Surface acoustic wave device
View Patent ↗A surface acoustic wave device has a piezoelectric substrate and an IDT formed on the piezoelectric substrate, and uses an excited wave as an SH wave. The piezoelectric substrate is a quartz plate in which a cut angle θ of a rotated Y-cut quartz substrate is set in the range of −65°≦θ≦−51° in a counter-clockwise direction from a crystal Z-axis and the propagation direction of a surface acoustic wave is set in the range (90°±5°) with respect to a crystal X-axis. The IDT is made of Ta or an alloyed metal containing Ta as the main component.
1. A surface acoustic wave device having a piezoelectric substrate and an IDT formed on the piezoelectric substrate and using an excited wave as an SH wave,
wherein the piezoelectric substrate is a rotation Y-cut substrate made from a quartz flat substrate, where a cut angle θ of the piezoelectric substrate is a rotation angle of a crystal Z-axis when the piezoelectric substrate is rotated around a crystal X-axis, a direction in which the piezoelectric substrate is rotated from a positive Z-axis side to a positive Y-axis side is a direction in which the cut angle θ is negative, and the cut angle θ is set in the range of −65°≦θ≦−61°, and a propagation direction of a surface acoustic wave is set in the range (90°±5°) with respect to the crystal X-axis, and
the IDT is made of Ta or an alloyed metal containing Ta as the main component.
2. A surface acoustic wave device having a piezoelectric substrate and an IDT formed on the piezoelectric substrate and using an excited wave as an SH wave,
wherein the piezoelectric substrate is a rotation Y-cut substrate made from a quartz flat substrate, where a cut angle θ of the piezoelectric substrate is a rotation angle of a crystal Z-axis when the piezoelectric substrate is rotated around a crystal X-axis, a direction in which the piezoelectric substrate is rotated from a positive Z-axis side to a positive Y-axis side is a direction in which the cut angle θ is negative, and the cut angle θ is set in the range of −65°≦θ≦−51°, and a propagation direction of a surface acoustic wave is set in the range (90°±5°) with respect to the crystal X-axis, and an electrode thickness H/λ, standardized by a wavelength of the IDT, is set in the range of 0.01≦H/λ≦0.05 when a wavelength of an excited surface acoustic wave is set to be λ, and
the IDT is made of Ta or an alloyed metal containing Ta as the main component,
wherein a multiplication H/λ·mr of the electrode thickness H/λ and a metallization ratio mr is set in the range of 0.004≦H/λ·mr≦0.019, the metallization ratio mr of the electrode fingers of the IDT being represented by (electrode finger widths)/(electrode finger widths+spaces between electrode fingers), and
wherein when the metallization ratio mr is set in the range of 0.004≦H/λ·mr <0.019, the cut angle θ at which a turnover temperature is maintained substantially at room temperature decreases as the electrode thickness H/λ increases or the metallization ratio mr increases.
3. The surface acoustic wave device according to claim 1 ,
wherein a multiplication H/λ·mr of an electrode thickness H/λ and a metallization ratio mr is set in the range of 0.004≦H/λ·mr<0.019, when the metallization ratio mr of the electrode fingers of the IDT is represented by (electrode finger widths)/(electrode finger widths+spaces between electrode fingers).
4. A complex device using the surface acoustic wave device described in claim 1 and including an oscillation circuit or a module device.
5. A complex device using the surface acoustic wave device described in claim 2 and including an oscillation circuit or a module device.
6. A surface acoustic wave device having a piezoelectric substrate and an IDT formed on the piezoelectric substrate, the surface acoustic wave device using an SH wave as an excitation wave, the surface acoustic wave device comprising:
grating reflectors on both sides of the IDT that reflect a surface acoustic wave,
wherein the piezoelectric substrate is a rotation Y-cut substrate made from a quartz flat substrate, where a cut angle θ of the piezoelectric substrate is a rotation angle of a crystal Z-axis when the piezoelectric substrate is rotated around a crystal X-axis, a direction in which the piezoelectric substrate is rotated from a positive Z-axis side to a positive Y-axis side is a direction in which the cut angle θ is negative, and the cut angle θ is set in the range of −65°≦θ≦−51°, and a propagation direction of the surface acoustic wave is set in the range (90°±5°) with respect to the crystal X-axis, and an electrode thickness H/λ, standardized by a wavelength of the IDT, is set in the range of 0.01≦H/λ≦0.05 when a wavelength of an excited surface acoustic wave is set to be λ,
wherein a multiplication H/λ·mr of the electrode thickness H/λ and a metallization ratio mr is set in the range of 0.004≦H/λ·mr<0.019, the metallization ratio mr of the electrode fingers of the IDT being represented by (electrode finger widths)/(electrode finger widths+spaces between electrode fingers), and
wherein when the metalization ratio mr is set in the range of 0.004≦H/λ·mr <0.019, the cut angle θ at which a turnover temperature is maintained substantially at room temperature decreases as the electrode thickness H/λ increases or the metallization ratio mr increases, and
the IDT is made of Ta or an alloyed metal containing Ta as the main component.
7. A complex device using the surface acoustic wave device described in claim 6 and including an oscillation circuit or a module device.