Acoustic wave device, filter, multiplexer, and method for manufacturing an acoustic wave device

Abstract

To provide an acoustic wave device which inhibits disconnection of a wiring.SOLUTION: An acoustic wave device 100 includes: a support substrate 10; a via wiring 26 which penetrates through the support substrate 10 and protrudes from an upper surface 11 of the support substrate 10; a piezoelectric layer 14 which is provided on the support substrate 10 and does not overlap with the via wiring 26 in a plan view; an insulation layer 12 which is provided between the support substrate 10 and the piezoelectric layer 14 and does not overlap with the via wiring 26 in the plan view; an acoustic wave element 30 provided on the piezoelectric layer 14; and a wiring 40 which is provided on an area ranging from the via wiring 26 to the piezoelectric layer 14 and electrically connects the via wiring 26 with the acoustic wave element 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an acoustic wave device, a filter, a multiplexer, and a method for manufacturing an acoustic wave device. [Background technology]

[0002] BACKGROUND ART A structure in which a piezoelectric layer is provided on a support substrate is known as an acoustic wave device used in communication devices such as smartphones (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-022501 Summary of the Invention [Problem to be solved by the invention]

[0004] In a structure in which a piezoelectric layer is provided on a support substrate via an insulating layer, a wiring is provided from above the via wiring to above the piezoelectric layer in order to electrically connect a via wiring penetrating the support substrate to an acoustic wave element provided on the piezoelectric layer. In this case, a break may occur when the wiring is drawn out from above the via wiring.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to suppress disconnection of wiring. [Means for solving the problem]

[0006] The present invention is an elastic wave device comprising a support substrate, via wiring penetrating the support substrate and protruding from the upper surface of the support substrate, a piezoelectric layer provided on the support substrate and not overlapping the via wiring in a planar view, an insulating layer provided between the support substrate and the piezoelectric layer and not overlapping the via wiring in a planar view, an elastic wave element provided on the piezoelectric layer, and wiring provided from above the via wiring to above the piezoelectric layer, electrically connecting the via wiring and the elastic wave element.

[0007] In the above configuration, the via wiring may have a flat upper surface and an inclined surface located around the upper surface and inclined obliquely upward toward the upper surface.

[0008] In the above configuration, the upper surface of the support substrate that is not covered with the insulating layer in a plan view may be recessed with respect to the upper surface of the support substrate that is covered with the insulating layer.

[0009] In the above configuration, the maximum thickness of the upper surface of the via wiring protruding from the upper surface of the support substrate may be 2.5 times or less the thickness of the wiring.

[0010] In the above configuration, the piezoelectric layer may be a lithium tantalate layer or a lithium niobate layer.

[0011] In the above configuration, the support substrate may be a sapphire substrate, an alumina substrate, a spinel substrate, a quartz substrate, a crystal substrate, or a silicon substrate, and the via wiring may be composed primarily of copper, silver, or gold.

[0012] In the above configuration, the configuration can include a ring-shaped body provided on the support substrate surrounding the elastic wave element in a planar view, a lid body provided on the ring-shaped body with a gap between it and the support substrate and sealing the elastic wave element within the gap, and a pillar-shaped body provided between the via wiring and the lid body in the gap, covering an upper surface of the via wiring in a planar view, and having a lower surface located around the via wiring that is closer to the support substrate than the upper surface of the wiring on the via wiring.

[0013] The present invention is a filter including the acoustic wave device described above.

[0014] The present invention is a multiplexer including the filter described above.

[0015] The present invention is a method for manufacturing an acoustic wave device, comprising the steps of: forming a via wiring in a support substrate; forming an insulating layer on the support substrate after forming the via wiring; forming a piezoelectric layer on the insulating layer; forming an acoustic wave element on the piezoelectric layer; removing the piezoelectric layer and the insulating layer in an area that overlaps with the via wiring in a planar view and in an area surrounding the via wiring, and causing the via wiring to protrude from the top surface of the support substrate; and, after causing the via wiring to protrude from the top surface of the support substrate, forming wiring that extends from above the via wiring to above the piezoelectric layer and electrically connects the via wiring to the acoustic wave element. [Effects of the Invention]

