Method for producing yttrium oxide-containing film

Abstract

The present invention is a method for producing a yttrium oxide-containing film by means of an atomic layer deposition method, said method for producing a yttrium oxide-containing film comprising: a step wherein a starting material gas obtained by vaporizing a thin film forming starting material that contains tris(sec-butylcyclopentadienyl)yttrium is introduced into a processing atmosphere, thereby having the tris(sec-butylcyclopentadienyl)yttrium deposit on a base material; and a step wherein yttrium is oxidized by causing the tris(sec-butylcyclopentadienyl)yttrium deposited on the base material and a reactive gas that contains a gas selected from the group consisting of oxygen plasma, ozone, ozone plasma and mixtures thereof to react with each other in the processing atmosphere.

Description

[Technical field]

[0001] The present invention relates to a method for producing an yttrium oxide-containing film by atomic layer deposition. [Background technology]

[0002] It is known that a yttrium oxide film has high heat resistance, plasma resistance and optical transparency, and can be used as a heat-resistant protective film, a plasma-resistant protective film, an optical thin film, and the like.

[0003] Examples of methods for producing the above-mentioned thin films include sputtering, ion plating, MOD methods such as coating pyrolysis and sol-gel methods, CVD, atomic layer deposition (hereinafter referred to as "ALD"), which is a type of CVD, etc. Among these, the ALD method is mainly used because it has many advantages such as excellent composition controllability and step coverage, suitability for mass production, and the possibility of hybrid integration.

[0004] Patent Document 1 discloses a method for producing an yttrium oxide film by an ALD method, using tris(sec-butylcyclopentadienyl)yttrium as a thin film forming raw material and water vapor as a reactive gas.

[0005] Patent Document 2 discloses a method for producing an yttrium oxide film by a CVD method using tris(sec-butylcyclopentadienyl)yttrium as a thin film forming raw material and oxygen gas as a reactive gas.

[0006] Non-Patent Document 1 discloses a method for producing an yttrium oxide film by the ALD method, using tris(isopropylcyclopentadienyl)yttrium as a thin film forming raw material and ozone as a reactive gas. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2018-168398 A [Patent Document 2] JP 2008-274374 A [Non-patent literature]

[0008] [Non-Patent Document 1] ECS Transactions,50(13)107-116(2012),@The Electrochemical Society, “Growth Characteristics and Properties of Yttrium Oxide Thin Films by Atomic Layer Deposition from Novel Y(iPrCp)3 Precursor and O3” Summary of the Invention [Problem to be solved by the invention]

[0009] In the production of yttrium oxide films by the ALD method, it is necessary to exhaust unreacted reactive gas and by-product gas after reacting the yttrium compound deposited on the substrate with a reactive gas. However, in the method described in Patent Document 1, which uses water vapor as a reactive gas, there is a problem that it takes a long time to exhaust water vapor. In addition, when the cycle time of film formation is shortened in a state where the exhaust of water vapor is insufficient, there is a problem that carbon compounds derived from the by-product gas remain in the obtained yttrium oxide film, and a high-quality film cannot be obtained.

[0010] In addition, when oxygen gas is used as the reactive gas, the reaction between the thin film forming raw material and the reactive gas must be carried out at high temperature. In the production of an yttrium oxide film by a CVD method using tris(sec-butylcyclopentadienyl)yttrium as the thin film forming raw material and oxygen gas as the reactive gas described in Patent Document 2, oxygen gas at 400°C is used and reacted with tris(sec-butylcyclopentadienyl)yttrium at 600°C, but there was a problem that the damage to the substrate was significant due to the high temperature reaction. In addition, when the raw material and oxygen gas are reacted at a lowered temperature, there was a problem that the reactivity of the oxygen gas was reduced and carbon remained in the yttrium oxide film.

[0011] Furthermore, as described in Non-Patent Document 1, when tris(isopropylcyclopentadienyl)yttrium is used as a thin film forming raw material for the ALD method, it is a solid compound at room temperature, so it needs to be heated to make it liquid before being introduced into the ALD apparatus. In addition, it is necessary to heat the entire piping of the ALD apparatus so that tris(isopropylcyclopentadienyl)yttrium does not solidify, and complicated production management is required.

