JP2010023134A - Polishing pad - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polishing pad capable of optically detecting a polished state and improving polishing performance. <P>SOLUTION: The polishing pad 20 has a urethane sheet 2. The urethane sheet 2 has a polishing surface P for polishing a material to be polished. A hydrophilic resin region 3 for permitting a polishing liquid supplied during polishing to infiltrate over the whole thickness is formed on at least part of the urethane sheet 2. The sheet 2 is formed integrally with the hydrophilic resin region 3. Hollow fine particles 13 having a hemispherical resin-made shell are included inside the urethane sheet 2 containing the resin 3, and bubbles 5 are formed of the air provided in a recess of the particle 13. Infiltration of the polishing liquid into the hydrophilic region 3 causes the region 3 to exhibit light transmissivity, and apertures 6 are formed approximately uniformly on the polishing surface P. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polishing pad, and more particularly to a polishing pad provided with a resin polishing layer having a polishing surface for polishing an object to be polished.

  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 general, a chemical mechanical polishing (hereinafter abbreviated as CMP) method is used as a method for flattening a processed surface of a semiconductor device or the like. In the CMP method, a slurry (polishing liquid) in which abrasive grains (polishing particles) are dispersed in an alkali solution or an acid solution is supplied in a state in which a processed surface of an object to be polished is pressed against a polishing pad. The polishing pad used usually includes a resin polishing layer having a polishing surface for polishing an object to be polished. Polishing is performed by mechanical action by abrasive grains in the slurry and chemical action by an alkali solution or an acid solution. With the advancement of flatness required for the processed surface, the polishing accuracy required for the CMP method, in other words, the performance required for the polishing pad is also increasing.

  In such a polishing process, the processed surface of the object to be polished is polished with the minimum necessary to improve the flatness. For example, in the case of a semiconductor device or the like, there is a possibility that circuit wiring or the like may be damaged by excessive polishing, so that it is important to detect the end point (polishing end point) in polishing processing. Conventionally, the polishing end point is detected by interrupting the polishing process and inspecting the processed surface. However, this method requires cleaning and drying of the processed surface every time the polishing process is interrupted, which increases the polishing time and costs. Further, even if the interruption time is shortened, the polishing conditions are different before and after the interruption, so that there is a problem that the expected polishing amount cannot be obtained and the polishing efficiency is lowered. On the other hand, the polishing end point can be detected based on the polishing time. In this case, an average processing speed is obtained in advance from the thickness reduction amount of the object to be polished by the polishing process and the polishing time, and a standard polishing time until the polishing end point is determined in accordance with the desired polishing process amount. However, since the material and slurry of the object to be polished and the polishing apparatus are different, it is difficult to set a standard polishing time for all the combinations, which leads to a decrease in efficiency.

  Also known is a method of directly observing the state of the work surface of the object to be polished (polishing state) during polishing by an optical method and detecting the polishing end point. In this method, for example, a light-transmitting window for detecting a polishing end point is formed in at least a part of the polishing layer constituting the polishing pad, and light is emitted from the processing surface by irradiating the processing surface with light. The reflection state is observed to determine the polishing state. Therefore, the polishing end point can be detected in situ without interrupting the polishing process, and the time required for the polishing process can be shortened. As a method for optically detecting a polishing end point, for example, a technique of observing reflected light from a processing surface with an imaging device is disclosed (see Patent Document 1 and Patent Document 2). In addition, a technique using a transparent plug as a light transmitting portion of the polishing pad (for example, see Patent Document 3 and Patent Document 4), a technique for forming an opening in the polishing pad and overlaying a transparent sheet (for example, see Patent Document 5), light A technique using a hard and uniform resin sheet having transparency (see, for example, Patent Document 6 and Patent Document 7) is disclosed.

  However, in the techniques of Patent Literature 3, Patent Literature 4, and Patent Literature 5, except for the case where the light transmission portion is formed on the entire surface of the polishing layer, liquid leakage of the slurry is likely to occur between the polishing layer and the light transmission portion. There is a problem. If the liquid leaks, the polishing pad may be peeled off from the surface plate, and the light source and the light detection device provided on the surface plate side may be adversely affected. In this regard, in the techniques of Patent Document 6 and Patent Document 7, since one of the polishing layer and the light transmitting portion is brought into contact before solidifying in a liquid state, the degree of adhesion becomes high and liquid leakage is unlikely to occur. However, since the surface of the light transmitting portion is not formed with an opening and does not have the ability to hold the slurry, not only does the polishing performance deteriorate or become non-uniform, but also the object to be polished transmits light after the polishing process is completed. There is a problem in that a dechucking error that makes it difficult to remove the object to be polished due to being in close contact with the portion tends to occur. In addition, when the light transmitting portion is disposed on the entire polishing surface, it is difficult to obtain sufficient polishing performance.

  In order to form a transparent light-transmitting part having a polishing ability, a technique is disclosed in which polymer capsules (resin fine particles) having a liquid core are contained in a light-transmitting polymer matrix (resin material) (for example, patents) Reference 8). Moreover, the technique of mix | blending water-soluble microparticles | fine-particles with a light transmissive part is disclosed (for example, refer patent document 9).

JP-A-7-52032 Japanese Patent No. 3508747 Japanese Patent No. 3431115 Japanese Patent No. 3327817 Japanese Patent No. 3913969 Japanese Patent No. 3691852 Japanese Patent No. 4019087 JP 2007-83387 A JP 2002-324769 A

  However, in the techniques of Patent Document 8 and Patent Document 9, since the polymer capsule and water-soluble fine particles are contained in the light transmitting portion, an opening is formed in the polishing surface due to abrasion of the polishing pad (polishing layer). At the same time, the hardness of the light transmission part itself is reduced. For this reason, a part with different hardness is formed in the polishing surface, which leads to a decrease in polishing performance and a decrease in flatness of the object to be polished. In order to make the light transmission part as hard as the polishing layer even if the opening is formed, it is necessary to form the light transmission part harder than the polishing layer in a state before the opening is formed. However, even in this case, there is a risk of poor polishing due to the difference in hardness. In addition, when a general technique for forming foam in the polishing layer is used to impart polishing ability to the light transmitting portion, light is scattered and it becomes difficult to obtain sufficient light transmission. Furthermore, in foam formation by adding water or enclosing an inert gas, it is difficult to control the size, and a huge foam having a diameter of several hundreds μm may be formed, resulting in poor polishing. In addition, the inclusion of hollow fine particles makes it easy to control the size, but the hollow fine particles may not be opened and may be exposed to the polished surface without decreasing hardness, resulting in poor polishing such as polishing scratches (scratches). It is easy to cause.

