TWI842950B - Thin-film-forming raw material for atomic-layer deposition method, and method for producing zinc-containing thin film using the same - Google Patents

Abstract

The present invention is a raw material for forming a thin film by atomic layer deposition method, containing a zinc compound represented by the following general formula (1). (wherein, ^R1 and ^R2 each independently represent an alkyl group having 1 to 5 carbon atoms, a trimethylsilyl group or a trifluoromethyl group, but ^R1 and ^R2 are different groups), and a method for manufacturing a zinc-containing thin film using an atomic deposition method, comprising the steps of introducing a raw material gas for vaporizing the aforementioned thin film forming raw material into a processing environment, allowing the zinc compound in the raw material gas to be deposited on the surface of a substrate to form a precursor layer, and introducing a reactive gas into the processing environment, allowing the aforementioned precursor layer to react with the aforementioned reactive gas.

Description

Thin film forming raw material for atomic layer deposition method and method for producing zinc-containing thin film using the same

The present invention relates to a thin film forming raw material for atomic layer deposition containing a zinc compound having a specific structure and a method for producing a zinc-containing thin film using the same.

Zinc is used as a component for constituting a compound semiconductor and as a thin film forming raw material for producing a zinc-containing thin film, and various compounds have been reported.

Examples of thin film manufacturing methods include sputtering, ion plating, MOD such as coating thermal decomposition or sol-gel method, and CVD. Among these, atomic layer deposition (hereinafter sometimes referred to as ALD), which is a type of CVD, is the most suitable manufacturing process due to its advantages such as excellent composition controllability and step coverage, suitability for mass production, and hybrid integration.

Although there are many reports on raw materials that can be used in gas phase thin film forming methods such as CVD and ALD, the temperature range of the thin film forming raw materials applicable to the ALD method, called the ALD window, must be sufficiently wide. It is common knowledge in the technical field that even thin film forming materials that can be used in the CVD method are often not applicable to the ALD method.

In the method for manufacturing a metal-containing thin film, for example, in Patent Document 1, it is proposed that a plurality of metal compounds such as bis(di-tert-butylamino)zinc be used as a raw material for forming a thin film of a metal oxide coating a substrate. Patent Document 2 discloses the use of a raw material for MOCVD generated by reacting a zinc raw material such as dimethylzinc, diethylzinc, triethylamine adduct of dimethylzinc with ammonia, a primary or secondary amine to form a ZnSe film. Non-patent Document 1 discloses the use of an alkyl (dialkylamide) zinc compound as a zinc precursor to manufacture a thin film using the MOCVD method. [Prior Art Document] [Patent Document]

[Patent document 1] Japanese Patent No. 5290488 [Patent document 2] Japanese Patent Publication No. 10-51031 [Non-patent document]

[Non-patent document 1] Polyhedron, Vol.16, No. 20, pp3593-3599, (1997); “The Properties of some volatile alkyl(di-alkylamido) zinc(II) and bis (di-alkylamido)zinc compounds: potential zinc precursors in MOCVD”

[Problems to be solved by the invention]

In addition to being required to have a wide ALD window, the thin film forming raw materials used in the ALD method are also required to have a low melting point, high volatility, react with reactive gases at low temperatures, and be able to produce thin films with good productivity. However, although Patent Document 1 describes the ALD method, it does not specifically describe that zinc compounds can be applied to the ALD method. Patent Document 2 and Non-Patent Document 1 describe various zinc amide compounds as zinc raw materials for ZnSe thin films. However, although these documents disclose a method for producing zinc-containing thin films using zinc amide compounds as raw materials for MOCVD, they do not disclose the use of the ALD method to produce zinc-containing thin films.

Therefore, the purpose of the present invention is to provide a thin film forming raw material of a zinc-containing compound that has a low melting point, high volatility, and can react with a reactive gas at a low temperature and is suitable as a raw material for the ALD method, and a method for producing a zinc-containing thin film that can produce a smooth thin film with good quality with good productivity using the same. [Means for solving the problem]

As a result of repeated and active research, the inventors of the present invention have found that a thin film forming raw material for the ALD method containing a zinc compound having a specific structure can solve the above-mentioned problem, thereby completing the present invention. That is, the present invention provides a thin film forming raw material for the ALD method, which contains a zinc compound represented by the following general formula (1),

In the formula, ^R1 and ^R2 each independently represent an alkyl group having 1 to 5 carbon atoms, a trimethylsilyl group or a trifluoromethyl group, but ^R1 and ^R2 represent different groups.

In the thin film forming raw material of the present invention, preferably, in the above general formula (1), ^R1 is a tertiary alkyl group and ^R2 is a dialkyl group.

Furthermore, in the thin film forming raw material of the present invention, it is more preferred that in the above general formula (1), R ¹ is a tert-butyl group and R ² is an isopropyl group.

