Elastic wave device, communication device, and piezoelectric substrate

Abstract

The present invention improves the frequency characteristics of an elastic wave device. This elastic wave device is provided with: a piezoelectric body having a first surface; and an electrode including an IDT electrode on the first surface. The piezoelectric body has a first end surface that is positioned on a first side in a first direction orthogonal to the extension direction of one of electrode fingers and that is connected to the first surface. A first angle formed by an extension line of the first surface and a tangent line at an arbitrary point of the first end surface is less than 90°.

Description

Acoustic wave devices, communication devices, piezoelectric substrates

[0001] The present disclosure relates to an acoustic wave device, a communication device including the acoustic wave device, and a piezoelectric substrate.

[0002] Patent Document 1 discloses an example of the configuration of an acoustic wave device.

[0003] International Publication No. 2016 / 185772

[0004] An elastic wave device according to one aspect of the present disclosure comprises a piezoelectric body having a first surface, and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has an end surface located on a first side in a first direction that is perpendicular to an extension direction of any of the plurality of electrode fingers among directions parallel to the first surface, and the first end surface is connected to the first surface, and in a cross section of the piezoelectric body cut in a plane parallel to the first direction and perpendicular to the first surface, a first angle formed between an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is greater than or equal to 70° and less than 90°.

[0005] An elastic wave device according to another aspect of the present disclosure comprises a piezoelectric body having a first surface and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has an end surface located on a first side in a first direction parallel to the first surface and perpendicular to an extension direction of any of the plurality of electrode fingers, the first end surface being connected to the first surface, wherein in a cross section of the piezoelectric body taken along a plane parallel to the first direction and perpendicular to the first surface, a first angle formed between an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is less than 90°, and where p is the average value of the spacing between the plurality of electrode fingers in the first direction, the height of the first end surface is 0.5p or more and 2.0p or less.

[0006] an elastic wave device according to another aspect of the present disclosure, comprising: a support substrate; a piezoelectric body positioned on the support substrate and having a first surface opposite the support substrate; and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has an end surface positioned on a first side in a first direction parallel to the first surface and perpendicular to an extension direction of any of the plurality of electrode fingers, the first end surface being connected to the first surface; in a cross section of the piezoelectric body taken along a plane parallel to the first direction and perpendicular to the first surface, a first angle formed between an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is less than 90°; and, when an average value of the spacing between the plurality of electrode fingers in the first direction is p, a height from a lower surface of the support substrate opposite the first surface to the first surface is 0.5p or more and 2.0p or less.

[0007] An elastic wave device according to another aspect of the present disclosure comprises a piezoelectric body having a first surface, and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has an end surface located on a first side in a first direction, among directions parallel to the first surface, that is perpendicular to an extension direction of any of the plurality of electrode fingers, and the first end surface is connected to the first surface, and in a cross section of the piezoelectric body taken along a plane parallel to the first direction and perpendicular to the first surface, a first angle formed between an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is less than 90°, the electrode includes an end electrode closest to the first end surface, and when the average spacing between the plurality of electrode fingers in the first direction is p, the shortest distance between the end electrode and the first end surface is 5p or less.

[0008] A piezoelectric substrate according to another aspect of the present disclosure comprises a piezoelectric body having a first surface, the piezoelectric body having an end surface located on a first side in a first direction that is a direction parallel to the first surface, the first end surface being connected to the first surface, and in a cross section of the piezoelectric body cut in a plane parallel to the first direction and perpendicular to the first surface, a first angle formed between an extension line of the first surface in the first direction and a tangent line at any point of the first end surface is greater than or equal to 70° and less than 90°.

[0009] FIG. 1 is a schematic enlarged view of a side cross section of an elastic wave device according to a first embodiment of the present disclosure. FIG. 2 is a schematic plan view of an elastic wave device according to the first embodiment of the present disclosure. FIG. 3 is a schematic cross-sectional view of an elastic wave device according to the first embodiment of the present disclosure. FIG. 4 is a graph showing frequency characteristics of elastic wave devices according to examples and comparative examples of the present disclosure. FIG. 5 is an enlarged view of a portion of the graph showing frequency characteristics of an elastic wave device according to another example of the present disclosure. FIG. 6 is an enlarged view of a portion of the graph showing frequency characteristics of an elastic wave device according to another example of the present disclosure. FIG. 7 is a schematic plan view of an elastic wave device according to a second embodiment of the present disclosure. FIG. 8 is a schematic cross-sectional view of an elastic wave device according to the second embodiment of the present disclosure. FIG. 9 is a graph showing frequency characteristics of elastic wave devices according to another example and comparative example of the present disclosure. FIG. 10 is an enlarged view of a portion of the graph showing frequency characteristics of elastic wave devices according to another example and comparative example of the present disclosure. FIG. 11 is a schematic plan view of an elastic wave device according to a third embodiment of the present disclosure. FIG. 12 is a schematic cross-sectional view of an elastic wave device according to the third embodiment of the present disclosure. FIG. 13 is a schematic enlarged view of a side cross section of an elastic wave device according to the third embodiment of the present disclosure. FIG. 14 is a schematic view of a communication device according to each embodiment of the present disclosure.

[0010] [Embodiment 1] An elastic wave device according to this embodiment will be described in detail below. For ease of explanation, components having the same functions as those described in Embodiment 1 will be denoted by the same reference numerals in the following embodiments, and their description will not be repeated. For simplicity, descriptions of well-known technical matters will also be omitted as appropriate. Unless otherwise specified, the components, materials, and numerical values ​​described in this specification are merely examples. Therefore, for example, unless otherwise specified, the positional relationship of each component is not limited to the example shown in each figure. Furthermore, the illustrations of each component are not necessarily to scale.

[0011] (Outline of Elastic Wave Device) FIG. 2 is a schematic plan view of an elastic wave device 1 according to this embodiment. FIG. 3 is a schematic side cross-sectional view of the elastic wave device 1 according to this embodiment, particularly a cross-sectional view taken along line III-III in FIG. 2 . In other words, FIG. 3 shows a side cross-section of the elastic wave device 1 taken along a plane parallel to a first direction D1 and a film thickness direction DT (described below) and passing through multiple electrode fingers 32 and floating electrode 4. In further words, the side cross-sectional view shown in FIG. 3 shows a cross-section of the piezoelectric body 2 taken along a plane parallel to a first direction D1 and perpendicular to a first surface 21 (described below). For clarity of explanation, this disclosure will describe a case in which the elastic wave device 1 includes a single elastic wave element or elastic wave resonator. However, this is not limiting, and the elastic wave device 1 according to this disclosure may include multiple elastic wave elements or elastic wave resonators arranged in parallel.

