JP6480139B2 - Polishing composition - Google Patents

Description

  The present invention relates to a polishing composition.

  Heretofore, the process of manufacturing a substrate requiring a highly accurate surface often includes the step of polishing an object to be polished, which is a raw material of the substrate, using a polishing liquid. For example, in the manufacture of a nickel phosphorous plated disk substrate (Ni-P substrate), in general, more polishing efficiency is required before the final polishing step (finish polishing step) performed to finish the surface accuracy of the final product. Polishing (primary polishing) that emphasizes is performed. In such a polishing process, for example, as in the above-mentioned primary polishing, it is important to realize a good surface condition because it contributes to the improvement of the surface accuracy in the final polishing step even in the polishing performed before the final polishing step. It is. Patent documents 1 to 4 can be mentioned as technical documents related to polishing of a magnetic disk substrate.

JP 2005-63530 A JP, 2014-130663, A JP, 2014-29754, A JP, 2014-29755, A

In the technique described in Patent Document 1, alumina abrasives are used as the abrasives in the primary polishing. However, while alumina abrasives are excellent in polishing efficiency, surface defects such as scratches and pits increase, or defects such as part of abrasive particles stick to the substrate and remain until after the final polishing step. There was a risk of contributing to this.
Moreover, patent documents 2-4 relate to the technique which uses a silica abrasive as an abrasive in the said primary grinding | polishing. However, silica abrasives tend to be inferior in polishing efficiency (typically, polishing rate) to polishing compositions containing alumina abrasives, and have high polishing rates, such as primary polishing of Ni-P substrates, for example. When used in the required polishing, there is a risk that such a request can not be sufficiently met.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a polishing composition which can exhibit a higher polishing rate using silica abrasive grains.

  According to the present invention, there is provided a polishing composition comprising an abrasive, an acid and water. Here, the abrasive grains include silica abrasive grains A. The said silica abrasive grain A is baked. According to the polishing composition containing such silica abrasive grains A, a high polishing rate can be achieved.

  According to another preferred embodiment of the polishing composition disclosed herein, the silica abrasive grain A is fired at a firing temperature of 600 ° C. or more and 1100 ° C. or less. According to the polishing composition containing the silica abrasive grains A, it is possible to exert a high polishing rate and to achieve a practically sufficient surface accuracy on the surface to be polished.

  According to another preferred embodiment of the polishing composition disclosed herein, the silica abrasive grain A is further crushed after being fired. According to the polishing composition containing such silica abrasive grains A, a higher polishing rate can be exhibited, and higher surface accuracy can be realized on the surface to be polished.

  According to another preferred embodiment of the polishing composition disclosed herein, the polishing composition further contains an oxidizing agent. Such a polishing composition may exhibit a more excellent polishing rate.

  Any of the polishing compositions disclosed herein is suitable as a polishing composition to be used in the process prior to the final polishing process. Typically, the above polishing composition can be suitably used for temporary polishing of an object to be polished. For example, the polishing composition can be suitably used for primary polishing of a nickel phosphorus plated disk substrate (Ni-P substrate) or a magnetic disk substrate.

  A preferred application of any of the polishing compositions disclosed herein is a nickel phosphorous plated disk substrate (Ni-P substrate). The Ni-P substrate may be a magnetic disk substrate. When the polishing composition is applied to the Ni-P substrate, a high polishing rate can be achieved, and the surface accuracy of the Ni-P substrate after polishing can be at a practically sufficient level. The polishing composition disclosed herein is particularly suitable for primary polishing of a Ni-P substrate.

  According to the present invention, there is also provided a polishing composition comprising abrasive grains containing silica abrasive grains A, an acid and water, wherein the silica abrasive grains A are crushed. According to the polishing composition containing such silica abrasive grains A, a high polishing rate can be realized, and further, more excellent surface accuracy can be realized on the surface to be polished.

  According to the technology disclosed herein, a method of manufacturing a polishing composition is provided. The production method includes preparing silica abrasive grain A by applying at least one of calcination and crushing to silica, which is a raw material, and mixing abrasive grains containing silica abrasive grain A, acid and water. . According to the above manufacturing method, a polishing composition capable of realizing a high polishing rate can be provided.

According to the technology disclosed herein, a method of manufacturing a substrate is provided. The manufacturing method includes a polishing step A in which any polishing composition disclosed herein is supplied to a polishing object which is a raw material of the substrate to polish the polishing object. According to this manufacturing method, a substrate having a stable, high-quality surface can be manufactured with high productivity.
The manufacturing method may further include a finishing polishing step of supplying a polishing composition including colloidal silica abrasive particles to the polishing object after the polishing step A to polish the polishing object. According to this manufacturing method, a substrate having a higher quality surface can be manufactured with high productivity.

  Hereinafter, preferred embodiments of the present invention will be described. The matters other than the matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be understood as the design matters of those skilled in the art based on the prior art in the relevant field. The present invention can be implemented based on the contents disclosed in the present specification and common technical knowledge in the field.

  The polishing composition disclosed herein comprises an abrasive. The abrasive has a function of mechanically polishing the surface of the object to be polished (typically, a magnetic disk substrate). The inventors of the present invention have been able to achieve a higher polishing rate according to the polishing composition including, as the abrasive, the silica abrasive A comprising silica particles to which at least one of calcination and crushing has been applied. I found it.

<Silica abrasive grain A>
The silica abrasive grain A in the art disclosed herein is composed of silica particles mainly composed of silica. Specific examples of the silica abrasive particles A disclosed herein include precipitated silica, gel-method silica, colloidal silica, fumed silica, dry silica, and explosive silica. Alternatively, the above-mentioned silica abrasive grains A may be abrasive grains made of precipitated silica, gel silica, colloidal silica, fumed silica, dry silica, explosive silica, etc. As the silica abrasive grain A, one of the above-mentioned silicas may be used, or two or more thereof may be used in combination. In the technology disclosed herein, it is preferable to use precipitated silica, gel method silica, fumed silica, or silica particles using these silica as raw materials, and precipitated silica, gel method silica, or these silicas as raw materials It is more preferable to use the prepared silica particles. Such silica abrasive grains A can contribute to the improvement of the polishing rate.

  The average particle size of silica (hereinafter, also referred to as raw material silica) as a raw material of the silica abrasive grains A is not particularly limited. The average particle size of the raw material silica is typically 500 nm or more and 30000 nm or less, preferably 1000 nm or more and 20000 nm or less. The preferred average particle size of the raw material silica also depends on the type of raw material silica. For example, when the raw material silica is gel method silica, it is appropriate that the average particle size of the raw material silica is usually 500 nm or more and 10000 nm or less, preferably 1000 nm or more and 8000 nm or less, more preferably 2000 nm More than 6000 nm. When the raw material silica is precipitated silica, the average particle size of the raw material silica is usually 1000 nm to 30000 nm, preferably 5000 nm to 25000 nm, and more preferably 10000 nm to 20000 nm. It is. According to the raw material silica in which the average particle size is in the above-mentioned range, the silica abrasive grains A capable of exhibiting high polishing power tend to be prepared by calcination and / or crushing described later.

