Elastic wave devices

Abstract

To provide an elastic wave device that allows for easy adjustment of inductance. [Solution] The elastic wave device comprises a first substrate 10 having a first elastic wave element on its upper surface and ground terminals Gnd1 to 4 on its lower surface; a second substrate 20 having a second elastic wave element and provided on the first substrate 10; an annular metal layer 60 provided between the first substrate 10 and the second substrate 20 surrounding the first elastic wave element; a metal portion 25b provided on the second substrate 20 and connected to the second elastic wave element; an intermediate metal layer 40 provided between the first elastic wave element and the second elastic wave element, having a connection portion 45 to which at least the metal portion 25b is connected, and a slit 46 located away from the connection portion 45 between the connection portion 45 and the side surface 13c of the first substrate 10 that is closest to the connection portion 45; and an outer metal layer 35 provided from all four side surfaces 13a to 13d of the first substrate 10 to the annular metal layer 60, electrically connecting the intermediate metal layer 40 and the ground terminals Gnd1 to 4.

Description

[Technical Field]

[0001] The present invention relates to an acoustic wave device. [Background Art]

[0002] For size reduction of acoustic wave devices, it is known to provide a second substrate having a second acoustic wave element on a first substrate having a first acoustic wave element. In this case, it is known to provide a metal layer between the first acoustic wave element and the second acoustic wave element to suppress electromagnetic interference between the first acoustic wave element and the second acoustic wave element (see, for example, Patent Documents 1 to 3). It is also known that an attenuation pole in frequency characteristics shifts depending on the inductance of an inductor connected between an acoustic wave filter and a ground (see, for example, Patent Document 4). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese National Publication of International Patent Application No. 2008-546207 [Patent Document 2] Japanese Unexamined Patent Publication No. 2017-118273 [Patent Document 3] Japanese Unexamined Patent Publication No. 2022-72241 [Patent Document 4] Japanese Unexamined Patent Publication No. 2013-118584 [Summary of Invention] [Problem to be Solved by Invention]

[0004] In order to adjust the position of an attenuation pole in frequency characteristics, a configuration that enables easy adjustment of the inductance between an acoustic wave filter and a ground is desired.

[0005] The present invention has been made in view of the above problem, and an object of the present invention is to enable easy adjustment of inductance. [Means for Solving Problem]

[0006] The present invention relates to an elastic wave device comprising: a first substrate having a rectangular shape in plan view, having a first surface, a second surface, and four sides connecting the first surface and the second surface; a first elastic wave element provided on the first surface; a ground terminal provided on the second surface; a second substrate provided on the first substrate with a gap between it and the first substrate that exposes the first elastic wave element; a second elastic wave element provided on the second substrate; an annular metal layer provided between the first substrate and the second substrate surrounding the first elastic wave element; a metal portion provided on the second substrate and electrically connected to the second elastic wave element; an intermediate metal layer provided between the first elastic wave element and the second elastic wave element, having a slit provided away from the connection portion between at least the connection portion where the metal portion is connected and the first side of the four sides closest to the connection portion; and an outer metal layer provided from all four sides of the first substrate to the annular metal layer, electrically connecting the intermediate metal layer and the ground terminal.

[0007] In the above configuration, the slit can be provided so as to block the space between two of the four sides and the connecting portion.

[0008] In the above configuration, the slit can be provided so as to block the space between three of the four sides and the connecting portion.

[0009] In the above configuration, the slit has a first portion located between the first side surface and the connecting portion and having a longitudinal direction along the first side surface, and a second portion having a longitudinal direction along the second side surface intersecting the first side surface, wherein the second portion is provided extending from the first portion to beyond the center of the second side surface.

[0010] In the above configuration, the annular metal layer is rectangular in shape when viewed from above, and the intermediate metal layer can be connected to all sides of the annular metal layer.

[0011] In the above configuration, the second elastic wave element is provided on the surface of the second substrate opposite to the first substrate, and the metal portion can be provided penetrating the second substrate.

[0012] In the above configuration, the second elastic wave element can be provided on the surface of the second substrate that faces the first substrate, and the metal portion can be provided on the surface that faces the first substrate.

[0013] The present invention relates to a first substrate having a rectangular shape in plan view, having a first surface, a second surface, and four sides connecting the first surface and the second surface; a first elastic wave element provided on the first surface; a ground terminal provided on the second surface; a first metal part that penetrates the first substrate from the first surface to the second surface and is electrically connected to the ground terminal; a second metal part provided on the first surface and electrically connected to the first metal part; and a first base having a gap between it and the first substrate in which the first elastic wave element is exposed. The elastic wave device comprises a second substrate provided on a plate, a second elastic wave element provided on the second substrate, an annular metal layer provided between the first substrate and the second substrate surrounding the first elastic wave element, a third metal part provided on the second substrate and electrically connected to the second elastic wave element, and an intermediate metal layer provided between the first elastic wave element and the second elastic wave element, having a slit that, in a plan view, collectively surrounds a first connection portion where the second metal part connects and a second connection portion where the third metal part connects.

[0014] In the above configuration, the region enclosed by the slits is spiral-shaped in a plan view, the first connecting portion is located at one end of the spiral-shaped region, and the second connecting portion is located at the other end.