[0012] As shown in FIGS. 2 and 3 , the acoustic wave device 1 includes a piezoelectric body 2. The piezoelectric body 2 is made of, for example, a single crystal material. An example of the piezoelectric body 2 is lithium tantalate (LiTaO), also known as LT. ３ Lithium niobate (LiNbO), also known as LN ３ In the present disclosure, the case where the piezoelectric body 2 is made of LT is mainly exemplified. In the present disclosure, a substrate provided with the piezoelectric body 2 is also referred to as a piezoelectric substrate.

[0013] The piezoelectric body 2 has a first surface 21. The first surface 21 is, for example, the upper surface of the piezoelectric body 2 in the thickness direction DT. In this embodiment, the thickness direction DT is a plane perpendicular to the first surface 21. The acoustic wave device 1 includes an interdigital transducer (IDT) electrode 3 located on the first surface 21 of the piezoelectric body 2. The IDT electrode 3 excites an acoustic wave and is also referred to as an excitation electrode.

[0014] The IDT electrode 3 includes, for example, a bus bar 31A extending on the first surface 21 and a bus bar 31B facing the bus bar 31A and extending in substantially the same direction as the extension direction of the bus bar 31A. The IDT electrode 3 also includes a plurality of electrode fingers 32, including electrode fingers 32A extending from the bus bar 31A toward the bus bar 31B and electrode fingers 32B extending from the bus bar 31B toward the bus bar 31A. The extension direction DE of the electrode fingers 32A and the electrode fingers 32B may be, for example, perpendicular to the extension direction of the bus bar 31A or the bus bar 31B. In the present disclosure, the terms "two directions are the same" or "two directions are parallel" do not necessarily refer to the two directions being strictly parallel. In the present disclosure, for example, "the extension directions of two members are the same" means that the extension directions of the two members may differ within the range of manufacturing tolerances of the two members.

[0015] The electrode fingers 32A and the electrode fingers 32B are alternately positioned at a pitch p in a first direction D1 that is perpendicular to the extension direction DE, for example, among directions parallel to the first surface 21. In the present disclosure, the pitch p refers to the distance between the centers of two electrode fingers 32 adjacent to each other in the first direction D1. Therefore, the multiple electrode fingers 32 are arranged at a pitch p in the first direction D1. In this case, the extension direction of the bus bar 31A and the bus bar 31B may be substantially parallel to the first direction D1.

[0016] In the present disclosure, a case will be described in which the interval between two adjacent electrode fingers 32 in the first direction D1 is a constant pitch p, but this is not limited to this. For example, the interval between two adjacent electrode fingers 32 in the first direction D1 may vary depending on the pair of the two electrode fingers 32. In this case, in the present disclosure, the pitch p may refer to the average value of the interval between two adjacent electrode fingers 32 in the first direction D1.

[0017] In this embodiment, the configuration of the IDT electrode 3 is not limited to the configuration shown in FIG. 2 . For example, the arrangement direction of the multiple electrode fingers 32 may be different from a direction perpendicular to the extension direction DE of each electrode finger 32, in other words, different from the first direction D1. In this case, the extension direction of the busbars 31A and 31B may be different from the first direction D1. Furthermore, the extension direction DE of each electrode finger 32 may differ depending on the electrode finger 32. In this case, the first direction D1 may be a direction perpendicular to the extension direction DE of any of the electrode fingers 32.

[0018] Each electrode finger 32 has a width W1 along the first direction D1. In the present disclosure, a case where the width W1 of each electrode finger 32 is constant will be described, but this is not limiting. For example, the width of each electrode finger 32 along the first direction D1 may vary depending on the electrode finger 32. In this case, the width W1 in the present disclosure may refer to the average value of the widths of each electrode finger 32 along the first direction D1. In addition, in the present disclosure, the value obtained by dividing the width W1 by the pitch p may be referred to as the duty ratio.

[0019] Each electrode finger 32 has a thickness T1 along the film thickness direction DT. In the present disclosure, a case where the thickness T1 of each electrode finger 32 is constant will be described, but this is not limited to this. For example, the thickness of each electrode finger 32 along the film thickness direction DT may differ depending on the electrode finger 32. Furthermore, even for the same electrode finger 32, the thickness of the electrode finger 32 along the film thickness direction DT may differ depending on the position within the electrode finger 32. In this case, the thickness T1 in the present disclosure may refer to the average value of the thickness of each electrode finger 32 along the film thickness direction DT.

[0020] The elastic wave device 1 according to this embodiment further includes a floating electrode 4. The floating electrode 4 is located on the first surface 21 of the piezoelectric body 2 and is electrically independent from other electrodes on the first surface 21, including portions of the IDT electrode 3. In particular, the floating electrode 4 is located at least at an end on the first side in the first direction D1 of the first surface 21, closer to the IDT electrode 3. In this embodiment, the floating electrode 4 may be located at both ends of the first surface 21, closer to the IDT electrode 3 in the first direction D1. The floating electrode 4 may have the function of improving the reflectivity of elastic waves propagating through the piezoelectric body 2.

[0021] The floating electrode 4 has a width W2 along the first direction D1. In this embodiment, the width W2 is greater than the width W1. In this embodiment, the thickness of the floating electrode 4 along the film thickness direction DT may be the same as the thickness T1 of each electrode finger 32 along the film thickness direction DT. In this disclosure, "the two members have the same thickness" does not only refer to the case where the thicknesses of the two members are strictly the same, but also allows for a difference in the thicknesses of the two members within the range of manufacturing tolerance, for example.

[0022] (End Face of Elastic Wave Device) The elastic wave device 1 has an end face 5 located on a first side in the first direction D1. In particular, in this embodiment, the end face 5 includes a first end face 51 that is included in the piezoelectric body 2 and that connects to the first surface 21. In other words, the piezoelectric body 2 is located on the first side in the first direction D1 and has a first end face that connects to the first surface 21. In this embodiment, in addition to the first end face 51, the piezoelectric body 2 may have another end face that is not connected to the first surface 21 but that forms part of the end face 5. The elastic wave device 1 may also have an end face 5 on a second side that is opposite the first side in the first direction D1.

