Acoustic wave device, filter and multiplexer

Abstract

To provide an acoustic wave device suppressing an area, where an acoustic wave element can be formed, from becoming smaller.SOLUTION: An acoustic wave device 100 includes: a support substrate 10; a piezoelectric layer 11 provided on the support substrate 10; an acoustic wave element 20 provided on the piezoelectric layer 11; a frame body 30 provided, on the support substrate 10, to surround the acoustic wave element 20 as viewed from the top of the piezoelectric layer 11; a lid 40 provided on the frame body 30 while sandwiching a gap 15 together with the support substrate 10, and sealing the acoustic wave element 20 in the gap 15; and a columnar body 50 which is provided between a lower surface 41 of the lid 40 and an upper surface 17 of the piezoelectric layer 11 within the gap 15 and in which a space 16 that is a gap between the lower surface 41 of the lid 40 and the columnar body is formed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to acoustic wave devices, filters, and multiplexers. [Background technology]

[0002] An acoustic wave device is known in which an acoustic wave element is provided on a substrate, a lid or another substrate is placed on the acoustic wave element, and the substrate and the lid or another substrate are connected using a metal layer to seal the acoustic wave element in a gap. It is also known to provide a columnar body in the gap between the substrate and the lid or another substrate (for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-52359 [Patent Document 2] Japanese Patent Publication No. 2023-4705 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, in order to reduce the deflection of the lid, a columnar body is provided between the lid and a support substrate exposed by a through-hole provided in the piezoelectric layer, or between the lid and a recess provided in the piezoelectric layer. In this case, the area in which the acoustic wave element can be formed is reduced in order to secure an area for forming the through-hole or recess in the piezoelectric layer.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to prevent the area in which an acoustic wave element can be formed from becoming smaller. [Means for solving the problem]

[0006] The present invention is an acoustic wave device comprising: a support substrate; a piezoelectric layer provided on the support substrate; an acoustic wave element provided on the piezoelectric layer; a frame body provided on the support substrate surrounding the acoustic wave element when viewed from above the piezoelectric layer; a lid provided on the frame body with a gap sandwiched between the support substrate and the lid, sealing the acoustic wave element within the gap; and a pillar-shaped body provided within the gap between a first surface of the lid facing the piezoelectric layer and a second surface of the piezoelectric layer facing the lid, with a gap formed between the first surface and the second surface.

[0007] In the above configuration, the columnar body may be configured to have insulating properties.

[0008] In the above configuration, the pillars may be made of resin.

[0009] In the above configuration, the height of the gap may be smaller than the height of the columnar body.

[0010] In the above configuration, the elastic wave element has a plurality of electrode fingers provided on the second surface of the piezoelectric layer, and the pillar is provided on the piezoelectric layer with the gap between it and the first surface of the lid, and can be configured to be positioned adjacent to the elastic wave element in the propagation direction of the elastic wave excited by the elastic wave element.

[0011] In the above configuration, the piezoelectric layer may be provided with a metal layer on the second surface thereof, and a plurality of the pillars may be provided, and at least some of the plurality of pillars may be provided between the first surface of the lid and a third surface of the metal layer on the lid side.

[0012] In the above configuration, the metal layer may be formed containing a material having a smaller Young's modulus than the piezoelectric layer.

[0013] In the above configuration, some of the multiple pillars have one end in contact with the second surface of the piezoelectric layer, and the remaining pillars have one end in contact with the third surface of the metal film, and the height of the gap between the other ends of some of the pillars and the first surface of the lid is larger than the height of the gap between the other ends of the remaining pillars and the first surface of the lid.

[0014] The present invention is a filter including the acoustic wave device described above.

