JP4214107B2 - Polishing liquid composition - Google Patents

Description

  The present invention relates to a polishing liquid composition, an abrasive particle preparation liquid used for preparing the polishing liquid composition, and a method for producing a substrate using the polishing liquid composition.

  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. Along with this, the surface quality required after polishing in the manufacturing process of the magnetic disk substrate is becoming stricter year by year. That is, it is necessary to reduce the surface roughness, micro waviness, roll-off and protrusions according to the low flying height of the head, and the allowable number of scratches per substrate surface is small according to the decrease in the unit recording area, Its size and depth are getting smaller and 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 when exposing to a photoresist becomes shallow, and further surface smoothness is desired.
In response to such demands, for the purpose of improving the surface smoothness, a polishing slurry having a reduced number of coarse particles has been proposed in order to reduce scratches (such as scratches) generated on the surface of the object to be polished ( Patent Documents 1 to 3).
Japanese Unexamined Patent Publication No. 2000-15560 JP 2001-271058 A Japanese Patent Laid-Open No. 2003-188122

  An object of the present invention is to provide a polishing composition that has a small surface roughness of an object to be polished after polishing, significantly reduces nanoscratches that are important in densification, and can be polished economically. And a method for producing a substrate having a step of using a polishing particle preparation liquid used to prepare the polishing liquid composition, and the polishing liquid composition.

That is, the gist of the present invention is as follows.
[1] A polishing composition that contains colloidal silica having an average primary particle diameter of 1 to 50 nm and water, satisfying the following conditions, and having a pH of 0.1 to 4 :
(1) Colloidal silica of 0.56 μm or more and less than 1 μm is less than 100,000 per 1 cm ^{3 of the} polishing composition, and (2) 1 μm or more of colloidal silica is 0 with respect to all the colloidal silica in the polishing composition. 0.001% by weight or less,
[2] A polishing particle preparation liquid containing colloidal silica having an average primary particle diameter of 1 to 50 nm and water satisfying the following conditions, and having a pH of 0.1 to 4 : Abrasive particle preparation solution used for:
(I) Colloidal silica of 0.56 μm or more and less than 1 μm is not more than 100000 per 1 cm ^{3 of the} abrasive particle preparation liquid, and (ii) 0 μm or more of colloidal silica is 0 with respect to all the colloidal silica in the abrasive particle preparation liquid. 0.001% by weight or less,
[3] The present invention relates to a method for producing a substrate, comprising a step of polishing the substrate using the polishing composition according to [1].

  The polishing liquid composition of the present invention is used, for example, in a polishing process for a substrate for precision parts for high density or high integration, thereby realizing an economical polishing rate and excellent surface smoothness of the substrate after polishing. In addition, since fine nano scratches can be remarkably reduced, it is possible to produce high-quality magnetic disk substrates having excellent surface properties and substrates for precision components such as semiconductor element substrates.

The polishing liquid composition of the present invention contains an abrasive and water, has a pH of 0.1 to 7, and (1) abrasive particles of 0.56 μm or more and less than 1 μm are 500,000 per 1 cm ^{3 of the} polishing liquid composition. 000 particles or less, and (2) 1 μm or more of abrasive particles are 0.001% by weight or less based on the total abrasive particles in the polishing composition, and significantly reduce nano scratches that cause defects It is possible to provide a substrate having excellent surface smoothness at an economical polishing rate. This nano-scratch is a physical property that is important for high density or high integration particularly in a magnetic disk substrate or a semiconductor element substrate. Therefore, by using the polishing composition of the present invention, a high-quality magnetic disk substrate or semiconductor element substrate having excellent surface properties can be produced.

  The nano-scratch in the present invention is a fine flaw on the substrate surface having a depth of 10 nm or more and 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). It can be quantitatively evaluated by the number of nano scratches by measurement with “MicroMax” manufactured by VISION PSYTEC, which is a visual inspection apparatus described in the examples described later.

