RAW MATERIAL FOR CHEMICAL DEPOSITION CONTAINING RUTHENIUM COMPLEX, AND CHEMICAL DEPOSITION METHOD USING THE RAW MATERIAL FOR CHEMICAL DEPOSITION

Abstract

The present invention relates to a raw material for chemical deposition for producing a ruthenium thin film or a ruthenium compound thin film by a chemical deposition method, containing a ruthenium complex represented by the following Chemical Formula 1. In Chemical Formula 1, ligands L.sub.1 and L.sub.2 coordinated to ruthenium are represented by the following Chemical Formula 2. The raw material for chemical deposition according to the present invention can be formed into a high quality thin film even if a reaction gas containing an oxygen atom is not used.

##STR00001## wherein R.sub.1 to R.sub.12, which are substituents of the ligands L.sub.1 and L.sub.2, are each independently any one of a hydrogen atom, and a linear or branched alkyl group having a carbon number of 1 or more and 4 or less.

Claims

1. A raw material for chemical deposition for producing a ruthenium thin film or a ruthenium compound thin film by a chemical deposition method, comprising a ruthenium complex represented by the following Chemical Formula 1:
RuL.sub.1L.sub.2  [Chemical Formula 1] wherein ligands L.sub.1 and L.sub.2 coordinated to ruthenium are represented by the following Chemical Formula 2: ##STR00023## wherein R.sub.1 to R.sub.12, which are substituents of the ligands L.sub.1 and L.sub.2, are each independently any one of a hydrogen atom, and a linear or branched alkyl group having a carbon number of 1 or more and 4 or less.

2. The raw material for chemical deposition according to claim 1, wherein in substituents R.sub.1 to R.sub.6 of the ligand L.sub.1, all of R.sub.1 to R.sub.6 are a hydrogen atom, or R.sub.1 is an ethyl group and R.sub.2 to R.sub.6 are a hydrogen atom.

3. The raw material for chemical deposition according to claim 1, wherein in substituents R.sub.7 to R.sub.12 of the ligand L.sub.2, all of R.sub.7 to R.sub.12 are a hydrogen atom, R.sub.7 is a methyl group and R.sub.8 to R.sub.12 are a hydrogen atom, R.sub.7 is an ethyl group and R.sub.8 to Ru are a hydrogen atom, or R.sub.7 is a methyl group, R.sub.10 is a 1-methylethyl group, and R.sub.8, R.sub.9, R.sub.11 and R.sub.12 are a hydrogen atom.

4. A chemical deposition method of a ruthenium thin film or a ruthenium compound thin film, wherein the method comprising vaporizing a raw material comprising a ruthenium complex to obtain a raw material gas, and introducing the raw material gas onto a substrate surface while heating to decompose the ruthenium complex, wherein the raw material for chemical deposition defined in claim 1 is used as the raw material.

5. The chemical deposition method according to claim 4, wherein a reducing gas is used as a reaction gas.

6. The raw material for chemical deposition according to claim 2, wherein in substituents R.sub.7 to R.sub.12 of the ligand L.sub.2, all of R.sub.7 to R.sub.12 are a hydrogen atom, R.sub.7 is a methyl group and R.sub.8 to R.sub.12 are a hydrogen atom, R.sub.7 is an ethyl group and R.sub.8 to R.sub.12 are a hydrogen atom, or R.sub.7 is a methyl group, R.sub.10 is a 1-methylethyl group, and R.sub.8, R.sub.9, R.sub.11 and R.sub.12 are a hydrogen atom.

7. A chemical deposition method of a ruthenium thin film or a ruthenium compound thin film, wherein the method comprising vaporizing a raw material comprising a ruthenium complex to obtain a raw material gas, and introducing the raw material gas onto a substrate surface while heating to decompose the ruthenium complex, wherein the raw material for chemical deposition defined in claim 2 is used as the raw material.

8. A chemical deposition method of a ruthenium thin film or a ruthenium compound thin film, wherein the method comprising vaporizing a raw material comprising a ruthenium complex to obtain a raw material gas, and introducing the raw material gas onto a substrate surface while heating to decompose the ruthenium complex, wherein the raw material for chemical deposition defined in claim 3 is used as the raw material.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0039] FIG. 1 is a diagram showing the results of TG-DTA of ruthenium complexes of Examples 1 and 2 performed under a nitrogen atmosphere; and

[0040] FIG. 2 is a diagram showing the results of TG-DTA of the ruthenium complexes of Examples 1 and 2 performed under a hydrogen atmosphere.

DESCRIPTION OF EMBODIMENTS

[0041] Now, the best embodiment of the present invention will be described. In the present embodiment, two ruthenium complexes respectively using a trimethylenemethane derivative and a benzene as ligands were synthesized, thermal characteristics of the complexes were evaluated, and a film formation test for forming a ruthenium thin film was carried out.

