GB2535070A

GB2535070A - Method for producing polishing liquid composition

Info

Publication number: GB2535070A
Application number: GB1607387.6A
Authority: GB
Inventors: Sato Kanji
Original assignee: Kao Corp
Current assignee: Kao Corp
Priority date: 2013-10-24
Filing date: 2014-10-23
Publication date: 2016-08-10
Also published as: MY181224A; JP6425965B2; JP2015108135A; GB201607387D0; TWI639690B; TW201522597A; WO2015060410A1

Abstract

This method for producing a polishing liquid composition comprises a step for filtering a silica dispersion liquid to be processed, which contains colloidal silica, with use of a filter containing a filtration assistant. The colloidal silica has an average particle diameter of primary particles of from 1 nm to 50 nm (inclusive) as determined by a titration method, and the filtration assistant has a hydroxyl group density of 0.40 × 10-5 mol/m2 or more. It is preferable that the ratio of the average particle diameter of primary particles of the colloidal silica as determined by a titration method to the average particle diameter of the filtration assistant as determined by a laser particle size distribution measuring instrument is from 1.20 × 10-3 to 4.20 × 10-3 (inclusive).

Description

DESCRIPTION

METHOD FOR PRODUCING POLISHING LIQUID CO1VIPOSMON

Thchnical Field

[0001] The present disclosure relates to a method for producing a polishing composition, a polishing composition, and a method for producing a magnetic disk substrate.

Background Art

[0002] In recent years, there is a demand for high capacity and reduction in a diameter in memory hard disk drives, and in order to increase recording density, there is a request that a unit recording area be reduced by decreasing a floating amount of a magnetic head. Along with this, requirement for surface quality after polishing is becoming strict year after year also in the step of producing a magnetic disk substrate. That is, it is necessary to reduce surface roughness, micro waviness, roll-off, and protrusions in accordance with reduction in a flying height of a head, and the allowable number of scratches per substrate surface and the size and depth thereof are decreasing along with the reduction in a unit recording area.

[0003] Further, integration and speed are increasing also in a semiconductor field, and particularly in high integration, there is a demand that wiring be finer. Consequently, in a method for producing a semiconductor substrate, depth of focus becomes small at a time of exposing a photoresist to light, and hence, further surface smoothness is desired.

[0004] In order to reduce flaws (scratches) on a surface of an object to be polished for the purpose of improving surface smoothness in response to the above-described request, there has been proposed a polishing composition where the number of coarse particles is reduced by centrifugation and multistage filtration, and a method for producing the polishing composition (Patent Documents 1 and 2, for example).

Further, there has been proposed a method for producing a polishing silica sol including a step of passing a silica sol through a diatomite filter (Patent Documents 3 and 4 for example).

Prior Art Documents Patent Documents

[0005] Patent Document 1: JP 2006-075975 A Patent Document 2: JP 2006-136996 A Patent Document 3: JP 2012-086357 A Patent Document 4: JP 2007-099586 A

Disclosure of Invention

Problem to be Solved by the Invention [0006] 'Ib cope with the demand for high density such as high capacity and high integration, it is necessary to further reduce the number of scratches on a substrate surface. Such scratches are partly due to coarse particles and gelled substances contained in colloidal silica. General colloidal silica on the market contains coarse particles and gelled substances. Conventional methods for removing the coarse particles and gelled substances require centrifugation or multistage filtration of raw materials of an abradant dispersion. As a result, the production time becomes long, and the production cost is increased.

[0007] In one aspect, the present invention relates to a method for producing a polishing composition that can efficiently remove coarse particles and gelled substances in a raw silica dispersion containing colloidal silica through high-precision filtration, thereby reducing the number of scratches on a substrate surface after polishing.

Means for Solving Problem [0008] The present invention relates to a method for producing a polishing composition, including a step of filtering a raw silica dispersion containing colloidal silica with a filter containing a filter aid (hereinafter, also referred to as "production method of the polishing composition of the present disclosure". In the production method of the polishing composition of the present disclosure, the average primary particle diameter of the colloidal silica as determined by titration is 1 nm to 50 nm.

Further, the filter aid has a hydroxyl group density of 0.40 x 10-5 mol/m2 or more.

[0009] In another aspect, the present invention relates to a polishing composition that is produced or can be produced by the production method of the polishing composition of the present disclosure.

[0010] In another aspect, the present invention relates to a method for producing a magnetic disk substrate, including a step of polishing a surface to be polished of a substrate to be polished by supplying the polishing composition obtained by the production method of the polishing composition of the present disclosure onto the surface to be polished.

[0011] In another aspect, the present invention relates to a filter aid used in the production method of the polishing composition of the present disclosure, wherein the filter aid has a hydroxyl group density of 0.40 x 10-5 mal/m2 or more.

[0012] In another aspect, the present invention relates to a method for producing the filter aid used in the production method of the polishing composition of the present disclosure, including a step of mixing diatomite having a hydroxyl group density of less than 040 x 10-5 mollm2 with an aqueous solution of acid, and thereafter subjecting the diatomite to a deoxidation treatment.

Effects of the Invention [0013] The present disclosure can provide an effect that coarse particles and gelled substances in the raw silica dispersion containing colloidal silica can be removed effectively through high-precision filtration, and thus it is possible to produce a polishing composition that can reduce the number of scratches on a substrate surface after polishing.

Description of the Invention

[0014] In the present invention, a filter aid used in a filter containing a filter aid (hereinafter, also referred to as "filter-aid containing filter'') is controlled to have a hydroxyl group density of not less than a predetermined value. Hence, when the average primary particle diameter of colloidal silica is 1 nm to 50 nm, the filteraid containing filter exhibits high filtration precision against coarse particles and gelled substances. Therefore, the polishing composition that is produced by the production method of the polishing composition of the prevent invention can reduce scratches on a substrate surface after polishing.

[0015] The term "coarse particle" in the present disclosure refers to a coarse colloidal silica particle having a particle diameter of 0.5 pm or more. Further, the term "gelled substance" in the present disclosure refers to a silica aggregate of 0.05 to 0.5 pm. The amount of the coarse particles and gelled substances in the polishing composition can be evaluated by "0.45 pm filter liquid passing quantity" described below.

[0016] The term "scratch" in the present disclosure refers to a physical property to take into account for achieving high density or high integration in a memory hard disk substrate or semiconductor element substrate, the scratch being a minute flaw on a substrate surface having a depth of 1 nm or more and less than 100 rim, a width of 5 nm or more and less than 500 nm, and a length of 100 pm or more. The scratch can be detected with an optical surface analyzer (OSA6100, produced by KLA-'lbncor Corporation) and an atomic force microscope (AFM) described in the below-mentioned examples.

[0017] The term "filtration precision" in the present disclosure refers to a degree to which coarse particles and gelled substances are filtered by the filter-aid containing filter. High "filtration precision" means that the filter-aid containing filter has a high capturing rate of coarse particles and gelled substances. The "filtration precision" can be evaluated by a liquid passing quantity (g) until a predetermined filter-aid containing filter is clogged, which is measured by passing the polishing composition or silica dispersion through the filter-aid containing filter under a constant pressure. The liquid passing quantity can be expressed as a microfiltration value (MF value). A larger liquid passing quantity (i.e., larger MF value) indicates less inclusion of coarse particles and gelled substances in the polishing composition or silica dispersion, and high filtration precision. Hence, there is a correlation between the MF value and the number of scratches that the number of scratches decreases with a larger MF value. It can be said that the silica dispersion with a large MF value can reduce the number of scratches. It also can be said that the polishing composition prepared using the silica dispersion with a large MF value can reduce the number of scratches.

[0018] The mechanism of reducing the number of scratches in the present invention is assumed as follows. When a filter-aid containing filter is used to remove coarse particles and gelled substances of colloidal silica from a raw silica dispersion containing colloidal silica, the coarse particles and gelled substances are captured by submicronic pores originally present in a filter aid of the filter-aid containing filter, or gaps between particles in a filter aid layer (cake layer) created by the filter aid if the filter-aid containing filter includes a filter aid layer. The present invention adopts a filter aid whose surface hydroxyl group density is higher than that of conventional filter aids, specifically, the present invention adopts a filter aid having a hydroxyl group density of 0.40 x 103 mol/m2 or more. Thus, the filter aid of the present invention increases the frequency of hydrogen bonding formed by mutual interactions between hydroxyl groups of the filter aid and hydroxyl groups of the coarse particles and gelled substances, as compared with the case of using conventional filter aids. Therefore, in the present invention, the mutual interactions promote the capturing of the coarse particles and gelled substances by physical barriers such as the submicronic pores and the gaps between particles, thereby capturing them more effectively. As a result, the polishing composition and silica dispersion can be filtered highly precisely, and the number of scratches is reduced. Note here that the present invention is not limited to these mechanisms.

[0019] [Filter aid] In one or more embodiments, examples of the filter aid used in the production method of the polishing composition of the present disclosure include insoluble mineral materials such as diatomite, silica, kaolin, acid white clay, pearlite, bentonite, and talc. Among these, silicon dioxide, diatomite and pearlite are preferred, diatomite and pearlite are more preferred, and diatomite is further preferred, from the viewpoint of reducing coarse particles and gelled substances and reducing scratches on a substrate surface after polishing.

[0020] The filter aid (preferably diatomite) has a hydroxyl group density of 0.40 x 103 mol/m2 or more, preferably 0.41 x 10-5 mol/m2 or more, and more preferably 0.43 x 10-5 mol/m2 or more from the view of enhancing filtration precision, and preferably 2.0 x 10-5 mol/m2 or less, and more preferably 1.5 x 10-5 mol/m2 or less from the viewpoint of enhancing productivity. The hydroxyl group density of the filter aid can be determined by a method described in the examples. The hydroxyl group density of the filter aid can be controlled as below.

[0021] In the case of increasing the hydroxyl group density of diatomite, for example, commercially available diatomite and an aqueous solution of acid are mixed sufficiently, and the mixture is left to stand for a predetermined time and thereafter subjected to a deoxidation treatment. By this method, hydroxyl groups can be introduced into diatomite without changing the properties of the filter aid (e.g., the average pore diameter, pore volume, and CV value), which is preferable. Accordingly, the polishing composition that is produced by the production method of the polishing composition of the present invention can perform polishing at a speed equivalent to that in the case of using polishing compositions produced using conventional filter aids whose hydroxyl group density is not controlled at 0.40 x 10-5 mol/m2 or more, while reducing scratches.

[0022] In the deoxidation treatment, diatomite is washed with ion exchange water or ultrapure water, and the washing is repeated until the ion exchange water or ultrapure water used for washing substantially neutralizes. Specifically, a supernatant is removed from the mixture containing diatomite and an aqueous solution of acid after standing, and ion exchange water or ulterpure water is added to a residue (diatomite) of the mixture from which the supernatant is removed, followed by sufficient stirring and mixing. Next, the mixture is left to stand for a predetermined time, and a supernatant is removed from the mixture after standing. This operation is repeated until a supernatant neutralizes (pH = 5 to 8). After this washing of diatomite with ion exchange water or ultrapure water, diatomite is filtered on filter paper and dried by, e.g., natural drying. Thus, diatomite having a higher hydroxyl group density than diatomite without acid treatment can be obtained. The amount of hydroxyl groups to be introduced into diatomite can be controlled by the concentration of acid in the aqueous solution of acid, the soaking time of diatomite in the aqueous solution of acid, or the like. The mechanism of the increase of the hydroxyl group density is uncertain, but the following two mechanisms are presumed. [0023] The treatment with add in the aqueous solution causes metal oxides such as A1203, Fe02 and MgO present in the surface of diatomite to be eluted, and a new diatomite surface appears, resulting in an increase of the hydroxyl group density.

