Elastic wave device and module using the same

Abstract

To provide an elastic wave device that is excellent in temperature characteristics and further restrained spurious emissions, and a method for manufacturing the same.SOLUTION: An elastic wave device includes a support substrate, a medium layer formed on the support substrate, a piezoelectric substrate formed on the medium layer, and a resonator including an IDT electrode formed on the piezoelectric substrate. The medium layer has first acoustic impedance regions each having a longitudinal direction and a traverse direction, and second acoustic impedance regions having an acoustic impedance which are different from the stripe-shaped first acoustic impedance regions, the second acoustic impedance region having a longitudinal direction and a transverse direction and being alternately arranged with the first acoustic impedance regions.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to an acoustic wave device and a module using the acoustic wave device, and more particularly to a surface acoustic wave device using SH waves, such as a filter, a duplexer, or a multiplexer. [Background technology]

[0002] 2. Description of the Related Art In high-frequency communication systems for mobile communication terminals, such as smartphones, high-frequency filters and the like are used to remove unnecessary signals outside the frequency band used for communication.

[0003] Acoustic wave devices having a surface acoustic wave (SAW) element, etc., are used in high frequency filters, etc. The SAW element is an element in which an IDT (Interdigital Transducer) having a pair of comb-shaped electrodes is formed on a piezoelectric substrate.

[0004] For example, a surface acoustic wave device is manufactured as follows. First, a multilayer film substrate is created by bonding a piezoelectric substrate that propagates acoustic waves to a support substrate that has a smaller thermal expansion coefficient than the piezoelectric substrate. Next, a large number of IDT electrodes are formed on the multilayer film substrate using photolithography technology, and the substrate is then cut to a specified size by dicing to form a surface acoustic wave device. In this manufacturing method, by using a multilayer film substrate, changes in size of the piezoelectric substrate when the temperature changes are suppressed by the support substrate, and the frequency characteristics of the acoustic wave device are stabilized.

[0005] For example, Patent Document 1 and other documents disclose that in order to improve the temperature characteristics of an acoustic wave device, a support substrate such as a sapphire substrate that has a high Young's modulus and a small linear expansion coefficient is bonded to a piezoelectric substrate to suppress expansion and contraction due to temperature changes. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2009-278610 A Summary of the Invention [Problem to be solved by the invention]

[0007] As disclosed in Patent Document 1, in order to improve the temperature characteristics of an acoustic wave device, it is known to bond a support substrate such as a sapphire substrate, which has a high Young's modulus and a small linear expansion coefficient, to a piezoelectric substrate to suppress expansion and contraction due to temperature changes. However, resonators using such a support substrate have spurious emissions, especially on the high frequency side, and have poor filter characteristics.

[0008] The present disclosure has been made to solve the above-mentioned problems. An object of the present disclosure is to provide an acoustic wave device having good temperature characteristics and further suppressed spurious emissions, and a module using the acoustic wave device. [Means for solving the problem]

[0009] The acoustic wave device according to the present disclosure comprises: A support substrate; a medium layer formed on the support substrate; a piezoelectric substrate formed on the medium layer; a resonator including an IDT electrode formed on the piezoelectric substrate; Equipped with The medium layer is A first acoustic impedance region having a stripe shape with a longitudinal direction and a lateral direction; The acoustic wave device has a striped second acoustic impedance region having a different acoustic impedance from the first acoustic impedance region, the second acoustic impedance region being arranged alternately with the first acoustic impedance region and having a longitudinal direction and a lateral direction.

[0010] In one embodiment of the present disclosure, the longitudinal direction of the first acoustic impedance region and the second acoustic impedance region is arranged in the same direction as the longitudinal direction of electrode fingers of the IDT electrode.

[0011] According to one aspect of the present disclosure, the first acoustic impedance region and the second acoustic impedance region are arranged at a pitch different from an electrode pitch of the IDT electrode.

[0012] In one embodiment of the present disclosure, the thickness of the piezoelectric substrate is 0.4λ or more and 1.0λ or less, where λ is the wavelength of an elastic wave determined by the electrode pitch of the IDT electrodes.

