Acoustic wave filter device

Abstract

This acoustic wave filter device includes: a series arm resonator that is connected between an input terminal and an output terminal; a parallel arm resonator that is connected between a node, which is on a path connecting the input terminal and the output terminal, and a ground terminal; and a capacitive element that is connected between the input terminal and the output terminal, and that is connected in parallel with the series arm resonator. The acoustic wave filter device includes a plurality of series arm resonators. The capacitive element is connected in parallel to, among the plurality of series arm resonators, a series arm resonator that is connected to the input terminal.

Description

Elastic wave filter device

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

[0002] Patent Documents 1 to 3 describe acoustic wave devices (referred to as acoustic wave devices in Patent Document 2 and as electrical components in Patent Document 3) that include a SAW (Surface Acoustic Wave) element that utilizes surface waves or a BAW (Bulk Acoustic Wave) element that utilizes bulk waves. For example, the acoustic wave device in Patent Document 1 discloses a configuration in which an LC circuit is provided in a cover member.

[0003] International Publication No. 2017 / 110308 Japanese Patent Application Laid-Open No. 2016-152612 Japanese Patent Application Laid-Open No. 2010-526456

[0004] Such acoustic wave devices are required to be miniaturized and have good adjustable passband characteristics.

[0005] An object of the present invention is to provide an acoustic wave filter device that can be miniaturized and has favorable adjustable pass characteristics.

[0006] An acoustic wave filter device according to one aspect includes a series arm resonator connected between an input terminal and an output terminal, a parallel arm resonator connected between a node on a path connecting the input terminal and the output terminal and a ground terminal, and a capacitive element connected between the input terminal and the output terminal and in parallel with the series arm resonator.

[0007] According to an acoustic wave filter device of the present invention, it is possible to achieve miniaturization and to adjust the pass characteristics favorably.

[0008] FIG. 1 is a circuit diagram illustrating an acoustic wave filter device according to a first preferred embodiment of the present invention. FIG. 2 is a plan view illustrating the acoustic wave filter device according to the first preferred embodiment of the present invention. FIG. 3 is a plan view illustrating a portion of the acoustic wave filter device according to the first preferred embodiment of the present invention. FIG. 4 is a cross-sectional view taken along line IV-IV′ in FIG. 3 . FIG. 5 is a graph schematically illustrating the pass characteristics of acoustic wave filter devices according to examples and comparative examples. FIG. 6 is a graph schematically illustrating the impedance characteristics of series arm resonators and parallel arm resonators according to examples and comparative examples. FIG. 7 is a plan view illustrating an acoustic wave filter device according to a second preferred embodiment of the present invention. FIG. 8 is a cross-sectional view illustrating the acoustic wave filter device according to the second preferred embodiment of the present invention. FIG. 9 is a plan view illustrating a portion of an acoustic wave filter device according to a third preferred embodiment of the present invention. FIG. 10 is a cross-sectional view taken along line XX′ in FIG. 9 . FIG. 11 is a plan view illustrating a portion of an acoustic wave filter device according to a modification of the third preferred embodiment of the present invention. FIG. 12 is a cross-sectional view illustrating an acoustic wave filter device according to a fourth preferred embodiment of the present invention.

[0009] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to these embodiments. Note that each embodiment described in the present disclosure is illustrative, and partial substitution or combination of configurations between different embodiments is possible. In modified examples and the second and subsequent embodiments, descriptions of matters common to the first embodiment will be omitted, and only differences will be described. In particular, similar effects resulting from similar configurations will not be mentioned in each embodiment.

[0010] 1 is a circuit diagram illustrating an acoustic wave filter device according to a first preferred embodiment of the present invention. The resonators included in the acoustic wave filter device 10 according to the first preferred embodiment are bulk acoustic wave (BAW) elements.

[0011] 1 , the acoustic wave filter device 10 according to the first preferred embodiment includes a plurality of series arm resonators S1, S2, S3, S4, S5, and S6, a plurality of parallel arm resonators P1, P2, P3, P4, and P5, and a capacitive element 40. The series arm resonators S1, S2, S3, S4, S5, and S6 are connected in series to a signal path between an input terminal 61 and an output terminal 62. The parallel arm resonators P1, P2, P3, P4, and P5 are connected in parallel between a node on the signal path connecting the input terminal 61 and the output terminal 62 and a ground terminal 63. The acoustic wave filter device 10 according to the first preferred embodiment is a so-called ladder filter.

[0012] One terminal of each of the series-connected series arm resonators S1, S2, S3, S4, S5, and S6 is electrically connected to an input terminal 61, and the other terminal is electrically connected to an output terminal 62. One terminal of the parallel arm resonator P1 is electrically connected to a node on a signal path connecting the series arm resonators S1 and S2, and the other terminal is electrically connected to a ground terminal 63. One terminal of the parallel arm resonator P2 is electrically connected to a node on a signal path connecting the series arm resonators S2 and S3, and the other terminal is electrically connected to the ground terminal 63.