[0024] Further, in the aqueous solution, bonding that forms the skeleton of diatomite and that is created between oxygen atoms and metal species such as Al, Fe, and Mg that are bonded to the oxygen atoms cuts off, and hydrogen ions in the aqueous solution are bonded to the oxygen atoms, resulting in an increase of the hydroxyl group density.

[0025] Examples of the acid used for adjusting the aqueous solution of acid include inorganic acids and organic acids. The inorganic adds are preferably mineral adds.

The organic adds can be various kinds of organic adds; however, it is found that the increase of the hydroxyl group density of diatomite is strongly correlated with an add dissociation constant (pKa). That is, from the viewpoint of increasing the hydroxyl group density of diatomite, the organic adds preferably have a pKa of less than 5, and more preferably less than that. The lower limit of the pica of the organic adds is not limited particularly, but is preferably 1 or more from the practical viewpoint.

[0026] In one or more embodiments, from the above-described viewpoint, the specific add used for adjusting the aqueous solution of add is preferably at least one kind selected from the group consisting of hydrochloric acid, nitric acid, phosphoric add, phosphonic acid such as 1-hydroxyethylidene-1,1-diphosphonic acid, phosphinic add, and organic acid having a pica of less than 4, more preferably at least one kind selected from the group consisting of hydrochloric add, nitric acid, phosphoric add, phosphonic add, phosphinic add, and organic add having a pKa of less than 3.5, further preferably at least one kind selected from the group consisting of nitric add, phosphoric acid, phosphonic add, phosphinic add, and organic add having a pKa of 3.1 or less, and still further preferably at least one kind selected from the group consisting of phosphonic add and phosphinic add, from the viewpoint of enhancing filtration precision and reducing the number of scratches.

[0027] The concentration of the add in the aqueous solution of add is preferably 0.05 mol/L or more, more preferably 0.1 mol/L or more, and further preferably 0.15 mol/L or more, from the viewpoint of obtaining a sufficient elution amount of metal species and increasing the hydroxyl group density. The concentration thereof is preferably 2.0 mol/L or less, and more preferably LO mol/L or less, from the viewpoint of preventing excessive elution of metal species.

[0028] In the case of using 3.5 mass% of the aqueous solution of add, the content of the acid in the aqueous solution of add with respect to 100 parts by mass of diatomite to be mixed therewith is preferably 200 parts by mass or more, more preferably 500 parts by mass or more, and further preferably 10000 parts by mass or more, from the viewpoint of obtaining a sufficient elution amount of metal species and increasing the hydroxyl group density [0029] In the treatment with acid, the standing time of the mixture containing diatomite and an aqueous solution of acid is preferably 5 minutes or more, more preferably 30 minutes or more, and further preferably 1 hour or more from the viewpoint of obtaining a sufficient elution amount of metal species and increasing the hydroxyl group density, and preferably 72 hours or less from the viewpoint of productivity [0030] The above explains the treatment with acid as an exemplary method for introducing hydroxyl groups into diatomite. However, hydroxyl groups can be introduced into diatomite by a method (treatment with alkali), including: mixing commercially available diatomite and an alkali aqueous solution (e.g., an aqueous solution of sodium hydroxide); leaving the mixture to stand for a predetermined time; and thereafter subjecting the mixture to a dealkalization treatment.

[0031] In the case of decreasing the hydroxyl group density of diatomite, for example, diatomite (an exemplary filter aid) is baked in a baking furnace. The diatomite is baked by raising the temperature inside the baking furnace from the room temperature up to preferably 700°C, more preferably 750°C, and further preferably 800°C in a state where the diatomite is placed in the baking furnace, and keeping the temperature for preferably 3 hours or more, more preferably 5 hours or more, and further preferably 10 hours or more, from the viewpoint of baking the entire system more reliably. The atmosphere temperature inside the baking furnace is preferably raised by airflow, and the flow speed is preferably 0.5 to 5 Llmin, and more preferably 2 to 3 L/min, from the viewpoint of uniformizing-the temperature inside the baking furnace.

[0032] [CV value of particle size distribution of filter aid] The term "CV value of particle size distribution of filter aid" in the present disclosure refers to an index expressing the spread of the particle size distribution, and is obtained by the following formula: CV value (%) = standard deviation / average particle diameter. In one or more embodiments, the CV value is obtained as a percentage (%) of value obtained by dividing an arithmetic standard deviation obtained by measuring the filter aid with a laser diffraction-scattering type particle size distribution analyzer, by a value obtained as a volume-based median diameter. In the present disclosure, the CV value is a value calculated by measurement of a scattering intensity distribution at a detection angle of 90° by the Marquardt method.

The CV value can be specifically obtained by a method described in the examples.

[0033] The CV value of the particle size distribution of the filter aid is preferably 70% or more, more preferably 75% or more, further preferably 80% or more, and still further preferably 85% or more from the viewpoint of reducing coarse particles and gelled substances and reducing scratches on a substrate surface after polishing, and 10 preferably 100% or less, and more preferably 99% or less from the viewpoint of [0034] [Laser average particle diameter of filter aid] The term laser average particle diametef' of the filter aid in the present disclosure refers to an average particle diameter of the filter aid as measured by a laser particle size distribution measuring device, and is a value calculated by measurement of a scattering intensity distribution at a detection angle of 90° by the Marquardt method in the present disclosure. The laser average particle diameter of the filter aid can be measured by a method described in the examples.

[0035] The laser average particle diameter of the filter aid is preferably 0.5 pm or more, more preferably 1 pm or more, further preferably 4.5 pm or more, still further preferably 8 pm or more, and still further preferably 10 pm or more from the viewpoint of reducing coarse particles and gelled substances and reducing scratches on a substrate surface after polishing, and preferably 100 pm or less, more preferably 60 pm or less, further preferably 50 pm or less, still further preferably 40 pm or less, still further preferably 20 pm or less, and still further preferably 13 pm or less from the same viewpoint.

[0036] [Average pore diameter of filter aid] The average pore diameter of the filter aid as measured by a mercury intrusion method is preferably 0.1 to 3.5 pm, more preferably 0.1 to 3.0 pm, further preferably 0.1 to 2.7 pm, and still further preferably 0.1 to 2.6 pm, from the viewpoint of reducing scratches and particles and enhancing productivity of the polishing composition. The term "average pore diameter as measured by a mercury intrusion method" in the present invention refers to an average value of a pore diameter based on a volume of filter aid particles.

[0037] [Ratio of average primary particle diameter of colloidal silica to laser average particle diameter of filter aid] The ratio of the average primary particle diameter of the colloidal silica of the raw silica dispersion as determined by titration to the laser average particle diameter of the filter aid (average primary particle diameter of the colloidal silica / laser average particle diameter of the filter aid) (hereinafter, also referred to as "average particle diameter ratio of silica to filter aid") is preferably 1.20 x 10-3 or more, more preferably 1.35 x 10-3 or more, further preferably 1.40 x 10-3 or more, and still further preferably 1.42 x 10-3 or more, from the viewpoint of reducing coarse particles and gelled substances and reducing scratches on a substrate surface after polishing. The average particle diameter ratio of silica to filter aid is preferably 4.20 x 10-3 or less, more preferably 3.80 x 10-3 or less, further preferably 3.00 x 10-3 or less, still further preferably 2.50 x 10-3 or less, still further preferably 2.00 x 10-3 or less, and still further preferably 1.50 x 10-3 or less from the same viewpoint.

[0038] [Integrated pore volume of 0.15 pm or less of filter aid as measured by nitrogen adsorption method] The integrated pore volume of pores having a diameter of 0.15 pm or less of the filter aid as measured by a nitrogen adsorption method is preferably 0 3 mL/g or more, more preferably 0.4 mUg or more, and further preferably 0.6 mUg or more, from the viewpoint of reducing scratches and particles. The integrated pore volume is preferably 100.0 mIJg or less, more preferably 50 0 mL/g or less, and further preferably 10 0 mUg or less, from the viewpoint of enhancing productivity of the polishing composition. The integrated pore volume of 0.15 pm or less of the filter aid can be measured by a method described in the examples.

[0039] [Integrated pore volume of 0 5 pm or less of filter aid as measured by mercury intrusion method] The integrated pore volume of pores having a diameter of 0.5 pm or less of the filter aid as measured by a mercury intrusion method is preferably 2.5 mUg or more, more preferably 2.7 mUg or more, further preferably 3 0 mL/g or more, still further preferably 4.0 mUg or more, and still further preferably 4.5 mUg or more, from the viewpoint of reducing scratches and particles. The integrated pore volume of pores having a diameter of 0.5 pm or less of the filter aid as measured by a mercury intrusion method is preferably 1000 mkt or less, more preferably 100 mUg or less, further preferably 50 mUg or less, still further preferably 20 mUg or less, and still further preferably 10 mUg or less, from the viewpoint of enhancing productivity of the polishing composition. Herein, the "integrated pore volume of 0.5 pm or less as measured by a mercury intrusion method" of the filter aid refers to a total of pore volumes of 0 5 pm or less in a pore distribution of a volume standard of filter aid particles as measured by a mercury intrusion method, and can be measured by a method described in the examples.

[0040] [Raw silica dispersion] The term "raw silica dispersion" in the present disclosure refers to silica slurry (silica dispersion) before being subjected to filtration through use of a filter aid containing filter. In one or more embodiments, examples of the raw silica dispersion include a dispersion containing colloidal silica and water, a dispersion further containing other components in addition to colloidal silica and water, and a slurry of general-purpose colloidal silica. In another embodiment, examples of the raw silica dispersion include those which are produced by mixing other components to be blended in a polishing composition described later. The raw silica dispersion is preferably in a state in which colloidal silica is dispersed.

[0041] In the production method of the polishing composition of the present disclosure, a polishing composition can be produced by subjecting a raw silica dispersion to filtration through use of a filter containing the filter aid (also referred to as "filter-aid containing filter" in the present disclosure). Specifically, a polishing composition can be produced by subjecting the raw silica dispersion produced by mixing colloidal silica, water, an add, and other components such as an oxidiser to the above-described filtration or subjecting a raw silica dispersion containing colloidal silica and water to the above-described filtration, and thereafter mixing other components with the obtained filtrate (silica dispersion). A polishing composition is preferably produced by the method of subjecting a raw silica dispersion containing colloidal silica and water to the above-described filtration, and thereafter mixing other components with the obtained filtrate (silica dispersion), from the viewpoint of easy processing in the production of the polishing composition.

[0042] [Average primary particle diameter of colloidal silica] The average primary particle diameter of the colloidal silica of the raw silica dispersion refers to an average primary particle diameter thereof as determined by titration unless otherwise specified. The average primary particle diameter by titration is specifically measured as follows. First, a mixture is obtained by adding water to colloidal silica slurry. Next, the pH of the mixture is adjusted (e.g., 3.0) with a hydrochloric acid standard solution or the like using a potentiometric titrator. Next, sodium chloride and water are added to the pH-adjusted mixture and sodium chloride is dissolved therein. The obtained sample solution is thoroughly soaked in a constant temperature water tank. Next, the sample solution is titrated with a standard solution (sodium hydroxide solution, etc.) using the potentiometric titrator. An amount (g) (A) of the solute of the standard solution used to change the pH of the sample solution from 4.0 to 9.0 is read, and an amount (g) (B) of the solute of the standard solution required for titration in which colloidal silica slurry is not added to the sample solution is read. Then, an average particle diameter (nm) is calculated by the following formula.

