JP2016015184A - Magnetic disk substrate polishing liquid composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic disk substrate polishing liquid composition capable of reducing long period defect of a roughly polished substrate surface.SOLUTION: In one aspect, a magnetic disk substrate polishing agent composition includes non-spherical silica particles, a nitrogen-containing compound, acid, oxidant, and water, and is characterized in that (1) the non-spherical silica particle is in the form of two or more particles aggregated or fused, (2) the non-spherical silica particle has a ΔCV value of more than 0.0% and less than 10%, (3) a ratio (D1/D2) of volume average particle diameter (D1) obtained by a dynamic light scattering method to specific surface conversion particle diameter (D2) by a BET method, of the non-spherical silica particle, is 2.00 or more and 4.00 or less, (4) the nitrogen-containing compound is aliphatic amine compound or alicyclic amine compound that contains two to five nitrogen atoms in molecule, (5) the acid is selected from the group consisting of phosphoric acids, phosphonic acid, organic phosphonic acid, and a combination thereof, and (6) pH is 1.4 or more and 2.5 or less.

Description

  The present disclosure relates to a polishing composition for a magnetic disk substrate, a method for polishing a magnetic disk substrate, and a method for manufacturing a magnetic disk substrate.

  In recent years, magnetic disk drives have been reduced in size and capacity, and high recording density has been demanded. Therefore, it is necessary to improve the detection sensitivity of high recording density magnetic signals, and technical development is underway to reduce the flying height of the magnetic head and reduce the unit recording area. The magnetic disk substrate is designed to improve the smoothness and flatness (reduction of surface roughness, waviness and edge sag) and to reduce surface defects (residual abrasive grains and scratches) in order to reduce the flying height of the magnetic head and ensure the recording area. , Reduction of protrusions, pits, etc.) is strictly demanded. From the viewpoint of achieving both improvement in surface quality and productivity, such as smoother and less scratches, such a requirement, the hard disk substrate manufacturing method includes a multi-stage polishing method having two or more polishing steps. Often adopted. In general, in the final polishing step of the multi-stage polishing method, that is, the final polishing step, a polishing composition for finishing that contains colloidal silica particles in order to satisfy the requirements of reducing surface roughness and scratches such as scratches, protrusions, and pits. In the polishing step (also referred to as rough polishing step) prior to the final polishing step, a polishing liquid composition containing alumina particles is used from the viewpoint of improving productivity. However, when alumina particles are used as the abrasive, media drive defects may be caused by the piercing of the alumina particles into the substrate.

  Therefore, a method of manufacturing a magnetic disk substrate that can reduce the sticking of particles to the substrate by using a polishing composition containing no alumina particles and using silica particles as abrasive grains in the rough polishing step has been proposed. (Patent Document 1).

  On the other hand, by adding an amine compound as an additive of the polishing liquid composition, improvement in cleanliness in glass hard disk substrate polishing and durability in cyclic polishing (Patent Document 2), reduction of protrusion defects and scratches (patent) Reference 3) has also been attempted. Moreover, phosphoric acid and phosphonic acid may be used as the acid of the polishing composition (Patent Documents 4 and 5).

  As a surface defect of a magnetic disk substrate using a Ni-P plated alumina alloy substrate, there is PED (polish-enhanced defects). PED is caused by corrosion pits at the time of Ni-P plating film formation (Patent Document 6). PED is also called “long-period defect” of a magnetic disk substrate together with a grind scratch.

JP 2014-29754 A JP 2012-12469 A JP 2011-131346 A JP 2003-147337 A JP 2008-166329 A Special table 2012-46712 gazette

  If a rough polishing process and a final polishing process that do not use alumina particles are employed in the polishing process of the magnetic disk substrate, residual alumina (for example, alumina adhesion, alumina sticking) can be eliminated, thereby reducing projection defects. However, it has been found that when a rough polishing process is performed with silica particles instead of alumina particles, a problem that long-period defects cannot be removed newly occurs. In the case of performing the rough polishing process with alumina particles, the problem of long-period defects generally does not occur. Since the removal rate of long-period defects is highly correlated with the substrate yield, further improvement in the removal rate of long-period defects is desired in rough polishing.

  Patent Document 1 discloses that if rough polishing is performed using non-spherical silica particles defined by predetermined parameters as abrasive grains, the polishing time for rough polishing is greatly prolonged even when alumina particles are substantially not included. Disclosed is that long-wave waviness after rough polishing can be reduced without doing so. However, for long-period defects, further improvement in removal rate is desired.

  Therefore, in one or a plurality of embodiments, the present disclosure reduces long-period defects on the substrate surface after rough polishing without significantly impairing the polishing speed in rough polishing using non-spherical silica particles as abrasive grains. Provided is a polishing composition for a magnetic disk substrate.

In one or a plurality of embodiments, the present disclosure is an abrasive composition for a magnetic disk substrate containing non-spherical silica particles A, a nitrogen-containing compound, an acid, an oxidizing agent, and water,
(1) The non-spherical silica particle A has a shape in which two or more particles are aggregated or fused,
(2) The ΔCV value of the non-spherical silica particles A is more than 0.0% and less than 10%,
Here, the ΔCV value is obtained by dividing the standard deviation based on the scattering intensity distribution at a detection angle of 30 ° by the dynamic light scattering method by the average particle diameter based on the scattering intensity distribution and multiplying by 100 (CV30). The difference (ΔCV = CV30−CV90) from the value obtained by dividing the standard deviation based on the scattering intensity distribution at an angle of 90 ° by the average particle diameter based on the scattering intensity distribution and multiplying by 100 (CV90),
(3) The ratio (D1 / D2) of the volume average particle diameter (D1) by the dynamic light scattering method of the non-spherical silica particles A to the specific surface area equivalent particle diameter (D2) by the BET method is 2.00 or more. 00 or less,
(4) The nitrogen-containing compound is an aliphatic amine compound or an alicyclic amine compound having a nitrogen content in the molecule of 2 to 5,
(5) the acid is selected from the group consisting of phosphoric acids, phosphonic acids, organic phosphonic acids, and combinations thereof;
(6) The present invention relates to a magnetic disk substrate abrasive composition having a pH of 1.4 or more and 2.5 or less.

In another aspect, the present disclosure provides:
(1) The process of grind | polishing the grinding | polishing target surface of a to-be-polished board | substrate using the polishing liquid composition which concerns on this indication,
(2) a step of cleaning the substrate obtained in step (1), and
(3) It has the process of grind | polishing the grinding | polishing object surface grinding | polishing object surface of the board | substrate obtained by process (2) using the polishing liquid composition containing a silica particle,
The steps (1) and (3) relate to a magnetic disk substrate polishing method / manufacturing method performed by another polishing machine.

  The polishing composition according to the present disclosure can significantly reduce the protrusion defects after rough polishing and after final polishing when alumina particles are not used. In addition, according to the polishing liquid composition according to the present disclosure, in one or a plurality of embodiments, there is an effect that long-period defects on the substrate surface after rough polishing can be reduced without greatly impairing the polishing rate in rough polishing. Can be done.

FIG. 1 is an example of an electron microscope (TEM) observation photograph of deformed colloidal silica abrasive grains. FIG. 2 is an example of an electron microscope (TEM) observation photograph of a confetti-type colloidal silica abrasive grain. FIG. 3 is a graph showing the volume particle size distribution. FIG. 4 is an example of a result obtained by measuring a substrate surface having a long-period defect (PED) with an optical interference type surface shape measuring machine. FIG. 5 is a diagram illustrating an embodiment of a polishing system.

  The present disclosure relates to a rough polishing step using a polishing liquid composition containing predetermined non-spherical silica particles as abrasive grains, and a predetermined nitrogen-containing compound and a predetermined acid (phosphoric acid or phosphonic acid) are added to the polishing liquid composition. The addition is based on the knowledge that the removal rate of long-period defects is improved and the polishing rate is not greatly impaired. Generally, in the manufacture of a magnetic disk substrate, if long-period defects can be reduced, the substrate yield is improved. Therefore, according to the present disclosure, in one or a plurality of embodiments, the substrate yield can be improved while maintaining the productivity in the manufacture of the magnetic disk substrate.

  Although the details of the mechanism by which the removal rate of long-period defects is improved by a combination of a predetermined non-spherical silica particle, a predetermined nitrogen-containing compound, and a predetermined acid are not clear, it is presumed as follows. That is, the predetermined nitrogen-containing compound is bonded to both the silica particles and the substrate (for example, a Ni—P plated aluminum alloy substrate), and improves the adsorptivity of the silica particles to the substrate. Thereby, the contact frequency of the silica particles to the substrate is increased, the polishing rate is improved, and the removal rate of long-period defects is considered to be improved. Furthermore, the presence of phosphoric acid or phosphonic acid is considered to improve the reduction efficiency of long-period defects, particularly PED, with a small amount of polishing due to the corrosion inhibiting effect of phosphoric acid or phosphonic acid. In particular, in the present disclosure, by using silica particles having a specific shape, the effect of suppressing surface defects and the effect of suppressing corrosion work synergistically, and the substrate is excellent in suppressing defects. However, the present disclosure need not be construed as being limited to these mechanisms.

That is, in one aspect, the present disclosure is an abrasive composition for a magnetic disk substrate containing non-spherical silica particles A, a nitrogen-containing compound, an acid, an oxidizing agent, and water,
(1) The non-spherical silica particle A has a shape in which two or more particles are aggregated or fused,
(2) The ΔCV value of the non-spherical silica particles A is more than 0.0% and less than 10%,
Here, the ΔCV value is obtained by dividing the standard deviation based on the scattering intensity distribution at a detection angle of 30 ° by the dynamic light scattering method by the average particle diameter based on the scattering intensity distribution and multiplying by 100 (CV30). The difference (ΔCV = CV30−CV90) from the value obtained by dividing the standard deviation based on the scattering intensity distribution at an angle of 90 ° by the average particle diameter based on the scattering intensity distribution and multiplying by 100 (CV90),
(3) The ratio (D1 / D2) of the volume average particle diameter (D1) by the dynamic light scattering method of the non-spherical silica particles A to the specific surface area equivalent particle diameter (D2) by the BET method is 2.00 or more. 00 or less,
(4) The nitrogen-containing compound is an aliphatic amine compound or an alicyclic amine compound having a nitrogen content number of 2 to 5 in the molecule,
(5) the acid is selected from the group consisting of phosphoric acids, phosphonic acids, organic phosphonic acids, and combinations thereof;
(6) The present invention relates to a magnetic disk substrate abrasive composition (hereinafter also referred to as “a polishing composition according to the present disclosure”) having a pH of 1.4 or more and 2.5 or less. According to the polishing composition according to the present disclosure, in one or a plurality of embodiments, protrusion defects after rough polishing and after final polishing can be greatly reduced without greatly impairing the polishing rate in rough polishing, and rough polishing can be performed. An effect that long-period defects on the substrate surface after polishing can be reduced can be achieved.

