Elastic wave device

Abstract

An elastic wave device is provided that can suppress ripple near the upper end of the stopband. In the elastic wave device (1), an IDT electrode (7) is provided on a piezoelectric substrate (2). The IDT electrode (7) has an inclined IDT structure. When the first electrode finger (13) and the second electrode finger (14) are viewed along the elastic wave propagation direction, the overlapping intersection region has a central region and a first low-sound velocity region and a second low-sound velocity region provided on both sides of the central region. The first low-sound velocity region and the second low-sound velocity region are configured to be asymmetrical in shape with respect to the central axis extending in the length direction of the first electrode finger (13) and the second electrode finger (14).

Description

Technical Field

[0001] This invention relates to an elastic wave device having tilted IDT electrodes. Background Technology

[0002] Patent Document 1 disclosed below discloses an elastic wave device having a tilted IDT electrode and a structure for suppressing transverse modes. In this elastic wave device, in order to set a low-velocity region in the intersection region, the edge portion of the electrode finger becomes a thicker portion, which is wider than the width of the electrode finger in the central region.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: International Publication No. 2015 / 098756 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] In the elastic wave device described in Patent Document 1, the transverse mode can be suppressed because a coarse section is provided in the low sound velocity region. However, due to this electrode structure, other ripples are sometimes generated. Especially in the case of an elastic wave resonator, ripples sometimes appear near the upper end of the stopband.

[0008] The purpose of this invention is to provide an elastic wave device capable of suppressing ripple near the upper end of the stopband.

[0009] means for solving problems

[0010] The elastic wave device of the present invention comprises: a piezoelectric substrate; and an IDT electrode disposed on the piezoelectric substrate, the IDT electrode having: a first busbar; a second busbar spaced apart from the first busbar; a plurality of first electrode fingers, one end of which is connected to the first busbar; a plurality of second electrode fingers, one end of which is connected to the second busbar; a plurality of first dummy electrodes connected to the second busbar, configured such that their front ends are separated from each other by a second gap and face the first electrode fingers; and a plurality of second dummy electrodes connected to the first busbar, configured such that their front ends are separated from each other by a first gap and face the second electrode fingers; a first virtual line connecting the front ends of the plurality of second electrode fingers is inclined relative to the elastic wave propagation direction, the elastic wave propagation direction being orthogonal to the direction in which the first electrode fingers and the second electrode fingers extend; in a pair of second electrode fingers adjacent to any first electrode finger, the distance between the front end of one of the second electrode fingers and the base end of the first electrode finger is shorter than the distance between the front end of the other second electrode finger and the base end of the first electrode finger; and the first virtual line is inclined towards this distance. When the longer direction is set as an inclined direction, at least one of a convex portion and a concave portion is provided. The convex portion protrudes toward the first electrode finger side or the second electrode finger side from at least one of the following: the side of the tip of the second electrode finger on the inclined direction side, the side of the tip of the second dummy electrode on the opposite side of the inclined direction, the side of the first electrode finger on the opposite side of the inclined direction on the extension of the inclined direction from the tip of the second dummy electrode, and the side of the first electrode finger on the inclined direction side on the extension of the inclined direction from the tip of the second electrode finger. The concave portion is provided on at least one of the following: the side of the tip of the second electrode finger on the opposite side of the inclined direction, the side of the tip of the second dummy electrode, the side of the first electrode finger on the inclined direction side on the extension of the inclined direction from the tip of the second dummy electrode, and the side of the first electrode finger on the opposite side of the inclined direction on the extension of the inclined direction from the tip of the second electrode finger.

[0011] In another broad aspect of the elastic wave device of the present invention, the elastic wave device comprises: a piezoelectric substrate; and an IDT electrode disposed on the piezoelectric substrate, the IDT electrode having: a first busbar; a second busbar spaced apart from the first busbar; a plurality of first electrode fingers, one end of which is connected to the first busbar; a plurality of second electrode fingers, one end of which is connected to the second busbar; a plurality of first dummy electrodes connected to the second busbar, configured such that their front ends are spaced apart from each other by a second gap and face the first electrode fingers; and a plurality of second dummy electrodes connected to the first busbar, configured such that their front ends are spaced apart from each other by a first gap and face the second electrode fingers, connecting the front ends of the plurality of second electrode fingers. The first virtual line is inclined relative to the direction of elastic wave propagation, which is orthogonal to the direction in which the first and second electrode fingers extend. In a pair of second electrode fingers adjacent to any first electrode finger, the distance between the tip of one second electrode finger and the base of the first electrode finger is shorter than the distance between the tip of the other second electrode finger and the base of the first electrode finger. The side of the second electrode finger with the shorter distance among the sides of the first electrode finger and the side of the first virtual electrode finger opposite the first electrode finger are designated as the first side. The side opposite to the first side is designated as the second side. On the side, the distance between the tip of one of the first electrode fingers adjacent to any second electrode finger and the base of the second electrode finger is shorter than the distance between the tip of the other first electrode finger and the base of the second electrode finger. The side of the first electrode finger with the shorter distance and the side of the second dummy electrode opposite the second electrode finger are designated as the second side. The side opposite to the second side is designated as the first side. The line connecting the centers of the plurality of first gaps is designated as the second virtual line. The first gap side portion of the second dummy electrode... The region on the side is designated as the first region; the region on the second side of the first gap side portion of the second dummy electrode is designated as the second region; the region on the first side of the first gap side portion of the second electrode finger is designated as the fifth region; the region on the second side of the first gap side portion of the second electrode finger is designated as the sixth region; in adjacent first electrode fingers, in the portion closer to the first busbar than the second dummy line, the region on the first side is designated as the third region; the region on the second side is designated as the fourth region; and in the first electrode fingers, the region on the first side of the portion closer to the second busbar than the second dummy line is designated as the seventh region.The region on the second side of the portion of the second virtual line closer to the second busbar is designated as the eighth region. In the first, third, sixth, and eighth regions, the angle between the first or second side of each region and the first virtual line is an acute angle. In the second, fourth, fifth, and seventh regions, the angle between the first or second side of each region and the first virtual line is an obtuse angle. At least one of a convex portion and a concave portion is provided. The convex portion is provided in at least one of the first, third, sixth, and eighth regions, and the concave portion is provided in at least one of the second, fourth, fifth, and seventh regions.

