阅读说明：本技术 弹性波装置 (Elastic wave device ) 是由 铃木孝尚 宫本幸治 于 2018-10-19 设计创作，主要内容包括：本发明提供一种能够在抑制活塞模式的阻碍的同时谋求ESD耐性的提高的弹性波装置。弹性波装置(1)具备：压电体部(24)；IDT电极(3),与第1端子(11)和第2端子(12)连接；和反射器(8),与第2端子(12)连接。在IDT电极(3)中,在将IDT电极(3)中一组电极指之中在第2方向(D2)上位于一端的电极指设为第1端电极指,将位于另一端的电极指设为第2端电极指的情况下,第1端电极指在第2方向(D2)上位于反射器(8)与第2端电极指之间。第1汇流条(4)和第2汇流条(5)之中不与第1端电极指连接的汇流条的外侧汇流条部在第2方向(D2)上位于比第1端电极指的第1方向(D1)的中央部更靠内侧。(The invention provides an elastic wave device which can inhibit obstruction of a piston mode and improve ESD resistance. An elastic wave device (1) is provided with: a piezoelectric body (24); an IDT electrode (3) connected to the 1 st terminal (11) and the 2 nd terminal (12); and a reflector (8) connected to the 2 nd terminal (12). In the IDT electrode (3), when an electrode finger positioned at one end in the 2 nd direction (D2) among a group of electrode fingers in the IDT electrode (3) is set as a1 st end electrode finger, and an electrode finger positioned at the other end is set as a2 nd end electrode finger, the 1 st end electrode finger is positioned between the reflector (8) and the 2 nd end electrode finger in the 2 nd direction (D2). The outer bus bar portion of the bus bar not connected to the 1 st terminal electrode finger among the 1 st bus bar (4) and the 2 nd bus bar (5) is located more inward in the 2 nd direction (D2) than the center portion of the 1 st terminal electrode finger in the 1 st direction (D1).)

1. An elastic wave device is provided with:

a1 st terminal;

a2 nd terminal having a potential lower than that of the 1 st terminal;

a piezoelectric body;

an IDT electrode provided on the piezoelectric body and electrically connected to the 1 st terminal and the 2 nd terminal; and

a reflector disposed on the piezoelectric body and electrically connected to the No. 2 terminal,

the IDT electrode has:

a1 st bus bar electrically connected to the 1 st terminal;

a2 nd bus bar facing the 1 st bus bar in a1 st direction and electrically connected to the 2 nd terminal;

a plurality of 1 st electrode fingers connected to the 1 st bus bar and extending from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction; and

a plurality of 2 nd electrode fingers connected to the 2 nd bus bar and extending from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction,

the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction,

at least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger,

the 1 st bus bar and the 2 nd bus bar each include:

an opening part;

an inner busbar portion located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction;

an outer busbar portion located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction; and

a connecting portion that connects the inner busbar portion and the outer busbar portion in the 1 st direction,

in the IDT electrode, an electrode finger located at one end in the 2 nd direction among a group of electrode fingers including the 1 st electrode finger and the 2 nd electrode fingers is set as a1 st end electrode finger, and an electrode finger located at the other end is set as a2 nd end electrode finger, in which case the 1 st end electrode finger is located between the reflector and the 2 nd end electrode finger in the 2 nd direction,

an outer bus bar portion of a bus bar not connected to the 1 st terminal electrode finger among the 1 st bus bar and the 2 nd bus bar is located more inward in the 2 nd direction than a central portion of the 1 st terminal electrode finger in the 1 st direction.

2. The elastic wave device according to claim 1,

the reflector is provided with two of the reflectors,

the two reflectors are disposed one each at two adjacent positions of the IDT electrode in the 2 nd direction,

an outer bus bar portion of a bus bar, which is not connected to the 1 st end electrode finger and the 2 nd end electrode finger, of the 1 st bus bar and the 2 nd bus bar is located more inward in the 2 nd direction than the wide width portion of the 1 st end electrode finger and the wide width portion of the 2 nd end electrode finger.

3. The elastic wave device according to claim 1,

the reflector is provided with two of the reflectors,

the two reflectors are disposed one each at two adjacent positions of the IDT electrode in the 2 nd direction,

an outer bus bar portion of a bus bar, which is not connected to the 1 st end electrode finger and the 2 nd end electrode finger, of the 1 st bus bar and the 2 nd bus bar is located more inward than the 1 st end electrode finger and the 2 nd end electrode finger in the 2 nd direction so as not to overlap with the 1 st end electrode finger and the 2 nd end electrode finger, respectively, in the 1 st direction.

4. The elastic wave device according to claim 3,

one side of the inner bus bar portion of the bus bar, which is not connected to the 1 st and 2 nd terminal electrode fingers, of the 1 st and 2 nd bus bars along the 1 st direction and the side of the wide portion of the 1 st terminal electrode finger opposite to the 2 nd terminal electrode finger side are aligned in a straight line.

5. An elastic wave device is provided with:

a1 st terminal;

a2 nd terminal having a potential lower than that of the 1 st terminal;

a piezoelectric body;

a plurality of IDT electrodes provided on the piezoelectric body and electrically connected to the 1 st terminal and the 2 nd terminal; and

two reflectors provided on the piezoelectric body portion and reflecting elastic waves excited by the plurality of IDT electrodes,

the plurality of IDT electrodes each have:

1 st bus bar;

a2 nd bus bar opposed to the 1 st bus bar in a1 st direction;

a plurality of 1 st electrode fingers connected to the 1 st bus bar and extending from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction; and

a plurality of 2 nd electrode fingers connected to the 2 nd bus bar and extending from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction,

the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers are arranged in a2 nd direction orthogonal to the 1 st direction with a space therebetween,

at least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger,

the 1 st bus bar and the 2 nd bus bar each include:

an opening part;

an inner busbar portion located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction;

an outer busbar portion located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction; and

a connecting portion that connects the inner busbar portion and the outer busbar portion in the 1 st direction,

the plurality of IDT electrodes are arranged in the 2 nd direction,

the two reflectors are located on the opposite side of each of IDT electrodes on both sides among the plurality of IDT electrodes arranged in the 2 nd direction from the adjacent IDT electrode,

in an IDT electrode adjacent to one of the two reflectors among the plurality of IDT electrodes, an electrode finger located at one end in the 2 nd direction among a group of electrode fingers including the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers is set as a1 st end electrode finger, and an electrode finger located at the other end is set as a2 nd end electrode finger, in which case the 1 st end electrode finger is located between the one reflector and the 2 nd end electrode finger in the 2 nd direction,

in the IDT electrode adjacent to the one reflector, an outer bus bar portion of a bus bar not connected to the 1 st end electrode finger among the 1 st bus bar and the 2 nd bus bar is located more inward in the 2 nd direction than a central portion in the 1 st direction of the 1 st end electrode finger.

6. The elastic wave device according to claim 5,

in the IDT electrode adjacent to the one reflector, an outer bus bar portion of a bus bar, which is not connected to the 1 st end electrode finger and the 2 nd end electrode finger, of the 1 st bus bar and the 2 nd bus bar is located more inward than the wide width portion of each of the 1 st end electrode finger and the 2 nd end electrode finger in the 2 nd direction.

7. The elastic wave device according to claim 5,

in the IDT electrode adjacent to the one reflector, outer bus bar portions of bus bars, among the 1 st bus bar and the 2 nd bus bar, which are not connected to the 1 st end electrode finger and the 2 nd end electrode finger are located inward in the 2 nd direction so as not to overlap with the 1 st end electrode finger and the 2 nd end electrode finger, respectively, in the 1 st direction.

