JP2010058170A - Polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad hardly causing a scratch and excellent in planarization performance and in polishing stability. <P>SOLUTION: The polishing pad is formed of ultrafine fibers whose average fineness is 0.01 to 0.8 dtex and a polymeric elastomer, having a bending elastic modulus of 150 to 800 MPa and a water absorption height of at least 10 mm as measured with water after 60 minutes in a Byreck-method water absorption height test conforming to JIS L 1907-1994. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention is a polishing pad, more specifically, various devices such as various devices that are flattened or mirrored, various substrates, such as semiconductor substrates, semiconductor devices, compound semiconductor devices, compound semiconductor substrates, compound semiconductor products, LED substrates, The present invention relates to a polishing pad for polishing LED products, silicon wafers, hard disk substrates, glass substrates, glass products, metal substrates, metal products, plastic substrates, plastic products, ceramic substrates, ceramic products, and the like, and a method for manufacturing the same.

  In recent years, with high integration of integrated circuits and multilayer wiring, semiconductor wafers on which integrated circuits are formed are required to have high precision flatness.

  As a polishing method for polishing a semiconductor wafer, chemical mechanical polishing (CMP) is known. CMP is a method of polishing a surface of a substrate to be polished with a polishing pad while dropping slurry of abrasive grains.

  The following Patent Documents 1 to 4 disclose a polishing pad used for CMP, which is made by foam-molding a two-component curable polyurethane and made of a polymer foam having a closed cell structure. Such a polishing pad is preferably used for polishing a semiconductor wafer that requires high-precision flatness because it has higher rigidity than a non-woven fabric type polishing pad described later.

  A polishing pad made of a polymer foam having a closed cell structure is produced, for example, by casting and molding a two-component curable polyurethane. Since such a polishing pad has a relatively high rigidity, a load is easily applied selectively to the convex portion of the substrate to be polished during polishing, and as a result, the polishing rate (polishing rate) is relatively high. Become. However, when agglomerated abrasive grains are present on the polished surface, a load is selectively applied to the agglomerated abrasive grains, so that the polished surface is easily scratched. In particular, as described in Non-Patent Document 1, scratches and interfacial delamination occur particularly when polishing a substrate having a copper wiring that is easily scratched or a low dielectric constant material having weak interface adhesion. It becomes easy to do. In cast foam molding, since it is difficult to uniformly foam a polymer elastic body, the flatness of the substrate to be polished and the polishing rate at the time of polishing tend to vary. Furthermore, in the polishing pad having independent holes, abrasive grains and polishing debris are clogged in the voids originating from the independent holes. As a result, when used for a long time, the polishing rate decreases as polishing progresses (this characteristic is also referred to as polishing stability).

  On the other hand, as another type of polishing pad, Patent Documents 5 to 14 disclose a nonwoven fabric type polishing pad obtained by impregnating a polyurethane resin with a nonwoven fabric and wet coagulating it. Nonwoven polishing pads are excellent in flexibility. Therefore, when there are aggregated abrasive grains on the polishing surface of the substrate to be polished, the polishing pad is deformed to suppress a load from being selectively applied to the aggregated abrasive grains. However, the non-woven polishing pad tends to change its polishing characteristics with time, and has a problem that it is difficult to use for precise planarization. In addition, since the polishing pad is too flexible and deforms following the surface shape of the substrate to be polished, high flattening performance (characteristic for flattening the substrate to be polished) is difficult to obtain, and the fineness is 2 to 2. Since it is as large as 10 dtex, there is a problem that local stress concentration cannot be avoided.

  In such a nonwoven fabric type polishing pad, 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 15 to 18). Specifically, for example, Patent Document 15 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 entangled 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 described in Patent Documents 15 to 18, since the nonwoven fabric obtained by needle punching the ultrafine fibers having a 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. For this reason, deformation is performed following the surface shape, so that high planarization performance cannot be sufficiently obtained.
Moreover, in such a nonwoven fabric type polishing pad, details of the polymer elastic body are not described in any literature, and there is little description about stability over time.
JP 2000-178374 A JP 2000-248034 A JP 2001-89548 A Japanese Patent Laid-Open No. 11-322878 JP 2002-9026 A JP-A-11-99479 Japanese Patent Laying-Open No. 2005-212055 JP-A-3-234475 JP-A-10-128674 JP 2004-311731 A Japanese Patent Laid-Open No. 10-225864 JP-T-2005-518286 JP 2003-201676 A JP 2005-334997 A JP 2007-54910 A JP 2003-170347 A JP 2004-130395 A JP 2002-172555 A Masahiro Kusunoki et al., “CMP Science”, Science Forum, Inc., August 20, 1997, p.113-119

As described above, a substrate made of ultrafine fibers generally has a characteristic that it has a large surface area and low flexural elasticity. Therefore, a polishing pad obtained by impregnating a conventionally known non-woven fabric made of ultrafine fibers with a polymer elastic body has a large contact area with the substrate to be polished and performs soft polishing. However, only those with low rigidity were obtained, and there were problems in planarization characteristics and polishing stability over time.
In addition, the nonwoven fabric has been known for the past because the voids account for more than half of the apparent volume, although the voids serve as slurry reservoirs and the abrasive slurry slurry has high liquid retention properties, which makes it easy to increase the polishing rate. A polishing pad obtained by impregnating a non-woven fabric with a polymer elastic body can perform efficient polishing, but has a problem of low rigidity and flatness and polishing stability over time. An object of the present invention is to provide a polishing pad that overcomes the above-described problems, hardly generates scratches, and has excellent planarization performance and polishing efficiency.

  The present inventors converge the ultrafine fibers and make them exist like a single thick fiber, thereby increasing the flexural modulus and improving the flattening performance, and further, the capillary phenomenon of the ultrafine fibers. It is found that by using a pad having a high water absorption height, it is possible to improve the slurry retention during polishing and to improve the polishing efficiency and the polishing stability over time while reducing scratches. The present invention has been reached.

That is, the present invention is formed of an ultrafine fiber entangled body made of ultrafine fibers having an average fineness of 0.01 to 0.8 dtex and a polymer elastic body, has a flexural modulus of 150 to 800 MPa, and is JIS L1907-1994. The polishing pad is characterized in that the water absorption height after 60 minutes is 10 mm or more in the birec method water absorption height test based on the above.
The ultrafine fiber entangled body is composed of an ultrafine fiber bundle in which 5 to 70 ultrafine fibers having an average fineness of 0.01 to 0.8 dtex or less are converged, and the polymer elastic body is disposed inside the ultrafine fiber bundle. Preferably, the polymer elastic body contains an 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. It is preferable that the aqueous polyurethane mainly comprises an aqueous polyurethane having an average particle size of 0.01 to 0.2 μm. And it is preferable that the storage elastic modulus in the said polymer elastic body in 23 degreeC and 50 degreeC is the range of 90-900 MPa.
Further, the present invention provides a polishing pad for a semiconductor wafer, characterized in that when the surface of the polishing pad of the present invention is conditioned, the amount of wear loss in the thickness direction of the polishing pad surface is conditioned at 0.3 μm / min or less. This is a conditioning method.

  The polishing pad of the present invention hardly generates scratches and is excellent in flattening performance and polishing stability.

Hereinafter, the configuration of the polishing pad of the present invention, the manufacturing method thereof, and the method of using the same will be described in detail based on embodiments of the present invention. In addition, this invention is not limited at all by embodiment described below.
The ultrafine fiber entangled body is formed from ultrafine fibers having an average fineness of 0.01 to 0.8 dtex, and preferably in the range of 0.05 to 0.5 dtex. When the average fineness of the ultrafine fibers is less than 0.01 dtex, the ultrafine fiber bundle is not sufficiently separated, and as a result, the holding power of the abrasive slurry is lowered, and the polishing efficiency and the polishing uniformity are lowered. On the other hand, when the average fineness of the ultrafine fibers exceeds 0.8 dtex, the surface of the polishing pad becomes too rough, the polishing rate decreases, and the stress caused by the polishing by the fibers increases and scratches occur. It becomes easy.
The ultrafine fiber bundle is preferably composed of 5 to 70 bundled ultrafine fibers, and more preferably 10 to 50. When the number of ultrafine fibers converging exceeds 70, the ultrafine fibers are not sufficiently separated, and as a result, the holding power of the abrasive slurry is lowered. On the other hand, when the number of the ultrafine fiber bundles is less than 5, the fineness is substantially increased or the fiber density on the surface tends to be lowered, and the surface of the polishing pad becomes too rough, resulting in a decrease in the polishing rate. In addition, the stress caused by the polishing with the fibers increases, and scratches are likely to occur. Furthermore, the capillary action is reduced and the slurry retention is reduced. Moreover, in order to enhance the capillary phenomenon of ultrafine fibers, it is necessary to use ultrafine fibers having a fiber bundle.

