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WO2014007015A1 - Piezoelectric thin film element and method for manufacturing same - Google Patents

Piezoelectric thin film element and method for manufacturing same Download PDF

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Publication number
WO2014007015A1
WO2014007015A1 PCT/JP2013/065462 JP2013065462W WO2014007015A1 WO 2014007015 A1 WO2014007015 A1 WO 2014007015A1 JP 2013065462 W JP2013065462 W JP 2013065462W WO 2014007015 A1 WO2014007015 A1 WO 2014007015A1
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Prior art keywords
thin film
piezoelectric thin
electrode
film element
silicon
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PCT/JP2013/065462
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French (fr)
Japanese (ja)
Inventor
観照 山本
伸介 池内
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株式会社村田製作所
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Priority to JP2014523652A priority Critical patent/JPWO2014007015A1/en
Publication of WO2014007015A1 publication Critical patent/WO2014007015A1/en

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/87—Electrodes or interconnections, e.g. leads or terminals
    • H10N30/877—Conductive materials
    • H10N30/878—Conductive materials the principal material being non-metallic, e.g. oxide or carbon based
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/06—Forming electrodes or interconnections, e.g. leads or terminals
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/07—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base
    • H10N30/074—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing
    • H10N30/076—Forming of piezoelectric or electrostrictive parts or bodies on an electrical element or another base by depositing piezoelectric or electrostrictive layers, e.g. aerosol or screen printing by vapour phase deposition
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/80—Constructional details
    • H10N30/85—Piezoelectric or electrostrictive active materials
    • H10N30/853—Ceramic compositions
    • H10N30/8542—Alkali metal based oxides, e.g. lithium, sodium or potassium niobates

Definitions

  • the present invention relates to a piezoelectric thin film element and a manufacturing method thereof.
  • a piezoelectric thin film element provided with a piezoelectric thin film and an electrode is known.
  • Such a piezoelectric thin film element is used as various sensors such as an angular velocity sensor and an acceleration sensor, an actuator, a high frequency filter, and the like.
  • Patent Document 1 a piezoelectric thin film made of sodium potassium niobate (general formula: (K x Na 1-x ) NbO 3 (0 ⁇ x ⁇ 1)) is provided on an electrode made of Pt.
  • a piezoelectric thin film element is disclosed.
  • a piezoelectric thin film made of potassium sodium niobate is formed on a Pt layer constituting an electrode made of Pt.
  • a piezoelectric thin film made of potassium sodium niobate is formed on the Pt layer, cracks are likely to be formed in the piezoelectric thin film when the piezoelectric thin film element is manufactured or when a temperature change occurs in the piezoelectric thin film element. is there.
  • the main object of the present invention is to provide a piezoelectric thin film element in which cracks are hardly formed in the piezoelectric thin film and a method for manufacturing the same.
  • the piezoelectric thin film element of the present invention includes a piezoelectric thin film, a first electrode, and a second electrode.
  • the piezoelectric thin film contains an alkali niobic acid compound.
  • the first electrode is provided on one main surface of the piezoelectric thin film.
  • the second electrode is provided on the other main surface of the piezoelectric thin film.
  • the first electrode is made of silicon.
  • a seed layer is provided between the piezoelectric thin film and the first electrode.
  • the seed layer is a perovskite oxide such as LaNiO 3 , LaScO 3 , LaGaO 3 , KNbO 3 , NaNbO 3 , SrRuO 3 , ZnO, TiO 2 , CeO 2, etc. And at least one selected from the group consisting of nitrides such as AlN and ZrN.
  • a piezoelectric thin film containing an alkali niobic acid compound is formed on an electrode made of silicon.
  • the present invention it is possible to provide a piezoelectric thin film element in which cracks are hardly formed in the piezoelectric thin film and a method for manufacturing the same.
  • FIG. 1 is a schematic cross-sectional view of a piezoelectric thin film element according to a first embodiment of the present invention.
  • FIG. 2 is a schematic cross-sectional view of a piezoelectric thin film element according to a second embodiment of the present invention.
  • FIG. 3 is a schematic cross-sectional view of a piezoelectric thin film element according to a third embodiment of the present invention.
  • 4 is a laser microscope image of the surface of the piezoelectric thin film formed in Example 1.
  • FIG. FIG. 5 is a laser microscope image of the surface of the piezoelectric thin film formed in Example 2.
  • FIG. 6 is a laser microscope image of the surface of the piezoelectric thin film formed in Comparative Example 1.
  • FIG. 1 is a schematic cross-sectional view of a piezoelectric thin film element 1 according to a first embodiment of the present invention.
  • the piezoelectric thin film element 1 according to the present embodiment will be described with reference to FIG.
  • the piezoelectric thin film element 1 has a piezoelectric thin film 4.
  • the piezoelectric thin film 4 contains an alkali niobic acid compound.
  • the piezoelectric thin film 4 is preferably made of a material mainly composed of an alkali niobic acid compound. More preferably, the alkali niobate compound is an alkali niobate compound having a perovskite structure.
  • the alkali niobate compound is preferably a potassium sodium niobate compound containing potassium, sodium and niobium.
  • Examples of the potassium sodium niobate compound include compounds represented by the following general formula (1).
  • A is at least one element selected from the group consisting of Li, Ag, Ca, Sr, Bi, and Gd.
  • B is at least one element selected from the group consisting of Ta, Zr, Ti, Al, Sc and Hf.
  • a, b, and c are numbers satisfying the conditions of 0 ⁇ a ⁇ 0.9, 0 ⁇ b ⁇ 0.3, 0 ⁇ a + b ⁇ 0.9, and 0 ⁇ c ⁇ 0.3.
  • the thickness of the piezoelectric thin film 4 is usually about 1 ⁇ m to 3 ⁇ m, and preferably about 2 ⁇ m to 3 ⁇ m.
  • the first electrode 3 is provided on the first surface 4 a of the piezoelectric thin film 4. Specifically, the first electrode 3 is provided so as to be in contact with the first surface 4 a of the piezoelectric thin film 4.
  • the first electrode 3 is a lower electrode.
  • the first electrode 3 also serves as a support layer that increases the rigidity of the piezoelectric thin film element 1.
  • the first electrode 3 can be formed, for example, by cutting and polishing an ingot, or can be formed by a film forming method such as a sputtering method or a vapor deposition method.
  • the first electrode 3 is made of silicon. Specifically, the silicon constituting the first electrode 3 is low resistance silicon. Low-resistance silicon is obtained by doping silicon with arsenic, phosphorus, or the like and having an electric resistance lower than that of pure silicon. The resistivity of the low-resistance silicon constituting the first electrode 3 is preferably 10 ⁇ 3 ⁇ cm or less.
