JP6495095B2 - Polishing liquid composition for magnetic disk substrate - Google Patents

Description

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

  In general, when silica particles are used, it is known that the polishing rate is lower than that of alumina particles. So far, studies have been made on improving the polishing rate using silica particles (for example, Patent Document 1).

  Furthermore, 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 silica particles as abrasive grains in the rough polishing step has been proposed. (Patent Documents 2 and 3).

  On the other hand, there is PED (polish-enhanced defects) as a surface defect of a magnetic disk substrate using a Ni-P plated aluminum alloy substrate (Patent Document 4). PED is also called “long-period defect” of a magnetic disk substrate together with a grind scratch.

  Further, by adding an amine compound as an additive of the polishing composition, polishing suppression for the insulating film (Patent Document 5), polishing speed improvement of the sapphire substrate (Patent Document 6), residual particle reduction (Patent Document 7), Attempts have also been made to suppress polishing of tantalum substrates (Patent Document 8).

JP 2009-91197 A JP 2014-29754 A JP 2014-29755 A JP 2003-41377 A JP 2001-89747 A JP 2009-297818 A JP 2012-12469 A JP 2002-519475 A

  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 step is performed as silica particle abrasive grains instead of alumina particles, a problem that long-period defects cannot be removed newly occurs. In the case of performing a rough polishing process using alumina particles as abrasive grains, in general, the problem of long-period defects 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.

  In Patent Documents 2 and 3, if rough polishing is performed using non-spherical silica particles defined by predetermined parameters as abrasive grains, even if the polishing composition is substantially free of alumina particles, Disclosed is that long-wave waviness after rough polishing can be reduced without significantly extending the polishing time. However, for long-period defects, further improvement in removal rate is desired.

  Therefore, in one aspect, the present disclosure provides a magnetic disk substrate capable of reducing long-period defects on a substrate surface after rough polishing without greatly impairing the polishing rate in rough polishing using non-spherical silica particles as abrasive grains. A polishing liquid composition is provided.

  In one aspect, the present disclosure includes non-spherical silica particles, a nitrogen-containing compound, and water, and the non-spherical silica particles have a shape in which two or more particles are aggregated or fused, and the nitrogen-containing compound is The present invention relates to a polishing liquid composition for a magnetic disk substrate, which is an organic amine compound having 2 or 3 N atoms in the molecule.

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 concerning 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 target 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 method for manufacturing a magnetic disk substrate, which is performed by another polishing machine.

  In another aspect, the present disclosure provides 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, and silica. 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 containing particles.

  According to the present disclosure, since alumina particles are not used, protrusion defects after rough polishing and after final polishing can be greatly reduced. Furthermore, according to the present disclosure, in one or a plurality of embodiments, it is possible to achieve 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.

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 diagram illustrating an embodiment of a polishing system. 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.

  In the rough polishing process using the polishing liquid composition containing predetermined non-spherical silica particles as abrasive grains, the present disclosure provides the polishing liquid composition with nitrogen having 2 or 3 nitrogen (N) atoms in the molecule. It is based on the knowledge that when the containing compound is added, 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.

The details of the mechanism by which the removal rate of long-period defects is improved by combining a given non-spherical silica particle with a nitrogen-containing compound having 2 or 3 nitrogen atoms in the molecule are not clear, but are assumed as follows. The That is, the predetermined nitrogen-containing compound is bonded to both the silica particles and the substrate (Ni-P plated aluminum alloy substrate), and improves the adsorption property 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. On the other hand, when the number of nitrogen atoms in the molecule of the nitrogen-containing compound is 4 or more, the silica particles are aggregated and / or the adsorption of the nitrogen-containing compound to the substrate surface is promoted, and the substrate surface is excessively protected, As a result, it is considered that the polishing rate is reduced. Therefore, the improved adsorption rate and the removal rate of long-period defects are brought about by the balanced adsorption of the nitrogen-containing compound having 2 or 3 nitrogen atoms in the molecule and the adsorption to the substrate surface. Conceivable. Furthermore, by increasing the compressibility of the polishing pad, it becomes easier for the polishing pad to follow the substrate, so that the frequency of contact of the silica particles with the substrate increases, and the removal rate of long-period defects is further improved. It is done.
However, the present disclosure need not be construed as being limited to these mechanisms.

  That is, in one aspect, the present disclosure includes non-spherical silica particles, a nitrogen-containing compound, and water, and the non-spherical silica particles have a shape in which two or more particles are aggregated or fused. Further, the present invention relates to a magnetic disk substrate polishing liquid composition (hereinafter, also referred to as “polishing liquid composition according to the present disclosure”), which is an organic amine compound having 2 or 3 N atoms in the molecule.

  In the present disclosure, the “long-period defect” includes a grind flaw and a PED (polish enhanced defect) generated in the manufacturing process of the Ni—P plated aluminum alloy substrate. Grind scratches refer to grinding marks on a grindstone in a process of grinding an aluminum alloy substrate before plating (grinding process). PED refers to a portion of insufficient annealing due to water or foreign matter adhering to the substrate surface in the annealing step in the plating film forming step on the 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]
The polishing liquid composition according to the present disclosure contains non-spherical silica particles. 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 impairing the polishing rate, the non-spherical silica particles are preferably colloidal silica, and more preferably colloidal silica having the following specific shape. 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 impairing the polishing rate, but the silica particles produced by the water glass method It is preferable that

[Shape of non-spherical silica particles]
The shape of the non-spherical silica particles is a shape in which a plurality of 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 are at least selected from the group consisting of confetti-type silica particles A1, deformed-type silica particles A2, and deformed and confetti-type silica particles A3. One type of silica particles is preferable, and at least one type of silica particles selected from the group consisting of confetti-type silica particles A1 and irregular-shaped silica particles A2 is more preferable, and irregular-shaped silica particles A2 Is more preferable.

  In the present disclosure, the confetti-type silica particle A1 refers to a silica particle having a unique ridge-like protrusion on a spherical particle surface in one or a plurality of embodiments. 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. The silica particles A1 are preferably in a state where particles having a small particle size are partially embedded in particles having a large particle size. 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. 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 particles are any one of silica particles A1, A2, and A3, any two of silica particles A1, A2, and A3, or silica particles A1, A2, and A3. Including all of. The total content of the silica particles A1, A2 and A3 in the non-spherical silica particles is preferably 50% by mass or more, more preferably 70% by mass, from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. As mentioned above, More preferably, it is 80 mass% or more, More preferably, it is 90 mass% or more. Furthermore, from the same viewpoint, the total content of the silica particles A1 and the silica particles A2 is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 100% by mass in the non-spherical silica particles. is there.

  When the non-spherical silica particles include silica particles A1 and A2, the mass ratio A1 / A2 between the silica particles A1 and the silica particles A2 is preferably in the range of 5/95 or more and 95/5 or less in one or more embodiments. It is. From the viewpoint of reducing long-period defects without significantly impairing the polishing rate, the mass ratio A1 / A2 is more preferably 20/80 or more and 80/20 or less, and further preferably 20/80 or more and 60/40 or less. More preferably 20/80 to 40/60, and still more preferably 20/80 to 30/70.

[Average particle diameter of non-spherical silica particles (D50)]
The average particle diameter (D50) of the non-spherical silica particles is a volume average particle diameter (D50) measured by a laser light scattering method. The average particle diameter (D50) of the non-spherical silica particles is preferably 50 nm or more, more preferably 60 nm or more, still more preferably 100 nm or more, and still more preferably, from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. Is 110 nm or more. From the same viewpoint, the average particle size (D50) of the non-spherical silica particles is preferably 500 nm or less, more preferably 400 nm or less, still more preferably 300 nm or less, still more preferably 200 nm or less, and even more preferably 170 nm or less. It is. More specifically, the average particle diameter (D50) of the non-spherical silica particles is preferably from 50 nm to 500 nm, more preferably from 60 nm to 400 nm, still more preferably from 100 nm to 300 nm, from the same viewpoint. More preferably, it is 110 nm or more and 200 nm or less, and still more preferably 110 nm or more and 170 nm or less.

[Absolute maximum length of non-spherical silica particles]
In the present disclosure, the absolute maximum length of a particle refers to the length of the maximum value of the distance between any two points on the particle outline. The absolute maximum length of the non-spherical silica particles can be obtained by observation with an electron microscope. The average value of the absolute maximum length of the non-spherical silica particles (hereinafter, also referred to as “average absolute maximum length”) is preferably 80 nm or more from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. More preferably, it is 90 nm or more, still more preferably 100 nm or more, still more preferably 110 nm or more, and still more preferably 120 nm or more. From the same viewpoint, the average absolute maximum length of the non-spherical silica particles is preferably 500 nm or less, more preferably 400 nm or less, and still more preferably 350 nm or less. More specifically, the average absolute maximum length of the non-spherical silica particles is preferably from 80 nm to 500 nm, more preferably from 90 nm to 400 nm, still more preferably from 90 nm to 350 nm, from the same viewpoint.

