Elastic wave device and module provided with same

Abstract

This elastic wave device is provided with: a piezoelectric substrate; a support substrate; and a multimode resonator including a plurality of sets of IDT electrodes arranged side by side, at least one of the plurality of sets of IDT electrodes including: a first bus bar, a second bus bar, a plurality of first dummy electrodes, and a plurality of second dummy electrodes; a plurality of first electrode fingers connected to the first bus bar and a plurality of second electrode fingers connected to the second bus bar; a plurality of first dummy electrodes connected to the first bus bar and facing the plurality of second electrode fingers; a plurality of second dummy electrodes connected to the second bus bar and facing the plurality of first electrode fingers; the length of the plurality of first dummy electrodes continuously changes from one end portion of the first bus bar toward the other end portion. The elastic wave device of the present invention can more reliably suppress lateral mode spurs.

Description

Technical Field

[0001] The present invention relates to an elastic wave device and a module including the elastic wave device. Background Art

[0002] Patent document 1 (Japanese Patent Publication No. 2018-174595) discloses an elastic wave device. In this elastic wave device, electrode fingers are provided with widened regions. By widening the regions, transverse mode spurious can be suppressed.

[0003] However, in the elastic wave device described in Patent Document 1, it may not be possible to sufficiently suppress transverse mode spurious emission simply by widening the region, etc. Therefore, it is desired to suppress transverse mode spurious emission more reliably. Summary of the invention

[0004] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an elastic wave device and a module including the elastic wave device, which can more reliably suppress transverse mode spurious emission.

[0005] The present invention discloses an elastic wave device, comprising: a piezoelectric substrate; a supporting substrate, the supporting substrate being bonded to the piezoelectric substrate; and a multi-mode resonator, the multi-mode resonator being formed on a side of the piezoelectric substrate away from the supporting substrate, comprising a plurality of groups of IDT electrodes arranged side by side, and generating a main mode wave and a transverse mode wave when energized; at least one of the plurality of groups of IDT electrodes comprising: a first bus bar; a second bus bar, the second bus bar facing the first bus bar; a plurality of first electrode fingers, the plurality of first electrode fingers being connected to the first bus bar on one side of the second bus bar; a plurality of second electrode fingers, the plurality of second electrode fingers being connected to the first bus bar on one side of the second bus bar to the second bus bar on one side of the first bus bar; a plurality of first dummy electrodes, the plurality of first dummy electrodes are connected to the first bus bar on one side of the second bus bar and face the plurality of second electrode fingers; and a plurality of second dummy electrodes, the plurality of second dummy electrodes are connected to the second bus bar on one side of the first bus bar and face the plurality of first electrode fingers; the front end portions of the plurality of first electrode fingers have a first front end side widened area, and the front end portions of the plurality of second electrode fingers have a second front end side widened area; the lengths of the plurality of first dummy electrodes continuously change from one end portion of the first bus bar toward the other end portion.

[0006] Further, the plurality of groups of IDT electrodes respectively include: a first bus bar; a second bus bar, the second bus bar facing the first bus bar; a plurality of first electrode fingers, the plurality of first electrode fingers connected to the first bus bar on one side of the second bus bar; a plurality of second electrode fingers, the plurality of second electrode fingers connected to the second bus bar on one side of the first bus bar; a plurality of first dummy electrodes, the plurality of first dummy electrodes connected to the first bus bar on one side of the second bus bar and facing the plurality of second electrode fingers; and a plurality of second dummy electrodes, the plurality of second dummy electrodes connected to the second bus bar on one side of the first bus bar and facing the plurality of first electrode fingers; the front ends of the plurality of first electrode fingers have a first front end widening area, the front ends of the plurality of second electrode fingers have a second front end widening area, the central IDT electrode has more first electrode fingers, second electrode fingers, first dummy electrodes and second dummy electrodes than the IDT electrodes on the end sides, and in the plurality of groups of IDT electrodes, the lengths of the plurality of first dummy electrodes continuously change from one end toward the other end of the first bus bar.

[0007] Further, in an optional embodiment of the present invention, the front ends of the plurality of first electrode fingers have a first front end side widened region, and the front ends of the plurality of second electrode fingers have a second front end side widened region.

[0008] Further, in an optional embodiment of the present invention, the roots of the plurality of first electrode fingers have a first root-side widening region, and the roots of the plurality of second electrode fingers have a second root-side widening region.

[0009] In one embodiment of the present invention, the central IDT electrode has a greater number of directional changes when the lengths of the plurality of first dummy electrodes continuously change from one end toward the other end of the first bus bar than the IDT electrodes at the end sides.