Average particle diameter (nm) = 3100 ÷ 26.5 x (A-B) ÷ collected amount of sample (colloidal silica (solid content)) (g) [0043] The average primary particle diameter of the colloidal silica of the raw silica dispersion is 1.0 to 50 nm from the viewpoint of reducing coarse particles and gelled substances and reducing scratches on a substrate surface after polishing, and it is more preferably 5.0 nm or more, further preferably 10.0 nm or more, still further preferably 12.0 nm or more, and preferably 45 nm or less, more preferably 42 or less, and further preferably 40 nm or less from the same viewpoint. In one or more embodiments, the raw silica dispersion and the polishing composition in the present disclosure contain colloidal silica having an average primary particle diameter within the above-described range.

[0044] The colloidal silica used in the present disclosure can be obtained by, for example, a production method of generating colloidal silica from silicic acid aqueous solution. Further these polishing particles whose surface is modified or reformed with a functional group, the polishing particles formed into composite particles with a surfactant or another abradant, and the like can be used.

[0045] The content of the colloidal silica in the raw silica dispersion is preferably 1 mass% or more, more preferably 10 mass% or more, further preferably 20 mass% or more, still further preferably 30 mass% or more, and preferably 50 mass% or less, more preferably 45 mass% or less, further preferably 43 mass% or less, and still further preferably 40 mass% or less, from the viewpoint of reducing scratches and enhancing productivity [0046] In one or more embodiments, the pH of the raw silica dispersion at 25°C is preferably 8.5 or more, more preferably 8.8 or more, further preferably 9.0 or more, and preferably 11 or less, more preferably 10.8 or less, and further preferably 10.5 or less, from the viewpoint of preventing formation of coarse particles and enhancing stability of colloidal silica. The pH of the raw silica dispersion can be adjusted with a known pH adjuster. Examples of preferred pH adjuster include sodium hydroxide, potassium hydroxide, ammonia, and tetramethyl ammonium hydroxide.

[0047] [Filter-aid containing filter] The filter-aid containing filter used in the production method of the polishing composition of the present disclosure is not particularly limited as long as it contains the filter aid on the surface of a filter and/or in the filter. In the production method of the polishing composition of the present disclosure, for example, body feeding further may be combined with precoating. The filter opening of the filter-aid containing filter as measured by a method specified by JIS 3801 is preferably 15 pm or less, more preferably 12 pm or less, further preferably 10 pm or less, and still further preferably 8 pm or less, from the viewpoint of preventing leakage of the filter aid. Further, the filter opening of the filter-aid containing filter is preferably 0 5 pm or more, further preferably 10 pm or more, still further preferably 3 0 pm or more, and still further preferably 5 0 pm or more, from the viewpoint of enhancing a filter liquid passing speed. Herein, the precoating refers to a method for forming a cake filtration filter, that is, forming a filter aid thin layer having a thickness of about several millimeters on a filter material (base material such as filter paper) described later. For example, there is a method for forming a filter aid layer by dispersing filter aid particles in water and filtering out a filter aid with a filter material. Further, the body feeding refers to a method for filtering an unfiltered solution to be subjected to cake filtration while pouring a predetermined amount of a filter aid to the unfiltered solution at a time of filtration, and a purpose of adding the filter aid is to improve filterability of the unfiltered solution. The body feeding is effective for an unfiltered solution whose cake resistance is immediately maximized (which becomes unable to be filtered) due to a minute particle diameter.

[0048] The content (g/cm2) of the filter aid in the filter aid containing filter is preferably 0.001 g/cm2 or more, more preferably 0.005 g/cm2 or more, further preferably 0.01 g/cm2 or more, still further preferably 0.02 g/cm2 or more, still further preferably 0.04 g/cm2 or more, and still further preferably 0.1 g/cm2 or more, from the viewpoint of reducing scratches Further, the content thereof is preferably 1 g/cm2 or less, more preferably 0.8 g/cm2 or less, further preferably 0.6 g/cm2 or less, still further preferably 0.4 g/cm2 or less, still further preferably 0.3 g/cm2 or less, and still further preferably 0.2 g/cm2 or less, from the viewpoint of enhancing a filtration speed. [0049] Examples of the filter material for the filter-aid containing filter include: filter paper; plastics such as polyethylene, polypropylene, polyether sulphone, cellulose acetate, nylon, polycarbonate, and 'Mon (registered trademark); ceramics; and metal mesh. From the viewpoint of reducing scratches, a plastic mesh made of filter paper, polyethylene, polypropylene, polyether sulphone, cellulose acetate, nylon, polycarbonate or Wort (registered trademark) is preferred, a plastic mesh made of filter paper, polyethylene, polypropylene, polyether sulphone, cellulose acetate or nylon is more preferred, and a plastic mesh made of filter paper, polyethylene or polypropylene is further preferred.

[0050] The filter opening of the filter material (base material) is preferably 15 pm or less, more preferably 12 pm or less, further preferably 10 pm or less, and still further preferably 8 pm or less, from the viewpoint of preventing leakage of the filter aid. Further, the filter opening of the filter material (base material) is preferably 0.5 pm or more, further preferably 10 pm or more, still further preferably 3.0 pm or more, and still further preferably 5 0 pm or more, from the viewpoint of enhancing a filter liquid passing speed.

[0051] Although the shape of the filter-aid containing filter is not particularly limited, a sheet type, a cylinder type, a disc type, and a folded type are preferred; a sheet type, a disc type, and a folded type are more preferred; and a disc type and a folded type are further preferred, from the viewpoint of ease of handling and reducing scratches. [0052] [Filtration step] In the production method of the polishing composition or silica dispersion of the present disclosure, a filtration pressure among the conditions in the filtration step using the filteraid containing filter is preferably 0.16 MPa or more, more preferably 0.18 MPa or more, and further preferably 0.20 MPa or more, from the viewpoint of reducing coarse particles and gelled substances and reducing scratches on a substrate surface after polishing. The filtration pressure in the filtration step is preferably 0.49 MPa or less, more preferably 0.45 MPa or less, further preferably 0.40 MPa or less, still further preferably 0.30 MPa or less from the same viewpoint. The term "filtration pressure" in the present disclosure refers to a pressure per unit area to be applied to the filter aid. In one or more embodiments, the filtration pressure can be adjusted by regulating the output pressure with a regulator.

[0053] In the production method of the polishing composition or silica dispersion of the present disclosure, a filtration flow rate among the conditions in the filtration step using the filteraid containing filter is preferably 10.0 g/(min * m2) or more, more preferably 12.0 g/(min * m2) or more, and further preferably 14.0 g/(min * m2) or more, from the viewpoint of reducing coarse particles and gelled substances and reducing scratches on a substrate surface after polishing. The filtration flow rate in the filtration step is preferably 40.0 g/(min * m2) or less, more preferably 38.0 g/(min * m2) or less, and further preferably 36.0 g/(min * m2) or less from the same viewpoint. The term "filtration flow rate" in the present disclosure refers to a weight per unit time to be filtered per unit area. In one or more embodiments, the filtration flow rate can be adjusted by regulating a valve on the secondary side (filter exit).

[0054] The number of stages of the filteraid containing filter is preferably 1 to 5, more preferably 1 to 3, and further preferably 1 to 2, from the viewpoint of improving both filtration precision and productivity.

[0055] In the production method of the polishing composition or silica dispersion of the present disclosure, it is preferable to use a depth filter and a pleats filter by further combining them, which have been conventionally used for producing a polishing composition, from the viewpoint of reducing coarse particles and gelled substances and reducing scratches on a substrate surface after polishing.

[0056] In one or more embodiments, in the production method of the polishing composition of the present disclosure, it is preferred that a raw silica dispersion be filtered with a depth filter and then with a filter-aid containing filter, and it is more preferred that a raw silica dispersion be filtered with a filter-aid containing filter and further with a pleats filter, from the viewpoint of reducing coarse particles and gelled substances and reducing scratches on a substrate surface after polishing. It is presumed that, by removing particularly large coarse particles with a depth filter, excellent performance of the filter* aid containing filter is exhibited remarkably, which enables efficient removal of coarse particles and sediment.

[0057] Specific examples of the depth filter used in the production method of the polishing composition or silica dispersion of the present disclosure include not only bag type filters (Sumitomo 3M T imited (currently 3M Japan Limited), etc.) but also cartridge type filters (Advantec Thyo Kaisha Ltd., Pall Corporation (Japan), Cuno Inc. (currently 3M Japan Products Limited), Daiwabo Co. Ltd., etc.).

[0058] The depth filter has a feature in that a porous structure of a filter material is coarse on an inlet side and fine on an outlet side, and becomes finer continuously or gradually from the inlet side to the outlet side. That is, the depth filter collects large particles of coarse particles in the vicinity of the inlet side and collect small particles in the vicinity of the outlet side, and hence, is capable of performing effective filtration.

The shape of the depth filter may be a bag type in a bag shape or a cartridge type in a hollow cylindrical shape. Further, a filter material having the above-described feature simply molded in a folded shape is classified into the depth filter, because such a filter material has a function of the depth filter. The depth filter may have one stage or multiple stages (for example, in series arrangement). It is preferred that filters having different opening diameters be formed in multiple stages in decreasing order of diameter, from the viewpoint of enhancing productivity. A combination of a bag type and a cartridge type may be used.

[0059] As the pleats filter used in the production method of the polishing composition or silica dispersion of the present disclosure, a cartridge type in a hollow cylindrical shape obtained by molding a filter material in a folded shape (pleats shape) (Advantec lbyo Kaisha Ltd., Pall Corporation (Japan), Cuno Inc. (currently 3M Japan Products Limited), Daiwabo Co. Ltd., etc.) generally can be used. Unlike the depth filter that collects particles in each portion in a thickness direction, the pleats filter includes a filter material having a small thickness, and is considered to collect particles mainly on a surface of the filter. In general, the pleats filter has high filtration precision. The pleats filter may have one stage or multiple stages (for example, in series arrangement).

[0060] In an entire filtration step, it is preferred to perform filtration using a depth filter, filtration using a filter-aid containing filter, and filtration using a pleats filter in this order, because the entire lives of the filters can be extended, and the polishing composition or silica dispersion of the present disclosure can be produced economically.

[0061] As a method of the filtration, a circulating system in which filtration is performed repeatedly or a one pass system may be used. Alternatively, a batch system in which the one pass system is repeated may be used. As a liquid passing method, for applying pressure, a pump is preferably used in the circulating system, and in the one pass system, a pressure filtration method in which a variation width of a filter inlet pressure is reduced by introducing an air pressure or the like into a tank, as well as a pump, can be used.

[0062] In the production method of the polishing composition or silica dispersion of the present disclosure, in addition to the use of the depth filter and the pleats filter, a general particle dispersion step or particle removal step may be provided. For example, a dispersion step using a high-speed dispersion device or a high-pressure dispersion device such as a high-pressure homogenizer and a coarse particle precipitation step using a centrifugal device or the like also can be used. In the case of treating particles by use of these devices, each treatment may be performed alone or a combined treatment of two or more kinds may be performed. There is no particular limitation on the order of the combined treatment. Further, conditions of the treatment and the number of times of the treatment also can be selected appropriately.

