| 摘要 |
PURPOSE:To obtain a high-precision surface acoustic wave device easily by vapor-depositing a thin film with an asymmetric lattice array on a substrate which transmits a surface acoustic wave to a specific film thickness by sputtering, etc., and preferably irradiating it with light. CONSTITUTION:The thin film having the asymmetric array with regard to variance in the center frequency f0 of a surface acoustic wave filter is vapor-deposited on a propagation path of the surface acoustic wave by sputtering while cooled to, for example, room temperature, and then the f0 is adjusted only by varying the vapor-deposition time. For the purpose, the thin film having the asymmetric lattice array of SiO2 is formed by sputtering on the propagation path of the surface acoustic wave on the crystal substrate. A curve 21 shows negative-to-positive variation in f0 wuth sputtering time, and this variation is utilized to adjust the film thickness to <=10Angstrom by the sputtering time. In this case, when the film thickness is <=10Angstrom because the sputtering time is too short, the vapor-deposited film is not continuous and the reproducibility of characteristics is not obtained. When the film thickness is >=0.03, the insertion loss increases above 1dB as shown by a curve 22 and its practicability is not obtained. |