8. The elastic wave device according to claim 7,

in the IDT electrode adjacent to the one reflector, the edge on the one reflector side of the inner bus bar portion of the bus bar not connected to the 1 st end electrode finger and the 2 nd end electrode finger, out of the 1 st bus bar and the 2 nd bus bar, and the edge on the one reflector side of the wide width portion of the 1 st end electrode finger are aligned in a straight line.

9. An elastic wave device is provided with:

a1 st terminal;

a2 nd terminal having a potential lower than that of the 1 st terminal;

a piezoelectric body;

an IDT electrode provided on the piezoelectric body and electrically connected to the 1 st terminal and the 2 nd terminal; and

a reflector disposed on the piezoelectric body and electrically connected to the No. 2 terminal,

the IDT electrode has:

a1 st bus bar electrically connected to the 1 st terminal;

a2 nd bus bar facing the 1 st bus bar in a1 st direction and electrically connected to the 2 nd terminal;

a plurality of 1 st electrode fingers connected to the 1 st bus bar and extending from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction; and

a plurality of 2 nd electrode fingers connected to the 2 nd bus bar and extending from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction,

the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction,

at least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger,

the 1 st bus bar and the 2 nd bus bar each include:

an opening part;

an inner busbar portion located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction;

an outer busbar portion located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction; and

a connecting portion that connects the inner busbar portion and the outer busbar portion in the 1 st direction,

in the IDT electrode, an electrode finger located at one end in the 2 nd direction among a group of electrode fingers including the 1 st electrode finger and the 2 nd electrode fingers is set as a1 st end electrode finger, and an electrode finger located at the other end is set as a2 nd end electrode finger, in which case the 1 st end electrode finger is located between the reflector and the 2 nd end electrode finger in the 2 nd direction,

an outer bus bar portion of a bus bar not connected to the 1 st terminal electrode finger among the 1 st bus bar and the 2 nd bus bar is located more inside in the 2 nd direction than an inner bus bar portion of a bus bar not connected to the 1 st terminal electrode finger.

10. An elastic wave device is provided with:

a1 st terminal;

a2 nd terminal having a potential lower than that of the 1 st terminal;

a piezoelectric body;

a plurality of IDT electrodes provided on the piezoelectric body and electrically connected to the 1 st terminal and the 2 nd terminal; and

two reflectors provided on the piezoelectric body portion and reflecting elastic waves excited by the plurality of IDT electrodes,

the plurality of IDT electrodes each have:

1 st bus bar;

a2 nd bus bar opposed to the 1 st bus bar in a1 st direction;

a plurality of 1 st electrode fingers connected to the 1 st bus bar and extending from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction; and

a plurality of 2 nd electrode fingers connected to the 2 nd bus bar and extending from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction,

the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction,

at least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger,

the 1 st bus bar and the 2 nd bus bar each include:

an opening part;

an inner busbar portion located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction;

an outer busbar portion located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction; and

a connecting portion that connects the inner busbar portion and the outer busbar portion in the 1 st direction,

the plurality of IDT electrodes are arranged in the 2 nd direction,

the two reflectors are located on the opposite side of each of IDT electrodes on both sides among the plurality of IDT electrodes arranged in the 2 nd direction from the adjacent IDT electrode,

in an IDT electrode adjacent to one of the two reflectors among the plurality of IDT electrodes, an electrode finger located at one end in the 2 nd direction among a group of electrode fingers including the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers is set as a1 st end electrode finger, and an electrode finger located at the other end is set as a2 nd end electrode finger, in which case the 1 st end electrode finger is located between the one reflector and the 2 nd end electrode finger in the 2 nd direction,

in the IDT electrode adjacent to the one reflector, an outer bus bar portion of a bus bar not connected to the 1 st end electrode finger among the 1 st bus bar and the 2 nd bus bar is located more inward in the 2 nd direction than an inner bus bar portion of a bus bar not connected to the 1 st end electrode finger.

11. An elastic wave device is provided with:

a1 st terminal;

a2 nd terminal having a potential lower than that of the 1 st terminal;

a piezoelectric body; and

a plurality of IDT electrodes provided on the piezoelectric body and electrically connected to the 1 st terminal and the 2 nd terminal,

the plurality of IDT electrodes each have:

1 st bus bar;

a2 nd bus bar opposed to the 1 st bus bar in a1 st direction;

a plurality of 1 st electrode fingers connected to the 1 st bus bar and extending from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction; and

a plurality of 2 nd electrode fingers connected to the 2 nd bus bar and extending from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction,

the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction,

at least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger,

the 1 st bus bar and the 2 nd bus bar each include:

an opening part;

an inner busbar portion located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction;

an outer busbar portion located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction; and

a connecting portion that connects the inner busbar portion and the outer busbar portion in the 1 st direction,

when one of two IDT electrodes adjacent to each other in the 2 nd direction among the plurality of IDT electrodes is set as a1 st IDT electrode and the other is set as a2 nd IDT electrode,

the interval between the outer busbar portion of the 1 st IDT electrode not connected to the electrode finger closest to the 2 nd IDT electrode among the pair of electrode fingers including the 1 st electrode finger and the 2 nd electrode finger, and the outer busbar portion of the 2 nd IDT electrode not connected to the electrode finger closest to the 1 st IDT electrode among the pair of electrode fingers including the 1 st electrode finger and the 2 nd electrode finger is larger than the interval between the center portion of the electrode finger closest to the 2 nd IDT electrode among the 1 st IDT electrode and the center portion of the electrode finger closest to the 1 st IDT electrode among the 2 nd IDT electrodes.

12. An elastic wave device is provided with:

a1 st terminal;

a2 nd terminal having a potential lower than that of the 1 st terminal;

a piezoelectric body; and

a plurality of IDT electrodes provided on the piezoelectric body and electrically connected to the 1 st terminal and the 2 nd terminal,

the plurality of IDT electrodes each have:

1 st bus bar;

a2 nd bus bar opposed to the 1 st bus bar in a1 st direction;

a plurality of 1 st electrode fingers connected to the 1 st bus bar and extending from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction; and

a plurality of 2 nd electrode fingers connected to the 2 nd bus bar and extending from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction,

the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction,

at least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger,

the 1 st bus bar and the 2 nd bus bar each include:

an opening part;

an inner busbar portion located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction;

an outer busbar portion located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction; and

a connecting portion that connects the inner busbar portion and the outer busbar portion in the 1 st direction,

when one of two IDT electrodes adjacent to each other in the 2 nd direction among the plurality of IDT electrodes is set as a1 st IDT electrode and the other is set as a2 nd IDT electrode,

setting an electrode finger at an end located on the 2 nd IDT electrode side in the 2 nd direction among a group of electrode fingers including the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers of the 1 st IDT electrode as a1 st electrode finger of the 1 st IDT electrode, an electrode finger at an end located on the opposite side to the 2 nd IDT electrode as a2 nd electrode finger of the 1 st IDT electrode, an electrode finger at an end located on the 1 st IDT electrode side in the 2 nd direction among the plurality of 1 st electrode fingers and the group of electrode fingers including the plurality of 2 nd IDT electrode as a1 st electrode finger of the 2 nd IDT electrode, and an electrode finger at an end located on the opposite side to the 1 st IDT electrode as a2 nd electrode finger of the 2 nd IDT electrode, in this case,

the 1 st end electrode finger of the 1 st IDT electrode is connected to the 1 st terminal,

the 1 st end electrode finger of the 2 nd IDT electrode is connected to the 2 nd terminal,

in each of the 1 st IDT electrode and the 2 nd IDT electrode, an outer bus bar portion electrically connected to a terminal other than the 1 st end electrode finger among the 1 st terminal and the 2 nd terminal is located more inward than the inner bus bar portion electrically connected to a terminal other than the 1 st end electrode finger in the 2 nd direction.

