JP7061859B2 - Method for manufacturing polishing composition and magnetic disk substrate - Google Patents

Description

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

In the manufacture of magnetic disk substrates, polishing (primary polishing) that emphasizes polishing efficiency (for example, polishing rate) is generally performed before the final polishing process that is performed to finish the surface of the final product with high accuracy. .. For example, a highly accurate surface can be efficiently realized by performing at least primary polishing and final polishing on a disc substrate (Ni-P substrate) plated with nickel phosphorus. Patent Documents 1 and 2 are mentioned as technical documents relating to a polishing composition used for polishing a magnetic disk substrate or the like.

Japanese Unexamined Patent Publication No. 2010-135052 Japanese Unexamined Patent Publication No. 2017-25295

In recent years, it has been studied to use silica abrasive grains having a small average particle size for a polishing composition used for polishing a disk substrate such as a Ni-P substrate from the viewpoint of realizing a higher quality surface. However, the polishing composition containing fine particles of silica abrasive grains tends to be inferior in processing power, and is used in polishing that requires a high polishing rate, such as primary polishing of a disk substrate such as a Ni-P substrate. In some cases, such a request may not be fully met. In addition, the dispersion stability of the polishing composition may affect the surface quality after polishing. Therefore, in order to stably realize high quality (for example, a surface with less pit generation and reduced waviness) on the surface after polishing, a polishing composition having good dispersion stability is desirable.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polishing composition capable of achieving both a high polishing rate and excellent dispersion stability. Another related object is to provide a method for manufacturing a magnetic disk substrate using the above-mentioned polishing composition.

According to the present invention, a polishing composition is provided. This polishing composition contains abrasive grains, an acid, an oxidizing agent and water. The abrasive grains contain at least silica particles. The average secondary particle diameter of the abrasive grains measured by the dynamic scattering method is 50 nm or more and 300 nm or less. The pH of the polishing composition is 1-2. The amount of sodium hydroxide required to raise the pH by 1.0 is 0.06 mol / L or more and 1 mol / L or less. According to the polishing composition satisfying the above-mentioned characteristics, a high polishing rate and excellent dispersion stability can be achieved at a high level.

In a preferred embodiment of the polishing composition disclosed herein, colloidal silica is included as the silica particles. By using colloidal silica as the silica particles, the effect of the present invention can be more preferably exhibited.

The polishing composition disclosed herein is used for polishing a magnetic disk substrate. Among them, a nickel phosphorus substrate (Ni-P substrate) is mentioned as a preferable polishing object. When the polishing composition is applied to the magnetic disk substrate, the surface quality of the surface of the magnetic disk substrate after polishing can be improved and a high polishing rate can be achieved.

The polishing composition disclosed here is suitable as a polishing composition used in the pre-process of the finish polishing step. For example, the polishing composition is suitably used for primary polishing of a magnetic disk substrate. Since the polishing composition disclosed herein can exhibit a high polishing rate, it is particularly useful to be used in a polishing process that requires high polishing efficiency, such as the primary polishing.

Further, according to the present invention, a method for manufacturing a magnetic disk substrate is provided. The manufacturing method includes a step of polishing a magnetic disk substrate using any of the polishing compositions disclosed herein. According to such a manufacturing method, a magnetic disk substrate having a high-quality surface can be manufactured with high productivity.

Hereinafter, preferred embodiments of the present invention will be described. Matters other than those specifically mentioned in the present specification and necessary for carrying out the present invention can be grasped as design matters of those skilled in the art based on the prior art in the art. The present invention can be carried out based on the contents disclosed in the present specification and the common general technical knowledge in the art.

The polishing composition disclosed herein is a polishing composition used for polishing (preferably primary polishing) a magnetic disk substrate, and contains abrasive grains, an acid, an oxidizing agent, and water. This polishing composition has a pH of 1 to 2, and the amount α of sodium hydroxide (NaOH) required to raise the pH by 1.0 is 0.06 mol / L or more and 1 mol / L. It is as follows.

<Amount of sodium hydroxide α>
In the technique disclosed herein, the amount of sodium hydroxide α required to raise the pH of the polishing composition by 1.0 shall be measured as follows. That is, a 0.1 mol / L sodium hydroxide aqueous solution (manufactured by Kanto Chemical Co., Ltd.) was dropped by immersing the electrode of the pH meter in the polishing composition (liquid temperature 25 ° C.) to be measured and stirring, and the pH was the initial value. Titration of 0.1 mol / L sodium hydroxide aqueous solution from to 1.0 increase is measured. Then, the sodium hydroxide amount α can be obtained by using the following formula (1).
α (mol / L) = 0.1 × A ÷ B (1)
A: Titration of 0.1 mol / L sodium hydroxide aqueous solution required to raise pH by 1.0 (L)
B: Volume (L) of the polishing composition

The polishing composition disclosed herein has a sodium hydroxide amount α of 0.06 mol / L or more, which is required to raise the pH by 1.0. As a result, a higher polishing rate can be realized as compared with the conventional polishing composition in which the sodium hydroxide amount α is less than 0.06 mol / L. The reason why such an effect can be obtained is considered as follows, for example. That is, from the viewpoint of processability, the pH of the polishing composition is preferably low. However, even when a polishing composition having a low pH is used, when the polishing composition is applied to polishing a magnetic disk substrate, the metal on the substrate surface (for example, Ni in the case of a nickel phosphorus substrate) elutes as the polishing progresses. Then, the pH rises due to the consumption of hydrogen ions. As a result, the polishing speed tends to decrease. On the other hand, in polishing using the polishing composition having the sodium hydroxide amount α of 0.06 mol / L or more, the polishing composition has an appropriate buffering capacity, so that even if the polishing proceeds, the polishing has an appropriate buffering capacity. The decrease in hydrogen ions is suppressed, and pH fluctuations are unlikely to occur (typically, pH 1-2 is maintained). This is considered to contribute to the improvement of the polishing rate. However, it is not limited to this.

The amount of sodium hydroxide α required to raise the pH of the polishing composition by 1.0 is preferably 0.08 mol / L or more, more preferably 0.1 mol / L or more, still more preferably 0. It is 12 mol / L or more, particularly preferably 0.15 mol / L or more. A polishing composition having a sodium hydroxide amount α of a predetermined value or more is less likely to cause pH fluctuation during polishing. Therefore, the effect of applying the techniques disclosed herein is appropriately exerted. On the other hand, if the sodium hydroxide amount α is too large, the dispersion stability of the polishing composition may be lowered, and the surface quality may tend to be lowered. From the viewpoint of achieving better surface accuracy (for example, a surface with reduced waviness) while maintaining a high polishing rate, it is appropriate that the sodium hydroxide amount α is approximately 1 mol / L or less. Yes, preferably 0.8 mol / L or less, more preferably 0.6 mol / L or less, still more preferably 0.5 mol / L or less. The technique disclosed herein is, for example, in an embodiment in which the sodium hydroxide amount α is 0.06 mol / L or more and 1 mol / L or less (preferably 0.08 mol / L or more and 0.4 mol / L or less). It can be preferably carried out.

The amount α of sodium hydroxide required to raise the pH of the polishing composition by 1.0 is, for example, the type and concentration of the acid contained in the polishing composition (when a plurality of types of acids are contained, those types and the like). It can be adjusted by changing the compounding ratio). That is, by appropriately selecting the type, concentration and compounding ratio of the acid, the amount of sodium hydroxide α required to raise the pH of the polishing composition by 1.0 is adjusted to an appropriate range disclosed herein. can do. In addition, as a method of adjusting the amount α of the sodium hydroxide to an appropriate range, an acid in the system is added by adding a basic compound having an appropriate concentration to a single or multiple kinds of acids at a certain concentration. A method such as adjusting the concentration to adjust the amount α of the sodium hydroxide to an appropriate range can be adopted. The method for controlling the amount α of sodium hydroxide can be used alone or in combination.