  The nano scratch is a surface defect that has not been detected conventionally. That is, when a conventionally known method is used, the quality of the substrate is insufficient for higher density such as higher capacity and higher integration. As a result of intensive studies by the inventors of the present invention, it has been found for the first time that the reduction of “nano scratches” that could not be detected has been insufficient.

  Although the mechanism for reducing nanoscratches in the present invention is not clear, aggregates of abrasive primary particles or coarse abrasive primary particles contained in the polishing liquid composition are subjected to a local load under the polishing pressure and contact the surface of the object to be polished. It is thought that deep nanoscratches are occurring. It has been clarified that the number of particles affects the submicron-order particles because they are scratched by single particles or aggregates, and the larger the size of the micron-order particles, the more easily the scratches are generated. In the present specification, the abrasive particles in the polishing liquid composition include not only primary particles but also aggregated particles obtained by aggregating primary particles.

The number of abrasive particles of 0.56 μm or more and less than 1 μm in the polishing liquid composition is 500,000 or less per 1 cm ^{3 of the} polishing liquid composition, and from the viewpoint of reducing nanoscratches, preferably 400,000 or less, more preferably 300,000 or less, more preferably 200,000 or less, more preferably 100,000 or less.

  Further, the amount of abrasive particles of 1 μm or more with respect to all abrasive particles in the polishing composition is 0.001% by weight or less, and from the viewpoint of reducing nanoscratches, preferably 0.0008% by weight or less, more preferably 0. .0007% by weight or less, more preferably 0.0006% by weight or less, and still more preferably 0.0005% by weight or less.

  Further, the abrasive particles having a size of 3 μm or more with respect to all the abrasive particles in the polishing composition are, for example, 0.0008% by weight or less, preferably 0.0007% by weight or less, more preferably 0.000% by weight or less from the viewpoint of reducing nanoscratches. It is 0006% by weight or less, more preferably 0.0005% by weight or less, and further preferably 0.0004% by weight or less.

  The polishing particle diameter in the polishing composition can be determined by a number counting system (Sizing Particle Optical Sensing method), for example, “Accumizer 780” and Coulter (Culter) manufactured by Particle Sizing Systems, USA. ) It can be measured by “Coulter Counter” manufactured by the company.

  There is no limitation on the method of controlling the number of abrasive particles of 0.56 μm or more and less than 1 μm, and the content of abrasive particles of 1 μm or more, and even 3 μm or more, but the general dispersion or A particle removal method can be used. For example, a dispersion method using a high-pressure dispersion device such as a high-speed dispersion device or a high-pressure homogenizer, a sedimentation method using a centrifugal separator or the like, and a filtration method such as microfiltration or ultrafiltration using a filter medium can be used. When processing using these, each may be processed independently or may be processed in combination of two or more, and there is no limitation on the processing order of the combination. Further, the processing conditions and the number of processing times can be appropriately selected and used.

  Among these, as a method for efficiently and economically removing the aggregates of abrasive primary particles or coarse abrasive primary particles contained in the polishing composition, microfiltration with a filter is preferably used.

  A depth type filter or a pleat type filter can be used as a filtering material for microfiltration. As the depth type filter, a filter of a bag type (manufactured by Sumitomo 3M Co., Ltd.) or a cartridge type (manufactured by Advantech Toyo Co., Ltd., Nippon Pole Co., CUNO Co., Ltd., Daiwabo Co., Ltd.) can be used.

  The depth type filter is characterized in that the pore structure of the filter medium is rough at the inlet, finer at the outlet side, and finer continuously or stepwise from the inlet side toward the outlet side. That is, among coarse particles, large particles are collected near the inlet side, and small particles are collected near the outlet side. Further, coarse particles are easily removed because they are collected in multiple stages in the thickness direction of the filter. The shape of the depth filter may be a bag-like bag type or a hollow cylindrical cartridge type.

