Taiyo Yuden Co., Ltd.

Mamoru Ishida

Takashi Matsuda

Shinji Taniguchi

Yoshio Satoh

Ryo Iwaki

Tasuku Kawashima

An acoustic wave device includes a substrate, lower and upper electrodes provided over the substrate, a piezoelectric film that is provided over the substrate, is interposed between the lower and upper electrodes, and has a pair of through holes that sandwich a resonance region therebetween in a first direction, are provided along the resonance region, and are connected to an air gap that is formed between the substrate and the lower electrode and overlaps the resonance region in the plan view, the lower and upper electrodes overlapping across the piezoelectric film in the resonance region, and additional films that are not provided in a central region of the resonance region in the plan view and are provided in respective edge regions, which are located on respective sides of the central region in a second direction substantially orthogonal to the first direction in the plan view, of the resonance region.

Acoustic wave device, filter, multiplexer, and manufacturing method of acoustic wave device

An acoustic wave device includes a piezoelectric layer, the piezoelectric layer being a rotated Y-cut lithium niobate substrate or an X-cut lithium tantalate substrate; an upper conductive layer having a substantially consistent density, on or over the upper surface of the piezoelectric layer; a lower conductive layer having a substantially consistent density, on or below the lower surface of the piezoelectric layer; and a first additional film having a substantially consistent density, wherein at least one of the upper and lower conductive layers is mainly made of ruthenium, chrome, copper, molybdenum, tungsten, tantalum, platinum, rhodium, or iridium, and wherein at least a part of the first additional film is in the resonance region in the plan view, and the density of the first additional film is equal to or less than the density of aluminum.

Acoustic wave device and filter

A filter includes a series resonator including a first piezoelectric layer and first electrodes, and a parallel resonator including a second piezoelectric layer and second electrodes. Each of the first and second piezoelectric layers is a monocrystalline lithium niobate layers, has an X-axis orientation in a planar direction, and has a thickness direction in a direction obtained by a 105° rotation of a +Z-axis orientation toward a +Y-axis orientation. The first electrodes face each other across the first piezoelectric layer to form a first resonance region and are extracted from the first resonance region in a direction substantially parallel to the X-axis orientation of the first piezoelectric layer. The second electrodes face each other across the second piezoelectric layer to form a second resonance region and are extracted from the second resonance region in a direction substantially orthogonal to the X-axis orientation of the second piezoelectric layer.

Filter and multiplexer

An acoustic wave device includes: a piezoelectric substrate; electrodes sandwiching the piezoelectric substrate and exciting a thickness shear vibration in the piezoelectric substrate; and an edge region that is a region surrounding a center region of a resonance region, wherein a first region of the edge region is located on both sides of the center region in a first direction substantially parallel to a displacement direction of a thickness shear vibration, a second region of the edge region is located on both sides of the center region in a second direction substantially perpendicular to the first direction, a width of the second region is different from a width of the first region, and acoustic velocities of acoustic waves in the piezoelectric substrate in the first and second regions are less than that in the piezoelectric substrate in the center region.

Acoustic wave device, filter, and multiplexer

A piezoelectric thin film resonator includes: a substrate; a lower electrode located on the substrate through an air gap; a piezoelectric film located so as to have a resonance region where the lower electrode and an upper electrode face each other across the piezoelectric film and having a lower piezoelectric film and an upper piezoelectric film, in an extraction region where the lower electrode is extracted from the resonance region, a lower end of a first end face of the lower piezoelectric film being substantially aligned with or located further out than an outer periphery of the air gap, a second end face of the upper piezoelectric film being inclined, an upper end of the second end face being substantially aligned with or located further in than the outer periphery, the lower piezoelectric film having a substantially uniform film thickness between the first end face and the second end face.

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Tokyo, Japan

Mamoru Ishida