WO2022224470A1 - 共振子 - Google Patents

共振子 Download PDF

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Publication number
WO2022224470A1
WO2022224470A1 PCT/JP2021/039760 JP2021039760W WO2022224470A1 WO 2022224470 A1 WO2022224470 A1 WO 2022224470A1 JP 2021039760 W JP2021039760 W JP 2021039760W WO 2022224470 A1 WO2022224470 A1 WO 2022224470A1
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Prior art keywords
piezoelectric layer
crystal
substrate
acoustic velocity
resonator
Prior art date
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PCT/JP2021/039760
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English (en)
French (fr)
Japanese (ja)
Inventor
俊雄 西村
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Murata Manufacturing Co Ltd
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Murata Manufacturing Co Ltd
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Application filed by Murata Manufacturing Co Ltd filed Critical Murata Manufacturing Co Ltd
Priority to JP2023516025A priority Critical patent/JP7587766B2/ja
Priority to CN202180094132.3A priority patent/CN116888891A/zh
Priority to DE212021000552.7U priority patent/DE212021000552U1/de
Publication of WO2022224470A1 publication Critical patent/WO2022224470A1/ja
Priority to US18/454,954 priority patent/US20230402991A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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 elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H03H9/02574—Characteristics of substrate, e.g. cutting angles of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; 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 elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H03H9/02551—Characteristics of substrate, e.g. cutting angles of quartz substrates
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/02535—Details of surface acoustic wave devices
    • H03H9/02543—Characteristics of substrate, e.g. cutting angles
    • H03H9/02559—Characteristics of substrate, e.g. cutting angles of lithium niobate or lithium-tantalate substrates
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves
    • H03H9/14544—Transducers of particular shape or position
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/25—Constructional features of resonators using surface acoustic waves

Definitions

  • the present invention relates to resonators.
  • SAW surface acoustic wave
  • Patent Document 1 discloses a surface acoustic wave device that includes a piezoelectric substrate and an IDT provided on the piezoelectric substrate and uses an SH wave as an excitation wave, in which a groove is formed in the space between the electrode fingers of the IDT. discloses a surface acoustic wave device with an improved Q value.
  • Patent Document 2 discloses an elastic wave device including a high acoustic velocity support substrate, a piezoelectric film, and an IDT electrode. There is disclosed an elastic wave device in which a low acoustic velocity film having a film thickness in the range of 0.5 ⁇ is provided between a high acoustic velocity support substrate and a piezoelectric film to improve the Q value.
  • Patent Document 3 discloses a surface acoustic wave device in which a crystal layer, an amorphous silicon oxide layer, a piezoelectric layer, and a comb-shaped electrode are laminated in order, and the thickness of the amorphous silicon oxide layer and the thickness of the piezoelectric layer are set to appropriate values.
  • a surface acoustic wave device is disclosed which is intended to improve frequency temperature characteristics and other characteristics.
  • the present invention has been made in view of such circumstances, and an object of the present invention is to provide a resonator that is excellent in frequency-temperature characteristics or resonance characteristics.
  • a resonator includes: a piezoelectric layer having first and second surfaces facing each other; an IDT electrode provided on the side of the first surface of the piezoelectric layer; a high acoustic velocity substrate provided on the side of the second surface of the piezoelectric layer; with The piezoelectric layer is made of crystal with a cut angle in which a plane perpendicular to the crystal Y axis is rotated around the crystal X axis, In a propagation direction that is 90° ⁇ 10° with respect to the crystal X-axis of the piezoelectric layer, the sound velocity of the high-sonic substrate is faster than the sound velocity of the piezoelectric layer,
  • the IDT electrode has a comb-shaped electrode having a plurality of electrode fingers aligned in the propagation direction.
  • FIG. 1 is a plan view schematically showing the configuration of a resonator in one embodiment
  • FIG. FIG. 2 is a cross-sectional view schematically showing the configuration of the resonator shown in FIG. 1; 2 is a diagram for explaining the crystal axis direction of the piezoelectric layer shown in FIG. 1;
  • FIG. FIG. 10 is a cross-sectional view schematically showing the configuration of a resonator in a modified example;
  • FIG. 10 is a cross-sectional view schematically showing the configuration of a resonator in a modified example;
  • 4 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the speed of sound in the first example.
