WO2021054160A1 - Raw material for forming thin film for atomic layer deposition and method for producing zinc-containing thin film using same - Google Patents

Abstract

The present invention provides: a raw material for forming a thin film for atomic layer deposition that contains a zinc compound represented by general formula (1) (in the formula, R¹ and R² each independently represent an alkyl group having 1-5 carbon atoms, a trimethylsilyl group, or a trifluoromethyl group, and R¹ and R² are different groups); and a method for producing a zinc-containing thin film by atomic layer deposition including a step in which a raw material gas obtained by vaporizing the raw material for forming a thin film is introduced into a processing atmosphere, the zinc compound within the raw material gas is deposited on the surface of a substrate, and a precursor layer is formed and a step in which a reactive gas is introduced into the processing atmosphere and the precursor layer and the reactive gas are made to react.

Description

Thin film forming raw material for atomic layer deposition and method for producing zinc-containing thin film using it

The present invention relates to a thin film forming raw material for an atomic layer deposition method containing a zinc compound having a specific structure, and a method for producing a zinc-containing thin film using the same.

Zinc is used as a component for forming a compound semiconductor, and various compounds have been reported as a thin film forming raw material for producing a thin film containing zinc.

Examples of the thin film manufacturing method include a MOD method such as a sputtering method, an ion plating method, a coating pyrolysis method and a sol-gel method, and a CVD method. Among these, the atomic layer deposition method (hereinafter referred to as “the atomic layer deposition method”), which is one of the CVD methods, has many advantages such as excellent composition controllability and step covering property, suitable for mass production, and hybrid integration. The "ALD method") is the optimal manufacturing process.

Various raw materials that can be used for vapor phase thin film forming methods such as the CVD method and the ALD method have been reported, but the thin film forming raw materials that can be applied to the ALD method have a sufficiently wide temperature region called the ALD window. It is necessary to have. It is common general knowledge in the technical field that even a thin film forming raw material that can be used in the CVD method is often not suitable for the ALD method.

In the method for producing a metal-containing thin film, for example, Patent Document 1 proposes a large number of metal compounds such as bis (di-tert-butylamino) zinc as a thin film forming raw material for a metal oxide that coats a substrate. Patent Document 2 uses a ZnSe film using a zinc raw material such as a triethylamine adduct of dimethylzinc, diethylzinc, or dimethylzinc and a raw material for MOCVD containing a product produced by reacting ammonia, primary or secondary amine. Is disclosed to form. Non-Patent Document 1 discloses that an alkyl (dialkylamide) zinc compound is used as a zinc precursor and a thin film is produced by a MOCVD method.

Japanese Patent No. 5290488 Japanese Unexamined Patent Publication No. 10-51031

In addition to having a wide ALD window, the thin film forming raw material used in the ALD method is required to have a low melting point, high volatility, react with a reactive gas at a low temperature, and produce a thin film with high productivity. .. However, although Patent Document 1 contains a description regarding the ALD method, it does not specifically describe the application of a zinc compound to the ALD method. Patent Document 2 and Non-Patent Document 1 disclose various zinc amide compounds as zinc raw materials for ZnSe thin films. However, although these documents disclose a method for producing a zinc-containing thin film using a zinc amide compound as a raw material for MOCVD, they do not disclose the production of a zinc-containing thin film using the ALD method.

Therefore, the present invention uses a thin film forming raw material containing a zinc compound, which has a low melting point, is highly volatile, and is suitable as a raw material used in the ALD method capable of reacting with a reactive gas at a low temperature, and using the same. An object of the present invention is to provide a method for producing a zinc-containing thin film capable of producing a smooth thin film having good productivity and good quality.

As a result of diligent studies, the present inventors have found that a thin film forming raw material for the ALD method containing a zinc compound having a specific structure can solve the above-mentioned problems, and have completed the present invention. ..
That is, the present invention provides a thin film forming raw material for the ALD method containing a zinc compound represented by the following general formula (1).

In the formula, R ¹ and R ² each independently represent an alkyl group having 1 to 5 carbon atoms, a trimethylsilyl group or a trifluoromethyl group. However, R ¹ and R ² represent different groups.

Further, in the thin film forming raw material of the present invention, in the above general formula (1), ^{it is preferable that R 1} is a tertiary alkyl group and R ² is a secondary alkyl group.

Further, in the thin film forming raw material of the present invention, it is more preferable that ^{R 1} is a tert-butyl group and R ^{2 is an isopropyl group in the above general formula (1).}

In the present invention, a raw material gas obtained by vaporizing a thin film forming raw material for the ALD method of the present invention is introduced into a treatment atmosphere, and a zinc compound in the raw material gas is deposited on the surface of the substrate to form a precursor layer. The present invention provides a method for producing a zinc-containing thin film by an ALD method, which comprises one step and a second step of introducing a reactive gas into a treatment atmosphere and reacting the precursor layer with the reactive gas.