  Specific examples of the ultrafine fibers constituting the polishing pad of the present invention 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 fiber formed from polyamide 10, polyamide 11, polyamide 12, polyamide 6-12, etc .; polypropylene, polyethylene, polybutene, polymer From polyolefin fibers such as rupentene and chlorine-based polyolefins; modified polyvinyl alcohol fibers formed from modified polyvinyl alcohol containing 25 to 70 mol% of ethylene units; and elastomers such as polyurethane-based elastomers, polyamide-based elastomers, and polyester-based elastomers The elastomer fiber etc. which are formed are mentioned. These may be used alone or in combination of two or more.

Among the ultrafine fibers, glass transition temperature (T _g) 50 ° C. or more, further comprising at 60 ° C. or higher, the fibers water absorption of two mass% or less of the thermoplastic resin.
When the glass transition temperature of the thermoplastic resin is within such a range, higher rigidity can be maintained, so that the flattening performance is further improved. Thus, a polishing pad excellent in polishing stability and polishing uniformity can be obtained. The upper limit of the glass transition temperature is not particularly limited, but is preferably 300 ° C. or lower, and more preferably 150 ° C. or lower for industrial production.
Further, when the water absorption rate of the thermoplastic resin is 2% by mass or less, the polishing pad does not absorb the abrasive slurry excessively even during polishing, so that a decrease in rigidity over time is further suppressed. The In such a case, it is possible to obtain a polishing pad that suppresses a decrease in flattening performance with time and is difficult to change in polishing rate and polishing uniformity. Specific examples of the thermoplastic resin 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), sulfoisophthalate. Acid-modified polyethylene terephthalate (T _g 67-77 ° C., water absorption 1-3% by mass), polybutylene naphthalate (T _g 85 ° C., water absorption 1% by mass), polyethylene naphthalate (T _g 124 ° C., water absorption 1) wt%) aromatic polyester fibers formed from such; terephthalic acid and nonanediol and methyl octanediol copolyamide (T _g 125~140 ℃, water absorption 1-3 wt%) semiaromatic formed from such Examples thereof include polyamide-based fibers. In particular, modified PET, such as PET and isophthalic acid-modified PET, is a dense and high-density fiber because it is crimped greatly in a wet heat treatment process for forming ultrafine fibers from a web-entangled sheet composed of sea-island type composite fibers described later. It is also preferable from the viewpoints that an entangled body can be formed, that the rigidity of the polishing sheet can be easily increased, and that a change with time due to moisture hardly occurs during polishing.

  It is important that the polishing pad of the present invention has a flexural modulus of 150 to 800 MPa. When the flexural modulus is less than 150 MPa, the rigidity of the polishing pad decreases as polishing progresses. As a result, the polishing rate and the flatness of the substrate to be polished tend to decrease. Further, when the bending elastic modulus of the polishing pad exceeds 800 MPa, the rigidity during polishing is too high, and scratches are likely to occur, and the followability to the object to be polished tends to be poor, and polishing spots tend to occur. There is. In order to make a bending elastic modulus into the said range, it can achieve by employ | adopting the below-mentioned method.

  Further, the polishing pad of the present invention has a water absorption height of 60 mm or more after 60 minutes in the birec method water absorption height test in accordance with JIS L1907-1994. This is important because the liquidity and wettability are good, so that a high polishing rate can be obtained, and the polishing uniformity and polishing stability are easily improved. Moreover, since it becomes favorable wettability from the start of grinding | polishing that water absorption height is 10 mm or more, it becomes the tendency for break-in grinding | polishing to be shortened. Furthermore, in recent years, even in an electropolishing method in which development is advanced and polishing is performed by the electrochemical action of the electrolyte solution, the water absorption height is 10 mm or more, so that the electrolyte solution is uniformly retained throughout the pad. This is effective because it tends to perform uniform polishing. And it is preferable that it is 20 mm or more. The upper limit is not particularly set, but is preferably 500 mm or less from the viewpoint that the amount of slurry used can be reduced.

  And in order to make the water absorption height of the water 60 minutes after in a birec method water absorption height test into 10 mm or more, it is preferable that a polishing pad has a communicating hole. Furthermore, by having a communication hole inside the polishing pad of the present invention, the retention of the slurry is further improved. With only the closed cell structure employed in the conventional polishing pad, it is difficult to retain the slurry other than the independent holes existing on the surface, and the liquid retaining property of the pad slurry tends to be insufficient. Here, the communication hole means a hole penetrating the front and back surfaces of the polishing pad.

Since the water absorption height in the communication hole structure correlates with the gap of the polishing pad, the water absorption height after 60 minutes in the Bayrec method water absorption height test can also be adjusted by adjusting the ratio of the void in the polishing pad. Can be adjusted. For example, the polishing pad has voids in a range where the volume ratio excluding voids (hereinafter also referred to as polishing pad filling rate) is in the range of 40 to 95%, that is, in the range in which the porosity is 5 to 60%. It is preferable. The porosity can be appropriately adjusted depending on the fiber entanglement density and the filling amount of the polymer elastic body. In addition, as described above, it is preferable that a part of the gap form a communication hole that communicates with the inside of the polishing pad.
The presence of the communication hole can be confirmed by the water dripped onto the surface of the polishing pad being exposed to the back surface of the polishing pad through the communication hole of the polishing pad.

  In such a birec method water absorption height test based on JIS L1907-1994, in order to increase the water absorption height after 60 minutes to 10 mm or more, ultrafine fibers are present at a high density. The molecular elastic body contains 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, and further has a structure having a communicating hole inside the polishing pad It is possible to adjust preferably.

Apparent density of the polishing pad of the present invention, it slurry retainability is good, and since the rigidity is high, 0.5 to 1.0 g / cm ^3, further, the 0.6~0.9g / cm ³ A range is preferable. In the case of 1.0 / cm ³ or more, it is difficult to make the water absorption height after 60 minutes in the Bayrec method water absorption height test 10 mm or more.

  The polymer elastic body filled in the ultrafine fiber entangled body made of ultrafine fibers having an average fineness of 0.001 to 0.8 dtex of the present invention has a storage elastic modulus at 23 ° C. and 50 ° C. in the range of 90 to 900 MPa. It is preferable that the bending elasticity of the polishing pad is easily adjusted within the range of the present invention. By setting the storage elastic modulus in the range of 23 ° C. and 50 ° C. to 90 MPa or more, the pad rigidity in polishing becomes sufficient, and the flatness is improved. Further, the polymer elastic body is less likely to swell due to the slurry during polishing, and the temporal stability tends to be improved. By setting the storage elastic modulus at 23 ° C. and 50 ° C. to 900 MPa or less, it becomes difficult for the polymer elastic body to fall off during polishing, and scratches are hardly generated. In addition, the convergence force of the ultrafine fibers is increased, and the stability over time during polishing is improved. Preferably it is 200-800 MPa.

  In addition, the polymer elastic body is one of means for setting the bending elastic modulus to 150 to 800 MPa that the ultrafine fiber bundle in which 5 to 70 ultrafine fibers having an average fineness of 0.01 to 0.8 dtex or less are concentrated is present. Can be preferably employed. And it is more preferable that a part or the whole of the inside of the fiber bundle is converged by the polymer elastic body existing in the internal space of the fiber bundle.