[Area ratio of non-spherical silica particles (b / a × 100)]
In the present disclosure, the area ratio (b / a × 100) is obtained by dividing the area b of a circle whose diameter is the absolute maximum length of the particle by the projected area a of the particle obtained by electron microscope observation and multiplying by 100. Value (%).

The non-spherical silica particles have an area ratio (b / a × 100) of individual silica particles constituting the non-spherical silica particles of 110% or more and 200% from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. The following non-spherical silica particles contain 30% by mass or more of silica particles, preferably 30% by mass to 100% by mass, more preferably 50% by mass to 100% by mass, and still more preferably 70% by mass. % To 100% by mass, still more preferably 80% to 100% by mass, and still more preferably 90% to 100% by mass. The mass of each silica particle is calculated by converting the projected area a of the particle obtained by electron microscope observation into a sphere with a spherical cross-sectional area and calculating the volume, and further calculating the density of the silica particle as 2.2 g / cm ^3. can get.

  The average value of the area ratio (b / a × 100) of the non-spherical silica particles is preferably 110% or more from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. The average value of the area ratio of non-spherical silica particles (b / a × 100) is preferably 110% or more and 200% or less, more preferably from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. It is 120% or more and 190% or less, more preferably 130% or more and 185% or less, and still more preferably 140% or more and 180% or less.

[BET specific surface area of non-spherical silica particles]
BET specific surface area of the non-spherical silica particles, from the viewpoint of reducing the long-period defect without impairing the polishing rate significantly, preferably not more than 10 m ² / g or more 200 meters ² / g, more preferably 20 m ² / g or more 100 m ² / G or less, more preferably 30 m ² / g or more and 80 m ² / g or less.

[Content of non-spherical silica particles]
The content of the non-spherical silica particles contained in the polishing liquid composition according to the present disclosure is preferably 0.1% by mass or more, and 0.5% by mass from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. % Or more is more preferable, 1 mass% or more is still more preferable, and 2 mass% or more is still more preferable. 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. Therefore, the content of the non-spherical silica particles in the polishing liquid composition is from 0.1% by mass to 30% by mass from the viewpoint of reducing long-period defects without significantly impairing the polishing rate and from the viewpoint of economy. The following is preferable, 0.5 mass% or more and 25 mass% or less are more preferable, 1 mass% or more and 20 mass% or less are still more preferable, and 2 mass% or more and 15 mass% or less are still more preferable.

  In one or a plurality of embodiments, the polishing liquid composition according to the present disclosure may contain other silica particles such as spherical silica in addition to the non-spherical silica particles. In one or a plurality of embodiments, the content of other silica particles is in a range that does not significantly impair the reduction of the projection defects after polishing and / or the reduction of the polishing rate and / or the long-period defects. As other silica particles, in one or a plurality of embodiments, spherical silica particles are preferable from the viewpoint of improving the polishing rate and reducing long-period defects. When the polishing liquid composition according to the present disclosure contains spherical silica particles, the mass ratio of the spherical silica particles to the non-spherical silica particles (spherical silica / non-spherical silica) is more than 0 and not more than 30/70 and more than 0. 25/75 or less, or more than 0 and 20/80 or less.

[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 organic amine compound having 2 or 3 N atoms in the molecule from the same viewpoint. In one or a plurality of embodiments, the organic amine compound includes at least one selected from the group consisting of an aliphatic amine compound and an alicyclic amine compound from the same viewpoint. Thus, in one or more embodiments, the nitrogen-containing compound is selected from an aliphatic amine compound having 2 or 3 N atoms in the molecule and an alicyclic amine compound having 2 or 3 N atoms in the molecule. There may be mentioned at least one compound. In one or a plurality of embodiments, the polishing liquid composition according to the present disclosure includes two or more types of aliphatic amine compounds, two or more types of alicyclic amine compounds, or two or more types of aliphatic amine compounds, and An alicyclic amine compound may be contained. In the present disclosure, the nitrogen-containing compound is one or more compounds having any amino group from primary to tertiary from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. Preferably there is.

  The number of nitrogen atoms in the molecule of the nitrogen-containing compound is 2 or 3 and preferably 2 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 may have a hydroxy group from the viewpoint of workability in consideration of odor and / or boiling point. 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, and still more preferably, from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. 60 or more and 150 or less, still more preferably 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, At least one selected from the group consisting of N-aminoethylethanolamine, N- (2-aminoethyl) diethanolamine, N-aminoethylisopropanolamine, N-aminoethyl-N-methylethanolamine, and diethylenetriamine is preferred, Ethylenediamine, N, N N ′, N′-tetramethylethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, 3- (diethylamino) propylamine, 3- (dibutylamino) propyl Amines, 3- (methylamino) propylamine, 3- (dimethylamino) propylamine, N-aminoethylethanolamine, N- (2-aminoethyl) diethanolamine, N-aminoethylisopropanolamine, and N-aminoethyl- At least one selected from the group consisting of N-methylethanolamine is more preferable, and N-aminoethylethanolamine is 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- At least one selected from the group consisting of methylpiperazine, 1- (2-aminoethyl) piperazine, hydroxyethylpiperazine, and piperazine-1,4-bisethanol is preferred, and piperazine, 2-methylpiperazine, 2, 5- At least one selected from the group consisting of dimethylpiperazine, N-methylpiperazine, and hydroxyethylpiperazine is more preferable, and piperazine is more preferable.

  In the polishing composition according to the present disclosure, the content of the nitrogen-containing compound is preferably 0.0025% by mass or more, and 0.0050% by mass or more from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. Is more preferable, and 0.010 mass% or more is still more preferable. And 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. More specifically, the content of the nitrogen-containing compound in the polishing composition according to the present disclosure is preferably 0.0025% by mass or more and 1.0% by mass or less, and 0.0025% by mass or more and 0% by mass from the same viewpoint. 20 mass% or less is more preferable, 0.0050 mass% or more and 0.15 mass% or less is still more preferable, and 0.0050 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 the non-spherical silica particles to the nitrogen-containing compound [content of non-spherical silica particles (mass%) / content of nitrogen-containing compound (mass%)] is one. Alternatively, in a plurality of embodiments, 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, still more preferably 5 or more and 2400 or less, and further More preferably, they are 40 or more and 1200 or less, More preferably, they are 60 or more and 600 or less.

[acid]
The polishing composition according to the present disclosure preferably contains an acid from the viewpoint of improving the polishing rate. The use of the acid in the polishing composition according to the present disclosure includes at least one use selected from the group consisting of an acid and a salt thereof. Examples of acids used include nitric acid, sulfuric acid, sulfurous acid, persulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, phosphonic acid, phosphinic acid, pyrophosphoric acid, tripolyphosphoric acid, amidosulfuric acid, 2-aminoethylphosphonic acid, and the like. 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1 , 2-triphosphonic acid, ethane-1-hydroxy-1,1,2-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-methylphosphonocoha Organic phosphonic acids such as acids, aminophosphonic acids such as hydroxyphosphonoacetic acid, phytic acid, glutamic acid, picolinic acid, aspartic acid, citric acid, tartaric acid, oxalic acid, nitroacetic acid, maleic acid, catechol disulfonic acid, oxaloacetic acid, etc. A carboxylic acid etc. are mentioned. Among these, phosphoric acid, sulfuric acid, citric acid, tartaric acid, maleic acid, catechol disulfonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (from the viewpoint of reducing long-period defects without significantly impairing the polishing rate At least one selected from the group consisting of methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) and salts thereof, more preferably sulfuric acid, 1-hydroxyethylidene-1,1-diphosphone At least one selected from the group consisting of acids, aminotri (methylenephosphonic acid) and salts thereof is more preferred, and sulfuric acid is even more preferred.

  The above acids and salts thereof may be used alone or in admixture of two or more, but from the viewpoint of reducing long-period defects without significantly impairing the polishing rate, a mixture of two or more may be used. Preferably, two or more acids selected from the group consisting of phosphoric acid, sulfuric acid, citric acid, tartaric acid and 1-hydroxyethylidene-1,1-diphosphonic acid, catechol disulfonic acid, and aminotri (methylenephosphonic acid) are mixed. And more preferably used.

  There is no limitation in particular as said acid salt, Specifically, the salt of said acid and at least 1 sort (s) selected from the group which consists of a metal, ammonium, and alkylammonium is mentioned. Specific examples of the metal include metals belonging to 1A, 1B, 2A, 2B, 3A, 3B, 4A, 6A, 7A, or Group 8 of the periodic table (long period type). Among these, as the acid salt, a salt of the above acid with a metal belonging to Group 1A or ammonium is preferable from the viewpoint of improving the polishing rate and roll-off characteristics.

  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.

