Elastic wave filter device

Abstract

An elastic wave filter device 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 capacitor element connected between the input terminal and the output terminal and connected in parallel with the series arm resonator. The elastic wave filter device has a plurality of series arm resonators, and a capacitance element is connected in parallel to a series arm resonator connected to an input terminal among the plurality of series arm resonators.

Description

Technical Field

[0001] This invention relates to elastic wave filter devices. Background Technology

[0002] Patent documents 1 to 3 describe elastic wave devices (referred to as elastic wave devices in patent document 2 and as motor components in patent document 3) that include a SAW (Surface Acoustic Wave) element utilizing surface waves or a BAW (Bulk Acoustic Wave) element utilizing bulk waves. For example, in the elastic wave device of patent document 1, a structure in which an LC circuit is provided in the covering member is disclosed.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2017 / 110308

[0006] Patent Document 2: Japanese Patent Application Publication No. 2016-152612

[0007] Patent Document 3: Japanese Patent Publication No. 2010-526456 Summary of the Invention

[0008] The problem the invention aims to solve

[0009] In such elastic wave devices, miniaturization and good tuning of transmission characteristics are required.

[0010] The purpose of this invention is to provide an elastic wave filter device that can be miniaturized and has well-adjusted transmission characteristics.

[0011] Technical solutions for solving the problem

[0012] One type of elastic wave filter device includes: a series arm resonator connected between an input terminal and an output terminal; a parallel arm resonator connected between a node on the path connecting the input terminal and the output terminal and a ground terminal; and a capacitor element connected between the input terminal and the output terminal and connected in parallel with the series arm resonator.

[0013] Invention Effects

[0014] The elastic wave filter device according to the present invention can be miniaturized and its transmission characteristics can be well adjusted. Attached Figure Description

[0015] Figure 1This is a circuit diagram showing the elastic wave filter device according to the first embodiment.

[0016] Figure 2 This is a top view showing the elastic wave filter device according to the first embodiment.

[0017] Figure 3 This is a top view showing a portion of the elastic wave filter device according to the first embodiment.

[0018] Figure 4 yes Figure 3 Sectional view of IV-IV'.

[0019] Figure 5 The graph schematically illustrates the transmission characteristics of the elastic wave filter device involved in the embodiments and comparative examples.

[0020] Figure 6 The graphs schematically illustrate the impedance characteristics of the series arm resonator and the parallel arm resonator involved in the embodiments and comparative examples.

[0021] Figure 7 This is a top view showing the elastic wave filter device according to the second embodiment.

[0022] Figure 8 This is a cross-sectional view showing the elastic wave filter device according to the second embodiment.

[0023] Figure 9 This is a top view showing a portion of the elastic wave filter device according to the third embodiment.

[0024] Figure 10 yes Figure 9 X-X' sectional view.

[0025] Figure 11 This is a top view showing a portion of the elastic wave filter device according to a variation of the third embodiment.

[0026] Figure 12 This is a cross-sectional view showing the elastic wave filter device according to the fourth embodiment. Detailed Implementation

[0027] Hereinafter, embodiments of the present disclosure will be described in detail based on the accompanying drawings. However, the present disclosure is not limited to these embodiments. Furthermore, the embodiments described in this disclosure are illustrative, and partial substitutions or combinations of structures can be made between different embodiments. From the modified examples and the second embodiment onwards, descriptions of matters common to the first embodiment are omitted, and only the differences are described. In particular, the same effects based on the same structure will not be mentioned repeatedly in each embodiment.

[0028] (First Embodiment)

[0029] Figure 1 This is a circuit diagram showing the elastic wave filter device according to the first embodiment. The resonator constituting the elastic wave filter device 10 according to the first embodiment is a bulk wave resonator, that is, a BAW (Bulk Acoustic Wave) element.

[0030] like Figure 1 As shown, the elastic wave filter device 10 according to the first embodiment includes a plurality of series-arm resonators S1, S2, S3, S4, S5, S6, a plurality of parallel-arm resonators P1, P2, P3, P4, P5, and a capacitor element 40. The plurality of series-arm resonators S1, S2, S3, S4, S5, S6 are connected in series in the signal path between the input terminal 61 and the output terminal 62. The plurality of parallel-arm resonators P1, P2, P3, P4, 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 elastic wave filter device 10 according to the first embodiment is called a trapezoidal filter.

[0031] One terminal of each of the series-connected series-arm resonators S1, S2, S3, S4, S5, and S6 is electrically connected to the input terminal 61, and the other terminal is electrically connected to the output terminal 62. One terminal of the parallel-arm resonator P1 is electrically connected to a node in the signal path connecting series-arm resonators S1 and S2, and the other terminal is electrically connected to the ground terminal 63. One terminal of the parallel-arm resonator P2 is electrically connected to a node in the signal path connecting series-arm resonators S2 and S3, and the other terminal is electrically connected to the ground terminal 63.

[0032] One terminal of the parallel arm resonator P3 is electrically connected to a node in 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 in 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 in the signal path connecting the series arm resonators S5 and S6, and the other terminal is electrically connected to the ground terminal 63.

