Elastic wave resonator, elastic wave filter, multiplexer, high-frequency front-end circuit, and communication device

Abstract

An elastic wave resonator is an elastic wave resonator using a bulk wave of a shear vibration mode, having a piezoelectric body, an upper electrode provided on the piezoelectric body, and a lower electrode provided under the piezoelectric body, when a direction parallel to a surface of the piezoelectric body and perpendicular to a direction of the shear vibration is set as a first direction, and a direction parallel to the surface of the piezoelectric body and parallel to the direction of the shear vibration is set as a second direction, a ratio of a length (Wx1) in the first direction to a length (Wy1) in the second direction of at least one of the upper electrode and the lower electrode, that is, an aspect ratio (Wy1 / Wx1), is greater than 1.

Description

Technical Field

[0001] This invention relates to elastic wave resonators, elastic wave filters, multiplexers, high-frequency front-end circuits, and communication devices. Background Technology

[0002] Patent Document 1 describes a trapezoidal filter having parallel and series resonators. In Patent Document 1, in at least one of the parallel and series resonators, the ratio (b / a) of the length a of the short side to the length b of the long side is set to a predetermined range.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 7-154198 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In such resonators, it is necessary to improve resonator characteristics such as Q. Patent Document 1 does not consider the direction of shear vibration in the shear vibration mode.

[0008] The purpose of this invention is to provide an elastic wave resonator, elastic wave filter, multiplexer, high-frequency front-end circuit, and communication device that can improve the characteristics of the resonator.

[0009] Technical solutions for solving the problem

[0010] One proposed solution involves an elastic wave resonator that utilizes a body wave in a shear vibration mode. It comprises a piezoelectric body, an upper electrode disposed on the piezoelectric body, and a lower electrode disposed below the piezoelectric body. When a first direction is defined as parallel to the surface of the piezoelectric body and perpendicular to the direction of shear vibration, and a second direction is defined as parallel to the surface of the piezoelectric body and parallel to the direction of shear vibration, the ratio of the length (Wx1) of at least one of the upper and lower electrodes in the first direction to the length (Wy1) in the second direction, i.e., the aspect ratio (Wy1 / Wx1), is greater than 1.

[0011] One of the proposed solutions involves an elastic wave filter that incorporates the aforementioned elastic wave resonator.

[0012] One solution involves a multiplexer having multiple filters, including the aforementioned elastic wave filter, wherein one of the input terminals and one of the output terminals of each of the multiple filters are electrically connected to each other.

[0013] One of the solutions involves a high-frequency front-end circuit that includes the aforementioned elastic wave filter.

[0014] One of the solutions involves a high-frequency front-end circuit that includes the aforementioned multiplexer.

[0015] One communication device has the aforementioned high-frequency front-end circuit.

[0016] Invention Effects

[0017] The elastic wave resonator, elastic wave filter, multiplexer, high-frequency front-end circuit, and communication device according to the present invention can improve the characteristics of the resonator. Attached Figure Description

[0018] Figure 1 This is a top view showing the elastic wave resonator according to the first embodiment.

[0019] Figure 2 yes Figure 1 Sectional view II-II'.

[0020] Figure 3 This is a top view showing the structure of the upper electrode and the frame electrode.

[0021] Figure 4 This is a top view showing the structure of the upper electrode and frame electrode involved in the first modified example.

[0022] Figure 5 This is a top view showing the structure of the upper electrode and the frame electrode involved in the second modified example.

[0023] Figure 6 This is a top view showing the structure of the upper electrode and the frame electrode involved in the third modified example.

[0024] Figure 7 This is a cross-sectional view showing the structure of the upper electrode and the frame electrode involved in the fourth modified example.

[0025] Figure 8 This is a coordinate graph showing the relationship between the aspect ratio of the upper electrode and the resonant resistance of the elastic wave resonator involved in Example 1 and Comparative Example 1.

[0026] Figure 9 This is a coordinate graph showing the relationship between the aspect ratio of the upper electrode and Qmax of the elastic wave resonator involved in Example 1 and Comparative Example 1.

[0027] Figure 10 This is a coordinate graph showing the relationship between impedance and frequency of the elastic wave resonators involved in Examples 1-2 and Comparative Examples 1-1 and 1-3.

[0028] Figure 11 It is a coordinate graph showing the relationship between the real part of the impedance and the frequency of the elastic wave resonators involved in Examples 1-2 and Comparative Examples 1-1 and 1-3.

[0029] Figure 12 This is a coordinate graph showing the relationship between Q and frequency of the elastic wave resonators involved in Examples 1-2 and Comparative Examples 1-1 and 1-3.

[0030] Figure 13A This is a coordinate graph showing the relationship between the impedance and frequency of the elastic wave resonator involved in Embodiment 2-1.

[0031] Figure 13B This is a coordinate graph showing the relationship between the real part of the impedance and the frequency of the elastic wave resonator involved in Embodiment 2-1.

[0032] Figure 13C This is a coordinate graph showing the relationship between Q and frequency of the elastic wave resonator involved in Embodiment 2-1.

[0033] Figure 14A This is a coordinate graph showing the relationship between impedance and frequency of the elastic wave resonator involved in Embodiment 2-2.

[0034] Figure 14B This is a coordinate graph showing the relationship between the real part of the impedance and the frequency of the elastic wave resonator involved in Embodiment 2-2.

[0035] Figure 14C This is a coordinate graph showing the relationship between Q and frequency of the elastic wave resonator involved in Embodiment 2-2.

[0036] Figure 15A This is a coordinate graph showing the relationship between impedance and frequency of the elastic wave resonator involved in Examples 2-3.

[0037] Figure 15B This is a coordinate graph showing the relationship between the real part of the impedance and the frequency of the elastic wave resonator involved in Embodiments 2-3.

[0038] Figure 15C This is a coordinate graph showing the relationship between Q and frequency of the elastic wave resonator involved in Embodiments 2-3.

[0039] Figure 16 This is a top view showing the elastic wave resonator involved in Embodiment 3.

[0040] Figure 17 This is a coordinate graph showing the relationship between impedance and frequency of the elastic wave resonator involved in Embodiments 1-1 and 3.

[0041] Figure 18 This is a coordinate graph showing the relationship between the real part of the impedance and the frequency of the elastic wave resonator involved in Embodiments 1-1 and 3.

[0042] Figure 19This is a coordinate graph showing the relationship between Q and frequency of the elastic wave resonator involved in Embodiments 1-1 and 3.

[0043] Figure 20 This is a coordinate graph showing the relationship between the resonant resistance Zr and the ratio S / t of the elastic wave resonator involved in Embodiment 4.

[0044] Figure 21 This is a coordinate graph showing the relationship between Qmax and ratio S / t of the elastic wave resonator involved in Embodiment 4.

[0045] Figure 22 The graph shows the relationship between impedance and frequency of the elastic wave resonator involved in Example 4 according to different ratios S / t.

[0046] Figure 23 The graph shows the relationship between the real part of the impedance and the frequency of the elastic wave resonator involved in Example 4, according to different ratios S / t.

[0047] Figure 24 The graph shows the relationship between Q and frequency of the elastic wave resonator involved in Example 4 according to different ratios S / t.

[0048] Figure 25 This is a coordinate graph showing the relationship between the Euler angles and fractional bandwidth of the piezoelectric element using lithium niobate in the elastic wave resonator involved in Embodiment 5-1.

[0049] Figure 26 This is a graph showing the relationship between the Euler angles and fractional bandwidth of the piezoelectric element using lithium tantalate in the elastic wave resonator of Embodiment 5-2.

[0050] Figure 27 This is a circuit diagram showing the elastic wave filter according to the second embodiment.

[0051] Figure 28 This is a cross-sectional view schematically illustrating the structure of the elastic wave filter according to the second embodiment.

[0052] Figure 29 This is a top view schematically illustrating the structure of the resonator chip in the elastic wave filter according to the second embodiment.

[0053] Figure 30 It is shown Figure 29 A top view of the structure of the series arm resonator.

[0054] Figure 31 yes Figure 30 XXXI-XXXI' sectional view.

[0055] Figure 32This is a top view schematically showing the surface of the module substrate in the elastic wave filter according to the second embodiment.

[0056] Figure 33 This is a schematic top view showing the inner layer of the module substrate in the elastic wave filter according to the second embodiment.

[0057] Figure 34 This is a schematic top view of the back side of the module substrate in the elastic wave filter according to the second embodiment.

[0058] Figure 35 This is a top view showing the structure of the series arm resonator involved in the fifth variation.

[0059] Figure 36 This is a coordinate graph showing the filter characteristics of the elastic wave filter involved in Embodiment 6-1.

[0060] Figure 37 This is a coordinate graph showing the relationship between the aspect ratio and fractional bandwidth of the elastic wave resonator of the elastic wave filter involved in Embodiment 6.

[0061] Figure 38 This is a coordinate graph showing the filter characteristics of the elastic wave filter involved in Embodiments 6-1 and 6-2.

[0062] Figure 39 This is a diagram showing the structure of the communication device according to the third embodiment. Detailed Implementation

[0063] Hereinafter, embodiments of the present disclosure will be described in detail based on the accompanying drawings. It should be noted that the present disclosure is not limited by these embodiments. It should also be noted that the embodiments described in this disclosure are illustrative, and partial substitutions or combinations of structures are possible 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 produced by the same structure will not be mentioned repeatedly in each embodiment.

[0064] (First Implementation)

[0065] Figure 1 This is a top view showing the elastic wave resonator according to the first embodiment. Figure 2 yes Figure 1 The second-second cross-sectional view. The elastic wave resonator 10 according to the first embodiment is a resonator that utilizes the shear vibration mode of a bulk wave, namely a BAW (Bulk Acoustic Wave) element.

[0066] like Figure 1and Figure 2 As shown, the elastic wave resonator 10 has a support member 13, a piezoelectric element 20, an upper electrode 31, a lower electrode 32, a frame electrode 33, lead wires 34 and 35, and connecting electrodes 41 and 42. Figure 2 As shown, on the support member 13, the lower electrode 32 and lead wire 35, piezoelectric body 20, upper electrode 31 and lead wire 34, frame electrode 33 and connecting electrodes 41 and 42 are stacked in sequence.

[0067] In the following description, the thickness direction of the piezoelectric material 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 material 20. Furthermore, in the following description, the top view shows the arrangement when viewed from a direction perpendicular to the first main surface 20a of the piezoelectric material 20 (Z direction).

[0068] The support member 13 is disposed opposite to the second main surface 20b of the piezoelectric body 20. The support member 13 includes a support substrate 11 and an intermediate layer 12. The support substrate 11 includes silicon (Si), quartz, etc. The intermediate layer 12 is disposed between the support substrate 11 and the piezoelectric body 20. The intermediate layer 12 is formed of an insulating material such as silicon oxide. It should be noted that the support member 13 may also have a structure without the intermediate layer 12 and with the piezoelectric body 20 disposed on the support substrate 11. That is, the piezoelectric body 20 is directly bonded to the support substrate 11 or bonded to the support substrate 11 via the intermediate layer 12 (insulating layer).

