JP4553642B2 - Organic iridium compound, process for producing the same, and process for producing film - Google Patents

Description

  The present invention relates to an organometallic compound that can be a material for producing an iridium-containing film on a substrate surface, a method for producing the same, and a method for producing an iridium-containing film.

In recent integrated circuits, ferroelectric memories using the remanent polarization of ferroelectrics have been actively studied. Specifically, lead zirconate titanate (PZT: Pb (Ti, Zr) O ₃ ), bismuth strontium tantalate (SBT: SrBi ₂ Ta ₂ O ₉ ), etc. have been studied, and these ferroelectric electrodes As a material, a noble metal thin film such as ruthenium, platinum, iridium, or an oxide thin film of these noble metals is required. In particular, iridium and iridium oxide are attracting attention as the center of future electrode materials. As a method for producing iridium and an iridium oxide thin film, a sputtering method or a chemical vapor deposition method (CVD method) is used. In particular, the CVD method makes it easy to produce a uniform film and is excellent in step coverage (step coverage). Therefore, in order to cope with higher density in recent circuits and electronic components, future thin film electrode production It is considered to become the mainstream of the process.

  As a raw material for forming a thin film using this CVD method, among metal compounds, an organometallic compound having a low melting point and easy handling is considered suitable. Conventionally, as an organometallic compound for depositing iridium or an iridium oxide thin film, tris (dipivaloylmethanato) iridium, tris (acetylacetonato) iridium, or (cyclopentadienyl) (1,5-cyclooctadiene) ) Iridium is being studied. Although these iridium compounds have high stability in the air and are not toxic, they are suitable as CVD raw materials, but they are solid at room temperature, which makes it difficult to vaporize the raw materials and transport them to the substrate. .

  Therefore, recently, research on iridium complexes having a low melting point has been actively conducted. As a technique for lowering the melting point of this iridium complex, there is a method in which at least one hydrogen atom of a cyclopentadienyl ring is substituted with an alkyl group in cyclopentadienyl (1,5-cyclooctadiene) iridium. .

  For example, as a cyclopentadienyl derivative, there is (1,5-cyclooctadiene) (ethylcyclopentadienyl) iridium (see, for example, Patent Document 1). This metal compound is liquid at room temperature, and its melting point is lower than that of (cyclopentadienyl) (1,5-cyclooctadiene) iridium, so that it has characteristics necessary as a raw material applied to the CVD method. It is supposed to be. However, since this compound has extremely high stability, the decomposition temperature of the complex is high, and it is inevitably necessary to increase the substrate temperature during film formation, resulting in poor step coverage (step coverage) during film formation. I had a problem that. Another problem is that it is difficult to form an iridium oxide film. In addition, as a report example of an iridium complex having ethylene and a cyclopentadienyl group as a ligand, there is a synthesis example of (cyclopentadienyl) bis (ethylene) iridium (for example, see Non-Patent Document 1). It is a solid compound and is not suitable as a CVD material.

Japanese Patent Laid-Open No. 11-292888

M.M. Dziallas, A.D. Hohn and H.H. Werner, J.M. Organomet. Chem. 330 (1987) 207-219

  The present invention has been made in view of the above technical problems. That is, regarding an organometallic compound that can be a raw material for forming an iridium-containing film, an organometallic compound having a low melting point, excellent vaporization characteristics, and a low film formation temperature on a substrate, its production method, and its organometallic compound were used. It aims at providing the manufacturing method of an iridium containing film | membrane.

  As a result of repeated studies to solve the above-mentioned problems, the present inventors have determined that a cyclopentadienyl ring (hereinafter referred to as Cp ring) of (cyclopentadienyl) bis (ethylene) iridium or a lower alkyl group on ethylene. As a result, a new iridium complex having a liquid melting point at room temperature and having good vaporization and decomposition properties has been developed.

That is, the present invention
General formula [1]

［式中Ｒ_１は水素原子または低級アルキル基を示す。また式中Ｒ_２は低級アルキル基を示す。］で表されることを特徴とする有機イリジウム化合物である。

[Wherein R ₁ represents a hydrogen atom or a lower alkyl group. In the formula, R ₂ represents a lower alkyl group. It is an organic iridium compound characterized by the above-mentioned.

