JPH0790594A - Coating solution for forming titanium based multiple oxide - Google Patents

Abstract

PURPOSE:To form a multiple oxide film using a coating solution more excellent in preservation stability compared with the conventional one and capable of giving prescribed thickness by means of a single coating on a substrate. CONSTITUTION:This coating solution for forming titanium based multiple oxide is composed of (A) a reactional product of tetra-alkoxy titanium with hydroxy acid and (B) an organic solvent based solution containing a water soluble salt of a metal except titanium. If necessary, a soluble polymer is blended thereinto.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stable coating liquid for forming a titanium-based composite oxide. More specifically, the present invention forms a titanium-based composite oxide film having dielectric, piezoelectric, pyroelectric, electrostrictive, and electro-optical properties on a substrate made of silicon, glass, ceramics, metal or the like. The present invention relates to a stable coating solution used for.

[0002]

2. Description of the Related Art A titanium-based composite oxide is BaTiO 3.
₃System, Pb (Fe, W) O₃-Pb (Fe, Nb) O
₃System, Pb (Ni, Nb) O₃-Pb (Mg, W) O₃−
PbTiO₃System, Pb (Mg, Nb) O₃-Pb (Ni,
Nb) O₃-PbTiO₃System, Ba₂, Ti ₉O₂₀System, (Z
r, Sn) TiO_FourSystem, MgTiO₃-CaTiO₃system,
MgO-TiO₂-La₂O₃-CaO system, (Sr, C
a) [(Li, Nb) Ti] O₃System, BaO / Sm₂O₃
・ 5TiO₂System, BaO-PbO-Nd₂O₃-TiO₂system
As a dielectric of₃System, PbTiO₃-PbZ
rO₃System, PbTiO₃-PbZrO₃-Pb (Mg, N
b) O₃As a piezoelectric material of the system, or BaTiO 3₃System, S
rTiO₃Widely used as dielectrics, piezoelectrics, varistors, etc.
It is widely used. By utilizing the physical properties unique to them,
Sonic cleaning, condenser pick-up oscillator, communication fill
Switch, sound wave delay circuit, high voltage generating transformer, infrared sensor
Electronic elements such as sensors and ignition elements, various electro-optical materials
It is used for materials and superconducting materials.

By the way, in order to form a titanium-based composite oxide on a substrate, P and P on a substrate together with a titanium compound.
The method of applying a solution containing a metal compound that is a component of a complex oxide such as b, Zr, Sr, Ba, and Mg, and drying and baking is easy to operate and can be applied to a surface having a complicated shape. Recommended.

However, the metal alkoxide generally used as the metal compound in this method is easily hydrolyzed, and decomposes during preparation and storage of the coating solution to precipitate a solid content, which is used. The disadvantage is that the resulting coating is non-uniform.

In order to improve such defects and improve storage stability, an alkoxyl group and β-
Use of an organic metal compound solution having a diketone group (Japanese Patent Laid-Open No. 61-97159) or blending of ethanolamine and alcohol in a solution containing lead alkoxide or lead salt, zirconium alkoxide, titanium alkoxide (special (Kaihei 2-6335) is proposed, but none of them can obtain sufficient storage stability and is not practical.

On the other hand, in the case of forming a complex oxide film that requires a certain thickness, such as a ferroelectric film, on a substrate, the coating liquids used so far are required until the required thickness is obtained. However, it is inevitable that the operation becomes complicated because it is necessary to apply multiple layers. Therefore, there has been a demand for a coating solution for forming a complex oxide that can obtain a desired film thickness by one-time application and firing.

[0007]

Under the circumstances described above, the present invention has sufficiently practical storage stability, and a sufficiently thick film can be obtained by one-time application and firing. The purpose of the present invention is to provide a coating liquid for forming a titanium-based composite oxide that can be obtained.

[0008]

[Means for Solving the Problems] The inventors of the present invention have earnestly studied to develop a coating liquid for forming a titanium-based complex oxide, which has good storage stability and is suitable for obtaining a thick coating film. As a result, by adding titanium alkoxide or its complex compound as a reaction product with an oxyacid together with a soluble salt of other necessary metal, the storage stability is remarkably improved and further soluble in this coating solution. It was found that when a polymer is blended, a thick coating film can be obtained by a single coating, and the present invention has been completed based on this finding.

