| 摘要 |
PROBLEM TO BE SOLVED: To enable high-frequency operation and to obtain a good conforming article rate by the use of existing photolithography technique by specifying cut surfaces of lithium niobate single crystal and lithium tantalate single crystal. SOLUTION: For lithium niobate, an X-cut substrate of single crystal is so set that 95<=Ψ<=120 and 0.07<=h/λ<=0.09, whereΨis the angle between the direction of an inter-digital electrode and a Y-axis from the Y-axis to a Z-axis, and h/λis the ratio of the electrode film width (h) and propagation wavelengthλof the inter-digital electrode, formed on a surface having a normal matching the X-axis of the single crystal. In this case, a propagation speed of 6,000 to 6,500m/s is obtained with a surface acoustic wave in propagation mode, different from the propagation mode of a convention surface acoustic wave. The pitch for the electrode fingers is only set to the wavelength, and the width L of the electrode fingers is set to 1/4 of the wavelength, so that the width of the electrode fingers becomes >=0.5μm at a high frequency of, for example, 2.4GHz. Then the existing photolithography technique can be used.
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