Elastic wave device

Abstract

To provide an elastic wave device that has improved heat dissipation.SOLUTION: An elastic wave filter 1 includes: a substrate 10 having principal surfaces 10a and 10b facing each other; a substrate 70 having a principal surface 70a facing the principal surface 10a; functional electrodes 31 and 32 disposed in the principal surface 70a; and a frame member 20 disposed between the principal surfaces 10a and 70a, the frame member 20 including: a wall body 22 surrounding the functional electrodes 31 and 32 in plan view of the principal surfaces 10a and 70a; and a wall body 21 disposed in the outer periphery of the wall body 22 via a gap 81 in the plan view, the wall body 21 having at least one opening 80 penetrating between an inner peripheral surface 21a and an outer peripheral surface 21b and communicating with the gap 81.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an acoustic wave device. [Background technology]

[0002] Patent Document 1 discloses a microelectromechanical device (acoustic wave device) that includes a thin-film piezoelectric element disposed between an upper substrate and a lower substrate, and a sealing ring having a multi-ring structure that is disposed so as to surround the thin-film piezoelectric element. The document claims that this configuration enables reliable sealing (airtightness). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-288497 Summary of the Invention [Problem to be solved by the invention]

[0004] With the demand for higher output power in mobile communications, there is a demand for acoustic wave devices with improved airtightness and heat dissipation properties.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an acoustic wave device with improved heat dissipation properties. [Means for solving the problem]

[0006] In order to achieve the above object, an elastic wave device according to one embodiment of the present invention comprises a first substrate having first and second main surfaces facing each other, a second substrate having a third main surface facing the first main surface, a functional electrode arranged on the third main surface, and a frame body arranged between the first and third main surfaces, wherein the frame body includes a first wall body that surrounds the functional electrode when the first and third main surfaces are viewed in a plane, and a second wall body that, in the above-mentioned plane view, is arranged on the outer periphery of the first wall body with a gap interposed therebetween, and the second wall body has at least one opening that penetrates between the inner surface and the outer surface and communicates with the gap.

[0007] Furthermore, an elastic wave device according to one embodiment of the present invention includes a first substrate having a first main surface and a second main surface facing each other, a second substrate having a third main surface facing the first main surface, a functional electrode arranged on the third main surface, and a frame body arranged between the first and third main surfaces, wherein the frame body includes a first wall body that surrounds the functional electrode when the first and third main surfaces are viewed in a plane, and a second wall body that, in the planar view, is arranged along a portion of the first wall body on the outer periphery of the first wall body with a gap interposed therebetween, and in the planar view, the gap communicates with the outer periphery region of the second wall body via both ends of the second wall body. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide an acoustic wave device with improved heat dissipation properties. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of an acoustic wave filter according to an embodiment of the present invention; [Figure 2] FIG. 1 is a plan view of an acoustic wave filter according to an embodiment. [Figure 3A] 1A and 1B are a plan view and a cross-sectional view schematically illustrating a first example of an acoustic wave resonator included in an acoustic wave filter according to an embodiment. [Figure 3B] FIG. 4 is a cross-sectional view schematically illustrating a second example of an acoustic wave resonator included in an acoustic wave filter according to an embodiment. [Figure 3C] FIG. 10 is a cross-sectional view schematically illustrating a third example of an acoustic wave resonator included in an acoustic wave filter according to an embodiment. [Figure 4] FIG. 10 is a plan view of an acoustic wave filter according to a first modification of an embodiment of the present invention. [Figure 5] FIG. 10 is a plan view of an acoustic wave filter according to a second modification of the embodiment. [Figure 6] FIG. 11 is a cross-sectional view of an acoustic wave filter according to a third modification of the embodiment. [Figure 7] FIG. 11 is a plan view of an acoustic wave filter according to a third modification of the embodiment. [Figure 8A]10A and 10B are diagrams illustrating electron microscope images of the outer cross section and outer surface of a first wall according to a third modification of the embodiment. [Figure 8B] 10A and 10B are diagrams illustrating electron microscope images of the inner cross section and inner surface of the first wall according to the third modification of the embodiment. [Figure 9] 10 is a diagram showing a method for evaluating the surface area of ​​a first wall body according to a third modification of the embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component arrangements, and connection forms shown in the following embodiments are merely examples and are not intended to limit the present invention. Among the components in the following embodiments, components that are not recited in independent claims will be described as optional components. Furthermore, the sizes or size ratios of the components shown in the drawings are not necessarily strict.

[0011] It should be noted that the drawings are schematic diagrams in which emphasis, omission, or adjustment of proportions has been appropriately made to illustrate the present invention, and are not necessarily strictly illustrated, and may differ from the actual shapes, positional relationships, and proportions. In the drawings, the same reference numerals are used to denote substantially the same components, and redundant explanations may be omitted or simplified.

[0012] In the circuit configuration of the present disclosure, "connected" includes not only direct connection by electrodes and / or wiring conductors, but also electrical connection via matching elements such as inductors and capacitors, and switch circuits. "Connected between A and B" means connected to both A and B between A and B.

[0013] Furthermore, terms indicating the relationship between elements, such as "parallel" and "perpendicular," terms indicating the shape of elements, such as "rectangle," and numerical ranges do not only represent strict meanings, but also include substantially equivalent ranges, for example, including an error of a few percent.

[0014] (Embodiment) [1 Structure of acoustic wave filter 1] Fig. 1 is a cross-sectional view of an acoustic wave filter 1 according to an embodiment. Fig. 2 is a plan view of the acoustic wave filter 1 according to an embodiment. Fig. 2 is a plan view (transparent view) of a cross section taken along line II-II in Fig. 1, viewed from the positive side of the z-axis. Fig. 1 is a view of the cross-section taken along line II in Fig. 2, viewed from the negative side of the y-axis.

[0015] The acoustic wave filter 1 is an example of an acoustic wave device, and as shown in Figures 1 and 2, it includes substrates 10 and 70, a frame 20, functional electrodes 31 and 32, signal conductors 35 and 36, a via conductor 11, connection wiring 33, 34, 37 and 38, an insulating film 13, a planar electrode 12, and a bump electrode 40.

[0016] The substrate 10 is an example of a first substrate and has opposing principal surfaces 10a (first principal surface) and 10b (second principal surface). In this embodiment, the substrate 10 contains silicon. When the substrate 10 contains silicon, the thermal conductivity is increased compared to when the substrate 10 is made of a resin material. This improves the heat dissipation of the acoustic wave filter 1. Furthermore, the processing accuracy of the substrate 10 is improved.

[0017] The substrate 70 is an example of a second substrate, and has principal surfaces 70a (third principal surface) and 70b facing each other. The principal surfaces 10a and 70a face each other. In this embodiment, the substrate 70 has piezoelectricity.

[0018] The functional electrodes 31 and 32 are arranged on the main surface 70a, and in this embodiment, are part of an IDT (InterDigital Transducer) electrode that performs electromechanical transduction with the substrate 70. Examples of the structures of the functional electrodes 31 and 32 will be described with reference to FIGS. 3A to 3C.

[0019] The frame 20 is disposed between the main surfaces 10 a and 70 a and includes walls 21 , 22 , 23 , 24 and 25 .

[0020] The wall 22 is an example of a first wall, and as shown in FIG. 2, is disposed between the principal surfaces 10a and 70a so as to surround the functional electrodes 31 and 32 when the principal surfaces 10a and 70a are viewed in plan.

[0021] The wall 21 is an example of a second wall, and as shown in FIG. 2, is arranged to surround the wall 22 via a gap 81 in the plan view. Also, as shown in FIG. 2, the wall 21 has an opening 80 that penetrates between the inner peripheral surface 21a and the outer peripheral surface 21b and communicates with the gap 81. It is sufficient to have at least one opening 80. In this embodiment, the wall 21 is composed of four wall portions arranged along each outer edge of the substrate 70 that has a rectangular shape in the plan view, and an opening 80 is arranged in each of the four wall portions. In other words, the wall 21 has multiple openings 80 that communicate with the gap 81. The wall 21 does not have to completely surround the wall 22. For example, the wall 21 may have three wall portions arranged along three of the four outer edges of the rectangular substrate 70, and no wall portion is arranged along the remaining outer edge. That is, the wall 21 may be disposed on the outer periphery of the wall 22 with the gap 81 interposed therebetween in the plan view.

