JP5222626B2 - Polishing pad and method of manufacturing polishing pad - Google Patents

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 flattened by the mechanical polishing action by the abrasive grains in the slurry and the 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 provided with 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). The surface of the obtained polyurethane body is ground, or the polyurethane body is sliced into a sheet to produce a polishing pad having openings on the surface. In the polishing pad manufactured by these techniques, the slurry is held in the holes formed on the surface during polishing, so that the mechanical polishing action can be improved by the polishing process of the free abrasive grain method. It is difficult to improve the effective polishing action.

  On the other hand, in contrast to the loose abrasive method, a so-called fixed abrasive method polishing process using a polishing pad containing abrasive particles inside a polyurethane body is known. Is limited and the mechanical polishing action becomes insufficient, so that the polishing performance is lowered as compared with the free abrasive grain method. In order to solve this problem, a polishing pad is also known in which water-soluble alkali particles that chemically react with the processed surface of an object to be polished are contained together with abrasive grains. In this polishing pad, the alkaline component is eluted from the water-soluble alkali particles during polishing and the chemical polishing action can be improved. However, since the water-soluble alkali particles have hygroscopicity, the water is contained in the water-soluble alkali particles. Unexpected foaming is easily formed in the polyurethane body, and the foamed structure becomes non-uniform. For this reason, the size of the holes formed on the surface of the polishing pad varies and the polishing characteristics are deteriorated. In addition, the alkaline component elutes in a relatively short time during the polishing process, so the chemical polishing action can be improved and the polishing characteristics can be improved at the initial stage of the polishing process, but the effect should be maintained for a long time. Becomes difficult. In order to suppress the hygroscopicity of such water-soluble alkali particles and the easy elution of alkali components, a polishing pad is formed on the surface of the water-soluble alkali particles, and this is incorporated into the polyurethane body together with the abrasive grains. (See, for example, Patent Document 9). Moreover, in order to improve polishing efficiency, the technique of the polishing pad containing the solid catalyst which accelerates | stimulates the chemical reaction in the processed surface of a to-be-polished object is also disclosed (for example, refer patent document 10).

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 JP 2004-31772 A JP 2004-319609 A

  However, in the technique of Patent Document 9, since a protective film is formed on the surface of the water-soluble alkali particles, the alkali component can be eluted continuously, but unexpected foam formation in the polyurethane body is not eliminated. That is, although the protective film reduces the influence of water contained in the water-soluble alkali particles, foaming failure occurs even with a small amount of water, so that a huge foam having a diameter of about several hundred μm is formed in the polyurethane body. And the foamed structure becomes uneven. For this reason, since a large opening is formed on the surface of the polishing pad due to giant foaming, the abrasive grains cause secondary agglomeration, which causes scratches (scratches) and the like on the object to be polished. Similarly, the technique of Patent Document 10 is liable to cause foaming failure, and since a protective film is not formed on the surface of the solid catalyst, elution cannot be controlled and the polishing characteristics are likely to change. In this respect, in the techniques of Patent Documents 1 to 5, since hollow spherical fine particles are mixed, defective foaming can be suppressed, but the outer shell component may cause unexpected polishing defects as foreign matters. On the other hand, mechanical polishing and chemical polishing can be improved by increasing the amount of abrasive grains and the concentration of alkali components contained in the slurry. In this case, however, the slurry is modified (gelation). And agglomeration of abrasive grains is likely to occur. For this reason, it becomes difficult to make the dispersed state of abrasive grains uniform, and on the contrary, the polishing characteristics are lowered.

  An object of the present invention is to provide a polishing pad that can make a foamed structure uniform and maintain good polishing characteristics, and a method for manufacturing the polishing pad.

In order to solve the above problems, a first aspect of the present invention is a polishing pad provided with a polyurethane body, wherein the polyurethane body has a hollow shape having a hemispherical shape or a semi-polyhedral shape and having a resin outer shell. The fine particles are dispersed substantially uniformly, and the outer shell of the fine particles contains at least one component selected from an alkaline substance, an acid substance, an oxidizing agent, a pH adjuster and a chelating agent. And

In the first aspect, the hollow fine particles having a hemispherical shape or a semi-polyhedral shape and having a resin outer shell are dispersed substantially evenly, so that the foam structure of the polyurethane body can be made uniform and the outer structure can be made uniform. At least one component selected from alkaline substances, acid substances, oxidizing agents, pH adjusters and chelating agents contained in the shell is gradually released from the exposed outer shell as the polyurethane body is worn during polishing. Therefore, good polishing characteristics can be maintained.

