TW200536785A - Coating solutions for use in forming bismuth-based paraelectric or ferroelectric thin films, and bismuth-based paraelectric or ferroelectric thin films - Google Patents

Abstract

This invention is to disclose a coating liquid for forming a Bi-based dielectric thin film showing paraelectric or ferroelectric property in compliance with applications of semiconductor memories. This coating liquid for forming a Bi-based dielectric thin film showing paraelectric or ferroelectric property contains a composite metal oxide expressed by the formula: (Bi(4–x), (Laz.B(1–z)x)n(Ti(3–y),Ay)O(12+α) (in which A is a metal element such as Ge; B is a rare earth element except lanthanum or a metal element such as Ca or Sr; 0 ≤ x < 4, 0 ≤ y ≤ 0.3, 0 < z ≤1; n=0.7-1.4; α is a valence determined by the metal composition ratio) and contains a composite metal alkoxide formed from at least two metal alkoxides, i.e., oxides of Bi and Ti. The coating liquid is preferably a sol-gel liquid obtained by hydrolysis or partial condensation reaction treatment using water or water and a catalyst. Preferably, the coating liquid contains an alkanolamine.

Description

200536785 (1) IX. Description of the invention [Technical field to which the invention belongs] • The present invention relates to a coating solution for forming a bismuth-based dielectric thin film with a normal or ferroelectric property, and using the formed bismuth It is the invention of the dielectric film. The coating liquid of the present invention can make the normal dielectric forming material or the ferroelectric forming material fully exhibit its functions, and is widely applicable to those who use pyroelectricity, high dielectricity, or ferroelectricity. In particular, it is suitable for the characteristics required by semiconductor devices such as capacitors (film capacitors) or DRAMs and capacitors with non-volatile memory. [Previous technology] In recent years, as the memory capacity of semiconductor memory has been increased, DRAM (= Dynamic Random Access Memory), as a storage capacitor, has been researched using a high dielectric constant (high dielectric) Dielectric), constant dielectric or ferroelectric dielectric thin films. In addition, in non-volatile accumulation memory, research has been extensively conducted on the use of a dielectric film having a high dielectric property with high residual polarization characteristics, or using the history (hysteresis), or Develop a dielectric thin film material suitable for the memory element, and a method for forming the thin film. In the aforementioned semiconductor memory device, suitable materials can be used for the dielectric films of the normal to ferroelectric properties, depending on the application. Memory devices such as DRA Μ or SRAM (= Static R and 〇m Acess Mem 〇ry) are semiconductors, especially in the field of advanced microfabrication, and they are trusted to greatly suppress soft errors. -5- 200536785 (2) Generally, it is necessary to ensure that the capacitor capacity in the memory-cell is maintained above a certain level. In the past, a three-dimensional structure method has been used to ensure the capacitor area, and the electrical container is a SixNy film or a SiOx / SixNy laminated film to solve the aforementioned problems. Among them, SixNy film has high insulation and can be made into a thin film, and its specific permittivity (£) is as low as about 4 to 7. Therefore, it is necessary to have a three-dimensional structure in order to fully charge. # But the three-dimensional structure will cause a great burden on the planarization of the interlayer insulation film. In addition, from the viewpoint of reducing the leakage current, the thin film of the capacitor has also approached the critical point. Therefore, in the generations of 256M-DRAM and 1G-DRAM, breakthroughs in innovative technologies have been sought. In addition, many semiconductor devices other than memory, such as logic devices, have capacitors. The aforementioned devices are also the same, and technical breakthroughs are still being sought. In the foregoing situation, high-dielectric-permeability films, which are used as a material for capacitor structures, have gradually received increasing attention. High-dielectric films, such as Ta2 05 (oxidized giant: ε = 20 to # 3 5), or known perovskite-type unit crystal lattice structure, which exhibits constant dielectricity &lt; Electrical composite oxide ceramics. This composite oxide-based ceramic is known, for example, as BST (barium titanate 缌: ε = 400 or more) or PTZ (lead chromate titanate: ε = 1000 or more). When the high-dielectric film is used as a structural material of a capacitor, a sufficient capacity can be obtained even in a planar capacitor structure, so that the device is easier to manufacture and the reliability of the device can be improved. 200536785 (3) Especially in the production of laminated ceramic capacitors, at present, [3, butyric acid (it acid oxide) powder is slurried, and then formed into a film and then baked and produced: it is a general method ' However, it is not easy to reduce the thickness of the film. For fabrication, hundreds of layers are still required when the capacitor capacity is necessary. However, when using a high-dielectric film, it is possible to obtain a fairly high level without using the aforementioned multilayer capacity. The relationship between the electrostatic capacity (C) and the dielectric constant (ε) can be expressed by the following formula. • c = ε · S / D. (Where ε = ηΕ) (where C is the capacitance, ε is the permittivity, s is the electrode area, D is the film thickness, and n is the permittivity under vacuum ( 8.8541878 1 6 Ε'1 2), Ε is the specific permittivity) According to the above formula, in addition to reducing D (film thickness), S (electrode area) increasing, and increasing C (capacitance) In addition, there are methods to increase ε (dielectric rate) to increase c (capacitance). In order to avoid the problems caused by the three-dimensional structure mentioned above, the method of increasing ε is generally adopted, and Φ is the effective one by using a high dielectric material. Among the above-mentioned high-dielectric materials, lead-based dielectrics such as PTZ (lead titanate lead acid) are 'highly suitable for use as ferroelectric materials' due to their high residual polarization, etc. Ascension, has gradually sought an alternative material without giving. Ferroelectric materials other than lead-based ferroelectrics are known, for example, bismuth macromonate (SBT) (please refer to, for example, JP08-40965 A, JP 0 8-91 841 A), a part of the bismuth of BIT La substituted bismuth lanthanum titanate (BLT) (please refer to, for example, 卩 2003-192431 ，,]? 2003-82470A, JP2002-265 224A, JP2002-25557A) and other bismuth (Bi) 200536785 (4) system Reports on ferroelectric materials. BIT is a material with a higher residual polarized plutonium than SBT. It has been reported that BLT has a higher residual polarized plutonium than BIT, so it has attracted much attention in recent years. f The method for forming the aforementioned bismuth-based ferroelectric thin film includes, for example, a sputtering method, a C YD method, and a coating film formation method. However, the bismuth-based ferroelectric thin film is an oxide of a metal element constituting the thin film. There are many, so the thin film formation method of the sputtering method or the CVD method requires more expensive equipment because it requires expensive equipment. It is not suitable for controlling the composition of the dielectric film and is not easy to manage. Not easy to use for large-diameter substrates. In contrast, the coating-type film formation method does not require the use of expensive equipment, and the cost of film formation is relatively low, and it is easy to control the composition and content of the required dielectric film, and it is extremely promising. Technology. As the coating solution for forming a bismuth-based ferroelectric thin film used in this coating film formation method, for example, a carboxylic acid having a medium chain hydrocarbon group such as 2-ethylhexanoic acid and a constituent metal element of the thin film and Organic coatings, such as salts, or organometallic compounds such as alcohols such as ethanol, methoxyethanol, and #methoxypropanol, and metal alkoxides formed from the constituent metal elements of the film, dissolved in organic solvents液 等。 Liquid and so on. &quot; However, in order to stabilize the metal composition ratio in the coating solution, it is necessary to find a kind of material that can prevent the metal composition ratio in the film from being lost due to the loss of the metal (Si, etc.) with higher sublimability when the film is formed. The phenomenon of change. Therefore, among coating materials, it is highly anticipated that a material having a stable metal composition content and capable of suppressing a change in the metal composition ratio in the thin film to form a BIT-based or BLT-based ferroelectric thin film can be expected. • 8- 200536785 (5) In the field of semiconductor memory, there is also a need for constant dielectric properties. Therefore, there is also a great need to develop a device with constant dielectric properties, but with low leakage current and high dielectric constant. Of materials. Lin You, JP10-258 2 52A and JP10-259007A also disclose the attempt to compound alkoxy metal to stabilize the metal composition ratio to suppress the phenomenon of the change in the metal composition ratio in the film, etc., but the specific The materials described are only for SBT-based ferroelectric thin-film coating liquids, and for BIT-based and BLT-based ferroelectric thin-film coating liquids or ordinary dielectric film-forming coatings. The contents of the liquid are completely unrecorded. [Summary of the Invention] An object of the present invention is to provide a coating solution for a ferroelectric bismuth-based dielectric thin film having a stable metal composition ratio and capable of suppressing a change in the metal composition ratio in the film. According to another purpose of the present invention, according to its application, in order to provide a technical field with a high dielectric constant, a low leakage current, and a high dielectric compared to a ferroelectric and a constant dielectric. A coating solution for forming a ferroelectric bismuth-based dielectric thin film. In order to achieve the above-mentioned object of the present invention, the present invention provides a coating liquid, which is a coating liquid for forming a ferroelectric bismuth-based dielectric thin film containing a composite metal oxide represented by the following formula (1). Is a complex alkoxy metal formed from at least two alkoxy metals of Bi and Ti, {Bl4-x &gt; (L ^ z 'Β] -ζ) χ} η (Τΐ3-ν' Ay) 〇i2 -ra (I) -9- 200536785 (6) (where A is V, Cr, Mn, Si, Ge, Zr, Nb, Ru,

