Thin film forming material for atomic layer deposition method and thin film manufacturing method

Abstract

A raw material for formation of a thin film for use in atomic layer deposition, the raw material containing a yttrium compound represented by general formula (1). (In the formula, R1 represents a C3-8 secondary alkyl group, R2 represents C4-8 tertiary alkyl group, and R3 represents a hydrogen atom or a C1-5 primary, secondary, or tertiary alkyl group.)

Description

[Technical Field]

[0001] The present invention relates to a thin film forming material for atomic layer deposition, which contains an yttrium compound having a specific structure, and a method for producing a thin film using the same. [Background technology]

[0002] Yttrium is used as a component for forming compound semiconductors. Various raw materials have been reported as thin film forming materials for producing thin films containing yttrium atoms.

[0003] Examples of thin film manufacturing methods include sputtering, ion plating, metal organic decomposition (MOD) methods such as coating pyrolysis and sol-gel methods, chemical vapor deposition (CVD), atomic layer deposition (ALD), etc. Among these, the ALD method is the optimal thin film manufacturing process because it has many advantages, such as excellent composition controllability and step coverage, suitability for mass production, and the ability to achieve hybrid integration.

[0004] Various materials that can be used in vapor-phase thin-film formation methods such as CVD and ALD have been reported. Thin-film formation materials that can be used in the ALD method must have a temperature range called the ALD window, and this temperature range must be sufficiently wide. Therefore, it is common knowledge in the technical field that thin-film formation materials that can be used in the CVD method are often not suitable for the ALD method.

[0005] Non-Patent Document 1 discloses a CVD raw material containing tris(2,2,7-trimethyl-3,5-octanedionato)yttrium as a main component. Patent Document 1 also discloses tris(2,2,6,6-tetramethyl-3,5-heptanedionato)yttrium as an yttrium compound that can be used in the ALD method. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-355070 [Non-patent literature]

[0007] [Non-Patent Document 1] Materials Research Society Symposium Proceedings, Volume:363, Pages:195-206, 1995 Summary of the Invention [Problem to be solved by the invention]

[0008] However, Non-Patent Document 1 does not disclose any information regarding the ALD method, and does not disclose whether tris(2,2,7-trimethyl-3,5-octanedionato)yttrium is applicable to the ALD method. Furthermore, thin film forming materials for the ALD method are required to have a low melting point, excellent thermal stability, and the ability to efficiently produce high-quality thin films with low residual carbon content. However, the tris(2,2,6,6-tetramethyl-3,5-heptanedionato)yttrium disclosed in Patent Document 1 does not satisfy these requirements. Furthermore, Patent Document 1 does not disclose any specific examples of applying yttrium compounds other than tris(2,2,6,6-tetramethyl-3,5-heptanedionato)yttrium to the ALD method.

[0009] Therefore, an object of the present invention is to provide a thin film forming material for atomic layer deposition that can efficiently produce high-quality thin films that have a low melting point, excellent thermal stability, and little residual carbon, and a method for producing thin films using the same. [Means for solving the problem]

[0010] As a result of extensive investigations, the present inventors discovered that a thin film forming material for atomic layer deposition containing an yttrium compound having a specific structure can solve the above problems, and arrived at the present invention. That is, the present invention is a thin film forming material for atomic layer deposition, which contains an yttrium compound represented by the following general formula (1).

[0011] [ka]

[0012] (In the formula, R 1 represents a secondary alkyl group having 3 to 8 carbon atoms, and R 2 represents a tertiary alkyl group having 4 to 8 carbon atoms, and R 3 represents a hydrogen atom or a primary, secondary, or tertiary alkyl group having 1 to 5 carbon atoms.

