JP2002255557A - Coating solution for forming ferroelectric thin film, method for synthesizing organic metal compound as ferroelectric and method for regulating orientation of ferroelectric thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a coating solution for stable forming a bismuth-lanthanum titanate(BLT) thin film which contains La in the solution, and is formed at a low cost, to provide a method for producing an organic metal compound, to provide a method for producing the coating solution and to provide a method for regulating the orientation in the bismuth-lanthanum titanate(BLT) thin film. SOLUTION: The coating solution far forming the bismuth-lanthanum titanate(BLT) thin film is characterized by containing the organic metal compound in an organic solution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a coating solution for forming a ferroelectric thin film used in a nonvolatile semiconductor memory device.

[0002]

2. Description of the Related Art Ferroelectrics have many functions such as spontaneous polarization, high dielectric constant, electro-optic effect, piezoelectric effect, and pyroelectric effect, and are widely applied to device development. Above all, ferroelectric nonvolatile memories using the thin film have been actively developed.

[0003] Non-volatile memories provided with a ferroelectric thin film, which are currently being studied, employ a method for detecting a change in the amount of charge stored in a ferroelectric capacitor and a method for detecting a change in resistance of a semiconductor due to spontaneous polarization of a ferroelectric. Can be classified into two types. The former has a structure in which the capacitor of the DRAM is replaced with a ferroelectric capacitor, and all of the writing, erasing, and reading operations involve the reversal of the polarization of the ferroelectric, so that the ferroelectric is severely fatigued. In addition, it is necessary to provide a transistor and a capacitor separately, which is disadvantageous for reducing the cell area.

On the other hand, MOS-FETs (Metal Oxide Semic
MF (I) S-FET (Metal Ferroelectrics (Insulato)
r) Semiconductor-FET), MFMIS-FET (Metal Ferroelectr
ics Metal Insulator Semiconductor-FET) and the like have been proposed as ferroelectric memories that are fast and advantageous for area reduction.

However, in the conventional MFIS-FET and MFMIS-FET, the difference in the relative permittivity between the buffer layer (I) and the ferroelectric layer (F) is large, so that an electric field required for polarization reversal is generated in the ferroelectric. It does not take. In addition, the data retention characteristic is degraded by the depolarizing electric field, which is a major obstacle in putting this type of memory into practical use. In order to reduce the depolarization electric field generated in the ferroelectric thin film, it is necessary to form a ferroelectric layer having a low relative dielectric constant and a small leak current.

Conventionally, ferroelectric materials having good ferroelectric properties as a thin film material, especially Sr
Bismuth layered compound (BLS) represented by Bi ₂ Ta ₂ O ₉ (SBT)
F) has attracted attention, but on the other hand, the demand for a material having a lower dielectric constant than SBT has been increasing. Recently, bismuth lanthanum titanate (BL
T) has attracted attention (BHPark et al., Nature vol40
1, p682-684 (1999); JP-A-2000-260960). BLT is the bismuth layered compound bismuth titanate (BIT) Bi
This is a composite oxide partially substituted with a.

[0007] The methods for forming these BLSF thin films include sputtering, MOCVD, laser ablation, and spin coating, and the like. Sputtering, MOCVD, and laser ablation require expensive equipment. ,
It is costly and has difficulties in controlling the composition of the thin film and its application to large-diameter substrates. On the other hand, the spin coating method is considered to be advantageous because a relatively inexpensive apparatus can be used to form a film and the composition control of the thin film is easy.

The formation of a ferroelectric thin film by spin coating is performed in the following steps. An organic metal raw material such as a metal alkoxide and an organic acid salt is mixed in an organic solvent according to a target film composition, and the concentration is adjusted to obtain a coating solution. This is spin-coated on a substrate of glass, sapphire, titanium, platinum or the like, dried, and then crystallized in a rapid infrared heating furnace (RTA).

