WO2022158370A1 - Elastic wave device - Google Patents

Elastic wave device Download PDF

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Publication number
WO2022158370A1
WO2022158370A1 PCT/JP2022/000942 JP2022000942W WO2022158370A1 WO 2022158370 A1 WO2022158370 A1 WO 2022158370A1 JP 2022000942 W JP2022000942 W JP 2022000942W WO 2022158370 A1 WO2022158370 A1 WO 2022158370A1
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electrode
wave device
elastic wave
electrode fingers
layer
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PCT/JP2022/000942
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French (fr)
Japanese (ja)
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克也 大門
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株式会社村田製作所
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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
    • 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 an acoustic wave device in which reflectors are provided on both sides of an IDT electrode.
  • FIGS. 33A to 33C of the patent document disclose a configuration in which a capacitor is connected between a pair of bus bars of IDT electrodes. This capacitor is formed by providing a pair of electrodes that overlap each other via a dielectric on the piezoelectric body in a region away from the region where the IDT electrodes and the reflector are provided.
  • the capacitance is configured outside the region where the IDT electrodes and reflectors are provided. Therefore, a large space is required on the piezoelectric body, and miniaturization has been difficult.
  • An object of the present invention is to provide an elastic wave device that can be miniaturized.
  • An elastic wave device comprises a substrate having a piezoelectric layer, IDT electrodes provided on the piezoelectric layer, and first and second electrodes disposed on both sides of the IDT electrodes on the piezoelectric layer.
  • 2 reflectors wherein the IDT electrode comprises a first bus bar, a second bus bar provided separated from the first bus bar, and a plurality of wires connected to the first bus bar It has a first electrode finger and a plurality of second electrode fingers connected to the second bus bar, and each of the first and second reflectors includes the plurality of electrode fingers and the plurality of a first connecting portion commonly connecting one end sides of the electrode fingers; and a second connecting portion commonly connecting the other end sides of the plurality of electrode fingers;
  • a comb tooth electrode portion is formed between the connection portion or the second connection portion and the first bus bar or the second bus bar of the IDT electrode, and the comb tooth electrode portion is connected to the first bus bar.
  • the comb tooth has a plurality of third electrode fingers connected to the second bus bar
  • FIG. 1 is a plan view of an elastic wave device according to a first embodiment of the invention.
  • FIG. 2 is a plan view of an elastic wave device according to a modification of the first embodiment;
  • FIG. 3 is a front sectional view of the elastic wave device of the first embodiment of the invention.
  • FIG. 4 is a schematic plan view showing a state in which the dielectric film is removed in the elastic wave device of the first embodiment of the invention.
  • FIG. 5 is a partially cutaway front cross-sectional view for explaining a modification of the elastic wave device of the first embodiment of the present invention.
  • FIG. 6 is a partially cutaway plan view showing the main part of the elastic wave device according to the second embodiment of the present invention.
  • FIG. 7 is a diagram showing impedance characteristics of elastic wave devices of Examples and Comparative Examples.
  • FIG. 1 is a plan view of an elastic wave device according to a first embodiment of the invention.
  • FIG. 2 is a plan view of an elastic wave device according to a modification of the first embodiment
  • FIG. 8 is a schematic plan view for explaining the electrode structure of the acoustic wave device according to the third embodiment of the invention.
  • FIG. 9 is a partially cutaway plan view for explaining an elastic wave device according to a fourth embodiment of the present invention.
  • FIG. 10 is a front cross-sectional view of an elastic wave device according to a fifth embodiment of the invention.
  • FIG. 11 is a front cross-sectional view of an acoustic wave device according to a sixth embodiment of the invention.
  • FIG. 1 is a plan view of an elastic wave device according to a first embodiment of the present invention
  • FIG. 3 is a front cross-sectional view thereof.
  • the elastic wave device 1 includes a substrate 6 having a piezoelectric layer 5 , IDT electrodes 7 provided on the piezoelectric layer 5 , and first and second reflectors 8 and 9 .
  • the first and second reflectors 8 and 9 are arranged on both sides of the IDT electrode 7 in the elastic wave propagation direction. This constitutes a one-port elastic wave resonator.
  • the IDT electrode 7 includes a first bus bar 11, a second bus bar 12 separated from the first bus bar 11, a plurality of first electrode fingers 13 and a plurality of second electrode fingers. 14.
  • the plurality of first electrode fingers 13 has one end connected to the first bus bar 11 and the other end extending toward the second bus bar 12 side.
  • One end of the plurality of second electrode fingers 14 is connected to the second busbar 12 and the other end extends toward the first busbar 11 side.
  • the plurality of first electrode fingers 13 and the plurality of second electrode fingers 14 are interdigitated.
  • the elastic wave propagation direction is a direction perpendicular to the direction in which the plurality of first and second electrode fingers 13 and 14 extend.
  • a region where the first electrode fingers 13 and the second electrode fingers 14 overlap when viewed in the elastic wave propagation direction is the intersection region K.
  • FIG. In the intersecting region K elastic waves are excited by applying an AC electric field between the first electrode finger 13 and the second electrode finger 14 .
  • the intersecting area K includes a central area C, a first low-pitched velocity area E1 provided on the first busbar 11 side of the central area C, and a second low-pitched velocity area E2 provided on the second busbar 12 side. and The sound velocities of the first and second low sound velocity areas E1 and E2 are lower than that of the central area C. As shown in FIG.
  • the first and second dielectric layers 15 and 16 are provided in order to lower the sound velocity of the first and second low sound velocity regions E1 and E2.
  • the sound velocities of the outer regions F1 and F2 of the first and second low sound speed regions E1 and E2 are higher than those of the first and second low sound speed regions E1 and E2.
  • the dielectric for forming the first and second dielectric layers 15 and 16 is not particularly limited, and silicon oxide, tantalum pentoxide, hafnium oxide, tungsten oxide, etc. can be used.
  • a dielectric film 10 may be provided in the central region C, as shown in FIG. In that case, the dielectric film 10 can use titanium dioxide, silicon carbide, silicon nitride, or the like as a dielectric material.
  • the first reflector 8 includes a plurality of electrode fingers 8a, a first connecting portion 17 commonly connecting one end side of the plurality of electrode fingers 8a, and a second connecting portion 17 commonly connecting the other end side of the plurality of electrode fingers 8a. and a connection portion 18 of .
  • the multiple electrode fingers 8 a extend in the same direction as the multiple first electrode fingers 13 and the multiple second electrode fingers 14 of the IDT electrode 7 .
  • the second connecting portion 18 has a strip-like shape extending in the elastic wave propagation direction. That is, it has the same shape as the first and second busbars 11 and 12 .
  • the first connecting portion 17 is composed of a comb-teeth electrode in this embodiment. That is, it has a plurality of fourth electrode fingers 17b. In one of the plurality of fourth electrode fingers 17b, the plurality of electrode fingers 8a are commonly connected at one end thereof. A plurality of fourth electrode fingers 17 b are formed extending from the first bus bar 11 toward the first connecting portion 17 . The plurality of third electrode fingers 17a and the plurality of fourth electrode fingers 17b are interdigitated to form a comb-teeth electrode portion. The plurality of third electrode fingers 17a and the plurality of fourth electrode fingers 17b are extended along the elastic wave propagation direction.
  • the third and fourth electrode fingers 17a, 17b extend in a direction orthogonal to the plurality of electrode fingers forming the first or second reflectors 8,9.
  • One end of the plurality of third electrode fingers 17 a is electrically connected to the first bus bar 11 .
  • One ends of the plurality of fourth electrode fingers 17 b are connected in common and connected to the first reflector 8 .
  • FIG. 4 is a schematic plan view of the acoustic wave device 1 with the dielectric film 19 removed.
  • a capacitance is formed by the first connection portion 17 between the first reflector 8 and the first bus bar 11 of the IDT electrode 7 . That is, a capacitance is formed by the comb-teeth electrode portion and the dielectric film 19 provided on the comb-teeth electrode portion.
  • both ends of a plurality of electrode fingers 9a are connected by third and fourth connection portions 17A and 18A.
  • the third and fourth connecting portions 17A, 18A are configured similarly to the second connecting portion 18. As shown in FIG.
  • the comb tooth electrode portion is provided between the first bus bar 11 and the first reflector 8 on the side of the IDT electrode 7 . That is, the comb-teeth electrode portion is provided in a region corresponding to the region where the first connection portion 17 is provided. Therefore, on the piezoelectric layer 5, a large space for forming capacitance is not required other than the space where the IDT electrode 7 and the first and second reflectors 8 and 9 are provided. Therefore, the elastic wave device 1 can be miniaturized in spite of having the above capacity.