[0012] Invention Effects

[0013] According to the present invention, an elastic wave device capable of suppressing ripple near the upper end of the stopband can be provided. Attached Figure Description

[0014] Figure 1 (a) is a top view illustrating the electrode structure of the elastic wave device according to the first embodiment of the present invention. Figure 1 (b) is an enlarged view of its main part.

[0015] Figure 2 This is a top view showing a simplified diagram illustrating the main parts of the IDT electrodes used to explain the first to eighth regions.

[0016] Figure 3 This is a partially enlarged top view used to illustrate a modified example of the first embodiment of the present invention.

[0017] Figure 4 This is a front cross-sectional view of the elastic wave device according to the first embodiment of the present invention.

[0018] Figure 5 This is a diagram showing the impedance-frequency characteristics of an elastic wave resonator, which is a conventional elastic wave device with a large amplitude.

[0019] Figure 6 It is Figure 5 The main part is shown in the enlarged diagram.

[0020] Figure 7 This is a schematic top view used to illustrate the displacement distribution in conventional elastic wave devices.

[0021] Figure 8 This is an enlarged top view used to illustrate the relationship between displacement distribution and the shape of electrode fingers in conventional elastic wave devices.

[0022] Figure 9 This is a schematic top view illustrating the main parts of the elastic wave device according to the first embodiment of the present invention.

[0023] Figure 10 This is a graph showing the return loss characteristics of Example 1 and Comparative Example 1.

[0024] Figure 11 This is a front sectional view illustrating the elastic wave device of the second embodiment of the present invention.

[0025] Figure 12 This is a front sectional view illustrating the elastic wave device of the third embodiment of the present invention. Detailed Implementation

[0026] Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings, thereby making the present invention clear.

[0027] It should be noted that the embodiments described in this specification are illustrative, and it is indicated in advance that partial substitutions or combinations of structures can be made between different embodiments.

[0028] Figure 1 (a) is a top view showing a simplified diagram of the electrode structure of the elastic wave device according to the first embodiment of the present invention. Figure 1 (b) is an enlarged view of its main parts. Additionally, Figure 4 This is a front cross-sectional view of the elastic wave device according to the first embodiment.

[0029] like Figure 4 As shown, the elastic wave device 1 has a piezoelectric substrate 2. IDT electrodes 7 and reflectors 8 and 9 are disposed on the piezoelectric substrate 2. Thus, a single-port elastic wave resonator is constructed.

[0030] The piezoelectric substrate 2 has a structure in which a support substrate 3, a high-velocity material layer 4, a low-velocity material layer 5, and a piezoelectric film 6 are sequentially stacked. The support substrate 3 includes suitable semiconductors or dielectrics such as Si and bauxite.

[0031] The piezoelectric film 6 includes piezoelectric single crystals such as LiTaO3. The hypersonic material layer 4 includes a hypersonic material, in which the speed of sound of bulk waves propagating is higher than the speed of sound of elastic waves propagating in the piezoelectric film 6. As such a hypersonic material, various materials can be used, such as alumina, silicon carbide, silicon nitride, silicon oxynitride, silicon, sapphire, lithium tantalate, lithium niobate, quartz, bauxite, zirconium oxide, cordierite, mullite, block talc, forsterite, magnesium oxide, DLC (diamond-like carbon) film or diamond, media mainly composed of the above materials, and media mainly composed of mixtures of the above materials.

[0032] The low-velocity material layer 5 includes a low-velocity material, wherein the velocity of sound waves propagating in this low-velocity material is lower than the velocity of sound waves propagating in the piezoelectric film 6. Various materials can be used as such a low-velocity material, including silicon oxide, glass, silicon oxynitride, tantalum oxide, compounds obtained by adding fluorine, carbon, boron, hydrogen, or silanol groups to silicon oxide, and media with the above materials as the main component.

[0033] Since the piezoelectric substrate 2 is constructed as described above, the elastic wave excited by the piezoelectric film 6 can be effectively contained within the piezoelectric film 6. It should be noted that the support substrate 3 can also be a hypersonic support substrate made of the same material as the hypersonic material layer 4. In this case, the piezoelectric substrate 2 may not have the hypersonic material layer 4. That is, the layer structure of the piezoelectric substrate 2 can also be a structure in which a hypersonic support substrate, a low-velocity material layer, and a piezoelectric film are sequentially stacked.

[0034] The IDT electrode 7 and reflectors 8 and 9 comprise suitable metals or alloys. Alternatively, the IDT electrode 7 and reflectors 8 and 9 may also be composed of a stack of multiple metal films.

[0035] like Figure 1 of (a), Figure 1 As shown in (b), the IDT electrode 7 has a so-called tilted configuration. The IDT electrode 7 has a first busbar 11 and a second busbar 12. The first busbar 11 and the second busbar 12 are in... Figure 1 The middle section tilts downwards from left to right relative to the horizontal direction as shown in the attached diagram. The first busbar 11 is parallel to the second busbar 12.