  • the surface layer by the side of the piezoelectric thin film 4 should just be comprised with the silicon
  • the thickness of the first electrode 3 is usually about 1 ⁇ m to 800 ⁇ m, and is preferably 5 ⁇ m or more in consideration of the role as a support layer.
  • a second electrode 5 is provided on the second surface 4 b of the piezoelectric thin film 4. Specifically, the second electrode 5 is provided so as to contact the second surface 4 b of the piezoelectric thin film 4.
  • the second electrode 5 is an upper electrode.
  • the second electrode 5 can be formed by a film forming method such as a sputtering method or a vapor deposition method.
  • the second electrode 5 is made of a metal such as low resistance silicon, Pt, Au, Ag, Ru, Ir, Cu, Ti, Al, an alloy mainly containing at least one of these metals.
  • the thickness of the second electrode 5 is usually about 0.05 ⁇ m to 0.3 ⁇ m, and preferably about 0.1 ⁇ m to 0.2 ⁇ m.
  • a piezoelectric thin film made of potassium sodium niobate is formed on a Pt layer constituting an electrode made of Pt
  • a piezoelectric film is produced when the piezoelectric thin film element is manufactured or when a temperature change occurs in the piezoelectric thin film element. In some cases, cracks are easily formed in the thin film.
  • the first electrode 3 made of silicon is provided on the first main surface 4 a of the piezoelectric thin film 4. For this reason, cracks are unlikely to occur in the piezoelectric thin film 4. Although details of the reason why cracks are less likely to occur in the piezoelectric thin film 4 are not clear, such as differences in thermal expansion coefficient and lattice mismatch between the first electrode 3 made of silicon and the piezoelectric thin film 4 containing an alkali niobate compound. It is considered that the stress applied to the piezoelectric thin film 4 is relaxed due to a plurality of factors.
  • the piezoelectric thin film element 1 can be manufactured as follows, for example. First, the first electrode 3 made of silicon is formed by a film forming method such as a sputtering method or an evaporation method. Next, the piezoelectric thin film 4 made of a potassium sodium niobate compound is formed on the first electrode 3 by a film forming method such as sputtering or vapor deposition. For example, when the potassium sodium niobate compound constituting the piezoelectric thin film 4 is a compound represented by the general formula (1), the piezoelectric thin film 4 is formed by, for example, a high frequency sputtering method.
  • the second electrode 5 is formed on the piezoelectric thin film 4 by a film forming method such as sputtering or vapor deposition. Before or after the second electrode 5 is formed, the piezoelectric thin film 4 may be annealed by a rapid thermal processing apparatus (RTA apparatus: Rapid Thermal Annealing apparatus) or the like. The piezoelectric thin film element 1 is obtained as described above.
  • RTA apparatus Rapid Thermal Annealing apparatus
  • FIG. 2 is a schematic cross-sectional view of a piezoelectric thin film element 1 according to the second embodiment of the present invention.
  • the piezoelectric thin film element 1 has a support layer 2.
  • the first electrode 3 is provided on the support layer 2. Since the piezoelectric thin film element 1 has the support layer 2, the rigidity of the piezoelectric thin film element 1 is enhanced.
  • the material which comprises the support layer 2 is not specifically limited.
  • the material constituting the support layer 2 examples include silicon, low-temperature fired ceramics, insulating ceramics such as Al 2 O 3 , piezoelectric single-pieces such as LiTaO 3 , LiNbO 3 , and quartz, semiconductors such as SiC, GaAs, and GaN, Glass etc. are mentioned.
  • the support layer 2 is made of silicon, the support layer 2 is preferably made of silicon doped with arsenic or phosphorus and having a resistivity of 10 ⁇ 2 ⁇ cm or less.
  • arsenic or phosphorus is doped to a depth of about 0.01 to 0.1 ⁇ m from one main surface of a silicon substrate or the like, and the surface layer with a reduced resistance is used as the first electrode. 3 and other portions may be the support layer 2.
  • the thickness of the support layer 2 is usually about 50 ⁇ m to 800 ⁇ m.
  • FIG. 3 is a schematic cross-sectional view of a piezoelectric thin film element 1 according to a third embodiment of the present invention.
  • a seed layer 6 is provided between the piezoelectric thin film 4 and the first electrode 3.
  • the crystal orientation of the alkali niobate compound constituting the piezoelectric thin film 4 can be enhanced. For this reason, it can suppress more effectively that a crack is formed in the piezoelectric thin film 4.
  • the seed layer 6 is made of a LaNiO 3, LaScO 3, LaGaO 3 , KNbO 3, NaNbO 3, perovskite oxide such as SrRuO 3, ZnO, TiO 2, oxides such as CeO 2, AlN, nitrides such as ZrN It is preferably composed of at least one selected from the group, and more preferably composed of LaNiO 3 . Note that a film formed by forming the same material as the piezoelectric thin film 4 at a temperature of about 300 ° C. may be used as the seed layer 6.
  • the thickness of the seed layer 6 is preferably 10 nm or more, and preferably 200 nm or less.
  • Example 1 A silicon substrate having a thickness of 500 ⁇ m is prepared, and arsenic is doped to a depth of about 0.01 to 0.1 ⁇ m from one main surface of the silicon substrate, so that the surface layer whose resistance has been reduced is the first electrode. 3 and a low resistance silicon substrate in which the other part constitutes the support layer 2 was formed.
  • the temperature of the first electrode 3 is 600 ° C.
  • the sputtering pressure is 0.1.
  • FIG. 4 shows a laser microscope image (within a field of view of 125 ⁇ m on one side) of the surface of the piezoelectric thin film 4 formed in Example 1.
  • Example 2 A silicon substrate having a thickness of 500 ⁇ m is prepared, and arsenic is doped to a depth of about 0.01 to 0.1 ⁇ m from one main surface of the silicon substrate, so that the surface layer whose resistance has been reduced is the first electrode. 3 and a low resistance silicon substrate in which the other part constitutes the support layer 2 was formed.
  • the temperature of the first electrode 3 is 300 ° C.
  • the sputtering pressure is 0.1.
  • a seed layer 6 of LaNiO 3 having a thickness of 30 nm was formed by sputtering using a target having a composition of LaNiO 3 under the condition of 27 Pa.
  • the temperature of the first electrode 3 is 600 ° C.
  • the sputtering pressure is 0.3 Pa.
  • a piezoelectric thin film 4 having a thickness of 2 ⁇ m and made of a potassium sodium niobate compound was formed by sputtering using a target having a composition of (K 0.5 , Na 0.5 ) NbO 3 under the conditions.
  • FIG. 5 shows a laser microscope image (within a field of view of 125 ⁇ m on one side) of the surface of the piezoelectric thin film 4 formed in Example 2.
