Elastic wave device

Abstract

An elastic wave device 10 according to the present invention comprises: an elastic wave element 1; a package substrate 12 on which is mounted an elastic wave element 1 formed from a stacked plurality of package layers (first to sixth package layers 12a-12f) each having two main surfaces opposing each other; a first inductor L1 provided on one of the main surfaces of one of the plurality of package layers; a first electrode pattern M1 provided on a main difference different from the main surface on which the first inductor L1 is provided from among the plurality of main surfaces of the plurality of package layers; and a first through electrode connecting the first inductor L1 and the first electrode pattern M1 and penetrating through at least one package layer. When seen in a plan view, the first inductor L1 and the first electrode pattern M1 having overlapping paths from a start point to an end point. The width of the first electrode pattern M1 is narrower than the width of an electrode pattern constituting the first inductor L1.

Description

Elastic Wave Device

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

[0002] Conventionally, acoustic wave devices have been widely used in filters for mobile phones and the like. Patent Document 1 below discloses an example of an acoustic wave device. This acoustic wave device has a circuit board and an acoustic wave element provided on the circuit board. The circuit board is a laminated board of multiple dielectric layers. An inductor is provided within the circuit board. The inductor is composed of multiple wirings. The wirings that make up the inductor face each other with a dielectric layer sandwiched between them.

[0003] Japanese Patent Application Laid-Open No. 2020-127089

[0004] In reality, misalignment of wiring may occur during the manufacture of an acoustic wave device. If misalignment of wiring constituting an inductor occurs, when the acoustic wave device is used in a filter device, there is a risk that variations in attenuation characteristics outside the passband may increase.

[0005] An object of the present invention is to provide an acoustic wave device that can reduce variations in attenuation characteristics outside the passband in a filter device.

[0006] An elastic wave device according to the present invention comprises an elastic wave element, a package substrate on which the elastic wave element is mounted, the package substrate being formed by stacking a plurality of package layers, each having two main surfaces facing each other, a first inductor provided on one of the main surfaces of one of the plurality of package layers, a first electrode pattern provided on one of the main surfaces of the plurality of package layers other than the main surface on which the first inductor is provided, and a first through electrode connecting the first inductor and the first electrode pattern and penetrating at least one of the package layers, wherein, when viewed in a plane, the first inductor and the first electrode pattern overlap on paths from a start point to an end point, and the width of the first electrode pattern is narrower than the width of the electrode pattern constituting the first inductor.

[0007] According to an acoustic wave device according to a preferred embodiment of the present invention, it is possible to reduce variations in attenuation characteristics outside the passband in a filter device.

[0008] FIG. 1 is a schematic front cross-sectional view of an elastic wave device according to a first preferred embodiment of the present invention. FIG. 2 is a schematic plan view illustrating a first inductor and other components provided on a first main surface of a fourth package layer according to the first preferred embodiment of the present invention. FIGS. 3A to 3C are schematic views for explaining the shape of an inductor according to the preferred embodiment of the present invention. FIG. 4 is a schematic plan view illustrating a first inductor and a first electrode pattern and other components provided on each main surface of a third package layer according to the first preferred embodiment of the present invention. FIG. 5 is a schematic perspective view illustrating the vicinity of the first inductor and the first electrode pattern according to the first preferred embodiment of the present invention. FIG. 6 is a schematic bottom view illustrating the electrode configuration of an elastic wave resonator according to the first preferred embodiment of the present invention. FIG. 7 is a schematic front cross-sectional view of an elastic wave device according to a modified preferred embodiment of the first preferred embodiment of the present invention. FIG. 8 is a schematic plan view illustrating the vicinity of each inductor and each electrode pattern provided on each main surface of a third package layer according to the second preferred embodiment of the present invention. FIG. 9 is a schematic cross-sectional view showing the vicinity of each inductor and each electrode pattern in a cross section passing through each inductor and each electrode pattern in a second embodiment of the present invention. FIG. 10 is a schematic cross-sectional view showing the vicinity of each inductor and each electrode pattern in a cross section passing through each inductor and each electrode pattern in a modification of the second embodiment of the present invention. FIG. 11 is a diagram showing attenuation-frequency characteristics in the second embodiment of the present invention. FIG. 12 is a diagram showing attenuation-frequency characteristics in the modification of the second embodiment of the present invention. FIG. 13(a) is a schematic diagram showing a case where the misalignment amount in each inductor and each electrode pattern in the second embodiment of the present invention is 0 μm. FIG. 13(b) is a schematic diagram showing a case where the misalignment amount in each inductor and each electrode pattern in the second embodiment of the present invention is greater than 0 μm. FIG. 14 is a schematic front cross-sectional view of an acoustic wave device in a third embodiment of the present invention. FIG. 15 is a schematic bottom view showing the electrode configuration of an acoustic wave resonator in a fourth embodiment of the present invention. FIG. 16 is a diagram showing the relationship between d / p and the fractional bandwidth of an acoustic wave resonator. 17 is a graph showing the relationship between the bandwidth ratio and the normalized magnitude of spurious signals in an acoustic wave resonator, and FIG. 18 is a graph showing the relationship between d / p, the metallization ratio MR, and the bandwidth ratio.FIG. 19 shows LiNbO when d / p approaches 0. ３ FIG. 10 is a diagram showing a map of fractional bandwidths versus Euler angles (0°, θ, ψ) of the .lambda.

[0009] The present invention will be clarified below by describing specific embodiments of the present invention with reference to the drawings.

[0010] It should be noted that the embodiments described in this specification are merely examples, and partial substitution or combination of configurations is possible between different embodiments.

[0011] 1 is a schematic front cross-sectional view of an elastic wave device according to a first preferred embodiment of the present invention, in which an IDT (Interdigital Transducer) electrode (described later) is shown as a simplified rectangle with two diagonal lines added.

[0012] The acoustic wave device 10 of this embodiment is a filter device. In this specification, the term "filter device" refers to a bandpass filter having one passband, a composite filter device such as a multiplexer, and the like. The acoustic wave device 10 includes an acoustic wave element 1 and a package substrate 12. The acoustic wave element 1 is an acoustic wave filter chip. The acoustic wave element 1 includes multiple resonators. More specifically, the multiple resonators in this embodiment are all acoustic wave resonators 11. FIG. 1 shows one acoustic wave resonator 11.

[0013] A plurality of acoustic wave resonators 11 share a piezoelectric substrate 2. The piezoelectric substrate 2 is a substrate having piezoelectric properties. The piezoelectric substrate 2 is a laminated substrate including a piezoelectric layer 4 made of a piezoelectric material. Each acoustic wave resonator 11 has an IDT electrode 7. Each acoustic wave resonator 11 is configured by providing the IDT electrode 7 on the piezoelectric substrate 2.

[0014] The elastic wave device of the present invention may include at least one elastic wave resonator. For example, the elastic wave element may be an element chip including only one elastic wave resonator. The elastic wave device of the present invention may be used in a filter device together with other resonators.

[0015] As shown in FIG. 1 , the acoustic wave element 1 is mounted on a package substrate 12. Specifically, in this embodiment, the acoustic wave element 1 is flip-chip mounted on the package substrate 12. The acoustic wave device 10 has a chip size package (CSP) structure. The acoustic wave element 1 is electrically connected to the outside via wiring provided on the package substrate 12. However, in the acoustic wave device according to the present invention, an acoustic wave element having a wafer level package (WLP) structure may be mounted on the package substrate.

[0016] In this embodiment, a sealing resin layer 17 is provided on package substrate 12 so as to cover acoustic wave element 1. Note that sealing resin layer 17 does not necessarily have to be provided.

[0017] The package substrate 12 is a laminated substrate in which multiple package layers are stacked. Specifically, the package substrate 12 has six package layers. More specifically, the package substrate 12 has a first package layer 12a, a second package layer 12b, a third package layer 12c, a fourth package layer 12d, a fifth package layer 12e, and a sixth package layer 12f stacked in this order. However, the number of layers in the package substrate 12 may be two or more.

[0018] Each of the multiple package layers has a first main surface and a second main surface. In each package layer, the first main surface faces the acoustic wave device 1. The first main surface 13a of the first package layer 12a is one of the outermost main surfaces of the package substrate 12. The second main surface 14f of the sixth package layer 12f is the other of the outermost main surfaces of the package substrate 12.

