JP5130138B2 - Polishing pad and manufacturing method thereof - Google Patents

Description

  The present invention relates to a polishing pad and a method for producing the same, and in particular, a resin polishing layer having a polishing surface for polishing an object to be polished, and hollow resin fine particles dispersed substantially uniformly in the polishing layer. And a manufacturing method of the polishing pad in which a light transmission part is formed in a polishing layer.

  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 where a processed surface of an object to be polished is pressed against a polishing pad. The polishing pad used usually has 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 general, in the polishing process, the polishing is terminated when the object to be polished reaches a desired surface characteristic or flat state, and therefore it is necessary to detect the polishing end point. Conventionally, in order to determine the polishing end point, the object to be polished is taken out from the polishing apparatus and the surface characteristics and the like are evaluated at another place. When the object to be polished did not reach the desired surface characteristics, the object to be polished was remounted on the polishing apparatus, and repolishing was performed. For this reason, the polishing process becomes complicated, and the object to be polished may be excessively polished. In order to solve this problem, various techniques have been disclosed for detecting the polishing end point in-situ during polishing. As a method for optically detecting a polishing end point, for example, a technique of observing reflected light from a processed surface with an imaging device is disclosed (see Patent Document 1 and Patent Document 2). Based on these techniques, a technique for detecting a polishing end point by irradiating an object to be polished with a light beam such as a laser through a light transmitting portion formed on a polishing pad is disclosed (see Patent Documents 3 to 8). ).

  The polishing pads of Patent Literature 3 to Patent Literature 5 have a structure in which an opening is formed in the polishing layer, and a light-transmissive window member made of a member different from the polishing layer is fitted in the opening of the polishing layer. have. This polishing pad has a problem in that slurry leakage is likely to occur between the polishing layer and the light transmission portion (window portion) except when the light transmission portion is formed on the entire surface of the polishing layer. In this respect, the polishing pads of Patent Document 6 and Patent Document 7 have a structure in which the members constituting the polishing layer or the members constituting the light transmission portion are brought into contact with each other and solidified before solidifying. The bonding property between the polishing layer and the light transmission part is high, and it is difficult for the slurry to leak. However, since the light transmission part is formed of a hard member different from the polishing layer, it is difficult to polish uniformly, and there is a risk of causing poor polishing such as scratches (polishing scratches) on the object to be polished. In the polishing pad of Patent Document 8, a part of the polishing layer is heated and pressurized after the resin of the polishing layer having a foam structure is cured, thereby reducing the foam and forming the light transmission part. In this polishing pad, since the polishing layer and the light transmission part are integrally formed of the same member, it is possible to prevent slurry from leaking and suppress poor polishing.

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 2007-245308 A

  However, in the technique of Patent Document 8, the resin material is mixed and reaction-cured, and then reheated and then pressed to form the light transmission part. Therefore, the light transmission part and its surrounding resin may be deteriorated. There is. In addition, although foam is formed inside the polishing layer by water or the like, the foam structure may become non-uniform due to the difference in the dispersion state of water or the like. By mixing hollow spherical resin fine particles in the polishing layer, the foam structure can be made uniform. However, when the hollow spherical fine particles do not open on the polished surface, the hardness of the hollow spherical fine particles is not reduced, and the outer shell The component may cause an unexpected polishing failure as a foreign substance and may reduce the flatness of the object to be polished.

  An object of the present invention is to provide a polishing pad capable of optically detecting a polishing end point and improving polishing performance and a method for manufacturing the same.

  In order to solve the above-mentioned problem, a first aspect of the present invention is a resin-made polishing layer having a polishing surface for polishing an object to be polished, and a hemisphere substantially uniformly dispersed in the polishing layer. And fine resin particles having a hollow or semi-polyhedral outer shell, and foaming is formed in the polishing layer by a gas previously arranged in a hollow portion of the resin fine particles or a pre-containing component And at least a part of the polishing layer is pressurized in the thickness direction before the polishing layer is cured, thereby forming a light transmission portion that compresses the foam and allows light transmission, and A polishing pad, wherein a polishing surface of the polishing layer and one side surface of the light transmission portion are continuously formed.

  In the first aspect, since a part of the polishing layer is pressed in the thickness direction before the polishing layer is cured, the foam is compressed and the light transmission part is formed. It does not require heating, and it can suppress the deterioration of the light transmission of the light transmission part and the deterioration of the light transmission part and the resin adjacent to the light transmission part, and the resin fine particles are dispersed almost uniformly inside the polishing layer. Since the foam is formed by the gas or contained component previously arranged in the hollow part of the resin fine particles, the foam structure is made uniform, so that the supply of the slurry is equalized while ensuring the retention of the slurry Thus, the polishing performance can be improved, and the polishing surface of the polishing layer and one side surface of the light transmission portion are continuous, so that the polishing performance can be maintained.

