JP2010206152A - Composition for ferroelectric thin film formation, method for ferroelectric thin film formation, and ferroelectric thin film formed by the method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for ferroelectric thin film formation that can have both characteristics of reduction in leakage current and improvement in breakdown voltage improved in a well-balanced state and is suitable for use in a thin film capacitor with high capacity density, to provide a method for ferroelectric thin film formation, and to provide a ferroelectric thin film formed by the method. <P>SOLUTION: The composition for ferroelectric thin film formation is used in the formation of the ferroelectric thin film of one material selected from the group consisting of PLZT, PZT and PT. The composition for ferroelectric thin film formation is a liquid composition for the formation of a thin film of a mixed composite metal oxide formed of a mixture of a composite metal oxide A represented by general formula (Pb<SB>x</SB>La<SB>y</SB>)(Zr<SB>z</SB>Ti<SB>(1-z)</SB>)O<SB>3</SB>(wherein 0.9<x<1.3, 0≤y<0.1, and 0≤z<0.9 are satisfied) with a composite oxide B containing P (phosphorus), and consists of an organic metal compound solution such that the raw material consisting the composite metal oxide A and the raw material constituting the composite oxide B are dissolved in an organic solvent at rates for imparting the metal atom ratio shown by the general formula. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a composition for forming a ferroelectric thin film suitable for use in a thin film capacitor having a high capacity density, a method for forming a ferroelectric thin film, and a ferroelectric thin film formed by the method.

  As a method of manufacturing this type of ferroelectric film, a mixed solution in which each component metal alkoxide or organic acid salt is dissolved in a polar solvent is used. It is generally known to form a dielectric thin film by heating to a temperature equal to or higher than the crystallization temperature and firing (see, for example, Patent Document 1).

  Also, for DRAM and nonvolatile memory applications, after an amorphous or crystalline dielectric film is formed on a semiconductor substrate, impurities are diffused into the dielectric film by techniques such as thermal diffusion, ion implantation, and ion doping. There is known a method for manufacturing a dielectric element to be doped by (see, for example, Patent Document 2). This Patent Document 2 discloses a PZT film as a metal dielectric film and P (phosphorus) ions as a dopant. Doping P (phosphorus) can improve the memory retention characteristics of a DRAM or a nonvolatile memory having a dielectric capacitor.

  Moreover, when forming a ferroelectric film made of PZT by the sol-gel method as a capacitor for semiconductor memory cells, lead titanium double alkoxide and lead zirconium double alkoxide are produced, and these reaction products are hydrolyzed. Ferroelectric material which polymerizes by condensation reaction, prepares raw material solution, applies this raw material solution, dries this applied raw material solution to form a dry film, and sinters this dry film A method for forming a film is disclosed (for example, see Patent Document 3). In Patent Document 3, in order to suppress fatigue (reduction in residual polarization value) and leakage current due to reversal of applied voltage when using a deposited PZT thin film, a raw material solution such as lanthanum, niobium, or iron is used. It is described that these metal elements may be added. According to Patent Document 3, hydrolysis and condensation reactions of each double alkoxide proceed uniformly, the PZT thin film formed from this sol-gel solution exhibits a smooth surface, a large residual polarization, a small leakage current, etc. Electrical characteristics are sufficient, and required performance can be satisfied.

  Further, as various device applications utilizing electrical or optical properties, in a composition for forming a PLZT ferroelectric thin film, a composite metal compound A represented by PLZT, Bi, Si, Pb, Ge, Sn, Al, Ga, In, Mg, Ca, Sr, Ba, V, Nb, Ta, Sc, Y, Ti, Zr, Hf, Cr, Mn, Fe, Co, Ni, Zn, Cd, Li, Na, and K A liquid composition for forming a composite metal oxide thin film of composite metal oxide B composed of one or more elements selected from among them, and the compound constituting the metal oxide, A composition comprising a solution dissolved in an organic solvent at a ratio that gives a desired metal atomic ratio is known (see, for example, Patent Document 4). In Patent Document 4, by using this composition, crystallization can be performed even at a low temperature of 450 ° C. or lower when forming a ferroelectric thin film.

  Furthermore, a liquid mixture for forming a ferroelectric thin film in which Ca, Sr, or La is added to PZT is disclosed as a nonvolatile memory application (see, for example, Patent Document 5).

