WO2021241364A1 - 弾性波装置 - Google Patents
弾性波装置 Download PDFInfo
- Publication number
- WO2021241364A1 WO2021241364A1 PCT/JP2021/019015 JP2021019015W WO2021241364A1 WO 2021241364 A1 WO2021241364 A1 WO 2021241364A1 JP 2021019015 W JP2021019015 W JP 2021019015W WO 2021241364 A1 WO2021241364 A1 WO 2021241364A1
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- WIPO (PCT)
- Prior art keywords
- electrode
- elastic wave
- mass
- electrode fingers
- film
- Prior art date
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- 239000000758 substrate Substances 0.000 claims abstract description 69
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- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 6
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- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 description 5
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- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 229910052799 carbon Inorganic materials 0.000 description 3
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- 239000010432 diamond Substances 0.000 description 3
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 3
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- HCWCAKKEBCNQJP-UHFFFAOYSA-N magnesium orthosilicate Chemical compound [Mg+2].[Mg+2].[O-][Si]([O-])([O-])[O-] HCWCAKKEBCNQJP-UHFFFAOYSA-N 0.000 description 3
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- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 3
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 3
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- 238000010897 surface acoustic wave method Methods 0.000 description 2
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- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
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- 239000003989 dielectric material Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- BPUBBGLMJRNUCC-UHFFFAOYSA-N oxygen(2-);tantalum(5+) Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[Ta+5].[Ta+5] BPUBBGLMJRNUCC-UHFFFAOYSA-N 0.000 description 1
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Images
Classifications
-
- 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
- H03H9/14538—Formation
- H03H9/14541—Multilayer finger or busbar electrode
-
- 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
-
- 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
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
- H03H9/02574—Characteristics of substrate, e.g. cutting angles of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic 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
- H03H9/14544—Transducers of particular shape or position
- H03H9/1457—Transducers having different finger widths
-
- 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
- H03H9/14544—Transducers of particular shape or position
- H03H9/14576—Transducers whereby only the last fingers have different characteristics with respect to the other fingers, e.g. different shape, thickness or material, split finger
- H03H9/14582—Transducers whereby only the last fingers have different characteristics with respect to the other fingers, e.g. different shape, thickness or material, split finger the last fingers having a different pitch
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/64—Filters using surface acoustic waves
- H03H9/6423—Means for obtaining a particular transfer characteristic
- H03H9/643—Means for obtaining a particular transfer characteristic the transfer characteristic being determined by reflective or coupling array characteristics
Definitions
- the present invention relates to an elastic wave device.
- Patent Document 1 describes an example of a surface acoustic wave resonator.
- a plurality of IDT (Interdigital Transducer) electrodes are provided on the piezoelectric substrate.
- the plurality of IDT electrodes are arranged along the elastic wave propagation direction.
- the electrode finger pitch of a part of each IDT electrode is different from the electrode finger pitch of another part.
- the IDT electrode has a central region and a pair of edge regions.
- the pair of edge regions are arranged so as to sandwich the central region in the direction in which the electrode fingers extend.
- a mass addition film is provided on the IDT electrode.
- the mass-added film extends along the elastic wave propagation direction. As a result, the transverse mode using the piston mode is suppressed.
- An object of the present invention is to provide an elastic wave device capable of effectively suppressing the transverse mode.
- a piezoelectric substrate and a pair of bus bars and a plurality of electrode fingers are provided on the piezoelectric substrate and are arranged in the elastic wave propagation direction, respectively.
- the IDT electrode comprises a plurality of IDT electrodes having a The portion where the adjacent electrode fingers overlap in the elastic wave propagation direction is a crossing region, and the crossing region is a central region located on the central side in the direction in which the plurality of electrode fingers extend, and the central region.
- the plurality of electrode fingers are arranged on both sides in the extending direction, and include a pair of edge regions including the tips of the plurality of electrode fingers, respectively, and in each of the IDT electrodes, the crossed region and the pair.
- a pair of gap regions are arranged between the two and the bus bar, and a plurality of mass-adding films provided so as to overlap with the portions of the plurality of electrode fingers located in the pair of edge regions in a plan view.
- the plurality of mass addition films include a plurality of first mass addition films arranged in the first pitch portion and a plurality of second mass addition films arranged in the second pitch portion.
- the first mass-adding film includes a film, and the first mass-adding film is provided so as to overlap with at least one of the electrode fingers in a plan view, and each of the second mass-adding films is one in a plan view. It is provided so as to overlap the electrode finger and not to overlap the electrode finger adjacent to the electrode finger, and the length of the first mass addition film along the elastic wave propagation direction is the length of the second mass addition film. It is longer than the length along the elastic wave propagation direction.
- a piezoelectric substrate and a pair of bus bars and a plurality of electrodes are provided on the piezoelectric substrate and are arranged in the elastic wave propagation direction, respectively.
- a plurality of IDT electrodes having a finger are provided, and at least one of the IDT electrodes has a first pitch portion having a relatively wide electrode finger pitch and a second pitch portion having a relatively narrow electrode finger pitch.
- the portion where the adjacent electrode fingers overlap in the elastic wave propagation direction is the crossing region, and the crossing region is a central region located on the central side in the direction in which the plurality of electrode fingers extend, and the center.
- a pair of edge regions that are arranged on both sides of the region in the direction in which the plurality of electrode fingers extend and include the tips of the plurality of electrode fingers, respectively, and in each IDT electrode, the crossed region and the crossed region.
- a pair of gap regions are arranged between the pair of bus bars, and the width of the plurality of electrode fingers in the first pitch portion in the pair of edge regions is wider than the width in the central region.
- the width of the plurality of electrode fingers in the second pitch portion in the pair of edge regions is equal to or less than the width in the central region, and the plurality of electrode fingers in the first pitch portion and the second pitch portion.