[0023] In this embodiment, the first end face 51 has a height H1 from the lower end to the upper end along the film thickness direction DT. Of the end faces of the piezoelectric body 2 located on the first direction D1 side, the height H1 includes only the height of the first end face 51 that connects to the first surface 21. In other words, the height H1 does not include the height of the other end faces of the piezoelectric body 2 that do not connect to the first surface 21. In the present disclosure, "two surfaces connect" may refer to either of the ends of the two surfaces being in contact with each other.

[0024] The configuration of the elastic wave device 1 in the vicinity of the first end face 51 will be described in detail with reference to FIG. 1 . FIG. 1 is a schematic enlarged side cross-sectional view of the elastic wave device 1 according to this embodiment, particularly illustrating an enlarged view of region I shown in FIG. 3 , in other words, the vicinity of the first end face 51 included in the end face 5 on the first side. In other words, FIG. 1 illustrates a cross-section of the elastic wave device 1 including the piezoelectric body 2 taken along a plane parallel to the first direction D1 and perpendicular to the first surface 21. In this embodiment, the first end face 51 included in the end face 5 located on the second side in the first direction D1 may have the same configuration as the first end face 51 shown in FIG. 1 , except that the left and right sides in the first direction D1 are reversed.

[0025] (First Angle) In this embodiment, an extension line of the first surface 21 in the first direction D1 is referred to as extension line 21E as shown in FIG. 1 . Furthermore, in a cross section of the elastic wave device 1 according to this embodiment parallel to the first direction D1, the angle formed between extension line 21E and the first end surface 51 on the exterior side of the piezoelectric body 2 is referred to as first angle A1. While the first end surface 51 is described as being flat in this disclosure as an example, this is not limiting, and the first end surface 51 may be a curved surface, for example. In this case, the first angle A1 may be the angle formed between extension line 21E and a tangent at any point to the first end surface 51 on the exterior side of the piezoelectric body 2.

[0026] In this embodiment, the first angle A1 is less than 90°. Here, the direction parallel to the normal direction of the first end face 51 and directed from the first end face 51 toward the interior of the piezoelectric body 2 is defined as the second direction D2. In this case, because the first angle A1 is less than 90°, the surface of the piezoelectric body 2 opposite the first surface 21 in the film thickness direction DT is located in the second direction D2 from any point on the first end face 51; in other words, a portion of the piezoelectric body 2 that is different from the first surface 21. Therefore, the first end face 51 does not face the first surface 21 on the interior side of the piezoelectric body 2.

[0027] A portion of the elastic waves excited by the IDT electrode 3 of the elastic wave device 1 and propagating through the piezoelectric body 2 propagates in the arrangement direction of the plurality of electrode fingers 32, for example, in the first direction D1. Furthermore, a portion of the elastic waves is reflected by the first end surface 51 of the piezoelectric body 2. As a result, the elastic wave device 1 improves the intensity of the elastic wave, called the principal vibration, which has a desired frequency among the elastic waves propagating through the piezoelectric body 2.

[0028] On the other hand, the elastic waves propagating through the piezoelectric body 2 may include elastic waves called spurious waves that have a frequency different from the frequency of the main vibration. In general, it is possible to improve the frequency characteristics of an elastic wave device by reducing the intensity of the spurious waves while maintaining the intensity of the main vibration of the elastic waves propagating through the piezoelectric body.

[0029] As described above, when the first angle A1 is less than 90°, when an elastic wave propagating through the piezoelectric body 2 is reflected by the first end face 51, part of the elastic wave propagates in the second direction D2, which is different from the direction from the first end face 51 toward the first surface 21. Therefore, by reflecting the elastic wave propagating through the piezoelectric body 2 at the first end face 51, the elastic wave device 1 causes part of the spurious components of the elastic wave to propagate in a direction different from the first surface 21 on which the IDT electrode 3 is located, and leaks from the piezoelectric body 2 to the outside of the elastic wave device 1. Therefore, the elastic wave device 1 reduces the spurious components propagating through the piezoelectric body 2.

[0030] On the other hand, in this embodiment, first angle A1 is equal to or greater than 70°. This reduces the propagation of the main vibration of the elastic waves reflected at first end surface 51 in a direction different from that of first surface 21. Therefore, elastic wave device 1 maintains the intensity of the main vibration propagating through piezoelectric body 2 even after the elastic waves propagating through piezoelectric body 2 are reflected at first end surface 51.

[0031] As described above, in an elastic wave device 1 in which the first angle A1 is equal to or greater than 70° and less than 90°, the intensity of the spurious components is reduced while maintaining the intensity of the primary vibration of the elastic waves propagating through the piezoelectric body 2. Therefore, the frequency characteristics of the elastic wave device 1 are improved by this configuration. From the perspective of further maintaining the intensity of the primary vibration propagating through the piezoelectric body 2, the first angle A1 may be equal to or greater than 80°, or even equal to or greater than 88°. With this configuration, the piezoelectric substrate including the piezoelectric body 2 according to this embodiment reduces the intensity of the spurious components while maintaining the intensity of the primary vibration of the elastic waves propagating through the piezoelectric body 2. Therefore, a piezoelectric substrate including the piezoelectric body 2 with this configuration improves the characteristics of the elastic waves propagating through the piezoelectric body 2.

[0032] (Height of First End Face) As described above, if the average value of the spacing between the electrode fingers 32 in the first direction D1 is the pitch p, in this embodiment, the height H1 of the first end face 51 is 0.5p or more and 2.0p or less.

[0033] When height H1 is 2.0p or less, some spurious components of the elastic waves propagating through piezoelectric body 2 may pass through the side opposite first surface 21 from first end face 51. As a result, elastic wave device 1 reduces the reflection of some spurious components of the elastic waves propagating through piezoelectric body 2 at first end face 51, causing the spurious components to leak from piezoelectric body 2 to the outside of elastic wave device 1. Therefore, elastic wave device 1 reduces spurious components propagating through piezoelectric body 2. Additionally, as described above, because first angle A1 is less than 90°, elastic wave device 1 further reduces spurious components propagating through piezoelectric body 2.

[0034] On the other hand, when height H1 is 0.5p or greater, most of the main vibration of the elastic waves propagating through piezoelectric body 2 is reflected by first end surface 51. Therefore, elastic wave device 1 reflects the elastic waves propagating through piezoelectric body 2 at first end surface 51, thereby maintaining the intensity of the main vibration propagating through piezoelectric body 2.

[0035] As described above, elastic wave device 1 having first angle A1 less than 90° and height H1 between 0.5p and 2.0p reduces the intensity of spurious components while maintaining the intensity of the primary vibration of the elastic waves propagating through piezoelectric body 2. Therefore, the above configuration improves the frequency characteristics of elastic wave device 1. From the viewpoint of further maintaining the intensity of the primary vibration propagating through piezoelectric body 2, first angle A1 may be 80° or greater.

