JP7347955B2 - Acoustic wave devices and their manufacturing methods, filters and multiplexers - Google Patents

Description

The present invention relates to an acoustic wave device, a method of manufacturing the same, a filter, and a multiplexer, and more particularly, to an acoustic wave device whose substrate is sealed with solder, a method of manufacturing the same, a filter, and a multiplexer.

A structure is known in which a second substrate is mounted on a first substrate, and an acoustic wave element is sealed with solder that surrounds the second substrate and is bonded to an annular metal layer on the first substrate (for example, Patent Documents 1 and 2). ).

JP2017-204827A JP 2017-157922 Publication

Since solder has a large linear expansion coefficient, cracks may be formed in the first substrate due to thermal stress, or the annular metal layer may peel off from the first substrate.

The present invention was made in view of the above problems, and an object of the present invention is to suppress deterioration caused by thermal stress.

The present invention includes: a first substrate having a first surface; a second substrate mounted on the first substrate such that a second surface faces the first surface with a gap therebetween; an annular metal layer provided so as to surround a second substrate; and an annular metal layer provided in a region of the surface of the annular metal layer opposite to the first substrate on the center side of the first substrate in contact with the surface. an annular insulating layer, an acoustic wave element provided on at least one of the first surface and the second surface, surrounding the second substrate, sealing the acoustic wave element in the gap, and enclosing the annular metal layer. A sealing solder layer that is directly bonded to a surface of the annular metal layer on the opposite side of the first substrate and on which the annular insulating layer is not provided, and that is not directly bonded to the annular insulating layer. It is a wave device.

In the above configuration, the first substrate includes a support substrate and a piezoelectric substrate directly or indirectly bonded to the support substrate, and the acoustic wave element is a first acoustic wave element provided on the first surface. It is possible to have a configuration including.

In the above configuration, the annular metal layer surrounds the second substrate, is provided in a region on the support substrate where the piezoelectric substrate is not provided, and has a first annular metal layer whose side surface is in contact with the side surface of the piezoelectric substrate. a metal layer surrounding the second substrate and provided on the first annular metal layer, the inner periphery of which substantially coincides with the inner periphery of the first annular metal layer, or the inner periphery of the first annular metal layer that is closer to the inner periphery of the first annular metal layer; a second annular metal layer located on the piezoelectric substrate on the center side of one substrate, and the annular insulating layer is provided in contact with a surface of the second annular metal layer on the opposite side to the first substrate. , the outer periphery of the annular insulating layer is located closer to the outer periphery of the first substrate than the inner periphery of the first annular metal layer, and the sealing solder layer is located on the second annular metal layer on which the annular insulating layer is not provided. It can be configured to be directly bonded to the surface of the layer.

The present invention includes: a first substrate having a first surface; a second substrate mounted on the first substrate such that a second surface faces the first surface with a gap therebetween; an annular metal layer provided so as to surround a second substrate; an annular insulating layer provided on a region of the annular metal layer on the center side of the first substrate; surrounding an acoustic wave element provided on at least one side and the second substrate, sealing the acoustic wave element in the gap, and bonding to the surface of the annular metal layer on which the annular insulating layer is not provided; a sealing solder layer not bonded to the annular insulating layer, the first substrate includes a support substrate and a piezoelectric substrate directly or indirectly bonded to the support substrate, and the acoustic wave element The annular metal layer includes a first acoustic wave element provided on the first surface, the annular metal layer surrounds the second substrate, is provided on the support substrate in an area where the piezoelectric substrate is not provided, and is provided on the side surface. is provided on the first annular metal layer surrounding the first annular metal layer in contact with the side surface of the piezoelectric substrate and the second substrate, and the inner periphery is closer to the first annular metal layer than the inner periphery of the first annular metal layer. a second annular metal layer located on the outer peripheral side of the substrate, the inner periphery of the annular insulating layer substantially coincides with the inner periphery of the first annular metal layer, or the inner periphery of the first annular metal layer is closer to the first annular metal layer; The outer periphery of the annular insulating layer is located closer to the outer periphery of the first substrate than the inner periphery of the first annular metal layer, and the sealing solder layer is located on the center side of the first substrate. This is an acoustic wave device that connects to the surface of the second annular metal layer that is not covered.