At least i metal elements selected from Sn, Ta, and W, and b is at least one metal element selected from the group consisting of rare earth elements containing lanthanum, Ca, Sr, and Ba 'X, y and z are each the number shown as 0Sx &lt; 4, 0 $ yS0.3, 0 &lt; ζ $ 1, η is a number from 0, 7 to 1.4, and α is a price determined according to the metal composition ratio). Also, the present invention is a coating liquid, which is a coating liquid for forming a bismuth-based xin dielectric film with a normal dielectricity, and is characterized in that it contains a composite of at least two alkoxy metals of Bi and Ti. The metal alkoxide, or a mixed metal alkoxide obtained by mixing at least alkoxylated Bi or alkoxylated Ti. The coating liquid may be a conventional dielectric material containing a composite metal oxide represented by the above formula (I) (wherein the definitions of A, B, X, y, z, n, and α are as shown above). A coating solution of a bismuth-based dielectric thin film is preferred. In addition, the present invention provides a method for forming a dielectric constant bismuth-based dielectric thin film. The method is to apply the above-mentioned coating solution for forming a dielectric constant bismuth-based dielectric thin film to a substrate. Under heat-drying treatment: heat treatment at 500 to 700 ° C (the first heat treatment) to form a coating film, and can be repeated as many times as necessary to the aforementioned coating to heat treatment (the first) (Heating and processing) to form a laminated layer of the coating film, and then, a heat treatment at 600 to 700 ° C (second heat treatment). In addition, the present invention further provides a normally-dielectric bismuth-based dielectric thin film, which is formed by coating a coating liquid for forming the above-mentioned normally-bismuth-based dielectric thin film on an electrode, and firing the Got. -10- 200536785 (7) [I ·] A coating solution for forming a bismuth-based dielectric thin film having a dielectric property (hereinafter, referred to as a "coating solution for forming a bismuth-based ferroelectric body"). The coating liquid for forming a secret ferroelectric thin film of the present invention is a coating liquid for forming a secret ferroelectric thin film containing a gold oxide not compounded by the following formula (I): {Bi4-x, (Laz, BbZ) x} n (Ti3_y, Ay) 〇12 + α (I) In the above formula, A is V, C r, M η, Si, Ge, Z r, N b, ® Ru, Sn , Ta, and w, at least one metal element selected. The coating solution for forming a ferroelectric thin film is preferably A in which A is Ge. B is at least one metal element selected from rare earth elements not containing lanthanum, Ca, Sr, and Ba. Among them, the lanthanide is more preferable, and the use of spectrum (P r) and europium (C e) 'sharp (N d) is the best. X is a number shown by 0Sx <4, preferably 0 &lt; x &lt; 4, and y is a number of 0 € yS0.3, and more preferably 0 &lt; yg0.3. When Ge is used for the A metal, y is preferably y = 0.05 to 0.20, and particularly preferably y = ⑩ 0.10 to 0.15. Z is a number shown by 0 &lt; zgl, and 0 &lt; Z &lt; 1 is preferred. η is a number from 0.7 to 1.4. α is a valence determined by the metal composition ratio. 5 S a S 5 'is more preferably _2SaS2. In addition, the coating liquid is a gel-sol obtained by using a composite alkoxide metal composed of at least two kinds of alkoxy metals such as Bi and Ti, and hydrolyzing and partially condensing water or a catalyst. liquid. That is, in the manufacturing method of the coating liquid of the present invention, among the metal elements of 200536785 (8) contained in the coating liquid, Bi and Ti are both metal alkoxides as a starting material. La, A metal element, b metal element (there is also a case that does not include A. metal element, B metal element), it is better to use the metal alkoxide as the starting material, and metal acetate can also be used (E.g., lanthanum acetate, etc.), Θ-diketone metal complexes, and the like may be used as starting materials. Its content is not limited by the examples. In the present invention, lanthanum is preferably used as a metal acetate® salt (lanthanum acetate) from the viewpoints of easy availability, economy, and excellent characteristics. A metal element and B metal element are preferably alkoxymetals. Specific examples are as follows (in the case where A metal element and B metal are included), but the present invention is not limited by the following examples. (a) Contains BiTi complex metal alkoxide, lanthanum oxide (or acetate, etc.), metal A alkoxide (or acetate, etc.), metal B alkoxide (or acetate, etc.). (b) Contains BiTi La complex metal alkoxides, metal A alkoxides (or acetic acid salts, etc.), and metal oxides (or acetates, etc.). (c) Contains BiTiLaA metal composite alkoxide, metal B alkoxide (or acetate, etc.). &quot; (d) State containing BiTiLaA metal B metal complex alkoxide and the like. In the present invention, the metal element is preferably the above-mentioned (d) state of the complex alkoxide. As mentioned above, the use of two or more dissimilar metals as a composite alkoxy metallization result can effectively suppress the precipitation (segregation) and burnout of individual metal elements. -12- 200536785 (9) The compound alkoxy metal referred to in the present invention is, for example, bismuth alkoxide, titanium alkoxide, and other metal elements (La, A metal element, B metal element) alkoxide, acetate, / 3 -Diketone metal complex and other things, in a solvent, under heating conditions at 30 to 100 ° C, for 2 to 15 hours of the compound obtained under reflux. The end point of the reaction is that the liquid slowly changes color until the final dark brown liquid is reached. The point at which the liquid completely changes color is the end point of the reaction. The composite alkoxy metal obtained according to the aforementioned method is applicable to, for example, ρρ · 46 to 47 of the "Manufacturing Technology and Application of Glass-Ceramics by Gel-Gel-Sol Method" (Application Technology Publishing Company, June 4, 1989). As defined. Specifically, for example, TiBi (OR) 4 (OR) 3, LaTiBi (OR) 3 (〇R) 4 (〇R) 3, LaTiBiA (OR) 3 (〇R) 4 (OR) 3 (OR) m, LaTiBiB (OR) 3 (OR) 4 (OR) 3 (OR) n 'LaTiBiAB (OR) 3 (OR) 4 (OR) 3 (〇R) m (OR) n (wherein A and B are defined as above Shown; m is the atomic valence of the A metal element; n is the atomic valence of the B metal element; R is an independent alkyl group having 1 to 6 carbon atoms), but the present invention is not limited thereto. In the present invention, since Bi with high sublimability is used as an essential metal element to be compounded with T i, it is possible to form a film at a ratio close to the feed material. It is preferable to use the alcohol represented by the following formula (II) to form an alcohol of a metal alkoxide or a composite alkoxide. R] 〇H (II) (where R! Is a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms) Specific examples of the aforementioned alcohols, such as methanol, ethanol, propanol, butanol, pentane -200536785 (10) Alcohol, cyclohexanol, etc. Alcohols other than the above alcohols, such as those in which R1 is further substituted with an alkoxy group having 1 to 6 carbon atoms, specifically, for example, methoxymethanol, methoxyethanol,

I ethoxymethanol, ethoxyethanol, etc. 1 Some of the alkoxy groups such as the aforementioned metal alkoxides and composite metal alkoxides may be substituted by alkaneamines, carboxylic anhydrides, dicarboxylic acid monoesters, / 3-diones, and diols. Yes. # The coating liquid of the present invention is preferably a gel / sol solution obtained by using the coating liquid containing the above-mentioned composite alkoxy metal, followed by hydrolysis or partial condensation treatment with water or water and a catalyst. For the hydrolysis reaction, for example, adding water or water and a catalyst to the coating solution, and stirring at 20 to 50 ° C for several hours to several days. The catalyst is known, for example, as a well-known substance used in the hydrolysis reaction of metal alkoxides, such as inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, organic acids such as acetic acid, propionic acid, butyric acid, or sodium hydroxide, Inorganic-organic base catalysts such as potassium, ammonia, monoethanolamine, diethanolamine, and tetramethylammonium hydroxide®. Among them, inorganic alkalis such as sodium hydroxide and potassium hydroxide, if metal ions such as sodium and potassium remain in the coating liquid, there will be doubts about the electrical characteristics of the coating, and nitrogen-containing systems such as ammonia and amines will cause After the hydrolysis reaction, there will be a case where a nitride with a higher boiling point is formed. 