WO2024002237A1 - 声表面波谐振器、滤波器、通讯设备 - Google Patents

声表面波谐振器、滤波器、通讯设备 Download PDF

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Publication number
WO2024002237A1
WO2024002237A1 PCT/CN2023/103820 CN2023103820W WO2024002237A1 WO 2024002237 A1 WO2024002237 A1 WO 2024002237A1 CN 2023103820 W CN2023103820 W CN 2023103820W WO 2024002237 A1 WO2024002237 A1 WO 2024002237A1
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Prior art keywords
surface acoustic
acoustic wave
wave resonator
electrode
piezoelectric layer
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PCT/CN2023/103820
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English (en)
French (fr)
Inventor
鲍景富
何艺雯
黄裕霖
李昕熠
高宗智
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华为技术有限公司
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Publication of WO2024002237A1 publication Critical patent/WO2024002237A1/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
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, 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
    • 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
    • H03H9/02614—Treatment of substrates, e.g. curved, spherical, cylindrical substrates ensuring closed round-about circuits for the acoustical 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
    • H03H9/02535—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
    • H03H9/46—Filters
    • H03H9/64—Filters using surface acoustic waves

Definitions

  • the present application relates to the field of resonator technology, and in particular to a surface acoustic wave resonator, a filter with a surface acoustic wave resonator, and a communication device including a surface acoustic wave filter.
  • surface acoustic wave resonators surface acoustic wave, SAW
  • SAW surface acoustic wave
  • the surface acoustic wave resonator SAW uses the piezoelectric effect to achieve electro-acoustic-electric energy conversion, and has the advantages of small structural size.
  • RF filters through the series and parallel connection of the surface acoustic wave resonator SAW, it can be realized with low insertion loss and high rectangularity coefficient.
  • the existence of transverse modes or other spurious modes will reduce the quality factor (also called Q factor) and may affect the flatness of the filter band, that is, reduce the operation of the filter. performance.
  • Q factor quality factor
  • Embodiments of the present application provide a surface acoustic wave resonator, a filter and a communication device.
  • the present application provides a surface acoustic wave resonator, which can be applied in a filter.
  • the surface acoustic wave resonator may include: a substrate, a piezoelectric layer and an electrode.
  • the piezoelectric layer is arranged on the substrate.
  • the electrode is arranged on a side of the piezoelectric layer away from the substrate.
  • the electrode may include applying a voltage to the piezoelectric layer.
  • the first electrode and the second electrode wherein, the material of the substrate is a tetragonal crystal system material; the first slowness curve synthesized by the material of the piezoelectric layer and the electrode material, and the second slowness curve of the tetragonal crystal system material,
  • the concave and convex characteristics in the wave propagation direction of this surface acoustic wave resonator are opposite.
  • a base material of tetragonal crystal system is used, and the characteristics of the first slowness curve synthesized from the material of the piezoelectric layer and the material of the electrode are consistent with those of the tetragonal crystal system material.
  • the characteristics of the second slowness curve are opposite. In this case, the characteristics of the first slowness curve synthesized by the piezoelectric layer material and the electrode material and the second slowness curve of the tetragonal crystal material cancel each other out, which will make the final surface acoustic wave resonator in the surface acoustic wave
  • the slowness curve in the wave propagation direction is flat.
  • the surface acoustic wave resonator provided in this application can not only achieve the above-mentioned flat slowness curve, but also improve the temperature compensation coefficient (temperature coefficient of frequency, TCV) and improve the frequency and temperature stability of the surface acoustic wave resonator. to further optimize the working performance of the resonator.
  • TCV temperature coefficient of frequency
  • the basic relationship between the Euler angle ⁇ and the electromechanical coupling coefficient is: the smaller the Euler angle ⁇ , the greater the electromechanical coupling coefficient, and in turn, the better the performance of the resonator. Therefore, when the Euler angle ⁇ of the piezoelectric material in this application is selected: 0° ⁇ 40°, the electromechanical coupling coefficient of the resonator will be increased.
  • the surface acoustic wave resonator provided in this application not only has a flat slow curve, suppresses the generation of transverse modes, but can also improve the electromechanical coupling coefficient and frequency-temperature stability, so that the surface acoustic wave resonator can work Better performance.
  • the Euler angle ⁇ of the material of the piezoelectric layer ranges from: 0° ⁇ 20°.
  • the temperature characteristics of the tetragonal crystal material are opposite to the temperature characteristics of the material of the piezoelectric layer.
  • the tetragonal crystal system material has a positive temperature coefficient and the piezoelectric layer material has a negative temperature coefficient. Then, the interaction between the tetragonal crystal system material and the piezoelectric layer material can reduce the sensitivity of the resonator performance to temperature to improve Frequency temperature stability of the resonator.
  • the sound wave propagation speed of the tetragonal crystal material is greater than the sound wave propagation speed of the material of the piezoelectric layer.
  • the substrate can reflect the energy leaked from the upper piezoelectric layer, thereby improving the quality factor Q value of the resonator.
  • the tetragonal crystal material of the substrate includes at least one of lithium tetraborate, quartz, and tellurium oxide.
  • the piezoelectric layer includes at least one of lithium tantalate, lithium niobate, aluminum nitride, and zinc oxide.
  • other piezoelectric materials can also be selected.
  • the substrate is lithium tetraborate
  • the surface acoustic wave resonator further includes a dielectric layer, and the dielectric layer is disposed between the substrate and the piezoelectric layer.
  • a dielectric layer can be stacked between the substrate and the piezoelectric layer. By adding a dielectric layer, the energy leakage along the thickness direction of the surface acoustic wave resonator can be further reduced, and the quality factor can be further improved.
  • the surface acoustic wave resonator includes not only a substrate and a piezoelectric layer, but also a dielectric layer formed between the substrate and the piezoelectric layer, the value range of the Euler angle ⁇ of the piezoelectric layer It can be 10° ⁇ 50°.
  • the value range of the Euler angle ⁇ of the piezoelectric layer can be: 10° ⁇ 30°.
  • the electrodes include a plurality of first electrodes and a plurality of second electrodes, and the plurality of first electrodes and the plurality of second electrodes are alternately arranged with a period P1; the thickness t of the dielectric layer is less than or equal to P1.
  • the thickness of the dielectric layer is less than or equal to P1.
  • the frequency temperature stability and electromechanical coupling of the resonator device can be further improved. coefficient.
  • t kP1
  • the value range of k is: 0.1 ⁇ k ⁇ 0.5.
  • the value range of k is: 0.1 ⁇ k ⁇ 0.3.
  • a plurality of first electrodes and a plurality of second electrodes are alternately arranged at equal intervals along a first direction, and the first direction is a direction perpendicular to the extension direction of the first electrodes and the second electrodes.
  • the dielectric layer includes at least one of SiO 2 , SiOF, SiOC, and Ta 2 O 5 .
  • Dielectric materials such as those given in the above examples are all positive temperature coefficient dielectric materials. Of course, other positive temperature coefficient dielectric materials can also be selected.
  • the thickness of at least one end of the electrode is greater than the thickness of a middle portion of the electrode between the two ends.
  • the thickness of the electrode end can be designed to be larger than the thickness of the middle part of the electrode.
  • the transverse mode can be completely suppressed, or other modes can be completely suppressed. Stray modes make the quality factor of the surface acoustic wave resonator better.
  • the width of at least one end of the electrode along the first direction is greater than the width of the middle portion of the electrode along the second direction, and the first direction is opposite to the extension direction of the first electrode and the second electrode. vertical direction.
  • the transverse mode or other stray modes can be further suppressed, and the performance of the resonator can be further optimized.
  • the present application also provides a filter.
  • the filter includes a plurality of electrically connected surface acoustic wave resonators, and at least one surface acoustic wave resonator among the plurality of surface acoustic wave resonators is any one of the above implementation methods. surface acoustic wave resonators.
  • the suppression of the transverse mode is enhanced through the surface acoustic wave resonator, thereby achieving low insertion loss.
  • RF filter with high rectangular coefficient since the surface acoustic wave resonator in any of the above implementations can be used, the suppression of the transverse mode is enhanced through the surface acoustic wave resonator, thereby achieving low insertion loss. , RF filter with high rectangular coefficient.
  • the filter can be a SAW ladder filter, a SAW grid filter, a SAW DMS filter, and their hybrid structure;
  • the present application also provides a communication device, which includes an amplifier and the filter in any of the above implementations, and the filter is electrically connected to the amplifier.
  • the communication device provided by the embodiment of the present application includes the filter in any of the above implementations. Therefore, the communication device provided by the embodiment of the present application and the surface acoustic wave resonator of the above technical solution can solve the same technical problems and achieve the same expectations. Effect.
  • Figure 1 is a partial structural diagram of communication equipment
  • Figure 2 is a partial structural diagram of the communication equipment
  • Figure 3 is a partial structural diagram of a filter in communication equipment
  • Figure 4 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present application.
  • Figure 5 shows the slowness curves of various piezoelectric materials with different Euler angles given in the embodiment of the present application
  • Figure 6 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present application.
  • Figure 7 is a schematic diagram of a wafer arranged in the X-Y plane according to an embodiment of the present application.
  • Figure 8 is a slowness curve of a piezoelectric layer material given in an embodiment of the present application.
  • Figure 9 is a slowness curve of a base material given in an embodiment of the present application.
  • Figure 10 is a slowness curve of a piezoelectric layer material, a base material and a surface acoustic wave resonator according to an embodiment of the present application;
  • Figure 11 shows the electromechanical coupling coefficients of various piezoelectric materials with different Euler angles according to embodiments of the present application
  • Figure 12 is the admittance curve of the surface acoustic wave resonator given in the embodiment of the present application and the surface acoustic wave resonator in related technologies;
  • Figure 13 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present application.
  • Figure 14 is the M-direction view of Figure 13;
  • Figure 15 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present application.
  • Figure 16 is a cross-sectional view along line A-A of Figure 14;
  • Figure 17 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present application.
  • Figure 18 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present application.
  • Figure 19 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present application.
  • Figure 20 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present application.
  • Figure 21 is a schematic structural diagram of a surface acoustic wave resonator according to an embodiment of the present application.
  • Figure 22 is the quality factor curve of various surface acoustic wave resonators given in the embodiment of the present application.
  • Figure 23 is the slowness curve of various surface acoustic wave resonators given in the embodiment of the present application.
  • Figure 24 shows the admittance curves of various surface acoustic wave resonators given in the embodiments of the present application.
  • Electromechanical coupling coefficient K 2 It is a key parameter of the resonator.
  • the electromechanical coupling coefficient K 2 can reflect the conversion efficiency between mechanical energy and electrical energy.