[0069] A recess 14 (cavity) is formed on the surface of the support member 13 (intermediate layer 12) opposite to the second main surface 20b of the piezoelectric body 20. The recess 14 is configured to overlap with the excitation region of the resonator formed by the piezoelectric body 20, the upper electrode 31, and the lower electrode 32 when viewed from above. As a result, the energy loss of the bulk wave is reduced during excitation, resulting in good resonance characteristics.

[0070] The piezoelectric material 20 is a flat plate having a first principal surface 20a and a second principal surface 20b opposite to the first principal surface 20a. The piezoelectric material 20 is a substrate comprising a single crystal of lithium niobate (LiNbO3) or lithium tantalate (LiTaO3). The piezoelectric material 20 is not limited to these materials and may also use aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT), etc. The thickness of the piezoelectric material 20 is not particularly limited, but is preferably 1 μm or less. Alternatively, the piezoelectric material 20 may be a structure obtained by stacking multiple layers of piezoelectric materials with different crystal orientations.

[0071] The upper electrode 31 is disposed above the piezoelectric body 20 (first main surface 20a). The lower electrode 32 is disposed below the piezoelectric body 20 (second main surface 20b). Figure 1 and Figure 2 As shown, the upper electrode 31 and the lower electrode 32 overlap in the region where they overlap with the recess 14. In other words, in the region where they overlap with the recess 14, the piezoelectric element 20 is disposed between the upper electrode 31 and the lower electrode 32 in the Z direction. Thus, a bulk wave propagates 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 top view will sometimes be described as the excitation region of the resonator.

[0072] It should be noted that the names such as upper electrode 31 and lower electrode 32 are used only for defining the parts and do not limit the spatial arrangement and position of the BAW resonator. In addition, in top view, the upper electrode 31, lower electrode 32 and recess 14 are rectangular, but they are not limited to this and can also be circular or other shapes.

[0073] Lead wire 34 is disposed in the same layer as upper electrode 31 and is connected to one side of upper electrode 31 in the X direction. Lead wire 34 extends from the area overlapping with recess 14 in the X direction and is connected to connecting electrode 41, which is different from upper electrode 31. Lead wire 35 is disposed in the same layer as lower electrode 32 and is connected to the other side of lower electrode 32 in the X direction. Lead wire 35 extends from the area overlapping with recess 14 in the opposite direction to lead wire 34 and is connected to connecting electrode 42 through opening OP formed in piezoelectric body 20.

[0074] The upper electrode 31 and the lower electrode 32 are formed of conductive materials such as aluminum (Al), platinum (Pt), gold (Au), copper (Cu), molybdenum (Mo), tungsten (W), titanium (Ti), chromium (Cr), ruthenium (Ru), tantalum (Ta), and iridium (Ir), or alloys comprising at least one of these materials. The upper electrode 31 and the lower electrode 32 may also be laminated films comprising these materials. Additionally, a bonding layer such as Ti or NiCr may be provided between the upper electrode 31 and the support member 13 (intermediate layer 12). The lead-out wiring 34 is formed of the same material as the upper electrode 31. The lead-out wiring 35 is formed of the same material as the lower electrode 32. However, the lead-out wirings 34 and 35 may also be made of different materials than the upper electrode 31 and the lower electrode 32.

[0075] As described above, the elastic wave resonator 10 in this embodiment is a piezoelectric thin film resonator (FBAR). That is, a recess 14 (cavity) is formed in the portion of the support member 13 (intermediate layer 12) that overlaps with the excitation region, and the piezoelectric body 20, the upper electrode 31, and the lower electrode 32 have a diaphragm structure. However, it is not limited to this, the elastic wave resonator 10 may also be a solidly mounted resonator (SMR) in which multiple low-impedance layers and high-impedance layers are stacked instead of the recess 14 (cavity).

[0076] Next, refer to Figure 2 and Figure 3 The structure of the upper electrode 31 and the frame electrode 33 will be described. Figure 3 This is a top view showing the structure of the upper electrode and the frame electrode. Figure 3 In the diagram, arrow A indicates the direction of shear vibration of the piezoelectric element 20. In this embodiment, the direction of shear vibration of the piezoelectric element 20 indicated by arrow A is parallel to the Y direction. In other words, the X direction (first direction) is parallel to the surface (first main surface 20a) of the piezoelectric element 20 and perpendicular to the direction of shear vibration. Furthermore, the Y direction (second direction) is parallel to the surface (first main surface 20a) of the piezoelectric element 20 and parallel to the direction of shear vibration.

[0077] like Figure 2 As shown, the frame electrode 33 is grounded to the upper electrode 31 and is disposed on the upper surface of the upper electrode 31 (the side opposite to the piezoelectric body 20). For example... Figure 3 As shown, the frame electrode 33 is disposed on the outer periphery of the upper electrode 31. The frame electrode 33 is rectangular and has a first portion 33a extending along the X direction and a second portion 33b extending along the Y direction.

[0078] In this embodiment, the external shape of the upper electrode 31 is defined by the frame electrode 33. Specifically, the length Wx1 of the upper electrode 31 in the X direction is equal to the maximum length of the frame electrode 33 in the X direction. More specifically, the length Wx1 of the upper electrode 31 in the X direction is equal to the maximum length in the X direction between the outer edges of two adjacent second portions 33b of the frame electrode 33. Furthermore, the length Wy1 of the upper electrode 31 in the Y direction is equal to the maximum length in the Y direction of the frame electrode 33. More specifically, the length Wy1 of the upper electrode 31 in the Y direction is equal to the maximum length in the Y direction between the outer edges of two adjacent first portions 33a of the frame electrode 33.

[0079] The upper electrode 31 and the frame electrode 33 are rectangular in shape with their long sides along the direction of shear vibration of the piezoelectric body 20 (arrow A). That is, the length Wy1 in the Y direction of the upper electrode 31 is longer than the length Wx1 in the X direction. The ratio of the length Wx1 in the X direction to the length Wy1 in the Y direction of the upper electrode 31, i.e., the aspect ratio (Wy1 / Wx1), is greater than 1. More preferably, the aspect ratio (Wy1 / Wx1) of the upper electrode 31 is 3 or more.

[0080] In this way, the upper electrode 31 is formed to be longer along the direction of shear vibration of the piezoelectric body 20 (arrow A), thus suppressing the leakage of bulk wave energy to the outside of the excitation region. As a result, the Q of the elastic wave resonator 10 is improved.

[0081] Furthermore, the width Wx2 of the second portion 33b extending along the Y direction in the frame electrode 33 in the X direction is smaller than the width Wy2 of the first portion 33a extending along the X direction in the frame electrode 33 in the Y direction. In other words, the width Wy2 of the first portion 33a extending along a direction orthogonal to the direction of shear vibration of the piezoelectric body 20 in the frame electrode 33 is larger than the width Wx2 of the second portion 33b extending along a direction parallel to the direction of shear vibration of the piezoelectric body 20.

[0082] In this embodiment, compared to a structure with the same width formed over the entire circumference of the frame electrode 33, the area of ​​the frame electrode 33 can be reduced. This suppresses energy leakage of the bulk wave to the outside of the excitation region and reduces losses caused by boundary ring modes. It should be noted that in this embodiment, a boundary ring mode refers to the mode of the standing wave residing in the frame electrode 33 within the structure where the frame electrode 33 is positioned on the upper electrode 31. In this embodiment, by reducing the width Wx2 of the second portion 33b extending in a direction parallel to the shear vibration direction of the piezoelectric body 20, the occurrence of boundary ring modes at a predetermined frequency can be suppressed, reducing losses.

[0083] It should be noted that in this embodiment, the external shape of the upper electrode 31 has been described, but the external shape of the lower electrode 32 can also have the same structure. That is, the length Wy1 in the Y direction of the lower electrode 32 is longer than the length Wx1 in the X direction. Alternatively, the ratio of the length Wx1 in the X direction to the length Wy1 in the Y direction of the lower electrode 32, i.e., the aspect ratio (Wy1 / Wx1), is greater than 1. Furthermore, the structure of the frame electrode 33 disposed on the upper electrode 31 has been described, but it is not limited to this. The frame electrode 33 can also be disposed on the lower electrode 32, or it can be disposed on both the upper electrode 31 and the lower electrode 32. In this case, regarding... Figure 3 The description of the shape of each part of the frame electrode 33 can also be applied to the frame electrode 33 provided on the lower electrode 32.

[0084] Furthermore, the "arrangement along the outer periphery" of the frame electrode 33 includes a structure in which the frame electrode 33 is grounded to the outer periphery end of the upper electrode 31 or the lower electrode 32, and a structure in which the frame electrode 33 is arranged slightly inwardly to the outer periphery end of the upper electrode 31 or the lower electrode 32 at a predetermined interval. More specifically, for example, when the area of ​​the lower electrode 32 is smaller than that of the upper electrode 31 (see...). Figure 7 , Figure 8 In some cases, the frame electrode 33 needs to be arranged along the outer periphery of the lower electrode 32. Alternatively, if the area of ​​the lower electrode 32 is smaller than that of the upper electrode 31 and the frame electrode 33 is arranged above the upper electrode 31, the frame electrode 33 needs to be arranged along the portion of the upper electrode 31 that overlaps with the outer periphery of the lower electrode 32. Furthermore, if the shapes of the upper electrode 31 and the lower electrode 32 are different, the outer periphery of the upper electrode 31 can be considered the outer periphery of the region (excitation region) where the upper electrode 31 and the lower electrode 32 overlap. In this case, the frame electrode 33 is arranged along the outer periphery of the region (excitation region) where the upper electrode 31 and the lower electrode 32 overlap.

[0085] Furthermore, the direction of shear vibration of the piezoelectric body 20 (arrow A) is parallel to the second portion 33b of the frame electrode 33 and orthogonal to the first portion 33a. However, it is not limited to this; the direction of shear vibration of the piezoelectric body 20 (arrow A) may also have an angle of approximately ±30° relative to the extending direction of the second portion 33b of the frame electrode 33. In this case, the length Wy1 of the upper electrode 31 is defined by the maximum length of the frame electrode 33 in the direction parallel to the direction of shear vibration of the piezoelectric body 20 (Y direction). Additionally, the length Wx1 of the upper electrode 31 is defined by the maximum length of the frame electrode 33 in the direction perpendicular to the direction of shear vibration of the piezoelectric body 20 (X direction).

[0086] exist Figure 3 To make the explanation easier to understand, the case where the frame electrode 33 is rectangular, that is, the case where the upper electrode 31 has a rectangular shape, is described. However, it is not limited to this, and the shapes of the frame electrode 33 and the upper electrode 31 can also be other shapes.

[0087] Figure 4 This is a top view showing the structure of the upper electrode and frame electrode involved in the first modified example. (See attached image.) Figure 4As shown, the upper electrode 31 and frame electrode 33A involved in the first modification are elliptical in shape. More specifically, the upper electrode 31 and frame electrode 33A are elliptical in shape with their major axis along the direction of shear vibration of the piezoelectric body 20 (arrow A). That is, the length Wx1 of the upper electrode 31 is defined by the maximum length in the X direction of the elliptical shape. In addition, the length Wy1 of the upper electrode 31 is defined by the maximum length in the Y direction of the elliptical shape. Furthermore, in the first modification, the aspect ratio (Wy1 / Wx1) of the upper electrode 31 is also greater than 1.