[0015] In the above configuration, a first elastic wave filter can be formed by the first elastic wave element, and a second elastic wave filter can be formed by the second elastic wave element. [Effects of the Invention]

[0016] According to the present invention, inductance can be easily adjusted. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] [Figure 1] 1(a) and 1(b) are cross-sectional views of an acoustic wave device according to Example 1. [Figure 2] 2(a) is a plan view of a second substrate in Example 1, 2(b) is a plan view of an intermediate metal layer, and 2(c) is a plan view of a first substrate. [Figure 3] 3(a) is a plan view of a series resonator and a parallel resonator in Example 1, 3(b) is a cross-sectional view of another example of the series resonator and the parallel resonator, and 3(c) is a plan view of a DMS filter in Example 1. [Figure 4] 4(a) and 4(b) are cross-sectional views of an acoustic wave device according to a comparative example. [Figure 5] 5(a) is a plan view of a second substrate in the comparative example, 5(b) is a plan view of an intermediate metal layer, and 5(c) is a plan view of a first substrate. [Figure 6] 6(a) is a diagram showing simulation results of attenuation versus frequency in Example 1 and the comparative example, and 6(b) is an enlarged view of the vicinity of the passband in 6(a). [Figure 7] 7(a) and 7(b) are plan views of intermediate metal layers in Modification 1 and Modification 2 of Example 1, respectively. [Figure 8] 8(a) and 8(b) are cross-sectional views of an acoustic wave device according to Example 2. [Figure 9] 9(a) is a plan view of a second substrate in Example 2, 9(b) is a plan view of an intermediate metal layer, and 9(c) is a plan view of a first substrate. [Figure 10] 10 is a cross-sectional view of an acoustic wave device according to Example 3. MODES FOR CARRYING OUT THE INVENTION

[0018] The embodiments of the present invention will be described below with reference to the drawings. [Examples]

[0019] Figures 1(a) and 1(b) are cross-sectional views of the elastic wave device 100 according to Embodiment 1. Figure 1(a) is a schematic cross-sectional view showing the part related to the connection to the ground terminal, and Figure 1(b) is a schematic cross-sectional view showing the part related to the connection to the signal terminal. Figure 2(a) is a plan view of the second substrate 20 in Embodiment 1, Figure 2(b) is a plan view of the intermediate metal layer 40, and Figure 2(c) is a plan view of the first substrate 10. In Figure 2(c), the antenna terminal Ant, the transmit terminal Tx, the receive terminal Rx, and the ground terminals Gnd1 to Gnd4 provided on the lower surface 12 of the first substrate 10 are shown by dashed lines. The stacking direction of the first substrate 10 and the second substrate 20 is the Z direction, and the directions that are mutually orthogonal in the planar direction of the first substrate 10 are the X direction and the Y direction.

[0020] As shown in Figures 1(a) and 1(b), the first piezoelectric layer 14 is bonded to the upper surface 11 of the first substrate 10. An insulating layer such as silicon oxide, aluminum oxide, and / or aluminum nitride may be provided between the first substrate 10 and the first piezoelectric layer 14. In this way, the first piezoelectric layer 14 is bonded to the first substrate 10 directly or indirectly.

[0021] A first elastic wave element 50a is provided on the first piezoelectric layer 14. Metal parts 15a and 15b are provided on the first substrate 10, penetrating from the upper surface 11 to the lower surface 12. The metal parts 15a and 15b are also called via wiring. Wiring 16 is provided from the first elastic wave element 50a to the upper surface of the metal parts 15a and 15b. The first elastic wave element 50a and the metal parts 15a and 15b are electrically connected by the wiring 16. Electrical connection basically means DC conduction, but conduction of signals (AC) in the frequency band of approximately 500MHz to 2500MHz is also permitted (the same applies below).

[0022] A bottom metal layer 30 is provided on the bottom surface 12 of the first substrate 10. An insulating film 31 is provided covering the bottom metal layer 30. An antenna terminal Ant, a transmitting terminal Tx, a receiving terminal Rx, and ground terminals Gnd1 to Gnd4 are provided on the insulating film 31 (in Figures 1(a) and 1(b), only the antenna terminal Ant, the transmitting terminal Tx, and the ground terminals Gnd1 and Gnd2 are shown). The bottom metal layer 30 and the ground terminals Gnd1 to Gnd4 are connected by a metal part 32b that penetrates the insulating film 31. The metal part 32b is also called a via wiring. A metal part 15b is connected to the bottom metal layer 30. As a result, the first elastic wave element 50a is electrically connected to the ground terminals Gnd1 to Gnd4 via the wiring 16, the metal part 15b, the bottom metal layer 30, and the metal part 32b.

[0023] A metal portion 32a that penetrates the insulating film 31 is provided and connected to the antenna terminal Ant, the transmitting terminal Tx, and the receiving terminal Rx. The metal portion 32a is also called a via wiring. An annular through hole 33 is provided in the lower metal layer 30 around the metal portion 32a. The insulating film 31 is embedded in the through hole 33. Therefore, the antenna terminal Ant, the transmitting terminal Tx, and the receiving terminal Rx are not connected to the ground terminals Gnd1 to Gnd4 via the lower metal layer 30. The metal portion 15a is connected to the metal portion 32a. As a result, the first elastic wave element 50a is connected between the antenna terminal Ant and the transmitting terminal Tx via the wiring 16, the metal portion 15a, and the metal portion 32a.

