Elastic wave device, filter, splitter and communication device

Abstract

According to the present invention, an IDT electrode comprises: a first busbar; a second busbar opposing the first busbar; a plurality of first electrode fingers each electrically connected to the first busbar; a plurality of second electrode fingers each electrically connected to the second busbar and arranged alternately with the first electrode fingers in an elastic wave propagation direction; a plurality of bar electrodes that are interposed between the first busbar and the first electrode fingers, that extend parallel to the first busbar, and that extend parallel to each other; and a plurality of connection parts including a connection part interposed between, and connecting, the first busbar and a corresponding one of the bar electrodes adjacent to the first busbar, and a connection part interposed between, and connecting, the adjacent bar electrodes. At least a portion of the connection parts is arranged discontinuously in the extending direction of the electrode fingers.

Description

[Technical field]

[0001] The present disclosure relates to an acoustic wave device capable of at least one of converting an acoustic wave to an electrical signal and converting an electrical signal to an acoustic wave, a filter including the acoustic wave device, a splitter including the filter, and a communication device including the splitter. [Background technology]

[0002] A known acoustic wave device has a piezoelectric layer and an IDT (Interdigital Transducer) electrode located on the piezoelectric layer (for example, see Patent Document 1 below). The IDT electrode has a pair of comb-tooth electrodes. Each comb-tooth electrode has a bus bar and a plurality of electrode fingers extending in parallel from the bus bar. The pair of comb-tooth electrodes are arranged to interdigitate with each other. Patent Document 1 discloses an IDT electrode in which a bus bar has a plurality of openings arranged in the direction in which the bus bar extends. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-77956 Summary of the Invention

[0004] An acoustic wave device according to an aspect of the present disclosure includes a piezoelectric body having a first surface and an IDT electrode located on the first surface. The IDT electrode includes a first bus bar, a second bus bar, a plurality of first electrode fingers, a plurality of second electrode fingers, a plurality of bar electrodes, and a plurality of connection portions. The second bus bar faces the first bus bar. The plurality of first electrode fingers are electrically connected to the first bus bar. The plurality of second electrode fingers are electrically connected to the second bus bar, and are arranged alternately with the plurality of first electrode fingers in an acoustic wave propagation direction. The plurality of bar electrodes are interposed between the first bus bar and between the plurality of first electrode fingers, and extend in parallel to the first bus bar and in parallel to each other. The plurality of connection portions include a connection portion interposed between the first bus bar and a bar electrode adjacent to the first bus bar to connect them, and a connection portion interposed between adjacent bar electrodes to connect them. At least some of the plurality of connection portions are arranged discontinuously with respect to the extending direction of the plurality of first electrode fingers.

[0005] A filter according to one embodiment of the present disclosure includes the above-described acoustic wave device and one or more other IDT electrodes located on the first surface and connected in a ladder configuration with the IDT electrode to form a ladder filter.

[0006] A filter according to one embodiment of the present disclosure includes the above-described acoustic wave device and one or more other IDT electrodes located on the first surface and aligned in the acoustic wave propagation direction with respect to the IDT electrode to form a multi-mode filter.

[0007] A duplexer according to an aspect of the present disclosure includes an antenna terminal, a transmission filter connected to the antenna terminal, and a reception filter connected to the antenna terminal, wherein at least one of the transmission filter and the reception filter is configured by any one of the filters described above.

[0008] A communication device according to one embodiment of the present disclosure includes the above-mentioned splitter, an antenna connected to the antenna terminal, and an IC (Integrated Circuit) connected to the transmit filter and the receive filter. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a plan view illustrating a configuration of an elastic wave device according to a preferred embodiment of the present invention. [Diagram 2] 2 is an enlarged view of region II in FIG. 1, showing a part of a specific example of an IDT electrode. [Figure 3A] 11 is a diagram showing another specific example (second example) of the IDT electrode. FIG. [Figure 3B] FIG. 13 is a diagram showing still another specific example (third example) of the IDT electrode. [Figure 3C] FIG. 13 is a diagram showing still another specific example (fourth example) of the IDT electrode. [Figure 3D] FIG. 13 is a diagram showing still another specific example (fifth example) of the IDT electrode. [Figure 4A] FIG. 13 is a diagram showing still another specific example (sixth example) of the IDT electrode. [Figure 4B] FIG. 13 is a diagram showing still another specific example (seventh example) of the IDT electrode. [Figure 4C] FIG. 13 is a diagram showing still another specific example (eighth example) of the IDT electrode. [Figure 4D] FIG. 13 is a diagram showing still another specific example (ninth example) of the IDT electrode. [Figure 4E] FIG. 13 is a diagram showing still another specific example (tenth example) of the IDT electrode. [Diagram 5] FIG. 11 is a diagram showing still another specific example (eleventh example) of the IDT electrode. [Figure 6] 6 is a diagram showing an example of a cross section taken along line VI-VI in FIG. [Figure 7] 6 is a diagram showing another example of a cross section taken along line VI-VI in FIG. [Figure 8] 1 is a plan view illustrating a configuration of an elastic wave resonator according to a preferred embodiment of the present invention. [Figure 9]1 is a circuit diagram illustrating a configuration of a duplexer according to an embodiment of the present invention. [Figure 10] 1 is a block diagram showing a configuration of a communication device according to an embodiment. [Figure 11] FIG. 4 is a diagram showing characteristics of the resonators according to the first comparative example and the first embodiment. [Figure 12] FIG. 4 is a diagram showing the characteristics of the resonators according to the first to third embodiments. [Figure 13] 13 is a diagram showing the characteristics of the resonators according to the second and third comparative examples and the fourth embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, embodiments according to the present disclosure will be described with reference to the drawings. The drawings used in the following description are schematic. Therefore, for example, the dimensional ratios in the drawings do not necessarily match the actual ones. The dimensional ratios may not match between drawings. Certain shapes or dimensions may be shown exaggerated.

[0011] In the elastic wave device according to the present disclosure, any direction may be upward or downward. However, in the following, for convenience, an orthogonal coordinate system consisting of the D1 axis, the D2 axis, and the D3 axis is defined, and terms such as upper surface and lower surface may be used with the positive side of the D3 axis being upward. In addition, when referring to a plan view or a plan perspective view, unless otherwise specified, it refers to a view in the D3 direction. Note that the D1 axis is defined to be parallel to the propagation direction of an elastic wave propagating along the upper surface of a piezoelectric body described later, the D2 axis is defined to be parallel to the upper surface of the piezoelectric body and perpendicular to the D1 axis, and the D3 axis is defined to be perpendicular to the upper surface of the piezoelectric body.

[0012] <Elastic wave device> (Overview of Elastic Wave Device) FIG. 1 is a plan view showing a configuration of a main part of an elastic wave device 1 (hereinafter, sometimes simply referred to as "device 1") according to a preferred embodiment of the present invention.

[0013] The device 1 has, for example, a piezoelectric body 3 (see FIG. 6 described later, etc.) and an IDT electrode 5 located on an upper surface 3a (an example of a first surface) of the piezoelectric body 3. FIG. 1 shows a plan view of the upper surface 3a. However, the reference numerals relating to the piezoelectric body 3 and the outer edge of the upper surface 3a are omitted from the illustration.

[0014] By applying a voltage to the IDT electrode 5, an elastic wave is excited that propagates in the D1 direction in the intersection region R0 of the piezoelectric body 3 (the region on the central side of the IDT electrode 5 in the D2 direction). And / or, by the elastic wave propagating in the D1 direction through the intersection region R0, an electric charge is generated in the piezoelectric body 3, and a voltage is applied to the IDT electrode 5. The device 1 may, for example, configure a resonator and / or a filter that utilizes such conversion between an elastic wave and a voltage (electrical signal). Note that, hereinafter, the D1 direction may be referred to as the elastic wave propagation direction or the propagation direction, etc.

[0015] The IDT electrode 5 is formed of a conductor layer overlapping the upper surface 3a of the piezoelectric body 3. The IDT electrode 5 also includes a pair of comb-tooth electrodes 7. Each comb-tooth electrode 7 includes, for example, a bus bar 9 and a plurality of electrode fingers 11 electrically connected to the bus bar 9. The pair of comb-tooth electrodes 7 are arranged such that the plurality of electrode fingers 11 interdigitate with (intersect with) each other. The above-mentioned intersection region R0 is a region where the plurality of electrode fingers 11 of one comb-tooth electrode 7 and the plurality of electrode fingers 11 of the other comb-tooth electrode 7 overlap in the acoustic wave propagation direction.

[0016] Generally, in each comb-tooth electrode 7, the multiple electrode fingers 11 extend from the bus bar 9. That is, the two are directly connected. On the other hand, in this embodiment, each comb-tooth electrode 7 has an interposed electrode 41 interposed between the bus bar 9 and the multiple electrode fingers 11. This makes it possible to reduce, for example, spurious responses in the transverse mode, as will be described in detail later.

[0017] In the device 1, the configuration other than the configuration related to the intervening electrode 41 may be variously configured, for example, may be configured in a known manner. Description of the configuration that may be configured in such a known manner will be omitted as appropriate.

[0018] The embodiments will be described in the following order. IDT electrode 5 (mainly the part other than the intermediate electrode 41) (FIG. 1) ·Interposed electrode 41 (Figure 2) Various specific examples of the IDT electrode 5 (particularly the intervening electrode 41) (FIGS. 2 to 5) Elastic wave velocity profile (Figure 1) Various configuration examples of substrates containing piezoelectric materials (Figures 6 and 7) Other configurations of acoustic wave devices Summary of acoustic wave devices

[0019] (IDT electrode) The busbars 9 are formed, for example, in an elongated shape that extends linearly in the propagation direction (direction D1) of the elastic waves with a substantially constant width. The pair of busbars 9 face each other in a direction (direction D2) perpendicular to the propagation direction of the elastic waves. The edges of each busbar 9 on the intersection region R0 side are, for example, linear. Furthermore, the edges of the pair of busbars 9 on the intersection region R0 side are, for example, parallel to each other (the concept of "parallel" may be extended to "curve"). From another perspective, the distance between both edges (direction D2) is constant regardless of the position in the direction D1.

[0020] Unlike the illustrated example, the busbars 9 may have a variable width or may be inclined with respect to the propagation direction of the elastic waves. Furthermore, the edge of each busbar 9 on the side of the intersection region R0 may be curved or may be formed of a plurality of straight lines intersecting each other. Furthermore, the distance between the opposing edges of a pair of busbars 9 may vary depending on the position in the D1 direction.