[0012] Therefore, an object of the present invention is to provide a method for producing an yttrium oxide-containing film by an ALD method, which can produce a high-quality yttrium oxide film even if the cycle time of film formation is shortened by using a thin film-forming raw material that does not require complicated production management. [Means for solving the problem]

[0013] As a result of intensive research, the present inventors have discovered a method for producing an yttrium oxide-containing film by an ALD method, which uses a thin film-forming raw material that does not require complicated production management, and which can achieve both a significant reduction in the film formation cycle time and the production of a high-quality yttrium oxide film, and have completed the present invention.

[0014] That is, the present invention relates to a method for producing an yttrium oxide-containing film on a substrate by an ALD method, and provides a method for producing an yttrium oxide-containing film, comprising: step (A): introducing a raw material gas obtained by vaporizing a thin film forming raw material containing tris(sec-butylcyclopentadienyl)yttrium into a processing atmosphere, and depositing tris(sec-butylcyclopentadienyl)yttrium on the substrate (hereinafter referred to as "step (A)"); and step (B): reacting the tris(sec-butylcyclopentadienyl)yttrium deposited on the substrate with a reactive gas containing a gas selected from the group consisting of oxygen plasma, ozone, ozone plasma, and mixtures thereof in the processing atmosphere, to oxidize yttrium (hereinafter referred to as "step (B)").

[0015] In the production method of the present invention, the temperature of the substrate in step (B) is preferably in the range of 150°C to 400°C.

[0016] Furthermore, in the manufacturing method of the present invention, the pressure of the treatment atmosphere when reacting the reactive gas with tris(sec-butylcyclopentadienyl)yttrium deposited on the substrate in step (B) is preferably in the range of 0.1 Pa to 10,000 Pa.

[0017] In addition, the manufacturing method of the present invention preferably includes a step of exhausting the gas in the processing atmosphere at least one of between the step (A) and the step (B) and after the step (B).

[0018] Furthermore, in the production method of the present invention, it is preferable to repeat a film formation cycle including steps (A) and (B) in this order. Effect of the Invention

[0019] According to the present invention, by using a thin film forming raw material containing tris(sec-butylcyclopentadienyl)yttrium which is liquid at room temperature, there is no need to heat the raw material and the piping in the ALD apparatus before introducing it into the apparatus. In addition, according to the present invention, by using a reactive gas containing a gas selected from the group consisting of oxygen plasma, ozone, ozone plasma, and a mixture thereof, the time of the exhaust step performed after the step (B) can be shortened compared to the case where water vapor is used as the reactive gas. Therefore, the cycle time of film formation can be significantly shortened without performing complicated production management, and a high-quality yttrium oxide-containing film with little residual carbon can be produced with good productivity. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram showing an example of an ALD apparatus used in the method for producing an yttrium oxide-containing film according to the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing another example of an ALD apparatus used in the method for producing an yttrium oxide-containing film according to the present invention. [Diagram 3] FIG. 3 is a schematic diagram showing yet another example of an ALD apparatus used in the method for producing an yttrium oxide-containing film according to the present invention. [Figure 4] FIG. 4 is a schematic diagram showing yet another example of an ALD apparatus used in the method for producing an yttrium oxide-containing film according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The production method of the present invention can use the same procedure as the well-known general ALD method, but the present invention is characterized in that the yttrium oxide-containing film is produced by combining the steps (A) and (B) described below.

[0022] The step (A) in the manufacturing method of the present invention is a step of introducing a raw material gas obtained by vaporizing a thin film forming raw material containing tris(sec-butylcyclopentadienyl)yttrium into a processing atmosphere, and depositing tris(sec-butylcyclopentadienyl)yttrium on a substrate. Here, "deposition" represents a concept including the adsorption of tris(sec-butylcyclopentadienyl)yttrium on a substrate. Tris(sec-butylcyclopentadienyl)yttrium is a liquid compound at room temperature, and therefore is a compound with excellent handling properties. Therefore, by using a thin film forming raw material containing tris(sec-butylcyclopentadienyl)yttrium, it is not necessary to heat the raw material and the piping in the ALD apparatus before introducing it into the ALD apparatus, and therefore it is possible to form an yttrium oxide-containing film without the need for complicated production management.

