HK1229962B - Acoustic wave elements and ladder filters using same - Google Patents

Description

Acoustic wave element and ladder filter using the same

Technical Field

The present invention relates to an acoustic wave element and a ladder-type filter using the same.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119 and PCT Article 8 of co-pending Japanese Patent Application No. 2014-028059, filed February 18, 2014, entitled “ACOUSTIC WAVE ELEMENTS AND LADDER FILTERS USING SAME,” which is hereby incorporated by reference herein in its entirety for all purposes.

Background Art

Figures 1 and 2 illustrate an example of a conventional acoustic wave element 6000, which can be used in electronic devices such as wireless communication devices. Figure 1 shows a plan view of the conventional acoustic wave element 6000, and Figure 2 shows a corresponding cross-sectional view taken along line B-BB in Figure 1. As shown in Figures 1 and 2, the conventional acoustic wave element 6000 includes a first interdigital transducer (IDT) electrode 1000 and a second IDT electrode 2000, both of which are disposed on the upper surface of a piezoelectric body 5000. The conventional acoustic wave element 6000 also includes a connecting wiring 3000 connecting the first IDT electrode 1000 to the second IDT electrode 2000, and a reinforcing electrode 4000 disposed on the connecting wiring 3000. The reinforcing electrode 4000 is provided to reduce the resistance of the connecting wiring 3000 connecting the first IDT electrode 1000 to the second IDT electrode 2000. In addition, the connecting wiring 3000 includes a lower connecting wiring 3002 and an upper connecting wiring 3001. The upper connecting wiring 3001 is disposed on the upper surface of the lower connecting wiring 3002.

Japanese Patent Application Laid-Open No. 2011-71912 describes an example of such a conventional acoustic wave element.

Citation List

Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2011-71912

Summary of the Invention

Aspects and embodiments of the present application relate to an acoustic wave element and a ladder-type filter using the acoustic wave element.

In conventional acoustic wave elements such as those discussed above with reference to Figures 1 and 2, merely providing a reinforcing electrode on the upper surface of the connection wiring is insufficient to sufficiently reduce electrical loss. Therefore, embodiments of the acoustic wave element according to the present invention can be configured to significantly reduce electrical loss in the connection wiring electrically connected between IDT electrodes, as discussed in more detail below.

According to one embodiment, an acoustic wave element includes a piezoelectric body having an upper surface, an interdigital transducer (IDT) electrode arranged above the piezoelectric body, a connecting wiring arranged above the piezoelectric body and connected to the IDT electrode, and a reinforcing electrode arranged above the connecting wiring, the connecting wiring having a lower connecting wiring and an upper connecting wiring arranged above the lower connecting wiring, the reinforcing electrode contacting and electrically connected to the lower connecting wiring.

In one example of the acoustic wave element, the connecting wiring includes a hole electrode extending perpendicularly to the upper surface of the piezoelectric body, and the reinforcing electrode is electrically connected to the lower connecting wiring via the hole electrode. In one example, the hole electrode extends through the upper connecting wiring and the lower connecting wiring, and a first diameter of the hole electrode in the upper connecting wiring is larger than a second diameter of the hole electrode in the lower connecting wiring.

The material of the lower connection wiring may be different from the material of the upper connection wiring. In particular, the oxygen affinity of the material of the lower connection wiring may be lower than the oxygen affinity of the material of the upper connection wiring.

The reinforcement electrode may contact and be electrically connected to the upper surface of the lower connection wiring. In one example, in a cross section taken in a direction perpendicular to the upper surface of the piezoelectric body, the upper connection wiring is separated by the reinforcement electrode to provide a first and a second upper connection wiring, and the first and the second upper connection wiring are electrically connected to each other via the reinforcement electrode. The acoustic wave element may further include a third connection electrode on the piezoelectric body arranged between the first and the second upper connection wiring, the third connection wiring is covered by an insulating layer, and the reinforcement electrode extends above the insulating layer. In another example, in a cross section taken in a direction perpendicular to the upper surface of the piezoelectric body, the lower connection wiring is separated by the reinforcement electrode to provide a first and a second lower connection wiring, and the first and the second lower connection wiring are electrically connected to each other via the reinforcement electrode. The acoustic wave element may further include a third connection wiring on the piezoelectric body arranged between the first and the second lower connection wiring, the third connection wiring is covered by an insulating layer, and the reinforcement electrode extends above the insulating layer.

