JP4286168B2 - How to reduce nanoscratches - Google Patents

Description

  The present invention relates to a polishing liquid composition and a method for producing a substrate.

  Recent memory hard disk drives are required to have a high capacity and a small diameter, and in order to increase the recording density, the flying height of the magnetic head is reduced to reduce the unit recording area. As a result, the surface quality required after polishing in the manufacturing process of magnetic disk substrates has become stricter year by year, and the surface roughness, micro waviness, roll-off and protrusions have been reduced in response to the low flying height of the head. Corresponding to the decrease in unit recording area, the allowable number of scratches per substrate surface is small, and its size and depth are getting smaller.

  Also in the semiconductor field, high integration and high speed are advancing. In particular, miniaturization of wiring is required for high integration. As a result, in the manufacturing process of a semiconductor substrate, the depth of focus at the time of exposure of the photoresist becomes shallow, and further surface smoothness is desired.

In response to such requirements, a polishing liquid composition with improved surface smoothness of the memory hard disk substrate is described in Patent Document 1, but the surface smoothness necessary for increasing the density of the memory hard disk substrate is obtained. Is insufficient.
JP 2003-193037 A

  Accordingly, the present inventors have conducted extensive studies on the requirements for achieving the surface smoothness necessary for high density or high integration of precision component substrates such as memory hard disk substrates and semiconductor substrates. The occurrence of “nano scratches” (depth scratches of 10 nm or more, less than 100 nm, widths of 5 nm or more and less than 500 nm, and fine scratches on the substrate surface of 100 μm or more) is increased in density on memory hard disk substrates, and semiconductors For the first time, it has been found that the substrate is preventing high integration, and the present invention has been completed.

  That is, an object of the present invention is to provide a polishing composition that has a small surface roughness of the polished object and can significantly reduce nano scratches, and a substrate that has a small surface roughness and significantly reduced nano scratches. It is in providing the manufacturing method of.

That is, the gist of the present invention is as follows.
An aluminum alloy substrate plated with Ni-P using a polishing composition having a pH of 1 to 4 comprising colloidal silica having an average primary particle size of 1 nm to 30 nm and a zeta potential adjuster. The method of reducing the nano-scratch of the Ni-P plated aluminum alloy substrate, comprising the step of adjusting the zeta potential of the colloidal silica in the polishing composition to -10 to 10 mV. Way ,
About.

  By using the polishing composition of the present invention, for example, in a polishing step of a precision component substrate for densification or high integration, the surface smoothness of the substrate after polishing is excellent, and the fineness that could not be detected conventionally is used. Since nano scratches can be remarkably reduced, there is an effect that it is possible to manufacture high-quality memory hard disk substrates having excellent surface properties and precision component substrates such as semiconductor substrates.

  The present invention has excellent surface properties by setting the zeta potential of the abrasive in the polishing composition containing an abrasive having an average primary particle size of 1 nm or more and less than 40 nm to -15 to 30 mV, It is possible to significantly reduce nano scratches that cause defects. This nano-scratch is a physical property that is important for high density or high integration especially in a memory hard disk substrate or a semiconductor substrate. Therefore, by using the polishing composition of the present invention, a high-quality memory hard disk substrate or semiconductor substrate having excellent surface properties can be produced.

  Although the mechanism for reducing this nanoscratch is not clear, the closer the zeta potential of the abrasive is to the isoelectric point, the greater the interparticle attractive force between the abrasive particles, and the coarse or fine particles that are considered to cause scratches during polishing. This is presumed to be due to the suppression of dropout of particle aggregates onto the substrate surface.

  In the present invention, the zeta potential refers to a potential obtained from the migration speed of the abrasive when an electric field is applied from the outside to the abrasive in the polishing composition by the principle of electrophoresis. Examples of the zeta potential measuring device include electrophoresis such as “ELS-8000” (manufactured by Otsuka Electronics), “DELSA440SX” (manufactured by Beckman Coulter), and “NICOMP Model 380” (manufactured by Particle Sizing Systems). An apparatus using the principle is preferred. Further, measurement based on the principle of an ultrasonic method such as “DT1200” (manufactured by Luft) can be substituted. In the measurement based on the principle of electrophoresis, it is necessary to dilute the concentration of the abrasive on the principle of the apparatus. The zeta potential of the abrasive in the polishing liquid composition in the present specification refers to a zeta potential adjusting aqueous solution (preliminarily adjusted to the same pH as the polishing liquid composition (from the zeta potential adjusting agent and water in the polishing liquid composition). However, when the polishing liquid composition contains two or more types of zeta potential regulators, the aqueous solution is prepared by maintaining the content ratio thereof) and the polishing liquid composition is adjusted to have a predetermined concentration. Of zeta potential. In addition, when measuring the zeta potential with the zeta potential measuring device, in order to increase the reliability of the measurement value, the measurement is repeated at least three times under the same sample and the same measurement condition, and the average value thereof is taken as the zeta potential. To do.

