Thin film manufacturing method and starting material for thin film formation by atomic layer deposition

Abstract

The present invention is: a thin film manufacturing method in which a cobalt metal thin film is formed on a substrate by a plasma ALD method (plasma enhanced ALD), said method comprising a precursor thin film formation step for forming a precursor thin film by bringing the substrate into contact with vapor of a starting material for thin film formation containing a compound represented by general formula (A), and a metal film formation step for forming a cobalt metal thin film by reacting the precursor thin film with a reactive material converted into plasma, wherein the reactive material contains a reducing gas; and a starting material for thin film formation by atomic layer deposition. (In the formula, R1-R6 each independently represent a hydrogen atom or an alkyl group having a C1-5 linear or branched chain, and m represents an integer of 0 or more.)

Description

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

[0001] The present invention relates to a method for producing a thin film and a raw material for forming a thin film by atomic layer deposition.

[0002] As semiconductor devices become more highly integrated, there is an increasing demand for miniaturized wiring. Copper has a relatively long mean free path for free electrons, so miniaturization increases the surface and interface scattering and grain boundary scattering of conduction electrons, significantly increasing the electrical resistivity of copper wiring. For this reason, in recent years, research has been conducted into replacing the wiring metal with cobalt, which has a shorter mean free path.

[0003] Regarding the formation of wiring, a thin film manufacturing method capable of forming a conformal film on complex step shapes as wiring is desired. Chemical vapor deposition methods such as CVD and ALD are known to be techniques with excellent step shape coverage. For example, Patent Document 1 discloses the formation of a cobalt oxide thin film on a Cu substrate by thermal CVD using a cobalt compound with an aminoalkoxide structure as a thin film formation raw material. Patent Document 2 discloses the formation of a cobalt metal thin film on a silicon wafer substrate by CVD using a specific cobalt alkoxide compound. Patent Document 3 discloses the formation of a conductive layer for a solar cell having a transparent electrode by ALD using Co(dmamb)2.

[0004] International Publication No. 2015 / 174153 Japanese Patent Application Laid-Open No. 2013-216614 International Publication No. 2010 / 085081

[0005] However, as semiconductor devices continue to become more highly integrated, there is an increasing demand for a method for producing a thin film that can form cobalt metal wiring with reduced electrical resistivity.

[0006] Therefore, an object of the present invention is to provide a method for producing a thin film that can form wiring with reduced electrical resistivity, and a thin film-forming raw material for atomic layer deposition that can be used in the thin film production method.

[0007] As a result of intensive research into solving the above problems, the present inventors have found that the above problems can be solved by a method for producing a thin film that uses a specific compound as a thin film-forming raw material, and have thus completed the present invention.

[0008] That is, the present disclosure provides a thin film manufacturing method for forming a cobalt metal thin film on a substrate by a plasma-enhanced ALD method, the method comprising: a precursor thin film formation step of contacting the substrate with vapor of a thin film-forming raw material containing a compound represented by the following general formula (A) to form a precursor thin film; and a metal film formation step of contacting the precursor thin film with a plasmatized reactive material to form a cobalt metal thin film, wherein the reactive material contains a reducing gas.

[0009] (In the formula, R 1 ~R 6 each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms, and m represents an integer of 0 to 5.

[0010] The present disclosure also provides a method for producing a thin film according to claim 1, wherein the compound represented by general formula (A) is a compound represented by the following general formula (1):

[0011] (In the formula, R 1 and R 2 each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms; R 3 and R 4 each independently represents a linear or branched alkyl group having 1 to 5 carbon atoms.

[0012] The present disclosure provides a thin film-forming material for atomic layer deposition, which contains a compound represented by the above general formula (A), preferably a compound represented by the above general formula (1).

[0013] The present disclosure provides a method for producing a thin film that can form a cobalt metal thin film with low electrical resistivity, and a thin film-forming raw material for atomic layer deposition that is used in this production method.

[0014] 1 is a schematic diagram showing an example of an ALD apparatus used in a method for producing a thin film according to the present invention, and FIG. 2 is a schematic diagram showing another example of an ALD apparatus used in a method for producing a thin film according to the present invention.

[0015] The method for producing a thin film according to the present disclosure will be described below. First, the thin film-forming raw materials used in the method for producing a thin film according to the present disclosure will be described.

[0016] A. Thin Film-Forming Raw Material The thin film-forming raw material contains the compound represented by the general formula (A) above as a precursor.

[0017] A1. Compound represented by general formula (A) In the above general formula (A), R 1 ~R 6 each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms.

[0018] Examples of the linear alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group (an n-amyl group), etc. Examples of the branched alkyl group having 1 to 5 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an isopentyl group (an isoamyl group), a sec-pentyl group (a sec-amyl group), a tert-pentyl group (a tert-amyl group), and a neopentyl group.

[0019] In the present disclosure, from the viewpoint of obtaining a compound having a low melting point, good vapor properties, and excellent thermal stability, R 1 and R 2 is preferably a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. 1 and R 2 When R is not a hydrogen atom, the electrical resistivity is small and it is easy to form a continuous thin film with a uniform thickness. 1 or R 2 is preferably a linear or branched alkyl group having 1 to 3 carbon atoms, and R 1 and R 2More preferably, R are both ethyl groups, a methyl group and an isopropyl group, or a combination of a methyl group and an ethyl group. 1 or R 2 When R is a hydrogen atom, the other is preferably an alkyl group having a branched chain with 3 or 4 carbon atoms, more preferably an alkyl group having a branched chain with 4 carbon atoms, and even more preferably a tert-butyl group, from the viewpoint of facilitating the formation of a continuous thin film having a small electrical resistivity and a uniform thickness. 1 and R 2 However, it is most preferable that both groups are ethyl groups, or a combination of a methyl group and an ethyl group, a methyl group and an isopropyl group, or a combination of hydrogen and a tert-butyl group. Here, the continuous thin film refers to a thin film having no voids such as pinholes on the surface.

[0020] In the present disclosure, from the viewpoint of facilitating the formation of a continuous thin film having a small electrical resistivity and a uniform thickness, R 3 and R 4 is preferably a linear or branched alkyl group having 1 to 5 carbon atoms, more preferably a linear or branched alkyl group having 1 to 4 carbon atoms, even more preferably a linear or branched alkyl group having 1 to 3 carbon atoms, particularly preferably a methyl group or an ethyl group, and most preferably both are methyl groups or a combination of an ethyl group and a methyl group.