[Oxidant]
The polishing composition according to the present disclosure preferably 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, the oxidizing agent is preferably at least one selected from the group consisting of hydrogen peroxide, iron nitrate (III), peracetic acid, ammonium peroxodisulfate, iron sulfate (III), and ammonium iron sulfate (III). Hydrogen peroxide is more preferable from the viewpoint of improving the polishing rate and from the viewpoint that metal ions do not adhere to the surface and are generally used and inexpensive. 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. is there. More specifically, from the viewpoint of reducing long-period defects without significantly reducing 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. It is 2 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. Specific examples of other components include, but are not limited to, polyoxyethylene lauryl ether, polyethylene glycol, and sodium lauryl sulfate. The other optional components are preferably blended in the polishing composition according to the present disclosure as long as the effects of the present disclosure are not impaired. The content of other optional components in the polishing composition according to the present disclosure is preferably 10% by mass or less, and more preferably 5% by mass or less.

[water]
The polishing liquid composition according to the present disclosure contains water as a medium. As the water, at least one selected from the group consisting of distilled water, ion-exchanged water, pure water, and ultrapure water 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 in the polishing composition is not particularly limited, but is preferably 5% by mass or less, more preferably 2% by mass or less, and more preferably 1% by mass or less as a whole abrasive grain. Even more preferably, it is substantially 0%.

[PH]
The pH of the polishing composition according to the present disclosure is pH 0.5 or more and pH 6.0 or less using the above-described acid or a known pH adjuster from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. It is preferably adjusted to pH 0.7 or more, pH 4.0 or less, more preferably pH 0.9 or more and pH 3.0 or less, still more preferably pH 1.0 or more and pH 3.0 or less, still more preferably pH 1. It is 0 or more and pH 2.0 or less. The above pH is the pH of the polishing composition at 25 ° C., which can be measured using a pH meter, and is a value two minutes after immersion of the electrode in the polishing composition.

[Method for preparing polishing liquid composition]
The polishing composition according to the present disclosure includes, for example, non-spherical silica particles, a nitrogen-containing compound (organic amine compound), and water, and, if desired, one or more selected from acids, oxidizing agents, and other components. It can be prepared by mixing by a known method. In the present disclosure, the “content of the component in the polishing liquid composition” refers to the content of the component at the time when the polishing liquid composition is used for 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.

[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 substrate used by this indication, a Ni-P plating aluminum alloy substrate is preferred. 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 magnetic disk substrate polishing method and / or manufacturing method 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 step: a step of polishing the surface to be polished of the substrate obtained in step (2) using a polishing liquid composition containing silica particles (hereinafter also referred to as “polishing liquid composition B”). In addition, the steps (1) and (3) are steps performed by different polishing machines.

[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 non-spherical silica particles, a nitrogen-containing compound, and water to the surface to be polished of the substrate to be polished, and the polishing target A polishing pad is brought into contact with the surface, and at least one of the polishing pad and the substrate to be polished is moved to polish the surface 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.

[Polishing pad A in step (1)]
As a polishing pad (hereinafter, also referred to as “polishing pad A”) used in step (1) of the production method according to the present disclosure, a base is used from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. A suede type polishing pad having a layer and a foamed surface layer, and the surface layer has a compressibility of 2.5% or more. In the present disclosure, the surface layer of the polishing pad A is preferably made of polyurethane from the same viewpoint. In the present disclosure, the surface member (surface layer) of the polishing pad A preferably includes a polyurethane elastomer from the same viewpoint.

<Structure of polishing pad A>
As the foam layer that is the surface layer of the polishing pad A, in one or a plurality of embodiments, a closed foam type and a continuous foam type can be used, but a continuous foam type is preferable from the viewpoint of discharge of polishing waste. used. Examples of the continuous foaming type polishing pad include, for example, “CMP Technology Basic Example Course Series 2nd Mechanochemical Polishing (CMP) Basics and Examples (Polishing Pad Edition) May 27, 1998 Material Global Net Corporation Edition”, Alternatively, a polishing pad as described in “CMP Science, Masahiro Kashiwa, Science Forum, Chapter 4” can be used. Here, the suede type has, in one or a plurality of embodiments, a base layer and a foam layer having spindle-shaped pores perpendicular to the base layer as described in JP-A-11-33579. Refers to the structure.

  In one or a plurality of embodiments, the suede type polishing pad is manufactured by the following method. A solution in which polyurethane elastomer is dissolved in a solvent such as dimethylformamide (DMF) is applied on a base layer made of polyethylene terephthalate (PET), and then immersed in water or a mixed solution of water and a solvent for polyurethane elastomer solution. Then, wet coagulation is carried out, followed by washing with water for solvent removal and drying. As a result, a foam layer having spindle-shaped pores perpendicular to the base layer is formed on the base layer. And by polishing the surface of the obtained foam layer with sandpaper or the like, a suede type polishing pad having a foam layer having a pore portion on the surface and a spindle-shaped pore perpendicular to the base layer Is obtained.

<Material of polishing pad A>
Examples of the material of the base layer of the polishing pad A include, in one or a plurality of embodiments, a non-woven fabric made of natural fibers such as cotton or a synthetic fiber, a base layer obtained by filling a rubber-like substance such as styrene butadiene rubber, and the like. However, a polyethylene terephthalate (PET) film or a polyester film is preferable, and a PET film is more preferable from the viewpoint of reducing microwaviness and obtaining a resin film with high hardness. Examples of the material of the foam layer (surface layer) of the polishing pad A include polyurethane elastomer, polystyrene, polyester, polyvinyl chloride, natural rubber, and synthetic rubber in one or a plurality of embodiments. From the viewpoint of reducing long-period defects without loss, polyurethane elastomers are preferred.

<Compression rate of polishing pad A>
The compression rate of the foam layer (surface layer) of the polishing pad A is 2.5% or more, preferably 20.0% or less, from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. Preferably it is 15.0% or less, More preferably, it is 10.0% or less, More preferably, it is 7.0% or less, More preferably, it is 5.0% or less.

The compressibility of the polishing pad can be measured by a compression tester based on the compressibility measurement method described in Japanese Industrial Standard (JIS) L1096. That is, the value obtained by subtracting the thickness (T1) of the polishing pad measured under 1000 g / cm ² from the thickness (T0) of the polishing pad measured under standard pressure (100 g / cm ² ) is divided by T0. It can be determined by multiplying the value by 100. The compressibility of the polishing pad can be controlled by, for example, the thickness of the foam layer, the pore size on the base layer side of the foam layer, or the material of the base layer.

<Average pore diameter of polishing pad A>
The average pore diameter of the pores on the surface of the polishing pad A is preferably 10 μm or more and 100 μm or less, more preferably 15 μm or more and 80 μm or less, and still more preferably 20 μm, from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. It is 60 μm or less, and more preferably 25 μm or more and 55 μm or less.

  The average pore size of the pores on the surface of the polishing pad is the addition of a pigment such as carbon black, a hydrophilic activator that promotes foaming, or a hydrophobic activator that stabilizes wet coagulation of the polyurethane elastomer. It can be controlled by adding an agent. The average pore diameter can be determined by the following method. First, the surface of the polishing pad is observed with a scanning electron microscope (preferably 100 to 300 times), and an image is taken into a personal computer (PC). Then, the captured image is analyzed by image analysis software on a PC, and the average pore diameter can be obtained as the average diameter of the equivalent circle diameter of the pores. For example, WinROOF (Mitani Corporation) can be used as the image analysis software.

<Thickness of polishing pad A>
The thickness of the polishing pad A is preferably from 0.7 mm to 1.5 mm, more preferably from 0.8 mm to 1.4 mm, and still more preferably from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. It is 0.8 mm or more and 1.3 mm or less, and more preferably 0.9 mm or more and 1.3 mm or less.

[Step (1): Polishing load]
In the present disclosure, the polishing load means the pressure of the surface plate applied to the polishing surface of the substrate to be polished during polishing. The polishing load in the step (1) is preferably 30 kPa or less, more preferably 25 kPa or less, still more preferably 20 kPa or less, still more preferably 18 kPa or less, from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. Even more preferably, it is 16 kPa or less, and still more preferably 14 kPa or less. The polishing load is preferably 3 kPa or more, more preferably 5 kPa or more, still more preferably 7 kPa or more, even more preferably 8 kPa or more, and even more, from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. Preferably it is 9 kPa or more. More specifically, the polishing load is preferably 3 kPa or more and 30 kPa or less, more preferably 5 kPa or more and 25 kPa or less, and even more preferably 7 kPa or more and 20 kPa or less from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. Even more preferably, it is 8 kPa or more and 18 kPa or less, still more preferably 9 kPa or more and 16 kPa or less, and even more preferably 9 kPa or more and 14 kPa or less. The polishing load can be adjusted by applying air pressure or weight to the surface plate or the substrate.

[Polishing amount in step (1)]
In the step (1), the polishing amount per unit area (1 cm ² ) of the substrate to be polished is preferably 0.20 mg or more, more preferably 0, from the viewpoint of reducing long-period defects without significantly impairing the polishing rate. .30 mg or more, more preferably 0.40 mg or more. And from the same viewpoint, 2.50 mg or less is preferable, More preferably, it is 2.00 mg or less, More preferably, it is 1.60 mg or less. More specifically, from the same viewpoint, the polishing amount is preferably 0.20 mg or more and 2.50 mg or less, more preferably 0.30 mg or more and 2.00 mg or less, and further preferably 0.40 mg or more and 1.60 mg or less. It is.

