Elastic wave device and communication module

Abstract

To provide an acoustic wave device which suppresses characteristic deterioration with an enhanced electromagnetic shield effect.SOLUTION: An acoustic wave device 100 includes: a substrate 10 having a top face 13, a bottom face 14 opposite to the top face 13 and a plurality of side faces 15 connecting the top face 13 with the bottom face 14; an acoustic wave element 16 provided on the top face 13 of the substrate 10; a substrate 20 provided on the acoustic wave element 16 on the top face 13 of the substrate 10 with a gap 82 between itself and the substrate 10; an acoustic wave element 26 provided on the substrate 20; a ground terminal 44 provided on the bottom face 14 of the substrate 10; a shield metal layer 70 provided between the acoustic wave element 16 and the acoustic wave element 26 and positioned in the gap 82; and a coating metal layer 75 provided to cover more than half the region of the plurality of side faces 15 of the substrate 10 to electrically connect the shield metal layer 70 with the ground terminal 44.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an elastic wave device and a communication module.

Background Art

[0002] It is known to obtain an electromagnetic shielding effect by providing a metal layer connected to ground on a surface opposite to the surface on which an elastic wave element of an elastic wave device is provided (for example, Patent Document 1). Further, in order to miniaturize an elastic wave device, it is known to mount a second substrate provided with a second elastic wave element on a first substrate provided with a first elastic wave element. In this case, it is known to provide a metal layer connected to ground between the first elastic wave element and the second elastic wave element for electromagnetic shielding (for example, Patent Documents 2 and 3).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, merely providing a metal layer connected to ground between the first elastic wave element and the second elastic wave element may result in an insufficient electromagnetic shielding effect and degradation of characteristics.

[0005] The present invention has been made in view of the above problems, and an object thereof is to enhance the electromagnetic shielding effect and suppress degradation of characteristics.

Means for Solving the Problems

[0006] The present invention relates to a first substrate having a first surface, a second surface opposite to the first surface, and a plurality of side surfaces connecting the first surface and the second surface, a first elastic wave element provided on the first surface of the first substrate, a second substrate provided on the first elastic wave element on the first surface of the first substrate and having a gap with the first substrate, a second elastic wave element provided on the second substrate, a ground terminal provided on the second surface of the first substrate, An annular metal layer provided on the first surface of the first substrate to surround the first elastic wave element and having a rectangular shape in plan view for sealing the first elastic wave element in the gap between the first substrate and the second substrate; provided between the first elastic wave element and the second elastic wave element and located within the gap and, on all sides of the annular metal layer, connecting to the annular metal layer; a first metal layer, and the first substrate provided over the side surfaces of all sides of the annular metal layer from all of the plurality of side surfaces; covering more than half of the regions of the plurality of side surfaces yes , and a second metal layer for electrically connecting the first metal layer and the ground terminal. The elastic wave device comprises:

[0007] In the above configuration, the second metal layer may be configured to extend from the end on the first surface side to the end on the second surface side across the plurality of side surfaces of the first substrate. in each of them; from the end on the first surface side to the end on the second surface side being provided; It can be configured as such.

[0008] In the above configuration, The second metal layer is provided from all of the plurality of side surfaces of the first substrate over the second surface and is connected to the plurality of ground terminals; It can be configured as such.

[0009] In the above configuration, the second metal layer may be configured to cover 90% or more of the regions of the plurality of side surfaces of the first substrate.

[0010] In the above configuration, The annular metal layer includes a part of the first metal layer; the second metal layer may be configured to be provided from all of the plurality of side surfaces of the first substrate over the part; It can be configured as such.

[0011] In the above configuration, the second substrate has a third surface facing the first substrate, a fourth surface opposite to the third surface, and a plurality of side surfaces connecting the third surface and the fourth surface. The second elastic wave element is provided on the third surface and is sealed within the gap together with the first elastic wave element by the annular metal layer. The second metal layer is provided from the plurality of side surfaces of the first substrate all of; to the side surface;Via the plurality of side surfaces of the second substrate all of; And it can be configured to cover over the fourth surface.

[0012] In the above configuration, a sealing portion provided on a fourth surface opposite to a third surface of the second substrate facing the first surface of the first substrate is provided. The second elastic wave element is provided on the fourth surface, and is sealed in a space different from the space between the second substrate and the sealing portion by the sealing portion. The second metal layer covers from the plurality of side surfaces of the first substrate all of; To a plurality of side surfaces connecting the third surface and the fourth surface via the annular metal layer side surface; And it can be configured to cover over the surface of the sealing portion. all of; And it can be configured to cover over the surface of the sealing portion.

[0013] In the above configuration, A third metal layer provided on the first substrate and to which the annular metal layer is joined; The first substrate penetrates from the first surface to the second surface, the third metal layer; And wiring for electrically connecting to the ground terminal via; Wiring and; It can be further configured to include.

[0014] In the above configuration, a first elastic wave filter is configured by a plurality of the first elastic wave elements provided on the first substrate, and a second elastic wave filter having a pass band different from that of the first elastic wave filter is configured by a plurality of the second elastic wave elements provided on the second substrate. A multiplexer can be configured to include the first elastic wave filter and the second elastic wave filter.

[0015] The present invention is a communication module including a circuit board and the elastic wave; Device described above mounted on the circuit board.

Advantages of the Invention

[0016] According to the present invention, the electromagnetic shielding effect can be enhanced, and deterioration of characteristics can be suppressed.

Brief Description of the Drawings

[0017]

Figure 1

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Figure 17

BEST MODE FOR CARRYING OUT THE INVENTION

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

EXAMPLE

[0019] Fig. 1 is a cross-sectional view of the surface acoustic wave device according to Example 1. As shown in Fig. 1, in the surface acoustic wave device 100 of Example 1, a substrate 20 provided with a surface acoustic wave element 26 is mounted on a substrate 10 provided with a surface acoustic wave element 16. The substrate 10 is formed of an insulating member and includes a support substrate 11 and a piezoelectric layer 12. Similarly, the substrate 20 is formed of an insulating member and includes a support substrate 21 and a piezoelectric layer 22.

