Elastic wave device

Abstract

The present invention provides an elastic wave device capable of suppressing the adhesion of a piezoelectric layer to a support member. The elastic wave device (10) of the present invention comprises: a piezoelectric substrate (12), including a support member (13) comprising a support substrate (16) and a piezoelectric layer (14) disposed on the support member (13); a functional electrode disposed on the piezoelectric layer (14); at least one support body; and a cover portion (25). One of the at least one support body is configured on the piezoelectric substrate (12) to surround the functional electrode, and the cover portion (25) is disposed on the support body. A first cavity portion (10a) is provided in the support member (13). The first cavity portion (10a) overlaps with at least a portion of the functional electrode when viewed from above. A second cavity portion (10b) is provided, surrounded by the piezoelectric substrate (12), the support body disposed between the piezoelectric substrate (12) and the cover portion (25), and the cover portion (25). When the direction in which the piezoelectric substrate (12), the support provided between the piezoelectric substrate (12) and the cover (25) are stacked is set as the height direction, and the dimension along the height direction is set as the height, the height of the first cavity (10a) is higher than the height of the second cavity (10b).

Description

Technical Field

[0001] This invention relates to elastic wave devices. Background Technology

[0002] Previously, elastic wave devices have been widely used in filters for portable telephones, etc. For example, the elastic wave device described in Patent Document 1 below includes a piezoelectric substrate, a support member disposed on the piezoelectric substrate, and a cover member disposed on the support member. In this elastic wave device, a hollow space is provided, which is surrounded by the piezoelectric substrate, the support member, and the cover member. An IDT (Interdigital Transducer) electrode is disposed on the piezoelectric substrate, facing the hollow space.

[0003] In Patent Document 2 described below, a recess is provided above the support member. A piezoelectric film is provided on the support member, covering the recess. That is, a hollow space is provided on the support member side. An IDT electrode is provided in the portion of the piezoelectric film covering the recess.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-278972

[0007] Patent Document 2: Japanese Patent Application Publication No. 2017-224890 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] In elastic wave devices such as those described in Patent Document 2, an encapsulation structure as described in Patent Document 1 is sometimes used. However, in such elastic wave devices, the piezoelectric film warps toward the hollow space side provided on the support member side, which may cause the piezoelectric film to stick to the support member.

[0010] The purpose of this invention is to provide an elastic wave device capable of suppressing the adhesion of a piezoelectric layer to a support member.

[0011] Technical solutions for solving the problem

[0012] The elastic wave device of the present invention comprises: a piezoelectric substrate, including a support member comprising a support substrate and a piezoelectric layer disposed on the support member; a functional electrode disposed on the piezoelectric layer; at least one support body; and a cover portion, wherein one of the at least one support bodies is configured on the piezoelectric substrate to surround the functional electrode, and the cover portion is disposed on the support body; a first cavity portion is disposed on the support member, the first cavity portion overlapping at least a portion of the functional electrode in plan view; a second cavity portion is disposed and surrounded by the piezoelectric substrate, the support body disposed between the piezoelectric substrate and the cover portion, and the cover portion; wherein the direction in which the piezoelectric substrate, the support body disposed between the piezoelectric substrate and the cover portion, and the cover portion are stacked is defined as the height direction; and when the dimension along the height direction is defined as the height, the height of the first cavity portion is higher than the height of the second cavity portion.

[0013] Invention Effects

[0014] According to the present invention, the adhesion of the piezoelectric layer to the support member can be suppressed. Attached Figure Description

[0015] Figure 1 This is a simplified front sectional view of the elastic wave device according to the first embodiment of the present invention.

[0016] Figure 2 This is a schematic top view showing the structure on a piezoelectric substrate of the elastic wave device according to the first embodiment of the present invention.

[0017] Figure 3 This illustrates a first variation of the first embodiment of the present invention, relating to an elastic wave device, and... Figure 1 A simplified sectional view of a significant portion.

[0018] Figure 4 This illustrates a second variation of the elastic wave device according to the first embodiment of the present invention, and... Figure 1 A simplified sectional view of a significant portion.

[0019] Figure 5 This is a schematic cross-sectional view showing the structure on a piezoelectric substrate of an elastic wave device according to a third variation of the first embodiment of the present invention.

[0020] Figure 6 This illustrates the elastic wave device according to the fourth variation of the first embodiment of the present invention, and... Figure 1 A significant portion of the simplified top view.

[0021] Figure 7 This is a simplified front sectional view of the elastic wave device according to the fifth variation of the first embodiment of the present invention.

[0022] Figure 8 This is a schematic top view showing the structure on a piezoelectric substrate of the elastic wave device according to the second embodiment of the present invention.

[0023] Figure 9 This is a schematic top view showing the structure on a piezoelectric substrate of an elastic wave device according to a first variation of the second embodiment of the present invention.

[0024] Figure 10 This is a schematic top view showing the structure on a piezoelectric substrate of an elastic wave device according to a second variation of the second embodiment of the present invention.

[0025] Figure 11 This is a schematic cross-sectional view showing the vicinity of the first support in the third embodiment of the present invention.

[0026] Figure 12 This is a schematic cross-sectional view showing the vicinity of the first support in a modified example of the third embodiment of the present invention.

[0027] Figure 13 This is a schematic cross-sectional view showing the first support and the vicinity of the third support in the fourth embodiment of the present invention.

[0028] Figure 14 This illustrates the elastic wave device according to the fifth embodiment of the present invention, and... Figure 1 A simplified sectional view of a significant portion.

[0029] Figure 15 This illustrates the elastic wave device according to the sixth embodiment of the present invention, and... Figure 1 The portion shown is a simplified sectional view of a corresponding part.

[0030] Figure 16 (a) is a simplified three-dimensional diagram showing the appearance of an elastic wave device utilizing a thickness shear mode for volume waves. Figure 16 (b) is a top view showing the electrode structure on the piezoelectric layer.

[0031] Figure 17 yes Figure 16 A sectional view of the portion along line AA in (a).

[0032] Figure 18 (a) is a schematic front sectional view illustrating the propagation of a Lamb wave in a piezoelectric film of an elastic wave device. Figure 18 (b) is a schematic front sectional view of a bulk wave used to illustrate the thickness shear mode of propagation of a piezoelectric film in an elastic wave device.

[0033] Figure 19This is a diagram showing the amplitude direction of the body wave in the thickness shear mode.

[0034] Figure 20 This is a diagram showing the resonant characteristics of an elastic wave device utilizing a thickness shear mode for body waves.

[0035] Figure 21 This is a graph showing the relationship between d / p and the relative bandwidth of the resonator when the center-to-center distance between adjacent electrodes is set to p and the thickness of the piezoelectric layer is set to d.

[0036] Figure 22 This is a top view of an elastic wave device that utilizes the thickness shear mode of body waves.

[0037] Figure 23 This is a diagram showing the resonant characteristics of an elastic wave device with stray emissions, representing a reference example.

[0038] Figure 24 This is a graph showing the relationship between the relative bandwidth and the phase rotation of the spurious impedance, which is normalized by 180 degrees as the size of the spurious.

[0039] Figure 25 This is a graph showing the relationship between d / 2p and the metallization ratio MR.

[0040] Figure 26 This is a diagram showing the mapping of the relative bandwidth to the Euler angles (0°, θ, ψ) of LiNbO3 when d / p is infinitely close to 0.

[0041] Figure 27 This is a partially cut-off three-dimensional diagram used to illustrate an elastic wave device utilizing Lamb waves. Detailed Implementation

[0042] Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings, thereby clarifying the present invention.

[0043] Furthermore, it should be noted in advance that the embodiments described in this specification are illustrative, and partial substitutions or combinations of structures can be made between different embodiments.

[0044] Figure 1 This is a simplified front sectional view of the elastic wave device according to the first embodiment of the present invention. Figure 2 This is a schematic top view showing the structure on a piezoelectric substrate of the elastic wave device according to the first embodiment. Figure 1 In the diagram, a simplified representation of a rectangle with two diagonals is used to illustrate the IDT electrode described later. Figure 1 The same applies to simplified sectional views other than those shown in the diagram. Figure 2 The dielectric film, described later, is omitted from this text. Figure 2The same applies in the schematic top view, excluding other examples. Additionally, Figure 1 It is shown in a simplified diagram. Figure 2 A sectional view of the portion along line II.

[0045] like Figure 1 As shown, the elastic wave device 10 has a piezoelectric substrate 12 and an IDT electrode 11 as a functional electrode. The piezoelectric substrate 12 has a support member 13 and a piezoelectric layer 14. In this embodiment, the support member 13 includes a support substrate 16 and an intermediate layer 15. The intermediate layer 15 is provided on the support substrate 16. The piezoelectric layer 14 is provided on the intermediate layer 15. However, the support member 13 may also be composed only of the support substrate 16.

[0046] The piezoelectric layer 14 has a first main surface 14a and a second main surface 14b. The first main surface 14a and the second main surface 14b are opposite to each other. The second main surface 14b is located on the side of the support member 13.

[0047] For example, semiconductors such as silicon and ceramics such as alumina can be used as the material for the support substrate 16. Suitable dielectrics such as silicon oxide or tantalum pentoxide can be used as the material for the intermediate layer 15. For example, lithium niobate, lithium tantalate, zinc oxide, aluminum nitride, quartz, or PZT (lead zirconate titanate) can be used as the material for the piezoelectric layer 14. Furthermore, the piezoelectric layer 14 is preferably a lithium tantalate layer such as a LiTaO3 layer or a lithium niobate layer such as a LiNbO3 layer.

[0048] A first cavity 10a is provided in the support member 13. More specifically, a recess is provided in the intermediate layer 15. A piezoelectric layer 14 is provided on the intermediate layer 15 to block the recess. Thus, the first cavity 10a is formed. Alternatively, the first cavity 10a may be provided in both the intermediate layer 15 and the support substrate 16, or it may be provided only in the support substrate 16. As long as at least one first cavity 10a is provided in the support member 13, it is sufficient.