[0042] [Synthesis of Complexes]

Example 1: Synthesis of (Methylene-1,3-propanediyl)[1-methyl-4-(1-methylethyl)benzene]ruthenium

[0043] As a ruthenium complex of Example 1, (methylene-1,3-propanediyl)[1-methyl-4-(1-methylethyl)benzene]ruthenium having the following structural formula was synthesized.

##STR00018##

[0044] 12.24 g (20 mmol) of di-μ-chlorodichlorobis[1-methyl-4-(1-methylethyl)benzene]diruthenium, 6.0 g (60 mmol) of 3-chloro-2-(chloromethyl)-1-propene, and 3.89 g (160 mmol) of magnesium were placed in a flask holding 320 ml of tetrahydrofuran (THF) as a solvent followed by reaction at room temperature for 3 hours. After the reaction, the solvent was distilled off under reduced pressure, and purification was conducted using an alumina column containing hexane as a developer solvent. Distillation purification was further conducted to obtain 4.0 g (13.8 mmol) of a target product of (methylene-1,3-propanediyl)[1-methyl-(1-methylethyl)benzene]ruthenium (yield: 35%). At this point, the reaction formula is as follows:

##STR00019##

Example 2: Synthesis of Benzene(methylene-1,3-propanediyl)ruthenium

[0045] As a ruthenium complex of Example 2, benzene(methylene-1,3-propanediyl)ruthenium having the following structural formula was synthesized.

##STR00020##

[0046] 0.45 g (0.89 mmol) of bis(benzene)di-μ-chlorodichlorodiruthenium and 0.8 g (2.10 mmol) of 2-methylene-1,3-bis(trimethylstannyl)propane were placed in a flask holding 50 ml of tetrahydrofuran (THF) as a solvent, followed by reaction at room temperature for 30 hours. After the reaction, the solvent was distilled off under reduced pressure, and purification was conducted using an alumina column containing toluene as a developer solvent. Recrystallization from pentane was further conducted to obtain 0.18 g (0.77 mmol) of a target product of benzene(methylene-1,3-propanediyl)ruthenium (yield: 42%). At this point, the reaction formula is as follows:

##STR00021##

Comparative Example: Synthesis of Bis(ethylcyclopentadienyl)ruthenium

[0047] As a Comparative Example of the ruthenium complexes of Examples 1 and 2, bis(ethylcyclopentadienyl)ruthenium having the structural formula of the above-described Chemical Formula 1 was synthesized. 28.04 g (0.43 mol) of a zinc powder, 9.3 g (0.10 mol) of ethylcyclopentadiene, and 10.94 g (0.04 mol) of ruthenium trichloride were placed in a flask holding 131.5 ml of ethanol as a solvent, followed by reaction at −35° C. The resultant reaction solution was extracted with hexane and purified to obtain 11.74 g (0.04 mmol) of a target product of bis(ethylcyclopentadienyl)ruthenium (yield: 94%). At this point, the reaction formula is as follows:

##STR00022##

[0048] [Differential Scanning Calorimetry] The ruthenium complexes of Examples 1 and 2 synthesized in the present embodiment were subjected to differential scanning calorimetry (DSC) to estimate a decomposition temperature. For analysis, a differential scanning calorimeter (DSC3500-ASC manufactured by NETZSCH) was used. A sealable aluminum pan was filled with a complex sample (weight: 1 mg), and DSC was observed under nitrogen atmosphere at a temperature increasing rate of 10° C./min in a measurement temperature range of −50° C. to 400° C. Then, a decomposition temperature was estimated based on an exothermic reaction. As a result of the DSC, the decomposition temperature of the ruthenium complex of Example 1 was measured as 198° C. The decomposition temperature of the ruthenium complex of Example 2 was measured as 228° C. It was found that the ruthenium complex of Example 1 was lower in thermal stability and was easily decomposed.

[0049] The ruthenium complex of Comparative Example was also subjected to the DSC, and the decomposition temperature of the complex of Comparative Example was 364° C. It was thus confirmed that the decomposition temperatures of the ruthenium complexes of Examples 1 and 2 were largely lower than that of the ruthenium complex of Comparative Example.

[0050] [Thermogravimetry]

[0051] The ruthenium complexes of Examples 1 and 2 were subjected to thermogravimetry-differential thermal analysis (TG-DTA) under nitrogen atmosphere and under hydrogen atmosphere respectively to examine decomposition characteristics in more detail. In this test, TG-DTA2000SA manufactured by BRUKER was used as an analysis apparatus, an aluminum cell was filled with a ruthenium complex sample (sample weight: 5 mg), and weight change was observed at a temperature increasing rate of 5° C./min in a measurement temperature range of room temperature to 400° C.

[0052] The measurement results of the ruthenium complexes of Examples 1 and 2 performed with TG-DTA under nitrogen atmosphere are illustrated in FIG. 1. According to the results, the complex of Example 1 is vaporized without forming a residue up to 188° C. It is thus found that this complex is thermally decomposed at 188° C. or more. On the other hand, vaporization of the complex of Example 2 is completed when the temperature is increased to 200° C. It is deemed that this complex is thermally decomposed at 200° C. or more. The temperatures of thermal decomposition estimated based on this thermogravimetry accord with the results of the DSC described above.

