Raw material for forming thin film by atomic layer deposition method, and method for manufacturing thin film

Abstract

A thin film forming raw material for atomic layer deposition contains a yttrium compound represented by the following general formula (1), (where R1 represents a secondary alkyl group having 3 to 8 carbon atoms, R2 represents a tertiary alkyl group having 4 to 8 carbon atoms, and R3 represents a hydrogen atom or a primary, secondary, or tertiary alkyl group having 1 to 5 carbon atoms).

Description

Technical Field

[0001] This invention relates to a thin film forming raw material for atomic layer deposition containing a yttrium compound having a specific structure, and a method for manufacturing a thin film using the same. Prior Technology

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

[0003] Examples of thin film manufacturing methods include sputtering, ion plating, coating thermal decomposition, sol-gel methods, metal-organic decomposition (MOD), chemical vapor deposition (CVD), and atomic layer deposition (ALD). Among these, ALD is the most suitable manufacturing process for thin films due to its excellent composition control and step coverage, suitability for mass production, and ability to be integrated.

[0004] While various materials have been reported for use in vapor phase thin film formation methods such as CVD and ALD, the raw materials suitable for ALD must possess a temperature range known as the ALD window, which must be sufficiently wide. Therefore, it is common knowledge in this field that most raw materials usable in CVD are not suitable for ALD.

[0005] Non-Patent Document 1 discloses a raw material for CVD with tris(2,2,7-trimethyl-3,5-octanedioic acid)yttrium as the main component. Furthermore, Patent Document 1 discloses tris(2,2,6,6-tetramethyl-3,5-heptaneedioic acid)yttrium as a yttrium compound usable in the ALD method. [Previous Technical Documents] [Patent Literature]

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

[0007] Non-patent literature 1: Materials Research Society Symposium Proceedings, Volume: 363, Pages: 195-206, 1995 Summary of the Invention

[0008] [The problem the invention aims to solve]

[0009] However, Non-Patent Document 1 does not describe the ALD process, nor does it specify whether tris(2,2,7-trimethyl-3,5-octanedioic acid)yttrium is suitable for the ALD process. Furthermore, the film-forming raw materials used in the ALD process are required to produce high-quality films with good manufacturability, low melting points, excellent thermal stability, and low residual carbon content. However, the tris(2,2,6,6-tetramethyl-3,5-heptaneedioic acid)yttrium described in Patent Document 1 does not meet these requirements. Moreover, Patent Document 1 makes no specific examples of yttrium compounds other than tris(2,2,6,6-tetramethyl-3,5-heptaneedioic acid)yttrium being suitable for the ALD process.

[0010] Therefore, the object of the present invention is to provide a thin film forming raw material for atomic layer deposition method that can produce high-quality thin films with low melting point, excellent thermal stability and low residual carbon content, and a method for manufacturing thin films using the same. [Methods used to solve problems]

[0011] Through repeated and active review, the inventors discovered that a thin film forming material containing a yttrium compound with a specific structure for atomic layer deposition can solve the above-mentioned problems, and thus completed the present invention. That is, the present invention provides a thin film forming raw material for atomic layer deposition, which contains a yttrium compound represented by the following general formula (1).

[0012]

[0013] (In the formula, R1 represents a secondary alkyl group with 3 to 8 carbon atoms, R2 represents a tertiary alkyl group with 4 to 8 carbon atoms, and R3 represents a hydrogen atom or a primary, secondary, or tertiary alkyl group with 1 to 5 carbon atoms).