  • 5 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the electromechanical coupling coefficient of the first example; 4 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the Q value of the first example. 4 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the primary frequency temperature coefficient of the first example. 5 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the secondary frequency temperature coefficient of the first example.
  • 4 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the third-order frequency temperature coefficient of the first embodiment; 4 is a graph showing frequency temperature characteristics of the first embodiment; 5 is a graph for explaining the effect of the sound velocity of the high sonic substrate of the first example on the Q value.
  • 8 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the speed of sound in the second example. 7 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the electromechanical coupling coefficient of the second embodiment; 9 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the Q value of the second example.
  • 10 is a graph showing the relationship between the rotation angle of the high acoustic velocity substrate and the electromechanical coupling coefficient of the third example. It is a graph which shows the rotation angle of the high-sonic-velocity board
  • FIG. 1 is a plan view schematically showing the configuration of a resonator in one embodiment.
  • FIG. 2 is a cross-sectional view schematically showing the structure of the resonator shown in FIG.
  • FIG. 3 is a diagram for explaining crystal axis directions of the piezoelectric layer shown in FIG.
  • the resonator 10 is a type of SAW resonator, and is an STW (Surface Transverse Wave) element that guides SSBW (Surface Skimming Bulk Wave). As shown in FIGS. 1 and 2, the resonator 10 includes a high acoustic velocity substrate 1, a low acoustic velocity layer 3, a piezoelectric layer 5, an IDT (Inter Digital Transducer) electrode 7, and a pair of reflectors 9. there is
  • the high acoustic velocity substrate 1 is a substrate that can suppress the vibration energy of the piezoelectric layer 5 from leaking as a bulk wave and reducing the Q value.
  • the high-sonic-velocity substrate 1 is, for example, a single-layer substrate in which the speed of sound (propagation speed of elastic waves) in the propagation direction PD is faster than the speed of sound in the propagation direction PD of the piezoelectric layer 5, as shown in FIG. .
  • the speed of sound in the propagation direction PD is also simply referred to as the "speed of sound”.
  • the sound velocity of the high-sonic-velocity substrate 1 is preferably 10% or more, more preferably 20% or more, and even more preferably 40% or more than the sound velocity of the piezoelectric layer 5 .
  • the high acoustic velocity substrate 1 is made of silicon single crystal, for example, but is not limited to this.
  • the high acoustic velocity substrate 1 is made of, for example, one of simple silicon (amorphous silicon, polycrystalline silicon, etc.), silicon compounds (silicon oxide, silicon nitride, silicon carbide, etc.), and aluminum compounds (aluminum nitride, aluminum oxide, etc.). may be formed.
  • the piezoelectric layer 5 is made of quartz crystal.
  • the sonic board 1 may also be made of quartz. In this case, the high acoustic velocity substrate 1 and the piezoelectric layer 5 may be made of quartz having different cut angles.
  • the crystal of the piezoelectric layer 5 is a BT cut described later, and is provided so that the crystal X axis is 90° ⁇ 10° with respect to the propagation direction PD, and the crystal of the high acoustic velocity substrate 1 is described later. It may be an AT cut, and may be provided so that the crystal X-axis is 90° ⁇ 10° with respect to the propagation direction PD.
  • the cut angle of the crystal forming the high acoustic velocity substrate 1 is not limited to the above as long as the sound velocity of the high acoustic velocity substrate 1 is sufficiently faster than the sound velocity of the piezoelectric layer 5 in the propagation direction PD.
  • the high acoustic velocity substrate 1 may be formed of crystal with a cut angle in which the plane orthogonal to the crystal Y axis is rotated counterclockwise in the range of 0° or more and 60° or less when viewed from the positive direction of the crystal X axis. good.
  • the high acoustic velocity substrate is not limited to the single layer structure shown in FIG. 2, and may have a multilayer structure.
