| 摘要 |
PURPOSE:To prevent short-circuit due to the sticking of a metallic foreign material by providing a window hole with a proper shape by the patterning processing to the 2nd film, injecting an agent from the window hole so as to remove the 1st film. CONSTITUTION:A film 4 made of silicon dioxide being an insulation dielectric being the 1st film is formed to the surface of the part of an interdigital electrode 2 of a piezoelectric substrate 1 as a lower layer and the metallic film 5 as the 2nd film is formed on the film 4. The window hole 6 is formed by the patterning to the upper layer metallic film 5. In injecting a buffered fluoric acid through the window hole 6 finally, the dielectric substance (silicon dioxide) 4 is removed without giving damage to the resonator pattern provided already, the metallic film 5 having air gap with the interdigital electrode 2 is formed and the short-circuit due to a metallic foreign matter is avoided in assembling it into a case.
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