WO2022065137A1 - Dispositif à ondes élastiques - Google Patents

Dispositif à ondes élastiques Download PDF

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Publication number
WO2022065137A1
WO2022065137A1 PCT/JP2021/033753 JP2021033753W WO2022065137A1 WO 2022065137 A1 WO2022065137 A1 WO 2022065137A1 JP 2021033753 W JP2021033753 W JP 2021033753W WO 2022065137 A1 WO2022065137 A1 WO 2022065137A1
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WO
WIPO (PCT)
Prior art keywords
wiring
bus bar
elastic wave
idt electrode
width
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PCT/JP2021/033753
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English (en)
Japanese (ja)
Inventor
祐也 平塚
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株式会社村田製作所
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Publication date
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Publication of WO2022065137A1 publication Critical patent/WO2022065137A1/fr

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
    • H03H9/02—Details
    • H03H9/125—Driving means, e.g. electrodes, coils
    • H03H9/145—Driving means, e.g. electrodes, coils for networks using surface acoustic waves

Definitions

  • the present invention relates to an elastic wave device.
  • Patent Document 1 describes an example of a surface acoustic wave filter.
  • This surface acoustic wave filter is a longitudinally coupled resonator type elastic wave filter and has a plurality of IDT (Interdigital Transducer) electrodes. Wiring is connected to one of the bus bars of the pair of bus bars of each IDT electrode. The wirings cross each other three-dimensionally via an insulating film. As a result, a three-dimensional crossing portion is formed. The frequency of the attenuation pole is adjusted by adjusting the capacitance by adjusting the width of the wiring at the flying junction.
  • IDT Interdigital Transducer
  • An object of the present invention is to provide an elastic wave device whose capacitance can be easily adjusted and whose insertion loss does not easily deteriorate.
  • the elastic wave device includes a piezoelectric substrate, an IDT electrode provided on the piezoelectric substrate and having a first bus bar and a second bus bar facing each other, and a plurality of electrode fingers.
  • the first wiring connected to the first bus bar, the insulating film laminated on the first wiring, and the insulating film laminated on the insulating film are electrically insulated from the first wiring.
  • the three-dimensional crossover portion is composed of the first wiring, the insulating film, and the second wiring, and when two or more natural numbers are n, n of the above are provided.
  • the first wiring is provided.
  • the capacitance can be easily adjusted and the insertion loss does not easily deteriorate.
  • FIG. 1 is a plan view of an elastic wave device according to a first embodiment of the present invention.
  • FIG. 2 is an enlarged view of FIG.
  • FIG. 3 is a plan view of the elastic wave device of the comparative example.
  • FIG. 4 is a diagram showing the attenuation frequency characteristics of the elastic wave device of the first embodiment of the present invention and the comparative example.
  • FIG. 5 is a schematic diagram of the first wiring and the first bus bar in the comparative example.
  • FIG. 6 is a schematic diagram of the first wiring and the first bus bar in the first embodiment of the present invention.
  • FIG. 7 is a schematic plan view of an elastic wave device according to a first modification of the first embodiment of the present invention.
  • FIG. 8 is a front sectional view showing the vicinity of a pair of electrode fingers of the first IDT electrode of the elastic wave device according to the second modification of the first embodiment of the present invention.
  • FIG. 1 is a plan view of an elastic wave device according to a first embodiment of the present invention.
  • FIG. 2 is an enlarged view of FIG.
  • the elastic wave device 1 of the present embodiment is used for a filter device, a multiplexer, and the like.
  • FIG. 1 shows a portion of the filter device in which the elastic wave device 1 is arranged.
  • the surface acoustic wave device 1 is a longitudinally coupled resonator type elastic wave filter and is an elastic surface wave device.
  • the elastic wave device according to the present invention is not limited to these.
  • the elastic wave device 1 has a piezoelectric substrate 2.
  • the piezoelectric substrate 2 is a piezoelectric substrate composed of only a piezoelectric layer.
  • the piezoelectric substrate 2 may be a laminated substrate including a piezoelectric layer.
  • the material of the piezoelectric layer for example, lithium tantalate, lithium niobate, zinc oxide, aluminum nitride, quartz, PZT (lead zirconate titanate) or the like can be used.
  • a plurality of IDT electrodes are provided on the piezoelectric substrate 2. More specifically, the plurality of IDT electrodes are a first IDT electrode 3A, a second IDT electrode 3B, a third IDT electrode 3C, a fourth IDT electrode 3D, and a fifth IDT electrode 3E. Elastic waves are excited by applying an AC voltage to each IDT electrode.
  • IDT electrodes are lined up along the elastic wave propagation direction. More specifically, in the elastic wave propagation direction, the first IDT electrode 3A among the plurality of IDT electrodes is located at the center. The second IDT electrode 3B and the third IDT electrode 3C are arranged so as to sandwich the first IDT electrode 3A. Further, a fourth IDT electrode 3D and a fifth IDT electrode 3E are arranged so as to sandwich the first IDT electrode 3A, the second IDT electrode 3B, and the third IDT electrode 3C.