[0015] The present invention is a multiplexer including the filter described above. [Effects of the Invention]

[0016] According to the present invention, it is possible to prevent the area in which an acoustic wave element can be formed from becoming smaller. [Brief explanation of the drawings]

[0017] [Figure 1] 1(a) and 1(b) are a cross-sectional view and a plan view of an acoustic wave device in accordance with a first embodiment, and FIG. 1(c) is an enlarged plan view of the vicinity of an acoustic wave element. [Figure 2] FIG. 2(a) is a plan view of the acoustic wave element in Example 1 when it is a surface acoustic wave resonator, and FIG. 2(b) is a cross-sectional view of the acoustic wave element when it is a film bulk acoustic resonator. [Figure 3] 3A to 3D are cross-sectional views illustrating a method for manufacturing the acoustic wave device in accordance with the first embodiment. [Figure 4] FIG. 4 is a cross-sectional view of an acoustic wave device in accordance with a first modification of the first embodiment. [Figure 5] 5(a) to 5(d) are cross-sectional views illustrating a method for manufacturing an acoustic wave device according to a modification of the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view of an acoustic wave device according to a comparative example. [Figure 7] FIG. 7A is a plan view of an acoustic wave device in accordance with a second embodiment, and FIG. 7B is a cross-sectional view taken along line AA of FIG. 7A. [Figure 8] FIG. 8(a) is a plan view of an acoustic wave device according to a modification of the second embodiment, and FIG. 8(b) is a cross-sectional view taken along the line AA in FIG. 8(a). [Figure 9] FIG. 9 is a cross-sectional view of an acoustic wave device in accordance with a third embodiment. [Figure 10] FIG. 10(a) is a circuit diagram of a filter according to the fourth embodiment, and FIG. 10(b) is a circuit diagram of a duplexer according to a modified example of the fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION [Example]

[0018] 1(a) is a cross-sectional view of an acoustic wave device 100 according to a first embodiment, FIG. 1(b) is a plan view of the acoustic wave device 100 according to the first embodiment, and FIG. 1(c) is an enlarged plan view of the vicinity of an acoustic wave element 20. FIG. 1(b) illustrates a piezoelectric layer 11, a frame body 30, and a columnar body 50 provided on a support substrate 10. The X and Y directions are perpendicular to each other in the planar direction of the support substrate 10. The Z direction is the thickness direction of the support substrate 10.

[0019] As shown in FIG. 1(a), a piezoelectric layer 11 is provided on a support substrate 10. The thickness of the piezoelectric layer 11 is, for example, 0.5 μm to 30 μm, which is smaller than the wavelength of the main mode acoustic wave (for example, surface acoustic wave) excited by the acoustic wave element 20. An insulating film such as silicon oxide and / or aluminum oxide may be provided between the support substrate 10 and the piezoelectric layer 11. An acoustic wave element 20 is provided on an upper surface 17 of the piezoelectric layer 11. The acoustic wave element 20 is, for example, a surface acoustic wave resonator, but may also be a piezoelectric thin film resonator.

[0020] 2A is a plan view of the acoustic wave element 20 of the first embodiment, which is a surface acoustic wave resonator. As shown in FIG. 2A, the acoustic wave element 20 is an IDT (Interdigital Transistor). The IDT 21 includes a pair of opposing comb electrodes 23. The comb electrodes 23 include a plurality of electrode fingers 24 and a bus bar 25 to which the plurality of electrode fingers 24 are connected. The region where the electrode fingers 24 of the pair of comb electrodes 23 intersect is an intersection region 26. The pair of comb electrodes 23 have the electrode fingers 24 alternately arranged in at least a portion of the intersection region 26. An acoustic wave excited primarily by the plurality of electrode fingers 24 in the intersection region 26 propagates primarily in the X direction. The pitch of the electrode fingers 24 of one of the pair of comb electrodes 23 (the pitch between the centers of the electrode fingers 24) is approximately the wavelength λ of the acoustic wave. If the pitch of the plurality of electrode fingers 24 is D, the pitch of the electrode fingers 24 of one of the comb electrodes 23 is D, which is the pitch of two of the electrode fingers 24. The reflector 22 reflects the acoustic waves (surface acoustic waves) excited by the electrode fingers 24. This confines the acoustic waves within the intersection region 26 of the IDT 21. The piezoelectric layer 11 is, for example, a single-crystal lithium tantalate layer, a single-crystal lithium niobate layer, or a single-crystal quartz crystal layer. The piezoelectric layer 11 may also be a rotated Y-cut X-propagation lithium tantalate layer or a rotated Y-cut X-propagation lithium niobate layer. The IDT 21 and the reflector 22 are formed of a metal film such as aluminum, copper, or molybdenum. An insulating film may be provided to cover the electrode fingers 24. The insulating film functions as a protective film or a temperature compensation film. The comb electrode 23 may have dummy electrode fingers.