[0024] As shown in Figures 1(a), 1(b), and 2(c), the first piezoelectric layer 14 is not provided in the peripheral region of the first substrate 10. In a plan view from the +Z direction, an annular metal layer 60 is provided on the first substrate 10 so as to surround the first piezoelectric layer 14 and the first elastic wave element 50a. The first substrate 10 is rectangular in plan view. The rectangular shape includes cases where the corners are rounded and cases where each side is ridged (the same applies hereafter). The annular metal layer 60 is provided along the outer circumference of the first substrate 10 and is rectangular in plan view. The annular metal layer 60 has four sides 61a to 61d.

[0025] A series resonator S11 and S12 and a parallel resonator P11 are formed by a first elastic wave element 50a provided on the first piezoelectric layer 14. A ladder-type filter 81 is formed by the series resonators S11 and S12 and the parallel resonator P11. The series resonators S11 and S12 are connected in series between the transmitting terminal Tx and the antenna terminal Ant via metal parts 15a and 32a. One end of the parallel resonator P11 is connected to the wiring 16 between the series resonators S11 and S12. The other end of the parallel resonator P11 is connected to the ground terminals Gnd1 to Gnd4 via metal part 15b, the lower metal layer 30, and metal part 32b.

[0026] As shown in Figures 1(a) and 1(b), a second substrate 20 is provided on an annular metal layer 60. A gap 18 is formed between the first substrate 10 and the second substrate 20. The first elastic wave element 50a is sealed in the gap 18 by the annular metal layer 60 and the second substrate 20. A second piezoelectric layer 24 is bonded to the upper surface 21 of the second substrate 20. An insulating layer such as silicon oxide, aluminum oxide, and / or aluminum nitride may be provided between the second substrate 20 and the second piezoelectric layer 24. In this way, the second piezoelectric layer 24 is bonded to the second substrate 20 directly or indirectly.

[0027] A second elastic wave element 50b is provided on the second piezoelectric layer 24. Metal parts 25a and 25b are provided on the second substrate 20, penetrating from the upper surface 21 to the lower surface 22. The metal parts 25a and 25b are also called via wiring. Wiring 26 is provided from the second elastic wave element 50b to the upper surface of the metal parts 25a and 25b. The second elastic wave element 50b and the metal parts 25a and 25b are electrically connected by the wiring 26.

[0028] The metal part 25a is connected to a metal part 19 provided in the gap 18 between the first substrate 10 and the second substrate 20. The metal part 19 is also called a pillar metal. The metal part 19 is connected to a metal part 15a, and via the metal part 15a, it is connected to the antenna terminal Ant and the receiving terminal Rx. Thus, the second elastic wave element 50b is connected between the antenna terminal Ant and the receiving terminal Rx via the wiring 26, metal part 25a, metal part 19, metal part 15a, and metal part 32a.

[0029] As shown in Figures 1(a), 1(b), and 2(b), an intermediate metal layer 40 is provided on the lower surface 22 of the second substrate 20. The intermediate metal layer 40 is rectangular in plan view and is connected to all four sides 61a to 61d of the annular metal layer 60. The intermediate metal layer 40 has four sides 41a to 41d. The metal portion 25b provided on the second substrate 20 is connected to the intermediate metal layer 40. The portion to which the metal portion 25b is connected is called the connection portion 45. The portion to which the metal portion 25a is connected is called the connection portion 44. The intermediate metal layer 40 has an annular through hole 43 surrounding the connection portion 44.

[0030] A slit 46 is provided between the edge 41c closest to one of the four edges 41a to 41d of the intermediate metal layer 40 and the connection portion 45, and away from the connection portion 45. In other words, the slit 46 is located between the connection portion 45 and the side surface 13c of the first substrate 10. The slit 46 penetrates the intermediate metal layer 40. In Embodiment 1, the slit 46 is U-shaped and surrounds the connection portion 45 from three directions. That is, the slit 46 has a first portion 47 located between the edge 41c and the connection portion 45 and having a longitudinal direction along the edge 41c, and a second portion 48 having a longitudinal direction along the edges 41b and 41d that intersect the edge 41c. The length L1 of the first portion 47 in the direction along the edge 41c is at least twice the maximum length L2 of the connection portion 45. The second part 48 extends from the first part 47 beyond the midpoints 42a and 42b of sides 41b and 41d.

[0031] As shown in Figures 1(a), 1(b), and 2(a), the second piezoelectric layer 24 is not provided in the peripheral region of the second substrate 20. In a plan view, an annular metal layer 70 is provided on the second substrate 20 so as to surround the second piezoelectric layer 24 and the second elastic wave element 50b. The annular metal layer 70 is rectangular in a plan view. A lid 34 is provided on the annular metal layer 70. A gap 28 is formed between the second substrate 20 and the lid 34. The second elastic wave element 50b is sealed in the gap 28 by the annular metal layer 70 and the lid 34. The second elastic wave element 50b provided on the second piezoelectric layer 24 forms a double-mode surface acoustic wave (DMS) filter 80, a series resonator S21, and a parallel resonator P21. An insulating film 27 is provided where the wiring 26 intersects.