[0019] The acoustic wave element 1 is mounted on a first main surface 13a of the first package layer 12a. As described above, of the multiple package layers in the package substrate 12, the first package layer 12a is located closest to the acoustic wave element 1. The second package layer 12b to the sixth package layer 12f are stacked in a direction away from the acoustic wave element 1. The materials for each package layer may be, for example, glass epoxy resin or appropriate ceramics.

[0020] A first inductor L1 is provided on the package substrate 12. The first inductor L1 is made up of an electrode pattern. Specifically, the first inductor L1 is provided between the third package layer 12c and the fourth package layer 12d. More specifically, the first inductor L1 is made up of an electrode pattern provided on the first main surface 13d of the fourth package layer 12d. The electrode pattern constituting the first inductor L1 is embedded in the third package layer 12c from the second main surface 14c of the third package layer 12c.

[0021] In this specification, an electrode pattern or a wiring pattern embedded in one of the main surfaces of a package layer from the package layer is also considered to be an electrode pattern or a wiring pattern provided on the main surface. The electrode pattern constituting the first inductor L1 shown in FIG. 1 can also be said to be provided on the second main surface 14 c of the third package layer 12 c.

[0022] The position where the first inductor L1 is provided is not limited to the above. The electrode pattern constituting the first inductor L1 may be provided on one main surface of any one of the multiple package layers.

[0023] A first electrode pattern M1 is provided on the package substrate 12. Specifically, the first electrode pattern M1 is provided between the second package layer 12b and the third package layer 12c. The first electrode pattern M1 is provided on the first main surface 13c of the third package layer 12c. As shown in FIG. 1 , the first inductor L1 and the first electrode pattern M1 are provided on one main surface and the other main surface of the same package layer. It can also be said that the first electrode pattern M1 is provided on the second main surface 14b of the second package layer 12b.

[0024] The first inductor L1 and the first electrode pattern M1 overlap in a plan view. In this specification, a plan view refers to viewing the acoustic wave device from a direction corresponding to the top in Fig. 1 or the like. For example, in Fig. 1, the piezoelectric substrate 2 side is the top of the package substrate 12 side. On the other hand, in this specification, a bottom view refers to viewing the acoustic wave device from a direction corresponding to the bottom in Fig. 1 or the like.

[0025] FIG. 2 is a schematic plan view showing a first inductor and other components provided on a first main surface of a fourth package layer in the first embodiment.

[0026] The first inductor L1 has a start point 19a, an end point 19b, multiple corner portions 19c, and multiple wiring portions 19d. The start point 19a and the end point 19b are configured as electrode pads. Each wiring portion 19d connects the start point 19a to the corner portion 19c, the corner portions 19c to each other, or the corner portion 19c to the end point 19b. The dashed-dotted lines in FIG. 2 indicate the boundary between the start point 19a and the wiring portion 19d, and the boundary between the end point 19b and the wiring portion 19d.

[0027] In this embodiment, the shapes of the starting point 19a and the ending point 19b in a planar view are shapes in which an arc and a straight line are connected. In a planar view, the shape of the boundary between the starting point 19a and the wiring portion 19d, and the shape of the boundary between the ending point 19b and the wiring portion 19d are linear. The shape of each corner portion 19c in a planar view includes a curved shape. The shape of each wiring portion 19d in a planar view includes only linear shapes. Specifically, the shape of each wiring portion 19d in a planar view is rectangular. The shape of the path from the starting point 19a to the ending point 19b is a spiral shape.

[0028] The shape of each portion of the first inductor L1 in a plan view and the shape of the path from the starting point 19a to the ending point 19b are not limited to those described above. For example, the shapes of the starting point 19a and the ending point 19b in a plan view may be polygonal. The shape of at least one corner portion 19c in a plan view may include only linear shapes. The shape of at least one wiring portion 19d in a plan view may include curved shapes. The shape of the inductor in the present invention will be described in more detail below with reference to FIGS. 3(a) to 3(c).

[0029] 3(a) to 3(c) are schematic diagrams illustrating the shape of the inductor according to the present invention. The dashed-dotted lines in Fig. 3(a) to 3(c) indicate the shortest route from start point 19a to end point 19b. Note that the shortest route is the range that includes all line segments connecting start point 19a and end point 19b.

[0030] In the present invention, an inductor includes a path other than the shortest path that includes the starting point 19 a and the ending point 19 b. For example, a linear electrode pattern connecting the starting point 19 a and the ending point 19 b does not include a path other than the shortest path that includes the starting point 19 a and the ending point 19 b. Therefore, this linear electrode pattern is not an inductor in the present invention.

[0031] 3(a) to 3(c) are examples of inductors according to the present invention. Inductor La shown in Fig. 3(a) has one corner 19c. In inductor La, corner 19c is located outside the shortest path that includes starting point 19a and ending point 19b.

[0032] More specifically, starting point 19a and corner 19c are connected by linear wiring portion 19d. Corner 19c and end point 19b are connected by another linear wiring portion 19d. The direction from starting point 19a toward corner 19c is different from the direction from corner 19c toward end point 19b. Therefore, in the path of inductor La from starting point 19a to end point 19b, the direction in which the electrode pattern constituting inductor La extends is switched at one corner 19c.

[0033] 3B, the inductor Lb has two corner portions 19c. The two corner portions 19c are located outside the shortest path that includes the starting point 19a and the ending point 19b. The starting point 19a and the corner portion 19c, the corner portions 19c, and the corner portion 19c and the ending point 19b are connected by linear wiring portions 19d.

[0034] 3(c), a starting point 19a and an end point 19b are connected by a curved wiring portion 19e. A portion of the wiring portion 19e is located outside the shortest path that includes the starting point 19a and the end point 19b. Therefore, in the inductor Lc, the path from the starting point 19a to the end point 19b includes a path other than the shortest path that includes the starting point 19a and the end point 19b. The description of the first embodiment continues below.

[0035] Fig. 4 is a schematic plan view showing the first inductor and the first electrode pattern provided on each main surface of the third package layer in the first embodiment. Fig. 5 is a schematic perspective view showing the first inductor and the first electrode pattern and their vicinity in the first embodiment. Note that in Fig. 5, the first inductor L1 and the first electrode pattern M1 are indicated by hatching. In Fig. 5, the package substrate 12 and the like are omitted.

[0036] As shown in FIG. 4 , the shape of the first electrode pattern M1 in a plan view is substantially the same as the shape of the first inductor L1 in a plan view. More specifically, like the first inductor L1, the first electrode pattern M1 has a starting point 18a and an ending point 18b, multiple corner portions 18c, and multiple wiring portions 18d. Each wiring portion 18d connects the starting point 18a to the corner portion 18c, the corner portions 18c to each other, or the corner portion 18c to the ending point 18b. The shape of the path from the starting point 18a to the ending point 18b is a spiral. In a plan view, the path from the starting point 18a to the ending point 18b of the first electrode pattern M1 overlaps with the path from the starting point 19a to the ending point 19b of the first inductor L1.

[0037] In this specification, a configuration in which two electrode patterns overlap in paths from the start point to the end point when viewed in a plan view is as follows. That is, this configuration refers to a configuration in which, when viewed in a plan view, at least a portion in the width direction of one electrode pattern overlaps with the path of the other electrode pattern over the entire path of the electrode pattern. In this configuration, the two electrode patterns have the same number of locations that include corner portions and wiring portions. Note that, in this specification, the width direction of the electrode patterns refers to the direction perpendicular to the direction in which the electrode patterns extend. The width of the electrode patterns is the dimension along the width direction of the electrode patterns.

[0038] In the first embodiment, the width of the first electrode pattern M1 is narrower than the width of the first inductor L1. In plan view, a portion of the first inductor L1 in the width direction does not overlap with the first electrode pattern M1. This case also falls under the category of two electrode patterns overlapping on paths from the start point to the end point in plan view.

[0039] In the first embodiment, in a plan view, the entire narrower electrode pattern overlaps with the wider electrode pattern. However, for example, in a plan view, a portion of the narrower electrode pattern in the width direction may overlap with the path of the other electrode pattern over the entire path of the electrode pattern. In addition, in a plan view, another portion of the narrower electrode pattern in the width direction may not overlap with the path of the other electrode pattern over at least a portion of the path of the electrode pattern. This case is also included in the configuration in which the two electrode patterns overlap over paths from the start point to the end point when viewed in a plan view.

[0040] As shown in Fig. 5, the first inductor L1 and the first electrode pattern M1 are connected by a first through electrode 24A. The first through electrode 24A penetrates the third package layer 12c shown in Fig. 1. As shown in Fig. 5, the start points of the first inductor L1 and the first electrode pattern M1 are connected by the first through electrode 24A. The end points of the first inductor L1 and the first electrode pattern M1 are connected by another first through electrode 24A.