[0021] The length of the busbar 9 (in the D1 direction) may be, for example, approximately equal to the product of the pitch p and the number of electrode fingers 11 in a pair of comb-tooth electrodes 7. The width of the busbar 9 (in the D2 direction) is arbitrary. In general, the width of the busbar 9 is greater than the width of the electrode fingers 11 (in the D1 direction). For example, the width of the busbar 9 may be 1p or more.

[0022] The electrode fingers 11 have, for example, the same shape and size. Unlike the illustrated example, the electrode fingers 11 may have different shapes and / or sizes. For example, the electrode fingers 11 may have different lengths. That is, the IDT electrode 5 may be so-called apodized.

[0023] Each electrode finger 11 is formed, for example, in an elongated shape with its center line extending linearly in a direction (direction D2) perpendicular to the propagation direction of the elastic wave. The electrode finger 11 may extend with a constant width (length in the direction D1), or the width may vary depending on the position in the length direction (direction D2) (illustrated example). In the example shown in FIG. 1, the electrode finger 11 has widened portions 11b at the tip and base sides that are wider than the remaining majority (main portion 11a). This utilizes a so-called piston mode (or a mode similar thereto; the same applies below), and thus reduces spurious in the transverse mode. Note that in the description of this embodiment, some expressions are used assuming this mode.

[0024] In each comb-tooth electrode 7, the multiple electrode fingers 11 are arranged in the propagation direction of the elastic wave. In each comb-tooth electrode 7, a line (not shown) connecting the tips (or bases) of the multiple electrode fingers 11 is, for example, a straight line parallel to the propagation direction. However, unlike the example shown in the figure, the line may be inclined to the propagation direction, may be curved, or may be a shape consisting of multiple straight lines intersecting each other. In an embodiment in which the piston mode is used as described above, the line may be, for example, a straight line parallel to or inclined with respect to the propagation direction.

[0025] A plurality of electrode fingers 11 of one comb electrode 7 and the electrode fingers 11 of the other comb electrode 7 are alternately arranged in the propagation direction of the elastic wave. When referring to this, the plurality of electrode fingers 11 of one comb electrode 7 and the electrode fingers 11 of the other comb electrode 7 may be alternately arranged one by one (the illustrated example), or may be alternately arranged in numbers of two or more. Also, there may be specific parts due to so-called thinning or the like. In the description of the embodiment, the mode of being alternately arranged one by one will be taken as an example.

[0026] The pitch p of the plurality of electrode fingers 11 in a pair of comb electrodes 7 (for example, the center - to - center distance between two adjacent electrode fingers 11) is basically constant within the IDT electrode 5. Note that the IDT electrode 5 may have a specific part regarding the pitch p. Examples of the specific part include a narrow - pitch part where the pitch p is narrower than most parts (for example, 80% or more), a wide - pitch part where the pitch p is wider than most parts, and a thinning part where a small number of electrode fingers 11 are substantially thinned.

[0027] In the description of the embodiment, when referring to the pitch p, unless otherwise specified, it refers to the pitch of the part (the majority of the plurality of electrode fingers 11) excluding the above - mentioned specific parts. Also, in the case where the pitch changes even in the majority of the plurality of electrode fingers 11 excluding the specific parts, the average value of the pitch of the majority of the plurality of electrode fingers 11 may be used as the value of the pitch p.

[0028] The number of electrode fingers 11 may be appropriately set according to the electrical characteristics required for the IDT electrode 5 (device 1). Since FIG. 1 is a schematic diagram, the number of electrode fingers 11 is shown as small. In reality, more electrode fingers 11 than shown in the figure may be arranged. For example, the number of electrode fingers 11 may be 100 or more. Note that FIG. 1 may be regarded as a figure showing an extraction of a part of the IDT electrode 5.

[0029] The tip of each electrode finger 11 of one comb-tooth electrode 7 faces an edge of an interposed electrode 41 (more specifically, a bar electrode 43 (described later) closest to the electrode finger 11) of the other comb-tooth electrode 7 via a gap G1. The lengths of the multiple gaps G1 in the D2 direction are, for example, the same as each other. The length may be set appropriately and may be, for example, not less than 0.1p and not more than 0.5p.

[0030] When a voltage is applied to a pair of comb-tooth electrodes 7, the voltage is applied to the upper surface 3a of the piezoelectric body 3 by the electrode fingers 11, and the upper surface of the piezoelectric body 3 (when the piezoelectric body 3 is relatively thick) or the entire piezoelectric body 3 (when the piezoelectric body 3 is relatively thin) vibrates. This excites an elastic wave propagating along the upper surface 3a. At this time, the multiple elastic waves excited by the electrode fingers 11 are in phase with each other in a direction perpendicular to the multiple electrode fingers 11 (direction D1) when their half wavelengths are approximately equal to the pitch p, and their amplitudes are added together. That is, the elastic wave propagating in the direction D1 with the pitch p as the half wavelength is most likely to be excited. As a result, of the voltage applied to the IDT electrode 5, a component having a frequency approximately equal to the frequency of an elastic wave having a half wavelength of the pitch p is mainly converted into an elastic wave. Moreover, when an elastic wave is generated in the region of the upper surface 3a where the pair of comb-tooth electrodes 7 are arranged, the elastic wave propagating in the direction D1 is converted into a voltage with the pitch p being roughly a half wavelength, by the opposite principle to the above. Using such a principle, a resonator or a filter is realized.

[0031] In the device 1, an elastic wave of an appropriate mode may be used. For example, the elastic wave may be a surface acoustic wave (SAW). For example, a Rayleigh wave or a leaky wave may be used as the SAW. Furthermore, the elastic wave may be a plate wave propagating through a thin plate-like piezoelectric body. For example, an A1 mode Lamb wave, an S0 mode Lamb wave, and an SH (Shear Horizontal) type plate wave may be used as the plate wave. Furthermore, the mode of the elastic wave does not have to be clearly specified or distinguished in this way.

[0032] As described above, the pitch p of the electrode fingers 11 is basically half the wavelength of an elastic wave having a frequency equivalent to the intended resonant frequency. An example of the absolute value of the pitch p is 0.5 μm or more and 15 μm or less. The length (D2 direction) of the electrode fingers 11 may be, for example, 10p or more or 20p or more, and may be 100p or less or 50p or less. The above lower and upper limits may be combined in any manner.

[0033] The ratio (=width / 2p) of the width (D1 direction) of electrode finger 11 to twice the pitch p (2p) of electrode finger 11 may be referred to as the duty ratio. The duty ratio may be set appropriately. For example, the duty ratio of main portion 11a (or electrode finger 11 having a constant width over the entire length) may be set to 0.40 or more or 0.45 or more, and may be set to 0.60 or less or 0.55 or less. The upper and lower limits may be combined in any manner. The duty ratio of widened portion 11b may be set to 0.50 or more or 0.55 or more, and may be set to 0.80 or less, 0.70 or less, or 0.65 or less, provided that the duty ratio is greater than the duty ratio of main portion 11a. The upper and lower limits may be combined in any manner.

[0034] In the illustrated example, in an embodiment in which each electrode finger 11 has one main portion 11a and two widened portions 11b, their lengths (in the D2 direction) may be set appropriately. For example, the length of one widened portion 11b may be 0.5p or more, 0.7p or more, or 0.9p or more, and may be 2p or less, 1.5p or less, or 1.1p or less. The above upper and lower limits may be combined in any manner.

[0035] The thickness of the IDT electrode 5 (conductor layer) is, for example, generally constant regardless of the position in the planar direction (the direction parallel to the D1-D2 plane). The thickness of the conductor layer may be set appropriately depending on the characteristics required for the device 1. For example, the thickness of the conductor layer may be 0.04p or more and 0.20p or less, and / or 50 nm or more and 600 nm or less.

[0036] The conductor layer is formed of, for example, a metal. The metal may be of any suitable type, for example, aluminum (Al) or an alloy (Al alloy) mainly composed of Al. The Al alloy is, for example, an Al-copper (Cu) alloy. The conductor layer may be composed of a plurality of metal layers. For example, the conductor layer may be composed of a relatively thin layer of titanium (Ti) overlapping the upper surface 3a of the piezoelectric body 3, and Al or an Al alloy overlapping thereon. Ti contributes to, for example, strengthening the bonding between the Al or Al alloy and the piezoelectric body 3.

[0037] (intervening electrode) FIG. 2 is an enlarged view of region II in FIG.

[0038] As will be illustrated later, the intervening electrode 41 may have various specific shapes. Fig. 2 illustrates an intervening electrode 41A according to a first example. In the description given with reference to Fig. 2 (and drawings similar to Fig. 2), unless otherwise specified or unless a contradiction occurs, the bus bar 9, the electrode fingers 11, and the intervening electrode 41 refer to those that are connected to each other (those within one comb-tooth electrode 7).

[0039] The intermediate electrode 41 is configured, for example, generally in a lattice or mesh shape. Specifically, for example, the intermediate electrode 41 has two types of parts: a plurality of (eight in the illustrated example) bar electrodes 43 and a plurality of connection portions 45. The plurality of bar electrodes 43 extend in parallel to the bus bar 9 and also extend in parallel to each other. A region between two adjacent bar electrodes 43 (or adjacent bar electrodes 43 and bus bar 9) may be referred to as a slit region S1. Each connection portion 45 is located in the slit region S1 and connects two adjacent bar electrodes 43 (or adjacent bar electrodes 43 and bus bar 9).

[0040] At least a part (all in the illustrated example) of the multiple connection parts 45 are arranged discontinuously in the extension direction (direction D2) of the electrode fingers 11. That is, at least a part of the multiple connection parts 45 are not arranged to form a straight line parallel to direction D2 extending from the bus bar 9 to the bar electrode 43 closest to the electrode finger 11. From another perspective, at least a part of at least one connection part 45 overlaps in direction D2 with a non-arrangement area of ​​a conductor (IDT electrode 5) in at least one slit region S1 other than the slit region S1 in which it is located (for example, an adjacent slit region S1).

[0041] By arranging the multiple connection parts 45 as described above, for example, spurious can be reduced. The applicant has confirmed this effect through actual measurements of a prototype and simulation calculations, and will provide some examples later. The principles by which spurious can be reduced are as follows.

[0042] The acoustic wave is reflected at the boundary between the area where the conductor (IDT electrode 5) is arranged and the area where the conductor (IDT electrode 5) is not arranged. If all the connection parts 45 are arranged to form a straight line parallel to the D2 direction, the spurious of the transverse mode is reflected by the bar electrode 43 closest to the electrode finger 11 at the position of the straight line in the D1 direction, and is reflected by each of the bar electrodes 43 (and bus bar 9) at other positions in the D1 direction. In other words, the position in the D2 direction where reflection occurs is basically constant regardless of the position in the D1 direction. As a result, the wavelengths and the positions of the nodes and antinodes of the spurious of the transverse mode are likely to be aligned, and therefore they are likely to reinforce each other.

