JP5072442B2 - Polishing pad manufacturing method and polishing pad - Google Patents

Description

  The present invention relates to a method for producing a polishing pad and a polishing pad, and more particularly to a method for producing a polishing pad containing an isocyanate group-containing compound as a main component and a polishing pad obtained by the production method.

  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, the surface to be polished (surface to be polished) is pressed against the polishing pad, and a slurry 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.

Various techniques have been disclosed for forming foam inside when molding a foam of rigid polyurethane foam. For example, there is a technique of internally adding hollow fine particles during molding (see Patent Document 1, Patent Document 2, and Patent Document 3). In addition, as a technique for forming foam by adding water at the time of molding, a technique of a polishing pad in which a composition of an isocyanate group-containing compound and an active hydrogen compound is determined to form a foam having a diameter of 50 to 150 μm (see Patent Document 4), Polishing pad technology in which the average diameter of small foams having a foam diameter of less than 400 μm is 20 to 100 μm and large foams having a foam diameter of 400 to 1000 μm are formed to 10 to 100/100 cm ² to improve the slurry holding performance (Patent Document 5) Reference). Furthermore, as a technique for forming foam by enclosing an inert gas at the time of molding, a silicon-based activator is added so that the number of independent foams is 200 to 600 / mm ² and the average foam diameter is 30 to 60 μm. Pad technology (see Patent Document 6), polishing pad technology in which the average value of the diameters of the openings is 1 to 50 μm and at least 1000 holes / cm ² or more of the diameters of 0.1 to 10 μm are formed (patent) Reference 7), and a polishing pad technique (see Patent Document 8) in which unevenness of pore diameter is reduced at an average pore diameter of 70 μm or less by adjusting the viscosity and activation energy of the isocyanate group-containing compound.

Japanese Patent No. 3013105 Japanese Patent Laid-Open No. 11-322877 Japanese Patent Laid-Open No. 11-322878 JP 2005-68168 A JP 2006-210657 A Japanese Patent No. 3455208 JP 2004-188586 A JP 2006-257178 A

  However, in the techniques of Patent Documents 1 to 3, since the components of the hollow fine particles are present as contaminants between the surface to be polished and the polishing pad at the time of polishing, it is unexpected due to the slurry used. May cause adverse effects. In this respect, the techniques of Patent Documents 4 to 8 do not use hollow fine particles, so that the influence of foreign substances can be prevented. However, in the techniques of Patent Document 4 and Patent Document 5, although foaming is formed by adding water, it is difficult to equalize the dispersion state of water. However, there is a problem that a difference is likely to occur. For this reason, the polishing performance varies among a plurality of polishing pads obtained from one foam. In the technique of Patent Document 5, since large foam is formed in addition to small foam, an improvement in slurry holding performance can be expected, but the addition of water alone causes variations in the formation of large foam (unevenness in arrangement). Since clogging is likely to occur in the small foam, the polishing performance varies and the life of the polishing pad is reduced. In order to eliminate clogging, the polishing process can be interrupted and the surface can be dressed (surface sanding), but the polishing workability is reduced. In the techniques of Patent Document 6 to Patent Document 8, if the foam has an average pore diameter of about several μm, it is easier to control than the formation of foam by water. There is a problem that it is difficult.

  An object of the present invention is to provide a polishing pad manufacturing method in which apertures are formed substantially uniformly and substantially uniformly and variation between polishing pads is suppressed, and a polishing pad obtained by the manufacturing method. .

In order to solve the above problems, a first aspect of the present invention is a method for producing a polishing pad comprising an isocyanate group-containing compound as a main component, wherein 1 wt% of water is added to the isocyanate group-containing compound and the polyol compound in advance. A preparation step of preparing a dispersion liquid that has been dispersed and diluted at a ratio of ˜6% by weight and a polyamine compound, mixing the isocyanate group-containing compound, the dispersion liquid, and the polyamine compound, and mixing the isocyanate group-containing compound and the dispersion A non-reactive gas with respect to the liquid and the polyamine compound to prepare a mixed solution, a foam forming step to form a foam from the mixed solution, and a plurality of sheets obtained by slicing the foam look containing a slice forming a polishing pad, a polishing pad formed in the slice step , For the hardness when both were given time immersed in a temperature 20 ° C. water, the percentage of hardness when immersed the predetermined time in water at a temperature 70 ° C. is equal to or less than 80%.

