Elastic wave device and module including the elastic wave device

Abstract

To provide an elastic wave device capable of suppressing a lateral-mode spurious more surely.SOLUTION: In an elastic wave device, at least one of a plurality of sets of IDT electrodes includes a first bus bar, a second bus bar, a plurality of first electrode fingers, a plurality of second electrode fingers, a plurality of first dummy electrodes, and a plurality of second dummy electrodes. A tip part of the first electrode fingers includes a first tip side wide region. A tip part of the second electrode fingers includes a second tip side wide region. The length of the first dummy electrodes continuously changes ranging from one end to the other end of the first bus bar.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to an acoustic wave device and a module including the acoustic wave device. [Background technology]

[0002] Patent Document 1 discloses an acoustic wave device in which electrode fingers are provided with a wide region or the like, which can suppress spurious responses in a transverse mode. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-174595 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the acoustic wave device described in Patent Document 1, the spurious response of the transverse mode may not be sufficiently suppressed only by the wide region, etc. For this reason, it is desirable to more reliably suppress the spurious response of the transverse mode.

[0005] The present disclosure has been made to solve the above-mentioned problems. An object of the present disclosure is to provide an acoustic wave device and a module including the acoustic wave device that can more reliably suppress spurious emissions in a transverse mode. [Means for solving the problem]

[0006] An acoustic wave device according to the present disclosure includes a piezoelectric substrate, a support substrate bonded to the piezoelectric substrate, and a multi-mode resonator including a plurality of sets of IDT electrodes arranged side by side, the multi-mode resonator being formed on the piezoelectric substrate on a side opposite to the support substrate, the multi-mode resonator generating a main mode wave and a transverse mode wave when electric power is applied, wherein at least one of the plurality of sets of IDT electrodes includes a first bus bar, a second bus bar opposed to the first bus bar, a plurality of first electrode fingers connected to a side of the second bus bar in the first bus bar, the first busbar side, a plurality of first dummy electrodes connected to the second busbar side of the first busbar and facing the plurality of second electrode fingers, and a plurality of second dummy electrodes connected to the second busbar side of the first busbar and facing the plurality of first electrode fingers, wherein tips of the plurality of first electrode fingers have a first tip side wide region, tips of the plurality of second electrode fingers have a second tip side wide region, and lengths of the plurality of first dummy electrodes change continuously from one end to the other end of the first busbar.

[0007] The plurality of sets of IDT electrodes include a first bus bar, a second bus bar facing the first bus bar, a plurality of first electrode fingers connected to the second bus bar side of the first bus bar, a plurality of second electrode fingers connected to the first bus bar side of the second bus bar, a plurality of first dummy electrodes connected to the second bus bar side of the first bus bar and facing the plurality of second electrode fingers, and a plurality of first dummy electrodes connected to the first bus bar side of the second bus bar and facing the plurality of first electrode fingers. and a plurality of second dummy electrodes each including a first electrode finger and a second dummy electrode, wherein tip portions of the plurality of first electrode fingers have a first tip-side wide region, tip portions of the plurality of second electrode fingers have a second tip-side wide region, the central IDT electrode has more first electrode fingers, second electrode fingers, first dummy electrodes, and second dummy electrodes than the end-side IDT electrodes, and in the plurality of sets of IDT electrodes, lengths of the plurality of first dummy electrodes change continuously from one end to the other end of the first bus bar.

[0008] One aspect of the present disclosure is that the IDT electrode on the central side has a greater number of changes in directionality when the length of the multiple first dummy electrodes changes continuously from one end to the other end of the first bus bar than the IDT electrodes on the end sides.

[0009] According to one aspect of the present disclosure, in adjacent IDT electrodes, the lengths of the multiple first dummy electrodes change continuously across the adjacent IDT electrodes in the arrangement direction of the multiple sets of IDT electrodes.

[0010] One aspect of the present disclosure is that in the multiple sets of IDT electrodes, the lengths of the multiple first dummy electrodes have the same number of directional changes as they change continuously from one end to the other end of the first bus bar.

[0011] One aspect of the present disclosure is that in the multiple sets of IDT electrodes, the lengths of the multiple first dummy electrodes have the same directionality when continuously changing from one end to the other end of the first bus bar.

[0012] According to one aspect of the present disclosure, in adjacent IDT electrodes, the lengths of the multiple first dummy electrodes have different directionalities when continuously changing from one end to the other end of the first bus bar.

[0013] According to one aspect of the present disclosure, the lengths of the second dummy electrodes change continuously from one end to the other end of the second bus bar in inverse correlation with the lengths of the first dummy electrodes.