[0013] In one embodiment of the present disclosure, the thickness of the medium layer is not less than 0.1 λ and not more than 0.5 λ, where λ is the wavelength of an acoustic wave determined by the electrode pitch of the IDT electrodes.

[0014] One aspect of the present invention is that, in a cross-sectional view of the first acoustic impedance region and the second acoustic impedance region in the short direction, the first acoustic impedance region and the second acoustic impedance region are arranged in three periods within an area in which four electrode fingers of the IDT electrode are arranged.

[0015] One embodiment of the present invention is that, in a cross-sectional view of the first acoustic impedance region and the second acoustic impedance region in the short direction, the first acoustic impedance region and the second acoustic impedance region are arranged in five to six periods within a range in which eight electrode fingers of the IDT electrode are arranged.

[0016] In one aspect of the present invention, the first acoustic impedance region is made of silicon dioxide.

[0017] In one aspect of the present invention, the second acoustic impedance region is made of alumina, aluminum nitride, silicon nitride, silicon oxynitride, silicon or silicon carbide.

[0018] In one aspect of the present invention, the support substrate is made of sapphire, silicon, alumina, spinel, quartz crystal or glass.

[0019] A module including the acoustic wave device is one aspect of the present invention. Effect of the Invention

[0020] According to the present disclosure, it is possible to provide an acoustic wave device having good temperature characteristics and further suppressed spurious emissions, and a method for manufacturing the same. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a cross-sectional view of an acoustic wave device 1 according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing the device chip 5 of the acoustic wave device 1 according to the first embodiment. [Diagram 3] FIG. 3 is a top view of the functional element 50 of the acoustic wave device 1 according to the first embodiment. [Figure 4] FIG. 4 is a diagram illustrating the resonance characteristics of the acoustic wave device 1 according to the first embodiment and the resonator of a comparative example. [Diagram 5] FIG. 5 is a second diagram illustrating the resonance characteristics of the acoustic wave device 1 according to the first embodiment and the resonator of a comparative example. [Figure 6] FIG. 6 is a diagram illustrating resonance characteristics of the resonator (five periods in a range of eight electrode fingers, etc.) of the acoustic wave device 1 according to the first embodiment. [Figure 7] FIG. 7 is a diagram illustrating resonance characteristics of the resonator (six periods in a range of eight electrode fingers, etc.) of the acoustic wave device 1 according to the first embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing a configuration in which five second acoustic impedance regions 12B are arranged within the range of eight electrode fingers 51b. [Figure 9] FIG. 9 is a top view of the functional element 50 of the acoustic wave device 1 according to the second embodiment. [Figure 10] FIG. 10 is a diagram illustrating a method for manufacturing the acoustic wave device 1. As shown in FIG. [Figure 11]FIG. 11 is a diagram for explaining a manufacturing method of the acoustic wave device 1 according to the second embodiment. [Figure 12] FIG. 12 is a vertical cross-sectional view of a module to which the acoustic wave device 1 according to the first to third embodiments is applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The embodiments will be described with reference to the accompanying drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals. Duplicate descriptions of the parts will be appropriately simplified or omitted.

[0023] Embodiment 1 FIG. 1 is a cross-sectional view of an acoustic wave device 1 according to a first embodiment.

[0024] As shown in FIG. 1, the acoustic wave device 1 includes a wiring substrate 3, an external connection terminal 31, a device chip 5, electrode pads 9, bumps 15, and a sealing portion 17.

[0025] For example, the wiring board 3 is a multi-layer board made of resin, or a low temperature co-fired ceramics (LTCC) multi-layer board made of a plurality of dielectric layers.

[0026] A plurality of external connection terminals 31 are formed on the lower surface of the wiring board 3 .

[0027] A plurality of electrode pads 9 are formed on the main surface of the wiring board 3. For example, the electrode pads 9 are made of copper or an alloy containing copper. For example, the thickness of the electrode pads 9 is 10 μm to 20 μm.

[0028] The bumps 15 are formed on the upper surface of each of the electrode pads 9. For example, the bumps 15 are gold bumps. For example, the height of the bumps 15 is 10 μm to 50 μm.

[0029] A gap 16 is formed between the wiring board 3 and the device chip 5 .