  In the first aspect, it is preferable that the light transmission portion exhibits a transmittance of 30% or more with respect to a light beam having a wavelength in the range of 190 to 3500 nm. The difference in Shore D hardness between the light transmission part and the polishing layer is preferably 10 degrees or less. The thickness of the light transmission part may be 80% or less of the thickness of the polishing layer excluding the light transmission part. A step may be formed between the other side surface of the light transmission portion and the surface opposite to the polishing surface of the polishing layer. The other side surface of the light transmitting portion may be recessed toward the polishing surface side of the polishing layer with respect to the surface opposite to the polishing surface of the polishing layer. The polishing layer can be formed of a polyurethane resin. It is preferable that at least the outer shell of the resin fine particles dispersed in the light transmitting portion has light transmittance, and can be formed of a silicone resin. A cushion material may be further bonded to the surface of the polishing layer opposite to the polished surface, and at this time, it is preferable that an opening is formed in the cushion material at a position corresponding to the light transmitting portion.

  According to a second aspect of the present invention, there is provided a polishing pad manufacturing method according to the first aspect, wherein a mixed liquid is prepared in which an isocyanate group-containing compound, an active hydrogen compound, and the resin fine particles are substantially uniformly mixed. The mixing step and the crosslinking curing reaction with the isocyanate group-containing compound and the active hydrogen compound are allowed to proceed, and at least a part of the reaction product is pressurized in the thickness direction before the crosslinking curing reaction is completed, so that the light transmitting portion is A forming step of forming a polyurethane molded body.

  According to the present invention, since a part of the polishing layer is pressed in the thickness direction before the polishing layer is cured, the foam is compressed and the light transmission part is formed. It does not require heating, and it can suppress the deterioration of the light transmission of the light transmission part and the deterioration of the light transmission part and the resin adjacent to the light transmission part, and the resin fine particles are dispersed almost uniformly inside the polishing layer. Since the foam is formed by the gas or contained component previously arranged in the hollow part of the resin fine particles, the foam structure is made uniform, so that the supply of the slurry is equalized while ensuring the retention of the slurry Thus, the polishing performance can be improved, and the polishing surface of the polishing layer and the one side surface of the light transmitting portion are continuous. Therefore, the effect of maintaining the polishing performance 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 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 light transmission portion 3 that allows light transmission. As shown in FIG. 3 (A), the polishing pad 1 is formed in a circular shape, and the light transmission part 3 is formed in a circle between a central part and a peripheral part of the urethane sheet 2 (polishing pad 1). It is formed into a shape.

  As shown in FIG. 1, the urethane sheet 2 including the light transmission part 3 is formed by pressing the urethane sheet 2 in the thickness direction before the curing reaction of the polyurethane resin constituting the urethane sheet 2 is finished (before curing). Has been. That is, both the urethane sheet 2 and the light transmission part 3 are integrally formed of polyurethane resin. Moreover, the polishing surface P of the urethane sheet 2 and the upper surface (one side surface) of the light transmission part 3 are continuously formed. Inside the urethane sheet 2 including the light transmission part 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.

  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 formed of a silicone resin whose outer shell 13a has light transmittance. In this example, the fine particles 13 are adjusted so that the average outer diameter (particle diameter) of the opening portion is in the range of about 10 to 150 μm. The fine particles 13 are provided with a pore-forming component 14 that forms pores (foam) 5 in the depressions 13b. In this example, the pore forming component 14 is 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 pore forming component 14 is too small, the formation of the pores 5 will be insufficient, and conversely if too large, the size of the pores 5 to be formed tends to vary. In other words, the pore-forming component 14 is adjusted to an amount required to form the pores 5 having a size substantially the same as the particle size of the fine particles 13.

  As the pore 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 resin is used. Examples of such a gas include air and carbon dioxide. The foaming component may be a chemical foaming agent or water that is solid at room temperature and thermally decomposes at 100 ° C. to 260 ° C. to generate a decomposition gas. In the case of water, gas reacts with the isocyanate group-containing compound that is the main component of the urethane sheet 2 to generate gas and form pores 5.

  As the chemical foaming agent, for example, selected from barium azodicarboxylate, N, N′-dinitrosopentamethylenetetramine, sodium hydrogen carbonate, azodicarbonamide, 4,4′-oxybisbenzenesulfonylhydrazide and hydrazodicarbonamide 1 type, or 2 or more types can be used. If the thermal decomposition temperature of the chemical foaming agent is less than 100 ° C., it is difficult to equalize and homogenize the dispersed state of the pores 5 because the decomposition starts early due to heat of reaction during the curing reaction of the polyurethane resin. If it exceeds ℃, even if the curing reaction of the polyurethane resin is completed, it does not decompose and pores 5 are not formed.