[0036] (Distance between End Electrode and First End Surface) As described above, the floating electrode 4 is located closer to the end of the first surface 21 in the first direction D1 than the IDT electrode 3. Therefore, in this embodiment, the floating electrode 4 is the end electrode on the first surface 21 that is closest to the first end surface 51. The shortest distance between the floating electrode 4, which is an end electrode, and the first end surface 51 is defined as distance L1. In this embodiment, if the average value of the spacing between the multiple electrode fingers 32 in the first direction D1 is defined as pitch p, then distance L1 is 5p or less. In this disclosure, "distance L1 is 5p or less" includes distance L1 being 0. In other words, the floating electrode 4, which is an end electrode in this embodiment, may contact the end of the first end surface 51 on the first surface 21 side.

[0037] In this embodiment, the distance L1, which is the shortest distance between the floating electrode 4, which is an end electrode, and the first end surface 51, is 5p or less, which corresponds to the floating electrode 4 being located near the first end surface 51. The end electrode has the function of promoting excitation of elastic waves reflected at the first end surface 51 among the elastic waves propagating through the piezoelectric body 2. Therefore, the floating electrode 4 located near the first end surface 51 promotes excitation of the main vibration among the elastic waves reflected at the first end surface 51. Therefore, the elastic wave device 1 maintains the intensity of the main vibration propagating through the piezoelectric body 2. In addition, as described above, because the first angle A1 is less than 90°, the elastic wave device 1 reduces spurious signals propagating through the piezoelectric body 2.

[0038] As described above, elastic wave device 1 in which first angle A1 is less than 90° and distance L1 is 5p or less reduces the intensity of spurious components while maintaining the intensity of the primary vibration of the elastic waves propagating through piezoelectric body 2. Therefore, the above configuration improves the frequency characteristics of elastic wave device 1. From the viewpoint of further maintaining the intensity of the primary vibration propagating through piezoelectric body 2, distance L1 may be 1p or less, or even 0.1p or less.

[0039] The floating electrode 4 according to this embodiment is an end electrode and is electrically independent from the other electrodes located on the first surface 21 that are different from the floating electrode 4. Therefore, the shape or arrangement pattern of the floating electrode 4 can be made different from, for example, the multiple electrode fingers 32 of the IDT electrode 3 that have the function of exciting the primary vibration. Therefore, the floating electrode 4 improves the degree of freedom in designing the electrodes on the first surface 21, and enables the design of an elastic wave device 1 that, for example, further promotes excitation of the primary vibration of the elastic wave propagating through the piezoelectric body 2.

[0040] On the other hand, the floating electrode 4 has a different shape or arrangement pattern from the electrode fingers 32. In particular, the width W2 of the floating electrode 4 is greater than the width W1, which is the average width of the electrode fingers 32. Therefore, the floating electrode 4 may excite spurious signals among the acoustic waves propagating in the vicinity. However, in this embodiment, the floating electrode 4 is located near the first end surface 51, which has the function of reflecting spurious signals propagating through the piezoelectric body 2 and leaking them outside the acoustic wave device 1. Therefore, the acoustic wave device 1 efficiently leaks spurious signals excited near the floating electrode 4 to the outside of the acoustic wave device 1 via the first end surface 51. Therefore, the acoustic wave device 1 more efficiently reduces spurious signals propagating in the piezoelectric body 2. In particular, the acoustic wave device 1 more efficiently reduces spurious signals propagating in the piezoelectric body 2 even when the width W2 is greater than the width W1, in other words, even when the shape of the floating electrode 4 is significantly different from the shape of each electrode finger 32.

[0041] In general, in an elastic wave device, the width of the electrode at the end of the piezoelectric body in the direction of propagation of elastic waves is half the average width of the multiple electrode fingers on the piezoelectric body, thereby reducing spurious signals excited near the end electrode. However, in this embodiment, width W2 is different from half of width W1; in other words, width W2 is greater or less than half of width W1. Meanwhile, as described above, floating electrode 4 is located near first end surface 51, which has the function of reflecting spurious signals propagating through piezoelectric body 2 and leaking them outside elastic wave device 1. Therefore, elastic wave device 1 according to this embodiment can reduce spurious signals caused by width W2 being different from half of width W1.

[0042] (Comparative Verification Between Example and Comparative Example: First Angle) To confirm the improvement in frequency characteristics of the elastic wave device 1 according to this embodiment, the frequency characteristics of the elastic wave devices according to the example and comparative example were compared and verified by simulation.

[0043] First, the frequency characteristics of the elastic wave devices according to Example 1, Example 2, and Comparative Example 1 were compared and verified. The elastic wave devices according to Example 1, Example 2, and Comparative Example 1 all had the same configuration as elastic wave device 1 according to this embodiment, except for the value of first angle A1. In each of the elastic wave devices, thickness T1 was 8% of the total thickness of the elastic wave device, duty ratio was 0.50, width W2 was 1.26p, cut angle of piezoelectric body 2 was 42°, and total number of electrode fingers 32 was 200. In Example 1, Example 2, and Comparative Example 1, first angle A1 was 70°, 80°, and 90°, respectively.

[0044] Simulation results for the phase characteristics of the elastic wave devices according to Example 1, Example 2, and Comparative Example 1 are summarized in FIGS. 4 and 5 . FIG. 4 is a graph showing the phase characteristics of the elastic wave devices according to Example 1, Example 2, and Comparative Example 1. FIG. 5 is an enlarged graph of region V in the graph shown in FIG. 4 . In FIGS. 4 and 5 , the phase characteristics of the elastic wave devices according to Example 1, Example 2, and Comparative Example 1 are indicated by solid lines, dashed lines, and dotted lines. In the graphs of FIGS. 4 and 5 , the horizontal axis represents frequency, and the vertical axis represents the phase of impedance in each elastic wave device. Hereinafter, the phase of impedance in an elastic wave device will be simply referred to as phase.

[0045] In general, in an elastic wave device, the theoretical phase can range from a minimum of -90° to a maximum of 90°. Furthermore, in general, in the phase characteristics of an elastic wave device, the closer the phase at a certain frequency is to 90°, the more the excitation of elastic waves having that frequency in the elastic wave device is promoted. Conversely, the closer the phase at a certain frequency is to -90°, the more the excitation of elastic waves having that frequency in the elastic wave device is reduced. Therefore, in general, the frequency characteristics of an elastic wave device can be improved by bringing the phase at a frequency corresponding to the principal vibration closer to 90° and the phase at a frequency corresponding to spurious signals other than the principal vibration closer to -90°.