[Step (1): Polishing rate reduction rate]
In the present specification, the “polishing rate reduction rate” is a measure of the degree to which the polishing composition is held on the polishing pad, and the polishing rate when the polishing composition is allowed to flow for 4 minutes in the polishing machine is the reference rate. Then, after 4 minutes, the polishing is continued with the supply of the polishing composition being stopped, and the polishing rate 1 minute after the supply is stopped is set as the post-stop speed, and the difference between the reference speed and the post-stop speed is It is a value (%) obtained by dividing by the reference speed and multiplying by 100. Specific polishing conditions can be the polishing conditions of step (1) in the examples described later.

  The polishing liquid composition and non-spherical silica particles according to the present disclosure have a polishing rate reduction rate of 15.0% from the viewpoint of reducing long-wave waviness after rough polishing without significantly prolonging the polishing time for rough polishing. It is preferable to satisfy the following, more preferably 12.0% or less, still more preferably 8.0% or less, and still more preferably 5.0% or less.

[Supply speed of polishing composition according to the present disclosure in step (1)]
The supply rate of the polishing composition according to the present disclosure in the step (1) is preferably 2.5 mL / min or less per 1 cm ^{2 of the} substrate to be polished, more preferably 2.0 mL / min or less, more preferably from the viewpoint of economy. Preferably it is 1.5 mL / min or less, even more preferably 1.0 mL / min or less, even more preferably 0.5 mL / min or less, and even more preferably 0.2 mL / min or less. From the viewpoint of improving the polishing rate, the supply rate is preferably 0.01 mL / min or more per 1 cm ^{2 of the} substrate to be polished, more preferably 0.03 mL / min or more, further preferably 0.05 mL / min or more. is there. More specifically, the supply rate is preferably 0.01 mL / min or more and 2.5 mL / min or less per 1 cm ^{2 of the} substrate to be polished, from the viewpoints of economy and improvement of the polishing rate, and more preferably is 0.00. 03 mL / min to 2.0 mL / min, more preferably 0.03 mL / min to 1.5 mL / min, even more preferably 0.03 mL / min to 1.0 mL / min, even more preferably 0.03 mL / min. It is 05 mL / min or more and 0.5 mL / min or less, and more preferably 0.05 mL / min or more and 0.2 mL / min or less.

[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.

In one or a plurality of embodiments, the manufacturing method according to the present disclosure further includes steps (2) and (3), and steps (1) and (3) are performed by different polishing machines.
(2) A step of cleaning the substrate obtained in step (1) (cleaning step).
(3) The process of grind | polishing the grinding | polishing target surface using the polishing liquid composition B containing the silica particle B about the board | substrate obtained at the process (2).
Step (3) is a step of finishing polishing (finish polishing step) in one or a plurality of embodiments.

[Step (2)]
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. Although the cleaning method in the step (2) is not particularly limited, in one or a plurality of embodiments, the method of immersing the substrate obtained in the step (1) in the cleaning composition (cleaning method a), and the cleaning agent The method (cleaning method b) which injects a composition and supplies a cleaning composition on the surface of the board | substrate obtained by process (1) is mentioned.

[Step (2): Cleaning method a]
In the cleaning method a, the conditions for immersing the substrate in the cleaning composition are not particularly limited. For example, the temperature of the cleaning composition is 20 to 100 ° C. from the viewpoint of safety and operability. The immersion time is preferably from 10 seconds to 30 minutes from the viewpoint of the cleaning properties and production efficiency of the cleaning composition. Furthermore, from the viewpoint of enhancing the removability of the residue and the dispersibility of the residue, it is preferable that ultrasonic vibration is applied to the cleaning composition. The frequency of the ultrasonic wave is preferably 20 kHz to 2000 kHz, more preferably 40 kHz to 2000 kHz, and still more preferably 40 kHz to 1500 kHz.

[Step (2): Cleaning method b]
In the cleaning method b, from the viewpoint of promoting the cleaning performance of the residue and the solubility of the oil, the cleaning composition to which ultrasonic vibration is applied is injected to bring the cleaning composition into contact with the surface of the substrate. Or cleaning the surface by supplying the cleaning composition onto the surface of the substrate to be cleaned by injection and rubbing the surface supplied with the cleaning composition with a cleaning brush. preferable. Furthermore, as the cleaning method b, the cleaning composition to which ultrasonic vibration is applied is supplied to the surface to be cleaned by injection, and the surface to which the cleaning composition is supplied is cleaned with a cleaning brush. It is preferable to wash by rubbing.

  As means for supplying the cleaning composition onto the surface of the substrate to be cleaned, known means such as a spray nozzle can be used. There is no restriction | limiting in particular as a brush for washing | cleaning, For example, well-known things, such as a nylon brush and a PVA (polyvinyl alcohol) sponge brush, can be used. The ultrasonic frequency may be the same as the value preferably employed in the cleaning method a.

  In the step (2), in addition to the cleaning method a and / or the cleaning method b, one or more steps using known cleaning such as rocking cleaning, cleaning using rotation of a spinner, paddle cleaning, scrub cleaning, and the like are included. But you can.

[Step (2): Cleaning composition]
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.

[Step (2): Alkaline agent in cleaning composition]
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.

  The content of the alkali agent in the cleaning composition is 0.05% by mass or more and 10% by mass from the viewpoint of developing a high cleaning property with respect to the residue on the substrate of the cleaning composition and enhancing the safety during handling. The content is preferably not more than mass%, more preferably not less than 0.08 mass% and not more than 5 mass%, and still more preferably not less than 0.1 mass% and not more than 3 mass%.

  From the viewpoint of improving the dispersibility of the residue on the substrate, the pH of the cleaning composition is preferably pH 8 or more and pH 14 or less, more preferably pH 9 or more and pH 13 or less, still more preferably pH 10 or more and pH 13 or less, and even more. Preferably it is pH 11 or more and pH 13 or less. The above pH is the pH of the cleaning composition at 25 ° C., which can be measured using a pH meter, and is a value two minutes after immersion of the electrode in the cleaning composition.

[Step (2): Various additives in the 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.

  The content of the components other than water contained in the cleaning composition is a concentration that exhibits a sufficient effect for improving workability, economy, and storage stability, and a viewpoint of achieving both improvement in storage stability. From the above, when the total content of water and the content of components other than water is 100% by mass, it is preferably 10% by mass to 60% by mass, more preferably 15% by mass to 50% by mass, More preferably, it is 15 mass% or more and 40 mass% or less.

  The cleaning composition is used after being diluted. In consideration of cleaning efficiency, the dilution rate is preferably 10 to 500 times, more preferably 20 to 200 times, and still more preferably 50 to 100 times. The water for dilution may be the same as the above-mentioned polishing composition. The cleaning composition can be a concentrate based on the dilution ratio. Therefore, in the case where the cleaning composition is a concentrate based on a dilution factor, the content of components other than water contained in the cleaning composition is the sum of the content of water and the content of components other than water. Is 100% by mass, preferably 0.02% by mass to 6% by mass, more preferably 0.1% by mass to 3% by mass, and still more preferably 0.15% by mass to 1% by mass. It is as follows.

[Step (3)]
In the step (3), the polishing composition B containing silica particles and water is supplied to the polishing target surface of the substrate obtained in the step (2), the polishing pad is brought into contact with the polishing target surface, and the polishing pad And / or polishing the surface to be polished by moving the substrate 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 polishing composition used in step (3) is also referred to as polishing composition B in the present disclosure. The silica particles contained in the polishing liquid composition B are also referred to as silica particles B in the present disclosure.

  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 B]
Polishing liquid composition B used at a process (3) contains the silica particle B as an abrasive grain from a viewpoint of the protrusion defect reduction after finish grinding | polishing. The silica particles B used are preferably colloidal silica from the viewpoint of reducing long-wave waviness after finish polishing. The polishing composition B preferably does not substantially contain alumina abrasive grains from the viewpoint of reducing protrusion defects after finish polishing. The silica particles B are spherical in one or more embodiments.

  The volume average particle diameter (D50) of the silica particles B used in the polishing liquid composition B is preferably 5 nm or more and 50 nm or less, more preferably 10 nm or more and 45 nm or less, and still more preferably, from the viewpoint of reducing protrusion defects after finish polishing. Is from 15 nm to 40 nm, and more preferably from 20 nm to 35 nm. And the volume average particle diameter (D50) of the silica particle B is the volume average particle diameter of the non-spherical silica particles contained in the polishing composition in the step (1) from the viewpoint of reducing the protrusion defect after the finish polishing (D50). D50) is preferably smaller. The volume average particle diameter can be determined by the method described in Examples.

