RAW MATERIAL FOR CHEMICAL DEPOSITION CONTAINING ORGANORUTHENIUM COMPOUND, AND CHEMICAL DEPOSITION METHOD USING THE RAW MATERIAL FOR CHEMICAL DEPOSITION

Abstract

The present invention relates to a raw material of an organoruthenium compound for producing a ruthenium thin film or a ruthenium compound thin film by a chemical deposition method. This organoruthenium compound is an organoruthenium compound represented by the following Formula 1 and including a trimethylenemethane-based ligand (L.sub.1) and three carbonyl ligands coordinated to divalent ruthenium. In Formula 1, the trimethylenemethane-based ligand L.sub.1 is represented by the following Formula 2:

##STR00001## wherein a substituent R of the ligand L.sub.1 is hydrogen, or any one of an alkyl group, a cyclic alkyl group, an alkenyl group, an alkynyl group, and an amino group having a predetermined number of carbon atoms.

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, the raw material comprising: an organoruthenium compound represented by the following Formula 1 and comprising a trimethylenemethane-based ligand (L.sub.1) and three carbonyl ligands coordinated to divalent ruthenium:
RuL.sub.1(CO).sub.3  [Formula 1] wherein the trimethylenemethane-based ligand L.sub.1 is represented by the following Formula 2: ##STR00014## wherein a substituent R of the ligand L.sub.1 is any one of hydrogen, a linear or branched alkyl group having 1 or more and 8 or less carbon atoms, a cyclic alkyl group having 3 or more and 9 or less carbon atoms, a linear or branched alkenyl group having 2 or more and 8 or less carbon atoms, a linear or branched alkynyl group having 2 or more and 8 or less carbon atoms, a linear or branched amino group having 2 or more and 8 or less carbon atoms, and an aryl group having 6 or more and 9 or less carbon atoms.

2. The raw material for chemical deposition according to claim 1, wherein the substituent R of the ligand L.sub.1 is any one of a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, and a neopentyl group.

3. A chemical deposition method for a ruthenium thin film or a ruthenium compound thin film, comprising vaporizing a raw material containing an organoruthenium compound to obtain a raw material gas, and introducing the raw material gas together onto a substrate surface while heating the gas, wherein the method uses the raw material for chemical deposition according to claim 1 as the raw material, and uses hydrogen as a reaction gas.

4. The chemical deposition method according to claim 3, wherein the method comprises: applying a reducing gas as the reaction gas, and introducing the raw material gas onto the substrate surface together with the reaction gas, and heating the gases.

5. The chemical deposition method according to claim 4, wherein the reducing gas is a gas of any one of hydrogen, ammonia, hydrazine, formic acid, and an alcohol.

6. The chemical deposition method according to claim 3, wherein the method comprises: applying either of an oxidizing gas and a gas of an oxygen-containing reactant as the reaction gas, and introducing the raw material gas onto the substrate surface together with the reaction gas, and heating the gases.

7. The chemical deposition method according to claim 6, wherein the oxidizing gas is a gas of any one of oxygen and ozone, and the gas of an oxygen-containing reactant is a gas of any one of water and an alcohol.

8. The chemical deposition method according to claim 3, wherein a film forming temperature is 150° C. or more and 350° C. or less.

9. A chemical deposition method for a ruthenium thin film or a ruthenium compound thin film, comprising vaporizing a raw material containing an organoruthenium compound to obtain a raw material gas, and introducing the raw material gas together onto a substrate surface while heating the gas, wherein the method uses the raw material for chemical deposition according to claim 2 as the raw material, and uses hydrogen as a reaction gas.

10. The chemical deposition method according to claim 4, wherein a film forming temperature is 150° C. or more and 350° C. or less.

11. The chemical deposition method according to claim 5, wherein a film forming temperature is 150° C. or more and 350° C. or less.

12. The chemical deposition method according to claim 6, wherein a film forming temperature is 150° C. or more and 350° C. or less.