- each of the mass-adding films is formed with the plurality of electrode fingers and the plurality of electrode fingers in plan view. , It is provided so as to overlap the portion located between the plurality of electrode fingers.
- the transverse mode can be effectively suppressed.
- FIG. 1 is a plan view of an elastic wave device according to a first embodiment of the present invention.
- FIG. 2 is a front sectional view showing a part of the elastic wave device according to the first embodiment of the present invention.
- FIG. 3 is a plan view showing a part of the elastic wave device according to the first modification of the first embodiment of the present invention.
- FIG. 4 is a plan view showing a part of the elastic wave device according to the second modification of the first embodiment of the present invention.
- FIG. 5 is a plan view showing a part of the elastic wave device according to the third modification of the first embodiment of the present invention.
- FIG. 6 is a plan view of the elastic wave device according to the fourth 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 a front sectional view showing a part of the elastic wave device according to the first embodiment of the present invention.
- FIG. 3 is a plan view showing a part
- FIG. 7 is a plan view showing a part of the elastic wave device according to the second embodiment of the present invention.
- FIG. 8 is a plan view of the elastic wave device according to the third embodiment of the present invention.
- FIG. 9 is a plan view showing a part of the elastic wave device according to the third embodiment of the present invention.
- FIG. 10 is a front sectional view showing a part of the elastic wave device according to the third embodiment of the present invention.
- FIG. 11 is a cross-sectional view showing a part of a cross section of the elastic wave device according to the fourth embodiment of the present invention along the second direction.
- FIG. 12 is a plan view showing a part of the elastic wave device according to the fifth 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.
- the elastic wave device 1 of the present embodiment is a longitudinally coupled resonator type elastic wave filter.
- the elastic wave device 1 has a piezoelectric substrate 2.
- a plurality of IDT electrodes are provided on the piezoelectric substrate 2. More specifically, the IDT electrode 3A, the IDT electrode 3B, and the IDT electrode 3C are provided on the piezoelectric substrate 2. As described above, the elastic wave device 1 has three IDT electrodes. However, the number of IDT electrodes is not limited to the above.
- the IDT electrode 3A has a pair of bus bars and a plurality of electrode fingers. More specifically, the IDT electrode 3A has a first bus bar 4, a second bus bar 5, a plurality of first electrode fingers 6 and a plurality of second electrode fingers 7.
- the first bus bar 4 and the second bus bar 5 face each other.
- One end of each of the plurality of first electrode fingers 6 is connected to the first bus bar 4.
- One end of each of the plurality of second electrode fingers 7 is connected to the second bus bar 5.
- the plurality of first electrode fingers 6 and the plurality of second electrode fingers 7 are interleaved with each other.
- the first electrode finger 6 or the second electrode finger 7 may be simply referred to as an electrode finger.
- the IDT electrode 3B and the IDT electrode 3C also have a pair of bus bars and a plurality of electrode fingers, respectively.
- Elastic waves are excited by applying an AC voltage to the IDT electrode 3A.
- the plurality of IDT electrodes are arranged in the elastic wave propagation direction. More specifically, the IDT electrode 3B is arranged between the IDT electrode 3A and the IDT electrode 3C.
- the elastic wave propagation direction is defined as the first direction x
- the direction in which the plurality of electrode fingers extend is defined as the second direction y.
- the first direction x and the second direction y are orthogonal to each other.
- a pair of reflectors 8A and 8Bs are provided on both sides of the plurality of IDT electrodes in the first direction x on the piezoelectric substrate 2. More specifically, the reflector 8A and the reflector 8B are arranged so as to sandwich the IDT electrode 3A, the IDT electrode 3B, and the IDT electrode 3C.
- the reflector 8A is adjacent to the IDT electrode 3A, and the reflector 8B is adjacent to the IDT electrode 3C.
- the IDT electrode 3A, the IDT electrode 3B and the IDT electrode 3C, and the reflector 8A and the reflector 8B may be made of a single-layer metal film or may be made of a laminated metal film.
- the IDT electrode 3B includes a first pitch portion E and a second pitch portion F.
- the electrode finger pitch is relatively wide.
- the electrode finger pitch is relatively narrow.
- the electrode finger pitch is the distance between the centers of adjacent electrode fingers.
- one first pitch portion E and two second pitch portions F are arranged. More specifically, the first pitch portion E is located at the center of the IDT electrode 3B in the first direction x.
- the pair of second pitch portions F are located on both sides of the first pitch portion E in the first direction x.
- the second pitch portion F is located on the IDT electrode 3B side.
- the other portion of the IDT electrode 3A is configured as a first pitch portion E.
- the second pitch portion F is located on the IDT electrode 3B side.
- the other portion of the IDT electrode 3C is configured as a first pitch portion E. Since each IDT electrode has a first pitch portion E and a second pitch portion F, the steepness in the filter characteristics can be enhanced. In the present specification, high steepness means that the amount of change in frequency is small with respect to the amount of change in a certain amount of attenuation in the vicinity of the end of the pass band.
- the arrangement of the first pitch portion E and the second pitch portion F in each IDT electrode is not limited to the above. At least one of the plurality of IDT electrodes may have a first pitch portion E and a second pitch portion F.
- the width of the electrode finger in the first pitch portion E and the width of the electrode finger in the second pitch portion F are the same.
- the width of the electrode finger is a dimension along the first direction x of the electrode finger.
- the width of each electrode finger is constant in the second direction y.
- the width of the electrode finger in the second pitch portion F may be narrower than the width of the electrode finger in the first pitch portion E.
- the portion where the adjacent electrode fingers overlap in the first direction x is the crossing region A.
- the crossing region A includes a central region B and a pair of edge regions.
- the central region B is located on the central side in the second direction y.
- the pair of edge regions are specifically the first edge region Ca and the second edge region Cb.
- the first edge region Ca and the second edge region Cb are arranged on both sides of the central region B in the second direction y.
- the first edge region Ca is located on the first bus bar 4 side.