  • a silicon substrate having a thickness of 300 ⁇ m and a thermal oxide film having a thickness of 700 nm formed on the surface was prepared.
  • An adhesion layer made of TiO 2 having a thickness of 20 nm was formed on the silicon substrate by sputtering.
  • a first electrode made of Pt and having a thickness of 100 nm was formed on the adhesion layer by sputtering under the conditions that the temperature of the silicon substrate was 430 ° C., the Ar atmosphere, and the sputtering pressure was 0.4 Pa.
  • the temperature of the silicon substrate is 300 ° C.
  • the sputtering pressure is 0.27 Pa.
  • a seed layer having a thickness of 30 nm and made of LaNiO 3 was formed by a sputtering method using a target having a composition of LaNiO 3 .
  • the temperature of the silicon substrate is 600 ° C.
  • the sputtering pressure is 0.3 Pa
  • a piezoelectric thin film having a thickness of 2 ⁇ m and made of a potassium sodium niobate compound was formed by sputtering using a target having a composition of K 0.5 , Na 0.5 ) NbO 3 .
  • FIG. 6 shows a laser microscope image (within a field of view of 125 ⁇ m on one side) of the surface of the piezoelectric thin film formed in Comparative Example 1.
  • a silicon substrate having a thickness of 300 ⁇ m and a thermal oxide film having a thickness of 700 nm formed on the surface was prepared.
  • An adhesion layer made of TiO 2 having a thickness of 20 nm was formed on the silicon substrate by sputtering.
  • a first electrode made of Pt and having a thickness of 100 nm was formed on the adhesion layer by sputtering under the conditions that the temperature of the silicon substrate was 430 ° C., the Ar atmosphere, and the sputtering pressure was 0.4 Pa.
  • the temperature of the silicon substrate is 600 ° C.
  • the partial pressure of O 2 / (Ar partial pressure + O 2 partial pressure) 0.1
  • the sputtering pressure is 0.3 Pa.
  • a piezoelectric thin film made of a potassium sodium niobate compound and having a thickness of 2 ⁇ m was formed by sputtering using a target having a composition of (K 0.5 , Na 0.5 ) NbO 3 .

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Abstract

Provided are: a piezoelectric thin film element wherein cracks are not easily formed in a piezoelectric thin film; and a method for manufacturing the piezoelectric thin film element. A piezoelectric thin film element (1) is provided with a piezoelectric thin film (4), a first electrode (3), and a second electrode (5). The piezoelectric thin film (4) contains an alkaline niobic acid compound. The first electrode (3) is provided on a main surface (4a) on one side of the piezoelectric thin film (4). The second electrode (5) is provided on a main surface (4b) on the other side of the piezoelectric thin film (4). The first electrode (3) is formed of silicon.

Description

圧電薄膜素子及びその製造方法Piezoelectric thin film element and manufacturing method thereof
　本発明は、圧電薄膜素子及びその製造方法に関する。 The present invention relates to a piezoelectric thin film element and a manufacturing method thereof.
　従来、圧電薄膜と電極とが設けられた圧電薄膜素子が知られている。このような圧電薄膜素子は、角速度センサや加速度センサなどの各種センサ、アクチュエータ、高周波フィルタなどとして用いられる。 Conventionally, a piezoelectric thin film element provided with a piezoelectric thin film and an electrode is known. Such a piezoelectric thin film element is used as various sensors such as an angular velocity sensor and an acceleration sensor, an actuator, a high frequency filter, and the like.
　例えば、特許文献１には、Ｐｔからなる電極の上に、ニオブ酸カリウムナトリウム（一般式：（ＫｘＮａ１－ｘ）ＮｂＯ３（０＜ｘ＜１））からなる圧電薄膜が設けられた、圧電薄膜素子が開示されている。 For example, in Patent Document 1, a piezoelectric thin film made of sodium potassium niobate (general formula: (K x Na 1-x ) NbO 3 (0 <x <1)) is provided on an electrode made of Pt. A piezoelectric thin film element is disclosed.
特開２００９－２９５７８６号公報JP 2009-295786 A
　このような圧電薄膜素子の製造工程においては、一般に、Ｐｔからなる電極を構成するＰｔ層の上にニオブ酸カリウムナトリウムからなる圧電薄膜を形成する。しかしながら、Ｐｔ層の上にニオブ酸カリウムナトリウムからなる圧電薄膜を形成すると、圧電薄膜素子の製造時や、圧電薄膜素子に温度変化が生じた際に、圧電薄膜にクラックが形成されやすくなる場合がある。 In the manufacturing process of such a piezoelectric thin film element, generally, a piezoelectric thin film made of potassium sodium niobate is formed on a Pt layer constituting an electrode made of Pt. However, when a piezoelectric thin film made of potassium sodium niobate is formed on the Pt layer, cracks are likely to be formed in the piezoelectric thin film when the piezoelectric thin film element is manufactured or when a temperature change occurs in the piezoelectric thin film element. is there.
　本発明は、圧電薄膜にクラックが形成されにくい圧電薄膜素子及びその製造方法を提供することを主な目的とする。 The main object of the present invention is to provide a piezoelectric thin film element in which cracks are hardly formed in the piezoelectric thin film and a method for manufacturing the same.
　本発明の圧電薄膜素子は、圧電薄膜と、第１の電極と、第２の電極とを備える。圧電薄膜は、アルカリニオブ酸系化合物を含む。第１の電極は、圧電薄膜の一方側主面に設けられている。第２の電極は、圧電薄膜の他方側主面に設けられている。第１の電極は、シリコンからなる。 The piezoelectric thin film element of the present invention includes a piezoelectric thin film, a first electrode, and a second electrode. The piezoelectric thin film contains an alkali niobic acid compound. The first electrode is provided on one main surface of the piezoelectric thin film. The second electrode is provided on the other main surface of the piezoelectric thin film. The first electrode is made of silicon.
　本発明の圧電薄膜素子のある特定の局面では、圧電薄膜と、第１の電極との間には、シード層が設けられている。 In a specific aspect of the piezoelectric thin film element of the present invention, a seed layer is provided between the piezoelectric thin film and the first electrode.
　本発明の圧電薄膜素子の他の特定の局面では、シード層が、ＬａＮｉＯ３，ＬａＳｃＯ３，ＬａＧａＯ３，ＫＮｂＯ３，ＮａＮｂＯ３，ＳｒＲｕＯ３などのペロブスカイト型酸化物、ＺｎＯ，ＴｉＯ２，ＣｅＯ２などの酸化物、ＡｌＮ，ＺｒＮなどの窒化物からなる群から選択された少なくとも１種により構成されている。 In another specific aspect of the piezoelectric thin film element of the present invention, the seed layer is a perovskite oxide such as LaNiO 3 , LaScO 3 , LaGaO 3 , KNbO 3 , NaNbO 3 , SrRuO 3 , ZnO, TiO 2 , CeO 2, etc. And at least one selected from the group consisting of nitrides such as AlN and ZrN.