[0021] In the present disclosure, from the viewpoint of facilitating the formation of a continuous thin film having a small electrical resistivity and a uniform thickness, R 5 and R 6 is preferably a hydrogen atom or a linear or branched alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom, a methyl group or an ethyl group, and particularly preferably both are hydrogen atoms.

[0022] In the present disclosure, from the viewpoint of facilitating the formation of a continuous thin film with low electrical resistivity and uniform thickness, m is preferably an integer of 0 to 4, more preferably an integer of 0 to 2, and most preferably 1. When m is 1 and R 5 and R6 is a hydrogen atom, the compound represented by the general formula (A) above becomes the compound represented by the general formula (1) above.

[0023] Preferred specific examples of the compound represented by the general formula (1) above include compounds No. 1 to No. 39 below. However, the present invention is not limited to these compounds. In the chemical formulas below, "Me" represents a methyl group, "Et" represents an ethyl group, "nPr" represents an n-propyl group, "iPr" represents an isopropyl group, "nBu" represents an n-butyl group, "iBu" represents an isobutyl group, "sBu" represents a sec-butyl group, and "tBu" represents a tert-butyl group.

[0024]

[0025]

[0026]

[0027]

[0028]

[0029]

[0030]

[0031]

[0032]

[0033]

[0034] In the present disclosure, from the viewpoint of facilitating the formation of a continuous thin film having a small electrical resistivity and a uniform thickness, R 1 and R 2 The total number of carbon atoms in is preferably 1 or more and 5 or less, more preferably 2 or more and 4 or less, even more preferably 3 or more and 4 or less, and particularly preferably 4.

[0035] In the present disclosure, from the viewpoint of facilitating the formation of a continuous thin film having a small electrical resistivity and a uniform thickness, R 1 , R2 , R 3 and R 4 The total number of carbon atoms is preferably 3 or more and 8 or less, more preferably 6 or more and 8 or less, and even more preferably 6 or more and 7 or less.

[0036] The above R 1 , R 2 , R 3 and R 4 Examples of compounds having a total number of carbon atoms of 6 or more and 8 or less include the above-mentioned Compound No. 6, Compound No. 8, Compound No. 9, Compound Nos. 11 to 24, Compound No. 27, and Compound Nos. 29 to 39. From the viewpoint of being able to form a thin film with low electrical resistivity, Compound No. 6, Compound No. 8, Compound No. 9, Compound No. 11, Compound No. 12, Compound No. 13, Compound No. 16, Compound No. 19, Compound No. 22, Compound No. 23, Compound No. 24, Compound No. 27, Compound No. 29, Compound No. 31, Compound No. 34, Compound No. 35, and Compound No. 37 are preferred, and Compound No. 11, Compound No. 12, Compound No. 36, and Compound No. 37 are also preferred. Compound No. 23, Compound No. 24, Compound No. 29, Compound No. 34, and Compound No. 37 are more preferred, Compound No. 23, Compound No. 29, Compound No. 34, and Compound No. 37 are even more preferred, and Compound No. 23 and Compound No. 37 are particularly preferred.

[0037] A2. Other Components The thin film-forming raw material may contain a compound represented by the general formula (A), and the composition may vary depending on the type of thin film to be formed. For example, other components may be included in the thin film-forming raw material as needed. Examples of the other components include other precursors and nucleophilic reagents, which will be described later.

[0038] (a) Other precursor The other precursor may be a precursor different from the compound represented by the general formula (A). From the viewpoint of forming a cobalt metal thin film with few impurities, the metal atom constituting the other precursor is preferably cobalt, the same as that of the compound represented by the general formula (A).

[0039] The thin film-forming raw material may contain other precursors, which may be well-known precursors, such as coordination compounds of cobalt atoms with one or more compounds selected from compounds used as organic ligands, such as alcohol compounds, glycol compounds, β-diketone compounds, cyclopentadiene compounds, and organic amine compounds.

[0040] 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, and 2-isopropoxy-1,1-dimethylethanol. ether alcohols such as 2-butoxy-1,1-dimethylethanol, 2-(2-methoxyethoxy)-1,1-dimethylethanol, 2-propoxy-1,1-diethylethanol, 2-sec-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.

[0041] Examples of glycol compounds 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.

[0042] Examples of the β-diketone compound used as the organic ligand of the other precursor 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 alkyl-substituted β-diketones such as 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.

[0043] Examples of the cyclopentadiene compound used as the organic ligand of the other precursor include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, propylcyclopentadiene, isopropylcyclopentadiene, butylcyclopentadiene, sec-butylcyclopentadiene, isobutylcyclopentadiene, tert-butylcyclopentadiene, dimethylcyclopentadiene, tetramethylcyclopentadiene, and pentamethylcyclopentadiene.

[0044] Examples of the organic amine compound used as the organic ligand of the other precursor include methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, tert-butylamine, isobutylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, ethylmethylamine, propylmethylamine, and isopropylmethylamine.

[0045] The 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 other precursor can be produced by reacting an inorganic salt of cobalt or a hydrate thereof with an alkali metal alkoxide of the alcohol compound, or by reacting an amide compound of cobalt with an alcohol organic ligand. Examples of inorganic salts of cobalt include halides and nitrates of cobalt. Examples of alkali metal alkoxides include sodium alkoxides, lithium alkoxides, and potassium alkoxides.

[0046] In the method for producing a thin film according to the present disclosure, when the other precursors are used as raw materials for forming a thin film, it is preferable that the other precursors are compounds whose thermal decomposition and / or oxidative decomposition behavior is similar to that of the compound represented by general formula (A) above, from the viewpoint of facilitating the formation of a high-purity cobalt metal thin film that has a high film formation rate, a uniform film thickness, and little residual carbon and residual oxygen.

[0047] In the method for producing a thin film according to the present disclosure, when a mixture of the compound represented by the general formula (A) and the other precursor is used as the thin film-forming raw material, from the viewpoint of facilitating the formation of a high-purity cobalt metal thin film having a high film formation rate, a uniform film thickness, and little residual carbon and residual oxygen, it is preferable that the other precursor exhibits similar thermal decomposition and / or oxidative decomposition behavior to the compound represented by the general formula (A) and is also a compound that does not undergo deterioration due to a chemical reaction or the like after being mixed with the compound represented by the general formula (A).

[0048] In the thin film manufacturing method of the present disclosure, when the thin film forming raw material contains the above-mentioned other precursors, from the viewpoint of facilitating the formation of a high-purity cobalt metal thin film that has a high film formation rate, a uniform film thickness, and little residual carbon and residual oxygen, the content of the above-mentioned other precursors is preferably 50 parts by mass or less, more preferably 30 parts by mass or less, even more preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and most preferably 0 parts by mass, i.e., the thin film forming raw material does not contain any other precursors.

