JP2020161531A - Polishing dispersion liquid, polishing sheet, and manufacturing method thereof - Google Patents

Abstract

To provide a polishing dispersion liquid capable of maintaining a state for a long time in which diamond particles are dispersed in a state of primary particles.SOLUTION: A method for manufacturing a polishing dispersion liquid includes steps of: obtaining a mixture of diamond particles having a primary median diameter of 0.1 to 5.0 μm and a polymer having a basic functional group having an amine value of 1.0 to 50 mg KOH/g in an organic solvent; and irradiating the mixture with ultrasound. The dispersion liquid is obtained by the same.SELECTED DRAWING: Figure 1

Description

The present invention relates to a dispersion liquid for polishing and a polishing sheet, and a method for producing these.

Conventionally, precision polishing using a polishing sheet has been performed on the surface of materials such as metals, semiconductors, and oxides thereof. For example, the surface of a silicon wafer used as a component of a semiconductor device is finished into a high-quality mirror surface through a wrapping process and a polishing process.

As an abrasive used for the polishing sheet, a tape using chromium oxide, aluminum oxide, silicon carbide or the like is known. Since the hardness of such an abrasive is as hard as the Mohs hardness of 8.5 to 9.5, it has been widely used for polishing sheets.

In polishing the surface of a silicon wafer, a polishing agent having a higher Mohs hardness than these polishing agents is required, and therefore, a polishing sheet using diamond particles has been used as the polishing agent. In recent years, with the improvement of high performance and high integration of semiconductor devices, improvement of quality of silicon wafers is required.

In Patent Document 1, as a method for producing a polishing tape, a polishing paint is obtained by diluting a mixture of a binder and diamond particles with an organic solvent and then stirring the mixture, and further polishing using ultrasonic waves. A method of decomposing secondary particles of diamond particles in a coating material into the form of primary particles and dispersing them in the polishing paint is disclosed.
However, with this method, the secondary particles cannot be sufficiently decomposed into primary particles, and even if they are once in the state of primary particles, they have poor storage stability and therefore reaggregate in a short period of time. There is. Therefore, since the polishing tape produced by the polishing paint contains secondary particles in which diamond particles are reaggregated, unevenness and scratches are generated on the surface to be polished, and sufficient polishing performance cannot be obtained. was there.

Therefore, there has been a demand for a polishing dispersion liquid capable of maintaining a state in which diamond particles are dispersed for a long period of time in the state of primary particles, and a polishing sheet having excellent polishing performance.

Japanese Unexamined Patent Publication No. 2006-142388

An object of the present invention is to provide a dispersion liquid for polishing capable of maintaining a state in which diamond particles are dispersed in the state of primary particles for a long period of time. Another object of the present invention is to provide a polishing sheet capable of polishing the surface to be polished of the object to be polished without causing unevenness or scratches.

The first invention comprises, in an organic solvent, diamond particles having a median diameter of 0.1 to 5.0 μm as primary particles, and a polymer having a basic functional group having an amine value of 1.0 to 50 mgKOH / g. This is a method for producing a dispersion liquid for polishing, which comprises a step of obtaining a mixed liquid by containing the mixture and a step of irradiating the mixed liquid with ultrasonic waves.

The second invention is the method for producing a dispersion for polishing according to the first invention, wherein the polymer having a basic functional group has an acid value of 1.0 to 50 mgKOH / g.

The third invention comprises an organic solvent, diamond particles having a median diameter of 0.1 to 5.0 μm as primary particles, and a polymer having a basic functional group having an amine value of 1.0 to 50 mgKOH / g. It is a dispersion liquid for polishing characterized by containing at least.

The fourth invention is the dispersion liquid for polishing according to the third invention, wherein the standard deviation of the median diameter of the diamond particles is 0.01 to 5.0.

The fifth invention is the polishing dispersion according to the third or fourth invention, wherein the polymer having a basic functional group has an acid value of 1.0 to 50 mgKOH / g.

A sixth invention is a polishing dispersion containing at least an organic solvent, diamond particles, and a polymer having a basic functional group having an amine value of 1.0 to 50 mgKOH / g. A step of mixing a resin and a polishing resin composition to obtain a polishing resin composition, and after applying the polishing resin composition on a flexible base material, the organic solvent in the polishing resin composition is removed to form a polishing layer. A method for producing a polishing sheet, which comprises a step of forming the polishing sheet.

The seventh invention is the method for producing a polishing sheet according to the sixth invention, wherein the median diameter of the primary particles of the diamond particles is 0.1 to 5.0 μm.

The eighth invention is the production of the polishing sheet according to any one of the sixth or seventh invention, wherein the polymer having a basic functional group has an acid value of 1.0 to 50 mgKOH / g. The method.

According to the ninth invention, in a polishing sheet having a polishing layer on a flexible base material, the polishing layer is diamond particles having a median diameter of 0.1 to 5.0 μm as primary particles and an amine value of 1.0. It is a polishing sheet characterized by containing at least a polymer having a basic functional group of about 50 mgKOH / g and a resin.

