JP2020053108A - Composition for polishing and use thereof - Google Patents

Abstract

To provide a composition for polishing having high workability and capable of realizing smoothness of a polishing pad surface at an early stage.SOLUTION: In polishing a magnetic disk substrate, a composition for polishing that is supplied between a polishing pad and a polishing target and is used for polishing the polishing target is provided. The composition for polishing contains silica particles as abrasive grains and water. The silica particles include particles Shaving an aspect ratio of 1.10 or more by SEM image analysis and particles Shaving an aspect ratio of less than 1.10 by SEM image analysis, and a value obtained by dividing a number of the particles Sby a number of the particles Sis from 0.10 to 1.40.SELECTED DRAWING: None

Description

  The present invention relates to a polishing composition, a pad surface conditioning composition, and a method for manufacturing a magnetic disk substrate using the same, and other methods.

  In the manufacture of a magnetic disk substrate, generally, polishing (primary polishing) that emphasizes polishing efficiency (eg, polishing rate) is performed before a final polishing step performed to finish the surface of a final product with high accuracy. . For example, by performing at least primary polishing and final polishing on a disk substrate (Ni-P substrate) on which nickel phosphorus plating has been performed, a highly accurate surface can be efficiently realized. In such polishing, silica abrasive grains can be used from the primary polishing stage for the purpose of obtaining higher surface quality. For example, in the polishing where a high polishing rate is required for productivity, such as the primary polishing of a disk substrate such as a Ni-P substrate, silica abrasive grains having high workability are required in order to achieve both surface quality and polishing rate. The use of is preferred. Patent Document 1 is cited as a prior art document that discloses this type of conventional technology.

JP 2014-116057 A

  Incidentally, the substrate polishing as described above is generally performed using a polishing pad. However, in the initial stage of polishing performed using the polishing pad (also referred to as an initial pad life. For example, in a polishing process including a plurality of batch polishing, In the initial batch polishing.), Polishing for a predetermined period of time (for example, polishing of one batch) tends to produce a substrate that does not reach a target level of surface quality, and thus the yield tends to be low. As one of the main causes, it is conceivable that irregularities of the initial polishing pad surface are transferred to the substrate surface. As one polishing pad undergoes a predetermined (total) polishing time (for example, by repeating the number of batch polishing), the percentage of acceptable products having a desired surface quality is improved, so that the polishing pad surface is polished through polishing. Is considered to be smooth. Therefore, if the polishing pad surface can be smoothed in a shorter time, it is expected that the yield in the early stage of the pad life will be improved. Here, since the workability of the polishing slurry (polishing composition) can act not only on the object to be polished but also on the surface of the polishing pad, it seems that the processing power also contributes to the smoothing of the surface of the polishing pad. It is. However, examinations by the present inventors have revealed that even a polishing slurry having high workability does not necessarily realize early smoothing of the polishing pad surface.

  The present invention has been made in view of the above circumstances, and in a polishing composition using silica abrasive grains, which is easy to obtain a high surface quality, has high workability, and realizes early smoothing of the polishing pad surface. It is an object of the present invention to provide a polishing composition that can be used. Another related object is to provide a method for manufacturing a magnetic disk substrate using the polishing composition and other methods.

According to the present specification, a polishing composition is provided. The polishing composition is supplied between the polishing pad and the object to be polished in the polishing of the magnetic disk substrate, and is used for polishing the object to be polished. Further, the polishing composition contains silica particles as abrasive grains and water. Further, the silica particles include a particle S _HAR having an aspect ratio of 1.10 or more by SEM (scanning electron microscope) image analysis and a particle S _LAR having an aspect ratio of less than 1.10 by SEM image analysis. Including. Here, the value obtained by dividing the number NA of the particles S _HAR by the number NB of the particles S _LAR is 0.10 or more and 1.40 or less.

The polishing composition includes, as silica particles, particles S _HAR having an aspect ratio of 1.10 or more and particles S _LAR having an aspect ratio of less than 1.10. Here, according to the particles S _HAR having relatively low sphericity, the processability tends to be improved. In addition, according to the particles S _LAR having a relatively high sphericity, the smoothing of the polishing pad surface at an early stage can be preferably and easily realized. Therefore, according to the polishing composition containing the particles S _HAR and the particles S _LAR , both high workability and early smoothing of the polishing pad surface are easily achieved. In particular, when the polishing composition contains the above-mentioned particles S _HAR and the above-mentioned silica particles S _{LAR at} a content ratio in a suitable range, the above-mentioned effects are preferably exerted. Specifically, the value (number ratio) obtained by dividing the number NA of the particles S _HAR contained in the polishing composition by the number NB of the silica particles S _LAR contained in the polishing composition is 0.10. According to the polishing composition having a constitution of not less than 1.40 or less, excellent surface quality can be realized, workability is high, and smoothing of the polishing pad surface can be realized at an early stage. When the polishing composition is applied to polishing of a magnetic disk substrate, a substrate having a high-quality surface can be manufactured with high productivity, and the yield can be improved. That is, the above polishing composition is practically significant from the viewpoint of improving the production efficiency and the yield of the magnetic disk substrate.

  In a preferred embodiment of the technology disclosed herein (including a polishing composition, a pad surface conditioning composition, a method of manufacturing a magnetic disk substrate, and other methods; the same applies hereinafter), the silica particles are analyzed by SEM image analysis. Has a volume average particle diameter of 50 to 400 nm. When silica particles having such a particle diameter are used as abrasive grains, they are used for polishing a magnetic disk substrate, so that both high workability and improvement in surface quality can be suitably achieved.

  In a preferred embodiment of the technology disclosed herein, as the silica particles, silica particles S1 having an average aspect ratio of 1.10 or more by SEM image analysis and a volume average particle size of less than 200 nm by SEM image analysis are used. Including. By using the silica particles S1 having a relatively small particle size and a low sphericity, higher processability can be easily obtained.

  In a preferred embodiment of the technology disclosed herein, the silica particles include silica particles S2 having an average aspect ratio of less than 1.10 and less than 200 nm in volume average particle diameter by SEM image analysis. By using the silica particles S2 having a relatively small particle diameter and a high sphericity, early smoothing of the polishing pad surface is more preferably realized.

  In a preferred embodiment of the technology disclosed herein, in addition to the silica particles S1 and / or S2, the silica particles have an average aspect ratio of 1.10 or more by SEM image analysis, and have a volume by SEM image analysis. It further includes silica particles S3 having an average particle diameter of 200 nm or more. By using the silica particles S3 having a relatively large diameter and low sphericity in combination with the silica particles S1 and S2, the polishing pad surface grinding action is improved, and the smoothing of the polishing pad surface at an early stage is preferably realized.

  In a preferred embodiment of the technology disclosed herein, the silica particles include colloidal silica. By using colloidal silica, a high-quality substrate surface can be preferably obtained. Further, the silica particles preferably further include heat-treated silica particles in addition to the colloidal silica. As a result, high surface quality can be realized, and further, high workability and early smoothing of the polishing pad surface can be preferably compatible.

  The content of the silica particles S1, S2, and S3, and the content of colloidal silica and heat-treated silica particles can be determined from SEM image analysis. The same applies to a system using two or more kinds. For example, in a two-combination system containing silica particles S1 and S2, the frequency distribution of the volume average particle diameter by SEM image analysis shows a bimodal or asymmetric peak shape depending on the content ratio. May be unimodal. From among the particles having such a particle size distribution, SEM images are analyzed for a plurality of particles (preferably the number of samples having statistical reliability) having a particle size corresponding to the silica particles S1 and S2, By determining the average aspect ratio, it is possible to determine the presence or absence of each particle.

In a preferred embodiment of the technology disclosed herein (including a polishing composition, a pad surface conditioning composition, a method for manufacturing a magnetic disk substrate, and other methods; the same applies hereinafter), the polishing composition is as follows: characteristics: the standard abrasion test performed by supplying between particular polishing pad the polishing composition and a specific magnetic disk substrate, based on the roughness R _B of the polishing pad surface before the polishing, total from the start of polishing The reduction rate of the roughness _RA of the polishing pad surface after one hour is 15% or more. Since the polishing composition has a polishing pad surface roughness reduction rate of 15% or more in the standard polishing test, smoothing of the polishing pad surface can be achieved at an early stage of the pad life. When the polishing composition is applied to polishing a magnetic disk substrate, the yield of the substrate can be improved.

In the above-described standard polishing test, the reduction ratio of the roughness R _A of the polishing pad surface in total 1 hour after the start of polishing relative to the roughness R _B of the polishing pad surface before the polishing, i.e. the polishing pad surface roughness The reduction rate is given by the following equation:
Polishing pad surface roughness reduction rate _{(%) = (R B -R} A) / R B × 100
Required from. The roughness is a line roughness based on observation and analysis with a laser microscope. A specific method for measuring the reduction rate of the polishing pad surface roughness will be described later.

  The polishing composition disclosed herein is suitable as a polishing composition used in a step before the final polishing step. For example, the polishing composition is suitably used for primary polishing of a magnetic disk substrate. Since the polishing composition disclosed herein has high workability, it is particularly useful to be used in polishing requiring high polishing efficiency such as the above-mentioned primary polishing.

  Further, according to the present specification, there is provided a method including a polishing step using a polishing composition. The method comprises the steps of: setting a polishing pad on a polishing apparatus; and performing a plurality of polishing steps, wherein one polishing step is to perform polishing for one or a group of polishing objects for a predetermined time using the polishing pad. A polishing process consisting of steps. In the polishing process, any one of the polishing compositions disclosed herein is subjected to the polishing from the first polishing step to at least the number of polishing steps in which the surface quality of the polished material after polishing reaches an acceptable level. It is supplied between the pad and the polishing object. According to the above method, the surface of the polishing pad can be smoothed at an early stage, so that a substrate having a high quality surface can be manufactured with high productivity. Further, it is possible to eliminate or improve a decrease in yield due to a decrease in surface quality of the substrate due to a polishing pad surface shape. The above methods include a method for producing a magnetic disk substrate (industrial production method), a method for manufacturing a magnetic disk substrate, a method for polishing the same, and a method for adjusting the surface of a polishing pad.

