WO2023085364A1 - Elastic wave device - Google Patents

Elastic wave device Download PDF

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Publication number
WO2023085364A1
WO2023085364A1 PCT/JP2022/041929 JP2022041929W WO2023085364A1 WO 2023085364 A1 WO2023085364 A1 WO 2023085364A1 JP 2022041929 W JP2022041929 W JP 2022041929W WO 2023085364 A1 WO2023085364 A1 WO 2023085364A1
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wave device
elastic wave
piezoelectric layer
electrodes
electrode
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PCT/JP2022/041929
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French (fr)
Japanese (ja)
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毅 山根
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株式会社村田製作所
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Publication of WO2023085364A1 publication Critical patent/WO2023085364A1/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 invention relates to elastic wave devices.
  • Acoustic wave devices with a piezoelectric layer made of lithium niobate or lithium tantalate are conventionally known.
  • Patent Document 1 discloses a support having a hollow portion, a piezoelectric substrate provided on the support so as to overlap the hollow portion, and a piezoelectric substrate on the piezoelectric substrate so as to overlap the hollow portion. and an IDT (Interdigital Transducer) electrode provided therein, wherein a Lamb wave is excited by the IDT electrode, wherein an edge portion of the hollow portion is a Lamb wave excited by the IDT electrode.
  • An acoustic wave device is disclosed that does not include a straight portion extending parallel to the propagation direction of the .
  • Patent Document 2 discloses a configuration in which a plurality of acoustic wave elements are mounted on a mounting substrate by a flip chip bonding method.
  • An object of the present invention is to provide an acoustic wave device in which an excitation unit including functional electrodes is less likely to be damaged when an acoustic wave element is mounted.
  • An elastic wave device of the present invention includes an elastic wave element, a bump electrically connected to the elastic wave element, an under bump metal layer provided between the elastic wave element and the bump, and the elastic wave element.
  • the elastic wave element includes a support substrate having a dielectric layer on one main surface, a piezoelectric layer provided on the one main surface of the support substrate, and a functional electrode provided on at least one main surface of the piezoelectric layer. , provided.
  • the wiring board is electrically connected to the acoustic wave element through the under bump metal layer and the bumps.
  • the thickness of the layer is 150 nm or more.
  • the excitation section including the functional electrodes is less likely to be damaged when the acoustic wave element is mounted.
  • FIG. 1 is a cross-sectional view schematically showing an elastic wave device according to Embodiment 1 of the present invention.
  • FIG. 2 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Embodiment 1 of the present invention.
  • FIG. 3 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to the comparative example.
  • FIG. 1 is a cross-sectional view schematically showing an elastic wave device according to Embodiment 1 of the present invention.
  • FIG. 2 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Embodiment 1 of the present invention.
  • FIG. 3 is a cross-sectional view schematically showing part of the
  • FIG. 4 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Modification 1 of the present invention.
  • FIG. 5 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Modification 2 of the present invention.
  • FIG. 6 is a schematic perspective view showing the appearance of an example of an acoustic wave device that utilizes a thickness shear mode bulk wave.
  • 7 is a plan view showing an electrode structure on the piezoelectric layer of the acoustic wave device shown in FIG. 6.
  • FIG. 8 is a cross-sectional view of a portion along line AA in FIG. 6.
  • FIG. 9 is a schematic front cross-sectional view for explaining Lamb waves propagating through the piezoelectric film of the elastic wave device.
  • FIG. 10 is a schematic front cross-sectional view for explaining thickness-shear mode bulk waves propagating in the piezoelectric layer of the acoustic wave device.
  • FIG. 11 is a diagram showing amplitude directions of bulk waves in the thickness shear mode.
  • 12 is a diagram showing an example of resonance characteristics of the acoustic wave device shown in FIG. 6.
  • FIG. 13 is a diagram showing the relationship between d/2p, where p is the center-to-center distance between adjacent electrodes and d is the thickness of the piezoelectric layer, and the fractional bandwidth of the acoustic wave device as a resonator.
  • FIG. 14 is a plan view of another example of an elastic wave device that utilizes thickness shear mode bulk waves.
  • 15 is a reference diagram showing an example of resonance characteristics of the acoustic wave device shown in FIG. 6.
  • FIG. FIG. 16 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 elastic wave resonators are configured according to the present embodiment. is.
  • FIG. 17 is a diagram showing the relationship between d/2p, metallization ratio MR, and fractional bandwidth.
  • FIG. 18 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.
  • FIG. 19 is a partially cutaway perspective view for explaining an example of an elastic wave device using Lamb waves.
  • FIG. 20 is a cross-sectional view schematically showing an example of an elastic wave device that utilizes bulk waves.
  • the elastic wave device of the present invention will be described below.
  • the piezoelectric layer is not provided in at least a portion between the bump and the support substrate in the stacking direction of the support substrate and the piezoelectric layer, and the piezoelectric layer is not provided in the portion. has a dielectric layer thickness of 150 nm or more. Since the piezoelectric layer is not provided at least partly between the bumps and the support substrate, pressure and impact during mounting are not transmitted to the piezoelectric layer, and cracking of the piezoelectric layer can be suppressed. Further, when the piezoelectric layer is not provided at least partly between the bump and the support substrate, sufficient insulation is required between the under bump metal (UBM) layer and the support substrate, but the piezoelectric layer is provided. If the thickness of the dielectric layer in the non-bonded portion is 150 nm or more, sufficient insulation can be ensured.
  • UBM under bump metal
  • a piezoelectric layer made of lithium niobate or lithium tantalate, a first electrode and a first electrode facing each other in a direction intersecting the thickness direction of the piezoelectric layer. 2 electrodes.
  • a bulk wave in a thickness-slip mode such as a thickness-slip primary mode is used.
  • the first electrode and the second electrode are adjacent electrodes, and when 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.
  • the Q value can be increased even when miniaturization is promoted.
  • Lamb waves are used as plate waves. Then, resonance characteristics due to the Lamb wave can be obtained.
  • the acoustic wave device of the present invention 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.
  • bulk waves are utilized.
  • FIG. 1 is a cross-sectional view schematically showing an elastic wave device according to Embodiment 1 of the present invention.
  • FIG. 2 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Embodiment 1 of the present invention.
  • Elastic wave device 10 shown in FIG. 13 a wiring board 14 on which the acoustic wave element 11 is mounted, and a sealing body 23 covering the acoustic wave element 11 on the wiring board 14 .
  • the acoustic wave element 11 includes a support substrate 16 having a dielectric layer 18 on one main surface, a piezoelectric layer 19 provided on the one main surface of the support substrate 16, and a functional electrode provided on one main surface of the piezoelectric layer 19. 15 and.
  • the wiring board 14 is electrically connected to the acoustic wave element 11 via the under bump metal layer 13 and the bumps 12 .
  • the piezoelectric layer 19 is not provided at least in part between the bumps 12 and the support substrate 16, and the dielectric in the portion where the piezoelectric layer 19 is not provided is reduced.
  • the thickness of layer 18 is 150 nm or more.
  • wiring electrodes electrically connected to the functional electrodes 15 are provided on one main surface of the support substrate 16 .
  • the under bump metal layer 13 is electrically connected to the wiring electrode.
  • FIG. 3 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to the comparative example.
  • the piezoelectric layer 19 is provided entirely between the bumps 12 and the supporting substrate 16 in the stacking direction of the supporting substrate 16 and the piezoelectric layer 19, the elastic wave element 11 can be bumped.
  • the piezoelectric layer 19 is mounted on the wiring board 14 via the bumps 12 , the piezoelectric layer 19 directly under the bumps 12 may crack due to pressure or impact during mounting, and the cracks may reach the excitation section including the functional electrodes 15 .
  • the piezoelectric layer 19 is not provided at least partly between the bumps 12 and the support substrate 16 in the stacking direction of the support substrate 16 and the piezoelectric layer 19. Pressure and impact during mounting are not transmitted to the piezoelectric layer 19, and cracking of the piezoelectric layer 19 can be suppressed.
  • a downward arrow in FIG. 2 represents the lamination direction of the support substrate 16 and the piezoelectric layer 19 .
  • the thickness of the dielectric layer 18 in the portion where the piezoelectric layer 19 is not provided is 150 nm or more.
  • T1 indicates the thickness of the dielectric layer 18 where the piezoelectric layer 19 is not provided. It is preferable that the thickness of the dielectric layer 18 in this portion is 150 nm or more and 5,000 nm or less. It is more preferably 1,000 nm or more and 3,000 nm or less.
  • the dielectric layer 18 is made of the same material in the portion where the piezoelectric layer 19 is provided and the portion where the piezoelectric layer 19 is not provided. As a result, it is possible to collectively form them at low cost, simply and with high accuracy.
  • the maximum thickness of the dielectric layer 18 at the portion where the piezoelectric layer 19 is provided is preferably at least twice the maximum thickness of the piezoelectric layer 19 .
  • the thickness of the dielectric layer 18 where the piezoelectric layer 19 is provided is indicated by T2
  • the thickness of the piezoelectric layer 19 is indicated by t.
  • the maximum thickness of the dielectric layer 18 in the portion where the piezoelectric layer 19 is not provided may be the same as the maximum thickness of the dielectric layer 18 in the portion where the piezoelectric layer 19 is provided. It may be less than the maximum thickness of layer 18 .
  • the shape and size of the portion where the piezoelectric layer 19 is not provided are not particularly limited.
  • the portion where the piezoelectric layer 19 is not provided between the bump 12 and the support substrate 16 may exist at only one location, or may exist at two or more locations.
  • the portion where the piezoelectric layer 19 is not provided may be between the bump 12 and the support substrate 16 in the stacking direction of the support substrate 16 and the piezoelectric layer 19, but the functional electrode 15 and the center of the bump 12 are connected.
  • a straight line is preferred. In this case, cracking of the piezoelectric layer 19 can be more effectively suppressed.
  • the piezoelectric layer 19 is not provided at least at the central portion of the bump 12 .
  • the area where the piezoelectric layer 19 is not provided is more preferably equal to or larger than the area where the bump 12 and the under bump metal layer 13 are in contact, and more preferably equal to or larger than the area where the under bump metal layer 13 is provided. Thereby, cracking of the piezoelectric layer 19 can be suppressed more sufficiently.
  • a configuration in which the piezoelectric layer 19 is not provided entirely between the under bump metal layer 13 and the support substrate 16 is one of the preferred embodiments of the present invention.
  • the dielectric layer 18 is made of silicon oxide (SiO x ), for example. In that case, dielectric layer 18 is preferably composed of SiO 2 . Thereby, the frequency temperature characteristic can be further improved.
