JP2014029753A - Method for producing magnetic disk substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a magnetic disk substrate, the method enabling reduction of alumina particulate sticking and other surface defects (such as residual polishing particulates, scratch, protrusion and pit).SOLUTION: A magnetic disk substrate production method includes the steps of: (1) polishing a polishing target surface of a polish object substrate, with a polishing liquid composition A containing alumina particulates and water; (2) rinsing the substrate obtained in step 1; (3) polishing a polishing target surface of the substrate obtained in step 2, with a polishing liquid composition B containing silica particulates and water; (4) cleaning the substrate obtained in step 3; and (5) polishing the substrate obtained in step (4), with a polishing liquid composition C containing colloidal silica particulates having an average primary particle diameter of 5-100 nm, inorganic acid or its salt, an organic phosphonic acid chelator and water. Further, the steps 1 through 3 are performed on the same polishing machine; and the step 5 is performed on another polishing machine different from the polishing machine.

Description

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

  In recent years, magnetic disk drives have been reduced in size and capacity, and high recording density has been demanded. In order to increase the recording density, it is necessary to reduce the unit recording area and improve the detection sensitivity of the weakened magnetic signal. Therefore, technological development for lowering the flying height of the magnetic head has been advanced. ing. The magnetic disk substrate is designed to improve the smoothness and flatness (reduction of surface roughness, waviness and edge sag) and to reduce surface defects (residual abrasive grains and scratches) in order to reduce the flying height of the magnetic head and ensure the recording area. , Reduction of protrusions, pits, etc.) is strictly demanded.

  From the viewpoint of achieving both improvement in surface quality and productivity, such as smoother and less scratches, such a requirement, the hard disk substrate manufacturing method includes a multi-stage polishing method having two or more polishing steps. Often employed (for example, Patent Documents 1 to 4). In general, in the final polishing step of the multi-stage polishing method, that is, the final polishing step, a polishing composition for finishing that contains colloidal silica particles in order to satisfy the requirements of reducing surface roughness and scratches such as scratches, protrusions, and pits. In the polishing step (also referred to as a rough polishing step) prior to the final polishing step, a polishing liquid composition containing alumina particles is used from the viewpoint of improving the polishing rate and improving the productivity.

  When alumina particles are used as abrasive grains, media scratches may be caused by texture scratches caused by the piercing of alumina particles to the substrate. In order to solve such a problem, a substrate with a predetermined polishing load using a polishing liquid composition containing aluminum oxide particles (alumina particles) having an average secondary particle diameter of 0.1 to 0.7 μm and an acid. Of a magnetic disk substrate having a rough polishing step of polishing a substrate and a final polishing step of polishing the substrate obtained in the rough polishing step with a predetermined polishing amount using a polishing composition containing colloidal particles A method has been proposed (for example, Patent Document 5).

  Recently, as a technique for further reducing the sticking of alumina particles to a substrate, a polishing liquid composition including alumina particles having a specific particle size and silica particles having a specific particle size distribution has been proposed (for example, Patent Document 6). .

  On the other hand, as a technology to reduce scratches and surface roughness in the final polishing process, it contains an anionic surfactant with a specific structure and a water-soluble polymer having an anionic group, and after polishing without impairing productivity. A polishing composition for a magnetic disk substrate that can reduce the scratch and surface roughness of the substrate has been proposed (for example, Patent Documents 7 and 8).

  Further, Patent Document 9 discloses a polishing method in which two types of abrasives are sequentially used in the same polishing machine for the purpose of reducing abrasives and shavings. Patent Document 10 discloses a polishing method in which the mixing ratio of alumina and colloidal silica is adjusted in the rough polishing step for the purpose of reducing the residual amount of alumina particles.

JP-A-62-208869 JP 2000-339671 A JP 2003-168661 A JP 2006-95767 A JP 2001-155332 A JP 2009-176597 A JP 2010-135052 A JP 2010-170650 A JP 2012-25873 A JP 2012-43493 A

  With the increase in capacity of magnetic disk drives, the required characteristics for the surface quality of substrates have become more stringent, and in the manufacturing process of magnetic disk substrates, the substrate of protrusion defects (alumina particle such as alumina stabs) while maintaining productivity There is a demand for further reduction of residual defects, polishing scraps, etc.) and dent defects (scratches).

  Therefore, the present invention provides a magnetic disk substrate that can reduce the number of stabs of alumina particles on the substrate surface after the rough polishing step and reduce protrusions and dent defects on the substrate surface after the finish polishing step without impairing productivity. Provide a method.

In one aspect, the present invention includes the following steps (1) to (5), the following steps (1) to (3) are performed by the same polishing machine, and the following step (5) is the polishing machine. The present invention relates to a magnetic disk substrate manufacturing method (hereinafter also referred to as “substrate manufacturing method of the present invention”) performed by another polishing machine.
(1) A polishing composition A containing alumina particles and water is supplied to a surface to be polished of a substrate to be polished, a polishing pad is brought into contact with the surface to be polished, and the polishing pad and / or the substrate to be polished is moved. Polishing the surface to be polished (hereinafter also referred to as “step (1)”),
(2) A step of rinsing the substrate obtained in step (1) (hereinafter also referred to as “step (2)”),
(3) A polishing liquid composition B containing silica particles and water is supplied to the polishing target surface of the substrate obtained in step (2), and the polishing pad is brought into contact with the polishing target surface, and the polishing pad and / or A step of moving the substrate to be polished to polish the surface to be polished (hereinafter also referred to as “step (3)”),
(4) A step of cleaning the substrate obtained in step (3) (hereinafter also referred to as “step (4)”),
(5) Polishing a substrate obtained by the step (4) using a polishing composition C containing colloidal silica particles having an average primary particle size of 5 to 100 nm, an inorganic acid or a salt thereof, an organic phosphonic acid chelating agent and water. Supplying to the target surface, bringing the polishing pad into contact with the polishing target surface, and moving the polishing pad and / or the substrate to be polished to polish the polishing target surface (hereinafter also referred to as “step (5)”).

In another aspect, the present invention includes the following steps (1) to (5), and the following steps (1) to (3) are performed with the same polishing machine, and the following step (5) is performed with the polishing machine. Relates to a magnetic disk substrate polishing method (hereinafter also referred to as “the polishing method of the present invention”) performed by another polishing machine.
(1) A polishing composition A containing alumina particles and water is supplied to a surface to be polished of a substrate to be polished, a polishing pad is brought into contact with the surface to be polished, and the polishing pad and / or the substrate to be polished is moved. Polishing the surface to be polished,
(2) A step of rinsing the substrate obtained in step (1),
(3) A polishing liquid composition B containing silica particles and water is supplied to the polishing target surface of the substrate obtained in step (2), and the polishing pad is brought into contact with the polishing target surface, and the polishing pad and / or Moving the substrate to be polished to polish the surface to be polished;
(4) A step of cleaning the substrate obtained in step (3),
(5) Polishing a substrate obtained by the step (4) using a polishing composition C containing colloidal silica particles having an average primary particle size of 5 to 100 nm, an inorganic acid or a salt thereof, an organic phosphonic acid chelating agent and water. Supplying to a target surface, bringing a polishing pad into contact with the target surface and moving the polishing pad and / or the substrate to be polished to polish the target surface;

  According to the present invention, the alumina sticking on the substrate after the rough polishing step (step (1) to step (3)) and the protrusion and dent defects on the substrate after the final polishing step (step (5)) are reduced. An effect that a substrate with improved quality can be manufactured with high productivity can be achieved.

  The present invention provides a magnetic disk substrate manufacturing method including a rough polishing step and a final polishing step, wherein the rough polishing step is performed using a polishing liquid composition A containing alumina particles and water in the same polishing machine. Of the first rough polishing, the second rough polishing using the polishing composition B containing silica particles and water after the rinse treatment in this order. This is based on the knowledge that alumina sticking on the substrate after rough polishing can be reduced. Furthermore, the present invention provides a polishing composition comprising colloidal silica particles having an average particle size of 5 to 100 nm, an inorganic acid or a salt thereof, an organic phosphonic acid chelating agent, and water after washing the substrate after rough polishing. This is based on the knowledge that by performing final polishing using C, protrusions and dent defects on the substrate after final polishing can be reduced, and the time of the final polishing process can be shortened (productivity improvement).

  In this specification, “alumina piercing” refers to the piercing of the alumina particles after polishing using alumina particles as an abrasive to the substrate. Further, in the present specification, the “protrusion defect” refers to abrasive particles such as alumina and polishing scraps generated during polishing. In the present specification, the “dent defect” means a dent derived from plating, a scratch generated during polishing, and a corrosion pit. The number of protrusion defects and / or the number of dent defects can be evaluated by, for example, microscopic observation of a substrate surface obtained after polishing, observation by a scanning electron microscope, or a surface defect inspection apparatus.

  By using the substrate manufacturing method of the present invention, there is less alumina piercing after the rough polishing process, the protrusions and dent defects after the final polishing process can be effectively reduced, and the reason for improving productivity is not necessarily clear, Estimated as follows. In addition to the conventional rough polishing step (1), a rinsing step (2) and a second rough polishing step (3) using a polishing liquid composition containing silica particles are applied to step (3). By reducing the amount of alumina particles brought in, the frequency of alumina piercing to the substrate after rough polishing is reduced by the mechanical force in step (3) from the start of step (3), and consequently adheres to the substrate. It is estimated that the amount of residual alumina is also reduced. Furthermore, by carrying out the step (5) after cleaning the substrate that has been coarsely polished in the step (4), the amount of alumina particles brought into the final polishing step is reduced, and the organic phosphonic acid system present in the system The chelating agent is adsorbed on the substrate surface to weaken the interaction with the remaining alumina, the alumina sticking is reduced, and the protrusion defect is reduced. In addition, the organic phosphonic acid-based chelating agent is also adsorbed on the surface of the colloidal silica particles, improves the dispersibility of the colloidal silica particles, suppresses the generation of aggregates that cause scratches, and locally exerts a high frictional force. Therefore, it is considered that scratches and dent defects can be reduced while suppressing a decrease in the polishing rate. Thus, it is presumed that productivity is improved because an excellent substrate with few protrusions and dent defects can be efficiently manufactured only through the series of steps (1) to (5), and the polishing time can be shortened. However, the present invention is not limited to these mechanisms.

  Below, the board | substrate manufacturing method of this invention is demonstrated. In general, a magnetic disk is made by polishing a glass substrate that has undergone a fine grinding process or an aluminum alloy substrate that has undergone a Ni-P plating process in a rough polishing process and a final polishing process, and then converted into a magnetic disk in a recording part forming process. Manufactured by.

[Polished substrate]
The substrate to be polished in the substrate manufacturing method of the present invention is a magnetic disk substrate or a substrate used for a magnetic disk substrate, such as a Ni-P plated aluminum alloy substrate, silicate glass, aluminosilicate glass, crystallized glass, tempered glass, etc. Glass substrates, such as glass, are mentioned. Among them, the substrate to be polished used in the present invention is preferably an Ni-P plated aluminum alloy substrate.

  There is no restriction | limiting in particular in the shape of the said to-be-polished substrate, For example, what is necessary is just the shape which has planar parts, such as a disk shape, plate shape, slab shape, prism shape, and the shape which has curved surface parts, such as a lens. Of these, a disk-shaped substrate to be polished is suitable. In the case of a disk-shaped substrate to be polished, the outer diameter is, for example, about 2 to 95 mm, and the thickness is, for example, about 0.5 to 2 mm.

[Step (1): First rough polishing]
In the substrate manufacturing method of the present invention, the polishing liquid composition A containing alumina particles and water is supplied to the surface to be polished of the substrate to be polished, the polishing pad is brought into contact with the surface to be polished, and the polishing pad and / or the above-mentioned A step (step (1)) of moving the substrate to be polished and polishing the surface to be polished; The polishing machine used in the step (1) is not particularly limited, and a known polishing machine for polishing a magnetic disk substrate can be used.