[0043] On the other hand, when multiple connection parts 45 are arranged discontinuously in the D2 direction as in this embodiment, there is a non-conductor area at a position overlapping with the connection parts 45 in the D2 direction. The spurious of the transverse mode is also reflected between this non-conductor area and the bar electrode 43. Furthermore, depending on the shape of the connection parts 45, reflection also occurs at the connection parts 45. The positions of these new reflections are dispersed in the D1 direction and the D2 direction. As a result, the wavelengths and the positions of the nodes and antinodes of the transverse mode spurious are dispersed, and the mutually reinforcing action is reduced.

[0044] As can be understood from the above principle, as long as the multiple connection parts 45 are arranged discontinuously in the D2 direction, the number, shape, positions, dimensions, etc. of the multiple bar electrodes 43 and the multiple connection parts 45 are arbitrary. For example, as follows.

[0045] The number of the bar electrodes 43 may be any number equal to or greater than 2. When two bar electrodes 43 are provided, two slit regions S1 are formed by the two bar electrodes 43 and the bus bar 9. Furthermore, at least two connection portions 45 located in different slit regions S1 can be arranged discontinuously in the direction D2.

[0046] The bar electrodes 43 have, for example, the same shape and dimensions as one another. Each bar electrode 43 has a shape that extends linearly with a substantially constant width. From another point of view, the shape of the edge or center line of the bar electrode 43 is the same as the shape of the edge of the bus bar 9 on the electrode finger 11 side, and / or the same as the shape of the line connecting the tip of the electrode finger 11 that faces the intervening electrode 41 across the gap G1 (the tip of the electrode finger 11 of the comb-tooth electrode 7 that meshes with the comb-tooth electrode 7 to which the bar electrode 43 of interest belongs).

[0047] To be clear, unlike the illustrated example, at least one bar electrode 43 may have a different shape and / or size from at least one other bar electrode 43. The width (D2 direction) of the bar electrode 43 may vary depending on the position in the D1 direction. The center line and / or edge of the bar electrode 43 may be curved or have a shape having a plurality of straight lines intersecting each other. In addition, the shape of the center line and / or edge of the bar electrode 43 may be different from the shape of the edge of the bus bar 9 on the electrode finger 11 side and / or may be different from the shape of the line connecting the tips of the electrode fingers 11 facing the intermediate electrode 41 across the gap G1.

[0048] The length (D1 direction) of the bar electrode 43 may be approximately equal to the length of the bus bar 9. The width of the bar electrode 43 may be smaller (in the illustrated example), equal to, or larger than the width (D2 direction) of the bus bar 9 and / or the width (D1 direction) of the electrode fingers 11. For example, the width of the bar electrode 43 may be 0.1p or more or 0.2p or more and may be 0.5p or less or 0.3p or less. The above lower and upper limits may be combined in any manner.

[0049] As described above, the multiple bar electrodes 43 extend in parallel to the bus bar 9 and also in parallel to each other. More specifically, in the illustrated example, the multiple bar electrodes 43 (e.g., center lines; the same applies below) and the edge of the bus bar 9 on the electrode finger 11 side extend parallel to each other. From another perspective, the distance between them in the D2 direction (extension direction of the electrode fingers 11) is constant regardless of the position in the D1 direction (propagation direction of the elastic wave). The extension direction of the multiple bar electrodes 43 (and the bus bar 9) is, for example, the D1 direction.

[0050] Unlike the illustrated example, a part or all of at least one bar electrode 43 may be inclined with respect to the bus bar 9, at least one other bar electrode 43, and / or the D1 direction. As a result, the bar electrode 43 may have a portion that intersects with the bus bar 9 and / or the other bar electrodes 43. In this case, however, the part of the intersecting portion may be regarded as a type of connection portion 45, and the multiple bar electrodes 43 may be regarded as not intersecting with each other.

[0051] The pitches of the multiple bar electrodes 43 (e.g., the center distance between two adjacent bar electrodes 43) are, for example, the same as each other. However, at least one pitch may be different from the other pitches. Furthermore, the pitch of the bar electrodes 43 may be smaller than (in the illustrated example), equal to, or larger than the pitch p of the electrode fingers 11. The pitch of the bar electrodes 43 may be, for example, 0.2p or more or 0.4p or more, and may be 1p or less or 0.6p or less. The above lower and upper limits may be combined in any manner.

[0052] The widths (in the D2 direction) of the multiple slit regions S1 are, for example, the same as each other. However, at least one width may be different from the others. Furthermore, the width of the slit region S1 may be smaller (in the illustrated example), equal to, or larger than the pitch p of the electrode fingers 11. For example, the width of the slit region S1 may be 0.1p or more or 0.2p or more, and may be 0.5p or less or 0.3p or less. The above lower and upper limits may be combined in any manner.

[0053] The ratio of the width of the bar electrodes 43 to the pitch of the bar electrodes 43 (the latter divided by the former; duty ratio) may be smaller, equal to, or larger than the duty ratio of the electrode fingers 11. For example, the duty ratio of the bar electrodes 43 may be 0.1 or more or 0.4 or more, and may be 0.8 or less or 0.6 or less. The above lower and upper limits may be combined in any manner.

[0054] The shapes and dimensions of the multiple connecting parts 45 are, for example, the same as each other. The discontinuity of the multiple connecting parts 45 in the D2 direction is realized by the positions of the multiple connecting parts 45 (for example, the positions of the geometric centers. The same applies below unless otherwise specified) not being located on a straight line parallel to the D2 direction (being shifted from each other in the D1 direction). However, unlike the example shown in the figure, the shapes and dimensions of the multiple connecting parts 45 may be different from each other. In this case, in addition to or instead of the shift in position in the D1 direction, discontinuity in the D2 direction may be realized by differences in the shapes and / or dimensions of the multiple connecting parts 45.

[0055] The shape of the connection part 45 may be, for example, a rectangular shape having four sides parallel to the D1 direction and the D2 direction (see FIG. 4A), a parallelogram shape having two sides parallel to the D1 direction (example of FIG. 2), or a shape that cannot be classified as either of these (see, for example, FIG. 5). The length of the connection part 45 in the D2 direction is equal to the width of the slit region S1, and the width is as described above. The length of the connection part 45 in the D1 direction may be set appropriately. For example, the length of the connection part 45 in the D1 direction may be shorter, equal to, or longer than the length of the connection part 45 in the D2 direction. Also, for example, the length of the connection part 45 in the D1 direction may be 0.1p or more, 0.3p or more, or 0.5p or more, and may be 1p or less, 0.8p or less, or 0.7p or less. The above lower limit and upper limit may be combined in any manner.

[0056] (Various concrete examples of IDT electrodes (especially interposed electrodes)) 3A to 5 are plan views showing other specific examples of the IDT electrode 5 (particularly the intervening electrode 41). Like FIG. 2, FIGS. 3A to 3D and 5 show a range corresponding to region II in FIG. 1. FIGS. 4A to 4E show a partial range of a pair of comb-tooth electrodes 7 in the D1 direction. Note that although the orthogonal coordinate system D1-D2-D3 is omitted in FIGS. 3A to 4E, like FIG. 2, the left-right direction in the figures is the D1 direction, and the up-down direction in the figures is the D2 direction.

[0057] In the various specific examples illustrated in these figures, mainly, the arrangements of the plurality of connection portions 45 are different from each other. Hereinafter, each specific example will be described in order starting from FIG. 2. Note that, after the description of the IDT electrode 5A (intermediate electrode 41A) shown in FIG. 2, basically, the differences from the IDT electrode 5 described above will be described. For matters not particularly mentioned, they may be the same as the IDT electrode 5 described above or inferred from the IDT electrode 5 described above. Also, even if corresponding portions among a plurality of specific examples have different shapes from each other, for convenience, the same reference numerals may be used for such portions.

[0058] (First Example of IDT Electrode) In the IDT electrode 5A (intermediate electrode 41A) shown in FIG. 2, the plurality of connection portions 45 are arranged so as to form a straight line inclined in the D2 direction. The straight line extends, for example, from the bus bar 9 to the bar electrode 43 closest to the electrode finger 11 side. Also, focusing on two adjacent straight lines in the D1 direction, the plurality of connection portions 45 are arranged in a V shape that closes (or opens) toward the electrode finger 11 side. In the illustrated example, a plurality of Vs are arranged so as to be connected to each other in the D1 direction. In other words, the plurality of connection portions 45 are arranged on a line extending in a zigzag manner in the D1 direction. Note that, different from the illustrated example, one V may be located at a specific position in the D1 direction, or adjacent Vs may be separated from each other.

[0059] In the example of FIG. 2, in the slit region S1 closest to the electrode finger 11 side, two connection portions 45 on two straight lines are connected, or one connection portion 45 is shared by two straight lines. On the other hand, in the slit region S1 closest to the bus bar 9 side, the two connection portions 45 on two straight lines are separated from each other. However, different from the illustrated example, in the slit region S1 closest to the electrode finger 11 side, the two connection portions 45 in a linear shape may be separated from each other. In the slit region S1 closest to the bus bar 9 side, the two connection portions 45 in a linear shape may be connected to each other (or shared by two straight lines).

[0060] In addition, even if two connection portions 45 on two straight lines are separated from each other in the slit region S1 closest to the electrode finger 11, it may be considered that a V shape that closes on the electrode finger 11 side is formed as long as the distance between the two connection portions 45 is not large. For example, when the size of the gap between the two connection portions 45 closest to the electrode finger 11 side (or the distance between the geometric centers) is 1.5p or less, 1.0p or less, or 0.7p or less, it may be considered that a V shape that closes on the electrode finger 11 side is formed. The same applies to the case where a V shape that closes on the bus bar 9 side is formed. Moreover, in an aspect in which a plurality of V shapes are repeatedly arranged in the D1 direction, it is also applicable to the case where the V shapes are considered to be connected to each other.

[0061] In an embodiment in which a plurality of connection portions 45 are arranged along a straight line (or a curve) inclined with respect to the D2 direction, the positions in the D1 direction of the connection portion 45 located closest to the electrode fingers 11 and the connection portion 45 located closest to the busbar 9 may be set appropriately. For example, the connection portion 45 located closest to the electrode fingers 11 may be located at a position in the D1 direction of the electrode fingers 11 of the comb-tooth electrode 7 to which it belongs (see the center side in the left-right direction in FIG. 3A), or may be located at a position in the D1 direction of the electrode fingers 11 of another comb-tooth electrode 7 (example in FIG. 2), or may be located at any position between the former position and the latter position. The same applies to the connection portion 45 located closest to the busbar 9.