[0023] When a raw material gas obtained by vaporizing a thin film formation raw material containing the above-mentioned tris(sec-butylcyclopentadienyl)yttrium is introduced into a film formation chamber (processing atmosphere) of an ALD apparatus, the raw material gas preferably contains tris(sec-butylcyclopentadienyl)yttrium at 90 vol % or more, and more preferably at 99 vol % or more.

[0024] Here, the method for producing tris(sec-butylcyclopentadienyl)yttrium used in the present invention is not particularly limited, and it can be produced by applying a well-known reaction. For example, it can be synthesized by a salt exchange reaction between an alkali metal complex such as sec-butylcyclopentadienyl sodium or sec-butylcyclopentadienyl potassium and a halide such as yttrium trichloride or tribromide.

[0025] In the method for producing an yttrium oxide-containing film by the ALD method of the present invention, the thin film forming raw material may contain tris(sec-butylcyclopentadienyl)yttrium and be a precursor of the thin film, and the composition varies depending on the type of the target thin film. For example, when producing a thin film containing only yttrium as a metal, the thin film forming raw material of the present invention does not contain metal compounds and metalloid compounds other than yttrium. On the other hand, when producing a thin film containing yttrium and a metal and / or metalloid other than yttrium, the thin film forming raw material of the present invention can contain a compound containing a desired metal and / or a compound containing a metalloid (hereinafter referred to as "other precursors") in addition to tris(sec-butylcyclopentadienyl)yttrium.

[0026] In addition, in a multi-component ALD method using a plurality of precursors, other precursors that can be used together with tris(sec-butylcyclopentadienyl)yttrium are not particularly limited, and any well-known precursor that is used as a thin film formation raw material in the ALD method can be used.

[0027] Examples of the other precursor include compounds of silicon or a metal and 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, scandium, ruthenium, yttrium, lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium.

[0028] Examples of the alcohol compounds 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.

[0029] 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.

[0030] Examples of the β-diketone compound used as the organic ligand of 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-6 fluorine-substituted alkyl β-diketones such as 1,1,1-trifluoropentane-2,4-dione, 1,1,1-trifluoro-5,5-dimethylhexane-2,4-dione, 1,1,1,5,5,5-hexafluoropentane-2,4-dione, 1,3-diperfluorohexylpropane-1,3-dione; and ether-substituted β-diketones such as 1,1,5,5-tetramethyl-1-methoxyhexane-2,4-dione, 2,2,6,6-tetramethyl-1-methoxyheptane-3,5-dione, 2,2,6,6-tetramethyl-1-(2-methoxyethoxy)heptane-3,5-dione.

[0031] Examples of the cyclopentadiene compound used as the organic ligand of the other precursor include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, propylcyclopentadiene, isopropylcyclopentadiene, butylcyclopentadiene, sec-butylcyclopentadiene, isobutylcyclopentadiene, tert-butylcyclopentadiene, dimethylcyclopentadiene, tetramethylcyclopentadiene, and pentamethylcyclopentadiene. Examples of the organic amine compound used as the organic ligand include methylamine, ethylamine, propylamine, isopropylamine, butylamine, sec-butylamine, tert-butylamine, isobutylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, ethylmethylamine, propylmethylamine, and isopropylmethylamine.

[0032] The above-mentioned other precursors are known in the art, and their manufacturing methods are also 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. Here, examples of the inorganic salt of the metal or its hydrate include metal halides and nitrates, and examples of the alkali metal alkoxide include sodium alkoxide, lithium alkoxide, potassium alkoxide, and the like.

[0033] In addition, in the multi-component ALD method as described above, there are a method in which each component of the thin film formation material is vaporized and supplied independently (hereinafter, sometimes referred to as a "single source method"), and a method in which a mixed material in which multi-component materials are mixed in advance with a desired composition is vaporized and supplied (hereinafter, sometimes referred to as a "cocktail source method").

