JP5008379B2 - Zinc compound, raw material for forming thin film containing zinc compound, and method for producing thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To impart suitable properties such as volatility and melting point-lowering property to a bisalkoxy zinc compound having sufficient reactivity as a precursor for supplying zinc to thin films to provide a zinc compound especially suitable as a raw material for CVD. <P>SOLUTION: The zinc compound is represented by general formula (1) (wherein, one of R<SP>1</SP>and R<SP>2</SP>is ethyl or isopropyl, and the other is H, methyl, ethyl or isopropyl; R<SP>3</SP>is a 1 to 4C alkyl). <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a novel zinc compound having a specific structure, a raw material for forming a thin film containing the novel zinc compound, and a method for producing a thin film using the raw material for forming a thin film.

  A thin film containing zinc has various properties such as optical properties, electrical properties, and catalytic activity, and is used as a member of electronic components and optical components.

  Examples of the method for producing the above thin film include flame deposition, sputtering, ion plating, MOD such as coating pyrolysis and sol-gel, and chemical vapor deposition. Since it has many advantages such as being excellent in performance, suitable for mass production, and capable of hybrid integration, chemical vapor deposition including the ALD (Atomic Layer Deposition) method (hereinafter simply referred to as CVD) Method) is the optimal manufacturing process.

  In the CVD method, many β-diketone complexes have been studied from the viewpoint of stability and safety as precursors for supplying zinc atoms to a thin film. For example, Patent Documents 1 and 2 disclose a CVD method using bis (pentane-2,4-dionato) zinc, and Non-Patent Document 1 discloses bis (2,2,6,6-tetramethyl). A method using heptane-3,5-dione) zinc has been reported. In Patent Document 3, bis (octane-2,4-dionato) zinc and bis (2,2-dimethyl-6-ethyldecane-3,5-dionato), which are liquid bis (β-diketonato) zinc at 25 ° C. Zinc is disclosed.

  A property required for a compound (precursor) suitable for a raw material used in the CVD method is that a thin film is easily formed by a chemical reaction such as oxidation during the deposition of the thin film. Although the above β-diketone complex of zinc is a stable compound and is superior in terms of supply of the CVD process, the reactivity during the deposition of the thin film is not always satisfactory.

Non-Patent Document 2 discloses various bisalkoxyzinc compounds as a precursor of a zinc oxide thin film, focusing on solubility and volatility. Specific compounds include Zn (OCEt ₃ ) ₂ , Zn (OCEt ₂ Me) ₂ using a sterically bulky tertiary alcohol as a ligand, and an alcohol having a nucleophilic group at the terminal. Zn (OCH ₂ CH ₂ OMe) ₂ , Zn (OCH ₂ CH ₂ NMe ₂ ) ₂ , Zn (OCHMeCH ₂ NMe ₂ ) _{2 and the} like used as a child are disclosed [Et represents ethyl, Me represents methyl] . Since these bisalkoxyzinc compounds are not sufficiently volatile, they are not always satisfactory as raw materials for CVD with precursor volatilization.

Japanese Patent Publication No. 6-64738 (particularly [Claim 9]) JP 2003-236376 A (particularly [Example]) Japanese Patent Laying-Open No. 2005-350423 (particularly [Claim 1] to [Claim 6]) Microelectron. Eng., 29 (1-4), 169-72 (1995) Inorg. Chem. 1990, 29, 4646-4652

  Therefore, the problem to be solved by the present invention is to impart more suitable properties such as volatility and low melting point to the bisalkoxyzinc compound having sufficient reactivity as a precursor for supplying zinc to the thin film. The object is to provide a zinc compound suitable as a raw material for CVD.

  As a result of repeated studies, the present inventors have found that a zinc compound having a specific structure can solve the above problems, and have reached the present invention.

  That is, this invention solves the said subject by providing the zinc compound represented by following General formula (1).

（式中、Ｒ¹及びＲ²は、各々独立にエチル基又はイソプロピル基を表し、Ｒ³は、炭素数１〜４のアルキル基を表す。）

(In the formula, R ¹ and R ² each independently represent an ethyl group or an isopropyl group , and R ³ represents an alkyl group having 1 to 4 carbon atoms.)

