JP2003321415A - Tris(octane-2,4-dionato)iridium, raw material for chemical vapor growth comprising the same and method for producing thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid iridium compound suitable to the CVD method, to provide a raw material for CVD comprising the same, and to provide a method for producing iridium thin films using said raw material. <P>SOLUTION: The liquid iridium compound is tris(octane-2,4-dionato)iridium. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel compound, tris (octane-2,4-dionate) iridium, and a chemical vapor deposition (hereinafter sometimes referred to as CVD) raw material containing the same. And a method for manufacturing an iridium thin film using the CVD raw material.

[0002]

2. Description of the Related Art Iridium conductive film is expected to be applied as an electrode material for semiconductors such as capacitor electrodes of memory devices such as DRAM and FeRAM using thin film capacitors using high-ferroelectric material. Has been done.

Further, as a method for producing a metal thin film, a sputtering method, an ion plating method, a coating pyrolysis method and the like can be mentioned. Regarding the above iridium electrode for a memory device capacitor, composition controllability and step coverage are provided. The CVD method is being considered as the optimum thin film manufacturing process because of its superiority and compatibility with the capacitor film manufacturing process.

However, CVD of the iridium conductive film is performed.
As the iridium compound to be produced by the method, those proposed so far have not necessarily had sufficient properties. As the iridium compound used in the CVD method, Japanese Unexamined Patent Publication (Kokai) No. 8-85873 discloses a highly sublimable solid iridium compound using β-diketone having a perfluoroalkyl group as a ligand. The thin film obtained by using has a problem that fluorine atoms that adversely affect the physical properties of the thin film remain in the film.

Further, JP-A-8-85873 and JP-A-9-85387
-49081 and JP-A-8-260148 report iridium complexes of various β-diketones containing no fluorine atom. However, since these compounds are solids having a high melting point, it is necessary to gasify them by a sublimation phenomenon in the vaporization step of the raw material or to keep the raw material at a temperature higher than the melting point. There was a problem with the raw material transportation inline.

Therefore, an object of the present invention is to provide a liquid iridium compound suitable for the CVD method, a CVD raw material using the same,
Another object of the present invention is to provide a method for producing an iridium thin film using the CVD raw material.

[0007]

As a result of repeated studies, the present inventor found a liquid tris (β-diketonato) iridium obtained by using octane-2,4-dione as a ligand, and found that the compound Have found that the above problems can be solved.

The present invention has been made on the basis of the above findings, and is based on tris (octane-2,4-dionat) iridium, a CVD raw material containing the same, and a CVD method using the CVD raw material. A method for manufacturing an iridium thin film is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described in detail below.

Tris (octane-2,4-dionato) iridium, which is a novel compound of the present invention, is represented by the following chemical structural formula.

[0011]

[Chemical 1]

In the above chemical structural formula, the bonding modes of the six-membered ring structure formed by the oxygen-metal bond are described in a distinct form. This is because the metal atom and the ligand β-diketone are Is one of the methods of expressing the complex compound, and does not strictly distinguish the bonding mode of the 6-membered ring structure. Further, tris (octane-2,4-dionat) iridium of the present invention has the following four types of isomers in the three-dimensional structure, but they are not distinguished by these isomers and one of these Alternatively, it is a mixture of two or more kinds.

[0013]

[Chemical 2]

Octane-2, which is a ligand according to the present invention,
4-dione is a known β-diketone, and a metal complex compound using this is described in, for example, JP-A-4-503087.
In the gazette, calcium, strontium, barium,
Copper, yttrium and thallium have been reported.
Octane-2,4-dione can be obtained, for example, by a known condensation reaction between acetone and a reactive derivative such as a pentanoic acid ester or a pentanoic acid halide.

The method for producing tris (octane-2,4-dionato) iridium of the present invention is not particularly limited, and well-known general β-diketone and H ₂ IrC are used.
l ₆ , (NH ₄ ) ₂ IrCl ₆ , (NH ₄ ) ₃ IrCl ₆ , I
It can be carried out in the same manner as the reaction with an iridium salt compound such as rCl ₃ .

For example, a method of adding alcohol to an aqueous solution of H ₂ IrCl ₆ hydrate to reduce it, and reacting this with octane-2,4-dione in the presence of a base, (NH ₄ ) ₂ IrC.
l ₆ aqueous alcohol added was reduced to hydrate, which method is reacted with the presence octane-2,4-dione base, IrCl ₃ solution and octane-2 was made basic,
Examples thereof include a method of reacting 4-dione.

Since the tris (octane-2,4-dionato) iridium of the present invention is a liquid at room temperature, it is stable in supply when used as a raw material for CVD, as compared with a well-known β-diketone complex which is a solid. It has the advantage of excellent operability. The melting points of known β-diketone complexes are shown below.