[0013] One terminal of the parallel arm resonator P3 is electrically connected to a node on the signal path connecting the series arm resonators S3 and S4, and the other terminal is electrically connected to the ground terminal 63. One terminal of the parallel arm resonator P4 is electrically connected to a node on the signal path connecting the series arm resonators S4 and S5, and the other terminal is electrically connected to the ground terminal 63. One terminal of the parallel arm resonator P5 is electrically connected to a node on the signal path connecting the series arm resonators S5 and S6, and the other terminal is electrically connected to the ground terminal 63.

[0014] The capacitive element 40 is connected in parallel to the series arm resonator S1. That is, the capacitive element 40 is connected between the input terminal 61 and the output terminal 62, and is also connected in parallel to the series arm resonator S1. More specifically, one end of the capacitive element 40 is electrically connected to a node on the signal path connecting the input terminal 61 and the series arm resonator S1. The other end of the capacitive element 40 is electrically connected to a node on the signal path connecting the series arm resonators S2 and S3.

[0015] Next, a configuration example of an acoustic wave filter device 10 according to a first preferred embodiment of the present invention will be described with reference to FIGS. 2 to 4. FIG. 2 is a plan view illustrating the acoustic wave filter device according to the first preferred embodiment of the present invention. FIG. 3 is a plan view illustrating a portion of the acoustic wave filter device according to the first preferred embodiment of the present invention. FIG. 4 is a cross-sectional view taken along line IV-IV′ in FIG. 3. Note that FIG. 3 is a plan view illustrating the acoustic wave filter device 10 according to the first preferred embodiment of the present invention, excluding a lid 70. In addition, in FIG. 3, the plurality of series arm resonators S1, S2, S3, S4, S5, and S6 and the plurality of parallel arm resonators P1, P2, P3, P4, and P5 are indicated by hatching for ease of viewing.

[0016] 2 to 4 , the acoustic wave filter device 10 includes a support member 13, a piezoelectric layer 20, an upper electrode 31, and a lower electrode 32. The acoustic wave filter device 10 also includes a lid 70 provided above the resonator, a capacitive element 40, inter-element connection electrodes 58 and 59, terminals 60, bumps 53, vias 71, a connection member 72, and sealing portions 74 and 75.

[0017] In the following description, the thickness direction of the piezoelectric layer 20 is referred to as the Z direction, the direction perpendicular to the Z direction is referred to as the X direction, and the direction perpendicular to the Z direction and the X direction is referred to as the Y direction. The X direction and the Y direction are each parallel to the surface (first main surface 20a) of the piezoelectric layer 20. In the following description, a plan view refers to the positional relationship when viewed from a direction perpendicular to the first main surface 20a of the piezoelectric layer 20 (Z direction).

[0018] 2 , the elastic wave filter device 10 includes a plurality of terminals 60 (an input terminal 61, an output terminal 62, and a plurality of ground terminals 63) that are provided on the upper surface of the lid 70. The input terminal 61 of the plurality of terminals 60 is located at the bottom left of the lid 70. The output terminal 62 of the plurality of terminals 60 is located at the top right of the lid 70. The remaining terminals 60 other than the input terminal 61 and the output terminal 62 are ground terminals 63. The capacitive element 40 is provided on the surface (bottom surface) of the lid 70 that faces the support member 13, at a position that overlaps with the series arm resonator S1 (see FIG. 3 ).

[0019] 3 , the elastic wave filter device 10 includes a plurality of series arm resonators S1, S2, S3, S4, S5, and S6 and a plurality of parallel arm resonators P1, P2, P3, P4, and P5, which are provided on a support member 13. In the following description, unless it is necessary to distinguish between the plurality of series arm resonators S1, S2, S3, S4, S5, and S6 and the plurality of parallel arm resonators P1, P2, P3, P4, and P5, they will be simply referred to as resonators.

[0020] Each resonator is electrically connected to each terminal 60 on the lid portion 70 via a node on a signal path formed in the support member 13, a connection member 72, and a via 71 (see FIG. 4).

[0021] 2 and 3 , a sealing portion 74 is provided on the outer edge of the lid portion 70. Furthermore, a sealing portion 75 is provided on the outer edge of the support member 13. The sealing portions 74, 75 are provided in a frame shape in plan view, surrounding the multiple resonators and multiple terminals 60. The lid portion 70 and the support member 13 are arranged opposite each other, and the sealing portions 74, 75 are overlapped and joined together, thereby sealing the space surrounded by the lid portion 70, the support member 13, and the sealing portions 74, 75.

[0022] 2 and 3 are merely examples of the arrangement of the resonators, the terminals 60, and the wiring connecting them, and may be modified as appropriate. For example, the terminals 60 are arranged along the outer edge of the lid 70, but are not limited to this and may be provided in the center of the lid 70.

[0023] Next, the layered structure of the acoustic wave filter device 10 will be described with reference to Fig. 4. Among the multiple resonators, Fig. 4 describes the layered structure of the series arm resonator S1. However, except for the configurations of the capacitive element 40 and the inter-element connecting electrodes 58 and 59 in Fig. 4, the description of the series arm resonator S1 can also be applied to the other resonators.

[0024] As shown in FIG. 4, a lower electrode 32, a piezoelectric layer 20, and an upper electrode 31 are laminated in this order on a support member 13 to form a series arm resonator S1.