[0046] The elastic wave devices according to Example 1, Example 2, and Comparative Example 1 each excite an elastic wave having a frequency near 2000 MHz as the primary vibration. As shown in the graph of Fig. 4 , the phase near 2000 MHz in the elastic wave devices according to Example 1 and Example 2 is approximately 90°, which is roughly the same as the phase near 2000 MHz in the elastic wave device according to Comparative Example 1. Thus, the elastic wave devices according to Example 1 and Example 2 maintain excitation of the primary vibration to a certain extent compared to the elastic wave device according to Comparative Example 1.

[0047] 4 , the phase of a frequency corresponding to a portion of the principal vibration in the elastic wave device according to Example 2 is larger than the phase of the same frequency in the elastic wave device according to Example 1. This corresponds to the fact that, in this embodiment, the larger the first angle A1, the more the principal vibration reflected at first end surface 51 is reduced from leaking from piezoelectric body 2 to the outside of elastic wave device 1.

[0048] In contrast, in the elastic wave devices according to Example 1, Example 2, and Comparative Example 1, elastic waves having frequencies of approximately 1970 MHz or less correspond to spurious signals. As shown in the graph in Fig. 5 , the elastic wave devices according to Example 1 and Example 2 reduce the phase of frequencies corresponding to some of the spurious signals compared to the elastic wave device according to Comparative Example 1. As a result, the elastic wave devices according to Example 1 and Example 2 reduce spurious excitation compared to the elastic wave device according to Comparative Example 1.

[0049] 5 , the phase of the frequency corresponding to the spurious response in the elastic wave device according to Example 1 tends to be smaller than the phase of the frequency corresponding to the spurious response in the elastic wave device according to Example 2. This corresponds to the fact that, in this embodiment, the smaller the first angle A1, the more efficiently the spurious response reflected at first end surface 51 leaks from piezoelectric body 2 to the outside of elastic wave device 1.

[0050] (Comparative Verification Between Examples and Comparative Examples: Height of First End Face) Next, the frequency characteristics of the elastic wave devices according to Examples 3, 4, and 5 were compared. The elastic wave devices according to Examples 3, 4, and 5 all have the same configuration as the elastic wave device according to Example 2, except for the value of height H1. In Examples 3, 4, and 5, height H1 was set to 1p, 1.5p, and 2p, respectively.

[0051] Simulation results of the phase characteristics of the elastic wave devices according to Examples 3, 4, and 5 are summarized in FIGS. 6 and 7 . FIG. 6 is a graph showing the phase characteristics of the elastic wave devices according to Examples 3, 4, and 5. FIG. 7 is an enlarged graph of region VII of the graph shown in FIG. 6 . In FIGS. 6 and 7 , the phase characteristics of the elastic wave devices according to Examples 3, 4, and 5 are indicated by solid lines, dashed lines, and dotted lines. In the graphs of FIGS. 6 and 7 , the horizontal axis represents frequency, and the vertical axis represents phase.

[0052] The elastic wave devices according to Examples 3, 4, and 5 each excite an elastic wave having a frequency near 2000 MHz as the primary vibration. As shown in the graph of Fig. 6, the phase near 2000 MHz in the elastic wave devices according to Examples 3, 4, and 5 is all near 90°. This indicates that the elastic wave devices according to Examples 3, 4, and 5 each maintain excitation of the primary vibration to a certain extent.

[0053] In contrast, in the elastic wave devices according to Examples 3, 4, and 5, elastic waves having frequencies of approximately 1970 MHz or less correspond to spurious signals. As shown in the graph of Fig. 7 , the elastic wave devices according to Examples 3 and 4 have reduced phases of frequencies corresponding to some of the spurious signals compared to the elastic wave device according to Example 5. Furthermore, as shown in the graph of Fig. 7 , the elastic wave device according to Example 3 has reduced phases of frequencies corresponding to other spurious signals compared to the elastic wave device according to Example 4. This corresponds to the fact that, in this embodiment, as height H1 is smaller, spurious reflection at first end surface 51 is reduced, and spurious signals leak more efficiently from piezoelectric body 2 to the outside of elastic wave device 1.

[0054] Second Embodiment An elastic wave device 1 according to another embodiment will be described below. For convenience of explanation, the same reference numerals are used to designate components having the same functions as those described in the previous embodiment, and the description thereof will not be repeated.

[0055] (Support Substrate) Fig. 8 is a schematic plan view of the elastic wave device 1 according to this embodiment. Fig. 9 is a schematic side cross-sectional view of the elastic wave device 1 according to this embodiment, particularly a cross-sectional view taken along line IX-IX in Fig. 9. In other words, Fig. 9 shows a side cross-section of the elastic wave device 1 taken along a plane parallel to the first direction D1 and the film thickness direction DT and passing through the electrode fingers 32 and the floating electrode 4.

[0056] The elastic wave device 1 according to this embodiment has the same configuration as the elastic wave device 1 according to the previous embodiment, except that it further includes a support substrate 6 and that the piezoelectric body 2 has a partially different configuration.

[0057] The support substrate 6 is a substrate that supports the piezoelectric body 2 in the acoustic wave device 1. The support substrate 6 includes, for example, a first layer 61 and a second layer 62 stacked one on top of the other. The first layer 61 is also called a low acoustic velocity layer and is made of, for example, silicon oxide (SiO ２ The second layer 62 may be, for example, a silicon substrate. The thickness of the second layer 62 may be greater than the thickness of the first layer 61.

[0058] The acoustic wave device 1 includes, for example, a piezoelectric body 2 on a surface of the support substrate 6 that is closer to the first layer 61 than the second layer 62 in the thickness direction DT. The piezoelectric body 2 has a first surface 21 on which electrodes including the IDT electrode 3 and the floating electrode 4 are located, on the side opposite the support substrate 6.

[0059] The piezoelectric element 2 according to this embodiment is supported by the support substrate 6. Therefore, the elastic wave device 1 can reduce the attenuation of the elastic waves propagating through the piezoelectric element 2. Therefore, the elastic wave device 1 can more efficiently maintain the intensity of the main vibration propagating through the piezoelectric element 2.

