| 摘要 |
PROBLEM TO BE SOLVED: To attain fine adjustment to a desired center frequency when an exciting electrode is formed and to secure high productivity of a surface acoustic wave filter by obtaining the exciting electrode that includes at least a lower metallic layer, an intermediate layer that prevents corrosion of the lower metallic layer and an upper metallic layer which can melt in alkalic solution. SOLUTION: An exciting electrode 4 consists at least of a lower metallic layer 6, a semiconductor intermediate layer 7 that prevents corrosion of the layer 6, and an upper metallic layer 8 that performs fine adjustment of a center frequency. The electrode 4 and a reflector electrode are formed on a piezoelectric substrate 3. The layer 6 consists of an alloy that contains primarily Al, for example, and the layer 7 consists of silicon or various silicon materials and can protect the layer 6 from its corrosion, etc. The layer 8 consists of a metallic material such as pure Al, etc., that can melt in basic solution. Then a protective layer 9, i.e., a semiconductor layer of silicon or silicon oxide is formed on the DIT electrode 4, wherein specific resistance of the layer 9 is set at 10<2> to 10<7>Ω.cm.
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