Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F3/00—Brightening metals by chemical means
  • C23F3/04—Heavy metals
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/113—Silicon oxides; Hydrates thereof
  • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
  • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
  • C01B33/141—Preparation of hydrosols or aqueous dispersions
  • C01B33/142—Preparation of hydrosols or aqueous dispersions by acidic treatment of silicates
  • C01B33/143—Preparation of hydrosols or aqueous dispersions by acidic treatment of silicates of aqueous solutions of silicates
  • C01B33/1435—Preparation of hydrosols or aqueous dispersions by acidic treatment of silicates of aqueous solutions of silicates using ion exchangers
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B33/00—Silicon; Compounds thereof
  • C01B33/113—Silicon oxides; Hydrates thereof
  • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
  • C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
  • C01B33/146—After-treatment of sols
  • C01B33/148—Concentration; Drying; Dehydration; Stabilisation; Purification
  • C01B33/1485—Stabilisation, e.g. prevention of gelling; Purification
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09G—POLISHING COMPOSITIONS; SKI WAXES
  • C09G1/00—Polishing compositions
  • C09G1/02—Polishing compositions containing abrasives or grinding agents
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
  • C09K3/1454—Abrasive powders, suspensions and pastes for polishing
  • C09K3/1463—Aqueous liquid suspensions
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
  • C09K3/14—Anti-slip materials; Abrasives
  • C09K3/1454—Abrasive powders, suspensions and pastes for polishing
  • C09K3/1472—Non-aqueous liquid suspensions
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/80—Compositional purity
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P52/00—Grinding, lapping or polishing of wafers, substrates or parts of devices
  • H10P52/40—Chemomechanical polishing [CMP]
  • H10P52/403—Chemomechanical polishing [CMP] of conductive or resistive materials
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10P—GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
  • H10P95/00—Generic processes or apparatus for manufacture or treatments not covered by the other groups of this subclass
  • H10P95/06—Planarisation of inorganic insulating materials
  • H10P95/062—Planarisation of inorganic insulating materials involving a dielectric removal step

Definitions

• the present invention relates to a method of manufacturing of an ultrapure colloidal silica dispersion and slurry thereof. More particularly, the present invention relates to a method of chemical mechanical polishing (CMP) the surface of a substrate using such ultrapure colloidal silica prepared according to the present invention.
• CMP chemical mechanical polishing
• colloidal silica The most common process for the preparation of colloidal silica in industry is to prepare colloidal silica particles from water glass made by fusion of natural silica sands with sodium carbonate at temperature less than 1200 0 C. After fusion, the fused sodium silicate is quenched and completely dissolved in water, forming water glass that is highly caustic. To process colloidal silica, the water glass is further passed through a strong acidic resin bed or column for ion exchange and converted into silicic acid. The silicic acid, normally around pH 2-3, is then placed in a container, the pH adjusted to about 8 using alkali for stabilization, and then heated to an elevated temperature, 80-100 0 C for particle formation.
• the particle size distribution of the final product can be manipulated and controlled to be from 5 nm to about 100 nm or less. Because of the nature of the raw material, silica sands, however, the final colloidal silica from this process has more or less trace metals, such as Fe, Al, and Na, from 100 ppm to 1000 ppm or less.
• TMOS tetramethoxy silane
• TEOS tetraethoxy silane
• the solution is heated to a high temperature so that the ammonia and the organic solvent can be removed by evaporation (W. Stober, et al., J. Colloid Interface Sci., 26, 62 (1968)).
• the colloidal silica so processed has a very high purity because of the high purity of the raw materials.
• colloidal silica from this process is much more expensive because of the highly expensive raw materials. Secondly, large quantity of impure methanol or ethanol will be generated which is not environmental friendly. Finally, the colloidal silica can have high level of ammonia and organic solvent residual, which can be very undesirable for chemical mechanical polishing (CMP) applications. Colloidal silica comes in different sizes and shapes. The main benefit of colloidal silica over fumed silica is that they can generate very small particles, as small as 5 to 10 nm. Also colloidal silica can be well dispersed to the primary spherical particles while fumed silica particles are always aggregated. In the area of chemical mechanical polishing (CMP), this translates to very low defectivity and high removal rates on certain metals.