A pleated filter is a hollow cylindrical cartridge type formed by filtering a filtering material into a pleat shape. Unlike depth-type filters that collect in each part in the thickness direction, pleated filters are said to be mainly collected on the filter surface because the filter material is thin and generally has high filtration accuracy. It is a feature.
As the filter medium, a filter having an intermediate structure between a depth type and a pleat type can also be used.

  The filtration method may be a circulation type that repeatedly filters or a one-pass method. Alternatively, a batch method that repeats the one-pass method may be used. As the liquid passing method, a pump is preferably used in the circulation type in order to pressurize, and in addition to using the pump in the one-pass method, a pressure filtration method in which air pressure or the like is introduced into the tank can be used.

By appropriately selecting the pore structure of the filter, the particle size of the coarse particles to be removed can be controlled.
The filter system may be single-stage filtration or multistage filtration by combination. For multi-stage filtration, the filter pore size and filter material structure are selected appropriately, and the filter processing order is selected appropriately to improve the particle size control (filtration accuracy) and economic efficiency of the coarse particles to be removed. There is an effect that can be done. That is, when a filter having a large pore structure is used in the former stage and a fine filter is used in the latter stage, there is an effect that the lifetime of the filter can be extended as a whole. In the structure of the filter medium, if the depth type is used at the front stage and the pleat type is used at the rear stage, there is an effect that the life of the filter can be extended as a whole.

  As the abrasive used in the present invention, abrasives generally used for polishing can be used, including metal, metal or metalloid carbide, nitride, oxide, boride, diamond. Etc. 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 (hereinafter referred to as ceria). ), Zirconium oxide and the like, and the use of one or more of these is preferable from the viewpoint of improving the polishing rate. Among them, silica, alumina, titanium oxide, ceria, zirconium oxide, and the like are suitable for polishing precision component substrates such as semiconductor element substrates and magnetic disk substrates.

  Abrasive particles are preferably colloidal particles and fumed particles from the viewpoint of reducing nano-scratches that cause surface defects, among which colloidal particles are preferable, and examples thereof include colloidal silica particles, colloidal ceria particles, and colloidal alumina particles. More suitable. The colloidal silica particles can be obtained, for example, by a production method in which the colloidal silica particles are generated from a silicic acid aqueous solution. In addition, those obtained by surface modification or surface modification of these abrasive particles with functional groups, those obtained by compounding with surfactants or other abrasives, and the like can also be used.

  The average particle size of the primary particles of the abrasive is preferably 1 to 50 nm from the viewpoint of reducing nanoscratches and the surface roughness (centerline average roughness: Ra, Peak to Valley value: Rmax). From the viewpoint of simultaneously improving the polishing rate, the thickness is more preferably 3 to 50 nm, further preferably 5 to 40 nm, and further preferably 5 to 30 nm.

  The average particle size of the primary particles of the abrasive can be obtained as an average particle size when measured by each method by a method obtained from an observation image with a transmission electron microscope (TEM), a titration method, or a BET method. .

  The content of the abrasive in the polishing composition at the time of use is preferably 0.5% by weight or more, more preferably 1% by weight or more, further preferably 3% by weight or more, from the viewpoint of improving the polishing rate. From the viewpoint of economically improving the surface quality, it is preferably 20% by weight or less, more preferably 15% by weight or less, 13% by weight or less, and further preferably 10% by weight or less. is there. Therefore, from the viewpoint of improving the polishing rate and economically improving the surface quality, the content is preferably 0.5 to 20% by weight, more preferably 1 to 15% by weight, and further preferably 3 to 13% by weight. %, More preferably 5 to 10% by weight. The content of the abrasive may be either the content at the time of producing the polishing liquid composition or the content at the time of use. Usually, it is produced as a concentrated solution, and this is often used after being diluted. .

  Examples of water used in the present invention include ion exchange water, distilled water, and ultrapure water. The water content corresponds to the balance obtained by removing the abrasive and other components from 100% by weight, preferably 60 to 99% by weight, and more preferably 80 to 97% by weight.