In the above structure, the first annular metal layer may not be exposed between the second annular metal layer and the annular insulating layer.

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

In the above configuration, the first substrate may be a ceramic substrate, and the acoustic wave element may be provided on the second surface.

In the above structure, the linear expansion coefficient of the sealing solder layer may be larger than that of the first substrate.

In the above structure, the entire surface of the annular insulating layer opposite to the first substrate may be exposed to the gap .

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

The present invention includes a step of forming an annular metal layer on a first surface of a first substrate, and an annular insulating layer formed on an inner region of a surface of the annular metal layer opposite to the first substrate in contact with the surface. a step of mounting a second substrate on the first surface of the first substrate such that the second surface faces each other with a gap therebetween; an acoustic wave element provided on at least one of the surfaces is sealed in the void, and a surface of the annular metal layer on which the annular insulating layer is not provided among the surfaces of the annular metal layer opposite to the first substrate; This is a method for manufacturing an acoustic wave device, including the step of forming a sealing solder layer that is directly bonded to the annular insulating layer and not directly bonded to the annular insulating layer.

According to the present invention, deterioration caused by thermal stress can be suppressed.

FIG. 1(a) is a cross-sectional view of the acoustic wave device according to Example 1, FIG. 1(b) is an enlarged view of the vicinity of the annular metal layer, and FIG. 1(c) 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. 4A to 4D are cross-sectional views (part 2) showing the method for manufacturing the acoustic wave device according to the first embodiment. FIGS. 5A and 5B 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. FIGS. 7(a) to 7(c) are cross-sectional views of the vicinity of the annular metal layer of samples A to C in which simulations were performed. FIG. 8(a) is a cross-sectional view of an acoustic wave device according to Modification Example 1 of Example 1, FIG. 8(b) is an enlarged view of the vicinity of the annular metal layer, and FIG. 8(c) is a plan view. FIG. 9(a) is a cross-sectional view of the acoustic wave device according to Example 2, and FIG. 9(b) is an enlarged view of the vicinity of the annular metal layer. 10(a) is a circuit diagram of a filter according to a third embodiment, and FIG. 10(b) is a circuit diagram of a duplexer according to a first modification of the third embodiment.

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

FIG. 1(a) is a cross-sectional view of the acoustic wave device according to Example 1, FIG. 1(b) is an enlarged view of the vicinity of the annular metal layer, and FIG. 1(c) is a plan view. FIG. 1(c) illustrates the substrate 10, the annular metal layers 32, 34, and the annular insulating layer 15.

As shown in FIGS. 1(a) to 1(c), 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. In this way, the piezoelectric substrate 10b is directly or indirectly bonded onto 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. The side surface of the annular metal layer 32 is in contact with the side surface of the piezoelectric substrate 10b. The internal angle between the top surface and the side surface of the annular metal layer 32 may be an acute angle, a right angle, or an obtuse angle. 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 solder layer 30 and the annular metal layer 32. The gold layer has good wettability with the sealing solder layer 30 and joins the sealing solder layer 30 to the annular metal layer 34. An inner periphery 56 of the annular metal layer 34 is located inside the annular metal layer 32 (on the center side of the substrate 10).