  In the present disclosure, the “long-period defect” includes a grind scratch and a PED (polish enhanced defect) generated in the manufacturing process of the Ni—P plated aluminum substrate. Grind scratches refer to grinding marks on a grindstone in a process of grinding an aluminum substrate before plating (grinding process). PED refers to a portion of insufficient annealing caused by water or foreign matter adhering to the substrate surface in the annealing step in the plating process on the alumina substrate, and occurs as a shallow dent defect on the substrate surface during polishing. In one or a plurality of embodiments, the long-period defect can be measured using the measuring device described in the examples.

[Non-spherical silica particles A]
The polishing liquid composition according to the present disclosure contains non-spherical silica particles A. Examples of the non-spherical silica particles include colloidal silica, fumed silica, and surface-modified silica. From the viewpoint of reducing long-period defects without significantly degrading the polishing rate, colloidal silica is preferable, and colloidal silica having the following specific shape is more preferable. In addition, the non-spherical silica particles may be produced by a flame melting method or a sol-gel method from the viewpoint of reducing long-period defects without significantly reducing the polishing rate. Silica particles produced by a particle growth method) are preferred.

[Shape of non-spherical silica particle A]
The shape of the non-spherical silica particles A is a shape in which a plurality of particles (for example, two or more particles) are aggregated or fused from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. In one or a plurality of embodiments, the non-spherical silica particles A are selected from the group consisting of confetti-type silica particles A1, deformed-type silica particles A2, and deformed and confetti-type silica particles A3. At least one type of silica particles is preferable, and irregular-shaped silica particles A2 are more preferable.

  In the present disclosure, the gold-peeled silica particle A1 refers to a silica particle having unique hook-shaped protrusions on the surface of a spherical particle in one or a plurality of embodiments (see FIG. 2). In one or a plurality of embodiments, the silica particle A1 has a shape in which two or more particles different in particle size by 5 times or more are aggregated or fused on the basis of the particle size of the smallest silica particle. Preferably, the small particles are partially embedded in the large particles. The particle diameter can be obtained as the equivalent circle diameter measured in one particle in an electron microscope (TEM or the like) observation image, that is, the major axis of an equivalent circle having the same area as the projected area of the particle. The particle diameter in silica particle A2 and silica particle A3 can be similarly determined.

  In the present disclosure, the irregular-shaped silica particle A2 refers to a silica particle having a shape in which two or more particles, preferably 2 to 10 particles are aggregated or fused (see FIG. 1). In one or a plurality of embodiments, the silica particle A2 has a shape in which two or more particles having a particle size of 1.5 times or less are aggregated or fused on the basis of the particle size of the smallest silica particle.

  In the present disclosure, odd-shaped and confetti-type silica particles A3 are particles having a shape in which two or more particles are aggregated or fused. In one or a plurality of embodiments, the silica particle A3 is a particle obtained by agglomerating or fusing two or more particles having a particle size of 1.5 times or less, and further having the smallest agglomerated or fused silica particle. In this shape, small particles having a particle size of 1/5 or less are aggregated or fused.

  In one or more embodiments, the non-spherical silica particle A is any one of the silica particles A1, A2, and A3, any two of the silica particles A1, A2, and A3, or the silica particles A1, A2, and Includes all of A3. The ratio (mass ratio) occupied by the total of silica particles A1, A2, and A3 in non-spherical silica particles A is preferably 50% by mass or more from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. Preferably they are 70 mass% or more, More preferably, they are 80 mass% or more, More preferably, they are 90 mass% or more or substantially 100 mass%.

[ΔCV value of non-spherical silica particle A]
In one or a plurality of embodiments, the non-spherical silica particles A preferably have a ΔCV value of more than 0.0%, more preferably from the viewpoint of suppressing a decrease in polishing rate and improving a long-period defect removal rate. It is 0.2% or more, more preferably 0.3% or more, still more preferably 0.4% or more. In one or more embodiments, the non-spherical silica particles A preferably have a ΔCV value of less than 10.0%, more preferably 8.0% or less, and still more preferably 7. 0% or less, still more preferably 4.0% or less. Further, in one or a plurality of embodiments, the non-spherical silica particles A are preferably from 0.0% to less than 10.0%, more preferably from 0.2% to 8.0%, from the same viewpoint. Furthermore, it is preferably 0.3% or more and 7.0% or less, and more preferably 0.4% or more and 4.0% or less.

  In the present disclosure, the ΔCV value of the silica particles is the standard deviation of the particle diameter measured based on the scattering intensity distribution at the detection angle of 30 ° (forward scattering) by the dynamic light scattering method, and the detection angle of 30 ° by the dynamic light scattering. Measured based on the coefficient of variation (CV30) multiplied by 100 divided by the average particle size measured based on the scattering intensity distribution and the scattering intensity distribution at a detection angle of 90 ° (side scattering) by the dynamic light scattering method. The difference (ΔCV) from the value of the coefficient of variation (CV90) multiplied by 100 by dividing the standard deviation of the measured particle diameter by the average particle diameter measured based on the scattering intensity distribution at a detection angle of 90 ° by dynamic light scattering = CV30−CV90), which is a value indicating the angular dependence of the scattering intensity distribution measured by the dynamic light scattering method. The ΔCV value can be specifically measured by the method described in the examples.

  The present inventor, as a method for showing the characteristics of non-spherical silica particles, the average particle size (D1) described above, the average particle size (D1) measured by the dynamic light scattering method and the specific surface area converted particle size by the BET method It was thought that the polishing performance of the silica particles could not be expressed only by the conventional view expressed using the ratio (D1 / D2) to (D2). According to further studies by the present inventors, the ΔCV value is effective as a means for knowing the state of the entire system (bulk) of non-spherical silica particles, and by focusing on these parameters, polishing that has not been known in the past It has been found that the reduction in speed is suppressed, the removal rate of long-period defects is improved, and the range of non-spherical silica that can reduce protrusion defects can be accurately defined. That is, the non-spherical silica particles have different ΔCV values depending on the degree of irregularity, and the ΔCV value can be an index indicating the degree of irregularity of the non-spherical silica particles. For example, when the degree of irregularity of non-spherical silica particles increases, pseudo multiple scattering (self-scattering) is likely to occur, and the angle dependency of the scattering intensity distribution measured by the dynamic light scattering method decreases and the ΔCV value decreases. .

  In this disclosure, “scattering intensity distribution” means three particle size distributions (scattering) of sub-micron or less particles determined by dynamic light scattering (DLS) or quasielastic light scattering (QLS). The particle size distribution of the scattering intensity among the intensity, volume conversion, and number conversion.

[Volume average particle diameter of non-spherical silica particle A by dynamic light scattering method (D1)]
The volume average particle diameter (D1) of the non-spherical silica particles A is preferably 120.0 nm or more and less than 300.0 nm in one or a plurality of embodiments from the viewpoint of suppressing a decrease in polishing rate and improving a long-period defect removal rate. . In one or a plurality of embodiments, the volume average particle diameter (D1) of the non-spherical silica particles A is preferably 120.0 nm or more, more preferably 150.0 nm or more, and further preferably 160.0 nm or more, from the same viewpoint. Even more preferably, it is 170.0 nm or more, still more preferably 180.0 nm or more, still more preferably 190.0 nm or more, and even more preferably 200.0 nm or more. In one or a plurality of embodiments, the volume average particle diameter (D1) of the non-spherical silica particles A is preferably less than 300.0 nm, more preferably less than 260.0 nm, and still more preferably less than 250.0 nm, from the same viewpoint. Even more preferably less than 220.0 nm, even more preferably less than 210.0 nm. Moreover, the volume average particle diameter (D1) of the non-spherical silica particles A is preferably 120.0 nm or more and less than 260.0 nm, more preferably 150.0 nm or more and 260.nm or more, from the same viewpoint in one or more embodiments. Less than 0 nm, more preferably from 160.0 nm to less than 260.0 nm, even more preferably from 170.0 nm to less than 260.0 nm, even more preferably from 180.0 nm to less than 250.0 nm, even more preferably from 190.0 nm to 220 nm It is less than 0.0 nm, and more preferably 200.0 nm or more and less than 210.0 nm.

  In the present disclosure, the volume average particle diameter (D1) of silica particles refers to an average particle diameter based on a scattering intensity distribution measured by a dynamic light scattering method, and unless otherwise specified, the average particle diameter of silica particles is The average particle diameter based on the scattering intensity distribution measured at a detection angle of 90 ° in the dynamic light scattering method. The volume average particle diameter (D1) of the silica particles in the present disclosure can be specifically obtained by the method described in the examples.

[Particle size ratio of non-spherical silica particles A (D1 / D2)]
The ratio (D1 / D2) of the volume average particle diameter (D1) of the non-spherical silica particles A by the dynamic light scattering method and the specific surface area equivalent particle diameter (D2) by the BET method is determined by the polishing rate in one or a plurality of embodiments. From the viewpoint of suppressing the decrease in the length and improving the long-period defect removal rate, it is preferably 2.00 or more, more preferably 2.50 or more, still more preferably 3.00 or more, and even more preferably 3.50 or more. In one or a plurality of embodiments, the particle size ratio (D1 / D2) is preferably 4.00 or less, more preferably 3.90 or less, and further preferably 3.80 or less from the same viewpoint. Moreover, the ratio (D1 / D2) of the volume average particle diameter (D1) of the non-spherical silica particles A by the dynamic light scattering method and the specific surface area converted particle diameter (D2) by the BET method is, in one or more embodiments, From the same viewpoint, it is preferably 2.00 or more and 4.00 or less, more preferably 2.50 or more and 3.90 or less, still more preferably 3.00 or more and 3.90 or less, and even more preferably 3.50 or more and 3. 80 or less.

In the present disclosure, the specific surface area equivalent particle diameter (D2) of the silica particles is given by the formula of D2 = 2720 / S [nm] from the specific surface area Sm ² / g measured by the nitrogen adsorption method (BET method).

  The ratio (D1 / D2) of the volume average particle diameter (D1) measured by the dynamic light scattering method and the specific surface area converted particle diameter (D2) by the BET method may mean the degree of deformation of the silica particles A. In general, the volume average particle diameter (D1) measured by the dynamic light scattering method is to detect the light scattering in the long direction in the case of irregularly shaped particles. Considering this, the larger the degree of deformation, the larger the numerical value, and the specific surface area equivalent particle diameter (D2) by the BET method is expressed in terms of a sphere based on the volume of the obtained particle, and is a smaller numerical value than D1. From the viewpoint of the polishing rate, the ratio (D1 / D2) is preferably large in the above range.

[CV90 of non-spherical silica particle A]
In one or a plurality of embodiments, the CV90 of the non-spherical silica particles A is preferably 20.0% or more, more preferably 25.0% or more, from the viewpoint of suppressing a decrease in polishing rate and improving the long-period defect removal rate. More preferably, it is 27.0% or more, and / or, similarly, 40.0% or less is preferable, more preferably 38.0% or less, still more preferably 35.0% or less, and still more preferably 32. 0.0% or less. In one or a plurality of embodiments, the CV90 of the non-spherical silica particles A is preferably 20.0% or more and 40.0% or less, more preferably 25.0% or more and 38.38. It is 0% or less, more preferably 21.0% or more and 35.0% or less, still more preferably 27.0% or more and 32.0% or less.