<pH>
The pH (initial value) of the polishing composition is approximately 2.0 or less. From the viewpoint of polishing efficiency and the like, the pH of the polishing composition is preferably 1.9 or less, more preferably 1.8 or less. In some embodiments, the pH may be, for example, 1.7 or less, or 1.6 or less (eg, less than 1.5). The pH of the polishing composition is usually 1.0 or higher. From the viewpoint of suppressing damage to the polishing apparatus, the pH of the polishing composition is preferably 1.05 or higher, more preferably 1.1 or higher, still more preferably 1.2 or higher. The technique disclosed herein can be preferably carried out, for example, in an embodiment in which the pH of the polishing composition is 1.0 or more and 2.0 or less (preferably 1.1 or more and 1.6 or less). The above pH can be preferably applied to a polishing composition for polishing a magnetic disk substrate such as a nickel phosphorus substrate. In particular, it can be preferably applied to a polishing composition for primary polishing.
In the technique disclosed herein, the pH of the polishing composition can be grasped by calibrating the pH of the polishing composition at three points using a pH meter and then placing the glass electrode in the composition to be measured for measurement. .. The standard buffer is, for example, oxalate pH standard solution: pH 1.68 (25 ° C.), phthalate pH buffer solution: pH 4.01 (25 ° C.), neutral phosphate pH buffer solution: pH 6.86 ( 25 ° C.).

<Polishing composition>
(Abrasion grain)
The polishing composition disclosed herein contains abrasive grains containing at least silica particles. The abrasive grains have a specific average secondary particle size. That is, the average secondary particle diameter of the abrasive grains measured by the dynamic scattering method is 50 nm or more. The average secondary particle diameter of the abrasive grains is preferably 60 nm or more, more preferably 80 nm or more, still more preferably 90 nm or more, and particularly preferably 100 nm or more from the viewpoint of polishing rate and the like. The average secondary particle diameter of the abrasive grains may be, for example, 120 nm or more, and typically 140 nm or more. Further, the average secondary particle diameter of the abrasive grains may be approximately 300 nm or less. From the viewpoint of obtaining a higher quality surface, the average secondary particle diameter is preferably 280 nm or less, more preferably 250 nm or less, still more preferably 220 nm or less, and particularly preferably 200 nm or less. The technique disclosed herein can be preferably carried out, for example, by using abrasive particles having an average secondary particle diameter of 50 nm or more and 300 nm or less (more preferably 100 nm or more and 200 nm or less, for example, 120 nm or more and 180 nm or less).

The average secondary particle size of the abrasive grains can be grasped by measuring the particle size based on the dynamic light scattering method using the abrasive grain-containing liquid containing the abrasive grains as the measurement sample. As a specific procedure, water is added to the abrasive grain-containing liquid containing the abrasive grains to be measured (which may be one type of abrasive grain particles or a mixture of two or more types of abrasive grain particles). An aqueous sodium oxide solution is added to prepare an abrasive grain-containing liquid having a pH of 10 (abrasive particle concentration: 10% by weight). Then, the particles are dispersed for 90 seconds with a 50 kHz ultrasonic disperser, the particles dispersed in the abrasive grain-containing liquid are irradiated with laser light, and the particles are diluted with a sodium hydroxide aqueous solution (pH 10 adjustment) to be suitable for measurement. After adjusting to the scattering intensity, the particle size is measured by detecting the scattered light. The refractive index used for the measurement is 1.45. This particle size measurement can be performed using, for example, the model "UPA-UT151" manufactured by Nikkiso Co., Ltd. Further, as the ultrasonic disperser, for example, a model "Tetora150" manufactured by Nikkaki Bios Co., Ltd. can be used. The same applies to the examples described later.

The average primary particle diameter of the abrasive grains is not particularly limited, but is preferably 10 nm or more, more preferably 20 nm or more, still more preferably 30 nm or more, and particularly preferably 35 nm or more. Higher polishing rates can be achieved by increasing the average primary particle size. Further, from the viewpoint of obtaining a surface with higher surface accuracy, the average primary particle diameter is preferably 150 nm or less, more preferably 100 nm or less, still more preferably 80 nm or less, and particularly preferably 60 nm or less.

In the technique disclosed herein, the average primary particle size of the abrasive grains means the average particle size obtained based on the BET method. For example, when the abrasive grains are silica abrasive grains (that is, abrasive grains made of silica particles), the average primary particle diameter of the silica abrasive grains is D1 (nm) from the specific surface area S (m ² / g) measured by the BET method. ) = (6000 / 2.2) / S can be calculated. 2.2 in this formula is the value of the specific gravity of silica, which is the particle size of silica. The specific surface area can be measured, for example, by using a surface area measuring device manufactured by Micromeritex, trade name "Flow Sorb II 2300".

Although not particularly limited, the number average aspect ratio of the abrasive grains may be, for example, 1.0 or more. From the viewpoint of polishing rate and the like, in some embodiments, the average aspect ratio may be, for example, 1.02 or more, 1.05 or more, 1.10 or more, or 1.15 or more. Further, from the viewpoint of making it easy to efficiently improve the surface accuracy, in some embodiments, the average aspect ratio is usually preferably 2.50 or less, and may be 2.0 or less, or 1.70 or less. good. The technique disclosed herein can also be suitably carried out in an embodiment in which the average aspect ratio of the abrasive grains is 1.50 or less, further 1.30 or less. Here, the average aspect ratio of the abrasive grains means the average value of the major axis / minor axis ratios of the individual particles constituting the abrasive grains, that is, the number average aspect ratio. Hereinafter, unless otherwise specified, the average aspect ratio in the present specification means the above-mentioned number average aspect ratio.

The number average aspect ratio of the abrasive grains is measured by, for example, the following method. That is, using a scanning electron microscope (SEM), a predetermined number of particles contained in the abrasive grains to be measured are observed in an SEM image containing 100 or more particles in one field of view. Observation is performed at an observation magnification of 10,000 to 50,000 times. The abrasive grains to be measured may be one kind of abrasive grain particles or a mixture of two or more kinds of abrasive grain particles. For the abrasive grain particles in the SEM image, draw the smallest rectangle circumscribing each particle image. The length of the long side of the rectangle is the value of the major axis, the length of the short side is the value of the minor axis, and the value obtained by dividing the value of the major axis by the value of the minor axis for each particle is calculated as the aspect ratio. That is, the aspect ratio of each particle is obtained as the ratio of the long side / short side of the smallest rectangle circumscribing the particle. The number average aspect ratio can be obtained by arithmetically averaging the aspect ratios of the predetermined number of particles. The number aspect ratio can be obtained by using general image analysis software.
The predetermined number of particles, that is, the number of particles for which the aspect ratio of each particle is calculated, is usually preferably 100 or more from the viewpoint of improving measurement accuracy and reproducibility, and may be 500 or more. preferable. The upper limit of the predetermined number is not particularly limited. From the viewpoint of measurement efficiency, the predetermined number may be, for example, 5000 or less, or 2500 or less.

The silica particles contained in the abrasive grains may be various silica particles containing silica as a main component. Here, the silica particles containing silica as a main component refer to particles in which 90% by weight or more, usually 95% by weight or more, typically 98% by weight or more of the particles are silica. Examples of the silica particles that can be used include, but are not limited to, colloidal silica, precipitated silica, sodium silicate silica, alkoxide silica, fumed silica, dried silica, explosive silica and the like. Further examples of the silica particles that can be used include silica particles obtained by using the silica particles as a raw material. Examples of such silica particles include heat treatment such as heating, drying, and firing, pressure treatment such as autoclave treatment, crushing, crushing, etc., on silica particles of the above raw material (hereinafter, also referred to as “raw material silica”). Silica particles obtained by applying one or more treatments selected from the mechanical treatment, surface modification, etc. of the above may be contained. Examples of the surface modification include introduction of a functional group and chemical modification such as metal modification. The abrasive grains in the technique disclosed herein may include one of such silica particles alone or in combination of two or more.

