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Elastic wave device

An elastic wave device, elastic wave technology, applied in impedance networks, electrical components, piezoelectric/electrostrictive/magnetostrictive devices, etc., can solve problems such as stray

Active Publication Date: 2020-09-29
MURATA MFG CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] However, in the elastic wave device described in Patent Document 1, depending on the density, Young's modulus, and film thickness of the metal used for the IDT electrode, spurs may occur outside the band.

Method used

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  • Elastic wave device
  • Elastic wave device
  • Elastic wave device

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 2

[0082] The structure of Embodiment 2 is as follows.

[0083] Wavelength determined by electrode finger spacing = 2μm

[0084] Number of electrode fingers = infinite period

[0085] Duty cycle = 0.5

[0086] High-sonic member 2: a supporting substrate made of Si, with Euler angles of (0°, -45°, 30°).

[0087] Intermediate layer 12: SiO 2 Membrane, thickness 0.2λ

[0088] Piezoelectric layer 3: 50° Y-cut X-propagating LiTaO 3 , with a thickness of 0.2λ.

[0089] The lamination structure of the IDT electrode 4 and the reflectors 5 and 6: Al film / Ru film, the film thickness is Al film = 4% of λ, Ru film = 4% of λ. That is, the absolute film thickness in the IDT electrode 4 is set to be 8% of the wavelength λ.

[0090] From the above formula (2) and Table 4, Vsh0 and Vsp in the elastic wave device according to Embodiment 2 are as follows.

[0091] Vsh0=3458m / sec

[0092] Vsp=5640m / sec

[0093] In addition, Vsub is 5575 m / sec.

[0094] For comparison, an elastic wave devi...

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Abstract

The invention provides an elastic wave device capable of reducing spurious emission. In the elastic wave device (1), a high-sound-velocity member (2), a piezoelectric layer (3) comprising lithium tantalate, and an IDT electrode (4) are laminated. The sound velocity of the bulk wave propagating through the high-sound-velocity member (2) is higher than the sound velocity of the elastic wave propagating through the piezoelectric layer (3). The sound velocity Vsub of the fast transverse wave body wave propagating through the high sound velocity member (2) satisfies Vsh0 < = Vsub < = Vsp with respect to the sound velocity Vsh0 of the SH0 mode determined by formula (1) and the sound velocity Vsp of the spurious mode having a sound velocity equal to or greater than the SH0 mode.

Description

technical field [0001] The present invention relates to an elastic wave device in which a piezoelectric layer made of lithium tantalate is directly or indirectly laminated on a high-sonic member. Background technique [0002] Conventionally, elastic wave devices having a thin piezoelectric layer made of lithium tantalate have been proposed. In the elastic wave device described in Patent Document 1 below, a high-sonic member, a low-sonic film, a piezoelectric film, and an IDT electrode are stacked in this order. By using a high-sonic member and a low-sonic film, it is possible to confine elastic waves to the piezoelectric film. [0003] prior art literature [0004] patent documents [0005] Patent Document 1: WO2012 / 086639 [0006] In the elastic wave device described in Patent Document 1, the Q characteristic can be improved because it has the above-mentioned stacked structure. [0007] However, in the elastic wave device described in Patent Document 1, spurs may occur...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03H9/25H03H9/145H10N30/87
CPCH03H9/25H03H9/145H03H9/02228H03H9/02015H03H9/02062H03H9/02086H03H9/131H03H9/02818H03H9/02559H03H9/14538H03H9/6489H03H9/02574H03H9/178H03H9/0211H10N30/877
Inventor 永友翔大门克也
Owner MURATA MFG CO LTD