CN102823007A - Piezoelectric thin-film element, process for producing same, and piezoelectric thin-film device - Google Patents
Piezoelectric thin-film element, process for producing same, and piezoelectric thin-film device Download PDFInfo
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- CN102823007A CN102823007A CN2010800657795A CN201080065779A CN102823007A CN 102823007 A CN102823007 A CN 102823007A CN 2010800657795 A CN2010800657795 A CN 2010800657795A CN 201080065779 A CN201080065779 A CN 201080065779A CN 102823007 A CN102823007 A CN 102823007A
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- 239000000203 mixture Substances 0.000 claims description 65
- 238000010276 construction Methods 0.000 claims description 11
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- 239000000956 alloy Substances 0.000 claims description 8
- 239000002245 particle Substances 0.000 claims description 5
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- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 abstract 1
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- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 3
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- PSVBHJWAIYBPRO-UHFFFAOYSA-N lithium;niobium(5+);oxygen(2-) Chemical compound [Li+].[O-2].[O-2].[O-2].[Nb+5] PSVBHJWAIYBPRO-UHFFFAOYSA-N 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
- C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
- C23C14/08—Oxides
- C23C14/088—Oxides of the type ABO3 with A representing alkali, alkaline earth metal or Pb and B representing a refractory or rare earth metal
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
- C30B23/02—Epitaxial-layer growth
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- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/16—Oxides
- C30B29/22—Complex oxides
- C30B29/30—Niobates; Vanadates; Tantalates
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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 devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02015—Characteristics of piezoelectric layers, e.g. cutting angles
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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 devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02007—Details of bulk acoustic wave devices
- H03H9/02086—Means for compensation or elimination of undesirable effects
- H03H9/02094—Means for compensation or elimination of undesirable effects of adherence
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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 devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02543—Characteristics of substrate, e.g. cutting angles
- H03H9/02574—Characteristics of substrate, e.g. cutting angles of combined substrates, multilayered substrates, piezoelectrical layers on not-piezoelectrical substrate
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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
- H10N30/01—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
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- H—ELECTRICITY
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- 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
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- H—ELECTRICITY
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- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
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Abstract
Disclosed is a piezoelectric thin-film element which comprises a substrate and, disposed thereon, at least a lower electrode, a piezoelectric thin film represented by the general formula (NaxKyLiz)NbO3 (0=x=1, 0=y=1, 0=z=0.2, and x+y+z=1), and an upper electrode, characterized in that the piezoelectric thin film has a crystal structure constituted of a quasi-cubic, tetragonal, or orthorhombic system or has a state in which at least one of those crystal systems is coexistent, that the crystal grains have been oriented preferentially along up to two specific crystallographic axes among those axes, and that with respect to the ratio between (001) components and (111) components, as the oriented crystallographic components, the proportion by volume of the (001) components is 60-100% and the proportion by volume of the (111) components is 0-40%, when the sum of both is taken as 100%.
Description
Technical field
The present invention relates to use the piezoelectric thin film device and the piezoelectric membrane device of lithium potassium niobate sodium film etc.
Background technology
According to various purposes piezoelectrics are processed into various piezoelectric devices, especially are widely used as through applying that voltage produces the driver of strain or producing the functional electric subassembly of the transducer etc. of voltage by the strain of device.As the piezoelectrics that are used for driver or transducer, the lead with excellent piezoelectric properties that has been widely used so far is dielectric, especially uses the Pb (Zr that is called as PZT
1-xTi
x) O
3The Ca-Ti ore type ferroelectric of system, piezoelectrics normally form through the oxidesintering that will contain various elements.In addition,, hope the lead-free piezoelectrics of exploitation, developing lithium potassium niobate sodium (general formula: (Na in recent years because of misgivings to environment
xK
yLi
z) NbO
3(0＜x＜1,0＜y＜1,0＜z＜1, x+y+z=1) (below be called LKNN) etc.Because this LKNN has the piezoelectric property that matches in excellence or beauty in PZT, therefore by the strong candidate of expectation as non-plumbous piezoelectric.In addition, LKNN comprises potassium-sodium niobate (KNN) film.
On the other hand, along with the small-sized and high performance development of various electronic components, also require consumingly now piezoelectric device miniaturization and high performance.Yet, through being that piezoelectric, especially its thickness that the manufacturing approach at center is made reach below the 10 μ m when thick with the sintering process of method for making in the past, approach the size of the crystal grain of constituent material, can't ignore the influence of size.Thereby deviation or deterioration that characteristic the occurred significant problem that becomes.For fear of this problem, Recent study applied film technology etc. replace sintering process to form the method for piezoelectric membrane.
Recently, the actual pzt thin film that will use the RF sputtering method to form is used as the gyro sensor (for example with reference to patent documentation 1, non-patent literature 1) of high-precision thin and tall fast ink jet-print head with driver or small-sized low price.In addition, also propose have use not use the piezoelectric thin film device (for example with reference to patent documentation 2) of plumbous LKNN piezoelectric membrane.
The prior art document
Patent documentation
Patent documentation 1: japanese kokai publication hei 10-286953 communique
Patent documentation 2: TOHKEMY 2007-19302 communique
Non-patent literature
Patent Document 1: Nakamura Xi Liang editor piezoelectric material's high performance and cutting-edge application technology (Piezoelectric Materials by high performance と apex Applied Technology) (Science & technology (thermal イ Oh nn su & Te black Bruno ro ji have), published in 2007)
Summary of the invention
The problem that invention will solve
Through forming non-plumbous piezoelectric membrane, can bear the gyro sensor of little high-precision thin and tall fast ink-jet printer by production environment with shower nozzle or small-sized low price as piezoelectric membrane.As concrete candidate, carrying out the basic research of the filmization of LKNN.
Yet in prior art (for example patent documentation 2), orientation of piezoelectric membrane etc. is not at length studied, can't stably be realized to show the piezoelectric thin film device of high piezoelectric constant.
The object of the present invention is to provide piezoelectric thin film device and the piezoelectric membrane device of seeking to improve piezoelectric property.
The scheme that is used to deal with problems
According to a kind of mode of the present invention, a kind of piezoelectric thin film device is provided, its on substrate, dispose lower electrode at least, with general formula (Na
xK
yLi
z) NbO
3The piezoelectric membrane of (0≤x≤1,0≤y≤1,0≤z≤0.2, x+y+z=1) expression and the range upon range of body of piezoelectric membrane of upper electrode; Wherein, Said piezoelectric membrane has accurate cube of crystalline substance, regular crystal or orthorhombic crystal structure; Perhaps be the state of at least a coexistence in these said crystal structures, some the specific axis preferred orientation in their crystallographic axis below 2, and as the composition of the crystallographic axis of said orientation; In the ratio of (001) composition and (111) composition; With the two add up to 100% o'clock, the volume fraction of (001) composition is in the scope more than 60% and below 100%, and the volume fraction of (111) composition is in the scope more than 0% and below 40%.
At this moment, the volume fraction of especially preferred (001) composition is in the higher scope more than 70% and below 100% of degree of crystallinity, and the volume fraction of (111) composition is in the scope more than 0% and below 30%.
In addition, said piezoelectric membrane is preferably the state of said (001) composition and the coexistence of said (111) composition, and the volume fraction of (111) composition is more preferably greater than 1%.
In addition, preferred said piezoelectric membrane has the aggregate structure that the particle by column structure constitutes.
In addition, the part of said piezoelectric membrane also can contain ABO
3Crystal layer, ABO
3Amorphous layer or be mixed with ABO
3Crystal and in the non-crystal mixed layer any.
Wherein, A is the element more than a kind that is selected among Li, Na, K, La, Sr, Nd, Ba and the Bi, and B is the element more than a kind that is selected among Zr, Ti, Mn, Mg, Nb, Sn, Sb, Ta and the In, and O is an oxygen.
In addition, said piezoelectric membrane can have strain in the direction parallel with real estate.
In addition, said strain can be the strain of tensile stress state on the direction parallel with real estate or the strain of compressing stress state.In addition, said piezoelectric membrane can be for there not being the no strain regime of internal stress yet.
In addition, said piezoelectric membrane also can have uneven strain with vertical direction or parallel direction or two directions of real estate.
In addition, lower electrode layer be preferably Pt or with Pt be main component alloy, or comprise the electrode layer of stepped construction that these are the electrode layer of main component with Pt.