[0036] Multiple first electrode fingers 13 are connected to the first busbar 11. Multiple second electrode fingers 14 are connected to the second busbar 12. The multiple first electrode fingers 13 and multiple second electrode fingers 14 are arranged to be inserted alternately. On the other hand, multiple second dummy electrodes 16 are connected to the first busbar 11. Multiple first dummy electrodes 15 are connected to the second busbar 12. The front ends of the second dummy electrodes 16 and the second electrode fingers 14 are opposite each other with a first gap G1 between them. Similarly, the front ends of the first electrode fingers 13 and the first dummy electrodes 15 are opposite each other with a second gap G2 between them.

[0037] like Figure 2As shown, the elastic wave propagation direction D is orthogonal to the directions in which the first electrode finger 13 and the second electrode finger 14 extend. The first virtual line A is inclined relative to the elastic wave propagation direction D. The first virtual line A is a virtual straight line formed by connecting the front ends of multiple second electrode fingers 14 to each other. It should be noted that the virtual straight line formed by connecting the centers of multiple first gaps G1 is designated as the second virtual line B. In addition, on the second gap G2 side, the virtual line formed by connecting the front ends of multiple first electrode fingers 13 is the third virtual line A1. The virtual line formed by connecting the centers of multiple second gaps G2 is designated as the fourth virtual line B1.

[0038] The first virtual line A and the third virtual line A1 mentioned above are inclined relative to the direction of elastic wave propagation D.

[0039] like Figure 1 As shown in (a), when viewed along the elastic wave propagation direction D, the area where the first electrode finger 13 and the second electrode finger 14 overlap is the intersection region K. The intersection region K has a central region C, and a first low-sound velocity region L1 and a second low-sound velocity region L2 disposed outside the extending direction of the first electrode finger 13 and the second electrode finger 14 in the central region C. Here, the protrusions 17, which will be described later, are provided in the first low-sound velocity region L1 and the second low-sound velocity region L2, thereby achieving low-sound velocity.

[0040] It should be noted that in the cross region K, other regions may be further set outside the extension direction of the first electrode finger 13 and the second electrode finger 14 of the first low-sound speed region L1 and the second low-sound speed region L2.

[0041] In the elastic wave device 1, a high-speed region is further provided outside the first low-speed region L1 and the second low-speed region L2, thereby suppressing the ripple generated by the transverse mode. This transverse mode suppression structure is the same as that of the elastic wave device described in Patent Document 1.

[0042] like Figure 1 As shown in (a), reflectors 8 and 9 have a configuration that short-circuits the two ends of multiple electrodes via busbars. In reflectors 8 and 9, the busbars on both sides are also inclined in the same way as the first busbar 11 and the second busbar 12.

[0043] Such an inclined IDT electrode is also shown in Patent Document 1. Furthermore, in the elastic wave device described in Patent Document 1, a coarse section is provided at the front ends of the first and second electrode fingers to suppress transverse modes. However, the inventors of this application have discovered that by providing such a coarse section, ripples are generated near the upper end of the stopband.

[0044] In the elastic wave device 1, ripples near the upper end of the aforementioned stopband can be suppressed. This is because protrusions 17 are provided on the first electrode finger 13, the second electrode finger 14, the first dummy electrode 15, and the second dummy electrode 16. This will be explained in more detail.

[0045] like Figure 1 As shown in (b), the first electrode finger 13 and the second electrode finger 14 have first sides 13a, 14a and second sides 13b, 14b, respectively. The first dummy electrode 15 and the second dummy electrode 16 also have first sides 15a, 16a and second sides 15b, 16b.

[0046] Compare the first bus bar 11 to Figure 2 The direction of the horizontal inclination downwards is defined as the tilt direction. Thus, the IDT electrode 7 has a tilted structure. Therefore, the distance between the tip of one of the second electrode fingers 14 adjacent to any first electrode finger 13 and the base of the first electrode finger 13 is shorter than the distance between the tip of the other second electrode finger 14 and its base. In this embodiment, the side of the second electrode finger 14 with the shorter distance among the sides of the first electrode finger 13 is the first side 13a. The side of the second electrode finger 14 with the shorter distance among the sides of the first dummy electrode 15 opposite to the first electrode finger 13 is the first side 15a. The sides opposite to the first sides 13a and 15a are the second sides 13b and 15b. Similarly, the distance between the tip of one of the first electrode fingers 13 adjacent to any second electrode finger 14 and the base of the second electrode finger 14 is shorter than the distance between the tip of the other first electrode finger 13 and its base. In this embodiment, the side of the first electrode finger 13, which is the shorter of the two sides of the second electrode finger 14, is the second side 14b. The side of the first electrode finger 13, which is the shorter of the two sides of the second dummy electrode 16 opposite to the second electrode finger 14, is the second side 16b. The sides opposite to the second sides 14b and 16b are the first sides 14a and 16a.

[0047] like Figure 2As shown, the region on the first side 16a of the portion of the second dummy electrode 16 facing the first gap G1 is designated as the first region R1, and the region on the second side 16b is designated as the second region R2. The region on the first side 14a of the second electrode finger 14 facing the first gap G1 is designated as the fifth region R5, and the region on the second side 14b is designated as the sixth region R6. In the portion of the first electrode finger 13 adjacent to the second dummy electrode 16 in the aforementioned inclined direction that is closer to the first busbar 11 than the second dummy line B, the region on the first side 13a is designated as the third region R3, and the region on the second side 13b is designated as the fourth region R4. In the first electrode finger 13, the region on the first side 13a of the portion closer to the second busbar 12 than the second dummy line B is designated as the seventh region R7, and the region on the second side 13b is designated as the eighth region R8.

