the polycrystalline piezoelectric material layer.
  • the overall cost performance can be achieved by adjusting the total thickness of the piezoelectric film to achieve a low-band piezoelectric resonator.
  • a thin single crystal piezoelectric material layer and a thick polycrystalline piezoelectric material layer can be formed to reduce production cost and process difficulty; meanwhile, due to single crystal piezoelectric material The crystallinity is high. Therefore, the lattice starting point of the polycrystalline piezoelectric material deposited on the single crystal piezoelectric material layer is arranged more neatly, thereby improving the crystallinity of the polycrystalline piezoelectric material in the polycrystalline piezoelectric material layer and improving The performance of the piezoelectric resonator.
  • FIG. 1 is a flow chart of a method for fabricating a piezoelectric resonator according to Embodiment 1;
  • FIGS. 2 to 3 are schematic cross-sectional structural views of piezoelectric resonators corresponding to respective steps in the preparation flow provided in the first embodiment
  • FIG. 4 is a flow chart of a method for fabricating a piezoelectric resonator according to Embodiment 2;
  • FIG. 5 is a flow chart of a method for fabricating a piezoelectric resonator according to Embodiment 3;
  • FIG. 6 is a flow chart of a method for fabricating a piezoelectric resonator according to Embodiment 4.
  • FIG. 7 is a flow chart of a method for fabricating a piezoelectric resonator according to Embodiment 5;
  • FIG. 8 to FIG. 11 are schematic cross-sectional structural views of piezoelectric resonators corresponding to respective steps in the electrode preparation flow provided in the fifth embodiment;
  • FIG. 12 is a schematic structural view of a piezoelectric resonator provided in Embodiment 6.
  • FIG. 1 is a flow chart of a method for fabricating a piezoelectric resonator according to a first embodiment
  • FIG. 2 to FIG. 3 are schematic cross-sectional views of a piezoelectric resonator corresponding to each step in the preparation flow provided in the first embodiment.
  • This embodiment can be applied to the case of improving the performance of a piezoelectric resonator.
  • the manufacturing method of the piezoelectric resonator provided by this embodiment includes:
  • Step 110 forming a single crystal piezoelectric material layer on the first substrate.
  • a single crystal piezoelectric material layer 11 is formed on the first substrate 10, wherein the material of the single crystal piezoelectric material layer 11 may be a single crystal AlN, which may be formed by an epitaxial method.
  • the epitaxial method may include metal organic chemical vapor deposition (MOCVD), also known as metal organic chemical vapor phase epitaxy (MOVPE), and aluminum organic matter (generally trimethylaluminum) may be selected as the aluminum source, and ammonia gas as the reaction.
  • MOCVD metal organic chemical vapor deposition
  • MOVPE metal organic chemical vapor phase epitaxy
  • aluminum organic matter generally trimethylaluminum
  • the nitrogen source can input the organic aluminum source and the excess ammonia gas into the vacuum reaction chamber under the carrier gas hydrogen transport. Under the action of high temperature, the organic aluminum source reacts with the ammonia gas to produce high quality.
  • the single crystal piezoelectric material may also be zinc oxide (ZnO), lithium niobate (LiTaO 3 ), or lithium niobate (LiNbO 3 ), etc., and a single crystal is formed on the first substrate by using the above material. Piezoelectric material layer 11.
  • Step 120 forming a polycrystalline piezoelectric material layer on a surface of the single crystal piezoelectric material layer away from the first substrate side.
  • a polycrystalline piezoelectric material layer 12 may be formed on the surface of the single crystal piezoelectric material layer 11 away from the first substrate 10 by a deposition method.
  • the material of the polycrystalline piezoelectric material layer 12 and the single crystal piezoelectric material layer 11 may be the same or different.
  • the material of the polycrystalline piezoelectric material layer 12 may be polycrystalline AlN
  • the deposition method may be a radio frequency magnetron sputtering deposition technique, and a high purity aluminum Al target (99.99%) may be utilized, and a high purity argon Ar, Nitrogen N 2 is used as a sputtering gas and a reaction gas, respectively, on the basis of preparing a high quality single crystal AlN material layer, by adjusting experimental parameters (such as working pressure, substrate temperature, N 2 flow rate, target distance, etc.) A polycrystalline AlN film material was prepared.
  • the single crystal piezoelectric material layer 11 is formed on the first substrate 10, the crystallinity of the single crystal piezoelectric material layer 11 is high, and the polycrystalline piezoelectric material 12 deposited on the surface of the single crystal piezoelectric material layer 11 can be arranged more.
  • the neat lattice starting point can thus make the polycrystalline AlN piezoelectric material deposited on the first substrate 10 have higher crystallinity and better performance.
  • the polycrystalline piezoelectric material may alternatively be zinc oxide (ZnO), lead zirconate titanate piezoelectric ceramic (PZT), lithium niobate (LiTaO 3 ) or lithium niobate (LiNbO 3 ), etc., and may be used.
  • the above material forms a polycrystalline piezoelectric material layer 12 on the prepared single crystal piezoelectric material layer 11.
  • the method for preparing a piezoelectric resonator provides a method of forming a single crystal piezoelectric material layer on a first substrate and forming a polycrystalline piezoelectric material layer on the single crystal piezoelectric material layer.
  • a piezoelectric film composed of a single crystal piezoelectric material layer and a polycrystalline piezoelectric material layer can optimize the comprehensive cost performance of the piezoelectric resonator by adjusting the thickness ratio of the single crystal piezoelectric material layer and the polycrystalline piezoelectric material layer.
  • a low-band piezoelectric resonator can be realized by adjusting the total thickness of the piezoelectric film, and in the case of realizing a low-band piezoelectric resonator, a thin single-crystal piezoelectric material layer and a thick polycrystalline piezoelectric material can be formed.
  • the total thickness of the single crystal piezoelectric material layer 11 and the polycrystalline piezoelectric material layer 12 is greater than or equal to 1.5 ⁇ m, which can satisfy the resonant frequency of the piezoelectric resonator. It is required for 100MHz to 3GHz (low frequency band).
  • step 110 forming a single crystal piezoelectric material layer on the first substrate comprises:
  • a single crystal substrate is provided; single crystal AlN is epitaxially grown on the single crystal substrate to form a single crystal AlN piezoelectric layer.
  • the single crystal AlN piezoelectric layer is also the above single crystal piezoelectric material layer.
