Elastic wave device

1. An elastic wave device comprising:

a support substrate;

a multilayer film provided on the support substrate and including a piezoelectric thin film;

an interdigital transducer electrode provided on a surface of the piezoelectric thin film;

an electrode pad electrically connected to the interdigital transducer electrode; and

a first insulating layer provided on the support substrate in a region outside the multilayer film in a plan view in a direction of thickness of the support substrate, and located below the electrode pad.

2. The elastic wave device according to claim 1 , wherein the first insulating layer is made of a resin.

3. The elastic wave device according to claim 1 , wherein the support substrate is made of a conductor or a semiconductor, and the first insulating layer is located below an external connection terminal that is connected to the electrode pad.

4. The elastic wave device according to claim 3 , wherein the first insulating layer is made of a resin.

5. The elastic wave device according to claim 1 , further comprising:

a wiring electrode connected to the interdigital transducer electrode; wherein

the electrode pad is connected to the interdigital transducer electrode via the wiring electrode; and

an external connection terminal is connected to the electrode pad.

6. The elastic wave device according to claim 1 , wherein the first insulating layer includes an insulating layer extension portion extending from the region outside the multilayer film, to a region where the multilayer film is provided.

7. The elastic wave device according to claim 6 , wherein the insulating layer extension portion covers a portion of the piezoelectric thin film.

8. The elastic wave device according to claim 5 , wherein the wiring electrode extends from the upper surface of the multilayer film via a side surface of the multilayer film to the electrode pad.

9. The elastic wave device according to claim 8 , wherein the side surface on which the wiring electrode of the multilayer film is provided is an inclined surface inclined from a direction perpendicular or substantially perpendicular to an upper surface of the support substrate, and the inclined surface is closer to the interdigital transducer electrode side as the inclined surface extends from below toward above.

10. The elastic wave device according to claim 9 , wherein the inclined surface of the multilayer film includes a step.

11. The elastic wave device according to claim 9 , wherein the first insulating layer covers at least a portion of the inclined surface.

12. The elastic wave device according to claim 1 , wherein

a plurality of interdigital transducer electrodes are provided as the interdigital transducer electrode provided on the surface of the piezoelectric thin film; and

the elastic wave device further comprises a connection wire connecting the adjacent interdigital transducer electrodes to each other.

13. The elastic wave device according to claim 12 , wherein portions of the layers of the multilayer film is provided between the connection wire and the support substrate.

14. The elastic wave device according to claim 13 , wherein a second insulating layer is provided between the support substrate and the connection wire and is made of a same material as that of the first insulating layer.

15. The elastic wave device according to claim 1 , wherein a third insulating layer is further provided between the multilayer film and the support substrate.

16. The elastic wave device according to claim 15 , wherein the first insulating layer is provided on the third insulating layer and provided between a side surface of the multilayer film and the electrode pad.

17. The elastic wave device according to claim 1 , wherein the first insulating layer extends from a height position located below the electrode pad via a side surface of the multilayer film to an upper surface of the multilayer film, and an outer surface of the first insulating layer on a side surface of the multilayer film is an inclined surface that is inclined from a direction perpendicular or substantially perpendicular to an upper surface of the support substrate and is closer to the interdigital transducer electrode side as the inclined surface extends from below toward above.

18. The elastic wave device according to claim 1 , wherein

the multilayer film includes, as other layers, a high-acoustic-velocity film through which a bulk wave propagates at an acoustic velocity higher than that of an elastic wave that propagates through the piezoelectric thin film, and a low-acoustic-velocity film on the high-acoustic-velocity film and through which a bulk wave propagates at an acoustic velocity lower than that of a bulk wave that propagates through the piezoelectric thin film; and

the piezoelectric thin film is provided on the low-acoustic-velocity film.

19. The elastic wave device according to claim 1 , further comprising a low-acoustic-velocity film provided on a lower surface of the piezoelectric thin film and through which a transversal wave propagates at a relatively low acoustic velocity; wherein

the support substrate is a high-acoustic-velocity support substrate laminated on a lower surface of the low-acoustic-velocity film and through which a transversal wave propagates at a relatively high acoustic velocity compared to the relatively low acoustic velocity.

20. The elastic wave device according to claim 1 , further comprising an external connection terminal connected to the electrode pad and including a metal bump.

21. The elastic wave device according to claim 1 , further comprising:

a frame-shaped support member surrounds a region where the interdigital transducer electrode is provided; and

a lid member fixed on the support member so as to close an opening in the frame-shaped support member.

22. The elastic wave device according to claim 21 , further comprising an external connection terminal connected to the electrode pad and including an under bump metal layer and a metal bump joined to the under bump metal layer.

23. The elastic wave device according to claim 1 , further comprising:

a wiring electrode connected to the interdigital transducer electrode and the electrode pad; and

an external connection terminal electrically connected to the electrode pad and located above the electrode pad.