Further, in the production method of the present invention, it is preferable that the reactive gas is an oxidizing gas and the zinc-containing thin film is a zinc oxide thin film.

Further, in the production method of the present invention, it is preferable that the reactive gas is a gas containing ozone or water vapor.

Further, in the production method of the present invention, it is more preferable that the temperature at which the precursor layer reacts with the reactive gas is in the range of 50 ° C. to 200 ° C.

Further, it is preferable to include a step of exhausting the gas in the processing atmosphere between the first step and the second step and at least one after the second step.

According to the present invention, by containing a specific zinc compound, it is possible to provide a thin film forming raw material for the ALD method, which has a low melting point, is highly volatile, and can react with a reactive gas at a low temperature. .. Further, by using the thin film forming raw material of the present invention, it is possible to provide a method for producing a smooth zinc-containing thin film having high productivity and good quality by the ALD method.

It is the schematic which shows an example of the ALD apparatus used in the manufacturing method of the zinc-containing thin film which concerns on this invention. It is the schematic which shows another example of the ALD apparatus used in the manufacturing method of the zinc-containing thin film which concerns on this invention. It is the schematic which shows still another example of the ALD apparatus used in the manufacturing method of the zinc-containing thin film which concerns on this invention. It is the schematic which shows still another example of the ALD apparatus used in the manufacturing method of the zinc-containing thin film which concerns on this invention.

<Thin film forming raw material>
First, a thin film forming raw material for the ALD method of the present invention will be described.
The thin film forming raw material of the present invention is characterized by containing a zinc compound represented by the above general formula (1), and this zinc compound is a precursor for forming a thin film by the ALD method. It is used as.

In the above general formula (1), R ¹ and R ² each independently represent an alkyl group having 1 to 5 carbon atoms, a trimethylsilyl group or a trifluoromethyl group. However, R ¹ and R ² are different groups.

Since the zinc compound is used as a precursor when forming a thin film by the ALD method, it is a liquid at an ordinary pressure of 25 ° C., and the temperature when reduced by 50% by mass by a reduced pressure thermogravimetric differential thermal analyzer (TG-DTA) is 100. It is preferably ℃ or less.

Here, in the above general formula (1) ^{, examples of the alkyl group having 1 to 5 carbon atoms represented by R 1} and R ² include a methyl group, an ethyl group, a propyl group, an isopropyl group, and an n-butyl group. , Isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, sec-pentyl group, tert-pentyl group and the like.

In the present invention, ^{a zinc compound in which R 1} is a tertiary alkyl group and R ² is a secondary alkyl group has a low melting point, is highly volatile, reacts with a reactive gas at a low temperature, and is a zinc-containing thin film with good productivity. Is preferable, ^{and a zinc compound in which R 1} is a tert-butyl group and R ² is an isopropyl group is more preferable because its effect is more remarkable.

Specific examples of the zinc compound represented by the general formula (1) include the following No. 1 to No. 20 is mentioned, but the present invention is not limited to these compounds. The following compound No. 1 to No. In 20, "Me" represents a "methyl group", "Et" represents an "ethyl group", "iPr" represents an "isopropyl group", and "tBu" represents a "tert-butyl group". , "SBu" represents "sec-butyl group", "iBu" represents "isobutyl group", "tAm" represents "tert-pentyl group", and "SiMe ₃ " represents "SiMe 3". It represents a "trimethylsilyl group" and "CF ₃ " represents a "trifluoromethyl group".

The method for producing the compound represented by the general formula (1) is not particularly limited, and the compound is produced by applying a well-known reaction. As a production method, for example, when R ¹ is a tertiary alkyl group and R ² is a secondary alkyl group, a dialkylamine having these alkyl groups is dissolved in tetrahydrofuran (THF) to dissolve n-butyllithium (n-butyllithium). After reacting with nBuLi) to prepare a THF solution of the lithium dialkylamide compound, this solution is added dropwise to an ethyl ether solution of zinc chloride to react the lithium dialkylamide compound with zinc chloride to remove the solvent. It can be obtained by adding hexane to the obtained residue, filtering, distilling off the solvent from the filtrate, and then distilling and purifying.

The thin film forming raw material for the ALD method of the present invention may contain a zinc compound represented by the above general formula (1) and be used as a thin film precursor, and the composition thereof is the type of the target thin film. Depends on. For example, when producing a thin film containing only zinc as a metal, the thin film forming raw material of the present invention does not contain a metal compound other than zinc or a semimetal compound. On the other hand, when producing a thin film containing a zinc metal and a metal other than zinc and / or a semimetal, the thin film forming raw material of the present invention is a desired metal in addition to the zinc compound represented by the general formula (1). And / or a compound containing a semimetal (hereinafter referred to as "another precursor") can be contained.

