Coating processes – Coating by vapor – gas – or smoke – Metal coating
Reexamination Certificate
1998-06-15
2001-03-27
Meeks, Timothy (Department: 1762)
Coating processes
Coating by vapor, gas, or smoke
Metal coating
C427S255310, C556S136000
Reexamination Certificate
active
06207232
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process for producing a bis(ethylcyclopentadienyl)ruthenium complex and a bis(isopropylcyclopentadienyl)ruthenium complex and a process for producing ruthenium-containing films by the chemical vapor deposition method (hereinafter referred to simply as “the CVD method”) by using the same.
BACKGROUND OF THE INVENTION
With the recent tendency toward ultra-large-scale integrated circuits (ULSI), studies are under way to develop (Ba, Sr)TiO
3
films having high dielectric constants as capacitors and Ru and/or RuO
2
films are frequently employed as electrodes thereof. It has been a practice to produce these Ru films by the Ru metal sputtering method, while the RuO
2
films are produced by the reactive sputtering method of Ru metal in many cases. In further microscaled cases, however, it is expected that the desired step coverage or mass-productivity can be achieved by the CVD method. As the volatile ruthenium compounds to be used in the CVD method, investigations are in progress on tris(dipivaloylmethanato)ruthenium Ru(dpm)
3
and bis(cyclopentadienyl)ruthenium Ru(C
5
H
5
)
2
. Nakabayashi et al. reported that an Ru film was formed on an Si substrate at 600° C. by using Ru(dpm)
3
by the CVD method and then oxygen was introduced thereinto to give an RuO
2
film on the Ru [Proceedings of the 55th Symposium of Applied Physics in Autumn of 1994, p. 347, 19p-M-9 (1994)]. However, Ru(dpm)
3
has a melting point of 168° C. and thus occurs as solid crystals at room temperature. Because of having a vapor pressure of 0.1 Torr at about 136° C., it is supplied via sublimation.
D. E. Trent, B. Paris and H. H. Krause reported that a ruthenium metallic specular film with a purity of 99.99% was formed on a vycor glass substrate at 595° C. by the CVD method by supplying the sublimated vapor from Ru(C
5
H
5
)
2
maintained at 94° C. together with hydrogen gas [Inorg. Chem., 3, 1057 (1964)].
W.-C. Shin and S.-G. Yoon reported that Ru(C
5
H
5
)
2
was subjected to CVD at about 350° C. in an oxygen gas to thereby form an RuO
2
film of 200 nm on an SiO
2
/Si, MgO substrate [9th International Symposium on Integrated Ferroelectrics (Santa Fe, N. Mex. March, 1997), p. 104].
U.S. Pat. No. 5,130,172 has disclosed a process for coating a substrate with a metal comprising: maintaining the substrate at a temperature up to 190° C.; exposing this substrate to a vaporized organometallic compound represented by the formula L
n
MR
m
obtained by heating to a temperature up to 100° C.; then exposing the substrate to a hydrogen gas at a temperature up to 100° C.; and reacting the organometallic compound with hydrogen to thereby form a metal film. In the above formula L
n
MR
m
, L is hydrogen, ethylene, allyl, methylallyl, butadienyl, pentadienyl, cyclopentadienyl, methylcyclopentadienyl, cyclohexadienyl, hexadienyl, cycloheptatrienyl or a derivative of these compounds having at least one alkyl side chain having less than five carbon atoms; M is a metal that can readily cycle between two oxidation states and can catalyze hydrogenation of hydrocarbon ligands; R is methyl, ethyl, propyl or butyl; n is an integer from 0 to the valence of the metal; m is an integer from 0 to the valence of the metal; and m plus n must equal the valence of the metal. The cyclopentadienylruthenium compounds given in the claims specifying the same are cyclopentadienyl(methylcyclopentadienyl)ruthenium (C
2
H
5
)Ru(C
5
H
4
CH
3
), ruthenocenylacetylene (C
5
H
5
)Ru(C
5
H
4
CCH), ethenylruthenocene (C
2
H
5
)Ru(C
5
H
4
CHCH
2
), bis(methylcyclopentadienyl)ruthenium Ru(C
5
H
4
CH
3
)
2
and ethylruthenocene (C
5
H
5
)Ru(C
5
H
4
CH
2
CH
3
).
Table 1 shows the melting point of each of the compounds cited above shown in Dictionary of Organometallic Compounds, vol. 3 (2nd Ed., 1966, Chapman & Hall). Namely, all of these compounds except ethylruthenocene are solids at room temperature of 25° C.