  • the dielectric film 19 an appropriate dielectric that can increase the capacitance can be used, and is not particularly limited.
  • the dielectric material forming the dielectric film 19 has a higher dielectric constant than the material forming the piezoelectric layer 5 .
  • a dielectric material one selected from the group consisting of tantalum pentoxide, hafnium oxide, niobium pentoxide, and titanium dioxide is more preferably used. In that case, the capacity can be further increased, and the miniaturization can be further advanced.
  • the dielectric material forming the dielectric film 19 and the dielectric material forming the first and second dielectric layers 15 and 16 are made of the same material. In that case, the first and second dielectric layers 15 and 16 and the dielectric film 19 can be formed by the same process.
  • the substrate 6 has a laminated structure of a high acoustic velocity member layer 3 and a low acoustic velocity film 4 as an intermediate layer laminated between the supporting substrate 2 and the piezoelectric layer 5 .
  • the support substrate 2 is made of an appropriate insulating material such as silicon or alumina or a semiconductor material.
  • the high acoustic velocity member layer 3 is made of a high acoustic velocity material.
  • a high acoustic velocity material is a material in which the acoustic velocity of a propagating bulk wave is higher than the acoustic velocity of an elastic wave propagating through the piezoelectric layer 5 .
  • Such high sonic materials include aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, silicon, sapphire, lithium tantalate, lithium niobate, quartz, alumina, zirconia, cordierite, mullite, steatite, fort.
  • the high acoustic velocity member layer 3 is made of SiN.
  • the low sound velocity film 4 is made of a low sound velocity material.
  • a low sound velocity material is a material in which a propagating bulk wave has a lower acoustic velocity than a bulk wave propagating through the piezoelectric layer 5 .
  • Such low sound velocity materials include silicon oxide, glass, silicon oxynitride, tantalum oxide, compounds obtained by adding fluorine, carbon, boron, hydrogen, or silanol groups to silicon oxide, and media containing the above materials as main components. etc. can be used.
  • the low sound velocity film 4 is made of silicon oxide.
  • the piezoelectric layer 5 is made of piezoelectric single crystal such as LiTaO 3 or LiNbO 3 .
  • the piezoelectric layer 5 is made of LiTaO 3 .
  • the intermediate layer is composed of a laminate of the high acoustic velocity member layer 3 and the low acoustic velocity film 4, but it is also possible to use only the low acoustic velocity membrane 4 as the intermediate layer and configure the support substrate 2 from a high acoustic velocity material.
  • the support substrate 2 and the high acoustic velocity member layer 3 may be integrally formed of a high acoustic velocity material.
  • the IDT electrode 7 and the first and second reflectors 8 and 9 are made of an appropriate metal or alloy. A laminate of a plurality of metal layers may also be used. In this embodiment, the IDT electrode 7 and the first and second reflectors 8 and 9 are composed of a laminate of Ti film/AlCu film/Ti film.
  • FIG. 5 is a partially cutaway front cross-sectional view for explaining a modification of the elastic wave device of the first embodiment.
  • a protective layer 21 is provided so as to cover the IDT electrodes 7 .
  • This protective layer 21 can be composed of a suitable dielectric such as silicon oxide.
  • a dielectric material with a positive temperature coefficient of frequency is used, such as silicon oxide. In that case, the frequency temperature characteristics of the elastic wave device can be improved.
  • FIG. 6 is a partially cutaway plan view for explaining the essential parts of the elastic wave device according to the second embodiment of the present invention.
  • FIG. 6 shows an enlarged portion where the IDT electrode 37 and the first reflector 38 are provided.
  • the IDT electrode 37 has first and second busbars 41 and 42 .
  • the first busbar 41 connects the inner busbar portion 41a positioned on the crossing region K side, the outer busbar portion 41b positioned outside, and the inner busbar portion 41a and the outer busbar portion 41b. and a portion 41c.
  • a plurality of openings 41d are provided in the elastic wave propagation direction.
  • a connecting portion 41c is provided between the adjacent openings 41d.
  • the second busbar 42 also has an inner busbar portion 42a, an outer busbar portion 42b, and a connecting portion 42c. Also, a plurality of openings 42d are provided along the elastic wave propagation direction.
  • the second connecting portion 48 has a similar configuration. That is, it has an inner busbar portion 48a, an outer busbar portion 48b, and a connecting portion 48c, and an opening 48d is provided between the connecting portions 48c.
  • the second connection portion 48 is a portion that commonly connects a plurality of electrode fingers 38a. The second connection portion 48 does not connect the first reflector 38 and the IDT electrode 37 .
  • an inner busbar portion 47a, a connecting portion 47c, and an opening 47d are provided, and the outer end of the connecting portion 47c is connected to the comb-teeth electrode portion. That is, the outer end of the connecting portion 47c is connected to one of the plurality of fourth electrode fingers 47f forming the comb-teeth electrode portion.
  • the plurality of third electrode fingers 47e are connected to the first bus bar 41 as in the first embodiment.
  • a dielectric film is provided to cover the comb-teeth electrode portion, as in the first embodiment.
  • FIG. 6 shows the configuration between the connection portion of the IDT electrode 37 and the first reflector 38
  • the connection portion of the second reflector is configured similarly to the second connection portion 48 .
  • the first connection portion 47 has a comb-teeth electrode structure and a dielectric film covering the comb-teeth electrode portion is provided.
  • a capacitance can be formed between one reflector 38 .
  • this portion constitutes the capacitance, the acoustic wave device 31 can also be made smaller.
  • the elastic wave device 1 of the first embodiment was manufactured with the following design parameters.
  • Support substrate Si High sound velocity member layer: SiN film, thickness 900 nm Low sound velocity film: SiO2 film, film thickness is 600nm
  • Piezoelectric layer LiTaO 3 film, film thickness: 600 nm, orientation: 50° Y-cut X-propagation IDT electrode 7, first reflector 8, and second reflector have a laminated structure of Ti film/AlCu film/Ti film The film thickness is 12 nm/140 nm/4 nm from the piezoelectric layer side.
  • the wavelength ⁇ determined by the electrode finger pitch of the IDT electrode 7 is 2 ⁇ m, the duty is 0.5, and the number of electrode finger pairs is 100 pairs.
  • the intersection width, which is the dimension of the intersection region K, is 20 ⁇ .
  • the dielectric film provided on the first connection portion 17 was a Ta 2 O 5 film with a thickness of 25 nm.
  • Ta 2 O 5 films were laminated as first and second dielectric layers in the first and second low-temperature regions E 1 and E 2 of the IDT electrode 7 .
  • the film thickness was set to 25 nm.
  • the dimension in the cross width direction of the first and second low-pitched sound velocity regions E1 and E2 was set to 0.6 ⁇ .
  • an acoustic wave device of a comparative example was produced in the same manner as in the above example, except that the first connection portion was made the same as the second connection portion.
  • FIG. 7 is a diagram showing impedance characteristics of the elastic wave devices of the above examples and comparative examples.
  • the anti-resonance frequency is shifted to the low frequency side in the example as compared with the comparative example. That is, since a capacitance is inserted between the IDT electrode 7 and the first reflector 8, it is possible to narrow the fractional band.
  • the impedance of the example is lower than that of the comparative example. For this reason, when forming IDT electrodes having the same capacitance value, in the embodiment, the number of pairs of IDT electrodes in the propagation direction of the elastic wave is reduced, or the crossing width, which is the width of the crossing region in the direction in which the electrode fingers extend, is reduced. can be reduced, and miniaturization is possible.
  • FIG. 8 is a schematic plan view for explaining the electrode structure of the acoustic wave device according to the third embodiment of the invention.
  • illustration of the dielectric film laminated on the comb-teeth electrode portion is omitted.
  • the first connection portion 17 has a capacitance.
  • the second connection portion 18 also has comb-teeth electrode portions.
  • the third connection portion 17A and the fourth connection portion 18A have comb-teeth electrode portions.
  • a capacitance is formed at each of the connection portions on both sides in the direction in which the electrode fingers 8a of the first reflector 8 extend and on both sides in the direction in which the electrode fingers 9a of the second reflector 9 extend.
  • the capacitors composed of the comb-teeth electrode portion and the dielectric film may be provided in all of the first and second connection portions of the first and second reflectors.
  • a capacitor may be formed in at least one connection portion among the plurality of connection portions as in the first embodiment.
  • FIG. 9 is a partially cutaway plan view showing an elastic wave device according to a fourth embodiment of the present invention.
  • the first and second dielectric layers 15 and 16 are laminated in the first and second low-frequency regions E1 and E2 in order to suppress the transverse mode.
