Elastic wave device and module including the same

Abstract

An elastic wave device includes a piezoelectric substrate, a first bus bar having a plurality of electrode fingers formed on the piezoelectric substrate, and a second bus bar having a plurality of electrode fingers formed on the piezoelectric substrate and arranged opposite to the first bus bar. A recess is formed in a region of the piezoelectric substrate where the front end portions of the electrode fingers of the first bus bar and the second bus bar face each other. Thus, an elastic wave device in which spurious resonance is sufficiently suppressed and a module having the elastic wave device can be provided.

Description

Technical Field

[0001] This disclosure relates to an elastic wave device, a module comprising the elastic wave device, such as an elastic wave device having an elastic surface wave resonator, a filter, and a multiplexer. Background Technology

[0002] Patent document 1 (Japanese Patent Application Publication No. 2017-34363) illustrates an electronic component that can suppress parasitic resonance. Summary of the Invention

[0003] Patent Document 1 discloses an example of a technique for suppressing parasitic resonances caused by bulk waves by thinning the piezoelectric substrate.

[0004] However, the electronic components described in Patent Document 1 cannot suppress parasitic resonances caused by other reasons. Therefore, an elastic wave device that sufficiently suppresses parasitic resonances cannot be provided.

[0005] In view of the above-mentioned problems, the present disclosure aims to provide an elastic wave device that sufficiently suppresses parasitic resonances and a module having the elastic wave device.

[0006] According to one aspect of this disclosure, an elastic wave device is provided, comprising:

[0007] Piezoelectric substrate;

[0008] A first busbar having a plurality of electrode fingers formed on the piezoelectric substrate; and

[0009] A second bus having a plurality of electrode fingers formed on the piezoelectric substrate and arranged opposite to the first bus.

[0010] A recess is formed in the region of the piezoelectric substrate where the front ends of the electrode fingers of the first busbar and the second busbar are opposite to each other.

[0011] In one embodiment of this disclosure, a recess is formed in the region of the piezoelectric substrate where the front ends of the electrode fingers of the second busbar and the first busbar are opposite to each other.

[0012] In one embodiment of this disclosure, the recess is closer to the tip of the electrode finger of the second bus than the first bus of the piezoelectric substrate.

[0013] In one embodiment of this disclosure, the width of the recess in a direction parallel to the transmission direction of the elastic surface wave is in the range of 1 / 4 to 3 / 4 of the wavelength of the elastic surface wave.

[0014] In one embodiment of this disclosure, the depth of the recess is in the range of 35% to 100% of the thickness of the piezoelectric substrate.

[0015] In one embodiment of this disclosure, the piezoelectric substrate is made of lithium tantalate, lithium niobate, or crystal.

[0016] In one embodiment of this disclosure, the piezoelectric substrate is bonded to a support substrate made of sapphire, silicon, alumina, spinel, crystal, glass, or silicon.

[0017] In one embodiment of this disclosure, the recess is formed through the piezoelectric substrate, and the supporting substrate constitutes the bottom of the recess.

[0018] In one embodiment of this disclosure, a second recess is formed in the region of the piezoelectric substrate adjacent to the electrode finger at the end of the first bus or the electrode finger at the end of the second bus.

[0019] In one embodiment of this disclosure, the second recess is formed at both ends of the first busbar and the second busbar.

[0020] According to another aspect of this disclosure, a module comprising the aforementioned elastic wave device is also provided.

[0021] The beneficial effects of the present invention are as follows: According to this disclosure, an elastic wave device that sufficiently suppresses parasitic resonance and a module having the elastic wave device can be provided. Attached Figure Description

[0022] Figure 1 This is a longitudinal cross-sectional view of the elastic wave device in embodiment 1.

[0023] Figure 2 This is a diagram illustrating the elastic wave component of the elastic wave device in Embodiment 1.

[0024] Figure 3 This is a diagram illustrating the simulation conditions of the elastic wave device in embodiment 1.

[0025] Figure 4 This is a diagram illustrating the simulation conditions of the elastic wave device in embodiment 1.

[0026] Figure 5 This is a diagram showing the resonance characteristics of the elastic wave device of Embodiment 1 and the comparative example.

