JP2003277310A - METHOD FOR PRODUCING HIGHLY PURE beta-DIKETONATE COMPLEX OF ALKALINE-EARTH METAL AND HIGHLY PURE beta-DIKETONATE COMPLEX FOR FORMING THIN FILM BY CHEMICAL VAPOR DEPOSITION METHOD - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce a highly pure β-diketonate complex of an alkaline-earth metal useful as a raw material for forming thin layers by CVD (chemical vapor deposition) method. <P>SOLUTION: The method for producing the highly pure β-diketonate complex of the alkaline-earth metal is to mix an acetone solution of DPM (dipivaloylmethane) with an acetone solution of BaCl<SB>2</SB>, drop a methanol solution of NaOH under sufficient agitation and react DPM with Ba. Highly pure Ba(DPM)<SB>2</SB>containing <0.01% evaporation of impurities and ≥99.5% evaporation of chelates detected by thermogravimetric analysis in vacuum as shown in figure 1 (C), and having 99.1-101.0% carbon content based on the theoretical value, 99.0-101.0% hydrogen content based on the theoretical value measured by elementary analysis and 99.0-101.0% metal content based on the theoretical value detected by ICP (Inductively-Coupled Plasmaspectrometer) analysis is obtained. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a conventional method useful as a raw material for forming a thin layer such as an oxide containing an alkaline earth metal by a chemical vapor deposition method (hereinafter abbreviated as a CVD method). High-purity alkaline earth metal β-diketonate complex and method for producing the same.

[0002]

2. Description of the Related Art In recent years, the CVD method has come to be used as a promising means for producing oxide-based ceramic thin films or layered ceramics, and the research and development thereof have been actively conducted. For example, the CVD method is used in the manufacturing process of superconductor thin films, dielectric thin films, and various integrated circuits. A β-diketonate metal complex is often used as the raw material. Regarding β-diketonate metal complexes, it has been used for a long time in the analysis of trace metals by gas chromatography, in the studies of stereochemistry and isomer chemistry in metal complexes, ligand exchange, weak nucleophilic reagent interaction, etc. Is also considered to be used as an anti-knock agent for gasoline and as a catalyst for carbon removal in internal combustion engines (RESievers; Science, 201 (1978) pp. 217-223).

Since the β-diketonate metal complex has a relatively high vapor pressure and is highly reactive, it is highly useful as a raw material for CVD. Regarding the usefulness of the β-diketonate metal complex as a raw material for the CVD method, the effect of the metal species forming the complex on the properties of the complex and R
Ligands R ₁ complex represented by _{1 -CO-CH 2 -CO-R} 2
And the influence of R ₂ type have been analyzed and clarified by thermogravimetric analysis (hereinafter abbreviated as TG) curve and vapor pressure data (T.Ozawa: Volatility of
Metal β-Diketonates for Chemical Vapor Deposition
of Oxide of Supercoductor Thermochimica Acta, 174
(1991) 185-199). Further, in order to obtain a good thin film with good reproducibility by the CVD method, it is necessary to use a high-purity raw material, but with respect to the purity of the β-diketonate metal complex, a differential thermal analysis (hereinafter abbreviated as DTA). ) Can be evaluated by a curve.

Alkaline earth metal is an important metal element as a constituent element of oxide type superconductors (for example, Y-Ba-Cu oxide superconductors) and strong and high dielectric materials. As a method for producing the β-diketonate complex of
Several methods are conventionally known. For example, as a typical method, there is a method in which a reactive basic reagent such as ammonia or sodium hydroxide is dropped in an aqueous solution of an alkaline earth metal halide such as chloride to react with β-diketone. However, the β-diketonate metal complex is generally susceptible to deterioration under the influence of moisture and carbon dioxide in the air. Therefore, in the above method, there is a drawback that dehydration is extremely difficult in the process since it passes through an aqueous solution, and a complex of high purity cannot be formed due to the influence of water. Also,
Even by the production method via an aqueous solution, the amount of chelate vaporization can be improved to some extent by paying attention to the removal of impurities such as recrystallization in methanol, but only those containing impurities were obtained. For example, dipivaloylmethane (hereinafter referred to as DPM) ((CH ₃ ) ₃ · C · CO · CH ₂ · CO · C.
(CH ₃ ) ₃ ) is a typical β-diketone, and its alkaline earth metal complex was produced by a conventional method of passing through an aqueous solution and recrystallized in methanol. The obtained Ba (DPM) ₂ was evaluated by TG (under argon atmospheric pressure). As a result, as shown in FIG. 1 (B ′), the chelate evaporation amount was 92%, and the impurity evaporation amount and evaporation residue were The amount was also recognized. When a raw material containing impurities is used in the CVD method as described above, reproducibility is poor and it is difficult to obtain a good thin film.