That is, the present invention provides (a) a reaction product of tetraalkoxytitanium or a complex compound thereof with an oxyacid, (b) a soluble salt of a metal other than titanium as a component of a titanium-based composite oxide, and A coating liquid for forming a titanium-based composite oxide, which further comprises (c) an organic solvent-based solution containing a soluble polymer, is provided.

The component (a) of the present invention is a reaction product of tetraalkoxytitanium or a complex compound thereof and an oxyacid. The tetraalkoxytitanium has the general formula: Ti (OR) ₄ ... I (wherein R is an alkyl group, and each R may be the same or different). Examples of such a compound include tetramethoxy titanium, tetraethoxy titanium, tetrapropoxy titanium, tetrabutoxy titanium, tetrapentoxy titanium, tetrahexoxy titanium, trimethoxyethoxy titanium, dimethoxydiethoxy titanium, dimethoxydipropoxy titanium, and dimethoxy titanium. Examples thereof include ethoxydipropoxytitanium, triethoxybutoxytitanium and diethoxydibutoxytitanium. These tetraalkoxy titaniums may be used alone or in combination of two or more.

In the present invention, a complex compound thereof may be used in place of the above tetraalkoxytitanium, and this complex compound is obtained, for example, by adding a β-diketone compound or a glycol compound to tetraalkoxytitanium. It is a thing. Examples of β-diketones used in this case include acetylacetone, trifluoroacetylacetone, hexafluoroacetylacetone, benzoylacetone, benzoyltrifluoroacetone, dibenzoylmethane, acetoacetic acid methyl ester, acetoacetic acid ethyl ester, acetoacetic acid butyl ester. Esters and the like, and examples of glycol compounds include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, trimethylene glycol, butanediol, hexylene glycol and the like. These may be used alone or in combination of two or more. Further, it may be used as a mixture with tetraalkoxy titanium.

The component (a) used in the coating liquid of the present invention is a reaction product obtained by reacting the above titanium compound or its complex compound with an oxyacid. Examples of the oxyacid include glycolic acid and lactic acid. , Hydroxyacrylic acid, oxybutyric acid, malic acid and the like can be mentioned, with lactic acid being particularly preferred. These oxy acids may be used alone or in combination of two or more.

The reaction of tetraalkoxytitanium or its complex compound with an oxyacid can be carried out, for example, by dissolving tetraalkoxytitanium or its complex compound in a suitable organic solvent, adding an oxyacid thereto, and stirring. At this time, if necessary, the reaction can be promoted by heating.

The amount of the oxy acid used is 0.5 to 2.0 with respect to 1 mol of tetraalkoxy titanium or its complex compound.
It is selected in the range of 0.7 mol to 1 mol, preferably 0.7 to 1.2 mol. The presence of the reaction product is, for example, tetraalkoxytitanium or its complex compound alone does not dissolve in water but precipitates or gels, but a product obtained by contacting these with an oxyacid It can be confirmed from the fact that is soluble in water.

As the component (a) in the present invention, those prepared in advance may be used, but a predetermined amount of an oxy compound is added to an organic solvent containing tetraalkoxytitanium or its complex compound and the component (b) in a predetermined ratio. It is advantageous to add the acid and generate it in situ.

Next, the soluble salt of the metal used as the component (b) in the present invention is a soluble salt of the metal necessary to form a desired titanium-based composite oxide together with titanium. It is possible to arbitrarily select from the metal components of titanium-based composite oxides known up to now, and there is no particular limitation. Examples of such a metal include Pb,
Sr, Ba, Mg, Zn, Sn, Ni, Nb, Zr,
Examples thereof include W, La, Y and Li.