13. The chemical deposition method according to claim 7, wherein a film forming temperature is 150° C. or more and 350° C. or less.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] FIG. 1 is a diagram illustrating a DSC measurement result of an organoruthenium compound of Example 1;

[0057] FIG. 2 is a diagram illustrating a DSC measurement result of an organoruthenium compound of Example 2;

[0058] FIG. 3 is a diagram illustrating a DSC measurement result of an organoruthenium compound of Example 3;

[0059] FIG. 4 is a diagram illustrating a DSC measurement result of an organoruthenium compound of Example 4;

[0060] FIG. 5 is a diagram illustrating a DSC measurement result of an organoruthenium compound of Comparative Example 1;

[0061] FIG. 6 is a diagram illustrating TG curves of the organoruthenium compounds of Example 1 to Example 4 and Comparative Example 1 and Comparative Example 2;

[0062] FIG. 7 illustrates an SEM image of a cross section in the thickness direction of a ruthenium thin film of Example 1 formed in First Embodiment (reaction gas: hydrogen);

[0063] FIG. 8 illustrates an SEM image of a cross section in the thickness direction of a ruthenium thin film of Example 3 formed in First Embodiment (reaction gas: hydrogen);

[0064] FIG. 9 illustrates an SEM image of a cross section in the thickness direction of a ruthenium thin film of Example 1 formed in Second Embodiment (reaction gas: oxygen); and

[0065] FIG. 10 illustrates an SEM image of a cross section in the thickness direction of a ruthenium thin film of Example 3 formed in Second Embodiment (reaction gas: oxygen).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0066] First Embodiment: Now, a preferred embodiment of the present invention will be described. In the present embodiment, it was checked whether or not an organoruthenium compound of the present invention could be synthesized. Here, organoruthenium compounds in which trimethylenemethane (Example 1) coordinated as a trimethylenemethane-based ligand (L.sub.1), and in which trimethylenemethane-based ligands respectively having a substituent R of an ethyl group (Example 2), a propyl group (Example 3), an isobutyl group (Example 4), and an octyl group (Example 5) coordinated were synthesized. These organoruthenium compounds were evaluated for physical properties, and in addition, were used for performing a film formation test of a ruthenium thin film.

Synthesis of Organoruthenium Compound

Example 1: Synthesis of (η.SUP.4.-methylene-1,3-propanediyl)tricarbonyl Ruthenium

[0067] 50.0 g (97.5 mmol) of tricarbonyl-dichlororuthenium dimer was suspended in 1400 ml of tetrahydrofuran, and 300 ml of a solution of 27.0 g (214.5 mmol) of 3-chloro-2-(chloromethyl)-1-propene in tetrahydrofuran was added thereto. To the resultant, 12.0 g (479 mmol) magnesium turnings were slowly added, followed by stirring at room temperature for 8 hours. To the resultant reaction mixture, 10 mL of methanol was added for quenching, and the solvent was distilled off under reduced pressure. The thus obtained residue was extracted with 500 mL of pentane once, and subsequently with 250 mL of pentane twice, and the solvent was distilled off under reduced pressure. The thus obtained oil was purified by sublimation to obtain 17.0 g (71.1 mmol) of a colorless liquid as a target (yield: 36%). The synthesis reaction is as follows:

##STR00009##

Example 2: Synthesis of (η.SUP.4.-2-propylidene-1-yl,3-propanediyl)tricarbonyl Ruthenium

[0068] 12.2 g (24.0 mmol) of tricarbonyl-dichlororuthenium dimer was suspended in 420 ml of tetrahydrofuran, and 100 ml of a solution of 82.0 g (53.6 mmol) of 1-chloro-2-(chloromethyl)-2-pentene in tetrahydrofuran was added thereto. To the resultant, 4.4 g (192 mmol) magnesium turnings were slowly added, followed by stirring at room temperature for 3 hours. To the resultant reaction mixture, 12 mL of methanol was added for quenching, and the solvent was distilled off under reduced pressure. The thus obtained residue was extracted with 30 mL of pentane three times, and the solvent was distilled off under reduced pressure. The thus obtained oil was purified by distillation to obtain 4.84 g (18.1 mmol) of a colorless liquid as a target (yield: 38%). The synthesis reaction performed in this example is as follows:

##STR00010##

Example 3: Synthesis of (η.SUP.4.-2-butylidene-1,3-propanediyl)tricarbonyl Ruthenium

[0069] 6.12 g (12.0 mmol) of tricarbonyl-dichlororuthenium dimer was suspended in 200 ml of tetrahydrofuran, and 50 ml of a solution of 4.81 g (28.8 mmol) of 1-chloro-2-(chloromethyl)-2-hexene in tetrahydrofuran was added thereto. To the resultant, 22.7 g (96.0 mmol) magnesium turnings were slowly added, followed by stirring at room temperature for 3 hours. To the resultant reaction mixture, 6 mL of methanol was added for quenching, and the solvent was distilled off under reduced pressure. The thus obtained residue was extracted with 30 mL of pentane three times, and the solvent was distilled off under reduced pressure. The thus obtained oil was purified by distillation to obtain 27.9 g (9.92 mmol) of a colorless liquid as a target (yield: 41%). The synthesis reaction performed in this example is as follows:

##STR00011##

Example 4: Synthesis of (η.SUP.4.-2-(3-methylbutylidene-1,3-propanediyl)tricarbonyl Ruthenium

[0070] 6.12 g (12.0 mmol) of tricarbonyl-dichlororuthenium dimer was suspended in 200 ml of tetrahydrofuran, and 50 ml of a solution of 5.21 g (28.8 mmol) of 1-chloro-2-(chloromethyl)-5-methyl-2-hexene in tetrahydrofuran was added thereto. To the resultant, 2.2 g (96.0 mmol) magnesium turnings were slowly added, followed by stirring at room temperature for 3 hours. To the resultant reaction mixture, 6 mL of methanol was added for quenching, and the solvent was distilled off under reduced pressure. The thus obtained residue was extracted with 30 mL of pentane three times, and the solvent was distilled off under reduced pressure. The thus obtained oil was purified by distillation to obtain 2.12 g (7.18 mmol) of a colorless liquid as a target (yield: 30%). The synthesis reaction performed in this example is as follows:

##STR00012##

Example 5: Synthesis of (η.SUP.4.-2-nonylidene-1,3-propanediyl)tricarbonyl Ruthenium

[0071] 6.12 g (12.0 mmol) of tricarbonyl-dichlororuthenium dimer was suspended in 200 ml of tetrahydrofuran, and 50 ml of a solution of 6.83 g (28.8 mmol) of 1-chloro-2-(chloromethyl)-2-undecene in tetrahydrofuran was added thereto. To the resultant, 2.2 g (96.0 mmol) magnesium turnings were slowly added, followed by stirring at room temperature for 3 hours. To the resultant reaction mixture, 6 mL of methanol was added for quenching, and the solvent was distilled off under reduced pressure. The thus obtained residue was extracted with 30 mL of pentane three times, and the solvent was distilled off under reduced pressure. The thus obtained oil was purified by distillation to obtain 3.37 g (9.60 mmol) as a target (yield: 40%). The synthesis reaction performed in this example is as follows:

##STR00013##

[0072] In this manner, it was confirmed in the present embodiment that the organoruthenium compounds having, as the substituent R, hydrogen and the hydrocarbon groups having 1 to 8 carbon atoms can be synthesized.

[0073] [Evaluation of Physical Properties]

[0074] Regarding the compounds of Example 1 to Example 5 among the organoruthenium compounds synthesized in the present embodiment, various physical properties (a melting point, a decomposition temperature, and a vaporization property) were studied and evaluated.

[0075] (I) Study of Melting Point

[0076] The organoruthenium compound of each example was subjected to differential scanning calorimetry (DSC) to measure a melting point and a decomposition temperature. The DSC was performed with DSC3500-ASC manufactured by NETZSCH used as a measurement apparatus with the weight of a sample set to 1.0 mg, nitrogen used as a carrier gas, at a scanning rate of 10° C./min, and with a measurement temperature range set to −60° C. to 400° C. The DSC was also performed, for comparison, on (1,3-cyclohexadiene)tricarbonyl ruthenium of the conventional technique (Formula 2 described above; referred to as Comparative Example 1). Results of the DSC of the respective organoruthenium compounds of Example 1 to Example 4 and Comparative Example 1 are illustrated in FIG. 1 to FIG. 5.

