JP3180616B2 - Organic iridium compounds - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic iridium compound for forming an iridium thin film or an iridium oxide thin film, and more particularly to an iridium thin film or an iridium oxide thin film useful as a wiring material for a semiconductor device. Metalorganic Chemical Vapor Deposition:
Hereinafter, it is referred to as “MOCVD method”. The present invention relates to an organic iridium compound that is suitable for use as a vapor deposition material when formed according to (1).

[0002]

2. Description of the Related Art Conventionally, iridium vapor deposition raw materials used for forming various iridium thin films such as wiring materials for semiconductor devices by MOCVD are represented by the following structural formula (I).
(Methylcyclopentadienyl) (1, 1)
An organic iridium compound comprising (5-cyclooctadiene) iridium (I) is known.

[0003]

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In order to form an iridium thin film by the MOCVD method using such a deposition material, for example, as shown in a schematic explanatory view of FIG.
The substrate 6 is placed on the upper surface. On the other hand, in the heating furnace 3 provided in connection with the reaction furnace 8, the vapor deposition raw material 1 made of the organic iridium compound in the vaporization vessel 2 is vaporized. The carrier gas is introduced into the reaction furnace 8 and diffused by a carrier gas such as Ar or N ₂ introduced from the reactor, and a reducing gas such as hydrogen gas is introduced into the reaction furnace 8 from the pipe 5 as a reaction gas. Then, iridium is deposited on the heating substrate 6. In the figure, 9 is a vacuum pipe, P is a pressure gauge, M ₁ and M ₂
Is a flow controller. This method is called a thermal decomposition type MOCVD method.

[0005]

However, the organic iridium compound represented by the structural formula (II), which is conventionally used as a vapor deposition material in the above-mentioned thermal decomposition type MOCVD method, has a melting point of 38.5 to 40 ° C. In addition, heating is necessary in order to supply a raw material using a liquid mass flow controller because it is solid at room temperature. Figure 1 shows the deposition material that is solid at room temperature.
In the case of vaporization in the vaporization container 2 shown in (1), it is difficult to accurately control the vaporization rate, and the deposition rate of the iridium or iridium oxide thin film formed on the substrate surface becomes uneven. Further, the above-mentioned conventional organic iridium compound also has a problem in thermal stability, such as causing a thermal decomposition reaction in the vaporization container 2 in addition to vaporization during heating in vaporization.

[0006] In recent years, iridium or iridium oxide thin films applied thereto have been increasingly thinned due to high integration of semiconductor devices. However, as described above, conventional organic iridium compounds have been used in such thin films. Since it is difficult to control the corresponding uniform and dense film thickness, improvement thereof is desired.

[0007] The present invention solves the above-mentioned conventional problems, and when forming an iridium thin film and an iridium oxide thin film by a MOCVD method such as a thermal decomposition type MOCVD method, the vaporization rate is uniform and the thermal stability during vaporization is improved. An object of the present invention is to provide an organic iridium compound for forming a high-purity iridium thin film and an iridium oxide thin film which is excellent and is liquid at room temperature.

[0008]

The organic iridium compound of the present invention is represented by the following structural formula (I): (methylcyclopentadienyl) (1,5-dimethyl-1,5-cyclooctadiene) iridium. (I).

[0009]

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That is, from the above-mentioned viewpoints, the present inventors have found that when producing iridium thin films and iridium oxide thin films by other MOCVD methods including the pyrolysis type MOCVD method, the vaporization rate is uniform and the Of organic diiridium represented by the above structural formula (I) as a result of studying to find a high-purity iridium thin film and an iridium oxide thin film deposition material which is excellent in thermal stability and liquid at room temperature. The compound is a liquid at room temperature, and when this organic iridium compound is used as a deposition material, a stable vaporization rate can be obtained as compared with the conventional organic iridium compound represented by the structural formula (II). With the knowledge that it exhibits excellent volatility and thermal stability,
The present invention has been completed.

The organic iridium compound according to the present invention is, for example, as shown in Examples described later, 1,5-dimethyl-1,5-cyclooctadiene iridium chloride dimer and sodium methylcyclopentadiene. It can be synthesized by reacting with an enide.