[0025] The support member 13 is provided opposite the second main surface 20b of the piezoelectric layer 20. The support member 13 includes a support substrate 11 and an insulating layer 12. The support substrate 11 is made of silicon (Si), quartz crystal, or the like. The insulating layer 12 is provided between the support substrate 11 and the piezoelectric layer 20. The insulating layer 12 is made of an insulating material such as silicon oxide. Note that the support member 13 may be configured without the insulating layer 12, with the piezoelectric layer 20 being provided on the support substrate 11.

[0026] A cavity 14 (hollow portion) is formed on the surface of the support member 13 (insulating layer 12) facing the second main surface 20b of the piezoelectric layer 20. The cavity 14 is provided so as to overlap, in plan view, with the excitation region 21 of the resonator, which is configured by overlapping the piezoelectric layer 20, the upper electrode 31, and the lower electrode 32. This allows bulk waves to be reflected by the cavity 14.

[0027] The piezoelectric layer 20 is in the form of a flat plate having a first main surface 20a and a second main surface 20b opposite to the first main surface 20a. The piezoelectric layer 20 is made of lithium niobate (LiNbO ３ ) or lithium tantalate (LiTaO ３ The thickness of the piezoelectric layer 20 is not particularly limited, but is preferably 1 μm or less.

[0028] The upper electrode 31 is provided on the first main surface 20a of the piezoelectric layer 20. The upper electrode 31 has a portion that overlaps with the cavity portion 14 of the insulating layer 12 and a portion that extends outward beyond the cavity portion 14.

[0029] The lower electrode 32 is provided on the second main surface 20b of the piezoelectric layer 20, in a region where at least a portion of the lower electrode 32 overlaps with the upper electrode 31. The lower electrode 32 has a portion that overlaps with the cavity portion 14 and the upper electrode 31, and a portion that does not overlap with the cavity portion 14 or the upper electrode 31 and extends outside the cavity portion 14. In addition, an adhesion layer made of Ti, NiCr, or the like may be provided between the lower electrode 32 and the insulating layer 12.

[0030] The acoustic wave filter device 10 has a so-called membrane structure in which a cavity 14 (hollow portion) is provided on the second principal surface 20b side of the piezoelectric layer 20. In the region overlapping with the cavity 14, the piezoelectric layer 20 is disposed between the upper electrode 31 and the lower electrode 32 in the Z direction. This allows bulk waves to propagate between the upper electrode 31 and the lower electrode 32. In the following description, the region where the upper electrode 31 and the lower electrode 32 overlap in a plan view may be referred to as the excitation region 21 of the resonator.

[0031] 4, for example, a portion (wiring portion) of the upper electrode 31 extending outside the cavity portion 14 is electrically connected to the input terminal 61, and a portion (wiring portion) of the lower electrode 32 extending outside the cavity portion 14 is electrically connected to the series arm resonator S2 and the parallel arm resonator P1. However, without being limited to this, a configuration may also be adopted in which the upper electrode 31 is electrically connected to the series arm resonator S2 and the parallel arm resonator P1, and the lower electrode 32 is electrically connected to the input terminal 61.

[0032] The upper electrode 31 and the lower electrode 32 are formed of a metal such as aluminum (Al), platinum (Pt), copper (Cu), tungsten (W), or molybdenum (Mo), or an alloy containing at least one of these materials. The upper electrode 31 and the lower electrode 32 may be a laminated film.

[0033] The lid portion 70 is disposed opposite the first main surface 20a of the piezoelectric layer 20. The connecting member 72 is provided between the lid portion 70 and the first main surface 20a of the piezoelectric layer 20. The lid portion 70 is formed of the same material as the support substrate 11, for example, silicon (Si), quartz crystal, or the like. Furthermore, a plurality of terminals 60 and bumps 53 are provided on the upper surface of the lid portion 70 (the side opposite the surface facing the first main surface 20a of the piezoelectric layer 20).

[0034] One of the upper electrode 31 and the lower electrode 32 constituting the series arm resonator S1 is electrically connected to an input terminal 61 provided on the upper surface of the lid portion 70 via a connecting member 72 and a via 71 that penetrates the lid portion 70.

[0035] The capacitive element 40 is provided on the surface of the lid portion 70 facing the first main surface 20a of the piezoelectric layer 20. The capacitive element 40 is disposed in a region overlapping with the excitation region 21 of the series arm resonator S1.

[0036] As shown in FIG. 2 , the capacitance element 40 is formed in a planar shape and includes an IDT (Interdigital Transducer) electrode. The capacitance element 40 includes electrode fingers 41 and 42 and busbar electrodes 43 and 44. The electrode fingers 41 extend in the Y direction, and one end of the electrode fingers 41 is connected to the busbar electrode 43. The electrode fingers 42 extend in the Y direction, and the other end of the electrode fingers 42 is connected to the busbar electrode 44. The electrode fingers 41 and the electrode fingers 42 are alternately arranged in the X direction with a gap therebetween. The busbar electrodes 43 and 44 each extend in the X direction and are spaced apart in the Y direction. The electrode fingers 41 and 42 are arranged between the busbar electrodes 43 and 44. The capacitance of the capacitance element 40 is formed between the electrode fingers 41 and the electrode fingers 42 that are spaced apart from each other.