[0010] In one embodiment of the present invention, in adjacent IDT electrodes, the lengths of the plurality of first dummy electrodes vary continuously between adjacent IDT electrodes along the arrangement direction of the plurality of groups of IDT electrodes.

[0011] In one embodiment of the present invention, in the plurality of groups of IDT electrodes, when the lengths of the plurality of first dummy electrodes continuously change from one end toward the other end of the first bus bar, the number of directional changes is the same.

[0012] In one embodiment of the present invention, in the plurality of groups of IDT electrodes, when the lengths of the plurality of first dummy electrodes continuously change from one end portion toward the other end portion of the first bus bar, the directions are the same.

[0013] In one embodiment of the present invention, in adjacent IDT electrodes, when the lengths of the plurality of first dummy electrodes continuously change from one end portion toward the other end portion of the first bus bar, the directions thereof are different.

[0014] Further, the lengths of the plurality of second dummy electrodes are negatively correlated with the plurality of first dummy electrodes, and continuously change from one end portion toward the other end portion of the second bus bar.

[0015] Further, the lengths of the plurality of second dummy electrodes are related to the plurality of first dummy electrodes, and continuously change from one end portion toward the other end portion of the second bus bar.

[0016] Correspondingly, the present invention also provides a module, comprising the elastic wave device mentioned above.

[0017] According to the embodiment of the present invention, the elastic wave device of the present invention can more reliably suppress transverse mode stray. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a cross-sectional view of the elastic wave device in Embodiment 1.

[0019] Figure 2 FIG. 1 is a diagram schematically showing an example of a resonator of the elastic wave device in the first embodiment.

[0020] Figure 3 yes Figure 2 An enlarged view of the main part.

[0021] Figure 4 yes Figure 3 Enlarged views of parts E and F.

[0022] Figure 5 It is a schematic diagram showing the characteristics of the resonator of the elastic wave device in the first embodiment and that of a comparative example.

[0023] Figure 6 The characteristics of a resonator having the same inclined portion in the bus bar as that of the resonator of the elastic wave device in the first embodiment, and having dummy electrodes of the same length and different widening regions are shown.

[0024] Figure 7 FIG. 1 is a diagram schematically showing an example of a resonator of an elastic wave device according to the second embodiment.

[0025] Figure 8 FIG. 1 is a diagram schematically showing an example of a resonator of an elastic wave device according to a third embodiment.

[0026] Fig. 9 FIG. 1 is a diagram schematically showing an example of a resonator of an elastic wave device according to a fourth embodiment.

[0027] Fig.10 FIG. 1 is a diagram schematically showing an example of a resonator of an elastic wave device according to a fifth embodiment.

[0028] Fig.11 This is a cross-sectional view of a module using the elastic wave device according to the sixth embodiment.

[0029] 1 elastic wave device, 2 wiring substrate, 2A conductive pad, 2B conductive pad, 2C inner conductor, 3 chip substrate, 3A piezoelectric substrate, 3B support substrate, 3C low-speed layer, 3D wiring pattern, 3E electrode, 4 bump, 5 sealing portion, 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 root side widening area, 10B first front end side widening area, 10C second root side widening area, 10D second front end side widening area, 100 module, 101 wiring substrate, 102 integrated circuit component, 103 inductor, 104 sealing portion Specific embodiments

[0030] The embodiments are described with reference to the accompanying drawings. In addition, in each of the drawings, the same reference numerals are given to the same or equivalent parts, and the repeated description of the parts is appropriately simplified or omitted.

[0031] Implementation Method 1

[0032] Figure 1 This is a cross-sectional view of the elastic wave device in Embodiment 1.

[0033] like Figure 1 As shown, elastic wave device 1 includes wiring substrate 2 , chip substrate 3 , a plurality of bumps 4 , and sealing portion 5 .

[0034] For example, the wiring substrate 2 is a multilayer substrate containing resin. For example, the wiring substrate 2 is a low temperature co-fired ceramic (LTCC) multilayer substrate composed of a plurality of dielectric layers. For example, the wiring substrate 2 has built-in passive components (not shown) such as capacitors or inductors.

[0035] exist Figure 1In the embodiment, the upper surface of the wiring substrate 2 is a component mounting surface. A plurality of conductive pads 2A are formed on the upper surface of the wiring substrate 2. For example, the plurality of conductive pads 2A are formed of copper. The lower surface of the wiring substrate 2 is a mounting surface relative to a main substrate or the like. A plurality of conductive pads 2B are formed on the lower surface of the wiring substrate 2. For example, the plurality of conductive pads 2B are formed of copper. A plurality of internal conductors 2C are built into the wiring substrate 2. For example, the plurality of internal conductors 2C are formed of copper. The internal conductors 2C electrically connect the corresponding conductive pads 2A and conductive pads 2B, respectively.

