Acoustic wave device, filter, and multiplexer
An acoustic wave device includes: a piezoelectric substrate bonded on a support substrate, a surface including protruding portions and/or recessed portions being interposed between the piezoelectric substrate and the support substrate; a first acoustic wave resonator that includes first electrode fingers with a first average pitch and is disposed on the piezoelectric substrate in a first region where an average interval between the protruding portions and/or the recessed portions in a direction in which the first electrode fingers are arranged is a first interval; and a second acoustic wave resonator that includes second electrode fingers with a second average pitch different from the first average pitch, and is disposed on the piezoelectric substrate in a second region where an average interval between the protruding portions and/or the recessed portions in a direction in which the second electrode fingers are arranged is a second interval different from the first interval.
1. An acoustic wave device comprising:
a support substrate;
a piezoelectric substrate directly or indirectly bonded on the support substrate, a surface including protruding portions and/or recessed portions being interposed between the piezoelectric substrate and the support substrate;
a first acoustic wave resonator including first electrode fingers, an average pitch of the first electrode fingers being a first pitch, the first acoustic wave resonator being disposed on the piezoelectric substrate in a first region where an average interval between the protruding portions and/or the recessed portions in a direction in which the first electrode fingers are arranged is a first interval, the protruding portions and/or recessed portions being regularly arranged at first constant intervals in the first region, each of the first constant intervals between the protruding portions and/or between the recessed portions being substantially uniform; and
a second acoustic wave resonator including second electrode fingers, an average pitch of the second electrode fingers being a second pitch; the second pitch being different from the first pitch, the second acoustic wave resonator being disposed on the piezoelectric substrate in a second region where an average interval between the protruding portions and/or the recessed portions in a direction in which the second electrode fingers are arranged is a second interval, the protruding portions and/or recessed portions being regularly arranged at second constant intervals in the second region, each of the second constant intervals between the protruding portions and/or between the recessed portions being substantially uniform, the second interval being different from the first interval.
2. The acoustic wave device according to claim 1 ; wherein
the first pitch is less than the second pitch, and the first interval is less than the second interval.
3. The acoustic wave device according to claim 1 , wherein
the first interval is equal to or greater than 1.2 times the first pitch and equal to or less than 2.8 times the first pitch, and
the second interval is equal to or greater than 1.2 times the second pitch and equal to or less than 2.8 times the second pitch.
4. The acoustic wave device according to claim 1 , wherein
heights of the protruding portions and/or depths of the recessed portions in the first region are equal to or greater than 0.2 times the first pitch, and
heights of the protruding portions and/or depths of the recessed portions in the second region are equal to or greater than 0.2 times the second pitch.
5. The acoustic wave device according to claim 1 , further comprising:
an insulating layer between the support substrate and the piezoelectric substrate, wherein
the surface is an interface between the support substrate and the insulating layer.
6. The acoustic wave device according to claim 5 , wherein
a temperature coefficient of an elastic constant of the insulating layer is opposite in sign to a temperature coefficient of an elastic constant of the piezoelectric substrate.
7. The acoustic wave device according to claim 5 , wherein
an average distance between a surface, on which the first electrode fingers are disposed, of the piezoelectric substrate and the surface in the first region is less than four times the first pitch, and an average distance between a surface, on which the second electrode fingers are disposed, of the piezoelectric substrate and the surface in the second region is less than four times the second pitch.
8. A filter comprising:
the acoustic wave device according to claim 1 .
9. A filter comprising:
the acoustic wave device according to claim 2 ,
wherein the first acoustic wave resonator is a series resonator connected in series between a first terminal and a second terminal, and
the second acoustic wave resonator is a parallel resonator connected in parallel between the first terminal and the second terminal.
10. A multiplexer comprising:
the filter according to claim 8 .
11. A multiplexer comprising:
the filter according to claim 9 .