- the second edge region Cb is located on the second bus bar 5 side.
- the central regions B of all IDT electrodes overlap when viewed from the first direction x.
- the first edge regions Ca of all IDT electrodes overlap.
- the second edge regions Cb of all the IDT electrodes overlap.
- a plurality of mass addition films are provided so as to overlap with the portions located in the first edge region Ca and the second edge region Cb of the plurality of electrode fingers in a plan view. More specifically, a plurality of mass addition films are provided on the IDT electrode 3A, the IDT electrode 3B, and the IDT electrode 3C, respectively.
- the plurality of mass-added films are provided in the first mass-added film 9a provided in each of the first edge region Ca and the second edge region Cb, and in each of the first edge region Ca and the second edge region Cb.
- the provided second mass addition film 9b is included.
- the plurality of mass addition films include the plurality of first mass addition films 9a and the plurality of second mass addition films 9b.
- the first mass addition film 9a has a band shape and is arranged in the first pitch portion E.
- Each first mass addition film 9a is provided over a plurality of electrode fingers. More specifically, the first mass addition film 9a is provided not only on the plurality of electrode fingers but also on the portion of the piezoelectric substrate 2 located between the plurality of electrode fingers.
- the second mass addition film 9b is arranged in the second pitch portion F.
- Each second mass addition film 9b is provided on one electrode finger.
- the second mass addition film 9b is not arranged between the electrode fingers.
- the dimension along the first direction x of the mass-adding film is defined as the length of the mass-adding film.
- the length of the first mass-adding film 9a is longer than the length of the second mass-adding film 9b.
- the first mass addition film 9a and the second mass addition film 9b may be a metal film or a dielectric film.
- the feature of this embodiment is that it has the following configuration. 1) At least one IDT electrode has a first pitch portion E and a second pitch portion F. 2) A band-shaped first mass-adding film 9a is arranged on the first pitch portion E. 3) The second mass addition film 9b is arranged on the second pitch portion F. 4) The length of the first mass-adding film 9a is longer than the length of the second mass-adding film 9b. 5) The first mass addition film 9a and the second mass addition film 9b overlap with the portions located in the first edge region Ca and the second edge region Cb of the electrode finger in a plan view. By them, the transverse mode can be effectively suppressed. The details will be described below.
- a first mass addition film 9a and a second mass addition film 9b are provided in the first edge region Ca. Therefore, the speed of sound in the first edge region Ca becomes low. As a result, a low sound velocity region is formed in the first edge region Ca.
- the low sound velocity region is a region in which the speed of sound in the region is lower than the speed of sound in the central region B.
- a low sound velocity region is also configured in the second edge region Cb.
- the first edge region Ca and the second edge region Cb are arranged outside the central region B in the second direction y. That is, the low sound velocity region is arranged outside the central region B in the second direction y. Thereby, the transverse mode can be suppressed.
- the present inventor has found that the conditions for suppressing the transverse mode are different between the first pitch portion and the second pitch portion. For example, it is assumed that the width of each electrode finger of the IDT electrode is constant in the second direction, and the same mass addition film is provided in the first pitch portion and the second pitch portion. In this case, it is difficult to sufficiently satisfy the conditions for suppressing the transverse mode in both the first pitch portion and the second pitch portion. Therefore, it is difficult to sufficiently suppress the transverse mode.
- the band-shaped first mass-adding film 9a is arranged on the first pitch portion E, and the second mass-adding film 9b is arranged on the second pitch portion F. ing.
- the condition for suppressing the transverse mode can be suitably satisfied. Therefore, the transverse mode can be effectively suppressed as the elastic wave device 1 as a whole.
- the IDT electrode 3A, the IDT electrode 3B, and the IDT electrode 3C each have a pair of gap regions.
- a pair of gap regions are arranged between the crossover region A and the pair of bus bars in each IDT electrode.
- the pair of gap regions are a first gap region Da and a second gap region Db.
- the first gap region Da is located between the first bus bar 4 and the plurality of second electrode fingers 7.
- the high sound velocity region is formed in the first gap region Da.
- the high sound velocity region is a region in which the speed of sound in the region is higher than the speed of sound in the central region B.
- the second gap region Db is located between the second bus bar 5 and the plurality of first electrode fingers 6.
- the second gap region Db only the second electrode finger 7 out of the first electrode finger 6 and the second electrode finger 7 is arranged.
- a high sound velocity region is formed in the second gap region Db.
- V3 When the speed of sound in the high sound velocity region is V3, V1 ⁇ V3.
- the relationship between the sound speeds in the low sound speed region, the central region B, and the high sound speed region is V2 ⁇ V1 ⁇ V3.
- the relationship between the speeds of sound as described above is shown in FIG. In the portion showing the relationship between the speeds of sound in FIG. 1, as shown by the arrow V, the higher the sound velocity is, the higher the line indicating the height of each sound velocity is located on the left side.
- the low sound velocity region is arranged outside the central region B and the high sound velocity region is arranged outside the low sound velocity region in the second direction y. .. Thereby, the transverse mode can be suppressed effectively and more reliably.
- the dimension along the second direction y of the mass-added film is defined as the width of the mass-added film.
- the dimension along the second direction y of the low sound velocity region is defined as the width of the low sound velocity region.
- the width of the first mass addition film 9a and the width of the second mass addition film 9b are the same. As a result, there is no discontinuity in the width of the low sound velocity region. Therefore, deterioration of insertion loss can be suppressed.
- the width of the first mass-adding film 9a and the width of the second mass-adding film 9b may be different.
- one first mass addition film 9a is provided in the first edge region Ca for each first pitch portion E at one location.
- a plurality of first mass addition films 9a may be provided in the first edge region Ca for each of the first pitch portions E at one location.
- each of the first mass addition films 9a may be provided so as to reach the two electrode fingers.
