Acoustic wave device and communication apparatus

Abstract

To improve a frequency characteristic of an acoustic wave device.SOLUTION: An IDT electrode of an acoustic wave device, includes a first electrode finger and a second electrode finger that are adjacent to each other in a first direction, and are extended in a second direction intersecting the first direction. An intersection region of the first electrode finger and the second electrode finger contains: a first end part region and a second end part region that are opposite to each other in the second direction; and a non-end part region that is positioned between the first end part region and the second end part region. A thickness of a piezoelectric layer of the acoustic wave device is two times or less an electrode finger pitch, and a length of each of the first end part region and the second end part region in the second region is the electrode finger pitch or more and is 2.5 times or less the electrode finger pitch. In the case of consideration of a virtual cutting surface that is extended in the first direction and a thickness direction of the acoustic wave device, a cross sectional area of the first electrode finger and a cross sectional area of the second electrode finger in the first end part region, the non-end part region, and the second end part region satisfy a predetermined complementary relation.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] One aspect of the present disclosure relates to an acoustic wave device. [Background technology]

[0002] Patent Document 1 listed below discloses one configuration example of an acoustic wave device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2020 / 100949 Summary of the Invention [Problem to be solved by the invention]

[0004] It is desirable to improve the frequency characteristics of acoustic wave devices. [Means for solving the problem]

[0005] An elastic wave device according to one aspect of the present disclosure includes a piezoelectric layer and an IDT electrode located on the piezoelectric layer, the IDT electrode including first and second electrode fingers adjacent to each other in a first direction and extending in a second direction intersecting the first direction, and a first bus bar and a second bus bar opposing each other in the second direction, the first electrode fingers connected to the first bus bar and extending toward the second bus bar, the second electrode fingers connected to the second bus bar and extending toward the first bus bar, a first bus bar side, and in the acoustic wave device, an intersection region where the first electrode fingers and the second electrode fingers intersect includes, in the second direction, (i) a first end region located on the first bus bar side, (ii) a second end region located on the second bus bar side, and (iii) a non-end region located between the first end region and the second end region, and a thickness of the piezoelectric layer is equal to or less than twice the electrode finger pitch between the first electrode fingers and the second electrode fingers, and The lengths of the first and second electrode fingers are equal to or greater than the electrode finger pitch and are equal to or less than 2.5 times the electrode finger pitch. When a virtual cut plane extending in the first direction and in a thickness direction of the acoustic wave device is taken into consideration, a cross-sectional area of ​​the first electrode finger in the non-end region is referred to as a first reference cross-sectional area, and a cross-sectional area of ​​the second electrode finger in the non-end region is referred to as a second reference cross-sectional area. When the cross-sectional area of ​​the first electrode finger in the first end region is larger than the first reference cross-sectional area and the cross-sectional area of ​​the second electrode finger in the second end region is larger than the second reference cross-sectional area, If the cross-sectional area of ​​the first electrode finger in the first end region is smaller than the first reference cross-sectional area and the cross-sectional area of ​​the second electrode finger in the first end region is smaller than the second reference cross-sectional area, and the cross-sectional area of ​​the first electrode finger in the first end region is smaller than the first reference cross-sectional area and the cross-sectional area of ​​the second electrode finger in the second end region is smaller than the second reference cross-sectional area, then the cross-sectional area of ​​the first electrode finger in the second end region is larger than the first reference cross-sectional area and the cross-sectional area of ​​the second electrode finger in the first end region is larger than the second reference cross-sectional area. Effect of the Invention

[0006] According to one aspect of the present disclosure, the frequency characteristics of an elastic wave device can be improved compared to conventional devices. [Brief description of the drawings]

[0007] [Figure 1] 1 shows an example of the configuration of an acoustic wave device according to a first embodiment. [Diagram 2] 1 shows an example of the configuration of a Type 1 IDT electrode. [Diagram 3] 1 shows an example of the configuration of a Type 2 IDT electrode. [Figure 4] 1 shows an example of the configuration of a Type 3 IDT electrode. [Diagram 5] 1 shows an example of the configuration of a Type 4 IDT electrode. [Figure 6] 4 shows an example of frequency characteristics of an elastic wave device. [Figure 7] 4 shows another example of frequency characteristics of an elastic wave device. [Figure 8] 13 shows a configuration example of a Type 5 IDT electrode in the second embodiment. [Figure 9] 13 shows an example of frequency characteristics of the elastic wave device in accordance with the second embodiment. [Figure 10] 13 shows an example of the configuration of an acoustic wave device according to a third embodiment. [Figure 11] 1 shows an example of the configuration of a communication device according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [Embodiment 1] The first embodiment will be described below. For convenience of explanation, components having the same functions as those described in the first embodiment will be given the same reference numerals in the following embodiments, and the explanations will not be repeated. For simplicity, the explanations of known technical matters will be omitted as appropriate. Each component, each material, and each numerical value described in this specification are merely examples, unless there is a contradiction in the content. Therefore, unless there is a contradiction in the content, for example, the positional relationship and connection relationship of each component are not limited to the examples in each figure. In addition, each figure is not necessarily drawn to scale. In this specification, unless there is a contradiction, the notation "A to B" for two numbers A and B means "greater than or equal to A and less than or equal to B."

[0009] (One Configuration Example of Elastic Wave Device 1) FIG. 1 illustrates an example of a configuration of an elastic wave device 1 according to a first embodiment. In FIG. 1, a laminated structure of the elastic wave device 1 is illustrated in a front view. For convenience of explanation, an orthogonal coordinate system (D1-D2-D3 coordinate system) illustrated in FIG. 1 is introduced in this specification. As illustrated in FIG. 1, in the elastic wave device 1, a plurality of electrode fingers 32 may be arranged in a D1 direction. In the example of the first embodiment, the D1 direction is an arrangement direction of the electrode fingers 32 in the elastic wave device 1. The D2 direction is an example of a direction intersecting the D1 direction. The electrode fingers 32 may extend in the D2 direction. The D3 direction is a thickness direction of each portion of the elastic wave device 1. In this specification, the positive direction of the D3 direction is described as an upward direction. Therefore, the negative direction of the D3 direction is a downward direction. The D1 to D3 directions may be referred to as a first to third directions, respectively. The D1 direction may be referred to as a width direction of the elastic wave device 1, and the D2 direction may be referred to as a longitudinal direction of the elastic wave device 1.

[0010] The acoustic wave device 1 may include a piezoelectric layer 2. The piezoelectric layer 2 may include, for example, a piezoelectric single crystal material. As one example, the piezoelectric layer 2 may include lithium tantalate (also referred to as LiTaO3:LT) as a material. As another example, the piezoelectric layer 2 may include lithium niobate (also referred to as LiNbO3:LN) as a material.

[0011] The cut angles of the piezoelectric layer 2 may be expressed by Euler angles (φ, θ, ψ). As an example, when the piezoelectric layer 2 is an LT layer, φ may be -10° to 10°, θ may be 0 to 55°, and ψ may be -10° to 10°. In this way, rotated Y-cut X-propagation LT can be used as the material of the piezoelectric layer 2.

[0012] As another example, when the piezoelectric layer 2 is an LN layer, φ may be -10° to 10°, θ may be -15° to 67°, and ψ may be any angle. Alternatively, φ may be -5° to 5°, and θ may be -5° to 5°. In this way, Z-cut LN can also be used as the material for the piezoelectric layer 2.

[0013] The acoustic wave device 1 may have an IDT (Interdigital Transduce) electrode 3 located on the piezoelectric layer 2. The IDT electrode 3 excites an acoustic wave. For this reason, the IDT electrode 3 is also called an excitation electrode. The IDT electrode 3 has a plurality of electrode fingers 32. A more detailed configuration of the IDT electrode 3 will be described later.

[0014] In the first embodiment, the IDT electrode 3 is configured to excite a plate wave. Therefore, the IDT electrode 3 in the first embodiment can excite, for example, a wave in the A1 mode.

[0015] The multiple electrode fingers 32 may be alternately and repeatedly positioned on the piezoelectric layer 2 so as to have a generally constant interval in the D1 direction. In this specification, the pitch of the electrode fingers 32 is represented as p. p may be referred to as the electrode finger pitch of the IDT electrode 3. p may be, for example, the pitch (repetition interval) in the D1 direction between the centers of two adjacent electrode fingers 32. As an example, p may be set equal to half the wavelength λ (λ / 2) of the acoustic wave excited in the D1 direction by the IDT electrode 3. In this case, λ may be defined as twice the length of p. In other words, λ may be defined as 2p.

