HK1050377B - Composition and method for planarizing surfaces - Google Patents

Description

Composition and method for planarizing surfaces

Field of the invention

The present invention relates to compositions and methods for planarizing or polishing a surface, such as the surface of a metal layer of a semiconductor or memory or optical disk.

Background

Compositions for planarizing or polishing the surface of a substrate are well known in the art. The polishing slurry is typically an abrasive material in an aqueous solution and is applied to the surface by contacting the surface with a polishing pad saturated with the slurry composition. Typical abrasive materials include silica, cesium oxide, alumina, zirconia, 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 an aqueous medium comprising high purity silicon metal oxide particles.

Conventional polishing compositions are not entirely satisfactory at polishing semiconductor wafers. In particular, polishing slurries have lower than desired polishing rates and can result in poor surface quality when used in the chemical mechanical polishing of semiconductor surfaces. Since the performance of semiconductor silicon wafers is related to surface flatness, it is important to use polishing compositions that have high polishing efficiency, uniformity, and removal rate, and leave a high quality polish with minimal surface defects.

Difficulties in effective polishing compositions for the manufacture of semiconductor wafers arise from the complexity of the semiconductor wafers. Semiconductor silicon wafers are typically composed of a substrate on which a number of transistors are formed. The entire circuit is chemically and physically connected to the substrate through the patterned areas in the substrate and layers on the substrate. In order to make available semiconductor wafers and to maximize yield, performance, and reliability of the wafers, it is desirable to polish select surfaces of the wafers without adversely affecting underlying structures or features. In fact, semiconductor fabrication can create a number of problems if the fabrication steps are not performed on a suitably planar silicon wafer surface.

Many improvements in polishing efficiency and uniformity have been attempted with conventional polishing agents, while attempts have been made to minimize defects in the polished surface, and damage to underlying structures or features. For example, U.S. Pat. No. 5,340,370 describes polishing compositions comprising a nuclear consumable, an oxidizing agent, and water, which are said to result in improved removal rates and polishing efficiencies. Similarly, U.S. Pat. No. 5,622,525 describes a polishing composition comprising colloidal silica having an average particle size of 20 to 50 nm, a chemical activator, and demineralized water.

However, there remains a need for compositions and methods that exhibit desirable planarization efficiency, uniformity, and removal rate while minimizing defectivity, such as surface imperfections, and damage to underlying structures and features during polishing and planarization of substrates. The present invention contemplates providing such compositions and methods. These and other advantages of the invention will be apparent from the description of the invention herein.

Summary of The Invention

The present invention is directed to a composition for planarizing or polishing a surface. The polishing composition of the invention comprises (a) a liquid carrier, (b) a chemical accelerator, and (c) a solid comprising about 5 to 90 wt.% of fumed metal oxide and about 10 to 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 invention also provides a method comprising contacting a surface with a composition of the invention to planarize or polish the surface.

Description of the preferred embodiments

The present invention provides a composition comprising (a) a liquid carrier, (b) a chemical accelerator, and (c) a solid comprising about 5 to 90 wt% fumed metal oxide and about 10 to 95 wt% 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 for the planarization or polishing of surfaces. The invention provides high polishing efficiency, uniformity and removal rate of the surface, and minimizes field loss with defectivity such as underlying structure and topography.

All solids may be present in the compositions of the present invention at any suitable concentration. The concentration of solids desired is about 0.1 wt% or higher (e.g., about 0.1 to 40 wt%). Preferably, the total solids concentration is about 0.1 to 30 wt% (e.g., about 1 to 30 wt%) of the composition.

The solids of the composition of the present invention comprise about 5 to 90 weight percent fumed metal oxide and about 10 to 95 weight percent abrasive particles (i.e., at least about 10 weight percent of the total solids are abrasive particles). The solids of the composition preferably comprise about 10 to 85 wt% (e.g., about 15 to 75 wt%) fumed metal oxide and about 15 to 90 wt% (e.g., about 25 to 85 wt%) abrasive particles (i.e., at least about 15 wt% (e.g., at least about 25 wt%) of the total solids are abrasive particles). Preferably, the solids comprise about 15 to 60 wt% (e.g., about 20 to 50 wt%) fumed metal oxide and about 40 to 85 wt% (e.g., about 50 to 80 wt%) abrasive particles (e.g., at least about 40 wt% (e.g., at least about 50 wt%) of the total solids are abrasive particles).

The fumed metal oxide of the compositions of the invention can be any suitable fumed (pyrogenic) metal oxide. Suitable fumed metal oxides include, for example, fumed alumina, fumed silica, fumed titanium oxide, fumed cerium oxide, fumed zirconia, fumed germanium oxide, and fumed magnesium oxide and co-formed products thereof, co-fumed products thereof, and mixtures thereof. The fumed metal oxide of the composition of the invention is preferably fumed silica.

Any suitable abrasive particles may be included in the compositions of the present invention. The abrasive particles required are metal oxides. Suitable metal oxides include alumina, silica, titania, ceria, zirconia and magnesia. Also suitable in the compositions are abrasive particles prepared according to 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, and similar products available from DuPont, Bayer, Applied Research, Nissan chemical, and Clariant. The abrasive product of the composition of the present invention is preferably a condensation polymerized metal oxide, such as condensation polymerized silica. The condensation-polymerized silica is generally prepared by reacting Si (OH)₄Condensing to form colloid particles.