Colloidal silica is mentioned as a preferable example of silica particles that can be used as a constituent component of silica abrasive grains in the technique disclosed herein. Among them, it is preferable to use colloidal silica synthesized through particle growth in the aqueous phase, such as sodium silicate silica and alkoxide silica. With silica abrasive grains containing this type of colloidal silica, high polishing rates and good surface accuracy can be suitably achieved. When the silica abrasive grains disclosed herein contain colloidal silica, the colloidal silica contained in the silica abrasive grains may be one kind or two or more kinds having different production conditions and / or physical properties. .. Further, the silica abrasive grains may be composed of one kind or two or more kinds of colloidal silica, and may be composed of a combination of colloidal silica and other silica particles, that is, silica particles other than colloidal silica. May be good. In a preferred embodiment, the abrasive grains contained in the polishing composition contain colloidal silica alone. By using colloidal silica alone, better surface accuracy (eg, surface with reduced waviness) can be achieved while maintaining a high polishing rate.

The particle shape of colloidal silica is not particularly limited, and may be spherical or non-spherical, for example. Specific examples of the non-spherical shape include a peanut shape, a cocoon shape, a protrusiond shape, a rugby ball shape, and the like. The peanut shape can be, for example, the shape of a peanut shell. The shape with protrusions can be, for example, a konpeito shape.

As another example of silica particles, for example, silica particles obtained by subjecting raw material silica to heat treatment (hereinafter, also referred to as “heat-treated silica”), specifically heated silica particles, and dried silica. Examples include particles, calcined silica particles, and the like. Here, the heated silica particles are typically obtained through a treatment of holding them in an environment of 60 ° C. or higher and lower than 110 ° C. for a certain period of time or longer, for example, 15 minutes or longer, typically 30 minutes or longer. Silica particles. Further, the dried silica particles are typically in an environment of 110 ° C. or higher and lower than 500 ° C., preferably 300 ° C. or higher and lower than 500 ° C. for a certain period of time or longer, for example, 15 minutes or longer, typically 30 minutes or longer. Silica particles obtained through a holding process. The calcined silica particles (hereinafter, also referred to as “calcined silica”) are typically in an environment of 500 ° C. or higher, preferably 700 ° C. or higher, more preferably 900 ° C. or higher for a certain period of time or longer, for example, 15. Silica particles obtained through a treatment of holding for a minute or more, typically 30 minutes or more. The silica particles obtained through the process of heat-treating any of the above-mentioned raw material silicas, that is, precipitated silica, sodium silicate silica, alkoxide silica, fumed silica, dried silica, explosive silica and the like, are referred to herein. This is a typical example included in the concept of heat-treated silica. When the silica abrasive grains contain heat-treated silica, the heat-treated silica contained in the silica abrasive grains may be one kind or two or more kinds having different production conditions and / or physical properties. Further, the silica particles may be composed of one or more types of heat-treated silica, or may be composed of a combination of heat-treated silica and other silica particles, that is, silica particles that have not been heat-treated. good.

The technique disclosed herein can also be carried out in an embodiment in which the abrasive grains contained in the polishing composition contain heat-treated silica alone or in combination of heat-treated silica and other silica particles. As described above, in the embodiment in which the silica abrasive grains contain at least the heat-treated silica, the content of the heat-treated silica in the silica abrasive grains is not particularly limited. The technique disclosed herein can also be preferably carried out in an embodiment in which the silica abrasive grains contained in the polishing composition include heat-treated silica and colloidal silica in combination. By using colloidal silica in addition to heat-treated silica, higher surface accuracy can be achieved.

The polishing composition disclosed herein may contain particles other than silica particles as the abrasive particles having the average secondary particle diameter. As the particles other than the silica particles, any of inorganic particles, organic particles, and organic-inorganic composite particles can be used. Specific examples of the inorganic particles include oxide particles such as alumina particles, cerium oxide particles, chromium oxide particles, titanium dioxide particles, zirconium oxide particles, magnesium oxide particles, manganese dioxide particles, zinc oxide particles, and red iron oxide particles; silicon nitride particles. , Nitride particles such as boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; carbonates such as calcium carbonate and barium carbonate; and the like. Examples of the alumina particles include α-alumina, intermediate alumina other than α-alumina, and composites thereof. Intermediate alumina is a general term for alumina particles other than α-alumina, and specific examples thereof include γ-alumina, δ-alumina, θ-alumina, η-alumina, κ-alumina, and composites thereof. Specific examples of the organic particles include polymethylmethacrylate (PMMA) particles, poly (meth) acrylic acid particles, polyacrylonitrile particles, and the like. Here, (meth) acrylic acid has the meaning of comprehensively referring to acrylic acid and methacrylic acid. As the particles other than the silica particles, one kind may be used alone or two or more kinds may be used in combination.

In the polishing composition disclosed herein, the content of silica particles in the solid content contained in the polishing composition is not particularly limited. The content of the silica particles is preferably 40% by weight or more, more preferably 50% by weight or more, still more preferably 60% by weight or more, from the viewpoint of facilitating the effect of the present invention. , Even more preferably 80% by weight or more, particularly preferably 90% by weight or more, for example 99% by weight or more. In the present specification, the solid content contained in the polishing composition means a residual content after evaporating water from the polishing composition at a temperature at which the bound water is not removed, for example, 60 ° C., that is, a non-volatile content. ..

The polishing composition disclosed herein can be preferably carried out in a manner substantially free of alumina particles. Examples of the alumina particles include α-alumina particles. According to such a polishing composition, quality deterioration due to the use of alumina particles is prevented. Examples of the quality deterioration referred to here include generation of scratches and dents, residual alumina, and piercing defects of abrasive grains. In the present specification, it is more preferable that the ratio of the abrasive grains to the total amount of solids contained in the polishing composition is 1% by weight or less, that the predetermined abrasive grains, for example, alumina particles are not substantially contained. It means that it is 0.5% by weight or less, typically 0.1% by weight or less. A polishing composition in which the proportion of alumina particles is 0% by weight, that is, a polishing composition containing no alumina particles is particularly preferable. Further, the polishing composition disclosed herein can be preferably carried out in a manner substantially free of α-alumina particles.

The polishing composition disclosed herein can also be preferably carried out in an embodiment that does not substantially contain particles other than silica particles, that is, non-silica particles. Here, "substantially free of non-silica particles" means that the proportion of non-silica particles in the total amount of solids contained in the polishing composition is 1% by weight or less, more preferably 0.5% by weight or less, which is typical. Means that it is 0.1% by weight or less. In such an embodiment, the application effect of the technique disclosed herein can be suitably exerted.

The content of the abrasive grains in the polishing composition is not particularly limited, but is typically 0.1% by weight or more, preferably 0.5% by weight or more, and more preferably 1% by weight or more. It is preferably 3% by weight or more, more preferably 5% by weight or more, and particularly preferably 5% by weight or more. When a plurality of types of abrasive grains are contained, the above-mentioned content is the total content thereof. Higher polishing rates tend to be achieved by increasing the content of abrasive grains. From the viewpoint of the surface smoothness of the substrate after polishing and the stability of polishing, the content is usually preferably 30% by weight or less, preferably 25% by weight or less, more preferably 15% by weight or less, still more preferably. Is 10% by weight or less.