• CMP chemical mechanical polishing
• TEOS TEOS
• TMOS TMOS
• 3 parts of TEOS generates approximately 1 part of silica and two parts of impure ethanol (TEOS is composed of 28%SiO2-72%EtOH).
• the fumed silicas are generally quite pure. These are solid particles ranging from 75 to 300 nm mean particle size (MPS) with primary particles size around 20 to 40nm. But unlike colloidal silica (which are solution grown) they have to be made into chemical mechanical polishing (CMP) slurries by high shear grinding process using water, wetting and stabilizing agents. In addition these dispersions need filtration to remove large particles. Thus, although the fumed silica is low to moderate in cost, the final dispersion can be relatively expensive. Other issue with the fumed silica is they cause high CMP defectivity In commonly assigned copending U.S. Patent Application, Serial No.
• This method includes the steps of dissolving a fumed silica in an aqueous solvent containing an alkali metal hydroxide to produce an alkaline silicate solution, such as, a potassium silicate solution; removing the majority of alkali ions via ion exchange to produce a silicic acid solution; adjusting the temperature, concentration and pH of the silicic acid solution to values sufficient to initiate nucleation and particle growth; and cooling the silicic acid solution sufficiently to produce the colloidal silica dispersion.
• the colloidal silica particles in the colloidal silica dispersion have a primary particle size about 2 nm to about 100 nm, and a mean particle size (MPS) of 20 to 200 nm.
• step 1 has some Cl ion in the slurry, it can contaminate the step 2 slurry and change the polish performance. It should be noted that many commercial Cu and barrier slurries are relatively pure having trace metals at less than 1 ppm level.
• the present invention provides a method of chemical mechanical polishing a surface of a substrate.
• the method includes the step of: contacting a substrate; and a composition which includes: (i) a plurality of colloidal silica particles having less than 200 ppb of each trace metal impurity, excluding potassium and sodium, have less than 2 ppm residual alcohol and wherein the cumulative trace metal concentration, excluding potassium and sodium, is in the range from about 0.5 to about 5 ppm; and
• composition is an ultrapure colloidal silica dispersion; and wherein the contacting is carried out at a temperature and for a period of time sufficient to planarize the substrate.
• the present invention further provides a ultrapure colloidal silica dispersion including colloidal silica particles having a mean or aggregate particle size from about 10 to about 200nm, wherein the colloidal silica dispersion has less than 200 ppb of each trace metal impurity disposed therein, excluding potassium and sodium, and have less than 2 ppm residual alcohol.
• the present invention still further provides a method of manufacturing an ultrapure colloidal silica dispersion, including the steps of: dissolving a fumed silica in an aqueous solvent containing an alkali metal hydroxide to produce an alkaline silicate solution; removing majority of the alkali metal via ion exchange to produce a silicic acid solution; adjusting temperature, concentration and pH of the silicic acid solution to values sufficient to initiate nucleation and particle growth; and cooling the silicic acid solution to produce the colloidal silica dispersion.
• the present invention also provides a method of chemical mechanical polishing a surface of a substrate including the step of: contacting the substrate and an ultrapure colloidal silica dispersion including colloidal silica particles having a mean or aggregate particle size from about 10 to about 200nm, and wherein the colloidal silica dispersion has less than 200 ppb of each trace metal impurity, excluding potassium and sodium, and have less than 2 ppm residual alcohol; wherein the contacting is carried out at a temperature and for a period of time sufficient to planarize the substrate.
• the present invention additionally provides a potassium silicate solution having less than 200 ppb of each trace metal impurity disposed therein, excluding K and Na, and less than 2 ppm residual alcohol.