The annular insulating layer 15 is provided on the inner region of the upper surface of the annular metal layer 34 and on the side surfaces of the annular metal layer 34 . The annular insulating layer 15 may not be provided on the side surface of the annular metal layer 34. The annular insulating layer 15 is, for example, a silicon oxide film, a silicon nitride film, an aluminum oxide film, or a resin film. The outer periphery 58 of the annular insulating layer 15 is located outside the inner periphery 54 of the annular metal layer 32 (on the outer periphery side of the substrate 10). The inner circumference 59 of the annular insulating layer 15 substantially coincides with the inner circumference 56 of the annular metal layer 34 . The inner periphery 59 of the annular insulating layer 15 may be located inside the inner periphery 56 of 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 solder layer 30 is provided on the substrate 10 so as to surround the substrate 20. The sealing solder layer 30 is, for example, solder containing tin. Since the sealing solder layer 30 is bonded to the upper surface of the annular metal layer 34 and not to the upper surface of the annular insulating layer 15, the inner circumference 57 of the sealing solder layer 30 substantially coincides with the outer circumference 58 of the annular insulating layer 15. A flat lid 36 is provided on the upper surface of the substrate 20 and the upper surface of the sealing solder 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 solder 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 solder 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 thickness of the annular insulating layer 15 is, for example, 0.1 μm to 5 μm. The width of the annular metal layer 32 is, for example, 25 μm to 100 μm. The distance D1 between the inner periphery 54 of the annular metal layer 32 and the inner periphery 56 of the annular metal layer 34 is, for example, 1 μm to 10 μm. The distance D2 between the inner periphery 54 of the annular metal layer 32 and the outer periphery 58 of the annular insulating layer 15 is, for example, 1 μm to 10 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.

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(b) are cross-sectional views showing a method of manufacturing an acoustic wave device according to Example 1. FIG. 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. 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(c), 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. 3(d), a metal layer 31 is formed on the support substrate 10a and the piezoelectric substrate 10b using, for example, a plating method. The metal layer 31 is, for example, a copper layer. Metal layer 31 may be formed on the seed layer.

As shown in FIG. 4A, 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 top surface of the annular metal layer 32 is substantially the same plane as the top surface of the piezoelectric substrate 10b.

As shown in FIG. 4(b), an acoustic wave element 12 is formed on a piezoelectric substrate 10b. Wiring 14 is formed on piezoelectric substrate 10b and via wiring 16. As shown in FIG. 4C, an annular metal layer 34 is formed on the annular metal layer 32. As shown in FIG. The annular metal layer 34 is formed using, for example, a sputtering method, a vacuum evaporation method, a CVD (Chemical Vapor Deposition) method, an etching method, or a lift-off method. As shown in FIG. 4(d), an annular insulating layer 15 is formed on the annular metal layer 34. As shown in FIG. The annular insulating layer 15 is formed using, for example, a sputtering method, a vacuum evaporation method, a CVD (Chemical Vapor Deposition) method, an etching method, or a lift-off method.

As shown in FIG. 5A, the substrate 20 is flip-chip mounted onto the substrate 10 via bumps 28. As a result, the acoustic wave elements 12 and 22 face each other with the air gap 26 in between. As shown in FIG. 5(b), a lid 36 having a solder plate made of, for example, tin and silver formed on its lower surface is placed on the substrate 20. The solder is heated and melted, and the lid 36 is pressed toward the substrate 20. As a result, since the upper surface of the annular metal layer 34 has good wettability with solder, the molten solder is bonded to the upper surface of the annular metal layer 34 . Since the solder has poor wettability with the annular insulating layer 15, the solder does not bond to the annular insulating layer 15. As a result, a sealing solder layer 30 that surrounds the substrate 20 and is bonded to the annular metal layer 34 is formed.

Thereafter, 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 solder layer 30 and the lid 36 is formed. As a result, the acoustic wave devices shown in FIGS. 1(a) to 1(c) 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. 6(a), in the acoustic wave device of Comparative Example 1, the annular insulating layer 15 is not provided on the annular metal layer 34, and the sealing solder layer 30 is bonded to the upper surface of the annular metal layer 34. has been done. The annular metal layer 32 is provided to improve heat dissipation from the sealing solder layer 30 to the support substrate 10a. The annular metal layer 34 is a layer for bonding with the sealing solder layer 30. In order to prevent the annular metal layer 32 from being exposed from the annular metal layer 34, the inner periphery 56 of the annular metal layer 34 is located inside the annular metal layer 32 from the viewpoint of alignment margin with the sealing solder layer 30.