  The zeta potential of the abrasive in the polishing composition of the present invention is -15 to 30 mV, and from the viewpoint of reducing nanoscratches, it is preferably -15 to 20 mV, more preferably -15 to 10 mV, and still more preferably -10. -10 mV, more preferably -5 to 5 mV.

  As the abrasive in the present invention, an abrasive generally used for polishing can be used, and examples thereof include metal, metal or metalloid carbide, nitride, oxide, boride, diamond, and the like. It is done. The metal or metalloid element is derived from Group 2A, 2B, 3A, 3B, 4A, 4B, 5A, 6A, 7A or Group 8 of the periodic table (long period type). Specific examples of the abrasive include silicon oxide (hereinafter referred to as silica), aluminum oxide (hereinafter referred to as alumina), silicon carbide, diamond, manganese oxide, magnesium oxide, zinc oxide, titanium oxide, cerium oxide, zirconium oxide, and the like. In addition, the surface of these abrasives may be modified or surface-modified with a functional group, or may be compounded with a surfactant or an abrasive, and the use of one or more of these may reduce surface roughness. To preferred. Further, from the viewpoint of reducing nanoscratches, colloidal particles and fumed silica particles are preferable, and colloidal particles such as colloidal silica, colloidal ceria, and colloidal alumina are particularly preferable. Colloidal silica obtained by is preferable.

  The average particle size of the primary particles of the abrasive is 1 nm or more and less than 40 nm regardless of whether or not one or more abrasives are mixed. From the viewpoint of improving the polishing rate, it is preferably 3 nm or more, more preferably 5 nm or more. Moreover, from the viewpoint of reducing the surface roughness (centerline average roughness: Ra, Peak to Valley value: Rmax), it is preferably 35 nm or less, more preferably 30 nm or less, still more preferably 25 nm or less, and even more preferably 20 nm or less. It is. Therefore, from the viewpoint of economically reducing the surface roughness, the average particle size of the primary particles is preferably 1 to 35 nm, more preferably 3 to 30 nm, still more preferably 5 to 25 nm, and still more preferably 5 to 20 nm. . Furthermore, when primary particles are aggregated to form secondary particles, the average particle size of the secondary particles is preferably from the viewpoint of improving the polishing rate and reducing the surface roughness of the substrate. Is 5 to 150 nm, more preferably 5 to 100 nm, still more preferably 5 to 80 nm, still more preferably 5 to 50 nm, still more preferably 5 to 30 nm.

  The average particle size of the primary particles of the abrasive is small using the image observed with a scanning electron microscope (preferably 3000 to 100000 times) regardless of whether one or more abrasives are mixed. The particle size (D50) at which the integrated particle size distribution (number basis) from the diameter side is 50% is obtained, and this value is taken as the average particle size of the primary particles. Here, the particle diameter of one primary particle is a biaxial average (average of major axis and minor axis). The average particle size of the secondary particles can be measured as a volume average particle size using a laser beam diffraction method.

  In addition, as a particle size distribution of the abrasive, D90 / D50, from the viewpoint of achieving a reduction in nanoscratches, a reduction in surface roughness, and a high polishing rate regardless of whether or not one or more abrasives are mixed. Preferably it is 1-5, More preferably, it is 2-5, More preferably, it is 3-5. In addition, D90 is a particle diameter that uses an image observed with a scanning electron microscope (preferably 3000 to 100000 times), and the cumulative particle size distribution (number basis) from the small particle size side of the primary particles is 90%. Say.

  The content of the abrasive in the polishing composition is preferably 0.5% by weight or more, more preferably 1% by weight or more, still more preferably 3% by weight or more, and further preferably 5% from the viewpoint of improving the polishing rate. From the viewpoint of improving the surface quality, it is preferably 20% by weight or less, more preferably 15% by weight or less, still more preferably 13% by weight or less, and further preferably 10% by weight or less. That is, from the viewpoint of economically improving the surface quality, the content is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, still more preferably 3 to 13% by weight, and still more preferably 5 to 5%. 10% by weight.

