JP2012049477A - Polishing method of compound semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing method exhibiting an excellent polishing rate while suppressing polishing scratch when a compound semiconductor wafer is polished.SOLUTION: In the polishing method of polishing a compound semiconductor wafer by using an abrasive material and a slurry containing abrasive grains, the abrasive material contains a nonwoven fabric consisting of extra fine single fibers having an average cross-sectional area of 0.01-30 μmand a polymer elastic body in such a range as the mass ratio of nonwoven fabric/polymer elastic body falls within a range of 90/10-55/45, and has an apparent density of 0.70-1.2 g/cmand JIS hardness of 45D-75D. The abrasive grains have a mean particle diameter of 0.01-20 μm.

Description

  The present invention relates to a compound semiconductor wafer polishing method and a compound semiconductor wafer manufacturing method using the polishing method.

In recent years, with high integration of integrated circuits and multilayer wiring, compound semiconductor wafers on which integrated circuits are formed are required to have high precision flatness. As a polishing method for polishing a compound semiconductor wafer, chemical mechanical polishing (CMP) is known. CMP is a method of polishing the surface of a substrate to be polished with an abrasive (pad) while dropping slurry of abrasive grains.
On the other hand, in order to flatten a wafer such as SiC or GaAs after grinding, the wafer is polished by supplying and spraying abrasive grains having high mechanical elements such as diamond and alumina on the abrasive. That is, for polishing compound semiconductor wafers such as SiC and GaAs, a polishing cloth using a woven cloth made of rayon or the like is used, but depending on the type of abrasive grains, the occurrence of polishing flaws may increase. It has been difficult to achieve both reduction in polishing efficiency and surface finish roughness and reduction in polishing scratches.
On the other hand, with respect to the nonwoven fabric type polishing cloth, in recent years, a nonwoven fabric type polishing pad obtained by using a nonwoven fabric formed from an ultrafine fiber bundle for the purpose of obtaining higher planarization performance is known (for example, The following patent documents 1 to 4). Specifically, for example, Patent Document 1 includes as a main component a nonwoven fabric in which polyester microfiber bundles having an average fineness of 0.0001 to 0.01 dtex are intertwined and polyurethane existing in the interior space of the nonwoven fabric. A polishing pad made of a sheet-like material composed of a polymer elastic body is described. According to such a polishing pad, it is described that polishing processing with higher accuracy than before can be realized.

However, in the polishing pads as described in Patent Documents 1 to 4, since the nonwoven fabric obtained by needle punching the ultrafine fibers with small fineness is used, the apparent density is low and the porosity is low. It was also expensive. For this reason, only a soft and low-rigidity polishing pad can be obtained. Therefore, polishing with a high mechanical element cannot withstand long-time polishing. As described above, the polishing pad has a problem such as a short life, and thus has not been adopted except for the finish polishing process.
In addition, Patent Documents 5 to 7 do not clearly describe the use of a nonwoven fabric as an abrasive, although there is a description of additives added to abrasive grains when polishing a compound semiconductor such as SiC.

JP 2007-54910 A JP 2003-170347 A JP 2004-130395 A JP 2002-172555 A Japanese Patent Laid-Open No. 2005-117027 JP 2008-280207 A JP 2009-238891 A

  An object of the present invention is to provide a polishing method that is excellent in polishing rate and does not easily cause polishing scratches (hereinafter also referred to as scratches) in polishing a compound semiconductor wafer.

The inventors of the present invention have solved the above problems by using a specific abrasive and a specific abrasive in combination in polishing a compound semiconductor wafer. That is, the present invention includes a polishing material, a polishing method of polishing a compound semiconductor wafer using a slurry containing abrasive grains, the abrasive has an average cross-sectional area is 0.01 [mu] m ² 30 .mu.m ² ultrafine A non-woven fabric made of a single fiber and a polymer elastic body are included in a range where the mass ratio of the nonwoven fabric / polymer elastic body is 90/10 to 55/45, and 0.70 g / cm ^{3 to} 1.2 g / cm ^3. And an JIS hardness of 45D to 75D, and the abrasive grains have an average particle diameter of 0.01 μm to 20 μm.

  According to the polishing method of the present invention, in compound semiconductor wafer polishing, a compound semiconductor wafer having an excellent polishing rate and suppressing generation of scratches can be obtained.

Hereinafter, the present invention will be described in detail based on embodiments. In addition, this invention is not limited at all by embodiment described below.
The polishing method of this embodiment is a method of polishing a compound semiconductor wafer using a polishing material and a slurry containing abrasive grains (hereinafter also referred to as “abrasive slurry”). As a specific example, for example, a method of polishing a compound semiconductor wafer by chemical mechanical polishing (hereinafter also referred to as CMP) by flowing an abrasive slurry between an abrasive and a compound semiconductor wafer. Is mentioned.

Hereinafter, each component of the present embodiment will be described in detail.
1. Abrasive polishing material present embodiment, the nonwoven fabric and the elastic polymer consisting of ultrafine single fiber average cross-sectional area is 0.01 [mu] m ² 30 .mu.m ^2, the weight ratio of the nonwoven fabric / elastic polymer 90/10 In the range of 55/45. The polishing material of the present embodiment has a JIS hardness of apparent density and 45D~75D of ^{0.70g / cm 3 ~1.2g / cm 3} .

The abrasive of this embodiment has a structure in which a nonwoven fabric is filled with a polymer elastic body and combined. The polymer elastic body is preferably impregnated in the nonwoven fabric.
The abrasive of the present embodiment has a higher volume ratio (abrasive filling rate) of the portion excluding the voids, that is, the porosity is low, as compared with conventionally known general abrasives.
Although the abrasive filling rate of this embodiment is not particularly limited, it is preferably in the range of 55 to 95%, more preferably in the range of 60 to 90%. When the abrasive filling rate is less than 55%, the polishing rate, the planarization performance, and the polishing stability are lowered. On the other hand, when the abrasive filling rate exceeds 95%, the polishing rate decreases because the retention of the abrasive slurry decreases. Further, since the rigidity of the abrasive becomes too high, it becomes difficult to follow the warpage and undulation of the surface of the substrate to be polished, resulting in increased occurrence of polishing scratches and flatness over the entire surface of the substrate to be polished. The sex will be reduced.
The abrasive filling rate is the apparent density of the abrasive, and the density (theoretical density) when the porosity is 0% is calculated from the constituent ratio of each constituent material of the abrasive and the respective density. It can be calculated by the formula “apparent density of abrasive / theoretical density × 100 (%)”.

Although the abrasive of this embodiment contains the nonwoven fabric and polymer elastic body which consist of an ultrafine single fiber, it is preferable that the said ultrafine single fiber is converged by the said polymer elastic body, and forms the fiber bundle. Since the fiber bundle formed by bundling ultrafine single fibers exists in a state like a single thick fiber, the rigidity of the abrasive is increased. When the ultrafine single fibers are not bundled, the ultrafine single fibers are flexible, so that high flattening performance cannot be obtained. In addition, the number of missing fibers increases, and the abrasive grains tend to aggregate on the missing fibers, thereby easily causing polishing flaws.
Here, the fact that the ultrafine single fibers are focused means a state in which most of the ultrafine single fibers existing inside the fiber bundle are bonded and restrained by the polymer elastic body existing inside the fiber bundle.

The abrasive in the present embodiment preferably contains a fiber bundle having a cross-sectional area of 40 μm ² or more. By including such a thick fiber bundle, the rigidity of the nonwoven fabric can be further increased. The cross-sectional area of the fiber bundle is the total area of the cross section made of the ultrafine single fibers constituting the fiber bundle and the polymer elastic body existing inside the fiber bundle in the fiber bundle cross section.
Further, the number of fiber bundles per unit area existing in the cross section in the thickness direction of the nonwoven fabric is not particularly limited, but is preferably 600 bundles / mm ² or more, more preferably 1000 bundles / mm ² or more, It is preferably 4000 bundles / mm ² or less, and more preferably 3000 bundles / mm ² or less. When it is 4000 bundles / mm ² or less, the abrasive grains are sufficiently retained on the surface of the abrasive and the polishing rate is likely to be improved.

  As described above, in the embodiment of the present invention, the abrasive filling rate is preferably in the range of 55 to 95%. Thus, the fiber bundles are present at a high density, so that the surface of the abrasive is polished during polishing. When the exposed fiber bundle is split or fibrillated, ultrafine single fibers are formed, whereby the retainability of the abrasive grains is enhanced and the surface becomes flexible, and the generation of polishing flaws is suppressed. Moreover, since the porosity of an abrasive can be lowered by this, the rigidity of the abrasive is increased.