3 is a graph showing the relationship between the number ratio NA / NB of silica particles contained in the polishing composition according to the example and the undulation value by polishing using the polishing composition.

  Hereinafter, preferred embodiments of the present invention will be described. It should be noted that matters other than matters 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 conventional techniques in the relevant field. The present invention can be implemented based on the contents disclosed in this specification and common technical knowledge in the field.

<Polishing composition>
(Abrasive)
The polishing composition disclosed herein contains silica particles as abrasive grains. The silica particles include particles S _HAR having an aspect ratio of 1.10 or more by SEM image analysis, and particles S _LAR having an aspect ratio of less than 1.10 by SEM image analysis. Here, the silica particles have the following condition (A): a value (number ratio) obtained by dividing the number NA of the particles S _HAR by the number NB of the particles S _LAR is 0.10 or more and 1.40 or less. Satisfy Particle S _HAR has a larger aspect ratio and relatively lower sphericity than particle S _LAR . When silica particles containing such particles S _HAR are used as abrasive grains, workability tends to be improved. Further, the particle S _LAR has a smaller aspect ratio and a relatively higher sphericity than the particle S _HAR . When silica particles containing such particles S _LAR are used as abrasive grains, smoothing of the polishing pad surface is preferably achieved easily. Although the reason is not particularly limited, it is considered that particles having a high sphericity are unlikely to generate vibration during polishing, and are unlikely to cause irregularities on the polishing pad surface due to the vibration. According to the polishing composition in which the particles S _HAR and the particles S _LAR are included in the number ratio of the above condition (A), excellent surface quality can be realized, workability is high, and the polishing pad surface Smoothing can be realized early.

Here, the aspect ratio of the silica particles (which may be particles S _HAR or particles S _LAR ) is measured, for example, by the following method. That is, the particles to be measured are observed using the SEM. For the silica particles in the SEM image, draw the smallest rectangle circumscribing the particle image. The length of the long side of the rectangle is defined as the value of the major axis, the length of the short side is defined as 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 the particles to be measured is calculated as the aspect ratio. That is, the aspect ratio of the particle to be measured is determined as the ratio of the long side / short side of the smallest rectangle circumscribing the particle.

The number ratio of the particles S _HAR having an aspect ratio of 1.10 or more and the particles S _LAR having an aspect ratio of less than 1.10 contained in the polishing composition is measured by, for example, the following method. That is, using a SEM, a predetermined number of silica particles contained in the abrasive grains to be measured are observed in an SEM image including 50 or more particles in one visual field. Observation is performed at a magnification of 10,000 to 50,000 times. The silica particles to be measured may be one type of silica particles or a mixture of two or more types of silica particles. With respect to the silica particles in the SEM image, the aspect ratio of each silica particle is measured by the above-described method, and based on the obtained aspect ratio, it is determined whether each silica particle corresponds to particle S _HAR or particle S _LAR. I do. Thereafter, the numbers of the particles S _HAR and the particles S _{LAR in} the SEM image are counted. The ratio of the number of the obtained particles S _{HAR to} the number of the particles S _LAR is calculated, and this value can be adopted as the number ratio of the particles S _HAR and the particles S _LAR included in the polishing composition. The number ratio can be determined using general image analysis software. The same applies to the embodiments described later.
In addition, the above-mentioned predetermined number, that is, the number of particles for calculating the aspect ratio of each particle is usually appropriate to be 1000 or more, and preferably 1500 or more, from the viewpoint of improving measurement accuracy and reproducibility. 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.

Aspect ratio The aspect ratio the number NA of the particles _{S HAR} is 1.10 or more divided by the number NB of the particles _{S LAR} is less than 1.10 the value (hereinafter, also referred to as NA / NB.), The polishing pad surface From the viewpoint of early smoothing, it is preferably 1.35 or less, more preferably 1.30 or less, and even more preferably 1.28 or less. According to some embodiments, the NA / NB may be 1.20 or less, 1.15 or less, or 1.10 or less. The NA / NB is preferably at least 0.20, more preferably at least 0.25, and even more preferably at least 0.27, from the viewpoint of improving workability. According to some aspects, the NA / NB may be greater than or equal to 0.50, may be greater than or equal to 0.70, and may be greater than or equal to 0.90.

  In the technology disclosed herein, as long as the silica particles contained in the polishing composition satisfy the condition (A), that is, as long as the NA / NB is 0.10 to 1.40, the polishing composition The distribution of the aspect ratio of the silica particles contained in is not particularly limited. For example, as one of the indexes relating to the distribution of the aspect ratio of the silica particles contained in the polishing composition, the average aspect ratio of the silica particles ST having an upper aspect ratio of 3% is mentioned. Here, the average aspect ratio of the silica particles ST having an upper aspect ratio of 3% refers to an aggregate of a number of particles corresponding to 3% of the total number of silica particles in order of increasing aspect ratio among the silica particles included in the polishing composition. Indicates the average aspect ratio of the silica particles ST when the silica particles ST are used.

  According to a preferred embodiment of the technology disclosed herein, the silica particles have an average aspect ratio of the silica particles ST having an upper aspect ratio of 3% of 1% or more by SEM image analysis of 1.10. From the viewpoint of improving processability, the average aspect ratio of the silica particles ST is preferably 1.30 or more, more preferably 1.40 or more, and still more preferably 1.50 or more (eg, 1.60 or more). It is. From the viewpoint of improving the surface quality, the average aspect ratio of the silica particles ST is preferably 2.20 or less, more preferably 2.00 or less, and still more preferably 1.90 or less (eg, 1.85 or less). It is. In some embodiments, the average aspect ratio of the silica particles ST may be 1.80 or less, 1.75 or less, or 1.70 or less.

Here, the average aspect ratio of the silica particles ST having an upper aspect ratio of 3% is measured by, for example, the following method. That is, using a SEM, a predetermined number of silica particles contained in the abrasive grains to be measured are observed in an SEM image including 50 or more particles in one visual field. Observation is performed at a magnification of 10,000 to 50,000 times. The silica particles to be measured may be one type of silica particles or a mixture of two or more types of silica particles. For the predetermined number of silica particles in the SEM image, the aspect ratio of each silica particle is measured, and when the aspect ratios are arranged in descending order, the silica particles included in the range from the large side to 3% of the predetermined number are determined. By arithmetically averaging the respective aspect ratios of the silica particles, the average aspect ratio of the silica particles ST having the upper 3% aspect ratio can be obtained. The average aspect ratio of the silica particles ST can be determined using general image analysis software. The same applies to the embodiments described later.
In addition, the above-mentioned predetermined number, that is, the number of particles for calculating the aspect ratio of each particle is usually appropriate to be 1000 or more, and preferably 1500 or more, from the viewpoint of improving measurement accuracy and reproducibility. 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.

  Although not particularly limited, the number average aspect ratio of the abrasive grains (typically, silica particles) can be, for example, 1.0 or more. In terms of the polishing rate and the like, in some aspects, 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. In some aspects, the average aspect ratio is usually appropriately 2.50 or less, and may be 2.0 or less, or 1.70 or less from the viewpoint of easily and efficiently increasing the surface quality. Good. The technology disclosed herein can be suitably implemented in a mode in which the average aspect ratio of the abrasive grains (typically, silica particles) is 1.50 or less, and further 1.30 or less. Here, the average aspect ratio of the abrasive grains refers to the average value of the ratio of the major axis / minor axis of the individual particles constituting the abrasive grains, that is, the number average aspect ratio. Hereinafter, unless otherwise specified, the average aspect ratio in this specification means the above-mentioned number average aspect ratio.

Here, the average aspect ratio of the silica particles is measured by, for example, the following method. That is, using a SEM, a predetermined number of silica particles contained in the abrasive grains to be measured are observed in an SEM image including 50 or more particles in one visual field. Observation is performed at a magnification of 10,000 to 50,000 times. The silica particles to be measured may be one type of silica particles or a mixture of two or more types of silica particles. For the silica particles in the SEM image, draw the smallest rectangle circumscribing each particle image. The length of the long side of the rectangle is defined as the value of the major axis, the length of the short side is defined as 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 determined as the ratio of the long side / short side of the smallest rectangle circumscribing the particle. The number average aspect ratio can be determined 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.
In addition, the above-mentioned predetermined number, that is, the number of particles for calculating the aspect ratio of each particle is usually appropriate to be 1000 or more, and preferably 1500 or more, from the viewpoint of improving measurement accuracy and reproducibility. 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.

  According to a preferred embodiment of the technology disclosed herein, the silica particles have a volume average particle diameter of about 50 nm or more and 400 nm or less by SEM image analysis. By using particles having such an average particle size as abrasive grains, both workability and surface quality can be achieved. The volume average particle diameter of the silica particles is preferably about 80 nm or more, more preferably about 100 nm or more, further preferably about 110 nm or more, and particularly preferably about 140 nm or more from the viewpoint of processability and the like. The volume average particle diameter may be, for example, about 160 nm or more, or may be about 180 nm or more. In addition, the volume average particle diameter of the silica particles is preferably about 300 nm or less, more preferably about 250 nm or less, further preferably about 200 nm or less, and particularly preferably about 180 nm or less, from the viewpoint of obtaining a surface with high surface quality. The volume average particle diameter may be, for example, about 130 nm or less.