[Step (2): Intermediate rinse]
From the viewpoint of maintaining the polishing rate in the rough polishing process, alumina sticking on the substrate after the rough polishing process, and from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing process, the substrate manufacturing method of the present invention is: After the step (1), the same polishing machine has an intermediate rinsing process (step (2)) for rinsing the substrate obtained in the step (1). Although it does not restrict | limit especially as a rinse liquid used for a rinse process, Water, such as distilled water, ion-exchange water, a pure water, and an ultrapure water, can be used from an economical point. In addition, from the viewpoint of productivity, the step (2) is preferably performed in the same polishing machine without taking out the substrate to be polished from the polishing machine used in the step (1). In the step (2), specifically, a rinsing liquid is supplied to the surface to be polished of the substrate to be polished, a polishing pad is brought into contact with the surface to be polished, and the polishing pad and / or the substrate to be polished is moved to It may include rinsing the surface to be polished. In addition, it is preferable not to have a washing | cleaning process like the process (4) mentioned later between a process (1) and a process (3). Residual alumina can be discharged quickly by the intermediate rinsing treatment step (2) of the present invention, and the effect of the second rough polishing step (3) can be expressed more remarkably. In the present specification, the “rinsing process” refers to a process aimed at discharging abrasive grains and polishing debris remaining on the substrate surface, while dissolving the substrate surface in order to flatten the substrate surface. A process different from a polishing process (chemical mechanical polishing) with abrasive grains.

[Step (3): Second rough polishing]
The substrate manufacturing method of the present invention is a polishing composition comprising silica particles and water from the viewpoint of reducing alumina piercing on a substrate after a rough polishing step, and protrusions and dent defects on the substrate after a final polishing step. B is supplied to the surface to be polished of the substrate obtained in the intermediate rinse treatment step (2), the polishing pad is brought into contact with the surface to be polished, and the polishing pad and / or the substrate to be polished is moved to move the surface to be polished. A step of polishing (step (3)).

  The steps (1) to (3) are the same polishing from the viewpoint of improving productivity, piercing alumina on the substrate after the rough polishing step, and reducing protrusions and dent defects on the substrate after the final polishing step. Perform by machine. Also, from the viewpoint of improving the cleaning efficiency of the next cleaning step (4), it is preferable to perform a rinsing process after the polishing of the step (3).

[Step (4): Washing]
The board | substrate manufacturing method of this invention has the process (process (4)) of wash | cleaning the board | substrate obtained at process (3). From the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step, the cleaning in the step (4) is performed on the substrate subjected to the rough polishing step (steps (1) to (3)) with a cleaning composition. It is preferable to wash with an object. As a cleaning method in the step (4), for example, (a) a method of immersing the substrate obtained in the step (3) in a cleaning composition described later, and / or (b) injecting the cleaning composition. And a method of supplying a cleaning composition onto the surface of the substrate.

  In the method (a), the conditions for immersing the substrate in the cleaning composition are not particularly limited. For example, the temperature of the cleaning composition is 20 to 100 ° C. from the viewpoint of safety and operability. The immersion time is preferably 10 seconds to 30 minutes, and more preferably 2 to 20 minutes, from the viewpoints of cleanability and production efficiency with the cleaning composition. Moreover, it is preferable that ultrasonic vibration is given to the cleaning composition from the viewpoint of improving the removability of the residue and the dispersibility of the residue. The frequency of the ultrasonic wave is preferably 20 to 2000 kHz, more preferably 30 to 1800 kHz, and further preferably 40 to 1500 kHz.

  In the method (b), from the viewpoint of promoting the cleaning property of the residue and the solubility of the oil, the cleaning agent composition to which ultrasonic vibration is applied is injected and the cleaning agent composition is brought into contact with the surface of the substrate. Or cleaning the surface by supplying the cleaning composition onto the surface of the substrate to be cleaned by injection and rubbing the surface supplied with the cleaning composition with a cleaning brush. Is preferred. Furthermore, the cleaning composition to which ultrasonic vibration is applied is supplied to the surface to be cleaned by injection, and the surface to which the cleaning composition is supplied is cleaned by rubbing with a cleaning brush. Is preferred.

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

  In the step (4), in addition to the method (a) and / or the method (b), one or more steps using known cleaning such as swing cleaning, cleaning using rotation of a spinner, paddle cleaning, etc. May be included.

[Step (5): Final polishing]
In the substrate production method of the present invention, the polishing composition C containing colloidal silica particles having an average particle diameter of 5 to 100 nm, an inorganic acid or a salt thereof, an organic phosphonic acid chelating agent and water is obtained in the step (4). Supplying the polishing target surface of the substrate, bringing the polishing pad into contact with the polishing target surface, and moving the polishing pad and / or the substrate to be polished to polish the polishing target surface (step (5)). .

  The polishing machine used in the step (5) prevents the introduction of alumina into the final polishing step, and the steps (1) to (3) from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step. The polishing machine is separate from the polishing machine used in the above. The supply rate of the polishing liquid composition C used in the step (5) and the method of supplying the polishing liquid composition C to the polishing machine can be the same as in the case of the polishing liquid composition A described later.

  The substrate manufacturing method of the present invention includes the aforementioned first rough polishing step (1), intermediate rinse treatment step (2), second rough polishing step (3), cleaning step (4), and finish polishing step. By including (5), it is possible to efficiently manufacture a substrate in which the alumina sticking on the substrate after the rough polishing step and the protrusions and dent defects on the substrate after the final polishing step are effectively reduced.

[Polishing pad of steps (1) to (3)]
There is no restriction | limiting in particular as a polishing pad used by the rough polishing process of process (1)-(3), Polishing pads, such as a suede type, a nonwoven fabric type, a polyurethane independent foam type, or the two-layer type which laminated | stacked these, are used. Although it can be used, a suede type polishing pad is preferable from the viewpoint of improving the polishing rate. A suede type polishing pad is composed of a foam layer having a base layer and spindle-shaped pores perpendicular to the base layer. Examples of the material of the base layer include a non-woven fabric made of natural fibers such as cotton and synthetic fibers, and a base layer obtained by filling a rubber-like substance such as styrene butadiene rubber. Alumina on the substrate after the rough polishing step is used. From the viewpoint of piercing and reducing protrusions and dent defects on the substrate after the finish polishing step, a polyester film is preferable, and a polyethylene terephthalate (PET) film from which a high-hardness resin film can be obtained is more preferable. In addition, examples of the material for the foam layer include polyurethane, polystyrene, polyester, polyvinyl chloride, natural rubber, and synthetic rubber. From the viewpoint of improving the physical properties such as compressibility and improving the abrasion resistance during polishing. Therefore, polyurethane is preferable, and polyurethane elastomer is more preferable.

  Moreover, the average pore diameter of the polishing pad used in the steps (1) to (3) is preferably 10 μm or more, more preferably 20 μm or more, further preferably 30 μm or more, and further preferably 35 μm or more from the viewpoint of improving the polishing rate. More preferably, from the same viewpoint, 100 μm or less is preferable, 80 μm or less is more preferable, 60 μm or less is further preferable, and 55 μm or less is even more preferable.

[Polishing load in step (1)]
In this specification, the polishing load means the pressure of the surface plate applied to the polishing surface of the substrate to be polished during polishing. The polishing load in the step (1) is preferably 25 kPa or less, more preferably 20 kPa or less, from the viewpoint of reducing the alumina piercing on the substrate after the rough polishing step and the protrusions and dent defects on the substrate after the final polishing step. More preferably, it is 15 kPa or less, More preferably, it is 11 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, and even more preferably 9 kPa or more from the viewpoint of reducing the waviness of the substrate surface and improving the polishing rate. Therefore, the polishing load is preferably 3 to 25 kPa, more preferably 5 to 20 kPa, still more preferably 7 to 15 kPa, and even more preferably 9 to 11 kPa. The polishing load can be adjusted by applying air pressure or weight to the surface plate or the substrate.

[Polishing amount in step (1)]
In the step (1), the polishing amount per unit area (1 cm ² ) of the substrate to be polished includes the viewpoint of removing plating defects, the viewpoint of reducing the waviness of the substrate surface, the alumina piercing on the substrate after the rough polishing process, and From the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step, 0.4 mg or more is preferable, more preferably 0.6 mg or more, and still more preferably 0.8 mg or more. On the other hand, from the viewpoint of improving productivity and reducing roll-off, 2.6 mg or less is preferable, more preferably 2.1 mg or less, and even more preferably 1.7 mg or less. Therefore, the polishing amount is preferably 0.4 to 2.6 mg, more preferably 0.6 to 2.1 mg, and still more preferably 0.8 to 1.7 mg.

[Supply speed of polishing composition A]
The supply rate of the polishing liquid composition A in the step (1) is preferably 0.25 mL / min or less, more preferably 0.2 mL / min or less, more preferably 0.15 mL / min per 1 cm ^{2 of the} substrate to be polished, from the viewpoint of economy. More preferred is less than or equal to minutes. The supply rate is preferably 0.01 mL / min or more per 1 cm ^{2 of the} substrate to be polished, more preferably 0.025 mL / min or more, and further preferably 0.05 mL / min or more from the viewpoint of improving the polishing rate. Therefore, the supply rate is preferably 0.01 to 0.25 mL / min per 1 cm ^{2 of the} substrate to be polished, more preferably 0.025 to 0.2 mL / min, and even more preferably 0.05 to 0.15 mL / min. .

[Method of supplying polishing liquid composition A to polishing machine]
Examples of a method for supplying the polishing liquid composition A to the polishing machine include a method in which the polishing liquid composition A is continuously supplied using a pump or the like. When supplying the polishing liquid composition A to the polishing machine, in addition to the method of supplying it with one liquid containing all the components, considering the storage stability of the polishing liquid composition A, a plurality of component liquids for blending It can also be divided into two liquids or more. In the latter case, for example, the plurality of compounding component liquids are mixed into the polishing liquid composition A in the supply pipe or on the substrate to be polished.

[Polishing load in step (2)]
The polishing load in the step (2) is preferably 25 kPa or less, more preferably 20 kPa or less, from the viewpoint of reducing alumina piercing on the substrate after the rough polishing step and reducing protrusions and dent defects on the substrate after the final polishing step. More preferably, it is 15 kPa or less, More preferably, it is 11 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, and even more preferably 9 kPa or more from the viewpoint of improving the polishing rate. Therefore, the polishing load is preferably 3 to 25 kPa, more preferably 5 to 20 kPa, still more preferably 7 to 15 kPa, and even more preferably 9 to 11 kPa. By setting the polishing load within the above range, it is considered that the pushing of alumina particles into the substrate is suppressed and the alumina sticking is effectively reduced.

[Rinse Solution Supply Speed in Step (2)]
The supply speed of the rinsing liquid in the step (2) is such that the alumina sticks on the substrate after the rough polishing step, the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step, and the alumina to the final polishing step. From the viewpoint of preventing carry-in, it is preferably 0.25 mL / min or more per 1 cm ^{2 of the} substrate to be polished, more preferably 0.80 mL / min or more, further preferably 1.0 mL / min or more, and from the same viewpoint. It is preferably 4.0 mL / min or less, more preferably 2.5 mL / min or less, and still more preferably 2.0 mL / min or less. Further, from the viewpoint of reducing alumina piercing on the substrate after the rough polishing process, and protrusions and dent defects on the substrate after the final polishing process, and from the viewpoint of preventing the introduction of alumina into the final polishing process, the process (2 ) Is preferably 5 seconds or longer, more preferably 7 seconds or longer, further preferably 10 seconds or longer, and from the same viewpoint, preferably 60 seconds or shorter, more preferably 30 seconds or shorter, 20 More preferred is less than a second. In addition, the method of supplying the rinse liquid in a process (2) to a polisher can be performed similarly to the method of supplying the above-mentioned polishing liquid composition A to a polisher.

[Polishing load in step (3)]
The polishing load in the step (3) is preferably 25 kPa or less, more preferably 20 kPa or less, from the viewpoint of reducing alumina piercing on the substrate after the rough polishing step and reducing protrusions and dent defects on the substrate after the final polishing step. More preferably, it is 15 kPa or less, More preferably, it is 11 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, and even more preferably 9 kPa or more from the viewpoint of improving the polishing rate. Therefore, the polishing load is preferably 3 to 25 kPa, more preferably 5 to 20 kPa, still more preferably 7 to 15 kPa, and even more preferably 9 to 11 kPa. By setting the polishing load within the above range, it is considered that the pushing of alumina particles into the substrate is suppressed and the alumina sticking is effectively reduced.