[0049] like Figure 2 As shown, a plurality of IDT electrodes 11 are provided on the first main surface 14a of the piezoelectric layer 14. This constitutes a plurality of elastic wave resonators. The elastic wave device 10 in this embodiment is a filter device. Furthermore, the elastic wave device 10 only needs to have at least one IDT electrode 11. The elastic wave device of the present invention only needs to include at least one elastic wave resonator.

[0050] Viewed from above, at least a portion of the IDT electrode 11 overlaps with the first cavity 10a. More specifically, as Figure 2As shown, in this embodiment, a plurality of first void portions 10a are provided. In top view, the IDT electrode 11 of each elastic wave resonator overlaps with a single first void portion 10a. However, multiple IDT electrodes 11 may also overlap with the same first void portion 10a. In this specification, top view refers to a view from a perspective equivalent to... Figure 1 Viewed from above. Furthermore, "viewing from above" refers to viewing along the direction in which the first support 18 and the cover 25 are stacked, as described later. Additionally, in Figure 1 In, for example, the side of the piezoelectric layer 14 in the support substrate 16 and the piezoelectric layer 14 is on top.

[0051] A first support 18 and a plurality of second supports 19 are provided on the first main surface 14a of the piezoelectric layer 14. In this embodiment, the first support 18 and the second supports 19 are stacks of multiple metal layers. The first support 18 has a frame-like shape. On the other hand, the second supports 19 have a columnar shape. The first support 18 is configured to surround the plurality of IDT electrodes 11 and the plurality of second supports 19. More specifically, the first support 18 has an opening 18c. The plurality of IDT electrodes 11 and the plurality of second supports 19 are located within the opening 18c. In addition, it is sufficient to provide at least one second support 19.

[0052] like Figure 1 As shown, a frame-shaped electrode layer 17A is provided between the piezoelectric layer 14 and the first support 18. The electrode layer 17A, like the first support 18, surrounds a plurality of IDT electrodes 11 and a plurality of second supports 19 when viewed from above. However, the electrode layer 17A may be omitted. A cover portion 25 is provided on the first support 18 and the plurality of second supports 19 to block the opening 18c. Thus, a second cavity portion 10b is provided, surrounded by the piezoelectric substrate 12, the electrode layer 17A, the first support 18, and the cover portion 25. The plurality of IDT electrodes 11 and the plurality of second supports 19 are disposed within the second cavity portion 10b.

[0053] The characteristic of this embodiment is that, when the direction in which the piezoelectric substrate 12, the first support 18, and the cover 25 are stacked is defined as the height direction, and when the dimension along the height direction is defined as the height, the height of the first cavity 10a is higher than the height of the second cavity 10b. Therefore, even when the piezoelectric layer 14 is deformed in a convex shape from the second cavity 10b side to the first cavity 10a side, adhesion of the piezoelectric layer 14 to the support member 13 can be suppressed.

[0054] The structure of this embodiment will now be described in further detail.

[0055] like Figure 1As shown, a dielectric film 24 is provided on the piezoelectric substrate 12, covering the IDT electrode 11. This makes the IDT electrode 11 less prone to breakage. For example, silicon oxide, silicon nitride, or silicon oxynitride can be used for the dielectric film 24. When the dielectric film 24 contains silicon oxide, the frequency-temperature characteristics can be improved. On the other hand, when the dielectric film 24 contains silicon nitride or the like, it can be used as a frequency tuning film. Alternatively, the dielectric film 24 may not be provided.

[0056] Through-holes 20 are continuously provided in the piezoelectric layer 14 and the dielectric film 24. The through-holes 20 are configured to reach the first void portion 10a. The through-holes 20 are used to remove the sacrificial layer in the intermediate layer 15 during the manufacture of the elastic wave device 10. However, it is not necessary to provide through-holes 20.

[0057] The cover portion 25 includes a cover portion body 26, an insulating layer 27A, and an insulating layer 27B. The cover portion body 26 has a first main surface 26a and a second main surface 26b. The first main surface 26a and the second main surface 26b face each other. The second main surface 26b is located on the piezoelectric substrate 12 side. An insulating layer 27A is provided on the first main surface 26a. An insulating layer 27B is provided on the second main surface 26b. In this embodiment, the cover portion body 26 is mainly composed of silicon. The material of the cover portion body 26 is not limited to the above, but it is preferable to use a semiconductor such as silicon as the main component. In this specification, the term "main component" refers to a component that accounts for more than 50% by weight. On the other hand, the insulating layer 27A and the insulating layer 27B are, for example, silicon oxide layers.

[0058] A via electrode 21A, serving as a lower bump metal, is provided in the cover portion 25. More specifically, a through hole is provided in the cover portion 25. This through hole is configured to reach the second support body 19. The via electrode 21A is disposed within this through hole. One end of the via electrode 21A is connected to the second support body 19. An electrode pad 21B is provided, connecting to the other end of the via electrode 21A. In this embodiment, the via electrode 21A and the electrode pad 21B are integrally formed. However, the via electrode 21A and the electrode pad 21B can also be separate. A bump 22 is attached to the electrode pad 21B.

[0059] More specifically, an insulating layer 27A is provided, covering the vicinity of the outer periphery of the electrode pad 21B. A bump 22 is attached to the portion of the electrode pad 21B not covered by the insulating layer 27A. In this specification, the outer periphery refers to the outer periphery as viewed from above. Furthermore, the insulating layer 27A may also extend between the electrode pad 21B and the cover body 26. Moreover, the insulating layer 27A may also extend between the via electrode 21A and the cover body 26. The insulating layers 27A and 27B may also be integrally formed via a through-hole in the cover body 26.

[0060] like Figure 2 As shown, a plurality of wiring electrodes 23 are disposed on the piezoelectric substrate 12. A portion of the plurality of wiring electrodes 23 connects the IDT electrode 11 to each other. Another portion of the plurality of wiring electrodes 23 electrically connects the IDT electrode 11 and the second support 19. More specifically, as shown... Figure 1 As shown, a conductive film 17B is provided on the piezoelectric substrate 12. A second support 19 is provided on the conductive film 17B. Therefore, the wiring electrode 23 is electrically connected to the second support 19 via the conductive film 17B. Furthermore, a plurality of IDT electrodes 11 are electrically connected to the outside via the wiring electrode 23, the conductive film 17B, the second support 19, the via electrode 21A, the electrode pad 21B, and the bump 22. Alternatively, the plurality of second supports 19 may include a second support 19 that is not connected to the via electrode 21A.

[0061] The first support 18 has a first portion 18a and a second portion 18b. The first portion 18a is located on the cover 25 side, and the second portion 18b is located on the piezoelectric substrate 12 side. That is, the second portion 18b is located on the piezoelectric layer 14 side in the height direction compared to the first portion 18a. In this embodiment, the second portion 18b is a laminate. More specifically, the second portion 18b has a first layer 18d and a second layer 18e. On the other hand, the first portion 18a is a single-layer metal layer.

[0062] In the first support 18, the first layer 18d of the first part 18a and the second part 18b contains the same metal. The first part 18a and the first layer 18d are joined together. Thus, the first part 18a and the first layer 18d constitute the first integral part. On the other hand, the first layer 18d and the second layer 18e contain different metals.

[0063] Similar to the first support 18, the second support 19 has a first portion 19a and a second portion 19b. The first portion 19a is located on the cover 25 side, and the second portion 19b is located on the piezoelectric substrate 12 side. In this embodiment, the second portion 19b is a laminate. More specifically, the second portion 19b has a first layer 19d and a second layer 19e. On the other hand, the first portion 19a is a single-layer metal layer.

[0064] In the second support 19, the first layer 19d of the first part 19a and the second part 19b contains the same metal. The first part 19a and the first layer 19d are joined together. Thus, the first part 19a and the first layer 19d constitute the second integral part. On the other hand, the first layer 19d and the second layer 19e contain different metals.

[0065] Furthermore, while no explicit joint interface is provided in the first component, the joint interface is shown in each sectional view for convenience. The same applies to the second component.

[0066] The first integral part and the second integral part each contain, for example, Au. The second layer 18e of the second part 18b and the second layer 19e of the second part 19b of the first support body 18 and the second support body 19 respectively contain, for example, Al. In this specification, the term "a component contains a material" includes the case where there are trace amounts of impurities that do not degrade the electrical characteristics of the elastic wave device.

[0067] Furthermore, in the first support 18, the first layer 18d of the first part 18a and the second part 18b may not contain the same metal. Similarly, in the second support 19, the first layer 19d of the first part 19a and the second part 19b may not contain the same metal. The second part 18b and the second part 19b of each of the first support 18 and the second support 19 may not be laminates.

[0068] The preferred structure in this embodiment is shown below.

[0069] like Figure 1 As shown, the wiring electrode 23 is preferably provided throughout the piezoelectric layer 14, covering both the portion that overlaps with the first cavity 10a in plan view and the portion that does not overlap with the first cavity 10a in plan view. This suppresses warping of the piezoelectric layer 14 from the second cavity 10b side to the first cavity 10a side. Therefore, adhesion of the piezoelectric layer 14 to the support member 13 can be effectively suppressed.

[0070] The first portion 18a and the second portion 18b of the first support 18 preferably contain metals of different types. Similarly, the first portion 19a and the second portion 19b of the second support 19 preferably contain metals of different types. In these cases, stress is less likely to concentrate on the piezoelectric layer 14. Therefore, warping of the piezoelectric layer 14 from the second cavity 10b side to the first cavity 10a side can be suppressed. Therefore, adhesion of the piezoelectric layer 14 to the support member 13 can be further suppressed.

[0071] However, the first portion 18a and the second portion 18b of the first support 18 may not contain metals of different types. Similarly, the first portion 19a and the second portion 19b of the second support 19 may not contain metals of different types. In these cases, the piezoelectric layer 14 becomes prone to warping from the second void 10b side towards the first void 10a side, making the present invention particularly suitable.

[0072] like Figure 2 As shown, the area of ​​the second cavity 10b viewed from above is preferably larger than the area of ​​the first cavity 10a viewed from above. This reduces the vulnerability of the elastic wave device 10 without hindering the excitation of the elastic wave.

