TWI513871B - Polishing pad and chemical mechanical polishing method - Google Patents

Description

Polishing pad and chemical mechanical polishing method

The present invention relates to a polishing pad for planarization or mirroring of a substrate to be polished, and a chemical mechanical polishing method using the same. More specifically, for example, a non-woven type polishing pad which is preferably used for surface polishing of a surface of a semiconductor wafer or polishing of a wiring substrate.

In recent years, with the high integration of integrated circuits and multilayer wiring, high flatness on semiconductor wafers in which integrated circuits are formed is being sought.

Chemical mechanical polishing (CMP) is widely used in the grinding method for grinding semiconductor wafers. The CMP is a method of polishing by polishing a polishing pad in a planetary gear shape while dropping a polishing paste on the surface of a substrate to be polished which is rotating.

The polishing pad used in the conventional CMP is a polishing pad composed of a polymer foam molded body having the closed cell structure disclosed in the following Patent Documents 1 to 4; or a non-woven type polishing as disclosed in the following Patent Documents 5 to 18. pad.

For example, a polishing pad composed of a foamed molded article is produced by casting foam molding of a two-liquid curing type polyurethane. Such a polishing pad also has high rigidity by using a non-woven type polishing pad. Therefore, at the time of polishing, since the load is easily applied to the convex portion of the substrate to be polished, the polishing rate (polishing speed) is high. However, the polishing pad composed of the foamed molded article has a drawback in that in the case where the agglomerated abrasive grains are present on the polished surface, since the load is selectively applied to the aggregated abrasive grains, it becomes easy to be ground. Scratches on the surface. Therefore, as disclosed in Non-Patent Document 1, there is a disadvantage that scratching is particularly likely to occur in the case of a substrate having a copper wiring which is easily scratched or a low dielectric constant material having a weak interface at the polishing interface. Or the interface is stripped. Further, in the case of casting foam molding, it is difficult to obtain a foamed molded body which is uniformly foamed, and there is a disadvantage that polishing unevenness in the polishing surface tends to be high.

On the other hand, for example, the non-woven type polishing pad contains a non-woven fabric and a polymeric elastomer such as a polyurethane resin provided inside the nonwoven fabric. Such a non-woven type polishing pad also has superior flexibility as compared with a polishing pad composed of a foamed molded body. Therefore, even if the aggregated abrasive grains are present on the polished surface, it is difficult to selectively apply the load to the aggregated abrasive grains, and it is difficult to cause scratches on the polished surface. However, the non-woven type polishing pad has a problem that flattening performance is not sufficiently high. This is considered to be due to the following reasons: since the non-woven type polishing pad is soft, when it is ground, it deforms with the surface shape of the substrate to be polished, or the polishing property changes with time, and the stress is locally concentrated on the portion where the fiber exists. . In addition, the non-woven type polishing pad also has a problem that the polishing rate is low.

Further, the following Patent Documents 15 to 18 disclose a non-woven type polishing pad which uses a non-woven fabric formed of a fiber bundle of ultrafine fibers for the purpose of realizing a polishing process which is more precise and more precise. Specifically, for example, Patent Document 15 discloses a nonwoven fabric formed by winding a fiber bundle of a polyester microfiber having an average fineness of 0.0001 to 0.01 dtex, and a polyamine which is present in the inner space of the nonwoven fabric. A polishing pad made of a sheet of a polymer elastomer having an acid ester as a main component.

Patent Document 1: Japanese Patent Laid-Open Publication No. 2000-178374

Patent Document 2: Japanese Patent Laid-Open Publication No. 2000-248034

Patent Document 3: Japanese Patent Laid-Open Publication No. 2001-89548

Patent Document 4: Japanese Patent Laid-Open No. Hei 11-322878

Patent Document 5: Japanese Patent Laid-Open Publication No. 2002-9026

Patent Document 6: Japanese Patent Laid-Open No. Hei 11-99479

Patent Document 7: Japanese Patent Laid-Open Publication No. 2005-212055

Patent Document 8: Japanese Patent Laid-Open No. Hei 3-234475

Patent Document 9: Japanese Patent Laid-Open No. Hei 10-128674

Patent Document 10: Japanese Patent Laid-Open Publication No. 2004-311731

Patent Document 11: Japanese Patent Laid-Open No. Hei 10-225864

Patent Document 12: Japanese Patent Laid-Open Publication No. 2005-518286

Patent Document 13: Japanese Patent Laid-Open Publication No. 2003-201676

Patent Document 14: Japanese Patent Laid-Open Publication No. 2005-334997

Patent Document 15: Japanese Patent Laid-Open Publication No. 2007-54910

Patent Document 16: Japanese Patent Laid-Open Publication No. 2003-170347

Patent Document 17: Japanese Patent Laid-Open Publication No. 2004-130395

Patent Document 18: Japanese Patent Laid-Open Publication No. 2002-172555

Non-Patent Document 1: Kashiwagi Masahiro, "Science of CMP", Science Foram Co., Ltd., August 20, 1997, p. 113 to 119

As described above, the CMP system using the polishing pad composed of the foamed molded article has an excellent polishing rate, but has a problem that scratching is likely to occur and polishing unevenness in the polishing surface tends to be high. Further, CMP using a non-woven type polishing pad is difficult to give a scratch, but has a low polishing rate and has a problem that the wear resistance is low and the life is short.

The present invention has been made to solve such a problem, and an object thereof is to provide a non-woven type polishing pad having excellent cut resistance, which can attain a high polishing rate, low unevenness of polishing in a polishing surface, and can be easily realized. The CMP that caused the scratch.

One aspect of the present invention is a polishing pad comprising a nonwoven fabric formed of a fiber bundle of an ultrafine fiber having an average cross-sectional area of 0.1 to 30 μm ² and a polymeric elastomer imparted inside the nonwoven fabric; The longitudinal section, the average number density D ₁ of the cross section of the fiber bundle in the thickness region from the first surface to within 20% in the thickness direction is 1000 to 5000 / mm ² ; D ₁ and from the opposite to the first surface The ratio (D ₁ /D ₂ ) of the average number density D ₂ of the cross section of the fiber bundle in the thickness region of the second surface up to 20% in the thickness direction is 1.3 to 5.

In another aspect of the present invention, a chemical mechanical polishing method is a chemical mechanical polishing method for a substrate; the first surface of the polishing pad is brought into contact with the substrate while the polishing paste is dropped on the surface of the substrate. Grinding the surface.

The objects, features, aspects and advantages of the present invention will become more apparent from

By polishing the surface of the substrate using the polishing pad of the present invention, high-precision polishing processing can be realized at a high polishing rate. In addition, scratches are less likely to remain on the surface of the substrate to be polished. Further, the polishing surface of the polishing pad has high abrasion resistance.

An embodiment of the polishing pad according to the present invention will be described in detail with reference to the drawings. Fig. 1 is a schematic longitudinal cross-sectional view of a polishing pad 10 of the present embodiment. In Fig. 1, 1 is a nonwoven fabric formed of a fiber bundle 1b of an ultrafine fiber 1a having an average cross-sectional view of 0.1 to 30 μm ² , 2 is a polymer elastic body imparted inside the nonwoven fabric 1, and a 3 type polishing pad 10 is provided. The polishing surface of the first surface is a fixing surface of the second surface of the polishing pad 10. Further, R ₁ is a thickness region from the surface of the polishing surface 3 to 20% in the thickness direction, and R ₂ is a thickness region from the surface of the fixing surface 4 of the polishing surface 3 to 20% in the thickness direction. . Further, R ₃ is a thickness region from the surface of the polishing surface 3 to 40 to 60% in the thickness direction. Further, the polishing surface 3 is in contact with the surface of the substrate to be polished during polishing, and the fixing surface 4 is fixed to the surface of the rotating fixed disk of the CMP apparatus using a double-sided adhesive tape or the like.

As shown in Fig. 1, the polishing pad 10 includes a nonwoven fabric 1 made of the fiber bundle 1b of the ultrafine fibers 1 and a composite sheet of the polymer elastic body 2 provided inside the nonwoven fabric 1. The thickness of the polishing pad is appropriately selected depending on the use, and is, for example, preferably about 0.5 to 3 mm, and more preferably about 0.7 to 2 mm. Further, the longitudinal section of the polishing pad 10 in the thickness direction is an average number density D ₁ of the fiber bundle cross-section in the thickness region from the surface of the polishing surface 3 to 20% in the thickness direction of 1,000 to 5,000 / mm ² . The average number density D _1, and the pairs at the surface of the fixing surface polishing surface 3 of 4, the average number density thickness region the thickness direction is within 20% of the of the fiber bundle cross section D ₂ ratio (D ₁ / D ₂ ) is 1.3 to 5. In this manner, the density of the fiber bundle 1b existing in the vicinity of the surface of the polishing surface 3 of the polishing pad 10 is higher than the density of the fiber bundle 1b existing in the vicinity of the surface of the fixing surface 4. By making the density of the fiber bundle 1b existing in the vicinity of the surface of the polishing surface 3 high, the rigidity and hardness of the polishing surface 3 side can be made higher than the side of the fixed surface 4. Further, by increasing the rigidity of the polishing surface 3 side, the pressure for inserting the abrasive grains on the surface of the substrate to be polished is increased, the polishing rate is increased, and the abrasion resistance is also improved. In addition, by making the density of the fiber bundle 1b existing in the vicinity of the surface of the fixing surface 4 low, it is difficult to cause scratching on the surface due to moderate followability or suitability to the surface of the substrate to be polished.

The average number density D ₁ in the longitudinal section of the polishing pad 10 in the thickness direction was calculated as follows. The polishing pad 10 was cut in parallel with the thickness direction using a blade, and the cut surface was observed by a scanning electron microscope (SEM) at 100 to 1000 times. Further, in this case, it is also possible to perform dyeing of the cut surface by using a dye such as ruthenium oxide. Then, from the image taken is calculated every predetermined number of cross-sectional area of the fiber bundle 1b and in the thickness direction is within 20% of the thickness of the region R as viewed from the surface of the polishing surface ₁ to 3, the fiber bundle is calculated 1b The number density (number/mm ² ) of the number of cross sections per unit area. Further, in the case where the polishing surface is subjected to the velvet treatment, the number density is calculated from the root portion of the fine fiber or the fiber bundle of the pile to the thickness region within 20% in the thickness direction. Further, in the case where grooves or holes are formed in the surface of the polishing pad, the number density is calculated in a portion where no groove or hole is formed. Such a number density is calculated everywhere at several positions (for example, five positions), and the number of the obtained number density is averaged to the average number density D ₁ . Similarly, the average number density D ₂ is calculated by calculating the number of cross sections of the fiber bundle per predetermined area observed from the surface of the fixing surface 4 and the thickness region R ₂ within 20% in the thickness direction, and calculating the unit area per unit area. The number density of the cross-sections (number / mm ² ). Such a number density is calculated everywhere at several positions (for example, five positions), and the number of the obtained number density is averaged to the average number density D ₂ .

The polishing pad 10 has an average number density D _{1 of} from 1,000 to 5,000 / mm ² , preferably from 1,000 to 4,500 / mm ² , further preferably from 1,100 to 4,000 / mm ² , particularly preferably from 1,200 to 3,000 / mm ² range. When D _{1 is} less than 1000/mm ² , the rigidity in the vicinity of the surface of the polishing surface 3 is lowered, and the polishing rate is lowered or the abrasion resistance is lowered due to difficulty in inserting the abrasive grains into the substrate to be polished. reduce. Further, when D ₁ exceeds 5,000/mm ² , since the rigidity near the surface of the polishing surface 3 is excessively high, scratching easily occurs.

Further, the polishing pad 10 has an average number density D _{2 of} from 200 to 3,500 / mm ² , more preferably from 300 to 3,000 / mm ² , particularly preferably from 500 to 2,500 / mm ² . When D _{2 is} too low, the followability or suitability of the substrate to be polished is too high and the rigidity of the entire polishing pad is lowered, so that the flattening performance tends to be lowered. Here, the flattening property means the ability to form a polished surface having a high flatness on a substrate to be polished. When the average number density D _{2 is} too high, the followability to the substrate to be polished or the suitability is lowered, and the polishing unevenness in the polishing surface tends to be high. Further, since the retention of the polishing paste inside the polishing pad is lowered, the polishing rate tends to be lowered.

