JP7796014B2 - Thin film forming material, thin film, and method for manufacturing thin film - Google Patents

Description

The present invention relates to a raw material for forming a thin film containing an yttrium compound having a specific structure, a thin film obtained using the raw material, and a method for producing the thin film.

In the semiconductor manufacturing industry, metal-containing complexes are being investigated as raw materials for forming thin films such as metal nitrides, metal oxides, and metal-containing films on substrates such as silicon.

Yttrium is used as a component in compound semiconductors, and various compounds have been reported as raw materials for forming thin films containing yttrium.

Methods for producing thin films include, for example, sputtering, ion plating, metal organic decomposition (MOD) methods such as thermal coating and sol-gel methods, chemical vapor deposition (CVD), and atomic layer deposition (ALD). Of these, CVD and ALD are primarily used due to the high quality of the thin films they produce.

Various thin film formation materials that can be used in vapor phase thin film formation methods such as CVD and ALD have been reported, but thin film formation materials that can be used in ALD must have a sufficiently wide temperature range known as the ALD window. It is common knowledge in the technical field that thin film formation materials that can be used in CVD are often not suitable for ALD.

For example, Patent Document 1 proposes a metal-containing complex with a β-ketoiminate structure having -R ⁴ -NR ⁵ R ⁶ (R ⁴ is an alkylene bridging group, and R ⁵ and R ⁶ are selected from alkyl groups and the like) in the N side chain as a thin film-forming raw material for forming a thin film containing yttrium.

Patent document 2 proposes a metal-containing complex containing a multidentate ketoimine ligand and an alkoxy or amino ligand as a precursor for forming a metal film or a metal oxide film.

Patent Document 3 discloses the use of an yttrium compound having a β-ketoimine ligand as a catalyst for conjugated diene polymerization.

Japanese Patent No. 4680953 (JP 2007-302656 A) Japanese Patent No. 5698161 (JP 2012-153688 A) Patent No. 6020257 (JP 2014-166967 A)

Thin film-forming raw materials are required to have a low melting point, high volatility, high thermal stability, and the ability to form high-quality thin films with little residual carbon. However, the thin film-forming raw materials containing yttrium compounds proposed in Patent Documents 1 and 2 do not satisfy these requirements.

Patent Document 3 did not contain any disclosure suggesting the use of yttrium compounds having β-ketoimine ligands as raw materials for forming thin films.

Therefore, the present invention aims to provide a thin film-forming raw material containing an yttrium compound that has a low melting point, high volatility, and high thermal stability, and can be suitably used in CVD and ALD processes. The present invention also aims to provide a thin film obtained using the thin film-forming raw material, and a method for producing the thin film.

As a result of extensive research, the present inventors have found that a thin film-forming raw material containing an yttrium compound having a specific structure can solve the above problems, and have thus completed the present invention.
That is, the present invention is a thin film-forming material containing an yttrium compound represented by the following general formula (1) or (2).

(In the formula, ^R1 and ^R3 each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxyalkyl group having 2 to 6 carbon atoms; ^R2 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; ^R4 represents an alkanediyl group having 1 to 5 carbon atoms; and ^R5 represents an alkyl group having 1 to 3 carbon atoms; and multiple ^R1s , ^R2s , ^R3s , ^R4s , and ^R5s may be the same or different.)

(In the formula, ^R6 and ^R8 each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxyalkyl group having 2 to 6 carbon atoms; ^R7 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms; and multiple ^R6s , ^R7s , and ^R8s may be the same or different, provided that at least one of ^R6s and ^R8s represents an alkoxyalkyl group having 2 to 6 carbon atoms.)

The thin film-forming raw material of the present invention preferably contains an yttrium compound in which ^R1 and ^R3 are isopropyl groups, ^R2 is a hydrogen atom, ^R4 is an ethylene group, and ^R5 is a methyl group in the above general formula (1), or an yttrium compound in which ^R6 is a methoxy tert-butyl group, ^R7 is a hydrogen atom, and ^R8 is an isopropyl group in the above general formula (2), because these have a low melting point and high volatility and thermal stability.

The present invention also relates to a method for producing a thin film, which includes the steps of: introducing a source gas obtained by vaporizing the above-mentioned thin film-forming source material into a film-forming chamber in which a substrate is placed; depositing an yttrium compound in the source gas on the surface of the substrate to form a precursor thin film; and introducing a reactive gas into the film-forming chamber and reacting the precursor thin film with the reactive gas to form a thin film containing yttrium atoms on the surface of the substrate.

Furthermore, in the thin film manufacturing method of the present invention, it is preferable that the reactive gas is an oxidizing gas and the thin film containing yttrium atoms is yttrium oxide.

Furthermore, in the thin film manufacturing method of the present invention, it is more preferable that the above-mentioned oxidizing gas is a gas containing oxygen, ozone or water vapor.

In addition, in the thin film manufacturing method of the present invention, it is preferable to react the precursor thin film with the reactive gas at a temperature range of 100°C to 400°C.

According to the present invention, by containing a specific yttrium compound, it is possible to provide a thin film-forming raw material that has a low melting point and is highly volatile and thermally stable. Furthermore, by using the thin film-forming raw material of the present invention, it is possible to produce high-quality yttrium-containing thin films with low residual carbon content using the CVD method, particularly the ALD method.