[0053] The measurement results of the ruthenium complexes of the respective Examples performed under hydrogen atmosphere with TG-DTA are illustrated in FIG. 2. Under hydrogen atmosphere, the vaporization of the ruthenium complex of Example 1 is completed at 148° C. with a residue formed. The vaporization of the ruthenium complex of Example 2 is completed at 172° C. with a residue formed. It is thus understood that both the complexes are vaporized and thermally decomposed at a lower temperature when the hydrogen atmosphere is employed.

[0054] Based on the results of FIGS. 1 and 2, there is no specific peak during the vaporization in thermogravimetric curves of the complexes of Examples 1 and 2. Therefore, it can be confirmed that both the complexes are smoothly vaporized by heating to an appropriate temperature. Also under hydrogen atmosphere, a vaporization characteristic of similar trends was found. In comparison between Examples 1 and Example 2, however, it is deemed that the vaporization characteristic is better in Example 1. This is because the complex of Example 1 is reduced in weight at a lower temperature and the vaporization is completed at a lower temperature.

[0055] Weight reduction observed in thermogravimetry encompasses both weight reduction due to vaporization and weight reduction due to decomposition. A residue is formed through decomposition. Accordingly, it is deemed that a complex whose weight reduction is completed at a lower temperature and a complex forming a larger amount of a residue are complexes easily decomposed. When the measurement results obtained under hydrogen atmosphere of FIG. 2 are examined from this point of view, the complex of Example 1 forms a larger amount of residue at a lower temperature (148° C.) as compared with the complex of Example 1. Therefore, it is deemed that the complex of Example 1 is more easily decomposed under hydrogen atmosphere, and is a suitable complex.

[0056] [Film Formation Test]

[0057] Next, each of the ruthenium complexes of Examples 1 and 2 and Comparative Example was used as a raw material to form a ruthenium thin film with a CVD apparatus (hot wall CVD apparatus). Film formation conditions are described below, and after forming a ruthenium thin film, a film thickness and a specific resistance of the thin film were measured. For measuring the film thickness, a result observed with EA1200VX, manufactured by Hitachi High-Tech Science Corporation was used. As a method/conditions for measuring a specific resistance, MCP-T370, manufactured by Mitsubishi Chemical Analytech Co Ltd. was used for performing the measurement by a four probe method. The results of this film formation test are shown in Table 2.

[0058] Substrate: Si

[0059] Film forming temperature: 250° C.

[0060] Sample temperature (vaporization temperature): 55° C.

[0061] Film forming pressure: 5 torr

[0062] Reaction gas (carrier gas): hydrogen gas

[0063] Gas flow rate: 20 sccm

[0064] Film forming time: 30 min

TABLE-US-00002 TABLE 2 Ruthenium Specific Thickness Resistance Example 1 7.8 nm 36.4 μΩ .Math. cm Example 2 13.9 nm 60.0 μΩ .Math. cm Comparative — — Example

[0065] It was confirmed, based on Table 2, that a ruthenium thin film can be formed with a hydrogen gas used as a reaction gas when the ruthenium complexes of Examples 1 and 2 were used. On the contrary, when the ruthenium complex of Comparative Example was used, a ruthenium thin film failed to be formed with a hydrogen gas, and a specific resistance could not be measured.

[0066] Next, the ruthenium complex of Example 1 was applied to perform a film formation test with a film forming temperature set to 150° C. and 200° C. The film formation conditions were the same as those described above, and a film thickness and a specific resistance of a resultant ruthenium thin film were measured in the same manner as described above. The results of this film formation test are shown in Table 3. In Table 3, the results of the film formation of Example 1 at 250° C. (Table 2) are also shown.

TABLE-US-00003 TABLE 3 Film Forming Ruthenium Specific Temperature Thickness Resistance 250° C. 7.8 nm 36.4 μΩ .Math. cm 200° C. 8.7 nm 55.6 μΩ .Math. cm 150° C. 11.4 nm 86.6 μΩ .Math. cm

[0067] It is understood, from Table 3, that the ruthenium complex of Example 1 can be a raw material compound of a ruthenium thin film formed in a wide temperature range of 150° C. to 250° C. with a hydrogen gas used as a reaction gas. In particular, it was confirmed to be applicable to low temperature film formation at 150° C.

INDUSTRIAL APPLICABILITY

[0068] In a raw material for chemical deposition according to the present invention, a ruthenium complex constituting the raw material has thermal stability in an appropriate range, and hence, a ruthenium-containing thin film having a good quality can be produced even if a hydrogen gas is used as a reaction gas. The present invention is suitably used as a thin film electrode material of a semiconductor device such as a DRAM or an FERAM.