[0020] The support substrates 11 and 21 are, for example, a sapphire substrate, an alumina substrate, a spinel substrate, a quartz substrate, a quartz crystal substrate, a silicon substrate, a zirconium oxide substrate, or a resin substrate, and have a thickness of about 50 μm to 150 μm. The sapphire substrate is a single-crystalline substrate mainly composed of Al 2 O 3 The alumina substrate is a polycrystalline substrate mainly composed of Al 2 O 3 The spinel substrate is a single-crystalline or polycrystalline substrate mainly composed of MgAl 2 O 4 The quartz substrate is an amorphous substrate mainly composed of SiO 2 The quartz crystal substrate is a single-crystalline substrate mainly composed of SiO 2

[0021] The piezoelectric layers 12 and 22 are, for example, single crystal lithium tantalate layers or single crystal lithium niobate layers, and have a thickness of about 10 μm to 30 μm. It is preferable that the linear expansion coefficient of the support substrate 11 is smaller than that of the piezoelectric layer 12, and the linear expansion coefficient of the support substrate 21 is smaller than that of the piezoelectric layer 22. Thereby, the frequency temperature dependence can be reduced. Note that the substrate 10 is not limited to the case where the piezoelectric layer 12 is provided on the support substrate 11, and may be a single plate of lithium tantalate or lithium niobate. Similarly, the substrate 20 is not limited to the case where the piezoelectric layer 22 is provided on the support substrate 21, and may be a single plate of lithium tantalate or lithium niobate.

[0022] An insulating film having an acoustic impedance different from that of the support substrate and the piezoelectric layer may be provided between the support substrate 11 and the piezoelectric layer 12 and / or between the support substrate 21 and the piezoelectric layer 22 in order to improve the acoustic characteristics of the elastic wave element. In this way, the piezoelectric layer 12 is directly or indirectly bonded to the surface of the support substrate 11, and the piezoelectric layer 22 is directly or indirectly bonded to the surface of the support substrate 21. The insulating film having an acoustic impedance different from that of the support substrate and the piezoelectric layer has a temperature coefficient of elastic constant with a sign opposite to that of the temperature coefficient of elastic constant of the piezoelectric layer, and may be, for example, a silicon oxide layer without addition or containing an additive element such as fluorine. Thereby, the frequency temperature coefficient can be reduced. The insulating film having an acoustic impedance different from that of the support substrate and the piezoelectric layer is, for example, polycrystalline or amorphous, and may be, for example, an aluminum oxide layer, a silicon layer, an aluminum nitride layer, a silicon nitride layer, or a silicon carbide layer.

[0023] The elastic wave element 16 is provided on the upper surface 13 of the substrate 10. The elastic wave element 26 is provided on the lower surface 24 of the substrate 20. The upper surface 13 of the substrate 10 has irregularities due to the piezoelectric layer 12. Similarly, the lower surface 24 of the substrate 20 has irregularities due to the piezoelectric layer 22. The upper surface 13 of the substrate 10 and the lower surface 24 of the substrate 20 face each other with a gap 82 therebetween. Therefore, the elastic wave element 16 and the elastic wave element 26 face each other within the gap 82 between the substrate 10 and the substrate 20.

[0024] Figure 2 is a plan view of the elastic wave device in Example 1. In Figure 2, the elastic wave device 16 is shown as an example, and the same applies to the elastic wave device 26. As shown in Figure 2, the elastic wave device 16 is, for example, a surface acoustic wave resonator, and has an IDT (Interdigital Transducer) 30 and reflectors 34 on the piezoelectric layer 12. The IDT 30 has a pair of opposing comb-shaped electrodes 31. The comb-shaped electrode 31 has a plurality of electrode fingers 32 and a bus bar 33 to which the plurality of electrode fingers 32 are connected. The reflectors 34 are provided on both sides of the IDT 30. The IDT 30 excites surface acoustic waves in the piezoelectric layer 12. The reflectors 34 reflect the surface acoustic waves. The IDT 30 and the reflectors 34 are formed of a metal film such as an aluminum film or a copper film, for example.

[0025] In the elastic wave device 100 of Example 1, a transmission filter is formed by a plurality of elastic wave devices 16 provided on the piezoelectric layer 12, and a reception filter is formed by a plurality of elastic wave devices 26 provided on the piezoelectric layer 22. This will be described later.

[0026] As shown in Figure 1, on the upper surface 13 of the substrate 10, a wiring 17 electrically connected to the elastic wave device 16 is provided. On the lower surface 24 of the substrate 20, a wiring 27 electrically connected to the elastic wave device 26 is provided. The wirings 17 and 27 are metal layers including, for example, a copper layer, an aluminum layer, or a gold layer. On the lower surface 14 opposite to the upper surface 13 of the substrate 10, a plurality of terminals, which are foot pads for connecting the elastic wave device 100 to the outside, are provided. The plurality of terminals include a reception terminal 41 and a ground terminal 44. The terminals are metal layers including a copper layer, an aluminum layer, or a gold layer, and have a thickness of about several μm.

[0027] The surface acoustic wave device 16 provided on the upper surface 13 of the substrate 10 is electrically connected to the ground terminal 44 via the wiring 17 and the via wiring 54 provided in the substrate 10. The surface acoustic wave device 26 provided on the lower surface 24 of the substrate 20 is electrically connected to the reception terminal 41 via the wiring 27, the pillar 61 provided between the substrates 10 and 20, and the via wiring 51 provided in the substrate 10. The pillar 61 is joined to the metal layer 18 provided on the upper surface 13 of the substrate 10 and the wiring 27 provided on the lower surface 24 of the substrate 20 by solder.

[0028] An annular metal layer 60 surrounding the surface acoustic wave device 16 and the surface acoustic wave device 26 is provided between the substrate 10 and the substrate 20. Further, a shield metal layer 70 is provided in the gap 82 located between the surface acoustic wave device 16 and the surface acoustic wave device 26 between the substrate 10 and the substrate 20. The annular metal layer 60 includes a part 71 of the shield metal layer 70, and columnar portions 65a and 65b provided with the part 71 interposed therebetween. The columnar portion 65a is joined to the metal layer 18 provided on the upper surface 13 of the substrate 10 by solder, and the columnar portion 65b is joined to the metal layer 28 provided on the lower surface 24 of the substrate 20 by solder. The shield metal layer 70 preferably extends over the entire region where the surface acoustic wave device 16 and the surface acoustic wave device 26 are provided and is provided between the surface acoustic wave device 16 and the surface acoustic wave device 26. However, it may extend over 2 / 3 or more of the region where the surface acoustic wave device 16 and the surface acoustic wave device 26 are provided, or may extend over 3 / 4 or more of the region.