　本発明の圧電薄膜素子の製造方法では、シリコンからなる電極の上に、アルカリニオブ酸系化合物を含む圧電薄膜を形成する。 In the method for manufacturing a piezoelectric thin film element of the present invention, a piezoelectric thin film containing an alkali niobic acid compound is formed on an electrode made of silicon.
　本発明によれば、圧電薄膜にクラックが形成されにくい圧電薄膜素子及びその製造方法を提供することができる。 According to the present invention, it is possible to provide a piezoelectric thin film element in which cracks are hardly formed in the piezoelectric thin film and a method for manufacturing the same.
図１は、本発明の第１の実施形態に係る圧電薄膜素子の略図的断面図である。FIG. 1 is a schematic cross-sectional view of a piezoelectric thin film element according to a first embodiment of the present invention. 図２は、本発明の第２の実施形態に係る圧電薄膜素子の略図的断面図である。FIG. 2 is a schematic cross-sectional view of a piezoelectric thin film element according to a second embodiment of the present invention. 図３は、本発明の第３の実施形態に係る圧電薄膜素子の略図的断面図である。FIG. 3 is a schematic cross-sectional view of a piezoelectric thin film element according to a third embodiment of the present invention. 図４は、実施例１で形成した圧電薄膜の表面のレーザー顕微鏡像である。4 is a laser microscope image of the surface of the piezoelectric thin film formed in Example 1. FIG. 図５は、実施例２で形成した圧電薄膜の表面のレーザー顕微鏡像である。FIG. 5 is a laser microscope image of the surface of the piezoelectric thin film formed in Example 2. 図６は、比較例１で形成した圧電薄膜の表面のレーザー顕微鏡像である。FIG. 6 is a laser microscope image of the surface of the piezoelectric thin film formed in Comparative Example 1.
　以下、本発明を実施した好ましい形態の一例について説明する。但し、下記の実施形態は、単なる例示である。本発明は、下記の実施形態に何ら限定されない。 Hereinafter, an example of a preferable embodiment in which the present invention is implemented will be described. However, the following embodiment is merely an example. The present invention is not limited to the following embodiments.
　また、実施形態等において参照する各図面において、実質的に同一の機能を有する部材は同一の符号で参照することとする。また、実施形態等において参照する図面は、模式的に記載されたものであり、図面に描画された物体の寸法の比率などは、現実の物体の寸法の比率などとは異なる場合がある。図面相互間においても、物体の寸法比率等が異なる場合がある。具体的な物体の寸法比率等は、以下の説明を参酌して判断されるべきである。 In each drawing referred to in the embodiment and the like, members having substantially the same function are referred to by the same reference numerals. The drawings referred to in the embodiments and the like are schematically described, and the ratio of the dimensions of the objects drawn in the drawings may be different from the ratio of the dimensions of the actual objects. The dimensional ratio of the object may be different between the drawings. The specific dimensional ratio of the object should be determined in consideration of the following description.
　図１は、本発明の第１の実施形態に係る圧電薄膜素子１の略図的断面図である。以下、図１を参照しながら、本実施形態に係る圧電薄膜素子１について説明する。 FIG. 1 is a schematic cross-sectional view of a piezoelectric thin film element 1 according to a first embodiment of the present invention. Hereinafter, the piezoelectric thin film element 1 according to the present embodiment will be described with reference to FIG.
　図１に示されるように、圧電薄膜素子１は、圧電薄膜４を有する。圧電薄膜４は、アルカリニオブ酸系化合物を含む。圧電薄膜４は、アルカリニオブ酸系化合物を主とする材料からなることが好ましい。アルカリニオブ酸系化合物は、ペロブスカイト型構造を有するアルカリニオブ酸系化合物であることがより好ましい。 As shown in FIG. 1, the piezoelectric thin film element 1 has a piezoelectric thin film 4. The piezoelectric thin film 4 contains an alkali niobic acid compound. The piezoelectric thin film 4 is preferably made of a material mainly composed of an alkali niobic acid compound. More preferably, the alkali niobate compound is an alkali niobate compound having a perovskite structure.
　また、アルカリニオブ酸系化合物は、カリウム、ナトリウム及びニオブを含むニオブ酸カリウムナトリウム系化合物であることが好ましい。ニオブ酸カリウムナトリウム系化合物としては、例えば下記一般式（１）で表される化合物が挙げられる。 Further, the alkali niobate compound is preferably a potassium sodium niobate compound containing potassium, sodium and niobium. Examples of the potassium sodium niobate compound include compounds represented by the following general formula (1).
　（Ｋ１－ａ－ｂ／２Ｎａａ－ｂ／２Ａｂ）（Ｎｂ１－ｃＢｃ）Ｏ３　　（１）
　一般式（１）において、Ａは、Ｌｉ，Ａｇ，Ｃａ，Ｓｒ，Ｂｉ及びＧｄからなる群から選択された少なくとも１種の元素である。Ｂは、Ｔａ，Ｚｒ，Ｔｉ，Ａｌ，Ｓｃ及びＨｆからなる群から選択された少なくとも１種の元素である。ａ、ｂ及びｃは、０＜ａ≦０．９、０≦ｂ≦０．３、０≦ａ＋ｂ≦０．９、０≦ｃ≦０．３の条件を満たす数である。 (K 1-a-b / 2 Na a-b / 2 A b) (Nb 1-c B c) O 3 (1)
In the general formula (1), A is at least one element selected from the group consisting of Li, Ag, Ca, Sr, Bi, and Gd. B is at least one element selected from the group consisting of Ta, Zr, Ti, Al, Sc and Hf. a, b, and c are numbers satisfying the conditions of 0 <a ≦ 0.9, 0 ≦ b ≦ 0.3, 0 ≦ a + b ≦ 0.9, and 0 ≦ c ≦ 0.3.
　圧電薄膜４の厚みは、通常１μｍ～３μｍ程度であり、２μｍ～３μｍ程度であることが好ましい。 The thickness of the piezoelectric thin film 4 is usually about 1 μm to 3 μm, and preferably about 2 μm to 3 μm.
