WO2023167316A1 - Elastic wave device - Google Patents

Elastic wave device Download PDF

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Publication number
WO2023167316A1
WO2023167316A1 PCT/JP2023/008059 JP2023008059W WO2023167316A1 WO 2023167316 A1 WO2023167316 A1 WO 2023167316A1 JP 2023008059 W JP2023008059 W JP 2023008059W WO 2023167316 A1 WO2023167316 A1 WO 2023167316A1
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electrode
elastic wave
wave device
piezoelectric layer
electrodes
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PCT/JP2023/008059
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French (fr)
Japanese (ja)
Inventor
克也 大門
明洋 井山
昌和 三村
和則 井上
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株式会社村田製作所
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Publication of WO2023167316A1 publication Critical patent/WO2023167316A1/en

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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
    • H03H9/25—Constructional features of resonators using surface acoustic waves

Definitions

  • the present disclosure relates to an acoustic wave device including a piezoelectric layer (piezoelectric layer).
  • Patent Document 1 discloses an elastic wave device that uses plate waves.
  • An acoustic wave device described in Patent Document 1 includes a support, a piezoelectric substrate, and an IDT electrode.
  • the support is provided with a cavity.
  • a piezoelectric substrate is provided on the support so as to overlap the cavity.
  • the IDT electrode is provided on the piezoelectric substrate so as to overlap the cavity.
  • plate waves are excited by IDT electrodes.
  • the edge of the cavity does not include a straight portion extending parallel to the propagation direction of the Lamb waves excited by the IDT electrodes.
  • An object of the present disclosure is to provide an elastic wave device capable of maintaining good return loss while preventing deformation of the membrane portion.
  • An elastic wave device includes: a support substrate; a piezoelectric layer provided on the support substrate; a functional electrode provided on the piezoelectric layer; a hollow portion provided inside the support substrate and overlapping with a part of the functional electrode in a plan view along the stacking direction of the support substrate and the piezoelectric layer; a first member and a second member provided in the cavity in a direction intersecting the stacking direction with a gap therebetween and supporting the piezoelectric layers in the stacking direction;
  • the functional electrode is Having a plurality of electrode fingers spaced apart along a direction intersecting the stacking direction, When viewed along the stacking direction, the number of electrode fingers positioned between the first member and the second member is 10 or more.
  • an elastic wave device capable of maintaining good return loss while preventing deformation of the membrane portion.
  • FIG. 1 is a schematic perspective view showing the appearance of elastic wave devices of first and second aspects
  • FIG. FIG. 4 is a plan view showing an electrode structure on the piezoelectric layer; Sectional drawing of the part which follows the AA line in FIG. 1A.
  • FIG. 2 is a schematic front cross-sectional view for explaining Lamb waves propagating through a piezoelectric film of a conventional elastic wave device.
  • FIG. 2 is a schematic front cross-sectional view for explaining waves of the elastic wave device of the present disclosure;
  • FIG. 4 is a schematic diagram showing a bulk wave when a voltage is applied between the first electrode and the second electrode so that the potential of the second electrode is higher than that of the first electrode.
  • FIG. 3 is a diagram showing resonance characteristics of an elastic wave device according to an embodiment of the present disclosure;
  • FIG. 4 is a diagram showing the relationship between d/2p and the fractional bandwidth as a resonator of an acoustic wave device; The top view of another elastic wave device concerning one embodiment of this indication.
  • FIG. 2 is a reference diagram showing an example of resonance characteristics of an elastic wave device;
  • FIG. 4 is a diagram showing the relationship between the fractional bandwidth and the amount of phase rotation of the spurious impedance normalized by 180 degrees as the magnitude of the spurious when a large number of acoustic wave resonators are configured; 4 is a diagram showing the relationship between d/2p, metallization ratio MR, and fractional bandwidth;
  • FIG. 4 is a diagram showing a map of the fractional bandwidth with respect to the Euler angles (0°, ⁇ , ⁇ ) of LiNbO 3 when d/p is infinitely close to 0; 1 is a partially cutaway perspective view for explaining an elastic wave device according to an embodiment of the present disclosure;
  • FIG. 1 is a plan view showing an elastic wave device according to an embodiment of the present disclosure;
  • FIG. 4 is a partial perspective view of an elastic wave device for explaining the relationship between return loss and the number of electrode fingers of a functional electrode;
  • Graph showing the relationship between return loss and frequency. 4 is a graph showing the relationship between return loss and the number of electrode fingers of a functional electrode;
  • the top view which shows the 1st modification of the elastic wave apparatus of FIG.
  • Elastic wave devices include, for example, a piezoelectric layer made of lithium niobate or lithium tantalate, first electrodes facing each other in a direction intersecting the thickness direction of the piezoelectric layer, and and a second electrode.
  • the first electrode and the second electrode are adjacent electrodes, the thickness of the piezoelectric layer is d, and the distance between the centers of the first electrode and the second electrode is p.
  • d/p is 0.5 or less.
  • Lamb waves are used as plate waves. Then, resonance characteristics due to the Lamb wave can be obtained.
  • An acoustic wave device includes a piezoelectric layer made of lithium niobate or lithium tantalate, and an upper electrode and a lower electrode facing each other in the thickness direction of the piezoelectric layer with the piezoelectric layer interposed therebetween.
  • FIG. 1A is a schematic perspective view showing the appearance of an acoustic wave device according to one embodiment of the first and second aspects
  • FIG. 1B is a plan view showing an electrode structure on a piezoelectric layer
  • 2 is a cross-sectional view of a portion taken along line AA in FIG. 1A.
  • the acoustic wave device 1 has a piezoelectric layer 2 made of LiNbO 3 .
  • the piezoelectric layer 2 may consist of LiTaO 3 .
  • the cut angle of LiNbO 3 and LiTaO 3 is Z-cut in this embodiment, but may be rotational Y-cut or X-cut.
  • the Y-propagation and X-propagation ⁇ 30° propagation orientations are preferred.
  • the thickness of the piezoelectric layer 2 is not particularly limited, it is preferably 50 nm or more and 1000 nm or less in order to effectively excite the thickness-shear primary mode.
  • the piezoelectric layer 2 has first and second main surfaces 2a and 2b facing each other. Electrodes 3 and 4 are provided on the first main surface 2a.
  • the electrode 3 is an example of the "first electrode” and the electrode 4 is an example of the "second electrode”.
  • the multiple electrodes 3 are multiple first electrode fingers connected to a first busbar 5 .
  • the multiple electrodes 4 are multiple second electrode fingers connected to the second bus bar 6 .
  • the plurality of electrodes 3 and the plurality of electrodes 4 are interleaved with each other.
  • the electrodes 3 and 4 have a rectangular shape and a length direction.
  • the electrode 3 and the adjacent electrode 4 face each other in a direction perpendicular to the length direction.
  • These electrodes 3 and 4, the first bus bar 5 and the second bus bar 6 constitute an IDT (Interdigital Transducer) electrode.
  • IDT Interdigital Transducer
  • Both the length direction of the electrodes 3 and 4 and the direction orthogonal to the length direction of the electrodes 3 and 4 are directions crossing the thickness direction of the piezoelectric layer 2 . Therefore, it can be said that the electrode 3 and the adjacent electrode 4 face each other in the direction intersecting the thickness direction of the piezoelectric layer 2 .
  • the length direction of the electrodes 3 and 4 may be interchanged with the direction orthogonal to the length direction of the electrodes 3 and 4 shown in FIGS. 1A and 1B. That is, in FIGS. 1A and 1B, the electrodes 3 and 4 may extend in the direction in which the first busbar 5 and the second busbar 6 extend. In that case, the first busbar 5 and the second busbar 6 extend in the direction in which the electrodes 3 and 4 extend in FIGS. 1A and 1B.
  • a plurality of pairs of structures in which an electrode 3 connected to one potential and an electrode 4 connected to the other potential are adjacent to each other are provided in a direction perpendicular to the length direction of the electrodes 3 and 4.
  • the electrodes 3 and 4 are adjacent to each other, it does not mean that the electrodes 3 and 4 are arranged so as to be in direct contact with each other, but that the electrodes 3 and 4 are arranged with a gap therebetween.
  • the electrode 3 and the electrode 4 are adjacent to each other, no electrode connected to the hot electrode or the ground electrode, including the other electrodes 3 and 4, is arranged between the electrode 3 and the electrode 4.
  • the logarithms need not be integer pairs, but may be 1.5 pairs, 2.5 pairs, or the like.
  • the center-to-center distance or pitch between the electrodes 3 and 4 is preferably in the range of 1 ⁇ m or more and 10 ⁇ m or less. Further, the center-to-center distance between the electrodes 3 and 4 means the center of the width dimension of the electrode 3 in the direction perpendicular to the length direction of the electrode 3 and the width dimension of the electrode 4 in the direction perpendicular to the length direction of the electrode 4.
  • the center-to-center distance between the electrodes 3 and 4 is 1. .
  • the width of the electrodes 3 and 4, that is, the dimension in the facing direction of the electrodes 3 and 4 is preferably in the range of 150 nm or more and 1000 nm or less.
  • center-to-center distance between the electrodes 3 and 4 means the distance between the center of the dimension (width dimension) of the electrode 3 in the direction orthogonal to the length direction of the electrode 3 and the distance between the center of the electrode 4 in the direction orthogonal to the length direction of the electrode 4. It is the distance connecting the center of the dimension (width dimension) of
  • the direction perpendicular to the length direction of the electrodes 3 and 4 is the direction perpendicular to the polarization direction of the piezoelectric layer 2 .
  • “perpendicular” is not limited to being strictly perpendicular, but substantially perpendicular (the angle formed by the direction perpendicular to the length direction of the electrodes 3 and 4 and the polarization direction is, for example, 90° ⁇ 10°). It's okay.
  • a supporting member 8 is laminated on the second main surface 2b side of the piezoelectric layer 2 with an insulating layer 7 interposed therebetween.
  • the insulating layer 7 and the support member 8 have a frame shape and, as shown in FIG. 2, have openings 7a and 8a.
  • a cavity 9 is thereby formed.
  • the cavity 9 is provided so as not to disturb the vibration of the excitation region C of the piezoelectric layer 2 . Therefore, the support member 8 is laminated on the second main surface 2b with the insulating layer 7 interposed therebetween at a position not overlapping the portion where at least one pair of electrodes 3 and 4 are provided. Note that the insulating layer 7 may not be provided. Therefore, the support member 8 can be directly or indirectly laminated to the second main surface 2b of the piezoelectric layer 2 .
  • the insulating layer 7 is made of silicon oxide. However, in addition to silicon oxide, suitable insulating materials such as silicon oxynitride and alumina can be used.
  • the support member 8 is made of Si. The plane orientation of the surface of Si on the piezoelectric layer 2 side may be (100), (110), or (111). Preferably, high-resistance Si having a resistivity of 4 k ⁇ or more is desirable. However, the supporting member 8 can also be constructed using an appropriate insulating material or semiconductor material.
  • Materials for the support member 8 include, for example, aluminum oxide, lithium tantalate, lithium niobate, piezoelectric materials such as crystal, alumina, magnesia, sapphire, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mullite, and steer.
  • Various ceramics such as tight and forsterite, dielectrics such as diamond and glass, and semiconductors such as gallium nitride can be used.
  • the plurality of electrodes 3, 4 and the first and second bus bars 5, 6 are made of appropriate metals or alloys such as Al, AlCu alloys.
  • the electrodes 3 and 4 and the first and second bus bars 5 and 6 have a structure in which an Al film is laminated on a Ti film. Note that an adhesion layer other than the Ti film may be used.
  • an AC voltage is applied between the multiple electrodes 3 and the multiple electrodes 4 . More specifically, an AC voltage is applied between the first busbar 5 and the second busbar 6 . As a result, it is possible to obtain resonance characteristics using a thickness-shear primary mode bulk wave excited in the piezoelectric layer 2 .
  • d/p is 0.0, where d is the thickness of the piezoelectric layer 2 and p is the center-to-center distance between any one of the pairs of electrodes 3 and 4 adjacent to each other. 5 or less.
  • d/p is 0.24 or less, in which case even better resonance characteristics can be obtained.
  • the center-to-center distance p of the electrodes 3 and 4 is the average distance between the center-to-center distances of each adjacent electrode 3 and 4 .
  • the elastic wave device 1 of the present embodiment has the above configuration, even if the logarithm of the electrodes 3 and 4 is reduced in order to reduce the size, the Q value is unlikely to decrease. This is because the resonator does not require reflectors on both sides, and the propagation loss is small. The reason why the above reflector is not required is that the bulk wave of the thickness-shlip primary mode is used.
  • FIG. 3A is a schematic front cross-sectional view for explaining Lamb waves propagating through a piezoelectric film of a conventional elastic wave device.
  • a conventional elastic wave device is described, for example, in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2012-257019).
  • FIG. 3A in the conventional acoustic wave device, waves propagate through the piezoelectric film 201 as indicated by arrows.
  • the first main surface 201a and the second main surface 201b face each other, and the thickness direction connecting the first main surface 201a and the second main surface 201b is the Z direction. is.
  • the X direction is the direction in which the electrode fingers of the IDT electrodes are arranged.
  • the wave propagates in the X direction as shown. Since it is a plate wave, although the piezoelectric film 201 as a whole vibrates, since the wave propagates in the X direction, reflectors are arranged on both sides to obtain resonance characteristics. Therefore, a wave propagation loss occurs, and the Q value decreases when miniaturization is attempted, that is, when the logarithm of the electrode fingers is decreased.
  • the wave is generated between the first main surface 2a and the second main surface 2a of the piezoelectric layer 2. It propagates almost in the direction connecting the surface 2b, that is, in the Z direction, and resonates. That is, the X-direction component of the wave is significantly smaller than the Z-direction component. Further, since resonance characteristics are obtained by propagating waves in the Z direction, no reflector is required. Therefore, no propagation loss occurs when propagating to the reflector. Therefore, even if the number of electrode pairs consisting of the electrodes 3 and 4 is reduced in an attempt to promote miniaturization, the Q value is unlikely to decrease.
  • the amplitude direction of the bulk wave of the primary thickness-shear mode is defined by the first region 451 included in the excitation region C of the piezoelectric layer 2 and the second region 452 included in the excitation region C.
  • FIG. 4 schematically shows bulk waves when a voltage is applied between the electrodes 3 and 4 so that the potential of the electrode 4 is higher than that of the electrode 3 .