'There will be doubts that the film will be densified during the firing step. Therefore, in the present invention, the use of an acid catalyst is the best. The hydrolysis reaction is performed by coating the coating solution on the electrode, and then exposing the surface of the film to a humidified environment, for example, 50 to 120. (: It is better to carry out under 10 to 60 minutes and humidity of 50 to 100%. -14- 200536785 (11) The above conditions can be used in conjunction with the use of the film to make appropriate choices, and are not limited to the above The foregoing hydrolysis treatment can reduce the content of organic components in the entire coating film after the drying step, and can form complex bonds of various metals, so it can control the precipitation and burnout of metals such as bismuth. The reason is that Various organometallic compounds' organic groups in their structures are often detached from organic groups such as alkoxy groups by hydrolysis treatment, and can be reattached to more inorganic metal complex bonds #, etc. The detached organic groups, Low-boiling alcohols, diols, etc. are formed and remain in the coating solution or film, and evaporate with the solvent at the same time in the drying step, which can increase the inorganicity of the film before the firing step and form a dense film It also increases the bonding strength of metal elements through the formation of composites and metal complex bonds, and suppresses the precipitation (segregation) and burnout of metal elements such as bismuth to reduce leakage current and form Films with excellent hydrogen heat resistance and pressure resistance. In addition, the coating liquid of the present invention is preferably one added with an alkanolamine. By using an alkanolamine, it has an effect of improving the coating property in particular. Alcohol amines, such as triethanolamine, diethanolamine, dibutylethanolamine, diethylethionamine, etc. Among them, from the viewpoint of improving coating properties, it is best to use triethanolamine. The amount to be added is, for example, 1 mol of the composite metal oxide shown in the above formula (I) (wherein A, B, X, y, ζ, η, and α have the same definitions as above), which is 0. 5 to 2 0 mol, especially in the range of 1 to 10 mol. When it exceeds the above range, even if an alkanolamine is added, there is a tendency that a sufficient effect cannot be obtained, which is not good. -15- (12) (12) 200536785 The addition of alkanolamine is preferably performed after the hydrolysis treatment in the above-mentioned hydrolysis treatment process. In the present invention, a stabilizer known in the past may be further added. The stabilizer is used to improve the storage stability of the coating solution. For example, carboxylic anhydrides, dicarboxylic monoesters, and Θ-diketones are used, Diols and the like are preferred. Carboxylic anhydrides are, for example, the following formula (III) R2 (CO) 20 (III) (wherein R2 is a divalent saturated or unsaturated carbon number of 1 to 6) At least one selected from the carboxylic anhydrides shown in the above is preferred. The aforementioned acid anhydrides: specifically, for example, maleic anhydride, citraconic anhydride, itaconic anhydride, succinic anhydride, methylsuccinic acid, pentyl Diacid anhydride, α-methylglutaric anhydride, α, α-dimethylglutaric anhydride, trimethylglutaric anhydride, etc. Dicarboxylic acid monoesters are, for example, represented by the following formula (IV) R3OCOR4COOH (IV) ( In the formula, R3 is a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms; r4 is a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms having a divalent carbon number. Preferably, at least i species are selected. The aforementioned dicarboxylic acid monoesters, for example, can be specifically formed by reacting a carboxylic acid of a dibasic acid with an alcohol to form a half-esterified product. Pimelic acid, suberic acid, azelaic acid, sebacic acid, maleic acid, citraconic acid, itaconic acid, methylsuccinic acid, α-methylglutaric anhydride, α, α-dimethylglutaric acid From acid anhydride and trimethylglutaric anhydride to -16-200536785 (13) Less than one kind, and methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, pentyl alcohol, hexyl alcohol, ethylene glycol mono At least one of methyl ether, propylene glycol monomethyl ether, and the like is synthesized by esterification according to a known method. / 3-diketones include, for example, the following formula (V) R5COCR6HCOR7 (V) (where R 5 is a saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms; R 6 is fluorene or CH 3; R 7 is a carbon number The alkyl or alkoxy group of 1 to 6) is preferably at least one selected from the group consisting of stone and dione of / 3-dione esters. Theta-diketones used in the present invention are, for example, acetoacetone, 3-methyl-2,4-pentanedione, phenylacetone and the like. Examples of the stone-ketoester include ethyl acetone and diethyl malonate. It can also use other complex-forming agents' but dimethyl trimethyl ethyl methane or its THF adduct, or hexafluoroacetamidine acetone such as metal halide after firing, because Metal complexes with high sublimation or volatility are formed, so they are not suitable for the coating liquid of the present invention. Diols are, for example, at least one selected from the following diols (VI) hor8oh (VI) (wherein, 'R8 is a divalent saturated or unsaturated hydrocarbon group having 1 to 6 carbon atoms) Better. Specific examples of the diols used in the present invention include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, pentanediol, hexanediol, 2-ethylethoxydiol, and glycerol Diols, etc. The aforementioned diols are particularly effective when used as a diazepam / 3-17-200536785 (14) chelating agent, which can improve the stability of the liquid after the hydrolysis reaction. The stabilizing agents above r are all those having a short chain of 1 to 6 carbon atoms, and are preferred from the viewpoint of improving the inorganic nature of the film after the drying step. Furthermore, substituted or unsubstituted lower monocarboxylic acids such as acetic acid, propionic acid, diethylhexane, butyric acid, and valeric acid are also suitable as stabilizers. The composite metal alkoxides are acidified, petro-diketoned, and clamped by using carboxylic acid esters, dicarboxylic acid monoesters, i-diketones, glycols, lower monocarboxylic acids, and the like. Such processing results can produce polar products with excellent stability in the province, which can improve the hydrolyzability, and can improve the practical solubility of polar solvents. As a result, the polycondensation reaction by the gel-sol method in the coating liquid can be made more sufficient. By forming an inorganic bond (metal complex) obtained from a metal-oxygen atom, the specific metal element such as bismuth can be reduced. Simultaneously with the amount of precipitation (segregation) and the amount of burnout, the inorganicization of the entire coating liquid is improved. The "stabilizing treatment" and the "hydrolytic treatment" of the above-mentioned stabilization agent may be performed by blasting, regardless of whether any treatment is performed first or two treatments are performed simultaneously. gfl describes the hydrolysis treatment and stabilization treatment, which can improve the storage stability of the coating liquid: qualitative, operational, low-temperature decomposition, high density, coating properties, etc., and can improve the solubility of practical organic solvents. Solvent for the above bismuth-based ferroelectric thin film coating liquid, for example, saturated aliphatic solvents, aromatic solvents, alcohol solvents, glycol solvents, ether solvents, ketone solvents, ester solvents Wait. Examples of the alcohol-based solvent include methanol, ethanol, propanol, butanol, pentanol, cyclohex-18-200536785 (15) alcohol, methylcyclohexanol, and the like. Diol solvents such as ethylene glycol monomethyl ether, ethylene glycol monoacetate, diethylene glycol monomethyl ether, diethylene glycol monoacetate, propylene glycol monomethyl ether, and propylene glycol monoethyl ether Ether, propylene glycol monoacetate, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol dipropyl ether, dipropylene glycol monoethyl ether, 3-methoxyl-butanol, 3-methoxy- 3-methylbutanol, 3,3, -dimethylbutanol and the like. # Ether solvents such as methylal, diethyl ether, dipropyl ether, dibutyl ether, dipentyl ether, diethyl acetal 'dihexyl ether, trioxane, and dioxanone solvents such as Acetone, methyl ethyl ketone, methyl propyl ketone, methyl isobutyl ketone, methyl amyl ketone, methyl cyclohexyl ketone, diethyl ketone, ethyl butyl ketone, trimethyl nonyl ketone , Acetonitrile, acetone, dimethyl oxide, phorone, cyclohexane, diacetone alcohol, etc. Ester-based solvents, such as ethyl formate, methyl acetate, ethyl acetate, ethyl butyl acetate, cyclohexyl acetate, methyl propionate, ethyl acetate, ethyl oxoisobutyrate, ethyl acetate , Ethyl lactate, methoxybutyl acetate, diethyl oxalate, diethyl malonate, triethyl citrate, tributyl citrate, and the like. In addition, in the gelation and stabilization of hydrolysis, the present invention is not limited to the low-boiling alcohol solvents used in the past. It can also be used in combination with aromatic compounds (such as toluene or xylene) or high-boiling glycols. . These solvents may be used singly or as a mixture of two or more. For reasons such as coatability when forming a thin film of the present invention or stability of a coating liquid '-19- 200536785 (16) A solvent other than an alcohol-based solvent may be used. Particularly, an ethylene glycol-based solvent is preferably used.

In the above coating solution for forming a bismuth-based ferroelectric thin film, Bi, Ti, and Ar metal elements (when A element is not included, calculated as A = 0) are represented by Bi: (Ti + A) 1.07 to 1.15: 1 (Mole ratio) is preferred. When the molar ratio of each component in the coating liquid is adjusted within the above range, a coating film having excellent strong dielectric properties and a high polar content (Pr) can be formed. • Next, a method for manufacturing a ferroelectric thin film and a ferroelectric memory (ferroelectric element) using the coating solution for forming a bismuth-based ferroelectric thin film of the present invention will be described. However, the present invention is not limited to this. First, 'oxidize a substrate such as a silicon wafer to form a silicon oxide film on the substrate', and then form a metal such as Pt, Ir, RU, Re, 0s, and its metal oxide by sputtering, evaporation, or the like. Conductive metal oxide to make the lower electrode. Subsequently, the coating solution of the present invention is coated on the lower electrode by a known coating method such as a spin coating method, a dip coating method, and the like, and then at 50 to 400 ° C, preferably 150 to 30 °. The first heat treatment (drying) was performed at a temperature of 0r to form a coating film. Secondly, in accordance with the required target, repeat the processing steps from coating to drying several times to achieve the desired film thickness and degree.