  • a pair of reflectors 13A and 13Bs are provided on both sides of the plurality of IDT electrodes in the elastic wave propagation direction on the piezoelectric substrate 2.
  • the plurality of IDT electrodes and the pair of reflectors 13A and 13B may be made of a laminated metal film or may be made of a single layer metal film.
  • Each IDT electrode has a pair of bus bars and a plurality of electrode fingers.
  • a pair of busbars face each other.
  • the pair of busbars of the first IDT electrode 3A is the first busbar 4A and the second busbar 5A.
  • the plurality of electrode fingers of the first IDT electrode 3A are a plurality of first electrode fingers 6 and a plurality of second electrode fingers 7. One end of each of the plurality of first electrode fingers 6 is connected to the first bus bar 4A. One end of each of the plurality of second electrode fingers 7 is connected to the second bus bar 5A.
  • the plurality of first electrode fingers 6 and the plurality of second electrode fingers 7 are interleaved with each other.
  • the fourth IDT electrode 3D shown in FIG. 1 has a first bus bar 4D and a second bus bar 5D as a pair of bus bars.
  • the fifth IDT electrode 3E has a first bus bar 4E and a second bus bar 5E as a pair of bus bars.
  • Each first bus bar of the first IDT electrode 3A, the fourth IDT electrode 3D and the fifth IDT electrode 3E is electrically connected to the same signal potential.
  • each second bus bar of the first IDT electrode 3A, the fourth IDT electrode 3D and the fifth IDT electrode 3E is electrically connected to the ground potential.
  • the second bus bar is electrically connected to the ground potential via the second wiring 9b.
  • the pair of bus bars in the second IDT electrode 3B are the third bus bar 14B and the fourth bus bar 15B.
  • the pair of busbars in the third IDT electrode 3C are the third busbar 14C and the fourth busbar 15C.
  • one end of a part of the plurality of electrode fingers is connected to a third bus bar, respectively.
  • One end of the remaining part of the plurality of electrode fingers is connected to a fourth bus bar, respectively.
  • Each third bus bar of the second IDT electrode 3B and the third IDT electrode 3C is electrically connected to the ground potential.
  • the third bus bar is electrically connected to the ground potential via the second wiring 9a.
  • each fourth bus bar of the second IDT electrode 3B and the third IDT electrode 3C is electrically connected to the same signal potential.
  • a plurality of first wirings 8A are connected to the first bus bar 4A of the first IDT electrode 3A.
  • the first wiring is two wires.
  • n first wires may be provided.
  • the dimension along the elastic wave propagation direction of the first wiring 8A is defined as the width We of the first wiring 8A.
  • An insulating film 12 is laminated on the n first wirings 8A.
  • the insulating film 12 is made of an inorganic insulator, a resin, or the like.
  • the second wiring 9a is laminated on the insulating film 12.
  • the second wiring 9a is electrically isolated from the n first wirings 8A.
  • the n first wirings 8A and the second wirings 9a are three-dimensionally intersected with each other via the insulating film 12.
  • the three-dimensional crossing portion is composed of the n first wiring 8A, the insulating film 12, and the second wiring 9a.
  • the n first wirings 8A and the second wirings 9a face each other. Therefore, the flying junction functions as a capacitive element.
  • n first wirings 8A are provided, and n first wirings 8A form a flying junction together with the insulating film 12 and the second wiring 9a. There is something in it.
  • the width We of each of the first wirings 8A the facing areas of the first wirings 8A and the second wirings 9a at the flying junction can be easily adjusted. Therefore, the capacity can be easily adjusted.
  • the insertion loss is unlikely to deteriorate in this embodiment.
  • the comparative example differs from the present embodiment in that the first wiring 108 is only one.
  • the width of the first wiring 108 of the comparative example is the same as the total width We of the two first wirings 8A in the present embodiment.
  • FIG. 4 is a diagram showing the attenuation frequency characteristics of the elastic wave device of the first embodiment and the comparative example. In FIG. 4, it is shown that the insertion loss is smaller as the value on the vertical axis is located higher.
  • FIG. 5 is a schematic diagram of the first wiring and the first bus bar in the comparative example.
  • FIG. 6 is a schematic diagram of the first wiring and the first bus bar in the first embodiment.
  • the hatch in FIG. 5 indicates a region in the first bus bar 4A.
  • the dashed arrow E in FIGS. 5 and 6 schematically indicates the current.
  • the width of the first wiring 108 of the comparative example is 2We, which is twice the width We of the first wiring 8A of the first embodiment.
  • the distance from one end of the first bus bar 4A in the elastic wave propagation direction to the first wiring 108 is L1. Therefore, the maximum length of the current path from the first bus bar 4A to the first wiring 108 is L 1 .
  • the longer the current path the greater the electrical resistance.
  • the larger the electrical resistance the larger the insertion loss.
  • the current path from the hatched region in FIG. 5 to the first wiring 108 exceeds L 1/2 and is particularly long.