[0014] Furthermore, the present invention provides a method for fabricating a thin film containing yttrium atoms on the surface of a substrate by atomic layer deposition, and includes the steps of vaporizing the raw material for thin film formation in the above-mentioned atomic layer deposition method to adsorb the aforementioned yttrium compound in the resulting raw material gas onto the surface of the aforementioned substrate to form a precursor thin film, and the steps of reacting the precursor thin film with a reactive gas to form a thin film containing yttrium atoms on the surface of the substrate. [Invention Effects]

[0015] According to the present invention, a thin film forming raw material for atomic layer deposition (ALD) can be provided for producing high-quality thin films with low melting point, excellent thermal stability, and low residual carbon content with good manufacturability. Furthermore, according to the present invention, a method for producing high-quality thin films with low residual carbon content by ALD with good manufacturability can be provided. Simple Explanation of the Diagram

[0016] [Figure 1] is a schematic diagram showing an example of an atomic layer deposition apparatus used in the thin film manufacturing method of the present invention. [Figure 2] is a schematic diagram showing another example of an atomic layer deposition apparatus used in the thin film manufacturing method of the present invention. [Figure 3] is a schematic diagram showing another example of an atomic layer deposition apparatus used in the thin film manufacturing method of the present invention. [Figure 4] is a schematic diagram showing another example of an atomic layer deposition apparatus used in the thin film manufacturing method of the present invention. Implementation

[0017] The atomic layer deposition method of the present invention uses thin film forming raw materials containing yttrium compounds represented by the above general formula (1).

[0018] In the above general formula (1), R1 represents a secondary alkyl group with 3 to 8 carbon atoms, R2 represents a tertiary alkyl group with 4 to 8 carbon atoms, and R3 represents a hydrogen atom or a primary, secondary or tertiary alkyl group with 1 to 5 carbon atoms.

[0019] Examples of secondary alkyl groups having 3 to 8 carbon atoms include isopropyl, dibutyl, 1-ethylpropyl, 1,2-dimethylpropyl, dipentyl, hex-3-yl, hex-2-yl, hept-3-yl, hept-2-yl, oct-4-yl, oct-3-yl, and oct-2-yl.

[0020] Examples of tertiary alkyl groups with 4 to 8 carbon atoms include tert-butyl, tert-pentyl, 2-methylpent-2-yl, 3-methylpent-3-yl, 2-methylhex-2-yl, and 2-methylhept-2-yl.

[0021] Examples of alkyl groups with 1 to 5 carbon atoms include primary, secondary, or tertiary alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, dibutyl, tert-butyl, pentyl, 1-ethylpropyl, 1,2-dimethylpropyl, dipentyl, and tert-pentyl.

[0022] In the above general formula (1), R1 is a secondary alkyl group with 5 to 8 carbon atoms, which is particularly good at forming thin films with low melting point, high thermal stability and good manufacturability. Among them, R1 is a secondary alkyl group with 7 carbon atoms, which is particularly good at these effects. In the above general formula (1), R2 is a tertiary alkyl group with 4 to 5 carbon atoms, which is better due to its high thermal stability. Among them, R2 is a tertiary butyl group, which is particularly good due to its exceptionally high thermal stability. In the above general formula (1), R3 is a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, which is better because it has a high productivity in forming yttrium-containing films. Among them, R3 being a hydrogen atom is particularly better because it has a particularly high productivity in forming yttrium-containing films. In the above general formula (1), the sum of the number of carbon atoms of R1 and R2 is 10 to 13, which is better because it has a high degree of manufacturability and can form thin films with low melting point, high thermal stability and high yttrium content.

[0023] As a specific example of a yttrium compound represented by the above general formula (1), the yttrium compounds No. 1 to No. 20 below are examples. In No. 1 to No. 20 below, "Me" represents methyl, "iPr" represents isopropyl, "sBu" represents dibutyl, "tBu" represents terbutyl, "tAm" represents terpentyl (the group represented by formula (2) below), "Hep" represents hept-3-yl (the group represented by formula (3) below), "Hex" represents hex-3-yl (the group represented by formula (4) below), and "Oct" represents oct-4-yl (the group represented by formula (5) below).

[0024]

[0025] (In the formula, ✽ represents a bond).

[0026]

[0027] (In the formula, ✽ represents a bond).

[0028]

[0029] (In the formula, ✽ represents a bond).