Im Secondly, the main firing is performed in an oxygen environment at a temperature of 600 to 7500 aC to form a strong dielectric film having a crystalline structure. In the main firing step, for example, the temperature of the main firing of the dish soil can be raised from room temperature at a heating rate of about 5 to 20 ° C / min, and then maintained at the main firing temperature for about 10 to 80 minutes. Furnace firing method, the temperature is raised from room temperature to the official firing temperature at a temperature increase rate of about 50 to 5 IO / sec, and then maintained at the official firing temperature of 20 · 200536785 (17) at a firing temperature of 0.5 It can be selected from various roasting methods, such as the RPT method, which is roasted to about 3 minutes. When coated with the present invention for one time, the main firing (crystallization of the film composition) can be performed at a low temperature of 600 to 700 ° C. Secondly, an electrode (upper electrode) is formed on the ferroelectric thin film produced as described above. For the upper electrode, for example, the metals and metal oxides listed for the material for the lower electrode can be used. The aforementioned materials can be formed by sputtering, evaporation, etc .: • It is formed on a ferroelectric thin film by a known method, and it is exposed to oxygen. ., Bake at 600 to 700 ° C to make ferroelectric memory. At this time, the upper electrode 'may be made of a material different from that of the lower electrode. For example, Ir may be used for the lower electrode, and Ru may be used for the upper electrode. When the hydrolysis reaction is performed in a humidified environment, the temperature is 50 to 100%, preferably 70 to 100%, and the temperature is 50 to 120C. Up to 60 minutes is preferred. In the present invention, in the production of the coating liquid, especially when it is compounded and inorganicized through hydrolysis, the bond between metals can be enhanced to suppress the precipitation (segregation) of metal elements, burnout, etc., and the leakage current can be suppressed, and Can improve the properties of strong dielectric memory such as crystallinity, hydrogen heat resistance and pressure resistance. After the formation of the upper electrode, a protective film (passivation) such as Si02, aluminum wiring, etc. are formed. Especially, it has excellent hydrogen heat resistance. Therefore, it can reduce the formation of strong dielectric when forming a passivation film and aluminum wiring. Concerns about the deterioration of electrical properties have led to the practical use of BLSF films to make ferroelectric memory. In addition, the inorganicization obtained by the above-mentioned gel-sol method (hydrolysis method) is incomplete-21-200536785 (18) The entire coating solution, and the coating solution that is not completely hydrolyzed, is used to form a coating on the substrate through After the film is exposed to a humidified environment for a certain period of time before firing, the film can be inorganicized by hydrolytic polycondensation, and then shaped.

I into a dense film. % The hydrolysis treatment in the aforementioned coating solution will cause thickening-gelation of the coating solution when it is excessively carried out, or there may be doubts such as storage changes, so the hydrolysis treatment when the soil coating is formed is also effective Method. # [π.] A coating solution for forming a bismuth-based dielectric thin film having a constant dielectric property (hereinafter referred to as a "coating solution for forming a bismuth-based constant dielectric film") The bismuth-based constant dielectric film of the present invention is formed The coating solution is a compound containing alkoxy metal composed of at least two kinds of alkoxy metals of B i and Ti, or a bismuth formed from a mixed alkoxy metal obtained by mixing at least bismuth alkoxide and titanium alkoxide. It is a coating solution for a normal dielectric film. A mixed oxide is prepared by adding bismuth alkoxide and titanium alkoxide to an alcohol solution, for example. Alcohols that can be used as metal alkoxides include, for example, the alcohols listed in [I.] above. The composite metal alkoxide can be produced, for example, by the method described in the item [I ·] above. The coating liquid for forming a bismuth-based constant dielectric film of the present invention prepared in this manner also includes a BIT-based coating liquid. When mixed alkoxide is contained, it has the effect of reducing the shallow current. When a composite metal alkoxide is used, the film can obtain excellent denseness. The above-mentioned coating solution for forming a bismuth-based constant dielectric film is preferably, for example, to form a normal dielectric bismuth-based dielectric film (ie, a BLT film) containing the composite metal oxide described in the item [I.] above. Those are better. In the formula, A, B, -22- (19) 200536785 x, y, z, n, 0: The definitions are as described above. Among them, the normal dielectric film also contains the form of a mixed oxide obtained by mixing bismuth alkoxide and titanium epoxide. It may be a complex metal alkoxide containing bismuth and titanium. The difference between the formation content of the normal dielectric film and the formation valley of the ferroelectric thin film ', for example, when the compound represented by the above formula (I) is contained, it is mainly a difference in composition and a film formation condition. When the method for forming the thin film represented by formula (I) is illustrated, for example, a coating liquid for forming a ferroelectric thin film is used, as described in the above item [I.], the proportion of the metal element in the coating liquid, B The i, Ti and A metal elements are preferably adjusted to a ratio of Bi: (Ti + A) = 1.07 to 1.15: 1 (molar ratio). Further, Ge is preferably used as the A metal element. On the other hand, in the coating solution for forming a constant dielectric film, the ratios of Bi, Ti, and A metal elements to Bi: (Ti + A) = 0.90 to 1.06: 1 (Molar ratio) are preferably adjusted. In the coating solution for forming a dielectric thin film, when the metal element A is Ge or B, it is preferable to use Sr, Ba, Pr, Er, Y, or the like. The formation conditions of the coating liquid for forming a dielectric thin film are as follows. When the coating liquid is adjusted to a composition of Bi: (Ti + A) = 0.90 to 1.06: 1 (molar ratio), the coating liquid can be formed by a conventional method for forming a dielectric film without requiring a special formation method. Normally dielectric film. In addition, a more suitable forming method is, for example, applying a coating liquid on a substrate, and then performing a first heat treatment (drying) at a temperature of 50 to 400 ° C, preferably 150 to 300 ° C to form a coating. membrane. Secondly, according to the required target, repeat the processing steps from coating to drying several times to form a layer-23- (20) (20) 200536785 composite film, and secondly, at 600 to 700 ° C, preferably 600 A method of forming a thin film by performing a second heat treatment (baking treatment) at 670 ° C. According to this method, a conventional dielectric film having a constant dielectric property and a high dielectric constant can be obtained. When the coating solution is not adjusted to a combination of Bi: (Ti + A) = 0.90 to 1.06: 1 (molar ratio), it is preferable to use the following method when forming a more appropriate normal dielectric film. For example, the coating liquid is coated on a substrate, and the first time is performed at a temperature of 500 to 700 ° C, preferably 5500 to 6500 ° C without drying treatment by heating. Heat treatment (pre-firing) to form a coating film. Secondly, according to the required target, the processing steps from coating to drying are repeated several times to form a laminate of the coating film, and secondly, from 600 to 700. (:, A method of forming a thin film by performing a second heat treatment (baking process) at a temperature of preferably 600 to 670 ° C. According to this method, it is possible to form an electrode with constant dielectric constant and high dielectric constant. Dielectric thin film. Also, the above-mentioned drying treatment means that the coating film is dried without being subjected to substantial heating treatment, and is buried in a heating place where the organic components in the coating film are not decomposed (for example, near normal temperature) Temperature) is also included in the aforementioned treatment. Components (such as solvents, stabilizers, alkanolamines, etc.) that can be added to the coating liquid for forming a dielectric film, conditions for forming a dielectric element, etc. ' The contents are as described in the above item [I ·]. In addition, the content of Bi, Ti, La, A metal element components, and B metal element contents in the coating solution for forming a bismuth-based ferroelectric thin film is in accordance with this specification. Invention • 24-200536785 (21) There are various changes in the use place and conditions of the coating solution, such as the type (FRAM, DRAM, MFS, tmfmis, etc.) or the upper and lower electrodes used Degree, composition, type of barrier layer, thickness, You can choose an appropriate number according to the situation. Organic = metal compound addition amount, residual alkane and amount, carbonyl group addition ratio, complex degree, hydrolysis rate, etc. • Degree, complex alkane oxidation Degree, etc., can be matched with the selection of the coating liquid of the present invention (temperature, time, environment, and temperature during drying and baking). It is exemplified, but it is limited by the following examples. [Embodiment] Example ® The present invention will be described in more detail with examples below and is not limited by the following examples. 1 [Formation of bismuth-based ferroelectric thin film Coating solution] Synthesis example 1 [In the above formula (I), a coating solution (Bi: (Ti + A) (Molar ratio)) represented by n = 1.0250, x = 0.7317, 1, and α = 0.1500] Add 0.0750 Mo to bupropoxy-2-propanol: for example, suitable for MFIS, the type of thick film with or without oxygen, or the use of polycondensation, condition method, etc.) as appropriate, relative The invention is not affected, but the invention y = 0, z = = 1.12: 1: Lanthanum acetate , -25- 200536785 (22) 0.300 Molar tetrabutoxytitanium, put it into an eggplant-shaped flask, and heat and stir at 80 ° C. Add 0.35 Mo Bismuth tributoxy bismuth is heated and stirred at 60 ° C to synthesize 3 kinds of composite alkoxymetals (BLT-based composite liquid) of Bi-Ti-La. To the above-mentioned BLT-based composite liquid, 0.3000 is added. Mole's stabilizer 2.Ethylhexanoic acid was stirred at room temperature. After adding 2,000 moles of stabilizer Triethanolamine, it was heated and concentrated at 60 ° C to obtain b methoxyl. The lanthanum bismuth titanate (BLT-based) film substituted with 1,2-dimethoxy-propane to form a spin coating solution. Synthesis Example 2 [In the above formula (I), n = 1.0250, X = 0.7317 ^ y = 0, z = 1, α = 0.1500 (Bi: (Ti + A) = 1.12: 1 (Mole ratio))] To 1-methoxy-2-propanol, add 0.07 50 moles of lanthanum acetate and 0.3 000 moles of tetrabutoxytitanium, and place them in an eggplant-shaped flask. Medium, heat and stir at 80 ° C. To this was added 0.33 350 mol of tributoxybismuth, followed by heating and stirring at 6 ° C to synthesize 3 kinds of composite alkoxymetals (BLT-based composite liquid) of Bi-Ti-La.