• Fig. 1 is a graph plotting normalized data for CuIOK-SPF with contaminants.
• Fig. 2 is a graph plotting normalized data for polishing CuIOK-SPF with contaminants.
• Figs. 3 is a graph plotting ER8071 Slurry with contaminants.
• Fig. 4 is a graph plotting data for polishing ER8071 with contaminants.
• Fig. 5 is graph plotting normalized data for polishing CuIOK-SPF with contaminants.
• Fig. 6 is a graph plotting normalized data for CuI OK-SPF with contaminants.
• Fig. 7 is a graph plotting data for polishing ER8071 with contaminants.
• Figs. 8 is a graph plotting ER8071 Slurry with contaminants.
• Fig. 9 is a graph plotting corrosion rates of CuIOK-SPF and ER8071 samples.
• Fig. 10 is a graph plotting cyclic polarization comparison of contaminated CuIOK-SPF samples.
• Fig. 11 is a graph plotting cyclic polarization comparison of ER8071 samples.
• the cumulative amount of trace metal impurities present in such ultrapure slurries according to the present invention is in the range from about 0.5 to about 5 ppm, more preferably from about 1 to about 3 ppm.
• Such ultrapure slurries exhibit novel removal rates with a decrease in defects.
• Such slurries may optionally include a stablizer ion, such as, potassium.
• the colloidal silica particles are from about 0.2 wt% to about 45 wt% of the total weight of the composition, more preferably from about 2 wt% to about 24 wt%.
• the colloidal silica particles have a surface area from about 20 m 2 /g to about 300 m 2 /g.
• the composition further includes a surfactant selected from anionic, cationic, non-ionic and amphoteric surfactants and a mixture thereof.
• the surfactant is an alkoxylated non-ionic surfactant.
• the composition further includes at least one additive selected from carboxylic acid, at a concentration of about 0.01 wt% to about 0.9 wt%; oxidizer, at a concentration of about 10 ppm to about 2.5%, more preferably from about 10 ppm to about 2500 ppm; and corrosion inhibitor, at a concentration of about 10 ppm to about 1000 ppm.
• carboxylic acid at a concentration of about 0.01 wt% to about 0.9 wt%
• oxidizer at a concentration of about 10 ppm to about 2.5%, more preferably from about 10 ppm to about 2500 ppm
• corrosion inhibitor at a concentration of about 10 ppm to about 1000 ppm.
• the composition is in a form selected from an emulsion, colloidal suspension, solution and slurry.
• the medium is from about 1 wt% to about 86 wt% of the total weight of the composition.
• the medium has a pH bout 2 to about 11.
• the medium is selected from water, an organic solvent and a mixture thereof.
• the colloidal silica dispersion is used as the chemical mechanical polishing composition without isolating the colloidal silica particles from the colloidal silica dispersion.
• the alkali metal hydroxide is potassium hydroxide.
• the colloidal silica particles are prepared by dissolving a funned silica in an aqueous solvent including an alkali metal hydroxide to produce a alkaline silicate solution, removing the alkali metal via ion exchange to convert the alkaline silicate solution to a silicic acid solution, adjusting temperature, concentration and pH of the silicic acid solution to values sufficient to initiate nucleation and particle growth, and cooling the silicic acid solution at a rate sufficient to produce a colloidal silica dispersion; and isolating the colloidal silica particles from the colloidal silica dispersion to produce colloidal silica particles having a mean or aggregate particle size about 10 nm to about 200 nm and metals selected from Li, Rb, Cs, Fr, Fe, Al, and any combinations thereof, at a total metals concentration of about lO ppm or less.
• the trace metal is present within the dispersion in the range from about 5 to about 200 ppb, excluding sodium which may be present in an amount of less than 1 ppm. Moreover, the cumulative trace metal concentration of the dispersion, excluding potassium, is in the range from about 1 to 5 ppm, more preferably about 1 to about 3 ppm.
