Film bulk acoustic resonator and filter

A thin-film bulk acoustic wave and resonator technology, applied in piezoelectric devices/electrostrictive devices, components of piezoelectric devices or electrostrictive devices, material selection for piezoelectric devices or electrostrictive devices, etc. , which can solve problems such as characteristic deterioration

Active Publication Date: 2008-06-25
TAIYO YUDEN KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Characteristic degradation due to noise is observed in the frequency range A on the low frequency side of the transmission characteristics

Method used

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  • Film bulk acoustic resonator and filter
  • Film bulk acoustic resonator and filter
  • Film bulk acoustic resonator and filter

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Experimental program
Comparison scheme
Effect test

no. 1 approach

[0055] FIG. 9A illustrates a top view of the resonator according to the first embodiment. FIG. 9B illustrates a cross-sectional view taken along line A-A of FIG. 9A. FIG. 9C illustrates a cross-sectional view taken along line B-B of FIG. 9A. A cavity 46 (via hole) is formed in the Si (silicon) substrate 41 . On the substrate 41 , above the cavity 46 , a lower electrode 43 is provided. A piezoelectric thin film 44 made of AlN is provided on the lower electrode 43 . An upper electrode 45 is provided on the piezoelectric film 44 . The resonance region 50 is a region where the lower electrode 43 and the upper electrode 45 face each other across the piezoelectric film 44 . The supporting area 52 is composed of the lower electrode 43 and the piezoelectric film 44 on the cavity 46, and is arranged around the resonant area 50, except for the wiring portion 56 leading out the upper electrode 45 and its surroundings. The adjacent area 54 is composed of the substrate 41, the lower e...

no. 2 approach

[0111] Fig. 21 illustrates a schematic sectional view of a resonator according to a second embodiment. As shown in FIG. 21 , the supporting area 52 is composed of the piezoelectric film 44 and the upper electrode 45 located above the cavity 46 . The adjacent area 54 is composed of the substrate 41 , the piezoelectric film 44 and the upper electrode 45 . A cavity 46 is formed in the resonance region 50 as well as the support region 52 . The lower electrode 43 is formed in the resonance region 50 . The piezoelectric film 44 and the upper electrode 45 are formed in the resonance region 50 , the support region 52 and the adjacent region 54 . Other structures are the same as those of the first embodiment shown in FIG. 13 .

[0112]22A to 22C are diagrams illustrating calculated scattering characteristics of the resonance region 50, the support region 52, and the adjacent region 54 in the resonator according to the second embodiment. Fig. 22A corresponds to Fig. 15A. As shown i...

no. 3 approach

[0115] Fig. 23 illustrates a schematic cross-sectional view of a resonator according to a third embodiment. As shown in FIG. 23 , the supporting area 52 is composed of the lower electrode 43 and the piezoelectric film 44 located above the cavity 46 . Adjacent region 54 consists of piezoelectric film 44 over cavity 46 . The cavity 46 and the piezoelectric film 44 are formed in the resonant region 50 , the support region 52 and the adjacent region 54 . The lower electrode 43 is formed in the resonance region 50 and the support region 52 . The upper electrode 45 is formed in the resonance region 50 . Other structures are the same as those of the first embodiment shown in FIG. 13 .

[0116] 24A to 24C are diagrams showing the calculated scattering characteristics of the resonance region 50, the support region 52 and the adjacent region 54 in the resonator according to the third embodiment. Fig. 24A corresponds to Fig. 15A. As shown in FIG. 24B , in the support region 52, the ...

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PUM

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Abstract

A film bulk acoustic resonator includes a lower electrode that is formed on a void of a substrate or is formed so that a void is formed between the lower electrode and the substrate, a piezoelectric film that is formed on the lower electrode, an upper electrode that is formed on the piezoelectric film so as to have a resonance region facing the lower electrode through the piezoelectric film, a support region that is provided around the resonance region, has a width of 0.35 times to 0.65 times a wavelength of a wave propagating in a lateral direction, and transmits the wave passes, and an adjacent region that is provided around the support region and blocks the wave.

Description

technical field [0001] The present invention relates to thin film bulk acoustic resonators and filters, and more particularly, to thin film bulk acoustic resonators and filters comprising a cavity located below a resonance region in which upper and lower electrodes facing each other across the piezoelectric film. Background technique [0002] Because of the rapid spread of wireless devices such as mobile phones, there is an increasing demand for small and lightweight resonators and filters having the same. Dielectric filters and surface acoustic wave (SAW) filters have been mainly used so far. Recently, attention has been paid to piezoelectric thin film resonators and filters including piezoelectric thin film resonators, which have excellent characteristics particularly at high frequencies and which can be miniaturized and monolithically integrated. [0003] A resonator of the FBAR (Film Bulk Acoustic Resonator) type is known as a type of piezoelectric thin film resonator....

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H03H9/15H03H9/54H01L41/09H01L41/18H01L41/187H01L41/22H01L41/253H03H3/02H03H9/17
CPCH03H9/02118H03H3/02H03H9/174H03H9/173H03H9/17H10N30/80
Inventor 原基扬西原时弘上田政则远藤刚
Owner TAIYO YUDEN KK
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