WO2011052173A1

WO2011052173A1 - Polishing pad and chemical mechanical polishing method

Info

Publication number: WO2011052173A1
Application number: PCT/JP2010/006269
Authority: WO
Inventors: 高岡　信夫; 加藤　充; 知大岡本; 中山　公男
Original assignee: 株式会社クラレ
Priority date: 2009-10-30
Filing date: 2010-10-22
Publication date: 2011-05-05
Also published as: JP5629266B2; TW201120269A; JPWO2011052173A1; TWI513871B

Abstract

One aspect of the present disclosures is a polishing pad that contains a non-woven fabric formed from a fiber bundle of microfibers having an average cross-sectional area of 0.1-30 μm², and an elastomer applied within the non-woven fabric. In a vertical section in the direction of thickness, the average number density (D₁) of fiber bundle cross-sections in the region within a thickness of 20% in the direction of thickness from a first surface is 1000-5000/mm², and the ratio (D₁/D₂) between D₁ and the average number density (D₂) of fiber bundle cross sections in the region within a thickness of 20% in the direction of thickness from a second surface which is on the reverse of the first surface is 1.3-5.

Description

Polishing pad and chemical mechanical polishing method

The present invention relates to a polishing pad used for flattening or mirroring a substrate to be polished, and a chemical mechanical polishing method using the same. More specifically, for example, the present invention relates to a nonwoven fabric type polishing pad that is preferably used for surface polishing of the surface of a semiconductor wafer, polishing of a wiring board, and the like.

In recent years, along with the high integration and multilayer wiring of integrated circuits, high flatness is required for semiconductor wafers on which integrated circuits are formed.

As a polishing method for polishing a semiconductor wafer, chemical mechanical polishing (CMP) is widely used. CMP is a method of polishing by contacting a polishing pad rotating in a planetary gear shape while dripping polishing slurry onto the surface of a rotating substrate to be polished.

As a polishing pad used for CMP, a polishing pad made of a polymer foamed molding having a closed cell structure as disclosed in Patent Documents 1 to 4 below, and disclosed in Patent Documents 5 to 18 below. Such a non-woven fabric type polishing pad is known.

A polishing pad made of a foam-molded product is produced, for example, by casting and molding a two-component curable polyurethane. Such a polishing pad has higher rigidity than a nonwoven fabric type polishing pad. Therefore, a load is easily applied selectively to the convex portions of the substrate to be polished during polishing, and the polishing rate (polishing rate) is relatively high. However, a polishing pad made of a foamed molded product has the following drawbacks. When the agglomerated abrasive grains are present on the polished surface, a load is selectively applied to the agglomerated abrasive grains, so that the polished surface is easily scratched. Therefore, as described in Non-Patent Document 1, scratches and interfacial delamination are particularly noticeable when polishing a substrate having a copper wiring that is easily scratched or a low dielectric constant material having low interface adhesion. There was a drawback that it was likely to occur. Further, in cast foam molding, since it is difficult to obtain a foamed product that is uniformly foamed, there has been a drawback in that polishing non-uniformity within the polished surface tends to be high.

On the other hand, the nonwoven fabric type polishing pad includes, for example, a nonwoven fabric and a polymer elastic body such as polyurethane resin applied to the inside of the nonwoven fabric. Such a non-woven fabric type polishing pad is more flexible than a polishing pad made of a foamed molded product. Therefore, even when agglomerated abrasive grains are present on the polished surface, it is difficult for a load to be selectively applied to the agglomerated abrasive grains and scratches are less likely to be scratched on the polished surface. However, the nonwoven fabric type polishing pad has a problem that a sufficiently high leveling performance cannot be obtained. This is because the non-woven type polishing pad is flexible, so that during polishing, it deforms following the surface shape of the substrate to be polished, the polishing characteristics change over time, or the part where fibers are present is localized. It seems that this is because of stress concentration. Further, the nonwoven fabric type polishing pad has a problem that the polishing rate is low.

The following Patent Documents 15 to 18 disclose a non-woven type polishing pad using a non-woven fabric formed from a bundle of ultrafine fibers for the purpose of realizing a polishing process with higher accuracy than before. Specifically, for example, Patent Document 15 mainly includes a nonwoven fabric in which fiber bundles of polyester microfibers having an average fineness of 0.0001 to 0.01 dtex are entangled and polyurethane existing in the interior space of the nonwoven fabric. Disclosed is a polishing pad comprising a sheet-like material composed of a polymer elastic body as a component.

JP 2000-178374 A Japanese Patent Laid-Open No. 2000-248034 JP 2001-89548 A Japanese Patent Laid-Open No. 11-322878 JP 2002-9026 A Japanese Patent Laid-Open No. 11-99479 Japanese Patent Laid-Open No. 2005-212055 JP-A-3-234475 JP-A-10-128674 JP 2004-311731 A JP-A-10-225864 JP 2005-518286 JP 2003-201676 A JP 2005-334997 A JP 2007-54910 A JP 2003-170347 A JP 2004-130395 A JP 2002-172555 A

As described above, CMP using a polishing pad made of a foam-molded article has an excellent polishing rate, but has a problem that scratching tends to occur and polishing non-uniformity within the polishing surface tends to increase. Further, CMP using a non-woven type polishing pad is difficult to scratch, but has a problem that the polishing rate is low and the life is short due to low wear resistance.
In order to solve such problems, the present invention is a non-woven fabric type with excellent abrasion resistance that can achieve CMP with high polishing rate, low polishing non-uniformity in the polishing surface, and scratch-resistant CMP. An object is to provide a polishing pad.

One aspect of the present invention is a polishing pad comprising a nonwoven fabric formed from a fiber bundle of ultrafine fibers having an average cross-sectional area of 0.1 to 30 μm ² , and a polymer elastic body provided inside the nonwoven fabric, In the longitudinal section in the thickness direction, the average number density D ₁ of the cross section of the fiber bundle in the thickness region within 20% from the first surface in the thickness direction is 1000 to 5000 / mm ² , and D ₁ The ratio (D ₁ / D ₂ ) to the average number density D ₂ of the cross section of the fiber bundle in a thickness region within 20% in the thickness direction from the second surface facing the first surface is 1.3 to 5 is a polishing pad.
Another aspect of the present invention is a method for chemical mechanical polishing of a substrate, wherein the first surface of the polishing pad is brought into contact with the surface of the substrate while dripping the polishing slurry onto the surface of the substrate. This is a chemical mechanical polishing method for polishing.
The objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description and the accompanying drawings.

By polishing the substrate surface using the polishing pad of the present invention, it is possible to realize high-precision polishing at a high polishing rate. Further, scratches hardly remain on the surface of the polished substrate. Furthermore, the abrasion resistance of the polishing surface of the polishing pad is high.

1 is a schematic longitudinal sectional view of a polishing pad 10 of the present embodiment. 1 is a partially enlarged schematic view of a polishing pad 10 of the present embodiment. It is the schematic of the CMC apparatus 20 used for the chemical mechanical polishing of this embodiment.

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

As shown in FIG. 1, the polishing pad 10 is a composite sheet including a nonwoven fabric 1 formed from a fiber bundle 1 b of ultrafine fibers 1 a and a polymer elastic body 2 provided inside the nonwoven fabric 1. The thickness of the polishing pad is appropriately selected according to the application, but is preferably about 0.5 to 3 mm, more preferably about 0.7 to 2 mm. Then, in the longitudinal section in the thickness direction of the polishing pad 10, the average number density D ₁ of the cross section of the fiber bundle in the thickness region within 20% from the surface of the polishing surface 3 in the thickness direction is 1000 to 5000 / mm. ² . Moreover, the average number density D _1, and the average number density D ₂ of the cross section of the fiber bundle in the thickness region of 20% or less in the thickness direction from the surface of the fixing surface 4 facing the polishing surface 3, the ratio of (D ₁ / D ₂ ) is 1.3-5. Thus, the density of the fiber bundle 1b existing near the surface of the polishing surface 3 of the polishing pad 10 is higher than the density of the fiber bundle 1b existing near the surface of the fixed surface 4. By increasing the density of the fiber bundle 1b existing near the surface of the polishing surface 3, the rigidity and hardness on the polishing surface 3 side can be made higher than that on the fixed surface 4 side. And the rigidity by the side of the grinding | polishing surface 3 becomes high, the pressure for pushing an abrasive grain with respect to the surface of a to-be-polished base material becomes high, a polishing rate becomes high, and abrasion resistance also improves. In addition, by reducing the density of the fiber bundles 1b existing in the vicinity of the surface of the fixed surface 4, the followability and the fit to the surface of the substrate to be polished are appropriately maintained, so that scratches are generated on the surface. It becomes difficult to do.

The average number density D ₁ in longitudinal section in the thickness direction of the polishing pad 10 is calculated as follows. The polishing pad 10 is cut parallel to the thickness direction using a cutter blade, and the cut surface is observed with a scanning electron microscope (SEM) at a magnification of 100 to 1000 times and photographed. At this time, the cut surface may be dyed with a dye such as osmium oxide. Moreover, an average cross section is selected as the vertical cross section. Then, from the photographed image, it counted the number of the cross section of the fiber bundle 1b per predetermined area observed on the polished surface thickness regions R ₁ of 20% or less in the thickness direction from the surface of 3, per unit area fibers The number density (pieces / mm ² ), which is the number of cross sections of the bundle 1b, is calculated. When the polished surface is napped, the number density is calculated in a thickness region within 20% in the thickness direction from the root of the napped ultrafine fiber or fiber bundle. Further, when grooves or holes are formed on the surface of the polishing pad, the number density is calculated at a portion where the grooves and holes are not formed. Several places such number density (e.g., 5 points) evenly calculated, the number average of the obtained number density and the average number density D _1. Similarly, the average number density D ₂ counts the number of the cross section of the fiber bundle per predetermined area observed in the fixed plane thickness regions R ₂ of 20% or less in the thickness direction from the surface of the 4, per unit area The number density (pieces / mm ² ), which is the number of cross sections, is calculated. Several places such number density (e.g., 5 points) evenly calculated, the number average of the obtained number density and the average number density D _2.

The average number density D ₁ of the polishing pad 10 is 1000 to 5000 pieces / mm ² , preferably 1000 to 4500 pieces / mm ² , more preferably 1100 to 4000 pieces / mm ² , and particularly preferably 1200 to 3000 pieces / mm ² . it is in the range of mm ^2. When D ₁ is less than 1000 / mm ² , the rigidity in the vicinity of the surface of the polishing surface 3 becomes low, and the polishing rate is lowered due to the abrasive grains being hard to be pushed into the substrate to be polished. The wear resistance may be reduced. Also, if D ₁ is more than 5000 / mm ^2, by the rigidity of the vicinity of the surface of the polishing surface 3 is too high, is easily scratched.

The average number density D ₂ of the polishing pad 10 is preferably in the range of 200 to 3500 pieces / mm ² , more preferably 300 to 3000 pieces / mm ² , particularly 500 to 2500 pieces / mm ² . If D ₂ is too low, by the rigidity of the whole thing, and the polishing pad trackability and fit against the polished substrate is too high is lowered, it tends to flatten performance is reduced. Here, the planarization performance means the ability to form a polished surface having high flatness on the substrate to be polished. When the average number density D ₂ is too high, by lower trackability and fit against the polished substrate, it tends to polishing non-uniformity is high in the polishing plane. Further, since the retention of the polishing slurry inside the polishing pad is lowered, the polishing rate tends to be lowered.