Further, in the multi-component ALD method using a plurality of precursors, the other precursors that can be used with the zinc compound represented by the above general formula (1) are not particularly limited, and are thin films for the ALD method. A well-known general precursor used as a forming raw material can be used.

The other precursors described above include, for example, one or two types 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. The above and compounds with silicon or metal can be mentioned. The metal species of Precasa include lithium, sodium, potassium, magnesium, calcium, strontium, barium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, iron, osmium, ruthenium, and cobalt. , Rodium, iridium, nickel, palladium, platinum, copper, silver, gold, zinc, aluminum, gallium, indium, germanium, lead, antimony, bismuth, radium, scandium, ruthenium, ittrium, lantern, cerium, praseodymium, neodymium, promethium , Samalium, Europium, Gadolinium, Terbium, Dysprosium, Holmium, Elbium, Thulium, Itterbium or Ruthenium.

Examples of the alcohol compound used as the organic ligand of the above-mentioned precursor include methanol, ethanol, propanol, isopropyl alcohol, butanol, sec-butyl alcohol, isobutyl alcohol, tert-butyl alcohol, pentyl alcohol and isopentyl alcohol. , Alcohols such as tert-pentyl alcohols; 2-methoxyethanol, 2-ethoxyethanol, 2-butoxyethanol, 2- (2-methoxyethoxy) ethanol, 2-methoxy-1-methylethanol, 2-methoxy-1 , 1-dimethylethanol, 2-ethoxy-1,1-dimethylethanol, 2-isopropoxy-1,1-dimethylethanol, 2-butoxy-1,1-dimethylethanol, 2- (2-methoxyethoxy) -1 , 1-Dimethylethanol, 2-propoxy-1,1-diethylethanol, 2-sec-butoxy-1,1-diethylethanol, 3-methoxy-1,1-dimethylpropanol and other ether alcohols; dimethylaminoethanol, Ethylmethylaminoethanol, diethylaminoethanol, dimethylamino-2-pentanol, ethylmethylamino-2-pentanol, dimethylamino-2-methyl-2-pentanol, ethylmethylamino-2-methyl-2-pentanol, Examples thereof include dialkylaminoalcohols such as diethylamino-2-methyl-2-pentanol.

Examples of the glycol compound used as the organic ligand of the above-mentioned precursor include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 2,4-hexanediol, and 2, 2-Diol-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-hexane Examples thereof include diol, 2,4-dimethyl-2,4-pentanediol and the like.

Examples of the β-diketone compound used as the organic ligand of the other precursors described above include acetylacetone, hexane-2,4-dione, 5-methylhexane-2,4-dione, and heptane-2,4-dione. , 2-Methylheptan-3,5-dione, 5-methylheptan-2,4-dione, 6-methylheptan-2,4-dione, 2,2-dimethylheptan-3,5-dione, 2,6 -Dimethylheptane-3,5-dione, 2,2,6-trimethylheptan-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-ethyldecane- Alkyl-substituted β-diketones such as 3,5-dione, 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, 1,3-diperfluorohexylpropane- Fluorine-substituted alkyl β-diketones such as 1,3-dione; 1,1,5,5-tetramethyl-1-methoxyhexane-2,4-dione, 2,2,6,6-tetramethyl-1- Examples thereof include ether-substituted β-diketones such as methoxyheptan-3,5-dione and 2,2,6,6-tetramethyl-1- (2-methoxyethoxy) heptane-3,5-dione.

Examples of the cyclopentadiene compound used as the organic ligand of the above-mentioned precursor include cyclopentadiene, methylcyclopentadiene, ethylcyclopentadiene, propylcyclopentadiene, isopropylcyclopentadiene, butylcyclopentadiene, and second butylcyclopentadiene. Examples thereof include isobutylcyclopentadiene, tert-butylcyclopentadiene, dimethylcyclopentadiene, tetramethylcyclopentadiene, pentamethylcyclopentadiene and the like, and examples of the organic amine compound used as the above-mentioned organic ligand include methylamine, ethylamine and propylamine. , Isopropylamine, butylamine, sec-butylamine, tert-butylamine, isobutylamine, dimethylamine, diethylamine, dipropylamine, diisopropylamine, ethylmethylamine, propylmethylamine, isopropylmethylamine and the like.

The other precursors described above are known in the art, and their manufacturing methods are also known. To give an example of the production method, for example, when an alcohol compound is used as the organic ligand, the above-mentioned inorganic salt of the metal or its hydrate is reacted with the alkali metal alkoxide of the alcohol compound. This makes it possible to manufacture a precursor. 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. Can be done.