Such an organic iridium compound of the present invention can be used as a vapor deposition material by MOCVD such as thermal decomposition type MOCVD by the same operation as a conventional organic iridium compound. In the film formation by the MOCVD method, as described above, when a reducing gas such as hydrogen is used as the reaction gas to be supplied at the same time as the source gas, an iridium thin film is used, and an oxidizing gas such as oxygen is used. If you have
An iridium oxide thin film can be formed.

[0013]

The organic iridium compound represented by the structural formula (I) is a liquid at around room temperature. In this organic iridium compound, the 1,5-dimethyl-1,5-cyclooctadiene ligand used as one of the ligands has a methyl group having a large steric hindrance on the cyclooctadiene ring, Thereby, since the decomposition reaction to iridium metal is suppressed, it is possible to obtain a more stable vaporization rate than the conventional organic iridium compound, and it shows excellent volatility and thermal stability.

[0014]

The present invention will be described more specifically with reference to the following examples.

Example 1 [Synthesis of organic iridium compound] [(1,5-dimethyl-1,5-cyclooctadiene)]
[Ir (μ-Cl)] ₂ 500 g (13.74 mmol) of dry tetrahydrofuran sufficiently degassed with nitrogen was poured into the mixture and cooled to -78 ° C. While cooling the reaction system to -78 ° C, 3.1 g of sodium methylcyclopentadienide (30.36 mm
ol) was dropped from the dropping funnel drop by drop with vigorous stirring. The reaction system was returned to room temperature, stirred for 30 minutes, filtered under an argon stream, and the filtrate was distilled off under reduced pressure at 35 ° C. to obtain a yellow liquid. Purification is
After extraction with pentane, distillation was performed under reduced pressure to obtain a light yellow liquid of the present organic iridium compound represented by the structural formula (I): (methylcyclopentadienyl) (1,5-
6.2 g of dimethyl-1,5-cyclooctadiene) iridium (I) was obtained.

The identification of the obtained organic iridium compound is as follows.
The analysis was performed by NMR, mass spectrum analysis and elemental analysis.

1H-NMR (CDCl ₃ ): δH =
5.01 (t, 2H, CH), 5.20 (br, 2H, CH)
CH), 1.82 (s, 3H , CH 3), 1.9 (m,
_{4H, CH 2), 1.75 (} m, 4H, CH 2), 3.
62 (br, 2H, CH ₂ ), 1.2 (s, 3H, CH
₃ ) MS (El = 30 eV): M / Z = 407, M / Z = 3
28, M / Z = 271 Elemental analysis: Ir 47.2% (theoretical 47.16%), C 47.1% (theoretical 47.1)
5%), H 5.7% (theory, 5.69%) For comparison purposes, instead of the 1,5-dimethyl-1,5-cyclooctadiene compound, a 1,5-cyclooctadiene compound was used. A conventional organic iridium compound represented by the above structural formula (II) was synthesized under the same conditions except that it was used.

FIGS. 2 and 3 show thermogravimetric curves (temperature rising rate: 10 ° C./min, dry argon atmosphere) for evaluating the vaporization characteristics of the obtained organic iridium compound of the present invention and the conventional organic iridium compound.

[Evaporation of Iridium Thin Film] Using the organic iridium compound of the present invention and the conventional organic iridium compound, an iridium thin film was prepared by the apparatus shown in FIG.
The film thickness was measured every minute. The film thickness was measured from a cross-sectional SEM image of the film. The measurement results are shown in Table 1. The obtained iridium film was a highly pure iridium film having an oxygen content of <1% and a carbon content of <1%.