[0037] A connection wiring 45 is connected to the bus bar electrode 43 of the capacitance element 40. A connection wiring 46 is connected to the bus bar electrode 44 of the capacitance element 40.

[0038] 4 , the inter-element connection electrodes 58, 59 are provided between the support member 13 and the lid portion 70. The inter-element connection electrode 58 (first inter-element connection electrode) electrically connects the connection wiring 45 connected to one end of the capacitance element 40 to the upper electrode 31. The inter-element connection electrode 59 (second inter-element connection electrode) electrically connects the connection wiring 46 connected to the other end of the capacitance element 40 to the lower electrode 32. More specifically, the inter-element connection electrode 59 is connected to the lower electrode 32 through an opening provided in the piezoelectric layer 20.

[0039] With this configuration, the capacitive element 40 is connected in parallel to the series arm resonator S1 via the connection wirings 45 and 46 and the inter-element connection electrodes 58 and 59. The connection wirings 45 and 46 are the same as the wiring portion described above, and the material used for the wiring portion can also be applied to the connection wirings 45 and 46.

[0040] Fig. 5 is a graph schematically illustrating the pass characteristics of the elastic wave filter devices according to the example and the comparative example. Fig. 6 is a graph schematically illustrating the impedance characteristics of the series arm resonators and the parallel arm resonators according to the example and the comparative example. Fig. 6 illustrates the impedance characteristics of each series arm resonator and parallel arm resonator. The elastic wave filter device according to the comparative example and the series arm resonator according to the comparative example are elastic wave filter devices and series arm resonators, respectively, that do not include the capacitive element 40.

[0041] The vertical axis of the graph shown in Fig. 5 represents the pass characteristic (level (dB) of the S parameter S21). The vertical axis of the graph shown in Fig. 6 represents the impedance level (dB). The horizontal axis of the graphs shown in Figs. 5 and 6 represents the frequency.

[0042] 6, the series arm resonator S1 according to the example has a smaller fractional bandwidth than the series arm resonator S11 according to the comparative example because the series arm resonator S1 has the capacitive element 40 connected in parallel. Furthermore, the attenuation pole of the series arm resonator S1 according to the example is shifted to a lower frequency side than the series arm resonator S11 according to the comparative example.

[0043] The attenuation pole of the series arm resonator S1 is located on the higher frequency side compared to the parallel arm resonators P1, P2, etc.

[0044] 5 , the acoustic wave filter device 10 according to the embodiment has the capacitive element 40 connected in parallel to the series arm resonator S1, and therefore, compared to the comparative example, the pass characteristics on the high-frequency side of the pass band can be adjusted more effectively. Furthermore, the capacitive element 40 is connected in parallel to the series arm resonator S1, which has the lowest frequency among the multiple series arm resonators S1, S2, S3, S4, S5, and S6, and therefore the pass characteristics on the high-frequency side can be adjusted more effectively.

[0045] 4 , the capacitive element 40 is provided on the lid 70 and is connected to the series arm resonator S1 formed on the support member 13 side by inter-element connection electrodes 58 and 59. This allows the acoustic wave filter device 10 to be more compact than a configuration in which the capacitive element 40 is provided on the support member 13 side.

[0046] In other words, because the capacitive element 40 is provided on the lid 70, there is no need to secure additional space on the support member 13 for providing the capacitive element 40. Therefore, the acoustic wave filter device 10 can adjust the pass characteristics by providing the capacitive element 40 while maintaining the element size of each resonator. Furthermore, the capacitive element 40 is provided on the lid 70, which has sufficient space for providing the capacitive element 40. This ensures flexibility in the shape and placement of the capacitive element 40, and allows a predetermined capacitance corresponding to the required pass characteristics to be added to the series arm resonator S1.

[0047] Furthermore, in a resonator having a membrane structure, heat generated in the excitation region 21 may be trapped within the cavity 14. In the acoustic wave filter device 10 of this preferred embodiment, the capacitor 40 is connected to the series arm resonator S1, so a heat transfer path (first heat transfer path) is formed from the upper electrode 31 to the lid 70 through the inter-element connecting electrode 58, the connecting wiring 45, and the capacitor 40. In addition, a heat transfer path (second heat transfer path) is formed from the lower electrode 32 to the lid 70 through the inter-element connecting electrode 59, the connecting wiring 46, and the capacitor 40.

[0048] As described above, the lid portion 70 is made of a material such as silicon (Si), and has a higher thermal conductivity than the insulating layer 12. This allows heat generated in the excitation region 21 to be transferred to the lid portion 70 through the two heat transfer paths described above and dissipated to the outside. Furthermore, the inter-element connection electrodes 58, 59 that form the two heat transfer paths are located closer to the excitation region 21 than the connection member 72, so that heat generated in the excitation region 21 can be efficiently transferred to the lid portion 70.