To the above-mentioned BLT-based complexing solution, 0.3000 mol of stabilizer, acetic acid, was added, followed by heating and stirring, and then 0.2000 mol of water was added, followed by stirring at room temperature. Then, propylene glycol, which is an additive of 0,000,000 mole stabilizer, was added thereto, followed by stirring at room temperature to obtain a coating solution for forming a lanthanum bismuth titanate (B LT series) thin film. -26- 200536785 (23) Synthesis Example 3 [In the above formula (I), 11 = 1.0250, X = 0.6 8 2 9 'y = 〇Qin 0.5, α = 0.1500 coating solution (Bi: (Ti + A) two ;! "^ (Mole ratio))] After adding 0.0400 mol acetic acid 0.3 000 mol tetrabutoxytitanium to bupropoxy-2-propanol, put it into the eggplant flask , J • Heat and stir at ° C. Add 0. 3 4 0 0 Mole tributoxy 0.03 00 Mole triisopropoxy hydrazone, and heat and stir at 60 ° C to form 4 kinds of complex alkoxy compounds Bi-Ti-La-Pr Metal (BLT system rehydration). To the BLT-based composite solution, 0.2000 moles of water was added and stirred at room temperature. To this was added 0.3 000 mol of stabilized 2-ethylhexanoic acid, followed by stirring at room temperature, and heating and concentration at 60 ° C to obtain 1-methoxy-2-propanol and 1,2- Dimethoxy-propane-substituted titanium #bismuth (BLT-based) film-forming coating solution. Synthesis Example 4 '[In the above formula (I), η = 0.9762, x = 0.6829, 0 · 1 429, z = 1, α = -〇 · ΐ 429, the coating solution (] (Ti + A ) = 1 · 08 ·· 1 (mole ratio))] To bupropoxy-2-propanol, add 0.0667 mol acetic acid, 0.2857 mol tetrabutoxytitanium, · (Η43 mol tetrabutoxy) After the basic germanium is put into an eggplant-shaped flask and heated and stirred at 80 ° C. In it, 3: 1 lanthanum, ^ 8 0 bismuth, combined with each other, and then added with lanthanum acid y = lanthanum, and then Add -27- 200536785 (24) 0.3238 mols of bismuth tributoxy, and heat and stir at 60 ° C to form 4 kinds of complex alkoxymetals (BLT-based complex liquid) of Bi-Ti-La-Ge.

I Add 0.2 000 mol of water to the BLT-based composite solution, and stir at room temperature. Add 0.3 000 mol of stabilizer hexanoic acid, stir at room temperature, heat and concentrate at 60 ° C to make methoxy-2-propanol and 1,2-dimethoxy -Propane-substituted acetic acid • (BLT-based) film-forming coating solution. Synthesis Example 5 [In the above formula (ί), η = 0.9881, x = q.7Q8q, 0.1 4 2 9, and ζ = 0 · 9 4 3 5, and α =-0.0 7 1 4 (( Ti + A) = 1.08: 1 (mole ratio))] Added to the methyl methoxy-2-propanol, 0.0660 mol acetic acid 0.004 mol trimethoxypropionate, 0.2857 mol four After butoxyluz. 〇1 4 3 Wu Tetrabutoxy, put it in a section flask, and heat and stir at ° c. 0. 3 2 3 8 mol of tributoxy was added thereto, followed by heating and stirring at 60 ° C. to synthesize a 5-metal alkoxy metal (BLT composite liquid) of Bi-Ti-La-Ce-Ge. 0,2000 moles of water was added to the BLT-based composite solution, and the mixture was stirred at a temperature. To this was added 0.3 000 mol of stabilizer 2 hexanoic acid, followed by stirring at room temperature, and heating and concentration at 60 t to obtain oxy-2-propanol and 1,2-dimethoxy-propane. Substituted lanthanum titanate-based) thin film forming coating solution. Combining in combination in room 2-B gives 1- steel secret

y = Bi: lanthanum, titanium, bismuth at 80, bismuth, compound-ethyl 1-methyl (BLT -28- 200536785 (25) [Coating solution for forming bismuth-based constant dielectric thin film] Synthesis Example 6 _ q 92: 1 1. Coating solution (Bi: (Ti + A)-· (mole ratio)) shown in α _ 1.020 in 1-methoxy-2-propanol, 0.3 000 After Moore tetrabutoxide titanium, heat and stir at ° C. Add 0. 0 5 60 Molar acetate fiber and place it in an eggplant-type flask. '800.2760 Molar tributoxybismuth 'Then heat and stir at 60 ° C to synthesize 3 kinds of composite alkoxymetals (BLT-based composite liquid) of Bi-Ti-La. Add 0 · 2 0 0 0 Mo to the BLT-based composite liquid Ear water, stirred at room temperature. After adding 0.3 000 mol of stabilizer 2-ethylhexanoic acid to it, stir at room temperature, heat it at 60 ° C and concentrate to obtain 1- Coating solution for forming lanthanum bismuth titanate (BLT-based) thin film in which methoxy-2-propanol is replaced by it dimethoxy-propane. Synthesis Example 7 [In the above formula (I), η = 0.93; 38. Coating liquid shown by x = 0.6747, y = 〇, z = 1, α = -0.3 975 (Bi: (Ti + A)-1. 04: 1 (Mole ratio))] After the addition of 0 · 〇 6 3 〇 Mor lanthanum acetate, 0 · j 0 0 0 四 Tetrabutoxy titanium It was placed in an eggplant-shaped flask, and heated and stirred at 80 ° C. To this was added 0.3 mol of bismuth tributoxy, 29-200536785 (26) and then heated and stirred at 60 ° C to Synthesized Bi-Ti_La 3 yausong compound metal alkoxide (BLT-based composite liquid). Add 0.2000 Moist to the above-mentioned BLT-based composite liquid, stir with water 'at room temperature. Add 0.3 00 to it 0 moles of stabilizer,, ,, and 2-ethylhexanoic acid, after stirring at room temperature, heating and concentrating it at 60 t to produce 1-methoxy-2-propanol from = 2¾ Coating solution for forming a thin film of arsenic acid (BLT system) substituted with 1,2 · dimethoxy-propane. Synthesis Example 8 [In the above formula (I), η = 1.0375 and χ = 1.3398 , V — λ y — ό-z = 0.4029, α = 0.2250 (Bi: (Ti + A) 0.92: 1 (Molar ratio))] in methoxy-2-propanol After adding 0.0 5 60 moles of acetate steel and 0.3 000 moles of tetrabutoxytitanium, place them Put it into an eggplant-type flask, and heat and stir at 80 ° C. Add 0.2760 mol of tributoxy sharp, Φ 0.0830 mol of triisopropoxy hydrazone, and heat and stir at 60 ° C to synthesize 4 kinds of composite alkoxymetals of Bi-Ti-La-Pr (BLT compound liquid). 0.2000 moles of water was added to the BLT-based composite solution, and the mixture was stirred at room temperature. To this was added 0.3000 mol of stabilizer 2-ethylhexanoic acid, and the mixture was stirred at room temperature, and it was concentrated by heating at 60 ° C to obtain dimethoxy-2-propanol. Coating solution for 2-dimethoxy-propane-substituted lanthanum bismuth titanate (BLT-based) thin film formation. -30- 200536785 (27) Synthesis Example 9 [In the above formula (I), the coating liquid represented by 'n == 0.8893, χ == 06747 0.1429, ζ 2 1, and a = -0.6645 (_ (Ti + A) · 99: 1 (Mole ratio))] After adding to the methoxymethyl-2-propanol, 0.0600 mole of acetol 0.2875 mole of tetrabutoxy titanium, 0.0143 mole of tetrabutoxy germanium Put into eggplant-shaped flask, and heat and stir at 80 ° C. In its inch 0,2957 moles of bismuth tributoxy, it was heated at 60 ° C to accompany four kinds of complex alkoxymetals (BLT series liquid) of Bi-Ti-La-Ge. To the above-mentioned BΊ5Γ-based composite solution was added 0.200 mol water temperature and stirred. To which 0.3000 mol of stabilizer is added: After hexanoic acid, stir at room temperature, heat it at 60 ° C and concentrate it to write], 2-Methoxy-propanyl lanthanum acetate BLT system) thin film forms humor. Synthesis Example 1 [In the above formula (I), a coating solution ((Ti + A) = 1) represented by n = 0.9881, χ = 0.8210, 1429, ζ = 0.07622, and j = -〇〇714. 5:] (Mole ratio))] ^ K methoxy-2 -propanol, 0.0633 moles acetic acid 0.2875 several ears tetrabutoxytitanium, 0.003 43 moles tetrabutoxy germanium Then, it was placed in an addition flask and heated and stirred at 80 t. In it, 褽 bismuth tributoxy, 0.0198 mol isopropoxy bait,, y = Bi: only lanthanum,, add it ^ to combine [combination, in the chamber!-Ethyl 5 generation as 3 Coating y = Bi: lanthanum, adding it and heating and stirring at -31- 200536785 (28) at 60 ° C to synthesize 5 kinds of compound oxygen metal (BLT series) of Bi-Ti-La-Er-Ge Compound fluid). t Add 0.2000 moles of water to the BLT-based composite solution, and stir at room temperature. To this was added 0.3000 mol of stabilizing agent of 2-ethylhexanoic acid, and the mixture was stirred at room temperature, and it was heated and concentrated at 60 ° C to obtain 1-methoxy-2-propanol. Coating solution for 2-dimethoxy-propane-substituted lanthanum bismuth titanate (BLT-based) thin film formation. Synthesis Example 11 [In the above formula (I), η = 0.9881, x = 0.8210, y = 0.1429, ζ = 0.7622, a = -0.0 7 16 ) = 1.05 · 1 (mole ratio))] To b methoxy-2-propanol, add 0.063 3 mol lanthanum acetate, 0.2875 mol tetrabutoxy titanium, 0.0143 mol tetrabutoxy After basic germanium was put into an eggplant-shaped flask, it was heated and stirred at 8CTC. Add # 0.3121 mole of bismuth tributoxy, 0.0198 mole of trimethoxypropionate, and heat and stir at 60 ° C to synthesize 5 complex alkoxy compounds of Bi-Ti-La-Y-Ge Metal (BLT compound liquid). • Added 0.22000 mole water 'to the BLT-based composite solution and stirred at room temperature. To this was added 0.3000 mol of stabilizer 2-ethylhexanoic acid, and the mixture was stirred at room temperature, and it was heated and concentrated at 60 ° C to obtain 1-methoxy-2-propanol. 2. Dimethoxy-propane-substituted lanthanum titanate (BLT-based) film-forming coating solution. -32- 200536785 (29) Synthesis Example 1 [In the above formula (I), η = 1 · 〇Bi28, x = 0.9l80, 乂 0.1429, z = 0.6812, α = 0.0768 (Bi : t. (Ti + A) = 1 · 04: 1 (mole ratio))] To bupropoxy-2-propanol, 0.063 mole lanthanum acetate, 0.2875 mole tetrabutoxy After titanium and 0.0143 mole tetrabutoxygermanium, put it into an eggplant-shaped flask, and heat and stir at 80 ° C. Add 0.3121 mol of bismuth tributoxy and 0.0296 mol of barium diisopropoxide, and heat and stir at 60 ° C to synthesize 5 kinds of compound courtyard oxygen of Bi-Ti-La-Ba-Ge Metal (BLT compound liquid). 