  The value (D90 / D10) obtained by dividing the volume-based cumulative frequency 90% particle diameter (D90) by the SEM image analysis of the silica particles by the cumulative frequency 10% particle diameter (D10) is usually 1.5 or more (for example, 1.8 or more), and preferably 2.0 or more. By using silica particles having a relatively broad distribution of D90 / D10, it is possible to achieve both improvement of surface quality by small-diameter particles and improvement of workability by large-diameter particles. D90 / D10 is preferably about 3.0 or more, more preferably about 4.0 or more, for example, about 5.0 or more (typically 5.5 or more, and more preferably 6.0 or more). Is also good. The upper limit of D90 / D10 is not particularly limited, and from the viewpoint of achieving both surface quality and workability, it is appropriately set to about 10.0 or less, for example, 8.0 or less (typically 7.0 or less). ).

The volume average particle diameter and D90 / D10 by SEM image analysis in this specification are specifically determined by the following method. 1000 or more particles included in the particles to be measured (may be one kind of abrasive particles or a mixture of two or more kinds of abrasive particles), and 50 or more particles in one visual field Observed in SEM image containing particles of The observation magnification is 10,000 to 50,000 times. A value obtained by 4πr ^3/3 from the radius r of the ideal yen (perfect circle) having an area equal to the projected area of each particle image is calculated as the volume of each particle. Here, the volume is calculated by counting particles independently dispersed in the polishing composition as one particle, regardless of whether they are primary particles or secondary particles. By dividing the total volume of the predetermined number of particles by the number, the volume average particle diameter can be determined. Further, a volume-based cumulative distribution curve is derived from the volume of the predetermined number of particles, and D90 / D10 is obtained by dividing the 90% cumulative frequency particle diameter (D90) by the 10% cumulative frequency particle diameter (D10). be able to. The “cumulative frequency 10% particle size” and the “cumulative frequency 90% particle size” mean that the particle size is small in a cumulative volume distribution curve in which the total volume of the particle size distribution of particles obtained on a volume basis is 100%. The particle size at the point where the cumulative volume from the side becomes 10% and 90%, respectively. The volume average particle diameter and D90 / D10 by SEM image analysis can be determined using general image analysis software.

  The average primary particle size of the abrasive grains (typically, silica particles) is not particularly limited, and is preferably 10 nm or more, more preferably 20 nm or more, further 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. From the viewpoint of obtaining a surface with higher surface quality, the average primary particle diameter is preferably 150 nm or less, more preferably 100 nm or less, further preferably 80 nm or less, and particularly preferably 60 nm or less.

In the technology disclosed herein, the average primary particle diameter of abrasive grains (typically, silica particles) refers to an average particle diameter determined 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 calculated from the specific surface area S (m ² / g) measured by the BET method to D1 (nm). ) = (6000 / 2.2) / S. In this formula, 2.2 is the value of the specific gravity of silica, which is the particle diameter of silica. The specific surface area can be measured using, for example, a surface area measuring device manufactured by Micromeritex Co., Ltd., trade name “Flow Sorb II 2300”.

  In a preferred embodiment of the technology disclosed herein, the silica particles include silica particles S1 having an average aspect ratio of 1.10 or more by SEM image analysis and a volume average particle size of less than 200 nm by SEM image analysis. . By using the silica particles S1 having a relatively low sphericity and a relatively small particle size, it is easy to obtain both high workability and high surface quality.

  The average aspect ratio of the silica particles S1 is preferably 1.12 or more, more preferably 1.15 or more, and still more preferably 1.17 or more (for example, 1.18 or more) from the viewpoint of workability and pad surface grinding. . The average aspect ratio is suitably about 2.5 or less, and is preferably about 2.0 or less, more preferably about 1.5 or less, and still more preferably about 1.5 or less from the viewpoint of surface quality and pad surface smoothness. 1.3 or less (for example, 1.25 or less).

  The volume average particle diameter of the silica particles S1 is preferably less than 180 nm, more preferably less than 160 nm (for example, about 150 nm or less) from the viewpoint of surface quality. The volume average particle diameter is suitably about 50 nm or more, and is preferably about 90 nm or more, more preferably about 120 nm or more (for example, about 130 nm or more) from the viewpoint of processability.

  The D90 / D10 of the silica particles S1 is not particularly limited, and is, for example, suitably about 2.0 or more, and is preferably about 2.5 or more, more preferably about 3.0 or more, from the viewpoint of processability and the like. And more preferably about 3.5 or more (for example, 3.8 or more). The D90 / D10 of the silica particles S1 is suitably, for example, about 10.0 or less, and is preferably about 8.0 or less, more preferably about 6.0 or less, and further preferably about 6.0 or less from the viewpoint of surface quality and the like. Preferably it is about 5.0 or less (for example, about 4.5 or less).

  The ratio of the silica particles S1 in the entire silica particles (which may be the whole abrasive grains) is limited as long as the silica particles satisfy the above condition (A), that is, the above NA / NB is 0.10 or more and 1.40 or less. Not done. From the viewpoint of achieving both workability and surface quality, it is appropriate that the ratio of the silica particles S1 to the entire silica particles be about 30% by weight or more, preferably about 50% by weight or more, more preferably about 55% by weight. % By weight, for example, about 60% by weight or more, or about 70% by weight or more (for example, about 75% by weight or more). In consideration of both workability and early smoothing of the pad surface, it is preferable that the silica particles S1 be used in combination with other silica particles (for example, silica particles S2 described later). From such a viewpoint, the ratio of the silica particles S1 to the entire silica particles (which may be the whole abrasive grains) is appropriately set to about 95% by weight or less, preferably about 85% by weight or less, more preferably. Is about 70% by weight or less, more preferably about 65% by weight or less.

  In a preferred embodiment of the technology disclosed herein, the silica particles include silica particles S2 having an average aspect ratio of less than 1.10 by SEM image analysis and a volume average particle size of less than 200 nm by SEM image analysis. . By using the silica particles S2 having a relatively high sphericity and a relatively small particle diameter, early smoothing of the polishing pad surface is preferably realized. Although the reason is not particularly limited, it is considered that particles having a high sphericity are unlikely to generate vibration during polishing, and are unlikely to cause irregularities on the polishing pad surface due to the vibration.

  The average aspect ratio of the silica particles S2 is preferably about 1.08 or less, more preferably about 1.06 or less (for example, less than 1.05) from the viewpoint of early smoothness and surface quality of the pad surface. The average aspect ratio is 1.0 or more, and is preferably 1.02 or more, more preferably 1.03 or more, from the viewpoint of workability and the like.

  The volume average particle diameter of the silica particles S2 is preferably less than 150 nm, more preferably less than 120 nm, and still more preferably less than 100 nm (for example, about 95 nm or less) from the viewpoint of early smoothing and surface quality of the polishing pad surface. Further, the volume average particle diameter is suitably about 30 nm or more, and is preferably about 50 nm or more, more preferably about 70 nm or more (for example, about 80 nm or more) from the viewpoint of processability.

  The D90 / D10 of the silica particles S2 is not particularly limited and is, for example, suitably about 2.0 or more, and is preferably about 2.4 or more from the viewpoint of early smoothing of the polishing pad surface and workability. It is more preferably about 2.8 or more, and still more preferably about 3.2 or more. Although not particularly limited, since the silica particles S2 have a broad distribution as described above, the polishing pad surface grinding action by the large-diameter particles is more effectively exhibited, and the particles having a high sphericity are obtained. It is considered that the smoothing of the polishing pad surface at an early stage is preferably realized in combination with the vibration suppressing action of the polishing pad. The D90 / D10 of the silica particles S2 is suitably, for example, about 10.0 or less, and is preferably about 8.0 or less, more preferably about 5.0 or less, and further preferably about 5.0 or less from the viewpoint of surface quality and the like. It is preferably about 4.5 or less (for example, about 4.0 or less).

  The ratio of the silica particles S2 to the entire silica particles (which may be the entire abrasive grains) is limited as long as the silica particles satisfy the above condition (A), that is, the above NA / NB is 0.10 or more and 1.40 or less. Not done. From the viewpoint of preferably exhibiting an early smoothing effect on the pad surface, the ratio of the silica particles S2 to the entire silica particles may be about 50% by weight or more, for example, about 75% by weight or more. It may be 90% by weight or more (eg, about 99% by weight or more), and typically may be about 100% by weight. The ratio of the silica particles S2 may be, for example, about 90% by weight or less, and when used in combination with other silica particles, the silica particles S2 are preferably used from the viewpoint of better exhibiting the effect of the combined use (for example, improving processability). It is appropriate that the proportion of S2 is about 60% by weight or less, preferably about 50% by weight or less (for example, 45% by weight or less). In the embodiment in which the silica particles S2 are used in combination with other silica particles, the lower limit of the ratio of the silica particles S2 is not particularly limited, and is, for example, suitably about 5% by weight or more, preferably about 10% by weight or more, more preferably about 10% by weight or more. It may be 15% by weight or more, for example, 25% by weight or more (typically about 30% by weight or more).

  In one particularly preferred embodiment, silica particles S1 and silica particles S2 are used in combination. By using the silica particles S1 and the silica particles S2 together, the silica particles can easily satisfy the above condition (A), that is, the above NA / NB of 0.10 to 1.40. In addition, in such a combined system, the silica particles S2 are considered to reduce vibration caused by the silica particles S1 having low sphericity and contribute to early smoothing of the pad surface. The grinding of the polishing pad surface by the silica particles S1 and the improvement of the smoothness of the polishing pad surface by the silica particles S2 act to achieve more excellent effects. The content ratio of the silica particles S1 and S2 is not particularly limited. For example, the content ratio (S1 / S2) of the silica particles S1 to the silica particles S2 is suitably about 1/99 or more, preferably 10/99. It is 90 or more, more preferably 30/70 or more, further preferably 40/60 or more, particularly preferably 50/50 or more, for example, may be 60/40 or more, or may be 70/30 or more. The content ratio (S1 / S2) is suitably, for example, not more than 99/1, preferably not more than 95/5, more preferably not more than 90/10, further preferably not more than 85/15 (for example, 75/25). Below).