  • the distance from one end of the first bus bar 4A in the elastic wave propagation direction to the other first wiring 8A is L 1 /. It is 2.
  • the distance from the end portion to the first wiring 8A is the maximum distance from the first bus bar 4A to the first wiring 8A. Therefore, the maximum length of the current path from the first bus bar 4A to the first wiring 8A is L 1/2 .
  • the maximum length of the current path from the first bus bar 4A to the other first wiring 8A is also L 1/2 .
  • the maximum length of the current path in the first embodiment is shorter than the maximum length of the current path of the comparative example.
  • the path of the current from any position of the first bus bar 4A can be shortened. This makes it possible to substantially reduce the electrical resistance. Therefore, even if the width of the first wiring 8A is narrowed in order to adjust the capacitance, the insertion loss is unlikely to deteriorate.
  • the elastic wave device does not function as a filter.
  • the elastic wave device 1 is not easily damaged.
  • the first bus bar 4A has a plurality of openings 4d.
  • the plurality of openings 4d are arranged in the elastic wave propagation direction. More specifically, the first bus bar 4A has an inner bus bar portion 4a, an outer bus bar portion 4b, and a plurality of connection electrodes 4c.
  • the inner bus bar portion 4a and the outer bus bar portion 4b face each other in the direction in which the plurality of electrode fingers extend.
  • the plurality of connection electrodes 4c connect the inner bus bar portion 4a and the outer bus bar portion 4b.
  • the plurality of openings 4d are openings surrounded by an inner bus bar portion 4a, an outer bus bar portion 4b, and a plurality of connection electrodes 4c.
  • the second bus bar 5A also has an inner bus bar portion, an outer bus bar portion, a plurality of connection electrodes, and a plurality of openings.
  • the first bus bar 4A and the second bus bar 5A do not have to have a plurality of openings.
  • the dimension along the direction in which the plurality of electrode fingers of the first bus bar 4A extend is defined as the width Wb of the first bus bar 4A.
  • the width of the outer bus bar portion is defined as the width of the bus bar. It is preferable that the total width We of the n first wirings 8A at the flying junction is equal to or larger than the width Wb of the first bus bar 4A. In this case, the insertion loss is less likely to deteriorate.
  • the width We of the first wiring 8A at the flying junction is preferably Wb / n or less. In this case, the capacity can be adjusted to be even smaller. In this case as well, since the current path can be shortened as shown in FIG. 6, the insertion loss is unlikely to deteriorate. Therefore, the present invention is suitable when the width We of the first wiring 8A is narrow.
  • the width We of the first wiring 8A at the flying junction is preferably not more than the total film thickness of the electrodes, for example, 1 ⁇ m or more. As a result, the first wiring 8A is unlikely to be broken.
  • the width We of each first wiring 8A is the same. However, the width We of each of the first wirings 8A may be different from each other.
  • At least one first wiring 8A is located on one end side of the center of the first bus bar 4A in the elastic wave propagation direction, and at least one other first wiring 8A is the first. It is preferable that the bus bar 4A is located on the other end side of the center in the elastic wave propagation direction. Thereby, the current path can be suitably shortened.
  • n first wirings 8A, an insulating film 12 and a second wiring 9a are laminated in this order from the piezoelectric substrate 2 side.
  • the second wiring 9a, the insulating film 12, and n first wirings 8A may be laminated in this order from the piezoelectric substrate 2 side.
  • first wires 8A are connected to the signal potential, and the second wire 9a is connected to the ground potential.
  • the n first wirings 8A may be connected to the ground potential, and the second wiring 9a may be connected to the signal potential.
  • the third wiring 18 is connected to each of the second bus bars of the first IDT electrode 3A, the fourth IDT electrode 3D, and the fifth IDT electrode 3E. There is.
  • Each third wire 18 is connected to the second wire 9b.
  • the boundary between each bus bar and each third wiring 18 is shown by a alternate long and short dash line.
  • each second bus bar may be directly connected to the second wiring 9b.
  • the third wiring 18 is connected to each of the third bus bars of the second IDT electrode 3B and the third IDT electrode 3C.
  • Each third wire 18 is connected to the second wire 9a.
  • each third bus bar may be directly connected to the second wiring 9a.
  • n first wires are connected to bus bars connected to the signal potentials of all IDT electrodes.
  • two first wirings 8B are connected to the fourth bus bar 15B of the second IDT electrode 3B.
  • the flying junction is composed of two first wirings 8B, an insulating film 12 and a second wiring 9b.
  • the n first wires connected to the other IDT electrodes also form a flying junction together with the insulating film 12 and the second wire. Even at each flying junction, the capacitance can be easily adjusted and the insertion loss is unlikely to deteriorate.
  • it is sufficient that n first wires are connected to one bus bar of at least one IDT electrode. It suffices that the n first wirings together with the insulating film 12 and the second wiring form a three-dimensional crossing portion.