[0041] In the elastic wave device 10 shown in FIG. 1 , an electrical signal passes through at least a portion of the elastic wave element 1 and then through the first electrode pattern M1 and the first inductor L1. The electrical signal flows from the starting point 18 a to the ending point 18 b of the first electrode pattern M1 shown in FIG. 4 . In this embodiment, the starting points and ending points of the first electrode pattern M1 and the first inductor L1 are connected to each other. This allows the electrical signal to flow from the starting point 19 a to the ending point 19 b in the first inductor L1 as well. In this way, even if the first inductor L1 and the first electrode pattern M1 have substantially the same shape in a planar view, the current can flow in the same direction. This allows the first inductor L1 and the first electrode pattern M1 to be electromagnetically coupled in a suitable manner.

[0042] A feature of the present invention is that, in a plan view, the first inductor L1 and the first electrode pattern M1 overlap along paths from the start point to the end point, and the width of the first electrode pattern M1 is narrower than the width of the electrode patterns constituting the first inductor L1. This makes it possible to suppress variations in the attenuation characteristics outside the passband in the elastic wave device 10 serving as a filter device, as described below.

[0043] The attenuation characteristics outside the passband of a filter device are affected by electromagnetic coupling between electrode patterns. The strength of the electromagnetic coupling between electrode patterns varies depending on the relative positions of the electrode patterns. However, in reality, when manufacturing an acoustic wave device, variations in the positions of the electrode patterns may occur. Therefore, variations in the strength of the electromagnetic coupling between the electrode patterns may also occur.

[0044] In contrast, in the first embodiment, the first inductor L1 and the first electrode pattern M1 overlap along paths from the start point to the end point in a plan view, and the width of the first electrode pattern M1 is narrower than the width of the electrode pattern of the first inductor L1. Therefore, even if the position of the first electrode pattern M1 relative to the first inductor L1 shifts, the area of ​​the overlapping portion between the first inductor L1 and the first electrode pattern M1 in a plan view is unlikely to change. This reduces variations in the strength of electromagnetic coupling between the first inductor L1 and the first electrode pattern M1. This reduces variations in the attenuation characteristics outside the passband of the elastic wave device 10 as a filter device.

[0045] The configuration of the first embodiment will be described in further detail below. As shown in FIG. 1 , the piezoelectric substrate 2 of the acoustic wave element 1 is a laminated substrate. Specifically, the piezoelectric substrate 2 has a support member 3 and a piezoelectric layer 4 serving as a piezoelectric film. The piezoelectric layer 4 is a layer made of a piezoelectric material. Meanwhile, in this specification, a piezoelectric film refers to a film having piezoelectricity, and does not necessarily refer to a film made of a piezoelectric material. However, in the first embodiment, the piezoelectric film is a single-layer piezoelectric layer 4, which is a film made of a piezoelectric material. Note that in the present invention, the piezoelectric film may be a laminated film including the piezoelectric layer 4.

[0046] In the first embodiment, the support member 3 includes a support substrate 6 and an insulating layer 5. The insulating layer 5 is provided on the support substrate 6. The piezoelectric layer 4 is provided on the insulating layer 5. However, without being limited to the above, the support member 3 may be composed of only the support substrate 6. Alternatively, the support member 3 may not necessarily be provided.

[0047] The support substrate 6 may be made of a semiconductor such as silicon or a ceramic such as aluminum oxide. The insulating layer 5 may be made of an appropriate dielectric such as silicon oxide or tantalum oxide. The piezoelectric layer 4 may be made of LiNbO ３ Lithium niobate such as LiTaO ３In this specification, when a certain component is made of a certain material, it also includes the case where a trace amount of impurities is contained to the extent that the electrical characteristics of the acoustic wave device are not significantly deteriorated.

[0048] A recess is provided in the insulating layer 5. A piezoelectric layer 4 serving as a piezoelectric film is provided on the insulating layer 5 so as to close the recess. This forms a hollow portion. This hollow portion is the cavity 1a. In the first embodiment, the support member 3 and the piezoelectric film are arranged so that a portion of the support member 3 and a portion of the piezoelectric film face each other with the cavity 1a in between. However, the recess in the support member 3 may be provided across the insulating layer 5 and the support substrate 6. Alternatively, a recess provided only in the support substrate 6 may be closed by the insulating layer 5. The recess may be provided in the piezoelectric layer 4, for example. The cavity 1a may be a through-hole provided in the support member 3.

[0049] 6 is a schematic bottom view showing the electrode configuration of the acoustic wave resonator 11 according to the first preferred embodiment, in which wiring and the like connected to the acoustic wave resonator 11 are omitted.

[0050] An IDT electrode 7 is provided on a piezoelectric layer 4 serving as a piezoelectric film on the piezoelectric substrate 2. The IDT electrode 7 has a pair of bus bars and a plurality of electrode fingers. The pair of bus bars is specifically a first bus bar 15a and a second bus bar 15b. The first bus bar 15a and the second bus bar 15b face each other. The plurality of electrode fingers is specifically a plurality of first electrode fingers 16a and a plurality of second electrode fingers 16b. One ends of the plurality of first electrode fingers 16a are connected to the first bus bar 15a, respectively. One ends of the plurality of second electrode fingers 16b are connected to the second bus bar 15b, respectively. The plurality of first electrode fingers 16a and the plurality of second electrode fingers 16b are interdigitated with each other. The first electrode fingers 16a and the second electrode fingers 16b are connected to different potentials.

[0051] Hereinafter, the first electrode finger 16 a and the second electrode finger 16 b may be simply referred to as electrode fingers. The direction in which the multiple electrode fingers extend is referred to as the electrode finger extension direction, and the direction perpendicular to the electrode finger extension direction is referred to as the electrode finger perpendicular direction. When viewed from the electrode finger perpendicular direction, the region where adjacent electrode fingers overlap is referred to as an intersection region A.

[0052] The acoustic wave resonator 11 is configured to utilize thickness-shear mode bulk waves as the main mode. More specifically, when viewed from the electrode finger orthogonal direction, the region where adjacent electrode fingers overlap and the region between the centers of the adjacent electrode fingers is the excitation region C. The intersection region A includes multiple excitation regions C. In FIG. 6 , one of the multiple excitation regions C is indicated by a two-dot chain line. By applying an AC voltage to the IDT electrode 7, thickness-shear mode bulk waves are excited in each excitation region C. Note that the intersection region A and the excitation region C are regions of the piezoelectric layer 4 defined based on the configuration of the IDT electrode 7.

[0053] When the thickness of the piezoelectric film is d and the center-to-center distance between adjacent electrode fingers is p, d / p is 0.5 or less. This allows for suitable excitation of bulk waves in thickness-shear mode. In the first embodiment, the thickness d is the thickness of the piezoelectric layer 4. In the acoustic wave device 1, the acoustic wave resonators other than the acoustic wave resonator 11 shown in FIG. 1 are also configured to be capable of exciting bulk waves in thickness-shear mode.

[0054] The elastic wave resonator according to the present invention may be configured to use, for example, a plate wave as the main mode. In this case, the excitation region in elastic wave resonator 11 is crossover region A. In this case, d / p≦0.5 does not have to be satisfied.

[0055] The cavity 1a shown in Fig. 1 is the acoustic reflector of the present invention. The acoustic reflector can effectively confine the energy of the elastic wave to the piezoelectric layer 4 side. The acoustic reflector may be provided at a position on the support member 3 that overlaps with at least a portion of the IDT electrode 7 in a planar view. More specifically, at least a portion of each of the first electrode finger 16a and the second electrode finger 16b may overlap with the acoustic reflector in a planar view. It is preferable that a plurality of excitation regions C overlap with the acoustic reflector in a planar view.

[0056] However, the acoustic reflection portion may be an acoustic reflection film, which will be described later. For example, an acoustic reflection film may be provided on the surface of the support member.

[0057] A plurality of electrode pads 8 are provided on the piezoelectric layer 4 serving as a piezoelectric film. Bumps 9 serving as conductive bonding members are provided on each electrode pad 8. The bumps 9 electrically connect the acoustic wave element 1 to the package substrate 12. More specifically, as described above, a plurality of mounting electrode lands 23 are provided on the first main surface 13a of the first package layer 12a. The bumps 9 bond the electrode pads 8 of the acoustic wave element 1 to the mounting electrode lands 23 of the package substrate 12. In this way, the acoustic wave element 1 is mounted on the package substrate 12. Note that, for example, a conductive adhesive may be used as the conductive bonding member.