  • the material of the dielectric layer 18 is not limited to the above, and for example, silicon nitride (Si x N y ) can also be used. In that case, dielectric layer 18 may consist of Si 3 N 4 .
  • the piezoelectric layer 19 is made of lithium niobate (LiNbO x ) or lithium tantalate (LiTaO x ), for example. In that case, the piezoelectric layer 19 may consist of LiNbO 3 or LiTaO 3 . Moreover, the piezoelectric layer 19 is preferably made of a piezoelectric single crystal. Since the single crystal of the piezoelectric material is more susceptible to cracking during mounting than the polycrystal, the technical significance of the present invention is more fully exhibited. The single crystal of the piezoelectric material can be analyzed by XRD (X-ray Diffractometer).
  • XRD is an apparatus that evaluates the crystal structure of a sample by irradiating the sample with X-rays and measuring the diffracted X-rays emitted from the sample.
  • the ability to assess the crystal structure allows one to distinguish between polymorphs of the same chemical formula, such as quartz, tridymite, cristobalite, silica glass (all chemical formulas are SiO 2 ).
  • the lattice constant and crystallinity can be evaluated by evaluating the position and width of the obtained peak.
  • the straight line connecting the functional electrode 15 and the bump 12 is preferably parallel to the crystal cleavage direction (direction parallel to the cleavage plane) of the piezoelectric layer 19 . Since cracking progresses on the crystal cleavage plane, this makes it possible to stop the progress of cracking more efficiently.
  • the support substrate 16 may or may not have a cavity.
  • the support substrate 16 may have a dielectric layer 18 on one main surface, but preferably includes a support member 17 and a dielectric layer 18 provided between the support member 17 and the piezoelectric layer 19 . .
  • the support member 17 is made of silicon (Si), for example.
  • the material of the support member 17 is not limited to the above, and examples thereof include aluminum oxide, lithium tantalate, lithium niobate, piezoelectric materials such as crystal, alumina, sapphire, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, and mullite. , various ceramics such as steatite and forsterite, dielectrics such as diamond and glass, semiconductors such as gallium nitride, and resins.
  • the wiring board 14 is electrically connected to the acoustic wave element 11 via the under bump metal layer 13 and the bumps 12 .
  • the wiring board 14 is configured by, for example, a printed wiring board.
  • the coefficient of linear expansion of the printed wiring board is, for example, about 15 ppm/°C.
  • the printed wiring board is formed of a glass cloth/epoxy resin copper-clad laminate. More specifically, the piezoelectric layer 19 of the acoustic wave element 11 is arranged with its main surface facing the wiring board 14 .
  • the acoustic wave elements 11 are mounted on the external terminals 21 of the wiring board 14 via the bumps 12 . Thereby, a space is formed between the one main surface of the piezoelectric layer 19 and the wiring substrate 14 .
  • the functional electrode 15 is provided between one main surface of the piezoelectric layer 19 and the wiring board 14 . More specifically, the elastic wave element 11 is laminated on the wiring substrate 14 in the order of the external terminals 21, the bumps 12, the under bump metal layer 13, the piezoelectric layer 19, and the support substrate 16. FIG.
  • the bumps 12 can be made of, for example, Au, solder, or other metals or alloys. Au is preferred.
  • the under bump metal layer 13 is made of metal.
  • it is composed of at least one selected from the group consisting of Al, Pt, Au, Ag, Cu, Ni, Ti, Cr, Pd, and alloys mainly composed of these metals.
  • the wiring board 14 preferably has vias 22 .
  • the vias 22 are provided inside the wiring board 14 .
  • the wiring board 14 may have a plurality of external terminals 21 , in which case it is preferable that the plurality of external terminals 21 are electrically connected by vias 22 .
  • the acoustic wave element 11 on the wiring board 14 is sealed with a sealing body 23 .
  • the sealing body 23 is preferably a resin, and more preferably a resin material such as an epoxy resin, a silicone resin, a fluorine resin, or an acrylic resin mixed with an inorganic filler such as metal.
  • Embodiment 1 A modification of Embodiment 1 will be described below.
  • FIG. 4 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Modification 1 of the present invention.
  • the support substrate 16 has a cavity 20 on one main surface, the piezoelectric layer 19 is provided on the one main surface of the support substrate 16 so as to cover the cavity 20, and the functional electrode 15 is formed between the support substrate 16 and the piezoelectric layer. It is preferable that at least a part of the layer 19 overlaps with the cavity 20 when viewed from the stacking direction with the layer 19 .
  • a downward arrow in FIG. 4 represents the lamination direction of the support substrate 16 and the piezoelectric layer 19 .
  • the hollow portion 20 may be provided in a part of the support substrate 16 or may penetrate through the support substrate 16 .
  • the dielectric layer 18 may not necessarily be provided in the cavity 20 .
  • the hollow portion 20 may be provided between the support substrate 16 and the piezoelectric layer 19 .
  • the elastic wave element 11 may be an XBAR (Transversely-Excited Film Bulk Acoustic Resonator) element.
  • the functional electrode 15 has an IDT (Interdigital Transducer) electrode provided on one main surface of the piezoelectric layer 19 .
  • the cavity 20 may penetrate the dielectric layer 18 or the support substrate 16. Note that when the cavity 20 does not penetrate the dielectric layer 18 , the thickness of the dielectric layer 18 overlapping the cavity 20 out of the thickness of the dielectric layer 18 where the piezoelectric layer 19 is provided is It is preferably smaller than the thickness of the dielectric layer 18 in contact therewith.
  • FIG. 5 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Modification 2 of the present invention.
  • the acoustic wave element 11 may be an FBAR (Film Bulk Acoustic Resonator) element that utilizes bulk waves.
  • the functional electrode 15 has an upper electrode 15 a provided on one main surface of the piezoelectric layer 19 and a lower electrode 15 b provided on the other main surface of the piezoelectric layer 19 .
  • the cavity 20 may penetrate through the support substrate 16.
  • support substrate 16 may or may not have dielectric layer 18 .
  • the details of the thickness slip mode and Lamb waves are described below.
  • the functional electrodes are IDT electrodes
  • the elastic wave device in the following examples corresponds to the elastic wave element of the invention
  • the insulating layer corresponds to the dielectric layer of the invention.
  • FIG. 6 is a schematic perspective view showing the appearance of an example of an elastic wave device that utilizes bulk waves in thickness shear mode.
  • 7 is a plan view showing an electrode structure on the piezoelectric layer of the acoustic wave device shown in FIG. 6.
  • FIG. 8 is a cross-sectional view of a portion along line AA in FIG. 6.
  • the acoustic wave device 1 has a piezoelectric layer 2 made of, for example, LiNbO 3 .
  • the piezoelectric layer 2 may consist of LiTaO 3 .
  • the cut angle of LiNbO 3 or LiTaO 3 is, for example, Z-cut, but may be rotated 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 mode.
  • the piezoelectric layer 2 has a first major surface 2a and a second major surface 2b facing each other.
  • Electrodes 3 and 4 are provided on the first main surface 2 a of the piezoelectric layer 2 .
  • 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 the first busbar electrodes 5 .
  • a plurality of electrodes 4 are a plurality of second electrode fingers connected to second busbar electrodes 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 have a length direction.
  • the electrode 3 and the adjacent electrode 4 face each other in a direction perpendicular to the length direction.
  • the plurality of electrodes 3, 4, first busbar electrodes 5, and second busbar electrodes 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. That is, in FIGS. 6 and 7, the electrodes 3 and 4 may extend in the direction in which the first busbar electrode 5 and the second busbar electrode 6 extend.
  • the first busbar electrode 5 and the second busbar electrode 6 extend in the direction in which the electrodes 3 and 4 extend in FIGS.
  • 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. point to Further, when the electrodes 3 and 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 electrodes 3 and 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. Note that 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 indicates the average value of the center-to-center distances of adjacent electrodes 3 and 4 among 1.5 or more pairs of electrodes 3 and 4 .
  • 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.
  • 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. 8, 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 (see FIG. 7) 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, for example. 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, electrodes 4, first busbar electrodes 5, and second busbar electrodes 6 are made of appropriate metals or alloys such as Al and AlCu alloys.
  • the electrodes 3, 4, the first busbar electrodes 5, and the second busbar electrodes 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 electrode 5 and the second busbar electrode 6 .
  • 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. Therefore, the thickness-shear mode bulk wave is effectively excited, and good resonance characteristics can be obtained.
  • d/p is 0.24 or less, in which case even better resonance characteristics can be obtained.
  • the center-to-center distance p between adjacent electrodes 3 and 4 is the average distance between the center-to-center distances between adjacent electrodes 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. Moreover, the fact that the reflector is not required is due to the fact that the thickness shear mode bulk wave is used. The difference between the Lamb wave used in the conventional elastic wave device and the thickness shear mode bulk wave will be described with reference to FIGS. 9 and 10. FIG.
  • FIG. 9 is a schematic front cross-sectional view for explaining Lamb waves propagating through the piezoelectric film of the elastic wave device.
  • the acoustic wave device as described in Patent Document 1 (Japanese Unexamined Patent Publication No. 2012-257019)
  • 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.
  • the X direction is the direction in which the electrode fingers of the IDT electrodes are arranged.
  • the Lamb wave propagates in the X direction as shown.
  • FIG. 10 is a schematic front cross-sectional view for explaining a thickness shear mode bulk wave propagating in the piezoelectric layer of the acoustic wave device.
  • the wave connects the first main surface 2a and the second main surface 2b of the piezoelectric layer 2. It propagates substantially in the direction, ie the Z direction, and resonates. That is, the X-direction component of the wave is significantly smaller than the Z-direction component.
  • 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.
  • FIG. 11 is a diagram showing the amplitude direction of bulk waves in the thickness shear mode.
  • the amplitude direction of the thickness shear mode bulk wave is opposite between 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, as shown in FIG. FIG. 11 schematically shows a bulk wave 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.
  • the electrode 3 may be connected to the ground potential and the electrode 4 to the hot potential.
  • at least one pair of electrodes is, as described above, an electrode connected to a hot potential or an electrode connected to a ground potential, and no floating electrode is provided.
  • FIG. 12 is a diagram showing an example of resonance characteristics of the elastic wave device shown in FIG.
  • the design parameters of the elastic wave device 1 with this resonance characteristic are as follows.
  • Insulating layer 7 Silicon oxide film with a thickness of 1 ⁇ m.
  • Support member 8 Si substrate.
  • 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 equal in a plurality of pairs. That is, the electrodes 3 and 4 were arranged at equal pitches.
  • d/p is preferably 0.5 or less, More preferably, it is 0.24 or less. This will be described with reference to FIG.