  • the high sonic velocity substrate has a multilayer structure, if the sound velocity of the layer closest to the piezoelectric layer 5 in this multilayer structure is faster than the sound velocity of the piezoelectric layer 5, the sound velocity of the other layers of this multilayer structure is the sound velocity of the piezoelectric layer 5. It may be below. It is desirable that the layer closest to the piezoelectric layer 5 in the high sonic substrate having a multilayer structure has the same sonic speed as the high sonic substrate 1 described above, and is made of the same material as the high sonic substrate 1 described above. preferably
  • the high acoustic velocity substrate 1 preferably has mechanical strength capable of supporting a laminated structure including the low acoustic velocity layer 3 , the piezoelectric layer 5 , the IDT electrode 7 and the reflector 9 . Therefore, when the wavelength of the elastic wave is ⁇ , the thickness T1 of the high acoustic velocity substrate 1 is desirably 50 ⁇ or more, more desirably 100 ⁇ or more, and even more desirably 500 ⁇ or more.
  • the low sound velocity layer 3 is a layer for confining vibration energy, which has the property of concentrating in a low sound velocity medium, and suppressing leakage of the vibration energy from the piezoelectric layer 5 to the high sound velocity substrate 1 .
  • the low sound velocity layer 3 is a layer in which the sound velocity in the propagation direction PD is equal to or lower than the sound velocity in the propagation direction PD of the piezoelectric layer 5 .
  • the low acoustic velocity layer 3 is laminated directly on the high acoustic velocity substrate 1 .
  • Direct lamination is realized, for example, by direct bonding such as diffusion bonding or room temperature bonding, or direct film formation by PVD, CVD, or the like. At the boundaries between members in direct lamination, the composition ratio may change abruptly or gradually. The same applies to direct lamination on other layers and substrates.
  • the low sound velocity layer 3 is made of, for example, silicon oxide, which can improve the frequency temperature characteristics due to the temperature compensation effect.
  • the material of the low sound velocity layer 3 is not limited to silicon oxide, and may be formed of, for example, silicon oxynitride, tantalum oxide, or a compound obtained by adding fluorine, carbon, or boron to these.
  • the thickness T3 of the low sound velocity layer 3 is desirably set in the range of 0.01 ⁇ or more and 2.0 ⁇ or less, and more preferably set in the range of 0.1 ⁇ or more and 0.5 ⁇ or less. By setting the thickness T3 in the range of 2.0 ⁇ or less, the electromechanical coupling coefficient can be easily adjusted. Moreover, by setting the thickness T3 in the range of 0.01 ⁇ or more, leakage of vibration energy from the piezoelectric layer 5 can be sufficiently suppressed. Moreover, from the viewpoint of reducing warping of the resonator 10 due to the stress of the low sound velocity layer 3, the thickness T3 of the low sound velocity layer 3 is preferably 1/100 or less of the thickness T1 of the high sound velocity substrate 1. FIG. Note that the low sound velocity layer 3 may be omitted. That is, the piezoelectric layer 5 and the high acoustic velocity substrate 1 may be directly laminated.
  • the piezoelectric layer 5 is a layer that mutually converts electrical vibration energy and mechanical vibration energy and propagates the mechanical vibration energy as SSBW.
  • the piezoelectric layer 5 is laminated directly on the sound velocity layer 3 .
  • the piezoelectric layer 5 is made of crystal (rotated Y-cut crystal substrate) with a cut angle obtained by rotating a plane orthogonal to the crystal Y-axis about the crystal X-axis at a rotation angle ⁇ 1.
  • the piezoelectric layer 5 is provided so that the direction of 90° ⁇ 10° with respect to the crystal X-axis is the propagation direction PD.
  • the propagation direction PD is the direction along the Z'-axis obtained by rotating the crystal Z-axis around the crystal X-axis at the rotation angle ⁇ 1.
  • the rotation angle ⁇ 1 is positive (+) when viewed from the positive direction of the X axis of the crystal (from the front side to the back of the page of FIG. 3), negative (-) when clockwise, and 0. include.
  • the cut angles of the crystal are represented by Euler angles, they are (0°, ⁇ 1+90°, 90° ⁇ 10°).