[0058] A plurality of wiring patterns 25 are provided within package substrate 12. More specifically, a plurality of wiring patterns 25 are provided between each of the package layers. In the first embodiment, each wiring pattern 25 is provided on the first main surface of one of the package layers and embedded in the package layer adjacent to the package layer on the side of acoustic wave device 1.

[0059] However, the wiring pattern 25 provided on the second main surface of any one of the package layers may be embedded in an adjacent package layer on the side of the package layer farther from the acoustic wave device 1. This also applies to the electrode pattern constituting the first inductor L1 and the first electrode pattern M1.

[0060] The second main surface 14f of the sixth package layer 12f is provided with a plurality of external connection electrode lands 27. The main surface on which the plurality of external connection electrode lands 27 are provided is the surface located on the outermost side of the package substrate 12.

[0061] A plurality of through electrodes 24 are provided so as to penetrate each package layer. Some of the plurality of through electrodes 24 connect the mounting electrode lands 23 and the wiring pattern 25. Other through electrodes 24 connect the wiring patterns 25 provided on different principal surfaces to each other. The remaining through electrodes 24 connect the wiring patterns 25 and the external connection electrode lands 27. The acoustic wave element 1 is electrically connected to the outside via the mounting electrode lands 23, the through electrodes 24, the wiring patterns 25, and the external connection electrode lands 27. Specifically, the acoustic wave element 1 is electrically connected to an external signal potential and a reference potential.

[0062] The first inductor L1 is electrically connected to the acoustic wave element 1 via the first through electrode 24A, the first electrode pattern M1, and a through electrode, a wiring pattern, etc. (not shown). Furthermore, the first inductor L1 is electrically connected to an external reference potential via a through electrode, a wiring pattern, etc. (not shown).

[0063] A reference potential electrode 26, which is connected to a reference potential and has a relatively large area, is provided between the fifth package layer 12e and the sixth package layer 12f. This facilitates stabilizing the electrical connection between the acoustic wave device 1 and the reference potential. Additionally, in the first embodiment, the reference potential electrode 26 is located closer to the sixth package layer 12f than the first inductor L1 and the first electrode pattern M1. This allows the reference potential electrode 26 to function as an electromagnetic shield. This suppresses external electrical influences on the first inductor L1 and the first electrode pattern M1.

[0064] In a plan view, it is preferable that the first inductor L1 and the first electrode pattern M1 overlap with the reference potential electrode 26. In this case, external electrical influences on the first inductor L1 and the first electrode pattern M1 can be effectively suppressed. Note that the first inductor L1 and the first electrode pattern M1 do not necessarily overlap with the reference potential electrode 26 in a plan view. Alternatively, the reference potential electrode 26 may not be provided.

[0065] 1 and 5, it is preferable that no electrodes other than the electrodes connecting the first inductor L1 and the first electrode pattern M1 are located between the first inductor L1 and the first electrode pattern M1, in which case the strength of the electromagnetic coupling between the first inductor L1 and the first electrode pattern M1 can be stabilized.

[0066] It is more preferable that the first inductor L1 and the first electrode pattern M1 are provided on one main surface and the other main surface of the same package layer, thereby increasing and stabilizing the strength of the electromagnetic coupling between the first inductor L1 and the first electrode pattern M1.

[0067] However, the first inductor L1 and the first electrode pattern M1 may be provided on different package layers. In this case, the first through electrode 24A may penetrate multiple package layers. Alternatively, the first inductor L1 and the first electrode pattern M1 may be connected via multiple first through electrodes 24A each penetrating one package layer and an electrode pad connecting the multiple first through electrodes 24A to each other. Even in these cases, it is preferable that no electrodes other than the electrode connecting the first inductor L1 and the first electrode pattern M1 are located between the first inductor L1 and the first electrode pattern M1.

[0068] In the first embodiment, the first electrode pattern M1 is located closer to the acoustic wave device 1 than the first inductor L1. In other words, the distance between the first electrode pattern M1 and the principal surface closest to the acoustic wave device 1 among the plurality of principal surfaces of the plurality of package layers is shorter than the distance between the principal surface and the first inductor L1. More specifically, the distance between the first principal surface 13a of the first package layer 12a and the first electrode pattern M1 is shorter than the distance between the first principal surface 13a and the first inductor L1. However, this is not a limitation.

[0069] 7 , the first inductor L1 is located closer to the acoustic wave device 1 than the first electrode pattern M1. That is, the distance between the first main surface 13 a of the first package layer 12 a and the first inductor L1 is shorter than the distance between the first main surface 13 a and the first electrode pattern M1. In this case, the impedance of the first inductor L1 and the impedance of the first electrode pattern M1 can be easily made closer to each other.

[0070] More specifically, when the distance between the electrode pattern and the reference potential electrode 26 is short, the inductance tends to be small. On the other hand, when the width of the electrode pattern is narrow, the inductance tends to be large. In this modified example, the distance between the first electrode pattern M1 and the reference potential electrode 26 is shorter than the distance between the first inductor L1 and the reference potential electrode 26. Therefore, the inductance of the first electrode pattern M1 tends to be small. On the other hand, the width of the first electrode pattern M1 is narrower than the width of the first inductor L1. Therefore, the inductance of the first electrode pattern M1 tends to be large. As a result of these effects canceling out, the impedance of the first inductor L1 and the impedance of the first electrode pattern M1 tend to approach each other.

[0071] Additionally, in this modification, similar to the first preferred embodiment, variations in the attenuation characteristics outside the passband of an acoustic wave device serving as a filter device can be suppressed.

[0072] 1 , in the first embodiment, the IDT electrode 7 is provided on the main surface of the piezoelectric layer 4 serving as the piezoelectric film, which faces the package substrate 12. However, the IDT electrode 7 may also be provided on the main surface of the piezoelectric film, which faces the support member 3.

[0073] 8 is a schematic plan view showing the vicinity of each inductor and each electrode pattern provided on each main surface of the third package layer in the second embodiment. Fig. 9 is a schematic cross-sectional view showing the vicinity of each inductor and each electrode pattern in a cross section passing through each inductor and each electrode pattern in the second embodiment.

[0074] As shown in Fig. 8, this embodiment differs from the first embodiment in that the elastic wave device includes a second inductor L2 and a second electrode pattern M2. The second inductor L2 is formed of an electrode pattern. Except for this, the elastic wave device of this embodiment has the same configuration as elastic wave device 10 of the first embodiment. Therefore, the first inductor L1, the first electrode pattern M1, and the like are configured in the same manner as in the first embodiment.

[0075] 9, the second inductor L2 is provided on the first main surface 13d of the fourth package layer 12d. Therefore, in this embodiment, the second inductor L2 is provided on one of the main surfaces of the package layers, on which the first inductor L1 is provided. It can also be said that the second inductor L2 is provided on the second main surface 14c of the third package layer 12c.

[0076] The second electrode pattern M2 is provided on the first main surface 13c of the third package layer 12c. Thus, in this embodiment, the second electrode pattern M2 is provided on the main surface on which the first electrode pattern M1 is provided, among the main surfaces of the package layers. It can also be said that the second electrode pattern M2 is provided on the second main surface 14b of the second package layer 12b.

[0077] 8 , the second inductor L2 has a start point 39 a, an end point, multiple corners 39 c, and multiple wiring portions 39 d. Similarly, the second electrode pattern M2 has a start point 38 a, an end point, multiple corners 38 c, and multiple wiring portions 38 d. Note that the end points of the second inductor L2 and the second electrode pattern M2 are omitted in FIG. 8 .

[0078] In the second inductor L2, each wiring portion 39d connects the start point 39a to a corner portion 39c, the corner portions 39c to each other, or the corner portion 39c to an end point. In the second electrode pattern M2, each wiring portion 38d connects the start point 38a to a corner portion 38c, the corner portions 38c to each other, or the corner portion 38c to an end point.

[0079] The shape of the second electrode pattern M2 in a plan view is substantially the same as the shape of the second inductor L2 in a plan view. More specifically, in a plan view, the path from the start point 38 a to the end point of the second electrode pattern M2 overlaps with the path from the start point 39 a to the end point of the second inductor L2. The width of the second electrode pattern M2 is narrower than the width of the electrode patterns constituting the second inductor L2.

