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WO2016072270A1 - Dispositif piézoélectrique - Google Patents

Dispositif piézoélectrique Download PDF

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Publication number
WO2016072270A1
WO2016072270A1 PCT/JP2015/079767 JP2015079767W WO2016072270A1 WO 2016072270 A1 WO2016072270 A1 WO 2016072270A1 JP 2015079767 W JP2015079767 W JP 2015079767W WO 2016072270 A1 WO2016072270 A1 WO 2016072270A1
Authority
WO
WIPO (PCT)
Prior art keywords
piezoelectric
piezoelectric film
film
resonator
fixed layer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2015/079767
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English (en)
Japanese (ja)
Inventor
岸本諭卓
大村正志
木村哲也
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Murata Manufacturing Co Ltd
Original Assignee
Murata Manufacturing Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Murata Manufacturing Co Ltd filed Critical Murata Manufacturing Co Ltd
Publication of WO2016072270A1 publication Critical patent/WO2016072270A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
    • H03H9/25—Constructional features of resonators using surface acoustic waves

Definitions

  • the present invention relates to a piezoelectric device in which a conductor is formed on a piezoelectric film.
  • Patent Document 1 describes a piezoelectric resonator having a membrane structure.
  • a piezoelectric resonator having a membrane structure a piezoelectric film on which a resonator conductor pattern such as IDT is formed is supported on a support substrate by a fixed layer.
  • the region where the resonator conductor pattern is formed in the piezoelectric film is not in contact with the fixed layer. That is, the resonator conductor pattern forming region in the piezoelectric film is supported by the fixed layer so that the cavity is formed.
  • Patent Document 2 describes a piezoelectric resonator including an acoustic multilayer film.
  • the acoustic multilayer film is disposed between the piezoelectric film and the support substrate.
  • the characteristics of the resonator are deteriorated due to spurious effects such as higher order modes, and the characteristics of the piezoelectric device are reduced. It may deteriorate.
  • an object of the present invention is to provide a piezoelectric device capable of reducing the influence of spurious.
  • the piezoelectric resonator of the present invention includes a piezoelectric film, a resonator conductor pattern formed on the surface of the piezoelectric film, a support substrate, and a fixed layer that fixes the piezoelectric film to the support substrate.
  • the amount of warpage along a plurality of directions in a plane parallel to the surface of the piezoelectric film is not uniform.
  • the resonance frequency corresponding to the higher harmonics changes without changing the fundamental resonance frequency as compared with the piezoelectric resonator in which the piezoelectric film is arranged so as not to warp. As a result, spurious can be improved.
  • the amount of warp is preferably ⁇ 500 ⁇ m or less per 100 mm scanning distance in the direction parallel to the surface. Furthermore, the amount of warpage is preferably ⁇ 300 ⁇ m or less.
  • the fixed layer is not in contact with a portion where the resonator conductor pattern is formed in the piezoelectric film in a plan view.
  • the fixed layer may be an acoustic multilayer film in which high impedance layers and low impedance layers are alternately arranged.
  • the piezoelectric film is preferably a LiTaO 3 substrate or a LiNbO 3 substrate.
  • the resonator conductor pattern has a structure in which a plurality of comb-like conductors are combined, and it is preferable that the propagating high frequency is a plate wave.
  • the influence of spurious can be reduced and the characteristics of the device can be improved.
  • 1 is a plan view of a piezoelectric resonator according to a first embodiment of the present invention. It is side surface sectional drawing of the piezoelectric resonator which concerns on the 1st Embodiment of this invention. It is an enlarged view which shows the curvature of the piezoelectric film in the piezoelectric resonator which concerns on the 1st Embodiment of this invention. It is an impedance characteristic view of the piezoelectric resonator and the comparative example according to the first embodiment of the present invention. It is side surface sectional drawing which shows the shape in each process in the manufacturing method of the piezoelectric resonator which concerns on the 1st Embodiment of this invention. It is side surface sectional drawing of the piezoelectric resonator which concerns on the 2nd Embodiment of this invention.
