JP5117147B2 - Polishing pad and method of manufacturing polishing pad - Google Patents

Description

  The present invention relates to a method for manufacturing a polishing pad and a polishing pad, and more particularly to a polishing pad mainly composed of an isocyanate group-containing compound and a method for manufacturing the polishing pad.

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

  As a method for flattening the surface of a semiconductor wafer or glass substrate, a chemical mechanical polishing (hereinafter abbreviated as CMP) method is generally used. In the CMP method, a surface (surface to be polished) to be polished is pressed against a polishing pad, and a slurry (polishing liquid) in which abrasive particles are dispersed in an alkaline solution is supplied to polish the surface to be polished. Polishing is performed by mechanical action by abrasive particles in the slurry and chemical action by an alkaline solution. As the flatness required for the surface to be polished increases, the polishing accuracy required for the CMP method, in other words, the performance required for the polishing pad also increases.

  In the CMP method, rigid foam polyurethane is widely used as a polishing pad. In the production of such a polishing pad, usually, a prepolymer containing an isocyanate group-containing compound and a curing agent containing an active hydrogen compound are cured by reaction to form a foam. The obtained foam is sliced into a sheet to form a polishing pad. Since foam is formed inside the foam, an opening that can hold the slurry during polishing is formed on the surface of the polishing pad formed by slicing.

  For the purpose of molding a foam for a polishing pad, many techniques have been disclosed in which a thermoplastic resin or a thermosetting resin is used as a base material and a chemical foaming agent or a microcapsule containing a chemical foaming agent is added and molded. . For example, in a technique using a thermoplastic resin as a base material, a technique using a polyolefin resin (see Patent Documents 1 and 2), a technique using a fluorine resin (see Patent Documents 3 and 4), an acrylic resin, and an ABS resin are used. A technique (see Patent Document 5) is disclosed. On the other hand, in the technology using a thermosetting urethane resin as a base material, a microcapsule encapsulating a chemical foaming agent in a shell wall made of a polymer material is mixed with the raw material of the base material, and the chemical foaming agent is generated by the curing reaction heat of urethane resin. A technique is disclosed in which foams are formed by expanding microcapsules by breaking gas generated by decomposition and damaging the shell wall (see Patent Document 6).

However, since polishing scraps are generated during the polishing process, the holes are clogged with the polishing scraps, and there is a problem that the polishing efficiency and the flatness of the object to be polished are lowered. For this reason, a technique of a polishing pad formed by mixing fine foam of 100 μm or less and large foam exceeding a foam diameter of 100 μm is disclosed for the purpose of suppressing clogging due to polishing dust while maintaining slurry holding performance. Has been. For example, when molding a polyurethane resin containing plastic hollow particles, by foaming using a chemical foaming agent or water as a foaming agent, the number of closed cells with an average pore diameter of 0.3 mm or more is 1 / cm ² or more, A technique of a polishing pad having 100 / cm ² or more of closed cells having an average pore diameter of 0.1 mm or less is disclosed (see Patent Document 7). Also, by chemical foaming, mechanical stirring foaming, hollow microbead dispersion, etc., the average diameter of small foams with a foam diameter of less than 400 μm is 20-100 μm and large foams with a foam diameter of 400-1000 μm are 10-100 / 100 cm ^2. The technique of the formed polishing pad (see Patent Document 8) is disclosed. The present applicant also discloses a polishing pad in which pores having a pore diameter of 10 to 100 μm due to heat-expandable fine particles and foaming having a pore diameter of 100 to 800 μm due to water foaming are mixed (see Patent Documents 9 and 10).

JP-A-9-132661 JP 2003-286359 A JP-A 63-283857 Japanese Patent Laid-Open No. 2001-205552 JP 2001-239455 A JP-A-11-114834 JP 2001-244223 A JP 2006-210657 A Japanese Patent No. 3316757 Japanese Patent No. 3316756

  However, as in Patent Document 1 to Patent Document 5, in the case of foaming by adding a chemical foaming agent, if the base material is a thermoplastic resin, there is little risk of causing side reactions, but the base material is a thermosetting polyurethane resin. There is a disadvantage that the wear resistance is inferior to that of the above. However, in the thermosetting polyurethane resin, depending on the type of chemical foaming agent, the polyurethane mixture before molding inhibits polymerization, lowers viscosity, or conversely increases in viscosity or gelation, leading to foaming spots (the foaming varies. Occurs). In this respect, in Patent Document 6, since the chemical foaming agent is protected by the shell wall made of the polymer material, the problems of polymerization inhibition and viscosity change are solved. However, the polymer material of the shell wall is not polished during polishing. Between the polishing pad and the polishing pad, as a contaminant, may cause an unexpected adverse effect due to the slurry used. In the techniques of Patent Documents 7 to 10, the same problem as that of Patent Document 6 is caused by the inclusion of hollow fine particle components as impurities. Further, in foaming by adding water, it is difficult to equalize the dispersion state of water, so that there is a problem that the foam of the molded foam is biased and the average pore diameter is likely to be different. In addition to the above, the foaming method includes physical foaming in which an inert gas is enclosed. If foaming has an average pore diameter of about several μm, it is easier to control than foaming with water, but the average pore diameter is several tens. There is a problem that it is difficult to form and equalize a slightly large foam in the μm range.

  An object of the present invention is to provide a polishing pad capable of stably supplying a polishing liquid and improving the flatness of an object to be polished, and a method for manufacturing the polishing pad, in view of the above-mentioned cases.

In order to solve the above-mentioned problems, the first aspect of the present invention comprises an isocyanate group-containing compound, a polyamine compound, and a thermal decomposition at 100 ° C. to 260 ° C. that is solid at room temperature and does not have an amide group or a hydrazide group. and a chemical foaming agent a for generating a decomposition gas Te, pyrolyzed decomposition gas generated at 100 ° C. to 260 ° C. has a solid at amide or hydrazide group at ordinary temperature, the chemical blowing pyrolyzing temperature is A foam formed from a mixed solution in which a chemical foaming agent B having a difference of 5 ° C. or more from the temperature at which the agent A is thermally decomposed is mixed so that the blending ratio is in the range of 50/50 to 20/80. A polishing pad obtained by slicing.