  • the polycrystalline piezoelectric material layer is the same material as the single crystal piezoelectric material layer.
  • forming a polycrystalline piezoelectric material layer on a surface of the single crystal piezoelectric material layer away from the first substrate side comprises: separating the first single substrate from the single crystal AlN piezoelectric layer Polycrystalline AlN is deposited on the surface of the side to form a polycrystalline AlN piezoelectric layer. As shown in FIG. 4, the method in this embodiment includes:
  • Step 210 providing a single crystal substrate
  • the single crystal substrate provided may be a single crystal substrate such as silicon carbide SiC, sapphire or gallium nitride GaN, because AlN is a Important
  • the III-V nitride has a stable wurtzite structure, so that the lattice mismatch and thermal mismatch of the AlN film prepared on the above substrate are relatively small, thereby reducing defects in the preparation of the film and reducing the lattice. The effect of mismatch on film quality.
  • AlN materials can maintain piezoelectricity at high temperatures, so AlN piezoelectric thin film devices can be adapted to high temperature working environments. Good chemical stability also allows AlN piezoelectric films to adapt to corrosive working conditions.
  • the AlN material also has good heat transfer characteristics, which makes the acoustic wave device made of AlN not reduce the service life of the device due to work heat generation. Therefore, AlN can be used as the material of the single crystal piezoelectric material layer 11.
  • Step 220 epitaxially growing single crystal AlN on the single crystal substrate to form a single crystal AlN piezoelectric layer.
  • single crystal AlN is epitaxially grown on a single crystal substrate, and the epitaxial growth method of single crystal AlN may be metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), pulsed laser deposition (PLD) or radio frequency magnetron sputtering. method.
  • MOCVD metal organic chemical vapor deposition
  • MBE molecular beam epitaxy
  • PLD pulsed laser deposition
  • single crystal AlN can be grown by a metal organic chemical vapor deposition (MOCVD) method.
  • MOCVD metal organic chemical vapor deposition
  • aluminum organic matter which may be trimethylaluminum
  • ammonia gas is used as the nitrogen source
  • the organic aluminum source and excess ammonia are transported under the carrier gas hydrogen transport.
  • the gas is input into the vacuum reaction chamber, and under the action of high temperature, the organic aluminum source reacts with the ammonia gas to produce a single crystal AlN film deposited on the surface of the substrate.
  • the composition, growth thickness and uniformity of the single crystal AlN film can be strictly controlled by MOCVD method to prepare high quality single crystal AlN film material, which is suitable for mass production of single crystal A1l film.
  • Step 230 depositing polycrystalline AlN on a surface of the single crystal AlN piezoelectric layer away from the first substrate to form a polycrystalline AlN piezoelectric layer.
  • polycrystalline AlN is deposited on the surface of the single crystal AlN piezoelectric layer away from the first substrate 10 to form a polycrystalline AlN piezoelectric layer
  • the deposition method may be a radio frequency magnetron sputtering deposition method using high purity Al
  • the target (99.99%), with high purity Ar and N 2 as sputtering gas and reaction gas, respectively, on the basis of preparing a high quality single crystal AlN material layer, through experimental parameters (for example: working pressure, substrate temperature,
  • the polycrystalline AlN thin film material was prepared by adjusting the N 2 flow rate and the target distance.
  • the single crystal piezoelectric material layer 11 is formed on the first substrate 10, the crystallinity of the single crystal piezoelectric material layer 11 is high, and the polycrystalline piezoelectric material deposited on the surface thereof can have a more uniform lattice starting point.
  • the polycrystalline AlN piezoelectric material deposited on the first substrate 10 can be made to have higher crystallinity and better performance.
  • the thickness of the single crystal AlN piezoelectric layer is less than 0.6 ⁇ m.
  • the single crystal AlN piezoelectric layer is grown to 0.6 ⁇ m or more, the growth process time is long, and the process problems are many. Due to the limitation of process and production requirements, the thicker single crystal AlN piezoelectric layer will greatly increase the production cost and reduce the production. Yield, therefore, it is difficult to prepare a high-performance low-frequency (for example, 1 GHz or less) piezoelectric resonator by a single-crystal AlN piezoelectric layer.
  • the thickness of the single crystal AlN piezoelectric layer is less than 0.6 ⁇ m, and the thickness of the piezoelectric film is increased by depositing a polycrystalline AlN piezoelectric layer.
  • the resonant frequency of the piezoelectric resonator is required to be 2 GHz, if the piezoelectric film is corresponding.
  • the thickness of the piezoelectric layer of the single crystal AlN may be 0.5 ⁇ m or less, and the thickness of the piezoelectric layer of the polycrystalline AlN may be 1 ⁇ m, thereby saving time for preparing the piezoelectric layer of the single crystal AlN. The overall preparation time is shortened, the process problem is reduced, and the piezoelectric resonator of low frequency band and high performance is realized.
  • the method for preparing a piezoelectric resonator provides epitaxial growth of single crystal AlN on a single crystal substrate, which can reduce AlN lattice mismatch and thermal mismatch, facilitate single crystal AlN crystallization, and reduce lattice
  • the effect of mismatch on the quality of the piezoelectric film; deposition of a polycrystalline AlN piezoelectric layer on a single-crystal AlN piezoelectric layer compared to resonators and filters implemented solely with polycrystalline AlN (mainstream mass production products in the field) can reduce losses, achieve high Q and low insertion loss.
  • FIG. 5 is a flow chart of a method for fabricating a piezoelectric resonator according to Embodiment 3.
  • This embodiment is different from the above embodiment 2 in that the polycrystalline piezoelectric material layer is different from the material of the single crystal piezoelectric material layer; correspondingly, optionally, the single crystal piezoelectric material layer is away from the first substrate side.
  • the surface forming the polycrystalline piezoelectric material layer comprises: depositing polycrystalline zinc oxide on the surface of the single crystal AlN piezoelectric layer away from the first substrate by a deposition method to form a ZnO piezoelectric layer.
  • the method in this embodiment includes:
  • Step 310 providing a single crystal substrate
  • Step 320 epitaxially growing single crystal AlN on the single crystal substrate to form a single crystal AlN piezoelectric layer.
  • Step 330 depositing polycrystalline zinc oxide on the surface of the single crystal AlN piezoelectric layer away from the first substrate by a deposition method to form a ZnO piezoelectric layer.