[0014] In one aspect of the present disclosure, the lengths of the second dummy electrodes vary continuously from one end to the other end of the second bus bar in correlation with the first dummy electrodes.

[0015] A module including the acoustic wave device is one aspect of the present disclosure. Effect of the Invention

[0016] According to the present disclosure, spurious responses in transverse modes can be more reliably suppressed. [Brief description of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of an acoustic wave device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of a resonator of the acoustic wave device according to the first embodiment. [Diagram 3] FIG. 3 is an enlarged view of a main part of FIG. 2. [Figure 4] FIG. 4 is an enlarged view of parts E and F in FIG. [Diagram 5] 5 is a diagram illustrating characteristics of the resonator of the acoustic wave device according to the first embodiment and a comparative example. FIG. [Figure 6] 11 is a diagram showing the characteristics of a resonator having the same inclined portion on a bus bar as the resonator of the acoustic wave device in the first embodiment, the same length of dummy electrodes, and a different wide region. FIG. [Figure 7] 11 is a diagram illustrating an example of a resonator of an acoustic wave device according to a second embodiment. FIG. [Figure 8] 13 is a diagram illustrating an example of a resonator of an acoustic wave device according to a third embodiment. FIG. [Figure 9] 13 is a diagram illustrating an example of a resonator of an acoustic wave device according to a fourth embodiment. FIG. [Figure 10] 13 is a diagram illustrating an example of a resonator of an acoustic wave device according to a fifth embodiment. FIG. [Figure 11] FIG. 23 is a cross-sectional view of a module to which an acoustic wave device according to a sixth embodiment is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The embodiments will be described with reference to the accompanying drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals. Duplicate descriptions of the parts will be appropriately simplified or omitted.

[0019] Embodiment 1 FIG. 1 is a cross-sectional view of an acoustic wave device according to a first embodiment.

[0020] As shown in FIG. 1, an acoustic wave device 1 includes a wiring substrate 2, a chip substrate 3, a plurality of bumps 4, and a sealing portion 5.

[0021] For example, the wiring board 2 is a multi-layer board containing resin. For example, the wiring board 2 is a low temperature co-fired ceramics (LTCC) multi-layer board made of multiple dielectric layers. For example, the wiring board 2 has a built-in passive element (not shown) such as a capacitor or an inductor.

[0022] In FIG. 1, the upper surface of the wiring board 2 is a component mounting surface. A plurality of conductive pads 2A are formed on the upper surface of the wiring board 2. For example, the plurality of conductive pads 2A are made of copper. The lower surface of the wiring board 2 is a mounting surface for a mother board or the like. A plurality of conductive pads 2B are formed on the lower surface of the wiring board 2. For example, the plurality of conductive pads 2B are made of copper. A plurality of internal conductors 2C are built into the wiring board 2. For example, the plurality of internal conductors 2C are made of copper. Each of the internal conductors 2C electrically connects the corresponding conductive pad 2A and conductive pad 2B to each other.

[0023] The chip substrate 3 faces the wiring substrate 2. For example, the chip substrate 3 includes a piezoelectric substrate 3A, a support substrate 3B, and a low acoustic velocity layer 3C. In FIG. 1, the piezoelectric substrate 3A is disposed on the lower side of the chip substrate 3. For example, the piezoelectric substrate 3A is formed of lithium tantalate, lithium niobate, or the like. The support substrate 3B is disposed on the upper side of the chip substrate 3. For example, the support substrate 3B is a polycrystalline substrate. For example, the polycrystalline substrate is C-axis oriented. For example, the support substrate 3B is formed of silicon, alumina, spinel, quartz, or the like. The support substrate 3B may be formed of glass. The low acoustic velocity layer 3C is disposed between the piezoelectric substrate 3A and the support substrate 3B. For example, the low acoustic velocity layer 3C is formed of silicon dioxide, or the like.

[0024] For example, a first filter and a second filter are formed on a main surface (lower surface in FIG. 1) of the chip substrate 3. For example, the first filter is a surface acoustic wave filter. For example, the first filter is a transmission filter. For example, the second filter is a surface acoustic wave filter. For example, the second filter is a reception filter.

[0025] The transmission filter is formed so as to pass electrical signals in a desired frequency band, and includes, for example, a ladder filter made up of a plurality of series resonators and a plurality of parallel resonators.

[0026] The receive filter is formed so as to pass electrical signals in a desired frequency band, and includes, for example, a ladder filter including a plurality of series resonators, a plurality of parallel resonators, and a multi-mode resonator.

[0027] For example, the chip substrate 3 includes a wiring pattern 3D and a plurality of electrodes 3E. For example, the plurality of electrodes 3E are interdigital transducer (IDT) electrodes having comb-shaped electrode fingers.