[0013] The present invention also provides a method for producing a thin film containing yttrium atoms on the surface of a substrate by atomic layer deposition, the method comprising the steps of: forming a precursor thin film by adsorbing the yttrium compound in a source gas obtained by vaporizing the thin film forming source material for atomic layer deposition onto the surface of the substrate; and reacting the precursor thin film with a reactive gas to form a thin film containing yttrium atoms on the surface of the substrate. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a thin film forming material for atomic layer deposition that can produce high-quality thin films with low melting points, excellent thermal stability, and low residual carbon content with high productivity. Also, according to the present invention, it is possible to provide a method for producing high-quality thin films with low residual carbon content with high productivity by atomic layer deposition. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing an example of an atomic layer deposition apparatus used in a thin film manufacturing method according to the present invention. [Figure 2]FIG. 1 is a schematic diagram showing another example of an atomic layer deposition apparatus used in the thin film manufacturing method according to the present invention. [Figure 3] FIG. 10 is a schematic diagram showing yet another example of an atomic layer deposition apparatus used in the thin film manufacturing method according to the present invention. [Figure 4] FIG. 10 is a schematic diagram showing yet another example of an atomic layer deposition apparatus used in the thin film manufacturing method according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The thin film forming material for atomic layer deposition of the present invention contains the yttrium compound represented by the above general formula (1).

[0017] In the above general formula (1), R 1 represents a secondary alkyl group having 3 to 8 carbon atoms, and R 2 represents a tertiary alkyl group having 4 to 8 carbon atoms, and R 3 represents a hydrogen atom or a primary, secondary or tertiary alkyl group having 1 to 5 carbon atoms.

[0018] Examples of secondary alkyl groups having 3 to 8 carbon atoms include an isopropyl group, a sec-butyl group, a 1-ethylpropyl group, a 1,2-dimethylpropyl group, a sec-pentyl group, a hexan-3-yl group, a hexan-2-yl group, a heptan-3-yl group, a heptan-2-yl group, an octan-4-yl group, an octan-3-yl group, and an octan-2-yl group.

[0019] Examples of tertiary alkyl groups having 4 to 8 carbon atoms include a tertiary butyl group, a tertiary pentyl group, a 2-methylpentan-2-yl group, a 3-methylpentan-3-yl group, a 2-methylhexan-2-yl group, and a 2-methylheptan-2-yl group.

[0020] Examples of the primary, secondary, or tertiary alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a 1-ethylpropyl group, a 1,2-dimethylpropyl group, a sec-pentyl group, and a tert-pentyl group.

[0021] In the above general formula (1), R 1 In particular, those in which R is a secondary alkyl group having 5 to 8 carbon atoms are preferred because they have a low melting point, high thermal stability, and are particularly effective in forming a thin film containing yttrium with good productivity. 1 In particular, those in which is a secondary alkyl group having 7 carbon atoms are preferred because these effects are particularly high. In the above general formula (1), R 2 A tertiary alkyl group having 4 to 5 carbon atoms is preferred because of its high thermal stability. 2 is a tertiary butyl group is particularly preferred because of its particularly high thermal stability. In the above general formula (1), R 3 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, since this is highly effective in forming a thin film containing yttrium with good productivity. 3 is a hydrogen atom, which is particularly preferred since it is particularly effective in forming a thin film containing yttrium with good productivity. In the above general formula (1), R 1 and R 2 Those having a sum of the numbers of carbon atoms of 10 to 13 are preferred because they have a low melting point, high thermal stability, and are highly effective in forming a thin film containing yttrium with good productivity.

[0022] Specific examples of the yttrium compound represented by the general formula (1) above include the yttrium compounds No. 1 to No. 20 below. In the following Nos. 1 to 20, "Me" represents a methyl group, "iPr" represents an isopropyl group, "sBu" represents a secondary butyl group, "tBu" represents a tertiary butyl group, "tAm" represents a tertiary pentyl group (a group represented by the following formula (2)), "Hep" represents a heptan-3-yl group (a group represented by the following formula (3)), "Hex" represents a hexan-3-yl group (a group represented by the following formula (4)), and "Oct" represents an octan-4-yl group (a group represented by the following formula (5)).

[0023] [ka]

[0024] (In the formula, * represents a bond.)

[0025] [ka]

[0026] (In the formula, * represents a bond.)

[0027] [ka]

[0028] (In the formula, * represents a bond.)

[0029] [ka]

[0030] (In the formula, * represents a bond.)