In one example, the IDT electrode includes a lower IDT electrode and an upper IDT electrode disposed above the lower IDT electrode. The material of the lower IDT electrode is the same as that of the lower connection wiring, and the material of the upper IDT electrode is the same as that of the upper connection wiring.

According to another embodiment, an acoustic wave element includes a piezoelectric body having an upper surface, a first interdigital transducer (IDT) electrode arranged on the piezoelectric body, a second IDT electrode arranged on the piezoelectric body, a connecting wiring arranged on the upper surface of the piezoelectric body and electrically connected to the first IDT electrode and the second IDT electrode, and a reinforcement electrode arranged above the connecting wiring, the connecting wiring including a lower connecting wiring and an upper connecting wiring arranged above the lower connecting wiring, the reinforcement electrode contacting and electrically connected to the lower connecting wiring.

In one example, the lower connection wiring is formed of a first material, and the upper connection wiring is formed of a second material, and the oxygen affinity of the first material is lower than the oxygen affinity of the second material.

In another example, the reinforcing electrode further contacts and is electrically connected to the upper connecting wiring. The connecting wiring may further include a hole electrode extending through the upper connecting wiring and the lower connecting wiring in a direction perpendicular to the upper surface of the piezoelectric body. In one example, the hole electrode has a first diameter in the upper connecting wiring and a second diameter in the lower connecting wiring, the first diameter being larger than the second diameter. The reinforcing electrode is electrically connected to the lower connecting wiring via the hole electrode.

In another example, in a cross section taken in a direction perpendicular to the upper surface of the piezoelectric body, the connection wiring, including both the upper and lower connection wirings, is separated by the reinforcing electrode to provide first and second connection wirings, and the first and second connection wirings are electrically connected to each other via the reinforcing electrode. The acoustic wave element may further include a third connection wiring disposed on the piezoelectric body between the first and second connection wirings, the third connection wiring being covered by an insulating layer, and the reinforcing electrode extending above the insulating layer.

Another embodiment relates to a ladder-type filter including the acoustic wave element of any of the above examples.

According to another embodiment, an acoustic wave element includes a piezoelectric body having an upper surface, a first interdigital transducer (IDT) electrode arranged on the piezoelectric body, a second IDT electrode arranged on the piezoelectric body, a connecting wiring arranged on the upper surface of the piezoelectric body and electrically connected to the first IDT electrode and the second IDT electrode, and a device for reducing electrical loss in the connecting wiring.

Still other aspects, embodiments, and advantages of these exemplary aspects and embodiments are discussed in detail below. The embodiments disclosed herein may be combined with other embodiments in any manner consistent with at least one of the principles disclosed herein, and references to "an embodiment," "some embodiments," "an alternative embodiment," "various embodiments," "one embodiment," etc. are not necessarily mutually exclusive and are intended to indicate that the particular features, structures, or characteristics being described may be included in at least one embodiment. The appearances of these terms herein do not necessarily all refer to the same embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

Various aspects of at least one embodiment will be discussed below with reference to the accompanying drawings, which are not intended to be drawn to scale. The accompanying drawings are included to provide illustration and further understanding of the various aspects and embodiments, and are incorporated into and constitute a part of this specification, but are not intended to define limitations of the invention. In the drawings, each identical or nearly identical component illustrated in various figures is represented by a like numeral. For clarity, not every component may be labeled in every figure. In the drawings:

FIG1 is a plan view schematically showing an example of a conventional acoustic wave element;

FIG2 is a cross-sectional view of the conventional acoustic wave element of FIG1 taken along line B-BB in FIG1;

3 is a plan view schematically showing an example of an acoustic wave element according to aspects of the present invention;

4A is a cross-sectional view of an example of the acoustic wave element of FIG. 3 taken along line A-AA in FIG. 3 ;