[0062] In an embodiment in which multiple connection portions 45 are arranged along a straight line (or curve) inclined with respect to direction D2, the inclination angle of the straight line may be set appropriately. From another perspective, the size of the V-shape in direction D1 may be set appropriately. From yet another perspective, the distance (relative position) in direction D1 between connection portion 45 located closest to electrode finger 11 on the straight line and connection portion 45 located closest to bus bar 9 may be set appropriately. From yet another perspective, the pitch of the arrangement of the multiple V-shapes may be set appropriately.

[0063] For example, the arrangement range of a straight line or a V-shape in the D1 direction is considered based on a line connecting the geometric centers of a plurality of connection parts 45 arranged in a straight line (or curved line) (the same applies when explaining the arrangement range of a straight line or a V-shape in other specific examples). In this case, the arrangement range of one straight line in the D1 direction may be 0.1p or more or 0.2p or more, and may be 2.0p or less, 1.5p or less, or 1.2p or less. The above lower limit and upper limit may be combined in any way. In the example of FIG. 2, the arrangement range of one straight line in the D1 direction is approximately 1p (for example, 0.8p or more and 1.2p or less). From another perspective, in the example of FIG. 2, the arrangement range of a V-shape in the D1 direction is approximately 2p (for example, 1.8p or more and 2.2p or less).

[0064] Focus on the edge on the -D1 side or +D1 side of the multiple connection parts 45 arranged in a straight line (or curved line). In this case, the edge is located, for example, on the same straight line (or on the same curve) inclined in the D1 direction (not in a stepped shape as in FIG. 4C). In other words, the edge on the -D1 side and / or the edge on the +D side of the multiple connection parts 45 are configured as if they are smoothly connected to each other (strictly speaking, the bar electrode 43 is interposed). Note that in any embodiment in which the arrangement of the multiple connection parts 45 forms a V-shape or other shape, the edge on the -D1 side and / or the edge on the +D side may or may not be configured as if they are smoothly connected to each other.

[0065] In the multiple connection parts 45 arranged in a straight line (or curved line), adjacent connection parts 45 may partially overlap each other in the D2 direction (see the example of FIG. 2), or may not overlap each other (see FIGS. 4A and 4E). In the former case, the amount of overlap is arbitrary, and may be smaller than, equal to, or larger than half the length of one connection part 45 in the D1 direction. In the latter case, the distance between two connection parts 45 is arbitrary, and may be 0 (see the example of FIGS. 4A and 4E) or larger than 0, for example.

[0066] (Second example of IDT electrode) The intermediate electrode 41B (IDT electrode 5B) shown in FIG. 3A has a plurality of connection parts 45 arranged in a V-shape, similar to the intermediate electrode 41A in FIG. 2. However, in the intermediate electrode 41B, the size of the V in the D1 direction is smaller than that of the intermediate electrode 41A. From another perspective, the number of V-shapes repeatedly arranged within a predetermined length range in the D1 direction is increased. Specifically, in the intermediate electrode 41B, the arrangement range of one straight line in the D1 direction is approximately 0.5p (e.g., 0.3p or more and 0.7p or less). From another perspective, in the example of FIG. 3A, the arrangement range of the V in the D1 direction is approximately 1p (e.g., 0.8p or more and 1.2p or less).

[0067] (Third example of IDT electrodes) In the intervening electrode 41C (IDT electrode 5C) shown in FIG. 3B, the multiple connection parts 45 are arranged in a Y-shape that opens toward the electrode finger 11. As shown in this example, the multiple connection parts 45 may include two or more connection parts 45 arranged in a straight line parallel to the D2 direction. Regarding the intervening electrode 41C, the multiple connection parts 45 (the number of which is smaller than the number of slit regions S1) located on the electrode finger 11 side may be considered to be arranged in a V-shape that opens toward the electrode finger 11. Therefore, the description of the V-shape in the intervening electrode 41A may be appropriately applied to the V-shape of the Y-shape of the intervening electrode 41C. The ratio between the number of slit regions S1 constituting the V-shaped portion of the Y-shape and the number of slit regions S1 constituting the I-shaped portion of the Y-shape is arbitrary.

[0068] (Fourth example of IDT electrodes) In an IDT electrode 5C shown in Fig. 3C, a plurality of electrode fingers 11 extend with a constant width over its entire length. In the example of Fig. 3C, the intervening electrode 41 is exemplified by the intervening electrode 41A of Fig. 2. However, the electrode fingers 11 extending with a constant width over their entire length may be combined with other specific examples of the intervening electrode 41. Similarly, the electrode fingers 11 having the widened portion 11b may be combined with any specific example of the intervening electrode 41.

[0069] (5th example of IDT electrode) 3D has so-called dummy electrodes 25. The multiple dummy electrodes 25 extend from the intervening electrode 41 (more specifically, the bar electrode 43 closest to the electrode finger 11) in parallel with the multiple electrode fingers 11. The tip of the dummy electrode 25 of one comb-tooth electrode 7 faces the tip of the electrode finger 11 of the other comb-tooth electrode 7 across a gap G1.

[0070] The shape of the dummy electrode 25 may be set appropriately. In the illustrated example, the shape of the dummy electrode 25 is a shape that protrudes in a direction perpendicular to the propagation direction of the elastic wave with a substantially constant width. In the illustrated example, the width of the dummy electrode 25 is the same as the width of the electrode finger 11 that does not have the widened portion 11b (or the width of the main portion 11a of the electrode finger 11 that has the widened portion 11b).

[0071] Unlike the illustrated example, the width of the dummy electrode 25 may be partially widened on the gap G1 side and / or the bus bar 9 side. The electrode fingers 11 and the dummy electrodes 25 may be combined with or without the widened portion. For example, in addition to the illustrated example, a combination of the electrode fingers 11 having a widened portion and the dummy electrodes 25 not having a widened portion, a combination of the electrode fingers 11 having a widened portion and the dummy electrodes 25 having a widened portion, or a combination of the electrode fingers 11 not having a widened portion and the dummy electrodes 25 having a widened portion may be adopted. In the combination of the electrode fingers 11 having a widened portion and the dummy electrodes 25 not having a widened portion, the width of the dummy electrode 25 may be, for example, equal to the width of the main portion 11a or equal to the width of the widened portion 11b.

[0072] 3D, the intervening electrode 41A in FIG. 2 is illustrated as the intervening electrode 41. However, the dummy electrode 25 may be combined with other specific examples of the intervening electrode 41. Similarly, the embodiment without the dummy electrode 25 may be applied to any specific example of the intervening electrode 41.

[0073] (Sixth example of IDT electrode) In the intervening electrode 41F (IDT electrode 5F) shown in FIG. 4A, the multiple connection parts 45 are arranged in a straight line inclined in the D2 direction, similar to the intervening electrode 41A in FIG. 2. However, the multiple connection parts 45 are arranged in a V shape that opens to one side in the D1 direction (the right side in FIG. 4A) instead of a V shape that opens to the electrode finger 11 side. From another perspective, the multiple connection parts 45 are arranged along two straight lines that incline to opposite sides with respect to the D2 direction and intersect with each other. The direction in which the V shape opens may be the same for a pair of comb-tooth electrodes 7 (as in the illustrated example) or may be different. Although not particularly illustrated, the multiple connection parts 45 may be arranged along three or more straight lines (zigzag paths) that intersect in sequence. Two connection parts 45 are located at the position where the straight lines intersect, but only one connection part 45 may be located there.

[0074] The length and / or inclination angle of two (or more) straight lines formed by the multiple connection parts 45 may be equal to each other (as in the illustrated example) or may be different from each other. As described in the description of the intervening electrode 41A, the edges of the multiple connection parts 45 arranged in a straight line on the -D1 side or +D1 side may be located on the same straight line (may be smoothly connected) or may not be located on the same straight line. In the example of FIG. 4A, the latter is adopted, and the edges of the multiple connection parts 45 are stepped. As described in the description of the intervening electrode 41A, in the multiple connection parts 45 arranged in a straight line, adjacent connection parts 45 may or may not overlap each other partially in the D2 direction. In the example of FIG. 4A, the latter is adopted, and more specifically, adjacent connection parts 45 are adjacent to each other when projected in the D1 direction (the distance between them is 0).

[0075] (7th example of IDT electrode) 4B, the multiple connection portions 45 are arranged in a checkerboard pattern. From another perspective, the multiple connection portions 45 are arranged in a plurality of straight lines parallel to each other and inclined in the D2 direction, and the multiple straight lines partially overlap each other in the D2 direction.

[0076] (8th example of IDT electrode) In the intervening electrode 41H (IDT electrode 5H) shown in Fig. 4C, the multiple connection portions 45 are arranged in multiple straight lines parallel to each other and inclined with respect to the direction D2. However, unlike Fig. 4B, the multiple straight lines have different arrangement ranges in the direction D1 and do not overlap each other in the direction D2.

[0077] (9th example of IDT electrode) The intervening electrode 41I (IDT electrode 5I) shown in Fig. 4D has a configuration generally similar to that of the intervening electrode 41H in Fig. 4C. That is, the multiple connection portions 45 are arranged in multiple straight lines parallel to each other and inclined with respect to the direction D2 (extension direction of the electrode fingers 11). However, while the straight lines of one comb-tooth electrode 7 and the straight lines of the other comb-tooth electrode 7 incline in opposite directions with respect to the direction D2 in Fig. 4C, the straight lines of one comb-tooth electrode 7 and the straight lines of the other comb-tooth electrode 7 incline in the same direction with respect to the direction D2 in Fig. 4D.

[0078] (10th example of IDT electrode) Intermediate electrode 41J (IDT electrode 5J) shown in Fig. 4E has a configuration generally similar to that of intermediate electrode 41H in Fig. 4C. That is, multiple connection portions 45 are arranged in multiple straight lines parallel to each other and inclined with respect to direction D2 (extension direction of electrode fingers 11). However, unlike intermediate electrode 41H, the multiple straight lines of intermediate electrode 41J partially overlap each other in the D2 direction, but not to the extent of a checkerboard pattern (see intermediate electrode 41G in Fig. 4B).

[0079] (11th example of IDT electrode) In the intervening electrode 41K (IDT electrode 5K) shown in FIG. 5, a region (a region where no conductor is arranged) surrounded by the connecting parts 45 adjacent to each other in each slit region S1 and the bar electrodes 43 on both sides of each slit region S1 is referred to as an opening region 47. At least one of the multiple opening regions 47 (all in the illustrated example) has an elliptical shape. Note that the ellipse here does not have to be an ellipse defined mathematically. For example, when the edges on both sides in the D1 direction are curved and bulge outward, it may be considered to be an ellipse. Typically, an ellipse is, for example, a shape obtained by squashing a circle in the D2 direction. A circle may also be included in the ellipse. A shape obtained by bulging the short side of a rectangle in a curved shape outward may also be included in the ellipse here. Here, an example is taken in which multiple connecting parts 45 are arranged in a V-shape, as in the intervening electrode 41A in FIG. 2. However, the elliptical opening region 47 may be applied to other aspects.