In the multi-component ALD method as described above, a method of vaporizing and supplying the thin film-forming raw material independently for each component (hereinafter referred to as "single source method") and the multi-component raw material are mixed in advance with a desired composition. There is a method of vaporizing and supplying a mixed raw material (hereinafter referred to as "cocktail sauce method").
In the case of the single source method, as the other precursor, a compound having similar thermal and / or oxidative decomposition behavior to the zinc compound represented by the general formula (1) is preferable.
In the case of the cocktail sauce method, as the above-mentioned other precursor, in addition to having similar thermal and / or oxidative decomposition behavior to the zinc compound represented by the above general formula (1), a chemical reaction or the like at the time of mixing, etc. Those that do not cause deterioration due to

Further, in the case of the cocktail sauce method in the multi-component ALD method, a mixture of the zinc compound represented by the above general formula (1) and another precursor or a mixed solution obtained by dissolving the mixture in an organic solvent is used as a thin film forming raw material. can do.

As the above-mentioned organic solvent, a well-known general organic solvent can be used without any particular limitation. Examples of the organic solvent include acetate esters 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; methyl. Ketones such as butyl ketone, methylisobutylketone, ethylbutylketone, dipropylketone, diisobutylketone, methylamylketone, cyclohexanone, methylcyclohexaneone; hexane, cyclohexane, methylcyclohexane, dimethylcyclohexane, ethylcyclohexane, heptane, octane, toluene, Hydrocarbons such as xylene; 1-cyanopropane, 1-cyanobutane, 1-cyanohexane, cyanocyclohexane, cyanobenzene, 1,3-dicyanopropane, 1,4-dicyanobutane, 1,6-dicyanohexane, 1, Hydrocarbons having a cyano group such as 4-dicyanocyclohexane and 1,4-dicyanobenzene; pyridine, lutidine and the like can be mentioned. 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 operating temperature and the boiling point, the flash point, and the like.

When the thin film forming raw material for the ALD method of the present invention is a mixed solution with the above organic solvent, the total amount of precursor in the thin film forming raw material is 0.01 mol / liter to 2.0 mol / liter, particularly 0. It is preferable to prepare so as to be 05 mol / liter to 1.0 mol / liter.

Further, the thin film forming raw material for the ALD method of the present invention contains, if necessary, a nucleophile in order to improve the stability of the zinc compound represented by the above general formula (1) and other precursors. You may. Examples of the nucleophilic reagent include ethylene glycol ethers such as glyme, jigglime, triglime, and tetraglime, 18-crown-6, dicyclohexyl-18-crown-6, 24-crown-8, and dicyclohexyl-24-crown. Crown ethers such as -8, dibenzo-24-crown-8, ethylenediamine, N, N'-tetramethylethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, 1,1,4,7, Polyamines such as 7-pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetrahydrofuran, triethoxytriethyleneamine, cyclic polyamines such as cyclolam and cyclone, pyridine, pyrrolidine, piperidine, morpholin , N-Methylpyrrolidine, N-methylpiperidine, N-methylmorpholine, tetrahydrofuran, tetrahydropyran, 1,4-dioxane, oxazole, thiazole, oxathiolane and other heterocyclic compounds, methyl acetoacetate, ethyl acetoacetate, acetoacetate- Examples thereof include β-ketoesters such as 2-methoxyethyl or β-diketones such as acetylacetoaceto, 2,4-hexanedione, 2,4-heptandione, 3,5-heptandione and dipivaloylmethane. The amount of these nucleophiles used is preferably in the range of 0.1 mol to 10 mol, more preferably in the range of 1 mol to 4 mol, based on 1 mol of the total amount of precursor.

The total amount of the precursor is the zinc compound and zinc represented by the above general formula (1) when the thin film forming raw material for ALD of the present invention does not contain a metal compound other than the zinc compound and a semi-metal compound. It is the total amount of other precursors containing, and when the thin film forming raw material of the present invention contains other precursors, it is the total amount of the zinc compound represented by the above general formula (1) and other precursors.

It is desirable that the thin film forming raw material for ALD of the present invention contains as little as possible impurity metal elements other than the constituents thereof, impurity halogens such as impurity chlorine, and impurity organics. The impurity metal element content is preferably 100 ppb or less for each 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 it is used as a gate insulating film, a gate film, or a barrier layer of an LSI, it is necessary to reduce the contents of alkali metal elements and alkaline earth metal elements that affect the electrical characteristics of the obtained 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 amount of the impurity organic content is preferably 500 ppm or less, more preferably 50 ppm or less, still more preferably 10 ppm or less. In addition, since water causes particle generation in the thin film forming raw material and particle generation during thin film formation, precursors, organic solvents and nucleophiles are used to reduce the respective water content. It is better to remove as much water as possible in advance. The water content of each of the precursor, the organic solvent and the nucleophile is preferably 10 ppm or less, more preferably 1 ppm or less.