  In the present disclosure, CV90 of silica particles is a coefficient of variation obtained by dividing the standard deviation based on the scattering intensity distribution by the average particle diameter and multiplying by 100 in the dynamic light scattering method, and has a detection angle of 90 ° (side scatter). ) Is the CV value measured. Specifically, CV90 of silica particles A can be obtained by the method described in the examples.

[CV30 of non-spherical silica particle A]
The CV30 of the non-spherical silica particles A is a preferable range similar to the range indicated by the CV90. In short, it is appropriately set within a range that maintains the relationship with the ΔCV value (= CV90−CV30).

[Content of non-spherical silica particles A in the polishing composition]
In one or a plurality of embodiments, the content of the non-spherical silica particles A contained in the polishing composition is preferably 0.1% by mass or more from the viewpoint of suppressing a decrease in polishing rate and improving a long-period defect removal rate. 0.5 mass% or more is more preferable, 1 mass% or more is still more preferable, and 2 mass% or more is still more preferable. In addition, the content is preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less, and still more preferably 15% by mass or less from the viewpoint of economy. In one or a plurality of embodiments, the content of the non-spherical silica particles A contained in the polishing composition is 0.1 from the viewpoint of suppressing the decrease in polishing rate, improving the long-period defect removal rate, and economically. The mass is preferably from 30% by mass to 30% by mass, more preferably from 0.5% by mass to 25% by mass, further preferably from 1% by mass to 20% by mass, and still more preferably from 2% by mass to 15% by mass.

[Method for producing non-spherical silica particle A]
Silica particles A are manufactured by the flame melting method, the sol-gel method, and the pulverization method from the viewpoint of suppressing the decrease in the polishing rate in the rough polishing, removing the long-period defects, and reducing the protrusion defects after the rough polishing and the final polishing. The silica particles are preferably produced by the water glass method (particle growth method using an alkali silicate aqueous solution as a starting material). In addition, as a usage form of the non-spherical silica particles A, a slurry form is preferable.

Silica particles are usually 1) a mixture (seed solution) of less than 10% by weight of No. 3 sodium silicate and seed particles (small-size silica) is put in a reaction vessel and heated to 60 ° C. or higher. 2) Spherical particles are grown by dropping an acidic active silicic acid aqueous solution obtained by passing No. 3 silicate through a cation exchange resin and an alkali (alkali metal or quaternary ammonium) to keep the pH constant, and 3) evaporating after aging. It is obtained by concentrating by a method or an ultrafiltration method (Japanese Patent Application Laid-Open No. 47-1964, Japanese Patent Publication No. 1-223412, Japanese Patent Publication No. 4-55125, Japanese Patent Publication No. 4-55127). However, it is often reported that non-spherical silica particles A can be produced if the steps are slightly changed in the same production process. For example, activated silicic acid is very unstable, and when a polyvalent metal ion such as Ca or Mg is intentionally added, an elongated silica sol can be produced. Furthermore, the temperature of the reaction product (evaporates when the boiling point of water is exceeded and the silica is dried at the gas-liquid interface), the pH of the reaction product (silica particles are likely to be linked below 9), and the reaction product SiO ₂ / M ₂ O. (M is an alkali metal or quaternary ammonium), and non-spherical silica can be produced by changing the molar ratio (selectively producing non-spherical silica at 30 to 60) (Japanese Patent Publication No. 8-5657, Patent 2803134, JP-A-2003-133267, JP-A-2006-80406, JP-A-2007-153671, JP-A-2009-137791, JP-A-2009-149493, JP-A-2011-16702). However, the manufacturing method of the silica particle A is limited to these and is not interpreted.

  The method of adjusting the particle size distribution of the non-spherical silica particles A is not particularly limited, but a method of giving a desired particle size distribution by adding particles as new nuclei in the process of particle growth in the production stage. Alternatively, a method of mixing two or more types of silica particles having different particle size distributions to have a desired particle size distribution can be used.

[Spherical silica particles B]
In one or a plurality of embodiments, the polishing liquid composition according to the present disclosure may further contain spherical silica particles B as abrasive grains. In one or more embodiments, examples of the spherical silica particles B include colloidal silica, fumed silica, and surface-modified silica. Colloidal silica is preferable from the viewpoints of suppressing a decrease in polishing rate, improving the long-period defect removal rate, and reducing protrusion defects.

  In the present disclosure, the “spherical silica particle” may be a spherical particle close to a true sphere in one or a plurality of embodiments from the viewpoint of suppressing a decrease in polishing rate and improving a long-period defect removal rate. If it is 0.9-1.1, it can fully be used. The “spherical silica particles” may correspond to generally commercially available colloidal silica in one or more embodiments.

  In one or a plurality of embodiments, the spherical silica particle B may be one type of spherical silica particle or a combination of two or more types of spherical silica particles. When the spherical silica particles B are a combination of two or more types of spherical silica particles, in one or more embodiments, each spherical silica particle meets the requirements for “spherical silica particles B” described in this disclosure. Fulfill. In one or a plurality of embodiments, the spherical silica particles B are preferably two or more types having different particle diameters from the viewpoint of suppressing a decrease in polishing rate and improving a long-period defect removal rate.

[Volume average particle diameter of spherical silica particle B by dynamic light scattering method (D1)]
In one or a plurality of embodiments, the volume average particle diameter (D1) of the spherical silica particles B is preferably 6.0 nm or more and 40.0 nm or less from the viewpoint of suppressing a decrease in polishing rate and improving a long-period defect removal rate. In one or a plurality of embodiments, the volume average particle diameter (D1) of the spherical silica particles B is preferably 6.0 nm or more, and more preferably 7.0 nm or more, from the same viewpoint. In one or a plurality of embodiments, the volume average particle diameter (D1) of the spherical silica particles B is preferably 40.0 nm or less, more preferably 35.0 nm or less, still more preferably 30. 0 nm or less. Further, the volume average particle diameter (D1) of the spherical silica particles B is preferably 6.0 nm or more and 40.0 nm or less, more preferably 6.0 nm or more, from the same viewpoint in one or more embodiments. It is 35.0 nm or less, more preferably 7.0 nm or more and 30.0 nm or less.

[Particle size ratio of spherical silica particles B (D1 / D2)]
The ratio (D1 / D2) of the volume average particle diameter (D1) obtained by the dynamic light scattering method of the spherical silica particles B and the specific surface area converted particle size (D2) obtained by the BET method is the polishing rate in one or more embodiments. From the viewpoint of suppressing the decrease and improving the long-period defect removal rate, it is preferably 1.00 or more, more preferably 1.10 or more, and still more preferably 1.15 or more. In one or a plurality of embodiments, the particle diameter ratio (D1 / D2) of the spherical silica particles B is preferably 1.50 or less, more preferably 1.40 or less, and still more preferably 1.30 or less, from the same viewpoint. It is. Moreover, the ratio (D1 / D2) of the volume average particle diameter (D1) of the spherical silica particles B by the dynamic light scattering method and the specific surface area equivalent particle diameter (D2) by the BET method is the same in one or a plurality of embodiments. From this point of view, it is 1.00 or more and 1.50 or less, preferably 1.10 or more and 1.40 or less, more preferably 1.15 or more and 1.30 or less.

[Content of spherical silica particles B in polishing liquid composition]
In one or more embodiments, the content of the spherical silica particles B contained in the polishing liquid composition is preferably 0.01% by mass or more from the viewpoint of suppressing the reduction in polishing rate and improving the long-period defect removal rate. 0.05 mass% or more is more preferable, 0.1 mass% or more is still more preferable, and 0.2 mass% or more is still more preferable. In addition, the content is preferably 3% by mass or less, more preferably 2.5% by mass or less, still more preferably 2% by mass or less, and even more preferably 1.5% by mass or less from the viewpoint of economy.

[Method for producing spherical silica particle B]
Spherical silica particles B are produced by the flame melting method, the sol-gel method, and the pulverization method from the viewpoint of suppressing the decrease in the polishing rate in the rough polishing, removing the long-period defects, and reducing the protrusion defects after the rough polishing and the final polishing. Rather, silica particles produced by a particle growth method using an alkali silicate aqueous solution as a starting material are preferable. In addition, as a usage form of the spherical silica particles B, a slurry form is preferable.

[Frequency of volume particle size distribution of non-spherical silica particles A and spherical silica particles B]
The total overlap frequency of the volume particle size distributions of the non-spherical silica particles A and the spherical silica particles B in the polishing liquid composition according to the present disclosure is the reduction in the polishing rate and the long-period defect removal rate in one or more embodiments. From the viewpoint of improvement, it is preferably 0% or more and 40% or less, more preferably 10% or more and 38% or less, still more preferably 15% or more and 36% or less, and even more preferably 20% or more and 35% or less. In addition, the overlapping frequency of the volume particle size distribution of the non-spherical silica particles A and the spherical silica particles B can be specifically obtained by the method described in the examples. This is presumed that the above-mentioned effect occurs when the porosity and the small particles present in the voids have an appropriate balance in the silica particle mixture having different sizes.

[Mass ratio of non-spherical silica particles A and spherical silica particles B in the polishing composition]
The mass ratio (A / B) of the content of the non-spherical silica particles A and the spherical silica particles B in the polishing liquid composition according to the present disclosure is such that, in one or a plurality of embodiments, the polishing rate is reduced and long-period defects are suppressed. From the viewpoint of improving the removal rate, it is preferably 80/20 or more, more preferably 85/15 or more, and further preferably 90/10 or more. In one or more embodiments, the mass ratio (A / B) of the content of the non-spherical silica particles A and the spherical silica particles B is preferably 99/1 or less, more preferably 95, in the same viewpoint. / 5 or less, more preferably 96/4 or less. In addition, when the spherical silica particle B is a combination of two or more types of spherical silica particles, the content of the spherical silica particles B refers to the total content thereof. The same applies to the content of non-spherical silica particles A.

[Content of Other Silica Particles in Polishing Liquid Composition]
In one or more embodiments of the polishing liquid composition according to the present disclosure, when the polishing liquid composition contains silica particles in addition to the non-spherical silica particles A and the spherical silica particles B, the entire silica particles in the polishing liquid composition are used. The total mass ratio of the non-spherical silica particles A and the spherical silica particles B is preferably more than 98.0% by mass, more preferably 98.5, from the viewpoint of suppressing a decrease in the polishing rate and improving the long-period defect removal rate. % By mass or more, more preferably 99.0% by mass or more, still more preferably 99.5% by mass or more, still more preferably 99.8% by mass or more, and even more preferably substantially 100% by mass. .

[Nitrogen-containing compounds]
The polishing liquid composition according to the present disclosure contains a nitrogen-containing compound from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. In one or a plurality of embodiments, the nitrogen-containing compound is an aliphatic amine compound or an alicyclic amine compound having a nitrogen content number of 2 to 5 in the molecule from the same viewpoint. In one or a plurality of embodiments, the polishing composition according to the present disclosure contains two or more types of aliphatic amine compounds, or alicyclic amine compounds, or aliphatic amine compounds and alicyclic amine compounds. May be.