  • the electromechanical coupling coefficient K 2 of the resonator determines the difference between the series and parallel resonant frequencies of the resonator. When resonators are used in filter designs, this difference directly determines the filter bandwidth. It can be considered that the larger the electromechanical coupling coefficient K2 , the higher the conversion efficiency of the resonator and the better its performance.
  • Quality factor Q represents the energy utilization rate of the device, that is, the ratio of the total energy received by the device to the energy dissipated within a vibration cycle.
  • the electromechanical coupling coefficient K 2 and the quality factor Q value of the resonator constituting the filter are important parameters.
  • the Euler angle representation is a crystallographic direction that represents the normal line of the wafer surface, and is related to the surface acoustic wave resonator SAW The propagation direction coincides with the datum direction method. This Euler angle may also be called a tangent angle.
  • Slowness characteristics are usually characterized by slowness curves. Slowness characteristics are physical parameters that measure the propagation of waves in a medium. Slowness is the reciprocal of speed. Therefore, the propagation time of a wave is the distance times the slowness of the medium.
  • Tetragonal crystal system The Bravais lattice has seven major crystal systems on the three-dimensional plane, namely triclinic system, monoclinic system, orthorhombic system, tetragonal system, cubic system, trigonal system and hexagonal system. Tie.
  • the embodiment of the present application provides a communication device.
  • the communication device includes but is not limited to radio frequency front-end, filter amplification module and other products. It may also include mobile phones, tablet computers (pads), smart wearable products (for example, smart watches, Smart bracelets), virtual reality (VR) equipment, augmented reality (AR), drones and other terminal equipment.
  • the embodiments of this application do not place any special restrictions on the specific form of the above communication equipment.
  • the communication device 100 may include a filter 200.
  • the filter 200 may effectively filter out a specific frequency point in the signal or frequencies other than the frequency point to obtain a specific frequency signal, or a signal after eliminating a specific frequency, to improve the working performance of the communication device 100 .
  • FIG. 2 shows a partial circuit diagram in some communication devices 100 .
  • the communication device 100 includes a receiver (Receiver) 600, a transmitter (Transmitter) 700, an antenna (Antenna) 500 and a baseband chip 800.
  • the antenna 500 is electrically connected to the receiver 600 and the transmitter 700 respectively through the switch 900, and the receiver 600 and the transmitter 700 are electrically connected to the baseband chip 800 respectively.
  • the receiver (Receiver) 600 shown in Figure 2 it includes a filter (Filter) 601 and a filter (Filter) 603.
  • a low-noise amplifier 602 is electrically connected between the filter 601 and the filter 603.
  • the filter 603 passes
  • the mixer (Mixer) 604 is electrically connected to the buffer (Buffer) 605, and the buffer 605 is electrically connected to the voltage controlled oscillator 606.
  • Figure 2 is only an exemplary receiver, and electronic components can be added or reduced based on this circuit structure.
  • Transmitter 700 In the transmitter (Transmitter) 700 shown in Figure 2, it includes a power amplifier (PA) 702.
  • the power amplifier 702 is electrically connected to the filter 701 and the driver (Driver) 703 respectively.
  • the driver (Driver) 703 is connected to the voltage control unit.
  • Oscillator 704 is electrically connected.
  • Figure 2 is only an exemplary transmitter, and electronic components can be added or reduced based on this circuit structure.
  • the filter can effectively filter out the frequency point of a specific frequency amplified by the power amplifier or the frequencies outside the frequency point, or the filter can effectively filter out the noise of the low-noise amplifier. messages are filtered.
  • the filter 200 may include a plurality of series resonators 300 , or a plurality of parallel resonators 300 , or a combination of series and parallel resonators 300 .
  • the filter involved in this application may be a SAW ladder filter, a SAW grid filter, etc., or a combination of these structures.
  • At least one of the plurality of resonators included in the filter 200 may be a surface acoustic wave resonator (surface acoustic wave,
  • the main working principle of surface acoustic wave resonator SAW is to use the piezoelectric characteristics of piezoelectricity and use input and output transducers.
  • Transducer converts the input signal of the radio wave into mechanical energy. After processing, the mechanical energy is converted into an electrical signal to achieve the goal of filtering unnecessary signals and noise and improving the quality of reception.
  • FIG. 4 shows a schematic structural diagram of a surface acoustic wave resonator SAW 300A.
  • the surface acoustic wave resonator SAW 300A mainly includes a substrate 301, a piezoelectric layer 302 and an electrode 303.
  • the piezoelectric layer 302 is stacked on the substrate 301
  • the electrode 303 is stacked on a side of the piezoelectric layer 302 away from the substrate 301 , that is, the electrode 303 is stacked on the piezoelectric layer 302 .
  • a voltage can be applied to the piezoelectric layer 302 through the electrode 303, so that the piezoelectric layer 302 uses the piezoelectric effect to generate conversion between electrical energy and mechanical energy.
  • other layer structures such as dielectric layers or other functional layer structures, can be stacked between the piezoelectric layer 302 and the substrate 301 .
  • the main factors affecting the quality factor Q include whether there is a transverse mode in the passband of the surface acoustic wave resonator SAW, or other spurious modes. The more obviously the transverse mode is suppressed, the better the quality factor Q is.
  • the slowness characteristics of the material when characterizing the transverse mode, the slowness characteristics of the material can be used, that is, the flatness of the slowness curve can be measured.
  • the slowness curves corresponding to multiple piezoelectric materials (such as lithium tantalate) with different Euler angles (also called cut angles) are given. They are: curve 1 represents the slowness curve of the piezoelectric material with an Euler angle of 20°, curve 2 represents the slowness curve of the piezoelectric material with an Euler angle of 25°, and curve 3 represents the Euler slowness curve.
  • Curve 4 represents the slowness curve of a piezoelectric material with an Euler angle of 35°.
  • Curve 5 represents the slowness curve of a piezoelectric material with a Euler angle of 40°.
  • Curve 6 represents the slowness curve of the piezoelectric material with a Euler angle of 60°.
  • the slowness curves at low cutting angles are relatively convex.
  • the curve 1 when the cutting angle is 20°
  • the curve 2 when the cutting angle is 25°
  • the curve 3 when the cutting angle is 30°
  • curve 4 when the cutting angle is 35°.
  • the quality factor Q of the wave resonator SAW 300A is also poor, and the performance of the surface acoustic wave resonator SAW 300A is also poor.
  • the embodiments of this application provide some surface acoustic wave resonators SAW 300A.
  • the slowness curves of these surface acoustic wave resonators SAW 300A are relatively flat and the quality factor Q is high.
  • the specific structures that can be realized are as follows.
  • FIG 6 is a three-dimensional structural diagram of the surface acoustic wave resonator SAW 300A given in the embodiment of the present application.
  • the SAW 300A also includes a substrate 301, a piezoelectric layer 302 stacked on the substrate 301, and an electrode 303 stacked on the piezoelectric layer 302.
  • the material of the substrate 301 is a tetragonal crystal system material.
  • the wave of the surface acoustic wave resonator is The concave and convex characteristics are opposite in the direction of propagation.
  • the stacking direction of the piezoelectric layer 302 and the substrate 301 can be called the Z direction.
  • the piezoelectric layer 302 and the substrate 301 are respectively located perpendicular to the Z direction. in the X-Y plane.
  • the propagation direction of the wave in the X-Y plane is the wave propagation direction of the surface acoustic wave resonator.
  • each figure in Figures 8 and 9 shows three curves, and they are curves in the range of 0° to 360°, that is, in the X-Y plane, 0° to a slowness curve in the range of 360°.
  • the three curves in Figure 8 are slowness curves of the material of the piezoelectric layer 302 in the wave propagation direction when the surface acoustic wave resonator is in different modes.
  • the slowness curves of the material of the substrate 301 in the wave propagation direction when the surface acoustic wave resonator is in different modes are slowness curves of the material of the substrate 301 in the wave propagation direction when the surface acoustic wave resonator is in different modes.
  • the slowness curve of the surface acoustic wave resonator when it is in one of the modes, for example, the slowness curve of the material of the piezoelectric layer 302 (such as the curve S01), the slowness curve of the material of the substrate 301 (such as the curve S02).
  • a dotted box is used to illustrate The slowness curve S1 of the material of the piezoelectric layer 302 near 0° (near 0° here can be understood as 0 degrees to 30°, and 330° to 360°) is also shown in a dotted line box in Figure 9
  • the slowness curve S2 of the material of the substrate 301 near 0° (the vicinity of 0° can be understood as 0° to 30°, and 330° to 360°).
  • Figure 7 shows a schematic diagram of a wafer arranged in the X-Y plane.
  • the reference orientation flat, OF
  • the wave propagation direction is that position 5 points to position 4, and position 5 points to position 2. Then, rotate the OF direction 90° counterclockwise, and the range is 0° to 360°. 0° within.
  • the slowness curve S1 of the material of the piezoelectric layer 302 is slightly concave near 0°.
  • the slowness curve of the material of the electrode 303 has a circular structure. Then, after the slowness curve S1 of the material of the piezoelectric layer 302 shown in Figure 8 is combined with the slowness curve of the material of the electrode 302, the figure will be obtained.
  • the slowness curve S3 of the material slowness curve of the piezoelectric layer 302 and the slowness curve of the electrode 303 shown in 10 (the slowness curve S3 may also be called the first slowness curve, the slowness curve S3 Curve S3 can also be considered as the slowness curve of the surface acoustic wave resonator in the prior art when the tetragonal crystal material substrate is not used).
  • the slowness curve S2 of the material of the substrate 301 (the slowness curve S2 may also be called the second slowness curve) has a deeper depression.
  • the slowness curve S2 of the material of the substrate 301 shown in FIG. 10 and the slowness curve S3 of the slowness curve of the material of the piezoelectric layer 302 and the slowness curve of the material of the electrode 303 shown in FIG.
  • the slowness curve S4 of the surface acoustic wave resonator 300A shown in Figure 10 will be obtained, that is, the concave and convex characteristics of the first slowness curve and the second slowness curve are On the contrary, they may cancel each other out to achieve flattening of the slowness curve of the surface acoustic wave resonator 300A.
  • the slowness curve of the surface acoustic wave resonator is shown as the slowness curve S3 in Figure 10.
  • the slowness curve S3 is By interacting with the slowness curve S2 of the material of the substrate 301 in Figure 10, the slowness curve S4 of the surface acoustic wave resonator 300a in Figure 10 can be obtained. That is to say, in the embodiments given in this application, by changing the material of the substrate 301, the slowness characteristics of the substrate 301 can interact with the slowness characteristics of the piezoelectric layer and the electrode, so that a surface acoustic wave resonator is formed.
  • the slowness curve S4 of SAW 300A tends to be flat to enhance the suppression of transverse modes and improve the quality factor Q.
  • the curve shown in Figure 10 is a slowness curve intercepted near 0° in the range of 0° to 360° in the X-Y plane.