  As a specific example of the polymer elastic body used in the polishing pad of the present invention, the flexural modulus of the polishing pad is 150 to 800 MPa, and after 60 minutes in the birec method water absorption height test according to JIS L1907-1994. If the water absorption height is appropriately selected such that the water absorption height is 10 mm or more, the following resins may be mentioned. For example, polyurethane resin, polyamide resin, (meth) acrylic ester resin, (meth) acrylic ester-styrene resin, (meth) acrylic ester-acrylonitrile resin, (meth) acrylic ester-olefin Resin, (meth) acrylic acid ester- (hydrogenated) isoprene resin, (meth) acrylic acid 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 resin An elastic body made of It is.

  As the polymer elastic body, a polymer elastic body having a water absorption rate of 0.2 to 5% by mass, more preferably 0.5 to 3% by mass when saturated water absorption is performed at 50 ° C. is particularly preferable. When the water absorption of the polymer elastic body is in such a range, the water absorption height in the Bayrec method water absorption height test is 10 mm or more, and the abrasive slurry has high wettability with respect to the polishing pad during polishing. While being maintained, it is possible to further suppress the bending elastic modulus from increasing and the rigidity from decreasing with time. Thereby, a high polishing rate, polishing uniformity and polishing stability can be maintained. The water absorption rate of the polymer elastic body is a water absorption rate when the polymer elastic body film that has been dried is immersed in water at room temperature and saturated and swelled, as will be described in detail later. Further, when two or more kinds of polymer elastic bodies are contained, it is theoretically calculated as the sum of values obtained by multiplying the water absorption of each polymer elastic body by the mass fraction.

  The polymer elastic body having such a water absorption rate can be obtained by adjusting the composition of the polymer constituting the polymer elastic body, the crosslinking density, or selecting the amount of hydrophilic functional groups.

  Specifically, for example, by introducing 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 into the polymer elastic body, The hydrophilicity can be adjusted. Thereby, the wettability with respect to the abrasive slurry of a polishing pad in the case of grinding | polishing can be improved.

  Such a hydrophilic group can be introduced into the polymer elastic body by copolymerizing a monomer component having a hydrophilic group as a monomer component for producing the polymer elastic body. The copolymerization ratio of the monomer component having such a hydrophilic group is 0.1 to 10% by mass, and further 0.5 to 5% by mass while minimizing swelling and softening due to water absorption. From the point that water absorption and wettability can be improved.

  As the polymer elastic body, a hydrogen-bonding polymer elastic body is preferable because of its high binding property to ultrafine fibers. The resin that forms the hydrogen-bonding polymer elastic body is a polymer elastic body that crystallizes or aggregates by hydrogen bonding, such as a polyurethane-based resin, a polyamide-based resin, and a polyvinyl alcohol-based resin. The hydrogen-bonding polymer elastic body has high adhesiveness, improves the shape retention of the fiber entangled body, and suppresses the fiber from coming off.

  The polymer elastic bodies may be used alone or in combination of two or more. Among these, polyurethane-based resins have excellent adhesive properties for focusing ultrafine fibers, constraining ultrafine fiber bundles, and binding fiber bundles. It is preferable from the viewpoint of increasing the stability over time in polishing. In particular, a polyurethane-based resin having 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 used for the rigidity, wettability, and polishing of the polishing pad. This is preferable from the viewpoint of high stability over time.

  Below, the case where a polyurethane-type resin is used as a polymeric 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 Kate diol, polyhexamethylene adipate diol, poly (3-methyl-1,5-pentylene adipate) diol, poly (3-methyl-1,5-pentylene sebacate) diol, isophthalic acid copolymer polyol, terephthalic acid Polyester polyols such as copolymer polyol, cyclohexanol copolymer polyol, polycaprolactone diol and copolymers thereof; polyhexamethylene carbonate diol, poly (3-methyl-1, -Polyethylene carbonate) diol, polypentamethylene carbonate diol, polytetramethylene carbonate diol, poly (methyl-1.8-octamethylene carbonate) diol, polynonane methylene carbonate diol, polycyclohexane carbonate, Polymer: Polyester carbonate polyol 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.

The polyol constituting the polyurethane resin used in the polishing pad of the present invention preferably contains 60 to 100% by mass of the total amount of polyol components of polycarbonate polyols such as alicyclic polycarbonate polyols and linear polycarbonate polyols. The amorphous polycarbonate polyol having a melting point of 0 ° C. or less contains 60 to 100% by mass of the total amount of the polyol component, and the values of the bending elastic modulus of the polishing pad and the bi-leg method water absorption height test are the main values. It is more preferable because it is easy to adjust within the scope of the invention and the stability over time during polishing is good. When the polycarbonate-based polyol component is 60% by mass or more based on the entire polyol component, it is preferable in that it is easily set to 150 MPa or more. Specifically, the polycarbonate polyol used is a polycarbonate polyol having a branch; poly (3-methyl-1,5-pentylene carbonate) diol, poly (methyl-1.8-octamethylene carbonate) diol, or poly (3- 3-methyl-1,5-pentylene carbonate) diol, poly (methyl-1.8-octamethylene carbonate) diol, polyhexamethylene carbonate diol, polypentamethylene carbonate diol, polytetramethylene carbonate diol, polynonane methylene carbonate Examples thereof include polycarbonate polyols obtained by copolymerizing polycarbonate polyols such as diol and polycyclohexane carbonate.
Moreover, it is also preferable to use about 0.1-10 mass% of the polyurethane resin containing a C5 or less, especially C3 or less polyalkylene glycol group from the point which the wettability with respect to water becomes especially favorable.

  Specific examples of the organic polyisocyanate include, for example, 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 by which a polishing pad 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, hydrazine, piperazine, hexamethylenediamine, isophoronediamine and derivatives thereof, and triamines such as ethylenetriamine are used in combination of two or more to provide high adhesion to fibers and high hardness polishing. This is preferable because a pad can be obtained. 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 elastic body, 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 polishing pad has excellent rigidity and wear resistance. The crosslinked structure is preferably formed in the heat treatment step after applying the polyurethane resin to the fiber entangled body 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.

  Moreover, the adhesiveness with the ultrafine fibers is increased to increase the rigidity of the fiber bundle, the glass transition temperature is set to −10 ° C. or lower, the storage elastic modulus at 23 ° C. to 50 ° C. is set to a range of 90 to 900 MPa, Since the water absorption when saturated with water absorption at 50 ° C. is 0.2 to 5% by mass, the content of the polymer polyol component in the polyurethane resin is 65% by mass or less, Furthermore, it is preferable that it is 60 mass% or less. Further, it is preferably 40% by mass or more, and more preferably 45% by mass or more from the viewpoint that the flexural modulus can be easily set to 150 MPa or more and generation of scratches can be suppressed by imparting appropriate elasticity.

  Polyurethane resins are penetrants, antifoaming agents, lubricants, water repellents, oil repellents, thickeners, extenders, curing accelerators, antioxidants, UV absorbers, antifungal agents, foaming agents, polyvinyl You may further contain water-soluble high molecular compounds, such as alcohol and carboxymethylcellulose, dye, a pigment, an inorganic fine particle.

  The polymer elastic body may contain two or more kinds of polymer elastic bodies in order to adjust performance, manufacturability and the like. Theoretically calculated as the sum of the values obtained by multiplying the storage elastic modulus of the molecular elastic body by the mass fraction.

  The polymer elastic body is preferably an aqueous polyurethane because the wettability of the polishing slurry is good, and the aqueous polyurethane preferably has an average particle diameter of 0.01 to 0.2 μm. When the average particle size is 0.01 μm or more, the water resistance is improved and the temporal stability during polishing is easily improved. When the average particle size is 0.2 μm or less, the restraint property of the fiber bundle is improved, the bending elastic modulus of the polishing pad is easily set to 150 MPa or more, the flatness is improved, and the pad life during polishing is extended, Stability over time is likely to improve. Moreover, in order to adjust the above average particle diameter or to obtain good wettability and water absorption, for example, the polymer elastic body is a carboxyl group, a sulfonic acid group, and a polyalkylene glycol group having 3 or less carbon atoms. It is preferable to contain at least one hydrophilic group selected from the group consisting of: and a structure having a communication hole inside the polishing pad. In order to set the water absorption height after 60 minutes in the Bayrec method water absorption height test to 10 mm or more, it can be preferably adjusted by the type and amount of these hydrophilic groups.