In addition, as lower electrode layer, also can be comprise Ru, Ir, Sn, In and oxide thereof, with piezoelectric membrane in the electrode layer of stepped construction of layer of the compound that forms of contained element.
In addition, top electrode layer be Pt or with Pt be main component alloy, or comprise the electrode layer of stepped construction that these are the electrode layer of main component with Pt.
In addition, as top electrode layer, also can be comprise Ru, Ir, Sn, In and oxide thereof, with piezoelectric membrane in the electrode layer of stepped construction of electrode layer of the compound that forms of contained element.
In addition, relevant as said lower electrode layer with its crystal orientation property, be preferably at the individual layer of the orientation preferentially orientation vertical or the electrode layer of stepped construction with substrate surface.
In addition, said substrate can be for being selected from Si substrate, MgO substrate, zno-based plate, SrTiO
3Substrate, SrRuO
31 kind of substrate in substrate, glass substrate, quartz glass substrate, GaAs substrate, GaN substrate, sapphire substrate, Ge substrate and the stainless steel substrate.Preferred especially said substrate is the Si substrate.
According to alternate manner of the present invention, a kind of piezoelectric thin film device is provided, it is for to dispose on substrate with general formula (Na
xK
yLi
z) NbO
3The range upon range of body of piezoelectric membrane of the piezoelectric membrane of (0≤x≤1,0≤y≤1,0≤z≤0.2, x+y+z=1) expression,
Wherein, Said piezoelectric membrane has accurate cube of crystalline substance, regular crystal or orthorhombic crystal structure; Perhaps be the state of at least a coexistence in these said crystal structures, some the specific axis preferred orientation in their crystallographic axis below 2 is coexisting state as (001) composition of the composition of the crystallographic axis of said preferred orientation with (111) composition; And in the ratio of (001) composition and (111) composition; With the two add up to 100% o'clock, the volume fraction of (001) composition greater than 60% and less than 100% scope in, the volume fraction of (111) composition is in less than 40% scope.
In addition, between said substrate and said piezoelectric membrane, can have basalis.Basalis can use LaNiO
3, NaNbO
3, also can use Pt film at (111) preferred orientation.
In addition, according to alternate manner of the present invention, the piezoelectric membrane device that possesses above-mentioned piezoelectric thin film device and voltage applying unit or voltage detection unit is provided.
The effect of invention
Adopt the present invention, can provide piezoelectric property excellent piezoelectric thin film device and piezoelectric membrane device.
Description of drawings
Fig. 1 is the sectional view of the piezoelectric thin film device of the piezoelectric membrane of use embodiments of the invention 1.
Fig. 2 is the figure of an example of the X-ray diffractogram of 2 θ/θ scanning of the piezoelectric thin film device of demonstration embodiments of the invention 1.
Fig. 3 is the figure of the crystal structure of the KNN piezoelectric membrane of demonstration embodiments of the invention 1.
Fig. 4 is the experimental configuration figure of the utmost point figure of the KNN piezoelectric membrane of mensuration embodiments of the invention 1.
Fig. 5 is the performance plot of the KNN piezoelectric membrane of embodiments of the invention 1, and is (a) for mensuration result's example of wide-angle reciprocal lattice mapping, (b) routine for the simulation of wide-angle reciprocal lattice mapping.
Fig. 6 is the performance plot of the KNN piezoelectric membrane (KNN-1) of embodiments of the invention 1, (a) is the X ray reflection curve of obtaining along χ direction of principal axis integral and calculating that is caused by (111) and (001) in (110) diffraction for mensuration result's example of using two-dimensional x-ray detector, (b).
Fig. 7 is the performance plot of the KNN piezoelectric membrane (KNN-2) of embodiments of the invention 1; (a), (b) be the X ray reflection curve of obtaining along χ direction of principal axis integral and calculating that causes by (111) and (001) in (110) diffraction for using mensuration result's example of two-dimensional x-ray detector.
Fig. 8 is the performance plot of embodiments of the invention 1, (a) is the axonmetric chart of utmost point figure, (b) for the axonmetric chart of utmost point figure being transformed to the figure of orthogonal coordinates.
Fig. 9 is the utmost point figure of embodiments of the invention 2, (a) with the model of (001) orientation as the utmost point (110) utmost point figure, (b) with the model of (111) orientation as the utmost point (110) utmost point figure.
Figure 10 is the figure of the X-ray diffraction curve characteristic of demonstration embodiments of the invention 2; (a) be the example that the mensuration result of Fig. 6 and X-ray diffraction curve shown in Figure 7 is carried out Fitting Analysis; (b) be the integrated intensity that obtains for Fitting Analysis, considered the analysis result example of the volume fraction of (001) and (111) after the correction coefficient by Figure 10 (a).
Figure 11 is the sectional view of the KNN piezoelectric thin film device of embodiments of the invention 3, (a) is the sketch map that forms the high alignment films of KNN piezoelectric membrane, (b) shows the sketch map of the crystal grain of the high KNN piezoelectric membrane that is orientated with respect to the real estate inclination.
Figure 12 is the film-forming temperature and the graph of a relation that is derived from the integrated intensity of (111) and (001) preferred orientation of the spatter film forming of the KNN piezoelectric membrane of embodiments of the invention 4.
Figure 13 shows in the spatter film forming of KNN piezoelectric membrane of embodiments of the invention 4 with respect to (001) orientation component of film-forming temperature and the variation diagram of (111) orientation component.
Figure 14 shows in the spatter film forming of KNN piezoelectric membrane of embodiments of the invention 4 variation diagram with respect to the internal stress of film-forming temperature.
Figure 15 shows with respect to the real estate of the KNN piezoelectric membrane of (001) and (111) preferred orientation coexistence of embodiments of the invention 4, the crystal grain of each preferred orientation to have the sectional view at certain inclination angle.
Figure 16 in the piezoelectric thin film device of the piezoelectric membrane that uses embodiments of the invention 5, be derived from integrated intensity and the graph of a relation of piezoelectric constant of (111) preferred orientation of piezoelectric membrane.
Figure 17 be in the piezoelectric thin film device of the piezoelectric membrane that uses embodiments of the invention 5, the volume fraction of (111) orientation component of piezoelectric membrane and the graph of a relation of piezoelectric constant.
Figure 18 be in the piezoelectric thin film device of the piezoelectric membrane of the present invention that uses embodiments of the invention 5 to form, the volume fraction of (001) orientation component of piezoelectric membrane and the graph of a relation of piezoelectric constant.
Figure 19 is the concise and to the point pie graph of RF sputter equipment that is used to make the piezoelectric thin film device of the piezoelectric membrane that uses embodiments of the invention 3.
Figure 20 in the substrate that has piezoelectric membrane (wafer) of the piezoelectric membrane that uses embodiments of the invention 5, the volume fraction of (111) orientation component of piezoelectric membrane and the graph of a relation of the piezoelectric constant deviation (%) in the wafer face.
Figure 21 is the concise and to the point pie graph of the piezoelectric membrane device of one embodiment of the present invention.
Figure 22 is the schematic cross-section of the filter of use piezoelectric membrane of the present invention.
Embodiment
The execution mode of the piezoelectric thin film device that the present invention relates to below is described.
[summary of execution mode]
Inventor of the present invention is a piezoelectric membrane to the non-lead at the key position that is positioned at piezoelectric device; Through quantitatively and accurately controlling the crystal orientation property that prior art was not studied, recognize piezoelectric thin film device and the piezo-electric device that to realize showing high piezoelectric constant.
Do not manage and when controlling the crystal orientation property of piezoelectric membrane, can't obtain high piezoelectric constant, and since crystal orientation property to comply with into film location different and different, thereby piezoelectric constant heterogeneity in device.
Adopt execution mode of the present invention; Through suitable selected electrode, piezoelectric membrane etc. as constituent material; Control the membrance casting conditions such as film-forming temperature of piezoelectric membrane simultaneously; With the volume fraction of (001) and (111) composition of the crystallographic axis of the preferred orientation of piezoelectric membrane (composition of crystal orientation property than) separate provision in prescribed limit, thereby can realize piezoelectric thin film device and the manufacturing approach thereof that piezoelectric property is high.
[a kind of basic structure of piezoelectric thin film device]
The piezoelectric thin film device of this execution mode has the stepped construction that is made up of following: substrate; Be formed at the oxide-film on the surface of said substrate; Be formed at the lower electrode layer on the said oxide-film; Be formed at the piezoelectric membrane on the said lower electrode layer; Be formed at the top electrode layer on the said piezoelectric membrane.