4B is a cross-sectional view of an example of the acoustic wave element of FIG. 3 taken along line A-AA in FIG. 3 ;

4C is a cross-sectional view of an example of the acoustic wave element of FIG. 3 taken along line A-AA in FIG. 3 ;

4D is a cross-sectional view of an example of the acoustic wave element of FIG. 3 taken along line A-AA in FIG. 3 ;

5A is a cross-sectional view of an example of a conventional acoustic wave element, showing measurement conditions of a contact resistance value of a connection wiring;

FIG5B is a corresponding plan view of the exemplary conventional acoustic wave element of FIG5A;

6A is a cross-sectional view of an example of an acoustic wave element according to aspects of the present invention, illustrating measurement conditions of a contact resistance value of a connection wiring;

FIG6B is a corresponding plan view of the example acoustic wave element of FIG6A;

7A is a cross-sectional view of another example of the acoustic wave element according to aspects of the present invention, illustrating measurement conditions of a contact resistance value of a connection wiring;

FIG7B is a corresponding plan view of the example acoustic wave element of FIG7A ;

8 is a characteristic diagram showing measurement results of contact resistance values of connection wiring corresponding to the example of FIGS. 5A to 7B ;

9A is a cross-sectional view of an example of a conventional acoustic wave element, showing measurement conditions of a resistance value per unit length of a connection wiring;

FIG9B is a corresponding plan view of the exemplary conventional acoustic wave element of FIG9A;

10A is a cross-sectional view of an example of an acoustic wave element according to aspects of the present invention, illustrating measurement conditions of a resistance value per unit length of a connection wiring;

FIG10B is a corresponding plan view of the example acoustic wave element of FIG10A;

11A is a cross-sectional view of another example of the acoustic wave element according to aspects of the present invention, illustrating measurement conditions of a resistance value per unit length of a connection wiring;

FIG11B is a corresponding plan view of the example acoustic wave element of FIG11A;

12 is a characteristic diagram showing measurement results of resistance values of connection wiring corresponding to the example of FIGS. 9A-11B ;

FIG13 is a circuit diagram of an example of a ladder-type filter according to aspects of the present invention; and

FIG. 14 is a characteristic diagram illustrating pass characteristics of a ladder-type filter according to aspects of the present invention.

DETAILED DESCRIPTION

Certain aspects and embodiments will be described below with reference to the accompanying drawings and an exemplary acoustic wave element 60 .

Fig. 3 is a plan view schematically illustrating an embodiment of the acoustic wave element 60. Figs. 4A-4D are cross-sectional views of various examples of the acoustic wave element 60 taken along line A-AA in Fig. 3 .

According to one embodiment, an acoustic wave element 60 includes a piezoelectric body 50 made of a single crystal piezoelectric material. A first IDT electrode 10 and a second IDT electrode 20 are disposed on the upper surface of the piezoelectric body 50. The acoustic wave element 60 also includes two reflectors 13 disposed adjacent to the IDT electrodes 10 and 20 in the direction of propagation of the acoustic waves generated by the first and second IDT electrodes 10 and 20. The acoustic wave element 60 also includes a connection wiring 30 electrically connecting the first and second IDT electrodes 10 and 20, and a reinforcing electrode 40 disposed on the upper surface of the connection wiring 30 to reduce electrical loss in the connection wiring 30. The first IDT electrode 10 has a comb-shaped electrode structure, each of which includes a linear first bus bar 12 and a plurality of first electrode fingers 11 extending perpendicularly to the linear direction of the linear first bus bar 12. The first IDT electrode 10 is formed of opposing comb-shaped electrodes. Similar to the first IDT electrode 10, the second IDT electrode 20 has a comb-shaped electrode structure, each of which includes a second bus bar 22 and a plurality of second electrode fingers 21. The first IDT electrode 10, the second IDT electrode 20, the reflector 13, the connection wiring 30, and the reinforcing electrode 40 can be formed by patterning a metallic thin film. Although not shown in the figures, those skilled in the art will appreciate that, with the benefit of this disclosure, by providing a dielectric layer covering the upper surfaces of the piezoelectric body 50, the first IDT electrode 10, the second IDT electrode 20, the reflector 13, the connection wiring 30, and the reinforcing electrode 40, the acoustic wave element 60 according to certain embodiments can achieve improved temperature characteristics.