  The present invention also provides a general formula [2].

［式中Ｒ_１は前述と同様を示す。また式中Ｘはハロゲン原子を示す。］または一般式［３］

[Wherein R ₁ represents the same as described above. In the formula, X represents a halogen atom. ] Or general formula [3]

［式中Ｒ_１及びＸは前述と同様を示す。］で表される化合物に、一般式［４］

[Wherein R ₁ and X are as defined above. In the compound represented by general formula [4]

［式中Ｒ_２は低級アルキル基を示す。また式中Ｍはアルカリ金属を示す。］で表される化合物を反応させることを特徴とする、一般式［１］で表される有機イリジウム化合物の製造方法である。

[Wherein R ₂ represents a lower alkyl group. In the formula, M represents an alkali metal. A compound represented by the general formula [1], wherein the compound represented by the general formula [1] is reacted.

  Furthermore, the present invention is a method for producing an iridium-containing film characterized by using an organic iridium compound represented by the general formula [1] as a raw material. Hereinafter, the present invention will be described in more detail.

  First, definitions of terms used in the present specification and specific examples thereof will be described.

In this specification, the lower alkyl group represents a linear, branched, or cyclic alkyl group having 1 to 6 carbon atoms. Accordingly, examples of the lower alkyl group used in R ₁ or R ₂ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, and pentyl. Group, isopentyl group, neopentyl group, tert-pentyl group, 1-methylbutyl group, 2-methylbutyl group, 1,2-dimethylpropyl group, hexyl group, isohexyl group, 1-methylpentyl group, 2-methylpentyl group, 3 -Methylpentyl group, 1,1-dimethylbutyl group, 2,2-dimethylbutyl group, 1,3-dimethylbutyl group, 2,3-dimethylbutyl group, 3,3-dimethylbutyl group, 1-ethylbutyl group, 2-ethylbutyl group, 1,1,2-trimethylpropyl group, 1,2,2-trimethylpropyl group, 1-ethyl 1-methylpropyl, 1-ethyl-2-methylpropyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cyclopropylmethyl, 1-cyclopropylethyl, 2-cyclopropylethyl, and cyclo Examples thereof include a butylmethyl group.

In the present invention, R ₁ represents a hydrogen atom or a lower alkyl group. R ₁ is preferably a methyl group or a hydrogen atom, and more preferably R ₁ is a hydrogen atom. On the other hand, in the present invention, R ₂ represents a lower alkyl group, preferably a methyl group, an ethyl group, a propyl group or a butyl group, and more preferably a methyl group or an ethyl group. In the present invention, X represents a halogen atom, and examples of the halogen atom include fluorine, chlorine, bromine, iodine atom, etc. Among them, chlorine or bromine atom is preferable. In the present invention, M represents an alkali metal, and examples of the alkali metal include lithium, sodium, potassium, etc. Among them, lithium or sodium is preferable.

  The organic iridium compound represented by the general formula [1] of the present invention is obtained by reacting the compound represented by the general formula [2] or [3] with the compound represented by the general formula [4]. be able to. The reaction conditions at this time are not particularly limited. For example, both may be added to an appropriate solvent and mixed and reacted at a low temperature. Although the post-treatment is not particularly limited, as a general method, the mixture after completion of the reaction is concentrated, and the target product is extracted from the resulting mixture with an organic solvent such as pentane, hexane, ether, etc., and an appropriate carrier is selected. The target organic iridium compound can be obtained by performing column chromatography using an appropriate organic solvent as an eluent and then performing distillation.

  An iridium-containing film can be produced using the organic iridium compound represented by the general formula [1] of the present invention as a raw material. The specific means of the manufacturing method is not particularly limited. For example, a CVD method may be used, an atomic layer deposition method (ALD method) may be used, or a spin coating method may be used. May be.

  Further, when an iridium-containing film is produced by the CVD method, the ALD method, or the like using the organic iridium compound represented by the general formula [1] of the present invention, the raw material supply method to the film formation chamber is not particularly limited. A gas bubbling method may be used, or a liquid injection method may be used.