The abrasive particles of the compositions of the present invention are about 90% or more of the abrasive particles (by number) having a particle size no greater than 100 nm. Preferably, the abrasive particles have a particle size of no more than 100 nanometers, preferably at least about 95%, 98%, or substantially all (or virtually all) of the abrasive particles (by number). The abrasive particles have a particle size (i.e., at least about 90%, 95%, 98%, and substantially all of the abrasive particles do not exceed a particular size of the abrasive particles), and more preferably other particle sizes, such as 95 nm, 90 nm, 85 nm, 80nm, 75 nm, 70 nm, and 65 nm.

Likewise, the abrasive particles of the compositions of the present invention can have a particle size of at least about 90%, 95%, 98%, or substantially all (or substantially all) of the abrasive particles of no less than 5 nm. The abrasive particles have a particle size (i.e., at least about 90%, 95%, 98%, and substantially all of the abrasive particles are not smaller than the particular size of the abrasive particles), and more preferably, other particle sizes, such as 7 nm, 10 nm, 15 nm, 25 nm, and 30 nm.

The abrasive particles of the compositions of the present invention have a substantially bimodal particle size distribution in which about 30 to 70 percent (e.g., about 50 percent) of the abrasive particles have a particle size of about 30 to 50 nanometers, and about 30 to 70 percent (e.g., about 50 percent) of the abrasive particles have a particle size of about 70 to 90 nanometers. Preferably, the abrasive particles have a particle size distribution that is substantially bimodal, with about 30-70% (e.g., about 50%) of the abrasive particles having a particle size (by number) of about 35-45 nm, and about 30-70% (e.g., about 50%) of the abrasive particles having a particle size (by number) of about 75-85 nm.

The percentages used herein to describe the nature of the abrasive particles in terms of particle size are percentages by number other than weight, unless otherwise indicated. The particle size of the abrasive particles refers to the diameter of the particles. The particle size values listed here are in particular those which are based on visual inspection by means of a Transmission Electron Microscope (TEM) of at least 200 particles, with a statistically significant number of samples from the abrasive particles.

The abrasive particles may have a particle size distribution with a geometric number standard deviation corresponding to sigma-g (sigma)_g) Showing its characteristics. This sigma. The value may be determined by (a) dividing the value of the diameter at which 84% of the abrasive particles (by number) do not exceed by (b) the value of the diameter at which 16% of the abrasive particles (by number) do not exceed (i.e., σ)_g＝d₈₄/d₁₆) And (4) obtaining. Sigma of monodisperse abrasive particles_gThe value is about 1. When the abrasive particles become polydisperse (i.e. contain particles of increasing size difference),σ of abrasive particles_gThe value increases to above 1. Sigma of the abrasive particles_gThe value is typically about 2.5 or less (e.g., about 2.3 or less). Sigma of the abrasive particles_gThe value is preferably at least about 1.1 (e.g., about 1.1-2.3 (e.g., 1.1-1.3)), and is preferably σ_gThe value is at least about 1.3 (such as about 1.5-2.3 or even about 1.8-2.3).

The compositions of the present invention may also be characterized by bulk density. The bulk density is 1 minus the settled volume of all the composition ingredients mixed together divided by the sum of the individual settled volumes of the individual composition ingredients. Thus, the bulk density (PD) is 1- (V)_{Sum of}/(V_fmo+V_ap) Wherein V) is_fmoIs the volume of fuming metal oxide (abrasive particles are not present), V_apIs the volume of the abrasive particles (fuming metal oxide is not present) and the sum of V is the volume of fuming metal oxide mixed with the abrasive particles. The volume of these individual fumed metal oxides, the volume of the individual abrasive particles, and the mixed volume of the two materials in a mixed state are measured by continuously centrifuging the sample under any suitable gravitational force for a measurable volume period equal to 1.2 stokes settling time for the smallest particles in the material.

Desirably, the composition has a bulk density value of at least about 0.1, preferably a bulk density value of at least about 0.15. More particularly, the bulk density value of the composition is at least about 0.2. Particularly preferably, the compositions of the present invention have a bulk density value of at least about 0.3 (e.g., about 0.3-0.6) or even at least about 0.4 (e.g., about 0.4-0.6 or about 0.5-0.6). Bulk density values of the compositions of the present invention are generally about 0.7 or less (such as about 0.65 or less, or even about 0.6 or less).

Any suitable chemical accelerator may be included in the compositions of the present invention. Chemical accelerators can be used to improve the planarization or polishing of a substrate, as evidenced, for example, by increasing the rate of removal of the substrate.