In one embodiment, the connection wiring 30 includes an upper connection wiring 31 and a lower connection wiring 32. The lower connection wiring 32 and the reinforcement electrode 40 are in contact with each other and electrically connected, thereby significantly reducing the electrical loss in the connection wiring 30. When the oxide film formed on the surface of the upper connection wiring 31 and the lower connection wiring 32 during thin film processing blocks the electrical connection between the connection wiring 30 and the reinforcement electrode 40, electrical loss is generated. In other words, due to the presence of the oxide film, the effect of reducing the resistance of the connection wiring 30 achieved by providing the reinforcement electrode 40 is lost or deteriorated. In view of the above reasons, certain aspects and embodiments solve the problem of the oxide film formed on the surface of the connection wiring 30, and reduce the electrical loss in the connection wiring 30 by reducing the contact resistance between the connection wiring 30 and the reinforcement electrode 40.

According to one embodiment, the material forming the upper connection wiring 31 and the lower connection wiring 32 may preferably be a material that is not prone to forming an oxide film on the surface. Generally, susceptibility to oxidation is represented by oxygen affinity. In addition, because the main reason for the electric loss reduction effect in the connection wiring 30 in one embodiment lies in the structure in which the lower connection wiring 32 and the reinforcement electrode 40 are in contact with each other and electrically connected, it is preferable that the oxygen affinity of the material forming the lower connection wiring 32 is smaller than the oxygen affinity of the material forming the upper connection wiring 31. The oxygen affinity of a material is generally associated with the standard free energy, and the smaller the standard free energy (ΔG/kJmol ^-1 ), the smaller the oxygen affinity. Representative materials are listed below in ascending order of standard free energy:

Pt<Ru<Cu<Mo≈W<<Ti<Al<Mg.

It will be understood that although a two-layer structure of the upper and lower connection wirings 31 and 32 is described in at least one embodiment, the structure is not limited to two layers and may be configured with three or more layers.

The structures of the connection wiring 30 and the reinforcing electrode 40 according to some embodiments will be described in detail below with reference to FIGS. 4A-4D .

As shown in Figures 4A-4D, according to certain embodiments, among the connection wiring 30, at least the lower connection wiring 32 and the reinforcing electrode 40 are in contact with each other and electrically connected. The lower connection wiring 32, the upper connection wiring 31, and the reinforcing electrode 40 are sequentially arranged on the upper surface of the piezoelectric body 50. Furthermore, the connection wiring 30 can be formed simultaneously with the first IDT electrode 10 and the second IDT electrode 20 using thin film processing. Furthermore, it is preferable to use the same structure (e.g., a two-layer structure) and the same materials to simplify the manufacturing process.

4A , in one embodiment, the upper connection wiring 31 is separated by a reinforcing electrode 40, and the upper surface of the lower connection wiring 32 is in contact with and electrically connected to the reinforcing electrode 40. Furthermore, the upper surface and side surfaces of the upper connection wiring 31 are in contact with and electrically connected to the reinforcing electrode 40.

4B , in another embodiment, in addition to the characteristics of the example shown in FIG 4A , the lower connection wiring 32 is also separated by the reinforcing electrode 40, and the piezoelectric body 50 also has a surface in contact with the reinforcing electrode 40. The reinforcing electrode 40 may be characterized by a structure in contact with and electrically connected to the side surface of the lower connection wiring 32.

Referring to FIG. 4C , according to another embodiment, a hole electrode 70 is provided that extends through the upper and lower connecting wirings 31 and 32 in a direction perpendicular to the upper surface of the piezoelectric body 50, thereby bringing the lower connecting wiring 32 and the reinforcing electrode 40 into contact and electrically connected. Furthermore, with respect to a cross-section of the hole electrode 70 taken in a direction parallel to the upper surface of the piezoelectric body 50, it is preferable to make the cross-sectional area of the hole electrode 70 provided in the lower connecting wiring 32 smaller than the cross-sectional area of the hole electrode 70 provided in the upper connecting wiring 31. This allows not only the side surfaces of the lower connecting wiring 32 but also its upper surface to contact and be electrically connected to the reinforcing electrode 40. As a result, the contact area is increased, further reducing the contact resistance.