[0034] In the case of the single source method, the other precursor is preferably a compound having similar thermal and / or oxidative decomposition behavior to tris(sec-butylcyclopentadienyl)yttrium. In the case of the cocktail source method, the other precursor is preferably one that has similar thermal and / or oxidative decomposition behavior to tris(sec-butylcyclopentadienyl)yttrium and does not undergo deterioration due to chemical reactions or the like when mixed.

[0035] In the case of the cocktail source method, a mixture of tris(sec-butylcyclopentadienyl)yttrium and other precursors, or a mixed solution obtained by dissolving the mixture in an organic solvent, can be used as a thin film forming raw material.

[0036] The organic solvent is not particularly limited, and any well-known organic solvent can be used. Examples of the organic solvent include acetates such as ethyl acetate, butyl acetate, and methoxyethyl acetate; ethers such as tetrahydrofuran, tetrahydropyran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, dibutyl ether, and dioxane; ketones such as methyl butyl ketone, methyl isobutyl ketone, ethyl butyl ketone, dipropyl ketone, diisobutyl ketone, methyl amyl ketone, cyclohexanone, and methylcyclohexanone; hydrocarbons such as hexane, cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, heptane, octane, toluene, and xylene; hydrocarbons having a cyano group such as 1-cyanopropane, 1-cyanonobutane, 1-cyanohexane, cyanocyclohexane, cyanobenzene, 1,3-dicyanopropane, 1,4-dicyanobutane, 1,6-dicyanohexane, 1,4-dicyanocyclohexane, and 1,4-dicyanobenzene; pyridine, lutidine, and the like. These organic solvents may be used alone or in combination of two or more depending on the solubility of the solute, the relationship between the use temperature and the boiling point, the flash point, and the like.

[0037] In the manufacturing method of the present invention, when a solution of tris(sec-butylcyclopentadienyl)yttrium and an organic solvent is used as a thin film forming raw material, it is preferable to add the organic solvent so that the total amount of precursors in the thin film forming raw material is 0.01 mol / L to 2.0 mol / L, particularly 0.05 mol / L to 1.0 mol / L.

[0038] Here, the total amount of precursors refers to the total amount of tris(sec-butylcyclopentadienyl)yttrium and other precursors containing yttrium when the thin film forming raw material does not contain any metal compound or metalloid compound other than yttrium, and refers to the total amount of tris(sec-butylcyclopentadienyl)yttrium and other precursors when the thin film forming raw material contains other precursors other than tris(sec-butylcyclopentadienyl)yttrium.

[0039] In addition, the above-mentioned thin film forming raw material may contain a nucleophilic reagent, if necessary, in order to improve the stability of tris(sec-butylcyclopentadienyl)yttrium and other precursors. Examples of the nucleophilic reagent include ethylene glycol ethers such as glyme, diglyme, triglyme, and tetraglyme, crown ethers such as 18-crown-6, dicyclohexyl-18-crown-6, 24-crown-8, dicyclohexyl-24-crown-8, and dibenzo-24-crown-8, ethylenediamine, N,N'-tetramethylethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, 1,1,4,7,7-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetramine, Examples of the nucleophilic reagent 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, more preferably in the range of 1 mol to 4 mol, relative to 1 mol of the total amount of the precursor.

[0040] It is desirable that the thin film forming raw material used in the manufacturing method of the present invention contains 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 elements are preferably 100 ppb or less per element, more preferably 10 ppb or less, and the total amount 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 of an LSI, it is necessary to reduce the content of alkali metal elements and alkaline earth metal elements that affect the electrical properties of the resulting thin film. The impurity halogens are preferably 100 ppm or less, more preferably 10 ppm or less, and even more preferably 1 ppm or less. The impurity organic components are preferably 500 ppm or less in total, more preferably 50 ppm or less, and even more preferably 10 ppm or less. In addition, since moisture is a cause of particle generation in the thin film forming raw materials and during thin film formation, it is better 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, more preferably 1 ppm or less.

