JP7370146B2 - Acoustic wave devices, filters and multiplexers - Google Patents

Description

TECHNICAL FIELD The present invention relates to acoustic wave devices, filters, and multiplexers, and for example, to acoustic wave devices, filters, and multiplexers having a piezoelectric substrate bonded onto a support substrate.

An acoustic wave device is known in which frequency-temperature characteristics are improved by using a bonded substrate in which a piezoelectric substrate is bonded to the upper surface of a support substrate (for example, Patent Document 1). In addition, in a configuration in which the piezoelectric substrate is bonded to a part of the top surface of the support substrate and the wiring extends onto the piezoelectric substrate from an area on the top surface of the support substrate that is not bonded to the piezoelectric substrate, the side surface of the piezoelectric substrate may be formed into an inclined surface. It is known that disconnection of wiring can be suppressed by doing so (for example, Patent Document 2).

Japanese Patent Application Publication No. 2004-343359 Japanese Patent Application Publication No. 2013-21387

Since the piezoelectric substrate is fragile, if a metal layer or the like is provided on the piezoelectric substrate, cracks may occur in the piezoelectric substrate due to thermal stress between the support substrate, the piezoelectric substrate, and the metal layer.

The present invention was made in view of the above problems, and an object of the present invention is to suppress deterioration of a piezoelectric substrate.

The present invention includes a support substrate, a first piezoelectric substrate bonded onto the support substrate, an acoustic wave element provided on the first piezoelectric substrate, and a support substrate that surrounds the elastic wave element in a plan view. an annular metal layer provided on a supporting substrate with a space between the first piezoelectric substrate and the first piezoelectric substrate; a chip mounted on the first piezoelectric substrate so as to face the first piezoelectric substrate with a gap in between; a sealing metal layer that is bonded to the annular metal layer and seals the acoustic wave element in the gap; and a second piezoelectric substrate that surrounds the first piezoelectric substrate and is spaced apart from the first piezoelectric substrate. and, the annular metal layer is an acoustic wave device provided on the second piezoelectric substrate .

In the above configuration, the linear expansion coefficient of the sealing metal layer may be larger than that of the first piezoelectric substrate.

In the above structure, the sealing metal layer may be made of solder containing tin as a main component.

In the above structure, the first piezoelectric substrate may be a lithium tantalate substrate or a lithium niobate substrate.

The above structure may include a lid provided on the chip and the sealing metal layer.

In the above configuration, the sealing metal layer may be configured not to be bonded to the support substrate and the first piezoelectric substrate except for the annular metal layer.

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

The present invention is a multiplexer including the above filter.

According to the present invention, deterioration of the piezoelectric substrate can be suppressed.

FIG. 1(a) is a cross-sectional view of an acoustic wave device according to Example 1, and FIG. 1(b) is a plan view. 2(a) is a plan view of the acoustic wave element 12 in Example 1, and FIG. 2(b) is a sectional view of the acoustic wave element 22. 3(a) to 3(d) are cross-sectional views (part 1) showing the method for manufacturing the acoustic wave device according to the first embodiment. FIGS. 4(a) to 4(c) are cross-sectional views (part 2) showing the method for manufacturing the acoustic wave device according to the first embodiment. FIGS. 5(a) to 5(c) are cross-sectional views (part 3) showing the method for manufacturing the acoustic wave device according to the first embodiment. 6(a) is a cross-sectional view of an acoustic wave device according to Comparative Example 1, and FIG. 6(b) is a schematic diagram of a cross-sectional SEM image of Comparative Example 1. FIG. 7 is a cross-sectional view of an acoustic wave device according to Modification 1 of Example 1. FIGS. 8A to 8D are cross-sectional views showing a method for manufacturing an acoustic wave device according to Modification 1 of Example 1. FIGS. FIG. 9 is a cross-sectional view of an acoustic wave device according to a second modification of the first embodiment. 10(a) to 10(c) are cross-sectional views showing a method of manufacturing an acoustic wave device according to a second modification of the first embodiment. FIG. 11A is a circuit diagram of a filter according to a second embodiment, and FIG. 11B is a circuit diagram of a duplexer according to a first modification of the second embodiment.