The generation of the coating solution for forming a ferroelectric thin film is performed in the following steps. An organic metal raw material such as a metal alkoxide and an organic acid salt is mixed in an organic solvent according to a desired film composition, and the concentration is adjusted to obtain a coating solution. A coating solution for forming a BLSF thin film was prepared by reacting bismuth alkoxide, lanthanum alkoxide, and titanium alkoxide in 2-methoxyethanol, and then performing hydrolysis using acetylacetone as a stabilizer and nitric acid as a catalyst to prepare a solution. (The Ceramic Society of Japan 1999
Proceedings of the Annual Meeting, 1A05, p5 (1999)), the lanthanum alkoxide used here is very expensive and therefore has little practical use. The solution contains nitric acid.
It has been reported that bismuth acetate and titanium alkoxide are reacted in a mixed solvent of 2-methoxyethanol acetate to form a coating solution for forming BIT thin films (JJAP, PART 1, VO2).
L.32, No. 9B, 4158-4162 (1993)), there is no description about using a La raw material, that is, BLT. It has been reported that bismuth acetate, lanthanum acetate, and titanium isopropoxide are dissolved in acetic acid to form a coating solution for forming a BLT thin film (Appl. Phys. Lett., Vol. 78, No.
5, 658-660, 29 January 2001), which is a mixture of acetic acid and the above-mentioned raw materials, has poor stability in a solution, has a problem in wettability to a substrate, and further has an odor. There is also a problem in terms of workability.

[0010] Problems of producing a coating solution for forming a BLT thin film include the fact that the La raw material is generally insoluble in an organic solvent, so that solution synthesis is difficult, and precipitation during the formation of the thin film. In the BLT thin film, Bi of bismuth titanate (BIT) is partially replaced by La, and it is a very important issue in synthesizing a solution to surely dissolve the La element in the solution. Further, those containing a large amount of acetic acid have problems in terms of solution stability and workability. Therefore, a solution containing as little acetic acid as possible is desired.

The BLT thin film is characterized in that the polarization anisotropy is very large, the a-axis oriented thin film shows large polarization, and the c-axis oriented thin film shows very small polarization. In the above-mentioned FET type ferroelectric memory, a ferroelectric thin film having a small polarization is preferable in terms of characteristics, while a ferroelectric thin film having a large polarization is preferable in a 1T-1C type memory. In view of the above, a BLT thin film having large polarization anisotropy has attracted attention. Therefore, when applying a BLT thin film to a ferroelectric memory, it is very important to control the orientation of the BLT thin film. Absent.

[0012]

Accordingly, an object of the present invention is to provide a coating solution for forming a bismuth lanthanum titanate (BLT) thin film which can be formed at a low cost by containing La in a solution, a method for producing an organometallic compound, An object of the present invention is to provide a method for producing the coating solution and a method for controlling the orientation of a bismuth lanthanum titanate (BLT) thin film.

[0013]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the method of preparing a coating solution has been described in the step of synthesizing an organometallic compound and the method of converting the organometallic compound into an organic compound. By dividing into two steps of dissolving in a solvent, a method for producing a coating solution for forming a lanthanum ferroelectric thin film, which can be formed at low cost and is stable, has been found, and the present invention has been achieved. That is, the present invention relates to a coating solution for forming a bismuth lanthanum titanate (BLT) thin film, which comprises an organic metal compound in an organic solvent. Further, the present invention is characterized in that the organic solvent comprises 2-methoxyethanol,
The present invention relates to a coating solution for forming a bismuth lanthanum titanate (BLT) thin film. Further, the present invention provides an organic metal compound,
The coating solution for forming a bismuth lanthanum titanate (BLT) thin film, characterized by being obtained by reacting bismuth acetate, lanthanum acetate and titanium alkoxide in an acetic acid-organic solvent mixed solvent. The present invention also relates to the coating solution for forming a bismuth lanthanum titanate (BLT) thin film, wherein the acetic acid-organic solvent mixed solvent is a mixed solvent of acetic acid: organic solvent = 1: 5 to 1: 1 by volume ratio. Furthermore, in the present invention, the organic solvent of the acetic acid-organic solvent mixed solvent is 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 2- (methoxymethoxy) ethanol, and 2- (2
The bismuth lanthanum titanate (BLT), comprising one or more selected from the group consisting of -methoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethanol, ethanol, propanol and butanol. The present invention relates to a coating solution for forming a thin film.

Further, the present invention relates to the coating solution for forming a bismuth lanthanum titanate (BLT) thin film, wherein the organic solvent of the acetic acid-organic solvent mixed solvent contains 2-methoxyethanol. Furthermore, the present invention relates to the coating solution for forming a bismuth lanthanum titanate (BLT) thin film, further comprising water or an inorganic acid aqueous solution. The present invention also relates to the bismuth lanthanum titanate (BLT) coating solution for forming a thin film, comprising a stabilizer. Further, the present invention, the stabilizer is acetylacetone,
Biethanol lanthanum titanate (BLT), which is diethanolamine or triethanolamine.
The present invention relates to a coating solution for forming a thin film.