[0063] [0.45 pm filter liquid passing quantity] The polishing composition or silica dispersion (filtered raw silica dispersion) including a large amount of coarse particles and gelled substances causes clogging of a filter after passing therethrough, and reduces a liquid passing quantity. The 0.45 pm filter liquid passing quantity of the polishing composition or silica dispersion (liquid passing quantity with respect to a filter having a pore diameter of 0.45 pm) can be a criterion to judge the amount of the coarse particles and gelled substances present in the polishing composition or silica dispersion. Silica particles having a large average primary particle diameter also are prone to dog a filter, and reduce the 0.45 pm filter liquid passing quantity. Therefore, the "0.45 pm filter liquid passing quantity" is a suitable parameter for comparing polishing compositions or silica dispersions including silica particles having similar average primary particle diameters. [0064] The 0.45 pm filter liquid passing quantity of the polishing composition or silica dispersion (filtered raw silica dispersion) of the present disclosure is preferably 100 mL or more, more preferably 120 mL or more, further preferably 140 mL or more, still further preferably 150 mL or more, and still further preferably 180 mL or more, from the viewpoint of reducing scratches. Here, the 0.45 pm filter liquid passing quantity of the polishing composition or silica dispersion can be measured by a method described in the examples.

[0065] [Production method of silica dispersion] By the above-described filtration method, it is possible to obtain a silica dispersion with less coarse particles and gelled substances. Therefore, in another aspect, the present disclosure relates to a method for producing a silica dispersion, including a step of filtering a raw silica dispersion containing colloidal silica with a filter containing a filter aid, wherein an average primary particle diameter of the colloidal silica as determined by titration is 1 nm to 50 nm, and the filter aid has a hydroxyl group density of 0.40 x 10--5 mol/m2 or more. In one or more embodiments, the silica dispersion obtained by this production method allows production of a highly precisely filtered polishing composition of the present disclosure described below as well as production of a substrate with less scratches on a substrate surface after polishing.

[0066] [Polishing composition] In another aspect, the present disclosure relates to a polishing composition that is produced or can be produced by the production method of the polishing composition (hereinafter it is also referred to as "polishing composition of the present disclosure"). In one or more embodiments, the polishing composition of the present disclosure may include a below-mentioned acid or a salt thereof or alkali and/or an oxidizer, in addition to colloidal silica and water. However, the polishing composition of the present disclosure is not limited to these compositions and may include other components. In one or more embodiments, the polishing composition of the present disclosure may be a polishing composition that is obtained by mixing the silica dispersion obtained by the production method of the silica dispersion of the present disclosure, with other components as needed.

[0067] [Content of colloidal silica] The content of colloidal silica in the polishing composition of the present disclosure at the time of polishing an object to be polished is preferably 0.5 mass% or more, more preferably 1 mass% or more, further preferably 2 mass% or more, and still further preferably 4 mass% or more from the viewpoint of enhancing a polishing speed, and preferably 20 mass% or less, more preferably 15 mass% or less, further preferably 13 mass% or less, still further preferably 10 mass% or less, and still further preferably 8 mass% or less from the viewpoint of enhancing surface quality economically.

[0068] [Water] Examples of water used in the polishing composition of the present disclosure include ion exchange water, distilled water, and ultrapure water. The content of the water in the polishing composition of the present disclosure corresponds to a remainder after subtracting an abradant and other components from 100 mass%, and it is preferably 60 to 99 mass%, and more preferably 80 to 97 mass%.

[0069] [pH] Although the pH of the polishing composition of the present disclosure at 25°C may be adjusted appropriately in accordance with the object to be polished, it is preferably 0.1 to 7.0. Scratches tend to occur in an alkaline state as compared with an acidic state. Although the occurrence mechanism thereof is not clear, it is presumed that, in an alkaline atmosphere in which polishing particles react strongly with each other due to surface charge, aggregates of polishing primary particles or coarse particles contained in the polishing composition prevent the polishing particles from densely filling a space between the object to be polished and the polishing pad, and hence a load cannot be applied to the entire polishing surface evenly. The pH is preferably determined depending upon the kind of an object to be polished and required characteristics. When the material for an object to be polished is a metal material, the pH of the polishing composition is more preferably 6.0 or less, further preferably 5.0 or less, still further preferably 4.0 or less, still further preferably 3.0 or less, and still further preferably 2.0 or less, from the viewpoint of enhancing a polishing speed. The pH is more preferably 0.5 or more, further preferably 0.7 or more, still further preferably 0.9 or more, still further preferably 1.0 or more, and still further preferably 1.2 or more, from the viewpoint of reducing influence on a human body and preventing corrosion of a polishing device In a substrate for a precision component in which a material for an object to be polished is a metal material, such as an aluminum alloy substrate plated with nickel-phosphorus (Ni-P), the pH is more preferably 0.5 to 6.0, further preferably 0.7 to 5.0, still further preferably 0.9 to 4.0, still further preferably 1.0 to 3.0, and still further preferably 1.0 to 2.0, from the viewpoint of enhancing a polishing speed, reducing influence on a human body, and preventing corrosion of a polishing device.

[0070] [Acid] The polishing composition of the present disclosure may include an acid or a salt thereof, from the viewpoint of enhancing a polishing speed. Specific examples of the acid and the salt thereof include: 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 and amidosulfonic acid, or salts thereof organic phosphonic acids such as 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, hydroxyphosphonoacetic acid (PHAA), aminotri(methylenephosphonic acid), ethylenediaminetetramethylenephosphonic 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, 2-phosphono-1,2,4-butanetricarboxylic acid (PBTC), 1-phosphonobutane-2,3,4-tricarboxylic acid and a-methylphosphonosuccinic acid, or salts thereof amino carboxylic adds such as glutamic acid, picolinic acid and aspartic acid, or salts thereof, and carboxylic acids such as oxalic acid, nitroacetic acid, maleic acid and oxaloacetic acid, or salts thereof These may be used alone or in combination of two or more kinds. Among these, the polishing composition of the present disclosure preferably contains inorganic acids or organic phosphonic acids and salts thereof, from the viewpoint of reducing scratches.

[0071] Among the above-described inorganic acids or salts thereof, nitric acid, sulfuric acid, hydrochloric acid, perchloric acid, or salts thereof are more preferred. Among the above-described organic phosphonic acids or salts thereof; 1-hydroxyethylidene-1,1-diphosphonic acid, hydroxyphosphonoacetic acid, aminotrAmethylenephosphonic acid), ethylenediaminetetra(methylenephosphonic acid), diethylenetriaminepenta(methylenephosphonic acid), 2-phosphono-1,2,4-butanetricarboxylic acid, or salts thereof are more preferred, and 1-hydrcowethylidene-1,1-diphosphonk acid is further preferred. These may be used alone or in combination of two or more kinds.

[0072] There is no particular limitation on the salts of the above-described acids, and specific examples thereof include salts of metal, ammonia, and alkylamine. Specific examples of the metal include those belonging to Group 1A, 1B, 2A, 2B, 3A, 3B, 4A, 6A, 7A, or 8 in the periodic table (long-period form). From the viewpoint of reducing scratches, ammonia or metals belonging to Group lA are preferred.

[0073] The contents of the acid and the salt thereof in the polishing composition of the present disclosure is preferably 0.001 to 5 mass%, more preferably 0.01 to 4 mass%, further preferably 0.05 to 3 mass%, still further preferably 0.1 to 2.0 mass%, and still further preferably 0.1 to 1.0 mass%, from the viewpoint of enhancing a polishing speed and reducing scratches on a substrate surface after polishing.

[0074] [Oxidizer] The polishing composition of the present disclosure preferably contains an oxidizer, from the viewpoint of enhancing a polishing speed. Examples of the oxidizer that can be used in the polishing composition of the present disclosure include a peroxide, permanganic acid or a salt thereof, chromic acid or a salt thereof; peroxoacid or a salt thereof, oxygen acid or a salt thereof, metal salts, nitric acids, and sulfuric acids, from the viewpoint of enhancing a polishing speed.

[0075] Examples of the peroxide include hydrogen peroxide, sodium peroxide, and barium peroxide. An example of permanganic acid or a salt thereof is potassium permanganate. Examples of chromic acid or a salt thereof include a chromic acid metal salt and a dichromic add metal salt. Examples of peroxoacid or a salt thereof include peroxodisulfuric acid, ammonium peroxodisulfate, a peroxodisulfuric acid metal salt, peroxophosphoric acid, peroxosulfuric acid, sodium pemicoborate, performic acid, peracetic acid, perbenzoic acid, and perphthalic acid. Examples of oxygen acid or a salt thereof include hypochlorous acid, hypobromous acid, hypoiodous acid, chloric acid, bromic acid, iodic acid, sodium hypochlorite, and calcium hypochlorite.

Examples of the metal salts include iron (III) chloride, iron (III) sulfate, iron (III) 10 nitrate, iron (III) citrate, and ammonium iron (I11) sulfate.

[0076] Examples of a preferred oxidizer include hydrogen peroxide, iron (III) nitrate, peracetic acid, ammonium peroxodisulfate, iron (HI) sulfate, and ammonium iron (III) sulfate. A more preferred oxidizer is hydrogen peroxide, from the viewpoint of being used for general purposes without metal ions adhering to a surface and being inexpensive. These oxidizers may be used alone or in combination of two or more kinds.

[0077] The content of the oxidizer in the polishing composition is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, and further preferably 0.1 mass% or more from the viewpoint of enhancing a polishing speed, and the content is preferably 4 mass% or less, more preferably 2 mass% or less, and further preferably 1 mass% or less from the viewpoint of reducing surface roughness of a substrate. [0078] [Other components] Further, the polishing composition can be blended with other components as needed. In one or more embodiments, examples of such other components include a heterocyclic aromatic compound, a water-soluble polymer having an anionic group (also referred to as "anionic water-soluble polymer"), an aliphatic amine compound, and an alicyclic amine compound. In one or more embodiments, further examples of such other components include a thickener, a dispersant, an anticorrosion agent, a basic substance, and a surfactant.

[0079] [Heterocyclic aromatic compound] The polishing composition at the time of polishing an object to be polished preferably contains a heterocyclic aromatic compound (including salts thereof). The heterocyclic aromatic compound to be contained in the polishing composition of the present disclosure is preferably a heterocyclic aromatic compound containing 2 or more nitrogen atoms in its heterocycle, more preferably 3 or more nitrogen atoms, further preferably 3 to 9 nitrogen atoms, still further preferably 3 to 5 nitrogen atoms, and still further preferably 3 or 4 nitrogen atoms in its heterocycle, from the viewpoint of reducing scratches and particles on a substrate after polishing.

[0080] The heterocyclic aromatic compound is preferably pyrimidine, pyrazine, pyridazine, 1,2,3-triazine, 1,2,4-triazine, 1,2,5-triazine, 1,3,5-triazine, 1,2,4-oxadia7ole, 1,2,5-oxadiazole, 1,3,4-oxadiazole, 1,2,5-thiadiazole, 1,3,4-thiadiazole, 3-aminopyrazole, 4-aminopyravile, 3, 5-dimethylpyrazole, pyrazole, 2-aminoimidazole, 4-aminoimidazole, 5-aminoimidazole, 2-methylimidazole, 2-ethylimidazole, imidazole, benzimidazole, 1,2,3-triazole, 4-amino-1,2,3-triazole, 5-amino-1,2,3-triazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 5-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole, 1H-tetrazole, 5-aminotetrazole, 1H-benzotriazole, 1H-tolyltriazole, 2-aminobenzotriazole, 3-aminobenzotriazole, or an alkyl-substituted or an amine-substituted product thereof, more preferably 1H-benzotriazole or 1H-tolyltriazole, and further preferably 1H-benzotriazole, from the viewpoint of reducing scratches on a substrate after polishing. An exemplary alkyl group of the alkyl-substituted product includes a Ci-4 lower alkyl group, more specifically a methyl group or ethyl group. Further, examples of the amine-substituted product include 1-[N,N-bis(hydroxyethylene)aminomethyl]benzotriazole and 1-[N,N-bighydroxyethylene)aminomethylkolykriazole.