Further, it is preferable that the thin film forming raw material for the ALD method of the present invention contains as few particles as possible in order to reduce or prevent particle contamination of the formed thin film. Specifically, in the particle measurement by the light scattering type submerged particle detector in the liquid phase, the number of particles larger than 0.3 μm is preferably 100 or less in 1 ml of the liquid phase, and is larger than 0.2 μm. More preferably, the number of particles is 100 or less in 1 ml of the liquid phase.

<Manufacturing method of zinc-containing thin film>
Next, the method for producing the zinc-containing thin film of the present invention using the thin film forming raw material for the ALD method will be described.

A well-known ALD device can be used as the device used in the method for producing a zinc-containing thin film by the ALD method of the present invention. Specific examples of the device include a device capable of bubbling and supplying a precursor as shown in FIGS. 1 and 3, and a device having a vaporization chamber as shown in FIGS. 2 and 4. Further, as shown in FIGS. 3 and 4, an apparatus capable of performing plasma treatment on the reactive gas can be mentioned. It should be noted that the device is not limited to the single-wafer type device provided with the film forming chamber (hereinafter referred to as “deposition reaction part”) as shown in FIGS. 1 to 4, and a device capable of simultaneously processing a large number of sheets using a batch furnace should be used. You can also.

In the method for producing a zinc-containing thin film by the ALD method of the present invention, a raw material gas obtained by vaporizing the thin film-forming raw material is introduced into a deposition reaction section (treatment atmosphere), and the zinc compound in the raw material gas is deposited on the surface of the substrate. The step of forming the precursor layer (first step) and the step of introducing the reactive gas into the deposition reaction section (treatment atmosphere) and reacting the precursor layer with the reactive gas (second step). It is characterized by including.
Further, it is preferable to have a step (exhaust step) of exhausting the gas of the deposition reaction section (treatment atmosphere) between the first step and the second step and at least one after the second step.

As one embodiment of the method for producing a zinc-containing thin film in the present invention, the deposition by a series of operations in which the first step, the exhaust step, the second step and the exhaust step are sequentially performed as described above is set as one cycle, and this cycle is defined as A method for producing a zinc-containing thin film by repeating the process a plurality of times will be described.
Hereinafter, each step will be described in detail.

(First step)
In the first step, the raw material for forming the thin film for the ALD method described above is vaporized into steam (hereinafter referred to as “raw material gas”), and the raw material gas is introduced into the film forming chamber in which the substrate is installed. It includes a step and a precursor layer forming step of depositing a zinc compound in the raw material gas on the surface of a substrate installed in a deposition reaction part to form a precursor layer.

-Material gas introduction process As a method of transporting and supplying the thin film-forming raw material for the ALD method in the raw material gas introduction process, as shown in FIGS. 1 and 3, a container in which the thin film-forming raw material is stored (hereinafter, "raw material container"). It is vaporized by heating and / or depressurizing in (referred to as) to form a vapor, and if necessary, the vapor is introduced into the deposition reaction section where the substrate is installed together with a carrier gas such as argon, nitrogen, and helium. As shown in the method and FIGS. 2 and 4, the thin film-forming raw material is transported to the vaporization chamber in the form of a liquid or a solution, and vaporized by heating and / or depressurizing in the vaporization chamber to obtain a gas, and the vapor is used as a raw material. There is a liquid transport method in which gas is introduced into the deposition reaction section.
In the case of the gas transport method, the zinc compound itself represented by the above general formula (1) can be used as a thin film forming raw material.
In the case of the liquid transport method, the zinc compound represented by the above general formula (1) or a solution obtained by dissolving the compound in an organic solvent can be used as a thin film forming raw material. The mixture and the mixed solution may further contain a nucleophile and the like.

In addition to the above gas transport method and liquid transport method, as a method used in the raw material gas introduction step, a multi-component ALD method containing a plurality of precursors is used as a single source as described in the column of thin film forming raw materials. There are a method and a cocktail sauce method, and regardless of which introduction method is used, it is preferable that the thin film forming raw material for the ALD method of the present invention is vaporized at 0 ° C to 200 ° C. Further, when the thin film-forming raw material is vaporized into steam in the raw material container or in the vaporization chamber, the pressure in the raw material container and the pressure in the vaporization chamber are preferably in the range of 1 Pa to 10,000 Pa.

Here, examples of the material of the substrate installed in the deposition reaction section include silicon; ceramics such as silicon nitride, titanium nitride, tantalum nitride, titanium oxide, titanium nitride, ruthenium oxide, zirconium oxide, hafnium oxide, and lanthanum oxide. Glass; Metals such as metallic cobalt and metallic ruthenium can be mentioned. Examples of the shape of the substrate include plate-like, spherical, fibrous, and scaly shapes. The surface of the substrate may be flat or may have a three-dimensional structure such as a trench structure.