0.2000 moles of water 'was added to the BLT-based composite solution, and the mixture was stirred at room temperature. Add 2 000 ethyl hexanoic acid, a stabilizer of 0.3 000 mol, and stir at room temperature, then heat and concentrate it at 60 ° C to obtain 1-methoxy-2-propanol. A coating solution for forming a 1,2 · dimethoxy · propane-substituted lanthanum titanate (BLT) film. • Synthesis Example 13 [In the above formula (I), η = 1 · (Π28, χ = 0.9180, y = • 0.1429, z = 0.6812, α = 0.0768, and the coating solution (Bi: (Ti + A ) 1.04: 1 (mole ratio))] To 1-methoxy-2-propanol, after adding 0.0633 mol lanthanum acetate, 0.2875 mol tetrabutoxy titanium, 0.0143 mol tetrabutoxy germanium , Put it into an eggplant-shaped flask, and heat and stir at 80 ° C. To this was added 0.3121 mol of tributoxybismuth, 0.0296 mol of diisopropoxyphosphonium, and then -33- 200536785 (30) Heat and stir at 60 ° C to synthesize 5 kinds of compound oxygen metal CBLT series compound solution of Bi-Ti-La-Sr_Ge). 0.2000 moles of water was added to the BLT-based composite solution, and the mixture was stirred at room temperature. 03,000 mol of stabilizing agent of ethylhexanoic acid was added thereto, and the mixture was stirred at room temperature, and then heated and concentrated at 60 ° C to obtain 1-methoxy-2 -propanol quilt, 2- A coating solution for forming a dimethoxy-propane-substituted titanate ore (BLT-based) thin film. Example 1 Using the coating solution for forming a bismuth-based ferroelectric thin film produced in Synthesis Examples 1 and 2, the applicability and density were evaluated by the following methods. [Coatability] A 60-nm Pt lower electrode was formed on a 6-inch sand wafer formed with a thermal oxide film SiO 2 having a thickness of 100 μm by a pendulum method. Using the coating solution for forming a bismuth-based ferroelectric thin film produced in Synthesis Examples 1 and 2 on the substrate at 500 rpm and 1 second, followed by spin coating at a speed of 2 000 rpm and 30 seconds. Visually observe the surface state of the coating film. Thereafter, heat treatment was performed at 700 ° C and 30 minutes, and the surface state of the film was observed in the same manner. The results are shown in the table! As shown. (Coated film state before heat treatment after coating) ◎: Uniform coating (film state after heat treatment) ◎: Formed uniform film -34- 200536785 (31) [Density] Synthesis Example 1 was used when formed 2. The 100-nm thermal oxide film Si02 3-inch silicon wafer obtained from the coating solution for forming a bismuth-based ferroelectric thin film was spin-coated at 500 rpm and 1 second, followed by spin coating at 2000 rpm and 30 seconds. The cloth was then heat-treated at 700 ° C. for 30 minutes to obtain a film. Thereafter, the thickness and refractive index of the film were determined using an elliptical symmetry device, and the density was measured. It is found that when the film thicknesses are equal, the higher the refractive index, the higher the density, and the lower the refractive index, the lower the density. The results are shown in Table 1. During the spin coating stage, the surface state of the coating film was visually observed. Thereafter, heat treatment was performed at 700 ° C for 30 minutes, and the surface state of the film was observed in the same visual manner. The results are shown in Table 1. Table 1 Coating liquid for ferroelectric thin film formation. Thickness after coating. Film thickness after firing. 0 m) Refractive index synthesis example 1 ◎ ◎ 47.8 2.414 Synthesis example 2 ◎ ◎ 47.0 2.404 Coating according to Table 1 As a result of the cloth property, the coating liquid of Synthesis Example 1 did not crack, and the film after firing did not form a mist. It is speculated that this result should be the effect that the added alkanolamine can effectively improve the coatability. In Synthesis Example 2, a uniform thin film was formed without any problems. It is speculated that it should be the effect of hydrolysis. Further, from the density results shown in Table 1, it was found that the films obtained from the coating liquids of Synthesis Examples 1 and 2 had a high refractive index and a high density. -35- 200536785 (32) Example 2 [Evaluating the relationship between heating temperature and film crystallization using the coating solution prepared in Synthesis Examples 1 and 2] The coating solution prepared in Synthesis Examples 1 and 2 was used in The heating temperature was 6 500 ° C or 700 ° C to form a thin film, and the relationship between the heating temperature and the crystallization of the thin film was evaluated. Φ means that, first, a 60-nm Pt lower electrode was formed on a 6-inch silicon wafer formed with a thermal oxide film SiO 2 having a thickness of 100 nm by sputtering. After applying the coating liquid prepared in Synthesis Examples 1 and 2 on a substrate having the lower electrode, spin coating was performed at 500 rpm and 1 second using a spin coater, followed by spin coating at 200 Orpm and 30 seconds. , And then dried at 250 ° C for 5 minutes. This coating-drying step is repeated 4 times in total. Finally, in an oxygen environment, heat treatment at 650 ° C, 60 minutes, or 700 ° C, 60 minutes (the first heat treatment) is performed to form a film thickness of 150 nm. BLT series dielectric film. This film was subjected to X-ray winding (XRD) measurement to obtain an XRD curve. The XRD curve of the film prepared according to Synthesis Example 1 is shown in FIG. 1, and the XRD curve of the film prepared according to Synthesis Example 2 is shown in FIG. 2. From the results in Figures 1 and 2, it is known that the film can form the target lanthanum bismuth titanate under the low-temperature firing conditions at 65 ° C and 700 ° C regardless of the coating liquids in Synthesis Examples .1 and 2. BLT) crystal structure. Example 3 • 36- 200536785 (33) [Hysteresis characteristics of a dielectric element obtained by using the dielectric film formed in Example 2] For each film formed in Example 2, a metal mask was used to pass An RF magnetron sputtering method was used to form a P t upper electrode with a film thickness of 300 nm. Secondly, 650 was performed in the oxygen atmosphere at the same temperature as that of Example 2. (:, 30 minutes, or 700 ° C, 30 minutes of recovery annealing treatment (second heat treatment) to form a dielectric element. The hysteresis curve of this dielectric element is shown in Figure 3 · 1, Figure 3-2 It can be seen from Fig. 3-1 and Fig. 3-2 that the films prepared by the coating liquids of Synthesis Examples 1 and 2 can also be fired at a low temperature of 65 ° C and 700 ° C. A BLT ferroelectric thin film with a large polarization (Pr) was formed. Example 4 [Hysteresis characteristics of a dielectric element formed using the coating solution obtained in Synthesis Example 3] According to the same method as in Example 2, The coating liquid prepared according to Synthesis Example 3 was spin-coated at 5000 rpm for 1 second, followed by spin coating at 2000 rpm and 30 seconds, and then at 250 °. Dry for 5 minutes at C. This coating-drying step is repeated 4 times in total. Finally, in an oxygen environment, heat treatment is performed at 650 ° C for 30 minutes (the first heat treatment), followed by 7 0 0 Heat treatment at 60 ° C for 60 minutes (second heat treatment) to form a BLT-based dielectric thin film with a thickness of 150 nm. Next, the upper electrode was formed in the same manner as in Example 3, and Then, it is subjected to a recovery annealing treatment (3rd heat treatment) at 700 ° C to form Yuan • 37-200536785 (34) pieces. The hysteresis curve of this element is shown in Figure 4. According to Figure 4, even if Under low temperature firing conditions at 700 ° C, BLT ferroelectric thin films with large polarization (Pi *) can also be formed. Example 5 [Using the dielectric formed by the coating solution obtained in Synthesis Example 4 Hysteresis and Leakage Characteristics of Body Components] # According to the same method as in Example 2, the coating liquid prepared in Synthesis Example 4 will be rotated at 500 rpm and 1 second, followed by 2000 rpm and 30 seconds. After coating, it was dried at 250 ° C for 5 minutes. After repeating this coating-drying step 5 times, it was heat-treated at 60 ° C and 30 minutes in an oxygen environment (No. 1 time heat treatment), followed by heating at 700 ° C for 60 minutes (second heat treatment) to form a BLT-based dielectric thin film having a thickness of 190 nm. Next, Pt was formed in the same manner as in Example 3. The upper electrode is then subjected to a recovery annealing process (3rd heat treatment) at 700 ° C to form a dielectric element. This dielectric The hysteresis curve of the device is shown in Figure 5, and the leakage characteristics are shown in Figure 6. From Figure 5, it can be seen that even under low temperature baking conditions of 700 ° C, a large