[0021] FIG. 2(b) is a cross-sectional view of the acoustic wave element 20 of the first embodiment, which is a piezoelectric thin film resonator. As shown in FIG. 2(b), a piezoelectric layer 11 is provided on a support substrate 10, and a lower electrode 33 and an upper electrode 34 are provided on either side of the piezoelectric layer 11. A gap 35 is formed between the lower electrode 33 and the support substrate 10. A region where the lower electrode 33 and the upper electrode 34 face each other, sandwiching at least a portion of the piezoelectric layer 11, is a resonance region 36. In the resonance region 36, the lower electrode 33 and the upper electrode 34 excite an acoustic wave in the piezoelectric layer 11. The lower electrode 33 and the upper electrode 34 are metal films, such as a ruthenium film. The piezoelectric layer 11 is, for example, an aluminum nitride layer, a zinc oxide layer, a single-crystal lithium tantalate layer, or a single-crystal lithium niobate layer. An acoustic reflection film that reflects acoustic waves may be provided instead of the gap 35.

[0022] As shown in FIGS. 1(a) and 1(b), the piezoelectric layer 11 is not provided in the peripheral region of the support substrate 10. A frame body 30 is provided in the peripheral region of the support substrate 10 so as to surround the piezoelectric layer 11 and the acoustic wave element 20 in a plan view seen from the +Z direction. The frame body 30 includes a metal layer 31 and a bonding layer 32. A lid 40 is provided on the frame body 30, sandwiching a gap 15 between the frame body 30 and the support substrate 10. The lid 40 is bonded to the frame body 30 by the bonding layer 32. The acoustic wave element 20 is sealed within the gap 15 by the lid 40 and the frame body 30.

[0023] Terminals 13 are provided on the lower surface of support substrate 10. Via wiring 12 is provided to penetrate support substrate 10. Wiring layer 14 is provided from the upper surface of support substrate 10 to upper surface 17 of piezoelectric layer 11. Acoustic wave element 20 is connected to terminals 13 via wiring layer 14 and via wiring 12.

[0024] The support substrate 10 is a substrate made of, for example, sapphire, alumina, spinel, quartz, crystal, silicon carbide, or silicon. The via wiring 12, terminals 13, and wiring layer 14 are each a single metal layer, such as a copper layer, a gold layer, a silver layer, a titanium layer, a nickel layer, or a tungsten layer, or a laminate thereof. The frame 30 is a single metal layer, such as a copper layer, a gold layer, or a nickel layer, or a laminate thereof. The lid 40 includes a metal layer, such as an iron alloy such as Kovar or 42 alloy, an aluminum alloy such as duralumin, nickel, copper, cupronickel, or nickel silver. These metal layers of the lid 40 are exposed to the void 15. The lid 40 may also include an insulating layer, such as sapphire, alumina, spinel, or silicon. These insulating layers are provided on the opposite side of the metal layer from the void 15.

[0025] The wiring layer 14 is formed, for example, containing a material having a smaller Young's modulus than the piezoelectric layer 11. For example, if the piezoelectric layer 11 is a lithium tantalate layer (Young's modulus: 230 GPa), the wiring layer 14 is formed of a copper layer (Young's modulus: 130 GPa), a gold layer (Young's modulus: 78 GPa), a silver layer (Young's modulus: 82.7 GPa), a titanium layer (Young's modulus: 106 GPa), and a nickel layer (Young's modulus: 220 GPa). For example, if the piezoelectric layer 11 is a lithium niobate layer (Young's modulus: 170 GPa), the wiring layer 14 is formed of a copper layer (Young's modulus: 130 GPa), a gold layer (Young's modulus: 78 GPa), a silver layer (Young's modulus: 82.7 GPa), and a titanium layer (Young's modulus: 106 GPa). The wiring layer 14 may include a layer made of a material having a larger Young's modulus than the piezoelectric layer 11 in part, but it is preferable that the layer made of a material having a smaller Young's modulus than the piezoelectric layer 11 occupies 50% or more of the thickness of the wiring layer 14, more preferably 70% or more, and even more preferably 90% or more.