It will be understood that the shape of the hole electrode 70 is not limited to the example shown in FIG4C , but may have any cross-sectional shape, including, for example, a circular shape, a rectangular shape, etc. In addition, the cross-section may be configured differently in the depth direction of the hole electrode 70. It will also be understood that, although not shown in the drawings, the hole electrode 70 may be provided only in the upper connection wiring 31 so that the upper surface of the lower connection wiring 32 contacts and is electrically connected to the hole electrode 70.

Referring to Figure 4D, it shows another structure of the connection wiring according to some examples. In this structure, when a connection wiring 30 separated by the reinforcing electrode 40 is designated as the first connection wiring 100 and the other connection wiring 30 is designated as the second connection wiring 110, the third connection wiring 120 is arranged on the upper surface of the piezoelectric body 50 between the first connection wiring 100 and the second connection wiring 110. The third connection wiring 120 is covered by an insulating layer 80. As a characteristic structure, the reinforcing electrode 40 is three-dimensionally crossed with the upper part of the third connection wiring 120 via the insulating layer 80, and is in contact with and electrically connected to the first connection wiring 100 and the second connection wiring 110. The third connection wiring 120 can be an electrode having a different potential from the first connection wiring 100 or the second connection wiring 110. In one example, the third connection wiring 120 can be integrated with the first connection wiring 100 and the second connection wiring 110 and formed simultaneously. It is preferred to adopt the same structure (for example, a two-layer structure) and the same material to simplify the manufacturing process.

5A-7B , the embodiment of the acoustic wave element 60 will be compared with a conventional acoustic wave element to describe the contact resistance between the connection wiring 30 and the reinforcing electrode 40 , which shows an example of measuring the contact resistance in the connection wiring 30 and the reinforcing electrode 40 .

5A and 5B are a cross-sectional view and a plan view, respectively, corresponding to the structure of the conventional acoustic wave element of Fig. 2. Figs. 5A and 5B show a comparative example in which the reinforcing electrode 40 contacts and is electrically connected to only the upper connection wiring 31. In the example of Figs.

6A and 6B respectively illustrate a cross-sectional view and a corresponding plan view of an example of an embodiment of an acoustic wave element 60 in which both the upper connection wiring 31 and the lower connection wiring 32 are in contact with and electrically connected to each other.

7A and 7B respectively illustrate a cross-sectional view and a corresponding plan view of another example of an embodiment of an acoustic wave element 60 in which only the lower connection wiring 32 contacts and is electrically connected to the reinforcement electrode 40 .

For each of these examples, the reinforcing electrode 40 was made of aluminum (Al), the upper connection wiring 31 was made of aluminum alloy, the lower connection wiring 32 was made of molybdenum (Mo), and the total contact area between the reinforcing electrode 40 and the connection wiring 30 was 400 μm ² .

Figure 8 shows the measurement results of the contact resistance per unit area between the connecting wiring 30 and the reinforcing electrode 40. In Figure 8, five measurement points are plotted for each of Figures 5A-7B. As shown in Figure 8, the contact resistance per unit area of the embodiment of Figures 6A-6B and 7A-7B is lower than the contact resistance per unit area of the comparative example of Figures 5A-5B. This is because the oxide film formed on the upper surface of the upper connecting wiring 31 during thin film processing increases the contact resistance per unit area between the reinforcing electrode 40 and the connecting wiring 30. In addition, the contact resistance per unit area of the embodiment of Figures 7A-7B is lower than the contact resistance per unit area of the embodiment of Figures 5A-5B and 6A-6B. This is because the oxygen affinity of the lower connecting wiring 32 (Mo) is less than that of the upper connecting wiring 31 (Al alloy), making the oxide film less likely to form. In addition, comparing the measured values of the contact resistance per unit area shows that the measured values of the embodiment of Figures 6A-6B and 7A-7B are less variable and more stable than the comparative example of Figures 5A-5B. Furthermore, the variation in the embodiment of Figures 7A-7B is smaller than that of the embodiment of Figures 6A-6B. This indicates that the larger the contact area between the reinforcing electrode 40 and the upper connecting wiring 31, on which an oxide film may have formed, the greater the variation in the measured value of the contact resistance. Therefore, according to certain embodiments, configuring the connecting wiring 30 so that at least the lower connecting wiring 32 contacts and is electrically connected to the reinforcing electrode 40 reduces the contact resistance between the connecting wiring 30 and the reinforcing electrode 40. As a result, electrical loss in the connecting wiring 30 can be reduced.

