JP2014168072A - Method for producing pzt ferroelectric thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a ferroelectric thin film with an orientation control layer that has preferred crystal orientation on a plane with a fine-grained crystal texture, by suppressing anomalous grain growth of crystals in the orientation control layer.SOLUTION: A composition for forming a ferroelectric thin film is coated on a lower electrode 11 of a substrate 10 having crystal faces oriented in the 111 axis direction, calcined, and subsequently fired to be crystallized, and thereby a ferroelectric thin film is formed. The composition is coated on the lower electrode and calcined to form a crystal grain diameter control layer having a thickness of 1 nm to 100 nm, then the composition is coated on the crystal grain diameter control layer, calcined, and subsequently fired to form an orientation control layer 13. An amount of coating of the composition is set such that a layer thickness of the orientation control layer after crystallization is in a range of 35 nm to 150 nm, and thereby the orientation control layer 13 has preferred crystal orientation on the 100 plane.

Description

  The present invention relates to a method for easily producing a ferroelectric thin film whose crystal orientation is preferentially controlled on a (100) plane.

  In recent years, development using a ferroelectric thin film as a capacitor or a piezoelectric element has been actively performed due to the demand for further reduction in the size of electronic devices.

  Lead zirconate titanate (PZT) is a ferroelectric material having a perovskite structure and exhibiting excellent dielectric properties. In order to obtain a thin film capacitor using PZT as a dielectric thin film material, the film formation process is inexpensive and a uniform film composition can be obtained on the substrate surface. Therefore, a CSD (chemical solution deposition) method using a sol-gel solution Is attracting attention.

  In forming such a ferroelectric thin film by the CSD method using a sol-gel solution, platinum or iridium having a crystal plane oriented in the (111) axis direction is formed on the substrate as a lower electrode. By forming a ferroelectric thin film thereon, it was possible to obtain a ferroelectric thin film in which the (111) plane was preferentially crystallized depending on the (111) axis direction of the lower electrode. Such a ferroelectric thin film in which the (111) plane is preferentially crystallized has high dielectric strength and high lifetime reliability, and is therefore suitable for applications such as IPD (Integrated Passive Device) and nonvolatile memory.

In order to preferentially orient the (100) plane or the (110) plane on the (111) axially oriented lower electrode, a material different from the ferroelectric thin film may be used as a seed layer. It is known that a material different from the ferroelectric thin film is introduced as a buffer layer that is hardly affected by the lower electrode. A ferroelectric thin film with the (100) plane preferentially crystallized has a large e ₃₁ piezoelectric constant, and is therefore suitable for applications such as actuators. Furthermore, a ferroelectric thin film in which the (110) plane is preferentially crystallized has a large dielectric constant and is suitable for applications such as capacitors.

As a technique for introducing a buffer layer, a method for manufacturing a ferroelectric film is disclosed (for example, see Patent Document 1). The method for manufacturing a ferroelectric film includes a step of forming a base film oriented on a predetermined crystal plane on a substrate, a step of forming a carbon film on the base film, and a ferroelectric material on the carbon film. A step of forming an amorphous thin film, and a step of forming a ferroelectric film on the base film by heating and crystallizing the amorphous thin film. The ferroelectric film manufactured by this method is oriented in a crystal plane different from a predetermined crystal plane, and the ferroelectric material includes perovskite and bismuth layer structure oxide, superconducting oxide, tungsten bronze structure oxide, CaO. , BaO, PbO, ZnO, MgO , B 2 O 3, Al 2 O 3, Y 2 O 3, La 2 O 3, Cr 2 O 3, Bi 2 O 3, Ga 2 O 3, ZrO 2, TiO 2, At least one material selected from the group consisting of HfO ₂ , NbO ₂ , MoO ₃ , WO ₃ and V ₂ O ₅ , a material containing SiO ₂ in at least one material, and SiO ₂ in at least one material ₂ and at least one of materials including GeO ₂ . In Patent Document 1, the crystal orientation of the ferroelectric film formed on the carbon film is controlled by adjusting the film thickness of the carbon film formed as the buffer layer. Specifically, when the film thickness x of a DLC (diamond-like carbon) film, which is a carbon film, is 0 nm <x <10 nm, the orientation of PZT is (111) plane + (001) plane alignment, and the film thickness of the DLC film. When x is x = 10 nm, the orientation of PZT is (001) plane orientation, and when the film thickness x of the DLC film is 10 nm <x <100 nm, the orientation of PZT is (001) plane + (110) plane orientation, When the DLC film thickness x is x = 100 nm, the PZT orientation is (110) plane orientation, and when the DLC film thickness x is 100 nm <x, the PZT orientation is weak (110) plane orientation. It is shown that the crystal orientation is controlled.

Further, in the above-mentioned Patent Document 1, LaNiO ₃ that is strongly self-oriented in the (001) direction is laminated on the (111) -oriented base electrode as a buffer layer, so that (001) It is described that an oriented PZT film can be obtained.

  However, the method disclosed in Patent Document 1 requires a complicated process such as introduction of a seed layer or a buffer layer, and includes such a seed layer or buffer layer, thereby providing a ferroelectric. There is a possibility that the characteristics of the body thin film may be deteriorated or contamination may be caused.

  As a method for controlling the crystal orientation of the ferroelectric thin film, a precursor solution of PZT or PLZT is applied on a platinum substrate having a crystal plane oriented in the (111) axis direction, and heated to form the ferroelectric thin film. In the forming method, after the precursor solution is applied on the substrate, first, heat treatment is performed in a temperature range of 150 to 550 ° C. which brings about a desired crystal orientation, and then baked at 550 to 800 ° C. to be crystallized. A method of controlling the crystal orientation of a ferroelectric thin film, characterized by preferentially orienting the crystal plane of the thin film in a specific axis direction according to the heat treatment temperature (see, for example, Patent Document 2). In this Patent Document 2, the crystal orientation of the ferroelectric thin film is controlled according to the temperature range of the heat treatment corresponding to pre-firing, and the ferroelectric thin film with the crystal orientation controlled on the lower electrode is formed with a seed layer or a buffer layer. Form directly without introducing. Specifically, the (111) plane is preferentially oriented by heat treatment at 150 to 250 ° C., the (111) plane and (100) plane are preferentially oriented by heat treatment at 250 to 350 ° C., and 450 to 550 ° C. It is shown that the (100) plane and the (200) plane preferentially control the orientation and the crystal orientation of the heat treatment.

  In addition, when the Pb-containing perovskite ferroelectric thin film is thin, the generation density of crystal nuclei is reduced and the crystal may grow abnormally, and it is difficult to control the crystal grain size. In this way, the ferroelectric thin film with abnormal grain growth may have inferior insulating properties, and there is a problem in its quality.

JP 2011-29399 A (Claim 7, paragraphs [0003], [0022] to [0026], [0039], FIG. 1) Japanese Patent Laid-Open No. 6-116095 (claims 1-4, paragraphs [0005] and [0006], FIG. 1)

  However, in the method disclosed in Patent Document 2, the preferred orientation obtained is (111) plane and (100) plane, or (100) plane and (200) plane, and the preferred orientation is a plurality of orientation planes. However, its application is limited, or even if it is used for a specific application, its performance cannot be fully exhibited.

An object of the present invention is to provide a method for producing a ferroelectric thin film having an orientation control layer preferentially crystallized in the (100) plane with a fine crystal structure by suppressing abnormal grain growth of crystals in the orientation control layer. It is to provide.

  Another object of the present invention is to produce a ferroelectric thin film capable of arbitrarily adjusting the film thickness of the ferroelectric thin film whose crystal orientation is preferentially controlled on the (100) plane according to the application. It is to provide a method.