[0032] As shown in Figures 1(a), 1(b), and 2(a) to 2(c), an outer metal layer 35 is provided covering all four sides 13a to 13d of the first substrate 10, all outer surfaces of the annular metal layer 60, all outer surfaces of the intermediate metal layer 40, all sides of the second substrate 20, all outer surfaces of the annular metal layer 70, and the surface of the lid 34. The outer metal layer 35 is connected to the bottom metal layer 30 at the four sides 13a to 13d of the first substrate 10. Therefore, the intermediate metal layer 40 is electrically connected to the ground terminals Gnd1 to Gnd4 via the annular metal layer 60, the outer metal layer 35, the bottom metal layer 30, and the metal part 32b.

[0033] The series resonator S21 and DMS filter 80, provided on the second piezoelectric layer 24, are connected in series between the antenna terminal Ant and the receiving terminal Rx via metal parts 25a, 19, 15a, and 32a. The DMS filter 80 is also connected to the ground terminals Gnd1 to Gnd4 via metal part 25b, intermediate metal layer 40, annular metal layer 60, outer metal layer 35, bottom metal layer 30, and metal part 32b. One end of the parallel resonator P21 is connected to the wiring 26 between the series resonator S21 and the DMS filter 80. The other end of the parallel resonator P21 is connected to the ground terminals Gnd1 to Gnd4 via metal part 25b, intermediate metal layer 40, annular metal layer 60, outer metal layer 35, bottom metal layer 30, and metal part 32b.

[0034] A duplexer is formed, for example, by a ladder-type filter 81 provided on the first substrate 10 and a DMS filter 80 provided on the second substrate 20, to which a series resonator S21 and a parallel resonator P21 are connected. The ladder-type filter 81 allows the high-frequency signals in the transmission band from the transmission terminal Tx to pass to the antenna terminal Ant as the transmission signal, and suppresses signals of other frequencies. The DMS filter 80 allows the high-frequency signals in the reception band from the antenna terminal Ant to pass to the reception terminal Rx as the received signal, and suppresses signals of other frequencies.

[0035] The first substrate 10 and the second substrate 20 are, for example, a sapphire substrate, an alumina substrate, a spinel substrate, a quartz substrate, a crystal substrate, a silicon carbide substrate, or a silicon substrate. The first piezoelectric layer 14 and the second piezoelectric layer 24 are, for example, a single-crystal lithium tantalate layer, a single-crystal lithium niobate layer, or a single-crystal crystal layer. The metal parts 15a and 15b, the wiring 16, the metal parts 25a and 25b, the wiring 26, the bottom metal layer 30, the metal parts 32a and 32b, the annular metal layer 60, the annular metal layer 70, the antenna terminal Ant, the transmitting terminal Tx, the receiving terminal Rx, and the ground terminals Gnd1 to Gnd4 are metal layers containing, for example, titanium, copper, aluminum, platinum, nickel, and / or gold.

[0036] The intermediate metal layer 40 is a single-layer or multilayer metal layer containing, for example, copper, gold, silver, tungsten, aluminum, titanium, iron, nickel, and / or an iron-nickel alloy. The thickness of the intermediate metal layer 40 is preferably greater than or equal to the skin thickness of the electromagnetic waves to be shielded, for example, 1 μm to 40 μm. The outer metal layer 35 is a single-layer or multilayer metal layer containing, for example, a highly conductive metal such as silver, copper, gold, and / or aluminum. The thickness of the outer metal layer 35 is, for example, 1 μm to 5 μm.

[0037] Figure 3(a) is a plan view of the series and parallel resonators in Example 1, and Figure 3(b) is a cross-sectional view of another example of the series and parallel resonators. Figures 3(a) and 3(b) show examples of series and parallel resonators formed by the first elastic wave element 50a, but the same applies to series and parallel resonators formed by the second elastic wave element 50b.

[0038] As shown in Figure 3(a), the series resonator and parallel resonator are, for example, surface acoustic wave resonators, and the first piezoelectric layer 14 has an IDT (Interdigital A transducer 51 and a reflector 52 are provided. The IDT 51 has a pair of opposing comb-shaped electrodes 53. Each comb-shaped electrode 53 has a plurality of electrode fingers 54 and a busbar 55 to which the plurality of electrode fingers 54 are connected. The plurality of electrode fingers 54 excite elastic waves in the first piezoelectric layer 14. The reflector 52 is provided on both sides of the IDT 51 and reflects the elastic waves excited by the electrode fingers 54. The pitch of the electrode fingers 54 of one of the pair of comb-shaped electrodes 53 is approximately equal to the wavelength λ of the elastic wave. Approximately twice the average pitch D of the plurality of electrode fingers 54 is approximately equal to the wavelength λ of the elastic wave. The average pitch D can be calculated by dividing the length of the IDT 51 in the direction of the arrangement of the electrode fingers 54 by the number of electrode fingers 54. The IDT 51 and the reflector 52 are formed from a metal film such as aluminum, copper, or molybdenum.