(water)
The polishing composition disclosed herein typically contains, in addition to the abrasive grains as described above, water in which the abrasive grains are dispersed. As the water, ion-exchanged water, pure water, ultrapure water, distilled water and the like can be preferably used. The ion-exchanged water can typically be deionized water.

The polishing composition disclosed herein can be preferably carried out, for example, in a form having a solid content of 0.5% by weight to 30.0% by weight. The form in which the solid content is 1.0% by weight to 20.0% by weight is more preferable. The polishing composition can typically be a slurry composition.

(acid)
The polishing composition disclosed herein is carried out in an embodiment containing an acid as a polishing accelerator. The acid that can be used is not particularly limited as long as the sodium hydroxide amount α required to raise the pH of the polishing composition by 1.0 satisfies the above range, and either an inorganic acid or an organic acid can be used. Is. Examples of the organic acid include organic carboxylic acids having 1 to 18 carbon atoms, typically 1 to 10 carbon atoms, organic phosphonic acids, organic sulfonic acids, amino acids and the like. The acid may be used alone or in combination of two or more.

Specific examples of the inorganic acid include phosphoric acid (ortrinic acid), nitrate, sulfuric acid, hydrochloric acid, boric acid, sulfamic acid, phosphinic acid, phosphonic acid, pyrophosphate, tripolyphosphate, tetrapolyphosphate, hexametaphosphate, carbonic acid, and fluoride. Hydrogenic acid, sulfite, thiosulfate, chloric acid, perchloric acid, chloric acid, hydroiodic acid, periodic acid, iodic acid, hydrobromic acid, perbromic acid, bromic acid, chromium acid, nitrite, etc. Can be mentioned.

Specific examples of organic acids include citric acid, maleic acid, malic acid, glycolic acid, succinic acid, itaconic acid, malonic acid, iminodic acid, gluconic acid, lactic acid, mandelic acid, tartaric acid, formic acid, acetic acid, propionic acid, Buty acid, adipic acid, oxalic acid, valeric acid, enant acid, caproic acid, capric acid, pelargonic acid, capric acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, cyclohexanecarboxylic acid, phenylacetic acid, benzoic acid , Crotonic acid, oleic acid, linoleic acid, linolenic acid, ricinolenic acid, methacrylic acid, glutaric acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, tarthronic acid, glyceric acid, hydroxybutyric acid, hydroxyacetic acid, hydroxybenzoic acid, Organic carboxylic acids such as salicylic acid, isocitrate, methylenesuccinic acid, galvanic acid, ascorbic acid, nitroacetic acid, oxaloacetic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid; Amino acids such as serine, threonine, cysteine, methionine, phenylalanine, tryptophan, tyrosine, proline, cystine, glutamine, asparagine, lysine, arginine; nicotinic acid; picric acid; picolinic acid; methyl acid phosphate, ethyl acid phosphate, ethyl glycol acid phosphate , Isopropyl acid phosphate, phytic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetra (methylenephosphonic acid), diethylenetriaminepenta (methylenephosphonic acid), ethane-1,1-diphosphon Acid, Etan-1,1,2-triphosphonic acid, Etan-1-hydroxy-1,1-diphosphonic acid, Etanhydroxy-1,1,2-triphosphonic acid, Etan-1,2-dicarboxy-1,2 -Organic such as diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, α-methylphosphonosuccinic acid, aminopoly (methylenephosphonic acid) Phosphoric acid; organic sulfonic acid such as methanesulfonic acid, ethanesulfonic acid, aminoethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 2-naphthalenesulfonic acid, sulfosuccinic acid, 10-camfersulfonic acid, isethionic acid, taurine, etc. Etc. Will be.

Examples of preferable acids from the viewpoint of polishing efficiency include phosphoric acid, phosphonic acid, maleic acid, hydrochloric acid, nitrate, sulfuric acid, sulfamic acid, phytic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, methanesulfonic acid and the like. .. Of these, phosphoric acid, phosphonic acid, maleic acid, hydrochloric acid, nitric acid, and sulfuric acid are preferable.

In a preferred embodiment of the polishing composition disclosed herein, the acid is a first acid (typically a weak acid) P1 and a _second acid P2 ₍ typically more easily dissociated). Is used in combination with (strong acid). By using the first acid P ₁ in combination with the second acid P ₂ which is more easily dissociated in this way, the dissociation of the acid is better suppressed, and the application effect of the technique disclosed herein is more effective. Can be effectively demonstrated. The pKa1 of the _first acid P1 (acid dissociation index of the first stage, 25 ° C.) is not particularly limited, but may be, for example, 1.6 or more and 3.5 or less. In some embodiments, the pKa1 of the _first acid P1 may be, for example, 1.8 or higher, typically 2.0 or higher. Examples of the first acid P ₁ are phosphoric acid, maleic acid, sulfite, chloric acid, nitrite, tripolyphosphate, nicotinic acid, oxaloacetate, chloroacetic acid, phthalic acid, fumaric acid, malonic acid, tartrate acid, and citrus. Examples thereof include acid, polysulfonic acid, glutamic acid, salicylic acid, aspartic acid, glycine, arginine, tyrosine, valine, methionine, lysine and leucine. Of these, phosphoric acid and maleic acid are preferable. The pKa1 of the _second acid P2 (acid dissociation constant of the first stage, 25 ° C.) is not particularly limited as long as it is smaller than the pKa1 of the _first acid P1, but is not particularly limited, but is, for example, -10.0 or more and less than 1.6. Can be. In some embodiments, the pKa1 of the _second acid P2 may be, for example, 1.5 or less, typically 1.2 or less. Examples of the second acid P ₂ are hydrochloric acid, nitrate, sulfuric acid, oxalic acid, pyrophosphate, phosphinic acid, phosphonic acid, picric acid, picolin acid, thiosulfate, chloric acid, perchloric acid, iodine hydride, and excess. Examples thereof include iodine hydride, iodic acid, hydrobromic acid, perbromic acid, bromine acid, chromic acid, nitroacetic acid, trichloroacetic acid, dichloroacetic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid and the like. Of these, hydrochloric acid, nitric acid, sulfuric acid, and phosphonic acid are preferable.

From the viewpoint of better exerting the effect of the combined use of the first acid P ₁ and the _second acid P ₂ , the pKa 1 of the first acid P ₁ is 0. It is preferably 1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. In some embodiments, the pKa1 of the _first acid P1 may be 3 or more greater than the pKa1 of the _second acid P2 and may be 4 or more greater. The difference between pKa1 of the _first acid P1 and pKa1 of the _second acid P2 is preferably 10 or less, more preferably 6 or less, still more preferably 4 or less, and particularly preferably 4. It is 2 or less. In some embodiments, the difference may be, for example, 1 or less, typically 0.8 or less. In a preferred embodiment, the difference between pKa1 of the _first acid P1 and pKa1 of the _second acid P2 can be 3 or more and 10 or less. In another preferred embodiment, the difference between pKa1 of the _first acid P1 and pKa1 of the _second acid P2 can be 0.1 or more and 0.8 or less.

When the first acid P ₁ and the second acid P ₂ are used in combination, the molar concentration X (molar / L) of the first acid P ₁ and the molar concentration Y of the second acid P ₂ in the polishing composition The value (X / Y) of the ratio to (molar / L) is not particularly limited, but is usually 3 or less, preferably 2.5 or less, more preferably 2 or less, still more preferably 1.8 or less, particularly. It is preferably 1.5 or less. By using the first acid P ₁ and the second acid P ₂ in combination so as to have a specific molar ratio, the above-mentioned effects can be more preferably exhibited. In some embodiments, the ratio value (X / Y) may be, for example, 1 or less, typically 0.75 or less. The lower limit of the value (X / Y) of the above ratio is not particularly limited, but is usually 0.1 or more, preferably 0.3 or more, and more preferably 0.5 or more. In the technique disclosed herein, for example, the value (X / Y) of the ratio of the molar concentration X of the first acid P ₁ to the molar concentration Y of the second acid P ₂ in the polishing composition is 0.1 or more. It can be preferably carried out in an embodiment of 3 or less (preferably 0.3 or more and 1.3 or less).

