WO2018199071A1

WO2018199071A1 - Acoustic wave device manufacturing method and acoustic wave device

Info

Publication number: WO2018199071A1
Application number: PCT/JP2018/016563
Authority: WO
Inventors: 康晴中井; 晴信堀川
Original assignee: 株式会社村田製作所
Priority date: 2017-04-28
Filing date: 2018-04-24
Publication date: 2018-11-01
Also published as: JP6813084B2; JPWO2018199071A1

Abstract

Provided is an acoustic wave device manufacturing method with which a resist residue is less likely to remain and degradation in electric characteristics is less likely to occur, and which makes it possible to increase productivity. An acoustic wave device 1 manufacturing method is a method for manufacturing an acoustic wave device 1 having an IDT electrode 3 and is provided with: a step of preparing a piezoelectric substrate 2; a step of forming on the piezoelectric substrate 2 a first inner bus bar 4a, a plurality of first electrode fingers 4b, a second inner bus bar 5a, a plurality of second electrode fingers 5b, a plurality of first connection electrodes 4c, and a plurality of second connection electrodes 5c by a lift-off process; a step of forming a first bus bar 14 having a plurality of first opening portions 8 by forming a first outer bus bar 6 on the piezoelectric substrate 2 so as to cover a part of the plurality of first connection electrodes 4c; and a step of forming a second bus bar 15 having a plurality of second opening portions 9 by forming a second outer bus bar 7 on the piezoelectric substrate 2 so as to cover a part of the plurality of second connection electrodes 5c.

Description

Method for manufacturing elastic wave device and elastic wave device

The present invention relates to a method for manufacturing an elastic wave device and an elastic wave device.

Conventionally, in order to suppress unnecessary waves, an elastic wave device using a piston mode has been proposed.

For example, in Patent Document 1 below, an example of an acoustic wave device using a piston mode is shown. This elastic wave device is an elastic wave resonator having an IDT electrode. Here, the direction in which the electrode fingers of the IDT electrode extend is defined as the cross width direction. The IDT electrode has a central region arranged at the center in the cross width direction, a low sound velocity region arranged outside the cross width direction, and a high sound velocity region arranged further outside in the cross width direction.

The bus bar in the IDT electrode described in Patent Document 1 has a plurality of openings provided at the center in the cross width direction. The region provided with the plurality of openings is a high sound velocity region in the IDT electrode. A band-shaped inner bus bar portion located on the inner side in the cross width direction than the opening portion is a low sound velocity region. Thereby, the elastic wave device suppresses transverse mode ripple.

International Publication No. 2014/192755

When manufacturing an elastic wave device as described in Patent Document 1, it is necessary to form a fine electrode pattern having a plurality of openings in a bus bar. When such an electrode pattern is formed by the lift-off method, the resist is surrounded by the electrode in the opening portion. Therefore, when the resist is stripped, the stripping solution is not stable and hardly comes into contact with the resist, and a defect due to the resist residue may occur.

An object of the present invention is to provide a method of manufacturing an elastic wave device and an elastic wave device, in which resist residues are hardly generated, electrical characteristics are hardly deteriorated, and productivity can be improved. is there.

The method of manufacturing an acoustic wave device according to the present invention includes a first bus bar and a second bus bar facing each other, a plurality of first electrode fingers having one ends connected to the first bus bar, A method of manufacturing an acoustic wave device having an IDT electrode having one end connected to two bus bars and including a plurality of second electrode fingers that are interleaved with each other. A step of preparing a piezoelectric substrate; a first inner bus bar on the piezoelectric substrate; the plurality of first electrode fingers having one end connected to the first inner bus bar; and the first inner bus bar A second inner bus bar facing the bus bar, the plurality of second electrode fingers having one end connected to the second inner bus bar, and the plurality of first electrode fingers of the first inner bus bar. Connect one end to the opposite side of the connected side. A plurality of first connection electrodes, and a plurality of second connection electrodes having one ends connected to the side of the second inner busbar opposite to the side to which the plurality of second electrode fingers are connected And forming the first outer bus bar on the piezoelectric substrate so as to cover a part of the plurality of first connection electrodes, the first outer bus bar, Forming a first bus bar having a plurality of first openings surrounded by a plurality of first connection electrodes and the first inner bus bar; and part of the plurality of second connection electrodes. A second outer bus bar is formed on the piezoelectric substrate so as to cover the second outer bus bar, the plurality of second connection electrodes, and a plurality of second bus bars surrounded by the second inner bus bar. The second bus bar having an opening of And forming a.

In a specific aspect of the method for manufacturing an acoustic wave device according to the present invention, in the step of forming the first connection electrode, the first connection electrode on the first inner bus bar on the piezoelectric substrate. A third connection electrode connected to an end opposite to the connected side and extending in a direction intersecting with the direction in which the first connection electrode extends is formed. In this case, the electrical resistance of the IDT electrode can be lowered.

In another specific aspect of the method for manufacturing an acoustic wave device according to the present invention, in the step of forming the first connection electrode and the third connection electrode, a plurality of the third connection electrodes are spaced from each other. Form apart. In this case, the electrical resistance of the IDT electrode can be lowered, and the resist pattern can be easily peeled off effectively.

In still another specific aspect of the method for manufacturing an acoustic wave device according to the present invention, in the step of forming the first connection electrode and the third connection electrode, the third connection electrode, the plurality of first electrodes Forming a plurality of third openings surrounded by the connection electrode and the first inner bus bar, and the dimension along the direction in which the first connection electrode of the third opening extends is The third connection electrode is formed so as to be longer than a dimension along the direction in which the first connection electrode extends in the first opening. In this case, the electric resistance of the IDT electrode can be lowered and the resist pattern can be easily peeled off.

In another specific aspect of the method of manufacturing an acoustic wave device according to the present invention, the first connection electrode and the second connection electrode are in a direction in which the first electrode finger and the second electrode finger extend. It extends in the parallel direction.

In still another specific aspect of the method for manufacturing an acoustic wave device according to the present invention, the first connection electrode and the second connection electrode extend in the direction in which the first electrode finger and the second electrode finger extend. It extends in the direction of crossing. In this case, spurious due to the transverse mode can be suppressed.

In still another specific aspect of the method for manufacturing an elastic wave device according to the present invention, the elastic wave propagation direction is the first direction, and the direction in which the first electrode finger and the second electrode finger extend is the second direction. When the direction is set, the IDT electrode has a crossing region in which the first electrode finger and the second electrode finger overlap in the first direction. A central region located on the center side in the second direction, and a first edge region and a second edge region disposed on both sides of the central region in the second direction, and the first region An edge region is located on the first inner busbar side, the second edge region is located on the second inner busbar side, and the first edge region and the second edge region The sound speed is lower than the sound speed in the central region. In this case, spurious due to the transverse mode can be suppressed.