  The number of nitrogen atoms in the molecule of the nitrogen-containing compound is 2 to 5 and preferably 2 to 4 from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. In one or a plurality of embodiments, the number of carbon atoms in the molecule of the nitrogen-containing compound is preferably 2 to 8, more preferably from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. There are 4-8. In one or a plurality of embodiments, the nitrogen-containing compound may have a hydroxy group from the viewpoint of workability in consideration of odor and / or boiling point. In addition, in one or a plurality of embodiments, the molecular weight of the nitrogen-containing compound is preferably 60 or more and 500 or less, more preferably 60 or more and 300 or less, more preferably from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. Preferably they are 60 or more and 150 or less, More preferably, they are 60 or more and 135 or less.

  Examples of the aliphatic amine compound include ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, 1,2-diaminopropane, 1,3 from the viewpoint of reducing long-period defects without significantly reducing the polishing rate. -Diaminopropane, 1,4-diaminobutane, hexamethylenediamine, 3- (diethylamino) propylamine, 3- (dibutylamino) propylamine, 3- (methylamino) propylamine, 3- (dimethylamino) propylamine, N-aminoethylethanolamine, N- (2-aminoethyl) diethanolamine, N-aminoethylisopropanolamine, N-aminoethyl-N-methylethanolamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine are preferred, ethylenediamine , , N, N ′, N′-tetramethylethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, 3- (diethylamino) propylamine, 3- (dibutyl Amino) propylamine, 3- (methylamino) propylamine, 3- (dimethylamino) propylamine, N-aminoethylethanolamine, N- (2-aminoethyl) diethanolamine, N-aminoethylisopropanolamine, N-amino Ethyl-N-methylethanolamine, diethylenetriamine, and triethylenetetramine are more preferable, and N-aminoethylethanolamine, diethylenetriamine, and triethylenetetramine are still more preferable.

  From the viewpoint of reducing long-period defects without significantly reducing the polishing rate, the alicyclic amine compound is piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 1-amino-4-methylpiperazine, N- Preferred are methylpiperazine, 1- (2-aminoethyl) piperazine, and hydroxyethylpiperazine, piperazine-1,4-bisethanol, piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, N-methylpiperazine, and hydroxy Ethyl piperazine is more preferred, and piperazine is even more preferred.

  The content of the nitrogen-containing compound in the polishing liquid composition according to the present disclosure is preferably 0.0025% by mass or more, and 0.005% by mass or more from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. Is more preferable, and 0.01 mass% or more is still more preferable. Further, from the same viewpoint, the content of the nitrogen-containing compound in the polishing composition according to the present disclosure is preferably 1.0% by mass or less, more preferably 0.30% by mass or less, and 0.20% by mass or less. More preferably, 0.15 mass% or less is still more preferable, and 0.10 mass% or less is still more preferable. Moreover, 0.0025 mass% or more and 1.0 mass% or less are preferable from the same viewpoint, and content of the nitrogen-containing compound in the polishing liquid composition which concerns on this indication is 0.005 mass% or more and 0.20 mass%. The following is more preferable, 0.01 mass% or more and 0.15 mass% or less is still more preferable, and 0.001 mass% or more and 0.10 mass% or less is still more preferable.

  In the polishing composition according to the present disclosure, the content ratio of silica particles to nitrogen-containing compound [the content of silica particles (% by mass) / the content of nitrogen-containing compound (% by mass)] is one or more. In the embodiment, from the viewpoint of reducing long-period defects without significantly impairing the polishing rate, it is preferably 0.1 or more and 5000 or less, more preferably 1 or more and 4000 or less, further preferably 5 or more and 2400 or less, and even more preferably. Is 40 or more and 1200 or less, and more preferably 60 or more and 600 or less.

[acid]
The polishing composition according to the present disclosure includes an acid selected from the group consisting of phosphoric acids, phosphonic acids, organic phosphonic acids, and combinations thereof from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. contains. The use of the acid in the polishing composition according to the present disclosure includes the use of an acid and / or a salt thereof.

  In the present disclosure, “phosphoric acids” refers to phosphoric acid and other similar compounds having a phosphoric acid skeleton. In one or a plurality of embodiments, pyrophosphoric acid is mentioned as the group of similar compounds. In the present disclosure, unless otherwise specified, “phosphoric acid” includes, in one or more embodiments, inorganic phosphoric acid. In the present disclosure, unless otherwise specified, “phosphonic acid” includes, in one or more embodiments, inorganic phosphonic acid.

  In the present disclosure, “organic phosphonic acid” means, in one or more embodiments, 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), aminotri (methylenephosphonic acid), ethylenediaminetetra ( Methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane- 1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, α-methylphosphonosuccinic acid , And combinations thereof.

  Phosphoric acids, phosphonic acids, organic phosphonic acids, and salts thereof may be used alone or in admixture of two or more.

  As the acid of the polishing composition according to the present disclosure, in one or a plurality of embodiments, phosphoric acid or HEDP is preferable from the viewpoint of reducing long-period defects without significantly impairing the polishing rate.

  When these acid salts are used, there is no particular limitation, and specific examples include metals, ammonium, alkylammonium and the like. Specific examples of the metal include metals belonging to the periodic table (long-period type) 1A, 1B, 2A, 2B, 3A, 3B, 4A, 6A, 7A, or Group 8.

  The content of the acid in the polishing liquid composition according to the present disclosure is preferably 0.001% by mass or more and 5% by mass or less, more preferably, from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. It is 0.01 mass% or more and 4 mass% or less, More preferably, it is 0.05 mass% or more and 3 mass% or less, More preferably, it is 0.1 mass% or more and 2 mass% or less.

  The polishing liquid composition according to the present disclosure may contain an acid different from phosphoric acids, phosphonic acid, and organic phosphonic acid in one or more embodiments as long as the effect thereof is not impaired.

[Oxidant]
The polishing liquid composition according to the present disclosure contains an oxidizing agent from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. Examples of the oxidizing agent include peroxide, permanganic acid or a salt thereof, chromic acid or a salt thereof, peroxo acid or a salt thereof, oxygen acid or a salt thereof from the same viewpoint. Among these, hydrogen peroxide, iron nitrate (III), peracetic acid, ammonium peroxodisulfate, iron sulfate (III), and ammonium iron sulfate (III) are preferable, and metal ions do not adhere to the surface from the viewpoint of improving the polishing rate. From the viewpoint of being used for general purposes and inexpensive, hydrogen peroxide is more preferable. These oxidizing agents may be used alone or in admixture of two or more.

  The content of the oxidizing agent in the polishing composition according to the present disclosure is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% from the viewpoint of improving the polishing rate. From the viewpoint of reducing long-period defects without significantly impairing the polishing rate, it is preferably 4% by mass or less, more preferably 2% by mass or less, and still more preferably 1.5% by mass or less. In addition, from the viewpoint of reducing long-period defects without significantly impairing the polishing rate, the content is preferably 0.01% by mass or more and 4% by mass or less, more preferably 0.05% by mass or more and 2% by mass or less. More preferably, it is 0.1 mass% or more and 1.5 mass% or less.

[Other ingredients]
In the polishing composition according to the present disclosure, other components can be blended as necessary. Examples of other components include thickeners, dispersants, rust inhibitors, basic substances, polishing rate improvers, surfactants, and polymer compounds. The content of these other optional components in the polishing liquid composition according to the present disclosure is preferably blended within a range that does not impair the effects of the present disclosure. % Or less is more preferable.

[water]
The polishing liquid composition according to the present disclosure contains water as a medium. As water, distilled water, ion-exchanged water, pure water, ultrapure water, or the like can be used. The content of water in the polishing liquid composition according to the present disclosure is preferably 61% by mass or more and 99% by mass or less, more preferably 70% by mass or more and 98% by mass or less, because handling of the polishing liquid composition becomes easy. More preferably, it is 80 mass% or more and 97 mass% or less, More preferably, it is 85 mass% or more and 97 mass% or less.

[Alumina abrasive]
The polishing liquid composition according to the present disclosure preferably does not substantially contain alumina abrasive grains from the viewpoint of reducing protrusion defects. In the present disclosure, “substantially free of alumina abrasive grains” means that in one or a plurality of embodiments, it does not contain alumina particles, does not contain alumina particles in an amount that functions as abrasive grains, or polishing results. Not including an amount of alumina particles that affects the amount of alumina particles. The specific content of alumina particles is not particularly limited, but is preferably 5% by mass or less, more preferably 2% by mass or less, still more preferably 1% by mass or less, and substantially 0% as a whole. % Is even more preferred.

[PH]
The pH of the polishing composition according to the present disclosure is pH 1.4 or more and pH 2.5 or less using the above-mentioned acid or a known pH adjuster from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. More preferably, the pH is adjusted to 1.4 to pH 2.3, more preferably pH 1.4 to pH 2.1, still more preferably pH 1.4 to pH 1.9, still more preferably pH 1. It is 5 or more and pH 1.7 or less. In addition, said pH is pH of polishing liquid composition in 25 degreeC, can be measured using a pH meter, and is a numerical value 2 minutes after immersion in the polishing liquid composition of an electrode.

[Method for preparing polishing liquid composition]
The polishing composition according to the present disclosure includes, for example, non-spherical silica particles A, the above-described acid, the above-described oxidizing agent, the above-described nitrogen-containing compound, and water, and, if desired, the spherical silica particles B and other components. Can be prepared by mixing by a known method. In addition, in this indication, "content of the content component in polishing liquid composition" means content of the said component at the time of using polishing liquid composition for grinding | polishing. Therefore, when the polishing liquid composition of the present disclosure is prepared as a concentrate, the content of the components can be increased by the concentration. The mixing is not particularly limited, and can be performed using a homomixer, a homogenizer, an ultrasonic disperser, a stirrer such as a wet ball mill, or the like.

  Accordingly, in another aspect, the present disclosure is a method for producing a polishing liquid composition according to the present disclosure. (1) The ΔCV value is more than 0.0% and less than 10%, and D1 / D2 is 2. Nonspherical silica particles A that are 00 or more and 4.00 or less, and (2) optionally, the sum of the overlapping frequencies of the nonspherical silica particles A and the volume particle size distribution is 0% or more and 40% or less; And spherical silica particles B having a volume average particle diameter (D1) of 6.0 nm or more and 40.0 nm or less by dynamic light scattering method, and (3) aliphatic or alicyclic having a nitrogen content of 2 to 5 in the molecule An amine compound, (4) an acid selected from the group consisting of phosphoric acids, phosphonic acids, organic phosphonic acids, and salts thereof, and combinations thereof; (5) an oxidizing agent; and (6) water. The present invention relates to a manufacturing method including: The content of each component can be as described above. The manufacturing method may include adjusting the pH of the polishing composition so as to be pH 1.4 or higher and pH 2.5 or lower, or a pH in the above range.

[Polished substrate]
As a substrate to be polished roughly using the polishing composition according to the present disclosure, a magnetic disk substrate or a substrate used for a magnetic disk substrate, for example, an Ni-P plated aluminum alloy substrate, silicate glass, or the like is used. And glass substrates such as aluminosilicate glass, crystallized glass, and tempered glass. Especially, as a to-be-polished board | substrate used by this indication, a Ni-P plating aluminum alloy board | substrate is preferable from a viewpoint of intensity | strength and ease of handling. There is no restriction | limiting in particular in the shape of the said to-be-polished substrate, For example, what is necessary is just the shape which has planar parts, such as a disk shape, plate shape, slab shape, prism shape, and the shape which has curved surface parts, such as a lens. Of these, a disk-shaped substrate to be polished is suitable. In the case of a disk-shaped substrate to be polished, the outer diameter is, for example, about 2 to 95 mm, and the thickness is, for example, about 0.5 to 2 mm.