In the first aspect, the blending ratio of the chemical foaming agent A having no amide group or hydrazide group and the chemical foaming agent B having an amide group or hydrazide group is in the range of 50/50 to 20/80. , since the increase in viscosity of the mixture by a chemical foaming agent a, and decrease the viscosity of the mixture by chemical foaming agent B is less change in viscosity of the mixture is balanced, the dispersion state of the foam formed in the foam is equalized, because the pyrolysis temperature in a mixed chemical foaming agent a and a chemical foaming agent B in mixture has a difference of more than 5 ° C., the chemical foaming agent a, the thermal decomposition of the chemical blowing agent B separately It is easy to adjust the size and density of the foam by controlling it, and since the foam with a bipolar size is formed inside the foam, the surface of the polishing pad obtained by slicing is bipolar Openings with pore size distribution and almost even distribution Since the, the polishing liquid is stably supplied during polishing by the polishing pad, it is possible to improve the planarity of the polished object.

  In the first embodiment, the chemical blowing agent A is one or more selected from barium azodicarboxylate, N, N′-dinitrosopentamethylenetetramine and sodium hydrogen carbonate, and the chemical blowing agent B is azodicarbonamide. , 4,4′-oxybisbenzenesulfonylhydrazide and hydrazodicarbonamide may be used alone or in combination. If the chemical foaming agent A and the chemical foaming agent B are mixed in the liquid mixture as a dispersion obtained by dispersing and diluting the polyol compound in a proportion of 1% by weight to 20% by weight, respectively, the chemical foaming agent A in the liquid mixture , B can be equalized. At this time, the polyol compound may be polypropylene glycol.

Further, in the first aspect, if the viscosity of the isocyanate group-containing compound at a temperature of 50 ° C. to 80 ° C. is in the range of 500 mPa · s to 4000 mPa · s, the movement of foaming is suppressed in the mixed liquid, The bias can be suppressed. Openings are formed on the surface by slicing the foam, and the pore size distribution of the apertures is bipolarized within the range of 3 μm to 500 μm , and when each pore size distribution is assumed to be a normal distribution, one pore size distribution Is preferably outside the range of the center value ± standard deviation of the other pore size distribution, and the center value of the other pore size distribution is preferably outside the range of the center value ± standard deviation of the one pore size distribution . In addition, when a plurality of polishing pads are formed by slicing the foam, the difference between the average value of the diameters of the holes formed on the surface of each polishing pad and the difference in density are both ± 3%. If it is within the range, the average value of the pore diameters is the same among the plurality of polishing pads, and the proportion of the space occupied by the foaming is equivalent, so that variations in the polishing performance can be suppressed. The ratio of the hardness when immersed in water at a temperature of 70 ° C. for the same fixed time to the hardness when immersed in water at a temperature of 20 ° C. for a fixed time may be 80% or more.

The second aspect of the present invention is a chemical foaming which is an isocyanate group-containing compound, a polyamine compound, and is solid at room temperature and does not have an amide group and a hydrazide group and is thermally decomposed at 100 ° C. to 260 ° C. to generate a decomposition gas. and agents a, pyrolyzed at 100 ° C. to 260 ° C. has a solid at amide or hydrazide group at room temperature to generate a decomposition gas, and thermally decomposing temperature is thermally decomposed temperature of the chemical foaming agent a Is a preparation step for preparing a chemical foaming agent B having a difference of 5 ° C. or more respectively , and the blending ratio of the isocyanate group-containing compound, the polyamine compound, the chemical foaming agent A and the chemical foaming agent B is 50/50 to 20 / 80 combined mixture to be in the range of prepared and formation and foam-forming step of forming a foam from the mixture, the polishing pad by slicing the foam Suraisusu Tsu and up, a method for producing a polishing pad comprising a.

  In the second aspect, in the foam formation step, if a mixed solution is prepared by blowing a gas that is non-reactive with respect to the isocyanate group-containing compound, the polyamine compound, the chemical foaming agent A, and the chemical foaming agent B, the blown gas Since fine bubbles are generated, the chemical foaming agent A and the chemical foaming agent B can be dispersed substantially uniformly in the mixed solution. At this time, if the amount of gas blown is 0.5 to 3.4 liters per 1 kg of the total weight of the isocyanate group-containing compound, polyamine compound, chemical foaming agent A and chemical foaming agent B, Since the amount of the gas is limited, the formation of extremely large foam can be suppressed. Moreover, it is preferable to prepare a liquid mixture on the conditions of a shear rate of 9,000-41,000 / sec and the frequency | count of shear of 300-10,000 times in a foam formation step.

According to the present invention, the blending ratio of the chemical foaming agent A having no amide group or hydrazide group and the chemical foaming agent B having an amide group or hydrazide group is in the range of 50/50 to 20/80. , since the increase in viscosity of the mixture by a chemical foaming agent a, and decrease the viscosity of the mixture by chemical foaming agent B is less change in viscosity of the mixture is balanced, the dispersion state of the foam formed in the foam is equalized, because the pyrolysis temperature in a mixed chemical foaming agent a and a chemical foaming agent B in mixture has a difference of more than 5 ° C., the chemical foaming agent a, the thermal decomposition of the chemical blowing agent B separately It is easy to adjust the size and density of the foam by controlling it, and since the foam with a bipolar size is formed inside the foam, the surface of the polishing pad obtained by slicing is bipolar Openings with pore size distribution and almost even distribution Since the, the polishing liquid is stably supplied during polishing by the polishing pad, it is possible to improve the flatness of the object to be polished, it is possible to obtain an effect that.

  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 is a rigid foam type polyurethane sheet, and contains an isocyanate group-containing compound as a main component. The polishing pad 1 has a polishing surface P that comes into contact with the surface to be polished of the object to be polished through a slurry (polishing liquid) during polishing. The polishing pad 1 includes an isocyanate group-containing compound, a dispersion obtained by dispersing and diluting a chemical foaming agent A and a chemical foaming agent B in advance in a polyol compound, a polyamine compound, and each of these components (an isocyanate group-containing compound, a dispersion and a polyamine). It is formed by slicing a foam obtained by pouring a mixed liquid obtained by mixing a non-reactive gas (hereinafter abbreviated as non-reactive gas) with a compound into a mold. . That is, the polishing pad 1 is formed by dry molding.