Moreover, this invention provides the raw material for thin film formation containing the said zinc compound.
The present invention also provides a method for producing a thin film in which a vapor containing a zinc compound obtained by vaporizing the thin film forming raw material is introduced onto a substrate, and this is decomposed and / or chemically reacted to form a thin film on the substrate. A method is provided.

  According to the present invention, it is possible to provide a zinc compound having properties such as reactivity, volatilization characteristics, and melting point suitable as a raw material for CVD.

The zinc compound of the present invention represented by the general formula (1) exhibits reactivity suitable as a thin film precursor, and is particularly suitable as a raw material for CVD. The zinc compound of the present invention represented by the general formula (1) may have a stereoisomer, and a coordination product in which an OR ³ oxygen molecule is coordinated to a zinc element in the same molecule to have a ring structure. May be formed, and molecules may associate to form an aggregate.
For example, as an association state of the zinc compound of the present invention, a structure represented by the following general formula (1-1) can be given as an example in which two molecules are associated.

  The zinc compound of the present invention is not distinguished by these stereoisomers, coordination bodies, and aggregates, but includes any of them. In the following, it is shown representatively in a form without intramolecular coordination and association.

In the general formula (1), examples of the alkyl group having 1 to 4 carbon atoms represented by R ³ include methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, tertiary butyl, and isobutyl.

Specific examples of the zinc compound of the present invention represented by the general formula (1) include the following compound Nos. 1-No. 21.
In addition, the following compound No. 1-No. 21, Me represents methyl, Et represents ethyl, Pr represents propyl, iPr represents isopropyl, Bu represents butyl, sBu represents second butyl, tBu represents third butyl, and iBu represents isobutyl. In the following description, similar abbreviations are used.

Among the zinc compounds of the present invention represented by the general formula (1), those in which R ¹ and R ² are each independently an ethyl group or an isopropyl group are preferable because the melting point is particularly low.

The zinc compound of the present invention represented by the general formula (1) is not particularly limited by the production method, and can be produced by applying a known reaction. As a production method, a method in which an alcohol represented by HO—CR ¹ R ² CH ₂ OR ³ is reacted with a dialkylzinc such as dimethylzinc, diethylzinc or dipropylzinc, bis [bis (trimethylsilyl) amino] zinc, bis [ A method of reacting an alcohol represented by HO—CR ¹ R ² CH ₂ OR ³ with a zinc amide compound such as diethylamino] zinc, the presence of a basic reactant with zinc chloride and HO—CR ¹ R ² CH ₂ OR ³ The method of making it react below is mentioned.

  The zinc compound of the present invention can be suitably used as a thin film forming raw material by a MOD method such as a coating pyrolysis method or a sol-gel method, in addition to being suitably used as a thin film forming raw material by a CVD method or the like having a vaporization step. Can also be used as a zinc oxide powder raw material, an organic synthesis catalyst, a polymer compound synthesis catalyst, and the like.

  The thin film forming raw material of the present invention contains the above-described zinc compound of the present invention as a thin film precursor, and the form thereof is a method for producing a thin film to which the thin film forming raw material is applied (for example, coating pyrolysis). Method, MOD method such as sol-gel method, CVD method including ALD). The raw material for forming a thin film of the present invention is particularly useful as a raw material for CVD having a step of vaporizing a zinc compound because the zinc compound of the present invention which is a precursor has a low melting point and is volatile.

  In the case where the thin film forming raw material of the present invention is a chemical vapor deposition (CVD) raw material, the form thereof is appropriately selected depending on a method such as a CVD transporting / supplying method used.