  • FIG. 13 is a diagram showing the relationship between d/2p, where p is the center-to-center distance between adjacent electrodes and d is the thickness of the piezoelectric layer, and the fractional bandwidth of the acoustic wave device as a resonator.
  • 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. 14 is a plan view of another example of an elastic wave device that utilizes bulk waves in thickness-shear mode.
  • a pair of electrodes having electrodes 3 and 4 are provided on the first main surface 2 a of the piezoelectric layer 2 .
  • K in FIG. 14 is the intersection width.
  • the number of pairs of electrodes may be one. Even in this case, if d/p is 0.5 or less, bulk waves in the thickness-shear mode can be effectively excited.
  • the metallization ratio MR of the adjacent electrodes 3 and 4 satisfies MR ⁇ 1.75(d/p)+0.075. In that case, spurious can be effectively reduced. This will be described with reference to FIGS. 15 and 16.
  • FIG. 15 and 16 will be described with reference to FIGS. 15 and 16.
  • FIG. 15 is a reference diagram showing an example of resonance characteristics of the acoustic wave device shown in FIG. 6.
  • FIG. 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. In the electrode structure of FIG. 7, 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.
  • MR may be the ratio of the metallization portion included in the entire excitation region to the total area of the excitation region.
  • FIG. 16 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 elastic wave resonators are configured according to the present embodiment. is.
  • the ratio band was adjusted by changing the film thickness of the piezoelectric layer and the dimensions of the electrodes.
  • FIG. 16 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 passband appear within. That is, as in the resonance characteristics shown in FIG. 15, 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. 17 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. 17 is the area where the fractional bandwidth is 17% or less.
  • FIG. 18 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.
  • FIG. 18 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.
  • the hatched portion in FIG. 18 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° to 20°, arbitrary ⁇ ) 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) 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.
  • FIG. 19 is a partially cutaway perspective view for explaining an example of an elastic wave device using Lamb waves.
  • 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. 19, the outer periphery of the hollow portion 9 is indicated by broken lines.
  • the IDT electrode 84 includes a first busbar electrode 84a, a second busbar electrode 84b, an electrode 84c as a plurality of first electrode fingers, and an electrode 84d as a plurality of second electrode fingers. and
  • the multiple electrodes 84c are connected to the first busbar electrode 84a.
  • the multiple electrodes 84d are connected to the second busbar electrodes 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 invention may use plate waves such as Lamb waves.
  • the elastic wave device of the present invention may use bulk waves. That is, the acoustic wave device of the present invention can also be applied to bulk acoustic wave (BAW) devices.
  • the functional electrodes are the top electrode and the bottom electrode.
  • FIG. 20 is a cross-sectional view schematically showing an example of an elastic wave device using bulk waves.
  • the elastic wave device 90 has a support substrate 91 .
  • a hollow portion 93 is provided so as to penetrate through the support substrate 91 .
  • a piezoelectric layer 92 is laminated on the support substrate 91 .
  • An upper electrode 94 is provided on the first main surface 92 a of the piezoelectric layer 92
  • a lower electrode 95 is provided on the second main surface 92 b of the piezoelectric layer 92 .

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Abstract

An elastic wave device 10 comprises: an elastic wave element 11; a bump 12 electrically connected to the elastic wave element 11; an underbump metal layer 13 provided between the elastic wave element 11 and the bump 12; a wiring substrate 14 on which the elastic wave element 11 is mounted; and an encapsulant 23 covering the elastic wave element 11 on the wiring substrate 14. The elastic wave element 11 comprises: a support substrate 16 having a dielectric layer 18 on one major surface thereof; a piezoelectric layer 19 provided on the one major surface of the support substrate 16; and a functional electrode 15 provided on at least one major surface of the piezoelectric layer 19. The wiring substrate 14 is electrically connected to the elastic wave element 11 via the underbump metal layer 13 and the bump 12. In a stacking direction of the support substrate 16 and the piezoelectric layer 19, the piezoelectric layer 19 is not provided in at least a part of a gap between the bump 12 and the support substrate 16. The thickness of the dielectric layer 18 where the piezoelectric layer 19 is not provided is more than or equal to 150 nm.

Description

弾性波装置Acoustic wave device
　本発明は、弾性波装置に関する。 The present invention relates to elastic wave devices.
　従来、ニオブ酸リチウム又はタンタル酸リチウムからなる圧電層を備える弾性波装置が知られている。 Acoustic wave devices with a piezoelectric layer made of lithium niobate or lithium tantalate are conventionally known.
　特許文献１には、空洞部が形成された支持体と、上記支持体の上に上記空洞部と重なるように設けられている圧電基板と、上記圧電基板の上に上記空洞部と重なるように設けられているＩＤＴ（Ｉｎｔｅｒｄｉｇｉｔａｌ　Ｔｒａｎｓｄｕｃｅｒ）電極と、を備え、上記ＩＤＴ電極により板波が励振される弾性波装置であって、上記空洞部の端縁部は、上記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、弾性波装置が開示されている。
　特許文献２には、複数の弾性波素子が、フリップチップボンディング工法により実装基板上に実装された構成が開示されている。 Patent Document 1 discloses a support having a hollow portion, a piezoelectric substrate provided on the support so as to overlap the hollow portion, and a piezoelectric substrate on the piezoelectric substrate so as to overlap the hollow portion. and an IDT (Interdigital Transducer) electrode provided therein, wherein a Lamb wave is excited by the IDT electrode, wherein an edge portion of the hollow portion is a Lamb wave excited by the IDT electrode. An acoustic wave device is disclosed that does not include a straight portion extending parallel to the propagation direction of the .
Patent Document 2 discloses a configuration in which a plurality of acoustic wave elements are mounted on a mounting substrate by a flip chip bonding method.
特開２０１２－２５７０１９号公報JP 2012-257019 A 国際公開第２０１３／１４６３７４号WO2013/146374
　特許文献２に記載のような弾性波装置では、弾性波素子をバンプを介して実装基板に実装する際に、実装時の圧力や衝撃により、バンプ直下の圧電層が割れ、その割れが機能電極を含む励振部に至るおそれがあった。 In the acoustic wave device as described in Patent Document 2, when the acoustic wave element is mounted on the mounting substrate through the bumps, the piezoelectric layer directly under the bumps cracks due to the pressure and impact during mounting, and the cracks form the functional electrodes. There was a risk of reaching the excitation part including
　本発明は、弾性波素子の実装時に機能電極を含む励振部がダメージを受けにくい弾性波装置を提供することを目的とする。 An object of the present invention is to provide an acoustic wave device in which an excitation unit including functional electrodes is less likely to be damaged when an acoustic wave element is mounted.
　本発明の弾性波装置は、弾性波素子と、上記弾性波素子と電気的に接続されているバンプと、上記弾性波素子と上記バンプとの間に設けられたアンダーバンプメタル層と、上記弾性波素子が実装されている配線基板と、上記配線基板上で上記弾性波素子を覆っている封止体と、を備える。上記弾性波素子は、一方主面に誘電層を有する支持基板と、上記支持基板の上記一方主面に設けられた圧電層と、上記圧電層の少なくとも一方の主面に設けられた機能電極と、を備える。上記配線基板は、上記アンダーバンプメタル層及び上記バンプを介して上記弾性波素子と電気的に接続されている。上記支持基板と上記圧電層との積層方向において、上記バンプと上記支持基板との間の少なくとも一部には、圧電層が設けられておらず、上記圧電層が設けられていない部分における上記誘電層の厚みが１５０ｎｍ以上である。 An elastic wave device of the present invention includes an elastic wave element, a bump electrically connected to the elastic wave element, an under bump metal layer provided between the elastic wave element and the bump, and the elastic wave element. A wiring board on which a wave element is mounted, and a sealing body covering the acoustic wave element on the wiring board. The elastic wave element includes a support substrate having a dielectric layer on one main surface, a piezoelectric layer provided on the one main surface of the support substrate, and a functional electrode provided on at least one main surface of the piezoelectric layer. , provided. The wiring board is electrically connected to the acoustic wave element through the under bump metal layer and the bumps. In the lamination direction of the support substrate and the piezoelectric layer, at least a portion between the bump and the support substrate is not provided with the piezoelectric layer, and the dielectric layer is provided in the portion where the piezoelectric layer is not provided. The thickness of the layer is 150 nm or more.
　本発明によれば、弾性波素子の実装時に機能電極を含む励振部がダメージを受けにくい弾性波装置を提供することができる。 According to the present invention, it is possible to provide an acoustic wave device in which the excitation section including the functional electrodes is less likely to be damaged when the acoustic wave element is mounted.
図１は、本発明の実施形態１に係る弾性波装置を模式的に示す断面図である。FIG. 1 is a cross-sectional view schematically showing an elastic wave device according to Embodiment 1 of the present invention. 図２は、本発明の実施形態１に係る弾性波装置において、弾性波素子１１の一部、アンダーバンプメタル層１３及びバンプ１２を模式的に示す断面図である。FIG. 2 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Embodiment 1 of the present invention. 図３は、比較例に係る弾性波装置において、弾性波素子１１の一部、アンダーバンプメタル層１３及びバンプ１２を模式的に示す断面図である。FIG. 3 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to the comparative example. 図４は、本発明の変形例１に係る弾性波装置において、弾性波素子１１の一部、アンダーバンプメタル層１３及びバンプ１２を模式的に示す断面図である。FIG. 4 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Modification 1 of the present invention. 図５は、本発明の変形例２に係る弾性波装置において、弾性波素子１１の一部、アンダーバンプメタル層１３及びバンプ１２を模式的に示す断面図である。FIG. 5 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Modification 2 of the present invention. 図６は、厚み滑りモードのバルク波を利用する弾性波装置の一例の外観を示す略図的斜視図である。FIG. 6 is a schematic perspective view showing the appearance of an example of an acoustic wave device that utilizes a thickness shear mode bulk wave. 図７は、図６に示す弾性波装置の圧電層上の電極構造を示す平面図である。7 is a plan view showing an electrode structure on the piezoelectric layer of the acoustic wave device shown in FIG. 6. FIG. 図８は、図６中のＡ－Ａ線に沿う部分の断面図である。8 is a cross-sectional view of a portion along line AA in FIG. 6. FIG. 図９は、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。FIG. 9 is a schematic front cross-sectional view for explaining Lamb waves propagating through the piezoelectric film of the elastic wave device. 図１０は、弾性波装置の圧電層を伝播する厚み滑りモードのバルク波を説明するための模式的正面断面図である。FIG. 10 is a schematic front cross-sectional view for explaining thickness-shear mode bulk waves propagating in the piezoelectric layer of the acoustic wave device. 図１１は、厚み滑りモードのバルク波の振幅方向を示す図である。FIG. 11 is a diagram showing amplitude directions of bulk waves in the thickness shear mode. 図１２は、図６に示す弾性波装置の共振特性の一例を示す図である。12 is a diagram showing an example of resonance characteristics of the acoustic wave device shown in FIG. 6. FIG. 図１３は、隣り合う電極の中心間距離をｐ、圧電層の厚みをｄとした場合の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。FIG. 13 is a diagram showing the relationship between d/2p, where p is the center-to-center distance between adjacent electrodes and d is the thickness of the piezoelectric layer, and the fractional bandwidth of the acoustic wave device as a resonator. 図１４は、厚み滑りモードのバルク波を利用する弾性波装置の別の一例の平面図である。FIG. 14 is a plan view of another example of an elastic wave device that utilizes thickness shear mode bulk waves. 図１５は、図６に示す弾性波装置の共振特性の一例を示す参考図である。15 is a reference diagram showing an example of resonance characteristics of the acoustic wave device shown in FIG. 6. FIG. 図１６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。FIG. 16 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 elastic wave resonators are configured according to the present embodiment. is. 図１７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。FIG. 17 is a diagram showing the relationship between d/2p, metallization ratio MR, and fractional bandwidth. 図１８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。FIG. 18 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. FIG. 図１９は、ラム波を利用する弾性波装置の一例を説明するための部分切り欠き斜視図である。FIG. 19 is a partially cutaway perspective view for explaining an example of an elastic wave device using Lamb waves. 図２０は、バルク波を利用する弾性波装置の一例を模式的に示す断面図である。FIG. 20 is a cross-sectional view schematically showing an example of an elastic wave device that utilizes bulk waves.