  An object of the present invention is to provide a polishing pad capable of optically detecting the polishing state and improving the polishing performance in view of the above-mentioned cases.

  In order to solve the above-described problems, the present invention provides a polishing layer made of a resin having a polishing surface for polishing an object to be polished, and at least a part of the polishing layer, and a polishing liquid covering the entire thickness. An infiltration permissible portion allowing infiltration, and hollow resin fine particles having a hemispherical or semi-polyhedral outer shell dispersed substantially uniformly inside the polishing layer including the infiltration allowable portion, and the polishing The layer is formed by foaming inside by the gas previously arranged in the hollow part of the resin fine particles or the contained component, and is formed integrally with the infiltration allowable part, It is a polishing pad characterized by exhibiting light transmittance when the polishing liquid infiltrates from the polishing surface.

  In the present invention, foaming is formed by a gas or a component contained in the hollow part of the resin fine particles in which the polishing layer is substantially uniformly dispersed therein, and the foaming of the entire polishing layer is formed integrally with the infiltration allowing part. Since the structure is uniformed and the leakage of the polishing liquid is suppressed, the polishing performance can be improved, and the permeation allowing portion constituting at least a part of the polishing layer can be removed from the polishing surface over the entire thickness. Since the light penetration is suppressed and the light transmission is exhibited by the infiltration, the polishing state can be optically detected in the light reflection state on the processing surface of the object to be polished during the polishing process.

  In this case, it is preferable that the polishing layer is formed of a polyurethane resin, and the polyurethane resin forming the infiltration allowable portion has hydrophilicity. At this time, the polyurethane resin forming the infiltration allowable portion may have a crosslinking density smaller than that of the polyurethane resin forming the polishing layer other than the infiltration allowable portion. Further, at least the resin fine particles dispersed in the infiltration-permitted portion are those in which the outer shell is formed of a hydrophilic resin or the surface of the outer shell is subjected to a hydrophilic treatment, and preferably has light transmittance. At this time, the outer shell is made of a silicone resin, and the surface thereof can be hydrophilized with a surfactant. In the permeation allowing portion, when the polishing liquid is infiltrated, it is possible to show a transmittance of 30% or more with respect to a light beam having a wavelength in the range of 190 nm to 3500 nm. It is preferable that an aperture having an average aperture diameter of 10 μm to 150 μm is formed on the polishing surface of the polishing layer. Further, the contained component can be a chemical foaming agent or water that is solid at room temperature and generates gas at 100 ° C. to 260 ° C. Further, the resin fine particles may be dispersed in a weight ratio of 5 parts to 50 parts with respect to 100 parts of the polishing layer including the infiltration allowable part. Groove processing or embossing can be performed on the polishing surface side of the polishing layer. A cushion material may be further bonded to the surface of the polishing layer opposite to the polishing surface. At this time, it is preferable that an opening is formed in the cushion material at a position corresponding to the infiltration allowing portion.

  According to the present invention, the entire polishing layer is formed by forming the foam by the gas or the contained component in the hollow portion of the resin fine particles in which the polishing layer is substantially uniformly dispersed therein, and being formed integrally with the infiltration permitting portion. The foamed structure of the polishing layer is made uniform and leakage of the polishing liquid is suppressed, so that the polishing performance can be improved and the permeation allowing portion constituting at least a part of the polishing layer is polished from the polishing surface over the entire thickness. The effect of being able to optically detect the polishing state in the light reflection state on the processing surface of the object to be polished during polishing processing because light scattering is suppressed by infiltration of the liquid and light transmittance is exhibited. 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 20 has a urethane sheet 2 as a polishing layer. The urethane sheet 2 has an isocyanate group-containing compound as a main component, and has a polishing surface P for polishing a surface to be polished (processed surface) of an object to be polished during polishing.

  At least a part of the urethane sheet 2 is formed with a hydrophilic resin portion 3 as an infiltration allowing portion that allows infiltration of a liquid component of a polishing liquid (a slurry containing abrasive grains) supplied during polishing. In the hydrophilic resin portion 3, infiltration of the liquid component of the polishing liquid is allowed over the entire thickness of the urethane sheet 2. As shown in FIG. 3A, the polishing pad 20 is formed in a circular shape. The hydrophilic resin portion 3 is formed in a circular shape at one location between the central portion and the peripheral portion of the urethane sheet 2 (polishing pad 20).

  The urethane sheet 2 is formed by slicing a polyurethane molded body obtained by reaction curing of a mixed liquid containing an isocyanate group-containing compound and an active hydrogen compound. The hydrophilic resin portion 3 is formed on at least a part of the urethane sheet 2 by reacting and curing a mixed solution containing an isocyanate group-containing compound having hydrophilicity and an active hydrogen compound. That is, the urethane sheet 2 is formed of a polyurethane resin, and in the hydrophilic resin portion 3, the polyurethane resin is formed of a hydrophilic polyurethane resin having hydrophilicity. The urethane sheet 2 is formed integrally with the hydrophilic resin portion 3. The hydrophilic polyurethane resin forming the hydrophilic resin portion 3 has a crosslink density smaller than that of the polyurethane resin forming the portion other than the hydrophilic resin portion 3 of the urethane sheet 2. Inside the urethane sheet 2 including the hydrophilic resin portion 3, hollow fine particles (resin fine particles) 13 having a hemispherical resin outer shell are contained (internally added) in a substantially uniform and substantially uniformly dispersed state. ing. In such a hydrophilic resin portion 3, the polishing liquid infiltrates from the polishing surface P during polishing and exhibits light transmittance. In other words, the hydrophilic resin portion 3 infiltrated with the polishing liquid exhibits a transmittance of 30% or more with respect to a light beam having any wavelength in the range of 190 to 3500 nm.