This piezoelectric membrane is the ABO with perovskite structure
3The type oxide, it consists of: the A position is the element more than a kind that is selected among Li, Na, K, La, Sr, Nd, Ba and the Bi, and the B position is the element more than a kind that is selected among Zr, Ti, Mn, Mg, Nb, Sn, Sb, Ta and the In, and O is an oxygen.
Said substrate can be enumerated and be selected from Si substrate, MgO substrate, zno-based plate, SrTiO
3Substrate, SrRuO
3Any a kind of substrate in substrate, glass substrate, quartz glass substrate, GaAs substrate, GaN substrate, sapphire substrate, Ge substrate, the stainless steel substrate etc.Especially expectation for price low and industrial on the Si substrate of practical achievement is arranged.
The said oxide-film that forms on the surface of substrate can be enumerated the heat oxide film that forms through thermal oxidation, the Si oxide-film that passes through the formation of CVD (chemical vapour deposition (CVD), Chemical Vapor Deposition) method etc.In addition, also can not form said oxide-film, and at quartz glass (SiO
2), MgO, SrTiO
3, SrRuO
3Directly form lower electrode layers such as Pt electrode on the oxide substrates such as substrate.
It is the electrode layer that constitutes of the alloy of main component that said lower electrode layer is preferably by Pt or with Pt, or comprise the electrode layer of the electrode layer that constitutes that they are cascaded.In addition, preferred said lower electrode layer forms at (111) planar orientation, is between the electrode layer that constitutes of the alloy of main component at substrate and by Pt or with Pt, can be provided for improving the adhesive linkage with the adaptation of substrate.(111) the Pt film of planar orientation plays the effect of basalis for piezoelectric membrane.
Also can be ABO as said piezoelectric membrane
3The type oxide is with potassium-sodium niobate, lithium potassium niobate sodium (below be called LKNN), with general formula (Na
xK
yLi
z) NbO
3The perofskite type oxide of (0≤x≤1,0≤y≤1,0≤z≤0.2, x+y+z=1) expression is the piezoelectric membrane of principal phase.Ta or V of ormal weight etc. also can mix in the LKNN film.Said piezoelectric membrane can use formation such as RF sputtering method, ion beam sputtering or CVD method.Adopt the RF sputtering method in this execution mode.
[according to the crystal orientation control of execution mode]
About the crystal orientation property of LKNN film, in the past less than it at length not being analyzed and being not that benchmark is controlled accurately with it.That is, still indeterminate about the crystal orientation property of this piezoelectric membrane so far: as whether to be random state of orientation; Perhaps, whether only certain 1 in the orientation preferentially vertical orientation with the Si real estate; Or specific axle more than 2 or 2 is with the ratio preferred orientation of which kind of degree etc.In other words; Crystal orientation property about one of factor of the characteristic that determines this piezoelectric membrane; Since be not used to find out minor variations accurately quantitatively, and only make this piezoelectric membrane, so high piezoelectric constant that can't the well reproduced expectation based on evaluation result qualitatively.
Actual in presenting the LKNN film of this (001) preferred orientation sexual state, its piezoelectric property complies with into film location or every production batch is different and different.Its reason is: owing to can not find the slight change of (001) orientation of this piezoelectric membrane; Do not carry out detail analysis for comprising that (001) (110) orientation, (111) orientation and (210) orientation in being oriented in waits in addition, therefore be difficult to strictly control the orientation of above-mentioned each crystal face and make crystal growth.
For example; Input power (Power) during through the increase spatter film forming; Because the impact of Ar ion homenergic particle is driven on the substrate a large amount of sputtering particles by the strong hand along certain orientation, its result has formed the piezoelectric membrane that the polycrystalline particle of bigger inclination is arranged with the normal direction of substrate surface.At this moment; Adopt the known easy X-ray diffraction method that is called as 2 θ/θ scanning, can confirm that crystal orientation property is roughly (001) preferred orientation, in this mensuration; Because the position of sample except the axle (θ) of the angle of diffraction all is fixed, thereby can't estimate actual crystal orientation property.Its result; Because the coexisting state of indeterminate other crystal orientation composition does not perhaps obtain the mensuration result of tight embodiment orientation; So can't hold the deterioration of the piezoelectric property that is caused by structure, the result recognizes the further raising that can't realize piezoelectric constant or the steady production of piezoelectric membrane.
Crystal orientation according to above-mentioned opinion control Pt film and piezoelectric membrane.
[the crystal orientation property of lower electrode layer]
(crystal orientation of Pt film)
Thereby at first; In order strictly to manage and control the crystal orientation property of LKNN film, be used for the optimization of stable realization as crystalline film-forming temperature, film forming gas and the vacuum degree etc. of the Pt film of the lower electrode of the initial crystal growth face of this piezoelectric membrane.As membrance casting condition, at first be carried out to the research of film temperature, as the condition that forms (111) preferred orientation, find that 100 ~ 500 ℃ film forming scope is optimum temperature range.As film forming gas, can use Ar gas, Ar and O
2Mist, or be mixed with He, Ne, Kr and N
2Deng in the gas of at least a above non-active gas.
In addition in order to improve the flatness on Pt surface; Be formed for improving the Ti of the inhomogeneity 0.1nm of conduct and the Ti layer of the close binder of substrate to the surface smoothing of number nm; The Pt electrode is formed at the top through at the Ti layer, can the surface roughness of Pt lower electrode be reduced and be controlled at the size of several nm.
And then accurately control the thickness of Pt lower electrode layer, and reduce the concave-convex surface of Pt lower electrode layer, also can form the Pt lower electrode layer of polycrystalline through the crystal grain size homogenization of control Pt lower electrode layer.
Lower electrode layer, relevant with its crystal orientation property, at the individual layer of the orientation preferentially vertical orientation or the electrode layer of stepped construction with substrate surface.Lower electrode layer not only can for Pt, also can for be the alloy of main component with Pt, or for Pt or be the film (Pt film) of main component with Pt.In addition, can also comprise Au, Ru, Ir, Sn, In and oxide thereof, with piezoelectric membrane in the layer of the compound that forms of contained element.In these situation, the crystallinity of the lower electrode film through likewise being carried out to the optimization of film temperature, film forming gas with the situation of Pt film, can stablizing the substrate that realizes being positioned at the LKNN film.Manufacturing conditions causes the state of the crystal orientation property of piezoelectric membrane to change.In addition, the internal stress of said piezoelectric membrane (strain) is changed to compression stress or tensile stress.Sometimes be stressless state, promptly strainless state.
In addition, as the candidate of the substrate that is used to form these lower electrode films, expect to be Si, MgO, ZnO, SrTiO
3, SrRuO
3, glass, quartz glass, GaAs, GaN, sapphire, Ge, stainless steel etc. crystal or noncrystal or their complex etc.; For on these substrates, being formed with close binder, lower electrode layer, being formed with the device of LKNN film on the top of close binder, lower electrode layer; The crystal orientation property that at length compares the LKNN film, recommending in the reality to choose can the strict substrate of controlling preferred orientation property.
[crystal orientation of piezoelectric membrane]
In addition; In order to realize the preferred orientation property of LKNN film more reliably; In above-mentioned execution mode; Optimization is carried out in heat treatment through after kind, operating gas pressure, vacuum degree, input power and the film forming of seeking film-forming temperature, sputtering operation gas to LKNN film self, thereby has found the manufacturing conditions of this piezoelectric membrane with the crystal orientation property that improves piezoelectric property, has reached purpose.Through making these conditions adapt to each device or various environment; And discuss manufacturing conditions, evaluation and management method etc. in detail and strictly, can reproduce the LKNN film of accurate cube of crystalline substance of the preferred orientation that forms (001) preferred orientation, (111) preferred orientation or both coexistences well.
For the preferred orientation of the LKNN film self of strictly controlling polycrystalline or epitaxially grown monocrystalline, for example, set accurately that film-forming temperature is kept is constant, thereby (001) orientation component or (111) orientation component are fallen in certain proportion.Heater during as actual film forming uses thermal radiation that infrared lamp produces, or uses and utilize the heat conduction that is situated between by the heater heats of heat-conducting plate, falls into the setting in the temperature range that forms only crystal orientation composition ratio.
In addition; Cooperate said condition; Through sputter input power, the pressure that imports the gas in the film formation device or the size of flow are confirmed as only value; And select suitable gaseous species, can expect following effect: comprise (001) orientation and (111) that can obtain strictly to control as crystal structure are oriented in interior various orientation components, stablize and reproduce the LKNN film that obtains showing high piezoelectric constant well.