[0088] Furthermore, in this modified example, the width Wx2 in the X direction of the portion extending along the Y direction (the portion intersecting the minor axis direction) of the frame electrode 33A is also smaller than the width Wy2 in the Y direction of the portion extending along the X direction (the portion intersecting the major axis direction) of the frame electrode 33A.

[0089] Figure 5 This is a top view showing the structure of the upper electrode and frame electrode involved in the second modified example. (See attached image.) Figure 5 As shown, in the second modification, the upper electrode 31 and the frame electrode 33B are rectangular in shape, formed by rounded corners. In other words, the first part 33Ba and the second part 33Bb of the frame electrode 33B are smoothly connected in a rounded shape. Alternatively, the upper electrode 31 and the frame electrode 33B may also be oblong in shape. The definitions of the length Wx1, Wy1, and aspect ratio (Wy1 / Wx1) of the upper electrode 31 and the width Wx2 in the X direction and the width Wy2 in the Y direction of the frame electrode 33B in the second modification are the same as those in the first embodiment described above.

[0090] Figure 6 This is a top view showing the structure of the upper electrode and frame electrode involved in the third modified example. (See attached image.) Figure 6 As shown, in the third modification, the upper electrode 31 and the frame electrode 33C are polygonal. The first portion 33Ca, the second portion 33Cb, and the third portion 33Cc of the frame electrode 33C extend at an angle relative to the direction of shear vibration of the piezoelectric body 20. In this modification, the length Wy1 of the upper electrode 31 is also the maximum length of the frame electrode 33C in the direction parallel to the direction of shear vibration of the piezoelectric body 20 (Y direction). In addition, the length Wx1 of the upper electrode 31 is the maximum length of the frame electrode 33C in the direction perpendicular to the direction of shear vibration of the piezoelectric body 20 (X direction).

[0091] In the third variation, the width Wx2 of the frame electrode 33C in the X direction is the width Wx2 of the portion of the first portion 33Ca, the second portion 33Cb, and the third portion 33Cc that extends in a direction parallel to the direction of shear vibration of the piezoelectric body 20 (e.g., the second portion 33Cb with the smallest angle to the direction of shear vibration). Furthermore, the width Wy2 of the frame electrode 33C in the Y direction is the width Wy2 of the portion of the first portion 33Ca, the second portion 33Cb, and the third portion 33Cc that extends in a direction perpendicular to the direction of shear vibration of the piezoelectric body 20 (e.g., the first portion 33Ca with the smallest angle to the direction perpendicular to the direction of shear vibration).

[0092] Figure 7 This is a cross-sectional view showing the structure of the upper electrode and frame electrode involved in the fourth modified example. For example... Figure 7 As shown, in the fourth modification, the periphery of the upper electrode 31 is disposed separately from the piezoelectric body 20 through the insulating layer 22. In this case, the length Wy1 of the upper electrode 31 is defined by the portion of the upper electrode 31 that is connected to the piezoelectric body 20 and has a frame electrode 33 (the portion stacked in the order of piezoelectric body 20, upper electrode 31, and frame electrode 33). The portion of the upper electrode 31 that is disposed separately from the piezoelectric body 20 (the portion stacked in the order of piezoelectric body 20, insulating layer 22, upper electrode 31, and frame electrode 33) is not included in the length Wy1. That is, the length Wy1 of the upper electrode 31, in the direction parallel to the direction of shear vibration of the piezoelectric body 20 (Y direction), is the length of the portion of the upper electrode 31 that is connected to the piezoelectric body 20 and has a frame electrode 33.

[0093] Furthermore, the width Wy2 in the Y direction of the frame electrode 33 is defined by the portion of the frame electrode 33 that overlaps with the area where it is in contact with the upper electrode 31 and the piezoelectric body 20 (the portion stacked in the order of piezoelectric body 20, upper electrode 31, and frame electrode 33). The portion of the frame electrode 33 that overlaps with the area where it is separated from the upper electrode 31 and the piezoelectric body 20 (the portion stacked in the order of piezoelectric body 20, insulating layer 22, upper electrode 31, and frame electrode 33) is not included in the width Wy2. That is, the width Wy2 in the Y direction of the frame electrode 33 is the length in the Y direction, parallel to the direction of shear vibration of the piezoelectric body 20, at the portion of the frame electrode 33 that overlaps with the area where it is in contact with the upper electrode 31 and the piezoelectric body 20. It should be noted that in Figure 7 The length Wy1 of the upper electrode 31 in the Y direction and the width Wy2 of the frame electrode 33 in the Y direction are described, but... Figure 7 The explanation can also be applied to the X direction.

[0094] Next, the resonator characteristics of the elastic wave resonator 10 will be explained under various conditions, such as the aspect ratio (Wy1 / Wx1) of the upper electrode 31 and the widths Wx2 and Wy2 of the frame electrode 33.

[0095] In the following embodiments and comparative examples, a single crystal of lithium niobate was used as the material for the piezoelectric body 20. The Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric body 20 are (φ, θ, ψ) = (0°, 73°, 0°).

[0096] The upper electrode 31 is stacked in the order of Ti / Pt / Ti / Al / Ti, starting from the first main surface 20a of the piezoelectric body 20. The film thicknesses of Ti / Pt / Ti / Al / Ti are 4 / 10 / 14 / 120 / 10 nm, respectively. The lower electrode 32 is stacked in the order of Ti / Pt / Ti / Al / Ti, starting from the second main surface 20b of the piezoelectric body 20. The film thicknesses of Ti / Pt / Ti / Al / Ti are 4 / 10 / 14 / 120 / 10 nm, respectively.

[0097] The frame electrode 33 is stacked on the surface of the upper electrode 31 in the order of Ti / Pt / Ti. The film thicknesses of Ti / Pt / Ti are 4 / 13 / 4 nm, respectively.

[0098] In the support member 13, the intermediate layer 12 is formed of silicon oxide (SiO2), and the support substrate 11 is formed of silicon (Si).

[0099] (Example 1)

[0100] In Example 1 and Comparative Example 1, the resonator characteristics of the elastic wave resonator 10 when the aspect ratio (Wy1 / Wx1) of the upper electrode is different will be described. Figure 8 This is a coordinate graph showing the relationship between the aspect ratio of the upper electrode and the resonant resistance of the elastic wave resonator involved in Example 1 and Comparative Example 1. Figure 9 This is a coordinate graph showing the relationship between the aspect ratio of the upper electrode and Qmax of the elastic wave resonator according to Embodiment 1 and Comparative Example 1. Table 1 shows the relationship between the aspect ratio of the upper electrode and the resonant resistance and Qmax of the elastic wave resonator according to Embodiment 1 and Comparative Example 1. It should be noted that in the following description, "Qmax" represents the maximum value of Q.

[0101] In Table 1 and Figure 8 , Figure 9Examples 1-1, 1-2, and 1-3 show the resonator characteristics when the aspect ratio (Wy1 / Wx1) of the upper electrode 31 is greater than 1 and when the aspect ratio (Wy1 / Wx1) is different. In Example 1-1, the aspect ratio (Wy1 / Wx1) is Wy1 / Wx1 = 2.0. In Example 1-2, the aspect ratio (Wy1 / Wx1) is Wy1 / Wx1 = 3.0. In Example 1-3, the aspect ratio (Wy1 / Wx1) is Wy1 / Wx1 = 4.52. Comparative Examples 1-1, 1-2, and 1-3 show the resonator characteristics when the aspect ratio (Wy1 / Wx1) of the upper electrode 31 is less than 1 and when the aspect ratio (Wy1 / Wx1) is different. In Comparative Example 1-1, the aspect ratio (Wy1 / Wx1) is Wy1 / Wx1 = 1.0. The aspect ratio (Wy1 / Wx1) of Comparative Example 1-2 is Wy1 / Wx1 = 0.66. The aspect ratio (Wy1 / Wx1) of Comparative Example 1-3 is Wy1 / Wx1 = 0.50.

[0102] Furthermore, in Examples 1-1, 1-2, 1-3 and Comparative Examples 1-1, 1-2, 1-3, the area of ​​the upper electrode 31 is fixed. That is, the impedance of the elastic wave resonator 10 involved in Examples 1-1, 1-2, 1-3 and Comparative Examples 1-1, 1-2, 1-3 is a fixed value. However, Table 1 and Figure 8 , Figure 9 This includes deviations in resonator characteristics caused by processing errors in the manufacturing process.

[0103] [Table 1]

[0104]

[0105] As shown in Table 1 and Figure 8 coordinates Figure 1 As shown, in Examples 1-1, 1-2, and 1-3, as the aspect ratio (Wy1 / Wx1) of the upper electrode 31 increases, the resonant resistance (Zr) associated with the series resistance of the elastic wave resonator 10 decreases. In Comparative Examples 1-1, 1-2, and 1-3, when the aspect ratio (Wy1 / Wx1) becomes less than 1, the resonant resistance (Zr) increases sharply.

[0106] As shown in Table 1 and Figure 9 coordinates Figure 2 As shown, in Examples 1-1, 1-2, and 1-3, Q increases as the aspect ratio (Wy1 / Wx1) of the upper electrode 31 increases. When the aspect ratio (Wy1 / Wx1) is greater than 3, Q shows a trend of saturation (the increase becomes smaller). Furthermore, in Comparative Examples 1-1, 1-2, and 1-3, Q decreases when the aspect ratio (Wy1 / Wx1) becomes 1 or less.

[0107] Figure 10This is a coordinate graph showing the relationship between impedance and frequency of the elastic wave resonators involved in Examples 1-2 and Comparative Examples 1-1 and 1-3. Figure 11 It is a coordinate graph showing the relationship between the real part of the impedance and the frequency of the elastic wave resonators involved in Examples 1-2 and Comparative Examples 1-1 and 1-3. Figure 12 This is a coordinate graph showing the relationship between Q and frequency of the elastic wave resonators involved in Examples 1-2 and Comparative Examples 1-1 and 1-3.

[0108] As mentioned above, in Figures 10 to 12 In the elastic wave resonator 10 shown in Embodiments 1-2, the aspect ratio (Wy1 / Wx1) of the upper electrode 31 is Wy1 / Wx1 = 3.0. Figures 10 to 12 In the elastic wave resonator 10 involved in Comparative Example 1-1 shown, the aspect ratio (Wy1 / Wx1) of the upper electrode 31 is Wy1 / Wx1 = 1.0. Figures 10 to 12 In the elastic wave resonator 10 involved in Comparative Examples 1-3 shown, the aspect ratio (Wy1 / Wx1) of the upper electrode 31 is Wy1 / Wx1 = 0.5.

