Elastic wave device and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-10601394-B2
Application number	US-201715430887-A
Country	US
Kind code	B2
Filing date	Feb 13, 2017
Priority date	Oct 20, 2014
Publication date	Mar 24, 2020
Grant date	Mar 24, 2020

Abstract

An elastic wave device includes interdigital transducer electrodes on a piezoelectric substrate and wires electrically connected to the interdigital transducer electrodes. The wires include a first wire and a second wire. The device further includes an interlayer insulating film made from an inorganic dielectric material and covering a portion of the first wire. A portion of the second wire bridges a portion of the first wire with the interlayer insulating film provided therebetween. In a region, in a bridged area, where the second wire extends from a region on an outer side portion of the interlayer insulating film to above the interlayer insulating film, first auxiliary wire electrodes are provided on the piezoelectric substrate, such that when viewed in plan view, the first auxiliary wire electrodes at least partially overlap with the second wire and extend to within the interlayer insulating film.

First claim

What is claimed is:

1. An elastic wave device comprising:
a piezoelectric substrate;
a plurality of interdigital transducer electrodes provided on the piezoelectric substrate; and
a plurality of wires provided on the piezoelectric substrate and electrically connected to the plurality of interdigital transducer electrodes; wherein
the plurality of wires includes a first wire and a second wire connected to a different potential from the first wire;
the device further comprises an interlayer insulating film made from an inorganic dielectric material and provided on the piezoelectric substrate to cover a portion of the first wire;
a portion of the second wire bridges a portion of the first wire with the interlayer insulating film provided therebetween to define a bridged area;
the device further comprises a first auxiliary wire electrode, extending from a region on an outer side portion of the interlayer insulating film to a region where the interlayer insulating film is provided at the bridged area, being laminated to a lower surface of the second wire at the region on the outer side portion of the interlayer insulating film, and being located below the interlayer insulating film and the second wire at the region where the interlayer insulating film is provided at the bridged area;
the interlayer insulating film includes first and second side surfaces located on one side and another side of the first wire, the first side surface and the second side surface are sloping surfaces that slope toward a center area of the interlayer insulating film as the side surfaces progress upward, and in the region on the outer side portion of the interlayer insulating film, a border surface between the first auxiliary wire electrode and the second wire slopes upward as the border surface nears the interlayer insulating film; and
a slope angle of the first and second side surfaces of the interlayer insulating film relative to an upper surface of the piezoelectric substrate is greater than a slope angle of the border surface between the first auxiliary wire electrode and the second wire relative to the upper surface of the piezoelectric substrate.

2. The elastic wave device according to claim 1 , wherein the first auxiliary wire electrode is provided on both one side and another side of the first wire at the bridged area.

3. The elastic wave device according to claim 1 , wherein a surface roughness at an area of the first auxiliary wire electrode where the second wire is laminated is higher than a surface roughness at an area of the first auxiliary wire electrode covered by the interlayer insulating film.

4. The elastic wave device according to claim 3 , wherein an area of the first auxiliary wire electrode that makes contact with the second wire is an Al alloy layer containing Cu, and includes a protrusion made from a CuAl 2 intermetallic compound.

5. The elastic wave device according to claim 1 , further comprising a second auxiliary wire electrode extending in a direction in which the first wire extends, laminated to the first wire in a region on an outer side portion of the interlayer insulating film, extending to the top of the interlayer insulating film, and separated from the second wire.

6. The elastic wave device according to claim 1 , wherein the slope angle of the first and second side surfaces of the interlayer insulating film is no greater than about 50°.

7. The elastic wave device according to claim 1 , wherein the first and second side surfaces of the interlayer insulating film include a lower side surface portion in which the slope angle is relatively great and an upper side surface portion in which the slope angle is relatively small.

8. The elastic wave device according to claim 1 , wherein the interlayer insulating film includes a first dielectric material layer made from a first inorganic dielectric material and a second dielectric material layer laminated on the first dielectric material layer.

9. The elastic wave device according to claim 7 , wherein the interlayer insulating film includes a first dielectric material layer made from a first inorganic dielectric material and a second dielectric material layer made from a second inorganic dielectric material that is different from the first inorganic dielectric material, a side surface of the first dielectric material layer defining the lower side surface portion and a side surface of the second dielectric material layer defining the upper side surface portion.

10. The elastic wave device according to claim 1 , further comprising:
a support member provided on the piezoelectric substrate and surrounding the interdigital transducer electrodes such that a hollow area facing the interdigital transducer electrodes is defined; and
a cover provided on the support member and sealing the hollow area.

11. The elastic wave device according to claim 10 , wherein the support member extends to above at least one of the bridged areas.

Assignees

• Murata Manufacturing Co

Inventors

• Kikuchi Taku
• Michigami Akira
• Sekiya Daisuke
• Tsubokawa Masashi

Classifications

• H03H3/08

  for the manufacture of resonators or networks using surface acoustic waves · CPC title

• H03H9/145 Primary

  for networks using surface acoustic waves · CPC title

• H03H9/1071

  the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the SAW device · CPC title

• H03H9/6433

  Coupled resonator filters · CPC title

• H03H9/1092

  the enclosure being defined by a cover cap mounted on an element forming part of the surface acoustic wave [SAW] device on the side of the IDT's · CPC title