The present invention provides a method for manufacturing a zinc-containing thin film using an ALD method, which comprises a first step of introducing a raw material gas for vaporizing a thin film forming raw material used for the ALD method of the present invention into a processing environment, so that a zinc compound in the raw material gas is deposited on a substrate surface to form a precursor layer, and a second step of introducing a reactive gas into the processing environment so that the precursor layer reacts with the reactive gas.

Furthermore, in the manufacturing method of the present invention, the preferred reactive gas is an oxidizing gas, and the zinc-containing film is a zinc oxide film.

Furthermore, in the manufacturing method of the present invention, the preferred reactive gas is a gas containing ozone or water vapor.

Furthermore, in the manufacturing method of the present invention, the temperature at which the precursor layer reacts with the reactive gas is preferably in the range of 50°C to 200°C.

Furthermore, it is preferred that there is a step of exhausting the gas in the processing environment between the first step and the second step and in at least one of the steps after the second step. [Effect of the invention]

According to the present invention, a thin film forming raw material for the ALD method can be provided by containing a specific zinc compound, which has a low melting point, high volatility, and can react with a reactive gas at a low temperature. A method for producing a high-quality and smooth zinc-containing thin film by the ALD method with good productivity using the thin film forming raw material of the present invention can also be provided.

＜Thin film forming raw materials＞

First, the thin film forming raw material used in the ALD method of the present invention is described. The thin film forming raw material of the present invention is characterized by containing a zinc compound represented by the above general formula (1), and the zinc compound is used as a precursor when forming a thin film using the ALD method.

In the above general formula (1), ^R1 and ^R2 each independently represent an alkyl group having 1 to 5 carbon atoms, a trimethylsilyl group or a trifluoromethyl group, but ^R1 and ^R2 are different groups.

Since the zinc compound is used as a precursor for forming a thin film by the ALD method, it is preferably in liquid form at 25°C under normal pressure, and the temperature at which the weight is reduced by 50% by a reduced pressure thermogravimetric differential thermal analyzer (TG-DTA) is 100°C or less.

Here, in the general formula (1), examples of the alkyl group having 1 to 5 carbon atoms represented by ^R1 and ^R2 include methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, n-pentyl, isopentyl, sec-pentyl, t-pentyl, and the like.

In the present invention, the zinc compound in which ^R1 is a tertiary alkyl group and ^R2 is a dialkyl group is preferred because it has a low melting point, high volatility, can react with reactive gases at low temperatures, and can form a zinc-containing film with good productivity. The zinc compound in which ^R1 is a tertiary butyl group and ^R2 is an isopropyl group is preferred because its effect is more significant.

Specific examples of the zinc compound represented by the general formula (1) are the following No. 1 to No. 20, but the present invention is not limited to these compounds. In the following No. 1 to No. 20 compounds, "Me" represents "methyl", "Et" represents "ethyl", "iPr" represents "isopropyl", "tBu" represents "tert-butyl", "sBu" represents "sec-butyl", "iBu" represents "isobutyl", "tAm" represents "tert-pentyl", "SiMe ₃ " represents "trimethylsilyl", and "CF ₃ " represents "trifluoromethyl".

The method for producing the compound represented by the general formula (1) is not particularly limited, and the compound can be produced by applying a known reaction. As a production method, for example, when R ¹ is a tertiary alkyl group and R ² is a dialkyl group, a dialkylamine having such alkyl groups is dissolved in tetrahydrofuran (THF), reacted with n-butyl lithium (nBuLi), and a THF solution of a dialkyl lithium amide compound is prepared. The solution is then added dropwise to an ether solution of zinc chloride to react the dialkyl lithium amide compound with zinc chloride, the solvent is removed, hexane is added to the resulting residue, and the mixture is filtered. The solvent is removed from the filtered solution, and the mixture is purified by distillation to obtain the compound.

The thin film forming raw material used for the ALD method of the present invention only needs to contain the zinc compound represented by the above general formula (1) as a precursor to the thin film, and its composition varies according to the type of thin film to be formed. For example, when a thin film containing only zinc as a metal is produced, the thin film forming raw material of the present invention does not contain metal compounds or semi-metal compounds other than zinc. On the other hand, when a thin film containing zinc metal and metals and/or semi-metals other than zinc is produced, the thin film forming raw material of the present invention may contain compounds containing the desired metal and/or semi-metal compounds (hereinafter also referred to as "other precursors") in addition to the zinc compound represented by the general formula (1).

In the multi-component ALD method using a plurality of precursors, other precursors that can be used together with the zinc compound represented by the general formula (1) are not particularly limited, and generally known precursors used in thin film forming raw materials for the ALD method can be used.