[0031] [ka]

[0032] [ka]

[0033] [ka]

[0034] [ka]

[0035] The yttrium compound represented by the general formula (1) above is not particularly limited by its manufacturing method and can be manufactured by a well-known synthesis method. For example, it can be manufactured by reacting yttrium nitrate hexahydrate, a dione compound having a corresponding structure, and sodium hydroxide in a methanol solvent. Specifically, compound No. 3 can be manufactured by reacting yttrium nitrate hexahydrate with 2,2-dimethyl-6-ethyl-3,5-decanedione and sodium hydroxide in a methanol solvent.

[0036] The thin film forming raw material for atomic layer deposition of the present invention may contain the yttrium compound represented by the general formula (1), and the composition thereof varies depending on the type of thin film to be formed. For example, when forming a thin film containing only yttrium as the metal, the thin film forming raw material for atomic layer deposition of the present invention does not contain any metal compounds or metalloid compounds other than the yttrium compound represented by the general formula (1). On the other hand, when forming a thin film containing yttrium and a metal and / or metalloid other than yttrium, the thin film forming raw material for atomic layer deposition of the present invention may contain, in addition to the yttrium compound represented by the general formula (1), a compound containing a metal other than yttrium and / or a compound containing a metalloid (hereinafter also referred to as "other precursors"). The thin film forming raw material for atomic layer deposition of the present invention may further contain an organic solvent and / or a nucleophilic reagent, as described below.

[0037] The form of the thin film forming raw material for atomic layer deposition of the present invention is appropriately selected depending on the method of transportation and supply of the atomic layer deposition method to be used.

[0038] The transport and supply methods include a gas transport method in which the atomic layer deposition thin film forming material of the present invention is heated and / or depressurized in a container (hereinafter sometimes simply referred to as a "source container") in which it is stored to vaporize it into a source gas, and then the source gas is introduced into a deposition chamber (hereinafter sometimes referred to as a "deposition reaction section") in which a substrate is placed, along with an optional carrier gas such as argon, nitrogen, or helium; and a liquid transport method in which the atomic layer deposition thin film forming material of the present invention is transported in a liquid or solution state to a vaporization chamber, where it is vaporized by heating and / or depressurization to form a source gas, and then the source gas is introduced into the deposition chamber. In the gas transport method, the yttrium compound represented by the general formula (1) itself can be used as the atomic layer deposition thin film forming material. In the liquid transport method, the yttrium compound represented by the general formula (1) itself or a solution of the yttrium compound dissolved in an organic solvent can be used as the atomic layer deposition thin film forming material. These thin film forming materials for atomic layer deposition may further contain other precursors, nucleophilic reagents, and the like.

[0039] Furthermore, multi-component ALD methods include a method in which each component of the thin film forming material for atomic layer deposition is vaporized and supplied independently (hereinafter sometimes referred to as the "single source method"), and a method in which a mixed material in which multi-component materials are mixed in advance to a desired composition is vaporized and supplied (hereinafter sometimes referred to as the "cocktail source method"). In the cocktail source method, a mixture of the yttrium compound represented by the above general formula (1) and other precursors, or a mixed solution in which the mixture is dissolved in an organic solvent, can be used as the thin film forming material for atomic layer deposition. This mixture or mixed solution may further contain a nucleophilic reagent, etc.

[0040] The organic solvent is not particularly limited, and any well-known 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 methylcyclohexanone; hydrocarbons such as hexane, cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, heptane, octane, toluene, and xylene; hydrocarbons having a cyano group such as 1-cyanopropane, 1-cyanonobutane, 1-cyanohexane, cyanocyclohexane, cyanobenzene, 1,3-dicyanopropane, 1,4-dicyanobutane, 1,6-dicyanohexane, 1,4-dicyanocyclohexane, and 1,4-dicyanobenzene; pyridine, lutidine, and the like. These organic solvents may be used alone or in combination of two or more depending on the solubility of the solute, the relationship between the temperature used and the boiling point, the flash point, and the like.

[0041] Furthermore, in the case of a multi-component ALD method, other precursors used together with the yttrium compound represented by the above general formula (1) are not particularly limited, and well-known general precursors used as thin film formation materials for atomic layer deposition can be used.