　以下、本発明の弾性波装置について説明する。 The elastic wave device of the present invention will be described below.
　本発明の弾性波装置では、支持基板と圧電層との積層方向において、バンプと支持基板との間の少なくとも一部には、圧電層が設けられておらず、圧電層が設けられていない部分の誘電層の厚みが１５０ｎｍ以上である。バンプと支持基板との間の少なくとも一部に圧電層が設けられていないことにより、実装時の圧力や衝撃が圧電層に伝わらず、圧電層の割れを抑制することができる。
　また、バンプと支持基板との間の少なくとも一部に圧電層が設けられていない場合、アンダーバンプメタル（ＵＢＭ）層と支持基板との間に充分な絶縁が必要となるが、圧電層が設けられていない部分の誘電層の厚みが１５０ｎｍ以上であれば、充分な絶縁性も確保することができる。 In the elastic wave device of the present invention, the piezoelectric layer is not provided in at least a portion between the bump and the support substrate in the stacking direction of the support substrate and the piezoelectric layer, and the piezoelectric layer is not provided in the portion. has a dielectric layer thickness of 150 nm or more. Since the piezoelectric layer is not provided at least partly between the bumps and the support substrate, pressure and impact during mounting are not transmitted to the piezoelectric layer, and cracking of the piezoelectric layer can be suppressed.
Further, when the piezoelectric layer is not provided at least partly between the bump and the support substrate, sufficient insulation is required between the under bump metal (UBM) layer and the support substrate, but the piezoelectric layer is provided. If the thickness of the dielectric layer in the non-bonded portion is 150 nm or more, sufficient insulation can be ensured.
　本発明の弾性波装置は、第１、第２及び第３の態様において、ニオブ酸リチウム又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。 In the first, second and third aspects of the acoustic wave device of the present invention, a piezoelectric layer made of lithium niobate or lithium tantalate, a first electrode and a first electrode facing each other in a direction intersecting the thickness direction of the piezoelectric layer. 2 electrodes.
　第１の態様では、厚み滑り１次モード等の厚み滑りモードのバルク波が利用される。また、第２の態様では、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及び第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。 In the first aspect, a bulk wave in a thickness-slip mode such as a thickness-slip primary mode is used. In the second aspect, the first electrode and the second electrode are adjacent electrodes, and when 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. As a result, in the first and second modes, the Q value can be increased even when miniaturization is promoted.
　第３の態様では、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。 In the third aspect, Lamb waves are used as plate waves. Then, resonance characteristics due to the Lamb wave can be obtained.
　本発明の弾性波装置は、第４の態様において、ニオブ酸リチウム又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る。第４の態様では、バルク波が利用される。 In a fourth aspect, the acoustic wave device of the present invention 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. In a fourth aspect, bulk waves are utilized.
　以下、図面を参照しつつ、本発明の具体的な実施形態を説明することにより、本発明を明らかにする。 Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.
　以下に示す図面は模式的なものであり、その寸法、縦横比の縮尺等は実際の製品とは異なる場合がある。 The drawings shown below are schematic, and their dimensions, aspect ratio, etc. may differ from the actual product.
　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又は組み合わせが可能である。また、各実施形態を特に区別しない場合、単に「本発明の弾性波装置」という。 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. Moreover, when not distinguishing each embodiment in particular, it is only called "the elastic wave apparatus of this invention."
　図１は、本発明の実施形態１に係る弾性波装置を模式的に示す断面図である。
　図２は、本発明の実施形態１に係る弾性波装置において、弾性波素子１１の一部、アンダーバンプメタル層１３及びバンプ１２を模式的に示す断面図である。 FIG. 1 is a cross-sectional view schematically showing an elastic wave device according to Embodiment 1 of the present invention.
FIG. 2 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Embodiment 1 of the present invention.
　図１に示す弾性波装置１０は、弾性波素子１１と、弾性波素子１１と電気的に接続されているバンプ１２と、弾性波素子１１とバンプ１２との間に設けられたアンダーバンプメタル層１３と、弾性波素子１１が実装されている配線基板１４と、配線基板１４上で弾性波素子１１を覆っている封止体２３と、を備える。弾性波素子１１は、一方主面に誘電層１８を有する支持基板１６と、支持基板１６の上記一方主面に設けられた圧電層１９と、圧電層１９の一方主面に設けられた機能電極１５と、を備える。配線基板１４は、アンダーバンプメタル層１３及びバンプ１２を介して弾性波素子１１と電気的に接続されている。支持基板１６と圧電層１９との積層方向において、バンプ１２と支持基板１６との間の少なくとも一部には、圧電層１９が設けられておらず、圧電層１９が設けられていない部分における誘電層１８の厚みが１５０ｎｍ以上である。 Elastic wave device 10 shown in FIG. 13 , a wiring board 14 on which the acoustic wave element 11 is mounted, and a sealing body 23 covering the acoustic wave element 11 on the wiring board 14 . The acoustic wave element 11 includes a support substrate 16 having a dielectric layer 18 on one main surface, a piezoelectric layer 19 provided on the one main surface of the support substrate 16, and a functional electrode provided on one main surface of the piezoelectric layer 19. 15 and. The wiring board 14 is electrically connected to the acoustic wave element 11 via the under bump metal layer 13 and the bumps 12 . In the stacking direction of the support substrate 16 and the piezoelectric layer 19, the piezoelectric layer 19 is not provided at least in part between the bumps 12 and the support substrate 16, and the dielectric in the portion where the piezoelectric layer 19 is not provided is reduced. The thickness of layer 18 is 150 nm or more.
　図示されていないが、支持基板１６の一方主面には機能電極１５と電気的に接続されている配線電極が設けられている。そして、アンダーバンプメタル層１３が配線電極と電気的に接続されている。 Although not shown, wiring electrodes electrically connected to the functional electrodes 15 are provided on one main surface of the support substrate 16 . The under bump metal layer 13 is electrically connected to the wiring electrode.
　図３は、比較例に係る弾性波装置において、弾性波素子１１の一部、アンダーバンプメタル層１３及びバンプ１２を模式的に示す断面図である。 FIG. 3 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to the comparative example.
　図３に示すように、支持基板１６と圧電層１９との積層方向において、バンプ１２と支持基板１６との間の部分の全部に圧電層１９が設けられていると、弾性波素子１１をバンプ１２を介して配線基板１４に実装する際に、実装時の圧力や衝撃により、バンプ１２直下の圧電層１９が割れ、その割れが機能電極１５を含む励振部に至るおそれがある。 As shown in FIG. 3, if the piezoelectric layer 19 is provided entirely between the bumps 12 and the supporting substrate 16 in the stacking direction of the supporting substrate 16 and the piezoelectric layer 19, the elastic wave element 11 can be bumped. When the piezoelectric layer 19 is mounted on the wiring board 14 via the bumps 12 , the piezoelectric layer 19 directly under the bumps 12 may crack due to pressure or impact during mounting, and the cracks may reach the excitation section including the functional electrodes 15 .
　これに対し、図２に示すように、支持基板１６と圧電層１９との積層方向において、バンプ１２と支持基板１６との間の少なくとも一部に、圧電層１９が設けられていないことより、実装時の圧力や衝撃が圧電層１９に伝わらず、圧電層１９の割れを抑制することができる。
　図２における下向きの矢印は、支持基板１６と圧電層１９との積層方向を表す。 On the other hand, as shown in FIG. 2, the piezoelectric layer 19 is not provided at least partly between the bumps 12 and the support substrate 16 in the stacking direction of the support substrate 16 and the piezoelectric layer 19. Pressure and impact during mounting are not transmitted to the piezoelectric layer 19, and cracking of the piezoelectric layer 19 can be suppressed.
A downward arrow in FIG. 2 represents the lamination direction of the support substrate 16 and the piezoelectric layer 19 .
圧電層１９が設けられていない部分における誘電層１８の厚みは１５０ｎｍ以上である。図２中、圧電層１９が設けられていない部分における誘電層１８の厚みをＴ１で示す。当該部分における誘電層１８の厚みとしては、１５０ｎｍ以上、５，０００ｎｍ以下であることが好ましい。より好ましくは１，０００ｎｍ以上、３，０００ｎｍ以下である。 The thickness of the dielectric layer 18 in the portion where the piezoelectric layer 19 is not provided is 150 nm or more. In FIG. 2, T1 indicates the thickness of the dielectric layer 18 where the piezoelectric layer 19 is not provided. It is preferable that the thickness of the dielectric layer 18 in this portion is 150 nm or more and 5,000 nm or less. It is more preferably 1,000 nm or more and 3,000 nm or less.
　誘電層１８は、圧電層１９が設けられている部分と圧電層１９が設けられていない部分とで同一の材料からなることが好ましい。これにより、低コストで簡易かつ高精度で一括形成することができる。 It is preferable that the dielectric layer 18 is made of the same material in the portion where the piezoelectric layer 19 is provided and the portion where the piezoelectric layer 19 is not provided. As a result, it is possible to collectively form them at low cost, simply and with high accuracy.