  • ZnO thin film has high piezoelectricity (piezoelectric constant d 33 ⁇ 12 pm / V), and its structure is also wurtzite structure, which can form good lattice matching and reduce on the basis of single crystal AlN thin film. The effect of lattice mismatch on the quality of polycrystalline ZnO thin films.
  • polycrystalline zinc oxide is deposited on the surface of the single crystal AlN piezoelectric layer away from the first substrate 10 to form a polycrystalline ZnO piezoelectric layer
  • the deposition method may be a radio frequency magnetron sputtering deposition method using ZnO
  • the ceramic target 99.9%
  • high purity O 2 and Ar as the reaction gas and shielding gas respectively
  • the polycrystalline ZnO piezoelectric layer was prepared by adjusting the temperature, deposition time, and target distance.
  • the single crystal piezoelectric material layer 11 is formed on the first substrate 10, the crystallinity of the single crystal piezoelectric material layer 11 is high, and the polycrystalline piezoelectric material deposited on the surface thereof can have a more uniform lattice starting point.
  • the polycrystalline ZnO piezoelectric material deposited on the first substrate can be made to have higher crystallinity and better performance.
  • polycrystalline ZnO is deposited on the piezoelectric layer of the single crystal AlN, and the piezoelectric coupling coefficient k t of the piezoelectric resonator can be improved relative to the polycrystalline AlN piezoelectric layer. 2 , thereby improving the performance of the piezoelectric resonator.
  • FIG. 6 is a schematic flow chart of a method for fabricating a piezoelectric resonator according to Embodiment 4.
  • the difference between the embodiment and the second embodiment is that the polycrystalline piezoelectric material layer is different from the material of the single crystal piezoelectric material layer; correspondingly, the surface of the single crystal piezoelectric material layer away from the first substrate is formed.
  • the layer of crystalline piezoelectric material comprises: depositing a lead zirconate titanate piezoelectric ceramic on a surface of the single crystal AlN piezoelectric layer away from the first substrate by a deposition method to form a PZT piezoelectric layer.
  • the method in this embodiment includes:
  • Step 410 providing a single crystal substrate
  • Step 420 epitaxially growing single crystal AlN on the single crystal substrate to form a single crystal AlN piezoelectric layer.
  • Step 430 depositing a lead zirconate titanate piezoelectric ceramic on the surface of the single crystal AlN piezoelectric layer away from the first substrate by a deposition method to form a PZT piezoelectric layer.
  • PZT film has force-electric coupling performance, and its piezoelectric coupling coefficient k t 2 is high, which is a superior material for making wide bandwidth filter.
  • a polycrystalline PZT piezoelectric ceramic is deposited on the surface of the single crystal AlN piezoelectric layer away from the first substrate 10 to form a polycrystalline PZT piezoelectric layer, and the deposition method may be a pulsed laser deposition method.
  • a krypton fluoride KrF pulse laser is used, and the vacuum is first applied in the experiment, and then oxygen is introduced to reach a certain pressure.
  • the substrate prepared with the high quality single crystal AlN piezoelectric layer is heated to a certain temperature, so that the KrF pulse laser is incident on the PZT target at an angle of 45 ° C, and the atoms of the PZT are ejected from the target onto the substrate. Subsequently, the film was crystallized by slowly cooling to room temperature to prepare a PZT film.
  • the PZT piezoelectric layer was prepared by adjusting experimental parameters such as working pressure, substrate temperature, deposition time, and target distance.
  • a PZT piezoelectric layer is deposited on the single crystal AlN piezoelectric layer, and the piezoelectric coupling coefficient of the piezoelectric resonator can be improved relative to the polycrystalline AlN piezoelectric layer.
  • t 2 which in turn improves the performance of the piezoelectric resonator.
  • FIG. 7 is a flow chart of a method for fabricating a piezoelectric resonator according to Embodiment 5.
  • FIG. 8 to FIG. 11 are schematic cross-sectional structural views of a piezoelectric resonator corresponding to each step in the electrode preparation flow provided in Embodiment 5.
  • the method may further include: moving away from the first layer in the polycrystalline piezoelectric material layer.
  • the method in this embodiment includes:
  • Step 510 forming a single crystal piezoelectric material layer on the first substrate.
  • Step 520 forming a polycrystalline piezoelectric material layer on a surface of the single crystal piezoelectric material layer away from the first substrate side.
  • Step 530 forming a first electrode on a surface of the polycrystalline piezoelectric material layer away from the first substrate side.
  • a first electrode 13 is formed on a surface of the polycrystalline piezoelectric material layer 12 away from the first substrate 10, which may be formed by a magnetron sputtering method, which may be on the polycrystalline piezoelectric material layer 12.
  • a magnetron sputtering method which may be on the polycrystalline piezoelectric material layer 12.
  • Depositing a layer of one or more of tungsten (W), aluminum (Al), copper (Cu), platinum (Pt), silver (Ag), titanium (Ti), and molybdenum (Mo) wherein the first electrode 13 may have a similar shape to the substrate.
  • Step 540 pressing the piezoelectric resonator with the first electrode to the second substrate through the first electrode, and peeling off the first substrate by a thin film transfer process.
  • the first substrate 10 the single crystal piezoelectric material layer 11, and the polycrystalline pressure
  • the electric material layer 12 and the first electrode 13 are turned over and the first electrode 13 is mechanically pressed onto the second substrate 14, so that the first electrode 13 is away from the surface of the single crystal piezoelectric material layer 11 and the surface of the second substrate 14 is bonded.
  • the single crystal piezoelectric material layer 11 is peeled off from the first substrate 10 by laser lift-off or plasma stripping technology, and the peeling rate of the laser lift-off or plasma stripping technology is high, and the peeling process can be avoided as much as possible.
  • the film and the substrate sheet are broken.
  • Step 550 forming a second electrode on a surface of the single crystal piezoelectric material layer away from the second substrate.
  • a layer of tungsten (W), aluminum (Al), copper (Cu) is formed by magnetron sputtering on the surface of the single crystal piezoelectric material layer 11 away from the first electrode 13 side.
  • the first electrode 13 and the second electrode 15 may be made of aluminum (Al) and platinum (Pt).
  • the thickness of the deposited first electrode 13 and the second electrode 15 is determined according to actual production requirements; at the same time, the shape of the electrode may be similar or dissimilar to the substrate or the piezoelectric film, and the specific structure needs to be determined according to actual conditions.