Suitable chemical accelerators may include: such as oxidizing agents, chelating or complexing agents, catalysts, and the like. Suitable oxidizing agents can include, for example, oxidized halides (e.g., chlorates, bromates, iodates, perchlorates, perbromates, periodates, mixtures thereof, and the like). Suitable oxidizing agents also include, for example, perboric acid, perborate salts, percarbonates, nitrates, persulfates, peroxides, peroxyacids (e.g., peracetic acid, perbenzoic acid, m-chloroperbenzoic acid, salts thereof, mixtures thereof, and the like), permanganates, chromates, cerium compounds, ferricyanides (e.g., potassium ferricyanide), oxidized metal salts (e.g., sodium salts, iron salts, potassium salts, aluminum salts, and the like), oxidized metal complexes, non-metal oxidized acids, ammonium salts, phosphonium salts, trioxides (e.g., vanadium trioxide), mixtures thereof, and the like.

Suitable chelating or complexing agents can include, for example, carbonyl compounds (e.g., acetylacetonates, and the like), simple carboxylates (e.g., acetates, aryl carboxylates, and the like), carboxylates containing one or more hydroxyl groups (e.g., glycolates, lactates, gluconates, gallic acid and salts thereof, and the like), di-, tri-, and polycarboxylates (e.g., oxalates, phthalates, citrates, succinates, tartrates, malates, edetates (e.g., disodium EDTA), mixtures thereof, and the like), carboxylates containing one or more sulfonic and/or phosphonic groups, and the like. Suitable chelating or complexing agents can also include, for example, di-or tri-or polyols (e.g., ethylene glycol, pyrocatechol, pyrogallol, tannic acid, and the like), halides (e.g., fluorides, chlorides, bromides, and iodides, and the like), and the like. Suitable chemical accelerators may also include, for example, sulfur-containing compounds such as thiols, thioesters, thioethers, and sulfates, and nitrogen-containing compounds such as amines, imines, amides, and imides. Suitable nitrogen-containing compounds include, for example, primary amines, secondary amines, tertiary amines, quaternary amines, etheramines, hydroxylated amines, amino alcohols, aminoetheralcohols, amino acids (e.g., glycine, alanine, iminodiacetic acid, valine, leucine, isoleucine, serine, and/or threonine), oligomeric amines, oligomeric imines, oligomeric amides, oligomeric imides, polymeric amines, polymeric imines, polymeric amides, polymeric imides, and mixtures thereof.

Furthermore, suitable chemical accelerators may comprise, for example, phosphate ions (e.g. PO structure)₄The constructs herein include double bonds (P ═ O)), phosphonate ions (e.g., the chemical construct RO-PO), and the like₃Or R₂O₂-PO₂Wherein the structure includes a double bond (P ═ O)), and wherein R is an organic moiety selected from the group consisting of alkyl moieties, aryl moieties, cyclic moieties, aromatic moieties, and heteroatom-containing organic moieties (e.g., N-containing organic moieties)), or combinations thereof. The phosphate ions may be derived from any suitable source of phosphate ions. Suitable phosphate ion sources include, for example, phosphoric acid and water-soluble phosphates, such as orthophosphates, polyphosphates and mixtures thereof. The source of phosphate ions may also be selected from the group consisting of pyrophosphates, tripolyphosphates, and mixtures thereof. Preferably, the source of phosphate ions is selected from the group consisting of sodium phosphate, potassium phosphate, lithium phosphate, cesium phosphate, magnesium phosphate, ammonium phosphate, phosphoric acid, and the like, and mixtures thereof. The phosphonate ions can be derived from any suitable source of phosphonate ions. Suitable phosphonate ion sources include, for example, amine-containing phosphonates, imine-containing phosphonates, amide-containing phosphonates, nitrogen-free phosphonate compounds (e.g., amine-free phosphonate compounds), and mixtures thereof. Preferably, the phosphonate ion source is selected from the group consisting of acetyl phosphate, 2-aminoethyl dihydrogen phosphate, aminotri- (methylene phosphate), nitrilotris (methylene) triphosphonic acid, 1-hydroxyethylidene-1-diphosphonic acid, and diethylene triamine penta- (methylene phosphonic acid), and mixtures thereof.

It will be appreciated that many of the above-described compounds may exist in the form of salts (e.g., metal salts, ammonium salts, etc.), acids, or partial salts. For example, citrates include citric acid and mono-, di-, and tri-salts thereof; phthalates include phthalic acid and its mono-salts (e.g., potassium hydrogen phthalate) and its di-salts; perchloric acid comprises the corresponding acid (i.e., perchloric acid) and salts thereof.

Furthermore, more than one function of a particular compound may be used. For example, certain compounds may have both oxidizing and chelating agent functions (e.g., ammonium persulfate, hydroxylamine nitrate, etc.). In addition, the compositions of the present invention may include two or more chemical accelerators, for example three or more chemical accelerators, or even four or more chemical accelerators. In this respect, the chemical accelerators function to bring about an enhancement or synergistic effect. For example, the compositions of the present invention may include an oxidizing agent and a complexing agent. Thus, the compositions of the present invention preferably comprise an oxidizing agent and an amino acid, such as glycine, alanine, iminodiacetic acid, valine, leucine, isoleucine, serine and/or threonine. Similarly, the composition may include an oxidizing agent and a phosphate-containing compound, or may include an oxidizing agent and a carboxylate compound. Thus, the composition of the present invention preferably comprises hydrogen peroxide and glycine.