Specifically, use by Ar and O
2Mist, or be mixed with Ar gas, He, Ne, Kr and N
2Deng in the plasma that produces of the gas of at least a above non-active gas carry out spatter film forming.In the film forming of LKNN piezoelectric membrane, can use (Na
xK
yLi
z) NbO
3The ceramic target of (0≤x≤1.0,0≤y≤1.0,0≤z≤0.2).
In addition, also can pass through to change the density of sputter target material according to above-mentioned situation, and expect same effect.
In addition, can be in oxygen or in the non-active gas after the film forming or both mist in or carry out heat treated in the air or in the vacuum, thereby carry out the control of the internal stress etc. of piezoelectric membrane.
The LKNN film that so obtains has the aggregate structure that the crystal grain by column structure constitutes.In addition, when said lower electrode layer forms at (111) planar orientation, preferred orientation on respect to the prescribed direction of said lower electrode layer and form said piezoelectric thin film layer.
In addition, preferred said piezoelectric thin film layer is the state of at least a coexistence in (001) preferred orientation crystal grain, (110) preferred orientation crystal grain and (111) preferred orientation crystal grain.Through realizing the state of this kind crystal orientation property, can control internal stress and improve piezoelectric property.
The piezoelectric membrane that constitutes the piezoelectric thin film device of embodiment 1 has accurate cube of crystalline substance, regular crystal or orthorhombic crystal structure, perhaps is the state of at least a coexistence in these crystal structures.In addition, piezoelectric membrane some specific axis preferred orientation below 2 in their crystallographic axis.And; Piezoelectric membrane forms: as the composition of the crystallographic axis of said orientation; In the ratio of (001) composition and (111) composition; With the two add up to 100% o'clock, the volume fraction of (001) composition is in 60 to 100% scope, and the volume fraction of (111) composition is in 0 to 40% scope.Through forming this kind formation, can prevent to appear random or internal strain increases and to reduce piezoelectric constant because of crystal orientation.(Figure 16 of embodiment 5 ~ Figure 18)
For with the volume fraction of (001) composition of above-mentioned piezoelectric membrane in 60 to 100% scope, the perhaps mode film forming of volume fraction in 0 to 40% scope of (111) composition; Can realize through the membrance casting condition of control piezoelectric membrane; For example, be controlled to film temperature.(Figure 13 of embodiment 4)
[strain of piezoelectric membrane]
The composition of the crystal orientation property through controlling said piezoelectric membrane is than (volume fraction); The strain that on the direction parallel, has the tensile stress state can be made, perhaps the strain that on the direction parallel, has compressing stress state can be made with real estate with real estate.In addition, through the CONTROL VOLUME mark, can make said piezoelectric membrane is the no strain regime that does not have internal stress.In addition, through the CONTROL VOLUME mark, can make said piezoelectric membrane have uneven strain with the perpendicular or parallel direction of real estate or in two directions.Through so controlling the volume fraction of piezoelectric membrane, can control the internal stress of piezoelectric membrane, can obtain having the piezoelectric membrane of the internal stress of expectation.(Figure 13 of embodiment 4, Figure 14)
[piezoelectric membrane device]
The substrate that has piezoelectric membrane for above-mentioned execution mode; Top electrode layer 15 is formed at the top through at said piezoelectric thin film layer; Can make the piezoelectric thin film device that shows high piezoelectric constant; Again through this piezoelectric thin film device being processed as the regulation shape and voltage applying unit (voltage detection unit) 16 is set, thereby can make piezoelectric membrane devices such as various drivers or transducer.(Figure 21)
In addition,, form pattern electrode 51, can make the filter that utilizes surface acoustic wave with predetermined pattern through top at said piezoelectric membrane for the substrate that has piezoelectric membrane of above-mentioned execution mode.(Figure 22)
In addition, utilize in the filter of surface acoustic wave, said lower electrode (Pt film) mainly plays the effect of basalis.
Be formed at the top of above-mentioned piezoelectric membrane top electrode layer, or have the pattern electrode of predetermined pattern, likewise be preferably Pt with lower electrode layer or with Pt be main component alloy, or comprise the electrode layer of stepped construction that these are the electrode layer of main component with Pt.In addition, also can be comprise Ru, Ir, Sn, In and oxide thereof, with piezoelectric membrane in the electrode layer of stepped construction of electrode layer of the compound that forms of contained element.
[effect of execution mode]
The present invention has following more than one the effect of enumerating.
(1) if adopts more than one execution mode of the present invention; The LKNN piezoelectric membrane has accurate cube of crystalline substance, regular crystal or orthorhombic crystal structure; It perhaps is the state of at least a coexistence in these crystal structures; Some specific axis preferred orientation in their crystallographic axis below 2; And as the composition of the crystallographic axis of said orientation, in the ratio of (001) composition and (111) composition, with the two add up to 100% o'clock; Volume fraction through making (001) composition in 60 to 100% scope, the volume fraction of (111) composition in 0 to 40% scope, can prevent to increase and reduce piezoelectric constant because of crystal orientation presents random, internal strain.
(2) in addition; If adopt more than one execution mode of the present invention; Can be through suitably choosing piezoelectricity film, electrode, substrate, adhesive linkage as constituent material, the manufacturing conditions of attempting this material of optimization is simultaneously accurately measured the crystal orientation degree of the piezoelectric membrane that obtains thus and quantitative exactly; The atomic level structure of strict control piezoelectric membrane improves piezoelectric property.Its result when realizing high performance piezoelectric membrane device, can improve the fabrication yield of this device.
(3) in addition, if adopt more than one execution mode of the present invention,, can control internal stress and improve piezoelectric property through being the state of crystal grain coexistence of crystal grain and (111) preferred orientation of (001) preferred orientation.And then through relaxing stress, can suppress film and peel off, therefore the piezoelectric membrane that mechanical strength improves, ease of processing is excellent of piezoelectric membrane can be provided.
(4) in addition; If adopt more than one execution mode of the present invention; Lower electrode as above-mentioned piezoelectric thin film device; Control the compound that contained element forms in Pt electrode or Pt alloy or Ru, Ir and oxide thereof, Pt and the piezoelectric film of crystal orientation property through use, the crystal orientation property of the piezoelectric film that can High Accuracy Control top forms, improved environment resistant as device.
(5) in addition, if adopt more than one execution mode of the present invention, about substrate, through using Si and MgO substrate, zno-based plate, SrTiO
3Substrate, SrRuO
3Substrate, glass substrate, quartz glass substrate, GaAs substrate, GaN substrate, sapphire substrate, Ge substrate, stainless steel substrate etc. can be controlled on it crystal orientation property of the piezoelectric film that forms.
(6) in addition, if adopt more than one execution mode of the present invention, through this execution mode, can realize the piezoelectric membrane that piezoelectric property is good, and can obtain to high finished product rate high-quality piezoelectric thin film device.
(7) in addition; If adopt more than one execution mode of the present invention; Owing to be to possess the piezoelectric thin film device that does not use plumbous film,, can realize reducing environmental pressure and mini-system devices such as high performance miniature motor, transducer and driver through carrying this piezoelectric thin film device; MEMS (MEMS, Micro Electro Mechanical System) etc. for example.Can realize the filter that utilizes surface acoustic wave and have good filtering characteristic.
(8) in addition; If adopt more than one execution mode of the present invention; When using Si substrate manufacture driver or transducer; Non-lead for the key position that is positioned at piezoelectric device is piezoelectric membrane, owing to control and manage its crystal orientation property quantitatively and accurately, therefore can stably produce life-span length and show that the non-lead of high piezoelectric constant is device.In device, different in addition with the difference at position owing to its crystal orientation property, thus the piezoelectric constant homogenization of the piezoelectric membrane that forms on the substrate, thus the rate of finished products of raising manufacture view.
(9) in addition, if adopt more than one execution mode of the present invention, can control the orientation that uses LKNN etc. and seek to improve piezoelectric property.
(10) in addition; If adopt more than one execution mode of the present invention; Through stably controlling the crystal orientation property of these piezoelectric membranes, can realize that the piezoelectric property of piezoelectric thin film device, piezoelectric membrane device improves or stabilisation, thereby high performance micro device can be provided at an easy rate.