The tenth invention is the polishing sheet according to the ninth invention, wherein the polymer having a basic functional group has an acid value of 1.0 to 50 mgKOH / g.

The eleventh invention is the polishing sheet according to the ninth or tenth invention, wherein the arithmetic mean roughness of the surface of the polishing layer is 0.05 to 3.0 μm.

The polishing dispersion obtained by the method for producing a polishing dispersion of the present invention can maintain a state in which diamond particles are dispersed in the state of primary particles for a long period of time. further. By using the polishing dispersion, it is possible to manufacture a polishing sheet capable of polishing without causing unevenness or scratches on the polished surface of the object to be polished.

It is a figure which shows the SEM photograph which took the dispersion liquid of Example 1 of this invention by the cryo-SEM method at a magnification of 10,000 times. It is a figure which shows the SEM photograph which took the dispersion liquid of the comparative example 1 of this invention by the cryo-SEM method at a magnification of 10,000 times. It is a figure which shows the SEM photograph which took the surface of the polishing layer in the polishing sheet of Example 8 of this invention at a magnification of 30,000 times. It is a figure which shows the SEM photograph which took the surface of the polishing layer in the polishing sheet of the comparative example 7 of this invention at a magnification of 30,000 times.

First, the method for producing the polishing dispersion of the present invention will be described.

<Manufacturing method of dispersion for polishing>
In the method for producing a dispersion for polishing of the present invention, diamond particles having a median diameter of 0.1 μm to 5.0 μm of primary particles and a basic functional group having an amine value of 1.0 to 50 mgKOH / g are used in an organic solvent. A method for producing a dispersion liquid for polishing, which comprises a step of obtaining a mixed liquid by containing a polymer having the above, and a step of irradiating the mixed liquid with ultrasonic waves.

The polishing dispersion obtained by the method for producing a polishing dispersion of the present invention is a polishing dispersion capable of maintaining a state in which diamond particles are dispersed for a long period of time in the state of primary particles.

<Diamond particles>
The diamond particles used in the present invention may be single crystal diamond particles or polycrystalline diamond particles. As the diamond particles used in the present invention, it is preferable to use single crystal diamond particles from the viewpoint of improving the polishing rate.
The median diameter of the primary particles of the diamond particles used in the present invention is a single crystal or polycrystalline diamond particle in the range of 0.1 to 5.0 μm.

In the present invention, the median diameter of the primary particles of the diamond particles refers to the diameter (D50) which is the volume% in the distribution curve of the integrated% of the dispersed diamond particles detected by the laser diffraction / scattering type particle size distribution measuring device.

According to the production method of the present invention, the standard deviation of the primary particles of diamond particles is characterized by falling within a specific range.

Standard deviation of particle size (STD. DEV .; Standard Deviation)
) Is calculated by the following formula.
STD. DEV. = (D84% -d16%) / 2
In the above formula, d84% represents the particle diameter when the cumulative curve is 84% when the cumulative curve is calculated with the total volume of the powder population as 100%, and d16% is the cumulative curve of 16%. Represents the particle size when it becomes.

The standard deviation of the grain size of the diamond particles is 0.01 to 5.0, preferably 0.01 to 2.0, and particularly preferably 0.01 to 0.5. When the standard deviation of the particle size of the diamond particles falls within this range, a polishing sheet having excellent polishing performance can be manufactured.

In addition to diamond particles, the polishing dispersion may contain alumina particles and / or silica particles as an abrasive.

The content of diamond particles in the dispersion for polishing is preferably 20% by mass or more, more preferably 25% by mass or more, and particularly preferably 30% by mass or more. By using such a high-concentration polishing dispersion, it is possible to manufacture a polishing sheet having high density of diamond particles.

Specifically, the polishing dispersion containing 20% by mass of diamond particles has a feature that almost no agglomerates of diamond particles are observed even when left at a temperature of 40 ° C. for one week.

<Polymer with basic functional groups>
The amine value of the polymer having a basic functional group used in the present invention is preferably 1.0 mg to 50 mgKOH / g, and more preferably 5 mg to 40 mgKOH / g. By using a polymer having such a basic functional group, it is possible to obtain a polishing dispersion in which the diamond particles in the polishing dispersion are in the state of primary particles and can be dispersed for a long period of time.

Moreover, the polymer having the basic functional group may have an acidic functional group.

Examples of the polymer having a basic functional group include secondary, tertiary or quaternary amines as the basic functional group. Examples of the acidic functional group include carboxylic acid, sulfate and phosphate. A polymer has a molecular weight of more than 500, generally more than 1000. Examples of the polymer include hydrocarbons, polyacrylics, polymethacrylics, polyurethanes, polyesters, polyethers, polyimines, and copolymers thereof.