[0041] In the manufacturing method of the present invention, it is preferable that the thin film forming raw material contains as few particles as possible in order to reduce or prevent particle contamination of the thin film to be formed. Specifically, in particle measurement in the liquid phase using a light scattering type liquid-borne particle detector, it is preferable that the number of particles larger than 0.3 μm is 100 or less per 1 ml of liquid phase, and it is more preferable that the number of particles larger than 0.2 μm is 100 or less per 1 ml of liquid phase.

[0042] As an apparatus used in the manufacturing method of the yttrium oxide-containing film of the present invention using the above-mentioned thin film forming raw material, a well-known ALD apparatus can be used. Specific examples of the apparatus include an apparatus capable of bubbling and supplying a precursor as shown in Figures 1 and 3, and an apparatus having a vaporization chamber as shown in Figures 2 and 4. In addition, an apparatus capable of performing plasma treatment on a reactive gas as shown in Figures 3 and 4 can be used. Not limited to the single-wafer type apparatus equipped with a film formation chamber as shown in Figures 1 to 4, an apparatus capable of simultaneously processing multiple wafers using a batch furnace can also be used.

[0043] In the production method of the present invention, the method of introducing the source gas obtained by vaporizing the thin film forming source material in the step (A) into the processing atmosphere includes a gas transport method in which the thin film forming source material for the ALD method is vaporized into vapor by heating and / or reducing the pressure in a container (hereinafter referred to as a "source material container") in which the thin film forming source material is stored, and then introduced into a film formation chamber (processing atmosphere) in which a substrate is placed, together with a carrier gas such as argon, nitrogen, or helium as necessary; and a liquid transport method in which the thin film forming source material is transported in a liquid or solution state to a vaporization chamber, vaporized in the vaporization chamber by heating and / or reducing the pressure, and then introduced into the film formation chamber.

[0044] In the case of the gas transportation method, tris(sec-butylcyclopentadienyl)yttrium itself can be used as a thin film forming raw material. In the case of the liquid transport method, tris(sec-butylcyclopentadienyl)yttrium is liquid at room temperature and can be used as it is as a thin film formation raw material, but a solution of tris(sec-butylcyclopentadienyl)yttrium mixed with an organic solvent can also be used as a thin film formation raw material.

[0045] In the manufacturing method of the present invention, the method for vaporizing the thin film forming raw material containing tris(sec-butylcyclopentadienyl)yttrium in the step (A) is not particularly limited, and can be performed by a method for vaporizing an organometallic compound used in a well-known general ALD method. For example, the vaporization can be performed by heating and / or reducing pressure in a raw material container of the ALD apparatus shown in FIG.

[0046] The material of the substrate placed in the film formation chamber may be, for example, silicon, ceramics such as indium arsenide, indium gallium arsenide, silicon oxide, silicon nitride, boron nitride, silicon carbide, aluminum oxide, aluminum nitride, tantalum oxide, tantalum nitride, titanium oxide, titanium nitride, titanium carbide, ruthenium oxide, zirconium oxide, hafnium oxide, lanthanum oxide, and gallium nitride, glass, platinum, ruthenium, aluminum, copper, nickel, cobalt, tungsten, molybdenum, stainless steel, or alloys thereof. The surface of the substrate may be coated.

[0047] The shape of the substrate may be plate-like, spherical, fibrous, scaly, or particulate (particularly fine particles). The substrate surface may be flat or may have a three-dimensional structure such as a trench structure.

[0048] Step (B) in the manufacturing method of the present invention is a step of reacting tris(sec-butylcyclopentadienyl)yttrium deposited on a substrate with a reactive gas containing a gas selected from the group consisting of oxygen plasma, ozone, ozone plasma, and mixtures thereof in a treatment atmosphere to oxidize the yttrium.

[0049] The reactive gas in this step contains a gas selected from the group consisting of oxygen plasma, ozone, ozone plasma, and mixtures thereof. By using these gases as the reactive gas, the gases are more easily exhausted from the treatment atmosphere than when water vapor is included, and therefore the time required for the exhaust step can be shortened.