  As the transport and supply method described above, the CVD raw material is vaporized by heating and / or depressurizing in the raw material container, and introduced into the deposition reaction section together with a carrier gas such as argon, nitrogen, and helium used as necessary. There is a gas transport method and a liquid transport method in which a CVD raw material is transported to a vaporization chamber in a liquid or solution state, vaporized by heating and / or decompressing in the vaporization chamber, and introduced into a deposition reaction section. In the case of the gas transport method, the zinc compound of the present invention represented by the above general formula (1) itself is a raw material for CVD, and in the case of the liquid transport method, it is represented by the above general formula (1) heated above the melting point. The zinc compound of the present invention itself or a solution obtained by dissolving the zinc compound in an organic solvent is a raw material for CVD.

  In the multi-component CVD method for producing a multi-component thin film, a CVD raw material is vaporized and supplied independently for each component (hereinafter sometimes referred to as a single source method), a multi-component raw material There is a method of vaporizing and supplying a mixed raw material prepared by mixing in advance with a desired composition (hereinafter sometimes referred to as a cocktail sauce method). In the case of the cocktail sauce method, a mixture of the zinc compound of the present invention represented by the above general formula (1) and another precursor or a mixed solution obtained by adding an organic solvent to the mixture is a raw material for CVD.

  The organic solvent used for the above-mentioned CVD raw material is not particularly limited, and a known general organic solvent can be used. Examples of the organic solvent include: acetates such as ethyl acetate, butyl acetate and methoxyethyl acetate; ethers such as tetrahydrofuran, tetrahydropyran, morpholine, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, dibutyl ether and dioxane Ketones such as methyl butyl ketone, methyl isobutyl ketone, ethyl butyl ketone, dipropyl ketone, diisobutyl ketone, methyl amyl ketone, cyclohexanone, methylcyclohexanone; hexane, cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, heptane, octane, Hydrocarbons such as toluene and xylene; 1-cyanopropane, 1-cyanobutane, 1- Hydrocarbons having a cyano group such as ananohexane, cyanocyclohexane, cyanobenzene, 1,3-dicyanopropane, 1,4-dicyanobutane, 1,6-dicyanohexane, 1,4-dicyanocyclohexane, 1,4-dicyanobenzene Pyridine and lutidine, which are used alone or as a mixed solvent of two or more kinds depending on the solubility of the solute, the relationship between the use temperature and boiling point, the flash point, and the like. When these organic solvents are used, the total amount of the precursor components in the organic solvent is preferably 0.01 to 2.0 mol / liter, particularly 0.05 to 1.0 mol / liter. .

  In addition, in the multi-component CVD method using a single source method or a cocktail source method, other precursors used together with the zinc compound of the present invention represented by the general formula (1) are not particularly limited, A well-known general precursor used for a CVD raw material can be used.

  As said other precursor, one type or two or more types selected from organic coordination compounds such as alcohol compounds, glycol compounds, β-diketone compounds, cyclopentadiene compounds and organic amine compounds, and silicon, boron, phosphorus or A compound with a metal is mentioned. Metal species include group 1 elements such as lithium, sodium, potassium, rubidium and cesium, group 2 elements such as beryllium, magnesium, calcium, strontium and barium, scandium, yttrium and lanthanoid elements (lanthanum, cerium, praseodymium, neodymium, Promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium), group 3 elements such as actinoid elements, group 4 elements of titanium, zirconium, hafnium, group 5 elements of vanadium, niobium, tantalum , Chromium, molybdenum, tungsten group 6 elements, manganese, technetium, rhenium group 7 elements, iron, ruthenium, osmium group 8 elements, cobalt, rhodium, iridium Group 9 elements, nickel, palladium, platinum group 10 elements, copper, silver, gold group 11 elements, cadmium, mercury group 12 elements, aluminum, gallium, indium, thallium group 13 elements, germanium, tin, lead 14 group elements, arsenic, antimony, group 15 elements of bismuth, and group 16 elements of polonium.

  In the case of the single source method, the other precursor is preferably a compound similar to the zinc compound of the present invention represented by the general formula (1) in the behavior of thermal decomposition and / or oxidative decomposition. In the case of the method, in addition to the similar behavior of thermal decomposition and / or oxidative decomposition, those which do not cause alteration due to chemical reaction during mixing are preferable.