[0039] As shown in Figure 3(b), the series and parallel resonators may be piezoelectric thin-film resonators, comprising a first piezoelectric layer 14a provided on a first substrate 10, and a lower electrode 56 and an upper electrode 57 provided so as to sandwich the first piezoelectric layer 14a. An air gap 58 is formed between the lower electrode 56 and the first substrate 10. The region where the lower electrode 56 and the upper electrode 57 face each other, with at least a portion of the first piezoelectric layer 14a in between, is the resonance region 59. In the resonance region 59, the lower electrode 56 and the upper electrode 57 excite elastic waves in the first piezoelectric layer 14a. The lower electrode 56 and the upper electrode 57 are metal films, such as a ruthenium film. The first piezoelectric layer 14a is, for example, an aluminum nitride layer, a zinc oxide layer, a single-crystal lithium tantalate layer, or a single-crystal lithium niobate layer. Instead of the air gap 58, an acoustic reflective film that reflects elastic waves may be provided.

[0040] Figure 3(c) is a plan view of the DMS filter 80 in Embodiment 1. As shown in Figure 3(c), an input IDT 51a, an output IDT 51b, and a pair of reflectors 52 are provided on the second piezoelectric layer 24. The input IDT 51a is connected to the antenna terminal Ant. The output IDT 51b is connected to the receiving terminal Rx. The input IDT 51a and output IDT 51b, like the IDT 51 in Figure 3(a), are equipped with a pair of comb-shaped electrodes 53 having a plurality of electrode fingers 54 and a busbar 55. The input IDT 51a and output IDT 51b are arranged alternately in the direction in which the plurality of electrode fingers 54 are arranged. The reflectors 52 are provided so as to sandwich the input IDT 51a and output IDT 51b together from the direction in which the plurality of electrode fingers 54 are arranged. The elastic waves excited by the input IDT 51a and output IDT 51b are reflected by the reflectors 52. As a result, the energy of the elastic wave is confined within the input IDT51a and output IDT51b. A bandpass filter is formed using the two vibration modes, first and third order, generated by the acoustic coupling between input IDT51a and output IDT51b. The number of input IDT51a and output IDT51b can be set as appropriate.

[0041] [Comparative Example] Figures 4(a) and 4(b) are cross-sectional views of the elastic wave device 500 according to the comparative example. Figure 4(a) is a schematic cross-sectional view showing the portion related to the connection to the ground terminal, and Figure 4(b) is a schematic cross-sectional view showing the portion related to the connection to the signal terminal. Figure 5(a) is a plan view of the second substrate 20 in the comparative example, Figure 5(b) is a plan view of the intermediate metal layer 40, and Figure 5(c) is a plan view of the first substrate 10.

[0042] As shown in Figures 4(a), 4(b), and 5(a) to 5(c), in the comparative example, the intermediate metal layer 40 does not have a slit 46. The intermediate metal layer 40 has annular through holes 43 not only around the connection portion 44 to which the metal portion 25a of the second substrate 20 is connected, but also around the connection portion 45 to which the metal portion 25b is connected. The bottom metal layer 30 has annular through holes 33 surrounding the portion to which the metal portion 15b of the first substrate 10 is connected. Therefore, the second elastic wave element 50b provided on the second substrate 20 is electrically connected to the ground terminals Gnd1 and Gnd3 via the metal portion 25b, metal portion 19, metal portion 15b, and metal portion 32b. The other configurations are the same as in Example 1, so their description is omitted.

[0043] [simulation] In Example 1 and the Comparative Example, the pass characteristics from the antenna terminal Ant to the receiving terminal Rx were simulated. Figure 6(a) shows the simulation results of the attenuation amount with respect to frequency in Example 1 and the Comparative Example, and Figure 6(b) is an enlarged view of the vicinity of the passband in Figure 6(a). As shown in Figure 6(a), in both Example 1 and the Comparative Example, an attenuation pole was generated on the high-frequency side of the passband, but in Example 1, the attenuation pole shifted to the lower frequency side compared to the Comparative Example. The reason why the attenuation pole shifted to the lower frequency side in Example 1 is thought to be as follows. In Example 1, as shown in Figures 2(a) to 2(c), a slit 46 is provided in the intermediate metal layer 40 so as to surround the connection portion 45 in which the metal part 25b for connecting the DMS filter 80 to the ground terminals Gnd1 to Gnd4 is connected to the intermediate metal layer 40 from three directions. In this case, the DMS filter 80 is connected to the ground terminals Gnd1 to Gnd4 by the path shown by the arrow in Figure 2(b), so it is thought that the electrical length from the ground terminals Gnd1 to Gnd4 becomes longer. In other words, the inductance between the DMS filter 80 and ground is thought to increase. For this reason, it is thought that the attenuation pole shifted to the lower frequency side in Example 1. Since the attenuation pole shifted to the lower frequency side in Example 1 compared to the comparative example, it is thought that the amount of attenuation at points far below the passband on the lower frequency side was improved, as shown in Figure 6(b).

[0044] As described in Patent Document 4 (Japanese Patent Publication No. 2013-118584) above, the frequency at which an attenuation pole is generated changes depending on the inductance between the DMS filter 80 and ground. Since the frequency at which an attenuation pole should be generated changes depending on the frequency band in which the amount of attenuation is to be increased, a configuration that allows for easy adjustment of the inductance is desirable. In Example 1, the inductance between the DMS filter 80 and ground can be adjusted by adjusting the length of the slit 46 provided in the intermediate metal layer 40.