[0022] Walls 23 and 25 are an example of a third wall, and as shown in Fig. 1, are arranged between main surface 10a and walls 21 and 22 and are joined to main surface 10a and walls 21 and 22. Wall 24 is arranged between main surface 70a and walls 21 and 22 and is joined to main surface 70a and walls 21 and 22. At least one of walls 23, 24, and 25 does not have to be included in frame 20.

[0023] Walls 21 and 22 include a conductor portion mainly composed of, for example, aluminum (Al). Each of walls 21 and 22 may include a conductor portion made of metal. Each of walls 23, 24, and 25 includes a conductor portion mainly composed of, for example, at least one of aluminum (Al), copper (Cu), gold (Au), platinum (Pt), and titanium (Ti).

[0024] The wall 22 separates the internal space, in which the functional electrodes 31 and 32 are formed, from the external space. The internal space refers to the space inside the wall 22, and the external space refers to the space outside the wall 22. Furthermore, since the walls 22 to 25 include a conductor portion made of metal, it is possible to ensure the airtightness of the internal space with high precision.

[0025] According to the above configuration, an air flow (air current) is generated in the gap 81 and the opening 80 due to a temperature difference between the wall 22, which is in contact with the internal space in which the functional electrodes 31 and 32, which are heat-generating bodies, are disposed, and the wall 21, which is in contact with the external space. That is, the heat of the wall 22 can be efficiently dissipated to the external space of the wall 21 via the air current in the gap 81 and the opening 80. Therefore, an acoustic wave filter 1 with improved heat dissipation properties can be provided.

[0026] Furthermore, by providing a plurality of openings 80 communicating with the void 81, the air flow rate and flow velocity in the void 81 can be increased, thereby more efficiently dissipating heat from the wall 22 to the space outside the wall 21. Furthermore, since the frame 20 has a double structure including the walls 21 and 22, the mechanical strength of the frame 20 as a support is increased, which enables the mechanical strength of the acoustic wave filter 1 to be increased.

[0027] It should be noted that frame 20 only needs to include walls 21 and 22, and does not necessarily need to include at least one of walls 23 to 25. Frame 20 may also be set to ground potential, which can block external noise.

[0028] Furthermore, a resin member may be disposed on the outer periphery of frame 20 so as to be in contact with the outer peripheral surface of wall 21. This can increase the moisture resistance of wall 21 and reinforce the mechanical strength of wall 21. It is desirable that the resin member has an opening that communicates with opening 80.

[0029] The signal conductor 35 is an example of a first conductor, and is arranged inside the frame body 20 in the plan view, connected to the functional electrode 31 via the connection wiring 33 formed on the main surface 70a, and connected to the via conductor 11 via the connection wiring 37 formed on the main surface 10a, to transmit a signal passing through the functional electrode 31. The signal conductor 36 is an example of a first conductor, and is arranged inside the frame body 20 in the plan view, connected to the functional electrode 32 via the connection wiring 34 formed on the main surface 70a, and connected to the via conductor 11 via the connection wiring 38 formed on the main surface 10a, to transmit a signal passing through the functional electrode 32.

[0030] The signal conductors 35 and 36 have, for example, the same material configuration as the walls 21 and 22. The signal conductors 35 and 36 and the walls 21 and 22 may be formed in the same film formation process.

[0031] The connection wires 33 and 34 may be formed of the same material and by the same film-forming process as the functional electrodes 31 and 32. The connection wires 37 and 38 may be formed of the same material and by the same film-forming process as the wall body 25.

[0032] The via conductor 11 is an electrode disposed on the substrate 10 from the principal surface 10a toward the principal surface 10b and connected to the signal conductor 35 or 36. In this embodiment, the via conductor 11 is a through electrode filled in a cavity that penetrates the substrate 10 between the principal surface 10a and the principal surface 10b. The via conductor 11 is made of, for example, a metal member whose main component is Cu (copper).

[0033] The signal conductors 35 and 36 and the via conductor 11 allow signals passing through the functional electrodes 31 and 32 to be transmitted to the main surface 10b side.

[0034] In addition, via conductor 11 does not have to be a single via conductor extending from main surface 10a to main surface 10b, but may have a configuration in which multiple via conductors are connected via a planar electrode formed within substrate 10.

[0035] The insulating film 13 is disposed on the main surface 10b and is, for example, a silicon oxide film. The insulating film 13 may be omitted. Alternatively, an insulating film may be disposed on the main surface 70a.

[0036] The planar electrode 12 is disposed on the principal surface 10b and is bonded to the via conductors 11. The bump electrode 40 is bonded to the planar electrode 12 and is made of, for example, solder or a metal material mainly composed of Au (gold). The bump electrode 40 is bonded to, for example, an electrode on a mounting substrate on which the acoustic wave filter 1 is mounted.

[0037] According to the above configuration, a compact acoustic wave filter 1 can be provided in which functional electrodes 31 and 32 are arranged in a space surrounded by substrates 10, 70 and frame 20.

[0038] The acoustic wave filter 1 according to this preferred embodiment may not include at least one of the signal conductors 35 and 36, the connection lines 33, 34, 37 and 38, the via conductor 11, the insulating film 13, the planar electrode 12, and the bump electrode 40.

[0039] [2 Structure of functional electrodes 31 and 32] Next, exemplary structures of the functional electrodes 31 and 32 will be described. FIG. 3A is a plan view and a cross-sectional view schematically illustrating a first example of an acoustic wave resonator 60 constituting the acoustic wave filter 1 according to an embodiment. The drawings illustrate the basic structure of the acoustic wave resonator 60 constituting the acoustic wave filter 1. Note that the acoustic wave resonator 60 shown in FIG. 3A is intended to illustrate a typical structure of an acoustic wave resonator constituting the acoustic wave filter 1, and the number and length of electrode fingers constituting the electrodes are not limited to this.

[0040] The acoustic wave resonator 60 is composed of a piezoelectric substrate 50 and comb-shaped electrodes 60a and 60b.

[0041] As shown in (a) of FIG. 3A, a pair of comb-shaped electrodes 60a and 60b facing each other is formed on the piezoelectric substrate 50. The comb-shaped electrode 60a is composed of a plurality of parallel electrode fingers 61a (first electrode fingers) and a busbar electrode 62a (first busbar electrode) connecting one ends of the plurality of electrode fingers 61a together. The comb-shaped electrode 60b is composed of a plurality of parallel electrode fingers 61b (second electrode fingers) and a busbar electrode 62b (second busbar electrode) connecting one ends of the plurality of electrode fingers 61b together. The plurality of electrode fingers 61a and 61b are formed in a direction perpendicular to the acoustic wave propagation direction (X-axis direction). The busbar electrode 62a and the busbar electrode 62b are arranged facing each other with the electrode fingers 61a and 61b interposed therebetween. The comb-shaped electrodes 60a and 60b form an IDT electrode 54.

[0042] When the acoustic wave filter 1 according to this preferred embodiment performs electromechanical transduction using the IDT electrode 54, the substrate 70 shown in FIGS. 1 and 2 corresponds to the piezoelectric substrate 50. Each of the functional electrodes 31 and 32 shown in FIGS. 1 and 2 includes a plurality of electrode fingers 61a and a plurality of electrode fingers 61b. The busbar electrode shown in FIG. 2 is either the busbar electrode 62a or the busbar electrode 62b.

[0043] The acoustic wave resonator 60 may have reflectors on both ends of the IDT electrode 54 in the acoustic wave propagation direction (X-axis direction).