[0080] The second inductor L2 and the second electrode pattern M2 are connected by a second through electrode 34B. The second through electrode 34B penetrates the third package layer 12c. The starting points of the second inductor L2 and the second electrode pattern M2 are connected by the second through electrode 34B. The ending points of the second inductor L2 and the second electrode pattern M2 are connected by another second through electrode 34B. This allows current to flow in the same direction even if the second inductor L2 and the second electrode pattern M2 have approximately the same shape in a plan view. This allows the second inductor L2 and the second electrode pattern M2 to be electromagnetically coupled in a suitable manner.

[0081] The second inductor L2 is electrically connected to the acoustic wave element via the second through electrode 34B, the second electrode pattern M2, the through electrode 24, a wiring pattern (not shown), and the like. Furthermore, the second inductor L2 is electrically connected to an external reference potential via a through electrode, a wiring pattern (not shown), and the like. In this embodiment, the second inductor L2 is disposed closer to the acoustic wave element than the second electrode pattern M2. In other words, the distance between the second electrode pattern M2 and the acoustic wave element is longer than the distance between the second inductor L2 and the acoustic wave element. However, the distance between the second electrode pattern M2 and the acoustic wave element may be shorter than the distance between the second inductor L2 and the acoustic wave element.

[0082] The first inductor L1 and the second inductor L2 are electromagnetically coupled. The first inductor L1 and the second electrode pattern M2 are also electromagnetically coupled. Similarly, the second inductor L2 and the first electrode pattern M1 are also electromagnetically coupled. Furthermore, the first electrode pattern M1 and the second electrode pattern M2 are also electromagnetically coupled.

[0083] In this embodiment, the distance between the first inductor L1 and the first electrode pattern M1 is shorter than the distance between the first inductor L1 and the second inductor L2. This makes it possible to suitably increase the strength of the electromagnetic coupling between the first inductor L1 and the first electrode pattern M1. However, the distance between the first inductor L1 and the second inductor L2 may also be shorter than the distance between the first inductor L1 and the first electrode pattern M1.

[0084] In this embodiment, as in the first embodiment, even if a positional misalignment occurs between the first inductor L1 and the first electrode pattern M1, the area of ​​the portion where the first inductor L1 and the first electrode pattern M1 overlap in a plan view is unlikely to change, thereby suppressing variations in the strength of the electromagnetic coupling between the first inductor L1 and the first electrode pattern M1.

[0085] Furthermore, in a planar view, the second inductor L2 and the second electrode pattern M2 overlap along paths from the start point to the end point, and the width of the second electrode pattern M2 is narrower than the width of the electrode pattern of the second inductor L2. As a result, even if misalignment occurs between the second inductor L2 and the second electrode pattern M2, the area of ​​the overlapping portion between the second inductor L2 and the second electrode pattern M2 in a planar view is unlikely to change. This reduces variations in the strength of electromagnetic coupling between the second inductor L2 and the second electrode pattern M2. Therefore, variations in attenuation characteristics outside the passband of the elastic wave device as a filter device can be effectively reduced.

[0086] Note that the second electrode pattern M2 does not necessarily have to be provided. The modified example of the second embodiment shown in FIG. 10 differs from the second embodiment in that the second electrode pattern M2 is not provided. Specifically, in this modified example, a first inductor L1, a second inductor L2, and a first electrode pattern M1 are provided, as in the second embodiment. However, when viewed in a plan view, the second inductor L2 does not overlap with any of the electrode patterns provided on any of the multiple main surfaces of the multiple package layers, at least in part of the path from the start point to the end point.

[0087] For example, in this modification, an electrode pattern other than the first electrode pattern M1 may be provided on any of the multiple main surfaces of the multiple package layers, although the first electrode pattern M1 and other electrode patterns do not overlap with the second inductor L2 in plan view, at least in the cross section shown in FIG.

[0088] In this modification, as in the first embodiment, even if the first inductor L1 and the first electrode pattern M1 are misaligned, the area of ​​the overlapping portion between the first inductor L1 and the first electrode pattern M1 is unlikely to change in plan view. This reduces variations in the strength of the electromagnetic coupling between the first inductor L1 and the first electrode pattern M1. This reduces variations in the attenuation characteristics outside the passband of the elastic wave device as a filter device.

[0089] In the second embodiment, the variation in attenuation characteristics outside the passband of an acoustic wave device serving as a filter device can be further suppressed, as will be described below with reference to the second embodiment and its modifications.

[0090] A plurality of elastic wave devices having the configurations of the second embodiment and its modified examples were prepared. In the prepared elastic wave devices, the width of the electrode pattern constituting the first inductor L1 was 40 μm. The width of the first electrode pattern M1 was 34 μm. The width of the electrode pattern constituting the second inductor L2 was 40 μm. The width of the second electrode pattern M2 was 34 μm.

[0091] Here, the offset is the distance between the widthwise center of wiring portion 18d of first electrode pattern M1 and the widthwise center of wiring portion 19d of first inductor L1 in a plan view. The same applies to second electrode pattern M2 and second inductor L2. The offset in the left-right direction in FIG. 8 between the first electrode pattern M1 and the first inductor L1 differs among the prepared elastic wave devices having the configuration of the second embodiment.

[0092] Specifically, in each elastic wave device, the amount of misalignment between the first electrode pattern M1 and the first inductor L1 was set to 0 μm, 40 μm, or −40 μm. A positive misalignment is, for example, the amount of misalignment of the first electrode pattern M1 to the right in FIG. 8 relative to the first inductor L1. On the other hand, a negative misalignment is, for example, the amount of misalignment of the first electrode pattern M1 to the left in FIG. 8 relative to the first inductor L1. Note that in each elastic wave device, the amount of misalignment between the first electrode pattern M1 and the first inductor L1 is the same as the amount of misalignment between the second electrode pattern M2 and the second inductor L2.

[0093] In each of the elastic wave devices having the configuration of the modified example of the second preferred embodiment, the misalignment amount between the first electrode pattern M1 and the first inductor L1 was set to 0 μm, 40 μm, or −40 μm. The attenuation frequency characteristics of the prepared elastic wave devices were measured.

[0094] Fig. 11 is a diagram showing the attenuation frequency characteristic in the second embodiment, and Fig. 12 is a diagram showing the attenuation frequency characteristic in a modified example of the second embodiment.

[0095] As shown in Figures 11 and 12, in both the second embodiment and its modified example, the variation in attenuation characteristics outside the passband is suppressed. However, in the second embodiment, the variation in attenuation characteristics below the passband is further suppressed compared to the modified example. More specifically, as shown in Figure 11, the fluctuation in the amount of attenuation is small. The reason why the configuration of the second embodiment can further suppress the variation in attenuation characteristics will be explained below.

[0096] Fig. 13(a) is a schematic diagram showing a case where the amount of deviation is 0 μm for each inductor and each electrode pattern in the second embodiment. Fig. 13(b) is a schematic diagram showing a case where the amount of deviation is greater than 0 μm for each inductor and each electrode pattern in the second embodiment. Figs. 13(a) and 13(b) are views of each inductor and each electrode pattern from the same direction as Fig. 9, and omit the package substrate and the like.

[0097] 13A, in the second embodiment, the first inductor L1 is electromagnetically coupled not only to the first electrode pattern M1 but also to the second inductor L2 and the second electrode pattern M2. The second inductor L2 is electromagnetically coupled not only to the second electrode pattern M2 but also to the first inductor L1 and the first electrode pattern M1.

[0098] The positional relationship between the first electrode pattern M1 and the first inductor L1 shown in Fig. 13(b) is shifted from the positional relationship between the first electrode pattern M1 and the first inductor L1 shown in Fig. 13(a). Also, the positional relationship between the second electrode pattern M2 and the second inductor L2 shown in Fig. 13(b) is shifted from the positional relationship between the second electrode pattern M2 and the second inductor L2 shown in Fig. 13(a).

[0099] The positions of the first electrode pattern M1 and the second electrode pattern M2 shown in FIG. 13(b) are shifted in the same direction and by the same amount from the positions of the first electrode pattern M1 and the second electrode pattern M2 shown in FIG. 13(a). This is because multiple electrode patterns provided on the same main surface of the same package layer are provided in the same process. In this way, variation in the positional relationship between the first electrode pattern M1 and the second electrode pattern M2 is unlikely to occur. Therefore, variation in the strength of the electromagnetic coupling between the first electrode pattern M1 and the second electrode pattern M2 is unlikely to occur.