1 is a schematic diagram showing an example of an ALD apparatus used in a thin film manufacturing method according to the present invention. FIG. 1 is a schematic diagram showing another example of an ALD apparatus used in the thin film manufacturing method according to the present invention. FIG. 10 is a schematic diagram showing yet another example of an ALD apparatus used in the thin film manufacturing method according to the present invention. FIG. 10 is a schematic diagram showing yet another example of an ALD apparatus used in the thin film manufacturing method according to the present invention.

<Raw material for thin film formation>
The thin film-forming material of the present invention contains the yttrium compound represented by the above general formula (1) or (2).

In the above general formula (1), ^R1 and ^R3 each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxyalkyl group having 2 to 6 carbon atoms, ^R2 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, ^R4 represents an alkanediyl group having 1 to 5 carbon atoms, and ^R5 represents an alkyl group having 1 to 3 carbon atoms, and multiple ^R1s , ^R2s , ^R3s , ^R4s , and ^R5s may be the same or different.

In the above general formula (2), ^R6 and ^R8 each independently represent an alkyl group having 1 to 6 carbon atoms or an alkoxyalkyl group having 2 to 6 carbon atoms, ^R7 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, and multiple ^R6s , ^R7s , and ^R8s may be the same or different, provided that at least one of ^R6s and ^R8s represents an alkoxyalkyl group having 2 to 6 carbon atoms.

The yttrium compound represented by the above general formula (1) or (2) is used as a precursor for forming a thin film by the CVD or ALD method, so it preferably has a melting point of 100°C or less, and is more preferably a liquid at room temperature. Furthermore, the temperature at which the yttrium compound loses 50% by mass as measured by reduced pressure thermogravimetry-differential thermal analysis (TG-DTA) is preferably 240°C or less.

The thermal decomposition onset temperature of the yttrium compound measured by differential scanning calorimetry (DSC) is preferably 250°C or higher, and more preferably 300°C or higher.

In the above general formula (1), examples of the alkyl group having 1 to 6 carbon atoms represented by R ¹ and R ³ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an isobutyl group, an n-pentyl group, a sec-pentyl group, a tert-pentyl group, an isopentyl group, a neopentyl group, and a hexyl group. From the viewpoint of achieving a remarkable effect of the present invention, a yttrium compound in which R ¹ and R ³ are alkyl groups having 1 to 4 carbon atoms in the above general formula (1) is preferred, a yttrium compound in which R ¹ is an ethyl group, an isopropyl group, or a tert-butyl group, and R ³ is an ethyl group or an isopropyl group is more preferred, and a yttrium compound in which R ¹ and R ³ are isopropyl groups is most preferred.

In the above general formula (1), examples of the alkoxyalkyl group having 2 to 6 carbon atoms represented by R ¹ and R ³ include a methoxymethyl group, a methoxyethyl group, an ethoxymethyl group, an ethoxyethyl group, a methoxyisopropyl group, a methoxypropyl group, a methoxyisobutyl group, a methoxy sec-butyl group, a methoxy tert-butyl group, an ethoxyisopropyl group, an ethoxybutyl group, an ethoxyisobutyl group, an ethoxy sec-butyl group, an ethoxy tert-butyl group, etc. From the viewpoint of achieving a significant effect of the present invention, a yttrium compound in which R ¹ and R ³ are a methoxyisopropyl group or a methoxy tert-butyl group in the above general formula (1) is preferred.

In the above general formula (1), examples of the alkyl group having 1 to 3 carbon atoms represented by ^R2 and ^R5 include the above-mentioned alkyl groups having 1 to 3 carbon atoms. From the viewpoint of achieving a significant effect of the present invention, a yttrium compound in which ^R2 is a hydrogen atom and ^R5 is a methyl group in the above general formula (1) is preferred.

In the above general formula (1), examples of the alkanediyl group having 1 to 5 carbon atoms represented by R ⁴ include a methylene group, an ethylene group, a propane-1,3-diyl group, a propane-1,2-diyl group, a butylene group, a butane-1,2-diyl group, a butane-1,3-diyl group, a butane-1,4-diyl group, etc. From the viewpoint of achieving a significant effect of the present invention, a yttrium compound in which R ⁴ in the above general formula (1) is an ethylene group or a propane-1,2-diyl group is preferred.

In the above general formula (2), examples of the alkyl group having 1 to 6 carbon atoms and the alkoxyalkyl group having 2 to 6 carbon atoms represented by R ⁶ and R ⁸ are the same as those mentioned above.

In the above general formula (2), examples of the alkyl group having 1 to 3 carbon atoms represented by R ⁷ include the same as those mentioned above.

In the above general formula (2), the plurality of R ^{6 s} , R ^{7 s} , and R ⁸ s may be the same or different, but at least one of the plurality of R ^{6 s} and R ^{8 s} is an alkoxyalkyl group having 2 to 6 carbon atoms. In the above general formula (2), a yttrium compound in which two or more of the plurality of R ^{6 s} and R ^{8 s} are alkoxyalkyl groups having 2 to 6 carbon atoms is preferred, and a yttrium compound in which three of the plurality of R ^{6 s} and R ^{8 s} are alkoxyalkyl groups having 2 to 6 carbon atoms is more preferred.