  As shown in FIG. 1, the pores 5 are formed substantially uniformly and substantially uniformly inside the urethane sheet 2 excluding the light transmitting portion 3 by the pore-forming component 14 disposed in the depressions 13 b of the fine particles 13. On the other hand, in the light transmission part 3, pores (not shown) formed by the pore forming component 14 are compressed by pressurization. For this reason, the urethane sheet 2 excluding the light transmission part 3 has a substantially uniform foamed structure. Since the pores 5 are formed by the pore-forming component 14 arranged in the depression 13 b, the fine particles 13 are included in the pores 5. In this example, 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. If the content of the fine particles 13 is too small, the number of pores 5 to be formed is reduced, and the retention of the slurry becomes insufficient. On the contrary, if the content of the fine particles 13 is too large, the density of the urethane sheet 2 is reduced by the increase in the number of pores 5 and the polishing performance may be deteriorated. FIG. 1 shows a state in which the fine particles 13 are encapsulated in one pore 5 formed in the urethane sheet 2, and the encapsulated fine particles 13 are omitted in the remaining pores 5. In addition, one fine particle 13 dispersed in the light transmitting portion 3 is shown, and the remaining fine particles 13 are shown in an isolated manner.

  The light transmission part 3 is formed by pressing (pressing) in the thickness direction from the side opposite to the polishing surface P of the urethane sheet 2 before the polyurethane resin is cured. Hereinafter, the surface (other side surface) opposite to the polishing surface P of the light transmission portion 3 is referred to as the opposite surface of the light transmission portion 3, and the surface opposite to the polishing surface P of the urethane sheet 2 is referred to as the opposite surface of the urethane sheet 2. . The opposite surface of the light transmitting portion 3 is recessed toward the polishing surface P with respect to the opposite surface of the urethane sheet 2. In other words, a step is formed between the opposite surface of the light transmission part 3 and the opposite surface of the urethane sheet 2. In this example, the thickness of the light transmission part 3 is set in the range of 0.5 to 2.0 mm, and the thickness of the urethane sheet 2 excluding the light transmission part 3 is in the range of 1.3 to 2.5 mm. Is set to That is, the thickness of the light transmission part is set to 80% or less of the thickness of the urethane sheet 2 excluding the light transmission part. If the pressing pressure is too small, the pores are not compressed and light is scattered by the pores, so that sufficient light transmission cannot be obtained. On the contrary, if the pressure to be pressed is too large, the hardness of the light transmission part 3 is increased, and the hardness difference between the light transmission part 3 and the urethane sheet 2 excluding the light transmission part 3 is increased, which may cause polishing failure. There is. In this example, the difference in Shore D hardness between the light transmission part 3 and the urethane sheet 2 excluding the light transmission part 3 is adjusted to be 10 degrees or less. Moreover, in this example, the light transmission part 3 is formed so as to exhibit a transmittance of 30% or more with respect to a light beam having any wavelength within a wavelength range of 190 to 3500 nm.

  Since the urethane sheet 2 is formed by subjecting polyurethane resin to a surface grinding process such as a slicing process, an opening 6 in which pores 5 are formed in the polishing surface P is formed. Since the pores 5 formed by the pore-forming component 14 are formed to have almost the same size as the particle size of the fine particles 13, the apertures 6 are formed with an average aperture diameter of 10 to 150 μm.

  A cushion sheet (cushion material) 16 is bonded to the opposite surface of the urethane sheet 2. 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 1. 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 light transmission part 3. A double-sided tape 18 for attaching the polishing pad 1 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). In addition, a groove 8 having a rectangular cross section is formed on the polishing surface P side of the polishing pad 1 in order to promote the movement of the slurry and the removal 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 1 is manufactured through each process shown in FIG. That is, a preparation step of preparing an isocyanate group-containing compound, an active hydrogen compound, and fine particles 13 respectively, a mixing step of preparing a mixed solution in which the isocyanate group-containing compound, the active hydrogen compound, and the fine particles 13 are substantially uniformly mixed, an isocyanate group The cross-linking curing reaction with the contained compound and the active hydrogen compound is allowed to proceed, and the reaction product is sliced into a sheet before completion of the cross-linking curing reaction, and at least a part of the sheet-like reaction product in the thickness direction. A molding step for forming a urethane sheet 2 (polyurethane molded body) including the light transmitting portion 3 by pressing (pressing), a groove processing step for forming a groove 8 on the polishing surface P side of the urethane sheet 2, and cushioning the urethane sheet 2 The sheet 16 and the double-sided tape 18 are manufactured through a laminating process. 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 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), and on the contrary, mixed spots are generated and the dispersion state of the fine particles 13 is varied. Further, the pore forming component 14 may foam due to the temperature rise, and the size and dispersion state of the pores 5 may vary. On the contrary, 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 resin. 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. 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 13 in which the pore forming component 14 is arranged in the depression 13b can be formed as follows, for example. In this example, by using a silanol group-forming silicon compound or a silanol group-forming compound that generates a silanol compound by hydrolysis, the outer shell 13a is formed of an organic silicone resin having light transmittance. 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. The obtained fine particles 13 are immersed in a solution of the pore-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 pore-forming component 14 enters the recess 13b. By adjusting the particle size range of the fine particles 13, the depressions 13 b are formed to have substantially the same size. Therefore, the pore-forming component 14 is held in the depressions 13 b in a small amount and with little variation in quantity. The In this example, air is used as the pore forming component 14.