  • the thickness T5 of the piezoelectric layer 5 is preferably set in the range of 0.02 ⁇ or more and 1.0 ⁇ or less, more preferably set in the range of 0.05 ⁇ or more and 0.5 ⁇ or less, and more preferably 0.1 ⁇ or more and 0.5 ⁇ or less. It is more desirable to set it in the range of 0.5 ⁇ or less. According to this, the electromechanical coupling coefficient can be easily adjusted in a wide range. Moreover, from the viewpoint of suppressing leakage of vibration energy from the piezoelectric layer 5, the thickness T5 of the piezoelectric layer 5 is preferably 1/100 or less of the thickness T1 of the high acoustic velocity substrate 1. FIG.
  • the IDT electrode 7 is a comb-shaped electrode.
  • the IDT electrode 7 has a pair of busbars 7a and a plurality of electrode fingers 7b.
  • the pair of bus bars 7a extend along the propagation direction PD and are arranged so as to be spaced apart from each other in a direction orthogonal to the propagation direction PD.
  • the plurality of electrode fingers 7b extend in a direction perpendicular to the propagation direction PD from each of the pair of busbars 7a and are arranged along the propagation direction PD.
  • a plurality of electrode fingers 7b extending from one bus bar 7a and a plurality of electrode fingers 7b extending from the other bus bar 7a are alternately arranged along the propagation direction PD.
  • the plurality of electrode fingers 7b extend in the crystal X-axis direction and rotate the crystal Z-axis about the crystal X-axis at a rotation angle ⁇ 1. are arranged along the Z'-axis direction.
  • the electrode period of the electrode fingers 7b determines the wavelength ⁇ of the elastic wave.
  • the edges on the ⁇ Z′-axis direction of two adjacent electrode fingers 7b electrically connected to each other are spaced apart in the Z′-axis direction by a distance ⁇ .
  • a pair of reflectors 9 are grating reflectors for reflecting SAW and improving the Q value.
  • a pair of reflectors 9 are arranged so as to sandwich the IDT electrode 7 in the propagation direction PD.
  • Each of the pair of reflectors 9 includes a pair of reflector busbars 9a each extending along the propagation direction PD and arranged so as to be spaced apart in directions orthogonal to the propagation direction PD. and arranged in the propagation direction PD.
  • the IDT electrode 7 and reflector 9 are provided on the piezoelectric layer 5 .
  • the IDT electrode 7 and the reflector 9 are made of, for example, a metal containing aluminum as a main component, but are not limited to this.
  • the IDT electrode 7 and reflector 9 may be made of, for example, copper, platinum, gold, silver, titanium, nickel, chromium, molybdenum, tungsten, or an alloy containing any of these metals as a main component.
  • the thickness T7 of the IDT electrode 7 and the reflector 9 is preferably set in the range of 0.01 ⁇ or more and 0.2 ⁇ or less, more preferably set in the range of 0.02 ⁇ or more and 0.15 ⁇ or less. More preferably, it is set in the range of 0.04 ⁇ or more and 1.0 ⁇ or less.
  • FIG. 4 and 5 are cross-sectional views schematically showing the configuration of a resonator in one modified example.
  • the high acoustic velocity substrate 1 and the piezoelectric layer 5 of the resonator 20 may be laminated directly on each other.
  • the sound velocity of the high sound velocity substrate 1 since the low sound velocity layer is omitted, in order to suppress the leakage of vibration energy from the piezoelectric layer 5 to the high sound velocity substrate 1, the sound velocity of the high sound velocity substrate 1 must be 20% lower than the sound velocity of the piezoelectric layer 5. % or more is desirable.
  • the high acoustic velocity substrate 31 of the resonator 30 may have a supporting substrate 31a and a high acoustic velocity layer 31b laminated on the supporting substrate 31a.
  • the high sound velocity layer 31b is, for example, directly laminated on the support substrate 31a, but is not limited to this, and may be laminated via a bonding member such as an adhesive.
  • the material of the supporting substrate 31a is not limited as long as it can support the laminated structure including the high acoustic velocity layer 31b, the low acoustic velocity layer 3, the piezoelectric layer 5, the IDT electrode 7 and the reflector 9.
  • the support substrate 31a may be made of a piezoelectric material such as sapphire, lithium tantalate, lithium niobate, quartz crystal, alumina, magnesia, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mullite, steatite, forsterite, or the like. It can be formed from various ceramics, dielectrics such as glass, semiconductors such as silicon and gallium nitride, and resin substrates.
