JP6105916B2 - Cellulose derivative composition, polishing composition using the cellulose derivative composition, method for producing the polishing composition, and method for producing a substrate using the polishing composition - Google Patents

Description

  The present invention relates to a cellulose derivative composition, a polishing composition using the cellulose derivative composition, a method for producing the polishing composition, and a method for producing a substrate using the polishing composition.

  High molecular compounds have various properties such as mechanical properties and thermal properties, which are not found in low molecular weight compounds, and thus are used in a wide range of fields.

  For example, when a polymer compound having a predetermined structure, such as a cellulose derivative, is dissolved in water, the surface tension is reduced, so that excellent wettability is exhibited. Such a polymer compound-containing aqueous solution having wettability is used for applications such as polishing and soldering.

  For example, Patent Document 1 describes a polishing composition comprising a diamine compound (polishing aid) having a predetermined structure, a compound having a polyalkylene glycol structure, and a water-soluble polymer compound. Has been. According to Patent Document 1, it is described that wettability (hydrophilization) is improved by using a water-soluble polymer (and a compound having a polyalkylene glycol structure) together with the polishing aid. Patent Document 1 describes that the polishing composition having high wettability is used for polishing a silicon wafer. Examples of the water-soluble polymer include water-soluble polysaccharides, specifically, hydroxymethyl cellulose, hydroxyethyl cellulose (HEC) and the like.

JP 2011-97050 A

  As described above, the polymer compound-containing aqueous solution can exhibit excellent wettability. However, an aqueous solution containing cellulose derivatives such as hydroxymethyl cellulose and hydroxyethyl cellulose (HEC), which are cited as polymer compounds in Patent Document 1, exists as granular molecules in which the polymer is tightly folded by attractive interaction. . Furthermore, it is considered that there are some in which a plurality of molecules aggregate and exist as the granular molecules. Accordingly, the cellulose derivative in the aqueous solution is not constant in size, and may contain a large amount of cellulose derivative particles having a large particle size as the granular molecules (hereinafter referred to as “cellulose derivative particles having a large particle size”). It has been found that an aqueous solution may not be obtained. Further, it has been found that when an aqueous solution containing a large amount of cellulose derivative particles having a large particle size is used for polishing a substrate, the performance of the polished substrate may be deteriorated.

  Therefore, an object of the present invention is to provide a high-quality cellulose derivative composition in which cellulose derivative particles having a large particle size are not present or hardly exist. Another object of the present invention is to provide a cellulose derivative composition that can be used for polishing a substrate and prevent or reduce defects in the polished substrate.

  The present inventors conducted extensive research. As a result, the inventors have found that the above problem can be solved by setting the number of cellulose derivative particles having a large particle size to a certain value or less, and have completed the present invention.

That is, the present invention is a cellulose derivative composition comprising cellulose derivative particles and water, wherein the number of the cellulose derivative particles having a particle diameter of 10 μm or more is 25 or less per cm ³ .

  According to the present invention, it is possible to provide a high-quality cellulose derivative composition in which cellulose derivative particles having a large particle size are not present or hardly exist.

  According to a particularly preferable embodiment of the present invention, a cellulose derivative composition capable of preventing or reducing defects in a polished substrate can be provided.

  Hereinafter, embodiments for carrying out the present invention will be described in detail.

<Cellulose derivative composition>
According to one embodiment of the present invention, a cellulose derivative composition containing cellulose derivative particles and water is provided. At this time, the number of the cellulose derivative particles having a particle diameter of 10 μm or more is 25 or less per 1 cm ³ . If necessary, a known additive may be further contained.

(Cellulose derivative particles)
The cellulose derivative particle means a cellulose derivative particle in which at least one hydroxyl group of cellulose insoluble in water is substituted with a substituent and becomes water-soluble.

  Cellulose is a polymer in which a large number of β-glucose molecules are polymerized in a linear form by glycosidic bonds, and the structural units of cellulose have hydroxyl groups at the C2, C3, and C6 positions. Since the hydroxyl group forms a strong hydrogen bond within and between molecules, cellulose is generally insoluble in water and organic solvents. However, the cellulose derivative can exhibit water solubility by substituting at least a part of the hydroxyl groups of cellulose with a substituent and cleaving at least a part of the hydrogen bonds.

  The substituent is not particularly limited, and examples thereof include a methyl group, an ethyl group, a hydroxymethyl group, a hydroxyethyl group, a hydroxypropyl group, a carboxymethyl group, and a carboxyethyl group. When cellulose has a plurality of substituents, the respective substituents may be the same or different.

  Specific examples of the cellulose derivative include hydroxymethyl cellulose, hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl cellulose, ethyl hydroxyethyl cellulose, carboxymethyl cellulose and the like. Among these, the cellulose derivative is preferably hydroxyethyl cellulose (HEC) from the viewpoint of imparting wettability. These cellulose derivatives may be used alone or in combination of two or more.

  The weight average molecular weight (in terms of polyethylene oxide) of the cellulose derivative particles is preferably 1,000 or more, preferably 10,000 or more, and more preferably 100,000 or more. When the weight average molecular weight of the cellulose derivative is 1,000 or more, for example, in a polishing application, the hydrophilicity of the surface to be polished is preferably increased.

  The weight average molecular weight (in terms of polyethylene oxide) of the cellulose derivative particles is preferably 2,000,000 or less, more preferably 1,500,000 or less, and 1,000,000 or less. Is more preferably 500,000 or less, and most preferably 300,000 or less. It is preferable that the weight average molecular weight of the cellulose derivative is 2,000,000 or less because, for example, in a polishing application, high dispersion stability is obtained when silica particles or the like are added.

  Although the above-mentioned cellulose derivative particles may be produced by themselves or a commercially available product may be used, it is preferable to use a commercially available product from the viewpoint of cost. As the said commercial item, AL-15, AL-15F, AH-25, SV-25F, CF-G (made by Sumitomo Seika Co., Ltd.), SP200, SP400, EP850, SE400, SE600, EE820 (Daicel Finechem Co., Ltd.) Product), K100 PremiummLV, E4M Premium (manufactured by Dow Chemical Company), and the like. Commercially available cellulose derivative particles are usually produced industrially, and are generally produced through a step of preparing cellulose and a step of converting cellulose to a cellulose derivative.

  The step of preparing the cellulose includes obtaining cellulose from natural raw materials such as wood, wheat straw, sugarcane, waste paper, and cotton. More specifically, a method of preparing pulp from physical, chemical and / or chemical action from wood, wheat straw, sugarcane, waste paper, etc., and obtaining cellulose therefrom; a method of obtaining cellulose from cotton, and the like.

  The step of converting the cellulose into a cellulose derivative includes chemically reacting the cellulose prepared above. Thereby, a cellulose derivative can be manufactured. As the conversion method, a known method can be appropriately used. For example, cellulose can be converted into a cellulose derivative by the following method. That is, a cellulose derivative can be obtained by suspending cellulose in water and adding a base to obtain alkali cellulose (alkali treatment), and then adding a reagent to the cellulose.

  In this case, a known base such as sodium hydroxide or potassium hydroxide can be used as the base.

  Moreover, as the reagent, a reagent capable of obtaining a desired cellulose derivative may be used. For example, when producing hydroxyethyl cellulose (HEC), ethylene oxide or the like is used as a reagent. In the case of producing cellulose acetate, acetic anhydride or the like is used as a reagent. In addition, a catalyst or the like that promotes the reaction can be used as the reagent.

  By appropriately changing the type and amount of base and reagent, reaction temperature, reaction time, and the like, the degree of substitution and weight average molecular weight of the cellulose derivative can be controlled.