[0016] According to the present invention, disconnection of wiring can be suppressed. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1(a) is a cross-sectional view of an acoustic wave device in accordance with a first embodiment, and FIG. 1(b) is an enlarged view of a region A in FIG. 1(a). [Figure 2] FIG. 2 is a plan view of a portion of the acoustic wave device in accordance with the first embodiment. [Figure 3]FIG. 3 is a plan view of the acoustic wave device according to the first embodiment. [Figure 4] 4(a) to 4(c) are cross-sectional views (part 1) illustrating a method for manufacturing the acoustic wave device in accordance with the first embodiment. [Figure 5] 5(a) to 5(c) are cross-sectional views (part 2) illustrating a method for manufacturing the acoustic wave device in accordance with the first embodiment. [Figure 6] FIG. 6(a) is a cross-sectional view of an acoustic wave device according to a comparative example, and FIG. 6(b) is an enlarged view of region A in FIG. 6(a). [Figure 7] 7A to 7C are cross-sectional views illustrating a method for manufacturing an acoustic wave device according to a comparative example. [Figure 8] FIG. 8 is a cross-sectional view illustrating a problem that occurs in an acoustic wave device according to a comparative example. [Figure 9] FIG. 9 is a cross-sectional view of an acoustic wave device in accordance with a second embodiment. [Figure 10] 10A is a plan view of an acoustic wave device in accordance with Example 2, and FIG. 10B is an enlarged cross-sectional view of the vicinity of a columnar body in FIG. [Figure 11] FIG. 11 is a circuit diagram of a filter according to a third embodiment. [Figure 12] FIG. 12 is a circuit diagram of a duplexer according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. [Example]

[0019] FIG. 1(a) is a cross-sectional view of an acoustic wave device 100 according to a first embodiment, and FIG. 1(b) is an enlarged view of region A in FIG. 1(a). As shown in FIG. 1(a), a piezoelectric layer 14 is provided on a support substrate 10. An insulating layer 12 is provided between the support substrate 10 and the piezoelectric layer 14. The insulating layer 12 includes a boundary layer 16 provided on the support substrate 10 and a temperature compensating layer 18 provided on the boundary layer 16. A metal film 20 is provided on the piezoelectric layer 14. The metal film 20 forms an acoustic wave element 30. A protective film 22 is provided to cover the acoustic wave element 30. A via wiring 26 is provided through the support substrate 10. The via wiring 26 is embedded in a hole 28 that penetrates the support substrate 10. A terminal 24 is provided on the lower surface of the support substrate 10 and is electrically connected to the via wiring 26.

[0020] In region 29, the piezoelectric layer 14 and the insulating layer 12 have been removed. Region 29 overlaps with via wiring 26 in a planar view. The upper surface 11 of the support substrate 10 not covered with insulating layer 12 is recessed relative to the upper surface 11 of the support substrate 10 covered with insulating layer 12. The recess amount D of the upper surface 11 of the support substrate 10 not covered with insulating layer 12 relative to the upper surface 11 of the support substrate 10 covered with insulating layer 12 is, for example, approximately 0.5 μm to 5 μm. The upper surface 11 of the support substrate 10 may be an uneven surface both in the portion covered with insulating layer 12 and in the portion not covered with insulating layer 12. When the upper surface 11 of the support substrate 10 is an uneven surface, recess amount D is calculated, for example, by a plane passing through the midpoint between the highest and lowest points of the unevenness. Wiring 40 is provided from above via wiring 26 in region 29, across the side surfaces of insulating layer 12 and piezoelectric layer 14, and onto piezoelectric layer 14. Wiring 40 includes an adhesive layer 42 and a low-resistance layer 44 provided on adhesive layer 42 and having a lower electrical resistivity than adhesive layer 42. Wiring 40 electrically connects acoustic wave element 30 and via wiring 26. The electrical connection may be such that there is conduction in either DC or AC.

[0021] 1(b), in region 29, upper surface 25 of via wiring 26 protrudes from upper surface 11 of support substrate 10. Via wiring 26 has, as a surface protruding from upper surface 11 of support substrate 10, a substantially flat upper surface 25 and inclined surfaces 27 positioned around upper surface 25 and inclined so as to rise toward upper surface 25. The inclination angle θ of inclined surfaces 27 is, for example, approximately 5° to 45°. Wiring 40 is formed along upper surface 25 and inclined surfaces 27 of via wiring 26.