Examples of soluble salts of these metals include, for example,
Ba (CH₃COO)₂nH₂O, La (CH₃COO)₃
nH₂O, Pb (CH₃COO)₂nH₂O, Li (CH₃
COO) nH₂O, Zn (CH₃COO)₂nH₂O, Sr
(CH₃COO)₂nH₂O, Y (CH₃COO)₃nH
₂O, Mg (CH₃COO)₂nH₂Organic carvone such as O
Acid salt, reaction formation of these organic carboxylates with lactic acid
Thing, Ba (NO₃)₂nH₂O, La (NO₃)₃nH₂O,
Pb (NO₃)₂nH₂O, Li (NO₃) NH₂O, Mg
(NO₃)₂nH₂O, Sr (NO₃)₂nH₂O, Zn (N
O₃)₂nH₂O, Y (NO₃)₃nH₂Nitrate such as O, S
r [OCOCH (CH₃) OH]₂・ H₂O, Ba [OC
OCH (CH₃) OH]₂・ H₂O, Li [OCOCH
(CH₃) OH] ₂・ H₂Lactate such as O
However, the coating liquid is not limited to these, and
Any salt that is soluble in the organic solvent used
Can also be used. These soluble salts are
May be used, or two or more kinds may be used in combination.
it can.

The use ratio of the component (a) and the component (b) is
It is determined depending on the atomic ratio of each metal in the desired complex oxide, but is usually within the range of 0.1 to 5 equivalents, preferably 0.2 to 3 equivalents, per total of 1 equivalent of titanium. Is selected in.

In the present invention, the component (a) and the component (b) are dissolved in an organic solvent capable of dissolving them. Examples of such an organic solvent include methyl alcohol and ethyl alcohol. , Isopropyl alcohol, n-propyl alcohol, n-butyl alcohol,
Ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, octylene glycol, diethylene glycol, dipropylene glycol, dihexylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monopropyl ether, ethylene Glycol monophenyl ether, ethylene glycol monobenzyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, ethylene glycol dipropyl Ether, ethylene glycol dibenzyl ether, ethylene glycol methyl ethyl diether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dibutyl ether, methyl carbitol, ethyl carbitol, butyl carbitol, phenyl carbitol, benzyl carbitol, dimethyl Carbitol,
Examples thereof include diethyl carbitol, dibutyl carbitol, diphenyl carbitol, dibenzyl carbitol, methyl ethyl carbitol, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol dibutyl ether, and lactic acid. These organic solvents may be used alone or in combination of two or more.

In the present invention, in addition to these components, in order to facilitate the formation of a thick film, a soluble (particularly) alcohol-soluble polymer may be added as the component (C), if desired. You can Such a soluble polymer has a hydroxyl group in its molecular structure, for example, partially saponified polyvinyl acetate, polyvinyl alcohol, formal resin, butyral resin, polyglycerin, etc., or 2-hydroxymethyl acrylate, 2-hydroxymethyl. Methacrylate, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate,
Mention may be made of homopolymers and copolymers of monomers having hydroxyl groups such as 2-hydroxypropyl methacrylate, 2-hydroxybutyl acrylate and 2-hydroxybutyl methacrylate. In addition, soluble polymers such as polyvinylpyrrolidone can also be used.

These soluble polymers are added in an amount of 1 to 100 parts by weight, preferably 3 to 40 parts by weight, per 100 parts by weight of the total amount of the components (a) and (b) contained in the coating liquid. . If this amount is less than 1 part by weight, it becomes difficult to form a thick coating film by one-time application.
If the amount is more than 100 parts by weight, the physical properties of the titanium-based composite oxide formed will deteriorate.

The coating solution of the present invention is prepared by adding
(A) component and (b) component and (ha) component in some cases,
It is prepared by dissolving and fully dispersing so that the total solid component concentration is in the range of 5 to 50% by weight.

The coating solution of the present invention thus obtained is applied to substrates, metals, semiconductor substrates, etc. obtained by firing powders of plastics, glass, ceramics, metal nitrides, metal carbonates and the like. By heating, it is possible to form a composite metal oxide film which is a ferroelectric film having excellent uniformity. As the coating means in this case, a dipping and pulling method, a spray method, a spin coating method, a brush coating method, a roll coating method, a printing method, a reduced pressure spraying method (L
Any of the SCUD method) can be used.
As heating means, hot plate heating, hot air heating,
Burner heating, infrared heating, laser heating, high frequency heating, rapid heating method (RTA method) and the like can be mentioned. A heating temperature of 250 ° C. or higher, preferably 350 ° C. or higher can form a chemically stable coating film, but it is limited by the material of the substrate, so it must be appropriately selected within a temperature that the substrate can withstand. .