Examples of the other precursors include compounds of one or more selected from the group consisting of compounds used as organic ligands such as alcohol compounds, diol compounds, β-diketone compounds, cyclopentadiene compounds, and organic amine compounds, and silicon or metal. In addition, examples of the metal species of the precursor include lithium, sodium, potassium, magnesium, calcium, strontium, barium, titanium, zirconium, arsenic, vanadium, niobium, chromium, molybdenum, tungsten, manganese, iron, zirconium, ruthenium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, aluminum, gallium, indium, germanium, lead, antimony, bismuth, radium, niobium, ruthenium, yttrium, yttrium, yttrium, arsenic, neodymium, bismuth, samarium, tungsten, gadolinium, aluminum, ruthenium, beryl, arsenic, or tantalum.

Examples of alcohol compounds used as organic ligands of the above-mentioned other precursors include alkanols such as methanol, ethanol, propanol, isopropanol, butanol, sec-butanol, isobutanol, t-butanol, pentanol, isopentanol, t-pentanol, etc.; 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-methoxy-1-methylethanol, 2-methoxy-1,1-dimethylethanol, 2-ethoxy-1,1-dimethylethanol, 2-isopropoxy-1,1-dimethylethanol, 2-butoxy-1,1- Ether alcohols such as dimethylethanol, 2-(2-methoxyethoxy)-1,1-dimethylethanol, 2-propoxy-1,1-diethylethanol, 2-sec-butoxy-1,1-diethylethanol, and 3-methoxy-1,1-dimethylpropanol; dialkylamino alcohols such as dimethylaminoethanol, ethylmethylaminoethanol, diethylaminoethanol, dimethylamino-2-pentanol, ethylmethylamino-2-pentanol, dimethylamino-2-methyl-2-pentanol, ethylmethylamino-2-methyl-2-pentanol, and diethylamino-2-methyl-2-pentanol.

Examples of diol compounds used as organic ligands for the above-mentioned other precursors include 1,2-ethanediol, 1,2-propylene glycol, 1,3-propylene glycol, 2,4-hexanediol, 2,2-dimethyl-1,3-propylene glycol, 2,2-diethyl-1,3-propylene glycol, 1,3-butylene glycol, 2,4-butylene glycol, 2,2-diethyl-1,3-butylene glycol, 2-ethyl-2-butyl-1,3-propylene glycol, 2,4-pentanediol, 2-methyl-1,3-propylene glycol, 2-methyl-2,4-pentanediol, 2,4-hexanediol, and 2,4-dimethyl-2,4-pentanediol.

Examples of β-diketone compounds used as organic ligands of the above-mentioned other precursors include acetylacetone, hexane-2,4-dione, 5-methylhexane-2,4-dione, heptane-2,4-dione, 2-methylheptane-3,5-dione, 5-methylheptane-2,4-dione, 6-methylheptane-2,4-dione, 2,2-dimethylheptane-3,5-dione, 2,6-dimethylheptane-3,5-dione, 2,2,6-trimethylheptane-3,5-dione, 2,2,6,6-tetramethylheptane-3,5-dione, octane-2,4-dione, 2,2,6-trimethyloctane-3,5-dione, 2,6-dimethyloctane-3,5-dione, 2,9-dimethylnonane-4,6-dione, Alkyl-substituted β-diketones such as 2-methyl-6-ethyldecane-3,5-dione and 2,2-dimethyl-6-ethyldecane-3,5-dione; fluorine-substituted β-diketones such as 1,1,1-trifluoropentane-2,4-dione, 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dione, 1,1,1,5,5,5-hexafluoropentane-2,4-dione and 1,3-diperfluorohexylpropane-1,3-dione; ether-substituted β-diketones such as 1,1,5,5-tetramethyl-1-methoxyhexane-2,4-dione, 2,2,6,6-tetramethyl-1-methoxyheptane-3,5-dione and 2,2,6,6-tetramethyl-1-(2-methoxyethoxy)heptane-3,5-dione, etc.

Examples of cyclopentadiene compounds used as the organic ligands of the above-mentioned other precursors include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, propylcyclopentadiene, isopropylcyclopentadiene, butylcyclopentadiene, sec-butylcyclopentadiene, isobutylcyclopentadiene, tert-butylcyclopentadiene, dimethylcyclopentadiene, tetramethylcyclopentadiene, pentamethylcyclopentadiene, etc. Examples of organic amine compounds used as the above-mentioned organic ligands include methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, tert-butylamine, isobutylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, ethylmethylamine, propylmethylamine, isopropylmethylamine, etc.

The above-mentioned other precursors are known in the art, and their production methods are also known. For example, when an alcohol compound is used as a ligand, the precursor can be produced by reacting the aforementioned inorganic salt of the metal or its hydrate with the alkali metal alkoxide of the alcohol compound. Here, the inorganic salt of the metal or its hydrate can be exemplified by metal halides, nitrates, etc., and the alkali metal alkoxide can be exemplified by sodium alkoxide, lithium alkoxide, potassium alkoxide, etc.