  In the present specification, unless otherwise specified, the average particle size refers to a volume-based average particle size (50% volume average particle size) based on a laser diffraction / scattering method. The measurement of the average particle diameter can be performed, for example, using a laser diffraction / scattering particle size distribution measuring device (model “LA-950”, manufactured by Horiba, Ltd.).

The specific surface area of the raw material silica is not particularly limited. The specific surface area of raw material silica is typically 5 m ² / g or more and 800 m ² / g or less, preferably 10 m ² / g or more and 500 m ² / g or less, more preferably 15 m ² / g or more and 300 m ² / g or less It is. The preferred specific surface area of the raw material silica can also depend on the type of raw material silica. For example, when the raw material silica is gel method silica, the specific surface area of the raw material silica is usually 10 m ² / g or more and 700 m ² / g or less, preferably 20 m ² / g or more and 500 m or more ^{It is 2} / g or less, more preferably 30 m ² / g or more and 400 m ² / g or less. For example, when the raw material silica is precipitated silica, the specific surface area of the raw material silica is typically 5 m ² / g or more and 300 m ² / g or less, preferably 10 m ² / g or more and 100 m ² / g or less And more preferably 15 m ² / g or more and 40 m ² / g or less. According to the raw material silica having a specific surface area in the range described above, there is a tendency that the silica abrasive grains A capable of exerting high polishing power tend to be prepared by calcination and / or crushing described later.

  Here, in the present specification, a specific surface area measured by the BET method can be employed as the specific surface area. The measurement of the specific surface area can be performed, for example, using a surface area measurement device manufactured by Micromeritex, trade name "Flow Sorb II 2300".

  It is preferable that the silica abrasive grain A indicated here is what was baked on predetermined | prescribed conditions (henceforth a calcination silica). In other words, the silica abrasive grain A can be suitably prepared by firing the raw material silica (raw material silica). The polishing composition containing such silica abrasive grains A tends to exhibit a high polishing rate.

  The calcination temperature at the time of the said calcination should just be lower than the melting point of the silica abrasive grain A, and is not specifically limited. The firing temperature is preferably 1200 ° C. or less, more preferably 1100 ° C. or less (e.g., 1000 ° C. or less), from the viewpoint of suppressing excessive growth of the fired silica. The above-mentioned firing temperature is usually 500 ° C. or higher, preferably 600 ° C. or higher, more preferably 750 ° C. or higher, and still more preferably 850 ° C. or higher (eg, 950 ° C. or higher). According to the silica abrasive grain A fired at the firing temperature in the above-described range, a high polishing rate can be realized, and further, practically sufficiently excellent surface accuracy can be achieved on the surface to be polished.

  The time for firing the raw material silica is not particularly limited. The baking time may be, for example, about 30 minutes to 10 hours, preferably about 1 hour to 5 hours. If the firing time is shorter than 30 minutes, the fired silica is not sufficiently compacted, and according to the polishing composition containing such fired silica as the silica abrasive grain A, the polishing rate is difficult to improve. In addition, it is not preferable from the economical point of view if the firing time is longer than 10 hours.

  The atmosphere for firing the raw material silica is not particularly limited. The firing atmosphere may be, for example, an inert gas, a reducing gas, an oxidizing gas (such as air), and the like. Also, the raw material silica may be fired in a substantially vacuum state.

The specific surface area of the above-mentioned calcined silica is not particularly limited. The specific surface area of the calcined silica is 5 m ² / g or more and 500 m ² / g or less, preferably 10 m ² / g or more and 100 m ² / g or less. The preferred specific surface area of the pyrogenic silica can also depend on the type of raw material silica. For example, when the raw material silica is a gel method silica, the specific surface area of the calcined silica is usually 5 m ² / g or more and 500 m ² / g or less, preferably 8 m ² / g or more and 300 m ² or more. / G or less, more preferably 10 m ² / g or more and 100 m ² / g or less. For example, when the raw material silica is precipitated silica, the specific surface area of the pyrogenic silica is typically 5 m ² / g or more and 200 m ² / g or less, preferably 8 m ² / g or more and 50 m ² / g or less is there. When the calcined silica having a specific surface area in the range described above is used as the silica abrasive grain A, a high polishing rate tends to be realized. In addition, there is a tendency that silica abrasive grains A capable of exhibiting higher polishing power are prepared by crushing such calcined silica as described later.

  In the art disclosed herein, it is preferable that the silica abrasive grains A be crushed. More preferably, the above-mentioned silica abrasive grain A is further crushed after being fired. Here, the term "crushing" as used herein refers to an operation of loosening and chopping fine particles into which they are collected. The above-mentioned crushing tends to reduce the average particle size of the silica particles.

  The crushing method is not particularly limited as long as a known method conventionally used conventionally in this type of field is used. For example, the above-mentioned crushing can be carried out using a crusher such as a bead mill, ball mill, roller mill, hammer mill, jet mill, mortar and the like (the crusher can also be recognized as a crusher). Among them, crushing with a bead mill, a ball mill or a jet mill is preferable from the viewpoint of obtaining a silica abrasive A having a suitable average particle diameter and a specific surface area. The polishing composition containing the silica abrasive particles A crushed in this manner has an effect of improving the surface accuracy of the surface to be polished (for example, the effect of suppressing long wavelength waviness, surface roughness, and the like) while realizing a high polishing rate. There is a tendency to exhibit the effect of reducing the height etc. suitably.

  In the technology disclosed herein, the average particle size of the silica before being crushed (hereinafter also referred to as silica before crushing; typically, the silica before crushing is calcined silica) is usually The thickness is suitably 1000 nm or more and 30000 nm or less, preferably 2000 nm or more and 25000 nm or less, and more preferably 3000 nm or more and 20000 nm or less. The average particle size of the crushed silica (hereinafter, also referred to as crushed silica, typically the crushed silica is the silica abrasive grain A) is typically 50 nm or more and 3000 nm or less, and preferably Is 100 nm or more and 1500 nm or less, more preferably 150 nm or more and 1000 nm or less. When the crushing process is performed using the pre-crushing silica having an average particle size in the range described above, a crushed silica having a suitable average particle size as described above is easily obtained. When such crushed silica is used as the silica abrasive grain A, there is a tendency to obtain a polishing composition which can realize both a more excellent polishing rate and an excellent surface accuracy on the surface to be polished.