The polishing pad 10 has a ratio (D ₁ /D ₂ ) of its average number density D _{1 to} its average number density D ₂ of from 1.3 to 5, preferably from 1.4 to 3.7, further preferably from 1.5 to 2.6. In the case where D ₁ /D _{2 is} less than 1.3, the polishing rate will be increased due to the increase in rigidity; however, since the followability to the substrate to be polished becomes too low, the polishing unevenness will become high while being resistant to abrasion. Sex will also decrease. On the other hand, when D ₁ /D ₂ exceeds 5, since the followability to the substrate to be polished becomes too high, the polishing rate is lowered, and the polishing surface 3 side and the fixing surface 4 of the polishing pad are The difference in density on the side is too large, and the followability between the side of the polishing surface 3 and the side of the fixing surface 4 is different to lower the flattening performance.

Further, the polishing pad 10 has an average number density D ₁ , an average number density D ₂ , and an average number density of fiber bundle cross sections in the thickness region R ₃ from the surface of the polishing surface 3 to the thickness direction of 40 to 60%. D _{3 is} preferably a relationship of D ₁ > D ₃ > D ₂ . In the case of such a relationship, since the polishing paste inside the polishing pad 1 has excellent retentivity, a higher polishing rate is achieved. In addition, the rigidity of the polishing pad and the followability to the substrate to be polished also have excellent balance. As a result, the flattening performance or the polishing rate becomes higher, and the abrasion resistance tends to become higher.

Further, in the case where D ₁ /D ₃ is in the range of 1 to 1.4, the rigidity balance inside the nonwoven fabric becomes more appropriate, and the penetration hardness to the substrate to be polished of the abrasive grains becomes high, and the polishing can be obtained with high polishing. The tendency of speed. Further, from the viewpoint of more suitable for the followability of the substrate to be polished, D ₃ /D _{2 is} preferably in the range of 1.4 to 3.

The ultrafine fibers forming the fiber bundle have an average cross-sectional area of 0.1 to 30 μm ² , preferably 10 to 15 μm ² . In the case of a fiber bundle composed of ultrafine fibers having an average cross-sectional area of less than 1 μm ² , the fibers are broken and peeled off during polishing, and the abrasive particles are condensed on the detached fibers to cause scratches to easily occur. . Further, in the case of a fiber bundle composed of ultrafine fibers having an average cross-sectional area of more than 30 μm ² , the surface area of the ultrafine fibers is increased, and it is difficult to sufficiently increase the density of the fiber bundles in the vicinity of the polished surface.

Further, the fiber bundle has an average cross-sectional area of 40 to 400 μm ² , and more preferably 40 to 350 μm ² . When the average cross-sectional area of the fiber bundle is 40 μm ² or more, the strength or abrasion resistance of the polishing pad is improved, and it is also difficult to cause fiber breakage due to the needle sticking treatment at the time of nonwoven fabric production. Further, when the average cross-sectional area of the fiber bundle is 400 μm ² or less, the polishing rate can be further increased because the density of the fiber bundle in the vicinity of the polished surface can be sufficiently increased. Further, the number of the ultrafine fibers forming a fiber bundle is preferably from 5 to 4,000, more preferably from 5 to 30.

The polymer forming the ultrafine fibers is not particularly limited. Specific examples include, for example, polyethylene terephthalate (PET), isophthalic acid modified PET, sulfoisophthalic acid modified PET, polybutylene terephthalate, and polyparaphenylene. Aromatic polyesters such as hexamethylene dicarboxylate and copolymers thereof; polylactic acid, polyethylene succinate, polybutyl succinate, polybutylene succinate, polyhydroxy butyl Aliphatic polyesters such as ester-polyhydroxyvalerate copolymers and copolymers thereof; polybenzazoles of nylon 6, nylon 66, nylon 10, nylon 11, nylon 12, nylon 6-12, etc. Amines and copolymers thereof; polyolefins and copolymers thereof such as polypropylene, polyethylene, polybutene, polymethylpentene, chlorine-based polyolefin, etc.; modification of ethylene units containing 25 to 70 mol% Polyvinyl alcohol; and an elastomer such as a polyurethane, a nylon or a polyester. These polymers can be used singly or in combination of two or more.

Further, the polymer-forming glass having a very fine fiber has a glass transition temperature (Tg) of preferably 50 to 300 ° C, more preferably 60 to 150 ° C, and a water absorption ratio of 0.2 to 2 mass % when saturated with water at 50 ° C. The polymer is particularly desirable.

When the glass transition temperature is in the above range, the flatness of the polishing pad is further increased because the rigidity can be maintained higher, and the rigidity is less likely to be lowered as time passes. Further, in the case where the water absorption at the time of saturated water absorption at 50 ° C is in the above range, since the polishing pad absorbs the polishing paste in an appropriate range, the polishing rate or the polishing uniformity is further improved. In addition, since the polishing paste is not excessively absorbed, the rigidity of the polishing pad is lowered with time and the variation of the flattening performance with time is suppressed.

Specific examples of such a polymer include, for example, PET (Tg 77 ° C, water absorption: 1% by mass), isophthalic acid-modified PET (Tg 67 to 77 ° C, water absorption: 1% by mass), and sulfo group. Isophthalic acid modified PET (Tg 67 to 77 ° C, water absorption 1 to 3 mass%), polybutylene naphthalate (Tg 85 ° C, water absorption 1% by mass), polyethylene naphthalate ( Aromatic polyester fiber formed by Tg 124° C., water absorption rate: 1% by mass; etc.; copolymerization of polydecylamine from isophthalic acid and decanediol and methyl octanediol (Tg 125 to 140° C., water absorption rate) A semi-aromatic polyamide fiber formed by the like, such as 1 to 3 mass%). In particular, a semi-aromatic polyester-based polymer such as PET or the like which contains an aromatic component as a monomer unit of one component or a modified PET is particularly preferable. When a semi-aromatic polyester-based polymer is used, it is particularly preferable from the viewpoint that it is easy to increase the rigidity of the polishing sheet, and it is less likely to change with time due to moisture during polishing, and it is easy to form a dense one. And high density is not woven.

Further, the nonwoven fabric in the present embodiment is formed of a fiber bundle of ultrafine fibers, and the long fiber web of the ultrafine fiber-derived ultrafine fiber-generating fiber has excellent form stability, and further It is also preferable from the viewpoint that the fiber shedding is reduced. For example, such a non-woven fabric is manufactured by a so-called spinning adhesive which is directly bonded to melt-spun yarn, and a long-fiber cotton web composed of a very fine fiber-generating fiber such as an island-in-sea type composite fiber is produced, and the long-fiber cotton web is wound and processed. After the winding of the cotton web, the ultrafine fiber-forming fibers are converted into ultrafine fibers. Further, the term "long fiber" is not a staple which is intentionally cut by a fiber length of about 10 to 50 mm short fibers, and a fiber having a long fiber length. Specifically, for example, the fiber length of the ultrafine fiber-generating fiber is preferably 100 mm or more, and may be a fiber length of several m, several hundred m, or several km as long as it is technically manufacturable and does not physically break.

Further, the nonwoven fabric in the present embodiment may be a nonwoven fabric in which the knitted fabric is wound and integrated for the purpose of improving the form stability. Further, in the case of using a woven non-woven fabric, the average number density of the fiber bundles is calculated based on the thickness of only the non-woven fabric other than the woven fabric.

The polishing pad 10 has a structure in which the polymer elastic body 2 is applied to the inside of the nonwoven fabric 1 formed of the fiber bundle 1b of the ultrafine fibers 1a, and is composited.

The content ratio of the nonwoven fabric 1 to the polymeric elastomer 2 (non-woven fabric/polymer elastomer; mass ratio) is preferably from 55/45 to 95/5, further preferably from 60/40 to 90/10, particularly preferably 70/. 30 to 90/10 range. In the case of such a range, a polishing pad having a moderate rigidity can be obtained. When the content ratio of the polymeric elastomer is too small, the rigidity of the polishing pad tends to be too low. Further, when the content ratio of the polymeric elastomer is too large, the rigidity of the polishing pad tends to be too high.

Further, as shown in Fig. 2, in the polishing pad 10, the ultrafine fibers 1a forming the fiber bundle 1b are preferably bundled by the polymer elastic body 2 to be bundled. Here, the bundling of the ultrafine fibers 1a means that most of the ultrafine fibers 1a existing inside the fiber bundle 1b are bonded by the polymer elastic body 2 penetrating into the inside of the fiber bundle 1b. In this manner, by bundling the ultrafine fibers 1a, the rigidity of the polishing pad 10 becomes high, and the peeling of the ultrafine fibers 1a is also suppressed. When the ultrafine fibers 1a are not bundled, the polishing fibers tend to be soft due to the oscillation of the ultrafine fibers.

Further, as shown in Fig. 2, the plurality of fiber bundles 1b are preferably present in a bulk by being bonded to the polymer elastic body 2 existing on the outer side of the fiber bundle 1b. In this manner, by maintaining the fiber bundles bonded to each other, the shape stability of the polishing pad is improved and the polishing stability is improved. Further, the state in which the ultrafine fibers are bundled and the state in which the fiber bundles are bonded to each other can be confirmed by an electron micrograph of the cross section of the polishing pad.

The polymer elastomer in which the polymer elastomer and the ultrafine fiber bundle which are infiltrated into the inside of the ultrafine fibers are preferably non-porous. In addition, the term "non-porous" means a state in which a plurality of independent bubbles of a polymer elastomer having a porous shape or a sponge shape (hereinafter, also referred to simply as a porous shape) are not substantially provided. Specifically, for example, it means a polymer elastomer having many fine closed cells which are not obtained by solidifying a solvent-based polyurethane. When the polymer elastic body to be bundled or bonded is non-porous, the polishing stability is increased, and since the paste or the swarf during polishing is less likely to accumulate in the void, it is less likely to be worn and long. The time maintains a high polishing rate. Further, since the bonding strength to the ultrafine fibers is increased, the occurrence of scratches due to the falling off of the fibers can be further suppressed. Furthermore, since a higher rigidity can be obtained, a polishing pad having more excellent planarization performance can be obtained.

The D hardness of the polishing surface 3 of the polishing pad 10 is preferably from 25 to 50, further preferably from 30 to 49, particularly preferably from 31 to 47. When the D hardness is in such a range, it is hard to be affected by the surface shape of the substrate to be polished, and a polishing pad having an optimum rigidity can be obtained from the viewpoint of planarization performance.

Next, the polymer elastic body provided inside the nonwoven fabric will be described in detail.

The type of the polymer elastomer to be imparted inside the nonwoven fabric is not particularly limited. Specific examples of the polymer elastomer include, for example, a polyurethane resin, a polyamide resin, a (meth)acrylate resin, a (meth)acrylate-styrene resin, or a (meth) group. Acrylate-acrylonitrile-based resin, (meth)acrylate-olefin resin, (meth)acrylate-(hydrogenated) isoprene resin, (meth)acrylate-butadiene resin, Styrene-butadiene resin, styrene-hydrogen isoprene resin, acrylonitrile-butadiene resin, acrylonitrile-butadiene-styrene resin, vinyl acetate resin, (methyl An elastomer composed of an acrylate-vinyl acetate resin, an ethylene-vinyl acetate resin, an ethylene-olefin resin, a siloxane resin, a fluorine resin, or a polyester resin. The polymeric elastomers may be used singly or in combination of two or more. Among these polymer elastomers, a hydrogen-bonding polymer elastomer such as a polyurethane resin, a polyamide resin, or a polyvinyl alcohol resin is particularly preferable. Further, the polymer elastic body in which the hydrogen-bonded polymer elastic system is crystallized or agglomerated by hydrogen bonding has high binding property to the ultrafine fibers and high binding strength to the ultrafine fibers. Further, the polyurethane resin is used to bundle extremely fine fibers or bonded fiber bundles with particularly excellent adhesion, and from the viewpoint of improving the hardness of the polishing pad and having excellent stability over time. It is especially ideal.

