JP7808401B2 - Acoustic wave device, filter, multiplexer, and method for manufacturing an acoustic wave device - Google Patents

Description

The present invention relates to acoustic wave devices, filters, multiplexers, and methods for manufacturing acoustic wave devices.

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 (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2017-022501

In a structure in which a piezoelectric layer is provided on a support substrate via an insulating layer, wiring is provided from above the via wiring to above the piezoelectric layer to electrically connect the via wiring that penetrates the support substrate to the acoustic wave element provided on the piezoelectric layer. In this case, wiring can break when it is pulled out from above the via wiring.

The present invention was developed in consideration of the above issues, and aims to prevent wiring breakage.

The present invention provides an acoustic wave device comprising a support substrate, via wiring that penetrates the support substrate and protrudes from the upper surface of the support substrate, a piezoelectric layer that is provided on the support substrate and does not overlap the via wiring in a planar view, an insulating layer that is provided between the support substrate and the piezoelectric layer and does not overlap the via wiring in a planar view, an acoustic wave element that is provided on the piezoelectric layer, and wiring that is provided from above the via wiring to above the piezoelectric layer and electrically connects the via wiring to the acoustic wave element.

In the above configuration, the via wiring can be configured to have a flat upper surface and an inclined surface located around the upper surface and inclined obliquely upward toward the upper surface.

In the above configuration, the upper surface of the support substrate that is not covered with the insulating layer in a plan view can be recessed relative to the upper surface of the support substrate that is covered with the insulating layer.

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

In the above configuration, the piezoelectric layer can be a lithium tantalate layer or a lithium niobate layer.

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

The above configuration can include an annular body provided on the support substrate and surrounding the acoustic wave element in a plan view; a lid provided on the annular body with a gap between it and the support substrate, sealing the acoustic wave element in the gap; and a pillar-shaped body provided in the gap between the via wiring and the lid, covering the upper surface of the via wiring in a plan view, and having a lower surface located around the via wiring and closer to the support substrate than the upper surface of the wiring on the via wiring.

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

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

The present invention relates to a method for manufacturing an acoustic wave device, comprising the steps of: 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 from an area that overlaps with the via wiring in a planar view and an area surrounding the via wiring, and causing the via wiring to protrude from the upper surface of the support substrate; and, after causing the via wiring to protrude from the upper 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.

This invention makes it possible to prevent wiring breakage.

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

An embodiment of the present invention will be described below with reference to the drawings.

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 compensation 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 underside of the support substrate 10 and is electrically connected to the via wiring 26.

The piezoelectric layer 14 and insulating layer 12 have been removed in region 29. 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 uneven in both the portion covered with insulating layer 12 and the portion not covered with insulating layer 12. If the upper surface 11 of the support substrate 10 is uneven, the 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 the via wiring 26 in region 29, across the side surfaces of the insulating layer 12 and piezoelectric layer 14, and onto the piezoelectric layer 14. The wiring 40 has an adhesive layer 42 and a low-resistance layer 44 provided on the adhesive layer 42 and having a lower electrical resistivity than the adhesive layer 42. The wiring 40 electrically connects the acoustic wave element 30 and the via wiring 26. The electrical connection only needs to be such that there is conduction in either DC or AC.

As shown in FIG. 1(b), in region 29, the upper surface 25 of the via wiring 26 protrudes from the upper surface 11 of the support substrate 10. The via wiring 26 has, as a surface protruding from the upper surface 11 of the support substrate 10, a substantially flat upper surface 25 and an inclined surface 27 located around the upper surface 25 and inclined so as to rise toward the upper surface 25. The inclination angle θ of the inclined surface 27 is, for example, approximately 5° to 45°. The wiring 40 is formed along the upper surface 25 and inclined surface 27 of the via wiring 26.

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 uneven, 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 to completely cover the via wiring 26 in a planar view.

The support substrate 10 is, for example, a sapphire substrate, alumina substrate, spinel substrate, quartz substrate, quartz 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 Al ₂ O ₃ , the alumina substrate is a substrate mainly composed of polycrystalline Al ₂ O ₃ , and the spinel substrate is a substrate mainly composed of single-crystal or polycrystalline MgAl ₂ O _4. The quartz substrate is a substrate mainly composed of amorphous SiO ₂ , the quartz substrate is a substrate mainly composed of single-crystal SiO ₂ , and the silicon substrate is a substrate mainly composed of single-crystal or polycrystalline Si. The insulating layer 12 is, for example, approximately 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. The 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 the temperature compensating layer 18. The 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 the temperature compensating layer 18 is opposite to the sign of the temperature coefficient of the elastic constant of the piezoelectric layer 14.

The piezoelectric layer 14 is, for example, a single-crystal lithium tantalate layer or a single-crystal lithium niobate layer, an example of which is a rotated Y-cut X-propagation lithium tantalate layer with 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. An example of the bonding layer is an aluminum oxide film with a thickness of 10 nm.

