JP2009279680A - Method of manufacturing polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad capable of uniforming foaming structure. <P>SOLUTION: The polishing pad 1 has a polyurethane sheet 2 of the foaming structure. The polyurethane sheet 2 includes an isocyanate-group containing compound as a main component, and has a polishing surface P to abut to a polished object via slurry in the polishing process. Hemispherical particulates 3 with resin shells are approximately regularly and evenly dispersed on the polyurethane sheet 2. A hollow cavity is formed at the center of each shell, and a foaming component is disposed in the cavity of the particulate 3. Pores 6 formed of the foaming component disposed in cavities of the particulates 3 are approximately regularly and evenly formed in the polyurethane sheet 2. The particulates 3 are enclosed in the pores 6. The pores 6 are formed of gases generated from the foaming component. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polishing pad and a method for manufacturing the polishing pad, and more particularly to a polishing pad provided with a polyurethane body and a method for manufacturing the polishing pad.

  Since flatness is required on the surface of materials (objects to be polished) such as semiconductor device manufacturing and glass substrates for liquid crystal displays, polishing using a polishing pad is performed. In semiconductor devices, as the degree of integration of semiconductor circuits increases rapidly, miniaturization and multilayer wiring for the purpose of higher density have progressed, and techniques for flattening the polished surface have become important. On the other hand, with a glass substrate for a liquid crystal display, higher flatness of the surface is required as the liquid crystal display becomes larger.

  In general, a chemical mechanical polishing (hereinafter abbreviated as CMP) method is used for manufacturing a semiconductor device. In the CMP method, a so-called free abrasive grain method is generally employed in which a slurry (polishing liquid) in which abrasive grains (polishing particles) are dispersed in an alkaline solution is supplied during polishing. That is, the object to be polished (the processed surface thereof) is polished by a mechanical polishing action by the abrasive grains in the slurry and a chemical polishing action by the alkaline solution. With the advancement of flatness required for the processed surface, polishing characteristics such as polishing accuracy and polishing efficiency required for the CMP method, in other words, performance required for the polishing pad is also increasing.

  In the CMP method, a polishing pad having a polyurethane body is widely used. In the production of such a polishing pad, a polyurethane body having a foam structure is usually formed by curing an isocyanate group-containing compound (prepolymer) and an active hydrogen compound (curing agent) by reaction. In order to form a foamed structure, for example, a technique for mixing hollow spherical fine particles having a resin outer shell (see Patent Documents 1 to 5), a technique for adding water (see Patent Document 6), an inert gas, and the like (See Patent Document 7) and a technique for mixing water-soluble fine particles (see Patent Document 8). By polishing the surface of the obtained polyurethane body or by slicing the polyurethane body into a sheet, a polishing pad having an opening formed on the surface (polishing surface) is produced. In the polishing pad manufactured by these techniques, the slurry is held in the opening formed in the polishing surface during the polishing process, so that the object to be polished can be polished by the free abrasive grain method.

Japanese Patent No. 3013105 Japanese Patent No. 3425894 Japanese Patent No. 3801998 JP 2006-186394 A JP 2007-184638 A JP 2005-68168 A Japanese Patent No. 3455208 JP 2000-34416 A

  However, in the techniques of Patent Documents 6 to 7, although pores are formed on the surface by water or an inert gas, the diameter of the polyurethane body is about several hundreds μm due to the reaction of moisture with the isocyanate groups of the prepolymer. There is a risk that the foaming structure may become non-uniform. In the technique of Patent Document 8, water-soluble fine particles are eluted by slurry to form pores. However, it is not easy to uniformly disperse the water-soluble fine particles in the polyurethane body, and the pore diameter tends to be non-uniform. Further, since the water-soluble fine particles easily bring in moisture, huge foam is formed in the polyurethane body, and the foam structure may be nonuniform. Therefore, the polishing pad according to these techniques deteriorates the polishing characteristics because large openings due to giant foaming are formed on the polishing surface of the polishing pad and the sizes of the openings vary. In addition, the supplied abrasive grains cause secondary agglomeration within the apertures, which may cause scratches or the like on the processed surface of the object to be polished, thereby reducing flatness. In this regard, in the techniques of Patent Documents 1 to 5, since hollow spherical fine particles are mixed, poor foaming can be suppressed, but when the hollow spherical fine particles do not open on the polished surface, the hardness of the hollow spherical fine particles May not be reduced, and the outer shell component may cause an unexpected polishing failure as a foreign substance, thereby reducing the flatness of the object to be polished.

  An object of the present invention is to provide a polishing pad capable of making the foamed structure uniform and a method for manufacturing the polishing pad in view of the above-described case.

  In order to solve the above-described problems, a first aspect of the present invention is a polishing pad provided with a polyurethane body, wherein the polyurethane body includes hollow resin fine particles having a hemispherical or semi-polyhedral outer shell. The pores are formed by a foaming component disposed in the hollow portion of the resin fine particles.

  In the first aspect, the polyurethane resin has pore-shaped pores formed by the foamed components disposed in the hollow portions of the resin fine particles in which hollow resin fine particles having a hemispherical or semi-polyhedral outer shell are substantially uniformly dispersed inside. Therefore, the foam structure of the polyurethane body can be made uniform.

  In the first aspect, if the surface of the polyurethane body is ground and an opening is formed on the surface, the retention of the polishing liquid can be ensured and the flatness of the object to be polished can be improved. Further, the foaming component may be at least one selected from a chemical foaming agent that is solid at normal temperature and generates gas at 100 ° C. to 260 ° C., a water-soluble substance holding water, and water. At this time, the chemical blowing agent is selected from barium azodicarboxylate, N, N′-dinitrosopentamethylenetetramine, sodium hydrogen carbonate, azodicarbonamide, 4,4′-oxybisbenzenesulfonylhydrazide and hydrazodicarbonamide. It is good also as 1 type or 2 types or more. Moreover, it is preferable to make a foaming component into the weight ratio of 5 parts-50 parts with respect to 100 parts of resin fine particles. The average pore diameter of the pores formed on the surface of the polyurethane body can be 10 μm to 150 μm. It is preferable that the resin fine particles are dispersed in a weight ratio of 5 parts to 50 parts with respect to 100 parts of the polyurethane body.

  According to a second aspect of the present invention, there is provided a method for producing a polishing pad comprising a polyurethane body, wherein the polyurethane body has hollow resin fine particles having a hemispherical or semi-polyhedral outer shell substantially uniformly inside. In the method of manufacturing a polishing pad dispersed in the pores of the foamed component disposed in the hollow portion of the resin fine particles, an isocyanate group-containing compound, an active hydrogen compound, and the resin fine particles in which the foamed component is disposed in the hollow portion Preparing a mixed solution in which the isocyanate group-containing compound, active hydrogen compound and resin fine particles prepared in the preparatory step are mixed substantially uniformly, and the resin fine particles are dispersed from the mixed solution. And a molding step of dry-molding a polyurethane body having pores formed by a foaming component.