Preferred specific examples of yttrium compounds represented by general formula (1) or (2) above include the yttrium compounds No. 1 to No. 16 below, but the present invention is not limited to these yttrium compounds. In the yttrium compounds No. 1 to No. 16 below, "Me" represents a methyl group, "Et" represents an ethyl group, "iPr" represents an isopropyl group, and "tBu" represents a tert-butyl group.

Among the above yttrium compounds, yttrium compounds No. 1, No. 3, No. 6, and No. 15 are preferred because they exhibit particularly significant effects of the present invention.

The yttrium compound of the present invention can be produced by utilizing well-known reactions. For example, in the above general formula (1), an yttrium compound in which R ¹ is a methyl group, R ² is a hydrogen atom, R ³ is a methyl group, R ⁴ is a methylene group, and R ⁵ is a methyl group can be obtained by reacting yttrium-tris-trimethylsilylamide with 4-methoxymethylamino-3-penten-2-one in a solvent, followed by removing the solvent and purifying by distillation. In addition, in the above general formula (2), an yttrium compound in which R ⁶ is a methoxy tert-butyl group, R ⁷ is a hydrogen atom, and R ⁸ is an isopropyl group can be obtained by reacting yttrium-tris-trimethylsilylamide with 5-amino-7-methoxy-4-hepten-3-one in a solvent, followed by removing the solvent and purifying by distillation.

The thin-film-forming raw material of the present invention may contain a yttrium compound represented by the above general formula (1) or (2), and its composition will vary depending on the type of thin film desired. For example, when producing a thin film containing only yttrium as the metal, the thin-film-forming raw material of the present invention does not contain compounds containing metals other than yttrium or compounds containing metalloids. On the other hand, when producing a thin film containing yttrium and metals and/or metalloids other than yttrium, the thin-film-forming raw material of the present invention may contain, in addition to the yttrium compound represented by the above general formula (1) or (2), compounds containing the desired metals and/or compounds containing metalloids (hereinafter sometimes referred to as "other precursors").

In addition, in the case of a multi-component CVD method using multiple precursors, other precursors that can be used together with the yttrium compound represented by the above general formula (1) or (2) are not particularly limited, and well-known general precursors used as raw materials for forming thin films for the CVD method can be used.

Examples of the other precursors mentioned above include compounds of silicon or 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, magnesium, aluminum, potassium, calcium, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, rubidium, strontium, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, indium, tin, antimony, barium, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, gold, lead, bismuth, radium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

Examples of alcohol compounds that can be used as organic ligands for the other precursors mentioned above 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.

Examples of glycol compounds used as organic ligands for the other precursors mentioned above 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.

Examples of β-diketone compounds that can be used as organic ligands for the other precursors mentioned above 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- 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.

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

Organic amine compounds used as organic ligands for the other precursors mentioned above include methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, tert-butylamine, isobutylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, ethylmethylamine, propylmethylamine, isopropylmethylamine, etc.

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

The above-mentioned multi-component CVD method includes a method in which each component of the thin film-forming raw material is vaporized and supplied independently (hereinafter sometimes referred to as the "single-source method"), and a method in which a mixed raw material in which multi-component raw materials are pre-mixed to the desired composition is vaporized and supplied (hereinafter sometimes referred to as the "cocktail-source method"). In the single-source method, the other precursor is preferably a compound whose thermal and/or oxidative decomposition behavior is similar to that of the yttrium compound represented by general formula (1) or (2) above. In the cocktail-source method, the other precursor is preferably a compound whose thermal and/or oxidative decomposition behavior is similar to that of the yttrium compound represented by general formula (1) or (2) above, and which does not undergo deterioration due to chemical reactions or the like when mixed.

In the case of the cocktail source method in a multi-component CVD method, a mixture of the yttrium compound represented by the above general formula (1) or (2) with other precursors, or a mixed solution obtained by dissolving such a mixture in an organic solvent, can be used as a raw material for forming a thin film.

There are no particular restrictions on the organic solvent, and any well-known organic solvent can be used. Examples of the organic solvent include acetates such as ethyl acetate, butyl acetate, and methoxyethyl acetate; ethers such as tetrahydrofuran, tetrahydropyran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, dibutyl ether, and dioxane; ketones such as methyl butyl ketone, methyl isobutyl ketone, ethyl butyl ketone, dipropyl ketone, diisobutyl ketone, methyl amyl ketone, cyclohexanone, and methylcyclohexanone; hydrocarbons such as hexane, cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, heptane, octane, toluene, and xylene; hydrocarbons having a cyano group such as 1-cyanopropane, 1-cyanonobutane, 1-cyanohexane, cyanocyclohexane, cyanobenzene, 1,3-dicyanopropane, 1,4-dicyanobutane, 1,6-dicyanohexane, 1,4-dicyanocyclohexane, and 1,4-dicyanobenzene; pyridine, lutidine, and the like. These organic solvents may be used alone or in combination of two or more depending on the solubility of the solute, the relationship between the temperature used and the boiling point, the flash point, and the like.

When the thin film-forming raw material of the present invention is a mixed solution containing the above-mentioned organic solvent, the total amount of precursors in the thin film-forming raw material is preferably adjusted to be 0.01 mol/L to 2.0 mol/L, more preferably 0.05 mol/L to 1.0 mol/L.