  In a preferred embodiment, the silica particles further include silica particles S3 having an average aspect ratio of 1.10 or more by SEM image analysis and a volume average particle diameter of 200 nm or more by SEM image analysis. By including the silica particles S3 having a relatively low sphericity and a relatively large particle diameter, the polishing pad surface grinding action is improved, and early smoothing of the polishing pad surface can be preferably realized. Workability also tends to be improved.

  The average aspect ratio of the silica particles S3 is preferably 1.20 or more, more preferably 1.25 or more, and still more preferably 1.30 or more, from the viewpoints of workability and pad surface grinding. The average aspect ratio is suitably about 2.5 or less, and is preferably about 2.0 or less, more preferably about 1.5 or less (for example, 1.4 or less) from the viewpoint of surface quality and the like. .

  The volume average particle diameter of the silica particles S3 is preferably about 250 nm or more, more preferably about 300 nm or more, and still more preferably about 350 nm or more, from the viewpoint of grinding and workability of the polishing pad surface. The volume average particle diameter is set so as not to exceed the upper limit of 400 nm of the volume average particle diameter of the whole silica particles. From the viewpoint of surface quality and the like, the volume average particle diameter is suitably about 1,000 nm or less, preferably about 700 nm or less, more preferably about 600 nm or less (for example, about 500 nm or less).

  The D90 / D10 of the silica particles S3 is not particularly limited, and is suitably, for example, about 1.5 or more, and is preferably about 1.8 or more, more preferably about 2.0 or more from the viewpoint of processability and the like. It is. Further, the D90 / D10 of the silica particles S3 is suitably, for example, about 10.0 or less, and is preferably about 5.0 or less, more preferably about 3.0 or less (for example, from the viewpoint of surface quality and the like). About 2.8 or less).

  The silica particles S3 are preferably used in combination with other silica particles (for example, silica particles S1 and S2) from the viewpoint of early smoothing of the pad surface and compatibility between workability and surface quality. In a particularly preferred embodiment, the silica particles S3 are used in combination with the silica particles S1 and S2. By using the silica particle S3 together with the silica particle S1 and the silica particle S2, the silica particle can easily satisfy the above condition (A), that is, the above NA / NB of 0.10 or more and 1.40 or less. From such a viewpoint, the ratio of the silica particles S3 to the entire silica particles (which may be the whole abrasive grains) is appropriately set to about 20% by weight or less, preferably about 15% by weight or less, more preferably. Is about 10% by weight or less, more preferably about 7% by weight or less (for example, about 5% by weight or less). In addition, from the viewpoint that the effect of using the silica particles S3 can be preferably obtained, the ratio of the silica particles S3 to the entire silica particles (which can be the entire abrasive grains) is appropriately about 0.1% by weight or more. It is preferably about 1% by weight or more, more preferably about 2% by weight or more (for example, about 3% by weight or more).

  The silica particles (including any of the silica particles S1, S2, and S3; the same applies hereinafter unless otherwise specified) may be various types of 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, and typically 98% by weight or more of the particles are silica. Examples of the silica particles that can be used include, but are not particularly limited to, colloidal silica, precipitated silica, sodium silicate silica, alkoxide silica, fumed silica, dried silica, explosive silica, and the like. Further, silica particles obtained using the above silica particles as a raw material can also be used. Examples of such silica particles include the above-mentioned raw material silica particles (hereinafter also referred to as “raw silica”), heat treatment such as heating, drying and baking, pressure treatment such as autoclave treatment, crushing and pulverization, and the like. And silica particles obtained by applying one or more treatments selected from mechanical treatment, surface modification and the like. Examples of the surface modification include chemical modification such as functional group introduction and metal modification. The abrasive in the technology disclosed herein may include one kind of such silica particles alone or in combination of two or more kinds.

  Colloidal silica is a preferred example of silica particles that can be used as a component of abrasive grains. Among them, it is preferable to use colloidal silica synthesized through particle growth in an aqueous phase, such as sodium silicate silica and alkoxide silica. According to this type of silica abrasive containing colloidal silica, a high polishing rate and good surface quality 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 type, or may be two or more types having different production conditions and / or physical properties. . Further, the silica abrasive grains may be composed of one 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. Is also good. In one embodiment, the abrasive grains contained in the polishing composition contain colloidal silica alone. By using colloidal silica alone, better surface quality (for example, a surface with reduced waviness) can be realized while maintaining a high polishing rate. Although not particularly limited, the silica particles S1 and S2 are preferably colloidal silica.

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

  Other examples of the silica particles include, for example, silica particles obtained by performing a heat treatment on raw silica (hereinafter, also referred to as “heat-treated silica”), specifically, heated silica particles, and dried silica. Particles, calcined silica particles and the like. Here, the heated silica particles are typically obtained through a process of maintaining the environment at 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 used in an environment of 110 ° C. or more and less than 500 ° C., preferably 300 ° C. or more and less than 500 ° C. for a given time or more, for example, 15 minutes or more, typically 30 minutes or more. This refers to silica particles obtained through a holding process. Then, the calcined silica particles (hereinafter also referred to as “calcined silica”) are typically 500 ° C. or more, preferably 700 ° C. or more, more preferably 900 ° C. or more for a certain time or more, for example, 15 ° C. This refers to silica particles obtained through a treatment for holding for at least 30 minutes, typically for at least 30 minutes. Silica particles obtained through a process of heat-treating any of the raw material silicas described above, that is, precipitated silica, sodium silicate method silica, alkoxide method silica, fumed silica, dried silica, explosive method silica, etc., are referred to herein. It 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 heat-treated silicas, 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. Although not particularly limited, the silica particles S3 are preferably heat-treated silica (typically calcined silica).

  The technology disclosed herein can also be implemented in an embodiment in which the abrasive grains contained in the polishing composition include heat-treated silica alone or a combination of heat-treated silica and other silica particles. In a preferred embodiment, the silica particles contained in the polishing composition include a combination of colloidal silica and heat-treated silica. By further including heat-treated silica particles in addition to colloidal silica, high surface quality can be realized, and high workability and early smoothing of the polishing pad surface can be preferably realized.

  In an embodiment in which the silica particles include colloidal silica and heat-treated silica, the content ratio is not particularly limited. From the viewpoint of early smoothing of the pad surface and compatibility between workability and surface quality, the ratio of the heat-treated silica to 100 parts by weight of the colloidal silica is appropriately set to about 20 parts by weight or less, preferably about 15 parts by weight. Parts by weight, more preferably about 10 parts by weight or less, still more preferably about 7 parts by weight or less (for example, about 5 parts by weight or less). In addition, from the viewpoint that the effect of using the heat-treated silica can be preferably obtained, the ratio of the heat-treated silica to 100 parts by weight of the colloidal silica is appropriately about 0.1 part by weight or more, preferably about 1 part by weight or more, more preferably. Is about 2 parts by weight or more (for example, about 3 parts by weight or more).

  The polishing composition disclosed herein may contain particles other than the silica particles. As particles other than 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. And 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; 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 include γ-alumina, δ-alumina, θ-alumina, η-alumina, κ-alumina, and composites thereof. Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles, poly (meth) acrylic acid particles, and polyacrylonitrile particles. Here, (meth) acrylic acid means acrylic acid and methacrylic acid comprehensively. These particles other than silica particles can be used alone or in combination of two or more.

  In the polishing composition disclosed herein, the content of the silica particles in the solid content of 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, further preferably, from the viewpoint of easily exerting the effects of the technology disclosed herein, from the viewpoint of facilitating the effect of the technology disclosed herein. It is at least 60% by weight, even more preferably at least 80% by weight, particularly preferably at least 90% by weight, for example at least 99% by weight. In the present specification, the solid content contained in the polishing composition refers to a residue after evaporating water from the polishing composition at a temperature at which bound water is not removed, for example, 60 ° C., that is, a non-volatile content. .

  The polishing composition disclosed herein can be preferably implemented in a mode 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 include scratches and depressions, residual alumina, and piercing defects of abrasive grains. In the present specification, the phrase "contains substantially no predetermined abrasive grains, for example, alumina particles" means that the proportion of the abrasive grains is 1% by weight or less, more preferably the total solid content contained in the polishing composition. It means 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 preferred. In addition, the polishing composition disclosed herein can be preferably implemented in a mode substantially free of α-alumina particles.

  The polishing composition disclosed herein can also be preferably practiced in a mode substantially free of particles other than silica particles, that is, non-silica particles. Here, the phrase "substantially free of non-silica particles" means that the proportion of non-silica particles in the total solid content of the polishing composition is 1% by weight or less, more preferably 0.5% by weight or less, typically. Means 0.1% by weight or less. In such an embodiment, the application effects of the technology disclosed herein can be suitably exhibited.

  The content of abrasive grains (typically, silica particles) 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. %, More preferably 3% by weight or more, even more preferably 5% by weight or more. When a plurality of types of abrasive grains are contained, the content is the total content of the abrasive grains. Increasing the abrasive content tends to provide higher workability. From the viewpoint of the surface smoothness of the substrate after polishing and the stability of polishing, usually, the content is suitably 30% by weight or less, preferably 25% by weight or less, more preferably 15% by weight or less, and still more preferably. Is 10% by weight or less.

(water)
The polishing composition disclosed herein typically contains, in addition to the abrasive grains described above, water for dispersing the abrasive grains. As the water, ion exchange water, pure water, ultrapure water, distilled water and the like can be preferably used. The ion exchange water can typically be deionized water.

  The polishing composition disclosed herein can be preferably implemented, for example, in a form having a solid content of 0.5% by weight to 30.0% by weight. More preferably, the solid content is 1.0% to 20.0% by weight. The polishing composition may typically be a slurry composition.

(acid)
The polishing composition disclosed herein preferably contains an acid as a polishing accelerator. As the acid, any of an inorganic acid and an organic acid can be used. Examples of the organic acid include an organic carboxylic acid, an organic phosphonic acid, an organic sulfonic acid, an amino acid and the like having about 1 to 18 carbon atoms, typically about 1 to 10 carbon atoms. The acids can be used alone or in combination of two or more.