[0049] (b) Nucleophilic Reagent In the method for producing a thin film of the present disclosure, a nucleophilic reagent can be contained in the thin film-forming raw material in order to promote the reaction between the compound represented by the general formula (A) or the other precursor and the reducing gas.

[0050] 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, and 1,1,4,7,10,10-hexamethyltriethylenetetramine. , polyamines such as triethoxytriethyleneamine, 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.

[0051] When the thin film-forming raw material contains the nucleophilic reagent, the content of the nucleophilic reagent is preferably 0.1 mol or more and 10 mol or less, and more preferably 1 mol or more and 4 mol or less, relative to 1 mol of the total amount of precursors, from the viewpoint of facilitating control of the reaction between the compound represented by general formula (A) or the other precursor and the reducing gas described later.

[0052] Here, the total amount of precursors refers to the total amount of precursors contained in the thin film-forming raw material, and refers to the total amount of the compound represented by general formula (A) and the other precursors. When the thin film-forming raw material does not contain the other precursors, the total amount of precursors refers to the amount of the compound represented by general formula (A).

[0053] (c) Impurities The thin film-forming raw material may contain impurities other than the above-mentioned components, i.e., the compound represented by the general formula (A), the other precursors, and the nucleophilic reagent, which constitute the thin film-forming raw material. Examples of the impurities include impurity metal atoms, impurity halogens, impurity organic components, etc.

[0054] Examples of the impurity metal atoms include compounds containing metal atoms other than cobalt. From the viewpoint of forming a cobalt metal thin film with low metal resistivity, the content of the impurity metal atoms is preferably 1 ppt or more and 10 ppm or less, more preferably 1 ppt or more and 1 ppm or less, and particularly preferably 1 ppt or more and 100 ppb or less, in the thin film-forming raw material. The content of the impurity metal atoms can be analyzed using ICP-MS.

[0055] The impurity halogen may be, for example, a halogen gas or a halogen compound. From the viewpoint of forming a cobalt metal thin film having low metal resistivity, the content of the impurity halogen in the thin film-forming raw material is preferably 100 ppm or less, more preferably 10 ppm or less, and even more preferably 1 ppm or less.

[0056] The impurity organic components include compounds containing carbon and oxygen, excluding carbon monoxide and carbon dioxide, and organic substances excluding the compound represented by general formula (A) and the other precursors. From the viewpoint of forming a cobalt metal thin film having low metal resistivity, the content of the impurity organic components in the thin film-forming raw material is preferably 500 ppm or less in total, more preferably 50 ppm or less, and even more preferably 10 ppm or less.

[0057] In the thin film-forming raw material, moisture causes particle generation in the thin film-forming raw material and during thin film formation, so it is preferable to remove moisture from the compound represented by general formula (A), the other precursor, and the nucleophilic reagent before use in order to reduce the moisture content of each. The moisture content of the compound represented by general formula (A), the other precursor, and the nucleophilic reagent is preferably 10 ppm or less, and more preferably 1 ppm or less, respectively.

[0058] Furthermore, in order to reduce or prevent particle contamination of the thin film to be formed, it is preferable that the thin film-forming raw material contains as few particles as possible. Specifically, in particle measurement in the liquid phase using a light scattering liquid-borne particle detector, it is preferable that the number of particles larger than 0.3 μm per 1 ml of liquid phase is 100 or less, and it is more preferable that the number of particles larger than 0.2 μm per 1 ml of liquid phase is 100 or less.

[0059] Among the compounds represented by the general formula (A), the compounds represented by the general formula (1) are useful as raw materials for chemical vapor deposition. 1 , R 2 , R 3 and R 4 A thin film-forming raw material containing a compound having 6 or more carbon atoms in total can be easily formed into a continuous thin film having low metal resistivity and uniform thickness, and is therefore useful as a thin film-forming raw material for atomic layer deposition, and is particularly useful as a thin film-forming raw material for plasma ALD.

[0060] The thin film-forming material of the present disclosure can form thin films with excellent electrical and optical properties, and these thin films are useful in various semiconductor devices, for example, as electrodes or contact layers. The thin film-forming material of the present disclosure is particularly useful as a thin film-forming material for wiring in logic semiconductors.

[0061] B. Thin Film Manufacturing Method Next, a thin film manufacturing method according to the present disclosure will be described. The present disclosure provides a thin film manufacturing method for forming a cobalt metal thin film on a substrate by a plasma ALD method, which uses a compound represented by the above general formula (A) and a reducing gas.

[0062] The apparatus used in the thin film manufacturing method of the present disclosure may be a well-known ALD apparatus. As shown in Figures 1 and 2, the apparatus is capable of performing plasma processing, and may be an apparatus capable of supplying thin film forming raw materials by bubbling as shown in Figure 1, or an apparatus having a vaporization chamber 102 as shown in Figure 2. The apparatus is not limited to a single-wafer apparatus equipped with a film formation chamber 100 as shown in Figures 1 and 2, but may also be an apparatus capable of simultaneously processing multiple wafers using a batch furnace.

[0063] The present disclosure relates to a method for producing a thin film using a plasma ALD method, and examples of the method include a precursor thin film formation step of introducing a vapor obtained by vaporizing a thin film-forming raw material containing the compound represented by the general formula (A) into a film formation chamber 100 and depositing the compound represented by the general formula (A) contained in the vapor on the surface of a substrate S to form a precursor thin film, and a metal film formation step of forming a cobalt metal thin film by reacting the precursor thin film with a plasma-converted reactive material in the film formation chamber 100.

[0064] Each step of the method for producing a thin film according to the present disclosure will be described below with reference to FIGS. 1 and 2. FIG.

[0065] B1. Precursor thin film formation step In this step, the vapor obtained by vaporizing the thin film forming raw material M containing the compound represented by the general formula (A) is introduced into the film formation chamber 100, and the compound represented by the general formula (A) in the vapor of the thin film forming raw material M is deposited on the surface of the substrate S to form a precursor thin film.