In the first aspect, the alkaline substance can be an alkali metal hydroxide. At this time, the alkali metal hydroxide may be at least one selected from sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide. Further, abrasive particles may be further contained in the outer shell of the fine particles. Openings having an average opening diameter of 10 μm to 150 μm can be formed on the surface of the polyurethane body. Further, at least one component may be in a weight ratio of 5 parts to 50 parts with respect to 100 parts of the fine particles. The fine particles may be contained in a weight ratio of 5 parts to 50 parts with respect to 100 parts of the polyurethane body .

A second aspect of the present invention is a method for producing a polishing pad provided with a polyurethane body, wherein the polyurethane body has a hollow shape having a hemispherical shape or a semi-polyhedral shape and having a resin outer shell. In the method for producing a polishing pad, fine particles are dispersed substantially uniformly, and the outer shell of the fine particles contains at least one component selected from an alkaline substance, an acid substance, an oxidizing agent, a pH adjuster and a chelating agent. A preparation step for preparing an isocyanate group-containing compound, an active hydrogen compound, and the fine particles, respectively, and a mixed solution in which the isocyanate group-containing compound, the active hydrogen compound, and the fine particles prepared in the preparation step are mixed substantially uniformly. And a molding step of dry-molding a polyurethane body in which the fine particles are substantially uniformly dispersed from the mixed solution.

According to a third aspect of the present invention, there is provided a method for producing a polishing pad comprising a polyurethane body, wherein hollow fine particles having a hemispherical or semi-polyhedral shape and having a resin outer shell are contained in the polyurethane body. In the method for producing a polishing pad, wherein the outer shell of the fine particles contains at least one component selected from an alkaline substance, an acid substance, an oxidizing agent, a pH adjuster, and a chelating agent in the outer shell of the fine particles. A preparation step of preparing a mixed solution in which the containing compound, the active hydrogen compound, the organic solvent capable of dissolving the reaction product of the isocyanate group-containing compound and the active hydrogen compound, and the fine particles are mixed substantially uniformly; The mixture prepared in the preparation step is spread into a sheet, and the organic solvent is removed from the mixture to remove the organic particles in a substantially uniform manner. Characterized in that it comprises a forming step of forming a single body.

According to the present invention, the foamed structure of the polyurethane body can be made uniform by dispersing the hollow fine particles having a hemispherical shape or a semi-polyhedral shape and having a resin outer shell substantially evenly, and At least one component selected from alkaline substances, acid substances, oxidizing agents, pH adjusters and chelating agents contained in the shell is gradually released from the exposed outer shell as the polyurethane body is worn during polishing. Therefore, an effect that good polishing characteristics can be maintained 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 having a foam structure. 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 obtained by slicing a polyurethane molded body formed from a mixture of an isocyanate group-containing compound, an active hydrogen compound, and hollow fine particles 3 having openings formed in a resin outer shell. It is formed by surface grinding such as buffing. In other words, the polyurethane sheet 2 is formed by a reaction between an isocyanate group-containing compound and an active hydrogen compound, and the fine particles 3 are dispersed therein.

  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. Since the polyurethane sheet 2 is formed by slicing or surface grinding the polyurethane molded body, the fine particles 3 are cut and the apertures 4 are formed on the polishing surface P. The opening 4 formed in the polishing surface P has an average opening diameter adjusted to a range of 10 to 150 μm. The thickness of the polyurethane sheet 2 is set in the range of 1.3 to 2.5 mm. In the polyurethane sheet 2 containing such fine particles 3, the Shore A hardness is in the range of 10 to 90 degrees.

  As shown in FIG. 2, the fine particles 3 have a hemispherical shape, and an opening is formed in a resin outer shell 3a. The fine particle 3 has a hollow recess 3b formed at the center. In other words, the fine particles 3 have a bowl shape in which hollow spherical fine particles are substantially divided into two, and the open end face of the outer shell 3a is exposed in an annular shape. The fine particles 3 are adjusted so that the outer diameter (particle diameter) of the opening end face of the outer shell 3a is in the range of about 10 to 150 μm. Air bubbles are held in the depressions 3b of the fine particles 3 dispersed in the polyurethane sheet 2, and the polyurethane sheet 2 is formed in a foamed shape.