13. An elastic wave device is provided with:

a1 st terminal;

a2 nd terminal having a potential lower than that of the 1 st terminal;

a piezoelectric body; and

a plurality of IDT electrodes provided on the piezoelectric body and electrically connected to the 1 st terminal and the 2 nd terminal,

the plurality of IDT electrodes each have:

1 st bus bar;

a2 nd bus bar opposed to the 1 st bus bar in a1 st direction;

a plurality of 1 st electrode fingers connected to the 1 st bus bar and extending from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction; and

a plurality of 2 nd electrode fingers connected to the 2 nd bus bar and extending from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction,

the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction,

at least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger,

the 1 st bus bar and the 2 nd bus bar each include:

an opening part;

an inner busbar portion located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction;

an outer busbar portion located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction; and

a connecting portion that connects the inner busbar portion and the outer busbar portion in the 1 st direction,

in at least one IDT electrode among the plurality of IDT electrodes, an electrode finger at one end in the 2 nd direction among a group of electrode fingers including the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers is set as a1 st end electrode finger, and an electrode finger at the other end is set as a2 nd end electrode finger, in which case the 1 st end electrode finger is located on the side of an adjacent IDT electrode of the at least one IDT electrode in the 2 nd direction,

in the at least one IDT electrode, an outer bus bar portion of a bus bar not connected to the 1 st end electrode finger among the 1 st bus bar and the 2 nd bus bar is located more inward than an inner bus bar portion of a bus bar not connected to the 1 st end electrode finger among the 1 st bus bar and the 2 nd bus bar, at least on the side of the adjacent IDT electrode in the 2 nd direction.

14. The elastic wave device according to any one of claims 11 to 13,

the plurality of IDT electrodes are arranged in the 2 nd direction,

further provided with: and two reflectors, each provided on the piezoelectric portion on the opposite side of the adjacent IDT electrode, respectively, of the IDT electrodes on both sides among the plurality of IDT electrodes arranged in the 2 nd direction, for reflecting an elastic wave excited by the IDT electrodes.

15. The elastic wave device according to any one of claims 1 to 14,

the distal end portion of at least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes the wide portion.

16. The elastic wave device according to any one of claims 1 to 15,

the elastic wave device has a plurality of regions different from each other in the 1 st direction in a plan view from the thickness direction of the elastic wave device,

the plurality of regions includes:

a central region located at the center in the 1 st direction, the central region including central portions of the 1 st electrode fingers and central portions of the 2 nd electrode fingers;

two outer bus bar regions including the outer bus bar portion of the 1 st bus bar and the outer bus bar portion of the 2 nd bus bar, respectively;

two inner bus bar regions including the inner bus bar portion of the 1 st bus bar and the inner bus bar portion of the 2 nd bus bar, respectively;

two connection regions respectively including a connection portion and an opening portion of the 1 st bus bar and a connection portion and an opening portion of the 2 nd bus bar;

two gap regions respectively including gaps between the plurality of 1 st electrode fingers and the 2 nd bus bar and gaps between the plurality of 2 nd electrode fingers and the 1 st bus bar; and

two wide regions respectively including a wide portion of at least one of the 1 st electrode fingers and a wide portion of at least one of the 2 nd electrode fingers,

in the two outer bus bar regions, the acoustic velocity of an elastic wave becomes slower than that in the central region,

in the two inner bus bar regions, the acoustic velocity of an elastic wave becomes slower than that in the central region,

in the two connection regions, the acoustic velocity of an elastic wave becomes faster than the two outer bus bar regions and the central region,

in the two gap regions, the sound velocity of an elastic wave becomes faster than the two inner bus bar regions and the central region,

in the two wide regions, the acoustic velocity of the elastic wave becomes slower than in the central region.

Technical Field

The present invention relates generally to an acoustic wave device, and more particularly to an acoustic wave device including IDT electrodes.

Background

Conventionally, an acoustic wave device including a piezoelectric substrate (piezoelectric body) and IDT electrodes provided on the piezoelectric substrate, and having wide portions provided at parts of electrode fingers of the IDT electrodes, has been known (for example, see patent document 1). In an example of the acoustic wave device described in patent document 1, reflectors are formed on both sides of an IDT electrode in a surface acoustic wave propagation direction on a piezoelectric substrate. The IDT electrode and the reflectors are formed of a metal material. The acoustic wave device described in patent document 1 is characterized by having a structure in which a piston mode is formed in an IDT electrode, thereby suppressing a transverse mode ripple.

In the acoustic wave device described in patent document 1, the IDT electrode includes: 1 st bus bar; a2 nd bus bar disposed apart from the 1 st bus bar; a plurality of 1 st electrode fingers, the base ends of which are electrically connected to the 1 st bus bar and the tip ends of which extend toward the 2 nd bus bar; and a plurality of No. 2 electrode fingers, the base end of which is connected to the No. 2 bus bar and the front end of which extends toward the No. 1 bus bar. In the elastic wave device described above, the wide portions are provided on both the 1 st electrode finger and the 2 nd electrode finger.

The 1 st bus bar has a plurality of openings arranged apart along the longitudinal direction of the 1 st bus bar. The 1 st bus bar has: an inner bus bar portion located closer to the 1 st electrode finger side than the plurality of openings and extending in the longitudinal direction of the 1 st bus bar; a central busbar portion provided with a plurality of openings; and an outer busbar portion located on the opposite side of the inner busbar portion with the central busbar portion therebetween.

The 2 nd bus bar has a plurality of openings arranged apart along the longitudinal direction of the 2 nd bus bar. The 2 nd bus bar has: an inner bus bar portion located closer to the 2 nd electrode finger side than the plurality of openings and extending in the longitudinal direction of the 2 nd bus bar; a central busbar portion provided with a plurality of openings; and an outer busbar portion located on the opposite side of the inner busbar portion with the central busbar portion therebetween.

Prior art documents

Patent document

Patent document 1: international publication No. 2014/192756

Disclosure of Invention

Problems to be solved by the invention

In an elastic wave device in which a wide portion is provided in a part of the electrode fingers of the IDT electrode, for example, in the end region of the IDT electrode in the longitudinal direction of the 1 st bus bar and the 2 nd bus bar, the outer bus bar portion is adjacent to a metal material portion such as a reflector having a different potential, and therefore, the IDT electrode may be broken by surge due to Electrostatic Discharge (ESD).

An object of the present invention is to provide an acoustic wave device capable of improving ESD resistance while suppressing the obstruction of the piston mode.

Means for solving the problems

An elastic wave device according to an aspect of the present invention includes a1 st terminal, a2 nd terminal, a piezoelectric body, an IDT electrode, and a reflector. The 2 nd terminal has a potential lower than that of the 1 st terminal. The IDT electrode is provided on the piezoelectric body and electrically connected to the 1 st terminal and the 2 nd terminal. The reflector is disposed on the piezoelectric body and electrically connected to the 2 nd terminal. The IDT electrode has a1 st bus bar, a2 nd bus bar, a plurality of 1 st electrode fingers, and a plurality of 2 nd electrode fingers. The 1 st bus bar is electrically connected to the 1 st terminal. The 2 nd bus bar is opposed to the 1 st bus bar in the 1 st direction and is electrically connected to the 2 nd terminal. The plurality of 1 st electrode fingers are connected to the 1 st bus bar and extend from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction. The plurality of 2 nd electrode fingers are connected to the 2 nd bus bar and extend from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction. The 1 st electrode fingers and the 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction. At least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger. The 1 st bus bar and the 2 nd bus bar each include an opening portion, an inner busbar portion, an outer busbar portion, and a connecting portion. The inner busbar portion is located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction. The outer busbar portion is located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction. The connecting portion connects the inner busbar portion and the outer busbar portion in the 1 st direction. In the IDT electrode, an electrode finger located at one end in the 2 nd direction among a group of electrode fingers including the 1 st electrode finger and the 2 nd electrode fingers is set as a1 st end electrode finger, and an electrode finger located at the other end is set as a2 nd end electrode finger, in which case the 1 st end electrode finger is located between the reflector and the 2 nd end electrode finger in the 2 nd direction. An outer bus bar portion of a bus bar not connected to the 1 st terminal electrode finger among the 1 st bus bar and the 2 nd bus bar is located more inward in the 2 nd direction than a central portion of the 1 st terminal electrode finger in the 1 st direction.