  Moreover, the zeta potential adjusting agent contained in the polishing liquid composition of the present invention is an additive for controlling the zeta potential of the surface of the abrasive in the polishing liquid composition. An agent that controls the surface potential of abrasive particles by directly or indirectly adsorbing on the surface of the abrasive particles or by changing properties such as acidity or basicity of the medium. Examples include acids, bases, salts, and surfactants.

  The zeta potential adjusting agent is used as follows, for example. When the zeta potential of the abrasive contained in the polishing composition exceeds 30 mV, it is preferable to use an acid, an acid salt and an anionic activator as the zeta potential adjusting agent and shift the zeta potential to the negative side. On the other hand, when the zeta potential of the abrasive is lower than −15 mV, it is preferable to use a base, a basic salt, and a cationic activator as the zeta potential adjusting agent and shift the zeta potential to the plus side. The zeta potential adjusting agent is a neutral salt, a nonionic active agent, or an amphoteric active agent, which is used when adjusting the zeta potential without changing the pH of the polishing composition.

  As the acid, an inorganic acid or an organic acid is used. Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, amidosulfuric acid and the like. Examples of organic acids include carboxylic acids, organic phosphoric acids, amino acids, and the like. For example, carboxylic acids include monovalent carboxylic acids such as acetic acid, glycolic acid, and ascorbic acid, divalent carboxylic acids such as oxalic acid and tartaric acid, and citric acid. Examples of the organic phosphoric acid include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid). Acid), diethylenetriaminepenta (methylenephosphonic acid) and the like. Examples of amino acids include glycine and alanine. Among these, inorganic acids, carboxylic acids and organic phosphoric acids are preferable from the viewpoint of reducing nanoscratches. For example, nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, glycolic acid, oxalic acid, citric acid, 1-hydroxyethylidene-1,1 -Diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenesulfonic acid), diethylenetriaminepenta (methylenephosphonic acid) are suitable.

  Examples of the base include ammonia water, hydroxylamine, alkylhydroxylamine, primary to tertiary alkylamine, alkylenediamine, alkylammonium hydroxide and the like. From the viewpoint of reducing nanoscratches, ammonia water and alkanolamine are preferable. .

  Examples of the salt include salts of the acids described above, and cations forming the salt include metals derived from groups 1A, 2A, 3B, and 8 of the long-period periodic table, and ammonium, hydroxide ammonium, Or alkanol ammonium is preferable. Among these, examples of the acid salt include ammonium nitrate, ammonium sulfate, aluminum nitrate, aluminum sulfate, and aluminum chloride. Examples of basic salts include sodium citrate, sodium oxalate, sodium tartrate and the like. Examples of the neutral salt include sodium chloride, sodium sulfate, sodium nitrate and the like.

  Surfactants include low-molecular-weight active agents and high-molecular-weight active agents, which are adsorbed or chemically bonded to the surface of the abrasive and have one or more hydrophilic groups in the molecule, regardless of whether they are the same or different. It is. Among them, nonionic active agents having nonionic groups typified by ether groups (oxyethylene groups, etc.) and hydroxyl groups, anionic groups typified by carboxylic acid groups, sulfonic acid groups, sulfate ester groups, and phosphate ester groups And an anionic activator having a cationic group represented by quaternary ammonium, an anionic group and a cationic group.

  Further, as a preferable combination of the abrasive and the zeta potential adjusting agent, when the abrasive is silica, the zeta potential adjusting agent is nitric acid, sulfuric acid, phosphoric acid, polyphosphoric acid, glycolic acid, oxalic acid, citric acid. 1-hydroxy-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenesulfonic acid), diethylenetriaminepenta (methylenephosphonic acid) are preferred, nitric acid, sulfuric acid, phosphoric acid, citric acid, 1-hydroxy More preferred is -1,1-diphosphonic acid.

  When the abrasive is alumina, the zeta potential adjuster is preferably sulfuric acid, ammonium sulfate, phosphoric acid, polyphosphoric acid, oxalic acid, citric acid, 1-hydroxy-1,1-diphosphonic acid, sulfuric acid, ammonium sulfate, Phosphoric acid, polyphosphoric acid, citric acid, and 1-hydroxy-1,1-diphosphonic acid are more preferable.