[0030]

[0031] (In the formula, ✽ represents a bond).

[0032]

[0033]

[0034]

[0035]

[0036] The method of manufacturing yttrium compounds represented by the above general formula (1) is not particularly limited and can be manufactured by well-known synthetic methods. For example, they can be manufactured by reacting yttrium hexahydrate and a corresponding diketone compound with sodium hydroxide in methanol solvent. Specifically, compound No. 3 can be manufactured by reacting yttrium hexahydrate with 2,2-dimethyl-6-ethyl-3,5-decanedione and sodium hydroxide in methanol solvent.

[0037] The atomic layer deposition method of the present invention uses thin film forming raw materials that only contain yttrium compounds represented by the above general formula (1), and their composition varies depending on the type of thin film. For example, when manufacturing a thin film containing only yttrium as a metal, the thin film forming raw materials of the atomic layer deposition method of the present invention do not contain metal compounds or half-metal compounds other than the yttrium compounds represented by the above general formula (1). On the other hand, when manufacturing a thin film containing yttrium and metals and / or half-metals other than yttrium, the thin film forming raw materials of the atomic layer deposition method of the present invention, in addition to containing yttrium compounds represented by the above general formula (1), may also contain compounds containing metals other than yttrium and / or compounds containing half-metals (hereinafter also referred to as other precursors). The thin film forming raw materials of the atomic layer deposition method of the present invention, as described later, may further contain organic solvents and / or nucleophilic reagents.

[0038] The form of the raw material used in the atomic layer deposition method of the present invention for thin film formation is appropriately selected based on the delivery and supply methods of the atomic layer deposition method.

[0039] As for the above-mentioned delivery method, there are the following methods: a gas delivery method in which the raw material for thin film formation by atomic layer deposition of the present invention is vaporized by heating and / or depressurizing in a container (hereinafter sometimes referred to as "raw material container"), and the raw material gas is introduced together with a carrier gas such as argon, nitrogen, or helium as needed into a film-forming chamber (hereinafter sometimes referred to as "deposition reaction section") in which a substrate is provided; and a liquid delivery method in which the raw material for thin film formation by atomic layer deposition of the present invention is delivered in a liquid or solution state to a vaporization chamber, vaporized by heating and / or depressurizing in the vaporization chamber to form a raw material gas, and the raw material gas is introduced into the film-forming chamber. In the gas delivery method, the yttrium compound represented by the above general formula (1) can itself be used as a raw material for thin film formation by atomic layer deposition. In the liquid delivery method, the yttrium compound represented by the above general formula (1) or a solution of the yttrium compound dissolved in an organic solvent can be used as a raw material for thin film formation by atomic layer deposition. The raw materials used in these atomic layer deposition methods to form thin films may also contain other precursors, nucleophiles, etc.

[0040] Furthermore, in multi-component ALD methods, there are methods where the raw materials for thin film formation in atomic layer deposition are vaporized and supplied independently for each component (hereinafter also referred to as the "single-source method"), and methods where multi-component raw materials are vaporized and supplied in advance as a mixture of raw materials with a desired composition (hereinafter also referred to as the "mixed-source method"). In the mixed-source method, a mixture of yttrium compounds represented by the above general formula (1) and other precursors, or a mixed solution of the mixture dissolved in an organic solvent, can be used as the raw material for thin film formation in atomic layer deposition. The mixture or mixed solution may further contain nucleophilic reagents, etc.

[0041] As for the aforementioned organic solvents, well-known general organic solvents are used with particular restriction. Examples of such organic solvents 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 pentyl ketone, cyclohexanone, and methyl cyclohexanone; and hexane and cyclohexane. Hydrocarbons such as methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, heptane, octane, toluene, and xylene; hydrocarbons containing cyano groups such as 1-cyanopropane, 1-cyanobutane, 1-cyanohexane, cyanocyclohexane, cyanobenzene, 1,3-dicyanopropane, 1,4-dicyanobutane, 1,6-dicyanohexane, 1,4-dicyanocyclohexane, and 1,4-dicyanobenzene; and pyridine, dimethylpyridine, etc. These organic solvents can be used alone or in mixtures of two or more, depending on the solubility of the solute, the relationship between the operating temperature and the boiling point and ignition point.

