TWI586795B - Polishing liquid composition for magnetic disk substrate - Google Patents

Description

Polishing fluid composition for disk substrate

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

In recent years, the disk drive has been developed in the direction of miniaturization and large capacity, and high recording density has been required. In order to achieve high recording density, it is necessary to increase the detection sensitivity of the magnetic signal. Therefore, the development of technology for further reducing the flying height of the magnetic head and reducing the unit recording area has been advanced. In order to cope with the low floating of the magnetic head and the securing of the recording area, the smoothness and flatness of the disk substrate are strictly required (reduction in surface roughness, reduction in undulation, end surface collapse) or reduction in surface defects (residual abrasive grains) , reduction of scratches, protrusions, pits, etc.). In view of the above requirements, the method of manufacturing a hard disk substrate is often a multi-stage polishing method having a polishing step of two or more stages from the viewpoint of achieving smoother surface quality and less surface quality improvement and productivity improvement. In general, in the final polishing step of the multi-stage polishing method, that is, in the fine polishing step, in order to satisfy the requirements of reduction in surface roughness, reduction in scratches, protrusions, pits, and the like, the use of colloidal cerium oxide particles is used. In the polishing liquid composition for polishing, in the polishing step (also referred to as the coarse polishing step) before the polishing step, a polishing liquid composition containing alumina particles is used from the viewpoint of improving productivity. However, in the case where alumina particles are used as the abrasive grains, there is a case where the media driver is defective due to the puncturing of the alumina particles on the substrate.

Therefore, there has been proposed a method for producing a magnetic disk substrate which can reduce the puncturing of particles to a substrate by using a polishing liquid composition containing cerium oxide particles as abrasive grains in the coarse grinding step without using alumina particles (patent Documents 1 and 2).

On the other hand, there is also a case where phosphoric acid or phosphonic acid is used as the acid contained in the polishing liquid composition (Patent Document 3).

Further, in order to increase the polishing rate of the cerium oxide particles, a cerium oxide particle having a plurality of protrusions on the surface (Patent Document 4) or beaded cerium oxide particles (Patent Document 5) has been proposed.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2014-29754

Patent Document 2: Japanese Patent Laid-Open Publication No. 2012-29755

Patent Document 3: Japanese Patent Laid-Open Publication No. 2003-147337

Patent Document 4: Japanese Patent Laid-Open Publication No. 2013-121631

Patent Document 5: Japanese Patent Laid-Open No. 2001-11433

If a coarse grinding step and a fine grinding step without using alumina particles are used in the polishing step of the disk substrate, residual alumina (for example, alumina adhesion or alumina puncturing) can be eliminated, and thus the protrusion defects are reduced. However, when it was found that the coarse grinding step was carried out by replacing the alumina particles with cerium oxide particles, there was a problem that the long-period defects could not be eliminated. In the case of a coarse grinding step using alumina particles, the problem of long-period defects generally does not occur. The elimination rate of long period defects is highly dependent on the substrate yield, so that the elimination rate of long period defects is expected to be further improved for the coarse grinding step.

Patent Document 1 discloses that when coarse non-spherical cerium oxide particles having predetermined parameters are used as coarse particles, even when substantially no alumina particles are contained, The long wavelength fluctuation after the rough grinding can be reduced without significantly increasing the grinding time of the rough grinding. However, with regard to long-period defects, a further increase in the elimination rate is expected.

Therefore, the present invention provides, in one or more embodiments, a polishing liquid composition for a magnetic disk substrate which does not have a polishing rate for rough grinding in rough grinding using non-spherical cerium oxide particles as abrasive grains. Causes greater damage and reduces long-term defects in the surface of the substrate after rough grinding.

One or a plurality of embodiments of the present invention relates to a method for producing a magnetic disk substrate, comprising (1) a step of polishing a polishing target surface of a substrate to be polished using a polishing liquid composition I, and (2) a step (1) a step of washing the substrate obtained, and (3) a step of polishing the substrate obtained in the step (2) using the polishing liquid composition II containing the ceria particle C, and performing the above steps using different grinders (1) and (3), and (i) the polishing liquid composition I of the above step (1) contains non-spherical cerium oxide particles A, spherical cerium oxide particles B, an acid, an oxidizing agent, and water, (ii) In the polishing liquid composition I of the above step (1), the mass ratio A/B of the non-spherical cerium oxide particles A to the spherical cerium oxide particles B is 80/20 or more and 99/1 or less. The total content of the non-spherical cerium oxide particles A and the spherical cerium oxide particles B in the entire cerium oxide particles is more than 98.0% by mass, and (iii) the ΔCV value of the above non-spherical cerium oxide particles A is larger than 0.0% and less than 10%, (iv) the volume of the above non-spherical cerium oxide particle A as measured by dynamic light scattering Average particle diameter (D1) and a specific surface area measured by the BET method in terms of the diameter (D2) of the particle diameter ratio (D1 / D2) of 2.00 or more and 4.00 or less, (V) The volume average particle diameter (D1) of the spherical cerium oxide particle B measured by a dynamic light scattering method is 6.0 nm or more and 80.0 nm or less, and (vi) the acid is selected from the group consisting of phosphoric acid and phosphine. At least one of the group consisting of an acid, an organic phosphonic acid, and combinations thereof.

One or a plurality of embodiments of the present invention relate to a method of polishing a disk substrate, comprising the steps (1) to (3) in the method of manufacturing a disk substrate of the present invention.

One or a plurality of embodiments of the present invention relate to a polishing system for a magnetic disk substrate, comprising: a first polishing machine for performing the polishing of the step (1) in the method for manufacturing a magnetic disk substrate of the present invention, and performing the present invention A cleaning unit for cleaning in the step (2) of the method for producing a magnetic disk substrate, and a second polishing machine for polishing the step (3) in the method for producing a magnetic disk substrate of the present invention.

One or a plurality of embodiments of the present invention relate to a polishing liquid composition for a magnetic disk substrate comprising abrasive grains, an acid, an oxidizing agent, and water, wherein the abrasive grains contain non-spherical cerium oxide particles A and spherical dioxide In the cerium particle B, the mass ratio A/B of the non-spherical cerium oxide particle A to the spherical cerium oxide particle B is 80/20 or more and 99/1 or less, and the Δ of the non-spherical cerium oxide particle A The CV value is more than 0.0% and less than 10%, and the CV90 of the non-spherical cerium oxide particle A is 20.0% or more and 40.0% or less, and the ΔCV value of the spherical cerium oxide particle B is more than 0% and 10 % or less, and the CV90 of the spherical cerium oxide particle B is 10.0% or more and 35.0% or less, and the volume average particle diameter (D1) of the non-spherical cerium oxide particle A measured by dynamic light scattering method The particle diameter ratio (D1/D2) of the specific surface area-converted particle diameter (D2) measured by the BET method is 2.00 or more and 4.00 or less, and the spherical cerium oxide particle B is measured by dynamic light scattering method. The volume average particle diameter (D1) is 6.0 nm or more and 80.0 nm or less. The acid is selected from at least one selected from the group consisting of phosphoric acid, phosphonic acid, organic phosphonic acid, and combinations thereof.

Since the method for producing a magnetic disk substrate of the present invention does not use alumina particles, the protrusion defects after the rough polishing and the fine polishing can be greatly reduced. Further, according to the method for manufacturing a magnetic disk substrate of the present invention, in one or a plurality of embodiments, the effect of not causing a large damage to the polishing speed at the time of rough polishing and the long period defect of the surface of the substrate after the rough polishing can be exhibited. The substrate yield can be improved while maintaining substrate productivity.

51‧‧‧First grinding machine

52‧‧‧cleaning unit

53‧‧‧Second grinder

Fig. 1 is an example of an electron microscope (TEM) observation photograph of a shaped colloidal cerium oxide abrasive grain.

Fig. 2 is an example of an electron microscope (TEM) observation photograph of a colloidal cerium oxide abrasive grain of a gold-plated sugar type.

Figure 3 is a graph showing the volume particle size distribution.

Fig. 4 shows an example of a result of measuring a surface of a substrate having a long period defect (PED) by an optical interference type surface shape measuring machine.

Fig. 5 is a view showing an embodiment of a polishing system.

Fig. 6 is a view showing an embodiment of a polishing step of a method of manufacturing a magnetic disk substrate.

The present invention is based on the insight that in the coarse grinding step using a polishing liquid composition containing specific non-spherical cerium oxide particles and spherical cerium oxide particles as abrasive particles, if a specific one is used in the polishing liquid composition The acid (phosphoric acid or phosphonic acid) increases the elimination rate of long-period defects and does not cause much damage to the polishing rate. In general, if the long period defects are reduced at the time of manufacture of the disk substrate, the substrate yield is improved. Therefore, according to the present invention, in one or a plurality of embodiments, the productivity of the substrate can be improved while maintaining productivity in the manufacture of the disk substrate.

The details of the mechanism for using a combination of specific non-spherical cerium oxide particles and spherical cerium oxide particles and a specific acid without causing large damage to the polishing rate and increasing the elimination rate of long-period defects are not clear. As described below. That is, the non-spherical cerium oxide particles have more voids than the spherical cerium oxide particles in the filled state due to the surface shape thereof. It is presumed that if a specific size of particles is introduced into the gap, the filling ratio of the abrasive grains is further improved in the mixed system containing a plurality of kinds of abrasive particles, and the specific non-spherical cerium oxide particles during grinding are rubbed. The resistance is moderated, thus increasing the elimination rate of long-period defects. Further, it is considered that the cutting area of the substrate is increased by the increase in the filling rate of the abrasive grains, or the load applied during polishing is more easily transmitted to the substrate, so that the polishing rate can be maintained or increased. Further, it is considered that by using phosphoric acid or phosphonic acid in the polishing composition, the corrosion inhibiting effect of phosphoric acid or phosphonic acid is utilized, and long-period defects, especially PED (polish enhanced defect) reduction efficiency, are realized with less grinding amount. Improve. In other words, the polishing rate is increased by using a specific shape of cerium oxide, and defects are suppressed by using a specific acid such as phosphoric acid, thereby achieving high quality of the substrate to be polished. In addition, it is considered that, as an advantage in the polishing step, by using abrasive grains having a high filling ratio and using a specific acid having a corrosion inhibiting effect, the polishing liquid composition acts on the substrate more efficiently, so that polishing can be performed. The supply of the liquid composition is reduced compared to the previous amount. However, the mechanism of the present invention is not limited to these.

In other words, the present invention relates to a method for producing a magnetic disk substrate (hereinafter also referred to as "the manufacturing method of the present invention"), which comprises (1) polishing a surface of a substrate to be polished using the polishing liquid composition I. a step of polishing, (2) a step of washing the substrate obtained in the step (1), and (3) grinding the substrate obtained in the step (2) using the polishing composition II containing the ceria particle C And the step (1) and (3) are carried out by using different mills, and (i) the above-mentioned slurry composition I of the above step (1) contains non-spherical cerium oxide particles A, spherical cerium oxide particles B, an acid, an oxidizing agent, and water, (ii) in the above polishing liquid composition I of the above step (1), the non-spherical cerium oxide particles A and the spherical cerium oxide particles The mass ratio (A/B) of B is 80/20 or more and 99/1 or less, and the total content of the non-spherical cerium oxide particles A and the spherical cerium oxide particles B based on the entire cerium oxide particles exceeds 98.0 by mass. %, (iii) the above-mentioned non-spherical cerium oxide particles A have a ΔCV value of more than 0.0% and less than 10%, and (iv) the above-mentioned non-spherical cerium oxide particles A are measured by dynamic light scattering method. The particle diameter ratio (D1/D2) of the volume average particle diameter (D1) to the specific surface area converted particle diameter (D2) measured by the BET method is 2.00 or more and 4.00 or less, and (v) the above spherical cerium oxide. The volume average particle diameter (D1) of the particle B measured by a dynamic light scattering method is 6.0 nm or more and 80.0 nm or less, and (vi) the acid is selected from the group consisting of phosphoric acid, phosphonic acid, organic phosphonic acid, and the like. At least one of the group consisting of the combinations. According to the manufacturing method of the present invention, in one or more embodiments, the polishing speed during the rough polishing is not greatly impaired, the protrusion defects after the finish polishing can be greatly reduced, and the surface of the substrate after the coarse polishing can be reduced. The effect of long period defects.

The "long-period defect" in the present invention includes a PED (polish enhanced defect) and a grinding flaw which are generated in the manufacturing process of the Ni-P-plated aluminum substrate. PED is a portion which is insufficiently annealed by water or foreign matter adhering to the surface of the substrate in the annealing step in the step of plating the aluminum substrate. Grinding injury refers to the sharpening of the grindstone during the grinding step (grinding step) of the aluminum substrate before plating. The long-period defect and its elimination rate can be measured in one or a plurality of embodiments using the measuring device described in the examples.

In the present invention, the "protrusion defect" means a defect on the surface of the substrate which is mainly caused by residual abrasive grains, abrasive grain adhesion, and abrasive grain puncturing after the rough polishing step and the fine polishing step. a protrusion defect on the surface of the substrate, for example, a microscopic surface of the substrate obtained by grinding The surface defect inspection apparatus such as mirror observation or scanning electron microscope observation is evaluated, and specifically, it can be evaluated by the method described in the examples.