  • the first region 451 is a region of the excitation region C between the first main surface 2a and a virtual plane VP1 that is perpendicular to the thickness direction of the piezoelectric layer 2 and bisects the piezoelectric layer 2 .
  • the second region 452 is a region of the excitation region C between the virtual plane VP1 and the second main surface 2b.
  • At least one pair of electrodes consisting of the electrodes 3 and 4 is arranged. It is not always necessary to have a plurality of pairs of electrode pairs. That is, it is sufficient that at least one pair of electrodes is provided.
  • the electrode 3 is an electrode connected to a hot potential
  • the electrode 4 is an electrode connected to a ground potential.
  • electrode 3 may also be connected to ground potential and electrode 4 to hot potential.
  • at least one pair of electrodes is an electrode connected to a hot potential or an electrode connected to a ground potential, as described above, and no floating electrodes are provided.
  • FIG. 5 is a diagram showing resonance characteristics of an acoustic wave device according to an embodiment of the present disclosure.
  • the design parameters of the elastic wave device 1 with this resonance characteristic are as follows.
  • the number of pairs of electrodes 3 and 4 21 pairs
  • center distance between electrodes 3 ⁇ m
  • width of electrodes 3 and 4 500 nm
  • d/p 0.133.
  • Insulating layer 7 Silicon oxide film with a thickness of 1 ⁇ m.
  • Support member 8 Si.
  • the length of the excitation region C is the dimension along the length direction of the electrodes 3 and 4 of the excitation region C.
  • the inter-electrode distances of the electrode pairs consisting of the electrodes 3 and 4 are all the same in a plurality of pairs. That is, the electrodes 3 and 4 were arranged at equal pitches.
  • d/p is more preferably 0.5 or less, as described above. is less than or equal to 0.24. This will be explained with reference to FIG.
  • FIG. 6 is a diagram showing the relationship between this d/2p and the fractional bandwidth of the acoustic wave device as a resonator.
  • a resonator with a wider specific band can be obtained, and a resonator with a higher coupling coefficient can be realized. Therefore, like the elastic wave device of the second aspect of the present disclosure, by setting d/p to 0.5 or less, a resonator having a high coupling coefficient that utilizes the bulk wave of the primary thickness shear mode can be constructed.
  • At least one pair of electrodes may be one pair, and p is the center-to-center distance between adjacent electrodes 3 and 4 in the case of one pair of electrodes. In the case of 1.5 pairs or more of electrodes, the average distance between the centers of adjacent electrodes 3 and 4 should be p.
  • the thickness d of the piezoelectric layer if the piezoelectric layer 2 has variations in thickness, a value obtained by averaging the thickness may be adopted.
  • FIG. 7 is a plan view of another elastic wave device according to one embodiment of the present disclosure.
  • a pair of electrodes having electrode 3 and electrode 4 is provided on first main surface 2 a of piezoelectric layer 2 .
  • K in FIG. 7 is the intersection width.
  • the number of pairs of electrodes may be one. Even in this case, if the above d/p is 0.5 or less, it is possible to effectively excite the bulk wave in the primary mode of thickness shear.
  • the adjacent electrodes 3 and 4 with respect to the excitation region, which is an overlapping region when viewed in the direction in which any of the adjacent electrodes 3 and 4 face each other. It is desirable that the metallization ratio MR of the electrodes 3 and 4 satisfy MR ⁇ 1.75(d/p)+0.075. That is, when viewed in the direction in which the plurality of adjacent first electrode fingers and the plurality of second electrode fingers face each other, the region where the plurality of first electrode fingers and the plurality of second electrode fingers overlap is excited.
  • MR is the metallization ratio of the plurality of first electrode fingers and the plurality of second electrode fingers to the excitation region. MR ⁇ 1.75(d/p)+0.075. preferably fulfilled. In that case, spurious can be effectively reduced.
  • FIG. 8 is a reference diagram showing an example of resonance characteristics of the acoustic wave device 1.
  • a spurious signal indicated by an arrow B appears between the resonance frequency and the anti-resonance frequency.
  • d/p 0.08 and the Euler angles of LiNbO 3 (0°, 0°, 90°).
  • the metallization ratio MR was set to 0.35.
  • the metallization ratio MR will be explained with reference to FIG. 1B.
  • the excitation region means a region where the electrode 3 and the electrode 4 overlap each other when the electrodes 3 and 4 are viewed in a direction orthogonal to the length direction of the electrodes 3 and 4, that is, in a facing direction. and a region where the electrodes 3 and 4 in the region between the electrodes 3 and 4 overlap.
  • the area of the electrodes 3 and 4 in the excitation region C with respect to the area of this excitation region is the metallization ratio MR. That is, the metallization ratio MR is the ratio of the area of the metallization portion to the area of the drive region.
  • MR may be the ratio of the metallization portion included in the entire excitation region to the total area of the excitation region.
  • FIG. 9 is a diagram showing the relationship between the fractional bandwidth and the amount of phase rotation of the spurious impedance normalized by 180 degrees as the magnitude of the spurious when a large number of acoustic wave resonators are configured according to this embodiment. be.
  • the ratio band was adjusted by changing the film thickness of the piezoelectric layer and the dimensions of the electrodes.
  • FIG. 9 shows the results when a Z-cut LiNbO 3 piezoelectric layer is used, but the same tendency is obtained when piezoelectric layers with other cut angles are used.
  • the spurious is as large as 1.0.
  • the fractional band exceeds 0.17, that is, when it exceeds 17%, a large spurious with a spurious level of 1 or more changes the parameters constituting the fractional band, even if the passband appear within. That is, as in the resonance characteristics shown in FIG. 8, a large spurious component indicated by arrow B appears within the band. Therefore, the specific bandwidth is preferably 17% or less. In this case, by adjusting the film thickness of the piezoelectric layer 2 and the dimensions of the electrodes 3 and 4, the spurious response can be reduced.
  • FIG. 10 is a diagram showing the relationship between d/2p, metallization ratio MR, and fractional bandwidth.
  • various elastic wave devices having different d/2p and MR were constructed, and the fractional bandwidth was measured.
  • the hatched portion on the right side of the dashed line D in FIG. 10 is the area where the fractional bandwidth is 17% or less.
  • FIG. 11 is a diagram showing a map of fractional bandwidth with respect to Euler angles (0°, ⁇ , ⁇ ) of LiNbO 3 when d/p is brought infinitely close to 0.
  • the hatched portion in FIG. 11 is a region where a fractional bandwidth of at least 5% or more is obtained, and when the range of the region is approximated, the following formulas (1), (2) and (3) ).
  • the fractional band can be sufficiently widened, which is preferable.
  • FIG. 12 is a partially cutaway perspective view for explaining an elastic wave device according to a modification of one embodiment of the present disclosure.
  • the elastic wave device 81 has a support substrate 82 .
  • the support substrate 82 is provided with a concave portion that is open on the upper surface.
  • a piezoelectric layer 83 is laminated on the support substrate 82 .
  • a hollow portion 9 is thereby formed.
  • An IDT electrode 84 is provided on the piezoelectric layer 83 above the cavity 9 .
  • Reflectors 85 and 86 are provided on both sides of the IDT electrode 84 in the elastic wave propagation direction.
  • the outer periphery of the hollow portion 9 is indicated by broken lines.
  • the IDT electrode 84 has first and second bus bars 84a and 84b, an electrode 84c as a plurality of first electrode fingers and an electrode 84d as a plurality of second electrode fingers.
  • the multiple electrodes 84c are connected to the first bus bar 84a.
  • the multiple electrodes 84d are connected to the second bus bar 84b.
  • the multiple electrodes 84c and the multiple electrodes 84d are interposed.
  • a Lamb wave as a plate wave is excited by applying an AC electric field to the IDT electrodes 84 on the cavity 9. Since the reflectors 85 and 86 are provided on both sides, the resonance characteristics due to the Lamb wave can be obtained.
  • the elastic wave device of the present disclosure may utilize plate waves.
  • FIG. 13 and 14 An elastic wave device 1 according to an embodiment of the present disclosure will be described with reference to FIGS. 13 and 14.
  • FIG. 13 and 14 the description of the content overlapping with the elastic wave devices of the first to fourth aspects will be omitted as appropriate.
  • the contents described below for the elastic wave devices of the first to fourth aspects can be applied.
  • the acoustic wave device 1 includes a support substrate 110, a piezoelectric layer 2, and functional electrodes 120.
  • the support substrate 110 is composed only of the support member 8, for example.
  • the piezoelectric layer 2 is provided on the support member 8 .
  • a functional electrode 120 is provided on the piezoelectric layer 2 .
  • a hollow portion 9 is provided inside the support substrate 110 .
  • the hollow portion 9 is provided at a position overlapping with a portion of the functional electrode 120 in plan view along the stacking direction (for example, Z direction) of the support substrate 110 and the piezoelectric layer 2 .
  • a first member 141 and a second member 142 are provided in the hollow portion 9 with a gap therebetween in a first direction (for example, the X direction) intersecting the stacking direction Z in the hollow portion 9 .
  • Each of the first member 141 and the second member 142 is configured to support the piezoelectric layer 2 in the stacking direction Z and prevent deformation of the membrane portion 21, which will be described later.
  • each of the first member 141 and the second member 142 has a substantially quadrangular prism shape extending in a second direction (eg, Y direction) that intersects the stacking direction Z and the first direction X. As shown in FIG.
  • the piezoelectric layer 2 has a membrane portion 21 .
  • the membrane part 21 constitutes a part of the piezoelectric layer 2 that at least partially overlaps the hollow part 9 in the stacking direction Z, for example.
  • a functional electrode 120 is positioned on the membrane portion 21 to form an excitation region. That is, the first member 141 and the second member 142 are arranged in the hollow portion 9 so as to overlap with the excitation region when viewed along the stacking direction Z. As shown in FIG.
  • the functional electrode 120 is, for example, an IDT electrode having a plurality of electrode fingers 121 and 122, and is positioned between two wiring electrodes 131 and 132 spaced apart in the second direction Y.
  • the plurality of electrode fingers 121 and 122 of the functional electrode 120 each extend along the second direction Y and are positioned along the first direction X with a gap therebetween.
  • electrode finger 121 is connected to wiring electrode 131 and electrode finger 122 is connected to wiring electrode 132 .
  • the functional electrode 120 is configured such that the number of electrode fingers 121 and 122 positioned between the first member 141 and the second member 142 is "10 or more" when viewed along the stacking direction Z.
  • the elastic wave device 1 of FIGS. 13 and 14 includes a functional electrode 120 having ten electrode fingers 121 and 122 located between a first member 141 and a second member 142 .
  • the electrode fingers 121 and 122 when viewed along the stacking direction Z, the electrode fingers 121 and 122 (the center line including the electrode fingers 121 and 122 positioned on L1 and L2) are referred to as "electrode fingers 121 and 122 positioned between the first member 141 and the second member 142".
  • a center line L1 is an imaginary straight line passing through the center of the first member 141 in the first direction X and extending in the second direction Y.
  • a center line L2 is a virtual straight line passing through the center of the second member 142 in the first direction X in the second direction. Suppose it is an imaginary straight line extending in Y.
  • FIG. 16 shows the relationship between return loss and frequency in the elastic wave device 100 shown in FIG.
  • FIG. 17 shows the relationship between the number of electrode fingers 121 and 122 of the functional electrode 120 and the return loss in the portion 200 surrounded by the solid line in FIG. 15 omits components other than the hollow portion 9 of the elastic wave device 100, the membrane portion 21 of the piezoelectric layer 2, the functional electrode 120, and the member 144.
  • FIG. Elastic wave device 100 of FIG. has the same configuration as the elastic wave device 1 .
  • the member 144 is positioned substantially in the center of the cavity 9 in the first direction X. As shown in FIG. “Number of electrode fingers” in FIG.
  • FIG. 17 indicates the number N of electrode fingers 121 and 122 between the member 144 and one end of the cavity 9 in the first direction X (see FIG. 15). As shown in FIG. 17, it can be seen that the return loss improves when the number of electrode fingers 121 and 122 is 10 or more.
  • the elastic wave device 1 includes a supporting substrate 110, a piezoelectric layer 2 provided on the supporting substrate 110, a functional electrode 120 provided on the piezoelectric layer 2, a hollow portion 9, a first member 141 and a second member. 142.
  • the hollow portion 9 is provided inside the support substrate 110 and is positioned so as to partially overlap the functional electrode 120 in plan view along the stacking direction Z of the support substrate 110 and the piezoelectric layer 2 .
  • the first member 141 and the second member 142 are provided in the hollow portion 9 with a gap therebetween in the first direction X, and support the piezoelectric layers 2 in the stacking direction Z, respectively.
  • the functional electrode 120 has a plurality of electrode fingers 121 and 122 spaced apart along the first direction X, and when viewed along the stacking direction Z, between the first member 141 and the second member 142 The number of electrode fingers 121 and 122 positioned at 10 or more. With such a configuration, it is possible to realize the acoustic wave device 1 capable of maintaining a good return loss while preventing deformation of the membrane portion 21 .
  • the elastic wave device 1 of this embodiment can also be configured as follows.
  • the membrane part 21 undergoes a large displacement in the stacking direction Z. Therefore, by setting the number of electrode fingers 121 and 122 between the first member 141 and the second member 142 to 30 or less when viewed along the stacking direction Z, deformation of the membrane portion 21 can be more reliably prevented. .
  • FIG. 18 shows an elastic wave device 1 including a functional electrode 120 having “30” electrode fingers 121 and 122 located between a first member 141 and a second member 142 .
  • each of the first member 141 and the second member 142 has at least one curved corner portion 143 when viewed along the stacking direction Z.
  • all four corners 143 of each of first member 141 and second member 142 are curved. If the corner portion 143 has an acute angle, the stress concentrates on the corner portion 143, and the membrane portion 21 may be destroyed. Since the first member 141 and the second member 142 have the curved corners 143 , the stress of the corners 143 is dispersed and the destruction of the membrane part 21 can be prevented.
  • the electrode fingers 121 and 122 may be arranged so as not to overlap the first member 141 and the second member 142 when viewed along the stacking direction Z. That is, the electrode fingers 121 and 122 may or may not overlap the first member 141 or the second member 142 in the stacking direction Z.
  • the elastic wave device 1 can be manufactured using any method such as a method of forming the cavity 9 using a sacrificial layer or a method of etching the support substrate 110 from the back surface.
  • the support substrate 110 is not limited to being composed only of the support member 8 , and may be configured to include the support member 8 and the insulating layer (bonding layer) 7 provided on the support member 8 . .