In another preferred embodiment of the polishing composition disclosed herein, the acid is a first acid Q ₁ , a second acid Q ₂ that is more likely to dissociate than the first acid Q ₁ , and a second acid. It is used in combination with a third acid Q ₃ , which is more easily dissociated than the acid Q ₂ . By using three kinds of acids having different easiness of dissociation in combination as described above, the dissociation of the acid is better suppressed, and the application effect of the technique disclosed herein can be more effectively exhibited. The pKa1 of the _first acid Q1 (acid dissociation index of the first stage, 25 ° C.) is not particularly limited, but may be, for example, 2 or more and 3.5 or less. In some embodiments, the pKa1 of the _first acid Q1 may be, for example, 2.1 or higher, and typically 2.15 or higher. Examples of the first acid Q ₁ include phosphoric acid, chloric acid, nitrite, tripolyphosphate, nicotinic acid, oxaloacetic acid, chloroacetic acid, phthalic acid, fumaric acid, malonic acid, tartrate acid, citric acid, polysulfonic acid, Examples thereof include glutamic acid, salicylic acid, glycine, arginine, tyrosine, valine, methionine, lysine, leucine and the like. Of these, phosphoric acid is preferable. The pKa1 of the _second acid Q2 (acid dissociation constant of the first stage, 25 ° C.) may be smaller than the pKa1 of the _first acid Q1 and larger than the pKa1 of the _third acid Q3, in particular. It is not limited, but can be, for example, 1.6 or more and less than 2.0. Examples of the _second acid Q2 include maleic acid, sulfurous acid, aspartic acid and the like. Of these, maleic acid is preferable. The pKa1 of the _third acid Q3 (acid dissociation constant of the first stage, 25 ° C.) is not particularly limited as long as it is smaller than the pKa1 of the _second acid Q2, but is, for example, -10.0 or more and less than 1.6. Can be. In some embodiments, the pKa1 of the _third acid Q3 may be, for example, 1.55 or less, typically 1.5 or less. Examples of the _third acid Q3 are hydrochloric acid, nitrate, sulfuric acid, oxalic acid, pyrophosphate, phosphonic acid, phosphinic acid, picric acid, picolinic acid, thiosulfate, chloric acid, perchloric acid, iodine hydride, and excess. Examples thereof include iodine hydride, iodic acid, hydrobromic acid, perbromic acid, bromine acid, chromic acid, nitroacetic acid, trichloroacetic acid, dichloroacetic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid and the like. Of these, phosphonic acid is preferable.

From the viewpoint of better exerting the effect of the combined use of the first acid Q ₁ , the second acid Q ₂ and the third acid Q ₃ , pKa1 of the first acid Q ₁ is the second acid Q. It is preferably 0.1 or more larger than pKa1 of ₂ , preferably 0.2 or more, and even more preferably 0.3 or more. The difference between pKa1 of the _first acid Q1 and pKa1 of the _second acid Q2 is preferably 10 or less, more preferably 6 or less, still more preferably 4 or less, and particularly preferably 2 or less. Is. Further, the pKa1 of the _second acid Q2 is preferably 0.1 or more larger than the pKa1 of the _third acid Q3, more preferably 0.15 or more, and further preferably 0.2 or more. .. The difference between pKa1 of the _second acid Q2 and pKa1 of the _third acid Q3 is preferably 5 or less, more preferably 3 or less, still more preferably 2 or less, and particularly preferably 1 or less. Is.

When the first acid Q ₁ and the second acid Q ₂ and the third acid Q ₃ are used in combination, the molar concentration S (molar / L) of the first acid Q ₁ and the second acid Q 3 in the polishing composition are the second. The value (S / T) of the ratio of the acid Q ₂ to the molar concentration T (molar / L) is not particularly limited, but is usually 3 or less, preferably 2.5 or less, more preferably 2 or less, still more preferable. Is 1.8 or less, particularly preferably 1.5 or less. The lower limit of the ratio (S / T) is not particularly limited, but is usually 0.1 or more, preferably 0.3 or more, and more preferably 0.5 or more. The above ratio (S / T) may be, for example, 0.8 or more, typically more than 1. Further, the value (T / U) of the ratio of the molar concentration T (mol / L) of the second acid Q ₂ to the molar concentration U (mol / L) of the third acid Q ₃ in the polishing composition is particularly high. Although not limited, it is usually 2.5 or less, preferably 2 or less, and more preferably 1.5 or less. The ratio (T / U) may be, for example, 1.2 or less, typically less than 1. The lower limit of the ratio (T / U) is not particularly limited, but is usually 0.1 or more, preferably 0.3 or more, and more preferably 0.5 or more. By using the first acid Q ₁ , the second acid Q ₂ and the third acid Q ₃ in combination so as to have a specific molar ratio, the above-mentioned effects can be more preferably exhibited.

The acid may be used in the form of a salt of the acid. Examples of the salt include metal salts, ammonium salts, alkanolamine salts and the like of the above-mentioned inorganic acids and organic acids. Examples of the metal salt include alkali metal salts such as lithium salt, sodium salt and potassium salt. Examples of the ammonium salt include quaternary ammonium salts such as tetramethylammonium salt and tetraethylammonium salt. Examples of the alkanolamine salt include monoethanolamine salt, diethanolamine salt, and triethanolamine salt.
Specific examples of the salt include alkali metal phosphates and alkali metals such as tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, trisodium phosphate, disodium hydrogen phosphate, and sodium dihydrogen phosphate. Hydrogen phosphate; Alkali metal salt of organic acid exemplified above; Alkali metal salt of diacetate diacetate, Alkali metal salt of diethylenetriamine pentaacetic acid, Alkali metal salt of hydroxyethylethylenediamine triacetic acid, Triethylenetetraminehexacetic acid Alkali metal salts; etc. The alkali metal in these alkali metal salts can be, for example, lithium, sodium, potassium and the like.

As the salt that can be contained in the polishing composition disclosed herein, a salt of an inorganic acid, for example, an alkali metal salt or an ammonium salt can be preferably adopted. For example, potassium chloride, sodium chloride, ammonium chloride, potassium nitrate, sodium nitrate, ammonium nitrate, potassium phosphate and the like can be preferably used.

The acid and its salt can be used alone or in combination of two or more (eg, two or three). In a preferred embodiment, an acid and a salt of an acid different from the acid can be used in combination. The acid is preferably an inorganic acid. The acid salt is preferably an inorganic acid salt.

The molar concentration of the acid in the polishing composition (or the total molar concentration of the two acids if they are included) is the amount of sodium hydroxide required to raise the pH of the polishing composition by 1.0. There is no particular limitation as long as the above range is satisfied, but it is typically 0.07 mol / L or more, more preferably 0.09 mol / L or more. In some embodiments, the molar concentration of the acid may be, for example, 0.1 mol / L or higher, typically 0.14 mol / L or higher. Higher polishing rates can be achieved by increasing the molar concentration of acid. From the viewpoint of surface accuracy after polishing, polishing stability, etc., the molar concentration of the acid is usually 1.2 mol / L or less, preferably 1 mol / L or less, more preferably 0.8. It is mol / L or less, more preferably 0.7 mol / L or less.