  As shown in FIG. 2, the fine particles 13 have a hemispherical outer shell 13a, and a hollow recess 13b is formed at the center. In other words, the fine particles 13 have a bowl-like shape in which hollow spherical fine particles are roughly divided into two to form openings. The fine particles 13 are light transmissive, and the surface of the outer shell 13a is hydrophilized. In this example, the outer shell 13a of the fine particles 13 is formed of a silicone resin, and the surface thereof is hydrophilized with a surfactant. In the opening portion of the fine particles 13, the average outer diameter (particle diameter) is adjusted to be in the range of about 10 to 150 μm. The fine particles 13 are previously provided with a foam-forming component 14 that forms foam when the polyurethane molded body is formed in the depression 13b.

  As the foam-forming component 14, a gas or a foaming component (containing component) can be used. As the gas, a gas that is non-reactive with the material used for forming the polyurethane molded body is used. Examples of such a gas include air and carbon dioxide. When a gas is used for the foam forming component 14, the gas is mixed in a state where it is disposed in the depression 13b when the polyurethane molded body is formed. The gas expands due to heat generated by the curing reaction of the polyurethane resin, and foam is formed. Moreover, as a foaming component, the chemical foaming agent or water which is solid at normal temperature and thermally decomposes at 100-260 degreeC and generate | occur | produces a decomposition gas can be used. In the case of water, a gas is generated by reacting with an isocyanate group at the time of forming a polyurethane molded body, and foaming is formed. The foaming component is preferably held in the depression 13b at a weight ratio of 5 to 50 parts with respect to 100 parts of the fine particles 13. If the amount of the foaming component is too small, the foam formation is insufficient. On the other hand, if the amount is too large, the size of the foam formed tends to vary. In other words, the foaming component is adjusted to an amount required to form foam having substantially the same size as the particle diameter of the fine particles 13.

  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 foamed dispersion at the early stage when forming a polyurethane molded product. Even if a body is formed, it does not decompose and foam is not formed, which is not preferable.

  As shown in FIG. 1, in the urethane sheet 2 including the hydrophilic resin portion 3, the foam 5 is substantially equalized by the foam-forming component 14 of the gas or the foam component previously contained in the depression 13 b of the fine particles 13. And it is formed substantially uniformly. For this reason, the urethane sheet 2 and the hydrophilic resin portion 3 have a foamed structure. Since the foam 5 is formed by the foam forming component 14, the fine particles 13 are included in the foam 5. The content of the fine particles 13 is set to a weight ratio of 5 to 50 parts with respect to 100 parts of the urethane sheet 2 including the hydrophilic resin part 3. If the content of the fine particles 13 is too small, the number of foams 5 to be formed is reduced, and the slurry retention is insufficient. On the other hand, if the content of the fine particles 13 is too large, the density of the urethane sheet 2 is decreased by the amount of the foam 5 and the polishing performance may be deteriorated. FIG. 1 shows a state in which the fine particles 13 are encapsulated in one foam 5 formed in the urethane sheet 2 and the hydrophilic resin portion 3, and the fine particles 13 are omitted in the remaining foam 5.

  Further, since the urethane sheet 2 is formed by subjecting the polyurethane molded body to surface grinding treatment such as slicing treatment, an opening 6 in which the foam 5 is opened on the polishing surface P is formed. The opening 6 is formed with an average opening diameter in the range of 10 to 150 μm because the foam 5 formed by the foam-forming component 14 is formed to have approximately the same size as the particle diameter of the fine particles 13. The thickness of the urethane sheet 2 is set in the range of 1.3 to 2.5 mm.

  A cushion sheet 16 is bonded to the surface of the urethane sheet 2 opposite to the polishing surface P. The urethane sheet 2 and the cushion sheet 16 are bonded together with only an adhesive or a double-sided tape in which an adhesive layer is formed on both surfaces of a base material. Both the adhesive and double-sided tape used for this bonding have light transmittance. The cushion sheet 16 has a function of imparting cushioning properties to the polishing pad 20. As the cushion sheet 16, an elastic sheet material can be used. In this example, a polyurethane resin sheet material is used. An opening 17 is formed in the cushion sheet 16 at a position corresponding to the hydrophilic resin portion 3. The opening 17 is formed with an opening area that is narrower than the area of the polishing surface P of the hydrophilic resin portion 3 so that the hydrophilic resin portion 3 can be supported. A double-sided tape 18 for attaching the polishing pad 20 to the polishing machine is bonded to the surface of the cushion sheet 16 opposite to the urethane sheet 2. The double-sided tape 18 has an adhesive layer formed on both sides of a substrate such as a film made of polyethylene terephthalate (hereinafter abbreviated as PET). The base material and the adhesive layer constituting the double-sided tape 18 have light transmittance as a whole. Examples of the adhesive for the adhesive layer include acrylic adhesives. The double-sided tape 18 is bonded to the cushion sheet 16 with an adhesive layer on one side, and the adhesive layer on the other side is covered with a release paper (not shown). Further, a groove 8 having a rectangular cross section is formed on the polishing surface P side of the polishing pad 20 in order to promote the movement of slurry and the discharge of polishing debris during polishing. The grooves 8 are formed in a lattice shape when viewed from the polishing surface P side.

(Manufacture of polishing pad)
The polishing pad 20 is manufactured through each process shown in FIG. That is, a preparation step of preparing an isocyanate group-containing compound, a hydrophilic isocyanate group-containing compound, an active hydrogen compound, and fine particles 13, respectively, a first mixture in which the isocyanate group-containing compound, the active hydrogen compound, and the fine particles 13 are mixed. A mixing step of preparing a liquid and a second mixed liquid in which an isocyanate group-containing compound having hydrophilicity, an active hydrogen compound and fine particles 13 are mixed; the first mixed liquid is cast into a mold and the curing reaction proceeds; A curing molding step for injecting and curing the second mixed liquid to form a polyurethane molded body before the curing reaction is completed, and a sheet for forming the urethane sheet 2 including the hydrophilic resin portion 3 by slicing the polyurethane molded body. Forming step, groove forming step of forming the groove 8 on the polishing surface P side of the urethane sheet 2, and cushioning the urethane sheet 2. DOO 16 is manufactured by the lamination step of laminating the double-sided tape 18. Hereinafter, it demonstrates in order of a process.

