Compositions – Etching or brightening compositions
Reexamination Certificate
2001-07-03
2003-05-20
Moore, Margaret G. (Department: 1712)
Compositions
Etching or brightening compositions
C252S079400, C252S079300, C106S003000, C216S089000, C438S693000, C451S036000
Reexamination Certificate
active
06565767
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to polymer particles obtained by polycondensation of at least one from among Compound 1 represented by the following general formula (1): [M(OR
1
)
z
], hydrolysates of Compound 1 and partial condensates of Compound 1 (hereafter also collectively referred to as “Compound 1 and the like”) and at least one from among Compound 2 represented by the following general formula (2): [(R
2
)
n
M(OR
3
)
z-n
], hydrolysates of Compound 2 and partial condensates of Compound 2 (hereafter also collectively referred to as “Compound 2 and the like”). The present invention further relates to a polishing material (particularly chemical Mechanical polishing slurry (CMP slurry)) containing an aqueous dispersion prepared by dispersing the polymer particles in water.
For chemical Mechanical polishing (CMP) of semiconductor wafers and the like, the abrasive used have conventionally been aqueous dispersions of high-purity inorganic particles such as silica or alumina, synthesized mainly by gas phase reaction methods. However, inorganic particles synthesized by gas phase reaction methods exhibit severe secondary aggregation, and when preparing the aqueous dispersion it is necessary to fracture and fragment the aggregates in the water. Insufficient fracturing and fragmentation of the aggregates creates a problem in that the aqueous dispersion will become more viscous or gelled with time thus losing its fluidity, or the aggregates will separate and precipitate, rending the dispersion unusable as a polishing material.
Many different apparatuses have been proposed for dispersion of aggregates of inorganic particles synthesized by gas phase reaction methods. The use of such apparatuses, however, results in the problem of contamination of metals and other impurities. Another problem is that fracturing and fragmentation of the aggregates cannot be adequately achieved, and coarse particles 5 &mgr;m or greater in size remain that raise the viscosity and cause gelation or sedimentation. These coarse particles also create scratches on the surfaces of polishing wafer, such as wafers, during the polishing step of chemical mechanical polishing or the like, and sometimes the inorganic particles remain on the surfaces of the wafers, and the like, after washing.
Methods for synthesis of particulate silica in solutions are also known. In JOURNAL OF COLLOID AND INTERFACE SCIENCE 26, 62-69 (1968) there is described a method of synthesizing nearly spherical-shaped high-purity silica with a mean particle size of 50-2000 nm in an alkaline aqueous solution, using tetraethoxysilane as the starting material in the presence of an alcohol. Using this silica as abrasive for chemical mechanical polishing has the advantage of minimal scratching, such as taught on page 142 of CMP SCIENCE (Science Forum Publications, 1997). However, it has a problem in that the polishing rate is low and the abrasive tend to remain in the surface of polishing wafer and the like after washing.
The reason for the low polishing rate is that the particles are nearly spherical and too hard, and the abrasives therefore roll on the surface of polishing wafer, failing to adequately function as a polishing material, particularly a CMP slurry. Particularly when the polishing wafer is a ductile metal such that numerous abrasives remain on the surface of polishing wafer after washing, the particles that are nearly spherical and hard become buried in the polishing wafer surface.
It has been conventional to use polymer particles with a narrow particle size distribution obtained by copolymerizing vinyl monomers, and the like., for such uses as standard particles, diagnostic agent carrier particles, lubricants and the like. However, such polymer particles do not always have sufficient hardness and heat resistance, and when used as standard particles or lubricants, application of excess shear stress or exposure to high temperature can cause deformation or destruction of the particles, and therefore their uses are limited. In order to deal with these problems there have been proposed particles made of copolymers of crosslinkable vinyl monomers, and the like., that are copolymerized with a high degree of crosslinking. However, particles made of such crosslinked polymers have lower hardness and insufficient heat resistance compared to inorganic-based particles, and therefore are not suitable for a very wide field of uses.
For uses such as electronic materials, magnetic materials, heat-resistant materials, and the like, there have been employed particles made of numerous metal compounds, and a variety of composite particles have been proposed for diverse purposes. As such types of composite particles there may be mentioned composite particles comprising iron oxide particles coated with silicon compounds, so that in production of needle-shaped magnetic material by heat treatment, shape collapsing and sintering between magnetic material is prevented; composite particles comprising iron powder coated with copper as a high strength material for powder metallurgy; and composite particles comprising iron oxide particles coated with antimony oxide and aluminum oxide for improved heat resistance. However, aqueous dispersions containing these composite particles have a problem in terms of shelf life, and since they all are composed of metal compounds, they are too hard and are not always adequately suited for diverse purposes. The development of polymer particles with appropriate hardness has thus become a necessity particularly in the fields of electronic materials, magnetic materials, optical materials and so forth.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide polymer particles with sufficient strength and hardness, having excellent heat resistance and appropriate flexibility, that are useful as a polishing material, particularly a CMP slurry, and the like. It is another object of the invention to provide a CMP slurry that is useful for chemical mechanical polishing particularly of semiconductor wafers, magnetic disks and the like, that allows a high polishing rate with few scratches, and that leaves little residue on the surface of polishing wafer. It is yet another object of the invention to provide a polymerization technique whereby polymer particles that can only be made as small as about 50 nm at most according to the prior art, can be made as small as 3 nm.
The polymer particles according to a first aspect of the present invention are characterized by being obtained by polycondensation of at least one from among Compound 1 represented by general formula (1) below, hydrolysates of Compound 1 and partial condensates of Compound 1, and at least one from among Compound 2 represented by general formula (2) below, hydrolysates of Compound 2 and partial condensates of Compound 2, and by having a mean particle size of 3-1000 nm.
M(OR
1
)
z
(1)
(R
2
)
n
M(OR
3
)
z-n
(2)
(In general formula (1) and general formula (2), M is Al, Si, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Zr, Nb, Mo, Sn, Sb, Ta, W, Pb or Ce, and z is the atomic valence of M. R
1
in general formula (1) and R
3
in general formula (2) are each an alkyl group of 1-5 carbon atoms, an acyl group of 1-6 carbon atoms or an aryl group of 1-9 carbon atoms. R
2
in general formula (2) is a monovalent organic group of 1-8 carbon atoms and n is an integer of from 1 to (z−2). R
1
, R
2
and R
3
may be the same or different.)
The polymer particles according to a second aspect of the present invention are characterized by being obtained by polycondensation of at least one from among Compound 1 represented by general formula (1) in claim 1, hydrolysates of Compound 1 and partial condensates of Compound 1, in the presence of polymer particles according to the first invention, and by having a mean particle size of 3-1000 nm.
The polymer particles according to the second aspect of the present invention are characterized by being obtained by polycondensation of at least one from among Compound 1
Hattori Masayuki
Iio Akira
Motonari Masayuki
JSR Corporation
Moore Margaret G.
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