  • At least part of the configuration of the elastic wave device 1 of the present disclosure may be added to the elastic wave devices of the first to fourth aspects, or the elastic wave device 1 of the present disclosure may be added to the elastic wave devices of the first to fourth aspects. At least part of the configuration of the acoustic wave device may be added.
  • the elastic wave device of the first aspect is a support substrate; a piezoelectric layer provided on the support substrate; a functional electrode provided on the piezoelectric layer; a hollow portion provided inside the support substrate and overlapping with a part of the functional electrode in a plan view along the stacking direction of the support substrate and the piezoelectric layer; a first member and a second member provided in the cavity in a direction intersecting the stacking direction with a gap therebetween and supporting the piezoelectric layers in the stacking direction;
  • the functional electrode is Having a plurality of electrode fingers spaced apart along a direction intersecting the stacking direction, When viewed along the stacking direction, the number of electrode fingers positioned between the first member and the second member is 10 or more.
  • the elastic wave device of the second aspect is the elastic wave device of the first aspect, When viewed along the stacking direction, the number of electrode fingers positioned between the first member and the second member is 30 or less.
  • a third aspect of the elastic wave device is the elastic wave device of the first aspect or the second aspect, wherein each of the first member and the second member has a curved corner when viewed along the stacking direction. ing.
  • the elastic wave device of the fourth aspect is the elastic wave device of any one of the first to third aspects,
  • the piezoelectric layer includes Z-cut lithium niobate or lithium tantalate.
  • the elastic wave device of the fifth aspect is the elastic wave device of any one of the first to fourth aspects,
  • the functional electrodes are IDT electrodes.
  • the elastic wave device of the sixth aspect is the elastic wave device of the fifth aspect, the piezoelectric layer contains lithium niobate or lithium tantalate, the IDT electrode has a first electrode finger and a second electrode finger facing each other in a direction intersecting the stacking direction; the first electrode finger and the second electrode finger are adjacent electrodes; Where d is the thickness of the piezoelectric layer and p is the center-to-center distance between the first electrode finger and the second electrode finger, d/p is 0.5 or less.
  • the elastic wave device of the seventh aspect is the elastic wave device of the sixth aspect, d/p is 0.24 or less.
  • the eighth-like elastic wave device is the elastic wave device of the sixth aspect or the seventh aspect, the area of the first electrode fingers and the second electrode fingers in the excitation region with respect to the excitation region, which is the region where the first electrode fingers and the second electrode fingers overlap in the direction intersecting the stacking direction;
  • the metallization ratio MR which is a ratio, satisfies MR ⁇ 1.75(d/p)+0.075.
  • the elastic wave device of the ninth aspect is the elastic wave device of any one of the sixth aspect to the eighth aspect,
  • the Euler angles ( ⁇ , ⁇ , ⁇ ) of the lithium niobate or lithium tantalate are within the range of the following formula (1), formula (2) or formula (3).
  • Equation (1) (0° ⁇ 10°, 20° to 80°, 0° to 60° (1-( ⁇ -50) 2 /900) 1/2 ) or (0° ⁇ 10°, 20° to 80°, [180 °-60° (1-( ⁇ -50) 2 /900) 1/2 ] ⁇ 180°) Equation (2) (0° ⁇ 10°, [180°-30°(1-( ⁇ -90) 2 /8100) 1/2 ] ⁇ 180°, arbitrary ⁇ ) Equation (3)
  • the elastic wave device of the tenth aspect is the elastic wave device of any one of the fifth to ninth aspects, the piezoelectric layer contains lithium niobate or lithium tantalate, It is configured to be able to utilize bulk waves in the thickness-shlip mode.
  • the elastic wave device of the eleventh aspect is the elastic wave device of any one of the first to fifth aspects, It is configured to be able to use plate waves.

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Abstract

This elastic wave device comprises: a support substrate; a piezoelectric layer provided on the support substrate; a functional electrode provided on the piezoelectric layer; a cavity portion which is provided inside the support substrate and which is located at a position that partially overlaps with the functional electrode in a plan view when viewed along the lamination direction of the support substrate and the piezoelectric layer; and a first member and a second member which are provided in the cavity portion so as to be spaced apart from each other in a direction intersecting the lamination direction and each of which supports the piezoelectric layer in the lamination direction. The functional electrode has a plurality of electrode fingers positioned so as to be spaced apart from each other along the direction intersecting the lamination direction, and when viewed along the lamination direction, there are at least 10 electrode fingers positioned between the first member and the second member.

Description

弾性波装置Acoustic wave device
　本開示は、圧電層（圧電体層）を備える弾性波装置に関する。 The present disclosure relates to an acoustic wave device including a piezoelectric layer (piezoelectric layer).
　例えば、特許文献１には、板波を利用する弾性波装置が開示されている。特許文献１に記載の弾性波装置は、支持体と、圧電基板と、ＩＤＴ電極とを備えている。支持体には、空洞部が設けられている。圧電基板は、支持体の上に空洞部と重なるように設けられている。ＩＤＴ電極は、圧電基板の上に空洞部と重なるように設けられている。弾性波装置では、ＩＤＴ電極により板波が励振される。空洞部の端縁部は、ＩＤＴ電極により励振される板波の伝搬方向と平行に延びる直線部を含まない。 For example, Patent Document 1 discloses an elastic wave device that uses plate waves. An acoustic wave device described in Patent Document 1 includes a support, a piezoelectric substrate, and an IDT electrode. The support is provided with a cavity. A piezoelectric substrate is provided on the support so as to overlap the cavity. The IDT electrode is provided on the piezoelectric substrate so as to overlap the cavity. In an elastic wave device, plate waves are excited by IDT electrodes. The edge of the cavity does not include a straight portion extending parallel to the propagation direction of the Lamb waves excited by the IDT electrodes.
特開２０１２－２５７０１９号公報JP 2012-257019 A
　近年、メンブレン部を有する弾性波装置において、メンブレン部の変形を防止しつつ、良好なリターンロスを維持可能な弾性波装置が求められている。 In recent years, there has been a demand for an elastic wave device having a membrane that can maintain good return loss while preventing deformation of the membrane.
　本開示は、メンブレン部の変形を防止しつつ、良好なリターンロスを維持可能な弾性波装置を提供することを目的とする。 An object of the present disclosure is to provide an elastic wave device capable of maintaining good return loss while preventing deformation of the membrane portion.
　本開示の一態様の弾性波装置は、
　支持基板と、
　前記支持基板上に設けられた圧電体層と、
　前記圧電体層上に設けられた機能電極と、
　前記支持基板の内部に設けられ、前記支持基板および前記圧電体層の積層方向に沿って見た平面視において前記機能電極の一部と重なる位置にある空洞部と、
　前記空洞部に前記積層方向に交差する方向に間隔を空けてそれぞれ設けられ、前記積層方向において前記圧電体層をそれぞれ支持する第１部材および第２部材と
を備え、
　前記機能電極が、
　前記積層方向に交差する方向に沿って間隔を空けて位置する複数の電極指を有し、
　前記積層方向に沿って見た場合、前記第１部材および前記第２部材の間に位置する前記電極指の数が１０以上である。 An elastic wave device according to one aspect of the present disclosure includes:
a support substrate;
a piezoelectric layer provided on the support substrate;
a functional electrode provided on the piezoelectric layer;
a hollow portion provided inside the support substrate and overlapping with a part of the functional electrode in a plan view along the stacking direction of the support substrate and the piezoelectric layer;
a first member and a second member provided in the cavity in a direction intersecting the stacking direction with a gap therebetween and supporting the piezoelectric layers in the stacking direction;
The functional electrode is
Having a plurality of electrode fingers spaced apart along a direction intersecting the stacking direction,
When viewed along the stacking direction, the number of electrode fingers positioned between the first member and the second member is 10 or more.
　本開示によれば、メンブレン部の変形を防止しつつ、良好なリターンロスを維持可能な弾性波装置を提供できる。 According to the present disclosure, it is possible to provide an elastic wave device capable of maintaining good return loss while preventing deformation of the membrane portion.
第１，第２の態様の弾性波装置の外観を示す略図的斜視図。1 is a schematic perspective view showing the appearance of elastic wave devices of first and second aspects; FIG. 圧電層上の電極構造を示す平面図。FIG. 4 is a plan view showing an electrode structure on the piezoelectric layer; 図１Ａ中のＡ－Ａ線に沿う部分の断面図。Sectional drawing of the part which follows the AA line in FIG. 1A. 従来の弾性波装置の圧電膜を伝搬するラム波を説明するための模式的正面断面図。FIG. 2 is a schematic front cross-sectional view for explaining Lamb waves propagating through a piezoelectric film of a conventional elastic wave device. 本開示の弾性波装置の波を説明するための模式的正面断面図。FIG. 2 is a schematic front cross-sectional view for explaining waves of the elastic wave device of the present disclosure; 第１の電極と第２の電極との間に、第２の電極が第１の電極よりも高電位となる電圧が印加された場合のバルク波を示す模式図。FIG. 4 is a schematic diagram showing a bulk wave when a voltage is applied between the first electrode and the second electrode so that the potential of the second electrode is higher than that of the first electrode. 本開示の一実施形態に係る弾性波装置の共振特性を示す図。FIG. 3 is a diagram showing resonance characteristics of an elastic wave device according to an embodiment of the present disclosure; ｄ／２ｐと、弾性波装置の共振子としての比帯域との関係を示す図。FIG. 4 is a diagram showing the relationship between d/2p and the fractional bandwidth as a resonator of an acoustic wave device; 本開示の一実施形態に係る別の弾性波装置の平面図。The top view of another elastic wave device concerning one embodiment of this indication. 弾性波装置の共振特性の一例を示す参考図。FIG. 2 is a reference diagram showing an example of resonance characteristics of an elastic wave device; 多数の弾性波共振子を構成した場合の比帯域と、スプリアスの大きさとしての１８０度で規格化されたスプリアスのインピーダンスの位相回転量との関係を示す図。FIG. 4 is a diagram showing the relationship between the fractional bandwidth and the amount of phase rotation of the spurious impedance normalized by 180 degrees as the magnitude of the spurious when a large number of acoustic wave resonators are configured; ｄ／２ｐと、メタライゼーション比ＭＲと、比帯域との関係を示す図。4 is a diagram showing the relationship between d/2p, metallization ratio MR, and fractional bandwidth; FIG. ｄ／ｐを限りなく０に近づけた場合のＬｉＮｂＯ３のオイラー角（０°，θ，ψ）に対する比帯域のマップを示す図。FIG. 4 is a diagram showing a map of the fractional bandwidth with respect to the Euler angles (0°, θ, ψ) of LiNbO 3 when d/p is infinitely close to 0; 本開示の一実施形態に係る弾性波装置を説明するための部分切り欠き斜視図。1 is a partially cutaway perspective view for explaining an elastic wave device according to an embodiment of the present disclosure; FIG. 本開示の一実施形態に係る弾性波装置を示す平面図。1 is a plan view showing an elastic wave device according to an embodiment of the present disclosure; FIG. 図１３のXIV-XIV線に沿った断面図。Sectional drawing along the XIV-XIV line of FIG. リターンロスと機能電極の電極指の数との関係を説明するための弾性波装置の部分斜視図。FIG. 4 is a partial perspective view of an elastic wave device for explaining the relationship between return loss and the number of electrode fingers of a functional electrode; リターンロスと周波数との関係を示すグラフ。Graph showing the relationship between return loss and frequency. リターンロスと機能電極の電極指の数との関係を示すグラフ。4 is a graph showing the relationship between return loss and the number of electrode fingers of a functional electrode; 図１３の弾性波装置の第１の変形例を示す平面図。The top view which shows the 1st modification of the elastic wave apparatus of FIG. 図１３の弾性波装置の第２の変形例を示す平面図。The top view which shows the 2nd modification of the elastic wave apparatus of FIG.
　以下、本開示の一例を添付図面に従って説明する。以下の説明は、本質的に例示に過ぎず、本開示、本開示の適用物、または、本開示の用途を制限することを意図するものではない。図面は模式的なものであり、各寸法の比率等は現実のものとは必ずしも合致していない。 An example of the present disclosure will be described below with reference to the accompanying drawings. The following description is merely exemplary in nature and is not intended to limit the disclosure, the application of the disclosure, or the uses of the disclosure. The drawings are schematic, and the ratio of each dimension does not necessarily match the actual one.
　図１Ａ～図１２を参照して、本開示の基礎となる第１～第４の態様の弾性波装置について説明する。 1A to 12, the elastic wave devices of the first to fourth aspects that form the basis of the present disclosure will be described.
　本開示における第１，第２，第３の態様の弾性波装置は、例えば、ニオブ酸リチウムまたはタンタル酸リチウムからなる圧電層と、圧電層の厚み方向に交差する方向において対向する第１電極及び第２電極とを備える。 Elastic wave devices according to the first, second, and third aspects of the present disclosure include, for example, a piezoelectric layer made of lithium niobate or lithium tantalate, first electrodes facing each other in a direction intersecting the thickness direction of the piezoelectric layer, and and a second electrode.
　第１の態様の弾性波装置では、厚み滑り１次モードのバルク波が利用されている。 In the elastic wave device of the first aspect, bulk waves in the primary mode of thickness shear are used.
　また、第２の態様の弾性波装置では、第１電極及び前記第２電極は隣り合う電極同士であり、圧電層の厚みをｄ、第１電極及び第２電極の中心間距離をｐとした場合、ｄ／ｐが０．５以下とされている。それによって、第１，第２の態様では、小型化を進めた場合であっても、Ｑ値を高めることができる。 Further, in the acoustic wave device of the second aspect, the first electrode and the second electrode are adjacent electrodes, the thickness of the piezoelectric layer is d, and the distance between the centers of the first electrode and the second electrode is p. In this case, d/p is 0.5 or less. As a result, in the first and second aspects, the Q value can be increased even when the miniaturization is promoted.
　また、第３の態様の弾性波装置では、板波としてのラム波が利用される。そして、上記ラム波による共振特性を得ることができる。 Also, in the elastic wave device of the third aspect, Lamb waves are used as plate waves. Then, resonance characteristics due to the Lamb wave can be obtained.
　本開示における第４の態様の弾性波装置は、ニオブ酸リチウムまたはタンタル酸リチウムからなる圧電層と、圧電層を挟んで圧電層の厚み方向に対向する上部電極及び下部電極とを備え、バルク波を利用する。 An acoustic wave device according to a fourth aspect of the present disclosure includes a piezoelectric layer made of lithium niobate or lithium tantalate, and an upper electrode and a lower electrode facing each other in the thickness direction of the piezoelectric layer with the piezoelectric layer interposed therebetween. take advantage of
　以下、図面を参照しつつ、第１～第４の態様の弾性波装置の具体的な実施形態を説明することにより、本開示を明らかにする。 Hereinafter, the present disclosure will be clarified by describing specific embodiments of the elastic wave devices of the first to fourth aspects with reference to the drawings.