[Polishing amount in step (3)]
In the step (3), the polishing amount per unit area (1 cm ² ) of the substrate to be polished is determined in view of reducing alumina sticking on the substrate after the rough polishing step, reducing the carry-in of alumina particles to the final polishing, and From the viewpoint of reducing protrusions and dent defects after finish polishing, the amount is preferably 0.0004 mg or more, more preferably 0.004 mg or more, and further preferably 0.01 mg or more. On the other hand, from the viewpoint of improving productivity, it is preferably 0.85 mg or less, more preferably 0.43 mg or less, further preferably 0.26 mg or less, and even more preferably 0.1 mg or less. Therefore, the polishing amount is preferably 0.0004 to 0.85 mg, more preferably 0.004 to 0.43 mg, still more preferably 0.01 to 0.26 mg, and even more preferably 0.01 to 0.1 mg. It is.

[Supply speed of polishing composition B]
The supply rate of the polishing composition B in the step (3) can be performed in the same manner as the supply rate of the polishing composition A described above.

[Method of supplying polishing liquid composition B to polishing machine]
The method for supplying the polishing liquid composition B to the polishing machine can be performed in the same manner as the method for supplying the polishing liquid composition A to the polishing machine. The polishing liquid composition B is a supply means for supplying the polishing liquid composition A from the viewpoint of reducing alumina piercing on the substrate after the rough polishing step and protrusions and dent defects on the substrate after the final polishing step. It is preferable to supply from different supply means.

  From the viewpoint of reducing alumina sticking on the substrate after the rough polishing process, and suppressing the introduction of alumina into the final polishing process and reducing protrusions and dent defects on the substrate after the final polishing process, the process (3 It is preferable that a step of rinsing the substrate to be polished is also included at the end of the step. As the rinsing liquid, water, ion exchange water, distilled water or the like can be used.

  The polishing load in the rinsing process included in the step (3) is a viewpoint of reducing alumina sticking on the substrate after the rough polishing step, and suppresses the introduction of alumina into the final polishing step, and the substrate after the final polishing step. From the viewpoint of reducing the above protrusion and dent defects, 15 kPa or less is preferable, more preferably 10 kPa or less, still more preferably 5 kPa or less, and from the same viewpoint, 0.2 kPa or more is preferable, and more preferably 0.5 kPa or more. More preferably, it is 1.0 kPa or more.

The supply speed of the rinsing liquid in the rinsing process included in the process (3) is a viewpoint of reducing alumina sticking on the substrate after the rough polishing process, and suppresses the introduction of alumina into the final polishing process, and the final polishing process. From the viewpoint of reducing protrusions and dent defects on the subsequent substrate, it is preferably 0.25 mL / min or more per 1 cm ^{2 of the} substrate to be polished, more preferably 0.8 mL / min or more, further preferably 1.0 mL / min or more. In addition, 4.0 mL / min or less is preferable, more preferably 2.5 mL / min or less, and still more preferably 2.0 mL / min or less. Moreover, the supply time of the rinse liquid in the rinse treatment step is preferably 5 seconds or longer, more preferably 10 seconds or longer, more preferably 30 seconds or shorter, and even more preferably 20 seconds or shorter from the same viewpoint.

[Polishing pad in step (5)]
As the polishing pad used in the step (5), the same type of polishing pad as that used in the steps (1) to (3) may be used. The average pore diameter of the polishing pad used in the step (5) is preferably 1 μm or more, more preferably 2 μm or more, and further preferably 3 μm or more from the viewpoint of reducing protrusions and dent defects on the substrate after the finish polishing step. Moreover, from the same viewpoint, 50 μm or less is preferable, 40 μm or less is more preferable, 30 μm or less is further preferable, and 10 μm or less is even more preferable.

[Polishing load in step (5)]
The polishing load in the step (5) is preferably 25 kPa or less, more preferably 20 kPa or less, still more preferably 15 kPa or less, and even more preferably, from the viewpoint of effectively reducing protrusions and dent defects on the substrate after the finish polishing step. Is 11 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, and even more preferably 9 kPa or more from the viewpoint of reducing the waviness of the substrate surface and improving the polishing rate. Therefore, the polishing load is preferably 3 to 25 kPa, more preferably 5 to 20 kPa, further preferably 7 to 15 kPa, and even more preferably 9 to 11 kPa.

[Polishing amount in step (5)]
In the step (5), the polishing amount per unit area (1 cm ² ) of the substrate to be polished is preferably 0.085 mg or more, more preferably 0 from the viewpoint of reducing protrusions and dent defects on the substrate after finish polishing. .10 mg or more, more preferably 0.13 mg or more, even more preferably 0.15 mg or more. Moreover, from a viewpoint of productivity improvement, 0.85 mg or less is preferable, 0.70 mg or less is more preferable, 0.50 mg or less is further more preferable, and 0.40 mg or less is further more preferable. Accordingly, the polishing amount is preferably 0.085 to 0.85 mg, more preferably 0.10 to 0.70 mg, further preferably 0.13 to 0.50 mg, and even more preferably 0.15 to 0.40 mg. .

[Supply speed of polishing composition C]
The supply rate of the polishing composition C in the step (5) can be performed in the same manner as the supply rate of the polishing composition A described above.

[Method for supplying polishing composition C to polishing machine]
The method for supplying the polishing liquid composition C to the polishing machine can be performed in the same manner as the method for supplying the polishing liquid composition A to the polishing machine.

[Polishing liquid composition A]
The polishing liquid composition A used in the step (1) contains alumina particles from the viewpoint of improving the polishing rate.

[Alumina particles]
Examples of the alumina particles include α-alumina, intermediate alumina, amorphous alumina, fumed alumina, and the like, from the viewpoint of improving the polishing rate, α-alumina is preferable, and alumina piercing on the substrate after the rough polishing step, and From the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step, and from the viewpoint of reducing surface roughness and surface waviness, intermediate alumina is preferred.

  The average secondary particle diameter of the alumina particles is from the viewpoint of reducing the alumina piercing on the substrate after the rough polishing step, reducing protrusions and dent defects on the substrate after the final polishing step, and improving the polishing rate. 1 μm or more is preferable, more preferably 0.15 μm or more, still more preferably 0.25 μm or more, and even more preferably 0.50 μm or more. From the same viewpoint, 0.80 μm or less is preferable, and more preferably 0 .70 μm or less, more preferably 0.68 μm or less, and even more preferably 0.65 μm or less. The average secondary particle diameter can be determined by the method described in the examples.

  The content of the alumina particles in the polishing composition A is from the viewpoint of reducing the alumina piercing on the substrate after the rough polishing step, and the protrusions and dent defects on the substrate after the final polishing step, and improving the polishing rate. 0.01% by mass or more is preferable, 0.05% by mass or more is more preferable, 0.1% by mass or more is further preferable, 1% by mass or more is further more preferable, and 2% by mass or more is further more preferable. From the same viewpoint, it is preferably 30% by mass or less, more preferably 20% by mass or less, further preferably 15% by mass or less, still more preferably 10% by mass or less, and still more preferably 5% by mass or less. Further, the content of alumina particles in the entire abrasive contained in the polishing composition A is preferably 5% by mass or more, more preferably 30% by mass or more, and further preferably 50% by mass or more from the viewpoint of improving the polishing rate. Preferably, 70% by mass or more is even more preferable, and 95% by mass or more is even more preferable.

[Α alumina]
In the present invention, α-alumina is a general term for crystalline alumina particles in which a structure peculiar to α-alumina is recognized in the crystal by X-ray diffraction. The structure unique to α-alumina is, for example, 2θ region 35.1 to 35.3 ° (104 plane), 43.2 to 43.4 ° (113 plane), 57.4 to 57.6 ° in the X-ray diffraction spectrum. This can be confirmed by the presence or absence of a peak having a vertex on (116 plane). In the present application, unless otherwise specified, the α-alumina-specific peak means a peak on the 104 plane.

  The alpha conversion rate of the α alumina is 50% or more from the viewpoint of reducing the alumina piercing on the substrate after the rough polishing step, reducing protrusions and dent defects on the substrate after the final polishing step, and improving the polishing rate. More preferably, it is 65% or more, more preferably 90% or more, and from the same viewpoint, it is preferably 99% or less, more preferably 98% or less, still more preferably 97%. It is as follows. Here, the α conversion rate is 104 derived from 2θ = 35.1-35.3 ° in an X-ray diffraction method using WA-1000 (α alumina having an α conversion rate of 99.9%, manufactured by Showa Denko KK). The numerical value of the relative area of the α-alumina-specific peak when the peak area of the surface is 99.9% can be specifically obtained by the method described in the examples. In addition, a plurality of types of α-alumina having an α conversion rate within the above range may be used.

  The average secondary particle diameter of α-alumina is from the viewpoint of reducing the alumina sticking on the substrate after the rough polishing step, reducing protrusions and dent defects on the substrate after the final polishing step, and improving the polishing rate. 10 μm or more is preferable, more preferably 0.25 μm or more, still more preferably 0.50 μm or more, and even more preferably 0.60 μm or more. From the same viewpoint, 0.80 μm or less is preferable, and more preferably 0 .70 μm or less, more preferably 0.68 μm or less, and even more preferably 0.65 μm or less. The average secondary particle diameter can be determined by the method described in the examples.

  The content of α-alumina in the polishing composition A is from the viewpoint of reducing alumina piercing on the substrate after the rough polishing step, as well as protrusions and dent defects on the substrate after the final polishing step, and improving the polishing rate. , 0.01% by weight or more is preferable, 0.05% by weight or more is more preferable, 0.10% by weight or more is further preferable, 1% by weight or more is further more preferable, 2% by weight or more is further more preferable, From the same viewpoint, it is preferably 30% by mass or less, more preferably 20% by mass or less, further preferably 15% by mass or less, still more preferably 10% by mass or less, and still more preferably 5% by mass or less.

[Intermediate alumina]
The polishing liquid composition A preferably contains intermediate alumina from the viewpoint of reducing alumina piercing on the substrate after the rough polishing step and protrusions and dent defects on the substrate after the final polishing step and improving the polishing rate. . Intermediate alumina is a general term for crystalline alumina particles other than α-alumina, and specifically includes γ-alumina, δ-alumina, θ-alumina, η-alumina, κ-alumina, and mixtures thereof. Among the intermediate aluminas, from the viewpoint of reducing the alumina piercing on the substrate after the rough polishing process, and reducing protrusions and dent defects on the substrate after the final polishing process, and improving the polishing rate, γ alumina, δ alumina, θ Alumina and a mixture thereof are preferable, γ alumina and θ alumina are more preferable, and θ alumina is more preferable.

  The average secondary particle size of the intermediate alumina is 0.01 μm or more from the viewpoint of reducing the alumina sticking on the substrate after the rough polishing step and the protrusions and dent defects on the substrate after the final polishing step and improving the polishing rate. Preferably, it is 0.05 μm or more, more preferably 0.1 μm or more, still more preferably 0.12 μm or more, and from the same viewpoint, it is preferably 0.60 μm or less, more preferably 0.50 μm or less. More preferably, it is 0.40 μm or less, still more preferably 0.30 μm or less, and still more preferably 0.20 μm or less. The average secondary particle diameter can be determined by the same method as in the case of the aforementioned α-alumina.

  Further, the content of the intermediate alumina in the polishing liquid composition A is from the viewpoint of reducing the alumina sticking on the substrate after the rough polishing step and the protrusions and dent defects on the substrate after the final polishing step and improving the polishing rate. 0.001% by mass or more is preferable, more preferably 0.01% by mass or more, still more preferably 0.1% by mass or more, still more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more. From the same viewpoint, it is preferably 27% by mass or less, more preferably 15% by mass or less, further preferably 10% by mass or less, still more preferably 5% by mass or less, and even more preferably 2% by mass or less. It is.

  From the viewpoint of improving the polishing rate, the polishing liquid composition A, the alumina piercing on the substrate after the rough polishing step, and the protrusion and dent defects on the substrate after the final polishing step, as the alumina particles, α-alumina and intermediate It is preferable to contain alumina, and it is more preferable to contain α alumina and θ alumina.

  When α-alumina and intermediate alumina are used, the weight ratio of α-alumina and intermediate alumina (mass% of α alumina / mass% of intermediate alumina) is determined by the alumina piercing on the substrate after the rough polishing process and after the final polishing process. From the viewpoint of reducing protrusions and dent defects on the substrate and improving the polishing rate, 90/10 to 10/90 is preferable, more preferably 85/15 to 40/60, and still more preferably 85/15 to 50/50. Even more preferably 85/15 to 60/40, still more preferably 85/15 to 70/30, and even more preferably 85/15 to 75/25.