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

FIG. 1(a) is a cross-sectional view of an acoustic wave device according to Example 1, and FIG. 1(b) is a plan view. FIG. 1(b) shows the piezoelectric substrate 10b, the space 15, and the annular metal layer 32. As shown in FIGS. 1(a) and 1(b), the substrate 10 includes a support substrate 10a and a piezoelectric substrate 10b. The support substrate 10a is, for example, a sapphire substrate, an alumina substrate, a spinel substrate, a crystal substrate, or a silicon substrate. The piezoelectric substrate 10b is, for example, a lithium tantalate substrate or a lithium niobate substrate. The piezoelectric substrate 10b is bonded to the upper surface of the support substrate 10a. The linear expansion coefficient of the support substrate 10a is smaller than that of the piezoelectric substrate 10b. An insulator layer such as silicon oxide or aluminum nitride may be provided between the piezoelectric substrate 10b and the support substrate 10a.

An acoustic wave element 12 and wiring 14 are provided on the upper surface of the substrate 10. Terminals 18 are provided on the lower surface of the substrate 10. The terminal 18 is a foot pad for connecting the acoustic wave elements 12 and 22 to the outside. A via wiring 16 is provided that penetrates the substrate 10. The via wiring 16 electrically connects the terminal 18 and the wiring 14.

The piezoelectric substrate 10b is removed at the periphery of the substrate 10. An annular metal layer 32 is provided on the support substrate 10a so as to surround the acoustic wave element 12. A space 15 exists between the annular metal layer 32 and the piezoelectric substrate 10b. The space 15 is, for example, a void. The wiring 14, the via wiring 16, the terminal 18, and the annular metal layer 32 are, for example, metal layers such as a copper layer, an aluminum layer, or a gold layer.

An annular metal layer 34 is provided on the annular metal layer 32 . The annular metal layer 34 includes, for example, a titanium layer, a nickel layer, and a gold layer from the annular metal layer 32 side. The titanium layer, which is one of the annular metal layers 34, is an adhesion layer between the annular metal layers 32 and 34. The nickel layer is a barrier layer that suppresses mutual diffusion between the sealing metal layer 30 and the annular metal layer 32. The gold layer has good wettability with the sealing metal layer 30 and joins the sealing metal layer 30 to the annular metal layer 34.

A substrate 20 is mounted on the substrate 10. An acoustic wave element 22 and wiring 24 are provided on the lower surface of the substrate 20. The wiring 24 is, for example, a metal layer such as a copper layer, an aluminum layer, or a gold layer. The board 20 is flip-chip mounted (face-down mounted) on the board 10 via bumps 28. Bump 28 connects to wirings 14 and 24. Bumps 28 are, for example, gold bumps, solder bumps, or copper bumps.

A sealing metal layer 30 is provided on the substrate 10 so as to surround the substrate 20. The sealing metal layer 30 is, for example, solder containing tin. The sealing metal layer 30 is joined to the annular metal layer 34. A flat lid 36 is provided on the upper surface of the substrate 20 and the upper surface of the sealing metal layer 30. The lid 36 is, for example, a metal plate such as a Kovar plate or an insulating plate. A protective film 38 is provided to cover the lid 36 and the sealing metal layer 30. The protective film 38 is a metal film such as a nickel film or an insulating film.

The acoustic wave element 12 faces the substrate 20 with a gap 26 in between. The acoustic wave element 22 faces the piezoelectric substrate 10b with a gap 26 in between. Acoustic wave elements 12 and 22 are sealed by sealing metal layer 30, substrate 10, substrate 20, and lid 36. Bump 28 is surrounded by void 26. The terminal 18 is electrically connected to the acoustic wave element 12 via the via wiring 16 and the wiring 14, and further electrically connected to the acoustic wave element 22 via the bump 28 and the wiring 24.