  The present inventors diligently studied the conventional ferroelectric thin film preferentially oriented, and when forming the ferroelectric thin film using the sol-gel method, the lower electrode whose crystal plane is oriented in the (111) axial direction is formed. A layer thickness obtained by applying a composition for forming a ferroelectric thin film on a lower electrode of a substrate, drying and pre-baking the gel film, and crystallizing the resulting film is within a specific range. By doing so, it is possible to easily obtain a ferroelectric thin film whose crystal orientation is controlled preferentially on the (100) plane without depending on the (111) axis direction of the lower electrode without providing a seed layer or a buffer layer. In addition, if a ferroelectric thin film whose crystal orientation is preferentially controlled on the (100) plane obtained as described above is used as a base layer, and a ferroelectric thin film is further formed on the base layer, the film thickness can be increased. Regardless of the strength, it has the same crystal orientation as that of the underlying layer. An electric thin film can be obtained, and before forming a ferroelectric thin film whose crystal orientation is preferentially controlled on the (100) plane, a crystal grain size control layer is provided as a layer for increasing the generation density of nuclei. Introducing a ferroelectric thin film in which the crystal orientation is controlled preferentially in the (100) plane with a fine crystal structure by suppressing the abnormal grain growth of the crystal by introducing the present invention. Completed.

As shown in FIG. 2 , a first aspect of the present invention is that a composition for forming a ferroelectric thin film is formed on a lower electrode 11 of a substrate 10 having a lower electrode 11 having a crystal plane oriented in the (111) axis direction. In a method for producing a ferroelectric thin film on the lower electrode 11 by applying and crystallizing by heating, a composition for forming a ferroelectric thin film is applied on the lower electrode 11 and calcined to have a layer thickness of 1 nm. A crystal grain size control layer 12 having a thickness of 10 nm to 10 nm is formed, and a ferroelectric thin film forming composition is applied onto the crystal grain size control layer 12 and calcined, and then fired to form an orientation control layer. The preferential crystal orientation of the orientation control layer 13 is set by setting the coating amount of the composition for forming a dielectric thin film so that the thickness of the orientation control layer 13 after crystallization is in the range of 35 nm to 150 nm (100). It is characterized by having a surface .

A second aspect of the present invention is an invention based on the first aspect, characterized in that the calcining temperature for forming the crystal grain size control layer 12 is in the range of 175 ° C. to 315 ° C. .

A third aspect of the present invention is an invention based on the first aspect or the second viewpoint, coating a portion of the ferroelectric thin film-forming composition on the lower electrode 11, calcining, and firing After forming the orientation control layer 13, the remainder of the composition for forming a ferroelectric thin film is applied onto the orientation control layer 13, calcined, and fired to have the same crystal orientation as that of the orientation control layer 13. The adjustment layer 14 is formed.

A fourth aspect of the present invention is an invention based on the third aspect , wherein the calcining temperature for forming the film thickness adjusting layer 14 after applying the remainder of the composition for forming a ferroelectric thin film is 200. It is characterized by being in the range of from ℃ to 450 ℃.

A fifth aspect of the present invention is an invention based on any one of the first to fourth aspects, wherein the ferroelectric thin film is a Pb-containing perovskite oxide, and the ferroelectric thin film The forming composition contains a β-diketone and a polyhydric alcohol.

A sixth aspect of the present invention is an invention based on the fifth aspect , characterized in that the β -diketone is acetylacetone and the polyhydric alcohol is propylene glycol.

A seventh aspect of the present invention is a ferroelectric thin film preferentially crystallized in the (100) plane manufactured by a method based on any one of the first to sixth aspects .

An eighth aspect of the present invention is a thin film capacitor having a ferroelectric thin film based on the seventh aspect , a capacitor, an IPD, a DRAM memory capacitor, a multilayer capacitor, a gate insulator of a transistor, a nonvolatile memory, a pyroelectric infrared It is a composite electronic component of a detection element, a piezoelectric element, an electro-optical element, an actuator, a resonator, an ultrasonic motor, or an LC noise filter element.

In the first aspect of the present invention, a composition for forming a ferroelectric thin film is applied onto a lower electrode of a substrate having a lower electrode having a crystal plane oriented in the (111) axis direction, and calcined to obtain a layer thickness. A crystal grain size control layer of 1 nm to 10 nm is formed, the ferroelectric thin film forming composition is applied on the crystal grain size control layer, calcined, and then fired to form an orientation control layer. The application amount of the composition for forming a ferroelectric thin film is set so that the thickness of the orientation control layer after crystallization is in the range of 35 nm to 150 nm, and the preferential crystal orientation of the orientation control layer is set to (100 ) Face. Thus, after forming the crystal grain size control layer, by providing the orientation control layer on the crystal grain size control layer, abnormal grain growth of the crystals in the orientation control layer can be suppressed. As a result, the orientation control is controlled. The layer can be preferentially crystallized in the (100) plane with a fine crystal structure.

In the second aspect of the present invention, the calcining temperature for forming the crystal grain size control layer is in the range of 175 ° C. to 315 ° C. , so that the temperature is between 175 ° C. and 315 ° C. (100) Oriented initial nuclei can be generated.

In the third aspect of the present invention, after forming the orientation control layer, a film thickness adjusting layer having the same crystal orientation as that of the orientation control layer is formed, whereby the crystal orientation is preferentially formed on the (100) plane. The film thickness of the ferroelectric thin film in which is controlled can be arbitrarily adjusted according to the application .

It is sectional drawing of the ferroelectric thin film formed on the board | substrate which is reference embodiment of this invention. Is a cross-sectional view of a ferroelectric thin film formed on a substrate is the implementation form of the present invention. Examples 1 and 2, 5, 6, 9, 11 and 12, is a view showing an XRD pattern of 13, 15, 16, 19, 20. Examples 1, 2, 5, 6, 9, and 11 are not examples but reference examples. It is a figure which shows the XRD pattern of the comparative examples 1, 2, and 3. FIG. Comparative examples 2 and 3 are reference comparative examples. 10 is a surface SEM image of Reference Example 9 (magnification 10,000 times). It is a surface SEM image of Example 13 (magnification 50000 times).

Next, an embodiment for carrying out the present invention will be described with reference to the drawings.
In the present invention, as shown in FIG. 2 , a ferroelectric thin film forming composition is applied onto a lower electrode 11 of a substrate 10 having a lower electrode 11 whose crystal plane is oriented in the (111) axis direction, and heated. This is an improvement of the method of manufacturing the ferroelectric thin film 13 on the lower electrode 11 by crystallization.

A characteristic configuration of the present invention is that a ferroelectric thin film forming composition is applied onto the lower electrode 11 and calcined to form a crystal grain size control layer 12 having a layer thickness of 1 nm to 10 nm. The composition for forming a ferroelectric thin film is applied onto the layer 12, calcined, and then fired to form an orientation control layer, and the amount of the composition for forming the ferroelectric thin film is crystallized from the orientation control layer 13. The subsequent layer thickness is set in the range of 35 nm to 150 nm, and the preferential crystal orientation of the orientation control layer 13 is set to the (100) plane . Thus, by setting the layer thickness after crystallization of the orientation control layer 13 to be formed in the range of 35 nm to 150 nm, the ferroelectric thin film whose crystal orientation is controlled preferentially on the (100) plane is formed as a seed layer. Or without providing a buffer layer. Thus, by setting the layer thickness after crystallization within the above range, the resulting orientation control layer 13 can be preferentially crystallized in the (100) plane so that the surface energy is minimized. This is probably due to self-orientation. The thickness of the orientation control layer 13 after crystallization is 35 nm to 150 nm. If it is less than 35 nm, it is not preferable because other orientations such as (110) orientation are obtained, and if it exceeds 150 nm, other orientations are similarly undesirable. More preferably, it is 45 nm-90 nm. The reason for this preferable range is that if the temperature range is less than 45 nm, the optimum temperature range of the calcining conditions is narrow and it is difficult to stably obtain (100) orientation. This is because it becomes narrower. Further, by forming an orientation control layer on the crystal grain size control layer 12 after forming the crystal grain size control layer 12, the generation density of nuclei can be increased, so that abnormal grain growth of crystals in the orientation control layer 13 can be achieved. As a result, it is possible to obtain the orientation control layer 13 having a fine crystal structure and crystal orientation preferentially in the (100) plane.

FIG. 1 is a cross-sectional view showing a ferroelectric thin film formed on a substrate which is a reference embodiment having no characteristic crystal grain size control layer of the present invention .