  Moreover, the raw material for forming a thin film of the present invention may contain a nucleophilic reagent as needed to impart stability to the zinc compound of the present invention and other precursors. Examples of the nucleophilic reagent include ethylene glycol ethers such as glyme, diglyme, triglyme, and tetraglyme, 18-crown-6, dicyclohexyl-18-crown-6, 24-crown-8, and dicyclohexyl-24-crown. -8, crown ethers such as dibenzo-24-crown-8, ethylenediamine, N, N′-tetramethylethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, 1,1,4,7, 7-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetramine, polyamines such as triethoxytriethyleneamine, cyclic polyamines such as cyclam, cyclen, pyridine, pyrrolidine , Piperidine, morpholine, N-methylpyrrolidine, N-methylpiperidine, N-methylmorpholine, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, oxazole, thiazole, oxathiolane and other heterocyclic compounds, methyl acetoacetate, ethyl acetoacetate Β-ketoesters such as acetoacetate-2-methoxyethyl or β-diketones such as acetylacetone, 2,4-hexanedione, 2,4-heptanedione, 3,5-heptanedione, and dipivaloylmethane. The amount of these nucleophilic reagents used as stabilizers is preferably 0.1 mol to 10 mol, more preferably 1 to 4 mol, relative to 1 mol of the precursor.

  In the raw material for forming a thin film of the present invention, impurities such as impurity metal elements other than the components constituting the thin film, impurity organics, and impurity halogens such as impurity chlorine are included as much as possible. The impurity metal element content is preferably 100 ppb or less for each element, more preferably 10 ppb or less, and the total amount is preferably 1 ppm or less, more preferably 100 ppb or less. The total amount of impurity organic components is preferably 500 ppm or less, more preferably 50 ppm or less, and still more preferably 10 ppm or less. In addition, since moisture causes generation of particles in the raw material for thin film formation and generation of particles by the CVD method, metal compounds, organic solvents and nucleophilic reagents must be used in order to reduce their respective moisture. It is better to remove moisture as much as possible. The water content of each of the metal compound, organic solvent and nucleophilic reagent is preferably 10 ppm or less, more preferably 1 ppm or less.

  In addition, the raw material for forming a thin film of the present invention can be used to reduce or prevent particle contamination of a thin film to be produced. In the particle measurement by a light scattering submerged particle detector in a liquid phase, The number is preferably 100 or less in 1 ml of liquid phase, more preferably the number of particles larger than 0.2 μm is 1000 or less in 1 ml of liquid phase, and the number of particles larger than 0.2 μm is liquid. More preferably, no more than 100 per 1 ml of phase.

  The thin film manufacturing method of the present invention uses the thin film forming raw material of the present invention, and vaporizes the zinc compound of the present invention represented by the general formula (1) and other precursors used as necessary. This is by a CVD method in which vapor and a reactive gas used as necessary are introduced onto the substrate, and then a precursor is decomposed and / or chemically reacted on the substrate to grow and deposit a thin film on the substrate. There are no particular restrictions on the method for transporting and supplying raw materials, the deposition method, the production conditions, the production equipment, etc., and well-known general conditions and methods can be used.

  Examples of the reactive gas used as needed include, for example, oxygen, ozone, nitrogen dioxide, nitric oxide, water vapor, hydrogen peroxide, formic acid, acetic acid, acetic anhydride and the like as oxidizing gases. In addition, hydrogen is exemplified as a reducing substance, and examples of those that produce nitride include organic amine compounds such as monoalkylamine, dialkylamine, trialkylamine, and alkylenediamine, hydrazine, ammonia, and the like. Hydrogen sulfide is mentioned as what manufactures a sulfide.

  Examples of the transport and supply method include the gas transport method, the liquid transport method, the single source method, and the cocktail sauce method.

  In addition, as the above deposition method, the source gas, or the thermal CVD in which the source gas and the reactive gas are reacted only by heat to deposit a thin film, the plasma CVD using heat and plasma, the photo CVD using heat and light, Examples include optical plasma CVD using heat, light and plasma, and ALD (Atomic Layer Deposition) in which the deposition reaction of CVD is divided into elementary processes and deposition is performed stepwise at the molecular level.