[0045] [Differentiation] Figure 7(a) is a plan view of the intermediate metal layer 40 in Modification 1 of Example 1. As shown in Figure 7(a), in Modification 1 of Example 1, the slit 46 has an I-shape along the side 41c. The other configurations are the same as in Example 1, so their explanation is omitted.

[0046] Figure 7(b) is a plan view of the intermediate metal layer 40 in Modification 2 of Example 1. As shown in Figure 7(b), in Modification 2 of Example 1, the slit 46 has an L-shape and surrounds the connecting portion 45 to which the metal part 25b connects from two directions. The other configurations are the same as in Example 1, so their explanation is omitted.

[0047] According to Example 1 and its modified form, as shown in Figures 1(a) and 1(b), a second substrate 20 having a second elastic wave element 50b is provided on a first substrate 10 having a first elastic wave element 50a on its upper surface 11 (first surface) and ground terminals Gnd1 to Gnd4 on its lower surface 12 (second surface). An intermediate metal layer 40 is provided between the first elastic wave element 50a and the second elastic wave element 50b. As shown in Figures 2(b), 2(c), 7(a), and 7(b), the intermediate metal layer 40 has a connection portion 45 to which a metal portion 25b provided on the second substrate 20 is connected, which is electrically connected to at least the second elastic wave element 50b, and a slit 46 between the connection portion 45 and the side surface 13c (first side surface) of the four side surfaces 13a to 13d of the first substrate 10 that is closest to the connection portion 45. As shown in Figures 1(a), 2(b), and 2(c), an outer metal layer 35 is provided connecting the intermediate metal layer 40 and the ground terminals Gnd1 to Gnd4, extending from all four sides 13a to 13d of the first substrate 10 to the annular metal layer 60 provided between the first substrate 10 and the second substrate 20. With this configuration, the inductance between the second elastic wave element 50b and the ground terminals Gnd1 to Gnd4 can be adjusted by adjusting the length and shape of the slit 46. Therefore, the inductance between the second elastic wave element 50b and the ground terminals Gnd1 to Gnd4 can be easily adjusted.

[0048] From the viewpoint of increasing the inductance between the second elastic wave element 50b and the ground terminals Gnd1 to Gnd4, the length L1 of the slit 46 along the side 41c of the intermediate metal layer 40 (in other words, the length L1 of the slit 46 along the side surface 13c of the first substrate 10) is preferably at least twice, more preferably at least four times, and even more preferably at least six times, the maximum length L2 of the connection portion 45 of the metal part 25b.

[0049] Furthermore, in the modified example 2 of Embodiment 1, as shown in Figure 7(b), the slit 46 provided in the intermediate metal layer 40 is provided so as to surround the connection portion 45 of the metal part 25b from two directions. That is, the slit 46 is provided so as to block the space between two of the four sides 13a to 13d of the first substrate 10, namely sides 13b and 13c, and the connection portion 45. This allows the inductance between the second elastic wave element 50b and the ground terminals Gnd1 to Gnd4 to be adjusted to be larger, and the range of adjustment can be increased.

[0050] Furthermore, in Embodiment 1, as shown in Figure 2(b), the slits 46 provided in the intermediate metal layer 40 surround the connection portion 45 of the metal part 25b from three directions. That is, the slits 46 are provided so as to block the space between three of the four sides 13a to 13d of the first substrate 10 and the connection portion 45. This allows the inductance between the second elastic wave element 50b and the ground terminals Gnd1 to Gnd4 to be adjusted to be larger, and the range of adjustment can be increased.

[0051] Furthermore, in Example 1 and Modification 2 of Example 1, as shown in Figures 2(b) and 7(b), the slit 46 has a first portion 47 whose longitudinal direction is in the direction along side 41c, and a second portion 48 whose longitudinal direction is in the direction along sides 41b and 41d that intersect side 41c. In other words, the slit 46 has a first portion 47 whose longitudinal direction is in the direction along side surface 13c (first side surface) of the first substrate 10, and a second portion 48 whose longitudinal direction is in the direction along sides 13b and 13d (second side surfaces) that intersect side surface 13c. The second portion 48 is provided from the first portion 47 to beyond the midpoints 42a and 42b of sides 41b and 41d. In other words, the second portion 48 is provided from the first portion 47 to beyond the center of sides 13b and 13d. This allows the inductance between the second elastic wave element 50b and the ground terminals Gnd1 to Gnd4 to be adjusted to be larger.

[0052] Furthermore, in Example 1 and its modified form, the annular metal layer 60 is rectangular in plan view, as shown in Figure 2(b). The intermediate metal layer 40 is connected to all sides 61a to 61d of the annular metal layer 60. This strengthens the ground potential of the intermediate metal layer 40.

[0053] Furthermore, in Example 1 and its modified form, as shown in Figure 2(c), a ladder-type filter 81 having series resonators S11 and S12 and a parallel resonator P11 is formed by a first elastic wave element 50a provided on the first substrate 10. As shown in Figure 2(a), a series resonator S21 and a parallel resonator P21 and a DMS filter 80 connected thereto are formed by a second elastic wave element 50b provided on the second substrate 20. In this case, the inductance between the DMS filter 80 and ground terminals Gnd1 to Gnd4 can be adjusted by a slit 46 provided in the intermediate metal layer 40, thereby adjusting the position of the attenuation pole in the pass-through characteristics of the DMS filter 80, as shown in Figure 6(a).