[Non-spherical cerium oxide particles A]

The polishing liquid composition I used in the step (1) contains the non-spherical cerium oxide particles A as described above. In one or a plurality of embodiments, examples of the non-spherical cerium oxide particles A include colloidal cerium oxide, cerium oxide, and surface-modified cerium oxide. The non-spherical cerium oxide particles A are preferably colloidal cerium oxide, more preferably colloidal cerium oxide having the following specific shape, from the viewpoint of not causing significant damage to the polishing rate and reducing long-period defects. . The non-spherical cerium oxide particles A may be those produced by a flame melting method or a sol-gel method, but it is preferably a water glass method from the viewpoint of not greatly impairing the polishing rate and reducing long-period defects. The cerium oxide particles produced.

[Shape of non-spherical cerium oxide particle A]

The shape of the non-spherical cerium oxide particles A is a shape in which a plurality of particles (for example, two or more particles) are aggregated or fused, from the viewpoint of not greatly impairing the polishing rate and reducing long-period defects. In one or more embodiments, from the same viewpoint, the non-spherical cerium oxide particles A are preferably selected from the group consisting of a cerium oxide particle A1 of a glyphosose type, a cerium oxide particle A2 of a heteromorphic type, and an irregular shape. At least one of the cerium oxide particles of the group consisting of the bismuth dioxide particles A3 of the gold saccharide type is more preferably a heterogeneous cerium oxide particle A2.

In the present invention, in one or a plurality of embodiments, the bismuth dioxide particles A1 of the glyphosose type refers to cerium oxide particles having specific ridges on the surface of the spherical particles (see Fig. 2). In one or a plurality of embodiments, the cerium oxide particles A1 are formed by agglomerating or fusing two or more particles having a particle diameter of five or more times based on the particle diameter of the minimum cerium oxide particles. It is preferable that one of the particles having a small particle size is partially buried in the particle having a larger particle diameter. The above particle diameter can be used as the equivalent circle diameter measured in a particle in an electron microscope (TEM, etc.), that is, the equivalent of the area and the projected area of the particle. Determined by the long diameter of the circle. The particle diameters of the cerium oxide particles A2 and the cerium oxide particles A3 can also be determined in the same manner.

In the present invention, the heterogeneous cerium oxide particle A2 is a cerium oxide particle having a shape in which two or more particles, preferably 2 to 10 particles are aggregated or fused (see Fig. 1). In one or a plurality of embodiments, the cerium oxide particles A2 are formed by agglomerating or fusing two or more particles having a particle diameter of 1.5 or less based on the particle diameter of the minimum cerium oxide particles.

In the present invention, the bismuth dioxide particles A3 having a different shape and a ginkgo type are particles in a shape in which two or more particles are aggregated or fused. In one or more embodiments, the cerium oxide particle A3 is agglomerated or fused by agglomerated or fused particles of two or more particles having a particle diameter of 1.5 or less to agglomerate or fuse. The particle size of the cerium oxide particles is a shape obtained by a smaller particle having a particle diameter of 1/5 or less.

In one or more embodiments, the non-spherical cerium oxide particles A comprise any one of the cerium oxide particles A1, A2, and A3, or both of the cerium oxide particles A1, A2, and A3, or two. The cerium oxide particles A1, A2, and A3 are all. Regarding the ratio (content) of the cerium oxide particles A1, A2, and A3 in the total amount of the non-spherical cerium oxide particles A, it is preferable that the polishing rate is not greatly impaired and the long-cycle defects are reduced. It is 50% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and still more preferably 90% by mass or more or substantially 100% by mass.

[ΔCV value of non-spherical cerium oxide particle A]

The ΔCV value of the non-spherical cerium oxide particle A is preferably more than 0.0%, more preferably in the one or more embodiments, from the viewpoint of suppressing a decrease in the polishing rate and increasing the long-cycle defect elimination rate. 0.2% or more, further preferably 0.3% or more, and still more preferably 0.4% or more. In one or a plurality of embodiments, the ΔCV value of the non-spherical cerium oxide particles A is preferably less than 10.0%, more preferably 8.0% or less, still more preferably 7.0% or less. More preferably, it is 4.0% or less. In one or more embodiments, The ΔCV value of the non-spherical cerium oxide particles A is preferably more than 0.0% and less than 10.0%, more preferably 0.2% or more and 8.0% or less, still more preferably 0.3% or more. It is 7.0% or less, and more preferably 0.4% or more and 4.0% or less.

The ΔCV value of the so-called cerium oxide particles in the present invention means the difference between the value of the coefficient of variation (CV30) and the value of the coefficient of variation (CV90) (ΔCV=CV30-CV90), which is measured by dynamic light scattering method. The value of the angular dependence of the distribution of the scattering intensity, the value of the coefficient of variation (CV30) is the standard deviation of the particle diameter measured by the dynamic light scattering method based on the scattering intensity distribution of the detection angle of 30° (forward scattering). Divided by the average particle diameter measured by dynamic light scattering based on the scattering intensity distribution of the detection angle of 30° and multiplied by 100, the value of the above coefficient of variation (CV90) is based on the detection angle 90 by dynamic light scattering. The standard deviation of the particle diameter measured by the scattering intensity distribution of ° (side scattering) is obtained by dividing the average particle diameter measured by dynamic light scattering based on the scattering intensity distribution of the detection angle of 90° and multiplying by 100. The ΔCV value can be specifically measured by the method described in the examples.

The present inventors considered that the method of expressing the characteristics of the non-spherical cerium oxide particles is based only on the use of the above-described average particle diameter (D1) and the average particle diameter (D1) measured by dynamic light scattering method. The previous findings that the particle size ratio (D1/D2) of the specific surface area converted particle diameter (D2) measured by the BET method are expressed do not express the polishing performance of the cerium oxide particles. The inventors have further studied and found that the ΔCV value is an effective method for understanding the state of the non-spherical cerium oxide particles in the entire system (block), and by focusing on these parameters, it is possible to suppress the previously unknown The range of the non-spherical cerium oxide which is reduced in the polishing rate, the long-cycle defect elimination rate, and the reduction of the protrusion defects is accurately specified. That is, the non-spherical cerium oxide particles have different ΔCV values depending on the degree of irregularity, and the ΔCV value can be an index indicating the degree of irregularity of the non-spherical cerium oxide particles. For example, if the degree of irregularity of the non-spherical cerium oxide particles becomes high, pseudo multiple scattering (self-scattering) is likely to occur, and the angular dependence of the scattering intensity distribution measured by the dynamic light scattering method becomes small, and the ΔCV value becomes small. .

The term "scattering intensity distribution" as used in the present invention means dynamic light scattering (DLS: Dynamic Light Scattering) or particle size distribution of three kinds of particle size distribution (scattering intensity, volume conversion, number conversion) of particles below submicron obtained by QS (Ouasi-elastic Light Scattering) distributed.

[Volume average particle diameter (D1) of non-spherical cerium oxide particle A as measured by dynamic light scattering method]

The volume average particle diameter (D1) of the non-spherical cerium oxide particles A is preferably 120.0 nm or more in terms of suppressing a decrease in the polishing rate and increasing the long-period defect elimination rate in one or a plurality of embodiments. And less than 300.0nm. In one or a plurality of embodiments, the volume average particle diameter (D1) of the non-spherical cerium oxide particles A is preferably 120.0 nm or more, more preferably 150.0 nm or more, and further preferably 160.0 nm or more, more preferably 170.0 nm or more, still more preferably 180.0 nm or more, still more preferably 190.0 nm or more, and still more preferably 200.0 nm or more. In one or a plurality of embodiments, the volume average particle diameter (D1) of the non-spherical cerium oxide particles A is preferably less than 300.0 nm, more preferably less than 260.0 nm, and more preferably The ratio is less than 250.0 nm, more preferably less than 220.0 nm, and even more preferably less than 210.0 nm. In one or a plurality of embodiments, the volume average particle diameter (D1) of the non-spherical cerium oxide particles A is preferably 120.0 nm or more and less than 260.0 nm, more preferably 150.0 nm or more. And not more than 260.0 nm, further preferably 160.0 nm or more and less than 260.0 nm, more preferably 170.0 nm or more and less than 260.0 nm, further preferably 180.0 nm or more and less than 250.0 nm, and more preferably 190.0. Above nm and not up to 220.0 nm, more preferably 200.0 nm or more and less than 210.0 nm.

The volume average particle diameter (D1) of the cerium oxide particles in the present invention means an average particle diameter based on a scattering intensity distribution measured by a dynamic light scattering method, and the so-called cerium oxide particles are not particularly described. The average particle diameter refers to an average particle diameter based on a scattering intensity distribution measured by a dynamic light scattering method to detect an angle of 90°. The volume average particle diameter (D1) of the cerium oxide particles in the present invention can be specifically obtained by the method described in the examples.

[Non-spherical cerium oxide particle A particle size ratio (D1/D2)]

The ratio of the volume average particle diameter (D1) measured by the dynamic light scattering method to the specific surface area converted particle diameter (D2) measured by the BET method for the non-spherical cerium oxide particle A (D1) /D2), in one or a plurality of embodiments, from the viewpoint of suppressing a decrease in the polishing rate and increasing the long-period defect elimination rate, it is preferably 2.00 or more, more preferably 2.50 or more, still more preferably 3.00 or more, and further More preferably, it is 3.50 or more. In one or a plurality of embodiments, the particle diameter ratio (D1/D2) of the non-spherical cerium oxide particles A is preferably 4.00 or less, more preferably 3.90 or less, still more preferably 3.80. the following. In one or a plurality of embodiments, the particle diameter ratio (D1/D2) of the non-spherical cerium oxide particles A is preferably 2.00 or more and 4.00 or less, more preferably 2.50 or more and 3.90 or less. Further, it is preferably 3.00 or more and 3.90 or less, and more preferably 3.50 or more and 3.80 or less.

In the present invention, the specific surface area converted particle diameter (D2) of the cerium oxide particles is a specific surface area S (m ² /g) measured by a nitrogen adsorption method (BET method), according to D2 = 2720 / S [nm It is obtained by the formula.

The particle size ratio (D1/D2) of the volume average particle diameter (D1) measured by the dynamic light scattering method and the specific surface area converted particle diameter (D2) measured by the BET method may mean cerium oxide particles. The degree of alienation of A. In general, regarding the volume average particle diameter (D1) measured by the dynamic light scattering method, when the cerium oxide particles are shaped particles, the light scattering in the long direction is detected and processed, so that consideration is given. The length to the long direction and the short direction, the greater the degree of the shape, the larger the value. The specific surface area converted particle diameter (D2) measured by the BET method is expressed by a sphere in which the volume of the particles to be determined is used as a reference, and therefore the value is smaller than D1. From the viewpoint of the polishing rate, the particle diameter ratio (D1/D2) is preferably larger in the above range.

[N-spherical cerium oxide particle A of CV90]

The CV90 of the non-spherical cerium oxide particle A is preferably 20.0% or more, and more preferably 25.0% from the viewpoint of suppressing a decrease in the polishing rate and an increase in the long-cycle defect elimination rate in one or a plurality of embodiments. The above is further preferably 27.0% or more. From the same viewpoint, it is preferably 40.0% or less, more preferably 38.0% or less, further preferably 35.0% or less, and still more preferably 32.0% or less. In one or a plurality of embodiments, the CV90 of the non-spherical cerium oxide particles A is 20.0% or more and 40.0% or less, preferably 25.0% or more and 38.0% or less, and more preferably 25.0%. The above is 35.0% or less, and more preferably 27.0% or more and 32.0% or less.

The CV90 system of the cerium oxide particles in the present invention uses the value of the coefficient of variation based on the standard deviation of the scattering intensity distribution divided by the average particle diameter and multiplied by 100 in the dynamic light scattering method, and refers to a detection angle of 90° (side scattering). The measured CV value. The CV90 of the cerium oxide particle A can be specifically obtained by the method described in the examples.

[CV30 of non-spherical cerium oxide particle A]

The CV30 of the non-spherical cerium oxide particles A is preferably in the same range as the range disclosed in the above CV90. It is important to appropriately set it within the range of the relationship with the ΔCV value (= CV30 - CV90).

[Content of non-spherical cerium oxide particle A in the polishing liquid composition I]

The content of the non-spherical cerium oxide particles A in the polishing liquid composition I is preferably 0.1 mass in terms of suppressing a decrease in the polishing rate and an increase in the long-cycle defect elimination rate in one or a plurality of embodiments. % or more is more preferably 0.5% by mass or more, further preferably 1% by mass or more, and still more preferably 2% by mass or more. From the viewpoint of economy, the content is preferably 30% by mass or less, more preferably 25% by mass or less, 20% by mass or less, more preferably 15% by mass or less. With respect to the content of the non-spherical cerium oxide particles A in the polishing liquid composition I, in one or a plurality of embodiments, from the viewpoints of suppressing the decrease in the polishing rate and the improvement of the long-cycle defect elimination rate, and the economy, It is preferably 0.1% by mass or more and 30% by mass or less, more preferably 0.5% by mass or more and 25% by mass or less, further preferably 1% by mass or more and 20% by mass or less, and more preferably 2% by mass or more and 15 parts by mass or more. Below mass%.

[Manufacturing method of non-spherical cerium oxide particle A]

The non-spherical cerium oxide particle A is preferably a water glass method from the viewpoints of a decrease in the polishing rate during the coarse polishing and a long period defect elimination rate and a reduction in the protrusion defects after the coarse polishing and the fine polishing. The cerium oxide particles produced by the particle growth method of the ceric acid alkali salt aqueous solution as a starting material are not produced by a flame melting method, a sol-gel method or a pulverization method. The form of use of the non-spherical cerium oxide particles A is preferably a slurry.