The glass transition temperature of the polymeric elastomer is preferably -10 ° C or lower, more preferably -15 ° C or lower. When the glass transition temperature is too high, the polymer elastomer is weak, and it is feared that it will fall off during polishing. The glass transition temperature is calculated from the peak temperature of the loss elastic modulus measured by the dynamic viscoelasticity tensile mode. The glass transition temperature depends on the peak temperature of the α-dispersion of the polymeric elastomer. For example, in the case of a polyurethane resin, the glass transition temperature can be made -10 ° C or lower by adjusting the composition of the polyester which is a soft component or the ratio of the hard component to the soft component.

Further, the polymeric elastomer preferably has the following elasticity. The storage elastic modulus (G') of the polymeric elastomer at 23 ° C and 50 ° C is 90 to 900 MPa, and more preferably 20 to 800, from the viewpoint that the rigidity of the polishing pad becomes high and the elasticity is excellent. MPa. In addition, from the viewpoint of excellent polishing stability, the ratio of the storage elastic modulus (G ₂₃ ') at ₂₃ ° C to the storage elastic modulus (G ₅₀ ') at 50 ° C (G ₂₃ '/G ₅₀ ') It is 4 or less, and further preferably 3 or less and 1/3 or more.

Further, from the viewpoint of having excellent liquid retention properties and polishing stability of the polishing paste, the water absorption rate of the polymer elastic system at 50 ° C for saturated water absorption is preferably from 0.2 to 5% by mass, further preferably from 0.5 to 3 by mass. %.

Here, a representative example of the polymeric elastomer is described in detail with respect to the polyurethane resin. Examples of the polyurethane resin include various polyurethane resins obtained by reacting a polymer polyol, an organic polyisocyanate, a chain extender, and the like with a predetermined molar ratio.

Specific examples of the polymer polyol include, for example, polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and poly(methyltetramethylene glycol), and copolymerization thereof. Polybutylene adipate diol, polybutylene terephthalate diol, polyhexamethylene dicarboxylate diol, poly(3-methyl-1,5-exopentyl Diester)diol, poly(3-methyl-1,5-exopentyl sebacate) diol, isophthalic acid copolymerized polyol, terephthalic acid copolymerized polyol, cyclohexanol Copolymerized polyester-based polyalcohols such as polyalcohols, polycaprolactone diols, and the like; polyhexamethylene carbonate diol, poly(3-methyl-1,5-exopentyl carbonate) Glycol, polypentamethylene carbonate diol, polytetramethylene carbonate diol, poly(methyl-1,8-octamethylene carbonate) diol, poly-n-methylene carbonate A polycarbonate-based polyalcohol or a copolymer thereof such as an alcohol or a polycyclohexane carbonate; a polyester carbonate polyalcohol or the like. Further, if necessary, a polyfunctional alcohol such as a trifunctional alcohol such as trimethylolpropane or a tetrafunctional alcohol such as pentaerythritol may be used in combination, or ethylene glycol, propylene glycol, 1,4-butanediol, or 1,6- may be used in combination. Short-chain alcohols such as hexanediol.

In addition, a polyol component having a hydrophilic group such as a carboxyl group, a sulfonic acid group, a hydrocarbon group, or a carbon number of 5 or less, particularly a carbon number of 3 or less, is contained as a resin structural unit, and can be contained. The dispersibility to the aqueous medium or the wettability to the polishing paste is improved.

Specific examples of the polyol component having a carboxyl group include 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butyric acid, and 2,2-bis(hydroxymethyl)pentane. a diol containing a carboxyl group such as an acid. Further, specific examples of the polyalcohol component having a polyalkylene glycol group having 5 or less carbon atoms include polyethylene glycol, polypropylene glycol, and copolymers thereof.

Further, the polycarbonate component is a polycarbonate-based polyol having a glass transition temperature of -10 ° C or lower and further having a glass transition temperature of -20 ° C or lower, and the glass transition temperature of the polyurethane resin is -10 ° C or lower. In addition, it is particularly desirable because it is easy to increase the modulus of elasticity. The polyalcohol component is preferably a polycarbonate-based polyalcohol containing an alicyclic polycarbonate-based polyalcohol or a linear polycarbonate-based polyalcohol, and particularly preferably contains 60 parts of the total amount of the polyalcohol component. 100% by mass of the amorphous polycarbonate-based polyalcohol having a melting point of 0 ° C or less. From the viewpoint of high cut resistance, water absorption, and storage elastic modulus, a polyurethane resin having such a polycarbonate-based polyalcohol as a raw material is preferred.

Specific examples of the amorphous polycarbonate-based polyalcohol having a melting point of 0 ° C or lower include, for example, poly(3-methyl-1,5-exopentyl carbonate) diol and poly(methyl-1). Branched polycarbonate polyol such as 8-octamethyl carbonate) diol; polyhexamethylene carbonate diol, polypentamethylene carbonate diol, polytetramethylene carbonate A polycarbonate-based polyalcohol such as an ester diol, a polyhexamethylene carbonate diol or a polycyclohexane carbonate.

The polyhydric alcohol component may be used singly or in combination of two or more.

From the viewpoint of suppressing the occurrence of scratches by imparting moderate elasticity, the content ratio of the structural unit derived from the polyol component in the polyurethane resin is preferably from 30 to 65 mass%, further preferably from 40 to 60% by mass, particularly preferably 45 to 55% by mass.

In addition, the polyurethane resin containing a structural unit derived from a polyol component having a hydrophilic group improves the wettability of the polishing paste, but tends to have an excessively high water absorption rate. In order to obtain a polyurethane resin having a water absorption ratio of from 0.2 to 5% by mass in the above-mentioned saturated water absorption at 50 ° C, it is preferred to make the copolymerization ratio of the polyol component having a hydrophilic group from 0.1 to 10 The mass % is further preferably from 0.5 to 5% by mass. When the polyol component having a hydrophilic group is contained as a structural unit in such a content ratio, it is possible to suppress the swelling and softening due to water absorption to the minimum while improving the water absorption rate or the wettability. Further, in order to suppress the water absorption rate from becoming excessively high, it is preferably used in combination with a polyol component having low water absorbability. Specific examples of such a polyhydric alcohol include polycarbonate polyalcohols obtained by copolymerizing the following polycarbonate-based polyols: poly(butyl phthalate diol), poly(3-methyl-1, Polyester-based polyalcohols such as 5-extended pentyl adipate diol, poly(3-methyl-1,5-exopentenyl sebacate) diol, and the like; poly(3- Methyl-1,5-exopentyl carbonate) diol, poly(methyl-1,8-octamethylene carbonate) diol, polyhexamethylene carbonate diol, polypentamethylene Carbonate diol, polytetramethylene carbonate diol, poly nin methylene carbonate diol, polycyclohexane carbonate diol, and the like.

Specific examples of the organic polyisocyanate include aliphatic or alicyclic groups such as hexamethylene diisocyanate, isophorone diisocyanate, norbornane diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate. Non-yellowing diisocyanate such as diisocyanate; 2,4-tolyl diisocyanate, 2,6-tolyl diisocyanate, 4,4'-diphenylmethane diisocyanate, xylene diisocyanate polyurethane, etc. Aromatic diisocyanate or the like. Further, if necessary, a polyfunctional isocyanate such as a trifunctional isocyanate or a tetrafunctional isocyanate may be used in combination. These isocyanates may be used singly or in combination of two or more. From the viewpoint of high adhesion to the ultrafine fibers and an increase in the bridging force of the ultrafine fibers, and a polishing pad having a high hardness can be obtained, among these isocyanates, 4,4'-dicyclohexylmethane diisocyanate and 2 are preferable. An alicyclic diisocyanate or an aromatic diisocyanate such as 4-tolyl diisocyanate, 2,6-tolyl diisocyanate, 4,4'-diphenylmethane diisocyanate or xylene diisocyanate.

Specific examples of the chain extender include, for example, anthracene, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylenediamine, isophoronediamine, piperidine, and a derivative thereof, a diamine such as diammonium adipate or dioxonium isophthalate; a triamine such as diethylenetriamine; a tetraamine such as triethylenetetramine; ethylene glycol or propylene glycol; a diol such as 1,4-butanediol, 1,6-hexanediol, 1,4-bis(β-hydroxyethoxy)benzene or 1,4-cyclohexanediol; trimethylol a triol such as propane; a pentaol such as pentaerythritol; an amine alcohol such as an amine ethyl alcohol or an aminopropyl alcohol; and the like. These chain extenders may be used singly or in combination of two or more. From the viewpoint of high adhesion to fibers and, in addition, a polishing pad having a suitable hardness can be obtained. Among these chain extenders, preferred are hydrazine, piperidine, hexamethylenediamine, isophoronediamine. Two or more kinds of triamines such as a derivative thereof and diethylenetriamine are used in combination. Further, together with the chain extender, a monoamine such as ethylamine, propylamine or butylamine; a monoamine compound having a carboxyl group such as 4-aminobutyric acid or 6-aminohexanoic acid; methanol or ethanol; Monools such as propanol and butanol. Further, a carboxyl group-containing diol such as 2,2-bis(hydroxymethyl)propionic acid, 2,2-bis(hydroxymethyl)butyric acid or 2,2-bis(hydroxymethyl)pentanoic acid is used in combination. In addition, an ionic group such as a carboxyl group can be introduced into the skeleton of the polyurethane elastomer to further improve the wettability to water.

The polyurethane resin is used to control the water absorption rate or the storage elastic modulus, and it is preferred to carry out a reaction by adding two or more functional groups which can be combined with the monomer unit forming the polyurethane. A functional crosslinker or a self-crosslinkable compound such as a polyisocyanate compound or a polyfunctional block isocyanate compound forms a crosslinked structure. The combination of the functional group of the monomer unit and the functional group of the crosslinking agent may be exemplified by a carboxyl group and An oxazoline group, a carboxyl group and a carbodiimide group, a carboxyl group and an epoxy group, a carboxyl group and a cyclic carbonate group, a carboxyl group and an aziridine group, a carboxyl group, an anthracene derivative or an anthracene derivative. From the viewpoint that the crosslinking is formed easily and the rigidity or abrasion resistance of the obtained polishing pad is excellent, among these combinations, it is particularly preferable that the monomer unit having a carboxyl group has a combination of an oxazoline group, a carbodiimide group or an epoxy group crosslinking agent; a combination of a monomer unit having a hydroxyl group or an amine group and a crosslinking agent having a blocked isocyanate group; and a monomer unit having a carboxyl group Combination with an anthracene derivative or an anthracene derivative. For example, a water-dispersible carbon dioxide such as "Carbodilite E-01", "Carbodilite E-02", or "Carbodilite V-02" manufactured by Nisshinbo Co., Ltd. can be used as the crosslinking agent having a carbodiimide group. Imine compound. In addition, with Examples of the oxazoline-based crosslinking agent include water dispersion such as "Epocross K-2010E", "Epocross K-2020E", and "Epocross WS-500" manufactured by Nippon Shokubai Co., Ltd. An oxazoline compound. The active ingredient of the crosslinking agent is preferably from 1 to 20% by mass based on the polyurethane resin. More preferably, it is 1.5 to 10% by mass.

The polyurethane resin may further contain a penetrating agent, an antifoaming agent, a lubricant, a water repellent, an oil repellent, a tackifier, a bulking agent, and a hardening promotion, within a range not impairing the effects of the present invention. A water-soluble polymer compound such as a solvent, an antioxidant, an ultraviolet absorber, an antifungal agent, a foaming agent, polyvinyl alcohol or carboxymethyl cellulose, a dye, a pigment, an inorganic fine particle or the like.

Next, an example of a method of manufacturing the polishing pad of the present embodiment will be described in detail.

(1) Cotton web manufacturing steps

In the present production method, a long-fiber cotton web composed of a sea-island type composite fiber obtained by melt-spinning a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin is first produced. In addition, in the present embodiment, the sea-island type composite fiber is used as a composite fiber for forming an ultrafine fiber, and a conventional ultrafine fiber-generating fiber such as a multilayer laminated fiber may be used instead of the sea-island type composite fiber.

The sea-island type composite fiber is obtained by melt-spinning a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin having low compatibility with a water-soluble thermoplastic resin, and then combining them. Then, the ultrafine fibers are formed by dissolving or decomposing and removing the water-soluble thermoplastic resin from such island-in-sea type composite fibers. From the industrial point of view, the width of the sea-island type composite fiber is preferably from 0.5 to 3 dtex, more preferably from 0.8 to 2.5 dtex.