　なお、本明細書に記載の各実施形態は、例示的なものであり、異なる実施形態間において、構成の部分的な置換または組み合わせが可能であることを指摘しておく。 It should be noted that each embodiment described in this specification is exemplary, and partial replacement or combination of configurations is possible between different embodiments.
　図１Ａは、第１，第２の態様についての一実施形態に係る弾性波装置の外観を示す略図的斜視図であり、図１Ｂは、圧電層上の電極構造を示す平面図であり、図２は、図１Ａ中のＡ－Ａ線に沿う部分の断面図である。 FIG. 1A is a schematic perspective view showing the appearance of an acoustic wave device according to one embodiment of the first and second aspects, and FIG. 1B is a plan view showing an electrode structure on a piezoelectric layer. 2 is a cross-sectional view of a portion taken along line AA in FIG. 1A.
　弾性波装置１は、ＬｉＮｂＯ3からなる圧電層２を有する。圧電層２は、ＬｉＴａＯ3からなるものであってもよい。ＬｉＮｂＯ3やＬｉＴａＯ3のカット角は、本実施形態では、Ｚカットであるが、回転ＹカットやＸカットであってもよい。好ましくは、Ｙ伝搬及びＸ伝搬±３０°の伝搬方位が好ましい。圧電層２の厚みは、特に限定されないが、厚み滑り１次モードを効果的に励振するには、５０ｎｍ以上、１０００ｎｍ以下が好ましい。 The acoustic wave device 1 has a piezoelectric layer 2 made of LiNbO 3 . The piezoelectric layer 2 may consist of LiTaO 3 . The cut angle of LiNbO 3 and LiTaO 3 is Z-cut in this embodiment, but may be rotational Y-cut or X-cut. Preferably, the Y-propagation and X-propagation ±30° propagation orientations are preferred. Although the thickness of the piezoelectric layer 2 is not particularly limited, it is preferably 50 nm or more and 1000 nm or less in order to effectively excite the thickness-shear primary mode.
　圧電層２は、対向し合う第１，第２の主面２ａ，２ｂを有する。第１の主面２ａ上に、電極３及び電極４が設けられている。ここで電極３が「第１電極」の一例であり、電極４が「第２電極」の一例である。図１Ａ及び図１Ｂでは、複数の電極３が、第１のバスバー５に接続されている複数の第１の電極指である。複数の電極４は、第２のバスバー６に接続されている複数の第２の電極指である。複数の電極３及び複数の電極４は、互いに間挿し合っている。 The piezoelectric layer 2 has first and second main surfaces 2a and 2b facing each other. Electrodes 3 and 4 are provided on the first main surface 2a. Here, the electrode 3 is an example of the "first electrode" and the electrode 4 is an example of the "second electrode". In FIGS. 1A and 1B, the multiple electrodes 3 are multiple first electrode fingers connected to a first busbar 5 . The multiple electrodes 4 are multiple second electrode fingers connected to the second bus bar 6 . The plurality of electrodes 3 and the plurality of electrodes 4 are interleaved with each other.
　電極３及び電極４は、矩形形状を有し、長さ方向を有する。この長さ方向と直交する方向において、電極３と、隣りの電極４とが対向している。これら複数の電極３，４、及び第１のバスバー５，第２のバスバー６によりＩＤＴ（Ｉｎｔｅｒｄｉｇｉｔａｌ　Ｔｒａｎｓｕｄｕｃｅｒ）電極が構成されている。電極３，４の長さ方向、及び、電極３，４の長さ方向と直交する方向はいずれも、圧電層２の厚み方向に交差する方向である。このため、電極３と、隣りの電極４とは、圧電層２の厚み方向に交差する方向において対向しているともいえる。 The electrodes 3 and 4 have a rectangular shape and a length direction. The electrode 3 and the adjacent electrode 4 face each other in a direction perpendicular to the length direction. These electrodes 3 and 4, the first bus bar 5 and the second bus bar 6 constitute an IDT (Interdigital Transducer) electrode. Both the length direction of the electrodes 3 and 4 and the direction orthogonal to the length direction of the electrodes 3 and 4 are directions crossing the thickness direction of the piezoelectric layer 2 . Therefore, it can be said that the electrode 3 and the adjacent electrode 4 face each other in the direction intersecting the thickness direction of the piezoelectric layer 2 .
　また、電極３，４の長さ方向が図１Ａ及び図１Ｂに示す電極３，４の長さ方向に直交する方向と入れ替わってもよい。すなわち、図１Ａ及び図１Ｂにおいて、第１のバスバー５及び第２のバスバー６が延びている方向に電極３，４を延ばしてもよい。その場合、第１のバスバー５及び第２のバスバー６は、図１Ａ及び図１Ｂにおいて電極３，４が延びている方向に延びることとなる。 Also, the length direction of the electrodes 3 and 4 may be interchanged with the direction orthogonal to the length direction of the electrodes 3 and 4 shown in FIGS. 1A and 1B. That is, in FIGS. 1A and 1B, the electrodes 3 and 4 may extend in the direction in which the first busbar 5 and the second busbar 6 extend. In that case, the first busbar 5 and the second busbar 6 extend in the direction in which the electrodes 3 and 4 extend in FIGS. 1A and 1B.
　そして、一方電位に接続される電極３と、他方電位に接続される電極４とが隣り合う１対の構造が、上記電極３，４の長さ方向と直交する方向に、複数対設けられている。ここで電極３と電極４とが隣り合うとは、電極３と電極４とが直接接触するように配置されている場合ではなく、電極３と電極４とが間隔を介して配置されている場合を指す。 A plurality of pairs of structures in which an electrode 3 connected to one potential and an electrode 4 connected to the other potential are adjacent to each other are provided in a direction perpendicular to the length direction of the electrodes 3 and 4. there is Here, when the electrodes 3 and 4 are adjacent to each other, it does not mean that the electrodes 3 and 4 are arranged so as to be in direct contact with each other, but that the electrodes 3 and 4 are arranged with a gap therebetween. point to
　また、電極３と電極４とが隣り合う場合、電極３と電極４との間には、他の電極３，４を含む、ホット電極やグランド電極に接続される電極は配置されない。この対数は、整数対である必要はなく、１．５対や２．５対などであってもよい。電極３，４間の中心間距離すなわちピッチは、１μｍ以上、１０μｍ以下の範囲が好ましい。また、電極３，４間の中心間距離とは、電極３の長さ方向と直交する方向における電極３の幅寸法の中心と、電極４の長さ方向と直交する方向における電極４の幅寸法の中心とを結んだ距離となる。さらに、電極３，４の少なくとも一方が複数本ある場合（電極３，４を一対の電極組とし、１．５対以上の電極組がある場合）、電極３，４の中心間距離は、１．５対以上の電極３，４のうち隣り合う電極３，４それぞれの中心間距離の平均値を指す。また、電極３，４の幅、すなわち電極３，４の対向方向の寸法は、１５０ｎｍ以上、１０００ｎｍ以下の範囲が好ましい。なお、電極３，４間の中心間距離とは、電極３の長さ方向と直交する方向における電極３の寸法（幅寸法）の中心と、電極４の長さ方向と直交する方向における電極４の寸法（幅寸法）の中心とを結んだ距離となる。 Also, when the electrode 3 and the electrode 4 are adjacent to each other, no electrode connected to the hot electrode or the ground electrode, including the other electrodes 3 and 4, is arranged between the electrode 3 and the electrode 4. The logarithms need not be integer pairs, but may be 1.5 pairs, 2.5 pairs, or the like. The center-to-center distance or pitch between the electrodes 3 and 4 is preferably in the range of 1 μm or more and 10 μm or less. Further, the center-to-center distance between the electrodes 3 and 4 means the center of the width dimension of the electrode 3 in the direction perpendicular to the length direction of the electrode 3 and the width dimension of the electrode 4 in the direction perpendicular to the length direction of the electrode 4. is the distance connecting the center of Furthermore, when at least one of the electrodes 3 and 4 has a plurality of electrodes (when the electrodes 3 and 4 are a pair of electrodes and there are 1.5 or more pairs of electrodes), the center-to-center distance between the electrodes 3 and 4 is 1. .The average distance between the centers of adjacent electrodes 3 and 4 out of 5 or more pairs of electrodes 3 and 4. Moreover, the width of the electrodes 3 and 4, that is, the dimension in the facing direction of the electrodes 3 and 4 is preferably in the range of 150 nm or more and 1000 nm or less. Note that the center-to-center distance between the electrodes 3 and 4 means the distance between the center of the dimension (width dimension) of the electrode 3 in the direction orthogonal to the length direction of the electrode 3 and the distance between the center of the electrode 4 in the direction orthogonal to the length direction of the electrode 4. It is the distance connecting the center of the dimension (width dimension) of
　また、本実施形態では、Ｚカットの圧電層を用いているため、電極３，４の長さ方向と直交する方向は、圧電層２の分極方向に直交する方向となる。圧電層２として他のカット角の圧電体を用いた場合には、この限りでない。ここにおいて、「直交」とは、厳密に直交する場合のみに限定されず、略直交（電極３，４の長さ方向と直交する方向と分極方向とのなす角度が例えば９０°±１０°）でもよい。 In addition, since the Z-cut piezoelectric layer is used in this embodiment, the direction perpendicular to the length direction of the electrodes 3 and 4 is the direction perpendicular to the polarization direction of the piezoelectric layer 2 . This is not the case when a piezoelectric material with a different cut angle is used as the piezoelectric layer 2 . Here, "perpendicular" is not limited to being strictly perpendicular, but substantially perpendicular (the angle formed by the direction perpendicular to the length direction of the electrodes 3 and 4 and the polarization direction is, for example, 90°±10°). It's okay.
　圧電層２の第２の主面２ｂ側には、絶縁層７を介して支持部材８が積層されている。絶縁層７及び支持部材８は、枠状の形状を有し、図２に示すように、開口部７ａ，８ａを有する。それによって、空洞部９が形成されている。空洞部９は、圧電層２の励振領域Ｃの振動を妨げないために設けられている。従って、上記支持部材８は、少なくとも１対の電極３，４が設けられている部分と重ならない位置において、第２の主面２ｂに絶縁層７を介して積層されている。なお、絶縁層７は設けられずともよい。従って、支持部材８は、圧電層２の第２の主面２ｂに直接または間接に積層され得る。 A supporting member 8 is laminated on the second main surface 2b side of the piezoelectric layer 2 with an insulating layer 7 interposed therebetween. The insulating layer 7 and the support member 8 have a frame shape and, as shown in FIG. 2, have openings 7a and 8a. A cavity 9 is thereby formed. The cavity 9 is provided so as not to disturb the vibration of the excitation region C of the piezoelectric layer 2 . Therefore, the support member 8 is laminated on the second main surface 2b with the insulating layer 7 interposed therebetween at a position not overlapping the portion where at least one pair of electrodes 3 and 4 are provided. Note that the insulating layer 7 may not be provided. Therefore, the support member 8 can be directly or indirectly laminated to the second main surface 2b of the piezoelectric layer 2 .
　絶縁層７は、酸化ケイ素からなる。もっとも、酸化ケイ素の他、酸窒化ケイ素、アルミナなどの適宜の絶縁性材料を用いることができる。支持部材８は、Ｓｉからなる。Ｓｉの圧電層２側の面における面方位は（１００）や（１１０）であってもよく、（１１１）であってもよい。好ましくは、抵抗率４ｋΩ以上の高抵抗のＳｉが望ましい。もっとも、支持部材８についても適宜の絶縁性材料や半導体材料を用いて構成することができる。支持部材８の材料としては、例えば、酸化アルミニウム、タンタル酸リチウム、ニオブ酸リチウム、水晶などの圧電体、アルミナ、マグネシア、サファイア、窒化ケイ素、窒化アルミニウム、炭化ケイ素、ジルコニア、コージライト、ムライト、ステアタイト、フォルステライトなどの各種セラミック、ダイヤモンド、ガラスなどの誘電体、窒化ガリウムなどの半導体などを用いることができる。 The insulating layer 7 is made of silicon oxide. However, in addition to silicon oxide, suitable insulating materials such as silicon oxynitride and alumina can be used. The support member 8 is made of Si. The plane orientation of the surface of Si on the piezoelectric layer 2 side may be (100), (110), or (111). Preferably, high-resistance Si having a resistivity of 4 kΩ or more is desirable. However, the supporting member 8 can also be constructed using an appropriate insulating material or semiconductor material. Materials for the support member 8 include, for example, aluminum oxide, lithium tantalate, lithium niobate, piezoelectric materials such as crystal, alumina, magnesia, sapphire, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mullite, and steer. Various ceramics such as tight and forsterite, dielectrics such as diamond and glass, and semiconductors such as gallium nitride can be used.
　上記複数の電極３，４及び第１，第２のバスバー５，６は、Ａｌ、ＡｌＣｕ合金などの適宜の金属もしくは合金からなる。本実施形態では、電極３，４及び第１，第２のバスバー５，６は、Ｔｉ膜上にＡｌ膜を積層した構造を有する。なお、Ｔｉ膜以外の密着層を用いてもよい。 The plurality of electrodes 3, 4 and the first and second bus bars 5, 6 are made of appropriate metals or alloys such as Al, AlCu alloys. In this embodiment, the electrodes 3 and 4 and the first and second bus bars 5 and 6 have a structure in which an Al film is laminated on a Ti film. Note that an adhesion layer other than the Ti film may be used.
　駆動に際しては、複数の電極３と、複数の電極４との間に交流電圧を印加する。より具体的には、第１のバスバー５と第２のバスバー６との間に交流電圧を印加する。それによって、圧電層２において励振される厚み滑り１次モードのバルク波を利用した、共振特性を得ることが可能とされている。 When driving, an AC voltage is applied between the multiple electrodes 3 and the multiple electrodes 4 . More specifically, an AC voltage is applied between the first busbar 5 and the second busbar 6 . As a result, it is possible to obtain resonance characteristics using a thickness-shear primary mode bulk wave excited in the piezoelectric layer 2 .