The cerium oxide particles are usually obtained by the following methods (for example, Japanese Patent Laid-Open Publication No. SHO-47-1964, Japanese Patent Laid-Open No. Hei 1-23412, Japanese Patent Publication No. Hei 4-55125, Japanese Patent Special Fair 4-55127 (1), that is, 1) a mixture (seed liquid) of sodium citrate No. 3 and seed particles (small particle size cerium oxide) of less than 10% by mass is placed in a reaction tank, and the seed liquid is heated to 60. More than °C to make it mature; 2) Adding the acidic active citric acid aqueous solution and alkali (alkali metal or quaternary ammonium) prepared by passing the sodium citrate No. 3 through the cation exchange resin to the seed liquid to keep the pH constant. The spherical particles (seed particles) are grown; 3) The mixed solution in the reaction tank is matured and then concentrated by evaporation or ultrafiltration. However, a large number of reports have produced non-spherical cerium oxide particles A if the steps are changed in the same order. For example, the chemical nature of the active tannic acid is extremely unstable. Therefore, if a polyvalent metal ion such as Ca or Mg is added to the mixed liquid designed in the reaction tank, an elongated shape of the cerium oxide sol can be produced. Further, by changing the temperature of the reactant (mixed liquid in the reaction tank) (if the liquid temperature exceeds the boiling point of water, the water in the mixed liquid evaporates, the cerium oxide is dried at the sputum interface), and the pH of the reactant (If the pH of the mixed solution is 9 or less, the cerium oxide particles are liable to be linked), the SiO ₂ /M ₂ O (M is an alkali metal or quaternary ammonium) in the reactant, and the molar ratio thereof When the ratio is 30 to 60, the non-spherical cerium oxide is selectively formed, and the non-spherical cerium oxide particles can be produced (for example, Japanese Patent Publication No. Hei 8-5-1657, Japanese Patent No. 2803134, and Japanese Patent No. Japanese Laid-Open Patent Publication No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. Opened the bulletin 2011-16702). Among them, the method for producing the non-spherical cerium oxide particles A is not limited to these.

The method of adjusting the particle size distribution of the non-spherical cerium oxide particles A is not particularly limited, and examples thereof include a method of realizing a desired particle size distribution by adding particles which become new nuclei during the growth of the particles in the production stage. Or a method of mixing two or more kinds of cerium oxide particles having different particle diameter distributions to achieve a desired particle size distribution.

[Spherical cerium oxide particles B]

The polishing liquid composition I used in the step (1) contains spherical cerium oxide particles B as described above. In one or a plurality of embodiments, examples of the spherical cerium oxide particles B include colloidal cerium oxide, cerium oxide, and surface-modified cerium oxide. The spherical cerium oxide particles B are preferably colloidal cerium oxide from the viewpoint of suppressing the decrease in the polishing rate, increasing the long-period defect elimination rate, and reducing the protrusion defects.

In the "spherical cerium oxide particles" of the present invention, in one or a plurality of embodiments, in view of suppressing a decrease in the polishing rate and an increase in the long-period defect elimination rate, particles having a spherical shape and a spherical shape can be used. For example, a sphericity of 0.9 to 1.1 can be used. In one or a plurality of embodiments, the "spherical cerium oxide particles" may be a commercially available colloidal cerium oxide.

In one or more embodiments, the spherical cerium oxide particles B may be a spherical cerium oxide particle or a combination of two or more spherical cerium oxide particles. In the case where the spherical cerium oxide particles B are a combination of two or more spherical cerium oxide particles, in one or a plurality of embodiments, each spherical cerium oxide particle satisfies the description of the present invention. Necessary conditions for spherical cerium oxide particles B". In one or a plurality of embodiments, the spherical cerium oxide particles B preferably use two or more kinds of particles having different particle diameters from the viewpoint of suppressing a decrease in the polishing rate and an increase in the long-period defect elimination rate.

[ΔCV value of spherical cerium oxide particle B]

The ΔCV value of the spherical cerium oxide particle B is preferably large in terms of suppressing a decrease in the polishing rate and an increase in the long-cycle defect elimination rate in one or a plurality of embodiments. It is 0.0%, more preferably 0.2% or more, further preferably 0.3% or more, and still more preferably 0.4% or more. In one or a plurality of embodiments, the ΔCV value of the spherical cerium oxide particles B is preferably 10% or less, more preferably less than 10.0%, still more preferably 8.0% or less. Further, it is more preferably 7.0% or less, and still more preferably 4.0% or less. In one or a plurality of embodiments, the ΔCV value of the spherical cerium oxide particles B is preferably greater than 0.0% and 10% or less, more preferably greater than 0.0% and less than 10.0%, from the viewpoint of the same ΔCV value. Further, it is preferably 0.2% or more and 8.0% or less, more preferably 0.3% or more and 7.0% or less, and still more preferably 0.4% or more and 4.0% or less.

[Volume average particle diameter (D1) measured by dynamic light scattering method of spherical cerium oxide particle B]

The volume average particle diameter (D1) of the spherical cerium oxide particles B is 6.0 nm or more and 80.0 nm or less from the viewpoint of suppressing a decrease in the polishing rate and an increase in the long period defect elimination rate. In one or a plurality of embodiments, the volume average particle diameter (D1) of the spherical cerium oxide particles B is 6.0 nm or more from the viewpoint of the same, and preferably 7.0 nm or more. In one or a plurality of embodiments, the volume average particle diameter (D1) of the spherical cerium oxide particles B is 80.0 nm or less, preferably 70.0 nm or less, and more preferably 60.0 nm or less. In one or a plurality of embodiments, the volume average particle diameter (D1) of the spherical cerium oxide particles B is 6.0 nm or more and 80.0 nm or less, preferably 6.0 nm or more and 70.0 nm or less from the viewpoint of the same. More preferably, it is 7.0 nm or more and 60.0 nm or less.

As described above, in the one or more embodiments, the spherical cerium oxide particles B contained in the polishing liquid composition I are preferably used in terms of suppressing a decrease in the polishing rate and an increase in the long-cycle defect elimination rate. Particles of two or more different diameters. The combination of the two types is not limited, and one or a plurality of embodiments include spherical particles having a volume average particle diameter (D1) of 6.0 nm or more and 15.0 nm or less and a spherical shape of 15.5 nm or more and 70.0 nm or less. The combination of particles or a combination of spherical particles of 15.5 nm or more and 30.0 nm or less and spherical particles of 30.5 nm or more and 70.0 nm or less.

[Size ratio of spherical cerium oxide particle B (D1/D2)]

The ratio of the volume average particle diameter (D1) measured by the dynamic light scattering method to the specific surface area converted particle diameter (D2) measured by the BET method for the spherical cerium oxide particle B (D1/) In one or a plurality of embodiments, from the viewpoint of suppressing a decrease in the polishing rate and increasing the long-period defect elimination rate, it is preferably 1.00 or more, more preferably 1.10 or more, still more preferably 1.15 or more. In one or a plurality of embodiments, the particle diameter ratio (D1/D2) of the spherical cerium oxide particles B is preferably 1.50 or less, more preferably 1.40 or less, still more preferably 1.30 or less. . The particle diameter ratio (D1/D2) of the spherical cerium oxide particles B is 1.00 or more and 1.50 or less, preferably 1.10 or more and 1.40 or less, more preferably in one or a plurality of embodiments. 1.15 or more and 1.30 or less.

[CV90 of spherical cerium oxide particle B]

In one or a plurality of embodiments, the CV90 of the spherical cerium oxide particles B is preferably 10.0% or more, and more preferably 15.0% or more from the viewpoint of suppressing a decrease in the polishing rate and increasing the long-period defect elimination rate. Further, it is preferably 20.0% or more, and from the same viewpoint, it is preferably 35.0% or less, more preferably 32.0% or less, still more preferably 30.0% or less. In one or a plurality of embodiments, the CV90 of the spherical cerium oxide particles B is 10.0% or more and 35.0% or less, preferably 15.0% or more and 32.0% or less, and more preferably 20.0% or more. And 30.0% or less.

[Content of spherical cerium oxide particle B in the polishing liquid composition I]

The content of the spherical cerium oxide particles B in the polishing liquid composition I is preferably 0.01% by mass in terms of suppressing a decrease in the polishing rate and an increase in the long-cycle defect elimination rate in one or a plurality of embodiments. The above is more preferably 0.05% by mass or more, further preferably 0.1% by mass or more, and still more preferably 0.2% by mass or more. The content is preferably 3% by mass or less, more preferably 2.5% by mass or less, further preferably 2% by mass or less, and still more preferably 1.5% by mass or less, from the viewpoint of economy.

[Method of Manufacturing Spherical Cerium Oxide Particle B]

The spherical cerium oxide particles B are preferably aqueous solution of ceric acid alkali salt from the viewpoints of suppression of the decrease in the polishing rate during the coarse polishing and the long-cycle defect elimination rate and the reduction of the protrusion defects after the coarse polishing and the fine polishing. The cerium oxide particles produced by the particle growth method as a starting material are not produced by a flame melting method, a sol-gel method or a pulverization method. The form of use of the spherical cerium oxide particles B is preferably a slurry.

[Overlapping frequency of volume particle size distribution of non-spherical cerium oxide particles A and spherical cerium oxide particles B]

Regarding the total of the overlapping frequency of the volume particle size distribution of the non-spherical cerium oxide particles A and the spherical cerium oxide particles B in the polishing liquid composition I, in one or a plurality of embodiments, the polishing rate is suppressed from decreasing. From the viewpoint of increasing the long-period defect elimination rate, it is preferably 0% or more and 50% or less, more preferably 10% or more and 45% or less, further preferably 15% or more and 40% or less, and still more preferably 20% or more. More than % and less than 35%. The overlapping frequency of the volume particle size distribution of the non-spherical cerium oxide particles A and the spherical cerium oxide particles B can be specifically obtained by the method described in the examples. It is presumed that the above effects are obtained by a suitable balance between the void ratio and the smaller particles present in the voids in the mixture of cerium oxide particles of different sizes.

[Mass ratio of non-spherical cerium oxide particles A to spherical cerium oxide particles B in the polishing liquid composition I]

Regarding the mass ratio (A/B) of the content of the non-spherical cerium oxide particles A and the spherical cerium oxide particles B in the polishing liquid composition I, the polishing rate is suppressed in one or a plurality of embodiments. The viewpoint of lowering and increasing the long-period defect elimination rate is 80/20 or more, preferably 85/15 or more, and more preferably 88/12 or more. In one or a plurality of embodiments, the mass ratio (A/B) of the non-spherical cerium oxide particles A to the spherical cerium oxide particles B is 99/1 or less, preferably 95/. 5 or less, more preferably 92/8 or less. In the case where the spherical cerium oxide particles B are a combination of two or more spherical cerium oxide particles, the content of the spherical cerium oxide particles B means the total content of the particles. Non-spherical cerium oxide particle A The content is also the same.

[Content of other cerium oxide particles in the polishing liquid composition I]

In the case where the polishing liquid composition I contains cerium oxide particles other than the spherical cerium oxide particles A and the spherical cerium oxide particles B in one or a plurality of embodiments, the polishing liquid composition I The total content of the non-spherical cerium oxide particles A and the spherical cerium oxide particles B in the entire cerium oxide particles is more than 98.0% by mass from the viewpoint of suppressing the decrease in the polishing rate and the long-cycle defect elimination rate. The amount is preferably 98.5 mass% or more, more preferably 99.0 mass% or more, further preferably 99.5% by mass or more, more preferably 99.8% by mass or more, and still more preferably 100% by mass.

[acid]

The polishing liquid composition I contains at least one selected from the group consisting of phosphoric acid, phosphonic acid, organic phosphonic acid, and combinations thereof, from the viewpoint of not causing substantial damage to the polishing rate and reducing long-period defects. acid. The use of the acid in the slurry composition I includes the use of an acid and/or a salt thereof.

The "phosphoric acid" in the present invention means phosphoric acid and other similar compound groups having a phosphate skeleton. In one or a plurality of embodiments, pyrophosphoric acid is exemplified as the above-mentioned similar compound group. In the present invention, inorganic phosphoric acid is exemplified as "phosphoric acid" in one or a plurality of embodiments unless otherwise specified. In the present invention, inorganic phosphonic acid is exemplified as "phosphonic acid" in one or a plurality of embodiments unless otherwise specified.

The "organic phosphonic acid" of the present invention may, in one or more embodiments, be 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), or an amine. Base three (methylene phosphonic acid), ethylene diamine tetra (methylene phosphonic acid), di-ethyltriamine penta (methylene phosphonic 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, methane hydroxyphosphonic acid , 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, α-methylphosphinosuccinic acid, and combinations thereof.

The phosphoric acid, the phosphonic acid, the organic phosphonic acid, and the salts thereof may be used singly or in combination of two or more. As the acid of the polishing liquid composition I, in one or a plurality of embodiments, phosphoric acid or HEDP is preferable from the viewpoint of not greatly impairing the polishing rate and reducing long-period defects.

In the case of using the salt of the acid, it is not particularly limited, and specific examples thereof include a metal, ammonium, alkylammonium, and the like. Specific examples of the metal include metals belonging to the periodic table (long-period type) 1A, 1B, 2A, 2B, 3A, 3B, 4A, 6A, 7A or 8.

The content of the above-mentioned acid in the polishing liquid composition I is preferably 0.001% by mass or more and 5.0% by mass or less, more preferably 0.01%, from the viewpoint of not greatly impairing the polishing rate and reducing long-period defects. % or more and 4.0% by mass or less, more preferably 0.05% by mass or more and 3.0% by mass or less, still more preferably 0.1% by mass or more and 2.5% by mass or less.