[0026] Within the gap 15, pillars 50 are provided between the upper surface 17 of the piezoelectric layer 11 and the lower surface 41 of the lid 40. The pillars 50 are in contact with the upper surface 17 of the piezoelectric layer 11, and define a gap 16 between the pillars 50 and the lower surface 41 of the lid 40. The height H of the gap 16 is, for example, 5 μm or more and 10 μm or less. The height of the pillars 50 is greater than the height H of the gap 16, for example, 20 μm or more and 30 μm or less. The pillars 50 have, for example, insulating properties. The pillars 50 are formed from, for example, a resin or an inorganic insulator. Examples of resins that form the pillars 50 include polyimide and epoxy. Examples of inorganic insulators that form the pillars 50 include silicon oxide and aluminum oxide.

[0027] 1(c), pillar 50 is provided adjacent to acoustic wave element 20 in the X direction. For example, when two acoustic wave elements 20 are arranged side by side in the X direction, pillar 50 is provided between the two acoustic wave elements 20.

[0028] [Manufacturing method] 3A to 3D are cross-sectional views illustrating a manufacturing method of the acoustic wave device 100 according to the first embodiment. As shown in FIG. 3A, vias are formed in the upper surface of the support substrate 10 by, for example, irradiating the upper surface with laser light, and a metal layer such as copper is formed in the vias by, for example, plating. The metal layer is then planarized using a chemical mechanical polishing (CMP) method so that the upper surface of the support substrate 10 is exposed, and via wiring 12 is formed in the support substrate 10. Next, a piezoelectric substrate is bonded to the upper surface of the support substrate 10 at room temperature using, for example, a surface activation method. The support substrate 10 and the piezoelectric substrate may be directly bonded via an amorphous layer of several nanometers or indirectly bonded via an insulating layer. The piezoelectric substrate is then polished using, for example, a CMP method, to form a piezoelectric layer 11 bonded directly or indirectly to the upper surface of the support substrate 10. Next, an acoustic wave element 20 is formed on the upper surface 17 of the piezoelectric layer 11.

[0029] 3(b), a portion of piezoelectric layer 11 is removed by, for example, etching. As a result, piezoelectric layer 11 in the peripheral region of support substrate 10 is removed and via wiring 12 is exposed. Wiring layer 14 is formed to connect acoustic wave element 20 and via wiring 12. Next, insulating film 52, such as a resin film or an inorganic insulating film, is formed on support substrate 10 to cover piezoelectric layer 11 and acoustic wave element 20.

[0030] As shown in FIG. 3( c ), the insulating film 52 is patterned using photolithography and etching to form pillars 50 on the upper surface 17 of the piezoelectric layer 11 .

[0031] 3(d), a frame 30 that surrounds the piezoelectric layer 11 and the acoustic wave element 20 is formed on the upper surface of the support substrate 10, for example, by electrolytic plating. The frame 30 includes a metal layer 31 and a bonding layer 32 provided thereon. The frame 30 is formed so that the upper surface of the frame 30 is located farther from the upper surface of the support substrate 10 than the upper surfaces of the pillars 50.

[0032] 1(a), the lid 40 is bonded to the frame 30. As a result, the acoustic wave element 20 is sealed in the cavity 15 by the frame 30 and the lid 40. A gap 16 is formed between the columnar body 50 and the lower surface 41 of the lid 40. Next, the lower surface of the support substrate 10 is polished using, for example, a CMP method to expose the via wiring 12 from the lower surface of the support substrate 10. Terminals 13 connected to the via wiring 12 are formed on the lower surface of the support substrate 10.