The polishing pad 10 has a ratio (D ₁ / D ₂ ) between its average number density D ₁ and its average number density D ₂ of 1.3 to 5, preferably 1.4 to 3.7, more preferably The range is from 1.5 to 2.6. When D ₁ / D ₂ is less than 1.3, the polishing rate is improved by increasing the rigidity, but the non-uniformity of polishing is increased because the followability to the substrate to be polished becomes too low. At the same time, the wear resistance decreases. On the other hand, when D ₁ / D ₂ exceeds 5, the following rate with respect to the substrate to be polished becomes too high, the polishing rate is lowered, and the polishing surface 3 side and the fixed surface 4 side of the polishing pad are reduced. Since the difference in density is too large and the followability between the polished surface 3 side and the fixed surface 4 side is different, the planarization performance is lowered.

Further, the polishing pad 10, and the average number density D _1, and the average number density D _2, the mean number density D of the cross section of the fiber bundle in the region R ₃ 40 ~ 60% in the thickness direction from the surface of the polishing surface 3 ₃ is preferably in a relationship of D ₁ > D ₃ > D ₂ . In such a relationship, since the retention of the polishing slurry inside the polishing pad 1 is excellent, a higher polishing rate is realized. Further, the balance between the rigidity of the polishing pad and the followability to the substrate to be polished is excellent. As a result, the planarization performance and polishing rate are higher, and the wear resistance tends to be higher.

When D ₁ / D ₃ is in the range of 1 to 1.4, the rigidity balance inside the nonwoven fabric becomes more appropriate, the indentation hardness of the abrasive grains against the substrate to be polished increases, and the high polishing rate Tends to be obtained. Further, when D ₃ / D ₂ is in the range of 1.4 to 3, it is preferable from the viewpoint that followability to the substrate to be polished is more appropriate.

The average cross-sectional area of the ultrafine fibers forming the fiber bundle is 0.1 to 30 μm ² , and 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 0.1 μm ² , the fibers are broken and dropped during polishing, and the abrasive grains are aggregated on the dropped fibers, and scratches are easily generated. Further, in the case of a fiber bundle composed of ultrafine fibers exceeding an average cross-sectional area of 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.

The average cross-sectional area of the fiber bundle is preferably 40 to 400 μm ² , 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 and abrasion resistance of the polishing pad are improved, and fiber breakage due to needle punching during the production of the nonwoven fabric is less likely to occur. Further, when the average cross-sectional area of the fiber bundle is 400 μm ² or less, the density of the fiber bundle in the vicinity of the polishing surface can be sufficiently increased, so that the polishing rate can be further improved. The number of ultrafine fibers forming one fiber bundle is preferably 5 to 4000, and more preferably 5 to 30.

The polymer that forms the ultrafine fiber is not particularly limited. Specific examples include, for example, polyethylene terephthalate (PET), isophthalic acid-modified PET, sulfoisophthalic acid-modified PET, polybutylene terephthalate, polyhexamethylene terephthalate and other aromatic polyesters and copolymers thereof; polylactic acid, polyethylene succinate Aliphatic polyesters such as polybutylene succinate, polybutylene succinate adipate, polyhydroxybutyrate-polyhydroxyvalylate copolymer and copolymers thereof; nylon 6, nylon 66, nylon 10, nylon 11, nylon 12, Polyamides such as nylon 6-12 and copolymers thereof; Polyolefins such as polypropylene, polyethylene, polybutene, polymethylpentene, and chlorinated polyolefin; and copolymers thereof; Modified polyvinyl alcohol containing down units 25 to 70 mol%; and polyurethane, nylon type, include elastomers such as polyester. These may be used alone or in combination of two or more.

The polymer forming the ultrafine fiber has a glass transition temperature (Tg) of 50 to 300 ° C., more preferably 60 to 150 ° C., and a water absorption rate of 0.2 to 2 when saturated water absorption is performed at 50 ° C. A mass% polymer is particularly preferred.

When the glass transition temperature is within the above range, higher rigidity can be maintained, so that the planarization performance of the polishing pad is further enhanced, and the rigidity is less likely to decrease over time during polishing. Further, when the water absorption rate when saturated water absorption is performed at 50 ° C. is in the above range, the polishing pad absorbs the polishing slurry in an appropriate range, so that the polishing rate and the polishing uniformity are further improved. In addition, since the polishing slurry is not absorbed too much, a decrease in the rigidity of the polishing pad with time and a change in the flattening performance with time are suppressed.

Specific examples of such a polymer include, for example, PET (Tg 77 ° C, water absorption 1% by mass), isophthalic acid modified PET (Tg ～ 67-77 ° C, water absorption 1% by mass), sulfoisophthalic acid modified PET (Tg 67-77 ° C., water absorption 1-3% by mass), polybutylene naphthalate (Tg 85 ° C., water absorption 1% by mass), polyethylene naphthalate (Tg 124 ° C., water absorption 1% by mass), etc. Group polyester fibers; semi-aromatic polyamide fibers formed from terephthalic acid, nonanediol, and methyloctanediol copolymer polyamide (Tg 125 to 140 ° C., water absorption 1 to 3 mass%). In particular, semi-aromatic polyester polymers such as PET and modified PET containing an aromatic component as one component of a monomer unit are particularly preferable. When a semi-aromatic polyester polymer is used, it is particularly preferable from the viewpoint that it is easy to increase the rigidity of the polishing sheet, hardly changes with time due to moisture during polishing, and easily forms a dense and high-density nonwoven fabric. .

In addition, the nonwoven fabric in the present embodiment is formed from a fiber bundle of ultrafine fibers derived from a long fiber web composed of long fibers of so-called ultrafine fiber generation fibers (so-called filaments). It is preferable from the viewpoint that it is excellent, and further, the fiber omission is reduced. Such a non-woven fabric is produced, for example, by producing a long fiber web made of ultrafine fiber-generating fibers such as sea-island type composite fibers by a so-called spunbond method directly connected to melt spinning, and entanglement treatment of the long fiber web. It is manufactured by converting the ultrafine fiber generation type fiber into ultrafine fibers after forming the combined web. The filament is a fiber having a long fiber length that is not a staple intentionally cut like a short fiber having a fiber length of about 10 to 50 mm. Specifically, for example, the fiber length of the ultrafine fiber generating fiber is preferably 100 mm or more, and can be manufactured in a technical manner, and the fiber length is several m, several hundreds m, or several km unless physically cut. It may be.

Further, the nonwoven fabric in the present embodiment may be an entangled nonwoven fabric in which a knitted fabric is entangled and integrated for the purpose of improving shape stability. In addition, when using an entangled nonwoven fabric, the average number density of a fiber bundle is calculated on the basis of the thickness of only the nonwoven fabric except a knitted fabric.

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

The content ratio of the nonwoven fabric 1 and the polymer elastic body 2 (nonwoven fabric / polymer elastic body; mass ratio) is 55/45 to 95/5, more preferably 60/40 to 90/10, particularly 70/30 to The range is preferably 90/10. In such a range, a polishing pad with moderate rigidity can be obtained. When the content ratio of the polymer elastic body is too small, the rigidity of the polishing pad tends to be low. Further, when the content ratio of the polymer elastic body is too high, the rigidity of the polishing pad tends to be too high.

Further, as shown in FIG. 2, in the polishing pad 10, it is preferable that the ultrafine fibers 1a forming the fiber bundle 1b are bound by the polymer elastic body 2 and converged. Here, the ultrafine fibers 1a are converged to mean that most of the ultrafine fibers 1a existing in the fiber bundle 1b are bound and restrained by the polymer elastic body 2 that has entered the fiber bundle 1b. Means the state. Thus, by focusing the ultrafine fibers 1a, the rigidity of the polishing pad 10 is increased and the removal of the ultrafine fibers 1a is suppressed. When the ultrafine fibers 1a are not converged, the polishing pads tend to be flexible because the ultrafine fibers move.

Further, as shown in FIG. 2, it is preferable that the plurality of fiber bundles 1b are bound together by a polymer elastic body 2 existing outside the fiber bundle 1b and exist in a lump (bulk) shape. Thus, the fiber bundles are bound to each other, so that the shape stability of the polishing pad is improved and the polishing stability is improved. In addition, the converging state of the ultrafine fibers and the binding state of the fiber bundles can be confirmed by an electron micrograph of a cross section of the polishing pad.

It is preferable that the polymer elastic body that has penetrated into the inside of the ultrafine fibers and the polymer elastic body that binds the ultrafine fiber bundles are non-porous. In addition, the non-porous state means a state substantially free of many closed cells as possessed by a porous or sponge-like (hereinafter also simply referred to as porous) polymer elastic body. means. Specifically, it means that it is not a polymer elastic body having a large number of fine closed cells, such as obtained by coagulating solvent-based polyurethane. When the polymer elastic body that is focused or bound is non-porous, the polishing stability becomes high, and the slurry waste and pad waste during polishing are less likely to accumulate in the voids. And a high polishing rate can be maintained for a long time. Furthermore, since the adhesive strength with respect to the ultrafine fibers is increased, it is possible to further suppress the occurrence of scratches due to the fiber coming off. Furthermore, since higher rigidity is obtained, a polishing pad that is superior in planarization performance can be obtained.

The D hardness on the polishing surface 3 of the polishing pad 10 is preferably 25 to 50, more preferably 30 to 49, and particularly preferably 31 to 47. When the D hardness is in such a range, it is possible to obtain a polishing pad that is hardly affected by the surface shape of the substrate to be polished and has optimum rigidity in terms of planarization performance.

Next, the polymer elastic body provided inside the nonwoven fabric will be described in detail.
There is no particular limitation on the type of the polymer elastic body applied to the inside of the nonwoven fabric. Specific examples of the polymer elastic body include, for example, polyurethane resins, polyamide resins, (meth) acrylic ester resins, (meth) acrylic ester-styrene resins, (meth) acrylic ester-acrylonitrile resins. , (Meth) acrylic ester-olefin resin, (meth) acrylic ester- (hydrogenated) isoprene resin, (meth) acrylic ester-butadiene resin, styrene-butadiene resin, styrene-hydrogenated isoprene Resin, acrylonitrile-butadiene resin, acrylonitrile-butadiene-styrene resin, vinyl acetate resin, (meth) acrylic ester-vinyl acetate resin, ethylene-vinyl acetate resin, ethylene-olefin resin, silicone resin , Fluorine resin, polyester resin Ranaru elastic body, and the like. The polymer elastic bodies may be used alone or in combination of two or more. Among these, hydrogen-bonded polymer elastic bodies such as polyurethane resins, polyamide resins, polyvinyl alcohol resins and the like are particularly preferable. The hydrogen-bonding polymer elastic body is a polymer elastic body that is crystallized or aggregated by hydrogen bonding, and has high converging properties for ultrafine fibers and constrained binding properties for ultrafine fiber bundles. In addition, the polyurethane resin is particularly excellent in adhesiveness for bundling ultrafine fibers and binding fiber bundles. Also, it increases the hardness of the polishing pad and improves the stability over time in polishing. It is particularly preferable because of its superiority.