The polishing composition I may contain an acid different from phosphoric acid, phosphonic acid, and organic phosphonic acid in one or more embodiments within a range that does not impair the effect.

As the acid different from the phosphoric acid, the phosphonic acid and the organic phosphonic acid, other inorganic acids are preferred. Examples of the "other inorganic acid" in the present invention include nitric acid, sulfuric acid, sulfurous acid, persulfuric acid, hydrochloric acid, perchloric acid, and aminosulfonic acid. In one or a plurality of embodiments, sulfuric acid is preferred from the viewpoint of not greatly impairing the polishing rate and reducing long-period defects.

The content of the above-mentioned other inorganic acid in the polishing liquid composition I is preferably 0.001% by mass or more and 0.6% by mass or less from the viewpoint of not greatly impairing the polishing rate and reducing long-term defects, and more preferably 0.01% by mass or more and 0.5% by mass or less, more preferably 0.05% by mass or more and 0.4% by mass or less, still more preferably 0.1% by mass or more and 0.3% by mass or less.

[oxidant]

The polishing liquid composition I contains an oxidizing agent from the viewpoint of not greatly impairing the polishing rate and reducing long-period defects. Examples of the oxidizing agent include a peroxide, permanganic acid or a salt thereof, chromic acid or a salt thereof, a peroxy acid or a salt thereof, an oxo acid or a salt thereof. Among these, hydrogen peroxide, iron (III) nitrate, peracetic acid, ammonium peroxodisulfate, iron (III) sulfate, and iron (III) sulfate are preferred, and the polishing rate is improved and the surface is not. From the viewpoint of adhesion of metal ions, versatility, and low price, hydrogen peroxide is more preferable. These oxidizing agents may be used singly or in combination of two or more.

The content of the oxidizing agent in the polishing liquid composition I 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, from the viewpoint of improving the polishing rate. The content is preferably 4.0% by mass or less, more preferably 2.0% by mass or less, and still more preferably 1.5% by mass or less from the viewpoint of not greatly impairing the polishing rate and reducing long-term defects. The content is preferably 0.01% by mass or more and 4.0% by mass or less, more preferably 0.05% by mass or more and 2.0% by mass or less, and further preferably from the viewpoint of not greatly impairing the polishing rate and reducing long-term defects. It is 0.1% by mass or more and 1.5% by mass or less.

[Other ingredients]

Other components may be adjusted in the slurry composition I as needed. Examples of other components include a tackifier, a dispersant, a rust preventive, an alkaline substance, a polishing rate improver, a surfactant, and a polymer compound. These other optional components are preferably formulated in the polishing liquid composition I within the range which does not impair the effects of the present invention, and the total content of any of the components in the polishing liquid composition I is preferably 10% by mass or less, more preferably 5 Below mass%.

[water]

The slurry composition I contains water as a medium. As the water, distilled water, ion-exchanged water, pure water, ultrapure water, or the like can be used. In order to make the polishing liquid composition easy to use, the content of the water in the polishing composition I 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, and further preferably 80% by mass or more and 97 quality The amount is 5% or less, and more preferably 85% by mass or more and 97% by mass or less.

[Alumina abrasive grains]

The polishing liquid composition I preferably contains substantially no alumina abrasive grains from the viewpoint of reducing the protrusion defects. In the present invention, the term "substantially free of alumina abrasive grains" may include, in one or more embodiments, alumina particles which do not contain alumina particles and which do not function as abrasive grains, or Contains no amount of alumina particles that will affect the grinding results. The specific content of the alumina particles in the polishing liquid composition I is not particularly limited, and is preferably 5% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less, based on the entire polishing grains. More preferably, it is substantially 0%.

[pH]

The pH of the polishing composition I is preferably adjusted to 0.5 or more and 6.0 or less by using the above-mentioned acid or a known pH adjuster without deteriorating the polishing rate and reducing long-term defects. It is more preferably 0.7 or more and 4.0 or less, still more preferably 0.9 or more and 3.0 or less, still more preferably 1.0 or more and 3.0 or less, still more preferably 1.2 or more and 2.5 or less, still more preferably 1.4 or more and 2.0 or less. The pH value of the polishing liquid composition at 25 ° C can be measured using a pH meter, and the electrode is immersed in the polishing composition for 2 minutes.

[Preparation method of polishing liquid composition I]

The polishing liquid composition I can be prepared, for example, by mixing non-spherical cerium oxide particles A, spherical cerium oxide particles B, the above-mentioned acid, the above oxidizing agent, water, and other components as needed, by a known method. In the present invention, the "content of the component contained in the polishing liquid composition" means the content of the above component when the polishing composition is used for polishing. Therefore, in the case where the polishing liquid composition is produced in the form of a concentrate, the content of the above components may become higher in accordance with the concentration. The above mixing is not particularly limited, and it can be carried out using a mixer such as a homogenizer, a homomixer, an ultrasonic disperser, or a wet ball mill.

Therefore, the present invention relates to the manufacture of a polishing composition I in other aspects. The method comprises the steps of: (1) ΔCV value greater than 0.0% and less than 10%, volume average particle diameter (D1) measured by dynamic light scattering method and measured by BET method The particle diameter ratio (D1/D2) of the specific surface area-converted particle diameter (D2) is 2.00 or more and 4.00 or less of the non-spherical cerium oxide particles A, and (2) the volume average particle diameter (D1) is 6.0 nm or more and 80.0 nm. The spheroidal cerium oxide particles B and (3) below are at least one selected from the group consisting of phosphoric acid, phosphonic acid, organic phosphonic acid, and the salts thereof, and combinations thereof, and (4) an oxidizing agent. (5) Water, the mass ratio (A/B) of the non-spherical cerium oxide particles A and the spherical cerium oxide particles B is 80/20 or more and 99/1 or less with respect to the entire cerium oxide particles. The total content of the non-spherical cerium oxide particles A and the spherical cerium oxide particles B was more than 98.0% by mass. The content of each component can be set as described above.

[ground substrate to be polished]

The substrate to be used for polishing the substrate-based magnetic disk substrate or the magnetic disk substrate by the polishing liquid composition I may be, for example, a Ni-P-plated aluminum alloy substrate, or a tantalum glass or an aluminosilicate glass. A glass substrate such as crystallized glass or tempered glass. Among them, the substrate to be polished used in the present invention is preferably a Ni-P-plated aluminum alloy substrate from the viewpoint of strength and ease of handling. The shape of the substrate to be polished is not particularly limited, and may be, for example, a shape having a flat portion such as a disk shape, a plate shape, a block shape, or a prismatic shape, or a shape having a curved surface portion such as a lens. Among them, a dish-shaped substrate to be polished is preferable. 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 thereof is, for example, about 0.5 to 2 mm.

[Method of Manufacturing Disk Substrate]

In general, the magnetic disk system grinds the glass substrate subjected to the lapping step or the aluminum alloy substrate subjected to the Ni-P plating step by a rough grinding step and a fine grinding step, and is subjected to a recording portion forming step. It is made by disk. The method for producing a magnetic disk substrate of the present invention has the following steps (1) to (3), and the steps (1) and (3) are manufactured by using different grinding machines.

(1) Rough grinding step: a step of polishing the substrate to be polished using the above-described polishing liquid composition I.

(2) Washing step: a step of washing the substrate obtained in the step (1).

(3) Fine polishing: a step of polishing the substrate obtained in the step (2) using a polishing liquid composition containing cerium oxide particles C (hereinafter also referred to as " polishing liquid composition II").

[Step (1): rough grinding step]

In the step (1), in one or more embodiments, the polishing target composition is used to polish the polishing target surface of the substrate to be polished, and in one or more of the embodiments, the following steps are performed: The liquid composition I is supplied to the polishing target surface of the substrate to be polished, and a polishing pad (hereinafter also referred to as "polishing pad A") is brought into contact with the polishing target surface to move at least one of the polishing pad and the substrate to be polished. The surface of the object to be polished is ground. 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. Examples of the substrate to be polished in the step (1) include the substrate to be polished.

[Step (1) of the polishing pad A]

The polishing pad A used in the step (1) of the production method of the present invention is a suede type having a base layer and a foamed surface layer from the viewpoint of not greatly impairing the polishing rate and reducing long-period defects. In the polishing pad, the surface layer has a compression ratio of 2.5% or more.

<Configuration of polishing pad A>

Regarding the foamed layer as the surface layer of the polishing pad A, in one or a plurality of embodiments, an independent foaming type and a continuous foaming type can be used, and from the viewpoint of the discharge property of the polishing dust, it is preferably used. Continuous foaming type. As a continuous foaming type polishing pad, for example, "Basic and Example of the 2nd Chemical Mechanical Polishing (CMP) of the CMP Technology Basic Series Lecture (Matt Pad), May 27, 1998, Globalnet Co., Ltd. Edited, or "Science of CMP, Kashiwa Masahiro, Science Forum, Inc., Chapter 4". Here, the so-called suede type, in one or a plurality of embodiments A structure having a base layer and a foamed layer having a spindle-shaped pore perpendicular to the base layer as described in Japanese Laid-Open Patent Publication No. Hei 11-335979.

In one or more embodiments, the suede type polishing pad is manufactured by the following method. Applying a solution obtained by dissolving a polyurethane elastomer in a solvent such as dimethylformamide (DMF) onto a base layer containing polyethylene terephthalate (PET), and immersing it in water Or wet-solidification in a mixed solution of water and a solvent of a polyurethane elastomer solution, washing with water, and drying to effect solvent removal. Thereby, a foamed layer having a spindle-shaped pore perpendicular to the base layer is formed on the base layer. Then, the surface of the obtained foamed layer is ground by sandpaper or the like, whereby a suede type polishing pad having a pore portion on its surface and having a foamed layer having a spindle-shaped pore perpendicular to the base layer is obtained.

<Material of polishing pad A>

In one or a plurality of embodiments, the base layer obtained by filling a rubber-like substance such as a non-woven fabric such as cotton or a synthetic fiber or a styrene-butadiene rubber may be used as the material of the base layer of the polishing pad A. From the viewpoint of obtaining a resin film having a small undulation and a high hardness, a polyethylene terephthalate (PET) film or a polyester film is preferable, and a PET film is more preferable. As a material of the foam layer (surface layer) of the polishing pad A, in one or more embodiments, a polyurethane elastomer, polystyrene, polyester, polyvinyl chloride, natural rubber, or the like may be mentioned. Synthetic rubber or the like is preferably a polyurethane elastomer from the viewpoint of not greatly impairing the polishing rate and reducing long-period defects. In the present specification, the "undulation" of the substrate means the unevenness of the surface of the substrate whose wavelength is larger than the roughness.

<Compression ratio of polishing pad A>

The compression ratio 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 greatly impairing the polishing rate and reducing long-term defects. It is 15.0% or less, more preferably 10.0% or less, further preferably 7.0% or less, and still more preferably 5.0% or less.

The compression ratio of the polishing pad can be measured by a compression tester based on the compression ratio measurement method described in Japanese Industrial Standards (JIS) L1096. That is, it can be obtained by subtracting the thickness of the polishing pad measured at 1000 g/cm ² from the thickness (T0) of the polishing pad measured under a standard pressure (100 g/cm ² ) ( T1), divide the difference obtained by T0 and multiply by 100. The compression ratio of the polishing pad can be controlled, for example, by the thickness of the foamed layer or the pore size of the base layer side of the foamed layer, or the material of the base layer.

<Average pore diameter of the polishing pad A>

The average pore diameter of the pore portion on the surface of the polishing pad A is preferably 10 μm or more and 100 μm or less, and more preferably 15 μm or more and 80 μm or less from the viewpoint of not greatly impairing the polishing rate and reducing long-period defects. Further, it is preferably 20 μm or more and 60 μm or less, and more preferably 25 μm or more and 55 μm or less.

The average pore diameter of the pore portion on the surface of the polishing pad can be obtained by adding a pigment such as carbon black to the raw material of the polyurethane elastomer, or a hydrophilic active agent for promoting foaming, or elasticizing the polyurethane. The wet coagulation of the body is controlled by an additive such as a hydrophobic active agent stabilized. Further, the above average pore diameter can be obtained by the following method. First, the surface of the polishing pad is observed by a scanning electron microscope (preferably 100 to 300 times), and the image is taken into a personal computer (PC). Then, the captured image is analyzed by the image analysis software in the PC, and the average pore diameter is obtained as the average diameter of the circle-equivalent diameter of the pore portion. As the image analysis software, for example, Win ROOF (Sangu Business) can be used.

<Thickness of polishing pad A>

The thickness of the polishing pad A is preferably 0.7 mm or more and 1.5 mm or less, more preferably 0.8 mm or more and 1.4 mm or less from the viewpoint of not greatly impairing the polishing rate and reducing long-period defects. It is preferably 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) Grinding load]

The so-called grinding load in the present invention means grinding of the substrate to be polished by the platen during grinding. The pressure exerted on the surface. The polishing load in the step (1) is preferably 30 kPa or less, more preferably 25 kPa or less, further preferably 20 kPa or less, and further preferably from the viewpoint of not greatly impairing the polishing rate and reducing long-cycle defects. It is preferably 18 kPa or less, more preferably 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, still more preferably 8 kPa or more, and furthermore, from the viewpoint of not greatly impairing the polishing rate and reducing long-period defects. Good for 9kPa or more. 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 further preferably 7 kPa or more and 20 kPa or less from the viewpoint of not greatly impairing the polishing rate and reducing long-term defects. Furthermore, it is more preferably 8 kPa or more and 18 kPa or less, still more preferably 9 kPa or more and 16 kPa or less, and still more preferably 9 kPa or more and 14 kPa or less. The above-mentioned polishing load can be adjusted by the air pressure or weight load on the platen or the substrate.