In the art disclosed herein, the specific surface area of the silica abrasive grains A is preferably 2 m ² / g or more. From the viewpoint of reducing the long wavelength waviness of the surface to be polished or reducing the surface roughness of the surface, the specific surface area of the silica abrasive grain A is more preferably 10 m ² / g or more, still more preferably 12 m ² / g or more (e.g., 15 m ² / g or more). Also, from the viewpoint of improving the polishing rate, the specific surface area of the above-mentioned silica abrasive grain A is preferably 60 m ² / g or less, more preferably 50 m ² / g or less, still more preferably 45 m ² / g or less (typical) And 30 m ² / g or less, for example, 28 m ² / g or less). According to the polishing composition containing the silica abrasive grain A in which the specific surface area is in the range described above, the improvement of the polishing rate and the excellent surface accuracy of the surface to be polished can be achieved simultaneously.
For example, according to one preferred embodiment of the polishing compositions disclosed herein, specific surface area of the silica abrasive A is, ^{10 m} 2 / g or more ^{60 m} 2 / g or less (more preferably ^12m 2 / g or more ^{50 m} 2 / It is g or less, more preferably 15 m ² / g or more and 45 m ² / g or less. According to the polishing composition containing such silica abrasive grains A, a higher polishing rate can be realized, and further, higher surface accuracy can be achieved on the surface to be polished.

In the art disclosed herein, the average particle diameter of the silica abrasive grains A is preferably 50 nm or more, more preferably 100 nm or more, and still more preferably 150 nm or more, from the viewpoint of improving the polishing rate. The average particle diameter of the silica abrasive grains A is preferably 15000 nm or less, more preferably 13000 nm or less, and still more preferably 7000 nm or less, from the viewpoint of suppressing the decrease in polishing rate due to the aggregation of the abrasive grains.
For example, according to a preferred embodiment of the polishing composition disclosed herein, the average particle diameter of the silica abrasive grains A is 100 nm to 5000 nm (more preferably 120 nm to 1000 nm, still more preferably 130 nm to 700 nm). For example, 150 nm or more and 600 nm or less). According to the polishing composition containing the silica abrasive grain A having such an average particle diameter, high polishing rate and excellent surface accuracy of the surface to be polished (for example, reduction of surface long wavelength waviness or reduction of surface roughness) are obtained. It is easy to achieve both at a high level.
In addition, according to another preferable embodiment of the polishing composition disclosed herein, the average particle diameter of the silica abrasive grain A is 2000 nm or more and 10000 nm or less (more preferably 3000 nm or more and 7000 nm or less). A polishing composition containing silica abrasives A having such an average particle size tends to exhibit a high polishing rate.

  In the polishing composition disclosed herein, the content of the above-mentioned silica abrasive grains A in the solid content contained in the polishing composition is not particularly limited. The content of the above-mentioned silica abrasive grains A is preferably 10% by weight or more, more preferably 20% by weight or more, still more preferably 30% by weight from the viewpoint of facilitating the effects of the present invention. % Or more (for example, 40% by weight or more). Moreover, the upper limit of content of the said silica abrasive grain A is not specifically limited. The silica abrasive grains A may be substantially all solid content contained in the polishing composition. Alternatively, the content of the above-mentioned silica abrasive grains A is 90% by weight or less of the total solid content from the viewpoint of balancing various performances (for example, polishing rate, surface roughness after polishing of the surface to be polished, etc.) Is more preferably 80% by weight or less, still more preferably 70% by weight or less (eg 60% by weight or less).

<Abrasive grain B>
The polishing composition disclosed herein contains another component (hereinafter also referred to as an abrasive B) different from the silica abrasive A as an abrasive within a range not impairing the effects of the present invention. Good. Examples of the abrasive grains B include particles made of materials other than silica (hereinafter also referred to as non-silica particles) and silica particles different from the silica abrasive particles A. These can be used singly or in combination of two or more.

Examples of non-silica particles include inorganic particles, organic particles, and organic-inorganic composite particles. Examples of the inorganic particles include alumina particles (α-alumina, intermediate alumina other than α-alumina, and composites thereof. Intermediate alumina is a generic name of alumina particles other than α-alumina, and specifically Are, for example, γ-alumina, δ-alumina, θ-alumina, ア ル ミ ナ -alumina, κ-alumina and composites thereof), cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, oxide Oxide particles such as magnesium particles, manganese dioxide particles, zinc oxide particles, and Bengala particles; nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; Carbonates such as barium carbonate and the like can be mentioned. Moreover, as a specific example of the organic particles, polymethyl methacrylate (PMMA) particles and poly (meth) acrylic acid particles (herein, (meth) acrylic acid has a meaning comprehensively indicating acrylic acid and methacrylic acid) And polyacrylonitrile particles. As the organic-inorganic composite particles, particles in which the surface of the inorganic particles is modified by an organic compound, particles in which the inorganic particles are attached to the surface of the organic particles (including rubber particles), particles made of an organic-inorganic composite material It can be mentioned.
As non-silica particles, particles having a hardness lower than that of α-alumina particles are suitable. Examples of such non-silica particles include resin particles such as intermediate alumina, titania particles, and polyacrylic acid.
As a silica particle different from the silica abrasive grain A, the silica particle which is not baked, the silica particle which is not crushed, the silica particle which is neither baked nor crushed is mentioned. Specifically, for example, colloidal silica can be used as the silica particles other than the silica abrasive grains A.

  The average particle size (50% volume average particle size) of the abrasive grains B is not particularly limited. The average particle size of the abrasive grains B is typically 5 nm or more, usually more than 20 nm, preferably more than 30 nm, more preferably more than 50 nm, still more preferably more than 60 nm. Higher polishing rates can be achieved by the increase of the average particle size. The upper limit of the average particle size of the abrasive grains B is not particularly limited, and may be, for example, 1 μm or less. From the viewpoint of dispersion stability and the like, the average particle size of the abrasive grains B is usually 500 nm or less, preferably 300 nm or less, more preferably 200 nm or less, and still more preferably 150 nm or less.

  Although not particularly limited, as the abrasive grains B, those having an average particle size equal to or less than the average particle size of the silica abrasive grains A, for example, 1.1 times or less of the average particle size of the silica abrasive grains A are suitable It can be used for The average particle diameter of the abrasive particles B is preferably less than 1.0 times and not more than 0.7 times the average particle diameter of the silica abrasive particles A from the viewpoint of exerting the polishing action by the silica abrasive particles A better. It is more preferable that The average particle size of the abrasive grains B may be 0.5 times or less, further 0.3 times or less of the average particle size of the silica abrasive grains A.