JP-A-60-236404 (page 3, lower right column, line 11 to page 4, lower left column, line 10; page 5, upper right column, line 10 to same page, lower left column, line 17) Japanese Patent Laid-Open No. 5-343441 (Claims 3, 4, and 8, paragraphs [0001] and [0065]) JP-A-7-252664 (claims 2, 3, 7, 8, paragraphs [0001], [0035], [0117], [0118]) JP2003-2647A (Claim 1, paragraphs [0001] and [0013]) US Pat. No. 6,203,608 (Field of the Invention, Claim 1)

  As in Patent Document 2, it is possible to improve the memory retention characteristics by doping P (phosphorus) into the dielectric film. However, in Patent Document 2, it is formed after the dielectric film is formed. Since this is a technique of doping P (phosphorus) into the dielectric film, the dopant may become non-uniform in the film or impurities other than the dopant may be introduced, and the film quality of the dielectric film may be deteriorated. Is done. Furthermore, since a plurality of processes such as a heat treatment process is required, the work may be complicated.

  In addition, as described in Patent Documents 3 to 5, techniques for adding various elements to improve the characteristics of the dielectric film have been developed. However, a ferroelectric thin film is considered for use in a high-capacity density thin film capacitor. In such a case, it is necessary to improve both the characteristics of the reduction of the leakage current and the improvement of the withstand voltage in a balanced manner.

  An object of the present invention is a composition for forming a ferroelectric thin film suitable for high-capacity-density thin film capacitor applications, which can improve both the characteristics of reduction of leakage current and improvement of dielectric strength with a simple technique in a balanced manner. Another object is to provide a method for forming a ferroelectric thin film and a ferroelectric thin film formed by the method.

A first aspect of the present invention is a composition for forming a ferroelectric thin film for forming one kind of ferroelectric thin film selected from the group consisting of PLZT, PZT, and PT, and has a general formula: (Pb _x La _{y) (Zr z Ti (1} -z)) O 3 (0.9 <x <1.3,0 ≦ y <0.1,0 ≦ z composite metal oxide represented by <0.9) wherein A liquid composition for forming a thin film in the form of a mixed composite metal oxide in which a composite oxide B containing P (phosphorus) is mixed with A, a raw material for constituting the composite metal oxide A, and The raw material for constituting the composite oxide B is composed of an organometallic compound solution dissolved in an organic solvent at a ratio giving the metal atomic ratio represented by the above general formula.

  A second aspect of the present invention is an invention based on the first aspect, wherein the raw material for constituting the composite metal oxide A further combines an organic group with a metal element via its oxygen or nitrogen atom. It is characterized by being a compound.

  A third aspect of the present invention is an invention based on the second aspect, wherein the raw material for constituting the composite metal oxide A is a metal alkoxide, a metal diol complex, a metal triol complex, a metal carboxylate, It is one or more selected from the group consisting of metal β-diketonate complexes, metal β-diketoester complexes, metal β-iminoketo complexes, and metal amino complexes.

  A fourth aspect of the present invention is the invention based on the first aspect, wherein the raw material for constituting the composite oxide B is an organic group and a P (phosphorus) element via its oxygen or nitrogen atom. It is a compound which has couple | bonded.

  The fifth aspect of the present invention is the invention based on the fourth aspect, wherein the raw materials for constituting the composite oxide B are alkoxide compounds, diol compounds, triol compounds, carboxylate compounds, β-diketonates. It is 1 type, or 2 or more types chosen from the group which consists of a compound, (beta) -diketoester compound, (beta) -iminoketo compound, and an amino compound, It is characterized by the above-mentioned.

  A sixth aspect of the present invention is an invention based on the first to fifth aspects, further comprising β-diketone, β-ketone acid, β-ketoester, oxyacid, diol, triol, higher carboxylic acid, alkanolamine And further containing one or more stabilizers selected from the group consisting of polyamines in a proportion of 0.2 to 3 moles relative to 1 mole of the total amount of metals in the composition. Features.

  A seventh aspect of the present invention is the invention based on the first to sixth aspects, wherein the molar ratio B / A between B and A is 0 <B / A <0.2. To do.

  An eighth aspect of the present invention is the invention based on the seventh aspect, wherein the molar ratio B / A between B and A is 0.003 ≦ B / A ≦ 0.1. .