Specific examples of the polymer having a basic functional group, the polymer having a basic functional group and the acidic functional group include the (co) weight of "unsaturated carboxylic acid ester such as (meth) acrylic acid ester". Combined; (partial) amine salt, (partial) ammonium salt or alkylamine salt of "(co) polymer of unsaturated carboxylic acid such as (meth) acrylic acid"; "primary, secondary or tertiary amino group" (Co) polymer of "unsaturated carboxylic acid ester such as (meth) acrylic acid ester", salt of amino group of the (co) polymer, (partial) acid modification of the amino group of the (co) polymer (Co) polymers of "hydroxyl-containing unsaturated carboxylic acid esters such as hydroxyl group-containing (meth) acrylic acid esters" and their modified products; polyurethanes; unsaturated polyamides; polysiloxanes; long-chain polyaminoamide phosphorus Examples thereof include amides obtained by reacting poly (lower alkyleneimine) with a free carboxy group-containing polyester and salts thereof.

Among the above-mentioned polymers having a basic functional group, an amine salt of an acrylic polymer, an amine salt of a block copolymer, an amine salt of a polyester polymer, or an amine salt of a urethane polymer is preferably used.

In the production method of the present invention, it is particularly preferable to use a polymer having an acidic functional group and a basic functional group from the viewpoint that diamond particles can be dispersed for a long period of time.

The acid value of the polymer having a basic functional group and an acidic functional group is preferably 1.0 mgKOH / g to 50 mgKOH / g, and more preferably 2.0 mgKOH / g to 30 mgKOH / g.
Within such a range, a dispersion liquid for polishing having particularly excellent dispersion stability of diamond particles can be obtained.

The content of the polymer having a basic functional group in the polishing dispersion is 0.1 to 10% by mass, preferably 0.2 to 8.0% by mass, and 0.5 to 5.0% by mass. Particularly preferred. Within such a range, diamond particles can be dispersed in an organic solvent in the state of primary particles for a long period of time.

By containing a polymer having a basic functional group, it has an action of adsorbing to the surface of diamond particles and suppressing reaggregation. Therefore, the diamond particles in the dispersion liquid for polishing become secondary particles due to reaggregation and do not precipitate, and can maintain a dispersed state for a long period of time in the state of primary particles.

<Organic solvent>
The organic solvent used in the present invention has a role as a dispersion medium for the polishing dispersion.

Organic solvents include monovalent alcohols (methanol, ethanol, propanol, butanol, pentanol, hexanol, cyclobutanol, cyclopentanol, cyclohexanol, benzyl alcohol, etc.), polyhydric alcohols and oxyalcohol compounds (ethylene glycol). , Propyl glycol, glycerin, methyl cellosolve, ethyl cellosolve, methoxypropylene glycol, dimethoxypropanol, etc.), acetone, ketones such as methyl ethyl ketone, γ-butyrolactone, γ-valerolactone, amide type (N-methylformamide, N, N- Dimethylformamide, N-ethylformamide, N, N-diethylformamide, N-methylacetamide, N, N-dimethylacetamide, N-ethylacetamide, N, N-diethylacetamide, hexamethylphosphoricamide, etc.), Sulforane-based ( Sulfone, 3-methylsulfone, 2,4-dimethylsulfone, etc.), chain sulfone (dimethylsulfone, ethylmethylsulfone, ethylisopropylsulfone), cyclic amide (N-methyl-2-pyrrolidone, etc.), carbonates (carbonates, etc.) Ethylene carbonate, propylene carbonate, isobutylene carbonate, etc.), nitrile type (acetamide, etc.), sulfoxide type (dimethyl sulfoxide, etc.), 2-imidazolidinone type [1,3-dialkyl-2-imidazolidinone (1,3-dimethyl, etc.) -2-Imidazolidinone, 1,3-diethyl-2-imidazolidinone, 1,3-di (n-propyl) -2-imidazolidinone, etc.), 1,3,4-trialkyl-2-imidazo) Ridinone (1,3,4-trimethyl-2-imidazolidinone, etc.)] and the like.

The organic solvent may be used alone or in combination of two or more. For the purpose of improving the dispersibility of the diamond particles and the ease of mixing the resin to be used and the dispersion liquid for polishing, it is preferable to use two or more kinds in a mixed manner.

<Additives>
The polishing dispersion of the present invention may contain additives in addition to diamond particles and a polymer having a basic functional group. Additives include polyethylene glycol, polyvinyl alcohol, phosphoric acid compounds of dibutyl phosphate or phobic acid, complex compounds such as boric acid, mannit, boric acid and mannit, sorbit, and boric acid and ethylene glycol, glycerin and the like. Examples thereof include boron compounds such as complex compounds with hydrating alcohols, and nitro compounds such as o-nitrobenzoic acid, m-nitrobenzoic acid, p-nitrobenzoic acid, o-nitrophenol, m-nitrophenol and p-nitrophenol. ..

The content of the additive in the dispersion for polishing is preferably 0.1 to 5.0% by mass, more preferably 0.1 to 2.0% by mass. If it is less than 0.1% by mass, sufficient dispersion stability may not be obtained, and if it exceeds 5% by mass, it may aggregate.