[Method of manufacturing magnetic disk substrate]
Generally, a magnetic disk is obtained by polishing a glass substrate that has undergone a fine grinding process or an aluminum alloy substrate that has undergone a Ni-P plating process through a rough polishing process and a final polishing process, and forming a magnetic disk in a recording part forming process. Manufactured. In one or a plurality of embodiments, the polishing liquid composition according to the present disclosure can be used in a polishing method and / or a manufacturing method of a magnetic disk substrate having the following steps (1) to (3). Accordingly, in one aspect, the present disclosure relates to a method for manufacturing a magnetic disk substrate having the following steps (1) to (3).
(1) Rough polishing step: a step of polishing a polishing target surface of a substrate to be polished using the polishing composition according to the present disclosure;
(2) Cleaning step: a step of cleaning the substrate obtained in step (1), and
(3) Final polishing: The surface to be polished of the substrate obtained in step (2) is polished using a polishing liquid composition containing silica particles C (hereinafter also referred to as “polishing liquid composition for final polishing”). It is a process, Comprising: The said process (1) and (3) is a process performed with another grinding machine.

[Step (1): Rough polishing step]
In one or a plurality of embodiments, the step (1) supplies the polishing composition according to the present disclosure containing the silica particles A and water to the polishing target surface of the substrate to be polished, and contacts the polishing pad with the polishing target surface. And polishing the surface to be polished by moving at least one of the polishing pad and the substrate to be polished. The polishing machine used in the step (1) is not particularly limited, and a known polishing machine for polishing a magnetic disk substrate can be used.

[Method for Supplying Polishing Liquid Composition According to Present Disclosure in Step (1) to Polishing Machine]
As a method of supplying the polishing composition according to the present disclosure to a polishing machine, for example, a method of continuously supplying using a pump or the like can be mentioned. When supplying the polishing liquid composition according to the present disclosure to a polishing machine, in addition to the method of supplying a single liquid containing all components, considering the storage stability of the polishing liquid composition according to the present disclosure, It can also be divided into a plurality of blending component liquids and supplied in two or more liquids. In the latter case, for example, the plurality of compounding component liquids are mixed in the supply pipe or on the substrate to be polished to obtain the polishing liquid composition according to the present disclosure.

[Step (2): Cleaning step]
Step (2) is a step of cleaning the substrate obtained in step (1). Step (2) is a step of cleaning the substrate that has been subjected to the rough polishing in step (1) with a cleaning composition in one or more embodiments. The cleaning method in the step (2) is not particularly limited, but in one or a plurality of embodiments, a method of immersing the substrate obtained in the step (1) in the cleaning composition, and injecting the cleaning composition. And a method of supplying a cleaning composition onto the surface of the substrate obtained in step (1).

[Cleaning composition in step (2)]
As a cleaning composition of a process (2), in one or some embodiment, what contains an alkali agent, water, and various additives as needed can be used.

[Alkaline agent]
The alkaline agent used in the cleaning composition may be either an inorganic alkaline agent or an organic alkaline agent. Examples of the inorganic alkaline agent include ammonia, potassium hydroxide, and sodium hydroxide. Examples of the organic alkali agent include one or more selected from the group consisting of hydroxyalkylamine, tetramethylammonium hydroxide, and choline. These alkaline agents may be used alone or in combination of two or more. From the viewpoint of improving the dispersibility of the residue on the substrate of the cleaning composition and improving the storage stability, the alkaline agent includes potassium hydroxide, sodium hydroxide, monoethanolamine, methyldiethanolamine, and aminoethylethanol. At least one selected from the group consisting of amines is preferred, and at least one selected from the group consisting of potassium hydroxide and sodium hydroxide is more preferred.

[Various additives in cleaning composition]
In addition to alkaline agents, the detergent composition includes nonionic surfactants, chelating agents, ether carboxylates or fatty acids, anionic surfactants, water-soluble polymers, antifoaming agents (surfactants corresponding to ingredients are Except alcohol), preservatives, antioxidants, and the like.

[Step (3): Final polishing step]
In the step (3), the polishing composition for final polishing is supplied to the surface to be polished of the substrate obtained in the step (2), the polishing pad is brought into contact with the surface to be polished, and the polishing pad and / or the substrate to be polished is supplied. In this step, the polishing substrate is moved to polish the surface to be polished. The polishing machine used in step (3) is used in step (1) from the viewpoint of reducing protrusion defects and using pads having different pore diameters from rough polishing in order to efficiently reduce other surface defects. This polishing machine is different from the polishing machine used.

  The method of manufacturing a magnetic disk substrate of this aspect greatly increases the polishing rate of rough polishing by including the rough polishing step of step (1), the cleaning step of step (2), and the final polishing step of step (3). Thus, it is possible to efficiently manufacture a substrate in which long-period defects are reduced without loss, and protrusion defects after finish polishing are reduced.

[Step (3): Polishing liquid composition for finish polishing]
The polishing composition for finish polishing used in the step (3) contains silica particles C as abrasive grains from the viewpoint of reducing protrusion defects after finish polishing. The silica particles C used are preferably colloidal silica from the viewpoint of reducing long wavelength waviness after finish polishing. Moreover, it is preferable that the polishing liquid composition for final polishing does not contain an alumina abrasive grain substantially from a viewpoint of reducing the projection defect after final polishing. The silica particles are spherical in one or more embodiments.

  The average particle diameter (D50) of the silica particles C used in the polishing composition for finish polishing is preferably 5 nm or more and 50 nm or less, more preferably 10 nm or more and 45 nm or less, more preferably from the viewpoint of reducing protrusion defects after finish polishing. Preferably they are 15 nm or more and 40 nm or less, More preferably, they are 20 nm or more and 35 nm or less. Further, the average particle diameter (D50) of the silica particles C is preferably smaller than the average particle diameter (D50) of the non-spherical silica particles A from the viewpoint of reducing protrusion defects after finish polishing. In addition, this average particle diameter can be calculated | required by the method as described in an Example.

  Further, the standard deviation of the particle diameter of the silica particles C is preferably 5 nm or more and 40 nm or less, more preferably 10 nm or more and 35 nm or less, and further preferably 15 nm or more and 30 nm or less, from the viewpoint of reducing protrusion defects after finish polishing. . In addition, this standard deviation can be calculated | required by the method as described in an Example.

  The content of the silica particles C contained in the polishing composition for finish polishing is preferably 0.5% by mass or more and 20% by mass or less from the viewpoint of reducing long wavelength waviness and protrusion defects after finish polishing. The mass% is more preferably 15% by mass or less, still more preferably 3.0% by mass or more and 13% by mass or less, and still more preferably 4.0% by mass or more and 10% by mass or less.

  The polishing composition for finish polishing is one or more selected from a heterocyclic aromatic compound, a polyvalent amine compound, and a polymer having an anionic group from the viewpoint of reducing long-wave waviness and protrusion defects after finish polishing. It is preferable to contain 2 or more types, and it is more preferable to contain a heterocyclic aromatic compound, a polyvalent amine compound, and a polymer having an anionic group.

  The polishing composition for finish polishing preferably contains an acid and an oxidizing agent from the viewpoint of improving the polishing rate. About the preferable usage aspect of an acid and an oxidizing agent, it is the same as that of the case of the polishing liquid composition which concerns on the above-mentioned this indication. Further, the water used for the polishing composition for finish polishing, the pH of the polishing composition for finish polishing and the preparation method thereof are the same as those of the polishing composition according to the present disclosure described above.

  Further, the supply rate of the polishing composition for finish polishing and the method for supplying the polishing composition for finish polishing to the polishing machine in the step (3) are the same as those of the polishing composition according to the present disclosure described above. is there.

  According to the manufacturing method of the present disclosure, in one or a plurality of embodiments, since long-period defects can be reduced without significantly impairing the polishing rate in rough polishing, a magnetic disk substrate with reduced protrusion defects can be obtained with a high substrate yield. Thus, the effect of being able to manufacture with high productivity can be achieved.

[Polishing method]
As another aspect, the present disclosure relates to a polishing method having the above-described step (1), step (2), and step (3). Polished substrate in steps (1) to (3), polishing liquid composition according to the present disclosure, non-spherical silica particles A, polishing liquid composition for final polishing and its silica particles C, polishing method and conditions, cleaning composition The cleaning method can be the same as the method for manufacturing the magnetic disk substrate according to the present disclosure described above.

As another aspect, the present disclosure relates to a method for polishing a magnetic disk substrate that includes the following steps (1) to (3) and is performed by a polishing machine different from the following step (1) and the following step (3). . Polished substrate, polishing pad, polishing liquid composition according to the present disclosure, polishing liquid composition for final polishing and its silica particles, polishing method and conditions, cleaning composition, and cleaning method in steps (1) to (3) The above may be the same as the method for manufacturing a magnetic disk substrate of the present disclosure described above.
(1) The process of grind | polishing the grinding | polishing target surface of a to-be-polished board | substrate (preferably Ni-P plating aluminum alloy board | substrate) using the polishing liquid composition which concerns on this indication.
(2) A step of cleaning the substrate obtained in step (1).
(3) A polishing composition for final polishing containing silica particles C and water is supplied to the surface to be polished of the substrate obtained in step (2), and the polishing pad is brought into contact with the surface to be polished, and the polishing pad And a step of polishing the surface to be polished by moving at least one of the substrates to be polished.

  By using the polishing method of the present disclosure, in one or a plurality of embodiments, it is possible to reduce long-period defects without significantly reducing the polishing rate in rough polishing, so that a magnetic disk substrate with reduced protrusion defects is a high substrate. The effect that it can manufacture with sufficient productivity with a yield can be show | played.

  In one or a plurality of embodiments, a method for manufacturing a magnetic disk substrate and a polishing method according to the present invention include a first method for polishing a substrate to be polished using a polishing liquid composition according to the present disclosure as shown in FIG. A magnetic disk substrate polishing system comprising: a polishing machine; a cleaning unit that cleans the substrate polished by the first polishing machine; and a second polishing machine that polishes the cleaned substrate using the polishing composition B It can be carried out. Therefore, the present invention, in one aspect, a first polishing machine for polishing a substrate to be polished using the polishing composition according to the present disclosure, a cleaning unit for cleaning the substrate polished by the first polishing machine, The present invention relates to a magnetic disk substrate polishing system including a second polishing machine that polishes a substrate after cleaning using a polishing composition for final polishing. The polishing liquid composition and the polishing liquid composition for finish polishing according to the present disclosure are as described above. The substrate to be polished, the polishing pad used in each polishing machine, the polishing method and conditions, the cleaning composition, and the cleaning method Can be the same as the above-described method for manufacturing a magnetic disk substrate according to the present disclosure.

  The present disclosure further relates to one or more of the following embodiments.

