Starting material for thin film formation, thin film, production method for thin film, and compound

Abstract

The present disclosure relates to a starting material for thin film formation that contains a compound represented by general formula (1), a production method for a thin film, and a compound represented by general formula (3).　(1) M(L)n (In general formula (1), M represents a rare earth element that is not lanthanum, L represents an amidinate ligand represented by formula (2), and n represents an integer from 2 to 4, inclusive.) (In general formula (2), R1 and R2 each independently represent a C1–8 alkyl group, R3 represents a hydrogen atom or a C1–5 alkyl group, and * represents the bonding site of M, provided that R1 and R2 are different groups.) (In general formula (3), M represents a rare earth element that is not lanthanum, R4 and R5 each independently represent a C1–8 alkyl group, and R6 represents a hydrogen atom or a C1–5 alkyl group, provided that R4 and R5 are different groups, and the total number of carbon atoms in the groups represented by R4 and R5 is 7–15.)

Description

Thin film forming material, thin film, method for producing thin film and compound

[0001] The present disclosure relates to a compound having a rare earth element and a specific structure, a thin film-forming material containing the compound, a thin film produced using the thin film-forming material, and a method for producing a thin film.

[0002] Thin films formed from rare earth element oxides are expected to be used as dielectrics in microelectronic applications. For example, materials containing lanthanum atoms are used as materials for manufacturing DRAM gates, Logic transistors, etc.

[0003] Examples of methods for producing the thin film include sputtering, ion plating, MOD (Metal Organic Decomposition) methods such as coating pyrolysis and sol-gel methods, and chemical vapor deposition. Among these, chemical vapor deposition methods including chemical vapor deposition (hereinafter sometimes referred to as "CVD (Chemical Vapor Deposition) method") and atomic layer deposition (hereinafter sometimes referred to as "ALD (Atomic Layer Deposition) method") are the most suitable production processes because they have many advantages such as excellent composition controllability and step coverage, suitability for mass production, and the ability to achieve hybrid integration.

[0004] A wide variety of raw materials have been reported as sources of rare earth elements used in chemical vapor deposition. For example, Patent Document 1 discloses a lanthanoid complex in which an amidinate ligand and a cyclopentadienyl group are coordinated, Patent Document 2 discloses a lanthanum compound in which a ketoimine ligand and an alkoxy group are coordinated, and Patent Documents 3 to 5 disclose lanthanum amidinate compounds. Patent Document 6 discloses a complex containing scandium or yttrium and an amidinate ligand in its structure.

[0005] International Publication No. 2022 / 106508 Japanese Patent Publication No. 2012-153688 Chinese Patent Application Publication No. 114192136 US Patent Application Publication No. 2013 / 0078454 Chinese Patent Application Publication No. 113582879 Korean Patent Registration No. 10-2614467

[0006] However, when compounds containing rare earth elements other than lanthanum are used as precursors, conventional compounds have high melting points or poor thermal stability or volatility, making them difficult to apply to chemical vapor deposition, particularly atomic layer deposition. High-melting-point precursors, in particular, have lower vaporization efficiency than liquid materials, and require complex-shaped containers for solid materials to ensure stable vapor supply. Furthermore, valves and piping are prone to clogging, making it difficult to efficiently produce thin films containing rare earth elements (hereinafter sometimes referred to as "rare earth-containing thin films").

[0007] Therefore, an object of the present disclosure is to provide a thin film-forming material that has a low melting point, excellent thermal stability and volatility, and that can be used to produce rare earth element-containing thin films with high productivity, and a method for producing thin films using the same.

[0008] As a result of intensive research to solve the above-mentioned problems, the present inventors have found that a compound having a specific structure with a rare earth element other than lanthanum can solve the above-mentioned problems, and have thus completed the present disclosure.

[0009] That is, the present disclosure provides a thin film-forming material containing a compound represented by the following general formula (1):

[0010] M (L) ｎ (1)

[0011] In the above general formula (1), M represents a rare earth element other than lanthanum, L represents an amidinate ligand represented by the following formula (2), and n represents an integer of 2 to 4.

[0012]

[0013] In the above general formula (2), R １ and R ２ each independently represents an alkyl group having 1 to 8 carbon atoms; R ３ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and * (asterisk) represents the bonding position with M. １ and R ２ are different groups.

[0014] Another embodiment of the present disclosure is a thin film produced using the thin film-forming raw material.

[0015] Yet another embodiment of the present disclosure is a method for producing a thin film, which comprises using the thin film-forming material described above to form a thin film containing a rare earth element.

[0016] Yet another embodiment of the present disclosure is a rare earth element compound represented by the following general formula (3):

[0017]

[0018] In the general formula (3), M represents a rare earth element other than lanthanum, and R ４ and R ５ each independently represents an alkyl group having 1 to 8 carbon atoms; R ６ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. ４ and R ５ are different groups, and R ４ and R ５ The total number of carbon atoms in the group represented by the formula (I) is 7 or more and 15 or less.

[0019] The compound represented by the following general formula (4) has the same meaning as the rare earth element compound represented by the above general formula (3).

[0020]

[0021] (In general formula (4), M, R ４ , R ５ and R ６ represents the same as that described in the above general formula (3).

[0022] The compounds disclosed in this specification can provide a thin film-forming material that has a low melting point, excellent thermal stability, and volatility, and that can be used to produce rare earth element-containing thin films with high productivity, as well as a thin film production method using the same.

[0023] Fig. 1 is a schematic diagram showing an example of an ALD apparatus used in a method for producing a thin film according to an embodiment of the present disclosure. Fig. 2 is a schematic diagram showing another example of an ALD apparatus used in a method for producing a thin film according to an embodiment of the present disclosure. Fig. 3 is a schematic diagram showing another example of an ALD apparatus used in a method for producing a thin film according to an embodiment of the present disclosure. Fig. 4 is a schematic diagram showing another example of an ALD apparatus used in a method for producing a thin film according to an embodiment of the present disclosure.

[0024] A. Thin Film-Forming Raw Material The thin film-forming raw material of the present disclosure will be described.

[0025] A1. Compound represented by general formula (1) The thin film-forming material of the present disclosure contains a compound represented by the following general formula (1).

[0026] M (L) ｎ (1)

[0027] In general formula (1), M represents a rare earth element other than lanthanum, L represents an amidinate ligand represented by the following general formula (2), and n represents an integer of 2 to 4.

[0028]

[0029] In the above general formula (2), R １ and R ２ each independently represents an alkyl group having 1 to 8 carbon atoms; R ３ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and * represents the bonding position with M. １ and R ２ are different groups.

[0030] Examples of rare earth elements other than lanthanum represented by M include scandium (Sc), yttrium (Y), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).

[0031] The R in the general formula (2) １and R ２ each independently represents an alkyl group having 1 to 8 carbon atoms, ３ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. １ and R ２ are different groups.

[0032] The above R １ and R ２ Examples of the alkyl group having 1 to 8 carbon atoms represented by the formula (I) include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a sec-pentyl group, a 3-pentyl group, a neopentyl group, an n-hexyl group, an isohexyl group, a sec-hexyl group, a tert-hexyl group, an n-heptyl group, an isoheptyl group, a sec-heptyl group, a tert-heptyl group, an n-octyl group, an isooctyl group, a sec-heptyl group, a tert-octyl group, and a 2-ethylhexyl group. Here, sec-pentyl refers to 2-pentyl.