In still another specific aspect of the method for manufacturing an acoustic wave device according to the present invention, the method further includes a step of forming a wiring electrode on the piezoelectric substrate so as to be connected to the first outer bus bar. The step of forming the wiring electrode is performed simultaneously with the step of forming the first outer bus bar. In this case, productivity can be further enhanced.

In still another specific aspect of the method for manufacturing an acoustic wave device according to the present invention, the method further includes a step of forming a terminal on the piezoelectric substrate so as to be connected to the wiring electrode, and the terminal is formed. The step is performed simultaneously with the step of forming the first outer bus bar and the wiring electrode. In this case, productivity can be further enhanced.

An elastic wave device according to the present invention includes a piezoelectric substrate and an IDT electrode provided on the piezoelectric substrate, and the IDT electrode has one end connected to a first inner bus bar and the first inner bus bar. A plurality of first electrode fingers, a second inner bus bar facing the first inner bus bar, and one end connected to the second inner bus bar, and the plurality of first electrodes A plurality of second electrode fingers that are interdigitated with the fingers and a plurality of ends connected to the side of the first inner busbar opposite to the side to which the plurality of first electrode fingers are connected A plurality of second connection electrodes whose one ends are connected to a side opposite to a side to which the plurality of second electrode fingers of the second inner bus bar are connected; Provided on the plurality of first connection electrodes and on the piezoelectric substrate; A first outer bus bar; a first outer bus bar; a plurality of first connection electrodes; a plurality of first openings surrounded by the first inner bus bar; and the plurality of second connection electrodes. A second outer bus bar provided on the piezoelectric substrate and the second outer bus bar, a plurality of second openings surrounded by the second outer bus bar, the plurality of second connection electrodes, and the second inner bus bar Part.

In a specific aspect of the acoustic wave device according to the present invention, the plurality of first connection electrodes and the second connection electrodes intersect with a direction in which the first electrode fingers and the second electrode fingers extend. Extending in the direction. In this case, spurious due to the transverse mode can be suppressed.

In another specific aspect of the elastic wave device according to the present invention, the elastic wave propagation direction is the first direction, and the direction in which the first electrode finger and the second electrode finger extend is the second direction. In addition, the IDT electrode has a crossing region in which the first electrode finger and the second electrode finger overlap in the first direction, and the IDT electrode is in the crossing region, A central region located on the center side in the second direction, and a first edge region and a second edge region disposed on both sides of the central region in the second direction, and the first region The edge region is located on the first inner busbar side, the second edge region is located on the second inner busbar side, and the first edge region and the second edge region Is faster than the sound speed in the central region. There. In this case, spurious due to the transverse mode can be suppressed.

In still another specific aspect of the acoustic wave device according to the present invention, the first outer bus bar is provided on an uneven portion including the plurality of first connection electrodes and the piezoelectric substrate, and the second The outer bus bar is provided on the concavo-convex portion composed of the plurality of second connection electrodes and the piezoelectric substrate. In this case, the joining force between the first outer bus bar and the plurality of first connection electrodes can be increased. Similarly, the bonding force between the second outer bus bar and the plurality of second connection electrodes can be increased.

According to the present invention, it is possible to provide a method of manufacturing an elastic wave device and an elastic wave device that are unlikely to cause resist residue, can hardly cause deterioration of electrical characteristics, and can improve productivity. it can.

FIG. 1 is a plan view of an acoustic wave device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line II in FIG. FIG. 3 is an enlarged plan view near the first edge region of the IDT electrode in the first embodiment of the present invention. FIG. 4 is an enlarged front cross-sectional view of the first electrode finger in the first embodiment of the present invention. FIG. 5A and FIG. 5B are plan views for explaining an example of the method for manufacturing the acoustic wave device according to the first embodiment of the present invention. FIG. 6A and FIG. 6B are plan views for explaining an example of the method for manufacturing the acoustic wave device according to the first embodiment of the present invention. FIG. 7 is a front cross-sectional view for explaining an example of the method for manufacturing the acoustic wave device according to the first embodiment of the present invention. FIG. 8 is a diagram showing the relationship between the return loss at the intermediate frequency between the resonance frequency and the antiresonance frequency and the first opening length of the acoustic wave device according to the first embodiment of the present invention. FIG. 9 is a plan view of an IDT electrode in the first modification of the first embodiment of the present invention. FIG. 10 is a plan view of an IDT electrode in a second modification of the first embodiment of the present invention. FIG. 11 is a plan view of an IDT electrode according to a third modification of the first embodiment of the present invention. FIG. 12 is a plan view of an IDT electrode according to the second embodiment of the present invention. FIG. 13 is a plan view of an IDT electrode in a first modification of the second embodiment of the present invention. FIG. 14 is a plan view of an IDT electrode in a second modification of the second embodiment of the present invention. FIG. 15 is a plan view of an IDT electrode according to the third embodiment of the present invention. FIG. 16 is a plan view of an acoustic wave device according to the fourth embodiment of the present invention. FIG. 17 is a plan view of an acoustic wave device according to the fifth embodiment of the present invention.

Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

It should be pointed out that each embodiment described in this specification is an example, and a partial replacement or combination of configurations is possible between different embodiments.

FIG. 1 is a plan view of an acoustic wave device according to a first embodiment of the present invention. In FIG. 1, a first dielectric film and a second dielectric film, which will be described later, are omitted.

The acoustic wave device 1 has a piezoelectric substrate 2. In the present embodiment, the piezoelectric substrate 2 is made of 127.5 ° YX LiNbO ₃ . The cut angle of the piezoelectric substrate 2 is not limited to the above. The piezoelectric substrate 2, such as LiTaO _3, may be made of a piezoelectric single crystal other than _{LiNbO 3,} or may be made from a suitable piezoelectric ceramic.

An IDT electrode 3 is provided on the piezoelectric substrate 2. When an AC voltage is applied to the IDT electrode 3, an elastic wave is excited. A reflector 13a and a reflector 13b are provided on both sides of the IDT electrode 3 in the elastic wave propagation direction. Thus, in this embodiment, the elastic wave device 1 is a 1-port type elastic wave resonator. The elastic wave device of the present invention is not limited to this, and may be, for example, a ladder type filter having a plurality of elastic wave resonators or a longitudinally coupled resonator type elastic wave filter having a plurality of IDT electrodes.