  • the high acoustic velocity layer 31b is provided between the support substrate 31a and the low acoustic velocity layer 3.
  • the high acoustic velocity layer 31 b has a higher acoustic velocity in the propagation direction PD than the acoustic velocity in the propagation direction PD of the piezoelectric layer 5 .
  • the high acoustic velocity layer 31 b can be made of the same material as the high acoustic velocity substrate 1 . Leakage of vibration energy from the piezoelectric layer 5 can be suppressed as the thickness of the high sound velocity layer 31b increases. Therefore, the thickness of the high sound velocity layer 31b is desirably 0.5 ⁇ or more, and more desirably 1.5 ⁇ or more. However, from the viewpoint of manufacturability, the thickness of the high acoustic velocity layer 31b is preferably 10 ⁇ or less.
  • FIG. 6 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the speed of sound in the first example.
  • FIG. 7 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the electromechanical coupling coefficient of the first example.
  • FIG. 8 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the Q value of the first example.
  • the resonator 10 includes a high acoustic velocity substrate 1, a low acoustic velocity layer 3 laminated on the high acoustic velocity substrate 1, a piezoelectric layer 5 laminated on the low acoustic velocity layer 3, and a piezoelectric layer 5 and an IDT electrode 7 and a reflector 9 formed thereon.
  • High acoustic velocity substrate 1 silicon (single crystal)
  • T1 300 ⁇ m
  • Low sound velocity layer 3 Silicon oxide (amorphous)
  • T3 0.8 ⁇ m
  • Piezoelectric layer 5 crystal, Euler angles (0°, ⁇ 1+90°, 90°)
  • T5 2 ⁇ m
  • the resonator according to the comparative example is a resonator composed of a single piezoelectric layer 5 with the high acoustic velocity substrate 1 and the low acoustic velocity layer 3 omitted from the configuration of the first embodiment.
  • Various resonance characteristics were simulated in the first embodiment and the comparative example.
  • the horizontal axis of the graph in FIG. 6 indicates the rotation angle of piezoelectric layer ⁇ 1, and the vertical axis indicates the SAW sound velocity (Phase velocity) (unit: m/s).
  • the SAW sound velocity of the first example is higher than the SAW sound velocity of the comparative example. That is, within this range, the first embodiment is more advantageous than the comparative example in increasing the frequency.
  • the increase in SAW speed of sound is large.
  • the SAW sound velocity of the comparative example was 3300 m/s or less, while the SAW sound velocity of the first example increased to 3500 m/s or more.
  • the horizontal axis of the graph in FIG. 7 indicates the rotation angle of piezoelectric layer ⁇ 1, and the vertical axis indicates the electromechanical coupling coefficient (unit: %).
  • the electromechanical coupling coefficient of the first example is higher than the electromechanical coupling coefficient of the comparative example. That is, in this range, the first embodiment is superior to the comparative example in oscillation characteristics as an oscillator, and can be used as a filter in a wide band.
  • the horizontal axis of the graph in FIG. 8 indicates the rotation angle of piezoelectric layer ⁇ 1, and the vertical axis indicates the Q value (Q).
  • the Q value of the first example is higher than the Q value of the comparative example. That is, over the entire range of ⁇ 1, the first embodiment is superior to the comparative example in oscillation characteristics as an oscillator, can reduce phase noise, and can reduce insertion loss as a filter.
  • FIG. 9 is a graph showing the relationship between the rotation angle of the piezoelectric layer of the first embodiment and the primary frequency temperature coefficient.
  • FIG. 10 is a graph showing the relationship between the rotation angle of the piezoelectric layer of the first embodiment and the secondary frequency temperature coefficient.
  • FIG. 11 is a graph showing the relationship between the rotation angle of the piezoelectric layer of the first embodiment and the third-order frequency temperature coefficient.
  • FIG. 12 is a graph showing frequency temperature characteristics of the first embodiment.
  • the horizontal axis of the graph in FIG. 9 indicates the rotation angle of piezoelectric layer ⁇ 1, and the vertical axis indicates the 1st TCF (Temperature Coefficients of Frequency).
  • the unit of the vertical axis is ppm/K.