[0016] In this specification, the length of electrode finger 32 in direction D1 is referred to as width w of electrode finger 32. w may be set in accordance with p. The ratio of w to p (w / p) is also referred to as the duty of electrode finger 32. As an example, the frequency characteristics of acoustic wave device 1 can be controlled by changing the duty.

[0017] 1 indicates the thickness of the piezoelectric layer 2. In the first embodiment, the case where t is sufficiently small, that is, the piezoelectric layer 2 is sufficiently thin, is illustrated. In the first embodiment, the case where t≦λ (i.e., t≦2p) is illustrated. In this case, the IDT electrode 3 in the first embodiment can excite a wave in the A1 mode.

[0018] Acoustic wave device 1 may include a support substrate 6 that supports each component of acoustic wave device 1. Support substrate 6 is located below each component. For example, support substrate 6 may include Si as a material.

[0019] In addition, the acoustic wave device 1 may have an acoustic reflecting film 5 located between the piezoelectric layer 2 and the support substrate 6. The acoustic reflecting film 5 may be a multilayer film in which (i) low acoustic impedance layers 5a having an acoustic impedance lower than that of the piezoelectric layer 2 and (ii) high acoustic impedance layers 5b having an acoustic impedance higher than that of the low acoustic impedance layers 5a are alternately laminated.

[0020] The acoustic reflection film 5 may be a laminate unit formed by laminating one low acoustic impedance layer 5a and one high acoustic impedance layer 5b. In the example of Fig. 1, the acoustic wave device 1 includes four laminate units. An example of the material of the low acoustic impedance layer 5a is SiO2. An example of the material of the high acoustic impedance layer 5b is HfO2.

[0021] (Various configuration examples of the IDT electrode 3) 2 to 5 show various configuration examples of the IDT electrode 3. In the first embodiment, a case where the IDT electrode 3 has a uniform thickness is illustrated. FIG. 2 shows the simplest configuration example. The IDT electrode 3 in the example of FIG. 2 may be referred to as a Type 1 IDT electrode. First, the basic configuration of the IDT electrode 3 will be described with reference to FIG. 2.

[0022] In the example of Fig. 2, a first electrode finger 32a and a second electrode finger 32b are illustrated as two electrode fingers 32 in the IDT electrode 3. The second electrode finger 32b in the example of Fig. 2 is an electrode finger adjacent to the first electrode finger 32a in the direction D1. Therefore, p in the following example may be defined as the electrode finger pitch between the first electrode finger 32a and the second electrode finger 32b. For example, p may be defined as the distance between the center of the first electrode finger 32a and the center of the second electrode finger 32b in the direction D1.

[0023] The IDT electrode 3 may have a first bus bar 31a and a second bus bar 31b that face each other in the direction D2. In the example of Fig. 2, the first electrode finger 32a is connected to the first bus bar 31a. Meanwhile, the second electrode finger 32b is connected to the second bus bar 31b.

[0024] 2, the first electrode finger 32a extends from the first bus bar 31a to the second bus bar 31b. Meanwhile, the second electrode finger 32b extends from the second bus bar 31b to the first bus bar 31a. Thus, the acoustic wave device 1 has an intersection region CR where the first electrode finger 32a and the second electrode finger 32b intersect.

[0025] The intersection region CR in the example of FIG. 2 includes a first end region TB1, a second end region TB2, and a non-end region NTB. The first end region TB1 and the second end region TB2 are regions at the ends of the intersection region CR. In the D2 direction, the first end region TB1 is located on the side of the first bus bar 31a, and the second end region TB2 is located on the side of the second bus bar 31b. In this way, the first end region TB1 and the second end region TB2 face each other in the D2 direction.

[0026] The non-end region NTB is the region of the intersection region CR excluding the first end region TB1 and the second end region TB2. Therefore, the non-end region NTB is located between the first end region TB1 and the second end region TB2 in the D2 direction. The non-end region NTB may be referred to as a central region.

[0027] In the first embodiment, the D1-D3 plane (a plane extending in the D1 and D3 directions) is considered as a virtual cutting plane. Therefore, the cross-sectional area of ​​each part in the following description refers to the cross-sectional area on the virtual cutting plane unless otherwise specified.

[0028] In the type 1 IDT electrode, unlike other types of IDT electrodes described later, the cross-sectional area of ​​the electrode finger 32 is uniform throughout the intersection region CR. In this specification, the cross-sectional area of ​​the first electrode finger 32a in the non-end region NTB is referred to as the first reference cross-sectional area, and the cross-sectional area of ​​the second electrode finger 32b in the non-end region NTB is referred to as the second reference cross-sectional area. In this specification, the first reference cross-sectional area is denoted as S1(NTB), and the second reference cross-sectional area is denoted as S2(NTB). In the first embodiment, for the sake of clarity, a case is illustrated in which the dimensions of each part in each of the multiple electrode fingers are designed to be the same. Therefore, in the example of the first embodiment, S1(NTB) and S2(NTB) are the same value S_standard. As described above, the cross-sectional area of ​​the electrode finger 32 in the example of FIG. 2 is equal to S_standard throughout the intersection region CR.

[0029] Therefore, the width of the electrode fingers 32 in the example of FIG. 2 is uniform throughout the entire intersection region CR. In this specification, the width of the first electrode finger 32a in the non-end region NTB is referred to as the first reference width, and the width of the second electrode finger 32b in the non-end region NTB is referred to as the second reference width. In this specification, the first reference width is denoted as w1(NTB), and the second reference width is denoted as w2(NTB). In the example of embodiment 1, w1(NTB) and w2(NTB) are the same value w_standard. As described above, the width of the electrode fingers 32 in the example of FIG. 2 is equal to w_standard throughout the entire intersection region CR.

[0030] As is clear from the above description of the width of the type 1 IDT electrode, the duty of the electrode finger 32 in the example of FIG. 2 is uniform throughout the entire intersection region CR. In this specification, the duty of the first electrode finger 32a in the non-end region NTB is referred to as the first reference duty, and the duty of the second electrode finger 32b in the non-end region NTB is referred to as the second reference duty. In this specification, the first reference duty is represented as Duty1(NTB), and the second reference duty is represented as Duty2(NTB). In the example of embodiment 1, Duty1(NTB) and Duty2(NTB) are the same value, Duty_standard. As described above, the duty of the electrode finger 32 in the example of FIG. 2 is equal to Duty_standard throughout the entire intersection region CR.

[0031] 2 indicates the length of the first end region TB1 in the direction D2. The second electrode finger 32b in FIG. 2 extends beyond the second end region TB2 and the non-end region NTB to the first end region TB1. Thus, the tip position of the second electrode finger 32b may be defined as the end position of the first end region TB1 on the first bus bar 31a side. The first end region TB1 may extend from the end position to the second bus bar 31b side by a predetermined length (e.g., p to 2.5p). Therefore, L1 may be p to 2.5p.

[0032] 2 indicates the length of the second end region TB2 in the direction D2. The first electrode finger 32a in FIG. 2 extends beyond the first end region TB1 and the non-end region NTB to the second end region TB2. Thus, the tip position of the first electrode finger 32a may be defined as the end position of the second end region TB2 on the second bus bar 31b side. The second end region TB2 may extend from the end position to the first bus bar 31a side by a predetermined length (e.g., p to 2.5p). In this manner, L2 may also be p to 2.5p.

[0033] The dimension L0 in FIG. 2 represents the length of the non-end region NTB in the D2 direction. The total length of the intersection region CR in the D2 direction is also referred to as the intersection region length. The intersection region length can be expressed as L0+L1+L2. In the example of FIG. 2, L1=L2. However, L1=L2 does not necessarily have to be the case. L1 and L2 may be different.

[0034] As shown in Fig. 2, IDT electrode 3 may have a plurality of dummy electrode fingers extending in direction D2. The dummy electrode fingers enable more precise control of the frequency characteristics of acoustic wave device 1. Fig. 2 shows first dummy electrode finger 35a and second dummy electrode finger 35b as examples of the dummy electrode fingers. The pitch of the dummy electrode fingers may be set to a value equal to the pitch of electrode fingers 32. Therefore, the dummy electrode fingers may face electrode fingers 32 across a gap in direction D2.

[0035] In the example of FIG. 2, the first dummy electrode finger 35a is connected to the first bus bar 31a. The first dummy electrode finger 35a extends from the first bus bar 31a toward the second bus bar 31b. Therefore, the first dummy electrode finger 35a faces the second electrode finger 32b in the direction D2. On the other hand, the second dummy electrode finger 35b is connected to the second bus bar 31b. The second dummy electrode finger 35b extends from the second bus bar 31b toward the first bus bar 31a. Therefore, the second dummy electrode finger 35b faces the first electrode finger 32a in the direction D2.