[0073] Furthermore, the area of ​​the first cavity 10a as viewed from above specifically refers to the total area of ​​the first cavity 10a as viewed from above. When multiple first cavities 10a are provided, the sum of the areas of the multiple first cavities 10a as viewed from above is the area of ​​the first cavity 10a as viewed from above.

[0074] On the other hand, the area of ​​the second cavity 10b as viewed from above is the area of ​​the portion surrounded by the first support 18 as viewed from above. Furthermore, in this embodiment, at least one second support 19 is provided in the portion surrounded by the first support 18. In this case, the area of ​​the second cavity 10b as viewed from above is the area obtained by subtracting the area of ​​the second support 19 as viewed from the area of ​​the portion surrounded by the first support 18 as viewed from above. Hereinafter, the areas of the first cavity 10a and the second cavity 10b as viewed from above will sometimes be described simply as areas.

[0075] The second support 19 is preferably configured so that it does not overlap with the first cavity 10a when viewed from above. This makes it possible to more reliably reduce the vulnerability of the portion where the second support 19 is provided.

[0076] The conductive film 17B and the wiring electrode 23 are preferably made of the same material. When the wiring electrode 23 is connected to the conductive film 17B, it is preferable that the conductive film 17B and the wiring electrode 23 are integrally formed. This improves productivity. Alternatively, the conductive film 17B may not be connected to the wiring electrode 23.

[0077] In addition, such as Figure 1 As shown, in the first embodiment, a first support 18 and a plurality of second supports 19 are disposed on the piezoelectric layer 14 in the piezoelectric substrate 12. However, at least a portion of the first support 18 may also be disposed on a portion of the piezoelectric substrate 12 where the piezoelectric layer 14 is not disposed. Similarly, at least a portion of the second supports 19 may also be disposed on a portion of the piezoelectric substrate 12 where the piezoelectric layer 14 is not disposed. For example, at least a portion of the first support 18 or the second support 19 may also be disposed on the intermediate layer 15 or the support substrate 16.

[0078] Hereinafter, the first to fourth modifications of the first embodiment are shown. The only differences between the first to fourth modifications and the first embodiment are the arrangement of the dielectric film, the arrangement of the IDT electrode, the arrangement of the second support, or the arrangement of the wiring electrode. Even in the first to fourth modifications, the adhesion of the piezoelectric layer to the support member can be suppressed. Moreover, the fragility of the elastic wave device can be reduced without hindering the excitation of the elastic wave.

[0079] exist Figure 3 In the first modified example shown, the dielectric film 24 is disposed on the second main surface 14b of the piezoelectric layer 14, but not on the first main surface 14a. The dielectric film 24 is located within the first void portion 10a. The dielectric film 24 may also be integrally disposed with the intermediate layer 15. Alternatively, the dielectric film 24 and the intermediate layer 15 may also be disposed separately.

[0080] exist Figure 4 In the second variation shown, the dielectric film 24 is disposed on both the first main surface 14a and the second main surface 14b of the piezoelectric layer 14. Preferably, at least a portion of the dielectric film 24 is disposed on at least one of the first main surface 14a and the second main surface 14b of the piezoelectric layer 14, in a portion that overlaps with the first void 10a when viewed from above. In this case, the present invention is particularly suitable because the piezoelectric layer 14 becomes more prone to warping from the second void 10b side to the first void 10a side.

[0081] exist Figure 5 In the third modified example shown, the IDT electrode 11 is disposed on the second main surface 14b of the piezoelectric layer 14. The dielectric film 24 is disposed on the second main surface 14b, such that it covers the IDT electrode 11.

[0082] exist Figure 6 In the fourth variation shown, at least one pair of second supports 19 are configured to sandwich the IDT electrode 11. In this case, the present invention is particularly suitable because the piezoelectric layer 14 becomes more prone to warping from the second cavity 10b side to the first cavity 10a side. Moreover, the heat generated by the IDT electrode 11 can be released to the outside via at least one pair of second supports 19. Therefore, heat dissipation can be improved.

[0083] like Figure 6 As shown, preferably at least one second support 19 is disposed between the first support 18 and the IDT electrode 11. In this case, the second support 19 is not sandwiched between multiple IDT electrodes 11. Therefore, the heat generated by one IDT electrode 11 can be efficiently dissipated via the second support 19. This structure is suitable for situations where the power handling capability of the IDT electrode 11 is particularly important.

[0084] In the first embodiment, the cover body 26 is primarily composed of semiconductors. Furthermore, the cover 25 and the first support 18 are configured as separate units. Alternatively, the cover body 26 may also contain resin. For example, in… Figure 7 In the fifth variation of the first embodiment shown, the first support 18A and the cover body 26A are made of resin, and the first support 18A and the cover body 26A are integrally formed.

[0085] In other words, by providing a recess in the resin layer, the first support 18A and the cover body 26A are formed. This recess overlaps with the IDT electrode 11 when viewed from above. This recess is blocked by the piezoelectric layer 14. Thus, the second cavity is formed. Figure 7 The single-dot dashed line in the diagram is the boundary line between the first support body 18A and the cover body 26A.

[0086] Furthermore, an insulating layer 27A is provided on the cover body 26A in the same manner as in the first embodiment. On the other hand, in this modified example, the aforementioned insulating layer 27B is not provided. Furthermore, the second support is not provided. However, for example, at least one second support comprising resin may be integrally formed with the first support 18A and the cover body 26A. Alternatively, at least one second support may be provided in the same manner as in the first embodiment.

[0087] The via electrode 21A penetrates the cover body 26A and the first support 18A. Furthermore, one end of the via electrode 21A is connected to the conductive film 17C. The conductive film 17C comprises two metal layers. However, the conductive film 17C may also comprise a single metal layer, similar to the first embodiment.

[0088] Even in this modified example, the height of the first cavity 10a is greater than the height of the second cavity. Furthermore, the area of ​​the second cavity is larger than the area of ​​the first cavity 10a. Therefore, similar to the first embodiment, the adhesion of the piezoelectric layer 14 to the support member 13 can be suppressed. Moreover, the fragility of the elastic wave device can be reduced without hindering the excitation of the elastic wave.

[0089] The structures of the first to fifth modifications can also be applied to structures other than the first embodiment of the present invention.

[0090] Figure 8 This is a schematic top view showing the structure on the piezoelectric substrate of the elastic wave device according to the second embodiment.

[0091] The difference between this embodiment and the first embodiment lies in the arrangement of the second support 19, the IDT electrode 11, and the first cavity 10a, as well as the winding of the wiring. Another difference is the provision of a second support 39 with a different shape from the second support 19. Apart from the points mentioned above, the elastic wave device of this embodiment has the same structure as the elastic wave device 10 of the first embodiment.

[0092] The second support 39 has a wall-like shape. More specifically, the second support 39 has a rectangular shape when viewed from above. Alternatively, the wall-like shape of the second support 39 may simply include a portion of a shape extending in any one direction when viewed from above. The second support 39 may also include a curved portion when viewed from above.

[0093] In this embodiment, the second support 19, which has a columnar shape, is specifically cylindrical. However, the second support 19 may also be prismatic or the like.

[0094] The second support body in this invention can also have either a wall-like shape or a columnar shape. In the first embodiment, only a columnar second support body 19 is provided as the second support body. In this embodiment, both a wall-like second support body 39 and a columnar second support body 19 are provided as the second support body. On the other hand, only a wall-like second support body 39 may be provided as the second support body.

[0095] With the second support 39 having a wall-like shape, the cover portion can be supported more reliably. Therefore, for example, when the cover portion contains resin, the structure with the second support 39 is suitable.

[0096] Even in this embodiment, the height of the first cavity 10a is greater than the height of the second cavity 10b. Furthermore, the area of ​​the second cavity 10b is larger than the area of ​​the first cavity 10a. Therefore, similar to the first embodiment, adhesion of the piezoelectric layer 14 to the support member 13 can be suppressed. Moreover, the fragility of the elastic wave device can be reduced without hindering the excitation of the elastic wave.

[0097] In this embodiment, the second support 39 comprises a laminate of multiple metal layers. However, the second support 39 may also comprise resin. This example is illustrated by the following first and second modifications of the second embodiment. Even in the first and second modifications, as in the second embodiment, adhesion of the piezoelectric layer 14 to the support member 13 can be suppressed. Furthermore, the fragility of the elastic wave device can be reduced without hindering the excitation of the elastic wave.

[0098] exist Figure 9 In the first modified example shown, a second support 39A containing resin is provided on both wiring electrodes 23. More specifically, the second support 39A is provided from one wiring electrode 23 to the other wiring electrode 23 via the piezoelectric layer 14. The two wiring electrodes 23 are connected to different potentials. Even in this case, since the second support 39A contains resin, it is not easy to affect the electrical characteristics of the elastic wave device. Moreover, since a portion of the wiring electrode 23 can be used as the portion where the second support 39A is provided, miniaturization of the elastic wave device can be easily promoted.

[0099] exist Figure 10 In the second modified example shown, three second supports 39A are provided. One second support 39A is provided in the same manner as in the first modified example. The other two second supports 39A are provided on the same wiring electrode 23 and the piezoelectric layer 14, respectively.

[0100] In this modified example, viewed from above, a third cavity 30c is provided between two second supports 39A disposed on the same wiring electrode 23. The third cavity 30c is disposed on the support member 13 in the same manner as the first cavity 10a. The third cavity 30c is not connected to the first cavity 10a. The third cavity 30c is disposed independently.

[0101] Viewed from above, the third cavity 30c does not overlap with the IDT electrode 11. Viewed from above, the third cavity 30c overlaps with the wiring electrode 23. This makes it easier to reduce the parasitic capacitance of the wiring electrode 23.

[0102] On the other hand, when viewed from above, the third cavity 30c does not overlap with the second support 39A. Therefore, even in the section where the third cavity 30c is provided, the vulnerability can be reduced more reliably.

[0103] Figure 11 This is a schematic cross-sectional view showing the vicinity of the first support in the third embodiment.