(Preparation process)
In the preparation step, an isocyanate group-containing compound, a hydrophilic isocyanate group-containing compound, an active hydrogen compound, and fine particles 13 are prepared. As the 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). In addition, the foam forming component 14 may foam due to the temperature rise, and the size and dispersion state of the foam 5 may vary. On the other hand, if the viscosity is too low, the fine particles 13 move in the mixed solution, and it becomes difficult to disperse the fine particles 13 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 adjusted 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.

  Although it does not restrict | limit especially as a diisocyanate compound used for the production | generation of a prepolymer, For example, 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'-dimethyl Diphenylmethane-4,4′-diisocyanate, xylylene-1,4-diisocyanate, 4,4′-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene Examples include 1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p-phenylene diisothiocyanate, xylylene-1,4-diisothiocyanate, and ethylidine diisothiocyanate. Can do. 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.

  As the isocyanate group-containing compound having hydrophilicity, an isocyanate-terminated hydrophilic urethane formed 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 Prepolymers (hereinafter simply referred to as hydrophilized prepolymers) are used. If the polyol compound has, in the main chain, a hydrophilic portion that is easily compatible with water, such as an ether bond, a hydrophilized prepolymer can be produced. By making the molar amount of the isocyanate group of the diisocyanate compound larger than the molar amount of the hydroxyl group of the polyol compound, a hydrophilized prepolymer can be obtained. It is preferable that the hydrophilized prepolymer sets the viscosity at a temperature of 50 to 80 ° C. in the range of 500 to 4000 mPa · s, like the prepolymer described above.

  As the polyol compound used for the production of the hydrophilized prepolymer, among the polyol compounds used for the production of the prepolymer described above, a polyether polyol compound, a reaction product of ethylene glycol and adipic acid, and the like can be used. On the other hand, as a diisocyanate compound used for the production | generation of a hydrophilized prepolymer, the diisocyanate compound used for a normal prepolymer production | generation can be mentioned. That is, the hydrophilicity of the hydrophilized prepolymer can be imparted by a hydrophilic polyol compound.

  As the active hydrogen compound to be prepared, it is sufficient if it has an active hydrogen group that reacts with the terminal isocyanate group of the prepolymer or the hydrophilized prepolymer, and a polyamine compound or a polyol compound can be used. The active hydrogen compound reacts with the isocyanate group of the prepolymer or the hydrophilized 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. A polyfunctional active hydrogen compound such as a triamine compound or a triol compound reacts with a prepolymer or a hydrophilized prepolymer to form a three-dimensional network resin, but it is hydrophilic by adjusting the blending ratio of the polyfunctional active hydrogen compound. The polyurethane resin can be formed with a crosslinking density smaller than that of the polyurethane resin.

  Further, the fine particles 13 in which the foam forming component 14 is arranged in the depression 13b can be formed as follows, for example. In this example, the outer shell 13a is formed of an organic silicone 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 13 made of an organic silicone resin and having a hemispherical outer shell 13a. As a catalyst for the condensation reaction, a catalyst used for hydrolysis can be used. The produced fine particles 13 are dehydrated and dried by heating using a centrifugal separation method, a pressure filtration method, or the like. By performing a separation process, variation in size can be reduced and the range of particle diameters can be adjusted.

  In the obtained fine particles 13, the surface of the outer shell 13a is hydrophilized by a surfactant. In the hydrophilization treatment, the fine particles 13 are immersed in a surfactant solution, stirred under reduced pressure, and then dried. When the bubbles escape from the depression 13b under reduced pressure, the surface of the outer shell 13a, which is inherently hydrophobic, comes into contact with the surfactant and is hydrophilized. Surfactants used include cationic surfactants such as aliphatic amine salts and aliphatic ammonium salts, fatty acid soaps, carboxylates, alkylbenzene sulfonates, alkyl naphthalene sulfonates, sulfonates, and higher alcohol sulfates. Examples include anionic surfactants such as salts, alkyl ether sulfates, sulfate esters, and phosphate ester salts, and nonionic surfactants such as ether types, ether ester types, and ester types. More than one species can be used in combination.

  The foam-forming component 14 is held in the depression 13b of the fine particles 13 subjected to the hydrophilic treatment. When water or a chemical foaming agent is used as the foam-forming component 14, the fine particles 13 are immersed in a solution of the foam-forming component 14, stirred and mixed under reduced pressure, and then dried. By stirring under reduced pressure, the bubbles escape from the recess 13b, and the foam-forming component 14 enters the recess 13b. When a gas is used as the foam-forming component 14, the hydrophilized fine particles 13 are exposed as they are to the atmosphere of the gas used. At this time, if moisture is contained in the gas to be used, unexpected foaming may be formed by reacting with the isocyanate group of the prepolymer or hydrophilized prepolymer in the curing molding process. Is desirable. In this state, the gas is held in the depression 13b, and is mixed in a state in which the gas is arranged at the time of preparing a mixed liquid described later. Further, by adjusting the particle size range of the fine particles 13, the size of the recess 13 b is formed so as to be substantially the same, so that the foam-forming component 14 is in a small amount in the recess 13 b with little variation in quantity. Retained. In this example, air is used as the foam forming component 14.

(Mixing process, curing molding process)
As shown in FIG. 4, in the mixing step, the first mixed liquid prepared by mixing the prepolymer prepared in the preparing step, the active hydrogen compound and the fine particles 13, and the second mixed liquid prepared by mixing the hydrophilized prepolymer, the active hydrogen compound and the fine particles 13. And prepare. At this time, the fine particles 13 are mixed and dispersed in the active hydrogen compound substantially uniformly in advance in order to make the dispersion state in the first and second mixed liquids uniform. In the curing molding step, the prepolymer of the first mixed solution and the hydrophilized prepolymer of the second mixed solution are crosslinked and cured in two stages to mold a polyurethane molded body including a hydrophilic resin portion. In this example, the mixing process and the curing molding process are performed continuously.

