Abrasive tool making process – material – or composition – With inorganic material
Reexamination Certificate
2000-07-25
2003-03-04
Utech, Benjamin L. (Department: 1765)
Abrasive tool making process, material, or composition
With inorganic material
C438S693000, C051S308000, C051S309000
Reexamination Certificate
active
06527817
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a composition and method for planarizing or polishing a surface, such as the surface of a semiconductor or metal layer of a memory or rigid disk.
BACKGROUND OF THE INVENTION
Compositions for planarizing or polishing the surface of a substrate are well known in the art. Polishing slurries typically contain an abrasive material in an aqueous solution and are applied to a surface by contacting the surface with a polishing pad saturated with the slurry composition. Typical abrasive materials include silicon dioxide, cerium oxide, aluminum oxide, zirconium oxide, and tin oxide. U.S. Pat. No. 5,527,423, for example, describes a method for chemically-mechanically polishing a metal layer by contacting the surface with a polishing slurry comprising high purity fine metal oxide particles in an aqueous medium.
Conventional polishing compositions typically are not entirely satisfactory at planarizing semiconductor wafers. In particular, polishing slurries can have less than desirable polishing rates, and their use in chemically-mechanically polishing semiconductor surfaces can result in poor surface quality. Because the performance of a semiconductor wafer is directly associated with the planarity of its surface, it is crucial to use a polishing composition that has a high polishing efficiency, uniformity, and removal rate and leaves a high quality polish with minimal surface defects.
The difficulty in creating an effective polishing composition for semiconductor wafers stems from the complexity of the semiconductor wafer. Semiconductor wafers are typically composed of a substrate, on which a plurality of transistors has been formed. Integrated circuits are chemically and physically connected into a substrate by patterning regions in the substrate and layers on the substrate. To produce an operable semiconductor wafer and to maximize the yield, performance, and reliability of the wafer, it is desirable to polish select surfaces of the wafer without adversely affecting underlying structures or topography. In fact, various problems in semiconductor fabrication can occur if the process steps are not performed on wafer surfaces that are adequately planarized.
There have been many attempts to improve the polishing efficiency and uniformity of conventional polishing agents, while minimizing defectivity of the polished surface and damage to underlying structures or topography. For example, U.S. Pat. No. 5,340,370 describes a polishing composition comprising an abrasive, an oxidizing agent, and water, which purportedly yields an improved removal rate and polishing efficiency. Similarly, U.S. Pat. No. 5,622,525 describes a polishing composition comprising colloidal silica having an average particle size of 20-50 nm, a chemical activator, and demineralized water.
A need remains, however, for compositions and methods that will exhibit desirable planarization efficiency, uniformity, and removal rate during the polishing and planarization of substrates, while minimizing defectivity, such as surface imperfections and damage to underlying structures and topography during polishing and planarization. The present invention seeks to provide such a composition and method. These and other advantages of the present invention will be apparent from the description of the invention provided herein.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to a composition for planarizing or polishing a surface. The polishing composition of the present invention comprises (a) a liquid carrier, (b) a chemical accelerator, and (c) solids comprising about 5-90 wt. % of fumed metal oxide and about 10-95 wt. % of abrasive particles, wherein about 90% or more of the abrasive particles (i.e., by number) have a particle size no greater than 100 nm. The present invention also provides a method of planarizing or polishing a surface comprising contacting the surface with the composition of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention provides a composition comprising (a) a liquid carrier, (b) a chemical accelerator, and (c) solids comprising about 5-90 wt. % of fumed metal oxide and about 10-95 wt. % of abrasive particles, wherein about 90% or more of the abrasive particles (by number) have a particle size no greater than 100 nm. The composition is useful in planarizing or polishing a surface. The present invention allows for a high polishing efficiency, uniformity, and removal rate of a surface with minimal defectivity, such as field loss of underlying structures and topography.
The total solids can be present in any suitable concentration in the composition of the present invention. The solids desirably are present in a concentration of about 0.1 wt. % or more (e.g., about 0.1-40 wt. %). Preferably, the total solids concentration is about 0.1-30 wt. % (e.g., about 1-30 wt. %) of the composition.
The solids of the composition of the present invention comprise about 5-90 wt. % of fumed metal oxide and about 10-95 wt. % of abrasive particles (i.e., the abrasive particles are at least about 10 wt. % of the total solids). The solids of the composition desirably comprise about 10-85 wt. % (e.g., about 15-75 wt. %) of fumed metal oxide and about 15-90 wt. % (e.g., about 25-85 wt. %) of abrasive particles (i.e., the abrasive particles are at least about 15 wt. % (e.g., at least about 25 wt. %) of the total solids). Preferably, the solids comprise about 15-60 wt. % (e.g., about 20-50 wt. %) of fumed metal oxide and about 40-85 wt. % (e.g., about 50-80 wt. %) of abrasive particles (i.e., the abrasive particles are at least about 40 wt. % (e.g., at least about 50 wt. %) of the total solids).
The fumed metal oxide of the composition of the present invention can be any suitable fumed (pyrogenic) metal oxide. Suitable fumed metal oxides include, for example, fumed alumina, fumed silica, fumed titania, fumed ceria, fumed zirconia, fumed germania, and fumed magnesia, coformed products thereof, cofumed products thereof, and mixtures thereof. Preferably, the fumed metal oxide of the composition of the present invention is fumed silica.
Any suitable abrasive particles can be present in the composition of the present invention. Desirable abrasive particles are metal oxides. Suitable metal oxides include alumina, silica, titania, ceria, zirconia, and magnesia. Also suitable for use in the composition are abrasive particles prepared in accordance with U.S. Pat. No. 5,230,833 and various commercially available products, such as the Akzo-Nobel Bindzil 50/80 product and the Nalco 1050, 2327, and 2329 products, as well as other similar products available from DuPont, Bayer, Applied Research, Nissan Chemical, and Clariant. Preferably, the abrasive particles of the composition of the present invention are a condensation-polymerized metal oxide, e.g., condensation-polymerized silica. Condensation-polymerized silica typically is prepared by condensing Si(OH)
4
to form colloidal particles.
The abrasive particles of the composition of the present invention are such that about 90% or more of the abrasive particles (by number) have a particle size no greater than 100 nm. Preferably, the abrasive particles are such that at least about 95%, 98%, or even substantially all (or actually all) of the abrasive particles (by number) have a particle size no greater than 100 nm. These particle size preferences for the abrasive particles (i.e., whereby at least about 90%, 95%, 98%, substantially all, and all of the abrasive particles (by number) are no greater than a specific size of abrasive particle) also can pertain to other particle sizes, such as 95 nm, 90 nm, 85 nm, 80 nm, 75 nm, 70 nm, and 65 nm.
Similarly, the abrasive particles of the composition of the present invention can be such that at least about 90%, 95%, 98%, or even substantially all (or actually all) of the abrasive particles (by number) have a particle size no less than 5 nm. These particle size preferences for the abrasive particles (i.e., whereby at least about 90%, 95%, 98%, subst
Dirksen James A.
Fang Mingming
Mueller Brian L.
Cabot Microelectronics Corporation
Deo Duy-Vu
Utech Benjamin L.
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