[0033] In addition, in the present disclosure, from the viewpoint of having a low melting point, excellent thermal stability and volatility, and being able to produce a rare earth element-containing thin film with good productivity, １ and R ２ The total number of carbon atoms in the group represented by the formula (I) is more preferably 7 or more and 15 or less, even more preferably 7 or more and 12 or less, even more preferably 7 or more and 10 or less, and particularly preferably 7 or more and 9 or less.

[0034] The above R ３ The alkyl group having 1 to 5 carbon atoms represented by the formula (I) is １ Among alkyl groups having 1 to 8 carbon atoms, represented by the following formula, groups having a predetermined number of carbon atoms can be mentioned.

[0035] From the viewpoint of low melting point, excellent thermal stability and volatility, and enabling production of a rare earth element-containing thin film with good productivity, the above-mentioned M is more preferably Y, Pr, Nd, Pm, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu, further preferably Y, Yb, Er, and Lu, particularly preferably Y, Yb, and Lu, and most preferably Y.

[0036] From the viewpoint of low melting point, excellent thermal stability and volatility, and enabling the production of rare earth element-containing thin films with good productivity, １ and R ２ is preferably selected from alkyl groups having 3 to 6 carbon atoms, more preferably from branched alkyl groups having 3 to 6 carbon atoms, and １ and R ２ and R is an isopropyl group. １ and R ２ It is particularly preferred that one of R is selected from a sec-butyl group or a sec-pentyl group, and the other is an isopropyl group. １ and R ２ It is most preferred that one of these groups is a sec-pentyl group and the other is an isopropyl group.

[0037] From the viewpoint of low melting point, excellent thermal stability and volatility, and enabling the production of rare earth element-containing thin films with good productivity, ３ As the alkyl group, a hydrogen atom and an alkyl group having 1 to 3 carbon atoms are preferred, a hydrogen atom and a methyl group are more preferred, and a hydrogen atom is particularly preferred.

[0038] n represents an integer of 2 to 4, and n is preferably 3.

[0039] The compound represented by the general formula (1) may be in the form of a solid or liquid at 25°C under normal pressure. However, in order to ensure transportability in the piping of a thin-film manufacturing apparatus, it preferably has a melting point of 100°C or less under normal pressure, and more preferably is a liquid at 25°C under normal pressure.

[0040] Examples of the ligand represented by the general formula (2) constituting the compound represented by the general formula (1) used in the thin-film-forming material of the present disclosure include ligands represented by Nos. 1 to 132 in Tables 1 and 2 below, but the thin-film-forming material of the present disclosure is not limited to the compound represented by the general formula (1) having these ligands. In the following chemical formulas, "Me" represents a methyl group, "Et" represents an ethyl group, "iPr" represents an isopropyl group, "iBu" represents an isobutyl group, "sBu" represents a sec-butyl group, "tBu" represents a tert-butyl group, [nPe] represents an n-pentyl group, [iPe] represents an isopentyl group, "sPe" represents a sec-pentyl group, and "3Pe" represents a 3-pentyl group.

[0041]

[0042]

[0043] In the present disclosure, from the viewpoint of being able to produce a rare earth element-containing thin film with a low melting point, excellent thermal stability, and volatility, and with good productivity, the thin film-forming material of the present disclosure preferably contains a compound containing an amidinate ligand in its structure, such as those represented by Nos. 22 to 66 and Nos. 88 to 132, and also preferably contains compounds represented by Nos. 32 to 34, 36 to 38, 46, 47, 49 to 52, 54 to 56, 58 to 60, 64 to 66, 98 to 100, 102 to 104, 112, 113, and 115 to 120. It is more preferable to contain a compound containing an amidinate ligand represented by No. 118, No. 120 to No. 122, No. 124 to No. 126, or No. 130 to No. 132 in its structure, and it is even more preferable to contain a compound containing an amidinate ligand represented by No. 33, No. 37, No. 38, No. 99, No. 103, or No. 104 in its structure, and it is particularly preferable to contain a compound containing an amidinate ligand represented by No. 33, No. 37, No. 38, No. 103, or No. 104 in its structure, and it is especially preferable to contain a compound containing an amidinate ligand represented by No. 33, No. 37, or No. 103 in its structure, and it is particularly preferable to contain a compound containing an amidinate ligand represented by No. 33, No. 37, or No. 103 in its structure, and It is most preferred to contain a compound containing an amidinate ligand represented by 37 in its structure.

[0044] In a preferred embodiment, the rare earth element of the compound containing an amidinate ligand in its structure, represented by No. 33, No. 37, No. 38, No. 99, No. 103, or No. 104, is preferably Y, Yb, or Lu, and more preferably Y. In this case, n in general formula (1) is preferably 3. In a more preferred embodiment, the rare earth element of the compound containing an amidinate ligand in its structure, represented by No. 33, No. 37, or No. 103, is preferably Y, Yb, or Lu, and more preferably Y. In this case, n in general formula (1) is preferably 3. In a further preferred embodiment, the rare earth element of the compound containing an amidinate ligand in its structure, represented by No. 33 or No. 37, is preferably Y, Yb, or Lu, and more preferably Y. In this case, n in general formula (1) is preferably 3. In a particularly preferred embodiment, the rare earth element of the compound containing an amidinate ligand in its structure, represented by No. 37, is preferably Y, Yb, or Lu, and more preferably Y. In this case, n in general formula (1) is preferably 3.

[0045] The compound represented by the general formula (1) is not particularly limited by its production method and can be produced by a well-known synthesis method. For example, in the presence or absence of a solvent, M[N(SiMe ３ ) ２ ] ３ and a compound having a ligand of the corresponding structure, and stirring the mixture to cause a reaction. M represents a rare earth element excluding lanthanum.

[0046] A2. Rare earth element compound represented by general formula (3) In the present disclosure, from the viewpoint of being able to produce a rare earth element-containing thin film with a low melting point, excellent thermal stability, and volatility, and with good productivity, it is preferable that the thin film-forming raw material contains a rare earth element compound represented by the following general formula (3). The thin film-forming raw material of the present disclosure may contain at least one rare earth element compound represented by the following general formula (3), and may contain two or more types.

[0047]

[0048] In the general formula (3), M represents a rare earth element other than lanthanum, and R ４ and R ５ each independently represents an alkyl group having 1 to 8 carbon atoms; R ６ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. ４ and R ５ are different groups, and the R ４ and R ５ The total number of carbon atoms in the group represented by the formula (I) is 7 or more and 15 or less.

[0049] The above R ４ and R ５ The alkyl group having 1 to 8 carbon atoms represented by the formula (I) is the same as the above-mentioned R １ and R ６ The alkyl group having 1 to 5 carbon atoms represented by the formula (I) is １ Examples of the alkyl group include groups having a predetermined number of carbon atoms in the alkyl group having 1 to 8 carbon atoms, represented by the following formula:

[0050] In the present disclosure, the above R ４ and R ５ is preferably selected from alkyl groups having 3 to 6 carbon atoms, more preferably from branched alkyl groups having 3 to 6 carbon atoms, and ４ and R ５ and R is an isopropyl group. ４ and R ５ It is particularly preferred that one of R is selected from a sec-butyl group or a sec-pentyl group, and the other is an isopropyl group. ４ and R ５ It is most preferred that one of these groups is a sec-pentyl group and the other is an isopropyl group.

[0051] In addition, in the present disclosure, from the viewpoint of having a low melting point, excellent thermal stability and volatility, and being able to produce a rare earth element-containing thin film with good productivity, ４ and R ５ The total number of carbon atoms in the group represented by the formula (I) is more preferably 7 or more and 12 or less, further preferably 7 or more and 10 or less, and particularly preferably 7 or more and 9 or less.