Further, the β-diketonate metal complex has a problem that it is deteriorated or deteriorated due to moisture in the air or carbon dioxide gas when it is stored in a bad state or stored for a long period of time, resulting in deterioration in performance. For example, solid Ba (DP
M) ₂ was taken out from the storage state and was heated and evaporated at 400 ° C. under an atmospheric pressure of argon using a TG apparatus,
90% was evaporated leaving 10% residue. This one
When placed in a glass screw cap sample bottle and stored at room temperature for 1 month and then subjected to an evaporation test in the same manner, 54% volatilized and 46% remained as a residue, resulting in remarkable deterioration. Also, a slight change in volatility was observed during setting the sample in the TG device. When good results cannot be obtained by using such an unstable raw material in the CVD method, it may not be clear whether the raw material is the cause or the operation of the CVD method is the cause. Therefore, at present, the β-diketonate metal complex of an alkaline earth metal is still unreliable as a raw material for the CVD method, and there are many problems in its production method and storage method.

Further, there is a problem in the evaluation method of the evaporation characteristic of the complex under atmospheric pressure which is usually performed. In general, β-diketonate metal complexes have been conventionally evaluated by TG in an inert gas such as argon under atmospheric pressure, and the results are also described in various catalogs. On the other hand, when the β-diketonate metal complex is actually used in the CVD method, a method is used in which the β-diketonate metal complex is vaporized under a reduced pressure of about 10 Torr, and is carried by a carrier gas for reaction. As described above, since the vaporization conditions in the evaluation and the CVD method are different from each other, the evaluation result under the atmospheric pressure often does not always reflect the result when the CVD method is used. For example, in the case of Ba (DPM) ₂ shown in FIG.
TG under argon gas atmospheric pressure (temperature rising rate: 10 ° C / m
in), the evaporation start temperature was 260 ° C and the evaporation end temperature was 420 ° C. However, in an actual CVD apparatus, the evaporation is generally performed under a reduced pressure of 10 Torr, and the evaporation is performed at a lower temperature of 220 ° C. Further, even if a residue remains in TG at 400 ° C. under an atmospheric pressure of argon, the residue may not always remain in an actual CVD method apparatus. This is because TG under atmospheric pressure is exposed to an excessively high temperature, so that decomposition of the complex or the like may occur and an evaporation residue component may be generated during the test. As described above, the conventional evaluation method is simple for grasping the qualitative tendency of the complex, but the evaluation method of the raw material for the CVD method is an excessive evaluation method that does not fit the actual situation.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation as described above, and has established a suitable method for evaluating volatility and has a high purity alkaline earth metal containing substantially no impurities. The object of the present invention is to provide a β-diketonate complex of and a method for producing the same.

[0008]

In order to solve the above-mentioned problems, the method for producing a highly pure β-diketonate complex of an alkaline earth metal of the present invention comprises adding a basic reaction promoter in an organic solvent, It is for reacting an alkaline earth metal with a β-diketone.

The present invention also provides a high-purity β-diketonate complex for thin film formation by the CVD method manufactured by the above-mentioned manufacturing method.