  And it is preferable at the point which is easy to adjust the bending elastic modulus of a polishing pad to the range of 150-800 MPa that the said ultrafine fiber entanglement body and the said polymer elastic body are 55 / 45-95 / 5 by mass ratio. When the mass ratio of the ultrafine fiber entanglement is 55 or more, there is a tendency that the temporal stability during polishing is improved and the polishing efficiency is improved. When the mass ratio of the ultrafine fiber entangled body is 95 or less, the binding force of the polymer elastic body in the fiber bundle is improved, the flatness is improved, and the pad wear during polishing is reduced, so that Stability is easy to improve. The range of 60/40 to 90/10 is particularly preferable.

Apparent density of the polishing pad of the present invention, it slurry retainability is good, and since the rigidity is high, 0.4~1.2g / cm ^3, further, the 0.5 to 1.0 g / cm ³ A range is preferable. The bending elastic modulus of the polishing pad of the present invention and the water absorption height after 60 minutes of the birec method water absorption height can also be adjusted by the apparent density of the pad. For example, when the apparent density of the polishing pad is 0.4 or more, the bending elastic modulus of the polishing pad can be easily increased to 150 MPa or more, and by 1.2 or less, the bending elastic modulus is controlled to 800 MPa or less. The water absorption height after 60 minutes of the birec method water absorption height is easily set to 10 mm or more.

  The average length of the fiber bundle is not particularly limited, but 100 mm or more, further 200 mm or more can easily increase the fiber density of the ultrafine fibers, and can easily increase the rigidity of the polishing pad. It is preferable from the point which can be performed and the loss of fibers can be suppressed. When the length of the fiber bundle is too short, it is difficult to increase the density of the ultrafine fibers, and a sufficiently high rigidity cannot be obtained, and the ultrafine fibers tend to be easily removed during polishing. An upper limit is not specifically limited, For example, when it contains the fiber entanglement body derived from the nonwoven fabric manufactured by the spunbond method mentioned later, unless it cut | disconnects physically, several m, several hundred m, several km Alternatively, longer fiber lengths may be included.

  The polishing pad of the present invention has a composite structure in which the fiber entangled body is filled with a polymer elastic body.

  In the polishing pad of the present invention, the ultrafine fiber forming the ultrafine fiber entangled body is preferably an ultrafine fiber bundle, and a polymer elastic body exists inside the ultrafine fiber bundle, and the ultrafine fiber bundle causes the ultrafine fiber bundle to exist. It is preferable that a part or most of the ultrafine fibers constituting the fiber bundle are constrained from the viewpoint that the bending elastic modulus of the polishing pad can be easily adjusted. When the ultrafine fiber bundle is constrained by the polymer elastic body, rigidity is imparted to the ultrafine fiber bundle, and the bending elastic modulus becomes 150 MPa or more, so that high planarization performance is obtained. Further, it is possible to prevent the fibers from coming off and to prevent the abrasive grains from agglomerating from agglomerating, thereby suppressing the scratches. Here, the ultrafine fibers are restrained by the polymer elastic body means a state in which most of the ultrafine fibers existing inside the fiber bundle are bonded and bound by the polymer elastic body existing inside the fiber bundle. means.

  Further, it is preferable that the plurality of fiber bundles are bound together by a polymer elastic body existing outside the fiber bundle and exist in a lump (bulk) shape, particularly in that the flexural modulus is easily set to 150 MPa or more. . Thus, the fiber bundles are bound to each other, so that the form stability of the polishing pad is improved and the polishing stability is improved.

  The converging / restraining state of the ultrafine fibers and the binding state of the fiber bundles can be easily confirmed by an electron micrograph of the cross section of the polishing pad.

  The polymer elastic body that binds the ultrafine fibers and the polymer elastic body that binds the ultrafine fiber bundles are preferably non-porous. The non-porous state is a state substantially free of voids (closed cells) as possessed by a porous or sponge-like (hereinafter also simply referred to as porous) polymer elastic body. Means. Specifically, it means that it is not a polymer elastic body having a large number of fine bubbles, for example, obtained by coagulating solvent-based polyurethane. It is easy to set the bending elastic modulus in the range of 150 to 800 MPa by increasing the binding force of the ultrafine fibers by making the polymer elastic body that focuses and restrains the ultrafine fibers or binds the ultrafine fiber bundles non-porous. . In addition, since the polishing stability is increased, and slurry scraps and pad scraps at the time of polishing are less likely to accumulate in the gaps, the polishing pad is difficult to wear, and therefore a high polishing rate can be maintained for a long time. Furthermore, since the adhesive strength with respect to the ultrafine fibers is increased, it is possible to suppress the occurrence of scratches due to the loss of the fibers. Furthermore, since higher rigidity is obtained, a polishing pad having excellent planarization performance can be obtained.

  The polishing pad of the present invention preferably has a water absorption of 10 to 80% by mass, more preferably 15 to 70% by mass when saturated and swollen with hot water at 50 ° C. When the water absorption is 10% by mass or more, the abrasive slurry tends to be retained, and the polishing rate tends to improve and the polishing uniformity tends to improve. When the water absorption is 80% by mass or less, the polishing rate is improved, and characteristics such as hardness are hardly changed during polishing, so that there is a tendency that the leveling performance is stable over time. .

The polishing pad of the present invention separates a fiber bundle existing near the surface by performing a pad flattening process by buffing or the like, a conditioning process before polishing using a pad dressing such as diamond, or a conditioning process during polishing. Alternatively, ultrafine fibers can be formed on the surface of the polishing pad by fibrillation. The fiber density of the ultrafine fibers on the surface of the polishing pad is preferably 600 fibers / mm ² or more, more preferably 1000 fibers / mm ² or more, and particularly preferably 2000 fibers / mm ² or more. 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 about 1,000,000 pieces / mm ² from the viewpoint of productivity. Further, the ultrafine fibers on the surface of the polishing pad may be raised or not raised. When the ultrafine fibers are raised, the surface of the polishing pad becomes softer and the effect of reducing scratches becomes higher. On the other hand, when the degree of napping of the ultrafine fibers 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.

[Production method of polishing pad]
Next, an example of the manufacturing method of the polishing pad of this invention is demonstrated in detail.

  The polishing pad of the present invention includes, for example, 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, and the long fiber web. A web entanglement step of forming a web entanglement sheet by entanglement with a plurality of sheets, and wet heat shrinkage to shrink the area shrinkage rate to 30% or more by subjecting the web entanglement sheet to wet heat shrinkage A treatment step, a fiber entanglement forming step for forming a fiber entangled body made of ultrafine fibers by dissolving the water-soluble thermoplastic resin in the web entangled sheet in hot water, It can be obtained by a method for producing a polishing pad comprising a polymer elastic body filling step of impregnating and drying and solidifying an aqueous liquid of a molecular elastic body.

  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. For this reason, the fiber density of the ultrafine fibers becomes dense. And the fiber entanglement body which consists of 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. Then, by impregnating and drying and solidifying the polymer liquid with an aqueous liquid of the polymer elastic body, the ultrafine fibers constituting the ultrafine fiber bundle are focused, and the ultrafine fiber bundles are also focused. In this way, a highly rigid polishing pad with high fiber density and converged ultrafine fibers can be 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 fiber is formed by dissolving or removing the water-soluble thermoplastic resin from the sea-island type composite fiber. 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 the composite fiber for forming the ultra-fine fiber, but a known ultra-fine fiber generating type fiber such as a multilayer laminated cross-section fiber is used instead of the sea-island type fiber. May be.