[0066] (a) Substrate The substrate S is not particularly limited as long as it can support the precursor thin film, and may be any known substrate. The substrate S may be, for example, an organic compound or an inorganic compound. However, ceramic substrates such as silicon substrates, SiN, TiN, TaN, AlN, Al2O3, ZrO2, HfO2, and La2O3; low-k substrates such as SiON, SiOC, and SiOCN; glass substrates such as SiO2; and metal substrates such as copper, manganese, and ruthenium are preferred because they facilitate the formation of a precursor thin film with a uniform thickness. The substrate S may also be formed from multiple materials, such as a silicon substrate coated with a ceramic such as TaN. The shape of the substrate S may be, for example, plate-like, spherical, fibrous, scale-like, disc-like, cylindrical, prismatic, tubular, spiral, ring-like, or trench-shaped. In the thin film manufacturing method of the present disclosure, from the viewpoint of facilitating the formation of a continuous thin film having low electrical resistivity and uniform thickness, the substrate S is preferably a substrate selected from a ceramic substrate, a low-k substrate, and a metal substrate as an underlayer for the cobalt metal thin film, more preferably a substrate made of a ceramic substrate, and particularly preferably a substrate containing silicon or TaN. Examples of substrates containing silicon include silicon oxide substrates in which a silicon oxide film is formed on the surface of a silicon substrate.

[0067] (b) Introduction of Thin Film-Forming Raw Material In the thin film manufacturing method of the present disclosure, thin film-forming raw material M containing the compound represented by the general formula (A) is introduced into the film formation chamber 100 as vapor obtained by vaporizing the thin film-forming raw material M. Examples of methods for vaporizing the thin film-forming raw material M include a method in which the thin film-forming raw material M containing the compound represented by the general formula (A) is heated and / or decompressed.

[0068] Examples of methods for heating the thin film forming raw material M include a method of heating the thin film forming raw material M by a heater 103 or the like in a raw material container 101 in the ALD apparatus shown in Fig. 1, and a method of heating the thin film forming raw material M in a vaporization chamber 102 in the ALD apparatus shown in Fig. 2. The temperature range for heating the thin film forming raw material M is, from the viewpoint of facilitating the formation of a continuous thin film of high-purity cobalt metal thin film that has a high film formation rate, a uniform film thickness, and little residual carbon and oxygen, preferably 200°C or less, more preferably room temperature or higher and 180°C or lower, and even more preferably 50°C or higher and 150°C or lower.

[0069] Examples of methods for reducing the pressure of the thin film forming raw material M include a method of reducing the pressure of the thin film forming raw material M in the raw material container 101 of the ALD apparatus shown in Fig. 1 or 2, or a method of reducing the pressure of the thin film forming raw material M in the vaporization chamber 102 of the ALD apparatus shown in Fig. 2. The reduced pressure (degree of vacuum) conditions are, for example, preferably from 1 Pa to 10,000 Pa, more preferably from 5 Pa to 5,000 Pa, and even more preferably from 10 Pa to 1,000 Pa, from the viewpoint of facilitating the formation of a continuous high-purity cobalt metal thin film that has a high film formation rate, a uniform film thickness, and little residual carbon and oxygen.

[0070] Methods for introducing the thin film forming raw material M into the film formation chamber 100 include gas transport and liquid transport. As shown in FIG. 1 , the gas transport method involves heating and / or vaporizing the thin film forming raw material M in a raw material container 101 to produce vapor, and then introducing the vapor into the film formation chamber 100, optionally together with a carrier gas 201 such as argon, nitrogen, or helium. As shown in FIG. 2 , the liquid transport method involves transporting the thin film forming raw material M in a liquid or solution state to a vaporization chamber 102, heating and / or decompressing the thin film forming raw material M in the vaporization chamber 102 to produce vapor, and then introducing the vapor into the film formation chamber 100, optionally together with the carrier gas 201. The flow rates of each gas are adjusted by a mass flow controller (MFC) 104. When the thin film forming raw material M contains the other precursors, the thin film forming raw material M can be introduced into the film formation chamber 100, for example, using a single source method.

[0071] (c) Formation of Precursor Thin Film In the precursor thin film formation step, as described above, the compound represented by general formula (A) in the vapor of the thin film forming raw material M introduced into the film formation chamber 100 is deposited on the surface of the substrate S previously placed in the film formation chamber 100 to form a precursor thin film. In the present disclosure, "depositing" refers to a concept that includes both chemical adsorption of the compound represented by general formula (A) on the surface of the substrate and chemical adsorption of the compound represented by general formula (A) on the cobalt metal thin film formed on the substrate S by the ALD cycle described below.

[0072] In this step, the interior of the film formation chamber 100 and / or the substrate S are heated. From the viewpoint of facilitating the formation of a continuous high-purity cobalt metal thin film that has a high film formation rate, a uniform film thickness, and little residual carbon and oxygen, the heating is preferably carried out at a temperature of, for example, 25° C. or higher and 500° C. or lower.

[0073] In this step, the heating is preferably carried out in an oxygen-free atmosphere, from the viewpoint of facilitating the formation of a continuous, high-purity cobalt metal thin film that has a high film formation rate, a uniform film thickness even for a very thin film, and little residual carbon and oxygen, and is more preferably carried out in an inert gas atmosphere, and even more preferably in an inert gas atmosphere containing nitrogen gas or argon gas. Furthermore, the heating reaction may be carried out under any of conditions of increased pressure, reduced pressure, normal pressure, and atmospheric pressure, but in this step, it is preferably carried out under reduced pressure (5 Pa to 1,000 Pa).

[0074] B2. Metal Film Formation Step In this step, the precursor thin film in the film formation chamber 100 reacts with the reactive material in plasma form, or with the reactive material in plasma form in combination with heating, causing the precursor thin film, i.e., the compound represented by general formula (A) deposited on the substrate S, to react and form a cobalt metal thin film.

[0075] The reactive material contains a reducing gas. Examples of the reducing gas include ammonia (NH3) gas, hydrogen gas, etc. In the present disclosure, the reactive material preferably contains hydrogen gas as the reducing gas, and particularly preferably contains a mixed gas of hydrogen gas and nitrogen gas. This is because it facilitates the formation of a high-purity cobalt metal thin film with a high film formation rate, a uniform film thickness, and little residual carbon and oxygen.

[0076] (a) Introduction of Reactive Material The reactive material is introduced into the film formation chamber 100 to react with the precursor thin film in the film formation chamber 100. Examples of a method for introducing the reactive material into the film formation chamber 100 include the method described above in "B1. Precursor Thin Film Formation Step" in which the reactive material is introduced into the film formation chamber 100 via a pipe together with a carrier gas as needed. When the reactive material contains multiple components, the components may be mixed and introduced into the film formation chamber 100 via the same pipe, or the components may be introduced into the film formation chamber 100 sequentially or alternately via the same pipe, or the components may be introduced into the film formation chamber 100 via different pipes.