The thickness of the support substrate 10a is, for example, 50 μm to 200 μm. The thickness of the piezoelectric substrate 10b is, for example, 0.5 μm to 20 μm, which is, for example, less than the wavelength of an elastic wave. The thickness of the annular metal layer 32 is approximately equal to the thickness of the piezoelectric substrate 10b. The thickness of the annular metal layer 34 is, for example, 1 μm to 5 μm. The width of the annular metal layers 32 and 34 is, for example, 25 μm to 100 μm. The thickness of the bump 28 is, for example, 10 μm to 20 μm. The thickness of the substrate 20 is, for example, 50 μm to 200 μm. The width L of the space 15 is, for example, 1 μm to 50 μm.

2(a) is a plan view of the acoustic wave element 12 in Example 1, and FIG. 2(b) is a sectional view of the acoustic wave element 22. As shown in FIG. 2(a), the acoustic wave element 12 is a surface acoustic wave resonator. An IDT (Interdigital Transducer) 40 and a reflector 42 are formed on the piezoelectric substrate 10b of the substrate 10. The IDT 40 has a pair of comb-shaped electrodes 40a facing each other. The comb-shaped electrode 40a has a plurality of electrode fingers 40b and a bus bar 40c connecting the plurality of electrode fingers 40b. Reflectors 42 are provided on both sides of the IDT 40. The IDT 40 excites surface acoustic waves in the piezoelectric substrate 10b. The wavelength of the elastic wave is approximately equal to the pitch of the electrode fingers 40b of one of the pair of comb-shaped electrodes 40a. That is, the wavelength of the elastic wave is approximately equal to twice the pitch of the electrode fingers 40b of the pair of comb-shaped electrodes 40a. The IDT 40 and the reflector 42 are formed of, for example, an aluminum film or a copper film. A protective film or a temperature compensation film may be provided on the piezoelectric substrate 10b so as to cover the IDT 40 and the reflector 42.

As shown in FIG. 2(b), the acoustic wave element 22 is a piezoelectric thin film resonator. A piezoelectric film 46 is provided on the substrate 20. A lower electrode 44 and an upper electrode 48 are provided so as to sandwich the piezoelectric film 46 therebetween. A gap 45 is formed between the lower electrode 44 and the substrate 20. A region where the lower electrode 44 and the upper electrode 48 face each other with at least a portion of the piezoelectric film 46 in between is a resonance region 47 . In the resonance region 47, the lower electrode 44 and the upper electrode 48 excite elastic waves in the thickness longitudinal vibration mode within the piezoelectric film 46. The substrate 20 is, for example, a sapphire substrate, a spinel substrate, an alumina substrate, a glass substrate, a crystal substrate, or a silicon substrate. The lower electrode 44 and the upper electrode 48 are, for example, metal films such as ruthenium films. The piezoelectric film 46 is, for example, an aluminum nitride film. Instead of the void 45, an acoustic reflection film that reflects elastic waves may be provided.

Acoustic wave elements 12 and 22 include electrodes that excite elastic waves. For this reason, the elastic wave elements 12 and 22 are covered with a void 26 so as not to limit the elastic waves.

[Production method of Example 1]
FIGS. 3(a) to 5(c) are cross-sectional views showing the method for manufacturing the acoustic wave device according to the first embodiment. As shown in FIG. 3A, the upper surface of the support substrate 10a is irradiated with, for example, a laser beam to form a via 17a. As shown in FIG. 3B, the lower surface of the piezoelectric substrate 10b is bonded to the upper surface of the support substrate 10a at room temperature using, for example, a surface activation method. The support substrate 10a and the piezoelectric substrate 10b may be directly bonded via an amorphous layer of several nanometers or the like, or may be bonded with an adhesive or the like. An insulating layer may be provided between the support substrate 10a and the piezoelectric substrate 10b.