[0033] Capacitor element 40 is connected in parallel with series arm resonator S1. That is, capacitor element 40 is connected between input terminal 61 and output terminal 62, and is connected in parallel with series arm resonator S1. More specifically, one end of capacitor element 40 is electrically connected to a node on the signal path connecting input terminal 61 and series arm resonator S1. The other end of capacitor element 40 is electrically connected to a node on the signal path connecting series arm resonators S2 and S3.

[0034] Next, refer to Figures 2 to 4 An example of the structure of the elastic wave filter device 10 according to the first embodiment will be described. Figure 2 This is a top view showing the elastic wave filter device according to the first embodiment. Figure 3 This is a top view showing a portion of the elastic wave filter device according to the first embodiment. Figure 4 yes Figure 3 Sectional view IV-IV'. Additionally... Figure 3 This is a top view showing the elastic wave filter device 10 according to the first embodiment with the cover 70 removed. Furthermore, in Figure 3 In order to make the accompanying drawings easier to observe, multiple series arm resonators S1, S2, S3, S4, S5, S6 and multiple parallel arm resonators P1, P2, P3, P4, P5 are shown with shading lines.

[0035] like Figures 2 to 4 As shown, the elastic wave filter device 10 includes a support member 13, a piezoelectric layer 20, an upper electrode 31, and a lower electrode 32. The elastic wave filter device 10 also includes a cover 70 disposed on the upper side of the resonator, a capacitor element 40, inter-element connecting electrodes 58 and 59, a terminal 60, a bump 53, a through hole 71, a connecting member 72, and sealing portions 74 and 75.

[0036] In the following description, the thickness direction of the piezoelectric layer 20 is defined as the Z direction, the direction orthogonal to the Z direction is defined as the X direction, and the direction orthogonal to both the Z and X directions is defined as the Y direction. The X and Y directions are parallel to the surface (first main surface 20a) of the piezoelectric layer 20. Furthermore, in the following description, "top view" refers to the arrangement when viewed from a direction perpendicular to the first main surface 20a of the piezoelectric layer 20 (Z direction).

[0037] like Figure 2As shown, multiple terminals 60 (input terminal 61, output terminal 62, and multiple ground terminals 63) constituting the elastic wave filter device 10 are provided on the upper surface of the cover 70. The input terminal 61 is located at the lower left of the cover 70. The output terminal 62 is located at the upper right of the cover 70. The terminals 60 other than the input terminal 61 and the output terminal 62 are ground terminals 63. Furthermore, a capacitor element 40 is provided on the lower surface of the cover 70 opposite to the support member 13, in conjunction with the series arm resonator S1 (see reference 1). Figure 3 (The overlapping positions.)

[0038] like Figure 3 As shown, multiple series-arm resonators S1, S2, S3, S4, S5, S6 and multiple parallel-arm resonators P1, P2, P3, P4, P5 constituting the elastic wave filter device 10 are provided on the support member 13. Furthermore, in the following description, unless it is necessary to distinguish between the multiple series-arm resonators S1, S2, S3, S4, S5, S6 and the multiple parallel-arm resonators P1, P2, P3, P4, P5, they will simply be referred to as resonators.

[0039] Each resonator is connected via a node, a connecting member 72, and a via 71 (see reference 13) on the signal path formed on the support member 13. Figure 4 It is electrically connected to each terminal 60 on the cover 70.

[0040] like Figure 2 as well as Figure 3 As shown, a sealing portion 74 is provided on the outer edge of the cover portion 70. Furthermore, a sealing portion 75 is provided on the outer edge of the support member 13. The sealing portions 74 and 75, viewed from above, surround the plurality of resonators and the plurality of terminals 60 in a frame-like configuration. The cover portion 70 and the support member 13 are arranged opposite each other, and the sealing portions 74 and 75 overlap and engage, thereby sealing the space surrounded by the cover portion 70, the support member 13, and the sealing portions 74 and 75.

[0041] in addition, Figure 2 as well as Figure 3 The arrangement of the multiple resonators, multiple terminals 60, and various wirings connecting them shown is just an example and can be varied appropriately. For example, the multiple terminals 60 may be arranged along the outer edge of the cover 70, but this is not a limitation; they may also be arranged in the center of the cover 70.

[0042] Next, refer to Figure 4 The stacked structure of the elastic wave filter device 10 will be described. Figure 4 The stacked structure of the series arm resonator S1 among multiple resonators is described. However, besides... Figure 4Besides the structure of the capacitor element 40 and the connecting electrodes 58 and 59 between the elements, the description of the series arm resonator S1 can also be applied to other resonators.

[0043] like Figure 4 As shown, a lower electrode 32, a piezoelectric layer 20, and an upper electrode 31 are stacked sequentially on the support member 13, thereby forming a series arm resonator S1.

[0044] The support member 13 is disposed opposite to 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 includes silicon (Si), quartz, etc. The insulating layer 12 is disposed between the support substrate 11 and the piezoelectric layer 20. The insulating layer 12 is formed of an insulating material such as silicon oxide. Alternatively, the support member 13 may also have a structure in which the insulating layer 12 is not present, and the piezoelectric layer 20 is disposed on the support substrate 11.