In the first aspect, in the mixed solution preparation step, the isocyanate group-containing compound, the dispersion obtained by dispersing and diluting water in advance in the polyol compound, and the polyamine compound are mixed, and a gas is blown to prepare a mixed solution. Fine bubbles are generated by the gas, and the water in the dispersion liquid that has been pre-dispersed and diluted is dispersed almost evenly in the liquid mixture, so that foam is formed that is controlled in size and is evenly dispersed inside the foam. Therefore, by slicing in the slicing step, it is possible to obtain a plurality of polishing pads in which substantially uniform openings are formed substantially uniformly on the surface, and the polishing performance by each polishing pad is suppressed. it is possible, polishing pad was obtained, with respect to the hardness when either a predetermined time immersed in a temperature 20 ° C. water, the same constant water temperature 70 ° C. The proportion of the hardness of 80% or more upon during immersion, the hardness in the wet state even if heating by friction during polishing using a slurry is hard to change, it is possible to suppress a decrease in polishing performance .

  In the first aspect, the mixed solution preparation step and the foam formation step may be performed continuously. If the amount of water to be dispersed and diluted in the dispersion liquid in the preparation step is set to a ratio of 1 g to 6 g with respect to 1 kg of the isocyanate group-containing compound, the amount of water is limited, so that the formation and bias of large foaming is suppressed. can do. Further, if the amount of gas blown into the mixed liquid in the mixed liquid preparation step is set to a ratio of 0.5 L to 3.4 L with respect to 1 kg of the total weight of the isocyanate group-containing compound, the dispersion liquid and the polyamine compound, Since the amount of gas is limited, the formation of extremely large foam can be suppressed. If the polyol compound in the preparation step is made of polypropylene glycol, the unevenness of foaming hardly occurs and the wet heat resistance of the polishing pad can be improved. If the viscosity at a temperature of 50 ° C. to 80 ° C. of the isocyanate group-containing compound prepared in the preparation step is in the range of 500 mPa · s to 4000 mPa · s, the movement of foaming is suppressed in the mixed solution, so the foaming bias is Can be suppressed. In the mixed solution preparation step, it is preferable to prepare the mixed solution under conditions of a shear rate of 9,000 to 41,000 / second and a shearing frequency of 300 to 10,000.

Further, if the polishing pad formed in the slicing step is within the range of ± 3% of the difference in the average value of the diameters of the holes formed on the respective surfaces and the difference in density, a plurality of polishings are performed. Since the average value of the hole diameters is equal in the pad and the proportion of the space occupied by the foam is equal, the variation in the polishing performance can be suppressed. Further, if the average value of the hole diameters of the holes formed on the respective surfaces of the polishing pad is 30 μm to 200 μm, the slurry is held in the holes during the polishing process, so that the polishing efficiency can be improved. I can .

According to a second aspect of the present invention, there is provided an isocyanate group-containing compound, a dispersion obtained by previously dispersing and diluting water in a proportion of 1% by weight to 6% by weight in a polyol compound, a polyamine compound, the isocyanate group-containing compound, A temperature obtained by slicing a foam formed from a mixed liquid obtained by mixing a dispersion and a gas that is non-reactive with the polyamine compound, and the hardness with respect to hardness when immersed in water at a temperature of 20 ° C. for a certain period of time. A polishing pad characterized by having a hardness ratio of 80% or more when immersed in water at 70 ° C. for a predetermined time .

In the second embodiment, the polyol compound may be polypropylene glycol. Moreover, an opening is formed in the surface by the slice of a foam, and it is good also considering the average value of the hole diameter of an opening as 30 micrometers-200 micrometers .

According to the present invention, in the liquid mixture preparation step, the isocyanate group-containing compound, the dispersion liquid obtained by dispersing and diluting water in advance in the polyol compound, and the polyamine compound are mixed, and the gas is blown to prepare the liquid mixture. Fine bubbles are generated by the gas, and the water in the dispersion liquid that has been pre-dispersed and diluted is dispersed almost evenly in the liquid mixture, so that foam is formed that is controlled in size and is evenly dispersed inside the foam. Therefore, by slicing in the slicing step, it is possible to obtain a plurality of polishing pads in which substantially uniform openings are formed substantially uniformly on the surface, and the polishing performance by each polishing pad is suppressed. it is possible, polishing pad was obtained, with respect to the hardness when either a predetermined time immersed in a temperature 20 ° C. water, the same constant water temperature 70 ° C. The proportion of the hardness of 80% or more upon during immersion, the hardness in the wet state even if heating by friction during polishing using a slurry is hard to change, it is possible to suppress a decrease in polishing performance The effect that 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 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 during polishing. The polishing pad 1 includes an isocyanate group-containing compound, a dispersion obtained by previously dispersing and diluting water in a polyol compound, a polyamine compound, and an isocyanate group-containing compound, a gas that is non-reactive with respect to the dispersion and the polyamine compound. It is formed by slicing a foamed product that has been mixed and poured into a mold and cured. That is, the polishing pad 1 is formed by dry molding.