[0029] The elastic wave elements 16 and 26 are sealed in the gap 82 between the substrate 10 and the substrate 20 by the annular metal layer 60. The shield metal layer 70 is in contact with the annular metal layer 60 and is electrically connected thereto. An opening is provided in the shield metal layer 70, and the pillar 61 passes through the opening. An insulating resin film 72 is embedded between the pillar 61 and the shield metal layer 70. Thereby, the pillar 61 and the shield metal layer 70 are electrically insulated from each other. When a sufficient distance can be ensured between the shield metal layer 70 and the pillar 61, the resin film 72 may not be provided, and they may be insulated with the gap therebetween. In this case, the gap 82 between the substrate 10 and the shield metal layer 70 and the gap 82 between the substrate 20 and the shield metal layer 70 communicate with each other.

[0030] The columnar portions 65a and 65b are metal layers including, for example, a nickel layer, a copper layer, or a gold layer, and have a height of about 10 μm to 30 μm. The shield metal layer 70 is a metal layer including, for example, a conductive metal layer such as a copper layer, a gold layer, a silver layer, a tungsten layer, an aluminum layer, or a titanium layer, or a magnetic metal layer such as an iron layer, a nickel layer, or an iron-nickel alloy layer (such as a kovar layer). The thickness of the shield metal layer 70 is preferably equal to or greater than the skin depth of the electromagnetic wave to be shielded, and is, for example, about 1 μm to 40 μm.

[0031] FIG. 3(a) and FIG. 3(c) are plan views of the substrates in Example 1, and FIG. 3(b) is a plan view of the shield metal layer. FIG. 3(a) is a plan view of the substrate 20, and for easy understanding of the correspondence with FIGS. 3(b) and 3(c), it is a plan view seen through from above the substrate 20. FIG. 3(c) is a plan view of the substrate 10, and the terminals provided on the lower surface 14 of the substrate 10 are shown by dotted lines. Also, in FIG. 3(c), the illustration of the pillars 61 to 63 is omitted for clarity of the drawing.

[0032] As shown in FIG. 3(a), a plurality of surface acoustic wave elements 26, wirings 27, and pillars 61 to 63 are provided on the substrate 20 (the lower surface in FIG. 1). The plurality of surface acoustic wave elements 26 include series resonators S21 and S22 and a parallel resonator P21. The pillars 61 to 63 are connected to the wiring 27. The annular metal layer 60 is provided surrounding the series resonators S21 and S22, the parallel resonator P21, and the wiring 27. The pillars 61 to 63 are metal layers including, for example, a copper layer, a gold layer, a silver layer, a tungsten layer, an aluminum layer, a titanium layer, an iron layer, a nickel layer, or an iron-nickel alloy layer, and have substantially the same height as the annular metal layer 60.

[0033] As shown in FIG. 3(b), an insulating resin film 72 is provided between the shield metal layer 70 and the pillars 61 and 62, and the pillars 61 and 62 are electrically insulated from the shield metal layer 70. The pillar 63 is in contact with the shield metal layer 70 and is electrically connected thereto. The shield metal layer 70 is provided over the entire region where the substrates 10 and 20 face each other in plan view.

[0034] As shown in FIG. 3(c), a plurality of surface acoustic wave elements 16, wirings 17, and an annular metal layer 60 are provided on the substrate 10. The plurality of surface acoustic wave elements 16 include series resonators S11 and S12 and a parallel resonator P11. Via wirings 50 to 54 are provided in the substrate 10. The via wiring 50, the via wiring 52, and the via wiring 54 are connected to the wiring 17. The via wiring 51 is connected to the pillar 61, the via wiring 52 is connected to the pillar 62, and the via wiring 53 is connected to the pillar 63. The annular metal layer 60 is provided surrounding the series resonators S11 and S12, the parallel resonator P11, and the wiring 17. The via wirings 50 to 54 are metal layers including, for example, a copper layer, an aluminum layer, or a gold layer.

[0035] Via wiring 50 is connected to the transmission terminal 40, via wiring 52 is connected to the common terminal 42, and via wiring 54 is connected to the ground terminal 44. Therefore, the series resonators S11 and S12 are connected in series between the transmission terminal 40 and the common terminal 42. The parallel resonator P11 is connected in parallel between the transmission terminal 40 and the common terminal 42. The parallel resonator P11 is connected between the wiring 17 between the series resonator S11 and the series resonator S12 and the ground terminal 44. Thus, a transmission filter 19, which is a ladder-type filter, is provided on the substrate 10.

[0036] Via wiring 51 is connected to the reception terminal 41, via wiring 52 is connected to the common terminal 42, and via wiring 53 is connected to the ground terminal 43. Therefore, the series resonators S21 and S22 provided on the substrate 20 are connected in series between the common terminal 42 and the reception terminal 41. The parallel resonator P21 is connected in parallel between the common terminal 42 and the reception terminal 41. The parallel resonator P21 is connected between the wiring 27 between the series resonator S21 and the series resonator S22 and the ground terminal 43. Thus, a reception filter 29, which is a ladder-type filter, is provided on the substrate 20.

[0037] The transmission filter 19 passes the signal in the transmission band among the high-frequency signals input from the transmission terminal 40 as a transmission signal to the common terminal 42, and suppresses signals of other frequencies. The reception filter 29 passes the signal in the reception band among the high-frequency signals input from the common terminal 42 as a reception signal to the reception terminal 41, and suppresses signals of other frequencies. Thus, the surface acoustic wave device 100 is a duplexer. In addition, ground terminals 45 to 47 are also provided on the lower surface 14 of the substrate 10.

[0038] As shown in FIG. 1, a coating metal layer 75 is provided to cover an area that is more than half of the total area of a plurality of side surfaces 15 of a substrate 10. The side surface 15 is a surface that connects the upper surface 13 and the lower surface 14. The upper surface 13 and the lower surface 14 of the substrate 10 are substantially rectangular in a plan view, and the substrate 10 has four side surfaces 15. The coating metal layer 75 extends from the side surface 15 of the substrate 10 to the annular metal layer 60 and covers at least a part of the surface of the annular metal layer 60. In Example 1, an example where the coating metal layer 75 covers the entire surface of all the side surfaces 15 of the substrate 10, the entire outer surface of the annular metal layer 60, the entire surface of all the side surfaces 25 of the substrate 20, and the entire surface of the upper surface 23 of the substrate 20 is shown. The upper surface 23 of the substrate 20 is a surface opposite to the lower surface 24, and the side surface 25 is a surface that connects the upper surface 23 and the lower surface 24. The substrate 20 has four side surfaces 25.

[0039] The coating metal layer 75 is a single-layer film or a laminated film of a high-conductivity metal such as silver, copper, gold, or aluminum. The shield metal layer 70 may be formed of a non-magnetic material such as titanium or may be formed of a magnetic material such as iron or nickel. The thickness of the coating metal layer 75 is, for example, about 1 μm to 5 μm. From the viewpoint of giving the coating metal layer 75 an electromagnetic shielding effect, the thickness of the coating metal layer 75 is preferably not less than the skin depth of the electromagnetic wave to be shielded.