[0049] Furthermore, the capacitive element 40 is connected to the input terminal 61 to which a signal is input among the multiple resonators, and is provided corresponding to the series arm resonator S1 that is closest to the input terminal 61. That is, the capacitive element 40 is provided corresponding to the series arm resonator S1, which generates a larger amount of heat than the parallel arm resonators P1, P2, P3, P4, and P5, and therefore can efficiently dissipate heat generated in the excitation region 21 to the outside.

[0050] Although the present embodiment illustrates a configuration in which the capacitive element 40 is provided for one series arm resonator S1, this is not limiting. The acoustic wave filter device 10 may include multiple capacitive elements 40, and two or more of the multiple series arm resonators S1, S2, S3, S4, S5, and S6 may each have a capacitive element 40. Alternatively, a capacitive element 40 may also be provided for each of the parallel arm resonators P1, P2, P3, P4, and P5, as necessary.

[0051] Second Preferred Embodiment Fig. 7 is a plan view illustrating an acoustic wave filter device according to a second preferred embodiment of the present invention. Fig. 8 is a cross-sectional view illustrating an acoustic wave filter device according to the second preferred embodiment of the present invention. As shown in Figs. 7 and 8, an acoustic wave filter device 10A according to the second preferred embodiment of the present invention has a different configuration from the first preferred embodiment of the present invention in that it includes a shield electrode 57.

[0052] The shield electrode 57 is provided on the upper surface of the lid 70 (the surface opposite to the surface facing the first main surface 20a of the piezoelectric layer 20) and is arranged in a region overlapping with the capacitive element 40. That is, the shield electrode 57 is provided corresponding to the series arm resonator S1 of the multiple resonators and is arranged in a region overlapping with the excitation region 21 of the series arm resonator S1. The shield electrode 57 is connected to a ground terminal 63 and is supplied with a reference potential (e.g., ground potential).

[0053] The shield electrode 57 suppresses external noise from entering the capacitive element 40 and the excitation region 21 from the lid 70. This allows the acoustic wave filter device 10A to suppress degradation of the pass characteristics caused by external noise.

[0054] Furthermore, the capacitive element 40 and the shield electrode 57 are provided corresponding to at least the series arm resonator S1, among the plurality of series arm resonators, that is connected to the input terminal 61. Therefore, heat generated in the excitation region 21 is transferred to the lid 70 through the two heat transfer paths described above, and is efficiently dissipated to the outside by the shield electrode 57. In this case, the shield electrode 57 is preferably made of a material having a higher thermal conductivity than the lid 70.

[0055] The shield electrode 57 is connected to an independent ground terminal 63 (a ground terminal 63 that is not connected to other resonators). However, the invention is not limited to this, and the shield electrode 57 may be connected to a ground terminal 63 that is common to other resonators. Furthermore, although the shield electrode 57 has a substantially rectangular shape in a plan view, the invention is not limited to this, and the shield electrode 57 may have other shapes, such as a polygonal shape or a circular shape.

[0056] Although the second embodiment illustrates a configuration in which the capacitive element 40 and the shield electrode 57 are provided for one series arm resonator S1, this is not limiting. The acoustic wave filter device 10A may include a plurality of capacitive elements 40 and a plurality of shield electrodes 57. Two or more of the series arm resonators S1, S2, S3, S4, S5, and S6 may each be provided with a capacitive element 40 and a shield electrode 57. Alternatively, the capacitive element 40 and the shield electrode 57 may also be provided for the parallel arm resonators P1, P2, P3, P4, and P5, as necessary.

[0057] Third Preferred Embodiment Fig. 9 is a plan view showing a portion of an acoustic wave filter device according to a third preferred embodiment of the present invention. Fig. 10 is a cross-sectional view taken along the line XX' in Fig. 9. As shown in Figs. 9 and 10, an acoustic wave filter device 10B according to the third preferred embodiment of the present invention has a different configuration from the first preferred embodiment of the present invention in that it includes a high thermal conductivity layer 22.

[0058] 9 , the high thermal conductivity layers 22 are provided corresponding to the series arm resonators S1, S2, and S3 among the multiple series arm resonators that are closest to the input terminal 61. The high thermal conductivity layers 22 are provided around the excitation regions 21 of each of the series arm resonators S1, S2, and S3 and are provided in close proximity to the excitation regions 21.

[0059] 10 shows a cross-sectional view of the series arm resonator S1 among the multiple series arm resonators. However, the cross-sectional views of the series arm resonators S2 and S3 are similar to that of the series arm resonator S1, and the description of the series arm resonator S1 is also applicable to the series arm resonators S2 and S3.

[0060] 10, the high thermal conductivity layer 22 is provided on the insulating layer 12 of the support member 13 in the same layer as the piezoelectric layer 20. The high thermal conductivity layer 22 has a thermal conductivity higher than that of the piezoelectric layer 20. The high thermal conductivity layer 22 is made of, for example, beryllium oxide (BeO), aluminum nitride (AlN), silicon carbide (SiC), boron nitride (BN), aluminum oxide (Al ２ O ３ The high thermal conductivity layer 22 is not limited to a single layer, but may be a laminated film in which a plurality of layers are stacked.