  • the second substrate 14 may be a silicon wafer, and may be a layer of sacrificial material as a temporary support structure. Finally, referring to FIG. 11, part of the material in the second substrate 14 may be removed by etching to form an empty space. Cavity.
  • a molybdenum electrode is first formed on the substrate, and then a piezoelectric film is formed on the molybdenum electrode.
  • the internal stress in the resonator is relatively easily controlled, so that the polycrystalline AlN is based on Mass production is possible. If replaced with other metal electrodes, the internal stress of the resonator is more difficult to control and the production yield is lower.
  • the formed electrode is not limited to the molybdenum electrode, and a plurality of conductive materials may be selected, and the first electrode is formed after the piezoelectric film is prepared, and the first substrate is peeled off.
  • the second electrode is formed on the other side of the piezoelectric film, thereby avoiding the formation of the piezoelectric film directly on the second electrode, so that the electrodes on both sides of the piezoelectric material can select different metal materials according to different process and performance requirements in order to achieve The best price/performance ratio.
  • aluminum has a lower resistivity than molybdenum, which can reduce the parasitic resistance of the resonator and increase the Q of the resonator.
  • FIG. 12 is a schematic structural view of a piezoelectric resonator provided in Embodiment 6.
  • the piezoelectric resonator can It is prepared by the preparation method of any one of the piezoelectric resonators provided by the embodiments of the present disclosure. As shown in FIG. 12, the piezoelectric resonator includes:
  • a polycrystalline piezoelectric material layer 12 formed on a surface of one side of the single crystal piezoelectric material layer 11; a first electrode 13 formed on a surface of the polycrystalline piezoelectric material layer 12 away from the side of the single crystal piezoelectric material layer 11; formed in a single The crystalline piezoelectric material layer 11 is away from the second electrode 15 on the surface of one side of the polycrystalline piezoelectric material layer 12.
  • the material of the single crystal piezoelectric material layer 11 may be single crystal AlN. Due to the high acoustic velocity of AlN, AlN thin film materials can be used to fabricate high frequency resonators (GHz), and the loss of AlN materials is low, high quality factor (Q) values can be achieved, and in complex working environments. Used in.
  • the polycrystalline piezoelectric material layer 12 may be the same as or different from the material of the single crystal piezoelectric material layer 11.
  • the polycrystalline piezoelectric material layer 12 may be made of polycrystalline AlN or lead zirconate titanate piezoelectric ceramics. , polycrystalline zinc oxide, lithium niobate or lithium niobate.
  • LiNbO 3 has a high piezoelectric coupling coefficient (k t 2 ), and the piezoelectric coupling coefficient (k t 2 ) is an important physical quantity to measure the piezoelectric properties of piezoelectric materials, which determines the bandwidth that the filter can achieve.
  • the piezoelectric coupling coefficient (k t 2 ) of LiNbO 3 and PZT is high, and the achievable bandwidth is large; the k t 2 of zinc oxide (ZnO) is 7.5%; the k t 2 of AlN is 6.5%.
  • the quality factor (Q) is an important indicator for describing the filter element.
  • the Q value of the piezoelectric resonator depends on the inherent loss of the piezoelectric film material and the loss of the bulk acoustic wave in the substrate. In this respect, the material loss of AlN and ZnO is superior to that of PZT materials.
  • the single crystal piezoelectric material layer has a thickness of less than 0.6 ⁇ m.
  • the total thickness of the single crystal piezoelectric material layer and the polycrystalline piezoelectric material layer is greater than or equal to 1.5 ⁇ m.
  • the material of the first electrode 13 and the second electrode 15 may be one or a combination of Al, Cu, Ag, Pt, W, Ti, and Mo.
  • Al and Pt can be selected, the main reason is that the resistivity of the Al material is small, and the mechanical properties of the Pt and W electrodes in the AlN resonator are superior.
  • the piezoelectric resonator provided in this embodiment may be applied to the field of communication in which the resonant frequency is a low frequency band.
  • the piezoelectric resonator provided in this embodiment passes through the single crystal piezoelectric material.
  • a polycrystalline piezoelectric material layer is formed on one surface of the layer, which can make the piezoelectric material layer reach a certain thickness in a relatively fast time, shorten the process time, reduce the production cost, realize the resonance frequency of the low frequency band, and ensure the high Q.
  • the value and the high-voltage electrical coupling coefficient (k t 2 ) performance and increase the filter bandwidth, increasing the scope of application.
  • the present disclosure provides a method of fabricating a piezoelectric resonator and a piezoelectric resonator. Since the crystallinity of the single crystal piezoelectric material is high, the lattice starting point of the polycrystalline piezoelectric material deposited on the single crystal piezoelectric material layer The arrangement is more tidy, thereby improving the crystallinity of the polycrystalline piezoelectric material in the polycrystalline piezoelectric material layer and improving the performance of the piezoelectric resonator.