[0104] The structure of the first support 48 in this embodiment differs from that in the first embodiment. Except for the points mentioned above, this embodiment has the same structure as the first embodiment. Therefore, in this embodiment, similar to the first embodiment, the height of the first cavity is higher than the height of the second cavity. Therefore, it is possible to suppress the adhesion of the piezoelectric layer to the support member.

[0105] In the first support 48, both the first part 48a and the second part 48b are laminated. Specifically, the first part 48a has a first layer 48g, a second layer 48h, and a third layer 48i. The second part 48b has a first layer 48d, a second layer 48e, and a third layer 48f. However, the number of layers in the first part 48a and the second part 48b may be two or more.

[0106] In part 1, 48a, layers 48g, 48h, and 48i are stacked in the order of first layer 48g, second layer 48h, and third layer 48i. First layer 48g is the part of part 1, 48a closest to second part 48b. Similarly, in part 2, 48b, layers 48d, 48e, and 48f are stacked in the order of first layer 48d, second layer 48e, and third layer 48f. First layer 48d is the part of part 2, 48b closest to first part 48a. The first body is formed by the first layer 48g and the first layer 48d of each part 1, 48a, and part 2, 48b.

[0107] Furthermore, similar to the first embodiment, the first support 48 has a frame-like shape. In this embodiment, the widths of the first layer 48g of the first portion 48a and the first layer 48d of the second portion 48b are different from each other. Therefore, in top view, the area of ​​the first layer 48g of the first portion 48a and the area of ​​the first layer 48d of the second portion 48b are different from each other. Furthermore, the width of each portion of the first support 48 is as follows: that is, the width is the dimension of each portion of the first support 48 along a direction orthogonal to both the direction in which the piezoelectric substrate 12, the first support 48, and the cover 25 are stacked and the direction in which the first support 48 extends on the piezoelectric substrate 12.

[0108] By having the above-described structure, the strength of the first support 48 can be more reliably improved. More specifically, during the manufacture of the elastic wave device, for example, a first portion 48a of the first support 48 is formed on the cover portion 25. On the other hand, a second portion 48b of the first support 48 is formed on the piezoelectric substrate 12. Then, the first portion 48a and the second portion 48b are joined together.

[0109] When joining the first portion 48a and the second portion 48b of the first support 48, positional misalignment sometimes occurs. In contrast, in this embodiment, the areas of the first portion 48a and the second portion 48b are different when viewed from above. Specifically, when viewed from above, the area of ​​the first layer 48g of the first portion 48a and the area of ​​the first layer 48d of the second portion 48b are different. This makes it easier to fix the joining area of ​​the first portion 48a and the second portion 48b.

[0110] More specifically, as long as there is another layer inside the outer periphery of the wider layer in the first layer 48g of part 1 48a and the first layer 48d of part 2 48b, the bonding area can be fixed even if a positional shift occurs. Therefore, the strength of the first support 48 can be improved more reliably. Furthermore, in the supports including the first and second supports in the embodiments described in this specification, a smaller layer exists inside the outer periphery of the layer with the larger area in a top view among adjacent layers.

[0111] Hereinafter, the area of ​​each part of the first support 48 as viewed from above will only be described as area. In the second part 48b, the area of ​​all layers other than the first layer 48d is larger than the area of ​​the first layer 48d. Therefore, the area of ​​the second layer 48e is larger than the area of ​​the first layer 48d. As a result, the entire portion of the first layer 48d can be easily formed on the second layer 48e. As a result, the planar accuracy of the first layer 48d can be improved. As a result, the bonding strength between the first part 48a and the second part 48b can be improved more reliably, and an airtight seal can be achieved more reliably. Moreover, even if no adhesive containing Sn or the like is provided between the first part 48a and the second part 48b, an airtight seal can be achieved more reliably. As a result, productivity can be effectively improved.

[0112] Similarly, even in part 48a, the area of ​​all layers other than layer 48g is larger than that of layer 48g. Therefore, the bonding strength between part 48a and part 48b can be further reliably improved, and an airtight seal can be achieved more reliably.

[0113] like Figure 11As shown, the further away the preferred layer is from the layers constituting the first integral part, the larger its area. More specifically, it is preferred that the area of ​​the third layer 48i of the first part 48a is larger than the area of ​​the second layer 48h, and the area of ​​the second layer 48h is larger than the area of ​​the first layer 48g. It is preferred that the area of ​​the third layer 48f of the second part 48b is larger than the area of ​​the second layer 48e, and the area of ​​the second layer 48e is larger than the area of ​​the first layer 48d. This allows for a more reliable improvement in the planar accuracy of the first layers 48g and 48d of both the first part 48a and the second part 48b. Therefore, it is possible to more reliably and effectively reduce the deviation in the bonding area between the first part 48a and the second part 48b.

[0114] The first component preferably contains Au. In this case, the resistance can be reduced.

[0115] One of the first part 48a and the second part 48b can also be a laminate. In this case, it is preferable that the part of the first part 48a and the second part 48b that constitutes the first joint has a smaller area and is a laminate. This reduces the joint area of ​​the first part 48a and the second part 48b, making it easier to miniaturize the elastic wave device.

[0116] Additionally, in Part 2, 48b, the area may be larger than the area of ​​at least one floor other than the area of ​​the first floor, 48d. The same applies to Part 1, 48a. Figure 12 In the modified example of the third embodiment shown, the area of ​​each layer of the second portion 48x increases in the order of the third layer 48f, the first layer 48j, and the second layer 48e. The first layer 48j is disposed on the third layer 48f, thereby covering the second layer 48e. Even in this case, the first layer 48j can be easily formed on the third layer 48f, and the portion of the first layer 48j located on the second layer 48e can improve planar accuracy. Moreover, even in this modified example, as in the third embodiment, the adhesion of the piezoelectric layer to the support member can be suppressed.

[0117] In this invention, at least one frame-shaped support, such as the first support 48, is sufficient. In the third embodiment, a structure of the first support 48 disposed between the piezoelectric substrate 12 and the cover portion 25 is shown. Alternatively, at least one frame-shaped support may include a support disposed between the support substrate and the piezoelectric layer. Hereinafter, the frame-shaped support disposed between the support substrate and the piezoelectric layer will be designated as the third support. An example in which the third support is constructed in the same manner as the first support 48 will be shown in the fourth embodiment.

[0118] Figure 13 This is a schematic cross-sectional view showing the first support and the vicinity of the third support in the fourth embodiment.

[0119] The difference between this embodiment and the third embodiment is that the support member 53 does not have an intermediate layer, but has a third support body 58. Apart from the points mentioned above, the elastic wave device of this embodiment has the same structure as the elastic wave device of the third embodiment.

[0120] A third support 58 is disposed on a support substrate 16. A piezoelectric layer 14 is disposed on the third support 58. The third support 58 has a frame-like shape. In this embodiment, the first cavity 50a is a cavity surrounded by the piezoelectric layer 14, the third support 58, and the support substrate 16. The height of the third support 58 is greater than the height of the first support 48. Therefore, even in this embodiment, the height of the first cavity 50a is greater than the height of the second cavity 10b. Therefore, adhesion of the piezoelectric layer 14 to the support member 53 can be suppressed.

[0121] Alternatively, the support member 53 may also have at least one fourth support body. In this case, the fourth support body is configured, for example, to overlap with the second support body as described above when viewed from above. The fourth support body is disposed on the support substrate 16. A piezoelectric layer is disposed on the fourth support body.

[0122] The third support 58 is constructed identically to the first support 48 except for its dimensions. Specifically, the third support 58 has a first portion 58a and a second portion 58b. The first portion 58a is located on the support substrate 16 side, and the second portion 58b is located on the piezoelectric layer 14 side. That is, the second portion 58b is located closer to the piezoelectric layer 14 in the height direction than the first portion 58a.

[0123] In the third support 58, both the first part 58a and the second part 58b are laminated. Specifically, the first part 58a has a first layer 58g, a second layer 58h, and a third layer 58i. The second part 58b has a first layer 58d, a second layer 58e, and a third layer 58f. However, the number of layers in the first part 58a and the second part 58b can be two or more.

[0124] In part 1, 58a, layers 1, 58g, 58h, and 58i are stacked in the order of layer 1, 58h, and 58i. Layer 1, 58g, is the part of part 1, 58a closest to part 2, 58b. Similarly, in part 2, 58b, layers 1, 58d, 58e, and 58f are stacked in the order of layer 1, 58e, and 58f. Layer 1, 58d, is the part of part 2, 58b closest to part 1, 58a. The first layer 58g and layer 58d of each of part 1, 58a, and part 2, 58b contain the same material. The first integral part is constituted by the first layer 58g and layer 58d of each of part 1, 58b.

[0125] Hereinafter, the area of ​​each part of the third support 58 as viewed from above will be described only as area. In the second part 58b, the area of ​​all layers other than the first layer 58d is larger than the area of ​​the first layer 58d. However, it is also possible that the area of ​​at least one layer other than the first layer 58d is larger than the area of ​​the first layer 58d. This improves the planar accuracy of the first layer 58d. Therefore, the joint strength of the first part 58a and the second part 58b can be improved more reliably, and an airtight seal can be achieved more reliably.

[0126] Similarly, even in part 1, 58a, the area of ​​all layers other than layer 58g is larger than the area of ​​layer 58g. However, it is also possible that the area of ​​at least one layer other than layer 58g is larger than the area of ​​layer 58g. This improves the planar accuracy of layer 58g.

[0127] The further away the preferred layer is from the layers constituting the first integral part, the larger its area. More specifically, it is preferred that the area of ​​the third layer 58i of the first part 58a is larger than the area of ​​the second layer 58h, and the area of ​​the second layer 58h is larger than the area of ​​the first layer 58g. It is preferred that the area of ​​the third layer 58f of the second part 58b is larger than the area of ​​the second layer 58e, and the area of ​​the second layer 58e is larger than the area of ​​the first layer 58d. This allows for a more reliable improvement in the planar accuracy of the first layers 58g and 58d of both the first part 58a and the second part 58b. Therefore, it is possible to more reliably and effectively reduce the deviation in the bonding area between the first part 58a and the second part 58b.