[0054] In Example 1 and its modified form, the inductance between the DMS filter 80 and the ground terminals Gnd1 to Gnd4 is adjusted by a slit 46 provided in the intermediate metal layer 40, but the method is not limited to this case. The inductance between the parallel resonator and the ground terminal may also be adjusted. [Examples]

[0055] Figures 8(a) and 8(b) are cross-sectional views of the elastic wave device 200 according to Embodiment 2. Figure 8(a) is a schematic cross-sectional view showing the portion related to the connection to the ground terminal, and Figure 8(b) is a schematic cross-sectional view showing the portion related to the connection to the signal terminal. Figure 9(a) is a plan view of the second substrate 20 in Embodiment 2, Figure 9(b) is a plan view of the intermediate metal layer 40, and Figure 9(c) is a plan view of the first substrate 10.

[0056] As shown in Figures 8(a), 8(b), and 9(a) to 9(c), in Embodiment 2, a metal part 19a is provided on the first substrate 10, electrically connected to ground terminals Gnd1 to Gnd4 via a metal part 15b, a lower metal layer 30, and a metal part 32b. The metal part 19a is connected to an intermediate metal layer 40. The portion where the metal part 19a connects to the intermediate metal layer 40 is called the connection portion 49. The slit 46a provided in the intermediate metal layer 40 encloses both the connection portion 45 to which the metal part 25b connects and the connection portion 49 to which the metal part 19a connects in a plan view. The region enclosed by the slit 46a is, for example, spiral-shaped in a plan view, and as an example, it is a rectangular spiral. The connection portion 45 is located at one end of the spiral region, and the connection portion 49 is located at the other end. The other configurations are the same as in Embodiment 1, so their description is omitted.

[0057] According to Embodiment 2, as shown in Figures 8(a) and 8(b), a second substrate 20 having a second elastic wave element 50b is provided on a first substrate 10 having a first elastic wave element 50a on its upper surface 11 (first surface) and ground terminals Gnd1 to Gnd4 on its lower surface 12 (second surface). An intermediate metal layer 40 is provided between the first elastic wave element 50a and the second elastic wave element 50b. The first substrate 10 is provided with a metal part 15b (first metal part) that penetrates from the upper surface 11 to the lower surface 12 and is electrically connected to the ground terminal Gnd3, and a metal part 19a (second metal part) on the upper surface 11 that is electrically connected to the metal part 15b. As shown in Figure 9(a), the second substrate 20 is provided with a metal part 25b (third metal part) that is electrically connected to the second elastic wave element 50b. As shown in Figure 9(b), the intermediate metal layer 40 has a slit 46a that, in a plan view, encloses both the connection portion 49 (first connection portion) to which the metal portion 19a is connected and the connection portion 45 (second connection portion) to which the metal portion 25b is connected. This allows the inductance between the second elastic wave element 50b and the ground terminal Gnd3 to be adjusted by adjusting the distance between the connection portion 45 and the connection portion 49 in the region enclosed by the slit 46a. Thus, the inductance between the second elastic wave element 50b and the ground terminal Gnd3 can be easily adjusted.

[0058] Furthermore, according to Embodiment 2, as shown in Figure 9(b), the region enclosed by the slit 46a is vortex-shaped in a plan view. The connection portion 49 to which the metal part 19a connects is located at one end of the vortex-shaped region, and the connection portion 45 to which the metal part 25b connects is located at the other end. This makes it easy to adjust the inductance between the second elastic wave element 50b and the ground terminal Gnd3 to be large. [Examples]

[0059] Figure 10 is a cross-sectional view of the elastic wave device 300 according to Embodiment 3. As shown in Figure 10, in Embodiment 3, the second substrate 20 is provided on the first substrate 10 such that the second elastic wave element 50b faces the first elastic wave element 50a. That is, the second piezoelectric layer 24 is bonded to the lower surface 22 of the second substrate 20, and the second elastic wave element 50b is provided on the lower surface 22 of the second substrate 20. The first elastic wave element 50a and the second elastic wave element 50b are sealed in the gap 38 formed between the first substrate 10 and the second substrate 20 by annular metal layers 60 and 70. The intermediate metal layer 40 is sandwiched between the annular metal layer 60 and the annular metal layer 70 and provided between the first elastic wave element 50a and the second elastic wave element 50b. A metal portion 25c connected to the intermediate metal layer 40 is provided on the lower surface 22 of the second substrate 20. Therefore, the second elastic wave element 50b is electrically connected to the ground terminals Gnd1 to Gnd4 via the metal part 25c, the intermediate metal layer 40, the annular metal layers 60 and 70, the outer metal layer 35, the bottom metal layer 30, and the metal part 32b. The other configurations are the same as in Example 1, so they are not shown or described.