[0077] As a result of the DSC, a peak corresponding to the melting point was observed at 21.5° C. in the organoruthenium compound of Example 1 (R=hydrogen). On the other hand, in the DSC of the organoruthenium compounds of Example 2 (R=methyl group), Example 3 (R=ethyl group), and Example 4 (R=isobutyl group), no signal corresponding to the melting point was found in the measurement temperature range having a lower limit of −60° C.

[0078] It was confirmed, based on the results of the DSC described above, that all of the organoruthenium compounds of the present embodiment can be dealt with in a liquid state at normal temperature (about 25° C.). In addition, it was found that the organoruthenium compounds of Example 2 to Example 4 in which the substituents (ethyl, propyl and isobutyl) are introduced into trimethylenemethane have melting points largely lower than that of Example 1 containing no substituent. It is deemed that the organoruthenium compounds of these examples are compounds capable of further stably retaining the liquid state at normal temperature. It was confirmed that when a hydrocarbon group is introduced into trimethylenemethane, handleability of the raw material for chemical deposition in film formation process can be improved. It is noted that the melting point of the organoruthenium compound of Comparative Example 1 was 24.6° C., which was substantially the same melting point as that of Example 1.

[0079] (II) Study of Thermal Stability

[0080] Based on the analysis results of the DSC, the decomposition temperature of each organoruthenium compound can be measured. The decomposition temperatures of the respective organoruthenium compounds measured by the DSC are as follows.

TABLE-US-00001 TABLE 1 Decomposition Substituent R of L1 temperature Example 1 Hydrogen 282.2° C. Example 2 Ethyl group 243.4° C. Example 3 Propyl group 285.8° C. Example 4 Isobutyl group 285.2° C. Comparative — 190.1° C. Example 1

[0081] As described above, the decomposition temperature of the conventional compound of (1,3-cyclohexadiene)tricarbonyl ruthenium (Comparative Example 1) is 190.1° C. On the other hand, the organoruthenium compounds of Example 1 to Example 4 in each of which the trimethylenemethane-based ligand (L.sub.1) coordinates have higher decomposition temperatures as compared with that of Comparative Example 1, and it is deemed that these compounds are excellent in thermal stability. When Example 1 using hydrogen as the substituent R is compared with Example 2 to Example 4 each having the hydrocarbon group introduced as the substituent, the decomposition temperature is lower than in Example 1 in Example 2 having an ethyl group introduced. The decomposition temperatures are higher in Example 3 having a propyl group introduced and in Example 4 having an isobutyl group introduced. The number of carbon atoms of the substituent varies the decomposition temperature, but a simple trend is not found, and it is presumed that the decomposition temperature is affected also by the presence of a branch chain in the complex, the three-dimensional structure and the like.

[0082] (III) Study of Vaporization Property (Vapor Pressure)

[0083] Next, regarding the organoruthenium compounds of Example 1 to Example 4, the vaporization property was studied through thermogravimetric-differential thermal analysis (TG-DTA). In the TG-DTA, TG-DTA2000SA manufactured by BRUKER was used, a sample with a weight of 5 mg was filled in an aluminum cell, and change in a calorific value and a weight was observed in a nitrogen atmosphere, at a temperature increase rate of 5° C./min in a measurement temperature range of from room temperature to 500° C. In the study by the TG-DTA, for comparison, the organoruthenium compound of Comparative Example 1 ((1,3-cyclohexadiene)tricarbonyl ruthenium) and dicarbonyl-bis(5-methyl-2,4-hexanediketonato)ruthenium (Formula 5 described above; referred to as Comparative Example 2) also of the conventional technique were subjected to the measurement.