An elastic wave device according to an aspect of the present invention includes a1 st terminal, a2 nd terminal, a piezoelectric portion, a plurality of IDT electrodes, and two reflectors. The 2 nd terminal has a potential lower than that of the 1 st terminal. The plurality of IDT electrodes are provided on the piezoelectric body portion and electrically connected to the 1 st terminal and the 2 nd terminal. The two reflectors are provided on the piezoelectric body portion, and reflect elastic waves excited by the plurality of IDT electrodes. The plurality of IDT electrodes each have a1 st bus bar, a2 nd bus bar, a plurality of 1 st electrode fingers, and a plurality of 2 nd electrode fingers. The 2 nd bus bar is opposed to the 1 st bus bar in the 1 st direction. The plurality of 1 st electrode fingers are connected to the 1 st bus bar and extend from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction. The plurality of 2 nd electrode fingers are connected to the 2 nd bus bar and extend from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction. The 1 st electrode fingers and the 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction. At least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger. The 1 st bus bar and the 2 nd bus bar each include an opening portion, an inner busbar portion, an outer busbar portion, and a connecting portion. The inner busbar portion is located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction. The outer busbar portion is located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction. The connecting portion connects the inner busbar portion and the outer busbar portion in the 1 st direction. The plurality of IDT electrodes are arranged in the 2 nd direction. The two reflectors are located on opposite sides of each of IDT electrodes on both sides among the plurality of IDT electrodes arranged in the 2 nd direction from adjacent IDT electrodes. In an IDT electrode adjacent to one of the two IDTs, among the IDT electrodes, an electrode finger located at one end in the 2 nd direction among a group of electrode fingers including the 1 st electrode finger and the 2 nd electrode fingers is set as a1 st end electrode finger, and an electrode finger located at the other end is set as a2 nd end electrode finger, and in this case, the 1 st end electrode finger is located between the one IDT and the 2 nd end electrode finger in the 2 nd direction. In the IDT electrode adjacent to the one reflector, an outer bus bar portion of a bus bar not connected to the 1 st end electrode finger among the 1 st bus bar and the 2 nd bus bar is located more inward in the 2 nd direction than a central portion in the 1 st direction of the 1 st end electrode finger.

An elastic wave device according to an aspect of the present invention includes a1 st terminal, a2 nd terminal, a piezoelectric body, an IDT electrode, and a reflector. The 2 nd terminal has a potential lower than that of the 1 st terminal. The IDT electrode is provided on the piezoelectric body and electrically connected to the 1 st terminal and the 2 nd terminal. The reflector is disposed on the piezoelectric body and electrically connected to the 2 nd terminal. The IDT electrode has a1 st bus bar, a2 nd bus bar, a plurality of 1 st electrode fingers, and a plurality of 2 nd electrode fingers. The 1 st bus bar is electrically connected to the 1 st terminal. The 2 nd bus bar is opposed to the 1 st bus bar in the 1 st direction and is electrically connected to the 2 nd terminal. The plurality of 1 st electrode fingers are connected to the 1 st bus bar and extend from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction. The plurality of 2 nd electrode fingers are connected to the 2 nd bus bar and extend from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction. The 1 st electrode fingers and the 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction. At least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger. The 1 st bus bar and the 2 nd bus bar each include an opening portion, an inner busbar portion, an outer busbar portion, and a connecting portion. The inner busbar portion is located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction. The outer busbar portion is located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction. The connecting portion connects the inner busbar portion and the outer busbar portion in the 1 st direction. In the IDT electrode, an electrode finger located at one end in the 2 nd direction among a group of electrode fingers including the 1 st electrode finger and the 2 nd electrode fingers is set as a1 st end electrode finger, and an electrode finger located at the other end is set as a2 nd end electrode finger, in which case the 1 st end electrode finger is located between the reflector and the 2 nd end electrode finger in the 2 nd direction. An outer bus bar portion of a bus bar not connected to the 1 st terminal electrode finger among the 1 st bus bar and the 2 nd bus bar is located more inside in the 2 nd direction than an inner bus bar portion of a bus bar not connected to the 1 st terminal electrode finger.

An elastic wave device according to an aspect of the present invention includes a1 st terminal, a2 nd terminal, a piezoelectric portion, a plurality of IDT electrodes, and two reflectors. The 2 nd terminal has a potential lower than that of the 1 st terminal. The plurality of IDT electrodes are provided on the piezoelectric body portion and electrically connected to the 1 st terminal and the 2 nd terminal. The two reflectors are provided on the piezoelectric body portion, and reflect elastic waves excited by the plurality of IDT electrodes. The plurality of IDT electrodes each have a1 st bus bar, a2 nd bus bar, a plurality of 1 st electrode fingers, and a plurality of 2 nd electrode fingers. The 2 nd bus bar is opposed to the 1 st bus bar in the 1 st direction. The plurality of 1 st electrode fingers are connected to the 1 st bus bar and extend from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction. The plurality of 2 nd electrode fingers are connected to the 2 nd bus bar and extend from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction. The 1 st electrode fingers and the 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction. At least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger. The 1 st bus bar and the 2 nd bus bar each include an opening portion, an inner busbar portion, an outer busbar portion, and a connecting portion. The inner busbar portion is located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction. The outer busbar portion is located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction. The connecting portion connects the inner busbar portion and the outer busbar portion in the 1 st direction. The plurality of IDT electrodes are arranged in the 2 nd direction. The two reflectors are located on opposite sides of each of IDT electrodes on both sides among the plurality of IDT electrodes arranged in the 2 nd direction from adjacent IDT electrodes. In an IDT electrode adjacent to one of the two IDTs, among the IDT electrodes, an electrode finger located at one end in the 2 nd direction among a group of electrode fingers including the 1 st electrode finger and the 2 nd electrode fingers is set as a1 st end electrode finger, and an electrode finger located at the other end is set as a2 nd end electrode finger, and in this case, the 1 st end electrode finger is located between the one IDT and the 2 nd end electrode finger in the 2 nd direction. In the IDT electrode adjacent to the one reflector, an outer bus bar portion of a bus bar not connected to the 1 st end electrode finger among the 1 st bus bar and the 2 nd bus bar is located more inward in the 2 nd direction than an inner bus bar portion of a bus bar not connected to the 1 st end electrode finger.