Any suitable amount of chemical accelerator may be included in the compositions of the present invention. The amount of chemical accelerator required in the polishing composition is about 0.01 to 20 wt.% (i.e., about 0.01 to 15 wt.%). Preferably, the chemical accelerator is present in the compositions of the present invention in an amount of about 0.1 to about 10 weight percent. More preferably, the chemical accelerator is present in the composition in an amount of about 0.1 to about 5 wt.% (i.e., about 0.1 to about 2 wt.%).

The compositions of the present invention may further comprise one or more additional ingredients such as surfactants, polymeric stabilizers or other surface active dispersants, pH adjusters, regulators or buffers, and the like. Suitable surfactants can include, for example, cationic surfactants, anionic surfactants, nonionic surfactants, amphoteric surfactants, fluorinated surfactants, mixtures thereof, and the like. Suitable polymeric stabilizers or other surface-active dispersants may include, for example, phosphoric acid, organic acids, tin oxide, organic phosphonates, mixtures thereof, and the like. Suitable pH adjusters, regulators, or buffers can include, for example, sodium hydroxide, sodium carbonate, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, citric acid, potassium phosphate, mixtures thereof, and the like.

Any suitable carrier (e.g., solvent) may be used in the compositions of the present invention. The support is used to assist in the application of the fumed metal oxide and abrasive particles to the surface of a suitable substrate. The preferred carrier is water.

The pH of the compositions of the present invention is maintained within a range suitable for the end use. The composition desirably has a pH of about 2 to about 12. The preferred pH will depend on the particular chemical accelerator. For example, when the chemical accelerator is ammonium persulfate and NH 3, the pH is preferably 9 to 11. When the chemical accelerator is iron (III) nitrate, the pH is preferably 2.5 or less, more preferably about 2. When the chemical accelerator is hydroxylamine nitrate, the pH is preferably about 2 to 5.

The invention also provides a method for planarizing or polishing a surface. The method comprises contacting a surface with a composition described herein. The surface may be treated with the composition by any suitable technique. For example, the composition can be applied to the surface via the use of a polishing pad.

The method of the present invention can planarize or polish the substrate at relatively high speeds, such as removing a silicon dioxide layer from a laminated substrate at relatively high speeds. Furthermore, the compositions of the present invention are well suited for the planarization or polishing of a variety of hard workpieces such as memory or rigid disks, metals (e.g., noble metals), ILD layers, semiconductors, micro-electro-mechanical systems, ferroelectrics, magnetic heads, polymer films, and low and high dielectric constant films. The composition can also be used in the manufacture of integrated circuits and semiconductors. The compositions of the present invention exhibit desirable planarization efficiency, uniformity, removal rate, and low defectivity during substrate planarization or polishing.

Examples

The following examples further illustrate the invention but, of course, should not be construed as in any way limiting its scope.

The memory or hard disk (see one of the following embodiments (i.e., embodiment 5)) is a memory or hard disk available from seagatete technology. The memory or hard disk is a disk coated (electroplated) with nickel-phosphorus on an aluminum substrate. The memories or hard disks are pre-polished before being used in the following embodiments, and the surface roughness of each memory or hard disk is 30 to 50 angstroms.

Both the memory and the hard disk were polished using a desktop polisher manufactured by Streuers (West Lake, Ohio). The desktop polisher used a Rotopol 31 base and a Rotoforce 3 down force unit. The polishing pad used in the following examples was a 30.48 centimeter (12 inch) diameter PolytexHi pad manufactured by Rodel. The memory or hard disk was polished using a face speed of 150rpm, a polishing carrier speed of 150rpm, and a slurry flow rate of 100 ml/min for 10 minutes on each side, but the memory or hard disk in example 6 was polished for 5 minutes. The polishing force used in all examples was 50N.

The nickel-phosphorus removal rate in each of the following examples was calculated by weighing a clean, dry memory or hard disk prior to polishing followed by polishing. The weight reduction was converted to a reduction in the thickness of the memory or hard disk using a nickel-phosphorus density of 8.05 grams per cubic centimeter.

Example 1

This example illustrates the combination and ratio of fumed metal oxide to abrasive particles in the composition of the invention and the importance of the presence of a chemical accelerator in maximizing the surface removal rate during surface planarization or polishing.

Nickel-phosphorus plated memory or hard disks are made using ten total solid concentrations including fumed silica (i.e., 0 wt.%, 25 wt.%, 50 wt.%, 75 wt.%, and 100 wt.%), condensation polymerized silica (i.e., 100 wt.%, 75 wt.%, 50 wt.%, 25 wt.%, and 0 wt.%) (measured as having an average particle size of about 20nm, σ%_g2.26), and hydroxylamine nitrate (HAN) (i.e., 0 wt.% HAN or 0.25 wt.% HAN) were polished separately. The pH of all compositions was about 3.5. The fumed silica is Cab-0-Sperse^RSC-E fumed silica in the form of an aqueous dispersion (Cabot corporation) was added to the composition. The condensation-polymerized silica is Bindzil R50/80 (Akzo-Nobel), wherein 90% or more by number of its particles have a particle size no greater than 100 nm, and about 90% or more by number of its particles have a particle size no less than about 5 nm. After using the polishing compositions, the removal rates for each composition were determined and the data obtained are set forth in Table 1 below.