  • the elastic wave device 61 shown in FIG. 9 the second electrode finger 14 and the first electrode finger 13 are provided with wide portions 14m and 13m in the first and second low-frequency regions E1 and E2, respectively.
  • the sound velocities of the first and second low sound velocity regions E1 and E2 are lowered.
  • the first and second low-frequency regions E1 and E2 may have a structure in which the electrode fingers are partially widened.
  • FIG. 10 is a front cross-sectional view of an elastic wave device according to a fifth embodiment of the invention.
  • intermediate layer 72 is provided between piezoelectric layer 5 and support substrate 2 .
  • the intermediate layer 72 is a laminate of high acoustic impedance layers 72a, 72c, 72e with relatively high acoustic impedance and low acoustic impedance layers 72b, 72d, 72f with relatively low acoustic impedance.
  • the intermediate layer 72 which is such an acoustic reflection layer, may be used.
  • FIG. 11 is a front cross-sectional view of an acoustic wave device according to a sixth embodiment of the invention.
  • the elastic wave device 81 is a piezoelectric substrate in which the entire substrate 82 having a piezoelectric layer is made of a piezoelectric material. That is, in the present invention, the substrate may be composed of a piezoelectric single crystal such as LiTaO 3 or LiNbO 3 .

Abstract

Provided is an elastic wave device that can be reduced in size.　This elastic wave device 1 comprises a substrate 6 having a piezoelectric layer 5, an IDT electrode 7, and first and second reflectors 8, 9, the elastic wave device 1 being such that: a first bus bar 11 or a second bus bar 12 of the IDT electrode 7, and at least one of first and second connecting parts 17, 18 at both ends of the first and second reflectors 8, 9, have a comb electrode part; the comb electrode part has a plurality of third electrode fingers 17a connected to the first or second bus bar 11, 12, and a plurality of fourth electrode fingers 17b connected to the first or second connecting part 17, 18; and a dielectric film 19 is provided so as to cover the comb electrode part.

Description

弾性波装置Acoustic wave device
　本発明は、ＩＤＴ電極の両側に反射器が設けられた弾性波装置に関する。 The present invention relates to an acoustic wave device in which reflectors are provided on both sides of an IDT electrode.
　下記の特許文献１に記載の弾性波装置では、当該特許文献の図３３Ａ～Ｃに、ＩＤＴ電極の一対のバスバー間に容量が接続されている構成が開示されている。この容量は、ＩＤＴ電極や反射器が設けられている領域から離れた領域において、圧電体上において誘電体を介して重なり合う一対の電極を設けることにより構成されている。 In the elastic wave device described in Patent Document 1 below, FIGS. 33A to 33C of the patent document disclose a configuration in which a capacitor is connected between a pair of bus bars of IDT electrodes. This capacitor is formed by providing a pair of electrodes that overlap each other via a dielectric on the piezoelectric body in a region away from the region where the IDT electrodes and the reflector are provided.
特開２０１６－２６４４４号公報JP 2016-26444 A
　特許文献１に記載の弾性波装置では、ＩＤＴ電極や反射器が設けられている領域の外側において上記容量が構成されていた。そのため、圧電体上に大きなスペースを必要とし、小型化が困難であった。 In the elastic wave device described in Patent Literature 1, the capacitance is configured outside the region where the IDT electrodes and reflectors are provided. Therefore, a large space is required on the piezoelectric body, and miniaturization has been difficult.
　本発明の目的は、小型化を図り得る弾性波装置を提供することにある。 An object of the present invention is to provide an elastic wave device that can be miniaturized.
　本発明に係る弾性波装置は、圧電体層を有する基板と、前記圧電体層上に設けられたＩＤＴ電極と、前記圧電体層上において、前記ＩＤＴ電極の両側に配置された第１，第２の反射器と、を備え、前記ＩＤＴ電極が、第１のバスバーと、前記第１のバスバーと隔てられて設けられた第２のバスバーと、前記第１のバスバーに接続された複数本の第１の電極指と、前記第２のバスバーに接続された複数本の第２の電極指とを有し、前記第１，第２の反射器は、それぞれ複数本の電極指と、前記複数本の電極指の一端側を共通接続している第１の接続部と、前記複数本の電極指の他端側を共通接続している第２の接続部とを有し、前記第１の接続部または前記第２の接続部と、前記ＩＤＴ電極の前記第１のバスバーまたは前記第２のバスバーとの間に櫛歯電極部が構成されており、前記櫛歯電極部が、前記第１または前記第２のバスバーに接続された複数本の第３の電極指と、前記第１または前記第２の接続部に接続された複数本の第４の電極指とを有し、前記櫛歯電極部を覆うように設けられた誘電体膜をさらに備える。 An elastic wave device according to the present invention comprises a substrate having a piezoelectric layer, IDT electrodes provided on the piezoelectric layer, and first and second electrodes disposed on both sides of the IDT electrodes on the piezoelectric layer. 2 reflectors, wherein the IDT electrode comprises a first bus bar, a second bus bar provided separated from the first bus bar, and a plurality of wires connected to the first bus bar It has a first electrode finger and a plurality of second electrode fingers connected to the second bus bar, and each of the first and second reflectors includes the plurality of electrode fingers and the plurality of a first connecting portion commonly connecting one end sides of the electrode fingers; and a second connecting portion commonly connecting the other end sides of the plurality of electrode fingers; A comb tooth electrode portion is formed between the connection portion or the second connection portion and the first bus bar or the second bus bar of the IDT electrode, and the comb tooth electrode portion is connected to the first bus bar. Alternatively, the comb tooth has a plurality of third electrode fingers connected to the second bus bar and a plurality of fourth electrode fingers connected to the first or second connection portion. A dielectric film provided to cover the electrode portion is further provided.
　本発明によれば、小型化を図り得る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 elastic wave device that can be miniaturized.
図１は、本発明の第１の実施形態に係る弾性波装置の平面図である。FIG. 1 is a plan view of an elastic wave device according to a first embodiment of the invention. 図２は、第１の実施形態の変形例に係る弾性波装置の平面図である。FIG. 2 is a plan view of an elastic wave device according to a modification of the first embodiment; 図３は、本発明の第１の実施形態の弾性波装置の正面断面図である。FIG. 3 is a front sectional view of the elastic wave device of the first embodiment of the invention. 図４は、本発明の第１の実施形態の弾性波装置において、誘電体膜を除去した状態を示す模式的平面図である。FIG. 4 is a schematic plan view showing a state in which the dielectric film is removed in the elastic wave device of the first embodiment of the invention. 図５は、本発明の第１の実施形態の弾性波装置の変形例を説明するための部分切欠き正面断面図である。FIG. 5 is a partially cutaway front cross-sectional view for explaining a modification of the elastic wave device of the first embodiment of the present invention. 図６は、本発明の第２の実施形態に係る弾性波装置の要部を示す部分切欠き平面図である。FIG. 6 is a partially cutaway plan view showing the main part of the elastic wave device according to the second embodiment of the present invention. 図７は、実施例及び比較例の弾性波装置のインピーダンス特性を示す図である。FIG. 7 is a diagram showing impedance characteristics of elastic wave devices of Examples and Comparative Examples. 図８は、本発明の第３の実施形態の弾性波装置の電極構造を説明するための模式的平面図である。FIG. 8 is a schematic plan view for explaining the electrode structure of the acoustic wave device according to the third embodiment of the invention. 図９は、本発明の第４の実施形態の弾性波装置を説明するための部分切欠き平面図である。FIG. 9 is a partially cutaway plan view for explaining an elastic wave device according to a fourth embodiment of the present invention. 図１０は、本発明の第５の実施形態に係る弾性波装置の正面断面図である。FIG. 10 is a front cross-sectional view of an elastic wave device according to a fifth embodiment of the invention. 図１１は、本発明の第６の実施形態に係る弾性波装置の正面断面図である。FIG. 11 is a front cross-sectional view of an acoustic wave device according to a sixth embodiment of the invention.
　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.
　なお、本明細書に記載の各実施形態は、例示的なものであり、異なる実施形態間において、構成の部分的な置換または組み合わせが可能であることを指摘しておく。 It should be noted that each embodiment described in this specification is an example, and partial replacement or combination of configurations is possible between different embodiments.
　図１は、本発明の第１の実施形態に係る弾性波装置の平面図であり、図３はその正面断面図である。 1 is a plan view of an elastic wave device according to a first embodiment of the present invention, and FIG. 3 is a front cross-sectional view thereof.