As shown in FIG. 3C, the piezoelectric substrate 10b is polished using, for example, a CMP (Chemical Mechanical Polishing) method. This allows the piezoelectric substrate 10b to have a desired thickness. As shown in FIG. 3(d), the piezoelectric substrate 10b is removed, for example, by etching to form openings 17b and 17c. The opening 17b communicates with the via 17a and is formed larger than the via 17a. A via 17 that penetrates the substrate 10 is formed by the via 17a and the opening 17b. The opening 17c is formed to surround the piezoelectric substrate 10b.

As shown in FIG. 4A, a seed layer 31a is formed on the support substrate 10a and the piezoelectric substrate 10b using, for example, a sputtering method. The seed layer 31a is, for example, a titanium layer and a copper layer from the substrate 10 side. As shown in FIG. 4B, a metal layer 31 is formed on the seed layer 31a using, for example, a plating method. The metal layer 31 is, for example, a copper layer. From FIG. 4B onward, illustration of the seed layer 31a is omitted. As shown in FIG. 4C, the upper surface of the metal layer 31 is planarized using, for example, a CMP method so that the surface of the piezoelectric substrate 10b is exposed. As a result, via wiring 16 and annular metal layer 32 are formed. The thickness of the annular metal layer 32 is approximately equal to the thickness of the piezoelectric substrate 10b.

As shown in FIG. 5(a), an acoustic wave element 12 is formed on a piezoelectric substrate 10b. Wiring 14 is formed on piezoelectric substrate 10b and via wiring 16. An annular metal layer 34 is formed on the annular metal layer 32 . As shown in FIG. 5(b), the inner region of the annular metal layer 32 is removed using an etching method. Thereby, a space 15 is formed between the annular metal layer 32 and the piezoelectric substrate 10b. As shown in FIG. 5(c), the substrate 20 is flip-chip mounted on the substrate 10 via the bumps 28. As a result, the acoustic wave elements 12 and 22 face each other with the air gap 26 in between.

Thereafter, a sealing metal layer 30 made of, for example, tin-silver solder is formed to surround the substrate 20. The sealing metal layer 30 is joined to the annular metal layer 34 . A lid 36 is provided on the sealing metal layer 30 and the substrate 20. The lid 36 may not be provided. The lower surface of the support substrate 10a is polished using a CMP method or the like. As a result, the via wiring 16 is exposed on the lower surface of the support substrate 10a. A terminal 18 that contacts the via wiring 16 is formed. Cut the substrate 10. Thereby, the acoustic wave device is separated into pieces. A protective film 38 surrounding the sealing metal layer 30 and the lid 36 is formed. As a result, the acoustic wave devices shown in FIGS. 1(a) and 1(b) are manufactured.

[Comparative example 1]
FIG. 6(a) is a cross-sectional view of an acoustic wave device according to Comparative Example 1. As shown in FIG. 6A, in the acoustic wave device of Comparative Example 1, the space 15 is not provided in the piezoelectric substrate 10b, and the annular metal layer 32 and the piezoelectric substrate 10b are in contact with each other.

FIG. 6(b) is a schematic diagram of a cross-sectional SEM (Scanning Electron Microscope) image of Comparative Example 1. In the produced acoustic wave device, the support substrate 10a is a sapphire substrate with a thickness of about 100 μm. The piezoelectric substrate 10b is a 42° rotated Y-cut, X-propagating lithium tantalate substrate with a thickness of approximately 20 μm. The annular metal layer 32 is a copper layer with a thickness of approximately 20 μm. The annular metal layer 34 is a laminated film of a titanium layer with a thickness of approximately 0.1 μm, a nickel layer with a thickness of approximately 2.5 μm, and a gold layer with a thickness of approximately 0.2 μm. The sealing metal layer 30 is a tin-silver layer. As shown in FIG. 6(b), a crack 60 has occurred in the piezoelectric substrate 10b.