[0060] In this embodiment, the end face 5 may include, in addition to the first end face 51, a second end face 52 of the first layer 61 and a third end face 53 of the second layer 62. In this embodiment, the first end face 51, the second end face 52, and the third end face 53 may be continuous. In this embodiment, the end face 5 has a height H2 along the film thickness direction DT from the lower end of the support substrate 6 on the side opposite the piezoelectric body 2 to the upper end on the first surface 21 side of the piezoelectric body 2. In other words, the height H2 is the height from the lower surface of the support substrate 6 on the side opposite the first surface 21 to the first surface 21. In this embodiment, the height H1 from the lower end to the upper end of the first end face 51 along the film thickness direction DT is smaller than the height H1 according to the previous embodiment.

[0061] The configuration of the elastic wave device 1 near the end face 5 will be described in detail with reference to Fig. 10 . Fig. 10 is a schematic enlarged view of a side cross section of the elastic wave device 1 according to this embodiment, particularly illustrating an enlarged view of the region X shown in Fig. 9 , in other words, the vicinity of the end face 5 on the first side in the first direction D1. In other words, Fig. 1 shows a portion of a cross section of the elastic wave device 1 according to this embodiment, which is parallel to the first direction D1 and the thickness direction DT. In this embodiment, the end face 5 located on the second side in the first direction D1 may have the same configuration as the end face 5 shown in Fig. 10 , except that the left and right sides in the first direction D1 are reversed.

[0062] In this preferred embodiment, the first angle A1 is also less than 90° as shown in Fig. 10. Therefore, for the same reason as described above, the elastic wave device 1 reduces spurious signals propagating through the piezoelectric body 2.

[0063] Furthermore, if the average spacing between the multiple electrode fingers 32 in the first direction D1 is defined as pitch p, then in this embodiment, the height H2 of the end face 5 is 0.5p or greater and 2.0p or less. When the height H2 is 2.0p or less, some of the spurious components of the elastic waves propagating through the piezoelectric body 2 are more likely to leak outside the elastic wave device 1 after being reflected by the first end face 51. Therefore, the elastic wave device 1 further reduces the spurious components propagating through the piezoelectric body 2.

[0064] Meanwhile, part of the main vibration of the elastic waves propagating through the piezoelectric body 2 is reflected by the first end surface 51 and then propagates toward the support substrate 6. However, because the height H2 is 0.5p or greater, the main vibration propagating toward the support substrate 6 is reflected by some portion of the support substrate 6 toward the piezoelectric body 2. Therefore, most of the main vibration propagating through the piezoelectric body 2 continues to propagate through the piezoelectric body 2 even after being reflected by the first end surface 51. Therefore, the elastic wave device 1 maintains the intensity of the main vibration propagating through the piezoelectric body 2.

[0065] As described above, elastic wave device 1 in which first angle A1 is less than 90° and height H2 is 0.5p or greater and 2.0p or less reduces the intensity of spurious components while maintaining the intensity of the primary vibration of the elastic waves propagating through piezoelectric body 2. Therefore, the above configuration improves the frequency characteristics of elastic wave device 1. From the perspective of further maintaining the intensity of the primary vibration propagating through piezoelectric body 2, first angle A1 may be 80° or greater.

[0066] (Comparative verification between the example and the comparative example: when a support substrate is provided) In order to confirm the improvement in the frequency characteristics of the elastic wave device 1 according to this embodiment, the frequency characteristics of the elastic wave devices according to the example and the comparative example were compared and verified by simulation.

[0067] In this embodiment, the frequency characteristics of elastic wave devices according to Example 6, Example 7, and Comparative Example 2 are compared and verified. The elastic wave devices according to Example 6, Example 7, and Comparative Example 2 all have the same configuration as elastic wave device 1 according to this embodiment, except for the value of first angle A1. In each of the elastic wave devices, the thickness T1 was 7% of the total thickness of the elastic wave device, the duty ratio was 0.50, the width W2 was 1.26p, the cut angle of piezoelectric body 2 was 50°, and the total number of electrode fingers 32 was 200. Furthermore, in each of the elastic wave devices, the thickness of piezoelectric body 2 was 0.5p, the thickness of first layer 61 was 0.25p, and the thickness of second layer 62 was sufficiently greater than the thickness of first layer 61. In each of the elastic wave devices, second layer 62 was a silicon substrate, and the orientation of Si in the silicon substrate was

[111] . In Example 6, Example 7, and Comparative Example 2, the first angle A1 was 70°, 80°, and 90°, respectively.

[0068] Simulation results of the phase characteristics of the elastic wave devices according to Example 6, Example 7, and Comparative Example 2 are summarized in FIGS. 11 and 12 . FIG. 11 is a graph showing the phase characteristics of the elastic wave devices according to Example 6, Example 7, and Comparative Example 2. FIG. 12 is an enlarged graph of region XII in the graph shown in FIG. 11 . In FIGS. 11 and 12 , the phase characteristics of the elastic wave devices according to Example 6, Example 7, and Comparative Example 2 are indicated by solid lines, dashed lines, and dotted lines. In the graphs of FIGS. 11 and 12 , the horizontal axis represents frequency, and the vertical axis represents phase.

[0069] The elastic wave devices according to Example 6, Example 7, and Comparative Example 2 each excite an elastic wave having a frequency near 1950 MHz as the primary vibration. As shown in the graph of Fig. 11 , the phase near 1950 MHz in the elastic wave devices according to Example 6 and Example 7 is approximately 90°, which is roughly the same as the phase near 1950 MHz in the elastic wave device according to Comparative Example 2. Thus, the elastic wave devices according to Example 6 and Example 7 maintain excitation of the primary vibration to a certain extent, even compared to the elastic wave device according to Comparative Example 2.

[0070] In contrast, in the elastic wave devices according to Example 6, Example 7, and Comparative Example 2, elastic waves having frequencies of approximately 1900 MHz or less correspond to spurious signals. As shown in the graph in Fig. 12, the elastic wave devices according to Example 6 and Example 7 reduce the phase of frequencies corresponding to some of the spurious signals compared to the elastic wave device according to Comparative Example 2. This indicates that the elastic wave devices according to Example 6 and Example 7 reduce spurious excitation compared to the elastic wave device according to Comparative Example 2.

[0071] Third Embodiment (Electrode Fingers as End Electrodes) Fig. 13 is a schematic plan view of an elastic wave device 1 according to this embodiment. Fig. 14 is a schematic side cross-sectional view of the elastic wave device 1 according to this embodiment, particularly a cross-sectional view taken along line XIV-XIV in Fig. 13. In other words, Fig. 14 shows a side cross-section of the elastic wave device 1 taken along a plane parallel to the first direction D1 and the thickness direction DT and passing through multiple electrode fingers 32.

