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Surface acoustic wave filter

A surface acoustic wave and filter technology, applied in impedance networks, electrical components, etc., can solve the problems of electrical resistance degradation, stress fragility, etc., and achieve the effect of improving resistance

Inactive Publication Date: 2003-01-29
SKYWORKS PANASONIC FILTER SOLUTIONS JAPAN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, when the electrode is larger than a certain thickness, it is vulnerable to stress strain accompanying elastic surface wave transmission, and its resistance to electric power is degraded.

Method used

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  • Surface acoustic wave filter
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  • Surface acoustic wave filter

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Embodiment approach 1

[0037] figure 1 is a perspective view of a surface acoustic wave (SAW) filter in an embodiment of the present invention, figure 2 is the structure diagram of the filter. The SAW filter includes a substrate 1 and elastic wave resonators composed of electrodes 2 formed on the substrate, and is a so-called ladder-type surface acoustic wave filter in which five resonators are connected in a ladder shape. The electrode 2 is composed of a comb electrode 21 and a reflector 22 . In an embodiment of the present invention, the substrate 1 is a 36° rotated Y-cut substrate of lithium tantalate. In addition, in Embodiment 1, a bandpass filter having a comb pitch of about 0.6 μm and a center frequency of 1.8 GHz was described.

Embodiment 1

[0039] The electrode 102 of the first embodiment is the first layer 4 with a film thickness of 200 nm formed on the substrate 1 as shown in FIG. 3 .

Embodiment 2

[0040] The electrode 112 of Example 2 has, as shown in FIG. 4 , a first layer 4 with a film thickness of 200 nm that is sequentially stacked from the substrate 1 side and a grain boundary that prevents the Al atoms of the first layer from interfering with the substrate in the vertical direction. Diffuse layer 2 of 5.

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Abstract

In a surface acoustic wave (SAW) filter having a substrate and electrodes formed on the substrate, an electrode has a base layer, a first metal layer made of Al or an Al-based metal and oriented in a constant direction to the substrate, a second metal layer which prevents Al atoms of the first metal layer from migrating vertically to the substrate, and a third metal layer for adjusting the film thickness. Thus, a SAW filter having an arbitrary film thickness enables the simultaneous attainment of a film quality of difficulty in grain boundary diffusion and micronization of the grain diameter of a film effective in stress resistance. Therefore, the SAW filter blocks the migration of Al atoms of the electrode due to a stress loaded on the electrode with the propagation of the SAW, so that the filter becomes excellent in power resistance.

Description

technical field [0001] The present invention relates to a surface acoustic wave filter having electrodes such as comb electrodes formed on a substrate and a method of manufacturing the same. Background technique [0002] The conventional surface acoustic wave device disclosed in Japanese Unexamined Patent Publication No. 3-14308 has a piezoelectric substrate and a small amount of additives excellent in migration resistance such as Cu, Ti, Ni, Mg, and Pd added thereon, The crystal orientation is an epitaxially grown aluminum film electrode oriented in a certain direction, and the film has the function of preventing movement. [0003] Its electrode is a single-layer film composed of epitaxially grown aluminum film, and its electrode particle size grows to the same extent as the film thickness. Therefore, when the electrode is larger than a certain thickness, its vulnerability to stress strain accompanying surface acoustic wave transmission, and its resistance to electrical po...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03H3/08H03H9/02H03H9/145
CPCH03H9/02661H03H3/08H03H9/02929Y10T29/42H03H9/14541H03H9/02897
Inventor 高山了一中西秀和川崎哲生樱川彻横田康彦
Owner SKYWORKS PANASONIC FILTER SOLUTIONS JAPAN