| 摘要 |
PROBLEM TO BE SOLVED: To obtain a means by which a composite filter provided with a transmission/reception RF filter is formed on one piezoelectric substrate. SOLUTION: An aluminum film is formed on a wafer, a resist film with a width nearly a half of the width of the desired composite RF filter is sequentially coated while leaving the interval nearly equal to the film width, after the exposed aluminum film is removed, an aluminum alloy film containing prescribed copper is formed to the removed area, a reception RF filter of the composite RF filter is formed to the area of the aluminum film and a transmission RF filter is formed to the area of the aluminum alloy film.
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