  • the horizontal axis of the graph in FIG. 10 indicates the rotation angle of piezoelectric layer ⁇ 1, and the vertical axis indicates the second frequency temperature coefficient (2nd TCF).
  • the units of the vertical axis are ppb/K2.
  • the horizontal axis of the graph in FIG. 11 indicates the rotation angle of piezoelectric layer ⁇ 1, and the vertical axis indicates the 3rd order frequency temperature coefficient (3rd TCF).
  • the unit of the vertical axis is ppt/ K3 .
  • the absolute value of the primary frequency temperature coefficient of the first example is smaller than the absolute value of the primary frequency temperature coefficient of the comparative example.
  • the second order frequency temperature coefficient and the third order frequency temperature coefficient are smaller than the absolute value of the primary frequency temperature coefficient of the comparative example.
  • the second order frequency temperature coefficient and the third order frequency temperature coefficient are smaller than the absolute value of the primary frequency temperature coefficient of the comparative example.
  • the third-order frequency temperature coefficient of the comparative example was 80 ppt/K 3 or more, while the absolute value of the third-order frequency temperature coefficient of the first embodiment was 40 ppt/K 3 or less. was reduced to
  • the horizontal axis of the graph in FIG. 12 indicates temperature (unit: °C), and the vertical axis indicates frequency variation (dF) (unit: ppm) based on the frequency at 25°C.
  • the frequency temperature characteristic of the first example is superior to that of the comparative example.
  • FIG. 13 is a graph for explaining the effect of the sound velocity of the high acoustic velocity substrate of the first embodiment on the Q value.
  • changes in the Q value obtained by a simulation in which the sound velocity of the high-sonic-velocity substrate 1 is changed are shown.
  • the horizontal axis of the graph in FIG. 13 indicates the sound velocity (Phase velocity of substrate) (unit: m/s) of the high-sonic substrate 1, and the vertical axis indicates the Q value.
  • the Q value is increased. ing.
  • FIG. 14 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the speed of sound in the second example.
  • FIG. 15 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the electromechanical coupling coefficient of the second example.
  • FIG. 16 is a graph showing the relationship between the rotation angle of the piezoelectric layer and the Q value of the second example.
  • the second embodiment differs from the first embodiment in that the low sound velocity layer 3 is omitted and the piezoelectric layer 5 is directly bonded to the high sound velocity substrate 1 .
  • the configuration is the same as that of the first embodiment.
  • the horizontal axis of the graph in FIG. 14 indicates the rotation angle of piezoelectric layer ⁇ 1, and the vertical axis indicates the SAW sound velocity (Phase velocity) (unit: m/s).
  • the SAW sound velocity of the second example is higher than the SAW sound velocity of the comparative example.
  • the increase in SAW speed of sound is large.
  • the SAW sound velocity of the comparative example was 3300 m/s or less, while the SAW sound velocity of the second example increased to 4200 m/s or more.
  • the SAW sound velocity of the second embodiment is greater than the SAW sound velocity of the first embodiment over the entire range of ⁇ 1.
  • the horizontal axis of the graph in FIG. 15 indicates the rotation angle of piezoelectric layer ⁇ 1, and the vertical axis indicates the electromechanical coupling coefficient (unit: %).
  • the electromechanical coupling coefficient of the second example is higher than the electromechanical coupling coefficient of the comparative example.
  • the increase in the electromechanical coupling coefficient is large.
  • the electromechanical coupling coefficient of the comparative example was 2.5% or less, while the electromechanical coupling coefficient of the second example increased to 3.8% or more.
  • the electromechanical coupling coefficient of the second embodiment is larger than the electromechanical coupling coefficient of the first embodiment.
  • the horizontal axis of the graph in FIG. 16 indicates the rotation angle of piezoelectric layer ⁇ 1, and the vertical axis indicates the Q value (Q).
  • the Q value of the second example is higher than the Q value of the comparative example.
  • the Q value increases significantly.
  • the Q value of the comparative example was 1000 or less, while the Q value of the second example increased to 8000 or more. Note that the Q value of the first embodiment is larger than the Q value of the second embodiment over the entire range of ⁇ 1.