[0128] One of the first part 58a and the second part 58b can also be a laminate. In this case, it is preferable that the part of the first part 58a and the second part 58b with the smaller area constituting the joint is a laminate. This reduces the joint area of ​​the first part 58a and the second part 58b, making it easier to miniaturize the elastic wave device.

[0129] The area of ​​the first cavity 50a can be made smaller than the area of ​​the second cavity 10b by adjusting the size and arrangement of the third support 58. Furthermore, when the fourth support is provided, the area of ​​the first cavity 50a is obtained by subtracting the area of ​​the fourth support from the area of ​​the portion surrounded by the third support 58 from the area of ​​the fourth support from the area of ​​the third support 58 viewed from above. For example, the area of ​​the first cavity 50a can be reduced by making the fourth support a wall-like shape. This reduces the vulnerability of the elastic wave device without hindering the excitation of the elastic wave.

[0130] However, it is sufficient that the height of the third support 58 is greater than the height of the first support 48. In a structure having both the first support 48 and the third support 58, the areas of the first cavity 50a and the second cavity 10b can also be the same. For example, the height of the third support 58 can be greater than the height of the first support 48 by the thickness of at least one layer in the third support 58 being greater than the thickness of at least one layer in the first support 48. Alternatively, the height of the third support 58 can be greater than the height of the first support 48 by the number of layers in the third support 58 being greater than the number of layers in the first support 48.

[0131] Alternatively, an intermediate layer containing a dielectric or the like may be provided between the support substrate 16 and the third support 58, or between the piezoelectric layer 14 and the third support 58. In this way, the support member 53 may also include an intermediate layer.

[0132] Figure 14 This illustrates the elastic wave device according to the fifth embodiment, and... Figure 1 A simplified sectional view of a significant portion.

[0133] The difference between this embodiment and the first embodiment lies in the structure of the second support 69. Another difference between this embodiment and the first embodiment is that... Figure 14 The second support 69 shown is not connected to the via electrode. Apart from the points mentioned above, the elastic wave device of this embodiment has the same structure as the elastic wave device 10 of the first embodiment.

[0134] Similar to the first embodiment, in the first support 18, a first integral part is formed by a first layer 18d consisting of a first portion 18a and a second portion 18b. In the second support 69, a second integral part is formed by a first layer 19d consisting of a first portion 19a and a second portion 19b.

[0135] In this embodiment, the width of the portion of the first layer 19d of the second integral part in one second support 69 is narrower than the width of the narrowest portion of the first integral part of the first support 18. In this way, it is sufficient that the width of at least a portion of the second integral part in at least one second support 69 is narrower than the width of the first integral part. This allows for easy miniaturization of the elastic wave device. Furthermore, the width of each portion of the second support 69 refers to the dimension of each portion of the second support 69 along a direction orthogonal to the direction in which the piezoelectric substrate 12, the second support 69, and the cover 25 are stacked.

[0136] The width of the portion of the second integral part that is narrower than the width of the first integral part is preferably 1 μm or more. This reduces the resistance of the second support 69, allowing it to be used as wiring. The width of the portion of the second integral part that is narrower than the width of the first integral part is preferably less than 16 μm. This allows for a more reliable miniaturization of the elastic wave device.

[0137] Even in this embodiment, similar to the first embodiment, the height of the first cavity 10a is higher than the height of the second cavity 10b. Therefore, it is possible to suppress the adhesion of the piezoelectric layer 14 to the support member 13.

[0138] In embodiments 1 to 5 or their variations, each elastic wave resonator is configured to utilize a thickness shear mode, such as a first-order thickness shear mode, as a bulk wave. Alternatively, each elastic wave resonator may be configured to utilize a plate wave, or it may be configured to utilize a bulk wave other than a thickness shear mode. Hereinafter, an example is shown where the elastic wave resonator is a BAW (Bulk Acoustic Wave) element.

[0139] Figure 15 This illustrates the elastic wave device according to the sixth embodiment, and... Figure 1 The portion shown is a simplified sectional view of a corresponding part.

[0140] The difference between this embodiment and the first embodiment is that the functional electrode has an upper electrode 71A and a lower electrode 71B. Another difference is that the dielectric film 24 is not provided in this embodiment. Apart from the points mentioned above, the elastic wave device 70 of this embodiment has the same structure as the elastic wave device 10 of the first embodiment.

[0141] An upper electrode 71A is disposed on the first main surface 14a of the piezoelectric layer 14. A lower electrode 71B is disposed on the second main surface 14b of the piezoelectric layer 14. The upper electrode 71A and the lower electrode 71B are positioned opposite each other, sandwiching the piezoelectric layer 14. The upper electrode 71A and the lower electrode 71B are connected to different potentials. The region where the upper electrode 71A and the lower electrode 71B are positioned opposite each other is the excitation region. By applying an alternating electric field between the upper electrode 71A and the lower electrode 71B, an elastic wave is excited in the excitation region.

[0142] In this embodiment, the conductive film 17B, the wiring electrode 23, and the upper electrode 71A are integrated. However, the conductive film 17B, the wiring electrode 23, and the upper electrode 71A can also be configured as separate components.

[0143] It can also be set to have Figure 1 The dielectric film 24 shown covers the upper electrode 71A or the lower electrode 71B, which serves as the excitation electrode. In this case, the upper electrode 71A or the lower electrode 71B is less likely to be damaged.

[0144] Even in this embodiment, similar to the first embodiment, the height of the first cavity 10a is higher than the height of the second cavity 10b. Therefore, even when the piezoelectric layer 14 is deformed in a convex shape from the second cavity 10b side to the first cavity 10a side, the adhesion of the piezoelectric layer 14 to the support member 13 can be suppressed.

[0145] The thickness shearing mode and plate wave details are described below. Furthermore, the aforementioned IDT electrode 11 has the structure of an IDT electrode as described later. The term "electrode" in IDT electrode corresponds to the electrode finger in this invention. The support member in the following examples corresponds to the support substrate in this invention.

[0146] Figure 16 (a) is a simplified three-dimensional diagram showing the appearance of an elastic wave device utilizing a thickness shear mode for volume waves. Figure 16 (b) is a top view showing the electrode structure on the piezoelectric layer. Figure 17 yes Figure 16 A sectional view of the portion along line AA in (a).

[0147] The elastic wave device 1 has a piezoelectric layer 2 comprising LiNbO3. The piezoelectric layer 2 may also comprise LiTaO3. The cutting angle of the LiNbO3 and LiTaO3 is Z-cut, but it can also be rotationally Y-cut or X-cut. The thickness of the piezoelectric layer 2 is not particularly limited, but for effectively exciting the thickness shear mode, it is preferably 40 nm or more and 1000 nm or less, more preferably 50 nm or more and 1000 nm or less. The piezoelectric layer 2 has a first main surface 2a and a second main surface 2b facing each other. An electrode 3 and an electrode 4 are provided on the first main surface 2a. Here, electrode 3 is an example of a "first electrode," and electrode 4 is an example of a "second electrode." Figure 16 (a) and Figure 16 In (b), multiple electrodes 3 are connected to the first busbar 5. Multiple electrodes 4 are connected to the second busbar 6. The multiple electrodes 3 and multiple electrodes 4 are interleaved and interlocked. Electrodes 3 and 4 have a rectangular shape and a length direction. Electrodes 3 and adjacent electrodes 4 are opposite each other in a direction orthogonal to this length direction. The length directions of electrodes 3 and 4, as well as the directions orthogonal to the length directions of electrodes 3 and 4, are all directions that intersect the thickness direction of the piezoelectric layer 2. Therefore, it can also be said that electrodes 3 and adjacent electrodes 4 are opposite each other in a direction that intersects the thickness direction of the piezoelectric layer 2. Furthermore, the length directions of electrodes 3 and 4 can also be... Figure 16 (a) and Figure 16 The directions shown in (b) that are orthogonal to the length directions of electrodes 3 and 4 are interchanged. That is, in Figure 16 (a) and Figure 16 In (b), electrodes 3 and 4 can also extend in the direction in which the first busbar 5 and the second busbar 6 extend. In this case, the first busbar 5 and the second busbar 6 are in... Figure 16 (a) and Figure 16In (b), the electrodes extend in the direction in which electrodes 3 and 4 extend. Furthermore, multiple pairs of adjacent structures, consisting of an electrode 3 connected to one potential and an electrode 4 connected to another potential, are provided in a direction orthogonal to the length direction of the electrodes 3 and 4. Here, "adjacent to electrodes 3 and 4" does not mean that electrodes 3 and 4 are in direct contact, but rather that they are arranged with a gap between them. Furthermore, when electrodes 3 and 4 are adjacent, no electrodes connected to the signal electrode or ground electrode, including other electrodes 3 and 4, are arranged between electrodes 3 and 4. The number of pairs does not need to be an integer; it can be 1.5 pairs, 2.5 pairs, etc. The center-to-center distance, i.e., the spacing, between electrodes 3 and 4 is preferably in the range of 1 μm or more and 10 μm or less. Furthermore, the width of electrodes 3 and 4, i.e., the dimension in the opposing direction of electrodes 3 and 4, is preferably in the range of 50 nm or more and 1000 nm or less, more preferably in the range of 150 nm or more and 1000 nm or less. Furthermore, the so-called center-to-center distance between electrodes 3 and 4 is the distance connecting the center of the dimension (width dimension) of electrode 3 in the direction orthogonal to the length direction of electrode 3 and the center of the dimension (width dimension) of electrode 4 in the direction orthogonal to the length direction of electrode 4.

[0148] Furthermore, in the elastic wave device 1, a Z-cut piezoelectric layer is used, so the direction orthogonal to the length direction of electrodes 3 and 4 becomes the direction orthogonal to the polarization direction of piezoelectric layer 2. This is not limited to cases where a piezoelectric material with a different cut angle is used as piezoelectric layer 2. Here, "orthogonal" is not limited to strictly orthogonal; it can also be approximately orthogonal (the angle between the direction orthogonal to the length direction of electrodes 3 and 4 and the polarization direction is, for example, within the range of 90° ± 10°).