[0010]

The alkaline earth metal β-diketonate complex of the present invention has a high purity of substantially 100%.
It is useful as a raw material for the CVD method and can be used to obtain a good thin film. The method for producing a high-purity β-diketonate complex of an alkaline earth metal of the present invention, by using an organic solvent, it is possible to produce a high-purity β-diketonate complex of an alkaline earth metal without going through an aqueous solution, and thus a high purity Complex is obtained.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described in detail below.
First, the evaluation method of the β-diketonate metal complex in the present invention will be described. In the present invention, the high-purity complex is evaluated by using the vacuum TG method in which TG is performed under a vacuum close to the conditions of the actual CVD method. In the present invention, vacuum means 1
A state of Torr or lower. When TG under vacuum was tried for Ba (DPM) ₂ shown in FIG. 1 (B ′) as a conventional example, as shown in FIG. 1 (B), the evaporation temperature was significantly shifted to the low temperature side. The result of doing is obtained. Figure 1
In (B), the evaporation start temperature was 190 ° C., the evaporation end temperature was 300 ° C., and the evaporation residue was also reduced. Thus, since the vacuum TG method is close to the conditions of the actual CVD method, the obtained results show the validity of the conditions of the CVD method (220 ° C.), and also for setting the conditions of the CVD method. It is recognized that it is useful as a guideline for using the complex by suggesting that it is effective.

Next, the high-purity β-diketonate metal complex of an alkaline earth metal of the present invention and a method for producing the same will be described by using Ba as an example of the alkaline earth metal and DPM as an example of the β-diketone. . As the organic solvent used in the production method of the present invention, there are n-hexane, benzene, xylene, ether, acetone and the like, which are sufficiently dehydrated before use. First, the alkaline earth metal chlorides BaCl ₂ and DPM are dissolved in an organic solvent such as xylene, and then these solutions are mixed. Then, the target complex is synthesized in an anhydrous state by dropping an alcohol solution such as potassium hydroxide or sodium hydroxide as a reactive basic reagent.

B obtained by the production method of the present invention
FIG. 1C shows the result of evaluation by a vacuum TG method on a (DPM) ₂ , and FIG. 2C shows the result of evaluation by DTA. Here, for comparison, a vacuum TG of Ba (DPM) ₂ obtained by a conventional manufacturing method via an aqueous solution is used.
The curve and the DAT curve are shown in FIG. 1 (A) and FIG. 2 (A), respectively. As described above, FIG. 1 (B) is a vacuum TG curve of Ba (DPM) ₂ obtained by manufacturing the conventional aqueous solution and recrystallizing it in ethanol. The DTA curve of DPM) ₂ is shown in FIG.

As shown in FIG. 1 (C), the Ba (DPM) ₂ obtained by the production method of the present invention has substantially no impurity evaporation amount and no evaporation residue, and is substantially 100% complex. there were. In addition, as shown in the DTA curve of FIG. 2 (C), this Ba (DPM) ₂ was extremely high purity with no peak observed at 200 ° C. or lower. Furthermore, as a result of elemental analysis of the obtained complex, Ba (DP
Of the constituent elements of M) ₂ , the contents of carbon (C) and hydrogen (H) are all 99.0 to 101.
It became 0%, and as a result of ICP analysis, barium (Ba)
Content was 99.0 to 101.0% of the theoretical amount, which was substantially equal to the theoretical amount.

On the other hand, as shown in FIG. 1 (A), Ba (DP) obtained by the conventional method of passing an aqueous solution is used.
In M) ₂ , the chelate evaporation amount was about 85% in the TG curve, and the impurity evaporation amount and evaporation residue were recognized.
Then, as shown in FIG. 2A, an endothermic peak corresponding to the melting point of the complex was observed at about 217 ° C. in the DTA curve, and a complex impurity peak was observed at 200 ° C. or lower. Further, by paying attention to the removal of impurities such as recrystallization of the product obtained by the method of passing through such an aqueous solution, the chelate evaporation amount is 95% as shown in FIG. 1 (B). Although it could be improved to some extent, as shown in FIG. 2B, a slight impurity peak was observed at 200 ° C. or lower.