<Step of irradiating the mixed solution with ultrasonic waves>
The production method of the present invention is characterized by including a step of irradiating the mixed solution with ultrasonic waves. By irradiating the mixed solution with ultrasonic waves, diamond particles having a median diameter of 0.1 μm to 5.0 μm of the primary particles of the diamond particles and a basic functional group having an amine value of 0.1 to 50 mgKOH / g By irradiating the mixed solution with ultrasonic waves containing a polymer having a diamond particle, not only the van der Waals force of the aggregate of diamond particles is released, but also the diamond particles are polished to form the shape of the diamond particles. Is closer to a sphere, and diamond particles of uniform size can be obtained.

Examples of the method of irradiating ultrasonic waves include a method of irradiating the mixed solution with ultrasonic waves using an ultrasonic oscillator, an ultrasonic bath for cleaning glassware, and the like.

The time for irradiating the mixed solution with ultrasonic waves is preferably 5 minutes to 10 hours, more preferably 10 minutes to 5 hours, and particularly preferably 15 minutes to 2 hours.
In less than 5 minutes, the van der Waals force of the agglomerates of diamond particles may not be sufficiently released, and in more than 10 hours, the diamond particles themselves may be polished and the desired particle size may not be obtained. There is sex.

As the polishing dispersion obtained by the production method of the present invention, the polishing dispersion itself may be used for polishing, or a polishing sheet may be prepared using the polishing dispersion.
As a method of using the polishing dispersion itself for polishing, for example, a polishing object is set in a general polishing device, and the polishing dispersion is supplied to the surface of the polishing object through the polishing pad of the polishing device. The polishing object can be polished by continuously supplying the polishing dispersion liquid and pressing the polishing pad against the surface of the object to be polished and rotating both of them relatively.

<Manufacturing method of polishing sheet>
The step of mixing the above-mentioned polishing dispersion and the resin to obtain a polishing resin composition, and after applying the polishing resin composition on a flexible substrate, the solvent in the polishing resin composition Is a method for producing a polishing sheet, which comprises a step of removing the above-mentioned material to form a polishing layer.

<Resin>
As the resin used in the present invention, a thermoplastic resin or a thermosetting resin can be used.

The thermoplastic resin can be arbitrarily selected from the thermoplastic resins usually used as molding materials. Such, but not particularly limited, polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, polycaprolactone, acrylonitrile-butadiene-styrene resin, polystyrene, methacrylic resin, polyamide, polycarbonate, polybutylene terephthalate, Examples thereof include polyphenylene sulfide, polyacetal, modified polyphenylene ether, polysulfone, liquid crystal polymer, acrylonitrile / styrene resin, and various thermoplastic elastomers.
Further, more preferably, a plant-derived thermoplastic resin is preferably mentioned from the viewpoint of reducing the amount of fossil resources used. Specifically, polylactic acid, esterified starch, polyhydroxyalkanoic acid, polytrimethylene terephthalate, polybutylene terephthalate, succinic acid, itaconic acid, 1,3-propanediol, 1,4-butanediol and the like are synthesized as monomers. The polyester resin or the like can be used, and one type may be used alone or two or more types may be used in combination.

The thermosetting resin can be arbitrarily selected from the thermosetting resins used as ordinary molding materials. Examples of such a resin include, but are not limited to, epoxy resin, phenol resin, furan resin, urea resin, melamine resin, unsaturated polyester resin, and silicon resin.

Examples of the epoxy resin include bisphenol A glycidyl ether type epoxy, bisphenol F glycidyl ether type epoxy, bisphenol S glycidyl ether type epoxy, bisphenol AD glycidyl ether type epoxy, phenol novolac type epoxy, biphenyl type epoxy, and cresol novolac type epoxy. Can be mentioned. Further, it is preferable that the epoxy resin is obtained from a naturally derived substance from the viewpoint of reducing the environmental load. Specific examples thereof include epoxidized soybean oil, epoxidized fatty acid esters, epoxidized linseed oil, and dimer acid-modified epoxy resin.

Examples of the phenolic resin include those obtained by reacting phenols such as phenol and cresol with formaldehyde and the like to synthesize a novolak type phenolic resin and the like, blending hexamethylenetetramine and the like with the compound, and curing the resin. For example, phenols such as phenol, cresol, resorcin, catechol, bisphenol A, bisphenol F, phenylphenol, aminophenol and / or naphthols such as α-naphthol, β-naphthol, dihydroxynaphthalene, formaldehyde, benzaldehyde, salicylaldehyde and the like. Phenolic aralkyl resin synthesized from dimethoxyparaxylene or bis (methoxymethyl) biphenyl with novolak-type phenolic resin, phenols and / or naphthols obtained by condensing or co-condensing with a compound having an aldehyde group of , Biphenylene-type phenol aralkyl resin, naphthol aralkyl resin and other aralkyl-type phenolic resins, phenols and / or naphthols and dicyclopentadiene synthesized by copolymerization, dicyclopentadiene-type phenol novolac resin, dicyclopentadiene-type naphthol novolac. Dicyclopentadiene-type phenolic resin such as resin, triphenylmethane-type phenolic resin, terpene-modified phenolic resin, paraxylylene and / or metaxylylene-modified phenolic resin, melamine-modified phenolic resin, cyclopentadien-modified phenolic resin, two or more of these are copolymerized. Examples thereof include the phenolic resin obtained. These may be used alone or in combination of two or more.