  In addition, the fine particles 3 contain, in the outer shell 3a, polishing components 5a and abrasive particles (abrasive grains) 5b that chemically react with the object to be polished and contribute to the polishing process. Since the outer shell 3a is made of resin, the polishing component 5a and the abrasive particles 5b are not directly exposed to the outside on the surface of the fine particles 3 (the outer surface, the inner surface, and the opening end surface of the outer shell 3a). Then, a cross section in which the fine particles 3 located in the vicinity of the surface are cut by slicing or surface grinding of the polyurethane molded body is exposed. The polishing component 5 a is contained in the fine particles 3 so that the weight ratio is 5 to 50 parts with respect to 100 parts of the fine particles 3. The abrasive particles 5b are contained in the fine particles 3 so as to have a weight ratio of 1 to 30 parts with respect to 100 parts of the fine particles 3.

  As the polishing component 5a, at least one component selected from an alkaline substance, an acid substance, an oxidizing agent, a pH adjusting agent, and a chelating agent is used. In consideration of the inclusion of the polishing component 5a in the outer shell 3a of the fine particles 3, the polishing component 5a is preferably solid at room temperature, and more preferably in the form of a powder having an average particle size of 1 μm or less. Moreover, as the abrasive particles 5b, inorganic compound particles or organic compound particles can be used. Examples of the inorganic compound particles include particles of silica, alumina, cerium oxide, titanium oxide, chromium oxide, manganese dioxide, dimanganese trioxide, iron oxide, zirconium oxide, silicon carbide, boron carbide, diamond, barium carbonate, and the like. be able to. Examples of the organic compound particles include particles such as a styrene copolymer, a (meth) acrylic resin, an acrylic copolymer, a polyolefin resin, and an olefin copolymer. At the time of polishing, the chemical polishing action can be improved by releasing the polishing component 5a, and the mechanical polishing action can be improved by releasing the abrasive particles 5b, thereby improving the polishing rate. Can be made.

  Examples of the alkaline substance include alkali metal hydroxides, and it is preferable that the alkaline substance is granular or gel and water-soluble. Examples of the alkali metal hydroxide include potassium hydroxide, sodium hydroxide, rubidium hydroxide, cesium hydroxide and the like. The acid substance may be either an organic acid or an inorganic acid. For example, p-toluenesulfonic acid, dodecylbenzenesulfonic acid, isoprenesulfonic acid, gluconic acid, lactic acid, citric acid, tartaric acid, malic acid, glycol Organic acids such as acid, malonic acid, formic acid, oxalic acid, succinic acid, fumaric acid, maleic acid and phthalic acid, and inorganic acids such as nitric acid, hydrochloric acid and sulfuric acid can be used. Alkali substances and acid substances also act as pH adjusters.

  The oxidizing agent is not particularly limited as long as it is water-soluble. For example, organic peroxides such as hydrogen peroxide, peracetic acid, perbenzoic acid, tert-butyl hydroperoxide, permanganic acid compounds, dichromic acid compounds , Transition metal salts such as halogen acid compounds, nitrate compounds, perhalogen acid compounds, potassium ferricyanide, salts of polyvalent metals such as persulfates, iron nitrate, cerium ammonium nitrate, silicotungstic acid, phosphotungstic acid, silicomolybdic acid Further, heteropolyacids such as phosphomolybdic acid can be used.

  Examples of the pH adjuster include sodium dihydrogen phosphate, trisodium phosphate, tetrasodium pyrophosphate, disodium dihydrogen pyrophosphate, sodium tripolyphosphate, sodium polyphosphate, trimetaline, in addition to the alkali substances and acid substances described above. Sodium phosphate, sodium hexametaphosphate, sodium ultraphosphate, potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, tetrapotassium pyrophosphate, potassium polyphosphate, potassium metaphosphate, ammonium dihydrogen phosphate, phosphoric acid Diammonium hydrogen, calcium dihydrogen phosphate, calcium monohydrogen phosphate, tricalcium phosphate, monosodium fumarate, and the like can be used.