An elastic wave device according to an aspect of the present invention includes a1 st terminal, a2 nd terminal, a piezoelectric portion, and a plurality of IDT electrodes. The 2 nd terminal has a potential lower than that of the 1 st terminal. The plurality of IDT electrodes are provided on the piezoelectric body portion and electrically connected to the 1 st terminal and the 2 nd terminal. The plurality of IDT electrodes each have a1 st bus bar, a2 nd bus bar, a plurality of 1 st electrode fingers, and a plurality of 2 nd electrode fingers. The 2 nd bus bar is opposed to the 1 st bus bar in the 1 st direction. The plurality of 1 st electrode fingers are connected to the 1 st bus bar and extend from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction. The plurality of 2 nd electrode fingers are connected to the 2 nd bus bar and extend from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction. The 1 st electrode fingers and the 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction. At least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger. The 1 st bus bar and the 2 nd bus bar each include an opening portion, an inner busbar portion, an outer busbar portion, and a connecting portion. The inner busbar portion is located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction. The outer busbar portion is located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction. The connecting portion connects the inner busbar portion and the outer busbar portion in the 1 st direction. When one of two IDT electrodes adjacent to each other in the 2 nd direction among the plurality of IDT electrodes is a1 st IDT electrode and the other is a2 nd IDT electrode, the interval between the outer busbar portion not connected to the electrode finger closest to the 2 nd IDT electrode among a set of electrode fingers including the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers among the 1 st IDT electrodes and the outer busbar portion not connected to the electrode finger closest to the 1 st IDT electrode among the set of electrode fingers including the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers among the 2 nd IDT electrodes is larger than the interval between the center portion of the electrode finger closest to the 2 nd IDT electrode among the 1 st IDT electrodes and the center portion of the electrode finger closest to the 1 st IDT electrode among the 2 nd IDT electrodes.

An elastic wave device according to an aspect of the present invention includes a1 st terminal, a2 nd terminal, a piezoelectric portion, and a plurality of IDT electrodes. The 2 nd terminal has a potential lower than that of the 1 st terminal. The plurality of IDT electrodes are provided on the piezoelectric body portion and electrically connected to the 1 st terminal and the 2 nd terminal. The plurality of IDT electrodes each have a1 st bus bar, a2 nd bus bar portion, a plurality of 1 st electrode fingers, and a plurality of 2 nd electrode fingers. The 2 nd bus bar is opposed to the 1 st bus bar in the 1 st direction. The plurality of 1 st electrode fingers are connected to the 1 st bus bar and extend from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction. The plurality of 2 nd electrode fingers are connected to the 2 nd bus bar and extend from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction. The 1 st electrode fingers and the 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction. At least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger. The 1 st busbar and the 2 nd busbar each include an opening portion, an inner busbar portion, an outer busbar portion, and a connecting portion. The inner busbar portion is located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction. The outer busbar portion is located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction. The connecting portion connects the inner busbar portion and the outer busbar portion in the 1 st direction. When one of two IDT electrodes adjacent in the 2 nd direction among the plurality of IDT electrodes is set as a1 st IDT electrode and the other is set as a2 nd IDT electrode, an electrode finger at an end located on the 2 nd IDT electrode side in the 2 nd direction among a group of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers including the 1 st IDT electrode is set as a1 st end electrode finger of the 1 st IDT electrode, an electrode finger at an end located on the opposite side to the 2 nd IDT electrode is set as a2 nd end electrode finger of the 1 st IDT electrode, an electrode finger at an end located on the 1 st IDT electrode side in the 2 nd direction among the plurality of 1 st electrode fingers and the group of the plurality of 2 nd electrode fingers including the 2 nd IDT electrode is set as a1 st end electrode finger of the 2 nd IDT electrode, an electrode finger at an end located on the opposite side to the 1 st IDT electrode is set as a2 nd electrode finger of the 2 nd IDT electrode, in this case, the 1 st end electrode finger of the 1 st IDT electrode is connected to the 1 st terminal, and the 1 st end electrode finger of the 2 nd IDT electrode is connected to the 2 nd terminal. In each of the 1 st IDT electrode and the 2 nd IDT electrode, an outer bus bar portion electrically connected to a terminal other than the 1 st end electrode finger among the 1 st terminal and the 2 nd terminal is located more inward than the inner bus bar portion electrically connected to a terminal other than the 1 st end electrode finger in the 2 nd direction.

An elastic wave device according to an aspect of the present invention includes a1 st terminal, a2 nd terminal, a piezoelectric portion, and a plurality of IDT electrodes. The 2 nd terminal has a potential lower than that of the 1 st terminal. The plurality of IDT electrodes are provided on the piezoelectric body portion and electrically connected to the 1 st terminal and the 2 nd terminal. The plurality of IDT electrodes each have a1 st bus bar, a2 nd bus bar portion, a plurality of 1 st electrode fingers, and a plurality of 2 nd electrode fingers. The 2 nd bus bar is opposed to the 1 st bus bar in the 1 st direction. The plurality of 1 st electrode fingers are connected to the 1 st bus bar and extend from the 1 st bus bar to the 2 nd bus bar side in the 1 st direction. The plurality of 2 nd electrode fingers are connected to the 2 nd bus bar and extend from the 2 nd bus bar to the 1 st bus bar side in the 1 st direction. The 1 st electrode fingers and the 2 nd electrode fingers are arranged to be spaced apart from each other in a2 nd direction orthogonal to the 1 st direction. At least one of the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers includes a wide portion having a width in the 2 nd direction larger than a central portion in the 1 st direction of the at least one electrode finger. The 1 st bus bar and the 2 nd bus bar each include an opening portion, an inner busbar portion, an outer busbar portion, and a connecting portion. The inner busbar portion is located closer to the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers than the opening portion in the 1 st direction. The outer busbar portion is located on the opposite side of the opening portion from the inner busbar portion in the 1 st direction. The connecting portion connects the inner busbar portion and the outer busbar portion in the 1 st direction. In at least one IDT electrode among the plurality of IDT electrodes, an electrode finger located at one end in the 2 nd direction among a group of electrode fingers including the plurality of 1 st electrode fingers and the plurality of 2 nd electrode fingers is set as a1 st electrode finger, and an electrode finger located at the other end is set as a2 nd electrode finger, in which case the 1 st electrode finger is located on the side of an adjacent IDT electrode of the at least one IDT electrode in the 2 nd direction. In the at least one IDT electrode, an outer bus bar portion of a bus bar not connected to the 1 st end electrode finger among the 1 st bus bar and the 2 nd bus bar is located more inward than an inner bus bar portion of a bus bar not connected to the 1 st end electrode finger among the 1 st bus bar and the 2 nd bus bar, at least on the side of the adjacent IDT electrode in the 2 nd direction.

Effects of the invention

The invention provides an elastic wave device capable of improving ESD resistance while suppressing obstruction of a piston mode.

Drawings

Fig. 1 is a plan view of an elastic wave device according to embodiment 1 of the present invention.

Fig. 2A is a plan view of a part of an elastic wave device according to embodiment 1 of the present invention. Fig. 2B relates to the elastic wave device as described above, and is a sectional view taken along line a-a of fig. 2A.

Fig. 3 is an enlarged view of a main part of the elastic wave device as above.

Fig. 4 is a schematic explanatory view of a velocity distribution in the 1 st direction of the sound velocity of an elastic wave propagating in the elastic wave propagation direction (2 nd direction) in the elastic wave device as above.

Fig. 5 is an explanatory view of charge distribution of the elastic wave device as described above.

Fig. 6 is an enlarged view of a main portion of an elastic wave device according to modification 1 of embodiment 1 of the present invention.

Fig. 7 is a plan view of an elastic wave device according to embodiment 2 of the present invention.

Fig. 8 is a plan view of a part of an elastic wave device according to embodiment 2 of the present invention.

Fig. 9 relates to the elastic wave device as described above, and is a sectional view taken along line a-a of fig. 8.

Fig. 10 is an enlarged view of a main portion of the elastic wave device as above.

Fig. 11 is an explanatory diagram of the charge distribution of the elastic wave device as described above.

Fig. 12 is an enlarged view of a main portion of an elastic wave device according to modification 1 of embodiment 2 of the present invention.