[0036] 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-frequency layer 3C. Figure 1 In the embodiment, the piezoelectric substrate 3A is arranged on the lower side of the chip substrate 3. For example, the piezoelectric substrate 3A is formed of lithium tantalate, lithium niobate, etc. The support substrate 3B is arranged 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, crystal, etc. The support substrate 3B can also be formed of glass. The low-frequency layer 3C is arranged between the piezoelectric substrate 3A and the support substrate 3B. For example, the low-frequency layer 3C is formed of silicon dioxide, etc.

[0037] For example, on the main surface ( Figure 1 On the lower surface of the optical fiber, a first filter and a second filter are formed. For example, the first filter is a surface elastic wave filter. For example, the first filter is a transmission filter. For example, the second filter is a surface elastic wave filter. For example, the second filter is a reception filter.

[0038] The transmission filter is formed so that an electric signal of a desired frequency band can pass through it. For example, the transmission filter includes a ladder-type filter composed of a plurality of series resonators and a plurality of parallel resonators.

[0039] The reception filter is formed so that an electric signal of a desired frequency band can pass through it. For example, the reception filter includes a ladder-type filter composed of a plurality of series resonators, a plurality of parallel resonators, and a multi-mode resonator.

[0040] 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 comb-teeth-shaped electrode fingers, that is, interdigital transducer (IDT) electrodes.

[0041] The plurality of bumps 4 are made of gold, conductive adhesive, solder, etc. For example, the height of the bump 4 is 10 μm to 50 μm. The plurality of bumps 4 electrically connect the conductive pad 2A and the wiring pattern 3D at corresponding positions.

[0042] The sealing portion 5 leaves a space 6 between the wiring substrate 2 and the chip substrate 3 and seals the chip substrate 3 together with the wiring substrate 2. For example, the sealing portion 5 is formed of an insulator such as a synthetic resin, such as epoxy resin, polyimide, or the like.

[0043] Next, use Figures 2 to 4 , an example of a resonator is described.

[0044] Figure 2 FIG. 1 is a diagram schematically showing an example of a resonator of the elastic wave device in the first embodiment. Figure 3 yes Figure 2 An enlarged view of the main part. Figure 4 yes Figure 3 Enlarged views of parts E and F.

[0045] exist Figure 2 In the embodiment, the resonator 7 is a multi-mode SAW (Surface Acoustic Wave) resonator. The resonator 7 has a plurality of groups ( Figure 2 5 groups) of IDT electrodes and a pair of reflectors 8C, 8D. Multiple groups of IDT electrodes and a pair of reflectors 8C, 8D are formed on the piezoelectric substrate 3A ( Figure 2 (not shown) away from the supporting substrate 3B ( Figure 2 The reflector 8C is connected to one side of the multiple IDT electrodes (not shown). Figure 2 The reflector 8D is adjacent to the other side of the multiple IDT electrodes ( Figure 2 The middle is the lower side) adjacent.

[0046] 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 a suitable metal such as titanium, palladium, silver, or an alloy of these metals. For example, the multiple sets of IDT electrodes and the pair of reflectors 8C, 8D are formed of a laminated metal film in which a plurality of metal layers are stacked. For example, the multiple sets of IDT electrodes and the pair of reflectors 8C, 8D are formed of a laminated metal film in which a plurality of metal layers are stacked. Figure 2 The same process (not shown) is used to form the film and pattern.

[0047] The multiple sets of IDT electrodes and the pair of reflectors 8C and 8D excite surface acoustic waves. Specifically, the multiple sets of IDT electrodes and the pair of reflectors 8C and 8D generate main mode waves and transverse mode waves when power is supplied.

[0048] Each group 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. Compared with the IDT electrodes on the end side, the central IDT electrode has more first electrode fingers 9B, second electrode fingers 9E, first dummy electrodes 9C, and second dummy electrodes 9F.

[0049] The first bus bar 9A has a first inclined portion X1. In the central IDT electrode, the first inclined portion X1 is inclined from the center toward one end and the other end of the first bus bar 9A, in a direction further away from the second bus bar 9D, and then inclined in a direction further approaching the second bus bar 9D. In the two IDT electrodes on both sides of the central IDT electrode, the first inclined portion X1 is inclined from the center toward one end and the other end of the first bus bar 9A, in a direction further approaching the second bus bar 9D. In the two outermost IDT electrodes, the first inclined portion X1 is inclined in a direction further away from the second bus bar 9D as it moves away from the adjacent IDT electrode.