[0048] In the first region R1 and the third region R3, the angle F2 formed by the first side 16a and 13a of each region and the first virtual line A is an acute angle. Similarly, in the sixth region R6 and the eighth region R8, the angle F2 formed by the second side 14b and 13b of each region and the first virtual line A is an acute angle.

[0049] On the other hand, in the second region R2 and the fourth region R4, the angle F1 formed by the second sides 16b and 13b and the first virtual line A is an obtuse angle. Similarly, in the fifth region R5 and the seventh region R7, the angle F1 formed by the first sides 14a and 13a and the first virtual line A is also an obtuse angle.

[0050] Here, the angles formed by the first side or the second side of each of the regions R1 to R8 and the first virtual line A refer to the intersection angles at portions located within the regions R1 to R8. Furthermore, the angles in each region refer to the intersection angles between the portion of the first side or the second side of each region and the region side of the first virtual line A.

[0051] In this invention, at least one of the following is provided: at least one protrusion provided in at least one of the first region R1, the third region R3, the sixth region R6 and the eighth region R8, and at least one recess provided in at least one of the second region R2, the fourth region R4, the fifth region R5 and the seventh region R7. In other words, at least one of a protrusion and a recess is provided. The protrusion protrudes towards either the first or second electrode finger from at least one of the following sides: the side of the second electrode finger on the side facing the inclined direction of the tip of the second electrode finger, the side of the first electrode finger on the side facing the inclined direction of the tip of the second dummy electrode extending in the inclined direction from the tip of the second dummy electrode, and the side of the first electrode finger on the side facing the inclined direction of the tip of the second electrode finger extending in the inclined direction of the tip of the second electrode finger. The recess is provided on at least one of the following sides: the side of the second electrode finger on the side facing the inclined direction of the tip of the second electrode finger, the side of the second dummy electrode on the side facing the inclined direction of the tip of the second dummy electrode, the side of the first electrode finger on the side facing the inclined direction of the tip of the second dummy electrode extending in the inclined direction of the tip of the second electrode finger, and the side of the first electrode finger on the side facing the inclined direction of the tip of the second electrode finger extending in the inclined direction of the tip of the second electrode finger. This allows for the suppression of ripple near the upper end of the stopband.

[0052] In this embodiment, the aforementioned concave or convex portion is, for example... Figure 1 (a) and Figure 1 As shown in (b), a protrusion 17 is provided. More specifically, on the first side 16a of the second dummy electrode 16, a protrusion 17 protruding toward the side opposite to the first electrode finger 13 is provided in the first region R1. That is, a protrusion 17 is provided in the first region R1. Similarly, a protrusion 17 is also provided in the sixth region R6.

[0053] In conventional elastic wave devices, the coarse section is located at the front end of the electrode finger. As a result, ripples appear near the upper end of the stopband. Figure 5 This is a graph showing the impedance-frequency characteristics of an elastic wave resonator in a conventional elastic wave device. Figure 6 It is a diagram showing a portion of it magnified.

[0054] Depend on Figure 5 It is known that a large ripple appears in the vicinity of 5780MHz to 5920MHz, which is higher than the anti-resonant frequency. Regarding this ripple, the inventors of this application believe it is caused by the aforementioned coarse portion being symmetrically disposed at the front end of the electrode finger relative to the center of the electrode finger. Therefore, in this invention, as described above, protrusions and / or recesses are provided in the first region R1 to the eighth region R8, thereby suppressing the ripple. This will be explained in more detail below.

[0055] In conventional elastic wave devices, a low-velocity region is created by placing the thicker portion at the tip of the electrode finger. (See reference...) Figure 7 The displacement distribution under this condition is explained. Figure 7 This is a schematic top view showing an enlarged portion of the electrode structure of a conventional elastic wave device 100. Here, a thickened portion 102a is provided at the front end of the second electrode finger 102. In addition, a thickened portion 104a is also provided at the front end of the second dummy electrode 104.

[0056] The coarse portion 102a and the coarse portion 104a are positioned opposite each other across a first gap G1. In this case, when the first electrode finger 101 connected to the first busbar becomes the hot side, since the IDT electrode has an inclined structure, the region with a larger displacement on the positive potential side is shown as region H2, marked with a shaded line. On the other hand, the regions with a larger displacement on the negative potential side are shown as regions H1 and H3, marked with shaded lines.

[0057] Depend on Figure 7 As can be seen, due to the tilted structure of the IDT electrode, the portion with larger displacement is tilted relative to the extending direction of the first electrode finger 101 and the second electrode finger 102. That is, as... Figure 8 As shown in a further magnified view, region H2, illustrated in a simplified diagram, is inclined relative to the extension direction of the second electrode finger 102 and the second dummy electrode 104.

[0058] When the aforementioned coarse portions 102a and 104a are arranged symmetrically with respect to the central axis of the length direction of the second electrode finger 102 or the second dummy electrode 104, it is assumed that the aforementioned ripples occur due to the offset of the tilt angle with respect to the aforementioned regions H1 to H3.

[0059] In contrast, such as Figure 9 As shown, in this embodiment, protrusions 17 are provided in the first region R1 and the sixth region R6, for example, to cooperate with the tilt of the regions H1 to H3. Therefore, ripple near the upper end of the stopband can be suppressed. This will be explained based on specific experimental examples.