- a different first mass addition film 9a is arranged for each of the two electrode fingers.
- one first mass addition film 9a is provided in the second edge region Cb for each first pitch portion E at one location.
- a plurality of first mass addition films 9a may be provided in the second edge region Cb for each of the first pitch portions E at one location.
- Each second mass addition film 9b is not provided between the electrode fingers. However, the second mass addition film 9b may reach the portion between the electrode fingers on the piezoelectric substrate 2. Each second mass addition film 9b may be provided so as to overlap one electrode finger and not to overlap the electrode finger adjacent to the electrode finger in a plan view.
- FIG. 2 is a front sectional view showing a part of the elastic wave device according to the first embodiment. Note that FIG. 2 shows a cross section of the portion where the IDT electrode 3B is provided in the central region B.
- the piezoelectric substrate 2 is a laminated substrate including the piezoelectric layer 16. More specifically, in the piezoelectric substrate 2, the support substrate 13, the hypersonic film 14 as the hypersonic material layer, the low sound velocity film 15, and the piezoelectric layer 16 are laminated in this order.
- the IDT electrode 3A, IDT electrode 3B, IDT electrode 3C, reflector 8A, and reflector 8B are provided on the piezoelectric layer 16.
- the piezoelectric layer 16 is a lithium tantalate layer.
- the material of the piezoelectric layer 16 is not limited to the above, and for example, lithium niobate or the like can be used.
- ⁇ be the wavelength defined by the average value of the electrode finger pitches of the IDT electrodes.
- the thickness of the piezoelectric layer 16 is 1 ⁇ or less.
- the thickness of the piezoelectric layer 16 is not limited to the above.
- the low sound velocity film 15 is a relatively low sound velocity film. More specifically, the speed of sound of the bulk wave propagating in the low-pitched sound film 15 is lower than the speed of sound of the bulk wave propagating in the piezoelectric layer 16.
- the low sound velocity film 15 is a silicon oxide film. Silicon oxide can be represented by SiO x.
- the bass velocity film 15 is a SiO 2 film.
- the material of the bass velocity film 15 is not limited to the above, and for example, a material containing glass, silicon nitride, tantalum oxide, or a compound obtained by adding fluorine, carbon, or boron to silicon oxide may be used. can.
- the hypersonic material layer is a relatively hypersonic layer. More specifically, the sound velocity of the bulk wave propagating in the hypersonic material layer is higher than the sound velocity of the elastic wave propagating in the piezoelectric layer 16.
- the hypersonic film 14 as the hypersonic material layer is a silicon nitride film.
- the material of the high-pitched sound film 14 is not limited to the above, and for example, silicon, aluminum oxide, silicon carbide, silicon nitride, sapphire, lithium tantalate, lithium niobate, crystal, alumina, zirconia, cordierite, mulite, and the like.
- a medium containing the above materials as a main component such as steatite, forsterite, magnesia, a DLC (diamond-like carbon) film, or diamond, can also be used.
- the support substrate 13 is a silicon substrate.
- the material of the support substrate 13 is not limited to the above, and for example, piezoelectric materials such as aluminum oxide, lithium tantalate, lithium niobate, and crystal, alumina, magnesia, silicon nitride, aluminum nitride, silicon carbide, zirconia, and cordierite.
- Various ceramics such as mulite, steatite and forsterite, dielectrics such as sapphire, diamond and glass, semiconductors or resins such as gallium nitride can also be used.
- the piezoelectric substrate 2 In the piezoelectric substrate 2, the hypersonic film 14, the low sound velocity film 15, and the piezoelectric layer 16 are laminated in this order. Since the piezoelectric substrate 2 has such a laminated structure, the Q value can be increased, and the energy of elastic waves can be effectively confined to the piezoelectric layer 16 side.
- the laminated structure of the piezoelectric substrate 2 is not limited to the above.
- the piezoelectric substrate 2 does not have to have the bass velocity film 15.
- the piezoelectric substrate 2 may be a three-layer laminated substrate.
- the support substrate 13, the hypersonic film 14, and the piezoelectric layer 16 may be laminated in this order.
- the hypersonic material layer may be a hypersonic support substrate.
- the piezoelectric substrate 2 may be a three-layer laminated substrate. Specifically, in the piezoelectric substrate 2, the hypersonic support substrate, the low sound velocity film 15, and the piezoelectric layer 16 may be laminated in this order.
- the piezoelectric substrate 2 may be a two-layer laminated substrate. Specifically, in the piezoelectric substrate 2, the hypersonic support substrate and the piezoelectric layer 16 may be laminated in this order. Even in these cases, the Q value can be increased.
- the piezoelectric substrate 2 may be a piezoelectric substrate composed of only the piezoelectric layer 16.
- Examples of the material of the high-pitched sound support substrate include silicon, aluminum oxide, silicon carbide, silicon nitride, silicon nitride, sapphire, lithium tantalate, lithium niobate, crystal, alumina, zirconia, cordierite, mulite, and steatite.
- a medium containing the above materials as a main component such as forsterite, magnesia, DLC (diamond-like carbon) film, or diamond, can be used.
- a mass addition film 9c is provided on the reflector 8A and the reflector 8B, respectively.
- the mass-added film 9c is strip-shaped like the first mass-added film 9a.
- the mass addition film 9c may not be provided on the reflector 8A and the reflector 8B.
- the elastic wave device 1 is a longitudinally coupled resonator type elastic wave filter.
- the present invention is not limited to this, and the elastic wave device 1 may be a transversal type filter device or the like. In this case, the reflector 8A and the reflector 8B may not be provided.
- first modification and a second modification of the first embodiment will be shown.
- the shape of the electrode finger in the first pitch portion E or the second pitch portion F of the IDT electrode 3A, the IDT electrode 3B and the IDT electrode 3C is the first embodiment. Is different. Also in the first modification and the second modification, the transverse mode can be effectively suppressed as in the first embodiment.