  Furthermore, when producing an iridium containing film | membrane by CVD method or ALD method in this invention, the organic iridium compound used may be used as it is, and may be used as an organic iridium compound solution melt | dissolved in the organic solvent.

  Examples of organic solvents used as a solution include alcohols such as methanol, ethanol and isopropanol, esters such as ethyl acetate, butyl acetate and isoamyl acetate, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether and ethylene. Glycol ethers such as glycol monobutyl ether, ethers such as diethyl ether, glyme, diglyme, triglyme, tetrahydrofuran, methyl butyl ketone, methyl isobutyl ketone, ethyl butyl ketone, dipropyl ketone, diisobutyl ketone, methyl amyl ketone, cyclohexanone, etc. Examples include ketones, hydrocarbons such as hexane, cyclohexane, ethylcyclohexane, heptane, octane, benzene, toluene, and xylene. It is not limited to these.

  The organic iridium compound of the present invention can be quantitatively supplied because it is liquid under gas bubbling conditions when the CVD method is used as a method for producing an iridium-containing film. Further, since it can be thermally decomposed at a lower temperature than conventional materials, an iridium-containing film having excellent step coverage can be formed on the substrate. According to the present invention, an iridium-containing film excellent in mass productivity can be formed.

  EXAMPLES Next, although an Example demonstrates this invention in detail, this invention is not limited by these Examples.

Example 1 Synthesis and Thermal Decomposition Properties of (Ethylcyclopentadienyl) bis (ethylene) iridium 49 mg of diμ-chlorotetrakis (ethylene) diiridium (I) was added to 10 ml of THF, and the reaction flask was cooled to −78 ° C. Then, 10 ml of a THF solution containing 17 mg of lithium ethylcyclopentadienide was added. After stirring at −78 ° C. for 30 minutes, the temperature was gradually raised to room temperature, reacted for 1 hour, and concentrated to obtain a mud mixture. The mud mixture was extracted with hexane, and the extracted solution was subjected to column chromatography using alumina (eluent: hexane) to obtain 14 mg of the target product (ethylcyclopentadienyl) bis (ethylene) iridium. It was.

Pale yellow oil
¹ H-NMR (500 MHz, Benzene-d6, δ ppm)
4.78-4.77 (m, 2H), 4.66-4.65 (m, 2H), 2.60-2.58 (m, 4H), 1.90 (q, J = 2.5 Hz) , 2H), 0.94 (t, J = 2.5 Hz, 3H), 0.94-0.91 (m, 4H)
IR (neat, cm ⁻¹ )
3040, 2970, 2920, 2870, 1480, 1460, 1435, 1310, 1165, 1150, 1035, 1010, 990, 810, 790
MS (GC / MS, EI)
Molecular ion peak of (ethylcyclopentadienyl) bis (ethylene) iridium at ¹⁹³ Ir; m / z 342 (FIG. 1)
Moreover, the result of having measured the decomposition | disassembly characteristic of this compound is shown in FIG. As is clear from FIG. 2, the organic iridium compound of the present invention has a decomposition start temperature of about 220 ° C., and can be thermally decomposed at a lower temperature than the compound of Comparative Example 1 described below (conventional product).

The measurement conditions are as follows.
Measurement method: Input compensation differential scanning calorimetry (DSC)
Measurement conditions: Reference Alumina
Inert gas Nitrogen 50ml / min
Temperature increase 10 ° C./min.

Comparative Example 1 Decomposition characteristics of (ethylcyclopentadienyl) (1,5-cyclooctadiene) iridium In the same manner as in Example 1, (ethylcyclopentadienyl) (1,5-cyclooctadiene) iridium (conventional) Product) was measured. The results are shown in FIG. As is apparent from FIG. 3, this conventional product has a decomposition start temperature around 370 ° C.