[0077] (b) Plasma-converted reactive material The plasma-conversion may be, for example, a treatment method in which high-frequency power is generated using a DC current, an alternating current (RF) current, microwaves, or the like, and the high-frequency power is applied to the reactive material to generate plasma in the reactive material. The frequency of the high-frequency power may be, for example, 450 KHz to 60 MHz, and when the frequency is set to 13.56 MHz, the applied power may be, for example, 10 W to 2,000 W. In this step, the reactive material may be converted into plasma before being introduced into the film formation chamber 100, or the reactive material may be converted into plasma in the film formation chamber 100.

[0078] (c) Formation of cobalt metal thin film In this step, the reducing gas generated by plasma in the reactive material reacts with the compound represented by general formula (A) in the precursor thin film to form a cobalt metal thin film. The temperature and pressure in the film formation chamber 100 in this step can be set under the conditions described in the section "B1. Precursor thin film formation step (c) Formation of precursor thin film" above.

[0079] B3. Other Steps The method for producing a thin film according to the present disclosure may include other steps such as an evacuation step 1, an evacuation step 2, an annealing treatment step, and a reflow step.

[0080] (a) Exhaust Step 1: In the present disclosure, it is preferable to further include an exhaust step 1, in which undeposited vapor of the thin film-forming raw material M is exhausted from the reaction system after the precursor thin film-forming step. This facilitates the formation of a high-purity cobalt metal thin film with minimal residual carbon and oxygen. This step is a step of exhausting (203) the vapor of unreacted thin film-forming raw material M that was not involved in the formation of the precursor thin film from the film-forming chamber 100 after the precursor thin film-forming step. Ideally, in this step, the unreacted thin film-forming raw material M is completely exhausted from the film-forming chamber 100, but complete exhaust is not necessary. Examples of exhaust methods include purging the film-forming chamber 100 with an inert gas (purge gas 204) such as helium, nitrogen, or argon; exhausting the system by reducing the pressure while controlling the degree of vacuum using a vacuum pump 107 and an automatic pressure controller 108; and a combination of these methods. The exhausted vapor of unreacted thin film-forming raw material M is liquefied in a cold trap 109. The degree of vacuum when the system is depressurized is, for example, preferably from 0.01 Pa to 300 Pa, more preferably from 0.05 Pa to 200 Pa, and even more preferably from 0.1 Pa to 150 Pa. This is because the thin film-forming raw material M is sufficiently evacuated, the precursor thin film is formed at a high rate, the film thickness is uniform, and a high-purity cobalt metal thin film with little residual carbon and oxygen can be easily formed.

[0081] (b) Exhaust Step 2 This step is a step of exhausting (203) from the deposition chamber 100 any unreacted reactive material that has not been involved in the formation of the cobalt metal thin film and any by-product gases generated by the reaction between the precursor thin film and the reactive material, after the metal film formation step. In this step, it is ideal that the unreacted reactive material and by-product gases are completely exhausted from the deposition chamber 100, but complete exhaust is not necessarily required. The exhaust method, pressure reduction degree, and processing time can be the same as those in Exhaust Step 1.

[0082] (c) Annealing Step The annealing step can be a step of annealing the cobalt metal thin film after its formation in order to improve the electrical properties of the cobalt metal thin film. In the annealing step, the cobalt metal thin film can be annealed in an inert atmosphere or a reducing atmosphere. In this step, from the viewpoint of facilitating the formation of a continuous high-purity cobalt metal thin film with a high film formation rate, a uniform film thickness, and little residual carbon and oxygen, the temperature of the substrate S in the annealing step is preferably 100°C or higher and 450°C or lower, more preferably 150°C or higher and 400°C or lower, and even more preferably 200°C or higher and 400°C or lower.

[0083] (d) Reflow Process The reflow process can be a process of heating the cobalt metal thin film after its formation in order to fill up any steps in the cobalt metal thin film. The temperature in the reflow process is, for example, preferably 200°C or higher and 600°C or lower, more preferably 230°C or higher and 550°C or lower, and even more preferably 250°C or higher and 500°C or lower, from the viewpoint of facilitating the formation of a continuous high-purity metal thin film that has a high film formation rate, a uniform film thickness, and little residual carbon and oxygen.

[0084] B4. Film Formation Cycle In the present disclosure, after the metal thin film formation step, the method preferably further includes an exhaust step 2 in which unreacted reactive material and by-product gases generated by the reaction between the precursor thin film and the reactive material are exhausted from the reaction system. The precursor thin film formation step, exhaust step 1, metal thin film formation step, and exhaust step 2 constitute one cycle, which is preferably repeatedly performed. This is because this facilitates the formation of a continuous, high-purity metal thin film with a high film formation rate, a uniform film thickness, and minimal residual carbon and oxygen. The thin film manufacturing method of the present disclosure sequentially performs the precursor thin film formation step, exhaust step 1, metal thin film formation step, and exhaust step 2, forming the thin film through a series of operations, which constitutes one cycle. By repeating this cycle, a cobalt metal thin film having a desired thickness can be formed. For example, the above cycle may be performed only once to form a single layer of cobalt metal thin film, or the above cycle may be performed two or more times to form a cobalt metal thin film of a desired thickness.

[0085] The thickness of the cobalt metal thin film obtained per cycle is preferably 0.01 Å to 10 Å, more preferably 0.1 Å to 5 Å, and even more preferably 0.2 Å to 2 Å, because this makes it easier to form a continuous thin film of cobalt metal with a uniform thickness.

[0086] B5. Cobalt Metal Thin Film The cobalt metal thin film formed by the manufacturing method of the present disclosure contains 90 parts by mass or more of cobalt atoms per 100 parts by mass of the thin film. In the present disclosure, the content of cobalt atoms per 100 parts by mass of the thin film is preferably 96 parts by mass or more, more preferably 97 parts by mass or more, even more preferably 98 parts by mass or more, and even more preferably 99 parts by mass or more.

[0087] The cobalt metal thin film formed by the thin film manufacturing method of the present disclosure has excellent electrical properties such as low electrical resistivity, and is useful for various semiconductor devices. The electrical resistivity of the cobalt metal thin film, as measured by the four-terminal method, is preferably 50 μΩ cm or less, more preferably 30 μΩ cm or less, and even more preferably 15 μΩ cm or less.