The specific surface area of the abrasive grains B is not particularly limited. The specific surface area of the abrasive grain B is typically 1 m ² / g or more, usually 2 m ² / g or more, preferably 5 m ² / g or more, more preferably 10 m ² / g or more. By increasing the specific surface area, a smoother surface tends to be obtained. The specific surface area of the abrasive grains B is usually 100 m ² / g or less, preferably 90 m ² / g or less, more preferably 80 m ² / g or less. Higher polishing rates can be realized by the reduction of the specific surface area.

In case the polishing composition are embodiments containing abrasive grains B, the ratio of the weight of silica abrasive grains A contained in the polishing composition and (W _A) and the weight (W _B) of the abrasive B (W _A / W _B ) is not particularly limited. The weight ratio (W _A / W _B ) is preferably 0.25 or more, more preferably 0.35 or more, and still more preferably 0.4 or more from the viewpoint of facilitating the effects of the present invention. For example, 0.45 or more). From the viewpoint of balancing various performances (for example, polishing rate, surface accuracy of the surface to be polished after polishing, etc.), it is appropriate that the weight ratio (W _A / W _B ) is 0.9 or less, Preferably it is 0.8 or less, More preferably, it is 0.7 or less (for example, 0.6 or less).

  In the technology disclosed herein, it is preferable that the abrasive grains B do not contain α-alumina particles. In other words, the polishing composition disclosed herein can be preferably practiced in a manner substantially free of α-alumina abrasive grains. By this, it is possible to eliminate the quality deterioration (e.g., generation of scratches and depressions, residual alumina, and the like) due to the use of? -Alumina abrasive grains. Here, when substantially no α-alumina abrasive grains are contained, the proportion of α-alumina abrasive grains is 1% by weight or less (more preferably 0.5% by weight) based on the total solid content contained in the polishing composition. Hereinafter, typically, it is 0.1% by weight or less). Particularly preferred are polishing compositions in which the proportion of α-alumina abrasives is 0% by weight, ie, polishing compositions not containing α-alumina abrasives.

  In the technology disclosed herein, the abrasive grains B are preferably colloidal particles, and more preferably colloidal silica. According to the polishing composition containing the abrasive grains B, the effect of improving the surface accuracy of the surface to be polished (for example, the effect of suppressing long wavelength waviness, the effect of reducing surface roughness, etc.) is realized while realizing a high polishing rate. There is a tendency to be exhibited suitably.

  When the polishing composition disclosed herein contains a plurality of types of abrasive grains, the number of types of abrasive grains contained in the composition is generally grasped based on the difference in the external shape of the plurality of types of abrasive grains. can do. The difference in the external shape of the abrasive grains is, for example, at least one of the difference in average aspect ratio, the difference in average minor axis, the difference in average particle diameter, the difference in surface shape of particles (for example, the presence or absence of protrusions and the degree thereof) It can be one. The outer shape of the abrasive can be grasped by, for example, SEM (scanning electron microscope) observation. Moreover, each content and content ratio of several types of abrasive grains contained in polishing composition can be calculated | required based on the image analysis by SEM observation, for example. The polishing composition containing the plurality of types of abrasive grains is prepared, for example, by mixing the abrasive grains, water, an acid, and an optional component (such as an oxidizing agent) optionally used, in a desired amount ratio. It can be done.

<Water>
The polishing composition disclosed herein contains water in addition to the abrasive grains. As water, ion exchange water (deionized water), distilled water, pure water or the like can be used.
The polishing composition (typically a slurry composition) disclosed herein is preferably carried out, for example, in the form of having a non-volatile content (NV) of 5 g / L to 300 g / L. It can be done. More preferably, the above-mentioned NV is 10 g / L to 200 g / L.

<Acid>
The polishing composition disclosed herein contains an acid as a polishing accelerator in addition to the abrasive grains and water. Examples of the acid include inorganic acids (nitric acid, sulfuric acid, hydrochloric acid, phosphoric acid, sulfamic acid etc.) and organic acids (organic carboxylic acids having about 1 to 10 carbon atoms, organic phosphonic acids, organic sulfonic acids etc.) But not limited thereto. Specific examples of the organic acid include citric acid, maleic acid, malic acid, glycolic acid, succinic acid, itaconic acid, malonic acid, iminodiacetic acid, gluconic acid, lactic acid, mandelic acid, tartaric acid, crotonic acid, nicotinic acid, acetic acid And adipic acid, formic acid, oxalic acid, methyl acid phosphate, ethyl acid phosphate, ethyl glycol acid phosphate, isopropyl acid phosphate, phytic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, methanesulfonic acid and the like. Such an acid can function effectively as a polishing accelerator by being typically used in combination with the below-mentioned oxidizing agent. As a preferable acid from the viewpoint of polishing efficiency, methanesulfonic acid, sulfuric acid, nitric acid, phosphoric acid, sulfamic acid, phytic acid, 1-hydroxyethylidene-1,1-diphosphonic acid and the like are exemplified. Among these, nitric acid, sulfuric acid, phosphoric acid, sulfamic acid and methanesulfonic acid are preferable.

  The content of the acid in the polishing composition is preferably 1 g / L or more, more preferably 5 g / L or more. If the content of the acid is too low, the polishing rate may be reduced, which may be undesirable in practice. In addition, the content of the acid in the polishing composition is preferably 100 g / L or less, more preferably 50 g / L or less. If the content of the acid is too large, the surface accuracy of the object to be polished may be deteriorated, which may be undesirable in practice.

<Oxidizing agent>
The polishing composition disclosed herein may further contain an oxidizing agent, if necessary. Examples of the oxidizing agent include, but are not limited to, peroxides, nitric acid or salts thereof, peroxy acids or salts thereof, permanganic acid or salts thereof, chromic acid or salts thereof, and the like. As such an oxidizing agent, one type may be used alone, or two or more types may be used in combination as appropriate. Specific examples of the oxidizing agent include hydrogen peroxide, nitric acid, iron nitrate, aluminum nitrate, peroxodisulfuric acid, periodic acid, perchloric acid, hypochlorous acid and the like. Examples of preferred oxidizing agents include hydrogen peroxide, iron nitrate, peroxodisulfuric acid and nitric acid. The polishing composition disclosed herein can be particularly preferably practiced in a mode including at least hydrogen peroxide water as an oxidizing agent.

When the polishing composition contains an oxidizing agent, the content is preferably 1 g / L or more, more preferably 3 g / L or more, and still more preferably 4 g / L or more, based on the amount of the active ingredient. If the content of the oxidizing agent is too small, the rate at which the object to be polished is oxidized becomes slow, and the polishing rate decreases, which may be undesirable in practice.
When the polishing composition contains an oxidizing agent, the content is preferably 30 g / L or less, more preferably 15 g / L or less, based on the amount of the active ingredient. If the content of the oxidizing agent is too large, the surface accuracy of the object to be polished may be deteriorated, which may be undesirable in practice.