  The content of the zeta potential adjusting agent in the polishing composition is determined according to the properties of the polishing composition, the properties of the polishing material, and the desired zeta potential. From the viewpoint of reducing scratches, 0.01 to 20% by weight is preferable, and 0.05 to 15% by weight is more preferable. Further, the zeta potential adjusting agent may be previously contained in the polishing liquid composition, or may be used by being included in the polishing liquid composition immediately before polishing.

Moreover, other components can be mix | blended with the polishing liquid composition of this invention as needed. Examples of the other components include oxidizing agents such as hydrogen peroxide, radical scavengers, inclusion compounds, rust inhibitors, antifoaming agents, and antibacterial agents.
The content of these other components is preferably 0 to 10% by weight and more preferably 0 to 5% by weight from the viewpoint of the polishing rate in the polishing composition.

  Furthermore, water and / or a water-soluble organic solvent can be used as the medium in the polishing composition of the present invention. Examples of water include ion-exchanged water, distilled water, and ultrapure water, and examples of the water-soluble organic solvent include primary to tertiary alcohols and glycols. The content of the medium corresponds to the balance obtained by subtracting the content of the abrasive, the zeta potential adjusting agent and other components from 100% by weight. The content of this medium is preferably 60 to 99% by weight and more preferably 70 to 98% by weight in the polishing composition.

  The polishing composition of the present invention can be prepared by appropriately mixing the above components.

  The concentration of each component in the polishing liquid composition may be any of the concentration during production of the composition and the concentration during use. Usually, a polishing composition is produced as a concentrated liquid, and it is often used after being diluted at the time of use.

  The pH of the polishing composition of the present invention is determined according to the polishing material used and the degree of surface modification such as surface modification from the viewpoint of reducing the polishing rate and nanoscratching. In the case of colloidal silica, it is preferably 7 or less, more preferably 5 or less, still more preferably 4 or less, still more preferably 3 or less, still more preferably 2.5 or less, and even more preferably 2 or less.

  By using the polishing composition having such a configuration, it is possible to obtain a substrate for precision parts having excellent surface properties with very few nanoscratches.

  The nano-scratch in the present invention is a fine flaw on the substrate surface having a depth of 10 nm or more, less than 100 nm, a width of 5 nm or more and less than 500 nm, and a length of 100 μm or more, and is detected by an atomic force microscope (AFM). And can be quantitatively evaluated as the number of nano scratches by measurement with “MicroMax” which is a visual inspection apparatus described in Examples described later.

  In addition, although the evaluation method is not limited to the surface roughness which is a measure of surface smoothness, in the present invention, it is evaluated as a roughness that can be measured at a short wavelength of 10 μm or less in an AFM (atomic force microscope), Expressed as centerline average roughness Ra. Specifically, it can be obtained by the method described in Examples below.

  Examples of the material of the object preferably used in the present invention include metals or semimetals such as silicon, aluminum, nickel, tungsten, copper, tantalum, and titanium, or alloys thereof, glass, glassy carbon, and amorphous carbon. Examples thereof include glassy substances such as alumina, silicon dioxide, silicon nitride, tantalum nitride, titanium carbide and other ceramic materials, polyimide resins and the like. Among these, it is suitable for an object to be polished containing a metal such as aluminum, nickel, tungsten, or copper and an alloy containing these metals as a main component. For example, a Ni—P plated aluminum alloy substrate or a glass substrate such as crystallized glass or tempered glass is more suitable, and a Ni—P plated aluminum alloy substrate is more suitable.

  The shape of the object to be polished is not particularly limited. For example, the shape having a flat portion such as a disk shape, a plate shape, a slab shape, a prism shape, or the shape having a curved surface portion such as a lens can be used. It becomes the object of polishing using. Among these, it is particularly excellent for polishing a disk-shaped workpiece.

  The polishing composition of the present invention is suitably used for polishing precision component substrates. For example, it is suitable for polishing a magnetic disk medium such as a memory hard disk substrate, a magnetic recording medium substrate such as an optical disk and a magneto-optical disk, a precision component substrate such as a photomask substrate, an optical lens, an optical mirror, an optical prism, and a semiconductor substrate. Among them, the polishing composition of the present invention can remarkably reduce nano scratches that are important for high density and high integration, and is therefore suitable for polishing magnetic disks such as memory hard disk substrates and semiconductor substrates. It is particularly suitable for polishing a magnetic disk substrate.

  The polishing of the memory hard disk substrate and the semiconductor substrate is performed in a polishing process of a silicon wafer (bare wafer), a formation process of an embedded metal wiring, a planarization process of an interlayer insulating film, a formation process of an embedded metal wiring, an embedded capacitor formation process, and the like.