An example of the resistance value per unit length of the connection wiring 30 will be described below by comparing another embodiment of the acoustic wave element 60 with a conventional acoustic wave element with reference to Figures 9A-11B. Figures 9A-11B illustrate an example of measuring the resistance value per unit length of the connection wiring 30. The connection wiring structure and the constituent materials of each structure are similar to those shown in Figure 4 and described above. The lower connection wiring 32 is provided on the upper surface of the piezoelectric body 50, and the reinforcing electrode 40 is in turn provided on the upper surface of the lower connection wiring 32.

9A and 9B respectively illustrate a cross-sectional view and a corresponding plan view of a comparative example in which there is no contact between the reinforcing electrode 40 and the lower connection wiring 32. The cross-sectional view of FIG10A and the corresponding plan view of FIG10B illustrate an example embodiment in which the hole electrode 70 has a diameter of 8 μm and extends through the upper connection wiring 31 and the lower connection wiring 32. The hole electrode 70 is filled with the reinforcing electrode 40, and the side surface of the reinforcing electrode 40 and the lower connection wiring 32 are electrically connected to each other via the hole electrode 70.

FIG12 shows the results of measuring the resistance per unit length of the connection wiring 30. As shown in FIG12, the resistance per unit length of the connection wiring 30 of the exemplary embodiment shown in FIG10A-10B is lower than the resistance per unit length of the connection wiring 30 of the comparative example shown in FIG9A-9B. Lower connection wiring 32 and reinforcing electrode 40 can be in contact with and electrically connected to each other even over a small area, resulting in reduced electrical loss in the connection wiring 30.

11A and 11B respectively illustrate a cross-sectional view and a plan view of another structure in which the hole electrode 70 is filled with the reinforcing electrode 40 and is provided only in the upper connection wiring 31 so that the reinforcing electrode 40 contacts and is electrically connected to the upper surface of the lower connection wiring 32. Compared to the comparative example of FIGS. 9A-9B , this structure can also reduce the resistance value per unit length of the connection wiring 30 and can also achieve the effect of reducing electrical loss in the connection wiring 30.

It will be understood that the diameter of the hole electrode 70 is not limited to the above-mentioned example of 8 μm, and the effect of reducing electrical loss can be achieved by the lower connection wiring 32 and the reinforcing electrode 40 being in contact and electrically connected to each other.

Pass characteristics of the ladder-type filter of the embodiment using the acoustic wave element 60 and a ladder-type filter using the conventional acoustic wave element 6000 are described below.

FIG13 is a circuit diagram of an example of a ladder filter 400 using an embodiment of an acoustic wave element 60. As shown in FIG13, the ladder filter 400 according to one embodiment includes a first series resonator 301, a second series resonator 302, a third series resonator 303, and a fourth series resonator 304 connected in series between an input terminal 201 and an output terminal 202. A first parallel resonator 305 and a second parallel resonator 306 are connected between the first series resonator 301 and the second series resonator 302 at one end and connected to ground at the other end. A third parallel resonator 307 and a fourth parallel resonator 308 are connected between the third series resonator 303 and the fourth series resonator 304 at one end and connected to ground at the other end. Each of the resonators 301, 302, 303, 304, 305, 306, 307, and 308 may include an acoustic wave element 60.