[0050] The second bus bar 9D faces the first bus bar 9A. The second bus bar 9D has a second inclined portion X2. In the central IDT electrode, the second inclined portion X2 is inclined from the center toward one end and the other end of the second bus bar 9D, in a direction closer to the first bus bar 9A, and then in a direction further away from the first bus bar 9A. In the two IDT electrodes on both sides of the central IDT electrode, the second inclined portion X2 is inclined from the center toward one end and the other end of the second bus bar 9D, in a direction further away from the first bus bar 9A. In the two outermost IDT electrodes, the second inclined portion X2 is inclined in a direction closer to the first bus bar 9A as it moves away from the adjacent IDT electrode.

[0051] A plurality of first electrode fingers 9B are connected to the first bus bar 9A on the side of the second bus bar 9D. The plurality of first electrode fingers 9B are arranged along the longitudinal direction of the alignment. The plurality of first electrode fingers 9B are formed to extend from the first bus bar 9A to the electrode finger region R. A plurality of second electrode fingers 9E are connected to the second bus bar 9D on the side of the first bus bar 9A. The plurality of second electrode fingers 9E are arranged along the longitudinal direction of the alignment. The plurality of second electrode fingers 9E are formed to extend from the second bus bar 9D to the electrode finger region R.

[0052] A plurality of first dummy electrodes 9C are connected to the first bus bar 9A on the side of the second bus bar 9D. A plurality of first dummy electrodes 9C are formed in the first dummy electrode region Y1. A plurality of second dummy electrodes 9F are connected to the second bus bar 9D on the side of the first bus bar 9A. A plurality of second dummy electrodes 9F are formed in the second dummy electrode region Y2.

[0053] Figure 3 A is Figure 2 The enlarged view of the upper end of the first IDT electrode 8A on the upper side. Specifically, Figure 3 A is Figure 2 Detail of section A. Figure 3 B is Figure 2 The enlarged view of the lower end of the first IDT electrode 8A on the upper side. Specifically, Figure 3 B is Figure 2 Detail of section A. Figure 3 C is Figure 2 The enlarged view of the upper end of the second IDT electrode 8B on the upper side. Specifically, Figure 3 C is Figure 2 Detail of section C in the middle. Figure 3 D is Figure 2 The enlarged view of the lower end of the second IDT electrode 8B on the uppermost side. Specifically, Figure 3 D is Figure 2 Detail of section D in the middle.

[0054] like Figure 3 As shown, the plurality of first dummy electrodes 9C and the plurality of second electrode fingers 9E face each other. The lengths of the plurality of first dummy electrodes 9C continuously change from one end toward the other end of the first inclined portion X1 of the first bus bar 9A.

[0055] like Figure 2 As shown, the central IDT electrode has a greater number of directional changes when the length of the plurality of first dummy electrodes 9C changes continuously from one end of the first bus bar 9A toward the other end than the IDT electrodes on the end side. Specifically, in the central IDT electrode, the lengths of the plurality of first dummy electrodes 9C increase continuously from the center toward one end and the other end of the first bus bar 9A, respectively, and then decrease continuously. In the two IDT electrodes on both sides of the central IDT electrode, the lengths of the plurality of first dummy electrodes 9C decrease continuously from the center toward one end and the other end of the first bus bar 9A, respectively. In the two outermost IDT electrodes, the lengths of the plurality of first dummy electrodes 9C increase continuously as they move away from the adjacent IDT electrode side.

[0056] like Figure 3As shown, the second dummy electrodes 9F face the first electrode fingers 9B. The lengths of the second dummy electrodes 9F are negatively correlated with the first dummy electrodes 9C, and continuously change from one end toward the other end of the second inclined portion X2 of the second bus bar 9D.

[0057] like Figure 2 As shown, the central IDT electrode has a greater number of directional changes when the length of the plurality of second dummy electrodes 9F changes continuously from one end of the second bus bar 9D toward the other end than the IDT electrodes on the end side. Specifically, in the central IDT electrode, the lengths of the plurality of second dummy electrodes 9F decrease continuously from the center toward one end and the other end of the second bus bar 9D, respectively, and then increase continuously. In the two IDT electrodes on both sides of the central IDT electrode, the lengths of the plurality of second dummy electrodes 9F increase continuously from the center toward one end and the other end of the second bus bar 9D, respectively. In the two outermost IDT electrodes, the lengths of the plurality of second dummy electrodes 9F decrease continuously as they move away from the adjacent IDT electrode side.

[0058] 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 almost 0. The length of the longest second dummy electrode 9F is set to λ. The length of the shortest second dummy electrode 9F is almost 0.