[0022] The maximum thickness H of the upper surface 25 of the via wiring 26 protruding from the upper surface 11 of the support substrate 10 is, for example, 0.5 μm to 5 μm. If the upper surface 11 of the support substrate 10 is an uneven surface, the maximum thickness H is calculated, for example, from a plane passing through the midpoint between the highest and lowest points of the unevenness. The thickness of the adhesion layer 42 of the wiring 40 is, for example, approximately 100 nm to 300 nm, and the thickness of the low-resistance layer 44 is, for example, approximately 800 nm to 1200 nm. The thickness T of the wiring 40 is, for example, approximately 1000 nm to 1500 nm. The maximum thickness H of the upper surface 25 of the via wiring 26 protruding from the upper surface 11 of the support substrate 10 is, for example, 2.5 times or less the thickness T of the wiring 40. A metal layer such as a titanium layer may be provided between the via wiring 26 and the adhesion layer 42. The thickness of the metal layer may be approximately 1000 nm. The metal layer may be provided so as to completely cover the via wiring 26 in a plan view.

[0023] The support substrate 10 is, for example, a sapphire substrate, alumina substrate, spinel substrate, quartz substrate, crystal substrate, or silicon substrate having a thickness of 50 μm to 500 μm, for example, a sapphire substrate having a thickness of 75 μm. The sapphire substrate is a substrate mainly composed of single-crystal Al2O3, the alumina substrate is a substrate mainly composed of polycrystalline Al2O3, and the spinel substrate is a substrate mainly composed of single-crystal or polycrystalline MgAl2O4. The quartz substrate is a substrate mainly composed of amorphous SiO2, the crystal substrate is a substrate mainly composed of single-crystal SiO2, and the silicon substrate is a substrate mainly composed of single-crystal or polycrystalline Si. The insulating layer 12 is, for example, about 1 μm to 40 μm thick and is a single-layer or composite inorganic insulating film such as a silicon oxide film, a silicon nitride film, or an aluminum oxide film. Boundary layer 16 is, for example, an aluminum oxide film having a thickness of 1.1 μm to 1.35 μm, and is a film with a faster acoustic velocity than temperature compensating layer 18. Temperature compensating layer 18 is, for example, a silicon oxide film having a thickness of 450 nm to 660 nm, and is, for example, a silicon oxide film containing impurities such as fluorine, or an undoped silicon oxide film. The sign of the temperature coefficient of the elastic constant of temperature compensating layer 18 is opposite to the sign of the temperature coefficient of the elastic constant of piezoelectric layer 14.

[0024] The piezoelectric layer 14 is, for example, a single-crystal lithium tantalate layer or a single-crystal lithium niobate layer, for example, a rotated Y-cut X-propagation lithium tantalate layer having a thickness of 0.75 μm to 1.1 μm. The interface between the support substrate 10 and the insulating layer 12 may be a mirror surface or a textured surface. The surface roughness Ra of the upper surface 11 of the support substrate 10 may be, for example, approximately 100 nm to 500 nm. A bonding layer that bonds the temperature compensating layer 18 and the piezoelectric layer 14 may be provided between the temperature compensating layer 18 and the piezoelectric layer 14. The bonding layer is, for example, an aluminum oxide film having a thickness of 10 nm.

[0025] The metal film 20 is, for example, an aluminum film, an aluminum alloy film, or a molybdenum film. The protective film 22 is, for example, an insulating film such as a silicon oxide film or a silicon nitride film. The adhesion layer 42 of the wiring 40 is, for example, a titanium layer or a titanium tungsten layer, for example, a titanium layer having a thickness of 200 nm. The low-resistance layer 44 is, for example, a gold layer, for example, a gold layer having a thickness of 1000 nm. The via wiring 26 is, for example, a copper layer, a silver layer, or a gold layer having a maximum diameter of approximately 20 μm to 60 μm, for example, a copper layer having a maximum diameter of 40 μm. The surface roughness Ra of the upper surface 25 of the via wiring 26 is, for example, approximately 0.1 nm to 0.5 nm. The terminal 24 is, for example, formed by stacking, from the support substrate 10 side, a copper film having a thickness of 2 μm, a nickel film having a thickness of 5 μm, and a gold film having a thickness of 0.3 μm.