  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 a sea-island type composite fiber having a PVA-based resin as a water-soluble thermoplastic resin component is used, the ultrafine fibers formed by dissolving the PVA-based resin are greatly crimped. As a result, a fiber entangled body having a high fiber density can be obtained. In addition, when a sea-island type composite fiber containing a PVA resin as a water-soluble thermoplastic resin component is used, when the PVA resin is dissolved, the formed ultrafine fibers and polymer elastic body are not substantially decomposed or dissolved. Therefore, the physical properties of the ultrafine fiber and the polymer elastic body are hardly lowered. Furthermore, the environmental load is small. Further, even if a small amount remains, the adverse effect on the polishing performance is small, and conversely, the wettability of the polishing pad tends to be increased. Therefore, the amount of PVA resin relative to the pad is 0.01 to 0.2% by mass. The degree, preferably about 0.02 to 0.1% by mass.

  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 of showing melt viscosity and the high dissolution rate at the time of dissolution. 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 viewpoint of excellent point and 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 this point of view, it is preferable that the melting point of the PVA-based resin is not lower than 60 ° C. or even 30 ° C. or higher 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.

  As a specific example of the water-insoluble thermoplastic resin, various thermoplastic resins used for forming the ultrafine fibers constituting the polishing pad described above can be used.

  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 to the water-insoluble thermoplastic resin is within such a range, a high-density fiber entangled body can be obtained, and the formability of ultrafine 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 melt-kneaded by separate extruders, and molten resin strands are discharged simultaneously 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. Basis weight of the fiber web, it is obtained a uniform fiber-entangled body in the range of 20 to 500 g / m ^2, also from the viewpoint of industrial property.

(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 polishing pad, and specifically, for example, the handling property is in the range of 100 to 1500 g / m ² . From the point which is excellent in it.

The conditions for increasing the delamination force of the web entangled sheet are appropriately selected as the needle conditions such as the type and amount of the oil agent, the needle shape in the needle punch, the needle depth, and the number of punches. 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 depending on 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 fiber entangled body can be 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. This is preferable from the viewpoint of obtaining a fiber entangled body. Note that the delamination force is a measure of the degree of three-dimensional entanglement. When the delamination force is too small, the fiber density of the fiber entangled body is not sufficiently high. Moreover, although the upper limit of the delamination force of an entangled nonwoven fabric is not specifically limited, It is preferable that it is 30 kg / 2.5 cm or less from the point of an entanglement process efficiency.

  In addition, for the purpose of adjusting the hardness of the polishing pad, the web entangled sheet, which is a nonwoven fabric obtained as described above, is further made of ultrafine fibers, as long as the effects of the present invention are not impaired. An entangled nonwoven fabric in which knitted fabrics are entangled and integrated by performing entanglement treatment by needle punching treatment and / or high-pressure water flow treatment by overlapping knitted fabrics or woven fabrics (knitted fabrics), for example, knitted fabric / entangled nonwoven fabrics A laminated structure such as entangled nonwoven fabric / knitted fabric / entangled nonwoven fabric may be used as the web entangled sheet.

  The ultrafine fibers that constitute the knitted fabric are not particularly 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 fibers is particularly high.
The wet heat shrinkage treatment is preferably performed by steam heating. As the steam heating condition, it is preferable to perform heat treatment for 60 to 600 seconds at an ambient temperature of 60 to 130 ° C. and a relative humidity of 75% or more, and further a relative humidity of 90% or more. 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 fiberization treatment of the web entangled sheet, for the purpose of increasing the form stability of the web entangled sheet and reducing the porosity of the resulting polishing pad, If necessary, a fiber bundle may be bound in advance by impregnating the web-entangled sheet subjected to the shrink treatment with an aqueous liquid of a polymer elastic body and drying and solidifying it.

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. The polymer elastic body can be formed by impregnating the polymer elastic body in the state of an aqueous liquid and drying and coagulating it. Since the aqueous liquid of the polymer elastic body has a high concentration and a low viscosity and is excellent in impregnation permeability, it is easy to be filled with a high amount. Moreover, the adhesiveness with respect to a fiber is also excellent. 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 solution in which the component forming the polymer elastic body is dissolved in the aqueous medium, or the aqueous dispersion liquid in which the component forming the polymer elastic body is dispersed 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.

  The method for making the polyurethane resin into an aqueous solution or an 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, a method of imparting dispersibility to an aqueous medium to a polyurethane resin, or a surface activity of the polyurethane 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 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 gelation property can also be provided to a polyurethane resin by selecting the cloud point of surfactant suitably. However, when a large amount of surfactant is used, it may have an adverse effect on the polishing performance and its stability over time, so it is preferable to minimize the necessary amount.

  In this step, in order to form the polymer elastic body, it is preferable to use an aqueous liquid of the polymer elastic body instead of using an organic solvent solution of the polymer elastic body generally used conventionally. Thus, by using the aqueous liquid of the polymer elastic body, the resin liquid containing the polymer elastic body can be impregnated at a higher concentration. And thereby, the porosity of the obtained polishing pad can be sufficiently reduced, and the flexural modulus can be easily set in the range of 150 to 800 MPa.

  The solid content concentration of the aqueous liquid of the polymer elastic body is preferably 10% by mass or more, and more preferably 15% by mass or more, since the flexural modulus is easily in a desired range.

  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 a case, the particle size of the polymer elastic body of the aqueous liquid is adjusted; the kind and amount of ionic groups of the polymer elastic body are adjusted, or the stability is adjusted by pH or the like. Monovalent or divalent alkali metal salts or alkaline earth metal salts, nonionic emulsifiers, associative water-soluble thickeners, associative thermosensitive gelling agents such as water-soluble silicone compounds, water-soluble polyurethane compounds, Alternatively, migration can be suppressed by, for example, reducing the water dispersion stability at about 40 to 100 ° C. by using, for example, an organic substance or an inorganic substance whose pH is changed by heat. In addition, you may make it migrate so that 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 fibers by dissolving a water-soluble thermoplastic resin in hot water, will be described.

  This step is a step of forming ultrafine 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 this later step of filling the voids with the polymer elastic body, the ultrafine fibers are restrained by filling the polymer elastic body.

  The ultrafine fiber treatment is performed by hydrothermally treating a web entangled sheet or a composite of a web entangled sheet and a polymer elastic body with water, an aqueous alkaline solution, an acidic aqueous solution, etc. It is a process of dissolving and removing or decomposing and removing.

  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 fiber is formed by dissolving the water-soluble thermoplastic resin from the sea-island type composite fiber. Since the fiber density becomes dense due to this crimp, it is easy to obtain a high-density fiber entangled body, and it is easy to make the bending elastic modulus in the range of 150 to 800 MPa.

(6) Polymer elastic body filling step Next, the ultrafine fiber bundle is filled into the ultrafine fiber bundle formed from the ultrafine fibers, thereby restraining the ultrafine fiber and restraining the ultrafine fiber bundle. The process of binding the fiber bundles 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 are focused, the ultrafine fiber bundles are constrained, and the ultrafine fiber bundles are bound to each other. It is easy to reduce the modulus and to obtain a desired flexural modulus. When the ultrafine fibers form a fiber bundle, the ultrafine fibers are more easily focused and constrained because the aqueous polymer liquid is easily impregnated by 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 fibers in this step. In this way, a polishing pad is formed.

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

  The molding process and the flattening process are processes in which the obtained polishing pad is hot press molded to a predetermined thickness by grinding or cut into a predetermined outer shape. The polishing pad is preferably ground to a thickness of about 0.5 to 3 mm.

  The raising process is a process for separating the focused ultrafine fibers by applying mechanical frictional force or polishing force to the surface of the polishing pad with sandpaper, needle cloth, diamond or the like. By such raising treatment, the fiber bundle existing in the surface portion of the polishing pad is fibrillated, and a large number of ultrafine fibers are formed on the surface.

The laminating process is a process of adjusting rigidity by laminating the obtained polishing pad on a base material. For example, by laminating the polishing pad with an elastic sheet having low hardness, the global flatness of the surface to be polished (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 polishing pad in order to adjust the retention and discharge of the abrasive slurry.

  In the cleaning treatment, impurities such as particles and metal ions adhering to the obtained polishing pad are washed with cold water or warm water, or an aqueous solution containing an additive having a cleaning action such as a surfactant or the like. This is a process of washing with a solvent.