  As the substrate 10 for manufacturing the ferroelectric thin film, a heat resistant substrate such as a silicon substrate or a sapphire substrate is used. Further, as the lower electrode 11 in which the crystal plane formed on the substrate 10 is oriented in the (111) axis direction, a material having conductivity such as Pt, Ir, Ru, etc., which does not react with the ferroelectric thin film is used. . The ferroelectric thin film to be produced is preferably a Pb-containing perovskite oxide, and examples thereof include PZT, PLZT, PMnZT, and PNbZT.

  The composition for forming a ferroelectric thin film is composed of an organometallic compound solution dissolved in an organic solvent so that the raw materials for constituting the composite metal oxide have a ratio that gives a desired metal atomic ratio. .

The composite metal oxide raw material is preferably a compound in which an organic group is bonded to each metal element of Pb, La, Zr, and Ti through an oxygen or nitrogen atom. For example, one kind selected from the group consisting of metal alkoxide, metal diol complex, metal triol complex, metal carboxylate, metal β-diketonate complex, metal β-diketoester complex, metal β-iminoketo complex, and metal amino complex Or 2 or more types are illustrated. Particularly suitable compounds are metal alkoxides, partial hydrolysates thereof, and organic acid salts. Among these, as Pb compounds and La compounds, acetate salts (lead acetate: Pb (OAc) ₂ , lanthanum acetate: La (OAc) ₃ ), lead diisopropoxide: Pb (OiPr) ₂ , lanthanum triisopropoxide : La (OiPr) _{3 and the} like. As the Ti compound, titanium tetraethoxide: Ti (OEt) ₄ , titanium tetraisopropoxide: Ti (OiPr) ₄ , titanium tetra n-butoxide: Ti (OiBu) ₄ , titanium tetraisobutoxide: Ti (OiBu) ₄ And alkoxides such as titanium tetra-t-butoxide: Ti (OtBu) ₄ and titanium dimethoxydiisopropoxide: Ti (OMe) ₂ (OiPr) ₂ . The Zr compound is preferably an alkoxide similar to the Ti compound. Although the metal alkoxide may be used as it is, a partially hydrolyzed product thereof may be used in order to promote decomposition.

  In order to prepare a composition for forming a ferroelectric thin film, these raw materials are dissolved in an appropriate solvent at a ratio corresponding to the desired ferroelectric thin film composition, and adjusted to a concentration suitable for coating.

  In this adjustment, typically, a composition for forming a ferroelectric thin film that becomes a precursor solution can be obtained by the following liquid synthesis flow. A reaction vessel is charged with a Zr source (eg, Zr tetra-n-butoxide), a Ti source (eg, Ti isopropoxide), and a stabilizer (eg, acetylacetone), and refluxed in a nitrogen atmosphere. Next, a Pb source (eg, lead acetate trihydrate) is added to the refluxed compound, a solvent (eg, propylene glycol) is added, the mixture is refluxed in a nitrogen atmosphere, and distilled under reduced pressure to produce a by-product. After removal, additional proisoglycol is added to the solution to adjust the concentration, and n-butanol is added to the solution. As a result, the composition for forming a ferroelectric thin film is obtained.

  The solvent of the composition for forming a ferroelectric thin film used here is appropriately determined according to the raw material to be used. Generally, a carboxylic acid, an alcohol (for example, propylene glycol which is a polyhydric alcohol), an ester, Ketones (eg acetone, methyl ethyl ketone), ethers (eg dimethyl ether, diethyl ether), cycloalkanes (eg cyclohexane, cyclohexanol), aromatics (eg benzene, toluene, xylene), other tetrahydrofuran, Or these 2 or more types of mixed solvents can be used.

  Specific examples of the carboxylic acid include n-butyric acid, α-methylbutyric acid, i-valeric acid, 2-ethylbutyric acid, 2,2-dimethylbutyric acid, 3,3-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3-methylpentanoic acid, 4-methylpentanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, 2,2-dimethylpentanoic acid, 3,3-dimethylpentanoic acid, 2,3-dimethylpentanoic acid, 2- It is preferable to use ethylhexanoic acid or 3-ethylhexanoic acid.

  As the ester, ethyl acetate, propyl acetate, n-butyl acetate, sec-butyl acetate, tert-butyl acetate, isobutyl acetate, n-amyl acetate, sec-amyl acetate, tert-amyl acetate, isoamyl acetate are used. As the alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, iso-butyl alcohol, 1-pentanol, 2-pentanol, 2-methyl-2-pentanol, 2-methoxy It is preferred to use ethanol.

  The total concentration of the organometallic compound in the organometallic compound solution of the ferroelectric thin film forming composition is preferably about 0.1 to 20% by mass in terms of metal oxide.

  In this organometallic compound solution, β-diketones (for example, acetylacetone, heptafluorobutanoylpivaloylmethane, dipivaloylmethane, trifluoroacetylacetone, benzoylacetone, etc.) are used as stabilizers as necessary. , Β-ketone acids (for example, acetoacetic acid, propionylacetic acid, benzoylacetic acid, etc.), β-ketoesters (for example, lower alkyl esters such as methyl, propyl, and butyl of the above ketone acids), oxyacids (for example, lactic acid, Glycolic acid, α-oxybutyric acid, salicylic acid, etc.), lower alkyl esters of the above oxyacids, oxyketones (eg, diacetone alcohol, acetoin, etc.), diols, triols, higher carboxylic acids, alkanolamines (eg, diethanolamine, Triethanolamine, Roh ethanolamine), a polyvalent amine or the like, may be added from 0.2 to 3 approximately at (stabilizer number of molecules) / (number of metal atoms).

  The composition for forming a ferroelectric thin film preferably contains a β-diketone and a polyhydric alcohol. Of these, acetylacetone is particularly preferable as the β-diketone, and propylene glycol is particularly preferable as the polyhydric alcohol.

  Particles are removed from the prepared organometallic compound solution by filtration or the like, and the number of particles having a particle size of 0.5 μm or more (especially 0.3 μm or more, especially 0.2 μm or more) is 50 or less per mL of solution ( 50 / mL or less). When the number of particles having a particle diameter of 0.5 μm or more in the organometallic compound solution exceeds 50 particles / mL, long-term storage stability is deteriorated. The smaller the number of particles having a particle size of 0.5 μm or more in this organometallic compound solution, the more preferable, and particularly preferably 30 particles / mL or less.

  The method for treating the organometallic compound solution after preparation so as to achieve the number of particles is not particularly limited, and examples thereof include the following method. The first method is a filtration method in which a commercially available membrane filter having a pore size of 0.2 μm is used and pressure-fed with a syringe. The second method is a pressure filtration method in which a commercially available membrane filter having a pore size of 0.05 μm and a pressure tank are combined. The third method is a circulation filtration method in which the filter used in the second method and the solution circulation tank are combined.

  In any method, the particle capture rate by the filter varies depending on the solution pressure. It is generally known that the lower the pressure, the higher the capture rate. In particular, in the first method and the second method, the number of particles having a particle size of 0.5 μm or more is set to 50 or less. In order to achieve, it is preferable to pass the solution through the filter very slowly at low pressure.

  In order to form a ferroelectric thin film using the composition for forming a ferroelectric thin film, the composition is spin-coated, dip-coated, or LSMCD (Liquid Source Misted) on the lower electrode oriented in the (111) axial direction. The film is coated using a coating method such as Chemical Deposition), dried and pre-baked using a hot plate, etc., and the steps from coating to drying / pre-baking are repeated to obtain a gel film having a layer thickness within a desired range. It is obtained by carrying out main baking in a lump after forming.

  The drying / pre-baking is performed in order to remove the solvent and thermally decompose or hydrolyze the organometallic compound to convert it into a composite oxide. Therefore, it is performed in air, in an oxidizing atmosphere, or in a steam-containing atmosphere. Even in heating in the air, the moisture required for hydrolysis is sufficiently secured by the humidity in the air. This heating may be performed in two stages: low temperature heating for removing the solvent and high temperature heating for decomposing the organometallic compound.