  As described above, nanoscratches can be reduced by using the polishing composition of the present invention. Specifically, the substrate was sandwiched by a polishing machine on which a nonwoven organic polymer polishing cloth or the like was attached, and the zeta potential of the abrasive was adjusted to -15 to 30 mV regardless of the method of blending the zeta potential adjuster. Examples include a method of polishing by supplying a polishing composition to the substrate surface and moving the polishing plate or the substrate while applying a constant pressure.

  The surface property of the substrate before being subjected to the polishing step using the polishing composition of the present invention is not particularly limited, but for example, a substrate having a surface property with an Ra of 1 nm is suitable.

  Further, the method for producing a substrate of the present invention is characterized by having a step of polishing using a polishing liquid composition in which the zeta potential of the abrasive is adjusted to -15 to 30 mV. The effect that the surface roughness of the subsequent workpiece is small and nano-scratch can be remarkably reduced is exhibited.

  The abrasive used in the method for producing a substrate of the present invention may be the same as that used in the polishing composition of the present invention.

  Among them, the average particle diameter of the primary particles of the abrasive is preferably 1 nm or more, more preferably 3 nm or more, further preferably 5 nm or more from the viewpoint of improving the polishing rate, and 40 nm from the viewpoint of reducing the surface roughness. Is preferably less than 35 nm, more preferably 35 nm or less, further preferably 30 nm or less, further preferably 25 nm or less, and further preferably 20 nm or less. Therefore, from the viewpoint of economically reducing the surface roughness, the average particle size of the primary particles is preferably 1 nm or more and less than 40 nm, more preferably 1 to 35 nm, still more preferably 3 to 30 nm, still more preferably 5 to 25 nm, More preferably, it is 5-20 nm. Furthermore, when primary particles are aggregated to form secondary particles, the average particle size of the secondary particles is preferably from the viewpoint of improving the polishing rate and reducing the surface roughness of the substrate. Is 5 to 150 nm, more preferably 5 to 100 nm, still more preferably 5 to 80 nm, still more preferably 5 to 50 nm, still more preferably 5 to 30 nm.

  The polishing step is preferably performed after the second step among the plurality of polishing steps, and particularly preferably performed in the final polishing step. At that time, in order to avoid mixing of the polishing material or polishing liquid composition in the previous process, different polishing machines may be used, and in the case of using different polishing machines, the substrate is removed at each stage. It is preferable to wash. The polishing machine is not particularly limited.

  The polishing composition of the present invention is particularly effective in the polishing process, but can be similarly applied to other polishing processes such as a lapping process.

  The substrate manufactured using the polishing composition of the present invention or the substrate manufacturing method of the present invention as described above is excellent in surface smoothness, for example, surface roughness (Ra) is 0.3 nm or less, preferably 0.2 nm or less, More preferably, 0.15 nm or less, More preferably, 0.13 nm or less is obtained.

Further, the manufactured substrate has very few nano scratches. Accordingly, when the substrate is, for example, a memory hard disk substrate, it can also cope with a recording density of 120 G / inch ² and further 160 G / inch ² , and when it is a semiconductor substrate, the wiring width 65 nm and even 45 nm can be supported.

  As a substrate to be polished, a Ni-P plated substrate was coarsely polished in advance with a polishing liquid containing an alumina abrasive to obtain an Ra of 1 nm, an aluminum alloy substrate having an outer periphery of 95 mmφ and an inner periphery of 25 mmφ. Polishing evaluation was performed.

Examples 1-9 and Comparative Examples 1-5 (however, Examples 8 and 9 are reference examples)
As shown in Table 1, as the abrasive, colloidal silica A (manufactured by DuPont, average particle size of primary particles 27 nm, D90 / D50 = 3.1), B (manufactured by DuPont, average particle size of primary particles 15 nm, D90 / D50 = 2.2), C (DuPont, average particle size of primary particles 19 nm, D90 / D50 = 1.6) or a mixture of A and B corresponding to Example 4 (DuPont, average particle size of primary particles) 18 nm, D90 / D50 = 3.0), 60% by weight of HEDP aqueous solution, 98% by weight sulfuric acid and / or citric acid as zeta potential adjusting agent, and 35% by weight as other components as required A polishing liquid composition having the composition, pH, and zeta potential of the abrasive shown in Table 1 was prepared using an aqueous hydrogen peroxide solution. The balance is ion exchange water.