[Polishing method]
Below, it demonstrates as an example of grinding | polishing using the polishing pad of this embodiment.
The abrasive slurry is a slurry in which an abrasive such as silica, aluminum oxide, cerium oxide, zirconium oxide, silicon carbide, diamond or the like is 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. Moreover, when performing CMP, you may supply lubricating oil, a coolant, etc. with polishing slurry as needed.

The count of the abrasive slurry is preferably # 50 to # 1000, more preferably in the range of # 100 to # 1000, and the range of # 150 to # 1000 is the amount of wear loss in the thickness direction of the polishing pad surface during conditioning being 0.00. More preferable in terms of 3 μm / min or less. In conditioning with diamond abrasive grains, a method of reducing the grain size of diamonds by # 200 to # 1000 is particularly preferable. Conditioning may be performed before polishing the substrate 24 or during polishing. Further, the polishing of the substrate 24 to be polished and the conditioning of the polishing pad 10 may be performed alternately.
When the polishing pad of the present invention is used as a polishing pad for a semiconductor wafer, when conditioning the surface of the polishing pad, the polishing pad surface is conditioned at a thickness loss of 0.3 μm / min or less in the thickness direction. The polishing pad of the invention is preferable in that the polishing performance can be maintained in a stable state for a long time. In order to reduce the wear loss below the above numerical value, in addition to adjusting the count of the abrasive slurry, the polishing pad of the present invention has good wettability to water, so it is possible to employ conditioning using a water flow. It is. As a conditioning method using water flow, for example, high pressure water cleaning such as high pressure jet water cleaning, high pressure micro jet water cleaning, high pressure bubble jet water cleaning, and water spray cleaning, ultrasonic water cleaning, nylon brush, etc. were used. Brush cleaning or the like can be employed.
Among them, since the polishing pad of the present invention has an ultrafine fiber entangled body made of ultrafine fibers having an average fineness of 0.01 to 0.8 dtex on the surface, compared with the conventional conditioning method, It is preferable to adopt a mild conditioning condition such that the wear loss is adjusted to a speed of 0 to 0.3 μm / min. Specifically, in addition to those described above, a blocky type diamond dresser, a method with a low conditioning pressure, a method for shortening the conditioning time, and a generally gentle conditioning treatment compared to the diamond dressing treatment. High pressure water cleaning such as high pressure high pressure jet cleaning, high pressure micro jet cleaning, high pressure bubble jet cleaning, spray cleaning, ultrasonic cleaning, brush cleaning, etc. can also be adopted. Is preferred. The wear loss in the thickness direction of the polishing pad surface was measured from the average of 10 cross-sectional photographs obtained by enlarging the difference in pad thickness before and after conditioning 200 times and divided by the conditioning time (minutes). Ask for.

  The polishing pad of the present invention includes a silicon wafer, a compound semiconductor wafer, a semiconductor wafer, a semiconductor device, a liquid crystal member, an optical element, a crystal, an optical substrate, an electronic circuit substrate, an electronic circuit mask substrate, a multilayer wiring substrate, a hard disk, a MEMS (micro- Electro-Mechanical Systems) It is preferably used for polishing substrates and the like.

  Specific examples of semiconductor wafers and semiconductor devices include, for example, insulating films such as silicon, silicon oxide, silicon oxyfluoride, and organic polymers; wiring material metal films such as copper, aluminum, and tungsten; tantalum, titanium, tantalum nitride, and nitride Examples thereof include a base material having a barrier metal film such as titanium on the surface.

  In the polishing, it is used for any polishing such as primary polishing, secondary polishing (adjustment polishing), finish polishing, mirror polishing and the like. Moreover, as a grinding | polishing part, any of the surface of a base material, a back surface, and an end surface may be sufficient.

  Hereinafter, the present invention will be specifically described by way of examples. In addition, this invention is not limited at all by the Example. Moreover, the obtained polishing pad was evaluated by the following evaluation methods.

[Evaluation methods]
(1) Confirmation of average fineness of ultrafine fibers and converging state of ultrafine fibers inside fiber bundle The obtained polishing pad 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. Then, the cut surface was observed with a scanning electron microscope (SEM) at 500 to 1000 times, and an image thereof was taken. 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, and the density was calculated from the density of the resin forming the fiber. In addition, when the obtained image is observed, not only the ultrafine fibers constituting the outer periphery of the fiber bundle but also the state in which the ultrafine fibers inside are bonded and integrated by the polymer elastic body is focused. "No" when the polymer elastic body does not exist inside the fiber bundle or only a few exist, and the state where the ultrafine fibers are hardly bonded and integrated is not focused. It was judged.

(2) Storage elastic modulus of polymer elastic body at 23 ° C. and 50 ° C. A film sample having a length of 4 cm × width 0.5 cm × thickness 400 μm ± 100 μm was prepared from the polymer elastic body constituting the polishing pad. Then, after measuring the sample thickness with a micrometer, using a dynamic viscoelasticity measuring device (DVE Rheospectr, manufactured by Rheology Co., Ltd.), the temperature is 23 ° C. under conditions of a frequency of 11 Hz and a temperature rising rate of 3 ° C./min. The dynamic viscoelastic modulus at 50 ° C. was measured, and the storage elastic modulus was calculated. In addition, when using 2 types of polymer elastic bodies, the sample was created and measured separately, respectively, and the sum which multiplied the mass ratio was made into the value of the elastic modulus of a polymer elastic body.

(3) Glass transition temperature of polymer elastic body A film having a length of 4 cm, a width of 0.5 cm, and a thickness of 400 μm ± 100 μm was prepared from the polymer elastic body constituting the polishing pad. Then, after measuring the sample thickness with a micrometer, using a dynamic viscoelasticity measuring device (DVE Rheospectr, manufactured by Rheology Co., Ltd.), the sample thickness is dynamically adjusted under conditions of a frequency of 11 Hz and a temperature rising rate of 3 ° C./min. Viscoelasticity was measured, and the main dispersion peak temperature of the loss elastic modulus was taken as the glass transition temperature. In addition, when using 2 types of polymer elastic bodies, the sample was created and measured separately, respectively, and the sum which multiplied the mass ratio was made into the value of the glass transition temperature of a polymer elastic body.

(4) Water Absorption Rate of Polymer Elastic Body A 200 μm thick film obtained by drying the polymer elastic body at 50 ° C. was heat-treated at 130 ° C. for 30 minutes, and then subjected to conditions of 20 ° C. and 65% RH. The sample left for 3 days was used as a dry sample, and the dry sample was immersed in water at 50 ° C. for 2 days. Then, the water-swollen sample was obtained after wiping off excess water droplets and the like on the outermost surface of the film immediately after being taken out of water at 50 ° C. with JK Wiper 150-S (manufactured by Crecia Corporation). The masses of the dried sample and the water-swelled sample were measured, and the water absorption rate was determined according to the following formula. In addition, when using 2 types of polymer elastic bodies, the sample was created and measured separately, respectively, and the sum multiplied by the mass ratio was used as the water absorption value of the polymer elastic body.

Water absorption (%) = [(mass of water swelled sample−mass of dried sample) / mass of dried sample] × 100

(5) Average particle diameter of aqueous polyurethane Measured by dynamic light scattering method using “ELS-800” manufactured by Otsuka Chemical Co., Ltd., cumulant method (“Colloid Chemistry Volume IV Colloid Chemistry Experiment Method” published by Tokyo Chemical Doujinsha) The average particle size of the water-dispersed polymer elastic body was measured.When two types of polymer elastic bodies were used, the sample was measured separately and the sum of the mass ratio was multiplied. Is the value of the average particle size of the polymer elastic body.

(6) Flexural modulus
AG-5000B (manufactured by Shimadzu Corporation), test mode: single, test type: 3-point bending, control: stroke, head speed: 0.6 mm / min, load cell: 500 kg, between chucks: 2.2 cm, number of tests: The flexural modulus was measured with five pieces, and the average value of the five measurements was taken as the flexural modulus. In addition, the sample measured the vertical direction and the horizontal direction, respectively, and made it the average value.

(7) Water absorption height after 60 minutes at the birec method water absorption height The water absorption height after 60 minutes was measured in the birec method water absorption height test based on JIS L1907-1994. The measurement sample was measured four times, and the average value was taken as the water absorption height.