[0044] As shown in FIG. 3A(b), the IDT electrode 54 has a laminated structure of an adhesive layer 540 and a main electrode layer 542, for example.

[0045] The adhesion layer 540 is a layer for improving adhesion between the piezoelectric substrate 50 and the main electrode layer 542, and is made of, for example, Ti. The main electrode layer 542 is made of, for example, Al containing 1% Cu. The protective layer 55 is formed to cover the comb-shaped electrodes 60a and 60b. The protective layer 55 is a layer intended to protect the main electrode layer 542 from the external environment, adjust the frequency-temperature characteristics, and increase moisture resistance, and is, for example, a dielectric film whose main component is silicon dioxide.

[0046] The materials constituting the adhesion layer 540, the main electrode layer 542, and the protective layer 55 are not limited to those described above. Furthermore, the IDT electrode 54 does not have to have the laminated structure described above. The IDT electrode 54 may be made of a metal or alloy such as Ti, Al, Cu, Pt, Au, Ag, or Pd, or may be made of a laminate of multiple layers made of the above metals or alloys. Furthermore, the protective layer 55 does not necessarily have to be formed.

[0047] Next, the layered structure of the piezoelectric substrate 50 will be described.

[0048] As shown in (c) of Figure 3A, the piezoelectric substrate 50 includes a high acoustic speed support substrate 51, a low acoustic speed film 52, and a piezoelectric film 53, and has a structure in which the high acoustic speed support substrate 51, the low acoustic speed film 52, and the piezoelectric film 53 are stacked in this order.

[0049] The piezoelectric film 53 is made of, for example, a θ°Y-cut X-propagation LiTaO3 piezoelectric single crystal or piezoelectric ceramics (a lithium tantalate single crystal or ceramics cut along a plane whose normal is an axis rotated θ° from the Y axis around the X axis, and through which elastic waves propagate in the X-axis direction). The material and cut angle θ of the piezoelectric single crystal used as the piezoelectric film 53 are appropriately selected depending on the required specifications of each filter.

[0050] The high acoustic velocity support substrate 51 is a substrate that supports the low acoustic velocity film 52, the piezoelectric film 53, and the IDT electrode 54. The high acoustic velocity support substrate 51 is also a substrate in which the acoustic velocity of bulk waves in the high acoustic velocity support substrate 51 is faster than that of acoustic waves such as surface waves and boundary waves that propagate through the piezoelectric film 53, and functions to confine acoustic waves to the portion where the piezoelectric film 53 and the low acoustic velocity film 52 are laminated, preventing leakage below the high acoustic velocity support substrate 51. Examples of materials that can be used for the high acoustic velocity support substrate 51 include piezoelectric materials such as aluminum nitride, lithium tantalate, lithium niobate, and quartz; ceramics such as alumina, sapphire, magnesia, silicon nitride, silicon carbide, zirconia, cordierite, mullite, steatite, forsterite, spinel, and sialon; dielectrics such as aluminum oxide, silicon oxynitride, diamond-like carbon (DLC), and diamond; semiconductors such as silicon; and materials containing any of the above materials as a main component. The spinel includes an aluminum compound containing oxygen and one or more elements selected from Mg, Fe, Zn, Mn, etc. Examples of the spinel include MgAl2O4, FeAl2O4, ZnAl2O4, and MnAl2O4.

[0051] The low acoustic velocity film 52 is a film in which the acoustic velocity of the bulk waves in the low acoustic velocity film 52 is slower than that of the bulk waves propagating through the piezoelectric film 53, and is disposed between the piezoelectric film 53 and the high acoustic velocity support substrate 51. This structure and the property of the acoustic waves that energy is concentrated in a medium with an essentially low acoustic velocity suppress leakage of acoustic wave energy outside the IDT electrode 54. The low acoustic velocity film 52 can be made of a dielectric material such as glass, silicon oxide, silicon oxynitride, lithium oxide, tantalum oxide, or a compound in which fluorine, carbon, or boron is added to silicon oxide, or a material containing any of the above materials as a main component.

[0052] The above-described laminated structure of piezoelectric substrate 50 makes it possible to significantly increase the Q value at the resonant frequency and anti-resonant frequency compared to a conventional structure using a single-layer piezoelectric substrate. In other words, an acoustic wave resonator with a high Q value can be configured, and a filter with low insertion loss can be configured using the acoustic wave resonator.

[0053] The high acoustic velocity support substrate 51 may have a laminated structure of a support substrate and a high acoustic velocity film in which the acoustic velocity of the propagating bulk waves is faster than that of the surface waves and boundary waves, etc., that propagate through the piezoelectric film 53. In this case, the high acoustic velocity film may be made of the same material as the high acoustic velocity support substrate 51. The support substrate may be made of, for example, piezoelectric materials such as aluminum nitride, lithium tantalate, lithium niobate, and quartz; ceramics such as alumina, sapphire, magnesia, silicon nitride, silicon carbide, zirconia, cordierite, mullite, steatite, and forsterite; dielectric materials such as diamond and glass; semiconductors such as silicon and gallium nitride; resins; or materials containing any of the above materials as a main component.

[0054] The piezoelectric substrate 50 does not necessarily have to include the low acoustic velocity film 52. The piezoelectric substrate 50 may have a hollow space formed between the piezoelectric film 53 and the low acoustic velocity film 52 in a region facing the IDT electrode 54. The acoustic wave resonator 60 may have a configuration in which the IDT electrode 54 is disposed on only one of the two opposing principal surfaces of the piezoelectric film 53, or may have a configuration in which the IDT electrode 54 is disposed on both of the two opposing principal surfaces of the piezoelectric film 53.

[0055] In this specification, the term "major component of a material" refers to a component that accounts for more than 50% by weight of the material. The major component may be in a single crystal, polycrystalline, or amorphous state, or a mixture of these.

[0056] 3B is a cross-sectional view schematically illustrating a second example of an acoustic wave resonator 60 constituting the acoustic wave filter 1 according to the embodiment. In the acoustic wave resonator 60 illustrated in FIG. 3A, the IDT electrode 54 is formed on the piezoelectric substrate 50 having the piezoelectric film 53. However, the substrate on which the IDT electrode 54 is formed may be a piezoelectric single crystal substrate 57 consisting of a single piezoelectric layer, as illustrated in FIG. 1 and FIG. 2. In this case, the substrate 70 illustrated in FIGS. 1 and 2 corresponds to the piezoelectric single crystal substrate 57.

[0057] The piezoelectric single crystal substrate 57 is made of, for example, a piezoelectric single crystal of LiNbO3. The elastic wave resonator according to this example is made up of the LiNbO3 piezoelectric single crystal substrate 57, an IDT electrode 54, and a protective layer 58 formed on the piezoelectric single crystal substrate 57 and the IDT electrode 54.

[0058] The laminate structure, material, cut angle, and thickness of the piezoelectric film 53 and the piezoelectric single crystal substrate 57 may be changed as appropriate depending on the required pass characteristics of the acoustic wave filter 1. Even an acoustic wave resonator using a LiTaO piezoelectric substrate having a cut angle other than the above-described cut angle can achieve the same effects as the acoustic wave resonator 60 using the piezoelectric film 53.

[0059] The piezoelectric substrate on which the IDT electrode 54 is formed may have a structure in which a support substrate, an energy trapping layer, and a piezoelectric film are laminated in this order. The IDT electrode 54 is formed on the piezoelectric film. The piezoelectric film may be made of, for example, a LiTaO3 piezoelectric single crystal or a piezoelectric ceramic. The support substrate is a substrate that supports the piezoelectric film, the energy trapping layer, and the IDT electrode 54.

[0060] The energy trapping layer is composed of one or more layers, and the velocity of the bulk acoustic waves propagating through at least one of the layers is greater than the velocity of the acoustic waves propagating near the piezoelectric film. For example, the energy trapping layer may have a laminated structure of a low acoustic velocity layer and a high acoustic velocity layer. The low acoustic velocity layer is a film in which the acoustic velocity of the bulk waves in the low acoustic velocity layer is slower than the acoustic velocity of the acoustic waves propagating through the piezoelectric film. The high acoustic velocity layer is a film in which the acoustic velocity of the bulk waves in the high acoustic velocity layer is faster than the acoustic velocity of the acoustic waves propagating through the piezoelectric film. The support substrate may also be the high acoustic velocity layer.