[0052] As the rare earth element compound represented by the above general formula (3), for example, preferred specific examples of the rare earth element compound in which M is yttrium include the following compounds No. 1 to No. 132, but the thin film-forming material of the present disclosure is not limited to these compounds.

[0053]

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078]

[0079]

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086]

[0087]

[0088]

[0089]

[0090]

[0091]

[0092]

[0093]

[0094]

[0095]

[0096]

[0097] Other preferred specific examples of the rare earth element compound represented by the above general formula (3) include compounds in which Y in the above Compounds No. 1 to No. 132 is replaced with another rare earth element.

[0098] The rare earth element compound represented by the general formula (3) is not particularly limited by its production method, and can be produced by applying a well-known synthesis method. For example, the rare earth element compound represented by the general formula (3) can be produced by reacting M[N(SiMe ３ ) ２ ] ３ It can be obtained by mixing and stirring with a compound having a ligand of the corresponding structure, reacting them, and then distilling them.

[0099] Regarding the above Compound No. 1 to Compound No. 132, R corresponding to general formula (3) ４ and R ５ From the viewpoint of low melting point, excellent thermal stability and volatility, and enabling production of a rare earth element-containing thin film with good productivity, both of them are preferably selected from alkyl groups having 3 to 6 carbon atoms, more preferably branched alkyl groups having 3 to 6 carbon atoms, and the R ４ and R ５ and R is an isopropyl group. ４ and R ５ It is particularly preferred that one of R is selected from a sec-butyl group or a sec-pentyl group, and the other is an isopropyl group. ４ and R ５ It is most preferred that one of these groups is a sec-pentyl group and the other is an isopropyl group.

[0100] The rare earth element compounds represented by the above general formula (3) have a low melting point, excellent thermal stability, and volatility, and from the viewpoint that rare earth element-containing thin films can be produced with good productivity, Compound No. 32 to Compound No. 34, Compound No. 36 to Compound No. 38, Compound No. 46, Compound No. 47, Compound No. 49 to Compound No. 52, Compound No. 54 to Compound No. 56, Compound No. 58 to Compound No. 60, Compound No. 64 to Compound No. 66, Compound No. 98 to Compound No. 100, Compound No. 102 to Compound No. 104, Compound No. 112, Compound No. 113, Compound No. 115 to Compound No. 118, Compound No. 120 to Compound No. 122, Compound No. 130, Compound No. 132 to Compound No. 134, Compound No. 136 to Compound No. 138, Compound No. 138 to Compound No. 139, Compound No. 139 to Compound No. 140, Compound No. 141 to Compound No. 142, Compound No. 143, Compound No. 144 to Compound No. 145, Compound No. 146, Compound No. 147, Compound No. 148 to Compound No. 149, Compound No. 149 to Compound No. 150, Compound No. 151 to Compound No. 152, Compound No. 153 to Compound No. 154, Compound No. 155 to Compound No. 156, Compound No. 157 to Compound No. 158, Compound No. 159 to Compound No. 159, Compound No. 159 to Compound No. 160, Compound No. 161 to Compound No. 162, Compound No. 163, Compound No. Compound No. 124 to Compound No. 126, and Compound No. 130 to Compound No. 132 are preferred, Compound No. 33, Compound No. 37, Compound No. 38, Compound No. 99, Compound No. 103, and Compound No. 104 are more preferred, Compound No. 33, Compound No. 37, Compound No. 38, Compound No. 103, and Compound No. 104 are even more preferred, Compound No. 33, Compound No. 37, and Compound No. 103 are even more preferred, Compound No. 33 and Compound No. 37 are particularly preferred, and Compound No. 37 is most preferred.

[0101] A3. Other Components The thin film-forming material of the present disclosure may contain the compound represented by the general formula (1) as a precursor of a rare earth element-containing thin film, and may contain other components depending on the type of thin film to be formed. Examples of such other components include other precursors, organic solvents, nucleophilic reagents, etc.

[0102] (1) Other precursors: The other precursors are compounds containing metal atoms and / or metalloids and capable of forming a thin film, excluding the compound represented by the general formula (1). For example, the thin film-forming raw material of the present disclosure may contain, in addition to the compound represented by the general formula (1), a compound containing a desired metal and / or a compound containing a metalloid as another precursor.

[0103] In the present disclosure, the other precursor is not particularly limited, and may be a well-known precursor used as a raw material for forming a thin film using an ALD method, a CVD method, or the like. Examples of the other precursor include a reaction product of silicon or a metal with one or more compounds selected from the group consisting of compounds used as organic ligands, such as alcohol compounds, glycol compounds, β-diketone compounds, cyclopentadiene compounds, and organic amine compounds. Examples of the metal species of the precursor include lithium, sodium, potassium, magnesium, calcium, strontium, barium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, osmium, ruthenium, cobalt, rhodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, aluminum, gallium, indium, germanium, lead, antimony, bismuth, radium, lanthanum, and the above-mentioned rare earth elements.

[0104] 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.

[0105] 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.

[0106] Examples of the β-diketone compound used as the organic ligand for the other precursors include acetylacetone, hexane-2,4-dione, 5-methylhexane-2,4-dione, heptane-2,4-dione, 2-methylheptane-3,5-dione, 5-methylheptane-2,4-dione, 6-methylheptane-2,4-dione, 2,2-dimethylheptane-3,5-dione, 2,6-dimethylheptane-3,5-dione, 2,2,6-trimethylheptane-3,5-dione, 2,2,6,6-tetramethylheptane-3,5-dione, octane-2,4-dione, 2,2,6-trimethyloctane-3,5-dione, 2,6-dimethyloctane-3,5-dione, 2,9-dimethylnonane-4,6-dione, 2-methyl- Examples of suitable fluorine-substituted alkyl β-diketones include 6-ethyldecane-3,5-dione and 2,2-dimethyl-6-ethyldecane-3,5-dione; 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 include 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.

[0107] Examples of cyclopentadiene compounds used as organic ligands for the other precursors include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, propylcyclopentadiene, isopropylcyclopentadiene, butylcyclopentadiene, sec-butylcyclopentadiene, isobutylcyclopentadiene, tert-butylcyclopentadiene, dimethylcyclopentadiene, tetramethylcyclopentadiene, and pentamethylcyclopentadiene.

[0108] Examples of organic amine compounds that can be used as organic ligands for the other precursors include methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, tert-butylamine, isobutylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, ethylmethylamine, propylmethylamine, and isopropylmethylamine.

[0109] The other precursors described above are known in the art, and their production methods are also known. For example, when an alcohol compound is used as the organic ligand, the precursor can be produced by reacting the inorganic salt of the metal or a hydrate thereof described above with an alkali metal alkoxide of the alcohol compound. Examples of inorganic salts of metals or hydrates thereof include metal halides and nitrates. Examples of alkali metal alkoxides include sodium alkoxides, lithium alkoxides, and potassium alkoxides.

[0110] The multi-component ALD method described above includes a method in which each component of the thin film-forming raw material is supplied independently (hereinafter, sometimes referred to as a "single-source method"), and a method in which a multi-component raw material is mixed in advance to a desired composition and then vaporized and supplied as a mixed raw material (hereinafter, sometimes referred to as a "cocktail-source method"). When forming a thin film using the single-source method, from the viewpoint of facilitating the formation of a high-quality rare-earth element-containing thin film with little residual carbon, it is preferable that the other precursor be a compound whose thermal decomposition and / or oxidative decomposition behavior is similar to that of the compound represented by general formula (1). When forming a thin film using the cocktail-source method, a mixture of the compound represented by general formula (1) and the other precursor, or a mixed solution obtained by dissolving the mixture in the organic solvent, can be used as a thin film-forming raw material. However, it is preferable that the other precursor be a compound whose thermal decomposition and / or oxidative decomposition behavior is similar to that of the compound represented by general formula (1) and that does not undergo deterioration due to chemical reactions or the like when mixed.