[0036] Next, another configuration example of the IDT electrode 3 will be described with reference to FIG. 3. The IDT electrode 3 in the example of FIG. 3 may be referred to as a type 2 IDT electrode. In the type 2 IDT electrode, the cross-sectional area of ​​the first electrode finger 32a in the first end region TB1 is set to be larger than S1(NTB). On the other hand, the cross-sectional area of ​​the first electrode finger 32a in the second end region TB2 is set to be equal to S1(NTB). In this specification, the cross-sectional area of ​​the first electrode finger 32a in the first end region TB1 is denoted as S1(TB1), and the cross-sectional area of ​​the first electrode finger 32a in the second end region TB2 is denoted as S1(TB2). As described above, in the example of FIG. 3, S1(TB1)>S1(NTB)=S1(TB2).

[0037] For this reason, the first electrode finger 32a in the example of Fig. 3 includes a first normal portion 321a and a first wide portion 322a. The first wide portion 322a is located on the base side of the first electrode finger 32a. Therefore, the first wide portion 322a is located closer to the first bus bar 31a than the first normal portion 321a. The first wide portion 322a in the example of Fig. 3 is located in the first end region TB1.

[0038] 3, the first normal portion 321a is a portion of the first electrode finger 32a excluding the first wide portion 322a. Therefore, the first normal portion 321a is located closer to the second bus bar 31b than the first wide portion 322a. The first normal portion 321a in the example of FIG. 3 is located across the non-end portion NTB and the second end portion portion TB2.

[0039] As shown in Fig. 3, the width of the first wide portion 322a is wider than the width of the first normal portion 321a. In this specification, the width of the first electrode finger 32a in the first end region TB1 is denoted as w1(TB1), and the width of the first electrode finger 32a in the second end region TB2 is denoted as w1(TB2). In the example of Fig. 3, w1(TB1)>w1(NTB)=w1(TB2).

[0040] Therefore, the duty of the first wide portion 322a is larger than the duty of the first normal portion 321a. In this specification, the duty of the first electrode finger 32a in the first end region TB1 is denoted as Duty1 (TB1), and the duty of the first electrode finger 32a in the second end region TB2 is denoted as Duty1 (TB2). In the example of FIG. 3, Duty1 (TB1)>Duty1 (NTB)=Duty1 (TB2).

[0041] In the type 2 IDT electrode, the second electrode finger 32b is configured to form a pair with the first electrode finger 32a. Therefore, in the type 2 IDT electrode, the cross-sectional area of ​​the second electrode finger 32b in the second end region TB2 is set to be larger than S2(NTB). On the other hand, the cross-sectional area of ​​the second electrode finger 32b in the first end region TB1 is set to be equal to S2(NTB). In this specification, the cross-sectional area of ​​the second electrode finger 32b in the first end region TB1 is denoted as S2(TB1), and the cross-sectional area of ​​the second electrode finger 32b in the second end region TB2 is denoted as S2(TB2). As described above, in the example of FIG. 3, S2(TB1)=S2(NTB) <S2(TB2)である。

[0042] For this reason, the second electrode finger 32b in the example of Fig. 3 includes a second normal portion 321b and a second wide portion 322b. The second wide portion 322b is located on the base side of the second electrode finger 32b. Therefore, the second wide portion 322b is located closer to the second bus bar 31b than the second normal portion 321b. The second wide portion 322b in the example of Fig. 3 is located in the second end region TB2.

[0043] 3, the second normal portion 321b is a portion of the second electrode finger 32b excluding the second wide portion 322b. Therefore, the second normal portion 321b is located closer to the first bus bar 31a than the second wide portion 322b. The second normal portion 321b in the example of FIG. 3 is located across the non-end portion NTB and the first end portion portion TB1.

[0044] 3, the width of the second wide portion 322b is wider than the width of the second normal portion 321b. In this specification, the width of the second electrode finger 32b in the first end region TB1 is denoted as w2(TB1), and the width of the second electrode finger 32b in the second end region TB2 is denoted as w2(TB2). In the example of FIG. 3, w2(TB1)=w2(NTB). <w2(TB2)である。

[0045] Therefore, the duty of the second wide portion 322b is larger than the duty of the second normal portion 321b. In this specification, the duty of the second electrode finger 32b in the first end region TB1 is represented as Duty2(TB1), and the duty of the second electrode finger 32b in the second end region TB2 is represented as Duty2(TB2). In the example of FIG. 3, Duty2(TB1)=Duty2(NTB). <Duty2(TB2)である。

[0046] In this specification, the first normal portion 321a and the second normal portion 321b are collectively referred to as a normal portion 321, and the first wide portion 322a and the second wide portion 322b are collectively referred to as a wide portion 322. In the example of FIG. S1(TB1)=S2(TB2)=S_large w1(TB1)=w2(TB2)=w_large Duty1(TB1)=Duty2(TB2)=Duty_large The wide portion 322 is designed so that S_large is larger than S_standard. w_large is larger than w_standard. Duty_large is larger than Duty_standard.

[0047] Next, another configuration example of the IDT electrode 3 will be described with reference to Fig. 4. The IDT electrode 3 in the example of Fig. 4 may be referred to as a Type 3 IDT electrode. In the Type 3 IDT electrode, unlike the Type 2 IDT electrode, S1(TB2) is set to be smaller than S1(NTB). That is, in the example of Fig. 4, unlike the example of Fig. 3, S1(TB1)>S1(NTB)>S1(TB2).

[0048] For this reason, the first electrode finger 32a in the example of Fig. 4 further includes a first narrow portion 323a located in the second end region TB2. The first normal portion 321a in the example of Fig. 4 is a portion of the first electrode finger 32a excluding the first wide portion 322a and the first narrow portion 323a. Therefore, the first normal portion 321a in Fig. 4 is located in the non-end region NTB.

[0049] As shown in Fig. 4, the width of the first narrow portion 323a is narrower than the width of the first normal portion 321a. Therefore, in the example of Fig. 4, unlike the example of Fig. 3, w1(TB1)>w1(NTB)>w1(TB2).

[0050] For this reason, the duty of the first narrow width portion 323a is smaller than the duty of the first normal portion 321a. Therefore, in the example of Fig. 4, unlike the example of Fig. 3, Duty1(TB1)>Duty1(NTB)>Duty1(TB2).

[0051] Next, the second electrode finger 32b in the IDT electrode of type 3 will be described. In the IDT electrode of type 3, unlike the IDT electrode of type 2, S2(TB1) is set smaller than S2(NTB). That is, in the example of FIG. 4, unlike the example of FIG. 3, S2(TB1) <S2(NTB)<S2(TB2)である。

[0052] For this reason, the second electrode finger 32b in the example of Fig. 4 further includes a second narrow portion 323b located in the first end region TB1. The second normal portion 321b in the example of Fig. 4 is a portion of the second electrode finger 32b excluding the second wide portion 322b and the second narrow portion 323b. Therefore, the second normal portion 321b in Fig. 4 is located in the non-end region NTB.

[0053] As shown in Fig. 4, the width of the second narrow portion 323b is narrower than the width of the second normal portion 321b. Therefore, in the example of Fig. 4, unlike the example of Fig. 3, w2(TB1) <w2(NTB)<w2(TB2)である。

[0054] Therefore, the duty of the second narrow portion 323b is smaller than the duty of the second normal portion 321b. Thus, in the example of FIG. 4, unlike the example of FIG. 3, Duty2(TB1) < Duty2(NTB) < Duty2(TB2).

[0055] In this specification, the first narrow portion 323a and the second narrow portion 323b are collectively referred to as the narrow portion 323. In the example of FIG. 4, S1(TB2) = S2(TB1) = S_small w1(TB2) = w2(TB1) = w_small Duty1(TB2) = Duty2(TB1) = Duty_small as shown, the narrow portion 323 is designed. S_small may be a value smaller than S_standard. w_small may be a value smaller than w_standard. Duty_small may be a value smaller than Duty_standard.

[0056] Next, with reference to FIG. 5, yet another configuration example of the IDT electrode 3 will be described. The IDT electrode 3 in the example of FIG. 5 may be referred to as a type 4 IDT electrode. The type 4 IDT electrode has a configuration that is paired with the type 3 IDT electrode.

[0057] Specifically, in the type 4 IDT electrode, S1(TB1) is set smaller than S1(NTB), and S1(TB2) is set larger than S1(NTB). That is, in the example of FIG. 5, S1(TB1) < S1(NTB) < S1(TB2).

[0058] From this, in the example of FIG. 5, the first narrow portion 323a is located in the first end region TB1, and the first wide portion 322a is located in the second end region TB2. Thus, in the example of FIG. 5, w1(TB1) < w1(NTB) < w1(TB2). Therefore, in the example of FIG. 5, Duty1(TB1) < Duty1(NTB) < Duty1(TB2).