[0042] Examples of the other precursors include compounds of silicon or a metal with one or more compounds selected from the group consisting of compounds used as organic ligands, such as alcohol compounds, glycol compounds, β-diketone compounds, cyclopentadiene compounds, and organic amine compounds. Examples of the metal species of the precursor include lithium, sodium, potassium, calcium, strontium, barium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, aluminum, gallium, indium, germanium, tin, lead, antimony, bismuth, scandium, ruthenium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

[0043] Examples of alcohol compounds that can be used as organic ligands for the other precursors include alkyl alcohols such as methanol, ethanol, propanol, isopropyl alcohol, butanol, sec-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, pentyl alcohol, isopentyl alcohol, and tert-pentyl alcohol; 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; ether alcohols such as 2-(2-methoxyethoxy)-1,1-dimethylethanol, 2-propoxy-1,1-diethylethanol, 2-s-butoxy-1,1-diethylethanol, and 3-methoxy-1,1-dimethylpropanol; and 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.

[0044] Examples of glycol compounds that can be used as organic ligands for the other precursors include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 2,4-hexanediol, 2,2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 1,3-butanediol, 2,4-butanediol, 2,2-diethyl-1,3-butanediol, 2-ethyl-2-butyl-1,3-propanediol, 2,4-pentanediol, 2-methyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 2,4-hexanediol, and 2,4-dimethyl-2,4-pentanediol.

[0045] Examples of β-diketone compounds that can be used as organic ligands for the 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, and 2-methyl-6- Examples of suitable fluorine-substituted alkyl β-diketones include ethyldecane-3,5-dione and 2,2-dimethyl-6-ethyldecane-3,5-dione; fluorine-substituted alkyl 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; and 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.

[0046] Examples of cyclopentadiene compounds that can be used as organic ligands for the other precursors include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, propylcyclopentadiene, isopropylcyclopentadiene, butylcyclopentadiene, sec-butylcyclopentadiene, isobutylcyclopentadiene, tert-butylcyclopentadiene, dimethylcyclopentadiene, and tetramethylcyclopentadiene.

[0047] Examples of organic amine compounds that can be used as organic ligands for the other precursors include methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, tert-butylamine, isobutylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, ethylmethylamine, propylmethylamine, and isopropylmethylamine.

[0048] 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 the organic ligand, the precursor can be produced by reacting the inorganic salt of the metal or a hydrate thereof described above with an alkali metal alkoxide of the alcohol compound. Examples of the inorganic salt of the metal or a hydrate thereof include metal halides and nitrates, and examples of the alkali metal alkoxide include sodium alkoxide, lithium alkoxide, and potassium alkoxide.

[0049] In the case of the single-source method, the other precursor is preferably a compound whose thermal and / or oxidative decomposition behavior is similar to that of the yttrium compound represented by the general formula (1).In the case of the cocktail-source method, the other precursor is preferably a compound whose thermal and / or oxidative decomposition behavior is similar to that of the yttrium compound represented by the general formula (1) and which does not undergo deterioration due to chemical reactions or the like when mixed.

[0050] Furthermore, the thin film forming material for atomic layer deposition of the present invention may contain a nucleophilic reagent, if necessary, to improve the stability of the yttrium compound represented by the general formula (1) and other precursors. Examples of the nucleophilic reagent include ethylene glycol ethers such as glyme, diglyme, triglyme, and tetraglyme; 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-hexamethyltriethylenetetramine; and triethylenetetramine. Examples of suitable nucleophilic reagents include polyamines such as ethoxytriethyleneamine, cyclic polyamines such as cyclam and cyclen, heterocyclic compounds such as pyridine, pyrrolidine, piperidine, morpholine, N-methylpyrrolidine, N-methylpiperidine, N-methylmorpholine, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, oxazole, thiazole, and oxathiolane, β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, and 2-methoxyethyl acetoacetate, and β-diketones such as acetylacetone, 2,4-hexanedione, 2,4-heptanedione, 3,5-heptanedione, and dipivaloylmethane. The amount of these nucleophilic reagents used is preferably 0.1 mol to 10 mol, and more preferably 1 mol to 4 mol, per mol of the total amount of precursor.