• the chemical mechanical polishing slurry contains less than 200 ppb of amines, such as, ammonia.
• the present invention provides a method of manufacturing a colloidal silica dispersion, including the steps of: dissolving a fumed silica in an aqueous solvent containing an alkali metal hydroxide to produce an alkaline silicate solution; removing majority of the alkali metal via ion exchange to produce a silicic acid solution, adjusting temperature, concentration and pH of the silicic acid solution to values sufficient to initiate nucleation and particle growth; and cooling the silicic acid solution to produce the colloidal silica dispersion.
• the colloidal silica particles can be isolated from the colloidal silica dispersion to produce solvent free colloidal silica particles.
• the dispersion is typically used "as is” or by adding other ingredients, such as, organic solvents, additives and surfactants to produce a composition that is suitable for use for chemical mechanical polishing of surfaces of a substrate.
• the colloidal silica dispersion can be concentrated from the original colloidal silica dispersion either by removing the aqueous solvent or, more preferably, by filtering the colloidal silica particles, and thereafter drying.
• the colloidal silica particles prepared by the method of the present invention have a mean or aggregate particle size (MPS) about 10 nm to about 200 nm.
• the colloidal silica particles have a total metals concentration of about 300 ppm or less.
• the metals can be Li, Rb, Cs 1 Fr, Fe, Al, or any combinations thereof. More preferably, the concentration of these metals is about 10 ppm or less.
• fumed silica starting material is dissolved in an aqueous solvent, such as, an aqueous alkali, alcohol, or a combination thereof, to produce an alkali silicate solution.
• an aqueous solvent such as, an aqueous alkali, alcohol, or a combination thereof
• majority of the alkali is removed by ion exchange so that the alkaline silicate solution is converted into a silicic acid solution.
• the temperature, the concentration and the pH of this solution, which is a silicic acid solution is then adjusted to values such that the selected values cause the solution to initiate nucleation and allow the nucleated particles to form the colloidal silica dispersion.
• the temperature of the silicic acid solution before the start of the nucleation is about 5 0 C to about 40 0 C.
• the concentration of the silicic acid in the silicic acid solution before the start of the nucleation is about 2 wt% to about 30 wt% of the silicic acid solution.
• the pH of the silicic acid solution is about 1.5 to about 5, and more preferably from 1.5 to about 4.0.
• the cooling rate of the silicic acid solution is about 5 °C/min to about 100 °C/min.
• the high purity colloidal silica dispersion made as set forth above is then admixed with semiconductor grade raw materials, e.g., hydrogen peroxide, BTA, KOH, organic acids, etc., to make a final slurry product having ultrapure purity.
• semiconductor grade raw materials e.g., hydrogen peroxide, BTA, KOH, organic acids, etc.
• the present inventors mixed some contaminants into CuIOK-SPF (i.e., a commercial barrier layer polishing slurry manufactured and sold by Planar Solutions Inc., which includes 10% fumed silica, KOH, a corrosion inhibitor and hydrogen peroxide as an oxidizer and ER8071 , i.e., an experimental barrier layer slurry with 6.75% ultra pure colloidal silica particles, KOH, a corrosion inhibitor, a surfactant and hydrogen peroxide. That is, the present inventors used the ultrapure colloidal silica dispersion made by the aforementioned manufacturing process. In addition, the present inventors, used semiconductor grade raw materials, e.g., hydrogen peroxide or BTA (as a corrosion inhibitor) to make final slurry products.
• CuIOK-SPF i.e., a commercial barrier layer polishing slurry manufactured and sold by Planar Solutions Inc., which includes 10% fumed silica, KOH, a corrosion inhibitor and hydrogen peroxide as an oxidizer and ER80
• Figures 1 and 2 attached hereto, provide data when CuIOK-SPF was a control and wherein fixed amounts of ammonia (100 ppm), alumina (5 ppm) and methanol (150 ppm) were added and then various properties were tested. These tests demonstrated that ammonia increased copper removed rates and slightly increased defectivity. Also, alumina increased LPCs and defectivity dramatically. Furthermore, methanol increased the C LPCs (large particle counts) significantly.