[0045] A cavity 14 (void) is formed on the surface of the support member 13 (insulating layer 12) opposite to the second main surface 20b of the piezoelectric layer 20. The cavity 14 is configured to overlap with the excitation region 21 of the resonator, which is formed by overlapping the piezoelectric layer 20, the upper electrode 31, and the lower electrode 32 when viewed from above. As a result, bulk waves are reflected by the cavity 14.

[0046] The piezoelectric layer 20 is 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 a substrate containing a single crystal of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3). The thickness of the piezoelectric layer 20 is not particularly limited, but is preferably 1 μm or less.

[0047] The upper electrode 31 is disposed on the first main surface 20a of the piezoelectric layer 20. The upper electrode 31 has a portion that overlaps with the cavity 14 of the insulating layer 12 and a portion that extends outward from the cavity 14.

[0048] The lower electrode 32 is disposed on the second main surface 20b of the piezoelectric layer 20, and at least a portion of it is disposed in the region overlapping with the upper electrode 31. The lower electrode 32 has a portion that overlaps with the cavity 14 and the upper electrode 31, and a portion that does not overlap with the cavity 14 and the upper electrode 31 and extends outward from the cavity 14. In addition, a sealing layer of Ti, NiCr, etc. may exist between the lower electrode 32 and the insulating layer 12.

[0049] The elastic wave filter device 10 has a so-called diaphragm structure in which a cavity 14 (void) is provided on the second main 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. As a result, bulk waves 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 plan view is sometimes described as the excitation region 21 of the resonator.

[0050] Although Figure 4 The diagram is omitted, but for example, the portion of the upper electrode 31 extending outward from the cavity 14 (wiring portion) is electrically connected to the input terminal 61, and the portion of the lower electrode 32 extending outward from the cavity 14 (wiring portion) is electrically connected to the series arm resonator S2 and the parallel arm resonator P1. However, this is not a limitation; the structure could also be such that 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.

[0051] The upper electrode 31 and the lower electrode 32 are formed of metals such as aluminum (Al), platinum (Pt), copper (Cu), tungsten (W), and molybdenum (Mo), or alloys containing at least one of these materials. The upper electrode 31 and the lower electrode 32 may also be a laminated film.

[0052] The cover portion 70 is disposed opposite to the first main surface 20a of the piezoelectric layer 20. A connecting member 72 is provided between the cover portion 70 and the first main surface 20a of the piezoelectric layer 20. The cover portion 70 is formed of, for example, the same material as the support substrate 11, such as silicon (Si) or quartz. In addition, multiple terminals 60 and bumps 53 are provided on the upper surface of the cover portion 70 (on the side opposite to the surface opposite to the first main surface 20a of the piezoelectric layer 20).

[0053] One of the upper electrode 31 and the lower electrode 32 constituting the series arm resonator S1 is electrically connected to the input terminal 61 provided on the upper surface of the cover 70 via the connecting member 72 and the through hole 71 penetrating the cover 70.

[0054] Capacitor element 40 is disposed on the surface of cover 70 opposite to the first main surface 20a of piezoelectric layer 20. Capacitor element 40 is disposed in the region overlapping with the excitation region 21 of series arm resonator S1.

[0055] like Figure 2As shown, capacitor element 40 has IDT (Interdigital Transducer) electrodes and is formed in a planar shape. Capacitor element 40 has electrode fingers 41 and 42 and busbar electrodes 43 and 44. Multiple electrode fingers 41 extend in the Y direction, with one end connected to busbar electrode 43 in the extending direction. Multiple electrode fingers 42 extend in the Y direction, with the other end connected to busbar electrode 44 in the extending direction. The multiple electrode fingers 41 and 42 are arranged alternately in the X direction at intervals. Busbar electrode 43 and busbar electrode 44 extend in the X direction and are separately arranged in the Y direction. Multiple electrode fingers 41 and 42 are arranged between busbar electrode 43 and busbar electrode 44. A capacitance of capacitor element 40 is formed between the separately arranged multiple electrode fingers 41 and 42.

[0056] A connecting wire 45 is connected to the busbar electrode 43 of the capacitor element 40. A connecting wire 46 is connected to the busbar electrode 44 of the capacitor element 40.

[0057] like Figure 4 As shown, inter-element connection electrodes 58 and 59 are disposed between the support member 13 and the cover portion 70. Inter-element connection electrode 58 (the first inter-element connection electrode) electrically connects the connection wiring 45, which is connected to one end of the capacitor element 40, and the upper electrode 31. Inter-element connection electrode 59 (the second inter-element connection electrode) electrically connects the connection wiring 46, which is connected to the other end of the capacitor element 40, and 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.

[0058] With this structure, the capacitor element 40 is connected in parallel to the series arm resonator S1 via connecting wires 45 and 46 and inter-element connecting electrodes 58 and 59. Furthermore, the connecting wires 45 and 46 are the same as the wiring section described above, and the material used for the wiring section can also be applied to the connecting wires 45 and 46.