  The cellulose derivative obtained by the chemical reaction can be appropriately neutralized with an acid such as phosphoric acid or nitric acid, purified, dried, granulated, or the like.

  By producing a cellulose derivative by the above-described method, a large amount of cellulose derivative can be produced, which is advantageous from the viewpoint of cost. Therefore, the above-mentioned cellulose derivative is preferably a cellulose derivative obtained by alkali treatment of a material derived from a natural raw material, and more preferably a cellulose derivative obtained by alkali treatment of cotton or pulp.

  The content of the cellulose derivative particles is preferably 0.02% by mass or more, more preferably 0.05% by mass or more, and 0.1% by mass or more with respect to the total amount of the cellulose derivative composition. More preferably it is. Further, the content of the cellulose derivative particles is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less based on the total amount of the cellulose derivative composition. preferable. It is preferable that the content of the cellulose derivative is in the above range because the cellulose derivative composition exhibits excellent wettability.

In the cellulose derivative composition of the present invention, the number of cellulose derivative particles having a particle diameter of 10 μm or more is 25 or less per 1 cm ³ . As described above, the cellulose derivative composition of the present invention has no or almost no cellulose derivative particles having a large particle size, and has high quality. The number of cellulose derivative particles having a particle diameter of 10 μm or more is preferably 20 or less per 1 cm ³ , more preferably 15 or less per 1 cm ³ . The lower limit of the number of cellulose derivative particles having a particle diameter of 10 μm or more is 0, but it may be 1 or more.

Further, the number of the cellulose derivative particles having a particle diameter of 10 μm or more and less than 15 μm is preferably 10 or less per 1 cm ³ , more preferably 8 or less per 1 cm ³ , and further preferably 5 or less per 1 cm ^3. It is. The lower limit of the number of the cellulose derivative particles having a particle diameter of 10 μm or more and less than 15 μm is 0, but may be 1 or more.

Further, the number of the cellulose derivative particles having a particle diameter of 15 μm or more is preferably 8 or less per 1 cm ³ , more preferably 6 or less per 1 cm ³ , and further preferably 4 or less per 1 cm ^3. . The lower limit of the number of cellulose derivative particles having a particle diameter of 15 μm or more is 0, but it may be 1 or more.

  In this specification, the particle size (size) and the number of cellulose derivative particles are measured by directly counting the number and size of particles passing through a light shielding type sensor (Sizing Particle Optical Sensing). Method). Specifically, the particle size (size) and the number of cellulose derivative particles can be determined by “Accusizer (registered trademark) FX” manufactured by Particle Sizing Systems, USA. More specifically, the measurement methods described in the examples are employed.

(Known hydrophilic compounds)
The cellulose derivative composition of the present invention may contain other known hydrophilic compounds.

  The known hydrophilic compound is not particularly limited as long as it is other than a cellulose derivative, but an imine derivative such as poly (N-acylalkyleneimine); polyvinyl alcohol; modified (cation modified, anion modified, or nonionic modified) ) Polyvinyl alcohol; polyvinyl pyrrolidone; polyvinyl caprolactam; polyoxyalkylene such as polyoxyethylene; and a copolymer containing these structural units. The form of the copolymer when the hydrophilic compound is a copolymer may be any of a block copolymer, a random copolymer, a graft copolymer, and an alternating copolymer. These known hydrophilic compounds may be used alone or in combination of two or more.

  The weight average molecular weight (in terms of polyethylene oxide) of the known hydrophilic compound is preferably 1,000 or more, more preferably 10,000 or more, further preferably 100,000 or more, 200, It is especially preferable that it is 000 or more. It is preferable that the weight average molecular weight of the known hydrophilic compound is 1000 or more because, for example, in the polishing application, the hydrophilicity of the surface to be polished is increased.

  The weight average molecular weight (in terms of polyethylene oxide) of the known hydrophilic compound is preferably 2,000,000 or less, more preferably 1,500,000 or less, and 1,000,000 or less. More preferably, it is particularly preferably 500,000 or less. It is preferable that the weight average molecular weight of the known hydrophilic compound is 2,000,000 or less because, for example, in a polishing application, high dispersion stability is obtained when silica particles or the like are added.

  The content in the case of including a known hydrophilic compound is preferably less than 50% by mass, more preferably 40% by mass or less, and 1 to 30% by mass with respect to the total mass of the cellulose derivative. More preferably.

(water)
Water serves as a solvent for the cellulose derivative particles. It is preferable that the water contains as little impurities as possible. The water is preferably water from which impurity ions are removed by an ion exchange resin, impurities are removed by a filter, and foreign substances are removed by distillation. Examples of such water include ion exchange water, pure water, ultrapure water, and distilled water.

  The water content is preferably 90% by mass or more, more preferably 95% by mass or more, and still more preferably 97% by mass or more based on the total amount of the cellulose derivative composition. The water content is preferably 99.98% by mass or less, more preferably 99.95% by mass or less, and 99.9% by mass or less based on the total amount of the cellulose derivative composition. More preferably it is.

<Method for producing cellulose derivative composition>
According to one embodiment of the present invention, there is provided a method for producing a cellulose derivative composition containing cellulose derivative particles and water. At this time, the number of the cellulose derivative particles having a particle diameter of 10 μm or more is 25 or less per 1 cm ³ .

  The production method of the cellulose derivative composition having the above-described configuration is not particularly limited. For example, a step of adding a cellulose derivative particle to water to prepare a cellulose derivative solution and stirring the resulting solution (hereinafter simply referred to as “the cellulose derivative composition”). A method including a stirring step). By performing this step, an appropriate shearing force is applied to the cellulose derivative particles, and the cellulose derivative composition having the above-described configuration can be more efficiently produced. Hereinafter, the stirring step will be described in detail.

(Stirring process)
The cellulose derivative particle content in the cellulose derivative solution used in this step is preferably 0.1% by mass or more, and more preferably 1% by mass or more. It is preferable that the content of the cellulose derivative is 0.1% by mass or more because the cellulose derivative composition can be efficiently prepared.

  Moreover, it is preferable that it is 10 mass% or less, and, as for content of the cellulose derivative particle in the cellulose derivative solution used at this process, it is more preferable that it is 3 mass% or less. If the content of the cellulose derivative is 10% by mass or less, it is preferable because gelation can be prevented during the preparation of the cellulose derivative composition.

  In addition, examples of the stirring container used in this step include a vertical stirring container and a horizontal stirring container.

  The vertical stirring container is a container having a vertical rotation shaft and a stirring blade attached to the vertical rotation shaft. Examples of the type of the stirring blade include a propeller blade, a turbine blade, a paddle blade, a fiddler blade, an anchor blade, a full zone (registered trademark) blade (manufactured by Shinko Pantech Co., Ltd.), a sun meller blade (manufactured by Mitsubishi Heavy Industries, Ltd.), Max. Examples include Blend (registered trademark) wings (manufactured by Sumitomo Heavy Industries, Ltd.), helical ribbon wings, and twisted lattice wings (manufactured by Hitachi, Ltd.).

  The horizontal stirring vessel is a horizontal type (horizontal direction) of a plurality of stirring blades provided inside, and has a plurality of stirring blades extending substantially perpendicular to the rotation shaft, The stirring blades provided on the respective horizontal rotating shafts are arranged so as not to collide with each other by shifting the positions in the horizontal direction. Examples of the type of the stirring blade include a uniaxial stirring blade such as a disk type and a paddle type, and a biaxial stirring blade such as a spectacle blade and a lattice blade (manufactured by Hitachi, Ltd.). In addition, for example, stirring blades such as a wheel shape, a saddle shape, a rod shape, and a window frame shape may be mentioned.