　弾性波装置１は、圧電体層５を有する基板６と、圧電体層５上に設けられたＩＤＴ電極７と、第１，第２の反射器８，９とを備える。 The elastic wave device 1 includes a substrate 6 having a piezoelectric layer 5 , IDT electrodes 7 provided on the piezoelectric layer 5 , and first and second reflectors 8 and 9 .
　図１に示すように、第１，第２の反射器８，９は、ＩＤＴ電極７の弾性波伝搬方向両側に配置されている。それによって、１ポート型の弾性波共振子が構成されている。 As shown in FIG. 1, the first and second reflectors 8 and 9 are arranged on both sides of the IDT electrode 7 in the elastic wave propagation direction. This constitutes a one-port elastic wave resonator.
　ＩＤＴ電極７は、第１のバスバー１１と、第１のバスバー１１とは隔てられて設けられた第２のバスバー１２と、複数本の第１の電極指１３及び複数本の第２の電極指１４とを有する。複数本の第１の電極指１３は、一端が第１のバスバー１１に接続されており、他端が第２のバスバー１２側に向かって延ばされている。複数本の第２の電極指１４の一端が第２のバスバー１２に接続されており、他端が第１のバスバー１１側に向かって延ばされている。複数本の第１の電極指１３と複数本の第２の電極指１４とは、間挿し合っている。 The IDT electrode 7 includes a first bus bar 11, a second bus bar 12 separated from the first bus bar 11, a plurality of first electrode fingers 13 and a plurality of second electrode fingers. 14. The plurality of first electrode fingers 13 has one end connected to the first bus bar 11 and the other end extending toward the second bus bar 12 side. One end of the plurality of second electrode fingers 14 is connected to the second busbar 12 and the other end extends toward the first busbar 11 side. The plurality of first electrode fingers 13 and the plurality of second electrode fingers 14 are interdigitated.
　弾性波伝搬方向は、複数本の第１，第２の電極指１３，１４が延びる方向と直交する方向である。この弾性波伝搬方向にみたときに、第１の電極指１３と第２の電極指１４とが重なり合っている領域が、交叉領域Ｋである。交叉領域Ｋでは、第１の電極指１３と第２の電極指１４との間に交流電界を印加することにより、弾性波が励振される。交叉領域Ｋは、中央領域Ｃと、中央領域Ｃの第１のバスバー１１側に設けられた第１の低音速領域Ｅ１と、第２のバスバー１２側に設けられた第２の低音速領域Ｅ２とを有する。第１，第２の低音速領域Ｅ１，Ｅ２の音速は、中央領域Ｃより低められている。本実施形態では、第１，第２の低音速領域Ｅ１，Ｅ２の音速を低めるために、第１，第２の誘電体層１５，１６が設けられている。第１，第２の低音速領域Ｅ１，Ｅ２の外側の領域Ｆ１，Ｆ２の音速は、第１，第２の低音速領域Ｅ１，Ｅ２よりも高音速となる。それによって、ＩＤＴ電極７では、横モードによるリップルを抑制することができる。 The elastic wave propagation direction is a direction perpendicular to the direction in which the plurality of first and second electrode fingers 13 and 14 extend. A region where the first electrode fingers 13 and the second electrode fingers 14 overlap when viewed in the elastic wave propagation direction is the intersection region K. FIG. In the intersecting region K, elastic waves are excited by applying an AC electric field between the first electrode finger 13 and the second electrode finger 14 . The intersecting area K includes a central area C, a first low-pitched velocity area E1 provided on the first busbar 11 side of the central area C, and a second low-pitched velocity area E2 provided on the second busbar 12 side. and The sound velocities of the first and second low sound velocity areas E1 and E2 are lower than that of the central area C. As shown in FIG. In this embodiment, the first and second dielectric layers 15 and 16 are provided in order to lower the sound velocity of the first and second low sound velocity regions E1 and E2. The sound velocities of the outer regions F1 and F2 of the first and second low sound speed regions E1 and E2 are higher than those of the first and second low sound speed regions E1 and E2. Thereby, the IDT electrode 7 can suppress the ripple due to the transverse mode.
　第１，第２の誘電体層１５，１６を構成するための誘電体としては、特に限定されず、酸化ケイ素、五酸化タンタル、酸化ハフニウム、酸化タングステンなどを用いることができる。あるいは、図２に示すように、中央領域Ｃに誘電体膜１０を設けてもよい。その場合、当該誘電体膜１０は、誘電体の材料として、二酸化チタン、炭化ケイ素、窒化ケイ素などを用いることができる。 The dielectric for forming the first and second dielectric layers 15 and 16 is not particularly limited, and silicon oxide, tantalum pentoxide, hafnium oxide, tungsten oxide, etc. can be used. Alternatively, a dielectric film 10 may be provided in the central region C, as shown in FIG. In that case, the dielectric film 10 can use titanium dioxide, silicon carbide, silicon nitride, or the like as a dielectric material.
　第１の反射器８は、複数本の電極指８ａと、複数本の電極指８ａの一端側を共通接続している第１の接続部１７と、他端側を共通接続している第２の接続部１８とを有する。複数本の電極指８ａは、ＩＤＴ電極７が有する複数本の第１の電極指１３及び複数本の第２の電極指１４と同じ方向に延びている。ここで、第２の接続部１８は、弾性波伝搬方向に延びるストリップ状の形状を有している。すなわち、第１，第２のバスバー１１，１２と同様の形状を有している。 The first reflector 8 includes a plurality of electrode fingers 8a, a first connecting portion 17 commonly connecting one end side of the plurality of electrode fingers 8a, and a second connecting portion 17 commonly connecting the other end side of the plurality of electrode fingers 8a. and a connection portion 18 of . The multiple electrode fingers 8 a extend in the same direction as the multiple first electrode fingers 13 and the multiple second electrode fingers 14 of the IDT electrode 7 . Here, the second connecting portion 18 has a strip-like shape extending in the elastic wave propagation direction. That is, it has the same shape as the first and second busbars 11 and 12 .
　他方、第１の接続部１７は、本実施形態では櫛歯電極により構成されている。すなわち、複数本の第４の電極指１７ｂを有する。そして、当該複数本の第４の電極指１７ｂのうちの１本において、複数本の電極指８ａがその一端側で共通接続されている。また、第１のバスバー１１から、複数本の第４の電極指１７ｂが、第１の接続部１７に向かって延びて形成される。これらの複数本の第３の電極指１７ａと、複数本の第４の電極指１７ｂとが間挿し合って、櫛歯電極部となっている。複数本の第３の電極指１７ａ及び複数本の第４の電極指１７ｂは、弾性波伝搬方向に沿って延ばされている。すなわち、第３及び第４の電極指１７ａ，１７ｂは、第１または第２の反射器８，９を構成している複数本の電極指と直交する方向に延びている。複数本の第３の電極指１７ａは、第１のバスバー１１に一端が電気的に接続されている。複数本の第４の電極指１７ｂの一端は共通接続され、第１の反射器８に接続されている。 On the other hand, the first connecting portion 17 is composed of a comb-teeth electrode in this embodiment. That is, it has a plurality of fourth electrode fingers 17b. In one of the plurality of fourth electrode fingers 17b, the plurality of electrode fingers 8a are commonly connected at one end thereof. A plurality of fourth electrode fingers 17 b are formed extending from the first bus bar 11 toward the first connecting portion 17 . The plurality of third electrode fingers 17a and the plurality of fourth electrode fingers 17b are interdigitated to form a comb-teeth electrode portion. The plurality of third electrode fingers 17a and the plurality of fourth electrode fingers 17b are extended along the elastic wave propagation direction. That is, the third and fourth electrode fingers 17a, 17b extend in a direction orthogonal to the plurality of electrode fingers forming the first or second reflectors 8,9. One end of the plurality of third electrode fingers 17 a is electrically connected to the first bus bar 11 . One ends of the plurality of fourth electrode fingers 17 b are connected in common and connected to the first reflector 8 .
　櫛歯電極部を覆うように、誘電体膜１９が積層されている。図４は、誘電体膜１９を除去した状態の弾性波装置１の模式的平面図である。図１及び図４から明らかなように、第１の反射器８と、ＩＤＴ電極７の第１のバスバー１１との間で、上記第１の接続部１７により容量が形成される。すなわち、櫛歯電極部と、櫛歯電極部上に設けられた誘電体膜１９により、静電容量が形成される。 A dielectric film 19 is laminated so as to cover the comb-teeth electrode portion. FIG. 4 is a schematic plan view of the acoustic wave device 1 with the dielectric film 19 removed. As is clear from FIGS. 1 and 4, a capacitance is formed by the first connection portion 17 between the first reflector 8 and the first bus bar 11 of the IDT electrode 7 . That is, a capacitance is formed by the comb-teeth electrode portion and the dielectric film 19 provided on the comb-teeth electrode portion.