  The third aspect of the present invention is a method for producing a polishing pad comprising a polyurethane body, wherein the polyurethane body has hollow resin fine particles having a hemispherical or semi-polyhedral outer shell inside. In a method for producing a polishing pad, which is substantially uniformly dispersed and has pores formed by a foaming component disposed in a hollow portion of the resin fine particles, an isocyanate group-containing compound, an active hydrogen compound, the isocyanate group-containing compound, and the active hydrogen compound A preparation step of preparing a mixed solution in which an organic solvent capable of dissolving the reaction product of the above and a resin fine particle in which the foaming component is disposed in a hollow portion are mixed substantially uniformly, and a mixed solution prepared in the preparation step. Polyureta which is spread in a sheet shape, and the organic solvent is removed from the mixed solution to disperse the resin fine particles and to form pores by the foamed component. Characterized in that it comprises a step of forming the body, the.

  According to the present invention, the hollow resin fine particles having a hemispherical or semi-polyhedral outer shell are dispersed in the polyurethane body substantially evenly, and pores are formed by the foaming component disposed in the hollow portion of the resin fine particles. Therefore, the effect that the foamed structure of the polyurethane body can be made uniform can be obtained.

  Hereinafter, embodiments of a polishing pad to which the present invention is applied will be described with reference to the drawings.

(Polishing pad)
As shown in FIG. 1, the polishing pad 1 has a polyurethane sheet 2 as a polyurethane body. The polyurethane sheet 2 contains an isocyanate group-containing compound as a main component, and has a polishing surface P that comes into contact with a surface to be polished (processed surface) of an object to be polished through a slurry (polishing liquid) during polishing. The polyurethane sheet 2 is a mixture of an isocyanate group-containing compound, an active hydrogen compound, and fine particles (resin fine particles) 3 having a hollow shape having a hemispherical resin outer shell and a foaming component disposed in the hollow portion. It is formed by subjecting a polyurethane molded body formed from a liquid to surface grinding treatment such as slicing and buffing.

  The inside of the polyurethane sheet 2 contains (internally adds) the fine particles 3 in a state of being dispersed substantially uniformly and substantially uniformly. The content of the fine particles 3 is set to a weight ratio of 5 to 50 parts with respect to 100 parts of the polyurethane sheet 2. Due to the foaming component disposed in the hollow portion of the fine particles 3, the pores 6 are formed substantially uniformly and substantially uniformly inside the polyurethane sheet 2. For this reason, the polyurethane sheet 2 has a foamed structure. Since the pores 6 are formed by the foaming component disposed in the hollow portion of the fine particles 3, the fine particles 3 are enclosed in the pores 6. FIG. 1 shows a state in which the microparticles 3 are encapsulated in only one pore 6, and the encapsulated microparticles 3 are omitted in the remaining pores 6.

  As shown in FIG. 2, the fine particles 3 are made of a resin and have a hemispherical outer shell 3a, and a hollow recess 3b is formed at the center. In other words, the fine particles 3 have a bowl-like shape in which hollow spherical fine particles are roughly divided into two to form openings. The fine particles 3 are adjusted so that the outer diameter (particle diameter) of the opening portion is in the range of about 10 to 150 μm. The fine particles 3 are provided with a foaming component 5 that generates gas and forms pores in forming the polyurethane molded body in the depression 3b. The foaming component 5 is held in the depression 3b at a weight ratio of 5 to 50 parts with respect to 100 parts of the fine particles 3. If the amount of the foaming component 5 is too small, the formation of pores is insufficient. Conversely, if the amount is too large, the size of the formed pores 6 tends to vary. In other words, the foaming component 5 is adjusted to an amount required to form the pores 6 having the same size as that of the fine particles 3.

  As shown in FIG. 1, since the polyurethane sheet 2 is formed by slicing or surface grinding a polyurethane molded body, the opening 4 in which pores 6 are formed in the polishing surface P is formed. The opening 4 is formed with an average opening diameter in the range of 10 to 150 μm because the pores 6 formed by the foaming component 5 are formed to have almost the same size as the particle diameter of the fine particles 3. The thickness of the polyurethane sheet 2 is set in the range of 1.3 to 2.5 mm. In the polyurethane sheet 2 in which such pores 6 are formed, the Shore A hardness is in the range of 10 to 90 degrees.

  The foaming component 5 includes at least one component selected from a chemical foaming agent that is solid at room temperature and thermally decomposes at 100 ° C. to 260 ° C. to generate a decomposition gas, a water-soluble substance holding water, and water. It is used. During the formation of the polyurethane molded body, the pores 6 are formed by gas generated by decomposition or vaporization of the foam component 5.

  As the chemical foaming agent, for example, selected from barium azodicarboxylate, N, N′-dinitrosopentamethylenetetramine, sodium hydrogen carbonate, azodicarbonamide, 4,4′-oxybisbenzenesulfonylhydrazide and hydrazodicarbonamide 1 type, or 2 or more types can be used. If the thermal decomposition temperature of the chemical foaming agent is less than 100 ° C, it will be difficult to equalize and homogenize the dispersed state of the pores at the early stage of formation of the polyurethane molded product. Even if a body is formed, it does not decompose and pores 6 are not formed.

  Examples of the water-soluble substance include water-soluble polysaccharides such as carboxymethyl cellulose, hydroxypropyl cellulose, carboxymethyl chitin, dextrin, and cyclodextrin and derivatives thereof, oligosaccharides such as chitooligosaccharide, fructooligosaccharide, sucrose, and glucose. Monosaccharides, potassium hydroxide, sodium hydroxide, rubidium hydroxide, cesium hydroxide, potassium acetate, potassium nitrate, potassium carbonate, potassium hydrogen carbonate, potassium chloride, potassium bromide, potassium phosphate, aliphatic amine salts, Cationic systems such as aliphatic ammonium salts, anionic systems such as alkylbenzene sulfonates, sulfonates, alkyl ether sulfates, and phosphate ester salts, and nonionic interfaces such as ether, ether ester, and ester types Sexual agents, amino acids and proteins, polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl sulfonic acid, and polyacrylic acid. Since these water-soluble substances easily retain moisture, the moisture retained in the water-soluble substance during the formation of the polyurethane molded body reacts with the isocyanate group-containing compound to generate gas and form pores 6.

  As shown in FIG. 1, the polishing pad 1 has a double-sided tape for attaching the polishing pad 1 to a polishing machine on the surface opposite to the polishing surface P of the polyurethane sheet 2. The double-sided tape has an adhesive layer (not shown) on both surfaces of a base material 7 such as a polyethylene terephthalate (hereinafter abbreviated as PET) film. Examples of the adhesive for the adhesive layer include acrylic adhesives. The double-sided tape is bonded to the polyurethane sheet 2 with an adhesive layer on one side, and the adhesive layer on the other side is covered with a release paper 8.