[0109] like Figure 10 As shown, the frequency characteristics of the impedance (|Z|) of Examples 1-2 and Comparative Examples 1-1 and 1-3 all exhibit the same trend. Figure 11 As shown, the real part of the impedance in Examples 1-2 is smaller compared to Comparative Examples 1-1 and 1-3. Furthermore, as... Figure 12 As shown, Q is larger in Examples 1-2 compared to Comparative Examples 1-1 and 1-3.

[0110] Based on the above results, by making the ratio of the length Wx1 in the X direction to the length Wy1 in the Y direction of the upper electrode 31, i.e., the aspect ratio (Wy1 / Wx1), greater than 1, the resonant resistance (Zr) of the elastic wave resonator 10 can be reduced, and Q can be increased. More preferably, by setting the aspect ratio (Wy1 / Wx1) to 3 or more, the resonant resistance (Zr) can be further reduced, and Q can be made to a larger value.

[0111] (Example 2)

[0112] In Embodiment 2, the resonator characteristics of the elastic wave resonator 10 when the width Wx2 in the X direction and the width Wy2 in the Y direction of the frame electrode 33 are different will be described. Figure 13A This is a coordinate graph showing the relationship between the impedance and frequency of the elastic wave resonator involved in Embodiment 2-1. Figure 13B This is a coordinate graph showing the relationship between the real part of the impedance and the frequency of the elastic wave resonator involved in Embodiment 2-1. Figure 13C This is a coordinate graph showing the relationship between Q and frequency of the elastic wave resonator involved in Embodiment 2-1.

[0113] Figure 14A This is a coordinate graph showing the relationship between impedance and frequency of the elastic wave resonator involved in Embodiment 2-2. Figure 14B This is a coordinate graph showing the relationship between the real part of the impedance and the frequency of the elastic wave resonator involved in Embodiment 2-2. Figure 14C This is a coordinate graph showing the relationship between Q and frequency of the elastic wave resonator involved in Embodiment 2-2. Figure 15A This is a coordinate graph showing the relationship between impedance and frequency of the elastic wave resonator involved in Examples 2-3. Figure 15B This is a coordinate graph showing the relationship between the real part of the impedance and the frequency of the elastic wave resonator involved in Embodiments 2-3. Figure 15C This is a coordinate graph showing the relationship between Q and frequency of the elastic wave resonator involved in Embodiments 2-3.

[0114] Figure 13A , Figure 13B , Figure 13C , Figure 14A , Figure 14B , Figure 14C , Figure 15A , Figure 15B , Figure 15C The aspect ratio (Wy1 / Wx1) of the upper electrode 31 in Examples 2-1, 2-2, and 2-3 is Wy1 / Wx1 = 1.11. The length Wx1 of the upper electrode 31 in the X direction in Examples 2-1, 2-2, and 2-3 is Wx1 = 54.2 μm. Furthermore, the length Wy1 of the upper electrode 31 in the Y direction is Wy1 = 60.0 μm.

[0115] Figure 13A , Figure 13B , Figure 13C In the embodiment 2-1 shown, the width Wx2 of the second part 33b of the frame electrode 33 in the X direction is set to 0.7μm, and the width Wy2 of the first part 33a in the Y direction is set to 1.5μm. Figure 14A , Figure 14B , Figure 14C In the embodiment 2-2 shown, the width Wx2 of the second part 33b of the frame electrode 33 in the X direction is set to 1.5μm, and the width Wy2 of the first part 33a in the Y direction is set to 1.5μm. Figure 15A , Figure 15B , Figure 15C In the embodiments 2-3 shown, the width Wx2 of the second portion 33b in the X direction of the frame electrode 33 is set to 0 μm, and the width Wy2 of the first portion 33a in the Y direction is set to 0 μm. That is, embodiments 2-3 are structures without the frame electrode 33.

[0116] like Figure 13A , Figure 14A , Figure 15A As shown, Examples 2-1, 2-2, and 2-3 all have the same frequency characteristics of impedance.

[0117] like Figure 15B As shown, in embodiments 2-3 without frame electrodes 33, the frequency between the resonant frequency and the anti-resonant frequency (e.g.) Figure 15B The region enclosed by the single-dotted line D generates multiple unwanted responses by residing in a pattern (horizontal pattern) in the planar direction. For example... Figure 13B , Figure 14B As shown, in embodiments 2-1 and 2-2, by providing a frame electrode 33 along the outer periphery of the upper electrode 31, unwanted responses can be suppressed.

[0118] Furthermore, in Embodiment 2-2, the width Wx2 of the frame electrode 33 in the X direction is larger than that in Embodiment 2-1. Therefore, as Figure 14B As shown, in Example 2-2, on the low-frequency side of the resonant frequency (refer to...) Figure 14B Arrow C) generates ripples. This is because the second part 33b (refer to) extending along the direction of shear vibration... Figure 3 The width Wx2 in the X direction of the ) is relatively large, thereby increasing the loss at the specified frequency through the standing wave mode (Border Ring Mode (BRM)) residing in the frame electrode 33.

[0119] In embodiment 2-1, the width Wx2 in the X direction of the frame electrode 33 is smaller than the width Wy2 in the Y direction. Therefore, as... Figure 13B As indicated by arrow B, the ripple generated on the low-frequency side of the resonant frequency can be reduced. That is, in Example 2-1, by reducing the second portion 33b extending along the direction of shear vibration (refer to...) Figure 3 The width Wx2 in the X direction can suppress the loss caused by the boundary ring mode.

[0120] In addition, such as Figure 13C , Figure 14C , Figure 15C As shown, Examples 2-1 and 2-2 with frame electrode 33 have a larger Q compared to Example 2-3 without frame electrode 33.

[0121] As shown above, it is demonstrated that by making the width Wx2 in the X direction of the second portion 33b extending along the Y direction in the frame electrode 33 smaller than the width Wy2 in the Y direction of the first portion 33a extending along the X direction in the frame electrode 33, ripple on the low-frequency side of the resonant frequency can be suppressed.

[0122] (Example 3)

[0123] In Embodiment 3, the connection directions of the upper electrode 31 and the lower electrode 32 with the lead-out wirings 34 and 35 will be described. Figure 16 This is a top view showing the elastic wave resonator involved in Embodiment 3. Figure 17 This is a coordinate graph showing the relationship between impedance and frequency of the elastic wave resonator involved in Embodiments 1-1 and 3. Figure 18 This is a coordinate graph showing the relationship between the real part of the impedance and the frequency of the elastic wave resonator involved in Embodiments 1-1 and 3. Figure 19 This is a coordinate graph showing the relationship between Q and frequency of the elastic wave resonator involved in Embodiments 1-1 and 3.

[0124] like Figure 16 As shown, in the elastic wave resonator 10A according to Embodiment 3, the lead-out wiring 34A and the upper electrode 31 are in the Y direction ( Figure 16 The upper side of the middle electrode is connected, and the wiring 35A is led out to the other side of the lower electrode 32 in the Y direction. Figure 16 (The lower side of the middle) is connected. That is, in the elastic wave resonator 10A according to Embodiment 3, the lead wires 34A and 35A are connected to the short side of the resonator and extend along the direction of shear vibration.

[0125] exist Figures 17 to 19 Along with Example 3, the elastic wave resonator 10 involved in Example 1-1 is shown. In the elastic wave resonator involved in Example 1-1, as... Figure 1 and Figure 2 As described above, lead wire 34 is connected to one side of the upper electrode 31 in the X direction. Additionally, lead wire 35 is connected to the other side of the lower electrode 32 in the X direction. That is, in the elastic wave resonator 10 according to Embodiment 1-1, lead wires 34 and 35 are connected to the long side of the resonator and extend in a direction perpendicular to the direction of shear vibration.

[0126] The structure of the upper electrode 31 and the frame electrode 33 in Example 3 is the same as that in Example 1-1. That is, the aspect ratio (Wy1 / Wx1) of the upper electrode 31 in Example 3 is Wy1 / Wx1 = 2.0. The length Wx1 of the upper electrode 31 in the X direction is 40.3 μm, and the length Wy1 in the Y direction is 80.6 μm (refer to Example 1-1 in Table 1). The width Wx2 of the frame electrode 33 in the X direction is 0.7 μm, and the width Wy2 in the Y direction is 1.5 μm. Other film thickness, area, and other conditions are the same as those described in Example 1.

[0127] like Figure 17 As shown, the frequency characteristics of the impedance in Example 3 are almost identical to those of the impedance in Example 1-1.

[0128] like Figure 18 As shown, the real part of the impedance in Embodiment 3 is larger than the real part of the impedance in Embodiment 1-1. That is, in Embodiment 3, the lead wires 34A and 35A are connected to the short side of the resonator, therefore, the series resistance of the resonator is larger than that in Embodiment 1-1.

[0129] like Figure 19 As shown, Q in Example 3 is smaller than Q in Example 1-1.

[0130] Based on the above results, the lead-out wires 34 and 35 are preferably connected to at least one of the upper electrode 31 and the lower electrode 32 in the X direction (i.e., the long side of the resonator). Furthermore, the lead-out wires 34 and 35 are preferably arranged to extend from at least one of the upper electrode 31 and the lower electrode 32 in a direction perpendicular to the direction of shear vibration. As a result, the resonant resistance associated with the series resistance of the resonator decreases, and Q also increases.

[0131] (Example 4)

[0132] In Example 4, the resonator characteristics of the elastic wave resonator 10 with a fixed aspect ratio (Wy1 / Wx1) of the upper electrode 31 and different areas S of the upper electrode 31 will be described. Figure 20 This is a coordinate graph showing the relationship between the resonant resistance Zr and the ratio S / t of the elastic wave resonator involved in Embodiment 4. Figure 21 This is a coordinate graph showing the relationship between Qmax and ratio S / t of the elastic wave resonator involved in Embodiment 4. Figure 22 The graph shows the relationship between impedance and frequency of the elastic wave resonator involved in Example 4 according to different ratios S / t. Figure 23 The graph shows the relationship between the real part of the impedance and the frequency of the elastic wave resonator involved in Example 4, according to different ratios S / t. Figure 24 The graph shows the relationship between Q and frequency of the elastic wave resonator involved in Example 4 according to different ratios S / t.

[0133] Table 2 shows the relationship between the dimensions, area, and other structural features of the upper electrode and frame electrode of the elastic wave resonator involved in Embodiment 4, and the resonant resistance and Q. In Table 2, fr represents the resonant frequency of the elastic wave resonator 10, fa represents the anti-resonant frequency, Δf represents the frequency difference between the resonant frequency and the anti-resonant frequency (fa-fr), and ΔfR represents the fractional bandwidth (fa-fr) / fr of the elastic wave resonator 10.

[0134] As shown in Table 2, in Examples 4-1 to 4-6, the aspect ratio (Wy1 / Wx1) of the upper electrode 31 was fixed at Wy1 / Wx1 = 3.0, so that the area S of the upper electrode 31 was 9747 μm. 2 Up to 303.0μm 2The differences are as follows. In Examples 4-1 to 4-4, when the area of ​​the upper electrode 31 is set to S and the film thickness of the piezoelectric body 20 is set to t, the area-to-film thickness ratio S / t is 2000 μm or more. In Examples 4-5 and 4-6, the area-to-film thickness ratio S / t of the upper electrode 31 is less than 2000 μm. The stacked structure and film thickness of the upper electrode 31 and the frame electrode 33 are the same as in Example 1 above. It should be noted that in Figure 20 , 21 Tables 2 and 2 include deviations in resonator characteristics caused by processing deviations in the manufacturing process.