　また、弾性波装置１では、圧電層２の厚みをｄ、複数対の電極３，４のうちいずれかの隣り合う電極３，４の中心間距離をｐとした場合、ｄ／ｐは０．５以下とされている。そのため、上記厚み滑り１次モードのバルク波が効果的に励振され、良好な共振特性を得ることができる。より好ましくは、ｄ／ｐは０．２４以下であり、その場合には、より一層良好な共振特性を得ることができる。 Further, in the acoustic wave device 1, d/p is 0.0, where d is the thickness of the piezoelectric layer 2 and p is the center-to-center distance between any one of the pairs of electrodes 3 and 4 adjacent to each other. 5 or less. As a result, the thickness-shear primary mode bulk wave is effectively excited, and good resonance characteristics can be obtained. More preferably, d/p is 0.24 or less, in which case even better resonance characteristics can be obtained.
　なお、本実施形態のように電極３，４の少なくとも一方が複数本ある場合、すなわち、電極３，４を１対の電極組とし、電極３，４が１．５対以上ある場合、隣り合う電極３，４の中心間距離ｐは、各隣り合う電極３，４の中心間距離の平均距離となる。 Note that when at least one of the electrodes 3 and 4 is plural as in this embodiment, that is, when the electrodes 3 and 4 form one pair of electrodes and there are 1.5 or more pairs of electrodes 3 and 4, adjacent The center-to-center distance p of the electrodes 3 and 4 is the average distance between the center-to-center distances of each adjacent electrode 3 and 4 .
　本実施形態の弾性波装置１では、上記構成を備えるため、小型化を図ろうとして、電極３，４の対数を小さくしたとしても、Ｑ値の低下が生じ難い。これは、両側に反射器を必要としない共振器であり、伝搬ロスが少ないためである。また、上記反射器を必要としないのは、厚み滑り１次モードのバルク波を利用していることによる。 Since the elastic wave device 1 of the present embodiment has the above configuration, even if the logarithm of the electrodes 3 and 4 is reduced in order to reduce the size, the Q value is unlikely to decrease. This is because the resonator does not require reflectors on both sides, and the propagation loss is small. The reason why the above reflector is not required is that the bulk wave of the thickness-shlip primary mode is used.
　従来の弾性波装置で利用したラム波と、上記厚み滑り１次モードのバルク波の相違を、図３Ａ及び図３Ｂを参照して説明する。 The difference between the Lamb wave used in the conventional elastic wave device and the bulk wave of the thickness shear primary mode will be described with reference to FIGS. 3A and 3B.
　図３Ａは、従来の弾性波装置の圧電膜を伝搬するラム波を説明するための模式的正面断面図である。従来の弾性波装置については、例えば、特許文献１（特開２０１２－２５７０１９号公報）に記載されている。図３Ａに示すように、従来の弾性波装置においては、圧電膜２０１中を矢印で示すように波が伝搬する。ここで、圧電膜２０１では、第１の主面２０１ａと、第２の主面２０１ｂとが対向しており、第１の主面２０１ａと第２の主面２０１ｂとを結ぶ厚み方向がＺ方向である。Ｘ方向は、ＩＤＴ電極の電極指が並んでいる方向である。図３Ａに示すように、ラム波では、波が図示のように、Ｘ方向に伝搬していく。板波であるため、圧電膜２０１が全体として振動するものの、波はＸ方向に伝搬するため、両側に反射器を配置して、共振特性を得ている。そのため、波の伝搬ロスが生じ、小型化を図った場合、すなわち電極指の対数を少なくした場合、Ｑ値が低下する。 FIG. 3A is a schematic front cross-sectional view for explaining Lamb waves propagating through a piezoelectric film of a conventional elastic wave device. A conventional elastic wave device is described, for example, in Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2012-257019). As shown in FIG. 3A, in the conventional acoustic wave device, waves propagate through the piezoelectric film 201 as indicated by arrows. Here, in the piezoelectric film 201, the first main surface 201a and the second main surface 201b face each other, and the thickness direction connecting the first main surface 201a and the second main surface 201b is the Z direction. is. The X direction is the direction in which the electrode fingers of the IDT electrodes are arranged. As shown in FIG. 3A, in the Lamb wave, the wave propagates in the X direction as shown. Since it is a plate wave, although the piezoelectric film 201 as a whole vibrates, since the wave propagates in the X direction, reflectors are arranged on both sides to obtain resonance characteristics. Therefore, a wave propagation loss occurs, and the Q value decreases when miniaturization is attempted, that is, when the logarithm of the electrode fingers is decreased.
　これに対して、図３Ｂに示すように、本実施形態の弾性波装置１では、振動変位は厚み滑り方向であるから、波は、圧電層２の第１の主面２ａと第２の主面２ｂとを結ぶ方向、すなわちＺ方向にほぼ伝搬し、共振する。すなわち、波のＸ方向成分がＺ方向成分に比べて著しく小さい。そして、このＺ方向の波の伝搬により共振特性が得られるため、反射器を必要としない。よって、反射器に伝搬する際の伝搬損失は生じない。従って、小型化を進めようとして、電極３，４からなる電極対の対数を減らしたとしても、Ｑ値の低下が生じ難い。 On the other hand, as shown in FIG. 3B, in the acoustic wave device 1 of the present embodiment, since the vibration displacement is in the thickness sliding direction, the wave is generated between the first main surface 2a and the second main surface 2a of the piezoelectric layer 2. It propagates almost in the direction connecting the surface 2b, that is, in the Z direction, and resonates. That is, the X-direction component of the wave is significantly smaller than the Z-direction component. Further, since resonance characteristics are obtained by propagating waves in the Z direction, no reflector is required. Therefore, no propagation loss occurs when propagating to the reflector. Therefore, even if the number of electrode pairs consisting of the electrodes 3 and 4 is reduced in an attempt to promote miniaturization, the Q value is unlikely to decrease.
　なお、厚み滑り１次モードのバルク波の振幅方向は、図４に示すように、圧電層２の励振領域Ｃに含まれる第１領域４５１と、励振領域Ｃに含まれる第２領域４５２とで逆になる。図４は、電極３と電極４との間に、電極４が電極３よりも高電位となる電圧が印加された場合のバルク波を模式的に示している。第１領域４５１は、励振領域Ｃのうち、圧電層２の厚み方向に直交し圧電層２を２分する仮想平面ＶＰ１と、第１の主面２ａとの間の領域である。第２領域４５２は、励振領域Ｃのうち、仮想平面ＶＰ１と、第２の主面２ｂとの間の領域である。 As shown in FIG. 4, the amplitude direction of the bulk wave of the primary thickness-shear mode is defined by the first region 451 included in the excitation region C of the piezoelectric layer 2 and the second region 452 included in the excitation region C. Reverse. FIG. 4 schematically shows bulk waves when a voltage is applied between the electrodes 3 and 4 so that the potential of the electrode 4 is higher than that of the electrode 3 . The first region 451 is a region of the excitation region C between the first main surface 2a and a virtual plane VP1 that is perpendicular to the thickness direction of the piezoelectric layer 2 and bisects the piezoelectric layer 2 . The second region 452 is a region of the excitation region C between the virtual plane VP1 and the second main surface 2b.
　上記のように、弾性波装置１では、電極３と電極４とからなる少なくとも１対の電極が配置されているが、Ｘ方向に波を伝搬させるものではないため、この電極３，４からなる電極対の対数は複数対ある必要は必ずしもない。すなわち、少なくとも１対の電極が設けられてさえおればよい。 As described above, in the acoustic wave device 1, at least one pair of electrodes consisting of the electrodes 3 and 4 is arranged. It is not always necessary to have a plurality of pairs of electrode pairs. That is, it is sufficient that at least one pair of electrodes is provided.
　例えば、上記電極３がホット電位に接続される電極であり、電極４がグラウンド電位に接続される電極である。もっとも、電極３がグラウンド電位に、電極４がホット電位に接続されてもよい。本実施形態では、少なくとも１対の電極は、上記のように、ホット電位に接続される電極またはグラウンド電位に接続される電極であり、浮き電極は設けられていない。 For example, the electrode 3 is an electrode connected to a hot potential, and the electrode 4 is an electrode connected to a ground potential. However, electrode 3 may also be connected to ground potential and electrode 4 to hot potential. In this embodiment, at least one pair of electrodes is an electrode connected to a hot potential or an electrode connected to a ground potential, as described above, and no floating electrodes are provided.
　図５は、本開示の一実施形態の弾性波装置の共振特性を示す図である。なお、この共振特性を得た弾性波装置１の設計パラメータは以下の通りである。
　圧電層２：オイラー角（０°，０°，９０°）のＬｉＮｂＯ3、厚み＝４００ｎｍ。
　電極３と電極４の長さ方向と直交する方向に視たときに、電極３と電極４とが重なっている領域、すなわち励振領域Ｃの長さ＝４０μｍ、電極３，４からなる電極の対数＝２１対、電極間中心距離＝３μｍ、電極３，４の幅＝５００ｎｍ、ｄ／ｐ＝０．１３３。
　絶縁層７：１μｍの厚みの酸化ケイ素膜。
　支持部材８：Ｓｉ。 FIG. 5 is a diagram showing resonance characteristics of an acoustic wave device according to an embodiment of the present disclosure; The design parameters of the elastic wave device 1 with this resonance characteristic are as follows.
Piezoelectric layer 2: LiNbO 3 with Euler angles (0°, 0°, 90°), thickness = 400 nm.
When viewed in the direction orthogonal to the length direction of the electrodes 3 and 4, the length of the region where the electrodes 3 and 4 overlap, that is, the length of the excitation region C = 40 μm, the number of pairs of electrodes 3 and 4 = 21 pairs, center distance between electrodes = 3 µm, width of electrodes 3 and 4 = 500 nm, d/p = 0.133.
Insulating layer 7: Silicon oxide film with a thickness of 1 μm.
Support member 8: Si.
　なお、励振領域Ｃの長さとは、励振領域Ｃの電極３，４の長さ方向に沿う寸法である。 The length of the excitation region C is the dimension along the length direction of the electrodes 3 and 4 of the excitation region C.
　本実施形態では、電極３，４からなる電極対の電極間距離は、複数対において全て等しくした。すなわち、電極３と電極４とを等ピッチで配置した。 In this embodiment, the inter-electrode distances of the electrode pairs consisting of the electrodes 3 and 4 are all the same in a plurality of pairs. That is, the electrodes 3 and 4 were arranged at equal pitches.
　図５から明らかなように、反射器を有しないにもかかわらず、比帯域が１２．５％である良好な共振特性が得られている。 As is clear from FIG. 5, good resonance characteristics with a specific bandwidth of 12.5% are obtained in spite of having no reflector.
　ところで、上記圧電層２の厚みをｄ、電極３と電極４との電極の中心間距離をｐとした場合、前述したように、本実施形態では、ｄ／ｐは０．５以下、より好ましくは０．２４以下である。これを、図６を参照して説明する。 By the way, when the thickness of the piezoelectric layer 2 is d, and the center-to-center distance between the electrodes 3 and 4 is p, in the present embodiment, d/p is more preferably 0.5 or less, as described above. is less than or equal to 0.24. This will be explained with reference to FIG.
　図５に示した共振特性を得た弾性波装置と同様に、但しｄ／２ｐを変化させ、複数の弾性波装置を得た。図６は、このｄ／２ｐと、弾性波装置の共振子としての比帯域との関係を示す図である。 A plurality of elastic wave devices were obtained by changing d/2p in the same manner as the elastic wave device that obtained the resonance characteristics shown in FIG. FIG. 6 is a diagram showing the relationship between this d/2p and the fractional bandwidth of the acoustic wave device as a resonator.
　図６から明らかなように、ｄ／２ｐが０．２５を超えると、すなわちｄ／ｐ＞０．５では、ｄ／ｐを調整しても、比帯域は５％未満である。これに対して、ｄ／２ｐ≦０．２５、すなわちｄ／ｐ≦０．５の場合には、その範囲内でｄ／ｐを変化させれば、比帯域を５％以上とすることができ、すなわち高い結合係数を有する共振子を構成することができる。また、ｄ／２ｐが０．１２以下の場合、すなわちｄ／ｐが０．２４以下の場合には、比帯域を７％以上と高めることができる。加えて、ｄ／ｐをこの範囲内で調整すれば、より一層比帯域の広い共振子を得ることができ、より一層高い結合係数を有する共振子を実現することができる。従って、本開示の第２の態様の弾性波装置のように、ｄ／ｐを０．５以下とすることにより、上記厚み滑り１次モードのバルク波を利用した、高い結合係数を有する共振子を構成し得ることがわかる。 As is clear from FIG. 6, when d/2p exceeds 0.25, that is, when d/p>0.5, even if d/p is adjusted, the fractional bandwidth is less than 5%. On the other hand, when d/2p≦0.25, that is, when d/p≦0.5, the specific bandwidth can be increased to 5% or more by changing d/p within that range. , that is, a resonator having a high coupling coefficient can be constructed. Further, when d/2p is 0.12 or less, that is, when d/p is 0.24 or less, the specific bandwidth can be increased to 7% or more. In addition, by adjusting d/p within this range, a resonator with a wider specific band can be obtained, and a resonator with a higher coupling coefficient can be realized. Therefore, like the elastic wave device of the second aspect of the present disclosure, by setting d/p to 0.5 or less, a resonator having a high coupling coefficient that utilizes the bulk wave of the primary thickness shear mode can be constructed.
　なお、前述したように、少なくとも１対の電極は、１対でもよく、上記ｐは、１対の電極の場合、隣り合う電極３，４の中心間距離とする。また、１．５対以上の電極の場合には、隣り合う電極３，４の中心間距離の平均距離をｐとすればよい。 As described above, at least one pair of electrodes may be one pair, and p is the center-to-center distance between adjacent electrodes 3 and 4 in the case of one pair of electrodes. In the case of 1.5 pairs or more of electrodes, the average distance between the centers of adjacent electrodes 3 and 4 should be p.
　また、圧電層の厚みｄについても、圧電層２が厚みばらつきを有する場合、その厚みを平均化した値を採用すればよい。 Also, for the thickness d of the piezoelectric layer, if the piezoelectric layer 2 has variations in thickness, a value obtained by averaging the thickness may be adopted.