Here, the total amount of precursors refers to the amount of yttrium compounds represented by general formula (1) or (2) above when the thin-film-forming raw material of the present invention does not contain compounds containing metals other than yttrium or compounds containing metalloids. (However, when the thin-film-forming raw material of the present invention further contains other precursors containing yttrium, the total amount of precursors refers to the combined amount of yttrium compounds represented by general formula (1) or (2) above and other precursors containing yttrium.) When the thin-film-forming raw material of the present invention contains other precursors in addition to the yttrium compound represented by general formula (1) or (2), the total amount of precursors refers to the combined amount of yttrium compounds represented by general formula (1) or (2) above and other precursors.

Furthermore, the thin-film-forming raw material of the present invention may contain a nucleophilic reagent, if necessary, to improve the stability of the yttrium compound represented by the above general formula (1) or (2) and other precursors. Examples of such nucleophilic reagents 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; Examples of suitable nucleophilic reagents 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. The amount of these nucleophilic reagents used is preferably in the range of 0.1 mol to 10 mol, and more preferably in the range of 1 mol to 4 mol, per mol of the total amount of precursor.

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

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 of the present invention contains as few particles as possible. Specifically, when particles are measured 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 even more preferable that the number of particles larger than 0.2 μm per 1 ml of liquid phase is 100 or less.

<Method of manufacturing thin film>
Next, the method for producing a thin film of the present invention using the above-mentioned thin film-forming raw materials will be described.
Here, as one embodiment, a method for producing a thin film containing yttrium atoms (hereinafter, also referred to as an "yttrium-containing thin film") by the ALD method will be described.

The apparatus used in the thin film manufacturing method of the present invention can be a well-known ALD apparatus. Specific examples of such apparatus include an apparatus capable of supplying a precursor by bubbling, as shown in Figures 1 and 3, and an apparatus having a vaporization chamber, as shown in Figures 2 and 4. Other examples include an apparatus capable of performing plasma treatment on a reactive gas, as shown in Figures 3 and 4. It should be noted that this is not limited to single-wafer apparatuses like those shown in Figures 1 to 4; it is also possible to use an apparatus capable of simultaneously processing multiple wafers using a batch furnace. These apparatuses can also be used as CVD apparatus.

The thin film manufacturing method of the present invention includes the steps of introducing a source gas obtained by vaporizing the above-described thin film-forming source material into a film formation chamber (hereinafter sometimes referred to as a "deposition reaction section") in which a substrate is placed (source gas introduction step), depositing an yttrium compound in the source gas on the surface of the substrate to form a precursor thin film (precursor thin film formation step), and introducing a reactive gas into the film formation chamber and reacting the precursor thin film with the reactive gas to form an yttrium-containing thin film on the surface of the substrate (yttrium-containing thin film formation step). Furthermore, the thin film manufacturing method of the present invention preferably includes a step of evacuating gas from the film formation chamber between the precursor thin film formation step and the yttrium-containing thin film formation step and/or after the yttrium-containing thin film formation step (evacuation step).

In one embodiment of the thin film manufacturing method of the present invention, deposition through a series of operations, including a precursor thin film formation process, an evacuation process, an yttrium-containing thin film formation process, and an evacuation process, is performed in this order, forming one cycle. By repeating this cycle, the thickness of the thin film of the present invention can be adjusted. Each step of the thin film manufacturing method of the present invention is described below.

(Source gas introduction step)
The source gas introduction step is a step of vaporizing the thin film forming source material to form a source gas, and introducing the source gas into a deposition reaction section in which a substrate is placed.
Methods for transporting and supplying thin-film precursors include a gas transport method, as shown in FIGS. 1 and 3 , in which the precursor is heated and/or depressurized in a container (hereinafter sometimes referred to as a “source container”) in which the precursor is stored to form a source gas, and then introduced into a deposition reactor containing a substrate, optionally together with a carrier gas such as argon, nitrogen, or helium. Another method, as shown in FIGS. 2 and 4 , involves transporting the precursor in a liquid or solution state to a vaporization chamber, where it is heated and/or depressurized to form a source gas, and then introducing the source gas into a deposition reactor containing a substrate. In the gas transport method, the yttrium compound represented by the general formula (1) or (2) itself can be used as the thin-film precursor. In the liquid transport method, the yttrium compound represented by the general formula (1) or (2) or a solution of the yttrium compound dissolved in an organic solvent can be used as the thin-film precursor. These thin-film precursors may further contain a nucleophilic reagent or the like.

In addition to the gas transport and liquid transport methods described above, methods that can be used in the source gas introduction process include the single source method and cocktail source method described in <Thin Film Forming Raw Materials>, which are multi-component ALD methods containing multiple precursors. Regardless of which introduction method is used, the thin film forming raw material of the present invention is preferably vaporized within a temperature range of 0°C to 200°C. Furthermore, when the thin film forming raw material is vaporized in a source container or vaporization chamber to produce a source gas, the pressure inside the source container and the vaporization chamber is preferably within a range of 1 Pa to 10,000 Pa.

Here, examples of materials for the substrate placed in the deposition reaction section include silicon; ceramics such as silicon nitride, titanium nitride, tantalum nitride, titanium oxide, ruthenium oxide, zirconium oxide, hafnium oxide, and lanthanum oxide; glass; and metals such as metallic cobalt and metallic ruthenium. The substrate may have a plate-like, spherical, fibrous, or scale-like shape. The substrate surface may be flat or may have a three-dimensional structure such as a trench structure.