The glass transition temperature of the polymer elastic body is preferably −10 ° C. or lower, more preferably −15 ° C. or lower. If the glass transition temperature is too high, the polymer elastic body is fragile and may fall off during polishing. The glass transition temperature is calculated from the peak temperature of the loss elastic modulus in the tensile mode in the dynamic viscoelasticity measurement. The glass transition temperature depends on the α dispersion peak temperature of the polymer elastic body. For example, in the case of a polyurethane-based resin, the glass transition temperature can be reduced to −10 ° C. or lower by adjusting the composition of the polyol serving as the soft component and the ratio between the hard component and the soft component.

The polymer elastic body preferably has the following elasticity. The storage elastic modulus (G ′) of the polymer elastic body at 23 ° C. and 50 ° C. is preferably 90 to 900 MPa, and more preferably 200 to 800 MPa because the rigidity of the polishing pad is increased and the elasticity is excellent. . Further, the storage elastic modulus at ₂₃ ℃ (G 23 ') the ratio of the storage modulus at _{50 ℃ (G 50') (} G 23 '/ G 50') is 4 or less, further, not more than 3, 1 / It is preferable that it is 3 or more from the point which is excellent in polishing stability.

Further, the polymer elastic body has a water absorption rate of 0.2 to 5% by mass, more preferably 0.5 to 3% by mass when saturated water absorption is performed at 50 ° C. It is preferable from the viewpoint of excellent polishing stability.

Here, a polyurethane resin will be described in detail as a representative example of the polymer elastic body. Examples of the polyurethane resin include various polyurethane resins obtained by reacting a polymer polyol, an organic polyisocyanate, a chain extender and the like at a predetermined molar ratio.

Specific examples of the polymer polyol include, for example, polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, poly (methyltetramethylene glycol) and copolymers thereof; polybutylene adipate diol, polybutylene sebacate Diol, polyhexamethylene adipate diol, poly (3-methyl-1,5-pentylene adipate) diol, poly (3-methyl-1,5-pentylene sebacate) diol, isophthalic acid copolymer polyol, terephthalic acid copolymer Polyester polyols such as polymerized polyol, cyclohexanol copolymer polyol, polycaprolactone diol, and copolymers thereof; polyhexamethylene carbonate diol, poly (3-methyl-1,5 Pentylene carbonate) diol, polypentamethylene carbonate diol, polytetramethylene carbonate diol, poly (methyl-1,8-octamethylene carbonate) diol, polynonanemethylene carbonate diol, polycyclohexane carbonate, and other polycarbonate polyols and their co-polymers Polyester carbonate polyol etc. are mentioned. If necessary, trifunctional alcohols such as trimethylolpropane and polyfunctional alcohols such as tetrafunctional alcohols such as pentaerythritol, or ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol. Etc. You may use together short chain alcohols, such as.

Further, by incorporating a polyol component having a hydrophilic group such as a carboxyl group, a sulfonic acid group, a hydroxyl group, or a polyalkylene glycol group having 5 or less carbon atoms, particularly 3 or less carbon atoms, as a resin constituent unit, The wettability with respect to the polishing slurry can be improved.

Specific examples of the polyol component having a carboxyl group include carboxyls such as 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butanoic acid and 2,2-bis (hydroxymethyl) valeric acid. And group-containing diols. Specific examples of the polyol component having a polyalkylene glycol group having 5 or less carbon atoms include polyethylene glycol, polypropylene glycol and copolymers thereof.

As the polyol component, a polycarbonate polyol having a glass transition temperature of −10 ° C. or lower, further −20 ° C. or lower is used. The glass transition temperature of the polyurethane resin is −10 ° C. or lower, and the elastic modulus It is particularly preferable because Examples of such a polyol component include polycarbonate polyols such as alicyclic polycarbonate polyols and linear polycarbonate polyols. Among them, amorphous polycarbonate polyols having a melting point of 0 ° C. or less are particularly preferred. It is preferable to contain ˜100% by mass. A polyurethane-based resin using such a polycarbonate-based polyol as a raw material is preferable since it has high wear resistance and moderate water absorption and storage elastic modulus.

Specific examples of the amorphous polycarbonate polyol having a melting point of 0 ° C. or less include, for example, poly (3-methyl-1,5-pentylene carbonate) diol, poly (methyl-1,8-octamethylene carbonate) diol. Branched polycarbonate polyols such as poly (3-methyl-1,5-pentylene carbonate) diol and poly (methyl-1,8-octamethylene carbonate) diol; polyhexamethylene carbonate diol, polypentamethylene carbonate diol And polycarbonate-based polyols such as polytetramethylene carbonate diol, polynonane methylene carbonate diol, and polycyclohexane carbonate.

The polyol component may be used alone or in combination of two or more.

The content of the structural unit derived from the polyol component in the polyurethane-based resin is 30 to 65% by mass, more preferably 40 to 60% by mass, and particularly 45 to 55% by mass. It is preferable from the point that generation | occurrence | production of a scratch can be suppressed by this.

In addition, although the polyurethane-type resin containing the structural unit derived from the polyol component which has a hydrophilic group improves the wettability with respect to polishing slurry, there exists a tendency for a water absorption rate to become high too much. In order to obtain a polyurethane resin having a water absorption rate of 0.2 to 5% by mass when saturated water absorption is performed at 50 ° C., the copolymerization ratio of the polyol component having a hydrophilic group is 0.1 to 5%. The content is preferably 10% by mass, more preferably 0.5 to 5% by mass. By containing a polyol component having a hydrophilic group in such a content ratio as a structural unit, water absorption and wettability can be improved while minimizing swelling and softening due to water absorption. Moreover, in order to suppress that a water absorption rate becomes high too much, it is preferable to use in combination with a polyol component with low water absorption. Specific examples of such polyols include, for example, polybutylene sebacate diol, poly (3-methyl-1,5-pentylene adipate) diol, and poly (3-methyl-1,5-pentylene sebacate) diol. Polyester-based polyols and copolymers thereof; poly (3-methyl-1,5-pentylene carbonate) diol, poly (methyl-1,8-octamethylene carbonate) diol, poly (3-methyl-1,5 -Pentylene carbonate) diol, poly (methyl-1,8-octamethylene carbonate) diol, polyhexamethylene carbonate diol, polypentamethylene carbonate diol, polytetramethylene carbonate diol, polynonamethylene carbonate diol, polycyclohexane carbo Polycarbonate polyols, and the like to copolymerize the polycarbonate-based polyol, such as chromatography and.

Specific examples of the organic polyisocyanates include, for example, non-yellowing diisocyanates such as aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 4,4′-dicyclohexylmethane diisocyanate; 2,4-tri Examples thereof include aromatic diisocyanates such as range isocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, and xylylene diisocyanate polyurethane. Moreover, you may use together polyfunctional isocyanates, such as trifunctional isocyanate and tetrafunctional isocyanate, as needed. These may be used alone or in combination of two or more. Among these, cycloaliphatic diisocyanates such as 4,4′-dicyclohexylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate or aromatics Diisocyanate is preferable because it has high adhesion to ultrafine fibers, improves the focusing force of the ultrafine fibers, and provides a polishing pad with high hardness.

Specific examples of the chain extender include, for example, diamines such as hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylylenediamine, isophoronediamine, piperazine and derivatives thereof, adipic acid dihydrazide, and isophthalic acid dihydrazide; Triamines such as diethylenetriamine; tetramines such as triethylenetetramine; ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-bis (β-hydroxyethoxy) benzene, 1,4 -Diols such as cyclohexanediol; Triols such as trimethylolpropane; Pentaols such as pentaerythritol; Aminoethyl alcohol, Aminopropyl alcohol It includes amino alcohols such as and the like. These may be used alone or in combination of two or more. Among these, hydrazine, piperazine, hexamethylene diamine, isophorone diamine and derivatives thereof, and a combination of two or more of triamines such as ethylene triamine have high adhesion to fibers and moderate hardness. This is preferable because a polishing pad can be obtained. Combined with chain extenders, monoamines such as ethylamine, propylamine and butylamine; monoamine compounds containing carboxyl groups such as 4-aminobutanoic acid and 6-aminohexanoic acid; monools such as methanol, ethanol, propanol and butanol May be. Polyurethane containing a carboxyl group-containing diol such as 2,2-bis (hydroxymethyl) propionic acid, 2,2-bis (hydroxymethyl) butanoic acid, 2,2-bis (hydroxymethyl) valeric acid, etc. By introducing an ionic group such as a carboxyl group into the skeleton of the elastic body, the wettability with respect to water can be further improved.

In order to control the water absorption and storage elastic modulus, the polyurethane resin is a cross-linking agent containing two or more functional groups capable of reacting with the functional group of the monomer unit forming the polyurethane, or a polyisocyanate compound. It is also preferable to form a crosslinked structure by adding a self-crosslinking compound such as a polyfunctional blocked isocyanate compound. The combination of the functional group of the monomer unit and the functional group of the crosslinking agent includes carboxyl group and oxazoline group, carboxyl group and carbodiimide group, carboxyl group and epoxy group, carboxyl group and cyclocarbonate group, carboxyl group and aziridine group, carbonyl group Groups and hydrazine derivatives or hydrazide derivatives. Among these, a combination of a monomer unit having a carboxyl group and a crosslinking agent having an oxazoline group, a carbodiimide group or an epoxy group, a combination of a monomer unit having a hydroxyl group or an amino group and a crosslinking agent having a blocked isocyanate group, and carbonyl A combination of a monomer unit having a group and a hydrazine derivative or a hydrazide derivative is particularly preferred because crosslinking formation is easy and the resulting polishing pad has excellent rigidity and wear resistance. Examples of the crosslinking agent having a carbodiimide group include water-dispersed carbodiimide compounds such as “Carbodilite E-01”, “Carbodilite E-02”, and “Carbodilite V-02” manufactured by Nisshinbo Industries, Ltd. Examples of the crosslinking agent having an oxazoline group include water-dispersed oxazoline compounds such as “Epocross K-2010E”, “Epocross K-2020E”, and “Epocross WS-500” manufactured by Nippon Shokubai Co., Ltd. The blending amount of the crosslinking agent is preferably 1 to 20% by mass and more preferably 1.5 to 10% by mass of the active ingredient of the crosslinking agent with respect to the polyurethane resin.

The polyurethane-based resin is within the range that does not impair the effects of the present invention, and the penetrant, antifoaming agent, lubricant, water repellent, oil repellent, thickener, extender, curing accelerator, antioxidant, ultraviolet absorber Further, it may further contain an antifungal agent, a foaming agent, a water-soluble polymer compound such as polyvinyl alcohol and carboxymethyl cellulose, a dye, a pigment, inorganic fine particles and the like.

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

(1) Web production process In this production method, first, a long fiber web made of sea-island type composite fibers obtained by melt spinning a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin is produced. In this embodiment, the sea-island type composite fiber is used as the composite fiber for forming the ultra-fine fiber. However, instead of the sea-island type composite fiber, conventionally known ultra-fine fiber generation such as a multilayer laminated cross-sectional fiber is generated. Mold fibers may be used.