[0135] [Table 2]

[0136]

[0137] Figure 20 The horizontal axis of the graph shown is the ratio S / t of the area (S) of the upper electrode 31 to the film thickness (t) of the piezoelectric material 20. The vertical axis is the resonant resistance Zr, which is related to the series resistance of the resonator. Figure 21 The horizontal axis of the coordinate graph shown is the ratio S / t, and the vertical axis is Qmax.

[0138] like Figure 20 and Figure 21 As shown, when the ratio S / t is less than 2000 (Examples 4-5, 4-6), the resonant resistance Zr increases and Qmax decreases. Conversely, when the ratio S / t is greater than 2000 (Examples 4-1 to 4-4), the resonant resistance Zr decreases and Qmax increases.

[0139] like Figure 22 As shown, in Examples 4-1 to 4-4 (with a ratio S / t of 2000 or more), as the area S of the upper electrode 31 increases, i.e., as the ratio S / t increases, the impedance decreases. In Examples 4-5 and 4-6 (with a ratio S / t less than 2000), the resonant frequency fr of the elastic wave resonator 10 shifts towards the high-frequency side, and the anti-resonant frequency fa shifts towards the low-frequency side. That is, compared with Examples 4-5 and 4-6, Examples 4-1 to 4-4, with a ratio S / t of 2000 or more, have a larger frequency difference Δf and fractional bandwidth ΔfR.

[0140] like Figure 23 As shown, in Examples 4-1 to 4-4 (with a ratio S / t of 2000 or more), the real part of the impedance is smaller compared to Examples 4-5 and 4-6 (with a ratio S / t of less than 2000). Furthermore, as... Figure 24 As shown, in Examples 4-1 to 4-4 (with a ratio S / t of 2000 or more), Q is larger compared to Examples 4-5 and 4-6 (with a ratio S / t of less than 2000).

[0141] Based on the above results, it is shown that in Embodiment 4, the ratio S / t of the area S of the upper electrode 31 to the thickness t of the piezoelectric body 20 is preferably 2000 μm or more. Therefore, the elastic wave resonator 10 can reduce the resonant resistance Zr associated with the series resistance of the resonator and improve Q.

[0142] (Example 5)

[0143] In Example 5, the fractional bandwidth ΔfR and piezoelectric constant are explained when the Euler angles of the lithium niobate or lithium tantalate used in the piezoelectric body 20 are different. Figure 25 This is a graph showing the relationship between the Euler angles and fractional bandwidth of the piezoelectric element using lithium niobate in the elastic wave resonator according to Embodiment 5-1. In the elastic wave resonator 10 according to Embodiment 5-1, lithium niobate is used as the piezoelectric element 20.

[0144] Figure 25 The horizontal axis of the coordinate graph shown is the Euler angle θ of lithium niobate. For example... Figure 25 As shown, in the elastic wave resonator 10 of embodiment 5-1 utilizing body waves with shear vibration modes, the fractional bandwidth ΔfR of shear vibration (transverse wave) is larger than the fractional bandwidth ΔfR of thickness vibration (longitudinal wave). More specifically, as Figure 25 As indicated by arrow E1, the Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric element 20 are preferably in the range of (φ, θ, ψ) = (0°, 67.5 to 92°, 0°). Therefore, the elastic wave resonator 10 according to Embodiment 5-1 can achieve a wide bandwidth of 18% or more in the fractional bandwidth ΔfR.

[0145] In addition, such as Figure 25 As indicated by arrow E2, it is preferable to set the Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric body 20 to the range of (φ, θ, ψ) = (0°, 67.5~79°, 0°). Within this range, the fractional bandwidth ΔfR of the longitudinal wave (thickness direction) becomes less than 0.5%, and the elastic wave resonator 10 according to Example 5-1 can reduce unwanted waves caused by the longitudinal wave.

[0146] Figure 26 This is a graph showing the relationship between the Euler angles and fractional bandwidth of the piezoelectric element using lithium tantalate in the elastic wave resonator according to Embodiment 5-2. In the elastic wave resonator 10 according to Embodiment 5-2, lithium tantalate is used as the piezoelectric element 20.

[0147] Figure 26 The horizontal axis of the coordinate graph shown is the Euler angle θ of lithium tantalate. For example... Figure 26As shown, in the elastic wave resonator 10 of embodiment 5-2 utilizing body waves with shear vibration modes, the fractional bandwidth ΔfR of shear vibration (transverse wave) is larger than the fractional bandwidth ΔfR of thickness vibration (longitudinal wave). More specifically, as Figure 26 As indicated by arrow F1, it is preferable to set the Euler angles (φ, θ, ψ) of the lithium tantalate constituting the piezoelectric element 20 to the range of (φ, θ, ψ) = (0°, 66 to 92.5°, 0°). Therefore, the elastic wave resonator 10 according to Embodiment 5-2 can achieve a wideband fractional bandwidth ΔfR of 7% or more.

[0148] In addition, such as Figure 26 As indicated by arrow F2, it is preferable to set the Euler angles (φ, θ, ψ) of the lithium tantalate constituting the piezoelectric body 20 to the range of (φ, θ, ψ) = (0°, 67~80°, 0°). Within this range, the fractional bandwidth ΔfR of the longitudinal wave (thickness direction) becomes less than 0.5%, and the elastic wave resonator 10 according to Example 5-2 can reduce unwanted waves caused by the longitudinal wave.

[0149] In Example 5-1, when lithium niobate (transverse wave) was used as the piezoelectric element 20, the piezoelectric constant e with Euler angles (φ, θ, ψ) of (φ, θ, ψ) = (0°, 67.5~92°, 0°) was used. 34 The value is 3.2 or higher. Furthermore, in Example 5-2, when lithium tantalate (transverse wave) was used as the piezoelectric element 20, the piezoelectric constant e with Euler angles (φ, θ, ψ) of (φ, θ, ψ) = (0°, 66~92.5°, 0°) was obtained. 34 The value is 2.4 or higher. Here, unlike Examples 5-1 and 5-2, in the elastic wave resonator 10 where aluminum nitride (AlN) is used as the material for the piezoelectric element 20, the longitudinal wave is typically used as the fundamental mode, and the longitudinal piezoelectric constant e is... 33 It is approximately 1.515. Therefore, the piezoelectric constant e in the longitudinal direction is approximately 1.515 relative to the longitudinal piezoelectric constant e of the elastic wave resonator 10 using AlN with longitudinal vibration (longitudinal wave) as the fundamental mode. 33 The piezoelectric constant e in the shear direction of the elastic wave resonator 10, which uses shear vibration (transverse wave) as the fundamental mode, is obtained. 34 It is large enough, thus resulting in a wideband resonator.

[0150] The structures of the above embodiments can be appropriately combined. In addition, the specific structures and values ​​of each embodiment (e.g., the lengths Wx1 and Wy1 of the upper electrode 31, the widths Wx2 and Wy2 of the frame electrode 33, the area S of each electrode, etc.) are merely examples and are not limited thereto.

[0151] (Second Implementation)

[0152] Figure 27This is a circuit diagram showing the elastic wave filter according to the second embodiment. In the second embodiment, an elastic wave filter 50 having the elastic wave resonator 10 according to the first embodiment or the elastic wave resonator 10 according to various embodiments will be described.

[0153] like Figure 27 As shown, the elastic wave filter 50 according to the second embodiment includes a plurality of series arm resonators 61, 62, 63, 64, a plurality of parallel arm resonators 65, 66, 67, and inductors 68A and 68B. At least one of the plurality of series arm resonators 61, 62, 63, 64 and the plurality of parallel arm resonators 65, 66, 67 is any one of the elastic wave resonators 10 in the first embodiment and the elastic wave resonators 10 in each embodiment. That is, at least one of the plurality of series arm resonators 61, 62, 63, 64 is the elastic wave resonator 10 described above, and the aspect ratio (Wy1 / Wx1) of the upper electrode 31 of at least one of the plurality of series arm resonators 61, 62, 63, 64 is greater than 1. In addition, at least one of the multiple parallel arm resonators 65, 66, and 67 is the aforementioned elastic wave resonator 10, and the aspect ratio (Wy1 / Wx1) of the upper electrode 31 of at least one of the multiple parallel arm resonators 65, 66, and 67 is greater than 1.

[0154] Multiple series-arm resonators 61, 62, 63, and 64 are connected in series in the signal path between input terminal 60A and output terminal 60B. Multiple parallel-arm resonators 65, 66, and 67 are connected in parallel between the signal path between input terminal 60A and output terminal 60B and grounds 69A, 69B, and 69C. The elastic wave filter 50 according to the second embodiment is called a trapezoidal filter.

[0155] One terminal of each of the series-connected series-arm resonators 61, 62, 63, and 64 is electrically connected to input terminal 60A, and the other terminal is electrically connected to output terminal 60B. One terminal of the parallel-arm resonator 65 is electrically connected in the signal path connecting series-arm resonators 61 and 62, and the other terminal is electrically connected to ground 69A via inductor 68A. One terminal of the parallel-arm resonator 66 is electrically connected in the signal path connecting series-arm resonators 62 and 63, and the other terminal is electrically connected to ground 69B. One terminal of the parallel-arm resonator 67 is electrically connected in the signal path connecting series-arm resonators 63 and 64, and the other terminal is electrically connected to ground 69C via inductor 68B.

[0156] Inductor 68A is connected in series in the signal path connecting the parallel arm resonator 65 to ground 69A. Inductor 68B is connected in series in the signal path connecting the parallel arm resonator 67 to ground 69C.

[0157] As impedance elements, the elastic wave filter 50 may also include capacitors, among others, not limited to inductors 68A and 68B. Furthermore, the impedance elements such as inductors 68A and 68B and capacitors are not limited to structures connected to parallel arm resonators 65, 66, and 67; they may also be connected to series arm resonators 61, 62, 63, and 64. Additionally, switching elements may be connected to the impedance elements such as inductors 68A and 68B and capacitors. In this case, the frequency of the filter characteristics of the elastic wave filter 50 can be varied by switching the switching elements on and off.

[0158] Series arm resonators 61, 62, 63, and 64 are configured as multiple resonators s1, s2, s3, and s4 with series divisions, respectively. The number of divisions in each of the series arm resonators 61, 62, 63, and 64 is even. The number of divisions in each of the series arm resonators 61, 62, 63, and 64 is not limited to two; they may also be undivided or have four or more divisions. It should be noted that in the following description, "series division" refers to a structure in which multiple resonators with the same resonant frequency are connected in series. Furthermore, the description of "series division" is not limited to series arm resonators 61, 62, 63, and 64; it can also be applied to parallel arm resonators 65, 66, and 67.