  • FIG. 1 is a plan view of a piezoelectric resonator according to a first embodiment of the present invention.
  • FIG. 2 is a side cross-sectional view (corresponding to the AA cross-sectional view in FIG. 1) of the piezoelectric resonator according to the first embodiment of the present invention.
  • the piezoelectric resonator 10 includes a piezoelectric film 20, a fixed layer 30, and a support substrate 40.
  • the fixed layer 30 is bonded to the back surface of the piezoelectric film 20, and the support substrate 40 is bonded to the back surface of the fixed layer 30 (the surface opposite to the surface on which the piezoelectric film 20 abuts). With this configuration, the piezoelectric film 20 is supported on the support substrate 40 by the fixed layer 30.
  • the piezoelectric film 20 is a piezoelectric body such as LN (LiNbO 3 ) or LT (LiTaO 3 ).
  • the fixed layer 30 is an insulator such as SiO 2 .
  • the support substrate 40 is made of Si, sapphire, glass or the like.
  • Functional conductors 211 and 212 are formed on the surface of the piezoelectric film 20 (the surface opposite to the surface on the fixed layer 30 side).
  • the functional conductors 211 and 212 have a comb-teeth shape in plan view.
  • the functional conductors 211 and 212 are arranged so as to form a so-called IDT (Interdigital Transducer). With this configuration, a piezoelectric resonator is configured.
  • the void 300 is formed in the fixed layer 30.
  • the gap 300 is surrounded by the piezoelectric film 20, the fixed layer 30, and the support substrate 40. However, the gap 300 is inserted through the through hole 200 provided in the piezoelectric film 20.
  • the through-hole 200 is used when the gap 300 is formed.
  • the air gap 300 is provided so as to overlap a portion of the piezoelectric film 20 where the functional conductors 211 and 212 are formed when the piezoelectric resonator 10 is viewed in plan.
  • the back surface of the portion where the functional conductors 211 and 212 are formed in the piezoelectric film 20 is not in contact with (separated from) the fixed layer 30 and the support substrate 40.
  • the piezoelectric film 20 has a warp in the region where the functional conductors 211 and 212 are formed.
  • This warp has anisotropy in a plane parallel to the surface of the piezoelectric film 20. Specifically, as indicated by the dotted arrows in FIG. 1, the amount of warpage differs in a plurality of directions in the plane.
  • the warp amount along the direction parallel to the longitudinal direction of each finger conductor of each functional conductor 211, 212 is Wp1
  • the warp amount along the direction parallel to the finger conductor arrangement direction is Wp2
  • these two directions In contrast, a warp amount along a direction intersecting at a predetermined angle (for example, 45 °) is defined as Wp3.
  • the piezoelectric film 20 is warped so that Wp1 ⁇ Wp2 and Wp1 ⁇ Wp3.
  • FIG. 3 is an enlarged view showing warpage of the piezoelectric film in the piezoelectric resonator according to the first embodiment of the present invention. Note that FIG. 3 exaggerates the warpage.
  • the interval between adjacent finger conductors (functional conductors 211 and 212) is different from a state without warp.
  • the amount of change in the interval is determined by the amount of warpage.
  • the finger conductor is extended by the amount of the warp Wp2.
  • the ratio between the amount of change in the distance between the finger conductors due to warpage in the arrangement direction and the distance between the finger conductors without warping is the amount by which the length of the finger conductors changes due to the warp in the longitudinal direction of the finger conductors. And the ratio with the length of the finger conductor in a state without warping is large.
  • FIG. 4 is an impedance characteristic diagram of the piezoelectric resonator and the comparative example according to the first embodiment of the present invention.
  • the piezoelectric resonator 10 having the warp in the piezoelectric film 20 is compared with the piezoelectric resonator having no warp of the piezoelectric film (characteristic of the broken line in FIG. 4).
  • the resonance frequency of the fundamental wave hardly changes.
  • the resonance frequency of the higher harmonics changes.
  • the resonance frequency of the high-order harmonic shifts to the high frequency side.
  • the spurious characteristics of the piezoelectric resonator 10 can be improved.
  • the spurious characteristics can be improved by keeping the resonance frequency of the higher harmonics away from the resonance frequency of the fundamental wave.