(8) Polishing performance evaluation of polishing pad After sticking an adhesive tape on the back surface of a circular polishing pad, it was mounted on a CMP polishing apparatus ("PP0-60S" manufactured by Nomura Seisakusho Co., Ltd.). Then, using a diamond dresser with count # 200 (MEC200L manufactured by Mitsubishi Materials Corporation), a polishing pad for 18 minutes while flowing distilled water at a rate of 120 mL / min under conditions of a pressure of 177 kPa and a dresser rotation speed of 110 rpm Conditioning was performed by grinding the surface.
Next, a diameter having an oxide film surface is supplied while supplying Cabot abrasive slurry SS12 at a rate of 120 ml / min under the conditions of a platen rotation speed of 50 rotations / minute, a head rotation speed of 49 rotations / minute, and a polishing pressure of 35 kPa. A 6 inch silicon wafer was polished for 100 seconds. And the thickness of the arbitrary 49 points in the silicon wafer surface which has the oxide film surface after grinding | polishing was measured, and the grinding | polishing rate (nm / min) was calculated | required by remove | dividing the polished thickness in each point by grinding | polishing time. . The average value of the 49 polishing rates was defined as the polishing rate (R), and its standard deviation (σ) was determined.

And flatness was evaluated by the following formula. In addition, it shows that it is excellent in planarization performance, so that the value of flatness is small.
Flatness (%) = (σ / R) × 100

  Next, the polished polishing pad was left in a wet state at 25 ° C. for 24 hours. Then, after conditioning, the polishing rate (R) and flatness after polishing again were determined.

  Further, conditioning and polishing were alternately repeated 300 times, and the polishing rate (R) and flatness at the 300th polishing were determined.

  Further, by measuring the number of scratches having a size of 0.16 μm or more present on the surface of the silicon wafer having the oxide film after polishing, using a wafer surface inspection apparatus Surfscan SP1 (manufactured by KLA-Tencor) The scratch property was evaluated.

[Example 1]
Water-soluble thermoplastic polyvinyl alcohol resin (hereinafter referred to as PVA resin) and isophthalic acid-modified polyethylene terephthalate having a degree of modification of 6 mol% (water absorption 1% by mass when saturated with water at 50 ° C., glass transition) (Temperature 77 ° C.) (hereinafter referred to as modified PET) was discharged from the melt composite spinning die at a ratio of 20:80 (mass ratio) to form a sea-island composite fiber. The melt compound spinning die had 64 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 40 g / m ² is collected. )was gotten.

The resulting spunbonded sheets stacked 12 sheets by cross lapping, the total basis weight was produced overlay web 480 g / m ^2. And the needle | hook breaking prevention oil agent was sprayed on the obtained overlapping web. Next, using a needle needle with a needle count of 42 with one barb and a needle needle with a needle count of 42 with six barbs, the overlap web is entangled by needle punching at 2000 punches / cm ² . Thus, a web entangled sheet was obtained. The basis weight of the obtained web entangled sheet was 760 g / m ² . Moreover, the area shrinkage rate by the needle punch process was 38%.

Next, the obtained web-entangled sheet was steam-treated for 90 seconds under the conditions of 70 ° C. and 90% RH. The area shrinkage rate at this time was 45%. And after drying in 120 degreeC oven, the web entanglement sheet | seat of the areal weight 1350g / m < ² >, apparent density 0.75g / cm < ³ >, thickness 1.8mm was obtained by heat-pressing at 120 degreeC. .

Next, the hot-pressed web entangled sheet was impregnated with an aqueous dispersion of polyurethane elastic body A (solid content concentration 20% by mass) as the first polyurethane elastic body. The polyurethane elastic body A is 99.7: 0.3 (molar ratio) of an amorphous polycarbonate-based polyol and a polyalkylene glycol having 2 to 3 carbon atoms, and the carboxyl group-containing monomer is 1. An amorphous polycarbonate-based non-yellowing polyurethane resin containing 5 wt%. The polyurethane elastic body A has a water absorption rate of 3% by mass, a storage elastic modulus at 23 ° C. of 300 MPa, a storage elastic modulus at 50 ° C. of 150 MPa, a glass transition temperature of −20 ° C., and the average particle size of the aqueous dispersion is 0.03 μm. is there. At this time, the solid content adhesion amount of the aqueous dispersion was 12% by mass with respect to the mass of the web-entangled sheet. The web entangled sheet impregnated with the aqueous dispersion was dried and solidified at 90 ° C. and 50% RH, and further dried at 140 ° C., with a basis weight of 1500 g / m ² and an apparent density of 0.83 g / A sheet of cm ³ and a thickness of 1.8 mm was obtained.

Next, the PVA resin is dissolved and removed by continuously performing a nip treatment for 10 minutes while immersing the web entangled sheet filled with the polyurethane elastic body A in 95 ° C. hot water, and further drying. Thus, a composite of polyurethane elastic body A and fiber entangled body having an average fineness of ultrafine fibers of 0.04 dtex, a basis weight of 1200 g / m ² , an apparent density of 0.63 g / cm ³ and a thickness of 1.9 mm was obtained. .

Then, the composite was impregnated with an aqueous dispersion of polyurethane elastic body B (solid content concentration 20% by mass) as a second polyurethane elastic body. The polyurethane elastic body B was obtained by adding 100 parts by mass of a non-yellowing polyurethane resin obtained from a composition containing an amorphous polycarbonate polyol as a polyol component and 1.7% by mass of a carboxyl group-containing monomer. It is a polyurethane resin having a crosslinked structure formed by adding a mass part and heat-treating it. The polyurethane elastic body B has a water absorption rate of 2% by mass, a storage elastic modulus at 23 ° C. of 480 MPa, a storage elastic modulus at 50 ° C. of 330 MPa, a glass transition temperature of −25 ° C., and the average particle size of the aqueous dispersion is 0.05 μm. there were. At this time, the solid content adhesion amount of the aqueous dispersion was 13% by mass relative to the mass of the composite. Next, the web entangled sheet impregnated with the aqueous dispersion was coagulated at 90 ° C. in an atmosphere of 50% RH, and further dried at 140 ° C. Then, it was hot pressed at 150 ° C. to obtain a polishing pad precursor. The resulting polishing pad precursor has a basis weight of 1390 g / m ² and an apparent density of 0.82 g / cm.
³ and the thickness was 1.7 m.

The obtained polishing pad precursor is ground for surface flattening to have a basis weight of 1150 g / m ² , an apparent density of 0.82 g / cm ³ , and a thickness of 1.4 mm, and evaluated by an evaluation method described later. did. The results are shown in Table 1. Furthermore, a circular polishing pad was obtained by cutting into a circular shape with a diameter of 51 cm and forming grooves with a width of 2.0 mm and a depth of 1.0 mm on the surface in a lattice shape at intervals of 15.0 mm. The mass ratio between the fiber entangled body and the polyurethane elastic body was 77/23, and the ratio between the polymer elastic body A and the polymer elastic body B was 51:49. Moreover, the surface of the obtained polishing pad was measured using a diamond dresser of # 200 (MEC200L manufactured by Mitsubishi Materials Corporation) under the conditions of a pressure of 177 kPa and a dresser rotation speed of 110 rotations / minute, and distilled water of 120 mL / minute. When conditioning was performed by grinding the surface of the polishing pad for 18 minutes while flowing at a speed, the amount of wear loss in the thickness direction of the surface of the polishing pad was 0.25 μm / min.

[Example 2]
The same process as in Example 1 was performed until the web entangled sheet was created.