(11) in addition, if adopt more than one execution mode of the present invention,, can access the excellent piezoelectric thin film device or the piezoelectric membrane device of piezoelectric property of the atomic level structure of having controlled piezoelectric membranes such as LKNN accurately according to the present invention.
Embodiments of the invention are described below.
(embodiment 1)
Use Fig. 1 ~ Fig. 8 explanation.
Fig. 1 shows the sectional view of the overview of the substrate that has piezoelectric membrane.In the present embodiment, have formation adhesive linkage 2 on the Si substrate 1 of oxide-film, forming the piezoelectric thin film layer 4 of the lower electrode layer 3 and the KNN of perovskite structure on the top of this adhesive linkage 2 successively, making piezoelectric thin film device.
At this moment, the crystallographic system of said piezoelectric thin film layer 4 be as the criterion cube crystalline substance or regular crystal or orthorhombic, at least a portion of piezoelectric thin film layer 4 can be ABO
3Crystal or noncrystal or both mix composition.At this, A is the element more than a kind that is selected among Li, Na, K, La, Sr, Nd, Ba and the Bi, and B is the element more than a kind that is selected among Zr, Ti, Mn, Mg, Nb, Sn, Sb, Ta and the In, and O is an oxygen.Though the piezoelectric as the A position can consider that from the environment aspect still requirement does not contain the piezoelectric membrane of Pb for containing the formation of Pb.
As lower electrode layer 3, can use Pt film or Au film.Perhaps can be the Pt alloy, contain the alloy of Ir, Ru, also can be their stepped construction.
Below record and narrate the manufacturing approach of piezoelectric thin film device.At first, form heat oxide film, on heat oxide film, form lower electrode layer 3 on the surface of the Si of 4 inches toroidals substrate 1.Wherein, heat oxide film is that the mode of 150nm is provided with thickness.
Then, on this lower electrode layer, form the KNN film as piezoelectric thin film layer 4.Also use sputtering method and form for the film forming of KNN film.At substrate temperature is 700 ℃ ~ 730 ℃, Ar and O
2The condition of plasma that produces of the mist of 5:5 implement spatter film forming down and form the KNN film.In addition, target uses (Na
xK
yLi
z) NbO
3The ceramic target of (x=0.5, y=0.5, z=0).Carrying out film forming is 3 μ m until thickness.In addition, in air, carry out heat treated after the film forming.Wherein, sputter is used from revolving round the sun stove, and the distance during sputter between substrate and target (below, distance between TS) is made as 50mm.
For the KNN film of such making, use observation cross sectional shapes such as scanning electron microscopy, its tissue is made up of column structure.Use conventional X-ray diffraction device investigation crystal structure; Results verification: shown in the X-ray diffractogram (2 θ/θ sweep measuring) of Fig. 2, carry out substrate heating and the Pt film of the embodiment 1 that forms has formed the film of (111) planar orientation vertical with substrate surface.
On the Pt film of this (111) preferred orientation, form the KNN film, results verification: the KNN film of making is the polycrystal film with perovskite type crystal structure of accurate cube of crystalline substance as shown in Figure 3.In addition, can know by the X-ray diffractogram of Fig. 2 because can confirm that (001) is only arranged, the diffraction maximum of (002), (003), thereby measurable KNN piezoelectric membrane is (001) preferred orientation basically.
In present embodiment 1,,, carried out the mensuration of utmost point figure (Pole figure) in order to estimate the orientation of this KNN film in detail and accurately for the KNN piezoelectric membrane of having a mind to control crystal orientation property.Utmost point figure is the figure of expansion of the utmost point of stereoprojection specific lattice face, is the analytical method of state of orientation that can the detailed assessment polycrystalline.Detailed content is please with reference to quoting example 1 (Electric Co., Ltd of science compiles, X-ray diffraction is crossed the threshold (the X-ray diffraction hand draws I), revision the 4th edition, (Electric Co., Ltd of science 1986)), quote example 2 (カ リ テ ィ work, new edition X-ray diffraction will discuss, (ア グ ネ, 1980)).
Mensuration through said utmost point figure can clear and definite preferred orientation definition.For the material that constitutes by polycrystalline (comprising film); When each crystal grain is the state of certain certain direction " preferred orientation "; In the utmost point figure of this material measures, necessarily can find the local distribution of the X ray reflections such as debye ring of hot spot shape or ring-type in specific angle position.
On the other hand, each crystal grain of said material when being " random orientation " in other words, can't find the reflection of the X ray of hot spot shape or ring-type during for direction arbitrarily in utmost point figure.According to having or not of these X ray reflections, can judge whether preferred orientation of this piezoelectric membrane, and the definition that exists as preferred orientation.
In the structural analysis of the piezoelectric thin film device of present embodiment 1; Use is equipped with " D8 DISCOVER with Hi Star, the VANTEC2000 (registered trade mark) " of the high-output power X-ray diffraction device Bruker AXS corporate system of the two-dimensional detector that possesses the large area x-ray detection range.In the present embodiment, measure (110) of KNN film utmost point figure as the utmost point.
Fig. 4 shows the sketch map of the mensuration configuration of the utmost point figure that carries out in the present embodiment.This is the method that is called as Shu Erci (Schultz) bounce technique.During utmost point figure in the past measures; Because the X-ray detector that uses is zero dimension mostly; Therefore need scan (β) axle of χ shown in Figure 4 (α) axle and
simultaneously, need long-time mensuration thereupon.Yet; Owing to used large-area two-dimensional detector (D8 DISCOVER with Hi Star in the present embodiment; VANTEC2000 (registered trade mark)), thereby need follow the action of the zero dimension detector of said 2 scanning hardly, so can measure on short time ground.Therefore, can be in a large number and promptly obtain under various conditions the analysis result of the crystal orientation property of the KNN film of making, thus realize the KNN piezoelectric membrane with crystal structure of present embodiment.
Fig. 5 shows the analysis result of wide-angle reciprocal lattice point diagram in the piezoelectric membrane of embodiment 1.Transverse axis is the x-ray diffraction angle of 2 θ/θ, and the longitudinal axis is axle (the χ axle on the vertical direction of 2 θ/θ) with angle of diffraction shown in Figure 4.In addition, the bar chart on right side is with the intensity of black and white gray scale embodiment X ray reflection, as the benchmark of X ray reflection intensity on same the figure.
Fig. 5 (a) shows the actual analysis result of KNN, and Fig. 5 (b) shows the KNN film reciprocal lattice point Simulation result of (001)/(111) orientation that is used for comparison.Zero representes the diffraction X ray from (001) orientation KNN, ● expression is from the diffraction X ray of (111) orientation KNN.The simulation program that use this moment is the SMAP/for Cross Sectional XRD-RSM that Bruker AXS provides.
Two figure relatively can be known, be about under 32 °, in the scope that with χ=45 ° be 15 ° to 75 ° at center, can confirm (001) orientation and (111) two 110 diffraction in being orientated at 2 θ that are equivalent to 110 diffraction/θ.(001) orientation and the coexistence of (111) orientation in this this piezoelectric membrane of analysis result hint.Owing to only measure and can't measure the axial X-ray diffraction curve of χ with the 2 θ/X-ray diffraction of θ scanning of routine, the analysis result of present embodiment is to have found an example that relates to the new structural parameters that improve the piezoelectric membrane characteristic.
Fig. 6 has shown the X-ray diffraction mensuration result of this actual among the embodiment 1 piezoelectric membrane.Fig. 6 (a) has shown with the diffraction X ray from sample KNN-1 of X ray two-dimensional detector record to have the reflection that the black spots point-like pattern that plots arc is equivalent to the diffraction X ray.In addition, the direction of painting arc is equivalent to described χ direction of principal axis, and the arrow of the normal direction relative with arc is equivalent to the direction of 2 θ/θ.When paying close attention to 2 θ/θ and being about the diffraction X ray under 32 °, observe the overlapping phenomenon of spot of two X ray reflections.Can know the X ray reflection that causes by KNN (111) orientation that is reversed in left side this moment, the X ray reflection of the spot on right side for causing by KNN (001) orientation.
Based on these results,, can show the reflection X-ray spectrum intensity separately that causes by (001) orientation and (111) orientation through setting limit of integration by fan shape.The integration of present embodiment carries out in the scope of 17.5 ° to 72.5 ° on χ axle, the axial integration of 2 θ/θ carries out in 31.4 ° to 32.4 ° scope.
