Rinsing composition and method for polishing magnetic disk substrate

Abstract

To provide a rinsing agent composition capable of manufacturing a magnetic disk substrate in which a surface defect is not generated on a substrate surface and a scratch is not newly generated in a rinsing process.SOLUTION: A polishing agent composition includes at least (1) a step of supplying a polishing composition to a polishing machine to polish a magnetic disk substrate and (2) a step of rinsing the magnetic disk substrate obtained in the step (1), and is used in the step (2) in polishing of the magnetic disk substrate in which the steps (1) and (2) are performed by the same polishing machine, and contains a surfactant and water, in which the surfactant contains a repeating unit and a sulfonic acid (salt) And further has an aromatic group in the main chain of the repeating unit.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rinse composition and a method for polishing a magnetic disk substrate. More specifically, the present invention relates to a rinse composition used in polishing electronic components such as silicon semiconductors, compound semiconductors, SAW devices, and magnetic recording media such as hard disks, ceramic components made of oxide materials, and optical components such as glass lenses and plastic lenses, and a method for polishing a magnetic disk substrate comprising a rinsing step carried out using the rinse composition. More specifically, the present invention relates to a rinse composition used in finish polishing of a nickel-phosphorus-plated aluminum alloy substrate, and a method for polishing a magnetic disk substrate comprising a rinsing step carried out after finish polishing. [Background technology]

[0002] Conventionally, in the manufacturing process of various substrates, such as magnetic disk substrates and semiconductor substrates, which require highly accurate surface performance (surface properties), a polishing step is carried out using a polishing pad fixed to a polishing machine to polish and smooth the surface of the substrate to be polished.

[0003] In particular, in recent years, because it has become difficult to produce substrates with reduced surface roughness and scratches and pits to the required level within a specified polishing time, polishing methods using two or more polishing stages have been investigated. Specifically, a two-stage (multi-stage) polishing method is sometimes adopted in which the first stage (rough polishing) is performed primarily to remove relatively large waviness, large pits, and other surface defects from the substrate surface, and the second stage (finish polishing) removes small scratches and pits while achieving the required level of surface roughness.

[0004] However, if abrasive grains or polishing debris used in the first polishing step remain on the substrate obtained by the first polishing step, some of these may not be removed and remain in the second polishing step, causing defects. Furthermore, although most of these are removed in the second polishing step, some of the remaining abrasive grains and polishing debris remaining after the first polishing step may adversely affect the polishing performance of the second polishing step, inducing scratches and pits, which is not a desirable situation.

[0005] Furthermore, if residual abrasive grains or polishing debris from the second polishing step remain on the substrate surface, this may adversely affect the cleaning step or other steps carried out after the polishing step.

[0006] Therefore, to solve these problems, in a method for polishing a magnetic disk substrate using a multi-stage polishing method, it is necessary to completely remove residual abrasive grains and polishing debris from the substrate surface after the completion of each polishing step. Therefore, it is necessary to perform a rinsing process (rinsing step) on the substrate surface after each polishing step. Here, pure water, ultrapure water, distilled water, or the like containing no additives is generally used in the rinsing process.

[0007] Furthermore, in the final polishing step in the manufacturing process of magnetic disk substrates, i.e., the finish polishing step, acidic finish abrasive compositions containing colloidal silica abrasive grains are mainly used to satisfy the requirements of reducing surface roughness and scratches without reducing productivity. However, when a rinse treatment is performed with pure water after polishing using such an abrasive composition, there is a possibility that new scratches will be generated during the rinse step. Therefore, in order to solve this problem, attempts have been made to use a rinse agent containing surfactants or the like in addition to the above-mentioned pure water, etc.

[0008] For example, rinse compositions using a surfactant such as polystyrene sulfonic acid and an inorganic acid, an organic acid, and a salt (see Patent Document 1), rinse compositions using an oxoacid salt and a chloride (see Patent Document 2), and rinse compositions using hydrogen peroxide (see Patent Document 3) have been proposed. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-144193 [Patent Document 2] Japanese Patent Application Publication No. 10-152674 [Patent Document 3] Japanese Patent Application Laid-Open No. 2004-182800 Summary of the Invention [Problem to be solved by the invention]

[0010] However, in the case of the above-mentioned rinse agents, it is highly likely that they have not yet reached a fully satisfactory level in terms of reducing residual abrasive grains and polishing debris, and reducing new scratches that occur during the rinsing step, and so there remains a need for a rinse agent composition with excellent rinsing performance, as well as an improvement in a method for polishing a magnetic disk substrate using such a rinse agent composition.