(Manufacture of polishing pad)
The polishing pad 1 can be manufactured by two manufacturing methods. That is, a first manufacturing method in which a mixed liquid obtained by mixing an isocyanate group-containing compound, an active hydrogen compound, and fine particles 3 is poured into a mold and cured in the mold, or an isocyanate group-containing compound, an active hydrogen compound, and fine particles 3 And a mixed solution in which an organic solvent capable of dissolving a reaction product of an isocyanate group-containing compound and an active hydrogen compound is applied onto a sheet-like substrate, and the solvent is removed while heating. The polishing pad 1 can be manufactured using the polyurethane sheet 2. Hereinafter, the first manufacturing method and the second manufacturing method will be described in this order.

(First manufacturing method)
In the first manufacturing method, the polishing pad 1 is manufactured through the steps shown in FIG. That is, a preparation step (preparation step) for preparing an isocyanate group-containing compound, an active hydrogen compound, and fine particles 3 respectively, and a mixing step (molding) for preparing a mixed liquid in which the isocyanate group-containing compound, the active hydrogen compound, and the fine particles 3 are mixed. Part of the step), casting process for casting the mixed liquid into the mold (part of the molding step), curing molding process for forming the polyurethane molding in the mold (part of the molding step), polyurethane molding Are manufactured through a sheet forming process for forming a polyurethane sheet 2 by slicing and surface grinding, and a laminating process for bonding the polyurethane sheet 2 and a double-sided tape. Hereinafter, it demonstrates in order of a process.

(Preparation process)
In the preparation step, an isocyanate group-containing compound, an active hydrogen compound, and fine particles 3 are prepared. As an isocyanate group-containing compound to be prepared, an isocyanate-terminated urethane prepolymer (hereinafter, referred to as “polyisocyanate-terminated urethane prepolymer”) produced by reacting a polyol compound having two or more hydroxyl groups in the molecule with a diisocyanate compound having two isocyanate groups in the molecule. Simply abbreviated as prepolymer). When the polyol compound and the diisocyanate compound are reacted, the prepolymer can be obtained by making the molar amount of the isocyanate group larger than the molar amount of the hydroxyl group. In addition, if the prepolymer has a too high viscosity, the fluidity becomes poor and it becomes difficult to mix substantially uniformly during mixing. When the viscosity is lowered by increasing the temperature, the pot life is shortened (the curing reaction of the prepolymer is accelerated). On the other hand, mixed spots are generated and the dispersion state of the fine particles 3 is varied. Moreover, the foaming component 5 foams due to the temperature rise, and the size of the pores 6 and the dispersion state may vary. On the other hand, if the viscosity is too low, the fine particles 3 move in the mixed solution, and it becomes difficult to disperse the fine particles 3 substantially uniformly and substantially uniformly in the obtained polyurethane molded body. For this reason, it is preferable that a prepolymer sets the viscosity in the temperature of 50-80 degreeC in the range of 500-4000 mPa * s. For example, the viscosity can be set by changing the molecular weight (polymerization degree) of the prepolymer. The prepolymer is heated to about 50 to 80 ° C. to be in a flowable state.

  Examples of the diisocyanate compound used for producing the prepolymer include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate (2,6-TDI), 2,4-tolylene diisocyanate (2,4- TDI), naphthalene-1,4-diisocyanate, diphenylmethane-4,4′-diisocyanate, 3,3′-dimethoxy-4,4′-biphenyl diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, Xylylene-1,4-diisocyanate, 4,4′-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, Rohekishiren 1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p- phenylenediisothiocyanate, xylylene-1,4-diisothiocyanate, mention may be made of ethylidyne diisothiocyanate like. Two or more of these diisocyanate compounds may be used in combination.

  On the other hand, the polyol compound used for producing the prepolymer may be a compound such as a diol compound or a triol compound. For example, a low molecular weight polyol compound such as ethylene glycol or butylene glycol, and polytetramethylene glycol (PTMG). Polyether polyol compounds such as, a reaction product of ethylene glycol and adipic acid, a polyester polyol compound such as a reaction product of butylene glycol and adipic acid, a polycarbonate polyol compound, a high molecular weight polyol compound such as a polycaprolactone polyol compound, etc. Can be used. Two or more of these polyol compounds may be used in combination.

  The active hydrogen compound only needs to have an active hydrogen group that reacts with the terminal isocyanate group of the prepolymer, and a polyamine compound or a polyol compound can be used. The active hydrogen compound reacts with the isocyanate group of the prepolymer to form a hard segment (a urethane bond portion that imparts rigidity at a high melting point). Examples of the polyamine compound include ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4′-diamine, 3,3′-dichloro-4,4′-diaminodiphenylmethane (hereinafter abbreviated as MOCA). And polyamine compounds having the same structure as MOCA. Further, the polyamine compound may have a hydroxyl group, and examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, and di-2-hydroxy. Examples include ethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine. On the other hand, the polyol compound may be a compound such as a diol compound or a triol compound. For example, a low molecular weight polyol compound such as ethylene glycol or butylene glycol, a polyether polyol compound such as polytetramethylene glycol, or ethylene glycol. And a high molecular weight polyol compound such as a polyester polyol compound, a polycarbonate polyol compound, a polycaprolactone polyol compound, etc., such as a reaction product of adipic acid and a reaction product of butylene glycol and adipic acid. As the active hydrogen compound, at least one of a polyamine compound and a polyol compound may be used, and two or more of a polyamine compound or a polyol compound may be used in combination.

  The fine particles 3 in which the foaming component 5 is arranged in the depression 3b can be formed as follows, for example. In this example, the outer shell 3a is formed of an organosilicone resin by using a silanol group-forming silicon compound or a silanol group-forming compound that generates a silanol compound by hydrolysis. That is, a silanol group-forming silicon compound and a silanol group-forming compound are mixed and hydrolyzed by contacting with water in the presence of a catalyst to form a silanol compound. Examples of the catalyst that can be used include inorganic bases such as sodium hydroxide and potassium hydroxide, organic bases such as ammonia and trimethylamine, inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid and citric acid. The reaction solution containing the produced silanol compound is subsequently subjected to a condensation reaction to produce hollow fine particles 3 made of an organic silicone resin and having a hemispherical outer shell 3b. As a catalyst for the condensation reaction, a catalyst used for hydrolysis can be used. The produced fine particles 3 are dehydrated and dried by heating using a centrifugal separation method, a pressure filtration method, or the like. However, by performing a separation treatment, variation in size can be reduced and a range of particle diameters can be adjusted. The obtained fine particles 3 are immersed in a solution of the foaming component 5, stirred and mixed under reduced pressure, and then dried. By stirring under reduced pressure, the bubbles escape from the recess 3b, and the foam component 5 enters the recess 3b. By adjusting the particle diameter range of the fine particles 3, the size of the recess 3 b is formed to be substantially the same, so that the foaming component 5 is held in the recess 3 b in a small amount and with little variation in quantity. . In this example, a chemical foaming agent is used as the foaming component 5.