The size of the stirring vessel is not particularly limited, and for example, a vessel having a size of preferably 0.01 m ³ or more, more preferably 0.1 m ³ or more, and further preferably 1 m ³ can be used. The size of the stirring vessel is preferably 20 m ³ or less, more preferably 10 m ³ or less.

  The material of the stirring vessel is not particularly limited. For example, stainless steel is preferable, and the inner wall of the tank is more preferably coated with SUS316, glass, Teflon, titanium, or the like.

  A baffle can be installed in the stirring container as necessary. The size, shape, and number of baffle plates are not particularly limited.

  The strength and size of the rotating shaft are not particularly limited. The material of the rotating shaft is not limited. For example, it is preferably made of stainless steel, more preferably glass, Teflon, titanium coated, or SUS316 stainless steel.

  The number of stirring blades to be used is not particularly limited, and may be, for example, 1 to 10, preferably 1 to 5, and more preferably 2 to 5. When three or more stirring blades are used, the interval between the stirring blades at a plurality of locations is not limited, but it is preferable to arrange them uniformly.

  The size of the stirring blade is not limited, for example, the ratio (L / D) of the stirring blade diameter (L) to the inner diameter (D) of the stirring vessel is preferably 0.1 or more, more preferably 0.25 or more. Can do. Further, L / D is preferably 0.9 or less, more preferably 0.75 or less. The “inner diameter of the stirring vessel” refers to the longest diameter in the direction perpendicular to the rotation axis inside the stirring vessel. For example, when using a stirring container composed of a cylindrical part sandwiched between upper and lower mirror parts of the stirring container (round parts of the upper and lower parts of the stirring container), it refers to the diameter of the cylindrical part in the tank. The “stirring blade diameter” refers to a diameter obtained by doubling the longest distance from the center of the rotating shaft to the tip of the stirring blade. The “stirring blade tip” refers to the farthest portion when measured perpendicularly from the rotation axis.

  In this step, adjacent stirring blades may form any angle when viewed in the axial direction. From the viewpoint of efficient stirring, 0 degree (parallel) or 90 degrees (right angle) is preferable.

  The material of the stirring blade is not particularly limited, and is preferably made of, for example, stainless steel, more preferably coated with glass, Teflon, titanium, or stainless steel of SUS316.

  The atmosphere in the stirring vessel at the time of stirring is not particularly limited, and examples thereof include an air atmosphere and an inert gas atmosphere such as argon and nitrogen, and the reaction can be performed under normal pressure or reduced pressure.

  The rotation speed of the stirring blade is preferably 100 rpm or more, more preferably 150 rpm or more, and further preferably 200 rpm or more. When the rotation speed of the stirring blade is 50 rpm or more, more efficient stirring is achieved, and the cellulose derivative composition having the above-described configuration can be stably produced.

  Further, the rotational speed of the stirring blade is preferably 500 rpm or less, more preferably 400 rpm or less, and further preferably 300 rpm or less. If the rotation speed of the stirring blade is 500 rpm or less, the rotational vortex due to stirring does not become too large, gas entrapment is reduced, and deterioration due to shearing of the cellulose derivative particles themselves can be suppressed.

  The temperature during stirring is preferably 20 ° C. or higher, and more preferably 30 ° C. or higher. Moreover, the temperature at the time of stirring is preferably 80 ° C. or less, and more preferably 60 ° C. or less. As a method for heating the stirring vessel, a heating medium jacket is installed on the outer periphery of the stirring vessel, and the solution is heated by heat transfer through the wall of the stirring vessel, or the heat is transferred through a heat transfer tube (coil) inside the stirring vessel. The method etc. which heat by these are mentioned, These may be used individually or may be used in combination.

  The stirring time is preferably 10 minutes or more, and more preferably 120 minutes or more. The stirring time is preferably 1500 minutes or less, and more preferably 500 minutes or less.

  Furthermore, you may provide the ultrasonic oscillator which applies an ultrasonic vibration to the solution in a stirring container in the outer side of a stirring container. By applying ultrasonic vibration to the cellulose derivative solution, the cellulose derivative composition having the above-described configuration can be more efficiently produced. This ultrasonic oscillator applies, for example, ultrasonic vibration of about 900 W at 950 kHz to the solution in the stirring vessel.

  In addition, the cellulose derivative particles contained in the cellulose derivative composition according to this embodiment may contain impurities derived from the production of cellulose derivative particles. Therefore, in the method for producing a cellulose derivative composition according to the present invention, in addition to the stirring step, a step of removing or reducing the impurities may be performed. Thereby, in the cellulose derivative composition of this invention, the impurity derived from manufacture of a cellulose derivative particle is reduced more, and the cellulose derivative composition which has the above structures can be manufactured more efficiently.

  The step of removing or reducing the impurities is not particularly limited as long as impurities derived from the production of the cellulose derivative can be removed or reduced, but (A) a step of dissolving and filtering the cellulose derivative, and (B) classifying the cellulose derivative. Or (C) a step of dissolving the cellulose derivative and removing cations contained in impurities derived from the production of the cellulose derivative.

  Hereinafter, (A) a step of dissolving and filtering the cellulose derivative, (B) a step of classifying the cellulose derivative, and (C) a step of removing cations contained in impurities derived from the production of the cellulose derivative will be described.

[Step (A): Step of dissolving and filtering the cellulose derivative]
In this step, the cellulose derivative is dissolved in a solvent to prepare a cellulose derivative solution, and then filtered. By this step, impurities derived from the production of the cellulose derivative, preferably at least a part of the silica aggregate can be removed.

  The solvent is not particularly limited as long as it can dissolve the cellulose derivative, but water can be preferably used. Furthermore, since the dispersion stability of a cellulose derivative increases, it is preferable to add a general basic compound to the above-mentioned solvent.

  The pH of the cellulose derivative solution is preferably more than 7, more preferably 8 or more, and further preferably 10 or more.

  The cellulose derivative content in the cellulose derivative solution used in this step is preferably 0.01% by mass or more, and more preferably 0.1% by mass or more. When the content of the cellulose derivative is 0.01% by mass or more, a certain amount or more of the cellulose derivative solution can be filtered, which is preferable from the viewpoint of productivity.

  In addition, the content of the cellulose derivative in the cellulose derivative solution is preferably 10% by mass or less, and more preferably 5% by mass or less. It is preferable that the content of the cellulose derivative is 10% by mass or less because the viscosity of the cellulose derivative solution is not excessively high and a high filtration rate is obtained.

  Although it does not restrict | limit especially as a filter medium used for filtration of a cellulose derivative solution, Polypropylene, polystyrene, polyether sulfone, nylon, a cellulose, a polytetrafluoroethylene (PTFE), a polycarbonate, glass etc. are mentioned.

  Although it does not restrict | limit especially as a filter structure, A depth structure, a pleat structure, a membrane structure etc. are mentioned.

  The opening of the filter is not particularly limited, but is preferably 0.05 μm or more, more preferably 0.1 μm or more, and further preferably 0.2 μm or more. A filter opening of 0.05 μm or more is preferable because a high filtration rate can be obtained.

  Further, the opening of the filter is preferably 100 μm or less, more preferably 70 μm or less, and further preferably 50 μm or less. It is preferable that the opening of the filter is 100 μm or less because the filtration accuracy is improved.

  The filtration method may be natural filtration performed at normal pressure, suction filtration, pressure filtration, or centrifugal filtration.

  This step may be performed twice or more. At this time, it is preferable to appropriately change conditions such as the opening of the filter. For example, in the first dissolution filtration, coarse particles are removed using a wide-opening filter, and in the second dissolution filtration, fine particles are removed using a narrow-opening filter. By performing dissolution filtration twice or more, it becomes possible to remove impurities more efficiently.