  Specific examples of the inorganic acids include phosphoric acid (orthophosphoric acid), nitric acid, sulfuric acid, hydrochloric acid, boric acid, sulfamic acid, phosphinic acid, phosphonic acid, pyrophosphoric acid, tripolyphosphoric acid, tetrapolyphosphoric acid, hexapolyphosphoric acid, carbonic acid, fluoride Hydrogen acid, sulfurous acid, thiosulfuric acid, chloric acid, perchloric acid, chlorous acid, hydroiodic acid, periodic acid, iodic acid, hydrobromic acid, perbronic acid, bromic acid, chromic acid, nitrous acid, etc. No.

  Specific examples of organic acids 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, formic acid, acetic acid, propionic acid, Butyric acid, adipic acid, oxalic acid, valeric acid, enanthic acid, caproic acid, caprylic 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, tartronic acid, glyceric acid, hydroxybutyric acid, hydroxyacetic acid, hydroxybenzoic acid, Salicylic acid, isocitric acid, methylene succinic acid, gallic acid, Organic carboxylic acids such as scorbic acid, nitroacetic acid, oxaloacetic acid, chloroacetic acid, dichloroacetic acid, and trichloroacetic acid; glycine, alanine, glutamic acid, aspartic acid, valine, leucine, isoleucine, serine, threonine, cysteine, methionine, phenylalanine, tryptophan, Amino acids such as 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), diethylene Amine penta (methylene phosphonic acid), ethane-1,1-diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethanehydroxy-1,1,2-triphosphonic acid Acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2,3,4-tricarboxylic acid, α-methyl Organic phosphonic acids such as phosphonosuccinic acid and aminopoly (methylene phosphonic acid); methanesulfonic acid, ethanesulfonic acid, aminoethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, 2-naphthalenesulfonic acid, sulfosuccinic acid, 10 -Organic sulfonic acids such as camphorsulfonic acid, isethionic acid, and taurine; It is.

  Preferred acids from the viewpoint of polishing efficiency include phosphoric acid, phosphonic acid, maleic acid, hydrochloric acid, nitric acid, 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 preferred.

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

  As a 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 used. For example, potassium chloride, sodium chloride, ammonium chloride, potassium nitrate, sodium nitrate, ammonium nitrate, potassium phosphate and the like can be preferably used.

  The acids and salts thereof can be used alone or in combination of two or more (for example, 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 a salt of an inorganic acid.

  When the polishing composition contains an acid, the molar concentration of the acid in the polishing composition (when plural kinds of acids are contained, the total molar concentration thereof) is not particularly limited. For example, about 0.001 mol / L. It is appropriate that the amount is at least about 0.01 mol / L, more preferably at least about 0.05 mol / L, even more preferably at least 0.07 mol / L, particularly preferably at least 0.09 mol / L. / L or more. In some embodiments, the molarity of the acid may be, for example, 0.1 mol / L or more, and typically 0.12 mol / L or more. Higher polishing rates can be achieved by increasing the molarity of the acid. From the viewpoint of the surface quality after polishing and the stability of polishing, the molar concentration of the acid is usually about 1.2 mol / L or less, preferably about 1 mol / L or less, more preferably about 1 mol / L or less. 0.8 mol / L or less, more preferably about 0.7 mol / L or less, particularly preferably about 0.6 mol / L or less (for example, 0.5 mol / L or less).

(Oxidant)
The polishing composition disclosed herein can contain an oxidizing agent. Examples of the oxidizing agent include peroxide, nitric acid or a salt thereof, periodic acid or a salt thereof, peroxo acid or a salt thereof, permanganic acid or a salt thereof, chromic acid or a salt thereof, oxyacid or a salt thereof, and metal salts. , Sulfuric acids and the like, but are not limited thereto. The oxidizing agents can be used alone or in combination of two or more. Specific examples of the oxidizing agent include hydrogen peroxide, sodium peroxide, barium peroxide, nitric acid, iron nitrate, aluminum nitrate, ammonium nitrate, peroxomonosulfuric acid, ammonium peroxomonosulfate, metal salts of peroxomonosulfate, peroxodisulfuric acid, and peroxodisulfide. Ammonium sulfate, metal peroxodisulfate, peroxophosphoric acid, peroxosulfuric acid, sodium peroxoborate, formic acid, peracetic acid, perbenzoic acid, perphthalic acid, hypobromite, hypoiodic acid, chloric acid, bromate, Iodic acid, periodic acid, perchloric acid, hypochlorous acid, sodium hypochlorite, calcium hypochlorite, potassium permanganate, metal chromate, metal dichromate, iron chloride, iron sulfate, Examples 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.

  When the polishing liquid contains an oxidizing agent, the content of the oxidizing agent is preferably 0.05 mol / L or more, more preferably 0.1 mol / L or more, and further preferably 0.15 mol / L. L or more. If the content of the oxidizing agent is too small, the rate of oxidizing the object to be polished becomes slow, and the polishing rate decreases, which may not be practically preferable. When an oxidizing agent is contained in the polishing composition, the content is preferably 1 mol / L or less, more preferably 0.9 mol / L or less, and still more preferably 0.8 mol / L. It is as follows. If the content of the oxidizing agent is too large, the surface accuracy of the object to be polished is likely to decrease, which may not be practically preferable.

(Basic compound)
The polishing composition may contain a basic compound as necessary. Here, the basic compound refers to a compound having a function of increasing the pH of the polishing composition when added to the polishing composition. Examples of the basic compound include alkali metal hydroxides, carbonates and bicarbonates, quaternary ammonium or its salts, ammonia, amines, phosphates and hydrogen phosphates, and organic acid salts. The basic compounds can 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 carbonates and hydrogen carbonates 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 Salts; and the like. Examples of the alkali metal salt include a sodium salt and a potassium salt.
Specific examples of the amine 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 phosphates include alkali salts such as tripotassium phosphate, dipotassium hydrogen phosphate, potassium dihydrogen phosphate, trisodium phosphate, disodium hydrogen phosphate, and sodium dihydrogen phosphate. Metal salts.
Specific examples of the organic acid salt include potassium citrate, potassium oxalate, potassium tartrate, potassium sodium tartrate, ammonium tartrate and the like.

(Other components)
The polishing composition disclosed herein is a polishing composition such as a surfactant, a water-soluble polymer, a dispersant, a chelating agent, a preservative, and a fungicide, as long as the effects of the present invention are not significantly impaired. Known additives that can be used for the product may be further contained as necessary.

The surfactant is not particularly limited, and any of anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants can be used. The use of the surfactant can improve the dispersion stability of the polishing composition. One type of surfactant can be used alone, or two or more types can be used in combination. The surfactant can typically be a water-soluble organic compound having a molecular weight of less than 1 × 10 ⁶ .
Specific examples of the anionic surfactant include polyoxyethylene alkyl ether acetic acid, polyoxyethylene alkyl sulfate, alkyl sulfate, polyoxyethylene alkyl sulfate, alkyl sulfate, alkylbenzene sulfonic acid, alkyl phosphate, polyoxyethylene. Alkyl phosphate ester, polyoxyethylene sulfosuccinic acid, alkyl sulfosuccinic acid, alkyl naphthalene sulfonic acid, alkyl diphenyl ether disulfonic acid, polyacrylic acid, sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium polyoxyethylene alkyl ether sulfate, Ammonium polyoxyethylene alkyl phenyl ether sulfate, polyoxyethylene alkyl phenyl ether sulfate Sodium, and salts thereof.
Other specific examples of anionic surfactants include polyalkylaryl sulfonic acid compounds such as naphthalene sulfonic acid formaldehyde condensate, methyl naphthalene sulfonic acid formaldehyde condensate, anthracene sulfonic acid formaldehyde condensate, and benzene sulfonic acid formaldehyde condensate Melamine formalin resin sulfonic acid compounds such as melamine sulfonic acid formaldehyde condensate; lignin sulfonic acid compounds such as lignin sulfonic acid and modified lignin sulfonic acid; aromatic amino sulfonic acids such as aminoaryl sulfonic acid-phenol-formaldehyde condensate Polyisoprenesulfonic acid, polyvinylsulfonic acid, polyallylsulfonic acid, polyisoamylenesulfonic acid, polystyrenesulfonic acid; and the like. Etc. The. As the salt, an alkali metal salt such as a sodium salt and a potassium salt is 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, and alkyl alkanolamide. .
Specific examples of the cationic surfactant include an alkyltrimethylammonium salt, an alkyldimethylammonium salt, an alkylbenzyldimethylammonium salt, and an alkylamine salt.
Specific examples of the amphoteric surfactant include an alkyl betaine type, a fatty acid amide propyl betaine type, an alkyl imidazole type, an amino acid type, an alkyl amine oxide type and the like.

  In a polishing composition containing a surfactant, the content of the surfactant is suitably, 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 the smoothness of the surface after polishing. From the viewpoint of the polishing rate and the like, the content is suitably at most 3.0% by weight, preferably at most 0.5% by weight, for example, at most 0.1% by weight.

  The polishing composition disclosed herein may contain a water-soluble polymer. By including a water-soluble polymer, the surface quality after polishing can be improved. Examples of the water-soluble polymer include polyalkylarylsulfonic acid compounds such as naphthalenesulfonic acid formaldehyde condensate, methylnaphthalenesulfonic acid formaldehyde condensate and anthracenesulfonic acid formaldehyde; melamine formalin resin sulfone such as melaminesulfonic acid formaldehyde condensate Acid compounds; Lignin sulfonic acid compounds such as lignin sulfonic acid and modified lignin sulfonic acid; Aromatic amino sulfonic acid compounds such as aminoaryl sulfonic acid-phenol-formaldehyde condensate; others, polyisoprene sulfonic acid and polyvinyl sulfonic acid , Polyallylsulfonic acid, polyisoamylenesulfonic acid, polystyrenesulfonic acid salt, polyacrylate, polyvinyl acetate, polymaleic acid, polyitaconic acid, polyvinyl Alcohol, polyglycerin, polyvinylpyrrolidone, copolymer of isoprenesulfonic acid and acrylic acid, polyvinylpyrrolidone polyacrylic acid copolymer, polyvinylpyrrolidone vinyl acetate copolymer, diallylamine hydrochloride sulfur dioxide copolymer, carboxymethylcellulose, carboxymethylcellulose , Hydroxyethylcellulose, hydroxypropylcellulose, pullulan, chitosan, chitosan salts and the like. The water-soluble polymers can be used alone or in combination of two or more.