  The pH of the polishing composition of the present invention is 0.1-7. In the alkalinity, the generation of nanoscratches is remarkable compared to the acidity. The generation mechanism is not clear, but in an alkaline atmosphere in which abrasive particles repel each other due to surface charges, aggregates of abrasive primary particles or coarse abrasive primary particles contained in the polishing composition are dense in the polishing part. It is presumed that it is not possible to perform proper filling and is likely to receive a local load under the polishing pressure. The pH is preferably determined according to the type of the object to be polished and the required characteristics. When the material of the object to be polished is a metal material, the pH is preferably 6 or less, more preferably 5 from the viewpoint of improving the polishing rate. Hereinafter, it is more preferably 4 or less. Further, from the viewpoint of the influence on the human body and the prevention of corrosion of the polishing apparatus, the pH is preferably 0.5 or more, more preferably 1 or more, and further preferably 1.4 or more. In particular, in the case of a precision component substrate whose material to be polished is a metal material, such as a nickel-phosphorus (Ni-P) plated aluminum alloy substrate, the pH is 0.5 to 6 in consideration of the above viewpoint. More preferably, it is 1.0-5, More preferably, it is 1.4-4.

  The pH can be adjusted with the following acids and salts. Specifically, inorganic acids such as nitric acid, sulfuric acid, nitrous acid, persulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, phosphonic acid, phosphinic acid, pyrophosphoric acid, tripolyphosphoric acid, amidosulfuric acid, or salts thereof, 2-amino Ethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane- 1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2- Diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane- , 3,4-tricarboxylic acid, organic phosphonic acids such as α-methylphosphonosuccinic acid or their salts, aminocarboxylic acids such as glutamic acid, picolinic acid, aspartic acid or their salts, oxalic acid, nitroacetic acid, maleic acid And carboxylic acids such as oxaloacetic acid or salts thereof. Of these, inorganic acids or organic phosphonic acids and their salts are preferred from the viewpoint of reducing nanoscratches.

  Among inorganic acids or salts thereof, nitric acid, sulfuric acid, hydrochloric acid, perchloric acid or salts thereof are more preferable. Among organic phosphonic acids or salts thereof, 1-hydroxyethylidene-1,1-diphosphone is preferred. More preferred are acids, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) or salts thereof. These acids or their salts may be used alone or in admixture of two or more.

  The counter ion (cation) of these salts is not particularly limited, and specific examples include salts with metal ions, ammonium ions, and alkylammonium ions. Specific examples of the metal include metals belonging to 1A, 1B, 2A, 2B, 3A, 3B, 4A, 6A, 7A, or Group 8 of the periodic table (long period type). From the viewpoint of reducing nanoscratches, ammonium ions or metal ions belonging to Group 1A are preferred.

  Moreover, other components can be mix | blended with the polishing liquid composition of this invention as needed. For example, a thickener, a dispersant, a rust inhibitor, a basic substance, a surfactant, and the like can be given. Moreover, although it cannot generally limit by the material of to-be-polished material, generally an oxidizing agent can be added with a metal material from a viewpoint of improving a grinding | polishing rate. Examples of the oxidizing agent include hydrogen peroxide, permanganic acid, chromic acid, nitric acid, peroxo acid, oxyacid, or salts thereof and oxidizing metal salts.

  The polishing composition of the present invention having the above-described configuration can be prepared by mixing the above-described components by a known method.

Examples of the method for preparing the polishing composition include the following two methods.
(1) A method of adding other components to a mixture of an abrasive particle preparation solution and water, and (2) a method of adding an abrasive particle preparation solution to a mixture of other components and water.