  As the chelating agent, for example, when the object to be polished is a semiconductor device or the like, any chelating agent can be used as long as it forms a chelate compound with the metal constituting the film to be processed on the polishing surface. Examples of chelating agents include oxalic acid, malonic acid, glycolic acid, citric acid, tartaric acid, ethylenediamine, diethylenetriamine, glycine, alanine, serine, aspartic acid, ethylenediaminetetraacetic acid, nitrilotriacetic acid, hydroxyethylidene diphosphonic acid, nitrilotris ( Methylenephosphonic acid), pyrophosphoric acid, triphosphoric acid and the like.

  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. Moreover, when the prepolymer used has a too high viscosity, the fluidity is deteriorated 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. 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 having openings formed in the outer shell 3a containing the polishing component 5a and the abrasive particles 5b 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, the silanol group-forming silicon compound, the silanol group-forming compound, the polishing component 5a and the abrasive particles 5b are mixed and brought into contact with water in the presence of a catalyst to hydrolyze the silanol group-forming silicon compound and the silanol group-forming compound. Decomposes 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 fine particles 3 having openings formed in the outer shell 3b made of an organic silicone resin containing the polishing component 5a and the polishing particles 5b. As a catalyst for the condensation reaction, a catalyst used for hydrolysis can be used. The generated fine particles 3 are dehydrated by a centrifugal separation method, a pressure filtration method, or the like and dried by heating. However, by performing a separation process, variation in size is reduced and the particle size (outer diameter of the opening end face of the outer shell 3a) is reduced. The range can be adjusted.

(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. When the fine particles 3 are mixed and dispersed in the active hydrogen compound, bubbles are held in the recesses 3b. 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 holding the bubbles in the recess 3b 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 is biased. 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. 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. Since bubbles are held in the depressions 3b of the fine particles 3, the fine particles 3 can easily move during molding. However, the cross-linking and curing around the fine particles 3 causes the uneven distribution of the fine particles 3 in the polyurethane molded body. Is suppressed.

(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 fine particles 3 are contained in a substantially uniform and substantially uniform dispersed state is obtained in the curing molding process, when a plurality of polyurethane sheets 2 are formed in the sheet forming process, the pores formed on the surface 4 has an average aperture diameter 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. Since the polishing surface P comes into contact with the slurry, and the polishing component 5a and the polishing particles 5b contained in the fine particles 3 (outer shell 3a) are eluted or released due to abrasion of the polishing surface P accompanying the polishing process. The processed surface of the object to be polished is polished by the polishing action of the supplied slurry and the polishing components 5a and abrasive particles 5b eluted or released from the polishing pad 1. 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 and 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. The liquid mixture prepared in the mixing step is applied substantially uniformly to the sheet base material by a coating device 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. Inside the obtained polyurethane molded product, the fine particles 3 are contained in a foamed state in a state of being dispersed substantially uniformly and substantially uniformly.

  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. Due to this buffing treatment, the thickness variation of the polyurethane molded body is eliminated, and an opening 4 in which fine particles 3 contained 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 according to the present embodiment will be described.

  In the polishing pad 1 of the present embodiment, the fine particles 3 are dispersed substantially uniformly and substantially uniformly in the polyurethane sheet 2, and the fine particles 3 (outer shell 3a) contain polishing components 5a and abrasive particles 5b. For this reason, the fine particles 3 are cut and the openings 4 are formed on the polished surface P, but a part of the outer shell 3a remains in the polyurethane sheet 2, and the cross section of the outer shell 3a is the polished surface P. Exposed. At the time of polishing, the polishing surface P side of the polyurethane sheet 2 is worn. Further, in order to improve the polishing efficiency, a dressing process for roughening the polishing surface P is performed on the polishing surface P side. On the polishing surface P, the outer shell 3a is gradually scraped by abrasion or dressing, so that the polishing component 5a and the abrasive particles 5b contained in the outer shell 3a are gradually eluted or released. As a result, the eluted or released polishing component 5a and abrasive particles 5b have a polishing action on the processed surface of the object to be polished together with the polishing liquid (slurry) supplied from the outside, so that polishing characteristics such as polishing efficiency and polishing accuracy can be achieved. 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 outer shell 3a of the fine particles 3 is successively exposed to the polishing surface P by the thickness of the polyurethane sheet 2 by the abrasion or dressing process on the polishing surface P side and scraped. For this reason, since the polishing component 5a and the abrasive particles 5b contained in the outer shell 3a are stably eluted or released, stable and good polishing characteristics can be maintained for a long time. Further, since the fine particles 3 are dispersed in a weight ratio of 5 to 50 parts with respect to 100 parts of the polyurethane sheet 2, the ratio of the openings 4 formed in the polishing surface P is adjusted. Thereby, since the slurry from the outside, the polishing component 5a from the fine particles 3, and the polishing particles 5b are held in the apertures 4 during the polishing process, the polishing characteristics 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 is shaved during the polishing process, the outer shell component (in this example, an organic silicone resin) is released between the polishing pad 1 and the object to be polished as compared with the case where conventional spherical fine particles are contained. ) Amount can be reduced. Thereby, the polishing failure caused by the outer shell component as a foreign substance can be reduced, and the polishing characteristics can be improved.