  In the mixing step, first and second mixers are used to prepare the first and second mixed liquids, respectively. Each of the mixers includes a mixing tank in which a stirring blade is incorporated. In the first mixer, two supply tanks containing the prepolymer and the active hydrogen compound in which the fine particles 13 are dispersed are arranged on the upstream side of the mixing tank, and in the second mixer, hydrophilicity is provided on the upstream side of the mixing tank. Two supply tanks each containing a prepolymer and an active hydrogen compound in which fine particles 13 are dispersed are arranged. The supply port from each supply tank is connected to the upstream end of each mixing tank. The stirring blade is fixed to a rotating shaft arranged from the upstream side to the downstream side at a substantially central portion in the mixing tank. As the rotating shaft rotates, the stirring blade rotates, and the components are mixed so as to shear. Since many of the prepolymer, the hydrophilized prepolymer, and the active hydrogen compound are all solid or difficult to flow at normal temperature, each supply tank is heated so that each component can flow.

  The prepolymer or the hydrophilized prepolymer and the active hydrogen compound in which the fine particles 13 are dispersed are supplied from the respective supply tanks to the mixing tank, and are mixed by the rotation of the stirring blade. By adjusting the mixing conditions in each mixer, that is, the speed and rotation speed of the stirring blade, the respective components are mixed substantially uniformly and substantially uniformly to prepare the first and second mixed liquids, respectively. If the speed of the stirring blade is too low, the dispersed state of the fine particles 13 becomes non-uniform. On the other hand, if the speed is too high, the temperature rises due to heat generated by friction between the stirring blade and the mixed solution, and the viscosity of the mixed solution decreases. For this reason, the fine particles 13 easily move during molding, and the dispersion state of the fine particles 13 in the molded body varies. On the other hand, if the rotational speed is too small, it is difficult to make the dispersed state of the fine particles 13 uniform. On the other hand, if the rotational speed is too large, the viscosity decreases due to the temperature rise, and the dispersed state of the fine particles 13 varies.

  The prepared first and second mixed liquids are respectively discharged from a discharge port formed at the downstream end of the mixing tank and continuously cast. As the mold, a rectangular container having an open upper part and a cylindrical block fixed in a removable state between the container center and the outer wall is used. In this example, the size of the mold is set to 1050 mm (length) × 1050 mm (width) × 50 mm (thickness), and the size of the cylindrical block is 200 mm (diameter) × 50 mm (height). Is set to

  In the curing and molding step, the first mixed solution is cast into a mold to advance the crosslinking and curing. When casting the first mixed liquid into the mold, the first mixed liquid is discharged from the discharge port of the first mixer, and is poured into the mold approximately evenly through, for example, a flexible pipe. Crosslinking and curing proceeds by the reaction of the prepolymer with the active hydrogen compound. Since the upper part of the mold is open, the reaction (crosslinking curing) proceeds under atmospheric pressure. Before the cross-linking and curing of the first mixed liquid is completed, the second mixed liquid is injected into the opening formed by removing the columnar block in the mold, and the cross-linking and curing proceeds. At this time, the second liquid mixture is discharged from the discharge port of the second mixer, and injected into the above-described opening through, for example, a flexible pipe. By completing the cross-linking and curing of the first and second mixed liquids, a polyurethane molded body including a hydrophilic resin portion is molded. Since the second mixed liquid is injected and the cross-linking hardening proceeds before the cross-linking and hardening of the first mixed liquid is completed, a cross-linking bond is also formed at the boundary portion between the first and second mixed liquids. Moreover, the volume of the air of the foam forming component 14 arranged in the depression 13b of the fine particles 13 expands due to the reaction heat generated during the cross-linking and curing. Since the fine particles 13 are dispersed substantially uniformly and substantially uniformly in the first and second mixed liquids, the foaming 5 is formed in the polyurethane molded body including the hydrophilic resin portion by the progress of cross-linking curing around the fine particles 13. Are formed substantially uniformly and substantially uniformly.

(Sheet formation process)
As shown in FIG. 4, 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, and urethane containing the hydrophilic resin portion 3. Sheet 2 is formed. 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 in the mold 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 due to scratches and the like, and about 30 mm in the central portion. From 10 to 25 urethane sheets 2 can be formed. In order to improve the thickness accuracy of the urethane sheet 2, a surface grinding process such as a buff process may be further performed. A general buffing machine can be used for buffing. Since the foam 5 is formed substantially uniformly and substantially uniformly in the urethane molded body including the hydrophilic resin portion in the curing molding process, when a plurality of urethane sheets 2 are formed in the sheet forming process, the openings formed on the surface are formed. The average aperture diameter of the holes 6 is in the range of 10 to 150 μm.

(Lamination process)
In the laminating process, the urethane sheet 2 and the cushion sheet 16 formed in the sheet forming process are bonded together, and the double-sided tape 18 is bonded to the surface of the cushion sheet 16 opposite to the urethane sheet 2. For the bonding of the urethane sheet 2 and the cushion sheet 16, only an adhesive may be used, or a double-sided tape in which an adhesive is applied to both sides of a base material may be used. It is desirable to have properties. Further, when the urethane sheet 2 and the cushion sheet 16 are bonded together, the opening 17 of the cushion sheet 16 is positioned at a position where the hydrophilic resin portion 3 of the urethane sheet 2 is formed. Then, after cutting into a circular shape, the polishing pad 20 is completed by performing an inspection such as confirming that there is no dirt or foreign matter attached.

  When polishing an object to be polished, the polishing pad 20 is mounted on the polishing surface plate of the polishing machine. When the polishing pad 20 is mounted on the polishing surface plate, the release paper of the double-sided tape 18 is removed, and the surface is adhered and fixed to the polishing surface plate with the exposed adhesive layer. The object to be polished, which is held on the holding platen arranged so as to face the polishing platen, is pressed against the polishing surface P, and the polishing platen or holding platen is rotated while supplying the slurry from outside. The processed surface of the polished object 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. Further, the liquid component in the slurry infiltrates into the hydrophilic resin portion 3 so that the hydrophilic resin portion 3 is provided with light transmittance. At this time, in the hydrophilic resin portion 3, the transmittance indicating the ratio of the transmitted light energy to the incident light energy as a percentage with respect to a light beam having a wavelength in the range of 190 to 3500 nm is 30% or more. The polishing state of the object to be polished is detected via the hydrophilic resin portion 3 during the polishing process by the light source and the light detection device provided on the polishing machine side. Then, the polishing process is terminated when the polishing end point is detected optically.