Examples of the furan resin include furfural resin, furfural phenol resin, furfural ketone resin, furfuryl alcohol resin, and furfuryl alcohol phenol resin. Examples of the urea resin include a polymerization reaction product (dehydration condensation reaction product) such as urea and formaldehyde. Examples of the melamine resin include polymerization reactants such as melamine and formaldehyde.

Examples of the unsaturated polyester resin include a resin obtained by dissolving an unsaturated polyester obtained from an unsaturated polybasic acid or the like and a polyhydric alcohol or the like in a monomer polymerizing the unsaturated polyester resin and curing the unsaturated polyester resin. For example, unsaturated polybasic acids include phthalic acid, isophthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, succinic acid, itaconic acid, citraconic acid and the like, and polyhydric alcohols include polyethylene glycol. , Polypropylene glycol, polyethylene / polypropylene glycol, trimethylolpropane, diethylene glycol, 1,4-butanediol, 1,6-hexaneglycol and the like.

Examples of the silicon resin include those having an organopolysiloxane as a main skeleton.

The amount of these resins to be used with respect to 100 parts by mass of diamond particles is preferably 10 to 200 parts by mass, and more preferably 20 to 100 parts by mass.

<Method of mixing a polishing dispersion and a resin to obtain a polishing resin composition>
As a method of obtaining a polishing resin composition by mixing the polishing dispersion liquid and the resin, the polishing dispersion liquid and the resin may be directly mixed to prepare the polishing resin composition, and the resin and the organic may be prepared in advance. After mixing the solvent, it may be mixed with the polishing dispersion to prepare a polishing resin composition.

The viscosity of the polishing resin composition to be produced is preferably 0.1 cp to 500 cp, more preferably 0.5 cp to 200 cp, and particularly preferably 1.0 cp to 100 cp at room temperature. By using a polishing resin composition having a viscosity in such a range, a polishing sheet having a polishing layer having a desired thickness can be produced.

<Flexible base material>
When the polishing sheet is pressed against the surface to be polished and used, performance such as followability to the surface to be polished and appropriate tensile strength is required. As the shape of the polishing sheet, a tape shape or a disc shape is preferable.

In order to satisfy such performance, the thickness of the flexible base material is preferably 5 μm to 100 μm, more preferably 10 μm to 90 μm, and 20 μm to 80 μm. Is particularly preferable. From the viewpoint of being able to withstand tensile strength and being excellent in followability, it is preferable that the thickness of the flexible base material is within this range.

Examples of the flexible base material include polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acrylic resins such as triacetyl cellulose and methyl methacrylate-based copolymers, styrene resins, polysulfone resins, polyether sulfone resins, and polycarbonate resins. Examples thereof include vinyl chloride resin, polymethacrylicimide resin, polyphenylene sulfide resin, polyamide resin, polyimide resin, polyether ether ketone resin and the like.

As a method of forming a polishing layer on a flexible substrate, an air doctor coat, a blade coat, an air knife coat, a squeeze coat, an impregnation coat, a reverse roll coat, a transfer roll coat, a gravure coat, a kiss coat, a spray coat, and a bar. After coating the polishing resin composition on the flexible base material with a coat, spin coat, etc., the organic solvent in the polishing resin composition is removed and dried to polish the flexible base material. Layers can be formed.
Among these, the bar coating method is preferable because it is possible to easily form a layer having a uniform thickness.

The flexible substrate may be provided with a primer layer between the flexible substrate and the polishing layer in order to improve the adhesion to the polishing layer. Examples of the resin used for the primer layer include COOM, SO ₃ M, OSO ₃ M, P = O (OM) ₃ , OP = O (OM) ₂ (M is a hydrogen atom, an alkali metal base or an amine salt). Polyurethane resin, polyester resin, poly (meth) acrylic resin and the like having one or more functional groups are preferably mentioned.

<Polishing sheet>
The polishing sheet of the present invention is composed of a polishing layer containing diamond particles on the surface of a flexible base material.
The polishing sheet of the present invention has a feature that diamond particles are uniformly dispersed in the state of primary particles. Therefore, by polishing the object to be polished using the polishing sheet of the present invention, it is possible to prevent the object to be polished from having irregularities or scratches. Therefore, the polishing sheet of the present invention can be suitably used as a polishing tape used for finishing of magnetic disks, precision instruments, precision parts, printed circuit boards, etc., and particularly preferably used for polishing the end face finishing process of a silicon wafer. Can be done.