　圧電薄膜４の第１の表面４ａには、第１の電極３が設けられている。具体的には、圧電薄膜４の第１の表面４ａと当接するように、第１の電極３が設けられている。第１の電極３は下部電極である。第１の電極３は、圧電薄膜素子１の剛性を高める支持層としての役割も有する。第１の電極３は、例えばインゴットを切削及び研磨することで形成することができるし、スパッタリング法や蒸着法などの成膜方法によっても形成することができる。 The first electrode 3 is provided on the first surface 4 a of the piezoelectric thin film 4. Specifically, the first electrode 3 is provided so as to be in contact with the first surface 4 a of the piezoelectric thin film 4. The first electrode 3 is a lower electrode. The first electrode 3 also serves as a support layer that increases the rigidity of the piezoelectric thin film element 1. The first electrode 3 can be formed, for example, by cutting and polishing an ingot, or can be formed by a film forming method such as a sputtering method or a vapor deposition method.
　第１の電極３はシリコンからなる。具体的には、第１の電極３を構成するシリコンは、低抵抗シリコンである。低抵抗シリコンは、ヒ素やリンなどがシリコンにドープされ、ピュアなシリコンよりも電気抵抗が低くなったものである。第１の電極３を構成する低抵抗シリコンの抵抗率は、１０－３Ωｃｍ以下であることが好ましい。第１の電極３においては、圧電薄膜４側の表層がシリコンにより構成されていればよく、他の部分は、他の材料により構成されていてもよい。他の材料としては、例えば、ＳｉＯ２やＳｉＮなどのシリコン系化合物、Ｐｔ，Ａｕ，Ａｇ，Ｒｕ，Ｉｒ，Ｃｕ，Ｔｉ，Ａｌなどの金属、これらの金属のうち少なくとも１種を主成分とする合金などが挙げられる。 The first electrode 3 is made of silicon. Specifically, the silicon constituting the first electrode 3 is low resistance silicon. Low-resistance silicon is obtained by doping silicon with arsenic, phosphorus, or the like and having an electric resistance lower than that of pure silicon. The resistivity of the low-resistance silicon constituting the first electrode 3 is preferably 10 −3 Ωcm or less. In the 1st electrode 3, the surface layer by the side of the piezoelectric thin film 4 should just be comprised with the silicon | silicone, and the other part may be comprised with the other material. Examples of other materials include silicon compounds such as SiO 2 and SiN, metals such as Pt, Au, Ag, Ru, Ir, Cu, Ti, and Al, and at least one of these metals as a main component. An alloy etc. are mentioned.
　第１の電極３の厚みは、通常１μｍ～８００μｍ程度であり、支持層としての役割を考慮すると５μｍ以上であることが好ましい。 The thickness of the first electrode 3 is usually about 1 μm to 800 μm, and is preferably 5 μm or more in consideration of the role as a support layer.
　圧電薄膜４の第２の表面４ｂには、第２の電極５が設けられている。具体的には、圧電薄膜４の第２の表面４ｂと当接するように、第２の電極５が設けられている。第２の電極５は上部電極である。第２の電極５は、例えばスパッタリング法や蒸着法などの成膜方法により形成することができる。 A second electrode 5 is provided on the second surface 4 b of the piezoelectric thin film 4. Specifically, the second electrode 5 is provided so as to contact the second surface 4 b of the piezoelectric thin film 4. The second electrode 5 is an upper electrode. The second electrode 5 can be formed by a film forming method such as a sputtering method or a vapor deposition method.
　第２の電極５は、低抵抗シリコン、Ｐｔ，Ａｕ，Ａｇ、Ｒｕ，Ｉｒ、Ｃｕ、Ｔｉ、Ａｌなどの金属、これらの金属のうち少なくとも１種を主成分とする合金などからなる。 The second electrode 5 is made of a metal such as low resistance silicon, Pt, Au, Ag, Ru, Ir, Cu, Ti, Al, an alloy mainly containing at least one of these metals.
　第２の電極５の厚みは、通常０．０５μｍ～０．３μｍ程度であり、０．１μｍ～０．２μｍ程度であることが好ましい。 The thickness of the second electrode 5 is usually about 0.05 μm to 0.3 μm, and preferably about 0.1 μm to 0.2 μm.
　上述の通り、例えばＰｔからなる電極を構成するＰｔ層の上にニオブ酸カリウムナトリウムからなる圧電薄膜を形成すると、圧電薄膜素子の製造時や、圧電薄膜素子に温度変化が生じた際に、圧電薄膜にクラックが形成されやすくなる場合がある。 As described above, for example, when a piezoelectric thin film made of potassium sodium niobate is formed on a Pt layer constituting an electrode made of Pt, a piezoelectric film is produced when the piezoelectric thin film element is manufactured or when a temperature change occurs in the piezoelectric thin film element. In some cases, cracks are easily formed in the thin film.
　これに対して、圧電薄膜素子１では、圧電薄膜４の第１の主面４ａに、シリコンからなる第１の電極３が設けられている。このため、圧電薄膜４にクラックが生じにくい。圧電薄膜４にクラックが生じにくくなる理由の詳細は、明らかではないが、シリコンからなる第１の電極３とアルカリニオブ酸系化合物を含む圧電薄膜４との熱膨張係数の差や格子ミスマッチなどの複数の要因により、圧電薄膜４にかかる応力が緩和されていることによるものと考えられる。 On the other hand, in the piezoelectric thin film element 1, the first electrode 3 made of silicon is provided on the first main surface 4 a of the piezoelectric thin film 4. For this reason, cracks are unlikely to occur in the piezoelectric thin film 4. Although details of the reason why cracks are less likely to occur in the piezoelectric thin film 4 are not clear, such as differences in thermal expansion coefficient and lattice mismatch between the first electrode 3 made of silicon and the piezoelectric thin film 4 containing an alkali niobate compound. It is considered that the stress applied to the piezoelectric thin film 4 is relaxed due to a plurality of factors.