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 solder layer 30 is a tin-silver layer. As shown in FIG. 6(b), a crack 55 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 solder layer 30, the linear expansion coefficient of the sealing solder 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 when thermal stress is applied to the piezoelectric substrate 10b, deterioration such as the formation of cracks 55 occurs.

[simulation]
In Comparative Example 1, the stress applied to the piezoelectric substrate 10b was simulated using the finite element method. FIGS. 7(a) to 7(c) are cross-sectional views of the vicinity of the annular metal layer of samples A to C in which simulations were performed. As shown in FIG. 7A, in sample A, the inner periphery 56 of the annular metal layer 34 is located inside the inner periphery 54 of the annular metal layer 32. The distance between the inner circumferences 54 and 56 is D1. The sealing solder layer 30 is bonded to the entire upper surface of the annular metal layer 34. The inner periphery 57 of the region where the sealing solder layer 30 is bonded to the annular metal layer 34 substantially coincides with the inner periphery 56 of the annular metal layer 34 .

As shown in FIG. 7B, in sample B, the inner periphery 57 of the region where the sealing solder layer 30 is bonded to the annular metal layer 34 substantially coincides with the inner periphery 54 of the annular metal layer 32 . As shown in FIG. 7C, in sample C, the inner periphery 57 of the region where the sealing solder layer 30 is bonded to the annular metal layer 34 is located outside the inner periphery 54 of the annular metal layer 32. The distance between the inner circumferences 54 and 57 is D2.

The simulation conditions are as follows.
Support substrate 10a: Sapphire substrate with a thickness of 75 μm Size of support substrate 10a: 1.2 mm x 1.1 mm
Piezoelectric substrate 10b: 42° rotated Y-cut, Interior angle θ: 57°
Annular metal layer 34: Nickel layer with a thickness of 2.5 μm Sealing solder layer 30: Sn-3.5Ag
Distance D1: 4μm
Distance D2: 4μm

The sealing solder layer 30 was formed at 250°C, and the stress applied to the piezoelectric substrate 10b when the temperature was lowered to 25°C was simulated. The stress is highest near the inner periphery 56 of the annular metal layer 34. The maximum stress applied to the piezoelectric substrate 10b is as follows.
Sample A: 1.04×10 ⁹ Pa
Sample B: 5.59×10 ⁸ Pa
Sample C: 3.27×10 ⁸ Pa
Sample B has a smaller maximum stress than sample A, and sample C has an even smaller maximum stress than sample B.

Therefore, it is conceivable that the inner periphery 56 of the annular metal layer 34 is aligned with or located outside the inner periphery 54 of the annular metal layer 32. However, if the inner periphery 56 of the annular metal layer 34 is located outside the inner periphery 54 of the annular metal layer 32, the upper surface of the annular metal layer 32 will be exposed. Even if the solder wettability of the annular metal layer 32 is poor, it is conceivable that a part of the sealing solder layer 30 may be bonded onto the annular metal layer 32. Furthermore, if the annular metal layer 32 is made of copper, it may become a contaminant in subsequent steps.

Therefore, as in Example 1, the annular insulating layer 15 is provided on the upper surface of the annular metal layer 34. Thereby, the sealing solder layer 30 is not bonded to the annular insulating layer 15, so that stress applied to the piezoelectric substrate 10b can be suppressed. Therefore, cracks and the like can be suppressed.