Inside the polishing pad 1, during the dry molding, the two types of chemical foaming agents A and B in the mixed solution disperse the foam 3a and the foam 3b, which are substantially circular in cross section and bipolar in size, approximately evenly. Is formed. The formation of the foams 3a and 3b is caused by two types of chemical foaming agents A and B, respectively. Since the polishing pad 1 is formed of a slice of foam, a part of the foam 3a, 3b is opened on the polishing surface P, and the openings 4a, 4b are formed, respectively. Since the sizes of the foams 3a and 3b are different, the apertures 4a and 4b formed in the polishing surface P are bipolarized within a range of the pore diameter distribution of 3 to 500 μm. If opening 4a, the pore size distribution of 4b assumes a normal distribution, it is preferable that the center value of the opening 4b in the range of the center value of the aperture 4a ± sigma (standard deviation) are bipolarized in order not to fall it is preferable that the center value of the opening 4a in the range of the center value ± sigma of aperture 4b '(standard deviation) is bipolarized so as not to turn on. The thickness of the polyurethane sheet 2 is set in the range of 1.3 to 2.5 mm. This polyurethane sheet 2 has a wet hardness retention of 80 defined by the ratio of the hardness when immersed in water (hot water) at a temperature of 70 ° C. for the same fixed time with respect to the hardness when immersed in water at a temperature of 20 ° C. for a certain time. % Or more is set.

  Further, the polishing pad 1 has one side of a double-sided tape for attaching the polishing pad 1 to a polishing machine attached to the side opposite to the polishing surface P. In the double-sided tape, an adhesive is applied to both surfaces of the base material 7, and the release paper 8 is bonded to the other surface side (the lowermost surface side in FIG. 1). For the substrate 7, a film made of polyethylene terephthalate (hereinafter abbreviated as PET) is used.

(Manufacture of polishing pad)
The polishing pad 1 is manufactured through each process shown in FIG. That is, a preparation step (preparation step) for preparing an isocyanate group-containing compound, a chemical foaming agent A, a chemical foaming agent B, and a polyamine compound, respectively, and the chemical foaming agents A and B are dispersed and diluted in a polyol compound. A mixing process for preparing a mixed liquid by mixing an isocyanate group-containing compound, a dispersion, a polyamine compound and a non-reactive gas, a casting process for casting the mixed liquid into a mold, and foaming and curing in the mold A curing molding process (foam forming step) for forming a foam, a slicing process (slicing step) for slicing the foam into a sheet to form a plurality of polishing pads 1, and a polishing pad 1 and a double-sided tape It is manufactured through a laminating process for pasting together. Hereinafter, it demonstrates in order of a process.

(Preparation process)
In the preparation step, an isocyanate group-containing compound, a chemical foaming agent A, a chemical foaming agent B, and a polyamine compound are prepared.

  As an isocyanate group-containing compound, an isocyanate-terminated urethane prepolymer (hereinafter simply referred to as “isocyanate-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. Abbreviated as prepolymer). When the polyol compound and the diisocyanate compound are reacted, the prepolymer can be obtained by making the molar amount of the isocyanate group larger than the molar amount of the hydroxyl group. Moreover, when the prepolymer used has a too high viscosity, the fluidity is deteriorated and it becomes difficult to mix substantially uniformly during mixing. When the temperature is raised and the viscosity is lowered, the pot life is shortened, and on the contrary, the size of the foams 3a and 3b formed in the foam obtained by generating mixed spots is difficult to be polarized. On the other hand, if the viscosity is too low, the bubbles move in the mixed solution, and it becomes difficult to form the foams 3a and 3b dispersed substantially uniformly in the obtained foam. 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, 2,4-tolylene diisocyanate, naphthalene-1,4-diisocyanate, and diphenylmethane-4. , 4′-diisocyanate, 3,3′-dimethoxy-4,4′-biphenyl diisocyanate, 3,3′-dimethyldiphenylmethane-4,4′-diisocyanate, xylylene-1,4-diisocyanate, 4,4′-diphenyl Propane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate DOO, 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 chemical foaming agent A is a substance that is solid at room temperature and does not have an amide group or a hydrazide group in the molecule, and generates thermal decomposition gas at a temperature of 100 to 260 ° C. On the other hand, the chemical foaming agent B is a solid substance at room temperature having an amide group or a hydrazide group in the molecule, and, like the chemical foaming agent A, thermally decomposes at a temperature of 100 to 260 ° C. to generate a decomposition gas. The chemical foaming agent A and the chemical foaming agent B have different thermal decomposition temperatures.

  As the chemical foaming agent A, one or more selected from barium azodicarboxylate, N, N′-dinitrosopentamethylenetetramine and sodium hydrogen carbonate can be used. On the other hand, as the chemical foaming agent B, one or more selected from azodicarbonamide, 4,4′-oxybisbenzenesulfonyl hydrazide and hydrazodicarbonamide can be used. If the thermal decomposition temperature of the chemical foaming agents A and B is less than 100 ° C., there is a possibility that they will be thermally decomposed in the next mixing step or casting step, and if it exceeds 260 ° C., the urethane component may be thermally decomposed. is there. Further, the difference in thermal decomposition temperature between the chemical foaming agent A and the chemical foaming agent B is 5 to control the chemical foaming agents A and B individually (thermal decomposition) and to easily adjust the size and density of foaming. It is preferable that it is at least ° C, more preferably at least 10 ° C. In this example, the thermal decomposition temperature of the chemical foaming agent A is selected to be 17 ° C. lower than that of the chemical foaming agent B. Further, by adding a urea compound, a zinc compound, or the like as a so-called foaming aid, the foaming temperature may be appropriately adjusted to control the chemical foaming agents A and B.

  As the polyamine compound prepared in the preparation step, an aliphatic or aromatic polyamine compound can be used. For example, ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) and the like can be mentioned. Also, polyamine compounds having a hydroxyl group such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2- Hydroxypropylethylenediamine or the like can also be used.

(Mixing process, casting process, curing molding process)
As shown in FIG. 2, in the mixing step, the chemical foaming agent A and the chemical foaming agent B prepared in the preparation step are dispersed in a polyol compound, and the dispersion, the prepolymer, and the polyamine compound are mixed at the same time. A reactive gas is blown in to prepare a mixed solution. In the casting process, the liquid mixture prepared in the mixing process is cast into a mold, and in the curing molding process, the foam is formed by foaming and curing in the mold under a temperature condition where the chemical foaming agents A and B are thermally decomposed. To mold. In this example, a mixing process, a casting process, and a curing molding process are performed continuously.