Fig. 6 (b) shows integral result.Transverse axis is the χ axle, the X-ray diffraction intensity of the longitudinal axis for obtaining according to said integral condition.Can find out the reflection X-ray spectrum intensity separately that causes by (001) orientation and (111) orientation.
Fig. 7 shows among the embodiment 1 about the X-ray diffraction of this piezoelectric membrane of the reality of another sample KNN-2 film and measures the result.Likewise can know with Fig. 6, find two spectrums that cause by orientation.Yet can know again; The X ray intensity that is caused by (001) orientation is different with result shown in Figure 6 with the size of the X ray intensity that is caused by (111) orientation, and the X ray intensity that is particularly caused by (001) orientation is obviously different with the ratio of the intensity of the X ray intensity that is caused by (111) orientation.
In the present embodiment, use fitting function that the curve of Fig. 6 (b), Fig. 7 (b) is calculated, implement the quantification of X ray reflection intensity and ratio thereof.
Fig. 8 shows the mensuration result example of (110) utmost point figure of this piezoelectric membrane of embodiment 1.At this shown in Fig. 8 (a); Utmost point footpath direction is made as χ (α) axle, circumferencial direction is made as
(β) axle.On the χ axle of utmost point footpath direction,, the angle of distance center observes the ring (debye ring) of the diffraction surfaces that is equivalent to (001) near being 45 °.On the other hand, near 35.3 °, observe the debye ring of the diffraction surfaces that is equivalent to (111).Especially can know that each debye ring departs from concentrically ringed configuration, but eccentric slightly apart from the center.Results verification is on
of circumferencial direction axle; 0 ° to about 80 ° and about 330 ° to 360 ° scope, overlapping by the reflection X ray that (001) orientation causes with the reflection X ray that causes by (111) orientation.At this moment, the intensity of accurately calculating each orientation component is difficulty very.
Therefore; In order to eliminate this problem points; For mensuration shown in Figure 4 configuration, need to consider the position (at this is equivalent to
axle) of direction of rotation in the face of sample.In addition; When only
axle is indeterminate; Need confirm
axle that reflectance spectrum that is caused by (001) orientation and the reflectance spectrum that is caused by (111) orientation clearly separate based on the mensuration result of utmost point figure.For this reason; Importantly accurately hold the eccentric state of each debye ring, the angle of
axle when finding the angle δ that is equivalent between (001) direction of orientation and (111) direction of orientation to be maximum.
In the present embodiment; In order to obtain this δ exactly, with the footpath of the utmost point shown in Fig. 8 (a) direction be χ (α) axle, circumferencial direction is made as
(β) figure of the orthogonal coordinate system of the figure of the polar coordinates system of the axle axle that converts that transverse axis is made as the χ axle, the longitudinal axis is made as
into.Fig. 8 (b) demonstration converts the figure of
after the orthogonal coordinate system into.Based on Fig. 8 (b), the integrated intensity that carries out each orientation component for the X ray reflection curve on the angle of δ
shaft position (dotted line among Fig. 8 (b)) when maximum calculates.In addition, the integrated intensity that here obtains is through using Gauss (Gauss) function, Lorentz (Lorentz) function and obtaining as their the Pesudo Voight function, the spectrum Fitting Analysis that the Pierre gives birth to distribution functions such as (Pearson) function and Split Pesudo Voight function of convolution function.
Can know according to aforesaid embodiment 1, accurately calculate the intensity of orientation component as long as the X ray reflection curve on the angle that is equivalent to the angle δ between (001) direction of orientation and (111) direction of orientation
shaft position when maximum is carried out the integrated intensity calculating of each orientation component.
(embodiment 2)
With Fig. 9 ~ Figure 10 explanation.
Then, the diffracted intensity of accurately obtaining (001) orientation component and (111) orientation component than the time, be necessary the corrected value of separately X-ray diffraction intensity is discussed.The utmost point figure that for this reason is directed to (001) and (111) investigates.
Fig. 9 shows the analog result of utmost point figure.Fig. 9 (a) is with (001) analog result as the utmost point figure of the utmost point.Shown in this figure, (110) diffraction of KNN that can know (001) orientation has been contributed the diffraction of 4 equivalences.Think that correction coefficient is 4 this moment.On the other hand, by Fig. 9 (b) with (111) analog result as the utmost point figure of the utmost point, (110) diffraction of KNN that can know (111) orientation has been contributed the diffraction of 3 equivalences, so correction coefficient is 3.Therefore, when the volume fraction that the integrated intensity of record calculates (001) orientation of obtaining and (111) orientation in by embodiment 1 was 1:1, actual diffracted intensity was than being (001): (111)=4:3.
Below, Figure 10 shows that the mensuration result of piezoelectric membrane, the Fig. 6 shown in the use embodiment 1 and Fig. 7 of being directed to different KNN-1 of manufacturing conditions and KNN-2 is to (001) and the result of (111) orientation component than analysis.Figure 10 (a) uses fitting function to the curve of the X-ray diffraction shown in Fig. 6 (b) and obtains.Smoothed curve is the Pesudo Voight function that uses as fitting function in the present embodiment.Can know more consistent with the diffraction curve that causes by (111) and (100).At this moment, obtain peak position (χ axle in the present embodiment), integrated intensity and the half-peak breadth of each curve.Be to calculate the diffracted intensity ratio at this because of purpose, so pay close attention to integrated intensity.Figure 10 (b) shows the table that analysis result is concluded.The integrated intensity of enumerating among the embodiment 1, with regard to KNN-1, the integrated intensity of relevant (111) orientation is 298, the integrated intensity of (001) orientation is 2282.
On the other hand, with regard to KNN-2, the former is 241, the latter is 2386.For these integral and calculating result,,, thereby obtain the accurate diffracted intensity of each orientation component as the integrated intensity corrected value shown in Figure 10 (b) through divided by described correction coefficient.If with (001) orientation component and (111) orientation component be made as 100% and analyze; The volume fraction that the result obtains KNN-1 is (001): the volume fraction of (111)=85%:15%, KNN-2 is (001): (111)=88%:12%, can know that orientation component is than different between sample.
(embodiment 3)
With Figure 11, Figure 19 explanation.
The KNN film of the preferred orientation that trial making embodiment 1 relates to.As embodiment 3, Figure 11 shows its schematic cross-section.In addition, Figure 19 shows the skeleton diagram of the RF sputter equipment be used to make the KNN film.Piezoelectric thin film device is: be formed with adhesive linkage 2 having on the Si substrate 1 of oxide-film, be formed with the piezoelectric thin film layer 4 of the lower electrode layer 3 and the KNN of perovskite structure on the top of adhesive linkage 2.At this, the piezoelectric membrane of polycrystalline has by the crystal grain of each column structure (columnar crystal grains) roughly arranges the aggregate structure that forms by certain fixed-direction.
In present embodiment 3; Consistent with substrate 1 center and when carrying out the film forming of KNN piezoelectric membrane 4 at the center that input power is set at 100W, make sputtering target shown in Figure 19 12, can make the piezoelectric membrane of polycrystalline of normal direction basically identical of normal and the real estate of (001) crystal face shown in Figure 11 (a).At this, columnar crystal grains 5 crystalline growth on perpendicular to the direction of substrate.At this moment, in the mensuration of the axonmetric chart that adopts utmost point figure, off-centre is not found with the debye ring of (111) in (001) of drawing, and disposes with concentric circles.In addition; When axle changes the figure of the orthogonal thereto axle of x-y axle into
with the χ axle of described axonmetric chart; Do not see wavy curve, and be linearity.
Below; In the present embodiment; Input power is being set at 100W, is being configured and when implementing film forming according to the position that makes substrate shown in Figure 19 1 centre-to-centre spacing sputtering target 12 off-centrings count 10mm, can confirm to the normal direction of the crystal face of the crystal grain of preferred orientation depart from a little real estate normal direction and at a slant.At this moment, columnar crystal grains 6 is with respect to the normal direction of real estate crystalline growth (Figure 11 (b)) obliquely.In addition, side-play amount is suitably confirmed according to the inclination angle of the substrate size that uses, expectation.In the present embodiment that uses 4 inches Si substrates, side-play amount is made as 10mm.
In the axonmetric chart of the utmost point figure of the present embodiment that side-play amount is made as 10mm, likewise observe two debye rings of (001) and (111) with Fig. 8 (a), can know equally that with Fig. 8 (b) amplitude separately is different.That is, each crystal face of expression (001) and (111) is different with the deflecting angle of real estate.At this moment, the assay value of the amplitude of (001) is 9.9 °.On the other hand, the assay value of the amplitude of (111) is 0.52 °.The result can know, in the piezoelectric membrane of the present invention, and with respect to the normal direction of real estate, about 5 ° of the angle tilt of the crystal orientation direction of (001), about 0.3 ° of the angle tilt of the crystal orientation direction of (111).