<Basic compound>
The polishing composition can contain a basic compound. Here, the basic compound refers to a compound having a function of increasing the pH of the composition by being added to the polishing composition. For example, hydroxides of alkali metals, carbonates and hydrogencarbonates, quaternary ammonium or salts thereof, ammonia, amines, phosphates and hydrogen phosphates, organic acid salts and the like can be mentioned. The basic compounds can be used alone or in combination of two or more.

Potassium hydroxide, sodium hydroxide etc. are mentioned as a specific example of the hydroxide of an alkali metal.
Specific examples of the carbonate or hydrogen carbonate include ammonium hydrogen carbonate, ammonium carbonate, potassium hydrogen carbonate, potassium carbonate, sodium hydrogen carbonate, sodium carbonate and the like.
Specific examples of the quaternary ammonium or salts thereof include quaternary ammonium hydroxides such as tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide and tetrabutyl ammonium hydroxide.
Specific examples of the amine include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N- (β-aminoethyl) ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine And piperazine hexahydrate, 1- (2-aminoethyl) piperazine, N-methyl piperazine, guanidine, azoles such as imidazole and triazole, and the like.
Specific examples of phosphate and hydrogen phosphate include alkalis such as tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, trisodium phosphate, disodium hydrogen phosphate and sodium dihydrogen phosphate Metal salts are mentioned.

<Surfactant>
The polishing composition may contain a surfactant for the purpose of improving the cleaning efficiency after polishing by imparting hydrophilicity to the surface to be polished after polishing and preventing adhesion of dirt and the like. The surfactant may be any of an anionic surfactant, a cationic surfactant, an amphoteric surfactant or a nonionic surfactant.

Specific examples of the anionic surfactant include polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl sulfate, alkyl sulfate, polyoxyethylene alkyl sulfate, alkyl sulfate, alkyl benzene sulfonic acid, alkyl phosphate, polyoxy acid Ethylene alkyl phosphate, polyoxyethylene sulfosuccinic acid, alkyl sulfosuccinic acid, alkyl naphthalene sulfonic acid, alkyl diphenyl ether disulfonic acid, polyacrylic acid, sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecyl benzene sulfonate, sodium polyoxyethylene alkyl ether sulfate , Polyoxyethylene alkyl phenyl ether ammonium sulfate, polyoxyethylene alkyl phenyl ether sulfur Sodium, and salts thereof.
Other specific examples of the anionic surfactant include polyalkyl aryl sulfonic acid systems such as naphthalene sulfonic acid formaldehyde condensate, methyl naphthalene sulfonic acid formaldehyde condensate, anthracene sulfonic acid formaldehyde condensate, benzene sulfonic acid formaldehyde condensate and the like Compound; melamine formalin resin sulfonic acid type compound such as melamine sulfonic acid formaldehyde condensate; lignin sulfonic acid type compound such as lignin sulfonic acid, modified lignin sulfonic acid; aromatic amino sulfone such as aminoaryl sulfonic acid-phenol-formaldehyde condensate Acid compounds; others, polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyisoamylene sulfonic acid, polystyrene sulfonic acid; Etc. The.

Specific examples of the cationic surfactant include alkyl trimethyl ammonium salts, alkyl dimethyl ammonium salts, alkyl benzyl dimethyl ammonium salts, alkyl amine salts and the like.
Specific examples of amphoteric surfactants include alkyl betaines, alkylamine oxides and the like.
Specific examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, sorbitan fatty acid ester, glycerin fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene alkylamine, alkyl alkanolamide and the like. Be

  One of these surfactants may be used alone, or two or more thereof may be used in combination. Moreover, as salts of such surfactants, alkali metal salts such as sodium salts and potassium salts are preferable.

  In the polishing composition of the aspect containing a surfactant, it is suitable that the content of the surfactant is, for example, 0.005 g / L or more. The content is preferably 0.01 g / L or more, more preferably 0.1 g / L or more, from the viewpoint of surface smoothness and the like after polishing. Further, from the viewpoint of polishing rate etc., the content is suitably 100 g / L or less, preferably 50 g / L or less, for example 10 g / L or less.

<Other ingredients>
The polishing composition disclosed herein is a polishing composition of this type such as a dispersing agent, a chelating agent, a pH adjusting agent, an antiseptic agent, an antifungal agent, etc., to the extent that the effects of the present invention are not significantly impaired. Typically, known additives which can be used for a magnetic disk substrate (for example, a polishing composition used for primary polishing of a Ni-P substrate) may further be contained, as needed.

  Examples of the dispersant include polycarboxylic acid-based dispersants such as polycarboxylic acid sodium salt and polycarboxylic acid ammonium salt, naphthalenesulfonic acid-based dispersants such as naphthalenesulfonic acid sodium salt and naphthalenesulfonic acid ammonium salt, and alkylsulfonic acid There may be mentioned, for example, system dispersants, polyphosphate dispersants, polyalkylene polyamine dispersants, quaternary ammonium dispersants, alkylpolyamine dispersants, alkylene oxide dispersants, polyhydric alcohol ester dispersants and the like.

  Examples of chelating agents include aminocarboxylic acid-based chelating agents and organic phosphonic acid-based chelating agents. Examples of aminocarboxylic acid chelating agents include ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetate, nitrilotriacetic acid, sodium nitrilotriacetate, ammonium nitrilotriacetate, ammonium hydroxyethylethylenediaminetriacetic acid, sodium hydroxyethylethylenediaminetriacetate, diethylenetriaminepentaacetic acid Sodium diethylene triamine pentaacetate, triethylene tetramine hexaacetic acid and sodium triethylene tetramine hexaacetate. Examples of organic phosphonic acid type chelating agents include 2-aminoethyl phosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylene phosphonic acid), ethylene diamine tetrakis (methylene phosphonic acid), diethylene triamine penta (methylene phosphonic acid) 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-2,3,4-tricarboxylic acid and α-methylphosphorus Includes nosuccinic acid. Among these, organic phosphonic acid type chelating agents are more preferable, and ethylenediamine tetrakis (methylene phosphonic acid) and diethylene triamine penta (methylene phosphonic acid) are mentioned as preferable one among them. Particularly preferred chelating agents include ethylenediamine tetrakis (methylene phosphonic acid).

  Examples of preservatives and fungicides include isothiazoline preservatives such as 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one, p-hydroxybenzoic acid esters And phenoxyethanol.