　図７は、本開示の一実施形態に係る別の弾性波装置の平面図である。弾性波装置３１では、圧電層２の第１の主面２ａ上において、電極３と電極４とを有する１対の電極が設けられている。なお、図７中のＫが交差幅となる。前述したように、本開示の弾性波装置３１では、電極の対数は１対であってもよい。この場合においても、上記ｄ／ｐが０．５以下であれば、厚み滑り１次モードのバルク波を効果的に励振することができる。 FIG. 7 is a plan view of another elastic wave device according to one embodiment of the present disclosure. In elastic wave device 31 , a pair of electrodes having electrode 3 and electrode 4 is provided on first main surface 2 a of piezoelectric layer 2 . Note that K in FIG. 7 is the intersection width. As described above, in the elastic wave device 31 of the present disclosure, the number of pairs of electrodes may be one. Even in this case, if the above d/p is 0.5 or less, it is possible to effectively excite the bulk wave in the primary mode of thickness shear.
　弾性波装置１では、好ましくは、複数の電極３，４において、いずれかの隣り合う電極３，４が対向している方向に視たときに重なっている領域である励振領域に対する、上記隣り合う電極３，４のメタライゼーション比ＭＲが、ＭＲ≦１．７５（ｄ／ｐ）＋０．０７５を満たすことが望ましい。つまり、隣り合う複数の第１電極指と複数の第２電極指とが対向している方向に視たときに複数の第１電極指と複数の第２電極指とが重なっている領域が励振領域（交叉領域）であり、励振領域に対する、複数の第１電極指及び複数の第２電極指のメタライゼーション比をＭＲとしたときに、ＭＲ≦１．７５（ｄ／ｐ）＋０．０７５を満たすことが好ましい。その場合には、スプリアスを効果的に小さくすることができる。 In the elastic wave device 1, preferably, in the plurality of electrodes 3 and 4, the adjacent electrodes 3 and 4 with respect to the excitation region, which is an overlapping region when viewed in the direction in which any of the adjacent electrodes 3 and 4 face each other. It is desirable that the metallization ratio MR of the electrodes 3 and 4 satisfy MR≦1.75(d/p)+0.075. That is, when viewed in the direction in which the plurality of adjacent first electrode fingers and the plurality of second electrode fingers face each other, the region where the plurality of first electrode fingers and the plurality of second electrode fingers overlap is excited. region (intersecting region), where MR is the metallization ratio of the plurality of first electrode fingers and the plurality of second electrode fingers to the excitation region, MR≤1.75(d/p)+0.075. preferably fulfilled. In that case, spurious can be effectively reduced.
　これを、図８及び図９を参照して説明する。図８は、上記弾性波装置１の共振特性の一例を示す参考図である。矢印Ｂで示すスプリアスが、共振周波数と反共振周波数との間に現れている。なお、ｄ／ｐ＝０．０８として、かつＬｉＮｂＯ3のオイラー角（０°，０°，９０°）とした。また、上記メタライゼーション比ＭＲ＝０．３５とした。 This will be described with reference to FIGS. 8 and 9. FIG. FIG. 8 is a reference diagram showing an example of resonance characteristics of the acoustic wave device 1. As shown in FIG. A spurious signal indicated by an arrow B appears between the resonance frequency and the anti-resonance frequency. Note that d/p=0.08 and the Euler angles of LiNbO 3 (0°, 0°, 90°). Also, the metallization ratio MR was set to 0.35.
　メタライゼーション比ＭＲを、図１Ｂを参照して説明する。図１Ｂの電極構造において、１対の電極３，４に着目した場合、この１対の電極３，４のみが設けられるとする。この場合、一点鎖線Ｃで囲まれた部分が励振領域となる。この励振領域とは、電極３と電極４とを、電極３，４の長さ方向と直交する方向すなわち対向方向に視たときに電極３における電極４と重なり合っている領域、電極４における電極３と重なり合っている領域、及び、電極３と電極４との間の領域における電極３と電極４とが重なり合っている領域である。そして、この励振領域の面積に対する、励振領域Ｃ内の電極３，４の面積が、メタライゼーション比ＭＲとなる。すなわち、メタライゼーション比ＭＲは、メタライゼーション部分の面積の励振領域の面積に対する比である。 The metallization ratio MR will be explained with reference to FIG. 1B. In the electrode structure of FIG. 1B, when focusing on the pair of electrodes 3 and 4, it is assumed that only the pair of electrodes 3 and 4 are provided. In this case, the portion surrounded by the dashed-dotted line C is the excitation region. The excitation region means a region where the electrode 3 and the electrode 4 overlap each other when the electrodes 3 and 4 are viewed in a direction orthogonal to the length direction of the electrodes 3 and 4, that is, in a facing direction. and a region where the electrodes 3 and 4 in the region between the electrodes 3 and 4 overlap. The area of the electrodes 3 and 4 in the excitation region C with respect to the area of this excitation region is the metallization ratio MR. That is, the metallization ratio MR is the ratio of the area of the metallization portion to the area of the drive region.
　なお、複数対の電極が設けられている場合、励振領域の面積の合計に対する全励振領域に含まれているメタライゼーション部分の割合をＭＲとすればよい。 When a plurality of pairs of electrodes are provided, MR may be the ratio of the metallization portion included in the entire excitation region to the total area of the excitation region.
　図９は本実施形態に従って、多数の弾性波共振子を構成した場合の比帯域と、スプリアスの大きさとしての１８０度で規格化されたスプリアスのインピーダンスの位相回転量との関係を示す図である。なお、比帯域については、圧電層の膜厚や電極の寸法を種々変更し、調整した。また、図９は、ＺカットのＬｉＮｂＯ3からなる圧電層を用いた場合の結果であるが、他のカット角の圧電層を用いた場合においても、同様の傾向となる。 FIG. 9 is a diagram showing the relationship between the fractional bandwidth and the amount of phase rotation of the spurious impedance normalized by 180 degrees as the magnitude of the spurious when a large number of acoustic wave resonators are configured according to this embodiment. be. The ratio band was adjusted by changing the film thickness of the piezoelectric layer and the dimensions of the electrodes. Also, FIG. 9 shows the results when a Z-cut LiNbO 3 piezoelectric layer is used, but the same tendency is obtained when piezoelectric layers with other cut angles are used.
　図９中の楕円Ｊで囲まれている領域では、スプリアスが１．０と大きくなっている。図９から明らかなように、比帯域が０．１７を超えると、すなわち１７％を超えると、スプリアスレベルが１以上の大きなスプリアスが、比帯域を構成するパラメータを変化させたとしても、通過帯域内に現れる。すなわち、図８に示す共振特性のように、矢印Ｂで示す大きなスプリアスが帯域内に現れる。よって、比帯域は１７％以下であることが好ましい。この場合には、圧電層２の膜厚や電極３，４の寸法などを調整することにより、スプリアスを小さくすることができる。 In the area surrounded by ellipse J in FIG. 9, the spurious is as large as 1.0. As is clear from FIG. 9, when the fractional band exceeds 0.17, that is, when it exceeds 17%, a large spurious with a spurious level of 1 or more changes the parameters constituting the fractional band, even if the passband appear within. That is, as in the resonance characteristics shown in FIG. 8, a large spurious component indicated by arrow B appears within the band. Therefore, the specific bandwidth is preferably 17% or less. In this case, by adjusting the film thickness of the piezoelectric layer 2 and the dimensions of the electrodes 3 and 4, the spurious response can be reduced.
　図１０は、ｄ／２ｐと、メタライゼーション比ＭＲと、比帯域との関係を示す図である。上記弾性波装置において、ｄ／２ｐと、ＭＲが異なる様々な弾性波装置を構成し、比帯域を測定した。図１０の破線Ｄの右側のハッチングを付して示した部分が、比帯域が１７％以下の領域である。このハッチングを付した領域と、付していない領域との境界は、ＭＲ＝３．５（ｄ／２ｐ）＋０．０７５で表される。すなわち、ＭＲ＝１．７５（ｄ／ｐ）＋０．０７５である。従って、好ましくは、ＭＲ≦１．７５（ｄ／ｐ）＋０．０７５である。その場合には、比帯域を１７％以下としやすい。より好ましくは、図１０中の一点鎖線Ｄ１で示すＭＲ＝３．５（ｄ／２ｐ）＋０．０５の右側の領域である。すなわち、ＭＲ≦１．７５（ｄ／ｐ）＋０．０５であれば、比帯域を確実に１７％以下にすることができる。 FIG. 10 is a diagram showing the relationship between d/2p, metallization ratio MR, and fractional bandwidth. In the elastic wave device described above, various elastic wave devices having different d/2p and MR were constructed, and the fractional bandwidth was measured. The hatched portion on the right side of the dashed line D in FIG. 10 is the area where the fractional bandwidth is 17% or less. The boundary between the hatched area and the non-hatched area is expressed by MR=3.5(d/2p)+0.075. That is, MR=1.75(d/p)+0.075. Therefore, preferably MR≤1.75(d/p)+0.075. In that case, it is easy to set the fractional bandwidth to 17% or less. More preferably, it is the area on the right side of MR=3.5(d/2p)+0.05 indicated by the dashed-dotted line D1 in FIG. That is, if MR≤1.75(d/p)+0.05, the fractional bandwidth can be reliably reduced to 17% or less.
　図１１は、ｄ／ｐを限りなく０に近づけた場合のＬｉＮｂＯ3のオイラー角（０°，θ，ψ）に対する比帯域のマップを示す図である。図１１のハッチングを付して示した部分が、少なくとも５％以上の比帯域が得られる領域であり、当該領域の範囲を近似すると、下記の式（１）、式（２）及び式（３）で表される範囲となる。 FIG. 11 is a diagram showing a map of fractional bandwidth with respect to Euler angles (0°, θ, ψ) of LiNbO 3 when d/p is brought infinitely close to 0. In FIG. The hatched portion in FIG. 11 is a region where a fractional bandwidth of at least 5% or more is obtained, and when the range of the region is approximated, the following formulas (1), (2) and (3) ).
　（０°±１０°，０°～２０°，任意のψ）　　…式（１） (0°±10°, 0° to 20°, arbitrary ψ) ……Equation (1)
　（０°±１０°，２０°～８０°，０°～６０°（１－（θ－５０）2／９００）1/2）　または　（０°±１０°，２０°～８０°，［１８０°－６０°（１－（θ－５０）2／９００）1/2］～１８０°）　　…式（２） (0°±10°, 20° to 80°, 0° to 60° (1-(θ-50) 2 /900) 1/2 ) or (0°±10°, 20° to 80°, [180 °-60° (1-(θ-50) 2 /900) 1/2 ] ~ 180°) Equation (2)
　（０°±１０°，［１８０°－３０°（１－（ψ－９０）2／８１００）1/2］～１８０°，任意のψ）　　…式（３） (0°±10°, [180°-30°(1-(ψ-90) 2 /8100) 1/2 ]~180°, arbitrary ψ) Equation (3)
　従って、上記式（１）、式（２）または式（３）のオイラー角範囲の場合、比帯域を十分に広くすることができ、好ましい。 Therefore, in the case of the Euler angle range of formula (1), formula (2), or formula (3), the fractional band can be sufficiently widened, which is preferable.
　図１２は、本開示の一実施形態の変形例に係る弾性波装置を説明するための部分切り欠き斜視図である。弾性波装置８１は、支持基板８２を有する。支持基板８２には、上面に開いた凹部が設けられている。支持基板８２上に圧電層８３が積層されている。それによって、空洞部９が構成されている。この空洞部９の上方において圧電層８３上に、ＩＤＴ電極８４が設けられている。ＩＤＴ電極８４の弾性波伝搬方向両側に、反射器８５，８６が設けられている。図１２において、空洞部９の外周縁を破線で示す。ここでは、ＩＤＴ電極８４は、第１，第２のバスバー８４ａ，８４ｂと、複数本の第１の電極指としての電極８４ｃ及び複数本の第２の電極指としての電極８４ｄとを有する。複数本の電極８４ｃは、第１のバスバー８４ａに接続されている。複数本の電極８４ｄは、第２のバスバー８４ｂに接続されている。複数本の電極８４ｃと、複数本の電極８４ｄとは間挿し合っている。 FIG. 12 is a partially cutaway perspective view for explaining an elastic wave device according to a modification of one embodiment of the present disclosure. The elastic wave device 81 has a support substrate 82 . The support substrate 82 is provided with a concave portion that is open on the upper surface. A piezoelectric layer 83 is laminated on the support substrate 82 . A hollow portion 9 is thereby formed. An IDT electrode 84 is provided on the piezoelectric layer 83 above the cavity 9 . Reflectors 85 and 86 are provided on both sides of the IDT electrode 84 in the elastic wave propagation direction. In FIG. 12, the outer periphery of the hollow portion 9 is indicated by broken lines. Here, the IDT electrode 84 has first and second bus bars 84a and 84b, an electrode 84c as a plurality of first electrode fingers and an electrode 84d as a plurality of second electrode fingers. The multiple electrodes 84c are connected to the first bus bar 84a. The multiple electrodes 84d are connected to the second bus bar 84b. The multiple electrodes 84c and the multiple electrodes 84d are interposed.
　弾性波装置８１では、上記空洞部９上のＩＤＴ電極８４に、交流電界を印加することにより、板波としてのラム波が励振される。そして、反射器８５，８６が両側に設けられているため、上記ラム波による共振特性を得ることができる。 In the elastic wave device 81, a Lamb wave as a plate wave is excited by applying an AC electric field to the IDT electrodes 84 on the cavity 9. Since the reflectors 85 and 86 are provided on both sides, the resonance characteristics due to the Lamb wave can be obtained.
　このように、本開示の弾性波装置は、板波を利用するものであってもよい。 Thus, the elastic wave device of the present disclosure may utilize plate waves.
　図１３および図１４を参照して、本開示の一実施形態の弾性波装置１について説明する。本実施形態においては、第１～第４の態様の弾性波装置と重複する内容については適宜、説明を省略する。以下、第１～第４の態様の弾性波装置について説明した内容を適用することができる。 An elastic wave device 1 according to an embodiment of the present disclosure will be described with reference to FIGS. 13 and 14. FIG. In the present embodiment, the description of the content overlapping with the elastic wave devices of the first to fourth aspects will be omitted as appropriate. The contents described below for the elastic wave devices of the first to fourth aspects can be applied.
　図１３および図１４に示すように、弾性波装置１は、支持基板１１０と、圧電層２と、機能電極１２０とを備える。支持基板１１０は、例えば、支持部材８のみで構成されている。圧電層２は、支持部材８上に設けられている。機能電極１２０、圧電層２上に設けられている。 As shown in FIGS. 13 and 14, the acoustic wave device 1 includes a support substrate 110, a piezoelectric layer 2, and functional electrodes 120. The support substrate 110 is composed only of the support member 8, for example. The piezoelectric layer 2 is provided on the support member 8 . A functional electrode 120 is provided on the piezoelectric layer 2 .