(Precursor thin film formation process)
In the precursor thin film formation step, a precursor thin film is formed on the surface of the substrate by depositing an yttrium compound represented by the general formula (1) or (2) in a source gas introduced into a deposition reaction section in which a substrate is placed on the surface of the substrate. At this time, heat may be applied by heating the substrate or the deposition reaction section. The manufacturing conditions for forming the precursor thin film are not particularly limited, and for example, the reaction temperature (substrate temperature), reaction pressure, deposition rate, etc. can be appropriately determined depending on the type of thin film-forming raw material. The reaction temperature is preferably 100°C or higher, which is a temperature at which the thin film-forming raw material of the present invention reacts sufficiently, and more preferably 100°C to 400°C. The reaction pressure is preferably 1 Pa to 10,000 Pa, and more preferably 10 Pa to 1,000 Pa.

The deposition rate can be controlled by adjusting the supply conditions of the thin-film-forming raw materials (vaporization temperature, vaporization pressure), reaction temperature, and reaction pressure. A high deposition rate can result in poor thin-film properties, while a low rate can cause productivity problems. Therefore, a rate of 0.01 nm/min to 100 nm/min is preferred, with 0.1 nm/min to 50 nm/min being more preferred.

(Exhaust process)
After the precursor thin film is formed, the source gas that has not been deposited on the surface of the substrate is exhausted from the deposition reaction zone. Ideally, the source gas is completely exhausted from the deposition reaction zone, but complete exhaust is not always necessary. Exhaust methods include, for example, purging the deposition reaction zone system with an inert gas such as helium, nitrogen, or argon, exhausting by reducing the pressure inside the system, or a combination of these. When reducing the pressure, the degree of pressure reduction is preferably in the range of 0.01 Pa to 300 Pa, and more preferably in the range of 0.01 Pa to 100 Pa.

(Yttrium-containing thin film formation process)
In the yttrium-containing thin film formation step, after the exhaust step, a reactive gas is introduced into the deposition reaction section, and the precursor thin film, i.e., the yttrium compound represented by the general formula (1) or (2) deposited on the surface of the substrate, is reacted with the reactive gas by the action of the reactive gas or the action of the reactive gas and the action of heat, to form the yttrium-containing thin film.

The reactive gases include, for example, oxidizing gases such as oxygen, ozone, nitrogen dioxide, nitric oxide, water vapor, hydrogen peroxide, formic acid, acetic acid, and acetic anhydride; reducing gases such as hydrogen; organic amine compounds such as monoalkylamines, dialkylamines, trialkylamines, and alkylenediamines; and nitriding gases such as hydrazine and ammonia. These reactive gases may be used alone or in combination of two or more. In the thin film manufacturing method of the present invention, the reactive gas is preferably an oxidizing gas, and more preferably a gas containing oxygen, ozone, or water vapor. When an oxidizing gas is used as the reactive gas, a thin film of yttrium oxide is formed as the yttrium-containing thin film.

When heat is used to react the precursor thin film with the reactive gas, the reaction is preferably carried out at a temperature between 50°C and 500°C, and more preferably between 100°C and 400°C. Furthermore, the pressure in the deposition reaction zone during this process is preferably between 1 Pa and 10,000 Pa, and more preferably between 10 Pa and 1,000 Pa.

(Exhaust process)
After the formation of the yttrium-containing thin film, unreacted reactive gases and by-product gases are exhausted from the deposition reaction zone. Ideally, the reactive gases and by-product gases are completely exhausted from the deposition reaction zone, but this is not necessarily the case. The exhaust method and the degree of pressure reduction are the same as those in the exhaust step after the precursor thin film formation step described above.

As explained above, the source gas introduction process, precursor thin film formation process, exhaust process, yttrium-containing thin film formation process, and exhaust process are carried out in sequence. This series of operations constitutes one deposition cycle, and this cycle is repeated multiple times until a thin film of the required thickness is obtained, thereby producing an yttrium-containing thin film with the desired thickness. In thin film production methods using the ALD method, the thickness of the yttrium-containing thin film formed can be controlled by the number of cycles.

In addition, in the thin film manufacturing method of the present invention, as shown in Figures 3 and 4, energy such as plasma, light, or voltage may be applied to the deposition reaction zone, and a catalyst may be used. The timing of applying the energy and using the catalyst is not particularly limited, and may be, for example, when introducing the raw material gas in the raw material gas introduction step, when heating to form the precursor thin film, when introducing the reactive gas in the yttrium-containing thin film formation step, when reacting the reactive gas with the precursor thin film, when evacuating the system in the evacuation step, or between any of the above steps.

In addition, in the thin film manufacturing method of the present invention, after the thin film is formed, annealing may be performed in an inert atmosphere, an oxidizing atmosphere, or a reducing atmosphere to obtain better electrical properties, and a reflow process may be performed if step filling is required. In this case, the temperature is preferably 200°C to 1,000°C, and more preferably 250°C to 500°C.

By appropriately selecting other precursors, reactive gases, and manufacturing conditions, thin films produced using the thin-film-forming raw materials of the present invention can be coated onto substrates such as metals, oxide ceramics, nitride ceramics, and glass to produce the desired type of thin film. Because the thin films of the present invention 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, resistive films, diamagnetic films used in the recording layers of hard disks, and catalyst materials for polymer electrolyte fuel cells.

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.