Fig. 13 is a plan view of a part of an elastic wave device according to modification 2 of embodiment 2 of the present invention.

Fig. 14 is an enlarged view of a main portion of the elastic wave device as above.

Fig. 15 is an enlarged view of a main portion of an elastic wave device according to modification 3 of embodiment 2 of the present invention.

Fig. 16 is a cross-sectional view of an elastic wave device according to modification 4 of embodiment 2 of the present invention.

Fig. 17 is a cross-sectional view of an elastic wave device according to modification 5 of embodiment 2 of the present invention.

Detailed Description

Hereinafter, the elastic wave devices according to embodiments 1 and 2 will be described with reference to the drawings.

Fig. 1 to 17 referred to in embodiments 1 and 2 and the like below are schematic diagrams, and the ratio of the size and thickness of each component in the diagrams does not necessarily reflect the actual dimensional ratio.

(embodiment mode 1)

(1.1) integral Structure of elastic wave device

Hereinafter, an elastic wave device 1 according to embodiment 1 will be described with reference to the drawings.

As shown in fig. 1, 2A, 2B, 3, and 4, elastic wave device 1 according to embodiment 1 includes a1 st terminal (e.g., signal terminal) 11, a2 nd terminal (e.g., ground terminal) 12, a piezoelectric portion 24, an IDT (interdigital transducer) electrode 3, and a reflector 8. The 2 nd terminal 12 has a potential lower than that of the 1 st terminal 11. Therefore, the 1 st terminal 11 has a potential higher than that of the 2 nd terminal 12. The 1 st terminal 11 and the 2 nd terminal 12 are provided on the piezoelectric body 24. Here, the term "provided on the piezoelectric body 24" includes a case where the piezoelectric body 24 is directly provided and a case where the piezoelectric body 24 is indirectly provided. The acoustic wave device 1 includes a plurality of (three) 2 nd terminals 12, but may include at least one. The piezoelectric body 24 is formed of a piezoelectric material. The IDT electrode 3 and the reflector 8 are provided on the piezoelectric body 24. Here, the term "provided on the piezoelectric body 24" includes a case where the piezoelectric body 24 is directly provided and a case where the piezoelectric body 24 is indirectly provided. The acoustic wave device 1 according to embodiment 1 is a single-port type surface acoustic wave resonator. The elastic wave device 1 includes two reflectors 8.

Further, elastic wave device 1 according to embodiment 1 further includes: a1 st wiring layer 13 electrically connecting the IDT electrode 3 and the 1 st terminal 11; and a2 nd wiring layer 14 electrically connecting the IDT electrode 3 and the 2 nd terminal 12. In fig. 1, for convenience of explanation, the 1 st terminal 11 and the IDT electrode 3 are marked with a mark "H" at a portion (high potential side portion) electrically connected to the 1 st terminal 11, and the 2 nd terminal 12 and the IDT electrode 3 are marked with a mark "E" at a portion (low potential side portion) electrically connected to the 2 nd terminal 12. The high-potential side portion and the low-potential side portion are different in potential. The high-potential side portion is a portion that is higher in potential than the low-potential side portion. The reference numerals of "H" and "E" are not reference numerals and do not actually exist. In fig. 1 and 2A, although the IDT electrode 3 and the reflectors 8 are dotted hatching, the hatching does not show a cross section but is merely marked for easy understanding of the relationship between the IDT electrode 3 and the reflectors 8 and the piezoelectric section 24. Note that, in fig. 1, the 1 st terminal 11, the 2 nd terminal 12, the 1 st wiring layer 13, and the 2 nd wiring layer 14 are dotted hatching, but these hatching do not show a cross section, but are merely marked for easy understanding of the relationship between the 1 st terminal 11, the 2 nd terminal 12, the 1 st wiring layer 13, and the 2 nd wiring layer 14 and the piezoelectric section 24.

In acoustic wave device 1 according to embodiment 1, piezoelectric portion 24 is a piezoelectric film, and IDT electrode 3 is formed on laminated substrate 2 having piezoelectric portion 24. The laminated substrate 2 is a piezoelectric substrate having piezoelectricity at least in part.

(1.2) Components of elastic wave device

Next, each constituent element of elastic wave device 1 will be described with reference to the drawings.

(1.2.1) laminated substrate

As shown in fig. 2B, the laminated substrate 2 includes: a high sound velocity support substrate 21; a low acoustic velocity film 23 directly laminated on the high acoustic velocity support substrate 21, the acoustic velocity of the Bulk wave (Bulk wave) propagating at a lower velocity than the acoustic velocity of the elastic wave propagating through the piezoelectric body 24; and a piezoelectric body 24 directly laminated on the low sound velocity membrane 23. In the high acoustic velocity support substrate 21, the acoustic velocity of the propagated bulk wave is higher than the acoustic velocity of the elastic wave propagated through the piezoelectric body 24. The low acoustic velocity film 23 is provided on the high acoustic velocity support substrate 21. Here, the term "provided on the low sound velocity membrane 23" includes a case of being directly provided on the low sound velocity membrane 23 and a case of being indirectly provided on the low sound velocity membrane 23. The piezoelectric body 24 is indirectly laminated on the high acoustic velocity support substrate 21. In this case, in the acoustic wave device 1, the low acoustic velocity film 23 is formed between the high acoustic velocity support substrate 21 and the piezoelectric body portion 24, and thus the acoustic velocity of the acoustic wave is reduced. Elastic waves are essentially energy-concentrated in a medium with low acoustic velocity. Therefore, in the acoustic wave device 1, the effect of limiting the acoustic wave energy into the piezoelectric body 24 and the IDT electrode 3 that excites the acoustic wave can be improved. Therefore, in elastic wave device 1, the loss can be reduced and the Q value can be increased, as compared with the case where low acoustic velocity film 23 is not provided.

The piezoelectric body 24 is made of, for example, lithium tantalate (LiTaO)₃) Lithium niobate (LiNbO)₃) Zinc oxide (ZnO), aluminum nitride (AlN), or lead zirconate titanate (PZT).

The high acoustic velocity support substrate 21 supports a laminate including a low acoustic velocity film 23 and a piezoelectric body portion 24. The high acoustic speed support substrate 21 has a1 st main surface 211 and a2 nd main surface 212 on opposite sides to each other in the thickness direction thereof. The 1 st major surface 211 and the 2 nd major surface 212 face away from each other. The shape of the high-speed support substrate 21 in plan view (the outer peripheral shape of the high-speed support substrate 21 when viewed in the thickness direction) is a square shape, but is not limited to a square shape, and may be a rectangular shape, for example. The thickness of the high-sound-velocity support substrate 21 is, for example, 120 μm. The material of the high sound velocity support substrate 21 is silicon. The high acoustic velocity support substrate 21 is not limited to silicon, and may be formed of, for example, a piezoelectric such as aluminum nitride, alumina, silicon carbide, silicon nitride, sapphire, lithium tantalate, lithium niobate, quartz, alumina, zirconia, cordierite, mullite, steatite, forsterite, or other ceramics, a magnesia diamond (magnesia diamond), or a material containing the above materials as a main component, or a material containing a mixture of the above materials as a main component.

The low acoustic velocity film 23 is made of silicon oxide, glass, silicon oxynitride, tantalum oxide, a compound in which fluorine, carbon, or boron is added to silicon oxide, or any of materials mainly containing the above materials.