- the shape of the electrode finger in the second pitch portion F is different from that of the first embodiment.
- the width of the plurality of electrode fingers in the second pitch portion F in the first edge region Ca and the second edge region Cb is equal to or less than the width in the central region B. More specifically, the width of the portion including the tip portions of the plurality of electrode fingers in the second pitch portion F is equal to or smaller than the width in the central region B.
- the tip of the second electrode finger 27 is included in the first edge region Ca. In the first edge region Ca, the width of the second electrode finger 27 becomes narrower from the central region B side to the tip end side. Therefore, the width of the tip of the second electrode finger 27 is narrower than the width of the second electrode finger 27 in the central region B.
- the width of the second electrode finger 27 in the first edge region Ca is equal to or smaller than the width of the second electrode finger 27 in the central region B.
- the width of the first electrode finger 26 in the first edge region Ca is the same as the width of the first electrode finger 26 in the central region B.
- the width of the electrode finger is a dimension along the first direction x of the electrode finger.
- the tip of the first electrode finger 26 is included in the second edge region Cb.
- the width of the first electrode finger 26 is narrowed from the central region B side to the tip end side. Therefore, the width of the tip of the first electrode finger 26 is narrower than the width of the first electrode finger 26 in the central region B.
- the width of the first electrode finger 26 in the second edge region Cb is equal to or smaller than the width of the electrode finger in the central region B.
- the width of the second electrode finger 27 in the second edge region Cb is the same as the width of the second electrode finger 27 in the central region B.
- the widths of the plurality of electrode fingers in the first pitch portion E in the first edge region Ca and the second edge region Cb are the same as the widths in the central region B.
- the width of a part of the plurality of electrode fingers in the first pitch portion E in the first edge region Ca or the second edge region Cb may be narrower than the width in the central region B.
- the width of the second electrode finger 7 in the first edge region Ca may be equal to or less than the width of the second electrode finger 7 in the central region B.
- the width of the second electrode finger 7 in the first pitch portion E may be narrowed from the central region B side to the tip side in the first edge region Ca.
- the width of the first electrode finger 6 in the second edge region Cb may be equal to or less than the width of the first electrode finger 6 in the central region B.
- the width of the first electrode finger 6 in the first pitch portion E may be narrowed from the central region B side to the tip side in the second edge region Cb.
- the shape of the second mass addition film 29b is different from that of the first embodiment. More specifically, in the first embodiment, the shape of the second mass addition film 9b is rectangular. On the other hand, in this modification, the shape of the second mass addition film 29b is substantially elliptical. In the second pitch portion F, when the width of the second electrode finger 27 in the first edge region Ca is equal to or less than the width of the second electrode finger 27 in the central region B, the second electrode finger 27 is provided.
- the obtained second mass addition film 29b may have a rounded shape as in the present modification.
- the first electrode finger 36 in the first pitch portion E has a wide portion 36a and a wide portion 36b.
- the wide portion 36a and the wide portion 36b are portions where the width of the electrode fingers is wider than the other portions.
- the wide portion 36a is located in the first edge region Ca.
- the wide portion 36b is located in the second edge region Cb.
- the second electrode finger 37 in the first pitch portion E has a wide portion 37a and a wide portion 37b.
- the wide portion 37a is located in the first edge region Ca.
- the wide portion 37b is located in the second edge region Cb.
- all the first electrode fingers 36 in the first pitch portion E have a wide portion 36a and a wide portion 36b.
- All the second electrode fingers 37 in the first pitch portion E have a wide portion 37a and a wide portion 37b.
- the first pitch portion E may include a first electrode finger 26 having no wide portion 36a or wide portion 36b.
- the first pitch portion E may include a second electrode finger 27 having no wide portion 37a or wide portion 37b.
- the electrode finger pitch is narrow in the second pitch portion F. Therefore, when the plurality of electrode fingers in the second pitch portion F have wide portions, the surge resistance may deteriorate. On the other hand, in this modification, the plurality of electrode fingers in the second pitch portion F do not have a wide portion. Therefore, the surge resistance is unlikely to deteriorate.
- the thickness of the first mass-adding film 9a is preferably thicker than the thickness of the second mass-adding film 9b. In this case, it is easier to adjust the first pitch portion E and the second pitch portion F to the optimum conditions for suppressing the transverse mode. Therefore, the transverse mode can be suppressed more reliably.
- the first mass addition film 9a and the second mass addition film 9b are provided on the IDT electrode 3A, the IDT electrode 3B, and the IDT electrode 3C. More specifically, the first mass addition film 9a and the second mass addition film 9b are provided on the side of the plurality of electrode fingers opposite to the piezoelectric substrate 2 side. However, each of the second mass addition films 9b may overlap with one electrode finger in a plan view. In this case, the edge of each of the second mass addition films 9b may be provided inside the edge of the electrode finger in a plan view as in the second modification shown in FIG. Alternatively, the edge of each of the second mass addition films 9b may be provided so as to reach the edge of the electrode finger in a plan view as in the third modification shown in FIG.
- Each of the first mass addition films 9a may be overlapped with a plurality of electrode fingers in a plan view.
- the first mass addition film 9a and the second mass addition film 9b are provided between each IDT electrode and the piezoelectric substrate 2.
- a first mass addition film 9a and a second mass addition film 9b are provided between the plurality of electrode fingers and the piezoelectric substrate 2.
- a band-shaped mass addition film is also provided between the reflector 8A and the reflector 8B and the piezoelectric substrate 2.
- each mass addition film is shown by a broken line.
- the first mass addition film 9a is strip-shaped.
- the length of the first mass-adding film 9a may be longer than the length of the second mass-adding film 9b, and the first mass-adding film 9a does not have to be band-shaped.
- FIG. 7 is a plan view showing a part of the elastic wave device according to the second embodiment.