The average length of the fiber bundle is not particularly limited, but 100 mm or more, and further 200 mm or more can easily increase the fiber density of the ultrafine single fiber, and can easily increase the rigidity of the abrasive. It is preferable from the point which can do, and the point which can suppress the omission of a fiber. When the length of the fiber bundle is too short, it is difficult to increase the density of the ultrafine single fibers and a sufficiently high rigidity cannot be obtained, and the ultrafine single fibers are easily removed during polishing. The upper limit is not particularly limited. For example, in the case where the abrasive contains a long fiber web produced by a spunbond method, which will be described later, as long as it is not physically cut, it is several meters, several hundred meters, several kilometers or A fiber bundle having a longer fiber length may be included.
The plurality of fiber bundles are preferably bound together by a polymer elastic body existing outside the fiber bundle and exist in a lump shape. Thus, by binding the fiber bundles together,
The form stability of the abrasive is improved, and the polishing stability is improved.

The ratio of the nonwoven fabric to the polymer elastic body in the abrasive of the present embodiment is 90/10 to 55/45 in terms of mass ratio, and if within this range, the cross-sectional area of the fiber bundle can be easily increased, Since the density of the ultrafine single fibers exposed on the surface of the abrasive can be sufficiently increased, the polishing stability, the polishing rate and the flatness performance can be further improved. The ratio is preferably in the range of 85/15 to 65/35.
When the mass ratio of the polymer elastic body is less than 10, since the fiber bundle is not sufficiently fixed, the change in the shape of the abrasive is reduced, so that the polishing rate is lowered. Also, polishing scratches increase. On the other hand, when the mass ratio of the polymer elastic body exceeds 45, it becomes difficult to hold the abrasive grains on the surface or inside of the abrasive and the polishing rate is lowered.

The apparent density of the abrasive of this embodiment is 0.7 g / cm ^{3 to} 1.2 g / cm ³ , and within this range, the rigidity is excellent and the polishing rate is excellent. The apparent density is preferably in the range of ^{0.8g / cm 3 ~1.2g / cm 3} .

Moreover, the JIS-D hardness [D (23 degreeC, dry)] in 23 degreeC of the abrasive | polishing material of this embodiment is 45D-75D. The D hardness [D (23 ° C., dry)] is preferably about 50D to 70D. If the D hardness [D (23 ° C., dry)] is too high, polishing flaws are likely to occur, and if it is too low, the planarization performance tends to decrease.
Note that the abrasive of this embodiment has a soft surface compared to an abrasive that does not contain ultrafine single fibers because the ultrafine single fibers are formed on the surface with a high fiber density. Therefore, even if the D hardness is increased, scratches are hardly generated.

In the abrasive of this embodiment, the weight loss due to Taber abrasion (wear wheel H-22, load 500 g, 1000 times) is not particularly limited, but is preferably 150 mg or less, more preferably 100 mg or less. preferable. When the wear loss is too large, the fibers are likely to come off, and as a result, the polishing stability is lowered, and scratches are likely to occur due to the dropped fibers. In addition, the life of the abrasive is shortened.
The abrasive according to the present embodiment can appropriately adjust the wear loss by adjusting the ratio of the nonwoven fabric made of a bundle of ultrafine single fibers with a high density of fibers that are hard to wear and the polymer elastic body. .

The polishing material of the present embodiment is obtained by subjecting the polishing material to a flattening process by buffing or the like, a seasoning process (conditioning process) before polishing using conditioning of an abrasive material such as diamond, or a dressing process at the time of polishing. By dividing or fibrillating a fiber bundle existing in the vicinity of the surface, ultrafine single fibers can be formed on the surface of the abrasive.
The fiber density of the ultrafine single fiber on the surface of the abrasive is not particularly limited, but is preferably 600 fibers / mm ² or more, more preferably 1000 fibers / mm ² or more, and 2000 fibers / mm ² or more. Is more preferable. When the fiber density is too low, the retention of abrasive grains tends to be insufficient. The upper limit of the fiber density is not particularly limited, but is preferably about 1,000,000 pieces / mm ² from the viewpoint of productivity.
Further, the ultrafine single fiber on the surface of the abrasive may be raised or not raised. When the ultrafine single fibers are raised, the surface of the abrasive becomes more flexible, so that the effect of reducing polishing scratches is further increased. On the other hand, when the degree of napping of the ultrafine single fiber is low, it is advantageous for applications in which microflatness is important. Thus, it is preferable to appropriately select the surface state according to the application.

1-1. Nonwoven nonwoven fabric contained in the polishing material of this embodiment is composed of ultrafine single fiber average cross-sectional area is in the range of 0.01 [mu] m ² 30 .mu.m ^2. The average cross-sectional area is preferably in the range of 0.1μm ² ~20μm ^2. When the average cross-sectional area of the ultrafine single fibers is less than 0.01 μm ² , the ultrafine single fibers near the surface of the nonwoven fabric are not sufficiently separated, and as a result, the holding power of the abrasive slurry is reduced. On the other hand, when the average cross-sectional area of the ultrafine fibers exceeds 30 μm ² , the surface of the nonwoven fabric becomes too rough and polishing scratches are likely to occur.

  Specific examples of the ultrafine fibers constituting the nonwoven fabric of the present embodiment include, for example, polyethylene terephthalate (PET), isophthalic acid modified polyethylene terephthalate, sulfoisophthalic acid modified polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, and the like. Aromatic polyester fiber; aliphatic polyester fiber formed from polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polyhydroxybutyrate-polyhydroxyvalerate copolymer, etc .; polyamide 6, polyamide 66, polyamide 10, polyamide 11, polyamide 12, polyamide 6-12, etc .; polyamide fiber; polypropylene, polyethylene, polybutene, poly Polyolefin fibers such as tilpentene and chlorinated polyolefins; modified polyvinyl alcohol fibers formed from modified polyvinyl alcohol containing 25 to 70 mol% of ethylene units; formed from elastomers such as polyurethane elastomers, polyamide elastomers, and polyester elastomers Elastomer fibers; vinylon fibers; and acrylic fibers. These may be used alone or in combination of two or more.

Among the ultrafine fibers, fibers having a glass transition temperature (T _g ) of 50 ° C. or higher are preferable, and fibers of 60 ° C. or higher are more preferable. Further, a fiber having a water absorption rate of 4% by mass or less is preferable, and a fiber of 2% by mass or less is more preferable.
When the glass transition temperature of the ultrafine single fiber is within such a range, the polishing material can maintain higher rigidity, so that the flattening performance is further improved. Thus, a polishing material excellent in polishing stability and polishing uniformity can be obtained. The upper limit of the glass transition temperature is not particularly limited.

Moreover, when the water absorption rate of the ultrafine single fiber is 4% by mass or less, a decrease in rigidity of the abrasive over time is suppressed even during polishing. Accordingly, it is possible to obtain an abrasive that suppresses a decrease in lapping performance with time, and is less susceptible to fluctuations in basic lapping characteristics such as a polishing rate, polishing nonuniformity, and polishing scratches.
Specific examples of such ultrafine single fibers include, for example, polyethylene terephthalate (PET, T _g 77 ° C., water absorption 1% by mass), isophthalic acid-modified polyethylene terephthalate (T _g 67-77 ° C., water absorption 1% by mass). , Sulfoisophthalic acid modified polyethylene terephthalate (T _g 67-77 ° C., water absorption 1-4% by mass), polybutylene naphthalate (T _g 85 ° C., water absorption 1% by mass), polyethylene naphthalate (T _g 124 ° C., aromatic polyester fibers formed from water absorption 1% by weight) and the like; terephthalic acid and nonanediol and methyl octanediol copolyamide (T _g 125~140 ℃, formed from water absorption 1-4 wt%), etc. And semi-aromatic polyamide fibers.
In particular, modified PET, such as PET and isophthalic acid-modified PET, is dense and dense in order to be greatly crimped in a wet heat treatment process for forming ultrafine single fibers from a web-entangled sheet composed of sea-island type composite fibers described later. It is also preferable from the viewpoints that a nonwoven fabric can be formed, that the rigidity of the abrasive is easily increased, and that changes with time due to moisture hardly occur during polishing.

1-2. Polymer elastic body The polymer elastic body contained in the abrasive of the present embodiment contains a resin. The resins contained in the polymer elastic body may be used alone or in combination of two or more.
Specific examples of the resin include, for example, polyurethane resins, polyamide resins, (meth) acrylic acid ester resins, (meth) acrylic acid ester-styrene resins, (meth) acrylic acid ester-acrylonitrile resins, ( (Meth) acrylic ester-olefin resin, (meth) acrylic ester- (hydrogenated) isoprene resin, (meth) acrylic ester-butadiene resin, styrene-butadiene resin, styrene-hydrogenated isoprene resin , Acrylonitrile-butadiene resin, acrylonitrile-butadiene-styrene resin, vinyl acetate resin, (meth) acrylic ester-vinyl acetate resin, ethylene-vinyl acetate resin, ethylene-olefin resin, silicone resin, fluorine Resin and polyester tree And the like.