(Action etc.)
Next, the operation and the like of the polishing pad 20 of this embodiment will be described.

  In the present embodiment, the hydrophilic resin portion 3 is formed on at least a part of the urethane sheet 2. Since the hydrophilic polyurethane resin forming the hydrophilic resin portion 3 has a smaller crosslink density than the polyurethane resin forming the portion other than the hydrophilic resin portion 3 of the urethane sheet 2, the hydrophilic resin portion 3 has a polishing liquid (slurry). Liquid components are likely to infiltrate. Since the liquid component of the slurry infiltrates into the hydrophilic resin portion 3, the hydrophilic resin portion 3 exhibits light transmittance. For this reason, during the polishing process, for example, the light source and the light detection device provided in the polishing machine (polishing surface plate) are changed from the light reflection state on the processing surface of the object to be polished through the hydrophilic resin portion 3 to the polishing state. Further, the polishing end point can be detected optically. As a result, polishing can be performed to the polishing end point without interruption, and the efficiency of the polishing process can be improved.

  In the present embodiment, since the fine particles 13 contained in the hydrophilic resin portion 3 are made of silicone resin, they have a light transmitting property, but the surface of the particles that are not inherently hydrophilic is hydrophilic with a surfactant. Has been. Foam 5 is formed in the hydrophilic resin portion 3 by the air disposed in the depressions 13 b of the fine particles 13. The liquid component of the slurry infiltrated into the hydrophilic resin portion 3 penetrates into the inside of the foam 5 and also penetrates into the hollow 13b subjected to the hydrophilic treatment, so that light scattering at the surface of the fine particles 13 and the hollow 13b is suppressed, and the hydrophilic component is hydrophilic. The light transmittance can be improved as a whole of the resin part 3. Since the hydrophilic resin portion 3 has a transmittance of 30% or more with respect to a light beam having a wavelength in the range of 190 to 3500 nm, the incident light is twice the thickness of the hydrophilic resin portion 3 (processing of the object to be polished). Even if the intensity is reduced by transmitting the reciprocating portion reflected by the surface, it is possible to obtain transmitted light having a sufficient intensity for detecting the polishing end point. In such a polishing pad 20, since the polishing end point can be detected in-situ, for example, it can be suitably used as a polishing pad when polishing a semiconductor device or the like by the CMP method.

  Furthermore, in this embodiment, the cushion sheet 16 is bonded to the surface opposite to the polishing surface P of the urethane sheet 2. For this reason, since the cushioning property is imparted to the polishing pad 20, irregularities and the like of the polishing surface plate can be absorbed. Thereby, the polishing process can be made uniform and the flatness of the object to be polished can be improved. A double-sided tape 18 is bonded to the surface of the cushion sheet 16 opposite to the urethane sheet 2. For this reason, mounting on the polishing surface plate can be facilitated. Furthermore, an opening 17 is formed in the cushion sheet 16, and the double-sided tape 18 as a whole has light transmittance. For this reason, inhibition of the light transmittance of the hydrophilic resin portion 3 can be avoided.

  Furthermore, in the present embodiment, the foam 5 is formed by the air (foam forming component 14) in which the urethane sheet 2 including the hydrophilic resin portion 3 is disposed in the recess 13 b having a substantially uniform size of the fine particles 13. For this reason, the foamed structure of the entire urethane sheet 2 including the hydrophilic resin portion 3 is made uniform without forming huge foam. Thereby, since the opening 6 is formed substantially uniformly and substantially uniformly on the polishing surface P, it is possible to improve the polishing performance by equalizing the supply of the slurry while ensuring the slurry retention.

  Furthermore, when the conventional hollow fine particles are contained, the resin outer shell does not open on the polishing surface, and there is a risk of causing a polishing flaw by contacting the object to be polished without reducing the hardness. On the other hand, in the present embodiment, since the fine particles 13 are hemispherical and open from the beginning, the outer shell is not exposed to the polished surface without decreasing its hardness and can be a foreign matter for polishing. Ingredients can be minimized. Thereby, the flatness can be improved without causing polishing scratches on the object to be polished.

  Further, in the present embodiment, before the crosslinking and curing of the polyurethane resin that forms the urethane sheet 2 is completed, the hydrophilic polyurethane resin (second mixed solution) that forms the hydrophilic resin portion 3 is injected to proceed the crosslinking and curing. In other words, before the polyurethane resin is completely solidified, the hydrophilic polyurethane resin comes into contact in a liquid state. For this reason, a cross-linking reaction proceeds between the polyurethane resin and the hydrophilic polyurethane resin, the degree of adhesion between the two can be improved, and the urethane sheet 2 and the hydrophilic resin portion 3 can be integrally formed. In addition, as described above, although the crosslink density of the hydrophilic polyurethane resin is smaller than that of the polyurethane resin, liquid permeability such that the liquid component of the slurry leaks out is not recognized due to the three-dimensional network structure at the molecular level. Therefore, even if the hydrophilic resin portion 3 is formed, it is possible to prevent the liquid component of the slurry from leaking out, and to avoid adverse effects on the polishing machine side.

  Furthermore, in this embodiment, the groove 8 is formed on the polishing surface P side of the urethane sheet 2 including the hydrophilic resin portion 3. For this reason, since the slurry supplied at the time of a grinding | polishing process moves, it is supplied to the whole grinding | polishing surface substantially equally, and discharge | emission of grinding | polishing waste is accelerated | stimulated, Therefore Polishing performance and grinding | polishing efficiency can be improved.

  Although not particularly mentioned in the present embodiment, the hydrophilic resin portion 3 is subjected to a grinding process or the like on the side opposite to the polishing surface P of the hydrophilic resin portion 3 in order to improve the light transmittance in the hydrophilic resin portion 3. You may make it make the thickness of 3 small. This is because when light is transmitted through the hydrophilic resin portion 3, the intensity of the light attenuates in proportion to the square of the thickness of the hydrophilic resin portion 3. Therefore, the light transmittance can be improved by reducing the thickness of the hydrophilic resin portion 3.