(Mixing process, casting process, curing molding process)
As shown in FIG. 3, in the mixing step, the prepolymer prepared in the preparation step, the active hydrogen compound, and the fine particles 3 are mixed to prepare a mixed solution. At this time, the fine particles 3 are mixed and dispersed in the active hydrogen compound substantially uniformly in advance in order to make the dispersion state in the mixed solution uniform. In the casting process, the liquid mixture prepared in the mixing process is cast into a mold, and in the curing molding process, the prepolymer and the active hydrogen compound are reacted and cured in the mold to mold a polyurethane molded body. In this example, a mixing process, a casting process, and a curing molding process are performed continuously.

  As shown in FIG. 4, in the mixing step, a mixed solution is prepared by the mixer 20, and in the casting step, the prepared mixed solution is continuously cast from the mixer 20 into the mold 25 and cured in the curing molding step. By doing so, a polyurethane molded body is molded. The mixer 20 includes a mixing tank 12 in which a stirring blade 14 is incorporated. On the upstream side of the mixing tank 12, a supply tank containing a prepolymer as a first component and an active hydrogen compound in which fine particles 3 are dispersed as a second component is disposed. The supply port from each supply tank is connected to the upstream end of the mixing tank 12. The stirring blade 14 is fixed to a rotating shaft arranged from the upstream side to the downstream side at a substantially central portion in the mixing tank 12. As the rotating shaft rotates, the stirring blade 14 rotates, and the first component and the second component are sheared and mixed. The obtained liquid mixture is poured into the mold 25 from a discharge port formed at the downstream end of the mixing tank 12. The upper part of the mold 25 is open, and in this example, the size is set to 1050 mm (length) × 1050 mm (width) × 50 mm (thickness). Since most of the prepolymer of the first component and the active hydrogen compound contained in the second component are both solid or difficult to flow at normal temperature, each supply tank is heated so that each component can flow. ing.

  The first component and the second component are supplied from the respective supply tanks to the mixing tank 12 and mixed by the stirring blade 14. By adjusting the mixing conditions in the mixer 20, that is, the shearing speed and the number of shearing of the stirring blade 14, the components are mixed substantially uniformly and substantially uniformly to prepare a mixed solution. If the shear rate of the stirring blade 14 is too low, the dispersed state of the fine particles 3 becomes non-uniform. On the other hand, if the shear rate is too high, the temperature rises due to heat generated by friction between the stirring blade 14 and the mixed solution, and the viscosity of the mixed solution decreases. For this reason, the fine particles 3 easily move during molding, and the dispersion state of the fine particles 3 in the polyurethane molded product varies. Moreover, the foaming component 5 foams due to the temperature rise, and the size and dispersion state of the pores 6 may become non-uniform. On the other hand, if the number of shears is too small, it is difficult to make the dispersion state of the fine particles 3 uniform. On the other hand, if the shear frequency is too large, the viscosity decreases due to the temperature rise and the dispersion state of the fine particles 3 varies. For this reason, in a mixing process, a shear rate is set to the range of 9,000-41,000 / sec, and the frequency | count of shear is set to the range of 300-10,000 times, and it mixes. The mixing time (residence time) in the mixer 20 is about 1 second although it depends on the flow rate of the mixed liquid (maximum 1 liter / sec). That is, for example, the time required to cast the mixed solution into the mold 25 of about 100 kg in the casting process is about 1 to 2 minutes. In addition, a shear rate and the frequency | count of shear can be calculated | required by following Formula. That is, shear rate (/ sec) = diameter (mm) of blade tip of stirring blade 14 × circularity × rotational speed (rpm) of stirring blade 14 ÷ 60 ÷ blade tip of stirring blade 14 and inner wall of mixing vessel 12 Clearance (mm), number of times of shearing (times) = rotation speed of stirring blade 14 (rpm) ÷ 60 × retention time of mixed solution in mixing tank 12 (second) × number of blades of stirring blade 14 Can do.

  When casting the mixed liquid into the mold 25 in the casting step, the mixed liquid from the mixer 20 is discharged from the discharge port of the mixing tank 12, and is disposed above the mold 25 through, for example, a flexible pipe. Liquid is introduced into a liquid inlet (not shown). The liquid injection port reciprocates between two sides facing each other in the length direction of the mold 25 (for example, between the left and right in FIG. 3), has a triangular cross section, and has a length in the width direction of the mold 25. . By moving the end of the discharge port (end of the flexible pipe) back and forth in the width direction of the mold 25 while reciprocating the liquid injection port in the length direction of the mold 25, the mixed liquid is transferred to the mold 25. It is cast almost evenly.

  In the curing molding process, the cast mixed liquid is reaction-cured in the mold 25 to mold a block-shaped polyurethane molded body. At this time, the prepolymer is crosslinked and cured by reaction with the active hydrogen compound. Since the upper part of the mold 25 is opened, the reaction (crosslinking curing) proceeds under atmospheric pressure, and a polyurethane molded body is molded. Further, the foaming component 5 arranged in the depression 3b of the fine particles 3 generates gas by the reaction heat generated by this reaction. Since the fine particles 3 are dispersed substantially uniformly and substantially uniformly in the mixed liquid, the pores 6 are formed substantially uniformly and substantially uniformly in the polyurethane molded body by the progress of crosslinking and curing around the fine particles 3. .

(Sheet formation process)
As shown in FIG. 3, in the sheet forming step, the polyurethane molded body obtained in the curing molding step is sliced into a sheet shape and subjected to surface grinding treatment such as buffing as necessary to form the polyurethane sheet 2. A general slicing machine can be used for slicing. At the time of slicing, the lower layer portion of the polyurethane molded body is held and sliced to a predetermined thickness in order from the upper layer portion. In this example, the thickness to be sliced is set in a range of 1.3 to 2.5 mm. In the polyurethane molded body molded with the mold 25 having a thickness of 50 mm used in this example, for example, about 10 mm of the upper layer portion and the lower layer portion of the polyurethane molded body is not used because of scratches, etc. 10 to 25 polyurethane sheets 2 can be formed from 30 mm. In order to improve the thickness accuracy of the polyurethane sheet 2, a surface grinding process such as buffing may be further performed. A general buffing machine can be used for buffing. Since a polyurethane molded body in which the pores 6 are formed substantially uniformly and substantially uniformly in the curing molding process is obtained, when a plurality of polyurethane sheets 2 are formed in the sheet forming process, the average of the openings 4 formed on the surface The opening diameter is in the range of 10 to 150 μm.

(Lamination process)
In the laminating process, the polyurethane sheet 2 formed in the sheet forming process and the double-sided tape are bonded together. After cutting into a desired shape and size such as a circle, an inspection such as confirming that there is no adhesion of dirt or foreign matter is performed to complete the polishing pad 1.

