| 摘要 |
PURPOSE:To improve the reliability of a surface acoustic wave element by coating a reed screen electrode on a piezoelectric substrate with an insulation film made of tantalum pentoxide so as to prevent almost the short-circuit of the reed screen electrodes without causing the deterioration of characteristic of the surface acoustic wave element. CONSTITUTION:For example, Al is vapor-deposited on a crystal substrate 1 applied with mirror polishment by the sputtering method and the reed screen electrodes 2 and reflectors 3 are formed by etching it. The tantalum pentoxide is vapor-deposited and sputtered on them, and the pentoxide other than that of the reed screen electrode 2 is removed to formthe insulation film 5 of the pentoxide. In general, the propagation of the surface is disturbed by coating the insulation film on the piezoelectric substrate and it is considered that the characteristic of the surface acoustic wave element is decreased, but in coating the insualtion film only the reed screen electrode of the surface acoustic wave element, the decrease of the characteristic of the surface acoustic wave element is suppressed to be negligibly small or compensated by design. Then, the short-circuit of the reed screen electrodes is prevented almost completely by coating the insulation film to the reed screen electrode of the surface acoustic wave element. |