[0059] Figure 5 The graph schematically illustrates the transmission characteristics of the elastic wave filter device involved in the embodiments and comparative examples. Figure 6 These are schematic graphs illustrating the impedance characteristics of the series-arm resonator and the parallel-arm resonator involved in the embodiments and comparative examples. Figure 6 The impedance characteristics of each series arm resonator and the parallel arm resonator are illustrated in the examples. Furthermore, the elastic wave filter device and the series arm resonator involved in the comparative examples are an elastic wave filter device without the capacitor element 40 and a series arm resonator, respectively.

[0060] Figure 5 The vertical axis of the graph shown is through the characteristic (the level (dB) of S-parameter S21). Figure 6 The vertical axis of the graph shown represents the impedance level (dB). Figure 5 as well as Figure 6 The horizontal axis of the graph shown represents frequency.

[0061] like Figure 6 As shown, the series arm resonator S1 of the embodiment is connected in parallel with a capacitor element 40, thus its relative bandwidth is smaller compared to the series arm resonator S11 of the comparative example. Furthermore, compared to the series arm resonator S11 of the comparative example, the attenuation electrode of the series arm resonator S1 of the embodiment is shifted towards the lower frequency side.

[0062] Furthermore, compared to parallel arm resonators P1 and P2, the attenuation pole of series arm resonator S1 is located on the high-frequency side.

[0063] like Figure 5 As shown, in the elastic wave filter device 10 of the embodiment, a capacitor element 40 is connected in parallel to the series arm resonator S1. Therefore, compared with the comparative example, it is shown that the high-frequency transmission characteristics can be adjusted in the passband. In addition, the capacitor element 40 is connected in parallel to the series arm resonator S1, which has the lowest frequency among the plurality of series arm resonators S1, S2, S3, S4, S5, and S6, so the high-frequency transmission characteristics can be well adjusted.

[0064] In addition, such as Figure 4 As shown, the capacitor element 40 is disposed on the cover portion 70 and is connected to the series arm resonator S1 formed on the support member 13 side via inter-element connecting electrodes 58 and 59. Thus, compared with the structure in which the capacitor element 40 is disposed on the support member 13 side, the elastic wave filter device 10 can be miniaturized.

[0065] In other words, because the capacitor element 40 is provided in the cover portion 70, it is not necessary to ensure a placement area for the newly provided capacitor element 40 on the support member 13 side. Therefore, the elastic wave filter device 10 can adjust the transmission characteristics by providing the capacitor element 40 while maintaining the element size of each resonator. Furthermore, the capacitor element 40 is provided in the cover portion 70, which has sufficient placement area. Therefore, the shape and placement freedom of the capacitor element 40 can be ensured, and a given capacitance corresponding to the required transmission characteristics can be added to the series arm resonator S1.

[0066] Furthermore, in resonators with diaphragm structures, heat generated in the excitation region 21 is sometimes confined within the cavity 14. In the elastic wave filter device 10 of this embodiment, a capacitor element 40 is connected to the series arm resonator S1, thus forming a heat conduction path (first heat conduction path) from the upper electrode 31 through the inter-element connecting electrode 58, the connecting wire 45, and the capacitor element 40 to the cover 70. Additionally, a heat conduction path (second heat conduction path) is formed from the lower electrode 32 through the inter-element connecting electrode 59, the connecting wire 46, and the capacitor element 40 to the cover 70.

[0067] As described above, the material of the cover 70, such as silicon (Si), has a higher thermal conductivity than the insulating layer 12. Therefore, the heat generated in the excitation region 21 can be transferred to the cover 70 and dissipated to the outside through the two heat conduction paths described above. Furthermore, the inter-element connecting electrodes 58 and 59 forming the two heat conduction paths are positioned closer to the excitation region 21 than the connecting member 72, thus enabling efficient transfer of the heat generated in the excitation region 21 to the cover 70 side.

[0068] Furthermore, the capacitor element 40 is correspondingly positioned with the series arm resonator S1, which is connected to and closest to the input terminal 61 of the input signal. That is, the capacitor element 40 is correspondingly positioned with the series arm resonator S1, which has a larger heat generation than the parallel arm resonators P1, P2, P3, P4, and P5, thus efficiently dissipating the heat generated in the excitation region 21 to the outside.

[0069] Furthermore, in this embodiment, a structure is shown in which the capacitor element 40 is correspondingly provided with one series arm resonator S1, but it is not limited to this. The elastic wave filter device 10 may also have multiple capacitor elements 40, and capacitor elements 40 may be provided for two or more of the multiple series arm resonators S1, S2, S3, S4, S5, and S6 respectively. Alternatively, parallel arm resonators P1, P2, P3, P4, and P5 may also be provided as needed.

[0070] (Second Implementation)

[0071] Figure 7 This is a top view showing the elastic wave filter device according to the second embodiment. Figure 8 This is a cross-sectional view showing the elastic wave filter device according to the second embodiment. Figure 7 as well as Figure 8 As shown, the elastic wave filter device 10A according to the second embodiment differs from the first embodiment described above in that it has a shielding electrode 57.