(Mixing process)
As shown in FIG. 5, in the mixing step, the prepolymer prepared in the preparation step, the active hydrogen compound, and the fine particles 13 are mixed by a mixer 20 to prepare a mixed solution. 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 mixed solution uniform. The mixer 20 includes a mixing tank 22 in which a stirring blade 24 is built. On the upstream side of the mixing tank 22, a supply tank containing a prepolymer as a first component and an active hydrogen compound in which fine particles 13 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 22. The agitating blade 24 is fixed to a rotating shaft arranged from the upstream side to the downstream side at a substantially central portion in the mixing tank 22. As the rotating shaft rotates, the stirring blade 24 rotates and mixes the first component and the second component so as to shear. 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 22 and mixed by the stirring blade 24. By adjusting the mixing conditions in the mixer 20, that is, the shearing speed and the number of shearing of the stirring blade 24, the components are mixed substantially uniformly and substantially uniformly to prepare a mixed solution. If the shear rate of the stirring blade 24 is too low, the dispersed state of the fine particles 13 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 24 and the mixed solution, and the viscosity of the mixed solution decreases. For this reason, the fine particles 13 are easily moved when the resin is cured, and the dispersion state of the fine particles 13 in the resin varies. In addition, the pore forming component 14 may foam due to the temperature rise, and the size and dispersion state of the pores 5 may become non-uniform. On the other hand, if the number of shears is too small, it is difficult to make the dispersed state of the fine particles 13 uniform. On the other hand, if the number of shears is too large, the viscosity decreases due to a temperature rise and the dispersed state of the fine particles 13 varies. For this reason, in a mixing process, a shear rate is set to the range of 9,000-41,000 / sec, and the frequency | count of shear is set to the range of 300-10,000 times, and it mixes. The mixing time (residence time) in the mixer 20 is about 1 second although it depends on the flow rate of the mixed liquid (maximum 1 liter / sec). 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 24 × circumferential rate × rotational speed (rpm) of stirring blade 24 ÷ 60 ÷ blade tip of stirring blade 24 and inner wall of mixing vessel 22 Clearance (mm), number of shears (times) = rotation speed of stirring blade 24 (rpm) ÷ 60 × retention time of mixed solution in mixing tank 22 (second) × number of blades of stirring blade 24 Can do.

(Molding process)
In the molding process, a casting step in which the mixed solution is cast into a mold, a curing step in which a crosslinking curing reaction of the mixed solution proceeds in the mold, and a sheet obtained by slicing the reaction product before the completion of the crosslinking curing reaction The polyurethane molded body including the light transmitting portion 3 is formed through a slicing step and a pressing step for forming the light transmitting portion 3 by pressing at least a part of the sheet-like reaction product in the thickness direction. . Hereinafter, the molding process will be described in the order of steps.

(Casting step)
In the casting step, the liquid mixture obtained in the mixing process is discharged from a discharge port formed at the downstream end of the mixing tank 22, and the liquid injection (not shown) disposed above the mold 25 through a flexible pipe, for example. Liquid is introduced into the mouth. 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). 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. 5), 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. 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.

(Curing step)
In the curing step, a block-shaped reaction product (hereinafter, referred to as solidified to the extent that the cross-linking curing reaction with the prepolymer and the active hydrogen compound in the cast liquid mixture proceeds in the mold 25 and can be sliced). A urethane block). That is, the urethane block has not completely completed the cross-linking curing reaction and can be deformed by pressurization. Since the upper part of the mold 25 is opened, the crosslinking and curing reaction proceeds under atmospheric pressure to form a urethane block. Further, the pore-forming component 14 disposed in the depression 13b of the fine particles 13 generates gas by the reaction heat generated by this reaction. Since the fine particles 13 are dispersed substantially uniformly and substantially uniformly in the mixed solution, the pores 5 are formed substantially uniformly and substantially uniformly in the urethane block as the crosslinking curing reaction proceeds around the fine particles 13.