[0111] In the present disclosure, from the viewpoint of facilitating the formation of a high-quality rare earth element-containing thin film with little residual carbon, the content of the 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 even more preferably 5 parts by mass or less, and most preferably 0 parts by mass, i.e., no other precursors are included, relative to 100 parts by mass of the thin film-forming raw material.

[0112] (2) Organic Solvent The thin film-forming material of the present disclosure may contain an organic solvent to dissolve the compound represented by the general formula (1) or the other precursors. The organic solvent is not particularly limited and may be any well-known organic solvent. Examples of the organic solvent include acetates such as ethyl acetate, butyl acetate, and methoxyethyl acetate; ethers such as tetrahydrofuran, tetrahydropyran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, dibutyl ether, and dioxane; ketones such as methyl butyl ketone, methyl isobutyl ketone, ethyl butyl ketone, dipropyl ketone, diisobutyl ketone, methyl amyl ketone, cyclohexanone, and methylcyclohexanone; hydrocarbons such as hexane, cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, heptane, octane, toluene, and xylene; hydrocarbons having a cyano group such as 1-cyanopropane, 1-cyanonobutane, 1-cyanohexane, cyanocyclohexane, cyanobenzene, 1,3-dicyanopropane, 1,4-dicyanobutane, 1,6-dicyanohexane, 1,4-dicyanocyclohexane, and 1,4-dicyanobenzene; pyridine, lutidine, and the like. These organic solvents can be used alone or in combination as a mixture of two or more depending on the solubility of the solute, the relationship between the temperature at which the organic solvent is used and its boiling point and flash point, and the like.

[0113] When the thin film-forming raw material of the present disclosure contains the organic solvent, from the viewpoint of facilitating the formation of a high-quality rare earth element-containing thin film with little residual carbon, the amount of organic solvent in the thin film-forming raw material is preferably adjusted so that the total amount of precursors in the thin film-forming raw material is 0.01 mol / L to 2.0 mol / L, and more preferably adjusted so that it is 0.05 mol / L to 1.0 mol / L.

[0114] Here, the total amount of precursors refers to the amount of the compound represented by the general formula (1) when the thin film-forming raw material does not contain any precursors other than the compound represented by the general formula (1). When the thin film-forming raw material contains other precursors in addition to the compound represented by the general formula (1), the total amount refers to the total amount of the compound represented by the general formula (1) and the other precursors.

[0115] (3) Nucleophilic Reagent The thin film-forming material of the present disclosure may contain a nucleophilic reagent, such as 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. Examples include 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.

[0116] When the thin film-forming raw material of the present disclosure contains the above-mentioned nucleophilic reagent, the content of the above-mentioned nucleophilic reagent is preferably in the range of 0.1 mol or more and 10 mol or less, more preferably in the range of 0.5 mol or more and 8 mol or less, and even more preferably in the range of 1 mol or more and 4 mol or less, relative to 1 mol of the total amount of the precursor.

[0117] (4) Impurities It is desirable that the thin film forming material of the present disclosure contains as few impurities as possible, such as impurity metal elements, impurity halogens, impurity organic substances, and the like, other than the components that form the desired thin film.

[0118] Examples of the impurity metal element include metal elements different from the constituent metal atoms of the compound represented by the general formula (1) and the other precursors. From the viewpoint of facilitating the formation of a high-quality rare earth element-containing thin film with little residual carbon, the content of the impurity metal element in the thin film-forming material of the present disclosure is preferably 1 ppm or less, more preferably 100 ppb or less, even more preferably 10 ppb or less, and most preferably 1 ppb or less.

[0119] Examples of the impurity halogen component include halogen compounds containing halogen atoms such as chlorine, fluorine, etc. From the viewpoint of facilitating the formation of a high-quality rare earth element-containing thin film with little residual carbon, the content of the impurity halogen component in the thin film-forming raw material of the present disclosure is preferably 100 ppm or less, more preferably 10 ppm or less, and even more preferably 1 ppm or less.

[0120] The impurity organic matter may be an organic component different from the organic component constituting the compound represented by the general formula (1). From the viewpoint of facilitating the formation of a high-quality rare earth element-containing thin film with little residual carbon, the content of the impurity organic components is preferably 500 ppm or less, more preferably 100 ppm or less, and even more preferably 50 ppm or less, in total, in the thin film-forming raw material of the present disclosure.

[0121] Furthermore, since moisture causes particle generation in the thin film-forming raw material and particle generation during thin film formation, it is desirable to remove moisture as much as possible from each component of the thin film-forming raw material before use. The moisture content of the compound represented by general formula (1), the other precursors, the organic solvent, the nucleophilic reagent, etc. is preferably 10 ppm or less, and more preferably 1 ppm or less.

[0122] In order to reduce or prevent particle contamination of the thin film to be formed, it is preferable to prevent particles from being contained in the thin film-forming raw material as much as possible. Specifically, in particle measurement of the thin film-forming raw material using a light scattering liquid-borne particle detector, it is preferable that the number of particles larger than 0.3 μm per mL of the thin film-forming raw material be 100 or less, and it is more preferable that the number of particles larger than 0.2 μm per mL of the thin film-forming raw material be 100 or less.

[0123] A4. Form of Thin Film Forming Raw Material The form of the thin film forming raw material of the present disclosure is selected as appropriate depending on the transportation and supply method, etc., employed in chemical vapor deposition methods including chemical vapor deposition and atomic layer deposition. The physical properties of the precursor compound represented by the general formula (1) above are suitable for chemical vapor deposition methods, and since it has an ALD window, the thin film forming raw material of the present disclosure is particularly useful as a thin film forming raw material for atomic layer deposition.

[0124] The transport / supply method includes a "gas transport method" and a "liquid transport method." The gas transport method includes, for example, a step of vaporizing the thin film-forming raw material of the present disclosure in a container filled with the thin film-forming raw material (hereinafter referred to as a "raw material container") by heating and / or reducing pressure to obtain a raw material gas, and a step of introducing the raw material gas, optionally together with a carrier gas such as argon, nitrogen, or helium, into a film-forming chamber in which a substrate is placed. The liquid transport method includes, for example, a step of transporting the thin film-forming raw material of the present disclosure in a liquid state to a vaporization chamber, a step of vaporizing the thin film-forming raw material in the vaporization chamber by heating and / or reducing pressure to obtain a raw material gas, and a step of introducing the raw material gas, optionally together with a carrier gas such as argon, nitrogen, or helium, into a film-forming chamber in which a substrate is placed.

[0125] In the case of the gas transport method, the compound represented by the general formula (1) can be used as the thin film-forming raw material. In the case of the liquid transport method, the compound represented by the general formula (1) or a solution obtained by dissolving the compound in the organic solvent can be used as the thin film-forming raw material. In addition, the thin film-forming raw material of the present disclosure can further contain other precursors, nucleophilic reagents, etc., as described above.

[0126] B. Thin Film Next, the thin film of the present disclosure will be described. The method for producing the thin film of the present disclosure is not limited as long as it is a method that can form a rare earth element-containing thin film using the thin film-forming material of the present disclosure, but for example, the method described below in "C. Thin Film Production Method" can be adopted.