[0061] The energy trapping layer may also be an acoustic impedance layer having a configuration in which low acoustic impedance layers with a relatively low acoustic impedance and high acoustic impedance layers with a relatively high acoustic impedance are alternately stacked.

[0062] 3C is a cross-sectional view schematically illustrating a third example of an acoustic wave resonator 60 included in the acoustic wave filter 1 according to the embodiment. In FIG. 3C, an acoustic wave resonator using a laminate including a piezoelectric layer 67, a lower electrode 66, and an upper electrode 68 is illustrated as the acoustic wave resonator of the acoustic wave filter 1. As illustrated in the drawing, the acoustic wave resonator includes, for example, a support substrate 65, a lower electrode 66, a piezoelectric layer 67, and an upper electrode 68, and is configured such that the support substrate 65, the lower electrode 66, the piezoelectric layer 67, and the upper electrode 68 are laminated in this order.

[0063] The support substrate 65 is a substrate, such as a silicon substrate, for supporting the lower electrode 66, the piezoelectric layer 67, and the upper electrode 68. The support substrate 65 has a cavity in the region that contacts the lower electrode 66. This allows the piezoelectric layer 67 to vibrate freely.

[0064] The lower electrode 66 is an example of a first planar electrode, and is formed on one surface of the support substrate 65. The upper electrode 68 is an example of a second planar electrode, and is formed on one surface of the support substrate 65. The lower electrode 66 and the upper electrode 68 are made of a material such as Al containing 1% Cu.

[0065] The piezoelectric layer 67 is an example of a piezoelectric thin film, and is formed between the lower electrode 66 and the upper electrode 68. The piezoelectric layer 67 is mainly composed of at least one of ZnO (zinc oxide), AlN (aluminum nitride), PZT (lead zirconate titanate), KN (potassium niobate), LN (lithium niobate), LT (lithium tantalate), quartz crystal, and LiBO (lithium borate).

[0066] The elastic wave resonator having the above-described laminated structure generates resonance by inducing elastic waves in the piezoelectric layer 67 when electrical energy is applied between the lower electrode 66 and the upper electrode 68. The elastic waves generated by this elastic wave resonator propagate between the lower electrode 66 and the upper electrode 68 in a direction perpendicular to the film surface of the piezoelectric layer 67.

[0067] 1 and 2 includes a support substrate 65. Each of the functional electrodes 31 and 32 includes, in order from the principal surface 70a, a lower electrode 66, a piezoelectric layer 67, and an upper electrode 68. Note that the lower electrode 66 and the upper electrode 68 included in each of the functional electrodes 31 and 32 are limited to a portion that overlaps with the piezoelectric layer 67 when the principal surface 70a is viewed in plan.

[0068] [3. Structure of Acoustic Wave Filter 1A According to Modification 1] Next, the structure of an acoustic wave filter 1A according to Modification 1 will be described. Fig. 4 is a plan view of acoustic wave filter 1A according to Modification 1 of an embodiment. Acoustic wave filter 1A according to Modification 1 is an example of an acoustic wave device, and includes substrates 10 and 70, walls 21A, 22 to 25, functional electrodes 31 and 32, signal conductors 35 and 36, via conductor 11, connecting lines 33, 34, 37 and 38, insulating film 13, planar electrode 12, and bump electrode 40.

[0069] Although not shown in Figure 4, the substrate 10, walls 23 to 25, via conductor 11, connection wiring 33, 34, 37 and 38, insulating film 13, planar electrode 12, and bump electrode 40 have the same arrangement as that shown in Figure 1.

[0070] The elastic wave filter 1A according to this modification is different from the elastic wave filter 1 according to the embodiment in the configuration of the wall 21A and the arrangement of the functional electrodes 31 and 32. Therefore, the following description of the elastic wave filter 1A according to this modification will omit a description of the same configuration as that of the elastic wave filter 1 according to the embodiment and will focus on the different configuration.

[0071] The wall 22 is an example of a first wall, and is disposed between the principal surfaces 10a and 70a so as to surround the functional electrodes 31 and 32 when the principal surfaces 10a and 70a are viewed in plan, as shown in FIG.

[0072] Wall 21A is an example of a second wall, and as shown in FIG. 4, is arranged to surround wall 22 via gap 81 in the plan view. Wall 21A has openings 80A and 80B that penetrate between inner circumferential surface 21a and outer circumferential surface 21b and communicate with gap 81, as shown in FIG. 4. Opening 80A is an example of a first opening, and has an opening diameter G A The opening 80B is an example of a second opening, and has an opening diameter G B It should be noted that there needs to be at least one opening 80A and at least one opening 80B.

[0073] As shown in FIG. 4, the distance between the opening 80A and the functional electrodes 31 and 32 is smaller than the distance between the opening 80B and the functional electrodes 31 and 32. A is the opening diameter G of the opening 80B B is greater than.

[0074] As a result, the temperature of the wall 22 increases in areas closer to the functional electrodes 31 and 32, which are heat-generating elements. However, among the multiple openings provided in the wall 21A, the opening 80A closer to the functional electrodes 31 and 32 has a larger opening diameter than the opening 80B farther from the functional electrodes 31 and 32, which increases the air flow rate in the gap 81 closer to the functional electrodes 31 and 32. This enhances heat dissipation in the portion of the wall 22 closer to the functional electrodes 31 and 32, thereby providing an acoustic wave filter 1A with improved heat dissipation properties.

[0075] The distance between the opening and the functional electrode is defined as the minimum distance between the opening and the functional electrode. When the functional electrode is an IDT electrode formed on a piezoelectric substrate as shown in FIG. 3A, the functional electrode includes electrode fingers but does not include busbar electrodes. When the functional electrode is a laminate of a piezoelectric layer, an upper electrode, and a lower electrode as shown in FIG. 3C, the functional electrode includes the piezoelectric layer and portions of the upper electrode and lower electrode that overlap with the piezoelectric layer. When multiple functional electrodes are arranged, the distance between the opening and the functional electrode is defined as the minimum distance between the opening and each functional electrode.

[0076] [4. Structure of Acoustic Wave Filter 1B According to Modification 2] Next, the structure of an acoustic wave filter 1B according to Modification 2 will be described. Fig. 5 is a plan view of an acoustic wave filter 1B according to Modification 2 of an embodiment. The acoustic wave filter 1B according to Modification 2 is an example of an acoustic wave device, and includes substrates 10 and 70, walls 21B, 22 to 25, a functional electrode 31, a signal conductor 35, a via conductor 11, connecting lines 33 and 37, an insulating film 13, a planar electrode 12, and a bump electrode 40.

[0077] Although not shown in Figure 5, the substrate 10, walls 23 to 25, via conductor 11, connection wiring 33 and 37, insulating film 13, planar electrode 12, and bump electrode 40 have the same arrangement as that shown in Figure 1.

[0078] The acoustic wave filter 1B according to this modification is different from the acoustic wave filter 1 according to the embodiment mainly in the configuration of the wall 21B and in the absence of the functional electrode 32. Therefore, the following description of the acoustic wave filter 1B according to this modification will omit a description of the same configuration as the acoustic wave filter 1 according to the embodiment and will focus on the different configuration.

[0079] The wall 22 is an example of a first wall, and as shown in FIG. 5, is disposed between the principal surfaces 10a and 70a so as to surround the functional electrode 31 when the principal surfaces 10a and 70a are viewed in plan.