[0060] Based on the conventional elastic wave device described above, the elastic wave device of Comparative Example 1 was constructed. In contrast, an elastic wave device of Embodiment 1 was manufactured that was constructed in the same manner as Comparative Example 1, except that the protrusion 17 was provided instead of the thick portion. The design parameters of the elastic wave device of Embodiment 1 are as follows.

[0061] Layer structure of piezoelectric substrate, materials of each layer, and thickness of each layer: piezoelectric film / low-velocity material layer / high-velocity support substrate, LiTaO3 / SiO2 / Si, 0.350μm / 0.450μm / 250μm.

[0062] Material of IDT electrode 7 and reflectors 8 and 9: Al. Thickness = 60 nm.

[0063] The wavelength λ = 0.7 μm is determined by the distance between the electrode fingers of IDT electrode 7.

[0064] The number of electrode fingers: a pair of models is set to infinite periodicity based on the boundary conditions.

[0065] The angle between the first virtual line A and the direction of elastic wave propagation D is 5°.

[0066] The dimension of the electrode fingers extending in the first gap G1 and the second gap G2 is 0.28 μm.

[0067] The protrusion amount, measured from the first or second side of the protrusion 17, is 0.07 μm.

[0068] The dimension of the electrode finger of protrusion 17 in the extension direction is 0.2 μm.

[0069] Figure 10 The return loss characteristics of the elastic wave devices of Comparative Example 1 and Embodiment 1 are shown. It should be noted that, in Figure 10 In the diagram, solid lines show the results of Example 1, and dashed lines show the results of Comparative Example 1.

[0070] Depend on Figure 10 As can be seen, in Comparative Example 1, multiple large ripples appeared in the range of 5780MHz to 5900MHz, which is higher than the anti-resonant frequency. This is ripple near the upper end of the stopband. In contrast, according to Example 1, such ripples can be effectively suppressed. Therefore, according to Example 1, by providing the aforementioned protrusion 17 and configuring the thick portions at the front ends of the second electrode finger 14 and the second dummy electrode 16 to be asymmetrical, the aforementioned ripples near the upper end of the stopband can be effectively suppressed.

[0071] It should be noted that, by Figure 9 As can be seen from regions H1 to H3, it is desirable to replace the protrusion 17 with concave portions in the second region R2, the fifth region R5, the fourth region R4, and the seventh region R7. Therefore, as Figure 3 As shown in the modified example, it is desirable to provide a recess 17A on the first side 14a of the front end of the second electrode finger 14, and also to provide a recess 17A on the second side 16b of the second dummy electrode 16. It should be noted that in the first embodiment, the front end of the electrode finger including the protrusion 17 is rectangular. On the other hand, as in this modified example, the front end of the electrode finger including the protrusion 17 can also be parallelogram-shaped.

[0072] However, in this invention, it is not necessary to provide the protrusions 17 or recesses 17A in all of the first regions R1 to the eighth regions R8. As described above, a protrusion may be provided in at least one location in the region where a protrusion is desired, or a recess may be provided in at least one location in the region where a recess 17A is desired. Alternatively, it is sufficient to provide the protrusions 17 or recesses 17A in at least one of the first regions R1 to the eighth regions R8.

[0073] Furthermore, regarding the first gap G1 side, the first region R1 to the eighth region R8 are shown, but on the second gap G2 side, the first region R1 to the eighth region R8 are also defined similarly, and a protrusion 17 or a recess 17A is provided. That is, as... Figure 2 As shown, the fourth virtual line B1 connecting the centers of the second gap G2 and the third virtual line A1 connecting the front ends of the multiple first electrode fingers 13 are used as references to define the first region R1 to the eighth region R8. Preferably, at least one of the above-mentioned protrusions 17 or recesses 17A is provided in these first regions R1 to the eighth region R8. In other words, preferably, at least one of a recess and a convex portion is provided. The recess is provided on at least one side of the first electrode finger's tip on the side facing the inclined direction, the first dummy electrode's tip on the side facing the opposite direction, the second electrode finger's side facing the opposite direction on the extension from the first dummy electrode's tip in the opposite direction, and the side of the second electrode finger's tip facing the inclined direction on the extension from the first electrode finger's tip in the opposite direction. The convex portion protrudes toward the first electrode finger side or the second electrode finger side from at least one side of the first electrode finger's tip facing the opposite direction, the first dummy electrode's tip on the side facing the inclined direction, the second electrode finger's side facing the inclined direction on the extension from the first dummy electrode's tip in the opposite direction, and the side of the second electrode finger's side facing the opposite direction on the extension from the first electrode finger's tip in the opposite direction.

[0074] It should be noted that, on the second gap G2 side, in the first region R1, the third region R3, the sixth region R6, and the eighth region R8, the angles formed by the first side edges 13a, 14a or the second side edges 14b, 15b and the third virtual line A1 are acute angles; in the second region R2, the fourth region R4, the fifth region R5, and the seventh region R7, the angles formed by the second side edges 13b, 14b or the first side edges 14a, 15a and the third virtual line A1 are obtuse angles. Therefore, a protrusion is provided in at least one of the first region R1, the third region R3, the sixth region R6, and the eighth region R8, and a recess is provided in at least one of the second region R2, the fourth region R4, the fifth region R5, and the seventh region R7.