[0040] FIG. 4(a) is a perspective view of an elastic wave device showing the coating region of the coating metal layer in Example 1, and FIG. 4(b) is a plan view showing the lower surface of the substrate. In FIGS. 4(a) and 4(b), for clarity of the drawing, the region where the coating metal layer 75 is provided is hatched. Further, FIG. 4(b) is a plan view of the lower surface 14 seen through from above the substrate 10. As shown in FIG. 4(a), in Example 1, the coating metal layer 75 covers the entire surface of all the side surfaces 15 of the substrate 10, the entire outer surface of the annular metal layer 60, the entire surface of all the side surfaces 25 of the substrate 20, and the entire surface of the upper surface 23 of the substrate 20. As shown in FIG. 4(b), the coating metal layer 75 extends from the side surface 15 of the substrate 10 to the lower surface 14 and is in contact with the ground terminals 43 to 47. Therefore, the shield metal layer 70 is electrically connected to the ground via the coating metal layer 75.

[0041] [Manufacturing Method] Figs. 5(a) to 6(b) are cross-sectional views showing a method for manufacturing an elastic wave device according to Embodiment 1. In Figs. 5(a) to 6(a), it is manufactured in a wafer state, and a plurality of elastic wave devices are formed simultaneously, but here, for clarity of the drawing, only one elastic wave device is illustrated. As shown in Fig. 5(a), after forming via holes in the support substrate 11, via wirings 50 to 54 (only via wirings 51 and 54 are illustrated in Fig. 5(a)) are formed in the via holes. The via holes are formed, for example, by laser light irradiation or etching. The via wirings 50 to 54 are formed, for example, by an electrolytic plating method. Thereafter, after bonding a piezoelectric substrate to the surface of the support substrate 11, the piezoelectric substrate is thinned by polishing or grinding or the like to form a piezoelectric layer 12. For the bonding between the support substrate 11 and the piezoelectric substrate, for example, a direct bonding method by activating the surfaces of the support substrate 11 and the piezoelectric substrate and performing room temperature bonding is used. The substrate 10 is formed by the support substrate 11 and the piezoelectric layer 12.

[0042] Next, terminals 40 to 47 (only terminals 41 and 44 are illustrated in Fig. 5(a)) are formed on the lower surface 14 of the substrate 10. The piezoelectric layer 12 is etched to pattern the piezoelectric layer 12. An elastic wave element 16 is formed on the piezoelectric layer 12. A wiring 17 electrically connected to the elastic wave element 16 is formed. A metal layer 18 is formed at a location where the annular metal layer 60 and the pillars 61 to 63 are joined. As the formation methods of the elastic wave element 16, the wiring 17, the metal layer 18, and the terminals 40 to 47, generally known methods are used. Thus, the substrate 10 provided with the elastic wave element 16 and the like is formed.

[0043] As shown in FIG. 5(b), after bonding a piezoelectric substrate to the surface of the support substrate 21, the piezoelectric substrate is thinned by polishing, grinding, or the like to form a piezoelectric layer 22. For the bonding between the support substrate 21 and the piezoelectric substrate, for example, a direct bonding method by activating the surfaces of the support substrate 21 and the piezoelectric substrate and performing room temperature bonding is used. The substrate 20 is formed by the support substrate 21 and the piezoelectric layer 22. Next, the piezoelectric layer 22 is etched to pattern the piezoelectric layer 22. An elastic wave element 26 is formed on the piezoelectric layer 22. A wiring 27 electrically connected to the elastic wave element 26 is formed. A metal layer 28 is formed at the location where the annular metal layer 60 is bonded. Generally known methods are used for forming the elastic wave element 26, the wiring 27, and the metal layer 28. Thus, the substrate 20 provided with the elastic wave element 26 and the like is formed.

[0044] As shown in FIG. 5(c), after machining the outer shape of the metal foil 90 to be the same as that of the substrates 10 and 20, the metal foil 90 around the regions where the pillars 61 and 62 are formed is removed to form a donut-shaped opening. The opening is filled and cured with an insulating resin to form an insulating resin film 72. The width of the opening is, for example, 60 μm, and the diameter of the metal foil 90 in the inner region of the hollow circular opening is, for example, 120 μm. The removal of the metal foil 90 uses, for example, wet etching.

[0045] As shown in FIG. 5(d), metal layers are formed on both surfaces of the metal foil 90, for example, by electroforming. Thus, a shield metal layer 70 made of the metal foil 90, an annular metal layer 60 including a part 71 of the shield metal layer 70, the columnar parts 65a and 65b, and pillars 61 to 63 (only the pillar 61 is shown in FIG. 5(d)) including a part of the metal foil 90 are formed. The diameters of the pillars 61 to 63 and the width of the annular metal layer 60 are, for example, 100 μm. The pillars 61 to 63 and the annular metal layer 60 have a structure in which, for example, a copper layer with a thickness of 20 μm, a nickel layer with a thickness of 5 μm, and a tin layer with a thickness of 5 μm are laminated in order from the shield metal layer 70 side.

[0046] As shown in FIG. 6(a), pillars 61 to 63 and annular metal layer 60 are joined to the metal layer 18 of the substrate 10. For example, by heating and pressing at 250°C in a nitrogen atmosphere, the pillars 61 to 63 and the annular metal layer 60 are soldered to the metal layer 18 of the substrate 10. Similarly, the pillars 61 to 63 are joined to the wiring 27 of the substrate 20, and the annular metal layer 60 is joined to the metal layer 28. For example, by heating and pressing at 250°C in a nitrogen atmosphere, the pillars 61 to 63 are soldered to the wiring 27 of the substrate 20, and the annular metal layer 60 is soldered to the metal layer 28.

[0047] As shown in FIG. 6(b), a resist film 91 is formed to cover the regions of the lower surface 14 of the substrate 10 other than the regions where the coating metal layer 75 is formed. After the substrates 10 and 20 are diced into individual pieces, the diced chips are fixed to the protrusions 93 of the substrate 92 having protrusions by means of a tape 94 or the like. The width of the protrusions 93 is smaller than the chip size (for example, 200 μm or more smaller), and only the regions where the resist film 91 is formed are attached to the tape 94, and the regions where the resist film 91 is not formed are in a floating state from the tape 94. Next, a metal film is deposited on the chips fixed to the substrate 92 using a sputtering method. The metal film is formed on the entire surface of the chips except for the regions where the resist film 91 is formed. Thereby, the surface acoustic wave device 100 of Example 1 having the coating metal layer 75 on the surface is formed. Finally, the surface acoustic wave device 100 is peeled off from the tape 94 and the resist film 91 is removed to complete.