The elastic wave device 1 of the present embodiment uses a piston mode, and the IDT electrode 3 includes a first low sound velocity region La, a first high sound velocity region Ha, a second low sound velocity region Lb, and a second sound wave, which will be described later. High sound velocity region Hb. This will be described more specifically below.

The IDT electrode 3 has a first inner bus bar 4a and a second inner bus bar 5a facing each other. The IDT electrode 3 has a plurality of first electrode fingers 4b, one end of which is connected to the first inner bus bar 4a. Furthermore, the IDT electrode 3 has a plurality of second electrode fingers 5b, one end of which is connected to the second inner bus bar 5a. The plurality of first electrode fingers 4b and the plurality of second electrode fingers 5b are interleaved with each other.

Here, the elastic wave propagation direction is defined as a first direction x, and the direction in which the first electrode finger 4b and the second electrode finger 5b extend is defined as a second direction y. In the present embodiment, the direction orthogonal to the first direction x and the second direction y are parallel.

The IDT electrode 3 has a plurality of first connection electrodes 4c whose one ends are connected to the side opposite to the side where the first electrode fingers 4b of the first inner bus bar 4a are connected. In the present embodiment, the first connection electrode 4c extends in parallel to the second direction y. The first inner bus bar 4a and the plurality of first connection electrodes 4c form a comb-like electrode pattern, and a gap is formed between the electrodes on the outer side in the second direction y.

The IDT electrode 3 has a plurality of second connection electrodes 5c whose one ends are connected to the side opposite to the side where the second electrode fingers 5b of the second inner bus bar 5a are connected. In the present embodiment, the second connection electrode 5c extends in parallel with the second direction y. The second inner bus bar 5a and the plurality of second connection electrodes 5c form a comb-like electrode pattern, and a gap is formed between the electrodes on the outer side in the second direction y.

A first outer bus bar 6 is provided on the piezoelectric substrate 2 so as to cover a part of the plurality of first connection electrodes 4c. The first outer bus bar 6, the plurality of first connection electrodes 4c, and the first inner bus bar 4a constitute a first bus bar. The first bus bar 14 has a plurality of first openings 8 surrounded by the first outer bus bar 6, the plurality of first connection electrodes 4c, and the first inner bus bar 4a.

FIG. 2 is a cross-sectional view taken along the line II in FIG. In FIG. 2, a first dielectric film and a second dielectric film described later are omitted.

The first outer bus bar 6 is provided on an uneven portion formed by the piezoelectric substrate 2 and the plurality of first connection electrodes 4c.

Returning to FIG. 1, a second outer bus bar 7 is provided on the piezoelectric substrate 2 so as to cover a part of the plurality of second connection electrodes 5c. The second outer bus bar 7 is provided on the uneven portion formed by the piezoelectric substrate 2 and the plurality of second connection electrodes 5c. The second outer bus bar 7, the plurality of second connection electrodes 5c, and the second inner bus bar 5a constitute a second bus bar 15. The second bus bar 15 has a plurality of second openings 9 surrounded by the second outer bus bar 7, the plurality of second connection electrodes 5c, and the second inner bus bar 5a.

The IDT electrode 3 has a crossing region A, which is a portion where the first electrode finger 4b and the second electrode finger 5b overlap in the first direction x. The crossing region A has a central region B located at the center of the first electrode finger 4b and the second electrode finger 5b in the second direction y. The crossing region A has a first edge region Ca and a second edge region Cb arranged outside the central region B in the second direction y. The first edge region Ca is located on the first inner bus bar 4a side, and the second edge region Cb is located on the second inner bus bar 5a side.

FIG. 3 is an enlarged plan view near the first edge region of the IDT electrode according to the first embodiment.

The dimension along the first direction x of the first electrode finger 4b and the second electrode finger 5b is defined as the width. The first electrode finger 4b has a wide portion 16 that is wider than other portions in the first edge region Ca. The second electrode finger 5b also has a wide portion 17 that is wider than other portions in the first edge region Ca. Thereby, the sound speed in the first edge area Ca is lower than the sound speed in the central area B. Furthermore, the sound speed in the area where the first inner bus bar 4a is provided is also lower than the sound speed in the central area B. Thus, the first low sound velocity region La in which the average sound velocity is lower than the sound velocity in the central region B is configured from the first edge region Ca to the region where the first inner bus bar 4a is provided. In the present specification, the speed of sound is the propagation speed of the elastic wave in the first direction x.

Referring back to FIG. 1, the first electrode finger 4b and the second electrode finger 5b have a wide portion also in the second edge region Cb. From the second edge region Cb to the region where the second inner bus bar 5a is provided, a second low sound velocity region Lb in which the average sound velocity is lower than the sound velocity in the central region B is configured.

The first opening 8 is located outside the first edge region Ca in the second direction y. In the present embodiment, the first connection electrode 4c constituting the first opening 8 is located on the extension line of the first electrode finger 4b in the second direction y, and the second electrode It is not located on the extension line of the finger 5b. Therefore, the occupation ratio of the electrodes along the first direction x in the region where the first opening 8 is provided is smaller than the occupation ratio of the electrodes along the first direction x in the central region B. Therefore, in the region where the first opening 8 is provided, the first high sound velocity region Ha is configured in which the sound velocity is higher than the sound velocity in the central region B.

The second opening 9 is located outside the second edge region Cb in the second direction y. Similar to the region in which the first opening 8 is provided, the second high sound velocity region Hb having a higher sound speed than the sound velocity in the central region B is configured in the region in which the second opening 9 is provided. Has been.

Thus, the central region B, the first low sound velocity region La, and the first high sound velocity region Ha are arranged in this order, and the central region B, the second low sound velocity region Lb, and the second high sound velocity region Ha. Hb is arranged in this order. As a result, the energy of the elastic wave is confined and spurious due to higher-order transverse modes is suppressed.

FIG. 4 is an enlarged front cross-sectional view of the first electrode finger in the first embodiment.

In the present embodiment, the first electrode finger 4b is connected to the first metal layer 3a, the second metal layer 3b, the third metal layer 3c, the fourth metal layer 3d, and the fifth metal layer from the piezoelectric substrate 2 side. The metal layer 3e is composed of a laminated metal film laminated in this order. The first metal layer 3a is made of NiCr. The second metal layer 3b is made of Pt. The third metal layer 3c is made of Ti. The fourth metal layer 3d is made of AlCu. The fifth metal layer 3e is made of Ti. The film thickness of the first metal layer 3a is 10 nm, the film thickness of the second metal layer 3b is 72 nm, the film thickness of the third metal layer 3c is 60 nm, and the film of the fourth metal layer 3d. The thickness is 130 nm, and the thickness of the fifth metal layer 3e is 10 nm. The other first electrode fingers, the plurality of second electrode fingers, the plurality of first connection electrodes, and the plurality of second connection electrodes of the IDT electrode are similarly configured.