[Step (1) grinding amount]

Regarding the amount of polishing of each of the substrates to be polished (diameter: 95 mm) in the step (1), in one or a plurality of embodiments, it is preferable that the polishing rate is not greatly impaired and the long-period defects are reduced. It is 110 mg or more and 160 mg or less, more preferably 115 mg or more and 155 mg or less, further preferably 120 mg or more and 150 mg or less. The substrate to be polished of different diameters is set in accordance with the above range in accordance with the area thereof. In the polishing of the step (1) in the production method of the present invention, the above-mentioned polishing liquid composition I containing specific non-spherical cerium oxide particles A, spherical cerium oxide particles B, an acid, an oxidizing agent and water is used. Therefore, long-period defects can be effectively eliminated by the amount of polishing in the above range.

[Supply speed of the polishing liquid composition I in the step (1)]

The supply rate of the polishing liquid composition I in the step (1) is preferably 2.5 mL/min or less, more preferably 2.0 mL/min, per 1 cm ² of the substrate to be polished from the viewpoint of economy. Hereinafter, it is more preferably 1.5 mL/min or less, further preferably 1.0 mL/min or less, further preferably 0.5 mL/min or less, and still more preferably 0.2 mL/min or less. The supply rate is preferably 0.01 mL/min or more, more preferably 0.03 mL/min or more, and still more preferably 0.05 mL/min or more per 1 cm ² of the substrate to be polished. The viewpoint of the economical efficiency and the polishing rate is preferably 0.01 mL/min or more and 2.5 mL/min or less, and more preferably 0.03 mL/min or more per 1 cm ² of the substrate to be polished. Further, it is 2.0 mL/min or less, more preferably 0.03 mL/min or more and 1.5 mL/min or less, further preferably 0.03 mL/min or more and 1.0 mL/min or less, and more preferably 0.05 mL/min or more and 0.5 or more. It is more preferably 0.05 mL/min or more and 0.2 mL/min or less in terms of mL/min or less.

[Supply amount of the polishing liquid composition I in the step (1)]

The supply amount of the polishing liquid composition I in the step (1) depends on the supply rate of the polishing liquid composition I, and it is preferable to further reduce the supply amount from the viewpoint of economy. It is considered that in one or a plurality of embodiments of the present invention, since the polishing liquid composition I can act on the substrate more efficiently, the supply amount of the polishing liquid can be made smaller than the previous supply amount. The reduction efficiency of the supply amount of the polishing liquid in the present invention can be specifically evaluated by the method described in the examples.

[Method of supplying the polishing liquid composition I to the grinder in the step (1)]

As a method of supplying the polishing liquid composition I to a grinder, for example, a method of continuously supplying using a pump or the like can be mentioned. When the polishing liquid composition I is supplied to the grinding machine, it may be divided into a plurality of ingredients for liquid preparation in consideration of the storage stability of the polishing liquid composition I, etc., in addition to the method of supplying the liquid composition in the form of a single liquid. Supply in the form of two or more liquids. In the latter case, for example, the above-mentioned plurality of component liquids are mixed in a supply pipe or a substrate to be polished to form a polishing liquid composition I.

[Step (2): Washing step]

The step (2) is a step of washing the substrate obtained in the step (1). In the step (2), in one or more embodiments, the step of washing the substrate subjected to the step (1) coarse polishing using a detergent composition is used. The washing method in the step (2) is not particularly limited, in one or plural In one embodiment, the method of immersing the substrate obtained in the step (1) in the detergent composition (cleaning method a) and discharging the detergent composition are obtained in the step (1). A method of supplying a detergent composition on the surface of the substrate (cleaning method b).

<Washing method a>

In the cleaning method a, the impregnation conditions of the substrate in the detergent composition are not particularly limited. For example, the temperature of the detergent composition is preferably from 20 to 100 from the viewpoint of safety and workability. The immersion time is preferably from 10 seconds to 30 minutes from the viewpoint of the detergency of the detergent composition and the production efficiency. From the viewpoint of improving the removability of the residue and the dispersibility of the residue (detergency to the residue), it is preferred to apply ultrasonic vibration to the detergent composition. The frequency of the ultrasonic wave is preferably 20 kHz or more and 2000 kHz or less, more preferably 40 kHz or more and 2000 kHz or less, and still more preferably 40 kHz or more and 1500 kHz or less.

<Washing method b>

In the above-described cleaning method b, from the viewpoint of promoting the detergency of the residue or the solubility of the oil component, it is preferred to eject the detergent composition to which ultrasonic vibration is applied, and to contact the detergent composition. The surface is washed on the surface of the substrate; or the detergent composition is supplied onto the surface of the substrate to be cleaned by injection, and the surface to which the detergent composition is supplied is washed by a cleaning brush. net. Further, in the cleaning method b, it is preferable that the detergent composition to which ultrasonic vibration is applied is supplied to the surface of the object to be cleaned by injection, and the surface is supplied to the surface of the detergent composition. Wash and brush with a brush and wash.

As a method of supplying the detergent composition to the surface of the substrate to be cleaned, a known method such as a spray nozzle can be employed. The washing brush is not particularly limited, and for example, a nylon brush or a PVA (polyvinyl alcohol) sponge brush can be used. The frequency of the ultrasonic wave may be the same as the value preferably used in the above cleaning method a.

In the step (2), in addition to the cleaning method a and/or the cleaning method b, one or more may be included. A known washing step such as rinsing washing, washing with a spinner or the like, paddle washing, scrubbing washing or the like is employed.

[Step (2) detergent composition]

As the detergent composition of the step (2), in one or a plurality of embodiments, those containing an alkali agent, water, and various additives as needed may be used.

<Alkaline agent in detergent composition>

The alkali agent used in the above detergent composition may be any of an inorganic base agent and an organic base agent. Examples of the inorganic alkali agent include ammonia, potassium hydroxide, and sodium hydroxide. The organic alkali agent may, for example, be one or more selected from the group consisting of hydroxyalkylamine, tetramethylammonium hydroxide, and choline. These alkali chemicals may be used singly or in combination of two or more. From the viewpoint of improving the detergency of the detergent composition on the substrate and improving the storage stability, the alkali agent is preferably selected from the group consisting of potassium hydroxide, sodium hydroxide, monoethanolamine, and methyl group. At least one selected from the group consisting of diethanolamine and aminoethylethanolamine is more preferably at least one selected from the group consisting of potassium hydroxide and sodium hydroxide.

The content of the alkali agent in the detergent composition is preferably from the viewpoint of improving the detergency of the detergent composition on the substrate and improving the safety of the detergent composition during handling. 0.05% by mass or more and 10% by mass or less, more preferably 0.08% by mass or more and 5% by mass or less, further preferably 0.1% by mass or more and 3% by mass or less.

The pH of the detergent composition is preferably 8 or more and 14 or less, more preferably 9 or more and 13 or less, and still more preferably 10 or more, from the viewpoint of improving the detergency of the residue on the substrate. Further, it is 13 or less, and more preferably 11 or more and 13 or less. Further, the pH value of the detergent composition at 25 ° C can be measured using a pH meter, and the value of the electrode after being immersed in the detergent composition for 2 minutes.

<Various Additives in Detergent Composition>

In addition to the alkali agent, the detergent composition may also contain a nonionic surfactant, a chelate A mixture, an ether carboxylate or a fatty acid, an anionic surfactant, a water-soluble polymer, an antifoaming agent (excluding a surfactant equivalent to a component), an alcohol, a preservative, an antioxidant, and the like.

The content of the component other than water in the detergent composition is considered to be both workability, economy, and improvement in the degree of enrichment and storage stability which are sufficient to improve the storage stability. The total content of the water and the content of the components other than water is 100% by mass, preferably 10% by mass or more and 60% by mass or less, more preferably 15% by mass or more and 50% by mass or less, and still more preferably 15% by mass. The mass% or more and 40% by mass or less.

The detergent composition can be used diluted. In view of the washing efficiency, the dilution ratio is preferably 10 times or more and 500 times or less, more preferably 20 times or more and 200 times or less, and still more preferably 50 times or more and 100 times or less. The dilution water can be the same as the water in the above-mentioned slurry composition I. The detergent composition can be made into a concentrate which is premised on the above dilution ratio. Therefore, in the case of the concentrate, the content of the component other than water in the detergent composition is preferably 0.02% by mass when the total content of the water and the content of the component other than water is 100% by mass. The amount is preferably 6% by mass or less, more preferably 0.1% by mass or more and 3% by mass or less, further preferably 0.15% by mass or more and 1% by mass or less.

[Step (3): Fine grinding step]

In the step (3), in one or more embodiments, the polishing target surface of the substrate obtained in the step (2) is polished using the polishing liquid composition II containing the ceria particles C. In the other or a plurality of embodiments, the step (3) is a step of supplying the polishing liquid composition II containing the ceria particle C to the polishing target surface of the substrate obtained in the step (2) to contact the polishing pad. The polishing target surface moves at least one of the polishing pad and the substrate to be polished to polish the polishing target surface. The grinder used in the step (3) is used in the step (1) from the viewpoint of reducing the protrusion defects and the viewpoint of using a polishing pad having a different aperture and coarse grinding in order to efficiently reduce other surface defects. The grinder is different from the grinder.

The manufacturing method of the present invention can be highly efficient without causing substantial damage to the grinding speed of the coarse grinding by the coarse grinding step of the step (1), the washing step of the step (2), and the fine grinding step of the step (3). The substrate is manufactured to reduce the number of long-period defects and to reduce the number of protrusion defects after fine grinding.

[Step (3) Slurry Composition II]

The polishing liquid composition II used in the step (3) contains cerium oxide particles C as abrasive grains from the viewpoint of reducing the protrusion defects after the finish polishing. The cerium oxide particles C used are preferably colloidal cerium oxide from the viewpoint of reducing long-wavelength fluctuation after finish polishing. The polishing liquid composition II preferably contains substantially no alumina abrasive grains from the viewpoint of reducing protrusion defects after finish polishing. In one or more embodiments, the ceria particle C is spherical. The term "long-wavelength fluctuation" as used herein refers to an undulation observed at a wavelength of 500 to 5000 μm. By reducing the undulation of the surface of the substrate after grinding, the amount of floating of the magnetic head can be reduced, and the recording density of the magnetic disk substrate can be improved.

The volume average particle diameter (D1) measured by the dynamic light scattering method of the ceria particle C used in the polishing composition II is preferably 5 nm from the viewpoint of reducing the protrusion defect after the finish polishing. The above is 50 nm or less, more preferably 10 nm or more and 45 nm or less, further preferably 15 nm or more and 40 nm or less, and still more preferably 20 nm or more and 35 nm or less. The volume average particle diameter (D1) measured by the dynamic light scattering method of the ceria particle C is preferably smaller than that of the non-spherical ceria particle A in terms of reducing the protrusion defect after the fine polishing. The volume average particle diameter (D1) measured by dynamic light scattering.

The CV90 of the ceria particle C is preferably 10.0% or more, and more preferably 15.0% or more in terms of suppressing the decrease in the polishing rate and reducing the protrusion defect after the finish polishing in one or a plurality of embodiments. Further, it is preferably 20.0% or more, and from the same viewpoint, it is preferably 35.0% or less, more preferably 32.0% or less, still more preferably 30.0% or less. In one or a plurality of embodiments, the CV90 of the spherical ceria particle B is 10.0% or more and 35.0% or less, preferably 15.0% or more. 32.0% or less, more preferably 20.0% or more and 30.0% or less.

The content of the ceria particle C in the polishing liquid composition II is preferably 0.5% by mass or more and 20% by mass or less, more preferably 1.0, from the viewpoint of reducing long-wavelength fluctuations and protrusion defects after finish polishing. The mass% or more and 15 mass% or less are further preferably 3.0% by mass or more and 13% by mass or less, and more preferably 4.0% by mass or more and 10% by mass or less.

The polishing liquid composition II preferably contains one or more selected from the group consisting of a heterocyclic aromatic compound, a polyamine compound, and a polymer having an anionic group, from the viewpoint of reducing long-wavelength fluctuation and protrusion defects after finish polishing. More preferably, it contains two or more types, and further preferably contains a heterocyclic aromatic compound, a polyamine compound, and a polymer having an anionic group.

The polishing liquid composition II preferably contains an acid or an oxidizing agent from the viewpoint of increasing the polishing rate. The preferred use of the acid or the oxidizing agent is the same as in the case of the above-mentioned polishing liquid composition I. The water used in the polishing liquid composition II, the pH of the polishing liquid composition II, and the preparation method of the polishing liquid composition II are the same as those in the case of the polishing liquid composition I described above.

[Step (3) of the polishing pad]

The polishing pad used in the step (3) may be the same type of polishing pad as the polishing pad used in the step (1). The average pore diameter of the polishing pad used in the step (3) is preferably 1 μm or more and 50 μm or less, and more preferably 2 μm or more and 40 μm or less from the viewpoint of reducing long-wavelength fluctuations and protrusion defects after finish polishing. Further, it is preferably 3 μm or more and 30 μm or less.

[Step (3) grinding 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 fluctuations and protrusion defects after finish polishing. The polishing load is preferably 7.5 kPa or more, more preferably 8.5 kPa or more, from the viewpoint of reducing long-wavelength fluctuations and protrusion defects after finish polishing. Good is 9.5kPa or more. 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 9.5 kPa or more and 13 kPa or less from the viewpoint of reducing the long wavelength fluctuation and the protrusion defect after the finish polishing. .