  According to a ninth aspect of the present invention, there is provided a step of applying the ferroelectric thin film forming composition according to the first to eighth aspects to a heat resistant substrate and heating in air, an oxidizing atmosphere or a steam-containing atmosphere. It is a method for forming a ferroelectric thin film characterized in that it is repeated once or until a film having a desired thickness is obtained, and the film is fired at a temperature equal to or higher than the crystallization temperature at least after heating in the final step.

  A tenth aspect of the present invention is a ferroelectric thin film formed by a method based on the ninth aspect.

  An eleventh aspect of the present invention is a thin film capacitor having a ferroelectric thin film based on the tenth aspect, a capacitor, an IPD (Integrated Passive Device), a DRAM memory capacitor, a multilayer capacitor, a gate insulator of a transistor, and a nonvolatile memory , A pyroelectric infrared detecting element, a piezoelectric element, an electro-optical element, an actuator, a resonator, an ultrasonic motor, or an LC noise filter element.

  A twelfth aspect of the present invention is a thin film capacitor having a ferroelectric thin film, a capacitor, an IPD, a DRAM memory capacitor, a multilayer capacitor, and a gate insulator of a transistor, corresponding to a frequency band of 100 MHz or more based on the eleventh aspect. , A composite electronic component of a nonvolatile memory, a pyroelectric infrared detection element, a piezoelectric element, an electro-optical element, an actuator, a resonator, an ultrasonic motor, or an LC noise filter element.

The composition for forming a ferroelectric thin film of the present invention has a general formula: (Pb _x La _y ) (Zr _z Ti _(1-z) ) O ₃ (where 0.9 <x <1.3, 0 ≦ y <0.1, 0 ≦ z <0.9), and an organic metal such that the mixed metal oxide A is mixed with the mixed oxide B containing P (phosphorus). A raw material for constituting the composite metal oxide A and a raw material for constituting the composite oxide B are dissolved in an organic solvent in a predetermined ratio in the compound solution. By forming a ferroelectric thin film using this composition, a ferroelectric thin film suitable for high-capacity density thin-film capacitor applications with a balanced improvement in both leakage current reduction and dielectric breakdown voltage improvement can be easily obtained. There is an advantage that it can be obtained by a technique.

It is a figure which shows the relationship between the leakage current density at the time of 5V application in an Example and a comparative example, and P (phosphorus) addition amount. It is a figure which shows the relationship between the leakage current density at the time of 20V application in an Example and a comparative example, and the addition amount of P (phosphorus). It is a figure which shows the relationship between the leakage current density at the time of 50V application in an Example and a comparative example, and the addition amount of P (phosphorus). It is a figure which shows the relationship between the withstand voltage in an Example and a comparative example, and P (phosphorus) addition amount.

  Next, the form for implementing this invention is demonstrated.

The composition for forming a ferroelectric thin film of the present invention is a composition for forming one kind of ferroelectric thin film selected from the group consisting of PLZT, PZT and PT. A ferroelectric thin film formed using this composition has a general formula: (Pb _x La _y ) (Zr _z Ti _(1-z) ) O ₃ (where 0.9 <x <1.3, 0 It takes the form of mixed composite metal oxide in which composite oxide B containing P (phosphorus) is mixed with composite metal oxide A represented by ≦ y <0.1, 0 ≦ z <0.9). In the above equation, when y ≠ 0 and z ≠ 0, it is PLZT, when y = 0 and z ≠ 0, it is PZT, and when y = 0 and z = 0, it is PT. This composition is dissolved in an organic solvent in such a ratio that the raw material for constituting the composite metal oxide A and the raw material for constituting the composite oxide B give the metal atomic ratio represented by the above general formula. An organometallic compound solution.

  As the raw material for the composite metal oxide A, 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 thereof is preferable. 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, examples of the Pb compound and La compound include organic acid salts such as acetates (lead acetate and lanthanum acetate) and alkoxides such as lead diisopropoxide. Examples of the Ti compound include alkoxides such as titanium tetraethoxide, titanium tetraisopropoxide, titanium tetrabutoxide, and titanium dimethoxydiisopropoxide. 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.

  The raw material for the composite oxide B is preferably a compound in which an organic group is bonded to the P (phosphorus) element via the oxygen or nitrogen atom. Examples include one or more selected from the group consisting of alkoxide compounds, diol compounds, triol compounds, carboxylate compounds, β-diketonate compounds, β-diketo ester compounds, β-iminoketo compounds, and amino compounds. Is done. Particularly suitable compounds are alkoxide compounds and partial hydrolysates thereof.