(Slice step)
In the slicing step, the urethane block obtained in the curing step is sliced before the end of the crosslinking and curing reaction to form a sheet-like reaction product (hereinafter referred to as a urethane sheet). A general slicing machine can be used for slicing. At the time of slicing, the lower layer portion of the urethane block 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 to a range of 1.3 to 2.5 mm. In the urethane block formed 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 urethane block is not used due to scratches and the like, and from about 30 mm of the central portion. 10 to 25 urethane sheets can be formed. Since the urethane block in which the pores 5 are formed substantially uniformly and substantially uniformly in the curing step is obtained, when a plurality of urethane sheets are formed in the slicing step, the average opening diameter of the openings 6 formed on the surface is Is also in the range of 10 to 150 μm.

(Pressure step)
A part of the urethane sheet obtained in the slicing step is pressed in the thickness direction before the end of the crosslinking and curing reaction (before curing) to form the light transmission part 3. At the time of pressing, a urethane sheet is placed on a flat plate, and pressure is applied in a circular shape on the lower side so that a desired light transmittance can be obtained on a part of the urethane sheet. At this time, since the crosslinking curing reaction has not been completed, the pores formed by the pore forming component 14 are compressed inside the light transmitting portion 3, and sufficient light transmission for detecting the polishing end point is ensured. The urethane sheet 2 including the light transmitting portion 3 is formed by completing the crosslinking and curing reaction of the urethane sheet in the pressed state. In this example, the pressure is set so that the thickness of the light transmission part 3 is in the range of 0.5 to 2.0 mm.

(Grooving process)
As shown in FIG. 4, in the groove processing step, a lattice-shaped groove 8 having a rectangular cross section is formed on the polishing surface P side of the urethane sheet 2 in consideration of supply of slurry at the time of polishing and discharge of polishing debris. Further, in order to improve the thickness accuracy of the urethane sheet 2, a surface grinding process such as buffing may be further performed on the opposite surface of the urethane sheet 2. A general buffing machine can be used for buffing.

(Lamination process)
In the laminating step, the urethane sheet 2 and the cushion sheet 16 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 surfaces of a base material may be used. It is desirable to have In addition, 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 light transmitting portion 3 of the urethane sheet 2 is formed. Then, after cutting into a circular shape, an inspection such as confirming that there is no adhesion of dirt or foreign matter is performed, and the polishing pad 1 is completed.

  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 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. At this time, the position of the light transmission part 3 formed on the polishing pad 1 is matched with the position of the light irradiation part provided on the polishing surface plate. By pressing the object to be polished held on the holding surface plate arranged to face the polishing surface plate to the polishing surface P side and rotating the polishing surface plate or holding surface plate while supplying slurry from the outside. The processed surface of the object to be polished is polished. The processed surface of the object to be polished is polished while the supplied slurry is held in the opening 6 formed in the polishing surface P. During the polishing process, the processed surface of the object to be polished is irradiated from the polishing surface plate side through the light transmitting portion 3 of the polishing pad 1 and a polishing process is performed while observing the polishing state. When the processed surface of the object to be polished reaches a desired surface characteristic or flat state, it is detected as a polishing end point, and the polishing process is completed. Normally, water is used as a medium for the polishing liquid, but an organic solvent such as alcohol can also be mixed.

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

  In this embodiment, at least a part of the urethane sheet 2 has a light transmission part 3, and the light transmission part 3 is thick before the polyurethane resin constituting the urethane sheet 2 finishes the crosslinking curing reaction (before curing). It is formed by pressing in the direction. For this reason, since the pores are compressed inside the light transmitting portion 3, light scattering by the pores is suppressed. Further, since the outer shell 13a of the fine particles 13 contained in the light transmitting portion 3 is made of a silicone resin having light transmittance, it is difficult to inhibit light transmission. Therefore, in the light transmission part 3, the transmittance | permeability of 30% or more is shown with respect to the light ray of any wavelength within the range of 190 to 3500 nm, and incident light is twice as much as the thickness of the light transmission part 3 (of the object to be polished). Even if the intensity is reduced by transmitting the reciprocating portion reflected by the processed surface, it is possible to obtain transmitted light having a sufficient intensity for detecting the polishing end point. In such a polishing pad 1, since the polishing end point can be detected in-situ, it is possible to improve the efficiency of the polishing process. For example, as a polishing pad for polishing a semiconductor device or the like by the CMP method It can be preferably used.