[0027] Figure 6 This is a diagram showing the resonance characteristics of the elastic wave device of Embodiment 1 and the comparative example.

[0028] Figure 7 This is a diagram showing the resonance characteristics of the elastic wave device of Embodiment 1 and the comparative example.

[0029] Figure 8 This is a diagram showing the resonance characteristics of the elastic wave device of Embodiment 1 and the comparative example.

[0030] Figure 9 This is a diagram showing the resonance characteristics of the elastic wave device of Embodiment 1 and the comparative example.

[0031] Figure 10 This is a diagram showing an example of the elastic wave component of the elastic wave device in embodiment 2.

[0032] Figure 11 This is a longitudinal cross-sectional view of the module of the elastic wave device using embodiment 3. Detailed Implementation

[0033] The specific embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that similar or identical parts in the figures are referred to by the same reference numerals. Repeated descriptions of the similar or identical parts will be simplified or omitted.

[0034] Implementation Form 1

[0035] Figure 1 This is a longitudinal cross-sectional view of the elastic wave device in embodiment 1.

[0036] Figure 1 This is an example of an elastic wave device 1 for a duplexer.

[0037] like Figure 1 As shown, the elastic wave device 1 has a wiring substrate 3, several external connection terminals 31, several electrode pads 9, several bumps 15, a device chip 5, and a sealing part 17.

[0038] The wiring substrate 3 is, for example, a multilayer substrate made of resin. The wiring substrate 3 is, for example, a low-temperature co-fired ceramic (LTCC) multilayer substrate made of multiple dielectric layers.

[0039] Several external connection terminals 31 are formed on the lower surface of the wiring substrate 3.

[0040] Several electrode pads 9 are formed on the main surface of the wiring substrate 3. The electrode pads 9 are made of, for example, copper and copper-containing alloys. The thickness of the electrode pads 9 is, for example, between 10 μm and 20 μm.

[0041] Several bumps 15 are formed on the upper surface of several electrode pads 9. The bumps 15 are, for example, gold bumps. The height of the bumps 15 is, for example, between 10 μm and 50 μm.

[0042] Device chip 5 may be a substrate made of piezoelectric single crystal such as lithium tantalate, lithium niobate, or quartz. Device chip 5 may also be a substrate made of piezoelectric ceramic. Alternatively, device chip 5 may be a substrate formed by bonding a piezoelectric substrate and a support substrate. The support substrate may be a substrate made of sapphire, silicon, alumina, spinel, quartz, or glass.

[0043] Device chip 5 is mounted on wiring substrate 3 via bumps 15 using flip-chip bonding technology. Device chip 5 is electrically connected to several electrode pads 9 through several bumps 15.

[0044] Device chip 5 is a substrate on which functional components are formed. For example, a transmitting filter and a receiving filter are formed on the main surface of device chip 5.

[0045] Transmitting filters are formed in a way that allows electronic signals in the desired frequency band to pass through. For example, a transmitting filter is a ladder filter composed of multiple series resonators and multiple parallel resonators.

[0046] A receiver filter is formed in a way that allows electronic signals in the desired frequency band to pass through. For example, a receiver filter is a ladder filter.

[0047] The sealing portion 17 is formed in a manner that covers the device chip 5. For example, the sealing portion 17 may be made of an insulator such as synthetic resin. Or, for example, the sealing portion 17 may be made of metal.

[0048] When the sealing part 17 is made of synthetic resin, the synthetic resin can be epoxy resin, polyimide, etc. Preferably, the sealing part 17 can be epoxy resin, and it is epoxy resin formed by a low-temperature curing process.

[0049] Next, using Figure 2 An example illustrating the elastic wave component 52 formed on the device chip 5. Figure 2 This is a diagram illustrating the elastic wave component of the elastic wave device in Embodiment 1.

[0050] like Figure 2 As shown, the elastic wave component 52 includes an IDT (Interdigital Transducer) 52a and a pair of reflectors 52b formed on the main surface of the device chip 5. The IDT (Interdigital Transducer) 52a and the pair of reflectors 52b are used to excite elastic surface waves (mainly SH waves).