[0028] Each of the bumps 4 is made of gold, a conductive adhesive, solder, etc. For example, the height of the bumps 4 is 10 μm to 50 μm. Each of the bumps 4 electrically connects the conductive pad 2A and the wiring pattern 3D at a corresponding position.

[0029] The sealing portion 5 hermetically seals the chip substrate 3 together with the wiring substrate 2 while leaving a space 6 between the wiring substrate 2 and the chip substrate 3. For example, the sealing portion 5 is made of an insulating material such as a synthetic resin. The synthetic resin is an epoxy resin, a polyimide, or the like.

[0030] Next, an example of a resonator will be described with reference to FIGS. Fig. 2 is a diagram illustrating an example of a resonator of the acoustic wave device according to the first embodiment. Fig. 3 is an enlarged view of a main part of Fig. 2. Fig. 4 is an enlarged view of parts E and F of Fig. 3.

[0031] In FIG. 2, the resonator 7 is a multi-mode type SAW (Surface Acoustic Wave) resonator. The resonator 7 includes multiple sets of IDT electrodes (five sets in FIG. 2) and a pair of reflectors 8C and 8D. The multiple sets of IDT electrodes and the pair of reflectors 8C and 8D are formed on the piezoelectric substrate 3A (not shown in FIG. 2) on the side opposite to the support substrate 3B (not shown in FIG. 2). The multiple sets of IDT electrodes are arranged side by side. The reflector 8C is adjacent to one side (upper side in FIG. 2) of the multiple sets of IDT electrodes. The reflector 8D is adjacent to the other side (lower side in FIG. 2) of the multiple sets of IDT electrodes.

[0032] For example, the multiple sets of IDT electrodes and the pair of reflectors 8C, 8D are formed of an alloy of aluminum and copper. For example, the multiple sets of IDT electrodes and the pair of reflectors 8C, 8D are formed of an appropriate metal such as titanium, palladium, silver, or an alloy thereof. For example, the multiple sets of IDT electrodes and the pair of reflectors 8C, 8D are formed of a laminated metal film in which multiple metal layers are laminated. For example, the multiple sets of IDT electrodes and the pair of reflectors 8C, 8D are formed and patterned in the same process as the wiring pattern 3D (not shown in FIG. 2).

[0033] The multiple sets of IDT electrodes and the pair of reflectors 8C, 8D excite surface acoustic waves. Specifically, the multiple sets of IDT electrodes and the pair of reflectors 8C, 8D generate main mode waves and transverse mode waves when power is applied.

[0034] Each set of IDT electrodes is composed of a first IDT electrode 8A and a second IDT electrode 8B. The first IDT electrode 8A and the second IDT electrode 8B face each other. The first IDT electrode 8A includes a first bus bar 9A, a plurality of first electrode fingers 9B, and a plurality of first dummy electrodes 9C. The second IDT electrode 8B includes a second bus bar 9D, a plurality of second electrode fingers 9E, and a plurality of second dummy electrodes 9F. The central IDT electrode includes more first electrode fingers 9B, second electrode fingers 9E, first dummy electrodes 9C, and second dummy electrodes 9F than the end IDT electrodes.

[0035] The first busbar 9A has a first inclined portion X1. In the central IDT electrode, the first inclined portion X1 inclines in a direction away from the second busbar 9D from the central side toward one end and the other end of the first busbar 9A, and then inclines in a direction closer to the second busbar 9D. In the two IDT electrodes on both sides of the central IDT electrode, the first inclined portion X1 inclines in a direction closer to the second busbar 9D from the central side toward one end and the other end of the first busbar 9A. In the two outermost IDT electrodes, the first inclined portion X1 inclines in a direction farther away from the second busbar 9D as it moves away from the side of the adjacent IDT electrode.

[0036] The second busbar 9D faces the first busbar 9A. The second busbar 9D has a second inclined portion X2. In the central IDT electrode, the second inclined portion X2 inclines in a direction closer to the first busbar 9A from the central side to one end and the other end of the second busbar 9D, and then inclines in a direction farther away from the first busbar 9A. In the two IDT electrodes on both sides of the central IDT electrode, the second inclined portion X2 inclines in a direction farther away from the first busbar 9A from the central side to one end and the other end of the second busbar 9D. In the two outermost IDT electrodes, the second inclined portion X2 inclines in a direction closer to the first busbar 9A as it moves away from the side of the adjacent IDT electrode.

[0037] The multiple first electrode fingers 9B are connected to the first bus bar 9A on the side of the second bus bar 9D. The multiple first electrode fingers 9B are arranged with their longitudinal directions aligned. The multiple first electrode fingers 9B are formed so as to extend from the first bus bar 9A to the electrode finger region R. The multiple second electrode fingers 9E are connected to the second bus bar 9D on the side of the first bus bar 9A. The multiple second electrode fingers 9E are arranged with their longitudinal directions aligned. The multiple second electrode fingers 9E are formed so as to extend from the second bus bar 9D to the electrode finger region R.