According to an embodiment, both ends of each IDT electrode of the resonator of the ladder filter 400 are provided with hole electrodes 70 at a single location, as shown in FIG10B, while the comparative example is manufactured without the hole electrodes 70. The transmission characteristics of each ladder filter are compared in FIG14.

14 shows a measurement result of pass characteristics in the ladder-type filter 400. As shown in FIG14, the ladder-type filter of the example embodiment can enhance the attenuation amount in the passband and reduce the minimum insertion loss in the passband relative to the comparative example.

Embodiments of the acoustic wave elements discussed herein are useful in ladder-type filter structures and/or various electronic devices such as cellular telephones.

Having described several aspects of at least one embodiment above, it will be appreciated that various alternatives, modifications, and improvements will readily occur to those skilled in the art. Such alternatives, modifications, and improvements are intended to be part of this disclosure and are intended to fall within the scope of the present invention. Therefore, the embodiments of the methods and apparatus disclosed herein are not limited in their application to the details of construction and arrangement of components described above or illustrated in the accompanying drawings. The methods and apparatus can be implemented in other embodiments and practiced and carried out in various ways. Examples of specific implementations are provided herein for illustrative purposes only and are not intended to be limiting. Furthermore, the phrases and terms used herein are used for descriptive purposes and should not be construed as limiting. As used herein, "includes," "comprising," "having," "containing," "involving," and variations thereof are intended to encompass the items listed thereafter and their equivalents, as well as additional items. References to "or" are to be construed as inclusive, such that any term described with "or" may refer to any one, more than one, or all of the items described. It will also be understood that terms indicating perpendicular directions, parallel directions, depth directions, and the like are used for descriptive purposes to illustrate various aspects of the present invention. Therefore, these terms do not specify absolute directions and are not intended to be limiting. The foregoing description and drawings are by way of example only, and the scope of the present invention should be determined from a proper interpretation of the appended claims and their equivalents.

Claims (20)