The main baking is a process for baking and crystallizing the thin film obtained by drying and pre-baking at a temperature higher than the crystallization temperature, whereby a ferroelectric thin film is obtained. The firing atmosphere in this crystallization step is preferably O ₂ , N ₂ , Ar, N ₂ O, H _2, or a mixed gas thereof.

Drying and calcination are performed at 150 to 550 ° C. for about 1 to 10 minutes. Here, regarding the above temperature range, in the case of the reference embodiment in which the crystal grain size control layer is not introduced into the ferroelectric thin film, the temperature may be in the range of 150 ° C. to 200 ° C. or 285 ° C. to 315 ° C. desirable. This is because when the temperature is around 250 ° C., the heating temperature of the film is not appropriate, and initial nuclei having a (100) orientation are not generated at the interface between the substrate and the film. On the other hand, when the crystal grain size control layer according to the present embodiment is introduced into the ferroelectric thin film, it is desirable to set the temperature within the range of 175 ° C. to 315 ° C. This is because the introduction of a crystal grain size control layer having a low crystallization temperature generates initial nuclei with (100) orientation between 175 ° C. and 315 ° C.

  The main baking is performed at 450 to 800 ° C. for about 1 to 60 minutes. The main baking may be performed by rapid heating treatment (RTA treatment). When the main baking is performed by the RTA treatment, the temperature rising rate is preferably 10 to 100 ° C./second.

  Examples of the crystal grain size control layer 12 include lead titanate, lead zirconate titanate, and lead zirconate. The layer thickness of the crystal grain size control layer 12 is preferably 1 nm to 10 nm. The reason why the thickness of the crystal grain size control layer 12 is within the above range is that if it exceeds 10 nm, the effect of improving the nucleus generation density cannot be obtained, and as a result, a fine crystal structure cannot be obtained.

  The crystal grain size control layer 12 is spin-coated and dip coated with the composition for the crystal grain size control layer on the lower electrode oriented in the (111) axial direction in the same manner as the orientation control layer 13 is formed. , Applied using a coating method such as LSMCD (Liquid Source Misted Chemical Deposition) method, dried and pre-baked in an air atmosphere at 150 to 550 ° C. for 1 to 10 minutes using a hot plate or the like. It is obtained by repeating the steps up to pre-baking to form a gel film having a layer thickness within a desired range. When the crystal grain size control layer 12 is provided, the orientation control layer 13 is formed on the crystal grain size control layer 12.

  Further, after forming the orientation control layer 13, it is preferable to form the film thickness adjusting layer 14 having the same crystal orientation as the crystal orientation of the underlayer on the underlayer using the orientation control layer 13 as the underlayer. is there. By forming the film thickness adjusting layer 14 on the underlayer, a crystal orientation plane having the same tendency as the orientation control layer 13 is formed following the preferential orientation plane of the orientation control layer 13. 14 makes it possible to arbitrarily adjust the film thickness of the ferroelectric thin film whose crystal orientation is preferentially controlled in the (100) plane by the orientation control layer in accordance with the application.

  The film thickness adjusting layer 14 is a Pb-containing perovskite ferroelectric film of the same type as the orientation control layer 13. The thickness of the film thickness adjusting layer 14 is preferably less than 5000 nm. The reason why the thickness of the film thickness adjusting layer 14 is within the above range is that the process time becomes longer at 5000 nm or more, and the tendency to follow the preferential alignment surface of the alignment control layer 13 decreases, and as a result, the (100) surface This is because the degree of orientation becomes small.

  The film thickness adjusting layer 14 is formed on the alignment control layer 13 by spin coating, dip coating, or LSMCD (Liquid Source Misted Chemical Deposition). ) Coating using a coating method, etc., and drying and pre-baking at 150 to 550 ° C. for 1 to 10 minutes in an air atmosphere using a hot plate or the like, and repeating the steps from coating to drying and pre-baking It is obtained by forming a gel film having a film thickness within a desired range, followed by main baking at 450 to 800 ° C. for 1 to 60 minutes in an oxygen atmosphere.

The ferroelectric thin film of the present invention thus manufactured has a crystal orientation controlled preferentially on the (100) plane and has a large e ₃₁ piezoelectric constant.

  The ferroelectric thin film of the present invention includes a thin film capacitor, a capacitor, an IPD, a DRAM memory capacitor, a multilayer capacitor, a transistor gate insulator, a nonvolatile memory, a pyroelectric infrared detection element, a piezoelectric element, an electro-optical element, It can be used as a constituent material in composite electronic parts of actuators, resonators, ultrasonic motors, or LC noise filter elements.

Next, examples of the present invention will be described in detail together with comparative examples. Examples 1 to 11 shown below are reference examples, not examples, and Comparative Examples 2 and 3 are reference comparative examples.

<Preparation of Crystal Grain Size Control Layer Composition, Orientation Control Layer Composition, and Film Thickness Adjustment Layer Composition>
The liquid synthesis flow of these compositions typically followed the following process.

  First, zirconium tetra n-butoxide (Zr source) and / or titanium tetraisopropoxide (Ti source) and acetylacetone (stabilizer) were placed in a reaction vessel and refluxed in a nitrogen atmosphere. Next, lead acetate trihydrate (Pb source) is added to this compound, and propylene glycol (solvent) is added. The mixture is refluxed in a nitrogen atmosphere and distilled under reduced pressure to remove by-products. Further, propylene glycol was added to adjust the concentration, and n-butanol was further added to this solution to obtain the above composition to be a precursor solution.

  Moreover, the liquid synthesis flow of the composition specifically followed the following process.

  First, Ti isopropoxide (Ti source) and acetylacetone (stabilizer) were placed in a reaction vessel and refluxed in a nitrogen atmosphere. Next, lead acetate trihydrate (Pb source) is added to this compound, and propylene glycol (solvent) is added, refluxed in a nitrogen atmosphere, and distilled under reduced pressure to remove by-products. Further, propylene glycol was added to adjust the concentration, and further diluted alcohol was added to adjust the concentrations to the concentrations shown in Table 1 and Table 2 below. A composition for a crystal grain size control layer containing a metal compound of = 125/100 was obtained.

First, Zr tetra n-butoxide (Z source), Ti isopropoxide (Ti source), and acetylacetone (stabilizer) were placed in a reaction vessel and refluxed in a nitrogen atmosphere. Next, lead acetate trihydrate (Pb source) is added to this compound, and propylene glycol (solvent) is added. The mixture is refluxed under a nitrogen atmosphere and distilled under reduced pressure to remove by-products. Further, propylene glycol was added to adjust the concentration, and further diluted alcohol was added to adjust the desired concentration shown in Tables 1 and 2 below. A composition for orientation control layer and a composition for film thickness adjusting layer containing a metal compound of Zr / Ti = 110/52/48 were obtained. Each organometallic compound solution constituting the composition for crystal grain size control layer, the composition for orientation control layer, and the composition for film thickness adjustment layer uses a commercially available membrane filter having a pore size of 0.2 μm and is pumped with a syringe. As a result of filtration, the number of particles having a particle size of 0.5 μm or more was 1, 2 and 1 per 1 mL of the solution, respectively.

<Example 1>
As a substrate, a 6-inch silicon substrate having a Pt lower electrode film formed on the surface by a sputtering method was prepared. On the Pt lower electrode film of this substrate, the above prepared composition for an orientation control layer having a concentration of 10% by mass was applied by spin coating under the conditions of 500 rpm for 3 seconds and then 3500 rpm for 15 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After performing the steps of applying the composition for orientation control layer and pre-firing once, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer thickness. A 35 nm orientation control layer was obtained. This was used as the ferroelectric thin film of Example 1.

<Example 2>
A substrate similar to that of Example 1 was prepared, and the above prepared 12 mass% concentration orientation control was performed on the Pt lower electrode film of the substrate by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 15 seconds. The layer composition was applied. Subsequently, drying and pre-baking were performed by heating at 150 ° C. for 5 minutes in an air atmosphere using a hot plate. The composition for orientation control layer was crystallized by performing main firing at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature elevation rate of 10 ° C./second to obtain an orientation control layer having a layer thickness of 60 nm. This was used as the ferroelectric thin film of Example 2.