[0038] The multiple first dummy electrodes 9C are connected to the first bus bar 9A on the side of the second bus bar 9D. The multiple first dummy electrodes 9C are formed in the first dummy electrode region Y1. The multiple second dummy electrodes 9F are connected to the second bus bar 9D on the side of the first bus bar 9A. The multiple second dummy electrodes 9F are formed in the second dummy electrode region Y2.

[0039] A of Fig. 3 is an enlarged view of an upper end portion of the uppermost first IDT electrode 8A in Fig. 2. Specifically, A of Fig. 3 is a detailed view of part A in Fig. 2. B of Fig. 3 is an enlarged view of a lower end portion of the uppermost first IDT electrode 8A in Fig. 2. Specifically, B of Fig. 3 is a detailed view of part A in Fig. 2. C of Fig. 3 is an enlarged view of an upper end portion of the uppermost second IDT electrode 8B in Fig. 2. Specifically, C of Fig. 3 is a detailed view of part C in Fig. 2. D of Fig. 3 is an enlarged view of a lower end portion of the uppermost second IDT electrode 8B in Fig. 2. Specifically, D of Fig. 3 is a detailed view of part D in Fig. 2.

[0040] 3, the first dummy electrodes 9C face the second electrode fingers 9E, respectively. The length of the first dummy electrodes 9C changes continuously from one end to the other end of the first inclined portion X1 of the first busbar 9A.

[0041] As shown in FIG. 2, the IDT electrode on the center side has a greater number of changes in directionality when the length of the first dummy electrodes 9C changes continuously from one end to the other end of the first busbar 9A than the IDT electrodes on the end sides. Specifically, in the center IDT electrode, the length of the first dummy electrodes 9C increases continuously from the center side to one end and the other end of the first busbar 9A, and then decreases continuously. In the two IDT electrodes on both sides of the center IDT electrode, the length of the first dummy electrodes 9C decreases continuously from the center side to one end and the other end of the first busbar 9A. In the two outermost IDT electrodes, the length of the first dummy electrodes 9C increases continuously as they move away from the side of the adjacent IDT electrode.

[0042] 3, the second dummy electrodes 9F face the first electrode fingers 9B, respectively. The lengths of the second dummy electrodes 9F change continuously from one end to the other end of the second inclined portion X2 of the second busbar 9D in inverse correlation with the lengths of the first dummy electrodes 9C.

[0043] As shown in FIG. 2, the IDT electrode on the center side has a greater number of changes in directionality when the length of the second dummy electrodes 9F changes continuously from one end to the other end of the second busbar 9D than the IDT electrodes on the end sides. Specifically, in the center IDT electrode, the length of the second dummy electrodes 9F decreases continuously from the center side to one end and the other end of the second busbar 9D, and then increases continuously. In the two IDT electrodes on both sides of the center IDT electrode, the length of the second dummy electrodes 9F increases continuously from the center side to one end and the other end of the second busbar 9D. In the two outermost IDT electrodes, the length of the second dummy electrodes 9F decreases continuously as they move away from the side of the adjacent IDT electrode.

[0044] When the wavelength of the surface acoustic wave is λ, the length of the longest first dummy electrode 9C is set to λ. The length of the shortest first dummy electrode 9C is set to approximately 0. The length of the longest second dummy electrode 9F is set to λ. The length of the shortest second dummy electrode 9F is set to approximately 0.

[0045] As shown in Fig. 4E, each of the multiple first electrode fingers 9B has a first base side wide region 10A. The first base side wide region 10A is formed at the base portion of the first electrode finger 9B. As shown in Fig. 4F, each of the multiple first electrode fingers 9B has a first tip side wide region 10B. The first tip side wide region 10B is formed at the tip portion of the first electrode finger 9B.

[0046] As shown in Fig. 4F, each of the multiple second electrode fingers 9E has a second base side wide region 10C. The second base side wide region 10C is formed at the base portion of the second electrode finger 9E. As shown in Fig. 4E, each of the multiple second electrode fingers 9E has a second tip side wide region 10D. The second tip side wide region 10D is formed at the tip portion of the second electrode finger 9E.

[0047] As shown in Fig. 4E, the first base side wide region 10A is adjacent to the second tip side wide region 10D of the adjacent second electrode finger 9E. As shown in Fig. 4F, the second base side wide region 10C is adjacent to the first tip side wide region 10B of the adjacent first electrode finger 9B.