The resin contained in the polymer elastic body of the present embodiment is preferably a resin that crystallizes or aggregates by hydrogen bonding, such as a polyurethane resin, a polyamide resin, and a polyvinyl alcohol resin. The polymer elastic body containing such a resin is excellent in adhesiveness for focusing ultrafine single fibers or binding fiber bundles. In addition, the hardness of the abrasive is increased, the stability over time in polishing is excellent, and the loss of fibers is also suppressed.
Among the above resins, polyurethane resins are preferred because of the rigidity of the abrasive, the wettability, and the stability over time at the time of polishing, and a polyalkylene glycol having a carboxyl group, a sulfonic acid group, and a carbon number of 3 or less. A polyurethane resin having at least one hydrophilic group selected from the group consisting of groups is particularly preferred.
Of the polyurethane resins, water-dispersible polyurethane resins are preferable. A water-dispersible polyurethane resin has a high concentration, a low viscosity, and an excellent impregnation permeability. Moreover, the adhesiveness with respect to a fiber is also excellent.

Below, the case where a polyurethane-type resin is used as resin contained in a polymer elastic body is demonstrated in detail as a representative example.
Examples of the polyurethane resin include various polyurethane resins obtained by reacting a polymer polyol having an average molecular weight of 200 to 6000, an organic polyisocyanate, and a chain extender in a predetermined molar ratio.

Specific examples of the polymer polyol include, for example, polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (methyltetramethylene glycol) and copolymers thereof; polybutylene adipate diol, polybutylene seba Polyester polyols such as keto diol, polyhexamethylene adipate diol, poly (3-methyl-1,5-pentylene adipate) diol, poly (3-methyl-1,5-pentylene sebacate) diol, polycaprolactone diol And copolymers thereof; polyhexamethylene carbonate diol, poly (3-methyl-1,5-pentylene carbonate) diol, polypentamethylene carbonate diol, polytetramethylene Polycarbonate polyols and copolymers thereof, such as turbo sulfonate diol; polyester carbonate polyols and the like. If necessary, a trifunctional alcohol such as trimethylolpropane or a polyfunctional alcohol such as tetrafunctional alcohol such as pentaerythritol, or ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol. Etc. You may use together short chain alcohols, such as. These may be used alone or in combination of two or more.
In particular, the use of amorphous polycarbonate polyols, alicyclic polycarbonate polyols, linear polycarbonate polyols, and mixtures of these polycarbonate polyols with polyether polyols or polyester polyols are resistant to water. This is preferable because an abrasive having excellent durability such as decomposability and oxidation resistance can be obtained.
In addition, a polyurethane resin containing a polyalkylene glycol group having 5 or less carbon atoms, particularly 3 or less carbon atoms is preferable from the viewpoint of particularly good wettability with water.

Specific examples of the organic polyisocyanate include non-yellowing diisocyanates such as aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 4,4′-dicyclohexylmethane diisocyanate; 2,4- Examples thereof include aromatic diisocyanates such as tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, and xylylene diisocyanate polyurethane. Moreover, you may use together polyfunctional isocyanates, such as trifunctional isocyanate and tetrafunctional isocyanate, as needed. These may be used alone or in combination of two or more.
Among these, 4,4′-dicyclohexylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, and xylylene diisocyanate have high adhesion to fibers, Moreover, it is preferable from the point from which an abrasive | polishing material with high hardness is obtained.

Specific examples of the chain extender include, for example, diamines such as hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylylenediamine, isophoronediamine, piperazine and derivatives thereof, adipic acid dihydrazide, and isophthalic acid dihydrazide. Triamines such as diethylenetriamine; tetramines such as triethylenetetramine; ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-bis (β-hydroxyethoxy) benzene, 1, Diols such as 4-cyclohexanediol; Triols such as trimethylolpropane; Pentaols such as pentaerythritol; Aminoethyl alcohol, Aminopropyl alcohol Amino alcohols such as such as Le and the like. These may be used alone or in combination of two or more.
Among these, it is preferable to use a combination of two or more of hydrazine, piperazine, hexamethylenediamine, isophoronediamine and derivatives thereof, and triamines such as ethylenetriamine from the viewpoint of completing the curing reaction in a short time.
In addition, during the chain extension reaction, together with the chain extender, monoamines such as ethylamine, propylamine, and butylamine; carboxyl group-containing monoamine compounds such as 4-aminobutanoic acid and 6-aminohexanoic acid; methanol, ethanol, propanol, butanol, etc. Monools may be used in combination.

  In addition, a polyurethane containing a carboxyl group-containing diol such as 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butanoic acid, 2,2-bis (hydroxymethyl) valeric acid, etc. By introducing an ionic group such as a carboxyl group into the skeleton of the resin, the wettability to water can be further improved.

  Moreover, in order to control the water absorption rate and storage elastic modulus of the polymer elastic body, a crosslinking agent containing two or more functional groups capable of reacting with the functional group of the monomer unit forming the polyurethane, or polyisocyanate It is preferable to form a crosslinked structure by adding a self-crosslinking compound such as a compound based on polyfunctional block isocyanates.

As a combination of the functional group of the monomer unit and the functional group of the crosslinking agent, carboxyl group and oxazoline group, carboxyl group and carbodiimide group, carboxyl group and epoxy group, carboxyl group and cyclocarbonate group, carboxyl group and aziridine group, Examples thereof include a carbonyl group and a hydrazine derivative or a hydrazide derivative. Among these, a combination of a monomer unit having a carboxyl group and a crosslinking agent having an oxazoline group, a carbodiimide group or an epoxy group, a combination of a monomer unit having a hydroxyl group or an amino group and a crosslinking agent having a blocked isocyanate group, and carbonyl A combination of a monomer unit having a group and a hydrazine derivative or a hydrazide derivative is particularly preferred because crosslinking is easy and the resulting abrasive has excellent rigidity and wear resistance.
The crosslinked structure is preferably formed in the heat treatment step after applying the polyurethane resin to the nonwoven fabric from the viewpoint of maintaining the stability of the aqueous liquid of the polymer elastic body. Among these, a carbodiimide group and / or an oxazoline group are particularly preferable because they are excellent in crosslinking performance and pot life of an aqueous liquid and have no problem in safety.
Examples of the crosslinking agent having a carbodiimide group include water-dispersed carbodiimide compounds such as “Carbodilite E-01”, “Carbodilite E-02”, and “Carbodilite V-02” manufactured by Nisshinbo Industries, Ltd.
Examples of the crosslinking agent having an oxazoline group include water-dispersed oxazoline compounds such as “Epocross K-2010E”, “Epocross K-2020E”, and “Epocross WS-500” manufactured by Nippon Shokubai Co., Ltd.
As a compounding quantity of a crosslinking agent, it is preferable that the active ingredient of a crosslinking agent is 1-20 mass% with respect to a polyurethane resin, It is more preferable that it is 1.5-1 mass%, 2-10 mass% More preferably.

  In addition, from the viewpoint of enhancing the adhesion to the ultrafine single fiber and increasing the rigidity of the fiber bundle, the content of the polymer polyol component in the polyurethane resin is 65% by mass or less, and further 60% by mass or less. preferable. Moreover, it is preferable from the point which can suppress generation | occurrence | production of a scratch by providing moderate elasticity that it is 40 mass% or more, and also 45 mass% or more.

  In addition, polymer elastic bodies are penetrants, antifoaming agents, lubricants, water repellents, oil repellents, thickeners, extenders, curing accelerators, antioxidants, ultraviolet absorbers, fluorescent agents, antifungal agents, You may further contain foaming agents, water-soluble polymer compounds, such as polyvinyl alcohol and carboxymethylcellulose, dyes, pigments, and inorganic fine particles.

Although the water absorption rate of the polymer elastic body of this embodiment is not specifically limited, It is preferable that it is 0.5-8 mass%, and it is more preferable that it is 1-6 mass%. When the water absorption rate of the polymer elastic body is within such a range, it is possible to maintain high wettability of the abrasive slurry with respect to the abrasive during polishing and to reduce the rigidity of the abrasive over time. It can be suppressed more. Thereby, a high polishing rate and polishing nonuniformity can be maintained.
The water absorption rate of the elastic polymer is the water absorption rate when the dried resin film is immersed in water at room temperature and swelled in saturation. When the polymer elastic body contains two or more kinds of resins, the absorption rate of the polymer elastic body is theoretically calculated as the sum of values obtained by multiplying the water absorption rate of each resin by the mass fraction.