  Inside the polishing pad 1, the foam 3 having a substantially circular cross section is substantially uniformly dispersed by water added at the time of dry molding and a gas that is non-reactive with the isocyanate group-containing compound, the dispersion, and the polyamine compound. Is formed. Since the polishing pad 1 is formed of a slice of foam, a part of the foam 3 is opened on the polishing surface P, and an opening 4 is formed. The opening 4 formed in the polishing surface P has an average opening diameter adjusted to a range of 30 to 200 μm. 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 dispersion prepared by dispersing and diluting water in a polyol compound, and a polyamine compound, an isocyanate group-containing compound, a dispersion, a polyamine compound, and an isocyanate group Mixing process (mixed liquid preparation step) in which a non-reactive gas is mixed with the compound, dispersion and polyamine compound to prepare a mixed liquid, casting process for casting the mixed liquid into a mold, and in the mold And a curing molding step (foam forming step) for foaming and curing to form a foam, a slicing step (slicing step) for slicing the foam into a sheet to form a plurality of polishing pads 1, Manufactured through a laminating process for attaching a double-sided tape. Hereinafter, it demonstrates in order of a process.

(Preparation process)
In the preparation step, an isocyanate group-containing compound, a dispersion obtained by dispersing and diluting water in a polyol compound, 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 foam 3 formed in the foam obtained by producing the mixed spots is varied. On the other hand, if the viscosity is too low, the bubbles move in the mixed solution, and it becomes difficult to form the foam 3 that is substantially uniformly dispersed in the obtained foam. For this reason, it is preferable that a prepolymer sets the viscosity in the temperature of 50 to 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 polyol compound used for preparing the dispersion 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, polytetramethylene glycol, polyethylene glycol, Any high molecular weight polyol compound such as polypropylene glycol can be used. Since it becomes easy to disperse water uniformly in the mixing step by setting the viscosity to the same level as that of the prepolymer or polyamine solution, it is preferable to use a polyol compound having a number average molecular weight of 500 to 2000, and in particular, a number average molecular weight of 1000 to 2000. Polypropylene glycol 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 water is dispersed and diluted at a ratio of 1 to 6% by weight to prepare a dispersion. At the time of preparing the dispersion, stirring and mixing may be performed using a general stirring device, and water may be dispersed and diluted substantially evenly. Although there is no restriction | limiting in particular as water to be used, In order to avoid mixing of an impurity etc., it is preferable to use distilled water. Moreover, it is preferable to prepare the quantity of a dispersion liquid so that the quantity of water may become the ratio of 1-6g with respect to 1 kg of the weight of the prepolymer mixed by the mixing process of the following process. If the amount of water is too small, the size of the foam formed in the resulting foam will be too small. Conversely, if the amount is too large, extremely large foam will be formed. For example, when the weight of the prepolymer is 1 kg and the dispersion is 100 g, the amount of water contained in this dispersion is 1 to 6 g.

  As the polyamine compound, an aliphatic or aromatic polyamine compound can be used, but 3,3′-dichloro-4,4′-diaminodiphenylmethane (hereinafter abbreviated as MOCA) is preferably used. . MOCA is used in a state where it is heated to about 120 ° C. and melted.

(Mixing process, casting process, curing molding process)
As shown in FIG. 2, in the mixing step, the prepolymer, dispersion, and polyamine compound prepared in the preparation step are mixed, and at the same time, a nonreactive gas (hereinafter referred to as nonreactive gas) with respect to the prepolymer, dispersion, and polyamine compound. 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 molded by foaming and curing in the mold. In this example, a mixing process, a casting process, and a curing molding process are performed continuously.

  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. In this example, the size of the mold 25 is set to 1050 mm (length) × 1050 mm (width) × 50 mm (thickness).