[0159] Furthermore, the multiple parallel arm resonators 65, 66, and 67 respectively constitute multiple resonators p1, p2, and p3 with series division. The number of divisions for each of the multiple parallel arm resonators 65, 66, and 67 is even. The number of divisions for each of the multiple parallel arm resonators 65, 66, and 67 is not limited to two; they may also be undivided or have four or more divisions.

[0160] exist Figure 27 In the example shown, all the series arm resonators 61, 62, 63, and 64, and all the parallel arm resonators 65, 66, and 67 are series-connected. However, this is not a limitation; at least one of the series arm resonators 64 closest to the output terminal 60B can be configured to be series-connected. Alternatively, at least one of the parallel arm resonators 65, 66, and 67 closest to the output terminal 60B can be configured to be series-connected.

[0161] In this embodiment, multiple series-arm resonators 61, 62, 63, 64 and multiple parallel-arm resonators 65, 66, 67 are connected in series. Therefore, when the impedance of the resonant circuit is high, the ratio (S / t) of the area S of one of the upper electrode 31 and the lower electrode 32 to the thickness t of the piezoelectric body 20 increases, thereby improving Q. Alternatively, the power density per unit area of ​​the multiple series-arm resonators 61, 62, 63, 64 and the multiple parallel-arm resonators 65, 66, 67 decreases, thereby improving power handling performance.

[0162] Multiple series-arm resonators 61, 62, 63, 64 and multiple parallel-arm resonators 65, 66, 67 are not limited to a series-partitioned structure; they can also be parallel-partitioned. In this case, especially when the impedance of the resonant circuit is low, parallel partitioning can suppress the recess 14 (see reference). Figure 2 The area of ​​the resonator increases, which helps to suppress the decrease in mechanical strength of each resonator.

[0163] It should be noted that the structure and quantity of the multiple series arm resonators 61, 62, 63, 64 and the multiple parallel arm resonators 65, 66, 67 in the elastic wave filter 50 can be appropriately changed according to the required filter characteristics. For example, the elastic wave filter 50 can also be a structure including at least one series arm resonator and at least one parallel arm resonator.

[0164] Figure 28 This is a cross-sectional view schematically illustrating the structure of the elastic wave filter according to the second embodiment. Figure 29 This is a top view schematically illustrating the structure of the resonator chip in the elastic wave filter according to the second embodiment. Figure 30 It is shown Figure 29 A top view of the structure of the series arm resonator. Figure 31 yes Figure 30 XXXI-XXXI' sectional view. Figure 32 This is a top view schematically showing the surface of the module substrate in the elastic wave filter according to the second embodiment. Figure 33 This is a schematic top view showing the inner layer of the module substrate in the elastic wave filter according to the second embodiment. Figure 34 This is a schematic top view of the back side of the module substrate in the elastic wave filter according to the second embodiment.

[0165] like Figure 28 As shown, the elastic wave filter 50 according to the second embodiment includes a resonator chip 51, a module substrate 52, bumps 55, and sealing resin 56. The resonator chip 51 is mounted on the module substrate 52 via the bumps 55. The resonator chip 51 is configured to include... Figure 27The multiple series arm resonators 61, 62, 63, 64 and the multiple parallel arm resonators 65, 66, 67 are shown.

[0166] The module substrate 52 is a laminated substrate having multiple dielectric layers 53 and 54. For example, a printed circuit board including resin, or a ceramic substrate such as LTCC (Low Temperature Co-fired Ceramics) or HTCC (High Temperature Co-fired Ceramics) can be used for the module substrate 52. The module substrate 52 is not limited to two dielectric layers 53 and 54; it may also have three or more dielectric layers, or it may be a single-layer substrate.

[0167] like Figure 29 As shown, the resonator chip 51 has multiple series-arm resonators 61, 62, 63, 64, multiple parallel-arm resonators 65, 66, 67, and multiple terminals (input terminal 60A, output terminal 60B, and ground terminals 69A, 69B, 69C, 69D) arranged on the support member 13A. The input terminal 60A and output terminal 60B are located at opposite corners of the support member 13A in the inclined direction. The ground terminals 69A, 69B, 69C, and 69D are located at the periphery of the support member 13A. The connection relationship between the multiple series-arm resonators 61, 62, 63, 64, multiple parallel-arm resonators 65, 66, 67, and multiple terminals (input terminal 60A, output terminal 60B, and ground terminals 69A, 69B, 69C, 69D) is as follows: Figure 27 The same information is omitted here. It should be noted that the through-hole 15 is provided for etching the sacrificial layer during the formation of the recess 14A. The location, number, etc., of the through-hole 15 are not limited to... Figure 29 The example shown can be modified appropriately. Furthermore, in the above embodiment, the through hole 15 is omitted.

[0168] Figure 30 and Figure 31 A magnified view shows the structure of the series arm resonator 64 among the multiple resonators in the resonator chip 51. That is, Figure 30 and Figure 31 The structure of the series arm resonator 64, located on the output terminal 60B side, is shown among a plurality of resonators. However, the structures of the other resonators are also similar. Figure 30 and Figure 31 The series arm resonator 64 shown is the same, regarding Figure 30 and Figure 31 The description of the structure of the series arm resonator 64 can also be applied to the structure of other resonators.

[0169] like Figure 31As shown, the support member 13A includes a support substrate 11A and an intermediate layer 12A. A recess 14A (cavity) is formed on the surface of the support member 13A (intermediate layer 12A) opposite to the second main surface 20Ab of the piezoelectric body 20A. The recess 14A is shared by the two resonators s4 constituting the series arm resonator 64. In other words, one recess 14A is provided for each of the two resonators s4. It should be noted that the support member 13A, the piezoelectric body 20A, and each electrode can be made of the materials described in the first embodiment. It should also be noted that a through hole 15 is provided in the region of the piezoelectric body 20A that overlaps with the recess 14A.

[0170] like Figure 30 and Figure 31 As shown, the two resonators s4 constituting the series arm resonator 64 are respectively configured to have an upper electrode 31, a lower electrode 32, and a piezoelectric element 20A. The upper electrodes 31 of the two resonators s4 are respectively disposed on the first main surface 20Aa of the piezoelectric element 20A and are arranged separately in the X direction.

[0171] The lower electrode 32 is shared by both resonators s4 and is disposed on the second main surface 20Ab of the piezoelectric body 20A. In other words, one region of the lower electrode 32 in the X direction ( Figure 31 The right-hand portion of the piezoelectric element 20A is positioned opposite the upper electrode 31 of a resonator s4. Additionally, the region on the other side of the lower electrode 32 in the X direction ( Figure 31 The left part of the middle part is opposite to the upper electrode 31 of another resonator s4 across the piezoelectric element 20A.

[0172] Frame electrodes 33 are disposed on the outer periphery of the upper electrodes 31 of each of the two resonators s4. Lead wire 34A is connected to the upper electrode 31 of one resonator s4. Lead wire 34B is connected to the upper electrode 31 of the other resonator s4. Lead wires 34A and 34B extend in opposite directions to each other in the X direction.

[0173] Here, in the elastic wave filter 50 using BAW resonators, the spectrum of the second harmonic may sometimes be output due to the nonlinear operation of the BAW resonators. Furthermore, in the elastic wave filter 50, the second harmonic spectrum of each resonator is attenuated by the resonator on the output side before being output from the output terminal 60B. However, the second harmonic spectrum of a resonator close to the output terminal 60B (e.g., the series arm resonator 64) may be output from the output terminal 60B with almost no attenuation.

[0174] In this embodiment, the series arm resonator 64, located at least near the output terminal 60B, has two resonators s4 separated in series. Alternatively, the parallel arm resonator 67, located at least near the output terminal 60B, has two resonators p3 separated in series.

[0175] Thus, for example, when the resonator is divided into n segments in series (n is an integer), the energy density becomes n compared to the undivided resonator. 2 One-third. Therefore, in this embodiment, the nonlinear effect is reduced by 6 dB compared to the unsegmented structure.

[0176] Furthermore, since the number of segments in the series arm resonator 64 is even, the upper electrode 31 and lead-out wiring 34A of the input-side resonator s4 are formed on the same layer as the upper electrode 31 and lead-out wiring 34A of the output-side resonator s4. Therefore, compared to the case where the number of segments in the series arm resonator 64 is odd, there is no need for a via to connect the lower electrode 32 to the first main surface 20Aa side of the piezoelectric body 20A, which can suppress manufacturing costs.

[0177] In addition, Figure 30 , 31 In the diagram, arrows G1 and G2 indicate the voltage relationship of each resonator s4, arrows G3 and G4 indicate the polarization axis relationship of the piezoelectric element 20, and arrows G5 and G6 indicate the direction of displacement of the piezoelectric element 20. In this embodiment, the number of segments in the series arm resonator 64 is even; therefore, one resonator s4 (e.g., Figure 30 , Figure 31 The relationship between the voltage and polarization axis on the right side (refer to arrows G1, G3) and another resonator (e.g. Figure 30 , Figure 31 The voltage on the left side (refer to arrows G2 and G4) shows an inverse relationship with the polarization axis. Therefore, the second-order nonlinear signal is canceled out, which can reduce the second-harmonic spectrum.

[0178] The two resonators s4 of the series-connected resonator 64 are preferably of the same resonant frequency and the same impedance (the same braking capacitor). As a result, the nonlinear signals of the series-connected resonators s4 become the same magnitude, thus canceling out the second-order nonlinear signals.

[0179] like Figure 32 As shown, the module substrate 52 has multiple connection pads 57 and vias 58A. The multiple connection pads 57 are electrically connected to the input terminals 60A, output terminals 60B, and grounds 69A, 69B, 69C, and 69D of the resonator chip 51 via bumps 55. In addition, the multiple connection pads 57 are electrically connected to the inner layers and back side of the module substrate 52 vias 58A.

[0180] like Figure 33 As shown, inductors 68A and 68B are formed on the inner layer of the module substrate 52. One end of inductors 68A and 68B is connected to a pad 57 and a via 58A (see reference). Figure 32 One end is electrically connected to the surface side of the module substrate 52, and the other end is electrically connected to the back side of the module substrate 52 through a via 58B.

[0181] like Figure 34 As shown, multiple connection pads 59 are provided on the back side of the module substrate 52. The elastic wave filter 50 is mounted to the high-frequency front-end circuit 101 (see reference) via the multiple connection pads 59. Figure 39 External devices such as )

[0182] Figure 35 This is a top view showing the structure of the series arm resonator involved in the fifth variation. Figure 30 , 31 The example shown illustrates a structure in which two resonators s4, separated in series in a series arm resonator 64, form a recess 14, but is not limited to this. Figure 35 As shown, in the series arm resonator 64A involved in the fifth modification, recesses 14a and 14b are respectively provided in the two resonators s4 that are series-separated.

[0183] The two recesses 14a and 14b are arranged separately in the X direction. One resonator s4 of the series arm resonator 64A (e.g., Figure 35 The upper electrode 31 (on the right side) is configured to overlap with a recess 14a. The other resonator s4 of the series arm resonator 64A (e.g., Figure 35 The upper electrode 31 (on the left side) is arranged overlapping another recess 14b. The lower electrode 32 is arranged continuously across the two recesses 14a and 14b.