polarization (Pr) can be formed. BLT is a ferroelectric thin film. It is also known from FIG. 6 that the device has excellent leakage characteristics. Example 6 [• 38-200536785 of a dielectric device formed using the coating solution obtained in Synthesis Example 5 ( 35) Hysteresis characteristics and leakage characteristics] According to the same method as in Example 2, the coating liquid prepared in Synthesis Example 5 was subjected to spin coating at 500 rpm and 1 second, followed by 2000 rpm and 30 seconds. After the cloth was dried, it was further dried at 2 5 01: 5 minutes. After repeating this coating-drying step 4 times, heat treatment at 65 ° C. for 30 minutes (first heat treatment) was performed in an oxygen environment, followed by 700 ° C. and 60 minutes heat treatment (No. 2 heat treatment) to form a BLT-based dielectric thin film with a thickness of 150 nm. Next, a p t upper electrode was formed in the same manner as in Example 3, followed by a recovery annealing process (third heating process) at 700 ° C to form a dielectric element. The hysteresis curve of this dielectric element is shown in Fig. 7, and the leakage characteristics are shown in Fig. 8. It can be seen from FIG. 7 that even under a low-temperature firing condition at 700 ° C, a BLT-based ferroelectric thin film having a large polarization (Pr) can be formed. It is also known from FIG. 8 that this device has extremely excellent shallow leakage characteristics. Example 7 Using the same coating liquid as the coating liquid capable of forming a ferroelectric thin film, the method of forming a normal dielectric thin film under changing film forming conditions (heating conditions) is shown below. The coating liquid obtained in Synthesis Example 2 was used. The thin film obtained by using this coating solution is a BLT crystalline thin film portion having a strong dielectric property, which can be confirmed in Examples 2 and 3. That is, firstly, a 60 nm Pt lower electrode was formed on a 6-inch -39 · 200536785 (36) inch sand wafer with a thickness of 1000 nm by forming a thermal oxidation film s 2-20 · 200536785 (36) inches. On the substrate having the lower electrode, the coating solution prepared in Synthesis Example 2 using a spin coater was spin-coated at 5000 rpm, 1 second, 2000i * pm, and 30 seconds. The oxygen ring V * is heated at 600 ° C, 60 minutes, or 650 ° C, 60 minutes. The coating was repeated 4 times-the heat treatment step was performed in an oxygen environment, and then the heat treatment was performed at 65 ° C for 60 minutes (heat treatment) to form a BLT-based dielectric with a film thickness of 150 nm. The film was X-rayed. Diffraction (XRD) measurement, XRD was obtained, and the results are shown in FIG. 9. It is known from FIG. 9 that the coating liquid of Synthesis Example 2 of Example 2 and 3 having the crystal structure of the target titanium crystal structure is formed. It has a high non- # Example 8 [Hysteresis and Leakage Characteristics of a Dielectric Formed Using the Dielectric Film Obtained in Example 7] ^ The thin film formed in Example 7 is passed through a metal photomask to A controlled sputtering method is used to form a Pt electrode with a diameter of 200 // m and a film thickness of 300 nm. Next, in this oxygen environment, recovery and recycling at 650 ° C (third heat treatment) was performed. The recovered annealed line of the dielectric element is shown in Fig. 10. ， 将 依 ， 下 境 ， 理 （后 后 ， (2 thin film. Curves' Lanthanum Bismuth acid shows the crystalline electric body element RF magnetic upper electric fire treatment hysteresis curve -40- (37) 200536785 by Fig. 10 shows that the coating liquid of Synthesis Example 2 showing the ferroelectric thin film of Examples 2 and 3 is changed by heating (after firing, even at a low-temperature firing condition of 65 ° C). It is possible to form a dielectric thin film with% electrical properties, and it is known from FIG. 11 that the thin dielectric element using the thin film has excellent leakage characteristics. Example 9 0 [Example of metal composition with constant dielectric properties A 60-nm Pt lower electrode was formed on a 6-inch SiO 2 film having a thickness of 100 nm by sputtering, and a spin coater was used to synthesize examples 6 to 13 on a substrate having the lower electrode. The obtained coating solution was dried at 500 rpm, 1 piece, followed by spin coating at 200 Orpm, 30 seconds, and then dried at 250 ° C for 5 minutes. After 4 times of coating-drying, In an oxygen environment, heat at 65 0 ° C for 30 minutes # 1 heat treatment), followed by 65 (TC, 60 minutes plus ( 2 heat treatment) to form a BLT-based samarium thin film with a thickness of 140 nm. This film was subjected to X-ray diffraction (XRD) measurement, and the curve is shown in Fig. 12. From Fig. 12, it is known that In the case of using any of Synthesis Examples 6 to 13, it was also confirmed that the crystallinity of the lanthanum bismuth titanate was reduced and the amorphous state was increased under a low-temperature firing condition at 65 ° C. Example I 0 Shixi wafers produced by the conventional dielectric film method are prepared with a constant dielectric film, which will be processed in a second step and then dried (the first heat-treated dielectric | XRD coating liquid film • 41- 200536785 (38) [Use Hysteresis characteristics and leakage characteristics of a dielectric element formed from the dielectric thin film obtained in Example 9] v For the thin film formed in Example 9, the coating liquids prepared in Synthesis Examples 9 to 11 were used. The formed dielectric thin film was formed with a metal mask and a Pt upper electrode with a diameter of 200 0 // m and a film thickness of 300 nm by a RF magnetron plating method. Next, in the oxygen environment , At a temperature of 650 ° C which is the same temperature as that of the treatment in Example 9, anneal annealing treatment (the third heat treatment The hysteresis curves and leakage characteristics of the respective dielectric thin films after recovery annealing are as shown in the following figures. In addition, the dielectric constants of the coating liquids of Synthesis Examples 9 to 11 are shown in Table 2. Figure 13: Synthesis Hysteresis curve of a dielectric element formed by the coating liquid of Example 9. Figure 14: Leakage characteristics of a dielectric element formed by the coating liquid of Synthesis Example 9. ® Figure 15: Synthesis Example 1 Hysteresis curve of a dielectric element formed by a coating solution of 0. Figure 16: Leakage characteristics of a dielectric element formed by the coating liquid of Synthesis Example 10. Figure 17: Hysteresis curve of a dielectric element formed by the coating liquid of Synthesis Example 11; Fig. 18 · Leakage characteristics of a dielectric element formed by the coating liquid of Synthesis Example 11 1. -42- 200536785 (39) Table 2 Dielectric constant U of the coating liquid for forming a dielectric thin film) Synthesis Example 9 490 Synthesis Example 1 〇380 Synthesis Example 1 1 360 Under low temperature firing conditions of 0 ° C, a dielectric film with constant dielectric properties can also be formed. It was also found that the BLT dielectric film had excellent leakage characteristics and had a high dielectric constant. When the coating liquids of Synthesis Examples 6 to 8 and 12 to 13 other than the above contents were prepared for the dielectric element, it was learned that the aforementioned BLT-based dielectric film also has constant dielectric properties and excellent leakage characteristics. , With high dielectric constant. As shown above, using a coating liquid obtained from a specific alkoxy metal raw material can produce a normal dielectric material with a good high dielectric constant (low leakage current, high dielectric constant). In addition, when it is used as a composite metal alkoxide, it can have good coating properties, can form a dense film, stabilize the metal composition ratio, and can suppress the phenomenon that the metal composition ratio in the film changes, and has excellent operation. (Not easily affected by the environment such as humidity), stable (storage) coating liquid. In addition, a coating liquid using a specific composite metal alkoxide material can be formed at a low temperature (below 70 0 ° C) with good high dielectric properties (low leakage current, high permittivity), and strong dielectric properties ( Residual polarization (larger residual polarization, etc.), and it is a kind of metal composition with good coating properties, which can form a dense film, and stabilization, and the metal composition ratio which can suppress the film -43- 200536785 (40) Examples of changes in the phenomenon, and coating liquids with excellent operability (not easily affected by the environment such as humidity) and stability (storability). In addition, when a hydrolysate is used, a stable metal composition ratio can be obtained, and a phenomenon that a change in the metal composition ratio in a thin film can be more suppressed. In addition, when an alkanolamine is added, the coatability can be further improved. The present invention is to provide a coating solution for forming a bismuth-based dielectric film which can form a stable metal composition