[Step (B): Step of classifying cellulose derivative]
This step is a step of classifying the cellulose derivative. By this step, impurities derived from the production of the cellulose derivative, preferably hardly soluble inorganic salt, silica aggregate, unreacted cellulose, more preferably hardly soluble inorganic salt, and at least part of the aggregate can be removed. . In the present specification, “classification” means separation of impurities having a particle diameter of a certain size or more from cellulose derivatives containing impurities. The classification is usually performed using a classification device.

  Examples of classifiers include, for example, sieving devices such as vibrating screeners, low head screens, electromagnetic screens, dry classifiers such as micron separators, cyclone devices, etc., wet classifiers such as decanter centrifuges, liquid cyclone devices, and drug classifiers. These classification devices may be appropriately combined.

  This step may be performed twice or more. At this time, it is preferable to appropriately change the conditions such as the type of sieve and the classification method. For example, in the first classification, a cyclone classification is performed, and in the second classification, a resonance vibration sieve classification is performed. Moreover, you may crush a cellulose derivative between each classification. By performing the classification twice or more, impurities can be more efficiently removed.

[Step (C): Step of removing cations contained in impurities derived from production of cellulose derivative]
This step is a step of removing cations after dissolving the cellulose derivative in a solvent to prepare a cellulose derivative solution. By this step, impurities derived from the production of the cellulose derivative, preferably at least a part of the hardly soluble inorganic salt, can be removed.

  Since the kind of the solvent and the content of the cellulose derivative in the cellulose derivative solution are the same as those in the step of dissolving and filtering the cellulose derivative, description thereof is omitted here.

  The method for removing cations is not particularly limited, but it is preferable to use an ion exchange method. Examples of the ion exchange method include a method in which a cellulose derivative solution is passed through a column filled with an ion exchange resin to separate the cellulose derivative and impurities derived from the production of the cellulose derivative.

  Although it does not restrict | limit especially as an ion exchange resin which can be used, A strong acidic cation exchange resin, a weak acidic cation exchange resin, etc. are mentioned.

  Examples of the exchange group possessed by the strongly acidic cation exchange resin include a sulfonic acid group.

  Examples of the exchange group possessed by the weakly acidic cation exchange resin include a carboxy group and a phenolic hydroxyl group.

  Commercially available products may be used as the ion exchange resin. Examples of the commercially available products include Diaion (trademark) series (manufactured by Mitsubishi Chemical Corporation), Amberlite (trademark), Amberjet (trademark) (manufactured by Organo Corporation). ) And the like.

  This step may be performed twice or more. Under the present circumstances, it is preferable to change suitably conditions, such as pH of a cellulose derivative solution, and the kind of ion exchange resin. For example, in the first ion exchange, a cellulose derivative solution having a low pH (weakly basic) is used, and the pH of the cellulose derivative solution is adjusted before the second ion exchange to obtain a high pH (strongly basic) cellulose. For example, after the derivative solution is prepared, a second ion exchange method is performed. By performing ion exchange twice or more, it may be possible to remove impurities more efficiently.

  Moreover, it is preferable to remove anions together with removal of cations. More preferably, the anion is removed after the cation is removed. By removing the anion that binds to the residual cations that may be slightly present after the cation removal step, the possibility of producing a sparingly soluble inorganic substance can be reduced.

  Although it does not restrict | limit especially as an ion exchange resin which can be used for removal of an anion, A strong basic anion exchange resin I type, a strong basic anion exchange resin II type, a weak basic anion exchange resin, etc. are mentioned.

  Examples of the exchange group possessed by the strongly basic anion exchange resin type I include a trimethylammonium group.

  Examples of the exchange group possessed by the strongly basic anion exchange resin type II include a dimethylethanolammonium group.

  Examples of the exchange group possessed by the weakly basic anion exchange resin include a tertiary amino group.

  The above steps (A) to (C) may be performed alone or in combination of two or more. In this case, when two or more are combined, they may be performed in any order. That is, even if it carries out in order of a process (A) -process (B), it may carry out in the order of a process (A) -process (C), it is the order of a process (A) -process (B) -process (C). Even if it carries out, it may carry out in order of a process (A) -process (C) -process (B), and may be performed in order of a process (B) -process (A) -process (C). Among these, it is preferable to perform in order of a process (B) -process (A) -process (C).

  Further, as described above, each step may be performed twice or more. Therefore, step (A) -step (B) -step (A) -step (C), step (B) -step (B) -step (A) -step (C), step (B) -step (B ) -Step (A) -step (C) -step (C) and the like.

  In addition, when combining two or more of the above-described steps (A) to (C), naturally, known processes such as crushing, pH adjustment, and other purification processes are performed between the processes. Also good. Naturally, the above-described stirring step may be performed between the steps (A) to (C).

  Through the process of removing or reducing the impurities as described above, impurities derived from the production of the cellulose derivative can be further reduced.

<Polishing composition>
The cellulose derivative composition of the present invention can be used for various applications. For example, it can be used for applications such as polishing and rinsing after polishing. Of these, it is preferable to use for rinsing after polishing and polishing. Hereinafter, the use of the above-described composition for polishing will be described in detail.

  According to one form of this invention, the polishing composition containing the cellulose derivative composition of this invention is provided. According to the polishing composition according to this embodiment, the polished substrate (polishing object) can have excellent performance.

  Conventionally, a polishing composition containing a cellulose derivative, particularly an industrial cellulose derivative, may have different performance of the object to be polished depending on the lot of cellulose derivative used. As a result, each time a lot of cellulose derivatives is switched, an object to be polished having different performance is obtained, and this result can have a significant influence particularly in the semiconductor field requiring precision on the nano-order level.

  As a result of examining the change in the performance in detail, it has been found that minute defects (Light Point Defects, LPD) are generated on the surface of the object to be polished having a low performance. As a result of further detailed investigation, it was found that the number of LPDs differs depending on the lot of cellulose derivatives.

  The present inventors have found that the generation of LPD has a correlation with impurities that can be contained in the cellulose derivative, and have found that the generation of LPD can be prevented or suppressed by removing or reducing the impurities.

  The polishing composition according to this embodiment includes a cellulose derivative composition, silica particles, and a basic compound. Moreover, the other additive may be included as needed.

  The polishing composition preferably has a pH of 8 or more, more preferably 8.5 or more, and even more preferably 9 or more. It is preferable that the polishing composition has a pH of 8 or more because the function of chemically polishing the polished surface is improved and the dispersibility of silica particles and the like is improved.

  The pH of the polishing composition is preferably 12.5 or less, more preferably 12 or less, and even more preferably 11.5 or less. It is preferable that the polishing composition has a pH of 12.5 or less because the smoothness of the polished surface is improved. The pH of the polishing composition can be adjusted by the blending amount of a basic compound and a pH adjuster described later.

  Hereinafter, the components of the polishing composition will be described.

[Cellulose derivative composition]
Since what was mentioned above can be used as a cellulose derivative composition, description is abbreviate | omitted here. As described above, since the cellulose derivative composition of the present invention has no or almost no cellulose derivative particles having a large particle diameter, the polishing composition containing the cellulose derivative composition is used to polish an object to be polished. , It is possible to prevent or suppress the occurrence of LPD of the object to be polished, and to prevent or suppress the presence of foreign matter on the polishing surface.

  The content of the cellulose derivative particles in the polishing composition is preferably 0.002% by mass or more, more preferably 0.004% by mass or more, based on the total amount of the polishing composition. The amount is more preferably 0.006% by mass or more, and particularly preferably 0.01% by mass or more. It is preferable that the content of the hydrophilic component in the polishing composition is 0.002% by mass or more because the wettability of the polished surface is further improved.