　圧電薄膜素子１は、例えば、次のようにして製造することができる。まず、スパッタリング法、蒸着法などの成膜方法などにより、シリコンからなる第１の電極３を形成する。次に、第１の電極３の上に、スパッタリング法、蒸着法などの成膜方法などにより、ニオブ酸カリウムナトリウム系化合物からなる圧電薄膜４を形成する。例えば、圧電薄膜４を構成するニオブ酸カリウムナトリウム系化合物が、上記一般式（１）で表される化合物である場合、圧電薄膜４は、例えば高周波スパッタリング法により形成される。このとき、圧電薄膜４は、第１の電極３の温度が４００℃～７００℃程度、Ｏ２の分圧／（Ａｒの分圧＋Ｏ２の分圧）＝０．０５～０．５、スパッタ圧力が０．３Ｐａ～１．５Ｐａ程度となる条件で、高周波スパッタリング法により形成されることが好ましい。次に、圧電薄膜４の上に、スパッタリング法や蒸着法などの成膜方法により、第２の電極５を形成する。第２の電極５を形成する前または形成した後に、高速熱処理装置（ＲＴＡ装置：Ｒａｐｉｄ　Ｔｈｅｒｍａｌ　Ａｎｎｅａｌｉｎｇ装置）などによって圧電薄膜４をアニール処理してもよい。以上のようにして、圧電薄膜素子１が得られる。 The piezoelectric thin film element 1 can be manufactured as follows, for example. First, the first electrode 3 made of silicon is formed by a film forming method such as a sputtering method or an evaporation method. Next, the piezoelectric thin film 4 made of a potassium sodium niobate compound is formed on the first electrode 3 by a film forming method such as sputtering or vapor deposition. For example, when the potassium sodium niobate compound constituting the piezoelectric thin film 4 is a compound represented by the general formula (1), the piezoelectric thin film 4 is formed by, for example, a high frequency sputtering method. At this time, the piezoelectric thin film 4 has a temperature of the first electrode 3 of about 400 ° C. to 700 ° C., O 2 partial pressure / (Ar partial pressure + O 2 partial pressure) = 0.05 to 0.5, sputtering. It is preferably formed by a high-frequency sputtering method under conditions where the pressure is about 0.3 Pa to 1.5 Pa. Next, the second electrode 5 is formed on the piezoelectric thin film 4 by a film forming method such as sputtering or vapor deposition. Before or after the second electrode 5 is formed, the piezoelectric thin film 4 may be annealed by a rapid thermal processing apparatus (RTA apparatus: Rapid Thermal Annealing apparatus) or the like. The piezoelectric thin film element 1 is obtained as described above.
　（第２の実施形態）
　図２は、本発明の第２の実施形態に係る圧電薄膜素子１の略図的断面図である。図２に示されるように、本実施形態において、圧電薄膜素子１は、支持層２を有する。具体的には、圧電薄膜素子１において、第１の電極３は、支持層２の上に設けられている。圧電薄膜素子１が支持層２を有することにより、圧電薄膜素子１の剛性が高められている。支持層２を構成する材料は特に限定されない。支持層２を構成する材料としては、例えばシリコン、低温焼成セラミックス、Ａｌ２Ｏ３などの絶縁性セラミックス、ＬｉＴａＯ３，ＬｉＮｂＯ３，水晶などの圧電単結品、ＳｉＣ，ＧａＡｓ，ＧａＮなどの半導体、ガラスなどが挙げられる。支持層２がシリコンからなる場合、支持層２は、ヒ素やリンなどがドープされていて、抵抗率が１０－２Ωｃｍ以下であるシリコンにより構成されていることが好ましい。 (Second Embodiment)
FIG. 2 is a schematic cross-sectional view of a piezoelectric thin film element 1 according to the second embodiment of the present invention. As shown in FIG. 2, in the present embodiment, the piezoelectric thin film element 1 has a support layer 2. Specifically, in the piezoelectric thin film element 1, the first electrode 3 is provided on the support layer 2. Since the piezoelectric thin film element 1 has the support layer 2, the rigidity of the piezoelectric thin film element 1 is enhanced. The material which comprises the support layer 2 is not specifically limited. Examples of the material constituting the support layer 2 include silicon, low-temperature fired ceramics, insulating ceramics such as Al 2 O 3 , piezoelectric single-pieces such as LiTaO 3 , LiNbO 3 , and quartz, semiconductors such as SiC, GaAs, and GaN, Glass etc. are mentioned. When the support layer 2 is made of silicon, the support layer 2 is preferably made of silicon doped with arsenic or phosphorus and having a resistivity of 10 −2 Ωcm or less.
　本実施形態においては、例えば、シリコン基板などの一方側主面の上から、０．０１～０．１μｍ程度の深さまでヒ素やリンなどをドープし、低抵抗化された表層を第１の電極３とし、他の部分を支持層２としてもよい。支持層２の厚みは、通常５０μｍ～８００μｍ程度である。 In this embodiment, for example, arsenic or phosphorus is doped to a depth of about 0.01 to 0.1 μm from one main surface of a silicon substrate or the like, and the surface layer with a reduced resistance is used as the first electrode. 3 and other portions may be the support layer 2. The thickness of the support layer 2 is usually about 50 μm to 800 μm.
　（第３の実施形態）
　図３は、本発明の第３の実施形態に係る圧電薄膜素子１の略図的断面図である。図３に示されるように、本実施形態においては、圧電薄膜４と第１の電極３との間にシード層６が設けられている。圧電薄膜４と第１の電極３との間に、シード層６が設けられていることにより、圧電薄膜４を構成するアルカリニオブ酸系化合物の結晶の配向性を高めることができる。このため、圧電薄膜４にクラックが形成されることをより効果的に抑制し得る。シード層６は、ＬａＮｉＯ３，ＬａＳｃＯ３，ＬａＧａＯ３，ＫＮｂＯ３，ＮａＮｂＯ３，ＳｒＲｕＯ３などのペロブスカイト型酸化物、ＺｎＯ，ＴｉＯ２，ＣｅＯ２などの酸化物、ＡｌＮ，ＺｒＮなどの窒化物からなる群から選択された少なくとも１種により構成されることが好ましく、ＬａＮｉＯ３により構成されることがより好ましい。なお、圧電薄膜４と同じ材料を３００℃程度の温度で成膜して作製された膜をシード層６としてもよい。 (Third embodiment)
FIG. 3 is a schematic cross-sectional view of a piezoelectric thin film element 1 according to a third embodiment of the present invention. As shown in FIG. 3, in this embodiment, a seed layer 6 is provided between the piezoelectric thin film 4 and the first electrode 3. By providing the seed layer 6 between the piezoelectric thin film 4 and the first electrode 3, the crystal orientation of the alkali niobate compound constituting the piezoelectric thin film 4 can be enhanced. For this reason, it can suppress more effectively that a crack is formed in the piezoelectric thin film 4. The seed layer 6 is made of a LaNiO 3, LaScO 3, LaGaO 3 , KNbO 3, NaNbO 3, perovskite oxide such as SrRuO 3, ZnO, TiO 2, oxides such as CeO 2, AlN, nitrides such as ZrN It is preferably composed of at least one selected from the group, and more preferably composed of LaNiO 3 . Note that a film formed by forming the same material as the piezoelectric thin film 4 at a temperature of about 300 ° C. may be used as the seed layer 6.
　シード層６の厚みが薄すぎると、アルカリニオブ酸系化合物の結晶の配向性を高める効果が小さくなる場合がある。また、シード層６の厚みが厚すぎると、圧電薄膜４に電圧が印加されにくくなったり、厚みのばらつきが生じてシード層６の表面の平坦性が悪くなる場合がある。よって、シード層６の厚みは、１０ｎｍ以上であることが好ましく、２００ｎｍ以下であることが好ましい。 If the thickness of the seed layer 6 is too thin, the effect of increasing the crystal orientation of the alkali niobate compound may be reduced. On the other hand, if the seed layer 6 is too thick, it may be difficult to apply a voltage to the piezoelectric thin film 4 or the thickness may vary, resulting in poor surface flatness of the seed layer 6. Therefore, the thickness of the seed layer 6 is preferably 10 nm or more, and preferably 200 nm or less.