[0042] Furthermore, in the multi-component ALD method, there are no particular restrictions on other precursors used in conjunction with the yttrium compound represented by the above general formula (1), and conventional precursors used in thin film formation by atomic layer deposition can be used.

[0043] Examples of other precursors include compounds of silicon or metals, such as one or more compounds selected from the group consisting of alcohols, diols, β-diketones, cyclopentadienes, and organic amines that function as organic ligands. Examples of metals that can be used as precursors 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, tungsten, neodymium, beryllium, samarium, europium, thorium, tungsten, dysprosium, holmium, erbium, thionium, ytterbium, or ruthenium.

[0044] Examples of alcohol compounds used as organic ligands for the aforementioned other precursors include, for example, alkanoates such as methanol, ethanol, propanol, isopropanol, butanol, dibutanol, isobutanol, terbutanol, pentanol, isopentanol, and terpentanol; 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, and 2-butoxy-1,1- Ether alcohols such as dimethylethanol, 2-(2-methoxyethoxy)-1,1-dimethylethanol, 2-propoxy-1,1-diethylethanol, 2-dibutoxy-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, methylethylamino-2-methyl-2-pentanol, and diethylamino-2-methyl-2-pentanol.

[0045] Examples of diol compounds used as organic ligands for the aforementioned other precursors include, for example, 1,2-ethylene glycol, 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, 2,4-dimethyl-2,4-pentanediol, etc.

[0046] Examples of β-diketone compounds used as organic ligands for the aforementioned other precursors include, for example, acetoacetone, 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, and 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; fluorinated 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.

[0047] Examples of cyclopentadiene compounds used as organic ligands for the aforementioned other precursors include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, propylcyclopentadiene, isopropylcyclopentadiene, butylcyclopentadiene, dibutylcyclopentadiene, isobutylcyclopentadiene, tributylcyclopentadiene, dimethylcyclopentadiene, tetramethylcyclopentadiene, etc.

[0048] Examples of organic amine compounds used as organic ligands for the aforementioned other precursors include methylamine, ethylamine, propylamine, isopropylamine, butylamine, dibutylamine, terbutylamine, isobutylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, ethylmethylamine, propylmethylamine, isopropylmethylamine, etc.

[0049] The aforementioned precursors are known in the art, and their manufacturing methods are also known. For example, when using an alcohol compound as an organic ligand, the precursor can be produced by reacting the aforementioned inorganic salt of a metal or its hydrate with an alkali metal alkoxide of its alcohol compound. Examples of inorganic salts or their hydrates that are metals include metal halides and nitrates, while examples of alkali metal alkoxides include sodium alkoxides, lithium alkoxides, and potassium alkoxides.

[0050] In the single-source method, the other precursors mentioned above are preferably compounds whose thermal and / or oxidative decomposition behavior is similar to that of the yttrium compound represented by the general formula (1) above. In the mixed-source method, the other precursors mentioned above are preferably compounds that do not deteriorate due to chemical reactions or the like when mixed, except that their thermal and / or oxidative decomposition behavior is similar to that of the yttrium compound represented by the general formula (1) above.