[0059] like Figure 4 As shown in FIG. 1E , each of the plurality of first electrode fingers 9B includes a first root-side widening region 10A. The first root-side widening region 10A is formed at the root of the first electrode finger 9B. Figure 4 As shown in FIG. 5F , each of the plurality of first electrode fingers 9B includes a first front end widened region 10B. The first front end widened region 10B is formed at the front end of the first electrode finger 9B.

[0060] like Figure 4 As shown in FIG. 1 , each of the plurality of second electrode fingers 9E includes a second root-side widening region 10C. The second root-side widening region 10C is formed at the root of the second electrode finger 9E. Figure 4 As shown in FIG. E, each of the plurality of second electrode fingers 9E includes a second front end widened region 10D. The second front end widened region 10D is formed at the front end portion of the second electrode finger 9E.

[0061] like Figure 4 As shown in FIG. 8E, the first root side widening region 10A is adjacent to the second front end side widening region 10D of the adjacent second electrode finger 9E. Figure 4 As shown in F, the second root side widening region 10C is adjacent to the first front end side widening region 10B of the adjacent first electrode finger 9B.

[0062] For example, in the first root side widening region 10A, the first front end side widening region 10B, the second root side widening region 10C, and the second front end side widening region 10D, when the wavelength of the acoustic surface wave is λ, the length L thereof is set to be between 0.50λ and 1.75λ in the direction of the opening length. For example, in the direction of travel of the elastic wave, the width W of the first root side widening region 10A, the first front end side widening region 10B, the second root side widening region 10C, and the second front end side widening region 10D is set to be between 1.1 times and 1.4 times the width of the corresponding electrode finger. In the present embodiment, in the direction of the opening length, the length L thereof is set to λ. In the direction of travel of the elastic wave, the width W thereof is set to be 1.2 times the width of the corresponding electrode finger.

[0063] Next, use Figure 5 , the characteristics of resonator 7 are described.

[0064] Figure 5 It is a schematic diagram showing the characteristics of the resonator of the elastic wave device in the first embodiment and that of a comparative example. Figure 5 The horizontal axis is frequency (MHz). Figure 5 The vertical axis is the attenuation (dB). Figure 5 The passband is set to a frequency band where the absolute value of the attenuation does not exceed 3 dB.

[0065] Figure 5 The solid line represents the characteristics of the resonator 7 of the elastic wave device in embodiment 1. In the resonator 7, the total number of pairs of multiple groups of 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 opening length of each IDT electrode is set to 21λ. The duty cycle (the ratio of the electrode finger width to the electrode finger spacing) is set to 50%. Furthermore, spacing modulation is also added. Figure 5 The dashed line represents the characteristics of a comparative example in which the inclined portion of the bus bar and the widened region of the electrode finger are deleted from resonator 7 of elastic wave device 1 in Embodiment 1.

[0066] like Figure 5 As shown by the dotted line, in the comparative example, the absolute value of the attenuation amount becomes larger locally within the passband of the comparative example. Figure 5 As shown by the solid line, in resonator 7 of the elastic wave device in Embodiment 1, the absolute value of the attenuation is suppressed from increasing locally within the passband of resonator 7. This indicates that the transverse mode spurious of resonator 7 is further suppressed within the passband.

[0067] Next, use Figure 6 , explaining the differences in characteristics caused by different widening areas.

[0068] Figure 6 The characteristics of a resonator having the same inclined portion in the bus bar as that of the resonator of the elastic wave device in the first embodiment, and having dummy electrodes of the same length and different widening regions are shown. Figure 6 The horizontal and vertical axes are Figure 5 Same. Figure 6 In the example, the passband is set to Figure 5 same.

[0069] Figure 6 The solid line of represents the characteristics of a resonator having the same inclined portion in the bus bar as resonator 7 of the elastic wave device in Embodiment 1, the same length of the dummy electrode and a different widening area. Figure 6 In the resonator corresponding to the solid line of , the length L of the widened region in the opening length direction is 0.75λ. In the propagation direction of the elastic wave, the width W of the widened region is set to 1.20 times the width of the corresponding electrode finger. Figure 6 The dotted line and Figure 5 The dashed line also represents the characteristics of the comparative example.

[0070] like Figure 6 As shown in the figure, even if the size of the widening area is slightly different, the absolute value of the attenuation amount is suppressed from becoming larger locally within the passband. This shows that even if the size of the widening area is slightly different, the transverse mode spurious of the resonator within the passband can be suppressed.

[0071] According to the above-described embodiment 1, the first electrode finger 9B has the first front end widening region 10B. The second electrode finger 9E has the second front end widening region 10D. The plurality of first dummy electrodes 9C continuously change from one end toward the other end of the first bus bar 9A. Therefore, the transverse mode spurious in the passband can be more reliably suppressed.