  Moreover, as said manufacturing conditions, reaction temperature (substrate temperature), reaction pressure, a deposition rate, etc. are mentioned. About reaction temperature, 160 degreeC or more which is the temperature which the zinc compound of this invention fully reacts is preferable, and 250 to 800 degreeC is more preferable. The reaction pressure is preferably from atmospheric pressure to 10 Pa, more preferably from atmospheric pressure to 100 Pa. The combination of the deposition method and the reaction pressure is arbitrary, for example, reduced pressure thermal CVD, reduced pressure plasma CVD, reduced pressure light CVD, reduced pressure light plasma CVD, atmospheric pressure thermal CVD, atmospheric pressure plasma CVD, atmospheric pressure light CVD, atmospheric pressure light. Plasma CVD is possible. The deposition rate can be controlled by the raw material supply conditions (vaporization temperature, vaporization pressure), reaction temperature, and reaction pressure. When the deposition rate is large, the properties of the obtained thin film may be deteriorated. When the deposition rate is small, productivity may be problematic. Therefore, the deposition rate is preferably 0.5 to 5000 nm / min, and more preferably 1 to 1000 nm / min. In the case of ALD, the number of cycles is controlled so as to obtain a desired film thickness.

  Further, in the method for producing a thin film of the present invention, after the thin film is deposited, an annealing treatment may be performed to obtain better electrical characteristics, and a reflow process may be provided if step filling is necessary. . The temperature in this case is usually 500 to 1200 ° C, preferably 600 to 1000 ° C.

  The thin film produced by the method for producing a thin film of the present invention using the raw material for forming a thin film of the present invention can be prepared by appropriately selecting a precursor of other components, a reactive gas, and production conditions, so that a metal, an alloy, a sulfide, Desired types of thin films such as oxide ceramics, nitride ceramics, and glass can be obtained. The types of thin films produced include, for example, zinc, ZnSe, zinc oxide, zinc sulfide, zinc-indium composite oxide, lithium-added zinc oxide, zinc-added ferrite, lead-zinc composite oxide, lead-zinc-niobium composite. Examples of oxides, bismuth-zinc-niobium composite oxide, barium-zinc-tantalum composite oxide, and tin-zinc composite oxide include, for example, semiconductors, transparent conductors, light emitters, Examples include phosphors, photocatalysts, magnetic materials, conductors, high dielectric materials, ferroelectric materials, piezoelectric materials, microwave dielectric materials, optical waveguides, optical amplifiers, optical switches, electromagnetic wave shields, solar cells, and the like.

  Hereinafter, the present invention will be described in more detail with examples and evaluation examples. However, the present invention is not limited by the following examples.

Example 1 Compound No. 1 Production of 3 Into a reaction flask substituted with dry argon, 8 g of bis [bis (trimethylsilylamino)] zinc and 30 ml of hexane were charged, and 5.61 g of 3-methoxymethyl-3-pentanol was slowly added dropwise thereto at room temperature. After stirring at room temperature for 2 hours, the solvent was removed to obtain a white solid. The obtained white solid was purified by distillation, and 2.2 g of a purified solid product was obtained from a fraction of 178 ° C./0.15 Torr. The obtained solid was analyzed as follows to confirm that it was the target product.
(analysis)
Elemental analysis (CHN: CHN analyzer, metal analysis: ICP)
Carbon 50.4 mass% (theoretical value 51.30%), hydrogen 9.1 mass% (theoretical value 9.23%), zinc 19.8 mass% (theoretical value 19.94%)
・¹ H-NMR (solvent: heavy benzene)
The chart is shown in FIG.