[0030] The device chip 5 is mounted on the wiring board 3 by flip-chip bonding via the bumps 15. The device chip 5 is electrically connected to the plurality of electrode pads 9 via the plurality of bumps 15.

[0031] The device chip 5 is a substrate on which the acoustic wave elements 50 are formed. For example, on the main surface of the device chip 5, a transmission filter and a reception filter including a plurality of acoustic wave elements 50, which are mainly resonators, are formed.

[0032] The transmit filter is formed so as to pass electrical signals in a desired frequency band, and is, for example, a ladder-type filter made up of a plurality of series resonators and a plurality of parallel resonators.

[0033] The receive filter is configured to pass electrical signals in a desired frequency band, and is, for example, a ladder filter.

[0034] The sealing portion 17 is formed so as to cover the device chip 5. For example, the sealing portion 17 is made of an insulating material such as a synthetic resin. For example, the sealing portion 17 is made of a metal.

[0035] When the sealing portion 17 is made of a synthetic resin, the synthetic resin is an epoxy resin, a polyimide, etc. Preferably, the sealing portion 17 is made of an epoxy resin and is formed of the epoxy resin using a low temperature curing process.

[0036] FIG. 2 is a cross-sectional view showing the device chip 5 of the acoustic wave device 1 according to the first embodiment.

[0037] 2, the device chip 5 includes a piezoelectric substrate 11, a medium layer 12, and a support substrate 13. On the piezoelectric substrate 11, an acoustic wave element 50 is formed.

[0038] The piezoelectric substrate 11 is, for example, a substrate made of a piezoelectric single crystal such as lithium tantalate, lithium niobate, or quartz crystal. In another example, the piezoelectric substrate 11 is a substrate made of a piezoelectric ceramic.

[0039] The thickness of the piezoelectric substrate 11 can be set to, for example, 0.3 μm to 5 μm.

[0040] The medium layer 12 includes a first acoustic impedance region 12A and a second acoustic impedance region 12B. The first acoustic impedance region 12A is made of, for example, silicon nitride, silicon oxynitride, silicon, alumina, silicon dioxide, or silicon carbide. The second acoustic impedance region 12B is made of, for example, alumina, aluminum nitride, silicon nitride, silicon oxynitride, silicon, or silicon carbide, and is made of a material different from that used in the first acoustic impedance region 12A.

[0041] The thickness of medium layer 12 may be, for example, 0.5 μm to 2 μm.

[0042] 2, first acoustic impedance regions 12A and second acoustic impedance regions 12B are arranged at three periods with respect to four electrode fingers 51b on piezoelectric substrate 11. In other words, three second acoustic impedance regions 12B are arranged within the range of four electrode fingers 51b. In other words, first acoustic impedance regions 12A and second acoustic impedance regions 12B are arranged at a pitch different from the pitch of electrode fingers 51b.

[0043] 2, second acoustic impedance region 12B may be formed to penetrate first acoustic impedance region 12A. That is, medium layer 12 may be formed so that second acoustic impedance region 12B is exposed on both the piezoelectric substrate 11 side and the support substrate 13 side. Second acoustic impedance region 12B may be formed to have a thickness equal to or greater than half the thickness of medium layer 12.

[0044] According to another example, medium layer 12 may be formed such that second acoustic impedance region 12B is not exposed on the piezoelectric substrate 11 side.

[0045] In another example, medium layer 12 may be formed such that second acoustic impedance region 12B is not exposed on the supporting substrate 13 side.

[0046] The support substrate 13 can be formed of, for example, sapphire, silicon, alumina, spinel, silicon nitride, aluminum nitride, silicon carbide, silicon oxynitride, diamond, quartz, glass, etc. The support substrate 13 should have a small thermal expansion coefficient and a high Young's modulus. This is because the temperature characteristics of the acoustic wave device 1 are improved. A sapphire substrate, which is a typical substrate that satisfies these conditions, is hard and chemically stable, so that surface processing to have an uneven or jagged shape is difficult, resulting in a decrease in yield. Therefore, it is desirable for the support substrate 13 to have a flat, plate-like rectangular parallelepiped shape.

[0047] The thickness of the support substrate 13 can be, for example, from 50 μm to 200 μm.

