| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a SAW element, which enables formation of a microscopic electrode pattern of the IDT in its interior, and can cope with increase in turning into high frequency. SOLUTION: A resist pattern 12 is formed on the surface of a wafer 9 formed with an electrode region 10, which is made to coat with an aluminium thin film to pattern the thin film and comprises an IDT, in such a way that a resist material is applied on the surface of the wafer 9 and parts, which are used as interdigital electrodes, of the wafer 9 are left and thereafter, the exposed aluminium thin film on the region 10 is anodically oxidated to oxidize the thin film and the IDT is formed. In another embodiment, after the exposed thin film is removed to its middle by a dry etching, the remaining thin film is completely oxidized by the anodic oxidation treatment to form the IDT. In this SAW element, the interdigital electrodes 3a and 3b adjoining each other are separated from each other through each Al2O3 thin film 7. The IDT can be coated with a flat insulating film 8, having a piezoelectricity and in that case, a non-piezoelectric material, which is high in the propagation velocity of a surface acoustic wave, can be used for a substrate.
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