[0011] In view of the above circumstances, an object of the present invention is to provide a rinse agent composition that can suppress or remove the generation of residual abrasive grains and polishing debris generated in each stage of the polishing process, thereby enabling the production of magnetic disk substrates that do not produce surface defects (scratches, pits) on the substrate surface and that do not generate new scratches during the rinsing process, and a method for polishing magnetic disk substrates using the rinse agent composition. [Means for solving the problem]

[0012] As a result of extensive research into the above-mentioned problems, the inventors of the present application have found that the above-mentioned problems can be solved by employing the following rinse agent composition and a method for polishing a magnetic disk substrate using the rinse agent composition.

[0013] [1] A rinse composition used in step (2) of polishing a magnetic disk substrate, the rinse composition comprising at least the following steps (1) to (2), wherein steps (1) and (2) are performed using the same polishing machine, the rinse composition comprising a surfactant and water, the surfactant being an anionic surfactant having a repeating unit and a sulfonic acid (salt) group in the molecule, and further having an aromatic group in the main chain of the repeating unit: (1) A step of supplying an abrasive composition to a polishing machine to polish a magnetic disk substrate. (2) A step of rinsing the magnetic disk substrate obtained in step (1).

[0014] [2] The rinse composition according to [1], wherein the anionic surfactant is at least one selected from the group consisting of naphthalenesulfonic acid compounds, ligninsulfonic acid compounds, aromatic aminosulfonic acid compounds, and salts thereof.

[0015] [3] The rinse composition according to [2], wherein the naphthalenesulfonic acid-based compound is at least one selected from the group consisting of naphthalenesulfonic acid formaldehyde condensates and methylnaphthalenesulfonic acid formaldehyde condensates.

[0016] [4] The rinse composition according to [1], wherein the polishing compound used in step (1) contains colloidal silica abrasive grains, a surfactant, and water, and the surfactant contained in the polishing compound composition is an anionic surfactant having a repeating unit and a sulfonic acid (salt) group in the molecule, and further having an aromatic group in the main chain of the repeating unit.

[0017] [5] A method for polishing a magnetic disk substrate, comprising at least the following steps (1) to (2), wherein steps (1) and (2) are performed using the same polishing machine to finish polish a nickel-phosphorus-plated aluminum alloy magnetic disk substrate, and wherein the rinse agent composition according to any one of the above items [1] to [4] is used in step (2). (1) A step of supplying an abrasive composition to a polishing machine to perform finish polishing of a nickel-phosphorus plated aluminum alloy magnetic disk substrate. (2) A step of rinsing the nickel-phosphorus plated aluminum alloy magnetic disk substrate obtained in step (1). [Effects of the Invention]

[0018] The rinse composition of the present invention is characterized by containing water and an anionic surfactant having a repeating unit and a sulfonic acid (salt) group in the molecule, and further having an aromatic group in the main chain of the repeating unit. By using the rinse composition in a method for polishing a magnetic disk substrate that includes a rinsing step, it is possible to remove abrasive grains and polishing debris generated during the polishing step and further reduce frictional resistance between the magnetic disk substrate and the polishing pad. As a result, it is possible to produce a substrate that is free of surface defects (scratches, pits) on the substrate surface and free of new scratches generated during the rinsing step. The method for polishing a magnetic disk substrate of the present invention can achieve the above-mentioned effects by using the rinse composition of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following describes embodiments of the present invention, but it should be understood that the present invention is not limited to the following embodiments, and that appropriate modifications and improvements to the following embodiments based on the ordinary knowledge of those skilled in the art, as long as they do not deviate from the spirit of the present invention, also fall within the scope of the present invention.

[0020] 1. Rinse aid composition The rinse agent composition of this embodiment is used for rinsing after polishing a magnetic disk substrate, and contains a surfactant and water.