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Abstract

压电谐振器的制备方法和压电谐振器，其中制备方法包括：在第一衬底上形成单晶压电材料层；在单晶压电材料层远离所述第一衬底一侧的表面形成多晶压电材料层。

Description

压电谐振器的制备方法和压电谐振器 技术领域
本公开涉及压电器件领域，例如涉及一种压电谐振器的制备方法和压电谐振器。
背景技术
薄膜体声波谐振器(Film Bulk Acoustic Resonator，FBAR)又称为压电薄膜体声波谐振器，其原理是利用压电薄膜的逆压电效应将输入的高频电信号转化为一定频率的声信号，并产生谐振，其中谐振频率处的声波损耗最小。通过压电谐振技术可以制备更先进的电子元器件，并为通信技术提供更广泛的应用范围。
通常，压电谐振器包括相对设置的两个电极以及位于两个电极之间的压电薄膜。相关技术中常采用单晶氮化铝AlN压电材料或多晶氮化铝AlN压电材料制备压电薄膜，但单晶AlN压电材料的生长或者沉积的速度慢，其内应力不易控制，增加了较多的工艺问题，导致生产成本较高，难以得到厚度较大的压电薄膜，很难制备低频段更高性能的滤波器；而生长多晶AlN压电材料形成的压电薄膜的厚度可以达到较厚的厚度，可以实现低频段谐振器，但多晶AlN结晶质量较差，会使得品质因数Q和压电耦合系数kt 2较低，导致制备的谐振器的性能降低。
发明内容
本公开提供一种压电谐振器的制备方法和压电谐振器，既可以较容易地制备厚度较厚的压电薄膜，易于实现低频段的压电谐振器，且降低了生产成本及工艺难度，又可以提高压电谐振器的性能，且比多晶压电材料的结晶度较高。
第一方面，本公开提供了一种压电谐振器的制备方法，包括：
在第一衬底上形成单晶压电材料层；
在所述单晶压电材料层远离所述第一衬底一侧的表面形成多晶压电材料层。
第二方面，本公开还提供了一种压电谐振器，包括：
单晶压电材料层；
形成于所述单晶压电材料层一侧表面的多晶压电材料层；
形成于所述多晶压电材料层远离所述单晶压电材料层一侧表面的第一电极；
形成于所述单晶压电材料层远离所述多晶压电材料层一侧表面的第二电极。
本公开提供的一种压电谐振器的制备方法和压电谐振器，通过在第一衬底上形成单晶压电材料层，再在单晶压电材料层上形成多晶压电材料层，以此形成由单晶压电材料层和多晶压电材料层组成的压电薄膜，可以通过调整单晶压电材料层和多晶压电材料层的厚度比来优化压电谐振器的综合性价比，可以通过调整压电薄膜的总厚度来实现低频段压电谐振器。在实现低频段压电谐振器的情况下，还可以形成较薄的单晶压电材料层和较厚的多晶压电材料层来降低生产成本及工艺难度；同时，由于单晶压电材料的结晶度高，因此，在单晶压电材料层上沉积的多晶压电材料的晶格起点排列更整齐，进而提高了多晶压电材料层中多晶压电材料的结晶度，提高了压电谐振器的性能。
附图说明
图1是实施例一提供的一种压电谐振器制备方法的流程图；
图2-图3是实施例一提供的制备流程中各步骤对应的压电谐振器的剖面结构示意图；
图4是实施例二提供的一种压电谐振器制备方法的流程图；
图5是实施例三提供的一种压电谐振器制备方法的流程图；
图6是实施例四提供的一种压电谐振器制备方法的流程图；
图7是实施例五提供的一种压电谐振器制备方法的流程图；
图8-图11是实施例五提供的电极制备流程中各步骤对应的压电谐振器的剖面结构示意图；
图12是实施例六提供的一种压电谐振器的结构示意图。
具体实施方式
下面结合附图和实施例对本公开进行说明。此处所描述的具体实施例仅用于解释本公开，而非对本公开的限定。
实施例一
图1为施例一提供的一种压电谐振器制备方法的流程图，图2-图3是实施例一提供的制备流程中每个步骤对应的压电谐振器的剖面结构示意图。本实施例可适用于提高压电谐振器性能的情况。如图1所示，本实施例提供的压电谐振器的制备方法包括：
步骤110、在第一衬底上形成单晶压电材料层。
参考图2，在第一衬底10上形成单晶压电材料层11，其中，单晶压电材料层11的材料可以是单晶AlN，可以通过外延方法形成。示例性的，外延方法可以包括金属有机物化学气相沉积法(MOCVD)又叫金属有机化学气相外延(MOVPE)，可以选择铝的有机物(一般可以是三甲基铝)作为铝源，氨气作为反应的氮源，可以在载流气体氢气输运下，将有机铝源和过剩的氨气输入到真空的反应腔内，在高温作用下，有机铝源与氨气发生反应，生产出高质量的单晶压电材料层11。此外，可选地，单晶压电材料还可以为氧化锌(ZnO)、钽酸锂(LiTaO3)、或铌酸锂(LiNbO3)等，利用上述材料在第一衬底上形成单晶压电材料层11。
步骤120、在单晶压电材料层远离第一衬底一侧的表面形成多晶压电材料层。
参考图3，可以通过沉积方法在单晶压电材料层11远离第一衬底10一侧的表面形成多晶压电材料层12。其中，多晶压电材料层12与单晶压电材料层11的材料可以相同或不同。可选地，多晶压电材料层12的材料可以是多晶AlN，沉积方法可以为射频磁控溅射沉积技术，可以利用高纯铝Al靶(99.99％)，以高纯的氩Ar、氮气N2分别作为溅射气体和反应气体，在制备高质量单晶AlN材料层的基础上，通过对实验参数(例如工作气压、衬底温度、N2流量以及靶基距离等)进行调整，制备多晶AlN薄膜材料。由于在第一衬底10上形成单晶压电材料层11，单晶压电材料层11的结晶度高，可以使单晶压电材料层11表面沉积的多晶压电材料12存在排列更整齐的晶格起点，因此可以使得在第一衬底10上沉积的多晶AlN压电材料的结晶度更高，性能更好。此外，可选地，多晶压电材料还可以为氧化锌(ZnO)、锆钛酸铅压电陶瓷(PZT)、钽酸锂(LiTaO3)或 铌酸锂(LiNbO3)等，可以使用上述材料在制备的单晶压电材料层11上形成多晶压电材料层12。