Among these, from the economical point of view, the following conditions are used as a concentrate:
(I) 0.56 μm or more and less than 1 μm of abrasive particles are 500,000 or less per 1 cm ^{3 of the} abrasive particle preparation liquid, and (ii) 1 μm or more of abrasive particles are 0.1% relative to all abrasive particles in the abrasive particle preparation liquid. An abrasive particle preparation liquid (Aspect A-1) containing an abrasive satisfying 001% by weight or less and water is prepared, and then, the abrasive particle preparation liquid is blended with other components as described above. It is preferable to prepare a polishing liquid composition.
Further, from the viewpoint of the dispersion stability of the abrasive, the method (2) in which the abrasive particle preparation liquid (Aspect A-1) is added to a mixture of other components and water is preferable.
In the method (1), other components can be diluted with an appropriate amount of water as necessary.
Accordingly, the present invention also relates to an abrasive particle preparation solution.

The abrasive particle preparation liquid may be any liquid used in the above-described method (1) or (2) for preparing the polishing liquid composition. Examples of the abrasive particle preparation liquid include the following aspects other than the aspect A-1. It is done.
(Aspect A-2) Furthermore, the abrasive particle preparation liquid of aspect A-1 that satisfies the following conditions:
(Iii) The abrasive particles of 3 μm or more are 0.0008% by weight or less based on the total abrasive particles in the abrasive particle preparation liquid;
(Aspect A-3) Abrasive particle preparation liquid according to aspect A-1 or A-2, in which the average primary particle diameter of the abrasive is 1 to 50 nm;
(Aspect A-4) Abrasive particle preparation liquid according to aspects A-1 to A-3, in which the content of the abrasive in the abrasive particle preparation liquid is 1 to 60% by weight;
(Aspect A-5) Abrasive particle preparation liquid according to Aspects A-1 to A-4, in which the abrasive is colloidal silica;
(Aspect A-6) The abrasive particle preparation liquid according to aspects A-1 to A-5, which is used to prepare a polishing liquid composition for a magnetic disk substrate.

The content of the abrasive in the abrasive particle preparation liquid is preferably 1% by weight or more, more preferably 5% by weight or more, and still more preferably 10% by weight or more from the viewpoint of improving the polishing rate. From the viewpoint of improving surface quality, it is preferably 60% by weight or less, more preferably 50% by weight or less. Accordingly, the content is preferably 1 to 60% by weight, more preferably 5 to 50% by weight, and still more preferably 10 to 50% by weight.
Further, the water content in the abrasive particle preparation liquid is preferably 40% by weight or more, more preferably 50% by weight or more from the viewpoint of fluidity of the abrasive particle preparation liquid, and also improves the polishing rate. From the viewpoint, it is preferably 99% by weight or less, more preferably 95% by weight or less, and still more preferably 90% by weight or less. Therefore, the content is preferably 40 to 99% by weight, more preferably 50 to 95% by weight, and still more preferably 50 to 90% by weight.

The abrasive particle preparation liquid can be suitably used, for example, for preparing the polishing liquid compositions of the following embodiments 1 to 6.
(Aspect 1) A polishing composition that contains an abrasive and water and satisfies the following conditions and has a pH of 0.1 to 7:
(1) 500,000 or less of abrasive particles of 0.56 μm or more and less than 1 μm per 1 cm ^{3 of the} polishing liquid composition, and (2) 0. 1 μm or more of polishing particles with respect to all polishing particles in the polishing liquid composition. 001 wt% or less;
(Aspect 2) Furthermore, the polishing composition of aspect 1 satisfying the following conditions:
(3) The abrasive particles of 3 μm or more are 0.0008% by weight or less based on the total abrasive particles in the polishing liquid composition;
(Aspect 3) The polishing composition according to aspect 1 or 2, wherein the average primary particle diameter of the abrasive is 1 to 50 nm;
(Aspect 4) The polishing liquid composition according to aspects 1 to 3, wherein the content of the abrasive in the polishing liquid composition is 0.5 to 20% by weight;
(Aspect 5) The polishing composition according to aspects 1 to 4, wherein the abrasive is colloidal silica;
(Aspect 6) The polishing liquid composition according to aspects 1 to 5 used for a magnetic disk substrate.