[0081] There is no particular limitation on the salts of the above-described heterocyclic aromatic compound, and specific examples thereof include metal salt, ammonium salt, and alkylamine salt. Specific examples of the metal include those belonging to Group 1A, 1B, 2A, 2B, 3A, 3B, 4A, 6A, 7A, or 8 in the periodic table (long-period form). Ammonia or metals belonging to Group lA are preferred, from the viewpoint of reducing scratches.

[0082] The content of the heterocyclic aromatic compound in the polishing composition is preferably 0.01 mass% or more, more preferably 0.02 mass% or more, further preferably 0.05 mass% or more, still further preferably 0.06 mass% or more, still further preferably 0.07 mass% or more, still further preferably 0.08 mass% or more with respect to the total mass of the polishing composition, and preferably 10 mass% or less, more preferably 5 mass% or less, further preferably 2 mass% or less, still further preferably 1 mass% or less, still further preferably 0.5 mass% or less, and still further preferably 0.3 mass% or less, from the viewpoint of reducing scratches and particles on a substrate after polishing. The polishing composition may contain one or two or more kinds of heterocyclic aromatic compounds.

[0083] [Anionic water-soluble polymer] The polishing composition at the time of polishing an object to be polished preferably contains an anionic water-soluble polymer, from the viewpoint of reducing scratches and particles on a substrate after polishing and reducing a maximum value of surface roughness (AFM-Rmax). It is presumed that the anionic water-soluble polymer prevents silica aggregates from coming out of the aperture of a polishing pad by reducing frictional vibration during polishing, and thus reduces scratches on a substrate after polishing and a maximum value of surface roughness (AFM-Rmax).

[0084] Examples of the anionic group of the anionic water-soluble polymer include a carboxylic acid group, a sulfonic acid group, a sulfate group, a phosphate group, and a phosphonic acid group. Among them, anionic water-soluble polymers having a carboxylic add group and/or a sulfonic acid group are more preferred, and anionic water-soluble polymers having a sulfonic acid group are further preferred, from the viewpoint of reducing scratches and particles and a maximum value of surface roughness (AFM-R.max). These anionic groups may take a form of neutralized salts. [0085] The water-soluble polymer having a carboxylic acid group and/or a sulfonic acid group may be a (co)polymer or its salt having at least one constitutional unit selected from the group consisting of a constitutional unit derived from a monomer having a carboxylic acid group and a constitutional unit derived from a monomer having a sulfonic add group. Examples of the monomer having a carboxylic add group include itaconic acid, (meth)acrylic acid, and maleic acid. Examples of the monomer having a sulfonic acid group include isoprenesulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, styrenesulfonic acid, methallylsulfonic acid, vinylsufonic acid, allylsulfonic acid, isoamylenesulfonic acid, and naphthalenesulfonic acid. The anionic water-soluble polymer may include two or more kinds of constitutional units derived from the monomer having a carboxylic acid group and two or more kinds of constitutional units derived from the monomer having a sulfonic add group.

[0086] Among these, in one or more embodiments, the anionic water-soluble polymer is preferably a copolymer including a constitutional unit derived from (meth)acrylic acid and a constitutional unit derived from a monomer containing a sulfonic acid group (hereinafter, also referred to as "(meth)acrylic acid/sulfonic acid copolymer". [0087] The (meth)acrylic acid/sulfonic acid copolymer may contain a constitutional unit derived from a monomer other than the monomer containing a sulfonic acid group and the (meth)acrylic add monomer, as long as the effect of the present invention is obtained.

[0088] The content of the constitutional unit derived from the monomer containing a sulfonic acid group with respect to all the constitutional units of the (meth)acrylic acid/sulfonic acid copolymer or its salt is preferably 3 mol% or more, more preferably 5 mol% or more, further preferably 8 mol% or more, and preferably 97 mol% or less, more preferably 50 mol% or less, and further preferably 30 mol% or less, from the viewpoint of reducing scratches. The (meth)acrylic acid monomer containing a sulfonic acid group is counted as the monomer containing a sulfonic acid group. [0089] When the (meth)acrylic acid/sulfonic add copolymer is a copolymer of (meth)acrylic acid and 2-(meth)acrylamide-2-methylpropane sulfonic acid, the molar ratio in polymerization between (meth)acrylic acid and 2-(meth)acrylamide-2-methylpropane sulfonic acid OmetWacrylic acid/2-(meth)acrylamide-2-methylpropane sulfonic acid) is preferably in a range from 95/5 to 40/60, more preferably 95/5 to 50/50, further preferably 95/5 to 60/40, still further preferably 95/5 to 70/30, still further preferably 95/5 to 75/25, still further preferably 95/5 to 80/20, and still further preferably 95/5 to 85/15, from the viewpoint of reducing scratches and particles on a substrate surface after polishing.

[0090] Preferred examples of the (meth)acrylic acid/sulfonic acid copolymer include a (meth)acrylic acid/isoprenesulfonic acid copolymer, a (meth)acrylic acid/2-(metWacrylamide-2-methylpropanesulfonic acid copolymer, and a (meth)acrylic acid/isoprenesulfonic acid/2-(metWacrylamide-2-methylpropenesulfonic acid copolymer, from the viewpoint of reducing scratches. Among these, a (meth)acrylic acid/2-(meth)acrylamide-2-methylpropanesulfonic acid copolymer is more preferred.

[0091] There is no particular limitation on the counter ions of the water-soluble polymer having an anionic group, and specific-examples thereof include ions of metal, ammonium, and alkylammonium. Specific examples of the metal include those belonging to Group Lk, 1B, 2A, 2B, 3A, 3B, 4A, 6A, 7A, or 8 in the periodic table (long-period form). Among these metals, the metals belonging to Group 1A, 3B, or 8 are preferred, and sodium and potassium belonging to Group lA are more preferred from the viewpoint of reducing surface roughness and scratches. Specific examples of the alkylammonium include tetramethylammonium, tetraethylammonium, and tetrabutylammonium. Among these salts, ammonium salt, sodium salt, and potassium salt are more preferred.

[0092] The weight average molecular weight of the anionic water-soluble polymer is preferably 500 to 100,000, more preferably 500 to 50,000, further preferably 500 to 20,000, still further preferably 1,000 to 10,000, still further preferably 1,000 to 8,000, still further preferably 1,000 to 5,000, still further preferably 1,000 to 4,000, and still further preferably 1,000 to 3,000, from the viewpoint of reducing scratches and particles and maintaining productivity. The weight average molecular weight is specifically measured by a measurement method described in the examples.

[0093] The content of the anionic water-soluble polymer in the polishing composition is preferably 0.001 to 1 mass%, more preferably 0.005 to 0.5 mass%, further preferably 0A)8 to 0.2 mass%, still further preferably 0.01 to 0.1 mass%, and still further preferably 0.01 to 0.075 mass%, from the viewpoint of satisfying both the reduction of scratches and particles and the enhancement of productivity [0094] [Aliphatic amine compound or alicyclic amine compound] The polishing composition at the time of polishing an object to be polished preferably contains an aliphatic amine compound or alicyclic amine compound, from the viewpoint of reducing scratches and particles on a substrate surface after polishing. The aliphatic amine compound or alicyclic amine compound preferably contains 2 or more nitrogen atoms in its molecule, from the viewpoint of reducing scratches and particles on a substrate surface after polishing. Further, the aliphatic amine compound or alicyclic amine compound preferably contains 4 or less nitrogen atoms in its molecule, more preferably 3 or less nitrogen atoms, and further preferably 2 or less nitrogen atoms, from the viewpoint of maintaining a polishing speed.

Therefore, the aliphatic amine compound or alicyclic amine compound preferably contains 2 to 4 nitrogen atoms in its molecule, more preferably 2 to 3 nitrogen atoms, and further preferably 2 nitrogen atoms, from the viewpoint of maintaining a polishing speed and reducing scratches and particles.

[0095] The aliphatic amine compound is preferably selected from the group consisting of ethylenediamine, N,N,N',N'-tetramethylethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, 3-(diethylamino)propylamine, 3-(dibutylamino)propylamine, 3-(methylamino)propylamine, 3-(dimethylamino)propylaminp, N-aminoethylethanolamine, N-aminoethylisopropanolamine, N-aminoethyl-N-methylethanolamine, diethylenetriamine, and triethylenetetramine, and more preferably selected from the group consisting of ethylenediamine, N,N,N',N'-tetramethylethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, 3-(diethylamino)propylamino, 3-(clibutylamino)propylamine, 3-(methylaminOpropylamine, 3-(dimethylamino)propylamine, N-aminoethylethanolamine, N-aminoethylisopropanolamine, and N-aminoethyl-N-methylethanolamine, from the viewpoint of reducing scratches and particles on a substrate surface after polishing. Further, the aliphatic amine compound is further preferably selected from the group consisting of N-aminoethylethanolamine, N-aminoethylisopropanolamine and N-aminoethyl-N-methylethanolamine, and still further preferably is N-aminoethylethanolamine from the viewpoints of reducing an amine smell and improving the solubility in water.

[0096] The alicyclic amine compound is preferably selected from the group consisting of piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 1-amino-4-methylpiperazine, N-methylpiperazine, 1(2-aminoethyllpiperazine and hydroxyethylpiperazine, more preferably selected from the group consisting of piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, N-methylpiperazine and hydroxyethylpiperazine, further preferably selected from the group consisting of piperazine, N-(2-aminoethyl)piperazine and hydroxyethylpiperazine, and still further preferably selected from the group consisting of N-(2-aminoethyl)piperazine and hydroxyethylpiperazine, from the viewpoint of reducing scratches and particles on a substrate surface after polishing.

[0097] Therefore, the aliphatic amine compound or alicyclic amine compound used in the polishing composition is still further preferably selected from the group consisting of N-aminoethylethanolamine, N-aminoethylisopropanol a in; ne, N-aminoethyl-N-methylethanolamine, piperazine, N-(2-aminoethyl)piperazine and hydroxyethylpiperazine, still further preferably selected from the group consisting of N-aminoethylethanolamine, N-(2-aminoethyDpiperazine and hydroxyethylpiperazine, and is still further preferably N-aminoethylethanolamine, from the viewpoint of reducing scratches and particles on a substrate surface after polishing, reducing an amine smell, and improving the solubility in water.

[0098] The content of the aliphatic amine compound or alicyclic amine compound in the polishing composition is preferably 0.001 to 10 mass%, more preferably 0.005 to 5 mass%, further preferably 0.008 to 2 mass%, still further preferably 0.01 to 1 mass%, still further preferably 0.01 to 0.5 mass%, and still further preferably 0.01 to 0.1 mass% with respect to the total mass of the polishing composition, from the viewpoint of reducing scratches and particles on a substrate surface after polishing. The polishing composition may contain one or two or more kinds of aliphatic or alicyclic amine compounds.