[0059] In the type 4 IDT electrode, S2(TB1) is set to be larger than S2(NTB) and S2(TB2) is set to be smaller than S2(NTB). That is, in the example of FIG. 5, S2(TB1)>S2(NTB)>S2(TB2).

[0060] For this reason, in the example of Fig. 5, the second narrow portion 323b is located in the second end region TB2, and the second wide portion 322b is located in the first end region TB1. Therefore, in the example of Fig. 5, w2(TB1)>w2(NTB)>w2(TB2). Therefore, in the example of Fig. 5, Duty2(TB1)>Duty1(NTB)>Duty1(TB2).

[0061] As is clear from the above explanations, the example of FIG. 5 is different from the example of FIG. S1(TB2)=S2(TB1)=S_large w1(TB2)=w2(TB1)=w_large Duty1(TB2)=Duty2(TB1)=Duty_large and S1(TB1)=S2(TB2)=S_small w1(TB1)=w2(TB2)=w_small Duty1(TB1)=Duty2(TB2)=Duty_small It is.

[0062] (Study on frequency characteristics of elastic wave device 1) The frequency characteristics of acoustic wave device 1 generally depend on the design of IDT electrode 3. Therefore, the inventors of the present application (hereinafter abbreviated as “the inventors”) conducted simulations to derive the frequency characteristics of acoustic wave device 1 for each of Types 1 to 4 described above.

[0063] Fig. 6 shows an example of frequency characteristics derived by the inventors. Specifically, Fig. 6 shows phase characteristics of elastic wave devices 1 for each of Types 1, 2, and 3. The horizontal axis of the graph in Fig. 6 represents frequency, and the vertical axis represents phase.

[0064] 6, the settings are Duty_small=0.4, Duty_standard=0.5, and Duty_large=0.6. Therefore, the average value of Duty_small and Duty_large is equal to Duty_standard.

[0065] As is clear from this, for example, Duty_small=Duty_standard-ΔDuty Duty_large=Duty_standard+ΔDuty Duty_small and Duty_large corresponding to Duty_standard may be set as follows. ΔDuty may be a positive number smaller than Duty_standard. When Duty_small and Duty_large are set in this way, the average value of Duty_small and Duty_large becomes equal to Duty_standard. In the example of FIG. 6, ΔDuty=0.1.

[0066] From the above, for example, w_small=w_standard-Δw w_large=w_standard+Δw w_small and w_large corresponding to w_standard may be set as Δw. Δw may be any positive number smaller than w_standard. When w_small and w_large are set in this way, the average value of w_small and w_large becomes equal to w_standard.

[0067] Also, S_small=S_standard-ΔS S_large=S_standard+ΔS It is also possible to set S_small and S_large corresponding to S_standard as follows. ΔS may be any positive number smaller than S_standard. When S_small and S_large are set in this way, the average value of S_small and S_large becomes equal to S_standard.

[0068] Referring again to FIG. 6, the graph 610 in FIG. 6 shows frequency characteristics in a frequency range including the resonant frequency and anti-resonant frequency of the elastic wave device 1. The graph 620 shows an enlarged view of the low-frequency region in the frequency range (e.g., the region including the resonant frequency), the graph 630 shows an enlarged view of the central region in the frequency range, and the graph 640 shows an enlarged view of the high-frequency region in the frequency range (e.g., the region including the anti-resonant frequency). As shown in FIG. 6, it was confirmed that Type 3 provides better frequency characteristics than Types 1 and 2. For example, as shown in the graphs 620 and 630, Type 3 effectively reduces spurious signals that may occur in Type 2.

[0069] FIG. 7 shows another example of frequency characteristics derived by the inventors. Specifically, FIG. 7 shows phase characteristics of elastic wave device 1 for each of Type 1, Type 2, and Type 4. FIG. 7 is a diagram paired with FIG. 6. In the example of FIG. 7, Duty_small=0.4, Duty_standard=0.5, and Duty_large=0.6 are also set. As shown in FIG. 7, it was confirmed that Type 4 also provides better frequency characteristics than Types 1 and 2. For example, as shown in the graphs denoted by reference numerals 720 and 730, Type 4 also effectively reduces spurious signals that may occur in Type 2.

[0070] As described above, Types 3 and 4 can achieve frequency characteristics of acoustic wave devices that are better than those of conventional devices. In this manner, for example, by designing first electrode fingers 32a so that the difference between S1(TB1) and S1(NTB) is compensated for by the difference between S1(TB2) and S1(NTB), the frequency characteristics of acoustic wave device 1 can be improved. In other words, by designing first electrode fingers 32a so that the average value of S1(TB1) and S1(TB2) is as close as possible to S1(NTB), the frequency characteristics of acoustic wave device 1 can be improved. The same applies to the design of second electrode fingers 32b.

[0071] (Additional information about types 3 and 4) As shown in the above-mentioned Fig. 4 and Fig. 5, the first electrode finger 32a and the second electrode finger 32b in the type 3 and type 4 have complementary shapes in the first end region TB1. For this reason, for example, |S1(TB1)-S1(NTB)|, which is the absolute value of the difference between S1(TB1) and S1(NTB), may be set to a value approximately equal to |S2(TB1)-S2(NTB)|, which is the absolute value of the difference between S2(TB1) and S2(NTB). As an example, |S1(TB1)-S1(NTB)| may be 0.75 to 1.25 times |S2(TB1)-S2(NTB)|. Alternatively, |S1(TB1)-S1(NTB)| may be 0.9 to 1.1 times |S2(TB1)-S2(NTB)|.

[0072] The first electrode finger 32a and the second electrode finger 32b in types 3 and 4 have complementary shapes in the second end region TB2 as well. Therefore, |S1(TB2)-S1(NTB)|, which is the absolute value of the difference between S1(TB2) and S1(NTB), may be set to a value approximately equal to |S2(TB2)-S2(NTB)|, which is the absolute value of the difference between S2(TB2) and S2(NTB). For example, |S1(TB2)-S1(NTB)| may be 0.75 to 1.25 times |S2(TB2)-S2(NTB)|. Alternatively, |S1(TB2)-S1(NTB)| may be 0.9 to 1.1 times |S2(TB2)-S2(NTB)|.

[0073] In the electrode fingers 32 of types 3 and 4, the shape of the portion belonging to the first end region TB1 and the shape of the portion belonging to the second end region TB2 are complementary to each other. For this reason, |S1(TB1)-S1(NTB)| may be set to a value substantially equal to |S2(TB2)-S2(NTB)|. For example, |S1(TB1)-S1(NTB)| may be 0.75 to 1.25 times |S2(TB2)-S2(NTB)|. Alternatively, |S1(TB1)-S1(NTB)| may be 0.9 to 1.1 times |S2(TB2)-S2(NTB)|.

[0074] In addition, in Type 3 and Type 4, |S1(TB2)-S1(NTB)| may be set to a value approximately equal to |S2(TB1)-S2(NTB)|. For example, |S1(TB2)-S1(NTB)| may be 0.75 to 1.25 times |S2(TB1)-S2(NTB)|. Alternatively, |S1(TB2)-S1(NTB)| may be 0.9 to 1.1 times |S2(TB1)-S2(NTB)|.

[0075] As can be understood from the above explanations, Duty1 (TB1) and Duty1 (TB2) may be set to values ​​approximately equal to Duty1 (NTB). For example, Duty1 (TB1) and Duty1 (TB2) may be 0.75 to 1.25 times Duty1 (NTB). Alternatively, Duty1 (TB1) and Duty1 (TB2) may be 0.9 to 1.1 times Duty1 (NTB).

[0076] In addition, Duty2(TB1) and Duty2(TB2) may be set to values ​​approximately equal to Duty2(NTB). For example, Duty2(TB1) and Duty2(TB2) may be 0.75 to 1.25 times Duty2(NTB). Alternatively, Duty2(TB1) and Duty2(TB2) may be 0.9 to 1.1 times Duty2(NTB).

[0077] Therefore, as an example, in Type 3, Duty1 (TB1) may be set to be larger than Duty1 (NTB) and 1.25 times or less than Duty1 (NTB). In this case, Duty1 (TB2) may be set to be 0.75 times or more than Duty1 (NTB) and smaller than Duty1 (NTB).

[0078] In Type 3, Duty2(TB1) may be set to be 0.75 times or more and smaller than Duty2(NTB). In this case, Duty2(TB2) may be set to be larger than Duty2(NTB) and 1.25 times or less than Duty2(NTB).