The water-soluble thermoplastic resin is a polymer which is dissolved or removed by decomposition in an aqueous solution such as water or an aqueous alkali solution or an aqueous acid solution under heating or under a pressurized condition. Specific examples of the water-soluble thermoplastic resin include, for example, polyvinyl alcohol (PVA), a PVA-based copolymer, a copolymerized polyoxyethylene polyethylene glycol, and/or a compound containing a sulfonic acid alkali metal salt. Polyester, etc. Among these water-soluble thermoplastic resins, PVA or PVA-based copolymers are preferred from the viewpoint of having excellent solubility in water.

Further, the water-insoluble thermoplastic resin is used for forming various polymers of the above-mentioned ultrafine fibers, and can be used without particular limitation. Further, the water-insoluble thermoplastic resin may contain various additives. Specific examples of the additive include a catalyst, a coloring preventive agent, a heat resistant agent, a flame retardant, a lubricant, an antifouling agent, a fluorescent whitening agent, a deodorant, a coloring agent, a gloss improving agent, a static eliminating agent, and an antibacterial agent. , anti-caries agents, inorganic particles, etc.

The method of forming a long-fiber cotton web by the spunbonding method by the melt-spinning water-soluble thermoplastic resin and the water-insoluble thermoplastic resin is hereinafter described in detail.

First, the water-soluble thermoplastic resin and the water-insoluble thermoplastic resin are melt-kneaded by the respective extrusion agents, and the yarn bundle of the molten resin is simultaneously discharged from the different spinning nozzles. Then, the discharged yarn bundles are combined by a composite nozzle, and then ejected from the nozzle holes of the spinning head to form island-in-sea type composite fibers. The number of islands in the sea-island type composite fiber is preferably from 5 to 4,000 islands/fiber, and more preferably from 10 to 1,000 islands/fiber, from the viewpoint of easily reducing the cross-sectional area of the single fiber and obtaining a fiber bundle having a high fiber density.

After the sea-island type composite fiber is cooled by a cooling device, it is stretched by means of an air suction device such as an air jet/nozzle by means of a high-speed air flow having a pulling speed of 1000 to 6000 m/min. . Thereafter, a long fiber web is formed by depositing the drawn composite fibers on a movable collecting surface. Also, at this time, if necessary, the long fiber web which is deposited may be partially pressed. From the industrial point of view, the basis weight (mass per unit area) of the long-fiber cotton web is preferably in the range of 20 to 500 g/m ² .

(2) Cotton web winding step

Next, a cotton web winding step of forming a wound web by overlapping a plurality of long fiber webs obtained by winding a plurality of sheets will be described. The wound cotton web is obtained by a conventional nonwoven fabric manufacturing method such as needle sticking or high-pressure water flow treatment by winding a long-fiber web.

First, a phthalic acid-based oil or a mineral oil-based oil which prevents a needle breakage oil, an antistatic oil agent, a entanglement-improving oil agent, or the like is applied to a long-fiber web. Further, in order to reduce the basis weight unevenness, it is also possible to laminate two or more fiber webs by the cross-cladding material and to provide an oil agent. Thereafter, a winding process of winding the fibers three-dimensionally is performed by needle sticking. By winding the needle, it is possible to obtain a wound web which has a high fiber density and is difficult to cause the fibers to fall off. In the needle sticking, by changing the needle-forming conditions on the front side and the back side, it is possible to impart a difference in the fiber bundle density between the front side and the back side.

The needle condition such as the type or amount of the oil agent to be needled, the shape of the needle, the depth of the needle, and the number of needles is such that the density of the fiber bundle on the surface side of the polishing surface and the density of the fiber bundle on the back side of the fixed surface become appropriate. The method of density difference is appropriately selected.

The number of hooks of the needle is selected from, for example, 1 to 9 hooks, and the more the needle breakage does not occur, the better. Further, the pinning depth is preferably set to a range in which the appearance of the surface of the cotton web after the needle is not noticeable. Specifically, for example, the following conditions may be mentioned: the initial stage uses a 6 to 9 hook needle to perform a needle sticking process at a depth of 5 to 25 mm, and the latter half uses a 3 to 6 hook needle to make a depth of 0.1 to 15 mm. To concentrate the fibers on the side of the surface. Further, the number of needles is appropriately selected depending on the shape of the needle, the type and amount of the oil, and the like, and specifically, it is preferably about 500 to 5,000 oz/cm ² , and it is preferably relative to the number of ties from the back side. The number of strands from the surface side is treated to be 1.5 to 2 times or more. Further, in comparison with the back side, it is preferable to use a needle having a large number of needles on the surface side, and the shallower the depth of the needle, the better. Further, it is preferable to increase the number of the strands and selectively wind the fibers on the surface side by the hooks of the needles.

In addition, from the viewpoint of obtaining a wound cotton web having a high fiber density, the basis weight of the wound cotton web after needle sticking is preferably 1.2 times or more, more preferably 1.5 times or more, based on the basis weight of the long fiber web before the needle. Way to proceed. The basis weight of the wound cotton web is appropriately selected in accordance with the thickness of the polishing pad to be used, etc., and is preferably in the range of 100 to 1,500 g/m ² from the viewpoint of excellent workability.

Further, from the viewpoint of obtaining a wound web having good form retention, less fiber shedding, and high fiber density, the interlaminar peel strength of the wound web is preferably 2 kg/2.5 cm or more, and further preferably 4 kg/2.5. More than cm. Also, the interlaminar peel strength is the target of the degree of three-dimensional winding. In the case where the interlayer peel strength is too small, the fiber density of the filament wound body is not sufficiently high. Further, the upper limit of the peeling strength between the layers of the entangled nonwoven fabric is not particularly limited, and is preferably about 30 kg/2.5 cm or less from the viewpoint of the winding treatment efficiency.

(3) Wet heat shrinking treatment step

Next, the fiber density and the degree of entanglement of the wound cotton web are increased by shrinking the cotton web by heat and humidity. In addition, in this step, compared with the case of wet heat shrinkage of the wound cotton web containing short fibers, the wet cotton shrinkage of the wrapped cotton web containing long fibers can further shrink the wound cotton web, so that the ultrafine fibers are The fiber density becomes dense. The moist heat shrinkage treatment is preferably carried out by steam heating.

The steam heating condition is preferably in the range of 60 to 130 ° C, the relative humidity is preferably 75% or more, the relative humidity is more preferably 80% or more, and the heat treatment is performed for 60 to 600 seconds. From the viewpoint of being able to shrink the wound web at a high shrinkage ratio, it is preferable to carry out such heating conditions. Further, in the case where the relative humidity is too low, the moisture which is in contact with the fibers is rapidly dried, and the shrinkage tends to be insufficient.

The wet heat shrinkage treatment is such that the area shrinkage ratio of the wound cotton web is preferably 35% or more, and more preferably 40% or more. In this way, the fiber density becomes dense by shrinking it with a high shrinkage ratio. The upper limit of the area shrinkage ratio is not particularly limited, and is preferably about 80% from the viewpoint of the shrinkage limit or the treatment efficiency. Further, the area shrinkage ratio (%) is calculated by the following formula (1): area shrinkage ratio (%) = (area of sheet surface before shrinkage treatment - area of sheet surface after shrinkage treatment) / shrinkage The area of the sheet surface before the treatment × 100 (1).

In this manner, the wound cotton web subjected to the moist heat shrinkage treatment can further increase the fiber density by heating the roll or heating and compressing at a temperature higher than the heat distortion temperature of the sea-island type composite fiber. At this time, by performing heat compression on the front side and the back side by different conditions, the density gradient of the fiber bundle can be formed. The compression conditions by the heating roller include, for example, a roller temperature of 110 to 150 ° C and a roller pressure of 0.05 to 0.4 MPa. The basis weight of the wound web after the shrinkage treatment is preferably 1.2 to 4 times, more preferably 1.5 to 4 times, the basis weight of the wound web before the shrinking treatment.

(4) Polymer elastomer filling step I

It is also possible to adhere the sea-island type composite fiber to the inside of the wound cotton web by applying the polymer elastic body to the inside of the wound cotton web by the ultrafine fiberizing treatment of the sea-island type composite fiber of the wound cotton web which has been subjected to shrinkage treatment. In this manner, by applying the polymeric elastomer to the wound web before the ultrafine fiberizing treatment, the form stability of the wound web can be improved, or the density gradient of the obtained polishing pad fiber bundle can be adjusted.

In this step, the polymer elastomer is impregnated with the wound cotton web after the shrinkage treatment, and the polymer elastomer is solidified to impregnate the polymer elastomer to the inside of the wound cotton web.

In the aqueous liquid of the polymeric elastomer, the component forming the polymeric elastomer is dispersed in the aqueous dispersion of the aqueous medium, and the component forming the polymeric elastomer is dissolved in the aqueous solution of the aqueous medium. The solid content of the aqueous liquid of the polymeric elastomer is preferably 10% by mass or more, and more preferably 15% by mass or more.

Even if the aqueous dispersion of the polymeric elastomer is high in concentration, the viscosity is low, and since it has excellent impregnation permeability, it is easy to highly fill the wound cotton web and has excellent adhesion to the fiber. Therefore, the sea-island type composite fiber can be strongly restrained by the polymer elastic body impregnated in this step, and the apparent density of the polishing pad can be easily increased. Further, since the polymer elastic system obtained by solidifying the aqueous dispersion of the polymeric elastomer has high wettability with water, a polishing pad capable of uniformly and in large amounts retaining abrasive grains can be obtained.

In the aqueous dispersion, suspension and emulsification are included. The polymer elastomer dispersed in the aqueous dispersion preferably has an average particle diameter of about 0.01 to 0.2 μm.

The method of preparing the aqueous dispersion is not particularly limited. For example, in the case of a polyurethane resin, a hydrophilic group having a carboxyl group, a sulfonic acid group, a hydroxyl group, a carbon number of 5 or less, and especially a polyalkylene group having a carbon number of 3 or less is used. The monomer unit is contained as a resin structural unit, and can impart dispersibility to an aqueous medium. The copolymerization ratio of the monomer unit having such a hydrophilic group is preferably from 0.1 to 10% by mass from the viewpoint of suppressing swelling and softening by water absorption to the minimum and improving water absorption or wettability. It is preferably from 0.5 to 5% by mass.

Further, by using a surfactant, particles of the polyurethane resin can be emulsified or suspended in an aqueous medium. Specific examples of the surfactant which can be used for emulsifying or suspending, for example, sodium lauryl sulfate, ammonium lauryl sulfate, sodium polyoxyalkylene lauryl ether acetate, sodium dodecylbenzenesulfonate, An anionic surfactant such as sodium alkyl diphenyl ether disulfonate or sodium dioctyl sulfosuccinate; poly(extended ethoxyethyl phenyl ether), polyoxyethylene octyl phenyl ether, poly A nonionic surfactant such as oxygen-extended ethyl lauryl ether, polyoxyethylene ethyl stearyl ether, polyoxy-extension ethyl-polyoxypropylene block copolymer, or the like. Further, a reactive so-called reactive surfactant can also be used. Further, the thermal gelation property can be imparted to the polyurethane resin by appropriately selecting the cloud point of the surfactant.

The method of impregnating the wound cotton web with the aqueous liquid of the polymeric elastomer may, for example, be a method using a knife coater, a bar coater, or a roll coater, or a method of immersing. Then, the polymer elastomer can be solidified by drying the wound cotton web impregnated with the aqueous polymer elastomer aqueous solution. The drying method may be a method of performing heat treatment in a drying apparatus at 50 to 200 ° C, or a method of performing heat treatment in a dryer after infrared heating. Further, by immersing the aqueous liquid of the polymeric elastomer in the wound cotton web and then drying it, the water will evaporate from the surface layer of the wound cotton web and the aqueous liquid will migrate to the surface layer. It is preferred to form a density gradient of the fiber bundle by drying the polymer elastomer under conditions which promote the migration, and the polymer elastomer is uneven in the surface layer. Specific examples of the heat treatment temperature of the hot air dryer are, for example, preferably 130 to 170 ° C, and more preferably 140 to 170 ° C. By such a method, the density of the side of the polishing surface can be increased not only in accordance with the density difference of the fiber bundle but also the density difference caused by the polymer elastomer, and wear resistance can be obtained by further densifying the side of the polishing surface. A more abrasive pad.