  • the slowness curve S3 is the slowness curve when the piezoelectric layer material and the electrode material are combined into another material
  • the slowness curve S2 is the slowness curve of the base material itself
  • the slowness curve S2 is the slowness curve of the base material itself.
  • the slowness curve S4 is the slowness curve when the piezoelectric layer, electrode and substrate are combined into another material. That is, after the piezoelectric layer, electrode and substrate provided in the embodiment of the present application are combined into one material, the slowness curve S4 will be obtained.
  • the relatively flat slowness curve S4 in Figure 10 enables the transverse mode of the surface acoustic wave resonator to be effectively suppressed.
  • the tetragonal crystal system material of the substrate 301 includes at least one of lithium borate (for example, lithium tetraborate Li 2 B 4 O 7 ), quartz, and tellurium oxide (TeO 2 ).
  • lithium borate for example, lithium tetraborate Li 2 B 4 O 7
  • quartz for example, quartz
  • the material of the piezoelectric layer 302 includes at least one of lithium tantalate (LiTaO 3 ), lithium niobate (LiNbO 3 ), aluminum nitride (AlN), and zinc oxide (ZnO).
  • LiTaO 3 lithium tantalate
  • LiNbO 3 lithium niobate
  • AlN aluminum nitride
  • ZnO zinc oxide
  • the electromechanical coupling coefficient K 2 of the resonator needs to be determined, because the greater the electromechanical coupling coefficient K 2 , the greater the resonance The higher the conversion efficiency of the resonator, the better the performance of the surface acoustic wave resonator SAW.
  • the electromechanical coupling coefficient K 2 When characterizing the electromechanical coupling coefficient K 2 , it can be measured by the size of the Euler angle of the piezoelectric material of the piezoelectric layer 302 . For example, see Figure 11. The abscissa in Figure 11 shows the Euler angle when lithium tantalate is selected as the piezoelectric material, and the ordinate shows the electromechanical coupling coefficient K 2 corresponding to different Euler angles.
  • the piezoelectric material with a large electromechanical coupling coefficient K2 shown in Figure 11 can be used.
  • the surface acoustic wave resonator 300A provided by the embodiment of the present application not only has a relatively flat slowness curve, but also has a large electromechanical coupling coefficient K 2 to further improve the working performance of the surface acoustic wave resonator 300A.
  • the performance of the surface acoustic wave resonator can be evaluated.
  • the surface acoustic wave resonator can also be judged by frequency temperature stability. working performance.
  • the temperature characteristics of the tetragonal crystal system material of the substrate 301 are opposite to the temperature characteristics of the material of the piezoelectric layer 302 .
  • the tetragonal crystal system material has a positive temperature coefficient
  • the material of the piezoelectric layer 302 has a negative temperature coefficient.
  • the tetragonal crystal system material with a positive temperature coefficient as the temperature increases, the frequency increases, and the piezoelectric material with a negative temperature coefficient increases.
  • layer material as the temperature increases, the frequency decreases.
  • the sensitivity of the surface acoustic wave resonator 300A to temperature can be reduced by combining the positive and negative temperature characteristics of the base 301 material and the piezoelectric layer 302 material, so as to improve the frequency and temperature stability.
  • the temperature compensation coefficient of the resonator can be used
  • TCF temperature coefficient of frequency
  • TCF temperature coefficient of velocity
  • TCV TCF+ ⁇ ( ⁇ is the thermal expansion coefficient of the substrate in the propagation direction of the surface acoustic wave resonator SAW, which generally needs to be obtained through experimental testing), as follows:
  • 20-LT represents the values of TCVr and TCVa when the piezoelectric layer material is lithium tantalate (LiTaO 3 ) with an Euler angle of 20° and the substrate is a silicon substrate;
  • 20-LT/ LBO represents the TCVr when the piezoelectric layer 302 material selected in the embodiment of the present application is lithium tantalate (LiTaO 3 ) with an Euler angle of 20°, and the substrate 301 material is selected lithium tetraborate (Li 2 B 4 O 7 ).
  • TCVr is the TCV coefficient of the resonance point in the surface acoustic wave resonator
  • TCVa is the TCV coefficient of the anti-resonance point in the surface acoustic wave resonator.
  • Table 1-2 shows the corresponding TCV coefficient and electromechanical coupling coefficient K 2 when the piezoelectric layer 302 uses materials with different Euler angles.
  • the surface acoustic wave resonator 300A not only has better frequency and temperature stability, but also has an ideal electromechanical coupling coefficient K 2 , and the surface acoustic wave resonator 300A also has better working performance.
  • Curve 1 in Figure 12 is the admittance curve when lithium tetraborate (Li 2 B 4 O 7 ) is selected as the substrate 301 in the embodiment of the present application.
  • Curve 2 is when the substrate 301 is selected not to include lithium tetraborate (Li 2 B 4 Admittance curve of O 7 ) silicon substrate.
  • the abscissa represents frequency, and the ordinate represents admittance.
  • curve 2 From the comparison of curve 1 and curve 2 in Figure 12, it can be seen that when the substrate 301 is a silicon substrate, the admittance curve has many peaks. For example, in Figure 12, the peak T1, the peak T2, and the peak T2 are exemplarily shown. T3 and peak T4, however, curve 2 is relatively smooth. In other words, compared with curve 1, curve 2 can effectively suppress the transverse mode or other stray modes to improve the working performance of the surface acoustic wave resonator 300A.
  • the sound wave propagation speed of the tetragonal crystal material of the substrate 301 provided in the embodiment of the present application is greater than the sound wave propagation speed of the material of the piezoelectric layer. That is, the substrate 301 has high sound velocity characteristics. In this case, the substrate 301 can reflect the energy leaked from the upper piezoelectric layer 302, thereby improving the quality factor Q value.
  • the substrate 301 containing tetragonal crystal material provided in this application can not only interact with the piezoelectric layer 302 and the electrode 303 to make the slowness curve of the formed resonator flatter, but also suppress the piezoelectricity.
  • the leakage of energy from layer 302 further improves the working performance of the resonator.
  • FIG. 13 is a structural diagram of another surface acoustic wave resonator 300A according to an embodiment of the present application.
  • an electrode is formed on the piezoelectric layer 302 and used to apply voltage to the piezoelectric layer 302. It includes a first electrode 3031 and a second electrode 3032.
  • electrical signals can be applied to the first electrode 3031 and the second electrode 3032 respectively, and a potential difference is formed between the two electrodes, further generating a piezoelectric effect.
  • Figure 14 is the M-direction view of Figure 13.
  • either of the first electrode 3031 and the second electrode 3032 can extend in a direction parallel to the substrate 301.
  • the piezoelectric layer 302 and electrodes are stacked on the substrate 301 along the Z direction, and both the first electrode 3031 and the second electrode 3032 extend along the Y direction perpendicular to the Z direction.
  • the first electrode 3031 and the second electrode 3032 are arranged along the X direction perpendicular to the Z direction.
  • the electrodes include a plurality of first electrodes 3031 arranged in parallel, and a plurality of second electrodes 3032 arranged in parallel, and, the plurality of first electrodes 3031 and a plurality of The second electrodes 3032 are alternately arranged along the arrangement direction (which may also be referred to as the first direction perpendicular to the extending direction).
  • first electrodes 3031 may be connected through a first electrode bus
  • second electrodes 3032 may be connected through a second electrode bus.
  • the extending direction of the first electrode bus line may be perpendicular to the first electrode 3031
  • the extending direction of the second electrode bus line may be perpendicular to the second electrode 3032 .
  • Figure 15 only shows one arrangement method of multiple electrodes. Of course, other arrangement structures can also be used.
  • the surface acoustic wave resonator 300A is opposite to the characteristics of the second slowness curve of the tetragonal crystal material. , when the suppression of transverse modes is enhanced, weaker transverse modes may still remain.
  • This application also provides some embodiments that can further enhance lateral mode suppression, as described below.
  • FIG. 16 is a structural diagram cut along line A-A in FIG. 14 .
  • the thickness of the end portion of the first electrode 3031 is greater than the thickness of the middle portion of the first electrode 3031 between the two ends. That is, as shown in Figure 16, the thickness of the first end Q1 of the first electrode 3031 is greater than the thickness of the middle portion Q3 of the first electrode 3031, or the thickness of the second end Q2 of the first electrode 3031 is greater than The thickness of the middle portion Q3 of the first electrode 3031, or the thickness of the first end portion Q1 and the second end portion Q2 of the first electrode 3031, are both greater than the thickness of the middle portion Q3 of the first electrode 3031.
  • the “thickness” mentioned in this application refers to the size of the structure along the stacking direction of the substrate 301 and the piezoelectric layer 302.
  • the thickness of the first end Q1 refers to the size of the first end Q1 along the stacking direction. Z-direction size.
  • the sound wave propagation at the end portion of the first electrode 3031 can be reduced.
  • the speed is such that the wave vector of the transverse mode at the end of the first electrode 3031 is substantially 0, so as to achieve substantially complete suppression of the transverse mode.
  • the thickness of the first end Q1 and the second end Q2 of the first electrode 3031 are both greater than the thickness of the middle part Q3
  • the thickness of the first end Q1 and the thickness of the second end Q2 may be as shown in FIG. 16 They may be equal, or they may be unequal as shown in Figure 17.
  • the thickness of the first end Q1 is greater than the thickness of the second end Q2.
  • the thickness of at least one of the two ends of the second electrode 3032 can also be made larger than the thickness of the middle portion between the two ends. Thickness size.
  • the thickness of the end of the first electrode 3031 when at least one end thickness dimension of the first electrode 3031 is greater than the thickness dimension of the middle portion of the first electrode 3031, and at least one end thickness dimension of the second electrode 3032 is greater than the second As for the thickness of the middle part of the electrode 3032, the thickness of the end of the first electrode 3031 may be equal to the thickness of the end of the second electrode 3032, or may not be equal.
  • the suppression of transverse modes is also enhanced by changing the thickness dimensions of the electrode ends. Compared with simply changing the end thickness of the electrode to enhance the suppression of the transverse mode, the electromechanical coupling coefficient K 2 can be improved.
  • FIG. 18 is a structural diagram of another surface acoustic wave resonator 300A that can further enhance transverse mode suppression provided by the embodiment of the present application. Specifically, along the direction perpendicular to the extending direction of the first electrode 3031, the width dimension of at least one end of the first electrode 3031 is greater than the width dimension of the middle portion Q3 of the first electrode 3031 located between the two ends. For example, in FIG. 18 , the width dimension d1 of the first end Q1 of the first electrode 3031 is larger than the width dimension d2 of the middle part Q3.
  • the width dimension of the second end Q2 of the first electrode 3031 may also be larger than the width dimension of the middle part Q3.