[0051] Furthermore, the thin film forming raw materials used in the atomic layer deposition method of the present invention may, as needed, contain nucleophilic reagents to improve the stability of the yttrium compounds and other precursors represented by the above general formula (1). Examples of nucleophilic reagents include, for example, ethylene glycol ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, etc.; crown ethers such as 1,8-crown ether-6, dicyclohexyl-18-crown ether-6, 24-crown ether-8, dicyclohexyl-24-crown ether-8, dibenzo-24-crown ether-8, etc.; ethylenediamine, N,N'-tetramethylethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, 1,1,4,7,7-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetramine Polyamines such as amines 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, and oxothiocyclopentane; β-keto esters such as methyl acetate, ethyl acetate, and 2-methoxyethyl acetate; or β-diketones such as acetoacetone, 2,4-hexanedione, 2,4-heptanedione, 3,5-heptanedione, and dipentacyclomethane. The amount of these nucleophilic reagents used is preferably in the range of 0.1 mol to 10 mol, and more preferably in the range of 1 mol to 4 mol, relative to the total amount of the precursor.

[0052] The atomic layer deposition (ALD) method of this invention aims to minimize the presence of impurities in the thin film forming raw materials, such as impurity metal elements, impurity halogens (e.g., chlorine), and impurity organic components. 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 using it as a gate insulating film, gate film, or barrier film for 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 impurity halogen content is preferably 100 ppm or less, more preferably 10 ppm or less, and most preferably 1 ppm or less. The total amount of impurity organic components is preferably 500 ppm or less, more preferably 50 ppm or less, and most preferably 10 ppm or less. Furthermore, since moisture is the cause of particle generation in the thin film forming raw materials and during thin film formation in the ALD method, it is preferable to remove moisture from the precursors, organic solvents, and nucleophilic reagents as much as possible before use to reduce their respective moisture content. The water content of the precursor, organic solvent and nucleophilic reagent is preferably below 10 ppm, and more preferably below 1 ppm.

[0053] The atomic layer deposition method of this invention uses thin film forming raw materials that are preferably as free of particles as possible in order to reduce or prevent particulate contamination of the formed thin film. Specifically, in the particle measurement by a light scattering liquid particle detector in the liquid phase, the number of particles larger than 0.3 μm in 1 mL of liquid phase is preferably less than 100, more preferably less than 1000, and most preferably less than 100.

[0054] The thin film manufacturing method of the present invention is a method of manufacturing a thin film containing yttrium atoms on the surface of a substrate by atomic layer deposition, and includes the steps of gasifying the thin film forming raw material of the above-mentioned atomic layer deposition method to adsorb (deposit) the yttrium compound in the resulting raw material gas onto the surface of the substrate to form a precursor thin film, and the steps of reacting the precursor thin film with a reactive gas to form a thin film containing yttrium atoms on the surface of the substrate.

[0055] Examples of substrate materials 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 cobalt, iron, manganese, nickel, and copper; and alloys such as stainless steel, brass, cupronickel, bronze, duralumin, nickel-chromium alloys, stellite, solder, amalgam, and carbon steel. Examples of substrate shapes include plate-like, spherical, fibrous, and flaky. The substrate surface can be planar or three-dimensional, such as grooved structures.

[0056] Furthermore, examples of methods for vaporizing the raw material used in the atomic layer deposition method and introducing the resulting raw material gas into the film-forming chamber of the substrate include the gas delivery method, liquid delivery method, single-source method, and mixed-source method.

[0057] Examples of the aforementioned reactive gases 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 pentanediamines; and nitriding gases such as hydrazine and ammonia. These reactive gases can be used alone or in mixtures of two or more. Among these, the thin film forming raw materials used in the atomic layer deposition method of the present invention have the property of reacting with oxidizing gases at particularly low temperatures, especially with ozone and water vapor at low temperatures. Regarding the possibility of producing thicker films per cycle and thus enabling productive thin film manufacturing, oxidizing gases containing ozone, oxygen, or water vapor are preferred as reactive gases, and oxidizing gases containing ozone are even more preferred.

[0058] As an example of the aforementioned manufacturing conditions, the temperature and pressure at which the raw material for atomic layer deposition (ALD) thin film formation is vaporized into a feed gas are further exemplified. The step of vaporizing the raw material for ALD thin film formation into a feed gas can be performed in a raw material container or in a vaporization chamber. In either case, the raw material for ALD thin film formation of the present invention is preferably vaporized at a temperature of 0°C to 300°C. Furthermore, when the raw material for ALD thin film formation is vaporized into a feed gas in a raw material container or in a vaporization chamber, the pressure in both the raw material container and the vaporization chamber is preferably 1 Pa to 10,000 Pa.