TABLE 1
M.p. (° C.)
bis(cyclopentadienyl)ruthenium Ru (C
5
H
5
)
2
199-200
bis(methylcyclopentadienyl)ruthenium Ru (C
5
H
4
CH
3
)
2
61-63
cyclopentadienyl(methylcyclopentadienyl)-
41-42
ruthenium (C
5
H
5
) Ru (C
5
H
4
CH
3
)
ethenocenylacetylene (C
5
H
5
) Ru (C
5
H
4
CCH)
73-74
ethenylruthenocene (C
5
H
5
) Ru (C
5
H
4
CHCH
2
)
53.5-54.5
ethylruthenocene (C
5
H
5
) Ru (C
5
H
4
CH
2
CH
3
)
12-12.5
The supply of the starting compound via sublimation in the CVD method is inferior in quantitative supply, controllability and mass-productivity to the liquid supply system or evaporation supply system with the use of a carrier gas bubbling into the liquid. Accordingly, it is required to employ a starting compound which is a liquid at the step of supply at room temperature and has a sufficient vapor pressure. Moreover, it is necessary that the starting compound can be easily produced on a mass scale. Among the known cyclopentadienylruthenium compounds capable of forming an Ru film by the CVD method, none but ethylruthenocene is a liquid at room temperature of 55° C. and has a vapor pressure.
However, ethylruthenocene is poor in mass-productiveness. According to V. Mark and M. D. Raush ethylruthenocene is synthesized by reducing cyclopentadienyl(acetylcyclopentadienyl)ruthenium Ru(C
5
H
5
)(C
5
H
4
COCH
3
) with LiAlH
4
+AlCl
3
in diethyl ether [Inorg. Chem., vol. 3, 1067 (1964)]. Namely, it is necessary to use a specific cyclopentadienylruthenium compound as an intermediate, which brings about problems in mass-productiveness and production cost. That is to say, there has been known so far no cyclopentadienylruthenium compound which can be easily produced on a mass scale, is a liquid at room temperature and has a sufficient vapor pressure.
An object of the present invention is to specify cyclopentadienylruthenium compounds which are liquids at room temperature of 25° C., have sufficient vapor pressures, can be easily produced on a mass scale and are usable in forming Ru and RuO
2
films by the CVD method and provide a process for forming Ru and RuO
2
films by the CVD method with the use of these compounds. Another object of the present invention is to provide a process for producing these specific compounds being excellent in mass-productivity.
SUMMARY OF THE INVENTION
The present inventor has been studying the synthesis of organometallic compounds and CVD with the use of the same for a long time. To solve the above problems, the inventor synthesized and purified bis(ethylcyclopentadienyl)ruthenium Ru(C
2
H
5
C
5
H
4
)
2
, which is a publicly known compound with an undetermined melting point, and bis(isopropylcyclopentadienyl)ruthenium Ru(iC
3
H
7
C
5
H
4
)
2
, and measured the melting points and vapor pressures thereof. As a result, they revealed that these compounds have favorable physical properties. Then they formed Ru and RuO
2
films by the CVD method with the use of these compounds and thus found out that stable and good films could be obtained thereby, thus completing the present invention. Accordingly, the present invention has been established based on the finding that bis(ethylcyclopentadienyl)ruthenium Ru(C
2
H
5
C
5
H
4
)
2
and bis(isopropylcyclopentadienyl)ruthenium Ru(iC
3
H
7
C
5
H
4
)
2
are usable as the material which is a liquid at room temperature of 25° C. to be used in forming Ru and RuO
2
films by the CVD method.
Although bis(ethylcyclopentadienyl)ruthenium is a known compound processes for the synthesis of which are disclosed in two reports, its melting point has never been reported so far. One of the processes for synthesizing this compound comprises reducing bis(acetylcyclopentadienyl)ruthenium Ru(C
5
H
4
COCH
3
)
2
with NaBH
4
—H
2
SO
4
[G. B. Shul'pin, Zh. Obsch. Khim., 51, 2152 (1981)].
In another process, this compound is synthesized by a ligand displacement reaction between RuCl
3
and bis(ethylcyclopentadienyl)iron Fe(C
2
H
5
C
5
H
4
)
2
[G. J. Ganthier, Chem. Commun. 690 (1969)].
The bis(acetylcyclopentadienyl)ruthenium Ru(C
5
H
4
COCH
3
)
2
and bis(ethylcyclopentadienyl)iron Fe(C
2
H
5
C
5
Fattibene Arthur T.
Fattibene Paul A.
Fattibene & Fattibene
Kabushikikaisha Kojundokagaku Kenkyusho
Meeks Timothy
LandOfFree
Process for producing bis(alkyl-cyclopentadienyl) ruthenium... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for producing bis(alkyl-cyclopentadienyl) ruthenium..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for producing bis(alkyl-cyclopentadienyl) ruthenium... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2513300