[Step (3) grinding amount]

The polishing amount per unit area (1 cm ² ) of the substrate to be polished in the polishing time per minute in the step (3) is preferably 0.02 from the viewpoint of reducing the long wavelength fluctuation and the protrusion defect after the finish polishing. More preferably, it is 0.03 mg or more, and further preferably 0.04 mg or more. The polishing amount is preferably 0.15 mg or less, more preferably 0.12 mg or less, and still more preferably 0.10 mg or less from the viewpoint of improving productivity. 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 still more preferably 0.04 mg or more and 0.10 mg or less from the same viewpoint as described above.

The supply rate of the polishing liquid composition II in the step (3) and the method of supplying the polishing liquid composition II to the polishing machine are the same as those in the case of the polishing liquid composition I described above.

According to the manufacturing method of the present invention, in one or a plurality of embodiments, the polishing rate during the rough polishing is not greatly impaired and the long-period defects are reduced, so that a high substrate yield and excellent productivity can be exhibited. The effect of the disk substrate on which the protrusion defects are reduced is manufactured.

[grinding method]

Another aspect of the invention pertains to a method of polishing having the above steps (1), (2), and (3). The substrate to be polished, the polishing liquid composition I, the non-spherical cerium oxide particles A, the spherical cerium oxide particles B, the polishing liquid composition II, the cerium oxide particles C, and the steps in the steps (1) to (3) The polishing method and conditions, the detergent composition, and the cleaning method can be the same as those of the above-described method for manufacturing a magnetic disk substrate of the present invention.

By using the polishing method of the present invention, in one or more embodiments, the polishing rate at the time of rough grinding is not greatly impaired, and long-period defects can be reduced, thereby enabling The effect of the disk substrate on which the projection defects are reduced can be produced with a high substrate yield and excellent productivity.

In the manufacturing method and the polishing method of the present invention, in one or more embodiments, the first polishing machine for polishing (rough grinding) the substrate to be polished using the polishing liquid composition I can be provided as shown in FIG. 5 . 51. The cleaning unit 52 that cleans the substrate polished by the first polishing machine 51 and the polishing system of the magnetic disk substrate of the second polishing machine 53 that polishes the cleaned substrate using the polishing liquid composition II get on. Therefore, the present invention relates to a first polishing machine equipped with the polishing of the above step (1), a cleaning unit for performing the cleaning of the above step (2), and the polishing of the above step (3). The grinding system of the disk substrate of the second grinder. As described above, the polishing liquid composition I and the polishing liquid composition II can be used as described above with respect to the substrate to be polished, the polishing pad used in each polishing machine, the polishing method and conditions, the detergent composition, and the cleaning method. The method of manufacturing the magnetic disk substrate of the present invention described above is the same.

In one or a plurality of embodiments, the polishing system of the present invention may have a polishing amount of at least one sheet (diameter: 95 mm) of the substrate to be polished polished by the first polishing machine 51, preferably 110 mg or more and 160 mg or less. More preferably, it is a mechanism (polishing control unit) (not shown) which is confirmed to be 115 mg or more and 155 mg or less, and more preferably 120 mg or more and 150 mg or less. In one or a plurality of embodiments, the mechanism (polishing control unit) controls the first grinder 51 in accordance with the amount of polishing of the substrate. Here, an embodiment of the operation of the polishing system of the present invention (the polishing step of the method of manufacturing the disk substrate) will be described with reference to FIG. 5 with reference to FIG. First, the substrate to be polished is polished (roughly polished) by the first grinder 51 (stage S61). Then, the polishing control unit determines whether or not the amount of polishing of the substrate by the first polishing machine 51 is within a specific polishing amount range (here, 110 to 160 mg) (stage S62). When the polishing amount is within a specific polishing amount range, the rough-polished substrate is washed by the cleaning unit 52 (stage S62), and the cleaned substrate is ground by the second polishing machine 53 ( Stage S63). On the other hand, the above grinding amount is not specific In the case of the grinding amount range, the grinding of the first grinding machine 51 or the grinding is stopped (stage S65).

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

<1> A method of producing a magnetic disk substrate, comprising: (1) a step of polishing a polishing target surface of the substrate to be polished using the polishing liquid composition I; and (2) washing the substrate obtained in the step (1). a step of (3) grinding the substrate obtained in the step (2) using the polishing liquid composition II containing the ceria particle C, and performing the above steps (1) and (3) using different grinding machines, Further, (i) the polishing liquid composition I of the above step (1) contains non-spherical cerium oxide particles A, spherical cerium oxide particles B, an acid, an oxidizing agent, and water; (ii) the above step (1) In the polishing composition I, the mass ratio (A/B) of the non-spherical cerium oxide particles A to the spherical cerium oxide particles B is 80/20 or more and 99/1 or less with respect to the cerium oxide particles. The total content of the total non-spherical cerium oxide particles A and the spherical cerium oxide particles B exceeds 98.0% by mass; (iii) the ΔCV value of the above non-spherical cerium oxide particles A is more than 0.0% and less than 10% %, here, the ΔCV value is the difference between CV30 and CV90 (ΔCV=CV30-CV90), which is based on the scattering at a detection angle of 30° by dynamic light scattering method. The standard deviation of the intensity distribution is divided by the average particle diameter based on the above-described scattering intensity distribution and multiplied by 100. The CV90 is divided by the standard deviation of the scattering intensity distribution based on the detection angle of 90° by the average based on the above scattering intensity distribution. The particle diameter is multiplied by 100; (iv) the volume average particle diameter (D1) of the non-spherical cerium oxide particle A measured by dynamic light scattering method and the ratio measured by the BET method The particle diameter ratio (D1/D2) of the surface area-converted particle diameter (D2) is 2.00 or more and 4.00 or less; (v) the volume average particle diameter of the spherical cerium oxide particle B measured by dynamic light scattering method ( D1) is 6.0 nm or more and 80.0 nm or less; (vi) The above acid is selected from the group consisting of phosphoric acid, phosphonic acid, organic phosphonic acid, and combinations thereof.

<2> The production method according to <1>, wherein the non-spherical cerium oxide particle A is selected from the group consisting of a cerium oxide particle A1 of a ginkgoose type, a cerium oxide particle A2 of a heteromorphic type, and a oxidized type of a sulphate type.矽 particle A3, and a combination of these At least one.

<3> The production method according to <1> or <2>, wherein the ΔCV value of the non-spherical cerium oxide particle A is preferably more than 0.0%, more preferably 0.2% or more, still more preferably 0.3%. The above is more preferably 0.4% or more.

The production method according to any one of <1> to <3> wherein the non-spherical cerium oxide particle A preferably has a ΔCV value of less than 10.0%, more preferably 8.0% or less. It is preferably 7.0% or less, and more preferably 4.0% or less.

The manufacturing method according to any one of <1> to <4> wherein the non-spherical cerium oxide particle A preferably has a ΔCV value of more than 0.0% and less than 10.0%, more preferably 0.2. % or more and 8.0% or less, further preferably 0.3% or more and 7.0% or less, and still more preferably 0.4% or more and 4.0% or less.

The production method according to any one of <1> to <5> wherein the volume average particle diameter (D1) of the non-spherical cerium oxide particles A is preferably 120.0 nm or more, more preferably 150.0 nm. The above is more preferably 160.0 nm or more, still more preferably 170.0 nm or more, still more preferably 180.0 nm or more, still more preferably 190.0 nm or more, and still more preferably 200.0 nm or more.

The production method according to any one of <1> to <6> wherein the volume average particle diameter (D1) of the non-spherical cerium oxide particles A is preferably less than 300.0 nm, more preferably not It is 260.0 nm, more preferably less than 250.0 nm, still more preferably less than 220.0 nm, and even more preferably less than 210.0 nm.

The production method according to any one of <1> to <7> wherein the volume average particle diameter (D1) of the non-spherical cerium oxide particles A is preferably 120.0 nm or more and less than 300.0 nm. More preferably, it is 120.0 nm or more and less than 260.0 nm, further preferably 150.0 nm or more and less than 260.0 nm, more preferably 160.0 nm or more and less than 260.0 nm, more preferably 170.0 nm or more and less than 260.0 nm. More preferably, it is 180.0 nm or more and less than 250.0 nm, more preferably 190.0 nm or more and less than 220.0 nm, and further Preferably, it is 200.0 nm or more and less than 210.0 nm.

The production method according to any one of <1> to <8> wherein the volume average particle diameter (D1) and the borrowed by the dynamic light scattering method of the non-spherical cerium oxide particle A are The particle diameter ratio (D1/D2) of the specific surface area converted particle diameter (D2) measured by the BET method is preferably 2.00 or more, more preferably 2.50 or more, still more preferably 3.00 or more, still more preferably 3.50 or more.

The production method according to any one of <1> to <9> wherein the volume average particle diameter (D1) and the bulk of the non-spherical cerium oxide particle A measured by a dynamic light scattering method are used. The particle diameter ratio (D1/D2) of the specific surface area converted particle diameter (D2) measured by the BET method is preferably 4.00 or less, more preferably 3.90 or less, still more preferably 3.80 or less.

The production method according to any one of <1> to <10> wherein the volume average particle diameter (D1) and the bulk of the non-spherical cerium oxide particle A measured by a dynamic light scattering method are used. The particle diameter ratio (D1/D2) of the specific surface area converted particle diameter (D2) measured by the BET method is preferably 2.00 or more and 4.00 or less, more preferably 2.50 or more and 3.90 or less, still more preferably 3.0 or more. Further, it is 3.90 or less, and more preferably 3.50 or more and 3.80 or less.

The production method according to any one of <1> to <11>, wherein the non-spherical cerium oxide particle A has a CV90 of preferably 20.0% or more, more preferably 25.0% or more, and still more preferably 27.0% or more.

The production method according to any one of <1> to <12> wherein the non-spherical cerium oxide particle A has a CV90 of preferably 40.0% or less, more preferably 38.0% or less, further preferably 35.0% or less, and more preferably 32.0% or less.

The production method according to any one of <1> to <13>, wherein the CV90 of the non-spherical cerium oxide particle A is preferably 20.0% or more and 40.0% or less, more preferably 25.0% or more. It is 38.0% or less, more preferably 25.0 or more and 35.0% or less, and still more preferably 27.0% or more and 32.0% or less.

<15> The manufacturing method according to any one of <1> to <14> wherein The content of the non-spherical cerium oxide particles A in the abrasive composition I 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 still more preferably 2% by mass or more. .

The production method according to any one of the above aspects, wherein the content of the non-spherical cerium oxide particles A in the polishing liquid composition I is preferably 30% by mass or less, more preferably 25 mass% or less, more preferably 20 mass% or less, still more preferably 15 mass% or less.

The production method according to any one of the above aspects, wherein the content of the non-spherical cerium oxide particles A in the polishing liquid composition I is preferably 0.1% by mass or more and 30% by mass. The amount is preferably 0.5% by mass or more and 25% by mass or less, more preferably 1% by mass or more and 20% by mass or less, and still more preferably 2% by mass or more and 15% by mass or less.

The production method according to any one of <1> to <17> wherein the non-spherical cerium oxide particles A are cerium oxide particles produced by a particle growth method using water glass as a raw material.

The manufacturing method according to any one of <1> to <18> wherein the spherical ceria particle B preferably has a ΔCV value of more than 0.0%, more preferably 0.2% or more, and further preferably It is 0.3% or more, and more preferably 0.4% or more.

The manufacturing method according to any one of <1> to <19> wherein the spherical ceria particle B preferably has a ΔCV value of less than 10.0%, more preferably 8.0% or less, and further Preferably, it is 7.0% or less, and more preferably 4.0% or less.

The manufacturing method according to any one of <1> to <20> wherein the spherical ceria particle B preferably has a ΔCV value of more than 0.0% and less than 10.0%, more preferably 0.2%. The above is 8.0% or less, more preferably 0.3% or more and 7.0% or less, and still more preferably 0.4% or more and 4.0% or less.

The manufacturing method according to any one of <1> to <21> wherein the above-mentioned ball The volume average particle diameter (D1) of the cerium oxide particle B is preferably 6.0 nm or more, more preferably 7.0 nm or more.

The production method according to any one of <1> to <22> wherein the volume average particle diameter (D1) of the spherical cerium oxide particles B is preferably 80.0 nm or less, more preferably 70.0 nm or less. Further, it is preferably 60.0 nm or less.

The production method according to any one of <1> to <23>, wherein the volume average particle diameter (D1) of the spherical cerium oxide particles B is preferably 6.0 nm or more and 80.0 nm or less, more preferably It is 6.0 nm or more and 70.0 nm or less, More preferably, it is 7.0 nm or more and 60.0 nm or less.

The method according to any one of the aspects of the present invention, wherein the spherical cerium oxide particles B are two kinds of particles having different particle diameters, and the two kinds of particles are 6.0 nm or more and 15.0 nm or less. The combination of the spherical particles and the spherical particles of 15.5 nm or more and 70.0 nm or less, or the combination of the spherical particles of 15.5 nm or more and 30.0 nm or less and the spherical particles of 30.5 nm or more and 70.0 nm or less.

The manufacturing method according to any one of <1> to <25> wherein the volume average particle diameter (D1) of the spherical cerium oxide particle B measured by a dynamic light scattering method is used The particle diameter ratio (D1/D2) of the specific surface area converted particle diameter (D2) measured by the BET method is preferably 1.00 or more, more preferably 1.10 or more, still more preferably 1.15 or more.