Example 2 Compound No. Preparation of 19 A reaction flask substituted with dry argon was charged with 100 g of bis [bis (trimethylsilylamino)] zinc and 400 ml of hexane, and 92.5 g of 3-ethoxymethyl-2,4-dimethyl-3-pentanol was added thereto at room temperature. Slowly dripped. After stirring at room temperature for 2 hours, the solvent was removed to obtain a white solid. The resulting white solid was purified by distillation, and 42 g of a purified solid product was obtained from a 165 ° C./0.1 Torr fraction. The obtained solid was analyzed as follows to confirm that it was the target product.
(analysis)
Elemental analysis (CHN: CHN analyzer, metal analysis: ICP)
Carbon 54.5 mass% (theoretical value 58.3%), hydrogen 10.0 mass% (theoretical value 10.3%), zinc 15.9 mass% (theoretical value 15.9%)
・¹ H-NMR (solvent: heavy benzene)
The chart is shown in FIG.

From the distillation purification conditions in Examples 1 and 2 above, compound no. 3 is 178 ° C., 0.15 Torr, Compound No. It can be seen that 19 volatilizes at 165 ° C. and 0.1 Torr. On the other hand, according to Non-Patent Document 2 , Zn (OCEt ₃ ) ₂ , Zn (OCEt ₂ Me) ₂ , Zn (OCH ₂ CH ₂ OMe) ₂ , Zn (OCH ₂ CH ₂ NMe ₂ ) ₂ , Zn (OCHMeCH _2). The evaporation point of NMe ₂ ) ₂ is 10 ⁻⁴ Torr and is in the range of 100 to 225 ° C. From the above, the compound No. 1 which is the zinc compound of the present invention is used. 3 and compound no. No. 19 was confirmed to have good volatility.

[Evaluation Example 1]
Compound Nos. Obtained in Examples 1 and 2 above. 3 and compound no. 19 and Comparative Compound 1 which is an alkoxide having an ether group at the terminal shown below were measured for TG-DTA. The measurement conditions are an Ar flow rate of 100 ml / min, a temperature increase rate of 10 ° C./min, and the measurement sample amounts are as described in Table 1. Table 1 shows the measurement results of the 50 mass% weight loss temperature and the endothermic start temperature of DTA, and the mass reduction.

  From Table 1 above, Comparative Compound 1 having a bulky alcohol having an ether group at the end as a ligand has a structure similar to that of the zinc compound of the present invention. 3, Compound No. Compared to 19, it is inferior in volatility despite its low molecular weight. Further, it is solid at least below 266 ° C. On the other hand, the zinc compound of the present invention has a particularly good volatility and a low melting point, and is therefore suitable as a precursor for a CVD raw material.

Example 3 Production of Zinc Oxide Thin Film A zinc oxide thin film was produced on a sapphire substrate under the following production conditions using the CVD apparatus shown in FIG. About the manufactured thin film, the film thickness and film | membrane composition were confirmed with the fluorescent X ray. The results are shown below.
(Production conditions)
Raw material for zinc CVD: Compound No. 19 ethylcyclohexane solution (concentration: 0.25 mol / kg), raw material flow rate: 0.4 sccm, vaporization chamber temperature: 220 ° C., vaporizer pressure: 800 Pa, carrier gas: argon 150 sccm, oxidizing gas: oxygen 1000 sccm, reaction pressure : 800 Pa, reaction temperature (base temperature): 500 ° C., film formation time: 60 minutes.
(result)
Film thickness: 1145 nm, film composition: zinc oxide

1 shows a ¹ H-NMR chart of the zinc compound (Compound No. 3) of the present invention obtained in Example 1. FIG. 2 shows a ¹ H-NMR chart of the zinc compound of the present invention (Compound No. 19) obtained in Example 2. FIG. 3 is a schematic diagram showing a CVD apparatus used in the thin film manufacturing method of the present invention used in Example 3.

Claims (3)

A zinc compound represented by the following general formula (1).

(In the formula, R ¹ and R ² each independently represent an ethyl group or an isopropyl group , and R ³ represents an alkyl group having 1 to 4 carbon atoms.) A raw material for forming a thin film comprising the zinc compound according to claim 1 . A method for producing a thin film, wherein a vapor containing a zinc compound obtained by vaporizing the thin film forming raw material according to claim 2 is introduced onto a substrate, and this is decomposed and / or chemically reacted to form a thin film on the substrate. .

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