[Modification 1 of Example 1]
FIG. 8(a) is a cross-sectional view of an acoustic wave device according to Modification Example 1 of Example 1, FIG. 8(b) is an enlarged view of the vicinity of the annular metal layer, and FIG. 8(c) is a plan view. FIG. 8(c) illustrates the substrate 10, the annular metal layers 32 and 34, and the annular insulating layer 15. As shown in FIGS. 8(a) to 8(c), the inner periphery 56 of the annular metal layer 34 is located outside the inner periphery 54 of the annular metal layer 32. As shown in FIGS. The outer periphery 58 of the annular insulating layer 15 substantially matches the inner periphery 56 of the annular metal layer 34 , and the inner periphery 59 substantially matches the inner periphery 54 of the annular metal layer 32 or is located inside the inner periphery 54 . The inner circumference 57 of the sealing solder layer 30 substantially coincides with the inner circumference 56 of the annular metal layer 34 .

As in the first modification of the first embodiment, the annular metal layer 34 may not be provided in the region where the annular insulating layer 15 is provided. The outer periphery 58 of the annular insulating layer 15 may be located inside the inner periphery 56 of the annular metal layer 34, but from the viewpoint of not exposing the annular metal layer 32, the outer periphery 58 of the annular insulating layer 15 is located inside the inner periphery of the annular metal layer 34. 56 or located outside the inner periphery 56 is preferable. The inner periphery 59 of the annular insulating layer 15 may substantially match the inner periphery 54 of the annular metal layer 32, but in order to prevent the annular metal layer 32 from being exposed due to misalignment, the inner periphery 59 of the annular insulating layer 15 is preferably located inside the inner periphery 54 of the annular metal layer 32.

FIG. 9(a) is a cross-sectional view of the acoustic wave device according to Example 2, and FIG. 9(b) is an enlarged view of the vicinity of the annular metal layer. As shown in FIGS. 9A and 9B, the substrate 11 includes a plurality of stacked insulating layers 11a to 11c. The insulating layers 11a to 11c are, for example, ceramic layers such as LTCC (Low Temperature Co-fired Ceramics) or HTCC (High Temperature Co-fired Ceramics), or resin layers such as glass epoxy resin. The wiring 14 and the terminal 18 are connected by an internal wiring 16a. Internal wiring 16a includes via wiring that penetrates insulating layers 11a to 11c and interlayer wiring provided between insulating layers 11a to 11c.

The annular metal layer 32 is provided on the upper surface of the substrate 10. The annular metal layer 32 includes a low resistance layer 32a such as a copper layer, and a bonding layer 32b which has a higher resistance than the low resistance layer 32a and has better wettability with solder. The low resistance layer 32a and the bonding layer 32b are, for example, a copper layer and a nickel layer, respectively. An annular insulating layer 15 is provided from the inner region of the upper surface of the annular metal layer 32 to the upper surface of the substrate 10 . The annular insulating layer 15 is made of glass, for example. The annular insulating layer 15 may be made of a resin layer such as a silicone resin or a ceramic material such as LTCC or HTCC other than glass. The outer periphery 58 of the annular insulating layer 15 is located outside the inner periphery 54 of the annular metal layer 32, and the inner periphery 59 of the annular insulating layer 15 is located inside the inner periphery 54. The thickness of the low resistance layer 32a is, for example, 10 μm to 30 μm, the thickness of the bonding layer 32b is, for example, 2 μm to 10 μm, and the thickness and width of the annular insulating layer 15 are, for example, 20 μm to 50 μm and 80 μm to 120 μm, respectively. A plurality of substrates 20 are mounted on the substrate 10. The other configurations are the same as those in Example 1, and their explanation will be omitted.

When the substrate 10 is an insulator as in the second embodiment. There is a low possibility that cracks will occur in the piezoelectric substrate 10b as in the first embodiment. However, if thermal stress due to the difference in linear expansion coefficient between the sealing solder layer 30 and the substrate 10 is applied near the inner periphery 54 of the annular metal layer 32, the annular metal layer 32 may peel off from the substrate 10. In particular, when the low resistance layer 32a is a copper layer and the substrate 10 is an LTCC substrate, the annular metal layer 32 is likely to peel off from the substrate 10. Therefore, an annular insulating layer 15 is provided. Thereby, the thermal stress applied near the inner periphery 54 of the annular metal layer 32 is reduced, and peeling of the annular metal layer 32 can be suppressed.