[0127] Examples of thin films disclosed herein include metal films, oxide films, nitride films, carbide films, and sulfide films. However, the above-described thin films can be made into desired types of thin films by appropriately selecting other precursors, reactive gases, and manufacturing conditions of the thin film manufacturing method described below. Because the thin films disclosed herein have excellent electrical and optical properties, they can be widely used in the manufacture of, for example, electrode materials for memory elements such as DRAM elements, wiring materials used in semiconductor elements such as logic elements, diamagnetic films used in recording layers of hard disks, and catalyst materials for polymer electrolyte fuel cells. Furthermore, from the viewpoint of improving the electrical properties of the thin film, the carbon content in the thin film is preferably 1 atom% or less, more preferably 0.5 atom% or less, and even more preferably 0.1 atom% or less. Note that, in the case of analysis by X-ray photoelectron spectroscopy described below, the detection limit of the carbon content in the thin film is 0.1 atom%.

[0128] C. Thin Film Manufacturing Method Next, a thin film manufacturing method according to the present disclosure will be described. The thin film manufacturing method according to the present disclosure includes forming a rare earth element-containing thin film using the thin film-forming raw material described above. In the present disclosure, it is preferable to manufacture the thin film by a chemical vapor deposition method such as a CVD method or an ALD method, from the viewpoint of facilitating the formation of a high-quality rare earth element-containing thin film with little residual carbon.

[0129] The method for producing a rare earth element-containing thin film by a CVD method includes a step of forming a rare earth element-containing thin film by utilizing a surface reaction between the surface of a substrate and the compound represented by the general formula (1) in the source gas obtained by vaporizing the thin film-forming raw material, or a gas phase reaction between the compound represented by the general formula (1) in the source gas and a reactive gas.

[0130] The method for producing a rare earth element-containing thin film by the ALD method includes a precursor thin film formation step of introducing a source gas obtained by vaporizing the above-mentioned thin film-forming source material into a film formation chamber in which a substrate is placed, and depositing the compound represented by general formula (1) in the source gas on the surface of the substrate to form a precursor thin film, and a thin film formation step of introducing a reactive gas into the film formation chamber and reacting the precursor thin film with the reactive gas to form a rare earth element-containing thin film.

[0131] A well-known ALD apparatus can be used as an apparatus for producing a thin film using the thin film forming material of the present disclosure. Specific examples of the apparatus include an apparatus capable of supplying a precursor by bubbling as shown in FIGS. 1 and 3, and an apparatus having a vaporization chamber as shown in FIGS. 2 and 4. Another example is an apparatus capable of performing plasma treatment on a reactive gas as shown in FIGS. 3 and 4. It should be noted that the apparatus is not limited to the single-wafer apparatus equipped with a film formation chamber as shown in FIGS. 1 to 4, but an apparatus capable of simultaneously processing multiple wafers using a batch furnace can also be used. These can also be used as CVD apparatuses.

[0132] Hereinafter, the thin film manufacturing method will be described with reference to the drawings, taking the method of manufacturing a thin film by the ALD method as an example, and each step will be described. Note that the thin film forming raw materials used in the thin film manufacturing method of the present disclosure are the same as those described in the above section "A. Thin film forming raw materials," and therefore, description thereof will be omitted.

[0133] C1. Precursor Thin Film Formation Step In the precursor thin film formation step, a thin film-forming raw material is transported into source container 101 or vaporization chamber 102, and the thin film-forming raw material is vaporized to obtain a source gas. This source gas is supplied, together with carrier gases 110, 111 such as argon, nitrogen, or helium as necessary, into film formation chamber 100 in which a substrate is placed, and the compound represented by general formula (1) in the source gas is adsorbed and deposited on the surface of the substrate, thereby forming a precursor thin film.

[0134] (1) Transport of Thin Film Forming Raw Material Examples of a method for transporting the thin film forming raw material into the raw material container 101 or the vaporization chamber 102 include a gas transport method, a liquid transport method, a single source method, and a cocktail source method.

[0135] As shown in Figures 1 and 3, an example of the gas transport method is to heat and / or vaporize the thin film-forming raw material in a raw material container 101 using a heater 103, and introduce the resulting raw material gas into the film-forming chamber 100, optionally together with carrier gases 110, 111, such as argon, nitrogen, or helium. The concentration of the raw material gas when introduced together with the carrier gases 110, 111 preferably contains 90% by volume or more, more preferably 99% by volume or more, of the compound represented by general formula (1). As shown in Figures 2 and 4, an example of the liquid transport method is to transport the thin film-forming raw material in a liquid or solution state to a vaporization chamber 102, and then heat and / or vaporize the thin film-forming raw material in the vaporization chamber 102 to obtain a raw material gas, optionally together with carrier gases 110, 111, such as argon, nitrogen, or helium, and introduce the resulting raw material gas into the film-forming chamber 100.

[0136] The single-source method and the cocktail-source method are methods for transporting and supplying a thin-film-forming raw material containing multi-component precursors. The single-source method is a method in which precursors of each component are independently vaporized and supplied, while the cocktail-source method is a method in which a mixed raw material in which multi-component precursors are premixed is vaporized and supplied. The thin-film-forming raw material containing multi-component precursors may contain the nucleophilic reagents described above.

[0137] (2) Supply of Source Gas The thin film-forming raw material may be vaporized in the source container 101 or in the vaporization chamber 102. In either case, from the viewpoint of facilitating the formation of a high-quality rare earth element-containing thin film with little residual carbon, the thin film-forming raw material is preferably vaporized at a temperature of 0°C or higher and 300°C or lower, more preferably 0°C or higher and 250°C or lower, and even more preferably 30°C or higher and 200°C or lower.

[0138] When the thin film forming raw material is vaporized in the raw material container 101 or the vaporization chamber 102 to form a raw material gas, the pressure in the raw material container 101 or the vaporization chamber 102 is preferably in the range of 1 Pa or more and 10,000 Pa or less, more preferably in the range of 10 Pa or more and 5,000 Pa or less, and even more preferably in the range of 20 Pa or more and 1,000 Pa or less, from the viewpoint of achieving good vaporization of the thin film forming raw material.

[0139] When the source gas is introduced into the film formation chamber 100, the source gas can be introduced into the film formation chamber 100 together with carrier gases 110, 111 such as argon, nitrogen, or helium, as necessary. When the source gas is introduced into the film formation chamber 100 using the carrier gases 110, 111, the source gas preferably contains 90% by volume or more, and more preferably 99% by volume or more, of the gas of the compound represented by general formula (1).

[0140] (3) Formation of Precursor Thin Film: A method for forming a precursor thin film on a substrate placed in the deposition chamber 100 using a source gas includes, for example, a method utilizing a surface reaction between the compound represented by the general formula (1) in the source gas and the surface of the substrate. In the method utilizing the surface reaction, the source gas is brought into contact with the substrate, and the compound represented by the general formula (1) in the source gas is adsorbed and deposited on the substrate to form a precursor thin film. Heating the substrate or the deposition chamber 100 containing the substrate promotes the surface reaction, but increases damage to the substrate due to the high temperature. Therefore, the substrate or the deposition chamber 100 containing the substrate is preferably heated at a temperature ranging from room temperature to 500°C, more preferably from 100°C to 450°C, even more preferably from 130°C to 400°C, and particularly preferably from 150°C to 300°C.