  • the width of the plurality of electrode fingers of each IDT electrode is widened near the end in the direction in which the plurality of electrode fingers extend.
  • the width of the plurality of electrode fingers may be constant.
  • the width of the electrode finger is a dimension along the elastic wave propagation direction of the electrode finger.
  • FIG. 7 is a schematic plan view of the elastic wave device according to the first modification of the first embodiment.
  • the widths of the plurality of first electrode fingers 26 and the plurality of second electrode fingers 27 of the first IDT electrode 23A are constant.
  • the first bus bar 24A and the second bus bar 25A of the first IDT electrode 23A do not have an opening. The same applies to each of the other IDT electrodes. Even in this case, the capacity can be easily adjusted and the insertion loss is unlikely to deteriorate.
  • the piezoelectric substrate 2 is composed of only a piezoelectric layer.
  • the piezoelectric substrate 2 may be a laminated substrate including a piezoelectric layer.
  • FIG. 8 is a front sectional view showing the vicinity of a pair of electrode fingers of the first IDT electrode of the elastic wave device according to the second modification of the first embodiment.
  • the piezoelectric substrate 32 has a support substrate 33, a high sound velocity film 34 as a high sound velocity material layer, a low sound velocity film 35, and a piezoelectric layer 36. More specifically, the high sound velocity film 34 is provided on the support substrate 33. A low sound velocity film 35 is provided on the high sound velocity film 34. The piezoelectric layer 36 is provided on the low sound velocity film 35.
  • the low sound velocity film 35 is a relatively low sound velocity film. More specifically, the speed of sound of the bulk wave propagating in the bass velocity film 35 is lower than the speed of sound of the bulk wave propagating in the piezoelectric layer 36.
  • the material of the low sound velocity film 35 for example, a material containing glass, silicon oxide, silicon nitride, lithium oxide, tantalum pentoxide, or a compound obtained by adding fluorine, carbon, or boron to silicon oxide as a main component is used. Can be done.
  • the high sound velocity material layer is a relatively high sound velocity layer. More specifically, the sound velocity of the bulk wave propagating in the high-pitched material layer is higher than the sound velocity of the elastic wave propagating in the piezoelectric layer 36.
  • the material of the high-pitched material layer include silicon, aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, sapphire, lithium tantalate, lithium niobate, crystal, alumina, zirconia, cordierite, mulite, steatite, and the like.
  • a medium containing the above materials as a main component such as forsterite, magnesia, a DLC (diamond-like carbon) film, or diamond, can be used.
  • Examples of the material of the support substrate 33 include piezoelectric materials such as aluminum oxide, lithium tantalate, lithium niobate, and crystal, alumina, sapphire, magnesia, silicon nitride, aluminum nitride, silicon carbide, zirconia, cordierite, mulite, and steer.
  • Various ceramics such as tight and forsterite, dielectrics such as diamond and glass, semiconductors or resins such as silicon and gallium nitride can be used.
  • the piezoelectric substrate 32 of the second modification the high sound velocity material layer, the low sound velocity film 35, and the piezoelectric layer 36 are laminated. Thereby, the energy of the elastic wave can be effectively confined on the piezoelectric layer 36 side.
  • the capacitance can be easily adjusted and the insertion loss is less likely to deteriorate.
  • the high sound velocity material layer may be a high sound velocity support substrate.
  • the piezoelectric substrate may be a laminated substrate of a high sound velocity support substrate, a low sound velocity film 35, and a piezoelectric layer 36.
  • the piezoelectric layer 36 is indirectly provided on the high sound velocity material layer.
  • the piezoelectric layer 36 may be provided directly on the high sound velocity material layer.
  • the piezoelectric substrate may be a laminated substrate having no low sound velocity film 35.
  • the piezoelectric substrate may be a laminated substrate of a high sound velocity support substrate and a piezoelectric layer 36.
  • the piezoelectric substrate may be a laminated substrate of the support substrate 33, the high sound velocity film 34, and the piezoelectric layer 36. Even in these cases, the energy of the elastic wave can be effectively confined on the piezoelectric layer 36 side. In addition, the capacity can be easily adjusted and the insertion loss is less likely to deteriorate.
  • a laminate of the piezoelectric layer 36 and the acoustic reflection film may be formed.
  • the acoustic reflection film includes at least one low acoustic impedance layer and at least one high acoustic impedance layer.
  • the low acoustic impedance layer is a layer having a relatively low acoustic impedance.
  • the high acoustic impedance layer is a layer having a relatively high acoustic impedance.
  • the low acoustic impedance layer and the high acoustic impedance layer are laminated alternately. Even in this case, the energy of the elastic wave can be effectively confined on the piezoelectric layer 36 side. Further, as in the first embodiment, the capacity can be easily adjusted and the insertion loss is less likely to deteriorate.