In the ALD method of the multi-component system as described above, there are a method of vaporizing and supplying thin film forming raw materials as individual components (hereinafter referred to as a "single source method") and a method of vaporizing and supplying a mixed raw material in which multiple component raw materials are mixed in advance in a desired composition (hereinafter referred to as a "mixed source method"). In the case of the single source method, the above-mentioned other precursor is preferably a compound whose thermal and/or oxidative decomposition behavior is similar to that of the zinc compound represented by the above-mentioned general formula (1). In the case of the mixed source method, the above-mentioned other precursor is preferably a compound whose thermal and/or oxidative decomposition behavior is similar to that of the zinc compound represented by the above-mentioned general formula (1), and preferably a compound that does not cause deterioration due to chemical reactions when mixed.

In the case of a mixed source method of a multi-component ALD method, a mixture of the zinc compound represented by the general formula (1) and other precursors or a mixed solution of the mixture dissolved in an organic solvent can be used as a thin film forming raw material.

The organic solvent is not particularly limited, and a well-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, 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, and methyl cyclohexanone; hexane, cyclohexane, , methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, heptane, octane, toluene, xylene and other hydrocarbons; 1-cyanopropane, 1-cyanobutane, 1-cyanohexane, cyanocyclohexane, cyanobenzene, 1,3-dicyanopropane, 1,4-dicyanobutane, 1,6-dicyanohexane, 1,4-dicyanocyclohexane, 1,4-dicyanobenzene and other hydrocarbons having cyano groups; pyridine, methylpyridine, etc. These organic solvents can be used alone or in combination of two or more depending on the solubility of the solute, the relationship between the use temperature and the boiling point, the ignition point, etc.

When the thin film forming raw material used for the ALD method of the present invention is a mixed solution with the above-mentioned organic solvent, it is preferably prepared so that the total amount of the pre-driver in the thin film forming raw material is 0.01 mol/L to 2.0 mol/L, and particularly preferably 0.05 mol/L to 1.0 mol/L.

Furthermore, the thin film forming raw material for the ALD method of the present invention may contain a nucleophilic reagent if necessary in order to improve the stability of the zinc compound represented by the above general formula (1) and other precursors. Examples of the nucleophilic reagent include glycol ethers such as glyme, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether, crown ethers such as 18-crown-6, dicyclohexyl-18-crown-6, 24-crown-8, dicyclohexyl-24-crown-8, and dibenzo-24-crown-8, ethylenediamine, N,N′-tetramethylethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, 1,1,4,7,7-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriamine, Polyamines such as ethyltetramine and triethoxytriethylamine, cyclic polyamines such as tetraazacyclotetradecane (Cyclam) and tetraazacyclododecane (cyclen), heterocyclic compounds such as pyridine, pyrrolidine, piperidine, morpholine, N-methylpyrrolidine, N-methylpiperidine, N-methylmorpholine, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, oxazole, thiazole, oxathiocyclopentane, β-ketoesters such as methyl acetylacetate, ethyl acetylacetate, 2-methoxyethyl acetylacetate, or acetylacetone, β-diketones such as 2,4-hexanedione, 2,4-heptanedione, 3,5-heptanedione, di-t-pentanoylmethane, etc. The amount of the nucleophilic reagents used is preferably in the range of 0.1 mol to 10 mol, more preferably in the range of 1 mol to 4 mol, relative to 1 mol of the total amount of the precursor.

The total amount of precursors is the total amount of the zinc compound represented by the general formula (1) and other zinc-containing precursors when the thin film forming raw material used for the ALD method of the present invention does not contain metal compounds and semi-metal compounds other than the zinc compound; when the thin film forming raw material of the present invention contains other precursors, it is the total amount of the zinc compound represented by the general formula (1) and other precursors.

The thin film forming raw materials used in the ALD method of the present invention are expected to be free of impure metal elements, impure halogens such as impure chlorine, and impure organic components other than the components that constitute them. The impure metal element content is preferably less than 100 ppb per element, and more preferably less than 10 ppb. The total amount is preferably less than 1 ppm, and more preferably less than 100 ppb. In particular, when used as a gate insulating film, gate film, or barrier film of LSI, the content of alkali metal elements and alkaline earth metal elements that affect the electrical properties of the resulting thin film must be reduced. The impure halogen content is preferably less than 100 ppm, more preferably less than 10 ppm, and even more preferably less than 1 ppm. The total amount of impurity organic components is preferably 500 ppm or less, more preferably 50 ppm or less, and even more preferably 10 ppm or less. In addition, since moisture is the cause of particle generation in the film forming raw material and particle generation during film formation, in order to reduce the moisture content of each of the precursor, organic solvent and nucleophilic reagent, it is best to remove moisture as much as possible before use. The moisture content of each of the precursor, organic solvent and nucleophilic reagent is preferably 10 ppm or less, and more preferably 1 ppm or less.