[0141] The pressure (system pressure) inside the film formation chamber 100 in this step is preferably 1 Pa or more and 10,000 Pa or less, and more preferably 10 Pa or more and 1,000 Pa or less from the viewpoint of facilitating the production of a uniform precursor thin film.

[0142] In the present disclosure, the term "deposited" is a concept that includes chemical adsorption of the compound represented by the general formula (1) on the surface of a substrate, and the term "on a substrate" refers to the surface of a substrate or a rare earth element-containing thin film formed in a thin film formation step described below, i.e., the surface of a rare earth element-containing thin film grown by the thin film manufacturing method of the present disclosure.

[0143] Examples of materials for the substrate include silicon, ceramics such as silicon nitride, titanium nitride, tantalum nitride, titanium oxide, molybdenum oxide, zirconium oxide, hafnium oxide, and lanthanum oxide, glass, and metals such as metallic cobalt, metallic molybdenum, molybdenum sulfide, molybdenum selenide, tungsten sulfide, and tungsten selenide. Examples of the shape of the substrate include plate-like, spherical, fibrous, scale-like, flat, and disk-like plates, fibrous, cylindrical, prismatic, cylindrical, spiral, spherical, ring-like, and three-dimensional structures such as trench structures.

[0144] C2. Thin Film Formation Process In the thin film formation process, reactive gas 107 is introduced into the film formation chamber 100, and a rare earth element-containing thin film can be formed by utilizing a chemical reaction between the precursor thin film and reactive gas 107.

[0145] In this process, a thin film of an oxide, nitride, or metal can be formed by appropriately selecting the type of reactive gas 107. Examples of the reactive gas 107 to react with the precursor thin film include oxidizing gases such as oxygen, ozone, nitrogen dioxide, nitric oxide, water vapor, hydrogen peroxide, formic acid, acetic acid, and acetic anhydride; reducing gases such as hydrogen; organic amine compounds such as monoalkylamines, dialkylamines, trialkylamines, and alkylenediamines; nitriding gases such as hydrazine and ammonia; and sulfurizing gases such as sulfur, hydrogen sulfide, and dialkyl sulfides such as dimethyl sulfide, diethyl sulfide, and diisopropyl sulfide. These reactive gases 107 may be used alone or in combination of two or more. In the present disclosure, from the viewpoint of facilitating the formation of a high-quality rare-earth element-containing thin film with little residual carbon, the reactive gas 107 preferably contains at least one selected from the group consisting of hydrogen, oxygen, ozone, water vapor, ammonia, and dialkyl sulfide, more preferably contains at least one selected from the group consisting of hydrogen, oxygen, ozone, water vapor, and ammonia, and even more preferably contains at least one selected from the group consisting of ozone and water vapor.

[0146] In this step, the water vapor used as the reactive gas 107 may be a gas consisting of water vapor alone, or may be a mixed gas containing water vapor and other gases such as argon, nitrogen, oxygen, and hydrogen. When the reactive gas 107 is the mixed gas, the concentration of water vapor in the mixed gas is preferably in the range of 0.001% by volume to 99% by volume, more preferably in the range of 0.001% by volume to 50% by volume, and even more preferably in the range of 0.001% by volume to 10% by volume, from the viewpoint of improving the reaction between the precursor thin film and the reactive gas 107.

[0147] In this step, a thermal reaction, plasma, photoreaction, or the like may be used to promote the formation of the thin film.

[0148] Examples of methods that utilize a thermal reaction include a method of heating the substrate, or a method of heating the inside of the film formation chamber 100 in which the substrate is placed. The heater for heating may be installed outside the film formation chamber 100, or may be installed inside the film formation chamber 100 to heat only the substrate and its surroundings. The heating temperature in this step may be in the range of room temperature or higher and 500°C or lower, preferably in the range of 100°C or higher and 450°C or lower, more preferably in the range of 130°C or higher and 400°C or lower, and even more preferably in the range of 150°C or higher and 300°C or lower.

[0149] Furthermore, from the viewpoint of achieving a good reaction between the precursor thin film and the reactive gas 107, the pressure (system pressure) within the film formation chamber 100 in this step is preferably in the range of 1 Pa or more and 10,000 Pa or less, and more preferably in the range of 10 Pa or more and 1,000 Pa or less.

[0150] An example of a method using plasma is to generate plasma in the film formation chamber 100 and excite the precursor thin film, the substrate, or the reactive gas 107. An example of a mechanism for generating plasma is to generate plasma by applying a high-frequency voltage to the film formation chamber 100 using a radio-frequency (RF) power supply 113 installed outside the film formation chamber 100. In this step, if the power when applying the voltage is too high, the damage to the substrate will be significant, so the power is preferably in the range of 10 W or more and 1,500 W or less, more preferably in the range of 30 W or more and 1,000 W or less, and even more preferably in the range of 50 W or more and 600 W or less.

[0151] Examples of methods that utilize photoreaction include methods that use ultraviolet lamps (particularly low-pressure mercury lamps, etc.), which can suppress film damage caused by charged particles compared to methods that utilize plasma.

[0152] C3. Other Steps The method for producing a thin film according to the present disclosure may include other steps such as an exhaust step, an annealing step, and a reflow step.

[0153] (1) Exhaust Step The thin film manufacturing method of the present disclosure may include an exhaust step, after the above "C1. Precursor Thin Film Formation Step" or after the above "C2. Thin Film Formation Step," in which source gases not involved in the formation of the precursor thin film or thin film, reactive gas 107, and by-product gases generated during the formation of the precursor thin film or thin film are exhausted 109 from the film formation chamber 100. In the exhaust step, it is ideal that the source gases, reactive gas 107, and by-product gases are completely exhausted from the film formation chamber 100, but complete exhaust is not necessarily required. Examples of exhaust methods include a method of purging by introducing a purge gas 108 such as helium, nitrogen, or argon into the film formation chamber 100, a method of exhausting by reducing the pressure inside the film formation chamber 100, and a combination of these methods. The degree of pressure reduction when reducing the pressure inside the film formation chamber 100 is preferably within the range of 0.01 Pa or more and 300 Pa or less, more preferably within the range of 0.05 Pa or more and 200 Pa or less, and even more preferably within the range of 0.1 Pa or more and 100 Pa or less, from the viewpoint that the source gas, reactive gas 107, and by-product gas are sufficiently exhausted 109, and a high-quality rare-earth element-containing thin film with little residual carbon is easily formed.

[0154] (2) Annealing Step The thin film manufacturing method of the present disclosure can include a step of annealing the rare earth-containing thin film after its formation to improve the electrical properties of the rare earth-containing thin film. In the annealing step, the rare earth-containing thin film can be annealed in an inert atmosphere, an oxidizing atmosphere, or a reducing atmosphere. From the viewpoint of facilitating the formation of a high-quality rare earth-containing thin film with little residual carbon, the temperature in the annealing step is preferably in the range of 200°C to 600°C, more preferably in the range of 230°C to 550°C, and even more preferably in the range of 250°C to 500°C.

[0155] (3) Reflow Step The thin film manufacturing method of the present disclosure can include a reflow step to fill in any unevenness in the rare earth element-containing thin film. From the viewpoint of facilitating the formation of a high-quality rare earth element-containing thin film with little residual carbon, the reflow step is preferably carried out at a temperature in the range of 200°C to 600°C, more preferably 230°C to 550°C, and even more preferably 250°C to 500°C.