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 with a thickness of 200 nm. The low-resistance layer 44 is, for example, a gold layer, for example, a gold layer with a thickness of 1000 nm. The via wiring 26 is, for example, a copper layer, a silver layer, or a gold layer with a maximum diameter of approximately 20 μm to 60 μm, for example, a copper layer with 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. For example, the terminal 24 is formed by stacking, from the support substrate 10 side, a copper film with a thickness of 2 μm, a nickel film with a thickness of 5 μm, and a gold film with a thickness of 0.3 μm.

Figure 2 is a plan view of a portion of the acoustic wave device 100 according to the first embodiment. Figure 2 shows the vicinity of the via wiring 26. As shown in Figure 2, the via wiring 26 is provided on the support substrate 10 in an area 29 where the piezoelectric layer 14 and the insulating layer 12 (not shown in Figure 2) have been removed. The width of the wiring 40 is, for example, larger than the via wiring 26. In a planar 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 the via wiring 26.

Figure 3 is a plan view of the acoustic wave element 30 in Example 1. As shown in Figure 3, the acoustic wave element 30 is a surface acoustic wave resonator. An IDT (Interdigital Transducer) 32 and a reflector 34 are formed on the 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.

[Manufacturing method]
4A to 5C are cross-sectional views illustrating a manufacturing method of the acoustic wave device 100 according to the first embodiment. As shown in FIG. 4A, a hole 28 is formed in the support substrate 10. At this stage, the hole 28 does not necessarily have to 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.

As shown in Figure 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 to 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.

As shown in FIG. 4(c), the 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.

As shown in FIG. 5A, the piezoelectric layer 14 and insulating layer 12 are removed in a region 29 that overlaps with the via wiring 26 in a planar view and that includes the region surrounding the via wiring 26. The piezoelectric layer 14 and 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 composed of argon gas. If the insulating layer 12 is primarily composed of silicon oxide and/or aluminum oxide, the etching gas is switched from primarily composed of argon gas to primarily composed of 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, the etching rate of the support substrate 10 is faster than the etching rate of the via wiring 26 by performing dry etching using an etching gas primarily composed of a chlorine-based gas following the removal of the insulating layer 12. This results in the upper surface 25 of the via wiring 26 protruding from the upper surface 11 of the support substrate 10. In this way, by etching the support substrate 10 under conditions such that 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 caused to protrude from the upper surface 11 of the support substrate 10. Note that the switch from an etching gas containing argon gas as its main component to an etching gas containing a chlorine-based gas as its 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 via wiring 26 are exposed.

As shown in FIG. 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. Wiring 40 is formed, for example, 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.

As shown in FIG. 5(c), the lower surface of the support substrate 10 is polished or ground. This exposes the via wiring 26 on the lower surface of the support substrate 10. Terminals 24 that connect to the via wiring 26 are formed on the lower surface of the support substrate 10. This completes the acoustic wave device according to Example 1.

[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 Fig. 6(a) and Fig. 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 Example 1, and therefore description thereof will be omitted.

7(a) to 7(c) are cross-sectional views illustrating a manufacturing method for an acoustic wave device 500 according to a comparative example. First, the same steps as those described in FIGS. 4(a) to 4(c) of Example 1 are performed. Then, as shown in FIG. 7(a), 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 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. If 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 in dry etching primarily containing argon gas. As a result, the via wiring 26 is recessed relative to the upper surface 11 of the support substrate 10.

As shown in Figure 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, and onto the piezoelectric layer 14.

As shown in FIG. 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 that connect to the via wiring 26 are formed on the lower surface of the support substrate 10. This completes the acoustic wave device of the comparative example.

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 this 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 where the upper surface 25 of the via wiring 26 contacts the side 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 significantly recessed 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 in the support substrate 10.

On the other hand, according to Example 1, as shown in Figures 1(a) and 1(b), the via wiring 26 is provided so as to protrude from the upper surface 11 of the support substrate 10. This prevents the wiring 40, which extends from above the via wiring 26 to above the piezoelectric layer 14, from having a thin portion. This prevents breaks in the wiring 40.

Furthermore, according to Example 1, as shown in FIG. 5(a), the piezoelectric layer 14 and insulating layer 12 are removed from an area 29 that includes the area overlapping with the via wiring 26 in a plan view and the area surrounding 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), wiring 40 is formed from above the via wiring 26 to above the piezoelectric layer 14. This prevents the wiring 40 from becoming thin in places, and prevents breaks in the wiring 40.

In addition, in Example 1, as shown in Figure 5(a), the piezoelectric layer 14 and 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 too complicated, and reduces the number of manufacturing steps.

In addition, in Example 1, as shown in FIG. 1(b), the via wiring 26 has a substantially flat upper surface 25 and inclined surfaces 27 located around the upper surface 25 and inclined diagonally upward toward the upper surface 25. This prevents the wiring 40 from having thin portions, thereby preventing breaks in the wiring 40. In order to prevent breaks in the wiring 40, the inclination angle θ of the inclined surfaces 27 is preferably 5° to 45°, more preferably 5° to 40°, and even more preferably 5° to 30°.

In addition, in Example 1, as shown in FIG. 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.

In addition, in Example 1, as shown in FIG. 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 prevents the wiring 40 from having thin portions, and prevents 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.