[0072] The elastic wave device 1 according to this embodiment has the same configuration as the elastic wave device 1 according to the first embodiment, except that it does not include a floating electrode 4 and has a different configuration for the IDT electrode 3. In particular, in this embodiment, electrode finger 32E, which is one of the electrode fingers 32 included in the IDT electrode 3, is located near first end surfaces 51 at both ends in the first direction D1. Therefore, in this embodiment, electrode finger 32E is an end electrode.

[0073] 15 is a schematic enlarged view of a side cross section of the elastic wave device 1 according to this embodiment, particularly illustrating an enlarged view of region XV shown in FIG. 14 , in other words, the vicinity of the first end surface 51 on the first side in the first direction D1. In other words, FIG. 15 illustrates a portion of a cross section of the elastic wave device 1 according to this embodiment that is parallel to the first direction D1 and the thickness direction DT.

[0074] In this embodiment, the first angle A1 is less than 90°. Furthermore, if the average spacing between the multiple electrode fingers 32 in the first direction D1 is defined as pitch p, then the distance L1, which is the shortest distance between the electrode finger 32E serving as an end electrode and the first end face 51, is 5p or less. Therefore, for the same reasons as described above, the frequency characteristics of the elastic wave device 1 according to this embodiment are improved. From the perspective of further maintaining the strength of the main vibration propagating through the piezoelectric body 2, the first angle A1 may be 80° or greater.

[0075] The electrode finger 32E according to this embodiment is an end electrode and also a part of the electrode finger 32, in other words, a part of the IDT electrode 3. Therefore, the shape or arrangement pattern of the electrode finger 32E can be the same as, for example, any of the other electrode fingers 32 of the IDT electrode 3 that have the function of exciting the main vibration. Therefore, the electrode finger 32E reduces the occurrence of spurious signals in the vicinity and simplifies the arrangement pattern of the electrodes on the first surface 21, further simplifying the structure of the electrodes.

[0076] In this embodiment, the first angle A1 may be equal to or greater than 70°. The height H1 may be equal to or greater than 0.5p and equal to or less than 2.0p.

[0077] (Communication Device) Fig. 16 shows an example configuration of a communication device 7 according to each embodiment of the present disclosure. The communication device 7 performs wireless communication using radio waves. The communication device 7 includes an elastic wave device 1 according to at least one embodiment of the present disclosure. For example, a transmission filter 71 and a reception filter 72 in Fig. 16 may each include the elastic wave device 1 as a frequency filter.

[0078] In the communication device 7, a transmission information signal TIS containing information to be transmitted may be modulated and frequency-increased by an RF-IC (Radio Frequency-Integrated Circuit) 73 and converted into a transmission signal TS. The modulation and frequency-increasing of the transmission information signal TIS by the RF-IC 73 may include conversion into a high-frequency signal having a carrier frequency. A band-pass filter 74 may remove unwanted components from the transmission signal TS outside the transmission passband. Next, the transmission signal TS after the unwanted components have been removed may be amplified by an amplifier 75 and then input to the transmission filter 71.

[0079] The transmission filter 71 may remove unnecessary components outside the transmission passband from the transmission signal TS input via the transmission terminal. The transmission filter 71 may output the transmission signal TS after removing the unnecessary components to the antenna 76, for example, via an antenna terminal (not shown). The antenna 76 converts the transmission signal TS, which is an electrical signal input thereto, into radio waves as a wireless signal and can transmit the radio waves outside the communication device 7.

[0080] The antenna 76 can also convert received external radio waves into a received signal RS, which is an electrical signal. The antenna 76 may input the received signal RS to the receive filter 72, for example, via the antenna terminal described above. The receive filter 72 may remove unnecessary components outside the receive passband from the input received signal RS. The receive filter 72 may output the received signal RS after the unnecessary components have been removed to the amplifier 77 via the receive terminal. The output received signal RS may be amplified by the amplifier 77 and then input to the bandpass filter 78. The bandpass filter 78 may remove unnecessary components outside the receive passband from the amplified received signal RS. The received signal RS after the unnecessary components have been removed may be frequency-downshifted and demodulated by the RF-IC 73 and converted into a received information signal RIS.

[0081] The transmit information signal TIS and the receive information signal RIS may be low-frequency signals containing any information, including baseband signals. For example, the transmit information signal TIS and the receive information signal RIS may be analog audio signals or digitized audio signals. The passband of the radio signals may be set as appropriate and may comply with any of various standards.

[0082] The frequency characteristics of the acoustic wave device 1 included in the communication device 7 according to the present disclosure are improved for the reasons described above, and therefore the frequency characteristics of the communication device 7 according to the present disclosure are improved.

[0083] (Summary) An elastic wave device according to aspect 1 of the present disclosure comprises a piezoelectric body having a first surface, and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has an end surface located on a first side in a first direction that is perpendicular to an extension direction of any of the plurality of electrode fingers among directions parallel to the first surface, and the first end surface is connected to the first surface, and in a cross section of the piezoelectric body taken along a plane parallel to the first direction and perpendicular to the first surface, a first angle formed between an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is greater than or equal to 70° and less than 90°.

[0084] An elastic wave device according to a second aspect of the present disclosure may be configured in accordance with the first aspect, wherein the first angle is equal to or greater than 80° and less than 90°.

[0085] An elastic wave device according to a third aspect of the present disclosure may be configured in accordance with the second aspect, wherein the first angle is equal to or greater than 88° and less than 90°.

[0086] An elastic wave device according to a fourth aspect of the present disclosure comprises a piezoelectric body having a first surface, and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has a first end surface located on a first side in a first direction, which is parallel to the first surface and perpendicular to an extension direction of any of the plurality of electrode fingers, and which connects to the first surface; in a cross section of the piezoelectric body taken along a plane parallel to the first direction and perpendicular to the first surface, a first angle formed between an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is less than 90°; and, when the average spacing between the plurality of electrode fingers in the first direction is p, the height of the first end surface is 0.5p or more and 2.0p or less.

[0087] An elastic wave device according to a fifth aspect of the present disclosure may be configured in accordance with the fourth aspect, wherein the first angle is greater than or equal to 80° and less than 90°.