  • FIG. 17 is a graph showing the relationship between the rotation angle of the high acoustic velocity substrate and the speed of sound in the third embodiment.
  • FIG. 18 is a graph showing the relationship between the rotation angle of the high acoustic velocity substrate and the electromechanical coupling coefficient of the third embodiment.
  • FIG. 19 is a graph showing the relationship between the rotation angle and the Q value of the high acoustic velocity substrate of the third example.
  • FIG. 20 is a graph showing the relationship between the rotation angle of the high acoustic velocity substrate and the primary frequency temperature coefficient of the third embodiment.
  • FIG. 21 is a graph showing the relationship between the rotation angle of the high acoustic velocity substrate and the secondary frequency temperature coefficient of the third embodiment.
  • FIG. 22 is a graph showing the relationship between the rotation angle of the high-sonic substrate of the third embodiment and the third-order frequency temperature coefficient.
  • the third embodiment differs from the second embodiment in that the high acoustic velocity substrate 1 is made of quartz. Other than that, the configuration is the same as that of the second embodiment.
  • the high acoustic velocity substrate 1 is a quartz crystal whose plane perpendicular to the crystal Y axis is rotated around the crystal X axis at a rotation angle ⁇ 2, and the crystal X axes of the piezoelectric layer 5 and the high acoustic velocity substrate 1 are parallel to each other. It is laminated like this.
  • the cut angle of the crystal of the high acoustic velocity substrate 1 is represented by Euler angles, it is expressed as (0°, ⁇ 2 ⁇ 90°, 90°).
  • the change in resonance characteristic or temperature characteristic is simulated. did.
  • a comparative example is a resonator using, as a piezoelectric layer, a high acoustic velocity substrate made of a single-layer crystal indicated by Euler angles (0°, ⁇ 2 ⁇ 90°, 90°). Therefore, the rotation angle .theta.2 in the comparative example corresponds to the rotation angle .theta.1 in the third embodiment.
  • a simulation was performed of changes in resonance characteristics or temperature characteristics when the rotation angle ⁇ 2 was changed.
  • the horizontal axis of the graph in FIG. 17 indicates the rotation angle of substrate ⁇ 2, and the vertical axis indicates the SAW sound velocity (Phase velocity) (unit: m/s).
  • the horizontal axis of the graph in FIG. 18 indicates the rotation angle of substrate ⁇ 2 of the high acoustic velocity substrate, and the vertical axis indicates the electromechanical coupling coefficient (unit: %).
  • the horizontal axis of the graph in FIG. 19 indicates the rotation angle of substrate ⁇ 2 of the high acoustic velocity substrate, and the vertical axis indicates the Q value (Q).
  • the horizontal axis of the graph in FIG. 20 indicates the rotation angle of substrate ⁇ 2 of the high acoustic velocity substrate, and the vertical axis indicates the first frequency temperature coefficient (1st TCF).
  • the horizontal axis of the graph of FIG. 21 indicates the rotation angle of substrate ⁇ 2 of the high acoustic velocity substrate, and the vertical axis indicates the secondary frequency temperature coefficient (2nd TCF).
  • the horizontal axis of the graph in FIG. 22 indicates the rotation angle of substrate ⁇ 2 of the high acoustic velocity substrate, and the vertical axis indicates the third order frequency temperature coefficient (3rd TCF).
  • a resonator includes a piezoelectric layer having a first surface and a second surface facing each other, an IDT electrode provided on the side of the first surface of the piezoelectric layer, and a second surface of the piezoelectric layer.
  • a high acoustic velocity substrate provided on the side of the crystal plane, wherein the piezoelectric layer is made of crystal with a cut angle in which a plane orthogonal to the crystal Y axis is rotated around the crystal X axis, and the piezoelectric layer is cut with respect to the crystal X axis.
  • the sound velocity of the high acoustic velocity substrate is faster than the sound velocity of the piezoelectric layer in the propagation direction of 90° ⁇ 10°, and the IDT electrode has a comb-shaped electrode having a plurality of electrode fingers arranged in the propagation direction.