1. An acoustic wave element, comprising: A piezoelectric material with a top surface; Interdigitated transducer (IDT) electrodes disposed on the piezoelectric body; Connection wiring disposed on the piezoelectric element and electrically connected to the IDT electrode, the connection wiring including a lower connection wiring, an upper connection wiring disposed above the lower connection wiring, and a via electrode extending through the upper connection wiring and the lower connection wiring in a direction perpendicular to the upper surface of the piezoelectric element, wherein the first diameter of the via electrode in the upper connection wiring is larger than the second diameter of the via electrode in the lower connection wiring; and A reinforcing electrode is disposed above the connection wiring, the reinforcing electrode being in contact with and electrically connected to the lower connection wiring via the hole electrode. 2. The acoustic wave element as claimed in claim 1, wherein the material of the lower connecting wire is different from the material of the upper connecting wire. 3. The acoustic wave element as claimed in claim 2, wherein the oxygen affinity of the material of the lower connecting wire is less than the oxygen affinity of the material of the upper connecting wire. 4. The acoustic element of claim 1, wherein the reinforcing electrode contacts and is electrically connected to the upper surface of the lower connection wiring. 5. The acoustic wave element of claim 4, wherein, in a cross-section taken along a direction perpendicular to the upper surface of the piezoelectric body, the upper connection wiring is separated by the reinforcing electrode to provide first and second upper connection wirings, the first and second upper connection wirings being electrically connected to each other via the reinforcing electrode. 6. The acoustic wave element of claim 5, wherein, in a cross-section taken along a direction perpendicular to the upper surface of the piezoelectric body, the lower connection wiring is separated by the reinforcing electrode to provide first and second lower connection wirings, the first and second lower connection wirings being electrically connected to each other via the reinforcing electrode. 7. The acoustic wave element of claim 4, wherein, in a cross-section taken along a direction perpendicular to the upper surface of the piezoelectric body, the connecting wiring, including both the upper connecting wiring and the lower connecting wiring, is separated by the reinforcing electrode to provide first and second connecting wirings, the first and second connecting wirings being electrically connected to each other via the reinforcing electrode. 8. The acoustic element of claim 7, further comprising a third connecting wire disposed on the piezoelectric body between the first and second connecting wires, the third connecting wire being covered by an insulating layer, the reinforcing electrode extending over the insulating layer. 9. The acoustic wave element as claimed in claim 1, wherein the IDT electrode includes a lower IDT electrode and an upper IDT electrode disposed above the lower IDT electrode, the material of the lower IDT electrode is the same as the material of the lower connecting wiring, and the material of the upper IDT electrode is the same as the material of the upper connecting wiring. 10. A trapezoidal filter comprising the acoustic element of any one of claims 1-9. 11. An acoustic wave element, comprising: A piezoelectric material with a top surface; The first interdigital transducer (IDT) electrode is disposed on the piezoelectric body; A second IDT electrode is disposed on the piezoelectric body; Connection wiring disposed on the upper surface of the piezoelectric element and electrically connected to the first IDT electrode and the second IDT electrode, the connection wiring including a lower connection wiring, an upper connection wiring disposed above the lower connection wiring, and an aperture electrode extending through the upper connection wiring and the lower connection wiring in a direction perpendicular to the upper surface of the piezoelectric element, the aperture electrode having a first diameter in the upper connection wiring and a second diameter in the lower connection wiring, the first diameter being larger than the second diameter; and A reinforcing electrode is disposed above the connection wiring, the reinforcing electrode being in contact with and electrically connected to the upper connection wiring and via the hole electrode being in contact with and electrically connected to the lower connection wiring. 12. The acoustic element of claim 11, wherein the lower connecting wire is formed of a first material, the upper connecting wire is formed of a second material, and the oxygen affinity of the first material is less than that of the second material. 13. The acoustic element of claim 11, wherein, in a cross-section taken along a direction perpendicular to the upper surface of the piezoelectric body, the connecting wiring, including both the upper connecting wiring and the lower connecting wiring, is separated by the reinforcing electrode to provide first and second connecting wirings, the first and second connecting wirings being electrically connected to each other via the reinforcing electrode. 14. The acoustic element of claim 13, further comprising a third connecting wire disposed on the piezoelectric body between the first and second connecting wires, the third connecting wire being covered by an insulating layer, the reinforcing electrode extending over the insulating layer. 15. A trapezoidal filter comprising the acoustic element according to any one of claims 11-14. 16. An acoustic wave element, comprising: A piezoelectric material with a top surface; Interdigitated transducer (IDT) electrodes disposed on the piezoelectric body; Connection wiring disposed on the piezoelectric element and electrically connected to the IDT electrode, the connection wiring including a lower connection wiring and an upper connection wiring disposed above the lower connection wiring; and A reinforcing electrode is disposed above the connecting wire, the reinforcing electrode contacting and electrically connected to the upper surface of the lower connecting wire, and in a cross-section taken in a direction perpendicular to the upper surface of the piezoelectric body, the upper connecting wire is separated by the reinforcing electrode to provide first and second upper connecting wires, the first and second upper connecting wires being electrically connected to each other via the reinforcing electrode. 17. The acoustic wave element of claim 16, wherein, in a cross-section taken along a direction perpendicular to the upper surface of the piezoelectric body, the lower connection wiring is separated by the reinforcing electrode to provide first and second lower connection wirings, the first and second lower connection wirings being electrically connected to each other via the reinforcing electrode. 18. The acoustic element of claim 17, further comprising additional connecting wiring disposed on the piezoelectric element between the first and second lower connecting wirings and between the first and second upper connecting wirings, the additional connecting wirings being covered by an insulating layer, the reinforcing electrode extending over the insulating layer. 19. The acoustic element of claim 16, wherein the connection wiring includes a hole electrode extending in a direction perpendicular to the upper surface of the piezoelectric body, and the reinforcing electrode is electrically connected to the lower connection wiring via the hole electrode. 20. The acoustic element of claim 19, wherein the aperture electrode extends through the upper connection wiring and the lower connection wiring, and the first diameter of the aperture electrode in the upper connection wiring is greater than the second diameter of the aperture electrode in the lower connection wiring.