[0075] Furthermore, preferably, such as Figure 3 As shown in the modified example, in the second region R2 and the third region R3 opposite each other in the elastic wave propagation direction, if the second region R2 is provided with a recess 17A, it is preferable to provide a protrusion 17 in the third region R3. This increases the distance between the second dummy electrode 16 and the first electrode finger 13 along the elastic wave propagation direction. This improves surge withstand capability. Therefore, it is preferable that at least one of the portions opposite the second region R2 and the third region R3, and the portions opposite the sixth region R6 and the seventh region R7, is provided with a recess and a protrusion. More specifically, the IDT electrode preferably has at least one of the following structures: a recess in the second region R2 and a protrusion in the third region R3, and a protrusion in the sixth region R6 and a recess in the seventh region R7.

[0076] Figure 11 This is a front cross-sectional view illustrating the elastic wave device according to the second embodiment of the present invention. In the elastic wave device 31, the high-velocity material layer 4a also serves as a support substrate. That is, the high-velocity material layer 4a is a high-velocity support substrate comprising high-velocity material. In this case, it is possible to omit... Figure 4 The support substrate 3 shown. A piezoelectric substrate 2a can also be used.

[0077] In addition, Figure 4 or Figure 11 In this case, the low-velocity material layer 5 can also be omitted.

[0078] in addition, Figure 12 This is a front cross-sectional view illustrating the elastic wave device according to the third embodiment of the present invention. In the elastic wave device 41, the piezoelectric substrate 2 is a piezoelectric substrate comprising a single plate of a piezoelectric single crystal such as LiNbO3. In the present invention, such a single-plate piezoelectric substrate can also be used to construct the piezoelectric substrate 2.

[0079] Explanation of reference numerals in the attached figures

[0080] 1…elastic wave device;

[0081] 2, 2a… Piezoelectric substrate;

[0082] 3...support base plate;

[0083] 4, 4a…High-speed acoustic material layer;

[0084] 5…low-velocity material layer;

[0085] 6…piezoelectric film;

[0086] 7…IDT electrode;

[0087] 8, 9... reflectors;

[0088] 11, 12… First busbar, Second busbar;

[0089] 13…First electrode finger;

[0090] 13a, 13b... First side, second side;

[0091] 14…Second electrode finger;

[0092] 14a, 14b... First side, second side;

[0093] 15…First dummy electrode;

[0094] 15a, 15b... First side, second side;

[0095] 16…Second dummy electrode;

[0096] 16a, 16b... First side, second side;

[0097] 17...convex part;

[0098] 17A...concave;

[0099] 31…elastic wave device;

[0100] 41…elastic wave device;

[0101] 100…elastic wave device;

[0102] 101, 102… First electrode finger, second electrode finger;

[0103] 102a…thick section;

[0104] 104…Second dummy electrode;

[0105] 104a…Rough section.

Claims

1. An elastic wave device, comprising: piezoelectric substrates; and IDT electrodes are disposed on the piezoelectric substrate. The IDT electrode has: First busbar; The second busbar is spaced apart from the first busbar; Multiple first electrode fingers, one end of which is connected to the first bus bar; Multiple second electrode fingers, one end of which is connected to the second bus bar; Multiple first dummy electrodes, connected to the second busbar, are configured such that their front ends are positioned opposite the first electrodes, separated by a second gap; and Multiple second dummy electrodes are connected to the first busbar, and their front ends are positioned opposite each other with a first gap between them, pointing towards the second electrodes. The first virtual line connecting the tips of multiple second electrode fingers is inclined relative to the direction of elastic wave propagation, which is orthogonal to the direction in which the first and second electrode fingers extend. In a pair of second electrode fingers adjacent to any first electrode finger, the distance between the tip of one second electrode finger and the base of the first electrode finger is shorter than the distance between the tip of the other second electrode finger and the base of the first electrode finger. When the direction of the first virtual line towards the longer distance is defined as the inclined direction... It is provided with at least one of a convex part and a concave part. The protrusion protrudes toward either the first electrode finger or the second electrode finger from at least one of the following: the side of the second electrode finger on the side facing the inclined direction at the tip of the second electrode finger; the side of the first electrode finger on the side facing the inclined direction on the extension of the inclined direction from the tip of the second dummy electrode; and the side of the first electrode finger on the side facing the inclined direction on the extension of the inclined direction from the tip of the second electrode finger. The recess is provided on at least one of the following: the side opposite to the inclined direction of the front end of the second electrode finger; the side of the front end of the second dummy electrode on the inclined direction; the side of the first electrode finger on the inclined direction located on the extension of the inclined direction from the front end of the second dummy electrode; and the side of the first electrode finger on the opposite to the inclined direction of the inclined direction located on the extension of the inclined direction from the front end of the second electrode finger.

2. The elastic wave device according to claim 1, wherein, The third virtual line connecting the tips of multiple first electrode fingers is inclined relative to the direction of elastic wave propagation. In a pair of first electrode fingers adjacent to any second electrode finger, the distance between the tip of one first electrode finger and the base of the second electrode finger is shorter than the distance between the tip of the other first electrode finger and the base of the second electrode finger. The side of the first electrode finger with the shorter distance, and the side of the second virtual electrode finger opposite the second electrode finger, with the shorter distance, are designated as the first side. The side opposite to the first side is designated as the second side. If the distance between the tip of one of the second electrode fingers adjacent to any first electrode finger and the base of the first electrode finger is shorter than the distance between the tip of the other second electrode finger and the base of the first electrode finger, then the side of the second electrode finger with the shorter distance and the side of the first dummy electrode opposite the first electrode finger are designated as the second side. The side opposite to the second side is designated as the first side. The line connecting the centers of the multiple second gaps is designated as the fourth virtual line. The device is provided with at least one of the following: a recess and a protrusion. The recess is located on at least one side of the first electrode finger's tip on the side facing the inclined direction, on the side of the first dummy electrode's tip facing the opposite direction, on the side of the second electrode finger located on the side facing the opposite direction, extending from the first dummy electrode in the opposite direction, and on the side of the second electrode finger located on the side facing the inclined direction, extending from the first electrode finger's tip in the opposite direction. The protrusion protrudes toward either the first electrode finger or the second electrode finger from at least one of the following: the side of the first electrode finger's tip facing the opposite direction, the side of the first dummy electrode's tip facing the inclined direction, the side of the second electrode finger located on the side facing the opposite direction, extending from the first dummy electrode's tip in the opposite direction, and the side of the second electrode finger located on the side facing the opposite direction, extending from the first electrode finger's tip in the opposite direction.