[0061] Specifically, lithium niobate (LiNbO ３ The thermal conductivity of lithium tantalate (LiTaO) is, for example, about 4.6 W / k / m. ３ The thermal conductivity of aluminum nitride (AlN) is, for example, about 180 W / k / m. The thermal conductivity of silicon carbide (SiC) is, for example, about 70 W / k / m. The thermal conductivity of boron nitride (BN) is, for example, about 60 W / k / m. Aluminum oxide (Al ２ O ３ ) has a thermal conductivity of, for example, about 25 W / k / m.

[0062] The piezoelectric layer 20 is provided in a region overlapping with the excitation region 21 where at least the lower electrode 32 and the upper electrode 31 are stacked. The high thermal conductivity layer 22 is provided in a region surrounding the excitation region 21. More specifically, the high thermal conductivity layer 22 is stacked on a portion of the lower electrode 32 that does not overlap with the excitation region 21, and is also stacked on a portion of the upper electrode 31 that does not overlap with the excitation region 21.

[0063] A side surface 22s of the high thermal conductivity layer 22 that contacts the piezoelectric layer 20 is provided close to the excitation region 21. The side surface 22s of the high thermal conductivity layer 22 is located between the inter-element connection electrodes 58, 59 and the excitation region 21. In other words, the high thermal conductivity layer 22 is provided in a region that overlaps with the inter-element connection electrode 58 (first inter-element connection electrode) that electrically connects the connection wiring 45 connected to the capacitance element 40 to the upper electrode 31. The high thermal conductivity layer 22 is also provided around the inter-element connection electrode 59 (second inter-element connection electrode) that electrically connects the connection wiring 46 connected to the capacitance element 40 to the lower electrode 32.

[0064] Furthermore, the high thermal conductivity layer 22 extends to a region overlapping with the connecting member 72 arranged between the lid portion 70 and the support member 13. The high thermal conductivity layer 22 extends at least to a position directly below the connecting member 72 and is connected to the lower part of the connecting member 72. As a result, the high thermal conductivity layer 22 is connected to the terminals 60 and bumps 53 provided on the upper surface of the lid portion 70 through the connecting member 72 and the vias 71.

[0065] With this configuration, a heat transfer path (first heat transfer path) is formed from the piezoelectric layer 20 in the excitation region 21 through the high thermal conductivity layer 22 on the left side in Fig. 10 to the upper electrode 31, the inter-element connecting electrode 58, the connection wiring 45, the capacitance element 40, and the lid portion 70. In addition, a heat transfer path (second heat transfer path) is formed from the piezoelectric layer 20 and the lower electrode 32 in the excitation region 21 through the high thermal conductivity layer 22 on the right side in Fig. 10 to the inter-element connecting electrode 59, the connection wiring 46, the capacitance element 40, and the lid portion 70.

[0066] 10, a heat transfer path (third heat transfer path) is formed from the piezoelectric layer 20 in the excitation region 21 through the high thermal conductivity layer 22 on the left side in Fig. 10 to the connecting member 72, the via 71, the terminal 60 (input terminal 61), and the bump 53. Also, a heat transfer path (fourth heat transfer path) is formed from the piezoelectric layer 20 in the excitation region 21 and the lower electrode 32 through the high thermal conductivity layer 22 on the right side in Fig. 10 to the connecting member 72, the via 71, the terminal 60 (ground terminal 63), and the bump 53.

[0067] As a result, in this embodiment, the heat generated in the excitation region 21 is transferred to the upper surface of the lid 70 through the four heat transfer paths, and is efficiently dissipated to the outside. Therefore, the acoustic wave filter device 10B can improve the heat dissipation performance of the heat generated in the excitation region 21.

[0068] 9 , the high thermal conductivity layer 22 is provided on the series arm resonators S1, S2, and S3 that are close to the input terminal 61, i.e., the series arm resonators S1, S2, and S3 that generate relatively large amounts of heat in the excitation region 21. This enables the acoustic wave filter device 10B to effectively improve the heat dissipation performance of the multiple resonators as a whole.

[0069] This embodiment can be combined with the second embodiment described above. That is, the acoustic wave filter device 10B may have a high thermal conductivity layer 22 provided around the excitation region 21 and a shield electrode 57 provided on the upper surface of the lid 70. In this case, the acoustic wave filter device 10B can have even better heat dissipation properties.

[0070] 11 is a plan view illustrating a portion of an acoustic wave filter device according to a modification of the third embodiment. As illustrated in Fig. 11 , an acoustic wave filter device 10C according to the modification of the third embodiment differs from the third embodiment in that high thermal conductivity layers 22 are provided in the series arm resonators S1, S2, S3, S4, S5, and S6 and the parallel arm resonators P1, P2, P3, P4, and P5.

[0071] More specifically, the high thermal conductivity layer 22 is provided around the excitation regions 21 of each of the series arm resonators S1, S2, S3, S4, S5, and S6 and the parallel arm resonators P1, P2, P3, P4, and P5. In other words, the high thermal conductivity layer 22 is provided to cover almost the entire surface of the support member 13 except for the excitation regions 21 of each resonator.

[0072] As a result, in this embodiment, the heat dissipation performance can be improved in each of the plurality of series arm resonators S1, S2, S3, S4, S5, and S6 and the plurality of parallel arm resonators P1, P2, P3, P4, and P5.