Tris (acetylacetonato) iridium; 269 ° C., tris (2,2,6,6-tetramethylheptane-3,5-dionato) iridium; 235-2
38 ° C, tris (2,2,6-trimethylheptane-
3,5-Dionato) iridium; 148 to 150 ° C., tris (2,6-dimethylheptane-3,5-dionato)
Iridium; 141-143 ° C.

The chemical vapor deposition (CVD) raw material of the present invention contains the above-mentioned tris (octane-2,4-dionato) iridium, and its form depends on the CVD method used. It is appropriately selected according to a method such as a transportation and supply method.

As the above-mentioned transportation and supply method, the CVD raw material is vaporized by heating and / or depressurizing it in the raw material container, and it is sent to the deposition reaction section together with a carrier gas such as argon, nitrogen or helium which is used as necessary. There are a gas transportation method for introducing and a liquid transportation method for transporting a CVD raw material in a liquid or solution state to a vaporization chamber, vaporizing it by heating and / or depressurizing in the vaporization chamber, and introducing it to a deposition reaction section. In the case of the gas transport method, the tris (octane-) of the present invention is used.
2,4-Dionato) iridium itself is the raw material for CVD, and in the case of the liquid transport method, tris (octane-2,
4-Dionato) iridium itself or a solution obtained by dissolving the compound in an organic solvent serves as a raw material for CVD.

The organic solvent used for the above CVD raw material is not particularly limited, and a well-known general organic solvent can be used. Examples of the organic solvent include methanol, ethanol, 2-propanol, n-
Alcohols such as butanol; acetic acid esters such as ethyl acetate, butyl acetate, methoxyethyl acetate; ether alcohols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether; tetrahydrofuran, ethylene glycol Ethers such as dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, dibutyl ether; methyl butyl ketone, methyl isobutyl ketone, ethyl butyl ketone,
Ketones such as dipropyl ketone, diisobutyl ketone, methyl amyl ketone, cyclohexanone and methylcyclohexanone; hydrocarbons such as hexane, cyclohexane, methylcyclohexane, ethylcyclohexane, heptane, octane, toluene and xylene; 1-cyanopropane, 1- Cyanobutane, 1-cyanohexane, cyanocyclohexane, cyanobenzene, 1,3-dicyanopropane, 1,4-dicyanobutane, 1,6-dicyanohexane, 1,4-dicyanocyclohexane, 1,4-
Hydrocarbons having a cyano group such as dicyanobenzene; pyridine and lutidine may be mentioned, and these are appropriately selected depending on the solubility of the solute, the relationship between the use temperature and the boiling point, the flash point and the like. When the above organic solvent is used, the CVD of the present invention
The concentration of tris (octane-2,4-dionat) iridium in the raw material is generally 5 to 70% by mass.

Further, the raw material for CVD of the present invention may contain a nucleophilic reagent in order to impart the stability of tris (octane-2,4-dionato) iridium, if necessary. Examples of the nucleophilic reagent include ethylene glycol ethers such as glyme, diglyme, triglyme and tetraglyme, 18-crown-6, dicyclohexyl-1.
Crown ethers such as 8-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
Polyamines such as 7,10,10-hexamethyltriethylenetetramine, cyclic polyamines such as cyclam and cyclen, β-ketoesters such as methyl acetoacetate, ethyl acetoacetate, and 2-methoxyethyl acetoacetate, or β-diketones The amount of these nucleophiles used as stabilizers is tris (octane-2,4-
Dionato) iridium is preferably 0.
It is used in the range of 1 mol to 10 mol, particularly preferably 1 mol.
Used at ~ 4 moles.

The method for producing a thin film of the present invention is the above-mentioned CV
This is based on a chemical vapor deposition (CVD) method using a raw material for D. The CVD method is a method of introducing a vaporized raw material and a reactive gas used as needed onto a substrate, and then decomposing and / or reacting the raw material on the substrate to grow and deposit a thin film on the substrate. Refers to. In the method for producing a thin film of the present invention, the raw material transportation and supply method, the deposition method, the production conditions, the production apparatus and the like are not particularly limited, and well-known general conditions and methods can be used.

The reactive gas used according to the above need includes, for example, hydrogen as a reducing gas.

As the above-mentioned transportation and supply method, the above-mentioned gas transportation method, liquid transportation method and the like can be mentioned.

As the above-mentioned deposition method, thermal CVD for depositing a thin film by reacting the raw material gas or the raw material gas and the reactive gas only with heat, plasma CVD using heat and plasma, light using heat and light Optical plasma CVD using CVD, heat, light, and plasma. AL that divides the deposition reaction of CVD into elementary processes and performs stepwise deposition at the molecular level.
(Atomic layer) -CVD.