[0050] The reactive gas may be generated outside the deposition chamber and introduced into the deposition chamber, or oxygen gas or ozone gas may be converted into plasma in the deposition chamber using an ALD apparatus as shown in Figures 3 and 4. The method for generating oxygen plasma, ozone, and ozone plasma and the method for introducing them into the deposition chamber are not particularly limited, and any method used in a well-known general ALD method may be used.

[0051] The reactive gas may be a single gas or a mixed gas with argon, nitrogen, oxygen, hydrogen, etc. In the case of a mixed gas, the concentration of a gas selected from the group consisting of oxygen plasma, ozone, ozone plasma, and mixtures thereof in the mixed gas is preferably within a range of 0.01% to 50% by volume, more preferably 0.1% to 20% by volume, and further preferably 1.0% to 15% by volume.

[0052] In step (B), the water content in the reactive gas is preferably 0.1% by mass or less, and more preferably 0.01% by mass or less.

[0053] The yttrium oxide-containing film obtained by the manufacturing method of the present invention may be a thin film containing 5 mass % or more of yttrium oxide, and examples thereof include yttrium oxide, yttria-stabilized zirconia, yttrium orthovanadate, yttrium dioxide sulfide, yttrium-barium-copper oxide, yttrium aluminate, etc. Among these, the manufacturing method of the present invention is suitable as a method for manufacturing an yttrium oxide film.

[0054] For example, a method for producing an yttrium oxide-containing film on a silicon substrate by the production method of the present invention will be described below. Here, the ALD apparatus shown in FIG. 1 is used.

[0055] First, a silicon substrate is placed in a film-forming chamber. The method of placing the silicon substrate is not particularly limited, and the substrate may be placed in the film-forming chamber by a well-known method. Tris(sec-butylcyclopentadienyl)yttrium is vaporized in a source container. In this case, the temperature of the source container is preferably in the range of 20°C to 200°C. Next, a source gas containing the vaporized tris(sec-butylcyclopentadienyl)yttrium is introduced into the film-forming chamber and deposited (adsorbed) on a silicon substrate heated to preferably 20°C to 400°C, more preferably 150°C to 250°C (step (A)).

[0056] The pressure in the deposition chamber when tris(sec-butylcyclopentadienyl)yttrium is introduced into the deposition chamber in the step (A) is in the range of 0.1 Pa to 10,000 Pa, preferably 1 Pa to 1,000 Pa, and more preferably 10 Pa to 500 Pa.

[0057] Next, tris(sec-butylcyclopentadienyl)yttrium that has not been deposited on the silicon substrate is exhausted from the deposition chamber (exhaust step 1). Ideally, tris(sec-butylcyclopentadienyl)yttrium that has not been deposited on the silicon substrate is completely exhausted from the deposition chamber, but it is not necessarily required to completely exhaust it. Exhaust methods include a method of purging the system with an inert gas such as helium or argon, a method of exhausting by reducing the pressure inside the system, and a combination of these methods. When reducing the pressure, the degree of reduction in pressure is preferably 0.01 Pa to 300 Pa, more preferably 0.1 Pa to 150 Pa.

[0058] Next, the tris(sec-butylcyclopentadienyl)yttrium deposited on the silicon substrate is reacted with a reactive gas containing a gas selected from the group consisting of oxygen plasma, ozone, ozone plasma, and a mixture thereof in a film formation chamber to oxidize the yttrium (step (B)). The temperature of the substrate when heat is applied in this step is preferably in the range of 150°C to 400°C at which tris(sec-butylcyclopentadienyl)yttrium vapor is obtained, more preferably in the range of 150°C to 300°C, and even more preferably in the range of 150°C to 250°C. The difference between the substrate temperature in step (A) and the substrate temperature when heat is applied in step (B) is preferably in the range of 0°C to 20°C in absolute value. This is because by adjusting the temperature within this range, the effect of making the yttrium oxide-containing film less likely to warp is observed. However, even if the temperature of the substrate is less than 150° C., it is possible to form an yttrium oxide-containing film derived from tris(sec-butylcyclopentadienyl)yttrium.