The present invention also relates to a method for synthesizing an organometallic compound, wherein acetic acid: organic solvent = 1: 5 to 1: 1 by volume ratio.
Wherein bismuth acetate, lanthanum acetate and titanium alkoxide are heated and reacted in a mixed solvent of the above. Further, the present invention, the organic solvent of the acetic acid-organic solvent mixed solvent is 2-methoxyethanol,
2-ethoxyethanol, 2-propoxyethanol,
2-butoxyethanol, 2- (methoxymethoxy) ethanol, 2- (2-methoxyethoxy) ethanol,
The present invention relates to a method for synthesizing the organometallic compound, comprising one or more selected from the group consisting of 2- (2-ethoxyethoxy) ethanol, ethanol, propanol, and butanol. The present invention also relates to the method for synthesizing the organometallic compound, wherein the organic solvent of the acetic acid-organic solvent mixed solvent contains 2-methoxyethanol. Further, the present invention provides a method for producing a coating solution for forming a bismuth lanthanum titanate (BLT) thin film, comprising reacting bismuth acetate, lanthanum acetate and titanium alkoxide in an acetic acid-organic solvent mixed solvent, and concentrating the mixture. The present invention relates to the above method, wherein the reaction solvent is removed, the obtained organometallic compound is isolated, and then the organometallic compound is dissolved in the organic solvent. Also, the present invention provides a bismuth lanthanum titanate (BLT) thin film obtained by performing hydrolysis by adding water or an inorganic acid aqueous solution to a coating solution for forming a bismuth lanthanum titanate (BLT) thin film. Related to the method of controlling.

The bismuth lanthanum titanate of the present invention (BL
T) According to the coating solution for forming a thin film, the acetic acid used for the reaction
The organic metal compound isolated by removing the organic solvent mixed solvent by concentration is dissolved in an organic solvent. The solution itself is stable because it does not contain acetic acid or contains only a small amount of acetic acid. According to the present invention, bismuth acetate, lanthanum acetate and titanium alkoxide are reacted in an acetic acid-organic solvent mixed solvent to obtain an organometallic compound, so that the lanthanum raw material can be dissolved. Since the acetate is used, a coating solution for forming a bismuth lanthanum titanate (BLT) thin film can be produced at low cost. On the other hand, in forming a thin film in the present invention, the orientation of the obtained bismuth lanthanum titanate (BLT) thin film can be controlled by adding a small amount of water or an aqueous solution of an inorganic acid to the coating solution. And can be applied to a wide range of ferroelectric memories.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
An example of the organometallic compound used in the present invention will be described. Examples of the bismuth acetate include bismuth acetate and basic bismuth acetate, with bismuth acetate being preferred.

As lanthanum acetate, lanthanum acetate 1.
Examples thereof include pentahydrate and anhydrous lanthanum acetate, and preferred is lanthanum acetate hemihydrate.

Examples of the titanium alkoxide include titanium tetraalkoxide such as titanium tetramethoxide, titanium tetraethoxide, titanium tetrapropoxide, titanium tetraisopropoxide and titanium tetrabutoxide. Preferably, titanium tetraisopropoxide is used.

As the organic solvent for dissolving the organometallic compound, any organic solvent may be used as long as it can dissolve the organometallic compound. Examples thereof include 2-methoxyethanol, 2-ethoxyethanol and 2-propoxyethanol. 2-butoxyethanol, 2- (methoxymethoxy) ethanol, 2- (2-methoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethanol, ethanol, propanol, butanol, 1-methoxy-2
-Propanol, 1-ethoxy-2-propanol, 1
-Propoxy-2-propanol, 1-butoxy-2-
Examples include, but are not limited to, propanol. These organic solvents may be used alone or in combination of two or more, and may be further mixed with another solvent. Preferably, it is an organic solvent containing 2-methoxyethanol. As the organic solvent used in the acetic acid-organic solvent mixed solvent for obtaining the organometallic compound, any organic solvent may be used as long as it can dissolve bismuth acetate, lanthanum acetate and titanium alkoxide. -Methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 2- (methoxymethoxy) ethanol, 2- (2-methoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethanol, ethanol, propanol , Butanol and the like. These organic solvents may be used alone or as a mixture of two or more. Preferably, it is an organic solvent containing 2-methoxyethanol. The organic solvent for dissolving the organometallic compound and the organic solvent used for the acetic acid-organic solvent mixed solvent for obtaining the organometallic compound may be the same or different.