  As the polyol compound for dispersing and diluting the chemical foaming agents A and B, compounds such as diol compounds and triol compounds can be used. For example, low molecular weight polyol compounds such as ethylene glycol and butylene glycol, polytetramethylene glycol, polyethylene, etc. Any of high molecular weight polyol compounds such as glycol and polypropylene glycol can be used. Since it becomes easy to uniformly disperse the chemical foaming agents A and B in the mixing step by setting the viscosity to the same level as the viscosity of the prepolymer or polyamine compound solution, it is preferable to use a polyol compound having a number average molecular weight of 500 to 2000, Polypropylene glycol having a number average molecular weight of 1000 to 2000 is more preferable from the viewpoint of dispersibility and the heat resistance of the resulting polishing pad. In this example, polypropylene glycol having a number average molecular weight of about 2000 is used, and chemical foaming agents A and B are each dispersed and diluted at a ratio of 1 to 20% by weight to prepare a dispersion. When preparing the dispersion, it may be stirred and mixed at room temperature using a general stirring device, and the chemical foaming agents A and B may be dispersed and diluted substantially evenly. The amount of the dispersion is preferably prepared so that the chemical foaming agents A and B are blended in an amount of 0.1 to 3.0% by weight in the mixed liquid obtained in the subsequent mixing step. If the blending amount of the chemical foaming agents A and B is too large, the density of the resulting foam will be too low. On the other hand, if the blending amount is too small, it will be difficult to control the pore size such that the pore size distribution becomes bipolar. For example, when the weight of the liquid mixture is 10 kg, if the dispersion liquid to be mixed is 1 to 2 kg, the amount of the chemical foaming agents A and B contained in this dispersion liquid is 0.01 to 0.3 kg. The compounding ratio of the chemical foaming agents A and B therein is 0.1 to 3.0% by weight.

  The chemical foaming agent A tends to increase the viscosity of the mixed solution to cause gelation. On the other hand, the chemical foaming agent B tends to reduce the viscosity of the mixed solution. For this reason, it is important to mix the chemical foaming agents A and B in a balanced manner. By setting the compounding ratio of the chemical foaming agents A and B in the range of 50/50 to 20/80, it is possible to reduce the viscosity change of the mixed solution. In order to further suppress the viscosity change of the mixed solution, it is preferable to set the blending ratio to 40/60 to 30/70.

  As shown in FIG. 3, in the mixing step, a mixed solution is prepared by the mixer 20, and in the casting step, the prepared mixed solution is continuously cast from the mixer 20 into the mold 25 and cured in the curing molding step. By doing so, the foam is molded. The mixer 20 includes a mixing tank 12 in which a stirring blade 14 is incorporated. On the upstream side of the mixing tank 12, a prepolymer as the first component, a polyamine compound as the second component, a supply tank containing the dispersion as the third component, and a supply for supplying the non-reactive gas into the mixing tank 12 A device 16 is arranged. The supply port from each supply tank is connected to the upstream end of the mixing tank 12, and the supply port of the non-reactive gas from the supply device 16 is approximately from the upstream end to the entire length of the mixing tank 12. It is connected to the 1/3 position. The stirring blade 14 is fixed to a rotating shaft arranged from the upstream side to the downstream side at a substantially central portion in the mixing tank 12. As the rotating shaft rotates, the stirring blade 14 rotates to mix the first component, the second component, the third component, and the non-reactive gas so as to shear. The obtained mixed liquid is poured into the mold 25 from a discharge port arranged at the downstream end of the mixing tank 12. The upper part of the mold 25 is open, and in this example, the size is set to 1050 mm (length) × 1050 mm (width) × 50 mm (thickness).

  Since most of the prepolymer of the first component and the polyamine compound of the second component are both solid or difficult to flow at normal temperature, each supply tank is heated so that each component can flow. The temperature at this time is set to a temperature at which the chemical blowing agents A and B dispersed and diluted in the third component dispersion are not thermally decomposed. Further, in order to prevent moisture contained in the non-reactive gas from participating in the reaction in the mixing tank 12, the non-reactive gas from the supply device 16 is removed by a moisture removing device (not shown). Yes. The supplied non-reactive gas becomes fine bubbles by the rotation of the stirring blade 14 in the mixing tank 12, and these bubbles disperse the dispersion obtained by dispersing and diluting the chemical foaming agents A and B substantially uniformly in the mixed solution. Demonstrate bubbling effect. If the supply amount of the non-reactive gas is too small, the bubbling effect is insufficient and the dispersion state of the chemical foaming agents A and B tends to be biased. Conversely, if the amount is too large, extremely large bubbles are generated in the foam. . For this reason, it is preferable to adjust the supply amount of a non-reactive gas so that it may become a ratio of 0.5-3.4 liter with respect to 1 kg of total weight of a prepolymer, a polyamine compound, and the chemical foaming agents A and B. Examples of the non-reactive gas include air, nitrogen, oxygen, carbon dioxide, helium, and argon.

  The first component, the second component, and the third component are supplied from each supply tank to the mixing tank 12, and the non-reactive gas is supplied from the supply device 16 after being mixed to some extent by the stirring blade 14. By adjusting the shearing speed and the number of times of shearing of the stirring blade 14, the components and the non-reactive gas are mixed almost uniformly to prepare a mixed solution. If the shear rate of the stirring blade 14 is too low, it is difficult to control the size of the foams 3a and 3b formed in the resulting foam, and the pore size distribution is difficult to be polarized. On the other hand, if the shear rate is too high, the temperature rises due to the heat generated by friction between the stirring blade 14 and the mixed solution and the viscosity decreases, so that bubbles in the mixed solution move (during molding) and foam is obtained. Variations in the dispersion state of the foams 3a and 3b formed in the body are likely to occur. On the other hand, if the number of times of shearing is too small, unevenness (variation) is likely to occur in the size of the generated bubbles. On the other hand, if the number of shearing is too large, the viscosity decreases as the temperature rises, and foams 3a and 3b are not formed substantially uniformly. Moreover, the chemical foaming agents A and B may be thermally decomposed by the temperature rise during mixing. For this reason, in a mixing process, a shear rate is set to the range of 9,000-41,000 / sec, and the frequency | count of shear is set to the range of 300-10,000 times, and it mixes. The mixing time (residence time) in the mixer 20 is about 1 second although it depends on the flow rate of the mixed liquid (maximum 1 liter / sec). That is, for example, the time required to inject the mixed solution into the mold 25 of about 100 kg in the injecting step is about 1 to 2 minutes. In addition, a shear rate and the frequency | count of shear can be calculated | required by following Formula. That is, shear rate (/ sec) = diameter (mm) of blade tip of stirring blade 14 × circularity × rotational speed (rpm) of stirring blade 14 ÷ 60 ÷ blade tip of stirring blade 14 and inner wall of mixing vessel 12 Clearance (mm), number of times of shearing (times) = rotation speed of stirring blade 14 (rpm) ÷ 60 × retention time of mixed solution in mixing tank 12 (second) × number of blades of stirring blade 14 Can do.