(5) Very fine fiber forming step

The step of forming the ultrafine fibers by removing the water-soluble thermoplastic resin in the sea-island type composite fiber will be described in detail.

The water-soluble thermoplastic resin in the island-in-the-sea composite fiber is dissolved or removed by using water, an alkaline aqueous solution, an acidic aqueous solution or the like.

In this step, the wound cotton web which is first wound around the cotton web or imparted to the polymeric elastomer is immersed in hot water such as water, an alkaline aqueous solution, or an acidic aqueous solution to be subjected to hot water treatment. Further, in order to improve the dissolution efficiency, a roll press treatment, a high-pressure water flow treatment, an ultrasonic treatment, a shower treatment, a stirring treatment, a hydrazine treatment, or the like may be performed as necessary. Further, in order to make the fiber bundle of the fixing surface low in density, it may be treated by a high-speed water flow or a mechanical treatment.

Further, the wet heat shrinkage treatment step (3) is not carried out, and in this step, the shrinkage treatment of the wound cotton web and the extremely fine fiberization of the sea-island type composite fiber may be simultaneously performed. Specific examples of the method of performing the shrinkage treatment and the ultrafine fiber at the same time include, for example, immersing the wound cotton web in hot water at 65 to 90 ° C for 5 to 300 seconds in the first stage, and further, The second stage is carried out in hot water at 85 to 100 ° C for 100 to 600 seconds.

(6) Polymer elastomer filling step II

Next, the ultrafine fibers are bundled, and in order to further bind the ultrafine fiber bundles, the step of imparting the polymeric elastomer will be described. In the ultrafine fiber forming step (5), the sea-island type composite fiber is subjected to an extremely fine fiberizing treatment, whereby the water-soluble thermoplastic resin is removed and a void is formed inside the ultrafine fiber bundle. In this step, the ultrafine fibers are bundled by imparting a polymeric elastomer to such a void. Further, at the same time, the ultrafine fiber bundles are further bound to each other by the polymeric elastomer. Further, in the case where the ultrafine fibers have formed a fiber bundle, the aqueous liquid of the polymeric elastomer is easily absorbed by the inside of the fiber bundle by the capillary phenomenon. Further, the aqueous liquid of the polymeric elastomer used in the present invention may be the same as the aqueous liquid described in the step I of the polymeric elastomer. Further, in the method of filling and solidifying the polymer elastomer, the method described in the same manner as in the step of filling the polymer elastomer may be used. In this manner, the polishing pad precursor will be formed.

(7) Finishing steps

The polishing pad of the present embodiment can be obtained by performing a planarization treatment on the obtained polishing pad precursor. The flattening treatment is a process for adjusting the thickness by thermally compressing the polishing pad precursor to a predetermined thickness and smoothing the surface by grinding the surface with sandpaper, wire cloth, diamond, or the like. In this manner, the thickness of the finished polishing pad is preferably about 0.5 to 3 mm.

In addition, the surface of the polishing pad can also be raised. By performing the raising treatment, the contact area between the polishing surface of the polishing pad and the substrate to be polished becomes large, and the wettability with the polishing paste is improved. The raising process is a method of polishing the surface of the polishing pad using sandpaper. For the sandpaper, sandpaper of #40###80 is used. Specific examples of the raising treatment include, for example, a continuous raising treatment by a contact type polishing machine, or a diamond-type polishing treatment, or a combination contact type and a diamond-type polishing treatment. Further, in order to form a uniform raised state, it is also possible to compress the surface of the polishing pad which is raised.

Further, in order to further improve the flattening performance, surface processing for forming grooves or holes of concentric, spiral, or lattice shape may be performed on the surface of the polishing pad. By performing such surface processing, the polishing paste can be more uniformly filled on the polishing surface.

Next, the chemical mechanical polishing method using the polishing pad of the present embodiment will be described in detail with reference to FIG. 3 . Fig. 3 is a side view showing an embodiment of a chemical mechanical polishing method using the polishing pad 10 of the present embodiment.

In the chemical mechanical polishing method using the polishing pad 10 of the present embodiment, for example, a CMP device having a circular rotary fixed disk 11 as shown in FIG. 3, a paste supply nozzle 12, a carrier 13, and a pad conditioner 14 can be used. 20. On the surface of the rotary fixed disk 11, the fixing surface 4 is attached by means of a double-sided tape to attach the polishing pad 10. Further, the carrier 13 is supported by the polishing substrate 15.

In the CMP apparatus 20, the fixed disk 11 is rotated in the direction indicated by the arrow mark by omitting the motor of the drawing. Further, the carrier 13 is placed in the plane of the fixed disk 11, and is rotated in a direction indicated by, for example, an arrow mark by a motor in which the drawing is omitted. The pad conditioner 14 is also rotated in the direction indicated by the arrow mark by the motor omitting the motor in the plane of the fixed disk 11.

First, while the distilled water flows onto the surface of the polishing pad 10 that is fixed by the rotation of the rotating fixed disk 11, the pad conditioner 14 that is rotated on the surface of the polishing pad 10 is pressed to adjust the surface of the polishing pad 10. Next, the polishing paste 16 containing various chemical components and hard fine abrasive grains is supplied from the paste supply nozzle 12 to the surface of the polishing pad 10 to be rotated. Then, on the polishing pad 10 which is filled around the polishing paste 16, the substrate 15 to be polished which is fixed by the carrier 13 and rotated is pressed. Then, the grinding process is continued until a predetermined flatness can be obtained. The finishing quality is affected by adjusting the pressing force applied to the grinding or by rotating the relative movement speed of the fixed disk 11 and the carrier 13.

In the chemical mechanical polishing method of the present embodiment, the polishing pad 10 is attached to the surface of the rotating fixed disk 11 and fixed by the fixing surface 4. By fixing the polishing pad 10 by the fixing surface 4, since the number of the fiber bundles is high and the polishing surface 3 having high rigidity becomes the outer surface, the polishing rate and the abrasion resistance are increased, and the polishing in the polishing surface is uneven. Sex will become lower. Further, since the surface layer fiber bundle on the side of the fixing surface 4 fixed to the rotating fixed disk 11 has a low number density and low rigidity, it is possible to maintain appropriate followability or suitability for the surface of the substrate 15 to be polished.

The components of the polishing paste 16 are appropriately selected depending on the type of the substrate 15 to be polished. Specific examples of the abrasive grains include, for example, SiO ₂ , Al ₂ O ₃ , CeO ₂ , Mn ₂ O ₃ , diamond particles having a particle diameter of several tens nm to several hundreds nm. Further, specific examples of the chemical component include, for example, a component of a surface to be polished such as a modified acid/base or a surfactant.

The chemical mechanical polishing method of this embodiment can be used for polishing various substrates. Specific examples of the substrate include, for example, an insulating material such as ruthenium, osmium oxide, yttrium oxyfluoride or an organic polymer; conductive materials such as copper, aluminum, and tungsten; tantalum, titanium, tantalum nitride, and titanium nitride; Waiting for barrier materials, etc. Moreover, specific examples of the use thereof include a germanium wafer, a compound semiconductor wafer, a semiconductor wafer, a semiconductor element, a liquid crystal member, an optical element, a crystal, an optical substrate, an electronic circuit board, and an electronic circuit mask substrate. Grinding of multilayer wiring boards, hard disks, MEMS (Micro Electro Mechanical Systems) substrates, and the like. Further, the polishing may be any one of primary polishing, secondary polishing (adjustment polishing), finishing polishing, mirror polishing, and the like.

Example

Hereinafter, embodiments will be specifically described by way of examples. Further, the scope of the present invention is not limited by the description of the embodiments.

First, the evaluation method used in the present embodiment will be described.

[evaluation method]

(1) Determination of the average number density (D ₁ , D ₂ , D ₃ ) of the ultrafine fiber bundles, the average cross-sectional area of the single fibers, and the average cross-sectional area of the fiber bundles

The polishing pad is cut parallel to the thickness direction by using the blade of the cutter to form a cross section in the thickness direction. Then, the obtained cross section is dyed with yttrium oxide. The cross section was observed by a scanning electron microscope (SEM) at 100 to 1000 times, and an image was taken. Then, the cross-sectional area of the selected 100 ultrafine fiber bundles was arbitrarily determined from the obtained image, and the average value thereof was defined as the average cross-sectional area of the ultrafine fiber bundle. Further, the cross-sectional area of the 100 ultrafine fibers forming the ultrafine fiber bundle was determined, and the average value thereof was defined as the average cross-sectional area of the single fibers of the ultrafine fibers.

Further, from the obtained image, a 0.1 mm square region of five positions was selected from the surface of the polishing pad in the thickness direction of 20% in the thickness direction, and the number of the ultrafine fiber bundles at each position was calculated. From the results, the number of fine fiber bundles present per 1 mm ^{2 was} calculated. The average of the five positions is set to D ₁ .

Further, from the obtained image, a 0.1 mm square region of five positions was selected from the back surface of the polishing pad in the thickness direction of 20% in the thickness direction, and the number of the ultrafine fiber bundles at each position was calculated. From the results, the number of fine fiber bundles present per 1 mm ^{2 was} calculated. The average of the five positions is set to D ₂ .

Further, from the obtained image, a 0.1 mm square region of five positions was selected from the surface of the polishing pad in the vicinity of 50% in the thickness direction, and the number of the ultrafine fiber bundles at each position was calculated. From the results, the number of fine fiber bundles present per 1 mm ^{2 was} calculated. The average of the five positions is set to D ₃ .

(2) Interlaminar peel strength of wound cotton web

A test piece of a rectangular length of 23 cm and a width of 2.5 cm was prepared from the obtained wound cotton web. Then, at one end of the test piece, the scribe was drawn into the approximate center of the thickness direction by a razor. Then, it was peeled off by hand stretching about 10 cm from the edge. Then, the two peeled edges were fixed to the chucks of the respective tensile testers. Then, it was stretched by a tensile tester to obtain a stress-skew curve (SS curve), and the peeling strength was obtained from the stress of the flat portion. Also, the stretching speed was performed at 100 mm/min. Also, the results obtained are the average of 3 test pieces.

(3) Method for measuring D hardness of polishing pad

The D hardness of the polishing surface of the polishing pad was measured in accordance with JIS K 6253 using a hardness meter D type (manufactured by Kobunshi Co., Ltd.). Also, the load system is set to 5 kg.

(4) Wear weight reduction

The Taber abrasion of the polishing pad cut into a circular diameter of 13 cm was measured according to the method of JIS K5600-5-9. Further, it was measured under the conditions of a wear wheel: H-22, a load: 500 g, and a number of revolutions: 1,000. The weight loss (mg) of the difference between the weight before measurement and the weight after measurement was determined.

(5) Determination of glass transition temperature (Tg) of polymeric elastomers

A film having a length of 4 cm × a width of 0.5 cm × a thickness of 400 μm ± 100 μm made of a polymeric elastomer constituting a polishing pad was prepared. Then, the thickness of the film was measured by a micrometer, and dynamic viscoelasticity was measured at a frequency of 11 Hz and a temperature increase rate of 3 ° C/min using a dynamic viscoelasticity measuring apparatus (DVE Rheospectoler, manufactured by Rheology Co., Ltd.). The main dispersion peak temperature of the loss elastic modulus is set as the glass transition temperature.

(6) Method for measuring storage elastic modulus of polymeric elastomers at 23 ° C and 50 ° C

The polymer elastomer constituting the polishing pad was made into a film having a length of 4 cm × a width of 0.5 cm × a thickness of 400 μm ± 100 μm. Then, the thickness of the film was measured by a micrometer, and then measured at 23 ° C and 50 using a dynamic viscoelasticity measuring apparatus (DVE Rheospectoler, manufactured by Rheology Co., Ltd.) at a frequency of 11 Hz and a temperature increase rate of 3 ° C/min. The storage elastic modulus of °C is calculated, and the storage elastic modulus is calculated.