[0080] (others) The multiple connection parts 45 may be arranged in various ways other than the illustrated example. For example, the multiple connection parts 45 may be arranged in an X-shape. As already mentioned, the multiple connection parts 45 may be arranged along a curve.

[0081] (Speed ​​profile) Returning to FIG. 1, in a plan view of the top surface 3a of the piezoelectric body 3, the region in which the IDT electrodes 5 are arranged can be divided into the following four regions in the direction D2 based on the configuration of the IDT electrodes 5: an intersection region R0 in which multiple first electrode fingers (electrode fingers 11 of one comb-tooth electrode 7) and multiple second electrode fingers (electrode fingers 11 of the other comb-tooth electrode 7) overlap in the acoustic wave propagation direction; a gap region RG in which the gap G1 is located; an intermediate region RI in which the intermediate electrode 41 is located; and a busbar region RB in which the busbar 9 is located.

[0082] The intersection region R0 may be regarded as a region sandwiched between a line (not shown) connecting the tips of the electrode fingers 11 of one comb-tooth electrode 7 and a line (not shown) connecting the tips of the electrode fingers 11 of the other comb-tooth electrode 7. When a line connecting predetermined portions (e.g., tips) of a plurality of electrode fingers 11 is assumed, if the position of the line differs depending on which position within the width of electrode finger 11 is used as the reference, the center line of electrode finger 11 may be used as the reference.

[0083] In the illustrated example, the intersection region R0 can be divided into the following two (three) regions in the D2 direction based on the width of the electrode fingers 11: A central region RC where multiple main portions 11a overlap each other in the D1 direction; and an edge region RE where multiple widened portions 11b overlap each other in the D2 direction. For details about these widths (in the D2 direction), please refer to the descriptions of the main portions 11a and the widened portions 11b.

[0084] These multiple regions have different sound velocities. The sound velocity here may be, for example, the speed at which an elastic wave of a mode used by the device 1 propagates through the piezoelectric body 3. However, in a case where multiple regions are defined based on the shape of the IDT electrode 5 or the like, the relationship between the high and low sound velocities of the multiple regions is not usually reversed depending on the difference in the specific mode of the elastic wave used. Therefore, when considering the relationship between the high and low sound velocities described below, it is not necessary to specify which mode of elastic wave is the sound velocities.

[0085] The sound speed of the elastic wave is affected by the mass of the member (e.g., the IDT electrode 5) located on the upper surface 3a of the piezoelectric body 3. For example, in each region, the greater the mass per unit area, the lower the sound speed. On the other hand, when the thickness of the conductor layer constituting the IDT electrode 5 is constant, the greater the ratio of the conductor layer to the unit area, the greater the mass per unit area. Therefore, the sound speed becomes lower in regions where the area ratio of the conductor layer constituting the IDT electrode 5 is greater.

[0086] Therefore, in the illustrated example, the regions are named in ascending order of sound speed, for example, the busbar region RB, the intersection region R0, and the gap region RG. In the intersection region R0, the edge region RE has a lower sound speed than the central region RC. The intervening region RI has a higher sound speed than the busbar region RB. The intervening region RI may have a lower sound speed than the intersection region R0 and the gap region RG, or may have a higher sound speed than the intersection region R0 and the gap region RG. For example, the intervening region RI has a lower sound speed than the gap region RG and the central region RC (or the intersection region R0 in a state in which the width of the electrode finger 11 is constant over the entire length).

[0087] Although not shown in particular, the sound velocity in the intersection region R0 may change in three or more stages, not just two stages. For example, the central region RC may include two or more regions with different sound velocities. The same applies to the edge region RE. Also, the change in sound velocity with respect to the position in the D2 direction may be continuous, not stepwise. The above-mentioned speed profile (the relationship between high and low speeds between regions) may be realized by a method other than the ratio of the conductor layer occupying a unit area. For example, an additional film (described later) that partially overlaps the upper surface or lower surface of the IDT electrode 5 may be provided to reduce the speed in the region where the additional film is provided. Also, the conductor layer constituting the IDT electrode 5 may be partially thickened to reduce the speed in the thickened region. Also, an insulating film may be provided at an appropriate position, regardless of whether the conductor constituting the IDT electrode 5 is provided in an area where the conductor is not provided, to reduce the speed in the region where the insulating film is provided.

[0088] (Various configuration examples of substrates including piezoelectric bodies) The piezoelectric body 3 having the upper surface 3a on which the IDT electrode 5 is formed may be, for example, a part or the whole of a substrate. The substrate may have various configurations, for example, a known configuration. The following are examples of the substrate configuration.

[0089] 6 is a cross-sectional view showing the configuration of a substrate 13A as a first example of the substrate, the cross section corresponding to the cross section taken along line VI-VI in FIG.

[0090] Substrate 13A has, for example, support substrate 15, intermediate layer 17 overlapping the upper surface of support substrate 15, and piezoelectric body 3 overlapping the upper surface of intermediate layer 17. Here, piezoelectric body 3 is configured as a piezoelectric film. In the description of the configuration of the elastic wave device, the terms "plate," "layer," and "film" are used interchangeably unless otherwise specified. The thickness of each layer is constant, for example, regardless of the position in the planar direction (direction parallel to the D1-D2 plane).

[0091] The piezoelectric body 3 is made of, for example, a single crystal having piezoelectricity. Examples of materials that make up such a single crystal include lithium tantalate (LiTaO 3 Hereinafter, it may be abbreviated as LT. ), lithium niobate (LiNbO 3 Hereinafter, this may be abbreviated as LN.) and quartz (SiO 2 ) can be mentioned. The piezoelectric body 3 may be made of polycrystal. The cut angle, planar shape and various dimensions of the piezoelectric body 3 may be set appropriately. For example, a piezoelectric body made of LT or LN may be a rotated Y cut X-propagation type. That is, the propagation direction of the elastic wave (D1 direction) and the X-axis may be approximately the same (for example, the difference between the two is ±10°). In this case, the inclination angle of the Y-axis with respect to the normal line (D3 direction) of the upper surface 3a of the piezoelectric body 3 may be set appropriately. The thickness of the piezoelectric body 3 may be, for example, 0.1p or more or 0.3p or more, and may be 2p or less or 1p or less. The upper and lower limits may be combined appropriately.

[0092] The support substrate 15 may contribute to at least one of improving the strength of the substrate 13A, compensating for changes in characteristics caused by temperature changes (temperature compensation), and confining elastic waves in the piezoelectric body 3. The improvement in strength may be achieved, for example, by appropriately setting the thickness of the support substrate 15 made of a material having a certain degree of strength. The temperature compensation may be achieved, for example, by making the linear expansion coefficient of the support substrate 15 smaller than the linear expansion coefficient of the piezoelectric body 3. The confinement of elastic waves may be achieved, for example, by making the sound velocity of the support substrate 15 higher than the sound velocity of the piezoelectric body 3 (and / or the intermediate layer 17) and / or by making the acoustic impedance of the support substrate 15 different from the acoustic impedance of the intermediate layer 17.

[0093] The material and thickness of the support substrate 15 may be appropriately set in consideration of the above-mentioned purpose. For example, the material of the support substrate 15 may be a semiconductor such as silicon (Si), sapphire (Al 2 O 3 ) or other single crystals or sintered aluminum oxide (Al 2 O 3 The support substrate 15 may be made of a ceramic such as a ferroelectric material. The support substrate 15 has a thickness of, for example, 1p or more or 3p or more. The support substrate 15 has a thickness greater than that of the piezoelectric body 3, for example.

[0094] The intermediate layer 17 may contribute to at least one of, for example, improving the bonding strength between the piezoelectric body 3 and the support substrate 15 and confining elastic waves in the piezoelectric body 3. The improvement of the bonding strength may be achieved, for example, by selecting, as the material of the intermediate layer 17, a material that has a relatively high bonding strength between the piezoelectric body 3 and the support substrate 15 when a predetermined bonding method is used. The confinement of elastic waves may be achieved, for example, by the sound velocity of the intermediate layer 17 being lower than the sound velocity of the piezoelectric body 3 (and / or the support substrate 15) and / or by the acoustic impedance of the intermediate layer 17 being different from the acoustic impedance of the piezoelectric body 3 (and / or the support substrate 15).

[0095] The material and thickness of the intermediate layer 17 may be appropriately set in consideration of the above-mentioned purpose. For example, the material of the intermediate layer 17 is silicon oxide (SiO 2) The thickness of the intermediate layer 17 may be, for example, 0.01p or more or 0.1p or more, and may be 2p or less, 1p or less, or 0.5p or less. The above upper and lower limits may be appropriately combined. The thickness of the intermediate layer 17 is, for example, thinner than the thickness of the support substrate 15. The thickness of the intermediate layer 17 may be thinner, equal to, or thicker than the thickness of the piezoelectric body 3.

[0096] As described above, the intermediate layer 17 may be a low acoustic velocity layer having a lower acoustic velocity than the piezoelectric body 3, while the support substrate 15 may be a high acoustic velocity layer having a higher acoustic velocity than the piezoelectric body 3. This can reduce, for example, elastic waves leaking from the piezoelectric body 3.

[0097] The sound velocity here may be, for example, a shear wave sound velocity determined by the physical properties of each material itself. In other words, unlike the sound velocity described in the velocity profile in the arrangement region of the IDT electrode 5, the influence of the IDT electrode 5 may be ignored. The shear wave sound velocity is obtained by the square root of the value obtained by dividing the elastic modulus by the density. However, the sound velocity of the piezoelectric body 3 compared with the sound velocity of the intermediate layer 17 and the support substrate 15 may be the sound velocity in the central region RC (intersection region R0 in a mode in which the width of the electrode fingers 11 is constant over the entire length) of the elastic wave of the mode to be used, instead of the shear wave sound velocity. In addition, the sound velocity of the intermediate layer 17 and / or the support substrate 15 may be the sound velocity of the bulk wave of the mode that has a relatively large effect on the leakage of the energy of the elastic wave of the mode to be used.

[0098] The material of the intermediate layer 17 as the low acoustic velocity layer and the material of the support substrate 15 as the high acoustic velocity layer may be combined in any manner. For example, the combination of these materials may be the above-mentioned SiO 2 and Si. When the intermediate layer 17 is provided as a low acoustic velocity layer, a layer for improving the bonding strength between the intermediate layer 17 and the piezoelectric body 3 and / or a relatively thin layer for improving the bonding strength between the intermediate layer 17 and the support substrate 15 may be provided.