[Silica particles]
The polishing composition A preferably further contains silica particles from the viewpoint of reducing alumina sticking on the substrate after the rough polishing step and reducing protrusions and dent defects on the substrate after the final polishing step. Examples of the silica particles include colloidal silica, fumed silica, and surface-modified silica. Among these, colloidal silica is preferable from the viewpoint of reducing alumina sticking on the substrate after the rough polishing step and reducing protrusions and dent defects on the substrate after the final polishing step.

  The average primary particle diameter (D50) of the silica particles is preferably 5 nm or more from the viewpoint of reducing the alumina piercing on the substrate after the rough polishing step, reducing protrusions and dent defects on the substrate after the final polishing step, and improving the polishing rate. More preferably 15 nm or more, still more preferably 30 nm or more, still more preferably 40 nm or more, and from the same viewpoint, preferably 120 nm or less, more preferably 100 nm or less, still more preferably 90 nm or less, and even more preferably 85 nm or less. In addition, this primary particle diameter can be calculated | required by the method as described in an Example.

  Further, the standard deviation of the primary particle diameter of the silica particles is preferably 8 nm from the viewpoint of reducing the alumina piercing on the substrate after the rough polishing step and the protrusion and dent defects on the substrate after the final polishing step and improving the polishing rate. Or more, more preferably 20 nm or more, still more preferably 40 nm or more, still more preferably 60 nm or more, and from the same viewpoint, preferably 90 nm or less, more preferably 85 nm or less, even more preferably 80 nm or less, More preferably, it is 75 nm or less. In addition, this standard deviation can be calculated | required by the method as described in an Example.

  The primary particle diameter (D10) of the silica particles is preferably 1 nm or more from the viewpoint of reducing the number of protrusions and depressions on the substrate after the rough polishing step and the protrusions and dent defects on the substrate after the final polishing step and improving the polishing rate. More preferably, it is 10 nm or more, more preferably 15 nm or more, still more preferably 20 nm or more, and from the same viewpoint, it is preferably 60 nm or less, more preferably 55 nm or less, still more preferably 50 nm or less, and even more preferably 45 nm. It is as follows. In addition, this primary particle diameter (D10) can be calculated | required by the method as described in an Example.

  The primary particle diameter (D90) of the silica particles is preferably 40 nm or more from the viewpoint of reducing the number of protrusions and dents on the substrate after the rough polishing step and the protrusions and dent defects on the substrate after the polishing step and improving the polishing rate. More preferably, it is 60 nm or more, more preferably 80 nm or more, still more preferably 100 nm or more, and from the same viewpoint, it is preferably 150 nm or less, more preferably 140 nm or less, still more preferably 130 nm or less, even more preferably 125 nm. It is as follows. In addition, this primary particle diameter (D90) can be calculated | required by the method as described in an Example.

  When alumina particles and silica particles are used in combination, the weight ratio of alumina particles to silica particles (alumina particle weight / silica particle weight) is determined by the alumina sticking on the substrate after the rough polishing step and the protrusion on the substrate after the final polishing step. From the viewpoint of reducing dent defects and improving the polishing rate, it is preferably 10/90 to 90/10, more preferably 30/70 to 80/20, and further preferably 40/60 to 75/25.

  When alumina particles and silica particles are used in combination, the ratio of the average secondary particle diameter of alumina particles to the average primary particle diameter (D50) of silica particles (alumina particle diameter / silica particle diameter) is determined on the substrate after the rough polishing step. From the viewpoint of reducing protrusion and dent defects on the substrate after the alumina piercing and finish polishing steps and improving the polishing rate, it is preferably 1 or more, more preferably 2 or more, and further preferably 5 or more. From the viewpoint, it is preferably 100 or less, more preferably 50 or less, and still more preferably 20 or less.

  As the content of silica particles contained in the polishing liquid composition A, from the viewpoint of reducing alumina protrusions on the substrate after the rough polishing step and protrusions and dent defects on the substrate after the final polishing step and improving the polishing rate, 0.3 mass% or more is preferable, 0.5 mass% or more is more preferable, 1.0 mass% or more is more preferable, and 1.5 mass% or more is further more preferable. The content is preferably 20% by mass or less, more preferably 15% by mass or less, and still more preferably 10% by mass or less from the viewpoints of economy and reduction of protrusions and dent defects on the substrate after the finish polishing step. 5 mass% or less is still more preferable.

[Polyacrylate]
The polishing composition A preferably contains polyacrylic acid or a salt thereof from the viewpoint of reducing the alumina piercing on the substrate after the rough polishing step and the protrusions and dent defects on the substrate after the final polishing step. The weight average molecular weight of the polyacrylic acid or a salt thereof is preferably 300 or more, more preferably 1000 or more, from the viewpoint of reducing alumina piercing on the substrate after the rough polishing step and protrusions and dent defects on the substrate after the final polishing step. Preferably, 3000 or more is more preferable, 5000 or more is further more preferable, and from the same viewpoint, 300000 or less is preferable, 150,000 or less is more preferable, 50000 or less is further preferable, and 20000 or less is further more preferable. It is considered that the polyacrylate contributes to the improvement of the dispersibility of the alumina particles and suppresses the sticking of alumina and adhesion of alumina. The polyacrylate used in the present invention is water-soluble. Here, “water-soluble” means that the solubility in 100 g of water at 20 ° C. is 2 g or more. The “molecular weight” herein refers to a weight average molecular weight, and the weight average molecular weight can be measured by gel permeation chromatography (GPC) described in Examples.

  The content of the polyacrylate contained in the polishing liquid composition A is improved in the polishing rate, and the alumina stabs on the substrate after the rough polishing step, and the protrusions and dent defects on the substrate after the final polishing step. From a viewpoint of reducing, 0.001 mass% or more is preferable, More preferably, it is 0.005 mass% or more, More preferably, it is 0.01 mass% or more, and 1.0 mass% or less is the same viewpoint. More preferably, it is 0.5 mass% or less, More preferably, it is 0.3 mass% or less, More preferably, it is 0.2 mass% or less.

  The polyacrylate has a structural unit represented by the following general formula.

（式中、Ｒは炭素数１〜３のアルキル基、Ｍは水素、アルカリ金属、アルカリ土類金属、アンモニウム、総炭素数１〜８のアルキル基を有する４級アンモニウムである）

(In the formula, R is an alkyl group having 1 to 3 carbon atoms, M is hydrogen, an alkali metal, an alkaline earth metal, ammonium, or a quaternary ammonium having an alkyl group having 1 to 8 carbon atoms in total)

  The proportion of the structural unit represented by the general formula of the polyacrylate is determined from the viewpoint of reducing alumina piercing on the substrate after the rough polishing step, and protrusions and dent defects on the substrate after the final polishing step. In the total structural unit of acrylic acid, 20 mol% or more is preferable, 40 mol% or more is more preferable, and 60 mol% or more is more preferable.

  Examples of the polyacrylate include poly (meth) acrylic acid, (meth) acrylic acid-maleic acid copolymer, (meth) acrylic acid-itaconic acid copolymer, (meth) acrylic acid fumaric acid copolymer, (Meth) acrylic acid / vinyl acetate copolymer, 2-hydroxyethyl (meth) acrylate / (meth) acrylic acid copolymer, benzoic acid formaldehyde condensate, benzoic acid-phenol-formaldehyde condensate, and salts thereof Polyacrylic acid and its salt are preferable from the viewpoint of reducing alumina piercing on the substrate after the rough polishing step and reducing protrusions and dent defects on the substrate after the final polishing step. These can be used alone or in combination of two or more. “(Meth) acrylic acid” represents “acrylic acid and methacrylic acid”. The same applies to “(meth) acrylate”. In addition, as counter ions in the case of each salt, alkali metal salts such as sodium and potassium, ammonium salts, primary amine salts such as monoethanolamine, secondary amine salts such as diethanolamine, and tertiary amines such as triethanolamine Examples thereof include salts and quaternary ammonium salts such as tetramethylammonium.

[Polyoxyethylene alkyl ether phosphoric acid]
Polishing fluid composition A preferably contains polyoxyethylene alkyl ether phosphoric acid. It is considered that polyoxyethylene alkyl ether phosphoric acid contributes to the improvement of the dispersibility of alumina particles and suppresses the sticking of alumina and adhesion of alumina. The polyoxyethylene alkyl ether phosphoric acid used in the present invention is water-soluble. Here, “water-soluble” means that the solubility in 100 g of water at 20 ° C. is 2 g or more.

  The polyoxyethylene alkyl ether phosphoric acid is represented by the following general formula.

［前記式において、Ｒ¹は炭素数３〜２０の直鎖若しくは分岐鎖のアルキル基、フェニル基、又は、炭素数３〜２０の直鎖若しくは分岐鎖のアルキル基で置換されたフェニル基を表し、ｍは１〜２０の整数を表し、Ｘは−ＯＭ又は下記一般式（ＩＩ）を表し、Ｍは水素、無機アルカリイオン又は有機アルカリイオンを表す。］

［前記式ＩＩにおいて、Ｒ²は炭素数３〜２０の直鎖若しくは分岐鎖のアルキル基、フェニル基、又は、炭素数３〜２０の直鎖若しくは分岐鎖のアルキル基で置換されたフェニル基を表し、ｎは１〜２０の整数を表す。］

[In the above formula, R ¹ represents a linear or branched alkyl group having 3 to 20 carbon atoms, a phenyl group, or a phenyl group substituted with a linear or branched alkyl group having 3 to 20 carbon atoms. , M represents an integer of 1 to 20, X represents -OM or the following general formula (II), and M represents hydrogen, an inorganic alkali ion or an organic alkali ion. ]

[In Formula II, R ² represents a linear or branched alkyl group having 3 to 20 carbon atoms, a phenyl group, or a phenyl group substituted with a linear or branched alkyl group having 3 to 20 carbon atoms. N represents an integer of 1-20. ]

From the viewpoint of reducing alumina sticking on the substrate after the rough polishing step and reducing protrusions and dent defects on the substrate after the final polishing step, R ² is a linear or branched chain having 10 to 18 carbon atoms. The alkyl group is preferably a linear or branched alkyl group having 10 to 16 carbon atoms, and from the same viewpoint, m is preferably an integer of 1 to 10, preferably an integer of 1 to 6, From the same viewpoint, X is preferably -OM, M is preferably hydrogen or sodium, and more preferably sodium.

  The weight average molecular weight of polyoxyethylene alkyl ether phosphoric acid reduces the polishing rate, reduces alumina sticking on the substrate after the rough polishing process, and reduces protrusions and dent defects on the substrate after the final polishing process. 200 or more, more preferably 250 or more, still more preferably 300 or more, and from the same viewpoint, it is preferably 10,000 or less, more preferably 8000 or less, still more preferably 5000 or less, and even more preferably. Is 1000 or less. In addition, this weight average molecular weight can be calculated | required on the conditions as described in an Example.

  The content of the polyoxyethylene alkyl ether phosphoric acid contained in the polishing liquid composition A is improved in the polishing rate and pierced alumina on the substrate after the rough polishing step, and protrusions on the substrate after the final polishing step and From the viewpoint of reducing dent defects, 0.001% by mass or more is preferable, more preferably 0.005% by mass or more, still more preferably 0.010% by mass or more, and from the same viewpoint, 1.0% by mass. % Or less, more preferably 0.5% by mass or less, still more preferably 0.3% by mass or less, and even more preferably 0.2% by mass or less.