[0051] The thin film forming material for atomic layer deposition of the present invention is intended to contain as little impurity metal elements, impurity halogens such as impurity chlorine, and impurity organic components as possible, other than the components that constitute the material. The impurity metal element content is preferably 100 ppb or less per element, more preferably 10 ppb or less, and the total content is preferably 1 ppm or less, more preferably 100 ppb or less. In particular, when used as a gate insulating film, gate film, or barrier layer for an LSI, it is necessary to reduce the content of alkali metal elements and alkaline earth metal elements, which affect the electrical properties of the resulting thin film. The impurity halogen content is preferably 100 ppm or less, more preferably 10 ppm or less, and most preferably 1 ppm or less. The total content of impurity organic components is preferably 500 ppm or less, more preferably 50 ppm or less, and most preferably 10 ppm or less. Furthermore, moisture can cause particle generation in the thin film forming materials for atomic layer deposition and during thin film formation, so it is advisable to remove as much moisture as possible from the precursor, organic solvent, and nucleophilic reagent before use in order to reduce the moisture content of each. 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.

[0052] Furthermore, the thin film forming material for atomic layer deposition of the present invention preferably contains as few particles as possible to reduce or prevent particle contamination of the thin film to be formed. Specifically, in particle measurement in the liquid phase using a light scattering liquid-borne particle detector, the number of particles larger than 0.3 μm per mL of liquid phase is preferably 100 or less, the number of particles larger than 0.2 μm per mL of liquid phase is more preferably 1,000 or less, and the number of particles larger than 0.2 μm per mL of liquid phase is most preferably 100 or less.

[0053] The thin film manufacturing method of the present invention is a method for manufacturing a thin film containing yttrium atoms on the surface of a substrate by atomic layer deposition, and includes the steps of: forming a precursor thin film by adsorbing (depositing) an yttrium compound in a source gas obtained by vaporizing the thin film forming raw material for atomic layer deposition onto the surface of the substrate; and reacting the precursor thin film with a reactive gas to form a thin film containing yttrium atoms on the surface of the substrate.

[0054] Examples of materials for the substrate include silicon; ceramics such as silicon nitride, titanium nitride, tantalum nitride, titanium oxide, ruthenium oxide, zirconium oxide, hafnium oxide, and lanthanum oxide; glass; metals such as metallic cobalt, metallic iron, metallic manganese, metallic nickel, and metallic copper; and alloys such as stainless steel, brass, cupronickel, bronze, duralumin, nichrome, stellite, solder, amalgam, and carbon steel. The substrate may have a plate-like, spherical, fibrous, or flake-like shape. The substrate surface may be flat or have a three-dimensional structure such as a trench structure.

[0055] Furthermore, examples of a method for introducing the source gas obtained by vaporizing the above-mentioned thin film forming raw material for atomic layer deposition into a film formation chamber in which a substrate is placed include the gas transport method, liquid transport method, single source method, cocktail source method, etc.

[0056] Examples of the reactive gas include oxidizing gases such as oxygen, ozone, nitrogen dioxide, nitric oxide, water vapor, hydrogen peroxide, formic acid, acetic acid, and acetic anhydride; reducing gases such as hydrogen; organic amine compounds such as monoalkylamines, dialkylamines, trialkylamines, and alkylenediamines; and nitriding gases such as hydrazine and ammonia. These reactive gases may be used alone or in combination of two or more. Among these, the thin film forming material for atomic layer deposition of the present invention has the property of reacting specifically with oxidizing gases at low temperatures, particularly with ozone and water vapor. In terms of achieving a thick film thickness per cycle and enabling efficient production of thin films, it is preferable to use an oxidizing gas containing ozone, oxygen, or water vapor as the reactive gas, and it is more preferable to use an oxidizing gas containing ozone.

[0057] The manufacturing conditions further include the temperature and pressure when the atomic layer deposition thin film forming raw material is vaporized to form a raw material gas. The step of vaporizing the atomic layer deposition thin film forming raw material to form a raw material gas may be performed in a raw material container or in a vaporization chamber. In either case, the atomic layer deposition thin film forming raw material of the present invention is preferably vaporized at 0°C to 300°C. Furthermore, when the atomic layer deposition thin film forming raw material is vaporized in a raw material container or a vaporization chamber to form a raw material gas, the pressure in both the raw material container and the vaporization chamber is preferably 1 Pa to 10,000 Pa.