[0184] In the fifth modification, the portion of the lower electrode 32 located between the two recesses 14a and 14b is in contact with the support member 13A (intermediate layer 12A). Therefore, in the fifth modification, the heat dissipation effect from the lower electrode 32 to the support member 13A is improved, thereby enhancing the power handling performance.

[0185] (Example 6)

[0186] Figure 36 Table 3 is a coordinate graph showing the filter characteristics of the elastic wave filter according to Embodiment 6-1. Table 3 shows structural examples of each resonator of the elastic wave filter according to Embodiment 6-1.

[0187] As shown in Table 3, in the elastic wave filter 50 involved in Embodiment 6-1, the aspect ratio (Wy1 / Wx1) of the upper electrode 31 of the series arm resonators 61, 62, 63, 64 (resonators s1, s2, s3, s4) is greater than that of the upper electrode 31 of the parallel arm resonators 65, 66, 67 (resonators p1, p2, p3). The aspect ratio (Wy1 / Wx1) of the upper electrode 31 of the series arm resonators 61, 62, 63, 64 (resonators s1, s2, s3, s4) is 3.0. Furthermore, the aspect ratio (Wy1 / Wx1) of the upper electrode 31 of the parallel arm resonators 65, 66, 67 (resonators p1, p2, p3) is 2.0.

[0188] Furthermore, single crystals of lithium niobate were used as the material for piezoelectric body 20A. The Euler angles (φ, θ, ψ) of the lithium niobate constituting piezoelectric body 20A are (φ, θ, ψ) = (0°, 73°, 0°). As shown in Table 3, in the series arm resonators 61, 62, 63, 64 (resonators s1, s2, s3, s4) and the parallel arm resonators 65, 66, 67 (resonators p1, p2, p3), the ratio (S / t) of the area S of the upper electrode 31 to the thickness t of the piezoelectric body 20 is all above 2000 μm.

[0189] In the elastic wave filter 50 described in Example 6-1, the number of segments of the series arm resonators 61, 62, 63, 64 (resonators s1, s2, s3, s4) and the parallel arm resonators 65, 66, 67 (resonators p1, p2, p3) are all even.

[0190] The film thickness of the piezoelectric element 20 is fixed in the series arm resonators 61, 62, 63, 64 (resonators s1, s2, s3, s4) and the parallel arm resonators 65, 66, 67 (resonators p1, p2, p3). However, it is not limited to this, and the film thickness of each resonator can also be different according to the desired filter characteristics.

[0191] The materials of the upper electrode 31, lower electrode 32, and frame electrode 33 are shared in the series arm resonators 61, 62, 63, 64 (resonators s1, s2, s3, s4) and the parallel arm resonators 65, 66, 67 (resonators p1, p2, p3). However, the film thickness of Pt in the series arm resonators 61, 62, 63, 64 (resonators s1, s2, s3, s4) is thinner than that in the parallel arm resonators 65, 66, 67 (resonators p1, p2, p3).

[0192] [Table 3]

[0193]

[0194] like Figure 36As shown, the elastic wave filter 50 involved in Example 6-1 has a loss of less than 2.25dB in the frequency band indicated by arrow H1 (n77 frequency band: above 3300MHz and below 4200MHz).

[0195] In addition, the elastic wave filter 50 involved in Example 6-1 achieves attenuation of more than 25dB in the frequency band indicated by arrow H2 (LTE frequency band: below 2690MHz).

[0196] In addition, the elastic wave filter 50 involved in Example 6-1 achieves attenuation of more than 30dB in the frequency band indicated by arrow H3 (n79 band: 4400MHz and above and 5000MHz and below) and the frequency band indicated by arrow H4 (WiFi7 band: 5150MHz and above and 7125MHz and below).

[0197] As shown above, the elastic wave filter 50 of Embodiment 6-1 has good filter characteristics.

[0198] Next, the relationship between the aspect ratio (Wy1 / Wx1) of the upper electrode 31 of the series arm resonators 61, 62, 63, 64 (resonators s1, s2, s3, s4) and the filter characteristics of the parallel arm resonators 65, 66, 67 (resonators p1, p2, p3) in the elastic wave filter 50 will be explained.

[0199] Figure 37 This is a coordinate graph showing the relationship between the aspect ratio and fractional bandwidth of the elastic wave resonator of the elastic wave filter involved in Embodiment 6. Figure 37 The horizontal axis of the coordinate graph shown represents the aspect ratio (Wy1 / Wx1) of the upper electrode 31. Additionally, the horizontal axis of the coordinate graph represents the fractional bandwidth of the elastic wave resonator 10. It should be noted that... Figure 37 The aspect ratio (Wy1 / Wx1) and various conditions such as the size and area of ​​the upper electrode 31 of the elastic wave resonator 10 are the same as those of Examples 1-1 to 1-3 and Comparative Examples 1-1 to 1-3 shown in Table 1.

[0200] like Figure 37 As shown, the larger the aspect ratio (Wy1 / Wx1) of the upper electrode 31 of the elastic wave resonator 10, the smaller the fractional bandwidth ΔfR tends to be.

[0201] Figure 38 This is a coordinate graph showing the filter characteristics of the elastic wave filter 50 involved in Embodiments 6-1 and 6-2. Figure 38 The elastic wave filter 50 involved in Embodiment 6-1 shown is similar to the one described above. Figure 36The filter structure and characteristics are the same. The elastic wave filter 50 in Example 6-2 differs from that in Example 6-1. The aspect ratio (Wy1 / Wx1) of the upper electrode 31 of the series arm resonators 61, 62, 63, 64 (resonators s1, s2, s3, s4) is equal to that of the upper electrode 31 of the parallel arm resonators 65, 66, 67 (resonators p1, p2, p3). The aspect ratio (Wy1 / Wx1) of the upper electrode 31 of resonators s1, s2, s3, s4 and resonators p1, p2, p3 is 3.0.

[0202] like Figure 38 As shown, compared to Example 6-2, the elastic wave filter 50 involved in Example 6-1 has an attenuation approximately 3dB greater in the frequency band indicated by arrow H2 (LTE band: below 2690MHz). Furthermore, compared to Example 6-2, the elastic wave filter 50 involved in Example 6-1 has an attenuation approximately 3dB greater in the frequency band indicated by arrow H3 (n79 band: above 4400MHz and below 5000MHz).

[0203] This is because, compared with Example 6-2, Example 6-1 has a larger fractional bandwidth ΔfR of parallel arm resonators 65, 66, and 67 (i.e., a smaller aspect ratio (Wy1 / Wx1) of the upper electrode 31).

[0204] As shown above, the elastic wave filter according to Embodiment 6-1 improves filter characteristics compared to Embodiment 6-2 by making the aspect ratio (Wy1 / Wx1) of the upper electrode 31 of the series arm resonators 61, 62, 63, 64 (resonators s1, s2, s3, s4) greater than the aspect ratio (Wy1 / Wx1) of the upper electrode 31 of the parallel arm resonators 65, 66, 67 (resonators p1, p2, p3).

[0205] (Third Implementation)

[0206] Figure 39 This diagram illustrates the structure of the communication device according to the third embodiment. The communication device 100 according to the third embodiment is, for example, a portable terminal such as a mobile phone, smartphone, or tablet, or a personal computer with communication capabilities. Alternatively, the communication device 100 may also be a backhaul communication device that performs communication between base stations and communication between a base station and a core network.

[0207] like Figure 39As shown, the communication device 100 includes a high-frequency front-end circuit 101, an antenna 102, an RF-IC (Radio Frequency Integrated Circuit) 104, and a BB-IC (Baseband Integrated Circuit) 105.

[0208] The BB-IC105 forms the baseband signal processing circuit. The BB-IC105 supplies the baseband signal to the RF-IC104. The RF-IC104 performs high-frequency signal processing for transmitting and receiving signals.

[0209] The high-frequency front-end circuit 101 is connected between the antenna 102 and the RF-IC 104. In the communication device 100, high-frequency transmission signals are output from the high-frequency front-end circuit 101 to the antenna 102, and high-frequency reception signals from the antenna 102 can be received by the high-frequency front-end circuit 101.

[0210] Specifically, the high-frequency front-end circuit 101 includes a switch SW, power amplifiers 111a and 111b, matching circuits 112a and 112b, transmitting filters 113a and 113b, a multiplexer 114, matching circuits 115a and 115b, and low-noise amplifiers 116a and 116b.

[0211] When transmitting a high-frequency signal, switch SW switches to either transmit filter 113a or transmit filter 113b. The high-frequency transmit signal output from RF-IC104 is amplified by power amplifier 111a or power amplifier 111b and input to transmit filter 113a or transmit filter 113b through matching circuits 112a and 112b.

[0212] The frequency band of transmit filter 113a is, for example, n77 of the 5G NR (New Radio) standard. The frequency range of 5G NR n77 is above 3.3 GHz and below 4.2 GHz. The frequency band of transmit filter 113b is, for example, n79 of the 5G NR standard. The frequency range of 5G NR n79 is above 4.4 GHz and below 5.0 GHz.

[0213] The high-frequency transmission signal that has passed through transmission filter 113a or transmission filter 113b is supplied to antenna 102.

[0214] When receiving high-frequency signals, switch SW switches to the multiplexer 114. Multiplexer 114 includes receive filters 117a and 117b and a matching circuit 118. In multiplexer 114, the input terminals of each of the multiple receive filters 117a and 117b are electrically connected through the matching circuit 118. The frequency band of receive filter 117a is, for example, n77 of the 5G NR standard. The frequency band of receive filter 117b is, for example, n79 of the 5G NR standard.

[0215] The received signal from antenna 102 passes through matching circuit 118 and then through receive filter 117a or receive filter 117b. The high-frequency received signal that has passed through receive filter 117a or receive filter 117b is then transmitted to RF-IC 104 through matching circuits 115a, 115b and low-noise amplifier 116a or low-noise amplifier 116b.

[0216] In the communication device 100 of this embodiment, at least one of the transmitting filters 113a and 113b is an elastic wave filter 50 equipped with the aforementioned elastic wave resonator 10. Furthermore, in the multiplexer 114, at least one of the receiving filters 117a and 117b is an elastic wave filter 50 equipped with the aforementioned elastic wave resonator 10. The high-frequency front-end circuit 101 includes at least one of the transmitting filters 113a and 113b and the receiving filters 117a and 117b of the multiplexer 114. Additionally, the communication device 100 includes the high-frequency front-end circuit 101.

[0217] It should be noted that, Figure 39 The structure of the communication device 100 shown is merely schematic and can be modified accordingly. Furthermore, the frequency bands of the transmitting filters 113a and 113b and the receiving filters 117a and 117b are just one example; other communication standards can also be applied. The structure of the multiplexer 114 is also just one example and can be modified accordingly. For example, the multiple filters in the multiplexer 114 can have their output terminals electrically connected to each other depending on the mounted device.

[0218] It should be noted that the above embodiments are intended to facilitate understanding of the present invention and are not intended to limit the interpretation of the present invention. The present invention can be modified / improved without departing from its spirit, and its equivalents are also included in the present invention.