Table 1 is a table showing linear expansion coefficients of main materials. Lithium tantalate (LT), sapphire, copper (Cu), nickel (Ni), tin (Sn), Sn-0.3Ag-0.7Cu alloy, Sn-3.5Ag alloy and Sn-3Ag-0.5Cu alloy It shows the coefficient of linear expansion of . X, Y, and Z of lithium tantalate indicate linear expansion coefficients in the X-axis direction, Y-axis direction, and Z-axis direction of crystal orientation. Alloy numbers indicate weight percent.

As shown in Table 1, there is a large difference in linear expansion coefficient between the materials. In particular, when solder containing tin is used as the sealing metal layer 30, the linear expansion coefficient of the sealing metal layer 30 is much larger than that of the piezoelectric substrate 10b. This applies thermal stress to the piezoelectric substrate 10b. Since the piezoelectric substrate 10b is more brittle than metal and the support substrate 10a, it is thought that if thermal stress is applied to the piezoelectric substrate 10b, deterioration such as cracking will occur.

According to Example 1, the piezoelectric substrate 10b (first piezoelectric substrate) is bonded onto the support substrate 10a. The annular metal layers 32 and 34 are provided on the support substrate 10a and surround the acoustic wave element 12 in plan view. The substrate 20 (chip) is mounted on the piezoelectric substrate 10b so as to face the piezoelectric substrate 10b with a gap 26 in between. The sealing metal layer 30 surrounds the substrate 20 and is bonded to the annular metal layer 34 to seal the acoustic wave element 12 in the gap 26 . In such an acoustic wave device, the annular metal layers 32 and 34 are provided with an interval (space 15) from the piezoelectric substrate 10b in plan view. Thereby, thermal stress caused by the difference in linear expansion coefficient between the sealing metal layer 30 and the piezoelectric substrate 10b can be suppressed from being applied to the piezoelectric substrate 10b. Therefore, deterioration of the piezoelectric substrate 10b such as introduction of cracks 60 into the piezoelectric substrate 10b can be suppressed.

If the linear expansion coefficient of the sealing metal layer 30 is larger than the linear expansion coefficient of the piezoelectric substrate 10b, stress is likely to be applied to the piezoelectric substrate 10b. Therefore, it is preferable to provide the space 15. In particular, when the sealing metal layer 30 is made of solder containing tin as a main component, the linear expansion coefficient of the sealing metal layer 30 becomes large. Therefore, it is preferable to provide the space 15. Incidentally, the term "containing tin as a main component" means that 50% by weight or more is tin, and the content of tin is preferably 80% by weight or more. When the piezoelectric substrate 10b is a lithium tantalate substrate or a lithium niobate substrate, when stress is applied to the piezoelectric substrate 10b, the piezoelectric substrate 10b tends to deteriorate. Therefore, it is preferable to provide the space 15.

The piezoelectric substrate 10b is not provided between the annular metal layer 32 and the support substrate 10a. Thereby, deterioration of the piezoelectric substrate 10b can be suppressed. When the piezoelectric substrate 10b is in contact with the support substrate 10a, the annular metal layer 32 is provided in contact with the support substrate 10a. When an insulating film is provided between the piezoelectric substrate 10b and the support substrate 10a, the annular metal layer 32 may be in contact with the support substrate 10a or the insulating film.

The sealing metal layer 30 is not bonded to the support substrate 10a and the piezoelectric substrate 10b except for the annular metal layers 32 and 34. Thereby, deterioration of the piezoelectric substrate 10b can be suppressed.

Loss can be suppressed by making the thickness of the piezoelectric substrate 10b equal to or less than the wavelength of the elastic wave. Further, warping of the support substrate 10a can be suppressed. Thereby, stress applied to the bumps 28 can be suppressed. Furthermore, the height can be reduced. When an insulating film is provided between the support substrate 10a and the piezoelectric substrate 10b, the distance between the upper surface of the support substrate 10a and the upper surface of the piezoelectric substrate 10b is preferably twice or less the wavelength of the elastic wave. Thereby, loss can be suppressed.