[0026] FIG. 2 is a plan view of a portion of the acoustic wave device 100 in accordance with the first embodiment. FIG. 2 illustrates the vicinity of the via wiring 26. As shown in FIG. 2, the via wiring 26 is provided in the support substrate 10 in a region 29 where the piezoelectric layer 14 and the insulating layer 12 (not shown in FIG. 2) have been removed. The width of the wiring 40 is, for example, larger than that of the via wiring 26. In a plan view, the wiring 40 is provided so as to cover the via wiring 26. The wiring 40 may be provided so as to completely cover the via wiring 26, or may be provided so as not to cover a portion of the via wiring 26. In this case, the width of the wiring 40 may be smaller than that of the via wiring 26.

[0027] FIG. 3 is a plan view of an acoustic wave element 30 according to a first embodiment. As shown in FIG. 3, the acoustic wave element 30 is a surface acoustic wave resonator. An IDT (Interdigital Transducer) 32 and a reflector 34 are formed on a piezoelectric layer 14. The IDT 32 has a pair of comb electrodes 36 facing each other. The comb electrode 36 has a plurality of electrode fingers 37 and a bus bar 38 connecting the plurality of electrode fingers 37. The reflectors 34 are provided on both sides of the IDT 32. The IDT 32 excites a surface acoustic wave in the piezoelectric layer 14. The wavelength of the acoustic wave is approximately equal to the pitch of the electrode fingers 37 of one of the pair of comb electrodes 36. In other words, the wavelength of the acoustic wave is approximately equal to twice the pitch of the electrode fingers 37 of the pair of comb electrodes 36.

[0028] [Manufacturing method] 4(a) to 5(c) are cross-sectional views illustrating a manufacturing method of the acoustic wave device 100 according to the first embodiment. As shown in FIG. 4(a), a hole 28 is formed in the support substrate 10. At this stage, the hole 28 does not necessarily penetrate the support substrate 10. The hole 28 is formed, for example, by irradiating it with laser light. A metal layer is formed in the hole 28 and on the support substrate 10, for example, by plating. The metal layer on the support substrate 10 is removed, for example, by CMP (Chemical Mechanical Polishing). As a result, a via wiring 26 is formed in the hole 28.

[0029] As shown in FIG. 4(b), an insulating layer 12 including a boundary layer 16 and a temperature compensating layer 18 is formed on a support substrate 10. The insulating layer 12 is formed, for example, by CVD (Chemical Vapor Deposition). A piezoelectric substrate is bonded onto the insulating layer 12. A bonding layer for bonding the insulating layer 12 and the piezoelectric substrate may be formed on the insulating layer 12. A surface activation method, for example, is used to bond the piezoelectric substrate. The top surface of the piezoelectric substrate is polished, for example, by CMP, to form a piezoelectric layer 14 of the desired thickness.

[0030] As shown in FIG. 4(c), an acoustic wave element 30 is formed by forming a metal film 20 on the piezoelectric layer 14. The acoustic wave element 30 is formed using, for example, a vacuum deposition method and a lift-off method, or a sputtering method and an etching method. A protective film 22 is formed on the piezoelectric layer 14 so as to cover the acoustic wave element 30. The protective film 22 is formed using, for example, a CVD method.

[0031] As shown in FIG. 5A, the piezoelectric layer 14 and the insulating layer 12 are removed in a region 29 that overlaps with the via wiring 26 in a plan view and that includes the region surrounding the via wiring 26. The piezoelectric layer 14 and the insulating layer 12 are removed, for example, by dry etching. For example, if the piezoelectric layer 14 is a lithium tantalate layer or a lithium niobate layer, the piezoelectric layer 14 is removed by dry etching using an etching gas primarily containing argon gas. If the insulating layer 12 is primarily composed of silicon oxide and / or aluminum oxide, the etching gas is switched from primarily containing argon gas to primarily containing a chlorine-based gas, and the insulating layer 12 is removed by dry etching. For example, if the support substrate 10 is a sapphire substrate, after removing the insulating layer 12, dry etching is performed using an etching gas primarily containing a chlorine-based gas, thereby etching the support substrate 10 at a faster rate than the via wiring 26. This allows the upper surface 25 of the via wiring 26 to protrude from the upper surface 11 of the support substrate 10. In this way, by etching the support substrate 10 under conditions where the etching rate of the support substrate 10 is faster than the etching rate of the via wiring 26, the upper surface 25 of the via wiring 26 is made to protrude from the upper surface 11 of the support substrate 10. Note that the switching from the etching gas containing argon gas as a main component to the etching gas containing a chlorine-based gas as a main component may be performed during etching of the insulating layer 12 or at the moment when the insulating layer 12 is removed and the support substrate 10 and the via wiring 26 are exposed.