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

  The molar ratio B / A between B and A is adjusted to be in the range of 0 <B / A <0.2. If it is within the above range, both the characteristics of the ferroelectric thin film, which is the effect of the present invention, which is the reduction of leakage current and the improvement of the withstand voltage, can be improved in a balanced manner. If the upper limit value is exceeded, there will be a problem of deterioration of the relative dielectric constant. Among these, 0.003 ≦ B / A ≦ 0.1 is particularly preferable.

  The solvent for the composition for forming a ferroelectric thin film used here is appropriately determined according to the raw material to be used. Generally, carboxylic acid, alcohol, ester, ketones (for example, acetone, methyl ethyl ketone), ether (E.g., dimethyl ether, diethyl ether), cycloalkanes (e.g., cyclohexane, cyclohexanol), aromatics (e.g., benzene, toluene, xylene), other tetrahydrofuran, or a mixture of two or more of these be able to.

  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 weight 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).

  In the present invention, 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) per 1 mL of the solution. It is preferable to be 50 / mL or less.

  A light scattering particle counter is used for measuring the number of particles in the organometallic compound solution.

  If the number of particles having a particle size of 0.5 μm or more in the organometallic compound solution exceeds 50 particles / mL, the long-term storage stability becomes poor. 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.

  By using the composition for forming a ferroelectric thin film of the present invention, a composite oxide B containing P (phosphorus) is mixed with one composite metal oxide A selected from the group consisting of PLZT, PZT and PT. It is possible to easily form a ferroelectric thin film in the form of a mixed composite metal oxide.

  In order to form a ferroelectric thin film by using the composition for forming a ferroelectric thin film of the present invention, the composition is heat-resistant by a coating method such as spin coating, dip coating, or LSMCD (Liquid Source Misted Chemical Deposition). It apply | coats on a board | substrate and performs drying (temporary baking) and main baking.

As a specific example of the heat-resistant substrate to be used, a single crystal Si, polycrystalline Si, Pt, Pt (uppermost layer) / Ti, Pt (uppermost layer) / Ta, Ru, RuO ₂ , Ru ( Top layer) / RuO ₂ , RuO ₂ (top layer) / Ru, Ir, IrO ₂ , Ir (top layer) / IrO ₂ , Pt (top layer) / Ir, Pt (top layer) / IrO ₂ , SrRuO ₃ or _{(La x Sr (1-x} )) is a substrate with CoO ₃ perovskite-type conductive oxide such like, but not limited thereto.

  In addition, when a desired film thickness cannot be obtained by one application, the application and drying steps are repeated a plurality of times, followed by firing. Here, the desired film thickness refers to the thickness of the ferroelectric thin film obtained after the main firing, and in the case of a high capacity density thin film capacitor, the film thickness of the ferroelectric thin film after the main firing is 50 to 500 nm. Range.

  In addition, pre-baking is performed in order to remove the solvent and thermally decompose or hydrolyze the organic metal compound or organic compound to convert it into a composite oxide. Therefore, in the air, in an oxidizing atmosphere, or in a steam-containing atmosphere. Do. 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 or organic compound.

The main firing is a step for firing and crystallizing the thin film obtained by the pre-firing at a temperature equal to or 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.

  The pre-baking is performed at 150 to 550 ° C. for about 1 to 30 minutes, and the main baking is performed at 450 to 800 ° C. for about 1 to 10 minutes. The main baking may be performed by rapid heating treatment (RTA treatment). When the main baking is performed by the RTA treatment, the heating rate is preferably 10 to 100 ° C./second.

  The ferroelectric thin film of the present invention formed as described above has a balanced improvement in both the reduction of leakage current and the improvement of the withstand voltage, and has excellent basic characteristics as a capacitor and a high capacity density thin film. Suitable for capacitor applications. The ferroelectric thin film of the present invention is also excellent in basic characteristics as an IPD.

  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. Among these, it can also be used especially for the thing corresponding to the frequency band of 100 MHz or more.

  Next, examples of the present invention will be described in detail together with comparative examples.

  In the following examples and comparative examples, the following materials were used as raw materials.