[0100] For the same reason, the positional relationship between the first inductor L1 and the second inductor L2 is unlikely to vary, and therefore the strength of the electromagnetic coupling between the first inductor L1 and the second inductor L2 is unlikely to vary.

[0101] Here, the distance between the second electrode pattern M2 and the first inductor L1 shown in Fig. 13(b) is shorter than the distance between the second electrode pattern M2 and the first inductor L1 shown in Fig. 13(a). Therefore, in the case shown in Fig. 13(b), the strength of the electromagnetic coupling between the second electrode pattern M2 and the first inductor L1 is greater than in the case shown in Fig. 13(a).

[0102] On the other hand, the distance between the second inductor L2 and the first electrode pattern M1 shown in Fig. 13(b) is longer than the distance between the second inductor L2 and the first electrode pattern M1 shown in Fig. 13(a). Therefore, the strength of the electromagnetic coupling between the second inductor L2 and the first electrode pattern M1 is smaller in the case shown in Fig. 13(b) than in the case shown in Fig. 13(a). This reduces the variation in the strength of the electromagnetic coupling across the first inductor L1, the second inductor L2, the first electrode pattern M1, and the second electrode pattern M2. Therefore, the variation in the attenuation characteristics outside the passband of the elastic wave device as a filter device can be further reduced.

[0103] The arrangement of the second electrode pattern M2 is not limited to the above. For example, the second electrode pattern M2 may be provided on one of the main surfaces of the package layers that is different from the main surface on which the first electrode pattern M1 is provided. The second electrode pattern M2 may be provided on any one of the main surfaces of the package layers.

[0104] Alternatively, for example, the second inductor L2 and the second electrode pattern M2 may be provided on different package layers. The second electrode pattern M2 may be provided on one of the main surfaces of the package layers that is different from the main surface on which the second inductor is provided. The second through electrode 34B may penetrate the multiple package layers. Alternatively, the second inductor L2 and the second electrode pattern M2 may be connected via multiple second through electrodes 34B that each penetrate one package layer and an electrode pad that connects the multiple second through electrodes 34B to each other.

[0105] However, it is preferable that no electrodes other than the electrodes connecting the second inductor L2 and the second electrode pattern M2 are located between the second inductor L2 and the second electrode pattern M2, in which case the strength of the electromagnetic coupling between the second inductor L2 and the second electrode pattern M2 can be stabilized.

[0106] As in the second embodiment, it is preferable that the first inductor L1 and the second inductor L2 are provided on the same main surface among the multiple main surfaces of the multiple package layers. In this case, it is possible to suppress variations in the strength of the electromagnetic coupling between the first inductor L1 and the second inductor L2. Note that the second inductor L2 may be provided on a main surface among the multiple main surfaces of the multiple package layers that is different from the main surface on which the first inductor L1 is provided. It is sufficient that the second inductor L2 is provided on any one of the multiple main surfaces of the multiple package layers.

[0107] In the first embodiment shown in FIG. 1 , the acoustic wave element 1 has a piezoelectric substrate 2. In the acoustic wave element 1, the acoustic reflecting portion is a cavity 1a. This is the same in the second embodiment. However, in the present invention, the acoustic reflecting portion may be an acoustic reflecting film. This example is shown in the third embodiment.

[0108] 14 is a schematic front cross-sectional view of the acoustic wave element according to the third preferred embodiment, in which sealing resin layer 17 is omitted.

[0109] This embodiment differs from the first embodiment in that the acoustic reflection portion of the acoustic wave element 41 is an acoustic reflection film 45. This embodiment also differs from the first embodiment in that the support member 43 is formed only from a support substrate. Except for the above points, the acoustic wave device of this embodiment has the same configuration as the acoustic wave device 10 of the first embodiment.

[0110] An acoustic reflection film 45 is provided on the surface of the support member 43. A piezoelectric layer 4 serving as a piezoelectric film is provided on the acoustic reflection film 45. In this embodiment, the entire support member 43 and the entire piezoelectric film face each other with the acoustic reflection film 45 sandwiched between them. However, for example, the acoustic reflection film 45 may be provided in the recess of the insulating layer 5 shown in FIG. 1 . It is sufficient that the support member 43 and the piezoelectric film are arranged so that at least a portion of the support member 43 and at least a portion of the piezoelectric film face each other with the acoustic reflection film 45 sandwiched between them. It is also sufficient that the IDT electrode 7 and the acoustic reflection film 45 overlap in a planar view.

[0111] The acoustic reflection film 45 is a laminate of multiple acoustic impedance layers. Specifically, the acoustic reflection film 45 has multiple low acoustic impedance layers and multiple high acoustic impedance layers. The low acoustic impedance layers are layers with relatively low acoustic impedance. More specifically, the multiple low acoustic impedance layers of the acoustic reflection film 45 are low acoustic impedance layers 46 a and 46 b.

[0112] On the other hand, the high acoustic impedance layer is a layer with a relatively high acoustic impedance. More specifically, the multiple high acoustic impedance layers of the acoustic reflecting film 45 are high acoustic impedance layers 47a and high acoustic impedance layers 47b. The low acoustic impedance layers and high acoustic impedance layers are alternately stacked. The low acoustic impedance layer 46a is the layer of the acoustic reflecting film 45 that is located closest to the piezoelectric layer 4.

[0113] The acoustic reflection film 45 has two low acoustic impedance layers and two high acoustic impedance layers, although it is sufficient that the acoustic reflection film 45 has at least one low acoustic impedance layer and one high acoustic impedance layer.

[0114] The low acoustic impedance layer may be made of, for example, silicon oxide or aluminum, while the high acoustic impedance layer may be made of, for example, metals such as platinum or tungsten, or dielectrics such as aluminum nitride, silicon nitride, or hafnium oxide.

[0115] This embodiment is configured similarly to the first embodiment except for the acoustic wave element 41. Therefore, as shown in FIG. 1 , in a plan view, the first inductor L1 and the first electrode pattern M1 overlap along paths from the start point to the end point, and the width of the first electrode pattern M1 is narrower than the width of the electrode pattern of the first inductor L1. This reduces variations in the strength of electromagnetic coupling between the first inductor L1 and the first electrode pattern M1. This reduces variations in the attenuation characteristics outside the passband of the acoustic wave device as a filter device.

[0116] In the first to third embodiments, examples have been shown in which the elastic wave resonator is configured to use a thickness-shear bulk wave as the main mode. However, in the present invention, the elastic wave resonator may be configured to use, for example, a plate wave as the main mode. This example is shown in the fourth embodiment.

[0117] 15 is a schematic bottom view illustrating the electrode configuration of an acoustic wave resonator according to the fourth preferred embodiment, in which wiring and the like connected to the acoustic wave resonator are omitted.

[0118] This embodiment differs from the first embodiment in that the elastic wave resonator 51 includes a pair of reflectors 58 and 59. This embodiment also differs from the first embodiment in that the elastic wave resonator 51 is configured to utilize plate waves, such as Lamb waves, as its primary mode. Except for the above points, the elastic wave device of this embodiment has a similar configuration to the elastic wave device 10 of the first embodiment.

[0119] The reflectors 58 and 59 are provided on the piezoelectric layer 4 as a piezoelectric film. Specifically, the reflectors 58 and 59 face each other in the direction perpendicular to the electrode fingers, with the IDT electrode 7 interposed therebetween.

[0120] The reflector 58 has a pair of reflector bus bars and a plurality of reflector electrode fingers 56. Specifically, the pair of reflector bus bars is a first reflector bus bar 55 a and a second reflector bus bar 55 b. The first reflector bus bar 55 a and the second reflector bus bar 55 b face each other. One end of each of the plurality of reflector electrode fingers 56 is connected to the first reflector bus bar 55 a. The other end of each of the plurality of reflector electrode fingers 56 is connected to the second reflector bus bar 55 b. The reflector 59 has a similar configuration to the reflector 58.

[0121] When the elastic wave resonator 51 is configured to be able to use a plate wave as the main mode, it is preferable to have a pair of reflectors, which can improve the resonance characteristics of the elastic wave resonator 51.

[0122] Additionally, in this embodiment, as in the first embodiment, variations in attenuation characteristics outside the passband can be suppressed in an acoustic wave device serving as a filter device.

[0123] In the first to fourth embodiments, examples have been shown in which the elastic wave device is a filter device. However, as described above, an elastic wave device of the present invention may include at least one elastic wave resonator. The elastic wave device of the present invention may also be used in a filter device together with other resonators. In this case, variations in attenuation characteristics outside the passband can be suppressed in a filter device using the elastic wave device of the present invention.