[0032] 5(b), wiring 40 is formed from above the via wiring 26, through the insulating layer 12 and the side surface of the piezoelectric layer 14, and onto the piezoelectric layer 14. For example, the wiring 40 is formed by forming an adhesion layer 42 and a seed layer (not shown) on the adhesion layer 42 using a sputtering method, and then forming a low-resistance layer 44 on the seed layer using an electrolytic plating method.

[0033] 5(c), the lower surface of the support substrate 10 is polished or ground. As a result, the via wiring 26 is exposed on the lower surface of the support substrate 10. Terminals 24 to be connected to the via wiring 26 are formed on the lower surface of the support substrate 10. In this way, the acoustic wave device in accordance with the first embodiment is formed.

[0034] [Comparative Example] Fig. 6(a) is a cross-sectional view of an acoustic wave device 500 according to a comparative example, and Fig. 6(b) is an enlarged view of region A in Fig. 6(a). As shown in Figs. 6(a) and 6(b), in the acoustic wave device 500 according to the comparative example, the via wiring 26 is recessed from the upper surface 11 of the support substrate 10. The depth D of the recess from the upper surface 11 of the support substrate 10 to the upper surface 25 of the via wiring 26 is, for example, approximately 3 µm to 10 µm. The other configurations are the same as those in Figs. 1(a) and 1(b) of the first embodiment, and therefore description thereof will be omitted.

[0035] 7(a) to 7(c) are cross-sectional views illustrating a manufacturing method of an acoustic wave device 500 according to a comparative example. First, the same processes as those described with reference to FIGS. 4(a) to 4(c) of the first embodiment are performed. Then, as shown in FIG. 7(a), the piezoelectric layer 14 and the insulating layer 12 are removed from a region 29 that overlaps with the via wiring 26 in a plan view and that includes the region surrounding the via wiring 26. The piezoelectric layer 14 and the insulating layer 12 are removed by dry etching using an etching gas primarily containing argon gas, for example. During this process, overetching is performed to prevent the insulating layer 12 from remaining. When the support substrate 10 is, for example, a sapphire substrate and the via wiring 26 is, for example, primarily copper, the etching rate of the via wiring 26 is faster than the etching rate of the support substrate 10 during dry etching using argon gas as the primary component. Therefore, the via wiring 26 is recessed relative to the upper surface 11 of the support substrate 10.

[0036] As shown in FIG. 7(b), wiring 40 is formed from above the via wiring 26 through the insulating layer 12 and the side surface of the piezoelectric layer 14 onto the piezoelectric layer 14.

[0037] 7(c), the lower surface of the support substrate 10 is polished or ground to expose the via wiring 26 on the lower surface of the support substrate 10. Terminals 24 to be connected to the via wiring 26 are formed on the lower surface of the support substrate 10. In this way, an acoustic wave device according to the comparative example is formed.

[0038] 8 is a cross-sectional view illustrating a problem that occurs in an acoustic wave device 500 according to a comparative example. As shown in FIG. 8, in the acoustic wave device 500 according to the comparative example, the via wiring 26 is recessed from the upper surface 11 of the support substrate 10. Because the via wiring 26 is recessed from the upper surface 11 of the support substrate 10 due to over-etching, the depth of the recess is not uniform and may be deep. The wiring 40 is formed by extending from the upper surface 25 of the via wiring 26 to the upper surface 11 of the support substrate 10 protruding beyond the via wiring 26. In this case, the thickness of the wiring 40 is reduced at a location where the upper surface 25 of the via wiring 26 contacts the side surface of the hole 28 in the support substrate 10, which may result in a break 50 in the wiring 40. For example, if the via wiring 26 is recessed to a large extent from the upper surface 11 of the support substrate 10, or if the upper surface 25 of the via wiring 26 has a shape in which the central region is raised compared to the peripheral region, breaks 50 are more likely to occur in the wiring 40 near the boundary between the upper surface 25 of the via wiring 26 and the hole 28 of the support substrate 10.