[0072] A shielding electrode 57 is disposed on the upper surface of the cover portion 70 (opposite to the surface opposite to the first main surface 20a of the piezoelectric layer 20) and is located in the region overlapping with the capacitor element 40. That is, the shielding electrode 57 is disposed corresponding to the series arm resonator S1 among the plurality of resonators, and is located in the region overlapping with the excitation region 21 of the series arm resonator S1. The shielding electrode 57 is connected to a ground terminal 63 and can be supplied with a reference potential (e.g., ground potential).

[0073] External noise intruding from the cover 70 toward the capacitor element 40 and the excitation region 21 can be suppressed by the shielding electrode 57. As a result, the elastic wave filter device 10A can suppress the degradation of the transmission characteristics caused by external noise.

[0074] Furthermore, the capacitor element 40 and the shielding electrode 57 are respectively provided corresponding to at least one of the series arm resonators S1 connected to the input terminal 61. Therefore, the heat generated in the excitation region 21 is transferred to the cover 70 through the two heat conduction paths described above, and is efficiently dissipated to the outside through the shielding electrode 57. In this case, the shielding electrode 57 is preferably formed of a material having a higher thermal conductivity than the cover 70.

[0075] The shielding electrode 57 is connected to a separate grounding terminal 63 (grounding terminal 63 not connected to other resonators). However, it is not limited to this; the shielding electrode 57 may also be connected to a common grounding terminal 63 with other resonators. Furthermore, the shielding electrode 57 is generally rectangular in shape when viewed from above, but it is not limited to this; it may also be polygonal, circular, or other shapes.

[0076] In addition, in the second embodiment, a structure is shown in which the capacitor element 40 and the shielding electrode 57 are respectively provided with a series arm resonator S1, but it is not limited to this. The elastic wave filter device 10A may also have multiple capacitor elements 40 and multiple shielding electrodes 57, and capacitor elements 40 and shielding electrodes 57 may be provided for two or more of the multiple series arm resonators S1, S2, S3, S4, S5, and S6 respectively. Alternatively, capacitor elements 40 and shielding electrodes 57 may also be provided for the parallel arm resonators P1, P2, P3, P4, and P5 as needed.

[0077] (Third implementation)

[0078] Figure 9 This is a top view showing a portion of the elastic wave filter device according to the third embodiment. Figure 10 yes Figure 9 The X-X' sectional view. (See example) Figure 9 as well as Figure 10As shown, the elastic wave filter device 10B according to the third embodiment differs from the first embodiment described above in that it has a high thermal conductivity layer 22.

[0079] like Figure 9 As shown, the high thermal conductivity layer 22 is disposed corresponding to the series arm resonators S1, S2, and S3, which are close to the input terminal 61 among the multiple series arm resonators. The high thermal conductivity layer 22 is disposed around the excitation region 21 of each of the series arm resonators S1, S2, and S3, and is disposed close to the excitation region 21.

[0080] exist Figure 10 The diagram shows a cross-sectional view of series arm resonator S1, one of a plurality of series arm resonators. However, the cross-sectional views of series arm resonators S2 and S3 are the same as those of series arm resonator S1, and the description of series arm resonator S1 can also be applied to series arm resonators S2 and S3.

[0081] like Figure 10 As shown, the high thermal conductivity layer 22 is disposed 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 higher thermal conductivity than the piezoelectric layer 20. The high thermal conductivity layer 22 may contain materials such as beryllium oxide (BeO), aluminum nitride (AlN), silicon carbide (SiC), boron nitride (BN), and aluminum oxide (Al2O3). The high thermal conductivity layer 22 is not limited to a single layer, but may also be a laminated film with multiple layers.

[0082] Specifically, the thermal conductivity of lithium niobate (LiNbO3) used as the piezoelectric layer 20 is, for example, around 4.6 W / k / m, and that of lithium tantalate (LiTaO3) is, for example, around 8.78 W / k / m. In contrast, the thermal conductivity of beryllium oxide (BeO) used as the material for the aforementioned high thermal conductivity layer 22 is, for example, around 265 W / k / m. Alternatively, the thermal conductivity of aluminum nitride (AlN) is, for example, around 180 W / k / m. The thermal conductivity of silicon carbide (SiC) is, for example, around 70 W / k / m. The thermal conductivity of boron nitride (BN) is, for example, around 60 W / k / m. The thermal conductivity of aluminum oxide (Al2O3) is, for example, around 25 W / k / m.

[0083] A piezoelectric layer 20 is disposed at least in the region overlapping the excitation region 21, where the lower electrode 32 and the upper electrode 31 are stacked. A high thermal conductivity layer 22 is disposed in the region surrounding the excitation region 21. More specifically, the high thermal conductivity layer 22 is stacked with portions of the lower electrode 32 that do not overlap with the excitation region 21, and also with portions of the upper electrode 31 that do not overlap with the excitation region 21.

[0084] The side 22s of the high thermal conductivity layer 22 that is in contact with the piezoelectric layer 20 is positioned close to the excitation region 21. The side 22s of the high thermal conductivity layer 22 is located between the inter-element connection electrodes 58, 59 and the excitation region 21. That is, the high thermal conductivity layer 22 is disposed in the region overlapping with the inter-element connection electrode 58 (first inter-element connection electrode) that electrically connects the connection wiring 45 connected to the capacitor element 40 and the upper electrode 31. In addition, the high thermal conductivity layer 22 is disposed around the inter-element connection electrode 59 (second inter-element connection electrode) that electrically connects the connection wiring 46 connected to the capacitor element 40 and the lower electrode 32.