　支持基板１１０の内部には、空洞部９が設けられている。空洞部９は、支持基板１１０および圧電層２の積層方向（例えば、Ｚ方向）に沿って見た平面視において、機能電極１２０の一部と重なる位置に設けられている。 A hollow portion 9 is provided inside the support substrate 110 . The hollow portion 9 is provided at a position overlapping with a portion of the functional electrode 120 in plan view along the stacking direction (for example, Z direction) of the support substrate 110 and the piezoelectric layer 2 .
　空洞部９には、第１部材１４１および第２部材１４２が、空洞部９に積層方向Ｚに交差する第１方向（例えば、Ｘ方向）に間隔を空けてそれぞれ設けられている。第１部材１４１および第２部材１４２の各々は、積層方向Ｚにおいて圧電層２を支持して、後述するメンブレン部２１の変形を防止可能に構成されている。一例として、第１部材１４１および第２部材１４２の各々は、積層方向Ｚおよび第１方向Ｘに交差する第２方向（例えば、Ｙ方向）に延びる略四角柱形状を有している。 A first member 141 and a second member 142 are provided in the hollow portion 9 with a gap therebetween in a first direction (for example, the X direction) intersecting the stacking direction Z in the hollow portion 9 . Each of the first member 141 and the second member 142 is configured to support the piezoelectric layer 2 in the stacking direction Z and prevent deformation of the membrane portion 21, which will be described later. As an example, each of the first member 141 and the second member 142 has a substantially quadrangular prism shape extending in a second direction (eg, Y direction) that intersects the stacking direction Z and the first direction X. As shown in FIG.
　圧電層２は、メンブレン部２１を有している。メンブレン部２１は、例えば、積層方向Ｚにおいて少なくとも部分的に空洞部９を重なる圧電層２の一部を構成している。メンブレン部２１には、機能電極１２０が位置し、励振領域を形成する。つまり、第１部材１４１および第２部材１４２は、積層方向Ｚに沿って見た場合に、励振領域と重なるように空洞部９に配置されている。 The piezoelectric layer 2 has a membrane portion 21 . The membrane part 21 constitutes a part of the piezoelectric layer 2 that at least partially overlaps the hollow part 9 in the stacking direction Z, for example. A functional electrode 120 is positioned on the membrane portion 21 to form an excitation region. That is, the first member 141 and the second member 142 are arranged in the hollow portion 9 so as to overlap with the excitation region when viewed along the stacking direction Z. As shown in FIG.
　機能電極１２０は、例えば、複数の電極指１２１、１２２を有するＩＤＴ電極であり、第２方向Ｙにおいて間隔を空けて配置された２つの配線電極１３１、１３２の間に位置している。機能電極１２０の複数の電極指１２１、１２２は、それぞれ第２方向Ｙに沿って延びており、第１方向Ｘに沿って隙間を空けて位置している。一例として、電極指１２１は、配線電極１３１に接続され、電極指１２２は、配線電極１３２に接続されている。 The functional electrode 120 is, for example, an IDT electrode having a plurality of electrode fingers 121 and 122, and is positioned between two wiring electrodes 131 and 132 spaced apart in the second direction Y. The plurality of electrode fingers 121 and 122 of the functional electrode 120 each extend along the second direction Y and are positioned along the first direction X with a gap therebetween. As an example, electrode finger 121 is connected to wiring electrode 131 and electrode finger 122 is connected to wiring electrode 132 .
　機能電極１２０は、積層方向Ｚに沿って見た場合、第１部材１４１および第２部材１４２の間に位置する電極指１２１、１２２の数が「１０以上」になるように構成されている。図１３および図１４の弾性波装置１は、第１部材１４１および第２部材１４２の間に位置する電極指１２１、１２２の数が「１０」の機能電極１２０を備えている。 The functional electrode 120 is configured such that the number of electrode fingers 121 and 122 positioned between the first member 141 and the second member 142 is "10 or more" when viewed along the stacking direction Z. The elastic wave device 1 of FIGS. 13 and 14 includes a functional electrode 120 having ten electrode fingers 121 and 122 located between a first member 141 and a second member 142 .
　本実施形態では、一例として、積層方向Ｚに沿って見た場合に、第１部材１４１の中心線Ｌ１と第２部材１４２の中心線Ｌ２との間に位置する電極指１２１、１２２（中心線Ｌ１、Ｌ２上に位置する電極指１２１、１２２を含む）を「第１部材１４１および第２部材１４２の間に位置する電極指１２１、１２２」としている。中心線Ｌ１は、第１部材１４１の第１方向Ｘの中心を通り第２方向Ｙに延びる仮想直線であり、中心線Ｌ２は、第２部材１４２の第１方向Ｘの中心を通り第２方向Ｙに延びる仮想直線であるとする。 In the present embodiment, as an example, when viewed along the stacking direction Z, the electrode fingers 121 and 122 (the center line including the electrode fingers 121 and 122 positioned on L1 and L2) are referred to as " electrode fingers 121 and 122 positioned between the first member 141 and the second member 142". A center line L1 is an imaginary straight line passing through the center of the first member 141 in the first direction X and extending in the second direction Y. A center line L2 is a virtual straight line passing through the center of the second member 142 in the first direction X in the second direction. Suppose it is an imaginary straight line extending in Y.
　図１５に示す弾性波装置１００におけるリターンロスと周波数との関係を図１６に示す。図１６の実線で囲んだ部分２００における機能電極１２０の電極指１２１、１２２の数とリターンロスとの関係を図１７に示す。図１５では、弾性波装置１００の空洞部９、圧電層２のメンブレン部２１、機能電極１２０および部材１４４以外の構成は省略している。図１５の弾性波装置１００は、第１部材１４１および第２部材１４２の代わりに部材１４４が空洞部９に設けられている点と、機能電極１２０の電極指１２１、１２２の数とを除いて、弾性波装置１と同じ構成を有している。部材１４４は、空洞部９の第１方向Ｘにおける略中央に位置している。図１７の「電極指の数」は、部材１４４と空洞部９の第１方向Ｘの一端との間の電極指１２１、１２２の数Ｎ（図１５参照）を示す。図１７に示すように、電極指１２１、１２２の数が１０以上になると、リターンロスが良くなることが分かる。 FIG. 16 shows the relationship between return loss and frequency in the elastic wave device 100 shown in FIG. FIG. 17 shows the relationship between the number of electrode fingers 121 and 122 of the functional electrode 120 and the return loss in the portion 200 surrounded by the solid line in FIG. 15 omits components other than the hollow portion 9 of the elastic wave device 100, the membrane portion 21 of the piezoelectric layer 2, the functional electrode 120, and the member 144. FIG. Elastic wave device 100 of FIG. , has the same configuration as the elastic wave device 1 . The member 144 is positioned substantially in the center of the cavity 9 in the first direction X. As shown in FIG. “Number of electrode fingers” in FIG. 17 indicates the number N of electrode fingers 121 and 122 between the member 144 and one end of the cavity 9 in the first direction X (see FIG. 15). As shown in FIG. 17, it can be seen that the return loss improves when the number of electrode fingers 121 and 122 is 10 or more.
　弾性波装置１は、支持基板１１０と、支持基板１１０上に設けられた圧電層２と、圧電層２上に設けられた機能電極１２０と、空洞部９と、第１部材１４１および第２部材１４２とを備える。空洞部９は、支持基板１１０の内部に設けられ、支持基板１１０および圧電層２の積層方向Ｚに沿って見た平面視において機能電極１２０の一部と重なる位置にある。第１部材１４１および第２部材１４２は、空洞部９に第１方向Ｘに間隔を空けてそれぞれ設けられ、積層方向Ｚにおいて圧電層２をそれぞれ支持する。機能電極１２０が、第１方向Ｘに沿って間隔を空けて位置する複数の電極指１２１、１２２を有し、積層方向Ｚに沿って見た場合、第１部材１４１および第２部材１４２の間に位置する電極指１２１、１２２の数が１０以上である。このような構成により、メンブレン部２１の変形を防止しつつ、良好なリターンロスを維持できる弾性波装置１を実現できる。 The elastic wave device 1 includes a supporting substrate 110, a piezoelectric layer 2 provided on the supporting substrate 110, a functional electrode 120 provided on the piezoelectric layer 2, a hollow portion 9, a first member 141 and a second member. 142. The hollow portion 9 is provided inside the support substrate 110 and is positioned so as to partially overlap the functional electrode 120 in plan view along the stacking direction Z of the support substrate 110 and the piezoelectric layer 2 . The first member 141 and the second member 142 are provided in the hollow portion 9 with a gap therebetween in the first direction X, and support the piezoelectric layers 2 in the stacking direction Z, respectively. The functional electrode 120 has a plurality of electrode fingers 121 and 122 spaced apart along the first direction X, and when viewed along the stacking direction Z, between the first member 141 and the second member 142 The number of electrode fingers 121 and 122 positioned at 10 or more. With such a configuration, it is possible to realize the acoustic wave device 1 capable of maintaining a good return loss while preventing deformation of the membrane portion 21 .
　本実施形態の弾性波装置１は、次のように構成することもできる。 The elastic wave device 1 of this embodiment can also be configured as follows.
　メンブレン部２１は、積層方向Ｚに沿って見た場合における第１部材１４１および第２部材１４２間の電極指１２１、１２２の数が３０を超えると積層方向Ｚにおける変位が大きくなる。このため、積層方向Ｚに沿って見た場合における第１部材１４１および第２部材１４２間の電極指１２１、１２２の数を３０以下にすることで、メンブレン部２１の変形をより確実に防止できる。 When the number of electrode fingers 121 and 122 between the first member 141 and the second member 142 exceeds 30 when viewed along the stacking direction Z, the membrane part 21 undergoes a large displacement in the stacking direction Z. Therefore, by setting the number of electrode fingers 121 and 122 between the first member 141 and the second member 142 to 30 or less when viewed along the stacking direction Z, deformation of the membrane portion 21 can be more reliably prevented. .
　第１部材１４１および第２部材１４２の間に位置する電極指１２１、１２２の数は「１０以上」であればよい。一例として、第１部材１４１および第２部材１４２の間に位置する電極指１２１、１２２の数が「３０」の機能電極１２０を備える弾性波装置１を図１８に示す。図１８の弾性波装置１は、積層方向Ｚに沿って見た場合に、第１部材１４１および第２部材１４２の各々が湾曲した少なくとも１つの角部１４３を有している。一例として、図１８の弾性波装置１では、第１部材１４１および第２部材１４２の各々における４つの角部１４３が全て湾曲している。角部１４３が鋭角である場合、角部１４３に応力が集中するため、メンブレン部２１が破壊されてしまう可能性が考えられる。第１部材１４１および第２部材１４２が湾曲した角部１４３を有することで、角部１４３の応力が分散され、メンブレン部２１の破壊を防止できる。 The number of electrode fingers 121 and 122 positioned between the first member 141 and the second member 142 should be "10 or more". As an example, FIG. 18 shows an elastic wave device 1 including a functional electrode 120 having “30” electrode fingers 121 and 122 located between a first member 141 and a second member 142 . In the elastic wave device 1 of FIG. 18, each of the first member 141 and the second member 142 has at least one curved corner portion 143 when viewed along the stacking direction Z. As shown in FIG. As an example, in elastic wave device 1 of FIG. 18, all four corners 143 of each of first member 141 and second member 142 are curved. If the corner portion 143 has an acute angle, the stress concentrates on the corner portion 143, and the membrane portion 21 may be destroyed. Since the first member 141 and the second member 142 have the curved corners 143 , the stress of the corners 143 is dispersed and the destruction of the membrane part 21 can be prevented.
　図１９に示すように、電極指１２１、１２２は、積層方向Ｚに沿って見た場合に、第１部材１４１および第２部材１４２と重ならないように配置されていてもよい。つまり、電極指１２１、１２２は、積層方向Ｚにおいて第１部材１４１または第２部材１４２と重なる位置にあってもよいし、なくてもよい。 As shown in FIG. 19, the electrode fingers 121 and 122 may be arranged so as not to overlap the first member 141 and the second member 142 when viewed along the stacking direction Z. That is, the electrode fingers 121 and 122 may or may not overlap the first member 141 or the second member 142 in the stacking direction Z.
　弾性波装置１は、犠牲層を用いて空洞部９を形成する方法、または、支持基板１１０を裏面からエッチングする方法等の任意の方法を用いて製造できる。 The elastic wave device 1 can be manufactured using any method such as a method of forming the cavity 9 using a sacrificial layer or a method of etching the support substrate 110 from the back surface.
　支持基板１１０は、支持部材８のみで構成されている場合に限らず、支持部材８と、支持部材８上に設けられた絶縁層（接合層）７とを含むように構成されていてもよい。 The support substrate 110 is not limited to being composed only of the support member 8 , and may be configured to include the support member 8 and the insulating layer (bonding layer) 7 provided on the support member 8 . .
　第１～第４の態様の弾性波装置に、本開示の弾性波装置１の構成の少なくとも一部を追加してもよいし、本開示の弾性波装置１に、第１～第４態様の弾性波装置の構成の少なくとも一部を追加してもよい。 At least part of the configuration of the elastic wave device 1 of the present disclosure may be added to the elastic wave devices of the first to fourth aspects, or the elastic wave device 1 of the present disclosure may be added to the elastic wave devices of the first to fourth aspects. At least part of the configuration of the acoustic wave device may be added.
　以上、図面を参照して本開示における種々の実施形態を詳細に説明したが、最後に、本開示の種々の態様について説明する。 Various embodiments of the present disclosure have been described in detail above with reference to the drawings. Finally, various aspects of the present disclosure will be described.
　第１態様の弾性波装置は、
　支持基板と、
　前記支持基板上に設けられた圧電体層と、
　前記圧電体層上に設けられた機能電極と、
　前記支持基板の内部に設けられ、前記支持基板および前記圧電体層の積層方向に沿って見た平面視において前記機能電極の一部と重なる位置にある空洞部と、
　前記空洞部に前記積層方向に交差する方向に間隔を空けてそれぞれ設けられ、前記積層方向において前記圧電体層をそれぞれ支持する第１部材および第２部材と
を備え、
　前記機能電極が、
　前記積層方向に交差する方向に沿って間隔を空けて位置する複数の電極指を有し、
　前記積層方向に沿って見た場合、前記第１部材および前記第２部材の間に位置する前記電極指の数が１０以上である。 The elastic wave device of the first aspect is
a support substrate;
a piezoelectric layer provided on the support substrate;
a functional electrode provided on the piezoelectric layer;
a hollow portion provided inside the support substrate and overlapping with a part of the functional electrode in a plan view along the stacking direction of the support substrate and the piezoelectric layer;
a first member and a second member provided in the cavity in a direction intersecting the stacking direction with a gap therebetween and supporting the piezoelectric layers in the stacking direction;
The functional electrode is
Having a plurality of electrode fingers spaced apart along a direction intersecting the stacking direction,
When viewed along the stacking direction, the number of electrode fingers positioned between the first member and the second member is 10 or more.