  In the polishing composition of the embodiment containing a water-soluble polymer, the content of the water-soluble polymer in the polishing composition is suitably, for example, 0.001% by weight or more. In the embodiment containing a plurality of water-soluble polymers, the content is the total content thereof. The content is preferably 0.003% by weight or more, more preferably 0.005% by weight or more, and still more preferably 0.007% by weight or more, from the viewpoint of the surface smoothness of the object to be polished after polishing. . Further, from the viewpoint of the polishing rate and the like, the content is suitably 1.0% by weight or less, preferably 0.5% by weight or less, for example, 0.1% by weight or less. The technology disclosed herein can be preferably implemented even in a mode in which the polishing composition does not substantially contain a water-soluble polymer.

  Examples of dispersants include polycarboxylic acid-based dispersants such as sodium polycarboxylate and ammonium polycarboxylate; naphthalenesulfonic acid-based dispersants such as sodium naphthalenesulfonic acid and ammonium naphthalenesulfonic acid; alkylsulfonic acid Dispersants; polyphosphoric acid dispersants; polyalkylene polyamine dispersants; quaternary ammonium dispersants; alkyl polyamine dispersants; alkylene oxide dispersants; polyhydric alcohol ester dispersants;

  Examples of the chelating agent include an aminocarboxylic acid-based chelating agent and an organic phosphonic acid-based chelating agent. Examples of aminocarboxylic acid-based chelating agents include ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetate, nitrilotriacetic acid, sodium nitrilotriacetate, ammonium nitrilotriacetate, hydroxyethylethylenediaminetriacetic acid, sodium hydroxyethylethylenediaminetriacetate, and diethylenetriaminepentaacetic acid. , Sodium diethylene triamine pentaacetate, triethylene tetramine hexaacetic acid and sodium triethylene tetramine hexaacetate. Examples of the organic phosphonic acid chelating agent include 2-aminoethylphosphonic acid, 1-hydroxyethylidene-1,1-diphosphonic acid, aminotri (methylenephosphonic acid), ethylenediaminetetrakis (methylenephosphonic acid), and diethylenetriaminepenta (methylenephosphonic 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-methylphosphonic acid Includes nosuccinic acid. Of these, organic phosphonic acid-based chelating agents are more preferred, and particularly preferred are ethylenediaminetetrakis (methylenephosphonic acid) and diethylenetriaminepenta (methylenephosphonic acid). Particularly preferred chelating agents include ethylenediaminetetrakis (methylenephosphonic acid).

  Examples of preservatives and fungicides include isothiazoline preservatives such as 2-methyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, and paraoxybenzoates. Phenoxyethanol and the like.

(PH)
The pH of the polishing composition disclosed herein is not particularly limited. The pH of the polishing composition may be, for example, 12.0 or less, typically 0.5 to 12.0, and may be 10.0 or less, typically 0.5 to 10.0. Good. From the viewpoints of polishing rate, surface quality, and the like, the pH of the polishing composition can be 7.0 or less, for example, 0.5 to 7.0, and can be 5.0 or less, typically 1.0 to 1.0. It is more preferably set to 5.0, more preferably 4.0 or less, for example, 1.0 to 4.0. The pH of the polishing composition is, for example, 3.0 or less, typically 1.0 to 3.0, preferably 1.0 to 2.0, and more preferably 1.0 to 1.8. it can. If necessary, a pH adjuster such as an organic acid, an inorganic acid, or a basic compound can be contained so that the above-mentioned pH is realized in the polishing liquid. The above pH can be preferably applied, for example, 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.

(Polishing pad surface roughness reduction rate)
In a preferred embodiment of the polishing composition disclosed herein, a polishing pad surface roughness reduction rate in a standard polishing test is 5% or more (more preferably 10% or more, further preferably 15% or more). As a result, the surface of the polishing pad can be smoothed at an early stage in the early stage of the pad life. The roughness reduction rate is preferably about 20% or more, more preferably about 25% or more, further preferably about 30% or more, and particularly preferably about 35% or more (for example, about 40% or more). The upper limit of the roughness reduction rate is theoretically 100%, and may be, for example, about 70% or less (typically, about 50% or less).

  The polishing pad surface roughness reduction rate is measured from a standard polishing test in which a polishing composition to be evaluated is supplied between a specific polishing pad and a specific magnetic disk substrate using a polishing machine. As the polishing machine, a known or commonly used single-side polishing machine is used. For example, a single-side polishing apparatus manufactured by Nippon Engis Co., Ltd., model “EJ-380IN” can be used. As the polishing pad, a commercially available suede type polishing pad made of polyurethane and having an initial surface line roughness of 10 μm or more (typically 10 μm or more and 15 μm or less, more specifically about 12 to 13 μm) is used. The initial surface line roughness is measured by a method described later. The polishing pad may be one that is adjusted by polishing or the like so as to have the initial surface line roughness. As the suede-type polyurethane polishing pad, a polyurethane pad manufactured by FILWEL, trade name “CR200” can be used. Such a suede-type polyurethane polishing pad has a pore size (opening diameter) of about 10 to 100 μm (for example, 30 to 70 μm, typically about 50 μm). The magnetic disk substrate (substrate to be polished) is a hard disk aluminum substrate (3.5 inch in diameter, about 95 mm in outer diameter and about 25 mm in inner diameter) having an electroless nickel phosphorus plating layer on its surface, Is 1.27 mm and the surface roughness Ra before polishing is 130 °. In addition, the said surface roughness Ra is arithmetic mean roughness of the nickel phosphorus plating layer measured by the laser scanning type surface roughness meter "TMS-3000WRC" by Schmitt Measurement System Inc.

Specific polishing conditions in the standard polishing test can be as follows.
(Polishing conditions)
Polishing device: Single-side polishing device manufactured by Nippon Engis Co., Ltd., model “EJ-380IN” (platen outer diameter: diameter 370 mm)
Polishing pad: suede type polyurethane pad manufactured by FILWEL (for example, product name "CR200")
Number of substrates to be polished: 1 Position of rotation center of substrate to be polished (disk): Disk rotation center is set at 110 mm from the center of the platen.
Polishing pressure: 120 g / cm ²
Supply rate of polishing composition: 9 mL / min. Number of revolutions of platen: 60 revolutions / min. Total polishing time: 1 hour. In addition, in one hour, which is the total polishing time, a predetermined value is considered in consideration of the thickness of the nickel phosphorus plating layer. The substrate to be polished may be replaced at time intervals (for example, at intervals of 5 to 20 minutes). In this case, the total polishing time for those substrates is set to one hour.
In the examples described later, the measurement is performed in the same manner.

The polishing pad surface roughness (surface line roughness) before polishing and one hour after the start of polishing is measured by the following method. In the examples described later, the measurement is performed in the same manner.
(Line roughness measurement method)
The processing surface of the polishing pad (the surface of the pad facing the processing surface of the substrate to be polished (the surface to be polished) (typically, the pad surface in contact with the processing surface of the substrate to be polished) is cut out at three places. A bird's-eye view image is observed at a measurement magnification of 200 times using a laser microscope. The measurement is performed once for each of the three cut-out portions. Specifically, using analysis software, a line segment length of 500 μm is selected as a measurement point, and the line roughness [μm] is calculated from a virtual two-dimensional profile. The number of measurements (N) is 90 points (30 points × 3), and the average value is recorded as the surface line roughness [μm] of the polishing pad.

The polishing composition disclosed herein may satisfy the property of reducing the surface roughness _RA of the polishing pad after the standard polishing test to about 10 μm or less. The roughness _RA of the polishing pad surface after the standard polishing test is preferably about 9.5 μm or less, more preferably about 8.5 μm or less, for example, may be about 7.5 μm or less. According to the polishing composition that satisfies such characteristics, the surface of the polishing pad can be smoothed at an early stage. The lower limit of the roughness _RA of the polishing pad surface after the standard polishing test is about 1 μm or more, and may be about 5 μm or more (for example, about 6 μm or more).

(Polishing liquid)
The polishing composition disclosed herein is typically supplied to a polishing target in the form of a polishing liquid containing the polishing composition, and used for polishing the polishing target. The polishing liquid may be, for example, one prepared by diluting a polishing composition. 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 technology disclosed herein includes a polishing liquid (working slurry) supplied to an object to be polished and used for polishing the object to be polished, and used as a polishing liquid after dilution. Both concentrates are included. Such a polishing composition in the form of a concentrated solution is advantageous from the viewpoints of convenience, cost reduction, and the like during production, distribution, storage, and the like. The concentration ratio can be, for example, about 1.5 to 50 times. From the viewpoint of the storage stability of the concentrate, a concentration ratio of usually about 2 to 20 times, typically about 2 to 10 times is appropriate.

(Multi-component polishing composition)
Note that the polishing composition disclosed herein may be a single-pack type or a multi-pack type including a two-pack type. For example, the components of the polishing composition, typically Part A containing some of the components other than water, and Part B containing the remaining components are mixed to polish the polishing object. It may be configured to be used. The multi-part polishing composition according to a preferred embodiment is composed of Part A containing abrasive grains and Part B containing components other than abrasive grains. Part A including the abrasive grains may further include a dispersant. Components other than the abrasive grains included in Part B include, for example, acids, water-soluble polymers, and other additives. Usually, they are stored separately before use and can be mixed at the time of use. The use time here can be typically the time of polishing a 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 Part C of the multi-part 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 a plating material, a disk substrate provided with a metal layer or a metal compound layer other than the nickel phosphorus plating layer on the surface of the base disk may be used. Among them, it is suitable as a polishing composition for a nickel-phosphorus-plated substrate having a nickel-phosphorus plating layer on a base disk made of an aluminum alloy. In such an application, it is particularly significant to apply the technology disclosed herein.

