Acoustic wave device, filter, and multiplexer
An acoustic wave device includes: a Y-cut X-propagation lithium tantalate substrate having a cut angle of 5° or greater and 18° or less; and a grating electrode that is formed of one or more metal films stacked on the lithium tantalate substrate, a number of the one or more metal films being n (n is a natural number), excites an acoustic wave, and meets a condition: 0.16 λ ≤ ∑ i = 1 n ( hi × ρ i ρ 0 ) ≤ 0.24 λ where ρi represents a density of each metal film of the one or more metal films, hi represents a film thickness of the each metal film, ρ 0 represents a density of Mo, and λ represents a pitch.
1. An acoustic wave device comprising:
a Y-cut X-propagation lithium tantalate substrate having a cut angle of 5° or greater and 19° or less; and
a grating electrode that is formed of one or more metal films stacked on the lithium tantalate substrate, a number of the one or more metal films being n (n is a natural number), excites an acoustic wave, and meets a condition:
0.16
λ
≤
∑
i
=
1
n
(
hi
×
ρ
i
ρ
0
)
≤
0.24
λ
where ρi represents a density of each metal film of the one or more metal films, hi represents a film thickness of the each metal film, ρ 0 represents a density of Mo, and λrepresents a pitch.
2. The acoustic wave device according to claim 1 , wherein
the cut angle is 5.5° or greater and 7.5° or less, and
the grating electrode meets a condition:
0.22
λ
≤
∑
i
=
1
n
(
hi
×
ρ
i
ρ
0
)
≤
0.24
λ
.
3. The acoustic wave device according to claim 1 , wherein
the cut angle is 7.5° or greater and 10.5° or less, and
the grating electrode meets a condition:
0.20
λ
≤
∑
i
=
1
n
(
hi
×
ρ
i
ρ
0
)
≤
0.24
λ
.
4. The acoustic wave device according to claim 1 , wherein
the cut angle is 10.5° or greater and 12° or less, and
the grating electrode meets a condition:
0.18
λ
≤
∑
i
=
1
n
(
hi
×
ρ
i
ρ
0
)
≤
0.24
λ
.
5. The acoustic wave device according to claim 1 , wherein
the cut angle is 12° or greater and 14° or less, and
the grating electrode meets a condition:
0.17
λ
≤
∑
i
=
1
n
(
hi
×
ρ
i
ρ
0
)
≤
0.24
λ
.
6. The acoustic wave device according to claim 1 , wherein
the cut angle is 14° or greater and 16° or less, and
the grating electrode meets a condition:
0.16
λ
≤
∑
i
=
1
n
(
hi
×
ρ
i
ρ
0
)
≤
0.20
λ
.
7. The acoustic wave device according to claim 1 , wherein
the cut angle is 16° or greater and 19° or less, and
the grating electrode meets a condition:
0.16
λ
≤
∑
i
=
1
n
(
hi
×
ρ
i
ρ
0
)
≤
0.17
λ
.
8. The acoustic wave device according to claim 1 , wherein
a primary mode of the acoustic wave is an SH-type oscillation mode, and
an acoustic velocity of the acoustic wave is lower than an acoustic velocity of Rayleigh mode spurious.
9. The acoustic wave device according to claim 2 , wherein
the one or more metal films include a metal film mainly composed of at least one of Cu, W, Ru, Mo, Ta, Pt, Pd, Ir, Rh, Re, and Te.
10. An acoustic wave device comprising:
a Y-cut X-propagation lithium tantalate substrate having a cut angle of 5° or greater and 18° or less, and
a grating electrode that is located on the lithium tantalate substrate, and excites an acoustic wave, a primary mode of the acoustic wave being an SH-type oscillation mode, an acoustic velocity of the acoustic wave being lower than an acoustic velocity of Rayleigh mode spurious.
11. A filter comprising
the acoustic wave device according to claim 1 .
12. A multiplexer comprising
the filter according to claim 11 .
13. A filter comprising
the acoustic wave device according to claim 10 .
14. A multiplexer comprising
the filter according to claim 13 .