- This embodiment is different from the first embodiment in that the first mass addition film 49a is in the form of individual pieces. Each of the first mass addition films 49a is provided so as to overlap one electrode finger in a plan view. The first mass addition film 49a is not arranged between the electrode fingers.
- the elastic wave device of the second embodiment has the same configuration as the elastic wave device 1 of the first embodiment.
- both the first pitch portion E and the second pitch portion F can be set as suitable conditions for suppressing the transverse mode. Therefore, the transverse mode can be effectively suppressed.
- the first mass addition film 49a may reach the portion between the electrode fingers on the piezoelectric substrate 2.
- the two first mass addition films 49a may reach the portion between the same electrode fingers on the piezoelectric substrate 2.
- the first mass-adding film is arranged in the first pitch portion, and the second mass-adding film is arranged in the second pitch portion.
- An example is shown. In the following, an example in which the same mass-added film is arranged in the first pitch portion and the second pitch portion will be shown.
- FIG. 8 is a plan view of the elastic wave device according to the third embodiment.
- FIG. 9 is a plan view showing a part of the elastic wave device according to the third embodiment.
- one mass addition film 59 is provided so as to overlap the portion located in the first edge region Ca of the plurality of electrode fingers in a plan view.
- the mass addition film 59 is strip-shaped. More specifically, the mass addition film 59 is provided on both the plurality of electrode fingers and the portion located between the plurality of electrode fingers.
- the mass-added film 59 is provided between the IDT electrode 3A, the IDT electrode 3B, and the IDT electrode 3C, and the piezoelectric substrate 2. As described above, in the plan view, one mass addition film 59 overlaps with all the IDT electrodes in the elastic wave device 51.
- the mass-added film 59 overlaps both the electrode finger in the first pitch portion E and the electrode finger in the second pitch portion F in a plan view. Similarly, one mass addition film 59 is provided so as to overlap the portion located in the second edge region Cb of the plurality of electrode fingers in a plan view.
- the plurality of electrode fingers in the first pitch portion E have the same configuration as the second modification of the first embodiment shown in FIG. More specifically, all the first electrode fingers 36 in the first pitch portion E have the wide portion 36a and the wide portion 36b. All the second electrode fingers 37 in the first pitch portion E have a wide portion 37a and a wide portion 37b.
- the first pitch portion E may include a first electrode finger 26 having no wide portion 36a or wide portion 36b.
- the first pitch portion E may include a second electrode finger 27 having no wide portion 37a or wide portion 37b.
- the mass addition film 59 is provided between the IDT electrode 3A, the IDT electrode 3B, and the IDT electrode 3C, and the piezoelectric substrate 52.
- the mass addition film 59 may be provided on the IDT electrode 3A, the IDT electrode 3B, and the IDT electrode 3C.
- FIG. 10 is a front sectional view showing a part of the elastic wave device according to the third embodiment.
- the piezoelectric substrate 52 of the elastic wave device 51 is a piezoelectric substrate composed of only a piezoelectric layer. More specifically, the piezoelectric substrate 52 is a lithium niobate substrate. However, the material and layer structure of the piezoelectric substrate 52 are not limited to the above. For example, it may have the above-mentioned two-layer or three-layer structure, or may have the same layer structure as the first embodiment. Alternatively, the piezoelectric substrate 52 may be a lithium tantalate substrate or the like.
- the feature of this embodiment is that it has the following configuration. 1) At least one IDT electrode has a first pitch portion E and a second pitch portion F. 2) The width of the plurality of electrode fingers in the first pitch portion E in the first edge region Ca and the second edge region Cb is wider than the width in the central region B. 3) A band-shaped mass addition film 59 is arranged on the first pitch portion E and the second pitch portion F. 4) The mass addition film 59 overlaps with the portions located in the first edge region Ca and the second edge region Cb of the plurality of electrode fingers in a plan view.
- the shapes of the electrode fingers in the first edge region Ca and the second edge region Cb are different in the first pitch portion E and the second pitch portion F. More specifically, the plurality of electrode fingers in the second pitch portion F do not have a wide portion, and the plurality of electrode fingers in the first pitch portion E have a wide portion.
- the same mass addition film 59 is arranged in the first pitch portion E and the second pitch portion F.
- the width of the mass addition film 59 is constant, and the width of the low sound velocity region is also constant. Therefore, deterioration of insertion loss can be suppressed.
- the mass addition film 59 extends from between the reflector 8A and the piezoelectric substrate 2 to between the reflector 8B and the piezoelectric substrate 2. However, the mass addition film 59 does not have to overlap with the reflector 8A and the reflector 8B in a plan view.
- one mass addition film 59 is provided in each of the first edge region Ca and the second edge region Cb.
- Each mass addition film 59 overlaps all IDT electrodes in plan view.
- the mass addition film 59 may not be provided between the IDT electrodes.
- the plurality of mass addition films 59 overlap with the portion of the plurality of IDT electrodes located in the first edge region Ca in a plan view.
- the mass addition film 59 that overlaps the portion of the IDT electrode 3A located in the first edge region Ca in plan view and the portion of the IDT electrode 3B located in the first edge region Ca overlaps in plan view. It is not integrated with the mass addition film 59.
- the electrode finger in the second pitch portion F may be configured in the same manner as in the first modification of the first embodiment. More specifically, among the plurality of electrode fingers in the second pitch portion F, the tip of the electrode finger whose tip is included in the first edge region Ca or the second edge region Cb, in the edge region.
- the width of the portion including the portion may be equal to or less than the width in the central region B.
- FIG. 11 is a cross-sectional view showing a part of a cross section of the elastic wave device according to the fourth embodiment along the second direction. More specifically, FIG. 11 shows a part near the boundary between the central region B and the second edge region Cb, such as the first electrode finger 6.
- This embodiment is different from the first embodiment in that the protective film 64 is provided on the piezoelectric substrate 2. Except for the above points, the elastic wave device of the present embodiment has the same configuration as the elastic wave device 1 of the first embodiment.