[0099] [Polishing method] The polishing composition obtained by the production method of the polishing composition of the present disclosure is supplied, for example, between organic polymer based polishing cloth (polishing pad) or the like of nonwoven fabric and a substrate to be polished, that is, the polishing composition is supplied to a substrate surface to be polished sandwiched by polishing boards with polishing pads attached thereto, and the polishing boards and/or the substrate are moved under a predetermined pressure, whereby the polishing composition is used in the polishing step while being in contact with the substrate. This polishing can remarkably suppress the occurrence of scratches and particles. Therefore, in another aspect, the present disclosure relates to a method of polishing a substrate, including steps of supplying the polishing composition of the present disclosure onto a surface to be polished of a substrate to be polished, contacting a polishing pad to the surface to be polished, and polishing the surface to be polished by moving the polishing pad and/or the substrate to be polished.

[0100] The polishing composition is particularly preferred for production of a substrate for a precision component. The polishing composition is suitable for polishing substrates of magnetic recording media such as a magnetic disk and a magneto-optical disk; and substrates for a precision component such as an optical disk, a photomask substrate, an optical lens, an optical mirror, an optical prism, and a semiconductor substrate. For producing a semiconductor substrate, the polishing composition obtained by the production method of the polishing composition of the present disclosure can be used in the step of polishing a silicon wafer (bare wafer), the step of forming a buried element separation film, the step of flattening an interlayer insulating film, the step of forming buried metal wiring, and the step of forming a buried capacitor.

[0101] Although the polishing composition of the present disclosure is particularly 15 effective in the polishing step, the polishing composition also can be applied similarly to, for example, other polishing steps such as a wrapping step.

[0102] Examples of a preferred material for an object to be polished, using the polishing composition of the present disclosure, include metals or semi-metals such as silicon, aluminum, nickel, tungsten, copper, tantalum, and titanium, or alloys thereof, glass materials such as glass, glass carbon, and amorphous carbon; ceramic materials such as alumina, silicon dioxide, silicon nitride, tantalum nitride, and titanium carbide; and resins such as a polyimide resin. Among these, objects to be polished containing metals such as aluminum, nickel, tungsten, and copper, and objects to be polished containing alloys that contain these metals as main components are preferred. For example, an aluminum alloy substrate plated with Ni-P, and glass substrates such as crystallized glass and tempered glass are more preferred, and an aluminum alloy substrate plated with Ni-P is further preferred.

[0103] There is no particular limitation on the shape of the object to be polished, and the polishing composition of the present disclosure is used in, for example, those which have a flat portion such as a disc shape, a plate shape, a slab shape, and a prism shape; and those which have a curved portion such as a lens. Among these, the polishing composition of the present disclosure is excellent in polishing a disc-shaped object to be polished.

[0104] [Production method of magnetic disk substrate] Therefore, in another aspect, the present disclosure relates to a method for producing a magnetic disk substrate, including a step of polishing a surface to be polished of a substrate to be polished by supplying the polishing composition obtained by the production method of the polishing composition of the present disclosure onto the surface to be polished. Further, in another aspect, the present disclosure relates to a method for producing a magnetic disk substrate, including steps of producing a polishing composition by the production method of the polishing composition of the present disclosure; and supplying the polishing composition onto the surface to be polished of the substrate to be polished, contacting a polishing pad to the surface to be polished, and polishing the surface to be polished by moving the polishing pad and/or the substrate to be polished.

[0105] Regarding the above*described embodiments, the present disclosure further 15 discloses the following compositions, production methods, or uses thereof: [0106] <1> A method for producing a polishing composition, including a step of filtering a raw silica dispersion containing colloidal silica with a filter containing a filter aid, wherein an average primary particle diameter of the colloidal silica as 20 determined by titration is 1 nm to 50 nm, and the filter aid has a hydroxyl group density of 0.40 x 10-5 mollm2 or more. <2> The method for producing a polishing composition according to <1>, wherein the average primary particle diameter of the colloidal silica as determined by titration is preferably 5.0 nm or more, more preferably 10.0 nm or more, further preferably 12.0 nm or more, and preferably 45 nm or less, more preferably 42 nm or less, and further preferably 40 nm or less.

<3> The method for producing a polishing composition according to <1> or <2>, wherein the filter aid, preferably diatomite, has a hydroxyl group density of preferably 0.41 x 10-5 mol/m2 or more, more preferably 0.43 x 10-5 mol/m2 or more, and preferably 2.0 x 10-5 mol/m2 or less, and more preferably 1.5 x 10-5 mol/m2 or less. <4> The method for producing a polishing composition according to any one of <1> to <3>, wherein the filter aid is obtained by mixing diatomite having a hydroxyl group density of less than 0.40 x 10-3 mol/m2 with an aqueous solution of acid, and thereafter subjecting the diatomite to a deoxidation treatment.

<5> The method for producing a polishing composition according to <4>, wherein an acid contained in the aqueous solution of acid is preferably at least one kind selected from the group consisting of hydrochloric acid, nitric add, phosphoric add, phosphonic add such as 1-hydroxyethylidene-1,1-diphosphonic acid, phosphinic acid, and organic acid having a pKa of less than 4, more preferably at least one kind selected from the group consisting of hydrochloric acid, nitric add, phosphoric acid, phosphonic acid, phosphinic acid, and organic acid having a pKa of less than 3.5, further preferably at least one kind selected from the group consisting of nitric acid, phosphoric acid, phosphonic acid, phosphinic acid, and organic acid having a pKa of 3.1 or less, and still further preferably at least one kind selected from the group consisting of phosphonic acid and phosphinic add.

<6> The method for producing a polishing composition according to any one of <1> to <5>, wherein a ratio of the average primary particle diameter of the colloidal silica as determined by titration to an average particle diameter of the filter aid as measured by a laser particle size distribution measuring device (average primary particle diameter of the colloidal silica as determined by titration / average particle diameter of the filter aid as measured by a laser particle sin:, distribution measuring device) is preferably 1.20 x 10-3 or more, more preferably 1.35 x 10-3 or more, further preferably 1.40 x 10-3 or more, still further preferably 1.42 x 10-3 or more, and preferably 4.20 x 10-3 or less, more preferably 3.80 x 10-3 or less, further preferably 3.00 x 10-3 or less, still further preferably 2.50 x 10-3 or less, still further preferably 2.00 x 10-3 or less, and still further preferably 1.50 x 10-3 or less.

<7> The method for producing a polishing composition according to any one of <1> to <6>, wherein the filter aid has a CV value of preferably 70% or more, more preferably 75% or more, further preferably 80% or more, still further preferably 85% or more, and preferably 100% or less, and more preferably 99% or less.

<8> The method for producing a polishing composition according to any one of 30 <1> to <7>, wherein the average particle diameter of the filter aid as measured by a laser particle size distribution measuring device is preferably 0.5 pm or more, more preferably 1 gm or more, further preferably 4.5 pm or more, still further preferably 8 pm or more, still further preferably 10 pm or more, and preferably 100 pm or less, more preferably 60 pm or less, further preferably 50 pm or less, still further preferably 40 pm or less, still further preferably 20 pm or less, and still further preferably 13 pm or less.

<9> The method for producing a polishing composition according to any one of <1> to <8>, wherein an average pore diameter of the filter aid as measured by a mercury intrusion method is preferably 0.1 to 3.5 pm, more preferably 0.1 to 3.0 pm, further preferably 0.1 to 2.7 pm, and still further preferably 0.1 to 2.6 pm.

<10> The method for producing a polishing composition according to any one of <1> to <9>, wherein an integrated pore volume of pores having a diameter of 0.15 pm or less of the filter aid as measured by a nitrogen adsorption method is preferably 0.3 mlig or more, more preferably 0.4 mLlg or more, further preferably 0 6 mug or more, and preferably 100.0 mL/g or less, more preferably 50 0 mL/g or less, and further preferably 10.0 mLig or less.

<11> The method for producing a polishing composition according to any one of <1> to <10>, wherein an integrated pore volume of pores having a diameter of 0.5 pm or less of the filter aid as measured by a mercury intrusion method is preferably 2.5 mLlg or more, more preferably 2.7 mL/g or more, further preferably 3.0 mL/g or more, still further preferably 4.0 mist or more, still further preferably 4.5 mlig or more, and preferably 1000 mL/g or less, more preferably 100 mlig or less, further preferably 50 mL/g or less, still further preferably 20 mLlg or less, and still further preferably 10 mUg or less.

<12> The method for producing a polishing composition according to any one of <1> to <11>, wherein a content of the colloidal silica in the raw silica dispersion is preferably 1 mass% or more, more preferably 10 mass% or more, further preferably 20 mass% or more, still further preferably 30 mass% or more, and preferably 50 mass% or less, more preferably 45 mass% or less, further preferably 43 mass% or less, and still further preferably 40 mass% or less.

<13> The method for producing a polishing composition according to any one of <1> to <12>, wherein a pH of the raw silica dispersion at 25°C is preferably 8.5 or more, more preferably 8.8 or more, further preferably 9.0 or more, and preferably 11 or less, more preferably 10.8 or less, and further preferably 10.5 or less.

<14> The method for producing a polishing composition according to any one of <1> to <13>, further including a step of mixing a silica dispersion obtained by the filtration of the raw silica dispersion with a mixture containing an acid, an oxidizer, and water.

<15> A polishing composition produced by the method for producing a polishing composition according to any one of <1> to <14>.

<16> The polishing composition according to <15>, further containing a water-soluble polymer having an anionic group, a heterocyclic aromatic compound, and an aliphatic amine compound or alicyclic amine compound.

<17> A method for producing a magnetic disk substrate, including a step of polishing a surface to be polished of a substrate to be polished by supplying the polishing composition obtained by the method for producing a polishing composition according to any one of <1> to <14> onto the surface to be polished.

<18> The method for producing a magnetic disk substrate according to <17>, 15 further including steps of producing a polishing composition by the method for producing a polishing composition; and supplying the polishing composition onto the surface to be polished of the substrate to be p o lished, contacting a polishing pad to the surface to be polished, and polishing the surface to be polished by moving the polishing pad and/or the substrate to be polished.

<19> A filter aid used in the method for producing a polishing composition according to any one of <1> to <14>, including diatomite having a hydroxyl group density of 0.40 x 10-5 mol/m2 or more, preferably 0.41 x 10-5 mol/m2 or more, more preferably 0.43 x 10-5 mol/m2 or more, and preferably 2.0 x 10-5 mollm2 or less, and more preferably 1.5 x 10-5 mol/m2 or less.

<20> A method for producing the filter aid according to <19>, including a step of mixing diatomite having a hydroxyl group density of less than 0.40 x 10-5 mol/m2 with an aqueous solution of acid, and thereafter subjecting the diatomite to a deoxidation treatment.

Examples

[0107] Hereinafter, the present disclosure will be described in more detail by way of examples, which are for illustrative purposes only. The present disclosure is not limited to these examples.

[0108] [Raw silica dispersion] The following slurries (Table 1) were used as the raw silica dispersion: colloidal silica slurry a (pH 9.0, manufactured by JGC Catalysts and Chemicals Ltd., the average primary particle diameter 18.0 nm, the concentration of silica particles 40 mass%); colloidal silica slurry b (pH 10.0, manufactured by JGC Catalysts and Chemicals Ltd., the average primary particle diameter 50.0 nm, the concentration of silica particles 40 mass%); and colloidal silica slurry c (pH 10.0, manufactured by JGC Catalysts and Chemicals Ltd., the average primary particle diameter 100.0 nm, the concentration of silica particles 4() mass%). The average primary particle diameters of colloidal silica in the raw silica dispersion and the polishing composition, and the 0.45 pna filter liquid passing quantity were measured as below.