　第２の反射器９では、複数本の電極指９ａの両端が第３，第４の接続部１７Ａ，１８Ａにより接続されている。第３，第４の接続部１７Ａ，１８Ａは、第２の接続部１８と同様に構成されている。 In the second reflector 9, both ends of a plurality of electrode fingers 9a are connected by third and fourth connection portions 17A and 18A. The third and fourth connecting portions 17A, 18A are configured similarly to the second connecting portion 18. As shown in FIG.
　上記櫛歯電極部は、ＩＤＴ電極７の側方において、第１のバスバー１１と、第１の反射器８との間に設けられている。すなわち、当該櫛歯電極部は、第１の接続部１７が設けられている領域に相当する領域に設けられている。そのため、圧電体層５上において、ＩＤＴ電極７及び第１，第２の反射器８，９が設けられているスペースの外に、大きな容量形成用のスペースを必要としない。従って、弾性波装置１では、上記容量を設けたにもかかわらず、小型化を図ることができる。 The comb tooth electrode portion is provided between the first bus bar 11 and the first reflector 8 on the side of the IDT electrode 7 . That is, the comb-teeth electrode portion is provided in a region corresponding to the region where the first connection portion 17 is provided. Therefore, on the piezoelectric layer 5, a large space for forming capacitance is not required other than the space where the IDT electrode 7 and the first and second reflectors 8 and 9 are provided. Therefore, the elastic wave device 1 can be miniaturized in spite of having the above capacity.
　上記誘電体膜１９としては、容量を高め得る適宜の誘電体を用いることができ、特に限定されない。好ましくは、誘電体膜１９を構成する誘電体材料は、圧電体層５を構成している材料よりも誘電率が高い材料が用いられる。このような誘電体材料としては、より好ましくは、五酸化タンタル、酸化ハフニウム、五酸化ニオブ、及び二酸化チタンからなる群から選択された一種が用いられる。その場合には、容量をより一層高くすることができ、小型化をさらに進めることができる。 As the dielectric film 19, an appropriate dielectric that can increase the capacitance can be used, and is not particularly limited. Preferably, the dielectric material forming the dielectric film 19 has a higher dielectric constant than the material forming the piezoelectric layer 5 . As such a dielectric material, one selected from the group consisting of tantalum pentoxide, hafnium oxide, niobium pentoxide, and titanium dioxide is more preferably used. In that case, the capacity can be further increased, and the miniaturization can be further advanced.
　また、好ましくは、誘電体膜１９を構成する誘電体材料と、第１，第２の誘電体層１５，１６を構成している誘電体材料が同じ材料からなる。その場合には、同一プロセスにより、第１，第２の誘電体層１５，１６と、誘電体膜１９とを形成することができる。 Also, preferably, the dielectric material forming the dielectric film 19 and the dielectric material forming the first and second dielectric layers 15 and 16 are made of the same material. In that case, the first and second dielectric layers 15 and 16 and the dielectric film 19 can be formed by the same process.
　図３に示すように、基板６は、支持基板２と圧電体層５との間に積層される中間層として、高音速部材層３及び低音速膜４の積層構造を有する。支持基板２は、シリコン、アルミナなどの適宜の絶縁性材料や半導体材料からなる。 As shown in FIG. 3, the substrate 6 has a laminated structure of a high acoustic velocity member layer 3 and a low acoustic velocity film 4 as an intermediate layer laminated between the supporting substrate 2 and the piezoelectric layer 5 . The support substrate 2 is made of an appropriate insulating material such as silicon or alumina or a semiconductor material.
　高音速部材層３は、高音速材料からなる。高音速材料とは、伝搬するバルク波の音速が、圧電体層５を伝搬する弾性波の音速よりも高い材料をいう。このような高音速材料としては、酸化アルミニウム、炭化ケイ素、窒化ケイ素、酸窒化ケイ素、シリコン、サファイア、タンタル酸リチウム、ニオブ酸リチウム、水晶、アルミナ、ジルコニア、コ－ジライト、ムライト、ステアタイト、フォルステライト、マグネシア、ＤＬＣ（ダイヤモンドライクカーボン）膜またはダイヤモンド、上記材料を主成分とする媒質、上記材料の混合物を主成分とする媒質等の様々な材料を用いることができる。本実施形態では、高音速部材層３は、ＳｉＮからなる。 The high acoustic velocity member layer 3 is made of a high acoustic velocity material. A high acoustic velocity material is a material in which the acoustic velocity of a propagating bulk wave is higher than the acoustic velocity of an elastic wave propagating through the piezoelectric layer 5 . Such high sonic materials include aluminum oxide, silicon carbide, silicon nitride, silicon oxynitride, silicon, sapphire, lithium tantalate, lithium niobate, quartz, alumina, zirconia, cordierite, mullite, steatite, fort. Various materials such as stellite, magnesia, a DLC (diamond-like carbon) film or diamond, a medium containing the above materials as a main component, and a medium containing a mixture of the above materials as a main component can be used. In this embodiment, the high acoustic velocity member layer 3 is made of SiN.
　低音速膜４は、低音速材料からなる。低音速材料とは、伝搬するバルク波の音速が、圧電体層５を伝搬するバルク波の音速よりも低い材料をいう。このような低音速材料としては、酸化ケイ素、ガラス、酸窒化ケイ素、酸化タンタル、また、酸化ケイ素にフッ素や炭素やホウ素、水素、あるいはシラノール基を加えた化合物、上記材料を主成分とする媒質等の様々な材料を用いることができる。本実施形態では、低音速膜４は酸化ケイ素からなる。 The low sound velocity film 4 is made of a low sound velocity material. A low sound velocity material is a material in which a propagating bulk wave has a lower acoustic velocity than a bulk wave propagating through the piezoelectric layer 5 . Such low sound velocity materials include silicon oxide, glass, silicon oxynitride, tantalum oxide, compounds obtained by adding fluorine, carbon, boron, hydrogen, or silanol groups to silicon oxide, and media containing the above materials as main components. etc. can be used. In this embodiment, the low sound velocity film 4 is made of silicon oxide.
　圧電体層５は、ＬｉＴａＯ３またはＬｉＮｂＯ３などの圧電単結晶からなる。本実施形態では、圧電体層５は、ＬｉＴａＯ３からなる。 The piezoelectric layer 5 is made of piezoelectric single crystal such as LiTaO 3 or LiNbO 3 . In this embodiment, the piezoelectric layer 5 is made of LiTaO 3 .
　中間層は、高音速部材層３と低音速膜４との積層体からなるが、中間層として低音速膜４のみを用い、支持基板２を高音速材料で構成してもよい。すなわち、支持基板２と高音速部材層３とを高音速材料で一体に構成してもよい。 The intermediate layer is composed of a laminate of the high acoustic velocity member layer 3 and the low acoustic velocity film 4, but it is also possible to use only the low acoustic velocity membrane 4 as the intermediate layer and configure the support substrate 2 from a high acoustic velocity material. In other words, the support substrate 2 and the high acoustic velocity member layer 3 may be integrally formed of a high acoustic velocity material.
　ＩＤＴ電極７及び第１，第２の反射器８，９は、適宜の金属もしくは合金からなる。また複数の金属層の積層体を用いてもよい。本実施形態では、ＩＤＴ電極７及び第１，第２の反射器８，９は、Ｔｉ膜／ＡｌＣｕ膜／Ｔｉ膜の積層体からなる。 The IDT electrode 7 and the first and second reflectors 8 and 9 are made of an appropriate metal or alloy. A laminate of a plurality of metal layers may also be used. In this embodiment, the IDT electrode 7 and the first and second reflectors 8 and 9 are composed of a laminate of Ti film/AlCu film/Ti film.
　図５は、第１の実施形態の弾性波装置の変形例を説明するための部分切欠き正面断面図である。本変形例に係る弾性波装置２０では、ＩＤＴ電極７を覆うように保護層２１が設けられている。この保護層２１は、酸化ケイ素などの適宜の誘電体により構成することができる。好ましくは、酸化ケイ素のように、周波数温度係数が正の誘電体材料が用いられる。その場合には、弾性波装置における周波数温度特性を改善することができる。 FIG. 5 is a partially cutaway front cross-sectional view for explaining a modification of the elastic wave device of the first embodiment. In the elastic wave device 20 according to this modified example, a protective layer 21 is provided so as to cover the IDT electrodes 7 . This protective layer 21 can be composed of a suitable dielectric such as silicon oxide. Preferably, a dielectric material with a positive temperature coefficient of frequency is used, such as silicon oxide. In that case, the frequency temperature characteristics of the elastic wave device can be improved.