(Oxidant)
The polishing composition disclosed herein contains an oxidizing agent. Examples of oxidizing agents are peroxides, nitrates or salts thereof, perioic acids or salts thereof, peroxo acid or salts thereof, permanganic acid or salts thereof, chromium acid or salts thereof, oxygen acids or salts thereof, metal salts. , Sulfates and the like, but are not limited thereto. The oxidizing agent may be used alone or in combination of two or more. Specific examples of the oxidizing agent include hydrogen peroxide, sodium peroxide, barium peroxide, nitrate, iron nitrate, aluminum nitrate, ammonium nitrate, peroxomonosulfate, ammonium peroxomonosulfate, metal salt peroxo monosulfate, peroxodisulfate, and peroxodisulfuric acid. Ammonium sulfate, peroxodisulfuric acid metal salt, peroxophosphate, peroxosulfate, sodium peroxoborate, pergic acid, peracetic acid, perbenzoic acid, perphthalic acid, hypobromic acid, hypoiodic acid, chloric acid, bromine acid, Iodine acid, periodic acid, perchloric acid, hypochloric acid, sodium hypochlorite, calcium hypochlorite, potassium permanganate, metal chromate salt, metal heavy chromate salt, iron chloride, iron sulfate, Examples thereof include iron citrate and iron ammonium sulfate. Preferred oxidizing agents include hydrogen peroxide, iron nitrate, periodic acid, peroxomonosulfuric acid, peroxodisulfuric acid and nitric acid. It preferably contains at least hydrogen peroxide, and more preferably consists of hydrogen peroxide.

The content of the oxidizing agent in the polishing composition is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, still more preferably 0.3% by weight or more based on the amount of the active ingredient. .. In some embodiments, the content of the oxidant may be, for example, 0.4% by weight or more, typically 0.5% by weight or more. If the content of the oxidant is too small, the rate of oxidizing the object to be polished slows down and the polishing rate decreases, which may be unfavorable for practical use. The content of the oxidizing agent in the polishing composition is preferably 10% by weight or less, more preferably 5% by weight or less, still more preferably 3% by weight or less based on the amount of the active ingredient. In some embodiments, the molar concentration of the oxidant may be, for example, 2% by weight or less, typically 1.5% by weight or less. If the content of the oxidizing agent is too large, the surface accuracy of the object to be polished tends to be lowered, which may be unfavorable for practical use.

(Basic compound)
The polishing composition may contain a basic compound, if necessary. Here, the basic compound refers to a compound having a function of raising the pH of the composition by being added to the polishing composition. Examples of basic compounds include alkali metal hydroxides, carbonates and bicarbonates, quaternary ammonium or salts thereof, ammonia, amines, phosphates and hydrogen phosphates, organic acid salts and the like. The basic compound may be used alone or in combination of two or more.

Specific examples of the alkali metal hydroxide include potassium hydroxide, sodium hydroxide and the like.
Specific examples of the carbonate and the 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 a salt thereof include quaternary ammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, and tetrabutylammonium hydroxide; alkali metals of such quaternary ammonium hydroxides. Salt; etc. Examples of the alkali metal salt include sodium salts and potassium salts.
Specific examples of amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N- (β-aminoethyl) ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, and anhydrous piperazine. , Piperazine hexahydrate, 1- (2-aminoethyl) piperazine, N-methylpiperazine, guanidine, azoles such as imidazole and triazole, and the like.
Specific examples of phosphates and hydrogen phosphate salts include alkalis such as tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, trisodium phosphate, disodium hydrogen phosphate, and sodium dihydrogen phosphate. Metal salts can be mentioned.
Specific examples of the organic acid salt include potassium citrate, potassium oxalate, potassium tartrate, sodium potassium tartrate, ammonium tartrate and the like.

The molar concentration of the basic compound in the polishing composition is preferably about 0.001 mol / L or more, more preferably 0.005 mol / L or more, still more preferably 0.01 mol / L or more. .. In some embodiments, the molar concentration of the basic compound may be, for example, 0.05 mol / L or higher, typically 0.1 mol / L or higher. The molar concentration of the basic compound in the polishing composition is preferably about 5 mol / L or less, more preferably 1 mol / L or less, still more preferably 0.5 mol / L or less.

(Other ingredients)
The polishing composition disclosed herein contains a polishing composition such as a surfactant, a water-soluble polymer, a dispersant, a chelating agent, a preservative, and an antifungal agent, to the extent that the effects of the present invention are not significantly impaired. If necessary, a known additive that can be used for the product may be further contained.

The surfactant is not particularly limited, and any of anionic surfactant, nonionic surfactant, cationic surfactant, and amphoteric surfactant can be used. The use of a surfactant can improve the dispersion stability of the polishing composition. The surfactant may be used alone or in combination of two or more. The surfactant may typically be a water-soluble organic compound having a molecular weight of less than 1 × ¹⁰⁶ .
Specific examples of the anionic surfactant include polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl sulfate ester, alkyl sulfate ester, polyoxyethylene alkyl sulfate, alkyl sulfuric acid, alkylbenzene sulfonic acid, alkyl phosphate ester, and polyoxyethylene. Alkyl phosphate ester, polyoxyethylene sulfosuccinic acid, alkyl sulfosuccinic acid, alkylnaphthalene sulfonic acid, alkyldiphenyl ether disulfonic acid, polyacrylic acid, sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene alkyl ether sulfate, Examples thereof include ammonium polyoxyethylene alkylphenyl ether sulfate, sodium polyoxyethylene alkylphenyl ether sulfate, and salts thereof.
Other specific examples of anionic surfactants include polyalkylaryl sulfonic acid-based compounds such as naphthalene sulfonic acid formaldehyde condensate, methylnaphthalene sulfonic acid formaldehyde condensate, anthracene sulfonic acid formaldehyde condensate, and benzene sulfonic acid formaldehyde condensate. Melamine formalin resin sulfonic acid compound such as melamine sulfonic acid formaldehyde condensate; Lignin sulfonic acid compound such as lignin sulfonic acid and modified lignin sulfonic acid; Aromatic amino sulfonic acid such as aminoaryl sulfonic acid-phenol-formaldehyde condensate Other compounds include polyisoprene sulfonic acid, polyvinyl sulfonic acid, polyallyl sulfonic acid, polyisoamylene sulfonic acid, polystyrene sulfonic acid; and salts thereof. As the salt, alkali metal salts such as sodium salt and potassium salt are preferable.
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. ..
Specific examples of the cationic surfactant include an alkyltrimethylammonium salt, an alkyldimethylammonium salt, an alkylbenzyldimethylammonium salt, an alkylamine salt and the like.
Specific examples of the amphoteric tenside include an alkyl betaine type, a fatty acid amide propyl betaine type, an alkyl imidazole type, an amino acid type, and an alkyl amine oxide type.

In the polishing composition of the embodiment containing a surfactant, it is appropriate that the content of the surfactant is, for example, 0.0005% by weight or more. The content is preferably 0.001% by weight or more, more preferably 0.002% by weight or more, from the viewpoint of surface smoothness after polishing. Further, from the viewpoint of the polishing rate and the like, the content is preferably 3.0% by weight or less, preferably 0.5% by weight or less, for example, 0.1% by weight or less.