[0080] Wall 21B is an example of a second wall, and as shown in FIG. 5, is arranged on the outer periphery of wall 22 along a portion of wall 22 via gap 81 in the plan view. Gap 81 communicates with the outer periphery of wall 21B via both ends of wall 21B in the plan view. In this modification, wall 21B is composed of two walls arranged along two adjacent sides of four sides of substrate 70, which has a rectangular shape in the plan view. Wall 21B need not completely surround wall 22; for example, it may have one wall arranged along one side of the four sides of substrate 70, which has a rectangular shape, and no walls along the remaining three sides.

[0081] According to the above configuration, an air flow (air current) is generated in the gap 81 due to a temperature difference between the wall 22, which is in contact with the internal space in which the functional electrode 31 (heat generating element) is disposed, and the wall 21B, which is in contact with the external space. That is, the heat generated by the wall 22 can be efficiently dissipated to the external space of the wall 21B via both ends of the wall 21B by the air flow in the gap 81. This provides an acoustic wave filter 1B with improved heat dissipation. Furthermore, because a portion of the frame surrounding the functional electrode has a double structure including the walls 21B and 22, the mechanical strength of the frame as a support is increased, thereby enabling the mechanical strength of the acoustic wave filter 1B to be improved.

[0082] [5. Structure of Acoustic Wave Filter 1C According to Modification 3] Next, the structure of an acoustic wave filter 1C according to Modification 3 will be described. Fig. 6 is a cross-sectional view of the acoustic wave filter 1C according to Modification 3 of an embodiment. Fig. 7 is a plan ... (transparent view) of a cross section taken along line VII-VII in Fig. 6, viewed from the positive side of the z-axis. Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 7, viewed from the negative side of the y-axis.

[0083] 6 and 7 , the acoustic wave filter 1C is an example of an acoustic wave device and includes substrates 10 and 70, a frame 20C, functional electrodes 31 and 32, signal conductors 35 and 36, a via conductor 11, connection wirings 33, 34, 37, and 38, an insulating film 13, a planar electrode 12, and a bump electrode 40. The acoustic wave filter 1C according to this modification has a different frame 20C configuration than the acoustic wave filter 1 according to the embodiment. Therefore, the following description of the acoustic wave filter 1C according to this modification will focus on the different configuration and omit a description of the same configuration as the acoustic wave filter 1 according to the embodiment.

[0084] The frame 20C is disposed between the main surfaces 10a and 70a and includes walls 21C, 22C, 23, 24, and 25.

[0085] The wall 22C is an example of a first wall, and is disposed between the principal surfaces 10a and 70a so as to surround the functional electrodes 31 and 32 when the principal surfaces 10a and 70a are viewed in plan view, as shown in FIG.

[0086] Wall 21C is an example of a second wall, and as shown in Fig. 7, is arranged to surround wall 22C via gap 81 in the plan view. Wall 21C has opening 80 that penetrates between inner circumferential surface 21a and outer circumferential surface 21b and communicates with gap 81, as shown in Fig. 7. It is sufficient that there is at least one opening 80.

[0087] The walls 21C and 22C include a conductor portion whose main component is, for example, aluminum (Al). Each of the walls 21C and 22C may include a conductor portion made of a metal.

[0088] The wall 22C separates the internal space, in which the functional electrodes 31 and 32 are formed, from the external space. Furthermore, since the walls 22C and 23 to 25 include a conductor made of metal, it is possible to ensure the airtightness of the internal space with high precision.

[0089] According to the above configuration, a temperature difference between the wall 22C, which is in contact with the internal space in which the heat-generating functional electrodes 31 and 32 are disposed, and the wall 21C, which is in contact with the external space, generates an airflow (air current) in the gap 81 and the opening 80. That is, the heat generated by the wall 22C can be efficiently dissipated to the external space of the wall 21C via the airflow in the gap 81 through the opening 80. This allows the acoustic wave filter 1C to have improved heat dissipation. Furthermore, the provision of multiple openings 80 communicating with the gap 81 increases the air flow rate and flow velocity in the gap 81, thereby enabling more efficient dissipation of heat generated by the wall 22C to the external space of the wall 21C. Furthermore, the frame 20C has a double structure including the walls 21C and 22C, which enhances the mechanical strength of the frame 20C as a support, thereby enhancing the mechanical strength of the acoustic wave filter 1C.

[0090] Next, the surface structure of frame 20C will be described. Fig. 8A is a diagram showing an electron microscope image of the outer cross section and outer surface of wall 22C according to Modification 3 of the embodiment. Fig. 8B is a diagram showing an electron microscope image of the inner cross section and inner surface of wall 22C according to Modification 3 of the embodiment.

[0091] The wall 22C includes a conductor mainly composed of aluminum (Al) and isolates the internal space of the wall 22C from the external space. Therefore, by exposing the acoustic wave filter 1C to a high-temperature steam atmosphere during the manufacturing process of the acoustic wave filter 1C, boehmite (AlO(OH):alumina monohydrate) can be produced on the external surface of the wall 22C, which is the internal surface serving as the inner peripheral side wall of the wall 22C and the external surface serving as the outer peripheral side wall of the wall 22C. In other words, the external surface of the wall 22C contains boehmite. FIG. 8A shows that boehmite is formed on the external surface of the wall 22C. Boehmite has an orthorhombic needle-like crystal structure, and the length of the needle-like crystals in the short direction is approximately 10 nm. This results in an uneven external surface of the wall 22C.

[0092] On the other hand, the inner surface of the wall body 22C is not exposed to a high-temperature water vapor atmosphere during the manufacturing process of the acoustic wave filter 1C, so as shown in FIG. 8B, boehmite is not formed on the inner surface, and the inner surface has a smaller unevenness difference than the outer surface.

[0093] Therefore, the outer surface of the wall 22C is rougher than the inner surface of the wall 22C. This prevents heat generated in the functional electrodes 31 and 32 from being dissipated from the inner surface of the wall 22C into the internal space of the wall 22C, and allows the heat to be efficiently dissipated from the outer surface of the wall 22C to the outside of the acoustic wave filter 1C. This makes it possible to provide an acoustic wave filter 1C with improved heat dissipation properties.

[0094] The outer surface of the wall 22C may contain aluminum oxide or aluminum hydroxide instead of boehmite. The aluminum oxide or aluminum hydroxide formed on the outer surface of the wall 22C has an uneven structure, so that the outer surface of the wall 22C is rougher than the inner surface of the wall 22C. This makes it possible to provide an acoustic wave filter 1C with improved heat dissipation.

[0095] Furthermore, the outer surface of the wall 22C is rougher than the inner surface of the wall 22C; in other words, the surface area of ​​a given region on the outer surface of the wall 22C is greater than the surface area of ​​the given region on the inner surface of the wall 22C.

[0096] This configuration allows the outer surface of the wall 22C to have a larger heat dissipation area than the inner surface of the wall 22C, thereby preventing heat generated in the functional electrodes 31 and 32 from being dissipated from the inner surface of the wall 22C into the internal space of the wall 22C, and allowing the heat to be efficiently dissipated from the outer surface of the wall 22C to the outside of the acoustic wave filter 1C. This makes it possible to provide an acoustic wave filter 1C with improved heat dissipation properties.

[0097] FIG. 9 illustrates a method for evaluating the surface area of ​​a wall 22C according to a third modification of the embodiment. This figure shows schematic cross-sectional views of the outer and inner sides of the wall 22C. The surface area of ​​a predetermined region on the outer surface of the wall 22C can be evaluated by the sum of the lengths of the ridges and valleys of the concave-convex shape of a line segment extending from the upper end to the lower end of the predetermined region on the outer surface of the wall 22C in the z-axis direction (concave-convex length L1). The surface area of ​​the predetermined region on the inner surface of the wall 22C can be evaluated by the sum of the lengths of the ridges and valleys of the concave-convex shape of a line segment extending from the upper end to the lower end of the predetermined region on the inner surface of the wall 22C in the z-axis direction (concave-convex length L2). In the acoustic wave filter 1C according to this modification, the concave-convex length L1 is greater than the concave-convex length L2.