The width L of the space 15 is preferably at least 1 μm, more preferably at least 5 μm, and preferably at least the thickness of the piezoelectric substrate 10b. Thereby, deterioration of the piezoelectric substrate 10b can be suppressed. The width L of the space 15 is preferably 100 μm or less, more preferably 20 μm or less. This allows the elastic wave device to be miniaturized.

[Modification 1 of Example 1]
FIG. 7 is a cross-sectional view of an acoustic wave device according to Modification 1 of Example 1. As shown in FIG. 7, in the first modification of the first embodiment, a piezoelectric substrate 10c is provided in place of the annular metal layer 32. An annular metal layer 34 is provided on the piezoelectric substrate 10c. The piezoelectric substrate 10c is made of the same material and has the same thickness as the piezoelectric substrate 10b. The other configurations are the same as those in Example 1, and their explanation will be omitted.

FIGS. 8A to 8D are cross-sectional views showing a method for manufacturing an acoustic wave device according to Modification 1 of Example 1. FIGS. As shown in FIG. 8(a), the steps of FIG. 3(a) to FIG. 3(d) of Example 1 are performed. At this time, an opening 17d that becomes the space 15 is formed instead of the opening 17c.

As shown in FIG. 8(b), the steps from FIG. 4(a) to FIG. 4(c) of Example 1 are performed. As a result, the sacrificial metal layer 33 is embedded in the opening 17d. As shown in FIG. 8(c), the process of FIG. 5(a) of Example 1 is performed. Thereby, an annular metal layer 34 is formed on the piezoelectric substrate 10c. As shown in FIG. 8C, the sacrificial metal layer 33 is removed by, for example, an etching method. As a result, a space 15 is formed. Thereafter, the process of FIG. 5(c) of Example 1 is performed to manufacture the acoustic wave device of FIG. 7.

According to the first modification of the first embodiment, the piezoelectric substrate 10c (second piezoelectric substrate) surrounds the piezoelectric substrate 10b and is spaced apart from the piezoelectric substrate 10b. As a result, even if the annular metal layer 34 is provided on the piezoelectric substrate 10b, since the space 15 exists between the piezoelectric substrates 10b and 10c, deterioration of the piezoelectric substrate 10b near the acoustic wave element 12 is suppressed. can. The inner side surface of the piezoelectric substrate 10c may be located inside the inner side surface of the annular metal layer 34. For miniaturization, the distance between the inner side surface of the piezoelectric substrate 10c and the inner side surface of the annular metal layer 34 is preferably 10 μm or less.

[Modification 2 of Example 1]
FIG. 9 is a cross-sectional view of an acoustic wave device according to a second modification of the first embodiment. As shown in FIG. 9, in the second modification of the first embodiment, the annular metal layer 32 is not provided, and the annular metal layer 34 is directly provided on the upper surface of the support substrate 10a. The other configurations are the same as those in Example 1, and their explanation will be omitted.

10(a) to 10(c) are cross-sectional views showing a method of manufacturing an acoustic wave device according to a second modification of the first embodiment. As shown in FIG. 10(a), the steps of FIG. 3(a) to FIG. 4(c) of Example 1 are performed. After that, the annular metal layer 34 is not formed in FIG. 5(a). As shown in FIG. 10(b), the annular metal layer 32 is removed using, for example, an etching method. As a result, an opening 17c is formed in the region where the annular metal layer 32 was formed. As shown in FIG. 10(c), an annular metal layer 34 is formed on the upper surface of the support substrate 10a within the opening 17c. Thereafter, the process of FIG. 5(c) of Example 1 is performed to manufacture the acoustic wave device of FIG. 7.

In the second modification of the first embodiment, the material of the annular metal layer 34 is different from the material of the via wiring 16. Further, the thickness of the annular metal layer 34 is thinner than that of the piezoelectric substrate 10b. When the thickness of the piezoelectric substrate 10b is set to be less than or equal to the wavelength of the elastic wave, the thickness of the annular metal layer 34 may be thicker than the piezoelectric substrate 10b. In this way, the thickness and material of the annular metal layer can be set arbitrarily.