[0124] A preferred configuration of the present invention will be described below.

[0125] In the first to third embodiments, where d is the thickness of the piezoelectric film and p is the center-to-center distance between adjacent electrode fingers, d / p is 0.5 or less. It is preferable that d / p is 0.24 or less. This allows thickness-shear mode bulk waves to be more effectively excited and enables the value of the bandwidth fraction of the elastic wave resonator to be sufficiently large. The bandwidth fraction is expressed as (|fa-fr| / fr) x 100 [%], where fr is the resonant frequency and fa is the antiresonant frequency.

[0126] FIG. 16 is a graph showing the relationship between d / p and the bandwidth fraction of an elastic wave resonator.

[0127] As is clear from FIG. 16, when d / p>0.5, the fractional bandwidth is less than 5%. In contrast, when d / p≦0.5, the fractional bandwidth can be increased to 5% or more. This increases the electromechanical coupling coefficient of the thickness-shear mode bulk wave. When d / p≦0.24, the fractional bandwidth can be increased to 7% or more. This effectively increases the electromechanical coupling coefficient of the thickness-shear mode bulk wave.

[0128] When the metallization ratio of the electrode fingers to the excitation region C is MR, it is preferable to satisfy MR≦1.75(d / p)+0.075. In this case, the value of the fractional bandwidth of the acoustic wave resonator does not become too large, and spurious emissions between the resonant frequency and the antiresonant frequency can be suppressed. Details of this are described below.

[0129] In this specification, the metallization ratio MR of the electrode fingers to the excitation region C is the ratio of the portion of the piezoelectric layer 4 covered with the metal constituting the electrode fingers to the excitation region C in a plan view. Specifically, the metallization ratio MR is the ratio of the area of ​​the first electrode finger 16 a and the second electrode finger 16 b in the excitation region C to the area of ​​the excitation region C in a plan view. However, if the width of the electrode fingers located in the excitation region C is constant, the metallization ratio MR can also be calculated by dividing the sum of the widths of the electrode fingers located in the excitation region C by the dimension of the excitation region C in the direction perpendicular to the electrode fingers. The width of the electrode fingers is the dimension of the electrode fingers in the direction perpendicular to the electrode fingers.

[0130] Fig. 17 is a diagram showing the relationship between the bandwidth ratio and the normalized magnitude of spurious in an elastic wave resonator. Fig. 17 shows the results of measuring the amount of phase rotation of spurious every time the bandwidth ratio is changed by changing the thickness of the piezoelectric layer and the dimensions of the electrode fingers. The normalized magnitude of spurious in Fig. 17 is specifically a value obtained by normalizing the amount of phase rotation of the spurious impedance by 180°. The results shown in Fig. 17 are for a Z-cut LiNbO ３ Although this is the result when a piezoelectric layer made of this material was used, the same tendency is observed when a piezoelectric layer having another cut angle is used.

[0131] In the region surrounded by ellipse E in Fig. 17, the normalized magnitude of the spurious response between the resonant frequency and the anti-resonant frequency is 1.0. If the bandwidth fraction of the elastic wave resonator exceeds 17%, the normalized magnitude of the spurious response may be 1.0 or more. For this reason, it is preferable that the bandwidth fraction be 17% or less. This makes it possible to suppress the spurious response between the resonant frequency and the anti-resonant frequency.

[0132] 18 is a diagram showing the relationship between d / p, metallization ratio MR, and bandwidth fraction, in which the bandwidth fraction is calculated for each of different d / p and metallization ratio MR.

[0133] In Figure 18, the hatched area is the area where the fractional bandwidth is 17% or less. The boundary between this hatched area and the non-hatched area is roughly represented by dashed line G. Dashed line G is represented by MR = 1.75(d / p) + 0.075. It is preferable that MR ≤ 1.75(d / p) + 0.075. In this case, it is easy to keep the fractional bandwidth at 17% or less.

[0134] On the other hand, the dashed-dotted line G1 in Figure 18 indicates the boundary where the slope of the change in metallization ratio MR with respect to the change in d / p is the same as that of the dashed line G, and where the fractional bandwidth is 17% or less over the entire range. The dashed-dotted line G1 is represented by MR = 1.75(d / p) + 0.05. It is more preferable that MR ≤ 1.75(d / p) + 0.05. In this case, the fractional bandwidth can be more reliably kept at 17% or less.

[0135] FIG. 19 shows the results of LiNbO when d / p approaches 0. ３ 19 is a diagram showing a map of fractional bandwidths with respect to Euler angles (0°, θ, ψ) of the piezoelectric layer. The hatched area in FIG. 19 is a region where a fractional bandwidth of at least 5% or more can be obtained, and the range of this region can be approximated to the ranges expressed by the following formulas (1), (2), and (3). The same applies when the piezoelectric layer is made of lithium tantalate.

[0136] (0°±10°, 0° to 20°, any ψ) ... Equation (1) (0°±10°, 20° to 80°, 0° to 60° (1-(θ-50) ２ / 900) １／２ ) or (0°±10°, 20° to 80°, [180°-60° (1-(θ-50) ２ / 900) １／２ ]~180°) ...Formula (2) (0°±10°, [180°-30°(1-(ψ-90) ２ / 8100) １／２ ] to 180°, any ψ) ...Equation (3)

[0137] It is preferable that the piezoelectric layer is made of lithium niobate or lithium tantalate, and that the Euler angles (φ, θ, ψ) of the lithium niobate or lithium tantalate constituting the piezoelectric layer are within the range of the above formula (1), formula (2), or formula (3), thereby making it possible to sufficiently widen the fractional bandwidth of the elastic wave resonator.

[0138] In the following, examples of the configuration of the acoustic wave device according to the present invention will be described together.

[0139] <1> An elastic wave device comprising: an elastic wave element; a package substrate on which the elastic wave element is mounted, the package substrate being formed by stacking a plurality of package layers, each having two main surfaces facing each other; a first inductor provided on one of the main surfaces of one of the package layers; a first electrode pattern provided on one of the main surfaces of the plurality of package layers other than the main surface on which the first inductor is provided; and a first through electrode connecting the first inductor and the first electrode pattern and penetrating at least one of the package layers, wherein, when viewed in a plane, the first inductor and the first electrode pattern overlap on paths from a start point to an end point, and the width of the first electrode pattern is narrower than the width of the electrode pattern constituting the first inductor.

[0140] <2> The elastic wave device described in <1>, in which no electrodes other than the electrodes connecting the first inductor and the first electrode pattern are positioned between the first inductor and the first electrode pattern.

[0141] <3> The acoustic wave device according to <2>, wherein the first inductor and the first electrode pattern are provided on one of the principal surfaces and the other of the principal surfaces of the same package layer.

[0142] <4> An elastic wave device described in any one of <1> to <3>, wherein the distance between the main surface of the plurality of package layers that is closest to the elastic wave element and the first inductor is shorter than the distance between the main surface and the first electrode pattern.

[0143] <5> The elastic wave device according to any one of <1> to <4>, further comprising: a second inductor provided on one of the plurality of main surfaces of the plurality of package layers; a second electrode pattern provided on one of the plurality of main surfaces of the plurality of package layers other than the main surface on which the second inductor is provided; and a second through electrode connecting the second inductor and the second electrode pattern and penetrating at least one of the package layers, wherein, when viewed in a plane, the second inductor and the second electrode pattern overlap on paths from a start point to an end point, and the width of the second electrode pattern is narrower than the width of the electrode pattern constituting the second inductor.

[0144] <6> The acoustic wave device according to <5>, wherein the distance between the first inductor and the first electrode pattern is shorter than the distance between the first inductor and the second inductor.

[0145] <7> The acoustic wave device according to <5> or <6>, wherein the distance between the second electrode pattern and the acoustic wave element is longer than the distance between the second inductor and the acoustic wave element.

[0146] <8> An elastic wave device according to any one of <1> to <4>, further comprising a second inductor provided on the main surface of the package layer on which the first inductor is provided, among the plurality of main surfaces of the plurality of package layers, wherein, when viewed in a plan view, the second inductor does not overlap with any electrode pattern provided on any of the plurality of main surfaces of the plurality of package layers, in at least a portion of the path from the start point to the end point.

[0147] <9> The elastic wave device according to any one of <1> to <8>, wherein the elastic wave element includes a support member, a piezoelectric film provided on the support member and including a piezoelectric layer made of a piezoelectric material, and an IDT electrode provided on the piezoelectric film and including a plurality of electrode fingers, wherein an acoustic reflection portion is formed on the support member at a position overlapping the IDT electrode in a planar view, and wherein d / p is 0.5 or less, where d is the thickness of the piezoelectric film and p is the center-to-center distance between adjacent electrode fingers.

