Elastic wave device and module provided with same

Abstract

The invention discloses an elastic wave device and a module thereof. A resonator of the elastic wave device comprises a first bus bar, a second bus bar and a plurality of first electrode fingers, wherein the first bus bar and the second bus bar are oppositely arranged; the plurality of first electrode fingers are connected with the first bus bar; a plurality of second electrode fingers, which are connected to the second bus bar; a plurality of first dummy electrodes which are connected to the first bus bar, and which face the plurality of second electrode fingers; a plurality of second dummy electrodes which are connected to the second bus bar and face the plurality of first electrode fingers; the tip of the plurality of first electrode fingers has a first tip-side wide region, the tip of the plurality of second electrode fingers has a second tip-side wide region, and the plurality of first dummy electrodes gradually become shorter from one end to the other end of the first bus bar. According to the elastic wave device, stray of a transverse mode can be suppressed more reliably.

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 the elastic wave device, a portion such as a wide area of ​​an electrode finger is provided. The wide area and the like can suppress the spurious of the transverse mode.

[0003] However, in the elastic wave device described in Patent Document 1, the spurious emission of the transverse mode may not be sufficiently suppressed only in a portion such as a wide region. Therefore, it is desired to suppress the spurious emission of the transverse mode more reliably. Summary of the invention

[0004] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide an elastic wave device capable of more reliably suppressing the spurious occurrence of a transverse mode, and a module including the elastic wave device.

[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; a resonator, the resonator being formed on the piezoelectric substrate on the opposite side of the supporting substrate, and generating a main mode wave and a transverse mode wave when power is applied; the resonator comprising: a first bus bar; a second bus bar, the second bus bar facing the first bus bar; a plurality of first electrode fingers, on the side of the second bus bar, a plurality of the first electrode fingers being connected to the first bus bar; a plurality of second electrode fingers, on the side of the first bus bar, a plurality of the second electrode fingers being connected to the A second bus bar is connected; a plurality of first virtual electrodes, on the side of the second bus bar, the plurality of first virtual electrodes are connected to the first bus bar and face the plurality of second electrode fingers; a plurality of second virtual electrodes, on the side of the first bus bar, the plurality of second virtual electrodes are connected to the second 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 wide area, the front end portions of the plurality of second electrode fingers have a second front end side wide area, and the plurality of first virtual electrodes gradually become shorter from one end to the other end of the first bus bar.

[0006] Further, optionally, the support substrate is a polycrystalline substrate formed of silicon, alumina, spinel or glass.

[0007] In a specific embodiment of the present invention, the polycrystalline substrate is C-axis oriented.

[0008] Furthermore, the elastic wave device of the present invention further includes: a low acoustic velocity layer, wherein the low acoustic velocity layer is disposed between the piezoelectric substrate and the supporting substrate.

[0009] Further, the roots of the plurality of first electrode fingers have a first root-side wide region, and the roots of the plurality of second electrode fingers have a second root-side wide region.

[0010] Furthermore, in the plurality of first electrode fingers, the first root side wide region is adjacent to the second front end side wide region of the adjacent second electrode finger, and in the plurality of second electrode fingers, the second root side wide region is adjacent to the first front end side wide region of the adjacent first electrode finger.

[0011] Furthermore, the lengths of the plurality of second virtual electrodes are inversely correlated with the lengths of the plurality of first virtual electrodes, and gradually become longer from one end to the other end of the second bus bar.

[0012] Further, in the opening length direction, the length of the wide area of ​​the plurality of first electrode fingers or the length of the wide area of ​​the plurality of second electrode fingers is set between 0.50λ and 1.75λ.

[0013] Furthermore, in the traveling direction of the elastic wave, the width of the wide region of the plurality of first electrode fingers or the width of the wide region of the plurality of second electrode fingers is set between 1.1 and 1.4 times the electrode finger width. The width of the wide region of the front end side of the plurality of first electrode fingers is between 1.1 and 1.4 times the electrode finger width; the width of the wide region of the front end side of the plurality of second electrode fingers is set between 1.1 and 1.4 times the electrode finger width.

[0014] Further, the length of the virtual electrode connected to the other end of the first bus bar is between 0.125 times and 0.500 times the length of the virtual electrode connected to one end of the first bus bar; or, the length of the virtual electrode connected to one end of the second bus bar is between 0.125 times and 0.500 times the length of the virtual electrode connected to the other end of the second bus bar.

[0015] Correspondingly, the present invention also discloses a module, comprising the elastic wave device mentioned above.

[0016] According to the elastic wave device of the present disclosure, it is possible to more reliably suppress spurious generation of a transverse mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a cross-sectional view of the elastic wave device in Embodiment 1.