　図６は、本発明の第２の実施形態に係る弾性波装置の要部を説明するための部分切欠き平面図である。図６では、ＩＤＴ電極３７と、第１の反射器３８とが設けられている部分が拡大して示されている。第２の実施形態の弾性波装置３１では、ＩＤＴ電極３７は、第１，第２のバスバー４１，４２を有する。第１のバスバー４１は、交叉領域Ｋ側に位置している内側バスバー部４１ａと、外側に位置している外側バスバー部４１ｂと、内側バスバー部４１ａと外側バスバー部４１ｂとを連結している連結部４１ｃとを有する。弾性波伝搬方向において、複数の開口４１ｄが設けられている。この隣り合う開口４１ｄ間に、連結部４１ｃが設けられている。 FIG. 6 is a partially cutaway plan view for explaining the essential parts of the elastic wave device according to the second embodiment of the present invention. FIG. 6 shows an enlarged portion where the IDT electrode 37 and the first reflector 38 are provided. In the elastic wave device 31 of the second embodiment, the IDT electrode 37 has first and second busbars 41 and 42 . The first busbar 41 connects the inner busbar portion 41a positioned on the crossing region K side, the outer busbar portion 41b positioned outside, and the inner busbar portion 41a and the outer busbar portion 41b. and a portion 41c. A plurality of openings 41d are provided in the elastic wave propagation direction. A connecting portion 41c is provided between the adjacent openings 41d.
　第２のバスバー４２も同様に、内側バスバー部４２ａ、外側バスバー部４２ｂ及び連結部４２ｃを有する。また、複数の開口４２ｄが弾性波伝搬方向に沿って設けられている。 Similarly, the second busbar 42 also has an inner busbar portion 42a, an outer busbar portion 42b, and a connecting portion 42c. Also, a plurality of openings 42d are provided along the elastic wave propagation direction.
　第１の反射器３８においても、第２の接続部４８は同様の構成を有する。すなわち、内側バスバー部４８ａ、外側バスバー部４８ｂ及び連結部４８ｃを有し、連結部４８ｃ間が開口４８ｄとされている。第２の接続部４８は、複数本の電極指３８ａを共通接続している部分である。第２の接続部４８は、第１の反射器３８と、ＩＤＴ電極３７とを接続してはいない。 Also in the first reflector 38, the second connecting portion 48 has a similar configuration. That is, it has an inner busbar portion 48a, an outer busbar portion 48b, and a connecting portion 48c, and an opening 48d is provided between the connecting portions 48c. The second connection portion 48 is a portion that commonly connects a plurality of electrode fingers 38a. The second connection portion 48 does not connect the first reflector 38 and the IDT electrode 37 .
　他方、第１の接続部４７側においては、内側バスバー部４７ａと連結部４７ｃと開口４７ｄが設けられているが、連結部４７ｃの外側端が、櫛歯電極部に接続されている。すなわち、連結部４７ｃの外側端が、櫛歯電極部を構成している複数本の第４の電極指４７ｆのうち１本に接続されている。なお、複数本の第３の電極指４７ｅは、第１の実施形態の場合と同様に、第１のバスバー４１に接続されている。図６では図示を省略しているが、この櫛歯電極部を覆うように、第１の実施形態と同様に誘電体膜が設けられる。 On the other hand, on the side of the first connecting portion 47, an inner busbar portion 47a, a connecting portion 47c, and an opening 47d are provided, and the outer end of the connecting portion 47c is connected to the comb-teeth electrode portion. That is, the outer end of the connecting portion 47c is connected to one of the plurality of fourth electrode fingers 47f forming the comb-teeth electrode portion. The plurality of third electrode fingers 47e are connected to the first bus bar 41 as in the first embodiment. Although not shown in FIG. 6, a dielectric film is provided to cover the comb-teeth electrode portion, as in the first embodiment.
　図６では、ＩＤＴ電極３７と第１の反射器３８の接続部の間の構成を示したが、第２の反射器の接続部は、第２の接続部４８と同様に構成されている。 Although FIG. 6 shows the configuration between the connection portion of the IDT electrode 37 and the first reflector 38 , the connection portion of the second reflector is configured similarly to the second connection portion 48 .
　弾性波装置３１のその他の構成は、弾性波装置１と同様である。本実施形態においても、上記第１の接続部４７が櫛歯電極構造を有し、かつ櫛歯電極部を覆う誘電体膜が設けられているため、ＩＤＴ電極３７の第１のバスバー４１と第１の反射器３８との間に容量を形成することができる。しかも、この部分で容量が構成されるので、弾性波装置３１においても小型化を図ることができる。 Other configurations of the elastic wave device 31 are the same as those of the elastic wave device 1 . Also in the present embodiment, the first connection portion 47 has a comb-teeth electrode structure and a dielectric film covering the comb-teeth electrode portion is provided. A capacitance can be formed between one reflector 38 . Moreover, since this portion constitutes the capacitance, the acoustic wave device 31 can also be made smaller.
　次に、第１の実施形態についての実施例と比較例の特性を説明する。第１の実施形態の弾性波装置１を以下の設計パラメータで作製した。 Next, characteristics of examples and comparative examples of the first embodiment will be described. The elastic wave device 1 of the first embodiment was manufactured with the following design parameters.
　支持基板：Ｓｉ
　高音速部材層：ＳｉＮ膜、厚み９００ｎｍ
　低音速膜：ＳｉＯ２膜、膜厚は６００ｎｍ
　圧電体層：ＬｉＴａＯ３膜、膜厚は６００ｎｍ、方位は５０°ＹカットＸ伝搬
　ＩＤＴ電極７及び第１の反射器８及び第２の反射器の積層構成は、Ｔｉ膜／ＡｌＣｕ膜／Ｔｉ膜で、膜厚は、圧電体層側から１２ｎｍ／１４０ｎｍ／４ｎｍ。 Support substrate: Si
High sound velocity member layer: SiN film, thickness 900 nm
Low sound velocity film: SiO2 film, film thickness is 600nm
Piezoelectric layer: LiTaO 3 film, film thickness: 600 nm, orientation: 50° Y-cut X-propagation IDT electrode 7, first reflector 8, and second reflector have a laminated structure of Ti film/AlCu film/Ti film The film thickness is 12 nm/140 nm/4 nm from the piezoelectric layer side.
　ＩＤＴ電極７の電極指ピッチで定まる波長λは２μｍ、デューティは０．５、電極指の対数は１００対。交叉領域Ｋの寸法である交叉幅は２０λ。 The wavelength λ determined by the electrode finger pitch of the IDT electrode 7 is 2 μm, the duty is 0.5, and the number of electrode finger pairs is 100 pairs. The intersection width, which is the dimension of the intersection region K, is 20λ.
　第１の接続部１７に設けた誘電体膜はＴａ２Ｏ５膜からなり、その膜厚は２５ｎｍとした。 The dielectric film provided on the first connection portion 17 was a Ta 2 O 5 film with a thickness of 25 nm.
　またＩＤＴ電極７の第１，第２の低音速領域Ｅ１，Ｅ２において、第１，第２の誘電体層としてＴａ２Ｏ５膜を積層した。膜厚は２５ｎｍとした。また第１，第２の低音速領域Ｅ１，Ｅ２の交叉幅方向の寸法は０．６λとした。 Also, Ta 2 O 5 films were laminated as first and second dielectric layers in the first and second low-temperature regions E 1 and E 2 of the IDT electrode 7 . The film thickness was set to 25 nm. Also, the dimension in the cross width direction of the first and second low-pitched sound velocity regions E1 and E2 was set to 0.6λ.
　比較のために、第１の接続部を第２の接続部と同様としたことを除いては、上記実施例と同様にして比較例の弾性波装置を作製した。 For comparison, an acoustic wave device of a comparative example was produced in the same manner as in the above example, except that the first connection portion was made the same as the second connection portion.
　図７は、上記実施例及び比較例の弾性波装置のインピーダンス特性を示す図である。図７から明らかなように、比較例に比べ、実施例では、反共振周波数が低周波数側にシフトしている。すなわち、上記ＩＤＴ電極７と第１の反射器８との間に容量が挿入されているため、比帯域を狭めることが可能とされている。また、実施例は比較例に比べて、インピーダンスが下がっている。このため、同じ容量値を有するＩＤＴ電極を形成する場合に、実施例においては、弾性波の伝搬方向におけるＩＤＴ電極の対数を少なくする、あるいは、交叉領域の電極指延伸方向における幅である交叉幅の寸法を小さくすることができ、小型化が可能となる。 FIG. 7 is a diagram showing impedance characteristics of the elastic wave devices of the above examples and comparative examples. As is clear from FIG. 7, the anti-resonance frequency is shifted to the low frequency side in the example as compared with the comparative example. That is, since a capacitance is inserted between the IDT electrode 7 and the first reflector 8, it is possible to narrow the fractional band. Moreover, the impedance of the example is lower than that of the comparative example. For this reason, when forming IDT electrodes having the same capacitance value, in the embodiment, the number of pairs of IDT electrodes in the propagation direction of the elastic wave is reduced, or the crossing width, which is the width of the crossing region in the direction in which the electrode fingers extend, is reduced. can be reduced, and miniaturization is possible.