(embodiment 4)
With Figure 12 ~ Figure 15 explanation.
Present embodiment shows the result that the volume fraction of the orientation component of the orientation component that changes (001) wittingly and (111) is made.
Figure 12 shows in the spatter film forming method variation with respect to the integrated intensity of the diffraction that is caused and caused by (001) by (111) of film-forming temperature.Can know that the diffracted intensity that caused by (001) reduces with the rising of film-forming temperature.On the other hand, about the diffracted intensity that causes by (111), can know that the rising with film-forming temperature increases.Below, use these results, the film-forming temperature dependence of considering the volume fraction after the correction coefficient shown in the embodiment 2 is discussed.
Figure 13 shows in the spatter film forming method variation with respect to the volume fraction of (111) and (001) orientation component of the film-forming temperature of KNN piezoelectric membrane.Shown in this figure, can know that in 550 ℃ to 650 ℃ film-forming temperature scope the volume fraction of (111) orientation component is 0 basically, and when surpassing 650 ℃, the volume fraction of (111) orientation component increases along with the increase of film-forming temperature.
On the other hand, the variation of the volume fraction of relevant (001) orientation component with respect to film-forming temperature can know that in 550 ℃ to 650 ℃ scope (001) orientation component is 100% basically, almost is merely the autoorientation state of (001) face.Can know that in addition if surpass 650 ℃, the volume fraction of (001) orientation component reduces along with the rising of film-forming temperature gradually.In the present embodiment, demonstration can be through changing over film temperature, the ratio of control (111) orientation component and (001) orientation component.
In addition, Figure 14 shows in the spatter film forming method variation with respect to the internal stress (strain) of the film-forming temperature of KNN piezoelectric membrane.Can know that compression stress reduces, to unstressed strainless state-transition along with film-forming temperature raises.Can know when film-forming temperature is increased to 700 ℃ ~ 750 ℃, by the state that does not have transformation for strain to micro-tensile stress basically.In addition, as the unit example of internal stress in the present embodiment, can enumerate Pa.
As long as relatively can know with Figure 13, because the increase of the volume fraction of (111) manifests the compression stress reduction.Promptly demonstrate,, can realize that the internal stress of this piezoelectric membrane relaxes through increasing (111) orientation component ratio of KNN piezoelectric membrane.The composition that the result can pass through accurately to control crystal orientation property is than (volume fraction), and the internal stress of control piezoelectric membrane.
Because of piezoelectric membrane has the volume fraction of (111) composition,, can suppress film and peel off so can relax the stress of piezoelectric membrane.The piezoelectric membrane that mechanical strength improves, ease of processing is excellent of piezoelectric membrane can be provided thus.
As one of above-mentioned execution mode, Figure 15 shows schematic cross-section.State for crystal grain ([111] axle orientation) 10 coexistences of the crystal grain of (001) preferred orientation ([001] axle orientation) 9 and (111) preferred orientation.Through realizing the state of crystal orientation property shown in figure 15, can control internal stress and improve piezoelectric property.And then, peel off, so the piezoelectric membrane that mechanical strength improves, ease of processing is excellent of piezoelectric membrane can be provided and can suppress film through relaxing stress.
The rate of finished products of the device that can obtain through the substrate of confirming by 4 inches sizes of polylith; The result obtains: by the rate of finished products less than 70% that has the device that the substrate of (111) composition less than 1% piezoelectric membrane obtain, and surpass 90% by the rate of finished products that has the device that the substrate of (111) composition greater than 1% piezoelectric membrane obtain.
According to inventor's result of study, think that this is that size because of the piezoelectric constant deviation in the wafer face causes.The result that the relation of the piezoelectric constant deviation (%) in the volume fraction of (111) orientation component and the wafer face is confirmed is shown in table 1 and Figure 20.Shown in figure 20, but the piezoelectric constant deviation of MS in wafer face, and even if the volume fraction of (111) orientation component is roughly at 1% o'clock, deviation does not also increase but basic fixed.Piezoelectric constant deviation shown here is the standard deviation of the piezoelectric constant in 4 inches wafer face, the measured relative standard deviation after divided by its mean value.This moment, its value was about 23%.Yet (111) volume fraction is about at 0.2% o'clock, and deviation is in 15.3% ~ 27.1% fluctuation, even (111) volume fraction is identical, the difference of piezoelectric constant deviate is also bigger in each wafer, becomes the reason that rate of finished products reduces.
[table 1]
| Sample | (111) volume fraction (%) | Piezoelectric constant deviation (%) |
| |
3.6 | 21.4 |
| |
3.3 | 24.5 |
| |
9.9 | 9.3 |
| |
12.6 | 9.4 |
| |
0.1 | 27.1 |
| |
0.1 | 25.6 |
| |
0.1 | 23.9 |
| |
0.2 | 15.3 |
| Sample 9 | 0.2 | 22.7 |
| |
9.8 | 16.3 |
(embodiment 5)
With Figure 16 ~ Figure 18 explanation.
As present embodiment, Figure 16 shows the variation of the piezoelectric property of KNN piezoelectric membrane with respect to (111) integrated intensity.Transverse axis is (111) integrated intensity, and the longitudinal axis is a piezoelectric constant.At this, the piezoelectric constant when showing the electric field that applies 6.7MV/m or 0.67MV/m as an example.Wherein, the unit of piezoelectric constant is an arbitrary unit, and the concrete example of the piezoelectric constant of conduct reality is the telescopic variation amount d perpendicular to electrode surface (thickness direction)
33, perhaps be telescopic variation amount d along the electrode surface direction
31
Because of following former thereby piezoelectric constant is made as arbitrary unit.In order to obtain piezoelectric constant, need the numerical value such as Young's modulus, Poisson's ratio of piezoelectric body layer, and obtain piezoelectric body layer (piezoelectric membrane) Young's modulus, Poisson's ratio numerical value and be not easy.Especially the situation of film is different with blocks, because the influence of the substrate that uses when receiving self film (constraint etc.), and be not easy to obtain the Young's modulus of film self, the absolute value (true value) of Poisson's ratio (constant) from principle.Thereby use the Young's modulus of at present known KNN film, the presumed value of Poisson's ratio to calculate piezoelectric constant.The piezoelectric constant that cause obtains is a presumed value, in order to embody objectivity, so be made as relative arbitrary unit.Yet, though calculate the Young's modulus of the used KNN film of piezoelectric constant and the value of Poisson's ratio is a presumed value, also be the value of reliability in a way, about 80 [arbitrary units] of piezoelectric constant roughly we can say piezoelectric constant d
31Be 80 [pm/V].This situation is equally applicable to Figure 17 and Figure 18.
Shown in figure 16, when being increased slightly by the X ray intensity that causes of (111) orientation, can be observed piezoelectric constant has trend of rising.Yet the integrated intensity of analyzing in the present embodiment that is caused by (111) surpasses at 100 o'clock, can confirm the increase along with integrated intensity, and the piezoelectric constant dullness reduces.
Then, in order to carry out the comparison with (001) orientation component, table 2 and Figure 17 of table 2 drawing shown the dependence of the piezoelectric property of KNN piezoelectric membrane for (111) orientation component ratio.Transverse axis is the volume fraction of (111) orientation component, and the longitudinal axis is a piezoelectric constant.Can know that in the present embodiment the composition of (111) orientation is in 0 to 20% scope, piezoelectric constant increases along with the increase of (111) volume fraction, and it doesn't matter with the size that applies electric field.
Yet (111) volume fraction surpasses at 20% o'clock, can know that piezoelectric constant will reduce along with this volume fraction increases.Especially surpass at 40% o'clock, can know that piezoelectric constant is about the peaked half the value that obtains in the present embodiment.In other words, as the piezoelectric membrane of present embodiment,, hope that the volume fraction of (111) is more than 40% in order to ensure being more than 5 one-tenth of its maximum piezoelectric constant.In addition, for the piezoelectric property that makes piezoelectric improves, it is also very important to improve degree of crystallinity usually, confirms that the integrated intensity of X-ray diffraction will increase.In the present embodiment, the volume fraction of (111) is 30% when following, and degree of crystallinity is high, if on the basis of realizing high-crystallinity the only volume fraction of regulation, just can realize more high performance piezoelectric membrane.
