| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an acoustic wave element capable of reducing spurious in the vicinity of resonant frequency and anti-resonant frequency.SOLUTION: The acoustic wave element comprises: a comb-like medium which is formed over a piezoelectric substrate in a pattern shape identical to that of an IDT electrode; the IDT electrode laminated over the medium with the upper surface thereof facing an excitation space; and a dielectric film which is formed between the medium and the IDT electrode to fill the space therebetween. The density of the IDT electrode can be set to be larger than the density of the piezoelectric substrate, the medium and the dielectric film. With this, SH wave can be transmitted while being convergent to the inside of the IDT electrode. Since the acoustic velocity of the SH wave is lowered, the difference in acoustic velocity between the SH wave and a Rayleigh wave transmitting on the surface of the board can be increased. As a result, an acoustic wave element can be achieved, in which the spurious is extremely small in the vicinity of resonant frequency of undesired spurious and major wave.</p> |