  • the piezoelectric resonator 10 with improved spurious characteristics can be realized. Further, by using the configuration of the present embodiment, spurious characteristics can be improved without changing the arrangement pitch of the functional conductors 211 and 212, that is, without changing the shape of the functional conductors 211 and 212.
  • FIG. 5 is a side cross-sectional view showing the shape at each step in the method for manufacturing a piezoelectric resonator according to the first embodiment of the present invention.
  • a sacrificial layer 31 is formed on the back surface of the piezoelectric substrate 20P having a predetermined thickness.
  • the sacrificial layer 31 is formed so as to overlap with and include a portion where the functional conductors 211 and 212 are formed in a process described later.
  • the sacrificial layer 31 is, for example, ZnO.
  • the fixed layer 30 is formed on the back surface of the piezoelectric substrate 20P so as to cover the sacrificial layer 31 and the back surface of the piezoelectric substrate 20P.
  • the fixed layer 30 is polished and planarized from the surface of the fixed layer 30 opposite to the surface in contact with the piezoelectric substrate 20P and the sacrificial layer 31.
  • the planarization refers to a process of removing a portion protruding by the sacrificial layer 31 and keeping the surface roughness within a predetermined range.
  • the support substrate 40 is bonded to the flattened surface of the fixed layer 30.
  • a resin adhesive is used for bonding.
  • the piezoelectric substrate 20P is polished to form the piezoelectric film 20.
  • the planarization refers to a process of uniformly reducing the thickness of the piezoelectric film 20 and keeping the surface roughness within a predetermined range.
  • the fixed layer 30 is made of a material that applies a compressive stress to the piezoelectric substrate 20P.
  • the fixed layer 30 is the above-described SiO 2 .
  • the fixed layer 30 is formed on the back surface of the sacrificial layer 31 and the piezoelectric substrate 20P in an environment where the temperature is increased to a predetermined temperature (for example, 80 °). As a result, the fixed layer 30 is cooled, and compressive stress is applied to the piezoelectric substrate 20P, whereby an anisotropic warp can be generated in the piezoelectric substrate 20P.
  • the warp is preferably less than 500 ⁇ m at a scanning distance of 100 mm in each direction in the plane.
  • the warp is more preferably less than 300 ⁇ m at a scanning distance of 100 mm in each direction within the plane.
  • a through hole 200 is formed in the piezoelectric film 20.
  • the sacrificial layer 31 is removed through the through hole 200.
  • the sacrificial layer 31 is removed by wet etching.
  • voids 300 are formed in the fixed layer 30.
  • the piezoelectric resonator 10 is formed by using the above manufacturing method.
  • FIG. 6 is a side sectional view of the piezoelectric resonator according to the second embodiment of the present invention.
  • the piezoelectric resonator 10A according to the present embodiment is different from the piezoelectric resonator 10 according to the first embodiment in the configuration of the fixed layer 30.
  • the fixed layer 30 is configured by the acoustic multilayer film 60.
  • the acoustic multilayer film 60 has a structure in which layers having high acoustic impedance and layers having low acoustic impedance are alternately stacked. Specifically, it has a structure in which SiO 2 layers and AlN layers are alternately laminated.
  • At least one layer constituting the acoustic multilayer film 60 is formed to have anisotropy in warping.
  • the piezoelectric resonator 10A capable of improving the spurious characteristics can be realized as in the first embodiment.
  • the piezoelectric resonators 10 and 10A described above are illustrated as examples of a plate-wave piezoelectric resonator, but may be a bulk-wave piezoelectric resonator.
  • a plate-wave piezoelectric resonator the effect of wave confinement by a membrane structure or an acoustic multilayer film has a great influence on the characteristics of the resonator. For this reason, it is easy to receive the influence of the above-mentioned spurious.
  • the influence of spurious can be suppressed. Therefore, a piezoelectric resonator for plate wave with higher performance can be realized.
  • piezoelectric resonator is shown in the present embodiment, it can be applied to a filter using the piezoelectric resonator and various piezoelectric devices.
  • Piezoelectric resonator 20 Piezoelectric film 20P: Piezoelectric substrate 30: Fixed layer 31: Sacrificial layer 40: Support substrate 60: Acoustic multilayer film 91: Sacrificial layer 200: Through hole 211, 212: Functional conductor 300: Air gap