[acid]
The polishing composition A preferably contains an acid from the viewpoint of improving the polishing rate and from the viewpoint of reducing alumina sticking on the substrate after the rough polishing step. Use of the acid in the polishing liquid composition A includes use of an acid and / or a salt thereof. Examples of acids used include nitric acid, sulfuric acid, sulfurous acid, persulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, phosphonic acid, phosphinic acid, pyrophosphoric acid, tripolyphosphoric acid, amidosulfuric acid, 2-aminoethylphosphonic acid, and the like. 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), ethane-1,1, -diphosphonic acid, ethane-1, 1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1-hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid , Methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2 Organic phosphonic acids such as 3,4-tricarboxylic acid and α-methylphosphonosuccinic acid, aminocarboxylic acids such as glutamic acid, picolinic acid and aspartic acid, citric acid, tartaric acid, oxalic acid, nitroacetic acid, maleic acid, oxaloacetic acid, etc. And carboxylic acid. Among these, phosphoric acid, sulfuric acid, citric acid, tartaric acid, maleic acid, 1-hydroxyethylidene-1 are used from the viewpoint of improving the polishing rate, reducing alumina sticking on the substrate after the rough polishing step, and suppressing roll-off deterioration. 1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid) and salts thereof are more preferred, and sulfuric acid and citric acid are more preferred.

  These acids and salts thereof may be used alone or in admixture of two or more, but from the viewpoint of improving the polishing rate, piercing alumina on the substrate after the rough polishing step, and on the substrate after the final polishing step It is preferable to use a mixture of two or more of them from the viewpoint of reducing the protrusion and dent defects of the material selected from the group consisting of phosphoric acid, sulfuric acid, citric acid, tartaric acid and 1-hydroxyethylidene-1,1-diphosphonic acid. It is more preferable to use a mixture of two or more acids, and it is more preferable that sulfuric acid and citric acid are mixed.

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

  The content of the acid in the polishing liquid composition A is improved from the viewpoint of improving the polishing rate, sticking alumina on the substrate after the rough polishing step, and reducing protrusions and dent defects on the substrate after the final polishing step. 0.001% by mass or more is preferable, more preferably 0.01% by mass or more, still more preferably 0.05% by mass or more, and still more preferably 0.1% by mass or more. It is preferably at most 4 mass%, more preferably at most 3 mass%, even more preferably at most 2 mass%, still more preferably at most 1 mass%.

[Oxidant]
The polishing liquid composition A contains an oxidizer from the viewpoint of improving the polishing rate, reducing the number of protrusions and dent defects on the substrate after the final polishing process, and the alumina piercing on the substrate after the rough polishing process. It is preferable to do. As the oxidizing agent, from the viewpoint of improving the polishing rate, the piercing of alumina on the substrate after the rough polishing step, and the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step, peroxide, permanganic acid Or a salt thereof, chromic acid or a salt thereof, peroxo acid or a salt thereof, oxygen acid or a salt thereof, metal salts, and the like. Among these, hydrogen peroxide, iron (III) nitrate, peracetic acid, ammonium peroxodisulfate, iron (III) sulfate, and iron (III) ammonium sulfate are preferable. From the viewpoint of improving the polishing rate, metal ions adhere to the substrate surface. Of these, hydrogen peroxide is more preferable from the viewpoint of being used for general purposes and inexpensive. These oxidizing agents may be used alone or in admixture of two or more.

  The content of the oxidizing agent in the polishing liquid composition A is preferably 0.01% by mass or more, more preferably 0, from the viewpoints of improving the polishing rate and reducing alumina sticking on the substrate after the rough polishing step. 0.05 mass% or more, more preferably 0.10 mass% or more, from the viewpoint of improving the polishing rate, from the viewpoint of reducing alumina sticking on the substrate after the rough polishing step, and the protrusion on the substrate after the final polishing step And from a viewpoint of reducing a dent defect, Preferably it is 4.0 mass% or less, More preferably, it is 2.0 mass% or less, More preferably, it is 1.5 mass% or less. The content is preferably 0.01 to 4.0% by mass, more preferably 0.05 to 2.0% by mass, still more preferably 0.1 to 1.5% by mass, and even more preferably 0.1. It is -1.0 mass%.

[water]
Polishing liquid composition A contains water as a medium. As water, distilled water, ion-exchanged water, pure water, ultrapure water, or the like can be used. The content of water in the polishing liquid composition A is preferably 55% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and even more because the handling of the polishing liquid composition becomes easy. Preferably, it is 85 mass% or more, and from the same viewpoint, 99 mass% or less is preferable, More preferably, it is 98 mass% or less, More preferably, it is 97 mass% or less.

[Other ingredients]
In the polishing composition A, other components can be blended as necessary. Examples of other components include a thickener, a dispersant, a rust inhibitor, a basic substance, a surfactant, and a polymer compound. It is preferable to mix | blend content of these other arbitrary components in polishing liquid composition A in the range which does not impair the effect of this invention, 0-10 mass% is preferable, and 0-5 mass% is more preferable.

[PH of polishing composition A]
The pH of the polishing composition A is the viewpoint of improving the polishing rate, the viewpoint of reducing the alumina sticking on the substrate after the rough polishing step and the protrusion and dent defects on the substrate after the final polishing step, and the corrosion of the polishing machine used. From the viewpoint of prevention, the pH is preferably adjusted to 1.0 to 6.0, more preferably pH 1.0 to 4.0, still more preferably pH 1.0 to 1.0, using the aforementioned acid or a known pH adjuster. 3.0, even more preferably pH 1.0-2.0. In addition, said pH is pH of polishing liquid composition in 25 degreeC, can be measured using a pH meter, and is a numerical value 40 minutes after immersion of an electrode.

[Method for Preparing Polishing Liquid Composition A]
The polishing liquid composition A can be prepared, for example, by mixing alumina particles and water and, if desired, silica particles, a predetermined additive, an oxidizing agent, an acid and other components by a known method. When mixing silica particles, they may be mixed in a concentrated slurry, or may be mixed after being diluted with water or the like. As another embodiment, the polishing liquid composition A may be prepared as a concentrate. The mixing is not particularly limited, and can be performed using a homomixer, a homogenizer, an ultrasonic disperser, a stirrer such as a wet ball mill, or the like.

[Polishing liquid composition B]
The polishing liquid composition B used in the step (3) includes silica particles and water from the viewpoint of reducing alumina sticking on the substrate after the rough polishing step and protrusions and dent defects on the substrate after the final polishing step. Containing. The silica particles used are the same as the silica particles used in the polishing composition A, and are preferably colloidal silica.

  The average primary particle diameter (D50) of the silica particles used in the polishing liquid composition B is from the viewpoint of reducing alumina piercing on the substrate after the rough polishing step and protrusions and dent defects on the substrate after the final polishing step. , Preferably 5 nm or more, more preferably 15 nm or more, still more preferably 30 nm or more, even more preferably 40 nm or more, and from the same viewpoint, preferably 120 nm or less, more preferably 100 nm or less, Preferably it is 90 nm or less, More preferably, it is 85 nm or less. When the average primary particle diameter (D50) of the silica particles is within the above range, it is considered that the frictional force at the time of polishing cutting is increased, and alumina sticking is effectively reduced. In addition, this average primary particle diameter can be calculated | required by the method as described in an Example.

  In addition, the standard deviation of the primary particle diameter of the silica particles used in the polishing liquid composition B is based on the viewpoint of reducing alumina sticking on the substrate after the rough polishing step, and the protrusions and dent defects on the substrate after the final polishing step. From the viewpoint of reduction, it is preferably 8 nm or more, more preferably 20 nm or more, further preferably 40 nm or more, further preferably 60 nm or more, and from the same viewpoint, preferably 90 nm or less, more preferably 85 nm or less, and further preferably Is 80 nm or less, more preferably 75 nm or less. When the standard deviation of the primary particle diameter is within the above range, the frictional force at the time of polishing and cutting is further improved, the alumina particles stuck in the step (1) are efficiently pulled out, and the alumina sticking is reduced. Conceivable. In addition, this standard deviation can be calculated | required by the method as described in an Example.

  The primary particle diameter (D10) of the silica particles used in the polishing liquid composition B reduces the amount of alumina sticking on the substrate after the rough polishing step, and reduces protrusions and dent defects on the substrate after the final polishing step. From the viewpoint, it is preferably 1 nm or more, more preferably 10 nm or more, still more preferably 15 nm or more, still more preferably 20 nm or more, and from the same viewpoint, preferably 60 nm or less, more preferably 55 nm or less, still more preferably 50 nm or less, still more preferably 45 nm or less. In addition, this primary particle diameter (D10) can be calculated | required by the method as described in an Example.

  The primary particle diameter (D90) of the silica particles used in the polishing liquid composition B reduces the amount of alumina sticking on the substrate after the rough polishing step, and reduces protrusions and dent defects on the substrate after the final polishing step. From the viewpoint, it is preferably 40 nm or more, more preferably 60 nm or more, still more preferably 80 nm or more, still more preferably 100 nm or more, and from the same viewpoint, preferably 150 nm or less, more preferably 140 nm or less, still more preferably It is 130 nm or less, more preferably 125 nm or less. In addition, this primary particle diameter (D90) can be calculated | required by the method as described in an Example.

  The content of the silica particles contained in the polishing composition B is 0 from the viewpoint of reducing alumina sticking on the substrate after the rough polishing step and reducing the protrusions and dent defects on the substrate after the final polishing step. It is preferably 3% by mass or more, more preferably 0.5% by mass or more, further preferably 1% by mass or more, and still more preferably 2% by mass or more. Further, the content is preferably 20% by mass or less, more preferably 15% by mass or less, still more preferably 10% by mass or less, and still more preferably 6% by mass or less from the viewpoint of economy. Therefore, the content of silica particles is preferably 0.3 to 20% by mass, more preferably 0.5 to 15% by mass, still more preferably 1.0 to 10% by mass, and even more preferably 2.0 to 6%. % By mass.

  Further, the content of silica particles in the entire polishing material contained in the polishing liquid composition B is determined from the viewpoint of reducing alumina sticking on the substrate after the rough polishing step, and the protrusions and depressions on the substrate after the final polishing step. From the viewpoint of reducing the content, it is preferably 60% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, and still more preferably 100% by mass. The content of alumina particles in the entire abrasive contained in the polishing composition B is preferably 40% by mass or less, more preferably 20% by mass or less, and still more preferably 10% by mass or less, from the same viewpoint. Even more preferably, it is substantially free of alumina particles.

  The polishing liquid composition B is an acid, from the viewpoint of improving the polishing rate, from the viewpoint of reducing alumina sticking on the substrate after the rough polishing process, and from the viewpoint of reducing protrusions and depressions on the substrate after the final polishing process. It is preferable to contain an oxidizing agent. Preferred acids and oxidizing agents are the same as in the case of the polishing composition A described above. Also, the water used for the polishing liquid composition B, the pH of the polishing liquid composition B, and the method for preparing the polishing liquid composition B are the same as in the case of the polishing liquid composition A described above.

[Polishing liquid composition C]
The polishing liquid composition C used in the step (5) contains colloidal silica particles from the viewpoint of reducing protrusions and dent defects after finish polishing and improving the polishing rate. Moreover, it is preferable that the polishing liquid composition C does not contain alumina particles from the viewpoint of reducing protrusion defects on the substrate after the finish polishing step.

  The average primary particle diameter (D50) of the silica particles used in the polishing liquid composition C is 5 nm or more, preferably 8 nm or more, more preferably from the viewpoint of reducing protrusions and dent defects on the substrate after finish polishing. From the same viewpoint, it is 100 nm or less, preferably 60 nm or less, more preferably 40 nm or less, and further preferably 20 nm or less. In addition, this average primary particle diameter can be calculated | required by the method as described in an Example.

  Further, the standard deviation of the primary particle diameter of the silica particles is preferably 1 nm or more, more preferably 5 nm or more, further preferably 8 nm or more, and even more, from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step. Preferably, it is 10 nm or more, and from the same viewpoint, 60 nm or less is preferable, more preferably 45 nm or less, still more preferably 30 nm or less, and even more preferably 15 nm or less. In addition, this standard deviation can be calculated | required by the method as described in an Example.

  The primary particle diameter (D10) of the silica particles is preferably 1 nm or more, more preferably 5 nm or more, still more preferably 8 nm or more, and even more preferably from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step. From the same viewpoint, it is preferably 50 nm or less, more preferably 30 nm or less, still more preferably 25 nm or less, and even more preferably 20 nm or less. In addition, this primary particle diameter (D10) can be calculated | required by the method as described in an Example.

  The primary particle diameter (D90) of the silica particles is preferably 1 nm or more, more preferably 5 nm or more, still more preferably 10 nm or more, and even more preferably from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step. From the same viewpoint, it is preferably 150 nm or less, more preferably 80 nm or less, still more preferably 30 nm or less, and even more preferably 25 nm or less. In addition, this primary particle diameter (D90) can be calculated | required by the method as described in an Example.

