Compositions – Electrically conductive or emissive compositions
Reexamination Certificate
1999-08-09
2001-04-10
Gupta, Yogendra (Department: 1755)
Compositions
Electrically conductive or emissive compositions
C252S512000, C252S513000, C156S247000, C174S256000, C174S257000, C427S123000, C427S096400
Reexamination Certificate
active
06214259
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dispersion containing Cu ultrafine particles individually dispersed therein and more particularly to a dispersion containing individually dispersed Cu ultrafine particles, which can be used for forming fine distributing wires of semiconductor substrates such as LSI substrates and for embedding or filling up recessed portions, such as via holes and contact holes, formed on the substrates.
2. Prior Art
As metal pastes for forming a conductive, uniform and fine pattern used when forming multilayer distributing wires on semiconductor substrates such as LSI substrates, there have conventionally been known those comprising an organic solvent containing alcohols or organic esters which have not less than 5 carbon atoms and ultrafine metal particles having a particle size of not more than 1000 Å (0.1 &mgr;m) uniformly dispersed therein while the surface of the ultrafine particles are individually surrounded by or covered with the organic solvent (see, for instance, Gazetted Japanese Patent No. 2,561,537).
However, these metal pastes according to the conventional techniques suffer from the following drawbacks. As the width of the distributing wires formed on an LSI substrate has increasingly been finer from 0.25 &mgr;m to 0.18 &mgr;m or even more finer, the metal paste applied onto the substrate begins to be dried prior to sufficient embedding or filling up of grooves for distributing wires or it is difficult to completely embed or fill up fine grooves with the metal paste because the paste has a too high viscosity.
SUMMARY OF THE INVENTION
The present invention has been developed in order to solve these problems associated with the conventional techniques and accordingly, it is an object of the present invention to provide a dispersion containing Cu ultrafine particles individually dispersed therein, which can completely embed or fill up recessed portions, such as fine grooves for distributing wires, via holes and contact holes, formed on semiconductor substrates such as LSI substrates and which permits the formation of a conductive, uniform and fine pattern on the substrate.
According to the present invention, the foregoing object can effectively be accomplished by providing a dispersion containing Cu ultrafine particles individually dispersed therein (hereinafter simply referred to as “individual Cu ultrafine particle dispersion”), which has a viscosity of not higher than 50 cP (as determined at 20° C.), and which can be prepared by mixing an organic solvent that is hardly evaporated at room temperature, but can be evaporated during the drying-firing step upon forming Cu-distributing wires on a semiconductor substrate with metal Cu-containing ultrafine particles having a particle size of not greater than 0.01 &mgr;m, wherein the surface of the Cu individual ultrafine particles are surrounded by or covered with the organic solvent and thus these particles are independently dispersed in the solvent. The organic solvent is preferably those which can be evaporated at a temperature of not less than 150° C. Examples of the organic solvents preferably used herein are mineral spirits, tridecane, dodecylbenzene or mixture thereof or these solvents to which &agr;-terpineol is added. Moreover, these solvents may, if necessary, be mixed with a hydrocarbon such as Pinene or the like, an alcohol such as n-Heptanol or the like, an ether such as Ethyl benzyl ether or the like, an ester such as n-Butyl stearate or the like, a ketone such as Diisobutyl ketone or the like, an organic nitrogen atom-containing compound such as Triisopropanol amine or the like, or an organic silicon atom-containing compound such as Silicon oil or the like, which have not less than 5 carbon atoms, or a mixture thereof, depending on the purpose of the Cu— containing dispersion to be used. Examples of the foregoing metal Cu— containing ultrafine particles desirably used herein can be those comprising elemental Cu particles, CuO particles or mixed Cu and CuO particles. In addition, the concentration of the metal Cu-containing ultrafine particles in the dispersion in general ranges from 5 to 70% by weight and preferably 15 to 50% by weight on the basis of the total weight of the dispersion. If the concentration exceeds 70%, the viscosity becomes too high and if the concentration is below 15%, the film thickness is too small. The viscosity of the individual Cu ultrafine particle dispersion is not more than 50 cP and preferably not more than 10 cP at 20° C. This is because if the viscosity exceeds 50 cP, the resulting dispersion does not show the desired characteristic properties such as recessed portion (such as grooves for distributing wires, via holes and contact holes)-filling up properties. The metal Cu-containing ultrafine particles may comprise, in addition to elemental Cu, at least one metal or metal-containing compound whose solubility in Cu is low and which is susceptible to the reaction with the basic material for a semiconductor substrate and thus the adhesion thereof to the basic material may be substantially improved. Specific examples of such metals or metal-containing compounds other than elemental Cu are Mg, Al, B, Ta, Nb and V and compounds containing these metals. The compounds containing the above-mentioned includes, for instance, (C
17
H
35
COO)
2
Mg and the like. The amount of these metals or metal-containing compounds to be added to the metal Cu-containing ultrafine particles ranges from 0.5 to 5 wt % based on the total weight of the Cu ultrafine particles.
REFERENCES:
patent: 5587111 (1996-12-01), Watanabe et al.
patent: 5746868 (1998-05-01), Abe
patent: 5750194 (1998-05-01), Watanabe et al.
patent: 5953629 (1999-09-01), Imazeki et al.
patent: 4-210481 (1992-07-01), None
patent: 9-134891 (1997-05-01), None
T. Sawaguchi, et al., “Effect of Microstructure of Bismuth Metal Particle Filled Ceramic Composite on the PTCR Property,” Proceedings of the Annual Meeting, 1998, The Ceramic Society of Japan, Mar. 3, 1998, p. 319.
T. Sawaguchi, et al., “Effect of Resistivity of the Matrix Ceramics in Bismuth Metal Particle Filled Ceramic Composite on the PTCR Property,” Proceedings of the Fall Meeting, 1997, The Ceramic Society of Japan, Oct. 2, 1997, vol. 10, p. 197.
T. Sawaguchi, et al., “The PTCR Property of the Bismuth Metal Particle Filled Ceramic Composite Sintered by Hot Pressing,” Proceedings of the Fall Meeting, 1998, The Ceramic Society of Japan, Oct. 1, 1998, vol. 11, p. 106.
Imazeki Nobuya
Murakami Hirohiko
Oda Masaaki
Yamakawa Hiroyuki
Arent Fox Kintner & Plotkin & Kahn, PLLC
Gupta Yogendra
Hamlin Derrick G.
Vacuum Metallurgical Co., Ltd.
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