3. The elastic wave device according to claim 2, wherein, The third virtual line connecting the tips of multiple first electrode fingers is inclined relative to the direction of elastic wave propagation. In a pair of first electrode fingers adjacent to any second electrode finger, the distance between the tip of one first electrode finger and the base of the second electrode finger is shorter than the distance between the tip of the other first electrode finger and the base of the second electrode finger. The side of the first electrode finger with the shorter distance, and the side of the second virtual electrode finger opposite the second electrode finger, with the shorter distance, are designated as the first side. The side opposite to the first side is designated as the second side. If the distance between the tip of one of the second electrode fingers adjacent to any first electrode finger and the base of the first electrode finger is shorter than the distance between the tip of the other second electrode finger and the base of the first electrode finger, then the side of the second electrode finger with the shorter distance and the side of the first dummy electrode opposite the first electrode finger are designated as the second side. The side opposite to the second side is designated as the first side. The line connecting the centers of the multiple second gaps is designated as the fourth virtual line. The region on the second side of the second gap side portion of the first dummy electrode is designated as the first region; the region on the first side of the second gap side portion of the first dummy electrode is designated as the second region; the region on the second side of the second gap side portion of the first electrode finger is designated as the fifth region; the region on the first side of the second gap side portion of the first electrode finger is designated as the sixth region; in adjacent second electrode fingers, in the portion closer to the second busbar than the fourth dummy line, the region on the second side is designated as the third region; the region on the first side is designated as the fourth region; in the second electrode fingers, the region on the second side of the portion closer to the first busbar than the fourth dummy line is designated as the seventh region; and the region on the first side of the portion closer to the first busbar than the fourth dummy line is designated as the eighth region. In the first region, the third region, the sixth region, and the eighth region, the angle formed by the first or second side edge of each region and the third virtual line is an acute angle; in the second region, the fourth region, the fifth region, and the seventh region, the angle formed by the first or second side edge of each region and the third virtual line is an obtuse angle. The facility includes at least one of the following: a protrusion disposed in at least one of the first region, the third region, the sixth region, and the eighth region; and a recess disposed in at least one of the second region, the fourth region, the fifth region, and the seventh region.

4. The elastic wave device according to any one of claims 1 to 3, wherein, The piezoelectric substrate has a piezoelectric film and a high-velocity acoustic material layer, the high-velocity acoustic material layer comprising a high-velocity acoustic material, wherein the velocity of sound of a bulk wave propagating in the high-velocity acoustic material is higher than the velocity of sound of an elastic wave propagating in the piezoelectric film.

5. The elastic wave device according to claim 4, wherein, The elastic wave device further comprises a low-velocity material layer, which is stacked between the high-velocity material layer and the piezoelectric film, and includes a low-velocity material, wherein the velocity of the volume wave propagating in the low-velocity material is lower than the velocity of the volume wave propagating in the piezoelectric film.

6. The elastic wave device according to claim 4, wherein, The hypersonic material layer is a hypersonic support substrate comprising the hypersonic material.

7. The elastic wave device according to any one of claims 1 to 3, wherein, The piezoelectric substrate is a piezoelectric substrate including piezoelectric single crystals.

8. The elastic wave device according to claim 7, wherein, The piezoelectric single crystal is LiTaO3.

9. An elastic wave device, comprising: piezoelectric substrates; and IDT electrodes are disposed on the piezoelectric substrate. The IDT electrode has: First busbar; The second busbar is spaced apart from the first busbar; Multiple first electrode fingers, one end of which is connected to the first bus bar; Multiple second electrode fingers, one end of which is connected to the second bus bar; Multiple first dummy electrodes, connected to the second busbar, are configured such that their front ends are positioned opposite the first electrodes, separated by a second gap; and Multiple second dummy electrodes are connected to the first busbar, and their front ends are positioned opposite each other with a first gap between them, pointing towards the second electrodes. The first virtual line connecting the tips of multiple second electrode fingers is inclined relative to the direction of elastic wave propagation, which is orthogonal to the direction in which the first and second electrode fingers extend. If the distance between the tip of one of the second electrode fingers adjacent to any first electrode finger and the base of the first electrode finger is shorter than the distance between the tip of the other second electrode finger and the base of the first electrode finger, then the side of the second electrode finger with the shorter distance among the sides of the first electrode finger and the side of the second electrode finger with the shorter distance among the sides of the first dummy electrode opposite the first electrode finger are designated as the first side, and the side opposite to the first side is designated as the second side. If the distance between the tip of one of the first electrode fingers adjacent to any second electrode finger and the base of the second electrode finger is shorter than the distance between the tip of the other first electrode finger and the base of the second electrode finger, then the side of the first electrode finger with the shorter distance and the side of the second dummy electrode opposite the second electrode finger are designated as the second side. The side opposite to the second side is designated as the first side. The line connecting the centers of the multiple first gaps is designated as a second virtual line. The region on the first side of the first gap side portion of the second dummy electrode is designated as the first region; the region on the second side of the first gap side portion of the second dummy electrode is designated as the second region; the region on the first side of the first gap side portion of the second electrode finger is designated as the fifth region; the region on the second side of the first gap side portion of the second electrode finger is designated as the sixth region; in adjacent first electrode fingers, in the portion closer to the first busbar than the second dummy line, the region on the first side is designated as the third region; the region on the second side is designated as the fourth region; in the first electrode fingers, the region on the first side of the portion closer to the second busbar than the second dummy line is designated as the seventh region; and the region on the second side of the portion closer to the second busbar than the second dummy line is designated as the eighth region. In the first region, the third region, the sixth region, and the eighth region, the angle formed by the first side or the second side of each region and the first virtual line is an acute angle; in the second region, the fourth region, the fifth region, and the seventh region, the angle formed by the first side or the second side of each region and the first virtual line is an obtuse angle. The region is provided with at least one of a protrusion and a recess, wherein the protrusion is provided in at least one of the first region, the third region, the sixth region and the eighth region, and the recess is provided in at least one of the second region, the fourth region, the fifth region and the seventh region.