[0048] [Modification 1 of Example 1] FIG. 7 is a cross-sectional view of the elastic wave device according to Modification 1 of Example 1. FIG. 8(a) is a perspective view of the elastic wave device showing the coating region of the coating metal layer in Modification 1 of Example 1, and FIG. 8(b) is a plan view showing the lower surface of the substrate. In FIGS. 8(a) and 8(b), for clarity of the drawing, the region where the coating metal layer 75 is provided is hatched. Further, FIG. 8(b) is a plan view of the lower surface 14 seen through from above the substrate 10. As shown in FIGS. 7 and 8(a), in the elastic wave device 110 of Modification 1 of Example 1, the coating metal layer 75 covers the entire surface of all side surfaces 15 of the substrate 10, and the outer surface of the columnar portion 65a and the entire outer surface of a part 71 of the shield metal layer 70 among the outer surfaces of the annular metal layer 60. As shown in FIG. 8(b), the coating metal layer 75 extends from the side surface 15 to the lower surface 14 of the substrate 10 and is in electrical contact with the ground terminals 43 to 47 in the same manner as in Example 1. Since the other configurations are the same as those in Example 1, the description is omitted.

[0049] [Comparative Example] FIG. 9(a) is a cross-sectional view of the elastic wave device according to Comparative Example 1, FIG. 9(b) is a cross-sectional view of the elastic wave device according to Comparative Example 2, and FIG. 10 is a cross-sectional view of the elastic wave device according to Comparative Example 3. As shown in FIG. 9(a), in the elastic wave device 500 of Comparative Example 1, the shield metal layer 70 is not provided between the substrate 10 and the substrate 20, and the coating metal layer 75 electrically connected to the shield metal layer 70 is also not provided. The annular metal layer 60 is electrically connected to the ground terminal 44 through the via wiring 55 provided in the substrate 10. Since the other configurations are the same as those in Example 1, the description is omitted.

[0050] As shown in FIG. 9(b), in the elastic wave device 600 of Comparative Example 2, the coating metal layer 75 is not provided, and the annular metal layer 60 and the shield metal layer 70 are electrically connected to the ground terminal 44 through the via wiring 55 provided in the substrate 10. Since the other configurations are the same as those in Example 1, the description is omitted.

[0051] As shown in FIG. 10, in the elastic wave device 700 of Comparative Example 3, the shield metal layer 70 is not provided between the substrate 10 and the substrate 20. Since the other configurations are the same as those in Example 1, the description thereof will be omitted.

[0052] [Simulation 1] Simulations of the isolation of the elastic wave devices of Example 1, Comparative Example 1, and Comparative Example 2 were performed. The simulation conditions were as follows. Support substrates 11 and 12: Sapphire substrates with a thickness of 75 μm Piezoelectric layers 12 and 22: 42° rotated Y-cut X-propagating lithium tantalate layers with a thickness of 1 μm Via wirings 50 to 55: Copper films with a diameter of 40 μm Annular metal layer 60: A laminated film in which a 30-μm-thick Kovar layer is sandwiched between 20-μm-thick copper layers Shield metal layer 70: A 30-μm-thick Kovar layer Coating metal layer 75: A 1-μm-thick gold layer Transmission band of the transmission filter 19: 2500 MHz to 2570 MHz Receiving band of the receiving filter 29: 2620 MHz to 2690 MHz

[0053] FIG. 11 is a diagram showing the isolation characteristics of the elastic wave devices of Example 1, Comparative Example 1, and Comparative Example 2. The horizontal axis in FIG. 11 is the frequency [MHz], and the vertical axis is the attenuation amount [dB]. The attenuation amount indicates the leakage of the transmission signal to the receiving terminal 41. When the absolute value of the attenuation amount is large, the isolation is high, and when the absolute value of the attenuation amount is small, the isolation is low (the same applies to the following similar diagrams).

[0054] As shown in FIG. 11, in the transmission band of 2500 MHz to 2570 MHz and the reception band of 2620 MHz to 2690 MHz, the isolation characteristics of Example 1 and Comparative Example 2 are improved compared to Comparative Example 1. This is presumably because in Example 1 and Comparative Example 2, a shield metal layer 70 to which a ground potential is supplied is provided between the surface acoustic wave element 16 that constitutes the transmission filter 19 and the surface acoustic wave element 26 that constitutes the reception filter 29. That is, it is thought that the electromagnetic wave of the transmission filter 19 is shielded by the shield metal layer 70, suppressing the electromagnetic field coupling between the transmission filter 19 and the reception filter 29.

[0055] In the floor low-frequency region (around 2350 MHz to 2450 MHz) on the lower frequency side than the transmission band and the floor high-frequency region (around 2750 MHz to 2850 MHz) on the higher frequency side than the reception band, the isolation characteristics of Example 1 are improved compared to Comparative Example 2. This is considered to be due to the following reasons. In Comparative Example 2, the shield metal layer 70 is supplied with a ground potential by being connected to a ground terminal 44 via a via wiring 55 provided on the substrate 10. In this case, the inductance component of the via wiring 55 causes the ground performance of the shield metal layer 70 not to become sufficiently high. As a result, it is considered that it was difficult to improve the isolation characteristics in the floor low-frequency region and the floor high-frequency region in Comparative Example 2. On the other hand, in Example 1, the shield metal layer 70 is supplied with a ground potential by being connected to ground terminals 43 to 47 via a covering metal layer 75 that covers the side surface 15 of the substrate 10. Thereby, the inductance component is reduced and the ground performance of the shield metal layer 70 is improved. As a result, it is considered that the isolation characteristics in the floor low-frequency region and the floor high-frequency region were improved in Example 1. Further, since the ground performance of the shield metal layer 70 is improved in Example 1, it is considered that the isolation characteristics in the transmission band are also improved compared to Comparative Example 2.

[0056] In the simulation, in Example 1, compared with Comparative Example 2, the isolation at 2400 MHz (floor low-frequency region) was improved by about 5.3 dB, and the isolation at 2800 MHz (floor high-frequency region) was improved by about 7.4 dB. Also, in Example 1, compared with Comparative Example 2, the isolation characteristics in the transmission band were improved by about 3.7 dB.