TABLE 1

Composition comprising a metal oxide and a metal oxide	Relative weight percent fumed silica	Relative weight percent of condensed silica	Removal rate (microinches per minute) [ angstroms/minute ]]
					non-HAN	0.25Wt.％HAN
			1A	0			100	2.10[534]	2.70[686]
1B	25	75			2.28[579]	3.40[864]
			1C	50			50	2.28[579]	3.89[988]
1D	75	25			2.10[534]	5.70[1448]
			1E	100			0	1.41[358]	1.70[216]

It is evident from the data set forth in table 1 that the HAN-containing compositions exhibit removal rates that are significantly better than the removal rates of the HAN-free compositions. Further, the removal rate of the composition having HAN and containing about 25 to 75% fumed silica and 25 to 75% solid of condensation polymerized silica (compositions 1B, 1C and 1D) was superior to the removal rate of the composition having HAN and containing 100% fumed silica or 100% solid of condensation polymerized silica (compositions 1A and 1E). These results demonstrate the importance of the combination of the chemical accelerator and the mixture of fumed metal oxide and abrasive particles having the particle size characteristics described herein, and the fumed metal oxide to abrasive particle ratio, on the removal rate achieved by the compositions of the invention.

Example 2

This example illustrates the combination and ratio of fumed metal oxide to abrasive particles in the composition of the invention, and the importance of the presence of a chemical accelerator to maximize surface removal rate during surface planarization or polishing.

Nickel-phosphorus electroplated memoryOr hard disks, using ten total solid concentrations including fumed silica (i.e., 0 wt.%, 25 wt.%, 50 wt.%, 75 wt.%, and 100 wt.%), condensation polymerized silica (i.e., 100 wt.%, 75 wt.%, 50 wt.%, 25 wt.%, and 0 wt.%) (measured as having an average particle size of about 20 nanometers, σ ″)_g2.26), and Ammonium Persulfate (APS) and NH₃(i.e., 0.25 wt.% APS and 0.25 wt.% NH)₃Or 0 wt% APS and 0 wt% NH₃) Are polished separately. The fumed silica is Cab-O-Sperse^RSC-E fumed silica in the form of an aqueous dispersion (Cabot corporation) was added to the composition. The condensation-polymerized silica is Bindzil R50/80 (Akzo-Nobel), wherein 90% or more by number of its particles have a particle size no greater than 100 nm, and about 90% or more by number of its particles have a particle size no less than about 5 nm. After using the polishing compositions, the removal rates for each composition were determined and the data obtained are set forth in Table 2 below.

TABLE 2

Composition comprising a metal oxide and a metal oxide	Relative weight percent fumed silica	Relative weight percent of condensed silica	Removal rate (microinches per minute) [ angstroms/minute ]]
					APS-free and HAN-free	0.25Wt.％APS0.25Wt.％NH3
			2A	0			100	2.10[534]	2.80[711]
2B	25	75			2.28[579]	6.40[1626]
			2C	50			50	2.28[579]	4.60[1169]
2D	75	25			2.10[534]	3.20[813]
			2E	100			0	1.41[358]	0.85[216]

As is evident from the data set forth in Table 2, except for the composition containing 100 wt.% fumed silicaContaining APS and NH₃The compositions exhibit removal rates that are significantly better than those exhibited without APS and NH₃The removal rate of the composition of (1). In particular, it has ASP and NH₃And the solid compositions containing about 25-75% fumed silica and 25-75% condensation polymerized silica (compositions 2B, 2C, and 2D) had better removal rates than ASP and NH₃And the removal rate of compositions containing 100% fumed silica or 100% solids of condensation polymerized silica (compositions 2A and 2E). These results demonstrate the importance of combining the chemical accelerator with a mixture of fumed metal oxide and abrasive particles having the particle size characteristics described herein, and the proportion of fumed metal oxide to abrasive particles, at the removal rates achieved with the compositions of the invention.

Example 3

This example illustrates the combination and ratio of fumed metal oxide to abrasive particles in the composition of the invention, and the importance of the presence of a chemical accelerator to maximize surface removal rate during surface planarization or polishing.

Nickel-phosphorus plated memory or hard disks are made using ten total solid concentrations including fumed silica (i.e., 0 wt.%, 25 wt.%, 50 wt.%, 75 wt.%, and 100 wt.%), condensation polymerized silica (i.e., 100 wt.%, 75 wt.%, 50 wt.%, 25 wt.%, and 0 wt.%) (measured as having an average particle size of about 20nm, σ%_g2.26), and Fe (NO)₃)₃(i.e., 0 wt.% Fe (NO)₃)₃Or 0.25 wt.% Fe (NO)₃)₃) Are polished separately. All compositions had a pH of about 2. The fumed silica is Cab-O-Sperse^RSC-E fumed silica in the form of an aqueous dispersion (Cabot corporation) was added to the composition. The condensation-polymerized silica is Bindzil R50/80 (Akzo-Nobel), wherein 90% or more by number of its particles have a particle size no greater than 100 nm, and about 90% or more by number of its particles have a particle size no less than about 5 nm. After using the polishing compositions, the removal rates for each composition were determined and the data obtained are set forth in Table 3 below.