[0021] 1-1.Surfactants The surfactant used in the rinse composition of this embodiment is an anionic surfactant having a repeating unit and a sulfonic acid (salt) group in the molecule, and further having an aromatic group in the main chain of the repeating unit. Specific examples include polyalkylarylsulfonic acid compounds such as naphthalenesulfonic acid formaldehyde condensates, methylnaphthalenesulfonic acid formaldehyde condensates, and anthracenesulfonic acid formaldehyde; melamine formalin resin sulfonic acid compounds such as melaminesulfonic acid formaldehyde condensates; ligninsulfonic acid compounds such as ligninsulfonic acid and modified ligninsulfonic acid; and aromatic aminosulfonic acid compounds such as aminoarylsulfonic acid-phenol-formaldehyde condensates.

[0022] In particular, among polyalkylarylsulfonic acid compounds, naphthalenesulfonic acid compounds such as naphthalenesulfonic acid formaldehyde condensates and methylnaphthalenesulfonic acid formaldehyde condensates, or ligninsulfonic acid compounds, aromatic aminosulfonic acid compounds, and salts thereof are particularly preferred.On the other hand, among naphthalenesulfonic acid compounds, naphthalenesulfonic acid formaldehyde condensates, methylnaphthalenesulfonic acid formaldehyde condensates, and salts thereof are particularly preferred.

[0023] As examples of the surfactants, the general formula of a naphthalenesulfonic acid formaldehyde condensate is shown in Chemical Formula 1, the general formula of an example of a ligninsulfonic acid compound is shown in Chemical Formula 2, and an example of an aromatic aminosulfonic acid compound, an aminobenzenesulfonic acid-phenol-formaldehyde condensate, is shown in Chemical Formula 3, each of which is shown as a chemical structural formula below (wherein, in Chemical Formulas 1 to 3, M represents hydrogen or a base).

[0024] [ka]

[0025] [ka]

[0026] [ka]

[0027] Furthermore, when each of them is a salt, examples of the counter ion include alkali metal salts such as sodium and potassium, alkaline earth metal salts such as calcium, ammonium salts, primary amine salts such as monoethanolamine, secondary amine salts such as diethanolamine, tertiary amine salts such as triethanolamine, and quaternary ammonium salts such as tetramethylammonium.

[0028] The content of the anionic surfactant in the rinse composition is preferably 0.0001 to 5.0% by mass, more preferably 0.001 to 3.0% by mass, and even more preferably 0.01 to 1.0% by mass. If the content is less than 0.0001% by mass, the effect of reducing residual abrasive grains and polishing debris on the substrate surface may be insufficient, and further, the frictional resistance between the substrate surface and the polishing pad may be difficult to reduce. On the other hand, if the content exceeds 5.0% by mass, the surfactant may remain on the polishing pad, carrier, and substrate surface, which may adversely affect subsequent processes. Furthermore, in the case of multiple polishing processes, the polishing resistance in the next batch of polishing processes may increase.

[0029] 1-2. Acids and / or their salts To further improve the rinsing effect, at least one member selected from the group consisting of inorganic acids, organic acids and salts thereof may be added to the rinse agent composition of the present invention.

[0030] Examples of inorganic acids include nitric acid, nitrous acid, sulfuric acid, hydrochloric acid, phosphoric acid, polyphosphoric acid, and molybdic acid. Examples of organic acids include carboxylic acids, sulfonic acids, aminocarboxylic acids, and organic phosphonic acids. Examples of carboxylic acids include glycolic acid, mercaptosuccinic acid, thioglycolic acid, lactic acid, malic acid, tartaric acid, citric acid, gluconic acid, glyceric acid, ascorbic acid, formic acid, acetic acid, propionic acid, butyric acid, hexanoic acid, and heptanoic acid. Examples of sulfonic acids include methanesulfonic acid, ethanesulfonic acid, and sulfosuccinic acid. Examples of aminocarboxylic acids include nitrilotriacetic acid, ethylenediaminetetraacetic acid, and dicarboxymethylglutamic acid. Examples of organic phosphonic acids include 1-hydroxyethylidene-1,1-diphosphonic acid.

[0031] Specific examples of salts of these acids include aluminum nitrate, nickel nitrate, lithium nitrate, sodium nitrate, potassium nitrate, sodium nitrite, potassium nitrite, aluminum sulfate, nickel sulfate, lithium sulfate, sodium sulfate, ammonium sulfate, aluminum chloride, ammonium chloride, sodium molybdate, and ammonium molybdate.

[0032] 1-3.Other ingredients The rinse agent composition of the present invention may contain an oxidizing agent such as hydrogen peroxide, if necessary. In addition, thickeners, dispersants, rust inhibitors, basic substances, etc. may also be added if necessary.