[0098] The specified area on the outer surface is defined as an area having a specified area when the outer surface of wall 22C is viewed in a plane with the negative x-axis direction in Figure 9 as the normal direction, and the specified area on the inner surface is defined as an area having the above-mentioned specified area when the inner surface of wall 22C is viewed in a plane with the positive x-axis direction in Figure 9 as the normal direction.

[0099] Furthermore, the outer surface of wall 22C is rougher than the inner surface of wall 22C; in other words, the arithmetic mean roughness of a given area on the outer surface of wall 22C is greater than the arithmetic mean roughness of the given area on the inner surface of wall 22C.

[0100] This configuration allows the outer surface of the wall 22C to have a larger heat dissipation area than the inner surface of the wall 22C, and therefore allows heat generated in the functional electrodes 31 and 32 to be efficiently dissipated from the outer surface of the wall 22C to the outside of the acoustic wave filter 1C through the gap 81 and the opening 80. This makes it possible to provide an acoustic wave filter 1C with improved heat dissipation properties.

[0101] 7, the outer and inner surfaces of the wall 21C according to this modification may be rougher than the inner surface of the wall 22C. Because the wall 21C has the openings 80, boehmite can be generated on the inner and outer surfaces of the wall 21C by exposing the acoustic wave filter 1C to a high-temperature water vapor atmosphere during the manufacturing process of the acoustic wave filter 1C, for example.

[0102] This allows the heat on the outer surface of the wall 22C to be absorbed by the wall 21C, thereby enabling more efficient heat dissipation to the outside of the acoustic wave filter 1C.

[0103] Furthermore, the outer and inner surfaces of wall 21C are rougher than the inner surface of wall 22C; in other words, the surface area of ​​a given region on the outer and inner surfaces of wall 21C is greater than the surface area of ​​the given region on the inner surface of wall 22C.

[0104] Furthermore, the outer and inner surfaces of wall 21C are rougher than the inner surface of wall 22C; in other words, the arithmetic mean roughness of a given area on the outer and inner surfaces of wall 21C is greater than the arithmetic mean roughness of the given area on the inner surface of wall 22C.

[0105] The arithmetic mean roughness of the surfaces of the walls 21C and 22C can be measured using a laser microscope (for example, Olympus OLS5000). If the outer periphery of the wall 21C is in contact with a resin member, the resin member can be removed using fuming nitric acid or a heat gun, and then the arithmetic mean roughness can be measured using the laser microscope.

[0106] The arithmetic mean roughness of a predetermined region on the outer surface of the wall body 22C is preferably 10 nm or more. This is because the length of the short side of the needle-like crystals of boehmite formed on the outer peripheral surface of the wall body 22C is about 10 nm. This promotes heat dissipation from the outer surface of the wall body 22C.

[0107] The acoustic wave filter 1C according to this modification satisfies at least one of the following conditions: (1) the surface area of ​​a predetermined region on the outer surface of the wall 22C is larger than the surface area of ​​the predetermined region on the inner surface of the wall 22C, and (2) the arithmetic mean roughness of the outer surface of the wall 22C is larger than the arithmetic mean roughness of the inner surface of the wall 22C. This makes it possible to provide an acoustic wave filter 1C with improved heat dissipation.

[0108] The outer surface of the wall 22C may be rougher than the surfaces of the signal conductors 35 and 36. This allows heat generated in the functional electrodes 31 and 32 to be efficiently dissipated from the outer surface of the wall 22C to the outside of the acoustic wave filter 1C while suppressing heat dissipation from the surfaces of the signal conductors 35 and 36 into the internal space of the wall 22C. This makes it possible to provide an acoustic wave filter 1C with improved heat dissipation properties.

[0109] [6 Effects etc.] As described above, the acoustic wave filter 1 according to this embodiment includes the substrate 10 having principal surfaces 10a and 10b facing each other, the substrate 70 having the principal surface 70a facing the principal surface 10a, the functional electrodes 31 and 32 arranged on the principal surface 70a, and the frame body 20 arranged between the principal surfaces 10a and 70a. The frame body 20 includes the wall body 22 that surrounds the functional electrodes 31 and 32 when the principal surfaces 10a and 70a are viewed in a plane, and the wall body 21 that is arranged on the outer periphery of the wall body 22 with a gap 81 interposed therebetween when viewed in the plane. The wall body 21 has at least one opening 80 that penetrates between the inner circumferential surface 21a and the outer circumferential surface 21b and communicates with the gap 81.

[0110] This generates an airflow in the gap 81 and the opening 80 due to a temperature difference between the wall 22, which is in contact with the internal space in which the heat-generating functional electrodes 31 and 32 are disposed, and the wall 21, which is in contact with the external space. That is, the heat of the wall 22 can be efficiently dissipated to the external space of the wall 21 via the opening 80 due to the airflow in the gap 81. This makes it possible to provide an acoustic wave filter 1 with improved heat dissipation properties.

[0111] Furthermore, for example, in the acoustic wave filter 1, the wall 21 is disposed to surround the wall 22 with the gap 81 interposed therebetween in the plan view.

[0112] With this, wall 22 is surrounded by gap 81, allowing heat to be efficiently dissipated to the external space from the entire outer circumferential surface of wall 22. Furthermore, because frame 20 has a double structure including walls 21 and 22, the mechanical strength of frame 20 as a support is increased, thereby enabling the mechanical strength of acoustic wave filter 1 to be increased.

[0113] Furthermore, for example, in the acoustic wave filter 1, the wall 21 has a plurality of openings 80 that communicate with the gap 81.

[0114] This allows the air flow rate and flow velocity in the gap 81 to be increased, so that the heat held by the wall 22 can be dissipated to the space outside the wall 21 more efficiently.

[0115] Furthermore, for example, in the acoustic wave filter 1A according to the first modification, the plurality of openings include openings 80A and 80B, the distance between the opening 80A and the functional electrodes 31 and 32 is smaller than the distance between the opening 80B and the functional electrodes 31 and 32, and the opening diameter G A is the opening diameter G of the opening 80B B is greater than.

[0116] The temperature of the wall 22 increases in portions closer to the functional electrodes 31 and 32, which are heat-generating bodies. As a result, the opening 80A closer to the functional electrodes 31 and 32 has a larger opening diameter than the opening 80B farther from the functional electrodes 31 and 32, which increases the air flow rate in the gap 81 closer to the functional electrodes 31 and 32. This enhances heat dissipation in the portion of the wall 22 closer to the functional electrodes 31 and 32, thereby providing an acoustic wave filter 1A with improved heat dissipation properties.

[0117] An acoustic wave filter 1B according to the second modification includes a substrate 10 having principal surfaces 10a and 10b facing each other, a substrate 70 having a principal surface 70a facing the principal surface 10a, functional electrodes 31 and 32 arranged on the principal surface 70a, and a frame body arranged between the principal surfaces 10a and 70a, the frame body including a wall body 22 that surrounds the functional electrodes 31 and 32 when the principal surfaces 10a and 70a are viewed in a plane, and a wall body 21B that is arranged along a part of the wall body 22 on the periphery of the wall body 22 with a gap 81 interposed therebetween, and the gap 81 communicates with the peripheral region of the wall body 21B via both ends of the wall body 21B in the planar view.

[0118] This generates an airflow in the gap 81 due to a temperature difference between the wall 22, which is in contact with the internal space in which the functional electrode 31, which is a heat-generating body, is disposed, and the wall 21B, which is in contact with the external space. That is, the heat of the wall 22 can be efficiently dissipated to the external space of the wall 21B via both ends of the wall 21B by the airflow in the gap 81. This makes it possible to provide an acoustic wave filter 1B with improved heat dissipation properties.

[0119] Furthermore, for example, in an acoustic wave filter 1C according to the third modification, the outer surface of the wall 22C is rougher than the inner surface of the wall 22C.

[0120] This configuration allows heat generated in the functional electrodes 31 and 32 to be efficiently dissipated from the outer surface of the wall 22C to the outside of the wall 22C while suppressing heat dissipation into the internal space of the wall 22C, thereby providing an acoustic wave filter 1C with improved heat dissipation properties.