[0149] On the second main surface 2b side of the piezoelectric layer 2, a support member 8 is stacked with an insulating layer 7 in between. The insulating layer 7 and the support member 8 have a frame-like shape, such as... Figure 17 As shown, it has through holes 7a and 8a. This forms a cavity 9. The cavity 9 is provided so as not to interfere with the vibration of the excitation region C of the piezoelectric layer 2. Therefore, the support member 8 is stacked on the second main surface 2b with the insulating layer 7 in a position that does not overlap with the portion where at least one pair of electrodes 3 and 4 are provided. Alternatively, the insulating layer 7 may not be provided. Therefore, the support member 8 can be stacked directly or indirectly on the second main surface 2b of the piezoelectric layer 2.

[0150] The insulating layer 7 comprises silicon oxide. However, in addition to silicon oxide, suitable insulating materials such as silicon oxynitride and bauxite can also be used. The support member 8 comprises Si. The orientation of the face of the piezoelectric layer 2 of Si can be (100), (110), or (111). It is preferable that the Si constituting the support member 8 has a high resistivity of 4 kΩcm or higher. However, suitable insulating materials or semiconductor materials can also be used to construct the support member 8.

[0151] For example, materials used as supporting components 8 can include piezoelectric materials such as alumina, lithium tantalate, lithium niobate, and quartz; bauxite, magnesium oxide, sapphire, silicon nitride, aluminum nitride, silicon carbide, zirconium oxide, cordierite, mullite, block talc, and forsterite; various ceramics; dielectrics such as diamond and glass; and semiconductors such as gallium nitride.

[0152] The aforementioned electrodes 3 and 4, as well as the first and second busbars 5 and 6, comprise suitable metals or alloys such as Al or AlCu alloys. In this embodiment, electrodes 3 and 4, as well as the first and second busbars 5 and 6, have a structure in which an Al film is stacked on a Ti film. Alternatively, a close-fitting layer other than a Ti film may also be used.

[0153] During driving, an alternating voltage is applied between the plurality of electrodes 3 and the plurality of electrodes 4. More specifically, an alternating voltage is applied between the first busbar 5 and the second busbar 6. This allows for the resonant characteristics of a bulk wave utilizing the thickness shear mode excited in the piezoelectric layer 2. Furthermore, in the elastic wave device 1, when the thickness of the piezoelectric layer 2 is set to d and the center-to-center distance between any two adjacent electrodes 3 and 4 is set to p, d / p is set to 0.5 or less. Therefore, the aforementioned thickness shear mode bulk wave can be effectively excited, resulting in good resonant characteristics. More preferably, d / p is 0.24 or less, in which case even better resonant characteristics can be obtained.

[0154] In the elastic wave device 1, due to the aforementioned structure, even if the number of electrode pairs 3 and 4 is reduced to achieve miniaturization, a decrease in the Q value is not easily observed. This is because even if the number of electrode fingers in the reflectors on both sides is reduced, the propagation loss is still low. Furthermore, the reduction in the number of electrode fingers is possible due to the utilization of a volume wave with a thickness shear mode. (Refer to...) Figure 18 (a) and Figure 18 (b) explains the difference between the Lamb wave used in the elastic wave device and the volume wave of the thickness shear mode described above.

[0155] Figure 18(a) is a schematic front sectional view illustrating the Lamb wave propagating in the piezoelectric film of an elastic wave device as described in Japanese Patent Publication No. 2012-257019. Here, the wave propagates in the piezoelectric film 201 as indicated by the arrow. In the piezoelectric film 201, a first main surface 201a and a second main surface 201b face each other, and the thickness direction connecting the first main surface 201a and the second main surface 201b is the Z-direction. The X-direction is the direction in which the electrode fingers of the IDT electrodes are arranged. Figure 18 As shown in (a), if it is a Lamb wave, the wave propagates continuously in the X direction as illustrated. Since it is a plate wave, although the piezoelectric film 201 vibrates as a whole, the wave propagates in the X direction. Therefore, by placing reflectors on both sides, a resonant characteristic is obtained. As a result, wave propagation loss occurs, and the Q value decreases when miniaturization is sought, i.e., the number of electrode fingers is reduced.

[0156] In contrast, such as Figure 18 As shown in (b), in the elastic wave device 1, the vibration displacement is in the thickness shear direction. Therefore, the wave propagates and resonates approximately in the Z direction, which is the direction connecting the first principal surface 2a and the second principal surface 2b of the piezoelectric layer 2. That is, the X-direction component of the wave is significantly smaller than the Z-direction component. Moreover, since the resonant characteristics can be obtained through the propagation of the wave in this Z-direction, propagation loss is not easily generated even if the number of electrode fingers of the reflector is reduced. Furthermore, even if the number of electrode pairs including electrodes 3 and 4 is reduced in order to promote miniaturization, the decrease in Q value is not easily generated.

[0157] In addition, such as Figure 19 As shown, the amplitude direction of the bulk wave in the thickness shear mode becomes opposite in the first region 451 and the second region 452 contained in the excitation region C of the piezoelectric layer 2. Figure 19 The diagram schematically illustrates a bulk wave when a voltage higher than that of electrode 3 is applied between electrodes 3 and 4. The first region 451 is the region in excitation region C between the virtual plane VP1, which is orthogonal to the thickness direction of the piezoelectric layer 2 and divides the piezoelectric layer 2 into two parts, and the first main surface 2a. The second region 452 is the region in excitation region C between the virtual plane VP1 and the second main surface 2b.

[0158] As described above, the elastic wave device 1 is provided with at least one pair of electrodes, including electrodes 3 and 4. However, since the wave is not propagated in the X direction, the number of electrode pairs including electrodes 3 and 4 does not need to be multiple. That is, it is sufficient to provide at least one pair of electrodes.

[0159] For example, electrode 3 is connected to the signal potential, and electrode 4 is connected to the ground potential. However, it is also possible that electrode 3 is connected to the ground potential, and electrode 4 is connected to the signal potential. In this embodiment, as described above, at least one pair of electrodes is either connected to the signal potential or connected to the ground potential, and no floating electrode is provided.

[0160] Figure 20 It is shown Figure 17 The diagram shows the resonant characteristics of the elastic wave device. Furthermore, the design parameters for the elastic wave device 1 with these resonant characteristics are as follows.

[0161] Piezoelectric layer 2: LiNbO3 with Euler angles (0°, 0°, 90°) and a thickness of 400 nm.

[0162] When viewed in a direction orthogonal to the length direction of electrodes 3 and 4, the length of the overlapping region of electrodes 3 and 4, i.e., the excitation region C, is 40 μm. The number of electrode pairs containing electrodes 3 and 4 is 21 pairs. The center distance between electrodes is 3 μm. The width of electrodes 3 and 4 is 500 nm. d / p = 0.133.

[0163] Insulating layer 7: Silicon oxide film with a thickness of 1 μm.

[0164] Supporting component 8: Si.

[0165] In addition, the length of the so-called excitation region C is the dimension of the excitation region C along the length direction of electrodes 3 and 4.

[0166] In this embodiment, the distance between the electrodes in the electrode pairs including electrodes 3 and 4 is set to be equal in all pairs. That is, electrodes 3 and 4 are arranged at equal intervals.

[0167] according to Figure 20 It is clear that, despite the absence of a reflector, a good resonant characteristic with a relative bandwidth of 12.5% ​​was achieved.

[0168] Furthermore, when the thickness of the piezoelectric layer 2 is set to d and the center-to-center distance between the electrodes of electrode 3 and electrode 4 is set to p, as described above, in this embodiment, d / p is 0.5 or less, more preferably 0.24 or less. (Refer to...) Figure 21 This needs to be explained.

[0169] With obtained Figure 20 Similarly, by changing the d / p ratio, multiple elastic wave devices were obtained, just as shown in the example of the elastic wave device with resonant characteristics. Figure 21 This is a graph showing the relationship between the d / p ratio and the relative bandwidth of the elastic wave device as a resonator.

[0170] according to Figure 21It is clear that if d / p > 0.5, even with adjustments to d / p, the relative bandwidth will be less than 5%. In contrast, when d / p ≤ 0.5, by varying d / p within this range, the relative bandwidth can be set to 5% or more, thus enabling the construction of a resonator with a high coupling coefficient. Furthermore, when d / p is below 0.24, the relative bandwidth can be increased to 7% or more. Moreover, by adjusting d / p within this range, a resonator with an even wider relative bandwidth can be obtained, achieving a resonator with a higher coupling coefficient. Therefore, it can be seen that by setting d / p to 0.5 or less, a resonator with a high coupling coefficient utilizing the aforementioned thickness shear mode for bulk waves can be constructed.

[0171] Figure 22 This is a top view of an elastic wave device utilizing a thickness shear mode for bulk waves. In the elastic wave device 80, a pair of electrodes, having electrodes 3 and 4, are provided on the first main surface 2a of the piezoelectric layer 2. Furthermore, Figure 22 K in the figure represents the cross width. As mentioned earlier, in the elastic wave device of the present invention, the number of electrode pairs can also be 1 pair. Even in this case, as long as the above-mentioned d / p is 0.5 or less, it is possible to effectively excite the body wave of the thickness shear mode.

[0172] In the elastic wave device 1, it is preferable that, among the plurality of electrodes 3 and 4, the metallization ratio MR of the overlapping region (i.e., the excitation region C) when any adjacent electrodes 3 and 4 are viewed in opposite directions satisfies MR ≤ 1.75(d / p) + 0.075. In this case, stray emissions can be effectively reduced. (Refer to...) Figure 23 as well as Figure 24 This needs to be explained. Figure 23 This is a reference diagram illustrating an example of the resonant characteristics of the aforementioned elastic wave device 1. The spurious signal indicated by arrow B occurs between the resonant frequency and the anti-resonant frequency. Furthermore, d / p is set to 0.08, and the Euler angles of LiNbO3 are set to (0°, 0°, 90°). Additionally, the metallization ratio MR is set to 0.35.