[0048] Next, an example of an acoustic wave element 50 formed on a piezoelectric substrate 11 will be described with reference to Fig. 3. Fig. 3 is a top view of the functional element 50 of the acoustic wave device 1 according to the first embodiment.

[0049] 3 does not show the piezoelectric substrate 11 in a see-through manner for ease of explanation, an acoustic wave element 50 including an IDT (Interdigital Transducer) electrode 51 and a pair of reflectors 52 is formed on the main surface of the piezoelectric substrate 11 (see FIG. 2). The IDT electrode 51 and the pair of reflectors 52 are provided so as to be able to excite acoustic waves (mainly SH waves).

[0050] For example, the IDT electrode 51 and the pair of reflectors 52 are formed of an alloy of aluminum and copper, or an appropriate metal such as aluminum, molybdenum, iridium, tungsten, cobalt, nickel, ruthenium, chromium, strontium, titanium, palladium, or silver, or an alloy thereof.

[0051] For example, the IDT electrode 51 and the pair of reflectors 52 are formed of a laminated metal film in which a plurality of metal layers are laminated. For example, the thickness of the IDT electrode 51 and the pair of reflectors 52 is 150 nm to 450 nm.

[0052] The IDT electrode 51 includes a pair of comb-shaped electrodes 51a that face each other. The comb-shaped electrodes 51a include a plurality of electrode fingers 51b and a bus bar 51c.

[0053] The electrode fingers 51b are arranged with their longitudinal directions aligned. The bus bar 51c connects the electrode fingers 51b together.

[0054] One of the pair of reflectors 52 is adjacent to one side of the IDT electrode 51. The other of the pair of reflectors 52 is adjacent to the other side of the IDT electrode 51.

[0055] A medium layer 12 is formed between a piezoelectric substrate 11 and a support substrate 13 (not shown in FIG. 3). As shown in FIG. 3, first acoustic impedance region 12A and second acoustic impedance region 12B each form a stripe-shaped region having a longitudinal direction and a lateral direction. As shown in FIG. 3, first acoustic impedance region 12A and second acoustic impedance region 12B are alternately arranged in the lateral direction.

[0056] As shown in FIG. 3, the longitudinal direction of first acoustic impedance region 12A and second acoustic impedance region 12B is aligned in the same direction as the longitudinal direction of electrode finger 51b.

[0057] 4 is a diagram showing the resonance characteristics of the acoustic wave device 1 according to the first embodiment and a resonator of a comparative example. Lithium tantalate was used for the piezoelectric substrate 11. The thicknesses of the piezoelectric substrate 11 were calculated by setting the thicknesses to 0.4λ, 0.5λ, 0.6λ, 0.7λ, and 0.8, where λ is the wavelength of the acoustic wave determined by the pitch of the electrode fingers.

[0058] The thickness of medium layer 12 was 0.25λ. The widths in the short direction of first acoustic impedance region 12A and second acoustic impedance region 12B were the same, that is, the duty ratio was 50%. First acoustic impedance region 12A was made of silicon dioxide. Second acoustic impedance region 12B was made of alumina. Support substrate 13 was a sapphire substrate.

[0059] The comparative example has lithium tantalate with a thickness of 0.4λ formed on a sapphire substrate, and does not include medium layer 12. The comparative example is otherwise similar to the resonator of acoustic wave device 1 according to the first embodiment.

[0060] In FIG. 4, the peaks and valleys seen in the vicinity of 950 MHz to 1050 MHz are associated with the original resonance mode. The peaks and valleys that appear at higher frequencies, here in the vicinity of 1100 MHz to 1700 MHz, are based on non-original resonance modes and are called spurious. If there is a strong spurious, it will cause significant deterioration in characteristics when assembling resonators to configure a filter or the like, so it can be said that the smaller the height of the spurious peak and the depth of the spurious valley are, the better the characteristics will be. As shown in FIG. 4, the resonator of the acoustic wave device according to the first embodiment has a significantly improved spurious compared to the resonance characteristic LT0.4 / SA of the comparative example in any resonance characteristic 0.4λ to 0.8λ from the thickness of the piezoelectric substrate 11 of 0.4λ to 0.8λ.