As the above-mentioned manufacturing conditions, there may be mentioned a reaction temperature (substrate temperature), a reaction pressure, a deposition rate and the like. The reaction temperature is preferably 200 ° C or higher, which is a temperature at which tris (octane-2,4-dionate) iridium sufficiently reacts, and more preferably 400 to 800 ° C. The reaction pressure is 10 to 5 in the case of thermal CVD or photo CVD.
000 Pa is preferable, and 1 when plasma is used
0 to 2000 Pa is preferable. Further, the deposition rate can be controlled by the supply conditions (vaporization temperature, vaporization pressure) of the raw material, reaction temperature and reaction pressure. The deposition rate is
If it is large, the properties of the obtained thin film may deteriorate, and if it is small, it may cause a problem in productivity.
00 nm / min is preferable, and 5-1000 nm / min is more preferable.

Further, in the method of manufacturing a thin film of the present invention, after the thin film is deposited, an annealing treatment may be carried out in order to obtain better electric characteristics, and a reflow step is provided when step filling is required. May be. In this case, the temperature is 600 to 1200 ° C, preferably 700 to 1000 ° C.

[0029]

EXAMPLES The present invention will be described in more detail with reference to production examples and examples. However, the present invention is not limited to the following examples.

[Production Example] H ₂ IrCl ₆ .6H ₂ O
700 ml of ethanol was added to a solution of 53 g (0.103 mol) dissolved in 2500 ml of water, and the mixture was stirred at 70 ° C. for 3 hours. While cooling with ice, 200 g of 10 mass% sodium hydroxide aqueous solution was added, and then the system was returned to neutral with 10 mass% acetic acid aqueous solution, and octane-2,4-dione was added to 41%.
0 g (0.8 mol) was added, and the mixture was heated with stirring at 60 ° C for 1 hour. After extracting the reaction product from the reaction system with 4000 g of diethyl ether, the solvent was removed to obtain a dark red liquid product. The liquid substance was separated by column chromatography using silica gel, hexane and ethyl acetate. 4. The solvent was removed from the obtained separated liquid, and the target product, tris (octane-2,4-dionate) iridium; dark red transparent liquid 5.
1 g (yield 8%) was obtained. About the obtained liquid, ¹ H
-The structure was confirmed by NMR (deuterated chloroform solvent), IR and elemental analysis (carbon, hydrogen; CHN analyzer, metal; ICP analysis). The analysis results are shown below.

(Analysis Results) ¹ H-NMR (Deuterated Benzene Solvent) From the results below, it was confirmed that the obtained liquid was a mixture of at least three structural isomers. (0.82-0.96; m + m; 6H) (1.20-
1.4; m; 2H) (1.45-1.67; m; 2H)
(1.95-2.02; s + s + s; 3H) (2.15
-2.40; m + m; 2H) (5.39-5.5; s +
s + s; 1H) .IR (cm ⁻¹ ) It was confirmed that there was no peak at 1600 cm ⁻¹ characteristic of β-diketone, and the absorption wave number characteristic of β-diketone complex shown below was confirmed. 2956, 2931, 1556, 1519, 1402,
1268, 1186, 1093, 1022, 777, 6
55 Elemental analysis (unit: mass%) Carbon 46.7 (calculated value 46.81), hydrogen 6.33 (calculated value 6.384), iridium 31.1 (calculated value 31.55).
21)

[Example] With the CVD apparatus shown in FIG.
Using tris (octane-2,4-dionate) iridium obtained in the above-mentioned Production Example, an iridium thin film was produced on a silicon wafer under the following reaction conditions. After forming the film, annealing was performed in hydrogen at 500 ° C. for 10 minutes. With respect to the manufactured iridium thin film, the film thickness was measured with a stylus profilometer, and the specific resistance was measured with a four-probe resistance meter. The reaction conditions and measurement results are shown below.

(Reaction conditions) Vaporization chamber temperature: 150 ° C., raw material flow rate: 20 mg / min, argon flow rate: 300 sccm, hydrogen gas flow rate: 100 sc
cm, reaction pressure: 600 Pa, reaction time: 5 minutes, substrate temperature: 500 ° C. (measurement result) film thickness: 100 nm, specific resistance value: 41 μΩcm

As is clear from the above-mentioned examples, the CVD raw material of the present invention using the liquid tris (octane-2,4-dionate) iridium is different from the conventional CVD raw material using the iridium compound. In addition, it does not contain a fluorine atom, and there is no problem of feedability of raw material gas or transportation of raw material in-line.

[0035]

INDUSTRIAL APPLICABILITY The present invention provides a liquid iridium compound suitable for a CVD method, a CVD raw material using the same, and the CVD.
It is possible to provide a method for producing an iridium thin film using a raw material for use.

[Brief description of drawings]

FIG. 1 is a CV used for manufacturing the thin film of the present invention.
It is a schematic diagram showing an example of D device.

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Claims (3)

[Claims] 1. Tris (octane-2,4-dionat)
iridium. 2. A chemical vapor deposition raw material comprising the compound according to claim 1. 3. A method for producing an iridium thin film by the chemical vapor deposition method using the raw material for chemical vapor deposition according to claim 2.