-Precursor layer forming step In the precursor layer forming step, the zinc compound represented by the above general formula (1) in the raw material gas introduced into the deposition reaction part where the substrate is installed is deposited on the surface of the substrate, and the surface of the substrate is formed. A precursor layer is formed in. At this time, the substrate may be heated, or the deposition reaction portion may be heated to apply heat. The conditions for forming the precursor layer are not particularly limited, and for example, the reaction temperature (base temperature), reaction pressure, deposition rate and the like are appropriately set according to the desired thickness of the precursor layer and the type of thin film forming raw material. You can decide. The reaction temperature is preferably 100 ° C. or higher, which is a temperature at which the thin film forming raw material for the ALD method of the present invention sufficiently reacts with the surface of the substrate, and more preferably 100 ° C. to 200 ° C. The reaction pressure is preferably 1 Pa to 1,000 Pa, more preferably 10 Pa to 1,000 Pa.

Further, the deposition rate can be controlled by the supply conditions (vaporization temperature, vaporization pressure), reaction temperature, and reaction pressure of the thin film forming raw material. If the deposition rate is high, the characteristics of the obtained thin film may deteriorate, and if it is low, problems may occur in productivity. Therefore, 0.01 nm / min to 100 nm / min is preferable, and 1 nm / min to 50 nm / min is preferable. More preferred.

When the thin film forming raw material contains a precursor other than the zinc compound represented by the general formula (1), the other precursor is also deposited on the surface of the substrate together with the zinc compound.

(Exhaust process)
After the first step, the raw material gas containing the zinc compound that has not been deposited on the surface of the substrate is exhausted from the deposition reaction section. At this time, it is ideal that the raw material gas is completely exhausted from the deposition reaction section, but it is not always necessary to completely exhaust the raw material gas. Examples of the exhaust method include a method of purging the inside of the system of the deposition reaction part with an inert gas such as helium, nitrogen, and argon, a method of exhausting by depressurizing the inside of the system, and a method of combining these. The degree of decompression in the case of depressurization is preferably in the range of 0.01 Pa to 300 Pa, more preferably in the range of 0.01 Pa to 100 Pa.

(Second step)
In the second step, after the exhaust step, the reactive gas is introduced into the deposition reaction part, and the reactive gas is transferred to the precursor layer, that is, the substrate by the action of the reactive gas or the action of the reactive gas and the action of heat. React with the zinc compound deposited on the surface.
Examples of the reactive gas include oxidizing gases such as oxygen, ozone, nitrogen dioxide, nitrogen monoxide, water vapor, hydrogen peroxide, formic acid, acetic acid and anhydrous acetic acid, reducing gases such as hydrogen, monoalkylamines and dialkyls. Examples thereof include organic amine compounds such as amines, trialkylamines and alkylenediamines, and nitrided gases such as hydrazine and ammonia. These reactive gases may be used alone or in combination of two or more. Among these, the thin film forming raw material for the ALD method of the present invention has a property of specifically reacting with an oxidizing gas at a low temperature, and particularly reacts with ozone and water vapor at a low temperature. It is preferable to use ozone or a gas containing water vapor as the reactive gas, and a gas containing water vapor is used because the film thickness obtained per cycle is thick and a thin film can be produced with high productivity. Is more preferable. When the reactive gas is an oxidizing gas, a zinc oxide-containing thin film is formed. Further, when the reactive gas is an oxidizing gas and only the zinc compound of the general formula (1) is used as the precursor in the first step, a zinc oxide thin film is formed.

The temperature when the action is performed using heat is preferably 50 ° C. to 200 ° C., more preferably 100 ° C. to 200 ° C. When the thin film forming raw material for the ALD method of the present invention and the reactive gas are used in combination, the ALD window is generally in the range of 100 ° C. to 150 ° C. It is more preferable to react the reactive gas. The pressure in the deposition reaction section when this step is performed is preferably 1 Pa to 10,000 Pa, more preferably 10 Pa to 1,000 Pa.

The thin film forming raw material for the ALD method of the present invention has good reactivity with the above-mentioned reactive gas, and by using the thin film forming raw material of the present invention, a high quality zinc-containing thin film having a low residual carbon content can be obtained. It can be manufactured with high productivity.

(Exhaust process)
After the second step, the unreacted reactive gas and by-product gas are exhausted from the deposition reaction section. At this time, it is ideal that the reactive gas and the by-product gas are completely exhausted from the deposition reaction portion, but it is not always necessary to completely exhaust the reactive gas and the by-product gas. The exhaust method and the degree of decompression in the case of depressurization are the same as those in the exhaust step performed between the first step and the second step described above.