[0061] 5 is a diagram (part 2) showing the resonance characteristics of the acoustic wave device 1 according to the first embodiment and a resonator of a comparative example. The thickness of the piezoelectric substrate 11 was set to 0.6λ. The thicknesses of the medium layer 12 were set to 0.05λ, 0.1λ, 0.25λ, and 0.5λ for calculation. The rest is as described in FIG. 4. The comparative example has lithium tantalate with a thickness of 0.6λ formed on a sapphire substrate and does not include the medium layer 12. The comparative example is otherwise similar to the resonator of the acoustic wave device 1 according to the first embodiment.

[0062] 5, the resonator of the acoustic wave device according to the first embodiment has improved spurious response compared to the comparative example, regardless of the thickness of medium layer 12. In particular, when the thickness of medium layer 12 is 0.1λ or more, the spurious response is significantly improved compared to the comparative example. Furthermore, when the thickness of medium layer 12 is 0.25λ and 0.5λ, the improvement in spurious response is even greater.

[0063] FIG. 6 is a diagram illustrating resonance characteristics of the resonator (five periods in a range of eight electrode fingers, etc.) of the acoustic wave device 1 according to the first embodiment.

[0064] The resonance characteristic 4λ / 4 is the resonance characteristic when first acoustic impedance regions 12A and second acoustic impedance regions 12B are arranged in four periods in a range where 4λ electrode fingers, i.e., eight electrode fingers 51b, are arranged. In other words, four second acoustic impedance regions 12B are arranged within the range where eight electrode fingers 51b are arranged.

[0065] The resonance characteristic 4λ / 5 is the resonance characteristic when the first acoustic impedance regions 12A and the second acoustic impedance regions 12B are arranged in five periods in a range where 4λ electrode fingers, i.e., eight electrode fingers 51b, are arranged. In other words, five second acoustic impedance regions 12B are arranged within the range of eight electrode fingers 51b. Fig. 8 is a cross-sectional view showing a configuration in which five second acoustic impedance regions 12B are arranged within the range of eight electrode fingers 51b.

[0066] The resonance characteristic 4λ / 7 is the resonance characteristic when the first acoustic impedance regions 12A and the second acoustic impedance regions 12B are arranged in seven periods for the 4λ electrode fingers, i.e., eight electrode fingers 51b. In other words, seven second acoustic impedance regions 12B are arranged within the range of the eight electrode fingers 51b.

[0067] FIG. 7 is a diagram illustrating resonance characteristics of the resonator (six periods in a range of eight electrode fingers, etc.) of the acoustic wave device 1 according to the first embodiment.

[0068] The resonance characteristic 4λ / 6 is the resonance characteristic when the first acoustic impedance regions 12A and the second acoustic impedance regions 12B are arranged in six periods in a range where 4λ electrode fingers, i.e., eight electrode fingers 51b, are arranged. In other words, six second acoustic impedance regions 12B are arranged within the range of eight electrode fingers 51b. In other words, three second acoustic impedance regions 12B are arranged within the range of four electrode fingers 51b. The resonance characteristics 4λ / 4 and 4λ / 7 are the same as those described in FIG. 6.

[0069] As shown in Figures 6 and 7, in the resonator of the acoustic wave device of embodiment 1, it can be seen that the spurious is significantly improved when the first acoustic impedance region 12A and the second acoustic impedance region 12B are arranged in five or six periods for eight electrode fingers 51b.

[0070] Here, results are shown for discrete conditions of 4, 5, 6, and 7 periods for first acoustic impedance region 12A and second acoustic impedance region 12B for eight electrode fingers, and among these, the results for 5 and 6 periods are shown to be good, but considering that the improvement effect is small when the ratio of the number of electrode fingers 51b to the number of second acoustic impedance regions 12B is close to 2 or 1, it is reasonably expected that good characteristics will also be obtained for a period between 5 and 6 periods, for example, 5.5 periods (16 electrode fingers and 11 second acoustic impedance regions 12B). In other words, the good region has a width.

[0071] According to the first embodiment described above, it is possible to provide an acoustic wave device having better temperature characteristics and in which spurious emissions are further suppressed.