　図８は、本発明の第３の実施形態に係る弾性波装置の電極構造を説明するための模式的平面図である。ここでは、櫛歯電極部に積層される誘電体膜の図示は省略している。第１の実施形態では、第１の接続部１７においてのみ容量が構成されていた。これに対して、図８に示す弾性波装置５１では、ＩＤＴ電極７と第１の反射器８とが、第１の接続部１７及び第２の接続部１８の双方において、間に容量を挿入する形で接続されている。すなわち、第２の接続部１８もまた、櫛歯電極部を有する。また、第２の反射器９側においても、第３の接続部１７Ａ及び第４の接続部１８Ａが櫛歯電極部を有している。従って、第１の反射器８の電極指８ａの延びる方向両側及び第２の反射器９の電極指９ａの延びる方向両側の各接続部において容量が形成される。このように、本発明においては、櫛歯電極部及び誘電体膜からなる容量は、第１，第２の反射器の第１，第２の接続部の全てに設けられていてもよい。また、複数の接続部のうち少なくとも１つの接続部において第１の実施形態のように容量が形成されていてもよい。 FIG. 8 is a schematic plan view for explaining the electrode structure of the acoustic wave device according to the third embodiment of the invention. Here, illustration of the dielectric film laminated on the comb-teeth electrode portion is omitted. In the first embodiment, only the first connection portion 17 has a capacitance. On the other hand, in the acoustic wave device 51 shown in FIG. connected in such a way that That is, the second connection portion 18 also has comb-teeth electrode portions. Also, on the second reflector 9 side, the third connection portion 17A and the fourth connection portion 18A have comb-teeth electrode portions. Accordingly, a capacitance is formed at each of the connection portions on both sides in the direction in which the electrode fingers 8a of the first reflector 8 extend and on both sides in the direction in which the electrode fingers 9a of the second reflector 9 extend. As described above, in the present invention, the capacitors composed of the comb-teeth electrode portion and the dielectric film may be provided in all of the first and second connection portions of the first and second reflectors. Also, a capacitor may be formed in at least one connection portion among the plurality of connection portions as in the first embodiment.
　図９は、本発明の第４の実施形態に係る弾性波装置を示す部分切欠き平面図である。第１の実施形態では、横モードを抑圧するために、第１，第２の低音速領域Ｅ１，Ｅ２において第１，第２の誘電体層１５，１６が積層されていた。図９に示す弾性波装置６１では、第１，第２の低音速領域Ｅ１，Ｅ２において、それぞれ、第２の電極指１４及び第１の電極指１３に太幅部１４ｍ，１３ｍが設けられている。それによって、第１，第２の低音速領域Ｅ１，Ｅ２の音速が低められている。このように、第１，第２の低音速領域Ｅ１，Ｅ２は、電極指の一部の幅を広げた構造であってもよい。 FIG. 9 is a partially cutaway plan view showing an elastic wave device according to a fourth embodiment of the present invention. In the first embodiment, the first and second dielectric layers 15 and 16 are laminated in the first and second low-frequency regions E1 and E2 in order to suppress the transverse mode. In the elastic wave device 61 shown in FIG. 9, the second electrode finger 14 and the first electrode finger 13 are provided with wide portions 14m and 13m in the first and second low-frequency regions E1 and E2, respectively. there is As a result, the sound velocities of the first and second low sound velocity regions E1 and E2 are lowered. Thus, the first and second low-frequency regions E1 and E2 may have a structure in which the electrode fingers are partially widened.
　図１０は、本発明の第５の実施形態に係る弾性波装置の正面断面図である。弾性波装置７１では、圧電体層５と、支持基板２との間に中間層７２が設けられている。中間層７２は、相対的に音響インピーダンスが高い高音響インピーダンス層７２ａ，７２ｃ，７２ｅと、相対的に音響インピーダンスが低い低音響インピーダンス層７２ｂ，７２ｄ，７２ｆとの積層体からなる。このような音響反射層である中間層７２を用いてもよい。 FIG. 10 is a front cross-sectional view of an elastic wave device according to a fifth embodiment of the invention. In elastic wave device 71 , intermediate layer 72 is provided between piezoelectric layer 5 and support substrate 2 . The intermediate layer 72 is a laminate of high acoustic impedance layers 72a, 72c, 72e with relatively high acoustic impedance and low acoustic impedance layers 72b, 72d, 72f with relatively low acoustic impedance. The intermediate layer 72, which is such an acoustic reflection layer, may be used.
　図１１は、本発明の第６の実施形態に係る弾性波装置の正面断面図である。弾性波装置８１では、圧電体層を有する基板８２の全体が圧電体からなる、圧電基板である。すなわち、本発明では、ＬｉＴａＯ３やＬｉＮｂＯ３などの圧電単結晶により基板を構成してもよい。 FIG. 11 is a front cross-sectional view of an acoustic wave device according to a sixth embodiment of the invention. The elastic wave device 81 is a piezoelectric substrate in which the entire substrate 82 having a piezoelectric layer is made of a piezoelectric material. That is, in the present invention, the substrate may be composed of a piezoelectric single crystal such as LiTaO 3 or LiNbO 3 .
１…弾性波装置
２…支持基板
３…高音速部材層
４…低音速膜
５…圧電体層
６…基板
７…ＩＤＴ電極
８，９…第１，第２の反射器
８ａ，９ａ…電極指
１０…誘電体膜
１１，１２…第１，第２のバスバー
１３，１４…第１，第２の電極指
１３ｍ，１４ｍ…太幅部
１５，１６…第１，第２の誘電体層
１７，１８…第１，第２の接続部
１７Ａ，１８Ａ…第３，第４の接続部
１７ａ，１７ｂ…第３，第４の電極指
１９…誘電体膜
２０…弾性波装置
２１…保護層
３１…弾性波装置
３７…ＩＤＴ電極
３８…第１の反射器
３８ａ…電極指
４１，４２…第１，第２のバスバー
４１ａ，４２ａ，４７ａ，４８ａ…内側バスバー部
４１ｂ，４２ｂ，４８ｂ…外側バスバー部
４１ｃ，４２ｃ，４７ｃ，４８ｃ…連結部
４１ｄ，４２ｄ，４７ｄ，４８ｄ…開口
４７，４８…第１，第２の接続部
４７ｅ，４７ｆ…第３，第４の電極指
５１，６１，７１，８１…弾性波装置
７２…中間層
７２ａ，７２ｃ，７２ｅ…高音響インピーダンス層
７２ｂ，７２ｄ，７２ｆ…低音響インピーダンス層
８２…基板 REFERENCE SIGNS LIST 1 elastic wave device 2 supporting substrate 3 high acoustic velocity member layer 4 low acoustic velocity film 5 piezoelectric layer 6 substrate 7 IDT electrodes 8, 9 first and second reflectors 8a, 9a electrode fingers REFERENCE SIGNS LIST 10: Dielectric films 11, 12: First and second bus bars 13, 14: First and second electrode fingers 13m, 14m: Wide portions 15, 16: First and second dielectric layers 17, Reference Signs List 18 First and second connecting portions 17A, 18A Third and fourth connecting portions 17a, 17b Third and fourth electrode fingers 19 Dielectric film 20 Elastic wave device 21 Protective layer 31 Elastic wave device 37... IDT electrode 38... first reflector 38a... electrode fingers 41, 42... first and second busbars 41a, 42a, 47a, 48a... inner busbar portions 41b, 42b, 48b... outer busbar portion 41c , 42c, 47c, 48c... Connecting parts 41d, 42d, 47d, 48d... Openings 47, 48... First and second connecting parts 47e, 47f... Third and fourth electrode fingers 51, 61, 71, 81... Elastic wave device 72 Intermediate layers 72a, 72c, 72e High acoustic impedance layers 72b, 72d, 72f Low acoustic impedance layer 82 Substrate

Claims (13)

  1. 　圧電体層を有する基板と、
    　前記圧電体層上に設けられたＩＤＴ電極と、
    　前記圧電体層上において、前記ＩＤＴ電極の両側に配置された第１，第２の反射器と、を備え、
    　前記ＩＤＴ電極が、第１のバスバーと、前記第１のバスバーと隔てられて設けられた第２のバスバーと、前記第１のバスバーに接続された複数本の第１の電極指と、前記第２のバスバーに接続された複数本の第２の電極指とを有し、
    　前記第１，第２の反射器は、それぞれ複数本の電極指と、前記複数本の電極指の一端側を共通接続している第１の接続部と、前記複数本の電極指の他端側を共通接続している第２の接続部とを有し、
    　前記第１の接続部または前記第２の接続部と、前記ＩＤＴ電極の前記第１のバスバーまたは前記第２のバスバーとの間に櫛歯電極部が構成されており、前記櫛歯電極部が、前記第１または前記第２のバスバーに接続された複数本の第３の電極指と、前記第１または前記第２の接続部に接続された複数本の第４の電極指とを有し、
    　前記櫛歯電極部を覆うように設けられた誘電体膜をさらに備える、弾性波装置。     a substrate having a piezoelectric layer;
    an IDT electrode provided on the piezoelectric layer;
    and first and second reflectors arranged on both sides of the IDT electrode on the piezoelectric layer,
    The IDT electrodes comprise a first bus bar, a second bus bar separated from the first bus bar, a plurality of first electrode fingers connected to the first bus bar, and the first electrode fingers. and a plurality of second electrode fingers connected to two bus bars,
    The first and second reflectors each include a plurality of electrode fingers, a first connection portion commonly connecting one end side of the plurality of electrode fingers, and the other end of the plurality of electrode fingers. and a second connection connecting the sides in common,
    A comb tooth electrode portion is formed between the first connection portion or the second connection portion and the first bus bar or the second bus bar of the IDT electrode, and the comb tooth electrode portion , a plurality of third electrode fingers connected to the first or the second bus bar, and a plurality of fourth electrode fingers connected to the first or the second connection portion. ,
    An acoustic wave device, further comprising a dielectric film provided so as to cover the comb tooth electrode portion.