In the polishing sheet of the present invention, the arithmetic mean roughness of the surface of the polishing sheet is preferably 0.05 to 3.0 μm, and more preferably 0.05 to 1.0 μm.
By setting the range to such a range, the object can be smoothly polished in a short time.

The arithmetic mean roughness of the surface of the polishing sheet is measured by a general surface roughness meter such as a laser type or a stylus type.

Hereinafter, the present invention will be described based on examples. The present invention is not limited to the examples and the like. In the examples, "part" represents "part by mass" and "%" represents "% by mass".

(Example 1)
Add 15 parts of a dispersant (DISPERBYK-2013, manufactured by BIC Chemie Japan Co., Ltd., amine value 18 mgKOH / g, acid value 8 mgKOH / g) to 300 parts of methyl ethyl ketone, and stir and mix at 25 ° C. for 10 minutes to make the dispersant uniform. A solution dissolved in was obtained. To the obtained solution, 135 parts of diamond particles (1/4, manufactured by Technorise Co., Ltd., primary particle median diameter 0.22 to 0.28 μm) were added, and an ultrasonic cleaner SU-2TH (manufactured by Shibata Scientific Technology Co., Ltd.) was added. Was irradiated with ultrasonic waves for 30 minutes to obtain 450 parts of a dispersion liquid in which diamond particles were dispersed. Impurities, foreign substances, and residual agglomerated particles were removed from the obtained dispersion through a 0.5 μm membrane filter to obtain a polishing dispersion 1. The content of diamond particles in the polishing dispersion 1 is 30% by mass.

[Measurement of median diameter and standard deviation of diamond particles in polishing dispersion]
The median diameter of the diamond particles in the dispersion liquid 1 for polishing was measured using a Microtrac Nanotrac 150 (manufactured by Nikkiso Co., Ltd., particle size distribution measuring instrument) under the following conditions. Table 1 shows the median diameter and standard deviation of diamond particles.

<Measurement conditions>
Measurement time: 180 seconds Solvent: Methyl ethyl ketone (refractive index (20 ° C.) 1.378)
Particle refractive index: diamond (refractive index 2.42)
Particle density: 3.5 g / cc
Transparency: Transmissive shape: Non-spherical

[Evaluation of dispersion stability of polishing dispersion]
50 parts of the produced dispersion for polishing 1 was stored in a temperature environment of 40 ° C. for 1 week, the median diameter was measured, and then agglomerates were obtained using a 1.0 μm membrane filter. The mass of this agglomerate was measured and the dispersion stability was evaluated. Table 1 shows the evaluation results of dispersion stability.

(Example 2)
In Example 1, "dispersant (DISPERBYK-2013, manufactured by BIC Chemie Japan Co., Ltd., amine value 18 mgKOH / g, acid value 8 mgKOH / g)" was referred to as "dispersant (DISPERBYK-2012, BIC Chemie Japan Co., Ltd.)". A polishing dispersion 2 was prepared in the same manner as in Example 1 except that the amine value was 7 mgKOH / g and the acid value was 7 mgKOH / g, and the dispersion stability of the polishing dispersion 2 was evaluated.

(Example 3)
In Example 1, "dispersant (DISPERBYK-2013, manufactured by BIC Chemie Japan Co., Ltd., amine value 18 mgKOH / g, acid value 8 mgKOH / g)" was replaced with "dispersant (DISPERBYK-2001, BIC Chemie Japan Co., Ltd.). A polishing dispersion 3 was prepared in the same manner as in Example 1 except that the amine value was 29 mgKOH / g and the acid value was 19 mgKOH / g, and the dispersion stability of the polishing dispersion 3 was evaluated.

(Example 4)
In Example 1, "dispersant (DISPERBYK-2013, manufactured by BIC Chemie Japan Co., Ltd., amine value 18 mgKOH / g, acid value 8 mgKOH / g)" was replaced with "dispersant (DISPERBYK-2025, BIC Chemie Japan Co., Ltd.). A polishing dispersion 4 was prepared in the same manner as in Example 1 except that the amine value was 37 mgKOH / g and the acid value was 38 mgKOH / g, and the dispersion stability of the polishing dispersion 4 was evaluated.

(Example 5)
In Example 1, "dispersant (DISPERBYK-2013, manufactured by Big Chemie Japan Co., Ltd., amine value 18 mgKOH / g, acid value 8 mgKOH / g)" was referred to as "dispersant (DISPERBYK-142, Big Chemie Japan Co., Ltd.). A polishing dispersion 5 was prepared in the same manner as in Example 1 except that the amine value was 43 mgKOH / g and the acid value was 46 mgKOH / g, and the dispersion stability of the polishing dispersion 5 was evaluated.

(Example 6)
In Example 1, "dispersant (DISPERBYK-2013, manufactured by BIC Chemie Japan Co., Ltd., amine value 18 mgKOH / g, acid value 8 mgKOH / g)" was replaced with "dispersant (DISPERBYK-162, BIC Chemie Japan Co., Ltd.). The polishing dispersion 6 was prepared in the same manner as in Example 1 except that the amine value was 13 mgKOH / g), and the dispersion stability of the polishing dispersion 6 was evaluated.