[0079] On the other hand, in Type 4, Duty1 (TB1) may be set to be 0.75 times or more and smaller than Duty1 (NTB). In this case, Duty1 (TB2) may be set to be larger than Duty1 (NTB) and 1.25 times or less than Duty1 (NTB).

[0080] In Type 4, Duty2(TB1) may be set to be greater than Duty2(NTB) and equal to or less than 1.25 times Duty2(NTB). In this case, Duty2(TB2) may be set to be greater than 0.75 times Duty2(NTB) and equal to or less than Duty2(NTB).

[0081] In this specification, the cross-sectional area of ​​the first dummy electrode finger 35a is denoted as S1_DUM, and the cross-sectional area of ​​the second dummy electrode finger 35b is denoted as S2_DUM. In Type 3 and Type 4, S1(TB1) may be set to a value approximately equal to S1_DUM. Also, S2(TB2) may be set to a value approximately equal to S2_DUM. For example, S1(TB1) may be 0.75 to 1.25 times S1_DUM, and S2(TB2) may be 0.75 to 1.25 times S2_DUM. Alternatively, S1(TB1) may be 0.9 to 1.1 times S1_DUM, and S2(TB2) may be 0.9 to 1.1 times S2_DUM.

[0082] [Embodiment 2] FIG. 8 shows a configuration example of the IDT electrode 3 in the second embodiment. Unlike the first embodiment, the second embodiment illustrates a case where the IDT electrode 3 has a non-uniform thickness. The IDT electrode 3 in the example of FIG. 8 may be referred to as a Type 5 IDT electrode. The example of FIG. 8 illustrates a case where S1(TB1)>S1(NTB)>S1(TB2), as in the example of FIG. 4 described above. Therefore, Type 5 is a configuration that is paired with Type 3 in the example of FIG. 4 described above.

[0083] The first electrode finger 32a in the example of Fig. 8 has a first thin portion 326a instead of the first narrow portion 323a in the example of Fig. 4. Therefore, the first thin portion 326a in the example of Fig. 8 is located in the second end region TB2. In the example of Fig. 8, the thickness of the first thin portion 326a is smaller than the thickness of the first normal portion 321a. On the other hand, the width of the first thin portion 326a is equal to the width of the first normal portion 321a.

[0084] In this specification, the thickness of the first electrode finger 32a in the non-end region NTB is referred to as the first reference thickness. The first reference thickness is denoted as t1(NTB). In addition, in this specification, the thickness of the first electrode finger 32a in the first end region TB1 is denoted as t1(TB1), and the thickness of the first electrode finger 32a in the second end region TB2 is denoted as t1(TB2).

[0085] In the example of Figure 8, w1(TB1)>w1(NTB)≧w1(TB2), and t1(TB1) ≧ t1(NTB) > t1(TB2) It is only necessary that the width and thickness of each portion of first electrode finger 32a be set so that the relationship S1(TB1)>S1(NTB)>S1(TB2) is satisfied by designing first electrode finger 32a in this manner.

[0086] Next, the second electrode finger 32b in the example of FIG. 8 will be described. In the example of FIG. 8, similar to the example of FIG. 4 described above, S2(TB1) < S2(NTB) < S1(TB2). Therefore, the second electrode finger 32b in the example of FIG. 8 has a second thin portion 326b instead of the second narrow portion 323b in the example of FIG. 4. The second thin portion 326b in the example of FIG. 8 is located in the second end region TB2. In the example of FIG. 8, the thickness of the second thin portion 326b is smaller than the thickness of the second normal portion 321b. On the other hand, the width of the second thin portion 326b is equal to the width of the second normal portion 321b.

[0087] In this specification, the thickness of the second electrode finger 32b in the non-end region NTB is referred to as the second reference thickness. And the second reference thickness is denoted as t2(NTB). Also, in this specification, the thickness of the second electrode finger 32b in the first end region TB1 is denoted as t2(TB1), and the thickness of the second electrode finger 32b in the second end region TB2 is denoted as t2(TB2).

[0088] In the example of FIG. 8, w2(TB1) ≦ w2(NTB) < w1(TB2), and t2(TB1) < t2(NTB) ≦ t2(TB2) as long as the width and thickness of each part of the second electrode finger 32b are set like this. By designing the second electrode finger 32b in this way, the relationship of S2(TB1) < S2(NTB) < S1(TB2) is satisfied.

[0089] In the example of FIG. 8, t1(NTB) and t2(NTB) are the same value t_standard. In this specification, the first thin portion 326a and the second thin portion 326b are collectively referred to as the thin portion 326. In the example of FIG. 8, w1(TB2) = w2(TB1) = w_standard t1(TB2) = t2(TB1) = t_small as long as the thin portion 326 is designed like this. t_small may be a value smaller than t_standard.

[0090] On the other hand, in the example of FIG. 8, w1(TB1)=w2(TB2)=w_large t1(TB1)=t2(TB2)=t_standard The wide portion 322 is designed so that

[0091] As is clear from the description of the first embodiment, in the example of Fig. 8 as well, the electrode fingers 32 may be designed so that the average value of S_small and S_large is equal to S_standard. S_small+S_large=2 S_standard The following relationship holds.

[0092] And in the example in Figure 8, S_small =w_standard·t_small S_standard=w_standard·t_standard S_large = w_large t_standard It can be expressed as:

[0093] For this reason, in the example in Figure 8, w_standard·t_small+w_large·t_standard =2 w_standard t_standard The electrode fingers 32 may be designed so that the following relationship holds:

[0094] Therefore, t_small in the example of Figure 8 is t_small =(2·S_standard-S_large) / w_standard It may be defined as:

[0095] (Further Consideration of Frequency Characteristics of Elastic Wave Device 1) The inventors also derived the frequency characteristics of the elastic wave device 1 by simulation for Type 5. FIG. 9 shows an example of the frequency characteristics derived by the inventors. FIG. 9 is a figure paired with FIG. 6 described above. In FIG. 9, the phase characteristics of the elastic wave device 1 are shown for each of Type 1 and Type 5.

[0096] As shown in FIG. 9, it was confirmed that for Type 5, better frequency characteristics can be obtained compared to Type 1. As described above, even with Type 5, it is possible to realize frequency characteristics of an elastic wave device that are superior to those of the prior art. Thus, by partially changing the thickness of the electrode fingers 32 to change the cross-sectional area of the electrode fingers 32, the frequency characteristics of the elastic wave device 1 can also be improved.

[0097] (Another configuration example of Embodiment 2) As can be understood from the correspondence relationship with the example of FIG. 5 described above, in another configuration example of Embodiment 2, it may be set that S1(TB1) < S1(NTB) < S1(TB2). In this case, w1(TB1) ≤ w1(NTB) < w1(TB2), and t1(TB1) < t1(NTB) ≤ t1(TB2) it is sufficient that the width and thickness of each part of the first electrode finger 32a are set as described above. By designing the first electrode finger 32a in this way, the relationship of S1(TB1) < S1(NTB) < S1(TB2) is satisfied.

[0098] Therefore, in this another configuration example, it is sufficient that S2(TB1) > S1(NTB) > S1(TB2) is set. In this case, w2(TB1) > w2(NTB) ≥ w2(TB2), and t2(TB1) ≥ t2(NTB) > t2(TB2) it is sufficient that the width and thickness of each part of the second electrode finger 32b are set as described above. By designing the second electrode finger 32b in this way, the relationship of S2(TB1) > S2(NTB) > S2(TB2) is satisfied.

[0099] As is clear from the above explanations, in this another configuration example, w1(TB2)=w2(TB1)=w_large t1(TB2)=t2(TB1)=t_standard w1(TB1)=w2(TB2)=w_standard t1(TB1)=t2(TB2)=t_small The electrode fingers 32 may be designed so that:

[0100] (Supplementary Note on the Second Embodiment) The increase in thickness of the electrode finger 32 may be achieved by an additional film. Thus, at least one of the first electrode finger 32a and the second electrode finger 32b may have an additional film. As an example, the additional film may be a dielectric film. As another example, the additional film may be a so-called mass additional film.

[0101] The thickness of the electrode finger in this specification may be defined as the thickness of the portion including the additional film. Therefore, the cross-sectional area of ​​the electrode finger in this specification may be defined as the cross-sectional area of ​​the portion including the additional film. For this reason, for example, the thin portion 326 in the example of FIG. 8 may be a portion of the electrode finger 32 where the additional film is not present. In this case, the normal portion 321 and the wide portion 322 may be portions where the additional film is present.

[0102] [Embodiment 3] FIG. 10 shows an example of the configuration of an elastic wave device 1V according to a third embodiment. FIG. 10 is a paired view with FIG. 1. Elastic wave device 1V is an example of a membrane-type elastic wave device. As shown in FIG. 10, elastic wave device 1V may include a membrane structure having a hollow portion MA surrounded by a piezoelectric layer 2 and a support substrate 6. Unlike the elastic wave device 1 in FIG. 1, elastic wave device 1V may not have an acoustic reflection film 5.