[0121] Furthermore, for example, in acoustic wave filter 1C, wall 22C includes a conductor portion made of metal.

[0122] This makes it possible to improve the airtightness of the internal space of the wall body 22C. Also, by setting the wall body 22C to, for example, ground potential, it becomes possible to block external noise.

[0123] In addition, for example, in acoustic wave filter 1C, the conductor portion of wall 22C is made of aluminum.

[0124] According to this, in the manufacturing process of the acoustic wave filter 1C, aluminum oxide, aluminum hydroxide, and the like can be generated on the outer surface of the wall body 22C by subjecting the acoustic wave filter 1C to a high-temperature water vapor atmosphere, thereby forming an uneven structure on the outer surface of the wall body 22C.

[0125] In addition, for example, in the acoustic wave filter 1C, the outer surface of the wall 22C contains aluminum oxide.

[0126] This allows the formation of an uneven structure on the outer surface of the wall body 22C.

[0127] In addition, for example, in the acoustic wave filter 1C, the outer surface of the wall 22C contains boehmite.

[0128] This results in an uneven structure resulting from the needle-like crystal structure on the outer surface of the wall 22C, making the outer surface rougher than the inner surface. This prevents heat generated in the functional electrodes 31 and 32 from being dissipated into the interior space of the wall 22C, and allows efficient heat dissipation from the outer surface of the wall 22C to the outside of the acoustic wave filter 1C. This makes it possible to provide an acoustic wave filter 1C with improved heat dissipation properties.

[0129] Furthermore, for example, in acoustic wave filter 1C, the outer surface of wall 22C contains aluminum hydroxide.

[0130] This allows the formation of an uneven structure on the outer surface of the wall body 22C.

[0131] Furthermore, for example, in the acoustic wave filter 1C, the surface area of ​​a predetermined region on the outer surface of the wall 22C is larger than the surface area of ​​the predetermined region on the inner surface of the wall 22C.

[0132] In addition, for example, in the acoustic wave filter 1C, the arithmetic mean roughness of a predetermined region on the outer surface of the wall 22C is greater than the arithmetic mean roughness of the predetermined region on the inner surface of the wall 22C.

[0133] As a result, the outer surface of the wall 22C has a larger heat dissipation area than the inner surface of the wall 22C, and heat generated in the functional electrodes 31 and 32 can be efficiently dissipated from the outer surface of the wall 22C to the outside of the acoustic wave filter 1C, thereby providing an acoustic wave filter 1C with improved heat dissipation properties.

[0134] Furthermore, for example, in the acoustic wave filter 1C, the outer and inner surfaces of the wall 21C are rougher than the inner surface of the wall 22C.

[0135] This allows the wall 21C to efficiently absorb heat from the outer surface of the wall 22C, thereby enabling more efficient heat dissipation to the outside of the acoustic wave filter 1C.

[0136] Also, for example, in the acoustic wave filter 1 (and 1A, 1B, 1C), the frame 20 (and 20C) further includes walls 23 and 25 arranged between the main surface 10a and the walls 21 and 22 and joined to the main surface 10a and the walls 21 and 22.

[0137] For example, the acoustic wave filter 1 (and 1A, 1B, and 1C) further includes a signal conductor 35 connected to the functional electrode 31, arranged inside the frame body 20 (and 20C) when the main surfaces 10a and 70a are viewed in plan, and in contact with the main surfaces 10a and 70a, and a via conductor 11 arranged on the substrate 10 from the main surfaces 10a to 10b and connected to the signal conductor 35.

[0138] This allows signals passing through the functional electrode 31 to be transmitted through the via conductors 11 to the main surface 10b side.

[0139] Furthermore, for example, in the acoustic wave filters 1 (and 1A, 1B, and 1C), the substrate 10 includes silicon.

[0140] This improves the thermal conductivity and heat dissipation of the acoustic wave filter 1 (and 1A, 1B, and 1C) compared to when the substrate 10 is made of a resin material. In addition, the processing accuracy of the substrate 10 is improved.

[0141] Furthermore, for example, in the acoustic wave filter 1 (and 1A, 1B, and 1C), the substrate 70 has piezoelectricity, an IDT electrode is arranged on the main surface 70a, the IDT electrode has a plurality of electrode fingers 61a and 61b arranged parallel to each other, a busbar electrode 62a configured to connect one ends of the plurality of electrode fingers 61a, and a busbar electrode 62b configured to connect one ends of the electrode fingers 61b and arranged opposite the busbar electrode 62a across the plurality of electrode fingers 61a and the plurality of electrode fingers 61b, and the functional electrodes 31 and 32 include a plurality of electrode fingers 61a and a plurality of electrode fingers 61b.

[0142] This makes it possible to improve heat dissipation in acoustic wave filter 1 (and 1A, 1B, and 1C) that performs electromechanical transduction using IDT electrodes.

[0143] Furthermore, for example, in the acoustic wave filters 1 (and 1A, 1B, and 1C), the functional electrodes 31 and 32 include a lower electrode 66, a piezoelectric layer 67, and an upper electrode 68 in this order from the principal surface 70a.

[0144] This allows for improved heat dissipation in the acoustic wave filter 1 (and 1A, 1B, and 1C) that performs electromechanical transduction using the piezoelectric layer 67, the lower electrode 66, and the upper electrode 68.

[0145] In addition, for example, in the acoustic wave filter 1C, the substrate 70 includes silicon.

[0146] This allows the substrate 70 to be used as a support substrate for an elastic wave resonator using the laminate.

[0147] (Other embodiments) Although the elastic wave device according to the present invention has been described above with reference to the embodiments and modifications thereof, the present invention is not limited to the above embodiments and modifications. The present invention also includes modifications that can be made by those skilled in the art without departing from the spirit of the present invention, as well as various devices incorporating the elastic wave device according to the present invention.

[0148] For example, although an acoustic wave filter has been given as an example of an acoustic wave device in the above-described embodiment and modifications, an acoustic wave device according to the present invention may also be an acoustic wave resonator having one or more functional electrodes.

[0149] The features of the acoustic wave devices described based on the above-described embodiment and modifications will be described below.

[0150] <1> a first substrate having a first main surface and a second main surface facing each other; a second substrate having a third main surface facing the first main surface; a functional electrode disposed on the third principal surface; a frame body disposed between the first main surface and the third main surface, The frame body is a first wall surrounding the functional electrode when the first principal surface and the third principal surface are viewed in plan; a second wall body disposed on an outer periphery of the first wall body via a gap in the plan view, The second wall has at least one opening that penetrates between the inner circumferential surface and the outer circumferential surface and communicates with the gap.

[0151] <2> the second wall is disposed so as to surround the first wall via the gap in the plan view. <1> The acoustic wave device according to claim 1.

[0152] <3> The second wall has a plurality of the openings communicating with the gap. <1> or <2> The acoustic wave device according to claim 1.

[0153] <4> the plurality of openings include a first opening and a second opening; a distance between the first opening and the functional electrode is smaller than a distance between the second opening and the functional electrode; The opening diameter of the first opening is larger than the opening diameter of the second opening. <3> The acoustic wave device according to claim 1.

[0154] <5> a first substrate having a first main surface and a second main surface facing each other; a second substrate having a third main surface facing the first main surface; a functional electrode disposed on the third principal surface; a frame body disposed between the first main surface and the third main surface, The frame body is a first wall surrounding the functional electrode when the first principal surface and the third principal surface are viewed in plan; a second wall body disposed along a part of the first wall body on an outer periphery of the first wall body with a gap therebetween in the plan view, In the plan view, the gap communicates with an outer peripheral region of the second wall body via both ends of the second wall body.

[0155] <6> an outer surface of the first wall being rougher than an inner surface of the first wall; <1> ~ <5> 10. The acoustic wave device according to claim 9, wherein

[0156] <7> The first wall includes a conductor portion made of metal. <6> The acoustic wave device according to claim 1.