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 the water-soluble thermoplastic resin, and then combining them. Then, the ultrafine fiber is formed by dissolving or removing the water-soluble thermoplastic resin from the sea-island type composite fiber. The thickness of the sea-island type composite fiber is preferably 0.5 to 3 dtex, more preferably 0.8 to 2.5 dtex, from the viewpoint of industrial properties.

The water-soluble thermoplastic resin is a polymer that is dissolved or removed by heating or pressure under an aqueous solution such as water or an aqueous alkali solution or an acid aqueous solution. Specific examples of the water-soluble thermoplastic resin include, for example, modified polyester obtained by copolymerizing a compound containing polyvinyl alcohol (PVA), a PVA copolymer, polyethylene oxide polyethylene glycol and / or an alkali metal sulfonate, and the like. Is mentioned. In these, PVA and a PVA-type copolymer are preferable from the point which is excellent in the solubility with respect to water.

Further, as the water-insoluble thermoplastic resin, various polymers for forming the above-described ultrafine fibers can be used without any particular limitation. The water-insoluble thermoplastic resin may contain various additives. Specific examples of the additive include, for example, a catalyst, an anti-coloring agent, a heat-resistant agent, a flame retardant, a lubricant, an antifouling agent, a fluorescent brightening agent, a matting agent, a coloring agent, a gloss improving agent, an antistatic agent, and an antibacterial agent. , Anti-mite agents, inorganic fine particles and the like.

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

First, a water-soluble thermoplastic resin and a water-insoluble thermoplastic resin are melt-kneaded with separate extruders, and molten resin strands are simultaneously discharged from different spinnerets. Then, after the discharged strands are combined with the composite nozzle, the sea-island type composite fibers are formed by discharging from the nozzle holes of the spinning head. The number of islands in the sea-island type composite fiber is preferably 5 to 4000 islands / fiber, more preferably 10 to 1000 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 drawn by a high-speed air flow at a speed corresponding to a take-up speed of 1000 to 6000 m / min so as to obtain a desired fineness using a suction device such as an air jet nozzle. . Thereafter, the stretched composite fibers are deposited on a movable collection surface to form a long fiber web. At this time, the long fiber web deposited may be partially crimped as necessary. The basis weight of the long fiber web is preferably in the range of 20 to 500 g / m ² from the viewpoint of industrial properties.

(2) Web entanglement process Next, the web entanglement process which forms an entanglement web by overlapping and intertwining the obtained many long fiber webs is demonstrated. The entangled web is obtained by entanglement treatment with the long fiber web by a known nonwoven fabric manufacturing method such as needle punching or high-pressure water flow treatment.

First, silicone oil or mineral oil such as needle breakage prevention oil, antistatic oil, and entanglement oil is applied to the long fiber web. In order to reduce unevenness in weight per unit area, two or more fiber webs may be overlapped with a cross wrapper and an oil agent may be applied. Then, the entanglement process which entangles a fiber three-dimensionally with a needle punch is performed. By performing the needle punching, an entangled web having a high fiber density and hardly causing the fibers to come off can be obtained. In the needle punch, the density of fiber bundles on the front side and the back side can be made different by changing the needle punch conditions on the front side and the back side.

Needle conditions such as the type and amount of the oil agent, needle shape, needle depth, and number of punches in the needle punch are determined by the density of the fiber bundle on the front surface that becomes the polishing surface and the density of the fiber bundle on the back surface that becomes the fixed surface. Are appropriately selected so as to obtain an appropriate density difference.

The number of barbs on the needle is selected from, for example, 1 to 9 barbs, and is preferably as large as possible without causing needle breakage. Moreover, it is preferable to set the piercing depth of the needle within a range where the pattern after needle punching is not strong on the web surface. Specifically, for example, a punching process is initially performed with a 6 to 9 barb needle at a depth of 5 to 25 mm, and a depth of 0.1 to 15 mm with a 3 to 6 barb needle in the latter half. The condition which entangles the fiber of intensively is mentioned. The number of needle punches is appropriately selected depending on the shape of the needle, the type and amount of oil used, and specifically, about 500 to 5000 punches / cm ² is preferable, and the number of punches from the back side is preferred. Thus, the number of punches from the surface side is preferably 1.5 to 2 times or more. Moreover, it is preferable to use a needle having a larger number of barbs on the front surface side than on the back surface side, and it is preferable that the needle piercing depth is shallower. Moreover, it is preferable to increase the number of punches and selectively entangle the fibers on the surface side with a barb of the needle.

In addition, the entanglement web after the needle punch is entangled with a high fiber density so that the basis weight of the long fiber web before the needle punch is 1.2 times or more, and more preferably 1.5 times or more. This is preferable because a web is obtained. The basis weight of the entangled web is appropriately selected according to the thickness of the target polishing pad, but is preferably in the range of 100 to 1500 g / m ² from the viewpoint of excellent handleability.

In addition, the delamination force of the entangled web is 2 kg / 2.5 cm or more, and more preferably 4 kg / 2.5 cm or more. This is preferable because a high entangled web can be obtained. Note that the delamination force is a measure of the degree of three-dimensional entanglement. When the delamination force is too small, the fiber density of the fiber entangled body is not sufficiently high. Moreover, although the upper limit of the delamination force of an entangled nonwoven fabric is not specifically limited, It is preferable that it is about 30 kg / 2.5 cm or less from the point of an entanglement process efficiency.

(3) Wet heat shrinkage treatment process Next, the fiber density and the degree of entanglement of the entangled web are increased by shrinking the entangled web with heat and moisture. In this step, the entangled web containing the long fibers can be subjected to wet heat shrinkage, so that the entangled web can be greatly shrunk compared to the case where the entangled web containing the short fibers is subjected to wet heat shrinkage, Therefore, the fiber density of the ultrafine fibers becomes dense. The wet heat shrinkage treatment is preferably performed by steam heating.

As the steam heating conditions, it is preferable to perform heat treatment for 60 to 600 seconds at an ambient temperature of 60 to 130 ° C. and a relative humidity of 75% or more, and further a relative humidity of 80% or more. Such heating conditions are preferable because the entangled web can be shrunk at a high shrinkage rate. In addition, when relative humidity is too low, there exists a tendency for shrinkage | contraction to become inadequate because the water | moisture content which contacted the fiber dries rapidly.

The wet heat shrinkage treatment is preferably performed so that the area shrinkage rate of the entangled web is 35% or more, and further 40% or more. By shrinking at such a high shrinkage rate, the fiber density becomes dense. The upper limit of the area shrinkage rate is not particularly limited, but is preferably about 80% from the viewpoint of shrinkage limit and processing efficiency. The area shrinkage rate (%) is expressed by the following formula (1): (area of the sheet surface before the shrinking process−area of the sheet surface after the shrinking process) / area of the sheet surface before the shrinking process × 100. 1),
Is calculated by

The entangled web subjected to the wet heat shrinkage treatment in this way may be further increased in fiber density by being heated or pressed at a temperature equal to or higher than the heat deformation temperature of the sea-island composite fiber. At this time, the density gradient of the fiber bundle can also be formed by heating and pressing the front side and the back side under different conditions. Examples of pressing conditions with a heated roll include conditions of a roll temperature of 110 to 150 ° C. and a roll pressure of 0.05 to 0.4 Mpa. The basis weight of the entangled web after the shrinkage treatment relative to the basis weight of the entangled web before the shrinkage treatment is preferably 1.2 to 4 times, and more preferably 1.5 to 4 times.

(4) Polymer elastic body filling process I
Prior to performing the ultrafine fiber treatment of the sea-island type composite fiber of the entangled web subjected to the shrinkage treatment, the sea-island type composite fiber may be bound by applying a polymer elastic body to the inside of the entangled web. In this way, by applying a polymer elastic body to the entangled web before performing the ultrafine fiber treatment, the shape stability of the entangled web is enhanced, and the density gradient of the fiber bundle of the resulting polishing pad is adjusted. be able to.

In this step, the entangled web subjected to the shrinkage treatment is impregnated with the aqueous liquid of the polymer elastic body, and then the polymer elastic body is solidified to impregnate the polymer web with the polymer elastic body.

The aqueous liquid of the polymer elastic body is an aqueous dispersion in which the component forming the polymer elastic body is dispersed in the aqueous medium, or the aqueous solution in which the component forming the polymer elastic body is dissolved in the aqueous medium. . The solid content concentration of the aqueous liquid of the polymer elastic body is preferably 10% by mass or more, and more preferably 15% by mass or more.

Since an aqueous dispersion of a polymer elastic body has a low viscosity even at a high concentration and is excellent in impregnation permeability, it can be easily filled into an entangled web and has excellent adhesion to fibers. Therefore, the polymer elastic body impregnated by this step can strongly restrain the sea-island type composite fiber and can easily increase the apparent density of the polishing pad. In addition, since a polymer elastic body obtained by coagulating an aqueous dispersion of a polymer elastic body has high wettability to water, a polishing pad capable of holding a large amount of abrasive grains is obtained.

Aqueous dispersions include suspensions and emulsions. The average particle diameter of the elastic polymer dispersed in the aqueous dispersion is preferably about 0.01 to 0.2 μm.

The method for preparing the aqueous dispersion is not particularly limited. For example, in the case of a polyurethane-based resin, a monomer unit having a hydrophilic group such as a carboxyl group, a sulfonic acid group, a hydroxyl group, a polyalkylene glycol group having 5 or less carbon atoms, particularly 3 or less carbon atoms is contained as a resin constituent unit. Dispersibility in an aqueous medium can be imparted. The copolymerization ratio of the monomer unit having such a hydrophilic group is 0.1 to 10% by mass, and further 0.5 to 5% by mass while minimizing swelling and softening due to water absorption. From the point that water absorption and wettability can be improved.

Also, by using a surfactant, the polyurethane resin particles can be emulsified or suspended in an aqueous medium. Specific examples of the surfactant used for emulsification or suspension include, for example, sodium lauryl sulfate, ammonium lauryl sulfate, sodium polyoxyethylene tridecyl ether acetate, sodium dodecylbenzene sulfonate, sodium alkyldiphenyl ether disulfonate, dioctyl sulfosuccinic acid Anionic surfactants such as sodium; nonionic properties such as polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene-polyoxypropylene block copolymer Surfactant etc. are mentioned. Moreover, you may use what is called reactive surfactant which has reactivity. Moreover, heat-sensitive gelation property can also be provided to a polyurethane resin by selecting the cloud point of surfactant suitably.

Examples of the method for impregnating the entangled web with the aqueous liquid of the polymer elastic body include a method using a knife coater, a bar coater, or a roll coater, or a dipping method. The polymer elastic body can be solidified by drying the entangled web impregnated with the aqueous liquid of the polymer elastic body. Examples of the drying method include a method of heat treatment in a drying apparatus at 50 to 200 ° C. and a method of heat treatment in a dryer after infrared heating. When the entangled web is impregnated with an aqueous liquid of a polymer elastic body and then dried, the aqueous liquid migrates to the surface layer due to evaporation of moisture from the surface layer of the entangled web. It is preferable that the polymer elastic body is unevenly distributed on the surface layer to form a density gradient of the fiber bundle by drying under conditions that promote this migration. As specific examples of the heat treatment temperature of the hot air dryer, for example, 130 to 170 ° C., more preferably 140 to 170 ° C. is preferable. Using such a method, by increasing the density on the polished surface side not only due to the difference in density of fiber bundles but also due to the difference in density due to the polymer elastic body, the polished surface side becomes more dense and wear resistant. A polishing pad with higher properties can be obtained.