- the protective film 64 covers the IDT electrode 3B and the plurality of first mass addition films 9a. Further, the protective film 64 also covers the IDT electrode 3A, the IDT electrode 3C, and the plurality of second mass addition films 9b, which are shown with reference to FIG. Each IDT electrode has a portion directly covered by the protective film 64 and a portion indirectly covered by the protective film 64 via each mass addition film. Since the protective film 64 is provided, each IDT electrode is not easily damaged.
- the first mass addition film 9a has a first main surface 19d, a second main surface 19e, and a side surface 19f.
- the first main surface 19d is in contact with the IDT electrode 3B.
- the second main surface 19e faces the first main surface 19d.
- the side surface 19f is connected to the first main surface 19d and the second main surface 19e.
- the side surface 19f is inclined with respect to the thickness direction of the first mass addition film 9a.
- the thickness direction of the first mass addition film 9a is the direction in which the first main surface 19d and the second main surface 19e face each other.
- the second mass-added film 9b which is shown with reference to FIG.
- the side surface of the second mass addition film 9b is also inclined with respect to the thickness direction of the second mass addition film 9b.
- the side surface of each mass addition film does not necessarily have to be inclined.
- the thickness of the portion covering the side surface 19f of each first mass-adding film 9a covers the second main surface 19e of each first mass-adding film 9a. It is thinner than the thickness of the portion and the thickness of the portion that directly covers each IDT electrode. Further, in the protective film 64, the thickness of the portion covering the side surface of each second mass addition film 9b is the thickness of the portion covering the second main surface of each second mass addition film 9b, and each. It is thinner than the thickness of the part that directly covers the IDT electrode.
- the change in sound velocity near the boundary between the central region B and the second edge region Cb is steep.
- the slope of the change in the speed of sound with respect to the distance in the second direction y can be increased.
- the change in the speed of sound near the boundary between the central region B and the first edge region Ca can be steep. Therefore, the transverse mode can be effectively suppressed.
- FIG. 12 is a plan view showing a part of the elastic wave device according to the fifth embodiment.
- each of the first bus bar 74 and the second bus bar 75 of each IDT electrode is provided with a plurality of openings along the first direction x. different. Except for the above points, the elastic wave device of the present embodiment has the same configuration as that of the first embodiment.
- the first bus bar 74 has a first opening forming region Ga.
- a plurality of openings 74d are provided in the first opening forming region Ga.
- the first bus bar 74 has an inner bus bar portion 74a and an outer bus bar portion 74c, and a plurality of connection electrodes 74b.
- the first opening forming region Ga is located between the inner bus bar portion 74a and the outer bus bar portion 74c in the second direction y.
- the inner bus bar portion 74a is located on the crossing region A side.
- the inner bus bar portion 74a and the outer bus bar portion 74c are connected by a plurality of connection electrodes 74b.
- the plurality of openings 74d are openings surrounded by an inner bus bar portion 74a, an outer bus bar portion 74c, and a plurality of connection electrodes 74b.
- the second bus bar 75 has a second opening forming region Gb.
- a plurality of openings 75d are provided in the second opening forming region Gb.
- the second bus bar 75 has an inner bus bar portion 75a and an outer bus bar portion 75c, and a plurality of connection electrodes 75b.
- the plurality of openings 75d are openings surrounded by an inner bus bar portion 75a, an outer bus bar portion 75c, and a plurality of connection electrodes 75b.
- a high sound velocity region is configured in the first opening forming region Ga and the second opening forming region Gb.
- the first mass-adding film 9a is arranged in the first pitch portion E, and the second mass-adding film 9b is arranged in the second pitch portion F. Have been placed. Therefore, the transverse mode can be effectively suppressed.
- Elastic wave device 2 Piezoelectric substrate 3A, 3B, 3C ... IDT electrode 4 ... First bus bar 5 ... Second bus bar 6, 7 ... First, second electrode fingers 8A, 8B ... Reflector 9a, 9b ... 1st and 2nd mass addition film 9c ... Mass addition film 13 ... Support substrate 14 ... High sound velocity film 15 ... Low sound velocity film 16 ... Piezoelectric layer 19d, 19e ... First and second main surfaces 19f ... Side surfaces 26, 27 ... First and second electrode fingers 29b ... Second mass addition film 36, 37 ... First and second electrode fingers 36a, 36b, 37a, 37b ... Wide portion 49a ... First mass addition film 51 ... Piezoelectric wave device 52 ...