In the case where the low sound velocity membrane 23 is silicon oxide, the temperature characteristics can be improved. Lithium tantalate has a negative temperature characteristic in the elastic constant, and silicon oxide has a positive temperature characteristic. Therefore, in elastic wave device 1, the absolute value of the Temperature Coefficient of Frequency (TCF) can be reduced. Moreover, the inherent acoustic impedance of silicon oxide is less than the inherent acoustic impedance of lithium tantalate. Therefore, in elastic wave device 1, both the increase of the electromechanical coupling coefficient, that is, the amplification of the relative frequency band, and the improvement of the frequency-temperature characteristic can be achieved.

When λ is the wavelength of the elastic wave defined by the electrode finger period of the IDT electrode 3, the thickness of the piezoelectric body 24 is preferably 3.5 λ or less. This is because the Q value becomes high. In elastic wave device 1, the frequency-temperature characteristic is improved by setting the thickness of piezoelectric body 24 to 2.5 λ or less. Further, in the acoustic wave device 1, the thickness of the piezoelectric body 24 is set to 1.5 λ or less, thereby facilitating the adjustment of the sound velocity. The thickness of the piezoelectric body 24 is, for example, 600 nm.

When the wavelength of the elastic wave defined by the electrode finger period of the IDT electrode 3 is λ, the thickness of the low acoustic velocity film 23 is preferably 2.0 λ or less. In the acoustic wave device 1, the film stress can be reduced by setting the thickness of the low acoustic velocity film 23 to 2.0 λ or less, and as a result, the warpage of the wafer serving as the base of the high acoustic velocity support substrate 21 can be reduced during manufacturing, and the improvement of the yield and the stabilization of the characteristics can be achieved. The thickness of the low acoustic velocity film 23 is, for example, 600 nm.

(1.2.2) Reflector

Two reflectors 8 are arranged on one main face 241 of the piezoelectric body 24. Here, two reflectors 8 are disposed one on each side of the IDT electrode 3 in the 2 nd direction D2.

The two reflectors 8 each reflect elastic waves. The two reflectors 8 are each a grid reflector. The two reflectors 8 each have a plurality of electrode fingers 9, and one ends of the plurality of electrode fingers 9 in the 1 st direction D1 are short-circuited to each other and the other ends are short-circuited to each other. In fig. 1, 2A, 2B, and the like, each of the two reflectors 8 is depicted with a reduced number of electrode fingers 9 for easy viewing of the drawings. Each reflector 8 can be formed of an appropriate metal material such as aluminum (Al), copper (Cu), platinum (Pt), gold (Au), silver (Ag), titanium (Ti), nickel (Ni), chromium (Cr), molybdenum (Mo), tungsten (W), or an alloy mainly composed of any of these metals. Each reflector 8 may have a structure in which a plurality of metal films made of these metals or alloys are laminated. The thickness of each reflector 8 is, for example, 150 nm.

(1.2.3) IDT electrode

The IDT electrode 3 can be formed of an appropriate metal material such as aluminum, copper, platinum, gold, silver, titanium, nickel, chromium, molybdenum, tungsten, or an alloy mainly composed of any of these metals. The IDT electrode 3 may have a structure in which a plurality of metal films made of these metals or alloys are laminated. The thickness of the IDT electrode 3 is, for example, 150 nm.

As shown in fig. 1 and 2A, the IDT electrode 3 includes a1 st bus bar 4, a2 nd bus bar 5, a plurality of 1 st electrode fingers 6, and a plurality of 2 nd electrode fingers 7.

In the IDT electrode 3, the 1 st bus bar 4 and the 2 nd bus bar 5 face each other in the 1 st direction D1 orthogonal to the thickness direction (vertical direction in fig. 2B) of the piezoelectric section 24. That is, the 2 nd bus bar 5 is opposed to the 1 st bus bar 4 in the 1 st direction D1.

The 1 st bus bar 4 and the 2 nd bus bar 5 are elongated in the longitudinal direction of the 2 nd direction D2 perpendicular to the 1 st direction D1. Although the 1 st bus bar 4 and the 2 nd bus bar 5 are not seen to be long in fig. 1, 2A, 4, and the like, the number of the 1 st electrode finger 6 and the 2 nd electrode finger 7 is reduced for easy viewing of the drawings. The 2 nd direction D2 is a direction along the propagation direction of the elastic wave. The 2 nd direction D2 is also orthogonal to the thickness direction of the piezoelectric body 24.

The 1 st electrode fingers 6 are connected to the 1 st bus bar 4 and extend from the 1 st bus bar 4 toward the 2 nd bus bar 5 in the 1 st direction D1. Here, the plurality of 1 st electrode fingers 6 extend from the 1 st bus bar 4 in a direction orthogonal to the longitudinal direction of the 1 st bus bar 4. That is, the plurality of 1 st electrode fingers 6 extend in a direction orthogonal to the propagation direction of the elastic wave. In the IDT electrode 3, the 1 st electrode finger 6 and the 2 nd bus bar 5 are separated from each other, and a gap 31 is formed between the 1 st electrode finger 6 and the 2 nd bus bar 5 facing each other in the 1 st direction D1. When the wavelength of the elastic wave is λ, the length of the gap 31 in the 1 st direction D1 is, for example, 0.5 λ or less.

In the example of fig. 1 and 2A, the plurality of 1 st electrode fingers 6 have the same length. The distal end portions 61 of the 1 st electrode fingers 6 include wide portions 62 having a width in the 2 nd direction D2 greater than the width of the central portions 60 of the 1 st electrode fingers 6 in the 1 st direction D1. Each of the plurality of 1 st electrode fingers 6 includes a wide portion 64 different from the wide portion 62 (see fig. 2A). The wide portion 64 is formed between the base end portion 63 (see fig. 2A) of the 1 st electrode finger 6 opposite to the tip end portion 61 and the central portion 60, and has a width in the 2 nd direction D2 greater than that of the central portion 60 of the 1 st electrode finger 6 in the 1 st direction D1. The wide width part 64 is separated from the 1 st bus bar 4 in the 1 st direction D1. In each of the plurality of 1 st electrode fingers 6, a portion between the wide width portion 62 and the wide width portion 64 in the 1 st direction D1 constitutes the central portion 60. In each of the plurality of 1 st electrode fingers 6, the central portion 60 is longer than the wide portions 62, 64 in the 1 st direction D1.

In the example of fig. 1 and 2A, the center portions 60 of the plurality of 1 st electrode fingers 6 have the same width. The width of the wide portion 62 of the tip portion 61 of each of the plurality of 1 st electrode fingers 6 is the same. The width of the wide portions 64 on the base end portion 63 side of each of the plurality of 1 st electrode fingers 6 is the same. The width of the wide portion 62 of the distal end portion 61 of each of the plurality of 1 st electrode fingers 6 is equal to the width of the wide portion 64 on the proximal end portion 63 side. Each of the 1 st electrode fingers 6 has a line-symmetrical shape with respect to a center line 6X (see fig. 3) along the 1 st direction D1. The wide portions 62 and 64 are rectangular in shape, but are not limited thereto, and may be hexagonal in shape, circular in shape, and the like.

The plurality of 2 nd electrode fingers 7 are connected to the 2 nd bus bar 5, and extend from the 2 nd bus bar 5 toward the 1 st bus bar 4 side in the 1 st direction D1. Here, the plurality of 2 nd electrode fingers 7 extend from the 2 nd bus bar 5 in a direction orthogonal to the longitudinal direction of the 2 nd bus bar 5. That is, the plurality of 2 nd electrode fingers 7 extend in a direction orthogonal to the propagation direction of the elastic wave. In the IDT electrode 3, the plurality of 2 nd electrode fingers 7 are separated from the 1 st bus bar 4, and a gap 32 is formed between the 2 nd electrode finger 7 and the 1 st bus bar 4 facing each other in the 1 st direction D1. When the wavelength of the elastic wave is λ, the length of the gap 32 in the 1 st direction D1 is, for example, 0.5 λ or less.