[0058] Furthermore, the manufacturing conditions for the thin film manufacturing method of the present invention are not particularly limited, but for example, the reaction temperature (substrate temperature), reaction pressure, deposition rate, etc. can be appropriately determined depending on the desired thickness and type of thin film. The reaction temperature is preferably 100°C or higher, at which the thin film forming raw material for atomic layer deposition of the present invention reacts sufficiently, more preferably 150°C to 400°C, and is used within the ALD window suited to the reactive gas. The film thickness is controlled by the number of cycles so as to obtain the desired film thickness.

[0059] Each step of the ALD method will be described in detail below, taking the formation of an yttrium oxide thin film as an example. First, a source gas obtained by vaporizing a thin film-forming source for atomic layer deposition is introduced into a film-forming chamber (source introduction step). The temperature and pressure for vaporizing the thin film-forming source for atomic layer deposition are preferably within the ranges of 0°C to 300°C and 1 Pa to 10,000 Pa. Next, the source gas introduced into the film-forming chamber is adsorbed (deposited) on the surface of the substrate to form a precursor thin film (precursor thin film formation step). At this time, heat may be applied by heating the substrate or the film-forming chamber. The substrate temperature during this step is preferably room temperature to 500°C, more preferably 150°C to 400°C. The ALD window when the thin film-forming source for atomic layer deposition of the present invention and an oxidizing gas are used in combination is generally within the range of 200°C to 400°C. The pressure in the system (inside the film formation chamber) during this step is preferably 1 Pa to 10,000 Pa, and more preferably 10 Pa to 1,000 Pa.

[0060] Next, unreacted source gases and by-product gases are exhausted from the film formation chamber (exhaust process). Ideally, unreacted source gases and by-product gases are completely exhausted from the film formation chamber, but complete exhaust is not necessarily required. Exhaust methods include purging the system with an inert gas such as nitrogen, helium, or argon, exhausting by reducing the pressure inside the system, and a combination of these. When reducing the pressure, the degree of pressure reduction is preferably 0.01 Pa to 300 Pa, and more preferably 0.01 Pa to 100 Pa.

[0061] Next, an oxidizing gas is introduced into the deposition chamber as a reactive gas, and an yttrium oxide thin film is formed from the precursor thin film formed in the previous precursor thin film formation step by the action of the oxidizing gas or the action of the oxidizing gas and heat (yttrium oxide thin film formation step). The temperature when heat is applied in this step is preferably room temperature to 500°C, more preferably 150°C to 400°C. Since the ALD window when the atomic layer deposition thin film forming material of the present invention is used in combination with an oxidizing gas is generally in the range of 200°C to 400°C, it is most preferable to react the precursor thin film with the oxidizing gas in the range of 200°C to 400°C. The pressure of the system (inside the deposition chamber) during this step is preferably 1 Pa to 10,000 Pa, more preferably 10 Pa to 1,000 Pa. The thin film forming material for atomic layer deposition of the present invention has good reactivity with oxidizing gas, and can efficiently produce high-quality yttrium oxide thin films with low residual carbon content.

[0062] In the thin film manufacturing method of the present invention, one cycle is a thin film deposition process performed by a series of operations consisting of the raw material introduction process, precursor thin film formation process, evacuation process, and yttrium oxide thin film formation process, and this cycle may be repeated multiple times until a thin film of the required thickness is obtained. In this case, after one cycle, it is preferable to evacuate unreacted reactive gas (oxidizing gas when forming an yttrium oxide thin film) and by-product gas from the film formation chamber in the same manner as in the evacuation process, and then perform the next cycle.

[0063] In the thin film manufacturing method of the present invention, energy such as plasma, light, or voltage may be applied, or a catalyst may be used. The timing of applying the energy and using the catalyst are not particularly limited, and may be, for example, when introducing the raw material gas in the raw material introduction step, when heating in the precursor thin film formation step or the yttrium oxide thin film formation step, when evacuating the system in the evacuation step, when introducing the oxidizing gas in the yttrium oxide thin film formation step, or between the steps.