  Further, the content of the cellulose derivative particles in the polishing composition is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, with respect to the total amount of the polishing composition. More preferably, it is 0.1% by mass or less. It is preferable that the content of the hydrophilic component in the polishing composition is 0.5% by mass or less because the dispersion stability of the polishing composition is improved.

[Silica particles]
The silica particles have a function of mechanically polishing the polishing surface.

  The silica particles are not particularly limited, and examples thereof include colloidal silica, fumed silica, and sol-gel silica. Among these, the silica particles are preferably colloidal silica or fumed silica, from the viewpoint of preventing or suppressing scratches that may occur on the polishing surface when a silicon substrate is used as the substrate, and may be colloidal silica. More preferred.

  The silica particles may be surface modified. By modifying the surface of the silica particles, since the zeta potential has a relatively large negative value, the dispersibility of the polishing composition can be improved, and the storage stability of the polishing composition can be improved.

  The surface-modified silica particles are preferably silica particles surface-modified with an organic acid (preferably colloidal silica). In this case, the organic acid is not particularly limited, and examples thereof include sulfonic acid, carboxylic acid, and phosphoric acid.

  The method for modifying the surface of the silica is not particularly limited, and known methods can be appropriately applied. For example, when surface-modifying sulfonic acid to colloidal silica, it can be performed by the method described in “Sulfonic acid-functionalized silica through quantitative oxidation of thiol groups” (Chem. Commun. 246-247 (2003)). Specifically, a silane coupling agent having a thiol group such as 3-mercaptopropyltrimethoxysilane is coupled to colloidal silica, and then the sulfonic acid is surface-modified by oxidizing the thiol group with hydrogen peroxide. Colloidal silica can be obtained. In addition, when surface-modifying carboxylic acid to colloidal silica, “Novel Silane Coupling Agents Containing a Photolabile 2-Nitrobenzyl Ester for Introduction of a Carboxy Group on the Surface of Silica Gel” (Chemistry Letters, 3, 228-229 ( 2000)). Specifically, a silane coupling agent containing a photoreactive 2-nitrobenzyl ester is coupled to colloidal silica, and then light irradiation is performed to obtain colloidal silica whose surface is modified with a carboxylic acid. it can.

  These silica particles may be used alone or in combination of two or more.

  The average primary particle diameter of the silica particles is preferably 5 nm or more, more preferably 10 nm or more, and further preferably 20 nm or more. It is preferable that the average primary particle diameter of the silica particles is 5 nm or more because the polishing rate of the silicon substrate is improved.

  The average primary particle size of the silica particles is preferably 100 nm or less, more preferably 70 nm or less, and further preferably 50 nm or less. It is preferable that the average primary particle diameter of the silica particles is 100 nm or less because the dispersion stability of the polishing composition is improved. In the present specification, the value of “average primary particle diameter of silica particles” is a value obtained by employing a specific surface area measured by the BET method using Flow SorbII 2300 (manufactured by Micromeritics). To do.

  The average secondary particle diameter of the silica particles is preferably 10 nm or more, more preferably 20 nm or more, and further preferably 30 nm or more. When the average secondary particle diameter of the silica particles is 10 nm or more, a high polishing rate can be obtained when polishing.

  Further, the average secondary particle diameter of the silica particles is preferably 200 nm or less, more preferably 150 nm or less, and further preferably 100 nm or less. It is preferable that the average primary particle diameter of the silica particles is 200 nm or less because the dispersion stability of the polishing composition is improved. In this specification, the value of “average secondary particle diameter of silica particles” is a value measured by a dynamic light scattering method using FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.). To do.

  The average value of the aspect ratio (major axis / minor axis ratio) of the silica particles is preferably 1.0 or more, more preferably 1.05 or more, and further preferably 1.1 or more. It is preferable that the average value of the aspect ratio of the silica particles is 1.0 or more because a high polishing rate can be obtained when polishing.

  The average value of the aspect ratio (major axis / minor axis ratio) of the silica particles is preferably 3.0 or less, more preferably 2.0 or less, and even more preferably 1.5 or less. . It is preferable that the average value of the aspect ratio of the silica particles is 3.0 or less because scratches that can occur on the polished surface can be prevented or reduced. In the present specification, “average value of aspect ratio (major axis / minor axis ratio)” is a value calculated by the following method. That is, 200 particles are observed using a scanning electron microscope (SEM), and a minimum rectangle circumscribing each particle image is drawn. And it can obtain | require by measuring the length (value of a major axis) of the long side with respect to the length (minor axis value) of the short side of the obtained rectangle, and calculating the average value.

  The true specific gravity of the silica particles is not particularly limited, but is preferably 1.5 or more, more preferably 1.6 or more, and still more preferably 1.7 or more. Further, the true specific gravity of the silica particles is preferably 2.2 or less, and more preferably 2.1 or less. When the true specific gravity of the silica particles is 1.5 or more, a high polishing rate can be obtained when polishing. In the present specification, as the value of “true specific gravity”, a value calculated from the mass when particles are dried and the mass when ethanol with a known capacity is filled therein is adopted.

  The content of the silica particles in the polishing composition is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, based on the total amount of the polishing composition. More preferably, it is 3 mass% or more. When the content of the silica particles in the polishing composition is 0.1% by mass or more, surface processing performance such as polishing rate with respect to the polishing surface is preferably improved.

  The content of the silica particles in the polishing composition is preferably 10% by mass or less, more preferably 5% by mass or less, and more preferably 3% by mass or less with respect to the total amount of the polishing composition. More preferably. It is preferable that the content of the silica particles in the polishing composition is 10% by mass or less because the dispersion stability of the polishing composition is improved and the residue of the silica particles on the polished surface is reduced.

[Basic compounds]
The basic compound has a function of chemically polishing the polished surface. It also has a function of improving the polishing rate. Furthermore, it has a function of improving the dispersion stability of the polishing composition.

  The basic compound is not particularly limited, and examples thereof include ammonia, amines, quaternary ammonium hydroxides or salts, alkali metal hydroxides or salts, and the like. At this time, examples of the salt include carbonates, bicarbonates, sulfates, acetates, and the like.

  Specific examples of amines include methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, ethylenediamine, monoethanolamine, N- (β-aminoethyl) ethanolamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, anhydrous piperazine , Piperazine hexahydrate, 1- (2-aminoethyl) piperazine, N-methylpiperazine, guanidine and the like.

  Examples of the quaternary ammonium hydroxide or salt include tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, ammonium hydrogencarbonate, and ammonium carbonate.

  Alkali metal hydroxides or salts include potassium hydroxide, potassium carbonate, potassium bicarbonate, potassium sulfate, potassium acetate, potassium chloride, sodium hydroxide, sodium carbonate, sodium bicarbonate, sodium sulfate, sodium acetate, sodium chloride Etc.

  Among the above basic compounds, ammonia, a hydroxide or salt of quaternary ammonium, an alkali metal hydroxide or salt, preferably ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide, ammonium hydrogencarbonate More preferably, ammonium carbonate, potassium hydroxide, potassium carbonate, potassium bicarbonate, sodium hydroxide, sodium carbonate, sodium bicarbonate, ammonia, tetramethylammonium hydroxide, tetraethylammonium hydroxide potassium hydroxide, hydroxide Sodium is more preferable, ammonia and tetramethylammonium hydroxide are particularly preferable, and ammonia is most preferable.

  Said basic compound may be used independently or may be used in combination of 2 or more type.

  The content of the basic compound in the polishing composition is preferably 0.001% by mass or more, more preferably 0.002% by mass or more, based on the total amount of the polishing composition. The content is more preferably 0.003% by mass or more, and particularly preferably 0.004% by mass or more. When the content of the basic compound in the polishing composition is 0.001% by mass or more, the chemical polishing action on the polishing surface is improved, and the dispersion stability of the polishing composition is improved. preferable.