- Piezoelectric substrate 59 Mass addition film 64 ... Protective film 74, 75 ... First and second bus bars 74a, 75a ... Inner bus bar portions 74b, 75b ... Connection electrodes 74c, 75c ... Outer bus bar portion 74d, 75d ... Opening A ... Crossing region B ... Central region Ca, Cb ... First and second edge regions Da, Db ... First and second gap regions E, F ... First and second pitch portions Ga, Gb ... First and second opening forming regions
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Abstract
Description
2…圧電性基板
3A,3B,3C…IDT電極
4…第1のバスバー
5…第2のバスバー
6,7…第1,第2の電極指
8A,8B…反射器
9a,9b…第1,第2の質量付加膜
9c…質量付加膜
13…支持基板
14…高音速膜
15…低音速膜
16…圧電体層
19d,19e…第1,第2の主面
19f…側面
26,27…第1,第2の電極指
29b…第2の質量付加膜
36,37…第1,第2の電極指
36a,36b,37a,37b…幅広部
49a…第1の質量付加膜
51…弾性波装置
52…圧電性基板
59…質量付加膜
64…保護膜
74,75…第1,第2のバスバー
74a,75a…内側バスバー部
74b,75b…接続電極
74c,75c…外側バスバー部
74d,75d…開口部
A…交叉領域
B…中央領域
Ca,Cb…第1,第2のエッジ領域
Da,Db…第1,第2のギャップ領域
E,F…第1,第2のピッチ部
Ga,Gb…第1,第2の開口部形成領域
Claims (13)
- 圧電性基板と、
前記圧電性基板上に設けられており、弾性波伝搬方向に並んでおり、かつそれぞれ、一対のバスバーと、複数の電極指と、を有する複数のIDT電極と、
を備え、
少なくとも1つの前記IDT電極が、電極指ピッチが相対的に広い第1のピッチ部と、電極指ピッチが相対的に狭い第2のピッチ部と、を含み、
隣り合う前記電極指が弾性波伝搬方向において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、前記複数の電極指が延びる方向における中央側に位置している中央領域と、前記中央領域の前記複数の電極指が延びる方向における両側に配置されており、かつ前記複数の電極指の先端部をそれぞれ含む一対のエッジ領域と、を含み、
各前記IDT電極において、前記交叉領域と、前記一対のバスバーとの間に、一対のギャップ領域が配置されており、
前記複数の電極指の前記一対のエッジ領域に位置する部分と、平面視において重なるように設けられている複数の質量付加膜をさらに備え、
前記複数の質量付加膜が、前記第1のピッチ部に配置されている複数の第1の質量付加膜と、前記第2のピッチ部に配置されている複数の第2の質量付加膜と、を含み、
前記第1の質量付加膜が、平面視において、少なくとも1つの前記電極指と重なるように設けられており、
それぞれの前記第2の質量付加膜が、平面視において、1つの前記電極指と重なり、該電極指と隣接する電極指と重ならないように設けられており、
前記第1の質量付加膜の弾性波伝搬方向に沿う長さが、前記第2の質量付加膜の弾性波伝搬方向に沿う長さよりも長い、弾性波装置。 - 前記第2のピッチ部における前記複数の電極指の、前記一対のエッジ領域における幅が前記中央領域における幅以下である、請求項1に記載の弾性波装置。
- それぞれの前記第1の質量付加膜が、平面視において、前記第1のピッチ部における前記複数の電極指、及び、前記複数の電極指間に位置する部分と重なるように設けられている、請求項1または2に記載の弾性波装置。
- それぞれの前記第1の質量付加膜が、平面視において、1つの前記電極指と重なり、該電極指と隣接する電極指と重ならないように設けられている、請求項1または2に記載の弾性波装置。
- 前記第1の質量付加膜の前記複数の電極指が延びる方向に沿う長さと、前記第2の質量付加膜の前記複数の電極指が延びる方向に沿う長さとが同じである、請求項1~4のいずれか1項に記載の弾性波装置。
- 圧電性基板と、
前記圧電性基板上に設けられており、弾性波伝搬方向に並んでおり、かつそれぞれ、一対のバスバーと、複数の電極指と、を有する複数のIDT電極と、
を備え、
少なくとも1つの前記IDT電極が、電極指ピッチが相対的に広い第1のピッチ部と、電極指ピッチが相対的に狭い第2のピッチ部と、を含み、
隣り合う前記電極指が弾性波伝搬方向において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、前記複数の電極指が延びる方向における中央側に位置している中央領域と、前記中央領域の前記複数の電極指が延びる方向における両側に配置されており、かつ前記複数の電極指の先端部をそれぞれ含む一対のエッジ領域と、を含み、
各前記IDT電極において、前記交叉領域と、前記一対のバスバーとの間に、一対のギャップ領域が配置されており、
前記第1のピッチ部における前記複数の電極指の、前記一対のエッジ領域における幅が前記中央領域における幅よりも広く、
前記第2のピッチ部における前記複数の電極指の、前記一対のエッジ領域における幅が前記中央領域における幅以下であり、
前記第1のピッチ部及び前記第2のピッチ部における前記複数の電極指の、前記一対のエッジ領域に位置する部分と、平面視において重なるように設けられている複数の質量付加膜をさらに備え、
それぞれの前記質量付加膜が、平面視において、前記複数の電極指、及び、前記複数の電極指間に位置する部分と重なるように設けられている、弾性波装置。 - それぞれの前記質量付加膜が、平面視において、全ての前記IDT電極と重なっている、請求項6に記載の弾性波装置。
- 前記複数の電極指の前記圧電性基板側とは反対側に前記複数の質量付加膜が設けられている、請求項1~7のいずれか1項に記載の弾性波装置。
- 前記複数の質量付加膜がそれぞれ、前記IDT電極に接触している第1の主面と、前記第1の主面と対向している第2の主面と、前記第1の主面及び前記第2の主面に接続されている側面と、を有し、前記側面が前記質量付加膜の厚み方向に対して傾斜しており、
前記IDT電極及び前記複数の質量付加膜を覆うように、前記圧電性基板上に設けられている保護膜をさらに備え、
前記保護膜において、前記質量付加膜の前記側面を覆っている部分の厚みが、前記質量付加膜の前記第2の主面を覆っている部分の厚み、及び前記IDT電極を直接的に覆っている部分の厚みよりも薄い、請求項8に記載の弾性波装置。 - 前記複数の電極指と前記圧電性基板との間に前記複数の質量付加膜が設けられている、請求項1~7のいずれか1項に記載の弾性波装置。
- 前記IDT電極の前記一対のバスバーにそれぞれ、弾性波伝搬方向に沿って複数の開口部が設けられている、請求項1~10のいずれか1項に記載の弾性波装置。
- 前記圧電性基板は、支持基板と、高音速膜と、低音速膜と、圧電体層とが、この順序において積層された積層基板であり、
前記低音速膜を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く、
前記高音速膜を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、請求項1~11のいずれか1項に記載の弾性波装置。 - 前記圧電性基板上における前記複数のIDT電極の弾性波伝搬方向両側に設けられている反射器をさらに備える、縦結合共振子型弾性波フィルタである、請求項1~12のいずれか1項に記載の弾性波装置。
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