[0084] TG curves of the organoruthenium compounds of Example 1 to Example 4 and Comparative Examples are illustrated in FIG. 5. It is understood that all the organoruthenium compounds of Example 1 to Example 4 in which the trimethylenemethane-based ligands coordinate have higher vapor pressures than that of Comparative Example 2 (dicarbonyl-bis(5-methyl-2,4-hexanediketonato)ruthenium), and rapidly vaporize. Besides, also as compared with Comparative Example 1 ((1,3-cyclohexadiene)tricarbonyl ruthenium), the organoruthenium compounds of Example 1 to Example 3 have higher vapor pressures. It is deemed that Example 4 and Comparative Example 1 are equivalent in the vapor pressure. Accordingly, it is deemed that the organoruthenium compounds of the present embodiment have a good vaporization property from the viewpoint of the vapor pressure.

[0085] When Example 1 to Example 4 are compared with one another, the compound of Example 1 in which no hydrocarbon group is introduced as the substituent, and in which trimethylenemethane coordinates has the highest vapor pressure, and easily vaporizes. In other words, it is understood that when a substituent is introduced and a molecular weight is increased, the vapor pressure is liable to lower. In the TG-DTA measurement of Example 1, however, the sample started to vaporize at the same time as the sample was set, and hence it is deemed that the vapor pressure was rather too high. Therefore, it is presumed that introduction of a substituent into the trimethylenemethane ligand may be effective from the viewpoint of vapor pressure adjustment in some cases.

[0086] Based on the evaluation results of the physical properties, it was confirmed that the organoruthenium compound of the present invention in which the trimethylenemethane-based ligand coordinates is in the form of a liquid and hence is excellent in handleability, and has a favorable vapor pressure and a useful vaporization property, and on the other hand, has a decomposition temperature of 200° C. or more, and has adequate thermal stability, and hence is suitable as a raw material for chemical deposition.

[0087] [Film Formation Test]

[0088] The organoruthenium compounds of Example 1 (R=hydrogen) and Example 3 (R=propyl group) of the present embodiment were subjected to a film formation test to study whether or not a ruthenium thin film could be formed. Besides, for comparison, dicarbonyl-bis(5-methyl-2,4-hexanediketonato)ruthenium (Formula 5, Patent Document 4) of a conventional raw material for chemical deposition was also subjected to the film formation test (Comparative Example 2).

[0089] With the organoruthenium compound of the present embodiment used as a raw material, a ruthenium thin film was formed with a CVD apparatus (hot wall CVD film forming apparatus). Film forming conditions were as follows:

[0090] Substrate material: Si

[0091] Carrier gas (nitrogen gas): 10 sccm, 200 sccm

[0092] Reaction gas (hydrogen gas): 10 sccm, 200 sccm

[0093] Film forming pressure: 30 torr, 50 torr

[0094] Film forming time: 15 min, 30 min

[0095] Film forming temperature: 190° C., 200° C., 210° C., 230° C., 250° C.

[0096] A ruthenium thin film was formed under the above-described conditions, and a thickness and a resistance value of the resultant were measured. The thickness of the ruthenium thin film was obtained by measuring thicknesses in a plurality portions based on a result of XRF (X-ray reflection fluorescence) using EA1200VX manufactured by Hitachi High-Tech Science Corporation, and calculating an average of the thicknesses. Besides, the resistance value was measured by a four point probe method. Results of the measurement are shown in Table 2. FIG. 6 and FIG. 7 illustrate results of observation, with a scanning electron microscope (SEM), of cross sections in the thickness direction of the ruthenium thin films of Example 1 and Example 3.

TABLE-US-00002 TABLE 2 Film Film Film Nitrogen Hydrogen forming forming forming Ru Specific Substrate gas gas pressure time temperature thickness resistance Sample material (sccm) (sccm) (torr) (min) (° C.) (nm) (μΩ .Math. cm) Example 1 Si 10 10 30 15 190 4.22 13.4 200 5.21 15.4 Example 3 200 200 50 190 2.46 34.6 210 4.76 40.2 230 7.65 43.1 Comparative 10 200 30 250 17.8 65.8 Example 2

[0097] As illustrated in FIG. 7 and FIG. 8, it can be confirmed that the organoruthenium compounds of Example 1 and Example 3 can form uniform ruthenium thin films having smooth surfaces. Thus, it was confirmed that the organoruthenium compounds of Example 1 and Example 3 can form a ruthenium thin film having a sufficient thickness in a short period of time. Besides, as compared with the film forming conditions for the organoruthenium compound of Comparative Example 2, it is understood that the organoruthenium compound of each example can form a film at a lower temperature. The organoruthenium compound of the present invention has high reactivity with hydrogen used as the reaction gas, and enables efficient film formation.