  When polishing an object to be polished, the polishing pad 1 is mounted on a polishing surface plate of a polishing machine. When the polishing pad 1 is mounted on the polishing surface plate, the release paper 8 is removed, and the surface is adhered and fixed to the polishing surface plate with the exposed adhesive layer. By pressing the object to be polished held on the holding surface plate arranged to face the polishing surface plate to the polishing surface P side and rotating the polishing surface plate or holding surface plate while supplying slurry from the outside. The processed surface of the object to be polished is polished. The processed surface of the object to be polished is polished while the supplied slurry is held in the opening 4 formed in the polishing surface P. Normally, water is used as a medium for the polishing liquid, but an organic solvent such as alcohol can also be mixed.

(Second manufacturing method)
Next, the second manufacturing method will be described, but the description of the same steps and the same substances as those in the first manufacturing method described above will be omitted, and only different portions will be described.

  In the second manufacturing method, the polishing pad 1 is manufactured through the steps shown in FIG. That is, a preparation step (part of the preparation step) for preparing a polyurethane resin solution and fine particles 3 obtained by reacting a prepolymer and an active hydrogen compound in an organic solvent, and mixing the fine particles 3 in the polyurethane resin solution substantially uniformly and substantially uniformly. , A mixing step for preparing a dispersed liquid mixture (part of the preparation step), an application step for applying (spreading) the liquid mixture on a substrate having a substantially flat surface (part of the forming step), Desolvation process (part of the forming step) to remove the organic solvent to form polyurethane molded body, surface grinding process to surface the polyurethane molded body uniformly, surface grinding process It is manufactured through a laminating process in which the polyurethane sheet 2 obtained and the double-sided tape are bonded together.

  In the preparation step, a prepolymer, an active hydrogen compound, and an organic solvent capable of dissolving the polyurethane resin that is a reaction product of the prepolymer and the active hydrogen compound are mixed, and the prepolymer and the active hydrogen compound are reacted to react with the polyurethane resin solution. To prepare. In this example, N, N-dimethylformamide (hereinafter abbreviated as DMF) is used as the organic solvent. In the mixing step, the polyurethane resin solution and the fine particles 3 are mixed and stirred, and the fine particles 3 are dispersed so as to be in a substantially uniform dispersion state to prepare a mixed solution. For the preparation of the mixed solution, a general stirring device can be used.

  In the application step, the mixed solution is continuously applied to a belt-like sheet base material having a substantially flat surface. That is, the mixed solution prepared in the mixing step is applied substantially uniformly and substantially uniformly to the sheet base material with a coating apparatus at room temperature. In this example, a knife coater is used as the coating device. At this time, by adjusting the gap (clearance) between the knife coater and the sheet substrate, the coating thickness (coating amount) of the mixed solution is adjusted to be in the range of about 1.3 to 2.5 mm. A flexible film, a nonwoven fabric, a woven fabric, etc. can be used for a sheet base material. When using a non-woven fabric or woven fabric, in order to suppress the penetration of the polyurethane resin solution into the sheet base material during application of the polyurethane resin solution, before dipping in water or a DMF aqueous solution (mixed solution of DMF and water) or the like in advance. Processing (sealing) is performed. When a flexible film made of PET or the like is used as the sheet base material, pretreatment is not necessary because it does not have liquid permeability. Hereinafter, in this example, the sheet base material is described as a PET film.

  In the solvent removal step, the DMF as a solvent is removed by passing the sheet substrate coated with the mixed solution through a hot air dryer. When DMF removes the solvent from the mixed solution, a sheet-like polyurethane molded body is formed. Fine particles 3 are dispersed substantially uniformly and substantially uniformly inside the obtained polyurethane molded body, and the foamed component 5 disposed in the depressions 3b of the fine particles 3 generates gas by heating with a hot air dryer, thereby forming pores 6. Is done.

  In the surface grinding treatment step, the polyurethane molded body is peeled from the sheet base material, and surface grinding processing such as slicing and buffing is performed on the surface of the polyurethane molded body (surface not in contact with the sheet base material). In the case of buffing, the surface side of the polyurethane molded body is buffed while the surface of the pressure roller having a flat surface is pressed against the back surface (the surface in contact with the sheet substrate) of the polyurethane molded body. In this example, since the continuously manufactured polyurethane molded body is in a band shape, the surface is continuously buffed while pressing the pressing roller on the back surface. By this buffing treatment, the thickness variation of the polyurethane molded body is eliminated, and an opening 4 in which pores 6 formed therein are opened is formed on the buffed surface side. The surface where the opening 4 is formed (the surface subjected to the buffing process) becomes the polishing surface P. Instead of buff processing, slice processing can also be performed. The surface-treated polyurethane sheet 2 is wound into a roll.

(Action etc.)
Next, the operation and the like of the polishing pad 1 and the manufacturing method of the polishing pad 1 of this embodiment will be described.

  In the polishing pad 1 of this embodiment, the fine particles 3 are dispersed substantially uniformly and substantially uniformly in the polyurethane sheet 2, and the particle size of the fine particles 3 (outer diameter of the opening portion) is set in the above-described range. In addition, pores 6 are formed by the foamed component 5 disposed in the depressions 3 b of the fine particles 3. For this reason, since the pores 6 are formed by the amount of gas generated by the foaming component 5, the formation of giant foaming is suppressed and the foamed structure of the polyurethane sheet 2 can be made uniform. On the polishing surface P, an opening 4 in which pores 6 are formed is formed. At the time of polishing, the polishing surface P side of the polyurethane sheet 2 is worn, and the polishing surface P is roughened by dressing in order to improve polishing efficiency. When the polyurethane sheet 2 is worn due to wear or dressing, the pores 6 formed in the vicinity of the polishing surface P are opened, and the openings 4 are sequentially formed. As a result, the polishing liquid (slurry) supplied from the outside is polished while being held in the openings 4, so that the retention of the polishing liquid can be secured and the flatness of the object to be polished can be improved.

  Moreover, in the polishing pad 1 of this embodiment, the fine particles 3 are contained in the polyurethane sheet 2 substantially uniformly and substantially uniformly in a weight ratio of 5 to 50 parts with respect to 100 parts. For this reason, the pores 6 are formed substantially uniformly and substantially uniformly, and the ratio of the pores 6 formed inside the polyurethane sheet 2 and thus the ratio of the openings 4 formed in the polishing surface P are adjusted. Accordingly, since the slurry is supplied substantially evenly between the polishing pad 1 and the object to be polished during the polishing process, the flatness of the object to be polished can be improved. Furthermore, in the present embodiment, the fine particles 3 have a hemispherical shape. For this reason, even if the outer shell 3a exposed to the polishing surface P during the polishing process is scraped, the outer shell component released between the polishing pad 1 and the object to be polished (this example) compared to the case where conventional spherical fine particles are contained (this example) Then, the amount of the organic silicone resin) can be reduced. As a result, poor polishing caused by the outer shell component as a foreign substance can be reduced. In addition, when conventional spherical fine particles are contained, the spherical fine particles may not be opened on the polished surface, the hardness of the spherical fine particles does not decrease, and the outer shell component becomes a foreign substance, leading to unexpected polishing defects and being polished. Although the flatness of the object may be lowered, in the present embodiment, since the fine particles 3 are hemispherical, such a problem can be avoided.