[0039] 1(a) and 1(b), the via wiring 26 is provided to protrude from the upper surface 11 of the support substrate 10. This prevents the wiring 40 provided from above the via wiring 26 to above the piezoelectric layer 14 from having a thin portion. This prevents the wiring 40 from being broken.

[0040] Furthermore, according to Example 1, as shown in Fig. 5(a), the piezoelectric layer 14 and the insulating layer 12 are removed from an area 29 including an area overlapping with the via wiring 26 in a plan view and an area around the via wiring 26, and the via wiring 26 is made to protrude from the upper surface 11 of the support substrate 10. Then, as shown in Fig. 5(b), a wiring 40 is formed from above the via wiring 26 to above the piezoelectric layer 14. This makes it possible to prevent the wiring 40 from becoming thin in places, and to prevent breaks in the wiring 40.

[0041] 5(a), in Example 1, the piezoelectric layer 14 and the insulating layer 12 are removed and the via wiring 26 is made to protrude from the upper surface 11 of the support substrate 10 by etching. This enables continuous processing, prevents the manufacturing process from becoming complicated, and reduces the number of manufacturing steps.

[0042] 1(b), the via wiring 26 has a substantially flat upper surface 25 and an inclined surface 27 located around the upper surface 25 and inclined obliquely upward toward the upper surface 25. This makes it possible to prevent the wiring 40 from having a thin portion, and to prevent breakage of the wiring 40. In order to prevent breakage of the wiring 40, the inclination angle θ of the inclined surface 27 is preferably 5° to 45°, more preferably 5° to 40°, and even more preferably 5° to 30°.

[0043] 1(a), the upper surface 11 of the support substrate 10 that is not covered with the piezoelectric layer 14 and the insulating layer 12 is recessed relative to the upper surface 11 of the support substrate 10 that is covered with the piezoelectric layer 14 and the insulating layer 12. This allows the via wiring 26 to protrude from the upper surface 11 of the support substrate 10, thereby preventing breaks in the wiring 40. The recess amount D of the upper surface 11 of the support substrate 10 that is not covered with the insulating layer 12 and the piezoelectric layer 14 relative to the upper surface 11 of the support substrate 10 that is covered with the insulating layer 12 and the piezoelectric layer 14 may be 0.5 μm to 5 μm, 0.5 μm to 4 μm, or 0.5 μm to 3 μm.

[0044] 1(b), the maximum thickness H of the upper surface 25 of the via wiring 26 protruding from the upper surface 11 of the support substrate 10 is 2.5 times or less the thickness T of the wiring 40. This makes it possible to prevent the wiring 40 from having thin portions, and to prevent breaks in the wiring 40. In order to prevent breaks in the wiring 40, the maximum thickness H is preferably 2 times or less the thickness T of the wiring 40, more preferably 1.5 times or less, and even more preferably 1 time or less.

[0045] In Example 1, the piezoelectric layer 14 is a lithium tantalate layer or a lithium niobate layer. In this case, the piezoelectric layer 14 is removed by dry etching using an etching gas containing argon gas as a main component. If the insulating layer 12 is also removed by dry etching using an etching gas containing argon gas as a main component to prevent the manufacturing process from becoming complicated, the via wiring 26 may be formed recessed from the upper surface 11 of the support substrate 10, as shown in FIG. 7( a) of the comparative example. In this case, a break 50 may occur in the wiring 40. Therefore, when the piezoelectric layer 14 is a lithium tantalate layer or a lithium niobate layer, it is preferable to make the via wiring 26 protrude from the upper surface 11 of the support substrate 10 to prevent the wiring 40 from breaking.

