Surface acoustic wave device and duplexer
View Patent ↗A surface acoustic wave device includes a supporting substrate, a LiTaO3 piezoelectric substrate joined on the supporting substrate, which has a normal line direction on a main surface thereof in a direction rotated 43° to 53° from a Y axis to a Z axis direction about an X axis, and an electrode pattern formed on the piezoelectric substrate.
1. A surface acoustic wave device comprising:
a supporting substrate;
a LiTaO3 piezoelectric substrate joined directly on the supporting substrate, which has a normal line direction on a main surface thereof in a direction rotated 43° to 53° from a Y axis to a Z axis direction about an X axis; and
an electrode pattern formed on the piezoelectric substrate,
wherein the piezoelectric substrate is attached on the supporting substrate comprising a sapphire substrate,
wherein the joined interface between the supporting substrate and the piezoelectric substrate has a smoothness that restrains bulk waves reflected by the joined interface from being scattered.
2. The surface acoustic wave device as claimed in claim 1 , wherein the normal line direction on the main surface is in the direction rotated 43° to 53° from the Y axis to the Z axis direction about the X axis.
3. The surface acoustic wave device as claimed in claim 1 , wherein the normal line direction on the main surface is in the direction rotated 46° to 50° from the Y axis to the Z axis direction about the X axis.
4. The surface acoustic wave device as claimed in claim 1 , wherein an amorphous joining region is interposed between the supporting substrate and the piezoelectric substrate.
5. The surface acoustic wave device as claimed in claim 1 , wherein the surface acoustic wave device is a filter including a resonator having the electrode pattern.
6. A duplexer comprising:
a common terminal; and
a first filter and a second filter connected to the common terminal, at least one of the first and second filters including:
a supporting substrate;
a LiTaO3 piezoelectric substrate joined directly on the supporting substrate, which has a normal line direction on a main surface thereof in a direction rotated 43° to 53° from a Y axis to a Z axis direction about an X axis; and
an electrode pattern formed on the piezoelectric substrate,
wherein the piezoelectric substrate is attached on the supporting substrate comprising a sapphire substrate,
wherein the joined interface between the supporting substrate and the piezoelectric substrate has a smoothness that restrains bulk waves reflected by the joined interface from being scattered.