Acoustic wave device

摘要

An acoustic wave device includes a piezoelectric substrate, an interdigital transducer (IDT) electrode provided on an upper surface of the piezoelectric substrate, a first dielectric film covering the upper surface of the piezoelectric substrate to cover the IDT electrode, and a second dielectric film covering an upper surface of the first dielectric film. The second dielectric film includes a thin portion positioned in a tip region of electrode fingers of the IDT electrode and a thick portion which is positioned in a middle region of the IDT electrode and is thicker than the thin portion. The acoustic wave device suppresses spurious emission and has superior passband characteristics.

主权项

1. An acoustic wave device comprising:
a piezoelectric substrate; an interdigital transducer (IDT) electrode provided on an upper surface of the piezoelectric substrate, the IDT electrode being configured to excite an acoustic wave propagating in a predetermined propagation direction; a first dielectric film covering the upper surface of the piezoelectric substrate to cover the IDT electrode; and a second dielectric film covering an upper surface of the first dielectric film, wherein the IDT electrode includes a first comb electrode and a second comb electrode facing each other, wherein the first comb electrode includes a first bus bar and a plurality of first electrode fingers extending from the first bus bar toward the second comb electrode, wherein the second comb electrode includes a second bus bar and a plurality of second electrode fingers extending from the second bus bar toward the first comb electrode, such that the plurality of second electrode fingers interdigitate with the plurality of first electrode fingers, wherein each of the plurality of first electrode fingers includes a first tip portion facing the second bus bar, wherein each of the plurality of second electrode fingers includes a second tip portion facing the first bus bar, wherein the IDT electrode defines:
a first tip region including the second tip portion of each of the plurality of second electrode fingers, the first tip region extending in the propagation direction;a second tip region including the first tip portion of each of the plurality of first electrode fingers, the second tip region extending in the propagation direction; anda middle region positioned between the first tip region and the second tip region, the middle region extending in the propagation direction, and wherein the second dielectric film includes:
a first thin portion positioned in the first tip region;a second thin portion positioned in the second tip region; anda thick portion positioned in the middle region, the thick portion being thicker than the first thin portion and the second thin portion.