[0072] Embodiment 2 Fig. 9 is a top view of the functional element 50 of the acoustic wave device 1 according to the second embodiment. As shown in Fig. 9, the longitudinal direction of the first acoustic impedance region 12A and the second acoustic impedance region 12B are arranged in a direction different from the longitudinal direction of the electrode fingers 51b. This arrangement generates an acoustic impedance difference in the transverse mode waves, making it possible to reduce the transverse mode spurious.

[0073] The other configuration is the same as in the first embodiment, so the description will be omitted.

[0074] According to the second embodiment described above, it is possible to provide an acoustic wave device in which high frequency spurious responses are suppressed and transverse mode spurious responses are reduced.

[0075] Next, a method for manufacturing the acoustic wave device 1 according to the first embodiment will be described below. Fig. 10 is a diagram for explaining a method for manufacturing the acoustic wave device 1 according to the first embodiment.

[0076] 10(a), a first acoustic impedance film is formed on a support substrate 13. Next, the first acoustic impedance film is patterned. For the patterning process, a suitable method such as a lift-off method or an etching method is selected depending on the material of the first acoustic impedance film.

[0077] As shown in Fig. 10(b), the area from which the first acoustic impedance film has been removed by the patterning process is filled with a second acoustic impedance material. The filling method for the second acoustic impedance material is selected from a variety of methods, such as a squeegee method, a vapor deposition method, and a sputtering method, depending on the material.

[0078] As shown in Fig. 10(c), the second acoustic impedance material is polished until the first acoustic impedance film is exposed. The polishing process may be performed by a chemical polishing method or a mechanical polishing method, depending on the material.

[0079] 10(d), after the polishing process, it is bonded to piezoelectric substrate 11. Acoustic wave element 50 is configured on piezoelectric substrate 11 so as to obtain desired device characteristics, and a packaging process is performed to obtain acoustic wave device 1 according to the first embodiment.

[0080] Next, a second method for manufacturing the acoustic wave device 1 will be described. FIG 11 is a diagram for explaining the second method for manufacturing the acoustic wave device 1.

[0081] 11(a), a second acoustic impedance film is formed on a support substrate 13. Next, the second acoustic impedance film is patterned. For the patterning process, a suitable method such as a lift-off method or an etching method is selected depending on the material of the second acoustic impedance film.

[0082] As shown in Fig. 11(b), the area from which the second acoustic impedance film has been removed by the patterning process is filled with the first acoustic impedance material. The filling method for the first acoustic impedance material is selected from a variety of methods, such as a squeegee method, a vapor deposition method, a sputtering method, and a pressing method, depending on the material.

[0083] As shown in Fig. 11(c), the first acoustic impedance material is polished. The polishing may be continued until the first acoustic impedance film is exposed, or may not be continued until the first acoustic impedance film is exposed. The polishing process may be performed by a chemical polishing method or a mechanical polishing method, depending on the material.

[0084] 11(d), after a polishing process, it is bonded to a piezoelectric substrate 11. Acoustic wave element 50 is configured to obtain desired device characteristics, and a packaging process is performed to obtain acoustic wave device 1.

[0085] 12 is a vertical cross-sectional view of a module to which the acoustic wave device 1 according to the first to third embodiments is applied. Note that the same reference numerals are used to designate the same or corresponding parts as those in the first to third embodiments, and the description of these parts will be omitted.

[0086] 12, the module 100 includes a wiring board 130, a plurality of external connection terminals 131, an integrated circuit component IC, an acoustic wave device 1, an inductor 111, and a sealing portion 117.

[0087] A plurality of external connection terminals 31 are formed on the lower surface of the wiring board 130. The plurality of external connection terminals 131 are mounted on a motherboard of a preset mobile communication terminal.

[0088] For example, the integrated circuit component IC is mounted inside the wiring board 130. The integrated circuit component IC includes a switching circuit and a low-noise amplifier.

[0089] The acoustic wave device 1 is mounted on a main surface of a wiring board 130.

[0090] The inductor 111 is mounted on the main surface of the wiring board 130. The inductor 111 is mounted for impedance matching. For example, the inductor 111 is an Integrated Passive Device (IPD).

[0091] The sealing portion 117 seals a plurality of electronic components including the acoustic wave device 1 .

