| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface acoustic wave device having a structure where an insulator layer is formed to cover an IDT electrode, and in which the reflection coefficient of the IDT is sufficiently high and deterioration of the characteristics due to undesired ripple can be suppressed. SOLUTION: The surface acoustic wave device comprises: a piezoelectric substrate 1 of LiNbO<SB>3</SB>where the square of an electromechanical coupling factor (k) is 0.025 or above; at least one electrode 4A formed on the piezoelectric substrate 1 and composed of a multilayer film made of a metal having a density higher than that of Al or an alloy principally composing this metal, or a multilayer film of a metal having a density higher than that of Al or alloy principally comprising this metal and another metal; a first insulator layer 2 formed in the residual region except the region where the at least one electrode 4A is formed and having a thickness substantially equal to that of the electrode; and a second insulator layer 6 formed to cover the electrode and the first insulator layer 2. The density of the electrode 4A is higher than that of the first insulator layer 2 of 1.5 or more times. COPYRIGHT: (C)2007,JPO&INPIT
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