  The polishing liquid composition of the present invention is supplied, for example, between a non-woven organic polymer polishing cloth or the like (polishing pad) and a substrate to be polished, that is, a polishing disk in which the polishing liquid composition is attached to the polishing pad. Is supplied to the polishing surface of the substrate sandwiched in step, and is used for the polishing step while contacting the substrate by moving the polishing disk and / or the substrate under a predetermined pressure. This polishing can remarkably suppress the generation of nanoscratches.

  In order to effectively reduce nano scratches, a polishing liquid composition is prepared by using the polishing liquid composition of the present invention or by mixing each component so as to be the composition of the polishing liquid composition of the present invention. The substrate to be polished is polished. Thereby, the surface defect of a to-be-polished substrate, especially nano scratch can be remarkably reduced, and a substrate excellent in surface quality with low surface roughness can be manufactured.

  It is particularly suitable for manufacturing precision component substrates. For example, it is suitable for polishing precision component substrates such as magnetic disk substrates such as magnetic disks, magneto-optical disks, and optical disks, photomask substrates, optical lenses, optical mirrors, optical prisms, and semiconductor substrates. In the manufacture of a semiconductor substrate, the polishing liquid of the present invention is used in a polishing process of a silicon wafer (bare wafer), a formation process of an embedded element isolation film, a planarization process of an interlayer insulating film, a formation process of an embedded metal wiring, a formation process of an embedded capacitor, etc. Compositions can be used.

  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 material of the object to be polished is preferably a polishing liquid composition of the present invention, for example, metal or semimetal such as silicon, aluminum, nickel, tungsten, copper, tantalum, titanium, or alloys thereof, glass, glassy carbon, Examples thereof include glassy substances such as amorphous carbon, ceramic materials such as alumina, silicon dioxide, silicon nitride, tantalum nitride, and titanium carbide, and resins such as polyimide resin. 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.

  There is no particular limitation on the shape of the object to be polished. For example, the polishing liquid composition of the present invention has a shape having a flat portion such as a disk shape, a plate shape, a slab shape, a prism shape, or a shape having a curved surface portion such as a lens. Things are used. Among them, it is excellent for polishing a disk-shaped workpiece.

  The surface roughness, which is a measure of surface smoothness, is not limited in its evaluation method, but for example, it is evaluated as a roughness that can be measured at a short wavelength of 10 μm or less in an atomic force microscope (AFM), and the center line average It can be expressed as roughness Ra (AFM-Ra). The polishing composition of the present invention is suitable for a polishing process for a magnetic disk substrate, and further for a polishing process for reducing the surface roughness (AFM-Ra) of the substrate after polishing to 2.0 mm or less.

  In the substrate manufacturing process, when there are a plurality of polishing processes, it is preferable that the polishing composition of the present invention is used in the second and subsequent processes, which significantly reduces nanoscratches and surface roughness, and has excellent surface smoothness. From the viewpoint of obtaining the above, it is particularly preferred to be used in the finish polishing step. The finish polishing process refers to at least one final polishing process when there are a plurality of polishing processes.

  At that time, in order to avoid mixing of the polishing material and polishing liquid composition in the previous process, different polishing machines may be used, and when different polishing machines are used, a substrate is provided for each process. It is preferable to wash. The polishing machine is not particularly limited. The substrate manufactured in this way has nano scratches remarkably reduced and is excellent in surface smoothness. That is, the surface roughness after polishing (AFM-Ra) is, for example, 2.0 mm or less, preferably 1.8 mm or less, more preferably 1.5 mm or less.

  The surface properties of the substrate before being subjected to the polishing step using the polishing liquid composition of the present invention are not particularly limited. For example, a substrate having a surface property with an AFM-Ra of 10 mm or less is suitable.

  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. The polishing step is preferably performed after the second step among the plurality of polishing steps, and particularly preferably performed in the finish polishing step.

  As described above, the substrate manufactured using the polishing composition of the present invention or the substrate manufacturing method of the present invention is excellent in surface smoothness and has a surface roughness (AFM-Ra) of, for example, 2.0 mm or less. Preferably, it is 1.8 mm or less, more preferably 1.5 cm or less.