Next, a method for producing the coating solution of the present invention will be described. An organometallic compound is obtained by reacting the above-mentioned lanthanum acetate, bismuth acetate and titanium alkoxide in an acetic acid-organic solvent mixed solvent. Thereafter, the reaction solvent is removed by concentration or the like, and the organometallic compound is isolated. Then, the organometallic compound is dissolved or reacted in the organic solvent to produce the compound. In addition, this solution can be used as it is, but furthermore, a stabilizer such as acetylacetone, diethanolamine or triethanolamine is added, or if necessary, water or an aqueous solution of an inorganic acid such as nitric acid is added to carry out hydrolysis. You can do it too. The orientation of the bismuth lanthanum titanate (BLT) thin film can be controlled by hydrolysis with water or an aqueous solution of an inorganic acid.

The ratio of the acetic acid-organic solvent mixed solvent for reacting lanthanum acetate, bismuth acetate and titanium alkoxide is used in a volume ratio of acetic acid: organic solvent = 1: 5 to 1: 1, preferably, Acetic acid: organic solvent = 1: 4-
1: 2. The stabilizer can be added in an amount of 0.1 to 5.0 equivalents, preferably 0.1 to 1.0 equivalents, based on the total number of moles of the metal contained in the coating solution. In the case of performing hydrolysis, the amount of water to be added is 0 to 2.0 equivalents, preferably 0 to 1.0 equivalent, relative to the total number of moles of the metal contained in the coating solution. The amount is 0.1 to 10.0 equivalents, with a preferred range of 0.1 to 3.
It is 0 equivalent. Further, the coating solution of the present invention can easily form a thin film having an arbitrary composition ratio by changing the amount of raw materials charged.

The coating solution of the present invention comprises a Pt / SiO ₂ / Si substrate, Pt
A BLT thin film can be formed by spin coating and drying on a / Ti / SiO ₂ / Si substrate or the like, followed by crystallization by firing. Heating methods for drying and firing are hot plate heating, hot air heating using a clean oven, a diffusion furnace, infrared heating, and rapid heating (RTA).
Method).

[0024]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

Example 1 Bismuth acetate 33.5 mmol, lanthanum acetate hemihydrate 7.5 mmol
Acetic acid (100 ml) was added to the mixture, and the mixture was heated at 70 ° C. for 10 minutes to dissolve. After the solution was heated and stirred under reflux for 2 hours, it was distilled and concentrated. After cooling to room temperature, 100 ml of acetic acid was added again, and the mixture was heated and stirred under reflux for 1 hour. Concentration by distillation was performed in the same manner as above, and the mixture was cooled to room temperature. On the other hand, 30 mmol of titanium tetraisopropoxide was dissolved in 150 ml of 2-methoxyethanol, and the mixture was heated and stirred under reflux for 2 hours, and then cooled to room temperature. This solution is added to a mixed solution of bismuth and lanthanum and mixed, and the ratio of the solution is acetic acid: 2-methoxyethanol by volume ratio.
= 1: 3 and then stirred at 80 ° C for 8 hours.
After the reaction, 150 ml of 2-methoxyethanol was added, and the mixture was concentrated under reduced pressure to obtain white crystals. Again, 100 ml of 2-methoxyethanol was added, and concentration under reduced pressure was repeated to obtain white crystals. 2-methoxyethanol was added to the obtained white crystals and dissolved by stirring.
The concentration of this solution was adjusted to 10 wt% in terms of BLT,
Filtration with a 2μm filter, BLT thin film forming coating solution 1 (B
i: La: Ti = 3.35: 0.75: 3.00) was prepared.

Next, the coating solution for forming a thin film is made of Pt / Ti / SiO ₂
The substrate was spin-coated on a / Si substrate at 2500 rpm for 20 seconds, and dried on a hot plate at 150 ° C. for 10 minutes. Thereafter, heat treatment was performed at 400 ° C. for 10 minutes in a rapid infrared heating furnace (RTA). The above steps were repeated until the desired film thickness was obtained. In the present example, this was repeated four times.