  The order of mixing each component is that hydrogen peroxide is added to an aqueous solution of HEDP and sulfuric acid or citric acid diluted with water, and then the remaining components are added, mixed and adjusted, and then stirred. Were added little by little to the colloidal silica slurry.

  About the polishing liquid composition obtained in Examples 1-9 and Comparative Examples 1-5, zeta potential, nano scratch, and surface roughness (Ra) were measured and evaluated based on the following methods. The obtained results are shown in Table 1.

1. Polishing conditions / polishing tester: Speedfam, double-sided 9B polishing machine / polishing cloth: Fujibow, polishing pad (thickness 0.9 mm, hole diameter 30 μm, Shore A hardness 60 °)
・ Surface plate speed: 32.5r / min
Polishing liquid composition supply amount: 100 mL / min
Polishing time: 4 minutes Polishing load: 7.8 kPa
・ Number of loaded substrates: 10

2. Zeta potential measurement conditions and measurement equipment: “ELS-8000” (flat cell type) manufactured by Otsuka Electronics Co., Ltd.
・ Applied voltage: 80V
・ Measurement temperature: 25 ℃
・ Measurement sample: Using an aqueous solution of a zeta potential adjusting agent adjusted to the same pH as that of the polishing liquid composition (an aqueous solution comprising a zeta potential adjusting agent and water in the corresponding polishing liquid composition), the abrasive concentration is A polishing composition diluted to 0.05% by weight was prepared as a measurement sample.
-Number of measurements: The measurement was repeated three times under the same sample and the same measurement conditions, and the average of the three times was defined as the zeta potential.

3. Nano scratch measurement conditions / measurement equipment: “MicroMax VMX-2100CSP” manufactured by VISION PSYTEC
-Light source: 100% for both 2Sλ (250W) and 3Pλ (250W)
・ Chilled angle: -6 °
・ Magnification: Maximum (Field range: 1/120 of the total area)
・ Observation area: total area (substrate with outer circumference 95mmφ and inner circumference 25mm)
・ Iris: notch
・ Evaluation: Randomly select 4 out of the substrates put into the polishing tester, and divide the total number of nano scratches (on each side) of each of the 4 substrates by 8 to get The number of nano scratches was calculated. Moreover, the evaluation of the nanoscratches described in the table was performed by relative evaluation with respect to the number of nanoscratches (lines / surface) of Comparative Example 1.

4). Surface roughness (Ra) measurement conditions / measurement equipment: “NanoScope III, Dimension 3000”, manufactured by Digital Instruments
・ Scanrate: 1.0 Hz
・ Scanarea: 2 × 2 μm
Evaluation: The center between the inner periphery and the outer periphery was measured at 120 points every 120 °, and this was performed on both sides of the substrate to obtain an average value of a total of 6 points.

  From the results shown in Table 1, in the substrates obtained using the polishing liquid compositions of Examples 1 to 9, the generation of nanoscratches was suppressed and the surface roughness was lower than those of Comparative Examples 1 to 5. It can be seen that it is reduced.

  The polishing composition of the present invention is a precision component substrate, for example, a precision component such as a magnetic recording medium substrate such as a magnetic disk, an optical disk, or a magneto-optical disk, a photomask substrate, an optical lens, an optical mirror, an optical prism, or a semiconductor substrate. It is suitably used for polishing a substrate.

Claims (7)

An aluminum alloy substrate plated with Ni-P using a polishing composition having a pH of 1 to 4 comprising colloidal silica having an average primary particle size of 1 nm to 30 nm and a zeta potential adjuster . A method for reducing nanoscratches, comprising the step of adjusting the zeta potential of colloidal silica in the polishing composition to −10 to 10 mV, and reducing nanoscratches in a Ni—P plated aluminum alloy substrate . Zeta potential adjusting agent is an acid, a base, one or more selected from the group consisting of salts and surfactants, the process of claim 1. The method according to claim 1 or 2, wherein the polishing composition further comprises hydrogen peroxide . The method according to any one of claims 1 to 3, wherein the zeta potential regulator is one or more selected from nitric acid, sulfuric acid, phosphoric acid, citric acid and 1-hydroxyethylidene-1,1-diphosphonic acid. The method in any one of Claims 1-4 whose content of the zeta potential adjusting agent in polishing liquid composition is 0.05 to 15 weight%. The method according to claim 1, wherein the content of colloidal silica in the polishing composition is 1 to 15% by weight. The method in any one of Claims 1-6 whose D90 / D50 of colloidal silica is 1-5 .