(7) Method for measuring saturated water absorption of polymer elastomer

A film having a thickness of 200 μm obtained by drying the polymer elastomer constituting the polishing pad at 50 ° C was heat-treated at 130 ° C for 30 minutes. Then, it was allowed to stand at 20 ° C and 65% RH for 3 days. Then, the mass at the time of drying at this time was measured. The dried film was immersed in water at 50 ° C for 2 days. Then, after taking out water of 50 ° C, excess water droplets and the like on the outermost surface of the film were wiped off, and the mass after water absorption was measured. Then, the saturated water absorption rate was calculated by the following formula.

Saturated water absorption (%) = [(mass after water absorption - mass at drying) / mass at dry time] × 100

(8) Grinding performance of the polishing pad

The double-sided adhesive tape was attached to the fixed surface of the polishing pad and fixed to a rotary fixed disk of a CMP polishing apparatus ("PPO-60S" manufactured by Nomura Manufacturing Co., Ltd.). Then, by using a diamond dresser of cotton yarn count #200 (MEC200L manufactured by Mitsubishi Material Co., Ltd.), the flow rate was 120 mL/min under the conditions of a pressure of 177 kPa and a dresser rotation number of 110 rotations/min. The distilled water was conditioned by grinding the surface of the polishing pad for 18 minutes (air drying).

Next, the polishing paste is supplied to the surface of the polishing pad fixed to the rotary fixed disk. In the polishing paste, a polishing paste obtained by diluting a polishing paste SS25 made by Cabot Corporation into two times with distilled water was used. Further, the supply amount of the polishing paste was set to 120 ml/min. Then, 100 seconds of polishing of the 8-inch diameter wafer having the surface of the oxide film was carried out under the conditions of a platen rotation number of 50 rotations/min, a head rotation number of 49 rotations/min, and a polishing pressure of 35 kPa.

Then, the film thickness of the oxide film before and after the polishing at 49 points was measured in the wafer surface, and the polishing rate (nm/min) was determined. Further, the average value of the polishing rate of 49 points was defined as the average polishing rate (R), and the standard deviation (σ) of the polishing rate was further determined. Then, by equation (1):

Heterogeneity (%) = (σ/R) × 100...(1)

And calculate the heterogeneity. The smaller the value of the heterogeneity, the more uniformly the inside of the polished surface is displayed. Moreover, it is possible to achieve high-precision grinding processing.

In addition, by equation (2):

Grinding rate stability (%) = (maximum grinding rate - minimum grinding rate) × 100... (2)

The polishing rate stability was calculated.

Further, the scratch resistance was evaluated by using a wafer surface inspection apparatus Surfscan SP1 (manufactured by KLA-Tencor Co., Ltd.) to measure a scratch of 0.16 μm or more which was present on the surface of the tantalum wafer having the oxide film after polishing.

[Example 1]

A PVA resin as an island component and a modification degree of 6 mol% as a sea component were used as a phthalic acid-modified PET. Further, the isophthalic acid-modified PET had a water absorption ratio of 1% by mass when saturated at 50 ° C and a glass transition temperature of 77 ° C. The PVA resin and the isophthalic acid-modified PET are sprayed at a ratio of 25:75 (mass ratio) from a 25-island/fiber fusion composite spinning nozzle (nozzle temperature: 260 ° C) to form an island-in-sea type composite fiber. Yarn bundle. Then, the yarn bundle ejected from the nozzle is stretched by an air jet pumping device disposed directly under the nozzle, and is stretched and refined, and cooled to be spun, and the island-type composite length of the average fineness of 2.0 dtex is spun. fiber. In addition, the pumping force of the air jet pumping device was adjusted so that the indirect obtained spinning speed became 4000 m/min from the ratio of the discharge amount per unit time and the obtained long fiber fineness. Then, by continuously collecting the sea-island type composite fibers on a mobile net disposed directly below the air jet suction device, a spunbonded web (long fiber web) having a basis weight of 40 g/m ² was obtained.

Next, the spun yarn sheets obtained by superposing 12 sheets by cross-polishing were used to prepare a web laminate having a total basis weight of 480 g/m ² . Then, the obtained cotton mesh laminate is sprayed to prevent the needle from breaking the oil. Next, the cotton mesh layering system sequentially uses needle cotton yarn count No. 42, needle number three needles, and needle cotton yarn count No. 42 and hook number six needles, using needle depth from the first surface side thereof The needle is treated under the condition of a depth of 5 to 25 mm and a number of sheets of 1500 扎/cm ² , and further, with a depth of 0 to 15 mm from the side of the second surface thereof and a number of sheets of 500 扎/cm ² The condition is handled by needle sticking. The area shrinkage of the cotton web laminate due to needle sticking is 30%. By such a needle-punching treatment, a wound web having a basis weight of 600 g/m ² and an interlayer peeling strength of 11.0 kg/2.5 cm can be obtained.

Then, by immersing the obtained wound cotton web in hot water at 70 ° C for 90 seconds, the island component stress is alleviated, so that the area shrinks by 43%, and further immersed in hot water of 95 ° C for 10 minutes to make PVA resin. Dissolved and removed. Further, in the dry state, the area shrinkage of the wound web due to hot water treatment was 45%. A non-woven fabric composed of fiber bundles of ultrafine fibers can be obtained by hot water treatment. The nonwoven fabric has a basis weight of 780 g/m ² and an apparent density of 0.55 g/m ³ .

Then, an aqueous emulsion of the polyurethane elastomer A adjusted to a solid concentration of 25% by mass was impregnated into the obtained nonwoven fabric. Further, the average particle diameter of the polyurethane elastomer A in the aqueous emulsion was 0.05 μm.

Further, the polyurethane elastomer A is a polymer as follows. Polyurethane elastomer A is copolymerized with 1.5% by mass of 4,4'-dicyclohexylmethane diisocyanate and short-chain amine and short-chain diol with respect to 50% by mass of the polymer diol. 100 parts by mass of a polycarbonate-based non-yellowing type polyurethane having a total amount of 2'-bis(hydroxymethyl)propionic acid in a total amount of 50% by mass, and 5 parts by mass of a carbodiimide group A crosslinked polyurethane resin. Further, the polymer diol is a mixture of a non-polymerized polyalcohol of octa methylene carbonate and penta methylene carbonate of an amorphous polycarbonate-based polyalcohol and a carbon at 99.9:0.1 (mole ratio). A mixture of 2 to 3 polyalkylene glycols.

The polyurethane elastomer A has a water absorption ratio of 2% by mass, a storage elastic modulus of 450 MPa at 23 ° C, a storage elastic modulus of 300 MPa at 50 ° C, and a glass transition temperature of -25 ° C. In addition, the aqueous emulsion was impregnated with 15% by mass based on the mass of the nonwoven fabric in terms of the solid content of the polyurethane elastomer A. Next, the coagulation treatment of the nonwoven fabric impregnated with the aqueous emulsion was carried out in a 90° C. or 50% RH gas atmosphere, and further dried at 150° C., and further thermally compressed at 150° C. to obtain a polishing pad precursor A0. The polishing pad precursor A0 had a basis weight of 910 g/m ² , an apparent density of 0.62 g/m ³ , and a thickness of 1.45 mm. Further, the mass ratio of the nonwoven fabric to the polyurethane elastomer A was 87/13.

Then, the polishing pad precursor A1 can be obtained by polishing the polishing pad precursor A0. An electron microscope was used to observe the cross section of the polishing pad A1. The average density D ₁ of the ultrafine fiber bundle was about 2,500 / mm ² , and the average density D ₂ of the ultrafine fiber bundle was about 1,200 / mm ² , D ₁ /D ₂ It is about 2.1. Further, in the cross section thereof, an ultrafine fiber bundle having an average cross-sectional area of about 320 μm ² composed of ultrafine fibers having an average cross-sectional area of about 11 μm ^{2 was} observed. Further, the ultrafine fibers are bundled by the polyurethane elastomer which penetrates into the inside of the ultrafine fiber bundle, and the ultrafine fiber bundles are also adhered to each other by the polyurethane elastomer. The polishing pad A1 had a basis weight of 750 g/m ² , an apparent density of 0.61 g/m ³ , a thickness of 1.23 mm, and a D density of 37.

The obtained polishing pad A1 was cut into a circular shape having a diameter of 51 cm, and further processing for forming a lattice-like groove having a width of 2.0 mm, a depth of 1.0 mm, and a spacing of 15.0 mm was formed on the main surface. The polishing performance of such a polishing pad A1 was evaluated by the above evaluation method. The results are shown in Table 1.

[Embodiment 2]

The steam heating of the wound cotton web obtained in Example 1 was carried out under the conditions of an ambient temperature of 60 ° C, a relative humidity of 80%, and 500 seconds. Then, for the steam-treated wound web, the surface of the wound web was only subjected to compression treatment using a heat roller of 120 °C. In the dry state, the area shrinkage of the wound web by the steam heat treatment and the compression treatment is 40%. Then, an aqueous emulsion of a polyurethane elastomer A having a solid concentration of 15% by mass was impregnated into the wound cotton web after the treatment. Next, the coagulation treatment of the non-woven fabric impregnated with the aqueous emulsion was carried out in a 90 ° C, 50% RH gas atmosphere, and further dried at 150 ° C to form a composite of the wound cotton web and the polyurethane elastomer A ( Wrap the cotton mesh composite). Further, in terms of the solid content of the polyurethane elastomer A, the aqueous emulsion was impregnated with 7 mass% based on the total mass of the wound cotton web composite. Then, the PVA resin is dissolved and removed by immersing the obtained wound cotton web composite in hot water at 95 ° C for 10 minutes, and further, by drying, a nonwoven fabric and a polyamine composed of fiber bundles of ultrafine fibers are formed. A complex of formate elastomer A (nonwoven composite).

Then, the aqueous emulsion of the polyurethane elastomer A adjusted to a solid concentration of 25% by mass was further impregnated into the nonwoven fabric composite. In terms of the solid content of the polyurethane elastomer A, the aqueous emulsion was impregnated with 15% by mass based on the total mass of the nonwoven fabric. Next, the coagulation treatment of the nonwoven fabric impregnated with the aqueous emulsion was carried out in a 90° C. or 50% RH gas atmosphere, and further dried at 150° C., and further heat-compressed at 150° C. to obtain a polishing pad precursor B0. The polishing pad precursor B0 had a basis weight of 730 g/m ² , an apparent density of 0.58 g/m ³ , and a thickness of 1.26 mm. Further, the mass ratio of the nonwoven fabric to the polyurethane elastomer A was 80/20.

Then, by polishing the polishing pad precursor B0 by polishing, the flattened polishing pad B1 can be obtained. An electron microscope was used to observe the cross section of the polishing pad B1. The average density D ₁ of the ultrafine fiber bundle was about 2450 / mm ² , and the average density D ₂ of the ultrafine fiber bundle was about 1260 / mm ² , D ₁ /D ₂ It is about 1.9. In addition, its cross section was observed by the average cross-sectional area of the average cross-sectional area of about 12μm ² ultrafine fiber composed of microfine fiber bundles of about 525μm ^2. Further, the ultrafine fibers are bundled by the polyurethane elastomer penetrating into the inside of the ultrafine fiber bundle, and the polishing pad B1 has a basis weight of 614 g/m ² , an apparent density of 0.58 g/m ³ , and a thickness of 1.06 mm. D hardness 36. Further, the obtained polishing pad B1 was processed and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 3]

The steam heating of the wound cotton web obtained in Example 1 was carried out under the conditions of an ambient temperature of 80 ° C, a relative humidity of 80%, and 500 seconds. Then, for the steam-treated wound web, the surface of the wound web was only subjected to compression treatment using a heat roller of 120 °C. In the dry state, the area shrinkage of the wound web by the steam heat treatment and the compression treatment is 50%. Then, an aqueous emulsion of a polyurethane elastomer A having a solid concentration of 15% by mass was impregnated into the wound cotton web after the treatment. Next, the coagulation treatment of the nonwoven fabric impregnated with the aqueous emulsion was carried out in a 90 ° C, 50% RH gas atmosphere, and further dried at 150 ° C to form a composite of the wound cotton web and the polyurethane elastomer A. Further, in terms of the solid content of the polyurethane elastomer A, the aqueous emulsion was impregnated with 7 mass% based on the total mass of the wound cotton web composite. Then, the PVA resin is dissolved and removed by immersing the wound cotton web composite in hot water at 95 ° C for 10 minutes, and further, by drying, a nonwoven fabric and a polyurethane composed of fiber bundles of ultrafine fibers are formed. A composite of elastomer A.