[table 2]
Below, table 3 and Figure 18 that table 3 is charted show the dependence of the piezoelectric property of KNN piezoelectric membrane for (001) orientation component ratio.The dependence of volume fraction of dependence and (111) that can know (001) volume fraction of piezoelectric constant is negative relation.That is, can know that piezoelectric constant increases along with the increase of (001) orientation component.Yet (001) volume fraction is 80% when above, can know that piezoelectric constant has the trend that reduces.In addition, as the piezoelectric membrane of present embodiment, in order to be embodied as 5 one-tenth above values of its maximum piezoelectric constant, expression hopes that the volume fraction of (001) is more than 60%.In addition, in the present embodiment total of (001) and (111) volume fraction is assumed to 100%.
[table 3]
More than can know; On substrate, dispose in the piezoelectric thin film device of lower electrode, piezoelectric membrane and upper electrode at least; Its piezoelectric membrane has accurate cube of crystalline substance, regular crystal or orthorhombic crystal structure; Perhaps be the state of at least a coexistence in these crystal structures, some the specific axis preferred orientation in their crystallographic axis below 2, and as the composition of the crystallographic axis of said orientation; In the ratio of (001) composition and (111) composition; With the two add up to 100% o'clock, the volume fraction through making (001) composition is in 60 to 100% scope or make the volume fraction of (111) composition in 0 to 40% scope, come accurately to control crystal orientation property, thereby can make novel high performance piezoelectric thin film device.
Like Figure 17, shown in 18, when the piezoelectric thin film device that the substrate that by the volume fraction that has (111) composition is 21%, the volume fraction of (001) composition is 79% piezoelectric membrane is obtained applied voltage 6.7MV/m, piezoelectric constant was 87.The deflecting angle of (001) of the piezoelectric thin film device that obtains and each crystal face of (111) and real estate is: with respect to the normal direction of substrate, and 3.0 ° of the angle tilts of the crystal orientation direction of (001), 0.5 ° of the angle tilt of the crystal orientation direction of (111).
This moment create conditions for: the Si substrate of preparing thickness 0.525mm as substrate, through the surface is imposed thermal oxidation, and form the oxide-film of 200nm on the surface of Si substrate.Then; Under the condition of 350 ℃ of substrate temperatures, input power 100W, Ar gas 100% atmosphere, pressure 2.5Pa, 1 ~ 3 minute (Ti close binder) of film formation time, 10 minutes (Pt lower electrode); Make Ti close binder film forming on heat oxide film of 2nm, and make (111) preferred orientation and Pt lower electrode film forming on the Ti close binder of the 100nm that forms.
Target uses (Na
xK
yLi
z) NbO
3(x=0.5, y=0.5, z=0), target density 4.6g/cm
3Ceramic target, be the mode of 3 μ m is carried out the KNN piezoelectric film on the Pt lower electrode film forming with thickness.Substrate temperature during film forming is 700 ℃, input power 100W, use Ar and O
2The mist of 5:5, pressure is made as 1.3Pa.In addition, the side-play amount at the center of pinwheel and substrate is made as 10mm.In addition, in air atmosphere, carry out 700 ℃, the annealing in process of 2.0hr after the film forming.Wherein, sputter equipment uses from revolving round the sun stove, and distance is made as 50mm between TS.
So; Through suitable selected electrode, piezoelectric membrane etc. as constituent material; Control the membrance casting conditions such as film-forming temperature of piezoelectric membrane simultaneously, and the volume fraction of (001) and (111) composition of the preferred orientation of control piezoelectric membrane, can realize good piezoelectric property.The rate of finished products of the device that in addition, has also obtained being obtained by the substrate that has piezoelectric membrane is 96% enough good result.
More than, though describe the present invention based on the embodiment of limited quantity, scope of the present invention is not limited to these embodiment.For example; As the factor except film-forming temperature; Sputtering target is formed through changing, the kind of flow, pressure or the substrate of the kind of the input power during its film forming, operating gas, this gas, substrate or structure etc., can control crystal orientation property and obtains having the piezoelectric membrane of the internal stress of expectation.Scope of the present invention should be defined by the claims, and comprises the various changes in claim and the equivalency range thereof.
Description of reference numerals
1 Si substrate
2 adhesive linkages
3 lower electrode layers
4 piezoelectric membranes
5 preferred orientation crystal grains
6 with the equidirectional crystal grain of going up preferred orientation of the normal direction of real estate
7 (001) preferred orientation crystal grains
8 (111) preferred orientation crystal grains
The angle of 9 (001) orientation orientation and substrate surface normal
The angle of 10 (111) orientation orientation and substrate surface normal
Claims (11)
1. piezoelectric thin film device, its on substrate, dispose lower electrode at least, with general formula (Na
xK
yLi
z) NbO
3The piezoelectric membrane of expression and the range upon range of body of piezoelectric membrane of upper electrode, wherein, 0≤x≤1,0≤y≤1,0≤z≤0.2, x+y+z=1,
Said piezoelectric membrane has accurate cube of crystalline substance, regular crystal or orthorhombic crystal structure; It perhaps is the state of at least a coexistence in these said crystal structures; Some specific axis preferred orientation in their crystallographic axis below 2; And as the composition of the crystallographic axis of said orientation, in the ratio of (001) composition and (111) composition, with the two add up to 100% o'clock; (001) volume fraction of composition is in the scope more than 60% and below 100%, and the volume fraction of (111) composition is in the scope below 40%.
2. piezoelectric thin film device according to claim 1, it is the structure of said (001) composition and the coexistence of said (111) composition.
3. piezoelectric thin film device according to claim 2, wherein, the volume fraction of said (111) composition is in greater than 1% scope.
4. piezoelectric thin film device, it is for to dispose on substrate with general formula (Na
xK
yLi
z) NbO
3The range upon range of body of piezoelectric membrane of the piezoelectric membrane of expression, wherein, 0≤x≤1,0≤y≤1,0≤z≤0.2, x+y+z=1,
Said piezoelectric membrane has accurate cube of crystalline substance, regular crystal or orthorhombic crystal structure; It perhaps is the state of at least a coexistence in these said crystal structures; Some specific axis preferred orientation in their crystallographic axis below 2; (001) composition as the composition of the crystallographic axis of said preferred orientation is a coexisting state with (111) composition, and in the ratio of (001) composition and (111) composition, with the two add up to 100% o'clock; (001) volume fraction of composition greater than 60% and less than 100% scope in, the volume fraction of (111) composition is in less than 40% scope.
5. piezoelectric thin film device according to claim 4, it has basalis between said substrate and said piezoelectric membrane.
6. piezoelectric thin film device according to claim 5, wherein, said basalis be the Pt film or be the alloy firm of main component with Pt, or for comprising the electrode layer of stepped construction that these are the electrode layer of main component with Pt.
7. according to each described piezoelectric thin film device in the claim 1 to 6, wherein, said piezoelectric membrane has the aggregate structure that the particle by column structure constitutes.
8. according to each described piezoelectric thin film device in the claim 1 to 7, wherein, said piezoelectric membrane has strain in the direction parallel with real estate.
9. piezoelectric thin film device according to claim 8, wherein, said strain has the strain of tensile stress state or the strain of compressing stress state.
10. according to each described piezoelectric thin film device in the claim 1 to 9, wherein, said substrate is the Si substrate.
11. a piezoelectric membrane device, it possesses each described piezoelectric thin film device and voltage applying unit or voltage detection unit in the claim 1 to 10.
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| CN107235723A (en) * | 2016-03-29 | 2017-10-10 | Tdk株式会社 | Piezoelectric ceramics sputtering target material, lead-free piezoelectric thin film and piezoelectric film-type element |
| CN108172683A (en) * | 2016-12-07 | 2018-06-15 | Tdk株式会社 | Piezoelectric membrane laminated body, thin film piezoelectric substrate and piezoelectric film-type element |
| CN110832655A (en) * | 2017-09-22 | 2020-02-21 | Tdk株式会社 | Piezoelectric thin film element |
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| JP2019021994A (en) * | 2017-07-12 | 2019-02-07 | 株式会社サイオクス | Laminate board with piezoelectric film, element with piezoelectric film, and method for manufacturing the laminate board with piezoelectric film |
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| CN102823007B (en) | 2014-04-09 |
| DE112010005432B9 (en) | 2016-11-24 |
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