　以下、本発明について、具体的な実施例に基づいて、さらに詳細に説明する。本発明は、以下の実施例に何ら限定されるものではなく、その要旨を変更しない範囲において適宜変更して実施することが可能である。 Hereinafter, the present invention will be described in more detail based on specific examples. The present invention is not limited to the following examples, and can be implemented with appropriate modifications without departing from the scope of the invention.
　（実施例１）
　厚みが５００μｍであるシリコン基板を用意し、シリコン基板の一方側主面の上から０．０１～０．１μｍ程度の深さまでヒ素をドープすることによって、低抵抗化された表層が第１の電極３を構成し、他の部分が支持層２を構成する、低抵抗シリコン基板を形成した。次に、第１の電極３の上に、第１の電極３の温度が６００℃、Ｏ２の分圧／（Ａｒの分圧＋Ｏ２の分圧）＝０．１、スパッタ圧力が０．３Ｐａである条件で、組成が（Ｋ０．５，Ｎａ０．５）ＮｂＯ３であるターゲットを用いたスパッタリング法により、厚みが２μｍであり、ニオブ酸カリウムナトリウム系化合物からなる圧電薄膜４を形成した。 (Example 1)
A silicon substrate having a thickness of 500 μm is prepared, and arsenic is doped to a depth of about 0.01 to 0.1 μm from one main surface of the silicon substrate, so that the surface layer whose resistance has been reduced is the first electrode. 3 and a low resistance silicon substrate in which the other part constitutes the support layer 2 was formed. Next, on the first electrode 3, the temperature of the first electrode 3 is 600 ° C., the partial pressure of O 2 / (the partial pressure of Ar + the partial pressure of O 2 ) = 0.1, and the sputtering pressure is 0.1. in a a condition 3 Pa, formation composition (K 0.5, Na 0.5) by a sputtering method using a target which is NbO 3, a thickness of 2 [mu] m, the piezoelectric thin film 4 consisting of sodium potassium niobate compound did.
　実施例１で形成した圧電薄膜４の表面のレーザー顕微鏡像（一辺が１２５μｍの視野内）を図４に示す。 FIG. 4 shows a laser microscope image (within a field of view of 125 μm on one side) of the surface of the piezoelectric thin film 4 formed in Example 1.
　（実施例２）
　厚みが５００μｍであるシリコン基板を用意し、シリコン基板の一方側主面の上から０．０１～０．１μｍ程度の深さまでヒ素をドープすることによって、低抵抗化された表層が第１の電極３を構成し、他の部分が支持層２を構成する、低抵抗シリコン基板を形成した。次に、第１の電極３の上に、第１の電極３の温度が３００℃、Ｏ２の分圧／（Ａｒの分圧＋Ｏ２の分圧）＝０．９、スパッタ圧力が０．２７Ｐａである条件で、組成がＬａＮｉＯ３であるターゲットを用いたスパッタリング法により、厚みが３０ｎｍであり、ＬａＮｉＯ３からなるシード層６を形成した。そして、シード層６の上に、第１の電極３の温度が６００℃、Ｏ２の分圧／（Ａｒの分圧＋Ｏ２の分圧）＝０．１、スパッタ圧力が０．３Ｐａである条件で、（Ｋ０．５，Ｎａ０．５）ＮｂＯ３の組成のターゲットを用いたスパッタリング法により、厚みが２μｍであり、ニオブ酸カリウムナトリウム系化合物からなる圧電薄膜４を形成した。 (Example 2)
A silicon substrate having a thickness of 500 μm is prepared, and arsenic is doped to a depth of about 0.01 to 0.1 μm from one main surface of the silicon substrate, so that the surface layer whose resistance has been reduced is the first electrode. 3 and a low resistance silicon substrate in which the other part constitutes the support layer 2 was formed. Next, on the first electrode 3, the temperature of the first electrode 3 is 300 ° C., the partial pressure of O 2 / (the partial pressure of Ar + the partial pressure of O 2 ) = 0.9, and the sputtering pressure is 0.1. A seed layer 6 of LaNiO 3 having a thickness of 30 nm was formed by sputtering using a target having a composition of LaNiO 3 under the condition of 27 Pa. On the seed layer 6, the temperature of the first electrode 3 is 600 ° C., the partial pressure of O 2 / (the partial pressure of Ar + the partial pressure of O 2 ) = 0.1, and the sputtering pressure is 0.3 Pa. A piezoelectric thin film 4 having a thickness of 2 μm and made of a potassium sodium niobate compound was formed by sputtering using a target having a composition of (K 0.5 , Na 0.5 ) NbO 3 under the conditions.
　実施例２で形成した圧電薄膜４の表面のレーザー顕微鏡像（一辺が１２５μｍの視野内）を図５に示す。 FIG. 5 shows a laser microscope image (within a field of view of 125 μm on one side) of the surface of the piezoelectric thin film 4 formed in Example 2.
　（比較例１）
　支持層として、厚みが３００μｍであり、厚みが７００ｎｍの熱酸化膜が表面に形成されている、シリコン基板を用意した。シリコン基板の上に、スパッタリング法により、厚みが２０ｎｍであり、ＴｉＯ２からなる密着層を形成した。密着層の上に、スパッタリング法により、シリコン基板の温度が４３０℃、Ａｒ雰囲気、スパッタ圧力が０．４Ｐａである条件で、厚みが１００ｎｍであり、Ｐｔからなる第１の電極を形成した。次に、第１の電極の上に、シリコン基板の温度が３００℃、Ｏ２の分圧／（Ａｒの分圧＋Ｏ２の分圧）＝０．９、スパッタ圧力が０．２７Ｐａである条件で、組成がＬａＮｉＯ３であるターゲットを用いたスパッタリング法により、厚みが３０ｎｍであり、ＬａＮｉＯ３からなるシード層を形成した。そして、シード層の上に、シリコン基板の温度が６００℃、Ｏ２の分圧／（Ａｒの分圧＋Ｏ２の分圧）＝０．１、スパッタ圧力が０．３Ｐａである条件で、（Ｋ０．５，Ｎａ０．５）ＮｂＯ３の組成のターゲットを用いたスパッタリング法により、厚みが２μｍであり、ニオブ酸カリウムナトリウム系化合物からなる圧電薄膜を形成した。 (Comparative Example 1)
As the support layer, a silicon substrate having a thickness of 300 μm and a thermal oxide film having a thickness of 700 nm formed on the surface was prepared. An adhesion layer made of TiO 2 having a thickness of 20 nm was formed on the silicon substrate by sputtering. A first electrode made of Pt and having a thickness of 100 nm was formed on the adhesion layer by sputtering under the conditions that the temperature of the silicon substrate was 430 ° C., the Ar atmosphere, and the sputtering pressure was 0.4 Pa. Next, on the first electrode, the temperature of the silicon substrate is 300 ° C., the partial pressure of O 2 / (the partial pressure of Ar + the partial pressure of O 2 ) = 0.9, and the sputtering pressure is 0.27 Pa. Then, a seed layer having a thickness of 30 nm and made of LaNiO 3 was formed by a sputtering method using a target having a composition of LaNiO 3 . Then, on the seed layer, the temperature of the silicon substrate is 600 ° C., the partial pressure of O 2 / (the partial pressure of Ar + the partial pressure of O 2 ) = 0.1, and the sputtering pressure is 0.3 Pa ( A piezoelectric thin film having a thickness of 2 μm and made of a potassium sodium niobate compound was formed by sputtering using a target having a composition of K 0.5 , Na 0.5 ) NbO 3 .