Note that the materials and film thicknesses of the plurality of first electrode fingers, the plurality of second electrode fingers, the plurality of first connection electrodes, and the plurality of second connection electrodes are not limited to the above. The plurality of first electrode fingers, the plurality of second electrode fingers, the plurality of first connection electrodes, and the plurality of second connection electrodes may be formed of a single layer metal film. The first outer bus bar and the second outer bus bar may also be made of a laminated metal film in which a plurality of metal layers are laminated, or may be made of a single-layer metal film.

A first dielectric film 18 is provided on the piezoelectric substrate 2 so as to cover the IDT electrode and the reflector. Although the first dielectric film 18 is not particularly limited, it is made of SiO ₂ . Thereby, the frequency temperature characteristic can be improved. The film thickness of the first dielectric film 18 is not particularly limited, but is 1110 nm.

A second dielectric film 19 is provided on the first dielectric film 18. Although the second dielectric film 19 is not particularly limited, it is made of SiN. By adjusting the film thickness of the second dielectric film 19, the frequency can be easily adjusted. The film thickness of the second dielectric film 19 is not particularly limited, but is 40 nm. Note that the first dielectric film 18 and the second dielectric film 19 may not be provided.

Returning to FIG. 1, the feature of this embodiment is that the first outer bus bar 6 is provided on the piezoelectric substrate 2 so as to cover a part of the plurality of first connection electrodes 4c, and the plurality of second connection electrodes 4c are provided. The second outer bus bar 7 is provided on the piezoelectric substrate 2 so as to cover a part of the connection electrode 5c. Thereby, when manufacturing the acoustic wave device 1, it is possible to make it difficult to generate a resist residue. Accordingly, it is possible to make it difficult for electrical characteristics such as filter characteristics to deteriorate, and to increase productivity. This will be described below together with an example of a method for manufacturing the acoustic wave device 1 of the present embodiment.

FIG. 5A and FIG. 5B are plan views for explaining an example of the method for manufacturing the acoustic wave device according to the first embodiment. FIG. 6A and FIG. 6B are plan views for explaining an example of the method for manufacturing the acoustic wave device according to the first embodiment. FIG. 7 is a front cross-sectional view for explaining an example of the method for manufacturing the acoustic wave device according to the first embodiment. In FIG. 5A, a resist pattern described later is indicated by hatching.

As shown in FIG. 5A, a piezoelectric substrate 2 is prepared. Next, the IDT electrode first inner bus bar, the plurality of first electrode fingers, the second inner bus bar, the plurality of second electrode fingers, the plurality of second electrode fingers, and the like on the piezoelectric substrate 2 by a lift-off method. A first connection electrode and a plurality of second connection electrodes are formed.

More specifically, a resist layer is formed on the piezoelectric substrate 2. The resist layer can be formed by, for example, a printing method or a spin coating method. Next, the resist pattern 22 is formed by developing after exposing the resist layer. The portions corresponding to the IDT electrodes in the resist pattern 22 are all continuous.

Next, as shown in FIG. 5B, on the piezoelectric substrate 2 so as to cover the resist pattern 22, a first inner bus bar, a second inner bus bar, a first electrode finger, a second electrode finger, A metal film 23 for the first connection electrode and the second connection electrode is formed. The metal film 23 is formed by a vacuum deposition method. The metal film 23 may be formed by an appropriate method such as sputtering.

Next, the resist pattern 22 is peeled off. At this time, as described above, since the portions corresponding to the IDT electrodes of the resist pattern 22 are all continuous, the resist pattern 22 can be easily and more reliably peeled off. Accordingly, as shown in FIG. 6A, the first inner bus bar 4a, the second inner bus bar 5a, the plurality of first electrode fingers 4b, the plurality of second electrode fingers 5b, and the plurality of first electrodes. A connection electrode 4c and a plurality of second connection electrodes 5c can be formed.

Next, as shown in FIG. 6B, the first outer bus bar 6 is formed on the piezoelectric substrate 2 so as to cover a part of the plurality of first connection electrodes 4c. As a result, the first bus bar 14 having the plurality of first openings 8 surrounded by the first outer bus bar 6, the plurality of first connection electrodes 4c and the first inner bus bar 4a is formed. At the same time, the second outer bus bar 7 is formed on the piezoelectric substrate 2 so as to cover a part of the plurality of second connection electrodes 5c. As a result, a second bus bar 15 having a plurality of second openings 9 surrounded by the second outer bus bar 7, the plurality of second connection electrodes 5c, and the second inner bus bar 5a is formed. The first outer bus bar 6 and the second outer bus bar 7 can be formed by a lift-off method. Thereby, the IDT electrode 3 can be formed on the piezoelectric substrate 2.

In addition, the reflector 13a and the reflector 13b are also formed by the lift-off method simultaneously with the IDT electrode 3.

Next, as shown in FIG. 7, a first dielectric film 18 is formed on the piezoelectric substrate 2 so as to cover the IDT electrode 3, the reflector 13a, and the reflector 13b. Next, a second dielectric film 19 is formed on the first dielectric film 18. The first dielectric film 18 and the second dielectric film 19 can be formed by, for example, a sputtering method or a vacuum evaporation method.

In the manufacture of the elastic wave device 1 of the present embodiment, the first bus bar and the second bus bar are formed by the steps shown in FIGS. 5 (a), 5 (b) and 6 (a) and FIG. 6 (b). ) And the process shown in FIG. Therefore, as shown in FIG. 5A, in the portions corresponding to the first opening and the second opening of the IDT electrode, the resist layer is not surrounded by the portion from which the resist layer has been removed. Thereby, as shown in FIG. 5B, the resist layer in the portion corresponding to the IDT electrode of the resist pattern 22 is not surrounded by the portion where the metal film 23 is directly formed on the piezoelectric substrate 2. . For this reason, all the portions corresponding to the IDT electrodes of the resist pattern 22 can be connected. Therefore, the resist pattern 22 can be easily peeled off, and the production efficiency can be increased. In addition, since the resist pattern 22 can be peeled off more reliably, the occurrence rate of defects due to resist residues can be reduced. Therefore, productivity can be improved effectively.