[0024]

The coating liquid of the present invention exhibits extremely excellent storage stability as compared with conventional coating liquids, and its performance does not deteriorate even after storage for a long period of time. Has an advantage that a complex oxide film having a desired film thickness can be easily formed on a substrate. Therefore, it is possible to form a ceramic film having specific electric characteristics such as a ferroelectric film on a substrate. It is suitable as a coating liquid.

[0025]

EXAMPLES The present invention will be described in more detail with reference to examples.

Example 1 500 g of ethylene glycol monomethyl ether and 540 g of lactic acid were uniformly mixed, and 107.36 g (0.5 mol) of strontium acetate hemihydrate and 1 barium acetate were mixed therein.
To the solution obtained by adding 29.7 g (0.5 mol) and reacting for 1 to 2 hours, tetrabutoxy titanium 343.8.
To 168.9 g of a solution obtained by slowly adding 6 g (1 mol) and adding 250 g of ethylene glycol monomethyl ether, and uniformly diluting 0.45 μm.
A coating solution was prepared by applying a filter of m.

Next, the coating solution was applied onto a 3-inch silicon wafer with a spinner at a rotation speed of 2000 rpm to obtain a coating film. And 140 ℃, 300 ℃, 500
A transparent and uniform ferroelectric film having a film thickness of 760 Å could be formed by carrying out a baking treatment at 30 ° C. and 700 ° C. for 30 minutes each.

Further, even when the prepared coating solution was allowed to stand at room temperature for 3 months, no deposits and the like were found in the coating solution.

Example 2 500 g of ethylene glycol monomethyl ether and 360 g of lactic acid were uniformly mixed, and 64.4 g (0.3 mol) of strontium acetate hemihydrate and 17 barium acetate were mixed therein.
To the solution obtained by adding 8.8 g (0.7 mol) and reacting for 1-2 hours, tetrabutoxy titanium 343.86.
g (1 mol) was slowly added and reacted to obtain 144.71 g of a solution, to which 7.2 g of pure water and 275 g of ethylene glycol monomethyl ether were added and uniformly diluted to obtain a coating solution with a 0.45 μm filter. Was prepared.

Next, on a 3-inch silicon wafer,
The coating liquid was applied with a spinner at a rotation speed of 2000 rpm to obtain a coating film. Then, for this coating film, Example 1
As a result of forming a film by the same operation as above, a transparent and uniform ferroelectric film having a film thickness of 750Å was formed. Further, even when this coating solution was allowed to stand at room temperature for 3 months, no deposits and the like were observed in the coating solution.

Example 3 Solution 144 obtained by reacting in the same manner as in Example 144.
To 71 g, 7.2 g of pure water and 250 g of ethylene glycol monomethyl ether were added and uniformly diluted, and 175 g of acetoacetic acid ethyl ester was further added and stirred and reacted. Next, 44.47 g of a 26.3 wt% ethylene glycol monomethyl ether solution of polyhydroxyethyl methacrylate was added to this reaction solution, and the mixture was uniformly mixed and filtered through a 0.45 μm filter to prepare a coating solution.

Next, the coating liquid was applied onto a 3-inch silicon wafer with a spinner at a rotation speed of 2000 rpm to obtain a coating film. Then, for this coating film, Example 1
As a result of forming a film by the same operation as above, a transparent and uniform ferroelectric film having a film thickness of 930Å was formed. Further, even when this coating solution was allowed to stand at room temperature for 3 months, no deposits and the like were observed in the coating solution.