[0085] Furthermore, the high thermal conductivity layer 22 extends to the region overlapping with the connecting member 72 disposed between the cover 70 and the support member 13. The high thermal conductivity layer 22 extends at least directly below the connecting member 72 and connects to the lower part of the connecting member 72. Thus, the high thermal conductivity layer 22 is connected to the terminal 60 and the protrusion 53 provided on the upper surface of the cover 70 via the connecting member 72 and the through hole 71.

[0086] Through this structure, a piezoelectric layer 20 is formed starting from the excitation region 21 and extending through... Figure 10 The high thermal conductivity layer 22 on the left side of the structure forms a heat conduction path (first heat conduction path) that reaches the upper electrode 31, the inter-element connection electrode 58, the connection wiring 45, the capacitor element 40, and the cover portion 70. Furthermore, a heat conduction path is formed from the piezoelectric layer 20 of the excitation region 21 and the lower electrode 32 through... Figure 10 The high thermal conductivity layer 22 on the right side of the middle reaches the heat conduction path (second heat conduction path) of the inter-element connecting electrode 59, the connecting wiring 46, the capacitor element 40, and the cover 70.

[0087] Furthermore, a piezoelectric layer 20 is formed starting from the excitation region 21 through... Figure 10 The high thermal conductivity layer 22 on the left side of the middle reaches the connecting member 72, the through hole 71, the terminal 60 (input terminal 61), and the bump 53 through a heat conduction path (the third heat conduction path). Furthermore, a heat conduction path is formed from the piezoelectric layer 20 of the excitation region 21 and the lower electrode 32 through... Figure 10 The high thermal conductivity layer 22 on the right side of the middle reaches the connecting member 72, the through hole 71, the terminal 60 (ground terminal 63) and the heat conduction path (fourth heat conduction path) of the bump 53.

[0088] Therefore, in this embodiment, the heat generated in the excitation region 21 is transferred to the upper surface of the cover 70 through the four heat conduction paths described above, and can be effectively dissipated to the outside. Thus, the elastic wave filter device 10B can improve the heat dissipation of the heat generated in the excitation region 21.

[0089] like Figure 9As shown, the high thermal conductivity layer 22 is disposed in the series arm resonators S1, S2, and S3 (i.e., the series arm resonators S1, S2, and S3 in the excitation region 21 that generate relatively large amounts of heat) near the input terminal 61 among the multiple series arm resonators. As a result, in the elastic wave filter device 10B, heat dissipation can be effectively improved as a whole among multiple resonators.

[0090] Furthermore, this embodiment can also be combined with the second embodiment described above. That is, it can also have a structure in which a high thermal conductivity layer 22 is provided around the excitation region 21, and a shielding electrode 57 is provided on the upper surface of the cover portion 70. In this case, the elastic wave filter device 10B can further improve heat dissipation.

[0091] (A variation of the third embodiment)

[0092] Figure 11 This is a top view showing a portion of the elastic wave filter device according to a variation of the third embodiment. Figure 11 As shown, the elastic wave filter device 10C according to the modified example of the third embodiment differs from the third embodiment described above in that a high thermal conductivity layer 22 is provided for the plurality of series arm resonators S1, S2, S3, S4, S5, S6 and the plurality of parallel arm resonators P1, P2, P3, P4, P5.

[0093] More specifically, a high thermal conductivity layer 22 is disposed around the excitation regions 21 of each of the multiple series arm resonators S1, S2, S3, S4, S5, S6 and the multiple parallel arm resonators P1, P2, P3, P4, P5. In other words, the high thermal conductivity layer 22 is configured to cover approximately the entire surface of the support member 13, except for the excitation regions 21 of each resonator.

[0094] Therefore, in this embodiment, heat dissipation can be improved in each of the multiple series arm resonators S1, S2, S3, S4, S5, S6 and the multiple parallel arm resonators P1, P2, P3, P4, P5.

[0095] In addition, Figures 9 to 11 In this process, the high thermal conductivity layer 22 is formed by a continuous arrangement pattern spanning multiple resonators, but the arrangement pattern of the high thermal conductivity layer 22 is not limited to the above-described pattern. Figures 9 to 11 The example shown can be modified as appropriate. For example, multiple high thermal conductivity layers 22 can also be provided separately for each resonator or for each of multiple resonators.

[0096] (Fourth implementation)

[0097] Figure 12 This is a cross-sectional view showing the elastic wave filter device according to the fourth embodiment. Figure 12 As shown, the elastic wave filter device 10D according to the fourth embodiment differs from the first embodiment described above in that the capacitor element 40A is a stacked type with multiple electrodes.