　圧電層１９が設けられている部分の誘電層１８の最大厚みは、圧電層１９の最大厚みの２倍以上であることが好ましい。この場合、誘電層１８上に設けた圧電層１９をＡｒイオン等で除去して圧電層１９が設けられていない部分を形成する際に、オーバーエッチング後も充分な絶縁性を確保することができ、また、エッチング時間の管理が容易になる。図２中、圧電層１９が設けられている部分の誘電層１８の厚みをＴ２で示し、圧電層１９の厚みをｔで示す。
　圧電層１９が設けられていない部分の誘電層１８の最大厚みは、圧電層１９が設けられている部分の誘電層１８の最大厚みと同じでもよく、圧電層１９が設けられている部分の誘電層１８の最大厚みより小さくてもよい。 The maximum thickness of the dielectric layer 18 at the portion where the piezoelectric layer 19 is provided is preferably at least twice the maximum thickness of the piezoelectric layer 19 . In this case, when the piezoelectric layer 19 provided on the dielectric layer 18 is removed with Ar ions or the like to form a portion where the piezoelectric layer 19 is not provided, sufficient insulation can be secured even after overetching. , and the etching time can be easily managed. In FIG. 2, the thickness of the dielectric layer 18 where the piezoelectric layer 19 is provided is indicated by T2 , and the thickness of the piezoelectric layer 19 is indicated by t.
The maximum thickness of the dielectric layer 18 in the portion where the piezoelectric layer 19 is not provided may be the same as the maximum thickness of the dielectric layer 18 in the portion where the piezoelectric layer 19 is provided. It may be less than the maximum thickness of layer 18 .
　圧電層１９が設けられていない部分の形状、大きさは特に限定されない。バンプ１２と支持基板１６との間に圧電層１９が設けられていない部分は１箇所のみ存在してもよく、２箇所以上存在してもよい。 The shape and size of the portion where the piezoelectric layer 19 is not provided are not particularly limited. The portion where the piezoelectric layer 19 is not provided between the bump 12 and the support substrate 16 may exist at only one location, or may exist at two or more locations.
　圧電層１９が設けられていない部分は、支持基板１６と圧電層１９との積層方向において、バンプ１２と支持基板１６との間にあればよいが、機能電極１５とバンプ１２の中心とを結ぶ直線上に位置することが好ましい。この場合、圧電層１９の割れをより効果的に抑制することができる。 The portion where the piezoelectric layer 19 is not provided may be between the bump 12 and the support substrate 16 in the stacking direction of the support substrate 16 and the piezoelectric layer 19, but the functional electrode 15 and the center of the bump 12 are connected. A straight line is preferred. In this case, cracking of the piezoelectric layer 19 can be more effectively suppressed.
　少なくともバンプ１２の中心部には、圧電層１９が設けられていないことが好ましい。圧電層１９が設けられていない領域は、バンプ１２とアンダーバンプメタル層１３とが接する領域以上であることがより好ましく、アンダーバンプメタル層１３が設けられている領域以上であることが更に好ましい。これにより、圧電層１９の割れをより充分に抑制することができる。
　アンダーバンプメタル層１３と支持基板１６との間の部分の全部に圧電層１９が設けられていない形態は、本発明の好ましい実施形態の１つである。 It is preferable that the piezoelectric layer 19 is not provided at least at the central portion of the bump 12 . The area where the piezoelectric layer 19 is not provided is more preferably equal to or larger than the area where the bump 12 and the under bump metal layer 13 are in contact, and more preferably equal to or larger than the area where the under bump metal layer 13 is provided. Thereby, cracking of the piezoelectric layer 19 can be suppressed more sufficiently.
A configuration in which the piezoelectric layer 19 is not provided entirely between the under bump metal layer 13 and the support substrate 16 is one of the preferred embodiments of the present invention.
　誘電層１８は、例えば、酸化ケイ素（ＳｉＯｘ）からなる。その場合、誘電層１８は、ＳｉＯ２から構成されることが好ましい。これにより、周波数温度特性をより向上させることができる。
　誘電層１８の材料は上記に限定されず、例えば、窒化ケイ素（ＳｉｘＮｙ）などを用いることもできる。その場合、誘電層１８は、Ｓｉ３Ｎ４から構成されてもよい。 The dielectric layer 18 is made of silicon oxide (SiO x ), for example. In that case, dielectric layer 18 is preferably composed of SiO 2 . Thereby, the frequency temperature characteristic can be further improved.
The material of the dielectric layer 18 is not limited to the above, and for example, silicon nitride (Si x N y ) can also be used. In that case, dielectric layer 18 may consist of Si 3 N 4 .
　圧電層１９は、例えば、ニオブ酸リチウム（ＬｉＮｂＯｘ）又はタンタル酸リチウム（ＬｉＴａＯｘ）からなる。その場合、圧電層１９は、ＬｉＮｂＯ３又はＬｉＴａＯ３から構成されてもよい。
　また、圧電層１９は、圧電体の単結晶からなることが好ましい。圧電体の単結晶は多結晶と比べて実装時に割れやすいため、本発明の技術的意義がより充分に発揮される。
　上記圧電体の単結晶は、ＸＲＤ（Ｘ－ｒａｙ　Ｄｉｆｆｒａｃｔｏｍｅｔｅｒ）により分析することができる。
　ＸＲＤとは、試料にＸ線を照射し、試料から出る回折Ｘ線を測定することで試料の結晶構造を評価する装置である。結晶構造を評価できることから、同じ化学式の多形、例えばクオーツ、トリジマイト、クリストバライト、シリカガラス（化学式はすべてＳｉＯ２）を区別することができる。また、得られたピークの位置や幅を評価することで格子定数や結晶性を評価することもできる。 The piezoelectric layer 19 is made of lithium niobate (LiNbO x ) or lithium tantalate (LiTaO x ), for example. In that case, the piezoelectric layer 19 may consist of LiNbO 3 or LiTaO 3 .
Moreover, the piezoelectric layer 19 is preferably made of a piezoelectric single crystal. Since the single crystal of the piezoelectric material is more susceptible to cracking during mounting than the polycrystal, the technical significance of the present invention is more fully exhibited.
The single crystal of the piezoelectric material can be analyzed by XRD (X-ray Diffractometer).
XRD is an apparatus that evaluates the crystal structure of a sample by irradiating the sample with X-rays and measuring the diffracted X-rays emitted from the sample. The ability to assess the crystal structure allows one to distinguish between polymorphs of the same chemical formula, such as quartz, tridymite, cristobalite, silica glass (all chemical formulas are SiO 2 ). Also, the lattice constant and crystallinity can be evaluated by evaluating the position and width of the obtained peak.
　圧電層１９が圧電体の単結晶からなる場合、機能電極１５とバンプ１２とを結ぶ直線が、圧電層１９の結晶へき開方向(へき開面に平行な方向)と平行であることが好ましい。結晶へき開面で割れが進行するため、これにより、割れの進行をより効率的に止めることができる。 When the piezoelectric layer 19 is made of a piezoelectric single crystal, the straight line connecting the functional electrode 15 and the bump 12 is preferably parallel to the crystal cleavage direction (direction parallel to the cleavage plane) of the piezoelectric layer 19 . Since cracking progresses on the crystal cleavage plane, this makes it possible to stop the progress of cracking more efficiently.
　支持基板１６は空洞部を有していてもよく、空洞部を有していなくてもよい。 The support substrate 16 may or may not have a cavity.
支持基板１６は、一方主面に誘電層１８を有するものであればよいが、支持部材１７と、支持部材１７と圧電層１９との間に設けられた誘電層１８とを含むものであることが好ましい。 The support substrate 16 may have a dielectric layer 18 on one main surface, but preferably includes a support member 17 and a dielectric layer 18 provided between the support member 17 and the piezoelectric layer 19 . .
　支持部材１７は、例えば、シリコン（Ｓｉ）からなる。支持部材１７の材料は上記に限定されず、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、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または樹脂などを用いることもできる。 The support member 17 is made of silicon (Si), for example. The material of the support member 17 is not limited to the above, and examples thereof include aluminum oxide, lithium tantalate, lithium niobate, piezoelectric materials such as crystal, alumina, sapphire, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, and mullite. , various ceramics such as steatite and forsterite, dielectrics such as diamond and glass, semiconductors such as gallium nitride, and resins.
　配線基板１４は、アンダーバンプメタル層１３及びバンプ１２を介して弾性波素子１１と電気的に接続されている。配線基板１４は、一例として、プリント配線基板により構成されている。プリント配線基板の線膨張係数は、例えば、１５ｐｐｍ／℃程度である。プリント配線基板は、ガラス布・エポキシ樹脂銅張積層板から形成されている。
　より詳細には、弾性波素子１１の圧電層１９は、その主面が配線基板１４と対向して配置される。弾性波素子１１は、バンプ１２を介して配線基板１４の外部端子２１にそれぞれ実装される。
　これにより、圧電層１９の一方主面と配線基板１４との間に空間が形成される。機能電極１５は、圧電層１９の一方主面と配線基板１４との間に設けられる。
　より詳細には、弾性波素子１１は、配線基板１４の上に、外部端子２１、バンプ１２、アンダーバンプメタル層１３、圧電層１９、支持基板１６の順に積層される。 The wiring board 14 is electrically connected to the acoustic wave element 11 via the under bump metal layer 13 and the bumps 12 . The wiring board 14 is configured by, for example, a printed wiring board. The coefficient of linear expansion of the printed wiring board is, for example, about 15 ppm/°C. The printed wiring board is formed of a glass cloth/epoxy resin copper-clad laminate.
More specifically, the piezoelectric layer 19 of the acoustic wave element 11 is arranged with its main surface facing the wiring board 14 . The acoustic wave elements 11 are mounted on the external terminals 21 of the wiring board 14 via the bumps 12 .
Thereby, a space is formed between the one main surface of the piezoelectric layer 19 and the wiring substrate 14 . The functional electrode 15 is provided between one main surface of the piezoelectric layer 19 and the wiring board 14 .
More specifically, the elastic wave element 11 is laminated on the wiring substrate 14 in the order of the external terminals 21, the bumps 12, the under bump metal layer 13, the piezoelectric layer 19, and the support substrate 16. FIG.
　バンプ１２は、例えば、Ａｕ、はんだ等の金属又は合金により形成することができる。好ましくはＡｕである。 The bumps 12 can be made of, for example, Au, solder, or other metals or alloys. Au is preferred.