[0033] 1-4.Water The water in the rinse agent composition of the present invention is used as a medium, and examples thereof include distilled water, ion-exchanged water, and ultrapure water. From the viewpoint of surface cleanliness of the substrate to be rinsed, ion-exchanged water and ultrapure water are preferred, and ultrapure water is more preferred. The content of water in the rinse agent composition is preferably 60 to 99.9 mass%, more preferably 70 to 99.5 mass%. Furthermore, an organic solvent such as alcohol may be blended within a range that does not impair the effects of the present invention.

[0034] 1-5. pH of rinse aid composition The pH (25°C) of the rinse composition is preferably 1 to 12, for example, from the viewpoints of substrate rinsing properties, polishing machine corrosion prevention, and worker safety. When the substrate to be rinsed is a nickel-phosphorus-plated aluminum alloy substrate, the pH (25°C) is preferably 1 to 8.

[0035] 2. Abrasive composition The polishing agent composition used in the polishing step carried out prior to the rinsing step using the rinse agent composition of the present invention will be described below.

[0036] The abrasive composition described below is preferably an abrasive composition used in the finish polishing process of a magnetic disk substrate, and more preferably an abrasive composition used in the finish polishing process of a nickel-phosphorus plated aluminum alloy substrate.

[0037] 2-1.Abrasive grain The abrasive grains contained in the polishing agent composition used in the polishing step carried out prior to the rinsing step using the rinse agent composition of the present invention are preferably colloidal silica (colloidal silica abrasive grains).

[0038] The average particle size of the colloidal silica is preferably 1 to 50 nm, more preferably 5 to 40 nm. If the average particle size of the colloidal silica is less than 1 nm, it tends to aggregate and the stability of the dispersion state deteriorates. If the average particle size of the colloidal silica exceeds 50 nm, scratches on the substrate after polishing may worsen.

[0039] Colloidal silica is known to have various shapes, such as spherical, confetti-shaped (particles with multiple convex portions on the surface), and irregular shapes, and the primary particles are monodispersed in water to form a colloid. The colloidal silica used in the present invention is preferably spherical or nearly spherical. The use of spherical or nearly spherical colloidal silica can reduce scratches on the substrate after polishing.

[0040] Methods for producing colloidal silica include the water glass method, which uses alkali metal silicate such as sodium silicate or potassium silicate as a raw material and causes a condensation reaction of the raw material in an aqueous solution to grow particles; the alkoxysilane method, which uses tetraalkoxysilane such as tetraethoxysilane as a raw material and causes a condensation reaction of the raw material via hydrolysis with an acid or alkali in water containing a water-soluble organic solvent such as alcohol to grow particles; and a method of synthesizing silica particles by reacting metallic silicon with water in the presence of an alkali catalyst.

[0041] The concentration of colloidal silica in the polishing compound is preferably 1 to 50% by mass, and more preferably 2 to 30% by mass. If the concentration of colloidal silica in the polishing compound is less than 1% by mass, the removal rate may decrease. If the concentration of colloidal silica in the polishing compound exceeds 50% by mass, the colloidal silica may be more likely to gel.

[0042] 2-2.Surfactants The surfactant contained in the polishing composition used in the polishing step carried out prior to the rinsing step using the rinse composition of the present invention is an anionic surfactant having a repeating unit and a sulfonic acid (salt) group in the molecule and further having an aromatic group in the main chain of the repeating unit, and is at least one selected from the group consisting of naphthalenesulfonic acid compounds, ligninsulfonic acid compounds, aromatic aminosulfonic acid compounds, and salts thereof. Specific examples are given below.

[0043] Examples of suitable sulfonic acid compounds include polyalkylarylsulfonic acid compounds such as naphthalenesulfonic acid formaldehyde condensates, methylnaphthalenesulfonic acid formaldehyde condensates, and anthracenesulfonic acid formaldehyde; melamine formalin resin sulfonic acid compounds such as melamine sulfonic acid formaldehyde condensates; ligninsulfonic acid compounds such as ligninsulfonic acid and modified ligninsulfonic acid; and aromatic aminosulfonic acid compounds such as aminoarylsulfonic acid-phenol-formaldehyde condensates.