[0098] Capacitor element 40A includes a first electrode 47, a second electrode 48, and an insulating layer 49. The first electrode 47 is disposed opposite to the second electrode 48, sandwiching the insulating layer 49. Regarding capacitor element 40A, the first electrode 47, the insulating layer 49, and the second electrode 48 are sequentially stacked on the lower surface of the cover portion 70 opposite to the support member 13. That is, capacitor element 40A is configured as a parallel-plate capacitor. For example, dielectric materials such as Ta2O5, SiO2, and ZnO can be used as the material for the insulating layer 49.

[0099] The first electrode 47 is connected to the upper electrode 31 via the connecting wiring 45 and the inter-component connection electrode 58. In addition, the second electrode 48 is connected to the lower electrode 32 via the connecting wiring 46 and the inter-component connection electrode 59.

[0100] In this embodiment, the first electrode 47 is grounded to the cover portion 70, and the second electrode 48 is stacked on the cover portion 70, sandwiching the insulating layer 49 and the first electrode 47. That is, the contact area between the first electrode 47 and the cover portion 70 is larger than the contact area between the second electrode 48 and the cover portion 70. Therefore, the heat conduction path (first heat conduction path) from the excitation region 21 through the upper electrode 31, the inter-element connection electrode 58, the connection wiring 45, and the first electrode 47 to the cover portion 70 has higher heat dissipation than the heat conduction path (second heat conduction path) from the excitation region 21 through the lower electrode 32, the inter-element connection electrode 59, the connection wiring 46, and the second electrode 48 to the cover portion 70.

[0101] Therefore, by employing a structure in which the upper electrode 31 and the inter-element connecting electrode 58 are connected to the input terminal 61, the elastic wave filter device 10D can preferentially dissipate heat on the first heat conduction path side.

[0102] Furthermore, the capacitor element 40A has two layers of electrodes (first electrode 47 and second electrode 48), but it is not limited to this and may also be a multilayer electrode structure with three or more layers stacked. In addition, the structure of this embodiment can be combined with the structures of the second embodiment, the third embodiment, and the modified examples described above.

[0103] Furthermore, the above-described embodiments are intended to facilitate understanding of the present invention and are not intended to limit the scope of the invention. The present invention can be modified / improved without departing from its spirit, and the present invention also includes its equivalents.

[0104] In addition, this disclosure can also adopt the following structure.

[0105] (1) An elastic wave filter device, comprising:

[0106] A series arm resonator is connected between the input and output terminals;

[0107] A parallel arm resonator is connected between a node on the path connecting the input terminal and the output terminal and a ground terminal; and

[0108] A capacitor element is connected between the input terminal and the output terminal, and is connected in parallel with the series arm resonator.

[0109] (2) The elastic wave filter device according to (1), wherein,

[0110] Having multiple of the aforementioned series arm resonators,

[0111] The capacitor element is connected in parallel with one of the series arm resonators connected to the input terminal.

[0112] (3) The elastic wave filter device according to (1) or (2), wherein,

[0113] It has: a shielding electrode connected to the grounding terminal and configured opposite to the capacitor element.

[0114] (4) The elastic wave filter device according to any one of (1) to (3), wherein it has:

[0115] A piezoelectric layer having a first main surface and a second main surface opposite to the first main surface;

[0116] The support member faces the second main surface of the piezoelectric layer; and

[0117] The cover portion is opposite to the first main surface of the piezoelectric layer.

[0118] The series arm resonator and the parallel arm resonator are respectively configured to include the piezoelectric layer, an upper electrode disposed on the first main surface of the piezoelectric layer, and a lower electrode disposed on the second main surface of the piezoelectric layer.

[0119] The capacitor element is disposed on the surface of the cover that faces the first main surface of the piezoelectric layer.

[0120] (5) The elastic wave filter device according to (4), wherein it has:

[0121] The first element is connected by an electrode, electrically connecting one end of the capacitor element to one of the upper electrode and the lower electrode; and

[0122] The second element connection electrode electrically connects the other end of the capacitor element to the other of the upper electrode and the lower electrode.

[0123] (6) The elastic wave filter device according to (4) or (5), wherein,

[0124] It has: a shielding electrode disposed on the opposite side of the surface of the cover that faces the first main surface of the piezoelectric layer, and disposed in the region that overlaps with the capacitor element.

[0125] (7) The elastic wave filter device according to any one of (4) to (6), wherein,

[0126] It has: a high thermal conductivity layer disposed on the support member in the same layer as the piezoelectric layer, having a higher thermal conductivity than the piezoelectric layer.

[0127] The piezoelectric layer is at least disposed in a region overlapping with the excitation region where the lower electrode, the piezoelectric layer, and the upper electrode are stacked.

[0128] The high thermal conductivity layer is disposed in the area surrounding the excitation region.

[0129] (8) The elastic wave filter device according to (4), wherein it has:

[0130] A high thermal conductivity layer is disposed on the support member in the same layer as the piezoelectric layer, and has a higher thermal conductivity than the piezoelectric layer.

[0131] The first element connection electrode electrically connects one end of the capacitor element to the upper electrode; and

[0132] The second element is connected by an electrode, which electrically connects the other end of the capacitor element to the lower electrode.

[0133] The piezoelectric layer is at least disposed in a region overlapping with the excitation region where the lower electrode, the piezoelectric layer, and the upper electrode are stacked.