　アンダーバンプメタル層１３は、金属から構成される。例えば、Ａｌ、Ｐｔ、Ａｕ、Ａｇ、Ｃｕ、Ｎｉ、Ｔｉ、Ｃｒ、Ｐｄ及びこれらの金属を主体とする合金からなる群から選択される少なくとも１種から構成される。 The under bump metal layer 13 is made of metal. For example, it is composed of at least one selected from the group consisting of Al, Pt, Au, Ag, Cu, Ni, Ti, Cr, Pd, and alloys mainly composed of these metals.
　配線基板１４は、ビア２２を有することが好ましい。ビア２２は、配線基板１４の内部に設けられる。配線基板１４は、複数の外部端子２１を有していてもよく、その場合、ビア２２により複数の外部端子２１が電気的に接続されることが好ましい。　 The wiring board 14 preferably has vias 22 . The vias 22 are provided inside the wiring board 14 . The wiring board 14 may have a plurality of external terminals 21 , in which case it is preferable that the plurality of external terminals 21 are electrically connected by vias 22 .　
　配線基板１４上の弾性波素子１１は、封止体２３によって封止されている。封止体２３として好ましくは樹脂であり、より好ましくは、エポキシ系樹脂、シリコーン系樹脂、フッ素系樹脂、またはアクリル系樹脂などの樹脂材料に金属等の無機フィラーを混入させた材料等である。 The acoustic wave element 11 on the wiring board 14 is sealed with a sealing body 23 . The sealing body 23 is preferably a resin, and more preferably a resin material such as an epoxy resin, a silicone resin, a fluorine resin, or an acrylic resin mixed with an inorganic filler such as metal.
　以下、実施形態１の変形例について説明する。 A modification of Embodiment 1 will be described below.
　図４は、本発明の変形例１に係る弾性波装置において、弾性波素子１１の一部、アンダーバンプメタル層１３及びバンプ１２を模式的に示す断面図である。 FIG. 4 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Modification 1 of the present invention.
　支持基板１６は、一方主面に空洞部２０を有し、圧電層１９は、空洞部２０を覆うように支持基板１６の上記一方主面に設けられ、機能電極１５は、支持基板１６と圧電層１９との積層方向から見て、少なくとも一部が空洞部２０と重なるように設けられていることが好ましい。
　図４における下向きの矢印は、支持基板１６と圧電層１９との積層方向を表す。 The support substrate 16 has a cavity 20 on one main surface, the piezoelectric layer 19 is provided on the one main surface of the support substrate 16 so as to cover the cavity 20, and the functional electrode 15 is formed between the support substrate 16 and the piezoelectric layer. It is preferable that at least a part of the layer 19 overlaps with the cavity 20 when viewed from the stacking direction with the layer 19 .
A downward arrow in FIG. 4 represents the lamination direction of the support substrate 16 and the piezoelectric layer 19 .
　空洞部２０は、支持基板１６の一部に設けられていてもよく、支持基板１６を貫通してもよい。なお、空洞部２０において誘電層１８は必ずしも設けられていなくてもよい。すなわち、空洞部２０は、支持基板１６と圧電層１９との間に設けられていればよい。 The hollow portion 20 may be provided in a part of the support substrate 16 or may penetrate through the support substrate 16 . Note that the dielectric layer 18 may not necessarily be provided in the cavity 20 . In other words, the hollow portion 20 may be provided between the support substrate 16 and the piezoelectric layer 19 .
　例えば、弾性波素子１１は、ＸＢＡＲ（Ｔｒａｎｓｖｅｒｓｅｌｙ－Ｅｘｃｉｔｅｄ　Ｆｉｌｍ　Ｂｕｌｋ　Ａｃｏｕｓｔｉｃ　Ｒｅｓｏｎａｔｏｒ）素子であってもよい。その場合、機能電極１５は、圧電層１９の一方の主面に設けられたＩＤＴ（Ｉｎｔｅｒｄｉｇｉｔａｌ　Ｔｒａｎｓｄｕｃｅｒ）電極を有する。 For example, the elastic wave element 11 may be an XBAR (Transversely-Excited Film Bulk Acoustic Resonator) element. In that case, the functional electrode 15 has an IDT (Interdigital Transducer) electrode provided on one main surface of the piezoelectric layer 19 .
　空洞部２０は、誘電層１８又は支持基板１６を貫通してもよい。なお、空洞部２０が誘電層１８を貫通しない場合、圧電層１９が設けられている部分の誘電層１８の厚みのうち、空洞部２０と重なる部分の誘電層１８の厚みは、圧電層１９に接する部分の誘電層１８の厚みよりも小さいことが好ましい。 The cavity 20 may penetrate the dielectric layer 18 or the support substrate 16. Note that when the cavity 20 does not penetrate the dielectric layer 18 , the thickness of the dielectric layer 18 overlapping the cavity 20 out of the thickness of the dielectric layer 18 where the piezoelectric layer 19 is provided is It is preferably smaller than the thickness of the dielectric layer 18 in contact therewith.
　図５は、本発明の変形例２に係る弾性波装置において、弾性波素子１１の一部、アンダーバンプメタル層１３及びバンプ１２を模式的に示す断面図である。 FIG. 5 is a cross-sectional view schematically showing part of the acoustic wave element 11, the under bump metal layer 13 and the bumps 12 in the acoustic wave device according to Modification 2 of the present invention.
　図５に示すとおり、弾性波素子１１は、バルク波を利用するＦＢＡＲ（Ｆｉｌｍ　Ｂｕｌｋ　Ａｃｏｕｓｔｉｃ　Ｒｅｓｏｎａｔｏｒ）素子であってもよい。その場合、機能電極１５は、圧電層１９の一方の主面に設けられた上部電極１５ａと、圧電層１９の他方の主面に設けられた下部電極１５ｂとを有する。 As shown in FIG. 5, the acoustic wave element 11 may be an FBAR (Film Bulk Acoustic Resonator) element that utilizes bulk waves. In that case, the functional electrode 15 has an upper electrode 15 a provided on one main surface of the piezoelectric layer 19 and a lower electrode 15 b provided on the other main surface of the piezoelectric layer 19 .
　図５に示すとおり、空洞部２０は、支持基板１６を貫通してもよい。その場合、支持基板１６は誘電層１８を有してもよく、誘電層１８を有しなくてもよい。 As shown in FIG. 5, the cavity 20 may penetrate through the support substrate 16. In that case, support substrate 16 may or may not have dielectric layer 18 .
　以下において、厚み滑りモード及び板波の詳細を説明する。なお、以下においては、機能電極がＩＤＴ電極である場合の例を用いて説明する。以下の例における弾性波装置は本発明における弾性波素子に相当し、絶縁層は本発明における誘電層に相当する。 The details of the thickness slip mode and Lamb waves are described below. In the following description, an example in which the functional electrodes are IDT electrodes will be described. The elastic wave device in the following examples corresponds to the elastic wave element of the invention, and the insulating layer corresponds to the dielectric layer of the invention.
　図６は、厚み滑りモードのバルク波を利用する弾性波装置の一例の外観を示す略図的斜視図である。図７は、図６に示す弾性波装置の圧電層上の電極構造を示す平面図である。図８は、図６中のＡ－Ａ線に沿う部分の断面図である。 FIG. 6 is a schematic perspective view showing the appearance of an example of an elastic wave device that utilizes bulk waves in thickness shear mode. 7 is a plan view showing an electrode structure on the piezoelectric layer of the acoustic wave device shown in FIG. 6. FIG. 8 is a cross-sectional view of a portion along line AA in FIG. 6. FIG.
　弾性波装置１は、例えば、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又はＬｉＴａＯ３のカット角は、例えばＺカットであるが、回転Ｙカット又は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、厚み滑りモードを効果的に励振するには、５０ｎｍ以上、１０００ｎｍ以下であることが好ましい。圧電層２は、対向し合う第１の主面２ａ及び第２の主面２ｂを有する。圧電層２の第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６及び図７では、複数の電極３が、第１のバスバー電極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のバスバー電極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。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、電極４、第１のバスバー電極５及び第２のバスバー電極６によりＩＤＴ（Ｉｎｔｅｒｄｉｇｉｔａｌ　Ｔｒａｎｓｄｕｃｅｒ）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。また、電極３，４の長さ方向が図６及び図７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６及び図７において、第１のバスバー電極５及び第２のバスバー電極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のバスバー電極５及び第２のバスバー電極６は、図６及び図７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。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。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、ホット電極又は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対又は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。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た場合に、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。 The acoustic wave device 1 has a piezoelectric layer 2 made of, for example, LiNbO 3 . The piezoelectric layer 2 may consist of LiTaO 3 . The cut angle of LiNbO 3 or LiTaO 3 is, for example, Z-cut, but may be rotated 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 mode. The piezoelectric layer 2 has a first major surface 2a and a second major surface 2b facing each other. Electrodes 3 and 4 are provided on the first main surface 2 a of the piezoelectric layer 2 . Here, the electrode 3 is an example of the "first electrode" and the electrode 4 is an example of the "second electrode". In FIGS. 6 and 7 , the multiple electrodes 3 are multiple first electrode fingers connected to the first busbar electrodes 5 . A plurality of electrodes 4 are a plurality of second electrode fingers connected to second busbar electrodes 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 have a length direction. The electrode 3 and the adjacent electrode 4 face each other in a direction perpendicular to the length direction. The plurality of electrodes 3, 4, first busbar electrodes 5, and second busbar electrodes 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 . Moreover, 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. That is, in FIGS. 6 and 7, the electrodes 3 and 4 may extend in the direction in which the first busbar electrode 5 and the second busbar electrode 6 extend. In that case, the first busbar electrode 5 and the second busbar electrode 6 extend in the direction in which the electrodes 3 and 4 extend in FIGS. 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 Further, when the electrodes 3 and 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 electrodes 3 and 4. FIG. 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. Note that 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 used as a pair of electrode sets, and when there are 1.5 or more pairs of electrodes), the center-to-center distance between the electrodes 3 and 4 is indicates the average value of the center-to-center distances of adjacent electrodes 3 and 4 among 1.5 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.