[0103] The IDT electrode 3 in the acoustic wave device 1V may be configured to excite, for example, a bulk wave. As an example, the IDT electrode 3 in the acoustic wave device 1V may excite a bulk wave in a thickness shear mode that propagates in the D3 direction.

[0104] As described above, an acoustic wave device according to an embodiment of the present disclosure may be a membrane-type acoustic wave device. Therefore, for example, an IDT electrode according to an embodiment of the present disclosure may be configured to excite a plate wave or a bulk wave.

[0105] [Embodiment 4] FIG. 11 illustrates an example of a configuration of a communication device 151 according to the fourth embodiment. The communication device 151 performs wireless communication using radio waves. The communication device 151 may include an acoustic wave device according to an aspect of the present disclosure (e.g., the acoustic wave device 1). For example, the communication device 151 may include an acoustic wave filter 100 having the acoustic wave device. Both a transmission filter 109T and a reception filter 111R in FIG. 11 are examples of the acoustic wave filter 100.

[0106] In the communication device 151, a transmission information signal TIS including information to be transmitted may be modulated and frequency-raised (converted into a high-frequency signal having a carrier frequency) by an RF-IC (Radio Frequency-Integrated Circuit) 153, and converted into a transmission signal TS. A band-pass filter 155 may remove unnecessary components from the TS other than the transmission passband. Next, the TS after removing the unnecessary components may be amplified by an amplifier 157, and then input to a transmission filter 109T.

[0107] The transmission filter 109T may remove unnecessary components other than the transmission passband from the transmission signal TS input via the transmission terminal. The transmission filter 109T may output the TS after removing the unnecessary components to the antenna 159 via the antenna terminal ANT. The antenna 159 may convert the TS, which is an electrical signal input to itself, into radio waves as a wireless signal and transmit the radio waves to the outside of the communication device 151.

[0108] Furthermore, the antenna 159 may convert the received radio wave from the outside into a reception signal RS, which is an electric signal. The antenna 159 may input the RS to the reception filter 111R via the antenna terminal ANT. The reception filter 111R may remove unnecessary components other than the reception passband from the input RS. The reception filter 111R may output the reception signal RS after the unnecessary components have been removed to the amplifier 161 via the reception terminal. The output RS may be amplified by the amplifier 161. The bandpass filter 163 may remove unnecessary components other than the reception passband from the amplified RS. The RS after the unnecessary components have been removed may be frequency-downgraded and demodulated by the RF-IC 153, and converted into a reception information signal RIS.

[0109] The TIS and RIS may be low-frequency signals (baseband signals) containing appropriate information. For example, the TIS and RIS may be analog voice signals or digitized voice signals. The passband of the wireless signals may be set appropriately and may conform to various known standards.

[0110] 〔summary〕 An elastic wave device according to a first aspect of the present disclosure includes a piezoelectric layer and an IDT electrode located on the piezoelectric layer. The IDT electrode includes first and second electrode fingers adjacent to each other in a first direction and extending in a second direction intersecting the first direction, and a first bus bar and a second bus bar opposing each other in the second direction, the first electrode fingers being connected to the first bus bar and extending toward the second bus bar, and the second electrode fingers being connected to the second bus bar and extending toward the first bus bar. a first bus bar side, and in the acoustic wave device, an intersection region where the first electrode fingers and the second electrode fingers intersect includes, in the second direction, (i) a first end region located on the first bus bar side, (ii) a second end region located on the second bus bar side, and (iii) a non-end region located between the first end region and the second end region, and a thickness of the piezoelectric layer is equal to or less than twice the electrode finger pitch between the first electrode fingers and the second electrode fingers, and The lengths of the first and second electrode fingers are equal to or greater than the electrode finger pitch and are equal to or less than 2.5 times the electrode finger pitch. When a virtual cut plane extending in the first direction and in a thickness direction of the acoustic wave device is taken into consideration, a cross-sectional area of ​​the first electrode finger in the non-end region is referred to as a first reference cross-sectional area, and a cross-sectional area of ​​the second electrode finger in the non-end region is referred to as a second reference cross-sectional area. When the cross-sectional area of ​​the first electrode finger in the first end region is larger than the first reference cross-sectional area and the cross-sectional area of ​​the second electrode finger in the second end region is larger than the second reference cross-sectional area, If the cross-sectional area of ​​the first electrode finger in the first end region is smaller than the first reference cross-sectional area and the cross-sectional area of ​​the second electrode finger in the first end region is smaller than the second reference cross-sectional area, and the cross-sectional area of ​​the first electrode finger in the first end region is smaller than the first reference cross-sectional area and the cross-sectional area of ​​the second electrode finger in the second end region is smaller than the second reference cross-sectional area, then the cross-sectional area of ​​the first electrode finger in the second end region is larger than the first reference cross-sectional area and the cross-sectional area of ​​the second electrode finger in the first end region is larger than the second reference cross-sectional area.

[0111] In an elastic wave device according to aspect 2 of the present disclosure, in aspect 1, the absolute value of the difference between the cross-sectional area of ​​the first electrode finger in the first end region and the first reference cross-sectional area may be 0.75 times or more and 1.25 times or less of the absolute value of the difference between the cross-sectional area of ​​the second electrode finger in the first end region and the second reference cross-sectional area.

[0112] In an elastic wave device according to aspect 3 of the present disclosure, in aspect 1 or 2, the absolute value of the difference between the cross-sectional area of ​​the first electrode finger in the second end region and the first reference cross-sectional area may be 0.75 times or more and 1.25 times or less of the absolute value of the difference between the cross-sectional area of ​​the second electrode finger in the second end region and the second reference cross-sectional area.

[0113] In an elastic wave device according to aspect 4 of the present disclosure, in any one of aspects 1 to 3, the absolute value of the difference between the cross-sectional area of ​​the first electrode finger in the first end region and the first reference cross-sectional area may be 0.75 times or more and 1.25 times or less of the absolute value of the difference between the cross-sectional area of ​​the second electrode finger in the second end region and the second reference cross-sectional area.

[0114] In an elastic wave device according to aspect 5 of the present disclosure, in any one of aspects 1 to 4, the absolute value of the difference between the cross-sectional area of ​​the first electrode finger in the second end region and the first reference cross-sectional area may be 0.75 times or more and 1.25 times or less of the absolute value of the difference between the cross-sectional area of ​​the second electrode finger in the first end region and the second reference cross-sectional area.

[0115] In an elastic wave device according to aspect 6 of the present disclosure, in any one of aspects 1 to 5, the cross-sectional area of ​​the first electrode finger in the first end region may be larger than the first reference cross-sectional area, the cross-sectional area of ​​the first electrode finger in the second end region may be smaller than the first reference cross-sectional area, the cross-sectional area of ​​the second electrode finger in the second end region may be larger than the second reference cross-sectional area, and the cross-sectional area of ​​the second electrode finger in the first end region may be smaller than the second reference cross-sectional area.

[0116] In an elastic wave device according to aspect 7 of the present disclosure, in any one of aspects 1 to 5, the cross-sectional area of ​​the first electrode finger in the first end region may be smaller than the first reference cross-sectional area, the cross-sectional area of ​​the first electrode finger in the second end region may be larger than the first reference cross-sectional area, the cross-sectional area of ​​the second electrode finger in the second end region may be smaller than the second reference cross-sectional area, and the cross-sectional area of ​​the second electrode finger in the first end region may be larger than the second reference cross-sectional area.

[0117] In an elastic wave device according to aspect 8 of the present disclosure, in any one of aspects 1 to 7, the length of the first electrode finger in the first direction in the non-end region is referred to as a first reference width, and the length of the second electrode finger in the non-end region in the first direction is referred to as a second reference width, and when the width of the first electrode finger in the first end region is longer than the first reference width and the width of the second electrode finger in the second end region is longer than the second reference width, the width of the first electrode finger in the second end region may be shorter than the first reference width and the width of the second electrode finger in the first end region may be shorter than the second reference width; and when the width of the first electrode finger in the first end region is shorter than the first reference width and the width of the second electrode finger in the second end region is shorter than the second reference width, the width of the first electrode finger in the second end region may be longer than the first reference width and the width of the second electrode finger in the first end region may be longer than the second reference width.