According to Examples 1 and 2 and their modifications, the substrate 20 (second substrate) is placed on the substrate 10 (first substrate) such that the lower surface (second surface) is the upper surface (second surface) of the substrate 10 (first substrate). 1) so as to face each other with a gap 26 in between. The annular metal layers 32 and 34 are provided on the upper surface of the substrate 10 so as to surround the substrate 20. The annular insulating layer 15 is provided on the annular metal layers 32 and 34 in a region closer to the center of the substrate 10 . Acoustic wave elements 12 and 22 are provided on at least one of the upper surface of substrate 10 and the lower surface of substrate 20. The sealing solder layer 30 surrounds the substrate 20, seals the acoustic wave elements 12 and 22 in the gap 26, joins the surfaces of the annular metal layers 32 and 34 on which the annular insulating layer 15 is not provided, and connects the annular insulating layer 15 to the surfaces of the annular metal layers 32 and 34. It is not connected to 15. Thereby, cracks in the piezoelectric substrate 10b can be suppressed as in the first embodiment and its modification. Further, as in the second embodiment, peeling of the annular metal layer 32 from the substrate 10 can be suppressed. In this way, deterioration of the acoustic wave device due to thermal stress can be suppressed.

As in the first embodiment and its modifications, the substrate 10 includes a support substrate 10a and a piezoelectric substrate 10b directly or indirectly bonded to the support substrate 10a, and includes an acoustic wave element 12 (first acoustic wave element). is provided on the upper surface of the substrate 10. In such a configuration, cracks are likely to occur in the piezoelectric substrate 10b due to thermal stress. Therefore, it is preferable to provide the annular insulating layer 15.

In FIG. 6A of Comparative Example 1, the annular metal layer 32 (first annular metal layer) surrounds the substrate 20, is provided on the support substrate 10a in an area where the piezoelectric substrate 10b is not provided, and is provided on the side surface. is in contact with the side surface of the piezoelectric substrate 10b. The annular metal layer 34 (second annular metal layer) surrounds the substrate 20 and is provided on the annular metal layer 32. The inner periphery 56 of the annular metal layer 34 substantially coincides with the inner periphery 54 of the annular metal layer 32 or is located on the piezoelectric substrate 10b closer to the center of the substrate 10 than the inner periphery 54. In such a structure, the sealing solder layer 30 is bonded to the entire upper surface of the annular metal layer 34. As a result, a crack 55 is generated in the piezoelectric substrate 10b, as shown in FIG. 6(b).

Therefore, according to the first embodiment, the annular insulating layer 15 is provided on the annular metal layer 34 , and the outer periphery 58 of the annular insulating layer 15 is located closer to the outer periphery of the substrate 10 than the inner periphery 54 of the annular metal layer 32 . The sealing solder layer 30 is bonded to the surface of the annular metal layer 34 on which the annular insulating layer 15 is not provided. This reduces the thermal stress on the inner periphery 56 of the annular metal layer 34 and suppresses cracks in the piezoelectric substrate 10b, as in the simulated sample C.

Note that when the inner side surfaces of the annular metal layers 32 and 34 are inclined or curved, the inner periphery 56 of the annular metal layer 34 is located closer to the center of the substrate 10 than the inner periphery 54 of the annular metal layer 32. At least a portion of the inner side surface of the metal layer 34 may be located closer to the center of the substrate 10 than at least a portion of the inner side surface of the annular metal layer 32 . In addition, the inner periphery 56 of the annular metal layer 34 substantially coincides with the inner periphery 54 of the annular metal layer 32 means that the position of at least a portion of the inner side surface of the annular metal layer 34 is at least the inner periphery 54 of the annular metal layer 32 . It is only necessary that they match to the extent that some position and manufacturing errors are allowed. The same applies to the inner periphery and outer periphery of other components.