The polymer elastic body having such a water absorption rate can be obtained by adjusting the crosslinking density of the resin contained in the polymer elastic body, introducing a hydrophilic functional group into the resin, or the like.
Specifically, for example, at least one hydrophilic group selected from the group consisting of a carboxyl group, a sulfonic acid group, and a polyalkylene glycol group having 3 or less carbon atoms is introduced into a resin contained in the polymer elastic body. Thus, the water absorption and hydrophilicity of the polymer elastic body can be adjusted. Thereby, the wettability with respect to the abrasive slurry of the abrasive during polishing can be improved.
Such a hydrophilic group can be introduced into the resin by copolymerizing a monomer component having a hydrophilic group as a monomer component for producing a resin contained in the polymer elastic body. The copolymerization ratio of the monomer component having such a hydrophilic group is 0.1 to 20% by mass, and further 0.5 to 10% by mass while minimizing swelling and softening due to water absorption. From the point that water absorption and wettability can be improved.

The storage elastic modulus [E ′ (150 ° C., dry)] at 150 ° C. of the polymer elastic body is not particularly limited, but is preferably 0.1 to 100 MPa, and more preferably 1 to 80 MPa. A polymer elastic body having such a storage elastic modulus [E ′ (150 ° C., dry)] can be obtained by forming a crosslinked structure in a resin contained in the polymer elastic body. When the resin contained in the polymer elastic body has a hydrophilic group, the polymer elastic body is likely to swell with water and the water absorption rate may be too high. In such a case, the water absorption rate can be controlled by adjusting the crosslinking density.
When the polymer elastic body contains two or more kinds of resins, the storage elastic modulus [E ′ (150 ° C., dry)] of the polymer elastic body is the storage elastic modulus [E ′ (150) of each resin. C, dry)] is theoretically calculated as the sum of values obtained by multiplying the mass fraction.

1-3. Next, an example of the manufacturing method of the abrasive according to the present embodiment will be described in detail.
The abrasive of this embodiment is, for example,
(1) A web production process for producing a long fiber web comprising sea-island type composite fibers obtained by melt spinning a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin,
(2) A web entanglement step of forming a web entanglement sheet by overlapping and intertwining a plurality of the long fiber webs;
(3) a wet heat shrinkage treatment step for wet heat shrinkage of the web entangled sheet;
(5) In the ultrafine fiber forming step (5), the ultrafine fiber forming step of forming ultrafine single fibers by dissolving the water-soluble thermoplastic resin in the web entangled sheet in hot water; A polymer elastic body filling step of impregnating a web entangled sheet from which a water-soluble thermoplastic resin has been removed with an aqueous liquid of a polymer elastic body and drying and solidifying it,
It can obtain by the manufacturing method of an abrasive | polishing material provided with these. As another example, in addition to the above steps (1) to (3) and (5) to (6), the abrasive of the present embodiment is
(4) A fiber bundle binding step of binding a fiber bundle by impregnating and drying and solidifying an aqueous liquid of a polymer elastic body to the web entangled sheet contracted in the wet heat contraction processing step (3),
It can obtain by the manufacturing method of an abrasive | polishing material provided with these.

  In the above manufacturing method, the web entangled sheet containing the long fibers is subjected to the heat and heat shrinkage process, so that the web entangled sheet is largely contracted as compared with the case where the web entangled sheet containing the short fibers is subjected to the heat and heat shrinkage. As a result, the fiber density of the ultrafine single fiber becomes dense. And an ultrafine fiber bundle is formed by melt-extracting the water-soluble thermoplastic resin of a web entanglement sheet. At this time, voids are formed in the portion where the water-soluble thermoplastic resin is dissolved and extracted. Before dissolving and extracting the water-soluble thermoplastic resin of the web-entangled sheet, the web-entangled sheet is impregnated with an aqueous liquid of a polymer elastic body and dried and solidified. After the plastic resin is dissolved and extracted, the formed voids are impregnated with an aqueous liquid of a polymer elastic body and dried and solidified so that the ultrafine single fibers constituting the ultrafine fiber bundles are focused and the ultrafine fiber bundles are also focused. Is done. In this way, an abrasive having a high fiber density, a low porosity, and a high rigidity in which ultrafine fibers are converged is obtained.

Each step will be described in detail below.
(1) Web manufacturing process In this process, first, a long fiber web made of sea-island composite fibers obtained by melt spinning a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin is manufactured.

The sea-island type composite fiber is obtained by melt spinning each of a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin having low compatibility with the water-soluble thermoplastic resin, and then combining them. Then, the ultrafine single fiber is formed by dissolving or removing the water-soluble thermoplastic resin from the sea-island type composite fiber thus obtained in the ultrafine fiber forming step (5). The thickness of the sea-island type composite fiber is preferably 0.5 to 3 dtex from the viewpoint of industrial properties.
In this embodiment, the sea-island type composite fiber will be described in detail as a composite fiber for forming an ultrafine single fiber. However, a known ultrafine fiber generating fiber such as a multilayer laminated cross-section fiber is used instead of the sea-island type fiber. It may be used.

  The water-soluble thermoplastic resin is preferably a thermoplastic resin that can be dissolved or removed by water, an alkaline aqueous solution, an acidic aqueous solution, or the like and that can be melt-spun. Specific examples of such a water-soluble thermoplastic resin include, for example, polyvinyl alcohol resins (PVA resins) such as polyvinyl alcohol and polyvinyl alcohol copolymers; copolymers of polyethylene glycol and / or alkali metal sulfonates. Modified polyesters contained as components; polyethylene oxide and the like. Among these, PVA-based resins are particularly preferably used for the following reasons.

  When the sea-island type composite fiber having a PVA resin as a water-soluble thermoplastic resin component is used, the ultrafine single fiber formed by dissolving the PVA resin in the ultrafine fiber forming step (5) is greatly crimped. As a result, a nonwoven fabric having a high fiber density can be obtained. Moreover, when the sea-island type composite fiber which uses PVA-type resin as a water-soluble thermoplastic resin component is used, when PVA-type resin is dissolved in ultrafine fiber formation process (5), it is formed in ultrafine fiber formation process (5). Since the ultrathin single fiber and the polymer elastic body filled in the fiber bundle binding step (4) are not substantially decomposed or dissolved, the physical properties of the ultrafine single fiber or the polymer elastic body are hardly lowered. Furthermore, the environmental load is small.

  The PVA-based resin can be obtained by saponifying a copolymer mainly composed of vinyl ester units. Specific examples of vinyl monomers for forming the vinyl ester unit include, for example, vinyl acetate, vinyl formate, vinyl propionate, vinyl valelate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, Examples include vinyl pivalate and vinyl versatate. These may be used alone or in combination of two or more. Among these, vinyl acetate is preferable from the viewpoint of industrial properties.

The PVA-based resin may be a homo PVA composed only of vinyl ester units or a modified PVA containing a comonomer unit other than the vinyl ester unit as a constituent unit. Modified PVA is more preferable from the viewpoint of controlling melt spinnability, water solubility, and fiber properties.
Specific examples of the comonomer unit other than the vinyl ester unit include, for example, α-olefins having 4 or less carbon atoms such as ethylene, propylene, 1-butene and isobutene; methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether. And vinyl ethers such as isopropyl vinyl ether and n-butyl vinyl ether.
The content ratio of the comonomer units other than the vinyl ester unit is preferably 1 to 20 mol%, more preferably 4 to 15 mol%, and particularly preferably 6 to 13 mol%. Among these, ethylene-modified PVA containing 4 to 15 mol%, more preferably 6 to 13 mol% of ethylene units is preferable from the viewpoint of improving the physical properties of the sea-island composite fibers.

The viscosity average degree of polymerization of the PVA-based resin is 200 to 500, more preferably 230 to 470, and particularly 250 to 450, so that a stable sea-island structure is formed and the melt spinnability is excellent. It is preferable from the point which shows melt viscosity and the point that the melt | dissolution rate at the time of melt | dissolution is quick. The degree of polymerization is measured according to JIS-K6726. That is, after re-saponifying and purifying the PVA resin, it is obtained from the intrinsic viscosity [η] measured in water at 30 ° C. by the following equation.
Viscosity average degree of polymerization P = ([η] × 103 / 8.29) (1 / 0.62)
The saponification degree of the PVA-based resin is 90 to 99.99 mol%, more preferably 93 to 99.98 mol%, particularly 94 to 99.97 mol%, particularly 96 to 99.96 mol%. It is preferable that it is the range of these. When the saponification degree is in such a range, a PVA resin having excellent water solubility, excellent thermal stability, excellent melt spinnability, and excellent biodegradability can be obtained.