  The polishing composition disclosed herein may further contain a water-soluble polymer. By further containing the water-soluble polymer, the surface roughness of the object to be polished (for example, the magnetic disk substrate) after being polished by the polishing composition can be further reduced. Examples of water-soluble polymers include polyalkylaryl sulfonic acid compounds such as naphthalene sulfonic acid formaldehyde condensate, methyl naphthalene sulfonic acid formaldehyde condensate and anthracene sulfonic acid formaldehyde; melamine formalin resin sulfonic acid such as melamine sulfonic acid formaldehyde condensate and the like Compounds; Lignin sulfonic acid compounds such as lignin sulfonic acid and denatured lignin sulfonic acid; Aromatic amino sulfonic acid compounds such as aminoaryl sulfonic acid-phenol-formaldehyde condensate; and others, polyisoprene sulfonic acid, polyvinyl sulfonic acid, poly Allyl sulfonic acid, polyisoamylene sulfonic acid, polystyrene sulfonate, polyacrylate, polyvinyl acetate, polymaleic acid, polyitaconic acid, polyvinyl alcohol , Polyglycerin, polyvinyl pyrrolidone, copolymer of isoprene sulfonic acid and acrylic acid, polyvinyl pyrrolidone poly acrylic acid copolymer, polyvinyl pyrrolidone vinyl acetate copolymer, diallylamine hydrochloride sulfur dioxide copolymer, carboxymethyl cellulose, carboxy Methylcellulose salts, hydroxyethylcellulose, hydroxypropylcellulose, pullulan, chitosan, chitosan salts and the like can be mentioned.

<Use>
The polishing composition disclosed herein can be preferably applied, for example, to the polishing of a disk substrate (Ni-P substrate) having a nickel phosphorus plating layer on the surface of the substrate disk. In particular, it is suitable as a polishing composition for primary polishing of such a disk substrate. The base disk may be made of, for example, aluminum alloy, glass, glassy carbon, or the like. It may be a disk substrate provided with a metal layer or a metal compound layer other than the nickel phosphorus plating layer on the surface of such a base disk. Among them, it is suitable as a polishing composition for primary polishing of a Ni-P substrate having a nickel phosphorus plating layer on a base disk made of aluminum alloy. In such applications, it is particularly meaningful to apply the techniques disclosed herein.

  In addition, the polishing composition disclosed herein is, for example, Schmitt Measurement System Inc. Polish (typically primary polish) a magnetic disk substrate with a surface roughness (arithmetic mean roughness (Ra)) of approximately 20 Å to 300 Å as measured by the company's laser scan type surface roughness meter “TMS-3000 WRC” It is suitable for the application adjusted to a surface roughness (arithmetic mean roughness (Ra)) of 10 Å or less. In such applications, it is particularly meaningful to apply the techniques disclosed herein.

<Abrasive fluid>
The polishing composition disclosed herein is typically supplied to a polishing target (for example, a magnetic disk substrate) in the form of a polishing liquid containing the polishing composition, and used for polishing the polishing target. . The polishing solution may be prepared, for example, by diluting a polishing composition. Alternatively, the polishing composition may be used as it is as a polishing liquid. That is, the concept of the polishing composition in the art disclosed herein includes both a polishing liquid and a concentrate diluted and used as a polishing liquid.

  The content of the abrasive grains in the polishing liquid (the total content of the abrasive grains in the case of containing plural kinds of abrasive grains) is typically 5 g / L or more, and preferably 10 g / L or more, 30 g It is more preferable that it is / L or more. Higher polishing rates can be achieved by increasing the abrasive content. Further, from the viewpoint of the surface smoothness of the substrate after polishing and the stability of polishing, the content is usually 250 g / L or less, preferably 200 g / L or less, more preferably 150 g / L or less. More preferably, it is 100 g / L or less.

  The content of the acid in the polishing liquid (the total content thereof in the embodiment including a plurality of acids) can be, for example, 0.1 g / L or more. The content is preferably 0.5 g / L or more, more preferably 1 g / L or more, and still more preferably 5 g / L or more from the viewpoint of polishing rate and the like. Further, from the viewpoint of storage stability and the like of the polishing composition, the content is suitably 70 g / L or less, preferably 50 g / L or less, for example 30 g / L or less.

In the embodiment including the oxidizing agent, the content of the oxidizing agent in the polishing liquid (the total content thereof when containing a plurality of oxidizing agents) is, for example, 0.1 g / L or more based on the amount of the active ingredient. can do. The content is preferably 0.5 g / L or more, more preferably 1 g / L or more, from the viewpoint of polishing rate and the like. In addition, from the viewpoint of the economy of the polishing composition, the content of the oxidizing agent is suitably 100 g / L or less, preferably 75 g / L or less, more preferably 60 g / L or less, based on the amount of the active ingredient. is there. The preferred content range may also vary depending on the type of oxidizing agent used. For example, when using hydrogen peroxide as the oxidizing agent, the content thereof is usually about 0.1 to 50 g / L as the H ₂ O ₂ concentration, and preferably 1 to 30 g / L. Moreover, when using iron nitrate (III) nonahydrate as an oxidizing agent, the content thereof is usually about 20 to 100 g / L, and preferably 30 to 75 g / L.

  The pH of the polishing solution is preferably 4 or less, more preferably 3 or less, from the viewpoint of polishing rate, surface smoothness and the like. A pH adjuster such as an organic acid or an inorganic acid can be contained as necessary so that the above pH is realized in the polishing liquid. The above pH can be preferably applied to, for example, a polishing solution (particularly, a polishing solution for primary polishing) used for polishing a magnetic disk substrate having a nickel phosphorus plating layer.

  In the embodiment including the water-soluble polymer, the content of the water-soluble polymer in the polishing liquid (the total content thereof in the embodiment including a plurality of water-soluble polymers) is, for example, 0.01 g / L or more. Is appropriate. The content is preferably 0.05 g / L or more, more preferably 0.08 g / L or more, and still more preferably 0. 5 g / L from the viewpoint of the surface smoothness of the object to be polished (for example, magnetic disk substrate) after polishing. It is 1 g / L or more. Further, from the viewpoint of polishing rate etc., the content is suitably 10 g / L or less, preferably 5 g / L or less, for example 1 g / L or less.

<Polishing>
The polishing composition disclosed herein can be suitably used for polishing an object to be polished (for example, a substrate that is a raw material of a magnetic disk substrate) in a mode including, for example, the following operations. Hereinafter, a preferred embodiment of a method for polishing an object to be polished using the polishing composition disclosed herein will be described.
That is, a polishing liquid (typically, a slurry-like polishing liquid, which may be referred to as a polishing slurry) including any of the polishing compositions disclosed herein is prepared. The preparation of the polishing solution may include preparing the polishing solution by performing operations such as concentration adjustment (for example, dilution) and pH adjustment on the polishing composition. Alternatively, the polishing composition may be used as it is as a polishing liquid.