<1> A polishing composition for a magnetic disk substrate comprising non-spherical silica particles A, a nitrogen-containing compound, an acid, an oxidizing agent and water,
(1) The non-spherical silica particle A has a shape in which two or more particles are aggregated or fused,
(2) The ΔCV value of the non-spherical silica particles A is more than 0.0% and less than 10%,
Here, the ΔCV value is obtained by dividing the standard deviation based on the scattering intensity distribution at a detection angle of 30 ° by the dynamic light scattering method by the average particle diameter based on the scattering intensity distribution and multiplying by 100 (CV30). The difference (ΔCV = CV30−CV90) from the value obtained by dividing the standard deviation based on the scattering intensity distribution at an angle of 90 ° by the average particle diameter based on the scattering intensity distribution and multiplying by 100 (CV90),
(3) The ratio (D1 / D2) of the volume average particle diameter (D1) by the dynamic light scattering method of the non-spherical silica particles A to the specific surface area equivalent particle size (D2) by the BET method is 2.00 or more and 4.00. And
(4) The nitrogen-containing compound is an aliphatic amine compound or an alicyclic amine compound having a nitrogen content in the molecule of 2 to 5,
(5) the acid is selected from the group consisting of phosphoric acids, phosphonic acids, organic phosphonic acids, and combinations thereof;
(6) A polishing composition for a magnetic disk substrate having a pH of 1.4 to 2.5.

<2> The description of <1>, wherein the non-spherical silica particles A are selected from the group consisting of confetti-type silica particles A1, deformed-type silica particles A2, deformed and confetti-type silica particles A3, and combinations thereof. A polishing composition for a magnetic disk substrate.
<3> The ΔCV value of the non-spherical silica particles A is preferably more than 0.0%, more preferably 0.2% or more, still more preferably 0.3% or more, and even more preferably 0.4% or more. The polishing composition for a magnetic disk substrate according to <1> or <2>.
<4> The non-spherical silica particles A preferably have a ΔCV value of less than 10.0%, more preferably 8.0% or less, still more preferably 7.0% or less, and even more preferably 4.0. % Polishing composition for magnetic disk substrates according to any one of <1> to <3>.
<5> The ΔCV value of the non-spherical silica particles A is preferably more than 0.0% and less than 10.0%, more preferably 0.2% or more and 8.0% or less, and more preferably 0. The polishing composition for a magnetic disk substrate according to any one of <1> to <4>, which is from 0.3% to 7.0%, and even more preferably from 0.4% to 4.0%.
<6> The volume average particle diameter (D1) of the non-spherical silica particles A is preferably 120.0 nm or more, more preferably 150.0 nm or more, still more preferably 160.0 nm or more, and even more preferably 170.0 nm or more. More preferably, the polishing composition for a magnetic disk substrate according to any one of <1> to <5>, which is more preferably 180.0 nm or more, still more preferably 190.0 nm or more, and still more preferably 200.0 nm or more. object.
<7> The volume average particle diameter (D1) of the non-spherical silica particles A is preferably less than 300.0 nm, more preferably less than 260.0 nm, still more preferably less than 250.0 nm, and even more preferably less than 220.0 nm. The polishing composition for a magnetic disk substrate according to any one of <1> to <6>, which is even more preferably less than 210.0 nm.
<8> The volume average particle diameter (D1) of the non-spherical silica particles A is preferably 120.0 nm or more and less than 300.0 nm, more preferably 120.0 nm or more and less than 260.0 nm, and further preferably 150.0 nm or more and 260. Less than 0.0 nm, even more preferably from 160.0 nm to less than 260.0 nm, even more preferably from 170.0 nm to less than 260.0 nm, even more preferably from 180.0 nm to less than 250.0 nm, even more preferably 190.0 nm The polishing composition for a magnetic disk substrate according to any one of <1> to <7>, which is at least 220.0 nm and more preferably at least 200.0 nm and less than 210.0 nm.
<9> The ratio (D1 / D2) of the volume average particle diameter (D1) by the dynamic light scattering method of the non-spherical silica particles A to the specific surface area equivalent particle diameter (D2) by the BET method is preferably 2.00 or more. The polishing composition for a magnetic disk substrate according to any one of <1> to <8>, more preferably 2.50 or more, still more preferably 3.00 or more, and even more preferably 3.50 or more.
<10> The ratio (D1 / D2) of the volume average particle diameter (D1) by the dynamic light scattering method of the non-spherical silica particles A to the specific surface area equivalent particle diameter (D2) by the BET method is preferably 4.00 or less. The polishing composition for a magnetic disk substrate according to any one of <1> to <9>, more preferably 3.90 or less, and still more preferably 3.80 or less.
<11> The ratio (D1 / D2) of the volume average particle diameter (D1) by the dynamic light scattering method of the non-spherical silica particles A to the specific surface area equivalent particle diameter (D2) by the BET method is preferably 2.00 or more. 4.00 or less, more preferably 2.50 or more and 3.90 or less, still more preferably 3.00 or more and 3.90 or less, and even more preferably 3.50 or more and 3.80 or less, <1> to <10 > The polishing composition for a magnetic disk substrate according to any one of the above.
<12> The CV90 of the non-spherical silica particles A is preferably 20.0% or more, more preferably 25.0% or more, and further preferably 27.0% or more, any one of <1> to <11> A polishing composition for a magnetic disk substrate according to claim 1.
<13> The CV90 of the non-spherical silica particles A is preferably 40.0% or less, more preferably 38.0% or less, still more preferably 35.0% or less, and even more preferably 32.0% or less. <1> to <12> The polishing composition for magnetic disk substrates according to any one of <12>.
<14> The CV90 of the non-spherical silica particles A is preferably 20.0% or more and 40.0% or less, more preferably 25.0% or more and 38.0% or less, and further preferably 21.0%. The polishing composition for a magnetic disk substrate according to any one of <1> to <13>, which is 35.0% or less, more preferably 27.0% or more and 32.0% or less.
<15> The content of non-spherical silica particles A contained in the polishing composition is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, still more preferably 1% by mass or more, and even more. The polishing composition for a magnetic disk substrate according to any one of <1> to <14>, which is preferably 2% by mass or more.
<16> The content of non-spherical silica particles A contained in the polishing composition is preferably 30% by mass or less, more preferably 25% by mass or less, still more preferably 20% by mass or less, and even more preferably 15% by mass. % Of the polishing composition for a magnetic disk substrate according to any one of <1> to <15>.
<17> The content of the non-spherical silica particles A contained in the polishing composition is preferably 0.1% by mass to 30% by mass, more preferably 0.5% by mass to 25% by mass, and still more preferably. Is a polishing liquid composition for a magnetic disk substrate according to any one of <1> to <16>, which is 1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 15% by mass or less.
<18> The polishing composition for a magnetic disk substrate according to any one of <1> to <17>, wherein the non-spherical silica particles A are silica particles produced by a particle growth method using water glass as a raw material. .
<19> Furthermore, spherical silica particles B are included, and the spherical silica particles B have a total overlapping frequency of the non-spherical silica particles A and the volume particle size distribution of 0% to 40%, and dynamic light scattering The volume average particle diameter (D1) by the method is 6.0 nm or more and 40.0 nm or less, and the mass ratio (A / B) of the non-spherical silica particles A and the spherical silica particles B in the polishing composition is 80. / 20 or more and 99/1 or less, and the total mass ratio of the non-spherical silica particles A and the spherical silica particles B to the entire silica particles in the polishing composition exceeds 98.0% by mass, from <1><18> The polishing composition for a magnetic disk substrate according to any one of the above.
<20> The polishing liquid for a magnetic disk substrate according to <19>, wherein the spherical silica particles B have a volume average particle diameter (D1) of preferably 6.0 nm or more, and more preferably 7.0 nm or more. Composition.
<21> The volume average particle diameter (D1) of the spherical silica particles B is preferably 40.0 nm or less, more preferably 35.0 nm or less, still more preferably 30.0 nm or less, <19> or <20> 2. A polishing liquid composition for a magnetic disk substrate according to 1.
<22> The volume average particle diameter (D1) of the spherical silica particles B is preferably from 6.0 nm to 40.0 nm, more preferably from 6.0 nm to 35.0 nm, still more preferably from 7.0 nm to 30. The polishing composition for a magnetic disk substrate according to any one of <19> to <21>, which is 0 nm or less.
<23> The ratio (D1 / D2) of the volume average particle diameter (D1) by the dynamic light scattering method of the spherical silica particles B and the specific surface area equivalent particle diameter (D2) by the BET method is preferably 1.00 or more, The polishing composition for a magnetic disk substrate according to any one of <19> to <22>, more preferably 1.10 or more, and still more preferably 1.15 or more.
<24> The ratio (D1 / D2) of the volume average particle diameter (D1) by the dynamic light scattering method of the spherical silica particles B and the specific surface area equivalent particle diameter (D2) by the BET method is preferably 1.50 or less, The polishing composition for a magnetic disk substrate according to any one of <19> to <23>, more preferably 1.40 or less, and still more preferably 1.30 or less.
<25> The ratio (D1 / D2) of the volume average particle diameter (D1) by the dynamic light scattering method of the spherical silica particles B to the specific surface area equivalent particle diameter (D2) by the BET method is preferably 1.00 or more and 1 .50 or less, preferably 1.10 or more and 1.40 or less, more preferably 1.15 or more and 1.30 or less, the polishing composition for a magnetic disk substrate according to any one of <19> to <24> .
<26> The content of the spherical silica particles B contained in the polishing composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more. The polishing composition for a magnetic disk substrate according to any one of <19> to <25>, more preferably 0.2% by mass or more.
<27> The content of the spherical silica particles B contained in the polishing composition is preferably 3% by mass or less, more preferably 2.5% by mass or less, still more preferably 2% by mass or less, and still more preferably 1%. The polishing composition for a magnetic disk substrate according to any one of <19> to <26>, which is 5% by mass or less.
<28> The total overlap frequency of the volume particle size distribution of the non-spherical silica particles A and the spherical silica particles B in the polishing composition is preferably 0% or more and 40% or less, more preferably 10% or more and 38% or less. The polishing composition for a magnetic disk substrate according to any one of <19> to <27>, more preferably 15% to 36%, and still more preferably 20% to 35%.
<29> The mass ratio (A / B) of the content of non-spherical silica particles A and spherical silica particles B in the polishing composition is preferably 80/20 or more, more preferably 85/15 or more, and still more preferably. The polishing composition for a magnetic disk substrate according to any one of <19> to <28>, wherein is 90/10 or more.
<30> The total overlap frequency of the volume particle size distributions of the non-spherical silica particles A and the spherical silica particles B in the polishing composition is preferably 99/1 or less, more preferably 95/5 or less, and still more preferably 96. The polishing composition for a magnetic disk substrate according to any one of <19> to <29>, which is / 4 or less.
<31> The mass ratio of the non-spherical silica particles A to the entire silica particles in the polishing liquid composition or the total mass ratio of the non-spherical silica particles A and the spherical silica particles B is preferably more than 98.0% by mass. More preferably 98.5% by mass or more, still more preferably 99.0% by mass or more, still more preferably 99.5% by mass or more, still more preferably 99.8% by mass or more, and still more preferably substantially The polishing composition for a magnetic disk substrate according to any one of <1> to <30>, which is 100% by mass.
<32> The polishing composition for a magnetic disk substrate according to any one of <1> to <31>, wherein the number of nitrogen atoms in the molecule of the nitrogen-containing compound in the nitrogen-containing compound is preferably 2 to 4. .
<33> The polishing composition for a magnetic disk substrate according to any one of <1> to <32>, wherein the number of carbon atoms in the nitrogen-containing compound is preferably 2 to 8, more preferably 4 to 8. .
<34> The molecular weight of the nitrogen-containing compound is preferably 60 or more and 500 or less, more preferably 60 or more and 300 or less, still more preferably 60 or more and 150 or less, and even more preferably 60 or more and 135 or less, <1> to <33> A polishing liquid composition for a magnetic disk substrate according to any one of 33).
<35> The content of the nitrogen-containing compound in the polishing composition is preferably 0.0025% by mass or more, more preferably 0.005% by mass or more, and still more preferably 0.01% by mass or more. The polishing composition for a magnetic disk substrate according to any one of <1> to <34>.
<36> The content of the nitrogen-containing compound in the polishing composition is preferably 1.0% by mass or less, more preferably 0.30% by mass or less, still more preferably 0.20% by mass or less, and still more preferably. The polishing composition for a magnetic disk substrate according to any one of <1> to <35>, wherein is 0.15% by mass or less, and still more preferably 0.10% by mass or less.
<37> The content of the nitrogen-containing compound in the polishing composition is preferably 0.0025% by mass to 1.0% by mass, more preferably 0.005% by mass to 0.20% by mass, and further The magnetic disk substrate according to any one of <1> to <36>, which is preferably 0.01% by mass or more and 0.15% by mass or less, and more preferably 0.001% by mass or more and 0.10% by mass or less. Polishing liquid composition.
<38> The content ratio of the silica particles and the nitrogen-containing compound [content of silica particles (% by mass) / content of nitrogen-containing compound (% by mass)] in the polishing composition is preferably 0.1. Any one of <1> to <37>, which is 5000 or more, more preferably 1 or more and 4000 or less, further preferably 5 or more and 2400 or less, still more preferably 40 or more and 1200 or less, and even more preferably 60 or more and 600 or less. 2. A polishing liquid composition for a magnetic disk substrate according to 1.
<39> The content of the acid in the polishing composition is preferably 0.001% by mass to 5% by mass, more preferably 0.01% by mass to 4% by mass, and still more preferably 0.05% by mass. The polishing composition for a magnetic disk substrate according to any one of <1> to <38>, wherein the polishing composition is from 1% to 3% by weight, and more preferably from 0.1% to 2% by weight.
<40> The polishing composition for a magnetic disk substrate according to any one of <1> to <39>, wherein the polishing composition contains substantially no alumina particles.
<41> The polishing composition preferably has a pH of 1.4 to 2.5, more preferably 1.4 to 2.3, still more preferably 1.4 to 2.1, and even more preferably. The polishing composition for a magnetic disk substrate according to any one of <1> to <40>, wherein pH is from 1.4 to 1.9, and even more preferably from 1.5 to 1.7.
<42> The polishing composition for a magnetic disk substrate according to any one of <1> to <41>, wherein the polishing target of the polishing composition is a Ni—P plated aluminum alloy substrate.
<43> (1) A step of polishing a surface to be polished of a substrate to be polished using the polishing composition according to any one of <1> to <42>, (2) A substrate obtained in step (1) And (3) polishing the surface of the substrate obtained by the step (2) using a polishing composition containing silica particles, the step (1) and A method of polishing a magnetic disk substrate, wherein (3) is performed by another polishing machine.
<44> (1) A step of polishing a surface to be polished of a substrate to be polished using the polishing composition according to any one of <1> to <42>, (2) A substrate obtained in step (1) And (3) polishing the surface of the substrate obtained by the step (2) using a polishing composition containing silica particles, the step (1) and A method of manufacturing a magnetic disk substrate, wherein (3) is performed by another polishing machine.