Then, a metal film having a diameter of 0.2 mm and a film thickness of 100 nm is formed on the ferroelectric thin film through a metal mask by a metal deposition method.
Form Pt top electrode, and finally, rapid infrared heating furnace (RTA)
Heat treatment was performed in an oxygen atmosphere at 750 ° C. for 20 minutes to form a ferroelectric capacitor. FIG. 1 shows the configuration diagram. The resulting film thickness was about 160 nm. When the X-ray diffraction analysis of the thin film obtained as described above was performed, the X-ray diffraction pattern shown in FIG. 2 was obtained, and it was confirmed that the thin film had a bismuth layered perovskite structure unique to a ferroelectric.

The formed ferroelectric capacitor has an applied voltage of 1.
At 6 V, a hysteresis characteristic was exhibited (FIG. 5). The amount of polarization was 2Pr = 8.4 μC / cm ² .

Example 2 A 10 wt% coating solution 2 for forming a BLT thin film was prepared in the same manner as in Example 1 except that Bi: La: Ti was changed to 3.55: 0.75: 3.0.

Next, the coating solution for forming a thin film is made of Pt / Ti / SiO ₂
The substrate was spin-coated on a / Si substrate at 2500 rpm for 20 seconds, and dried on a hot plate at 150 ° C. for 10 minutes. Thereafter, heat treatment was performed at 400 ° C. for 10 minutes in a rapid infrared heating furnace (RTA). The above steps were repeated until the desired film thickness was obtained. In the present example, this was repeated four times.

Then, a metal film having a diameter of 0.2 mm and a film thickness of 100 nm is formed on the ferroelectric thin film through a metal mask by a metal deposition method.
Form Pt top electrode, and finally, rapid infrared heating furnace (RTA)
Heat treatment was performed in an oxygen atmosphere at 750 ° C. for 20 minutes to form a ferroelectric capacitor. The obtained film thickness was about 162 nm. When the X-ray diffraction analysis of the thin film obtained as described above was performed, the X-ray diffraction pattern shown in FIG. 3 was obtained, and it was confirmed that the thin film had a bismuth layered perovskite structure unique to a ferroelectric. In particular, the orientation to the a-axis preferred orientation (117) was suppressed, and a film oriented to the c-axis could be obtained.

The formed ferroelectric capacitor has an applied voltage of 1.
At 6 V, a hysteresis characteristic was exhibited (FIG. 6). The amount of polarization in this case was 2Pr = 5.2 μC / cm ² , indicating a hysteresis curve with a high squareness ratio. BL with small polarization of c-axis orientation
A T thin film was obtained.

Example 3 0.6 g of a 70% aqueous nitric acid solution was added to the solution obtained in Example 2.
And 10 ml of 2-methoxyethanol were added to prepare a coating solution 3 for forming a BLT thin film.

Next, the coating solution for forming a thin film is made of Pt / Ti / SiO ₂
The substrate was spin-coated on a / Si substrate at 2500 rpm for 20 seconds, and dried on a hot plate at 150 ° C. for 10 minutes. Thereafter, heat treatment was performed at 400 ° C. for 10 minutes in a rapid infrared heating furnace (RTA). The above steps were repeated until the desired film thickness was obtained. In the present example, this was repeated four times.

Then, a metal film having a diameter of 0.2 mm and a film thickness of 100 nm is formed on the ferroelectric thin film via a metal mask by a metal deposition method.
Form Pt top electrode, and finally, rapid infrared heating furnace (RTA)
Heat treatment was performed in an oxygen atmosphere at 750 ° C. for 20 minutes to form a ferroelectric capacitor. The obtained film thickness was about 163 nm. When the X-ray diffraction analysis of the thin film obtained as described above was performed, the X-ray diffraction pattern shown in FIG. 4 was obtained, and it was confirmed that the thin film had a bismuth layered perovskite structure unique to a ferroelectric. It was confirmed that although the film was oriented along the c-axis, the orientation toward the a-axis preferred orientation (117) was larger than that in Example 2.

The formed ferroelectric capacitor has an applied voltage of 1.
At 6 V, it exhibited hysteresis characteristics (FIG. 7). The polarization amount was 2Pr = 19.8 μC / cm ² . By hydrolyzing with nitric acid, a BLT thin film of a-axis preferred orientation with large polarization was obtained.

[0037]

According to the present invention, a stable and inexpensive bismuth lanthanum titanate thin film forming solution can be obtained. By hydrolyzing the solution with water or an inorganic acid aqueous solution, the orientation of the formed thin film can be controlled, so that a thin film suitable for each proposed memory cell structure can be supplied. .