  Then, the polishing liquid is supplied to the object to be polished and polished by a conventional method. For example, an object to be polished which is a raw material of a substrate is set in a general polishing apparatus, and a polishing liquid is supplied to the surface (surface to be polished) of the object to be polished through the polishing pad of the polishing apparatus. Typically, while the polishing liquid is continuously supplied, the polishing pad is pressed against the surface of the object to be moved relative to each other (e.g., rotational movement). Polishing of the object to be polished is completed through this polishing process.

  The polishing process as described above may be part of the process of manufacturing a substrate (e.g., a Ni-P substrate). Thus, according to this specification, there is provided a method of manufacturing a substrate comprising the above-mentioned polishing step.

  The polishing composition disclosed herein can be preferably used for primary polishing of an object to be polished. Therefore, according to this specification, there is provided a method of manufacturing a substrate including a primary polishing step using the above-mentioned polishing composition. The substrate manufacturing method may include a final polishing step (finish polishing step) after the primary polishing step. This final polishing step can be carried out in the same manner as the conventionally known method. As the polishing composition used in the final polishing step, a polishing composition containing colloidal silica abrasive can be preferably employed. The finish polishing step may be, for example, a step of polishing an object to be polished using a polishing composition containing substantially only colloidal silica abrasive grains as abrasive grains.

<Concentrate>
The polishing composition disclosed herein may be in a concentrated form (i.e., in the form of a concentrate of the polishing liquid) before being supplied to the object to be polished. The polishing composition in such a concentrated form is advantageous from the viewpoints of convenience and cost reduction in production, distribution, storage, and the like. The concentration factor can be, for example, about 1.5 times to 50 times. From the viewpoint of storage stability and the like of the concentrate, usually, a concentration factor of about 2 to 20 (typically 2 to 10) is appropriate.

  Thus, the polishing composition in the form of a concentrate can be suitably used in a mode in which the polishing liquid is prepared by diluting at a desired timing, and the polishing liquid is supplied to the object to be polished. The dilution can be typically performed by adding water to the concentrate and mixing.

  The content of the abrasive grains in the concentrate (the total content of the abrasive grains in the case of containing a plurality of abrasive grains) can be, for example, less than 750 g / L. From the viewpoint of storage stability of the polishing composition, the content is suitably less than 650 g / L, preferably less than 600 g / L. In addition, the content of the abrasive can be, for example, 10 g / L or more, preferably 20 g / L or more, and more preferably, from the viewpoint of convenience and cost reduction in production, distribution, storage, etc. It is 30 g / L or more (for example, 50 g / L or more).

  The polishing composition disclosed herein may be a one-part type or a multi-part type including a two-part type. For example, solution A containing a part of components of the polishing composition (typically, components other than water) and solution B containing the remaining components are mixed to polish the object to be polished. It may be configured to be used for

  According to the polishing composition disclosed herein or polishing using the composition, the surface of the object to be polished can be efficiently planarized without using alumina abrasive grains as an essential component. For this reason, for example, the ratio of the alumina abrasive grains in the abrasive grains contained in the polishing composition is made smaller than that of the conventional general polishing composition containing the alumina abrasive grains, or the alumina abrasive grains Even if the composition is not substantially contained, polishing efficiency that can be preferably applied to primary polishing of a magnetic disk substrate such as a Ni-P substrate can be realized. According to primary polishing using such a polishing composition, it is possible to suppress or prevent the occurrence of defects caused by alumina abrasive grains or the remaining of alumina. This improves the surface condition after primary polishing, and a more accurate surface can be realized after final polishing.

  Further, according to the polishing composition disclosed herein or polishing using the composition, the surface of the object to be polished can be efficiently planarized using the silica abrasive grain A. For example, in a conventional general polishing composition containing only colloidal silica abrasive as an abrasive, the polishing rate can be improved by replacing a part or all of the colloidal silica abrasive with silica abrasive A. it can.

  The following examples illustrate some of the embodiments of the present invention, but are not intended to limit the present invention to those shown.

<Preparation of Silica Abrasive Grain A>
The raw materials of the silica abrasive grain A used in each of the following examples are as follows.
Silica S1: Precipitated silica (specific surface area 18.7 m ² / g, average particle diameter 16200 nm)
Silica S2: gel method silica (specific surface area 49.41 m ² / g, average particle diameter 3800 nm)
Silica S3: gel method silica (specific surface area 296 m ² / g, average particle diameter 6400 nm)

(Examples 1 to 8)
Silica S1 was used as a raw material of the silica abrasive grain A. As shown in the column of "Sintering temperature" in Table 1, silica S1 was sintered by holding for about 2 hours in a heating furnace maintained at a temperature of 600 to 1000 ° C. The calcined silica obtained in this manner was used as silica abrasive grains A according to Examples 6 to 8. Furthermore, in Examples 1 to 5, the above-mentioned calcined silica S1 was put into a ball mill and crushed to a desired particle diameter. The crushed silica thus obtained was used as silica abrasive grains A according to Examples 1 to 5.

(Examples 9 to 11)
As a raw material of the silica abrasive grain A, silica S2 was used. Silica S2 was fired by holding for about 2 hours in a heating furnace maintained at a temperature of 600 to 1000 ° C., as shown in the column of “Firing temperature” in Table 1. The calcined silica obtained in this manner was used as silica abrasive grains A according to Examples 9 to 11.

(Example 12)
As a raw material of the silica abrasive grain A, silica S3 was used. Silica S3 was fired by holding for about 2 hours in a heating furnace maintained at a temperature of 1000 ° C. as shown in the column of “Firing temperature” in Table 1. The calcined silica thus obtained is referred to as silica abrasive grain A according to Example 10.

(Comparative example 1)
As the silica abrasive grains A according to Comparative Example 1, silica S1 was used as it was.

(Comparative example 2)
As the silica abrasive grains A according to Comparative Example 2, silica S3 was used as it was.

Incidentally, the abrasive grains of the specific surface area (hereinafter, also referred to as _{S A.)} Were measured using a Micromeritics Tex manufactured by surface area measuring apparatus "Flow Sorb II 2300". In addition, the average particle diameter of the abrasive grains (50% volume average particle diameter, hereinafter also referred to as D _P ) is measured using a laser diffraction / scattering particle size distribution measuring apparatus ("LA-950" manufactured by Horiba, Ltd.) The refractive index of silica was measured as 1.45.

The specific surface area (S _A ) and the average particle size (D _P ) of the silica abrasive grains A according to the example and the comparative example are collectively shown in Table 1.