The polishing composition disclosed herein may contain a water-soluble polymer. By containing a water-soluble polymer, the surface accuracy after polishing can be improved. Examples of water-soluble polymers include polyalkylarylsulfonic acid-based compounds such as naphthalenesulfonic acid formaldehyde condensate, methylnaphthalenesulfonic acid formaldehyde condensate, and anthracenesulfonic acid formaldehyde; and melamineformalin resin sulfone such as melaminesulfonic acid formaldehyde condensate. Acid-based compounds; Lignin sulfonic acid-based compounds such as lignin sulfonic acid and modified lignin sulfonic acid; Aromatic amino sulfonic acid-based compounds such as aminoaryl sulfonic acid-phenol-formaldehyde condensate; , Polyallyl sulfonic acid, polyisoamylene sulfonic acid, polystyrene sulfonate, polyacrylic acid salt, polyvinyl acetate, polymaleic acid, polyitaconic acid, polyvinyl alcohol, polyglycerin, polyvinylpyrrolidone, isoprene sulfonic acid and acrylic acid Polymers, polyvinylpyrrolidone polyacrylic acid copolymers, polyvinylpyrrolidone vinyl acetate copolymers, diallylamine hydrochloride sulfur dioxide copolymers, carboxymethylcellulose, salts of carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, purulan, chitosan, chitosan salts And so on. The water-soluble polymer may be used alone or in combination of two or more.

In the polishing composition of the embodiment containing the water-soluble polymer, it is appropriate that the content of the water-soluble polymer in the polishing composition is, for example, 0.001% by weight or more. The above-mentioned content is the total content thereof in the embodiment containing a plurality of water-soluble polymers. The content is preferably 0.003% by weight or more, more preferably 0.005% by weight or more, still more preferably 0.007% by weight or more, from the viewpoint of surface smoothness of the object to be polished after polishing. .. Further, from the viewpoint of the polishing rate and the like, the content is preferably 1.0% by weight or less, preferably 0.5% by weight or less, for example 0.1% by weight or less. It should be noted that the technique disclosed herein can be preferably carried out even in an embodiment in which the polishing composition does not substantially contain a water-soluble polymer.

Examples of dispersants are polycarboxylic acid dispersants such as polycarboxylic acid sodium salt and polycarboxylic acid ammonium salt; naphthalene sulfonic acid dispersants such as naphthalene sulfonic acid sodium salt and naphthalene sulfonic acid ammonium salt; alkyl sulfonic acid. Examples include system dispersants; polyphosphate-based dispersants; polyalkylene polyamine-based dispersants; quaternary ammonium-based dispersants; alkylpolyamine-based dispersants; alkylene oxide-based dispersants; polyhydric alcohol ester-based 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-based chelating agents include ethylenediamine tetraacetic acid, sodium ethylenediamine tetraacetate, nitrilotriacetic acid, sodium nitrilotriacetate, ammonium nitrilotriacetic acid, hydroxyethylethylenediamine triacetic acid, sodium hydroxyethylethylenediamine triacetate, and diethylenetriaminepentaacetic acid. , Diethylenetriamine pentaacetate sodium, triethylenetetramine hexaacetic acid and triethylenetetramine hexaacetate sodium. Examples of organic phosphonic acid-based chelating agents include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetrakis (methylenephosphonic acid), and diethylenetriaminepenta (methylenephosphonic acid). Acid), Etan-1,1-diphosphonic acid, Etan-1,1,2-triphosphonic acid, Etan-1-hydroxy-1,1-diphosphonic acid, Etan-1-hydroxy-1,1,2-triphosphonic acid , Etan-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid and α-methylphospho Contains nosuccinic acid. Of these, organic phosphonic acid-based chelating agents are more preferable, and among them, ethylenediaminetetrakis (methylenephosphonic acid) and diethylenetriaminepenta (methylenephosphonic acid) are mentioned. Particularly preferred chelating agents include ethylenediamine tetrakis (methylenephosphonic acid).

Examples of preservatives and fungicides include isothiazolin-based preservatives such as 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one, and paraoxybenzoic acid esters. , Phenoxyethanol and the like.

(Abrasive liquid)
The polishing composition disclosed herein is typically supplied to the object to be polished in the form of a polishing solution containing the composition for polishing and used for polishing the object to be polished. The polishing liquid may be prepared by diluting the polishing composition, for example. Here, the dilution is typically a dilution with water. Alternatively, the polishing composition may be used as it is as a polishing liquid. That is, the concept of the polishing composition in the technique disclosed herein includes a polishing liquid (working slurry) supplied to the polishing object and used for polishing the polishing object, and diluted and used as the polishing liquid. Both with concentrates are included. The polishing composition in the form of such a concentrated liquid is advantageous from the viewpoint of convenience and cost reduction in manufacturing, distribution, storage and the like. The concentration ratio can be, for example, about 1.5 to 50 times. From the viewpoint of storage stability of the concentrated solution, a concentration ratio of usually 2 to 20 times, typically 2 to 10 times is appropriate.

(Composition for multi-dosage form polishing)
The polishing composition disclosed herein may be a one-dosage form or a multi-dosage form including a two-dosage form. For example, a liquid A containing a part of the constituents of the polishing composition, typically a component other than water, and a liquid B containing the remaining components are mixed to polish the object to be polished. It may be configured to be used. The composition for multi-dosage form polishing according to a preferred embodiment is composed of a liquid A containing abrasive grains and a liquid B containing components other than the abrasive grains. The liquid A containing the abrasive grains may further contain a dispersant. Examples of the components other than the abrasive grains contained in the liquid B include acids, water-soluble polymers and other additives. Normally, they are stored separately before use and can be mixed at the time of use. The time of use here can typically be the time of polishing the substrate to be polished. At the time of mixing, an oxidizing agent such as hydrogen peroxide may be further mixed. For example, when the oxidizing agent is supplied in the form of an aqueous solution, the aqueous solution can be the C liquid constituting the multi-dosage polishing composition.

The polishing composition disclosed herein can be preferably applied to polishing, for example, a nickel phosphorus substrate, a glass substrate, a carbon substrate and the like. Further, as the plating material, a disc substrate having a metal layer other than the nickel phosphorus plating layer or a metal compound layer on the surface of the base disk may be used. Above all, it is suitable as a polishing composition for a nickel-phosphorus-plated substrate having a nickel-phosphorus-plated layer on a base disk made of an aluminum alloy. In such applications, it is particularly meaningful to apply the techniques disclosed herein.

The polishing composition disclosed herein is particularly meaningful in applications where high polishing efficiency is required, such as a pre-polishing process in a magnetic disk substrate manufacturing process where a highly accurate surface is required after the finish polishing process. Can be used. When a plurality of pre-polishing steps are provided as a pre-polishing step, it can be used in any of the pre-polishing steps, and the same or different polishing compositions can be used in these pre-polishing steps. The polishing composition disclosed herein is suitable, for example, as a polishing composition used in the primary polishing step of a magnetic disk substrate, that is, the first polishing step. Among them, it can be preferably used in the first polishing step after nickel phosphorus plating, that is, the primary polishing step in the manufacturing process of the nickel phosphorus substrate.

The polishing composition disclosed herein polishes a magnetic disk substrate having a surface roughness of about 20 Å to 300 Å as measured by, for example, a laser scan type surface roughness meter "TMS-3000WRC" manufactured by Schmitt Measurement System Inc. Therefore, it is suitable for the purpose of adjusting the surface roughness of the magnetic disk substrate to 10 Å or less. In such applications, it is particularly meaningful to apply the techniques disclosed herein. The surface roughness referred to here means an arithmetic mean roughness (Ra).

<Polishing process>
The polishing composition disclosed herein can be suitably used for polishing a magnetic disk substrate as an object to be polished, for example, in an embodiment including the following operations. Hereinafter, a preferred embodiment of a method of polishing an object to be polished using the polishing composition disclosed herein will be described. Hereinafter, the object to be polished is also referred to as a substrate to be polished.
That is, a polishing liquid (working slurry) containing any of the polishing compositions disclosed herein is prepared. The preparation of the polishing liquid may include preparing the polishing liquid by subjecting the polishing composition to operations such as concentration adjustment and pH adjustment. Examples of the concentration adjustment include dilution. Alternatively, the polishing composition may be used as it is as a polishing liquid.