Here, the wavelength defined by the electrode finger pitch of the IDT electrode 3 shown in FIG. A dimension along the second direction y of the first opening 8 is defined as a first opening length. A dimension along the second direction y of the second opening 9 is defined as a second opening length. In the present embodiment, the first opening length is the distance between the first inner bus bar 4a and the first outer bus bar 6, and the second opening length is the second inner bus bar 5a and the second outer bus bar. 7 distance. The first opening length and the second opening length are preferably 2λ or less. Thereby, the electrical resistance of the IDT electrode 3 can be lowered.

On the other hand, the first opening length and the second opening length are preferably 1λ or more, and more preferably 1.2λ or more. Thereby, the return loss can be improved. This will be described below.

The return loss at the intermediate frequency between the resonance frequency and the antiresonance frequency of the elastic wave device 1 of the present embodiment was evaluated under the following conditions. The dimension along the second direction y of the first bus bar 14 and the second bus bar 15 is the width of the first inner bus bar 4a and the second inner bus bar 5a. On the other hand, in the present embodiment, the dimension of the first electrode finger 4b and the second electrode finger 5b along the second direction y is the length of the first electrode finger 4b and the second electrode finger 5b. As described above, the dimension along the first direction x of the first electrode finger 4b and the second electrode finger 5b is the width of the first electrode finger 4b and the second electrode finger 5b. A dimension along the second direction y of the crossing area A is defined as a crossing width.

Piezoelectric substrate: Material 127.5 ° YX LiNbO ₃
Width of the first inner bus bar and the second inner bus bar: 0.85 μm
Width of first electrode finger and second electrode finger (other than wide part): 1 μm
The width of the wide part of the first electrode finger and the wide part of the second electrode finger: 1.4 μm
Length of the wide part of the first electrode finger and the wide part of the second electrode finger: 1 μm
Wavelength: 4μm
Cross width: 40 μm
Number of pairs of first electrode fingers and second electrode fingers: 150 pairs

FIG. 8 is a diagram showing the relationship between the return loss at the intermediate frequency between the resonance frequency and the anti-resonance frequency and the first opening length of the elastic wave device according to the first embodiment.

As shown in FIG. 8, when the first opening length is in the range of 1λ or more and 2λ or less, the absolute value of the return loss can be 0.35 or less, and the return loss can be improved. It can be seen that when the first opening length is in the range from 1.2λ to 2λ, the return loss can be further improved.

By the way, as shown in FIG. 2, the first outer bus bar 6 is provided on the concavo-convex portion including the plurality of first connection electrodes 4 c and the piezoelectric substrate 2. Thereby, the bonding force between the first outer bus bar 6 and the plurality of first connection electrodes 4c can be increased. Similarly, the bonding force between the second outer bus bar and the plurality of second connection electrodes can be increased. Therefore, the IDT electrode is hardly damaged, and the reliability of the acoustic wave device 1 can be improved.

As shown in FIG. 3, in the present embodiment, in the first edge region Ca, the first electrode finger 4 b has the wide portion 16 and the second electrode finger 5 b has the wide portion 17. The sound speed is low. In addition, the structure which makes the sound speed of 1st edge area | region Ca low is not limited to this. For example, in the first edge region Ca, a mass addition film may be provided on the first electrode finger 4b and the second electrode finger 5b. The same applies to the configuration for lowering the sound speed in the second edge region.

Hereinafter, first to third modifications of the first embodiment will be described. In the first to third modifications, the configurations of the first bus bar and the second bus bar are different from those of the first embodiment. Except for the above points, the first to third modifications are configured in the same manner as in the first embodiment. In the first to third modifications, the first inner bus bar and the first outer bus bar in the first bus bar and the second inner bus bar and the second outer bus bar in the second bus bar are the first bus bar, It is comprised similarly to embodiment of this. Also in the first to third modifications, the productivity can be improved as in the first embodiment.

FIG. 9 is a plan view of the IDT electrode in the first modification of the first embodiment. FIG. 9 shows the vicinity of a portion where the IDT electrode is provided on the piezoelectric substrate. The same applies to each drawing showing IDT electrodes, which will be described later.

In the present modification, the first connection electrode 4c is provided on an extension line in the second direction y of the second electrode finger 5b. The second connection electrode 5c is provided on an extension line in the second direction y of the first electrode finger 4b.

FIG. 10 is a plan view of the IDT electrode in the second modification of the first embodiment.

In the present modification, the width of the first connection electrode 104c is wider than the width of the first electrode finger 4b. Each first connection electrode 104c is provided to face every other first electrode finger 4b via the first inner bus bar 4a. Similarly, the width of the second connection electrode 105c is wider than the width of the first electrode finger 4b. Each second connection electrode 105c is provided on an extension line in the second direction y of every other one or more first electrode fingers 4b.

FIG. 11 is a plan view of an IDT electrode according to a third modification of the first embodiment.

In the present modification, the first connection electrode 114c and the second connection electrode 115c have a curved shape. The first opening 118 and the second opening 119 also have a curved shape.

FIG. 12 is a plan view of the IDT electrode in the second embodiment.

In the present embodiment, the IDT electrode 33 includes a third connection electrode 34c connected to the first connection electrode 4c and a fourth connection electrode 35c connected to the second connection electrode 5c. Except for the above points, the elastic wave device of the present embodiment has the same configuration as the elastic wave device 1 of the first embodiment.

The third connection electrode 34c is connected to the end of the plurality of first connection electrodes 4c opposite to the side connected to the first inner bus bar 4a. The third connection electrode 34c is provided so that a plurality of third openings 38 surrounded by the third connection electrode 34c, the plurality of first connection electrodes 4c, and the first inner bus bar 4a are formed. ing. On the other hand, also on the second bus bar 35 side, a plurality of fourth connection electrodes 35c are provided so that a plurality of fourth openings 39 are formed, similarly to the first bus bar 34 side. By having the third connection electrode 34c and the fourth connection electrode 35c, the electrical resistance of the IDT electrode 33 can be reduced.

The third connection electrode 34c extends in the first direction x. The third connection electrode 34c only needs to extend in a direction crossing the direction in which the first connection electrode 4c extends. The same applies to the fourth connection electrode 35c.

Here, as shown in FIG. 12, the first opening length is D1, and the second opening length is D2. The dimension along the second direction y of the third opening 38 is defined as a third opening length D3, and the dimension along the second direction y of the fourth opening 39 is defined as a fourth opening length D4. At this time, the third opening length D3 is longer than the first opening length D1. Similarly, the fourth opening length D4 is longer than the second opening length D2.