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

  As a substrate to be polished, an aluminum alloy substrate plated with Ni-P having an outer diameter of 95 mmφ and an inner diameter of 25 mmφ having a thickness of 1.27 mm, which was coarsely polished in advance with a polishing liquid containing an alumina abrasive, was used. Polishing evaluation was performed.

Example 1
As an abrasive, 25 L of colloidal silica slurry (manufactured by DuPont, average particle size of primary particles 22 nm, silica particle concentration 40% by weight) is filtered with a bag-type depth filter (manufactured by Sumitomo 3M, liquid filter 522). Next, the mixture was filtered through a pleated filter (Advantech Toyo Co., Ltd., TCS-E045-S1FE) to obtain an abrasive particle preparation liquid a in Table 1 (Preparation Example 1). A predetermined amount of 35% by weight of hydrogen peroxide water (manufactured by Asahi Denka Kogyo Co., Ltd.) and 60% by weight of HEDP (1-hydroxyethylidene-1,1-diphosphonic acid) in ion-exchanged water so as to have the concentrations shown in Table 2 ) Aqueous solution (manufactured by Solusia Japan) and 95% by weight sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were added. Obtained.

Example 2
Abrasive particle preparation liquid b (Preparation Example 2) and a polishing liquid composition B shown in Table 1 were obtained in the same manner as in Example 1 except that HDCII (MCY1001J012H13) manufactured by Nippon Pole Co., Ltd. was used for the pleated filter.

Example 3
Abrasive particle preparation liquid c (Preparation Example 3) and a polishing liquid composition C shown in Table 1 were obtained in the same manner as in Example 1 except that ZENOpore (70006-01N-120PG) manufactured by CUNO was used for the pleated filter. .

Example 4
The same procedure as in Example 1 was conducted except that the pleated filter was changed to Advantech Toyo Co., Ltd. (TCPD-05A-S1FE), and abrasive particle preparation liquid d (Preparation Example 4) and polishing liquid composition D in Table 1 were obtained. .

Example 5
A predetermined amount of a 60% by weight HEDP aqueous solution and 95% by weight sulfuric acid were added to ion-exchanged water. While stirring the mixed aqueous solution, the abrasive particle preparation liquid a of Preparation Example 1 was added to prepare a polishing liquid composition E. Obtained.

Example 6
Abrasive particle preparation liquid g (Preparation Example 5) and polishing liquid composition G shown in Table 1 were carried out in the same manner as in Example 1 except that the pleated filter was changed to an intermediate structure Ultipleat profile (PUY1UY020H13) manufactured by Nippon Pole. Got.

Example 7 (Reference Example)
A predetermined amount of 35% by weight hydrogen peroxide solution, 60% by weight HEDP aqueous solution and 95% by weight sulfuric acid were added to ion-exchanged water, and the abrasive particle preparation solution a of Preparation Example 1 was added while stirring the mixed aqueous solution. A polishing liquid composition I was obtained.

Example 8
A diluted slurry was prepared by adding 86% of ion-exchanged water necessary for the concentrations shown in Table 2 to the abrasive particle preparation liquid a of Preparation Example 1. Separately, in the remaining 14% of the ion-exchanged water, a predetermined amount of 35% by weight of hydrogen peroxide (Asahi Denka Kogyo Co., Ltd.) and 60% by weight of HEDP (1-hydroxyethylidene-1,1-diphosphonic acid) An acid aqueous solution in which an aqueous solution (manufactured by Solusia Japan) and 95% by weight sulfuric acid (manufactured by Wako Pure Chemical Industries, Ltd.) were mixed was prepared. This aqueous acid solution was added to the diluted slurry with stirring to obtain a polishing composition K.

Comparative Example 1
Abrasive particle preparation liquid f (Preparation Example 6) and a polishing liquid composition shown in Table 1 except that Daiwabo's Wave Star (W-004-S-DO-E) was used for the pleated filter. Product F was obtained.