Substrate; 25 nm square Si substrate with TiN deposited by sputtering to a thickness of 100 nm Substrate temperature; 240 ° C. Vaporization temperature; 90 ° C. Pressure; 1.5 torr Carrier gas flow rate; 80 ccm Ar reaction gas Flow rate: 50 ccm H ₂

[0021]

[Table 1]

[Evaporation of Iridium Oxide Thin Film] The same procedure as in the above-mentioned evaporation of an iridium thin film was carried out except that the organic iridium compound of the present invention was used and the reaction gas was changed from hydrogen to oxygen, and the following conditions were used. An iridium oxide film was formed on a substrate on which an iridium thin film was formed to a thickness of 200 nm by forming an iridium film, and the film was analyzed by Auger spectroscopy. The amount of carbon in the iridium oxide film was <1. % Of the iridium oxide film having high purity.

Substrate: Ir (thickness: 200 nm) / sputtered TiN (thickness: 100 nm) / Si substrate Substrate temperature: 350 ° C. Vaporization temperature: 90 ° C. Pressure: 1.5 torr Carrier gas flow rate: 80 ccm Ar reaction gas flow rate 50 ccm O ₂ [Discussion] The following is clear from the results shown in FIGS. That is, the organic iridium compound of the present invention can be completely vaporized at a temperature from room temperature to about 165 ° C. On the other hand, when the vaporization of the conventional organic iridium compound is completed, about 8% of a residue is generated. ing. From this,
It is clear that the organic iridium compound of the present invention has excellent thermal stability during vaporization.

From Table 1, the following is clear. That is, the organic iridium compound of the present invention has a film thickness that increases at a substantially constant rate with respect to the film formation time, and its film formation rate is faster than that of the conventional organic iridium compound.
In the case of the conventional organic iridium compound, the tendency to decrease the film formation amount becomes remarkable from the time when the film formation time exceeds 30 minutes.

When the organic iridium compound of the present invention was used, no decomposed iridium was generated in the vaporization vessel of the apparatus shown in FIG. 1, whereas in the case of the conventional organic iridium compound, the decomposed iridium was not used. Was found. Thus, the organic iridium compound of the present invention is vaporized at a constant rate with respect to the film formation time without being decomposed in the vaporization vessel, and is more excellent in thermal stability and volatility during vaporization than the conventional organic iridium compound. It can be seen that this is an organic iridium compound.

In the organic iridium compound of the present invention,
When hydrogen is used as a reaction gas in forming a film, a high-purity iridium film can be formed, and when oxygen is used as a reaction gas, a high-purity iridium oxide film can be formed. By doing, easily,
Not only a single-layer film of iridium or iridium oxide,
A stacked film of an iridium thin film or an iridium oxide thin film can be formed over a substrate.

[0027]

As described in detail above, the iridium thin film and the organic iridium compound for forming an iridium oxide thin film formed by metalorganic chemical vapor deposition having a high vapor pressure according to the present invention are liquid at room temperature. The fixed amount of the vapor deposition material can be easily supplied by the liquid supply method. Moreover, since it has a stable vaporization rate and excellent thermal stability during vaporization, the MOCVD method
A uniform and dense high-purity iridium oxide thin film or iridium oxide thin film useful as a wiring material of a semiconductor device or the like can be efficiently manufactured.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an apparatus for explaining a thermal decomposition type MOCVD method.

FIG. 2 is a graph showing a thermogravimetric curve of the organic iridium compound of the present invention.

FIG. 3 is a graph showing a thermogravimetric curve of a conventional organic iridium compound.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Deposition raw material 2 Vaporization container 3 Heating furnace 4 Carrier gas introduction pipe 5 Reaction gas introduction pipe 6 Substrate 7 Heater 8 Reaction furnace 9 Vacuum piping

──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Katsumi Ogi 1-297 Kitabukuro-cho, Omiya City, Saitama Prefecture, Central Research Laboratory of Mitsubishi Materials Corporation (56) References JP-A-8-260148 (JP, A) JP JP-A-8-20870 (JP, A) JP-A-4-2211058 (JP, A) JP-A-3-235373 (JP, A) JP-A-6-290789 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) H01L 21/205 C07F 15/00 C23C 16/18 H01L 21/285

Claims (1)

(57) [Claims] 1. An organic iridium compound for forming a thin film of iridium or iridium oxide by chemical vapor deposition, wherein the organic iridium compound is represented by the following structural formula (I). Embedded image