　本実施形態において、Ｚカットの圧電層を用いる場合、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 this embodiment, when a Z-cut piezoelectric layer is used, 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８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（図７参照）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. 8, 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 (see FIG. 7) 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、例えば、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, for example. 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、電極４、第１のバスバー電極５及び第２のバスバー電極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、電極４、第１のバスバー電極５及び第２のバスバー電極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, electrodes 4, first busbar electrodes 5, and second busbar electrodes 6 are made of appropriate metals or alloys such as Al and AlCu alloys. In this embodiment, the electrodes 3, 4, the first busbar electrodes 5, and the second busbar electrodes 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のバスバー電極５と第２のバスバー電極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。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。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対の電極組とした場合に電極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。 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 electrode 5 and the second busbar electrode 6 . As a result, it is possible to obtain resonance characteristics using bulk waves in the thickness-shear mode excited in the piezoelectric layer 2 . 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. Therefore, the thickness-shear 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. When at least one of the electrodes 3 and 4 is plural as in the present embodiment, that is, when the electrodes 3 and 4 form one pair of electrodes and the number of the electrodes 3 and 4 is 1.5 or more, The center-to-center distance p between adjacent electrodes 3 and 4 is the average distance between the center-to-center distances between adjacent electrodes 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、厚み滑りモードのバルク波を利用していることによる。従来の弾性波装置で利用したラム波と、上記厚み滑りモードのバルク波の相違を、図９及び図１０を参照して説明する。 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. Moreover, the fact that the reflector is not required is due to the fact that the thickness shear mode bulk wave is used. The difference between the Lamb wave used in the conventional elastic wave device and the thickness shear mode bulk wave will be described with reference to FIGS. 9 and 10. FIG.
　図９は、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。図９に示すように、特許文献１（日本公開特許公報　特開２０１２－２５７０１９号公報）に記載のような弾性波装置では、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９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. 9 is a schematic front cross-sectional view for explaining Lamb waves propagating through the piezoelectric film of the elastic wave device. As shown in FIG. 9, in the acoustic wave device as described in Patent Document 1 (Japanese Unexamined Patent Publication No. 2012-257019), 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. 9, the Lamb 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１０は、弾性波装置の圧電層を伝播する厚み滑りモードのバルク波を説明するための模式的正面断面図である。図１０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, FIG. 10 is a schematic front cross-sectional view for explaining a thickness shear mode bulk wave propagating in the piezoelectric layer of the acoustic wave device. As shown in FIG. 10, in the elastic wave device 1 of the present embodiment, since the vibration displacement is in the thickness slip direction, the wave connects the first main surface 2a and the second main surface 2b of the piezoelectric layer 2. It propagates substantially in the direction, ie 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.
　図１１は、厚み滑りモードのバルク波の振幅方向を示す図である。厚み滑りモードのバルク波の振幅方向は、図１１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１１では、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ある。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。 FIG. 11 is a diagram showing the amplitude direction of bulk waves in the thickness shear mode. The amplitude direction of the thickness shear mode bulk wave is opposite between 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, as shown in FIG. FIG. 11 schematically shows a bulk wave 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, the electrode 3 may be connected to the ground potential and the electrode 4 to the hot potential. In this embodiment, at least one pair of electrodes is, as described above, an electrode connected to a hot potential or an electrode connected to a ground potential, and no floating electrode is provided.
　図１２は、図６に示す弾性波装置の共振特性の一例を示す図である。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。 FIG. 12 is a diagram showing an example of resonance characteristics of the elastic wave device shown in FIG. The design parameters of the elastic wave device 1 with this resonance characteristic are as follows.
　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基板。 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 substrate.
　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.
　弾性波装置１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 the elastic wave device 1, the inter-electrode distances of the electrode pairs consisting of the electrodes 3 and 4 are all equal in a plurality of pairs. That is, the electrodes 3 and 4 were arranged at equal pitches.
　図１２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. 12, good resonance characteristics with a specific bandwidth of 12.5% are obtained despite the absence of reflectors.
　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、好ましくは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１３を参照して説明する。 By the way, assuming that 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 preferably 0.5 or less, More preferably, it is 0.24 or less. This will be described with reference to FIG.
　図１２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１３は、隣り合う電極の中心間距離をｐ、圧電層の厚みをｄとした場合の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. 13 is a diagram showing the relationship between d/2p, where p is the center-to-center distance between adjacent electrodes and d is the thickness of the piezoelectric layer, and the fractional bandwidth of the acoustic wave device as a resonator.
　図１３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、ｄ／ｐを０．５以下とすることにより、上記厚み滑り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. 13, 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, by setting d/p to 0.5 or less, it is possible to construct a resonator having a high coupling coefficient using the thickness-shear mode bulk wave.
　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については、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。 As 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１４は、厚み滑りモードのバルク波を利用する弾性波装置の別の一例の平面図である。 FIG. 14 is a plan view of another example of an elastic wave device that utilizes bulk waves in thickness-shear mode.
　弾性波装置６１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１４中のＫが交差幅となる。前述したように、本実施形態の弾性波装置では、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、厚み滑りモードのバルク波を効果的に励振することができる。 In the elastic wave device 61 , a pair of electrodes having electrodes 3 and 4 are provided on the first main surface 2 a of the piezoelectric layer 2 . Note that K in FIG. 14 is the intersection width. As described above, in the elastic wave device of this embodiment, the number of pairs of electrodes may be one. Even in this case, if d/p is 0.5 or less, bulk waves in the thickness-shear mode can be effectively excited.
　本実施形態の弾性波装置では、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。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。これを、図１５及び図１６を参照して説明する。 In the acoustic wave device of the present embodiment, preferably, in the plurality of electrodes 3 and 4, for the excitation region, which is the region where any of the adjacent electrodes 3 and 4 overlap when viewed in the facing direction, It is desirable that the metallization ratio MR of the adjacent electrodes 3 and 4 satisfies MR≦1.75(d/p)+0.075. In that case, spurious can be effectively reduced. This will be described with reference to FIGS. 15 and 16. FIG.
　図１５は、図６に示す弾性波装置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。 15 is a reference diagram showing an example of resonance characteristics of the acoustic wave device shown in FIG. 6. 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７を参照して説明する。図７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. In the electrode structure of FIG. 7, 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１６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１６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. 16 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 elastic wave resonators are configured according to the present embodiment. is. The ratio band was adjusted by changing the film thickness of the piezoelectric layer and the dimensions of the electrodes. Also, FIG. 16 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１６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１６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１５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. 16, the spurious is as large as 1.0. As is clear from FIG. 16, when the fractional band exceeds 0.17, that is, when it exceeds 17%, even if a large spurious with a spurious level of 1 or more changes the parameters constituting the fractional band, the passband appear within. That is, as in the resonance characteristics shown in FIG. 15, 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１７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。 FIG. 17 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.
　図１７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１７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。 The hatched portion on the right side of the dashed line D in FIG. 17 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１８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。 FIG. 18 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. FIG.
　図１８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。
　（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）
　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るため好ましい。 The hatched portion in FIG. 18 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° 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)
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１９は、ラム波を利用する弾性波装置の一例を説明するための部分切り欠き斜視図である。 FIG. 19 is a partially cutaway perspective view for explaining an example of an elastic wave device using Lamb waves.
　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１９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のバスバー電極８４ａと、第２のバスバー電極８４ｂと、複数本の第１の電極指としての電極８４ｃと、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のバスバー電極８４ａに接続されている。複数本の電極８４ｄは、第２のバスバー電極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。 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. 19, the outer periphery of the hollow portion 9 is indicated by broken lines. Here, the IDT electrode 84 includes a first busbar electrode 84a, a second busbar electrode 84b, an electrode 84c as a plurality of first electrode fingers, and an electrode 84d as a plurality of second electrode fingers. and The multiple electrodes 84c are connected to the first busbar electrode 84a. The multiple electrodes 84d are connected to the second busbar electrodes 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、本発明の弾性波装置は、ラム波等の板波を利用するものであってもよい。 Thus, the elastic wave device of the present invention may use plate waves such as Lamb waves.
　また、本発明の弾性波装置は、バルク波を利用するものであってもよい。すなわち、本発明の弾性波装置は、バルク弾性波（ＢＡＷ）素子にも適用できる。この場合、機能電極は、上部電極及び下部電極である。 Also, the elastic wave device of the present invention may use bulk waves. That is, the acoustic wave device of the present invention can also be applied to bulk acoustic wave (BAW) devices. In this case, the functional electrodes are the top electrode and the bottom electrode.
　図２０は、バルク波を利用する弾性波装置の一例を模式的に示す断面図である。 FIG. 20 is a cross-sectional view schematically showing an example of an elastic wave device using bulk waves.
　弾性波装置９０は、支持基板９１を備える。支持基板９１を貫通するように空洞部９３が設けられている。支持基板９１上に圧電層９２が積層されている。圧電層９２の第１の主面９２ａには上部電極９４が設けられ、圧電層９２の第２の主面９２ｂには下部電極９５が設けられている。 The elastic wave device 90 has a support substrate 91 . A hollow portion 93 is provided so as to penetrate through the support substrate 91 . A piezoelectric layer 92 is laminated on the support substrate 91 . An upper electrode 94 is provided on the first main surface 92 a of the piezoelectric layer 92 , and a lower electrode 95 is provided on the second main surface 92 b of the piezoelectric layer 92 .