  • the width dimension of the first end Q1 and the second end Q2 of the first electrode 3031 are both larger than the width dimension of the middle part Q3.
  • the width of the end of the first electrode 3031 is changed, which is similar to increasing the thickness of the end of the first electrode 3031.
  • the sound wave propagation speed at the end of the first electrode 3031 can be reduced so that the wave vector of the transverse mode at the end of the first electrode 3031 is substantially 0, so that the transverse mode is substantially completely suppressed.
  • the width of at least one of the two ends of the second electrode 3032 can also be made larger than that of the two ends.
  • the thickness dimension of the end portion of the first electrode 3031 may be greater than the thickness dimension of the middle portion.
  • the width dimension of the end portion of the first electrode 3031 may also be greater than the width dimension of the middle portion.
  • the thickness dimension of the end portion of the second electrode 3032 can be greater than the thickness dimension of the middle portion.
  • the width dimension of the end portion of the second electrode 3032 can also be greater than the width dimension of the middle portion. size.
  • the above-mentioned method of further suppressing the transverse mode by changing the thickness dimension of the end of the electrode, or by changing the width dimension of the end of the electrode, can be called suppressing the transverse mode by changing the piston mode structure.
  • FIG. 19 and FIG. 20 are structural diagrams of other surface acoustic wave resonators 300A according to embodiments of the present application, and FIG. 20 is a three-dimensional view of FIG. 19 . 19 and 20 together, in this surface acoustic wave resonator 300A, not only the substrate 301, the piezoelectric layer 302 and the electrode 303 mentioned above are included, but also the substrate 301 and the piezoelectric layer 302 are formed between the substrate 301 and the piezoelectric layer 302. dielectric layer 304.
  • the material of the substrate 301 includes a tetragonal crystal system material, the characteristics of the first slowness curve synthesized by the material of the piezoelectric layer and the material of the electrode, and the second slowness curve of the tetragonal crystal system material.
  • the characteristics of the slowness curve are opposite.
  • the dielectric layer 304 may be selected from at least one of SiO 2 , SiOF, SiOC, and Ta 2 O 5 , or other dielectric materials may be selected.
  • the surface acoustic wave resonator 300A shown in FIGS. 19 and 20 due to the addition of the dielectric layer 304 , the surface acoustic wave resonator 300A can be reduced in thickness direction (that is, along the Z shown in FIGS. 19 and 20 ). direction), the quality factor Q value is further improved, thereby further improving the working performance of the resonator.
  • the surface acoustic wave resonator 300A includes a plurality of first electrodes 3031 and a plurality of second electrodes 3032, and the plurality of first electrodes 3031 and the plurality of second electrodes 3032 alternate. , equally spaced, and arranged in period P1.
  • a plurality of first electrodes 3031 and a plurality of second electrodes 3032 can be arranged alternately and equally spaced along the X direction parallel to the substrate, and these arrangement periods are P1 , the X direction here can be understood as a direction perpendicular to the extension direction of the first electrode or the second electrode.
  • the arrangement period P1 of the electrodes can be understood in this way, see Figure 21.
  • the electrodes include the adjacent first group of electrodes and the second group of electrodes.
  • the first group of electrodes includes the adjacent first electrodes and the second electrodes.
  • the second group of electrodes includes Adjacent first electrode and second electrode, in the first group of electrodes, there is a center line T1 between the first electrode and the second electrode, in the second group of electrodes, there is a center line T1 between the first electrode and the second electrode.
  • the distance between line T2, center line T1 and center line T2 is period P1.
  • the spacing between two adjacent first electrodes is P1
  • the second electrode located between the two adjacent first electrodes is located within this spacing area.
  • P1 is explained above.
  • the quality factor Q of the resonator can be improved.
  • the abscissa in Figure 22 represents the frequency, and the ordinate represents the quality factor Q
  • curve 1 is the quality factor Q curve when the surface acoustic wave resonator 300A is not provided with a dielectric layer.
  • the electromechanical coupling coefficient K 2 is also improved compared to the resonator without the dielectric layer.
  • the value range of the Euler angle ⁇ of the piezoelectric layer 302 in this embodiment is: 10° ⁇ 50°.
  • ⁇ 10°, 15°, 20°, 25°, 30°, 35°, 40°, 50°, etc.
  • Figure 23 is the slowness curve of several surface acoustic wave resonators with different structures given in the embodiment of the present application.