[0157] <8> The conductor portion is made of aluminum. <7> The acoustic wave device according to claim 1.

[0158] <9> the outer surface of the first wall comprises aluminum oxide; <8> The acoustic wave device according to claim 1.

[0159] <10> The outer surface of the first wall comprises boehmite. <9> The acoustic wave device according to claim 1.

[0160] <11> The outer surface of the first wall comprises aluminum hydroxide. <7> The acoustic wave device according to claim 1.

[0161] <12> The surface area of ​​a predetermined region on the outer surface of the first wall is larger than the surface area of ​​the predetermined region on the inner surface of the first wall. <6> ~ <11> 10. The acoustic wave device according to claim 9, wherein

[0162] <13> the arithmetic mean roughness of a predetermined area on the outer surface of the first wall body is greater than the arithmetic mean roughness of the predetermined area on the inner surface of the first wall body; <6> ~ <11> 10. The acoustic wave device according to claim 9, wherein

[0163] <14> the outer and inner surfaces of the second wall are rougher than the inner surface of the first wall; <6> ~ <13> 10. The acoustic wave device according to claim 9, wherein

[0164] <15> The frame further includes: a third wall body disposed between the first main surface and the first and second walls and joined to the first main surface, the first wall body, and the second wall body; <1> ~ <14> 10. The acoustic wave device according to claim 9, wherein

[0165] <16> moreover, a first conductor connected to the functional electrode, disposed inside the frame in the plan view, and in contact with the first principal surface and the third principal surface; a via conductor disposed on the first substrate from the first main surface toward the second main surface and connected to the first conductor; <1> ~ <15> 10. The acoustic wave device according to claim 9, wherein

[0166] <17> the first substrate comprises silicon; <1> ~ <16> 10. The acoustic wave device according to claim 9, wherein

[0167] <18> the second substrate has piezoelectric properties; an IDT electrode is disposed on the third principal surface; The IDT electrode is a plurality of first electrode fingers and a plurality of second electrode fingers arranged parallel to each other; a first bus bar electrode configured to connect one ends of the plurality of first electrode fingers to each other; a second bus bar electrode configured to connect one ends of the second electrode fingers to each other and disposed opposite the first bus bar electrode with the first electrode fingers and the second electrode fingers interposed therebetween, the functional electrode includes the plurality of first electrode fingers and the plurality of second electrode fingers; <1> ~ <17> 10. The acoustic wave device according to claim 9, wherein

[0168] <19> the functional electrode includes, in order from the third principal surface, a first planar electrode, a piezoelectric thin film, and a second planar electrode; <1> ~ <17> 10. The acoustic wave device according to claim 9, wherein

[0169] <20> the second substrate comprises silicon; <19> The acoustic wave device according to claim 1. [Industrial Applicability]

[0170] The present invention can be widely used as a small acoustic wave filter in communication devices such as mobile phones. [Explanation of symbols]

[0171] 1, 1A, 1B, 1C Acoustic Wave Filters 10, 70 board 10a, 10b, 70a, 70b main surface 11 Via conductor 12 Planar electrode 13 Insulating film 20, 20C frame 21, 21A, 21B, 21C, 22, 22C, 23, 24, 25 Wall 21a Inner surface 21b Outer surface 31, 32 Functional electrodes 33, 34, 37, 38 Connection wiring 35, 36 Signal conductors 40 Bump electrode 50 Piezoelectric substrate 51 High-sonic support substrate 52 Low sound velocity membrane 53 Piezoelectric film 54 IDT electrode 55, 58 protective layer 57 Piezoelectric single crystal substrate 60 Elastic wave resonator 60a, 60b comb-shaped electrode 61a, 61b electrode fingers 62a, 62b Busbar electrodes 65 Support substrate 66 Lower electrode 67 Piezoelectric layer 68 Upper electrode 80, 80A, 80B opening 81 void 540 Adhesion layer 542 Main electrode layer

Claims

1. a first substrate having a first main surface and a second main surface facing each other; a second substrate having a third main surface facing the first main surface; a functional electrode disposed on the third principal surface; a frame body disposed between the first main surface and the third main surface, The frame body is a first wall surrounding the functional electrode when the first principal surface and the third principal surface are viewed in plan; a second wall body disposed on an outer periphery of the first wall body via a gap in the plan view, The second wall has at least one opening extending between an inner circumferential surface and an outer circumferential surface and communicating with the gap. Elastic wave device.

2. the second wall is disposed to surround the first wall via the gap in the plan view. The acoustic wave device according to claim 1 .

3. The second wall has a plurality of openings communicating with the gap. The acoustic wave device according to claim 1 .

4. the plurality of openings include a first opening and a second opening; a distance between the first opening and the functional electrode is smaller than a distance between the second opening and the functional electrode; The opening diameter of the first opening is larger than the opening diameter of the second opening. The acoustic wave device according to claim 3 .

5. a first substrate having a first main surface and a second main surface facing each other; a second substrate having a third main surface facing the first main surface; a functional electrode disposed on the third principal surface; a frame body disposed between the first main surface and the third main surface, The frame body is a first wall surrounding the functional electrode when the first principal surface and the third principal surface are viewed in plan; a second wall body disposed along a part of the first wall body on an outer periphery of the first wall body with a gap interposed therebetween in the plan view, In the plan view, the gap communicates with an outer peripheral region of the second wall body via both ends of the second wall body. Elastic wave device.

6. an outer surface of the first wall being rougher than an inner surface of the first wall; The acoustic wave device according to any one of claims 1 to 5.

7. The first wall includes a conductor portion made of metal. The acoustic wave device according to claim 6 .

8. The conductor portion is made of aluminum. The acoustic wave device according to claim 7 .

9. the outer surface of the first wall comprises aluminum oxide; The acoustic wave device according to claim 8 .

10. The outer surface of the first wall comprises boehmite. The acoustic wave device according to claim 9 .

11. the outer surface of the first wall comprises aluminum hydroxide; The acoustic wave device according to claim 7 .

12. a surface area of ​​a predetermined region on the outer surface of the first wall body is larger than a surface area of ​​the predetermined region on the inner surface of the first wall body; The acoustic wave device according to claim 6 .

13. an arithmetic mean roughness of a predetermined region on the outer surface of the first wall body is greater than an arithmetic mean roughness of the predetermined region on the inner surface of the first wall body; The acoustic wave device according to claim 6 .

14. the outer and inner surfaces of the second wall are rougher than the inner surface of the first wall; The acoustic wave device according to claim 6 .

15. The frame further includes: a third wall body disposed between the first main surface and the first and second walls and joined to the first main surface, the first wall body, and the second wall body; The acoustic wave device according to any one of claims 1 to 5.

16. moreover, a first conductor connected to the functional electrode, disposed inside the frame body in the plan view, and in contact with the first principal surface and the third principal surface; a via conductor disposed on the first substrate from the first main surface toward the second main surface and connected to the first conductor, The acoustic wave device according to any one of claims 1 to 5.

17. the first substrate comprises silicon; The acoustic wave device according to any one of claims 1 to 5.

18. the second substrate has piezoelectric properties; an IDT electrode is disposed on the third main surface; The IDT electrode is a plurality of first electrode fingers and a plurality of second electrode fingers arranged parallel to each other; a first bus bar electrode configured to connect one ends of the plurality of first electrode fingers to each other; a second bus bar electrode configured to connect one ends of the second electrode fingers to each other and disposed opposite the first bus bar electrode with the first electrode fingers and the second electrode fingers interposed therebetween, the functional electrode includes the plurality of first electrode fingers and the plurality of second electrode fingers; The acoustic wave device according to any one of claims 1 to 5.

19. the functional electrode includes, in order from the third principal surface, a first planar electrode, a piezoelectric thin film, and a second planar electrode; The acoustic wave device according to any one of claims 1 to 5.

20. the second substrate comprises silicon; The acoustic wave device according to claim 19 .

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