Next, the web entangled sheet that has been hot-pressed without impregnating the polyurethane elastic body is immersed in hot water at 95 ° C. for 10 minutes to dissolve and remove the PVA-based resin. An entangled body was obtained. Then, the obtained fiber entangled body was impregnated with an aqueous dispersion of polyurethane elastic body B (solid content concentration 35% by mass). At this time, the solid content adhesion amount of the aqueous dispersion was 24% by mass relative to the mass of the fiber entangled body. Next, the fiber entangled body impregnated with the aqueous dispersion was dried at 120 ° C., and further hot pressed at 140 ° C. to obtain a polishing pad precursor. The obtained polishing pad precursor was post-processed in the same manner as in Example 3 to obtain a polishing pad having a basis weight of 950 g / m ² , an apparent density of 0.68 g / cm ³ , and a thickness of 1.4 mm. . The obtained polishing pad was evaluated by the evaluation method described later. The results are shown in Table 1. Furthermore, a circular polishing pad was obtained by cutting into a circular shape with a diameter of 51 cm and forming grooves with a width of 2.0 mm and a depth of 1.0 mm on the surface in a lattice shape at intervals of 15.0 mm.

[Example 3]
As a first polyurethane elastic body, instead of the polyurethane elastic body A, a polyether-based polyalkylene glycol and a polycarbonate-based polyol are 88:12 (molar ratio), and a carboxyl group-containing monomer is 1.2 wt% by weight. Amorphous polycarbonate non-yellowing polyurethane elastomer C containing a crosslinked structure (water absorption 4%, storage elastic modulus at 23 ° C. is 250 MPa, storage elastic modulus at 50 ° C. is 100 MPa, glass transition temperature is −30 ° C., water dispersion The average particle size of the liquid is 0.03 μm, and instead of the polyurethane elastic body B, the polyurethane elastic body D having an increased polyol component of the polyurethane elastic body B (water absorption 4%, 23%) is used as the second polyurethane elastic body. The storage elastic modulus at 300 ° C. is 300 MPa, the storage elastic modulus at 50 ° C. is 125 MPa, and the glass transition temperature is −30 ° C. Except for using an aqueous dispersion having an average particle size of 0.05 μm, a polishing pad was prepared in the same manner as in Example 1. The obtained polishing pad was evaluated by an evaluation method described later. Show.

[Example 4]
Melting water-soluble thermoplastic polyvinyl alcohol resin and isophthalic acid-modified polyethylene terephthalate having a modification degree of 6 mol% in a ratio of 20:80 (mass ratio) with 6 islands / fiber. A polishing pad was obtained in the same manner as in Example 1 except for spinning. The fineness of the ultrafine fiber was 0.42 dtex. The obtained polishing pad was evaluated by the evaluation method described later. The results are shown in Table 1.

[Comparative Example 1]
By melt-spinning modified PET, PET long fibers having an average fineness of 2 dtex are melt-spun, and the obtained long fibers are collected on a net to obtain a spunbond sheet (long fiber web) having a basis weight of 30 g / m ^2. )

A laminated web was produced from the obtained spunbond sheet in the same manner as in Example 1. And the web entangled sheet was obtained by carrying out the needle punch process and entangled the obtained overlapping web similarly to Example 1. FIG. The basis weight of the obtained web entangled sheet was 840 g / m ² , and the delamination force was 12 kg / 2.5 cm. Next, the obtained web-entangled sheet was steam-treated for 90 seconds under the conditions of 70 ° C. and 95% RH. And after making it dry in 140 degreeC oven, the web entangled sheet was obtained by hot-pressing at 140 degreeC.

  Next, the hot-pressed web entangled sheet was impregnated with an aqueous dispersion of polyurethane elastic body A (solid content concentration 40% by mass). At this time, the solid content adhesion amount of the aqueous dispersion was 17% by mass with respect to the mass of the web entangled sheet. The web-entangled sheet impregnated with the aqueous dispersion was coagulated at 90 ° C. and 90% RH atmosphere, and further dried at 140 ° C. Then, a buffing process was performed to flatten the front surface and the back surface to obtain a polishing pad. The obtained polishing pad was evaluated by the evaluation method described later. The results are shown in Table 2.

[Comparative Example 2]
As a polymer elastic body, instead of forming a polyurethane elastic body using an aqueous dispersion of polyurethane elastic bodies A and B, a polyurethane resin solution (12% concentration, 23 ° C., dissolved in N, N-dimethylformamide solution) is used. Except that the storage elastic modulus was 150 MPa, the storage elastic modulus at 50 ° C. was 50 MPa, and the amorphous polycarbonate-based yellowing polyurethane resin was impregnated and wet coagulated in a mixed liquid of DMF and water at 40 ° C. to form a polyurethane elastic body. A polishing pad was prepared in the same manner as in Example 1. The obtained polishing pad was evaluated by the evaluation method described later. The results are shown in Table 2.

[Comparative Example 3]
Instead of polyurethane elastic bodies A and B, polyurethane elastic body F in which the polyol component of polyurethane elastic body D is increased to 65% by mass (water absorption 8%, storage elastic modulus at 23 ° C. is 80 MPa, storage elastic modulus at 50 ° C. Was used in the same manner as in Example 1, except that 30 MPa, glass transition temperature of −32 ° C., and the average particle size of the aqueous dispersion were 0.03 μm. The obtained polishing pad was evaluated by the evaluation method described later. The results are shown in Table 2.

[Comparative Example 4]
A polishing pad obtained in the same manner as in Example 1 except that the polyurethane elastic body B was not applied was evaluated by an evaluation method described later. The results are shown in Table 2. In addition, there was almost no polyurethane elastic body inside the fiber bundle in the obtained polishing pad, and the ultrafine fibers were not substantially focused.

[Comparative Example 5]
Instead of polyurethane elastic body B, polyurethane elastic body F (polyurethane elastic body D having a water absorption of 1% and a storage elastic modulus of 23 ° C. having a polycarbonate component of hexamethylene carbonate diol reduced to about 30% by mass) A polishing pad was prepared in the same manner as in Example 1 except that 1000 MPa, storage elastic modulus at 50 ° C. was 200 MPa, glass transition temperature was 0 ° C., and the average particle size of the aqueous dispersion was 0.08 μm. The obtained polishing pad was evaluated by the evaluation method described later. The results are shown in Table 2.

  The results are shown in Table 1 and Table 2.

[Example 5]
The polishing performance of the polishing pad was evaluated in the same manner except that the polishing conditions were changed using the polishing pads obtained in Examples 1 to 4.
The polishing conditions are as follows.

(1) Evaluation was made in the same manner except that the silicon wafer having an oxide film was changed to a bare silicon wafer and the slurry used for polishing was changed to Granzox 1103 made by Fujimi.

(2) The slurry used for polishing was evaluated in the same manner except that the slurry was changed to Showa Denko polishing slurry GPL-C1010 and the slurry flow rate was changed to 200 ml.

  The results are shown in Table 3.

  The polishing pad according to the present invention includes various products such as flattened and mirror-finished devices and various substrates, such as semiconductor substrates, semiconductor devices, compound semiconductor devices, compound semiconductor substrates, compound semiconductor products, LED substrates, and LEDs. It can be used as a polishing pad for polishing products, silicon wafers, hard disk substrates, glass substrates, glass products, metal substrates, metal products, plastic substrates, plastic products, ceramic substrates, ceramic products and the like.

Claims (5)

  A birec method water absorption formed of an ultrafine fiber entangled body composed of ultrafine fibers having an average fineness of 0.01 to 0.8 dtex and a polymer elastic body, having a flexural modulus of 150 to 800 MPa and conforming to JIS L1907-1994. A polishing pad having a water absorption height of 10 mm or more after 60 minutes in a height test.   The ultrafine fiber entangled body is composed of an ultrafine fiber bundle in which 5 to 70 ultrafine fibers having an average fineness of 0.01 to 0.8 dtex or less are converged, and the polymer elastic body is present inside the ultrafine fiber bundle. The polishing pad according to claim 1.   The polymer elastic body is an aqueous polyurethane containing 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, and the average particle size of the aqueous polyurethane The polishing pad according to claim 1 or 2, mainly comprising an aqueous polyurethane having a diameter of 0.01 to 0.2 µm.   The polishing pad according to any one of claims 1 to 3, wherein the polymer elastic body has a storage elastic modulus in a range of 90 to 900 MPa at 23 ° C and 50 ° C.   5. A semiconductor, characterized in that, when conditioning the surface of the polishing pad according to any one of claims 1 to 4, conditioning loss of the polishing pad surface in the thickness direction is 0.3 [mu] m / min or less. A method of conditioning a polishing pad for a wafer.