[0018] Figure 2 FIG. 1 is a diagram showing an example of a resonator of the elastic wave device according to the first embodiment.

[0019] Figure 3 yes Figure 2Enlarged views of parts A, B, C and D in FIG.

[0020] Figure 4 yes Figure 3 Enlarged views of parts E and F in FIG.

[0021] Figure 5 This is a diagram showing characteristics of a resonator according to a comparative example of the elastic wave device in the first embodiment.

[0022] Figure 6 This is a diagram showing characteristics of a comparative example resonator in Embodiment 1, which has the same inclined portion as the resonator of the elastic wave device in the bus bar, has the same dummy electrode length, and does not have a wide region.

[0023] Figure 7 The diagram shows the characteristics of a comparative example resonator having a different inclined portion in the bus bar from the resonator of the elastic wave device in the first embodiment, a different dummy electrode length, and a different wide region.

[0024] Figure 8 This is a diagram showing characteristics of a comparative example resonator having the same inclined portion as that of the resonator of the elastic wave device in the bus bar and the same dummy electrode length and having a different width region in the first embodiment.

[0025] Fig. 9 This is a diagram showing characteristics of a comparative example resonator having the same inclined portion as that of the resonator of the elastic wave device in the bus bar and the same dummy electrode length and having a different width region in the first embodiment.

[0026] Fig.10 FIG. 1 is a diagram showing an example of a resonator of an elastic wave device according to the second embodiment.

[0027] Fig.11 yes Fig.10 Enlarged views of parts A, B, C and D of the invention.

[0028] Fig.12 The graph shows the characteristics of the elastic wave device resonator in Embodiment 2, the resonator having the same dummy electrode length but without the wide region, and the characteristics of the resonator as a comparative example.

[0029] Fig.13 Graphs 1 and 2 show characteristics of an elastic wave device resonator in Embodiment 2, a resonator having different dummy electrode lengths but not having a wide region, and a comparative example thereof.

[0030] Fig.14 This is a cross-sectional view of an elastic wave device in Embodiment 3 applied to a module.

[0031] 1 elastic wave device, 2 wiring substrate, 2A conductive pad, 2B conductive pad, 2C internal conductor, 3 chip substrate, 3A piezoelectric substrate, 3B supporting substrate, 3C low acoustic velocity layer, 3D wiring pattern, 3E electrode, 4 bump, 5 sealing portion, 6 space, 8 resonator, 8A first IDT electrode, 8B second IDT electrode, 8C first reflector, 8D second 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 wide region, 10B first front end side wide region, 10C second root side wide region, 10D second front end side wide region, 100 module, 101 wiring substrate, 102 integrated circuit component, 103 inductor, 104 sealing portion. DETAILED DESCRIPTION

[0032] The embodiments are described with reference to the accompanying drawings. In addition, in each figure, the same or corresponding parts are marked with the same reference numerals, and the repeated description of the parts is appropriately simplified or omitted.

[0033] Implementation Method 1

[0034] Figure 1 FIG. 4 is a cross-sectional view of the elastic wave device in Embodiment 1. Figure 1 As shown, elastic wave device 1 includes a wiring substrate 2 , a chip substrate 3 , a plurality of bumps 4 , and a sealing portion 5 .

[0035] 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 elements such as capacitors and inductors (not shown).

[0036] exist Figure 1 In the embodiment, the upper surface of the wiring substrate 2 is a component mounting surface. A plurality of conductive pads (solder 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 mounted on a mother 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.

[0037] 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. Figure 1In 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 materials such as silicon, alumina, spinel, crystal, and glass. The low acoustic velocity layer 3C is arranged between the piezoelectric substrate 3A and the support substrate 3B. For example, the low acoustic velocity layer 3C is formed of materials such as silicon dioxide.

[0038] For example, on the main surface ( Figure 1 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.

[0039] The transmission filter is formed so as to be able to pass an electrical signal in a desired frequency band. For example, the transmission filter includes a ladder-type filter composed of a plurality of series resonators and a plurality of parallel resonators.

[0040] The reception filter is formed so as to be able to pass an electrical signal in a desired frequency band. For example, the reception filter includes a ladder-type filter composed of a plurality of series resonators and a plurality of parallel resonators.

[0041] 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.

[0042] The plurality of bumps 4 are respectively 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 to the wiring pattern 3D at corresponding positions. The sealing portion 5 reserves a space 6 between the wiring substrate 2 and the chip substrate 3, and hermetically 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. The synthetic resin is an epoxy resin, a polyimide, etc.

[0043] Next, use Figures 2 to 4 An example of a resonator will be described.