[0156] C4. Film Formation Cycle In the thin film manufacturing method of the present disclosure, a precursor thin film formation step, an evacuation step, a thin film formation step, and an evacuation step are performed in sequence to form a rare earth element-containing thin film through a series of operations, which constitutes one cycle. By repeating this cycle, a rare earth element-containing thin film having a desired thickness can be manufactured. In other words, the thickness of the manufactured rare earth element-containing thin film can be controlled by the number of cycles. For example, the above cycle may be performed only once to manufacture a single layer of rare earth element-containing thin film, or may be performed two or more times to manufacture a rare earth element-containing thin film having a desired thickness.

[0157] C5. Thin Film Manufacturing Methods Other Than ALD Methods In this embodiment, a method for manufacturing a rare earth element-containing thin film by ALD has been described. However, the thin film manufacturing method of the present disclosure is not limited to the above. For example, it may include a CVD method in which a compound represented by the general formula (1) in a source gas obtained by vaporizing a thin film-forming raw material is decomposed, or a compound represented by the general formula (1) in the source gas is reacted with a reactive gas to form a rare earth element-containing thin film. Furthermore, in addition to the above-mentioned ALD and CVD methods, thin films may also be manufactured by MOD methods such as sputtering, ion plating, coating pyrolysis, and sol-gel methods. Among these, ALD methods are preferred for manufacturing thin films because they have many advantages, such as excellent composition controllability and step coverage, suitability for mass production, and the ability to achieve hybrid integration.

[0158] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the following examples.

[0159] [Production Example 1] Yttrium Compound (M=Y, R 1 =iPr,R 2 =sPe,R 3 =H, n=3) In an argon atmosphere, a 100 mL three-neck flask was charged with Y[N(SiMe ３ ) ２ ] ３ (2.06 g, 0.00361 mol) and toluene (5.73 mL) were charged and cooled on ice. N-sec-pentyl-N'-isopropylformamidine (1.69 g, 0.0108 mol) was added dropwise thereto. After warming to room temperature, the mixture was stirred for 18 hours, and then the solvent was removed. The residue was distilled using a Kugelrohr distillation apparatus at a temperature of 160°C and a pressure of 17 Pa, obtaining 1.13 g of the target product in a yield of 56%.

[0160] (Analytical Values) (1) Atmospheric Pressure TG-DTA Temperature at 50% Mass Loss (°C): 262°C (Ar flow rate: 100 ml / min, temperature increase rate: 10°C / min, sample amount: 9.809 mg) (2) 1H-NMR (solvent: deuterated benzene) (chemical shift: multiplicity: hydrogen number) (0.969-0.986: triplet: 9) (1.193-1.259: multiplet: 27) (1.286-1.334: multiplet: 3) (1.396- 1.546: multiplet: 9) (2.860-2.890: multiplet: 3) (3.077-3.173: septet: 3) (8.256: singlet: 3) (3) ICP analysis chlorine content: 2.36ppm

[0161] [Production Example 2] Yttrium Compound (M=Y, R 1 =iPr,R 2 =sBu,R 3 =H, n=3) In an argon atmosphere, a 100 mL three-neck flask was charged with Y[N(SiMe ３ ) ２ ] ３(2.22 g, 0.00390 mol) and toluene (9.81 mL) were charged and cooled on ice. N-sec-butyl-N'-isopropylformamidine (1.70 g, 0.0117 mol) was added dropwise thereto. After warming to room temperature, the mixture was stirred for 18 hours, and then the solvent was removed. The residue was distilled using a Kugelrohr distillation apparatus at a temperature of 160°C and a pressure of 25 Pa, obtaining 0.54 g of the target product in a yield of 25%.

[0162] (Analytical Values) (1) Atmospheric Pressure TG-DTA Temperature (°C) at 50% mass loss: 245°C (Ar flow rate: 100 ml / min, temperature increase rate: 10°C / min, sample amount: 10.186 mg) (2) 1H-NMR (solvent: deuterated benzene) (chemical shift: multiplicity: hydrogen number) (0.890-0.995: triplet: 9) (1.188-1.256: multiplet: 27) (1.469-1.543: multiplet: 6) (2.741-2.789: multiplet: 3) (3.102-3.137: septet: 3) (8.248: singlet: 3)

[0163] [Production Example 3] Ytterbium compound (M=Yb, R 1 =iPr,R 2 =sPe,R 3 =H, n=3) In an argon atmosphere, a 100 mL three-neck flask was charged with Yb[N(SiMe ３ ) ２ ] ３ (2.05 g, 0.00313 mol) and toluene (7.87 mL) were charged and cooled on ice. N-sec-pentyl-N'-isopropylformamidine (1.50 g, 0.00939 mol) was added dropwise thereto. After warming to room temperature, the mixture was stirred for 18 hours, and then the solvent was removed. The residue was distilled using a Kugelrohr distillation apparatus at a temperature of 170°C and a pressure of 25 Pa, and 0.86 g of the target product was obtained in a yield of 43%.

[0164] (Analysis Values) (1) Atmospheric Pressure TG-DTA Temperature at 50% Mass Loss (°C): 262°C (Ar flow rate: 100 ml / min, temperature increase rate: 10°C / min, sample amount: 11.018 mg)

[0165] [Production Example 4] Lutetium compound (M = Lu, R 1 =iPr,R 2 =sPe,R 3 =H, n=3) was placed in a 100 mL three-neck flask under an argon atmosphere. ３ ) ２ ] ３ (1.50 g, 0.00229 mol) and toluene (3.63 mL) were charged and cooled on ice. N-sec-pentyl-N'-isopropylformamidine (1.07 g, 0.00686 mol) was added dropwise thereto. After warming to room temperature, the mixture was stirred for 22 hours, and then the solvent was removed. The residue was distilled using a Kugelrohr distillation apparatus at a temperature of 172°C and a pressure of 46 Pa, yielding 0.73 g of the target product in a 50% yield.

[0166] (Analytical Values) (1) Atmospheric Pressure TG-DTA Temperature (°C) at 50% mass loss: 261°C (Ar flow rate: 100 ml / min, temperature increase rate: 10°C / min, sample amount: 9.983 mg) (2) 1H-NMR (solvent: deuterated benzene) (chemical shift: multiplicity: hydrogen number) (0.952-0.987: triplet: 9) (1.195-1.256: multiplet: 27) (1.276-1.358: multiplet: 3) (1.363- 1.590: multiplet: 9) (2.953-3.032: multiplet: 3) (3.187-3.282: septet: 3) (8.308: singlet: 3)

[0167] [Comparative Example 1] Comparative compound 1 (M=Y,R 1 =iPr,R 2 =iPr,R 3 =H, n=3) In an argon atmosphere, a 500 mL four-neck flask was charged with Y[N(SiMe ３ ) ２ ] ３ (31.0 g, 0.0543 mol) and toluene (86 mL) were charged and cooled on ice. A solution of N,N'-diisopropylformamidine (20.9 g, 0.163 mol) dissolved in toluene (86 mL) was added dropwise to the mixture. After warming to room temperature, the mixture was stirred for 18 hours, and then the solvent was removed. The residue was sublimated at a temperature of 134°C and a pressure of 24 Pa, and 22.3 g of the target product was obtained in an 87% yield.

[0168] (Analytical Values) (1) Normal Pressure TG-DTA Temperature (°C) at 50% mass loss: 231°C (Ar flow rate: 100 ml / min, temperature increase rate: 10°C / min, sample amount: 9.948 mg) (2) 1H-NMR (solvent: deuterated benzene) (chemical shift: multiplicity: hydrogen number) (1.190-1.206: doublet: 36) (3.044-3.142: multiplet: 6) (8.235-8.243: doublet: 3) (3) ICP analysis: chlorine content: 802 ppm

[0169] The compounds represented by the general formula (1) prepared in Preparation Examples 1 to 4 and the comparative compounds 1 to 3 were used to carry out the following evaluations.