本施例提供的一种压电谐振器的制备方法，通过在第一衬底上形成单晶压电材料层，再在单晶压电材料层上形成多晶压电材料层，以此形成由单晶压电材料层和多晶压电材料层组成的压电薄膜，可以通过调整单晶压电材料层和多晶压电材料层的厚度比来优化压电谐振器的综合性价比，可以通过调整压电薄膜的总厚度来实现低频段压电谐振器，在实现低频段压电谐振器的情况下，还可以形成较薄的单晶压电材料层和较厚的多晶压电材料层来降低生产成本及工艺难度；同时，由于单晶压电材料的结晶度高，因此，在单晶压电材料层上沉积的多晶压电材料的晶格起点排列更整齐，进而提高了多晶压电材料层中多晶压电材料的结晶度，提高了压电谐振器的性能。
上述技术方案中，可选的，单晶压电材料层11和多晶压电材料层12的总厚度(即压电薄膜的厚度)大于或等于1.5μm，可以满足压电谐振器的谐振频率为100MHz～3GHz(低频段)的要求。
实施例二
图4为实施例二提供的一种压电谐振器制备方法的流程图。本实施例在实施例一的基础上进行优化，其中，步骤110、在第一衬底上形成单晶压电材料层包括：
提供单晶衬底；在该单晶衬底上外延生长单晶AlN，形成单晶AlN压电层。其中，单晶AlN压电层也即为上述单晶压电材料层。
在上述实施例的基础上，可选的，多晶压电材料层与单晶压电材料层的材料相同。在上述实施例的基础上，可选地，在单晶压电材料层远离第一衬底一侧的表面形成多晶压电材料层包括：在单晶AlN压电层远离第一衬底一侧的表面沉积多晶AlN，形成多晶AlN压电层。如图4所示，本实施例的方法包括：
步骤210、提供单晶衬底；
其中，若所制备的单晶压电材料层11的材料为单晶AlN，则所提供的单晶衬底可以是碳化硅SiC、蓝宝石和氮化镓GaN等单晶衬底，因为AlN是一种重要 的III-V族氮化物，具有稳定的纤锌矿结构，使得在上述衬底上制备的AlN薄膜晶格失配度和热失配相对较小，进而使得制备薄膜的缺陷减少，降低晶格失配对薄膜质量的影响。
其中，AlN材料在的高温下依旧能够保持压电性，所以，AlN压电薄膜器件可以适应高温工作环境。良好的化学稳定性也使得AlN压电薄膜能够适应腐蚀性工作环境。AlN材料还具有良好的热传导特性，这使得由AlN制作的声波器件不会因工作产热而降低器件的使用寿命。因此，AlN可做为单晶压电材料层11的材料。
步骤220、在单晶衬底上外延生长单晶AlN，以形成单晶AlN压电层。
其中，单晶衬底上外延生长单晶AlN，单晶AlN的外延生长方法可以为金属有机物化学气相沉积(MOCVD)、分子束外延(MBE)、脉冲激光沉积(PLD)或射频磁控溅射方法。本实施例中，可通过金属有机物化学气相沉积(MOCVD)方法生长单晶AlN。其中，在单晶AlN的生长过程中，以铝的有机物(可以是三甲基铝)作为铝源，氨气作为氮源，在载流气体氢气输运下，将有机铝源和过剩的氨气输入到真空反应腔内，在高温作用下，有机铝源与氨气发生反应，产生单晶AlN薄膜沉积在衬底表面。利用MOCVD方法可以对单晶AlN薄膜的组成、生长厚度及其均匀性进行严格的控制，制备出高质量的单晶AlN薄膜材料，适用于批量生产单晶A1l薄膜。
步骤230、在单晶AlN压电层远离第一衬底一侧的表面沉积多晶AlN，以形成多晶AlN压电层。
其中，在单晶AlN压电层远离第一衬底10一侧的表面沉积多晶AlN，形成多晶AlN压电层，其中沉积的方法可以是射频磁控溅射沉积方法，利用高纯Al靶(99.99％)，以高纯的Ar、N2分别作为溅射气体和反应气体，在制备高质量单晶AlN材料层的基础上，通过对实验参数(例如：工作气压、衬底温度，N2流量以及靶基距离等)调整，制备多晶AlN薄膜材料。由于在第一衬底10上形成单晶压电材料层11，单晶压电材料层11的结晶度高，可以使其表面沉积的多晶压电材料存在排列更整齐的晶格起点，因此可以使得在第一衬底10上沉积的多晶AlN压电材料的结晶度更高，性能更好。
本实施例中，可选的，单晶AlN压电层的厚度小于0.6μm。单晶AlN压电层生长到0.6μm以上时，生长工艺时间较长，工艺问题较多，受工艺和生产要求的限制，生长更厚的单晶AlN压电层会大大增加生产成本，降低生产良率，因此，仅通过单晶AlN压电层很难制备高性能的低频段(比如1GHz以下)压电谐振器。本实施例单晶AlN压电层的厚度小于0.6μm，通过沉积多晶AlN压电层来增加压电薄膜的厚度，例如，压电谐振器的谐振频率要求做到2GHz，若对应压电薄膜的厚度为1.5μm，则其中单晶AlN压电层的厚度可以为0.5μm甚至更小，多晶AlN压电层的厚度则可以为1μm，由此可以节省制备单晶AlN压电层的时间，使得整体制备时间缩短，减少工艺问题，实现低频段及高性能的压电谐振器。
本实施例提供的一种压电谐振器的制备方法，在单晶衬底上外延生长单晶AlN，可以减小AlN晶格失配度和热失配，利于单晶AlN结晶，降低晶格失配对压电薄膜质量的影响；在单晶AlN压电层上沉积多晶AlN压电层，与单纯用多晶AlN实现的谐振器和滤波器相比(本领域主流大规模量产的产品)，可以降低损耗，实现高Q值和低插损。
实施例三
图5为实施例三提供的一种压电谐振器制备方法的流程图。本实施例与上述实施例二不同的是：多晶压电材料层与单晶压电材料层的材料不同；相应的，可选地，在单晶压电材料层远离第一衬底一侧的表面形成多晶压电材料层包括：采用沉积法在单晶AlN压电层远离第一衬底一侧的表面沉积多晶氧化锌，形成ZnO压电层。如图5所示，本实施例的方法包括：
步骤310、提供单晶衬底；
步骤320、在单晶衬底上外延生长单晶AlN，以形成单晶AlN压电层。
步骤330、采用沉积法在单晶AlN压电层远离第一衬底一侧的表面沉积多晶氧化锌，以形成ZnO压电层。
其中，ZnO薄膜具有较高的压电性(压电常数d33≈12pm/V)，其结构也为纤锌矿结构，可以在单晶AlN薄膜的基础上，形成良好的晶格匹配，降低晶格失 配对多晶ZnO薄膜质量的影响。