[0073] 9 to 11, the high thermal conductivity layers 22 are formed in a continuous arrangement pattern across a plurality of resonators, but the arrangement pattern of the high thermal conductivity layers 22 is not limited to the examples shown in the above-mentioned Figures 9 to 11 and can be changed as appropriate. For example, a plurality of high thermal conductivity layers 22 may be provided at intervals for each resonator or for each plurality of resonators.

[0074] 12 is a cross-sectional view of an acoustic wave filter device according to a fourth preferred embodiment of the present invention. As shown in FIG. 12 , an acoustic wave filter device 10D according to the fourth preferred embodiment of the present invention differs from the first preferred embodiment of the present invention in that the capacitance element 40A is a stacked type having a multilayer electrode.

[0075] The capacitance element 40A includes a first electrode 47, a second electrode 48, and an insulating layer 49. The first electrode 47 is disposed opposite the second electrode 48 with the insulating layer 49 sandwiched therebetween. The capacitance element 40A is formed by laminating the first electrode 47, the insulating layer 49, and the second electrode 48 in this order on the surface (lower surface) of the lid 70 that faces the support member 13. In other words, the capacitance element 40A is configured as a parallel plate capacitor. The insulating layer 49 may be made of, for example, Ta. ２ O ５ , SiO ２ , ZnO, and other dielectric materials.

[0076] The first electrode 47 is connected to the upper electrode 31 via a connection wiring 45 and an inter-element connection electrode 58. The second electrode 48 is connected to the lower electrode 32 via a connection wiring 46 and an inter-element connection electrode 59.

[0077] In the present embodiment, the first electrode 47 is provided in contact with the lid portion 70, and the second electrode 48 is stacked on the lid portion 70 with the insulating layer 49 and the first electrode 47 sandwiched therebetween. That is, the contact area between the first electrode 47 and the lid portion 70 is larger than the contact area between the second electrode 48 and the lid portion 70. Therefore, the heat transfer path (first heat transfer path) from the excitation region 21 to the lid portion 70 via the upper electrode 31, the inter-element connecting electrode 58, the connection wiring 45, and the first electrode 47 has higher heat dissipation properties than the heat transfer path (second heat transfer path) from the excitation region 21 to the lid portion 70 via the lower electrode 32, the inter-element connecting electrode 59, the connection wiring 46, and the second electrode 48.

[0078] Therefore, by adopting a configuration in which the upper electrode 31 and the inter-element connecting electrode 58 are connected to the input terminal 61, the acoustic wave filter device 10D can dissipate heat preferentially along the first heat transfer path.

[0079] The capacitance element 40A has two layers of electrodes (a first electrode 47 and a second electrode 48), but is not limited to this and may have a configuration in which three or more layers of electrodes are stacked. The configuration of this embodiment can be combined with the configurations of the second embodiment, the third embodiment, and the modified examples described above.

[0080] The above-described embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The present invention may be modified or improved without departing from the spirit and scope of the present invention, and equivalents thereof are also included in the present invention.

[0081] The present disclosure may also have the following configurations.

[0082] (1) An acoustic wave filter device comprising: a series arm resonator connected between an input terminal and an output terminal; a parallel arm resonator connected between a node on a path connecting the input terminal and the output terminal and a ground terminal; and a capacitive element connected between the input terminal and the output terminal and in parallel with the series arm resonator. (2) The acoustic wave filter device according to (1), comprising a plurality of the series arm resonators, and the capacitive element is connected in parallel with one of the plurality of series arm resonators connected to the input terminal. (3) The acoustic wave filter device according to (1) or (2), comprising: a shield electrode connected to the ground terminal and arranged opposite to the capacitive element. (4) The acoustic wave filter device according to any one of (1) to (3), comprising: a piezoelectric layer having a first main surface and a second main surface opposite to the first main surface; a support member facing the second main surface of the piezoelectric layer; and a lid facing the first main surface of the piezoelectric layer, wherein the series arm resonator and the parallel arm resonator each include the piezoelectric layer, an upper electrode provided on the first main surface of the piezoelectric layer, and a lower electrode provided on the second main surface of the piezoelectric layer, and the capacitive element is provided on a surface of the lid facing the first main surface of the piezoelectric layer. (5) The acoustic wave filter device according to (4), comprising: a first inter-element connection electrode electrically connecting one end of the capacitive element to one of the upper electrode and the lower electrode; and a second inter-element connection electrode electrically connecting the other end of the capacitive element to the other of the upper electrode and the lower electrode. (6) The acoustic wave filter device according to (4) or (5), further comprising: a shield electrode provided on the cover portion on the opposite side of a surface of the piezoelectric layer facing the first main surface, the shield electrode being arranged in a region overlapping with the capacitive element. (7) The acoustic wave filter device according to any one of (4) to (6), further comprising: a high thermal conductivity layer provided on the support member in the same layer as the piezoelectric layer, the high thermal conductivity layer having a thermal conductivity higher than that of the piezoelectric layer, the piezoelectric layer being provided in a region overlapping with an excitation region where at least the lower electrode, the piezoelectric layer, and the upper electrode are stacked, and the high thermal conductivity layer being provided in a region surrounding the excitation region.(8) The acoustic wave filter device according to (4), comprising: a high thermal conductivity layer provided on the support member in the same layer as the piezoelectric layer, the high thermal conductivity layer having a thermal conductivity higher than that of the piezoelectric layer, a first inter-element connection electrode electrically connecting one end of the capacitive element to the upper electrode, and a second inter-element connection electrode electrically connecting the other end of the capacitive element to the lower electrode, the piezoelectric layer being provided in a region overlapping with an excitation region in which at least the lower electrode, the piezoelectric layer, and the upper electrode are stacked, the high thermal conductivity layer being provided in a region surrounding the excitation region and surrounding the second inter-element connection electrode. (9) The acoustic wave filter device according to (7) or (8), comprising: a connecting member disposed between the lid and the support member, and a terminal provided on a surface of the lid opposite to the piezoelectric layer, the terminal connected to the connecting member through a via hole penetrating the lid, the high thermal conductivity layer being provided in a region overlapping with the connecting member. (10) The acoustic wave filter device according to any one of (4) to (9), wherein the piezoelectric layer includes single-crystal lithium niobate or lithium tantalate.