Landscapes

  • Physics & Mathematics (AREA)
  • Acoustics & Sound (AREA)
  • Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)

Abstract

L'invention concerne un résonateur piézoélectrique (10) pourvu d'un film piézoélectrique (20). Des conducteurs de fonction (211, 212) sont formés sur la surface du film piézoélectrique (20). Le résonateur piézoélectrique (10) est pourvu d'un substrat de support (40) et d'une couche de fixation (30). La couche de fixation (30) fixe le film piézoélectrique (20) au substrat de support (40). Le degré de gauchissement n'est pas uniforme dans une pluralité de directions dans un plan parallèle à la surface du film piézoélectrique (20). Dans l'état mentionné ci-dessus, le film piézoélectrique (20) est supporté par le substrat de support (40), la couche de fixation (30) étant intercalée entre ceux-ci.
PCT/JP2015/079767 2014-11-05 2015-10-22 Dispositif piézoélectrique Ceased WO2016072270A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2014-224861 2014-11-05
JP2014224861 2014-11-05

Publications (1)

Publication Number Publication Date
WO2016072270A1 true WO2016072270A1 (fr) 2016-05-12

Family

ID=55908997

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2015/079767 Ceased WO2016072270A1 (fr) 2014-11-05 2015-10-22 Dispositif piézoélectrique

Country Status (1)

Country Link
WO (1) WO2016072270A1 (fr)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002043646A (ja) * 2000-07-19 2002-02-08 Murata Mfg Co Ltd 薄膜、薄膜の製造方法および電子部品
JP2004159339A (ja) * 2002-11-07 2004-06-03 Infineon Technologies Ag Ｂａｗ共振器の音響反射器
JP2004357306A (ja) * 2003-05-29 2004-12-16 Samsung Electronics Co Ltd 支持台を有する薄膜バルク音響共振器およびその製造方法
WO2008084578A1 (fr) * 2006-12-25 2008-07-17 Murata Manufacturing Co., Ltd. Résonateur en film mince piézoélectrique
JP2009005143A (ja) * 2007-06-22 2009-01-08 Ngk Insulators Ltd 圧電薄膜デバイス
JP2010028371A (ja) * 2008-07-17 2010-02-04 Fujitsu Ltd 共振デバイス、通信モジュール、通信装置、共振デバイスの製造方法
WO2011052551A1 (fr) * 2009-10-30 2011-05-05 株式会社村田製作所 Dispositif piézoélectrique et procédé de fabrication d'un dispositif piézoélectrique
WO2012086441A1 (fr) * 2010-12-24 2012-06-28 株式会社村田製作所 Dispositif à ondes élastiques et procédé de fabrication correspondant

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002043646A (ja) * 2000-07-19 2002-02-08 Murata Mfg Co Ltd 薄膜、薄膜の製造方法および電子部品
JP2004159339A (ja) * 2002-11-07 2004-06-03 Infineon Technologies Ag Ｂａｗ共振器の音響反射器
JP2004357306A (ja) * 2003-05-29 2004-12-16 Samsung Electronics Co Ltd 支持台を有する薄膜バルク音響共振器およびその製造方法
WO2008084578A1 (fr) * 2006-12-25 2008-07-17 Murata Manufacturing Co., Ltd. Résonateur en film mince piézoélectrique
JP2009005143A (ja) * 2007-06-22 2009-01-08 Ngk Insulators Ltd 圧電薄膜デバイス
JP2010028371A (ja) * 2008-07-17 2010-02-04 Fujitsu Ltd 共振デバイス、通信モジュール、通信装置、共振デバイスの製造方法
WO2011052551A1 (fr) * 2009-10-30 2011-05-05 株式会社村田製作所 Dispositif piézoélectrique et procédé de fabrication d'un dispositif piézoélectrique
WO2012086441A1 (fr) * 2010-12-24 2012-06-28 株式会社村田製作所 Dispositif à ondes élastiques et procédé de fabrication correspondant

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