[0109] [Method for measuring average primary particle diameter of colloidal silica] First, 1.5 g (solid content) each of the colloidal silica slurries was collected in a 200 mL beaker, and 100 mL of ion exchange water was added thereto, followed by mixing with a stirrer to obtain each mixture. Next, the pH of the mixture was adjusted to 3.0 with a 0.1 mol/L hydrochloric add standard solution using a potentiometric titrator. 30.0 g of sodium chloride was added to the pH-adjusted mixture and dissolved therein with a stirrer. Ion exchange water was added thereto up to a 150 mL reference line of the beaker, followed by mixing with a stirrer. The obtained sample solution was soaked in a constant temperature water tank (20 f 2°C) for about 30 minutes. The sample solution was titrated with a 0.1 mol/L sodium hydroxide standard solution using the potentiometric titrator, and an amount (g) (A) of the sodium hydroxide standard solution used to change the pH of the sample solution from 4.0 to 9.0 was read. Meanwhile, a blank test in which the colloidal silica slurry was not placed in a 200 mL beaker was performed, and an amount (g) (B) of the sodium hydroxide standard solution required for titration in the blank test was read. Then, an average particle diameter (rim) was calculated by the following formula.

Average particle diameter (nm) = 3100 ÷ 26.5 x (A-B) ÷ collected amount of sample (g) The collected amount of sample: colloidal silica slurry (solid content) 1.5 g [0110] [Table 1] Colloidal silica Average primary particle Manufacturer diameter (nm) a 18 JGC Catalysts and Chemicals Ltd. b 50 JGC Catalysts and Chemicals Ltd. c 100 JGC Catalysts and Chemicals Ltd. [0111] [Filteraid containing filter] Filteraid containing filters were produced as described below, using commercially available filter aids A-C (see Table 2 below). The filter aids A-C and filter aids 1-16 obtained by subjecting the filter aids A-C to a heat treatment or add treatment were measured for the laser average particle diameter, the CV value, the integrated pore volume, and the hydroxyl group density using the following methods.

Table 2 shows the above-described parameters of the filter aids A-C. Among the above-described parameters of the filter aids 1-16, the laser average particle diameter, the CV value, the integrated pore volume, the average pore diameter were the same as those of the filter aids before treatment with an aqueous solution of add or the like. The hydroxyl group densities of the filter aids A-C and the filter aids 1-16 are shown in Tables 2, 4 to 7. The average pore diameters in Table 2 are catalogue values. [0112] [Method for measuring laser average particle diameter of filter aid] A value obtained as a volume-based median diameter obtained by measuring each filter aid with a laser diffraction-scattering type particle size distribution analyzer (trade name: LA-920, manufactured by Horiba Ltd.) was defined as a laser average particle diameter.

[0113] [Method for measuring CV value of filter aid] A percentage of value obtained by dividing an arithmetic standard deviation obtained by measuring each filter aid with a laser diffraction-scattering type particle size distribution analyzer (trade name: LA-920, manufactured by Horiba Ltd.) by the value obtained as a volume-based median diameter was defined as a CV value N. [0114] [Method for measuring integrated pore volume of 0.15 pm or less] An integrated pore volume of pores having a diameter of 0.15 pm or less of a filter aid was measured by a nitrogen adsorption method. Specifically, about 1 g of each precisely weighed filter aid was set in ASAP2020 (Specific surface area * Pore distribution measurement device, manufactured by Shimadzu Corporation), and a total of pore volumes of pores having a diameter of 0.15 pm or less obtained by a Halsey system of a BJH method from a nitrogen adsorption isotherm was defined as an integrated pore volume of 0 15 pm or less. The pretreatment of a sample was performed by placing the sample in a baking furnace (trade name: SK-2535E, manufactured by Motoyama Co., Ltd.), raising the temperature of the baking furnace to 100°C at 10°C/min, and keeping 100°C for 2 hours. Further, the inside of the baking furnace was degassed at 60°C so that the pressure would be 500 mmHg. [0115] [Method for measuring integrated pore volume of 0 5 pm or less] About 0.1 g to 0.3 g of each filter aid was precisely weighed with a balance, and placed in a 5 cc powder measurement cell washed well with hexane so that the filter aid would not adhere to the inside of a stem or a frosted part, and the cell was set in AutoPore IV-9500 (mercury intrusion method, pore distribution measurement device, manufactured by Shimadzu Corporation). Next, an application (AutoPore IV-9500 ver 1.07) was started up with a personal computer, and requirements were input to Sample Information (weight of a filter aid measured in advance), Analysis Condition (select Standard), Penetrometer Property (cell weight), and Report condition (select Standard), whereby measurement was performed. The measurement was performed in the order of a low-pressure portion and a high-pressure portion, and automatically, results of a Log Differential Pore Volume (mL/g) with respect to Median Pore Diameter (Volume) (pm) and each Pore Size Diameter (pm) were obtained.

[0116] (1) Measurement condition Measurement Cell: 5cc-Powder (08-0444), manufactured by Micromeritics 25 Instrument Corporation Measurement System: Pressure control system (pressure table mode) Low Pressure Equilibrium Time: 5 secs High pressure Equilibrium Tune: 5 secs Parameters regarding Hg: contact angle: 130°, surface tension: 485 dynes/cm Stem Volume Used: sample amount is adjusted to be equal to or less than 100% (about 50%) [0117] (2) Method for calculating integrated pore volume of 0.5 pm or less A value obtained by integrating Log Differential Pore Volumes (nil /0 of 0.5 pm or less was defined as an integrated pore volume of pores having a diameter of 0.5 pm or less.

[0118] [Method for measuring hydroxyl group density of filter aid] A value obtained by dividing the number of hydroxyl groups per 1 g obtained by the below-mentioned measurement method by a surface area of a filter aid per 1 g obtained by the below-mentioned method was defined as a hydroxyl group density of the filter aid.

[0119] (1) Method for measuring the number of hydroxyl groups of filter aid * Potentiometric measurement device: potentiometric automatic titrator "AT-310J", manufactured by Kyoto Electronics Manufacturing Co., Ltd. * Titration reagent: 0.01 N hydrochloric acid aqueous solution * Dropping speed of titration reagent: 0.03 m]Jmin * Measurement sample: a measurement sample was prepared by diluting a 15 filter aid with an NaOH solution so that the density of the filter aid would be 02 wt%. [0120] (2) Method for measuring surface area of filter aid A surface area of a filter aid was measured by a nitrogen adsorption method. Specifically, about 1 g of each precisely weighed filter aid was set in ASAP2020 (Specific surface area * Pore distribution measurement device, manufactured by Shimadzu Corporation), and a value obtained by a Halsey system of a BJH method from a nitrogen adsorption isotherm was defined as a surface area.

[0121] [Table 2]

Type of Laser Average cw Integrated Integrated Hydroxyl Product name Manufacturer filter average Pere value N pore pore volume of 0.5 pm or group aid * diameter volume of less density particle / .., 0.15 pm (ml/g) (x 10 diameter kitna, or leas mol/m2) (pm) (in T ig,) A 12.6 2.6 78 0.6 4.6 0.38 Celpure300 SIGMA-ALDRICH CO. LLC.

B 12.7 2.3 86 0.6 5.1 0.39 CelpureP65 SIGMA-ALDRICH CO. LLC.

C 15.7 2.7 73 0.5 5.2 0.37 Radiolite (registered trademark) No. 100 Showa Chemical Industry [0122] [Method of controlling OH group density] The OH group density was controlled by subjecting the filter aids A-C to the following heat treatment or acid treatment.

[0123] (1) Heat treatment A filter aid was placed in a baking plate, and baked using a baking furnace (trade name: SK-2535E, manufactured by Motoyama Co., Ltd.). Specifically, the baking plate with the filter aid was placed in the baking furnace set at 25°C inside, the internal temperature of the furnace was increased to 800°C for 10 hours while causing airflow (3L/min), and the filter aid was baked for more 5 or 10 hours under an atmosphere of 800°C.

[0124] (2) Acid treatment 'lb 50 g of each filter aid, 150 ml of each of aqueous solutions of acid (a to t) shown in Table 3 below was added, and stirred and mixed sufficiently. The mixture was left to stand for time (treatment time) indicated in Table 3 after stopping the stirring, and then a supernatant was removed from the mixture. Ion exchange water was added to the mixture from which the supernatant was removed, and stirred for 5 minutes with a stirrer. The stirred mixture was left to stand until a supernatant became transparent, followed by removal of the supernatant and washing of the filter aid. This operation was repeated until the supernatant neutralized (p1-1 = 5 to 8). Lastly, the filter aid was filtered on filter paper and dried naturally. Thus, an acid-treated filter aid was obtained.

[0125] [Table 3]

Aqueous Acid Manufacturer Concentration (mol/L) 0 Treatment time (10 solution ofacid a Hydrochloric acid Wako Pure Chemical Industries, Ltd. 0.3 48 b Oxalic acid SIGMA-ALDRICH CO. TIC. 0.3 48 c Citric acid Wako Pure Chemical Industries, Ltd. 0.3 48 d Phosphinic acid Wako Pure Chemical Industries, Ltd. 0.3 48 e Nitric acid Wako Pure Chemical Industries, Ltd. 0.3 48 f Phosphoric acid Wako Pure Chemical Industries, Ltd. 0.3 48 g Malonic acid Wako Pam Chemical Industries, Ltd. 0.3 48 h Malic acid Wako Pure Chemical Industries, Ltd. 0.3 48 i HEDP Italmatch Japan Ltd. 0.3 48 j Sulfuric acid TAYCA Corporation 0.3 48 k Succinic acid Wako Pure Chemical Industries, Ltd. 0.3 48 1 Acetic acid Wako Pure Chemical Industries, Ltd. 0.3 48 m Phosphoric acid Wako Pure Chemical Industries, Ltd. 0.1 48 n Phosphoric acid Wako Pure Chemical Industries, Ltd. 0.2 48 o Citric acid Wako Pure Chemical Industries, Ltd. 0.1 48 P Citric acid Wako Pure Chemical Industries, Ltd. 0.2 48 q Swrinie add Wako Pure Chemical Industries, Ltd. 0.6 48 r Succinic acid Wako Pure Chemical Industries, Ltd. 1.5 48 a Acetic acid Wako Pure Chemical Industries, Ltd. 0.6 48 t Acetic acid Wako Pure Chemical Industries, Ltd. 1.5 48 1) The concentration of acid in the aqueous solution of acid [0126] [Production of filter containing filter aid] 100 mL of ion exchange water was added to 10 g of the acid-treated filter aid, followed by stirring and mixing, whereby an aqueous solution dispersed with filter aid was obtained. Next, filter paper (No. 5A (opening 7 jun), manufactured by Advantec Co., Ltd.) was set in a 90 mm4i plate-type SUS housing (INLET 90-TL, manufactured by Sumitomo 3M limited (currently 3M Japan limited)), and the aqueous solution dispersed with filter aid was filtered under a pressure of 0.1 MPa or less to form a uniform cake layer of the filter aid on the filter paper. After that, the cake layer was washed with 1 to 2 L of ion exchange water so as to obtain a filter containing a filter aid. The content of the filter aid in the filter-aid containing filter was 0.18 g/cm2. [0127] [Filtration] [Condition for filtering raw silica dispersion: Examples 1-18 and Comparative Examples 1-17] Each of the raw silica dispersions (colloidal silica slurries a to c) was filtered with the thus produced filter-aid containing filter which remained wet with washing water without being dried, under a filtration pressure of 0.30 MPa at a filtration flow rate of 34.6 g/(min * m2) to obtain silica dispersions to be used for polishing compositions. 'rabies 4-7 show the pH of the silica dispersions at 25°C.