[0044] Figure 2 FIG. 1 is a diagram showing an example of an elastic wave device resonator in the first embodiment. Figure 3 yes Figure 2 Enlarged views of parts A, B, C and D of the invention. Figure 4 yes Figure 3 Enlarged views of parts E and F.

[0045] exist Figure 2In the embodiment, the resonator 8 is a SAW (Surface Acoustic Wave) resonator. The resonator 8 includes a first IDT electrode 8A, a second IDT electrode 8B, a first reflector 8C, and a second reflector 8D. The first IDT electrode 8A, the second IDT electrode 8B, the first reflector 8C, and the second reflector 8D are formed on the piezoelectric substrate 3A (on the Figure 2 (not shown in the figure) is formed on the support substrate 3B (in Figure 2 The first IDT electrode 8A and the second IDT electrode 8B face each other. The first reflector 8C is located on one side of the first IDT electrode 8A and the second IDT electrode 8B (not shown). Figure 2 The second reflector 8D is adjacent to the first IDT electrode 8A and the other side of the second IDT electrode 8B (in Figure 2 The middle is the lower side) adjacent.

[0046] For example, the first IDT electrode 8A, the second IDT electrode 8B, the first reflector 8C, and the second reflector 8D are formed of an alloy of aluminum and copper. For example, the first IDT electrode 8A, the second IDT electrode 8B, the first reflector 8C, and the second reflector 8D are formed of a suitable metal such as titanium, palladium, silver, or an alloy of these metals. For example, the first IDT electrode 8A, the second IDT electrode 8B, the first reflector 8C, and the second reflector 8D are formed of a laminated metal film having a plurality of metal layers laminated thereon. For example, the first IDT electrode 8A, the second IDT electrode 8B, the first reflector 8C, and the second reflector 8D are formed in a manner similar to that of the wiring pattern 3D (in Figure 2 The film formation and patterning are performed by the same process (not shown).

[0047] The first IDT electrode 8A, the second IDT electrode 8B, the first reflector 8C, and the second reflector 8D can excite surface acoustic waves. Specifically, the first IDT electrode 8A, the second IDT electrode 8B, the first reflector 8C, and the second reflector 8D generate main mode waves and transverse mode waves when power is applied.

[0048] The first IDT electrode 8A includes a first bus bar 9A, a plurality of first electrode fingers 9B ( Figure 2 ) and a plurality of first virtual electrodes 9C (in Figure 2 The second IDT electrode 8B includes a second bus bar 9D and a plurality of second electrode fingers 9E (in Figure 2 (not shown) and a plurality of second virtual electrodes 9F (in Figure 2 (not shown in the figure).

[0049] The first bus bar 9A and the second bus bar 9D face each other. The first bus bar 9A has a first inclined portion X1. The first inclined portion X1 is formed so that the other side of the first bus bar 9A is closer to the second bus bar 9D. The second bus bar 9D has a second inclined portion X2. The second inclined portion X2 is formed so that one side of the second bus bar 9D is closer to the first bus bar 9A.

[0050] On the side of the second bus bar 9D, a plurality of first electrode fingers 9B are connected to the first bus bar 9A. The plurality of first electrode fingers 9B are arranged in the length direction thereof. The plurality of first electrode fingers 9B are formed to extend from the first bus bar 9A to the electrode finger region R. On the side of the first bus bar 9A, a plurality of second electrode fingers 9E are connected to the second bus bar 9D. The plurality of second electrode fingers 9E are arranged in the length direction thereof. The plurality of second electrode fingers 9E are formed to extend from the second bus bar 9D to the electrode finger region R.

[0051] On the second bus bar 9D side, a plurality of first dummy electrodes 9C are connected to the first bus bar 9A. The plurality of first dummy electrodes 9C are formed in the first dummy electrode region Y1. On the first bus bar 9A side, a plurality of second dummy electrodes 9F are connected to the second bus bar 9D. The plurality of second dummy electrodes 9F are formed in the second dummy electrode region Y2.

[0052] like Figure 3 As shown, the plurality of first virtual electrodes 9C are respectively opposite to the plurality of second electrode fingers 9E, and the spacing between the plurality of first virtual electrodes 9C and the plurality of second electrode fingers 9E is 0.1λ to 0.2λ. The length of the plurality of first virtual electrodes 9C gradually shortens from one end to the other end of the first inclined portion X1 of the first bus bar 9A. The plurality of second virtual electrodes 9F are respectively opposite to the plurality of first electrode fingers 9B, and the spacing between the plurality of second virtual electrodes 9F and the plurality of first electrode fingers 9B is 0.1λ to 0.2λ. The length of the plurality of second virtual electrodes 9F is inversely correlated with the length of the plurality of first virtual electrodes 9C, and gradually lengthens from one end to the other end of the second inclined portion X2 of the second bus bar 9D.