  The polishing composition disclosed herein is particularly significant in applications where high polishing efficiency is required, such as a preliminary polishing step in a manufacturing process of a magnetic disk substrate that requires a highly accurate surface after the final polishing step. Can be used. When a plurality of pre-polishing steps are provided as a pre-step of the final polishing step, the pre-polishing step can be used, 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 a primary polishing step of a magnetic disk substrate, that is, an initial polishing step. Above all, it can be preferably used in a first polishing step after nickel phosphorus plating, that is, a primary polishing step in a nickel phosphorus substrate manufacturing process.

  The polishing composition disclosed herein, for example, polish a magnetic disk substrate having a surface roughness of about 20 ° to 300 ° measured by a laser scanning type surface roughness meter “TMS-3000WRC” manufactured by Schmitt Measurement System Inc. Thus, the magnetic disk substrate is suitable for adjusting the surface roughness to 10 ° or less. In such an application, it is particularly significant to apply the technology disclosed herein. Here, the surface roughness refers to the arithmetic average roughness (Ra).

<Composition for pad surface adjustment>
In one aspect of the technology disclosed herein, a pad surface conditioning composition is provided. The pad surface adjusting composition is used to adjust (break-in) the polishing pad surface (the surface facing the polishing target surface of the polishing target). In a preferred embodiment, the pad surface conditioning composition has a polishing pad surface roughness reduction rate of 5% or more (more preferably 10% or more, further preferably 15% or more). By using the pad surface conditioning composition disclosed herein, the polishing pad surface can be smoothed at an early stage, so that the target substrate surface quality can be preferably achieved from a relatively early stage of the pad life. A possible polishing pad surface condition can be created. Therefore, in a polishing step performed by supplying a polishing liquid thereafter, a polishing composition different from the polishing composition disclosed herein (typically, a conventionally known polishing composition) is used as the polishing liquid. A substrate having a target surface quality can be manufactured with high productivity, and the yield can be improved by using the structure. The pad surface conditioning composition is also referred to as a pad break-in composition.

  The pad surface conditioning composition disclosed herein may include, but is not limited to, any one of inorganic particles, organic particles, and organic-inorganic composite particles. Specific examples of the inorganic particles include oxide particles such as alumina particles, silica 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; Nitride particles such as silicon nitride particles and boron nitride particles; carbide particles such as silicon carbide particles and boron carbide particles; diamond particles; and carbonates such as calcium carbonate and barium carbonate. 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 include γ-alumina, δ-alumina, θ-alumina, η-alumina, κ-alumina, and composites thereof. Specific examples of the organic particles include polymethyl methacrylate (PMMA) particles, poly (meth) acrylic acid particles, and polyacrylonitrile particles. Here, (meth) acrylic acid means acrylic acid and methacrylic acid comprehensively. These particles can be used alone or in combination of two or more.

A pad surface conditioning composition according to a preferred embodiment includes particles S _HAR containing silica particles and water and having an aspect ratio of 1.10 or more as determined by SEM image analysis, and an average aspect ratio determined by SEM image analysis. Contains less than 1.10 particles S _LAR . The content of the particles S _HAR and the particles S _{LAR in} the pad surface conditioning composition is not particularly limited. For example, the number NA of the particles S _{HAR having} an aspect ratio of 1.10 or more is set to the particle S having an aspect ratio of less than 1.10. divided by the number NB of _LAR (number ratio) is preferably 0.10 to 1.40. The number ratio is preferably 1.35 or less, more preferably 1.30 or less, and even more preferably 1.28 or less, from the viewpoint of smoothing the pad surface. According to some embodiments, the number ratio may be 1.20 or less, 1.15 or less, or 1.10 or less. In addition, the number ratio is preferably 0.20 or more, more preferably 0.25 or more, further preferably 0.27 or more, from the viewpoint of pad surface grinding or the like. According to some aspects, the number ratio may be greater than or equal to 0.50, greater than or equal to 0.70, or greater than or equal to 0.90.

  Other items related to the pad surface conditioning composition are the same as those of the polishing composition, and the items described in the section of the polishing composition can be applied without limitation. Therefore, the overlapping description will not be repeated.

<Polishing method>
The polishing composition disclosed herein can be suitably used for polishing using a magnetic disk substrate as an object to be polished, for example, in a mode including the following operation. Hereinafter, a preferred embodiment of a method for 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. Preparing the polishing liquid may include preparing the polishing liquid by performing operations such as concentration adjustment and pH adjustment on the polishing composition. 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 apparatus, and a polishing liquid is supplied to the surface of the object to be polished, that is, the surface to be polished, through a polishing pad of the polishing apparatus. Typically, while continuously supplying the polishing liquid, a polishing pad is pressed against the surface of the object to be polished to relatively move the two. The movement may be, for example, a rotational movement. Through such a polishing step, polishing of the object to be polished is completed.

  One embodiment of the above polishing method will be described in detail. One embodiment of the technology disclosed herein includes a step of setting a polishing pad on the polishing apparatus. Specifically, a polishing pad is set on a polishing platen of a polishing apparatus. The setting of the polishing pad may be performed at an appropriate timing before and after setting the polishing object. The polishing pad that can be used is not particularly limited. For example, a polishing pad of a hard foamed polyurethane type, a nonwoven fabric type, a suede type, or the like can be used. The suede type may be a buff pad, typically a polishing pad in a non-buff state in which the surface is not buffed (a so-called non-buff pad). Such a suede-type polishing pad (typically, a polishing pad made of polyurethane) is excellent in workability and can easily realize high quality of the substrate surface. The polishing pad surface roughness reduction by the polishing composition and the pad surface conditioning composition disclosed herein is preferably exerted by a suede-type polishing pad, but the effects thereof are the polishing pad surface grinding and the vibration of abrasive grains. Since it is based on the mechanical action of reduction, the type of polishing pad is not limited as long as the action can be exerted. Note that the polishing pad used in the technology disclosed herein does not contain abrasive grains.

  The polishing is typically performed by using a polishing pad set in a polishing apparatus, and includes a plurality of polishing steps in which polishing for a predetermined time performed on one or a group of polishing objects is defined as one polishing step. May be a step included in the polishing process performed. Here, the group of objects to be polished refers to a group of objects to be polished which are set in the polishing apparatus in a state where they can be polished at the same time, and the number of objects to be polished is determined by the configuration and size of the polishing apparatus. In one polishing step, a mode in which two or more polishing objects are polished simultaneously is also referred to as batch polishing. The polishing time in one polishing step is determined by the type of the object to be polished, the target surface quality, and the like. Therefore, the above-mentioned “predetermined time” is not limited to a specific range. Although not particularly limited, in the primary polishing of the Ni-P substrate, polishing is performed for about 1 to 30 minutes (for example, about 3 to 20 minutes) in one polishing step.

  In a polishing process according to a preferred embodiment, from the first polishing step (for example, the first batch) to at least the number of polishing steps (which may be the number of batches) at which the surface quality of the polished material after polishing reaches an acceptable level. The composition for pad surface adjustment disclosed herein is supplied between a polishing pad and an object to be polished. In another preferred embodiment, the polishing composition disclosed herein is supplied in place of the pad surface conditioning composition. As a result, the surface of the polishing pad is smoothed at an early stage, and a surface state of the polishing pad that can achieve a target substrate surface quality can be suitably created from a relatively early stage of the pad life. In addition, a substrate having a target surface quality can be manufactured with high productivity by the subsequent polishing, and the yield can be improved.

In the above polishing process, the supply of a composition selected from the polishing composition and the pad surface conditioning composition disclosed herein between the polishing pad and the object to be polished is at least about 1 hour on a pad life basis. For example, it may be about 2 hours or more, about 5 hours or more, or about 10 hours or more (eg, about 20 hours or more). Also, the supply of the pad surface conditioning composition between the polishing pad and the object to be polished can be made less than 20 hours, and less than 15 hours (for example, 5 hours) in view of the pad surface early smoothing effect. Less). In the embodiment using the polishing composition disclosed herein, in the polishing process, the polishing composition can be used throughout the entire pad life.
In this specification, “pad life” refers to a cumulative polishing time (total polishing time) from the start of polishing performed using one polishing pad.

  In the embodiment using the pad surface conditioning composition, after the polishing step (for example, batch polishing) the number of times that the surface quality of the polished material after polishing reaches a pass level, the polishing composition disclosed herein, or Using a polishing composition different from the polishing composition disclosed herein (typically, a conventionally known polishing composition), a polishing process including a subsequent polishing step (for example, batch polishing) ) Can be implemented. In that case, the composition of the polishing composition and the composition of the pad surface conditioning composition disclosed herein may be the same or different.

  In a mode in which a polishing process including a plurality of polishing steps is performed, a rinsing step and a cleaning step may be included before and after each polishing step, or may not be included. As described later, when the primary polishing step and the final polishing step are performed by the same polishing apparatus, one polishing step may include a primary polishing step and a final polishing step.

  In the polishing method disclosed herein, the polishing apparatus used in the above-described polishing step of supplying and polishing a pad surface conditioning composition or a polishing composition on the same platen simultaneously polishes both surfaces of a polishing object. It may be a double-side polishing apparatus for polishing, or a single-side polishing apparatus for polishing only one side of an object to be polished. When the polishing step is a preliminary polishing step, in some embodiments, a double-side polishing apparatus can be preferably employed as a polishing apparatus for performing the polishing step. When the finish polishing step is performed after the primary polishing step, a single-side polishing apparatus can be preferably used as the polishing apparatus for performing the finish polishing step. In these polishing apparatuses, the number of platens provided in each polishing apparatus may be one or two or more. Each polishing apparatus may be a single-wafer polishing apparatus configured to polish one polishing object at a time, and is configured to be capable of simultaneously polishing a plurality of polishing objects on the same platen. A batch type polishing apparatus may be used.