  • t AL in FIG. 22 is the thickness dimension of the electrode when the electrode is made of aluminum material.
  • the value range of the Euler angle ⁇ of the piezoelectric layer 302 can be: 10° ⁇ 30°.
  • ⁇ 10°, 15°, 20°, 25°, 30°, etc.
  • LiTaO 3 lithium tantalate
  • Table 1-4 shows the electromechanical coupling coefficient K 2 of the above three surface acoustic wave resonators with different structures. See the following table for details.
  • the dielectric layer uses SiO 2 , and the base is lithium tetraborate (Li 2 B 4 O 7 ), compared with the surface acoustic wave resonance
  • the dielectric layer uses SiO 2
  • the substrate is a silicon substrate
  • the electromechanical coupling coefficient K 2 is also improved.
  • tele in the above Table 1-4 is the thickness dimension of the electrode.
  • the frequency band width is larger than that of the existing surface acoustic wave resonator. In this way, the resonator will also be significantly optimized. work performance.
  • the surface acoustic wave resonators provided by the present application can improve the slowness curve and flatten the slowness curve to suppress the lateral direction.
  • the generation of modal and other spurious modes can also improve the frequency and temperature stability of the device, and also increase the electromechanical coupling coefficient.
  • the working performance of the resonator is greatly improved.

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Abstract

本申请实施例提供一种声表面波谐振器、滤波器和通讯设备，涉及谐振器技术领域，可以使得声表面波谐振器实现平坦的慢度曲线。该声表面波谐振器可以包括：基底、压电层和电极，压电层设置在基底上，电极设置在压电层的远离基底的一侧；其中，基底的材料为四方晶系材料；由压电层的材料和电极的材料合成的第一慢度曲线，与四方晶系材料的第二慢度曲线，在该声表面波谐振器的波传播方向上的凹凸特性相反。这样的话，通过特性相反的慢度曲线的相互抵消，可以使得最终的谐振器在波传播方向上的慢度曲线平坦，以抑制横向模态。

Description

声表面波谐振器、滤波器、通讯设备
本申请要求于2022年06月30日提交国家知识产权局、申请号为202210763494.3、发明名称为“声表面波谐振器、滤波器、通讯设备”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
本申请涉及谐振器技术领域，尤其涉及一种声表面波谐振器、具有声表面波谐振器的滤波器，以及包含声表面波滤波器的通讯设备。
背景技术
随着通讯技术的发展，智能手机等通讯设备所需要的谐振器的用量将显著上升。其中，广泛被应用的是声表面波谐振器(surface acoustic wave，SAW)。声表面波谐振器SAW是利用压电效应实现电-声-电换能，具有结构尺寸小等优点，另外，通过声表面波谐振器SAW的串并联可以实现具有低插损、高矩形系数的射频滤波器。
在声表面波谐振器SAW中，横向模态或其它杂散模态的存在，会降低品质因数(也可以叫Q因数)，并且可能会影响滤波器带内平坦度，即降低滤波器的工作性能。
所以，设计一种可以抑制横向模态，提升品质因数的声表面波谐振器，是本领域技术人员目前需要攻克的难题。
发明内容
本申请的实施例提供一种声表面波谐振器、滤波器和通讯设备。提供可以实现平坦的慢度曲线的声表面波谐振器，从而抑制该声表面波谐振器产生横向模态，以提升该谐振器的品质因数。
为达到上述目的，本申请的实施例采用如下技术方案：
一方面，本申请提供了一种声表面波谐振器，该声表面波谐振器可以被应用在滤波器中。
该声表面波谐振器可以包括：基底、压电层和电极，压电层设置在基底上，电极设置在压电层的远离基底的一侧，比如，该电极可以包括给压电层施加电压的第一电极和第二电极；其中，基底的材料为四方晶系材料；由压电层的材料和电极的材料合成的第一慢度曲线，与四方晶系材料的第二慢度曲线，在该声表面波谐振器的波传播方向上的凹凸特性相反。
本申请给出的声表面波谐振器中，采用的是四方晶系的基底材料，并且，由压电层的材料和电极的材料合成的第一慢度曲线的特性，与四方晶系材料的第二慢度曲线的特性相反。这样的话，利用压电层材料和电极材料合成的第一慢度曲线，与四方晶系材料的第二慢度曲线的特性相互抵消，就会使得最终的声表面波谐振器在该声表面波的波传播方向上的慢度曲线呈平坦状态。
在声表面波谐振器中，慢度曲线越平坦，横向模态或者其他杂散模态被抑制的效果越好，从而，在本申请中，通过实现的平坦的慢速曲线，即就是，可以增强横向模态的抑制，进而可以提升该声表面波谐振器的品质因数。
另外，本申请给出的声表面波谐振器不仅可以实现上述平坦的慢度曲线，还可以改善温度补偿系数(temperature coefficient of frequency，TCV)，提升该声表面波谐振器的频率温度稳定性，以进一步的优化该谐振器的工作性能。
在一种可以实现的方式中，压电层的材料的欧拉角φ取值范围为：0°≤φ≤40°。比如，可以选择φ＝20°，或者φ＝10°，又或者φ＝15°，再或者φ＝30°。
当压电材料的欧拉角φ取值范围为：0°≤φ≤40°时，相比相关技术的φ＝42°，甚至更大的欧拉角，本申请的压电材料的欧拉角φ明显的减小。其中，欧拉角φ与机电耦合系数的基本关系为：欧拉角φ越小，机电耦合系数越大，进而，谐振器的性能越优。所以，本申请的压电材料的欧拉角φ选择：0°≤φ≤40°时，会提升该谐振器的机电耦合系数。这样的话，本申请给出的声表面波谐振器不仅具有平坦的慢速曲线，抑制横向模态的产生，还可以提高机电耦合系数和频率温度稳定性，以使得该声表面波谐振器的工作性能更优。
在一种可以实现的方式中，压电层的材料的欧拉角φ取值范围为：0°≤φ≤20°。
在一种可以实现的方式中，四方晶系材料的温度特性与压电层的材料的温度特性相反。
比如，四方晶系材料具有正温度系数，压电层的材料具有负温度系数，那么，四方晶系材料和压电层材料的相互作用，可以降低该谐振器性能对温度的敏感度，以提升谐振器的频率温度稳定性。
在一种可以实现的方式中，四方晶系材料的声波传播速度大于压电层的材料的声波传播速度。
由于四方晶系材料的声波传播速度大于压电层的材料的声波传播速度，进而，该基底能够反射上方压电层泄漏的能量，从而提高该谐振器的品质因数Q值。
在一种可以实现的方式中，基底的四方晶系材料包含四硼酸锂、石英、氧化碲中的至少一种。
在一种可以实现的方式中，压电层包括钽酸锂、铌酸锂、氮化铝、氧化锌中的至少一种。当然，也可以选择其他的压电材料。
比如，在一些实现结构中，基底为四硼酸锂，压电层采用欧拉角φ＝20°的钽酸锂。
在一种可以实现的方式中，声表面波谐振器还包括介质层，介质层设置在基底和压电层之间。
也可以这样理解，在该实现结构中，可以在基底和压电层之间堆叠介质层，通过增加介质层，可以进一步降低该声表面波谐振器沿厚度方向的能量泄露，进一步提升品质因数。
在一种可以实现的方式中，当声表面波谐振器不仅包括基底和压电层，还包括形成在基底和压电层之间的介质层时，压电层的欧拉角φ取值范围可以为10°≤φ≤50°。
比如，压电层的材料的欧拉角选择φ＝10°，或者φ＝20°，又或者φ＝30°，再或者φ＝40°或者φ＝50°。
在一种可以实现的方式中，当声表面波谐振器不仅包括基底和压电层，还包括形成在基底和压电层之间的介质层时，压电层的欧拉角φ取值范围可以为：10°≤φ≤30°。
在一种可以实现的方式中，电极包括多个第一电极和多个第二电极，多个第一电极和多个第二电极以周期P1呈交替排布；介质层的厚度t小于或者等于P1。
针对介质层的厚度，是有设计要求的，比如，介质层的厚度t小于或者等于P1，这样，通过引入合适厚度的介质层，还可以进一步提升该谐振器器件的频率温度稳定性和机电耦合系数。
在一种可以实现的方式中，t＝kP1，k的取值范围为：0.1≤k≤0.5。或者，k的取值范围为：0.1≤k≤0.3。
在一种可以实现的方式中，多个第一电极和多个第二电极沿第一方向等间距交替排列，第一方向是与第一电极和第二电极的延伸方向相垂直的方向。
在一种可以实现的方式中，介质层包括SiO2、SiOF，SiOC，Ta2O5中的至少一种。
诸如上述示例给出的介质材料，均属于正温度系数介质材料，当然，也可以选择其他正温度系数介质材料。
在一种可以实现的方式中，沿基底、压电层和电极的堆叠方向，电极的至少一个端部的厚度，大于电极的位于两个端部之间的中间部分的厚度。
即就是，在本申请中，可以将电极端部的厚度设计的大于电极的中间部分的厚度，如此的话，通过进一步改变电极的端部的厚度尺寸，可以完全抑制横向模态，或者完全抑制其他杂散模态，使得该声表面波谐振器的品质因数更优。
在一种可以实现的方式中，电极的至少一个端部沿第一方向的宽度，大于电极的中间部分沿第二方向的宽度，第一方向是与第一电极和第二电极的延伸方向相垂直的方向。
和上述改变电极端部厚度尺寸一样，通过改变电极端部的宽度尺寸，可以进一步的抑制横向模态，或者其他杂散模态，进一步的优化该谐振器的使用性能。
另一方面，本申请还提供一种滤波器，滤波器包括多个电连接的声表面波谐振器，多个声表面波谐振器中的至少一个声表面波谐振器为上述任一项实现方式中的声表面波谐振器。
本申请给出的滤波器中，由于可以采用上述任一实现方式中的声表面波谐振器，所以，通过声表面波谐振器增强了对横向模态的抑制，从而，可以实现具有低插损、高矩形系数的射频滤波器。
本申请给出滤波器可以是SAW梯形滤波器，SAW网格型滤波器，SAW DMS滤波器，以及它们的混合结构；
又一方面，本申请还提供一种通讯设备，该通讯设备包括放大器和该上述任一实现方式中的滤波器，并且，滤波器与放大器电连接。
本申请实施例提供的通讯设备包括上述任一实现方式中的滤波器，因此本申请实施例提供的通讯设备与上述技术方案的声表面波谐振器能够解决相同的技术问题，并达到相同的预期效果。
附图说明
图1为通讯设备中的部分结构示意图；
图2为通讯设备中的部分结构示意图；
图3为通讯设备中的滤波器的部分结构示意图；
图4为本申请实施例给出的声表面波谐振器的结构示意图；
图5为本申请实施例给出的多种具有不同欧拉角的压电材料的慢度曲线；
图6为本申请实施例给出的声表面波谐振器的结构示意图；
图7为本申请实施例给出的一种在X-Y平面内布设的晶片示意图；
图8为本申请实施例给出的一种压电层材料的慢度曲线；
图9为本申请实施例给出的一种基底材料的慢度曲线；