[0053] When the wavelength of the surface acoustic wave is λ, the length of the uppermost first dummy electrode 9C is set to λ. The length of the lowermost first dummy electrode 9C is set to approximately 0. The length of the uppermost second dummy electrode 9F is set to approximately 0. The length of the lowermost second dummy electrode 9F is set to λ.

[0054] like Figure 4 As shown in E in FIG. 8 , each of the plurality of first electrode fingers 9B includes a first root-side wide region 10A. Figure 4 As shown at G in FIG. 1 , the first root side wide region 10A is formed at the root of the first electrode finger 9B. Figure 4As shown in F in FIG. 1 , each of the plurality of first electrode fingers 9B includes a first front end wide region 10B. The first front end wide region 10B is formed at the front end of the first electrode finger 9B.

[0055] like Figure 4 As shown in F in FIG. 8 , each of the plurality of second electrode fingers 9E includes a second root-side wide region 10C. Figure 4 As shown at H in FIG. 1 , the second root side wide region 10C is formed at the root of the second electrode finger 9E. Figure 4 As shown in E in FIG. 1 , each of the plurality of second electrode fingers 9E includes a second front end wide region 10D. The second front end wide region 10D is formed at the front end portion of the second electrode finger 9E.

[0056] like Figure 4 As shown in E in FIG. 1 , the first root side wide region 10A is adjacent to the second front end side wide region 10D of the adjacent second electrode finger 9E. Figure 4 As shown in F in FIG. 8 , the second root-side wide region 10C is adjacent to the first tip-side wide region 10B of the adjacent first electrode finger 9B.

[0057] For example, in the first root side wide width region 10A, the first front side wide width region 10B, the second root side wide width region 10C, and the second front side wide width region 10D, when the wavelength of the acoustic surface wave is λ, the length L of the wide width region in the opening length direction is set in the range of 0.50λ to 1.75λ. For example, in the traveling direction of the elastic wave, the width W of the first root side wide width region 10A, the first front side wide width region 10B, the second root side wide width region 10C, and the second front side wide width region 10D is set to 1.1 to 1.4 times the electrode finger width, where the electrode finger width is W1, and the value range of W / W1 is 1.1 to 1.4. In the present embodiment, in the opening length direction, the length L of the wide width region is set to λ. In the traveling direction of the elastic wave, the width W of the wide width region is set to 1.2 times the corresponding electrode finger width.

[0058] Next, use Figure 5 The characteristics of the resonator 8 will be described. Figure 5 This is a diagram showing characteristics of a resonator according to a comparative example of the elastic wave device in the first embodiment. Figure 5 The horizontal axis is frequency (MHz). Figure 5 The vertical axis is conductance (dB).

[0059] exist Figure 5In the figure, the solid line Z1 represents the characteristics of the resonator 8 of the elastic wave device 1 in the first embodiment. In the resonator 8, the capacitance is set to 3.385 pF. The number of pairs of IDT electrodes is set to 81.5 pairs, and the opening length is set to 20.4λ. The duty cycle (the ratio of the width of the electrode finger to the spacing between the electrode fingers) is set to 50%. The dotted line Z2 is a comparison column, which represents the characteristics of a comparative example after deleting the inclined portion of the bus bar and the wide area of ​​the electrode fingers from the resonator 8 of the elastic wave device 1 in the first embodiment. In this comparative example, the capacitance, the number of pairs of electrode fingers, the opening length and the duty cycle are the same as those of the resonator 8.

[0060] like Figure 5 As shown, in the dotted line Z2, the conductance value is locally increased in the region M between the resonance frequency fr and the anti-resonance frequency fa. In contrast, in the solid line Z1, the conductance value is suppressed from being locally increased in the region M between the resonance frequency fr and the anti-resonance frequency fa. This indicates that the spurious of the transverse mode of the resonator 8 of the first embodiment is further suppressed between the resonance frequency fr and the anti-resonance frequency fa.

[0061] Next, use Figure 6 and Figure 7 , the difference in characteristics caused by the difference in the length of the virtual electrode is explained.

[0062] Figure 6 This is a diagram showing characteristics of a comparative example resonator in Embodiment 1, which has the same inclined portion as the resonator of the elastic wave device in the bus bar, has the same dummy electrode length, and does not have a wide region. Figure 7 The diagram shows the characteristics of a comparative example resonator having a different inclined portion in the bus bar from the resonator of the elastic wave device in the first embodiment, a different dummy electrode length, and a different wide region. Figure 6 and Figure 7 The horizontal and vertical axes in Figure 5 same.