<Example 3>
A substrate similar to that in Example 1 was prepared, and the above prepared 12 mass% concentration control was performed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. The layer composition was applied. Subsequently, drying and pre-baking were performed by heating at 150 ° C. for 5 minutes in an air atmosphere using a hot plate. After performing the steps of applying the composition for orientation control layer and pre-firing once, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer thickness. A 75 nm alignment control layer was obtained. This was designated as the ferroelectric thin film of Example 3.

<Example 4>
A substrate similar to that in Example 1 was prepared, and the above prepared 10 mass% concentration orientation control was performed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 15 seconds. The layer composition was applied. Subsequently, drying and pre-baking were performed by heating at 175 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the composition for orientation control layer and pre-firing twice, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer thickness. A 90 nm orientation control layer was obtained. Next, the composition for film thickness adjusting layer having a concentration of 10% by mass prepared above was applied on the orientation control layer by spin coating under conditions of 3000 rpm for 15 seconds. Subsequently, drying and pre-baking were performed by heating at 175 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-baking 6 times, the film was crystallized by performing main baking at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second, A film thickness adjusting layer having a thickness of 270 nm was obtained. This was designated as the ferroelectric thin film of Example 4.

<Example 5>
A substrate similar to that of Example 1 was prepared, and the above prepared 5 mass% concentration orientation control was performed on the Pt lower electrode film of the substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 15 seconds. The layer composition was applied. Subsequently, after heating and drying at 175 ° C. for 5 minutes in an air atmosphere using a hot plate, a heating and heating process is performed at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. Baking was performed to crystallize to obtain an orientation control layer having a layer thickness of 75 nm. Next, the composition for film thickness adjusting layer having a concentration of 10% by mass prepared above was applied on the orientation control layer by spin coating under conditions of 3000 rpm for 15 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-baking 6 times, the film was crystallized by performing main baking at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second, A film thickness adjusting layer having a thickness of 270 nm was obtained. This was designated as the ferroelectric thin film of Example 5.

<Example 6>
A substrate similar to that of Example 1 was prepared, and the above prepared 5 mass% concentration orientation control was performed on the Pt lower electrode film of the substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 15 seconds. The layer composition was applied. Subsequently, using a hot plate, drying and pre-baking were performed by heating at 200 ° C. for 5 minutes in an air atmosphere. After repeating the steps of applying the composition for orientation control layer and pre-firing three times, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer thickness. A 60 nm alignment control layer was obtained. This was designated as the ferroelectric thin film of Example 6.

<Example 7>
A substrate similar to that in Example 1 was prepared, and the above prepared 12 mass% concentration control was performed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. The layer composition was applied. Subsequently, after drying and pre-baking by heating at 200 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. And crystallized to obtain an orientation control layer having a layer thickness of 75 nm. This was designated as the ferroelectric thin film of Example 7.

<Example 8>
A substrate similar to that in Example 1 was prepared, and the above prepared 12 mass% concentration control was performed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. The layer composition was applied. Subsequently, after drying and pre-baking by heating at 200 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. And crystallized to obtain an orientation control layer having a layer thickness of 75 nm. Next, the above-prepared composition for a film thickness adjusting layer having a concentration of 5% by mass was applied on the orientation control layer by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. Subsequently, after drying and pre-baking by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. The film was crystallized to obtain a film thickness adjusting layer having a layer thickness of 20 nm. This was designated as the ferroelectric thin film of Example 8.

<Example 9>
A substrate similar to that in Example 1 was prepared, and the above prepared 12 mass% concentration control was performed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. The layer composition was applied. Subsequently, after drying and pre-baking by heating at 200 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. And crystallized to obtain an orientation control layer having a layer thickness of 75 nm. Next, the above-prepared composition for a film thickness adjusting layer having a concentration of 12% by mass was applied on the orientation control layer by spin coating under the conditions of 500 rpm for 3 seconds and then 2000 rpm for 20 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-firing four times, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer. A film thickness adjusting layer having a thickness of 300 nm was obtained. This was designated as the ferroelectric thin film of Example 9.

<Example 10>
A substrate similar to that in Example 1 was prepared, and the above prepared 12 mass% concentration control was performed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. The layer composition was applied. Subsequently, after drying and pre-baking by heating at 315 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. And crystallized to obtain an orientation control layer having a layer thickness of 75 nm. Next, the composition for film thickness adjusting layer having a concentration of 10% by mass prepared above was applied on the orientation control layer by spin coating under conditions of 3000 rpm for 15 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-baking 6 times, the film was crystallized by performing main baking at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second, A film thickness adjusting layer having a thickness of 270 nm was obtained. This was designated as the ferroelectric thin film of Example 10.

<Example 11>
A substrate similar to that in Example 1 was prepared, and the above prepared 12 mass% concentration control was performed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. The layer composition was applied. Subsequently, after drying and pre-baking by heating at 175 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a heating rate of 10 ° C./second. And crystallized to obtain an orientation control layer having a layer thickness of 75 nm. Next, the composition for film thickness adjusting layer having a concentration of 10% by mass prepared above was applied on the orientation control layer by spin coating under conditions of 3000 rpm for 15 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-baking 6 times, the film was crystallized by performing main baking at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second, A film thickness adjusting layer having a thickness of 270 nm was obtained. This was designated as the ferroelectric thin film of Example 11.

<Example 12>
A substrate similar to that in Example 1 was prepared, and the 1% by mass concentration crystal grains prepared above were formed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. A composition for a diameter control layer was applied. Subsequently, using a hot plate, heating and drying at 175 ° C. for 5 minutes in an air atmosphere were performed to perform pre-baking and obtain a crystal grain size control layer having a layer thickness of 2 nm. Next, the 12% by mass concentration composition for orientation control layer prepared above was applied on the crystal grain size control layer by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. Subsequently, after drying and pre-baking by heating at 175 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a heating rate of 10 ° C./second. This was crystallized to obtain an orientation control layer having a layer thickness of 60 nm. This was designated as the ferroelectric thin film of Example 12.

<Example 13>
A substrate similar to that in Example 1 was prepared, and the 1% by mass concentration crystal grains prepared above were formed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. A composition for a diameter control layer was applied. Subsequently, using a hot plate, heating and drying at 200 ° C. for 5 minutes in an air atmosphere were performed, followed by drying and pre-baking to obtain a crystal grain size control layer having a layer thickness of 2 nm. Next, the 12% by mass concentration composition for orientation control layer prepared above was applied on the crystal grain size control layer by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. Subsequently, after drying and pre-baking by heating at 200 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. And crystallized to obtain an orientation control layer having a layer thickness of 75 nm. Next, the above-prepared composition for a film thickness adjusting layer having a concentration of 12% by mass was applied on the orientation control layer by spin coating under the conditions of 500 rpm for 3 seconds and then 2000 rpm for 20 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-firing four times, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer. A film thickness adjusting layer having a thickness of 300 nm was obtained. This was designated as the ferroelectric thin film of Example 13.

<Example 14>
A substrate similar to that in Example 1 was prepared, and on the Pt lower electrode film of this substrate, the above prepared 2% by weight crystal grains were prepared by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. A composition for a diameter control layer was applied. Subsequently, using a hot plate, heating and drying at 200 ° C. for 5 minutes in an air atmosphere were performed, followed by drying and pre-baking to obtain a crystal grain size control layer having a layer thickness of 5 nm. Next, the 12% by mass concentration composition for orientation control layer prepared above was applied on the crystal grain size control layer by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. Subsequently, after drying and pre-baking by heating at 200 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. And crystallized to obtain an orientation control layer having a layer thickness of 75 nm. Next, the above-prepared composition for a film thickness adjusting layer having a concentration of 12% by mass was applied on the orientation control layer by spin coating under the conditions of 500 rpm for 3 seconds and then 2000 rpm for 20 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-firing four times, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer. A film thickness adjusting layer having a thickness of 300 nm was obtained. This was designated as the ferroelectric thin film of Example 14.