[0173] Reference Figure 16 (b) Explains the metallization ratio MR. Figure 16In the electrode configuration of (b), considering only one pair of electrodes 3 and 4, it is assumed that only this one pair of electrodes 3 and 4 is provided. In this case, the portion enclosed by the single-dotted line is called the excitation region C. The excitation region C is the region in electrode 3 that overlaps with electrode 4 when viewed in the opposite direction, which is orthogonal to the length direction of electrodes 3 and 4, the region in electrode 4 that overlaps with electrode 3, and the region between electrodes 3 and 4 where electrodes 3 and 4 overlap. Furthermore, the area of ​​electrodes 3 and 4 within the excitation region C relative to the area of ​​the excitation region C is called the metallization ratio MR. That is, the metallization ratio MR is the ratio of the area of ​​the metallized portion to the area of ​​the excitation region C.

[0174] In addition, when multiple pairs of electrodes are provided, the ratio of the metallized portion contained in the entire excitation region to the total area of ​​the excitation region can be set as MR.

[0175] Figure 24 This is a graph showing the relationship between the relative bandwidth and the phase rotation of the stray impedance, which is normalized by 180 degrees, when multiple elastic wave resonators are constructed according to this embodiment. Furthermore, the relative bandwidth has been adjusted by various changes to the thickness of the piezoelectric layer and the dimensions of the electrodes. Additionally, Figure 24 This is the result when using a piezoelectric layer of LiNbO3 with Z-cut, but the same tendency also occurs when using piezoelectric layers with other cut angles.

[0176] exist Figure 24 In the region enclosed by ellipse J, the stray energy increases to 1.0. According to... Figure 24 It is clear that if the relative bandwidth exceeds 0.17, that is, if it exceeds 17%, then even if the parameters constituting the relative bandwidth are changed, large spurious emissions with a spurious level of 1 or higher will appear within the passband. That is, if... Figure 23 As shown in the resonance characteristics, a large spurious signal, indicated by arrow B, appears within the frequency band. Therefore, a relative bandwidth of 17% or less is preferred. In this case, the spurious signal can be reduced by adjusting the thickness of the piezoelectric layer 2, the dimensions of electrodes 3 and 4, etc.

[0177] Figure 25 This is a graph showing the relationship between d / 2p, metallization ratio (MR), and relative bandwidth. Various elastic wave devices with different d / 2p and MR were constructed in the above-mentioned elastic wave devices, and the relative bandwidth was measured. Figure 25The area shown by the shading to the right of the dashed line D is the region with a relative bandwidth of 17% or less. The boundary between the shading and unshading areas is represented by MR = 3.5(d / 2p) + 0.075, that is, MR = 1.75(d / p) + 0.075. Therefore, it is preferable that MR ≤ 1.75(d / p) + 0.075. In this case, it is easier to make the relative bandwidth less than 17%. More preferably... Figure 25 The region to the right of MR = 3.5(d / 2p) + 0.05 is shown by the single-dotted line D1. That is, as long as MR ≤ 1.75(d / p) + 0.05, the relative bandwidth can be reliably kept below 17%.

[0178] Figure 26 This is a diagram showing the mapping of the relative bandwidth to the Euler angles (0°, θ, ψ) of LiNbO3 when d / p is infinitely close to 0. Figure 26 The area shown by the shading is a region with a relative bandwidth of at least 5%. If the range of this region is approximated, it becomes the range represented by the following equations (1), (2) and (3).

[0179] (0°±10°, 0°~20°, any ψ)…Equation (1)

[0180] (0°±10°, 20°~80°, 0°~60°(1-(θ-50) 2 / 900) 1 / 2 () or (0°±10°, 20°~80°, [180°-60°(1-(θ-50))) 2 / 900) 1 / 2 [~180°)…Equation (2)

[0181] (0°±10°,[180°-30°(1-(ψ-90) 2 / 8100) 1 / 2 ]~180°, any ψ)…Equation (3)

[0182] Therefore, within the Euler angle range of equations (1), (2), or (3) above, it is preferable to have a sufficiently wide relative bandwidth. The same applies when the piezoelectric layer 2 is a lithium tantalate layer.

[0183] Figure 27 This is a partially cut-off three-dimensional diagram used to illustrate an elastic wave device utilizing Lamb waves.

[0184] The elastic wave device 81 has a support substrate 82. A recess with an open upper surface is provided on the support substrate 82. A piezoelectric layer 83 is stacked on the support substrate 82, thus forming a cavity 9. An IDT electrode 84 is provided on the piezoelectric layer 83 above the cavity 9. Reflectors 85 and 86 are provided on both sides of the IDT electrode 84 in the elastic wave propagation direction. Figure 27 In the diagram, the outer periphery of the cavity 9 is shown by a dashed line. Here, the IDT electrode 84 has first and second busbars 84a and 84b, and multiple first electrode fingers 84c and multiple second electrode fingers 84d. The multiple first electrode fingers 84c are connected to the first busbar 84a. The multiple second electrode fingers 84d are connected to the second busbar 84b. The multiple first electrode fingers 84c and the multiple second electrode fingers 84d are interleaved and interlocked.

[0185] In the elastic wave device 81, an alternating electric field is applied to the IDT electrode 84 on the aforementioned cavity 9, thereby exciting a Lamb wave as a plate wave. Furthermore, since reflectors 85 and 86 are provided on both sides, resonance characteristics based on the aforementioned Lamb wave can be obtained.

[0186] In this way, the elastic wave device of the present invention can also utilize plate waves. In this case, as long as the piezoelectric layer described in the first to fifth embodiments or their variations is provided... Figure 27 The IDT electrode 84, reflector 85, and reflector 86 shown are sufficient.

[0187] In the elastic wave devices of the first to fifth embodiments or their variations having an elastic wave resonator utilizing a thickness shear mode for bulk waves, as described above, d / p is preferably 0.5 or less, more preferably 0.24 or less. This results in better resonance characteristics. Furthermore, in the elastic wave devices of the first to fifth embodiments or their variations having an elastic wave resonator utilizing a thickness shear mode for bulk waves, as described above, it is preferable that MR ≤ 1.75(d / p) + 0.075. In this case, spurious emissions can be suppressed more reliably.

[0188] In the elastic wave devices of embodiments 1 to 5, or their variations, which have an elastic wave resonator utilizing a thickness shear mode for bulk waves, the piezoelectric layer is preferably a lithium niobate layer or a lithium tantalate layer. Furthermore, the Euler angles of the lithium niobate or lithium tantalate constituting this piezoelectric layer are... Preferably, it falls within the range of equation (1), equation (2), or equation (3) above. In this case, the relative bandwidth can be made sufficiently wide.

[0189] Explanation of reference numerals in the attached figures

[0190] 1: Elastic wave device;

[0191] 2: Piezoelectric layer;

[0192] 2a, 2b: First and second main faces;

[0193] 3, 4: Electrodes;

[0194] 5, 6: Busbars 1 and 2;

[0195] 7: Insulation layer;

[0196] 7a: Through hole;

[0197] 8: Supporting components;

[0198] 8a: Through hole;

[0199] 9: Hollow section;

[0200] 10: Elastic wave device;

[0201] 10a, 10b: The first and second cavities;

[0202] 11: IDT electrode;

[0203] 12: Piezoelectric substrate;

[0204] 13: Supporting components;

[0205] 14: Piezoelectric layer;

[0206] 14a, 14b: 1st and 2nd main surfaces;

[0207] 15: Intermediate layer;

[0208] 16: Support base plate;

[0209] 17A: Electrode layer;

[0210] 17B, ​​17C: Conductive films;

[0211] 18, 18A: First support body;

[0212] 18a, 18b: Parts 1 and 2;

[0213] 18c: Opening;

[0214] 18d, 18e: Layer 1 and Layer 2;

[0215] 19: Second support body;

[0216] 19a, 19b: Parts 1 and 2;

[0217] 19d, 19e: Layer 1 and Layer 2;

[0218] 20: Through hole;

[0219] 21A: Via electrode;

[0220] 21B: Electrode pad;

[0221] 22: Bump;

[0222] 23: Wiring electrode;

[0223] 24: Dielectric film;

[0224] 25: cover;

[0225] 26, 26A: Main body of the cover;

[0226] 26a, 26b: First and second main faces;

[0227] 27A, 27B: Insulating layers;

[0228] 30c: Third cavity section;

[0229] 39, 39A: Second support body;

[0230] 48: First support body;

[0231] 48a, 48b: Parts 1 and 2;

[0232] 48d~48f, 48g~48i: Layers 1 to 3;

[0233] 48j: Level 1;

[0234] 48x: Part 2;

[0235] 50a: The first cavity;

[0236] 53: Supporting components;

[0237] 58: Third support body;

[0238] 58a, 58b: Parts 1 and 2;

[0239] 58d~58f, 58g~58i: Layers 1 to 3;

[0240] 69: Second support body;

[0241] 70: Elastic wave device;

[0242] 71A: Upper electrode;

[0243] 71B: Lower electrode;

[0244] 80, 81: Elastic wave device;

[0245] 82: Support base plate;

[0246] 83: Piezoelectric layer;

[0247] 84: IDT electrode;

[0248] 84a, 84b: Busbar 1 and Busbar 2;

[0249] 84c, 84d: These refer to the first and second electrodes;

[0250] 85, 86: Reflectors;

[0251] 201: Piezoelectric film;

[0252] 201a, 201b: First and second main faces;

[0253] 451, 452: Regions 1 and 2;

[0254] C: Incentive region;

[0255] VP1: Virtual plane.