[0092] The module 100 described above includes the acoustic wave device 1. Therefore, it is possible to provide a module including an acoustic wave device that has better temperature characteristics and in which spurious emissions are further suppressed.

[0093] Having described several aspects of at least one embodiment, it should be understood that various alterations, modifications, and improvements will readily occur to those skilled in the art and are intended to be part of this disclosure, and are intended to be within the scope of this disclosure.

[0094] It is to be understood that the embodiments of the method and apparatus described herein are not limited in their application to the details of construction and the arrangement of components set forth in the above description or illustrated in the accompanying drawings, and the method and apparatus can be implemented in other embodiments and practiced or carried out in various ways.

[0095] The specific implementations are provided herein for illustrative purposes only and are not intended to be limiting.

[0096] The phraseology and terminology used in this disclosure are for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," "having," "including" and variations thereof herein means the inclusion of the items listed thereafter and equivalents thereof as well as additional items.

[0097] References to "or" may be construed as meaning that any term described using "or" refers to one, more than one, and all of those described terms.

[0098] All references to front, back, left, right, top, bottom, up, down, horizontal, vertical, front and back are intended for convenience of description. Such references are not intended to limit the components of this disclosure to any one positional or spatial orientation. Accordingly, the foregoing description and drawings are by way of example only. [Explanation of symbols]

[0099] 1 Acoustic wave device, 3 Wiring board, 5 Device chip, 17 Sealing part 11 Piezoelectric substrate, 12 Medium layer, 13 Support substrate, 50 Elastic wave element 12A First Acoustic Impedance Region 12B Second Acoustic Impedance Region 100 module, 111 inductor, 117 sealing portion, 130 wiring board

Claims

1. A support substrate; a medium layer formed on the support substrate; a piezoelectric substrate formed on the medium layer; a resonator including an IDT electrode formed on the piezoelectric substrate; Equipped with The medium layer is A first acoustic impedance region having a stripe shape having a longitudinal direction and a lateral direction; An acoustic wave device comprising: a second acoustic impedance region having a different acoustic impedance from the first acoustic impedance region, the second acoustic impedance region being striped and arranged alternately with the first acoustic impedance region in a longitudinal direction and a transverse direction.

2. The acoustic wave device according to claim 1 , wherein a longitudinal direction of the first acoustic impedance region and the second acoustic impedance region is arranged in the same direction as a longitudinal direction of electrode fingers of the IDT electrode.

3. The acoustic wave device according to claim 1 , wherein the first acoustic impedance region and the second acoustic impedance region are arranged at a pitch different from an electrode pitch of the IDT electrode.

4. The acoustic wave device according to claim 1 , wherein the thickness of the piezoelectric substrate is not less than 0.4λ and not more than 1.0λ, where λ is a wavelength of an acoustic wave determined by an electrode pitch of the IDT electrodes.

5. 2 . The acoustic wave device according to claim 1 , wherein the medium layer has a thickness of 0.1λ to 0.5λ, where λ is a wavelength of an acoustic wave determined by an electrode pitch of the IDT electrodes.

6. 2. The acoustic wave device according to claim 1, wherein in a cross-sectional view of the first acoustic impedance region and the second acoustic impedance region in the short direction, the first acoustic impedance region and the second acoustic impedance region are arranged in three periods in a range in which four electrode fingers of the IDT electrode are arranged.

7. 2. The acoustic wave device according to claim 1, wherein in a cross-sectional view of the first acoustic impedance region and the second acoustic impedance region in the short direction, the first acoustic impedance region and the second acoustic impedance region are arranged in five to six periods within a range in which eight electrode fingers of the IDT electrode are arranged.

8. The acoustic wave device of claim 1 , wherein the first acoustic impedance region is made of silicon dioxide.

9. The acoustic wave device of claim 1 , wherein the second acoustic impedance region is made of alumina, aluminum nitride, silicon nitride, silicon oxynitride, silicon, or silicon carbide.

10. 2. The acoustic wave device according to claim 1, wherein the support substrate is made of sapphire, silicon, alumina, spinel, quartz, or glass.

11. A module comprising an acoustic wave device according to claim 1 .

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