  Moreover, in this embodiment, the thickness of the light transmission part 3 is 80% or less of the thickness of the urethane sheet 2 excluding the light transmission part 3, and the opposite surface of the light transmission part 3 and the opposite surface of the urethane sheet 2 A step is formed between them. In other words, the opposite surface of the light transmission part 3 is recessed toward the polishing surface P with respect to the opposite surface of the urethane sheet 2. For this reason, since the thickness of the light transmission part 3 becomes thin, even if incident light permeate | transmits 2 times the thickness of the light transmission part 3, it becomes difficult to reduce the intensity | strength of light, and the detection performance of a polishing end point is improved. Can be improved.

  Further, when a light transmission part is formed by reheating and pressurizing after curing of the conventional polyurethane resin, there is a possibility that the light transmission part and the surrounding resin are deteriorated or light transmittance is deteriorated such as discoloration. . In addition, there is a risk that the abrasion scraps of the resin deteriorated during the polishing process may fall off and cause contamination. On the other hand, in this embodiment, the light transmission part 3 is formed by pressurizing before the bridge | crosslinking hardening reaction of the polyurethane resin which comprises the urethane sheet 2 is complete | finished (before hardening). For this reason, reheating is not required, deterioration of the resin and light transmission can be suppressed, and contamination due to a deteriorated resin during polishing can be suppressed. Moreover, since reheating is not required, the manufacturing process can be made more efficient.

  Furthermore, in this embodiment, the cushion sheet 16 is bonded to the opposite surface of the urethane sheet 2. For this reason, since the cushioning property is imparted to the polishing pad 1, the unevenness 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. Further, 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, obstruction of the light transmittance of the light transmission part 3 can be avoided.

  Furthermore, in the present embodiment, the fine particles 13 are contained in the urethane sheet 2 substantially uniformly and substantially uniformly in a weight ratio of 5 to 50 parts with respect to 100 parts. In addition, pores 5 are formed in the urethane sheet 2 excluding the light transmission portion 3 by the pore-forming component 14 disposed in the depressions 13 b of the fine particles 13. For this reason, the formation of huge pores is suppressed, and the pores 5 having a substantially uniform particle diameter are formed substantially uniformly inside the urethane sheet 2 excluding the light transmission part 3. Therefore, since the foamed structure of the urethane sheet 2 excluding the light transmitting portion 3 is made uniform, the openings 6 are formed substantially uniformly and substantially uniformly on the polishing surface P, so that the slurry can be retained while securing the slurry. Can be made uniform to improve the polishing performance.

  Further, 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 scratches (polishing scratches) on the object to be polished.

  Furthermore, in this embodiment, the polishing surface P of the urethane sheet 2 and the upper surface (one side surface) of the light transmission part 3 are continuously formed. For this reason, as compared with the case where a separate member is fitted in the opening of the urethane sheet to form a light transmission part, it is possible to prevent slurry leakage and the like, and to avoid adverse effects on the polishing machine. Moreover, when the urethane sheet 2 and the light transmission part 3 are formed of different members, there is a possibility that the polishing performance may be lowered due to the difference in the material between the two. On the other hand, in this embodiment, both the urethane sheet 2 and the light transmission part 3 are formed of polyurethane resin, and the Shore D hardness of the urethane sheet 2 excluding the light transmission part 3 and the light transmission part 3 Is set to 10 degrees or less, the polishing performance can be maintained.

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

  In the present embodiment, the example in which the circular light transmitting portion 3 is formed at one location between the center portion and the peripheral portion of the polishing pad 1 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 light transmission portion 23 having a long side in the radial direction of the polishing pad 1 may be formed. Moreover, you may form in two or more places also about the number of the light transmissive parts 3. FIG.

  Moreover, in this embodiment, the light transmission part 3 has a light transmittance, and shows the transmittance | permeability of 30% or more about the light ray of any wavelength within the range of 190-3500 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 light transmission part 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 present embodiment, an example is shown in which the urethane block 2 including the light transmitting portion 3 is formed by slicing and pressing the urethane block before the polyurethane resin is completely cured, but the present invention is limited to this. It is not a thing. You may form the urethane sheet 2 which has the light transmissive part 3 by slicing, after pressing from the lower surface side of a urethane block before completion of hardening of a polyurethane resin, without slicing a urethane block. In this case, since the light transmission part is formed in the upper layer part of the urethane block, the thickness of the light transmission part 3 and the light transmission part 3 are excluded by slicing to a predetermined thickness in order from the upper layer part of the urethane block. The thickness of the urethane sheet 2 can be formed substantially the same. That is, no step is formed between the opposite surface of the light transmission part 3 and the opposite surface of the urethane sheet 2.