Claims

1. An elastic wave device, comprising: A piezoelectric substrate, comprising a support member including a support substrate and a piezoelectric layer disposed on the support member; Functional electrodes are disposed on the piezoelectric layer; At least one support; and cover, One of the at least one support body is configured on the piezoelectric substrate to surround the functional electrode, and a cover portion is provided on the support body. The support member has a first cavity, which overlaps with at least a portion of the functional electrode when viewed from above. A second cavity is provided, which is surrounded by the piezoelectric substrate, the support body disposed between the piezoelectric substrate and the cover, and the cover. When the direction in which the piezoelectric substrate, the support body disposed between the piezoelectric substrate and the cover portion are stacked is defined as the height direction, and the dimension along the height direction is defined as the height, the height of the first cavity portion is higher than the height of the second cavity portion.

2. The elastic wave device according to claim 1, wherein, It also includes wiring electrodes disposed on the piezoelectric layer. At least a portion of the wiring electrode overlaps with the first cavity when viewed from above.

3. The elastic wave device according to claim 2, wherein, The wiring electrodes are provided throughout the piezoelectric layer, including portions that overlap with the first cavity when viewed from above and portions that do not overlap with the first cavity when viewed from above.

4. The elastic wave device according to any one of claims 1 to 3, wherein, The piezoelectric layer has a first principal surface and a second principal surface that are opposite to each other. The elastic wave device further includes a dielectric film, at least a portion of which is disposed on at least one of the first main surface and the second main surface, in a portion that overlaps with the first void portion when viewed from above.

5. The elastic wave device according to claim 4, wherein, The first main surface and the second main surface of the piezoelectric layer are located on the side of the support member, and the dielectric film is disposed on the second main surface.

6. The elastic wave device according to any one of claims 1 to 3, wherein, The support and the cover, which are disposed between the piezoelectric substrate and the cover side, are configured as separate parts.

7. The elastic wave device according to any one of claims 1 to 3, wherein, The cover includes a cover body mainly composed of semiconductors.

8. The elastic wave device according to any one of claims 1 to 3, wherein, The support body disposed between the piezoelectric substrate and the cover portion, and the cover portion, contain resin, and the support body and the cover portion are integrally formed.

9. The elastic wave device according to any one of claims 1 to 3, wherein, The support has a first portion and a second portion disposed on the side of the piezoelectric layer in the height direction compared to the first portion.

10. The elastic wave device according to claim 9, wherein, The first part and the second part contain different kinds of metals.

11. The elastic wave device according to claim 9, wherein, In the support body, the portion of the first part closest to the second part and the portion of the second part closest to the first part contain the same material. This constitutes an integral part in which the portion of the first part closest to the second part and the portion of the second part closest to the first part are integrated. Viewed from above, the area of ​​the portion of the first part closest to the second part is different from the area of ​​the portion of the second part closest to the first part.

12. The elastic wave device according to claim 11, wherein, At least one of the first part and the second part is a laminate. Viewed from above, the area of ​​at least one layer other than the layer constituting the integral part in the laminate is larger than the area of ​​the layer constituting the integral part in the laminate.

13. The elastic wave device according to claim 12, wherein, In the laminate, the area of ​​all layers other than the layer constituting the integral part is larger than the area of ​​the integral part.

14. The elastic wave device according to claim 13, wherein, In the stacked body, the further away a layer is from the layer that constitutes the integral part, the larger its area when viewed from above.

15. The elastic wave device according to any one of claims 12 to 14, wherein, The number of layers in the laminate of the support is at least 3.

16. The elastic wave device according to any one of claims 12 to 14, wherein, The smaller of the portions constituting the integral part in the first and second parts, when viewed from above, is the laminate.

17. The elastic wave device according to any one of claims 12 to 14, wherein, Both the first part and the second part are the laminated body.

18. The elastic wave device according to any one of claims 11 to 14, wherein, The integral part contains Au.

19. The elastic wave device according to claim 9, wherein, The support body disposed between the piezoelectric substrate and the cover side is the first support body. The elastic wave device further includes at least one second support body disposed on the piezoelectric substrate and disposed within the second cavity. The first support and the second support each have a first portion disposed on the cover side and a second portion disposed on the piezoelectric substrate side, respectively. A first integral part comprising the portion of the first part closest to the second part and the portion of the second part closest to the first part, forming an integral unit. A second integral part, comprising the portion of the first part closest to the second part and the portion of the second part closest to the first part, is integrally formed. When the dimensions of each portion of the first support body are defined as the width of each portion of the first support body in a direction orthogonal to both the direction in which the piezoelectric substrate, the first support body, and the cover are stacked and the direction in which the first support body extends on the piezoelectric substrate, the dimensions of each portion of the second support body in a direction orthogonal to the direction in which the piezoelectric substrate, the second support body, and the cover are stacked, the width of at least a portion of the second integral portion in at least one of the second support bodies is narrower than the width of the first integral portion.

20. The elastic wave device according to claim 19, wherein, The second support is electrically connected to the functional electrode.

21. The elastic wave device according to claim 19 or 20, wherein, The width of the second integral part is more than 1 μm and less than 16 μm.

22. The elastic wave device according to any one of claims 1 to 3, wherein, The area of ​​the second cavity viewed from above is larger than the area of ​​the first cavity viewed from above.

23. The elastic wave device according to claim 22, wherein, The support body disposed between the piezoelectric substrate and the cover side is the first support body. The elastic wave device further includes at least one second support body disposed on the piezoelectric substrate and disposed within the second cavity. Viewed from above, the second support does not overlap with the first cavity. The area of ​​the second cavity, viewed from above, is obtained by subtracting the area of ​​the second support from the area of ​​the portion surrounded by the first support.

24. The elastic wave device according to any one of claims 1 to 3, wherein, The support body disposed between the piezoelectric substrate and the cover side is the first support body. The elastic wave device further includes at least one second support body disposed on the piezoelectric substrate and disposed within the second cavity. At least one of the second supports is disposed between the first support and the functional electrode.

25. The elastic wave device according to any one of claims 1 to 3, wherein, The support body disposed between the piezoelectric substrate and the cover side is the first support body. The elastic wave device further includes a plurality of second supports disposed on the piezoelectric substrate and arranged within the second cavity. The plurality of second supports include at least one pair of second supports configured to clamp the functional electrode.

26. The elastic wave device according to any one of claims 1 to 3, wherein, The support body disposed between the piezoelectric substrate and the cover side is the first support body. The elastic wave device further includes at least one second support body disposed on the piezoelectric substrate and disposed within the second cavity. The second support has a first portion disposed on the cover side and a second portion disposed on the piezoelectric substrate side, the first portion and the second portion comprising different types of metals.

27. The elastic wave device according to any one of claims 1 to 3, wherein, The support body disposed between the piezoelectric substrate and the cover side is the first support body. The elastic wave device further includes at least one second support body disposed on the piezoelectric substrate and disposed within the second cavity. The second support has one of the following shapes: a wall-like shape and a column-like shape.

28. The elastic wave device according to claim 27, wherein, It also includes wiring electrodes disposed on the piezoelectric substrate. The support member is provided with a third cavity that is not connected to the first cavity. The third cavity overlaps with the wiring electrode when viewed from above, but does not overlap with the second support or the functional electrode.

29. The elastic wave device according to any one of claims 1 to 3, wherein, The at least one support is simply the support disposed between the piezoelectric substrate and the cover side.

30. The elastic wave device according to any one of claims 1 to 3, wherein, The at least one support further includes a support disposed between the support substrate and the piezoelectric layer.

31. The elastic wave device according to any one of claims 1 to 3, wherein, The support member includes an intermediate layer disposed between the support substrate and the piezoelectric layer.

32. The elastic wave device according to any one of claims 1 to 3, wherein, The support member includes an intermediate layer disposed between the support substrate and the piezoelectric layer. At least a portion of the first cavity is disposed in the intermediate layer.

33. The elastic wave device according to any one of claims 1 to 3, wherein, The piezoelectric layer is a lithium tantalate layer or a lithium niobate layer.

34. The elastic wave device according to any one of claims 1 to 3, wherein, The functional electrode has a first busbar and a second busbar facing each other, a first electrode finger connected to the first busbar, and a second electrode finger connected to the second busbar.

35. The elastic wave device according to claim 34, wherein, The functional electrode is an IDT electrode having multiple first electrode fingers and multiple second electrode fingers respectively.

36. The elastic wave device according to claim 35, wherein, The elastic wave device is configured to utilize plate waves.

37. The elastic wave device according to claim 34, wherein, The elastic wave device is configured to utilize a body wave with a thickness shear mode.

38. The elastic wave device according to claim 34, wherein, When the thickness of the piezoelectric layer is set to d and the center-to-center distance between adjacent first electrode fingers and second electrode fingers is set to p, d / p is 0.5 or less.

39. The elastic wave device according to claim 38, wherein, d / p is below 0.

24.

40. The elastic wave device according to claim 38 or 39, wherein, When viewed from a direction where adjacent first electrode fingers and second electrode fingers are opposite each other, the area where adjacent first electrode fingers and second electrode fingers overlap is the excitation region. When the metallization ratio of the first electrode fingers and the second electrode fingers relative to the excitation region is set as MR, MR ≤ 1.75 (d / p) + 0.075 is satisfied.

41. The elastic wave device according to any one of claims 37 to 39, wherein, The piezoelectric layer is a lithium tantalate layer or a lithium niobate layer. The Euler angles (φ, θ, ψ) of the lithium niobate or lithium tantalate constituting the piezoelectric layer are within the range of the following equations (1), (2), or (3). (0°±10°, 0°~20°, any ψ) … Equation (1) (0°±10°, 20°~80°, 0°~60° (1-(θ-50) 2 / 900) 1 / 2 ) or (0°±10°, 20°~80°, [180°-60° (1-(θ-50))) 2 / 900) 1 / 2 [180°] …Equation (2) (0°±10°, [180°-30° (1-(ψ-90) 2 / 8100) 1 / 2 [180°, any ψ] … Equation (3).

42. The elastic wave device according to any one of claims 1 to 3, wherein, The piezoelectric layer has a first principal surface and a second principal surface that are opposite to each other. The functional electrode has an upper electrode disposed on the first main surface of the piezoelectric layer and a lower electrode disposed on the second main surface, the upper electrode and the lower electrode sandwiching the piezoelectric layer and facing each other.

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