  The standard deviation of the particle diameter of the silica particles B is preferably 5 nm or more and 40 nm or less, more preferably 10 nm or more and 35 nm or less, and still more preferably 15 nm or more and 30 nm or less, from the viewpoint of reducing protrusion defects after finish polishing. The standard deviation can be obtained by the method described in the examples.

  The content of the silica particles B contained in the polishing composition B is preferably 0.5% by mass or more and 20% by mass or less, and preferably 1.0% by mass from the viewpoint of reducing long-wave waviness and protrusion defects after finish polishing. 15 mass% or less is more preferable, 3.0 mass% or more and 13 mass% or less are still more preferable, and 4.0 mass% or more and 10 mass% or less are still more preferable.

  Polishing liquid composition B contains 1 or more types chosen from the polymer which has a heterocyclic aromatic compound, a polyvalent amine compound, and an anionic group from a viewpoint of reducing the long wavelength waviness and protrusion defect after final polishing. It is preferable to include two or more types, and it is more preferable to include a heterocyclic aromatic compound, a polyvalent amine compound, and a polymer having an anionic group.

  The polishing composition B preferably contains at least one selected from acids and oxidizing agents 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. About the water used for polishing liquid composition B, pH of polishing liquid composition B, and the preparation method of polishing liquid composition B, it is the same as that of the case of the above-mentioned polishing liquid composition concerning this indication.

[Step (3): Polishing pad]
As the polishing pad used in the step (3), the same type of polishing pad as the polishing pad A used in the step (1) can be used. The average pore diameter of the pores on the surface of the polishing pad used in the step (3) is preferably 1 μm or more and 50 μm or less, more preferably 2 μm or more and 40 μm, from the viewpoint of reducing long wavelength waviness and protrusion defects after finish polishing. Hereinafter, it is more preferably 3 μm or more and 30 μm or less.

[Step (3): Polishing load]
The polishing load in the step (3) is preferably 16 kPa or less, more preferably 14 kPa or less, and still more preferably 13 kPa or less, from the viewpoint of reducing long wavelength waviness and protrusion defects after finish polishing. And from a viewpoint of reducing the long wavelength waviness and protrusion defect after final polishing, 7.5 kPa or more is preferable, More preferably, it is 8.5 kPa or more, More preferably, it is 9.5 kPa or more. More specifically, the polishing load is preferably 7.5 kPa or more and 16 kPa or less, more preferably 8.5 kPa or more and 14 kPa or less, and further preferably 9 from the viewpoint of reducing long-wave waviness and protrusion defects after finish polishing. It is from 5 kPa to 13 kPa.

[Step (3): Polishing amount]
In the step (3), the polishing amount per unit area (1 cm ² ) of the substrate to be polished and the polishing time per minute is preferably 0.02 mg or more from the viewpoint of reducing long wavelength waviness and protrusion defects after finish polishing. More preferably, it is 0.03 mg or more, More preferably, it is 0.04 mg or more. And from a viewpoint of productivity improvement, 0.15 mg or less is preferable, More preferably, it is 0.12 mg or less, More preferably, it is 0.10 mg or less. Therefore, the polishing amount is preferably 0.02 mg or more and 0.15 mg or less, more preferably 0.03 mg or more and 0.12 mg or less, and further preferably 0.04 mg or more and 0.10 mg or less from the same viewpoint as described above. .

  About the supply speed of polishing liquid composition B in a process (3), and the method of supplying polishing liquid composition B to a polisher, it is the same as that of the case of the polishing liquid composition concerning this indication in above-mentioned process (1). .

  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). Substrate to be polished in steps (1) to (3) of the polishing method of the present disclosure, the polishing liquid composition according to the present disclosure, non-spherical silica particles, polishing liquid composition B, silica particles B, polishing method and conditions, cleaning agent The composition and the cleaning method can be the same as the magnetic disk substrate manufacturing method according to the present disclosure described above. In the polishing method of the present disclosure, the step (1) and the step (3) are preferably performed by a different polishing machine.

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

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

  <1> A non-spherical silica particle, a nitrogen-containing compound, and water, wherein the non-spherical silica particle has a shape in which two or more particles are aggregated or fused, and the nitrogen-containing compound contains 2 N atoms in the molecule. Alternatively, a polishing liquid composition for a magnetic disk substrate, which is an organic amine compound having three.