[0033] [Variations] 4 is a cross-sectional view of an acoustic wave device 110 according to a first modification of the first embodiment. In the first modification of the first embodiment, one end of the columnar body 50 contacts the lower surface 41 of the lid 40, and a gap 16 made of an air gap is formed between the other end and the upper surface 17 of the piezoelectric layer 11. The other configuration is the same as that of the first embodiment, and therefore a description thereof will be omitted.

[0034] [Manufacturing method] 5(a) to 5(d) are cross-sectional views showing a method for manufacturing an acoustic wave device 110 according to a modified example of Example 1. As shown in Fig. 5(a), first, the same process as that shown in Fig. 3(a) of Example 1 is carried out.

[0035] 5(b), a portion of piezoelectric layer 11 is removed by, for example, etching. This removes piezoelectric layer 11 from the peripheral region of support substrate 10 and exposes via wiring 12. Wiring layer 14 is formed to connect acoustic wave element 20 to via wiring 12. Next, frame 30 is formed on the upper surface of support substrate 10 by, for example, electrolytic plating, to surround piezoelectric layer 11 and acoustic wave element 20.

[0036] As shown in FIG. 5(c), an insulating film 52 such as a resin film or an inorganic insulating film is formed on the lid 40.

[0037] As shown in Fig. 5(d), the insulating film 52 is patterned using photolithography and etching. As a result, pillars 50 are formed on the lower surface 41 of the lid 40 (the upper surface in Fig. 5(d)). The pillars 50 are formed to a height that does not allow them to come into contact with the upper surface 17 of the piezoelectric layer 11 when the lid 40 is bonded to the frame body 30.

[0038] 4, the lid 40 is bonded to the frame 30. As a result, the acoustic wave element 20 is sealed in the cavity 15 by the frame 30 and the lid 40. A gap 16 is formed between the columnar body 50 and the upper surface 17 of the piezoelectric layer 11. Next, the lower surface of the support substrate 10 is polished using, for example, a CMP method to expose the via wiring 12 from the lower surface of the support substrate 10. Terminals 13 connected to the via wiring 12 are formed on the lower surface of the support substrate 10.

[0039] [Comparative Example] FIG. 6 is a cross-sectional view of an acoustic wave device 500 according to a comparative example. As shown in FIG. 6, in the comparative example, the piezoelectric layer 11 has a through-hole 18 penetrating from the upper surface 17 to the lower surface. The surface of the support substrate 10 is exposed in the through-hole 18. A pillar 60 is provided between the support substrate 10 and the lid 40 in the through-hole 18. The pillar 60 includes a metal layer 61 and a bonding layer 62. The lid 40 is bonded to the pillar 60 by the bonding layer 62. The metal layer 61 is formed simultaneously with the metal layer 31 of the frame body 30, and therefore is made of the same metal material and has the same thickness as the metal layer 31. The bonding layer 62 is formed simultaneously with the bonding layer 32 of the frame body 30, and therefore is made of the same metal material and has the same thickness as the bonding layer 32. The other configurations are the same as those in Example 1, and therefore will not be described again.

[0040] In the comparative example, pillars 60 are provided between the support substrate 10 and the lid 40. Therefore, even if external pressure is applied to the lid 40, the pillars 60 prevent the lid 40 from bending. This prevents the lid 40 from approaching or contacting the acoustic wave element 20, thereby suppressing deterioration of its characteristics. Furthermore, because the pillars 60 are provided in the through holes 18 of the piezoelectric layer 11, even if the lid 40 vibrates, the vibrations are prevented from being transmitted from the pillars 60 to the piezoelectric layer 11, minimizing the impact on the acoustic wave element 20. However, in order to fit the pillars 60 into the through holes 18, the width W of the through holes 18 must be set sufficiently larger than the pillars 60, taking into account manufacturing errors and the like. This reduces the area in which the acoustic wave element 20 can be formed. In particular, if the side surfaces of the piezoelectric layer 11 are tapered to prevent disconnection of the wiring layer 14, the area in which the acoustic wave element 20 can be formed becomes even smaller.