[0118] In an elastic wave device according to a ninth aspect of the present disclosure, in the eighth aspect, a width of the first electrode finger in the first end region may be longer than the first reference width, a width of the first electrode finger in the second end region may be shorter than the first reference width, a width of the second electrode finger in the second end region may be longer than the second reference width, a width of the second electrode finger in the first end region may be shorter than the second reference width, a duty of the first electrode finger in the non-end region is referred to as a first reference duty, a duty of the first electrode finger in the first end region is larger than the first reference duty, and The duty of the first electrode finger in the second end region may be 1.25 times or less than the first reference duty, the duty of the first electrode finger in the second end region may be 0.75 times or more than the first reference duty and smaller than the first reference duty, the duty of the second electrode finger in the non-end region is referred to as a second reference duty, the duty of the second electrode finger in the first end region may be 0.75 times or more than the second reference duty and smaller than the second reference duty, and the duty of the second electrode finger in the second end region may be greater than the second reference duty and 1.25 times or less than the second reference duty.

[0119] In an elastic wave device according to aspect 10 of the present disclosure, in aspect 8, a width of the first electrode finger in the first end region may be shorter than the first reference width, a width of the first electrode finger in the second end region may be longer than the first reference width, a width of the second electrode finger in the second end region may be shorter than the second reference width, a width of the second electrode finger in the first end region may be longer than the second reference width, a duty of the first electrode finger in the non-end region is referred to as a first reference duty, and a duty of the first electrode finger in the first end region is 0.75 times or more of the first reference duty, and may be smaller than the first reference duty, the duty of the first electrode finger in the second end region may be greater than the first reference duty and not more than 1.25 times the first reference duty, the duty of the second electrode finger in the non-end region is referred to as a second reference duty, the duty of the second electrode finger in the first end region may be greater than the second reference duty and not more than 1.25 times the second reference duty, and the duty of the second electrode finger in the second end region may be greater than the second reference duty and not more than 0.75 times the second reference duty and smaller than the second reference duty.

[0120] In an elastic wave device according to an eleventh aspect of the present disclosure, in any one of the first to seventh aspects, a length of the first electrode finger in the first direction in the non-end region is referred to as a first reference width, a thickness of the first electrode finger in the non-end region is referred to as a first reference thickness, the width of the first electrode finger in the first end region may be longer than the first reference width, the width of the first electrode finger in the second end region may be less than the first reference width, the thickness of the first electrode finger in the first end region may be greater than the first reference thickness, and the thickness of the first electrode finger in the second end region may be greater than the first reference thickness. The length of the second electrode finger in the first direction in the non-end region is referred to as a second reference width, and the thickness of the second electrode finger in the non-end region is referred to as a second reference thickness. The width of the second electrode finger in the second end region may be longer than the second reference width, the width of the second electrode finger in the first end region may be less than the second reference width, the thickness of the second electrode finger in the second end region may be greater than the second reference thickness, and the thickness of the second electrode finger in the first end region may be less than the second reference thickness.

[0121] In an acoustic wave device according to a twelfth aspect of the present disclosure, in any one of the first to seventh aspects, a length of the first electrode finger in the non-end region in the first direction is referred to as a first reference width. a thickness of the first electrode finger in the non-end region is referred to as a first reference thickness, a width of the first electrode finger in the first end region may be less than the first reference width, a width of the first electrode finger in the second end region may be greater than the first reference width, a thickness of the first electrode finger in the first end region may be smaller than the first reference thickness, and a thickness of the first electrode finger in the second end region may be greater than the first reference thickness; a length of the second electrode finger in the first direction in the non-end region is referred to as a second reference width, a thickness of the second electrode finger in the non-end region is referred to as a second reference thickness, a width of the second electrode finger in the second end region may be less than the second reference width, a width of the second electrode finger in the first end region may be greater than the second reference width, a thickness of the second electrode finger in the second end region may be smaller than the second reference thickness, and a thickness of the second electrode finger in the first end region may be greater than the second reference thickness.

[0122] A thirteenth aspect of the present disclosure relates to an acoustic wave device in accordance with any one of the first to twelfth aspects, wherein at least one of the first electrode finger and the second electrode finger has an additional film.

[0123] An elastic wave device according to aspect 14 of the present disclosure is any one of aspects 1 to 13, wherein the elastic wave device has first dummy electrode fingers and second dummy electrode fingers extending in the second direction, the first dummy electrode fingers may be connected to the first bus bar and extend toward the second bus bar, the second dummy electrode fingers may be connected to the second bus bar and extend toward the first bus bar, the first dummy electrode fingers may face the second electrode fingers in the second direction, and the second dummy electrode fingers may face the first electrode fingers in the second direction, and when taking into account the imaginary cut plane, a cross-sectional area of ​​the first dummy electrode fingers may be 0.75 to 1.25 times the cross-sectional area of ​​the first electrode fingers in the first end region, and a cross-sectional area of ​​the second dummy electrode fingers may be 0.75 to 1.25 times the cross-sectional area of ​​the second electrode fingers in the second end region.

[0124] In an acoustic wave device according to a fifteenth aspect of the present disclosure, in any one of the first to fourteenth aspects, the IDT electrode may be configured to excite a plate wave.

[0125] In the acoustic wave device according to a sixteenth aspect of the present disclosure, in any one of the first to fifteenth aspects, the IDT electrode may be configured to excite a wave in an A1 mode.

[0126] In an acoustic wave device according to a seventeenth aspect of the present disclosure, in any one of the first to sixteenth aspects, the IDT electrode may be configured to excite a bulk wave.

[0127] An elastic wave device according to an eighteenth aspect of the present disclosure is any one of the first to seventeenth aspects, and may further include a support substrate and an acoustic reflection film located between the support substrate and the piezoelectric layer.

[0128] An elastic wave device according to aspect 19 of the present disclosure may be any one of aspects 1 to 17, and may have a support substrate, and the elastic wave device may include a membrane structure having a hollow portion surrounded by the support substrate and the piezoelectric layer.

[0129] A communication device according to a twentieth aspect of the present disclosure may include the acoustic wave device according to any one of the first to nineteenth aspects.

[0130] [Additional Notes] The invention according to the present disclosure has been described above based on the drawings and examples. However, the invention according to the present disclosure is not limited to the above-mentioned 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 the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments are also included in the technical scope of the invention according to the present disclosure. In other words, it should be noted that a person skilled in the art can easily make various modifications or corrections based on the present disclosure. It should also be noted that these modifications or corrections are included in the scope of the present disclosure. [Explanation of symbols]

[0131] 1. 1V acoustic wave device 2 Piezoelectric layer 3 IDT electrode 5 Acoustic reflective film 6 Support substrate 31a 1st busbar 31b 2nd bus bar 32a 1st electrode finger 32b 2nd electrode finger 35a First dummy electrode finger 35b Second dummy electrode finger 151 Communication equipment 321a 1st regular part 321b 2nd regular part 322a First wide section 322b 2nd wide section 323a 1st narrow part 323b 2nd narrow part 326a 1st thin section 326b 2nd thin section CR intersection area TB1 1st end area TB2 2nd end area NTB non-edge area MA hollow part

Claims

1. 1. An acoustic wave device, comprising: A piezoelectric layer; an IDT electrode located on the piezoelectric layer, The IDT electrode is a first electrode finger and a second electrode finger adjacent to each other in a first direction and extending in a second direction intersecting the first direction; a first bus bar and a second bus bar opposed to each other in the second direction, the first electrode finger is connected to the first bus bar and extends to a side of the second bus bar; the second electrode finger is connected to the second bus bar and extends toward the first bus bar; In the elastic wave device, an intersection region where the first electrode fingers and the second electrode fingers intersect includes, in the second direction, (i) a first end region located on the first bus bar side, (ii) a second end region located on the second bus bar side, and (iii) a non-end region located between the first end region and the second end region, a thickness of the piezoelectric layer is equal to or smaller than twice the electrode finger pitch between the first electrode fingers and the second electrode fingers; a length of each of the first end region and the second end region in the second direction is equal to or greater than the electrode finger pitch and is equal to or less than 2.5 times the electrode finger pitch; When a virtual cut surface extending in the first direction and a thickness direction of the elastic wave device is considered, a cross-sectional area of ​​the first electrode finger in the non-end region is referred to as a first reference cross-sectional area, a cross-sectional area of ​​the second electrode finger in the non-end region is referred to as a second reference cross-sectional area, when a cross-sectional area of ​​the first electrode finger in the first end region is larger than the first reference cross-sectional area and a cross-sectional area of ​​the second electrode finger in the second end region is larger than the second reference cross-sectional area, a cross-sectional area of ​​the first electrode finger in the second end region is smaller than the first reference cross-sectional area and a cross-sectional area of ​​the second electrode finger in the first end region is smaller than the second reference cross-sectional area, An elastic wave device, wherein when the cross-sectional area of ​​the first electrode finger in the first end region is smaller than the first reference cross-sectional area and the cross-sectional area of ​​the second electrode finger in the second end region is smaller than the second reference cross-sectional area, the cross-sectional area of ​​the first electrode finger in the second end region is larger than the first reference cross-sectional area and the cross-sectional area of ​​the second electrode finger in the first end region is larger than the second reference cross-sectional area.