<2> The non-spherical silica particles are at least one kind of silica particles selected from the group consisting of confetti-type silica particles A1, deformed-type silica particles A2, and deformed and confetti-type silica particles A3, The confetti type silica particles A1 are formed by agglomerating or fusing two or more particles different in particle size by a factor of 5 or more on the basis of the particle size of the smallest silica particles. Based on the particle size of the smallest silica particle, two or more particles having a particle size of 1.5 times or less are aggregated or fused, and the irregular and confetti-type silica particle A3 has a particle size of 1 Small particles having a particle size of 1/5 or less based on the particle size of the smallest silica particles of the aggregated or fused particles, in which two or more particles within 5 times are aggregated or fused. Are aggregated or fused shapes, <1> The polishing composition for a magnetic disk substrate according to 1>.
<3> The total content of the silica particles A1, A2, and A3 in the non-spherical silica particles is preferably 50% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and even more preferably. The polishing composition for a magnetic disk substrate according to <2>, which is 90% by mass or more.
<4> The non-spherical silica particles include at least one selected from the group consisting of confetti-type silica particles A1 and irregular-shaped silica particles A2, and the total content of silica particles A1 and silica particles A2 is non- The polishing composition for a magnetic disk substrate according to <2> or <3>, which is 80% by mass or more in spherical silica.
<5> The average particle diameter (D50) of the non-spherical silica particles is preferably 50 nm or more, more preferably 60 nm or more, still more preferably 100 nm or more, and even more preferably 110 nm or more, from <1> to <4> The polishing composition for a magnetic disk substrate according to any one of the above.
<6> The average particle diameter (D50) of the non-spherical silica particles is preferably 500 nm or less, more preferably 400 nm or less, still more preferably 300 nm or less, still more preferably 200 nm or less, and even more preferably 170 nm or less. The polishing composition for a magnetic disk substrate according to any one of <1> to <5>.
<7> The average particle diameter (D50) of the non-spherical silica particles is preferably 50 nm to 500 nm, more preferably 60 nm to 400 nm, still more preferably 100 nm to 300 nm, and even more preferably 110 nm to 200 nm. Even more preferably, the polishing composition for a magnetic disk substrate according to any one of <1> to <6>, which is 110 nm to 170 nm.
<8> The average absolute maximum length of the non-spherical silica particles is preferably 80 nm or more, more preferably 90 nm or more, still more preferably 100 nm or more, still more preferably 110 nm or more, and even more preferably 120 nm or more. The polishing composition for a magnetic disk substrate according to any one of <1> to <7>.
<9> The magnetic disk according to any one of <1> to <8>, wherein the average absolute maximum length of the non-spherical silica particles is preferably 500 nm or less, more preferably 400 nm or less, and still more preferably 350 nm or less. Polishing liquid composition for substrates.
<10> The average absolute maximum length of the non-spherical silica particles is preferably from 80 nm to 500 nm, more preferably from 90 nm to 400 nm, still more preferably from 90 nm to 350 nm, <1> to <9> A polishing composition for a magnetic disk substrate according to any one of the above.
<11> Area ratio (b / a ×) obtained by dividing the area b of a circle whose diameter is the absolute maximum length of particles obtained by electron microscope observation by the projected area a of the particles obtained by electron microscope observation and multiplying by 100 100) is preferably 30% by mass or more, more preferably 30% by mass or more and 100% by mass or less, and still more preferably 50% by mass or more and 100% by mass with respect to the total silica particles. Or less, more preferably from 70% by weight to 100% by weight, even more preferably from 80% by weight to 100% by weight, even more preferably from 90% by weight to 100% by weight, <1> to <10> A polishing composition for a magnetic disk substrate according to any one of the above.
<12> An area of a non-spherical silica particle obtained by dividing the area b of a circle whose diameter is the absolute maximum length of the particle obtained by electron microscope observation by the projected area a of the particle obtained by electron microscope observation and multiplying by 100 The average value of the rate (b / a × 100) is preferably 110% or more and 200% or less, more preferably 120% or more and 190% or less, still more preferably 130% or more and 185% or less, and even more preferably 140%. The polishing composition for a magnetic disk substrate according to any one of <1> to <11>, which is 180% or less.
<13> The BET specific surface area of the non-spherical silica particles is preferably 10 m ² / g or more and 200 m ² / g or less, more preferably 20 m ² / g or more and 100 m ² / g or less, and further preferably 30 m ² / g or more and 80 m ² or less. The polishing composition for a magnetic disk substrate according to any one of <1> to <12>, which is / g or less.
<14> The content of non-spherical silica particles 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 preferably. Is a polishing liquid composition for a magnetic disk substrate according to any one of <1> to <13>, which is 2% by mass or more.
<15> The content of non-spherical silica particles 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 or less. The polishing composition for a magnetic disk substrate according to any one of <1> to <14>.
<16> The content of non-spherical silica particles 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. The polishing composition for a magnetic disk substrate according to any one of <1> to <15>, which is 1% by mass to 20% by mass, and more preferably 2% by mass to 15% by mass.
<17> The polishing composition further contains spherical silica particles, and the mass ratio of spherical silica particles to non-spherical silica particles (spherical silica / non-spherical silica) is preferably more than 0 and 30/70 or less, more preferably. The polishing composition for a magnetic disk substrate according to any one of <1> to <16>, wherein is more than 0 and 25/75 or less, more preferably more than 0 and 20/80 or less.
<18> The polishing for a magnetic disk substrate according to any one of <1> to <17>, wherein the nitrogen-containing compound is one or a mixture thereof having any amino group from primary to tertiary. Liquid composition.
<19> 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 <18> The polishing composition for a magnetic disk substrate according to any one of 18>.
<20> The content of the nitrogen-containing compound contained in the polishing composition is preferably 0.0025% by mass or more, more preferably 0.0050% by mass or more, and further preferably 0.010% by mass or more. <1> to <19> The polishing composition for a magnetic disk substrate according to any one of <1> to <19>.
<21> The content of the nitrogen-containing compound contained 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. More preferably, it is 0.15 mass% or less, More preferably, it is 0.10 mass% or less, The polishing liquid composition for magnetic disk substrates in any one of <1> to <20>.
<22> The content of the nitrogen-containing compound contained in the polishing composition is preferably 0.0025% by mass to 1.0% by mass, more preferably 0.0025% by mass to 0.20% by mass. More preferably, it is 0.0050 mass% or more and 0.15 mass% or less, More preferably, it is 0.0050 mass% or more and 0.10 mass% or less, The magnetic in any one of <1> to <21> Polishing liquid composition for disk substrates.
<23> Content ratio of non-spherical silica particles and nitrogen-containing compound [silica particle content (mass%) / nitrogen-containing compound content (mass%)] is preferably 0.1 or more and 5000 or less. The magnetic disk according to any one of <1> to <22>, preferably 1 or more and 4000 or less, more preferably 5 or more and 2400 or less, even more preferably 40 or more and 1200 or less, and even more preferably 60 or more and 600 or less. Polishing liquid composition for substrates.
<24> The polishing composition preferably has a pH of 0.5 to 6.0, more preferably 0.7 to 4.0, still more preferably 0.9 to 3.0, and even more preferably. Is a polishing liquid composition for a magnetic disk substrate according to any one of <1> to <23>, which has a pH of 1.0 or more and a pH of 3.0 or less, and more preferably a pH of 1.0 or more and pH 2.0 or less.
<25> (1) A step of polishing the surface to be polished of the substrate to be polished using the polishing composition, (2) a step of cleaning the substrate obtained in step (1), and (3) silica particles A step of polishing the surface to be polished of the substrate obtained in the step (2) using the polishing liquid composition contained, wherein the steps (1) and (3) are steps in a polishing method performed by another polishing machine; The polishing composition for a magnetic disk substrate according to any one of <1> to <24>, which is used for polishing (1).
<26> The volume average particle diameter (D50) measured by the laser light scattering method of the silica particles contained in the polishing liquid composition in the step (3) is non-spherical contained in the polishing liquid composition in the step (1). The polishing composition for a magnetic disk substrate according to any one of <1> to <25>, which is a silica particle having a volume average particle diameter (D50) measured by a laser light scattering method of silica particles.
<27> The polishing pad in the step (1) includes a base layer and a foamed surface layer, and the compression ratio of the surface layer is 2.5% or more, and is a suede type, from <1><26> The polishing composition for a magnetic disk substrate according to any one of the above.
<28> The polishing composition for a magnetic disk substrate according to any one of <1> to <27>, wherein the magnetic disk substrate is a Ni-P plated aluminum alloy substrate.
<29> The polishing composition for a magnetic disk substrate according to any one of <1> to <28>, wherein the polishing composition further contains at least one selected from the group consisting of an acid and an oxidizing agent. object.
<30> The acid is preferably phosphoric acid, sulfuric acid, citric acid, tartaric acid, maleic acid, catechol disulfonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylene At least one selected from the group consisting of phosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) and salts thereof, more preferably sulfuric acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid) and The polishing composition for a magnetic disk substrate according to <29>, which is at least one selected from the group consisting of salts thereof, more preferably sulfuric acid.
<31> It is preferable to use a mixture of two or more of the acids and salts thereof, phosphoric acid, sulfuric acid, citric acid, tartaric acid and 1-hydroxyethylidene-1,1-diphosphonic acid, catechol disulfonic acid, and aminotri The polishing composition for a magnetic disk substrate according to <29> or <30>, wherein two or more acids selected from the group consisting of (methylenephosphonic acid) are more preferably used in combination.
<32> The acid salt is preferably a salt of the acid and at least one selected from the group consisting of metal, ammonium and alkylammonium, more preferably the acid and a metal belonging to Group 1A. Alternatively, the polishing composition for a magnetic disk substrate according to any one of <29> to <31>, which is a salt with ammonium.
<33> 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 <29> to <32>, wherein the polishing liquid composition is at least 3% and at most 3% by mass, and even more preferably at least 0.1% by mass and at most 2% by mass.
<34> The oxidizing agent is preferably at least one selected from the group consisting of hydrogen peroxide, iron nitrate (III), peracetic acid, ammonium peroxodisulfate, iron sulfate (III), and ammonium iron sulfate (III). The polishing composition for a magnetic disk substrate according to any one of <29> to <33>, which is more preferably hydrogen peroxide.
<35> The content of the oxidizing agent in the polishing composition is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and still more preferably 0.1% by mass or more. > To <34> The polishing composition for a magnetic disk substrate according to any one of the above items.
<36> The content of the oxidizing agent in the polishing composition is preferably 4% by mass or less, more preferably 2% by mass or less, and still more preferably 1.5% by mass or less. <29> to <35 > The polishing composition for a magnetic disk substrate according to any one of the above.
<37> The content of the oxidizing agent in the polishing composition is preferably 0.01% by mass to 4% by mass, more preferably 0.05% by mass to 2% by mass, and still more preferably 0.1%. The polishing composition for a magnetic disk substrate according to any one of <29> to <36>, wherein the polishing composition is <29> to <36>% by mass.
<38> (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 <37>, (2) A substrate obtained in step (1) And (3) polishing the surface to be polished of the substrate obtained in step (2) using a polishing composition containing silica particles, and the steps (1) and ( 3) is a method for manufacturing a magnetic disk substrate, which is performed by another polishing machine.
<39> The <38> description, wherein the polishing pad in the step (1) has a base layer and a foamed surface layer, and the compression rate of the surface layer is 2.5% or more and is a suede type. Manufacturing method of magnetic disk substrate.
<40> A suede type comprising the polishing liquid composition according to any one of <1> to <37>, and a base layer and a foamed surface layer, wherein the compressibility of the surface layer is 2.5% or more. The manufacturing method of a magnetic disk board | substrate including the process of grind | polishing the grinding | polishing target surface of the Ni-P plating aluminum alloy board | substrate which is a to-be-polished board | substrate using this polishing pad.
<41> The compressibility of the polishing pad is preferably 20.0% or less, more preferably 15.0% or less, still more preferably 10.0% or less, even more preferably 7.0% or less, and even more preferably. Is 5.0% or less, The method for producing a magnetic disk substrate according to <39> or <40>.
<42> The method for producing a magnetic disk substrate according to any one of <39> to <41>, wherein a surface layer of the polishing pad is made of polyurethane.
<43> The method for manufacturing a magnetic disk substrate according to any one of <39> to <42>, wherein the polishing pad is a continuous foam type polishing pad.
<44> The method for manufacturing a magnetic disk substrate according to any one of <39> to <43>, wherein the surface member of the polishing pad includes a polyurethane elastomer.
<45> A first polishing machine for polishing a substrate to be polished using the polishing composition according to any one of <1> to <37>, and a cleaning unit for cleaning the substrate polished by the first polishing machine And a second polishing machine for polishing the cleaned substrate using a polishing liquid composition containing silica particles.
<46> The polishing pad in the first polishing machine has a base layer and a foamed surface layer, and the compression ratio of the surface layer is 2.5% or more, and is a suede type. <45> The magnetic disk substrate polishing system described.
<47> The magnetic disk substrate polishing system according to <46>, wherein a surface layer of the polishing pad is made of polyurethane.
<48> The magnetic disk substrate polishing system according to <46> or <47>, wherein the polishing pad is a continuous foam type polishing pad.
<49> The polishing system for a magnetic disk substrate according to any one of <46> to <48>, wherein the surface member of the polishing pad includes a polyurethane elastomer.
<50> (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 <37>, (2) A substrate obtained in step (1) And (3) polishing the surface to be polished of the substrate obtained in step (2) using a polishing composition containing silica particles, and the steps (1) and ( 3) A method for polishing a magnetic disk substrate, which is performed by another polishing machine.
<51> The <50> description, wherein the polishing pad in the step (1) has a base layer and a foamed surface layer, and the compression ratio of the surface layer is 2.5% or more and is a suede type. Polishing method for magnetic disk substrate.
<52> The compressibility of the polishing pad is preferably 20.0% or less, more preferably 15.0% or less, still more preferably 10.0% or less, even more preferably 7.0% or less, and even more preferably. Is 5.0% or less, The method for producing a magnetic disk substrate according to <51>.
<53> The method for polishing a magnetic disk substrate according to <51> or <52>, wherein the surface layer of the polishing pad is made of polyurethane.
<54> The method for polishing a magnetic disk substrate according to any one of <51> to <53>, wherein the polishing pad is a continuous foam type polishing pad.
<55> The method for polishing a magnetic disk substrate according to any one of <51> to <54>, wherein the surface member of the polishing pad includes a polyurethane elastomer.