  In the present embodiment, an example in which the circular hydrophilic resin portion 3 is formed at one location between the center portion and the peripheral portion of the polishing pad 20 is shown, but the present invention is not limited to this. . Examples of the shape other than the circular shape include a rectangular shape and a fan shape. For example, as shown in FIG. 3B, a rectangular hydrophilic resin portion 23 having a long side in the radial direction of the polishing pad 20 may be formed. Moreover, you may form in two or more places also about the number of the hydrophilic resin parts 3. FIG. Furthermore, in this embodiment, although not specifically mentioned, a hydrophilicity imparting agent and a light stabilizer may be blended in the hydrophilic resin portion 3 as necessary. By doing so, it is possible to improve and stabilize the light transmittance of the hydrophilic resin portion 3.

  Furthermore, in this embodiment, the hydrophilic resin part 3 exhibits light transmittance, and shows a transmittance of 30% or more for a light beam having a wavelength in the range of 190 to 3500 nm. For example, it is possible to use light rays in the visible region. The light in the visible region usually has a wavelength in the range of 380 to 780 nm, and the hydrophilic resin portion 3 exhibits a transmittance of 30% or more for the light in this range. Although not specifically illustrated in the present embodiment, for example, a light emitting diode (LED) can be cited as a light source (light emitting element) on the polishing machine side, and a phototransistor or the like can be used as the detection device (light receiving element). Can be mentioned. Further, in the urethane sheet 2 other than the hydrophilic resin portion 3, the infiltration property of the slurry is very small as compared with the hydrophilic resin portion 3, and the light scattering is larger than that of the hydrophilic resin portion 3 considering that the foam 5 is formed. Light transmittance is reduced.

  Furthermore, in this embodiment, although the example which forms the microparticles | fine-particles 13 made from an organosilicone resin by carrying out the condensation reaction of the silanol compound was shown, this invention is not restrict | limited to this. Any method can be used as long as it can form the hemispherical fine particles 13. The material is not limited to the organic silicone resin, and may be light transmissive. Moreover, since the organic silicone resin is inherently hydrophobic, an example of hydrophilic treatment with a surfactant has been shown. However, if the material itself is a hydrophilic resin, the hydrophilic treatment may not be performed. Furthermore, in the present embodiment, an example in which the fine particles 13 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 hollow hexahedral or hollow octahedral particles can also be used. Of course, the shape of the recess 13b is not limited in any shape.

  Furthermore, in the present embodiment, an example in which the fine particles 13 are mixed with an active hydrogen compound in advance to prepare each liquid mixture has been shown, but the present invention is not limited to this, and is mixed with a prepolymer or a hydrophilized prepolymer. You can also keep it. When water is used as the foam-forming component 14 disposed in the depression 13b, it is preferable to mix it with an active hydrogen compound in order to avoid reaction with isocyanate groups. The fine particles 13 may be mixed as a single 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.

  Moreover, although the example which performs mixed liquid preparation, casting, and hardening molding continuously was shown in this embodiment, this invention is not restrict | limited to this and may be made to perform each independently. Moreover, although the example which shape | molds under atmospheric pressure using the open type | mold container as a formwork was shown in this embodiment, this invention is not restrict | limited to this. For example, the liquid mixture may be prepared in a container that also serves as a mold and cured and molded in the container, or the container may be sealed and cured and molded under pressure.

  Furthermore, in this embodiment, although the example which forms the polyurethane molded object which contains a hydrophilic resin part using the formwork which arranged the cylindrical block in the open mold container was shown, this invention is not restrict | limited to this. . For example, the urethane sheet 2 may be formed by casting a mixed liquid obtained by mixing the hydrophilized prepolymer, the active hydrogen compound and the fine particles 13 into a mold having no cylindrical block. In this way, a polishing pad having the entire urethane sheet 2 as the hydrophilic resin portion 3 can be obtained. In the present embodiment, the urethane sheet 2 is formed of a polyurethane resin and the hydrophilic resin portion 3 is formed of a hydrophilic polyurethane resin. However, the present invention is not limited to the resin, and various resins are used. Can be used. Further, the resin forming the hydrophilic resin portion and the resin forming the polishing layer other than the hydrophilic resin portion may be the same or different from each other. It is preferable that the resin is.

  Furthermore, in the present embodiment, an example in which the grooves 8 having a rectangular cross section are formed in a lattice shape on the polishing surface P side of the polishing pad 20 is shown, but the present invention is not limited to this. The shape of the groove may be a radial shape, a spiral shape, or the like, and the cross-sectional shape may be a U shape, a V shape, a semicircular shape, or the like other than a rectangular 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. There is a possibility of causing scratches on the polished object. In this embodiment, since the opening 6 of the polishing pad 20 is substantially uniform in the range of the average opening diameter of 10 to 150 μm, the occurrence of polishing flaws can be suppressed even if the groove processing is performed. Furthermore, embossing may be performed instead of grooving, and the same effect as grooving can be obtained.

  Furthermore, in the present embodiment, an example in which the cushion sheet 16 is interposed between the urethane sheet 2 and the double-sided tape 18 is shown, but a polishing pad can be formed without bonding the cushion sheet 16 together. It is preferable to interpose a cushion sheet in consideration of absorbing unevenness of the polishing surface plate and polishing pad, thickness unevenness due to mounting, etc., and making the polishing of the object to be polished more uniform.

  Hereinafter, examples of the polishing pad 20 manufactured according to the present embodiment will be described. A comparative polishing pad manufactured for comparison is also shown.