  The content of the silica particles contained in the polishing composition C is preferably 0.3% by mass or more, more preferably 0.5% by mass from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing process. Above, more preferably 1.0% by mass or more, still more preferably 2.0% by mass or more, and from the same viewpoint, 20% by mass or less is preferable, more preferably 15% by mass or less, still more preferably. It is 10 mass% or less, More preferably, it is 6 mass% or less.

[acid]
Polishing liquid composition C contains an inorganic acid or a salt thereof from the viewpoint of improving the polishing rate and from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step. Inorganic acids include nitric acid, sulfuric acid, sulfurous acid, persulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid, polyphosphoric acid, from the viewpoint of improving the polishing rate and reducing the protrusions and dent defects on the substrate after the final polishing process. , Molybdic acid, phosphonic acid, phosphinic acid, pyrophosphoric acid, tripolyphosphoric acid, amidosulfuric acid and the like. Among these, phosphoric acid, sulfuric acid, and salts thereof are more preferable from the viewpoint of improving the polishing rate and from the viewpoint of reducing alumina sticking on the substrate after the rough polishing step.

  These acids and salts thereof may be used alone or in combination of two or more, but two or more are used from the viewpoint of improving the polishing rate and reducing protrusions and dent defects on the substrate after the final polishing step. It is preferable to use an inorganic acid containing phosphorus or a salt thereof and an inorganic acid not containing phosphorus or a salt thereof, and more preferably using phosphoric acid or sulfuric acid.

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

  The content of the acid in the polishing composition C is preferably 0.001% by mass or more, more preferably 0, from the viewpoint of improving the polishing rate and reducing protrusions and dent defects on the substrate after the final polishing step. 0.01% by mass or more, more preferably 0.05% by mass or more, still more preferably 0.1% by mass or more, and from the same viewpoint, 5% by mass or less is preferable, and more preferably 4% by mass or less. More preferably, it is 3% by mass or less, and still more preferably 2% by mass or less.

[Oxidant]
The polishing composition C preferably contains an oxidizing agent from the viewpoint of improving the polishing rate and reducing the protrusions and dent defects on the substrate after the final polishing step. As the oxidizing agent, from the viewpoint of improving the polishing rate, and reducing the protrusions and dent defects on the substrate after the final polishing step, peroxide, permanganic acid or a salt thereof, chromic acid or a salt thereof, peroxo acid or The salt, oxygen acid or its salt, metal salts, etc. are mentioned. Among these, hydrogen peroxide, iron (III) nitrate, peracetic acid, ammonium peroxodisulfate, iron (III) sulfate, and iron (III) ammonium sulfate are preferable. From the viewpoint of improving the polishing rate, metal ions adhere to the substrate surface. Of these, hydrogen peroxide is more preferable from the viewpoint of being used for general purposes and inexpensive. These oxidizing agents may be used alone or in admixture of two or more.

  The content of the oxidizing agent in the polishing liquid composition C is preferably 0.01% by mass or more, more preferably from the viewpoint of improving the polishing rate and from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step. Is 0.05% by mass or more, more preferably 0.10% by mass or more, and preferably 4.0 from the viewpoint of improving the polishing rate and reducing protrusions and dent defects on the substrate after the final polishing step. It is not more than mass%, more preferably not more than 2.0 mass%, still more preferably not more than 1.5 mass%. The content is preferably 0.01 to 4.0% by mass, more preferably 0.05 to 2.0% by mass, still more preferably 0.1 to 1.5% by mass, and even more preferably 0.1. It is -1.0 mass%.

[water]
Polishing liquid composition C contains water as a medium. As water, distilled water, ion-exchanged water, pure water, ultrapure water, or the like can be used. The content of water in the polishing liquid composition A is preferably 55 to 99% by mass, more preferably 70 to 98% by mass, and still more preferably 80 to 97% by mass, because the handling of the polishing liquid composition becomes easy. Even more preferably, it is 85 to 97% by mass.

[Organic phosphonic acid chelating agent]
The polishing composition C contains an organic phosphonic acid chelating agent from the viewpoint of improving the polishing rate and reducing the protrusions and dent defects on the substrate after the final polishing step. Examples of organic phosphonic acid-based chelating agents include 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), phosphonobutanetricarboxylic acid (PBTC), aminotrismethylenephosphonic acid (NTMP), hexamethylenediaminetetramethylenephosphonic acid, and These salts are mentioned. Among these, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP) is preferable from the viewpoint of improving the polishing rate and reducing protrusions and dent defects on the substrate after the finish polishing step.

  The content of the organic phosphonic acid chelating agent in the polishing liquid composition C is preferably 0.01% by mass from the viewpoint of improving the polishing rate and reducing protrusions and dent defects on the substrate after the final polishing step. Above, more preferably 0.05% by mass or more, and further preferably 0.1% by mass or more, preferably from the viewpoint of improving the polishing rate, from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step Is 4% by mass or less, more preferably 2% by mass or less, further preferably 1.5% by mass or less, and still more preferably 1% by mass or less. The content is preferably 0.01 to 4% by mass, more preferably 0.05 to 2% by mass, still more preferably 0.1 to 1.5% by mass, and even more preferably 0.1 to 1% by mass. It is.

[Anionic polymer]
The polishing composition C preferably contains an anionic polymer from the viewpoint of improving the polishing rate and reducing protrusions and dent defects on the substrate after the final polishing step. The anionic polymer adsorbs to the polishing pad during polishing, forms a hydrated layer on the surface of the polishing pad, suppresses vibration of the polishing pad, further improves the dispersibility of the silica particles, and causes scratches. It is considered that the generation of aggregates can be suppressed. The anionic polymer is water-soluble. Here, “water-soluble” means that the solubility in 100 g of water at 20 ° C. is 2 g or more.

  Examples of the anionic group of the anionic polymer include a carboxylic acid group, a sulfonic acid group, a sulfate ester group, a phosphate ester group, and a phosphonic acid group. These anionic groups may be in the form of a salt. The anionic polymer is preferably an anionic polymer having at least one of a sulfonic acid group and a carboxylic acid group from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step, and an anionic polymer having a sulfonic acid group. A polymer is more preferred.

  When the anionic group forms a salt, there is no particular limitation, and specific examples include salts with metals, ammonium, alkylammonium, and the like. Specific examples of the metal include metals belonging to the periodic table (long-period type) 1A, 1B, 2A, 2B, 3A, 3B, 4A, 6A, 7A, or Group 8. Specific examples of alkylammonium include tetramethylammonium, tetraethylammonium, tetrabutylammonium and the like. Among these, from the viewpoint of reducing protrusions and dent defects after finish polishing, metals belonging to Group 1A, 3B, or 8 and ammonium are preferred, metals belonging to Group 1A, ammonium are more preferred, and ammonium, sodium and potassium are preferred. Further preferred.

  The anionic polymer can be obtained, for example, by polymerizing a monomer having an anionic group such as a monomer having a sulfonic acid group or a monomer having a carboxylic acid group. The polymerization of these monomers may be random, block or graft, but is preferably random.

  Specific examples of the monomer having a sulfonic acid group include isoprene sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, styrene sulfonic acid, methallyl sulfonic acid, vinyl sulfonic acid, allyl sulfonic acid, iso Examples include amylene sulfonic acid and naphthalene sulfonic acid. Examples of the monomer having a carboxylic acid group include itaconic acid, (meth) acrylic acid, maleic acid and the like. Examples of the monomer having a phosphate ester group or a phosphonic acid group include vinylphosphonic acid, methacryloyloxymethyl phosphoric acid, methacryloyloxyethyl phosphoric acid, methacryloyloxybutyl phosphoric acid, methacryloyloxyhexyl phosphoric acid, Examples include methacrylyloxyoctyl phosphoric acid, methacrylyloxydecyl phosphoric acid, methacryloyloxylauryl phosphoric acid, metalloyloxystearyl phosphoric acid, methacryloyloxy 1,4-dimethylcyclohexylphosphoric acid.

  Moreover, monomers other than the above can also be used for the anionic polymer. Examples of other monomers include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-methylstyrene, methyl (meth) acrylate, ethyl (meth) acrylate, and (meth) acrylic acid. (Meth) acrylic acid alkyl esters such as octyl, aliphatic conjugated dienes such as butadiene, isoprene, 2-chloro-1,3-butadiene, 1-chloro-1,3-butadiene, and cyanation of (meth) acrylonitrile A vinyl compound is mentioned.

  As a preferred specific example of the anionic polymer, those having a sulfonic acid group (salt) and an aromatic group in the main chain are preferable from the viewpoint of reducing protrusions and depressions on the substrate after the final polishing step. Specific examples include naphthalene sulfonic acid formaldehyde condensate, methyl naphthalene sulfonic acid formaldehyde condensate, polyalkylaryl sulfonic acid compound such as anthracene sulfonic acid formaldehyde; melamine formalin resin sulfone compound such as melamine sulfonic acid formaldehyde condensate; lignin Examples include lignin sulfonic acid compounds such as sulfonic acid and modified lignin sulfonic acid; and aromatic amino sulfonic acid compounds such as aminoaryl sulfonic acid-phenol-formaldehyde condensates. Naphthalene sulfonic acid compounds such as sulfonic acid formaldehyde condensate, methyl naphthalene sulfonic acid formaldehyde condensate, lignin sulfonic acid compound, aromatic Aminosulfonic acid compounds and their salts are particularly preferred. Among the naphthalene sulfonic acid compounds, naphthalene sulfonic acid formaldehyde condensate, methyl naphthalene sulfonic acid formaldehyde condensate and salts thereof are particularly preferable.

  When the final polishing in the step (5) contains a sulfonic acid (group) salt and an anionic polymer having an aromatic group in the main chain, the dispersibility of the colloidal silica particles is improved and the generation of aggregates causing dent defects Since the frictional vibration during polishing is reduced and the appropriate frictional force is applied to the substrate surface more evenly and the high frictional force is not applied locally, it is possible to scratch while suppressing the decrease in the polishing rate. Can be reduced.

  The weight average molecular weight of the anionic polymer is preferably 500 or more, more preferably 1000 or more, still more preferably 2000 or more, even more from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing step. Preferably, it is 3000 or more, and from the same viewpoint, it is preferably 100,000 or less, more preferably 50,000 or less, still more preferably 30,000 or less, and even more preferably 20,000 or less. The weight average molecular weight can be determined by the method described in Examples using gel permeation chromatography (GPC).

  The content of the anionic polymer in the polishing liquid composition C is preferably 0.001% by mass or more, more preferably 0.003% by mass, from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing process. Or more, more preferably 0.005% by mass or more, still more preferably 0.008% by mass or more, and from the same viewpoint, 1.0% by mass or less is preferable, more preferably 0.5% by mass or less. More preferably, it is 0.1% by mass or less, and still more preferably 0.03% by mass or less.

  Further, the content ratio [silica particle content (mass%) / anionic polymer content (mass%)] of the silica particles and the anionic polymer in the polishing composition C is determined on the substrate after the final polishing process. From the viewpoint of reducing the protrusion defects, 0.1 to 30000 is preferable, more preferably 0.5 to 10000, still more preferably 5 to 5000, and still more preferably 50 to 500.

[Surface cleaner]
The polishing composition C preferably contains a surface cleaner from the viewpoint of improving the polishing rate and reducing protrusions and dent defects on the substrate after the final polishing step. It is considered that the surface cleaning agent improves the wettability of the colloidal silica particles and the substrate surface, is effective in preventing the adhesion of polishing scraps, and can reduce protrusion defects. Examples of the surface cleaning agent include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol, but ethylene glycol and diethylene glycol are preferable from the viewpoint of reducing protrusions and recesses on the substrate after the final polishing step. In particular, ethylene glycol is more preferable. When ethylene glycol or the like is included in the final polishing in the step (5), it is considered that the colloidal silica particles and the substrate surface are improved in wettability, effective in preventing adhesion of polishing debris, and projection defects can be reduced. The anionic polymer is water-soluble. Here, “water-soluble” means that the solubility in 100 g of water at 20 ° C. is 2 g or more.