[0059] Furthermore, the manufacturing conditions in the method for manufacturing the thin film of the present invention are not particularly limited. For example, the reaction temperature (substrate temperature), reaction pressure, deposition rate, etc., can be appropriately determined according to the required thin film thickness and type. Regarding the reaction temperature, it is preferably 100°C or higher, which allows the raw materials for thin film formation to react sufficiently in the atomic layer deposition method of the present invention, and more preferably 150°C to 400°C, within the ALD range that matches the reactive gas. The film thickness is controlled by the number of cycles to obtain the desired film thickness.

[0060] The following details each step of the ALD method described above, using the formation of a yttrium oxide thin film as an example. First, the raw material for atomic layer deposition (ALD) is vaporized and introduced into the film formation chamber (raw material introduction step). The preferred temperature and pressure for vaporizing the raw material for ALD are within the range of 0°C to 300°C and 1 Pa to 10,000 Pa. Next, a precursor film is formed on the substrate surface by adsorbing (depositing) the raw material gas introduced into the film formation chamber onto the substrate surface (precursor film formation step). At this time, the substrate or the film formation chamber can be heated, or heat can be applied. The preferred substrate temperature for this step is room temperature to 500°C, more preferably 150°C to 400°C. The ALD range when using the atomic layer deposition method of the present invention with the raw material for thin film formation and the oxidizing gas is approximately 200°C to 400°C. The pressure in the system (film-forming chamber) during this step is preferably 1 Pa to 10,000 Pa, more preferably 10 Pa to 1,000 Pa.

[0061] Secondly, unreacted feed gas or byproduct gas is discharged from the film-forming chamber (exhaust step). Ideally, the unreacted feed gas or byproduct gas should be completely exhausted from the film-forming chamber, but complete exhaust is not necessary. Examples of exhaust methods include purging the system with inert gases such as nitrogen, helium, or argon, exhausting the system by reducing pressure, and a combination of these methods. The pressure reduction is preferably 0.01 Pa to 300 Pa, more preferably 0.01 Pa to 100 Pa.

[0062] Next, an oxidizing gas, serving as a reactive gas, is introduced into the film-forming chamber. Through the action of this oxidizing gas, or the action of the oxidizing gas and heat, a yttrium oxide film is formed from the precursor film forming step (yttrium oxide film forming step). The temperature for the heating action in this step is preferably room temperature to 500°C, more preferably 150°C to 400°C. Since the ALD range when using the atomic layer deposition method of the present invention with the film-forming raw material and the oxidizing gas is approximately 200°C to 400°C, the reaction between the precursor film and the oxidizing gas is preferably carried out within the range of 200°C to 400°C. The pressure of the system (within the film-forming chamber) during this step is preferably 1 Pa to 10,000 Pa, more preferably 10 Pa to 1,000 Pa. The atomic layer deposition method of the present invention exhibits good reactivity between the film-forming raw material and the oxidizing gas, enabling the productive production of high-quality yttrium oxide films with low residual carbon content.

[0063] In the thin film manufacturing method of the present invention, the thin film deposition resulting from a series of operations including the raw material introduction step, the precursor thin film formation step, the venting step, and the yttrium oxide thin film formation step is defined as one cycle. This cycle is repeated several times until a thin film of the desired thickness is obtained. In this case, it is preferable that after performing one cycle, similar to the venting step described above, unreacted reactive gases (oxidizing gases during yttrium oxide thin film formation) and byproduct gases are discharged from the film formation chamber before proceeding to the next cycle.