Comparative Example 2
Under stirring of ion-exchanged water, the abrasive particle preparation liquid a of Preparation Example 1 was added so as to have the concentration shown in Table 2, and a polishing liquid composition H was obtained.

Comparative Example 3
Under stirring of ion exchange water, colloidal silica slurry (manufactured by Nissan Chemical Industries, Snowtex ST-50, average particle size 30 nm, silica particle concentration 48% by weight) is used as an abrasive so as to have the concentration shown in Table 2. Further, the mixture was suction filtered through a membrane filter (diameter 90 mm) made of 0.45 μm cellulose acetate to obtain a polishing composition J.
About the polishing particle preparation liquid and polishing liquid composition obtained in Examples 1-8 and Comparative Examples 1-3, coarse particles and nanoscratches were measured and evaluated based on the following methods. The obtained results are shown in Table 2.

1. Polishing conditions / polishing tester: Speedfam, double-sided 9B polisher / polishing pad: Fujibow, urethane finish polishing pad / upper plate rotation speed: 32.5 r / min
Polishing liquid composition supply amount: 100 mL / min
・ Main polishing time: 4 min
-Final polishing load: 7.8 kPa
・ Number of loaded substrates: 10

2. Measuring conditions and measuring equipment for abrasive particles: “Accurizer 780APS” manufactured by PSS
・ Injection Loop Volume: 1ml
・ Flow Rate: 60mL / min
・ Data Collection Time: 60sec
・ Number Channels: 128

3. Nano scratch measurement conditions / measurement equipment: “MicroMax VMX-2100CSP” manufactured by VISION PSYTEC
-Light source: 100% for both 2Sλ (250W) and 3Pλ (250W)
-Tilt angle: -6 °
・ Magnification: Maximum (Field range: 1/120 of the total area)
・ Observation area: total area (substrate with outer diameter 95mmφ and inner diameter 25mmφ)
・ 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 Table 2 was performed by relative evaluation with respect to the number of nanoscratches (lines / surface) of Comparative Example 1.

[Polishing speed measurement conditions]
Dividing the weight difference (g) of the object before and after polishing by the density (8.4 g / cm ³ ) of the object to be polished, the surface area (65.97 cm ² ) of the object to be polished, and the polishing time (min), unit The polishing amount per hour was calculated as the polishing rate (μm / min).

[Evaluation method of surface roughness (AFM-Ra)]
Measuring instrument: “TM-M5E” manufactured by Veeco
・ Mode: non-contact
・ Scanrate: 1.0 Hz
・ Scanarea: 10 × 10 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 2, the substrates obtained using the polishing liquid compositions of Examples 1 to 8 were those in which the generation of nanoscratches was suppressed as compared with that of Comparative Example 1, and Comparative Example 2 or Compared with those of No. 3, it was found that the polishing rate was excellent and the generation of nano scratches was suppressed.
Moreover, all the substrates obtained in Examples 1 to 8 had extremely small surface roughness.

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

Claims (4)

A polishing composition for a magnetic disk substrate , which contains colloidal silica having an average primary particle diameter of 1 to 50 nm and water and having a pH of 0.1 to 4 that satisfies the following conditions:
(1) The colloidal silica of 0.56 μm or more and less than 1 μm is 100,000 or less per 1 cm ^{3 of the} polishing composition, and (2) the colloidal silica of 1 μm or more is 0.2% relative to the total colloidal silica in the polishing composition. 001% by weight or less. Furthermore, the polishing liquid composition of Claim 1 which satisfy | fills the following conditions:
(3) The colloidal silica of 3 μm or more is 0.0008% by weight or less based on the total colloidal silica in the polishing composition.   The polishing composition according to claim 1 or 2, wherein the content of colloidal silica in the polishing composition is 0.5 to 20% by weight. A method for manufacturing a substrate, comprising a step of polishing a magnetic disk substrate using the polishing composition according to any one of claims 1 to 3 .