Then, the aqueous emulsion of the polyurethane elastomer A adjusted to a solid concentration of 25% by mass was further impregnated into the nonwoven fabric composite. In terms of the solid content of the polyurethane elastomer A, the aqueous emulsion was impregnated with 15% by mass based on the total mass of the nonwoven fabric. Next, the solidification treatment of the nonwoven fabric impregnated with the aqueous emulsion was carried out in a 90 ° C, 50% RH gas atmosphere, and further dried at 150 ° C, and further heat-compressed at 150 ° C to obtain a polishing pad precursor C0. The polishing pad precursor C0 has a basis weight of 790 g/m ² , an apparent density of 0.63 g/m ³ , and a thickness of 1.25 mm. Further, the mass ratio of the nonwoven fabric to the polyurethane elastomer A was 80/20.

Then, the polishing pad precursor C1 can be obtained by polishing the polishing pad precursor C0. An electron microscope was used to observe the cross section of the polishing pad C1. The average density D ₁ of the ultrafine fiber bundle was about 2840/mm ² , and the average density D ₂ of the ultrafine fiber bundle was about 1890/mm ² , D ₁ /D ₂ It is about 1.5. In addition, its cross section was observed by the average cross-sectional area of about 13μm average cross sectional area of the ultrafine fiber ² constituted of the ultrafine fiber bundle was about 325μm ^2. Further, the ultrafine fibers are bundled by a polyurethane elastomer penetrating into the inside of the ultrafine fiber bundle, and the polishing pad C1 has a basis weight of 650 g/m ² , an apparent density of 0.63 g/m ³ , and a thickness of 1.03 mm. D hardness 37. Further, the obtained polishing pad C1 was processed and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Example 4]

A 12-piece spunbonded sheet obtained in the same manner as in Example 1 was superposed by cross-polishing to prepare a web laminate having a total basis weight of 480 g/m ² . Then, the needle breaking oil is prevented from being sprayed on the obtained web laminate. Next, the cotton mesh layering system sequentially uses needle cotton yarn count No. 42, needle number one needle, and needle cotton yarn count No. 42 and hook number six needles to have a needle depth of 5 from the first surface side thereof. The needle is treated to a depth of 25 mm and a condition of 1200 扎/cm ² , and the needle is further needled from the second surface side at a depth of the needle depth of 0 to 10 mm and a number of sheets of 300 扎/cm ² . Tie processing. The area shrinkage of the cotton web laminate due to needle sticking is 20%. By such a needle-punching treatment, a wound web having a basis weight of 560 g/m ² and an interlayer peel strength of 9.0 kg/2.5 cm can be obtained.

The steam heating of the obtained wound cotton web was carried out under the conditions of an ambient temperature of 60 ° C, a relative humidity of 70%, and 500 seconds. Then, for the steam-treated wound web, the surface of the wound web was only subjected to compression treatment using a heat roller of 110 °C. In the dry state, the area shrinkage of the wound web by the steam heat treatment and the compression treatment was 35%. Then, an aqueous emulsion of a polyurethane elastomer A having a solid concentration of 15% by mass was impregnated into the wound cotton web after the treatment. Next, the coagulation treatment of the nonwoven fabric impregnated with the aqueous emulsion was carried out in a 90 ° C, 50% RH gas atmosphere, and further dried at 150 ° C to form a composite of the wound cotton web and the polyurethane elastomer A. Further, in terms of the solid content of the polyurethane elastomer A, the aqueous emulsion was impregnated with 7 mass% based on the total mass of the wound cotton web composite. Then, the PVA resin is dissolved and removed by immersing the wound cotton web composite in hot water at 95 ° C for 10 minutes, and further, by drying, a nonwoven fabric and a polyurethane composed of fiber bundles of ultrafine fibers are formed. Non-woven composite of Elastomer A.

Then, the aqueous emulsion of the polyurethane elastomer A adjusted to a solid concentration of 25% by mass was further impregnated into the nonwoven fabric composite. In terms of the solid content of the polyurethane elastomer A, the aqueous emulsion was impregnated with 15% by mass based on the total mass of the nonwoven fabric. Next, the solidification treatment of the nonwoven fabric impregnated with the aqueous emulsion was carried out in a 90 ° C, 50% RH gas atmosphere, and further dried at 150 ° C, and further heat-compressed at 150 ° C to obtain a polishing pad precursor E0. The polishing pad precursor E0 had a basis weight of 665 g/m ² , an apparent density of 0.53 g/m ³ , and a thickness of 1.25 mm. Further, the mass ratio of the nonwoven fabric to the polyurethane elastomer A was 80/20.

Then, by polishing the polishing pad precursor E0, the flattened polishing pad E1 can be obtained. Using an electron microscope to observe the cross section of the polishing pad E1, the average density D ₁ of the ultrafine fiber bundles was about 2,300 / mm ² , and the average density D ₂ of the ultrafine fiber bundles was about 540 / mm ² , D ₁ /D ₂ It is about 4.3. In addition, its cross section was observed by the average cross-sectional area of about 11μm average cross sectional area of the ultrafine fiber ² constituted of the ultrafine fiber bundle was about 325μm ^2. Further, the ultrafine fibers are bundled by the polyurethane elastomer penetrating into the inside of the ultrafine fiber bundle, and the polishing pad E1 has a basis weight of 559 g/m ² , an apparent density of 0.53 g/m ³ , and a thickness of 1.05 mm. D hardness 34. Further, the obtained polishing pad E1 was processed and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 1]

A 12-piece spunbonded sheet obtained in the same manner as in Example 1 was superposed by cross-polishing to prepare a web laminate having a total basis weight of 480 g/m ² . Then, the needle breaking oil is prevented from being sprayed on the obtained web laminate. Next, the cotton mesh layering system uses a needle cotton yarn count No. 42 and a hook number of six needles to have a depth of 10 to 15 mm from the first surface side and the second surface side thereof, respectively, and a number of bars of 900 / cm and a total of 1800 condition ² bar / cm ² for treatment needle. The area shrinkage of the cotton web laminate due to needle sticking is 30%. By such a needle-punching treatment, a wound web having a basis weight of 600 g/m ² and an interlayer peeling strength of 11.0 kg/2.5 cm can be obtained. Hereinafter, the PVA resin was dissolved and removed by hot water treatment of the wound cotton web under the same conditions as in Example 1, and the polyurethane elastomer A was further impregnated, and further heat-compressed at 150 ° C. A polishing pad precursor F0 was obtained. The polishing pad precursor F0 has a basis weight of 740 g/m ² , an apparent density of 0.63 g/m ³ , and a thickness of 1.17 mm. Further, the mass ratio of the nonwoven fabric to the polyurethane elastomer A was 87/13.

Then, by polishing the polishing pad precursor F0, the flattened polishing pad F1 can be obtained. An electron microscope was used to observe the cross section of the polishing pad F1. The average density D ₁ of the ultrafine fiber bundle was about 2550/mm ² , and the average density D ₂ of the ultrafine fiber bundle was about 2340 / mm ² , D ₁ /D ₂ It is about 1.1. Further, in the cross section thereof, an ultrafine fiber bundle having an average cross-sectional area of about 350 μm ² composed of ultrafine fibers having an average cross-sectional area of about 14 μm ^{2 was} observed. Further, the ultrafine fibers are bundled by the polyurethane elastomer penetrating into the inside of the ultrafine fiber bundle, and the polishing pad F1 has a basis weight of 613 g/m ² , an apparent density of 0.63 g/m ³ , and a thickness of 0.98 mm. D hardness 38. Further, the obtained polishing pad F1 was processed and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 2]

A 12-piece spunbonded sheet obtained in the same manner as in Example 1 was superposed by cross-polishing to prepare a web laminate having a total basis weight of 480 g/m ² . Then, the needle breaking oil is prevented from being sprayed on the obtained web laminate. Next, the cotton mesh layering system sequentially uses needle cotton yarn count No. 42, needle number one needle, and needle cotton yarn count No. 42 and hook number six needles to have a needle depth of 5 from the first surface side thereof. The needle is treated to a depth of 25 mm and a number of 1200 za/cm ² , and the needle is further needled from the second surface side at a depth of the needle depth of 0 to 5 mm and a number of sheets of 300 扎/cm ² . Tie processing. The area shrinkage of the cotton web laminate due to needle sticking is 20%. By such a needle sticking process, a wound web having a basis weight of 560 g/m ² and an interlayer peel strength of 9.4 kg/2.5 cm can be obtained.

The steam heating of the obtained wound cotton web was carried out under the conditions of an ambient temperature of 60 ° C, a relative humidity of 70%, and 500 seconds. Then, for the steam-treated wound web, the surface of the wound web was only subjected to compression treatment using a heat roller of 110 °C. In the dry state, the area shrinkage of the wound web by the steam heat treatment and the compression treatment was 35%. Then, an aqueous emulsion of a polyurethane elastomer A having a solid concentration of 15% by mass was impregnated into the wound cotton web after the treatment. Next, the coagulation treatment of the nonwoven fabric impregnated with the aqueous emulsion was carried out in a 90 ° C, 50% RH gas atmosphere, and further dried at 150 ° C to form a composite of the wound cotton web and the polyurethane elastomer A. Further, in terms of the solid content of the polyurethane elastomer A, the aqueous emulsion was impregnated with 7 mass% based on the total mass of the wound cotton web composite. Then, the PVA resin is dissolved and removed by immersing the wound cotton web composite in hot water at 95 ° C for 10 minutes, and further, by drying, a nonwoven fabric and a polyurethane composed of fiber bundles of ultrafine fibers are formed. Non-woven composite of Elastomer A.

Then, the aqueous emulsion of the polyurethane elastomer A adjusted to a solid concentration of 25% by mass was further impregnated into the nonwoven fabric composite. In terms of the solid content of the polyurethane elastomer A, the aqueous emulsion was impregnated with 15% by mass based on the total mass of the nonwoven fabric. Next, the solidification treatment of the nonwoven fabric impregnated with the aqueous emulsion was carried out in a 90 ° C, 50% RH gas atmosphere, and further dried at 150 ° C, and further heat-compressed at 150 ° C to obtain a polishing pad precursor G0. The polishing pad precursor G0 had a basis weight of 665 g/m ² , an apparent density of 0.53 g/m ³ , and a thickness of 1.25 mm. Further, the mass ratio of the nonwoven fabric to the polyurethane elastomer A was 80/20.

Then, by polishing the polishing pad precursor G0 by polishing, the flattened polishing pad G1 can be obtained. Using an electron microscope to observe the cross section of the polishing pad G1, the average density D ₁ of the ultrafine fiber bundle is about 2400 / mm ² , and the average density D ₂ of the ultrafine fiber bundle is about 400 / mm ² , D ₁ / D ₂ It is about 6.0. In addition, its cross section was observed by the average cross-sectional area of about 11μm average cross sectional area of the ultrafine fiber ² constituted of the ultrafine fiber bundle was about 325μm ^2. Further, the ultrafine fibers are bundled by the polyurethane elastomer penetrating into the inside of the ultrafine fiber bundle, and the polishing pad G1 has a basis weight of 559 g/m ² , an apparent density of 0.53 g/m ³ , and a thickness of 1.05 mm. D hardness 34. Further, the obtained polishing pad E1 was processed and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 3]

In the same manner as in Example 1, long fibers were obtained by winding up the sea-island type composite fiber yarn bundle discharged from the nozzle at 3000 m/min. Then, by winding and cutting the obtained long fibers, short fibers having a cut length of 30 mm were obtained. Then, the obtained short fibers were needled under the same conditions as in Example 1. By such a needle-punching treatment, a short-fiber wound non-woven fabric having a basis weight of 600 g/m ² and an interlayer peeling strength of 7.5 kg/2.5 cm can be obtained. Also, the area shrinkage rate of the sheet obtained by the needle stick was 25%. Using the obtained short fiber wound non-woven fabric instead of the wound cotton web, a PVA resin was dissolved and removed under the same conditions as in Example 1, to obtain a nonwoven fabric having an apparent density of 0.35 g/m ³ . Further, when the PVA resin is dissolved and removed, the ultrafine fibers are frequently peeled off by greatly stretching the short fibers and winding the nonwoven fabric. Then, the polishing pad precursor H0 was obtained by further impregnating the obtained nonwoven fabric with the obtained polyurethane nonwoven fabric A and further heat-compressing at 150 °C. The polishing pad precursor H0 has a basis weight of 480 g/m ² , an apparent density of 0.43 g/m ³ , and a thickness of 1.15 mm. Further, the mass ratio of the nonwoven fabric to the polyurethane elastomer A was 87/13.