Furthermore, the thin film forming raw material used in the ALD method of the present invention preferably contains no particles in order to reduce or prevent particle contamination of the formed thin film. Specifically, in the particle measurement of the liquid phase by a light scattering liquid particle detector, the number of particles larger than 0.3 μm is preferably less than 100 in 1 ml of the liquid phase, and the number of particles larger than 0.2 μm is more preferably less than 100 in 1 ml of the liquid phase.

<Method for producing zinc-containing thin film> Next, the method for producing the zinc-containing thin film of the present invention using the above-mentioned thin film forming raw material for the ALD method is described.

The apparatus used for manufacturing a zinc-containing thin film by the ALD method of the present invention can use a well-known ALD apparatus. Specific examples of the apparatus include an apparatus that can supply a precursor by bubbling as shown in FIGS. 1 and 3, and an apparatus having a vaporization chamber as shown in FIGS. 2 and 4. Another example is an apparatus that can perform plasma treatment on a reactive gas as shown in FIGS. 3 and 4. It is not limited to a single-wafer apparatus having a film-forming chamber (hereinafter referred to as a "deposition reaction section") as shown in FIGS. 1 to 4, and an apparatus that can process multiple wafers at the same time using a batch furnace can also be used.

The method for manufacturing a zinc-containing thin film by ALD of the present invention is characterized by comprising the following steps: introducing a raw material gas for vaporizing the thin film forming raw material into a deposition reaction part (processing environment) to deposit the zinc compound in the raw material gas on the surface of the substrate to form a precursor layer (step 1); and introducing a reactive gas into the deposition reaction part (processing environment) to react the precursor layer with the reactive gas (step 2). In addition, there is a step of exhausting the gas in the deposition reaction part (processing environment) (exhaust step) in at least one of the steps between the first step and the second step and after the second step.

As one embodiment of the method for manufacturing a zinc-containing thin film of the present invention, a method for manufacturing a zinc-containing thin film is described by sequentially performing step 1, exhaust step, step 2, and exhaust step as described above, setting the deposition of the series of operations as a cycle, and repeating the cycle several times. The following describes each step in detail.

(Step 1) Step 1 includes a raw material gas introduction step of vaporizing the thin film forming raw material used in the ALD method into steam (hereinafter referred to as "raw material gas"), introducing the raw material gas into a film forming chamber provided with a substrate, and a precursor layer formation step of depositing the zinc compound in the raw material gas on the surface of the substrate provided in the deposition reaction section to form a precursor layer.

・Raw material gas introduction step As a method for transporting and supplying a thin film forming raw material used in the ALD method in the raw material gas introduction step, there are a gas transport method in which the raw material for thin film formation is vaporized into vapor by heating and/or reducing the pressure in a container storing the raw material for thin film formation (hereinafter referred to as "raw material container"), and the vapor is introduced into a deposition reaction part where a substrate is provided together with a carrier gas such as argon, nitrogen, helium, etc. as needed, as shown in FIG1 and FIG3, and a liquid transport method in which the raw material for thin film formation is transported to a vaporization chamber in a liquid or solution state, heated and/or reduced the pressure in the vaporization chamber to vaporize into vapor, and the vapor is introduced into the deposition reaction part as a raw material gas, as shown in FIG2 and FIG4. In the case of the gas transport method, the zinc compound represented by the above general formula (1) itself can be used as the raw material for thin film formation. In the case of the liquid delivery method, the zinc compound represented by the general formula (1) or a solution of the compound dissolved in an organic solvent can be used as the thin film forming raw material. The mixture or mixed solution may further contain a nucleophilic reagent or the like.

In addition to the above-mentioned gas delivery method and liquid delivery method, as a method used for the raw material gas introduction step, as a multi-component system ALD method including a plurality of precursors, there are a single source method and a mixed source method as described in the column of thin film forming raw materials, but when any of the introduction methods is used, it is preferred that the thin film forming raw materials used for the ALD method of the present invention are vaporized at 0°C to 200°C. Furthermore, when the thin film forming raw materials are vaporized into steam in the raw material container or the vaporization chamber, the pressure in the raw material container and the pressure in the vaporization chamber are preferably in the range of 1Pa to 10,000Pa.

Here, examples of the material of the substrate disposed in the deposition reaction part include silicon; ceramics such as silicon nitride, titanium nitride, tantalum nitride, titanium oxide, titanium nitride, ruthenium oxide, zirconium oxide, einsteinium oxide, and tantalum oxide; glass; metals such as metal cobalt and metal ruthenium. Examples of the shape of the substrate include plate, sphere, fiber, and scale. The surface of the substrate may be a plane or a three-dimensional structure such as a groove structure.