The melting point of the PVA-based resin is 160 to 250 ° C., more preferably 170 to 227 ° C., particularly 175 to 224 ° C., particularly 180 to 220 ° C., in view of mechanical properties and thermal stability. It is preferable from the point which is excellent, and the point which is excellent in melt spinnability.
When the melting point of the PVA-based resin is too high, the melting point and the decomposition temperature are close to each other, so that the melt spinnability tends to be reduced by causing decomposition during melt spinning.
Moreover, when the melting point of the PVA-based resin is too low as compared with the melting point of the water-insoluble thermoplastic resin, it is not preferable because the melt spinnability is lowered.
From such a viewpoint, the melting point of the PVA-based resin is preferably not lower than 60 ° C. or higher, more preferably not lower than 30 ° C. or lower, compared to the melting point of the water-insoluble thermoplastic resin.

As the water-insoluble thermoplastic resin, a resin that can be melt-spun and is a thermoplastic resin that is not dissolved or removed by water, an alkaline aqueous solution, an acidic aqueous solution, or the like.
Specific examples of the water-insoluble thermoplastic resin include the resins described as the resin forming the specific example of the ultrafine single fiber in the specific example of the ultrafine single fiber constituting the nonwoven fabric described above.
The water-insoluble thermoplastic resin may contain various additives. Specific examples of the additive include, for example, a catalyst, an anti-coloring agent, a heat-resistant agent, a flame retardant, a lubricant, an antifouling agent, a fluorescent whitening agent, a matting agent, a coloring agent, a gloss improving agent, an antistatic agent, and an aroma. Agents, deodorants, antibacterial agents, acaricides, inorganic fine particles and the like.

Next, a method for forming a sea-island composite fiber by melt spinning the water-soluble thermoplastic resin and the water-insoluble thermoplastic resin and forming a long fiber web from the obtained sea-island composite fiber will be described in detail. To do.
The long fiber web can be obtained, for example, by combining the water-soluble thermoplastic resin and the water-insoluble thermoplastic resin by melt spinning and then stretching and depositing by a spunbond method. In this way, by forming the web by the spunbond method, a long fiber web made of sea-island type composite fibers with less fiber loss, high fiber density, and good shape stability can be obtained. In addition, a long fiber is a fiber manufactured without passing through a cutting process like manufacturing a short fiber.

In the production of a sea-island type composite fiber, a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin are melt-spun and combined.
The mass ratio of the water-soluble thermoplastic resin to the water-insoluble thermoplastic resin is preferably in the range of 5/95 to 50/50, more preferably 10/90 to 40/60. When the mass ratio of the water-soluble thermoplastic resin and the water-insoluble thermoplastic resin is within such a range, a high-density nonwoven fabric can be obtained and the formability of ultrafine single fibers is excellent.

  A method for forming a long fiber web by a spunbond method after combining a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin by melt spinning will be described in detail below.

First, a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin are melted and kneaded by separate extruders, and molten resin strands are simultaneously discharged from different spinnerets. Then, after the discharged strands are combined with the composite nozzle, the sea-island type composite fibers are formed by discharging from the nozzle holes of the spinning head.
In melt composite spinning, the number of islands in a sea-island type composite fiber is 4 to 4000 islands / fiber, more preferably 10 to 1000 islands / fiber, so that a fiber bundle having a small single fiber fineness and a high fiber density can be obtained. To preferred.

After the sea-island type composite fiber is cooled by a cooling device, it is stretched by a high-speed air current at a speed corresponding to a take-up speed of 1000 to 6000 m / min so as to obtain a desired fineness using a suction device such as an air jet nozzle. The Thereafter, the stretched composite fibers are deposited on a movable collection surface to form a long fiber web. At this time, the long fiber web deposited may be partially crimped as necessary.
A nonwoven fabric having a uniform basis weight of the fiber web in the range of ^{20 to} 500 g / m ² is obtained, and is preferred from the viewpoint of industrial properties.

(2) Web entanglement process Next, the web entanglement process which forms a web entanglement sheet | seat by accumulating and entwining a plurality of the said long fiber webs is demonstrated.
The web entangled sheet is formed by performing an entanglement treatment on the long fiber web using a known nonwoven fabric manufacturing method such as needle punching or high-pressure water flow treatment. Below, the entanglement process by a needle punch is demonstrated in detail as a typical example.

First, a silicone oil agent or a mineral oil agent such as a needle breakage prevention oil agent, an antistatic oil agent, and an entanglement improving oil agent is applied to the long fiber web. In order to reduce unevenness in weight per unit area, two or more fiber webs may be overlapped with a cross wrapper and an oil agent may be applied.
Thereafter, for example, an entanglement process is performed in which the fibers are entangled three-dimensionally by a needle punch. By performing the needle punching process, a web entangled sheet having a high fiber density and hardly causing the fiber to come off can be obtained.
The basis weight of the web entangled sheet is appropriately selected according to the thickness of the target abrasive (hereinafter also referred to as a polishing pad), and specifically, for example, 100 to 1500 g. / M ² is preferable from the viewpoint of excellent handleability.

The conditions such that the delamination force of the web entangled sheet is increased as appropriate for the needle conditions such as the type and amount of the oil agent and the needle shape, needle depth, and number of punches in the needle punch.
The number of barbs is preferably as large as possible without causing needle breakage. Specifically, for example, the number of barbs is selected from 1 to 9 barbs. The needle depth is preferably set so that the barb penetrates to the overlapped web surface, and in a range where the pattern after needle punching does not appear strongly on the web surface.
The number of needle punches is adjusted according to the shape of the needle, the type and amount of oil used, and specifically, 500 to 5000 punches / cm ² is preferable.
In addition, the fiber density can be obtained by performing the entanglement process so that the basis weight after the entanglement process is 1.2 times or more by mass ratio of the basis weight before the entanglement process, and further 1.5 times or more. A high non-woven fabric is obtained, and it is preferable from the viewpoint that the loss of fibers can be reduced. The upper limit is not particularly limited, but is preferably 4 times or less from the viewpoint of avoiding an increase in manufacturing cost due to a decrease in processing speed.

The delamination force of the web entangled sheet is 2 kg / 2.5 cm or more, more preferably 4 kg / 2.5 cm or more, the shape retention is good, the fibers are not easily pulled out, and the fiber density is high. It is preferable from the point by which a nonwoven fabric is obtained.
Note that the delamination force is a measure of the degree of three-dimensional entanglement. If the delamination force is too small, the fiber density of the nonwoven fabric is not sufficiently high. Moreover, although the upper limit of the delamination force of a nonwoven fabric is not specifically limited, From the point of entanglement process efficiency, it is preferable that it is 30 kg / 2.5 cm or less.

  Moreover, in the (2) web entanglement process of this embodiment, in order to adjust the hardness of the non-woven fabric, a plurality of long fiber webs are used as described above within a range not impairing the effects of the present invention. Further, a knitted fabric or a woven fabric (knitted fabric) made of ultrafine fibers is further stacked on the long fiber web entangled body obtained by entanglement, and the entanglement treatment is performed by needle punching treatment and / or high-pressure water flow treatment. Also good. That is, a long fiber web entangled body may be used as a web entangled sheet, but a laminated structure in which a knitted fabric is entangled and integrated with the long fiber web entangled body, for example, a knitted fabric / long fiber web entangled body, a long A laminated structure such as a fiber web entangled body / knitted fabric / long fiber web entangled body may be used as the web entangled sheet.

The ultrafine single fiber which comprises the said knitted fabric is not specifically limited. Specifically, for example, polyester fiber formed from polyethylene terephthalate (PET), polytrimethylene terephthalate, polybutylene terephthalate (PBT), polyester elastomer, etc .; from polyamide 6, polyamide 66, aromatic polyamide, polyamide elastomer, etc. Polyamide fibers to be formed; fibers made of urethane polymers, olefin polymers, acrylonitrile polymers and the like are preferably used.
In these, the fiber formed from PET, PBT, polyamide 6, polyamide 66 etc. is preferable from an industrial point.

Specific examples of the removal component of the sea-island type composite fiber for forming the knitted fabric include polystyrene and its copolymer, polyethylene, PVA resin, copolymer polyester, copolymer polyamide, and the like.
Among these, PVA-based resins are preferably used because they cause large shrinkage when dissolved and removed.

(3) Wet heat shrinkage treatment step Next, a wet heat shrinkage treatment step for increasing the fiber density and the degree of entanglement of the web entangled sheet by shrinking the web entangled sheet with heat and moisture will be described. In this step, the web-entangled sheet containing long fibers is contracted by wet heat, so that the web-entangled sheet is contracted greatly compared to the case where the web-entangled sheet containing short fibers is contracted by wet heat. As a result, the fiber density of the ultrafine single fiber is particularly high.