[0064] In the method for producing a thin film of the present invention, after forming the thin film, annealing may be performed in an inert atmosphere, an oxidizing atmosphere, or a reducing atmosphere to obtain better electrical properties, and a reflow step may be performed if step filling is required. In this case, the temperature is 200°C to 1,500°C, and preferably 500°C to 1,000°C.

[0065] As an apparatus for producing a thin film using the thin film forming material for atomic layer deposition of the present invention, well-known atomic layer deposition apparatuses can be used. Specific examples of such apparatuses include an apparatus capable of supplying a precursor by bubbling, as shown in FIG. 1, and an apparatus having a vaporization chamber, as shown in FIG. 2. Also included are apparatuses capable of performing plasma treatment on a reactive gas, as shown in FIGS. 3 and 4. The apparatus is not limited to the single-wafer apparatuses shown in FIGS. 1 to 4, but can also be an apparatus capable of simultaneously processing multiple wafers using a batch furnace.

[0066] Thin films produced using the thin film-forming material for atomic layer deposition of the present invention can be formed into desired types of thin films, such as metals, oxide ceramics, nitride ceramics, and glasses, by appropriately selecting other precursors, reactive gases, and production conditions. These thin films are known to exhibit electrical and optical properties and are used in a variety of applications. For example, these thin films are widely used in the production of electrode materials for memory elements, such as DRAM elements, resistive films, diamagnetic films used in the recording layers of hard disks, and catalyst materials for polymer electrolyte fuel cells. [Example]

[0067] The present invention will be described in more detail below with reference to examples, evaluation examples and comparative examples, but the present invention is not limited to the following examples. [Example 1] Synthesis of Compound No. 3 A 1 L four-neck flask was charged with 50 g (0.131 mol) of yttrium nitrate hexahydrate and 200 mL of methanol and stirred at room temperature. A solution prepared by mixing 89.6 g (0.392 mol) of 2,2-dimethyl-6-ethyl-3,5-decanedione, 15.67 g (0.392 mol) of sodium hydroxide, and 300 mL of methanol was added dropwise at room temperature. After stirring for 19 hours at room temperature, the solvent was removed from the resulting suspension, 500 mL of dehydrated toluene was added, and the mixture was dehydrated at 125 °C using a Dean-Stark apparatus. The solvent was removed from the resulting solution, and 500 mL of dehydrated hexane was added. The mixture was heated and stirred at 60 °C for 1 hour and then filtered. The solvent was removed from the resulting filtrate, and the resulting yttrium complex was distilled at a bath temperature of 210 °C and a pressure of 44 Pa to obtain Compound No. 3 as a yellow, transparent, viscous liquid (yield: 82.03 g, 82.1%).

[0068] (Analysis value) (1) Normal Pressure TG-DTA 50% mass reduction temperature: 305°C (760 Torr, Ar flow rate: 100 mL / min, heating rate: 10°C / min, sample weight: 9.860 mg) (2) Decompression TG-DTA 50% mass reduction temperature: 215°C (10 Torr, Ar flow rate: 50 mL / min, heating rate: 10°C / min, sample weight: 9.716 mg) (3) 1 H-NMR (heavy benzene) 0.91-0.97ppm(6H,multiplet), 1.18ppm(9H,singlet), 1.26-1.48ppm(6H,multiplet), 1.71-1.78ppm(2H,multiplet), 2.07-2.14ppm(1H,multiplet), 5.76ppm(1H,singlet) (4) Elemental analysis (metal analysis: ICP-AES) Yttrium content: 11.6% by mass (theoretical value: 11.6% by mass)

[0069] [Evaluation example] The following evaluations were carried out on Compound No. 3 obtained in Example 1 and the following Comparative Compound 1. In the following Comparative Compound 1, "tBu" represents a tertiary butyl group. (1) Melting point evaluation The state of the compounds at 20° C. was observed visually. For those that were solid at 20° C., the melting points were measured using a micro melting point measuring device. The results are shown in Table 1. (2) Thermal stability evaluation The thermal decomposition onset temperature was measured using a DSC measurement device. Materials with a high thermal decomposition onset temperature are less likely to undergo thermal decomposition and can be judged to be preferable as thin film formation raw materials for atomic layer deposition. The results are shown in Table 1.