[0051] The IDT 52a and the pair of reflectors 52b are made, for example, of an alloy of aluminum and copper. The IDT 52a and the pair of reflectors 52b are made, for example, of a suitable metal such as titanium, palladium, or silver, or an alloy of said metals. The IDT 52a and the pair of reflectors 52b are formed as a laminated metal film consisting of several layers of metal. The thickness of the IDT 52a and the pair of reflectors 52b is, for example, 150 nm to 450 nm.

[0052] IDT 52a has a pair of comb-shaped electrodes 52c. The pair of comb-shaped electrodes 52c are opposite to each other. Each comb-shaped electrode 52c has several electrode fingers 52d and a bus 52e (including a first bus 52e1 and a second bus 52e2). The electrode fingers 52d of each comb-shaped electrode 52c are arranged in a consistent manner in the length direction, and the bus 52e connects the electrode fingers 52d.

[0053] One of a pair of reflectors 52b is adjacent to one side of IDT 52a. The other of a pair of reflectors 52b is adjacent to the other side of IDT 52a.

[0054] A recessed Hole 1 is formed in the region of the device chip 5 where the front ends of the electrode fingers 52d of the first busbar 52e1 and the second busbar 52e2 are opposite to each other. A recessed Hole 2 is also formed in the region of the device chip 5 where the front ends of the electrode fingers 52d of the second busbar 52e2 and the first busbar 52e1 are opposite to each other.

[0055] Several recessed Hole1 and several recessed Hole2 can be formed. Furthermore, recessed Hole1 can be formed as the tip of the electrode finger 52d closer to the first busbar 52e2 than the first busbar 52e1. Similarly, recessed Hole2 can be formed as the tip of the electrode finger 52d closer to the first busbar 52e1 than the second busbar 52e2. This allows for more effective suppression of parasitic resonances.

[0056] Hole1 and Hole2 can be formed during the wafer fabrication process, for example, using dry etching or wet etching.

[0057] Next, the results of the review of the elastic wave component 52 in this embodiment will be explained. The inventors simulated the resonance characteristics of the elastic wave component 52 in this embodiment under the following conditions. Figure 3 and Figure 4 This is a diagram that schematically illustrates the conditions under which these simulations are performed.

[0058] like Figure 3 As shown, the support substrate is made of sapphire, and its thickness is considered to be infinite.

[0059] like Figure 3As shown, the piezoelectric substrate LT is a single-crystal lithium tantalate substrate that is Y-cut by 42° rotation and X-transfer, with a thickness of 0.7 wavelength λ.

[0060] The wavelength λ is set to 4.2 μm.

[0061] like Figure 3 As shown, the thickness of IDT 52a is set to 420nm.

[0062] The duty ratio is set to 50%.

[0063] The logarithm of IDT 52a is considered to be infinite.

[0064] like Figure 3 As shown, considering manufacturing conditions, the gap between the front end of DT and the recessed Hole (including recessed Hole1 and recessed Hole2) is set to 500nm.

[0065] like Figure 3 As shown, the distance from the recessed Hole end on one side of the front end of IDT 52a to the busbar 52e is set to twice the wavelength, which is 2λ.

[0066] like Figure 3 As shown, simulations were performed for the concave depth HoleHeight being set to 0.25 times (0.25λ), 0.5 times (0.5λ), and 0.7 times (0.7λ) of the wavelength.

[0067] like Figure 4 As shown, the aperture length (Aperture) is set to 10 times the wavelength, which is 10λ.

[0068] like Figure 4 As shown, the length of the concave Hole in the direction perpendicular to the transmission direction of the elastic surface wave is set to 2 μm.

[0069] like Figure 4 As shown, simulations were performed for cases where the width HoleW of the concave Hole in the direction parallel to the propagation direction of the elastic surface wave was set to 50%, 75%, 100%, 125%, and 150% of the pitch. Furthermore, the pitch is equivalent to half the wavelength λ.

[0070] The results of the above simulation are explained below.