[0044] In particular, among polyalkylarylsulfonic acid compounds, naphthalenesulfonic acid compounds such as naphthalenesulfonic acid formaldehyde condensates and methylnaphthalenesulfonic acid formaldehyde condensates, or ligninsulfonic acid compounds, aromatic aminosulfonic acid compounds, and salts thereof are particularly preferred.Furthermore, among naphthalenesulfonic acid compounds, naphthalenesulfonic acid formaldehyde condensates, methylnaphthalenesulfonic acid formaldehyde condensates, and salts thereof are particularly preferred.

[0045] As examples of the above surfactants, the general formula of a naphthalenesulfonic acid formaldehyde condensate is shown in Chemical Formula 1, the general formula of an example of a ligninsulfonic acid compound is shown in Chemical Formula 2, and an example of an aromatic aminosulfonic acid compound, an aminobenzenesulfonic acid-phenol-formaldehyde condensate, is shown in Chemical Formula 3 (wherein, in Chemical Formulas 1 to 3, M represents hydrogen or a base).

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] Furthermore, when each of them is a salt, examples of the counter ion include alkali metal salts such as sodium and potassium, alkaline earth metal salts such as calcium, ammonium salts, primary amine salts such as monoethanolamine, secondary amine salts such as diethanolamine, tertiary amine salts such as triethanolamine, and quaternary ammonium salts such as tetramethylammonium.

[0050] The content of the anionic surfactant in the polishing compound is preferably 0.0001 to 5.0% by mass, more preferably 0.001 to 3.0% by mass, and even more preferably 0.01 to 1.0% by mass. If the content is less than 0.0001% by mass, the effect of reducing scratches on the substrate surface may be insufficient. If the content exceeds 5.0% by mass, the polishing rate may decrease and the scratch reduction effect may not be exerted.

[0051] 2-3. Oxidizing agents Examples of oxidizing agents contained in the polishing composition used in the polishing step carried out prior to the rinsing step using the rinse composition of the present invention include peroxides and nitrates, among which peroxides are preferred. Examples of peroxides include hydrogen peroxide, perborates, persulfates, among which hydrogen peroxide is preferred. The oxidizing agent has the effect of oxidizing the surface of the magnetic disk substrate, thereby accelerating polishing and thereby improving the polishing rate. The content of the oxidizing agent in the polishing composition is preferably 0.01 to 10% by mass. If the oxidizing agent content is less than 0.01% by mass, it is difficult to improve the polishing rate. On the other hand, if the oxidizing agent content exceeds 10% by mass, the surface of the magnetic disk substrate is likely to become rough.

[0052] 2-4. Acid The acid contained in the polishing composition used in the polishing step carried out prior to the rinsing step using the rinse composition of the present invention is preferably at least one of organic phosphonic acid and inorganic acid. Examples of organic phosphonic acids include 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), phosphonobutanetricarboxylic acid (PBTC), and aminotrismethylenephosphonic acid (NTMP). Examples of inorganic acids include phosphoric acid, sulfuric acid, phosphonic acid, nitric acid, and hydrochloric acid. Acids have the effect of chemically etching magnetic disk substrates, contributing to an improvement in the polishing rate.

[0053] The content of the acid in the polishing compound is preferably in the range of 0.1 to 8% by mass. If the content of the acid in the polishing compound is less than 0.1% by mass, the removal rate may not be improved. On the other hand, if the content of the acid in the polishing compound exceeds 8% by mass, the corrosive effect of the acid becomes strong, and the surface roughness of the substrate is likely to occur.

[0054] 2-5.Water The water contained in the polishing compound used in the polishing step carried out prior to the rinsing step using the rinse composition of the present invention is used as a medium, and examples thereof include ion-exchanged water, ultrapure water, and distilled water. Among these, ultrapure water is preferably used. The water content in the polishing compound is preferably 50 to 99% by mass, more preferably 60 to 98% by mass. In addition, an organic solvent such as alcohol may be added within a range that does not impair the effects of the present invention.

[0055] 2-6. pH of the polishing composition The pH (25°C) of the polishing composition used in the polishing step carried out prior to the rinsing step using the rinse composition of the present invention is preferably 0.1 to 4.0, more preferably 0.5 to 3.0. The polishing composition of the present invention is preferably used for the finish polishing of nickel-phosphorus plated aluminum alloy substrates. When the pH (25°C) is less than 4.0, the nickel-phosphorus plating film tends to dissolve, so by adjusting the pH (25°C) of the polishing composition to less than 4.0, the polishing rate can be improved. On the other hand, when the pH (25°C) of the polishing composition is less than 0.1, the etching action on the substrate surface becomes intense, which may worsen the surface roughness of the substrate after polishing.