<Example 15>
A substrate similar to that in Example 1 was prepared, and the 1% by mass concentration crystal grains prepared above were formed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. A composition for a diameter control layer was applied. Subsequently, using a hot plate, heating and drying at 200 ° C. for 5 minutes in an air atmosphere were performed, followed by drying and pre-baking to obtain a crystal grain size control layer having a layer thickness of 2 nm. Next, the 12% by mass concentration composition for orientation control layer prepared above was applied on the crystal grain size control layer by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. Subsequently, using a hot plate, drying and pre-baking were performed by heating at 200 ° C. for 5 minutes in an air atmosphere. After repeating the steps of applying the composition for orientation control layer and pre-firing twice, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer thickness. A 150 nm orientation control layer was obtained. Next, the above-prepared composition for a film thickness adjusting layer having a concentration of 12% by mass was applied on the orientation control layer by spin coating under the conditions of 500 rpm for 3 seconds and then 2000 rpm for 20 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-firing four times, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer. A film thickness adjusting layer having a thickness of 300 nm was obtained. This was designated as the ferroelectric thin film of Example 15.

<Example 16>
A substrate similar to that in Example 1 was prepared, and the 1% by mass concentration crystal grains prepared above were formed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. A composition for a diameter control layer was applied. Subsequently, using a hot plate, heating and drying at 200 ° C. for 5 minutes in an air atmosphere were performed, followed by drying and pre-baking to obtain a crystal grain size control layer having a layer thickness of 2 nm. Next, the 12% by mass concentration composition for orientation control layer prepared above was applied on the crystal grain size control layer by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. Subsequently, after drying and pre-baking by heating at 200 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. And crystallized to obtain an orientation control layer having a layer thickness of 75 nm. Next, the above-prepared composition for a film thickness adjusting layer having a concentration of 12% by mass was applied on the orientation control layer by spin coating under the conditions of 500 rpm for 3 seconds and then 2000 rpm for 20 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-baking four times, the film was crystallized by performing main baking at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. After repeating the process of application | coating of the said film thickness adjustment layer composition and temporary baking 4 times, this baking was once performed, this process was repeated 10 times, and the film thickness adjustment layer with a layer thickness of 3000 nm was obtained. This was designated as the ferroelectric thin film of Example 16.

<Example 17>
A substrate similar to that of Example 1 was prepared, and the 1% by mass concentration crystal grains prepared above were formed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. A composition for a diameter control layer was applied. Subsequently, using a hot plate, heating and drying at 200 ° C. for 5 minutes in an air atmosphere were performed, followed by drying and pre-baking to obtain a crystal grain size control layer having a layer thickness of 2 nm. Next, the 10% by mass composition for orientation control layer prepared above was applied onto the crystal grain size control layer by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. Subsequently, after drying and pre-baking by heating at 200 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. This was crystallized to obtain an orientation control layer having a layer thickness of 45 nm. Next, on the orientation control layer, the above-prepared composition for a film thickness adjusting layer having a concentration of 10% by mass was applied by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-baking 6 times, the film was crystallized by performing main baking at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second, A film thickness adjusting layer having a thickness of 270 nm was obtained. This was designated as the ferroelectric thin film of Example 17.

<Example 18>
A substrate similar to that of Example 1 was prepared, and the 1% by mass concentration crystal grains prepared above were formed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. A composition for a diameter control layer was applied. Subsequently, using a hot plate, heating and drying at 200 ° C. for 5 minutes in an air atmosphere were performed, followed by drying and pre-baking to obtain a crystal grain size control layer having a layer thickness of 2 nm. Next, the 10% by mass composition for orientation control layer prepared above was applied onto the crystal grain size control layer by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. Subsequently, using a hot plate, drying and pre-baking were performed by heating at 200 ° C. for 5 minutes in an air atmosphere. After repeating the steps of applying the composition for orientation control layer and pre-firing twice, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer thickness. A 90 nm orientation control layer was obtained. Next, on the orientation control layer, the above-prepared composition for a film thickness adjusting layer having a concentration of 10% by mass was applied by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-baking 6 times, the film was crystallized by performing main baking at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second, A film thickness adjusting layer having a thickness of 270 nm was obtained. This was designated as the ferroelectric thin film of Example 18.

<Example 19>
A substrate similar to that in Example 1 was prepared, and the 1% by mass concentration crystal grains prepared above were formed on the Pt lower electrode film of the substrate by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 15 seconds. A composition for a diameter control layer was applied. Subsequently, using a hot plate, heating and drying at 250 ° C. for 5 minutes in an air atmosphere were carried out for drying and pre-baking to obtain a crystal grain size control layer having a layer thickness of 2 nm. Next, the above-prepared composition for 12 mass% orientation control layer was applied onto the crystal grain size control layer by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. Subsequently, after drying and pre-baking by heating at 250 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a heating rate of 10 ° C./second. This was crystallized to obtain an orientation control layer having a layer thickness of 60 nm. This was designated as the ferroelectric thin film of Example 19.

<Example 20>
A substrate similar to that in Example 1 was prepared, and the 1% by mass concentration crystal grains prepared above were formed on the Pt lower electrode film of the substrate by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 15 seconds. A composition for a diameter control layer was applied. Subsequently, using a hot plate, heating and drying at 300 ° C. for 5 minutes in an air atmosphere were performed for drying and pre-baking to obtain a crystal grain size control layer having a layer thickness of 2 nm. Next, the above-prepared composition for 12 mass% orientation control layer was applied onto the crystal grain size control layer by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. Subsequently, after drying and pre-baking by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second. This was crystallized to obtain an orientation control layer having a layer thickness of 60 nm. This was designated as the ferroelectric thin film of Example 20.

<Comparative Example 1>
A substrate similar to that of Example 1 was prepared, and the 5% by mass concentration of crystal grains prepared above was formed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. A composition for a diameter control layer was applied. Subsequently, using a hot plate, heating and drying at 200 ° C. for 5 minutes in an air atmosphere were performed, followed by drying and pre-baking to obtain a crystal grain size control layer having a layer thickness of 2 nm. Subsequently, the 5 mass% composition for orientation control layer prepared above was applied on the crystal grain size control layer by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. Subsequently, using a hot plate, drying and pre-baking were performed by heating at 200 ° C. for 5 minutes in an air atmosphere. After repeating the steps of applying the composition for orientation control layer and pre-firing twice, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer thickness. A 20 nm alignment control layer was obtained. Next, the above-prepared composition for a film thickness adjusting layer having a concentration of 12% by mass was applied on the orientation control layer by spin coating under the conditions of 500 rpm for 3 seconds and then 2000 rpm for 20 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-firing four times, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer. A film thickness adjusting layer having a thickness of 300 nm was obtained. This was used as the ferroelectric thin film of Comparative Example 1.

<Comparative example 2>
A substrate similar to that in Example 1 was prepared, and the above prepared 11 mass% concentration control was performed on the Pt lower electrode film of the substrate by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. The layer composition was applied. Subsequently, using a hot plate, drying and pre-baking were performed by heating at 200 ° C. for 5 minutes in an air atmosphere. After performing the steps of applying the composition for orientation control layer and pre-firing three times, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer thickness A 170 nm orientation control layer was obtained. This was used as the ferroelectric thin film of Comparative Example 2.

<Comparative Example 3>
A substrate similar to that of Example 1 was prepared, and the above prepared 10 mass% concentration control was performed on the Pt lower electrode film of the substrate by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. The layer composition was applied. Subsequently, using a hot plate, drying and pre-baking were performed by heating at 200 ° C. for 5 minutes in an air atmosphere. After repeating the steps of applying the composition for orientation control layer and pre-firing six times, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer thickness. A 270 nm orientation control layer was obtained. This was a ferroelectric thin film.

