Acoustic wave device, wafer, and method of manufacturing wafer

Patent metadata

Field	Value
Publication number	US-12149228-B2
Application number	US-202217991259-A
Country	US
Kind code	B2
Filing date	Nov 21, 2022
Priority date	Dec 27, 2021
Publication date	Nov 19, 2024
Grant date	Nov 19, 2024

Abstract

An acoustic wave device includes a support substrate, a piezoelectric layer provided on the support substrate, at least a pair of comb-shaped electrodes provided on the piezoelectric layer, each of the comb-shaped electrodes including a plurality of electrode fingers, and an insulating layer provided between the support substrate and the piezoelectric layer, the insulating layer having, in at least a part thereof, a plurality of void regions of which extending directions are different from each other when viewed from a thickness direction of the support substrate, a width in the corresponding extending direction of each of the void regions being longer than a width in a direction orthogonal to the corresponding extending direction when viewed from the thickness direction of the support substrate.

First claim

What is claimed is:

1. An acoustic wave device comprising:
a support substrate;
a piezoelectric layer provided on the support substrate;
at least a pair of comb-shaped electrodes provided on the piezoelectric layer, each of the comb-shaped electrodes including a plurality of electrode fingers; and
an insulating layer provided between the support substrate and the piezoelectric layer, the insulating layer having, in at least a part thereof, a plurality of void regions of which extending directions are different from each other when viewed from a thickness direction of the support substrate, a width in the corresponding extending direction of each of the void regions being longer than a width in a direction orthogonal to the corresponding extending direction when viewed from the thickness direction of the support substrate.

2. The acoustic wave device according to claim 1 , wherein the plurality of void regions of which the extending directions different from each other are connected to each other to form one void region.

3. The acoustic wave device according to claim 2 , wherein the one void region has a shape in which a void region extends in a plurality of directions from one point when viewed from the thickness direction of the support substrate.

4. The acoustic wave device according to claim 2 , wherein the one void region has a shape provided so as to surround a part of the insulating layer when viewed from the thickness direction of the support substrate.

5. The acoustic wave device according to claim 1 , wherein an area of the plurality of void regions in a cross-sectional view is equal to or greater than 1% of an area of the insulating layer including the plurality of void regions.

6. The acoustic wave device according to claim 1 , wherein an interface between the support substrate and the insulating layer is an uneven surface.

7. The acoustic wave device according to claim 6 , wherein the plurality of void regions overlap a recess portion of the uneven surface.

8. The acoustic wave device according to claim 1 , wherein in a cross-sectional shape of each of the plurality of void regions, a width at a side of the piezoelectric layer is narrower than a width at a side of the support substrate.

9. The acoustic wave device according to claim 1 , wherein a distance between each of the plurality of void regions and the piezoelectric layer is equal to or greater than an average pitch of the plurality of electrode fingers.

10. The acoustic wave device according to claim 1 , wherein the insulating layer includes a first insulating layer and a second insulating layer, the first insulating layer is provided on the support substrate, has the plurality of void regions, and is penetrated by the plurality of void regions, and the second insulating layer is provided on the first insulating layer and has no void region.

11. The acoustic wave device according to claim 10 , further comprising a third insulating layer provided on the second insulating layer, the third insulating layer having an acoustic velocity lower than those of the first insulating layer and the second insulating layer.

12. A wafer comprising:
a support substrate;
a piezoelectric layer provided on the support substrate;
an insulating layer provided between the support substrate and the piezoelectric layer, the insulating layer having, in at least a part thereof, a plurality of void regions of which extending directions are different from each other when viewed from a thickness direction of the support substrate, a width in the corresponding extending direction of each of the plurality of void regions being longer than a width in a direction orthogonal to the corresponding extending direction.

13. A method of manufacturing a wafer, the method comprising:
forming, on a support substrate having an uneven surface, an insulating layer having a plurality of first void regions that are in contact with a recess portion of the uneven surface;
forming a plurality of second void regions in the insulating layer by etching parts in contact with the plurality of first void regions of the insulating layer, extending directions of the plurality of second void regions being different from each other when viewed from a thickness direction of the support substrate, a width in the corresponding extending direction of each of the plurality of second void regions being longer than a width in a direction orthogonal to the corresponding extending direction when viewed from the thickness direction of the support substrate; and
forming a piezoelectric layer on the insulating layer.

Assignees

• Taiyo Yuden Kk

Inventors

• Yamamoto Shinji
• Sato Koichi
• Nakazato Toshiharu

Classifications

• H10N30/073

  by fusion of metals or by adhesives · CPC title

• H03H9/6483

  Ladder SAW filters · CPC title

• H03H9/14541

  Multilayer finger or busbar electrode · CPC title

• H03H9/725

  Duplexers · CPC title

• H03H9/02559

  of lithium niobate or lithium-tantalate substrates · CPC title