Then, the polishing pad precursor H1 can be obtained by polishing the polishing pad precursor H0. An electron microscope was used to observe the cross section of the polishing pad H1. The average density D ₁ of the ultrafine fiber bundle was about 350/mm ² , and the average density D ₂ of the ultrafine fiber bundle was about 350 / mm ² , D ₁ /D ₂ It is about 1.0. Further, in the cross section thereof, an ultrafine fiber bundle having an average cross-sectional area of about 350 μm ² composed of ultrafine fibers having an average cross-sectional area of about 16 μm ^{2 was} observed. Further, the ultrafine fibers are bundled by the polyurethane elastomer penetrating into the inside of the ultrafine fiber bundle, and the polishing pad H1 has a basis weight of 397 g/m ² , an apparent density of 0.42 g/m ³ , and a thickness of 0.95 mm. D hardness 27. Further, the obtained polishing pad H1 was processed and evaluated in the same manner as in Example 1. The results are shown in Table 1. Further, by sufficiently stretching the short fibers and winding the nonwoven fabric, the polishing evaluation is omitted because the state in which the ultrafine fibers are frequently peeled off is caused.

[Comparative Example 4]

In the same manner as in Example 1, long fibers were obtained by winding up the sea-island type composite fiber yarn bundle discharged from the nozzle at 3000 m/min. Then, by winding and cutting the obtained long fibers, short fibers having a cut length of 30 mm were obtained. Then, the obtained short fibers were needled under the same conditions as in Example 1. By such a needle-punching treatment, a short-fiber wound non-woven fabric having a basis weight of 600 g/m ² and an interlayer peeling strength of 7 kg/2.5 cm can be obtained. Also, the area shrinkage ratio of the layer obtained by the needle stick was 25%.

The steam heat treatment and the spray treatment of the obtained short fiber wound nonwoven fabric were carried out under the same conditions as in Example 2. Then, the PVA resin was dissolved and removed by subjecting the polyurethane elastomer A to the treated short fiber-wound nonwoven fabric under the same conditions as in Example 2, further by performing the polyurethane. The impregnation imparting, drying and thermal compression at 150 ° C of the elastomer A can obtain the polishing pad precursor I0. The polishing pad precursor I0 had a basis weight of 730 g/m ² , an apparent density of 0.58 g/m ³ , and a thickness of 1.25 mm. Further, the mass ratio of the nonwoven fabric to the polyurethane elastomer A was 80/20.

Then, the polishing pad precursor I1 can be obtained by polishing the polishing pad precursor I0. An electron microscope was used to observe the cross section of the polishing pad I1. The average density D ₁ of the ultrafine fiber bundle was about 1010 / mm ² , and the average density D ₂ of the ultrafine fiber bundle was about 930 / mm ² , D ₁ / D ₂ It is about 1.1. Further, in the cross section thereof, an ultrafine fiber bundle having an average cross-sectional area of about 350 μm ² composed of ultrafine fibers having an average cross-sectional area of about 16 μm ^{2 was} observed. Further, the ultrafine fibers are bundled by the polyurethane elastomer penetrating into the inside of the ultrafine fiber bundle, and the polishing pad I1 has a basis weight of 613 g/m ² , an apparent density of 0.58 g/m ³ , and a thickness of 1.06 mm. D hardness 35. Further, the obtained polishing pad I1 was processed and evaluated in the same manner as in Example 1. The results are shown in Table 1.

[Comparative Example 5]

The pitch of the isophthalic acid-modified PET was formed by ejecting the isophthalic acid-modified PET from a nozzle for melt-composite spinning (nozzle temperature: 260 ° C). Then, the yarn bundle ejected from the nozzle is stretched by an air jet suction device disposed directly below the nozzle, and is stretched and refined, and cooled while spinning, and the average fineness of the yarn is 0.2 dtex. Long fiber. Then, by continuously collecting PET long fibers on a mobile net disposed directly below the air jet suction device, a spunbonded sheet (long fiber web) of PET having a basis weight of 30 g/m ² was obtained.

Next, the spun yarn sheets obtained by superposing 12 sheets by cross-polishing were used to prepare a web laminate having a total basis weight of 360 g/m ² . Then, the same manner as in Example 1 was carried out, and the nonwoven fabric obtained by the needle sticking treatment was obtained to obtain a non-woven fabric. Then, the obtained non-woven fabric was immersed in hot water of 70 ° C for 90 seconds to relax the stress, so that the area was shrunk by 7%. The non-woven fabric thus treated with hot water had an apparent density of 0.25 g/cm ³ .

Then, the polishing pad precursor J0 was obtained by subjecting the polyurethane elastomer A to the non-woven fabric subjected to hot water treatment under the same conditions as in Example 1 and further heat-compressing at 150 °C. The polishing pad precursor J0 has a basis weight of 390 g/m ² , an apparent density of 0.25 g/cm ³ , and a thickness of 1.55 mm. Further, the mass ratio of the nonwoven fabric to the polyurethane elastomer A was 88/12.

Then, by polishing the polishing pad precursor J0, the flattened polishing pad J1 can be obtained. An electron microscope was used to observe the cross section of the polishing pad J1, and an ultrafine fiber having an average cross-sectional area of about 20 μm ^{2 in} which the fiber bundle was not formed was observed. Further, the average density D ₁ of the cross section of the ultrafine fibers is about 300 / mm ² , and the average density D ₂ of the cross section of the ultrafine fibers is about 300 / mm ² and D ₁ / D ₂ is about 1.0. Further, the polishing pad J1 had a basis weight of 315 g/m ² , an apparent density of 0.25 g/cm ³ , a thickness of 1.25 mm, and a D hardness of 28. Further, the obtained polishing pad J1 was processed in the same manner as in Example 1. Further, as a result of the wear weight reduction measurement, the grinding evaluation was omitted because the weight was greatly reduced.

From the results of Table 1, all of the polishing pads of Examples 1 to 4 of the present invention have excellent polishing rate, polishing uniformity, abrasion resistance, flattening property, and scratch resistance. On the other hand, in the case of the polishing pad of Comparative Example 1 in which D ₁ /D ₂ is 1.1, since the polishing rate is high, the polishing rate is excellent, but the followability is low, the polishing uniformity is poor, and the abrasion resistance is low. On the other hand, in the case of the polishing pad of Comparative Example 2 in which D ₁ /D ₂ was 6, the polishing rate was low, the polishing rate was low, and the flatness was deteriorated because the followability was too high. Further, in the case of the polishing pads of Comparative Example 3 and Comparative Example 4 obtained by using the short fibers of the sea-island type composite fiber, the density of the fibers could not be formed. Therefore, only the polishing pad having low rigidity is obtained, and the abrasion resistance is low. Further, in the case of the polishing paste of Comparative Example 5 obtained by using the nonwoven fabric of the ultrafine fibers directly formed by the spunbonding method, the density of the fibers could not be formed. Therefore, only the polishing pad having low rigidity is obtained, and the abrasion resistance is low.

Industrial use possibility

The polishing pad of the present invention can be used as various products for polishing various elements such as planarization or mirroring, various substrates, and the like, for example, a semiconductor substrate, a semiconductor element, a compound semiconductor element, a compound semiconductor substrate, a compound semiconductor product, and an LED. Substrate, LED product, germanium wafer, hard disk substrate, glass substrate, glass product, metal substrate, metal product, plastic substrate, plastic product, ceramic substrate, ceramic product, and the like.

1. . . Non-woven

1a. . . Very fine fiber

1b. . . Fiber bundle of very fine fibers

2. . . Polymer elastomer

3. . . Grinding surface (first surface)

4. . . Fixed surface (second surface)

10. . . Abrasive pad

R ₁ . . . a thickness region from the surface of the polishing surface 3 to within 20% of the thickness direction

R ₂ . . . a thickness region from the surface of the fixing surface 4 to within 20% of the thickness direction

R ₃ . . . a thickness region from the surface of the abrasive surface 3 to 40 to 60% in the thickness direction

11. . . Rotating fixed disk

12. . . Paste supply nozzle

13. . . Carrier

14. . . Pad conditioner

15. . . Ground substrate

16. . . Grind paste

20. . . CMP device

Fig. 1 is a schematic longitudinal cross-sectional view of a polishing pad 10 of the present embodiment.

Fig. 2 is a partially enlarged schematic view showing the polishing pad 10 of the present embodiment.

Fig. 3 is a schematic view of a CMP apparatus 20 for chemical mechanical polishing according to the present embodiment.

1. . . Non-woven

1a. . . Very fine fiber

1b. . . Fiber bundle of very fine fibers

2. . . Polymer elastomer

3. . . Grinding surface (first surface)

4. . . Fixed surface (second surface)

R ₁ . . . a thickness region from the surface of the polishing surface 3 to within 20% of the thickness direction

R ₂ . . . a thickness region from the surface of the fixing surface 4 to within 20% of the thickness direction

R ₃ . . . a thickness region from the surface of the abrasive surface 3 to 40 to 60% in the thickness direction

10. . . Abrasive pad

Claims (13)

A polishing pad comprising a nonwoven fabric formed of a fiber bundle of an ultrafine fiber having an average cross-sectional area of 0.1 to 30 μm ² and a polymeric elastomer imparted inside the nonwoven fabric; wherein the first surface is a polished surface Further, in the case where the second surface is a fixed surface, the average number density D ₁ of the cross section of the fiber bundle in the thickness region from the first surface to the thickness direction of 20% in the longitudinal direction in the thickness direction is 1000 to 5000 / mm ² ; _{ratio of} D ₁ to the average number density D ₂ of the cross section of the fiber bundle in a thickness region from the second surface opposite to the first surface to 20% in the thickness direction (D ₁ /D ₂ ) is from 1.3 to 5. The polishing pad of claim 1, wherein the D ₁ , the D ₂ , and the average number density D of the fiber bundle cross-section in a thickness region from the first surface to the thickness direction of 40 to 60% ₃ is a relationship of D ₁ >D ₃ >D ₂ . The patentable scope of application of the polishing pad, Paragraph 2, wherein the ratio of the _{D-D. 1} and ₃ of (D ₁ / D ₃₎ is 1 to 1.4. The polishing pad of claim 2, wherein the ratio of D ₂ to the D ₃ (D ₃ /D ₂ ) is 14 to 3. The polishing pad of claim 3, wherein the ratio of D ₂ to the D ₃ (D ₃ /D ₂ ) is 1.4 to 3. The polishing pad of any one of claims 1 to 5, wherein the D ₂ is 200 to 3500 / mm ² . The polishing pad according to any one of claims 1 to 5, wherein the fiber bundle has an average cross-sectional area of 40 to 400 μm ² . The polishing pad of any one of claims 1 to 5, wherein the ultrafine fibers are filaments. The polishing pad according to any one of claims 1 to 5, wherein the polymer elastic system has a glass transition temperature of -10 ° C or less, and a storage elastic modulus of 90 to 900 MPa at 23 ° C and 50 ° C, The water absorption when saturated with water at 50 ° C is 0.2 to 5% by mass. The polishing pad according to any one of claims 1 to 5, wherein a mass ratio of the nonwoven fabric to the polymeric elastomer (non-woven fabric/polymer elastomer) is 95/5 to 55/45. The polishing pad of any one of claims 1 to 5, wherein the first surface has a D hardness of 25 to 50. The polishing pad of any one of claims 1 to 5, wherein the adhesive tape for adhering to the abrasive fixing disk is adhered to the second surface. A chemical mechanical polishing method for a chemical mechanical polishing method of a substrate; the first surface of the polishing pad according to any one of claims 1 to 12, while the polishing paste is dropped on the surface of the substrate Grinding by contact with the surface of the substrate.