ELASTIC BOUNDARY WAVE DEVICE

摘要

Provided is an elastic boundary wave device wherein characteristics, such as filter characteristics and resonator characteristics, are improved. An elastic boundary wave device (1) is provided with a first medium (21) composed of a piezoelectric body, a second medium (22), a third medium (23), an IDT electrode (20), and a wiring electrode (24). The second medium (22) is formed on the first medium (21). The third medium (23) is formed on the second medium (22). The IDT electrode (20) is formed on the boundary between the first medium (21) and the second medium (22). The second medium (22) has a higher sound speed compared with the sound speeds of the first and the third mediums (21, 23). The sound speed of the third medium (23) is higher than that of the first medium (21). The wiring electrode (24) is formed on the third medium (23) such that at least a part of the wiring electrode overlaps the IDT electrode (20) in planar view. The thickness of the third medium (23) is 0.7 times the wavelength of elastic boundary waves excited by means of the IDT electrode (20) or more.