  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.

  A polishing liquid composition according to the present disclosure used in the step (1) and a polishing liquid composition B used in the step (3) are prepared as described below, and polishing is performed under the following conditions including the steps (1) to (3). The 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 according to the present disclosure used in step (1)]
Using the silica abrasive grains (colloidal silica particles), the following additives (organic amine compounds), acids (sulfuric acid or a mixture of sulfuric acid and phosphoric acid), oxidizing agents (hydrogen peroxide), and water shown in Table 1 The polishing liquid composition which concerns on this indication used for (1) was prepared (Examples 1-44, Reference Examples 1-8, 13 and Comparative Examples 9-12) (Tables 3-8). The content of each component in the polishing composition according to the present disclosure was colloidal silica particles: 6% by mass, additive: 0.0025-0.15% by mass, and hydrogen peroxide: 0.5% by mass. When only sulfuric acid was used as the acid, the content of sulfuric acid in the polishing composition was 0.5% by mass. When a mixture of sulfuric acid and phosphoric acid is used as the acid, the content of sulfuric acid in the polishing liquid composition is 0.2% by mass, and the content of phosphoric acid in the polishing liquid composition is 1.5% by mass. did. The pH of the polishing composition according to the present disclosure was 1.4. The colloidal silica particles of the silica abrasive grains in Table 1 are produced by the water glass method. For the silica abrasive grains 5 in Table 1, a mixture of abrasive grains 4 and abrasive grains c (abrasive grains 4 / abrasive grains c = 90/10) was used (Table 1). The pH was measured using a pH meter, and the value after 2 minutes after the electrode was immersed 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” refer to spherical particles (generally commercially available colloidal silica) that are nearly spherical.
The particle size of the silica particles is a particle size determined 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 compound that is an additive used in the polishing composition according to the present disclosure is as follows.
AEA: N- (β-aminoethyl) ethanolamine (molecular weight 104.5, number of nitrogen atoms 2): Examples 1 and 6 to 19 and Comparative Examples 10 and 12
Ethylenediamine (molecular weight 60.11, number of nitrogen atoms 2): Example 2
HEP: N- (2-hydroxyethyl) piperazine (molecular weight 130.19, number of nitrogen atoms 2): Example 3
Piperazine (molecular weight 86.14, number of nitrogen atoms 2): Examples 4, 20 to 44
DETA: Diethylenetriamine (molecular weight 103.17, number of nitrogen atoms 3): Example 5
Ethylamine (molecular weight 45.08, nitrogen atom number 1): Reference Example 2
TETA: triethylenetetramine (molecular weight 146.23, number of nitrogen atoms 4): Reference Example 3
TEPA: Tetraethylenepentamine (molecular weight 189.3, number of nitrogen atoms 5): Reference Example 4
PEHA: pentaethylenehexamine (molecular weight 232.37, number of nitrogen atoms 6): Reference Example 5
Polyethyleneimine (molecular weight 600): Reference Example 6
Polyallylamine (molecular weight 1000): Reference Example 7
DADMAC: diallyldimethylammonium chloride (molecular weight 4000): Reference Example 8
No added amine: Reference Examples 1 and 13, Comparative Examples 9 and 11

[Preparation of polishing composition B used in step (3)]
Polishing liquid composition B was prepared using the colloidal silica particle (abrasive grain d) 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 the polishing of Examples 1-44, Reference Examples 1-8, 13 and Comparative Examples 9-12.

2. Measuring method for each parameter [Volume average particle diameter of silica abrasive grains]
The silica abrasive grains were diluted with ion-exchanged water to prepare a dispersion containing 1% by mass of silica abrasive grains. The dispersion was 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.

[Method for measuring shape and area ratio 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 Corporation) was used to determine the absolute maximum length of each silica particle for 1000 to 2000 silica particle data, and the average absolute maximum length (average absolute maximum length) was calculated. Obtained. The area ratio (b / a × 100) (%) was calculated by dividing the area b of the circle having the absolute maximum length as the diameter by the projected area a of the particles obtained by electron microscope observation and multiplying by 100. And the ratio with respect to the silica abrasive grain of the particle | grains whose area ratio (b / ax100) is 110-200% was computed. Further, a value obtained by dividing the circle area b of the average absolute maximum length by the average value of the projected area a and multiplying by 100 was calculated as an average area ratio (b / a × 100).

[Measurement of average secondary particle diameter of alumina particles]
An aqueous solution containing 0.5% by mass of Poise 530 (manufactured by Kao Corporation, polycarboxylic acid type polymer surfactant) is used as a dispersion medium, and is introduced into the following measuring apparatus, and subsequently the transmittance is 75 to 95%. Then, the sample was put in, and then subjected to ultrasonic wave for 5 minutes, and then 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. This 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)
Compression ratio of surface layer: 2.5 to 15.7%
(Examples 1-16, 19, 20, 25, 30, 35, 44, Reference Examples 1-8, 13 Comparative Examples 9-12: 2.5%)
(Examples 24, 29, 34, 39, 43: 3.0%)
(Examples 23, 28, 33, 38, 42: 3.7%)
(Examples 22, 27, 32, 37, 41: 8.5%)
(Examples 17, 21, 26, 31, 36, 40: 10.2%)
(Example 18: 15.7%)
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: 6 minutes Polishing amount: 0.1-1.6 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, compression ratio of surface layer: 10.2% (manufactured by 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)]
Each substrate before and after polishing was weighed (Sartorius, “BP-210S”) and measured by introducing it into the following formula to determine the polishing amount. The value was calculated. The results are shown in Tables 3-8.
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 )
The polishing rate was evaluated in four stages according to the following criteria. The results are shown in Tables 3-8.
[Evaluation criteria]
Polishing rate (relative value): Evaluation 105 or more: “A: Excellent polishing rate and further improvement in substrate yield can be expected”
95 or more and less than 105: “B: Good polishing rate and expected improvement in substrate yield”
80 or more and less than 95: “C: Improvement is required for actual production”
Less than 80: “D: Substrate yield decreases significantly”

[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 6 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 Tables 3-8.
[Evaluation criteria]
Long-period defect occurrence rate: Evaluation 5% or less: “6: Generation is extremely suppressed and further improvement in substrate yield can be expected”
Over 5% and 10% or less: “5: Generation is extremely suppressed, and improvement in substrate yield can be expected.”
10% over 20%: "4: Real production possible"
20% over 30%: "3: Actual production needs improvement"
30% over 50%: "2: Substrate yield is greatly reduced"
50% or more: “1: Far from actual production (same level as when using general silica abrasive grains)”
[measuring equipment]
Optical interference type surface profile measuring machine: OptiFLATIII (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 stabs (pieces) on each of the four substrates by 8 to obtain the number of abrasive stabs per substrate surface (number of protrusion defects) (relative value with reference example 1 being 100). Was calculated. Tables 3 to 8 show the relative values of the number of protrusion defects and the results of evaluating the number of protrusion defects according to the following criteria.
[Evaluation criteria]
Number of protrusion defects (relative value): Evaluation: 105 or less: “A: generation is extremely suppressed and improvement in substrate yield can be expected”
Over 105 and under 120: “B: Actual production possible”
Over 120 and below 160: “C: Improvement is required for actual production”
Over 160: “D: Substrate yield decreases significantly”
5. Results The results of Examples 1 to 5, Reference Examples 1 to 8 and Comparative Examples 9 to 12 are shown in Table 3, the results of Examples 1 and 6 to 11 are shown in Table 4, and Examples 1 and 12 to 16 are used. The results are shown in Table 5, and the results of Examples 15, 17, 18 and Reference Example 13 are shown in Table 6. Table 7 shows the results of Examples 1 and 4 and Examples 19 to 20. Table 8 shows the results of Example 4, Examples 21 to 44, and Reference Example 1.