(Example 7)
In Example 1, "dispersant (DISPERBYK-2013, manufactured by BIC Chemie Japan Co., Ltd., amine value 18 mgKOH / g, acid value 8 mgKOH / g)" was referred to as "dispersant (BYK-9077, BIC Chemie Japan Co., Ltd.)". , Amine value 48 mgKOH / g) ”was prepared in the same manner as in Example 1, and the dispersion stability of the polishing dispersion 7 was evaluated.

(Comparative Example 1)
In Example 1, a dispersion liquid 8 for polishing was prepared in the same manner as in Example 1 except that ultrasonic cleaner SU-2TH (manufactured by Shibata Scientific Technology Co., Ltd.) was not used to irradiate ultrasonic waves for 30 minutes. The dispersion stability of the polishing dispersion 8 was evaluated.

(Comparative Example 2)
In Example 1, the same as in Example 1 except that the ultrasonic cleaner SU-2TH (manufactured by Sibata Scientific Technology Co., Ltd.) was not irradiated with ultrasonic waves for 30 minutes and the diamond particles were dispersed for 30 minutes by a bead mill. A polishing dispersion 9 was prepared, and the dispersion stability of the polishing dispersion 9 was evaluated.

(Comparative Example 3)
In Example 1, "dispersant (DISPERBYK-2013, manufactured by BIC Chemie Japan Co., Ltd., amine value 18 mgKOH / g, acid value 8 mgKOH / g)" was replaced with "dispersant (DISPERBYK-174, BIC Chemie Japan Co., Ltd.). The polishing dispersion 10 was prepared in the same manner as in Example 1 except that the acid value was 22 mgKOH / g), and the dispersion stability of the polishing dispersion 10 was evaluated.

(Comparative Example 4)
In Example 1, "dispersant (DISPERBYK-2013, manufactured by BIC Chemie Japan Co., Ltd., amine value 18 mgKOH / g, acid value 8 mgKOH / g)" was referred to as "dispersant (DISPERBYK-108, BIC Chemie Japan Co., Ltd.)". The polishing dispersion 11 was prepared in the same manner as in Example 1 except that the amine value was 71 mgKOH / g, and the dispersion stability of the polishing dispersion 11 was evaluated.

(Comparative Example 5)
In Example 1, "dispersant (DISPERBYK-2013, manufactured by BIC Chemie Japan Co., Ltd., amine value 18 mgKOH / g, acid value 8 mgKOH / g)" was referred to as "dispersant (DISPERBYK-140, BIC Chemie Japan Co., Ltd.). A polishing dispersion 12 was prepared in the same manner as in Example 1 except that the amine value was 76 mgKOH / g and the acid value was 73 mgKOH / g, and the dispersion stability of the polishing dispersion 12 was evaluated.

(Comparative Example 6)
In Example 1, "dispersant (DISPERBYK-2013, manufactured by BIC Chemie Japan Co., Ltd., amine value 18 mgKOH / g, acid value 8 mgKOH / g)" was replaced with "dispersant (DISPERBYK-2150, BIC Chemie Japan Co., Ltd.). A polishing dispersion 13 was prepared in the same manner as in Example 1 except that the amine value was 57 mgKOH / g, and the dispersion stability of the polishing dispersion 13 was evaluated.

In Table 1, the polishing dispersion liquid irradiated with ultrasonic waves was marked with ◯, and the polishing dispersion liquid not irradiated with ultrasonic waves was marked with x.

As can be seen from Table 1, when the amine value of the polymer having a basic functional group is 50 mgKOH / g or less in Examples 1 to 7, the median diameter is equivalent to the primary particle diameter of the diamond particles after the polishing dispersion is produced. Is obtained. Further, when the acid value of the polymer having a basic functional group is 50 mgKOH / g or less, a smaller median diameter can be obtained after the dispersion liquid for polishing is produced.
Further, it can be seen that the polishing dispersion, which has been stored in a temperature environment of 40 ° C. for one week, has excellent storage stability because there are few aggregates of diamond particles.
When the dispersion was produced without irradiating ultrasonic waves in Comparative Examples 1 to 6, the dispersion of diamond particles did not proceed sufficiently, and many particles were filtered by filtration during production, and the primary particle diameter of the diamond particles. It was confirmed that the median diameter was larger and the storage stability was inferior. Further, it was also confirmed that when the amine value and the acid value of the polymer having only an acid value or the polymer having a basic functional group were contained at 50 mgKOH / g or more, the median diameter was also large and the storage stability was poor.
From this, it was confirmed that the polishing dispersions of Examples 1 to 7 had a good particle size distribution and storage stability.