<Comparison test>
About the ferroelectric thin film obtained in Examples 1-20 and Comparative Examples 1-3, the layer thickness of each layer, the priority orientation surface, the orientation degree, and the average particle diameter were calculated | required with the following methods. The results are shown in Tables 3 and 4, respectively. Further, the XRD patterns of Examples 1 , 2 , 5 , 6 , 9 , 9 , 12, 13 , 15, 16 , 16 , and 20 are shown in FIG. 3, and the XRD patterns of Comparative Examples 1 to 3 are shown in FIG. 5 shows a surface SEM image (magnification 10,000 times) of FIG. 5, and FIG. 6 shows a surface SEM image (magnification 50,000 times) of Example 6. FIG.
(1) Measurement of layer thickness (film thickness): The thickness of each layer was determined by measuring a ferroelectric thin film with a spectroscopic ellipsometer (JA Woollam Co., Ltd .: M-2000). “Total thickness of orientation control layer”, “layer thickness of orientation control layer”, and “layer thickness of film thickness adjusting layer” were determined. The “layer thickness of the crystal grain size control layer” was calculated by subtracting the “layer thickness of the orientation control layer” from the “total thickness of the crystal grain size control layer and the orientation control layer”.
(2) Preferential orientation plane: The preferential orientation plane of the dielectric crystal is determined by measuring the ferroelectric thin film with an X-ray diffractometer (XRD; manufactured by Bruker: MXP18HF), and has the highest intensity among the obtained diffraction results. The orientation plane was designated as the preferential orientation plane.
(3) Degree of orientation: The degree of orientation in the (100) plane of the dielectric crystal is determined from the diffraction result obtained in (2) above: (100) plane strength / ((100) plane strength + (110) plane) (Intensity + (111) plane strength)).
(4) Average particle size: The average particle size of the dielectric crystal is obtained by photographing the surface of the ferroelectric thin film with a scanning electron microscope (SEM; manufactured by HITACHI: S-900) and showing it in an electron micrograph (surface image). For 30 arbitrary crystal particles, the particle size (longest diameter and shortest diameter) of the crystal particles was measured using calipers, and the average particle diameter was calculated from these measurement results.

  As is clear from Tables 3 and 4 and FIGS. 3 and 4, in Examples 1 to 20 in which the thickness of the orientation control layer was in the range of 30 nm to 150 nm, the degree of orientation was as high as 0.78 to 0.91. Thus, a ferroelectric thin film in which the crystal orientation was preferentially controlled on the (100) plane could be obtained. In Examples 4, 5, 8-11, and 13-18, in which the film thickness adjusting layer is provided, the (100) plane is preferentially crystallized, so that the film thickness adjusting layer is a priority of the orientation control layer. The same crystal orientation plane as the orientation plane is maintained, and the thickness of the ferroelectric thin film whose crystal orientation is preferentially controlled to the (100) plane can be arbitrarily adjusted by this film thickness adjusting layer. It was confirmed that there was.

  On the other hand, in Comparative Example 1 where the thickness of the orientation control layer is 20 nm, the (110) plane is preferentially oriented, and in Comparative Example 2 where the thickness of the orientation control layer is 170 nm, the (111) plane is preferentially oriented. In Comparative Example 3 where the thickness of the orientation control layer was 270 nm, the (111) plane was preferentially oriented.

  As apparent from FIGS. 5 and 6, the crystal grain size control layers of Examples 13 to 20 are compared with the ferroelectric thin film formed without providing the crystal grain size control layers of Examples 2 to 12. It was confirmed that the ferroelectric thin film formed thereon had a crystal structure with a very fine average particle diameter in the outermost layer.

In the production method of the present invention, a ferroelectric thin film preferentially crystallized on the (100) plane can be easily obtained without providing a seed layer or a buffer layer, and the obtained (100) plane preferred orientation is obtained. Pb-containing perovskite ferroelectric thin films such as PZT films have a large e ₃₁ piezoelectric constant and can be used for MEMS applications such as actuators, sensors, gyros, inkjet heads, and autofocus.

10 Substrate 11 Lower electrode 12 Crystal grain size control layer 13 Orientation control layer (underlayer)
14 Thickness adjustment layer

The present invention relates to a method for easily producing a PZT ferroelectric thin film whose crystal orientation is preferentially controlled in the (100) plane.

An object of the present invention is to produce a PZT ferroelectric thin film having an orientation control layer preferentially crystallized in the (100) plane with a fine crystal structure by suppressing the abnormal grain growth of crystals in the orientation control layer. Is to provide.

Another object of the present invention is to provide a PZT ferroelectric thin film capable of arbitrarily adjusting the film thickness of a ferroelectric thin film whose crystal orientation is preferentially controlled on the (100) plane according to the application. It is to provide a manufacturing method.

As shown in FIG. 2, the first aspect of the present invention is a first ferroelectric containing a Pb compound and a Ti compound on the lower electrode of a substrate having a lower electrode whose crystal plane is oriented in the (111) axis direction. A body thin film forming composition is applied and calcined to form a crystal grain size control layer having a layer thickness of 1 nm to 10 nm. A Pb compound, a Zr compound, and a Ti compound are included on the crystal grain size control layer . (2) A composition for forming a ferroelectric thin film is applied, calcined, and then fired to form an orientation control layer, and the coating amount of the second ferroelectric thin film formation composition is crystallized in the orientation control layer. The subsequent layer thickness is set in the range of 45 nm to 150 nm so that the preferential crystal orientation of the orientation control layer is the (100) plane , and the average particle size in the outermost layer is 0.14 or less. It is characterized by a range .

The second aspect of the present invention is an invention based on the first viewpoint, applying a portion of the second ferroelectric thin film-forming composition on the crystal grain diameter control layer 12, calcination, After forming the orientation control layer 13 by firing, the rest of the composition for forming the second ferroelectric thin film is applied on the orientation control layer 13, calcined, and fired to obtain the same crystal orientation as the crystal orientation of the orientation control layer 13. It is characterized by forming a film thickness adjusting layer 14 having

In the first aspect of the present invention, a first ferroelectric thin film forming composition containing a Pb compound and a Ti compound is applied on a lower electrode of a substrate having a lower electrode whose crystal plane is oriented in the (111) axial direction. And calcining to form a crystal grain size control layer having a layer thickness of 1 nm to 10 nm, and a composition for forming a second ferroelectric thin film comprising a Pb compound, a Zr compound and a Ti compound on the crystal grain size control layer After the product is applied and calcined, it is baked to form an orientation control layer, and the coating thickness of the second ferroelectric thin film forming composition is 45 nm to 150 nm after crystallization of the orientation control layer. The preferential crystal orientation of the orientation control layer is set to the (100) plane , and the average particle diameter in the outermost layer is set to a range of 0.14 or less . Thus, after forming the crystal grain size control layer, by providing the orientation control layer on the crystal grain size control layer, abnormal grain growth of the crystals in the orientation control layer can be suppressed. As a result, the orientation control is controlled. The layer can be preferentially crystallized in the (100) plane with a fine crystal structure.

Next, an embodiment for carrying out the present invention will be described with reference to the drawings.
In the present invention, as shown in FIG. 2, a ferroelectric thin film forming composition is applied on a lower electrode 11 of a substrate 10 having a lower electrode 11 whose crystal plane is oriented in the (111) axis direction, and heated. This is an improvement of a method of manufacturing a PZT ferroelectric thin film (hereinafter simply referred to as “ferroelectric thin film”) 13 on the lower electrode 11 by crystallization.