  Furthermore, in the polishing pad 1 of this embodiment, since the polishing component 5a and the polishing particles 5b are contained in the fine particles 3, the mechanical polishing action and the chemical polishing action on the object to be polished can be improved. Among the polishing components 5a, an alkali metal hydroxide can be expected to greatly improve the chemical polishing action, but it contains moisture because it has hygroscopicity. When this moisture reacts with the isocyanate group of the prepolymer when the polyurethane sheet 2 is molded, carbon dioxide gas is generated, so that extremely large foam is formed as compared with the size of the fine particles 3. In this embodiment, since the polishing component 5a is contained in the outer shell 3a, the polishing component 5a is protected by the resin that forms the outer shell 3a. For this reason, even if moisture is contained in the polishing component 5a, the reaction with the isocyanate group of the prepolymer is suppressed, so that formation of extremely large foam can be avoided and the foam structure of the polyurethane sheet 2 can be made uniform. In addition, since the bubbles are held in the depressions 3b of the fine particles 3, the fine particles 3 are dispersed substantially uniformly and substantially uniformly in the polyurethane molded body, so that the foam structure can be made uniform.

  Furthermore, in the first and second manufacturing methods of the polishing pad 1 shown in the present embodiment, the polishing component 5a contained in the fine particles 3 is in a weight ratio of 5 to 50 parts with respect to 100 parts by weight of the fine particles 3. Although it is set, it is difficult to increase it quantitatively considering the particle size of the fine particles 3. In the polishing process using the polishing pad 1, the polishing component 5a is gradually released in the vicinity of the polishing surface P as the polishing surface P is worn or dressed, so that a sufficient effect (polishing action) can be obtained even in a small amount. be able to. It is difficult to increase the content of the abrasive particles 5b in the fine particles 3, but a sufficient effect can be obtained by being released to the vicinity of the polishing surface P. Further, it is possible to add the abrasive component 5a and abrasive particles 5b contained in the fine particles 3 to the slurry. In this case, however, the proportion of alkali components and abrasive particles in the slurry is increased, and the slurry is modified. (Gelation) or agglomeration of abrasive particles. In the present embodiment, the proportion of alkali components and the like in the slurry can be reduced by the amount contained in the fine particles 3, so that denaturation and aggregation can be suppressed and the slurry can be stabilized.

  Furthermore, in the first and second manufacturing methods shown in the present embodiment, the fine particles 3 are adjusted to an average particle size of 10 to 150 μm. For this reason, air bubbles are held substantially uniformly in the recesses 3b, and the foamed structure of the polyurethane molded body can be made uniform. Thereby, the opening 4 can be easily formed so that an average 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.

  In the first manufacturing method shown in the present embodiment, a plurality of polyurethane sheets 2 can be formed from a polyurethane molded body. Since the polyurethane molded body contains the fine particles 3 substantially uniformly and substantially uniformly, in the plurality of polyurethane sheets 2, the difference in average pore diameter of the apertures 4 formed on the respective surfaces and the (apparent) density 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. Further, since the proportion of the space occupied by the fine particles 3 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.