Example 1
In Example 1, PTMG having an average molecular weight of about 2000 as a polyol compound and 2,4-TDI as a diisocyanate compound were reacted to obtain a prepolymer having a viscosity at a temperature of 50 ° C. of 5500 mPa · s and an NCO equivalent of 549. . Further, a polyethylene glycol having an average molecular weight of about 2000 as a polyol compound and TDI as a diisocyanate compound were reacted to obtain a hydrophilized prepolymer having a viscosity of 5500 mPa · s at a temperature of 50 ° C. and an NCO equivalent of 549. MOCA was used as the active hydrogen compound. As the fine particles 13, an outer shell 13 a having an average particle diameter of 10 μm was formed of an organosilicone polymer, and air was disposed as the foam forming component 14 in the depression 13 b. Prepolymer or hydrophilized prepolymer: MOCA: fine particles 13 were mixed at a weight ratio of 100 parts: 22.8 parts: 5.3 parts to prepare first and second mixed liquids, respectively. The stirring conditions at the time of mixing were set to 1689 rotations and a speed of 9425 / second. After curing and molding, the polishing pad 20 was prepared by slicing to a thickness of 1.3 mm.

(Comparative Example 1)
In Comparative Example 1, the hollow spherical fine particles (Matsumoto Yushi Seiyaku Co., Ltd., Matsumoto Microbead M-610, cross-linked acrylic type) were used, and the hydrophilic resin part 3 was not formed. A polishing pad was produced. 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 of each Example and the comparative example, the average hole diameter of the hole 6 and the light transmittance of the hydrophilic resin part 3 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 light transmittance was evaluated by measuring the transmittance of light having a wavelength of 500 nm after each polishing pad was immersed in water. The average pore diameter and light transmittance measurement results are shown in Table 1 below.

  As shown in Table 1, in the polishing pad of Comparative Example 1 in which the hollow spherical fine particles were dispersed, the average pore diameter on the polishing surface P was 9.8 μm. On the other hand, in the polishing pad 20 of Example 1 in which the hydrophilic resin portion 3 was formed and the hemispherical fine particles 13 were dispersed, the average pore diameter was 9.5 μm. From this, it was found that the urethane sheet of Comparative Example 1 and the urethane sheet 2 of Example 1 were formed with foam having the same size as the hollow spherical fine particles and fine particles 13 respectively. In Comparative Example 1, the light transmittance of the urethane sheet was 10%, whereas in Example 1, the light transmittance was 52%. From this, it was found that the polishing end point can be optically detected during the polishing process in the polishing pad 20 of Example 1.

(Polishing performance evaluation)
Next, using the polishing pads of the examples and comparative examples, 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 of the aluminum substrate, and the specific gravity. In addition, the presence or absence of scratches on the aluminum substrate by polishing was visually determined. The measurement results of the polishing rate and the presence or absence of scratches 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 0.182 μm / min, and scratches were confirmed. On the other hand, in the polishing pad 20 of Example 1, the polishing rate was improved to 0.195 μm / min, and no scratch was observed. Further, in the polishing pad of Comparative Example 1, it was necessary to interrupt the polishing process and inspect the processed surface in order to determine the polishing end point, whereas in the polishing pad 20 of Example 1, the polishing end point was detected optically. As a result, polishing could be performed without interruption. Therefore, the urethane sheet 2 formed with the hydrophilic resin portion 3 is used, and the foam 5 is formed on the urethane sheet 2 including the hydrophilic resin portion 3 with the foam-forming component 14 disposed in the depression 13b of the fine particles 13, thereby optically polishing. It was found that the end point can be detected and a sufficient polishing rate can be obtained.

  Since the present invention provides a polishing pad capable of optically detecting the polishing state and improving the polishing performance, and contributes to the manufacture and sale of the polishing pad, it has industrial applicability.

It is sectional drawing which shows typically 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 a top view which shows typically the hydrophilic resin part formed in the urethane sheet which comprises a polishing pad. It is process drawing which shows the principal part of the manufacturing method of the polishing pad of embodiment.

Explanation of symbols

P Polished surface 2 Urethane sheet (polishing layer)
3 Hydrophilic resin part (infiltration allowed part)
5 Foam 13 Fine particles (resin fine particles)
13a outer shell 13b hollow 20 polishing pad

Claims (12)

A resin polishing layer having a polishing surface for polishing an object to be polished;
An infiltration permissible portion that constitutes at least part of the polishing layer and allows infiltration of the polishing liquid over the entire thickness; and
Hollow resin fine particles having a hemispherical or semi-polyhedral outer shell dispersed substantially uniformly inside the polishing layer including the infiltration allowing portion,
With
The polishing layer is formed by foaming inside by a gas previously arranged in a hollow portion of the resin fine particles or a contained component, and is formed integrally with the infiltration allowable portion, and the infiltration allowable The polishing pad is characterized in that the polishing liquid infiltrates from the polishing surface to exhibit light transmittance.   The polishing pad according to claim 1, wherein the polishing layer is made of a polyurethane resin, and the polyurethane resin forming the infiltration allowing portion has hydrophilicity.   3. The polishing pad according to claim 2, wherein the polyurethane resin forming the infiltration-permitted portion has a smaller cross-linking density than the polyurethane resin forming the polishing layer other than the infiltration-permitting portion.   At least the resin fine particles dispersed in the infiltration-permitted portion are characterized in that the outer shell is formed of a hydrophilic resin or the surface of the outer shell is subjected to a hydrophilic treatment, and has light transmittance. The polishing pad according to claim 1.   The polishing pad according to claim 4, wherein the outer shell is formed of a silicone resin, and the surface is subjected to a hydrophilic treatment with a surfactant.   2. The polishing according to claim 1, wherein the infiltration allowing portion exhibits a transmittance of 30% or more with respect to a light beam having a wavelength in a wavelength range of 190 nm to 3500 nm when the polishing liquid infiltrates. pad.   2. The polishing pad according to claim 1, wherein the polishing layer has an opening having an average opening diameter of 10 μm to 150 μm formed on the polishing surface.   The polishing pad according to claim 1, wherein the contained component is a chemical foaming agent or water that is solid at normal temperature and generates gas at 100 to 260 ° C.   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 polishing layer.   The polishing pad according to claim 1, wherein the polishing layer is grooved or embossed on the polishing surface side.   The polishing pad according to claim 1, wherein a cushion material is further bonded to a surface opposite to the polishing surface of the polishing layer.   The polishing pad according to claim 11, wherein the cushion material has an opening formed at a position corresponding to the infiltration allowing portion.

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