[0064] Furthermore, the method for manufacturing the thin film of the present invention can also apply energy such as plasma, light, or voltage, and a catalyst can also be used. The timing of applying the energy and the timing of using the catalyst are not particularly limited. For example, it can be applied during the introduction of the raw material gas in the raw material introduction step, during heating in the precursor film formation step or the yttrium oxide film formation step, during internal venting in the venting step, during the introduction of the oxidizing gas in the yttrium oxide film formation step, or between the above steps.

[0065] Furthermore, in the thin film manufacturing method of the present invention, after the thin film is formed, in order to obtain better electrical properties, annealing treatment can be performed in an inert environment, an oxidizing environment, or a reducing environment. When a step embedding is required, a reflow step can also be provided. The temperature in this case is 200℃~1,500℃, preferably 500℃~1,000℃.

[0066] The apparatus for manufacturing thin films using the atomic layer deposition method of the present invention with thin film forming raw materials can use known atomic layer deposition apparatus. Examples of specific apparatuses include an apparatus for supplying precursors via gas flow, as shown in Figure 1, or an apparatus with a vaporization chamber, as shown in Figure 2. Also, examples include apparatuses for plasma treatment of reactive gases, as shown in Figures 3 and 4. Not limited to single-film apparatuses as shown in Figures 1-4, apparatuses utilizing batch furnaces that can process multiple films simultaneously can also be used.

[0067] Thin films manufactured using the atomic layer deposition method of this invention, derived from thin film forming materials, can be of desired types, such as metals, oxide ceramics, nitride ceramics, and glasses, by appropriately selecting other precursors, reactive gases, and manufacturing conditions. These thin films are known to exhibit electrical and optical properties and are applied in various applications. For example, they can be widely used in the manufacture of electrode materials for memory devices, such as DRAM devices, resistive films, antimagnetic films used in the recording layers of hard disks, and catalyst materials for solid polymer fuel cells. [Example]

[0068] The present invention will now be described in more detail using examples, evaluation examples, and comparative examples. However, the present invention is not limited to the following examples. [Example 1] Synthesis of Compound No. 3 50 g (0.131 mol) of yttrium hexahydrate and 200 mL of methanol were added to a 1 L four-necked flask and stirred at room temperature. A solution prepared from 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 at room temperature for 19 hours, the solvent was removed from the resulting suspension, and 500 mL of dehydrated toluene was added. Dehydration was carried out 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 yttrium complex was distilled at a bath temperature of 210 °C and a pressure of 44 Pa to obtain compound No. 3, a yellow, transparent, viscous liquid (yield 82.03 g, 82.1%).

[0069] (Analysis value) (1) Atmospheric pressure TG-DTA Mass reduction of 50% at temperature: 305℃ (760 Torr, Ar flow rate: 100 mL / min, heating rate: 10℃ / min, sample volume: 9.860 mg) (2) Decompression TG-DTA Mass reduction of 50% at temperature: 215℃ (10 Torr, Ar flow rate: 50 mL / min, heating rate: 10℃ / min, sample volume: 9.716 mg) (3) 1H-NMR (deuterated benzene) 0.91~0.97ppm (6H, multi-peak), 1.18ppm (9H, single-peak), 1.26~1.48ppm (6H, multi-peak), 1.71~1.78ppm (2H, multi-peak), 2.07-2.14ppm (1H, multi-peak), 5.76ppm (1H, single-peak) (4) Elemental analysis (metal analysis: ICP-AES) Yttrium content: 11.6% by mass (theoretical value: 11.6% by mass)

[0070] [Evaluation Example] The following evaluation was performed on Compound No. 3 obtained in Example 1 and the comparative compound 1 described below. Also, in the comparative compound 1 described below, "tBu" represents the third butyl group. (1) Melting point evaluation The state of the compounds was visually observed at 20°C. For compounds that were solid at 20°C, the melting point was determined using a micro melting point apparatus. The results are shown in Table 1. (2) Thermal stability evaluation The thermal decomposition onset temperature was determined using a DSC (Digital Subtraction Angiography) device. Temperatures with higher thermal decomposition onset temperatures indicate less likelihood of thermal decomposition and are thus considered better raw materials for thin film formation in atomic layer deposition (ALD) methods. The results are shown in Table 1.