可选地，在单晶AlN压电层远离第一衬底10一侧的表面沉积多晶氧化锌，形成多晶ZnO压电层，沉积的方法可以是射频磁控溅射沉积方法，利用ZnO陶瓷靶(99.9％)，以高纯的O2、Ar分别作为反应气体和保护气体，在制备高质量单晶AlN材料层的基础上，通过对实验参数(如工作气压、气体流量、衬底温度、沉积时间以及靶基距离等)进行调整，制备多晶ZnO压电层。由于在第一衬底10上形成单晶压电材料层11，单晶压电材料层11的结晶度高，可以使其表面沉积的多晶压电材料存在排列更整齐的晶格起点，因此可以使得在第一衬底上沉积的多晶ZnO压电材料的结晶度更高，性能更好。
本实施例提供的一种压电谐振器的制备方法，在单晶AlN压电层上沉积多晶ZnO，相对于多晶AlN压电层，可以提高压电谐振器的压电耦合系数kt 2，进而提高压电谐振器的性能。
实施例四
图6为实施例四提供的一种压电谐振器制备方法的流程示意图。本实施例与上述实施例二不同的是：多晶压电材料层与单晶压电材料层的材料不同；相应的，在单晶压电材料层远离第一衬底一侧的表面形成多晶压电材料层包括：采用沉积法在单晶AlN压电层远离第一衬底一侧的表面沉积锆钛酸铅压电陶瓷，形成PZT压电层。如图6所示，本实施例的方法包括：
步骤410、提供单晶衬底；
步骤420、在单晶衬底上外延生长单晶AlN，以形成单晶AlN压电层。
步骤430、采用沉积法在单晶AlN压电层远离第一衬底一侧的表面沉积锆钛酸铅压电陶瓷，以形成PZT压电层。
其中，PZT薄膜具备力-电耦合性能，其压电耦合系数kt 2较高，是制作宽带宽滤波器的较优材料。可选地，在单晶AlN压电层远离第一衬底10一侧的表面沉积多晶锆钛酸铅压电陶瓷，形成多晶PZT压电层，沉积的方法可以是脉冲激光沉积方法，比如以锆钛比Zr/Ti＝52/48的PZT压电陶瓷为靶材，在制备有单晶AlN压电层上，使用脉冲激光沉积法制备PZT薄膜。其中，使用氟化氪KrF 脉冲激光器，实验时先进行抽真空，再通入氧气达到一定压强。经制备有高质量单晶AlN压电层的衬底进行加热到一定温度，使KrF脉冲激光以45℃角入射到PZT靶材，使PZT的原子从靶材上射出沉积到衬底上。随后缓慢冷却至室温使其薄膜晶化，从而制备出PZT薄膜。通过对实验参数(如工作气压、基底温度、沉积时间以及靶基距离等)进行调整，制备PZT压电层。
本实施例提供的一种压电谐振器的制备方法，在单晶AlN压电层上沉积PZT压电层，相对于多晶AlN压电层，可以提高压电谐振器的压电耦合系数kt 2，进而提高压电谐振器的性能。
实施例五
图7是实施例五提供的一种压电谐振器制备方法的流程图；图8-图11是实施例五提供的电极制备流程中每个步骤对应的压电谐振器的剖面结构示意图。在上述实施例的基础上，本实施例在单晶压电材料层远离第一衬底一侧的表面形成多晶压电材料层之后，还可以包括：在多晶压电材料层远离第一衬底一侧的表面形成第一电极；将带有第一电极的压电谐振器通过第一电极压合至第二衬底，并利用薄膜转移工艺将第一衬底剥离掉；在单晶压电材料层远离第二衬底一侧的表面形成第二电极。如图7所示，本实施例的方法包括：
步骤510、在第一衬底上形成单晶压电材料层。
步骤520、在单晶压电材料层远离第一衬底一侧的表面形成多晶压电材料层。
步骤530、在多晶压电材料层远离第一衬底一侧的表面形成第一电极。
参考图8，在多晶压电材料层12远离第一衬底10一侧的表面形成第一电极13，其形成的方法可以是磁控溅射方法，可以在多晶压电材料层12上沉积一层钨(W)、铝(Al)、铜(Cu)、铂(Pt)、银(Ag)、钛(Ti)和钼(Mo)中的一种或多种组合，其中第一电极13可以与衬底具有类似的形状。
步骤540、将带有第一电极的压电谐振器通过第一电极压合至第二衬底，并利用薄膜转移工艺将第一衬底剥离掉。
参考图9，示例性的，首先，将第一衬底10、单晶压电材料层11、多晶压 电材料层12及第一电极13翻转并将第一电极13机械压合至第二衬底14上，使第一电极13远离单晶压电材料层11的表面与第二衬底14表面键合形成牢固结构。其次，通过激光剥离或等离子体剥离技术将单晶压电材料层11从第一衬底10上剥离掉，激光剥离或等离子体剥离技术的剥离率较高，同时可以尽可能地避免剥离过程中的薄膜及衬底片的破裂。
步骤550、在单晶压电材料层远离第二衬底一侧的表面形成第二电极。
参考图10，基于上述方案，在单晶压电材料层11远离第一电极13一侧的表面上通过磁控溅射技术形成一层由钨(W)、铝(Al)、铜(Cu)、银(Ag)、铂(Pt)和钼(Mo)等至少一种材料构成的电极结构，该电极结构为第二电极15。可选地，第一电极13和第二电极15材料可以为铝(Al)和铂(Pt)。其中，沉积的第一电极13和第二电极15的厚度根据实际生产要求的情况而定；同时，电极形状可以与衬底或压电薄膜相似或不相似，具体结构需要根据实际情况进行确定。其中，第二衬底14可以是硅片，可以为一层牺牲材料作为临时的支撑结构，最后，参考图11，可以通过刻蚀技术，去除掉第二衬底14中的部分材料，形成空腔。
在制备多晶压电谐振器时，先在衬底上形成一个钼电极，再在该钼电极上形成压电薄膜，此时，谐振器中的内应力相对比较容易控制，使得基于多晶AlN的大规模量产成为可能。如果换成其他金属电极，谐振器的内应力比较难控制，生产良率较低。
本实施例提供的一种压电谐振器的制备方法，形成的电极不局限于钼电极，可以选择多种导电材料，且在制备压电薄膜之后形成第一电极，在将第一衬底剥离后，在压电薄膜的另一面形成第二电极，避免了直接在第二电极上形成压电薄膜，使得压电材料两面上的电极可以根据不同的工艺和性能需求选择不同的金属材料以期达到最佳的性价比。比如，铝就比钼有着更小的电阻率，可以降低谐振器的寄生电阻，提高谐振器的Q值。
实施例六
图12是实施例六提供的一种压电谐振器的结构示意图。该压电谐振器可使 用本公开实施例提供的任一种压电谐振器的制备方法制备，如图12所示，该压电谐振器包括：
形成于单晶压电材料层11一侧表面的多晶压电材料层12；形成于多晶压电材料层12远离单晶压电材料层11一侧表面的第一电极13；形成于单晶压电材料层11远离多晶压电材料层12一侧表面的第二电极15。