The wet heat shrinkage treatment is preferably performed by steam heating.
Although it does not specifically limit as steam heating conditions, It is preferable to heat-process for 60 to 600 second by relative humidity 75% or more and also relative humidity 90% or more in the range of 60-130 degreeC of atmospheric temperature. Such heating conditions are preferable because the web-entangled sheet can be shrunk at a high shrinkage rate. In addition, when relative humidity is too low, there exists a tendency for shrinkage | contraction to become inadequate because the water | moisture content which contacted the fiber dries rapidly.

In the wet heat shrinkage treatment, the web entangled sheet is preferably shrunk so that the area shrinkage rate is 35% or more, and further 40% or more. By shrinking at such a high shrinkage rate, a high fiber density can be obtained. The upper limit of the area shrinkage rate is not particularly limited, but is preferably about 80% or less from the viewpoint of shrinkage limit and processing efficiency.
The area shrinkage rate (%) is expressed by the following formula (1):
(Area of sheet surface before shrinking process−Area of sheet surface after shrinking process) / Area of sheet surface before shrinking process × 100 (1) The said area means the average area of the area of the surface of a sheet | seat, and the area of a back surface.

The web entangled sheet thus subjected to the wet heat shrinkage treatment may be further increased in fiber density by heating roll or hot pressing at a temperature equal to or higher than the heat deformation temperature of the sea-island type composite fiber.
In addition, as a change in the basis weight of the web-entangled sheet before and after the wet heat shrinkage treatment, the basis weight after the shrinkage treatment is 1.2 times (mass ratio) or more compared to the basis weight before the shrinkage treatment, It is preferably 1.5 times or more, 4 times or less, and more preferably 3 times or less.

(4) Fiber bundle binding step Before the ultra-fine fiber forming process (5), the web-entangled sheet is subjected to ultrafine fiber treatment, and the purpose of improving the morphological stability of the web-entangled sheet and the porosity of the resulting abrasive material For the purpose of reducing the fiber bundle, the fiber entangled sheet that has been subjected to the shrinkage treatment is impregnated with an aqueous liquid of a polymer elastic body and dried and solidified as necessary, so that the fiber bundle may be bound in advance. Good.

  In this step, the web entangled sheet is filled with the polymer elastic body by impregnating the contracted web entangled sheet with the aqueous liquid of the polymer elastic body and drying and solidifying it. A polymer elastic body can be formed by impregnating a polymer elastic body in the state of an aqueous liquid and drying and solidifying or heat-gelling and solidifying. Therefore, the polymer elastic body filled in this step firmly binds the long-sea sea-island composite fiber.

The aqueous liquid of the polymer elastic body is an aqueous dispersion in which a component forming the polymer elastic body is dispersed in an aqueous medium, or an aqueous solution in which a component forming the polymer elastic body is dissolved in the aqueous medium. The aqueous dispersion includes a suspension dispersion and an emulsion dispersion. In particular, it is more preferable to use an aqueous dispersion from the viewpoint of excellent water resistance.
In addition, the resin contained in the aqueous liquid of the polymer elastic body is as described above as the resin contained in the polymer elastic body.

  The method for producing the aqueous solution or the aqueous dispersion is not particularly limited, and a known method can be used. Specifically, for example, by adding a monomer unit having a hydrophilic group such as a carboxyl group, a sulfonic acid group, or a hydroxyl group to the resin, a method of imparting dispersibility to an aqueous medium to the resin, or a surface activity of the resin The method of emulsifying or suspending by adding an agent is mentioned. Further, such an aqueous polymer elastic body has excellent wettability to water, and thus has excellent characteristics for holding a large amount of abrasive grains.

Specific examples of the surfactant used for the emulsification or suspension include, for example, sodium lauryl sulfate, ammonium lauryl sulfate, sodium polyoxyethylene tridecyl ether acetate, sodium dodecylbenzene sulfonate, sodium alkyldiphenyl ether disulfonate, dioctyl sulfosuccinate. Anionic surfactants such as sodium oxide; nonions such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene-polyoxypropylene block copolymer Surfactants and the like. Moreover, you may use what is called reactive surfactant which has reactivity. Moreover, heat-sensitive gelling property can also be provided to resin by selecting suitably the cloud point of surfactant.
The dispersion average particle size of the aqueous resin dispersion is preferably 0.01 to 1 μm, and more preferably 0.03 to 0.5 μm.

In this step, in order to form the polymer elastic body, an aqueous solution of the polymer elastic body is used instead of the organic solvent solution of the polymer elastic body generally used conventionally. Thus, by using the aqueous liquid of the polymer elastic body, it is possible to impregnate the resin liquid containing the resin at a higher concentration. And thereby, the porosity of the obtained abrasive can be sufficiently reduced.
The solid content concentration of the aqueous liquid of the polymer elastic body is preferably 15% by mass or more, and more preferably 25% by mass or more from the viewpoint that the porosity can be sufficiently reduced.

Examples of the method of impregnating the web entangled sheet with the aqueous polymer elastic liquid include a method using a knife coater, a bar coater, or a roll coater, or a dipping method.
The polymer elastic body can be solidified by drying the web entangled sheet impregnated with the aqueous liquid of the polymer elastic body. As a drying method, the method of heat-processing in a 50-200 degreeC drying apparatus, the method of heat-processing in a dryer after infrared heating, etc. are mentioned.

  When the web entangled sheet is impregnated with an aqueous liquid of a polymer elastic body and then dried, the aqueous liquid migrates to the surface layer of the web entangled sheet, thereby obtaining a uniform filling state. It may not be possible. In such cases, adjust the particle size of the resin in the aqueous liquid; adjust the type and amount of the ionic group of the resin in the aqueous liquid, or change the pH of the aqueous liquid to stabilize it. Adjusting the property; associative heat-sensitive gelling agent such as monovalent or divalent alkali metal salt or alkaline earth metal salt, nonionic emulsifier, associative water-soluble thickener, water-soluble silicone compound, or Migration can be suppressed by reducing the water dispersion stability at about 40 to 100 ° C. by using a water-soluble polyurethane compound in combination. In addition, you may make it migrate so that the aqueous liquid of a polymeric elastic body may be unevenly distributed on the surface as needed.

(5) Ultrafine fiber formation process Next, the ultrafine fiber formation process which is a process of forming ultrafine single fiber by melt | dissolving a water-soluble thermoplastic resin in hot water is demonstrated.
This step is a step of forming ultrafine single fibers by removing the water-soluble thermoplastic resin. At this time, voids are formed in the portion of the web entangled sheet where the water-soluble thermoplastic resin is dissolved and extracted. Then, in the subsequent polymer elastic body filling step (6), the ultrafine single fibers are focused by filling the voids with the polymer elastic body.

The ultrafine fiber treatment is a web entangled sheet obtained through the wet heat shrinkage treatment step (3) or a composite of the web entangled sheet obtained through the fiber bundle binding step (4) and the polymer elastic body. In this process, the water-soluble thermoplastic resin is dissolved or removed by hot water heat treatment with water, an alkaline aqueous solution, an acidic aqueous solution or the like.
As a specific example of the hot water heat treatment conditions, for example, as a first stage, after being immersed in hot water at 65 to 90 ° C. for 5 to 300 seconds, further as a second stage, hot water at 85 to 100 ° C. It is preferable to perform the treatment for 100 to 600 seconds. Moreover, in order to improve dissolution efficiency, you may perform the nip process by a roll, a high pressure water flow process, an ultrasonic process, a shower process, a stirring process, a stagnation process, etc. as needed.

  In this step, the ultrafine fiber is greatly crimped when the ultrafine single fiber is formed by dissolving the water-soluble thermoplastic resin from the sea-island type composite fiber. Since the fiber density becomes dense by this crimping, a high-density nonwoven fabric is obtained.

(6) Polymer elastic body filling step Next, by filling a polymer elastic body into an ultrafine fiber bundle formed of ultrafine single fibers, the ultrafine single fibers are focused and the fiber bundles are bound together. The process will be described.
In the ultrafine fiber forming step (5), the sea-island type composite fiber is subjected to ultrafine fiber treatment, whereby the water-soluble thermoplastic resin is removed and voids are formed inside the ultrafine fiber bundle. In this step, by filling the voids with a polymer elastic body, the ultrafine fibers can be focused and the porosity of the abrasive can be reduced. When the ultrafine single fibers form a fiber bundle, the ultrafine single fibers are more easily focused and constrained because they are easily impregnated with an aqueous liquid of a polymer elastic body due to capillary action.

The aqueous polymer liquid used in this step may be the same as the aqueous polymer elastic liquid described in the fiber bundle binding step (4).
A method similar to the method used in the fiber bundle binding step (4) can be applied to the method of filling the polymer elastic body into the ultrafine fiber bundle formed from the ultrafine single fibers in this step. In this way, an abrasive is formed.
In the present invention, as a method for applying the polymer elastic body, at least one step of the fiber bundle binding step (4) and the polymer elastic body filling step (6) may be performed, and both steps may be performed. Are preferable for the reasons described above.