[0099] 7 is a cross-sectional view showing the configuration of a substrate 13B as a second example of the substrate, the cross section corresponding to the cross section taken along line VI-VI in FIG.

[0100] The substrate 13B is the substrate 13A described above, but with a multilayer film 19 instead of the intermediate layer 17. The multilayer film 19 has two or more layers (six layers in the illustrated example) of acoustic films (first film 21A and second film 21B). The materials of the acoustic films adjacent to each other in the stacking direction (overlapping each other without any other acoustic film in between) are different from each other. From another point of view, the acoustic impedances of the adjacent acoustic films are different from each other. This makes the reflectance of the elastic wave relatively high at the interface between the two, for example. As a result, for example, the leakage of the elastic wave propagating through the piezoelectric body 3 is reduced. The combination of the intermediate layer 17 and the support substrate 15 in the substrate 13A in FIG. 6 may be regarded as a kind of multilayer film. In the substrate 13B in FIG. 7, the multilayer film may be defined to include the support substrate 15.

[0101] The number of types of materials for the acoustic membranes of the multilayer film 19 and the number of acoustic membranes may be set appropriately. In the illustrated example, two types of acoustic membranes (first membrane 21A and second membrane 21B) are alternately laminated in three or more layers (more specifically, six layers). The material of the acoustic membranes may also be arbitrary. For example, the material of the first membrane 21A is silicon dioxide (SiO 2 The material of the second film 21B may be tantalum pentoxide (Ta 2 O 5 ), hafnium oxide (HfO 2 ), zirconium dioxide (ZrO 2 ), titanium dioxide (TiO 2 ), magnesium oxide (MgO) or silicon nitride (Si 3 N 4 In this case, the first film 21A has a lower acoustic impedance than the second film 21B, for example. The thickness of the acoustic film may be set appropriately, and for example, the above description of the thickness of the intermediate layer 17 may be used.

[0102] The acoustic films (first film 21A and second film 21B) may be configured with a low acoustic velocity film and a high acoustic velocity film, similar to the intermediate layer 17 and the support substrate 15 of the substrate 13A in FIG. 6. For example, the first film 21A may be made of a material (e.g., SiO 2 Or Ta 2 O 5 The second film 21B may be made of a material having a higher sound velocity than the piezoelectric body 3 (e.g., Si 3 N 4 ) may be considered.

[0103] Although not particularly shown, the substrate including the piezoelectric body 3 may be in various forms other than the above examples. For example, the substrate may be substantially entirely composed of the piezoelectric body 3. From another point of view, the piezoelectric body 3 may be relatively thick. The substrate may have a cavity below the relatively thin (for example, 2p or less or 1p or less) piezoelectric body 3. The substrate may have a high acoustic velocity layer overlapping the lower surface of the intermediate layer 17 as the low acoustic velocity layer, separate from the support substrate 15, in the substrate 13A of FIG. 6. Contrary to the explanation of the substrates 13A and 13B, the high acoustic velocity layer may overlap the lower surface of the piezoelectric body 3 to realize the confinement of the elastic wave.

[0104] (Other Configurations of Elastic Wave Device) Although not shown in the figures, the acoustic wave device 1 may have an insulating protective film that covers the upper surface 3a of the piezoelectric body 3 from above the conductor layer including the IDT electrode 5. The protective film may contribute to reducing corrosion of the conductor layer and / or contribute to temperature compensation, for example. Examples of materials for the protective film include SiO 2 , Si 3 N 4 and Si. The protective film may be a laminate of these materials.

[0105] Furthermore, the device 1 may have an additional film overlapping the upper or lower surface of the IDT electrode 5. The additional film, for example, overlaps the entire or part of the IDT electrode 5 and has a shape that fits within the IDT electrode 5 in a planar perspective view. Such an additional film is made of, for example, an insulating material or a metal material that has acoustic properties different from those of the material of the IDT electrode 5, and contributes to improving the reflection coefficient of the acoustic wave.

[0106] The device 1 may be packaged as appropriate. Examples of package configurations include the following: A package in which the substrate 13A (or 13B, etc.) is mounted on a substrate (not shown) with a gap between them so that the top surface 3a of the piezoelectric element 3 faces the substrate, and then sealed with molding resin from above; or a wafer-level package in which a box-shaped cover that covers the top surface 3a is provided on the substrate 13A (or 13B, etc.).

[0107] (Summary of Elastic Wave Devices) As described above, the acoustic wave device 1 includes a piezoelectric body 3 and an IDT electrode 5. The piezoelectric body 3 has a first surface (upper surface 3a). The IDT electrode 5 is located on the upper surface 3a. The IDT electrode 5 includes the following components: a first busbar (busbar 9 of one comb-tooth electrode 7); a second busbar (busbar 9 of the other comb-tooth electrode 7) facing the first busbar; a plurality of first electrode fingers (electrode fingers 11 of one comb-tooth electrode 7) electrically connected to the first busbar; a plurality of second electrode fingers (electrode fingers 11 of the other comb-tooth electrode 7) electrically connected to the second busbar and arranged alternately with the plurality of first electrode fingers in the acoustic wave propagation direction (direction D1); and a plurality of bar electrodes 43 (here, the bar electrodes 43 of one comb-tooth electrode 7 are taken as an example) interposed between the first busbars and between the plurality of first electrode fingers, extending in parallel to the first busbar and extending in parallel to each other. A plurality of (at least two) connection parts 45 including a connection part 45 interposed between the first bus bar and a bar electrode 43 adjacent to the first bus bar to connect them, and a connection part 45 interposed between adjacent bar electrodes 43 to connect them. At least some of the plurality of connection parts 45 are arranged discontinuously with respect to the extension direction (direction D2) of the plurality of electrode fingers 11.

[0108] Therefore, for example, as described above, the reflection positions of the spurious in the transverse mode can be dispersed compared to the embodiment in which the multiple connection parts 45 are continuously arranged in the D2 direction. As a result, the wavelengths of the spurious in the transverse mode and the positions of the nodes and antinodes can be dispersed, and the constructive interaction of the spurious in the transverse mode can be reduced. As a result, the spurious can be reduced.

[0109] The multiple connection portions 45 may be arranged in a direction inclined with respect to the extending direction (direction D2) of the electrode fingers 11 (FIGS. 2 to 5).

[0110] In this case, for example, the reflection position around the connection portion 45 is located on the +D2 side or the -D2 side as it is located on one side in the D1 direction. This makes it possible to reliably and efficiently disperse the reflection positions of the transverse mode spurious and reduce the reinforcement of the transverse mode spurious. In particular, if multiple connection portions 45 are arranged obliquely from the bar electrode 43 closest to the electrode finger 11 to the bus bar 9, the above effect is improved.

[0111] The multiple connection portions 45 may be arranged in a V shape closing toward the multiple electrode fingers 11 (FIG. 2, and FIGS. 3A to 3D).

[0112] In this case, for example, two straight lines inclined in the D2 direction formed by the arrangement of the multiple connection parts 45 intersect, so it is easier to obtain the effect of dispersing the reflection positions without any gaps in the D1 direction compared to an embodiment in which the two straight lines are separated from each other. As a result, the effect of reducing the spurious of the transverse mode is improved.

[0113] The multiple connection portions 45 may be arranged in a Y shape that opens toward the multiple electrode fingers 11 (FIG. 3B).

[0114] In this case, for example, the Y-shape includes a V-shape, so the same effect as above can be achieved. Also, for example, the size of the V-shape included in the Y-shape in the D2 direction can be adjusted. The bar electrodes 43 remaining as a result of the adjustment are maintained at the same potential by the I-shape included in the Y-shape.

[0115] In a plan view of the upper surface 3a of the piezoelectric body 3, the region in which the IDT electrode 5 is located may include the following regions: a busbar region RB in which the busbar 9 is located; an intervening region RI in which the bar electrodes 43 and the connection portions 45 are located; a gap region RG in which a gap G1 is located adjacent to the tips of the second electrode fingers (the electrode fingers 11 of the comb-tooth electrode 7 that mesh with the comb-tooth electrode 7 to which the intervening electrode 41 of interest belongs) on the side of the intervening region RI; an intersection region R0 in which the electrode fingers 11 of a pair of comb-tooth electrodes 7 overlap in the acoustic wave propagation direction (direction D1). The intersection region R0 may also include the following regions: a central region RC located at the center of the intersection region R0 in the D2 direction, and having a lower sound speed than the gap region RG; and an edge region RE located between the central region RC and the gap region RG, and having a lower sound speed than the central region RC. The intermediate region RI may have a higher sound speed than the busbar region RB.

[0116] In this case, for example, the use of the piston mode reduces the spurious in the transverse mode, so that the spurious in the transverse mode can be further reduced. Furthermore, if the sound speed in the intermediate region RI is lower than that in the busbar region RB, the intermediate electrode 41 functions similarly to the busbar 9, and the significance of providing the intermediate electrode 41 between the busbar 9 and the gap region RG is reduced. In addition, the effect of dispersing the reflection positions of the spurious in the transverse mode is reduced. However, such a disadvantage is reduced by making the sound speed in the intermediate region RI higher than that in the busbar region RB.

[0117] The edges of the multiple connection portions 45 located on one side (the +D1 side or the -D1 side) of the elastic wave propagation direction may be located on the same straight line or curve inclined with respect to the extension direction (the D2 direction) of the electrode fingers 11 (Figures 2 to 3D).

[0118] In this case, for example, compared to the embodiment in which the above-mentioned edges are parallel to the D2 direction (FIGS. 4A to 4E), the edges of each connection portion 45 can define the reflection position of the spurious in the transverse mode, and the position can be changed in the D2 direction depending on the position in the D1 direction. As a result, the effect of reducing spurious is improved.

[0119] Two or more connection parts 45 having different positions in the elastic wave propagation direction (D1 direction) may be located between adjacent bar electrodes 43 (in each slit region S1). The shape of a region (opening region 47) surrounded by the two or more connection parts 45 and the bar electrodes 43 connected by the two or more connection parts 45 may be elliptical.

[0120] In this case, for example, the edge of one of the aperture regions 47 can define a reflection position of the spurious in the transverse mode, and the position can be changed in the D2 direction depending on the position in the D1 direction. As a result, the effect of reducing the spurious is improved.

[0121] The device 1 may further include a plurality of dummy electrodes 25. The plurality of dummy electrodes 25 may be connected to a bar electrode 43 (bar electrode 43 having the same potential as the first electrode fingers) located closest to the plurality of first electrode fingers (electrode fingers 11 of one comb-tooth electrode 7), and their tips may face tips of the plurality of second electrode fingers (electrode fingers 11 of the other comb-tooth electrode 7) across a gap G1.