[0088] An elastic wave device according to a sixth aspect of the present disclosure comprises a support substrate, a piezoelectric body positioned on the support substrate and having a first surface opposite the support substrate, and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has a first end surface that is positioned on a first side in a first direction that is parallel to the first surface and perpendicular to an extension direction of any of the plurality of electrode fingers, and that is connected to the first surface, and in a cross section of the piezoelectric body taken along a plane parallel to the first direction and perpendicular to the first surface, a first angle formed between an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is less than 90°, and when the average spacing of the plurality of electrode fingers in the first direction is p, the height from the lower surface of the support substrate on the side opposite the first surface to the first surface is 0.5p or more and 2.0p or less.

[0089] An elastic wave device according to a seventh aspect of the present disclosure may be configured in accordance with the sixth aspect, wherein the first angle is equal to or greater than 80° and less than 90°.

[0090] An elastic wave device according to aspect 8 of the present disclosure comprises a piezoelectric body having a first surface, and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has a first end surface located on a first side in a first direction, which is parallel to the first surface and perpendicular to an extension direction of any of the plurality of electrode fingers, and which connects to the first surface; in a cross section of the piezoelectric body taken along a plane parallel to the first direction and perpendicular to the first surface, a first angle formed between an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is less than 90°; the electrode includes an end electrode closest to the first end surface; and when the average spacing between the plurality of electrode fingers in the first direction is p, the shortest distance between the end electrode and the first end surface is 5p or less.

[0091] An elastic wave device according to a ninth aspect of the present disclosure may be configured in accordance with the eighth aspect above, wherein the distance is 1p or less.

[0092] An elastic wave device according to a tenth aspect of the present disclosure may be configured in accordance with the ninth aspect above, wherein the distance is 0.1p or less.

[0093] A communication device according to an eleventh aspect of the present disclosure may include the acoustic wave device according to any one of the first to tenth aspects.

[0094] A piezoelectric substrate according to aspect 12 of the present disclosure comprises a piezoelectric body having a first surface, the piezoelectric body having an end surface located on a first side in a first direction that is parallel to the first surface, the first end surface being connected to the first surface, and in a cross section of the piezoelectric body cut in a plane parallel to the first direction and perpendicular to the first surface, a first angle formed between an extension of the first surface in the first direction and a tangent at any point on the first end surface is greater than or equal to 70° and less than 90°.

[0095] The invention according to the present disclosure has been described above with reference to the drawings and examples. However, the invention according to the present disclosure is not limited to the above-described embodiments. In other words, the invention according to the present disclosure can be modified in various ways within the scope of the present disclosure, and embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also within the technical scope of the invention according to the present disclosure. It should be noted that those skilled in the art would easily be able to make various modifications or alterations based on the present disclosure. It should also be noted that these modifications or alterations are within the scope of the present disclosure. For example, an elastic wave device 1 according to any embodiment other than embodiment 2 may include the support substrate 6 described in embodiment 2, and the piezoelectric element 2 may be located on the support substrate 6.

[0096] REFERENCE SIGNS LIST 1 Acoustic wave device 2 Piezoelectric body 3 IDT electrode 4 Floating electrode 5 End surface 6 Support substrate 7 Communication device 21 First surface 21E Extension line 32 Electrode finger 51 First end surface A1 First angle D1 First direction D2 Second direction

Claims

1. An elastic wave device comprising: a piezoelectric body having a first surface; and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has an end surface located on a first side in a first direction that is perpendicular to the extension direction of any of the plurality of electrode fingers among directions parallel to the first surface, and the first end surface is connected to the first surface; and in a cross section of the piezoelectric body cut in a plane parallel to the first direction and perpendicular to the first surface, a first angle formed by an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is greater than or equal to 70° and less than 90°.

2. The acoustic wave device according to claim 1, wherein the first angle is equal to or greater than 80° and less than 90°.

3. The acoustic wave device according to claim 2, wherein the first angle is equal to or greater than 88° and less than 90°.

4. An elastic wave device comprising: a piezoelectric body having a first surface; and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has a first end surface located on a first side in a first direction that is parallel to the first surface and perpendicular to an extension direction of any of the plurality of electrode fingers, and the first end surface is connected to the first surface; in a cross section of the piezoelectric body cut in a plane parallel to the first direction and perpendicular to the first surface, a first angle formed by an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is less than 90°; and where p is the average value of the spacing between the plurality of electrode fingers in the first direction, the height of the first end surface is 0.5p or more and 2.0p or less.

5. The acoustic wave device according to claim 4, wherein the first angle is equal to or greater than 80° and less than 90°.

6. An elastic wave device comprising: a support substrate; a piezoelectric body located on the support substrate and having a first surface opposite the support substrate; and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has a first end surface located on a first side in a first direction parallel to the first surface and perpendicular to an extension direction of any of the plurality of electrode fingers, the first end surface being connected to the first surface; in a cross section of the piezoelectric body cut in a plane parallel to the first direction and perpendicular to the first surface, a first angle formed by an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is less than 90°; and where p is the average value of the spacing between the plurality of electrode fingers in the first direction, the height from the underside of the support substrate on the side opposite the first surface to the first surface is 0.5p or more and 2.0p or less.

7. The acoustic wave device according to claim 6, wherein the first angle is equal to or greater than 80° and less than 90°.

8. An elastic wave device comprising: a piezoelectric body having a first surface; and an electrode including an IDT electrode having a plurality of electrode fingers arranged on the first surface, wherein the piezoelectric body has a first end surface located on a first side in a first direction, which is parallel to the first surface and perpendicular to an extension direction of any of the plurality of electrode fingers, and which connects to the first surface; in a cross section of the piezoelectric body taken along a plane parallel to the first direction and perpendicular to the first surface, a first angle formed by an extension line of the first surface in the first direction and a tangent line at any point on the first end surface is less than 90°; the electrode includes an end electrode closest to the first end surface; and when the average value of the spacing between the plurality of electrode fingers in the first direction is p, the shortest distance between the end electrode and the first end surface is 5p or less.

9. The acoustic wave device according to claim 8, wherein the shortest distance is 1p or less.

10. The acoustic wave device according to claim 9, wherein the shortest distance is 0.1p or less.

11. A communication device comprising the acoustic wave device according to any one of claims 1 to 10.

12. A piezoelectric substrate comprising a piezoelectric body having a first surface, wherein the piezoelectric body has an end surface located on a first side in a first direction that is a direction parallel to the first surface and connected to the first surface, and wherein in a cross section of the piezoelectric body cut along a plane parallel to the first direction and perpendicular to the first surface, a first angle formed between an extension of the first surface in the first direction and a tangent at any point on the first end surface is greater than or equal to 70° and less than 90°.

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