  The content of the surface cleaner in the polishing composition C is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, from the viewpoint of reducing protrusions and dent defects on the substrate after the final polishing process. More preferably, it is 0.1% by mass or more, still more preferably 0.5% by mass or more, and from the same viewpoint, it is preferably 2% by mass or less, more preferably 1.5% by mass or less, still more preferably Is 1.2% by mass or less, and more preferably 1.0% by mass or less.

  In the polishing composition C, other components can be blended as necessary. Examples of other components include a thickener, a dispersant, a rust inhibitor, a basic substance, a surfactant, and a polymer compound. It is preferable to mix | blend content of these other arbitrary components in polishing liquid composition C in the range which does not impair the effect of this invention, 0-10 mass% is preferable, and 0-5 mass% is more preferable.

[PH of polishing composition C]
From the viewpoint of improving the polishing rate, reducing the protrusions and dent defects on the substrate after the final polishing step, and preventing corrosion of the used polishing machine, the pH of the polishing composition C is not limited to the above-mentioned acids and known ones. It is preferable to adjust to pH 1.0 to 6.0 using a pH adjuster, more preferably pH 1.0 to 4.0, still more preferably pH 1.0 to 3.0, and even more preferably pH 1.0. ~ 2.5. In addition, said pH is pH of polishing liquid composition in 25 degreeC, can be measured using a pH meter, and is a numerical value 40 minutes after immersion of an electrode.

[Method for Preparing Polishing Liquid Composition C]
Polishing liquid composition C can be prepared by, for example, mixing silica particles, inorganic acid or salt thereof, organic phosphonic acid chelating agent and water, and, if desired, an oxidizing agent and other components by a known method. . When mixing silica particles, they may be mixed in a concentrated slurry, or may be mixed after being diluted with water or the like. As another embodiment, the polishing liquid composition C may be prepared as a concentrate. The mixing is not particularly limited, and can be performed using a homomixer, a homogenizer, an ultrasonic disperser, a stirrer such as a wet ball mill, or the like.

[Cleaning composition]
In the cleaning in the step (4), it is preferable to use a cleaning composition. As said cleaning composition, what contains an alkaline agent, water, and various additives as needed can be used.

[Alkaline agent]
The alkaline agent used in the cleaning composition may be either an inorganic alkaline agent or an organic alkaline agent. Examples of the inorganic alkaline agent include ammonia, potassium hydroxide, and sodium hydroxide. Examples of the organic alkali agent include one or more selected from the group consisting of hydroxyalkylamine, tetramethylammonium hydroxide, and choline. These alkaline agents may be used alone or in combination of two or more.

  As the alkali agent of the cleaning composition, potassium hydroxide, sodium hydroxide, monoethanolamine, methyldiethanolamine, from the viewpoint of availability, improvement of dispersibility of residues on the substrate, and improvement of storage stability, And at least one selected from the group consisting of aminoethylethanolamine, more preferably at least one selected from the group consisting of potassium hydroxide and sodium hydroxide.

  The content of the alkaline agent in the cleaning composition is 0.05% by mass or more from the viewpoint of developing a high cleaning property with respect to the residue on the substrate of the cleaning composition and enhancing safety during handling. Preferably, it is 0.08% by mass or more, and from the same viewpoint, it is preferably 10% by mass or less, and more preferably 3% by mass or less.

  From the viewpoint of improving the dispersibility of the residue on the substrate, the pH of the cleaning composition is preferably 8 to 13, more preferably 9 to 13, still more preferably 10 to 13, and even more preferably 11. ~ 13. In addition, said pH is pH of the cleaning composition in 25 degreeC, can be measured using a pH meter (Toa Denpa Kogyo Co., Ltd., HM-30G), and 40 minutes after immersion in the cleaning composition of an electrode It is the latter number.

[Various additives]
In addition to alkaline agents, the detergent composition includes nonionic surfactants, chelating agents, anionic surfactants such as ether carboxylates or fatty acids, water-soluble polymers, antifoaming agents (surfactants corresponding to the components) May be included), alcohols, preservatives, antioxidants, and the like.

  The content of components other than water contained in the cleaning composition is the content of water and water from the viewpoint of improving the dispersibility of the residue on the substrate and improving the storage stability during concentration and use. When the total content of other components is 100% by mass, it is preferably 10 to 60% by mass, more preferably 15 to 50% by mass, and further preferably 15 to 40% by mass.

  The said detergent composition is diluted and used from a viewpoint of workability | operativity. The dilution rate is preferably 10 to 500 times, more preferably 20 to 200 times, and still more preferably 50 to 100 times in consideration of cleaning efficiency. The water for dilution may be the same as the above-mentioned polishing composition.

  According to the substrate manufacturing method of the present invention, it is possible to efficiently manufacture a substrate in which the alumina piercing on the substrate after the rough polishing step and the protrusions and dent defects on the substrate after the finish polishing step are effectively reduced. Therefore, it can be suitably used for polishing a magnetic disk substrate of a perpendicular magnetic recording system that requires a high degree of surface smoothness.

[Polishing method]
In another aspect, the present invention includes the following steps (1) to (5), the following steps (1) to (3) are performed by the same polishing machine, and the following step (5) is performed by the polishing machine. The present invention relates to a method for polishing a magnetic disk substrate performed by a different polishing machine.
(1) A polishing composition A containing alumina particles and water is supplied to a surface to be polished of a substrate to be polished, a polishing pad is brought into contact with the surface to be polished, and the polishing pad and / or the substrate to be polished is moved. Polishing the surface to be polished, (2) rinsing the substrate obtained in step (1), (3) obtaining a polishing composition B containing silica particles and water in step (2). (4) Step (3): supplying to the surface to be polished of the prepared substrate, bringing a polishing pad into contact with the surface to be polished, and moving the polishing pad and / or the substrate to be polished to polish the surface to be polished; And (5) supplying the polishing composition C containing silica particles and water to the surface to be polished of the substrate obtained in step (4), and polishing the surface to be polished. Contacting the pad, the polishing pad and / or the Polishing the polished surface by moving the polishing substrate.

  In addition, about the to-be-polished substrate, polishing pad, the composition of polishing liquid compositions A to C, the rinsing method, the cleaning agent composition, and the polishing method and conditions in the polishing method of the present invention, the substrate of the present invention described above is used. It can be the same as the manufacturing method.

  According to the polishing method of the present invention, it is possible to efficiently manufacture a substrate in which the alumina piercing on the substrate after the rough polishing step and the protrusions and dent defects on the substrate after the final polishing step are effectively reduced. An effect that a magnetic disk substrate with improved quality can be manufactured with high productivity can be achieved.

  By using the polishing method of the present invention, the quality of the magnetic disk substrate, particularly the vertical, is improved by reducing alumina stabs on the substrate after the rough polishing step and protrusions and dent defects on the substrate after the final polishing step. A magnetic recording type magnetic disk substrate is preferably provided. Examples of the substrate to be polished in the polishing method of the present invention include those used in the manufacture of a magnetic disk substrate and a magnetic recording medium substrate as described above. A substrate used for production is preferred.

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

  Polishing liquid composition A, B, and C was prepared as follows, and the to-be-polished substrate containing process (1)-(5) was grind | polished on the following conditions. 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 compositions A to C
[Preparation of Polishing Liquid Composition A]
A polishing composition A was prepared using the alumina abrasive grains A, citric acid, sulfuric acid, hydrogen peroxide, water shown in Table 1 below, and, in some cases, additive A or B shown in Table 3 below (Table 4 below). ). The content of each component in the polishing composition A is 4.0% by mass of alumina particles, 0.5% by mass of citric acid, 0.5% by mass of sulfuric acid, and 0.5% by mass of hydrogen peroxide. The pH of the polishing composition A was 1.4. The contents of Additives A and B were 0.05% by mass.

[Preparation of polishing liquid composition B]
Polishing liquid composition B was prepared using the colloidal silica abrasive grain a shown in Table 2 below, sulfuric acid, phosphoric acid, hydrogen peroxide, and water (Table 4 below). The content of each component in the polishing liquid composition B is as follows: silica particles: 5.0 mass%, sulfuric acid: 0.4 mass%, phosphoric acid: 1.5 mass%, hydrogen peroxide: 0.5 mass% Yes, the pH of the polishing composition B was 1.6. Additives C, D, E, and F were 0.02% by mass, and additive G was 0.1% by mass.

[Preparation of polishing liquid composition C]
Colloidal silica abrasive grains b shown in Table 2 below, sulfuric acid, phosphoric acid, 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), hydrogen peroxide, water and optionally additives C to G in Table 3 below. A polishing liquid composition C was prepared. The content of each component in the polishing composition C was as follows: silica particles b: 5.58% by mass, sulfuric acid: 0.6% by mass, phosphoric acid: 0.81% by mass, 1-hydroxyethylidene-1,1-diphosphone The acid (HEDP) was 0.2% by mass, the hydrogen peroxide was 0.6% by mass, and the pH of the polishing composition C was 1.5.

[Measurement of average secondary particle diameter of alumina particles]
A 0.5% poise 530 (manufactured by Kao Corporation; special polycarboxylic acid type polymer surfactant) aqueous solution is used as a dispersion medium, and it is put into the following measuring apparatus, and then a sample is obtained so that the transmittance is 75 to 95%. After that, after applying ultrasonic waves for 5 minutes, the particle size was measured.
Measuring equipment: Laser diffraction / scattering type particle size distribution measuring instrument LA920 manufactured by HORIBA, Ltd.
Circulation strength: 4
Ultrasonic intensity: 4

[Measurement method of alpha conversion rate of alumina]
20 g of alumina slurry was dried at 105 ° C. for 5 hours, and the resulting dried product was crushed with a mortar to obtain a powder X-ray diffraction sample. Each sample was analyzed by the powder X-ray diffraction method, and the peak areas on the 104th surface were compared. The measurement conditions by the powder X-ray diffraction method were as follows.
Measurement condition;
Apparatus: Rigaku Co., Ltd., powder X-ray analyzer RINT2500VC
X-ray generation voltage: 40 kV
Radiation: Cu-Kα1 line (λ = 0.154050 nm)
Current: 120 mA
Scan Speed: 10 degrees / minute Measurement step: 0.02 degrees / minute pregelatinization rate (%) = alpha area peculiar to alumina / peak area of WA-1000 × 100
The area of each peak was calculated from the obtained powder X-ray diffraction spectrum using the powder X-ray diffraction pattern comprehensive analysis software JADE (MDI) attached to the powder X-ray diffractometer. The calculation process by the software was calculated based on the instruction manual of the software (Jade (Ver. 5) software, instruction manual Manual No. MJ13133E02, Rigaku Corporation). WA-1000 is α-alumina (manufactured by Showa Denko KK) having an α conversion rate of 99.9%.

[Measurement of average primary particle diameter of silica particles and standard deviation of primary particle diameter]
Photos of silica particles observed with a transmission electron microscope (TEM) manufactured by JEOL (trade name “JEM-2000FX”, 80 kV, 1 to 50,000 times) are captured as image data with a scanner on a personal computer, and analysis software “WinROOF (Ver .3.6) ”(distributor: Mitani Shoji Co., Ltd.), obtain the equivalent circle diameter of each silica particle from 1000 to 2000 or more silica particle data and use it as the diameter to calculate the spreadsheet software“ EXCEL ”( The standard deviation of the volume-based particle size (sample standard deviation) was obtained by Microsoft). In addition, based on the particle size distribution data of silica particles obtained by converting the particle diameter to the particle volume with the spreadsheet software “EXCEL”, the ratio of particles having a certain particle size in all particles (volume basis%) Was expressed as the cumulative frequency from the small particle size side, and the cumulative volume frequency (%) was obtained. By plotting the cumulative volume frequency against the particle diameter based on the particle diameter and cumulative volume frequency data of the obtained silica particles, a particle diameter versus cumulative volume frequency graph is obtained. In the graph, the particle diameter at which the cumulative volume frequency from the small particle diameter side becomes 50% was defined as the average primary particle diameter (D50) of the silica particles. Further, the particle diameter at which the cumulative volume frequency from the small particle diameter side is 10% is defined as the primary particle diameter (D10) of the silica particles, and the particle diameter at which the cumulative volume frequency from the small particle diameter side is 90% is The primary particle size (D90) was used.

[Measurement of weight average molecular weight]
The weight average molecular weight (Mw) of the anionic polymer was measured by gel permeation chromatography (GPC) using a high performance liquid chromatograph under the following conditions. A calibration curve was determined using a molecular weight standard sample, and the weight average molecular weight (Mw) of the polymer was determined based on the calibration curve.