[0083] REFERENCE SIGNS LIST 10, 10A, 10B, 10C, 10D Acoustic wave filter device 11 Support substrate 12 Insulating layer 13 Support member 14 Cavity portion 20 Piezoelectric layer 20a First main surface 20b Second main surface 21 Excitation region 22 High thermal conductivity layer 31 Upper electrode 32 Lower electrode 40, 40A Capacitor element 53 Bump 57 Shield electrode 58, 59 Inter-element connection electrode 60 Terminal 61 Input terminal 62 Output terminal 63 Ground terminal 70 Lid portion 71 Via 72 Connection member 74, 75 Sealing portion S1, S2, S3, S4, S5, S6 Series arm resonator P1, P2, P3, P4, P5 Parallel arm resonator

Claims

1. An elastic wave filter device comprising: a series arm resonator connected between an input terminal and an output terminal; a parallel arm resonator connected between a node on a path connecting the input terminal and the output terminal and a ground terminal; and a capacitive element connected between the input terminal and the output terminal and in parallel with the series arm resonator.

2. The elastic wave filter device according to claim 1, comprising a plurality of the series arm resonators, wherein the capacitive element is connected in parallel with one of the plurality of series arm resonators that is connected to the input terminal.

3. The acoustic wave filter device according to claim 1, further comprising a shield electrode connected to the ground terminal and disposed opposite the capacitive element.

4. An elastic wave filter device according to any one of claims 1 to 3, comprising: a piezoelectric layer having a first main surface and a second main surface opposite the first main surface; a support member facing the second main surface of the piezoelectric layer; and a lid facing the first main surface of the piezoelectric layer, wherein the series arm resonator and the parallel arm resonator each include the piezoelectric layer, an upper electrode provided on the first main surface of the piezoelectric layer, and a lower electrode provided on the second main surface of the piezoelectric layer, and the capacitive element is provided on a surface of the lid facing the first main surface of the piezoelectric layer.

5. An elastic wave filter device as described in claim 4, comprising: a first inter-element connection electrode electrically connecting one end side of the capacitance element and one of the upper electrode and the lower electrode; and a second inter-element connection electrode electrically connecting the other end side of the capacitance element and the other of the upper electrode and the lower electrode.

6. The elastic wave filter device according to claim 4 or 5, further comprising a shield electrode provided on the side of the lid opposite the surface facing the first main surface of the piezoelectric layer and arranged in a region overlapping with the capacitive element.

7. An elastic wave filter device as claimed in any one of claims 4 to 6, further comprising a high thermal conductivity layer provided on the support member in the same layer as the piezoelectric layer and having a thermal conductivity higher than that of the piezoelectric layer, the piezoelectric layer being provided in a region overlapping with at least an excitation region in which the lower electrode, the piezoelectric layer and the upper electrode are stacked, and the high thermal conductivity layer being provided in a region surrounding the excitation region.

8. An elastic wave filter device as described in claim 4, comprising: a high thermal conductivity layer provided on the support member in the same layer as the piezoelectric layer, the high thermal conductivity layer having a thermal conductivity higher than that of the piezoelectric layer; a first inter-element connection electrode electrically connecting one end side of the capacitive element and the upper electrode; and a second inter-element connection electrode electrically connecting the other end side of the capacitive element and the lower electrode, wherein the piezoelectric layer is provided in a region overlapping with at least an excitation region in which the lower electrode, the piezoelectric layer and the upper electrode are stacked, and the high thermal conductivity layer is provided in a region surrounding the excitation region and around the second inter-element connection electrode.

9. An elastic wave filter device as described in claim 7 or claim 8, comprising: a connecting member disposed between the lid portion and the support member; and a terminal provided on the surface of the lid portion opposite the piezoelectric layer and connected to the connecting member through a via that passes through the lid portion, wherein the high thermal conductivity layer is provided in an area that overlaps with the connecting member.

10. The acoustic wave filter device according to any one of claims 4 to 9, wherein the piezoelectric layer contains single crystal lithium niobate or lithium tantalate.

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