  Hereinafter, the present disclosure will be described in more detail by way of examples. However, these examples are illustrative, and the present disclosure is not limited to these examples.

  The polishing liquid composition A according to the present disclosure used in the step (1) and the polishing liquid composition B used in the step (3) are prepared as described below, and the following conditions including the steps (1) to (3) are satisfied. The polishing substrate was polished. The preparation method of the polishing liquid composition, the additive used, the measurement method of each parameter, the polishing conditions (polishing method) and the evaluation method are as follows.

1. Preparation of polishing liquid composition
[Preparation of polishing liquid composition A used in step (1) (rough polishing)]
Polishing liquid composition A used for a process (1) was prepared using the silica abrasive grain (colloidal silica particle) of Table 1, the following additive (amine), the acid of Table 3, hydrogen peroxide, and water (Example) 1-9, Comparative Examples 1-9) (Table 3). The content of each component in the polishing liquid composition A was as follows: colloidal silica particles: 6% by mass, additive: 0.03% by mass, acid: 1.0-2.0% by mass, hydrogen peroxide: 1.0% by mass It was. The pH of the polishing composition according to the present disclosure was 0.9-2.3. In addition, the colloidal silica particle of the silica abrasive grain of Table 1 was manufactured by the water glass method. The pH was measured using a pH meter (manufactured by TOA DK Corporation). The numerical value after 2 minutes of immersing the electrode in the polishing composition was adopted (hereinafter the same).

The types of silica abrasive grains in Table 1 are classifications that can be distinguished by a transmission electron microscope (TEM) observation photograph and analysis using the same in one or a plurality of embodiments.
“Atypical silica particles” refers to non-spherical silica particles having a shape in which two or more particles are aggregated or fused. In one or a plurality of embodiments, the irregular-shaped silica particles refer to particles having a shape in which two or more particles having a particle size of 1.5 times or less are aggregated or fused.
“Konpeira type silica particles” refers to non-spherical silica particles having unique ridges on the surface of the spherical particles. In one or a plurality of embodiments, the confetti type silica particles refer to particles having a shape in which two or more particles different in particle size by 5 times or more are aggregated or fused.
An example of an electron microscope (TEM) observation photograph of an irregular-shaped colloidal silica abrasive grain is shown in FIG. 1, and an example of an electron microscope (TEM) observation photograph of a confetti-type colloidal silica abrasive grain is shown in FIG.
“Spherical silica particles” refers to spherical particles (generally commercially available colloidal silica) that are nearly spherical.
The particle size of the silica particles is a particle size obtained as an equivalent circle diameter measured within one particle in an electron microscope (TEM) observation image, that is, a major axis of an equivalent circle having the same area as the projected area of the particle. .

The organic amine that is the additive used in the polishing composition according to the present disclosure is as follows.
AEEA: N- (β-aminoethyl) ethanolamine (molecular weight 104.5, nitrogen atom number 2, carbon atom number 4): Examples 1, 6, 8, 9 and Comparative Examples 6, 7
HEP: N- (2-hydroxyethyl) piperazine (molecular weight 130.19, 2 nitrogen atoms, 6 carbon atoms): Example 2
DETA: Diethylenetriamine (molecular weight 103.17, nitrogen atom number 3, carbon atom number 4): Example 3
TETA: triethylenetetramine (molecular weight 146.23, number of nitrogen atoms 4, number of carbon atoms 6): Example 4 and Comparative Examples 8 and 9
TEPA: Tetraethylenepentamine (molecular weight 189.3, 5 nitrogen atoms, 8 carbon atoms): Example 5
PEI: Polyethyleneimine (molecular weight 600): Comparative Examples 4 and 5
No added amine: Comparative Examples 1-3

[Preparation of polishing liquid composition B used in step (3) (finish polishing)]
Polishing liquid composition B was prepared using the colloidal silica particle (abrasive grain i) of Table 2, sulfuric acid, hydrogen peroxide, and water. The content of each component in the polishing liquid composition B was colloidal silica particles: 5.0% by mass, sulfuric acid: 0.5% by mass, and hydrogen peroxide: 0.5% by mass. The pH of the polishing composition B was 1.4. This polishing composition B was used in the step (3) in polishing of Examples 1 to 18 and Reference Examples / Comparative Examples 1 to 13.

The abrasive grains i are spherical particles made by the water glass method.

2. Measuring method of each parameter [Volume average particle diameter (D1) and CV90 of abrasive grains a to f measured by dynamic light scattering method]
A standard sample was prepared by adding abrasive grains, sulfuric acid, and hydrogen peroxide to ion-exchanged water and mixing them. The contents of abrasive grains, sulfuric acid, and hydrogen peroxide in the standard sample are 0.1 to 5.0 mass%, 0.2 to 0.4 mass%, and 0.2 to 0.4 mass%, respectively. Adjustments were made as appropriate according to the type of silica abrasive used. The area of the scattering intensity distribution obtained by the Marquardt method at a detection angle of 90 ° when this standard sample is integrated 200 times according to the instructions attached by the manufacturer using the dynamic light scattering device DLS-6500 manufactured by Otsuka Electronics Co., Ltd. Was determined as the volume average particle diameter (D1) of the silica particles. Further, the CV value (CV90) of the silica particles at a detection angle of 90 ° was calculated as a value obtained by dividing the standard deviation in the scattering intensity distribution measured according to the above measurement method by the volume average particle diameter and multiplying by 100.

[ΔCV value]
In the same manner as the CV90 measurement method, the CV value (CV30) of the silica particles at a detection angle of 30 ° was measured, and a value obtained by subtracting CV90 from CV30 was obtained to obtain the ΔCV value of silica particles A or B.
(Measurement conditions for DLS-6500)
Detection angle 90 °
Sampling time: 2-10 (μm) as appropriate Correlation Channel: 256-512 (ch) as appropriate Correlation Method: TI
Sampling temperature: 25.0 ° C
Detection angle 30 °
Sampling time: Adjusted appropriately at 4-20 (μm) Correlation Channel: Adjusted appropriately at 512-2048 (ch) Correlation Method: TI
Sampling temperature: 25 ° C

[Measurement of specific surface area equivalent particle diameter (D2) of abrasive grains a to f by BET method]
The specific surface area of the abrasive grains is subjected to the following [pretreatment], and then approximately 0.1 g of a measurement sample is precisely weighed to 4 digits after the decimal point in a measurement cell, and immediately under the measurement at 110 ° C. for 30 minutes immediately before the measurement of the specific surface area. After drying, the surface area was measured by a nitrogen adsorption method (BET method) using a specific surface area measuring device (micromeritic automatic specific surface area measuring device “Flowsorb III2305” (manufactured by Shimadzu Corporation)).

[D10, D50, and D90 of silica abrasive grains]
Silica abrasive grains were diluted to 1% dispersion with ion-exchanged water, put into the following measuring apparatus, and the average particle diameter was measured.
Measuring equipment: Malvern Zetasizer Nano “Nano S”
Measurement conditions: Sample volume 1.5 mL
: Laser He-Ne, 3.0 mW, 633 nm
: Scattered light detection angle 173 °
The particle sizes at which the cumulative volume frequency of the obtained volume distribution particle size was 10%, 50%, and 90% were defined as D10, D50 (volume average particle size), and D90, respectively.