[0056] 3.Method for polishing magnetic disk substrate The method for polishing a magnetic disk substrate to which the present invention is applicable is a method for polishing a magnetic disk substrate in which a rinsing step is carried out after the polishing step using the rinse agent composition of the present invention in the same polishing machine as the polishing step.

[0057] When the polishing step is performed in multiple stages, the rinsing step using the rinse composition of the present invention may be performed after the rough polishing step or after the finish polishing step, and the rinse composition of the present invention is preferably used in the rinsing step after the finish polishing step. The polishing machine is not particularly limited, and any known polishing machine for polishing magnetic disk substrates can be used.

[0058] A specific example of a method for polishing a magnetic disk substrate using the rinse composition of the present invention is a polishing method in which a magnetic disk substrate is sandwiched between plates to which polishing pads are attached, the plates and the magnetic disk substrate are moved while an abrasive composition is supplied, and then a rinsing step is performed by moving the plates and the magnetic disk substrate while the rinse composition of the present invention is supplied to a polishing machine. Generally, the rinsing step is performed for a shorter time and with a lower load than the polishing step. [Example]

[0059] The present invention will be described in more detail below with reference to examples, but is not limited to these examples. Table 1 shows the polishing results of Examples 1 to 4, in which a polishing agent composition not containing a surfactant was used in the finish polishing step of a magnetic disk substrate, and a rinse agent composition containing a surfactant of the present invention was used in the rinsing step, and Comparative Examples 1 to 4, in which a rinse agent composition not containing a surfactant of the present invention was used in the rinsing step.

[0060] In addition, the polishing results of Examples 5 to 7, in which an abrasive composition containing a surfactant was used in the finish polishing step of a magnetic disk substrate and then a rinse agent composition containing the surfactant of the present invention was used in the rinsing step, are shown in Table 1.

[0061] The surfactants used here are Labelin FM45 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), a sodium naphthalenesulfonate formaldehyde condensate, Sanex P252 (manufactured by Nippon Paper Industries Co., Ltd.), a sodium lignosulfonate, and Floric VP200 (manufactured by Floric Co., Ltd.), an aromatic aminosulfonic acid compound. Furthermore, Labelin FM45 is used as the surfactant contained in the abrasive composition.

[0062] [Table 1]

[0063] <1> Polishing conditions (finish polishing of magnetic disk substrate) Ten electroless nickel-phosphorus plated aluminum magnetic disk substrates with an outer diameter of 97 mm were roughly polished in one polishing run. When the abrasive composition and rinse composition were switched, the polishing pad was cleaned with a high-pressure washer, and then 10 dummy runs were carried out to familiarize the inside of the polishing machine before the test substrates for evaluation were loaded. Polishing machine: Speedfam Co., Ltd. 9B double-sided polishing machine Polishing pad: P2 pad manufactured by FILWEL Co., Ltd. Rotation speed of surface plate: Upper surface plate -15.0 rpm :Lower surface plate 20.0rpm Polishing pressure: 14kPa Polishing time: 5 minutes Abrasive compound supply rate: 70 ml / min

[0064] The abrasive composition used for polishing was prepared by adding 5.6 mass % colloidal silica with an average primary particle size of 21 nm, 0.8 mass % sulfuric acid, 0.6 mass % hydrogen peroxide, and a surfactant in amounts shown in Tables 1 and 2, and then adding pure water to make the total amount 100 mass %.

[0065] <2> Rinse conditions Immediately after the polishing step, a rinsing step was carried out using the same polishing machine under the following rinsing conditions. Polishing machine: Same as above Polishing pad: Same as above Platen rotation speed: Upper platen -15.0→0 rpm (slows down to a stop after 15 seconds of rinsing) Lower surface plate 20.0→0 rpm (slow down and stop after 15 seconds of rinsing) Rinse pressure: 2.0kPa Rinse time: 15 seconds Rinse agent composition supply rate: 2000ml / min The types and amounts of surfactants used as components other than pure water in the rinse agent compositions are shown in Table 1.