[0059] The pressure of the treatment atmosphere when reacting the reactive gas with tris(sec-butylcyclopentadienyl)yttrium in the step (B) is in the range of 0.1 Pa to 10,000 Pa, preferably 1 Pa to 1,000 Pa, and more preferably 10 Pa to 500 Pa. By adjusting the pressure within this range, a high-quality thin film containing no residual carbon can be obtained.

[0060] Next, unreacted reactive gas and by-produced gas are exhausted from the deposition chamber (exhaust step 2). Ideally, unreacted reactive gas and by-produced gas are completely exhausted from the deposition chamber, but it is not necessary to exhaust them completely. Exhaust methods include a method of purging the system with an inert gas such as helium or argon, a method of exhausting by reducing the pressure inside the system, and a combination of these methods. When reducing the pressure, the degree of reduction is preferably 0.01 Pa to 300 Pa, more preferably 0.1 Pa to 150 Pa.

[0061] A series of operations consisting of the above-mentioned step (A), evacuation step 1, step (B), and evacuation step 2 constitutes one cycle, and this cycle may be repeated multiple times until an yttrium oxide-containing film having a required thickness is obtained.

[0062] In the manufacturing method of the present invention, energy such as plasma, light, voltage, etc. may be further applied. The timing of applying such energy is not particularly limited, and may be, for example, when tris(sec-butylcyclopentadienyl)yttrium is vaporized and introduced into the film formation chamber in the (A) step, when the system is evacuated in the evacuation step, or between the above steps.

[0063] In the manufacturing method of the present invention, after the thin film deposition, an annealing treatment may be performed in an inert gas atmosphere or a reducing gas atmosphere in order to obtain better film quality, and a reflow process may be performed if step filling is required. The temperature in this case is 400°C to 1,200°C, and preferably 500°C to 800°C. EXAMPLES

[0064] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0065] Example 1 Using tris(sec-butylcyclopentadienyl)yttrium (manufactured by ADEKA Corporation, product name "Y-5000") as a thin film forming raw material, an yttrium oxide-containing film was produced on a silicon wafer under the ALD method conditions described below using the ALD apparatus shown in Figure 1. When the thin film composition of the obtained thin film was confirmed by X-ray photoelectron spectroscopy, the obtained thin film was found to be yttrium oxide, and no residual carbon was detected. The time required for one cycle of the series of steps (1) to (4) was 25.2 seconds.

[0066] (ALD method conditions) Reaction temperature (silicon wafer temperature): 200°C Reactive gas: Ozone A series of steps consisting of the following steps (1) to (4) was defined as one cycle, and 50 cycles were repeated. (1) A thin film forming source material (hereinafter referred to as "source gas") vaporized under the conditions of source container temperature: 180°C, source container internal pressure: 100 Pa is introduced into a film formation chamber and deposited at a system pressure of 100 Pa for 5 seconds. (2) Undeposited source gas is removed by argon purging for 10 seconds. (3) The reactive gas is introduced into the deposition chamber and reacted at a system pressure of 100 Pa for 0.2 seconds. (4) Unreacted reactive gases and by-product gases are removed by purging with argon for 10 seconds.

[0067] Comparative Example 1 An yttrium oxide-containing film was produced in the same manner as in Example 1, except that the reactive gas was changed to water vapor. The composition of the obtained thin film was confirmed by X-ray photoelectron spectroscopy, and it was found that the obtained thin film was yttrium oxide and had a residual carbon content of 1.8 mass %. The time required for one cycle of the series of steps (1) to (4) was 25.2 seconds.

[0068] Comparative Example 2 An yttrium oxide-containing film was produced in the same manner as in Comparative Example 1, except that the thin film forming raw material was changed from tris(sec-butylcyclopentadienyl)yttrium to tris(isopropylcyclopentadienyl)yttrium. When the thin film composition of the obtained thin film was confirmed by X-ray photoelectron spectroscopy, the obtained thin film was yttrium oxide, and the residual carbon was 5.6 mass %. The time required for one cycle of the series of steps (1) to (4) was 25.2 seconds.