Example 4 300 g of ethylene glycol monomethyl ether, 152.2 g of propylene glycol and 360.32 g of lactic acid were uniformly mixed to obtain 214.7 strontium acetate hemihydrate.
To the solution obtained by adding 2 g (1 mol) and reacting for 1 to 2 hours, 343.86 g (1 mol) of tetrabutoxy titanium, 6.1 g of propylene glycol and 90.08 of lactic acid were added.
After adding a solution consisting of 500 g and uniformly mixing, 500 g of ethylene glycol monomethyl ether and 500 g of propylene glycol were added and uniformly diluted to 0.
A coating solution was prepared by applying a 45 μm filter.

Next, the coating solution was applied onto a 3-inch silicon wafer with a spinner at a rotation speed of 6000 rpm to obtain a coating solution. Then, for this coating film, Example 1
As a result of forming a film by the same operation as above, a transparent and uniform ferroelectric film having a film thickness of 750Å was formed. Further, even when this coating solution was allowed to stand at room temperature for 3 months, no deposits and the like were observed in the coating solution.

Example 5 500 g of ethylene glycol monomethyl ether and 360 g of lactic acid were uniformly mixed, and barium acetate of 255.44 was mixed.
g (1 mol) was added, and the solution obtained by reacting for 1 to 2 hours was added with tetrabutoxy titanium 343.86 g (1 mol).
Was slowly added to cause a reaction, 72 g of pure water and 109.44 g of ethylene glycol monomethyl ether were added to dilute, 600 g of a 19.5 wt% ethylene glycol monomethyl ether solution of polyhydroxypropyl methacrylate was further added, and the mixture was mixed. 0.45μ
A coating solution was prepared by applying a filter of m.

Next, the coating liquid was applied onto a 3-inch silicon wafer with a spinner at a rotation speed of 2000 rpm to obtain a coating film. Then, for this coating film, Example 1
As a result of forming a film by the same operation as above, a transparent and uniform ferroelectric film having a film thickness of 2250 Å was formed. Further, even when this coating solution was allowed to stand at room temperature for 3 months, no deposits and the like were observed in the coating solution.

Example 6 500 g of ethylene glycol monomethyl ether and 360 g of lactic acid were uniformly mixed, and 76.63 g of barium acetate was mixed.
(0.3 mol) and strontium acetate hemihydrate 150.3
g (0.7 mol), and the solution obtained by reacting for 2 to 3 hours had 343.86 g (1
(Mole), and then the solution obtained by adding 100.12 g of acetylacetone was added and uniformly mixed, and then 72 g of pure water
And 1750 g of ethylene glycol monomethyl ether were added, and the mixture was uniformly diluted and filtered through a 0.45 μm filter to prepare a coating solution.

Next, the coating solution was applied onto a 3-inch silicon wafer with a spinner at a rotation speed of 2000 rpm to obtain a coating film. Then, for this coating film, Example 1
As a result of forming a film by the same operation as above, the film is transparent and has a film thickness of 750.
A Å ferroelectric film was formed. Further, even when this coating solution was allowed to stand at room temperature for 3 months, no deposits and the like were observed in the coating solution.

Example 7 To 343.86 g (1 mol) of tetrabutoxy titanium was added 750 g of ethylene glycol monomethyl ether,
To the solution obtained by further adding 180 g of lactic acid, 385 g of acetylacetone, 1500 g of ethylene glycol monomethyl ether, and 646.75 g of bismuth nitrate pentahydrate.
What added the mixed solution with (1.3 mol) was 0.45
A coating solution was prepared by applying a filter of μm.

Then, on a 3 inch silicon wafer,
The coating liquid was applied with a spinner at a rotation speed of 2000 rpm to obtain a coating film. Then, for this coating film, Example 1
As a result of forming a film by the same operation as described above, a transparent and uniform ferroelectric film having a film thickness of 860Å was formed. Further, even when this coating solution was allowed to stand at room temperature for 3 months, no deposits and the like were observed in the coating solution.

Example 8 To 343.86 g (1 mol) of tetrabutoxytitanium was added 76.1 g of propylene glycol, and lactic acid 9 was added.
To the solution obtained by adding 0.08 g, 152.2 g of propylene glycol, 800 g of ethylene glycol monomethyl ether, 360.32 g of lactic acid, 64.40 g (0.3 mol) of strontium acetate hemihydrate and 1 barium acetate.
What added the mixed solution with 78.80g is 0.45μ
A coating solution was prepared by applying a filter of m.