[0088] Examples of the semiconductor device include field-effect transistors (FETs), nanosheet transistors, nanowire transistors, and complementary field-effect transistors (CFETs). The cobalt metal thin film formed by the thin-film manufacturing method of the present disclosure is particularly useful for semiconductor transistors having a semiconductor layer made of Si, SiGe, or Ge. However, it is expected that the thin-film may also be applicable to semiconductor transistors having a semiconductor layer made of a transition metal dichalcogenide such as MoS, MoSe, WS, or WSe. The cobalt metal thin film formed by the thin-film manufacturing method of the present disclosure can be used as a liner layer, capping layer, wiring via, or wiring layer in place of copper, on the top or bottom of the transistor, as a metal thin film for embedded power supplies, contacts, or wiring. The semiconductor device may also include other layers (e.g., an insulator layer, a conductor layer, a semiconductor layer, a buffer layer, or other intermediate layers).

[0089] C. Others The present invention also encompasses the following embodiments [1] to

[14] . [1] A method for producing a thin film by forming a cobalt metal thin film on a substrate by plasma enhanced ALD, comprising: a precursor thin film formation step of contacting the substrate with vapor of a thin film-forming raw material containing a compound represented by general formula (A) to form a precursor thin film; and a metal film formation step of reacting the precursor thin film with a plasmatized reactive material to form a cobalt metal thin film, the reactive material containing a reducing gas. [2] The method for producing a thin film according to [1], wherein the compound represented by general formula (A) is a compound represented by general formula (1). [3] In general formula (A) or general formula (1), R 1 and R 2is selected from a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. [4] The method for producing a thin film according to any of [1] to [3], wherein the reactive material contains hydrogen gas as the reducing gas. [5] The method for producing a thin film according to any of [1] to [4], wherein the reactive material contains a mixed gas of hydrogen gas and nitrogen gas. [6] The method for producing a thin film according to any of [1] to [5], further comprising an exhaust step 1 between the precursor thin film formation step and the metal film formation step, in which undeposited vapor of the thin film-forming raw material is exhausted from the reaction system. [7] The method for producing a thin film according to any of [1] to [6], further comprising an exhaust step 2 after the metal film formation step, in which unreacted reactive material and by-product gases generated by the reaction of the precursor thin film with the reactive material are exhausted from the reaction system, and one cycle consisting of the precursor thin film formation step, the exhaust step 1, the metal film formation step, and the exhaust step 2 is repeatedly carried out. [8] A thin film forming material for atomic layer deposition, containing a compound represented by the general formula (A). [9] The thin film forming material for atomic layer deposition according to [8], wherein the compound represented by the general formula (A) is a compound represented by the general formula (1).

[10] In the general formula (A) or the general formula (1), R 1 , R 2 , R 3 and R 4

[11] In the general formula (A) or (1), R 1 and R 2 are both selected from the combination of an ethyl group, a methyl group and an isopropyl group, a methyl group and an ethyl group, or a hydrogen atom and a tert-butyl group; R 3 and R 4

[12] The thin film forming material for atomic layer deposition according to any of [8] to

[11] , wherein the compound represented by general formula (A) or general formula (1) contains at least one of the following compounds:

[13] The thin film forming material for atomic layer deposition according to any one of [8] to

[12] , wherein the total content of impurity metal atoms is 1 ppt or more and 10 ppm or less.

[14] The thin film forming material for atomic layer deposition according to any one of [8] to

[13] , wherein the atomic layer deposition is a plasma enhanced ALD method.

[0090] The present invention is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and that provides similar effects is included within the technical scope of the present invention.

[0091] The present invention will be described in more detail below using examples, etc. However, the present invention is not limited to the following examples, etc.

[0092] (1) Thin Film-Forming Raw Materials The following compounds were used as thin film-forming raw materials, and cobalt metal thin films were formed and evaluated as shown in Examples 1 to 4 and Comparative Example 1 below.

[0093]

[0094] Example 1: Using Compound No. 23 as the compound represented by the general formula (1) above, and the ALD apparatus shown in FIG. 1 , a cobalt metal thin film was formed on a substrate S under the following conditions. The composition of the resulting thin film was analyzed using X-ray diffraction and X-ray photoelectron spectroscopy. The thin film was found to be a cobalt metal thin film, with a residual carbon content of less than 1 atom% and a residual oxygen content of less than 1 atom%. Furthermore, the thickness of the thin film was measured using X-ray reflectivity. The thin film formed on the substrate S was a smooth film with a thickness of 1014 Å, and the film thickness obtained per cycle was 1.01 Å. Generally, a film thickness of 0.5 Å or greater per cycle indicates a high film formation rate. The X-ray reflectivity was measured using an apparatus manufactured by Rigaku Corporation. Furthermore, the electrical resistivity (μΩ·cm) of the resulting cobalt metal thin film was measured using a four-terminal method and found to be 39 μΩ·cm. For the four-terminal method, an apparatus manufactured by Nitto Seiko Analytech Co., Ltd. (product name: Loresta-GX MCP-T700) was used.

[0095] (Conditions) Reaction temperature (substrate temperature): 200°C (Steps 1 to 4) Reactive material: mixed gas of hydrogen and nitrogen (hydrogen flow rate: nitrogen flow rate = 100cc: 30cc) Substrate: silicon oxide substrate

[0096] (Steps) A series of steps consisting of steps 1 to 4 below constitute one cycle, and were repeated 1,000 times. Step 1: The thin film-forming raw material was vaporized under conditions of a source container 101 heating temperature of 90°C and an internal pressure of the source container 101 of 100 Pa. The resulting vapor was introduced into the film-forming chamber 100, and the compound (No. 23) represented by general formula (1) contained in the thin film-forming raw material M was deposited on the surface of the substrate S at a system pressure of 100 Pa for 8 seconds to form a precursor thin film. Step 2: An argon purge was performed for 30 seconds to evacuate the vapor of the thin film-forming raw material M that had not been adsorbed and had not reacted from the system. Step 3: A reactive material was introduced into the film-forming chamber 100, and high-frequency power (50 W) at a frequency of 13.56 MHz was applied to the reactive material using a radio-frequency (RF) power supply 105 to generate plasma in the reactive material. This plasma was then reacted with the precursor thin film formed in step 1 at a system pressure of 100 Pa for 20 seconds to form a cobalt metal thin film. Step 4: By purging with argon for 15 seconds, unreacted plasma-converted reactive material and by-product gases generated by the reaction between the precursor thin film and the plasma-converted reactive material in step 3 are exhausted from the system.