[0063] exist Figure 6 In the figure, the solid line Z1 is the characteristic of a resonator in Embodiment 1, which has the same inclined portion in the bus bar as the resonator 8 of the elastic wave device 1, has the same length of the virtual electrode, and does not have a wide area. In this resonator, the capacitance is set to 3.537pF. The number of pairs of electrode fingers is set to 103 pairs, and the opening length is set to 17.5λ. The duty cycle is set to 55%. The dotted line Z2 is the characteristic of a comparative example in which the inclined portion of the bus bar and the wide area of ​​the electrode fingers are deleted from the resonator 8 of the elastic wave device 1 in Embodiment 1. In this comparative example, the capacitance is set to 3.537pF. The number of pairs of electrode fingers is set to 100 pairs. The opening length is set to 18.1λ. The duty cycle is set to 55%.

[0064] exist Figure 7 In the figure, the solid line Z1 is the characteristic of the resonator in Embodiment 1, which has a different inclined portion in the bus bar from the resonator 8, a different length of the virtual electrode, and a different width region. In the resonator 8, the capacitance value, the number of pairs of electrode fingers, the opening length, and the duty ratio are the same as those corresponding to Figure 6 The dotted line Z2 is the same as the resonator 8. Figure 6 The same as the dotted line Z2.

[0065] exist Figure 7 In (a), the length of the uppermost first dummy electrode 9C is set to 0.5λ. The length of the lowermost second dummy electrode 9F is set to 0.5λ. Figure 7 In (b), the length of the uppermost first dummy electrode 9C is set to 1.5λ. The length of the lowermost second dummy electrode 9F is set to 1.5λ. Figure 7 In (c), the length of the uppermost first dummy electrode 9C is set to 2.0λ. The length of the lowermost second dummy electrode 9F is set to 2.0λ.

[0066] like Figure 6 As shown, in the solid line Z1, the conductance value is suppressed from increasing locally in the frequency band slightly lower than the antiresonance frequency fa. This means that the spurious of the transverse mode of the resonator corresponding to the solid line Z1 is suppressed in the frequency band slightly lower than the antiresonance frequency fa.

[0067] like Figure 7 As shown, in the solid line Z1, the conductance value is suppressed from increasing locally in the frequency band slightly lower than the antiresonance frequency fa. This means that even in the resonator corresponding to the solid line Z1, the spurious of the transverse mode can be suppressed to a certain extent in the frequency band slightly lower than the antiresonance frequency fa.

[0068] Next, use Figure 8 and Fig. 9 , explaining the difference in characteristics caused by the difference in width area. Figure 8 and Fig. 9 This is a diagram showing characteristics of a comparative example resonator having the same inclined portion as that of the resonator of the elastic wave device in the bus bar and the same dummy electrode length and having a different width region in the first embodiment. Figure 8 and Fig. 9 The horizontal and vertical axes are Figure 5 same.

[0069] exist Figure 8 and Fig. 9In the figure, the solid line Z1 is the characteristic of a resonator having the same inclined portion in the bus bar as the resonator 8 of the elastic wave device 1, the same length of the virtual electrode, and a different width region in the embodiment 1. In this resonator, the capacitance value, the number of pairs of electrode fingers, the opening length, and the duty ratio are the same as those corresponding to Figure 5 The dotted line Z2 corresponds to Figure 5 The same is true for the comparative example.

[0070] exist Figure 8 In (a), the length L of the wide area in the opening length direction is 0.50λ. In the propagation direction of the elastic wave, the width W of the wide area is 1.25 times the electrode finger width. Figure 8 In (b), the length L of the wide area in the opening length direction is 0.75λ. In the propagation direction of the elastic wave, the width W of the wide area is 1.20 times the electrode finger width. Fig. 9 In (a), the length L of the wide area in the opening length direction is λ. In the propagation direction of the elastic wave, the width W of the wide area is 1.15 times the electrode finger width. Fig. 9 In (b), the length L of the wide region in the opening length direction is λ. The width W of the wide region in the propagation direction of the elastic wave is 1.25 times the electrode finger width.

[0071] like Figure 8 and Fig. 9 As shown, in the solid line Z1, the conductance value is suppressed from increasing locally in a frequency band slightly higher than the resonance frequency fr. This means that even the resonator corresponding to the solid line Z1 can suppress the spurious transverse mode to a certain extent in a frequency band slightly higher than the resonance frequency fr.

[0072] According to the first embodiment described above, the first electrode finger 9B has the first front end wide region 10B. The second electrode finger 9E has the second front end wide region 10D. The lengths of the plurality of first dummy electrodes 9C gradually decrease from one end to the other end of the first bus bar 9A. Therefore, it is possible to more reliably suppress the spurious of the transverse mode between the resonant frequency fr and the anti-resonant frequency fa.