　比較例１で形成した圧電薄膜の表面のレーザー顕微鏡像（一辺が１２５μｍの視野内）を図６に示す。 FIG. 6 shows a laser microscope image (within a field of view of 125 μm on one side) of the surface of the piezoelectric thin film formed in Comparative Example 1.
　（比較例２）
　支持層として、厚みが３００μｍであり、厚みが７００ｎｍの熱酸化膜が表面に形成されている、シリコン基板を用意した。シリコン基板の上に、スパッタリング法により、厚みが２０ｎｍであり、ＴｉＯ２からなる密着層を形成した。密着層の上に、スパッタリング法により、シリコン基板の温度が４３０℃、Ａｒ雰囲気、スパッタ圧力が０．４Ｐａである条件で、厚みが１００ｎｍであり、Ｐｔからなる第１の電極を形成した。次に、第１の電極の上に、シリコン基板の温度が６００℃、Ｏ２の分圧／（Ａｒの分圧＋Ｏ２の分圧）＝０．１、スパッタ圧力が０．３Ｐａである条件で、（Ｋ０．５，Ｎａ０．５）ＮｂＯ３の組成のターゲットを用いたスパッタリング法により、厚みが２μｍであり、ニオブ酸カリウムナトリウム系化合物からなる圧電薄膜を形成した。 (Comparative Example 2)
As the support layer, a silicon substrate having a thickness of 300 μm and a thermal oxide film having a thickness of 700 nm formed on the surface was prepared. An adhesion layer made of TiO 2 having a thickness of 20 nm was formed on the silicon substrate by sputtering. A first electrode made of Pt and having a thickness of 100 nm was formed on the adhesion layer by sputtering under the conditions that the temperature of the silicon substrate was 430 ° C., the Ar atmosphere, and the sputtering pressure was 0.4 Pa. Next, on the first electrode, the temperature of the silicon substrate is 600 ° C., the partial pressure of O 2 / (Ar partial pressure + O 2 partial pressure) = 0.1, and the sputtering pressure is 0.3 Pa. Thus, a piezoelectric thin film made of a potassium sodium niobate compound and having a thickness of 2 μm was formed by sputtering using a target having a composition of (K 0.5 , Na 0.5 ) NbO 3 .
　比較例２で得られた圧電薄膜の表面をレーザー顕微鏡で観察したところ、圧電薄膜の表面構造が粗く、上部電極を形成するには適しておらず、圧電薄膜素子に求められる機能を実現することが困難であることが分かった。 When the surface of the piezoelectric thin film obtained in Comparative Example 2 was observed with a laser microscope, the surface structure of the piezoelectric thin film was rough and not suitable for forming the upper electrode, and the function required for the piezoelectric thin film element was realized. Proved difficult.
１…圧電薄膜素子
２…支持層
３…第１の電極
４…圧電薄膜
４ａ…圧電薄膜の第１の表面
４ｂ…圧電薄膜の第２の表面
５…第２の電極
６…シード層 DESCRIPTION OF SYMBOLS 1 ... Piezoelectric thin film element 2 ... Support layer 3 ... 1st electrode 4 ... Piezoelectric thin film 4a ... 1st surface 4b of a piezoelectric thin film ... 2nd surface 5 of a piezoelectric thin film ... 2nd electrode 6 ... Seed layer

Claims (4)

  1. 　アルカリニオブ酸系化合物を含む圧電薄膜と、
    　前記圧電薄膜の一方側主面に設けられた第１の電極と、
    　前記圧電薄膜の他方側主面に設けられた第２の電極と、
    を備え、
    　前記第１の電極が、シリコンからなる、圧電薄膜素子。     A piezoelectric thin film containing an alkali niobate compound;
    A first electrode provided on one main surface of the piezoelectric thin film;
    A second electrode provided on the other principal surface of the piezoelectric thin film;
    With
    A piezoelectric thin film element in which the first electrode is made of silicon.
  2. 　前記圧電薄膜と、前記第１の電極との間には、シード層が設けられている、請求項１に記載の圧電薄膜素子。 The piezoelectric thin film element according to claim 1, wherein a seed layer is provided between the piezoelectric thin film and the first electrode.
  3. 　前記シード層が、ＬａＮｉＯ３，ＬａＳｃＯ３，ＬａＧａＯ３，ＫＮｂＯ３，ＮａＮｂＯ３，ＳｒＲｕＯ３などのペロブスカイト型酸化物、ＺｎＯ，ＴｉＯ２，ＣｅＯ２などの酸化物、ＡｌＮ，ＺｒＮなどの窒化物からなる群から選択された少なくとも１種により構成されている、請求項１または２に記載の圧電薄膜素子。 The seed layer is made of LaNiO 3, LaScO 3, LaGaO 3 , KNbO 3, NaNbO 3, perovskite oxide such as SrRuO 3, ZnO, TiO 2, oxides such as CeO 2, AlN, nitrides such as ZrN The piezoelectric thin film element according to claim 1 or 2, comprising at least one selected from the group.
  4. 　シリコンからなる電極の上に、アルカリニオブ酸系化合物を含む圧電薄膜を形成する、圧電薄膜素子の製造方法。 A method for manufacturing a piezoelectric thin film element, comprising forming a piezoelectric thin film containing an alkali niobic acid compound on an electrode made of silicon.
PCT/JP2013/065462 2012-07-02 2013-06-04 Piezoelectric thin film element and method for manufacturing same WO2014007015A1 (en)

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