[Surface observation of dispersion by SEM]
SEM photographs (magnification: 10,000 times) of the dispersions of Examples 1 to 7 and Comparative Examples 1 to 6 were taken by the cryo-SEM method using MP-Z08181T manufactured by JEOL Ltd. In the dispersions of Examples 1 to 7, a large number of single particles were observed and passed. On the other hand, in the dispersions of Comparative Examples 1 to 6, the particles seemed to be associated and were rejected.

Here, with respect to the dispersions of Example 1 and Comparative Example 1, the SEM photographs taken are shown in FIGS. 1 and 2.

(Example 8)
Forty-three parts of a polyester resin (Elitel UE-9200, manufactured by Unitika Ltd.) was added to 100 parts of cyclohexanone, and the mixture was stirred and mixed at 25 ° C. for 1 hour or more to obtain a solution in which the resin was uniformly dissolved. 415 parts of the produced polishing dispersion 1 is mixed with 143 parts of the obtained solution, uniformly applied to a polyester film (thickness 50 μm) using a bar coater, placed in a blower dryer, and dried at a temperature of 100 ° C. for 1 minute. After drying, a polishing sheet having a polishing layer thickness of 3 μm was obtained.

<Evaluation method of polishing sheet>
Using the prepared polishing sheet, the surface of a 4-inch silicon substrate for a semiconductor device that had been roughly polished in advance was polished while rotating, and the average surface roughness (Ra) was measured and the appearance was observed.
The average surface roughness (Ra) of the silicon substrate was measured using a stylus type surface shape measuring instrument (Dektake 6M, manufactured by ULVAC, Inc.) under the following conditions.

<Measurement conditions>
Touch radius: 12.5 μm
Measurement distance: 1000 μm
Measurement time: 20 seconds Stylus pressure: 5 mg
Measuring range: 6.5 μm

<Polishing conditions>
Average Surface Roughness (Ra) of Silicon Substrate Before Polishing: 31.6 nm
Silicon substrate rotation speed: 500 rotations Tape pressing pressure: 1 kg / cm ²

<Rate of change>
The rate of change was calculated by the following formula.
Rate of change = [(Average surface roughness after polishing)-(Average surface roughness before polishing)] / (Average surface roughness before polishing)

(Examples 9 to 14 and Comparative Examples 7 to 12)
Example 1 to Example 1 to Example 14 and Comparative Example 7 to 12 respectively, except that the polishing dispersion 2 to the polishing dispersion 13 were used instead of the polishing dispersion 1 in Example 1, respectively. A polishing sheet was prepared and evaluated in the same manner as in the above. The evaluation results are shown in Table 2.

As can be seen from Table 2, since the polishing sheets of Examples 8 to 14 have a small median diameter of diamond particles and are difficult to aggregate, the surface roughness of the silicon substrate after the polishing test and before polishing is reduced (improved). It was confirmed that
On the other hand, since the polishing sheets of Comparative Examples 7 to 12 have a large median diameter of diamond particles and are easily aggregated, the surface roughness of the silicon substrate before polishing after the polishing test increases (deteriorates), and precision polishing can be performed. It was confirmed that it was not progressing.
It was confirmed that the polishing sheets of Examples 8 to 14 according to the present invention had good polishing performance and did not cause unevenness or defective scratches due to agglomerated particles.

<Surface observation of polishing sheet by SEM>
SEM photographs (magnification: 30,000 times) of the surface of the polishing layer in the polishing sheets of Examples 8 to 14 and Comparative Examples 7 to 12 were taken by FE-SEM (field emission scanning electron microscope, ULTRA55 manufactured by Carl Zeiss). In the polishing sheets of Examples 8 to 14, the particles were densely distributed and passed. On the other hand, in the polishing sheets of Comparative Examples 7 to 12, the particles were sparsely distributed and failed.

Here, with respect to the polishing sheets of Example 8 and Comparative Example 7, SEM photographs of the surface of the polishing layer taken are shown in FIGS. 3 and 4.

The polishing dispersion and polishing sheet obtained by the present invention can be suitably used for finishing of magnetic disks, precision instruments, precision parts, printed circuit boards, and the like.

Claims (5)

A mixed solution containing diamond particles having a median diameter of 0.1 to 5.0 μm as primary particles and a polymer having a basic functional group having an amine value of 1.0 to 50 mgKOH / g in an organic solvent. The process of getting
The step of irradiating the mixed solution with ultrasonic waves,
A method for producing a dispersion liquid for polishing, which comprises. The method for producing a dispersion for polishing according to claim 1, wherein the acid value of the polymer having a basic functional group is 1.0 to 50 mgKOH / g. It should contain at least an organic solvent, diamond particles having a median diameter of 0.1 to 5.0 μm as primary particles, and a polymer having a basic functional group having an amine value of 1.0 to 50 mgKOH / g. A characteristic dispersion for polishing. The polishing dispersion according to claim 3, wherein the standard deviation of the median diameter of the diamond particles is 0.01 to 5.0. The polishing dispersion according to claim 3 or 4, wherein the polymer having a basic functional group has an acid value of 1.0 to 50 mgKOH / g.

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