[0057] In Comparative Example 2, it is conceivable to improve the grounding performance of the shield metal layer 70 by increasing the number of via wirings provided on the support substrate 11 to electrically connect the annular metal layer 60 and the shield metal layer 70 to the terminal for ground. However, due to the influence of the inductance component of the via wiring and the like, the grounding performance of the shield metal layer 70 cannot be sufficiently improved, and the improvement effect of the isolation characteristics is not sufficiently high. Also, since a plurality of via wirings are formed, the formation position of the via wiring is restricted depending on the formation position of the terminal and the like, so the improvement effect of the isolation characteristics varies depending on the device and it is difficult to obtain a stable improvement effect. Further, when forming a plurality of via wirings, the strength of the substrate is reduced. Also, when the annular metal layer 60 and the shield metal layer 70 are electrically connected to the terminal for ground using via wirings and / or through holes, etc., increasing the number of via wirings and / or through holes compresses the designable area on the substrate, but it is possible to secure a designable area by connecting not only the via wiring but also the coating metal layer 75 to the terminal for ground.

[0058] [Simulation 2] Simulations of the isolation of the surface acoustic wave devices of Example 1, Modification 1 of Example 1, and Comparative Example 2 were performed. The simulation conditions were the same as those of Simulation 1 described above.

[0059] FIG. 12 is a diagram showing the isolation characteristics of the elastic wave devices of Example 1, Modified Example 1 of Example 1, and Comparative Example 2. The horizontal axis in FIG. 12 is the frequency [MHz], and the vertical axis is the attenuation amount [dB]. As shown in FIG. 12, in Modified Example 1 of Example 1, the isolation characteristics are improved to approximately the same extent as in Example 1. In Modified Example 1 of Example 1, since the coating metal layer 75 is provided so as to cover only the side surface 15 of the substrate 10 and the columnar portions 65a located on the substrate 10 side of the annular metal layer 60 and a part 71 of the shield metal layer 70, the simulation results in FIG. 12 show that even by covering only a part of the elastic wave device with the coating metal layer 75, the isolation characteristics can be sufficiently improved.

[0060] [Simulation 3] Simulations of the isolation of the elastic wave devices of Example 1, Comparative Example 1, and Comparative Example 3 were conducted. The simulation conditions were the same as those of Simulation 1 described above.

[0061] FIG. 13 is a diagram showing the isolation characteristics of the elastic wave devices of Example 1, Comparative Example 1, and Comparative Example 3. The horizontal axis in FIG. 13 is the frequency [MHz], and the vertical axis is the attenuation amount [dB]. As shown in FIG. 13, Comparative Example 1 and Comparative Example 3 had similar isolation characteristics. In Comparative Example 3, although the coating metal layer 75 was provided, the shield metal layer 70 was not provided. Therefore, the simulation results in FIG. 13 show that the effect of improving the isolation characteristics is small by only providing the coating metal layer 75 without providing the shield metal layer 70. That is, it shows that the isolation characteristics can be improved by providing both the shield metal layer 70 and the coating metal layer 75 and improving the ground performance of the shield metal layer 70.

[0062] [Modified Examples 2 and 3 of Example 1] FIG. 14(a) and FIG. 14(b) are perspective views of an elastic wave device showing the coating regions of the coating metal layers in Modifications 2 and 3 of Example 1. In FIGS. 14(a) and 14(b), for the sake of clarity of the drawing, hatching is applied to the region where the coating metal layer 75 is provided, and the outer shape of the coating metal layer 75 is indicated by a thick line. As shown in FIG. 14(a), in the elastic wave device 120 of Modification 2 of Example 1, the coating metal layer 75 is provided on two opposing side surfaces 15 out of a plurality of side surfaces 15 of the substrate 10. The side surfaces 15 provided with the coating metal layer 75 are not limited to the case of opposing side surfaces 15, and may be adjacent side surfaces 15. Also, although not shown, the coating metal layer 75 may be provided on three side surfaces 15 out of a plurality of side surfaces 15 of the substrate 10. As shown in FIG. 14(b), in the elastic wave device 130 of Modification 3 of Example 1, the coating metal layer 75 may be provided on the side surface 15 of the substrate 10 so as to linearly extend from a portion of each side of the lower surface 14 of the substrate 10 close to the ground terminals 43 to 47 to the side surface 15 of the substrate 10. As described above, as long as the coating metal layer 75 covers more than half of the regions of the plurality of side surfaces 15 of the substrate 10, the coating metal layer 75 may cover the plurality of side surfaces 15 in any manner.

[0063] According to Example 1 and its modifications, a shield metal layer 70 (first metal layer) is provided between the elastic wave element 16 provided on the substrate 10 and the elastic wave element 26 provided on the substrate 20. The shield metal layer 70 is electrically connected to the ground terminal 44 by a coating metal layer 75 (second metal layer) provided to cover more than half of the regions of the plurality of side surfaces 15 of the substrate 10. Thereby, the electromagnetic shielding effect is enhanced by improving the ground performance of the shield metal layer 70, and the isolation characteristics can be improved. Also, since the coating metal layer 75 is provided to cover the side surface 15 of the substrate 10, the electromagnetic field coupling between the elastic wave element 16 provided on the substrate 10 and a device outside the elastic wave device 100 is suppressed. The region covered by the coating metal layer 75 may be, for example, defined by the range of the substrate 10 from an X-ray image, an optical microscope, or an SEM image of the cross section of the elastic wave device, and the optical microscope or SEM image of each side surface may be measured to obtain the ratio of the region.

[0064] The coated metal layer 75 preferably covers a plurality of side surfaces 15 of the substrate 10 from the upper surface 13 side end to the lower surface 14 side end of the plurality of side surfaces 15. Also, from the viewpoint of improving the ground performance of the shield metal layer 70, the coated metal layer 75 is preferably provided on two or more of the plurality of side surfaces 15 of the substrate 10 and covers at least a part of each of the two or more side surfaces 15, more preferably provided on three or more side surfaces 15 and covers at least a part of each of the three or more side surfaces 15. More preferably, the coated metal layer 75 is provided on each of the plurality of side surfaces 15 of the substrate 10 and covers at least a part of each of the plurality of side surfaces 15.

[0065] From the viewpoint of improving the ground performance of the shield metal layer 70, the coated metal layer 75 preferably covers 60% or more of the area of the plurality of side surfaces 15 of the substrate 10, more preferably 75% or more, still more preferably 90% or more, and even more preferably covers the entire surface. That is, it is even more preferable that the coated metal layer 75 is provided on each of the plurality of side surfaces 15 of the substrate 10 and covers the entire surface of each of the plurality of side surfaces 15.