[Total overlap frequency of volume particle size distribution of silica particles]
Each volume particle size distribution of the silica particle component (abrasive grains a to d) obtained by the same measurement method as D10, D50, and D90 of the silica abrasive grains was obtained. In the combination of abrasive grains used in Examples 7 to 9 (Table 3), the sum of the cumulative volume frequencies of the overlapping particle diameter ranges is the cumulative volume frequency of all silica particle components (200 for the two-component mixed system, 200 for the three-component mixed system). The value obtained by dividing by 300) and multiplying by 100 was calculated as the overlap frequency [%]. An example of a graph in which the volume particle size distribution of the combination of abrasive grains in Example 8 is superimposed is shown in FIG.

[Shape of silica abrasive grains]
A photograph obtained by observing silica abrasive grains with a transmission electron microscope (TEM) manufactured by JEOL (trade name “JEM-2000FX”, 80 kV, 1 to 50,000 times) is captured as image data with a scanner on a personal computer, and analysis software “WinROOF ( Ver. 3.6) ”(distributor: Mitani), the shape of 1000 to 2000 silica particle data was observed.

[Measurement of average secondary particle diameter of abrasive grains]
A 0.5% poise 530 (manufactured by Kao Corporation) aqueous solution is used as a dispersion medium, and the sample is introduced so that the transmittance is 75 to 95%, followed by ultrasonication for 5 minutes. After application, the particle size was measured.
Measuring instrument: Laser diffraction / scattering particle size distribution measuring device LA920 manufactured by Horiba, Ltd.
Circulation strength: 4
Ultrasonic intensity: 4

3. Polishing conditions Polishing of the substrate to be polished was performed according to steps (1) to (3). The conditions for each step are shown below. Step (3) was performed with a polishing machine separate from the polishing machine used in step (1).
[Polished substrate]
The substrate to be polished was an aluminum alloy substrate plated with Ni-P. The substrate to be polished had a thickness of 1.27 mm and a diameter of 95 mm.

[Step (1): Rough polishing]
Polishing machine: Double-side polishing machine (9B-type double-side polishing machine, manufactured by Speed Fam Co.)
Polishing liquid: Polishing liquid composition Polishing pad: Suede type (foam layer: polyurethane elastomer),
Thickness 0.82-1.26mm
Average pore diameter 20-30 μm (Filwel, manufactured by Fujibo)
Plate rotation speed: 35 rpm
Polishing load: 9.8 kPa (set value)
Polishing liquid supply amount: 100 mL / min (0.076 mL / (cm ² · min))
Polishing time: 5 minutes Polishing amount: 0.1 to 1.6 mg / cm ²
Number of substrates loaded: 10

[Step (2): Cleaning]
The substrate obtained in the step (1) was washed under the following conditions.
1. The substrate obtained in the step (1) is immersed for 5 minutes in a tank containing a pH 12 alkaline detergent composition made of 0.1 mass% KOH aqueous solution.
2. The substrate after immersion is rinsed with ion exchange water for 20 seconds.
3. The rinsed substrate is transferred to a scrub cleaning unit in which a cleaning brush is set and cleaned.

[Step (3): Final polishing]
Polishing machine: Double-side polishing machine (9B type double-side polishing machine, manufactured by Speedfam Co., Ltd.), polishing machine separate from the polishing machine used in step (1): Polishing liquid composition B
Polishing pad: Suede type (foam layer: polyurethane elastomer), thickness 0.9mm, average pore diameter 5μm (Fujibo)
Plate rotation speed: 40 rpm
Polishing load: 9.8 kPa
Polishing liquid supply amount: 100 mL / min (0.076 mL / (cm ² · min))
Polishing time: 2 minutes Polishing amount: 0.04 to 0.10 mg / (cm ² · min)
Number of loaded substrates: 10 sheets After the step (3), cleaning was performed. The washing conditions were the same as in the above step (2).

4). Evaluation method [Measurement method and evaluation of polishing rate in step (1)]
Weighing each substrate before and after polishing (measured by Sartorius, “BP-210S”) and measuring the amount of polishing by introducing it into the following formula. The value was calculated. The results are shown in Tables 3-5.
Weight reduction (g) = {weight before polishing (g) −weight after polishing (g)}
Polishing amount (μm) = weight reduction amount (g) / substrate single-sided area (mm ² ) / 2 / Ni—P plating density (g / cm ³ ) × 10 ⁶
(The substrate single-sided area is calculated as 6597 mm ² and Ni-P plating density 8.4 g / cm ³ )

[Method for Evaluating Long-Period Defect (PED) on Substrate Surface After Step (1)]
About both surfaces (20 points in total) of the 10 substrates after the polishing in the step (1), the occurrence rate (%) was determined under the following conditions. As shown in FIG. 4, when a small spot that can be confirmed on the surface of the substrate is PED, and even one point can be visually confirmed on the surface of the substrate, the surface is regarded as having a long-period defect.
Long-period defect rate (%)
= (Number of substrate surfaces on which long-period defects are generated / 20) × 100
The long-period defect occurrence rate was evaluated in five stages according to the following criteria. That is, the larger the value, the lower the occurrence rate of long-period defects. The results are shown in Table 3.
[Evaluation criteria]
Long-period defect occurrence rate: Evaluation: 10% or less: 5 “Generation is extremely suppressed and improvement in substrate yield can be expected”
10% over 20%: 4 “actual production possible”
20% over 30%: 3 “Improvement is required for actual production”
30% over 50%: 2 “Substrate yield is greatly reduced”
50% or more: 1 “far from actual production (same level as when using ordinary silica abrasive grains)”
[measuring equipment]
Optical interference type surface profile measuring machine: OptiFLAT III (manufactured by KLA Tencor)
Radius Inside / Out: 14.87mm / 47.83mm
Center X / Y: 55.44mm / 53.38mm
Low Cutoff: 2.5mm
Inner Mask: 18.50mm, Outer Mask: 45.5mm
Long Period: 2.5mm, Wa Correction: 0.9, Rn Correction: 1.0
No Zernike Terms: 8

[Method for evaluating protrusion defect after step (3)]
Measuring instrument: OSA7100 (manufactured by KLA Tencor)
Evaluation: Polishing was performed using the polishing composition B, and then 4 pieces were selected at random, and each substrate was irradiated with a laser at 10000 rpm to measure the number of abrasive sticks. Divide the total number of abrasive sticks (pieces) on both surfaces of each of the four substrates by 8 to obtain the number of abrasive sticks per board surface (number of protrusion defects) (relative value with Comparative Example 1 as 100). Was calculated. Table 3 shows the relative values of the number of protrusion defects and the results of evaluating the number of protrusion defects based on the following criteria.
[Evaluation criteria]
Number of protrusion defects (relative value): Evaluation Less than 95: A “Generation is extremely suppressed and an improvement in substrate yield can be expected”
95 or more and less than 110: B “actual production possible”
110 to less than 125: C “Improvement is required for actual production”
125 or more: D “Substrate yield decreases significantly”

5. result

As shown in Table 3, in Examples 1-9, compared with Comparative Examples 1-9, the polishing rate of the rough polishing in the step (1) was not greatly impaired, and the substrate after the final polishing in the step (3) The long-period defects (PED) after rough polishing in the step (1) could be reduced without deteriorating the number of protrusion defects.
Moreover, in Examples 7 to 9 using abrasive grains containing non-spherical silica particles and spherical silica particles, in addition to being able to reduce long-period defects (PED) after rough polishing in step (1), Example 1 Compared to ˜6, the polishing rate of the rough polishing in the step (1) was high, and the number of protrusion defects of the substrate after the final polishing in the step (3) was reduced.

  According to the present disclosure, in one or a plurality of embodiments, long-period defects can be reduced while maintaining the polishing rate, so that the substrate yield can be improved while maintaining the productivity of manufacturing the magnetic disk substrate. In one or a plurality of embodiments, the present disclosure can be suitably used for manufacturing a magnetic disk substrate.

Claims (9)

A polishing composition for a magnetic disk substrate comprising non-spherical silica particles A, a nitrogen-containing compound, an acid, an oxidizing agent, and water,
(1) The non-spherical silica particle A has a shape in which two or more particles are aggregated or fused,
(2) The ΔCV value of the non-spherical silica particles A is more than 0.0% and less than 10%,
Here, the ΔCV value is obtained by dividing the standard deviation based on the scattering intensity distribution at a detection angle of 30 ° by the dynamic light scattering method by the average particle diameter based on the scattering intensity distribution and multiplying by 100 (CV30). The difference (ΔCV = CV30−CV90) from the value obtained by dividing the standard deviation based on the scattering intensity distribution at an angle of 90 ° by the average particle diameter based on the scattering intensity distribution and multiplying by 100 (CV90),
(3) The ratio (D1 / D2) of the volume average particle diameter (D1) by the dynamic light scattering method of the non-spherical silica particles A to the specific surface area equivalent particle size (D2) by the BET method is 2.00 or more and 4.00. And
(4) The nitrogen-containing compound is an aliphatic amine compound or an alicyclic amine compound having a nitrogen content in the molecule of 2 to 5,
(5) the acid is selected from the group consisting of phosphoric acids, phosphonic acids, organic phosphonic acids, and combinations thereof;
(6) A polishing composition for a magnetic disk substrate having a pH of 1.4 or more and 2.5 or less.   The polishing liquid composition for a magnetic disk substrate according to claim 1, wherein the nitrogen-containing compound has 2 to 8 carbon atoms. Further, spherical silica particles B are included,
The spherical silica particles B have a total overlap frequency of 0% or more and 40% or less of the non-spherical silica particles A and a volume particle size distribution, and a volume average particle diameter (D1) by a dynamic light scattering method of 6. 0 nm or more and 40.0 nm or less,
The mass ratio (A / B) of the non-spherical silica particles A and the spherical silica particles B in the polishing liquid composition is 80/20 or more and 99/1 or less, and is based on the entire silica particles in the polishing liquid composition. 3. The polishing composition for a magnetic disk substrate according to claim 1, wherein the total mass ratio of the non-spherical silica particles A and the spherical silica particles B exceeds 98.0 mass%.   The polishing composition for a magnetic disk substrate according to claim 1, wherein the polishing composition contains substantially no alumina particles.   5. The polishing composition for a magnetic disk substrate according to claim 1, wherein CV90 of the non-spherical silica particles A is 20.0% or more and 40.0% or less.   The polishing composition for a magnetic disk substrate according to claim 1, wherein the non-spherical silica particles A are silica particles produced by a water glass method.   The polishing composition for a magnetic disk substrate according to any one of claims 1 to 6, wherein a polishing target of the polishing composition is a Ni-P plated aluminum alloy substrate. (1) A step of polishing a polishing target surface of a substrate to be polished using the polishing composition according to any one of claims 1 to 7,
(2) a step of cleaning the substrate obtained in step (1), and
(3) The substrate obtained in step (2) has a step of polishing the surface to be polished using a polishing liquid composition containing silica particles,
A method for polishing a magnetic disk substrate, wherein the steps (1) and (3) are carried out by another polishing machine. (1) A step of polishing a polishing target surface of a substrate to be polished using the polishing composition according to any one of claims 1 to 7,
(2) a step of cleaning the substrate obtained in step (1), and
(3) The substrate obtained in step (2) has a step of polishing the surface to be polished using a polishing liquid composition containing silica particles,
A method of manufacturing a magnetic disk substrate, wherein the steps (1) and (3) are performed by another polishing machine.