[0128] [Method for measuring 0.45 pm filter liquid passing quantity] The silica dispersion obtained by the above-described filtration was passed through a predetermined filter (hydrophilic PTFE 0.45 (pore diameter) pm filter, type: 25HP045AN, manufactured by Advantec Co., Ltd.) under a predetermined pressure (air pressure: 0.25 MPa), and a liquid passing quantity (ml) until clogging of the filter was measured as a MF value. Tables 4-7 show the MF values. The 0.45 pm filter liquid passing quantity under these conditions can be an index indicating the capability of the silica dispersion to reduce scratches in the case of using the silica dispersion for preparing the polishing composition. In other words, a larger MF value can be evaluated as the silica dispersion or polishing composition capable of reducing scratches.

[0129] [Method for preparing finish polishing composition] lb ion exchange water, 0.1 mass% of 1H-benzetriazole sodium salt, 0.03 mass% of N-aminoethylethanolamine, 0.02 mass% of sodium salt of acrylic acid/acrylamide-2-methylpropanesulfonic add copolymer (anionic polymer, molar ratio: 90/10, weight average molecular weight: 2000, manufactured by TOAGOSEI Co., Ltd.), 0.4 mass% of sulfuric acid, 0.05 mass% of 1-hydroxyethylidene-1,1-diphosphonic acid, and 0.4 mass% of hydrogen peroxide were added and mixed. While stirring the obtained aqueous solution, a silica dispersion filtered using a filter containing the filter aid was added thereto so that the silica concentration in the polishing composition would be 5 mass%. Thus, polishing compositions of Examples 1-18 and Comparative Examples 1-17 were prepared (pH 1.0-2.0 (25°C)).

[0130] [Method for measuring weight average molecular weight of anionic polymer] The weight average molecular weight of the anionic polymer was measured by gel permeation chromatography (GPC) under the following measurement conditions.

(GPC Conditions) Column: TSKge1 G4000PWXL + TSKge1 G2500PWXL (manufactured by lbsoh Corporation) Guard column: TSKguard Column PWXL (manufactured by lbsoh Corporation) Eluent: 0.2M phosphate buffer/CHgCN = 9/1 (volume ratio) Ibmperature: 40°C Flow Speed: 10 mumin Sample Size: 5 mg/mL Detector: RI Standard for Calculation: sodium polyacrylate (molecular weight (Mp): 115,000; 28,000; 4,100; 1,250 (manufactured by Sowa Science Corporation and American Polymer Standards Corporation)) [0131] [Polishing of substrate using polishing composition] Finish polishing was performed under the following conditions, using the polishing compositions of Examples 1-18 and Comparative Examples 1-17 prepared as described above. The number of scratches on the substrates after polishing was evaluated. Tables 4-7 below show the results. As the substrate to be polished, an aluminum alloy substrate plated with Ni-P having an AFM-Ra of 5 to 15 A, a thickness of 127 mm, an outer diameter of 95 mmO, and an inner diameter of 25 mmO, roughly polished with a polishing liquid containing an alumina abradant in advance, was used.

[0132] [Finish polishing condition] * Polishing test machine: double-sided 9B polisher, manufactured by SpeedFam Co, Ltd. * Polishing pad: urethane-finished polishing pad, manufactured by Fujibo Holdings, Inc. * Number of revolutions of an upper surface plate: 32.5 rpm/min * Polishing composition supply amount: 100 mumin * Main polishing time: 4 minutes * Main polishing load: 7.8 kPa * Number of placed substrates: 10 [0133] [Condition for measuring scratches] * Measurement devices Optical surface analyzer (Candela OSA6100, manufactured by KLA-Thncor 5 Corporation) Atomic force microscope (DI Nano-Scope HI, manufactured by Veeco * Measurement method: Substrates after polishing were soaked in ion exchange water for 5 minutes, and rinsed for 20 seconds with ion exchange water. Then, of the substrates placed in a polishing test machine, four substrates were selected at random, and each substrate was irradiated with a laser at 10,000 rpm for detecting flaws having a length of 100 pm or more on the substrate surface using the optical surface analyzer. Among these flaws, those having a depth of 1 nm or more and less than 100 nm, and a width of 5 nm or more and less than 500 nm observed using the atomic force microscope were counted as scratches. The total number of scratches (lines) on both surfaces of the respective four substrates was divided by 8 to calculate the number of scratches per substrate surface. Tables 4-7 show the results. [0134] [Table 4] Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Ex. 12 Abrasive grain Number a a a a a a a a a b a a Average primary 18 18 18 18 18 18 18 18 18 50 18 18 particle diameter (nm) Filter aid Number" A (1) A (4) A (9) A (10) A (11) A (12) A (2) A (3) A (13) A (2) B (5) B (6) Treating agent Hydrochloric PlicsPhillic Nitric Phosphoric Malcnic Malk acid Oxalic acid Citric acid HEDP Oxalic acid Oxalic Phosphinic add acid acid acid acid acid acid piCa (25°C, ionic - - - 1.83 2.6 3.4 1.3 3.1 1.4 1.3 1.3 -strength 0.1) Concentration 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 (mon) of acid (treating agent) in aqueous solution of acid Hydroxyl group 0.41 0.43 0.42 0.42 0.41 0.41 0.44 0.42 0.43 0.44 0.42 0.41 density (x 10-5 mol/m2) Average particle diameter ratio (silica/filter aid) 1.43 1.43 1.43 1.43 1.43 1.43 1.43 1.43 1.43 3.97 1.42 1.42 (x 10-3)*2 Silica dispersion pH (25°C) 9.0 9.0 9.0 9.0 9.0 9.0 9.0 9.0 9.0 10.0 9.0 9.0 1 I MF value (0.45 am 247 244 210 234 264 211 297 284 333 193 254 231 filter liquid passing quantity (g)) The number of 6 6 7 7 6 7 7 7 5 10 9 9 scratches *1) The number in parenthesis indicates the number after acid or heat treatment.

*2) Ratio (average primary particle diameter of colloidal silica as determined by titration / average particle diameter of filter aid as measured by laser particle size distribution measuring device) *EL: Example co co

[0135] [Table 5]

Cora. Ex. 1 Cora. Ex. 2 Com. EL 3 Com. Ex. 4 Cora. Ex. 5 Com. Ex. 6 Cora. Ex. 7 Coro. Ex. 8 Com Ex. 9 Cora Ex. 10 Corn. Ex. 11 Number a a a a a a c c c a a 1 I Average primary 18 18 18 18 18 18 100 100 100 18 18 particle diameter (nm) Filter aid Nurnberg A A (7) A (8) A (14) A (15) A (16) A A (1) A (2) B C Treating agent or None 800°C*2) 800°C*2) Sulfuric Succinic acid Acetic None Hydrochloric acid Oxalic None None treatment method 511'31 101173) acid acid acid pKa (25°C, ionic - - - - 4.0 4.5 - - 1.3 - -strength 0.1) Concentration (mollL) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 of acid (treating agent) in aqueous solution of acid Hydroxyl group density 0.38 0.27 0.27 0.39 0.38 0.38 0.38 0.41 0.44 0.36 0.37 (x 10-5mollm2) Average particle diameter ratio (silica/filter aid) (x 10-3)g 1.43 1.43 1.43 1.43 1.43 1.43 7.94 7.94 7.94 1.42 1.15 Silica dispersion pH (25°C) 9.0 9.0 9.0 9.0 9.0 9.0 10.0 10.0 10.0 9.0 9.0 1. ME value (0.45 pm 147 117 105 144 166 138 2 3 2 127 130 dpa;sing filter liquid quantity ( The number of 14 21 22 19 16 21 41 42 39 17 19 scratches *1) The number in parenthesis indicates the number after acid or heat treatment.

*2) Atmosphere temperature inside baking furnace *3) baking time *4) Ratio (average primary particle diameter of colloidal silica as determined by titration / average particle diameter of filter aid as measured by laser particle size distribution measuring device) * Corn. Ex.: Comparative Example

[0136] [Table 6]

Ex. 13 Ex. 14 Ex. 15 Ex. 16 Ex. 17 Ex. 18 i g Number a a a a a a a Average primary particle 18 18 18 18 18 18 diameter (nm) g Number'' A(10) A(10) A(10) A(3) A(3) A(3) Treating agent Phosphoric add Phosphoric acid Phosphoric add Citric acid Citric add Citric acid pKa (25°C, ionic strength 0.1) 1.83 1.83 183 3.1 3.1 3.1 Concentration (mol/L) of 0.1 0.2 0.3 0.1 0.2 0.3 acid (treating agent) in aqueous solution of acid Hydroxyl group density 0.4 0.42 0.42 0.41 0.42 0.42 6c 10-5md/m2) Average particle diameter ratio 1.43 1.43 1.43 1.43 1.43 1.43 (silica/filter aid) (x 10-3y2 Silica dispersion pH (25°C) 9.0 9.0 9.0 9.0 9.0 9.0 1 I MF value (0.45 ism filter 209 229 234 243 277 284 liquid passing quantity (g)) The number of scratches 8 8 7 8 8 7 *1) The number in parenthesis indicates the number after acid or heat treatment *2) Ratio (average primary particle diameter of colloidal silica as determined by titration / average particle diameter of filter aid as measured by laser particle size distribution measuring device) *Ex.: Example

[0137] [Table 7]

Cora. Ex. Com. Ex. Cora. Ex. Cora. Ex. Cora. Ex. Cora. Ex.

12 13 14 15 16 17 i g Number a a a a a a Average primary parts le 18 18 18 18 18 18 diameter (rim) ed T" S Nurnberg A(15) A(15) A(15) A(16) A(16) A(16) 1.7 fr., Treating agent Suecinie ackl Succinic acid Suoinic add Acetic acid Acetic acid Acetic acid pKa (25°C, ionic strength 0.1) 4.0 4.0 4.0 4.5 4.5 4.5 Concentration (mol/L) of 0.3 0.6 1.5 0.3 0.6 1.5 add (treating agent) in aqueous solution of acid Hydroxyl group density 0.38 0.38 0.39 0.38 0.38 0.38 (x 10-5mol/m2) Average particle diameter ratio 1.43 1.43 1.43 1.43 1.43 1.43 (silica/filter aid) (a 10-3)'2 Silica dispersion pH (25°C) 9.0 9.0 9.0 9.0 9.0 9.0 1 i liciMFuidvpaluent..4q5 imitifiltytewr) 166 172 169 138 141 144 lit The number of scratches 16 15 15 21 20 20 *1) The number in parenthesis indicates the number after acid or heat treatment.

*2) Ratio (average primary particle diameter of colloidal silica as determined by titration / average particle diameter of filter aid as measured by laser particle size distribution measuring device) * Com. Ex.: Comparative Example [0138] As shown in Tables 4-7 above, Examples 1-18 in which diatomite had a hydroxyl group density of 0.40 x 10-5 mol/m2 or more and the average primary particle diameter of the colloidal silica was 1 nm to 50 nm resulted in higher MF values and less number of scratches than Comparative Examples 1-17.

Industrial Applicability

[0139] As explained above, according to the present disclosure, coarse particles and gelled substances in a raw silica dispersion containing colloidal silica can be removed effectively through high-precision filtration, and thus it is possible to produce a polishing composition that can reduce the number of scratches on a substrate surface after polishing. Therefore, the production method of the polishing composition of the present invention can enhance productivity of substrates such as magnetic disk substrates.