Pb compound: lead acetate trihydrate La compound: lanthanum acetate hemihydrate Zr compound: zirconium tetra t-butoxide Ti compound: titanium tetraisopropoxide P (phosphorus) compound: P (phosphorus) triisopropoxide , Triethyl phosphate <Examples 1 to 29, Comparative Examples 1 to 8>
As the organic solvent, 2-methoxyethanol that had been sufficiently dehydrated was used, and an organic metal compound (Pb, La compound, etc.) in the form of an organic acid salt was dissolved therein, and crystal water was removed by azeotropic distillation. Thereafter, an alkoxide-form organometallic compound or organic compound (Zr, Ti, P (phosphorus) compound, etc.) is added and dissolved in the resulting solution, and acetylacetone or diethanolamine is doubled with respect to the alkoxide for solution stabilization A solution for forming a thin film was prepared in which the total concentration of the organometallic compound was about 10% by weight in terms of metal oxide so that the added element species and addition amount shown in the following Table 1 or 2 were added to PZT. .

  Using each solution, a thin film was formed by the CSD method by the following method.

  That is, each solution was applied on a 6-inch silicon substrate on which a Pt thin film was formed on the surface by a sputtering method at 500 rpm for 3 seconds by a spin coating method and then at 3000 rpm for 15 seconds.

  Subsequently, using a hot plate, it was heated at 350 ° C. for 10 minutes to perform preliminary firing. This coating and pre-baking process is repeated 6 times, and then the film is baked in a 100% oxygen atmosphere or dry air atmosphere at 700 ° C. for 1 minute by RTA (rapid heat treatment apparatus) to form a 300 nm-thick ferroelectric thin film. did.

After that, using a metal mask, a Pt upper electrode of about 250 μm □ is formed on the surface by sputtering, and a DC voltage is applied between the Pt lower electrodes immediately below the ferroelectric thin film to obtain IV characteristics (leakage current density). Voltage dependence and dielectric strength). The IV characteristics were measured using a 236 SMU manufactured by Keithley under the conditions of bias step 0.5 V, delay time 0.1 sec, temperature 23 ° C., and hygrometry 50 ± 10%. The definition of “insulation breakdown voltage” is a voltage at the previous Bias step where the leakage current density exceeds 1 A / cm ² . The results are shown in the following Tables 1 and 2 and FIGS.

表１及び図１〜図４から明らかなように、Ｐ（燐）を含まない比較例１の強誘電体薄膜に比べて、Ｐ（燐）を添加した実施例１〜５の強誘電体薄膜では、リーク電流密度の低減と同時に絶縁耐圧の向上が確認された。

As apparent from Table 1 and FIGS. 1 to 4, the ferroelectric thin films of Examples 1 to 5 to which P (phosphorus) is added as compared with the ferroelectric thin film of Comparative Example 1 that does not contain P (phosphorus). Then, it was confirmed that the withstand voltage was improved simultaneously with the reduction of the leakage current density.

  Further, the same tendency was shown in the comparison between the ferroelectric thin films of Comparative Examples 2 and 3 containing La and the ferroelectric thin films of Examples 11 to 13 containing P (phosphorus) simultaneously with La.

  From Comparative Example 1 and Comparative Example 4, when Sn is added, the leakage current density increases. However, as shown in Examples 6 to 8, when P (phosphorus) coexists, the leakage current density is similarly reduced and insulated. The improvement effect of pressure resistance was confirmed.

  In addition, from the results of the ferroelectric thin films of Examples 6 to 10, the good effect of P (phosphorus) can be confirmed even if other components such as Sn and Si coexist with about 1% simultaneously with P (phosphorus). It was confirmed that P (phosphorus) is an additive element that greatly affects the characteristics.

  Further, from the results of the ferroelectric thin films of Examples 14 to 19, 20 to 25 and Comparative Examples 5 and 6, the leakage current density was reduced regardless of the added P (phosphorus) compound form, the type of stabilizer, and the firing atmosphere. And withstand voltage can be improved at the same time.

  Furthermore, from the results of the ferroelectric thin films of Examples 26 to 29 and Comparative Examples 7 and 8, the same good tendency was confirmed even in the presence of La.

  From these results, the ferroelectric thin films of Examples 1 to 29 have an excellent effect on leakage withstand voltage and withstand voltage, and can be made thin, so that high capacity density can be achieved.