(5) Ultrafine fiber formation process The process of forming ultrafine fiber 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 sea-island composite fiber is dissolved or removed by using water, an alkaline aqueous solution, an acidic aqueous solution, or the like.

In this step, first, the entangled web or the entangled web provided with the polymer elastic body is immersed in hot water such as water, an alkaline aqueous solution, an acidic aqueous solution, etc., and subjected to hot water treatment. Moreover, in order to improve dissolution efficiency, you may perform the nip process by a roll, a high pressure water flow process, an ultrasonic process, a shower process, a stirring process, a stagnation process, etc. as needed. In addition, in order to make the fiber bundle of a fixed surface low density, you may adjust by performing a stagnation process with a high-speed water stream or a machine.

In addition, without performing the wet heat shrinkage treatment step (3), the shrinkage treatment of the entangled web and the ultra-fine fiber of the sea-island type composite fiber may be simultaneously performed in this step. As a specific example of the method for simultaneously performing the shrinkage treatment and the ultrafine fiber formation, for example, an entangled web is immersed in hot water at 65 to 90 ° C. for 5 to 300 seconds as a first step, and further, As the second stage, conditions for treatment in hot water at 85 to 100 ° C. for 100 to 600 seconds can be mentioned.

(6) Polymer elastic body filling step II
Next, a process of applying a polymer elastic body in order to bundle the ultrafine fibers and further restrain the ultrafine fiber bundles will be described. In the ultrafine fiber forming step (5), the sea-island type composite fiber is subjected to ultrafine fiber treatment, whereby the water-soluble thermoplastic resin is removed and voids are formed inside the ultrafine fiber bundle. In this step, the ultrafine fibers are focused by applying a polymer elastic body to such voids. At the same time, the ultrafine fiber bundles are further restrained by the polymer elastic body. When the ultrafine fibers form a fiber bundle, the aqueous liquid of the polymer elastic body is easily absorbed into the fiber bundle by capillary action. The aqueous liquid of the polymer elastic body used in this step may be the same as the aqueous liquid described in the polymer elastic body filling step I. Also, the method for filling and coagulating the polymer elastic body may be the same as the method described in the polymer elastic body filling step I. In this way, a polishing pad precursor is formed.

(7) Finishing process The polishing pad of this embodiment is obtained by performing a planarization process on the obtained polishing pad precursor. In the flattening treatment, for example, the polishing pad precursor is hot press-molded to a predetermined thickness, or the surface is polished with sandpaper, needle cloth, diamond, etc., so that the surface is finished smoothly and the thickness is adjusted. Process. The thickness of the polishing pad thus finished is preferably about 0.5 to 3 mm.

Also, the surface of the polishing pad may be brushed. By raising the surface, the contact area between the polishing surface of the polishing pad and the substrate to be polished is increased, and wettability with the polishing slurry is improved. For the raising treatment, a method of buffing the surface of the polishing pad with sandpaper is used. As the sandpaper, for example, it is preferable to use one having an abrasive grain number of # 40 to # 80. Specific examples of the raising process include, for example, a continuous raising process using a contact type buffing machine, an emery type buffing process, a buffing process combining a contact type and an emery type, and the like. In addition, in order to obtain a uniform raised state, the raised surface of the polishing pad may be pressed.

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

Next, a chemical mechanical polishing method using the polishing pad of this embodiment will be described in detail with reference to FIG. FIG. 3 is a side view showing a state of the 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 circular rotary surface plate 11, a slurry supply nozzle 12, a carrier 13, and a pad conditioner 14 as shown in FIG. A CMP apparatus 20 is used. A polishing pad 10 is adhered to the surface of the rotating surface plate 11 with a fixed surface 4 by a double-sided tape. The carrier 13 supports the substrate 15 to be polished.
In the CMP apparatus 20, the rotating surface plate 11 is rotated in a direction indicated by an arrow by a motor (not shown). Further, the carrier 13 is rotated in the direction indicated by an arrow by a motor (not shown) in a planetary gear shape within the surface of the rotating surface plate 11. The pad conditioner 14 is also rotated in a planetary gear shape in the plane of the rotating surface plate 11 by a motor (not shown), for example, in the direction indicated by the arrow.

First, the surface of the polishing pad 10 is conditioned by pressing the rotating pad conditioner 14 against the surface of the polishing pad 10 while flowing distilled water on the surface of the polishing pad 10 that is fixed to the rotating platen 11 and rotating. Next, a polishing slurry 16 containing various chemical components and hard fine abrasive grains is supplied from the slurry supply nozzle 12 to the surface of the rotating polishing pad 10. Then, the substrate 15 to be polished, which is fixed to the carrier 13 and rotates, is pressed against the polishing pad 10 in which the polishing slurry 16 has spread evenly. Then, the polishing process is continued until a predetermined flatness is obtained. The quality of the finished product is affected by adjusting the pressing force applied during polishing and the speed of the relative movement between the rotating surface plate 11 and the carrier 13.

In the chemical mechanical polishing method of this embodiment, the polishing pad 10 is fixed to the surface of the rotating surface plate 11 with the fixed surface 4. By fixing the polishing pad 10 with the fixed surface 4, the polishing surface 3 having a high number density and high rigidity of the fiber bundle becomes the outer surface, so that the polishing rate and the wear resistance are increased. Polishing non-uniformity is reduced. Further, since the surface layer on the fixed surface 4 side fixed to the rotating surface plate 11 has a low number density of fiber bundles and a low rigidity, it is possible to maintain appropriate followability and fit to the surface of the substrate 15 to be polished.

The components of the polishing slurry 16 are appropriately selected depending on the type of the substrate 15 to be polished. Specific examples of the abrasive grains include SiO ₂ , Al ₂ O ₃ , CeO ₂ , Mn ₂ O ₃ , diamond particles having a particle diameter of several tens to several hundreds of nanometers. Specific examples of the chemical component include components that modify the surface to be polished, such as acid and alkali, and surfactants.

Such a chemical mechanical polishing method of this embodiment can be used for polishing various substrates. Specific examples of the base material include, for example, insulating materials such as silicon, silicon oxide, silicon oxyfluoride, and organic polymers; conductive materials such as copper, aluminum, and tungsten; barrier materials such as tantalum, titanium, tantalum nitride, and titanium nitride. , Etc. Specific examples of the application include, for example, a silicon wafer, a compound semiconductor wafer, a semiconductor wafer, a semiconductor device, a liquid crystal member, an optical element, a crystal, an optical substrate, an electronic circuit substrate, an electronic circuit mask substrate, a multilayer wiring substrate, and a hard disk. And polishing of MEMS (micro-electro-mechanical systems) base materials. The polishing may be any of primary polishing, secondary polishing (adjustment polishing), finish polishing, mirror polishing, and the like.

Hereinafter, the present invention will be specifically described by way of examples. The scope of the present invention is not limited by the description of the examples.
First, the evaluation methods used in this example will be described together.

[Evaluation methods]
(1) Measurement of the average number density (D ₁ , D ₂ , D ₃ ) of the ultrafine fiber bundle, the average cross-sectional area of the single fiber, and the average cross-sectional area of the fiber bundle In the thickness direction, the polishing pad is used with a cutter blade A cut surface in the thickness direction was formed by cutting in parallel. The obtained cut surface was stained with osmium oxide. The cut surface was observed with a scanning electron microscope (SEM) at a magnification of 100 to 1000 times, and the image was taken. And the cross-sectional area of 100 ultra-fine fiber bundles selected at random from the obtained image was calculated | required, and the average value was made into the average cross-sectional area of an ultra-fine fiber bundle. In addition, the cross-sectional area of 100 ultrafine fibers forming the ultrafine fiber bundle was obtained, and the average value was defined as the average cross-sectional area of single ultrafine fibers.
Further, from the obtained image, five regions of 0.1 mm square were selected evenly in the thickness region within 20% in the thickness direction from the surface of the polishing pad, and the number of ultrafine fiber bundles at each location was counted. From the result, the number of ultrafine fiber bundles present per 1 mm ² was calculated. The average of five points was _{D 1.}
Further, from the obtained image, five regions of 0.1 mm square were selected evenly in the thickness region within 20% from the back surface of the polishing pad in the thickness direction, and the number of ultrafine fiber bundles at each location was counted. From the result, the number of ultrafine fiber bundles present per 1 mm ² was calculated. The average of five points was _{D 2.}
Further, from the obtained image, five uniform 0.1 mm square regions were selected in the vicinity of 50% in the thickness direction from the surface of the polishing pad, and the number of ultrafine fiber bundles at each location was counted. From the result, the number of ultrafine fiber bundles present per 1 mm ² was calculated. The average of five points was _{D 3.}

(2) Delamination strength of entangled web From the obtained entangled web, a test piece on a rectangle having a length of 23 cm and a width of 2.5 cm was prepared. Then, at one end of the test piece, a cut was made with a razor blade at substantially the center in the thickness direction. And about 10 cm from the end was pulled by hand and peeled off. Then, the ends of both peeled pieces were each fixed to a chuck of a tensile tester. Then, it was pulled with a tensile tester to obtain a stress-strain curve (SS curve), and the peel strength was obtained from the stress of the flat portion. The tensile speed was 100 mm / min. In addition, the obtained result is an average value of three test pieces.

(3) Measuring method of D hardness of polishing pad D hardness of the polishing surface of the polishing pad was measured according to JIS K 6253 using a hardness meter D type (manufactured by Kobunshi Keiki Co., Ltd.). The load was set to 5 kg.

(4) Abrasion loss The Taber abrasion of the polishing surface of the polishing pad cut into a circle having a diameter of 13 cm was measured by a method according to JIS K5600-5-9. The measurement was performed under the conditions of a wear wheel: H-22, a load: 500 g, and a rotation speed: 1000 times. The weight loss (mg), which is the difference between the pre-measurement weight and the post-measurement weight, was determined.

(5) Measurement of Glass Transition Temperature (T _g ) of Polymer Elastic Body A film having a length of 4 cm, a width of 0.5 cm, and a thickness of 400 μm ± 100 μm made of a polymer elastic body constituting a polishing pad was prepared. Then, after measuring the thickness of the film with a micrometer, using a dynamic viscoelasticity measuring device (DVE Rheospectr, manufactured by Rheology Co., Ltd.) under the conditions of a frequency of 11 Hz and a heating rate of 3 ° C./min. The dynamic viscoelasticity was measured, and the main dispersion peak temperature of the loss elastic modulus was defined as the glass transition temperature.

(6) Method for Measuring Storage Elastic Modulus of Polymer Elastic Body at 23 ° C. and 50 ° C. A film having a length of 4 cm, a width of 0.5 cm, and a thickness of 400 μm ± 100 μm was prepared from the polymer elastic body constituting the polishing pad. Then, after measuring the thickness of the film with a micrometer, using a dynamic viscoelasticity measuring device (DVE Rheospectr, manufactured by Rheology Co., Ltd.) under the conditions of a frequency of 11 Hz and a heating rate of 3 ° C./min. The dynamic viscoelastic modulus at 23 ° C. and 50 ° C. was measured, and the storage elastic modulus was calculated.