  Furthermore, in the present embodiment, an example is shown in which a urethane sheet is placed on a flat plate, and a part of the urethane sheet is pressed (pressurized) before the polyurethane resin is cured to form the light transmitting portion 3. However, the present invention is not limited to this. For example, a urethane sheet or urethane block is placed on a flat plate on which protrusions are formed, and the entire upper surface of the urethane sheet or polyurethane block is pressed (pressed) substantially uniformly and substantially uniformly before the polyurethane resin is cured. Alternatively, the light transmission part 3 may be formed.

  Furthermore, in this embodiment, although the example which obtains several sheets of urethane sheets by slicing a urethane block was shown, this invention is not limited to this. For example, without using the mold 25, the urethane sheet may be formed one by one by applying it in a sheet form on a substrate having a flat surface. In this case, the opening 6 can be formed by subjecting the surface side to surface grinding treatment such as slicing treatment or buffing treatment.

  Moreover, in this embodiment, although the polishing pad 1 using the sheet-like urethane sheet 2 as an abrasive layer was illustrated, this invention is not limited to this, According to the grinding | polishing processing method, block-like grinding | polishing is carried out. It can also be a pad. For example, after forming a light transmission part in the urethane block shown in this embodiment, it may be used for polishing as it is.

  Furthermore, in this embodiment, the example which distribute | arranges the pore formation component 14 to the hollow 13b of the microparticle 13 was shown, and air was illustrated as the pore formation component 14, However, This invention is not limited to these. For example, water can be disposed in the depression 13b. As an example, the fine particles 13 in which water is arranged in the depression 13b are obtained by immersing the fine particles 13 in water, stirring and mixing under reduced pressure, and then drying. By stirring under reduced pressure, air bubbles escape from the recess 13b, and water enters the recess 13b. Since water reacts with the isocyanate group of the prepolymer to generate gas, pores are formed in the same manner as when air is used. In addition, water itself may vaporize. Even in such a case, since the amount of water distributed in the depression 13b is limited, it is possible to avoid the formation of extremely large pores inside the polyurethane resin and to make the foam structure uniform. Further, the size of the fine particles 13 and the mixing ratio of the pore-forming component 14 are not particularly limited, and may be adjusted in consideration of the gas generation amount of the pore-forming component 14.

  Furthermore, in this embodiment, although the example which forms the fine particle 13 made from the organosilicone resin which has a light transmittance 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 is a method capable of forming the hemispherical fine particles 13, and the outer shell 13 a is not limited to the organic silicone resin as long as it is a light-transmitting resin. Needless to say. 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, the example in which the fine particles 13 are mixed with the active hydrogen compound in advance in the mixing step to form the second component is shown. However, the present invention is not limited to this, and is mixed with the prepolymer. It can also be set as the first component. In the mixing step, the fine particles 13 may be mixed alone as the third component, but in this case, it is preferable to disperse them in an organic solvent or the like in order to make the dispersion state uniform.

  Moreover, in 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 this embodiment, although the example which forms the groove | channel 8 with a rectangular cross section in the grid | lattice form was shown in the polishing surface P of the polishing pad 1, this invention is not limited to this. An embossing process may be applied instead of the groove process. The shape of the groove may be any of a radial shape, a spiral shape, and the like, and the cross-sectional shape may be any of 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 this embodiment, since the opening 6 of the polishing pad 1 is substantially uniform in the range of 10 to 150 μm in the average value of the hole diameter, it is possible to suppress the generation of scratches on the object to be polished even when the groove is processed.

  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, 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. MOCA was used as the active hydrogen compound, dissolved at about 120 ° C. and degassed under reduced pressure. As the fine particles 13, an outer shell 13 a having an average particle diameter of 10 μm was formed of an organic silicone polymer, and air was disposed as a pore forming component 14 in the depression 13 b. Prepolymer: MOCA: fine particles 13 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. After the resulting mixed liquid is cast into a mold 25 and solidified to such an extent that it can be sliced, the urethane block is extracted from the mold 25 before the curing reaction is finished, sliced to a thickness of 1.3 mm, and pressurized at 5 MPa. Thus, the light transmitting portion 3 was formed to prepare the polishing pad 1. The thickness of the light transmission part 3 was set to 1.0 mm, that is, 80% of the thickness of the urethane sheet 2 excluding the light transmission part 3. The difference in Shore D hardness between the light transmission part 3 and the urethane sheet 2 excluding the light transmission part 3 was set to 8 degrees.

(Comparative Example 1)
In Comparative Example 1, a polishing pad was used in the same manner as in Example 1 except that hollow spherical fine particles (Matsumoto Yushi Seiyaku Co., Ltd., Matsumoto Microbead M-610, cross-linked acrylic type) were used and the light transmission part 3 was not formed. Produced. The average particle size of the hollow spherical fine particles was set to 10 μm.