图10为本申请实施例给出的一种压电层材料、基底材料和声表面波谐振器的慢度曲线；
图11为本申请实施例给出的多种具有不同欧拉角的压电材料的机电耦合系数；
图12为本申请实施例给出的声表面波谐振器和相关技术中的声表面波谐振器的导纳曲线；
图13为本申请实施例给出的声表面波谐振器的结构示意图；
图14为图13的M向视图；
图15为本申请实施例给出的声表面波谐振器的结构示意图；
图16为图14的A-A剖切图；
图17为本申请实施例给出的声表面波谐振器的结构示意图；
图18为本申请实施例给出的声表面波谐振器的结构示意图；
图19为本申请实施例给出的声表面波谐振器的结构示意图；
图20为本申请实施例给出的声表面波谐振器的结构示意图；
图21为本申请实施例给出的声表面波谐振器的结构示意图；
图22为本申请实施例给出的多种声表面波谐振器的品质因数曲线；
图23为本申请实施例给出的多种声表面波谐振器的慢度曲线；
图24为本申请实施例给出的多种声表面波谐振器的导纳曲线。
附图标记：
100-通讯设备；
200-滤波器；
300-声表面波谐振器；
400-放大器；
500-天线；
600-接收机；
700-发射机；
800-基带芯片；
900-开关；
601、603、701-滤波器；602-低噪声放大器；604-混频器；605-缓冲器；606、704-压控振荡
器；702-放大器；703-驱动器；
300A-声表面波谐振器；
301-基底；
302-压电层；
303-电极；3031-第一电极；3032-第二电极；
304-介质层。
具体实施方式
在介绍本申请实施例可以实现的结构之前，先介绍本申请实施例涉及的技术术语。
机电耦合系数K2：是谐振器的一个关键参数，机电耦合系数K2可以反映机械能与电能间的转换效率，谐振器的机电耦合系数K2决定了谐振器串、并联谐振频率的差值，当谐振器运用于滤波器设计中时，这一差值直接决定了滤波器的带宽。可以认为，机电耦合系数K2越大，谐振器的转换效率越高，性能越佳。
品质因数Q：代表了器件的能量利用率，即在一个振动周期内，器件接收到的总能量与耗散掉的能量的比值。在滤波器的设计中，构成滤波器的谐振器的机电耦合系数K2与品质因数Q值均为重要的参数。
压电材料的欧拉角(euler angle)：在声表面波谐振器SAW中，欧拉角(euler angle)表示法是一种表示晶片表面法线的结晶方向，和与声表面波谐振器SAW传播方向重合的基准面方向的方法。该欧拉角也可以被称为切角。
慢度特性、慢度曲线：慢度特性通常采用慢度曲线表征，慢度特性是衡量波在一种介质中传播的物理参数，慢度是速度的倒数，因此，波的传播时间是波传播的距离乘以介质的慢度。
四方晶系：布拉维晶格在三维平面上有七大晶系，分别为三斜晶系、单斜晶系、正交晶系、四方晶系、立方晶系、三方晶系、六方晶系。
导纳(admittance)：是电导和电纳的统称，在电力电子学中导纳定义为阻抗(impedance)的倒数，符号Y，单位是西门子，简称西(S)。和阻抗一样，导纳也是一个复数，由实数部分(电导G)和虚数部分(电纳B)组成:Y＝G+jB。
本申请实施例提供一种通讯设备，该通讯设备包括但不限于射频前端、滤波放大模块等产品，还可以包括手机(mobile phone)、平板电脑(pad)、智能穿戴产品(例如，智能手表、智能手环)、虚拟现实(virtual reality，VR)设备、增强现实(augmented reality，AR)、无人机等终端设备。本申请实施例对上述通讯设备的具体形式不做特殊限制。
在诸如上述的通讯设备中，如图1所示，通讯设备100可以包括滤波器200，滤波器200可以对信号中特定频率的频点或该频点以外的频率进行有效滤除，得到一个特定频率的信号，或消除一个特定频率后的信号，以提升该通讯设备100的工作性能。
图2给出在一些通讯设备100中的部分电路图。其中，见图2，该通讯设备100包括接收机(Receiver)600、发射机(Transmitter)700、天线(Antenna)500和基带芯片800。天线500通过开关900与接收机600和发射机700分别电连接，以及，接收机600和发射机700分别与基带芯片800电连接。
在图2所示的接收机(Receiver)600中，包括滤波器(Filter)601和滤波器(Filter)603，滤波器601和滤波器603之间电连接有低噪声放大器602，滤波器603通过混频器(Mixer)604与缓冲器(Buffer)605电连接，缓冲器605与压控振荡器606电连接。图2仅是一种示例性的接收机，可以在此电路结构基础上增加电子器件或者减少电子器件。
在图2所示的发射机(Transmitter)700中，包括功率放大器(power amplifier，PA)702，功率放大器702与滤波器701和驱动器(Driver)703分别电连接，驱动器(Driver)703与压控振荡器704电连接。类似的，图2仅是一种示例性的发射机，可以在此电路结构基础上增加电子器件或者减少电子器件。
比如，在图2所示的发射机700中，滤波器可以对功率放大器放大后的特定频率的频点或该频点以外的频率进行有效滤除，或者，滤波器可以对低噪声放大器的杂音讯进行滤除。
再如图3所示，滤波器200可以包括多个串联的谐振器300，或者，包括多个并联的谐振器300，又或者，包括串并联相组合的谐振器300。
还有，本申请涉及的滤波器可以是SAW梯形滤波器，SAW网格型滤波器等，或者这些结构的组合。
滤波器200包括的多个谐振器中的至少一个可以为声表面波谐振器(surface acoustic wave，
SAW)。
声表面波谐振器SAW主要作用原理是采用压电的压电特性，利用输入与输出换能器
(Transducer)将电波的输入讯号转换成机械能，经过处理后，再把机械能转换成电的讯号，以达到过滤不必要的讯号及杂讯，提升收讯品质的目标。
如图4所示，图4示出的是一种声表面波谐振器SAW 300A的结构示意图。该声表面波谐振器SAW 300A主要包括基底301、压电层302和电极303。其中，压电层302堆叠在基底301上，电极303堆叠在压电层302的远离基底301的一侧，即就是电极303堆叠在压电层302上。
图4所示的声表面波谐振器SAW 300A在工作时，可以通过电极303给压电层302施加电压，使得压电层302利用压电效应，产生电能和机械能之间的转换。
在其他一些实现结构中，基于图4所示结构，可以在压电层302和基底301之间堆叠其他层结构，比如，介质层，或者其他功能的层结构。
在声表面波谐振器SAW 300A中，影响品质因数Q的主要因素包括声表面波谐振器SAW是否存在通带内的横向模态，或者其他杂散模态。横向模态被抑制的越明显，品质因数Q越优。
其中，表征横向模态时，可以利用材料的慢度特性，即就是慢度曲线的平坦度来衡量。比如，见图5所示，在图5中，给出了多个具有不同欧拉角(也可以叫切角)的压电材料(比如钽酸锂)对应的慢度曲线。分别为：曲线①代表的是欧拉角为20°的压电材料的慢度曲线，曲线②代表的是欧拉角为25°的压电材料的慢度曲线，曲线③代表的是欧拉角为30°的压电材料的慢度曲线，曲线④代表的是欧拉角为35°的压电材料的慢度曲线，曲线⑤代表的是欧拉角为40°的压电材料的慢度曲线，曲线⑥代表的是欧拉角为60°的压电材料的慢度曲线。
基于图5，可以看出：低切角的慢度曲线相对凸出，比如，切角为20°时的曲线①、切角为25°时的曲线②、切角为30°时的曲线③、切角为35°时的曲线④，这些具有凸出的慢度曲线对应的压电材料制作的声表面波谐振器很难抑制横向模态，因此，具有这些切角的材料制得声表面波谐振器SAW 300A的品质因数Q也较差，声表面波谐振器SAW 300A的使用性能也不佳。
所以，为了使得声表面波谐振器SAW 300A的慢度曲线平坦化，以抑制横向模态，提升品质因数Q。本申请实施例给出了一些声表面波谐振器SAW 300A，这些声表面波谐振器SAW 300A慢度曲线比较平坦，品质因数Q较高，具体可以实现的结构见下述。
图6是本申请实施例给出的声表面波谐振器SAW 300A的三维结构图，和上述图4所示的声表面波谐振器SAW 300A相同的是，图6所示的声表面波谐振器SAW 300A也包括基底301、堆叠在基底301上的压电层302，和堆叠在压电层302上的电极303。
在本申请给出的图6所示的实施例中，基底301的材料为四方晶系材料。
另外，压电层302的材料的慢度曲线和电极303的材料的慢度曲线合成的第一慢度曲线，与四方晶系材料的第二慢度曲线，在该声表面波谐振器的波传播方向上的凹凸特性相反。
下面结合图7至图10对上述涉及的“压电层302的材料的慢度曲线和电极303的材料的慢度曲线合成的第一慢度曲线，与四方晶系材料的第二慢度曲线，在该声表面波谐振器的波传播方向上的凹凸特性相反”进行解释，具体如下。
先介绍声表面波谐振器的波传播方向，如图6所示，压电层302和基底301堆叠的方向可以被称为Z方向，压电层302和基底301分别处于与Z方向相垂直的X-Y平面内。进而，可以理解为：波在X-Y平面内的传播方向为该声表面波谐振器的波传播方向。
如图8和图9所示的，图8和图9中，每一个图均示出了三条曲线，并且，是在0°至360°范围内的曲线，也就是在X-Y平面内，0°至360°范围内的慢度曲线。
其中，如图8中的三条曲线为该声表面波谐振器处于不同模态时，压电层302的材料在波传播方向上的慢度曲线。如图9中的三条曲线为该声表面波谐振器处于不同模态时，基底301的材料在波传播方向上的慢度曲线。
在本申请给出的实施例中，如图8和图9，关注于该声表面波谐振器处于其中一种模态时的慢度曲线，例如，压电层302的材料的慢度曲线(如曲线S01)，基底301的材料的慢度曲线(如曲线S02)。
另外，在一些可以实现的方式中，以在X-Y平面内的0°至360°范围内0°左右为例，说明慢度曲线的凹凸特性，比如，在图8中，采用虚线框示出了压电层302的材料在0°附近(这里的0°附近可以理解为0度至30°，以及330°至360°)的慢度曲线S1，在图9中，也采用虚线框示出了基底301的材料在0°附近(该0°附近可以理解为0度至30°，以及330°至360°)的慢度曲线S2。
可以这样理解在X-Y平面内0°至360°范围内的0°，如图7所示的，图7示出了在X-Y平面内布设的晶片示意图，在图7中，基准(orientation flat，OF)通常是与SAW波传播方向相垂直的方向，比如，波传播方向为位置5指向位置4，位置5指向位置2，那么，将OF方向逆时针旋转90°，就为0°至360°范围内的0°。
由图8看出，在0°附近，压电层302的材料的慢度曲线S1呈略微的凹陷。另外，电极303的材料的慢度曲线呈圆形结构，那么，图8所示的压电层302的材料的慢度曲线S1与电极302的材料的慢度曲线相结合后，就会得到图10所示的压电层302的材料的慢度曲线和电极303的材料的慢度曲线合成后的慢度曲线S3(该慢度曲线S3也可以被称为第一慢度曲线，该慢度曲线S3也可以被认为是现有技术中，没有采用四方晶系材料基底时，该声表面波谐振器的慢度曲线)。
由图9看出，在0°附近，基底301的材料的慢度曲线S2(该慢度曲线S2也可以被称为第二慢度曲线)具有较深的凹陷。图10所示的基底301的材料的慢度曲线S2，和图10所示的压电层302的材料的慢度曲线和电极303的材料的慢度曲线合成后的慢度曲线S3相比，具有凹凸特性，那么，该凹凸特性相互抵消后，就会得到图10所示的声表面波谐振器300A的慢度曲线S4，即就是第一慢度曲线和第二慢度曲线的凹凸特性是相反的，可以相互抵消，以实现声表面波谐振器300A的慢度曲线的平坦化。
也可以按照图10，当不采用四方晶系材料基底时，该声表面波谐振器的慢度曲线如图10中的慢度曲线S3所示，而在本申请中，通过将慢度曲线S3与图10中的基底301的材料的慢度曲线S2相互作用，就可以得到图10中的声表面波谐振器300a的慢度曲线S4。也就是说，本申请给出的实施例中，通过改变基底301的材料，可以使得基底301的慢度特性，与压电层和电极的慢度特性相互作用，使得形成的声表面波谐振器SAW 300A的慢度曲线S4趋近平坦，以增强对横向模态的抑制，提升品质因数Q。
其中，图10中所示的曲线是在X-Y平面内0°至360°范围内，截取的0°附近的慢度曲线。