In the first modification of the first embodiment, the inner periphery 56 of the annular metal layer 34 is located closer to the outer periphery of the substrate 10 than the inner periphery 54 of the annular metal layer 32 . In this case, the sealing solder layer 30 may be bonded to the upper surface of the annular metal layer 32 that is not covered by the annular metal layer 34, or the annular metal layer 32 may cause contamination.

Therefore, the annular insulating layer 15 is provided, and the inner periphery 59 of the annular insulating layer 15 substantially coincides with the inner periphery 54 of the annular metal layer 32 or is located closer to the center of the substrate 10 than the inner periphery 54, and the outer periphery 59 of the annular insulating layer 15 is located closer to the outer circumference of the substrate 10 than the inner circumference 54 of the annular metal layer 32 . The sealing solder layer 30 is bonded to the surface of the annular metal layer 34 on which the annular insulating layer 15 is not provided. By providing the annular insulating layer 15 in this way, it is possible to prevent the sealing solder layer 30 from bonding to the upper surface of the annular metal layer 32 and to prevent the annular metal layer 32 from causing contamination. Moreover, cracks in the piezoelectric substrate 10b can be suppressed.

It is preferable that the annular metal layer 32 is not exposed between the annular metal layer 34 and the annular insulating layer 15. This can further prevent the sealing solder layer 30 from bonding to the upper surface of the annular metal layer 32 and the annular metal layer 32 from causing contamination.

In Example 1 and its modifications, when the piezoelectric substrate 10b is a lithium tantalate substrate or a lithium niobate substrate, the piezoelectric substrate 10b is brittle and easily cracks. Therefore, it is preferable to provide the annular insulating layer 15.

As in the second embodiment, the substrate 10 may be a ceramic substrate, and the acoustic wave element 22 may be provided on the lower surface of the substrate 20. Thereby, peeling of the annular metal layer 32 can be suppressed.

When the coefficient of linear expansion of the sealing solder layer 30 is larger than that of the substrate 10, thermal stress is likely to be applied near the inner periphery of the annular metal layers 32 and 34. Therefore, it is preferable to provide the annular insulating layer 15. When the sealing solder layer 30 contains tin, as shown in Table 1, the coefficient of linear expansion becomes as high as about 30 ppm/°C. Therefore, it is preferable to provide the annular insulating layer 15.

The annular metal layers 32, 34 and the annular insulating layer 15 do not have to completely surround the substrate 20. That is, the annular metal layers 32 and 34 and the annular insulating layer 15 may be provided in at least a portion surrounding the substrate 20.

In the first and second embodiments and their 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. .

FIG. 10(a) is a circuit diagram of a filter according to the third embodiment. As shown in FIG. 10(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 third 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. 10(b) is a circuit diagram of a duplexer according to Modification 1 of Embodiment 3. As shown in FIG. 10(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 third 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 Annular insulating layer 16 Via wiring 18 Terminal 20 Substrate 26 Gap 28 Bump 30 Sealing solder layer 32, 34 Annular metal layer 36 Lid 50 Transmission filter 52 Reception filter 54, 56, 57, 59 Inner circumference 58 Outer circumference

Claims (11)