[0098] Besides, regarding the quality of the thin film, it can be confirmed that a high quality ruthenium thin film having largely lower specific resistance as compared with that of Comparative Example 2 is formed. The organoruthenium compound of the present invention does not contain an oxygen atom capable of directly coordinating to ruthenium and have good reactivity with hydrogen or the like differently from the organoruthenium compound of Comparative Example 2 containing the β-diketonato ligand. Therefore, a possibility of oxygen mixture in the ruthenium thin film is low, and hence a high quality ruthenium thin film having low specific resistance can be formed.

[0099] Second Embodiment: In this embodiment, the organoruthenium compounds of Example 1 (R=hydrogen), Example 3 (R=propyl group) and Comparative Example 2 of First Embodiment were used as a raw material, and oxygen was applied as the reaction gas to perform a film formation test of a ruthenium thin film. For the film formation, the same CVD apparatus (hot wall CVD film forming apparatus) as that used in First Embodiment was used. Film forming conditions were as follows:

[0100] Substrate material: Si

[0101] Carrier gas (nitrogen gas): 10 sccm, 50 sccm

[0102] Reaction gas (oxygen gas): 10 sccm

[0103] Film forming pressure: 1 torr, 2 torr, 3 torr

[0104] Film forming time: 15 min, 30 min

[0105] Film forming temperature: 190° C., 210° C., 250° C.

[0106] A ruthenium thin film was formed under the above-described conditions, and a thickness and a resistance value of the resultant were measured. The methods for measuring the thickness and the resistance value of the ruthenium thin film were the same as those employed in First Embodiment. Results of the measurement are shown in Table 3. Besides, FIG. 9 and FIG. 10 respectively illustrate SEM images of the ruthenium thin films of Example 1 and Example 3.

TABLE-US-00003 TABLE 3 Film Film Film Nitrogen Oxygen forming forming forming Ru Specific Substrate gas gas pressure time temperature thickness resistance Sample material (sccm) (sccm) (torr) (min) (° C.) (nm) (μΩ .Math. cm) Example 1 Si 10 10 1 15 190 25.3 20.2 Example 3 50 3 210 24.8 25.8 Comparative 10 2 30 250 21.6 46.4 Example 2

[0107] It is understood, based on Table 3, FIG. 8 and FIG. 9, that the organoruthenium compounds of Example 1 and Example 3 can form a ruthenium thin film even with oxygen used as the reaction gas. Also in the present embodiment, a uniform ruthenium thin film having a smooth surface is formed. Besides, the organoruthenium compounds of Example 1 and Example 3 can form a ruthenium thin film at a lower temperature and a higher deposition rate than the organoruthenium compound of Comparative Example 2. When the thus formed ruthenium thin films are compared in the specific resistance, the ruthenium thin films of Example 1 and Example 3 have specific resistance extremely lower than that of the ruthenium thin film of Comparative Example 2. This is probably because the organoruthenium compounds of Example 1 and Example 3 suppress generation of a ruthenium oxide even with oxygen used as the reaction gas.

INDUSTRIAL APPLICABILITY

[0108] An organoruthenium compound contained in a raw material for chemical deposition of the present invention has high thermal stability, and can form a ruthenium thin film even with a reducing gas such as hydrogen used as a reaction gas. Besides, even when oxygen is used as the reaction gas, it can form a good ruthenium thin film. The raw material for chemical deposition of the present invention has a favorable vapor pressure, and is good also in handleability. The present invention is suitable for use as a wiring/electrode material of a semiconductor device such as a DRAM.