[0097] Example 2 Using Compound No. 23 as the compound represented by the general formula (1) above and the ALD apparatus shown in FIG. 1 , a cobalt metal thin film was formed on a substrate S under the following conditions. The composition of the resulting thin film was analyzed using X-ray diffraction and X-ray photoelectron spectroscopy. The thin film was found to be a cobalt metal thin film, with a residual carbon content of less than 1 atom % and a residual oxygen content of less than 1 atom %. Furthermore, the thickness of the thin film was measured using X-ray reflectivity. The thin film formed on the substrate S was found to be a smooth film with a thickness of 352 Å, and the film thickness obtained per cycle was 0.35 Å. Furthermore, the electrical resistivity of the resulting cobalt metal thin film was measured using a four-terminal method and found to be 14 μΩ cm.

[0098] (Conditions) Reaction temperature (substrate temperature): 150°C (Steps 1 to 4) Reactive material: mixed gas of hydrogen and nitrogen (hydrogen flow rate: nitrogen flow rate = 100cc: 30cc) Substrate: silicon oxide substrate

[0099] (Steps) A series of steps 1 to 4 below constitute one cycle, and after 1,000 cycles, a one-hour annealing step was performed in an argon and hydrogen mixed gas environment (argon flow rate: hydrogen flow rate = 1,000 cc: 500 cc) at a substrate temperature of 300°C and a system pressure of 100 Pa. Step 1: Thin film-forming raw material M was vaporized under conditions of a source container 101 heating temperature of 90°C and a source container 101 internal pressure of 100 Pa, and the resulting vapor was introduced into the film-forming chamber 100. Compound (No. 23) represented by general formula (1) contained in the thin film-forming raw material M was deposited on the surface of the substrate S for 16 seconds at a system pressure of 100 Pa to form a precursor thin film. Step 2: Unadsorbed, unreacted thin film-forming raw material M vapor was evacuated from the system by argon purging for 30 seconds. Step 3: The reactive material is introduced into the film formation chamber 100, and a radio frequency (RF) power supply 105 is used to apply radio frequency power (50 W) at a frequency of 13.56 MHz to the reactive material to generate plasma in the reactive material, which is then reacted with the precursor thin film formed in step 1 for 40 seconds at a system pressure of 100 Pa to form a cobalt metal thin film. Step 4: An argon purge is performed for 15 seconds to exhaust from the system the unreacted plasma-converted reactive material and by-product gases generated by the reaction between the precursor thin film and the plasma-converted reactive material in step 3.

[0100] Example 3 Using Compound No. 23 as the compound represented by the general formula (1) above, and the ALD apparatus shown in FIG. 1 , a cobalt metal thin film was formed on a substrate S under the following conditions. The composition of the obtained thin film was analyzed using X-ray diffraction and X-ray photoelectron spectroscopy. The thin film was found to be a cobalt metal thin film, with a residual carbon content of 9 atom % and a residual oxygen content of 1 atom %. Furthermore, the thickness of the thin film was measured using X-ray reflectivity. The thin film formed on the substrate S was found to be a smooth film with a thickness of 152 Å, and the film thickness obtained per cycle was 0.15 Å. Furthermore, the electrical resistivity of the obtained cobalt metal thin film was measured using a four-terminal method, and was found to be 25 μΩ cm.

[0101] (Conditions) Reaction temperature (substrate temperature): 150°C (Steps 1 to 4) Reactive material: hydrogen gas Substrate: silicon oxide substrate

[0102] (Steps) A series of steps 1 to 4 below constitute one cycle, and after 1,000 cycles, a one-hour annealing step was performed in an argon and hydrogen mixed gas environment (argon flow rate: hydrogen flow rate = 1,000 cc: 500 cc) at a substrate temperature of 300°C and a system pressure of 100 Pa. Step 1: Thin film-forming raw material M was vaporized under conditions of a source container 101 heating temperature of 90°C and a source container 101 internal pressure of 100 Pa, and the resulting vapor was introduced into the film-forming chamber 100. Compound (No. 23) represented by general formula (1) contained in the thin film-forming raw material M was deposited on the surface of the substrate S for 10 seconds at a system pressure of 100 Pa to form a precursor thin film. Step 2: Unadsorbed, unreacted thin film-forming raw material M vapor was evacuated from the system by argon purging for 30 seconds. Step 3: The reactive material is introduced into the film formation chamber 100, and a radio frequency (RF) power supply 105 is used to apply radio frequency power (50 W) at a frequency of 13.56 MHz to the reactive material to generate plasma in the reactive material, which is then reacted with the precursor thin film formed in step 1 for 20 seconds at a system pressure of 100 Pa to form a cobalt metal thin film. Step 4: An argon purge is performed for 15 seconds to exhaust from the system the unreacted plasma-converted reactive material and by-product gases generated by the reaction between the precursor thin film and the plasma-converted reactive material in step 3.

[0103] Example 4 Using Compound No. 37 as the compound represented by the general formula (1) above, and the ALD apparatus shown in FIG. 1 , a cobalt metal thin film was formed on a substrate S under the following conditions. The composition of the resulting thin film was analyzed using X-ray diffraction and X-ray photoelectron spectroscopy. The thin film was found to be a cobalt metal thin film, with a residual carbon content of less than 1 atom % and a residual oxygen content of less than 1 atom %. Furthermore, the thickness of the thin film was measured using X-ray reflectivity. The thin film formed on the substrate S was found to be a smooth film with a thickness of 1150 Å, and the film thickness obtained per cycle was 1.15 Å. Furthermore, the electrical resistivity of the resulting cobalt metal thin film was measured using a four-terminal method and found to be 20 μΩ cm.

[0104] (Conditions) Reaction temperature (substrate temperature): 250°C (Steps 1 to 4) Reactive material: mixed gas of hydrogen and nitrogen Substrate: silicon oxide substrate

[0105] (Steps) A series of steps consisting of the following steps 1 to 4 was repeated 1,000 times, with one cycle consisting of these steps. Step 1: Thin film-forming raw material M was vaporized under conditions of a source container 101 heating temperature of 90°C and an internal pressure of the source container 101 of 100 Pa. The resulting vapor was introduced into the film-forming chamber 100, and the compound (No. 37) represented by general formula (1) contained in the thin film-forming raw material M was deposited on the surface of the substrate S for 16 seconds at a system pressure of 100 Pa to form a precursor thin film. Step 2: An argon purge was performed for 30 seconds to evacuate the unadsorbed, unreacted vapor of thin film-forming raw material M from the system. Step 3: A reactive material was introduced into the film-forming chamber 100, and high-frequency power (50 W) at a frequency of 13.56 MHz was applied to the reactive material using a radio-frequency (RF) power supply 105 to generate plasma from the reactive material. This plasma was then reacted with the precursor thin film formed in step 1 for 40 seconds at a system pressure of 100 Pa to form a cobalt metal thin film. Step 4: By purging with argon for 15 seconds, unreacted plasma-converted reactive material and by-product gases generated by the reaction between the precursor thin film and the plasma-converted reactive material in step 3 are exhausted from the system.