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

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

  The method for polishing a magnetic disk substrate described above may be a method for adjusting the surface of a polishing pad for a portion using the pad surface adjusting composition. In addition, the technique disclosed herein can be a method of manufacturing a magnetic disk substrate by polishing a plurality of polishing objects like batch polishing, and thus is also a method of manufacturing a magnetic disk substrate (industrial production method). obtain.

  Hereinafter, some examples of the present invention will be described, but the present invention is not intended to be limited to those shown in the examples. In the following description, “%” is based on weight unless otherwise specified.

<Examples 1 to 11>
Silica particles HK shown in Table 1 were mixed with phosphoric acid, 31% hydrogen peroxide solution and deionized water in the weight ratios shown in Table 2 to prepare polishing compositions according to the respective examples. The content of silica particles in the polishing composition was 7%, the content of phosphoric acid was 0.14 mol / L, and the content of hydrogen peroxide was 0.36 mol / L.
The content ratio of abrasive grains in the polishing composition according to each example, the value obtained by dividing the number NA of the particles S _HAR having an aspect ratio of 1.10 or more by the number NB of the particles S _LAR having an aspect ratio of less than 1.10. Table 2 shows NA / NB, average aspect ratio of the silica particles having the top 3% aspect ratio (AR), volume average particle diameter [nm] by SEM image analysis, and reduction rate of polishing pad surface roughness [%].

<Evaluation of undulation, pseudo level difference resolving property and workability>
[Disk polishing]
The polishing composition according to each example was directly used as a polishing liquid, and the object to be polished was polished under the following conditions. As an object to be polished, an aluminum substrate for hard disk (Ni-P substrate) provided with an electroless nickel phosphorus plating layer on the surface was used. The above-mentioned substrate is a donut type having a diameter of 3.5 inches, an outer diameter of about 95 mm, and an inner diameter of about 25 mm, a thickness of 1.27 mm, and a first polishing is performed by setting a removal allowance of 2.2 μm to obtain a surface roughness. A material having a Ra of 3.0 ° was used. In addition, a pseudo step was formed on the surface of the substrate by using an inspection apparatus “Candela OSA7100” manufactured by KLA Tencor for the evaluation of pseudo step resolution. In addition, the said surface roughness Ra is arithmetic mean roughness of the nickel phosphorus plating layer measured by the laser scanning type surface roughness meter "TMS-3000WRC" by Schmitt Measurement System Inc. (the same shall apply hereinafter).

(Polishing conditions)
Polishing device: Single-side polishing device manufactured by Nippon Engis Co., Ltd., model “EJ-380IN” (platen outer diameter: diameter 370 mm)
Polishing pad: suede-type polyurethane pad manufactured by FILWEL, trade name "CR200" Polished for 1 hour under the same polishing conditions using the polishing composition according to each example, that is, the pad life was 1 hour. One used.
Number of substrates to be polished: 1 Position of rotation center of substrate to be polished (disk): Disk rotation center is set at 110 mm from the center of the platen.
Polishing pressure: 120 g / cm ²
Platen rotation speed: 60 rotations / min. Supply rate of polishing composition: 9 mL / min. Polishing amount: 0.45 μm (thickness direction)

[Swell evaluation]
For a substrate polished under the above-mentioned polishing conditions using the polishing composition according to each example (substrate to be polished), a non-contact surface profiler (trade name “NewView5032”, manufactured by Zygo) is used. With an objective lens magnification of 2.5 times and an intermediate lens magnification of 0.5 times, the undulation in the wavelength band of 80 to 500 μm was measured. Four positions were measured at 90 ° intervals at a position 37 mm radially outward from the center of the polished substrate, and the average value was obtained as substrate waviness [Å].
The obtained value was converted to a relative value when the value of Example 8 was set to 100, and is shown in the column of “Waviness” in Table 2. The lower the value, the better the surface quality (flatness). FIG. 1 shows a value NA / NB obtained by dividing the number NA of particles S _HAR having an aspect ratio of 1.10 or more by the number NB of particles S _LAR having an aspect ratio of less than 1.10. And a graph showing the relationship with the swell relative value.

[Evaluation of elimination of pseudo steps]
For a substrate polished under the above-mentioned polishing conditions using the polishing composition according to each example (substrate to be polished), a non-contact surface profiler (trade name “NewView5032”, manufactured by Zygo) is used. The PV (Peak-to-Valley) value was measured in a wavelength band of 10 to 250 μm with a bandpass filter of 10 to 250 μm at an objective lens magnification of 10.0 and an intermediate lens magnification of 1.0. The number of measurements (N) was 24, and the average value was obtained.
The obtained value (average value) was converted to a relative value when the value of Example 8 was set to 100, and is shown in the column of “Pseudo Step Resolvability” in Table 2. The lower the value, the better the step-elimination property.

[Workability evaluation]
The substrate to be polished was polished under the above polishing conditions using the polishing composition according to each example, and the polishing rate at a pad life of one hour was calculated. The polishing rate was determined based on the following formula.
Polishing rate [μm / min] = Amount of weight loss of substrate by polishing [g] / (substrate area [cm ² ] × density of nickel phosphorus plating [g / cm ³ ] × polishing time [min]) × 10 ⁴
The obtained value was converted to a relative value when the polishing rate in Example 8 was set to 100, and is shown in the column of “Processing performance” in Table 2.

As shown in Table 1, the value NA / NB obtained by dividing the number NA of particles S _HAR having an aspect ratio of 1.10 or more by the number NB of particles S _LAR having an aspect ratio of less than 1.10 is 0.10 or more. In Examples 1 to 7 using the polishing composition of 1.40 or less, the reduction rate of the polishing pad surface roughness was 15% or more, and in polishing using a polishing pad having a pad life of 1 hour, undulations and steps were observed. The resolvability improved in both cases. In these examples, silica particles having a volume average particle diameter of 50 to 400 nm are used, and as a result, a workability of 70 or more is shown as a relative value when the polishing rate of Example 8, which is the reference composition, is set to 100. Was. In particular, in Examples 1 to 6 in which a plurality of silica particles (typically, silica particles S1 and S2, and further, silica particles S3) were blended, higher processability was exhibited. Above all, in Examples 3 and 6, which are silica particle blends and have a high polishing pad surface roughness reduction ratio, more excellent surface quality (waviness and step-elimination properties) was exhibited while maintaining high workability. On the other hand, in Examples 8 to 10 where the value NA / NB obtained by dividing the number NA of the particles S _HAR having an aspect ratio of 1.10 or more by the number NB of the particles S _LAR having an aspect ratio of less than 1.10 is greater than 1.40. As compared with Examples 1 to 7, the undulation was large, and the pseudo step-elimination property was poor. Further, in Example 11 using the polishing composition having the above value NA / NB of less than 0.10, the workability was reduced.

  Further, as shown in FIG. 1, a clear correlation was found between the value NA / NB and the swell. Specifically, when the value NA / NB is 0.10 or more and 1.40 or less, high surface quality tends to be obtained.

  As described above, the specific examples of the present invention have been described in detail. However, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and alterations of the specific examples illustrated above.

Claims (10)

In polishing a magnetic disk substrate, a polishing composition used to polish the polishing object supplied between the polishing pad and the polishing object,
Including silica particles and water as abrasive grains,
The silica particles include particles S _HAR having an aspect ratio of 1.10 or more by SEM image analysis, and particles S _LAR having an aspect ratio of less than 1.10 by SEM image analysis,
A polishing composition, wherein a value obtained by dividing the number NA of the particles S _HAR by the number NB of the particles S _LAR is 0.10 or more and 1.40 or less.   The polishing composition according to claim 1, wherein the silica particles have a volume average particle diameter of 50 to 400 nm as determined by SEM image analysis.   3. The polishing slurry according to claim 1, wherein the silica particles include silica particles S <b> 1 having an average aspect ratio of 1.10 or more by SEM image analysis and a volume average particle diameter of less than 200 nm by SEM image analysis. 4. Composition.   The silica particles S2 having an average aspect ratio of less than 1.10 by SEM image analysis and a volume average particle diameter of less than 200 nm by SEM image analysis as the silica particles. 3. The polishing composition according to item 1.   As the silica particles, in addition to the silica particles S1 and / or S2, a silica particle S3 having an average aspect ratio of 1.10 or more by SEM image analysis and a volume average particle diameter of 200 nm or more by SEM image analysis is used. The polishing composition according to any one of claims 1 to 4, further comprising:   The polishing composition according to any one of claims 1 to 5, wherein the silica particles include colloidal silica.   The polishing composition according to claim 6, wherein the silica particles further include heat-treated silica particles in addition to the colloidal silica. The polishing composition in a standard abrasion test performed by supplying between the specific magnetic disk substrate with a particular polishing pad the polishing composition, based on the roughness R _B of the polishing pad surface before the polishing, The polishing composition according to any one of claims 1 to 7, wherein a reduction rate of the roughness _RA of the polishing pad surface after a total of one hour from the start of polishing is 15% or more.   The polishing composition according to any one of claims 1 to 8, which is used in a step before the finish polishing step. Setting a polishing pad on the polishing apparatus;
A polishing process including a plurality of polishing steps, in which one polishing step is to perform polishing for one or a group of polishing objects for a predetermined time using the polishing pad;
Including
The polishing composition according to any one of claims 1 to 9, wherein in the polishing process, from the first polishing step to at least the number of polishing steps at which the surface quality of the polished material after polishing reaches a pass level. Is supplied between the polishing pad and the object to be polished.

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