The manufacturing method according to any one of <1> to <26> wherein the volume average particle diameter (D1) of the spherical cerium oxide particle B measured by a dynamic light scattering method is used The particle diameter ratio (D1/D2) of the specific surface area converted particle diameter (D2) measured by the BET method is preferably 1.50 or less, more preferably 1.40 or less, still more preferably 1.30 or less.

The manufacturing method according to any one of <1> to <27> wherein the volume average particle diameter (D1) of the spherical cerium oxide particle B measured by dynamic light scattering method is used The particle diameter ratio (D1/D2) of the specific surface area converted particle diameter (D2) measured by the BET method is preferably 1.00 or more and 1.50 or less, preferably 1.10 or more and 1.40 or less, more preferably 1.15 or more. 1.30 or less.

The production method according to any one of <1> to <28> wherein the spherical ceria particle B has a CV90 of preferably 10.0% or more, more preferably 15.0% or more, still more preferably 20.0. %the above.

The production method according to any one of <1> to <29> wherein the spherical ceria particle B has a CV90 of preferably 35.0% or less, more preferably 32.0% or less, still more preferably 30.0. %the following.

The production method according to any one of <1> to <30> wherein the spherical ceria particle B has a CV90 of preferably 10.0% or more and 35.0% or less, more preferably 15.0% or more and 32.0. % or less is further preferably 20.0% or more and 30.0% or less.

The production method according to any one of the above aspects, wherein the content of the spherical cerium oxide particles B in the polishing liquid composition I is preferably 0.01% by mass or more, more preferably 0.05%. The mass% or more is more preferably 0.1% by mass or more, and still more preferably 0.2% by mass or more.

The production method according to any one of the above aspects, wherein the content of the spherical cerium oxide particles B in the polishing liquid composition I is preferably 3% by mass or less, more preferably 2.5 or less. The mass% or less is more preferably 2% by mass or less, and still more preferably 1.5% by mass or less.

The production method according to any one of <1> to <33> wherein a volume particle size distribution of the non-spherical cerium oxide particles A and the spherical cerium oxide particles B in the polishing liquid composition I The total of the overlapping frequencies is preferably 0% or more and 50% or less, more preferably 10% or more and 45% or less, further preferably 15% or more and 40% or less, and still more preferably 20% or more and 35% or less. .

The production method according to any one of <1> to <34> wherein the mass ratio of the non-spherical cerium oxide particles A to the spherical cerium oxide particles B in the polishing liquid composition I (A/B) is preferably 80/20 or more, more preferably 85/15 or more, and further preferably 90/10 or more.

The manufacturing method according to any one of <1> to <35> wherein the mass ratio of the non-spherical cerium oxide particles A to the spherical cerium oxide particles B in the polishing liquid composition I (A/B) is preferably 99/1 or less, more preferably 95/5 or less, still more preferably 92/8 or less.

The production method according to any one of <1> to <36> wherein the non-spherical cerium oxide particles A and spherical oxidized particles in the polishing liquid composition I with respect to the entire cerium oxide particles. The total content of the cerium particles B is preferably more than 98.0% by mass, more preferably 98.5% by mass or more, still more preferably 99.0% by mass or more, still more preferably 99.5% by mass or more, and still more preferably 99.8% by mass or more. More preferably, it is substantially 100% by mass.

The production method according to any one of the above aspects, wherein the content of the acid in the polishing liquid composition I is preferably 0.001% by mass or more and 5% by mass or less, more preferably 0.01% by weight. The mass% or more and 4 mass% or less are further preferably 0.05% by mass or more and 3% by mass or less, and more preferably 0.1% by mass or more and 2.5% by mass or less.

The manufacturing method of any one of <1> to <38>, wherein the polishing liquid composition I contains substantially no alumina particles.

The production method according to any one of the above-mentioned items, wherein the pH of the polishing liquid composition I is preferably 0.5 or more and 6.0 or less, more preferably 0.7 or more and 4.0 or less, and further It is preferably 0.9 or more and 3.0 or less, more preferably 1.0 or more and 3.0 or less, still more preferably 1.2 or more and 2.5 or less, and still more preferably 1.4 or more and 2.0 or less.

The production method according to any one of <1> to <40> wherein the polishing liquid composition I is polished to a Ni-P-plated aluminum alloy substrate.

The method of any one of the above-mentioned steps (1), wherein the polishing amount of each of the substrates to be polished (having a diameter of 95 mm) is preferably 110 mg or more and 160 mg or less. It is preferably 115 mg or more and 155 mg or less, and more preferably 120 mg or more and 150 mg or less.

<43> A method of polishing a disk substrate, comprising the steps (1) to (3) in the method of manufacturing a disk substrate according to any one of <1> to <42>.

<44> A polishing system for a disk substrate, comprising: a first polishing machine that performs the polishing of the step (1) in the method for manufacturing a disk substrate according to any one of <1> to <42>; The cleaning unit of the step (2) in the method for producing a magnetic disk substrate according to any one of the above aspects, wherein the magnetic device according to any one of <1> to <42> is subjected to the magnetic cleaning according to any one of <1> to <42>. A second grinding machine that is ground in the step (3) in the method of manufacturing the dish substrate.

Example

The invention is illustrated in more detail by the following examples, but these are merely illustrative, and the invention is not limited by the examples.

The polishing liquid composition I used in the step (1) and the polishing liquid composition II used in the step (3) are prepared as follows, and the substrate to be polished containing the following conditions of the steps (1) to (3) is performed. Grinding. 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 the polishing liquid composition I used in the step (1) (rough grinding)]

The non-spherical cerium oxide abrasive particles A and spherical cerium oxide particles B (both colloidal cerium oxide particles) of Table 1, the acid of Table 2, hydrogen peroxide, and water were used, and the preparation step (1) was used. The polishing liquid composition I (Examples 1 to 16, Reference Examples 1 to 9, and Comparative Examples 1 to 6) (Table 2). The content of each component in the polishing liquid composition I was set to colloidal cerium oxide particles: 6.0% by mass, acid: 1.0 to 2.4% by mass, and hydrogen peroxide: 1.0% by mass. The pH of the slurry composition I is 1.2 to 1.9. The colloidal cerium oxide particles of the cerium oxide abrasive grains of Table 1 were produced by a water glass method. The pH was measured using a pH meter (manufactured by DKK Corporation of East Asia). The value after immersing the electrode in the polishing liquid composition for 2 minutes (the same applies hereinafter).

In one or more embodiments, the type of non-spherical cerium oxide abrasive particles A of Table 1 can be based on observation images of a transmission electron microscope (TEM) and analysis thereof. Discriminant classification.

The "heterotypical cerium oxide particles" mean non-spherical cerium oxide particles having a shape in which two or more particles are aggregated or fused. In one or a plurality of embodiments, the heteromorphic cerium oxide particles are particles in a shape in which two or more particles having a particle diameter of 1.5 or more are aggregated or fused.

The "golden saccharide cerium oxide particles" refers to non-spherical cerium oxide particles having specific ridges on the surface of spherical particles. In one or a plurality of embodiments, the glyphosic cerium oxide particles are particles in a shape in which two or more particles having a particle diameter differing by 5 or more are aggregated or fused.

An electron microscope (TEM) observation photograph of the shaped colloidal cerium oxide abrasive grains is exemplified in Fig. 1, and an electron microscope (TEM) observation photograph of the gold-glycosaccharide colloidal cerium oxide abrasive grains is exemplified in Fig. 2 .

The "spherical cerium oxide particles" of the spherical cerium oxide abrasive grains B of Table 1 are spherical particles (commonly commercially available colloidal cerium oxide) which are approximately spherical.

Furthermore, the particle size of the cerium oxide particles is taken as the longest diameter of the equivalent circle measured in one particle in an electron microscope (TEM) observation image, that is, the length of the equivalent circle having the same area as the projected area of the particle. The particle size obtained.

[Preparation of the polishing liquid composition II used in the step (3) (fine polishing)]

The slurry composition II was prepared using the colloidal cerium oxide particles (abrasive particles f) of Table 1, sulfuric acid, hydrogen peroxide, and water. The content of each component in the polishing liquid composition II was set to colloidal cerium oxide particles: 5.0% by mass, sulfuric acid: 0.5% by mass, and hydrogen peroxide: 0.5% by mass. The pH of the slurry composition II was 1.4. The polishing liquid composition II was used in the step (3) in the polishing of Examples 1 to 16, Reference Examples 1 to 9, and Comparative Examples 1 to 6.

2. Determination method of each parameter

[Volume average particle size (D1) and CV90 of abrasive grains a~k measured by dynamic light scattering method]

A polishing sample, sulfuric acid, and hydrogen peroxide were added to ion-exchanged water, and the mixture was mixed to prepare a standard sample. Abrasive particles, sulfuric acid, hydrogen peroxide in standard samples The content is 0.1 to 5.0% by mass, 0.2 to 0.4% by mass, and 0.2 to 0.4% by mass, respectively, and is appropriately adjusted depending on the type of the ceria abrasive grains to be used. The standard sample was obtained by the Marquardt method at a detection angle of 90° by a dynamic light scattering device DLS-6500 manufactured by Otsuka Electronics Co., Ltd. according to the instructions attached to the manufacturer. The particle size at which the scattering intensity distribution area becomes 50% of the whole is the volume average particle diameter (D1) of the cerium oxide particles. The CV value (CV90) of the cerium oxide particles at a detection angle of 90° is calculated as a value obtained by dividing the standard deviation in the scattering intensity distribution measured by the above-described measurement method by the volume average particle diameter and multiplying by 100. .

[△CV value]

In the same manner as the measurement method of CV90 described above, the CV value (CV30) of the cerium oxide particles at a detection angle of 30° was measured, and the value obtained by subtracting CV90 from CV30 was determined as ΔCV of cerium oxide particles A or B. value.

(Measurement conditions of DLS-6500)

Detection angle 90°

Sampling time: Appropriate adjustment within 2~10(μm)

Correlation Channel: Adjusted within 256~512(ch)

Correlation Method: TI

Sampling temprature: 25.0 ° C

Detection angle 30°

Sampling timing: adjust properly within 4~20(μm)

Related channel: Adjust properly within 512~2048(ch)

Related methods: TI

Sampling temperature: 25 ° C

[Measurement of Specific Surface Area Conversion Particle Size (D2) Measured by BET Method of Abrasive Particles a~k]

Regarding the specific surface area of the abrasive particles, after the following [pretreatment], accurate weighing is accurate A measurement sample of about 0.1 g in 4 positions after the decimal point was placed in a measuring cell, and dried in an environment of 110 ° C for 30 minutes immediately before the measurement of the specific surface area, and then a specific surface area measuring device (Micromeritics automatic specific surface area measuring device "Flowsorb" was used. III 2305" (manufactured by Shimadzu Corporation) was measured by a nitrogen adsorption method (BET method).

[pretreatment]

(a) The pH of the slurry-like abrasive grains was adjusted to 2.5 ± 0.1 using an aqueous solution of nitric acid.

(b) The slurry-like abrasive grains whose pH value was adjusted to 2.5 ± 0.1 were taken into a petri dish and dried in a hot air dryer at 150 ° C for 1 hour.

(c) The sample obtained after drying was pulverized into chips in an agate mortar.

(d) The pulverized sample was suspended in ion-exchange water at 40 ° C, and filtered using a 1 μm membrane filter.

(e) The filter on the filter was thoroughly washed with 20 g of ion-exchanged water (40 ° C).

(f) The filter to which the filtrate was attached was dried at 110 ° C for 4 hours.

(g) The dried filter is taken out, taking care not to mix the filter chips therein, and pulverizing into chips in the mortar to obtain a measurement sample.

[D10, D50 and D90 of cerium oxide abrasive grains]

The cerium oxide abrasive grains were diluted with ion-exchanged water, and the obtained 1% by mass of the dispersion liquid was placed in a measuring apparatus to obtain a volume particle size distribution of the cerium oxide abrasive grains.

Measuring machine: Malvern Zetasizer Nano "Nano S"

Measurement conditions: sample amount 1.5mL

: Laser He-Ne, 3.0mW, 633nm

: The scattered light detection angle is 173°.

Then, when the cumulative volume frequency of the obtained volume particle size distribution becomes 10%, 50%, and 90%, the particle diameters are D10, D50 (volume average particle diameter) and D90, respectively.

[Total of the overlapping frequency of the particle size distribution of the cerium oxide particles]

The same measurement as the measurement of D10, D50 and D90 of cerium oxide abrasive grains By the method, the volume particle size distribution of each of the cerium oxide particle components (abrasive grains a to k) is obtained. The total cumulative volume frequency of the particle size ranges overlapped in the combination of the abrasive grains used in Examples 1 to 16 and Reference Examples 3 to 9 (Table 2) divided by the cumulative volume frequency of the entire cerium oxide particle component ( In the case of a mixture of two components, it is 200, and when it is a mixture of three components, it is 300) and is multiplied by 100, and the obtained value is calculated as the overlap frequency [%]. An example of a graph obtained by superimposing the volume particle size distribution of the combination of the abrasive grains in Examples 8 to 11 is shown in Fig. 3 .

[The shape of cerium oxide abrasive grains]

The photograph of the cerium oxide abrasive grain observed under a transmission electron microscope (TEM) (trade name "JEM-2000FX", 80 kV, 10,000 to 50,000 times) manufactured by Nippon Electronics Co., Ltd. in the form of image data using a scanner Take in the computer and use the analysis software "WinROOF (Ver.3.6)" (seller: Mitani Corporation) to observe the shape of 1000~2000 cerium oxide particles.