A characteristic configuration of the present invention is that a first ferroelectric thin film forming composition containing a Pb compound and a Ti compound is applied onto the lower electrode 11 and calcined to obtain a crystal grain size control layer having a thickness of 1 nm to 10 nm. 12 is formed, the Pb compound on the grain size control layer 12 is coated with a second ferroelectric thin film-forming composition comprising a Zr compound and Ti compound, after calcination, the orientation control layer by firing And setting the coating amount of the second ferroelectric thin film forming composition so that the layer thickness after crystallization of the orientation control layer 13 is in the range of 45 nm to 150 nm. The crystal orientation is the (100) plane , and the average particle diameter in the outermost layer is in the range of 0.14 or less . Thus, the PZT ferroelectric thin film whose crystal orientation is preferentially controlled on the (100) plane is obtained by setting the thickness of the orientation control layer 13 to be formed after crystallization within the range of 45 nm to 150 nm. It can be easily obtained without providing a seed layer or a buffer layer. Thus, by setting the layer thickness after crystallization within the above range, the resulting orientation control layer 13 can be preferentially crystallized in the (100) plane so that the surface energy is minimized. This is probably due to self-orientation. The layer thickness of the orientation control layer 13 after crystallization is 45 nm to 150 nm. If it is less than 45 nm, it is not preferable because other orientations such as (110) orientation are obtained, and if it exceeds 150 nm, other orientations are similarly undesirable. More preferably, it is 45 nm-90 nm. The reason for this preferable range is that if the temperature range is less than 45 nm, the optimum temperature range of the calcining conditions is narrow and it is difficult to stably obtain (100) orientation. This is because it becomes narrower. Further, by forming an orientation control layer on the crystal grain size control layer 12 after forming the crystal grain size control layer 12, the generation density of nuclei can be increased, so that abnormal grain growth of crystals in the orientation control layer 13 can be achieved. As a result, it is possible to obtain the orientation control layer 13 having a fine crystal structure and crystal orientation preferentially in the (100) plane.

As the substrate 10 for manufacturing the ferroelectric thin film, a heat resistant substrate such as a silicon substrate or a sapphire substrate is used. Further, as the lower electrode 11 in which the crystal plane formed on the substrate 10 is oriented in the (111) axis direction, a material having conductivity such as Pt, Ir, Ru, etc., which does not react with the ferroelectric thin film is used. . Ferroelectric thin film manufacturing is P ZT Ru Pb containing perovskite oxide der.

The composite metal oxide raw material is preferably a compound in which an organic group is bonded to each metal element of Pb , Zr, and Ti via an oxygen or nitrogen atom. For example, one kind selected from the group consisting of metal alkoxide, metal diol complex, metal triol complex, metal carboxylate, metal β-diketonate complex, metal β-diketoester complex, metal β-iminoketo complex, and metal amino complex Or 2 or more types are illustrated. Particularly suitable compounds are metal alkoxides, partial hydrolysates thereof, and organic acid salts. Among them, as a Pb compound, acetate (lead acetate: Pb (OAc) _2), lead diisopropoxide: Pb (OiPr) _2, etc. can be mentioned. As the Ti compound, titanium tetraethoxide: Ti (OEt) ₄ , titanium tetraisopropoxide: Ti (OiPr) ₄ , titanium tetra n-butoxide: Ti (OiBu) ₄ , titanium tetraisobutoxide: Ti (OiBu) ₄ And alkoxides such as titanium tetra-t-butoxide: Ti (OtBu) ₄ and titanium dimethoxydiisopropoxide: Ti (OMe) ₂ (OiPr) ₂ . The Zr compound is preferably an alkoxide similar to the Ti compound. Although the metal alkoxide may be used as it is, a partially hydrolyzed product thereof may be used in order to promote decomposition.

<Example 11>
A substrate similar to that in Example 1 was prepared, and the above prepared 12 mass% concentration control was performed on the Pt lower electrode film of this substrate by spin coating at 500 rpm for 3 seconds and then at 2000 rpm for 20 seconds. The layer composition was applied. Subsequently, after drying and pre-baking by heating at 175 ° C. for 5 minutes in an air atmosphere using a hot plate, main baking is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a heating rate of 10 ° C./second. This was crystallized to obtain an orientation control layer having a layer thickness of 60 nm . Next, the composition for film thickness adjusting layer having a concentration of 10% by mass prepared above was applied on the orientation control layer by spin coating under conditions of 3000 rpm for 15 seconds. Subsequently, drying and pre-baking were performed by heating at 300 ° C. for 5 minutes in an air atmosphere using a hot plate. After repeating the steps of applying the film thickness adjusting layer composition and pre-baking 6 times, the film was crystallized by performing main baking at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second, A film thickness adjusting layer having a thickness of 270 nm was obtained. This was designated as the ferroelectric thin film of Example 11.

<Comparative example 2>
A substrate similar to that in Example 1 was prepared, and the above prepared 11 mass% concentration control was performed on the Pt lower electrode film of the substrate by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. The layer composition was applied. Subsequently, using a hot plate, drying and pre-baking were performed by heating at 200 ° C. for 5 minutes in an air atmosphere. After performing the steps of applying the composition for orientation control layer and pre-firing three times, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer thickness A 170 nm orientation control layer was obtained. No film thickness adjusting layer was formed on this orientation control layer. This was used as the ferroelectric thin film of Comparative Example 2.

<Comparative Example 3>
A substrate similar to that of Example 1 was prepared, and the above prepared 10 mass% concentration control was performed on the Pt lower electrode film of the substrate by spin coating at 500 rpm for 3 seconds and then at 3000 rpm for 20 seconds. The layer composition was applied. Subsequently, using a hot plate, drying and pre-baking were performed by heating at 200 ° C. for 5 minutes in an air atmosphere. After repeating the steps of applying the composition for orientation control layer and pre-firing six times, the main calcination is performed by heating at 700 ° C. for 1 minute in an oxygen atmosphere at a temperature rising rate of 10 ° C./second to crystallize the layer thickness. A 270 nm orientation control layer was obtained. No film thickness adjusting layer was formed on this orientation control layer. This was used as the ferroelectric thin film of Comparative Example 3 .

As apparent from FIGS. 5 and 6, the crystal grain size control layers of Examples 12 to 20 are compared with the ferroelectric thin film formed without providing the crystal grain size control layers of Examples 1 to 11. It was confirmed that the ferroelectric thin film formed thereon had a crystal structure with a very fine average particle diameter in the outermost layer.

Claims (8)

The composition for forming a ferroelectric thin film is applied on the lower electrode of the substrate having the lower electrode with the crystal plane oriented in the (111) axis direction, calcined, and then fired to crystallize the lower electrode. In a method of manufacturing a ferroelectric thin film on an electrode,
The ferroelectric thin film forming composition is applied on the lower electrode and calcined to form a crystal grain size control layer having a layer thickness of 1 nm to 10 nm, and the ferroelectric material is formed on the crystal grain size control layer. After applying and calcining the thin film forming composition , firing to form an orientation control layer,
The application amount of the composition for forming a ferroelectric thin film is set so that the layer thickness after crystallization of the orientation control layer is in the range of 35 nm to 150 nm, and the preferential crystal orientation of the orientation control layer is ( 100) A method for producing a ferroelectric thin film, characterized in that the surface is a plane. The method for producing a ferroelectric thin film according to claim 1, wherein a calcination temperature for forming the crystal grain size control layer is in a range of 175 ° C to 315 ° C. A portion of the composition for forming a ferroelectric thin film is applied on the lower electrode, calcined, and baked to form an orientation control layer, and then the remainder of the composition for forming a ferroelectric thin film is transferred to the orientation control layer. The method for producing a ferroelectric thin film according to claim 1 or 2 , wherein a film thickness adjusting layer having the same crystal orientation as that of the orientation control layer is formed by coating, calcining and firing. 4. The ferroelectric thin film according to claim 3 , wherein a calcining temperature for forming the film thickness adjusting layer after applying the remainder of the composition for forming a ferroelectric thin film is in a range of 200 ° C. to 450 ° C. 5. Production method. The ferroelectric thin film is a Pb-containing perovskite oxide, according to the ferroelectric thin film-forming composition β- diketones and one of claims 4 or claims 1 contains a polyhydric alcohol A method of manufacturing a ferroelectric thin film. The method for producing a ferroelectric thin film according to claim 5, wherein the β-diketone is acetylacetone and the polyhydric alcohol is propylene glycol. It claims 1 to ferroelectric thin film crystal orientation preferentially to the (100) plane produced by the method according to any of the preceding paragraphs. A thin film capacitor having a ferroelectric thin film according to claim 7 , a capacitor, an IPD, a DRAM memory capacitor, a multilayer capacitor, a gate insulator of a transistor, a nonvolatile memory, a pyroelectric infrared detection element, a piezoelectric element, an electro-optical element, Composite electronic parts of actuators, resonators, ultrasonic motors, or LC noise filter elements.