[0073] The support substrate 3B is a polycrystalline substrate made of silicon, alumina, spinel or glass. Therefore, in the resonator 8 using the polycrystalline substrate, the spurious of the transverse mode between the resonance frequency fr and the antiresonance frequency fa can be suppressed more reliably.

[0074] In addition, the polycrystalline substrate as the support substrate 3B is C-axis oriented. Therefore, in the resonator 8 using the C-axis oriented polycrystalline substrate, the spurious of the transverse mode between the resonance frequency fr and the antiresonance frequency fa can be suppressed more reliably.

[0075] In addition, the low acoustic velocity layer 3C is disposed between the piezoelectric substrate 3A and the support substrate 3B. Therefore, in the resonator 8 including the low acoustic velocity layer 3C, it is possible to more reliably suppress spurious of the transverse mode between the resonance frequency fr and the antiresonance frequency fa.

[0076] In addition, the first electrode finger 9B has the first root-side wide region 10A. The second electrode finger 9E has the second root-side wide region 10C. Therefore, it is possible to more reliably suppress spurious in the transverse mode between the resonance frequency fr and the anti-resonance frequency fa.

[0077] In addition, the first root side wide region 10A is adjacent to the second front end side wide region 10D of the adjacent second electrode finger 9E. The second root side wide region 10C is adjacent to the first front end side wide region 10B of the adjacent first electrode finger 9B. Therefore, the spurious of the transverse mode between the resonance frequency fr and the anti-resonance frequency fa can be suppressed more reliably.

[0078] The lengths of the second dummy electrodes 9F are inversely correlated with the lengths of the first dummy electrodes 9C and gradually increase from one end to the other end of the second bus bar 9D. Therefore, spurious in the transverse mode between the resonance frequency fr and the antiresonance frequency fa can be more reliably suppressed.

[0079] In addition, in the first root side wide width region 10A, the first front end side wide width region 10B, the second root side wide width region 10C, and the second front end side wide width region 10D, the length L of the wide width region in the opening length direction is set to a length between 0.50λ and 1.75λ. Therefore, it is possible to more reliably suppress the spurious of the transverse mode between the resonance frequency fr and the anti-resonance frequency fa.

[0080] Furthermore, in at least one of the first root side wide width region 10A, the first front end side wide width region 10B, the second root side wide width region 10C, and the second front end side wide width region 10D, the length L in the opening length direction may be set to between 0.50λ and 1.75λ. In this case, the spurious of the transverse mode between the resonance frequency fr and the anti-resonance frequency fa can be suppressed to a certain extent.

[0081] For example, in the first root side wide width region 10A, the first front end side wide width region 10B, the second root side wide width region 10C, and the second front end side wide width region 10D, the width of the wide width region in the traveling direction of the elastic wave is set to W, and W is between 1.1 and 1.4 times the electrode finger width. Therefore, it is possible to more reliably suppress the spurious of the transverse mode between the resonance frequency fr and the anti-resonance frequency fa.

[0082] For example, in at least one of the first root side wide width region 10A, the first front end side wide width region 10B, the second root side wide width region 10C, and the second front end side wide width region 10D, the wide width region width in the traveling direction of the elastic wave may be set to W, where W is 1.1 to 1.4 times the electrode finger width. In this case, the spurious of the transverse mode between the resonance frequency fr and the anti-resonance frequency fa can be suppressed to a certain extent.

[0083] Implementation method 2.

[0084] Fig.10 FIG. 1 is a diagram showing an example of a resonator of an elastic wave device according to the second embodiment. Fig.11 yes Fig.10 1 is an enlarged view of the A part, the B part, the C part, and the D part of the embodiment 1. In addition, the same reference numerals are attached to the parts which are the same as or correspond to the parts of the embodiment 1, and the description of the parts is omitted.

[0085] like Fig.10 As shown, in the second embodiment, the first dummy electrode region Y1 and the second dummy electrode region Y2 are different from those in the first embodiment.

[0086] Specifically, if Fig.11 As shown, in Embodiment 2, when the wavelength of the surface acoustic wave is λ, the length of the uppermost first virtual electrode 9C is set to 2λ. The length of the lowermost first virtual electrode 9C is set to λ. The length of the uppermost second virtual electrode 9F is set to λ. The length of the lowermost second virtual electrode 9F is set to 2λ.

[0087] Next, use Fig.12 and Fig.13 , which explains the difference in characteristics caused by the different lengths of the virtual electrodes.