10. The elastic wave device according to claim 9, wherein, When the first electrode finger and the second electrode finger are observed along the direction of elastic wave propagation, the overlapping area, i.e., the intersection area, has a central region located in the center of the extending direction of the first electrode finger and the second electrode finger, and a first low-sound speed region and a second low-sound speed region disposed on two outer sides of the central region. The recess or the protrusion is disposed in the first low-sound speed region and the second low-sound speed region.

11. The elastic wave device according to claim 9 or 10, wherein, The elastic wave device has a protrusion disposed in at least one of the first region, the third region, the sixth region, and the eighth region, and a recess disposed in at least one of the second region, the fourth region, the fifth region, and the seventh region.

12. The elastic wave device according to claim 11, wherein, The elastic wave device has the recesses provided in the second region and the fifth region, and the convexes provided in the first region and the sixth region.

13. The elastic wave device according to claim 12, wherein, At least one of the portions of the second region and the third region that are opposite each other in the direction of elastic wave propagation, and the portions of the sixth region and the seventh region that are opposite each other in the direction of elastic wave propagation, has the recess provided in the second region and the seventh region, and the protrusion provided in the third region and the sixth region.

14. The elastic wave device according to claim 9 or 10, wherein, The third virtual line connecting the tips of multiple first electrode fingers is inclined relative to the direction of elastic wave propagation. In a pair of first electrode fingers adjacent to any second electrode finger, the distance between the tip of one first electrode finger and the base of the second electrode finger is shorter than the distance between the tip of the other first electrode finger and the base of the second electrode finger. The side of the first electrode finger with the shorter distance, and the side of the second virtual electrode finger opposite the second electrode finger, with the shorter distance, are designated as the first side. The side opposite to the first side is designated as the second side. If the distance between the tip of one of the second electrode fingers adjacent to any first electrode finger and the base of the first electrode finger is shorter than the distance between the tip of the other second electrode finger and the base of the first electrode finger, then the side of the second electrode finger with the shorter distance and the side of the first dummy electrode opposite the first electrode finger are designated as the second side. The side opposite to the second side is designated as the first side. The line connecting the centers of the multiple second gaps is designated as the fourth virtual line. The region on the second side of the second gap side portion of the first dummy electrode is designated as the first region; the region on the first side of the second gap side portion of the first dummy electrode is designated as the second region; the region on the second side of the second gap side portion of the first electrode finger is designated as the fifth region; the region on the first side of the second gap side portion of the first electrode finger is designated as the sixth region; in adjacent second electrode fingers, in the portion closer to the second busbar than the fourth dummy line, the region on the second side is designated as the third region; the region on the first side is designated as the fourth region; in the second electrode fingers, the region on the second side of the portion closer to the first busbar than the fourth dummy line is designated as the seventh region; and the region on the first side of the portion closer to the first busbar than the fourth dummy line is designated as the eighth region. In the first region, the third region, the sixth region, and the eighth region, the angle formed by the first or second side edge of each region and the third virtual line is an acute angle; in the second region, the fourth region, the fifth region, and the seventh region, the angle formed by the first or second side edge of each region and the third virtual line is an obtuse angle. The facility includes at least one of the following: a protrusion disposed in at least one of the first region, the third region, the sixth region, and the eighth region; and a recess disposed in at least one of the second region, the fourth region, the fifth region, and the seventh region.

15. The elastic wave device according to claim 9 or 10, wherein, The piezoelectric substrate has a piezoelectric film and a high-velocity acoustic material layer, the high-velocity acoustic material layer comprising a high-velocity acoustic material, wherein the velocity of sound of a bulk wave propagating in the high-velocity acoustic material is higher than the velocity of sound of an elastic wave propagating in the piezoelectric film.

16. The elastic wave device according to claim 15, wherein, The elastic wave device further comprises a low-velocity material layer, which is stacked between the high-velocity material layer and the piezoelectric film, and includes a low-velocity material, wherein the velocity of the volume wave propagating in the low-velocity material is lower than the velocity of the volume wave propagating in the piezoelectric film.

17. The elastic wave device according to claim 15, wherein, The hypersonic material layer is a hypersonic support substrate comprising the hypersonic material.

18. The elastic wave device according to claim 9 or 10, wherein, The piezoelectric substrate is a piezoelectric substrate including piezoelectric single crystals.

19. The elastic wave device according to claim 18, wherein, The piezoelectric single crystal is LiTaO3.

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