Organic compounds -- part of the class 532-570 series – Organic compounds – Heavy metal containing
Reexamination Certificate
2000-12-15
2001-10-30
Shaver, Paul F. (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heavy metal containing
C556S011000, C428S457000, C427S250000, C427S252000, C106S001050, C106S001230, C106S001260
Reexamination Certificate
active
06310228
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to organic copper compounds for making copper (Cu) thin-films used in wiring of semiconductor devices by a metal organic chemical vapor deposition (hereinafter referred to as MOCVD) process, to liquid mixtures (solutions) containing the compounds, and to copper thin-films prepared by the MOCVD process using the solutions.
2. Description of the Related Art
As an organic copper compound used in a MOCVD process, copper complex Cu(I) tmvs·hfac (wherein tmvs represents trimethylvinylsilane and hfac represents hexafluoroacetylacetonate), which satisfies a combination of strict chemical, structural, and electrical requirements over a relatively wide range, has selective deposition ability, and is liquid at room temperature, is well known in Japanese Unexamined Patent Application Publication No. 5-202,476. This compound, however, is extremely unstable, and is readily decomposed at room temperature to precipitate metallic copper and to form copper(II)(hfac)
2
as a by-product. Thus, the organic copper compound cannot be uniformly supplied during a film deposition process, resulting in less reproducible film deposition.
In order to solve this problem, copper(I) atms·hfac (wherein atms represents allyltrimethylsilane), which exhibits a more stable vaporization rate than that of copper(I) tmvs·hfac, high volatility, and high thermal stability, and is liquid at room temperature, is disclosed in Japanese Unexamined Patent Application Publication Nos. 7-252266 and 10-131514.
On the other hand, a copper precursor compound is disclosed in Japanese Unexamined Patent Application Publication No. 10-195654. This compound contains copper(I) hfac and methoxymethylsilylolefin ligand. When the compound is heated to a vaporization temperature, the electron donor ability of oxygen in the methoxymethylsilylolefin ligand provides a stable bond between the copper and the methoxymethylsilylolefin ligand. In this copper precursor compound, the oxygen atom of the methoxy group primarily suppresses the volatility of the copper precursor compound. Thus, the copper precursor compound exhibits improved thernal stability and a prolonged life.
Both copper(I) atms·hfac disclosed in Japanese Unexamined Patent Application Publication Nos. 7-252266 and 10-135154 and the copper precursor compound disclosed in Japanese Unexamined Patent Application Publication No. 195654, as well as copper(I) tmvs·hfac, exhibit low film deposition rate and poor adhesiveness to underlayers compared to physical deposition processes, such as a sputtering process.
SUMMARY OF THE INVENTION
The present invention provides a copper based organic compound which can exhibit a high film deposition rate, can effectively decompose on a substrate, is highly volatile, and exhibits high adhesiveness to an underlayer. The present invention also provides a liquid mixture containing this compound. The organic compound barely decomposes during storage and has a prolonged life. The organic compound can be used to form a high-purity copper thin film that firmly adheres to an underlayer.
A first aspect of the present invention relates to an organic copper compound represented by the following formula (1) in which monovalent copper is coordinated with a &bgr;-diketone compound and an unsaturated hydrocarbon compound having a silyloxy group:
In the formula, R is an unsaturated hydrocarbon moiety, L is the &bgr;-diketone compound, X
1
, X
2
, and X
3
are each a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 4 carbon atoms, and X
1
, X
2
, and X
3
may be the same or different from each other.
The organic copper compound according to the first aspect has an oxosilane group in which a silicon atom having electron donor ability is directly bonded to an oxygen atom having higher electron donor ability. By using the oxosilane group as a ligand, the &pgr; bonding of the copper atom is enhanced, and the chemical stability of the copper compound is improved.
A second aspect of the present invention relates to an organic copper compound represented by the following formula (2) in which monovalent copper is coordinated with hexafluoroacetylacetone and an olefinic hydrocarbon compound with 3 or more carbon atoms having a silyloxy group bonded to one or two alkoxy groups. In this organic copper compound, monovalent copper is coordinated with hexafluoroacetylacetone as the &bgr;-diketone compound and the unsaturated hydrocarbon compound having the silyloxy group.
In the formula, R′ is an olefinic hydrocarbon moiety with 3 or more carbon atoms, L′ is the hexafluoroacetylacetone, one or two of X
4
, X
5
, and X
6
are each an alkoxy group having 1 to 8 carbon atoms, the others of X
4
, X
5
, and X
6
are each an alkyl group having 1 to 8 carbon atoms or a hydrogen atom, and the alkoxy groups or the alkyl groups may be the same or different from each other.
Preferably, the olefinic hydrocarbon moiety is propenyl, butenyl, or pentenyl.
In the organic copper compound according to the second aspect, a combination of the alkoxy group and the alkyl group yields electron donor ability over the alkoxy group and the olefin moiety. The organic copper compound represented by the formula (2) is barely decomposed in a stock solution and exhibits high stability. In the compound represented by the formula (2), the alkyl group and the alkoxy group results in high steric hindrance. Thus, the compound has a high film deposition rate, is effectively decomposed on a substrate, is highly volatile, and exhibits high adhesiveness to an underlayer.
A third aspect of the present invention relates to an organic copper compound represented by the following formula (3) in which monovalent copper is coordinated with hexafluoroacetylacetone and an olefinic hydrocarbon compound with 4 or more carbon atoms having a silyloxy group bonded to three alkoxy groups:
In the formula, R″ is an olefinic hydrocarbon moiety with 4 or more carbon atoms, L′ is the hexafluoroacetylacetone, Y
1
, Y
2
, and Y
3
are each an alkoxy group having 1 to 4 carbon atoms, and Y
1
, Y
2
, and Y
3
may be the same or different from each other.
Preferably, the olefinic hydrocarbon moiety is propenyl, butenyl, or pentenyl.
In the organic copper compound according to the second aspect, all the groups other than the olefinic hydrocarbon moiety bonded to the silicon atom are alkoxy groups. Thus, the electronic flow is further enhanced in view of molecular structure. Thus, copper readily approaches a substrate used in a deposition process, and the film deposition rate is increased.
A fourth aspect of the present invention relates to a liquid mixture comprising the organic copper compound according to any one of the first to third aspect and at least one liquid compound selected from the group consisting of trimethylvinylsilane, vinyloxytrimethylsilane, allyloxytrimethylsilane, allyltrimethylsilane, 3-hexyne, 2-butyne, and a Cu(I) hexafluoroacetylacetonate compound coordinated therewith.
This liquid mixture exhibits a higher deposition rate in a MOCVD process compared to that of a solution not containing the liquid compound.
A fifth aspect of the present invention relates to a liquid mixture comprising the organic copper compound according to any one of the first to third aspect and at least one liquid compound selected from the group consisting of copper(I) allyltrimethylsilane hexafluoroacetylacetonate (hereinafter referred to as copper(I) atms·hfac) represented by the following formula (4), copper(I) trimethylvinylsilane hexafluoroacetylacetonate (hereinafter referred to as copper(I) tmvs·hfac) represented by the following formula (5), and copper(I) trimethoxyvinylsilane hexafluoroacetylacetonate (hereinafter referred to as copper(I) tmovs·hfac) represented by the following formula (6).
In the fifth aspect of the present invention, the organic copper compound according to one of the first to third aspects is mixed with the above liquid compound, and a copper thin film is formed using th
Itsuki Atsushi
Ogi Katsumi
Mitsubishi Materials Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Shaver Paul F.
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