[0048] For example, in the first base side wide region 10A, the first tip side wide region 10B, the second base side wide region 10C, and the second tip side wide region 10D, the length L in the aperture length direction is set to a length between 0.50λ and 1.75λ when the wavelength of the surface acoustic wave is λ. For example, in the first base side wide region 10A, the first tip side wide region 10B, the second base side wide region 10C, and the second tip side wide region 10D, the width W in the propagation direction of the elastic wave is set to a width of a magnification set between 1.1 times and 1.4 times the width of the corresponding electrode finger. In this embodiment, the length L in the aperture length direction is set to λ. The width W in the propagation direction of the elastic wave is set to a width of 1.2 times the width of the corresponding electrode finger.

[0049] Next, the characteristics of the resonator 7 will be described with reference to FIG. Fig. 5 is a diagram showing characteristics of the resonator of the acoustic wave device according to the first embodiment and a comparative example. The horizontal axis of Fig. 5 is frequency (MHz). The vertical axis of Fig. 5 is attenuation (dB). In Fig. 5, the passband is set to a band where the absolute value of the attenuation is 3 dB or less.

[0050] The solid line in FIG. 5 indicates the characteristics of the resonator 7 of the acoustic wave device according to the first embodiment. In the resonator 7, the total number of pairs of the IDT electrodes is 95 pairs. Specifically, the number of pairs of the central IDT electrode is set to 42.5 pairs. The number of pairs of the two IDT electrodes on both sides of the central IDT electrode is set to 22 pairs. The number of pairs of the two outermost IDT electrodes is set to 7.5 pairs. The aperture length of each IDT electrode is set to 21λ. The duty ratio (ratio of the electrode finger width to the electrode finger pitch) is set to 50%. In addition, pitch modulation and the like are added. The dashed line in FIG. 5 indicates the characteristics of a comparative example in which the inclined portion of the bus bar and the wide-width region of the electrode fingers are removed from the resonator 7 of the acoustic wave device 1 according to the first embodiment.

[0051] As shown by the dashed line in Fig. 5, in the comparative example, the absolute value of the attenuation is locally large within the passband of the comparative example. In contrast, as shown by the solid line in Fig. 5, in the resonator 7 of the acoustic wave device according to the first embodiment, the absolute value of the attenuation is suppressed from being locally large within the passband of the resonator 7. This indicates that the spurious of the transverse mode of the resonator 7 is further suppressed within the passband.

[0052] Next, differences in characteristics due to differences in the wide region will be described with reference to FIG. Fig. 6 is a diagram showing the characteristics of a resonator having the same inclined portion on the bus bar as the resonator of the acoustic wave device in embodiment 1, the same length of the dummy electrode, and a different wide region. The horizontal and vertical axes in Fig. 6 are the same as those in Fig. 5. In Fig. 6, the passband is set in the same way as in Fig. 5.

[0053] The solid line in Fig. 6 shows the characteristics of a resonator having the same inclined portion on the busbar as resonator 7 of the acoustic wave device in embodiment 1, the same length of the dummy electrode, but a different wide region. In the resonator corresponding to the solid line in Fig. 6, the length L of the wide region in the aperture length direction is 0.75λ. The width W of the wide region in the acoustic wave propagation direction is 1.20 times the width of the corresponding electrode finger. The dashed line in Fig. 6, like the dashed line in Fig. 5, shows the characteristics of a comparative example.

[0054] As shown in Fig. 6, even if the size of the wide region varies slightly, the absolute value of the attenuation is prevented from becoming locally large within the passband. This indicates that even if the size of the wide region varies slightly, the spurious response of the transverse mode of the resonator is suppressed within the passband.

[0055] According to the first embodiment described above, first electrode finger 9B has first tip-side wide region 10B. Second electrode finger 9E has second tip-side wide region 10D. The first dummy electrodes 9C change continuously from one end to the other end of first bus bar 9A. This makes it possible to more reliably suppress spurious responses in the transverse mode within the passband.

[0056] Furthermore, the IDT electrode at the center has a greater number of changes in directionality when the lengths of the first dummy electrodes 9C change continuously from one end to the other end of the first busbar 9A than the IDT electrodes at the end, making it possible to more reliably suppress spurious emissions of the transverse mode within the passband.

[0057] Moreover, the support substrate 3B is a polycrystalline substrate made of silicon, alumina, spinel, etc. Therefore, even in the resonator 7 using a polycrystalline substrate, it is possible to more reliably suppress spurious transverse modes within the passband.

[0058] Furthermore, the polycrystalline substrate serving as the support substrate 3B is C-axis oriented, so that even in the resonator 7 using the C-axis oriented polycrystalline substrate, spurious transverse modes within the passband can be more reliably suppressed.