(Physical property measurement)
For the polishing pad 1 of Example 1, the average opening diameter of the openings 6 and the light transmittance of the light transmitting portion 3 were measured. For the polishing pad of Comparative Example 1, the average hole diameter and light transmittance of the holes formed on the polishing surface 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. 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 was 9.8 μm. In contrast, in the polishing pad 1 of Example 1 in which the hemispherical fine particles 13 were dispersed, the average pore diameter was 9.9 μm. From this, it was found that pores having the same size as the hollow spherical fine particles were formed in Comparative Example 1 and the size of fine particles 13 was formed in Example 1. In Comparative Example 1, the light transmittance was less than 30%. In contrast, in Example 1, the light transmittance was 30% or more. From this, it was found that the polishing end point can be optically detected during the polishing process in the polishing pad 1 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 0.181 μm / min, and scratches were also confirmed. On the other hand, in the polishing pad 1 of Example 1 in which the hemispherical fine particles 13 in which the pore forming component 14 is arranged in the depression 13b are dispersed, the polishing rate is improved to 0.196 μm / min, and scratches are recognized. There wasn't. 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 1 of Example 1, the polishing end point was detected optically. As a result, polishing could be performed without interruption. Therefore, by using the urethane sheet 2 including the light transmitting portion 3 and forming the pores 5 in the urethane sheet 2 excluding the light transmitting portion 3 by the pore forming component 14 disposed in the depressions 13 b of the fine particles 13, the optical polishing end point is obtained. It was found that a sufficient polishing rate can be obtained.

  Since the present invention provides a polishing pad capable of optically detecting the polishing end point and improving the polishing performance and a method for manufacturing the same, it contributes to the manufacture and sale of the polishing pad, so that it can be used industrially. Have sex.

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 the light transmissive 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. It is a block diagram which shows the outline of the mixer and mold which were used for manufacture of the polishing pad of embodiment.

Explanation of symbols

1 Polishing pad 2 Urethane sheet (polishing layer)
3 Light transmission part 5 Pore (foaming)
13 Fine particles (resin fine particles)
13a outer shell 13b hollow (hollow part)
14 Pore-forming components (gas or contained components)
P Polished surface

Claims (11)

A resin polishing layer having a polishing surface for polishing an object to be polished;
Hollow resin fine particles having a hemispherical or semi-polyhedral outer shell dispersed substantially uniformly inside the polishing layer;
With
In the polishing layer, foam is formed by a gas previously disposed in the hollow portion of the resin fine particles or a pre-containing component, and at least a part of the polishing layer has a thickness before the polishing layer is cured. The foam is compressed by pressurizing in the direction to form a light transmission part that allows light transmission, and the polishing surface of the polishing layer and one side surface of the light transmission part are continuously formed. A polishing pad characterized by that.   2. The polishing pad according to claim 1, wherein the light transmission portion exhibits a transmittance of 30% or more with respect to a light beam having any wavelength in a wavelength range of 190 nm to 3500 nm.   2. The polishing pad according to claim 1, wherein a difference in Shore D hardness between the light transmitting portion and the polishing layer excluding the light transmitting portion is 10 degrees or less.   2. The polishing pad according to claim 1, wherein the thickness of the light transmission part is 80% or less of the thickness of the polishing layer excluding the light transmission part.   The polishing pad according to claim 1, wherein a step is formed between the other side surface of the light transmission portion and a surface opposite to the polishing surface of the polishing layer.   2. The polishing pad according to claim 1, wherein the other side surface of the light transmitting portion is recessed toward the polishing surface side of the polishing layer with respect to a surface opposite to the polishing surface of the polishing layer.   The polishing pad according to claim 1, wherein the polishing layer is formed of a polyurethane resin.   2. The polishing pad according to claim 1, wherein at least the resin fine particles dispersed in the light transmission portion have a light transmission property in the outer shell.   The polishing pad according to claim 8, wherein the outer shell is made of a silicone resin.   The cushioning material is further bonded to the surface opposite to the polishing surface of the polishing layer, and the cushioning material has an opening formed at a position corresponding to the light transmission portion. The polishing pad as described. It is a manufacturing method of the polishing pad according to claim 1,
A mixing step of preparing a mixed solution in which the isocyanate group-containing compound, the active hydrogen compound, and the resin fine particles are mixed substantially uniformly;
A polyurethane molded article containing the light transmitting part by proceeding a crosslinking and curing reaction with the isocyanate group-containing compound and the active hydrogen compound and pressurizing at least a part of the reaction product in the thickness direction before the crosslinking and curing reaction is completed. Forming process to form,
The manufacturing method characterized by including.

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