  The content of the basic compound in the polishing composition is preferably 1.0% by mass or less, more preferably 0.5% by mass or less, with respect to the total amount of the polishing composition. The content is more preferably 0.2% by mass or less, and particularly preferably 0.1% by mass or less. It is preferable that the content of the basic compound in the polishing composition is 1.0% by mass or less because the smoothness of the polished surface is improved.

[Other additives]
Although it does not restrict | limit especially as an additive which can be contained in polishing composition, Abrasive grain, pH adjuster, surfactant, organic acid or its salt, inorganic acid or its salt, chelating agent, preservative, antifungal agent Etc.

(Abrasive grains)
The abrasive grains have a function of mechanically polishing the polishing surface together with the silica particles.

  Examples of the abrasive grains include inorganic particles other than silica particles, organic particles, and organic-inorganic composite particles.

Examples of inorganic particles other than the silica particles include alumina (Al ₂ O ₃ ) particles, ceria (CeO ₂ ) particles, titania (TiO ₂ ) particles, silicon nitride particles, silicon carbide particles, and boron nitride particles.

  Examples of the organic particles include polymethyl methacrylate (PMMA) particles.

  The content of the abrasive grains is not particularly limited and can be appropriately set according to the use of the polishing composition.

(PH adjuster)
The pH adjuster has a function of adjusting the pH of the polishing composition. By adjusting the pH, the polishing rate, the dispersibility of the silica particles, and the like can be controlled.

  It does not restrict | limit especially as a pH adjuster, A well-known acid, a base, or these salts are mentioned.

  Examples of the acid include inorganic acids such as hydrochloric acid, sulfuric acid, nitric acid, hydrofluoric acid, boric acid, carbonic acid, hypophosphorous acid, phosphorous acid, and phosphoric acid; formic acid, acetic acid, propionic acid, butyric acid, valeric acid, 2- Methylbutyric acid, n-hexanoic acid, 3,3-dimethylbutyric acid, 2-ethylbutyric acid, 4-methylpentanoic acid, n-heptanoic acid, 2-methylhexanoic acid, n-octanoic acid, 2-ethylhexanoic acid, benzoic acid , Glycolic acid, salicylic acid, glyceric acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, maleic acid, phthalic acid, malic acid, tartaric acid, citric acid, lactic acid, diglycolic acid, 2-furan Organic acids such as carboxylic acid, 2,5-furandicarboxylic acid, 3-furancarboxylic acid, 2-tetrahydrofurancarboxylic acid, methoxyacetic acid, methoxyphenylacetic acid, phenoxyacetic acid It is below. Of these, the pH adjuster is preferably sulfuric acid, nitric acid, phosphoric acid, glycolic acid, succinic acid, maleic acid, citric acid, tartaric acid, malic acid, gluconic acid, itaconic acid.

  Examples of the base include amines such as aliphatic amines and aromatic amines; organic bases; alkaline earth metal hydroxides and the like in addition to the basic compounds described above. Of these, the base is preferably potassium hydroxide or ammonia from the viewpoint of availability.

  Further, instead of or in combination with the above acid or base, a salt such as ammonium salt or alkali metal salt of the above acid may be used as a pH adjuster. In particular, when a combination of a weak acid and a strong base, a strong acid and a weak base, or a weak acid and a weak base is used, a pH buffering action can be obtained.

  The addition amount of the pH adjusting agent is not particularly limited, and can be appropriately set so that the polishing composition has a desired pH.

(Surfactant)
The surfactant has a function of suppressing the roughness of the polished surface. By suppressing the roughness of the polished surface, the haze of the polished surface can be reduced. In addition, since the polishing composition which concerns on this form contains the basic compound which performs chemical grinding | polishing, the roughness of a grinding | polishing surface can be suppressed more effectively by adding surfactant.

  The surfactant is not particularly limited, and examples thereof include nonionic or ionic surfactants having a weight average molecular weight of less than 1000.

  Examples of the nonionic surfactant include oxyalkylene polymers and polyoxyalkylene adducts.

  Examples of the oxyalkylene polymer include polyethylene glycol and polypropylene glycol.

  Examples of the polyoxyalkylene adduct include polyoxyethylene propyl ether, polyoxyethylene butyl ether, polyoxyethylene pentyl ether, polyoxyethylene hexyl ether, polyoxyethylene octyl ether, polyoxyethylene-2-ethylhexyl ether, polyoxyethylene Nonyl ether, polyoxyethylene decyl ether, polyoxyethylene isodecyl ether, polyoxyethylene tridecyl ether, polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene isostearyl ether, polyoxy Polyoxyethylene alkyl ethers such as ethylene oleyl ether; polyoxyethylene phenyl ether , Polyoxyethylene octyl phenyl ether, polyoxyethylene nonyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkylphenyl ether such as polyoxyethylene styrenated phenyl ether; polyoxyethylene laurylamine, polyoxyethylene stearylamine, Polyoxyethylene alkylamines such as polyoxyethylene oleylamine; polyoxyethylene alkylamides such as polyoxyethylene stearylamide, polyoxyethylene oleylamide; polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene distearate Acid ester, polyoxyethylene monooleate, polyoxyethylenediolate Polyoxyethylene fatty acid esters such as acid esters; polyoxyethylene glyceryl ether fatty acid esters; polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopaltimate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan monooleate, Polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan trioleate and polyoxyethylene sorbite tetraoleate; castor oil such as polyoxyethylene castor oil and polyoxyethylene hydrogenated castor oil; polyoxyethylene polyoxypropylene copolymer Examples thereof include copolymers such as coalescence.

  Among the above surfactants, the non-foaming surfactant is used from the viewpoint that handling at the time of preparation and use of the polishing composition is facilitated and pH adjustment is facilitated because of its low foamability. Is preferred.

  Said surfactant may be used independently or may be used in combination of 2 or more type.

(Organic acid or its salt / Inorganic acid or its salt)
The organic acid or salt / inorganic acid or salt thereof has a function of improving the hydrophilicity of the polished surface.

  The organic acid is not particularly limited, but fatty acids such as formic acid, acetic acid and propionic acid; aromatic carboxylic acids such as benzoic acid and phthalic acid; citric acid, oxalic acid, tartaric acid, malic acid, maleic acid, fumaric acid, succinic acid Examples thereof include polyvalent carboxylic acids such as acids; organic sulfonic acids; organic phosphonic acids and the like.

  Although it does not restrict | limit especially as an organic acid salt, Alkali metal salts, such as a sodium salt of the said organic acid, potassium salt, ammonium salt etc. are mentioned.

  Although it does not restrict | limit especially as an inorganic acid, A sulfuric acid, nitric acid, hydrochloric acid, carbonic acid, etc. are mentioned.

  Although it does not restrict | limit especially as an inorganic acid salt, Alkali metal salts, such as a sodium salt of the said inorganic acid and potassium salt; Ammonium salt etc. are mentioned.

  Among these, from the viewpoint of suppressing metal contamination of the abrasive product, it is preferable to use an ammonium salt of an organic acid or an inorganic acid.

  The above-mentioned organic acid or salt / inorganic acid or salt thereof may be used alone or in combination of two or more.

(Chelating agent)
The chelating agent is captured by forming a complex with a metal impurity, and has a function of preventing or suppressing metal contamination of the abrasive product.

  The chelating agent is not particularly limited, and examples thereof include aminocarboxylic acid chelating agents and organic phosphonic acid chelating agents.