Next, the polishing liquid is supplied to the object to be polished and polished by a conventional method. For example, an object to be polished is set in a general polishing device, and a polishing liquid is supplied to the surface of the object to be polished, that is, the surface to be polished through the polishing pad of the polishing device. Typically, while continuously supplying the polishing liquid, the polishing pad is pressed against the surface of the object to be polished to move them relatively. The movement may be, for example, a rotational movement. The polishing of the object to be polished is completed through such a polishing step.

The polishing process as described above can be part of the manufacturing process for magnetic disk substrates, such as nickel phosphorus substrates. Therefore, according to this specification, a method for manufacturing a magnetic disk substrate and a method for polishing including the above-mentioned polishing step are provided.

The polishing composition disclosed herein can be preferably used in a pre-polishing step of the object to be polished, for example, a primary polishing step. According to this specification, there is provided a method for manufacturing a magnetic disk substrate and a method for polishing, which comprises a step of performing pre-polishing using any of the above-mentioned polishing compositions. The above method includes a step (1) of supplying the polishing composition disclosed herein to a magnetic disk substrate to polish an object to be polished. The method may include a finish polishing step after the prepolishing step. The polishing composition used in the finish polishing step is not particularly limited. Therefore, the matters disclosed in this specification include the step (1) of polishing the magnetic disk substrate with the polishing composition containing the abrasive grains disclosed herein, and the polishing composition used in the step (1). A method for manufacturing a magnetic disk substrate and a polishing method including the step (2) of polishing the magnetic disk substrate with a polishing composition different from the above are included in this order. According to such a manufacturing method, a magnetic disk substrate can be efficiently manufactured.

Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in such examples.

<Examples 1 to 26>
[Preparation of polishing composition]
Multiple types of acids were prepared. The polishing composition of Examples 1 to 26 in which one or more of these acids, abrasive grains, 31% hydrogen peroxide solution, and deionized water are mixed and the abrasive grains are contained in a proportion of 6.5% by weight. The thing was prepared. As the abrasive grains, colloidal silica having an average secondary particle diameter of 150 nm was used. The pH of the polishing composition according to each example was adjusted with potassium hydroxide (KOH). Table 1 shows the type and concentration of the acid used in each example, the concentration of the hydrogen peroxide solution, and the pH of the polishing composition. Further, for the polishing composition of each example, the amount of sodium hydroxide α required to raise the pH by 1.0 was calculated by the above-mentioned method. The results are shown in the "NaOH amount α" column of Table 1.

[Abrasion of disc]
The polishing composition according to each example was used as it was in the polishing liquid, and the object to be polished was polished under the following conditions. As the object to be polished, an aluminum substrate for a hard disk having an electroless nickel phosphorus plating layer on the surface was used. The substrate had a diameter of 3.5 inches, an outer diameter of about 95 mm, an inner diameter of about 25 mm, a donut shape, a thickness of 1.75 mm, and a surface roughness Ra before polishing was 130 Å. The surface roughness Ra is the arithmetic mean roughness of the nickel phosphorus-plated layer measured by a laser scan type surface roughness meter "TMS-3000WRC" manufactured by Schmitt Measurement System Inc.

(Polishing conditions)
Polishing equipment: Double-sided polishing machine manufactured by System Seiko Co., Ltd., model "9.5B-5P"
Polishing pad: Polyurethane pad manufactured by FILWEL, trade name "CR200"
Number of substrates to be polished: 15 (3 / carrier x 5 carriers)
Polishing liquid supply rate: 135 mL / min Polishing load: 120 g / cm ²
Upper surface plate rotation speed: 27 rpm
Lower platen rotation speed: 36 rpm
Sun gear (sun gear) rotation speed: 8 rpm
Amount of polishing: Total thickness of about 2.2 μm on both sides of each substrate

[Abrasion rate]
The polishing rate when the substrate to be polished was polished under the above polishing conditions using the polishing composition according to each example was calculated. The polishing rate was determined based on the following formula.
Polishing rate [μm / min] = Weight loss of substrate due to polishing [g] / (Substrate area [cm ² ] x Nickel phosphorus plating density [g / cm ³ ] x Polishing time [min]) x 10 ⁴
The obtained values are converted into relative values when the polishing rate of Example 11 is 100, and are shown in the column of "polishing rate" in Table 1.

[Long wavelength swell]
Using "Optiflat III" manufactured by KLA Tencor (USA), measure the arithmetic mean swell (Wa) value measured under the condition of a cutoff value of 5 mm in a radius of 20 mm to 44 mm from the center of the polished substrate. bottom. The obtained values are converted into relative values when the arithmetic mean swell (Wa) of Example 11 is 100, and are shown in the “waviness” column of Table 1.

[pit]
Using "Optiflat III" manufactured by KLA Tencor (USA), the surface of 10 sheets and 20 surfaces was measured under the condition of a cutoff value of 5 mm in a radius of 20 mm to 44 mm from the center of the polished substrate, and black spots were measured. It was judged whether or not there was a defect in the shape. Here, those with 0-5 defects are evaluated as "○", those with 6-10 defects are evaluated as "△", and those with 10-20 defects are evaluated as "×". bottom. The results are shown in the "Pit" column of Table 1.

[Stability]
The stability of the polishing composition of each example was evaluated. Specifically, for the polishing compositions of each example, those in which no aggregation or precipitation of abrasive grains was observed even after 2 days from the start of static storage at room temperature were marked with "○" for 2 days. Those in which agglomeration or precipitation of abrasive grains was observed by the eye were evaluated as "x". The results are shown in the "Stability" column of Table 1.

As shown in Table 1, the polishing composition of Examples 1 to 10 in which the amount of NaOH α required to raise the pH of the polishing composition by 1.0 is 0.06 mol / L or more and 1 mol / L or less. Better results were obtained at the polishing rate of the product as compared with Examples 11 to 22 in which the amount of NaOH α was less than 0.06 mol / L. Further, the polishing compositions of Examples 1 to 10 have better stability of the polishing composition, and also have waviness and pits, as compared with Examples 23 to 26 in which the NaOH amount α is more than 1 mol / L. It was reduced. From this result, according to the polishing composition in which the amount of NaOH required to raise the pH by 1.0 α is 0.06 mol / L or more and 1 mol / L or less, high quality with reduced waviness and pits. It was confirmed that the surface after polishing can be efficiently realized.

Although specific examples of the present invention have been described in detail above, these are merely examples and do not limit the scope of claims. The techniques described in the claims include various modifications and modifications of the specific examples exemplified above.

Claims (3)

A polishing composition used in the pre-process of the finish polishing process in polishing a magnetic disk substrate.
Contains abrasive grains, acid, oxidizer and water,
The acid comprises a first acid P ₁ and a second acid P ₂ .
The pKa1 of the _first acid P1 is larger than the pKa1 of the _second acid P2 .
The pKa1 of the _second acid P2 is -10.0 or more and 1.2 or less.
The value (X / Y) of the ratio of the molar concentration X (mol / L) of the first acid P ₁ to the molar concentration Y (mol / L) of the second acid P ₂ in the polishing composition is 3 or less,
The abrasive grains contain at least silica particles and contain at least silica particles.
The average secondary particle diameter of the abrasive grains measured by the dynamic scattering method is 50 nm or more and 300 nm or less.
The pH is 1-2,
A polishing composition in which the amount of sodium hydroxide required to raise the pH by 1.0 is 0.06 mol / L or more and 1 mol / L or less. The polishing composition according to claim 1, which comprises colloidal silica as the silica particles. A method for manufacturing a magnetic disk substrate, which comprises a step of polishing the magnetic disk substrate using the polishing composition according to claim 1 or 2 .