[Post-processing of abrasives]
The obtained abrasive may be subjected to post-processing treatment such as molding treatment, flattening treatment, raising treatment, laminating treatment, and surface treatment as necessary.

The forming process and the flattening process are processes in which the obtained abrasive is hot-press formed to a predetermined thickness by grinding or cut into a predetermined outer shape. The abrasive is preferably ground to a thickness of about 0.5 to 3 mm.
The raising treatment is a treatment for separating the converged ultrafine single fibers by applying mechanical frictional force or polishing force to the surface of the abrasive with sandpaper, needle cloth, diamond or the like. By such raising treatment, the fiber bundle existing in the surface layer of the abrasive is fibrillated, and a large number of ultrafine single fibers are formed on the surface.

The laminating process is a process of adjusting rigidity by laminating the obtained abrasive on a base material. For example, by laminating an abrasive with an elastic sheet having low hardness, the global flatness of the surface to be polished (the flatness of the entire non-polishing substrate) can be further improved. The adhesion at the time of lamination may be fusion adhesion or adhesion via an adhesive or a pressure-sensitive adhesive.
Specific examples of the substrate include, for example, an elastic sponge body made of polyurethane or the like; a nonwoven fabric impregnated with polyurethane (for example, trade name Suba400 manufactured by Nita Haas Co.); natural rubber, nitrile rubber, polybutadiene rubber, silicone Examples thereof include elastic resin films composed of rubbers such as rubber, thermoplastic elastomers such as polyester-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and fluorine-based thermoplastic elastomers; foamed plastics; sheet-like substrates such as knitted fabrics and woven fabrics.

  The surface treatment is a treatment for forming grooves, holes such as lattices, concentric circles, and spirals on the surface of the abrasive material in order to adjust the retention and discharge of the abrasive slurry.

2. Slurry containing abrasive grains (abrasive slurry)
The polishing method of this embodiment uses a slurry containing abrasive grains.
The abrasive slurry of this embodiment is a slurry in which abrasive particles are dispersed in a liquid medium such as water or oil. Moreover, an abrasive grain slurry may contain components, such as a base, an acid, and surfactant, as needed. Further, in the polishing method of this embodiment, when performing CMP, lubricating oil, coolant, and the like may be supplied together with the polishing slurry as necessary.
When the content of the abrasive grains in the abrasive slurry is too small, the polishing rate tends to decrease. On the other hand, when the content is too large, the dispersion stability of the abrasive grains tends to decrease and the cost increases. The content is preferably 001% by mass to 25% by mass, more preferably 0.005% by mass to 15% by mass, and still more preferably 0.1% by mass to 13% by mass.

The abrasive grains of this embodiment are preferably inorganic particles such as silica, aluminum oxide, cerium oxide, zirconium oxide, silicon carbide and diamond.
The average particle diameter of the abrasive grains is 0.01 μm to 20 μm in order to take advantage of the characteristics of the abrasive of the present embodiment. When the average particle size is less than 0.01 μm, the polishing rate decreases because the particle size is too small to be held on the surface of the abrasive used in the present invention. On the other hand, if it exceeds 20 μm, the polishing rate is improved at the beginning of polishing, but the fibers on the surface of the abrasive are easily cut, and polishing scratches are generated. The average grain size of the abrasive grains is preferably 0.05 μm to 15 μm, and more preferably 0.1 μm to 10 μm.

3. Compound Semiconductor Wafer The polishing method of the present embodiment is preferably used for lapping a compound semiconductor wafer substrate or the like.
Specific examples of compound semiconductor wafers (including compound semiconductor devices) include, for example, GaAs compound semiconductor wafers or SiC compound semiconductor wafers.

  Hereinafter, the present invention will be specifically described by way of examples. In addition, this invention is not limited at all by the Example.

[Example 1]
Water-soluble thermoplastic polyvinyl alcohol resin (hereinafter referred to as PVA resin), isophthalic acid-modified polyethylene terephthalate (hereinafter referred to as modified PET: T _g 77 ° C., water absorption 1% by mass, A sea-island type composite fiber was formed by discharging it from the melt composite spinning die at a ratio of 25% (mass ratio). The melt compound spinning die had 25 islands / fiber and a die temperature of 260 ° C. Then, by adjusting the ejector pressure to a spinning speed of 4000 m / min and collecting long fibers having an average fineness of 2.0 dtex on the net, a spunbond sheet (long fiber web) having a basis weight of 30 g / m ² is collected. )was gotten.
Sixteen spunbond sheets obtained were overlapped by cross-wrapping to produce an overlap web having a total basis weight of 480 g / m ² . And the needle | hook breaking prevention oil agent was sprayed on the obtained overlapping web. Next, using the needle needle of 42 needle count with 1 barb and the needle needle of 42 needle count with 6 barbs, the overlap web is needle-punched at 1800 punch / cm ² and entangled By doing so, a web entangled sheet was obtained. The basis weight of the obtained web entangled sheet was 740 g / m ² , and the delamination force was 10.0 kg / 2.5 cm. Moreover, the area shrinkage rate by the needle punch process was 35%.
Next, the obtained web-entangled sheet was steam-treated for 90 seconds under the conditions of 70 ° C. and 95% RH. The area shrinkage rate at this time was 50%. And after drying in 140 degreeC oven, the web entanglement sheet | seat of the amount per unit area of 1480 g / m < ² >, the apparent density of 0.78 g / cm < ³ >, and the thickness of 1.90 mm was obtained by heat-pressing at 140 degreeC. . At this time, the thickness of the web entangled sheet after hot pressing was 0.70 times the thickness before hot pressing.
Next, polyurethane resin A (polycarbonate-based polyol, polyalkylene glycol having 2 to 3 carbon atoms, and polyalkylene glycol having 4 carbon atoms, which is a first resin for forming a polymer elastic body, 6: This is a non-yellowing type polyurethane resin comprising a polycarbonate / polyether (6/4) polyol mixed at 0.5: 3.5 (molar ratio) as a polyol component, and the water absorption of polyurethane resin A is 5% by mass, 150%. The storage elastic modulus [E (150 ° C., dry)] at 60 ° C. is 60 MPa.) An aqueous dispersion (solid content concentration of 25% by mass) of the aqueous dispersion is attached to the web-entangled sheet after hot pressing. Impregnates the web entangled sheet to 12% with respect to the mass of the web entangled sheet, and dries and solidifies the web entangled sheet impregnated with the aqueous dispersion in an atmosphere of 90 ° C. and 50% RH. And management, was further dried at 140 ° C.. The sea-island type composite fiber constituting the obtained web entangled sheet was previously bound with polyurethane resin A.
Next, the PVA resin is dissolved and removed by immersing the web entangled sheet with the polyurethane resin A bound in 95 ° C. hot water for 10 minutes while performing high-pressure water flow treatment and nip treatment, and further, by drying, A nonwoven fabric in which the ultrafine fiber bundle was bound by the polyurethane resin A was obtained.
Then, in order to further fill the nonwoven fabric with a polymer elastic body, the second resin, polyurethane resin B (polycarbonate-based polyol and C2-C3 polyalkylene glycol, 99.8: 0.2 (molar ratio) ) Is used as a polyol component, and 5 parts by mass of a carbodiimide-based crosslinking agent is added to 100 parts by mass of a non-yellowing polyurethane resin containing 1.5% by mass of a carboxyl group-containing monomer, followed by heat treatment to form a crosslinked structure. Polyurethane resin B. Water dispersion of polyurethane resin B is 2% by mass, storage elastic modulus at 150 ° C. [E (150 ° C., dry)] is 40 MPa). The nonwoven fabric was impregnated. And it solidified in 90 degreeC and 50% RH atmosphere, and also dried at 150 degreeC. The solid content adhesion amount of the aqueous dispersion was 12% by mass relative to the mass of the abrasive. The obtained abrasive has a basis weight of 1190 g / m ² , an apparent density of 0.85 g / cm ³ , a thickness of 1.4 mm, an abrasive filling rate of 60%, and a mass ratio of the nonwoven fabric and polyurethane elastic body (polymer elastic body). Was 85/15. The obtained abrasive was polished and evaluated by a polishing method described later. The results are shown in Table 1.

[Example 2]
In the production of the sea-island type composite fiber, the ratio of the PVA resin to the modified PET is set to 15:85 instead of 25:75, the aqueous dispersion of the first resin (polyurethane resin A), and the second An abrasive was obtained in the same manner as in Example 1 except that the solid concentration of the aqueous dispersion of the resin (polyurethane resin B) was 50% by mass. The obtained abrasive had a basis weight of 1900 g / m ² , an apparent density of 1.12 g / cm ³ , a thickness of 1.7 m, an abrasive filling rate of 90%, and a mass ratio of the nonwoven fabric to the polyurethane elastic body was 58/42. It was. The obtained abrasive was evaluated by the evaluation method described later. The results are shown in Table 1.