  Examples of the aminocarboxylic acid chelating agent include ethylenediaminetetraacetic acid, ethylenediaminetetraacetic acid sodium, nitrilotriacetic acid, nitrilotriacetic acid sodium, nitrilotriacetic acid ammonium, hydroxyethylethylenediaminetriacetic acid, hydroxyethylethylenediaminetriacetic acid sodium salt, diethylenetriaminepentaacetic acid, Examples include sodium diethylenetriaminepentaacetate, triethylenetetraminehexaacetic acid, sodium triethylenetetraminehexaacetate, and the like.

  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). ), Triethylenetetraamine hexa (methylenephosphonic acid), ethane-1,1, -diphosphonic acid, ethane-1,1,2-triphosphonic acid, ethane-1-hydroxy-1,1-diphosphonic acid, ethane-1 -Hydroxy-1,1,2-triphosphonic acid, ethane-1,2-dicarboxy-1,2-diphosphonic acid, methanehydroxyphosphonic acid, 2-phosphonobutane-1,2-dicarboxylic acid, 1-phosphonobutane-2, 3,4-tricarboxylic acid, α-methylphosphonosuccinic acid And the like.

  Of the chelating agents, organic phosphonic acid chelating agents are preferable, and ethylenediaminetetrakis (methylenephosphonic acid) is more preferable.

  The above chelating agents may be used alone or in combination of two or more.

(Preservatives and fungicides)
The antiseptic / antifungal agent is not particularly limited, but isothiazoline compounds such as 2-methyl-4-isothiazolin-3-one and 5-chloro-2-methyl-4-isothiazolin-3-one; paraoxybenzoic acid Esters; phenoxyethanol and the like.

  The above-mentioned preservatives and fungicides may be used alone or in combination of two or more.

<Method for producing polishing composition>
It does not restrict | limit especially as a manufacturing method of polishing composition, A well-known method may be applied. As a specific example, it can manufacture by adding a silica particle, a basic compound, and arbitrary additives to a cellulose derivative composition one by one. Moreover, you may manufacture a polishing composition by adding a silica particle and a basic compound to a solvent, and mixing a cellulose derivative composition with the obtained liquid mixture. Of these, the polishing composition is preferably produced by the latter method. That is, in a preferred embodiment, a method for producing a polishing composition includes a step of preparing a mixed solution by adding silica particles and a basic compound to a solvent, and a step of adding a cellulose derivative composition to the mixed solution. including. At this time, the optional additive may be added to the mixed solution or the cellulose derivative composition.

  Hereinafter, the manufacturing method according to the preferred embodiment will be described.

[Step of adding silica particles and basic compound to solvent to prepare mixed solution]
In this step, a mixed solution is prepared.

  The mixed solution contains silica particles and a basic compound. Arbitrary additives may be included as necessary.

  The content of the silica particles in the mixed solution is preferably 1% by mass or more, more preferably 3% by mass or more, and further preferably 5% by mass or more with respect to the total amount of the mixed solution. It is preferable that the content of the silica particles is 1% by mass or more because the adjustment of the content of the silica particles in the polishing composition to be produced is easy.

  The content of silica particles in the mixed solution is preferably 50% by mass or less, more preferably 40% by mass or less, and further preferably 30% by mass or less, based on the total amount of the mixed solution. preferable. It is preferable that the content of the silica particles is 50% by mass or less because aggregation of the silica particles can be prevented.

  The content of the basic compound in the mixed solution is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, and more preferably 0.1% by mass or more with respect to the total amount of the mixed solution. More preferably. It is preferable that the content of the basic compound is 0.01% by mass or more because aggregation of silica particles can be suppressed.

  In addition, the content of the basic compound in the mixed solution is preferably 10% by mass or less, more preferably 5% by mass or less, and more preferably 3% by mass or less with respect to the total amount of the mixed solution. Further preferred. It is preferable for the content of the basic compound to be 10% by mass or less because the adjustment of the content of the basic compound in the polishing composition to be produced is easy.

  The pH of the mixed solution is preferably more than 7 (alkaline), more preferably 8 or more, and further preferably 9 or more. When the pH is more than 7, aggregation of silica particles is suppressed when the cellulose derivative composition is added to a mixed solution containing silica particles and the like. Thereby, the action of improving the dispersion stability of the finally obtained polishing composition tends to increase, which is preferable.

  Further, the pH of the mixed solution is preferably 12 or less, and more preferably 10.5 or less. A pH of 12 or less is preferable because dissolution of silica particles can be suppressed.

  The content of any additive can be appropriately set according to desired performance and the like.

[Step of adding cellulose derivative composition to mixed solution]
In this step, the cellulose derivative composition is added to the mixed solution prepared in the above step. Under the present circumstances, the said cellulose derivative composition may contain arbitrary additives as needed.

  When the pH of the mixed liquid is more than 7, since silica particles in the mixed liquid have high dispersion stability, it is possible to prevent or suppress silica aggregation that may occur when the cellulose derivative composition is added, preferable.

  The rate at which the cellulose derivative composition is charged into the mixed solution is preferably 0.1 mL / min or more, more preferably 1 mL / min or more, and more preferably 5 mL / min with respect to 1 L of the mixed solution. More preferably, it is the above. It is preferable that the input rate be 0.1 ml / L or more because the production efficiency of the polishing composition can be increased.

  Moreover, the rate at which the cellulose derivative composition is charged into the mixed solution is preferably 500 mL / min or less, more preferably 100 mL / min or less, and further preferably 50 mL / min or less with respect to 1 L of the mixed solution. A charging rate of 500 mL / min or less is preferable because silica aggregation can be suppressed.

  The polishing composition may be prepared by diluting a stock solution of the polishing composition with water. In this case, the dilution factor is preferably 2 times or more, more preferably 5 times or more, and more preferably 10 times or more. It is preferable that the dilution ratio is 2 times or more because the cost of transporting the stock solution of the polishing composition is reduced and the storage location can be saved.

  The dilution ratio is preferably 100 times or less, more preferably 50 times or less, and further preferably 40 times or less. It is preferable that the dilution ratio is 100 times or less because the stability of the stock solution of the polishing composition is easily maintained.

<Substrate manufacturing method>
The above-mentioned polishing composition can be used for polishing a substrate. Examples of the substrate include a substrate on which an inorganic insulating film such as a silicon oxide film and a silicon nitride film is formed, a substrate on which a polycrystalline silicon film is formed, a silicon wafer, and the like. Among these, since the polishing composition according to the present embodiment contains silica particles, it is preferable to apply a substrate on which a polycrystalline silicon film is formed, a silicon wafer, and a silicon wafer. More preferred. Thereby, a silicon wafer having high performance can be manufactured.

  That is, according to one form of this invention, the manufacturing method of a board | substrate is provided. The method for manufacturing the substrate includes polishing the substrate with a polishing composition.

  In many cases, a silicon wafer is manufactured by forming a silicon single crystal ingot by a Cz method (Czochralski method) or an Fz method (Floating Zone method), and processing this. At this time, the polishing composition described above includes a rough polishing step (primary polishing / secondary polishing) for planarizing the surface of a silicon substrate sliced into a disk shape from a silicon single crystal ingot, and a silicon substrate after the rough polishing step. It can be used in a final polishing step in which fine irregularities present on the surface are further removed to make a mirror surface. Since the polishing composition provides an object to be polished having excellent performance, it is preferably used in the final polishing step.

  The polishing apparatus that can be used is not particularly limited, and a holder for holding a substrate having a polishing object and a motor that can change the number of rotations are attached, and a polishing pad (polishing cloth) can be attached. A general polishing apparatus having a simple polishing surface plate can be used.

  The polishing pad is not particularly limited, and a general nonwoven fabric, polyurethane, porous fluororesin, or the like can be used. At this time, it is preferable that the polishing pad is grooved so that the polishing liquid is accumulated.