  The composition for forming a ferroelectric thin film of the present invention, the method for forming a ferroelectric thin film, and the ferroelectric thin film formed by the method are excellent in basic characteristics as a capacitor, and are used for a high-capacity density thin film capacitor. Is available. In addition, it has excellent basic characteristics as an IPD. IPD, DRAM memory capacitor, multilayer capacitor, transistor gate insulator, nonvolatile memory, pyroelectric infrared detector, piezoelectric element, electro-optical element, actuator, resonator It can be used for composite electronic parts such as ultrasonic motors or LC noise filter elements.

Claims (12)

In the ferroelectric thin film forming composition for forming one kind of ferroelectric thin film selected from the group consisting of PLZT, PZT and PT,
General formula: (Pb _x La _y ) (Zr _z Ti _(1-z) ) O ₃ (where 0.9 <x <1.3, 0 ≦ y <0.1, 0 ≦ z <0.9) A liquid composition for forming a thin film in the form of a mixed composite metal oxide in which a composite oxide B containing P (phosphorus) is mixed with the composite metal oxide A represented by
An organic metal dissolved in an organic solvent in such a ratio that the raw material for constituting the composite metal oxide A and the raw material for constituting the composite oxide B give a metal atomic ratio represented by the above general formula A composition for forming a ferroelectric thin film comprising a compound solution.   2. The composition for forming a ferroelectric thin film according to claim 1, wherein the raw material for constituting the composite metal oxide A is a compound in which an organic group is bonded to a metal element via its oxygen or nitrogen atom.   The raw materials for constituting the composite metal oxide A are metal alkoxide, metal diol complex, metal triol complex, metal carboxylate, metal β-diketonate complex, metal β-diketoester complex, metal β-iminoketo complex, and metal 3. The composition for forming a ferroelectric thin film according to claim 2, wherein the composition is one or more selected from the group consisting of amino complexes.   2. The composition for forming a ferroelectric thin film according to claim 1, wherein the raw material for constituting the composite oxide B is a compound in which an organic group is bonded to a P (phosphorus) element via its oxygen or nitrogen atom.   The raw material for constituting the composite oxide B is selected from the group consisting of alkoxide compounds, diol compounds, triol compounds, carboxylate compounds, β-diketonate compounds, β-diketoester compounds, β-iminoketo compounds, and amino compounds. The composition for forming a ferroelectric thin film according to claim 4, wherein the composition is one kind or two or more kinds.   Composition of one or more stabilizers selected from the group consisting of β-diketone, β-ketone acid, β-ketoester, oxyacid, diol, triol, higher carboxylic acid, alkanolamine and polyvalent amine The composition for forming a ferroelectric thin film according to any one of claims 1 to 5, further comprising 0.2 to 3 moles per mole of the total amount of metals in the product.   The composition for forming a ferroelectric thin film according to any one of claims 1 to 6, wherein a molar ratio B / A between B and A is 0 <B / A <0.2.   The composition for forming a ferroelectric thin film according to claim 7, wherein the molar ratio B / A between B and A is 0.003 ≦ B / A ≦ 0.1.   A process of applying the composition for forming a ferroelectric thin film according to any one of claims 1 to 8 to a heat resistant substrate and heating in air, in an oxidizing atmosphere or in a steam-containing atmosphere once or in a desired manner A method for forming a ferroelectric thin film, which is repeated until a film having a thickness is obtained, and the film is fired at a temperature equal to or higher than a crystallization temperature at least after heating in the final step.   A ferroelectric thin film formed by the method according to claim 9.   A thin film capacitor having a ferroelectric thin film according to claim 10, a capacitor, an IPD, a DRAM memory capacitor, a multilayer capacitor, a gate insulator of a transistor, a nonvolatile memory, a pyroelectric infrared detecting element, a piezoelectric element, an electro-optical element, Composite electronic parts of actuators, resonators, ultrasonic motors, or LC noise filter elements.   A thin film capacitor having a ferroelectric thin film, a capacitor, an IPD, a capacitor for DRAM memory, a multilayer capacitor, a gate insulator of a transistor, a nonvolatile memory, a pyroelectric infrared, corresponding to a frequency band of 100 MHz or more according to claim 11 A composite electronic component including a detection element, a piezoelectric element, an electro-optical element, an actuator, a resonator, an ultrasonic motor, or an LC noise filter element.

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