In manufacturing the acoustic wave device according to the second embodiment, the third connection electrode 34c and the fourth connection electrode 4c are formed on the piezoelectric substrate 2 in the step of forming the first connection electrode 4c and the second connection electrode 5c. The connection electrode 35c may be formed. At this time, the first connection electrode 4c is connected to the end opposite to the side connected to the first inner bus bar 4a, and the plurality of third openings 38 are formed. 3 connection electrodes 34c may be formed. Similarly, the second connection electrode 5c is connected to the end opposite to the side connected to the second inner bus bar 5a, and the plurality of fourth openings 39 are formed. Four connection electrodes 35c may be formed.

At this time, on the first bus bar 34 side, since the third opening length D3 is longer than the first opening length D1, the resist pattern can be easily peeled off, and defects due to the resist residue hardly occur. . The same applies to the second bus bar 35 side. Therefore, productivity can also be improved in this embodiment.

However, as in the first embodiment shown in FIG. 1, it is preferable that a gap is formed between the electrodes outside the first inner bus bar 4a in the second direction y and the electrodes are not connected. . It is preferable that a gap is formed between the electrodes outside the second inner bus bar 5a in the second direction y, and the electrodes are not connected. Thereby, the resist pattern can be more easily and more reliably peeled off.

In addition, the process after the process of forming the 1st connection electrode 4c and the 2nd connection electrode 5c is the same as that of the manufacturing method of the elastic wave apparatus 1 of 1st Embodiment.

FIG. 13 is a plan view of the IDT electrode in the first modification of the second embodiment.

In this modification, the second embodiment is different in that a plurality of third connection electrodes 124c are provided with a gap therebetween and a plurality of fourth connection electrodes 125c are provided with a gap therebetween. And different. Except for the above points, the elastic wave device of the present modification has the same configuration as the elastic wave device of the second embodiment.

In the present modification, as in the first embodiment, a gap is formed between the electrodes outside the first inner bus bar 4a in the second direction y, and the electrodes are not connected. A gap is formed between the electrodes on the outer side in the second direction y than the second inner bus bar 5a, and the electrodes are not connected. Therefore, the productivity can be effectively increased as in the first embodiment.

In manufacturing the acoustic wave device according to this modification, in the step of forming the first connection electrode 4c and the third connection electrode 124c, the plurality of third connection electrodes 124c are formed with a gap therebetween. do it. Other processes are the same as the processes in manufacturing the acoustic wave device of the second embodiment.

FIG. 14 is a plan view of an IDT electrode according to a second modification of the second embodiment.

This modification is the first modification of the second embodiment in that the first bus bar 134 includes a plurality of first electrodes 134c and the second bus bar 135 includes a plurality of second electrodes 135c. Different from the example. Except for the above points, the elastic wave device of the present modification has the same configuration as the elastic wave device of the first modification of the second embodiment.

The first electrode 134c is provided on an extension line of the first electrode finger 4b in the second direction y. The first electrode 134c extends in parallel with the direction in which the first connection electrode 4c extends. A gap is formed between the end portion of the first electrode 134c on the first inner bus bar 4a side and the first inner bus bar 4a. The first connection electrodes 4c and the plurality of first electrodes 134c are alternately arranged along the first direction x.

A third connection electrode 124c is connected to the end of the first electrode 134c opposite to the first inner bus bar 4a side. A gap is formed between the third connection electrode 124c connected to the first electrode 134c and the third connection electrode 124c connected to the first connection electrode 4c. On the other hand, the second bus bar 135 side is configured similarly to the first bus bar 134 side.

Also in this modification, a gap is formed between the third connection electrodes 124c and between the fourth connection electrodes 125c, as in the first modification of the second embodiment. In addition, gaps are also formed between the first electrode 134c and the first inner bus bar 4a and between the second electrode 135c and the second inner bus bar 5a. Therefore, also in this modified example, in the manufacturing process, the resist pattern can be easily and more reliably peeled off, and productivity can be improved.

FIG. 15 is a plan view of an IDT electrode according to the third embodiment.

The third embodiment is different in that the first connection electrode 44c and the second connection electrode 45c extend in a direction intersecting with the direction in which the first electrode finger 44b and the second electrode finger 45b extend. Different from the first embodiment. Furthermore, the third embodiment is different from the first embodiment in that the first electrode finger 44b and the second electrode finger 45b do not have a wide portion. Except for the above points, the elastic wave device of the third embodiment has the same configuration as the elastic wave device 1 of the first embodiment.

Also in the present embodiment, the productivity can be effectively increased as in the first embodiment.

In the present embodiment, since the plurality of first connection electrodes 44c extend in a direction crossing the second direction y, the first opening 48 is inclined with respect to the second direction y. Similarly, the second opening 49 is also inclined with respect to the second direction y.

Here, the transverse mode generated when the elastic wave is excited in the crossing region propagates to the first bus bar 44 side and the second bus bar 45 side. Since the first bus bar 44 and the second bus bar 45 have the first opening 48 and the second opening 49 inclined as described above, the transverse mode can be reflected to the crossing region side. The reflected transverse mode and the transverse mode propagating from the crossing region to the first bus bar 44 side and the second bus bar 45 side are canceled out. Thereby, spurious due to the transverse mode can be suppressed.

In the present embodiment also, the first electrode finger 44b and the second electrode finger 45b may have wide portions in the first edge region and the second edge region.

FIG. 16 is a plan view of the acoustic wave device according to the fourth embodiment. In addition, the dashed-dotted line in FIG. 16 shows the boundary line of each IDT electrode and each wiring electrode mentioned later, and the boundary line between each wiring electrode and each terminal mentioned later.

The elastic wave device 51 of the present embodiment includes a longitudinally coupled resonator type acoustic wave filter 52, a wiring electrode 58 connected to the longitudinally coupled resonator type acoustic wave filter 52, and a plurality of wiring electrodes 58 connected to the wiring electrode 58. Terminal. The wiring electrode 58 and the plurality of terminals are provided on the piezoelectric substrate 2.

The longitudinally coupled resonator type acoustic wave filter 52 includes a first IDT electrode 53A, a second IDT electrode 53B, and a third IDT electrode 53C arranged along the first direction x. The first IDT electrode 53A, the second IDT electrode 53B, and the third IDT electrode 53C have the same configuration as the IDT electrode in the first embodiment. A reflector 13a is disposed on the opposite side of the first IDT electrode 53A to the second IDT electrode 53B side, and a reflector 13b is provided on the opposite side of the third IDT electrode 53C to the second IDT electrode 53B side. Is arranged. In the present embodiment, the longitudinally coupled resonator type acoustic wave filter 52 has three IDT electrodes, but the number of IDT electrodes is not limited to the above.