[0219] It should be noted that this disclosure can also adopt the following structure.

[0220] (1) An elastic wave resonator that utilizes a body wave of shear vibration mode, wherein,

[0221] The elastic wave resonator has:

[0222] piezoelectric elements;

[0223] An upper electrode disposed on the piezoelectric element; and

[0224] The lower electrode is disposed below the piezoelectric element.

[0225] The direction parallel to the surface of the piezoelectric element and perpendicular to the direction of shear vibration is defined as the first direction.

[0226] When the direction parallel to the surface of the piezoelectric body and parallel to the direction of the shear vibration is defined as the second direction, the ratio of the length (Wx1) of at least one of the upper electrode and the lower electrode in the first direction to the length (Wy1) in the second direction, i.e., the aspect ratio (Wy1 / Wx1), is greater than 1.

[0227] (2) According to the elastic wave resonator described in (1), where,

[0228] The aspect ratio (Wy1 / Wx1) is 3 or higher.

[0229] (3) The elastic wave resonator described in (1) or (2), wherein,

[0230] The elastic wave resonator has a frame electrode disposed on the outer periphery of at least one of the upper electrode and the lower electrode.

[0231] The width (Wx2) of the portion of the frame electrode extending along the second direction in the first direction is smaller than the width (Wy2) of the portion of the frame electrode extending along the first direction in the second direction.

[0232] (4) An elastic wave resonator described in any one of (1) to (3), wherein,

[0233] The elastic wave resonator has lead wires that are connected in the first direction to at least one of the upper electrode and the lower electrode.

[0234] (5) An elastic wave resonator according to any one of (1) to (4), wherein,

[0235] The ratio (S / t) of the area (S) of one of the upper electrode and the lower electrode to the film thickness (t) of the piezoelectric material is 2000 μm or more.

[0236] (6) An elastic wave resonator according to any one of (1) to (5), wherein,

[0237] The piezoelectric element includes lithium niobate or lithium tantalate.

[0238] (7) An elastic wave resonator according to any one of (1) to (5), wherein,

[0239] The piezoelectric element includes lithium niobate.

[0240] The Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric element are in the range of (φ, θ, ψ) = (0°, 67.5~92°, 0°).

[0241] (8) An elastic wave resonator according to any one of (1) to (5), wherein,

[0242] The piezoelectric element includes lithium niobate.

[0243] The Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric element are in the range of (φ, θ, ψ) = (0°, 67.5~79°, 0°).

[0244] (9) An elastic wave resonator according to any one of (1) to (5), wherein,

[0245] The piezoelectric element includes lithium tantalate.

[0246] The Euler angles (φ, θ, ψ) of the lithium tantalate constituting the piezoelectric element are in the range of (φ, θ, ψ) = (0°, 66 to 92.5°, 0°).

[0247] (10) An elastic wave resonator according to any one of (1) to (5), wherein,

[0248] The piezoelectric element includes lithium tantalate.

[0249] The Euler angles (φ, θ, ψ) of the lithium tantalate constituting the piezoelectric element are in the range of (φ, θ, ψ) = (0°, 67 to 80°, 0°).

[0250] (11) An elastic wave filter having an elastic wave resonator described in any one of (1) to (10).

[0251] (12) According to the elastic wave filter described in (11), where,

[0252] The elastic wave filter has a series arm resonator and a parallel arm resonator.

[0253] At least one of the series-arm resonators and the parallel-arm resonators includes the elastic wave resonator.

[0254] The aspect ratio (Wy1 / Wx1) of the series arm resonator is greater than 1.

[0255] (13) According to the elastic wave filter described in (12), where,

[0256] The parallel arm resonator includes the elastic wave resonator.

[0257] The aspect ratio (Wy1 / Wx1) of the parallel arm resonator is greater than 1.

[0258] (14) According to the elastic wave filter described in (13), where,

[0259] The aspect ratio of the series arm resonator is greater than or equal to that of the parallel arm resonator.

[0260] (15) An elastic wave filter according to any one of (11) to (14), wherein,

[0261] The elastic wave filter has an input terminal, an output terminal, multiple series-arm resonators connected between the input terminal and the output terminal, and multiple parallel-arm resonators.

[0262] The series arm resonator closest to the output terminal among the plurality of series arm resonators is configured to be segmented in series, and the number of segments of the series arm resonator is even.

[0263] (16) An elastic wave filter according to any one of (11) to (15), wherein,

[0264] The elastic wave filter has an input terminal, an output terminal, multiple series-arm resonators connected between the input terminal and the output terminal, and multiple parallel-arm resonators.

[0265] The parallel arm resonator closest to the output terminal among the plurality of parallel arm resonators is configured to be divided in series, and the number of divisions of the parallel arm resonator is even.

[0266] (17) A multiplexer having a plurality of filters, the plurality of filters including the elastic wave filters described in any one of (11) to (16),

[0267] The input and output terminals of each of the plurality of filters are electrically connected to each other.

[0268] (18) A high-frequency front-end circuit comprising an elastic wave filter described in any one of (11) to (16).

[0269] (19) A high-frequency front-end circuit having the multiplexer described in (17).

[0270] (20) A communication device having the high-frequency front-end circuit described in (18) or (19).

[0271] Explanation of reference numerals in the attached figures

[0272] 10, 10A: Elastic wave resonator;

[0273] 11, 11A: Supporting substrate;

[0274] 12, 12A: Intermediate layer;

[0275] 13, 13A: Supporting components;

[0276] 14, 14a, 14b, 14A: concave portion;

[0277] 20, 20A: Piezoelectric element;

[0278] 20a, 20Aa: First principal face;

[0279] 20b, 20Ab: Second principal face;

[0280] 31: Upper electrode;

[0281] 32: Lower electrode;

[0282] 33, 33A, 33B, 33C: Frame electrodes;

[0283] 33a, 33Ba, 33Ca: Part 1;

[0284] 33b, 33Bb, 33Cb: Part Two;

[0285] 33Cc: Part Three;

[0286] 34, 34A, 34B, 35, 35A: Outgoing wiring;

[0287] 50: Elastic wave filter;

[0288] 51: Resonator chip;

[0289] 52: Module baseboard;

[0290] 53, 54: Dielectric layer;

[0291] 55: Bump;

[0292] 56: Sealing resin;

[0293] 61, 62, 63, 64, 64A: Series arm resonators;

[0294] 65, 66, 67: Parallel arm resonators;

[0295] 100: Communication device;

[0296] 101: High-frequency front-end circuit;

[0297] Wx1, Wy1: Length;

[0298] Wx2, Wy2: Width.

Claims

1. An elastic wave resonator that utilizes a body wave with shear vibration modes, wherein, The elastic wave resonator has: piezoelectric elements; An upper electrode disposed on the piezoelectric element; and The lower electrode is disposed below the piezoelectric element. The direction parallel to the surface of the piezoelectric element and perpendicular to the direction of shear vibration is defined as the first direction. When the direction parallel to the surface of the piezoelectric element and parallel to the direction of the shear vibration is defined as the second direction... The ratio of the length Wx1 in the first direction to the length Wy1 in the second direction of at least one of the upper electrode and the lower electrode, i.e., the aspect ratio Wy1 / Wx1, is greater than 1.

2. The elastic wave resonator according to claim 1, wherein, The aspect ratio Wy1 / Wx1 is 3 or higher.

3. The elastic wave resonator according to claim 1 or 2, wherein, The elastic wave resonator has a frame electrode disposed on the outer periphery of at least one of the upper electrode and the lower electrode. The width Wx2 of the portion of the frame electrode extending along the second direction in the first direction is smaller than the width Wy2 of the portion of the frame electrode extending along the first direction in the second direction.

4. The elastic wave resonator according to any one of claims 1 to 3, wherein, The elastic wave resonator has lead wires that are connected in the first direction to at least one of the upper electrode and the lower electrode.

5. The elastic wave resonator according to any one of claims 1 to 4, wherein, The ratio S / t of the area S of one of the upper electrode and the lower electrode to the film thickness t of the piezoelectric element is greater than 2000 μm.

6. The elastic wave resonator according to any one of claims 1 to 5, wherein, The piezoelectric element includes lithium niobate or lithium tantalate.

7. The elastic wave resonator according to any one of claims 1 to 5, wherein, The piezoelectric element includes lithium niobate. The Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric element are in the range of (φ, θ, ψ) = (0°, 67.5~92°, 0°).

8. The elastic wave resonator according to any one of claims 1 to 5, wherein, The piezoelectric element includes lithium niobate. The Euler angles (φ, θ, ψ) of the lithium niobate constituting the piezoelectric element are in the range of (φ, θ, ψ) = (0°, 67.5~79°, 0°).

9. The elastic wave resonator according to any one of claims 1 to 5, wherein, The piezoelectric element includes lithium tantalate. The Euler angles (φ, θ, ψ) of the lithium tantalate constituting the piezoelectric element are in the range of (φ, θ, ψ) = (0°, 66 to 92.5°, 0°).

10. The elastic wave resonator according to any one of claims 1 to 5, wherein, The piezoelectric element includes lithium tantalate. The Euler angles (φ, θ, ψ) of the lithium tantalate constituting the piezoelectric element are in the range of (φ, θ, ψ) = (0°, 67 to 80°, 0°).

11. An elastic wave filter comprising the elastic wave resonator according to any one of claims 1 to 10.

12. The elastic wave filter according to claim 11, wherein, The elastic wave filter has a series arm resonator and a parallel arm resonator. At least one of the series-arm resonators and the parallel-arm resonators includes the elastic wave resonator. The aspect ratio Wy1 / Wx1 of the series arm resonator is greater than 1.

13. The elastic wave filter according to claim 12, wherein, The parallel arm resonator includes the elastic wave resonator. The aspect ratio Wy1 / Wx1 of the parallel arm resonator is greater than 1.

14. The elastic wave filter according to claim 13, wherein, The aspect ratio of the series arm resonator is greater than or equal to that of the parallel arm resonator.

15. The elastic wave filter according to any one of claims 11 to 14, wherein, The elastic wave filter has an input terminal, an output terminal, multiple series-arm resonators connected between the input terminal and the output terminal, and multiple parallel-arm resonators. The series arm resonator closest to the output terminal among the plurality of series arm resonators is configured to be segmented in series, and the number of segments of the series arm resonator is even.

16. The elastic wave filter according to any one of claims 11 to 15, wherein, The elastic wave filter has an input terminal, an output terminal, multiple series-arm resonators connected between the input terminal and the output terminal, and multiple parallel-arm resonators. The parallel arm resonator closest to the output terminal among the plurality of parallel arm resonators is configured to be divided in series, and the number of divisions of the parallel arm resonator is even.

17. A multiplexer having a plurality of filters, the plurality of filters comprising the elastic wave filter according to any one of claims 11 to 16. The input and output terminals of each of the plurality of filters are electrically connected to each other.

18. A high-frequency front-end circuit comprising the elastic wave filter according to any one of claims 11 to 16.

19. A high-frequency front-end circuit comprising the multiplexer of claim 17.

20. A communication device comprising the high-frequency front-end circuit as described in claim 18 or 19.

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