其中，单晶压电材料层11的材料可以为单晶AlN。由于AlN的声波速较高，使得AlN薄膜材料可以被用来制作高频谐振器(GHz)，并且AlN材料的损耗较低，可以实现高品质因数(Q)值，而且能够在复杂的工作环境中使用。
可选地，多晶压电材料层12可以与单晶压电材料层11的材料相同或不同，例如：多晶压电材料层12的材料可以为多晶AlN、锆钛酸铅压电陶瓷、多晶氧化锌、钽酸锂或铌酸锂等。其中，LiNbO3的压电耦合系数(kt 2)较高，压电耦合系数(kt 2)是衡量压电材料压电性能强弱的重要物理量，决定了滤波器可实现的带宽。LiNbO3和PZT的压电耦合系数(kt 2)较高，可实现的带宽大；氧化锌(ZnO)的kt 2为7.5％；AlN的kt 2为6.5％。另外，品质因数(Q)是描述滤波器件的一个重要的指标，压电谐振器的Q值取决于压电薄膜材料的固有损耗以及体声波在衬底中的损耗。在此方面，AlN和ZnO的材料损耗要优于PZT材料。
可选地，所述单晶压电材料层的厚度小于0.6μm。
可选地，单晶压电材料层和多晶压电材料层总厚度大于或等于1.5μm。
可选地，第一电极13与第二电极15的材料可以为Al、Cu、Ag、Pt、W、Ti和Mo中的一种或者多种组合。可以选择Al和Pt，主要原因是Al材料的电阻率较小，Pt和W电极在AlN谐振器中的力学性质较优。
未在本实施例中详尽描述的内容请参考上述方法实施例，此处不再赘述。
本实施例提供的压电谐振器可以为应用于谐振频率为低频段的通信领域，相比相关技术来说，本实施例提供的一种压电谐振器，通过在所述单晶压电材料层一侧表面上形成多晶压电材料层，可以使得压电材料层在较快时间内达到一定厚度，缩短了工艺时间，降低了生产成本，可以实现低频段的谐振频率，同时保证高Q值和高压电耦合系数(kt 2)的性能，并提高了滤波器带宽，增加了应用范围。
工业实用性
本公开提供一种压电谐振器的制备方法和压电谐振器，由于单晶压电材料的结晶度高，因此，在单晶压电材料层上沉积的多晶压电材料的晶格起点排列更整齐，进而提高了多晶压电材料层中多晶压电材料的结晶度，提高了压电谐振器的性能。

Claims (16)

  1. 一种压电谐振器的制备方法，包括：
    在第一衬底上形成单晶压电材料层；
    在所述单晶压电材料层远离所述第一衬底一侧的表面形成多晶压电材料层。
  2. 根据权利要求1所述的制备方法，其中，在第一衬底上形成单晶压电材料层的步骤包括：
    提供单晶衬底；
    在所述单晶衬底上外延生长单晶氮化铝AlN，以形成单晶AlN压电层。
  3. 根据权利要求2所述的制备方法，其中，所述多晶压电材料层与所述单晶压电材料层的材料相同。
  4. 根据权利要求3所述的制备方法，其中，在所述单晶压电材料层远离所述第一衬底一侧的表面形成多晶压电材料层的步骤包括：
    在所述单晶AlN压电层远离所述第一衬底一侧的表面沉积多晶AlN，以形成多晶AlN压电层。
  5. 根据权利要求2所述的制备方法，其中，所述多晶压电材料层与所述单晶压电材料层的材料不同。
  6. 根据权利要求5所述的制备方法，其中，在所述单晶压电材料层远离所述第一衬底一侧的表面形成多晶压电材料层的步骤包括：
    采用沉积法在所述单晶AlN压电层远离所述第一衬底一侧的表面沉积锆钛酸铅压电陶瓷PZT、多晶氧化锌ZnO、钽酸锂LiTaO3或铌酸锂LiNbO3，以形成PZT压电层、ZnO压电层、LiTaO3压电层或LiNbO3压电层。
  7. 根据权利要求2-6任一项所述的制备方法，其中，所述单晶AlN压电层的厚度小于0.6μm。
  8. 根据权利要求1所述的制备方法，其中，所述单晶压电材料层和所述多晶压电材料层的总厚度大于或等于1.5μm。
  9. 根据权利要求1所述的制备方法，其中，在所述单晶压电材料层远离所述第一衬底一侧的表面形成多晶压电材料层的步骤之后，还包括：
    在所述多晶压电材料层远离所述第一衬底一侧的表面形成第一电极；
    将所述第一电极与第二衬底压合，并利用薄膜转移工艺将所述第一衬底剥离掉；
    在所述单晶压电材料层远离所述第二衬底一侧的表面形成第二电极。
  10. 根据权利要求9所述的制备方法，其中，所述第一电极和所述第二电极中的至少一种电极的材料为铝Al、铜Cu、银Ag、钨W、铂Pt、钛Ti和钼Mo中的一种或者多种组合。
  11. 一种压电谐振器，包括：
    单晶压电材料层；
    形成于所述单晶压电材料层一侧表面的多晶压电材料层；
    形成于所述多晶压电材料层远离所述单晶压电材料层一侧表面的第一电极；
    形成于所述单晶压电材料层远离所述多晶压电材料层一侧表面的第二电极。
  12. 根据权利要求11所述的压电谐振器，其中，所述单晶压电材料层的材料为单晶AlN。
  13. 根据权利要求12所述的压电谐振器，其中，所述多晶压电材料层的材料为多晶氮化铝AlN、锆钛酸铅压电陶瓷、多晶氧化锌、钽酸锂或铌酸锂。
  14. 根据权利要求12或13所述的压电谐振器，其中，所述单晶压电材料层的厚度小于0.6μm。
  15. 根据权利要求11所述的压电谐振器，其中，所述单晶压电材料层和所述多晶压电材料层的总厚度大于或等于1.5μm。
  16. 根据权利要求11所述的压电谐振器，其中，所述第一电极和所述第二电极中的至少一种电极的材料为铝Al、铜Cu、银Ag、钨W、铂Pt、钛Ti和钼Mo中的一种或多种组合。
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CN105703733A (zh) * 2016-01-18 2016-06-22 佛山市艾佛光通科技有限公司 一种固态装配型薄膜体声波谐振器的制备方法

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