Next, the coating liquid was applied onto a 3-inch silicon wafer with a spinner at a rotation speed of 4000 rpm to obtain a coating film. Then, for this coating film, Example 1
As a result of forming a film by the same operation as above, a transparent and uniform ferroelectric film having a film thickness of 750Å was formed. Further, even when this coating solution was allowed to stand at room temperature for 3 months, no deposits and the like were observed in the coating solution.

Example 9 340 g of TLA (trade name, manufactured by Nippon Soda Co., Ltd.) commercially available as a reaction product of tetraalkoxytitanium and lactic acid was added to 500 g of ethylene glycol monomethyl ether,
Further, 107.36 g of strontium acetate hemihydrate (0.
5 mol) and 129.7 g (0.5 mol) of barium acetate and reacted for 1-2 hours, 250 g of ethylene glycol monomethyl ether was added to the solution, and the solution was applied to a 0.45 μm filter. Was prepared.

Next, the coating liquid was applied onto a 3-inch silicon wafer with a spinner at a rotation speed of 2000 rpm to obtain a coating film. Then, for this coating film, Example 1
As a result of forming a film by the same operation as above, a transparent and uniform ferroelectric film having a film thickness of 750Å was formed. Further, even when this coating solution was allowed to stand at room temperature for 3 months, no deposits and the like were observed in the coating solution.

Example 10 TAA (trade name, manufactured by Nippon Soda Co., Ltd.) 3 which is commercially available as a reaction product of tetrabutoxytitanium and acetylacetone
40 g and ethylene glycol monomethyl ether 500
g and 540 g of lactic acid are uniformly mixed, and 107.36 g (0.5 mol) of strontium acetate and 1 barium acetate are further mixed.
To the solution obtained by adding 29.7 g (0.5 mol) and reacting for 1 to 2 hours, 250 g of ethylene glycol monomethyl ether was added, and the solution was filtered through a 0.45 μm filter to prepare a coating solution.

Then, the coating solution was applied onto a 3-inch silicon wafer with a spinner at a rotation speed of 2000 rpm to obtain a coating film. Then, for this coating film, Example 1
As a result of forming a film by the same operation as above, a transparent and uniform ferroelectric film having a film thickness of 750Å was formed. Further, even when this coating solution was allowed to stand at room temperature for 3 months, no deposits and the like were observed in the coating solution.

Comparative Example 1 A coating solution was prepared in the same manner as in Example 1 except that lactic acid was removed in the preparation of the coating solution of Example 1. The coating solution became cloudy at the time of preparation and a gelled substance was confirmed. However, it cannot be used as a coating liquid for forming a ferroelectric film.

Comparative Example 2 A coating solution was prepared in the same manner as in Example 1 except that lactic acid was removed in the preparation of the coating solution of Example 7, but the coating solution became cloudy at the time of preparation and a gelled substance was confirmed. However, it cannot be used as a coating liquid for forming a ferroelectric film.

Comparative Example 3 A coating solution was prepared in the same manner as in Example 1 except that lactic acid was removed in the preparation of the coating solution of Example 8. The coating solution became cloudy at the time of preparation and a gelled substance was confirmed. However, it cannot be used as a coating liquid for forming a ferroelectric film.

Claims (3)

[Claims] 1. An organic solvent-based material containing (a) a reaction product of tetraalkoxytitanium or a complex compound thereof and an oxyacid, and (b) a soluble salt of a metal other than titanium as a component of a titanium-based composite oxide. A coating liquid for forming a titanium-based composite oxide, which is a solution. 2. The metal as a component of the titanium-based composite oxide is Pb, Sr, Ba, Mg, Zn, Sn, Ni, Nb, Z.
The coating liquid for forming a titanium-based composite oxide according to claim 1, which is at least one selected from r, W, La, Y and Li. 3. The total amount of component (a) and component (b) is 10
The coating liquid for forming a titanium-based complex oxide according to claim 1 or 2, wherein 1 to 100 parts by weight of a soluble polymer is blended per 0 part by weight.