  When injecting the mixed liquid into the mold 25 in the liquid injection process, the mixed liquid from the mixer 20 is discharged from the discharge port of the mixing tank 12, for example, between two opposing sides of the mold 25 through a flexible pipe. Liquid is introduced into a liquid injection port (not shown) having a triangular cross section that reciprocates (for example, between the left and right in FIG. 3). While reciprocating the liquid injection port, the end of the discharge port (the end of the flexible pipe) is reciprocated in a direction intersecting the direction of movement of the liquid injection port. The mixed liquid is poured into the mold 25 substantially evenly.

  In the curing molding process, the injected liquid mixture is reacted in the mold 25 to form a foam. At this time, the prepolymer is crosslinked and cured by the reaction between the prepolymer and the polyamine compound in the mixed solution. Since the upper part of the mold 25 is open, the cross-linking and curing proceeds under atmospheric pressure, and a foam is formed. Since reaction heat is generated with the progress of this crosslinking and curing, the temperature in the mold 25 increases. When the temperature in the mold 25 reaches the thermal decomposition temperature of the chemical foaming agents A and B, the chemical foaming agents A and B are thermally decomposed to generate a decomposition gas (nitrogen gas or the like). When the thermal decomposition temperature of the chemical foaming agents A and B is higher than the temperature raised by the reaction heat, the chemical foaming agents A and B are thermally decomposed by heating from the outside of the mold 25. Since the cross-linking and curing of the prepolymer proceeds, the generated decomposition gas does not escape to the outside, and the foams 3a and 3b are formed. Since the thermal decomposition temperature of the chemical foaming agent A is 17 ° C. lower than that of the chemical foaming agent B, the chemical foaming agent A is thermally decomposed earlier than the chemical foaming agent B and generates a decomposition gas as the temperature in the mold 25 rises. At this point, the cross-linking curing has not progressed sufficiently, and a large foam 3a is formed. As the temperature in the mold 25 further rises, the chemical foaming agent B is thermally decomposed to generate decomposition gas. At this time, since the hardness of the prepolymer is increased by the progress of the cross-linking curing, the spread of the decomposition gas is limited, and a small foam 3b is formed. In addition, foam 3a, 3b is formed in various shapes, such as circular shape and elliptical shape, in cross-sectional shape. In addition, the generated decomposition gas is non-reactive with the prepolymer and the polyamine compound, and is dissipated at the time of opening, so that it does not affect the crosslinking curing reaction or the polishing pad 1 at all.

(Slicing process)
As shown in FIG. 2, in the slicing step, the foam obtained in the curing molding step is sliced into a sheet shape to form a plurality of polishing pads 1. A general slicing machine can be used for slicing. At the time of slicing, the lower layer portion of the foam 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. Moreover, in the foam molded by 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 foam is not used due to scratches and the like. 10 to 25 polishing pads 1 are formed from 30 mm. Since a foamed body in which the foams 3a and 3b are substantially uniformly formed is obtained in the curing molding process, the diameters of the openings 4a and 4b formed on the surface of the plurality of polishing pads 1 formed in the slicing process are obtained. All distributions are polarized within a range of 3 to 500 μm. In addition, since the foams 3a and 3b are formed to be substantially evenly dispersed inside the foam, in each polishing pad 1, the difference in the average value of the hole diameters of the openings 4a and 4b is within a range of ± 3%, and the density The difference is within a range of ± 3%.

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

  When polishing an object to be polished, the polishing pad 1 is mounted on a polishing surface plate of a polishing machine. When the polishing pad 1 is mounted on the polishing surface plate, the release paper 8 is removed, and the surface is adhered and fixed to the polishing surface plate with the exposed adhesive layer. The surface to be polished (surface to be polished) is polished by rotating the polishing platen while applying pressure to the object to be polished and supplying slurry.

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

  In this embodiment, in the mixing step, a prepolymer, a dispersion obtained by dispersing and diluting the chemical foaming agents A and B in advance with a polyol compound, and a polyamine compound are mixed, and at the same time, a non-reactive gas is blown to prepare a mixed solution. The For this reason, fine bubbles are generated by the blown non-reactive gas, and the chemical foaming agents A and B in the dispersion liquid are dispersed substantially uniformly in the liquid mixture. In other words, the polyol compound in the dispersion serves to facilitate the dispersion of the chemical foaming agents A and B in the mixed solution. Since the dispersion liquid is dispersed in the mixed liquid by bubbles generated by the non-reactive gas, the dispersion state of the chemical foaming agents A and B in the mixed liquid can be equalized. The chemical foaming agents A and B are thermally decomposed to generate a decomposition gas, whereby foams 3a and 3b having a bipolar size and dispersed almost uniformly inside the obtained foam can be formed. Therefore, by slicing in the slicing step, it is possible to obtain the polishing pad 1 in which the holes 4a and 4b having the pore diameter distribution polarized on the surface are formed substantially evenly. In this polishing pad 1, slurry is held in the openings 4 a and 4 b during polishing, and polishing scraps are mainly accommodated in the openings 4 a, so that the slurry is supplied substantially evenly and polishing scraps are interposed on the polishing surface. Accordingly, the flatness of the object to be polished can be improved, and the deterioration of the polishing performance can be suppressed.

  In this embodiment, a part of polypropylene glycol (polyol compound) added to the dispersion for the purpose of improving the dispersibility of the chemical foaming agents A and B in the mixed solution forms a urethane bond with the isocyanate group-containing compound. . For this reason, in the obtained polishing pad 1, since heat-and-moisture resistance improves, even if it heat | fever-generates with grinding | polishing processing, the fall of polishing efficiency can be suppressed.

  Furthermore, in this embodiment, since the mixing step, the casting step, and the curing molding step are continuously performed, the curing reaction is performed before the chemical foaming agents A and B dispersed substantially uniformly in the mixed solution cause aggregation or the like. Progresses. For this reason, the foams 3a and 3b resulting from the decomposition gas of the chemical foaming agents A and B can be substantially uniformly dispersed inside the foam.

  Furthermore, in this embodiment, each substance is selected so that the thermal decomposition temperature of the chemical foaming agent A is 17 ° C. lower than that of the chemical foaming agent B. Since the difference in thermal decomposition temperature is 17 ° C., there is a difference in the timing of generating decomposition gas by thermal decomposition during curing molding. At the same time, the cross-linking and curing reaction of the prepolymer is proceeding. The hardness of the prepolymer at the time will be different. For this reason, since the spread of the generated cracked gas is limited, a difference occurs in the size of the formed foam. That is, even when the chemical foaming agent A and the chemical foaming agent B generate the same amount of decomposition gas, when the chemical foaming agent A having a low thermal decomposition temperature is thermally decomposed, the decomposition gas sufficiently spreads to form a large foam 3a. On the other hand, when the chemical foaming agent B having a high thermal decomposition temperature is thermally decomposed, the spread of the decomposition gas is limited by the prepolymer having increased hardness, and a small foam 3b is formed. Thereby, foam 3a, 3b with which the magnitude | size was bipolarized can be formed. By selecting the chemical foaming agents A and B, the size of the foams 3a and 3b can be controlled, and the polishing pad 1 in which the pore diameter distribution of the openings 4a and 4b is bipolar can be obtained.