TABLE 3

Composition comprising a metal oxide and a metal oxide	Relative weight percent fumed silica	Relative weight percent of condensed silica	Removal rate [ Angstrom/min ]]
					Fe-free (NO)3)3	0.25Wt.％Fe(NO3)3
			3A	0			100	534	1653
3B	25	75			534	1907
			3C	50			50	579	2161
3D	75	25			579	2314
			3E	100			0	358	1424

As is apparent from the data presented in Table 3, Fe (NO) is contained₃)₃The compositions exhibit removal rates that are significantly better than those exhibited by compositions that do not contain Fe (NO)₃)₃The removal rate of the composition of (1). In particular, with Fe (NO)₃)₃And the solid compositions containing about 25-75% fumed silica and 25-75% condensation polymerized silica (compositions 3B, 3C, and 3D) had better removal rates than compositions containing Fe (NO)₃)₃And the removal rate of compositions containing 100% fumed silica or 100% solids of condensation polymerized silica (compositions 3A and 3E). These results demonstrate the importance of combining the chemical accelerator with a mixture of fumed metal oxide and abrasive particles having the particle size characteristics described herein, and the proportion of fumed metal oxide to abrasive particles, at the removal rates achieved with the compositions of the invention.

Example 4

This example illustrates the importance of the distribution of abrasive particle sizes in the composition of the invention to maximize surface removal rate during surface planarization or polishing.

Nickel-phosphorous silicon wafers were polished separately with nineteen different compositions each having 25 wt% of Hydroxyl Ammonium Nitrate (HAN) and a total solids concentration of 4 wt.%, wherein the solids contained different concentrations of fumed silica (1.6 wt.%, 2.4 wt.%, and 3.2 wt.% of the composition, respectively, or 40 wt.%, 60 wt.%, and 80 wt.% of the total solids), and different concentrations of condensation polymerized silica (2.4 wt.%, 1.6 wt.%, and 0.8 wt.% of the composition, respectively, and 60 wt.%, 40 wt.%, and 20 wt.% of the total solids), and the condensation polymerized silica had nominal 20, 40, and 80nm particles of condensation polymerized silica (i.e., 0, 0.4, 0.8, 1.2, 1.6, and 2.4 wt.% of the composition) at different relative concentrations. The pH of all compositions was about 3.5. The fumed silica is Cab-O-Sperse^RSC-E fumed silica in the form of an aqueous dispersion (Cabot corporation) was added to the composition. Condensation polymerized silica 20nm, 40nm and 80nm are products 1050, PR-4219 and 2329 (Nalco), respectively. The nominal 20nm particle size of the condensation polymerized silica particles is about 25 nm and σ_gThe value was 1.20. The average particle size of the condensation polymerized silica particles of nominal 40nm is about 46 nm and σ_gThe value was 1.22. The nominal 80nm particle size of the condensation polymerized silica particles is about 78 nm and σ_gThe value was 1.16. Condensation polymerized silica is a commercially available material in which 90% or more by number of its particles have a particle size of not more than 100 nm and about 90% or more by number of its particles have a particle size of not less than about 5 nm. After using the polishing compositions, the removal rates for each composition were determined and the data obtained are set forth in Table 4 below.

TABLE 4

Composition comprising a metal oxide and a metal oxide	Weight percent fumed silica	Nominal 20nm silica weight percent	Nominal 40nm silica weight percent	Nominal 80nm silica weight percent	Removal rate [ Angstrom/min ]]
						4A1	3.2	0.8	0	0	1471
4A2	3.2	0	0.8	0	1326
						4A3	3.2	0	0	0.8	1634
4B1	2.4	1.6	0	0	1021
						4B2	2.4	0	1.6	0	1474
4B3	2.4	0	0	1.6	1639
						4C1	1.6	2.4	0	0	826
4C2	1.6	0	2.4	0	788
						4C3	1.6	0	0	2.4	1123
4D1	3.2	0.4	0.4	0	1748
						4D2	3.2	0.4	0	0.4	1855
4D3	3.2	0	0.4	0.4	1685
						4E1	2.4	0.8	0.8	0	1324
4E2	2.4	0.8	0	0.8	1283
						4E3	2.4	0	0.8	0.8	1484
4F1	1.6	1.2	1.2	0	1207
						4F2	1.6	1.2	0	1.2	1242
4F3	1.6	0	1.2	1.2	1143
						4G1	3.2	0.267	0.267	0.267	2002

As is evident from the data set forth in Table 4, the removal rates exhibited by compositions comprising hydroxylamine nitrate and solids comprising mixtures of fumed silica and condensation polymerized silica vary significantly with the particle size of the condensation polymerized silica. These results demonstrate that the distribution of abrasive particle size in the compositions of the invention affects the removal rate of the composition.

Example 5

This example illustrates the combination and ratio of fumed metal oxide to abrasive particles in the compositions of the invention, and the importance of the presence of a chemical accelerator to maximize the removal rate of the metal surface during surface planarization or polishing.