[GPC conditions]
1. Additive A measurement / measurement device: HLC-8220GPC (manufactured by Tosoh Corporation)
Column: TSKgel G4000PWXL + TSKgel G2500PWXL (manufactured by Tosoh Corporation)
Eluent: 0.2M phosphate buffer / CH ₃ CN = 9/1 volume ratio Temperature: 40 ° C.
・ Flow rate: 1.0 mL / min
・ Sample size: 5mg / mL
・ Injection volume: 100 μL
・ Detector: RI (manufactured by Tosoh Corporation)
Conversion standard: Polyacrylic acid Na (molecular weight standard sample)
2. Additives C, E, F measurement / measurement device: HLC-8220GPC (manufactured by Tosoh Corporation)
Column: TSKgel G4000PWXL + TSKgel G2500PWXL (manufactured by Tosoh Corporation)
Eluent: 0.2M phosphate buffer / CH ₃ CN = 9/1 volume ratio Temperature: 40 ° C.
・ Flow rate: 1.0 mL / min
・ Sample size: 1 mg / mL
-Injection volume: 10 μL
・ Detector: UV210nm (manufactured by Tosoh Corporation)
Conversion standard: Polystyrene sulfonate Na (molecular weight standard sample)
3. Additive D measurement / measurement device: HLC-8320GPC (manufactured by Tosoh Corporation)
Column: TSKgel α-M + α-M (anion) (manufactured by Tosoh Corporation)
Eluent: 60 mmol / LH ₃ PO ₄ , 50 mmol / LLiBr / DMF
・ Temperature: 40 ℃
・ Flow rate: 1.0 mL / min
・ Sample size: 1 mg / mL
・ Injection volume: 100 μL
・ Detector: UV210nm (manufactured by Tosoh Corporation)
・ Conversion standard: Polystyrene (molecular weight standard sample)

[Polished substrate]
The substrate to be polished was an aluminum alloy substrate plated with Ni-P. The substrate to be polished had a thickness of 1.27 mm and a diameter of 95 mm (a perforated donut shape with a central part diameter of 25 mm).

[Polishing the substrate to be polished]
The substrate to be polished including steps (1) to (5) was polished. The conditions for each step are shown below. In addition, process (1)-(3) was performed with the same grinding machine, and process (5) was performed with the grinding machine separate from the said grinding machine.

[Step (1): First rough polishing]
Polishing machine: Double-side polishing machine (9B-type double-side polishing machine, manufactured by Speed Fam Co., Ltd.)
Polishing pad: Suede type (foam layer: polyurethane elastomer), thickness 1.04mm, average pore diameter 43μm (FILWEL)
Plate rotation speed: 45rpm
Polishing load: 9.8 kPa (set value)
Polishing liquid supply amount: 100 mL / min (0.076 mL / (cm ² · min)) for 3 minutes Polishing amount: 1.0 to 1.2 mg / cm ²
Number of substrates loaded: 10 (double-side polishing)

[Step (2): Intermediate rinse]
Rinse conditions:
-Polishing machine and polishing pad: Same as in step (1)-Surface plate rotation speed: 45 rpm
・ Polishing load: 9.8 kPa (set value)
・ Ion-exchanged water supply amount: 2 L / min (1.52 mL / (cm ² · min) for 10 seconds

[Step (3): Second rough polishing]
Polishing machine and polishing pad: Same platen rotation speed as in step (1): 45 rpm
Polishing load: 9.8 kPa (set value)
Polishing liquid supply amount: 100 mL / min (0.076 mL / (cm ² · min)) for 1 minute Polishing amount: 0.02 to 0.04 mg / cm ²
Step (3) includes a rinsing step under the following conditions after polishing under the above conditions.
Rinse conditions:
・ Surface plate speed: 20rpm
・ Polishing load: 1.4 kPa
・ Ion-exchanged water supply amount: 2 L / min (1.52 mL / (cm ² · min) for 15 seconds

[Step (4): Washing]
The substrate obtained in the step (3) was washed under the following conditions.
1. The substrate obtained in the step (3) is immersed for 5 minutes in a 25 ° C. bath containing an alkaline detergent composition having a pH of 12 consisting of a 0.1% by mass aqueous KOH solution.
2. The substrate after immersion is rinsed with ion exchange water for 20 seconds.
3. The rinsed substrate is transferred to a scrub cleaning unit in which a cleaning brush is set and cleaned.

[Step (5): Final polishing]
Polishing machine: Double-side polishing machine (9B type double-side polishing machine, manufactured by Speedfam), polishing machine separate from the polishing machine used in steps (1) to (3): Suede type (foamed layer: polyurethane elastomer) , Thickness 1.0mm, average pore diameter 5μm (FILWEL)
Plate rotation speed: 40 rpm
Polishing load: 9.8 kPa (set value)
Polishing liquid supply amount: 100 mL / min for 3 minutes Polishing amount: 0.2 to 0.3 mg / cm ²
Number of substrates loaded: 10 (double-side polishing)
After the step (5), rinsing and washing were performed. The rinsing conditions were the same as those in the step (3), and the cleaning conditions were the same as those in the step (4).

[Measurement method of polishing rate]
The weight of each substrate before and after polishing (before step (1) and after step (3)) in the rough polishing step (entire step (1) to step (3)) is a weigh scale ("BP-210S" manufactured by Sartorius). )), The change in the weight of each substrate was determined, the average value of the 10 sheets was taken as the weight reduction amount, and the value obtained by dividing that by the polishing time was taken as the weight reduction rate. This weight reduction rate was introduced into the following formula and converted into a polishing rate (μm / min) (average polishing rate of the entire process (1) to process (3)). The results are shown in Table 4 below as relative values with Comparative Example 1 taken as 100. In addition, it can be said that it is at the level which can fully grind | polish when the relative value is 70 or more, and can maintain polishing speed.
Polishing rate (μm / min) = weight reduction rate (g / min) / substrate single-sided area (mm ² ) / Ni-P plating density (g / cm ³ ) × 10 ⁶
(Substrate single-sided area: 6597 mm ² , Ni—P plating density: calculated as 7.9 g / cm ³ )

[Method of evaluating alumina sticking after washing step (4)]
Measuring instrument: OSA7100 (manufactured by KLA Tencor)
Evaluation: Polishing liquid composition C (colloidal silica abrasive grain a) under the same conditions as in step (5) except that the substrate obtained in the cleaning step (4) was polished to 0.002 mg / cm ^2. Then, rinsing and washing were performed, and then 4 pieces were selected at random, and each substrate was irradiated with a laser at 10,000 rpm to measure the number of alumina sticks. The total number of alumina sticks (pieces) on both surfaces of each of the four substrates was divided by 8 to calculate the number of alumina sticks (pieces) per board surface. The results are shown in Table 4 below as relative values with Comparative Example 1 taken as 100. The rinse conditions were the same as those in the step (3), and the cleaning conditions were the same as those in the step (4).

[Evaluation method of number of protrusions and dent defects after finishing step (5)]
Measuring instrument: OSA7100 (manufactured by KLA Tencor)
Evaluation: After finishing step (5), out of the substrates subjected to scrub cleaning under the same conditions as in step (4), four are selected at random, and each substrate is irradiated with a laser at 8000 rpm to make a protrusion. And the number of dent defects was measured. The total number of protrusions and dent defects (pieces) on each of the four substrates was divided by 8 to calculate the number of protrusions and dent defects per substrate surface. The results are shown in Table 4 below as relative values with Comparative Example 1 taken as 100.

  As shown in Table 4, in Examples 1 to 8 containing an anionic polymer in the polishing liquid composition C, there was less alumina piercing after the step (4) (after completion of rough polishing) compared to Comparative Examples 1 to 4. It was shown that the number of protrusions and dent defects after step (5) (after finishing polishing) was reduced. Further, as shown in Comparative Examples 1 to 10, if any of the additives of the polishing liquid composition C in the intermediate rinsing process (2) and the final polishing process (5) is missing, after the process (4) (rough polishing ends) It was shown that the number of protrusions and dent defects after (after) alumina piercing and / or step (5) (after finishing polishing) could not be significantly reduced.

  The method for producing a magnetic disk substrate of the present invention can be suitably used for producing a magnetic disk substrate having a high recording density, for example.

Claims (8)

The following steps (1) to (5) are performed, the following steps (1) to (3) are performed by the same polishing machine, and the following step (5) is performed by a polishing machine different from the polishing machine. A manufacturing method of a disk substrate.
(1) A polishing composition A containing alumina particles and water is supplied to a surface to be polished of a substrate to be polished, a polishing pad is brought into contact with the surface to be polished, and the polishing pad and / or the substrate to be polished is moved. Polishing the surface to be polished,
(2) A step of rinsing the substrate obtained in step (1),
(3) A polishing liquid composition B containing silica particles and water is supplied to the polishing target surface of the substrate obtained in step (2), and the polishing pad is brought into contact with the polishing target surface, and the polishing pad and / or Moving the substrate to be polished to polish the surface to be polished;
(4) A step of cleaning the substrate obtained in step (3),
(5) The polishing liquid composition C containing colloidal silica particles having an average primary particle diameter of 5 to 100 nm, an inorganic acid or a salt thereof, an organic phosphonic acid-based chelating agent, and water is obtained from the substrate obtained in step (4). Supplying the polishing target surface, bringing the polishing pad into contact with the polishing target surface, and moving the polishing pad and / or the substrate to be polished to polish the polishing target surface;   The organic phosphonic acid-based chelating agent includes 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), phosphonobutanetricarboxylic acid (PBTC), aminotrismethylenephosphonic acid (NTMP), hexamethylenediaminetetramethylenephosphonic acid, and The method of manufacturing a magnetic disk substrate according to claim 1, wherein the method is selected from the group consisting of these salts.   The method for producing a magnetic disk substrate according to claim 1, wherein the polishing liquid composition C further contains a sulfonic acid (group) salt and an anionic polymer having an aromatic group in the main chain.   The anionic polymer is naphthalene sulfonic acid formaldehyde condensate, methyl naphthalene sulfonic acid formaldehyde condensate, anthracene sulfonic acid formaldehyde, melamine sulfonic acid formaldehyde condensate, lignin sulfonic acid, modified lignin sulfonic acid, aminoaryl sulfonic acid-phenol- 4. The method of manufacturing a magnetic disk substrate according to claim 3, wherein the magnetic disk substrate is selected from the group consisting of formaldehyde condensates and salts thereof.   5. The magnetic disk substrate according to claim 1, wherein the polishing liquid composition C further contains at least one selected from the group consisting of glycerin, ethylene glycol, diethylene glycol, triethylene glycol, and propylene glycol. Manufacturing method. The polishing composition A further comprises:
The polyacrylic acid having a molecular weight of 300 to 300,000 and a salt thereof, and (ii) at least one selected from the group consisting of a polyoxyethylene alkyl ether phosphoric acid and a salt thereof. A method of manufacturing a magnetic disk substrate.   The method for manufacturing a magnetic disk substrate according to claim 1, wherein the substrate to be polished is a Ni—P plated aluminum alloy substrate. The following steps (1) to (5) are performed, the following steps (1) to (3) are performed by the same polishing machine, and the following step (5) is performed by a polishing machine different from the polishing machine. A method for polishing a disk substrate.
(1) A polishing composition A containing alumina particles and water is supplied to a surface to be polished of a substrate to be polished, a polishing pad is brought into contact with the surface to be polished, and the polishing pad and / or the substrate to be polished is moved. Polishing the surface to be polished,
(2) A step of rinsing the substrate obtained in step (1),
(3) A polishing liquid composition B containing silica particles and water is supplied to the polishing target surface of the substrate obtained in step (2), and the polishing pad is brought into contact with the polishing target surface, and the polishing pad and / or Moving the substrate to be polished to polish the surface to be polished;
(4) A step of cleaning the substrate obtained in step (3),
(5) Polishing a substrate obtained by the step (4) using a polishing composition C containing colloidal silica particles having an average primary particle size of 5 to 100 nm, an inorganic acid or a salt thereof, an organic phosphonic acid chelating agent and water. Supplying to a target surface, bringing a polishing pad into contact with the target surface and moving the polishing pad and / or the substrate to be polished to polish the target surface;