[0046] In Example 1, the support substrate 10 is a sapphire substrate, an alumina substrate, a spinel substrate, a quartz substrate, a crystal substrate, or a silicon substrate, and the via wiring 26 is primarily composed of copper, silver, or gold. In this case, as shown in FIG. 7(a) of the comparative example, over-etching can easily cause the via wiring 26 to be recessed from the upper surface 11 of the support substrate 10, which can result in a break 50 in the wiring 40. Therefore, in such a case, it is preferable to make the via wiring 26 protrude from the upper surface 11 of the support substrate 10 to prevent the wiring 40 from being broken. Note that, when a certain layer is composed primarily of a certain element, it is acceptable for the layer to contain intentional or unintentional impurities other than the main component. When a certain element is the main component of a certain layer, the concentration of the certain element is, for example, 50 atomic % or more, for example, 80 atomic % or more. [Example]

[0047] FIG. 9 is a cross-sectional view of an acoustic wave device 200 in accordance with a second embodiment. FIG. 10(a) is a plan view of the acoustic wave device 200 in accordance with the second embodiment, and FIG. 10(b) is an enlarged cross-sectional view of the vicinity of a columnar body 60 in FIG. 9. FIG. 10(a) mainly illustrates an annular body 62 and a columnar body 60. As shown in FIGS. 9 and 10(a), the piezoelectric layer 14 and the insulating layer 12 are removed from the periphery of the support substrate 10. The annular body 62 is provided on the periphery of the support substrate 10. The annular body 62 is provided to surround the acoustic wave element 30 in a plan view. The annular body 62 is, for example, a metal layer. For example, a copper layer having a thickness of approximately 20 μm and a nickel layer having a thickness of approximately 2.5 μm are laminated from the support substrate 10 side.

[0048] A lid 70 (covering body) is provided on the annular body 62, with a gap 64 sandwiched between it and the support substrate 10. The lid 70 is made of, for example, metal, such as a Kovar plate with a thickness of about 30 μm. A metal layer 72 is provided on the underside of the lid 70. The metal layer 72 is, for example, a gold layer. The annular body 62 and the metal layer 72 are joined by a solder layer 66. The solder layer 66 is, for example, an AuSn layer with a thickness of about 4 μm. The annular body 62 and the lid 70 seal the acoustic wave element 30 within the gap 64. The annular body 62 is electrically connected to the ground terminal 24 through the via wiring 26.

[0049] A pillar 60 is provided in the gap 64 between the via wiring 26 and the lid 70. The pillar 60 is a metal layer such as a gold layer or copper layer with a height of, for example, about 20 μm to 35 μm, and an example is a copper layer with a height of about 20 μm. The diameter of the pillar 60 is, for example, about 60 μm. The pillar 60 is provided on the via wiring 26 via the wiring 40. The pillar 60 is in contact with, for example, the metal layer 72. The pillar 60 is electrically connected to the ground terminal 24 via the via wiring 26. The pillar 60 is provided to prevent the lid 70 from collapsing and / or to strengthen the ground of the lid 70.

[0050] 10(a) and 10(b), the pillar-shaped body 60 is provided so as to cover the via wiring 26 in a plan view. For example, the pillar-shaped body 60 is provided so as to completely cover the via wiring 26, but it is also possible that the pillar-shaped body 60 does not cover a part of the via wiring 26. A lower surface 61 of the pillar-shaped body 60 positioned around the via wiring 26 is located closer to the support substrate 10 than an upper surface 41 of the wiring 40 on the via wiring 26. Therefore, the wiring 40 is provided so as to protrude into the pillar-shaped body 60.

[0051] According to the second embodiment, a pillar 60 is provided between the via wiring 26 and the lid 70 in the gap 64. The pillar 60 is provided to cover the upper surface of the via wiring 26 in a plan view, and a lower surface 61 located around the via wiring 26 is located closer to the support substrate 10 than an upper surface 41 of the wiring 40 on the via wiring 26. This creates an anchor effect between the pillar 60 and the wiring 40, thereby improving the adhesion strength between the pillar 60 and the wiring 40. [Example]