[0071] Figure 5These are diagrams showing the resonance characteristics of the elastic wave assembly 52 of this embodiment and the comparative example. (a) is a diagram showing the resonance characteristics of the comparative example ref without the recessed Hole. (b) is a diagram showing the resonance characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a Hole W of 50% and a Hole Height of 0.25 times the wavelength (0.25λ) is provided between the front ends of all IDTs 52a and the corresponding busbars 52e1 and 52e2. (c) is a diagram showing the resonance characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a Hole W of 50% and a Hole Height of 0.5 times the wavelength (0.5λ) is provided between the front ends of all IDTs 52a and the corresponding busbars 52e1 and 52e2. (d) is a diagram showing the resonant characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a HoleW of 50% and a HoleHeight of 0.7 times the wavelength (0.7λ) is provided between the front end of all IDT 52a and the corresponding busbars 52e1, 52e2.

[0072] like Figure 5 As shown, compared to the comparative example, it can be seen that the resonance characteristics of the elastic wave component 52 in this embodiment can suppress parasitic resonance. Furthermore, it can be seen that when HoleW is 50%, the larger the absolute value of the depth HoleHeight, the better the parasitic resonance is suppressed.

[0073] Figure 6 These are diagrams showing the resonance characteristics of the elastic wave assembly 52 of this embodiment and the comparative example. (a) is a diagram showing the resonance characteristics of the comparative example ref without the recessed Hole. (b) is a diagram showing the resonance characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a Hole W of 75% and a Hole Height of 0.25 times the wavelength (0.25λ) is provided between the front ends of all IDTs 52a and the corresponding busbars 52e1 and 52e2. (c) is a diagram showing the resonance characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a Hole W of 75% and a Hole Height of 0.5 times the wavelength (0.5λ) is provided between the front ends of all IDTs 52a and the corresponding busbars 52e1 and 52e2. (d) is a diagram showing the resonant characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a HoleW of 75% and a HoleHeight of 0.7 times the wavelength (0.7λ) is provided between the front end of all IDT 52a and the corresponding busbars 52e1, 52e2.

[0074] like Figure 6As shown, compared with the comparative example, it can be seen that the resonance characteristics of the elastic wave component 52 in this embodiment can suppress parasitic resonance. Furthermore, with HoleW at 75%, the correlation between the absolute value of depth HoleHeight and the degree to which parasitic resonance is suppressed is unclear.

[0075] Figure 7 These are diagrams showing the resonance characteristics of the elastic wave assembly 52 of this embodiment and the comparative example. (a) is a diagram showing the resonance characteristics of the comparative example ref without the recessed Hole. (b) is a diagram showing the resonance characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a Hole W of 100% and a Hole Height of 0.25 times the wavelength (0.25λ) is provided between the front ends of all IDTs 52a and the corresponding busbars 52e1 and 52e2. (c) is a diagram showing the resonance characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a Hole W of 100% and a Hole Height of 0.5 times the wavelength (0.5λ) is provided between the front ends of all IDTs 52a and the corresponding busbars 52e1 and 52e2. (d) is a diagram showing the resonant characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a HoleW of 100% and a HoleHeight of a multiple of the wavelength (0.7λ) is provided between the front end of all IDT 52a and the corresponding busbars 52e1, 52e2.

[0076] like Figure 7 As shown, compared with the comparative example, it can be seen that the resonance characteristics of the elastic wave component 52 in this embodiment can suppress parasitic resonance. In addition, when HoleW is 100%, the smaller the absolute value of the depth HoleHeight, the better the parasitic resonance is suppressed.

[0077] Figure 8These are diagrams showing the resonance characteristics of the elastic wave assembly 52 of this embodiment and the comparative example. (a) is a diagram showing the resonance characteristics of the comparative example ref without the recessed Hole. (b) is a diagram showing the resonance characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a Hole W of 125% and a Hole Height of 0.25 times the wavelength (0.25λ) is provided between the front end of all IDTs 52a and the corresponding busbars 52e1 and 52e2. (c) is a diagram showing the resonance characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a Hole W of 125% and a Hole Height of 0.5 times the wavelength (0.5λ) is provided between the front end of all IDTs 52a and the corresponding busbars 52e1 and 52e2. (d) is a diagram showing the resonant characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a HoleW of 125% and a HoleHeight of 0.7 times the wavelength (0.7λ) is provided between the front end of all IDT 52a and the corresponding busbars 52e1, 52e2.

[0078] like Figure 8 As shown, compared with the comparative example, it can be seen that the resonance characteristics of the elastic wave component 52 in this embodiment can suppress parasitic resonance. In addition, when HoleW is 125%, the smaller the absolute value of the depth HoleHeight, the better the parasitic resonance is suppressed.