The high-purity Ba (DPM) _{2 of the} present invention is also used.
Can also be obtained by the following manufacturing method. First, DP
By adding an alkaline earth metal to the xylene solution of M and refluxing for a certain time without using a reactive basic reagent,
The desired complex is directly synthesized. The Ba (DPM) ₂ thus obtained was also a complex of substantially 100%, in which both the amount of impurity evaporation and the evaporation residue were zero in the TG curve. Furthermore, as a result of elemental analysis of the obtained complex,
Among the constituent elements of Ba (DPM) ₂ , the contents of carbon (C) and hydrogen (H) are both theoretical amounts of 99.0 to 1
As a result of ICP analysis, the barium (Ba) content was 99.0 to 101.0% of the theoretical amount, which was substantially equal to the theoretical amount.

In the above description, Ba has been taken as an example.
With respect to other alkaline earth metals other than the above, similarly highly pure β-diketonate complex can be obtained by the production method of the present invention. Furthermore, the β-diketonate complex of an alkaline earth metal is unstable because the TG result may change even if care is taken to store it in a desiccator. Therefore, it is necessary to store the high-purity complex obtained by the present invention without deterioration and use it. For that purpose, the synthesized complex is immediately dissolved in a nucleophilic organic solvent (Japanese Patent Application No. 3-238386) and stored, or the complex is positively coordinated with a nucleophilic organic compound. (Japanese Patent Application No. 3-255592).

[0018]

EXAMPLES Examples of the present invention will be shown below. The organic solvents (acetone, benzene, n-hexane, xylene) used in the following examples were all dehydrated by the following method. An appropriate amount of organic solvent was poured into an Erlenmeyer flask, and subsequently, an appropriate amount of pellets of the molecular sieve degassed at 250 ° C. was added to dehydrate, and then stored in a dry nitrogen gas atmosphere. Further, the dehydrated methyl alcohol was also used.

Example 1 20.0 g of DPM was dissolved in 100 ml of acetone to prepare an acetone solution of DPM. 5.2 g of magnesium chloride (MgCl ₂ ) was added to 100 ml of acetone to prepare an acetone solution of MgCl ₂ . 4.4 g of sodium hydroxide (NaOH) was dissolved in 100 ml of methyl alcohol to prepare a methyl alcohol solution of NaOH. When the acetone solution of DPM and the acetone solution of MgCl ₂ were mixed, and the methyl alcohol solution of NaOH was gradually added dropwise while stirring well, a precipitate mainly composed of sodium chloride (NaCl) was formed. This solution was filtered, the filtrate was concentrated to 70 ml, cooled to −20 ° C., and allowed to stand for 24 hours, whereby a white solid of Mg (DPM) ₂ was deposited. The precipitate was collected by filtration and vacuum dried. The obtained solid was recrystallized in methyl alcohol to obtain highly pure Mg (D
PM) ₂ . The analysis results of the obtained complex are shown below. Vacuum TG Chelate vaporization amount: 99.9% Impurity vaporization amount: 0.00% Elemental analysis C: 67.65% (theoretical amount 67.61 100.1%) H: 9.81% (theoretical amount 9.80 100.1%) ICP analysis Mg: 6.21% (99.8% of theoretical amount 6.22%)

Example 2 50.0 g of DPM was dissolved in 500 ml of benzene to prepare a benzene solution of DPM. 28.3 g of calcium chloride (CaCl ₂ ) was added to 200 ml of benzene to prepare a benzene solution of CaCl ₂ . Sodium hydroxide (NaOH) 15.2g
Was dissolved in 500 ml of methyl alcohol to prepare a methyl alcohol solution of NaOH. The benzene solution of DPM and the benzene solution of CaCl ₂ are mixed,
The above methyl alcohol solution of NaOH was gradually added dropwise with good stirring to form a precipitate mainly containing sodium chloride (NaCl). The solution was filtered, the filtrate was concentrated to 200 ml, cooled to −20 ° C., and allowed to stand for 24 hours, and Ca (DPM) ₂ white solid was precipitated.
The precipitate was collected by filtration and vacuum dried. The obtained solid is recrystallized in methyl alcohol to obtain high-purity Ca.
(DPM) ₂ was obtained. The analysis results of the obtained complex are shown below. Vacuum TG Chelate vaporization amount: 100% Impurity vaporization amount: 0.00% Elemental analysis C: 64.96% (theoretical amount 64.94 100.0%) H: 9.41% (theoretical amount 9.42 99.9%) ICP analysis Ca: 9.85% (theory) 99.9% of the amount 9.86%)