[0070] [ka]

[0071] [Table 1]

[0072] The results in Table 1 show that Compound No. 3 has a melting point 150°C or more lower than Comparative Compound 1. Compound No. 3 also has higher thermal stability than Comparative Compound 1. Compound No. 3 is significantly more suitable as a thin film formation material for atomic layer deposition than Comparative Compound 1, which has a similar structure.

[0073] [Example 2] Production of yttrium oxide thin film Using Compound No. 3 as a thin film forming source for atomic layer deposition (ALD), a yttrium oxide thin film was fabricated on a silicon wafer by the ALD method under the following conditions using the apparatus shown in Figure 1. The composition of the resulting thin film was confirmed by X-ray photoelectron spectroscopy, which revealed that the resulting thin film was yttrium oxide with a residual carbon content of less than 1.0 atom%. Furthermore, the film thickness was measured by X-ray reflectivity and averaged to find that the average film thickness was 15.0 nm, and the average film thickness obtained per cycle was 0.05 nm.

[0074] (conditions) Substrate: silicon wafer, reaction temperature (silicon wafer temperature): 300°C, reactive gas: ozone A series of steps (1) to (4) below was defined as one cycle, and 300 cycles were repeated. (1) The raw material gas vaporized under the conditions of raw material container temperature: 200°C, raw material container internal pressure: 100 Pa is introduced into the film formation chamber, and deposition is performed for 10 seconds at a system pressure: 100 Pa. (2) An argon purge is performed for 15 seconds to remove any undeposited source gas. (3) The reactive gas is introduced into the film-forming chamber and reacted at a system pressure of 100 Pa for 10 seconds. (4) Unreacted reactive gases and by-product gases are removed by argon purging for 15 seconds.

[0075] [Comparative Example 1] Production of yttrium oxide thin film An yttrium oxide thin film was produced under the same conditions as in Example 2, except that Comparative Compound 1 was used as the thin film forming raw material for atomic layer deposition. The composition of the obtained thin film was confirmed by X-ray photoelectron spectroscopy, and it was found to be yttrium oxide with a residual carbon content of 3.0 atom%. Furthermore, the film thickness was measured by X-ray reflectivity, and the average value was calculated. The average film thickness was 9.0 nm, and the average film thickness obtained per cycle was 0.03 nm.

[0076] The results of Example 2 and Comparative Example 1 show that in Example 2, the film thickness obtained per cycle is 1.6 times or more that of Comparative Example 1, and a high-quality yttrium oxide thin film with a small amount of residual carbon can be obtained with good productivity. From the above, it can be said that the present invention makes it possible to produce a high-quality yttrium oxide thin film with good productivity.

Claims

1. A thin film forming material for atomic layer deposition, comprising an yttrium compound represented by the following general formula (1): 【Chemical Formula 1】 (In the formula, R 1 represents a secondary alkyl group having 3 to 8 carbon atoms, and R 2 represents a tertiary alkyl group having 4 to 8 carbon atoms, and R 3 represents a hydrogen atom or a primary, secondary, or tertiary alkyl group having 1 to 5 carbon atoms.

2. R 1 and R 2 2. The thin film forming material for atomic layer deposition according to claim 1, wherein the sum of the numbers of carbon atoms in the above is 10 to 13.

3. A method for producing a thin film containing yttrium atoms on a surface of a substrate by atomic layer deposition, comprising: a step of adsorbing the yttrium compound in a source gas obtained by vaporizing the thin film forming source material for atomic layer deposition according to claim 1 or 2 onto the surface of the substrate to form a precursor thin film; reacting the precursor thin film with a reactive gas to form a thin film containing yttrium atoms on the surface of the substrate; A method for producing a thin film comprising the steps of:

4. The method for producing a thin film according to claim 3 , wherein the reactive gas is an oxidizing gas.

5. 5. The method for producing a thin film according to claim 4, wherein the oxidizing gas is a gas containing ozone, oxygen, or water vapor.

6. The method for producing a thin film according to any one of claims 3 to 5, wherein the precursor thin film is reacted with the reactive gas at a temperature in the range of 200°C to 400°C.

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