[0122] In this case, for example, it is easy to adjust the distance between the gap G1 and the intervening electrode 41. The gap G1 is a portion where diffraction of an elastic wave occurs and affects the spurious of the transverse mode, so that the spurious can be easily reduced by adjusting the distance. In addition, for example, the spurious of the transverse mode can be reduced by apodizing the IDT electrode 5, which changes the position of the gap G1 in the D2 direction relative to the position in the D1 direction while keeping the size of the gap G1 constant.

[0123] The acoustic wave device 1 may further include a low acoustic velocity film (intermediate layer 17 in FIG. 6 or first film 21A in FIG. 7) and a high acoustic velocity film (support substrate 15 in FIG. 6 or second film 21B in FIG. 7). The low acoustic velocity film overlaps the side opposite to the top surface 3a of the piezoelectric body 3 made of a piezoelectric film, and has a lower acoustic velocity than the piezoelectric body 3. The high acoustic velocity film overlaps the side opposite to the low acoustic velocity film and the piezoelectric body 3, and has a higher acoustic velocity than the piezoelectric body 3.

[0124] In this case, for example, it is possible to reduce the elastic waves leaking from the piezoelectric body 3. As a result, the characteristics of the device 1 are improved.

[0125] <Examples of using elastic wave devices> The acoustic wave device 1 may be used in various aspects such as a resonator and a filter. Examples of uses of the acoustic wave device are described below. Specifically, the following description will be given in the following order. An example of a resonator An example of a splitter An example of a communication device

[0126] A resonator, a duplexer, and a communication device are all examples of applications of an acoustic wave device. In the description of the duplexer, a filter will also be described as an example of an application of an acoustic wave device.

[0127] (An example of a resonator) Fig. 8 is a plan view showing the configuration of the resonator 31. In the following description, for the reference numerals relating to the IDT electrodes 5, please refer to Fig. 1 and the like.

[0128] The resonator 31 is configured as a so-called one-port acoustic wave resonator. When an electrical signal of a predetermined frequency is input to one of two terminals 33 conceptually and diagrammatically shown in FIG. 8, the resonator 31 resonates and can output the signal that has generated the resonance from the other of the two terminals 33.

[0129] The resonator 31 has, for example, a piezoelectric body 3 (see FIG. 6 and the like), as well as an IDT electrode 5 and a pair of reflectors 35 located on an upper surface 3a of the piezoelectric body 3. The resonator 31 may be considered to include the acoustic wave device 1, or may be considered to be included in the device 1. As described above, the resonator 31 includes the piezoelectric body 3 (and other layers that affect acoustic waves). However, for convenience, the combination of the IDT electrode 5 and the pair of reflectors 35 may be expressed as the resonator 31.

[0130] The pair of reflectors 35 are formed, for example, by the same conductor layer as the conductor layer forming the IDT electrode 5. In a mode in which an additional film overlapping all or part of the IDT electrode 5 is provided, an additional film overlapping all or part of the reflector 35 may be provided. The pair of reflectors 35 are located on both sides of the IDT electrode 5 in the propagation direction of the acoustic wave. Each reflector 35 may be, for example, in an electrically floating state, or may be given a reference potential.

[0131] Each reflector 35 is formed, for example, in a lattice shape. That is, the reflector 35 includes a pair of bus bars 37 facing each other and a plurality of strip electrodes 39 extending between the pair of bus bars 37. Note that, like the plurality of electrode fingers 11, the plurality of strip electrodes 39 may actually be provided in greater number than the number shown in the figure.

[0132] Busbar 37 has, for example, a configuration generally similar to busbar 9 of IDT electrode 5, and the description of busbar 9 may be applied to busbar 37. The position of busbar 37 in direction D2 may be, for example, an appropriate position outside gap region RG. In the illustrated example, busbar 37 is located within the arrangement range of intervening electrode 41 in direction D2. The width (direction D2) of busbar 37 may be smaller, equal to, or larger than the width of busbar 9. When busbar 9 is inclined in the propagation direction of the elastic wave, busbar 37 may be inclined in the same manner as busbar 9, or may be parallel to the propagation direction of the elastic wave.

[0133] The schematic configuration of the multiple strip electrodes 39 is similar to that of the electrode fingers 11 of the IDT electrode 5, except that the multiple strip electrodes 39 are bridged across a pair of bus bars 37. The description of the electrode fingers 11 may be applied to the strip electrode 39 as appropriate. The multiple strip electrodes 39 are arranged in the propagation direction of the acoustic wave so as to follow the arrangement of the multiple electrode fingers 11. The pitch of the multiple strip electrodes 39 and the pitch between the electrode fingers 11 adjacent to the reflector 35 and the strip electrode 39 adjacent to the IDT electrode 5 are, for example, equal to the pitch of the multiple electrode fingers 11.

[0134] The specific planar shape of the strip electrode 39 (or, from another perspective, the change in width (length in the D1 direction) depending on the position in the D2 direction) is arbitrary. In the example shown, the strip electrode 39 has a main portion 39a and a widened portion 39b, similar to the electrode finger 11. The main portion 39a overlaps with the main portion 11a of the electrode finger 11 in the D2 direction. The widened portion 39b overlaps with the widened portion 39b of the electrode finger 11 in the D2 direction. The explanation of the main portion 11a and the widened portion 11b may be applied to the main portion 39a and the widened portion 39b.

[0135] In the illustrated example, the reflector 35 does not have a structure corresponding to the intermediate electrode 41. However, the reflector 35 may have a structure corresponding to the intermediate electrode 41.

[0136] (An example of a splitter) 9 is a circuit diagram showing a schematic configuration of a branching filter 101 (e.g., a duplexer). As can be seen from the reference numerals in the upper left corner of the figure, in this figure, the comb-tooth electrode 7 is shown in a schematic form with a two-pronged fork shape, and the reflector 35 is represented by a single line bent at both ends.

[0137] The splitter 101 has, for example, a transmit filter 109 that filters a transmit signal from the transmit terminal 105 and outputs the signal to the antenna terminal 103, and a receive filter 111 that filters a receive signal from the antenna terminal 103 and outputs the signal to a pair of receive terminals 107.

[0138] The transmit filter 109 is configured, for example, as a ladder filter configured by connecting a plurality of resonators 31 (series resonators 31S and parallel resonators 31P) in a ladder configuration. That is, the transmit filter 109 has a plurality of series resonators 31S (or one) connected in series between the transmit terminal 105 and the antenna terminal 103, and a plurality of parallel resonators 31P (or one) connecting the series line (series arm) and a reference potential section (reference symbol omitted).

[0139] The receiving filter 111 is configured to include, for example, a resonator 31 and a multimode filter (including a double-mode filter) 113. The multimode filter includes a double-mode filter. The multimode filter 113 has a plurality of IDT electrodes 5 (three in the illustrated example) arranged in the propagation direction of the acoustic wave, and a pair of reflectors 35 arranged on both sides thereof.

[0140] At least one of the multiple resonators of the transmit filter 109 (ladder filter) may include the acoustic wave device 1 (IDT electrode 5) according to the embodiment. In terms of one IDT electrode 5 included in the device 1, the transmit filter 109 includes the device 1 and one or more other IDT electrodes that are located on the upper surface 3a of the piezoelectric body 3 of the device 1 and are connected in a ladder configuration with the one IDT electrode 5 to form a ladder filter (in the illustrated example, the other IDT electrodes are also the IDT electrode 5 according to the embodiment).

[0141] At least one of the multiple IDT electrodes of the multimode filter 113 may include the acoustic wave device 1 (IDT electrode 5) according to the embodiment. In terms of one IDT electrode 5 included in the device 1, the multimode filter 113 includes the device 1 and one or more other IDT electrodes (in the illustrated example, the other IDT electrodes are also the IDT electrode 5 according to the embodiment) that are located on the upper surface 3a of the piezoelectric body 3 of the device 1 and are arranged in the acoustic wave propagation direction with respect to the one IDT electrode 5 to form a multimode filter.

[0142] In addition, each of the splitter 101, the transmit filter 109 (ladder type filter), the receive filter 111 and the multi-mode filter 113 may be considered to include the device 1 of the embodiment, or may be considered to be included in the device 1.

[0143] The multiple IDT electrodes 5 (and reflectors 35) of the branching filter 101 may be provided on one piezoelectric body 3 (substrate) or may be distributed across two or more piezoelectric bodies 3. For example, the multiple resonators 31 constituting the transmit filter 109 may be provided on the same piezoelectric body 3. Similarly, the resonators 31 and the multi-mode filter 113 constituting the receive filter 111 may be provided on the same piezoelectric body 3. The transmit filter 109 and the receive filter 111 may be provided on the same piezoelectric body 3 or on different piezoelectric bodies 3. In addition to the above, for example, multiple series resonators 31S may be provided on the same piezoelectric body 3, and multiple parallel resonators 31P may be provided on another same piezoelectric body 3.

[0144] 9 is merely one example of the configuration of the duplexer 101. Therefore, for example, the receiving filter 111 may be configured with a ladder filter like the transmitting filter 109. Also, the transmitting filter 109 may have a multimode filter 113. The duplexer 101 is not limited to a duplexer, and may be, for example, a diplexer or a multiplexer including three or more filters.

[0145] (Communication Equipment) 10 is a block diagram showing a main part of a communication device 151 as an example of a use of the elastic wave device 1. The communication device 151 performs wireless communication using radio waves, and includes a duplexer 101.

[0146] In the communication device 151, a transmission information signal TIS including information to be transmitted is modulated and frequency-raised (converted into a high-frequency signal having a carrier frequency) by an RF-IC (Radio Frequency Integrated Circuit) 153 to become a transmission signal TS. Unnecessary components outside the transmission passband are removed from the transmission signal TS by a bandpass filter 155, amplified by an amplifier 157, and input to a splitter 101 (transmission terminal 105). Then, the splitter 101 (transmission filter 109) removes unnecessary components outside the transmission passband from the input transmission signal TS, and outputs the transmission signal TS after removal from an antenna terminal 103 to an antenna 159. The antenna 159 converts the input electrical signal (transmission signal TS) into a wireless signal (radio wave) and transmits it.

[0147] Furthermore, in the communication device 151, a radio signal (radio wave) received by the antenna 159 is converted by the antenna 159 into an electric signal (received signal RS) and input to the duplexer 101 (antenna terminal 103). The duplexer 101 (receiving filter 111) removes unnecessary components outside the receiving passband from the inputted received signal RS and outputs it from the receiving terminal 107 to the amplifier 161. The outputted received signal RS is amplified by the amplifier 161, and the unnecessary components outside the receiving passband are removed by the bandpass filter 163. Then, the received signal RS is frequency-downgraded and demodulated by the RF-IC 153 to become a received information signal RIS.