The tungsten layer was polished separately with five different compositions, all having 4 wt.% hydrogen peroxide, 0.005 wt.% Fe (from ferric nitrate), 0.05 wt.% glycine, 0.03 wt.% malonic acid, and a total solids concentration of 2 wt.%, wherein the solids contained different concentrations of fumed silica (i.e., 0 wt.%, 60 wt.%, 75 wt.%, 90 wt.%, and 100 wt.%), and different relative concentrations of condensation polymerized silica (i.e., 100 wt.%, 40 wt.%, 25 wt.%)wt.%, 10 wt.%, and 0 wt.%) (measured as average particle size of about 40nm, σ)_g1.22). The pH of all compositions was about 2.3. Fumed silica is added to the composition as an aqueous dispersion of Cab-O-Sil  LM-150 fumed silica (Cabot corporation). The condensation polymerized silica was PR-4291(Nalco), wherein the average particle size of a condensation polymerized silica particle of nominally 40 nanometers was about 46 nanometers and σ_gThe value was 1.22. After using the polishing compositions, the removal rate of each composition was measured, and the results are set forth in Table 5.

TABLE 5

Composition comprising a metal oxide and a metal oxide	Relative weight percent fumed silica	Relative weight percent of condensed silica	Removal rate [ Angstrom/min ]]
				5A	0	100	2062
5B	60	40	2001
				5C	75	25	2046
5D	90	10	2715
				5E	100	0	2234

As is evident from the data set forth in table 5, the composition having solids containing about 90 wt.% fumed silica and 10 wt.% condensation polymerized silica (composition 5D) exhibited significantly better removal rates than the compositions having 100 wt.% fumed silica or 100 wt.% condensation polymerized silica (compositions 5A and 5E). These results demonstrate the importance of combining fumed metal oxide and abrasive particles having the particle size characteristics described herein, and the ratio of fumed metal oxide to abrasive particles, at the removal rates achieved with the compositions of the invention.

Example 6

This example illustrates the combination and proportion of fumed metal oxide and abrasive particles in the composition of the invention, and the importance of combining chemical accelerators to maximize surface removal rate during surface planarization or polishing.

Nickel-phosphorus plated memory or hard disks are made using five types of fumed silica (i.e., 0 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, and 4 wt.%) and condensation polymerized silica (i.e., 4 wt.%, 3 wt.%, 2 wt.%, 1 wt.%, and 0 wt.%) having a total solid concentration of 4 wt.% (measured as average particle size of about 20nm, σ%_g＝2.26)，1.5 wt.% of a first chemical accelerator (i.e., H)₂O₂) And 1 wt.% of a second chemical accelerator (i.e., glycine) were polished separately. The pH of all compositions was about 2.5. The fumed silica is Cab-O-Sperse^RSC-1 fumed silica in the form of an aqueous dispersion (Cabot corporation) was added to the composition. The condensation polymerized silicon oxide is Bindzil^R50/80(Akzo-Nobel), wherein 90% or more by number of the particles thereof have a particle size no greater than 100 nm and about 90% or more by number of the particles thereof have a particle size no less than about 5 nm. Following use of the polishing compositions, the removal rates for each composition, as well as the relative removal of each composition, were determined and the data obtained are set forth in Table 6 below.

TABLE 6

Composition comprising a metal oxide and a metal oxide	Weight percent fumed silica	Weight percent of condensation polymerized silica	Weight% H2O2	Weight% Glycine	Removal rate [ Angstrom/min ]]
						6A	0	4	1.5	1	1676
6B	1	3	1.5	1	2134
						6C	2	2	1.5	1	2388
6D	3	1	1.5	1	2464
						6E	4	0	1.5	1	432

From the data set forth in Table 6It is apparent that it contains H₂O₂Glycine, and compositions comprising fumed silica and solid mixtures of condensation polymerized silica (compositions 6B, 6C, and 6D) exhibited removal rates that were significantly better than those exhibited by the H-containing compositions₂O₂Glycine and 4 wt.% fumed silica or 4 wt.% condensation polymerized silica (compositions 6A and 6E). These results demonstrate the importance of the combination and specific ratios of fumed metal oxide to abrasive particles, as well as the inclusion of two or more chemical accelerators, at the removal rates achieved with the compositions of the invention.

Example 7

This example illustrates the combination and proportion of fumed metal oxide and abrasive particles in the composition of the invention, and the importance of combining chemical accelerators to maximize surface removal rate during surface planarization or polishing.

Nickel-phosphorus plated memory or hard disks were made using five fumed silica (i.e., 0 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, and 4 wt.%) and condensation polymerized silica (i.e., 4 wt.%, 3 wt.%, 2 wt.%, 1 wt.%, and 0 wt.%) having a total solid concentration of 4 wt.% (measured as average particle size of about 20nm, σ%_g2.26), 1.5 wt% of a first chemical accelerator (i.e. H)₂O₂) And 1 wt.% of a second chemical accelerator, i.e., Sodium Tripolyphosphate (STP), were polished separately. The pH of all compositions was about 2.5. The fumed silica is Cab-O-Sperse^RSC-1 fumed silica in the form of an aqueous dispersion (Cabot corporation) was added to the composition. The condensation polymerized silicon oxide is Bindzil^R50/80(Akzo-Nobel), wherein 90% or more by number of the particles thereof have a particle size no greater than 100 nm and about 90% or more by number of the particles thereof have a particle size no less than about 5 nm. Following use of the polishing compositions, the removal rates for each composition, as well as the relative removal of each composition, were determined and the data obtained are set forth in Table 7 below.