[Production Example 1] Production of Yttrium Compound No. 1 1.78 g (3.12 mmol) of yttrium-tris-trimethylsilylamide and 5.8 g of dehydrated toluene were added to a 100 mL three-neck flask and thoroughly mixed. 2.02 g (10.92 mmol) of 5-((2-methoxyethyl)amino)-4-hepten-3-one was added dropwise to this suspension at room temperature. After stirring at 85°C for 3 hours, the solvent was removed under reduced pressure in an oil bath at ¹³⁰ °C. The resulting yttrium complex (orange viscous liquid) was placed in a flask and connected to a Kugelrohr purification apparatus. Distillation was performed at a heating temperature of 230°C and 55 Pa to obtain a yellow viscous liquid. The resulting yellow viscous liquid was confirmed to be Yttrium Compound No. 1 by 1H-NMR and ICP-AES. The analytical results of the resulting yellow viscous liquid are shown below.

(1) ^1H -NMR (heavy benzene)
0.993-1.031ppm (9H, triplet), 1.204-1.242ppm (9H, triplet), 2.118-2.1754ppm (6H, quartet), 2.183-2.240ppm (6H, quartet) artet), 3.223ppm (9H, singlet), 3.477-3.501ppm (6H, triplet), 3.690-3.721ppm (6H, triplet), 4.953ppm (3H, singlet)

(2) Elemental analysis results by ICP-AES Y: 13.9% by mass (theoretical value: 13.66% by mass), C: 55.4% by mass (theoretical value: 55.37% by mass), H: 9.8% by mass (theoretical value: 9.75% by mass), N: 6.4% by mass (theoretical value: 6.46% by mass), O: 14.5% by mass (theoretical value: 14.76% by mass)

[Production Example 2] Production of Yttrium Compound No. 3 1.57 g (2.76 mmol) of yttrium-tris-trimethylsilylamide and 5.1 g of dehydrated toluene were added to a 100 mL three-neck flask and thoroughly mixed. 2.06 g (9.66 mmol) of 5-((2-methoxyethyl)amino)-2,6-dimethyl-4-hepten-3-one was added dropwise to this suspension at room temperature. After stirring at 55°C for 5 hours, the solvent was removed under reduced pressure in an oil bath at 111°C. The resulting yttrium complex (orange viscous liquid) was placed in a flask and connected to a Kugelrohr purification apparatus. Distillation was performed at a heating temperature of 205°C and 21 Pa to obtain a yellow viscous liquid. The resulting yellow viscous liquid became a yellow solid when allowed to cool to room temperature. Analysis of the resulting yellow viscous liquid by ^1H -NMR and ICP-AES confirmed that it was yttrium compound No. 3. The analytical results of the obtained yellow viscous liquid are shown below.

(1) ^1H -NMR (heavy benzene)
1.061-1.077ppm (18H, doublet), 1.228-1.244ppm (18H, doublet), 2.403-2.505ppm (3H, septet), 2.967-3.064ppm (3H, s eptet), 3.213ppm (9H, singlet), 3.430-3.462ppm (6H, triplet), 3.802-3.834ppm (6H, triplet), 5.112ppm (3H, singlet)

(2) Elemental analysis results by ICP-AES Y: 12.3% by mass (theoretical value: 12.09% by mass), C: 58.4% by mass (theoretical value: 58.84% by mass), H: 10.3% by mass (theoretical value: 10.29% by mass), N: 5.9% by mass (theoretical value: 5.71% by mass), O: 13.1% by mass (theoretical value: 13.07% by mass)

[Production Example 3] Production of Yttrium Compound No. 6 1.41 g (2.47 mmol) of yttrium-tris-trimethylsilylamide and 6.8 g of dehydrated toluene were added to a 100 mL three-neck flask and thoroughly mixed. 2.08 g (8.65 mmol) of 2,2,6-trimethyl-5-((1-methoxy-2-propyl)amino)-4-hepten-3-one was added dropwise to this suspension at room temperature. After stirring at 53°C for 4 hours, the solvent was removed under reduced pressure in an oil bath at 115°C. The resulting yttrium complex (orange viscous substance) was placed in a flask and connected to a Kugelrohr purification apparatus. Distillation was performed at a heating temperature of 214°C and 17 Pa to obtain a yellow liquid. The resulting yellow liquid became a yellow glassy solid when allowed to cool to room temperature. Elemental analysis by ICP emission spectroscopy confirmed that the resulting product was yttrium compound No. 6.

(1) Elemental analysis results by ICP-AES Y: 10.8% by mass (theoretical value: 10.85% by mass), C: 61.7% by mass (theoretical value: 61.58% by mass), H: 10.5% by mass (theoretical value: 10.71% by mass), N: 5.2% by mass (theoretical value: 5.14% by mass), O: 11.8% by mass (theoretical value: 11.72% by mass)

[Production Example 4] Production of Yttrium Compound No. 15 1.65 g (2.90 mmol) of yttrium-tris-trimethylsilylamide and 8.0 g of dehydrated toluene were added to a 100 mL three-neck flask and thoroughly mixed. 2.02 g (10.2 mmol) of 5-amino-1-methoxy-2,2,6-trimethyl-4-hepten-3-one was added dropwise to this suspension at room temperature. After stirring at 86°C for 5 hours, the solvent was removed under reduced pressure in an oil bath at 120°C. The resulting yttrium complex (reddish-brown viscous substance) was placed in a flask and connected to a Kugelrohr purification apparatus. Distillation was performed at a heating temperature of 210°C and 23 Pa to obtain a yellow liquid. The resulting yellow liquid was allowed to cool to room temperature to obtain a yellow solid. The resulting yellow solid was confirmed to be Yttrium Compound No. 15 by ^1H -NMR and ICP-AES analysis. The analytical results of the obtained yellow solid are shown below.