[0072] Furthermore, the central IDT electrode has more directivity changes when the length of the plurality of first dummy electrodes 9C changes continuously from one end to the other end of the first bus bar 9A than the end IDT electrodes, so that transverse mode spurious in the passband can be suppressed more reliably.

[0073] The support substrate 3B is a polycrystalline substrate made of silicon, alumina, spinel, etc. Therefore, in the resonator 7 using the polycrystalline substrate, the transverse mode spurious in the passband can be suppressed more reliably.

[0074] In addition, the polycrystalline substrate as the support substrate 3B is C-axis oriented. Therefore, in the resonator 7 using the C-axis oriented polycrystalline substrate, the transverse mode spurious in the passband can be suppressed more reliably.

[0075] In addition, the low-frequency layer 3C is disposed between the piezoelectric substrate 3A and the support substrate 3B. Therefore, in the resonator 7 including the low-frequency layer 3C, the transverse mode spurious in the passband can be suppressed more reliably.

[0076] In addition, the first electrode finger 9B has the first root-side widening region 10A, and the second electrode finger 9E has the second root-side widening region 10C. Therefore, the transverse mode spurious in the passband can be suppressed more reliably.

[0077] In addition, the first root side widening region 10A is adjacent to the second front end widening region 10D of the adjacent second electrode finger 9E. The second root side widening region 10C is adjacent to the first front end widening region 10B of the adjacent first electrode finger 9B. Therefore, the transverse mode spurious in the passband can be suppressed more reliably.

[0078] In addition, the plurality of second dummy electrodes 9F are negatively correlated with the plurality of first dummy electrodes 9C and continuously change from one end to the other end of the second bus bar 9D. Therefore, the transverse mode spurious in the passband can be suppressed more reliably.

[0079] In addition, the length L of the first root side widening region 10A, the first front end widening region 10B, the second root side widening region 10C, and the second front end widening region 10D in the opening length direction is set between 0.50λ and 1.75λ. Therefore, the transverse mode spurious in the passband can be suppressed more reliably.

[0080] In addition, the length L of at least one of the first root side widening region 10A, the first front end side widening region 10B, the second root side widening region 10C, and the second front end side widening region 10D in the opening length direction may be set to be between 0.50λ and 1.75λ. In this case, the transverse mode spurious in the passband can also be suppressed to some extent.

[0081] In addition, in the first root side widening region 10A, the first front end side widening region 10B, the second root side widening region 10C, and the second front end side widening region 10D, the width W is set to be between 1.1 and 1.4 times the width of the corresponding electrode finger in the propagation direction of the elastic wave. Therefore, the transverse mode spurious in the passband can be suppressed more reliably.

[0082] In addition, in at least one of the first root side widening region 10A, the first front end side widening region 10B, the second root side widening region 10C, and the second front end side widening region 10D, the width W in the propagation direction of the elastic wave may be set to be between 1.1 and 1.4 times the width of the corresponding electrode finger. In this case, the transverse mode spurious in the passband can also be suppressed to some extent.

[0083] In at least one of the plurality of IDT electrode groups, the lengths of the plurality of first dummy electrodes 9C may be continuously changed from one end toward the other end of the first bus bar 9A. In this case, transverse mode spurious in the passband can be more reliably suppressed.

[0084] Furthermore, the lengths of the second dummy electrodes 9F may be set to continuously change from one end to the other end of the second bus bar 9D in correlation with the first dummy electrodes 9C. In this case, the transverse mode spurious in the passband can be suppressed more reliably.

[0085] Implementation Method 2

[0086] Figure 7 1 is a diagram schematically showing an example of a resonator of an elastic wave device in Embodiment 2. Components identical or equivalent to those in Embodiment 1 are denoted by the same reference numerals, and description of such components will be omitted.

[0087] like Figure 7 As shown, in the second embodiment, in adjacent IDT electrodes, the lengths of the plurality of first dummy electrodes 9C continuously change between adjacent IDT electrodes along the arrangement direction of the plurality of groups of IDT electrodes.

[0088] Specifically, in the central IDT electrode, the lengths of the plurality of first dummy electrodes 9C continuously increase from the center toward one end and the other end of the first bus bar 9A. In the two IDT electrodes on both sides of the central IDT electrode, the lengths of the plurality of first dummy electrodes 9C continuously increase as they move away from the central IDT electrode, and then continuously decrease. In the two outermost IDT electrodes, the lengths of the plurality of first dummy electrodes 9C continuously decrease as they move away from the adjacent IDT electrode.

[0089] The lengths of the plurality of second dummy electrodes 9F are negatively correlated with the lengths of the plurality of first dummy electrodes 9C, and continuously change from one end portion toward the other end portion of the second inclined portion X2 of the second bus bar 9D.