[0134] The high thermal conductivity layer is disposed in the area surrounding the excitation region and around the connecting electrode between the second elements.

[0135] (9) The elastic wave filter device according to (7) or (8), wherein it has:

[0136] A connecting member is disposed between the cover and the supporting member; and

[0137] Terminals are disposed on the surface of the cover opposite to the piezoelectric layer, and are connected to the connecting member through a through-hole in the cover.

[0138] The high thermal conductivity layer is disposed in the area overlapping with the connecting member.

[0139] (10) The elastic wave filter device according to any one of (4) to (9), wherein,

[0140] The piezoelectric layer comprises single-crystal lithium niobate or lithium tantalate.

[0141] Explanation of reference numerals in the attached figures

[0142] 10, 10A, 10B, 10C, 10D: Elastic wave filter devices;

[0143] 11: Support base plate;

[0144] 12: Insulation layer;

[0145] 13: Supporting components;

[0146] 14: Cavity;

[0147] 20: Piezoelectric layer;

[0148] 20a: 1st main surface;

[0149] 20b: Second main face;

[0150] 21: Incentive Zone;

[0151] 22: High thermal conductivity layer;

[0152] 31: Upper electrode;

[0153] 32: Lower electrode;

[0154] 40, 40A: Capacitor components;

[0155] 53: Bump;

[0156] 57: Shielding electrode;

[0157] 58, 59: Inter-component connecting electrodes;

[0158] 60: terminal;

[0159] 61: Input terminal;

[0160] 62: Output terminal;

[0161] 63: Grounding terminal;

[0162] 70: cover;

[0163] 71: Via;

[0164] 72: Connecting components;

[0165] 74, 75: Sealing parts;

[0166] S1, S2, S3, S4, S5, S6: Series arm resonators;

[0167] P1, P2, P3, P4, P5: Parallel arm resonators.

Claims

1. An elastic wave filter device, comprising: A series arm resonator is connected between the input and output terminals; A parallel arm resonator is connected between a node on the path connecting the input terminal and the output terminal and a ground terminal; as well as A capacitor element is connected between the input terminal and the output terminal, and is connected in parallel with the series arm resonator.

2. The elastic wave filter device according to claim 1, wherein, Having multiple of the aforementioned series arm resonators, The capacitor element is connected in parallel with one of the series arm resonators connected to the input terminal.

3. The elastic wave filter device according to claim 1 or claim 2, in, It has: a shielding electrode connected to the grounding terminal and configured opposite to the capacitor element.

4. The elastic wave filter device according to any one of claims 1 to 3, wherein, have: A piezoelectric layer having a first main surface and a second main surface opposite to the first main surface; A supporting member is positioned opposite the second main surface of the piezoelectric layer; as well as The cover portion is opposite to the first main surface of the piezoelectric layer. The series arm resonator and the parallel arm resonator are respectively configured to include the piezoelectric layer, an upper electrode disposed on the first main surface of the piezoelectric layer, and a lower electrode disposed on the second main surface of the piezoelectric layer. The capacitor element is disposed on the surface of the cover that faces the first main surface of the piezoelectric layer.

5. The elastic wave filter device according to claim 4, wherein, have: The first element is connected by an electrode, which electrically connects one end of the capacitor element to one of the upper electrode and the lower electrode. as well as The second element connection electrode electrically connects the other end of the capacitor element to the other of the upper electrode and the lower electrode.

6. The elastic wave filter device according to claim 4 or claim 5, wherein, It has: a shielding electrode disposed on the opposite side of the surface of the cover that faces the first main surface of the piezoelectric layer, and disposed in the region that overlaps with the capacitor element.

7. The elastic wave filter device according to any one of claims 4 to 6, wherein, It has: a high thermal conductivity layer disposed on the support member in the same layer as the piezoelectric layer, having a higher thermal conductivity than the piezoelectric layer. The piezoelectric layer is at least disposed in a region overlapping with the excitation region where the lower electrode, the piezoelectric layer, and the upper electrode are stacked. The high thermal conductivity layer is disposed in the area surrounding the excitation region.

8. The elastic wave filter device according to claim 4, wherein, have: A high thermal conductivity layer is disposed on the support member in the same layer as the piezoelectric layer, and has a higher thermal conductivity than the piezoelectric layer. The first element is connected by an electrode, which electrically connects one end of the capacitor element to the upper electrode. as well as The second element is connected by an electrode, which electrically connects the other end of the capacitor element to the lower electrode. The piezoelectric layer is at least disposed in a region overlapping with the excitation region where the lower electrode, the piezoelectric layer, and the upper electrode are stacked. The high thermal conductivity layer is disposed in the area surrounding the excitation region and around the connecting electrode between the second elements.

9. The elastic wave filter device according to claim 7 or claim 8, wherein, have: A connecting member is disposed between the cover and the supporting member; and Terminals are disposed on the surface of the cover opposite to the piezoelectric layer, and are connected to the connecting member through a through-hole in the cover. The high thermal conductivity layer is disposed in the area overlapping with the connecting member.

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

Images