(1) ^1H -NMR (heavy benzene)
0.908ppm (18H, broad), 1.393ppm (18H, singlet), 2.079ppm (3H, singlet), 3.239ppm ( 9H, singlet), 3.525ppm (6H, singlet), 5.269ppm (3H, singlet), 7.378ppm (3H, broad)

(2) Elemental analysis results by ICP-AES Y: 12.8% by mass (theoretical value: 12.83% by mass), C: 57.5% by mass (theoretical value: 57.21% by mass), H: 10.0% by mass (theoretical value: 10.03% by mass), N: 6.1% by mass (theoretical value: 6.07% by mass), O: 13.6% by mass (theoretical value: 13.86% by mass)

[Preparation Example 5] Preparation of Comparative Compound 1 2.44 g (4.28 mmol) of yttrium-tris-trimethylsilylamide and 7.9 g of dehydrated toluene were added to a 100 mL three-neck flask and mixed thoroughly. 1.91 g (15.0 mmol) of 5-amino-4-hepten-3-one was added dropwise to this suspension at room temperature. After stirring at 87°C for 3 hours, the solvent was removed under reduced pressure in an oil bath at 111°C. The resulting yttrium complex (orange viscous liquid) was placed in a flask and connected to a Kugelrohr purification apparatus. Distillation was performed at a heating temperature of 215°C and 50 Pa to obtain a yellow viscous liquid. The resulting yellow viscous liquid was allowed to cool to room temperature to obtain a yellow solid. The resulting yellow solid was analyzed by ^1H -NMR and ICP-AES, and was confirmed to be Comparative Compound 1 shown below. The analytical results of the resulting yellow solid are shown below.

(1) ^1H -NMR (heavy benzene)
0.879-0.916ppm (9H, triplet), 1.232-1.270ppm (9H, triplet), 1.919-1.976ppm (6H, quart et), 2.306-2.363ppm (6H, quartet), 5.025-5.030ppm (3H, doublet), 7.614ppm (3H, singlet)

(2) Elemental analysis results by ICP-AES Y: 18.9% by mass (theoretical value: 18.66% by mass), C: 52.8% by mass (theoretical value: 52.93% by mass), H: 9.4% by mass (theoretical value: 9.51% by mass), N: 8.7% by mass (theoretical value: 8.82% by mass), O: 10.2% by mass (theoretical value: 10.08% by mass)

The following evaluations were carried out using yttrium compounds No. 1, No. 3, No. 6, and No. 15 produced in Production Examples 1 to 5 above, and comparative compound 1.

(1) Melting Point Evaluation The state of the compound at normal pressure and 25°C was visually observed, and for solid compounds, 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 obtained chart, the melting point 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 is maximum on the curve on the low-temperature side of the peak indicating an endothermic reaction. The results are shown in Table 1.

(2) Temperature (°C) at 50% mass loss in reduced pressure TG-DTA
Measurements were performed using TG-DTA at 10 Torr, an argon flow rate of 50 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 mass of the test compound had decreased by 50% by mass was evaluated as the "temperature (°C) at which the mass of the test compound had decreased by 50% by mass in reduced pressure TG-DTA." A lower temperature (°C) at which the mass of the test compound had decreased by 50% by mass in reduced pressure TG-DTA indicates that vapor can be obtained at a lower temperature. The results are shown in Table 1.

(3) Thermal decomposition start temperature (°C)
A differential scanning calorimeter (DSC) was used to measure the temperature at a rate of 10°C/min over a scanning temperature range of 30°C to 600°C. The starting point of exothermic or endothermic events in the DSC chart was evaluated as the thermal decomposition starting temperature (°C). The results are shown in Table 1.

As can be seen from Table 1, comparative compound 1 had a thermal decomposition onset temperature of 267°C, and was poor in thermal stability, making it unsatisfactory as a raw material for forming thin films.

In contrast, yttrium compounds No. 1, No. 3, No. 6, and No. 15 had low melting points but thermal decomposition onset temperatures of 300°C or higher, demonstrating excellent thermal stability. Furthermore, these yttrium compounds exhibited a 50% mass loss in reduced-pressure TG-DTA at temperatures of approximately 230°C, demonstrating that vapor can be obtained at low temperatures. These results confirm that yttrium compounds represented by general formula (1) or (2) are useful as raw materials for forming thin films. Compound No. 6 of Example 3 had an appearance similar to water glass and lacked fluidity.

Example 5: Thin Film Production by ALD Using yttrium compound No. 15 as a thin film-forming raw material, a thin film was produced on a silicon dioxide substrate using the ALD apparatus shown in Figure 1 under the following conditions. Analysis of the thin film composition using X-ray photoelectron spectroscopy confirmed that the thin film contained yttrium oxide and that the residual carbon content was less than the detection limit of 0.01 atom%. Furthermore, measurement of the thin film thickness using X-ray reflectivity revealed that the thin film formed on the substrate was a smooth film with a thickness of 20 nm, and the film thickness obtained per cycle was approximately 0.05 nm.