[0090] In the second embodiment described above, the transverse mode spurious in the passband can be suppressed more reliably.

[0091] Implementation 3

[0092] Figure 8 1 is a diagram schematically showing an example of a resonator of an elastic wave device in Embodiment 3. Components identical or equivalent to those in Embodiment 1 are denoted by the same reference numerals, and description of such components will be omitted.

[0093] like Figure 8As shown, in Embodiment 3, in the plurality of IDT electrodes, the number of directional changes when the length of the plurality of first dummy electrodes 9C changes continuously from one end toward the other end of the first bus bar 9A is the same. Specifically, in the plurality of IDT electrodes, the length of the plurality of first dummy electrodes 9C decreases continuously from the center toward one end and the other end of the first bus bar 9A.

[0094] The lengths of the plurality of second dummy electrodes 9F are negatively correlated with the lengths of the plurality of first dummy electrodes 9C, and continuously change from one end portion toward the other end portion of the second inclined portion X2 of the second bus bar 9D.

[0095] In the third embodiment described above, the transverse mode spurious emission in the passband can be suppressed more reliably.

[0096] Implementation 4

[0097] Fig. 9 1 is a diagram schematically showing an example of a resonator of an elastic wave device in Embodiment 4. Components identical or equivalent to those in Embodiment 1 are denoted by the same reference numerals, and description of such components will be omitted.

[0098] like Fig. 9 As shown, in Embodiment 4, in the plurality of IDT electrode groups, the lengths of the plurality of first dummy electrodes 9C continuously change in the same direction from one end of the first bus bar 9A toward the other end. Specifically, the lengths of the plurality of first dummy electrodes 9C continuously decrease from one end of the first bus bar 9A toward the other end.

[0099] The lengths of the plurality of second dummy electrodes 9F are negatively correlated with the lengths of the plurality of first dummy electrodes 9C, and continuously change from one end portion toward the other end portion of the second inclined portion X2 of the second bus bar 9D.

[0100] In the fourth embodiment described above, the transverse mode spurious emission in the passband can be suppressed more reliably.

[0101] Implementation method 5

[0102] Fig.10 1 is a diagram schematically showing an example of a resonator of an elastic wave device in Embodiment 5. Components identical or equivalent to those in Embodiment 1 are denoted by the same reference numerals, and description of such components will be omitted.

[0103] like Fig.10As shown, in Embodiment 5, in adjacent IDT electrodes, the directionality of the lengths of the plurality of first dummy electrodes 9C when continuously changing from one end toward the other end of the first bus bar 9A is different. Specifically, in a first IDT electrode 8A in which the lengths of the plurality of first dummy electrodes 9C continuously decrease from one end toward the other end of the first bus bar 9A, the lengths of the plurality of first dummy electrodes 9C continuously increase from one end toward the other end of the first IDT electrode 8A adjacent thereto.

[0104] The lengths of the plurality of second dummy electrodes 9F are negatively correlated with the lengths of the plurality of first dummy electrodes 9C, and continuously change from one end portion toward the other end portion of the second inclined portion X2 of the second bus bar 9D.

[0105] In the fifth embodiment described above, the transverse mode spurious in the passband can be suppressed more reliably.

[0106] Implementation 6

[0107] Fig.11 1 is a cross-sectional view of a module using the elastic wave device in Embodiment 6. The same reference numerals are used to designate the same or equivalent components as those in Embodiment 1, and description of such components will be omitted.

[0108] exist Fig.11 In the embodiment, module 100 includes wiring board 101 , integrated circuit component 102 , elastic wave device 1 , inductor 103 , and sealing portion 104 .

[0109] The wiring substrate 101 is equivalent to the wiring substrate 2 of the first embodiment. The integrated circuit component 102 is mounted inside the wiring substrate 101. The integrated circuit component 102 includes a switch circuit and a low noise amplifier. The elastic wave device 1 is mounted on the main surface of the wiring substrate 101. The inductor 103 is mounted on the main surface of the wiring substrate 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 a plurality of electronic components including the elastic wave device 1.

[0110] According to the sixth embodiment described above, module 100 includes elastic wave device 1. Therefore, module 100 including elastic wave device 1 capable of suppressing transverse mode spurious emission within a passband can be obtained.

[0111] Although several aspects of at least one embodiment have been described, it should be understood that various changes, modifications and improvements will readily occur to those skilled in the art, which are part of the present disclosure and fall within the scope of the present disclosure.