[0170]

[0171] (1) Temperature (°C) at 50% mass reduction in atmospheric pressure TG-DTA Measurements were performed using a TG-DTA at 760 Torr, an argon flow rate of 100 mL / min, a heating rate of 10°C / min, and a scanning temperature range of 30°C to 600°C. The temperature (°C) at which the weight of the test compound was reduced by 50% by mass was evaluated as the "temperature (°C) at 50% mass reduction in atmospheric pressure TG-DTA." A lower temperature (°C) at 50% mass reduction in atmospheric pressure TG-DTA indicates that vapor can be obtained at a lower temperature. The results are shown in Table 3.

[0172] (2) Melting Point Evaluation The state of the compound at normal pressure and 25°C was visually observed. For compounds that were solid at 25°C, measurements were performed using a differential scanning calorimeter (DSC) at a heating rate of 10°C / min over a scanning temperature range of 30°C to 600°C. In the resulting chart, the melting point (°C) was evaluated as the temperature at the intersection of a straight line extending the low-temperature baseline toward the high-temperature side and a tangent drawn at the point where the gradient of the curve on the low-temperature side of the peak indicating an endothermic reaction is maximum. The results are shown in Table 3.

[0173] (3) Thermal decomposition onset temperature (°C) Using a differential scanning calorimeter (DSC), measurements were taken at a heating rate of 10°C / min over a scanning temperature range of 30°C to 600°C. In the DSC chart, the onset of the exothermic or endothermic peak of the compound was evaluated as the thermal decomposition onset temperature (°C). A higher temperature indicates better thermal stability. The results are shown in Table 3.

[0174]

[0175] All of Examples 1 to 4 showed melting points much lower than the corresponding Comparative Examples. Furthermore, Examples 1 to 3 showed higher thermal decomposition onset temperatures than the corresponding Comparative Examples, demonstrating excellent thermal stability. Although Example 4 showed a lower thermal decomposition onset temperature than Comparative Example 3, it exhibited sufficiently high thermal stability and presented no practical problems. Furthermore, in the Examples, the temperature at 50% mass loss in atmospheric pressure TG-DTA was higher than in the Comparative Examples, but the Examples exhibited excellent volatility as thin film-forming raw materials and did not impede thin film formation.

[0176] [Example 5] Production of a thin film by the ALD method using an yttrium compound The yttrium compound (M=Y, R 1 =iPr,R 2 =sPe,R 3 =H, n=3) was used as a thin film forming source, and a thin film containing yttrium oxide was produced on a silicon substrate as a base by the ALD method under the following conditions using the ALD apparatus shown in Figure 1.

[0177] (Conditions) Manufacturing method: ALD method Reaction temperature (substrate temperature): 200°C Reactive gas: water vapor

[0178] (Steps) A series of steps (1) to (4) below constitute one cycle, and 100 cycles were repeated. (1) The vapor of a thin-film-forming raw material (raw material gas: a compound represented by general formula (1)) obtained by vaporization under conditions of a raw material container temperature of 150°C and a raw material container internal pressure of 100 Pa was introduced into a film-forming chamber, and the compound represented by general formula (1) in the raw material gas was deposited on the surface of the substrate at a system pressure of 100 Pa for 10 seconds to form a precursor thin film (precursor thin-film forming step). (2) Undeposited raw material gas was purged with argon for 30 seconds (exhaust step). (3) A reactive gas was introduced into the film-forming chamber, and the precursor thin film and the reactive gas were reacted with each other at a system pressure of 100 Pa for 0.1 seconds (thin-film forming step). (4) Unreacted reactive gas and by-product gas were purged with argon for 120 seconds (exhaust step).

[0179] Comparative Example 4: Production of a thin film by ALD using a yttrium compound, Comparative Compound 1. A thin film containing yttrium oxide was produced on a silicon substrate by the same procedure as in Example 5, except that the thin film-forming raw material was changed to Comparative Compound 1 and the temperature of the raw material container was changed from 150°C to 110°C in (1) the precursor thin film formation step.

[0180] (Evaluation) For the thin films obtained in Example 5 and Comparative Example 4, the thickness of the thin film was measured by X-ray reflectivity, the surface of the thin film was observed using SEM images, the composition of the thin film was analyzed by X-ray diffraction, and the carbon content in the thin film was measured by X-ray photoelectron spectroscopy. These results are shown in Table 4 below.

[0181] *1: The detection limit is 0.1 atm%.

[0182] The thin film manufacturing method of Comparative Example 4 used a high-melting-point precursor, which made it prone to clogging of valves and piping over long-term use and resulted in an unstable supply of vapor. In contrast, Example 5 confirmed that the thin film manufacturing method of the present disclosure uses a compound represented by general formula (1), which has a low melting point and excellent thermal stability and volatility, as a thin film-forming raw material, which prevents clogging of valves and piping, stabilizes the supply of vapor, reduces residual carbon in the thin film, and enables the production of high-quality rare earth element-containing thin films with excellent surface uniformity, with good productivity.

[0183] 100 Film formation chamber 101 Source container 102 Vaporization chamber 103 Heater 104 Mass flow controller (MFC) 105 Vacuum pump 106 Cold trap 107 Reactive gas 108 Purge gas 109 Exhaust 110 Carrier gas 111 Carrier gas 112 Automatic pressure controller 113 Radio frequency (RF) power supply 114 RF matching system

Claims

1. A thin film forming material containing a compound represented by the following general formula (1): M(L) ｎ (1) (In general formula (1), M represents a rare earth element other than lanthanum, L represents an amidinate ligand represented by the following general formula (2), and n represents an integer of 2 to 4.) (In general formula (2), R １ and R ２ each independently represents an alkyl group having 1 to 8 carbon atoms; R ３ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and * represents the bonding position with M. １ and R ２ are different groups.) 2. R in the general formula (2) １ and R ２ 2. The thin film-forming material according to claim 1, comprising a compound in which the total number of carbon atoms in the group represented by the formula (I) is 7 or more and 15 or less, and n is 3.

3. The thin film forming material according to claim 1 or 2, wherein the thin film forming material is a material used in thin film formation by atomic layer deposition.

4. A thin film produced using the thin film forming material according to claim 1 or 2.

5. A method for producing a thin film, comprising forming a thin film containing a rare earth element using the thin film forming material according to claim 1 or 2.

6. A method for producing a thin film according to claim 5, comprising decomposing the compound represented by general formula (1) in a source gas obtained by vaporizing the thin film-forming raw material, or reacting the compound represented by general formula (1) with a reactive gas to form a thin film containing a rare earth element.

7. The method for producing a thin film according to claim 6, comprising: a precursor thin film formation step of introducing a source gas obtained by vaporizing the thin film-forming source into a film formation chamber in which a substrate is placed, and forming a precursor thin film on the surface of the substrate; and a thin film formation step of introducing a reactive gas into the film formation chamber, and reacting the precursor thin film with the reactive gas, to form a thin film containing a rare earth element.

8. A rare earth element compound represented by the following general formula (3): (In the general formula (3), M represents a rare earth element other than lanthanum, and R ４ and R ５ each independently represents an alkyl group having 1 to 8 carbon atoms; R ６ represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. ４ and R ５ are different groups, and R ４ and R ５ The total number of carbon atoms in the group represented by the formula (I) is 7 or more and 15 or less.

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