(conditions)
Production method: ALD method Reaction temperature (substrate temperature): 300°C
Reactive gas: ozone (process)
A series of steps (1) to (4) below constituted one cycle, and 400 cycles were repeated.
(1) A source gas obtained by vaporizing a thin film-forming source material under conditions of a source container temperature of 200°C and a source container internal pressure of 100 Pa is introduced into a film-forming chamber, and an yttrium compound in the source gas is deposited on the substrate surface at a system pressure of 100 Pa for 10 seconds to form a precursor thin film.
(2) Undeposited source gas is purged from the system by argon purging for 15 seconds.
(3) A reactive gas is introduced into the film-forming chamber, and the precursor thin film is reacted with the reactive gas at a system pressure of 100 Pa for 10 seconds.
(4) Unreacted reactive gases and by-product gases are purged from the system by argon purging for 15 seconds.

Example 6: Thin Film Production by ALD Method Using yttrium compound No. 3 as a thin film forming source, a thin film was produced on a silicon dioxide substrate using the ALD apparatus shown in Figure 1 under the following conditions. Analysis of the thin film composition using X-ray photoelectron spectroscopy confirmed that the thin film contained yttrium oxide and that the residual carbon content was less than the detection limit of 0.01 atom%. Furthermore, measurement of the thin film thickness using X-ray reflectivity revealed that the thin film formed on the substrate was a smooth film with a thickness of 16 nm, and the film thickness obtained per cycle was approximately 0.04 nm.

(conditions)
Production method: ALD method Reaction temperature (substrate temperature): 300°C
Reactive gas: ozone (process)
A series of steps (1) to (4) below constituted one cycle, and 400 cycles were repeated.
(1) A source gas obtained by vaporizing a thin film-forming source material under conditions of a source container temperature of 200°C and a source container internal pressure of 100 Pa is introduced into a film-forming chamber, and an yttrium compound in the source gas is deposited on the substrate surface at a system pressure of 100 Pa for 10 seconds to form a precursor thin film.
(2) Undeposited source gas is purged from the system by argon purging for 15 seconds.
(3) A reactive gas is introduced into the film-forming chamber, and the precursor thin film is reacted with the reactive gas at a system pressure of 100 Pa for 10 seconds.
(4) Unreacted reactive gases and by-product gases are purged from the system by argon purging for 15 seconds.

Comparative Example 2: Production of Thin Film by ALD Method A thin film was produced on a silicon dioxide substrate under the same conditions as in Example 5, except that Comparative Compound 1 was used as the thin film-forming raw material. When the composition of the thin film was analyzed using X-ray electron spectroscopy, it was found that the thin film contained yttrium oxide, but residual carbon was detected. Furthermore, when the state of the thin film was observed using a scanning electron microscope, it was found that the thin film formed on the substrate was not smooth, and the film thickness could not be measured.

From the above, the thin film-forming raw material containing the yttrium compound of the present invention has a low melting point, can produce vapor at low temperatures, and has excellent thermal stability. Therefore, when a thin film is produced using the thin film-forming raw material of the present invention, a high-quality yttrium-containing thin film with a low amount of residual carbon can be produced.

Claims (6)

A thin film-forming material containing an yttrium compound represented by the following general formula (1) or (2):
(In the formula, ^R1 and ^R3 each independently represent an alkyl group having 1 to 4 carbon atoms, ^R2 represents a hydrogen atom , R4 represents an ethylene group or a propane-1,2-diyl group ^, and ^R5 represents a methyl group , and multiple ^R1s , ^R2s , ^R3s , ^R4s , and ^R5s may be the same or different.)
(In the formula, R ⁶ and R ⁸ each independently represent an alkyl group having 1 to 4 carbon atoms , a methoxyisopropyl group, or a methoxytert-butyl group ; R ⁷ represents a hydrogen atom ; and multiple R ^{6 s} , R ^{7 s} , and R ⁸ s may be the same or different, provided that at least one of R ^{6 s} and R ^{8 s} represents a methoxyisopropyl group or a methoxytert-butyl group .) 2. The thin film-forming material according to claim 1, comprising an yttrium compound in which ^R1 and ^R3 are isopropyl groups, ^R2 is a hydrogen atom, ^R4 is an ethylene group, and ^R5 is a methyl group in the general formula (1), or an yttrium compound in which ^R6 is a methoxy tert-butyl group, ^R7 is a hydrogen atom, and ^R8 is an isopropyl group in the general formula (2). a step of introducing a raw material gas obtained by vaporizing the thin film forming raw material according to claim 1 or 2 into a film formation chamber in which a substrate is placed;
depositing an yttrium compound in the source gas on the surface of the substrate to form a precursor thin film;
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 yttrium atoms on the surface of the substrate. 4. The method for producing a thin film according to claim 3 , wherein the reactive gas is an oxidizing gas, and the thin film containing yttrium atoms is yttrium oxide. 5. The method for producing a thin film according to claim 4 , wherein the oxidizing gas is a gas containing oxygen, ozone, or water vapor. The method for producing a thin film according to any one of claims 3 to 5 , wherein the precursor thin film and the reactive gas are reacted at a temperature in the range of 100°C to 400°C.