• FIGS 3 and 4 attached hereto, provide data when ER8071 slurry was used and wherein fixed amounts of ammonia (100 ppm), alumina (5 ppm) and methanol (150 ppm) were added and then various properties were tested. These tests demonstrated that ammonia increased the copper removal rates. Alumina increased the LPCs and defectivity and methanol increased the defectivity and LPCs.
• Figures 5-8 include data generated from a second screening of contaminants in both fumed silica and FCC particles.
• Aluminum oxide from Example 1 was replaced with aluminum chloride, as well as the colloidal silica particle was replaced with FCC particles.
• Figures 5 and 6 attached hereto provide data when CuIOK-SPF was a control and wherein fixed amounts of ammonia (100 ppm), alumina (5 ppm), methanol (150 ppm), NaOH (5 ppm), ethanol (150 ppm) and a mixture of contaminants were added and then various properties were tested.
• the first set of data shows normalized data for polishing Cu, Ta, TEOS and defects. These tests demonstrated that copper removal rate increased with ammonia addition, and defects decreased. Not much change with methanol samples was observed.
• the aluminum chloride sample showed higher defects than the control.
• the NaOH gave much higher defects, as did the ethanol sample.
• the sample with all contaminants gave slightly higher copper removal rate and defects.
• Figures 7 and 8, attached hereto, provide data when ER8071 slurry was used and wherein fixed amounts of ammonia (100 ppm), alumina (5 ppm), methanol (150 ppm), NaOH (5 ppm), ethanol (150 ppm) and a mixture of contaminants were added and then various properties were tested. As far as the FCC/ER8071 samples go there was a lot less affected. The defects were very high with the addition of ammonia, and lower defects with the 'worse case' sample. The rates did not seem to change much.
• the fumed silica samples are undesirable as far as LPCs. Defectivity and copper rates are the main factors affected by polishing samples with contaminants. When contaminants are added, the FCC particle is not influenced much when running Nicomp and colloidal dynamics. FCC particles with contaminants may cause defectivity to increase, but rates generally remain constant.
• Figures 9-11 depict the effects of impurities in CuIOK-SPF and ER8071 on their respective copper corrosion characteristics.
• the samples in the figures included a CuIOK-SPF as the control, the control contaminated with 100 ppm (wt/wt) ammonium hydroxide, 150 ppm (wt/wt) methanol, 5 ppm (wt/wt) aluminum chloride, 5 ppm (wt/wt) sodium hydroxide respectively, and one control included all the above contaminants together.
• the two ER8071 samples were with identical chemistry, only different on the abrasive particles: one with a TMOS based colloidal silica which is known to have less than 200 ppb individual trace metals but with certain levels of alcohol and ammonia impurities, the other with a type of FCC colloids.
• Figure 9 shows the corrosion rates calculated using the Stern- Geary equation based on data acquired with linear polarization and the Tafel plots of the samples. Both ammonia and aluminum chloride more than doubled the corrosion rate of the CuIOK-SPF slurry. Addition of all the aforementioned contaminants together had led to synergetic increase of copper corrosion rate and deterioration of passivation protection (see Figure 10).
• Figure 11 is the cyclic polarization comparison of the two ER8071 samples. It displayed the decrease of corrosion protection on copper surface when the TMOS based abrasives were used, in agreement with the corrosion rate calculation (Figure 9).
• the present inventors have unexpectedly discovered that tiny amounts of impurities can have a significant effect on removal rates, LPCs and defectivity, and that ultrapure slurries, according to the present invention, have better overall performance than conventional slurries.
• the present invention provides a method of chemical mechanical polishing a substrate.
• the method includes the step of contacting the substrate and a composition having a plurality of colloidal silica particles according to the present invention and a medium for suspending the particles.