  Furthermore, in the first and second manufacturing methods of the polishing pad 1 shown in the present embodiment, the foaming component 5 disposed in the depression 3b of the fine particles 3 is 5 to 50 parts with respect to 100 parts by weight of the fine particles 3. Set to weight percentage. By disposing in the depression 3b, the foaming component 5 can be made in a very small amount and the quantitative variation can be reduced. For this reason, even if the foaming component 5 generates gas, the size of the pores 6 formed is limited. Further, when the pores 6 are formed, the hardening of the pores 6 is suppressed because the curing and molding is proceeding by a crosslinking curing reaction or a desolvation reaction. Thereby, since the size of the pores 6 is made uniform and the size of the openings 4 formed by the openings of the pores 6 is made uniform, the slurry supply between the polishing pad 1 and the object to be polished is equalized, The flatness of the object to be polished can be improved.

  Furthermore, in the first and second manufacturing methods shown in the present embodiment, the particle diameter of the fine particles 3 is adjusted to 10 to 150 μm. For this reason, since the pores 6 formed by the foaming component 5 disposed in the recess 3b are substantially spherical and are formed with the same size as the particle diameter of the fine particles 3, the foamed structure of the polyurethane molded body can be made uniform. it can. Thereby, the opening 4 can be easily formed so that the opening diameter becomes substantially uniform. Therefore, at the time of polishing, the retention of the slurry is ensured and clogging is suppressed, so that the polishing efficiency and the polishing accuracy can be improved. In addition, the formation of agglomerates such as abrasive particles is suppressed by preventing clogging without forming extremely large apertures, improving flatness without causing scratches on the workpiece. Can be made.

  Furthermore, in the first manufacturing method shown in this embodiment, a plurality of polyurethane sheets 2 can be formed from a polyurethane molded body. Since the pores 6 are formed substantially uniformly and substantially uniformly in the polyurethane molded body, the difference in the average aperture diameter of the apertures 4 formed on the respective surfaces and the (apparent) density of the plurality of polyurethane sheets 2. Any difference can be within a range of ± 3% of the average value. When the variation in the aperture diameter becomes large, the aperture 4 is likely to be locally clogged by abrasive grains (abrasive particles), polishing debris, etc. in the slurry during polishing, and the flatness of the object to be polished is lowered. Further, since the hardness becomes too small (soft) when the density is reduced, it is difficult to improve the flatness of the object to be polished. On the contrary, if the density is increased, the hardness becomes too high, so that the polishing efficiency is lowered and the object to be polished is easily damaged. In the present embodiment, since the average opening diameter of the openings 4 is equal between the plurality of polishing pads 1, any of them can suppress local clogging. In addition, since the proportion of the space occupied by the pores 6 in each polishing pad 1 is equal and the hardness is also equal, even if the polishing pad 1 is replaced, it is possible to suppress variation in polishing performance.

  In the second manufacturing method shown in the present embodiment, the polyurethane sheet 2 is formed by mixing the fine particles 3 with the polyurethane resin solution and removing the solvent. For this reason, the polyurethane sheet 2 which has the softness | flexibility comparable to the polyurethane sheet obtained by the wet film-forming method which substitutes the organic solvent of a polyurethane resin solution with the poor solvent water with respect to a polyurethane resin can be obtained. Further, it is difficult to contain the fine particles 3 by the wet film forming method, but the fine particles 3 can be easily contained in the polyurethane sheet 2.

  As described above, in the polishing pad 1 of the present embodiment, the fine particles 3 are dispersed substantially uniformly and substantially uniformly inside the polyurethane sheet 2, and the pores 6 are formed by the foamed component 5 disposed in the depressions 3 b of the fine particles 3. Are formed substantially uniformly and substantially uniformly. For this reason, the size and dispersion state of the apertures 4 formed in the polishing surface P during the polishing process are made uniform and uniform, so that it is possible to secure slurry retention and improve the flatness of the object to be polished. The effect can be maintained stably. The polishing pad 1 using such a polyurethane sheet 2 is extremely useful as a polishing pad for CMP (Chemical Mechanical Polishing) using a semiconductor device or the like as an object to be polished.

  In addition, in this embodiment, although the example which distributes the foaming component 5 to the hollow 3b of the microparticle 3 was shown and the chemical foaming agent was illustrated as the foaming component 5, this invention is not limited to these. For example, a water-soluble substance holding water or water itself can be disposed in the recess 3b. The fine particles 3 in which the water-soluble substance is arranged in the depression 3b are obtained by, for example, immersing the fine particles 3 in an aqueous solution of the water-soluble substance, stirring and mixing under reduced pressure, and then drying to a state where appropriate moisture remains. It is done. In addition, the fine particles 3 in which the water itself is arranged in the depression 3b can be obtained, for example, by moistening the fine particles 3 in water and adjusting the water appropriately. Since water reacts with the isocyanate group of the prepolymer to generate gas, pores are formed in the same manner as when a chemical foaming agent is used. In addition, water itself may vaporize. Even in such a case, since the amount of water-soluble substances and water distributed to the fine particles 3 is limited, it is possible to avoid the formation of extremely large pores inside the polyurethane molded body and to make the foam structure uniform. Can do. Further, the size of the fine particles 3 and the blending ratio of the foaming component 5 are not particularly limited, and may be prepared in consideration of the gas generation amount of the foaming component 5.

  In the present embodiment, an example in which the organosilicone resin fine particles 3 are formed by condensation reaction of a silanol compound is shown, but the present invention is not limited thereto. Any method can be used as long as it can form the hemispherical fine particles 3, and the outer shell 3a is not limited to the organic silicone resin. Furthermore, in the present embodiment, the example in which the fine particles 3 are hemispherical is shown, but the present invention is not limited to this, and may be a semipolyhedral instead of the hemispherical. For example, fine particles obtained by dividing particles on a hollow hexahedron or hollow octahedron can be used. Of course, the shape of the recess 3b is not limited in any shape.

  Further, in the present embodiment, the polishing pad 1 using the sheet-like polyurethane sheet 2 as the polyurethane body is exemplified, but the present invention is not limited to this, and a block shape or a belt can be used in accordance with the polishing method. It is also possible to form a polishing pad. For example, the block-shaped polyurethane molded product shown in the first production method of the present embodiment may be used for polishing as it is, and the coating thickness of the polyurethane resin solution shown in the second production method is increased. Also good. In such a case, the opening 4 can be formed by subjecting the surface side to surface grinding.

  Furthermore, in the first manufacturing method shown in the present embodiment, the example in which the fine particles 3 are mixed with the active hydrogen compound in advance in the mixing step as the second component is shown, but the present invention is limited to this. Instead, it can also be mixed with the prepolymer and used as the first component. In the mixing step, the fine particles 3 may be mixed alone as the third component, but in this case, it is preferable to disperse them in an organic solvent or the like in order to make the dispersion state uniform.