  • a resonator having at least a third-order frequency temperature coefficient and a Q value superior to those of a resonator made of a single piezoelectric layer is provided. Furthermore, by appropriately selecting the rotation angle for rotating the crystal plane of the piezoelectric layer perpendicular to the crystal Y-axis around the crystal X-axis, the electromechanical coupling coefficient, the SAW sound velocity, the primary frequency temperature coefficient and the secondary frequency temperature coefficient can be improved.
  • the piezoelectric layer has a cut angle obtained by rotating a plane perpendicular to the crystal Y-axis counterclockwise within a range of ⁇ 59° ⁇ 10° as viewed from the positive direction of the crystal X-axis.
  • a resonator that is superior in SAW sound velocity and electromechanical coupling coefficient to a resonator made up of a single piezoelectric layer is provided.
  • the piezoelectric layer has a cut angle obtained by rotating a plane orthogonal to the crystal Y-axis counterclockwise within a range of 35° ⁇ 10° as viewed from the positive direction of the crystal X-axis. It may be made of crystal.
  • the piezoelectric layer and the high acoustic velocity substrate may be laminated directly.
  • a low acoustic velocity layer may be provided between the piezoelectric layer and the high acoustic velocity substrate, and the acoustic velocity of the low acoustic velocity layer may be equal to or lower than the acoustic velocity of the piezoelectric layer in the propagation direction.
  • the thickness of the low sound velocity layer may be set in the range of 0.1 ⁇ or more and 0.5 ⁇ or less, where ⁇ is the wavelength of the elastic wave determined by the electrode period of the IDT electrodes.
  • the thickness of the low acoustic velocity layer may be 1/100 or less of the thickness of the high acoustic velocity substrate.
  • the thickness of the piezoelectric layer may be set in the range of 0.05 ⁇ or more and 0.5 ⁇ or less, where ⁇ is the wavelength of the elastic wave determined by the electrode period of the IDT electrodes.
  • the thickness of the piezoelectric layer may be 1/100 or less of the thickness of the high acoustic velocity substrate.
  • the sound velocity of the high acoustic velocity substrate may be 20% or more higher than the sound velocity of the piezoelectric layer in the propagation direction.
  • the sound velocity of the high acoustic velocity substrate may be 40% or more higher than the sound velocity of the piezoelectric layer in the propagation direction.
  • the high acoustic velocity substrate may be made of any one of silicon, silicon compounds and aluminum compounds.
  • the high acoustic velocity substrate may be made of single crystal silicon.
  • the high acoustic velocity substrate is cut by rotating a plane orthogonal to the crystal Y axis counterclockwise within a range of 0° or more and 60° or less when viewed from the positive direction of the crystal X axis.
  • the piezoelectric layer and the high acoustic velocity substrate may be made of angular quartz and arranged such that their crystal X-axes are parallel to each other.
  • the IDT electrode may be made of a metal containing aluminum as a main component.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)
PCT/JP2021/039760 2021-04-20 2021-10-28 共振子 Ceased WO2022224470A1 (ja)

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DE212021000552.7U DE212021000552U1 (de) 2021-04-20 2021-10-28 Resonator
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CN118337167A (zh) * 2024-04-10 2024-07-12 无锡市好达电子股份有限公司 弹性波装置

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US12483221B2 (en) 2021-07-15 2025-11-25 Skyworks Solutions, Inc. Multilayer piezoelectric substrate device with partially recessed passivation layer
US12542524B2 (en) * 2022-04-08 2026-02-03 Skyworks Solutions, Inc. Acoustic wave device with trench portions and narrow interdigital transducer tip portions for transverse mode suppression

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JP7080671B2 (ja) 2018-02-27 2022-06-06 ＮＤＫ ＳＡＷ ｄｅｖｉｃｅｓ株式会社 弾性表面波デバイス

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JP2006191330A (ja) * 2005-01-06 2006-07-20 Epson Toyocom Corp 弾性表面波デバイス
WO2019138812A1 (ja) * 2018-01-12 2019-07-18 株式会社村田製作所 弾性波装置、マルチプレクサ、高周波フロントエンド回路、及び通信装置
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CN118337167A (zh) * 2024-04-10 2024-07-12 无锡市好达电子股份有限公司 弹性波装置

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JP7587766B2 (ja) 2024-11-21
DE212021000552U1 (de) 2023-11-07

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