(7) Method for Measuring Saturated Water Absorption Rate of Polymer Elastic Body A 200 μm-thick film obtained by drying the polymer elastic body constituting the polishing pad at 50 ° C. was heat-treated at 130 ° C. for 30 minutes. And it was left to stand on the conditions of 20 degreeC and 65% RH for 3 days. And the mass at the time of drying at this time was measured. Then, the dried film was immersed in 50 ° C. water for 2 days. And immediately after taking out from 50 degreeC water, the excess water drop etc. of the outermost surface of a film were wiped off, and the mass after water absorption was measured. And the saturated water absorption was computed by the following formula.
Saturated water absorption (%) = [(mass after water absorption−mass at drying) / mass at drying] × 100

(8) Polishing performance of polishing pad A double-sided adhesive tape was affixed to the fixed surface of the polishing pad and fixed to a rotating surface plate of a CMP polishing apparatus ("PP0-60S" manufactured by Nomura Corporation). Then, using a diamond dresser with count # 200 (MEC200L manufactured by Mitsubishi Materials Corporation), polishing for 18 minutes while flowing distilled water at a rate of 120 mL / min under conditions of a pressure of 177 kPa and a dresser rotation speed of 110 rpm. Conditioning (seasoning) was performed by grinding the pad surface.
Next, the polishing slurry was supplied to the surface of the polishing pad fixed to the rotating surface plate. As the polishing slurry, a slurry obtained by diluting Cabot abrasive slurry SS25 twice with distilled water was used. The supply amount of the polishing slurry was 120 ml / min. Then, an 8 inch diameter silicon wafer having an oxide film surface was polished for 100 seconds under the conditions of a platen rotation speed of 50 rotations / minute, a head rotation speed of 49 rotations / minute, and a polishing pressure of 35 kPa.

Then, the thickness of the oxide film before and after polishing was measured at 49 points within the silicon wafer surface, and the polished thickness at each point was divided by the polishing time to obtain the polishing rate (nm / min). It was. Further, the average value of the 49 polishing rates was defined as the average polishing rate (R), and the standard deviation (σ) of the polishing rate was determined. And
The non-uniformity was calculated by the formula (1): non-uniformity (%) = (σ / R) × 100 (1). It shows that it is grind | polished uniformly within a grinding | polishing surface, so that the value of nonuniformity is small. And a highly accurate grinding | polishing process is realizable.

Further, the polishing rate stability was calculated by the formula (2): polishing rate stability (%) = (polishing rate maximum value−polishing rate minimum value) / polishing rate average value × 100 (2).
Further, the number of scratches having a size of 0.16 μm or more present on the surface of the silicon wafer having the polished oxide film is measured by using a wafer surface inspection device Surfscan SP1 (manufactured by KLA-Tencor) to scratch. Sex was evaluated.

[Example 1]
PVA resin was used as the island component, and isophthalic acid-modified PET having a modification degree of 6 mol% was used as the sea component. The isophthalic acid-modified PET had a water absorption of 1% by mass when saturated with water at 50 ° C., and its glass transition temperature was 77 ° C. A strand of sea-island type composite fibers was formed by discharging PVA resin and isophthalic acid-modified PET at a ratio of 25:75 (mass ratio) from a 25 island / fiber melt compound spinning die (die temperature 260 ° C.). . Then, the strand discharged from the die was cooled while being stretched and thinned by an air jet suction device installed immediately below the die, thereby spinning a sea-island composite filament having an average fineness of 2.0 dtex. The suction force of the air jet suction device was adjusted so that the spinning speed obtained indirectly from the ratio of the discharge amount per unit time and the fineness of the obtained long fibers was 4000 m / min. And the sea-island type | mold composite filament was continuously collected on the mobile net installed directly under the air jet suction apparatus, and the spunbond sheet (long fiber web) with a weight of 40 g / m < ² > was obtained.

Next, 12 spunbond sheets obtained were overlapped by cross-wrapping to produce a web laminate having a total basis weight of 480 g / m ² . And the needle | hook breaking prevention oil agent was sprayed to the obtained web laminated body. Next, the web laminated body was used from the first surface side with a needle depth of 5 to 4, using a needle count of 42, a needle needle with 3 barbs, and a needle needle with a needle count of 42 and 6 barbs. Needle punch processing is performed at a depth of 25 mm and a punch number of 1500 punch / cm ² , and further, needle punch processing is performed at a needle depth of 0 to 15 mm from the second surface side and a punch number of 500 punch / cm ^2. It was done. The area shrinkage rate of the web laminate by needle punching was 30%. By such a needle punching process, an entangled web having a basis weight of 600 g / m ² and a delamination strength of 11.0 kg / 2.5 cm was obtained.

Next, the obtained entangled web was immersed in hot water at 70 ° C. for 90 seconds to relieve the stress of the island component, thereby shrinking the area by 43%, and further immersed in hot water at 95 ° C. for 10 minutes. The PVA resin was dissolved and removed. In addition, the area shrinkage rate of the entangled web by the hot water treatment was 45% in the dry state. A nonwoven fabric composed of fiber bundles of ultrafine fibers was obtained by the hot water treatment. The nonwoven fabric had a basis weight of 780 g / m ² and an apparent density of 0.55 g / cm ³ .

Then, the obtained nonwoven fabric was impregnated with an aqueous emulsion of polyurethane elastic body A adjusted to a solid content concentration of 25% by mass. The average particle size of the polyurethane elastic body A in the aqueous emulsion was 0.05 μm.

The polyurethane elastic body A is a polymer as follows. The polyurethane elastic body A contains 1.5% by mass of 4,4′-dicyclohexylmethane diisocyanate, short-chain amine, short-chain diol, and 2,2-bis (hydroxymethyl) propionic acid with respect to 50% by mass of the polymer diol. This is a crosslinked polyurethane resin obtained by crosslinking 100 parts by mass of a polycarbonate-based non-yellowing polyurethane resin obtained by reacting 50% by mass of a copolymerized with 5 parts by mass of a carbodiimide-based crosslinking agent. The polymer diol comprises 99.9: 0.1 (molar ratio) of a copolymer polyol of hexamethylene carbonate and pentamethylene carbonate, which is an amorphous polycarbonate polyol, and a polyalkylene glycol having 2 to 3 carbon atoms. ).

The polyurethane elastic body A had a water absorption rate of 2% by mass, a storage elastic modulus at 23 ° C. of 450 MPa, a storage elastic modulus at 50 ° C. of 300 MPa, and a glass transition temperature of −25 ° C. Further, the aqueous emulsion was impregnated in an amount of 15% by mass with respect to the mass of the nonwoven fabric in terms of solid content of the polyurethane elastic body A. Next, the nonwoven fabric impregnated with the aqueous emulsion is coagulated at 90 ° C. in a 50% RH atmosphere, further dried at 150 ° C., and further hot-pressed at 150 ° C. to obtain the polishing pad precursor A0. Obtained. The polishing pad precursor A0 had a basis weight of 910 g / m ² , an apparent density of 0.62 g / cm ³ , and a thickness of 1.45 mm. Moreover, the mass ratio of the nonwoven fabric and the polyurethane elastic body A was 87/13.

And polishing pad A1 planarized was obtained by carrying out the buffing grinding process of polishing pad precursor A0. Was a cross section of the polishing pad A1 was observed by an electron microscope, the average the density _{D 1} is about 2500 / mm ² of the microfine fiber bundles, average the density _{D 2} of the microfine fiber bundles from about 1200 / mm ² D ₁ / D ₂ was about 2.1. Further, in its cross-section, an average microfine fiber bundles of the cross-sectional area of about 320 .mu.m ² to average cross-sectional area consists of ultrafine fibers of about 11 [mu] m ² was observed. The ultrafine fibers are focused by a polyurethane elastic body that has entered the inside of the ultrafine fiber bundle, and the ultrafine fiber bundles are also bound by the polyurethane elastic body. The polishing pad A1 had a basis weight of 750 g / m ² , an apparent density of 0.61 g / cm ³ , a thickness of 1.23 mm, and a D hardness of 37.

The obtained polishing pad A1 was cut into a circular shape having a diameter of 51 cm, and was further processed to form a grid-like groove having a width of 2.0 mm, a depth of 1.0 mm, and an interval of 15.0 mm on the main surface. . The polishing performance of the polishing pad A1 was evaluated by the evaluation method described above. The results are shown in Table 1.

[Example 2]
The entangled web obtained in Example 1 was subjected to steam heating under the conditions of an atmospheric temperature of 60 ° C., a relative humidity of 80%, and 500 seconds. And only the surface was press-processed with the 120 degreeC hot roll with respect to the entangled web by which the steam heat processing was carried out. The area shrinkage ratio of the entangled web by the steam heat treatment and the press treatment was 40% in the dry state. Then, the treated entangled web was impregnated with an aqueous emulsion of polyurethane elastic body A having a solid concentration of 15% by mass. Next, the entangled web impregnated with the aqueous emulsion is coagulated in an atmosphere of 90 ° C. and 50% RH, and further dried at 150 ° C., whereby a composite of the entangled web and the polyurethane elastic body A ( Entangled web composite). The aqueous emulsion was impregnated in an amount of 7% by mass with respect to the total mass of the entangled web composite in terms of solid content of the polyurethane elastic body A. Then, the resulting entangled web composite is immersed in hot water at 95 ° C. for 10 minutes to dissolve and remove the PVA resin, and further dried to form a nonwoven fabric comprising a fiber bundle of ultrafine fibers and a polyurethane elastic body A. A composite (nonwoven fabric composite) was formed.

And the nonwoven fabric composite was further impregnated with an aqueous emulsion of polyurethane elastic body A adjusted to a solid content concentration of 25% by mass. The aqueous emulsion was impregnated in an amount of 15% by mass with respect to the total mass of the nonwoven fabric composite in terms of solid content of the polyurethane elastic body A. Next, the nonwoven fabric composite impregnated with the aqueous emulsion is coagulated in an atmosphere of 90 ° C. and 50% RH, further dried at 150 ° C., and further hot-pressed at 150 ° C., whereby a polishing pad precursor is obtained. B0 was obtained. The polishing pad precursor B0 had a basis weight of 730 g / m ² , an apparent density of 0.58 g / cm ³ , and a thickness of 1.26 mm. Moreover, the mass ratio of the nonwoven fabric and the polyurethane elastic body A was 80/20.