　第２態様の弾性波装置は、第１態様の弾性波装置において、
　前記積層方向に沿って見た場合、前記第１部材および前記第２部材の間に位置する前記電極指の数が３０以下である。 The elastic wave device of the second aspect is the elastic wave device of the first aspect,
When viewed along the stacking direction, the number of electrode fingers positioned between the first member and the second member is 30 or less.
　第３態様の弾性波装置は、第１態様または第２態様の弾性波装置において
　前記積層方向に沿って見た場合、前記第１部材および前記第２部材の各々が湾曲した角部を有している。 A third aspect of the elastic wave device is the elastic wave device of the first aspect or the second aspect, wherein each of the first member and the second member has a curved corner when viewed along the stacking direction. ing.
　第４態様の弾性波装置は、第１態様～第３態様のいずれかの弾性波装置において、
　前記圧電体層が、Ｚカットのニオブ酸リチウムまたはタンタル酸リチウムを含む。 The elastic wave device of the fourth aspect is the elastic wave device of any one of the first to third aspects,
The piezoelectric layer includes Z-cut lithium niobate or lithium tantalate.
　第５態様の弾性波装置は、第１態様～第４態様のいずれかの弾性波装置において、
　前記機能電極がＩＤＴ電極である。 The elastic wave device of the fifth aspect is the elastic wave device of any one of the first to fourth aspects,
The functional electrodes are IDT electrodes.
　第６態様の弾性波装置は、第５態様の弾性波装置において、
　前記圧電体層が、ニオブ酸リチウムまたはタンタル酸リチウムを含み、
　前記ＩＤＴ電極が、前記積層方向に交差する方向において対向する第１電極指および第２電極指を有し、
　前記第１電極指および前記第２電極指は隣り合う電極同士であり、
　前記圧電体層の厚みをｄ、前記第１電極指および前記第２電極指との中心間距離をｐとした場合、ｄ／ｐが０．５以下である。 The elastic wave device of the sixth aspect is the elastic wave device of the fifth aspect,
the piezoelectric layer contains lithium niobate or lithium tantalate,
the IDT electrode has a first electrode finger and a second electrode finger facing each other in a direction intersecting the stacking direction;
the first electrode finger and the second electrode finger are adjacent electrodes;
Where d is the thickness of the piezoelectric layer and p is the center-to-center distance between the first electrode finger and the second electrode finger, d/p is 0.5 or less.
　第７態様の弾性波装置は、第６態様の弾性波装置において、
　ｄ／ｐが０．２４以下である。 The elastic wave device of the seventh aspect is the elastic wave device of the sixth aspect,
d/p is 0.24 or less.
　第８様の弾性波装置は、第６態様または第７態様の弾性波装置において、
　前記積層方向に交差する方向において、前記第１電極指および前記第２電極指が重なり合っている領域である励振領域に対する、前記励振領域内の前記第１電極指および前記第２電極指の面積の割合であるメタライゼーション比ＭＲが、ＭＲ≦１．７５（ｄ／ｐ）＋０．０７５を満たす。 The eighth-like elastic wave device is the elastic wave device of the sixth aspect or the seventh aspect,
the area of the first electrode fingers and the second electrode fingers in the excitation region with respect to the excitation region, which is the region where the first electrode fingers and the second electrode fingers overlap in the direction intersecting the stacking direction; The metallization ratio MR, which is a ratio, satisfies MR≦1.75(d/p)+0.075.
　第９態様の弾性波装置は、第６態様～第８態様のいずれかの弾性波装置において、
　前記ニオブ酸リチウムまたはタンタル酸リチウムのオイラー角（φ，θ，ψ）が、以下の式（１）、式（２）または式（３）の範囲にある。
　（０°±１０°，０°～２０°，任意のψ）　　…式（１）
　（０°±１０°，２０°～８０°，０°～６０°（１－（θ－５０）2／９００）1/2）　または　（０°±１０°，２０°～８０°，［１８０°－６０°（１－（θ－５０）2／９００）1/2］～１８０°）　　…式（２）
　（０°±１０°，［１８０°－３０°（１－（ψ－９０）2／８１００）1/2］～１８０°，任意のψ）　　…式（３） The elastic wave device of the ninth aspect is the elastic wave device of any one of the sixth aspect to the eighth aspect,
The Euler angles (φ, θ, ψ) of the lithium niobate or lithium tantalate are within the range of the following formula (1), formula (2) or formula (3).
(0°±10°, 0° to 20°, arbitrary ψ) Equation (1)
(0°±10°, 20° to 80°, 0° to 60° (1-(θ-50) 2 /900) 1/2 ) or (0°±10°, 20° to 80°, [180 °-60° (1-(θ-50) 2 /900) 1/2 ] ~ 180°) Equation (2)
(0°±10°, [180°-30°(1-(ψ-90) 2 /8100) 1/2 ]~180°, arbitrary ψ) Equation (3)
　第１０態様の弾性波装置は、第５態様～第９態様のいずれかの弾性波装置において、
　前記圧電体層が、ニオブ酸リチウムまたはタンタル酸リチウムを含み、
　厚み滑りモードのバルク波を利用可能に構成されている。 The elastic wave device of the tenth aspect is the elastic wave device of any one of the fifth to ninth aspects,
the piezoelectric layer contains lithium niobate or lithium tantalate,
It is configured to be able to utilize bulk waves in the thickness-shlip mode.
　第１１態様の弾性波装置は、第１態様～第５態様のいずれかの弾性波装置において、
　板波を利用可能に構成されている。 The elastic wave device of the eleventh aspect is the elastic wave device of any one of the first to fifth aspects,
It is configured to be able to use plate waves.
　前記様々な実施形態または変形例のうちの任意の実施形態または変形例を適宜組み合わせることにより、それぞれの有する効果を奏するようにすることができる。また、実施形態同士の組み合わせまたは実施例同士の組み合わせまたは実施形態と実施例との組み合わせが可能であると共に、異なる実施形態または実施例の中の特徴同士の組み合わせも可能である。 By appropriately combining any of the various embodiments or modifications described above, the respective effects can be achieved. In addition, combinations of embodiments, combinations of examples, or combinations of embodiments and examples are possible, as well as combinations of features in different embodiments or examples.
　本開示は、添付図面を参照しながら好ましい実施形態に関連して充分に記載されているが、この技術の熟練した人々にとっては種々の変形や修正は明白である。そのような変形や修正は、添付した請求の範囲による本開示の範囲から外れない限りにおいて、その中に含まれると理解されるべきである。 Although the present disclosure has been fully described in connection with preferred embodiments with reference to the accompanying drawings, various variations and modifications will be apparent to those skilled in the art. Such variations and modifications are to be understood as included therein insofar as they do not depart from the scope of the present disclosure by the appended claims.

Claims (11)

  1. 　支持基板と、
    　前記支持基板上に設けられた圧電体層と、
    　前記圧電体層上に設けられた機能電極と、
    　前記支持基板の内部に設けられ、前記支持基板および前記圧電体層の積層方向に沿って見た平面視において前記機能電極の一部と重なる位置にある空洞部と、
    　前記空洞部に前記積層方向に交差する方向に間隔を空けてそれぞれ設けられ、前記積層方向において前記圧電体層をそれぞれ支持する第１部材および第２部材と
    を備え、
    　前記機能電極が、
    　前記積層方向に交差する方向に沿って間隔を空けて位置する複数の電極指を有し、
    　前記積層方向に沿って見た場合、前記第１部材および前記第２部材の間に位置する前記電極指の数が１０以上である、弾性波装置。     a support substrate;
    a piezoelectric layer provided on the support substrate;
    a functional electrode provided on the piezoelectric layer;
    a hollow portion provided inside the support substrate and overlapping with a part of the functional electrode in a plan view along the stacking direction of the support substrate and the piezoelectric layer;
    a first member and a second member provided in the cavity in a direction intersecting the stacking direction with a gap therebetween and supporting the piezoelectric layers in the stacking direction;
    The functional electrode is
    Having a plurality of electrode fingers spaced apart along a direction intersecting the stacking direction,
    The elastic wave device, wherein the number of the electrode fingers positioned between the first member and the second member is 10 or more when viewed along the stacking direction.
  2. 　前記積層方向に沿って見た場合、前記第１部材および前記第２部材の間に位置する前記電極指の数が３０以下である、請求項１に記載の弾性波装置。 The elastic wave device according to claim 1, wherein the number of said electrode fingers located between said first member and said second member is 30 or less when viewed along said stacking direction.
  3. 　前記積層方向に沿って見た場合、前記第１部材および前記第２部材の各々が湾曲した角部を有している、請求項１または２に記載の弾性波装置。 The elastic wave device according to claim 1 or 2, wherein each of said first member and said second member has a curved corner when viewed along said stacking direction.
  4. 　前記圧電体層が、Ｚカットのニオブ酸リチウムまたはタンタル酸リチウムを含む、請求項１から３のいずれか１つに記載の弾性波装置。 The elastic wave device according to any one of claims 1 to 3, wherein the piezoelectric layer contains Z-cut lithium niobate or lithium tantalate.
  5. 　前記機能電極がＩＤＴ電極である、請求項１から４のいずれか１つに記載の弾性波装置。 The elastic wave device according to any one of claims 1 to 4, wherein the functional electrodes are IDT electrodes.
  6. 　前記圧電体層が、ニオブ酸リチウムまたはタンタル酸リチウムを含み、
    　前記ＩＤＴ電極が、前記積層方向に交差する方向において対向する第１電極指および第２電極指を有し、
    　前記第１電極指および前記第２電極指は隣り合う電極同士であり、
    　前記圧電体層の厚みをｄ、前記第１電極指および前記第２電極指との中心間距離をｐとした場合、ｄ／ｐが０．５以下である、請求項５に記載の弾性波装置。     the piezoelectric layer contains lithium niobate or lithium tantalate,
    the IDT electrode has a first electrode finger and a second electrode finger facing each other in a direction intersecting the stacking direction;
    the first electrode finger and the second electrode finger are adjacent electrodes;
    6. The elastic wave according to claim 5, wherein d/p is 0.5 or less, where d is the thickness of the piezoelectric layer and p is the center-to-center distance between the first electrode finger and the second electrode finger. Device.
  7. 　ｄ／ｐが０．２４以下である、請求項６に記載の弾性波装置。 The elastic wave device according to claim 6, wherein d/p is 0.24 or less.
  8. 　前記積層方向に交差する方向において、前記第１電極指および前記第２電極指が重なり合っている領域である励振領域に対する、前記励振領域内の前記第１電極指および前記第２電極指の面積の割合であるメタライゼーション比ＭＲが、ＭＲ≦１．７５（ｄ／ｐ）＋０．０７５を満たす、請求項６または７に記載の弾性波装置。 the area of the first electrode fingers and the second electrode fingers in the excitation region with respect to the excitation region, which is the region where the first electrode fingers and the second electrode fingers overlap in the direction intersecting the stacking direction; 8. The elastic wave device according to claim 6, wherein a metallization ratio MR, which is a ratio, satisfies MR≦1.75(d/p)+0.075.
  9. 　前記ニオブ酸リチウムまたはタンタル酸リチウムのオイラー角（φ，θ，ψ）が、以下の式（１）、式（２）または式（３）の範囲にある、請求項６から８のいずれか１つに記載の弾性波装置。
    　（０°±１０°，０°～２０°，任意のψ）　　…式（１）
    　（０°±１０°，２０°～８０°，０°～６０°（１－（θ－５０）2／９００）1/2）　または　（０°±１０°，２０°～８０°，［１８０°－６０°（１－（θ－５０）2／９００）1/2］～１８０°）　　…式（２）
    　（０°±１０°，［１８０°－３０°（１－（ψ－９０）2／８１００）1/2］～１８０°，任意のψ）　　…式（３）     Any one of claims 6 to 8, wherein the Euler angles (φ, θ, ψ) of the lithium niobate or lithium tantalate are in the range of the following formula (1), formula (2) or formula (3) The elastic wave device according to 1.
    (0°±10°, 0° to 20°, arbitrary ψ) Equation (1)
    (0°±10°, 20° to 80°, 0° to 60° (1-(θ-50) 2 /900) 1/2 ) or (0°±10°, 20° to 80°, [180 °-60° (1-(θ-50) 2 /900) 1/2 ] ~ 180°) Equation (2)
    (0°±10°, [180°-30°(1-(ψ-90) 2 /8100) 1/2 ]~180°, arbitrary ψ) Equation (3)
  10. 　前記圧電体層が、ニオブ酸リチウムまたはタンタル酸リチウムを含み、
    　厚み滑りモードのバルク波を利用可能に構成されている、請求項５から９のいずれか１つに記載の弾性波装置。     the piezoelectric layer contains lithium niobate or lithium tantalate,
    The elastic wave device according to any one of claims 5 to 9, configured to be able to use thickness-shear mode bulk waves.
  11. 　板波を利用可能に構成されている、請求項１から５のいずれか１つに記載の弾性波装置。 The elastic wave device according to any one of claims 1 to 5, configured to be able to use plate waves.
PCT/JP2023/008059 2022-03-04 2023-03-03 Elastic wave device WO2023167316A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016052129A1 (en) * 2014-09-30 2016-04-07 株式会社村田製作所 Acoustic wave device and method for manufacturing same
WO2021060513A1 (en) * 2019-09-27 2021-04-01 株式会社村田製作所 Elastic wave device
WO2021187397A1 (en) * 2020-03-16 2021-09-23 株式会社村田製作所 Elastic wave device
WO2022102719A1 (en) * 2020-11-13 2022-05-19 株式会社村田製作所 Elastic wave device

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016052129A1 (en) * 2014-09-30 2016-04-07 株式会社村田製作所 Acoustic wave device and method for manufacturing same
WO2021060513A1 (en) * 2019-09-27 2021-04-01 株式会社村田製作所 Elastic wave device
WO2021187397A1 (en) * 2020-03-16 2021-09-23 株式会社村田製作所 Elastic wave device
WO2022102719A1 (en) * 2020-11-13 2022-05-19 株式会社村田製作所 Elastic wave device

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