[0106] Comparative Example 1 Using the comparative compound 1 (cobalt bis(N,N'-di-tert-butylacetamidinate)) as a comparative compound for the compound represented by the general formula (1), a thin film was formed on a substrate S under the following conditions using the ALD apparatus shown in FIG. 1 . The composition of the obtained thin film was analyzed using X-ray diffraction and X-ray photoelectron spectroscopy. It was found to be a cobalt oxide thin film, with a residual carbon content of 20 atom % and a residual oxygen content of less than 1 atom %. Furthermore, when the film thickness of the thin film was measured using X-ray reflectivity, it was found to be a smooth film with a thickness of 600 Å, and the film thickness obtained per cycle was 0.60 Å. Furthermore, the electrical resistivity of the obtained cobalt oxide thin film was measured using a four-terminal method and was found to be 1,000 μΩ cm.

[0107] (Conditions) Reaction temperature (substrate temperature): 150°C (Steps 1 to 4) Reactive material: hydrogen gas Substrate: silicon oxide substrate

[0108] (Steps) A series of steps consisting of steps 1 to 4 below constitute one cycle, and after 1,000 cycles were repeated, a one-hour annealing process was carried out in an argon and hydrogen mixed gas environment (argon flow rate: hydrogen flow rate = 1,000 cc: 500 cc) at a gas temperature of 300°C and a system pressure of 100 Pa. Step 1: The thin film-forming raw material was vaporized under conditions of a source container 101 heating temperature of 80°C and a source container 101 internal pressure of 100 Pa, and the resulting vapor was introduced into the film-forming chamber 100. Comparative compound 1 contained in the thin film-forming raw material was deposited on the surface of the substrate S for 10 seconds at a system pressure of 100 Pa to form a precursor thin film. Step 2: An argon purge was used for 30 seconds to evacuate unadsorbed, unreacted thin film-forming raw material vapor from the system. Step 3: The reactive material is introduced into the film formation chamber 100, and a radio frequency (RF) power supply 105 is used to apply radio frequency power (50 W) at a frequency of 13.56 MHz to the reactive material to generate plasma in the reactive material, which is then reacted with the precursor thin film formed in step 1 for 20 seconds at a system pressure of 100 Pa to form a thin film. Step 4: An argon purge is performed for 15 seconds to exhaust from the system the unreacted plasma-converted reactive material and by-product gases generated by the reaction between the precursor thin film in step 3 and the plasma-converted reactive material.

[0109]

[0110] From the above results, it was confirmed that the thin film manufacturing method of the present disclosure can form a cobalt metal thin film with low electrical resistivity.

[0111] REFERENCE SIGNS LIST 100 Film formation chamber 101 Raw material container 102 Vaporization chamber 103 Heater 104 Mass flow controller (MFC) 105 Radio frequency (RF) power supply 106 RF matching system 107 Vacuum pump 108 Automatic pressure controller 109 Cold trap 201 Carrier gas 202 Reactive material 203 Exhaust 204 Purge gas M Raw material for thin film formation S Substrate

Claims

1. A method for producing a thin film by forming a cobalt metal thin film on a substrate by plasma enhanced ALD, comprising: a precursor thin film formation step of contacting the substrate with vapor of a thin film-forming raw material containing a compound represented by the following general formula (A) to form a precursor thin film; and a metal film formation step of reacting the precursor thin film with a plasmatized reactive material to form a cobalt metal thin film, wherein the reactive material contains a reducing gas. (In the formula, R 1 ~R 6 each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms, and m represents an integer of 0 to .

2. The method for producing a thin film according to claim 1, wherein the compound represented by general formula (A) is a compound represented by the following general formula (1): (In the formula, R 1 and R 2 each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms; R 3 and R 4 each independently represents a linear or branched alkyl group having 1 to 5 carbon atoms.

3. In the general formula (1), R 1 and R 2 The method for producing a thin film according to claim 2, wherein is selected from a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms.

4. The method for producing a thin film according to claim 2, wherein said reactive material contains hydrogen gas as said reducing gas.

5. The method for producing a thin film according to claim 2, wherein the reactive material comprises a mixture of hydrogen gas and nitrogen gas.

6. A method for producing a thin film according to any one of claims 2 to 5, further comprising an exhaust step 1 between the precursor thin film formation step and the metal film formation step, in which undeposited vapor of the thin film forming raw material is exhausted from the reaction system.

7. The method for producing a thin film according to claim 6, further comprising an exhaust step 2 for exhausting from the reaction system unreacted reactive material and by-product gases generated by the reaction between the precursor thin film and the reactive material after the metal film formation step, wherein one cycle of the precursor thin film formation step, exhaust step 1, metal film formation step and exhaust step 2 is repeatedly carried out.

8. A thin film forming material for atomic layer deposition, comprising a compound represented by the following general formula (A): (In the formula, R 1 ~R 6 each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms, and m represents an integer of 0 to 5.

9. The thin film forming material for atomic layer deposition according to claim 8, wherein the compound represented by the following general formula (A) is a compound represented by the following general formula (1): (In the formula, R 1 and R 2 each independently represents a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms; R 3 and R 4 each independently represents a linear or branched alkyl group having 1 to 5 carbon atoms.

10. In the general formula (1), R 1 , R 2 , R 3 and R 4 10. The thin film forming material for atomic layer deposition according to claim 9, wherein the total number of carbon atoms is 6 or more and 7 or less.

11. In the general formula (1), R 1 and R 2 are both selected from the combination of an ethyl group, a methyl group and an isopropyl group, a methyl group and an ethyl group, or a hydrogen atom and a tert-butyl group; R 3 and R 4 The thin film forming material for atomic layer deposition according to claim 9 , wherein both of are selected from a methyl group or a combination of a methyl group and an ethyl group.

12. The thin film forming material for atomic layer deposition according to claim 9, wherein the compound represented by general formula (1) includes at least one of the following compounds:

13. The raw material for forming a thin film by atomic layer deposition according to claim 9, wherein the total content of impurity metal atoms in the raw material for forming a thin film by atomic layer deposition is 1 ppt or more and 10 ppm or less.

14. The thin film forming material for atomic layer deposition according to claim 9, wherein the atomic layer deposition method is a plasma enhanced ALD method.

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