・Precursor layer formation step The precursor layer formation step is to deposit the zinc compound represented by the above general formula (1) in the raw material gas introduced into the deposition reaction section provided with the substrate on the substrate surface, thereby forming a precursor layer on the substrate surface. At this time, the substrate may be heated, or the deposition reaction section may be heated to apply heat. The conditions for forming the precursor layer are not particularly limited. For example, the reaction temperature (substrate temperature), reaction pressure, deposition rate, etc. may be appropriately determined according to the desired thickness of the precursor layer and the type of thin film forming raw material. With respect to the reaction temperature, it is preferably 100°C or more, which is a temperature at which the thin film forming raw material used for the ALD method of the present invention is fully reacted on the substrate surface, and more preferably 100°C to 200°C. The reaction pressure is preferably 1Pa~1,0000Pa, more preferably 10Pa~1,000Pa.

In addition, the above deposition rate can be controlled by the supply conditions of the thin film forming raw materials (evaporation temperature, evaporation pressure), reaction temperature, and reaction pressure. If the deposition rate is high, the properties of the obtained thin film may deteriorate, and if it is low, productivity may be problematic. Therefore, it is preferably 0.01 nm/min to 100 nm/min, and more preferably 1 nm/min to 50 nm/min.

Furthermore, when the thin film forming raw material contains a precursor other than the zinc compound represented by the general formula (1), the other precursor is deposited on the substrate surface together with the zinc compound.

(Exhaust step) After the above-mentioned step 1, the raw material gas containing the zinc compound that has not been deposited on the substrate surface is exhausted from the deposition reaction part. At this time, the raw material gas is ideally exhausted from the deposition reaction part completely, but it is not necessary to exhaust it completely. Examples of exhaust methods include a method of purging the inside of the deposition reaction part with an inert gas such as helium, nitrogen, argon, etc., a method of exhausting the inside of the system by depressurizing the system, and a combination of these methods. The decompression degree during decompression is preferably in the range of 0.01Pa~300Pa, and more preferably in the range of 0.01Pa~100Pa.

(Step 2) The second step is to introduce a reactive gas into the deposition reaction part after the exhaust step, and react the reactive gas with the precursor layer, i.e., the zinc compound deposited on the substrate surface, by the action of the reactive gas or the action of the reactive gas and heat. Examples of the reactive gas include oxidizing gases such as oxygen, ozone, nitrogen dioxide, nitric oxide, water vapor, hydrogen peroxide, formic acid, acetic acid, acetic anhydride, reducing gases such as hydrogen, organic amine compounds such as monoalkylamine, dialkylamine, trialkylamine, alkylenediamine, nitriding gases such as hydrazine and ammonia, etc. These reactive gases can be used alone or in combination of two or more. Among them, the thin film forming raw material used for the ALD method of the present invention has the property of reacting with an oxidizing gas at a particularly low temperature, and reacts with ozone and water vapor at a low temperature in particular. From the viewpoint of obtaining a thicker film thickness per cycle and being able to manufacture a thin film with good productivity, it is preferred to use a gas containing ozone or water vapor as the reactive gas, and it is more preferred to use a gas containing water vapor. When the reactive gas is an oxidizing gas, a zinc oxide-containing thin film is formed. Furthermore, when the reactive gas is an oxidizing gas, as a precursor in the first step, when only the zinc compound of the above general formula (1) is used, a zinc oxide thin film is formed.

When heat is used, the temperature is preferably 50°C to 200°C, more preferably 100°C to 200°C. Since the ALD window of the thin film forming raw material and reactive gas used in the ALD method of the present invention is about 100°C to 150°C, it is further preferred to react the precursor layer with the reactive gas at a temperature of 100°C to 150°C. In addition, the pressure of the deposition reaction part during this step is preferably 1Pa to 10,000Pa, more preferably 10Pa to 1,000Pa.

The thin film forming raw material used in the ALD method of the present invention has good reactivity with the above-mentioned reactive gas. By using the thin film forming raw material of the present invention, a high-quality zinc-containing thin film with a low residual carbon content can be manufactured with good productivity.

(Exhaust step) After the above-mentioned step 2, the unreacted reactive gas and byproduct gas are exhausted from the sedimentation reaction part. At this time, the reactive gas and byproduct gas are ideally exhausted from the sedimentation reaction part completely, but it is not necessary to exhaust them completely. The exhaust method and the degree of decompression are the same as those of the exhaust step performed between the above-mentioned steps 1 and 2.

