Acoustic wave device, high frequency front end circuit, communication apparatus, and manufacturing method for acoustic wave device

1. An end surface reflection acoustic wave device in which acoustic waves are reflected between a first end surface and a second end surface opposing each other, the acoustic wave device comprising:

a piezoelectric body including the first end surface and the second end surface, and a first principal surface and a second principal surface opposing each other and connecting the first end surface and the second end surface;

a first electrode finger provided on the first principal surface of the piezoelectric body and extending in a second direction, where a direction in which the first end surface and the second end surface are connected is defined as a first direction and a direction orthogonal or substantially orthogonal to the first direction on the first principal surface is defined as the second direction; and

a second electrode finger provided on the first principal surface of the piezoelectric body, arranged separately from the first electrode finger with a gap interposed between the first electrode finger and the second electrode finger, and extending in the second direction on the first principal surface of the piezoelectric body; wherein

a portion in which the first electrode finger and the second electrode finger overlap with each other when viewed from the first direction is defined as an intersecting portion, a distance between the first end surface and the second end surface of the piezoelectric body is defined as a width of the piezoelectric body, and the piezoelectric body is provided with a different width portion having a width different from a width of the piezoelectric body at a central portion of the intersecting portion in the second direction in a region where the first end surface and the second end surface oppose each other.

2. The acoustic wave device according to claim 1 , wherein

the different width portion includes a thin width portion; and

the thin width portion has a smaller width than the width of the piezoelectric body at the central portion.

3. The acoustic wave device according to claim 2 , wherein the thin width portion is provided in at least one of a first outer side portion and a second outer side portion of the intersecting portion in the second direction.

4. The acoustic wave device according to claim 2 , further comprising:

recessed portions opposing each other in the first direction at both of the first end surface and the second end surface of the piezoelectric body and including the thin width portion.

5. The acoustic wave device according to claim 1 , wherein

the different width portion includes a thick width portion; and

the thick width portion is larger in width than the width of the piezoelectric body at the central portion.

6. The acoustic wave device according to claim 5 , wherein within the intersecting portion, the thick width portion is provided at each of a first end side and a second end side of the intersecting portion in the second direction.

7. The acoustic wave device according to claim 1 , wherein

in the second direction, the first electrode finger is extended to a first outer side portion of the intersecting portion, and the second electrode finger is extended to a second outer side portion of the intersecting portion; and

a first busbar and a second busbar are respectively connected to the first electrode finger and the second electrode finger and extend in a direction intersecting with the second direction.

8. The acoustic wave device according to claim 7 , wherein

the different width portion includes a first thin width portion and a second thin width portion;

the first thin width portion has a width smaller than the width of the piezoelectric body at the central portion, and is disposed in the first outer side portion of the intersecting portion and at an inner side of the first busbar in the second direction; and

the second thin width portion has a width smaller than the width of the piezoelectric body at the central portion, and is disposed in the second outer side portion of the intersecting portion and at an inner side of the second busbar in the second direction.

9. The acoustic wave device according to claim 1 , wherein the different width portion tapers in the second direction toward an outer side or an inner side.

10. The acoustic wave device according to claim 1 , wherein a plurality of at least one of the first electrode finger and the second electrode finger are provided.

11. The acoustic wave device according to claim 1 , wherein

the piezoelectric body is a piezoelectric film;

the acoustic wave device further comprises a support member including a support surface supporting the piezoelectric film and including a recessed portion on the support surface; and

the piezoelectric film is fixed to the support member such that at least the intersecting portion of the piezoelectric film is located on or above the recessed portion with respect to the support member.

12. The acoustic wave device according to claim 1 , further comprising:

a support member that supports the piezoelectric body; wherein

the support member includes a high acoustic velocity material layer in which a bulk wave propagates at a higher acoustic velocity than an acoustic velocity of an acoustic wave propagating in the piezoelectric body.

13. The acoustic wave device according to claim 12 , wherein the support member includes a low acoustic velocity material layer which is provided closer to a side of the piezoelectric body than the high acoustic velocity material layer, and in which a bulk wave propagates at a lower acoustic velocity than the acoustic velocity of an acoustic wave propagating in the piezoelectric body.

14. The acoustic wave device according to claim 12 , wherein the support member is a high acoustic velocity substrate made of the high acoustic velocity material layer.

15. The acoustic wave device according to claim 12 , wherein

the piezoelectric body includes a vibration body portion having a rectangular or substantially rectangular shape, a first anchor portion connected to one end of the vibration body portion, and a second anchor portion connected to another end of the vibration body; and

both of the first anchor portion and the second anchor portion are connected to different portions of the support member.

16. The acoustic wave device according to claim 1 , further comprising:

a support member that supports the piezoelectric body; wherein

the support member includes a low acoustic impedance layer having a relatively low acoustic impedance; and

a high acoustic impedance layer having a relatively high acoustic impedance.

17. A manufacturing method of the acoustic wave device according to claim 1 , the method comprising:

processing the piezoelectric body to provide the different width portion in which a width of the piezoelectric body is partially different; and

providing the first and second electrode fingers on the first principal surface of the piezoelectric body.

18. The acoustic wave device according to claim 1 , wherein a plurality of the first electrode fingers and a plurality of the second electrode fingers are provided.

19. A high frequency front end circuit comprising:

the acoustic wave device according to claim 1 ; and

a power amplifier.

20. A communication apparatus comprising:

the high frequency front end circuit according to claim 19 ; and

a radio frequency signal processing circuit.