  Furthermore, in the first manufacturing method shown in the present embodiment, an isocyanate-terminated urethane prepolymer obtained by reacting a polyol compound and a diisocyanate compound is exemplified as the prepolymer, but the present invention is not limited to this. . For example, an active hydrogen compound having a hydroxyl group, an amino group or the like may be used instead of the polyol compound, and a polyisocyanate compound or a derivative thereof may be used instead of the diisocyanate compound, and these may be reacted. In addition, since various kinds of isocyanate-terminated prepolymers are commercially available, commercially available products can be used.

  Moreover, in the 1st manufacturing method shown by this embodiment, although the example which performs a mixing process, a casting process, and a hardening molding process continuously was shown, this invention is not restrict | limited to this, Each process May be performed independently. In the present embodiment, an example is shown in which casting is performed from the mixer 20 to the mold 25 and molding is performed under atmospheric pressure, but the present invention is not limited to this. For example, the liquid mixture may be prepared in a container and cured and molded in the container, or the container may be sealed and cured and molded under pressure.

  Further, in the first manufacturing method shown in the present embodiment, an example in which a plurality of polyurethane sheets 2 are obtained by slicing a block-like polyurethane molded body molded with the mold 25 is shown. It is not limited to. For example, the polyurethane sheet 2 may be molded one by one by applying the sheet 25 on a substrate having a flat surface without using the mold 25. In this case, the opening 4 can be formed by subjecting the surface side to surface grinding treatment such as slicing treatment or buffing treatment.

  Furthermore, in the second production method shown in this embodiment, an example in which a polyurethane resin solution is prepared by reacting an isocyanate group-containing compound and an active hydrogen compound in DMF has been shown. It is not limited. For example, a polyurethane resin such as polyester, polyether or polycarbonate may be dissolved in DMF.

  Further, although not particularly mentioned in the present embodiment, the polishing surface P of the polishing pad 1 may be subjected to grooving or embossing in consideration of the supply of slurry at the time of polishing and the discharge of polishing debris. Good. The shape of the groove may be any of a radial shape, a lattice shape, and a spiral shape, and the cross-sectional shape may be any of a rectangular shape, a U shape, a V shape, and a semicircular shape. The pitch, width, and depth of the grooves are not particularly limited as long as the polishing waste can be discharged and the slurry can be moved. When grooving is performed on the polishing pad, for example, if an opening having a large hole diameter is formed on the surface of the polishing pad, the opening and the groove overlap to form a protrusion-like corner, and therefore, the polishing pad is covered during polishing. Scratches will occur in the polished material. In the present embodiment, the openings 4 of the polishing pad 1 are substantially uniform with an average value of the diameter of 10 to 150 [mu] m, so that it is possible to suppress the generation of scratches on the object to be polished even when the grooves are formed.

  Further, in the present embodiment, although not particularly mentioned, for example, a cushion material may be interposed between the polyurethane sheet 2 and the double-sided tape. Further, when the polishing pad 1 is mounted on the polishing surface plate of the polishing machine, it may be mounted via a cushion material. By making the hardness of the cushion material smaller than that of the polyurethane sheet 2, it is possible to absorb unevenness of the polishing surface plate and the polishing pad, thickness unevenness due to mounting, etc., and make the polishing process of the object to be polished more uniform. If the base material 7 of the double-sided tape includes a nonwoven fabric or a low elasticity film, the base material 7 can also function as a cushioning material.

  Hereinafter, examples of the polishing pad 1 manufactured according to the present embodiment will be described. A comparative polishing pad manufactured for comparison is also shown.

Example 1
In Example 1, the polishing pad 1 was manufactured according to the first manufacturing method. In the production of the prepolymer, PTMG having an average molecular weight of about 2000 was used as the polyol compound, and 2,4-TDI and 2,6-TDI were mixed at a molar ratio of 7/3 as the diisocyanate compound. By reacting these, a prepolymer having a viscosity at a temperature of 50 ° C. of 5500 mPa · s and an NCO equivalent of 549 was obtained. This prepolymer was heated to 55 ° C. and degassed under reduced pressure. The active hydrogen compound of the second component was MOCA, dissolved at about 120 ° C. and degassed under reduced pressure. As the fine particles 3, an outer shell 3 a having an average particle diameter of 7 μm was formed of an organic silicone polymer, and a chemical foaming agent azodicarbonamide was disposed as the foaming component 5 in the recess 3 b. Prepolymer: MOCA: fine particles 3 were mixed in a weight ratio of 100 parts: 22.8 parts: 5.3 parts. In the mixing step, the stirring conditions were set to a shear rate of 1689 times and a shear rate of 9425 / second. The obtained mixed liquid was poured into a mold 25 and cured, and then the formed polyurethane molded body was extracted from the mold 25 and sliced to a thickness of 1.3 mm to prepare a polishing pad 1.

(Example 2, Example 3)
In Examples 2 and 3, the polishing pad 1 was produced in the same manner as in Example 1 except that the foaming component 5 was changed. As foaming component 5, Example 2 used carboxymethylcellulose in which moisture was retained, and Example 3 used water.

Example 4
In Example 4, the polishing pad 1 was manufactured according to the second manufacturing method. For the production of the polyurethane sheet 2, a polyester MDI (diphenylmethane diisocyanate) polyurethane resin was used as a polyurethane resin in which a prepolymer and an active hydrogen compound were reacted. To 100 parts of a polyurethane resin solution containing 30% by weight of this polyurethane resin, 5.3 parts of the fine particles 3 used in Example 1 were added and mixed to prepare a mixed solution. The mixed liquid was applied to the sheet base material to remove the solvent, and the polishing pad 1 of Example 2 was produced.

(Comparative Example 1)
In Comparative Example 1, a polishing pad of Comparative Example 1 was produced in the same manner as in Example 1 except that hollow spherical fine particles (Matsumoto Yushi Seiyaku Co., Ltd., Matsumoto Microbead M-610, cross-linked acrylic type) were used. That is, the polishing pad of Comparative Example 1 is a conventional polishing pad. The average particle size of the hollow spherical fine particles was set to 10 μm.

(Physical property measurement)
About the polishing pad 1 of each Example and the comparative example, the average hole diameter of the opening 4 and the Shore A hardness and density of the polyurethane sheet 2 were measured. The average aperture diameter was observed with a microscope (manufactured by KEYENCE, VH-6300) by enlarging the range of about 1.3 mm by 175 times, and the obtained image was image processing software (Image Analyzer V20LAB Ver. 1.3). ) And calculated. The Shore A hardness was measured by a method in accordance with Japanese Industrial Standard (JIS K 7311). The density was calculated from the volume obtained from the size of a sample cut into a predetermined size. The measurement results of average pore diameter, Shore A hardness and density are shown in Table 1 below.