[0041] On the other hand, according to Example 1 and its modifications, as shown in FIGS. 1( a) and 4, the pillars 50 are provided between the lower surface 41 (first surface) of the lid 40 and the upper surface 17 (second surface) of the piezoelectric layer 11. As a result, even if pressure is applied to the lid 40 from the outside, the pillars 50 can prevent the lid 40 from bending. Furthermore, since no through-holes for the pillars 50 are provided in the piezoelectric layer 11, a reduction in the area in which the acoustic wave element 20 can be formed can be prevented. Furthermore, a gap 16, which is an air gap, is formed between the pillars 50 and either the lower surface 41 of the lid 40 or the upper surface 17 of the piezoelectric layer 11. As a result, even if the lid 40 vibrates, the gap 16 prevents the vibration from being transmitted to the piezoelectric layer 11, thereby minimizing the effect on the acoustic wave element 20.

[0042] Furthermore, in Example 1 and its modified examples, the pillars 50 have insulating properties, which allows the positions of the pillars 50 on the piezoelectric layer 11 to be freely selected, and the pillars 50 can be disposed at positions where the deflection of the lid 40 can be effectively suppressed.

[0043] Furthermore, in Example 1 and its modifications, the pillars 50 are made of resin. Since resin is a relatively soft material (Young's modulus of polyimide: 3 to 5 GPa, Young's modulus of epoxy: 2.6 to 3 GPa, Young's modulus of polyurethane: 7 to 70 GPa), even if the lid 40 bends significantly and presses against the pillars 50, the pressing force is weakened by the pillars 50, and the force transmitted to the piezoelectric layer 11 can be reduced. This makes it possible to prevent cracks from occurring in the piezoelectric layer 11 and to prevent adverse effects on the acoustic wave element 20.

[0044] Furthermore, in Example 1 and its modified examples, the height H of the gap 16 is smaller than the height of the pillars 50. This makes it possible to suppress deflection of the lid 40. From the viewpoint of suppressing deflection of the lid 40, the height H of the gap 16 is preferably ½ or less, more preferably ⅓ or less, and even more preferably ¼ or less of the height of the pillars 50.

[0045] 1(a) and 1(c), in Example 1, columns 50 are provided on piezoelectric layer 11 with gap 16 between them and lower surface 41 of lid 40, and are disposed adjacent to acoustic wave element 20 in the propagation direction (X direction) of the acoustic waves excited by acoustic wave element 20. This allows columns 50 to suppress leakage of acoustic wave vibration. From the viewpoint of not interfering with the excitation of acoustic waves by acoustic wave element 20, distance L between acoustic wave element 20 and columns 50 is preferably 5 μm or more, and more preferably 6 μm or more. From the viewpoint of suppressing leakage of acoustic wave vibration, distance L is preferably 10 μm or less, and more preferably 9 μm or less. [Example]

[0046] FIG. 7(a) is a plan view of an acoustic wave device 200 according to a second embodiment, and FIG. 7(b) is a cross-sectional view taken along line AA of FIG. 7(a). As shown in FIGS. 7(a) and 7(b), in the second embodiment, one or more series resonators S1 to S4 and one or more parallel resonators P1 to P3 are provided on a piezoelectric layer 11. The series resonators S1 to S4 and the parallel resonators P1 to P3 constitute an acoustic wave element 20. Terminals 13 provided on the lower surface of a support substrate 10 include an input terminal Tin, an output terminal Tout, and a ground terminal Tg. The series resonators S1 to S4 are connected in series between the input terminal Tin and the output terminal Tout via via wiring 12 and a wiring layer 14. One end of each of the parallel resonators P1 to P3 is connected between the series resonators S1 to S4 via the wiring layer 14, and the other end is connected to the ground terminal Tg via the wiring layer 14 and the via wiring 12.

[0047] A plurality of pillars 50 are provided on the piezoelectric layer 11. Some of the pillars 50 have one end in contact with the upper surface 17 of the piezoelectric layer 11, and a gap 16 made of an air gap is formed between the other end and the lower surface 41 of the lid 40. The remaining pillars 50 have one end in contact with the upper surface 19 of the wiring layer 14, and a gap 16 made of an air gap is formed between the other end and the lower surface 41 of the lid 40. The rest of the configuration is the same as in Example 1, so a description thereof will be omitted.