[0069] Comparative Example 3 An yttrium oxide-containing film was produced in the same manner as in Example 1, except that the reactive gas was changed to oxygen gas. The composition of the obtained thin film was confirmed by X-ray photoelectron spectroscopy, and it was found that the obtained thin film was yttrium oxide with a residual carbon content of 0.8 mass%. The time required for one cycle of the series of steps (1) to (4) was 25.2 seconds.

[0070] Comparative Example 4 An yttrium oxide-containing film was produced in the same manner as in Comparative Example 1, except that the argon purging time in step (4) was changed from 10 seconds to 60 seconds. When the thin film composition of the obtained thin film was confirmed by X-ray photoelectron spectroscopy, the obtained thin film was yttrium oxide, and no residual carbon was detected. The time required for one cycle of the series of steps (1) to (4) was 75.2 seconds.

[0071] Comparative Example 5 An yttrium oxide-containing film was produced in the same manner as in Comparative Example 4, except that the argon purging time in step (2) was changed from 10 seconds to 30 seconds. When the thin film composition of the obtained thin film was confirmed by X-ray photoelectron spectroscopy, the obtained thin film was yttrium oxide, and no residual carbon was detected. The time required for one cycle of the series of steps (1) to (4) was 95.2 seconds.

[0072] [Table 1]

[0073] From Comparative Example 1, when the reactive gas was water vapor, the purge time of 10 seconds was insufficient, residual carbon was detected in the yttrium oxide-containing film, and a good-quality thin film could not be produced. Also, from Comparative Example 2, when tris(isopropylcyclopentadienyl)yttrium was used as the thin-film forming raw material and the reactive gas was water vapor, the purge time of 10 seconds was insufficient, residual carbon was detected in the yttrium oxide-containing film, and a good-quality thin film could not be produced.

[0074] In Comparative Examples 4 and 5, when tris(sec-butylcyclopentadienyl)yttrium was used as the thin film forming raw material, even if water vapor was used as the reactive gas, no residual carbon was detected in the obtained thin film if the argon purge time was sufficiently secured. However, the productivity of the yttrium oxide-containing film was not satisfactory due to the long cycle time.

[0075] In contrast to these, from Example 1, it was confirmed that when tris(sec-butylcyclopentadienyl)yttrium was used as a thin film forming raw material, and a gas selected from the group consisting of oxygen plasma, ozone, ozone plasma, and mixtures thereof was used as a reactive gas to produce an yttrium oxide-containing film by the ALD method, the cycle time was significantly shortened to improve productivity, and a high-quality yttrium oxide-containing film with no detectable residual carbon could be produced.

Claims

1. Step (A): introducing a source gas obtained by vaporizing a thin film forming source material containing tris(sec-butylcyclopentadienyl)yttrium into a processing atmosphere to deposit tris(sec-butylcyclopentadienyl)yttrium on a substrate; (B) step: reacting tris(sec-butylcyclopentadienyl)yttrium deposited on the substrate with a reactive gas containing a gas selected from the group consisting of oxygen plasma, ozone, ozone plasma, and mixtures thereof in a treatment atmosphere to oxidize yttrium, The raw material gas contains 99% by volume or more of tris(sec-butylcyclopentadienyl)yttrium, The method for producing an yttrium oxide-containing film, wherein the reactive gas does not contain water vapor.

2. 2. The method for producing an yttrium oxide-containing film according to claim 1, wherein the temperature of the substrate in the step (B) is in the range of 150° C. to 400° C.

3. The method for producing an yttrium oxide-containing film according to claim 1 or 2, wherein the pressure of the treatment atmosphere when reacting the tris(sec-butylcyclopentadienyl)yttrium deposited on the substrate with the reactive gas in the step (B) is in the range of 0.1 Pa to 10,000 Pa.

4. The method for producing an yttrium oxide-containing film according to any one of claims 1 to 3, further comprising a step of exhausting the gas in the treatment atmosphere at least one of between the step (A) and the step (B) and after the step (B).

5. The method for producing an yttrium oxide-containing film according to any one of claims 1 to 4, wherein a film formation cycle including the steps (A) and (B) is repeated in this order.

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