Example 2 Synthesis of (methylcyclopentadienyl) bis (ethylene) iridium 0.97 g of di [mu] -chlorotetrakis (ethylene) diiridium (I) was added to 50 ml of THF, the reaction flask was cooled to -78 [deg.] C., and lithium 50 ml of a THF solution of 178 mg of methylcyclopentadienide was added. After stirring at -78 ° C for 1 hour and 40 minutes, the temperature was gradually raised to room temperature, reacted for 1 hour, and concentrated to obtain a mud mixture. The muddy mixture was extracted with hexane, and the extracted solution was subjected to column chromatography using alumina (eluent: hexane) to obtain 409 mg of the target product (methylcyclopentadienyl) bis (ethylene) iridium. It was.

Milky white solid
¹ H-NMR (500 MHz, Benzene-d6, δ ppm)
4.84 (t, J = 2.0 Hz, 2H), 4.59 (t, J = 2.0 Hz, 2H), 2.55-2.44 (m, 4H), 1.51 (s, 3H) ), 0.95-0.93 (m, 4H)
MS (GC / MS, EI)
Molecular ion peak of (methylcyclopentadienyl) bis (ethylene) iridium at ¹⁹³ Ir; m / z 328 (FIG. 4).

Example 3 Production of Iridium Film Using (Ethylcyclopentadienyl) bis (ethylene) iridium Using the apparatus shown in FIG. 5, a Si substrate having a SiO ₂ curtain of 100 nm formed on the surface was used as the substrate 4. About 10 g of (ethylcyclopentadienyl) bis (ethylene) iridium was placed in the raw material container 1 and heated in an oil bath to a constant temperature of 50 ° C. Using the vacuum pump 11 and the pressure adjusting valve, the reaction vessel 3 was adjusted to 10 Torr, and the inside of the raw material container 1 was adjusted to 100 Torr. Nitrogen was used as the carrier gas 7 and the flow rate was set to 100 sccm with the mass flow controller 10. Oxygen was used as the oxidizing gas 5 and nitrogen was used as the counter gas 6. The oxidizing gas flow rate was set to 10 sccm with the mass flow controller 8, and the counter gas flow rate was set to 90 sccm with the mass flow controller 9. The substrate 4 was set to 400 ° C., and film formation was performed for 60 minutes while being heated and held. The film formed was a metal iridium film and the film thickness was 300 nm.

1 is a chart showing a GC / MS chart of an iridium compound obtained in Example 1. FIG. FIG. 3 is a diagram showing the decomposition characteristics of the iridium compound obtained in Example 1. FIG. 3 is a graph showing the decomposition characteristics of (1,5-cyclooctadiene) (ethylcyclopentadienyl) iridium obtained in Comparative Example 1. 4 is a diagram showing a GC / MS chart of (methylcyclopentadienyl) bis (ethylene) iridium obtained in Example 2. FIG. 6 is a schematic view of a CVD method apparatus used in Example 3. FIG.

Explanation of symbols

1. 1. Raw material container Oil bath 3. Reaction tank 4. Substrate 5. Oxidizing gas6. Counter gas 7. Carrier gas8. Mass flow controller9. Mass flow controller 10. Mass flow controller 11. Vacuum pump 12. exhaust

Claims (6)

General formula [1]

[Wherein R ₁ represents a hydrogen atom or a lower alkyl group. In the formula, R ₂ represents an ethyl group, a propyl group or a butyl group . ] The organic iridium compound characterized by the above-mentioned. The organic iridium compound according to claim 1, wherein R ₁ represents a hydrogen atom. General formula [2]

[Wherein R ₁ represents a hydrogen atom or a lower alkyl group. In the formula, X represents a halogen atom. ] Or general formula [3]

[Wherein R ₁ and X are as defined above. In the compound represented by general formula [4]

[Wherein R ₂ represents an ethyl group, a propyl group or a butyl group . In the formula, M represents an alkali metal. A method for producing an organic iridium compound according to claim 1 or 2, wherein the compound represented by formula (I) is reacted. The production method according to claim 3, wherein R ₁ represents a hydrogen atom. A method for producing an iridium-containing film, characterized in that the organic iridium compound according to claim 1 or 2 is used as a raw material. 6. The method for producing an iridium-containing film according to claim 5, wherein R ₁ represents a hydrogen atom.

Images