  Furthermore, in this embodiment, the compounding ratio of the chemical foaming agents A and B is set in the range of 50/50 to 20/80. The liquid mixture containing the chemical foaming agent A tends to increase in viscosity and gel, and the liquid mixture containing the chemical foaming agent B tends to decrease in viscosity. By setting the blending ratio of the chemical foaming agents A and B in the above-described range, the chemical foaming agents A and B can be blended in a well-balanced manner and the viscosity change of the mixed liquid can be reduced. Thereby, each component can be mixed substantially uniformly in the mixing step, and the foams 3a and 3b can be formed in a substantially uniformly dispersed state without causing a bias in the curing molding step.

  Moreover, in this embodiment, the chemical foaming agents A and B in a dispersion liquid are mix | blended with sufficient balance, and it can be made to form in the state disperse | distributing foam 3a, 3b substantially equally. As a result, in the plurality of polishing pads 1 obtained by slicing, the hole diameter distribution of the openings 4a and 4b can be bipolarized within a range of 3 to 500 μm. Accordingly, the polishing scraps are accommodated in the apertures 4b while the slurry is held in the apertures 4a and 4b during the polishing process, so that the polishing efficiency can be improved. Further, the amount of the non-reactive gas supplied to the mixing tank 12 in the mixing step is set to a ratio of 0.5 to 3.4 liters with respect to 1 kg of the total weight of the prepolymer, the dispersion, and the polyamine compound, so that the mixed solution Since the amount of the non-reactive gas therein is limited, the chemical foaming agents A and B can be dispersed substantially evenly, and the foams 3a and 3b can be formed substantially evenly inside the obtained foam. Furthermore, by setting the viscosity of the prepolymer at a temperature of 50 to 80 ° C. in the range of 500 to 4000 mPa · s, the bubbling effect due to the non-reactive gas supplied in the mixing process is almost uniformly generated, and chemical foaming in the mixed solution The dispersion state of the agents A and B can be equalized. Thereby, the deviation of foam 3a, 3b inside the obtained foam can be suppressed, and it can disperse | distribute substantially uniformly. In addition, by setting the shear rate and the number of shears to the above-described conditions in the mixing step, the chemical foaming agents A and B in the dispersion are dispersed almost evenly, so that the dispersion state of the foams 3a and 3b is equalized. can do.

  Furthermore, a foam in which the foams 3a and 3b are formed substantially uniformly by preparing a dispersion in which the chemical foaming agents A and B are dispersed in the polyol compound in the preparation step in advance and supplying air in the mixing step. Therefore, in the plurality of polishing pads 1 formed in the slicing step, the difference in average value of the hole diameters of the openings 4a and 4b formed on the respective surfaces and the difference in (apparent) density are both ± It can be in the range of 3%. When the variation in the hole diameter becomes large, the openings 4a and 4b are likely to be locally clogged by abrasive grains (polishing particles) and polishing debris in the slurry during polishing, and the flatness of the object to be polished is lowered. . Further, since the hardness becomes too small (soft) when the density is reduced, it is difficult to improve the flatness of the object to be polished. On the contrary, if the density is increased, the hardness becomes too high, so that the polishing efficiency is lowered and the object to be polished is easily damaged. In this embodiment, since the hole diameters of the openings 4a and 4b of each polishing pad 1 are equal, local clogging can be suppressed. Moreover, since the ratio of the space occupied by the foams 3a and 3b in each polishing pad 1 is equal and the hardness is also equal, even if the polishing pad 1 is replaced, it is possible to suppress the occurrence of variations in polishing performance.

  Furthermore, the polyol compound blended in the dispersion serves to facilitate the dispersion of the chemical foaming agents A and B in the mixed solution. However, since the polyol compound exists in the mixed solution, the hydroxyl group of the polyol compound is a prepolymer. By reacting with an isocyanate group to form a urethane bond, it also plays a role of making it difficult to change the hardness of the foam in a wet state. For this reason, all the obtained polishing pads 1 have a wet hardness retention of 80% or more. In particular, wet hardness retention can be improved by using polypropylene glycol as the polyol compound. Therefore, since the thermal stability in a wet state is improved, even if heat is generated due to friction or the like during polishing using a slurry, the change in hardness of the polishing pad 1 is suppressed, and the polishing performance can be stabilized.

  Furthermore, as described above, the polishing pad 1 is formed by slicing a foam formed by equalizing the dispersion state of the foams 3a and 3b with the two types of chemical foaming agents A and B. In addition to the improvement, the flatness of the object to be polished can be improved, the thermal stability (wet hardness retention rate) is excellent, clogging is difficult, and the life can be improved. In addition, by increasing the size of the foam (increasing the formwork 25), it is possible to easily meet the demand for larger size (area, thickness).

  In the present embodiment, the example in which the difference in the thermal decomposition temperature between the chemical foaming agent A and the chemical foaming agent B is 17 ° C. is shown, but the present invention is not limited to this, and the difference in the thermal decomposition temperature. Is 5 ° C. or higher, a bipolar pore size distribution can be obtained. Moreover, you may make it the generation amount of the decomposition gas generated at the time of thermal decomposition of the chemical foaming agents A and B differ. When there is no difference in the thermal decomposition temperature between the chemical foaming agent A and the chemical foaming agent B, or when the difference in thermal decomposition temperature is less than 5 ° C., it becomes difficult to control the reaction depending on the temperature, but the chemical foaming agents A and B If the generation amount of the cracked gas generated during the thermal decomposition of is different, foaming with a bipolar pore size distribution can be formed. In this case, the generation amount of the decomposition gas of the chemical foaming agents A and B is preferably 1.1 times or more, more preferably 1.2 times or more of the other.

  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. In this embodiment, an example of preparing a dispersion in which the chemical foaming agents A and B are dispersed and diluted in a polyol compound has been shown. However, the present invention is not limited to this, and the dispersion is not limited to the polyol compound and the chemical. In addition to the foaming agents A and B, for example, components such as additives necessary for curing molding may be included. Moreover, you may make it mix the chemical foaming agents A and B directly, without making it a dispersion liquid. In view of equalizing the dispersion state of the foams 3a and 3b, it is preferable to prepare a dispersion in advance.