• the contacting is carried out at a temperature and for a period of time sufficient to planarize the substrate.
• the particles can be suspended or dispersed in a variety of mediums to produce a polishing composition.
• the particles may proportionately include a greater concentration of larger size or primary particles, with a lesser concentration of smaller size or secondary particles. The result of this size variation is an improved removal rate of surface impurities and controlled surface topography not provided by conventional polishes.
• the composition can further include an additive selected from a carboxylic acid or a mixture of carboxylic acids present in a concentration of about 0.01 wt% to about 0.9 wt%; an oxidizer, present in a concentration of about 10 ppm to about 250,000 ppm and preferably, present in a concentration of about 10 ppm to about 1000 ppm; and a corrosion inhibitor, present in the range of about 10 ppm to about 1000 ppm.
• an additive selected from a carboxylic acid or a mixture of carboxylic acids present in a concentration of about 0.01 wt% to about 0.9 wt%
• an oxidizer present in a concentration of about 10 ppm to about 250,000 ppm and preferably, present in a concentration of about 10 ppm to about 1000 ppm
• a corrosion inhibitor present in the range of about 10 ppm to about 1000 ppm.
• the composition includes primary particles having a mean particle size from about 2 nm to about 200 nm.
• the composition can be in the form of an emulsion, a colloidal suspension, a solution, and a slurry in which the particles are uniformly dispersed and are stable both in a basic or acidic pH environment and includes a surfactant.
• the composition can include a cationic, anionic, non-ionic, amphoteric surfactant or a mixture thereof. More preferably, the composition includes a non-ionic surfactant, used to significantly reduce surface removal rates to about 50 ppm.
• the preferred non-ionic surfactant is an alkoxylated non-ionic surfactant.
• the beneficial effects of the surfactants include a reduction in polishing friction.
• an upper limit of about 1000 ppm because at this level, organic residue, defectivity is observed on the wafer surfaces. Therefore, a non-ionic surfactant is preferred because of its inert reactivity towards other films, such as those having Cu and Ta.
• the particles in the composition also have a low level of trace metals, such as, Fe, Al, Li, Rb, Cs, and F.
• the colloidal silica particles have a total metals concentration of about 300 ppm or less.
• the metals can be Fe, Al, Li, Rb, Cs, Fr, or any combinations thereof. More preferably, the concentration of these metals is about 10 ppm or less. Most preferably, the concentration of these metals is about 2 ppm or less, except for K, which can be used as stabilizer, or Na.
• silica particles having surface area from about 20 m 2 /g to about 300 m 2 /g are from about 1 wt% to 20 wt% of the total weight of the composition and the medium is about 81 wt% to 99 wt% of the composition.
• the medium can be water, an alkaline solution, an organic solvent or a mixture thereof.
• the medium can be in the form of an emulsion, colloidal suspension, or slurry.
• the medium of the polishing composition can include an aqueous organic solvent, such as, an aqueous alcohol, an aqueous ketone, an aqueous ether, an aqueous ester, or a combination thereof.
• an aqueous organic solvent such as, an aqueous alcohol, an aqueous ketone, an aqueous ether, an aqueous ester, or a combination thereof.
• the preferred medium is an aqueous alcohol, wherein the alcohol preferably is methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, or a mixture thereof.
• the medium can be the same as or different from the aqueous organic solvent typically employed in the process of manufacturing a colloidal silica dispersion according to the present invention.
• the colloidal silica dispersion can be used as the chemical mechanical polishing composition without isolating the colloidal silica particles from the colloidal silica dispersion.
• the pH of the polishing composition is maintained in a range from about 9.0 to about 11 or in acidic region of about 2.0 to about 4.0.
• the present invention also encompasses particular made from dehydrated slurries.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Dispersion Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Mechanical Treatment Of Semiconductor (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
• Silicon Compounds (AREA)

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• 2006
  • 2006-09-22 EP EP06804066.6A patent/EP1966410B1/en active Active
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