[0088] Fig.12 In the second embodiment, the resonator having the same inclined portion as the resonator of the elastic wave device in the bus bar and the same dummy electrode length and having no wide region and the characteristics of the comparative example. Fig.13 In the second embodiment, the resonator having a different inclined portion in the bus bar from the resonator of the elastic wave device, having a different dummy electrode length, and having no wide region and the characteristics of the comparative example. Fig.12 and Fig.13 The horizontal and vertical axes are Figure 5 same.

[0089] Fig.12 In the second embodiment, the resonator having the same inclined portion as the resonator of the elastic wave device in the bus bar and the same dummy electrode length and having no wide region and the characteristics of the comparative example.

[0090] exist Fig.12 In the figure, the solid line Z1 represents the characteristics of a resonator in Embodiment 2, which has the same inclined portion in the bus bar as the resonator 8 of the elastic wave device 1, has the same length of the virtual electrode, and does not have a wide area. In this resonator, the capacitance value, the number of pairs of electrode fingers, the opening length, and the duty ratio are the same as those corresponding to Figure 6 The dotted line Z2 is the characteristic of a comparative example in which the inclined portion of the busbar and the wide area of ​​the electrode finger are deleted from the resonator 8 of the elastic wave device 1 in the second embodiment. In this comparative example, the capacitance value, the number of pairs of electrode fingers, the opening length, and the duty ratio are the same as those corresponding to Figure 6 The same is true for the comparative example.

[0091] exist Fig.13 In the figure, the solid line Z1 represents the characteristics of a resonator having a different inclined portion in the bus bar from the resonator 8 of the elastic wave device 1, a different length of the virtual electrode, and no wide area in the embodiment 2. In the resonator 8, the capacitance value, the number of pairs of electrode fingers, the opening length, and the duty ratio are the same as those corresponding to Figure 6 The dotted line Z2 is the same as the resonator 8. Fig.12 The same as the dotted line Z2.

[0092] exist Fig.13 In (a), the length of the first dummy electrode 9C at the bottom is set to 0.25λ. The length of the second dummy electrode 9F at the top is set to 0.25λ. Fig.13 In (b), the length of the first dummy electrode 9C at the bottom is set to 0.50λ. The length of the second dummy electrode 9F at the top is set to 0.50λ. Fig.13 In (c), the length of the lowermost first dummy electrode 9C is set to 0.75λ. The length of the uppermost second dummy electrode 9F is set to 0.75λ.

[0093] like Fig.12 As shown, in the solid line Z1, the conductance value is suppressed from increasing locally in the frequency band slightly lower than the antiresonance frequency fa. This means that the spurious of the transverse mode of the resonator corresponding to the solid line Z1 is suppressed in the frequency band slightly lower than the antiresonance frequency fa.

[0094] like Fig.13 As shown, in the solid line Z1, the conductance value is suppressed from increasing locally in the frequency band slightly lower than the antiresonance frequency fa. This means that even in the resonator corresponding to the solid line Z1, the spurious of the transverse mode can be suppressed to a certain extent in the frequency band slightly lower than the antiresonance frequency fa.

[0095] According to the second embodiment described above, the length of the uppermost first virtual electrode 9C is set to 2λ. The length of the lowermost first virtual electrode 9C is set to λ. The length of the uppermost second virtual electrode 9F is set to λ. The length of the lowermost second virtual electrode 9F is set to 2λ. Therefore, it is possible to more reliably suppress the spurious between the resonant frequency fr and the anti-resonant frequency fa.

[0096] The length of the virtual electrode connected to the other end of the first bus bar 9A is between 0.125 and 0.500 times the length of the virtual electrode connected to one end of the first bus bar 9A; or the length of the virtual electrode connected to one end of the second bus bar 9D is between 0.125 and 0.500 times the length of the virtual electrode connected to the other end of the second bus bar 9D. In this case, the spurious between the resonant frequency fr and the anti-resonant frequency fa can also be suppressed to a certain extent.

[0097] Implementation 3

[0098] Fig.14 2 is a cross-sectional view of an elastic wave device in accordance with Embodiment 3 applied to a module. Parts identical or corresponding to those in Embodiment 1 are denoted by the same reference numerals, and descriptions of such parts are omitted.

[0099] exist Fig.14 In the embodiment, module 100 includes wiring substrate 101 , integrated circuit component 102 , elastic wave device 1 , inductor 103 , and sealing portion 104 .

[0100] Wiring substrate 101 is the same as wiring substrate 2 of Embodiment 1. Integrated circuit component 102 is mounted inside wiring substrate 101. Integrated circuit component 102 includes a switch circuit and a low noise amplifier. Elastic wave device 1 is mounted on the main surface of wiring substrate 101. Inductor 103 is mounted on the main surface of wiring substrate 101. Inductor 103 is used for impedance matching. For example, inductor 103 is an integrated passive device (IPD). Sealing portion 104 seals a plurality of electronic components including elastic wave device 1.