[0048] [Variations] Fig. 8(a) is a plan view of an acoustic wave device 210 according to a modification of Example 2, and Fig. 8(b) is a cross-sectional view taken along line AA in Fig. 8(a). As shown in Fig. 8(a) and Fig. 8(b), in the modification of Example 2, one end of each of the plurality of pillars 50 contacts the upper surface 19 of the wiring layer 14, and a gap 16 made of an air gap is formed between the other end and the lower surface 41 of the lid 40. The other configuration is the same as in Example 2, and therefore description thereof will be omitted.

[0049] According to Example 2 and its modified example, at least some of the multiple pillars 50 are provided between the lower surface 41 (first surface) of the lid 40 and the upper surface 19 (third surface) of the wiring layer 14 (metal layer). As a result of the wiring layer 14 being provided below the pillars 50, when the pillars 50 are pressed by the lid 40, the pressing force is transmitted to the piezoelectric layer 11 via the wiring layer 14, thereby reducing the pressing force transmitted to the piezoelectric layer 11. This makes it possible to prevent cracks from occurring in the piezoelectric layer 11 and to prevent adverse effects on the acoustic wave element 20.

[0050] Furthermore, in Example 2 and its modified examples, the wiring layer 14 is formed containing a material having a smaller Young's modulus than the piezoelectric layer 11. This makes it possible to further reduce the force transmitted to the piezoelectric layer 11 when the pillars 50 are pressed by the lid 40.

[0051] 7(a) and 7(b), some of the multiple columns 50 are provided with one end in contact with the upper surface 17 of the piezoelectric layer 11, and the remaining columns 50 are provided with one end in contact with the upper surface 19 of the wiring layer 14. The height h1 of the gap 16 between the other end of the columns 50 in contact with the upper surface 17 of the piezoelectric layer 11 and the lower surface 41 of the lid 40 is larger than the height h2 of the gap 16 between the other end of the columns 50 in contact with the upper surface 19 of the wiring layer 14 and the lower surface 41 of the lid 40. As a result, when the lid 40 bends, the lid 40 is likely to first come into contact with the columns 50 provided in contact with the upper surface 19 of the wiring layer 14, and therefore, even when the columns 50 are pressed by the lid 40, the force transmitted to the piezoelectric layer 11 can be reduced.

[0052] 8(a) and 8(b), all of the pillars 50 are provided between the lower surface 41 of the lid 40 and the upper surface 19 of the wiring layer 14. This makes it possible to further reduce the force transmitted to the piezoelectric layer 11 when the pillars 50 are pressed by the lid 40.

[0053] In Example 2 and its modified example, the pillars 50 are in contact with the upper surface 17 of the piezoelectric layer 11 or the upper surface 19 of the wiring layer 14, and a gap 16 is formed between the pillars 50 and the lower surface 41 of the lid 40, but this is not the only example. The pillars 50 may be in contact with the lower surface 41 of the lid 40, and a gap 16 may be formed between the pillars 50 and the upper surface 17 of the piezoelectric layer 11 or the upper surface 19 of the wiring layer 14, as in the modified example of Example 1. [Example]

[0054] 9 is a cross-sectional view of an acoustic wave device 300 according to Example 3. As shown in Fig. 9, Example 3 includes a columnar body 50 in contact with the upper surface 17 of the piezoelectric layer 11 and having a gap 16 formed between it and the lower surface 41 of the lid 40, as well as a columnar body 50a in contact with both the upper surface 19 of the wiring layer 14 and the lower surface 41 of the lid 40. The other configurations are the same as those of Example 2, and therefore will not be described again.

[0055] As in the third embodiment, the pillars 50a may be provided in contact with both the upper surface 19 of the wiring layer 14 and the lower surface 41 of the lid 40. [Example]

[0056] FIG. 10(a) is a circuit diagram of a filter 400 according to a fourth embodiment. As shown in FIG. 10(a), one or more series resonators S11 to S14 are connected in series between an input terminal Tin and an output terminal Tout. One or more parallel resonators P11 to P13 are connected in parallel between the input terminal Tin and the output terminal Tout. The acoustic wave device according to the first embodiment and its modifications can be used for at least one of the one or more series resonators S11 to S14 and the one or more parallel resonators P11 to P13. The number of resonators in the ladder filter can be set as appropriate. The filter may be a multimode filter.