  The polishing conditions are not particularly limited and can be set as appropriate. For example, the rotational speed of the polishing platen is preferably 10 to 500 rpm. Moreover, it is preferable that the pressure (polishing pressure) applied to the substrate having the object to be polished is 0.5 to 10 psi.

  The method of supplying the polishing composition to the polishing pad is not particularly limited, and for example, a method of continuously supplying with a pump or the like is employed. At this time, the supply amount is not limited, but it is preferable that the surface of the polishing pad is always covered with the polishing composition of the present invention.

  When polishing the substrate using the polishing composition, the polishing composition once used for polishing may be collected and used again for polishing the substrate. As a method of reusing the polishing composition, for example, a method of collecting the polishing composition discharged from the polishing apparatus in a tank and circulating it again into the polishing apparatus can be used. The method for reusing the polishing composition is that the environmental load can be reduced by reducing the amount of the polishing composition discharged as waste liquid, and the polishing of the substrate can be performed by reducing the amount of the polishing composition to be used. This is useful in that the manufacturing cost can be suppressed.

  When the polishing composition is reused, it is preferable to add a part or all of each component such as a hydrophilic component consumed or lost by polishing as a composition modifier. In addition, the description which concerns on the manufacturing method of the above-mentioned polishing composition can be referred suitably for the preparation method of a hydrophilic component.

  The polishing composition may be applied to a polishing composition for obtaining a polishing product other than a silicon wafer. Specific examples of polishing products other than silicon wafers include metals such as stainless steel, plastic substrates, glass substrates, and quartz substrates. In addition, the component contained in polishing composition may be suitably changed according to polishing product.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" is used in an Example, unless otherwise indicated, "mass part" is represented.

(Example)
44.28 kg of hydroxyethyl cellulose (manufactured by Daicel Finechem) having a weight average molecular weight of 250,000 in terms of polyethylene oxide was added to 2700 kg of water and dissolved. The obtained solution was put into a bowl-shaped stirring vessel having a volume of 3 m ³ (L / D of stirring blade: 0.3) and stirred for 180 minutes at 25 ° C. in an air atmosphere at a rotation speed of the stirring blade of 250 rpm. A cellulose derivative composition was obtained.

(Comparative example)
Stirring was carried out in the same manner as in Example except that the stirring condition was set at 80 rpm, and a cellulose derivative composition was obtained.

  About the cellulose derivative composition obtained by the Example and the comparative example, the particle diameter and number of cellulose derivative particles were measured with the measuring apparatus and measurement conditions of the following Table 1.

  Moreover, the polishing composition was prepared with the following method using the cellulose derivative composition of the said Example and comparative example.

  As abrasive grains, high-purity colloidal silica (pH about 7.0) having an average primary particle diameter of 35 nm was diluted with ion-exchanged water to prepare 5000 g of a colloidal silica dispersion having a concentration of 20% by mass. The pH of the colloidal silica dispersion at this time was about 7.0. Next, 70 g of 29% ammonia water was added as a basic compound to adjust the pH to around 10.3 to prepare a colloidal silica dispersion.

  Next, 2000 g of an aqueous solution in which the concentration of hydroxyethyl cellulose was adjusted to 2% by mass using the cellulose derivative compositions of the above Examples and Comparative Examples was added to the colloidal silica dispersion having a pH of around 10.3. Finally, 3000 g of ultrapure water was added to prepare a polishing composition. Hereinafter, the polishing composition prepared by using the cellulose derivative composition of the example by the above method is referred to as a polishing composition 1. Moreover, the polishing composition prepared by using the cellulose derivative composition of the comparative example by the above method is referred to as a polishing composition 2.

  In the polishing composition 1 and the polishing composition 2, the content of each component with respect to the entire polishing composition is 0.5% by weight of abrasive grains, 0.01% by weight of ammonia, 0.01% by weight of hydroxyethyl cellulose, and Remaining water. In addition, the prepared polishing composition 1 and the polishing composition 2 were visually observed to confirm that there were no gelled components.

(Reference Example 1)
2000 g of an aqueous solution prepared by adjusting the cellulose derivative compositions of the above Examples and Comparative Examples to 2% by mass was prepared. Next, 70 g of 29% aqueous ammonia was added to adjust the pH to 10.6 to prepare an aqueous hydroxyethyl cellulose solution. Next, 2070 g of the hydroxyethyl cellulose solution was added to 5000 g of colloidal silica dispersion having a pH of 7.0 (adjusted to a concentration of 20% by mass). Finally, 3000 g of ultrapure water was added to prepare a polishing composition. In this method, even when using either the cellulose derivative composition of the example or the cellulose derivative composition of the comparative example, when the hydroxyethyl cellulose solution and the colloidal silica dispersion were mixed, a visually gelatinized component was observed. It was done.

(Reference Example 2)
To 5000 g of colloidal silica dispersion having a pH of 7.0 (adjusted to a concentration of 20% by mass), 2000 g of an aqueous solution prepared by adjusting the cellulose derivative compositions of the above Examples and Comparative Examples to 2% by mass was added. Next, 70 g of 29% aqueous ammonia was added. Finally, 3000 g of ultrapure water was added to prepare a polishing composition. In this method, both of the cellulose derivative composition of the example and the cellulose derivative composition of the comparative example were used, and when the colloidal silica dispersion and the hydroxyethyl cellulose aqueous solution were mixed, very much gelation was observed. Ingredients were observed.

  The silicon substrate was polished using the polishing composition 1 and the polishing composition 2 obtained above. The details of the silicon substrate used and the polishing conditions are shown in Table 2 below.

  LPD was measured for the polished silicon substrate. LPD is an abbreviation for Light Point Defect, which is a kind of substrate surface defect, and is generally caused by aggregates, insolubles, etc. in the polishing composition. As an LPD measuring device, Surfscan (registered trademark) SP2 (manufactured by KLA Tencor, USA) was used, and the measurement condition was an oblique mode (measuring defects of 37 nm or more).

  Table 3 below shows the particle size and number of cellulose derivative particles and the LPD measurement results.

  As is apparent from Table 3 above, it was found that the cellulose derivative compositions of the examples had almost no cellulose derivative particles having a large particle size. Furthermore, it was found that when the silicon substrate was polished with the polishing composition using the cellulose derivative composition of the example, LPD was reduced as compared with the polishing composition of the comparative example.

Claims (6)

Containing cellulose derivative particles and water,
The number of particle size 10μm or more of the cellulose derivative particles is less than or equal to 2 0 per 1 cm ^3, a method for producing a cellulose derivative composition,
The cellulose derivative particles are added to water to prepare a cellulose derivative solution, and the obtained solution is stirred using a stirring vessel equipped with a stirring blade,
The method for producing a cellulose derivative composition, wherein, in the stirring step, the rotation speed of the stirring blade is 100 rpm or more . The method for producing a cellulose derivative composition according to claim 1, wherein in the stirring step, the rotation speed of the stirring blade is 150 rpm or more . The method for producing a cellulose derivative composition according to claim 1 or 2 , wherein the number of the cellulose derivative particles having a particle diameter of 10 µm or more and less than 15 µm is 5 or less per 1 cm ³ . The method for producing a cellulose derivative composition according to any one of claims 1 to 3 , wherein the number of the cellulose derivative particles having a particle diameter of 15 µm or more is 8 or less per 1 cm ³ . Mixing the silica particles, the basic compound, and water;
To obtain a cellulose derivative composition by the method according to any one of claims 1 to 4, the cellulose derivative composition, relative to the mixture obtained in the step of the mixing, the steps of added pressure,
Method for producing a containing, Migaku Ken composition. 請 Motomeko 5 obtains by Ri Migaku Ken composition in the production method described in, comprising the step of polishing the substrate using the polishing composition, the manufacturing method of the substrate.