ratio and can suppress the phenomenon that the metal composition ratio in the film is changed. The present invention also provides a coating solution for forming a bismuth-based dielectric thin film having a constant dielectric property with a low leakage current and a high dielectric constant. In the coating liquid of the present invention, when the metal composition ratio of the coating liquid is controlled, or when the conditions for forming a thin film are controlled, the formation of a normal dielectric material and a ferroelectric body can be performed. Therefore, the coating liquid of the present invention is very suitable for use in, for example, DRAM as a normal dielectric material or nonvolatile memory as a ferroelectric material, and is widely applicable to characteristics required for semiconductor devices. [Brief description of the figure] FIG. 1 is an XRD curve diagram of a dielectric thin film formed by using the coating liquid of Synthesis Example 1. FIG. Fig. 2 is an XRD curve diagram of a dielectric film formed using the coating solution of Synthesis Example 2. Fig. 3-1 is a hysteresis curve of a dielectric element formed using the coating liquid of Synthesis Example 1. -44- 200536785 (41) Figure 3-2 is a hysteresis curve of a dielectric element formed using the coating solution of Synthesis Example 2. Fig. 4 is a hysteresis curve diagram of a dielectric element formed using the coating liquid of Synthesis Example 3. Fig. 5 is a hysteresis curve diagram of a dielectric element formed using the coating solution of Synthesis Example 4. Fig. 6 is a leakage characteristic diagram of a dielectric element formed using the coating solution of Synthesis Example 4. Fig. 7 is a hysteresis curve diagram of a dielectric element formed using the coating solution of Synthesis Example 5. Fig. 8 is a leakage characteristic diagram of a dielectric element formed using the coating liquid of Synthesis Example 5. Fig. 9 is an XRD graph of a dielectric thin film (normally dielectric) formed using the coating liquid of Synthesis Example 2. FIG. 10 is a hysteresis curve diagram of a dielectric element (normally dielectric) formed using the coating liquid of Synthesis Example 2. FIG. FIG. 1 is a leakage characteristic diagram of a dielectric element (normally dielectric) formed using the coating liquid of Synthesis Example 2. FIG. Fig. 12 is an XRD curve diagram of a dielectric thin film formed by using the coating liquid of Synthesis Example 6 to 13. Fig. 13 is a hysteresis curve of a dielectric element formed using the coating liquid of Synthesis Example 9. Fig. 14 is a leakage characteristic diagram of a dielectric element formed using the coating liquid of Synthesis Example 9. -45- 200536785 (42) Fig. 15 is a hysteresis curve of a dielectric element formed by using the coating liquid of Synthesis Example 10. FIG. 16 is a leakage characteristic diagram of a dielectric element formed using the coating liquid of Synthesis Example 10. FIG. Fig. 17 is a hysteresis curve diagram of a dielectric element formed using the coating liquid of Synthesis Example 11. FIG. 18 is a leakage characteristic diagram of a dielectric element formed using the coating liquid of Synthesis Example 11. FIG.

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Claims (1)

200536785 (1) X. Patent application scope 1. A coating liquid, which is a coating liquid for forming a ferroelectric bismuth-based dielectric thin film containing a composite metal oxide represented by the following formula (I). It is a compound alkoxy metal containing at least two alkoxy metals of Bi and Ti, {Β ， 4-χ Λ (Laz 'Β) .ζ) χ} η (Tl3-y' Ay) 〇ΐ2 + α ( Ϊ) (where A is at least one metal element selected from V, Cr, Mn, Si, Ge, Zr, Nb, Ru, Sn, Ta, and W, and B is a rare earth element not containing lanthanum At least one metal element selected from the group consisting of Ca, Sr, and Ba, and x, y, and z are each 0Sx &lt; 4, 0Sy'0.3, 0 &lt; zSl, η is a number from 0.7 to 1.4, and α is a number The price determined by the metal composition ratio). 2. The coating liquid according to item 1 of the scope of the patent application, wherein the coating liquid is a composite alkoxy metal containing at least two alkoxy metals of B i and Ti, which uses water or water and A gel / sol solution obtained by a catalyst undergoing a hydrolysis-partial condensation treatment. 3. For example, the coating liquid of the scope of application of the patent, wherein the coating liquid is further added with an alkanolamine. 4. The coating liquid according to item 1 of the scope of patent application, wherein in the above formula (I), X is a number shown by 0 &lt; x &lt; 4. 5. The coating liquid according to item 1 of the scope of patent application, wherein, in the above formula (I), z is 0 &lt; ζ &lt;; [the number shown. 6. The coating liquid according to item 丨 of the patent application scope, wherein, in the above formula (I), y is a number represented by 0 &lt; yg 0.3. -47- (2) (2) 200536785 '· The coating liquid according to item [Scope of application for patent], wherein in the above formula (Ϊ), the metal element A is Ge, and y = 0.05 to 0.20 Number. 8. If the coating liquid of the first patent application scope, the ratio of the contained Bi, Ti and A metal elements (which also does not include a metal element) is Bi: (Ti + A) = 1 〇7 to 1.15: 1 (Molar ratio) ratio. 9 · A coating liquid, which is a coating liquid for forming a bismuth-based dielectric thin film having a normal dielectric characteristic, characterized in that it contains a composite alkoxy metal formed of at least two alkoxy metals of Bi and Ti, Or it contains a mixed metal alkoxide obtained by mixing at least bismuth alkoxide and titanium alkoxide. 10. The coating liquid according to item 9 of the scope of patent application, which is a coating liquid for forming a normal dielectric bismuth-based dielectric thin film containing a composite metal oxide represented by the following formula (I), {Bi4.x & gt (Laz ^ Β, .ζ) χ} η (Τι3.γ 'Ay) 012 + a (I) (where A is V, C r, M η, S i, G e, Z r, N b , Ru, Sn, Ta, and W, at least one metal element selected, B is at least one metal element selected from rare earth elements not containing lanthanum, Ca, Sr, and Ba, x, y, z Each is the number shown by 0 $ x &lt; 4, 0gyg0.3, 0 &lt; z $ l, η is a number from 0.7 to 1.4, and α is a valence determined by the metal composition ratio). 1 1. The coating liquid according to item 9 of the scope of patent application, wherein the coating liquid is a composite alkoxy metal containing at least two alkoxy metals such as Bi and Ti, or contains at least bismuth alkoxide and A mixed metal alkoxide obtained by mixing titanium alkoxide, and then hydrolyzed with water, or water and a catalyst-partial-48-200536785 (3) gel / sol solution obtained by condensation treatment. 12. The coating liquid according to item 9 of the application, wherein the coating liquid is further added with an alkanolamine. 13. The coating liquid according to item 10 of the scope of patent application, wherein in the formula (I), X is a number shown by 0 &lt; x &lt; 4. 14. The coating liquid according to item 10 of the scope of patent application, wherein in the above formula (I), z is a number represented by 0 &lt; ζ &lt; 1. 15. The coating liquid according to item 10 of the scope of patent application, wherein in the above formula (I), y is a number represented by 0 and yS0.3. 1 6 · If the coating solution in the scope of patent application No. 10, the proportion of the Bi, Ti and A metal elements (which also does not include A metal elements), is Bi: (Ti + A) = Ratio of 0.90 to 1.06: 1 (Molar ratio). 1 7 · A method for forming a conventional dielectric bismuth-based dielectric thin film, which is characterized in that a coating liquid with a patent application scope of item 9 is coated on a substrate and is subjected to heat drying treatment without applying The heat treatment (1st heat treatment) at 5 00 to 7 00 ° C to form a coating film, and as needed, the aforementioned steps of coating to heat treatment (first heat treatment) are repeated several times to form a coating film. The laminate is then heat-treated at 600 to 700 ° C (second heat treatment). 18 · —A conventional dielectric bismuth-based dielectric film containing a composite metal oxide represented by the following formula (I): {Βΐ4-χΛ (Laz 'B) -z) x} n (Tl3-y' Ay ) 〇! 2 + α (I) (where A is V, Cr, Mn, Si, Ge, Zr, Nb, Ru, • 49-200536785 (4) at least 1 selected from Sn, Ta, and W A metal element containing a rare earth element of lanthanum, a selected element of Ca, Sr, and Ba, x, y, and z are each a number shown by 0gx &lt; 4, 0S], η is a number from 0.7 to 1.4, α Is a fixed price). 19 · If the ratio of Bi, Ti and Α metal elements (including non-visible) in the thin film of the 18th patent application range is Bi: (Ti + A) = 0.90 to ratio. 2．If the thinning of the patent scope No. 18 or 19 is applied, the coating solution of the patent scope No. 9 is obtained by coating on the base and baking it. : Prime, B is composed of at least one kind of gold β 0.3,0 &lt; zS 1 metal composition, which is not included, among which, the content of A metal element 1.06: 1 (Molar film, which will be the application board On the electrode, -50-