[Example 3]
An abrasive was produced in the same manner as in Example 1 except that the aqueous dispersion solid content concentration of the second resin (polyurethane resin B) was changed to 10%. The obtained abrasive had a basis weight of 1120 g / m ² , an apparent density of 0.80 g / cm ³ , a thickness of 1.4 m, an abrasive filling rate of 62%, and a mass ratio of the nonwoven fabric to the polyurethane elastic body was 78/22. It was. The obtained abrasive was evaluated by the evaluation method described later. The results are shown in Table 1.

[Example 4]
In order to form a sea-island type composite fiber, the same procedure as in Example 2 was used, except that a melt composite spinning base with 5 islands / fiber was used instead of a melt composite spinning base with 25 islands / fiber. To obtain an abrasive. The obtained abrasive had a basis weight of 1580 g / m ² , an apparent density of 0.88 g / cm ³ , a thickness of 1.8 m, and a fiber density on the surface of 700 fibers / mm ^{2 as} observed by SEM. The obtained nonwoven fabric was evaluated by an evaluation method described later. The results are shown in Table 1.

[Comparative Example 1]
A sea-island type composite fiber was formed by discharging the PVA resin and the modified PET from the melt composite spinning die at a ratio of 40:60 (mass ratio). The obtained sea-island type composite fiber was drawn and crimped, and then cut to obtain a short fiber having a fineness of 6 dtex and a fiber length of 51 mm. A short fiber web having a basis weight of 30 g / m ² was obtained by carding and cross-wrapping the obtained short fibers.
An abrasive was prepared and evaluated in the same manner as in Example 2 except that the obtained short fiber web was used instead of the spunbond sheet (long fiber web). In addition, the area shrinkage rate when the web entangled sheet obtained from the short fiber web was steam-treated was 30%. The obtained abrasive was evaluated by the evaluation method described later. The results are shown in Table 1.

[Comparative Example 2]
Instead of using the spunbond sheet made of the sea-island type composite fiber of Example 1, a spunbond sheet with a basis weight of 30 g / m ² obtained by collecting PET long single fibers having an average fineness of 0.2 dtex on a net was obtained. An abrasive was obtained in the same manner as in Example 1 except that the step of dissolving and removing the PVA-based resin was omitted. From the cross-sectional observation by SEM, the ultrafine single fiber of the obtained abrasive did not form a fiber bundle. The obtained abrasive was evaluated by the evaluation method described later. The results are shown in Table 1.

[Comparative Example 3]
A hot-pressed web entangled sheet produced in the same manner as in Example 1 was impregnated with an aqueous dispersion of polyurethane resin A (solid content concentration 40% by mass). At this time, the solid content adhesion amount of the aqueous dispersion was 30% by mass with respect to the mass of the web entangled sheet. The web entangled sheet impregnated with the aqueous dispersion was coagulated in an atmosphere of 90 ° C. and 50% RH, and further dried at 140 ° C. And the buffing process was performed and the surface and the back surface were planarized. Next, the web entangled sheet filled with the polyurethane resin A was immersed in hot water at 95 ° C. for 10 minutes to dissolve and remove the PVA resin, and further dried to obtain an abrasive. The obtained abrasive was evaluated by the evaluation method described later. The results are shown in Table 1.

[Comparative Example 4]
Instead of using the spunbond sheet made of the sea-island type composite fiber of Example 1, a spunbond sheet obtained by collecting PET continuous fibers having an average fineness of 2 dtex on the net is used to perform a PVA resin dissolution and removal step. An abrasive was obtained in the same manner as in Example 1 except that it was omitted. The obtained abrasive was evaluated by the evaluation method described later. The results are shown in Table 1.

[Comparative Example 5]
An abrasive was prepared in the same manner as in Example 1 except that methyl methacrylate monomer was immersed in a sheet and polymerized in nitrogen instead of filling with polyurethane resin B after ultrafine fiber formation. The obtained abrasive was evaluated by the evaluation method described later. The results are shown in Table 1.

[Comparative Example 6]
Evaluation was performed using a polishing cloth (HYPREZ: 415) manufactured by Nippon Engis Co., Ltd., in which one side of the rayon woven fabric was subjected to adhesive processing. The results are shown in Table 1.

[Comparative Example 7]
Evaluation was made by attaching SUBA800 manufactured by Rohm & Haas Co. to the polishing surface plate. The results are shown in Table 1.

The obtained abrasive was evaluated by the following evaluation method.
[Evaluation methods]
(1) Average cross-sectional area of ultrafine single fiber The obtained abrasive was cut in the thickness direction using a cutter blade to form a cut surface in the thickness direction. The obtained cut surface was stained with osmium oxide. And the said cut surface was observed with the magnification of 500-1000 times of the scanning electron microscope (SEM), and the image was image | photographed. And the cross-sectional area of the ultrafine fiber which exists in a cut surface was calculated | required from the obtained image. A value obtained by averaging 100 randomly selected cross-sectional areas was defined as an average cross-sectional area.
(2) Apparent density of abrasive The apparent density of the obtained abrasive was measured according to JIS K7112.
(3) D hardness measurement The JIS-D hardness at 23 ° C of the abrasive was measured according to JIS K7311.
(4) Taber Abrasion Loss Abrasion loss was measured for the abrasive material in accordance with JIS L1096 8.17.3C (Taber format) with a wear wheel of H-22, a load of 500 g and 1000 times.
In the case of the weight loss of wear exceeding 150 mg / 1000 times, it was determined to be “x”, and less than that was evaluated as “good”.
(5) Polishing performance evaluation After sticking an adhesive tape on the back surface of the circular abrasive, it was mounted as a primary polishing on a CMP polishing apparatus ("BC-15" manufactured by MG Corporation). Then, 50 cc of water was sprayed with a quantitative spray, and the abrasive surface was wetted with moisture. Subsequently, the average particle diameter was calculated | required by the cumulant method from the autocorrelation function calculated | required by the average particle diameter 1.0micrometer: Photon correlation method of the polycrystalline diamond abrasive water dispersion (Komet 1-W2-PC-STD abrasive grain). ) 1 cc / min. The SiC wafer (Tank Blue 2 inch, thickness 0.4 mm) was mounted on the polishing head and lapped for 15 minutes. The load at this time was 0.15 (kgf / cm ² ), the platen rotation speed was 40 (rpm), and the wafer rotation speed was 39 (rpm). The polishing rate was changed to the polishing rate by measuring the weight before and after polishing and reducing the weight.
When the polishing rate was less than 30 mg / hr, the polishing efficiency was remarkably lowered, so that the determination was x.
As for the polishing scratches, the surface of the wafer was observed with a digital microscope manufactured by Scalar with a magnification set to 200 times. The scratches were undamaged, and those with slight scratches (5 or less on the wafer) could be confirmed. Those in which many scratches could be confirmed were evaluated as x (six or more on the wafer).
Next, except that abrasive grains having an average particle size of 0.1 μm are used as final polishing, the polishing rate is measured by the same method. When the polishing rate is less than 10 mg / hr, the polishing efficiency is remarkably lowered, and thus the determination is x. If it was more than that, it was judged as “good”.
The average particle size of the abrasive grains was measured with ELS-Z manufactured by Otsuka Electronics.

Claims (6)

A polishing method for polishing a compound semiconductor wafer using an abrasive and a slurry containing abrasive grains,
The abrasive has an average cross-sectional area of the nonwoven fabric and the elastic polymer consisting of ultrafine single fibers is 0.01 [mu] m ² 30 .mu.m ^2, the weight ratio of the nonwoven fabric / elastic polymer is 90 / 10-55 / 45 wherein in the range, and has a JIS hardness of apparent density and 45D~75D of ^{0.70g / cm 3 ~1.2g / cm 3} ,
The polishing method, wherein the abrasive has an average particle size of 0.01 μm to 20 μm.   The polishing method according to claim 1, wherein the polymer elastic body includes a polyurethane-based resin.   The polishing method according to claim 2, wherein the polyurethane resin is a water dispersible polyurethane resin.   The said ultra fine single fiber contains at least 1 fiber chosen from the group which consists of an aromatic polyester fiber, an aliphatic polyester fiber, a polyamide fiber, a polyolefin fiber, a vinylon fiber, and an acrylic fiber, The any one of Claims 1-3. Polishing method.   The polishing method according to claim 1, wherein the compound semiconductor wafer is a GaAs compound semiconductor wafer or a SiC compound semiconductor wafer.   The manufacturing method of a compound semiconductor wafer including the process of grind | polishing a compound semiconductor wafer with the grinding | polishing method of any one of Claims 1-5.