As shown in Tables 3-6, in Examples 1-18, compared with Reference Examples 1-8, 13 and Comparative Examples 9-12, without greatly impairing the polishing rate of the rough polishing in step (1), and The long-period defects (PED) after the rough polishing in the step (1) could be reduced without deteriorating the number of protrusion defects of the substrate after the final polishing in the step (3).
In Example 15 using the abrasive grains 5 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), Examples 1 to 14, Compared to 16, the polishing rate of the rough polishing in the step (1) was high, and the number of protrusion defects on the substrate after the final polishing in the step (3) was reduced.
Further, Table 6 shows the following. That is, in Example 15 and Example 17, since the polishing rate of Example 17 is 15% lower and the polishing time is fixed, the polishing amount is small. However, it can be seen that because the compressibility of the polishing pad is high, long-period defects can be reduced despite a small amount of polishing.

  As shown in Table 7, in Examples 19 to 20 where the acid used in the polishing liquid composition in step (1) is two kinds, only one kind of acid is used in the polishing liquid composition in step (1). Compared to certain Examples 1 and 4, long-period defects (PED) after rough polishing in the step (1) were further reduced. Therefore, it turns out that it is preferable to mix and use 2 or more types as an acid used for the polishing liquid composition in a process (1).

  As shown in Table 8, Examples 21 to 25 using abrasive grains 1, Examples 26 to 30 using abrasive grains 2, Examples 31 to 35 using abrasive grains 3, Examples using abrasive grains 4 In Examples 40 to 44 using 36 to 39 and Example 4, abrasive grains 5 containing non-spherical silica particles and spherical silica particles, the compressibility of the surface layer of the polishing pad in step (1) is increased. Long period defects (PED) after rough polishing in step (1) were further reduced. On the other hand, the smaller the compressibility of the surface layer of the polishing pad in the step (1), the better the polishing rate.

  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 (27)

Comprising non-spherical silica particles, a nitrogen-containing compound, and water;
The non-spherical silica particles have a shape in which two or more particles are aggregated or fused,
A polishing composition for a magnetic disk substrate, wherein the nitrogen-containing compound is an organic amine compound having 2 or 3 N atoms in the molecule (excluding ethylenediaminetetramethylenephosphonic acid and diethylenetriaminepentamethylenephosphonic acid) . The non-spherical silica particles are at least one type of silica particles selected from the group consisting of confetti-type silica particles A1, deformed-type silica particles A2, and deformed and confetti-type silica particles A3,
The confetti type silica particles A1 are formed by agglomeration or fusion of two or more particles different in particle size by a factor of 5 or more on the basis of the particle size of the smallest silica particle.
The irregular-shaped silica particle A2 is 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,
The irregular and confetti-type silica particles A3 are obtained by combining particles having two or more particles having a particle size of not more than 1.5 times with agglomeration or fusion, and further, the particle size of the smallest silica particle with the aggregation or fusion of the particles. 2. The polishing composition for a magnetic disk substrate according to claim 1, wherein small particles having a particle size of 1/5 or less on the basis of 1 are aggregated or fused.   3. The polishing composition for a magnetic disk substrate according to claim 1, wherein an average of absolute maximum lengths of the non-spherical silica particles obtained by observation with an electron microscope is 80.0 nm or more and 500.0 nm or less.   An area ratio (b / a × 100) obtained by dividing the area b of a circle having the diameter of the absolute maximum length of particles obtained by electron microscope observation by the projected area a of the particles obtained by electron microscope observation and multiplying by 100 The polishing composition for a magnetic disk substrate according to any one of claims 1 to 3, comprising silica particles of 110% or more and 200% or less in an amount of 30% by mass or more based on the total silica particles.   5. The polishing composition for a magnetic disk substrate according to claim 1, wherein the content of the nitrogen-containing compound is 0.0025 mass% or more and 0.20 mass% or less.   The polishing composition for a magnetic disk substrate according to any one of claims 1 to 5, wherein the nitrogen-containing compound is one or more compounds having any amino group from primary to tertiary. . The polishing composition for a magnetic disk substrate according to any one of claims 1 to 6, wherein the nitrogen-containing compound has a molecular weight of 60 or more and 500 or less. The polishing composition for a magnetic disk substrate according to any one of claims 1 to 7, wherein the nitrogen-containing compound is at least one selected from an aliphatic amine compound and an alicyclic amine compound. The aliphatic amine compound includes ethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, 3- (Diethylamino) propylamine, 3- (dibutylamino) propylamine, 3- (methylamino) propylamine, 3- (dimethylamino) propylamine, N-aminoethylethanolamine, N- (2-aminoethyl) diethanolamine, The polishing composition for a magnetic disk substrate according to claim 8, which is at least one selected from the group consisting of N-aminoethylisopropanolamine, N-aminoethyl-N-methylethanolamine, and diethylenetriamine. The alicyclic amine compound includes piperazine, 2-methylpiperazine, 2,5-dimethylpiperazine, 1-amino-4-methylpiperazine, N-methylpiperazine, 1- (2-aminoethyl) piperazine, hydroxyethylpiperazine, And a polishing composition for a magnetic disk substrate according to claim 8, which is at least one selected from the group consisting of piperazine-1,4-bisethanol. The polishing composition for a magnetic disk substrate according to any one of claims 1 to 10 , wherein the volume average particle diameter (D50) of the non-spherical silica particles measured by a laser light scattering method is 50 nm or more and 500 nm or less. The non-spherical silica particles contain at least one selected from the group consisting of confetti-type silica particles A1 and irregular-shaped silica particles A2, and the total content of the silica particles A1 and silica particles A2 is in the non-spherical silica particles. The polishing composition for a magnetic disk substrate according to any one of claims 2 to 11 , which is 80% by mass or more. The polishing composition for a magnetic disk substrate according to any one of claims 1 to 12 , wherein the polishing composition has a pH of 0.5 or more and 6.0 or less. (1) A step of polishing a surface to be polished of a substrate to be polished using a polishing composition, (2) a step of cleaning the substrate obtained in step (1), and (3) polishing containing silica particles Step (1) in a polishing method comprising a step of polishing the surface to be polished of the substrate obtained in Step (2) using the liquid composition, wherein Steps (1) and (3) are performed by another polishing machine. used for polishing, polishing composition for a magnetic disk substrate according to any one of claims 1 13. The volume average particle diameter (D50) measured by the laser light scattering method of the silica particles contained in the polishing liquid composition in the step (3) is that of the non-shaped silica particles contained in the polishing liquid composition in the step (1). The polishing composition for a magnetic disk substrate according to claim 14 , wherein the polishing composition is a silica particle having a volume average particle diameter (D50) measured by a laser light scattering method. The polishing pad used in the step (1) is, and the compressibility of the surface layer and a base layer and foamed surface layer is 2.5% or more, and a suede type, according to claim 14 or 15. A polishing liquid composition for a magnetic disk substrate according to 15 . The polishing composition for a magnetic disk substrate according to any one of claims 1 to 16 , wherein the magnetic disk substrate is a Ni-P plated aluminum alloy substrate. (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 claims 1 to 17 ,
(2) a step of cleaning the substrate obtained in step (1), and
(3) It has the process of grind | polishing the grinding | polishing target surface of the board | substrate obtained by process (2) using the polishing liquid composition containing a silica particle,
The method of manufacturing a magnetic disk substrate, wherein the steps (1) and (3) are performed by different polishing machines. The polishing pad used in the step (1) is, and the base layer and foamed surface layer wherein the surface layer and a compression ratio of 2.5% or more, and a suede type, according to claim 18, wherein Manufacturing method of magnetic disk substrate. Use of the polishing composition according to any one of claims 1 to 17 , and a suede type polishing pad having a base layer and a foamed surface layer, wherein the compressibility of the surface layer is 2.5% or more. A method of manufacturing a magnetic disk substrate, comprising polishing a surface to be polished of a Ni-P plated aluminum alloy substrate that is a substrate to be polished. The surface layer of the polishing pad is made of polyurethane, the production method of the magnetic disk substrate according to claim 19 or 20. The polishing pad is a polishing pad of open cell foam type, method for manufacturing a magnetic disk substrate according to any one of claims 19 21. Surface member of the polishing pad comprises a polyurethane elastomer, a manufacturing method of a magnetic disk substrate according to any one of claims 19 22. A first polishing machine for polishing of the substrate by using the polishing composition according to claims 1-17,
A cleaning unit for cleaning the substrate polished by the first polishing machine;
A magnetic disk substrate polishing system comprising: a second polishing machine that polishes a substrate after cleaning using a polishing liquid composition containing silica particles. The magnetic pad according to claim 24 , wherein the polishing pad in the first polishing machine has a base layer and a foamed surface layer, the compression rate of the surface layer is 2.5% or more, and is a suede type. Disk substrate polishing system. (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 claims 1 to 17 ,
(2) a step of cleaning the substrate obtained in step (1), and
(3) It has the process of grind | polishing the grinding | polishing target surface of the board | substrate obtained by process (2) using the polishing liquid composition containing a silica particle,
The steps (1) and (3) are a method for polishing a magnetic disk substrate, which is performed by another polishing machine. 27. The magnetic disk according to claim 26 , wherein the polishing pad in the step (1) has a base layer and a foamed surface layer, the compression rate of the surface layer is 2.5% or more, and is a suede type. A method for polishing a substrate.