[0066] <3> Evaluation of polished magnetic disk substrates <3.1> Polishing speed The removal rate was calculated based on the following formula by measuring the mass of the aluminum disk lost after polishing. Polishing rate (μm / min) = mass loss of aluminum disc (g) / polishing time (min) / area of ​​one side of aluminum disc (cm 2 ) / density of electroless nickel-phosphorus plating film (g / cm 3 / 2×10 4 ) (However, in the above formula, the area of ​​one side of the aluminum disc is 69 cm 2 , the density of the electroless nickel-phosphorus plating film is 8.0 g / cm 3 )

[0067] <3.2> Scratch measurement conditions L scratches were measured using a full-surface substrate defect inspection machine (NS2000H, manufactured by Hitachi High-Tech Fine Systems Corporation). The numerical value is the total number of scratches detected on both sides of five of the ten substrates used in one polishing run (10 surfaces). Hi-Light 1, 2: 900V Scan Pitch: 3 μm Inner / Outer Radius:15.5-48.0mm Positive Level: 100mV Long Scratch Length:≧3000μm

[0068] <4> Consideration Examples 1 to 4, in which a polishing agent composition not containing a surfactant was used in the finish polishing step of a magnetic disk substrate and then a rinse agent composition containing a surfactant of the present invention was used in the rinsing step, showed fewer scratches than Comparative Example 1, in which a rinse agent composition not containing a surfactant was used in the rinsing step, and Comparative Examples 2 to 4, in which a surfactant different from the surfactant of the present invention was used.

[0069] In Example 6, in which an abrasive composition containing a surfactant was used in the finish polishing step of a magnetic disk substrate and then a rinse agent composition containing the surfactant of the present invention was used in the rinsing step, scratches were further reduced compared to Example 1.

[0070] Examples 5 and 7 are the results of Example 6 except that the content of the surfactant in the rinse agent composition was changed.

[0071] From the above, it is clear that the use of the rinse agent composition of the present invention has the effect of reducing scratches. [Industrial Applicability]

[0072] The rinse composition of the present invention can be used in the production of electronic components such as semiconductors and magnetic recording media such as hard disks. In particular, it can be used in a rinsing step after surface polishing of substrates for magnetic recording media such as glass magnetic disk substrates and aluminum magnetic disk substrates. Furthermore, it can be used in a rinsing step after surface polishing of aluminum substrates for magnetic recording media having an electroless nickel-phosphorus plating film formed on the surface of an aluminum alloy substrate.

Claims

1. A method for polishing a magnetic disk substrate, comprising at least the following steps (1) and (2), wherein the steps (1) and (2) are performed using the same polishing machine, comprising: A surfactant, Water and Contains The surfactant is A rinse agent composition comprising an anionic surfactant having a repeating unit and a sulfonic acid (salt) group in the molecule, and further having an aromatic group in the main chain of the repeating unit. (1) A step of supplying an abrasive composition to a polishing machine to polish a magnetic disk substrate. (2) A step of rinsing the magnetic disk substrate obtained in the step (1).

2. The anionic surfactant is 2. The rinse agent composition according to claim 1, wherein the rinse agent composition is at least one selected from the group consisting of naphthalenesulfonic acid compounds, ligninsulfonic acid compounds, aromatic aminosulfonic acid compounds, and salts thereof.

3. The naphthalene sulfonic acid compound is 3. The rinse agent composition according to claim 2, wherein the rinse agent is at least one selected from the group consisting of naphthalenesulfonic acid formaldehyde condensates and methylnaphthalenesulfonic acid formaldehyde condensates.

4. The abrasive composition used in the step (1) Colloidal silica abrasive grains; A surfactant, Water and Contains The surfactant contained in the polishing compound is 2. The rinse agent composition according to claim 1, which is an anionic surfactant having a repeating unit and a sulfonic acid (salt) group in the molecule, and further having an aromatic group in the main chain of the repeating unit.

5. A polishing method for a magnetic disk substrate, comprising at least the following steps (1) and (2), wherein steps (1) and (2) are performed using the same polishing machine in finish polishing of a nickel-phosphorus-plated aluminum alloy magnetic disk substrate, using the rinse composition according to any one of claims 1 to 4, which is used in step (2): (1) A step of supplying an abrasive composition to a polishing machine to perform finish polishing of a nickel-phosphorus plated aluminum alloy magnetic disk substrate. (2) A step of rinsing the nickel-phosphorus plated aluminum alloy magnetic disk substrate obtained in step (1).

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