<Preparation of Abrasive Grain B>
In Examples 1 to 12 and Comparative Examples 1 and 2, colloidal silica having a specific surface area of 80 m ² / g and an average particle size (50% volume average particle size) of 110 nm was used as the abrasive grains B. In the reference example, colloidal silica having a specific surface area of 70 m ² / g and an average particle size (50% volume average particle size) of 95 nm was used as the abrasive grains B.

<Preparation of Polishing Composition>
(Examples 1 to 12, Comparative Examples 1 and 2)
The above silica abrasive A, the above abrasive B, nitric acid, 31% hydrogen peroxide water and deionized water are mixed, and 30 g / L of silica abrasive A and 30 g / L of abrasive B are mixed. A polishing composition containing 8 g / L of nitric acid and 40 g / L of 31% hydrogen peroxide solution was prepared. These polishing compositions were used as the polishing compositions according to Examples 1 to 12 and Comparative Examples 1 and 2.

(Reference example)
As a reference example, a polishing composition containing no silica abrasive grain A was prepared. Specifically, abrasive grains B according to the above reference example, nitric acid, 31% hydrogen peroxide water, and deionized water are mixed, and abrasive grains B are 60 g / L, nitric acid 20 g / L, 31 A polishing composition containing 20 g / L of hydrogen peroxide solution was prepared. The polishing composition produced in this manner was used as a polishing composition according to the reference example.

<Abrasive disc>
Using the polishing composition according to each example, the substrate to be polished was polished under the following conditions. As a substrate to be polished, an aluminum substrate for a hard disk provided with an electroless nickel phosphorous plating layer on the surface was used. The above-mentioned substrate to be polished (hereinafter also referred to as "Ni-P substrate") has a diameter of 3.5 inches (a donut shape having an outer diameter of about 95 mm and an inner diameter of about 25 mm) and a thickness of 1.75 mm. (The arithmetic average roughness of the nickel phosphorus plating layer measured by a laser scan type surface roughness meter “TMS-3000 WRC” manufactured by Schmitt Measurement System Inc.) was 130 Å.

[Polishing conditions]
Polishing device: Double-side polishing machine manufactured by System Seiko Co., Ltd., model "9.5 B-5 P"
Polishing pad: Polyurethane pad made by Filwell, trade name "CR200"
Number of inserted Ni-P substrates: 15 sheets (5 sheets / carrier x 3 carriers)
Polishing fluid supply rate: 135 mL / min Polishing load: 120 g / cm ²
Upper surface plate rotation speed: 27 rpm
Lower surface plate rotation speed: 36 rpm
Sun gear (sun gear) speed: 8 rpm
Polishing amount: Thickness of about 2.2μm in total on both sides of each substrate

<Polishing rate>
In the column of "Polishing rate" in Table 2, the polishing rate when the above-mentioned Ni-P substrate is polished using each polishing composition is calculated, and these are set to 100% of the polishing rate of the reference example. The converted value is shown. The polishing rate was determined based on the following formula.
Polishing rate [μm / min] = weight loss of substrate due to polishing [g] / (area of substrate [cm ² ] × density of nickel phosphorus plating [g / cm ³ ] × polishing time [min]) × 10 ⁴

Surface accuracy
In the column of “suppression of long wavelength waviness” in Table 2, using “Optiflat III” manufactured by KLA Tencor (US), cut in a range of 20 mm to 44 mm in radius from the center of the polished Ni-P substrate The value [Å] of the arithmetic mean waviness (Wa) measured under the condition of the off value 5 mm was measured, and the results evaluated in the following three stages were described.
◎: Wa less than 4 Å ○: Wa greater than 4 Å and less than 5 Å x: Wa greater than 5 Å

In the column of “reduction of surface roughness” in Table 2, Schimitt Measurement System Inc. The surface roughness (arithmetic mean roughness (Ra)) [Å] of the polished Ni-P substrate is measured using a laser scanning surface roughness meter “TMS-3000 WRC” manufactured by Co., Ltd., and the following three steps The results of the evaluation are listed.
:: Ra is less than 5 Å ○: Ra is 5 Å or more and less than 10 Å ×: Ra is 10 Å or more

  As is clear from the results shown in Table 2, the polishing compositions according to Examples 1 to 12 using the calcined material as the silica abrasive grain A were comparative examples 1 using the uncalcined silica abrasive grain A. The polishing rate was about 1.7 to 10 times higher than that of 2. In addition, the polishing compositions according to Examples 1 to 12 containing the fired silica abrasive grains A were about 1.1 to 1.9 times as large as the reference examples using only colloidal silica as the abrasive grains. It was found that it showed a high polishing rate.

  The polishing composition containing silica abrasives A prepared by firing at a firing temperature of 1200 ° C. showed a polishing rate as high as that in Examples 1 to 12, but the surface accuracy of the surface to be polished was Resulted in a slightly inferior result.

  In addition, the polishing compositions according to Examples 1 to 5 using the crushed abrasive as the silica abrasive grain A are more compared to the polishing compositions according to Examples 6 to 8 which are not crushed. It was found that the polishing rate was high and the surface accuracy on the surface to be polished was further improved.

  As mentioned above, although the specific example of this invention was described in detail, these are only an illustration and do not limit a claim. The art set forth in the claims includes various variations and modifications of the specific examples illustrated above.

Claims (8)

A polishing composition used for polishing a nickel phosphorus plated disk substrate, comprising:
Abrasive grains, the acid and water only contains,
The abrasive comprises silica abrasive A,
The polishing composition, wherein the silica abrasive grain A is a raw material silica fired.   The polishing composition according to claim 1, wherein the silica abrasive grain A is fired at a firing temperature of 600 ° C. or more and 1100 ° C. or less.   The polishing composition according to claim 1, wherein the silica abrasive grain A is further crushed after being fired.   The polishing composition according to any one of claims 1 to 3, further comprising an oxidizing agent.   The polishing composition according to any one of claims 1 to 4, which is used in the previous step of the final polishing step. A method of producing a polishing composition for use in the polishing of nickel phosphorous plated disk substrates :
Preparing silica abrasives A by calcinating the raw material silica;
Mixing the abrasive containing the silica abrasive A, acid and water;
A method of producing a polishing composition, comprising: A method of manufacturing a nickel phosphorus plated disk substrate , comprising:
A substrate manufacturing method including the grinding process A which supplies the constituent for polish according to any one of claims 1 to 5 to a polish subject which is a raw material of said substrate, and polishes the polish subject. The substrate manufacturing method according to claim 7 , further comprising: a finishing polishing step of supplying a polishing composition containing colloidal silica abrasive grains to the polishing object after the polishing step A to polish the polishing object.