[Measurement of average secondary particle size of abrasive grains]

An aqueous solution containing 0.5% by mass of Poiz 530 (manufactured by Kao Corporation) was placed in a measuring apparatus as a dispersion medium, and then a sample was introduced so that the transmittance was 75 to 95%, and then ultrasonic waves were applied for 5 minutes. Thereafter, the average secondary particle diameter of the abrasive grains was measured.

Measuring machine: Laser diffraction/scattering particle size distribution measuring device LA920 manufactured by Horiba, Ltd.

Cycle strength: 4

Ultrasonic intensity: 4

3. Grinding conditions

Grinding of the substrate to be polished is performed according to steps (1) to (3). The conditions of each step are shown below. Step (3) is carried out using another mill separate from the grinder used in the step (1).

[ground substrate to be polished]

As the substrate to be polished, an aluminum alloy substrate plated with Ni-P is used. The thickness of the substrate to be polished is 1.27mm, diameter is 95mm.

[Step (1): Rough grinding]

Grinder: double-side grinder (9B double-sided grinder, manufactured by SpeedFam)

Grinding liquid: polishing liquid composition I

Abrasive pad: suede type (foaming layer: polyurethane elastomer), thickness 0.82~1.26mm, average pore diameter 20~30μm, surface layer compression ratio: 2.5% (Filwel, manufactured by Fujibo)

Platen speed: 35rpm

Grinding load: 9.8 kPa (set value)

Supply of slurry: 100mL/min (0.076mL/(cm ² .min))

Grinding time: 5 minutes

Grinding amount: 110mg or more and 160mg or less (each disc with a diameter of 95mm)

Number of substrates to be put into: 10 pieces

[Step (2): Washing]

The substrate obtained in the step (1) was washed under the following conditions.

1. The substrate obtained in the step (1) was immersed in a tank containing an alkaline detergent composition having a pH of 12 containing 0.1% by mass of a KOH aqueous solution for 5 minutes.

2. The impregnated substrate was rinsed with ion-exchanged water for 20 seconds.

3. The washed substrate is transferred to a scrubbing unit equipped with a cleaning brush and washed.

[Step (3): Fine grinding]

Grinder: double-side grinder (9B double-sided grinder, manufactured by SpeedFam), another grinder separate from the grinder used in step (1)

Grinding Fluid: Grinding Liquid Composition II

Abrasive pad: suede type (foamed layer: polyurethane elastomer), thickness 0.9 mm, average pore diameter 5 μm, surface layer compression ratio: 10.2% (manufactured by Fujibo Co., Ltd.)

Platen speed: 40rpm

Grinding load: 9.8kPa

Supply of slurry: 100mL/min (0.076mL/(cm ² .min))

Grinding time: 2 minutes

Grinding amount: 0.04~0.10mg/(cm ² .min)

Number of substrates to be put into: 10 pieces

After step (3), it is washed. The washing conditions are the same as those in the above step (2).

4. Evaluation method

[Measurement method and evaluation of grinding speed and grinding amount in step (1)]

The weight of each substrate before and after the polishing was measured using a meter ("BP-210S" manufactured by Sartorius Co., Ltd.), and introduced into the following formula to determine the amount of polishing, and the relative polishing rate of Comparative Example 1 was calculated as 100. value. The results are shown in Table 2.

Weight loss (g) = {weight before grinding (g) - weight after grinding (g)}

Grinding amount (μm) = weight loss (g) / substrate single-sided area (mm ² ) / 2 / Ni-P plating density (g / cm ³ ) × 10 ⁶

(The substrate has a single-sided area of 6597 mm ² and the Ni-P plating density is 8.4 g/cm ³ and is calculated)

[Evaluation method of long period defects (PED) on the surface of the substrate after step (1)]

The both sides (total 20 points) of the 10 sheets after the polishing in the step (1) were measured under the following conditions, and the incidence (%) was determined. As shown in Fig. 4, the small spot which was confirmed on the surface of the substrate was PED, and it was visually confirmed on the surface of the substrate that even one PED point was considered to have a long-period defect on the surface.

Long-period defect occurrence rate (%) = (number of substrate faces where long-period defects occur / 20) × 100

The long-term defect occurrence rate was evaluated in five levels according to the following criteria. That is, a larger value means that the incidence of long-period defects is lower. The results are shown in Table 2.

[Evaluation Benchmark]

Long-term defect incidence: assessment

10% or less: 5 "Maximum suppression occurs, and substrate yield can be expected to increase"

More than 10% and less than 20%: 4 "can be used for actual production"

More than 20% and less than 30%: 3 "The actual production needs improvement"

More than 30% and less than 50%: 2 "Substrate yield dropped significantly"

More than 50%: 1 "It is far from actual production (the same level as when using ordinary cerium oxide abrasive grains)"

[measuring machine]

Optical interference type surface shape measuring machine: OptiFLAT III (KLA Tencor)

Radius Inside/Out: 14.87mm/47.83mm

Center X/Y (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 Reduction Efficiency of Supply of Grinding Fluid in Step (1)]

The polishing in the step (1) is carried out at a supply amount of the polishing liquid of 100 mL/min (0.076 mL/(cm ² .min)), and whether the decrease in the polishing rate is reduced when the supply amount of the polishing liquid is reduced under the following conditions Suppress within 10% to verify. In other words, when the decrease in the polishing rate is suppressed to within 10%, it can be considered that the reduction in the supply amount of the polishing liquid in the case where the productivity is not greatly impaired is considered to be excellent from the viewpoint of economy.

The decrease in the polishing rate (%) = (the polishing rate under the condition that the amount of the polishing liquid is reduced) / (the polishing liquid supply amount is set to the polishing rate at 100 mL/min) × 100

The reduction efficiency of the slurry supply amount is evaluated in four levels according to the following criteria, and the result will be Shown in Table 2.

[Evaluation Benchmark]

Reduction efficiency of the supply of the slurry (relative value): evaluation

Can be reduced by 30% (with a reduction in polishing rate of less than 10% at 70mL/min): A "Excellent economy"

Can be reduced by 20% (with a reduction in grinding rate of less than 10% at 80mL/min): B "Excellent economy"

Can be reduced by 10% (with a reduction in polishing rate of less than 10% at 90mL/min): C "slightly superior economy"

Can not reduce 10% (90mL / min, the grinding speed is reduced by more than 10%): D "It is difficult to reduce the amount of slurry supply in actual production"

[Evaluation method of protrusion defects after step (3)]

Measuring machine: OSA7100 (manufactured by KLA Tencor)

Evaluation: Polishing was carried out using the polishing liquid composition II, and then four sheets were randomly selected, and each of the substrates was irradiated with a laser at 10,000 rpm to measure the number of abrasive grain puncturing. The total number of abrasive burrs present on each of the two surfaces of the four substrates was divided by 8, and the number of abrasive burrs (the number of protrusion defects) on the average surface of each substrate was calculated (the comparative example 1 was set) Is a relative value of 100). The relative values of the number of protrusion defects and the results of evaluating the number of protrusion defects based on the following criteria are shown in Table 2.

[Evaluation Benchmark]

Number of protrusion defects (relative value): evaluation

Less than 95:A "The occurrence of maximum suppression is expected, and the substrate yield can be expected to increase."

95 or more and less than 110: B "can be used for actual production"

110 or more and less than 125:C "The actual production needs improvement"

125 or more: D "Substrate yield dropped significantly"

5. Results

As shown in Table 2, in Examples 1 to 16, compared with Comparative Examples 1 to 6 and Reference Examples 1 to 9, the polishing rate of the rough grinding in the step (1) was not greatly impaired, and The number of protrusion defects of the substrate after the fine polishing in the step (3) is increased, and the long period defect (PED) after the rough polishing in the step (1) can be reduced.

Further, as shown in Table 2, in Examples 1 to 16, the amount of the polishing liquid supplied in the step (1) can be further reduced as compared with the comparative examples 1 to 6 and the reference examples 1 to 9.

Industrial availability

According to the present invention, in one or more embodiments, the polishing rate can be maintained and long-period defects can be reduced, so that the substrate yield can be improved while maintaining the productivity of the disk substrate manufacturing. The invention is preferably used in the manufacture of a disk substrate in one or more embodiments.

Claims (14)

A method for producing a magnetic disk substrate, comprising: (1) a step of polishing a polishing target surface of the substrate to be polished using the polishing liquid composition I; (2) a step of washing the substrate obtained in the step (1), And (3) the step of grinding the substrate obtained in the step (2) using the polishing liquid composition II containing the ceria particle C, and performing the above steps (1) and (3) using different grinders, and i) The polishing liquid composition I of the above step (1) contains non-spherical cerium oxide particles A, spherical cerium oxide particles B, an acid, an oxidizing agent and water, and (ii) the above-mentioned polishing liquid of the above step (1) In the composition I, the mass ratio (A/B) of the non-spherical cerium oxide particles A to the spherical cerium oxide particles B is 80/20 or more and 99/1 or less, and is relative to the entire cerium oxide particles. The total content of the non-spherical cerium oxide particles A and the spherical cerium oxide particles B exceeds 98.0% by mass, and (iii) the ΔCV value of the non-spherical cerium oxide particles A is more than 0.0% and less than 10%. (iv) the volume average particle diameter (D1) of the above non-spherical cerium oxide particle A as measured by dynamic light scattering method and measured by the BET method The particle diameter ratio (D1/D2) of the surface area-converted particle diameter (D2) is 2.00 or more and 4.00 or less, and (v) the volume average particle diameter of the spherical cerium oxide particle B measured by dynamic light scattering method ( D1) is 6.0 nm or more and 80.0 nm or less, and (vi) the acid is selected from at least one selected from the group consisting of phosphoric acid, phosphonic acid, organic phosphonic acid, and combinations thereof. The method for producing a magnetic disk substrate according to claim 1, wherein the non-spherical cerium oxide particle A is selected from the group consisting of a cerium oxide particle A1 of a ginkgoose type and a cerium oxide particle of a specific type. At least one of the group A2, the bismuth dioxide particle A3 of the heteromorphic and ginkgo type, and the combination of the combinations. The method for producing a magnetic disk substrate according to claim 1, wherein the non-spherical cerium oxide particle A has a CV90 of 20.0% or more and 40.0% or less. The method of producing a magnetic disk substrate according to claim 1, wherein the spherical ceria particle B has a ΔCV value of more than 0% and 10% or less, and a CV90 of 10.0% or more and 35.0% or less. The method of manufacturing a magnetic disk substrate according to claim 1, wherein the polishing amount of each of the substrates to be polished in the step (1) is 110 mg or more and 160 mg or less. The method of producing a magnetic disk substrate according to claim 1, wherein the polishing liquid composition I is substantially free of alumina abrasive grains. The method for producing a magnetic disk substrate according to claim 1, wherein the non-spherical cerium oxide particles A are cerium oxide particles produced by a water glass method. The method for producing a magnetic disk substrate according to claim 1, wherein the spherical cerium oxide particles B are two kinds of particles having different particle diameters, and the two kinds of particles are spherical particles of 6.0 nm or more and 15.0 nm or less and 15.5 nm or more. Further, a combination of spherical particles of 70.0 nm or less, or spherical particles of 15.5 nm or more and 30.0 nm or less, and spherical particles of 30.5 nm or more and 70.0 nm or less are combined. The method for producing a magnetic disk substrate according to claim 1, wherein the total frequency of overlapping of the volume particle size distribution of the non-spherical cerium oxide particles A and the spherical cerium oxide particles B in the polishing liquid composition I is 0%. Above and below 50%. The method for producing a magnetic disk substrate according to claim 1, wherein the polishing liquid composition I has a pH of 0.5 or more and 6.0 or less. The method of manufacturing a magnetic disk substrate according to claim 1, wherein the substrate to be polished is an aluminum alloy substrate plated with Ni-P. A method of polishing a disk substrate, comprising the steps (1) to (3) in the method of manufacturing a disk substrate according to any one of claims 1 to 11. A polishing system for a disk substrate, comprising: a first grinding machine that performs the grinding of the step (1) in the method of manufacturing the magnetic disk substrate according to any one of claims 1 to 11, as claimed in claims 1 to 11 The cleaning unit of the cleaning of the step (2) in the method of manufacturing the magnetic disk substrate, and the step (3) of the method for manufacturing the magnetic disk substrate according to any one of claims 1 to 11 Grinding the second grinder. A polishing liquid composition for a magnetic disk substrate, comprising: abrasive grains, an acid, an oxidizing agent, and water, wherein the abrasive grains include non-spherical cerium oxide particles A and spherical cerium oxide particles B, and the non-spherical cerium oxide The mass ratio A/B of the particles A to the spherical cerium oxide particles B is 80/20 or more and 99/1 or less, and the ΔCV value of the non-spherical cerium oxide particles A is more than 0.0% and less than 10%. The CV90 of the non-spherical cerium oxide particles A is 20.0% or more and 40.0% or less, and the ΔCV value of the spherical cerium oxide particles B is more than 0% and 10% or less, and the spherical cerium oxide particles are contained. The CV90 of B is 10.0% or more and 35.0% or less, and the volume average particle diameter (D1) of the non-spherical cerium oxide particle A measured by dynamic light scattering method and the specific surface area measured by the BET method The particle diameter ratio (D1/D2) of the converted particle diameter (D2) is 2.00 or more and 4.00 or less, and the volume average particle diameter D1 of the spherical cerium oxide particle B measured by a dynamic light scattering method is 6.0 nm or more. And 80.0 nm or less, the acid is selected from at least one selected from the group consisting of phosphoric acid, phosphonic acid, organic phosphonic acid, and combinations thereof.