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  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Abstract

L'invention fournit un dispositif à ondes élastiques dont la capacité peut être ajustée facilement, et dont l'affaiblissement d'insertion est peu susceptible de se dégrader.　Le dispositif à ondes élastiques (1) de l'invention est équipé : d'un substrat piézoélectrique (2) ; d'une première barre omnibus (4A) ainsi que d'une seconde barre omnibus agencées sur le substrat piézoélectrique (2) et s'opposant ; d'une première électrode de transducteur interdigital (3A) possédant une pluralité de premiers ainsi que de seconds doigts d'électrode (6, 7) ; d'un premier câblage (8A) connecté à la première barre omnibus (4A) ; d'un film isolant (12) stratifié sur le premier câblage (8A) ; et d'un second câblage (9a) stratifié sur le film isolant (12), et isolé électriquement du premier câblage (8A). Une partie intersection sur différents niveaux est configurée par le premier câblage (8A), le film isolant (12) et le second câblage (9a). Lorsqu'un entier naturel supérieur ou égal à 2 est représenté par n, alors n premiers câblages (8A) sont agencés.
PCT/JP2021/033753 2020-09-28 2021-09-14 Dispositif à ondes élastiques WO2022065137A1 (fr)

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JP2020162237 2020-09-28
JP2020-162237 2020-09-28

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024098786A1 (fr) * 2022-11-09 2024-05-16 华为技术有限公司 Résonateur à ondes acoustiques de surface, filtre et dispositif électronique

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007259023A (ja) * 2006-03-23 2007-10-04 Matsushita Electric Ind Co Ltd 弾性表面波フィルタ及びそれを用いた通信機器
WO2010150882A1 (fr) * 2009-06-26 2010-12-29 京セラ株式会社 Filtre à ondes acoustiques de surface et filtre d'aiguillage utilisant ledit filtre
WO2019123811A1 (fr) * 2017-12-19 2019-06-27 株式会社村田製作所 Dispositif à ondes élastiques

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007259023A (ja) * 2006-03-23 2007-10-04 Matsushita Electric Ind Co Ltd 弾性表面波フィルタ及びそれを用いた通信機器
WO2010150882A1 (fr) * 2009-06-26 2010-12-29 京セラ株式会社 Filtre à ondes acoustiques de surface et filtre d'aiguillage utilisant ledit filtre
WO2019123811A1 (fr) * 2017-12-19 2019-06-27 株式会社村田製作所 Dispositif à ondes élastiques

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024098786A1 (fr) * 2022-11-09 2024-05-16 华为技术有限公司 Résonateur à ondes acoustiques de surface, filtre et dispositif électronique

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