  2. 　前記第３及び前記第４の電極指が前記第１または前記第２の反射器を構成している前記複数本の電極指と直交する方向に延びている、請求項１に記載の弾性波装置。 2. The elastic wave device according to claim 1, wherein said third and said fourth electrode fingers extend in a direction orthogonal to said plurality of electrode fingers forming said first or said second reflector. .
  3. 　前記第１，第２の電極指の延びる方向と直交する方向にみたときに、前記ＩＤＴ電極の前記第１の電極指と前記第２の電極指とが重なり合っている部分が交叉領域であり、前記交叉領域が、中央領域と、前記第１，第２の電極指の延びる方向一方側に配置された第１の低音速領域と、他方側に配置された第２の低音速領域とを有する、請求項１または２に記載の弾性波装置。 When viewed in a direction perpendicular to the direction in which the first and second electrode fingers extend, a portion where the first electrode finger and the second electrode finger of the IDT electrode overlap is an intersection region, The intersecting region has a central region, a first low sound velocity region arranged on one side in the direction in which the first and second electrode fingers extend, and a second low sound velocity region arranged on the other side. The elastic wave device according to claim 1 or 2.
  4. 　前記第１，第２の低音速領域において、前記第１，第２の電極指を覆うように誘電体層が設けられている、請求項３に記載の弾性波装置。 The elastic wave device according to claim 3, wherein a dielectric layer is provided so as to cover the first and second electrode fingers in the first and second low-frequency regions.
  5. 　前記中央領域において、前記第１，第２の電極指を覆うように誘電体層が設けられている、請求項３に記載の弾性波装置。 The elastic wave device according to claim 3, wherein a dielectric layer is provided in said central region so as to cover said first and second electrode fingers.
  6. 　前記誘電体膜と前記誘電体層が同じ材料からなる、請求項４または５に記載の弾性波装置。 The elastic wave device according to claim 4 or 5, wherein the dielectric film and the dielectric layer are made of the same material.
  7. 　前記誘電体膜を構成する誘電体材料が、前記圧電体層を構成している材料よりも誘電率が高い、請求項１～６のいずれか１項に記載の弾性波装置。 The elastic wave device according to any one of claims 1 to 6, wherein the dielectric material forming the dielectric film has a higher dielectric constant than the material forming the piezoelectric layer.
  8. 　前記誘電体材料が、五酸化タンタル、酸化ハフニウム、五酸化ニオブ、二酸化チタンからなる群から選択された一種の材料である、請求項７に記載の弾性波装置。 The acoustic wave device according to claim 7, wherein the dielectric material is a material selected from the group consisting of tantalum pentoxide, hafnium oxide, niobium pentoxide, and titanium dioxide.
  9. 　前記基板が、前記圧電体層と、支持基板と、前記圧電体層と前記支持基板との間に積層された中間層とを備える、請求項１～８のいずれか１項に記載の弾性波装置。 The elastic wave according to any one of claims 1 to 8, wherein the substrate comprises the piezoelectric layer, a support substrate, and an intermediate layer laminated between the piezoelectric layer and the support substrate. Device.
  10. 　前記中間層が、伝搬するバルク波の音速が、前記圧電体層を伝搬するバルク波の音速よりも低い低音速材料からなる低音速膜と、
    　伝搬するバルク波の音速が、前記圧電体層を伝搬する弾性波の音速よりも高い高音速材料からなる高音速部材層とを有する、請求項９に記載の弾性波装置。     a low sound velocity film, wherein the intermediate layer is made of a low sound velocity material in which the sound velocity of the propagating bulk wave is lower than the sound velocity of the bulk wave propagating through the piezoelectric layer;
    10. The elastic wave device according to claim 9, further comprising a high acoustic velocity member layer made of a high acoustic velocity material whose acoustic velocity of propagating bulk waves is higher than the acoustic velocity of elastic waves propagating through said piezoelectric layer.
  11. 　前記高音速部材層と前記支持基板とが前記高音速材料により一体化されている、請求項１０に記載の弾性波装置。 The elastic wave device according to claim 10, wherein the high acoustic velocity member layer and the support substrate are integrated with the high acoustic velocity material.
  12. 　前記中間層が、相対的に音響インピーダンスが低い低音響インピーダンス層と、相対的に音響インピーダンスが高い高音響インピーダンス層との積層体を有する、請求項９に記載の弾性波装置。 The elastic wave device according to claim 9, wherein the intermediate layer has a laminate of a low acoustic impedance layer with relatively low acoustic impedance and a high acoustic impedance layer with relatively high acoustic impedance.
  13. 　前記基板が、前記圧電体層からなる圧電基板である、請求項１～８のいずれか１項に記載の弾性波装置。 The elastic wave device according to any one of claims 1 to 8, wherein the substrate is a piezoelectric substrate made of the piezoelectric layer.
PCT/JP2022/000942 2021-01-22 2022-01-13 Elastic wave device WO2022158370A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024029360A1 (en) * 2022-08-04 2024-02-08 株式会社村田製作所 Elastic wave device and filter device

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH077369A (en) * 1993-06-16 1995-01-10 Murata Mfg Co Ltd Surface acoustic wave filter
WO2012127793A1 (en) * 2011-03-22 2012-09-27 パナソニック株式会社 Elastic wave element
JP2017199984A (en) * 2016-04-25 2017-11-02 株式会社村田製作所 Acoustic wave device
WO2019065667A1 (en) * 2017-09-27 2019-04-04 株式会社村田製作所 Acoustic wave filter device
JP2019121873A (en) * 2017-12-28 2019-07-22 太陽誘電株式会社 Elastic wave device, filter, and multiplexer
JP2020053876A (en) * 2018-09-27 2020-04-02 京セラ株式会社 Acoustic wave device, demultiplexer, and communication device

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH077369A (en) * 1993-06-16 1995-01-10 Murata Mfg Co Ltd Surface acoustic wave filter
WO2012127793A1 (en) * 2011-03-22 2012-09-27 パナソニック株式会社 Elastic wave element
JP2017199984A (en) * 2016-04-25 2017-11-02 株式会社村田製作所 Acoustic wave device
WO2019065667A1 (en) * 2017-09-27 2019-04-04 株式会社村田製作所 Acoustic wave filter device
JP2019121873A (en) * 2017-12-28 2019-07-22 太陽誘電株式会社 Elastic wave device, filter, and multiplexer
JP2020053876A (en) * 2018-09-27 2020-04-02 京セラ株式会社 Acoustic wave device, demultiplexer, and communication device

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024029360A1 (en) * 2022-08-04 2024-02-08 株式会社村田製作所 Elastic wave device and filter device

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