And polishing pad B1 planarized was obtained by carrying out the buffing grinding process of polishing pad precursor B0. Was a cross section of the polishing pad B1 was observed with an electron microscope, the average the density _{D 1} of about 2450 pieces / mm ² of the microfine fiber bundles, average the density _{D 2} of the microfine fiber bundles from about 1260 / mm ² D ₁ / D ₂ was about 1.9. Further, in its cross-section, an average microfine fiber bundles of the cross-sectional area of about 325Myuemu ² of the average cross-sectional area consists of ultrafine fibers of about 12 [mu] m ² was observed. The ultrafine fibers were converged by the polyurethane elastic body that entered the ultrafine fiber bundle. The polishing pad B1 had a basis weight of 614 g / m ² , an apparent density of 0.58 g / cm ³ , a thickness of 1.06 mm, and a D hardness of 36. Then, 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 entangled web obtained in Example 1 was subjected to steam heating under the conditions of an atmospheric temperature of 80 ° C., a relative humidity of 80%, and 500 seconds. And only the surface was press-processed with the 120 degreeC hot roll with respect to the entangled web by which the steam heat processing was carried out. The area shrinkage ratio of the entangled web by the steam heat treatment and the press treatment was 50% in the dry state. Then, the treated entangled web was impregnated with an aqueous emulsion of polyurethane elastic body A having a solid concentration of 15% by mass. Next, the entangled web impregnated with the aqueous emulsion is coagulated in an atmosphere of 90 ° C. and 50% RH, and further dried at 150 ° C. to thereby entangle the entangled web and the polyurethane elastic body A. A complex was formed. The aqueous emulsion was impregnated in an amount of 7% by mass with respect to the total mass of the entangled web composite in terms of solid content of the polyurethane elastic body A. Then, the PVA resin is dissolved and removed by immersing the entangled web composite in 95 ° C. hot water for 10 minutes, and further, the nonwoven fabric made of a fiber bundle of ultrafine fibers and the polyurethane elastic body A by drying. A complex was formed.

And the nonwoven fabric composite was further impregnated with an aqueous emulsion of polyurethane elastic body A adjusted to a solid content concentration of 25% by mass. The aqueous emulsion was impregnated in an amount of 15% by mass with respect to the total mass of the nonwoven fabric composite in terms of solid content of the polyurethane elastic body A. Next, the nonwoven fabric composite impregnated with the aqueous emulsion is coagulated in an atmosphere of 90 ° C. and 50% RH, further dried at 150 ° C., and further hot-pressed at 150 ° C., whereby a polishing pad precursor is obtained. C0 was obtained. The polishing pad precursor C0 had a basis weight of 790 g / m ² , an apparent density of 0.63 g / cm ³ , and a thickness of 1.25 mm. Moreover, the mass ratio of the nonwoven fabric and the polyurethane elastic body A was 80/20.

Then, the polishing pad precursor C0 was buffed and ground to obtain a flattened polishing pad C1. Was a cross section of the polishing pad C1 was observed with an electron microscope, the average the density _{D 1} of the microfine fiber bundle is about 2840 pieces / mm ^2, the average the density _{D 2} of the microfine fiber bundles from about 1890 cells / mm ² D ₁ / D ₂ was about 1.5. Further, in its cross-section, an average microfine fiber bundles of the cross-sectional area of about 325Myuemu ² of the average cross-sectional area consists of ultrafine fibers of about 13 .mu.m ² was observed. The ultrafine fibers were converged by the polyurethane elastic body that entered the ultrafine fiber bundle. The polishing pad C1 had a basis weight of 650 g / m ² , an apparent density of 0.63 g / cm ³ , a thickness of 1.03 mm, and a D hardness of 37. The resulting 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 web laminate having a total basis weight of 480 g / m ² was produced by stacking 12 spunbond sheets similar to those obtained in Example 1 by cross-wrapping. And the needle | hook breaking prevention oil agent was sprayed to the obtained web laminated body. Next, the web laminate is formed by using a needle number 42, a needle needle having one barb, and a needle number 42, a needle needle having six barbs in this order from the first surface side to a needle depth of 5 to Needle punch processing at a depth of 25 mm and a punch number of 1200 punch / cm ² , and needle punch processing at a needle depth of 0 to 10 mm from the second surface side and a punch number of 300 punch / cm ² It was done. The area shrinkage ratio of the web laminate by needle punching was 20%. By such a needle punching process, an entangled web having a basis weight of 560 g / m ² and a delamination strength of 9.0 kg / 2.5 cm was obtained.

The obtained entangled web was subjected to steam heating under conditions of an atmospheric temperature of 60 ° C., a relative humidity of 70%, and 500 seconds. And only the surface was press-processed with the hot roll of 110 degreeC with respect to the entangled web by which the steam heat processing was carried out. The area shrinkage ratio of the entangled web by the steam heat treatment and the press treatment was 35% in a dry state. Then, the treated entangled web was impregnated with an aqueous emulsion of polyurethane elastic body A having a solid concentration of 15% by mass. Next, the entangled web impregnated with the aqueous emulsion is coagulated in an atmosphere of 90 ° C. and 50% RH, and further dried at 150 ° C. to thereby entangle the entangled web and the polyurethane elastic body A. A complex was formed. The aqueous emulsion was impregnated in an amount of 7% by mass with respect to the total mass of the entangled web composite in terms of solid content of the polyurethane elastic body A. The resulting entangled web composite is immersed in hot water at 95 ° C. for 10 minutes to dissolve and remove the PVA resin, and then dried to form a nonwoven fabric made of a fiber bundle of ultrafine fibers and the polyurethane elastic body A. A nonwoven composite was formed.

And the nonwoven fabric composite was further impregnated with an aqueous emulsion of polyurethane elastic body A adjusted to a solid content concentration of 25% by mass. The aqueous emulsion was impregnated in an amount of 15% by mass with respect to the total mass of the nonwoven fabric composite in terms of solid content of the polyurethane elastic body A. Next, the nonwoven fabric composite impregnated with the aqueous emulsion is coagulated in an atmosphere of 90 ° C. and 50% RH, further dried at 150 ° C., and further hot-pressed at 150 ° C., whereby a polishing pad precursor is obtained. E0 was obtained. The polishing pad precursor E0 had a basis weight of 665 g / m ² , an apparent density of 0.53 g / cm ³ , and a thickness of 1.25 mm. Moreover, the mass ratio of the nonwoven fabric and the polyurethane elastic body A was 80/20.

Then, the polishing pad precursor E0 was buffed and ground to obtain a flattened polishing pad E1. Was a cross section of the polishing pad E1 was observed by an electron microscope, the average the density _{D 1} of about 2,300 / mm ² of the microfine fiber bundles, average the density _{D 2} of the microfine fiber bundles from about 540 / mm ² , D ₁ / D ₂ was about 4.3. Further, in its cross-section, an average microfine fiber bundles of the cross-sectional area of about 325Myuemu ² of the average cross-sectional area consists of ultrafine fibers of about 11 [mu] m ² was observed. The ultrafine fibers were converged by the polyurethane elastic body that entered the ultrafine fiber bundle. The polishing pad E1 had a basis weight of 559 g / m ² , an apparent density of 0.53 g / cm ³ , a thickness of 1.05 mm, and a D hardness of 34. 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 web laminate having a total basis weight of 480 g / m ² was produced by stacking 12 spunbond sheets similar to those obtained in Example 1 by cross-wrapping. And the needle | hook breaking prevention oil agent was sprayed to the obtained web laminated body. Next, the web laminate is punched at a needle depth of 10 to 15 mm from the first surface side and the second surface side using needle needles having a needle count of 42 and six barbs. A total of 1800 punches / cm ² of needle punching was performed under the condition of several 900 punches / cm ² . The area shrinkage rate of the web laminate by needle punching was 30%. By such a needle punching process, an entangled web having a basis weight of 600 g / m ² and a delamination strength of 11.0 kg / 2.5 cm was obtained. The following is the same conditions as in Example 1, and the entangled web is hydrothermally treated to dissolve and remove the PVA resin, impregnated with polyurethane elastic body A, and further hot pressed at 150 ° C. A polishing pad precursor F0 was obtained. The polishing pad precursor F0 had a basis weight of 740 g / m ² , an apparent density of 0.63 g / cm ³ , and a thickness of 1.17 mm. Moreover, the mass ratio of the nonwoven fabric and the polyurethane elastic body A was 87/13.

And polishing pad F1 planarized was obtained by carrying out the buffing grinding process of polishing pad precursor F0. Was a cross section of the polishing pad F1 was observed by an electron microscope, the average the density _{D 1} of the microfine fiber bundle of approximately 2550 cells are / mm ^2, is the mean the density _{D 2} of microfine fiber bundles of about 2340 pieces / mm ² , D ₁ / D ₂ was about 1.1. In addition, in the cross section, an ultrafine fiber bundle having an average cross section of about 350 μm ^{2 made} of ultrafine fibers having an average cross section of about 14 μm ² was observed. The ultrafine fibers are focused by a polyurethane elastic body that has entered the inside of the ultrafine fiber bundle, and the ultrafine fiber bundles are also bound by the polyurethane elastic body. The polishing pad F1 had a basis weight of 613 g / m ² , an apparent density of 0.63 g / cm ³ , a thickness of 0.98 mm, and a D hardness of 38. Then, 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 web laminate having a total basis weight of 480 g / m ² was produced by stacking 12 spunbond sheets similar to those obtained in Example 1 by cross-wrapping. And the needle | hook breaking prevention oil agent was sprayed to the obtained web laminated body. Next, the web laminate is formed by using a needle number 42, a needle needle having one barb, and a needle number 42, a needle needle having six barbs in this order from the first surface side to a needle depth of 5 to Needle punch processing is performed at a depth of 25 mm and a punch number of 1200 punch / cm ² , and needle punch processing is performed at a needle depth of 0 to 5 mm from the second surface side and a punch number of 300 punch / cm ^2. It was done. The area shrinkage ratio of the web laminate by needle punching was 20%. By such a needle punching process, an entangled web having a basis weight of 560 g / m ² and a delamination strength of 9.4 kg / 2.5 cm was obtained.

The obtained entangled web was subjected to steam heating under conditions of an atmospheric temperature of 60 ° C., a relative humidity of 70%, and 500 seconds. And only the surface was press-processed with the hot roll of 110 degreeC with respect to the entangled web by which the steam heat processing was carried out. The area shrinkage ratio of the entangled web by the steam heat treatment and the press treatment was 35% in a dry state. Then, the treated entangled web was impregnated with an aqueous emulsion of polyurethane elastic body A having a solid concentration of 15% by mass. Next, the entangled web impregnated with the aqueous emulsion is coagulated in an atmosphere of 90 ° C. and 50% RH, and further dried at 150 ° C. to thereby entangle the entangled web and the polyurethane elastic body A. A complex was formed. The aqueous emulsion was impregnated in an amount of 7% by mass with respect to the total mass of the entangled web composite in terms of solid content of the polyurethane elastic body A. Then, the PVA resin is dissolved and removed by immersing the entangled web composite in 95 ° C. hot water for 10 minutes, and dried to form a nonwoven fabric composite of a nonwoven fabric composed of fiber bundles of ultrafine fibers and a polyurethane elastic body A. Formed.

And the nonwoven fabric composite was further impregnated with an aqueous emulsion of polyurethane elastic body A adjusted to a solid content concentration of 25% by mass. The aqueous emulsion was impregnated in an amount of 15% by mass with respect to the total mass of the nonwoven fabric composite in terms of solid content of the polyurethane elastic body A. Next, the nonwoven fabric composite impregnated with the aqueous emulsion is coagulated in an atmosphere of 90 ° C. and 50% RH, further dried at 150 ° C., and further hot-pressed at 150 ° C., whereby a polishing pad precursor is obtained. G0 was obtained. The polishing pad precursor G0 had a basis weight of 665 g / m ² , an apparent density of 0.53 g / cm ³ , and a thickness of 1.25 mm. Moreover, the mass ratio of the nonwoven fabric and the polyurethane elastic body A was 80/20.