[0060] In Example 1 and its modified form, as well as in Example 2, the second elastic wave element 50b is provided on the upper surface 21 (the surface opposite to the first substrate 10) of the second substrate 20, and the metal part 25b electrically connected to the second elastic wave element 50b is provided penetrating the second substrate 20. However, the example is not limited to this case, and as in Example 3, the second elastic wave element 50b may be provided on the lower surface 22 (the surface on the first substrate 10 side) of the second substrate 20, and the metal part 19a electrically connected to the second elastic wave element 50b may be provided on the lower surface 22 of the second substrate 20. In Example 3, the configuration is the same as in Example 1 except that the first elastic wave element 50a and the second elastic wave element 50b are arranged facing each other, but the configuration may also be the same as in Example 2.

[0061] Although 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 changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of Symbols]

[0062] 10…First substrate, 11…Top surface, 12…Bottom surface, 13a~13d…Side, 14, 14a…First piezoelectric layer, 15a, 15b…Metal part, 16…Wiring, 18…Gap, 19, 19a…Metal part, 20…Second substrate, 21…Top surface, 22…Bottom surface, 24…Second piezoelectric layer, 25a, 25b, 25c…Metal part, 26…Wiring, 27…Insulating film, 28…Gap, 30…Bottom metal layer, 31…Insulating film, 32a, 32b…Metal part, 33…Through hole, 34…Lid, 35…Outer metal layer, 38…Gap, 40…Intermediate metal layer, 41a~41d…Edge, 42a, 42b…Midpoint, 43…Through hole, 44…Connection part, 45…Connection part, 46, 46a …Slit, 47…First part, 48…Second part, 49…Connection part, 50a…First elastic wave element, 50b…Second elastic wave element, 51…IDT, 51a…Input IDT, 51b…Output IDT, 52…Reflector, 53…Comb electrode, 54…Electrode fingers, 55…Busbar, 56…Lower electrode, 57…Upper electrode, 58…Air gap, 59…Resonant region, 60…Annular metal layer, 61a~61d…Edges, 70…Annular metal layer, 80…DMS filter, 81…Ladder filter, 100, 200, 300, 500…Elastic wave device, Ant…Antenna terminal, Tx…Transmitting terminal, Rx…Receiver terminal, Gnd1~Gnd4…Ground terminal

Claims

1. A first substrate having a rectangular shape in plan view, having a first surface, a second surface, and four sides connecting the first surface and the second surface, A first elastic wave element provided on the first surface, A ground terminal provided on the second surface, A second substrate is provided on the first substrate, having a gap between it and the first elastic wave element in which the first elastic wave element is exposed. The second elastic wave element provided on the second substrate, An annular metal layer is provided between the first substrate and the second substrate, surrounding the first elastic wave element, A metal portion provided on the second substrate and electrically connected to the second elastic wave element, An intermediate metal layer provided between the first elastic wave element and the second elastic wave element, having a slit provided away from the connection portion between at least the connection portion where the metal portion is connected and the first side of the four side surfaces that is closest to the connection portion, An elastic wave device comprising: an outer metal layer provided from all four sides of the first substrate across the annular metal layer, which electrically connects the intermediate metal layer and the ground terminal.

2. The elastic wave device according to claim 1, wherein the slit is provided so as to block the space between two of the four sides and the connecting portion.

3. The elastic wave device according to claim 1, wherein the slit is provided so as to block the space between three of the four sides and the connecting portion.

4. The slit has a first portion located between the first side surface and the connecting portion and having a longitudinal direction along the first side surface, and a second portion having a longitudinal direction along the second side surface intersecting the first side surface. The elastic wave device according to claim 2 or 3, wherein the second portion is provided extending from the first portion to beyond the center of the second side surface.

5. The aforementioned annular metal layer is rectangular in plan view, The elastic wave device according to any one of claims 1 to 3, wherein the intermediate metal layer is connected to all sides of the annular metal layer.

6. The second elastic wave element is provided on the surface of the second substrate opposite to the first substrate, The elastic wave device according to any one of claims 1 to 3, wherein the metal portion is provided penetrating the second substrate.

7. The second elastic wave element is provided on the surface of the second substrate that is on the side of the first substrate, The elastic wave device according to any one of claims 1 to 3, wherein the metal part is provided on the surface of the first substrate.

8. A first substrate having a rectangular shape in plan view, having a first surface, a second surface, and four sides connecting the first surface and the second surface, A first elastic wave element provided on the first surface, A ground terminal provided on the second surface, A first metal portion extends from the first surface to the second surface through the first substrate and is electrically connected to the ground terminal, A second metal part provided on the first surface and electrically connected to the first metal part, A second substrate is provided on the first substrate, having a gap between it and the first elastic wave element in which the first elastic wave element is exposed. The second elastic wave element provided on the second substrate, An annular metal layer is provided between the first substrate and the second substrate, surrounding the first elastic wave element, A third metal portion provided on the second substrate and electrically connected to the second elastic wave element, An elastic wave device comprising: an intermediate metal layer provided between the first elastic wave element and the second elastic wave element, having a slit that, in a plan view, collectively surrounds the first connecting portion to which the second metal part is connected and the second connecting portion to which the third metal part is connected.

9. In a plan view, the region enclosed by the slit is spiral-shaped. The elastic wave device according to claim 8, wherein the first connecting portion is located at one end of the vortex region, and the second connecting portion is located at the other end.

10. A first elastic wave filter is formed by the first elastic wave element. The elastic wave device according to claim 1 or 8, wherein a second elastic wave filter is formed by the second elastic wave element.

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