  Furthermore, 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 fine particles 3 contain the polishing component 5a and the polishing particles 5b. . For this reason, the polishing component 5a and the abrasive particles 5b are gradually eluted or released by abrasion or dressing on the polishing surface P side during polishing processing, so that the polishing efficiency and the polishing accuracy can be improved and the effect is stabilized. Can be sustained. 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 the present embodiment, an example is shown in which the fine particles 3 (outer shell 3a) contain the abrasive component 5a and abrasive particles 5b, and examples of the abrasive component 5a include an alkaline substance, an oxidizing agent, an acid substance, a pH adjuster, and a chelating agent. However, the present invention is not limited to these, and for example, it is possible to further contain a component that contributes to polishing processing such as a cationic or anionic surfactant. Moreover, although the hydroxide of alkali metals, such as potassium hydroxide and sodium hydroxide, was illustrated as an alkaline substance of polishing component 5a, this invention will not be restrict | limited especially if it is a water-soluble alkaline substance. For example, instead of particles, a gel-like (swelled) water-soluble alkaline substance may be contained. Of course, the abrasive particles 5b are not limited to the exemplified inorganic compound particles and organic compound particles. Further, in the present embodiment, the example in which the polishing component 5a and the polishing particle 5b are mixed and contained in the fine particles 3 is shown, but the present invention is not limited to this. For example, the fine particles 3 containing the abrasive component 5a and the abrasive particles 5b separately may be prepared, and the respective fine particles 3 may be contained in the polyurethane sheet 2.

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 the fine particles 3 containing the abrasive component 5a and the abrasive particles 5b can be formed in the outer shell 3a, and the outer shell 3a is not limited to the organic silicone resin. Needless to say. Further, in the present embodiment, the microparticles 3 is an example of a semi-spherical, the present invention is not limited thereto and may be a semi-polyhedral shape instead of the semi-spherical. 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 present embodiment, an example in which the fine particles 3 are mixed with an active hydrogen compound in the first manufacturing method and an example in which the fine particle 3 is mixed with a polyurethane resin solution in the second manufacturing method are shown. However, the present invention is not limited to this. For example, before mixing the fine particles 3 with the active hydrogen compound or the polyurethane resin solution, it is possible to hold the polishing component (liquid) exemplified as the polishing component 5a in the recess 3b by immersing in the polishing liquid. . In this case, the bubbles in the recess 3b can be replaced with the polishing liquid by immersing the fine particles 3 in the polishing liquid under reduced pressure. In this way, the fine particles 3 are dispersed in the polyurethane sheet 2 while holding the polishing liquid in the depressions 3b, and the polishing liquid is released from the depressions 3b during the polishing process, so that the polishing characteristics can be further improved. . Further, a surfactant effective for suppressing aggregation of slurry (particularly abrasive particles) may be held in the recess 3.

  Furthermore, in the first manufacturing method shown in this embodiment, the example in which the fine particles 3 are mixed with the active hydrogen compound in advance in the mixing step to form 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. Further, in the mixing step, the fine particles 3 may be mixed alone as the third component. In this case, in order to make the dispersion state uniform, the fine particles 3 are dispersed in an organic solvent such as DMF, for example. It is preferable.

  Moreover, in the 1st manufacturing method shown by this embodiment, although the isocyanate terminal urethane prepolymer which made the polyol compound and the diisocyanate compound react was illustrated as a prepolymer, this 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.

  Furthermore, 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.

  Furthermore, 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 this. 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 the present 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.

  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 during polishing and the discharge of polishing debris. . 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.

  Furthermore, although not specifically mentioned in the present embodiment, 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. The fine particles 3 contain an abrasive component 5a and abrasive particles 5b in the outer shell portion 3a. 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)
In Example 2, 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 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 not containing polishing component 5a and polishing particles 5b were used. That is, the polishing pad of Comparative Example 1 is a conventional polishing pad. The particle size of the spherical fine particles was set in the range of 10 to 150 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 spherical fine particles not containing the polishing component 5a and the polishing particles 5b were dispersed, the average pore diameter on the polishing surface P was 9.5 μm, and the polyurethane sheet The Shore A hardness was 73.2 degrees and the density was 0.649 g / cm ³ . On the other hand, in the polishing pad 1 of Example 1 and Example 2 in which the fine particles 3 containing the polishing component 5a and the polishing particle 5b were dispersed, the average pore diameters were 9.5 μm and 9.3 μm, respectively. . From this, it was found that even if the abrasive component 5a and the abrasive particles 5b were contained, there was no difference in the size of the holes. Moreover, in the polyurethane sheet 2 of Example 1 produced by the first production method, the Shore A hardness was 73.3 degrees and the density was 0.639 g / cm ³ , whereas it was produced by the second production method. The polyurethane sheet 2 of Example 2 showed a Shore A hardness of 65.5 degrees and a density of 0.663 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. For comparison, a polishing process using distilled water was similarly performed without using slurry, 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 of the aluminum substrate, and the specific gravity. Moreover, the presence or absence of the scratch was determined visually. The measurement results of the polishing rate and scratch 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, the polishing pad of Comparative Example 1 showed a polishing rate of 0.197 μm / min when using silica slurry, while polishing the aluminum substrate when using distilled water. I could not. On the other hand, in the polishing pad 1 of Example 1 and Example 2 in which the fine particles 3 containing the polishing component 5a and the polishing particles 5b are dispersed, the polishing rate is 0.231 μm / min by using silica slurry, respectively. It was found that the improvement was 0.230 μm / min. In addition, it was found that in the polishing pads 1 of Examples 1 and 2, the aluminum substrate can be polished by using distilled water instead of silica slurry. Further, it was confirmed that the polishing pads 1 of Example 1 and Example 2 were able to obtain the same polishing performance even when repeated polishing was performed. From this, it was found that by incorporating the polishing component 5a and the polishing particles 5b into the fine particles 3, sufficient polishing performance can be obtained even when no slurry is used, and the polishing efficiency and the polishing accuracy can be maintained for a long time. Further, in the polishing pad of Comparative Example 1, clogging of the opening was recognized relatively early when the polishing process was repeated. On the other hand, the polishing pad 1 of Example 1 and Example 2 was able to perform polishing without clogging the opening 4 for a longer time than Comparative Example 1. From this, it was found that making the fine particles 3 hemispherical is effective in suppressing clogging.