[0059] In addition, the low acoustic velocity layer 3C is disposed between the piezoelectric substrate 3A and the support substrate 3B. Therefore, even in the resonator 7 including the low acoustic velocity layer 3C, the spurious response of the transverse mode in the passband can be more reliably suppressed.

[0060] Moreover, first electrode finger 9B has first base side wide region 10 A. Second electrode finger 9E has second base side wide region 10 C. This makes it possible to more reliably suppress spurious responses in the transverse mode within the passband.

[0061] Moreover, first base side wide region 10A is adjacent to second tip side wide region 10D of adjacent second electrode finger 9E. Second base side wide region 10C is adjacent to first tip side wide region 10B of adjacent first electrode finger 9B. This makes it possible to more reliably suppress spurious responses in the transverse mode within the passband.

[0062] Furthermore, the second dummy electrodes 9F change continuously from one end to the other end of the second busbar 9D in inverse correlation with the first dummy electrodes 9C, making it possible to more reliably suppress spurious responses in the transverse mode within the passband.

[0063] In addition, the length L in the aperture length direction of the first base wide region 10A, the first tip wide region 10B, the second base wide region 10C, and the second tip wide region 10D is set to a length between 0.50λ and 1.75λ, so that spurious responses in the transverse mode within the passband can be more reliably suppressed.

[0064] In addition, the length L in the aperture length direction may be set to a length between 0.50λ and 1.75λ in at least one of the first base wide region 10A, the first tip wide region 10B, the second base wide region 10C, and the second tip wide region 10D. In this case, the spurious of the transverse mode in the passband can be suppressed to some extent.

[0065] In addition, in the first base wide region 10A, the first tip wide region 10B, the second base wide region 10C, and the second tip wide region 10D, the width W in the propagation direction of the elastic wave is set to a width having a magnification set between 1.1 and 1.4 times the width of the corresponding electrode finger, so that spurious in the transverse mode within the passband can be more reliably suppressed.

[0066] In at least one of the first base wide region 10A, the first tip wide region 10B, the second base wide region 10C, and the second tip wide region 10D, the width W in the propagation direction of the elastic wave may be set to a width with a magnification set between 1.1 and 1.4 times the width of the corresponding electrode finger. In this case, spurious in the transverse mode within the passband can be suppressed to some extent.

[0067] In at least one of the plurality of IDT electrode sets, the length of the plurality of first dummy electrodes 9C may be continuously changed from one end to the other end of the first bus bar 9A. In this case as well, it is possible to more reliably suppress spurious responses in the transverse mode within the passband.

[0068] Furthermore, the lengths of the second dummy electrodes 9F may be varied continuously from one end to the other end of the second busbar 9D in correlation with the first dummy electrodes 9C. In this case as well, spurious responses in the transverse mode within the passband can be more reliably suppressed.

[0069] Embodiment 2 7 is a diagram illustrating an example of a resonator of an acoustic wave device according to embodiment 2. Note that the same reference numerals are used to designate the same or corresponding parts as those in embodiment 1. Description of these parts will be omitted.

[0070] As shown in FIG. 7, in the second embodiment, in adjacent IDT electrodes, the lengths of the plurality of first dummy electrodes 9C change continuously across the adjacent IDT electrodes in the arrangement direction of the plurality of IDT electrode pairs.

[0071] Specifically, in the central IDT electrode, the length of the first dummy electrodes 9C increases continuously from the central side toward one end and the other end of the first busbar 9A. In the two IDT electrodes on either side of the central IDT electrode, the length of the first dummy electrodes 9C increases continuously and then decreases continuously with increasing distance from the central IDT electrode. In the two outermost IDT electrodes, the length of the first dummy electrodes 9C decreases continuously with increasing distance from the adjacent IDT electrode.

[0072] The lengths of the multiple second dummy electrodes 9F change continuously from one end to the other end of the second inclined portion X2 of the second bus bar 9D inversely correlated with the multiple first dummy electrodes 9C.

[0073] In the second embodiment described above as well, the spurious response of the transverse mode within the passband can be more reliably suppressed.

[0074] Embodiment 3 8 is a diagram illustrating an example of a resonator of an acoustic wave device according to embodiment 3. Note that the same reference numerals are used to designate the same or corresponding parts as those in embodiment 1. Description of these parts will be omitted.

[0075] 8, in the third embodiment, in the plurality of sets of IDT electrodes, the number of changes in directionality when the lengths of the plurality of first dummy electrodes 9C continuously change from one end to the other end of the first busbar 9A is the same. Specifically, in the plurality of sets of IDT electrodes, the lengths of the plurality of first dummy electrodes 9C continuously decrease from the center toward one end and the other end of the first busbar 9A.