  Furthermore, in this embodiment, although the specific substance was illustrated as chemical foaming agent A and B, respectively, this invention is not limited to these. As the chemical foaming agent A, a substance that does not have an amide group and a hydrazide group in the molecule and is solid at room temperature that generates thermal decomposition gas at a temperature of 100 to 260 ° C. can be used. The chemical foaming agent B has an amide group or a hydrazide group in the molecule, and is a solid substance at normal temperature that is thermally decomposed at a temperature of 100 to 260 ° C. to generate a decomposition gas. A substance different from the chemical foaming agent A in the generation amount of decomposition gas at the time of decomposition can be used.

  Furthermore, although not particularly mentioned in the present embodiment, the polishing surface P of the polishing pad 1 may be grooved in consideration of supply of slurry and discharge of polishing debris. The shape of the groove may be any of a radial shape, a lattice shape, and a spiral shape, and the cross-sectional shape may be any of a rectangular shape, a U shape, a V shape, and a semicircular shape. The pitch, width, and depth of the grooves are not particularly limited as long as the polishing waste can be discharged and the slurry can be moved.

  Furthermore, in the present embodiment, an example in which the mixer 20 is used in the mixing process and the slicing machine is used in the slicing process, but there is no particular limitation on the mixer or slicing machine. Can be used. In the present embodiment, the rectangular parallelepiped mold 25 is illustrated, but the present invention is not limited to the shape and size of the mold. For example, a cylindrical form or the like may be used, and the foam may be formed without using the form if the viscosity of the mixed liquid is taken into consideration. In the present embodiment, the example in which the liquid is poured from the mixer 20 into the mold 25 and molded under the atmospheric pressure is shown, but the present invention is not limited to this. For example, the liquid mixture may be prepared in a container and cured and molded in the container, or the container may be sealed and cured and molded under pressure. Furthermore, in the present embodiment, an example in which the chemical foaming agents A and B are thermally decomposed by reaction heat accompanying cross-linking curing has been shown, but it may be positively heated from the outside. Further, by preheating the mold 25 at the time of pouring the mixed liquid (for example, about 25 ° C.), it becomes difficult to be affected by the environmental temperature, and the cured molding can be stabilized.

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

Example 1
In Example 1, a urethane prepolymer containing terminal isocyanate groups (Adiprene L-325) having an isocyanate content of 9 to 9.3% was used as the prepolymer of the first component, which was heated to 55 ° C. and degassed under reduced pressure. . Propylenediamine was used as the second component and degassed under reduced pressure. The third component dispersion was prepared by adding 50 parts of polypropylene glycol having a number average molecular weight of about 2000 to N, N′-dinitrosopentamethylenetetramine (thermal decomposition temperature: 123 ° C., generation amount of decomposition gas: 125 ml / 8 parts of g), 8 parts of azodicarbonamide (thermal decomposition temperature 140 ° C., generation amount of cracked gas 135 ml / g) as chemical foaming agent B, 1 part of catalyst (Toyocat ET, manufactured by Tosoh Corporation), silicon-based Two parts of a surfactant (SH-193, manufactured by Dow Corning) were added and mixed with stirring, and then degassed under reduced pressure. That is, between the chemical foaming agent A and the chemical foaming agent B, there is a difference of 10 ml / g in the generation amount of the decomposition gas, and the thermal decomposition temperature of the chemical foaming agent A is set 17 ° C. lower than the thermal decomposition temperature of the chemical foaming agent B. Has been. The 1st component: 2nd component: 3rd component was supplied to the mixing tank 12 by the ratio of 100 parts: 22.8 parts: 5.3 parts by weight ratio. In the mixing step, the stirring conditions were set to a shear rate of 1689 times and a shear rate of 9425 / second. At this time, air was supplied into the mixing tank 12 at a flow rate of 80 L / min. The obtained mixed liquid was poured into a mold 25 and cured, and then the formed foam was extracted from the mold 25. This foam was sliced to a thickness of 1.3 mm to produce a polishing pad 1.

(Comparative Example 1 and Comparative Example 2)
In Comparative Example 1, a polishing pad was prepared in the same manner as in Example 1 except that only the chemical foaming agent A was mixed as it was (without being dispersed and diluted in polypropylene glycol) in the mixing step. In Comparative Example 2, a polishing pad was produced in the same manner as in Example 1 except that only the chemical foaming agent B was mixed as it was (without being dispersed and diluted in polypropylene glycol) in the mixing step.

(Evaluation)
About the Example and the comparative example, the density of the polishing pad 1 obtained by slicing from the upper layer part of the cured molded foam, the center part, and the lower layer part, the hole diameter of the polishing surface P, the hole diameter distribution, and the polishing characteristics were measured. The density was calculated from the volume obtained from the size obtained by measuring the weight of the sample cut into a predetermined size. The opening diameter and the hole diameter distribution were 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) processed and calculated. Moreover, about the polishing pad 1 obtained from the center part, wet (WET) hardness and hardness retention were measured. The wet hardness was determined by immersing the polishing pad 1 in water at a temperature of 20 ° C. for 30 minutes, and then measuring the Shore A hardness as the hardness according to Japanese Industrial Standard (JIS K 7311). After immersing the same polishing pad 1 in hot water at a temperature of 70 ° C. for 30 minutes, the Shore A hardness was measured in the same manner, and the ratio of the hardness at 70 ° C. to the hardness at 20 ° C. was obtained as a percentage. For the evaluation of the polishing characteristics, the polishing pad 1 prepared in a polishing apparatus (manufactured by Fujikoshi Machine Industry Co., Ltd., MCP-150X) was attached and polishing was performed, and the polishing rate was measured. The polishing rate was the amount of weight reduction per unit time when polishing was performed 20 times on an 8-inch silicon wafer with a polishing time of 30 minutes. The polishing conditions were as follows. That is, silica slurry (Cabot Corp., SS12) was used as the slurry and supplied at a flow rate of 650 ml / min during polishing. At this time, the polishing load was set to 350 g / cm ² , the polishing platen rotation speed was 100 rpm, and the wafer rotation speed was 75 rpm. The results of density and pore diameter are shown in Table 1 below, and the results of wet hardness, hardness retention and polishing properties are shown in Table 2 below.