[0148] <10> An elastic wave device described in <9>, wherein the acoustic reflection portion is a hollow portion, and the support member and the piezoelectric film are arranged so that a portion of the support member and a portion of the piezoelectric film face each other across the hollow portion.

[0149] <11> The elastic wave device described in <9>, wherein the acoustic reflection portion is an acoustic reflection film including a high acoustic impedance layer having a relatively high acoustic impedance and a low acoustic impedance layer having a relatively low acoustic impedance, and the support member and the piezoelectric film are arranged so that at least a portion of the support member and at least a portion of the piezoelectric film face each other across the acoustic reflection film.

[0150] <12> The acoustic wave device according to any one of <9> to <11>, wherein d / p is 0.24 or less.

[0151] <13> An elastic wave device according to any one of <9> to <12>, wherein, when a direction perpendicular to the direction in which the plurality of electrode fingers extend is defined as an electrode finger perpendicular direction, adjacent electrode fingers overlap in the electrode finger perpendicular direction, and the region between the centers of adjacent electrode fingers is an excitation region, and when the metallization ratio of the electrode fingers to the excitation region is defined as MR, MR≦1.75(d / p)+0.075 is satisfied.

[0152] <14> The acoustic wave device according to any one of <9> to <13>, wherein the piezoelectric layer is made of lithium niobate or lithium tantalate, and the Euler angles (φ, θ, ψ) of the lithium niobate or lithium tantalate constituting the piezoelectric layer are within the range of the following formula (1), formula (2), or formula (3): (0°±10°, 0° to 20°, any ψ) ... formula (1) (0°±10°, 20° to 80°, 0° to 60° (1-(θ-50) ２ / 900) １／２ ) or (0°±10°, 20° to 80°, [180°-60° (1-(θ-50) ２ / 900) １／２ ]~180°) ...Formula (2) (0°±10°, [180°-30°(1-(ψ-90) ２ / 8100)１／２ ] to 180°, any ψ) ...Equation (3)

[0153] REFERENCE SIGNS LIST 1...acoustic wave element 1a...cavity 2...piezoelectric substrate 3...support member 4...piezoelectric layer 5...insulating layer 6...support substrate 7...IDT electrode 8...electrode pad 9...bump 10...acoustic wave device 11...acoustic wave resonator 12...package substrate 12a to 12f...first to sixth package layers 13a, 13c, 13d...first main surface 14b, 14c, 14f...second main surface 15a, 15b...first and second bus bars 16a, 16b...first and second electrode fingers 17...sealing resin layer 18a...starting point 18b...ending point 18c...corner portion 18d...wiring portion 19a...starting point 19b...ending point 19c...corner portion 19d...wiring portion 19e...wiring portion 23...mounting electrode land 24...Through electrode 24A...First through electrode 25...Wiring pattern 26...Reference potential electrode 27...External connection electrode land 34B...Second through electrode 38a...Starting point 38c...Corner portion 38d...Wiring portion 39a...Starting point 39c...Corner portion 39d...Wiring portion 41...Acoustic wave element 43...Support member 45...Acoustic reflection film 46a, 46b...Low acoustic impedance layer 47a, 47b...High acoustic impedance layer 51...Acoustic wave resonator 55a, 55b...First and second reflector bus bars 56...Reflector electrode fingers 58, 59...Reflectors A...Crossing region C...Excitation region L1, L2...First and second inductors La to Lc...Inductors M1, M2...First and second electrode patterns

Claims

1. An elastic wave device comprising: an elastic wave element; a package substrate on which the elastic wave element is mounted, the package substrate being formed by stacking a plurality of package layers, each having two main surfaces facing each other; a first inductor provided on one of the main surfaces of one of the package layers; a first electrode pattern provided on one of the main surfaces of the plurality of package layers other than the main surface on which the first inductor is provided; and a first through electrode connecting the first inductor and the first electrode pattern and penetrating at least one of the package layers, wherein, when viewed in a plane, the first inductor and the first electrode pattern overlap on paths from a start point to an end point, and the width of the first electrode pattern is narrower than the width of the electrode pattern constituting the first inductor.

2. The elastic wave device according to claim 1, wherein no electrodes other than the electrode connecting the first inductor and the first electrode pattern are located between the first inductor and the first electrode pattern.

3. The acoustic wave device according to claim 2, wherein the first inductor and the first electrode pattern are provided on one of the principal surfaces and the other of the principal surfaces of the same package layer.

4. An elastic wave device according to any one of claims 1 to 3, wherein the distance between the main surface of the plurality of package layers that is closest to the elastic wave element and the first inductor is shorter than the distance between the main surface and the first electrode pattern.

5. The elastic wave device according to any one of claims 1 to 4, further comprising: a second inductor provided on one of the plurality of main surfaces of the plurality of package layers; a second electrode pattern provided on one of the plurality of main surfaces of the plurality of package layers other than the main surface on which the second inductor is provided; and a second through electrode connecting the second inductor and the second electrode pattern and penetrating at least one of the package layers, wherein, in a planar view, the second inductor and the second electrode pattern overlap on paths from a start point to an end point, and the width of the second electrode pattern is narrower than the width of the electrode pattern constituting the second inductor.

6. The acoustic wave device according to claim 5, wherein the distance between the first inductor and the first electrode pattern is shorter than the distance between the first inductor and the second inductor.

7. The acoustic wave device according to claim 5 or 6, wherein the distance between the second electrode pattern and the acoustic wave element is longer than the distance between the second inductor and the acoustic wave element.

8. The elastic wave device according to any one of claims 1 to 4, further comprising a second inductor provided on the main surface of the package layer on which the first inductor is provided, among the plurality of main surfaces of the plurality of package layers, wherein, in a plan view, the second inductor does not overlap with any electrode pattern provided on any of the plurality of main surfaces of the plurality of package layers, in at least a portion of the path from the start point to the end point.

9. The elastic wave device according to any one of claims 1 to 8, wherein the elastic wave element comprises a support member, a piezoelectric film provided on the support member and including a piezoelectric layer made of a piezoelectric material, and an IDT electrode provided on the piezoelectric film and including a plurality of electrode fingers, wherein an acoustic reflecting portion is formed on the support member at a position overlapping the IDT electrode in a planar view, and wherein d is the thickness of the piezoelectric film and p is the center-to-center distance between adjacent electrode fingers, and d / p is 0.5 or less.

10. The elastic wave device according to claim 9, wherein the acoustic reflection portion is a hollow portion, and the support member and the piezoelectric film are arranged so that a portion of the support member and a portion of the piezoelectric film face each other across the hollow portion.

11. The elastic wave device according to claim 9, wherein the acoustic reflection portion is an acoustic reflection film including a high acoustic impedance layer having a relatively high acoustic impedance and a low acoustic impedance layer having a relatively low acoustic impedance, and the support member and the piezoelectric film are arranged so that at least a portion of the support member and at least a portion of the piezoelectric film face each other with the acoustic reflection film in between.

12. The elastic wave device according to any one of claims 9 to 11, wherein d / p is 0.24 or less.

13. The elastic wave device according to any one of claims 9 to 12, wherein, when a direction perpendicular to the direction in which the plurality of electrode fingers extend is defined as an electrode finger perpendicular direction, a region in which adjacent electrode fingers overlap in the electrode finger perpendicular direction and a region between the centers of adjacent electrode fingers is an excitation region, and when a metallization ratio of the electrode fingers to the excitation region is defined as MR, MR≦1.75(d / p)+0.075 is satisfied.

14. The acoustic wave device according to any one of claims 9 to 13, wherein the piezoelectric layer is made of lithium niobate or lithium tantalate, and the Euler angles (φ, θ, ψ) of the lithium niobate or lithium tantalate constituting the piezoelectric layer are within the range of the following formula (1), formula (2), or formula (3): (0°±10°, 0° to 20°, any ψ) ... formula (1) (0°±10°, 20° to 80°, 0° to 60° (1-(θ-50) ２ / 900) １／２ ) or (0°±10°, 20° to 80°, [180°-60° (1-(θ-50) ２ / 900) １／２ ]~180°) ...Formula (2) (0°±10°, [180°-30°(1-(ψ-90) ２ / 8100) １／２ ] to 180°, any ψ) ...Equation (3)

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