In the first embodiment and its modifications, the piezoelectric thin film resonator is used as the acoustic wave element 22, but the acoustic wave element 22 may be a surface acoustic wave resonator. Although an example of the acoustic wave device 22 has been described as a functional device provided on the lower surface of the substrate 20, the functional device may be a passive device such as an inductor or a capacitor, an active device including a transistor, or a MEMS (Micro Electro Mechanical Systems) device. .

Example 2 is an example of a filter and a duplexer. FIG. 11(a) is a circuit diagram of a filter according to the second embodiment. As shown in FIG. 11(a), one or more series resonators S1 to S4 are connected in series between the input terminal T1 and the output terminal T2. One or more parallel resonators P1 to P4 are connected in parallel between the input terminal T1 and the output terminal T2. The filter of the second embodiment may be formed of the acoustic wave elements 12 and/or 22. The number of series resonators and parallel resonators can be set as appropriate. Although the filter has been described using a ladder filter as an example, the filter may be a multimode filter.

FIG. 11(b) is a circuit diagram of a duplexer according to a first modification of the second embodiment. As shown in FIG. 11(b), a transmission filter 50 is connected between the common terminal Ant and the transmission terminal Tx. A reception filter 52 is connected between the common terminal Ant and the reception terminal Rx. The transmission filter 50 passes a signal in the transmission band among the high frequency signals inputted from the transmission terminal Tx to the common terminal Ant as a transmission signal, and suppresses signals of other frequencies. The reception filter 52 passes a signal in the reception band among the high-frequency signals inputted from the common terminal Ant to the reception terminal Rx as a reception signal, and suppresses signals at other frequencies. At least one of the transmission filter 50 and the reception filter 52 can be the filter of the second embodiment. Alternatively, the transmission filter 50 may be formed of the elastic wave element 12 and the reception filter 52 may be formed of the elastic wave element 22.

Although a duplexer has been described as an example of a multiplexer, a triplexer or a 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 these specific embodiments, and various modifications and variations can be made within the scope of the gist of the present invention as described in the claims. Changes are possible.

10a Support substrate 10b, 10c Piezoelectric substrate 12, 22 Acoustic wave element 14, 24 Wiring 15 Space 16 Via wiring 18 Terminal 20 Substrate 26 Gap 28 Bump 30 Sealing metal layer 32, 34 Annular metal layer 36 Lid 50 Transmission filter 52 Reception filter

Claims (8)

a support substrate;
a first piezoelectric substrate bonded onto the support substrate;
an acoustic wave element provided on the first piezoelectric substrate;
an annular metal layer provided on the support substrate at a distance from the first piezoelectric substrate so as to surround the acoustic wave element in a plan view;
a chip mounted on the first piezoelectric substrate so as to face the first piezoelectric substrate across a gap;
a sealing metal layer that surrounds the chip and is bonded to the annular metal layer and seals the acoustic wave element in the gap;
a second piezoelectric substrate surrounding the first piezoelectric substrate and spaced apart from the first piezoelectric substrate;
Equipped with
The annular metal layer is an acoustic wave device provided on the second piezoelectric substrate. The acoustic wave device according to claim 1, wherein the linear expansion coefficient of the sealing metal layer is larger than that of the first piezoelectric substrate. The acoustic wave device according to claim 1 , wherein the sealing metal layer is a solder containing tin as a main component. The acoustic wave device according to claim 3 , wherein the first piezoelectric substrate is a lithium tantalate substrate or a lithium niobate substrate. The acoustic wave device according to claim 1 , further comprising a lid provided on the chip and the sealing metal layer. The acoustic wave device according to any one of claims 1 to 5 , wherein the sealing metal layer is not bonded to the support substrate and the first piezoelectric substrate except at the annular metal layer. A filter comprising the elastic wave device according to any one of claims 1 to 6 . A multiplexer comprising a filter according to claim 7 .

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