[0079] Figure 9 These are diagrams showing the resonance characteristics of the elastic wave assembly 52 of this embodiment and the comparative example. (a) is a diagram showing the resonance characteristics of the comparative example ref without the recessed Hole. (b) is a diagram showing the resonance characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a Hole W of 150% and a Hole Height of 0.25 times the wavelength (0.25λ) is provided between the front ends of all IDTs 52a and the corresponding busbars 52e1 and 52e2. (c) is a diagram showing the resonance characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a Hole W of 150% and a Hole Height of 0.5 times the wavelength (0.5λ) is provided between the front ends of all IDTs 52a and the corresponding busbars 52e1 and 52e2. (d) is a diagram showing the resonant characteristics of the elastic wave assembly 52 of this embodiment, wherein a recessed Hole with a HoleW of 150% and a HoleHeight of 0.7 times the wavelength (0.7λ) is provided between the front end of all IDT 52a and the corresponding busbars 52e1, 52e2.

[0080] like Figure 9As shown, compared with the comparative example, it can be seen that the resonance characteristics of the elastic wave component 52 in this embodiment can suppress parasitic resonance. Furthermore, when HoleW is 150%, the correlation between the absolute value of depth HoleHeight and the degree to which parasitic resonance is suppressed is unclear.

[0081] According to Embodiment 1 described above, a recess Hole 1 is formed in the region of the piezoelectric substrate where the front ends of the electrode fingers 52d of the first busbar 52e1 and the second busbar 52e2 face each other. Therefore, an elastic wave device for suppressing parasitic resonance can be provided.

[0082] Furthermore, a recessed Hole2 is formed in the region of the piezoelectric substrate where the front ends of the electrode fingers 52d of the second busbar 52e2 and the first busbar 52e1 face each other. Therefore, an elastic wave device that better suppresses parasitic resonance can be provided.

[0083] In addition, the recessed Hole1 is formed to be closer to the front end of the electrode finger 52d of the second busbar 52e2 than the first busbar 52e1, thus providing a more effective elastic wave device to suppress parasitic resonance.

[0084] Furthermore, by making the width of the recessed Hole in the direction parallel to the transmission direction of the elastic surface wave within the range of 1 / 4 to 3 / 4 of the wavelength λ of the elastic surface wave, an elastic wave device that can better suppress parasitic resonances can be provided.

[0085] In addition, the depth of the recessed Hole (HoleHeight) is in the range of 35% to 100% of the thickness of the piezoelectric substrate LT, thus providing an elastic wave device that can better suppress parasitic resonances.

[0086] In addition, the substrate of the device chip 5 is bonded to a support substrate made of sapphire, silicon, alumina, spinel, crystal, glass and silicon, thus providing an elastic wave device with better temperature characteristics.

[0087] Implementation Form 2

[0088] Figure 10 This is a diagram illustrating the elastic wave assembly of the elastic wave device in Embodiment 2. Furthermore, the same reference numerals are used for parts similar to or identical to those in Embodiment 1. Descriptions of these similar or identical parts will be omitted.

[0089] like Figure 10As shown, a recessed Hole 3 is formed in the region of the piezoelectric substrate LT adjacent to the electrode finger 52d at the end of the first busbar 52e1 or the electrode finger 52 at the end of the second busbar 52e2. That is, recessed Holes 3 are formed on both sides of the IDT 52a. In this embodiment, no reflector is formed. Instead, the phenomenon of elastic waves reflecting off the end face of the device chip 5 is used to replace the reflector. This eliminates the space required for a reflector. Therefore, miniaturization of the elastic wave device can be achieved. Furthermore, since the recessed Hole 3 can be formed simultaneously with the recessed Hole 1 and recessed Hole 2, the manufacturing process and development cycle of the elastic wave device are not increased.

[0090] Since other constructions are the same as in Embodiment 1, the description is omitted.

[0091] Implementation Form 3

[0092] Figure 11 This is a longitudinal cross-sectional view of the module of the elastic wave device applicable to Embodiment 3. Furthermore, the same reference numerals are used for parts similar to or identical to those in Embodiment 1, and descriptions of these similar or identical parts will be omitted.