As described above, the first step, the exhaust step, the second step, and the exhaust step are performed in sequence, and the deposition of the series of operations is set as a cycle. The cycle is repeated several times until a film with a required film thickness is obtained, thereby manufacturing a zinc-containing film with a desired film thickness. According to the method for manufacturing a thin film using the ALD method, the film thickness of the formed zinc-containing film can be controlled by the number of cycles mentioned above.

In addition, in the manufacturing method of the zinc-containing thin film of the present invention, as shown in FIG3 and FIG4, energy such as plasma, light, voltage, etc. can also be applied to the deposition reaction part, and a catalyst can also be used. The time of applying the energy and the time of using the catalyst are not particularly limited, for example, when the raw material gas for thin film formation raw material of the ALD method is introduced in the first step, when the precursor layer is formed, when the heating is performed, or when the reactive gas is introduced in the second step or when the reactive gas and the precursor layer are reacted, when the system is exhausted in the exhaust step, or between the above steps.

In addition, in the manufacturing method of the thin film of the present invention, after the zinc-containing thin film is formed, in order to obtain better electrical properties, an annealing treatment can also be performed in an inert environment, an oxidizing environment, or a reducing environment. When step embedding is required, a reflow step can also be provided. The temperature in this case is 200°C to 1,000°C, preferably 250°C to 500°C.

The zinc-containing thin film produced by using the thin film forming raw material for the ALD method of the present invention can be formed into a desired type of thin film such as metal, oxide ceramic, nitride ceramic, glass, etc. by appropriately selecting other precursors, reactive gases and manufacturing conditions. The thin film is known to exhibit electrical properties and optical properties, etc., and is applied to various usage patterns. For example, the thin film can be widely used in the manufacture of electrode materials for memory elements represented by DRAM elements, resistor films, diamagnetic films used for recording layers of hard disks, and catalyst materials for solid polymer fuel cells. [Example]

Hereinafter, the present invention will be described in more detail using manufacturing examples, embodiments, etc. However, the present invention is not limited to the following embodiments, etc.

[Preparation Example 1] Synthesis of Compound No. 6 In a 200 mL 3-neck flask, add 5 g (43.43 mmol) of N-isopropyl-2-methylpropane-2-amine and THF (150 mL), cool to -78°C, and then add 27.7 mL (43.47 mmol) of nBuLi (1.57 M hexane solution) dropwise over 30 minutes. After slowly warming to room temperature, stir for 18 hours to prepare a THF solution of lithium tert-butyl (isopropyl) amide. In a 500mL 4-necked flask, add 43.4g (20.7mmol) of zinc chloride (6.5% ether solution) and 30mL of THF, and under ice cooling, add the THF solution of lithium tert-butyl (isopropyl) amide prepared in the above step dropwise over 1 hour. After heating to room temperature and stirring for 18 hours, remove the solvent at a bath temperature of 64°C and reduced pressure. Add 100mL of hexane to the resulting residue, stir, and filter. Remove the solvent at a bath temperature of 64°C and reduced pressure, and distill the resulting yellow liquid at a bath temperature of 79°C and 51Pa to obtain a colorless transparent liquid (yield 3.8g, yield 63%). The analysis results of the obtained colorless transparent liquid by ¹ H-NMR and the elemental analysis results by ICP emission spectroscopy confirmed that it was the target compound, Compound No. 6. The analysis results of the obtained colorless transparent liquid by ¹ H-NMR are shown below.

(1) ¹ H-NMR (deuterated benzene) analysis results: 1.15ppm (12H, doublet), 1.18ppm (18H, singlet), 3.09ppm (2H, septet)

(2) Elemental analysis (theoretical value) Zn: 22.3% (22.25%)

The following evaluation was performed using Compound No. 6 obtained in the above-mentioned Preparation Example 1 and the following Comparative Compounds No. 1 to No. 4. In the following Comparative Compounds No. 1 to No. 4, "iPr" represents "isopropyl", "tBu" represents "tert-butyl", "sBu" represents "sec-butyl", and "iBu" represents "isobutyl".

(1) Evaluation of state and melting point The state of the compound at 25°C under normal pressure was visually observed, and the melting point of the solid compound was measured using a micro melting point measuring device. The results are shown in Table 1.

(2) Temperature (℃) at 50% mass reduction by decompression TG-DTA The TG-DTA was used to measure the mass of the test compound at 10 Torr, 50 mL/min hydrogen flow rate, 10℃/min temperature rise rate, and 30℃~600℃. The temperature (℃) at which the mass of the test compound decreased by 50% mass was evaluated as "temperature (℃) at 50% mass reduction by decompression TG-DTA". The lower the temperature (℃) at 50% mass reduction by decompression TG-DTA, the more vapor can be obtained at a lower temperature. The results are shown in Table 1.