[0071]

[0072]

[0073] As shown in Table 1, compound No. 3 has a melting point that is more than 150°C lower than that of comparative compound 1. Furthermore, compound No. 3 exhibits higher thermal stability than comparative compound 1. Compared to comparative compound 1, which has a similar structure, compound No. 3 is highly suitable as a raw material for thin film formation in atomic layer deposition (ALD).

[0074] [Example 2] Fabrication of yttrium oxide thin film Compound No. 3 was used as a raw material for atomic layer deposition (ALD) thin film formation. Using the apparatus shown in Figure 1, yttrium oxide thin films were fabricated on silicon wafers under the following conditions. After confirming the composition of the obtained film by X-ray photoelectron spectroscopy, the film was found to be yttrium oxide with a residual carbon content of less than 1.0 atom%. The film thickness was measured by X-ray reflectance measurement, and the average film thickness was calculated to be 15.0 nm, with an average film thickness of 0.05 nm per cycle.

[0075] (condition) Substrate: Silicon wafer; Reaction temperature (silicon wafer temperature): 300℃; Reactive gas: Ozone The sequence of steps (1) to (4) below is set as 1 cycle, and the cycle is repeated 300 times. (1) Raw material container temperature: 200℃, raw material container pressure: the vaporized raw material gas is introduced into the membrane formation chamber under 100Pa conditions, system pressure: deposition for 10 seconds under 100Pa conditions. (2) Remove the undeposited raw material gas by 15 seconds of argon blowing. (3) Introduce the reactive gas into the membrane chamber, system pressure: react at 100 Pa for 10 seconds. (4) Remove unreacted reactive gases and byproduct gases by blowing argon for 15 seconds.

[0076] [Comparative Example 1] Fabrication of Yttrium Oxide Thin Film Except that Comparative Compound 1 was used as the raw material for thin film formation in atomic layer deposition, yttrium oxide thin films were manufactured under the same conditions as in Example 2. After confirming the composition of the obtained thin film by X-ray photoelectron spectroscopy, the film was found to be yttrium oxide with a residual carbon content of 3.0 atom%. Furthermore, the film thickness was measured by X-ray reflectance method, and the average film thickness was calculated to be 9.0 nm, with an average film thickness of 0.03 nm per cycle.

[0077] As can be seen from the results of Example 2 and Comparative Example 1, the film thickness obtained per cycle in Example 2 is more than 1.6 times that of Comparative Example 1, and high-quality yttrium oxide films with low residual carbon content can be obtained with good productivity. From the above, it can be said that high-quality yttrium oxide thin films can be manufactured with good productivity according to the present invention.

Claims

1. A method for manufacturing a thin film, comprising a method for forming a thin film containing yttrium atoms on the surface of a substrate by atomic layer deposition, and including the steps of gasifying a thin film forming raw material containing yttrium compound in the atomic layer deposition process to adsorb the aforementioned yttrium compound onto the surface of the substrate to form a precursor thin film, and the steps of reacting the aforementioned precursor thin film with a reactive gas to form a thin film containing yttrium atoms on the surface of the substrate, wherein the aforementioned thin film forming raw material in the atomic layer deposition process is represented by the following general formula (1), the aforementioned reactive gas is an oxidizing gas, the aforementioned oxidizing gas system contains ozone, oxygen or water vapor, and the aforementioned precursor thin film is reacted with the aforementioned reactive gas in a temperature range of 200°C to 400°C.

1. (In the formula, R1 represents hept-2-yl or hept-3-yl, R2 represents a tertiary alkyl group with 4 carbon atoms, and R3 represents a hydrogen atom).

2. The method for manufacturing the thin film as claimed in claim 1, wherein the aforementioned yttrium compound is yttrium compound No. 3 below.

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