[0076] The lengths of the multiple second dummy electrodes 9F change continuously from one end to the other end of the second inclined portion X2 of the second bus bar 9D inversely correlated with the multiple first dummy electrodes 9C.

[0077] In the third embodiment described above as well, the spurious response of the transverse mode within the passband can be more reliably suppressed.

[0078] Embodiment 4 9 is a diagram illustrating an example of a resonator of an acoustic wave device according to embodiment 4. Note that the same reference numerals are used to designate the same or corresponding parts as those in embodiment 1. Description of these parts will be omitted.

[0079] 9, in the fourth embodiment, in the plurality of sets of IDT electrodes, the lengths of the plurality of first dummy electrodes 9C have the same directionality that continuously changes from one end to the other end of the first bus bar 9A. Specifically, the lengths of the plurality of first dummy electrodes 9C continuously decrease from one end to the other end of the first bus bar 9A.

[0080] The lengths of the multiple second dummy electrodes 9F change continuously from one end to the other end of the second inclined portion X2 of the second bus bar 9D inversely correlated with the multiple first dummy electrodes 9C.

[0081] In the fourth embodiment described above, the spurious response of the transverse mode within the passband can also be more reliably suppressed.

[0082] Embodiment 5. 10 is a diagram illustrating an example of a resonator of an acoustic wave device according to embodiment 5. Note that the same reference numerals are used to designate the same or corresponding parts as those in embodiment 1. Description of these parts will be omitted.

[0083] 10, in the fifth embodiment, the lengths of the first dummy electrodes 9C of adjacent IDT electrodes have different directionality when they change continuously from one end to the other end of the first busbar 9A. Specifically, in a first IDT electrode 8A adjacent to a first IDT electrode 8A in which the lengths of the first dummy electrodes 9C decrease continuously from one end to the other end of the first busbar 9A, the lengths of the first dummy electrodes 9C of the first IDT electrode 8A of adjacent to the first IDT electrode 8A in which the lengths of the first dummy electrodes 9C decrease continuously from one end to the other end of the first busbar 9A, the lengths of the first dummy electrodes 9C of the first IDT electrode 8A of adjacent to the first IDT electrode 8A in which the lengths of the first dummy electrodes 9C of adjacent to ...

[0084] The lengths of the multiple second dummy electrodes 9F change continuously from one end to the other end of the second inclined portion X2 of the second bus bar 9D inversely correlated with the multiple first dummy electrodes 9C.

[0085] In the fifth embodiment described above as well, the spurious response of the transverse mode within the passband can be more reliably suppressed.

[0086] Embodiment 6 11 is a cross-sectional view of a module to which the acoustic wave device according to the sixth embodiment is applied. Note that the same reference numerals are used to designate the same or corresponding parts as those in the first embodiment, and the description of these parts will be omitted.

[0087] In FIG. 11, a module 100 includes a wiring board 101 , an integrated circuit component 102 , an acoustic wave device 1 , an inductor 103 , and a sealing portion 104 .

[0088] The wiring board 101 is equivalent to the wiring board 2 of the first embodiment. The integrated circuit component 102 is mounted inside the wiring board 101. The integrated circuit component 102 includes a switching circuit and a low-noise amplifier. The acoustic wave device 1 is mounted on the main surface of the wiring board 101. The inductor 103 is mounted on the main surface of the wiring board 101. The inductor 103 is mounted for impedance matching. For example, the inductor 103 is an integrated passive device (IPD). The sealing portion 104 seals multiple electronic components including the acoustic wave device 1.

[0089] According to the sixth embodiment described above, the module 100 includes the acoustic wave device 1. Therefore, it is possible to obtain the module 100 including the acoustic wave device 1 in which spurious emissions of transverse modes within the passband are suppressed.

[0090] Having described several aspects of at least one embodiment, it should be understood that various alterations, modifications, and improvements will readily occur to those skilled in the art and are intended to be part of this disclosure, and are intended to be within the scope of this disclosure.

[0091] It should be understood that the embodiments of the method and apparatus described herein are not limited in their application to the details of construction and the arrangement of components set forth in the above description or illustrated in the accompanying drawings. The method and apparatus can be implemented in other embodiments and practiced or carried out in various ways. The specific implementation examples are provided herein for purposes of illustration only and are not intended to be limiting.

[0092] The phraseology and terminology used in this disclosure are for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "including" and variations thereof herein means the inclusion of the items listed thereafter and equivalents thereof as well as additional items.

[0093] References to "or" may be construed as meaning that any term described using "or" refers to one, more than one, and all of those described terms.