[0148] The transmission information signal TIS and the reception information signal RIS may be low-frequency signals (baseband signals) containing appropriate information, for example, analog audio signals or digitized audio signals. The passband of the radio signal may be set appropriately and may conform to various known standards. The modulation method may be any of phase modulation, amplitude modulation, frequency modulation, or a combination of two or more of these. Although the direct conversion method is exemplified as the circuit method, other appropriate methods may be used, for example, double superheterodyne method. Also, FIG. 10 shows only the main parts in a schematic manner, and low-pass filters, isolators, etc. may be added at appropriate positions, and the positions of amplifiers, etc. may be changed.

[0149] The acoustic wave device 1 may be used in various aspects other than the above-described aspects, For example, the acoustic wave device 1 may be used in a two-port resonator or a transversal filter.

[0150] <Example> The effects of the elastic wave device 1 according to the embodiment were confirmed by measuring the characteristics of a prototype of the resonator 31 (FIG. 8) according to the embodiment and calculating the characteristics of the resonator 31 by simulation. Some examples of the results of the simulation calculations are shown below.

[0151] (First Comparative Example and First Example) FIG. 11 is a diagram showing the characteristics of the resonators according to the first comparative example and the first embodiment.

[0152] 11, the horizontal axis represents frequency. The vertical axis represents the phase of impedance. Line LC1 represents the characteristics of the first comparative example. Line LE1 represents the characteristics of the first embodiment.

[0153] The resonator 31 has a resonant frequency where the absolute value of the impedance is a minimum value, and an anti-resonant frequency where the absolute value of the impedance is a maximum value. In general, in the range between the resonant frequency and the anti-resonant frequency, the closer the phase of the impedance is to 90°, the better the characteristics of the resonator 31. Outside the above range, the closer the phase of the impedance is to -90°, the better the characteristics of the resonator 31. In FIG. 11, the range of the horizontal axis roughly corresponds to the range between the resonant frequency and the anti-resonant frequency.

[0154] In the first embodiment, the IDT electrode 5 has a configuration similar to that of the IDT electrode 5A according to the first example shown in Fig. 2. In the first comparative example, the multiple connection portions 45 in the first embodiment are eliminated. However, in each comb-tooth electrode 7, it is assumed that the multiple bar electrodes 43 and the bus bar 9 are at the same potential (electrically connected) to each other.

[0155] 11, in the first embodiment, the number and magnitude of spurious signals are reduced compared to the first comparative example. That is, it was confirmed that the spurious signals are reduced by providing the multiple connection parts 45 discontinuously in the D2 direction.

[0156] The specific conditions for the simulation calculation are shown below. Piezoelectric: Material:LT Cut angle: 50° rotation Y cut X propagation Thickness: 0.65μm ·Low sound velocity layer (middle layer 17): Material: SiO 2 Thickness: 0.22μm ·High sonic layer (support substrate 15): Material:Si Thickness: Sufficient thickness for pitch p (200 μm) ·IDT electrode: Material: Ti and Al laminated structure Thickness: Ti: 60 Å Al: 1400Å Electrode finger: Number of pieces: 250 Pitch: 1.03μm Main Duty: 0.50 Duty of widened section: 0.60 Length of one widened section (D2 direction): 1.0 μm Width of intersection area R0: 40p Length of gap G1 (D2 direction): 0.3 μm Bar electrode: Number of pieces: 8 Width (D2 direction): 0.25p Bar electrode spacing (width of slit area S1): 0.25p ·Reflector: Material and thickness: same as IDT electrode Strip Electrode: Number of pieces: 30 (1 reflector) Pitch: Same as the electrode finger pitch

[0157] (First to third examples) Fig. 12 is a diagram showing the characteristics of the resonators according to the first to third examples, and is similar to Fig. 11. In Fig. 12, line LE1 shows the characteristics of the first example, and is the same as line LE1 shown in Fig. 11. Lines LE2 and LE3 show the characteristics of the second and third examples, respectively.

[0158] In the second embodiment, the IDT electrode 5 has the same configuration as the IDT electrode 5B according to the second embodiment shown in FIG. 3A. That is, in the first embodiment, the size of the V shape in the D2 direction is approximately 2p, whereas in the second embodiment, the size of the V shape in the D2 direction is approximately 1p. In addition, the third embodiment has a configuration roughly similar to that of the IDT electrode 5C according to the third embodiment shown in FIG. 3B. However, in the I-shaped portion included in the Y-shape, the connection portion 45 is eliminated, and it is assumed that the bar electrodes 43 and the bus bars 9 are at the same potential (electrically connected to each other).

[0159] 12, the spurious response is generally reduced more in the second embodiment than in the first embodiment, and the spurious response is generally reduced more in the first embodiment than in the third embodiment. That is, the greater the change in the position of the connection portion 45 in the D2 direction relative to the position in the D1 direction, the greater the reduction in the spurious response. The first embodiment is easier to fabricate than the second embodiment.

[0160] (Second and third comparative examples and fourth embodiment) Fig. 13 is a diagram showing the characteristics of the resonators according to the second and third comparative examples and the fourth embodiment, and is similar to Fig. 11. In Fig. 13, lines LC2, LC3, and LE4 show the characteristics of the second and third comparative examples and the fourth embodiment, respectively.

[0161] The fourth embodiment has an IDT electrode 5 having the same configuration as the IDT electrode 5D according to the fourth example shown in FIG. 3C. That is, in the fourth embodiment, the width of the electrode fingers 11 in the first embodiment is constant over the entire length of the electrode fingers 11. In the second comparative example, the intermediate electrode 41 is eliminated by expanding the bus bar 9 to the arrangement area of ​​the intermediate electrode 41 in the fourth embodiment. In the third comparative example, the multiple connection portions 45 in the fourth embodiment are eliminated. However, in the fourth embodiment, it is assumed that the multiple bar electrodes 43 and the bus bar 9 of each comb-tooth electrode 7 are at the same potential (electrically connected to each other).

[0162] 13, the spurious response is generally reduced in the fourth embodiment compared to the second and third comparative examples. This confirms that even if the IDT electrode 5 does not utilize the piston mode, the spurious response can be reduced by disposing the multiple connection parts 45 discontinuously in the D2 direction.

[0163] Although not shown in particular, a simulation calculation was also performed for a comparative example in which the thickness of the busbar was thinned in the second comparative example. From another perspective, a simulation calculation was also performed for a comparative example in which the intermediate electrode 41 was not provided and the sound speed in the region corresponding to the intermediate region RI was increased. As a result, although the effect of reducing the spurious was obtained by thinning the thickness of the busbar, the effect was not as great as that of the embodiment. From this, it was confirmed that the effect of reducing spurious by the intermediate electrode 41 is an effect as a reflector against the spurious of the transverse mode. [Explanation of symbols]

[0164] 1...acoustic wave device, 3...piezoelectric body, 3a...upper surface (first surface), 5...IDT electrode, 9...bus bar (first bus bar, second bus bar), 11...electrode fingers (first electrode finger, second electrode finger), 43...bar electrode, 45...connection portion.

Claims

1. a piezoelectric body having a first surface; an IDT electrode located on the first surface, The IDT electrode is A first bus bar; a second bus bar facing the first bus bar; a plurality of first electrode fingers each electrically connected to the first bus bar; a plurality of second electrode fingers electrically connected to the second bus bar and arranged alternately with the plurality of first electrode fingers in a direction of propagation of an acoustic wave; a plurality of bar electrodes interposed between the first bus bar and the plurality of first electrode fingers, extending in parallel to the first bus bar and in parallel to each other; a plurality of connection portions including a connection portion interposed between the first bus bar and a bar electrode adjacent to the first bus bar to connect them, and a connection portion interposed between adjacent bar electrodes to connect them, at least some of the plurality of connection portions are discontinuously disposed with respect to an extension direction of the plurality of first electrode fingers, The shape of an opening region surrounded by the adjacent bar electrodes and the connection portions adjacent in the elastic wave propagation direction is an ellipse with the elastic wave propagation direction as a longitudinal direction, and a plurality of the opening regions having lengths in the longitudinal direction different from each other are arranged in the arrangement direction of the plurality of bar electrodes. Elastic wave device.

2. The plurality of connection portions are arranged in a direction inclined with respect to the extending direction. The acoustic wave device according to claim 1 .

3. the plurality of connection portions are arranged in a V-shape closing toward the plurality of first electrode fingers; The acoustic wave device according to claim 1 .

4. the plurality of connection portions are arranged in a Y shape opening toward the plurality of first electrode fingers; The acoustic wave device according to claim 1 .

5. In a plan view of the first surface, a region in which the IDT electrodes are located is a busbar region in which the first busbar is located; an intervening region in which the plurality of bar electrodes and the plurality of connecting portions are located; a gap region in which a gap is located adjacent to the tip of the second electrode fingers on the side of the intermediate region; the first electrode fingers and the second electrode fingers have an intersection region in which they overlap in the acoustic wave propagation direction; The intersection region is a central region located at a center of the intersection region in the extension direction and having a sound speed lower than that of the gap region; an edge region located between the central region and the gap region, the edge region having a sound velocity lower than that of the central region; The intervening region has a higher sound velocity than the busbar region. The acoustic wave device according to claim 1 .

6. the first electrode fingers are connected to a bar electrode located closest to the first electrode fingers, and the tip ends of the second electrode fingers face each other across a gap; and The acoustic wave device according to claim 1 .

7. a low acoustic velocity film that overlaps the piezoelectric body on the side opposite to the first surface and has a lower acoustic velocity than the piezoelectric body; The piezoelectric film further includes a high acoustic velocity film that overlaps the low acoustic velocity film on the opposite side to the piezoelectric film and has a higher acoustic velocity than the piezoelectric film. The acoustic wave device according to claim 1 .

8. The elastic wave device according to claim 1 , one or more other IDT electrodes located on the first surface and connected to the IDT electrodes in a ladder configuration to form a ladder filter; The filter has:

9. The elastic wave device according to claim 1 , one or more other IDT electrodes located on the first surface and arranged in the acoustic wave propagation direction relative to the IDT electrodes to configure a multimode filter; The filter has:

10. An antenna terminal; a transmission filter connected to the antenna terminal; a receiving filter connected to the antenna terminal; It has At least one of the transmission filter and the reception filter is constructed by the filter according to claim 8 or 9. Duplexer.

11. The duplexer according to claim 10; an antenna connected to the antenna terminal; an IC connected to the transmit filter and the receive filter; A communication device having the above configuration.

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