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration example of a ferroelectric capacitor formed using a coating solution for forming a ferroelectric thin film of the present invention.

FIG. 2 is a chart of X-ray diffraction in Example 1.

FIG. 3 is a chart of X-ray diffraction in Example 2.

FIG. 4 is an X-ray diffraction chart in Example 3.

FIG. 5 is a graph showing hysteresis characteristics in Example 1.

FIG. 6 is a graph showing hysteresis characteristics in Example 2.

FIG. 7 is a graph showing hysteresis characteristics in Example 3.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 29/792 F-term (Reference) 4G048 AA03 AB02 AC02 AD02 AE05 AE08 4K022 AA02 AA03 AA04 AA44 BA15 BA22 BA28 BA33 CA13 DA06 DB01 DB19 DB24 EA01 5F083 FR02 FR06 FR07 GA06 GA21 JA12 JA17 PR23 PR34 5F101 BA62 BD02 BH01

Claims (14)

[Claims] A bismuth lanthanum titanate (BL) containing an organic metal compound in an organic solvent.
T) Coating solution for thin film formation. 2. The coating solution for forming a bismuth lanthanum titanate (BLT) thin film according to claim 1, wherein the organic solvent contains 2-methoxyethanol. 3. The method according to claim 1, wherein the organometallic compound is obtained by reacting bismuth acetate, lanthanum acetate and titanium alkoxide in an acetic acid-organic solvent mixed solvent. The coating solution for forming a bismuth lanthanum titanate (BLT) thin film according to the above. 4. The thin film for forming a bismuth lanthanum titanate (BLT) thin film according to claim 3, wherein the acetic acid-organic solvent mixed solvent is a mixed solvent of acetic acid: organic solvent = 1: 5 to 1: 1 by volume ratio. Coating solution. 5. The organic solvent of the acetic acid-organic solvent mixed solvent,
2-methoxyethanol, 2-ethoxyethanol, 2
-Propoxyethanol, 2-butoxyethanol, 2
It contains one or more selected from the group consisting of-(methoxymethoxy) ethanol, 2- (2-methoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethanol, ethanol, propanol and butanol. The coating solution for forming a bismuth lanthanum titanate (BLT) thin film according to any one of claims 1 to 4. 6. The organic solvent of the acetic acid-organic solvent mixed solvent,
The coating solution for forming a bismuth lanthanum titanate (BLT) thin film according to claim 5, comprising 2-methoxyethanol. 7. The coating solution for forming a bismuth lanthanum titanate (BLT) thin film according to claim 1, further comprising water or an aqueous solution of an inorganic acid. 8. The coating solution for forming a bismuth lanthanum titanate (BLT) thin film according to claim 1, further comprising a stabilizer. 9. The bismuth lanthanum titanate (BL) according to claim 8, wherein the stabilizer is acetylacetone, diethanolamine or triethanolamine.
T) Coating solution for thin film formation. 10. A method for synthesizing an organometallic compound, comprising:
The above method, wherein bismuth acetate, lanthanum acetate and titanium alkoxide are heated and reacted in a mixed solvent of acetic acid: organic solvent = 1: 5 to 1: 1 by volume ratio. 11. The organic solvent of the acetic acid-organic solvent mixed solvent is 2-methoxyethanol, 2-ethoxyethanol, 2-propoxyethanol, 2-butoxyethanol, 2- (methoxymethoxy) ethanol, and 2- (2-methoxyethanol).
The organometallic compound according to claim 10, comprising one or more selected from the group consisting of methoxyethoxy) ethanol, 2- (2-ethoxyethoxy) ethanol, ethanol, propanol, and butanol. Synthesis method. 12. The method for synthesizing an organometallic compound according to claim 11, wherein the organic solvent of the acetic acid-organic solvent mixed solvent contains 2-methoxyethanol. 13. A method for producing a coating solution for forming a bismuth lanthanum titanate (BLT) thin film, comprising reacting bismuth acetate, lanthanum acetate and titanium alkoxide in a mixed solvent of acetic acid and an organic solvent, and reacting the mixture by concentration. After removing the solvent and isolating the resulting organometallic compound,
The above method, wherein the organometallic compound is dissolved in an organic solvent. 14. The orientation of a bismuth lanthanum titanate (BLT) thin film obtained by performing hydrolysis by adding water or an inorganic acid aqueous solution to a coating solution for forming a bismuth lanthanum titanate (BLT) thin film, How to control.