  As shown in Table 1, Comparative Example 1 in which foaming was formed only with chemical foaming agent A and Comparative Example 2 in which foaming was formed only with chemical foaming agent B showed a single pore size distribution. However, since there are variations in density and pore diameter in the upper layer portion, the center portion, and the lower layer portion of the obtained foam, it is conceivable that the dispersion state of the foam is uneven. On the other hand, in Example 1 in which the chemical foaming agent A and the chemical foaming agent B were previously dispersed in polypropylene glycol and the foams 3a and 3b were formed, the upper layer portion, the central portion, and the lower layer portion The density and the aperture diameter were found to be substantially uniform (within ± 3%). Further, the measurement results of the pore size distribution showed a bipolar pore size distribution in which the center value of the pore size is a distribution of 35 μm and a distribution of 68 to 70 μm. At this time, the pore size distribution was assumed to be a normal distribution, and it was confirmed that each of the center values did not fall within the range of the center value ± σ (standard deviation). From this, by performing polishing with the resulting polishing pad 1, clogging is suppressed while the slurry is held in the openings 4a and 4b having a bipolar hole diameter distribution, and the flatness of the object to be polished is improved. You can expect

  As shown in Table 2, in Comparative Examples 1 and 2, although the hardness retention is 80% or more, the polishing characteristics are inferior. On the other hand, in Example 1, since the wet hardness is 84 degrees and the hardness retention rate is 89% (80% or more), not only the hardness change that occurs during the polishing process is suppressed. Further, it was found that since the opening diameter is bipolar, the polishing characteristics are also excellent.

  From the above results, the prepolymer, a dispersion obtained by dispersing and diluting the chemical foaming agents A and B in advance in polypropylene glycol, and propylene diamine are mixed, and air is blown to prepare a mixed solution. Can be obtained by substantially uniformly dispersing foam formed by slicing the foam, and slicing the foam to obtain a polishing pad having pores with a pore diameter distribution formed on the surface substantially uniformly. It turns out that you can. Therefore, clogging can be suppressed by sufficiently holding the polishing debris while reliably holding the slurry, and the flatness of the object to be polished can be improved. Moreover, it became clear that the dispersion | variation in polishing performance can be suppressed by the grinding | polishing process by the several polishing pad obtained from one foam.

  The present invention provides a polishing pad that can stably supply a polishing liquid and improve the flatness of an object to be polished, and a method for manufacturing the polishing pad. With the availability of

It is sectional drawing which shows the polishing pad of embodiment to which this invention is applied. 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

DESCRIPTION OF SYMBOLS 1 Polishing pad 3a, 3b Foam 4a, 4b Open hole P Polishing surface 20 Mixer

Claims (12)

An isocyanate group-containing compound, a polyamine compound, a chemical foaming agent A that is solid at room temperature, has no amide group and hydrazide group, and decomposes at 100 ° C. to 260 ° C. to generate decomposition gas, and is solid at room temperature by thermal decomposition at 100 ° C. to 260 ° C. has an amide group or hydrazide group decomposition gas generated, chemical pyrolysis temperature is to have a difference of more than 5 ° C. the thermal decomposition temperature of the chemical foaming agent a A polishing pad obtained by slicing a foam formed from a mixed solution obtained by mixing a foaming agent B with a blending ratio in a range of 50/50 to 20/80 .   The chemical foaming agent A is one or more selected from barium azodicarboxylate, N, N′-dinitrosopentamethylenetetramine and sodium hydrogen carbonate, and the chemical foaming agent B is azodicarbonamide, 4, The polishing pad according to claim 1, wherein the polishing pad is one or more selected from 4'-oxybisbenzenesulfonyl hydrazide and hydrazodicarbonamide.   2. The chemical foaming agent A and the chemical foaming agent B are mixed in the mixed liquid as a dispersion liquid in which the polyol compound is preliminarily dispersed and diluted at a ratio of 1 wt% to 20 wt%, respectively. The polishing pad described in 1.   The polishing pad according to claim 3, wherein the polyol compound is polypropylene glycol.   2. The polishing pad according to claim 1, wherein the isocyanate group-containing compound has a viscosity at a temperature of 50 ° C. to 80 ° C. in a range of 500 mPa · s to 4000 mPa · s. Openings are formed on the surface by the slice of the foam, and the pore size distribution of the apertures is bipolarized within a range of 3 μm to 500 μm , and when each pore size distribution is assumed to be a normal distribution, The center value in one hole diameter distribution is outside the range of the center value ± standard deviation in the other hole diameter distribution, and the center value in the other hole diameter distribution is outside the range of the center value ± standard deviation in the one hole diameter distribution the polishing pad according to claim 1, characterized in that.   When a plurality of polishing pads are formed by slicing the foam, each of the openings formed on the surface of each polishing pad has a difference in average value of hole diameters and a difference in density of ± 3%. The polishing pad according to claim 1, wherein the polishing pad is within a range.   2. The polishing pad according to claim 1, wherein the ratio of the hardness when immersed in water at a temperature of 70 ° C. for 80 hours or more to the hardness when immersed in water at a temperature of 20 ° C. for a certain time is 80% or more. . An isocyanate group-containing compound, a polyamine compound, a chemical foaming agent A that is solid at room temperature, has no amide group and hydrazide group, and decomposes at 100 ° C. to 260 ° C. to generate decomposition gas, and is solid at room temperature by thermal decomposition at 100 ° C. to 260 ° C. has an amide group or hydrazide group decomposition gas generated, chemical pyrolysis temperature is to have a difference of more than 5 ° C. the thermal decomposition temperature of the chemical foaming agent a A preparation step of preparing each of foaming agent B;
A mixed liquid prepared by mixing the isocyanate group-containing compound, the polyamine compound, the chemical foaming agent A and the chemical foaming agent B so that the blending ratio is in the range of 50/50 to 20/80 is prepared. Forming a foam, and
Slicing the foam to form a polishing pad;
A method for producing a polishing pad comprising:   10. The mixed liquid is prepared by blowing a non-reactive gas into the isocyanate group-containing compound, the polyamine compound, the chemical foaming agent A, and the chemical foaming agent B in the foam forming step. The manufacturing method as described.   The amount of gas blown in the foam forming step is a ratio of 0.5 to 3.4 liters with respect to 1 kg of the total weight of the isocyanate group-containing compound, polyamine compound, chemical foaming agent A and chemical foaming agent B. The manufacturing method according to claim 10.   The manufacturing method according to claim 9, wherein, in the foam formation step, the mixed solution is prepared under conditions of a shear rate of 9,000 to 41,000 / sec and a shear rate of 300 to 10,000.

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