As shown in Table 1, in the polishing pad of Comparative Example 1 in which hollow spherical fine particles were dispersed, the average pore diameter on the polishing surface P was 9.4 μm, the Shore A hardness of the polyurethane sheet was 74.9 degrees, and the density Of 0.635 g / cm ³ . On the other hand, in the polishing pad 1 of Examples 1 to 4 in which the fine particles 3 in which the foaming component 5 is arranged in the depression 3b are dispersed, the average pore diameter is 8.9 to 9.7 μm. From this, it was found that there is no difference in the size of the opening 4 in the polished surface P even in the polyurethane sheet 2 in which the pores 6 are formed by the foaming component 5. In any of the examples and comparative examples, formation of large pores exceeding several hundred μm was not confirmed. Moreover, in the polyurethane sheet 2 of Example 1-Example 3 produced with the 1st manufacturing method, Shore A hardness shows 72.8-75.2 degree and a density shows 0.628-0.654 g / cm < ³ >. In contrast, the polyurethane sheet 2 of Example 4 produced by the second production method showed a Shore A hardness of 64.9 degrees and a density of 0.659 g / cm ³ . From this, it was found that in the second production method in which the polyurethane sheet 2 is formed by solvent removal, the soft polyurethane sheet 2 can be obtained as compared with the first production method in which the prepolymer is cured.

(Polishing performance evaluation)
Next, using the polishing pad 1 of each Example and Comparative Example, the aluminum substrate for hard disk was polished under the following polishing conditions, and the polishing rate was measured. The polishing rate is the amount of polishing per minute expressed by thickness, and was calculated from the polishing amount obtained from the weight reduction of the aluminum substrate before and after polishing, the polishing area and specific gravity of the aluminum substrate. The measurement results of the polishing rate are shown in Table 2 below.
(Polishing conditions)
Polishing machine used: Speedfam, 9B-5P polishing machine Polishing speed (rotation speed): 30 rpm
Processing pressure: 100 g / cm ²
Slurry: Colloidal silica slurry (pH: 11.5)
Slurry supply amount: 100cc / min
Workpiece: Aluminum substrate for hard disk (outer diameter 95mmφ, inner diameter 25mm, thickness 1.27mm)

  As shown in Table 2, with the polishing pad of Comparative Example 1, the polishing rate was 0.185 μm / min, and scratches were also confirmed. On the other hand, in the polishing pad 1 of Examples 1 to 4 in which the hemispherical fine particles 3 in which the foaming component 5 is arranged in the depression 3b are dispersed, the polishing rate is 0.194 to 0.199 μm / min. Improved, and no scratch was observed. Further, when the polishing process was repeated, clogging of the opening was recognized relatively early in the polishing pad of Comparative Example 1, whereas clogging occurred in the polishing pad 1 of Examples 1 to 4. It was difficult to maintain the polishing performance for a long time. From this, it was found that making the fine particles 3 hemispherical is effective in suppressing clogging. Therefore, it has been found that by forming the pores 6 with the foaming component 5 disposed on the fine particles 3, sufficient polishing performance can be maintained for a long time.

  The present invention contributes to the manufacture and sale of polishing pads in order to provide a polishing pad and a method for manufacturing the polishing pad that can make the foam structure uniform, and thus has industrial applicability.

It is sectional drawing which shows the polishing pad of embodiment to which this invention is applied. It is a perspective view which shows typically the microparticles | fine-particles disperse | distributed to the polishing pad of embodiment. It is process drawing which shows the principal part of the 1st manufacturing method of the polishing pad of embodiment. It is a block diagram which shows the outline of the mixer and mold which were used with the 1st manufacturing method of the polishing pad. It is process drawing which shows the principal part of the 2nd manufacturing method of a polishing pad.

Explanation of symbols

1 Polishing pad 2 Polyurethane sheet (Polyurethane body)
3 Fine particles (resin fine particles)
3a outer shell 3b hollow (hollow part)
5 Foaming component 6 Pore

Claims (9)

  In the polishing pad provided with the polyurethane body, the polyurethane body has hollow resin fine particles having a hemispherical or semi-polyhedral outer shell dispersed therein substantially uniformly, and is disposed in the hollow portion of the resin fine particles. A polishing pad, wherein pores are formed by the foamed component.   2. The polishing pad according to claim 1, wherein a surface of the polyurethane body is ground and an opening is formed in the surface. 3.   The foaming component is at least one selected from a chemical foaming agent that is solid at room temperature and generates a gas at 100 ° C to 260 ° C, a water-soluble substance holding water, and water. 2. The polishing pad according to 1.   The chemical blowing agent is selected from barium azodicarboxylate, N, N′-dinitrosopentamethylenetetramine, sodium bicarbonate, azodicarbonamide, 4,4′-oxybisbenzenesulfonylhydrazide and hydrazodicarbonamide. The polishing pad according to claim 3, wherein the polishing pad is one type or two or more types.   The polishing pad according to claim 1, wherein the foaming component is in a weight ratio of 5 parts to 50 parts with respect to 100 parts of the resin fine particles.   The polishing pad according to claim 2, wherein the polyurethane body has an average pore diameter of 10 µm to 150 µm formed on the surface.   The polishing pad according to claim 1, wherein the resin fine particles are dispersed in a weight ratio of 5 parts to 50 parts with respect to 100 parts of the polyurethane body. A method for producing a polishing pad comprising a polyurethane body, wherein the polyurethane body has hollow resin fine particles having a hemispherical or semi-polyhedral outer shell dispersed therein substantially uniformly, and the resin fine particles are hollow. In the manufacturing method of the polishing pad in which pores are formed by the foaming component arranged in the part,
A preparation step of preparing an isocyanate group-containing compound, an active hydrogen compound, and resin fine particles in which the foaming component is arranged in a hollow part,
A polyurethane body in which the isocyanate group-containing compound, active hydrogen compound and resin fine particles prepared in the preparation step are mixed substantially uniformly to prepare a mixed liquid, and the resin fine particles are dispersed from the mixed liquid and pores are formed by the foaming component. A molding step for dry molding;
The manufacturing method characterized by including. A method for producing a polishing pad comprising a polyurethane body, wherein the polyurethane body has hollow resin fine particles having a hemispherical or semi-polyhedral outer shell dispersed therein substantially uniformly, and the resin fine particles are hollow. In the manufacturing method of the polishing pad in which pores are formed by the foaming component arranged in the part,
An isocyanate group-containing compound, an active hydrogen compound, an organic solvent capable of dissolving a reaction product of the isocyanate group-containing compound and the active hydrogen compound, and resin fine particles in which the foaming component is disposed in a hollow portion are substantially uniform. A preparation step for preparing a mixed liquid mixture;
A forming step of spreading the mixed solution prepared in the preparing step into a sheet shape, removing the organic solvent from the mixed solution, and dispersing the resin fine particles to form pores by the foamed component When,
The manufacturing method characterized by including.

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