In the present embodiment, the plurality of terminals are an input terminal 59a, an output terminal 59b, and a ground terminal 59c. An output terminal 59b is connected to the first outer bus bar 56A of the first IDT electrode 53A via a wiring electrode 58. A ground terminal 59c is connected to the second outer bus bar 57A of the first IDT electrode 53A via a wiring electrode 58. A ground terminal 59c is connected to the first outer bus bar 56B of the second IDT electrode 53B via a wiring electrode 58. An input terminal 59a is connected to the second outer bus bar 57B of the second IDT electrode 53B via a wiring electrode 58. An output terminal 59b is connected to the first outer bus bar 56C of the third IDT electrode 53C via a wiring electrode 58. A ground terminal 59c is connected to the second outer bus bar 57C of the third IDT electrode 53C via a wiring electrode 58.

Since the first IDT electrode 53A, the second IDT electrode 53B, and the third IDT electrode 53C have the same configuration as the IDT electrode in the first embodiment, the resist pattern can be easily and more easily formed in the manufacturing process. It can be reliably peeled off. Therefore, the productivity can be increased as in the first embodiment.

When manufacturing the acoustic wave device 51 of the present embodiment, as in the method of manufacturing the acoustic wave device 1 of the first embodiment, the first inner bus bar, the second inner bus bar, the plurality of first electrode fingers, A plurality of second electrode fingers, a plurality of first connection electrodes, and a plurality of second connection electrodes are formed. It is preferable to simultaneously form the above-described portions of the first IDT electrode 53A, the second IDT electrode 53B, and the third IDT electrode 53C. Thereby, productivity can be improved.

Next, the first outer bus bar 56A is formed in the same manner as in the method of manufacturing the acoustic wave device 1 of the first embodiment. At this time, it is preferable to form the wiring electrode 58 on the piezoelectric substrate 2 so as to be connected to the first outer bus bar 56A simultaneously with the first outer bus bar 56A. More preferably, the output terminal 59b is formed on the piezoelectric substrate 2 so as to be connected to the wiring electrode 58 simultaneously with the first outer bus bar 56A and the wiring electrode 58. Here, the first outer bus bar 56B, the first outer bus bar 56C, the second outer bus bar 57A, the second outer bus bar 57B, the second outer bus bar 57C, the other wiring electrodes 58, the other output terminals 59b, More preferably, the input terminal 59a and each ground terminal 59c are formed simultaneously. Thereby, productivity can be further increased.

The subsequent steps are the same as the manufacturing method of the acoustic wave device 1 of the first embodiment.

FIG. 17 is a plan view of the acoustic wave device according to the fifth embodiment.

The elastic wave device 61 of the present embodiment is a ladder type filter having a plurality of elastic wave resonators. The acoustic wave device 61 includes a wiring electrode 68 that electrically connects a plurality of acoustic wave resonators, and a plurality of terminals that are electrically connected to the plurality of acoustic wave resonators via a wiring electrode 58. Have. The wiring electrode 58, the wiring electrode 68, and the plurality of terminals are provided on the piezoelectric substrate.

The plurality of elastic wave resonators in the elastic wave device 61 are a first elastic wave resonator 62A, a second elastic wave resonator 62B, and a third elastic wave resonator 62C. The first elastic wave resonator 62A, the second elastic wave resonator 62B, and the third elastic wave resonator 62C have the same configuration as that of the elastic wave device 1 of the first embodiment. In addition, although the elastic wave apparatus 61 of this embodiment has three elastic wave resonators, the number of elastic wave resonators is not specifically limited.

In the present embodiment, the plurality of terminals are an input terminal 59a, an output terminal 59b, and a ground terminal 59c. An input terminal 59a is connected to the first outer bus bar of the first acoustic wave resonator 62A via a wiring electrode 58. A ground terminal 59c is connected to the first outer bus bar of the second acoustic wave resonator 62B through a wiring electrode 58. An output terminal 59b is connected to the second outer bus bar of the third elastic wave resonator 62C through a wiring electrode 58. The second outer bus bar of the first elastic wave resonator 62A, the second outer bus bar of the second elastic wave resonator 62B, and the first outer bus bar of the third elastic wave resonator 62C are formed by wiring electrodes 68. It is connected. The first elastic wave resonator 62A and the third elastic wave resonator 62C are series arm resonators in a ladder type filter, and the second elastic wave resonator 62B is a parallel arm resonator.

The first elastic wave resonator 62A, the second elastic wave resonator 62B, and the third elastic wave resonator 62C have the same configuration as that of the first embodiment. Therefore, the productivity can be increased as in the first embodiment.

When manufacturing the elastic wave device 61, the steps of configuring the first elastic wave resonator 62A, the second elastic wave resonator 62B, and the third elastic wave resonator 62C are performed in the same manner as in the first embodiment. Can do. As in the fourth embodiment, each first outer bus bar, each second outer bus bar, each wiring electrode 58, wiring electrode 68, input terminal 59a, output terminal 59b, and ground terminal 59c are formed simultaneously. Is preferred. Thereby, productivity can be further increased.

DESCRIPTION OF SYMBOLS 1 ... Elastic wave apparatus 2 ... Piezoelectric substrate 3 ... IDT electrode 3a-3e ... 1st-5th metal layer 4a ... 1st inner side bus-bar 4b ... 1st electrode finger 4c ... 1st connection electrode 5a ... 2nd Inner bus bar 5b ... second electrode finger 5c ...

second connection electrode

6, 7 ... first and second

outer bus bars

8, 9 ... first and

second openings

13a, 13b ...

reflectors

14, 15 ... 1st, 2nd bus bar 16, 17 ...

Wide part

18, 19 ... 1st, 2nd dielectric film 22 ... Resist pattern 23 ... Metal film 33 ...