[0066] The coated metal layer 75 preferably contacts at least a part of the surface of the annular metal layer 60 from the side surface 15 of the substrate 10. Thereby, it is possible to realize, with a simple configuration, electrically connecting the shield metal layer 70 to the ground terminal 44 via the coated metal layer 75. Incidentally, the columnar portions 65a and 65b may be formed of an insulating material instead of a metal material. In this case, the coated metal layer 75 preferably extends from the side surface 15 of the substrate 10 to the surface of a part 71 of the shield metal layer 70.

[0067] When the elastic wave elements 16 and 26 are sealed by the annular metal layer 60 in the gap 82 between the substrate 10 and the substrate 20, the coating metal layer 75 preferably covers from the side surface 15 of the substrate 10 via the surface of the annular metal layer 60 to the side surface 25 and the upper surface 23 of the substrate 20. By providing the coating metal layer 75 on the side surface 15 and the upper surface 23 of the substrate 20, the electromagnetic field coupling between the elastic wave element 26 provided on the substrate 20 and an external device can be suppressed. Therefore, deterioration of characteristics can be suppressed. The coating metal layer 75 preferably covers more than half of the regions of the plurality of side surfaces 25 and the upper surface 23 of the substrate 20, more preferably covers more than 3 / 4 of the regions, and still more preferably covers the entire surfaces of the plurality of side surfaces 25 and the entire surface of the upper surface 23 of the substrate 20.

[0068] The shield metal layer 70 may be electrically connected to the ground terminal 44 by both the coating metal layer 75 and the via wiring 55 (see FIGS. 9(a) and 9(b)) penetrating the substrate 10. Thereby, a designable area on the substrate 10 can be secured well.

Example

[0069] FIG. 15 is a cross-sectional view of the elastic wave device according to Example 2. As shown in FIG. 15, in the elastic wave device 200 of Example 2, the elastic wave element 16 provided on the substrate 10 and the elastic wave element 26 provided on the substrate 20 do not face each other. That is, the piezoelectric layer 22 is provided on the surface of the support substrate 21 opposite to the substrate 10, and the elastic wave element 26 is provided on the upper surface 23 of the substrate 20. The elastic wave element 26 provided on the substrate 20 is electrically connected to the receiving terminal 41 via the via wiring 81, the pillar 61, and the via wiring 51 penetrating the substrate 20.

[0070] An annular metal layer 60a is provided between the substrate 10 and the substrate 20, surrounding the elastic wave element 16. The elastic wave element 16 is sealed within a gap 83 formed between the substrate 10 and the substrate 20 by the annular metal layer 60a. An annular metal layer 60b is provided on the upper surface 23 of the substrate 20, surrounding the elastic wave element 26. A lid 66 is provided on the annular metal layer 60b. The elastic wave element 26 is sealed within a gap 84 formed between the substrate 20 and the lid 66 by a sealing portion composed of the annular metal layer 60b and the lid 66.

[0071] The shield metal layer 70 is provided on the lower surface 24 of the substrate 20, positioned within the gap 83. The coating metal layer 75 is provided so as to cover the entire surface of all the side surfaces 15 of the substrate 10, the entire outer surface of the annular metal layer 60a, the entire outer surface of the shield metal layer 70, the entire surface of all the side surfaces 25 of the substrate 20, the entire outer surface of the annular metal layer 60b, and the entire outer surface of the lid 66. Since other configurations are the same as those of the first embodiment, the description thereof is omitted.

[0072] Also in the elastic wave device 200 of the second embodiment, the shield metal layer 70 is electrically connected to the ground terminal 44 by the coating metal layer 75 provided so as to cover more than half of the area of a plurality of side surfaces 15 of the substrate 10. Therefore, by improving the ground performance of the shield metal layer 70, the electromagnetic shielding effect is enhanced, and the isolation characteristics can be improved.

[0073] When the elastic wave element 16 is provided on the upper surface 13 of the substrate 10 and the elastic wave element 26 is provided on the upper surface 23 of the substrate 20, it is preferable that the coating metal layer 75 covers from the side surface 15 of the substrate 10 via the surface of the annular metal layer 60a to the side surface 25 of the substrate 20 and the surface of the sealing portion (annular metal layer 60b and lid 66). By providing the coating metal layer 75 on the side surface 15 of the substrate 20 and the surface of the sealing portion (annular metal layer 60b and lid 66), electromagnetic field coupling between the elastic wave element 26 provided on the substrate 20 and an external device can be suppressed. Therefore, deterioration of characteristics can be suppressed. The coating metal layer 75 preferably covers more than half of the regions of the plurality of side surfaces 25 of the substrate 20 and the surface of the sealing portion, more preferably covers 3 / 4 or more of the regions, and still more preferably covers the entire surfaces of the plurality of side surfaces 25 of the substrate 20 and the entire surface of the sealing portion.

[0074] In Examples 1 and 2, the case where the elastic wave elements 16 and 26 excite surface elastic waves is shown as an example, but the case of exciting Love waves or elastic boundary waves may also be possible.

Example

[0075] FIG. 16(a) is a cross-sectional view of the elastic wave device according to Example 3, and FIG. 16(b) is a cross-sectional view of the elastic wave element in Example 3. In FIG. 16(b), the elastic wave element 16a is taken as an example, but the elastic wave element 26a is the same. As shown in FIG. 16(a), in the elastic wave device 300 of Example 3, the elastic wave element 16a is provided on the upper surface 13 of the substrate 10a, and the elastic wave element 26a is provided on the lower surface 24 of the substrate 20a. The substrates 10a and 20a are insulating substrates such as silicon oxide substrates, for example. As shown in FIG. 16(b), the elastic wave element 16a is a piezoelectric thin film resonator in which the lower electrode 35, the piezoelectric film 36, and the upper electrode 37 are provided on the substrate 10a, and the piezoelectric film 36 is sandwiched between the lower electrode 35 and the upper electrode 37. A gap 38 is formed between the lower electrode 35 and the substrate 10a. The region where the piezoelectric film 36 is sandwiched between the lower electrode 35 and the upper electrode 37 is the resonance region, and in the resonance region, the lower electrode 35 and the upper electrode 37 excite elastic waves in the thickness longitudinal vibration mode in the piezoelectric film 36. The lower electrode 35 and the upper electrode 37 are metal films such as ruthenium films, for example. The piezoelectric film 36 is an aluminum nitride film, for example. Since the other configurations are the same as those in Example 1, the description thereof is omitted.