[0094] All references to front, back, left, right, top, bottom, up, down, horizontal, vertical, front and back are intended for convenience of description. Such references are not intended to limit the components of this disclosure to any one positional or spatial orientation. Accordingly, the foregoing description and drawings are by way of example only. [Explanation of symbols]

[0095] 1 Acoustic wave device, 2 Wiring board, 2A Conductive pad, 2B Conductive pad, 2C Internal conductor, 3 Chip board, 3A Piezoelectric board, 3B Support board, 3C Low acoustic velocity layer, 3D Wiring pattern, 3E Electrode, 4 Bump, 5 Sealing part, 6 Space, 7 Resonator, 8A First IDT electrode, 8B Second IDT electrode, 8C Reflector, 8D Reflector, 9A First bus bar, 9B First electrode finger, 9C First dummy electrode, 9D Second bus bar, 9E Second electrode finger, 9F Second dummy electrode, 10A First base side wide region, 10B First tip side wide region, 10C Second base side wide region, 10D Second tip side wide region, 100 Module, 101 Wiring board, 102 integrated circuit part, 103 inductor, 104 sealing part

Claims

1. A piezoelectric substrate; a support substrate bonded to the piezoelectric substrate; a multi-mode resonator including a plurality of pairs of IDT electrodes arranged side by side on the piezoelectric substrate opposite to the support substrate, the multi-mode resonator generating a main mode wave and a transverse mode wave when electric power is applied; Equipped with At least one of the plurality of sets of IDT electrodes is A first bus bar; a second bus bar facing the first bus bar; a plurality of first electrode fingers connected to the first bus bar on a side of the second bus bar; a plurality of second electrode fingers connected to the second bus bar on a side of the first bus bar; a plurality of first dummy electrodes connected to the first bus bar on a side of the second bus bar and facing the plurality of second electrode fingers; a plurality of second dummy electrodes connected to the second bus bar on a side of the first bus bar and facing the plurality of first electrode fingers; Including, The tip portions of the first electrode fingers have a first tip-side wide region, the tips of the second electrode fingers have a second tip-side wide region, An acoustic wave device in which the lengths of the plurality of first dummy electrodes change continuously from one end to the other end of the first bus bar.

2. The plurality of sets of IDT electrodes include A first bus bar; a second bus bar facing the first bus bar; a plurality of first electrode fingers connected to the first bus bar on a side of the second bus bar; a plurality of second electrode fingers connected to the second bus bar on a side of the first bus bar; a plurality of first dummy electrodes connected to the first bus bar on a side of the second bus bar and facing the plurality of second electrode fingers; a plurality of second dummy electrodes connected to the second bus bar on a side of the first bus bar and facing the plurality of first electrode fingers; Each of The tip portions of the first electrode fingers have a first tip-side wide region, the tips of the second electrode fingers have a second tip-side wide region, the IDT electrode on the central side has more first electrode fingers, more second electrode fingers, more first dummy electrodes, and more second dummy electrodes than the IDT electrodes on the end sides; The acoustic wave device according to claim 1 , wherein the lengths of the first dummy electrodes in the plurality of sets of IDT electrodes change continuously from one end to the other end of the first bus bar.

3. 3. The acoustic wave device according to claim 2, wherein the IDT electrode on the central side has a greater number of changes in directionality when the lengths of the first dummy electrodes change continuously from one end to the other end of the first bus bar than the IDT electrodes on the end sides.

4. The acoustic wave device according to claim 2 , wherein the lengths of the first dummy electrodes of adjacent IDT electrodes vary continuously across the adjacent IDT electrodes in an arrangement direction of the plurality of sets of IDT electrodes.

5. 3. The acoustic wave device according to claim 2, wherein the lengths of the first dummy electrodes in the plurality of sets of IDT electrodes are the same as the number of changes in directionality when the lengths change continuously from one end to the other end of the first bus bar.

6. The acoustic wave device according to claim 2 , wherein the lengths of the first dummy electrodes in the plurality of sets of IDT electrodes have the same directionality when continuously changing from one end to the other end of the first bus bar.

7. The acoustic wave device according to claim 2 , wherein the lengths of the first dummy electrodes of adjacent IDT electrodes are different in directionality when the lengths change continuously from one end to the other end of the first bus bar.

8. 8. The acoustic wave device according to claim 1, wherein the lengths of the second dummy electrodes change continuously from one end to the other end of the second bus bar in inverse correlation with the lengths of the first dummy electrodes.

9. 8. The acoustic wave device according to claim 1, wherein the lengths of the second dummy electrodes vary continuously from one end to the other end of the second bus bar in correlation with the lengths of the first dummy electrodes.

10. A module comprising the acoustic wave device according to claim 1 .

Images