IDT electrode

34, 35 ... 1st,

2nd bus bar

34c, 35c ... 3rd,

4th connection electrodes

38, 39 ... 3rd,

4th opening

44, 45 ... 1st, 2nd bus bar 44b, 45b ... 1st, 2nd electrode finger 44c, 45c ... first and

second connection electrodes

48, 49 ... first and second openings 51 ... elastic wave device 52 ... both longitudinally coupled Sub-type elastic wave filters 53A to 53C ... 1st to 3rd IDT electrodes 56A to 56C ... 1st outer bus bar 57A to 57C ... 2nd outer bus bar 58 ... Wiring electrode 59a ... Terminal 61 ... Elastic wave devices 62A to 62C ... First to third elastic wave resonators 68 ... Wiring electrodes 104c, 105c ... First and second connection electrodes 114c, 115c ... First, second connection electrodes 118, 119: first and

second openings

124c, 125c ... third and

fourth connection electrodes

134, 135 ... first and second bus bars 134c, 135c ... first and second electrodes

Claims

A first bus bar and a second bus bar facing each other, a plurality of first electrode fingers having one end connected to the first bus bar, one end connected to the second bus bar, and A method of manufacturing an acoustic wave device having an IDT electrode including the plurality of first electrode fingers and a plurality of second electrode fingers interleaved with each other,
Preparing a piezoelectric substrate;
On the piezoelectric substrate, a first inner bus bar, the plurality of first electrode fingers whose one ends are connected to the first inner bus bar, and a second inner bus bar facing the first inner bus bar And a plurality of second electrode fingers whose one ends are connected to the second inner bus bar and a side of the first inner bus bar opposite to the side to which the plurality of first electrode fingers are connected. A plurality of first connection electrodes whose one ends are connected to each other and a plurality of one ends connected to the side of the second inner busbar opposite to the side where the plurality of second electrode fingers are connected Forming a second connection electrode by a lift-off method;
By forming a first outer bus bar on the piezoelectric substrate so as to cover a part of the plurality of first connection electrodes, the first outer bus bar, the plurality of first connection electrodes, and the first Forming the first bus bar having a plurality of first openings surrounded by one inner bus bar;
By forming a second outer bus bar on the piezoelectric substrate so as to cover a part of the plurality of second connection electrodes, the second outer bus bar, the plurality of second connection electrodes, and the second Forming the second bus bar having a plurality of second openings surrounded by two inner bus bars;
A method of manufacturing an acoustic wave device.
In the step of forming the first connection electrode, the first connection electrode is connected to the end of the first connection electrode opposite to the side connected to the first inner bus bar on the piezoelectric substrate. The method of manufacturing an acoustic wave device according to claim 1, wherein a third connection electrode extending in a direction intersecting with a direction in which the first connection electrode extends is formed.
3. The method of manufacturing an acoustic wave device according to claim 2, wherein, in the step of forming the first connection electrode and the third connection electrode, a plurality of the third connection electrodes are formed with a gap therebetween.
In the step of forming the first connection electrode and the third connection electrode, the plurality of third connections surrounded by the third connection electrode, the plurality of first connection electrodes, and the first inner bus bar. The dimension along the direction in which the first connection electrode of the third opening extends so as to form the opening is larger than the dimension along the direction in which the first connection electrode of the first opening extends. The method for manufacturing an acoustic wave device according to claim 2, wherein the third connection electrode is formed to be long.
5. The method according to claim 1, wherein the first connection electrode and the second connection electrode extend in a direction parallel to a direction in which the first electrode finger and the second electrode finger extend. The manufacturing method of the elastic wave apparatus as described in 2 ..
5. The method according to claim 1, wherein the first connection electrode and the second connection electrode extend in a direction intersecting with a direction in which the first electrode finger and the second electrode finger extend. The manufacturing method of the elastic wave apparatus as described in 2 ..
When the elastic wave propagation direction is a first direction and the direction in which the first electrode finger and the second electrode finger extend is a second direction, the IDT electrode is connected to the first electrode finger and the first electrode finger. A crossing region that is a portion where the second electrode finger overlaps in the first direction;
The crossing region is a central region located on the center side in the second direction, and a first edge region and a second edge region disposed on both sides of the central region in the second direction, Have
The first edge region is located on the first inner busbar side, the second edge region is located on the second inner busbar side,
The method of manufacturing an acoustic wave device according to any one of claims 1 to 6, wherein sound velocity in the first edge region and the second edge region is lower than sound velocity in the central region.
Forming a wiring electrode on the piezoelectric substrate so as to be connected to the first outer bus bar;
The method of manufacturing an acoustic wave device according to any one of claims 1 to 7, wherein the step of forming the wiring electrode is performed simultaneously with the step of forming the first outer bus bar.
A step of forming a terminal on the piezoelectric substrate so as to connect to the wiring electrode;
The method for manufacturing an acoustic wave device according to claim 8, wherein the step of forming the terminal is performed simultaneously with the step of forming the first outer bus bar and the wiring electrode.
A piezoelectric substrate;
An IDT electrode provided on the piezoelectric substrate;
With
The IDT electrode includes a first inner bus bar, a plurality of first electrode fingers having one ends connected to the first inner bus bar, a second inner bus bar facing the first inner bus bar, One end connected to the second inner bus bar, and a plurality of second electrode fingers interleaved with the plurality of first electrode fingers, and the plurality of second electrodes of the first inner bus bar. A plurality of first connection electrodes whose one ends are connected to a side opposite to a side to which one electrode finger is connected, and the plurality of second electrode fingers of the second inner bus bar are connected. A plurality of second connection electrodes having one end connected to the side opposite to the side, a first outer bus bar provided on the plurality of first connection electrodes and the piezoelectric substrate, and the first Outer bus bar, the plurality of first connection electrodes and the first inner side A plurality of first openings surrounded by a sbar; a second outer bus bar provided on the plurality of second connection electrodes and the piezoelectric substrate; the second outer bus bar; An elastic wave device comprising: a second connection electrode; and a plurality of second openings surrounded by the second inner bus bar.
11. The acoustic wave according to claim 10, wherein the plurality of first connection electrodes and the second connection electrodes extend in a direction crossing a direction in which the first electrode fingers and the second electrode fingers extend. apparatus.
When the elastic wave propagation direction is a first direction and the direction in which the first electrode finger and the second electrode finger extend is a second direction, the IDT electrode is connected to the first electrode finger and the first electrode finger. A crossing region that is a portion where the second electrode finger overlaps in the first direction;
The IDT electrode has a central region located on the center side in the second direction in the crossing region, a first edge region and a second edge region disposed on both sides of the central region in the second direction. An edge region, and
The first edge region is located on the first inner busbar side, the second edge region is located on the second inner busbar side,
The acoustic wave device according to claim 10 or 11, wherein sound velocity in the first edge region and the second edge region is lower than sound velocity in the central region.
The first outer bus bar is provided on a concavo-convex portion including the plurality of first connection electrodes and the piezoelectric substrate, and the second outer bus bar is formed from the plurality of second connection electrodes and the piezoelectric substrate. The elastic wave device according to any one of claims 10 to 12, which is provided on the uneven portion.