| 摘要 |
PROBLEM TO BE SOLVED: To increase the contact of interdigital electrodes with a piezoelectric substrate by stacking at least one interdigital electrode formed on the piezoelectric substrate on a 1st metal thin film as a base and providing a 2nd metal thin film, which consists principally of tantalum and is made intoα-tantalum at least partially. SOLUTION: On the piezoelectric substrate 2, an interdigital electrode(IDT) electrode) is formed of a comb-tooth electrode. An electrode finger 3a of the comb-tooth electrode has a 2nd metal thin film (tantalum thin film) 5b formed of tantalum on a 1st metal thin film. Here, the 1st metal thin film is formed of a laminated metal film in two-layered structure and a lower tungsten thin film 5a1 and an upper titanium thin film 5a2 are stacked. The tantalum thin film 5b is formed on the titanium thin film 5a2 and made intoα-tantalum. The specific resistance of the IDT electrode is therefore reduced to improve the insertion loss. |