　１　弾性波装置
　２　圧電層
　２ａ　圧電層の第１の主面
　２ｂ　圧電層の第２の主面
　３　第１電極
　４　第２電極
　５　第１のバスバー電極
　６　第２のバスバー電極
　７　絶縁層
　７ａ　開口部
　８　支持部材
　８ａ　開口部
　９　空洞部
　１０　弾性波装置
　１１　弾性波素子
　１２　バンプ
　１３　アンダーバンプメタル層
　１４　配線基板
　１５　機能電極
　１５ａ　上部電極
　１５ｂ　下部電極
　１６　支持基板
　１７　支持部材
　１８　誘電層
　１９　圧電層
　２０　空洞部
　２１　外部端子
　２２　ビア
　２３　封止体
　６１　弾性波装置
　８１　弾性波装置
　８２　支持基板
　８３　圧電層
　８４ａ　第１のバスバー電極
　８４ｂ　第２のバスバー電極
　８４ｃ　第１電極（第１電極指）
　８４ｄ　第２電極（第２電極指）
　８５、８６　反射器
　９０　弾性波装置
　９１　支持基板
　９２　圧電層
　９２ａ　圧電層の第１の主面
　９２ｂ　圧電層の第２の主面
　９３　空洞部
　９４　上部電極
　９５　下部電極
　２０１　圧電膜
　２０１ａ　圧電膜の第１の主面
　２０１ｂ　圧電膜の第２の主面
　４５１　第１領域
　４５２　第２領域
　Ｃ　励振領域
　ＶＰ１　仮想平面
　Ｔ１　圧電層１９が設けられていない部分における誘電層１８の厚み
　Ｔ２　圧電層１９が設けられている部分の誘電層１８の厚み
　ｔ　圧電層１９の厚み REFERENCE SIGNS LIST 1 elastic wave device 2 piezoelectric layer 2a first main surface of piezoelectric layer 2b second main surface of piezoelectric layer 3 first electrode 4 second electrode 5 first busbar electrode 6 second busbar electrode 7 insulating layer 7a opening Part 8 Supporting member 8a Opening 9 Cavity 10 Elastic wave device 11 Elastic wave element 12 Bump 13 Under bump metal layer 14 Wiring substrate 15 Functional electrode 15a Upper electrode 15b Lower electrode 16 Supporting substrate 17 Supporting member 18 Dielectric layer 19 Piezoelectric layer 20 Cavity 21 External terminal 22 Via 23 Sealing body 61 Elastic wave device 81 Elastic wave device 82 Support substrate 83 Piezoelectric layer 84a First busbar electrode 84b Second busbar electrode 84c First electrode (first electrode finger)
84d second electrode (second electrode finger)
85, 86 reflector 90 elastic wave device 91 support substrate 92 piezoelectric layer 92a first main surface of piezoelectric layer 92b second main surface of piezoelectric layer 93 cavity 94 upper electrode 95 lower electrode 201 piezoelectric film 201a second main surface of piezoelectric film 1 principal surface 201b second principal surface of piezoelectric film 451 first region 452 second region C excitation region VP1 imaginary plane T 1 thickness of dielectric layer 18 at portion where piezoelectric layer 19 is not provided T 2 piezoelectric layer 19 Thickness of the dielectric layer 18 where it is provided t Thickness of the piezoelectric layer 19

Claims (16)

  1. 　弾性波素子と、
    　前記弾性波素子と電気的に接続されているバンプと、
    前記弾性波素子と前記バンプとの間に設けられたアンダーバンプメタル層と、
    　前記弾性波素子が実装されている配線基板と、
    　前記配線基板上で前記弾性波素子を覆っている封止体と、
    を備え、
    　前記弾性波素子は、
    　　一方主面に誘電層を有する支持基板と、
    　　前記支持基板の前記一方主面に設けられた圧電層と、
    　　前記圧電層の少なくとも一方の主面に設けられた機能電極と、
    を備え、
    　前記配線基板は、前記アンダーバンプメタル層及び前記バンプを介して前記弾性波素子と電気的に接続され、
    前記支持基板と前記圧電層との積層方向において、前記バンプと前記支持基板との間の少なくとも一部には、圧電層が設けられておらず、
    　前記圧電層が設けられていない部分における前記誘電層の厚みが１５０ｎｍ以上である
    　弾性波装置。     an acoustic wave element;
    a bump electrically connected to the acoustic wave element;
    an under bump metal layer provided between the acoustic wave element and the bump;
    a wiring board on which the acoustic wave element is mounted;
    a sealing body covering the acoustic wave element on the wiring board;
    with
    The elastic wave element is
    a support substrate having a dielectric layer on one main surface;
    a piezoelectric layer provided on the one main surface of the support substrate;
    a functional electrode provided on at least one main surface of the piezoelectric layer;
    with
    the wiring substrate is electrically connected to the acoustic wave element via the under bump metal layer and the bumps;
    A piezoelectric layer is not provided at least partly between the bump and the support substrate in the stacking direction of the support substrate and the piezoelectric layer,
    An elastic wave device, wherein the dielectric layer has a thickness of 150 nm or more in a portion where the piezoelectric layer is not provided.
  2. 　請求項１に記載の弾性波装置であって、
    　前記誘電層は、前記圧電層が設けられている部分と前記圧電層が設けられていない部分とで同一の材料からなる
    　弾性波装置。     The elastic wave device according to claim 1,
    The elastic wave device, wherein the dielectric layer is made of the same material in a portion where the piezoelectric layer is provided and a portion where the piezoelectric layer is not provided.
  3. 　請求項１又は請求項２に記載の弾性波装置であって、
    　前記圧電層が設けられている部分の前記誘電層の最大厚みが、前記圧電層の最大厚みの２倍以上である
    　弾性波装置。     The elastic wave device according to claim 1 or claim 2,
    The elastic wave device, wherein the maximum thickness of the dielectric layer in the portion where the piezoelectric layer is provided is at least twice the maximum thickness of the piezoelectric layer.
  4. 　請求項１から請求項３のいずれか１項に記載の弾性波装置であって、
    　前記圧電層は、圧電体の単結晶からなる
    　弾性波装置。     The elastic wave device according to any one of claims 1 to 3,
    The piezoelectric layer is an elastic wave device made of a piezoelectric single crystal.
  5. 　請求項１から請求項４のいずれか１項に記載の弾性波装置であって、
    　前記誘電層は、酸化ケイ素を含む
    　弾性波装置。     The elastic wave device according to any one of claims 1 to 4,
    The acoustic wave device, wherein the dielectric layer includes silicon oxide.
  6. 　請求項１から請求項５のいずれか１項に記載の弾性波装置であって、
    　前記支持基板は、一方主面に空洞部を有し、
    　前記圧電層は、前記空洞部を覆うように前記支持基板の前記一方主面に設けられ、
    　前記機能電極は、前記支持基板と前記圧電層との積層方向から見て、少なくとも一部が前記空洞部と重なるように設けられている
    　弾性波装置。     The elastic wave device according to any one of claims 1 to 5,
    The support substrate has a cavity on one main surface,
    The piezoelectric layer is provided on the one main surface of the support substrate so as to cover the cavity,
    The elastic wave device, wherein the functional electrode is provided so that at least a part of the functional electrode overlaps the hollow portion when viewed from the lamination direction of the support substrate and the piezoelectric layer.
  7. 　請求項６に記載の弾性波装置であって、
    　前記機能電極は、１以上の第１電極と、前記１以上の第１電極が接続された第１のバスバー電極と、１以上の第２電極と、前記１以上の第２電極が接続された第２のバスバー電極と、を有する、
    　弾性波装置。     The elastic wave device according to claim 6,
    The functional electrodes include one or more first electrodes, a first busbar electrode to which the one or more first electrodes are connected, one or more second electrodes, and one or more second electrodes to which the one or more second electrodes are connected. a second busbar electrode;
    Elastic wave device.
  8. 　請求項７に記載の弾性波装置であって、
    　前記圧電層の厚みは、前記１以上の第１電極と前記１以上の第２電極のうち、隣り合う第１電極と第２電極との間の中心間距離をｐとした場合に２ｐ以下である
    　弾性波装置。     The elastic wave device according to claim 7,
    The piezoelectric layer has a thickness of 2p or less where p is the center-to-center distance between the one or more first electrodes and the one or more second electrodes. There is an acoustic wave device.
  9. 　請求項６に記載の弾性波装置であって、
    　前記圧電層が、ニオブ酸リチウムまたはタンタル酸リチウムからなる
    　弾性波装置。     The elastic wave device according to claim 6,
    An acoustic wave device, wherein the piezoelectric layer is made of lithium niobate or lithium tantalate.
  10. 　請求項９に記載の弾性波装置であって、
    　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
    　弾性波装置。     The elastic wave device according to claim 9,
    An elastic wave device configured to be able to utilize bulk waves in a thickness-shlip mode.
  11. 　請求７に記載の弾性波装置であって、
    　前記圧電層の厚みをｄ、前記１以上の第１電極と前記１以上の第２電極のうち、隣り合う第１電極と第２電極との間の中心間距離をｐとした場合、ｄ／ｐ≦０．５である
    　弾性波装置。     The elastic wave device according to claim 7,
    When d is the thickness of the piezoelectric layer and p is the center-to-center distance between the one or more first electrodes and the one or more second electrodes, d/ An elastic wave device wherein p≦0.5.
  12. 　請求項１１に記載の弾性波装置であって、
    　ｄ／ｐ≦０．２４である
    　弾性波装置。     The elastic wave device according to claim 11,
    An elastic wave device wherein d/p≦0.24.
  13. 　請求項７、請求項１１又は請求項１２に記載の弾性波装置であって、
    　前記１以上の第１電極と前記１以上の第２電極のうち、隣り合う第１電極と第２電極とが対向している方向に視たときに重なっている励振領域の面積に対する、前記隣り合う第１電極と第２電極との面積の割合であるメタライゼーション比をＭＲ、前記圧電層の厚みをｄ、前記隣り合う第１電極と第２電極の中心間距離をｐとした場合、ＭＲ≦１．７５（ｄ／ｐ）＋０．０７５である
    　弾性波装置。     The elastic wave device according to claim 7, claim 11, or claim 12,
    of the one or more first electrodes and the one or more second electrodes, with respect to the area of the excitation region where the adjacent first electrodes and the second electrodes overlap when viewed in the facing direction; Let MR be the metallization ratio, which is the ratio of the areas of the first electrode and the second electrode that meet, d be the thickness of the piezoelectric layer, and p be the center-to-center distance between the adjacent first and second electrodes. ≦1.75(d/p)+0.075 An elastic wave device.
  14. 　請求項１３に記載の弾性波装置であって、
    　ＭＲ≦１．７５（ｄ／ｐ）＋０．０５である
    　弾性波装置。     The elastic wave device according to claim 13,
    An elastic wave device in which MR≤1.75(d/p)+0.05.
  15. 　請求項９に記載の弾性波装置であって、
    　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、
    　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）     The elastic wave device according to claim 9,
    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),
    Elastic wave device.
    (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)
  16. 　請求項６に記載の弾性波装置であって、
    　前記機能電極は、前記圧電層の一方の主面に設けられた上部電極と、
    前記圧電層の他方の主面に設けられた下部電極と、を有する
    　弾性波装置。
     
     
          The elastic wave device according to claim 6,
    The functional electrode includes an upper electrode provided on one main surface of the piezoelectric layer;
    and a lower electrode provided on the other principal surface of the piezoelectric layer.
PCT/JP2022/041929 2021-11-11 2022-11-10 Elastic wave device WO2023085364A1 (en)

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JP2013528996A (en) * 2010-04-23 2013-07-11 テクノロジアン テュトキムスケスクス ヴェーテーテー Broadband acoustic coupling thin film BAW filter
WO2015098679A1 (en) * 2013-12-27 2015-07-02 株式会社村田製作所 Elastic wave device and method for manufacturing same
JP2019106698A (en) * 2017-12-12 2019-06-27 株式会社村田製作所 Electronic component module
WO2021200835A1 (en) * 2020-03-30 2021-10-07 株式会社村田製作所 Elastic wave device

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Publication number Priority date Publication date Assignee Title
JP2013528996A (en) * 2010-04-23 2013-07-11 テクノロジアン テュトキムスケスクス ヴェーテーテー Broadband acoustic coupling thin film BAW filter
WO2015098679A1 (en) * 2013-12-27 2015-07-02 株式会社村田製作所 Elastic wave device and method for manufacturing same
JP2019106698A (en) * 2017-12-12 2019-06-27 株式会社村田製作所 Electronic component module
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