As described above, the first step, the exhaust step, the second step, and the exhaust step are performed in order, and the deposition by a series of operations is regarded as one cycle, and this cycle is repeated a plurality of times until a thin film having a required film thickness is obtained. To produce a zinc-containing thin film having a desired film thickness. According to the method for producing a thin film by the ALD method, the film thickness of the zinc-containing thin film to be formed can be controlled by the number of cycles.

Further, in the method for producing a zinc-containing thin film of the present invention, as shown in FIGS. 3 and 4, energy such as plasma, light, and voltage may be applied to the deposition reaction portion, or a catalyst may be used. The time when the energy is applied and the time when the catalyst is used are not particularly limited, and for example, when the raw material gas of the thin film forming raw material for the ALD method in the first step is introduced, or when the precursor layer is formed by heating. Or, at the time of introducing the reactive gas in the second step, at the time of heating when reacting the reactive gas with the precursor layer, at the time of exhausting in the system in the exhaust step, or during each of the above steps.

Further, in the method for producing a thin film of the present invention, after forming the zinc-containing thin film, annealing treatment may be performed in an inert atmosphere, an oxidizing atmosphere or a reducing atmosphere in order to obtain better electrical characteristics. If it is necessary to embed a step, a reflow process may be provided. In this case, the temperature is preferably 200 ° C. to 1,000 ° C., more preferably 250 ° C. to 500 ° C.

The zinc-containing thin film produced by using the thin film forming raw material for the ALD method of the present invention includes metal, oxide ceramics, nitride ceramics, and glass by appropriately selecting other precursors, reactive gases, and production conditions. It can be a thin film of a desired type such as. The thin film is known to exhibit electrical characteristics, optical characteristics, and the like, and is applied to various usage modes. For example, these thin films are widely used in the production of electrode materials, resistance films, diamagnetic films used for recording layers of hard disks, catalyst materials for polymer electrolyte fuel cells, etc., for example, for memory elements represented by DRAM elements. Has been done.

Hereinafter, the present invention will be described in more detail with reference to Production Examples, Examples and the like. However, the present invention is not limited by the following examples and the like.

[Production Example 1] Compound No. Synthesis of 6
Put 5 g (43.43 mmol) of N-isopropyl-2-methylpropane-2-amine and THF (150 mL) in a 200 mL three-necked flask, cool to −78 ° C., and then nBuLi (1.57 M hexane solution). 27.7 mL (43.47 mmol) was added dropwise over 30 minutes. After slowly warming to room temperature, the mixture was stirred for 18 hours to prepare a THF solution of lithium-tert-butyl (isopropyl) amide. 43.4 g (20.7 mmol) of zinc chloride (6.5% ethyl ether solution) and 30 mL of THF were placed in a 500 mL four-necked flask, and the lithium-tert-butyl (isopropyl) amide prepared by the above step was placed therein. The THF solution was added dropwise over 1 hour under ice-cooling. After raising the temperature to room temperature and stirring for 18 hours, the solvent was removed under a bath temperature of 64 ° C. and reduced pressure. 100 mL of hexane was added to the obtained residue, and the mixture was stirred and then filtered. The solvent was removed under a bath temperature of 64 ° C. and reduced pressure, and the obtained yellow liquid was distilled under the conditions of a bath temperature of 79 ° C. and 51 Pa to obtain a colorless transparent liquid (yield 3.8 g, yield 63%). As a result of analysis results by 1H-NMR and elemental analysis by ICP emission spectroscopy, the obtained colorless transparent liquid was found to have the compound No. 1 of the target compound. It was confirmed that it was 6. The analysis results of the obtained colorless transparent liquid by ¹ H-NMR are shown below.

(1) ¹ H-NMR (heavy benzene) analysis results)
1.15ppm (12H, doublet), 1.18ppm (18H, singlet), 3.09ppm (2H, septet)

(2) Elemental analysis (theoretical value)
Zn: 22.3% (22.25%)

Compound No. obtained in Production Example 1 above. 6 and the following comparative compound No. 1 to No. The following evaluation was performed using 4. The following comparative compound No. 1 to No. In 4, "iPr" represents an "isopropyl group", "tBu" represents a "tert-butyl group", "sBu" represents a "sec-butyl group", and "iBu" represents "isobutyl". Represents "group".

(1) Evaluation of state and melting point The state of the compound at a normal pressure of 25 ° C. was visually observed, and the melting point of the solid compound was measured using a micromelting point measuring device. Each of these results is shown in Table 1.

(2) Temperature (° C.) when reduced by 50% by mass due to reduced pressure TG-DTA
Using TG-DTA, measurement was performed with 10 Torr, argon flow rate: 50 mL / min, heating rate of 10 ° C./min, and scanning temperature range of 30 ° C. to 600 ° C., and when the mass of the test compound was reduced by 50% by mass. The temperature (° C.) was evaluated as "the temperature (° C.) when the reduced pressure TG-DTA was reduced by 50% by mass". The lower the temperature (° C.) when the reduced pressure TG-DTA is reduced by 50% by mass, the lower the temperature at which steam can be obtained. Each of these results is shown in Table 1.