[0076] In Examples 1 and 2, the case where the elastic wave elements 16 and 26 are surface acoustic wave resonators was taken as an example. However, as in Example 3, the elastic wave elements 16a and 26a may be piezoelectric thin film resonators. Also, one of the elastic wave elements provided on the two substrates may be a surface acoustic wave resonator and the other may be a piezoelectric thin film resonator.

[0077] In Examples 1 to 3, the case where the transmission filter 19 is configured by a plurality of elastic wave elements 16 or 16a provided on the substrate 10 or 10a, and the reception filter 29 is configured by a plurality of elastic wave elements 26 or 26a provided on the substrate 20 or 20a is shown as an example. However, the present invention is not limited to this case. For example, a reception filter may be configured by a plurality of elastic wave elements 16 or 16a, and a transmission filter may be configured by a plurality of elastic wave elements 26 or 26a. Further, one of two transmission filters having different passbands for other band simultaneous operation may be configured by a plurality of elastic wave elements 16 or 16a, and the other may be configured by a plurality of elastic wave elements 26 or 26a. Also, one of two reception filters having different passbands for other band simultaneous operation may be configured by a plurality of elastic wave elements 16 or 16a, and the other may be configured by a plurality of elastic wave elements 26 or 26a. Further, a multiplexer may be configured including the transmission filter 19 and the reception filter 29.

Example

[0078] FIG. 17 is a perspective view of a communication module according to Example 4. As shown in FIG. 17, the communication module 400 of Example 4 has one or more ICs (Integrated Circuits) 86, one or more chip inductors 87, one or more chip capacitors 88, and one or more elastic wave devices 100 of Example 1 mounted on a circuit board 85. Since the elastic wave device 100 is provided with a coating metal layer 75 on its surface, electromagnetic field coupling with other devices mounted on the circuit board 85 is suppressed. That is, it is possible to suppress the influence of the electromagnetic field given from the elastic wave device 100 to the outside, and it is also possible to suppress the influence of the electromagnetic field received by the elastic wave device 100 from the outside. In Example 4, the case where the elastic wave device 100 of Example 1 is mounted is shown as an example. However, the elastic wave devices of Modifications 1 to 3 of Example 1, Example 2, and Example 3 may be mounted.

[0079] 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 changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of Signs

[0080] 10, 10a, 20, 20a Substrate 11, 21 Support substrate 12, 22 Piezoelectric layer 13, 23 Upper surface 14, 24 Lower surface 15, 25 Side surface 16, 16a, 26, 26a SAW device 17, 27 Wiring 18, 28 Metal layer 19 Transmission filter 29 Reception filter 40 - 47 Terminals 50 - 55 Via wiring 60, 60a, 60b Annular metal layer 61 - 63 Pillars 65a, 65b Columnar parts 66 Lid 70 Shield metal layer 71 Part of the shield metal layer 72 Resin film 75 Coated metal layer 81 Via wiring 82 - 84 Voids 85 Circuit board 86 IC 87 Chip inductor 88 Chip capacitor 100, 110, 120, 130, 200, 300, 500, 600, 700 SAW device 400 Communication module

Claims

1. A first substrate having a first surface, a second surface opposite to the first surface, and a plurality of side surfaces connecting the first surface and the second surface; A first elastic wave element provided on the first surface of the first substrate; A second substrate provided on the first elastic wave element on the first surface of the first substrate and having a gap with the first substrate; A second elastic wave element provided on the second substrate; A ground terminal provided on the second surface of the first substrate; An annular metal layer provided on the first surface of the first substrate surrounding the first elastic wave element and having a rectangular shape in plan view for sealing the first elastic wave element in the gap between the first substrate and the second substrate; A first metal layer provided between the first elastic wave element and the second elastic wave element, located in the gap, and connected to the annular metal layer at all sides of the annular metal layer; An elastic wave device comprising: a second metal layer provided across the side surfaces at all sides of the annular metal layer from all of the plurality of side surfaces of the first substrate, covering more than half of the region of the plurality of side surfaces, and electrically connecting the first metal layer and the ground terminal.

2. The elastic wave device according to claim 1, wherein the second metal layer is provided across from the end on the first surface side to the end on the second surface side on each of the plurality of side surfaces of the first substrate.

3. The elastic wave device according to claim 1 or 2, wherein the second metal layer is provided across from all of the plurality of side surfaces of the first substrate to the second surface and is connected to a plurality of the ground terminals.

4. The elastic wave device according to any one of claims 1 to 3, wherein the second metal layer covers more than 90% of the region of the plurality of side surfaces of the first substrate.

5. The annular metal layer includes a part of the first metal layer, The elastic wave device according to any one of claims 1 to 4, wherein the second metal layer is provided from all of the plurality of side surfaces of the first substrate to the part.

6. The second substrate has a third surface facing the first substrate, a fourth surface opposite to the third surface, and a plurality of side surfaces connecting the third surface and the fourth surface, The second elastic wave element is provided on the third surface and is sealed in the gap together with the first elastic wave element by the annular metal layer, The elastic wave device according to any one of claims 1 to 5, wherein the second metal layer covers all of the plurality of side surfaces of the first substrate, passes through side surfaces of the annular metal layer, and covers all of the plurality of side surfaces of the second substrate and the fourth surface.

7. The elastic wave device according to any one of claims 1 to 5, further comprising a sealing portion provided on a fourth surface of the second substrate opposite to a third surface of the second substrate facing the first surface of the first substrate. The second elastic wave element is provided on the fourth surface and is sealed in a gap different from the gap between the second substrate and the sealing portion by the sealing portion. The elastic wave device according to any one of claims 1 to 5, wherein the second metal layer covers all of the plurality of side surfaces of the first substrate, passes through side surfaces of the annular metal layer, and covers all of the plurality of side surfaces connecting the third surface and the fourth surface and the surface of the sealing portion.

8. A third metal layer provided on the first substrate and joined with the annular metal layer, The elastic wave device according to any one of claims 1 to 7, further comprising via wirings that penetrate the first substrate from the first surface to the second surface and electrically connect the third metal layer and the ground terminal.

9. A first elastic wave filter is configured by a plurality of the first elastic wave elements provided on the first substrate. A second elastic wave filter having a passband different from that of the first elastic wave filter is configured by a plurality of the second elastic wave elements provided on the second substrate. The elastic wave device according to any one of claims 1 to 8, wherein a multiplexer is configured to include the first elastic wave filter and the second elastic wave filter.

10. A circuit board, A communication module comprising the elastic wave device according to any one of claims 1 to 9 mounted on the circuit board.

Images