[0052] FIG. 11 is a circuit diagram of a filter 300 according to a third embodiment. As shown in FIG. 11, one or more series resonators S1 to S4 are connected in series between an input terminal Tin and an output terminal Tout. One or more parallel resonators P1 to P3 are connected in parallel between the input terminal Tin and the output terminal Tout. At least one of the resonators of the filter 300 according to the third embodiment may be formed by the acoustic wave device 30 of the first or second embodiment. The numbers of the series resonators and parallel resonators can be set as appropriate. Although a ladder-type filter is shown as an example of the filter, a multi-mode filter may also be used. [Example]

[0053] FIG. 12 is a circuit diagram of a duplexer 400 according to a fourth embodiment. As shown in FIG. 12, a transmit filter 80 is connected between a common terminal Ant and a transmit terminal Tx. A receive filter 82 is connected between the common terminal Ant and a receive terminal Rx. The transmit filter 80 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 82 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 80 and the receive filter 82 can be the filter 300 according to the third embodiment. Although a duplexer has been described as an example of a multiplexer in the fourth embodiment, a triplexer or a quadplexer may also be used.

[0054] 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]

[0055] 10 Support substrate 11 Top side 12 Insulating layer 14 Piezoelectric layer 16 Boundary layer 18 Temperature compensation layer 20 Metal Film 22 Protective film 24 terminals 25 Top 26 Via wiring 27 Slope 28 holes 29 areas 30 Acoustic Wave Device 32 IDT 34 Reflector 36 Comb-shaped electrode 37 Electrode finger 38 Busbar 40 Wiring 41 Top surface 42 Adhesion layer 44 Low resistance layer 50 Disconnection 60 columnar body 61 Bottom surface 62 Annular 64 void 66 Solder layer 70 Lid 72 Metal layer 80 Transmission Filter 82 Receive Filter 100, 200, 500 Acoustic Wave Devices 300 filters 400 Duplexer

Claims

1. A support substrate; a via wiring that penetrates the support substrate and protrudes from an upper surface of the support substrate; a piezoelectric layer provided on the support substrate and not overlapping the via wiring in a plan view; an insulating layer provided between the support substrate and the piezoelectric layer, the insulating layer not overlapping the via wiring in a plan view; an acoustic wave element provided on the piezoelectric layer; an interconnection that is provided from above the via interconnection to above the piezoelectric layer and electrically connects the via interconnection to the acoustic wave element;

2. The acoustic wave device according to claim 1 , wherein the via wiring has a flat upper surface and an inclined surface that is located around the upper surface and inclined obliquely upward toward the upper surface.

3. The acoustic wave device according to claim 1 , wherein an upper surface of the support substrate that is not covered with the insulating layer in a plan view is recessed relative to an upper surface of the support substrate that is covered with the insulating layer.

4. 3. The acoustic wave device according to claim 1, wherein the maximum thickness of the upper surface of the via wiring protruding from the upper surface of the support substrate is 2.5 times or less the thickness of the wiring.

5. The acoustic wave device according to claim 1 , wherein the piezoelectric layer is a lithium tantalate layer or a lithium niobate layer.

6. the support substrate is a sapphire substrate, an alumina substrate, a spinel substrate, a quartz substrate, a crystal substrate, or a silicon substrate; The acoustic wave device according to claim 5 , wherein the via wiring is mainly made of copper, silver, or gold.

7. an annular body provided on the support substrate so as to surround the acoustic wave element in a plan view; a lid provided on the annular body with a gap sandwiched between the lid and the support substrate, the lid sealing the acoustic wave element in the gap; 3. The acoustic wave device of claim 1, further comprising: a columnar body provided in the gap between the via wiring and the lid, covering the upper surface of the via wiring in a planar view, and having a lower surface positioned around the via wiring and closer to the support substrate than the upper surface of the wiring on the via wiring.

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

9. A multiplexer including the filter of claim 8.

10. forming via wiring in a support substrate; forming an insulating layer on the support substrate after forming the via wiring; forming a piezoelectric layer on the insulating layer; forming an acoustic wave element on the piezoelectric layer; removing the piezoelectric layer and the insulating layer in a region overlapping with the via wiring and in a region surrounding the via wiring in a plan view, and causing the via wiring to protrude from the upper surface of the support substrate; A method for manufacturing an elastic wave device, comprising a step of protruding the via wiring from the upper surface of the support substrate, and then forming wiring that extends from above the via wiring to above the piezoelectric layer and electrically connects the via wiring to the elastic wave element.

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