[0101] According to the third embodiment described above, module 100 includes elastic wave device 1. Therefore, module 100 including elastic wave device 1 that suppresses spurious in a transverse mode between resonance frequency fr and antiresonance frequency fa can be obtained.

[0102] Although some aspects of at least one embodiment have been described above, it should be understood that various changes, modifications and improvements may be easily conceived by those skilled in the art. The changes, modifications and improvements involved are intended to become part of this disclosure and are intended to be within the scope of this disclosure.

[0103] It should be understood that the implementation of the method and apparatus described herein is not limited to the details of the structure and arrangement of the components described in the above description or illustrated in the accompanying drawings. The method and apparatus may be implemented in other embodiments and implemented or performed in various ways. The specific implementation is for illustrative purposes only and is not intended to be limiting.

[0104] The expressions and terms used in this disclosure are for illustrative purposes only and should not be considered as limiting. The use of "includes," "having," "having," "comprising," and variations thereof as used herein means including the following listed items, and their equivalents and additional items.

[0105] The reference to "or" means that any terms described using "or" can be interpreted as indicating one, multiple, and all instances of the terms.

[0106] References to front, back, left, right, top, bottom, up, down, horizontal, vertical, inside and outside are for convenience of description. Such references do not mean that the constituent elements of the present disclosure are limited to any particular position or spatial orientation. Therefore, the above description and drawings are only for illustration.

Claims

1. An elastic wave device, characterized in that: have: Piezoelectric substrate; a supporting substrate bonded to the piezoelectric substrate; a resonator formed on the piezoelectric substrate on the side opposite to the support substrate, the resonator generating a main mode wave and a transverse mode wave when power is applied; The resonator comprises: First bus bar; a second bus bar, the second bus bar facing the first bus bar; a plurality of first electrode fingers, on the second bus bar side, the plurality of first electrode fingers being connected to the first bus bar; A plurality of second electrode fingers, on the first bus bar side, the plurality of second electrode fingers being connected to the second bus bar; a plurality of first virtual electrodes, on the second bus bar side, the plurality of first virtual electrodes are connected to the first bus bar and face the plurality of second electrode fingers; A plurality of second virtual electrodes, on the first bus bar side, the plurality of second virtual electrodes are connected to the second 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 wide region, The front end portions of the plurality of second electrode fingers have a second front end wide region, The plurality of first dummy electrodes gradually become shorter from one end portion to the other end portion of the first bus bar.

2. The elastic wave device according to claim 1, characterized in that: The support substrate is a polycrystalline substrate formed of silicon, alumina, spinel or glass.

3. The elastic wave device according to claim 2, characterized in that: The polycrystalline substrate is C-axis oriented.

4. The elastic wave device according to claim 1, characterized in that: Also includes: A low acoustic velocity layer is disposed between the piezoelectric substrate and the supporting substrate.

5. The elastic wave device according to claim 1, characterized in that: The root portions of the plurality of first electrode fingers have a first root-side wide region, and the root portions of the plurality of second electrode fingers have a second root-side wide region.

6. The elastic wave device according to claim 5, characterized in that: In the plurality of first electrode fingers, the first root side wide region is adjacent to the second front end side wide region of an adjacent second electrode finger, and in the plurality of second electrode fingers, the second root side wide region is adjacent to the first front end side wide region of an adjacent first electrode finger.

7. The elastic wave device according to claim 1, characterized in that: The lengths of the plurality of second dummy electrodes are inversely correlated with the lengths of the plurality of first dummy electrodes, and gradually become longer from one end to the other end of the second bus bar.

8. The elastic wave device according to claim 1, characterized in that: In the opening length direction, the length of the wide region of the plurality of first electrode fingers or the length of the wide region of the plurality of second electrode fingers is set to be between 0.50λ and 1.75λ.

9. The elastic wave device according to claim 1, characterized in that: In the propagation direction of the elastic wave, the width of the wide regions of the plurality of first electrode fingers or the width of the wide regions of the plurality of second electrode fingers is set to be between 1.1 times and 1.4 times the electrode finger width.

10. The elastic wave device according to claim 1, wherein: The length of the virtual electrode connected to the other end of the first bus bar is between 0.125 and 0.500 times the length of the virtual electrode connected to one end of the first bus bar; or The length of the dummy electrode connected to one end of the second bus bar is between 0.125 times and 0.500 times the length of the dummy electrode connected to the other end of the second bus bar.

11. A module, characterized in that: have: The elastic wave device according to any one of claims 1 to 10.

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