[0112] It should be understood that the embodiments of the methods and devices described herein are not limited in application to the structural and arrangement details of the constituent elements described above or illustrated in the accompanying drawings. The methods and devices may be implemented in other embodiments and implemented or executed in various ways. The specific implementation examples given herein are for illustrative purposes only and are not limited thereto.

[0113] The expressions and terms used in this disclosure are for illustrative purposes only and should not be considered as limiting. The words "include", "have", "have", "include" and their variations herein mean including the items described below and their equivalents and additional items.

[0114] Referring to "or", any term described using "or" may be interpreted to mean one, more than one, and all of the terms.

[0115] The terms front, back, left, right, top, bottom, up, down, horizontal, vertical, inside, outside, etc. are for the convenience of description. Such terms do not mean that the components of the present disclosure are limited to any one position or spatial arrangement. Therefore, the above description and drawings are only examples.

Claims

1. An elastic wave device, characterized in that: have: Piezoelectric substrate; a supporting substrate bonded to the piezoelectric substrate; as well as A multi-mode resonator, which is formed on a side of the piezoelectric substrate away from the supporting substrate, includes a plurality of groups of IDT electrodes arranged side by side, and generates a main mode wave and a transverse mode wave when powered on; At least one of the plurality of groups of IDT electrodes comprises: First bus bar; a second bus bar, the second bus bar facing the first bus bar; a plurality of first electrode fingers connected to the first bus bar on one side of the second bus bar; a plurality of second electrode fingers, the plurality of second electrode fingers being connected to the second bus bar on one side of the first bus bar; a plurality of first dummy electrodes, the plurality of first dummy electrodes being connected to the first bus bar at one side of the second bus bar and facing the plurality of second electrode fingers; and a plurality of second dummy electrodes, the plurality of second dummy electrodes being connected to the second bus bar at one side of the first bus bar and facing the plurality of first electrode fingers; The front ends of the plurality of first electrode fingers have a first front end widened region, and the front ends of the plurality of second electrode fingers have a second front end widened region; The lengths of the plurality of first dummy electrodes continuously change from one end portion toward the other end portion of the first bus bar.

2. The elastic wave device according to claim 1, characterized in that: The multiple groups of IDT electrodes respectively include: First bus bar; a second bus bar, the second bus bar facing the first bus bar; a plurality of first electrode fingers connected to the first bus bar on one side of the second bus bar; a plurality of second electrode fingers, the plurality of second electrode fingers being connected to the second bus bar on one side of the first bus bar; a plurality of first dummy electrodes, the plurality of first dummy electrodes being connected to the first bus bar at one side of the second bus bar and facing the plurality of second electrode fingers; as well as a plurality of second dummy electrodes, the plurality of second dummy electrodes being connected to the second bus bar at one side of the first bus bar and facing the plurality of first electrode fingers; Compared with the IDT electrodes at the end sides, the central IDT electrode has more first electrode fingers, second electrode fingers, first dummy electrodes, and second dummy electrodes; In the plurality of IDT electrode groups, lengths of the plurality of first dummy electrodes continuously change from one end portion toward the other end portion of the first bus bar.

3. The elastic wave device according to claim 2, characterized in that: The center IDT electrode has a greater number of directional changes when the lengths of the plurality of first dummy electrodes continuously change from one end toward the other end of the first bus bar than the end IDT electrodes.

4. The elastic wave device according to claim 2, characterized in that: In adjacent IDT electrodes, lengths of the plurality of first dummy electrodes vary continuously between adjacent IDT electrodes along an arrangement direction of the plurality of groups of IDT electrodes.

5. The elastic wave device according to claim 2, characterized in that: In the plurality of IDT electrode groups, when the lengths of the plurality of first dummy electrodes continuously change from one end portion toward the other end portion of the first bus bar, the number of directional changes is the same.

6. The elastic wave device according to claim 2, characterized in that: In the plurality of IDT electrode groups, when the lengths of the plurality of first dummy electrodes continuously change from one end portion toward the other end portion of the first bus bar, the directions thereof are the same.

7. The elastic wave device according to claim 2, characterized in that: In adjacent IDT electrodes, when the lengths of the plurality of first dummy electrodes continuously change from one end portion toward the other end portion of the first bus bar, the directionality is different.

8. The elastic wave device according to any one of claims 1 to 7, characterized in that: The lengths of the second dummy electrodes are negatively correlated with the lengths of the first dummy electrodes, and continuously change from one end portion toward the other end portion of the second bus bar.

9. The elastic wave device according to any one of claims 1 to 7, characterized in that: The lengths of the second dummy electrodes are related to the first dummy electrodes and continuously change from one end portion toward the other end portion of the second bus bar.

10. A module, characterized in that: An elastic wave device according to any one of claims 1 to 9.

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