TABLE 7

Composition comprising a metal oxide and a metal oxide	Weight percent fumed silica	Weight percent of condensation polymerized silica	Weight% H2O2	Weight% STP	Removal rate [ Angstrom/min ]]
						7A	0	4	1.5	0.5	1702
7B	1	3	1.5	0.5	1753
						7C	2	2	1.5	0.5	1930
7D	3	1	1.5	0.5	2311
						7E	4	0	1.5	0.5	356

As is evident from the data set forth in Table 7, H is contained₂O₂STP, and compositions comprising fumed silica and solid mixtures of condensation polymerized silica (compositions 7B, 7C and 7D) exhibited removal rates that were significantly better than those exhibited by H-containing silica₂O₂STP, and 4 wt.% fumed silica or 4 wt.% condensation polymerized silica (compositions 7A and 7E). These results demonstrate the importance of the combination and specific ratios of fumed metal oxide to abrasive particles, as well as the inclusion of two or more chemical accelerators, at the removal rates achieved with the compositions of the invention.

All references, including patents, patent applications, and publications, cited herein are hereby incorporated by reference.

While the invention has been described in terms of specific embodiments with emphasis on the preferred embodiments, those skilled in the art will recognize that variations of the preferred embodiments may be used and that the invention may be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications encompassed within the spirit and scope of the invention as defined by the following claims.

Claims (26)

1. A composition for planarizing or polishing a surface comprising (a) a liquid carrier, (b) a chemical accelerator, and (c) solids comprising 5-90 wt.% fumed metal oxide and 10-95 wt.% abrasive particles, wherein 90% or more of the abrasive particles (by number) have a particle size no greater than 100 nm.

2. The composition of claim 1 wherein the solids have a bulk density of at least 0.1.

3. The composition of claim 2 wherein the solids have a bulk density of at least 0.3.

4. A composition as claimed in any one of claims 1 to 3, wherein the solids comprise 10 to 85% by weight fumed metal oxide and 15 to 90% by weight abrasive particles.

5. A composition according to claim 4, wherein the solids comprise 15 to 75 wt% fumed metal oxide and 25 to 85 wt% abrasive particles.

6. A composition according to any one of claims 1 to 5 wherein the fumed metal oxide is fumed silica.

7. The composition of any of claims 1-6, wherein the abrasive particles are condensation polymerized silica particles.

8. The composition of any of claims 1-7, wherein 95% or more of the abrasive particles (by number) have a particle size no greater than 100 nm.

9. The composition of claim 8, wherein 98% or more of the abrasive particles (by number) have a particle size no greater than 100 nm.

10. The composition of claim 9, wherein substantially all of the abrasive particles (by number) have a particle size no greater than 100 nm.

11. The composition of any of claims 1-10, wherein 90% or more of the abrasive particles (by number) have a particle size of not less than 5 nm.

12. The composition of claim 11, wherein 95% or more of the abrasive particles (by number) have a particle size of not less than 5 nm.

13. The composition of claim 12, wherein 98% or more of the abrasive particles (by number) have a particle size of not less than 5 nm.

14. The composition of claim 13, wherein substantially all of the abrasive particles (by number) have a particle size no less than 5 nm.

15. The composition of any of claims 1-14, wherein the abrasive particles have an abrasive particle size distribution characterized by a geometric standard deviation by number (σ)_g) At least 1.3.

16. A composition as claimed in any one of claims 1 to 15 wherein the solids are present in a concentration of from 0.1 to 40% by weight of the composition.

17. A composition as claimed in any one of claims 1 to 16 wherein the carrier is water.

18. A composition according to any one of claims 1 to 17 wherein the chemical accelerator is a sulphate, persulphate or nitrate.

19. The composition of claim 18 wherein the chemical accelerator is selected from the group consisting of ammonium persulfate, iron (III) nitrate, and hydroxylamine nitrate.

A composition according to any one of claims 1 to 19 wherein the composition includes two or more chemical accelerators.

21. The composition of claim 20 wherein the composition comprises an oxidizing agent and a complexing agent.

22. The composition of claim 21 wherein the complexing agent is selected from the group consisting of amine-containing compounds, phosphate ion sources, phosphonate ion sources, carboxylates, and combinations thereof.

23. The composition of claim 22, wherein the composition comprises hydrogen peroxide or glycine.

A method of planarizing or polishing a surface comprising contacting the surface with the composition of any of claims 1-23.

25. The method of claim 24, wherein the surface is a surface of a memory or a hard disk.

26. The method of claim 25, wherein the surface of the memory or the hard disk is a nickel-phosphorous surface.