Then, the polishing pad precursor G0 was buffed and ground to obtain a flattened polishing pad G1. Was a cross section of the polishing pad G1 was observed by an electron microscope, the average the density _{D 1} is about 2400 / mm ² of the microfine fiber bundles, average the density _{D 2} of the microfine fiber bundles from about 400 / mm ² , D ₁ / D ₂ was about 6.0. Further, in its cross-section, an average microfine fiber bundles of the cross-sectional area of about 325Myuemu ² of the average cross-sectional area consists of ultrafine fibers of about 11 [mu] m ² was observed. The ultrafine fibers were converged by the polyurethane elastic body that entered the ultrafine fiber bundle. The polishing pad G1 had a basis weight of 559 g / m ² , an apparent density of 0.53 g / cm ³ , a thickness of 1.05 mm, and a D hardness of 34. The obtained polishing pad G1 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, a strand of sea-island type composite fiber discharged from the die was wound up at 3000 m / min to obtain a filament. Then, the obtained filament was crimped and cut to obtain a staple having a cut length of 30 mm. The obtained staple was needle punched under the same conditions as in Example 1. By such a needle punching process, a short fiber entangled nonwoven fabric having a basis weight of 600 g / m ² and a delamination strength of 7.5 kg / 2.5 cm was obtained. The area shrinkage rate of the sheet made of staples by needle punching was 25%. Using the obtained short fiber entangled nonwoven fabric instead of the entangled web, the short fiber entangled nonwoven fabric was subjected to hot water treatment under the same conditions as in Example 1 to dissolve and remove the PVA resin, and the apparent density 0. A nonwoven fabric of 35 g / cm ³ was obtained. When the PVA resin was dissolved and removed, the short fiber entangled non-woven fabric was greatly extended, so that the ultrafine fibers were frequently removed. And the polishing pad precursor H0 was obtained by impregnating the polyurethane elastic body A to the obtained nonwoven fabric, and also heat-pressing at 150 degreeC. The polishing pad precursor H0 had a basis weight of 480 g / m ² , an apparent density of 0.43 g / cm ³ , and a thickness of 1.15 mm. Moreover, the mass ratio of the nonwoven fabric and the polyurethane elastic body A was 87/13.

Then, the polishing pad precursor H0 was buffed and ground to obtain a flattened polishing pad H1. Was a cross section of the polishing pad H1 observed with an electron microscope, the average the density _{D 1} of about 350 / mm ² of the microfine fiber bundles, average the density _{D 2} of the microfine fiber bundles from about 350 / mm ² , _{_D} 1 / _D ₂ was about 1.0. Further, in its cross-section, an average microfine fiber bundles of the cross-sectional area of about 350 .mu.m ² to average cross-sectional area consists of ultrafine fibers of about 16 [mu] m ² was observed. The ultrafine fibers were converged by the polyurethane elastic body that entered the ultrafine fiber bundle. The polishing pad H1 had a basis weight of 397 g / m ² , an apparent density of 0.42 g / cm ³ , a thickness of 0.95 mm, and a D hardness of 27. The obtained polishing pad H1 was processed in the same manner as in Example 1. Note that the evaluation of the polishing was omitted because the ultra-fine fibers were frequently loosened due to the large elongation of the short fiber entangled nonwoven fabric.

[Comparative Example 4]
In the same manner as in Example 1, a strand of sea-island type composite fiber discharged from the die was wound up at 3000 m / min to obtain a filament. Then, the obtained filament was crimped and cut to obtain a staple having a cut length of 30 mm. The obtained staple was needle punched under the same conditions as in Example 1. By such a needle punching process, a short fiber entangled nonwoven fabric having a basis weight of 600 g / m ² and a delamination strength of 7 kg / 2.5 cm was obtained. The area shrinkage ratio of the layer made of staples by needle punching was 25%.

The obtained short fiber entangled nonwoven fabric was subjected to steam heat treatment and press treatment under the same conditions as in Example 2. Then, under the same conditions as in Example 2, impregnating and imparting polyurethane elastic body A to the short fiber entangled nonwoven fabric after the treatment, dissolving and removing PVA resin, impregnating and imparting polyurethane elastic body A, drying and By performing hot pressing at 150 ° C., a polishing pad precursor I0 was obtained. The polishing pad precursor I0 had a basis weight of 730 g / m ² , an apparent density of 0.58 g / cm ³ , and a thickness of 1.25 mm. Moreover, the mass ratio of the nonwoven fabric and the polyurethane elastic body A was 80/20.

And polishing pad I1 planarized was obtained by carrying out the buffing grinding process of polishing pad precursor I0. Was a cross section of the polishing pad I1 was observed by an electron microscope, the average the density _{D 1} of about 1010 pieces / mm ² of the microfine fiber bundles, average the density _{D 2} of the microfine fiber bundles from about 930 cells / mm ² , D ₁ / D ₂ was about 1.1. Further, in its cross-section, an average microfine fiber bundles of the cross-sectional area of about 350 .mu.m ² to average cross-sectional area consists of ultrafine fibers of about 16 [mu] m ² was observed. The ultrafine fibers were converged by the polyurethane elastic body that entered the ultrafine fiber bundle. The polishing pad I1 had a basis weight of 613 g / m ² , an apparent density of 0.58 g / cm ³ , a thickness of 1.06 mm, and a D hardness of 35. Then, 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]
Isophthalic acid-modified PET strands were formed by discharging isophthalic acid-modified PET from a melt compound spinning die (die temperature 260 ° C.). Then, the strand discharged from the die was cooled while being stretched and thinned by an air jet suction device installed immediately below the die, thereby spinning an isophthalic acid-modified PET filament having an average fineness of 0.2 dtex. Then, the PET filament was continuously collected on a mobile net installed immediately below the air jet suction device to obtain a PET spunbond sheet (long fiber web) having a basis weight of 30 g / m ² .

Then, by stacking 12 sheets by cross lapping a spunbonded sheet obtained, the total basis weight was produced web laminate of 360 g / m ^2. And the nonwoven fabric was obtained by carrying out the needle punch process of the obtained web laminated body like Example 1. FIG. Then, the obtained nonwoven fabric was immersed in hot water at 70 ° C. for 90 seconds to relieve stress, thereby shrinking the area by 7%. The apparent density of such a hydrothermally treated nonwoven fabric was 0.25 g / cm ³ .

And the elastic pad precursor J0 was obtained by impregnating and giving the polyurethane elastic body A to the nonwoven fabric treated with hot water under the same conditions as in Example 1, and further hot pressing at 150 ° C. The polishing pad precursor J0 had a basis weight of 390 g / m ² , an apparent density of 0.25 g / cm ³ , and a thickness of 1.55 mm. Moreover, the mass ratio of a nonwoven fabric and the polyurethane elastic body A was 88/12.

Then, the polishing pad precursor J0 was buffed and ground to obtain a flattened polishing pad J1. When the cross section of the polishing pad J1 was observed with an electron microscope, ultrafine fibers having an average cross-sectional area of about 20 μm ² that did not form a fiber bundle were observed. The average existence density _{D 1} of the cross section of the ultrafine fibers is about 300 / mm ^2, the average the density _{D 2} of the cross section of the ultrafine fibers is about 300 / mm ^_2, the D 1 / _{D 2} About 1.0. 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. The resulting polishing pad J1 was processed in the same manner as in Example 1. In addition, polishing evaluation was abbreviate | omitted because the weight loss was large as a result of the weight loss measurement.

From the results in Table 1, all of the polishing pads of Examples 1 to 4 according to the present invention were excellent in polishing rate, polishing uniformity, wear resistance, planarization performance, 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, the polishing rate is excellent because of high rigidity, but the polishing uniformity is inferior because the followability is low, and Abrasion was also 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 because of low rigidity, and the followability was too high, resulting in poor planarization performance. Further, in the case of the polishing pads of Comparative Example 3 and Comparative Example 4 obtained using the sea-island type composite fiber staples, the fiber density could not be increased. Therefore, only a polishing pad with low rigidity was obtained, and the wear resistance was low. Further, in the case of the polishing pad of Comparative Example 5 obtained by using a non-woven fabric of ultrafine fibers directly formed by the spunbond method, it was not possible to increase the density of the fibers. Therefore, only a polishing pad with low rigidity was obtained, and the wear resistance was low.

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

DESCRIPTION OF SYMBOLS 1 Nonwoven fabric 1a Extra fine fiber 1b Extra fine fiber bundle 2 Polymer elastic body 3 Polishing surface (first surface)
4 Fixed surface (second surface)
10 thickness direction from the surface of the polishing pad R ₁ thickness region within 20% in the thickness direction from the thickness direction of 20% within the thickness region R ₂ surface of the fixing surface 4 from the surface of the polishing surface 3 R ₃ polished surface 3 40 to 60% thick region 11 Rotating surface plate 12 Slurry supply nozzle 13 Carrier 14 Pad conditioner 15 Substrate to be polished 16 Polishing slurry 20 CMP apparatus

Claims

A nonwoven fabric formed from a bundle of ultrafine fibers having an average cross-sectional area of 0.1 to 30 μm 2 , and a polymer elastic body provided inside the nonwoven fabric,
In longitudinal section in the thickness direction, in the thickness region within 20% in the thickness direction from the first surface, the average number density D 1 of the cross-section of said fiber bundle is 1000 to 5000 / mm 2,
D 1 and in the second thickness region within 20% from the surface in the thickness direction of the opposed to the first surface, the ratio between the average number density D 2 of the cross section of the fiber bundle (D 1 / D 2) A polishing pad having a thickness of 1.3 to 5.
The D 1 , the D 2, and the average number density D 3 of the cross section of the fiber bundle in a thickness region of 40 to 60% in the thickness direction from the first surface are D 1 > D 3 > D The polishing pad according to claim 1, wherein the relationship is two .
The polishing pad of claim 2 ratio of the D 1 and the D 3 (D 1 / D 3 ) is 1 to 1.4.
The polishing pad according to claim 2 or 3, wherein a ratio (D 3 / D 2 ) between the D 2 and the D 3 is 1.4 to 3.
The polishing pad according to any one of claims 1 to 4, wherein the D 2 is 200 to 3500 pieces / mm 2 .
The polishing pad according to any one of claims 1 to 5, wherein an average cross-sectional area of the fiber bundle is 40 to 400 µm 2 .
The polishing pad according to any one of claims 1 to 6, wherein the ultrafine fiber is a filament.
The polymer elastic body has a glass transition temperature of −10 ° C. or lower, storage elastic modulus at 23 ° C. and 50 ° C. is 90 to 900 MPa, and water absorption when saturated water absorption at 50 ° C. is 0.2. The polishing pad according to any one of claims 1 to 7, wherein the polishing pad is -5% by mass.
The polishing pad according to any one of claims 1 to 8, wherein a mass ratio (nonwoven fabric / polymer elastic body) between the nonwoven fabric and the polymer elastic body is 95/5 to 55/45.
The polishing pad according to any one of claims 1 to 9, wherein the D hardness of the first surface is 25 to 50.
The polishing pad according to any one of claims 1 to 10, wherein an adhesive tape for adhering to the polishing surface plate is attached to the second surface.
A chemical mechanical polishing method for a substrate,
A chemical mechanical polishing method in which polishing is performed by bringing the first surface of the polishing pad according to any one of claims 1 to 11 into contact with the surface of the substrate while dripping the polishing slurry onto the surface of the substrate. .