[0057] FIG. 10(b) is a circuit diagram of a duplexer 410 according to a modification of the fourth embodiment. As shown in FIG. 10(b), a transmit filter 70 is connected between a common terminal Ant and a transmit terminal Tx. A receive filter 72 is connected between the common terminal Ant and a receive terminal Rx. The transmit filter 70 passes, to the common terminal Ant, signals in the transmit band among the high-frequency signals input from the transmit terminal Tx as transmit signals, and suppresses signals of other frequencies. The receive filter 72 passes, to the receive terminal Rx, signals in the receive band among the high-frequency signals input from the common terminal Ant as receive signals, and suppresses signals of other frequencies. At least one of the transmit filter 70 and the receive filter 72 may be the filter according to the second embodiment, its modification, or the third embodiment. Although a duplexer has been described as an example of a multiplexer, a triplexer or a quadplexer may also be used.

[0058] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0059] 10...support substrate, 11...piezoelectric layer, 12...via wiring, 13...terminal, 14...wiring layer, 15...gap, 16...gap, 17...upper surface of piezoelectric layer, 18...through hole, 19...upper surface of wiring layer, 20...acoustic wave element, 21...IDT, 22...reflector, 23...comb-shaped electrode, 24...electrode finger, 25...bus bar, 26...intersection region, 30...frame, 31...metal layer, 32...bonding layer, 33...lower electrode, 34...upper electrode, 35...gap, 36...resonance region, 40...lid, 41...lower surface of lid, 50, 50a...columnar body, 52...insulating film, 60...columnar body, 61...metal layer, 62...bonding layer, 100, 110, 200, 210, 300, 500...acoustic wave device, 400...filter, 410...duplexer

Claims

1. A support substrate; a piezoelectric layer provided on the support substrate; an acoustic wave element provided on the piezoelectric layer; a frame provided on the support substrate to surround the acoustic wave element when viewed from above the piezoelectric layer; a lid provided on the frame with a gap sandwiched between the lid and the support substrate, the lid sealing the acoustic wave element in the gap; An elastic wave device comprising: a pillar-shaped body arranged within the gap between a first surface of the lid facing the piezoelectric layer and a second surface of the piezoelectric layer facing the lid, with a gap being formed between the pillar-shaped body and either the first surface or the second surface.

2. The acoustic wave device according to claim 1 , wherein the pillars have insulating properties.

3. The acoustic wave device according to claim 1 , wherein the pillars are made of resin.

4. The acoustic wave device according to claim 1 , wherein the height of the gap is smaller than the height of the columnar body.

5. the acoustic wave element has a plurality of electrode fingers provided on the second surface of the piezoelectric layer, The elastic wave device of claim 1 or 2, wherein the pillar is provided on the piezoelectric layer with the gap between it and the first surface of the lid, and is positioned adjacent to the elastic wave element in the propagation direction of the elastic wave excited by the elastic wave element.

6. a metal layer provided on the second surface of the piezoelectric layer; A plurality of the pillars are provided, The acoustic wave device according to claim 1 , wherein at least some of the plurality of columns are provided between the first surface of the lid and a third surface of the metal layer on the lid side.

7. The acoustic wave device according to claim 6 , wherein the metal layer is formed of a material having a Young's modulus smaller than that of the piezoelectric layer.

8. some of the plurality of columns have one ends in contact with the second surface of the piezoelectric layer, and the remaining columns have one ends in contact with the third surface of the metal layer; The acoustic wave device of claim 6, wherein the height of the gap between the other ends of the some of the columns and the first surface of the lid is greater than the height of the gap between the other ends of the remaining columns and the first surface of the lid.

9. A filter comprising the acoustic wave device according to claim 1 or 2.

10. A multiplexer including the filter of claim 9.

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