a first substrate having a first surface;
a second substrate mounted on the first substrate so that a second surface faces the first surface with a gap therebetween;
an annular metal layer provided on the first surface so as to surround the second substrate;
an annular insulating layer provided in a region on the center side of the first substrate among the surfaces of the annular metal layer opposite to the first substrate in contact with the surface ;
an acoustic wave element provided on at least one of the first surface and the second surface;
A surface of the annular metal layer that surrounds the second substrate, seals the acoustic wave element in the gap, and is not provided with the annular insulating layer among the surfaces of the annular metal layer on the opposite side from the first substrate. a sealing solder layer that is directly bonded to the annular insulating layer and not directly bonded to the annular insulating layer;
An elastic wave device equipped with The first substrate includes a support substrate and a piezoelectric substrate directly or indirectly bonded to the support substrate, and the acoustic wave element includes a first acoustic wave element provided on the first surface. 1. The elastic wave device according to 1. The annular metal layer is
a first annular metal layer surrounding the second substrate, provided on the supporting substrate in a region where the piezoelectric substrate is not provided, and having a side surface in contact with a side surface of the piezoelectric substrate;
Surrounding the second substrate, provided on the first annular metal layer, the inner periphery of which substantially coincides with the inner periphery of the first annular metal layer, or closer to the center of the first substrate than the inner periphery of the first annular metal layer. a second annular metal layer located on the piezoelectric substrate on the side;
The annular insulating layer is provided in contact with a surface of the second annular metal layer opposite to the first substrate , and the outer periphery of the annular insulating layer is closer to the first substrate than the inner periphery of the first annular metal layer. Located on the outer periphery,
The acoustic wave device according to claim 2, wherein the sealing solder layer is directly bonded to a surface of the second annular metal layer on which the annular insulating layer is not provided. a first substrate having a first surface;
a second substrate mounted on the first substrate so that a second surface faces the first surface with a gap therebetween;
an annular metal layer provided on the first surface so as to surround the second substrate;
an annular insulating layer provided on the annular metal layer in a region closer to the center of the first substrate;
an acoustic wave element provided on at least one of the first surface and the second surface;
a sealing solder that surrounds the second substrate, seals the acoustic wave element in the gap, is bonded to the surface of the annular metal layer on which the annular insulating layer is not provided, and is not bonded to the annular insulating layer; layer and
Equipped with
The first substrate includes a support substrate and a piezoelectric substrate directly or indirectly bonded to the support substrate, and the acoustic wave element includes a first acoustic wave element provided on the first surface,
The annular metal layer is
a first annular metal layer surrounding the second substrate, provided on the supporting substrate in a region where the piezoelectric substrate is not provided, and having a side surface in contact with a side surface of the piezoelectric substrate;
a second annular metal layer surrounding the second substrate, provided on the first annular metal layer, and having an inner periphery located closer to the outer periphery of the first substrate than the inner periphery of the first annular metal layer; ,
The inner periphery of the annular insulating layer substantially coincides with the inner periphery of the first annular metal layer or is located closer to the center of the first substrate than the inner periphery of the first annular metal layer, and the outer periphery of the annular insulating layer located closer to the outer circumference of the first substrate than the inner circumference of the first annular metal layer,
The sealing solder layer is an acoustic wave device that is bonded to the surface of the second annular metal layer on which the annular insulating layer is not provided. The acoustic wave device according to claim 4, wherein the first annular metal layer is not exposed between the second annular metal layer and the annular insulating layer. The acoustic wave device according to any one of claims 2 to 5, wherein the piezoelectric substrate is a lithium tantalate substrate or a lithium niobate substrate. The first substrate is a ceramic substrate,
The acoustic wave device according to claim 1, wherein the acoustic wave element is provided on the second surface. The acoustic wave device according to any one of claims 1 to 7, wherein the linear expansion coefficient of the sealing solder layer is larger than that of the first substrate. The acoustic wave device according to any one of claims 1 to 8, wherein the entire surface of the annular insulating layer opposite to the first substrate is exposed to the void. A filter comprising the elastic wave device according to any one of claims 1 to 9 . forming an annular metal layer on the first surface of the first substrate;
forming an annular insulating layer on an inner region of the surface of the annular metal layer on the side opposite to the first substrate in contact with the surface ;
mounting a second substrate on the first surface of the first substrate so that the second surface faces the first surface with a gap therebetween;
an acoustic wave element surrounding the second substrate and provided on at least one of the first surface and the second surface is sealed in the gap; forming a sealing solder layer that is directly bonded to the surface of the annular metal layer on which the annular insulating layer is not provided, and that is not directly bonded to the annular insulating layer;
A method of manufacturing an acoustic wave device including:

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