再次对图10所示三条曲线解释如下：慢度曲线S3是将压电层材料和电极材料合为另一种材料时的慢度曲线，慢度曲线S2是基底材料自身的慢度曲线，慢度曲线S4是将压电层、电极和基底合为又一种材料时的慢度曲线，即就是将本申请实施例提供的压电层、电极和基底合为一种材料后，就会得到图10中的比较平坦的慢度曲线S4，以实现该声表面波谐振器的横向模态被有效抑制。
在一些可以选择的实现结构中，基底301的四方晶系材料包括硼酸锂(比如，四硼酸锂Li2B4O7)、石英、氧化碲(TeO2)中的至少一种。
在一些可以选择的实现结构中，压电层302的材料包括钽酸锂(LiTaO3)、铌酸锂(LiNbO3)、氮化铝(AlN)、氧化锌(ZnO)中的至少一种。
在衡量声表面波谐振器SAW 300A的使用性能时，不仅可以通过横向模态被抑制的程度来鉴定，还需要确定该谐振器的机电耦合系数K2，因为机电耦合系数K2越大，谐振器的转换效率越高，声表面波谐振器SAW的性能越佳。
表征机电耦合系数K2时，可以利用压电层302的压电材料的欧拉角(euler angle)大小来衡量。比如，见图11所示的，图11的横坐标示为压电材料选择钽酸锂时的欧拉角，纵坐标示为不同大小欧拉角对应的机电耦合系数K2。
由图11中所示曲线可以得知：当压电材料的欧拉角为接近20°时，机电耦合系数K2最大，欧拉角选择其他数值时，都会相对应的减小机电耦合系数K2，从而也会降低声表面波谐振器300A的性能。
一并结合图5和图11，当压电材料的欧拉角为20°时，机电耦合系数K2较大，但是，欧拉角为20°时，图5所示的慢度曲线凸出，存在横向模态。而当压电材料的欧拉角为40°时，机电耦合系数K2较小，但是，欧拉角为40°时，图5所示的慢度曲线比较平坦，横向模态被有效的抑制。综合所述，在相关技术中，无法通过采用一种压电材料，既可以提升机电耦合系数K2，又可以兼顾使得慢度曲线平坦化。
但是，在本申请实施例中，通过采用四方晶系材料的基底301，就可以采用图11所示的具有较大机电耦合系数K2的压电材料，比如，该压电层的压电材料的欧拉角φ范围可以是0°≤φ≤40°，或者，欧拉角φ范围可以是0°≤φ≤20°，比如，欧拉角φ＝0°、5°、10°、15°、20°、25°、30°、35°、40°等。
这样的话，本申请实施例提供的声表面波谐振器300A不仅具有较平坦的慢度曲线，还具有较大的机电耦合系数K2，以进一步的提升该声表面波谐振器300A的工作性能。
在声表面波谐振器中，除过上述描述的可以通过慢度曲线、机电耦合系数K2评定该声表面波谐振器的性能之外，还可以通过频率温度稳定性，判定声表面波谐振器的工作性能。
在本申请给出的声表面波谐振器300A中，基底301的四方晶系材料的温度特性与压电层302的材料的温度特性相反。
即就是，四方晶系材料具有正温度系数，压电层302的材料具有负温度系数，具有正温度系数的四方晶系材料，随着温度升高，频率升高，具有负温度系数的压电层材料，随着温度升高，频率降低。如此的话，可以通过基底301材料与压电层302材料的正负温度特性组合，降低该声表面波谐振器300A对温度的敏感度，以提升频率温度稳定性。
在表征声表面波谐振器300A的频率温度稳定性时，可以利用谐振器的温度补偿系数
(temperature coefficient of frequency，TCF)的大小来衡量。并且，TCF系数的绝对值越接近零，代表频率温度稳定性越好。
下述给出了评定本申请实施例给出的声表面波谐振器的频率温度稳定性，由于TCF无法直接仿真得到，这里采用速度温度系数(temperature coefficient of velocity，TCV)来表征，其中，TCV＝TCF+α(α为声表面波谐振器SAW的传播方向上基片的热膨胀系数，一般需要通过实验测试得到)，具体如下：
表1-1
上述表1-1中，20-LT代表的是压电层材料选择欧拉角为20°的钽酸锂(LiTaO3)、基底为硅基底时，TCVr和TCVa的取值；20-LT/LBO代表的是本申请实施例给出的压电层302材料选择欧拉角为20°的钽酸锂(LiTaO3)、基底301材料选择四硼酸锂(Li2B4O7)时，TCVr和TCVa的取值。其中，TCVr为声表面波谐振器中谐振点的TCV系数，TCVa为声表面波谐振器中反谐振点的TCV系数。
由上述表1-1可以看出：在相关技术中，当本申请的压电层302材料选择20-LT，基底301材料选择LBO时，和压电层材料选择20-LT、基底选择硅基底时相比，TCVr和TCVa更加明显的接近零。从而，本申请实施例给出的声表面波谐振器的频率温度稳定性更好，明显的得到了改善。
下述表1-2给出了当压电层302采用不同欧拉角材料时，对应的TCV系数和机电耦合系数K2。

表1-2
由上述表1-2可以看出：当压电层材料的欧拉角在40°附近时，TCV系数的绝对值比较接近零，即频率温度稳定性较好。随着欧拉角变小，机电耦合系数K2在不断变大的同时，TCV系数也在恶化。所以，在设计声表面波谐振器300A时，可以根据需求选择不同的切角，比如，在本申请实施例给出的声表面波谐振器300A时，可以选择切角为40°左右的压电层302材料，这样，该声表面波谐振器300A不仅具有较好的频率温度稳定性，同时，机电耦合系数K2也比较理想，该声表面波谐振器300A的工作性能也较优。
图12中的曲线①是本申请实施例给出的基底301选择四硼酸锂(Li2B4O7)时的导纳曲线，曲线②是基底301选择不包含四硼酸锂(Li2B4O7)的硅基底时的导纳曲线。在图12中，横坐标代表的是频率，纵坐标代表的是导纳。
由图12中的曲线①和曲线②对比可以看出：当基底301选择硅基底时，导纳曲线具有很多波峰，比如，在图12中，示例性的示出了波峰T1、波峰T2、波峰T3和波峰T4，但是，曲线②比较光滑。也就是说，曲线②相比曲线①，可以将横向模态或者其他杂散模态被有效的抑制住，以提升该声表面波谐振器300A的工作性能。
在一些实现结构中，本申请实施例给出的基底301的四方晶系材料的声波传播速度大于压电层的材料的声波传播速度。即就是基底301具有高声速特性，这样的话，基底301能够反射上方压电层302泄漏的能量，从而提高品质因数Q值。
可以这样理解，本申请给出的包含四方晶系材料的基底301，不仅可以和压电层302、电极303相互作用，以使得形成的谐振器的慢度曲线更加平坦化，还可以抑制压电层302能量的泄漏，进一步的提升该谐振器的工作性能。
图13是本申请实施例给出的另一种声表面波谐振器300A的结构图，在该实施例中，形成在压电层302上的，且用于给压电层302施加电压的电极包括第一电极3031和第二电极3032。在该声表面波谐振器300A工作时，可以给第一电极3031和第二电极3032分别施加电信号，两个电极之间形成电势差，进一步产生压电效应。
图14是图13的M向视图，在一种可以实现的结构中，第一电极3031和第二电极3032中的任一个电极可以沿着与基底301相平行的方向延伸，例如，在图13和图14中，压电层302和电极沿Z方向堆叠在基底301上，第一电极3031和第二电极3032均沿与Z方向垂直的Y方向延伸。除此之外，第一电极3031和第二电极3032沿与Z方向垂直的X方向排布。
在一些可以实现的结构中，如图15所示，电极包括多个相并列布设的第一电极3031，和多个相并列布设的第二电极3032，并且，多个第一电极3031和多个第二电极3032沿着排布方向(也可以被称为与延伸方向垂直的第一方向)呈交替布设。
另外，多个第一电极3031可以通过第一电极总线相连接，以及，多个第二电极3032可以通过第二电极总线相连接。第一电极总线的延伸方向可以与第一电极3031相垂直布设，第二电极总线的延伸方向可以与第二电极3032相垂直布设。图15仅给出多个电极的其中一种布设方式，当然，也可以采用其他布设结构。
在一些实施例中，当采用上述的压电层的材料和电极的材料合成的第一慢度曲线的特性，与四方晶系材料的第二慢度曲线的特性相反的声表面波谐振器300A，增强对横向模态的抑制时，有可能还会存留较弱的横向模态，
本申请还给出了一些可以进一步增强横向模态抑制的实施例，具体如下所述。
如图16所示，图16是沿着图14的A-A剖切后的结构图。具体的，沿第一电极3031的延伸方向，第一电极3031的端部的厚度，大于第一电极3031的位于两个端部之间的中间部分的厚度。也就是如图16所示的，第一电极3031的第一端部Q1的厚度，大于第一电极3031的中间部分Q3的厚度，或者，第一电极3031的第二端部Q2的厚度，大于第一电极3031的中间部分Q3的厚度，又或者，第一电极3031的第一端部Q1的厚度和第二端部Q2的厚度，均大于第一电极3031的中间部分Q3的厚度。
本申请涉及的“厚度”，指的是结构沿基底301、压电层302堆叠方向的尺寸，比如，在图15中，第一端部Q1的厚度指的是第一端部Q1沿堆叠方向Z方向的尺寸。
在图16所示的结构中，是通过改变第一电极3031的端部的厚度尺寸，当改变第一电极3031的端部的厚度尺寸后，就可以降低该第一电极3031端部的声波传播速度，使得第一电极3031端部的横向模的波矢量基本为0，以实现横向模态的基本完全抑制。
当第一电极3031的第一端部Q1和第二端部Q2的厚度均大于中间部分Q3的厚度时，第一端部Q1的厚度和第二端部Q2的厚度可以是图16所示的相等，也可以是图17所示的不相等，比如，在图17中，第一端部Q1的厚度大于第二端部Q2的厚度。
和第一电极3031类似的，为了进一步的抑制横向模态，也可以使得第二电极3032的两个端部中的至少一个端部的厚度尺寸，大于位于两个端部之间的中间部分的厚度尺寸。
在一些可以实现的结构中，当第一电极3031的至少一个端部厚度尺寸，大于第一电极3031的中间部分的厚度尺寸，以及，第二电极3032的至少一个端部厚度尺寸，大于第二电极3032的中间部分的厚度尺寸时，第一电极3031的端部厚度尺寸，可以和第二电极3032的端部厚度尺寸相等，也可以不相等。
在图16和图17所示的实施例中，不仅压电层的材料和电极的材料合成的第一慢度曲线的特性，与四方晶系材料的第二慢度曲线的特性相反，除外，还通过改变电极的端部厚度尺寸的方式，来增强对横向模态的抑制。相比仅通过改变电极的端部厚度尺寸，来增强对横向模态的抑制，可以提升机电耦合系数K2。
例如，采用上述图16和图17所示方式，和相关技术中的仅改变电极的端部厚度，使得对横向模态抑制强度相当时，明显的电极的厚度会减小，从而，就会降低该谐振器的机电耦合系数K2。
图18是本申请实施例提供的另一种可以进一步增强横向模态抑制的声表面波谐振器300A的结构图。具体的，沿与第一电极3031延伸方向相垂直的方向，第一电极3031的至少一个端部的宽度尺寸，大于第一电极3031位于两个端部之间的中间部分Q3的宽度尺寸。比如，在图18中，第一电极3031的第一端部Q1的宽度尺寸d1，大于中间部分Q3的宽度尺寸d2。
另外，在一些可以选择的实施例中，第一电极3031的第二端部Q2的宽度尺寸，也可以大于中间部分Q3的宽度尺寸。或者，在另外一些可以选择的实施例中，第一电极3031的第一端部Q1和第二端部Q2的宽度尺寸，均大于中间部分Q3的宽度尺寸。
在该实施例中，是通过改变第一电极3031的端部的宽度尺寸，和上述增加第一电极3031的端部的厚度尺寸类似，当改变第一电极3031的端部的宽度尺寸后，就可以降低该第一电极3031端部的声波传播速度，使得第一电极3031端部的横向模的波矢量基本为0，以使得横向模态的基本被完全抑制。
继续见图18所示，和第一电极3031类似的，为了进一步的抑制横向模态，也可以使得第二电极3032的两个端部中的至少一个端部的宽度尺寸，大于位于两个端部之间的中间部分的厚度尺寸。
还有，在一些实现结构中，第一电极3031的端部厚度尺寸，可以大于中间部分的厚度尺寸，同时，第一电极3031的端部的宽度尺寸，也可以大于中间部分的宽度尺寸。
同理的，在一些可以实现的结构中，第二电极3032的端部厚度尺寸，可以大于中间部分的厚度尺寸，同时，第二电极3032的端部的宽度尺寸，也可以大于中间部分的宽度尺寸。
上述的通过改变电极的端部的厚度尺寸，或者，通过改变电极的端部的宽度尺寸，来进一步抑制横向模态的方式，可以被称为通过改变piston mode结构，以抑制横向模态。
