Acoustic wave device and method of manufacturing the same
An acoustic wave device includes: a piezoelectric substrate; an IDT that is formed on the piezoelectric substrate and includes a pair of comb-shaped electrodes facing each other, each of the pair of comb-shaped electrodes including an grating electrode that excites an acoustic wave and a bus bar to which the grating electrode is connected; and reforming regions that are located only inside the piezoelectric substrate and arranged at intervals under the IDT, and in which a material of the piezoelectric substrate is reformed.
1. An acoustic wave device comprising:
a single piezoelectric substrate;
an IDT that is formed on the single piezoelectric substrate and includes a pair of comb-shaped electrodes facing each other, each of the pair of comb-shaped electrodes including a grating electrode that excites an acoustic wave and a bus bar to which the grating electrode is connected; and
reforming regions that are located only inside the single piezoelectric substrate and arranged at intervals each other under the IDT, and in which a material of the single piezoelectric substrate is reformed,
wherein the reforming regions have an amorphous structure.
2. The acoustic wave device according to claim 1 , wherein
the reforming regions are dotted in the single piezoelectric substrate immediately under the IDT.
3. The acoustic wave device according to claim 2 , wherein
the reforming regions are located along a line in a direction different from a cleavage direction of the single piezoelectric substrate.
4. The acoustic wave device according to claim 2 , wherein
the reforming regions are located along a line in a different direction from a cleavage direction of the single piezoelectric substrate, and forms a first reforming region group and a second reforming region group located in a direction intersecting the different direction, and
the reforming regions of the first reforming region group is located so as not to overlap with the reforming regions of the second reforming region group as viewed from the direction intersecting the different direction.
5. The acoustic wave device according to claim 2 , wherein
the reforming regions are located at two or more different depths in the single piezoelectric substrate.
6. The acoustic wave device according to claim 2 , wherein
the single piezoelectric substrate is a rotated Y-cut X-propagation lithium tantalate substrate or a rotated Y-cut X-propagation lithium niobate substrate, and
the reforming regions are located along a line in an X-axis direction of a crystal orientation of the single piezoelectric substrate.
7. The acoustic wave device according to claim 1 , further comprising:
a support substrate of which an upper surface is bonded on a lower surface of the single piezoelectric substrate.
8. The acoustic wave device according to claim 7 , wherein
the reforming regions are dotted in the single piezoelectric substrate immediately under the IDT,
the single piezoelectric substrate has a linear expansion coefficient in a first direction greater than a linear expansion coefficient in a second direction intersecting the first direction,
the support substrate has linear expansion coefficients in the first direction and the second direction approximately equal to each other, and
the reforming regions are located along a line in the first direction.
9. The acoustic wave device according to claim 8 , wherein
the single piezoelectric substrate is a rotated Y-cut X-propagation lithium tantalate substrate or a rotated Y-cut X-propagation lithium niobate substrate,
the support substrate is a sapphire substrate or a spinel substrate, and
the first direction is an X-axis direction of a crystal orientation of the piezoelectric substrate.
10. The acoustic device according to claim 1 , wherein
the reforming regions are located approximately at a same depth in the single piezoelectric substrate, and
an interval between the reforming regions in a plane direction of a surface of the single piezoelectric substrate on which the IDT is formed is less than a wavelength of a bulk wave propagating through an inside of the single piezoelectric substrate.
11. The acoustic wave device according to claim 1 , wherein
the reforming regions are located along a straight line in a propagation direction of the acoustic wave, forms a first reforming region group and a second reforming region group located side by side as viewed from a direction perpendicular to a surface of the single piezoelectric substrate on which the IDT is formed, and are not located between the first reforming region group and the second reforming region group.
12. The acoustic wave device according to claim 10 , wherein
the reforming regions are located near a center of the IDT in a direction intersecting the propagation direction of the acoustic wave.
13. The acoustic wave device according to claim 1 , wherein
the reforming regions are located along a straight line in a direction intersecting a propagation direction of the acoustic wave, forms a first reforming region group and a second reforming region group located side by side as viewed from a direction perpendicular to a surface of the single piezoelectric substrate on which the IDT is formed, and are not located between the first reforming region group and the second reforming region group.
14. The acoustic wave device according to claim 1 , wherein
the reforming regions are located along a straight line in a direction orthogonal to a propagation direction of the acoustic wave, forms a first reforming region group and a second reforming region group located side by side as viewed from a direction perpendicular to a surface of the single piezoelectric substrate on which the IDT is formed, and are not located between the first reforming region group and the second reforming region group.