2. 2. The elastic wave device according to claim 1, wherein an absolute value of a difference between a cross-sectional area of ​​the first electrode finger in the first end region and the first reference cross-sectional area is 0.75 times or more and 1.25 times or less of an absolute value of a difference between a cross-sectional area of ​​the second electrode finger in the first end region and the second reference cross-sectional area.

3. 2. The elastic wave device according to claim 1, wherein an absolute value of a difference between a cross-sectional area of ​​the first electrode finger in the second end region and the first reference cross-sectional area is 0.75 times or more and 1.25 times or less of an absolute value of a difference between a cross-sectional area of ​​the second electrode finger in the second end region and the second reference cross-sectional area.

4. 2. The elastic wave device according to claim 1, wherein an absolute value of a difference between a cross-sectional area of ​​the first electrode finger in the first end region and the first reference cross-sectional area is 0.75 times or more and 1.25 times or less of an absolute value of a difference between a cross-sectional area of ​​the second electrode finger in the second end region and the second reference cross-sectional area.

5. 2. The elastic wave device according to claim 1, wherein an absolute value of a difference between a cross-sectional area of ​​the first electrode finger in the second end region and the first reference cross-sectional area is 0.75 times or more and 1.25 times or less of an absolute value of a difference between a cross-sectional area of ​​the second electrode finger in the first end region and the second reference cross-sectional area.

6. a cross-sectional area of ​​the first electrode finger in the first end region is larger than the first reference cross-sectional area; a cross-sectional area of ​​the first electrode finger in the second end region is smaller than the first reference cross-sectional area; a cross-sectional area of ​​the second electrode finger in the second end region is larger than the second reference cross-sectional area; The acoustic wave device according to claim 1 , wherein a cross-sectional area of ​​the second electrode finger in the first end region is smaller than the second reference cross-sectional area.

7. a cross-sectional area of ​​the first electrode finger in the first end region is smaller than the first reference cross-sectional area; a cross-sectional area of ​​the first electrode finger in the second end region is larger than the first reference cross-sectional area; a cross-sectional area of ​​the second electrode finger in the second end region is smaller than the second reference cross-sectional area; The acoustic wave device according to claim 1 , wherein a cross-sectional area of ​​the second electrode finger in the first end region is larger than the second reference cross-sectional area.

8. a length of the first electrode finger in the non-end region in the first direction is referred to as a first reference width, a length of the second electrode finger in the non-end region in the first direction is referred to as a second reference width, when the width of the first electrode finger in the first end region is longer than the first reference width and the width of the second electrode finger in the second end region is longer than the second reference width, the width of the first electrode finger in the second end region is shorter than the first reference width and the width of the second electrode finger in the first end region is shorter than the second reference width, The elastic wave device of claim 1, wherein when the width of the first electrode finger in the first end region is shorter than the first reference width and the width of the second electrode finger in the second end region is shorter than the second reference width, the width of the first electrode finger in the second end region is longer than the first reference width and the width of the second electrode finger in the first end region is longer than the second reference width.

9. a width of the first electrode finger in the first end region is greater than the first reference width; a width of the first electrode finger in the second end region is shorter than the first reference width; a width of the second electrode finger in the second end region is greater than the second reference width; a width of the second electrode finger in the first end region is shorter than the second reference width; The duty of the first electrode finger in the non-end region is referred to as a first reference duty, a duty of the first electrode finger in the first end region is greater than the first reference duty and is equal to or less than 1.25 times the first reference duty; a duty of the first electrode finger in the second end region is equal to or greater than 0.75 times the first reference duty and is smaller than the first reference duty; The duty of the second electrode finger in the non-end region is referred to as a second reference duty, a duty of the second electrode finger in the first end region is equal to or greater than 0.75 times the second reference duty and is smaller than the second reference duty; The acoustic wave device according to claim 8 , wherein a duty of the second electrode finger in the second end region is greater than the second reference duty and is equal to or less than 1.25 times the second reference duty.

10. a width of the first electrode finger in the first end region is shorter than the first reference width; a width of the first electrode finger in the second end region is greater than the first reference width; a width of the second electrode finger in the second end region is shorter than the second reference width; a width of the second electrode finger in the first end region is greater than the second reference width; The duty of the first electrode finger in the non-end region is referred to as a first reference duty, a duty of the first electrode finger in the first end region is equal to or greater than 0.75 times the first reference duty and is smaller than the first reference duty; a duty of the first electrode finger in the second end region is greater than the first reference duty and is equal to or less than 1.25 times the first reference duty; The duty of the second electrode finger in the non-end region is referred to as a second reference duty, a duty of the second electrode finger in the first end region is greater than the second reference duty and is equal to or less than 1.25 times the second reference duty; The acoustic wave device according to claim 8 , wherein a duty of the second electrode finger in the second end region is equal to or greater than 0.75 times the second reference duty and is smaller than the second reference duty.

11. a length of the first electrode finger in the non-end region in the first direction is referred to as a first reference width, a thickness of the first electrode finger in the non-end region is referred to as a first reference thickness; a width of the first electrode finger in the first end region is greater than the first reference width; a width of the first electrode finger in the second end region is equal to or smaller than the first reference width, a thickness of the first electrode finger in the first end region is equal to or greater than a first reference thickness; a thickness of the first electrode finger in the second end region is smaller than a first reference thickness; a length of the second electrode finger in the non-end region in the first direction is referred to as a second reference width, a thickness of the second electrode finger in the non-end region is referred to as a second reference thickness; a width of the second electrode finger in the second end region is greater than the second reference width; a width of the second electrode finger in the first end region is equal to or smaller than the second reference width, a thickness of the second electrode finger in the second end region is equal to or greater than a second reference thickness; The acoustic wave device according to claim 1 , wherein a thickness of the second electrode finger in the first end region is smaller than a second reference thickness.

12. a length of the first electrode finger in the non-end region in the first direction is referred to as a first reference width, a thickness of the first electrode finger in the non-end region is referred to as a first reference thickness; a width of the first electrode finger in the first end region is equal to or smaller than the first reference width, a width of the first electrode finger in the second end region is greater than the first reference width; a thickness of the first electrode finger in the first end region is smaller than a first reference thickness; a thickness of the first electrode finger in the second end region is equal to or greater than a first reference thickness; a length of the second electrode finger in the non-end region in the first direction is referred to as a second reference width, a thickness of the second electrode finger in the non-end region is referred to as a second reference thickness; a width of the second electrode finger in the second end region is equal to or smaller than the second reference width, a width of the second electrode finger in the first end region is greater than the second reference width; a thickness of the second electrode finger in the second end region is smaller than a second reference thickness; The acoustic wave device according to claim 1 , wherein a thickness of the second electrode finger in the first end region is equal to or greater than a second reference thickness.

13. The acoustic wave device according to claim 1 , wherein at least one of the first electrode fingers and the second electrode fingers has an additional film.

14. the acoustic wave device has first dummy electrode fingers and second dummy electrode fingers extending in the second direction, the first dummy electrode finger is connected to the first bus bar and extends to a side of the second bus bar, the second dummy electrode finger is connected to the second bus bar and extends toward the first bus bar, the first dummy electrode finger faces the second electrode finger in the second direction, the second dummy electrode finger faces the first electrode finger in the second direction, When the virtual cutting plane is taken into consideration, a cross-sectional area of ​​the first dummy electrode finger is 0.75 to 1.25 times a cross-sectional area of ​​the first electrode finger in the first end region, The acoustic wave device according to claim 1 , wherein a cross-sectional area of ​​the second dummy electrode finger is 0.75 to 1.25 times a cross-sectional area of ​​the second electrode finger in the second end region.

15. The acoustic wave device according to claim 1 , wherein the IDT electrode is configured to excite a plate wave.

16. The acoustic wave device according to claim 1 , wherein the IDT electrode is configured to excite a wave in an A1 mode.

17. The acoustic wave device of claim 1 , wherein the IDT electrode is configured to excite a bulk wave.

18. The acoustic wave device includes: A support substrate; The acoustic wave device according to claim 1 , further comprising an acoustic reflection film located between the support substrate and the piezoelectric layer.

19. The acoustic wave device includes a support substrate, The acoustic wave device according to claim 1 , comprising a membrane structure having a hollow portion surrounded by the support substrate and the piezoelectric layer.

20. A communication device comprising the acoustic wave device according to claim 1.

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