为了进一步提升该声表面波谐振器300A的工作性能，本申请实施例还提供了一些声表面波谐振器300A可以实现的结构。比如，图19和图20是本申请实施例给出的另外一些声表面波谐振器300A的结构图，且图20是图19的三维视图。一并结合图19和图20，在此种声表面波谐振器300A中，不仅包括了上述涉及的基底301、压电层302和电极303，还包括形成在基底301和压电层302之间的介质层304。和上述实施例一样，在此种实施例中，基底301的材料包括四方晶系材料，压电层的材料和电极的材料合成的第一慢度曲线的特性，与四方晶系材料的第二慢度曲线的特性相反。
介质层304可以选择SiO2、SiOF，SiOC，Ta2O5中的至少一种，也可以选择其他介电材料。
在图19和图20所示的声表面波谐振器300A中，由于增加了介质层304，可以减小该声表面波谐振器300A沿厚度方向(即就是沿图19、图20所示的Z方向)的能量泄露，进一步提升品质因数Q值，从而，进一步提升该谐振器的工作性能。
在一些可以选择的实现结构中，如图21所示，声表面波谐振器300A包括多个第一电极3031和多个第二电极3032，多个第一电极3031和多个第二电极3032交替的、等间距的排布，且以周期P1排布。
比如，在一些结构中，如图21，多个第一电极3031和多个第二电极3032可以沿着与基底相平行的X方向交替的、等间距的排布，且这些排布周期为P1，这里的X方向可以理解为与第一电极或者第二电极的延伸方向相垂直的方向。
可以这样理解电极的排布周期P1，见图21，电极包括相邻的第一组电极和第二组电极，第一组电极包括相邻的第一电极和第二电极，第二组电极包括相邻的第一电极和第二电极，在第一组电极中，第一电极和第二电极之间具有中心线T1，在第二组电极中，第一电极和第二电极之间具有中心线T2，中心线T1与中心线T2之间的间距就为周期P1。
或者，可以这样理解，相邻的两个第一电极之间的间距为P1，位于相邻的两个第一电极之间的第二电极位于该间距区域内。
在设置图19和图20所示的介质层304时，介质层304的厚度为t；且t＝kP1，k≤1，即为介质层的厚度小于或者等于周期P1。其中，P1见上述解释。比如，k＝0.05、k＝0.1、k＝0.2、k＝0.3、k＝0.4、k＝0.5、k＝0.6、k＝0.7、k＝0.8、k＝0.9、k＝1。
或者，在一些可以选择的结构中，0.1≤k≤0.5。比如，k＝0.1、k＝0.2、k＝0.3、k＝0.4、k＝0.5。
因为当k≤1时，可以提升该谐振器的品质因数Q，比如，见图22所示，图22的横坐标示意的是频率，纵坐标示意的是品质因数Q，并且，曲线①所示的是声表面波谐振器300A没有设置介质层时的品质因数Q曲线，曲线②所示的是介质层304的厚度t＝0.05P1时的品质因数Q曲线，曲线③所示的是介质层304的厚度t＝0.1P1时的品质因数Q曲线，曲线④所示的是介质层304的厚度t＝0.2P1时的品质因数Q曲线，曲线⑤所示的是介质层304的厚度t＝0.3P1时的品质因数Q曲线。
由图22所示的多条曲线可以看出：当声表面波谐振器300A没有设置介质层时，品质因数Q可以被恶化，但是，当介质层304的厚度t＝kP1，k≤1时，明显的，可以改善该谐振器的品质因数Q，提升该声表面波谐振器300A的工作性能。
另外，当声表面波谐振器300A形成有介质层304时，且介质层304的厚度t＝kP1，k≤1时，还可以影响该谐振器的机电耦合系数K2和频率温度稳定性，具体见下述表1-3。
表1-3
基于上述表1-3，可以得知：当包含介质层304时，相比没有设置介质层的声表面波谐振器，TCV系数的绝对值更加接近零，因此，谐振器的频率温度稳定性更优。
还有，当谐振器包含介质层304时，相比没有设置介质层的谐振器，机电耦合系数K2也得到了提升。
再次参阅图19和图20给出的声表面波谐振器300A，本实施例中的压电层302的欧拉角φ取值范围为：10°≤φ≤50°。比如，φ＝10°、15°、20°、25°、30°、35°、40°、50°等。
图23是本申请实施例给出的几种不同结构的声表面波谐振器的慢度曲线。其中，曲线①示意的是压电层采用欧拉角φ＝20°的钽酸锂(LiTaO3)、介质层采用SiO2，以及基底为硅基底的声表面波谐振器的慢度曲线；曲线②示意的是压电层采用欧拉角φ＝20°的钽酸锂(LiTaO3)、没有介质层，以及基底为四硼酸锂(Li2B4O7)的声表面波谐振器的慢度曲线；曲线③示意的是压电层采用欧拉角φ＝30°的钽酸锂(LiTaO3)、介质层采用SiO2，以及基底为四硼酸锂(Li2B4O7)的声表面波谐振器的慢度曲线。并且，图22中的tAL为电极采用铝材料时的电极的厚度尺寸。
对比曲线①和曲线②，可以看出：当本申请采用四方晶系的四硼酸锂(Li2B4O7)时，慢度曲线明显的被平坦化。
以及，对比曲线②和曲线③，可以看出：当本申请实施例提供的声表面波谐振器包括介质层时，可以进一步的使得慢度曲线平坦化。
在一些可以选择的实现结构中，采用图19和图20所示结构时，压电层302的欧拉角φ取值范围可以为：10°≤φ≤30°。比如，φ＝10°、15°、20°、25°、30°等。
图24是本申请实施例给出的几种不同结构的声表面波谐振器的导纳曲线，其中，横坐标示意的是频率，纵坐标示意的是导纳。和上述图23类似的，曲线①示意的是压电层采用欧拉角φ＝20°的钽酸锂(LiTaO3)、介质层采用SiO2，以及基底为硅基底的声表面波谐振器的导纳曲线；曲线②示意的是压电层采用欧拉角φ＝20°的钽酸锂(LiTaO3)、没有介质层，以及基底为四硼酸锂(Li2B4O7)的声表面波谐振器的导纳曲线；曲线③示意的是压电层采用欧拉角φ＝30°的钽酸锂(LiTaO3)、介质层采用SiO2，以及基底为四硼酸锂(Li2B4O7)的声表面波谐振器的导纳曲线。
对比曲线①和曲线②，可以看出：当本申请采用四方晶系的四硼酸锂(Li2B4O7)时，导纳曲线更加光滑，横向模态被抑制的效果更好。
以及，对比曲线②和曲线③，可以看出：当本申请实施例提供的声表面波谐振器包括介质层，导纳曲线进一步的较光滑，横向模态被抑制的效果也更加明显。
还有，下述表1-4给出了上述三个不同结构的声表面波谐振器的机电耦合系数K2，具体见下表。

表1-4
基于上述表1-4，当声表面波谐振器的结构采用φ＝20°的钽酸锂(LiTaO3)、没有介质层，以及基底为四硼酸锂(Li2B4O7)时，相比声表面波谐振器包括欧拉角φ＝20°的钽酸锂(LiTaO3)、介质层采用SiO2，以及基底为硅基底时，机电耦合系数K2得到了提升。当声表面波谐振器的结构采用φ＝30°的钽酸锂(LiTaO3)、介质层采用SiO2，以及基底为四硼酸锂(Li2B4O7)时，相比声表面波谐振器包括欧拉角φ＝20°的钽酸锂(LiTaO3)、介质层采用SiO2，以及基底为硅基底时，机电耦合系数K2也得到了提升。上述表1-4中的tele为电极的厚度尺寸。
在一些可以实现的结构中，采用本申请实施例给出的声表面波谐振器结构时，相比现有的声表面波谐振器，频段宽度更大，这样，也会明显的优化该谐振器的工作性能。
基于上述对本申请实施例提供的多种声表面波谐振器的结构描述，可以理解为，本申请给出的声表面波谐振器可以使得改善慢度曲线，使得慢度曲线平坦化，以抑制横向模态和其他杂散模态的生成，同时，也可以改善器件的频率温度稳定性，以及，还会提升机电耦合系数。当上述至少三种作用均可以兼顾时，大大的提升了该谐振器的工作性能。
在本说明书的描述中，具体特征、结构、或者特点可以在任何的一个或多个实施例或示例中以合适的方式结合。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可以想到变化或替换，都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (16)

  1. 一种声表面波谐振器，其特征在于，包括：
    基底；
    压电层，设置在所述基底上；
    电极，设置在所述压电层的远离所述基底的一侧；
    其中，所述基底的材料为四方晶系材料；
    由所述压电层的材料和所述电极的材料合成的第一慢度曲线，与所述四方晶系材料的第二慢度曲线，在所述声表面波谐振器的波传播方向上的凹凸特性相反。
  2. 根据权利要求1所述的声表面波谐振器，其特征在于，所述四方晶系材料的温度特性与所述压电层的材料的温度特性相反。
  3. 根据权利要求1或2所述的声表面波谐振器，其特征在于，所述四方晶系材料的声波传播速度大于所述压电层的材料的声波传播速度。
  4. 根据权利要求1-3中任一项所述的声表面波谐振器，其特征在于，所述四方晶系材料包括四硼酸锂、石英、氧化碲中的至少一种。
  5. 根据权利要求1-4中任一项所述的声表面波谐振器，其特征在于，所述声表面波谐振器还包括介质层，所述介质层设置在所述基底和所述压电层之间。
  6. 根据权利要求5所述的声表面波谐振器，其特征在于，所述电极包括多个第一电极和多个第二电极，所述多个第一电极和所述多个第二电极以周期P1呈交替排布；
    所述介质层的厚度t小于或者等于P1。
  7. 根据权利要求6所述的声表面波谐振器，其特征在于，t＝kP1，所述k的取值范围为：0.1≤k≤0.5。
  8. 根据权利要求5-7中任一项所述的声表面波谐振器，其特征在于，所述压电层的材料的欧拉角φ的取值范围为：10°≤φ≤50°。
  9. 根据权利要求8所述的声表面波谐振器，其特征在于，所述欧拉角φ的取值范围为：10°≤φ≤30°。
  10. 根据权利要求5-9中任一项所述的声表面波谐振器，其特征在于，所述介质层包括SiO2、SiOF，SiOC，Ta2O5中的至少一种。
  11. 根据权利要求1-10中任一项所述的声表面波谐振器，其特征在于，
    沿所述基底、所述压电层和所述电极的堆叠方向，所述电极的至少一个端部的厚度，大于所述电极的位于两个端部之间的中间部分的厚度；
    和/或；
    所述电极的至少一个端部沿第一方向的宽度，大于所述电极的所述中间部分沿所述第一方向的宽度，所述第一方向是与所述电极的延伸方向相垂直的方向。
  12. 根据权利要求1-3中任一项所述的声表面波谐振器，其特征在于，所述压电层的材料的欧拉角φ的取值范围为：0°≤φ≤40°。
  13. 根据权利要求12所述的声表面波谐振器，其特征在于，所述欧拉角φ的取值范围为：0°≤φ≤20°。
  14. 根据权利要求1-13中任一项所述的声表面波谐振器，其特征在于，所述压电层包括钽酸锂、铌酸锂、氮化铝、氧化锌中的至少一种。
  15. 一种滤波器，其特征在于，包括：
    多个电连接的谐振器，多个所述谐振器中的至少一个谐振器为权利要求1-14中任一项所述的声表面波谐振器。
  16. 一种通讯设备，其特征在于，包括：
    放大器；
    如权利要求15所述的滤波器，所述放大器与所述滤波器电连接。
PCT/CN2023/103820 2022-06-30 2023-06-29 声表面波谐振器、滤波器、通讯设备 WO2024002237A1 (zh)

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CN114124019A (zh) * 2020-08-28 2022-03-01 株式会社日本制钢所 声表面波谐振器、其制造方法和无线电电路
CN114614790A (zh) * 2022-03-21 2022-06-10 广东广纳芯科技有限公司 声表面波滤波器及其制造方法

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US20200252045A1 (en) * 2019-02-01 2020-08-06 Qorvo Us, Inc. High quality factor transducers for surface acoustic wave devices
CN114124019A (zh) * 2020-08-28 2022-03-01 株式会社日本制钢所 声表面波谐振器、其制造方法和无线电电路
CN112737541A (zh) * 2020-12-24 2021-04-30 北京航天微电科技有限公司 一种tc-saw谐振器、制作方法和滤波器
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