[Example 2] Production of zinc-containing thin film Compound No. A zinc-containing thin film was produced on a silicon wafer under the following conditions using the ALD apparatus of FIG. 1 using No. 6 as a thin film forming raw material. When the composition of the obtained thin film was confirmed by X-ray electron spectroscopy, the obtained thin film was a zinc oxide thin film, and no residual carbon was detected. Moreover, when the film thickness was measured by a scanning electron microscope, it was a smooth film having a film thickness of about 6 nm, and the film thickness obtained per cycle was about 0.04 nm.

(ALD device conditions)
Base: Silicon wafer Reaction temperature (base temperature): 100 ° C
Reactive gas: water vapor (process)
A series of steps consisting of the following (1) to (4) was regarded as one cycle, and 150 cycles were repeated.
(1) The vapor (raw material gas) of the thin film-forming raw material vaporized under the conditions of the raw material container temperature: 50 ° C. and the pressure inside the raw material container of 100 Pa is introduced into the deposition reaction section, and the system pressure is 100 Pa for 10 seconds on the surface of the silicon wafer. The zinc compound is deposited to form a precursor layer.
(2) The raw material gas containing the zinc compound that has not been deposited is exhausted from the system by argon purging for 15 seconds.
(3) A reactive gas is introduced into the deposition reaction section, and the precursor layer and the reactive gas are reacted at a system pressure of 100 Pa for 0.2 seconds.
(4) Unreacted reactive gas and by-product gas are exhausted from the system by argon purging for 60 seconds.

[Comparative Example 5]
Compound No. 6 is referred to as Comparative Compound No. A zinc-containing thin film was produced on a silicon wafer by the same method as in Example 2 except that it was changed to 1, but a smooth film could not be obtained. In addition, residual carbon was detected in the obtained film.

[Comparative Example 6]
Compound No. 6 is referred to as Comparative Compound No. A zinc-containing thin film was produced on a silicon wafer by the same method as in Example 2 except that it was changed to 2, but a smooth film could not be obtained. In addition, residual carbon was detected in the obtained film.

[Comparative Example 7]
Compound No. 6 is referred to as Comparative Compound No. A zinc-containing thin film was produced on a silicon wafer by the same method as in Example 2 except that it was changed to 3, but a smooth film could not be obtained. In addition, residual carbon was detected in the obtained film.

[Comparative Example 8]
Compound No. 6 is referred to as Comparative Compound No. A zinc-containing thin film was produced on a silicon wafer by the same method as in Example 2 except that it was changed to 4, but a smooth film could not be obtained. In addition, residual carbon was detected in the obtained film.

Based on the above, by using a specific zinc compound as a thin film forming raw material for the ALD method, a zinc-containing thin film that has a low melting point, is highly volatile, reacts with a reactive gas at a low temperature, and is a zinc oxide thin film with good productivity. It was confirmed that it was possible to manufacture.

Claims (8)

1. A thin film forming raw material for an atomic layer deposition method containing a zinc compound represented by the following general formula (1).
   

   

   (In the formula, R ¹ and R ² independently represent an alkyl group having 1 to 5 carbon atoms, a trimethylsilyl group or a trifluoromethyl group, respectively. However, R ¹ and R ² are different groups.)
2. The thin film forming raw material according to claim 1, wherein in the general formula (1), R ¹ is a tertiary alkyl group and R ^{2 is a secondary alkyl group.}
3. The thin film-forming raw material according to claim 1 or 2, wherein in the general formula (1), R ¹ is a tert-butyl group and R ^{2 is an isopropyl group.}
4. The raw material gas obtained by vaporizing the thin film-forming raw material according to any one of claims 1 to 3 is introduced into a treatment atmosphere, and the zinc compound in the raw material gas is deposited on the surface of the substrate to form a precursor layer. First step and
   A second step of introducing the reactive gas into the treatment atmosphere and reacting the precursor layer with the reactive gas is included.
   A method for producing a zinc-containing thin film by an atomic layer deposition method.
5. The method for producing a zinc-containing thin film according to claim 4, wherein the reactive gas is an oxidizing gas and the zinc-containing thin film is a zinc oxide thin film.
6. The method for producing a zinc-containing thin film according to claim 4 or 5, wherein the reactive gas is a gas containing ozone or water vapor.
7. The method for producing a zinc-containing thin film according to any one of claims 4 to 6, wherein the temperature at which the precursor layer reacts with the reactive gas is in the range of 50 ° C to 200 ° C.
8. The zinc-containing thin film according to any one of claims 4 to 7, further comprising a step of exhausting the gas in the treatment atmosphere between the first step and the second step and at least one after the second step. Manufacturing method.

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