| 摘要 |
PROBLEM TO BE SOLVED: To provide a SAW device using a quartz substrate, which reduces a capacitance ratioγand improves frequency controllability. SOLUTION: A piezoelectric substrate 1 is a quartz flat plate in which a cutting angle of rotation Y cut quartz flat plate is set to a range of -61.4°<θ<-51.1°in a counter-clock-wise direction from a crystal Z axis and a propagation direction of surface acoustic waves is set to 90°±5°with respect to a crystal X axis, surface acoustic waves to be excited being SH waves. Furthermore, an IDT 2 and grating reflectors 3a, 3b are comprised of Al or an alloy with Al as a main component, and an electrode film thickness H which is standardized with a wavelengthλof surface acoustic waves is set to 0.04<H/λ<0.12. Then, when a line occupancy ratio of electrode fingers constituting the IDT is defined as electrode finger width/(electrode finger width + space between electrode fingers), the line occupancy ratio mr is set to 0.53≤mr≤0.65, or 0.55≤mr≤0.68. COPYRIGHT: (C)2008,JPO&INPIT
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