Reference Example 1 42.0 g of DPM was dissolved in 400 ml of n-hexane. To this solution, 10.0 g of metal strontium (Sr) thoroughly washed with n-hexane
Was charged, heated to 69 ° C., and refluxed for 48 hours to obtain a precipitate. The solvent was evaporated and the solid powder obtained by vacuum drying was recrystallized in methyl alcohol to obtain high-purity Sr (DPM).
Got _two . The analysis results of the obtained complex are shown below. Vacuum TG Chelate vaporization amount: 99.9% Impurity vaporization amount: 0.00% Elemental analysis C: 58.20% (100.0% of theoretical amount 58.18) H: 8.46% (100.2% of theoretical amount 8.44) ICP analysis Sr: 19.28% (99.9% of the theoretical amount of 19.28%)

Reference Example 2 27.0 g of DPM was dissolved in 300 ml of xylene. 10.0 g of metal barium (Ba) thoroughly washed with xylene was added to this solution, and 1
The mixture was heated to 39 ° C. and refluxed for 48 hours to obtain a precipitate. The solvent was evaporated, and the solid powder obtained by vacuum drying was recrystallized in methyl alcohol to obtain high-purity Ba (DPM) ₂ .
The analysis results of the obtained complex are shown below. Vacuum TG Chelate vaporization amount: 99.9% Impurity vaporization amount: 0.00% Elemental analysis C: 52.46% (100.0% of theoretical amount 52.44) H: 7.61% (100.1% of theoretical amount 7.60) ICP analysis Ba: 27.25% (100.0% of theoretical 27.26%)

Comparative Example 1 DPM and an aqueous barium chloride solution were mixed, and potassium hydroxide was added dropwise while stirring the solution to obtain a white precipitate. The precipitate was filtered, washed with water, and recrystallized in methanol to obtain Ba (DPM) ₂ . The analysis results of the obtained complex are shown below. Vacuum TG Chelate vaporization amount: 95% Impurity vaporization amount: 2% Elemental analysis C: 50.7% (96.8% of theoretical amount 52.44) H: 7.4% (97% of theoretical amount 7.60) ICP analysis Ba: 28.2% (theoretical amount 27.26) % 103%)

[0024]

Since the production method of the present invention does not pass through an aqueous solution, a highly pure β-diketonate complex of an alkaline earth metal can be obtained without being affected by moisture during the production process. The β-diketonate complex of an alkaline earth metal of the present invention is a highly pure substance which is recognized to be substantially 100% by vacuum TG and elemental analysis, and therefore, it is CVD
It is extremely reliable as a raw material for law. Therefore, when the alkaline earth metal β-diketonate complex of the present invention is used as a raw material for the CVD method, it is possible to prevent film formation defects due to variations in raw material quality, and obtain a good thin film stably. be able to.

[Brief description of drawings]

FIG. 1 is a graph showing a TG curve of a β-diketonate complex of an alkaline earth metal.

FIG. 2 is a graph showing a DTA curve of a β-diketonate complex of an alkaline earth metal.

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 4H006 AA02 AC41 BB11 BB14 BB16                       BE10 BE62                 4H048 AA02 AC41 BB11 BB14 BB16                       BE10 BE61 VA60 VB10                 4K030 AA11 BA42

Claims (2)

[Claims] 1. A method for producing a highly pure β-diketonate complex of an alkaline earth metal, which comprises reacting an alkaline earth metal with a β-diketone by adding a reactive basic reagent in an organic solvent. . 2. A high-purity β-for forming a thin film by the chemical vapor deposition method (CVD method) produced by the method according to claim 1.
Diketonate complex.