  The present invention contributes to the manufacture and sales of polishing pads in order to provide a polishing pad that can make a foamed structure uniform and maintain good polishing characteristics, and a method for manufacturing the polishing pad. Have.

It is sectional drawing which shows the polishing pad of embodiment to which this invention is applied. It is a perspective view showing typically particulates contained in a polishing pad of an 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 3a Outer shell 3b Recess 4 Open hole 5a Polishing component 5b Abrasive particle

Claims (9)

In the polishing pad provided with the polyurethane body, hollow fine particles having a hemispherical shape or a semi-polyhedral shape and having a resin outer shell are dispersed substantially uniformly in the polyurethane body. A polishing pad comprising at least one component selected from an alkaline substance, an acid substance, an oxidizing agent, a pH adjusting agent and a chelating agent.   The polishing pad according to claim 1, wherein the alkaline substance is an alkali metal hydroxide.   The polishing pad according to claim 2, wherein the alkali metal hydroxide is at least one selected from sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.   The polishing pad according to claim 1, wherein the fine particles further contain abrasive particles in the outer shell.   2. The polishing pad according to claim 1, wherein the polyurethane body has openings having an average opening diameter of 10 μm to 150 μm formed on a surface thereof.   The polishing pad according to claim 1, wherein the at least one component is in a weight ratio of 5 to 50 parts with respect to 100 parts of the fine particles.   The polishing pad according to claim 1, wherein the fine particles are dispersed in a weight ratio of 5 to 50 parts with respect to 100 parts of the polyurethane body. A method for producing a polishing pad comprising a polyurethane body, wherein hollow fine particles having a hemispherical shape or a semi-polyhedral shape and having a resin outer shell are dispersed substantially uniformly in the polyurethane body. In the method for producing a polishing pad, the outer shell contains at least one component selected from an alkaline substance, an acid substance, an oxidizing agent, a pH adjuster and a chelating agent.
A preparation step of preparing an isocyanate group-containing compound, an active hydrogen compound, and the fine particles;
A molding step of preparing a mixed liquid in which the isocyanate group-containing compound, active hydrogen compound and fine particles prepared in the preparing step are substantially uniformly mixed, and dry-molding a polyurethane body in which the fine particles are substantially uniformly dispersed from the mixed liquid. When,
The manufacturing method characterized by including. A method for producing a polishing pad comprising a polyurethane body, wherein hollow fine particles having a hemispherical shape or a semi-polyhedral shape and having a resin outer shell are dispersed substantially uniformly in the polyurethane body. In the method for producing a polishing pad, the outer shell contains at least one component selected from an alkaline substance, an acid substance, an oxidizing agent, a pH adjuster and a chelating agent.
A preparation step for preparing a mixed solution in which 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 the fine particles are mixed substantially uniformly. When,
A step of spreading the mixed solution prepared in the preparation step into a sheet, and removing the organic solvent from the mixed solution to form a polyurethane body in which the fine particles are dispersed substantially uniformly;
The manufacturing method characterized by including.

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