In the example of fig. 1 and 2A, the plurality of 2 nd electrode fingers 7 have the same length. The distal end portions 71 of the plurality of 2 nd electrode fingers 7 include wide portions 72 having a width in the 2 nd direction D2 greater than the width of the central portion 70 of the 2 nd electrode finger 7 in the 1 st direction D1. Each of the plurality of 2 nd electrode fingers 7 includes a wide portion 74 (see fig. 2A) different from the wide portion 72. The wide portion 74 is formed between the base end portion 73 (see fig. 2A) of the 2 nd electrode finger 7 opposite to the tip end portion 71 and the central portion 70, and has a width in the 2 nd direction D2 larger than the width of the central portion 70 in the 1 st direction D1 of the 2 nd electrode finger 7. The wide part 74 is separated from the 2 nd bus bar 5 in the 1 st direction D1. In each of the plurality of 2 nd electrode fingers 7, a portion between the wide width portion 72 and the wide width portion 74 in the 1 st direction D1 constitutes the central portion 70. In each of the plurality of 2 nd electrode fingers 7, the central portion 70 is longer than the wide portions 72 and 74 in the 1 st direction D1.

In the example of fig. 1 and 2A, the center portions 70 of the plurality of 2 nd electrode fingers 7 have the same width. The width of the wide portion 72 of the tip portion 71 of each of the plurality of 2 nd electrode fingers 7 is the same. The width of the wide portions 74 on the base end portions 73 side of the plurality of 2 nd electrode fingers 7 is the same. The width of the wide portion 72 of the distal end portion 71 of each of the plurality of 2 nd electrode fingers 7 is equal to the width of the wide portion 74 on the proximal end portion 73 side. Each of the plurality of 2 nd electrode fingers 7 has a line-symmetrical shape with respect to a center line 7X (see fig. 3) along the 1 st direction D1. The wide portions 72 and 74 are rectangular in shape, but are not limited thereto, and may be hexagonal in shape, circular in shape, and the like.

In the IDT electrode 3, a plurality of 1 st electrode fingers 6 and a plurality of 2 nd electrode fingers 7 are alternately arranged in a spaced manner in a2 nd direction D2 orthogonal to the 1 st direction D1. Therefore, the 1 st electrode finger 6 and the 2 nd electrode finger 7 adjacent in the 2 nd direction D2 are separated.

In the IDT electrode 3, the wide portions 62 of the tip portions 61 of the 1 st electrode finger 6 and the wide portions 74 on the base end portion 73 side of the 2 nd electrode finger 7 are alternately arranged in a spaced manner in the 2 nd direction D2. In the IDT electrode 3, the wide portions 64 on the base end 63 side of the 1 st electrode finger 6 and the wide portions 72 on the tip end 71 of the 2 nd electrode finger 7 are alternately arranged in the 2 nd direction D2 so as to be spaced apart from each other. The electrode finger period of the IDT electrode 3 is a value 2 times the distance between the corresponding sides of the center portion 60 of the 1 st electrode finger 6 and the center portion 70 of the 2 nd electrode finger 7 adjacent to each other. The electrode finger period of the IDT electrode 3 is the same value even if it is defined by the distance between the center lines 6X (see fig. 3) of two 1 st electrode fingers 6 adjacent to each other in the 2 nd direction D2 among the plurality of 1 st electrode fingers 6. The electrode finger period of the IDT electrode 3 is defined by the distance between the center lines 7X (see fig. 3) of two adjacent 2 nd electrode fingers 7 in the 2 nd direction D2 among the plurality of 2 nd electrode fingers 7, and has the same value. The electrode fingers of one set may be arranged so that the plurality of 1 st electrode fingers 6 and the plurality of 2 nd electrode fingers 7 are spaced apart from each other in the 2 nd direction D2 perpendicular to the 1 st direction D1, or the plurality of 1 st electrode fingers 6 and the plurality of 2 nd electrode fingers 7 may be arranged so as not to be alternately spaced apart from each other. For example, a region in which the 1 st electrode finger 6 and the 2 nd electrode finger 7 are arranged separately one by one, and a region in which the 1 st electrode finger 6 or the 2 nd electrode finger 7 are arranged in the 2 nd direction D2 may exist at the same time.

The 1 st busbar 4 includes an opening 40, an inner busbar portion 42, an outer busbar portion 41, and a connecting portion 43. The inner busbar portions 42 are positioned closer to the plurality of 1 st electrode fingers 6 and the plurality of 2 nd electrode fingers 7 than the openings 40 in the 1 st direction D1. The outer busbar portion 41 is located on the opposite side of the opening portion 40 from the inner busbar portion 42 in the 1 st direction D1. That is, the outer busbar portion 41 is located on the opposite side of the 1 st electrode finger 6 in the 1 st direction D1. The connecting portion 43 connects the inner busbar portion 42 and the outer busbar portion 41 in the 1 st direction D1. The connection portion 43 is located on both sides of the opening 40 in the 2 nd direction D2. In the example of fig. 1, the connecting portion 43 has the same width as the central portion 60 of the 1 st electrode finger 6, and is located on the extension line of the 1 st electrode finger 6. However, the size of the coupling portion 43 and the arrangement of the coupling portion 43 are not limited to these.

The opening shape of the opening 40 is rectangular, but the invention is not limited thereto. When the wavelength of the elastic wave is λ, the width of the inner busbar portion 42 in the 1 st direction D1 is, for example, 0.5 λ or less. The length of the coupling portion 43 in the 1 st direction D1 is, for example, 2.0 λ.

The 1 st bus bar 4 includes a plurality of openings 40, for example, but fig. 1 and 2A illustrate the number of the 1 st electrode fingers 6 to be reduced for easy view of the drawings, and therefore only one opening 40 is illustrated in fig. 1 and 2A. The plurality of openings 40 are arranged at substantially equal intervals in the 2 nd direction D2, for example. In the example of fig. 1 and 2A, the opening width of the opening 40 in the 2 nd direction D2 is, for example, the same as the distance between the central portions 60 of the two 1 st electrode fingers 6 adjacent to each other in the 2 nd direction D2. As described above, although only one opening 40 is shown in fig. 1 and 2A, the distance between two openings 40 adjacent to each other in the 2 nd direction D2 is, for example, the same as the width of the center portion 60 of the 1 st electrode finger 6 in the 2 nd direction D2.

The 2 nd busbar 5 includes an opening 50, an inner busbar portion 52, an outer busbar portion 51, and a connecting portion 53. The inner busbar portion 52 is positioned closer to the plurality of 1 st electrode fingers 6 and the plurality of 2 nd electrode fingers 7 than the opening portion 50 in the 1 st direction D1. The outer busbar portion 51 is located on the opposite side of the opening portion 50 from the inner busbar portion 52 in the 1 st direction D1. That is, the outer busbar portion 51 is located on the opposite side of the 1 st direction D1 from the side where the plurality of 2 nd electrode fingers 7 are present. The connecting portion 53 connects the inner busbar portion 52 and the outer busbar portion 51 in the 1 st direction D1. The connection portion 53 is located on both sides of the opening 50 in the 2 nd direction D2. In the example of fig. 1 and 2A, the connection portion 53 has the same width as the central portion 70 of the 2 nd electrode finger 7, and is located on the extension line of the 2 nd electrode finger 7. However, the size of the coupling portion 53 and the arrangement of the coupling portion 53 are not limited to these.

The opening shape of the opening 50 is rectangular, but is not limited thereto. When the wavelength of the elastic wave is λ, the width of the inner busbar portion 52 in the 1 st direction D1 is, for example, 0.5 λ or less. The length of the connection portion 53 in the 1 st direction D1 is, for example, 2.0 λ.