[Example 2] Fabrication of a zinc-containing thin film Compound No. 6 was used as a thin film forming raw material, and the ALD device of FIG1 was used under the following conditions to fabricate a zinc-containing thin film on a silicon wafer. The obtained thin film was confirmed to be a zinc oxide thin film by X-ray electron spectroscopy, and no residual carbon was detected. In addition, the film thickness was measured by a scanning electron microscope, and it was a smooth film with a film thickness of about 6 nm, and the film thickness obtained per cycle was about 0.04 nm.

(ALD device conditions) Substrate: silicon wafer Reaction temperature (substrate temperature): 100°C Reactive gas: water vapor (Steps) The following series of steps (1) to (4) is set as one cycle, and the cycle is repeated 150 times. (1) The vapor (raw material gas) of the thin film forming raw material vaporized under the conditions of raw material container temperature: 50°C and raw material container internal pressure of 100Pa is introduced into the deposition reaction part, and the zinc compound is deposited on the surface of the silicon wafer at a system pressure of 100Pa for 10 seconds to form a precursor layer. (2) The raw material gas containing the undeposited zinc compound is exhausted from the system by purging with argon for 15 seconds. (3) The reactive gas is introduced into the deposition reaction section, and the precursor layer is reacted with the reactive gas at a system pressure of 100 Pa for 0.2 seconds. (4) The unreacted reactive gas and byproduct gas are exhausted from the system by purging with argon for 60 seconds.

[Comparative Example 5] Except that Compound No. 6 was replaced with Comparative Compound No. 1, a zinc-containing thin film was produced on a silicon wafer in the same manner as in Example 2, but a smooth film could not be obtained. Furthermore, residual carbon was detected in the obtained film.

[Comparative Example 6] Except that Compound No. 6 was replaced with Comparative Compound No. 2, a zinc-containing thin film was produced on a silicon wafer in the same manner as in Example 2, but a smooth film could not be obtained. Furthermore, residual carbon was detected in the obtained film.

[Comparative Example 7] Except that Compound No. 6 was replaced with Comparative Compound No. 3, a zinc-containing thin film was produced on a silicon wafer in the same manner as in Example 2, but a smooth film could not be obtained. Furthermore, residual carbon was detected in the obtained film.

[Comparative Example 8] Except for changing compound No. 6 to comparative compound No. 4, a zinc-containing thin film was produced on a silicon wafer in the same manner as in Example 2, but a smooth film could not be obtained. Moreover, residual carbon was detected in the obtained film.

From the above, it was confirmed that by using a specific zinc compound in the thin film forming raw material used in the ALD method, which has a low melting point, high volatility, and reacts with the reactive gas at a low temperature, a zinc-containing thin film such as a zinc oxide thin film can be produced with good productivity.

[FIG. 1] is a schematic diagram showing an example of an ALD device used in the method for manufacturing a zinc-containing thin film of the present invention. [FIG. 2] is a schematic diagram showing another example of an ALD device used in the method for manufacturing a zinc-containing thin film of the present invention. [FIG. 3] is a schematic diagram showing yet another example of an ALD device used in the method for manufacturing a zinc-containing thin film of the present invention. [FIG. 4] is a schematic diagram showing yet another example of an ALD device used in the method for manufacturing a zinc-containing thin film of the present invention.

Claims (8)

A thin film forming raw material for atomic layer deposition method, comprising a zinc compound represented by the following general formula (1):

(In the formula, ^R1 and ^R2 each independently represent an alkyl group having 1 to 5 carbon atoms, a trimethylsilyl group or a trifluoromethyl group, but ^R1 and ^R2 are different groups). As for the thin film forming raw material of claim 1, wherein in the above general formula (1), R ¹ is a tertiary alkyl group, and R ² is a dialkyl group. The thin film forming raw material of claim 1 or 2, wherein in the above general formula (1), R ¹ is tert-butyl and R ² is isopropyl. A method for manufacturing a zinc-containing thin film using an atomic layer deposition method, comprising a first step of introducing a raw material gas for vaporizing a thin film forming raw material as in any one of claims 1 to 3 into a processing environment, causing the zinc compound in the raw material gas to be deposited on the surface of a substrate to form a precursor layer, and a second step of introducing a reactive gas into the processing environment, causing the aforementioned precursor layer to react with the aforementioned reactive gas. The method for manufacturing a zinc-containing film as claimed in claim 4, wherein the reactive gas is an oxidizing gas and the zinc-containing film is a zinc oxide film. The method for manufacturing a zinc-containing thin film as claimed in claim 4 or 5, wherein the reactive gas is a gas containing ozone or water vapor. A method for manufacturing a zinc-containing thin film as claimed in claim 4 or 5, wherein the temperature at which the precursor layer reacts with the reactive gas is in the range of 50°C ~200°C. The method for manufacturing a zinc-containing thin film as claimed in claim 4 or 5, wherein at least one of between the first step and the second step and after the second step, there is a step of exhausting the gas in the processing environment.

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