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. To avoid complicating the manufacturing process, the insulating layer 12 is also removed by dry etching using an etching gas containing argon gas as a main component. If this is done, the via wiring 26 may be recessed from the upper surface 11 of the support substrate 10, as shown in Figure 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 have the via wiring 26 protrude from the upper surface 11 of the support substrate 10 to prevent breaks in the wiring 40.

In Example 1, the support substrate 10 is a sapphire substrate, alumina substrate, spinel substrate, quartz substrate, crystal substrate, or silicon substrate, and the via wiring 26 is primarily composed of copper, silver, or gold. In this case, as shown in Figure 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 cases, it is preferable to have the via wiring 26 protrude from the upper surface 11 of the support substrate 10 to prevent breaks in the wiring 40. Note that for a layer to be primarily composed of a certain element, it is acceptable for the layer to contain intentional or unintentional impurities other than the primary component. When a certain element is primarily composed of a certain element in a certain layer, the concentration of the certain element is, for example, 50 atomic % or more, such as 80 atomic % or more.

Figure 9 is a cross-sectional view of an acoustic wave device 200 according to a second embodiment. Figure 10(a) is a plan view of the acoustic wave device 200 according to the second embodiment, and Figure 10(b) is an enlarged cross-sectional view of the vicinity of the columnar body 60 in Figure 9. Figure 10(a) mainly illustrates the annular body 62 and the columnar body 60. As shown in Figures 9 and 10(a), the piezoelectric layer 14 and the insulating layer 12 have been 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, and as an example, from the support substrate 10 side, a copper layer with a thickness of approximately 20 μm and a nickel layer with a thickness of approximately 2.5 μm are laminated.

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 approximately 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 approximately 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 via via wiring 26.

A pillar 60 is provided within 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, approximately 20 μm to 35 μm, and an example is a copper layer with a height of approximately 20 μm. The diameter of the pillar 60 is, for example, approximately 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 grounding of the lid 70.

As shown in Figures 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 for the pillar-shaped body 60 not to cover a portion of the via wiring 26. The lower surface 61 of the pillar-shaped body 60, which is positioned around the via wiring 26, is located closer to the support substrate 10 than the upper surface 41 of the wiring 40 on the via wiring 26. Therefore, the wiring 40 is provided so as to protrude into the interior of the pillar-shaped body 60.

According to Example 2, a pillar 60 is provided in the gap 64 between the via wiring 26 and the lid 70. The pillar 60 is provided to cover the upper surface of the via wiring 26 in a plan view, and the lower surface 61 located around the via wiring 26 is located closer to the support substrate 10 than the 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, improving the adhesion strength between the pillar 60 and the wiring 40.

Figure 11 is a circuit diagram of a filter 300 according to a third embodiment. As shown in Figure 11, one or more series resonators S1 to S4 are connected in series between the input terminal Tin and the 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 in the filter 300 according to the third embodiment may be formed using the acoustic wave element 30 of the first or second embodiment. The number of series resonators and parallel resonators can be set as appropriate. While a ladder-type filter is shown as an example of a filter, a multimode filter may also be used.

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 the common terminal Ant and the transmit terminal Tx. A receive filter 82 is connected between the common terminal Ant and the receive terminal Rx. The transmit filter 80 passes high-frequency signals input from the transmit terminal Tx in the transmit band to the common terminal Ant as transmit signals and suppresses signals of other frequencies. The receive filter 82 passes high-frequency signals input from the common terminal Ant in the receive band to the receive terminal Rx 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. In the fourth embodiment, a duplexer is shown as an example of a multiplexer, but a triplexer or quadplexer may also be used.

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 set forth in the claims.

REFERENCE SIGNS LIST 10 Support substrate 11 Upper surface 12 Insulating layer 14 Piezoelectric layer 16 Boundary layer 18 Temperature compensation layer 20 Metal film 22 Protective film 24 Terminal 25 Upper surface 26 Via wiring 27 Inclined surface 28 Hole 29 Region 30 Acoustic wave element 32 IDT
34 Reflector 36 Comb-shaped electrode 37 Electrode finger 38 Bus bar 40 Wiring 41 Upper surface 42 Adhesion layer 44 Low-resistance layer 50 Disconnection 60 Columnar body 61 Lower surface 62 Ring-shaped body 64 Air gap 66 Solder layer 70 Lid 72 Metal layer 80 Transmitting filter 82 Receiving filter 100, 200, 500 Acoustic wave device 300 Filter 400 Duplexer

Claims (10)

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; The acoustic wave device of claim 1, wherein the via wiring has a flat upper surface and an inclined surface located around the upper surface and inclined obliquely upward toward the upper surface. The acoustic wave device according to claim 1 or 2, wherein the upper surface of the support substrate that is not covered with the insulating layer in a plan view is recessed relative to the upper surface of the support substrate that is covered with the insulating layer. The acoustic wave device of claim 1 or 2, 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. The acoustic wave device of claim 1 or 2, wherein the piezoelectric layer is a lithium tantalate layer or a lithium niobate layer. 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 primarily made of copper, silver, or gold. 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. A filter including the acoustic wave device according to claim 1 or 2. A multiplexer including the filter of claim 8. 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 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.