[0093] exist Figure 11 In the module 100, there are wiring board 130, several external connection terminals 131, integrated circuit component IC, elastic wave device 1, inductor 111, and sealing part 117.

[0094] Wiring substrate 130 is equivalent to wiring substrate 3 in embodiment 1.

[0095] Several external connection terminals 31 are formed on the lower surface of the wiring substrate 130. Several external connection terminals 131 are mounted on the motherboard of a pre-designed mobile communication terminal.

[0096] Although not shown in the figure, the integrated circuit component IC is mounted inside the wiring substrate 130. The integrated circuit component IC includes switching circuitry and a low-noise amplifier.

[0097] The elastic wave device 1 is mounted on the main surface of the wiring substrate 130.

[0098] Inductor 111 is mounted on the main surface of the wiring substrate 130. Inductor 111 is mounted for impedance matching. Inductor 111 is, for example, an integrated passive device (IPD).

[0099] The sealing part 117 seals several electronic components of the elastic wave device 1.

[0100] According to embodiment 3 described above, module 100 includes elastic wave device 1. Therefore, a more compact module with excellent isolation characteristics can be provided.

[0101] While at least one embodiment has been described above, it should be understood that various changes, modifications, or improvements will readily occur to those skilled in the art. These changes, modifications, or improvements are also part of this disclosure and fall within the scope of this invention.

[0102] It should be understood that the embodiments of the methods or apparatus described herein are not limited to the architecture and arrangement of the constituent components described above or illustrated in the accompanying drawings. The methods and apparatus can be installed or performed in other embodiments.

[0103] The embodiments described are for illustrative purposes only and are not intended to be limiting.

[0104] The descriptions or terms used here are for illustrative purposes only and are not intended to be limiting. The use of "including," "possessing," "having," "comprise," and their variations here means to include the items listed below, their equivalents, and additional items.

[0105] The word “or”, or any word used in a description, may be interpreted as one, more than one, or all of the descriptive words.

[0106] The references to front, back, left, right, top, bottom, upper, lower, and horizontal and vertical are for ease of description and are not intended to limit the position and spatial configuration of any component in this invention. Therefore, the above description and drawings are merely exemplary.

Claims

1. An elastic wave device, characterized in that: The elastic wave device includes: Piezoelectric substrate; A first busbar having a plurality of electrode fingers formed on the piezoelectric substrate; and A second bus having a plurality of electrode fingers formed on the piezoelectric substrate and arranged opposite to the first bus. A recess is formed in the region of the piezoelectric substrate where the front ends of the electrode fingers of the first busbar and the second busbar are opposite to each other; The width of the recess in the direction parallel to the transmission direction of the elastic surface wave is in the range of 1 / 4 to 3 / 4 of the wavelength of the elastic surface wave.

2. The elastic wave device according to claim 1, characterized in that: A recess is formed in the region of the piezoelectric substrate where the front ends of the electrode fingers of the second busbar and the first busbar are opposite to each other.

3. The elastic wave device according to claim 1, characterized in that: The recess is closer to the tip of the electrode finger of the second bus than the first bus of the piezoelectric substrate.

4. The elastic wave device according to claim 1, characterized in that: The depth of the recess is in the range of 35% to 100% of the thickness of the piezoelectric substrate.

5. The elastic wave device according to claim 1, characterized in that: The piezoelectric substrate is made of lithium tantalate, lithium niobate, or crystal.

6. The elastic wave device according to claim 1, characterized in that: The piezoelectric substrate is bonded to a support substrate made of sapphire, silicon, alumina, spinel, crystal, glass, or silicon.

7. The elastic wave device according to claim 6, characterized in that: The recess is formed through the piezoelectric substrate, and the supporting substrate forms the bottom of the recess.

8. The elastic wave device according to claim 1, characterized in that: A second recess is formed in the region of the piezoelectric substrate adjacent to the electrode finger at the end of the first bus or the electrode finger at the end of the second bus.

9. The elastic wave device according to claim 8, characterized in that: The second recess is formed at both ends of the first busbar and the second busbar.

10. A module, characterized in that: The device comprises the elastic wave device as described in any one of claims 1 to 9.

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