  Many of the polyamine compounds represented by the prepolymer of the first component and the MOCA of the second component are both solid or difficult to flow at room temperature, so each supply tank is heated so that each component can flow. ing. 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 this bubble exerts a bubbling effect that disperses the dispersion obtained by dispersing and diluting water substantially uniformly in the mixture. . If the supply amount of the non-reactive gas is too small, the bubbling effect is insufficient and the water dispersion tends to be biased. On the other hand, if the amount is too large, extremely large bubbles are generated. For this reason, it is preferable to adjust the supply amount of a non-reactive gas so that it may become a ratio of 0.5-3.4L with respect to 1 kg of total weight of a prepolymer, a dispersion liquid, and a polyamine compound. 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 to the mixing tank 12, and the non-reactive gas is supplied at a stage where they are 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. When the shear rate of the stirring blade 14 is too low, the size of the foam 3 formed in the resulting foam becomes too large. 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. Variation in the dispersed state of the foam 3 formed on the body is likely to occur. On the other hand, if the number of times of shearing is too small, the size of the generated bubbles is likely to be uneven (variation). On the other hand, if the number of shearing is too large, the viscosity decreases due to temperature rise and the foam 3 is not formed substantially evenly. 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. Simultaneously with the progress of the crosslinking and curing, the isocyanate groups of the prepolymer react with the water dispersed and diluted in the dispersion to generate carbon dioxide. Since the cross-linking and curing proceeds, the generated carbon dioxide does not escape to the outside, and the foam 3 is formed together with the non-reactive gas. In addition, the foam 3 is formed in various shapes such as a circular shape and an elliptical shape in cross section.

(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 foam 3 is substantially uniformly formed is obtained in the curing molding process, the average value of the diameters of the openings 4 formed on the surface of the plurality of polishing pads 1 formed in the slicing process is All are in the range of 30 to 200 μm. Moreover, in each polishing pad 1, the difference of the average value of the hole diameter of the opening 4 is in the range of ± 3%, and the difference of the density is in the range of ± 3%. If the average value of the hole diameters of the open holes 4 is less than 30 μm, the abrasive is likely to be clogged during the polishing process, so that the life of the polishing pad is likely to be shortened. It becomes difficult. The average value of the pore diameters is more preferably in the range of 50 to 180 μm, and particularly in the range of 100 to 170 μm in the polishing of the glass substrate.

(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 the present embodiment, in the mixing step, a prepolymer, a dispersion obtained by dispersing and diluting water in advance in 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. For this reason, fine bubbles are generated by the blown non-reactive gas, and the water in the dispersion previously dispersed and diluted by the bubbles is dispersed substantially uniformly in the mixed solution. In other words, the polyol compound in the dispersion serves to facilitate the dispersion of water in the mixture. Since water is dispersed and diluted in advance in the polyol compound and the dispersion is dispersed in the mixture with bubbles generated by the nonreactive gas, the dispersion state of water in the mixture can be equalized. As a result, carbon dioxide generated by the reaction of water and the isocyanate group of the prepolymer is also dispersed substantially uniformly, so that foam 3 is controlled in size and dispersed evenly inside the resulting foam. Can do. Therefore, by slicing in the slicing step, it is possible to obtain a plurality of polishing pads 1 in which substantially uniform apertures 4 are formed substantially uniformly on the surface. In each of the plurality of polishing pads 1, since slurry is held in the opening 4 during polishing and the slurry is supplied to the surface to be polished, variations in polishing performance can be suppressed.

  Moreover, in this embodiment, a part of polyol compound put into the dispersion liquid for the purpose of improving the dispersibility of water in the mixed liquid forms an isocyanate group-containing compound and a urethane bond. 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 foam formed by the water and the non-reactive gas dispersed substantially uniformly in the mixed solution is re-agglomerated. The curing reaction proceeds before becoming non-uniform. For this reason, the foam 3 can be formed by dispersing the foam 3 substantially uniformly within the obtained foam.

  Furthermore, in this embodiment, since the amount of water dispersed in the mixed liquid is limited by setting the amount of water in the dispersion to a ratio of 1 to 6 g with respect to 1 kg of the weight of the prepolymer, it is large. Foam formation and bias can be suppressed. Thereby, in the plurality of sliced polishing pads 1, the average value of the hole diameters of the openings 4 can be in the range of 30 to 200 μm. Therefore, the polishing scraps are accommodated in the apertures 4 while the slurry is held in the apertures 4 during the polishing process, so that the polishing efficiency can be improved. Moreover, 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 L with respect to 1 kg of the total weight of the prepolymer, the dispersion, and the polyamine compound. Since the amount of the non-reactive gas is limited, it is possible to suppress the formation of extremely large foam inside the obtained foam and to form the substantially uniform foam 3. Furthermore, by setting the viscosity of the prepolymer at a temperature of 50 ° C. 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 step occurs almost uniformly, and the water in the mixed solution Can be equalized. Thereby, the dispersion | distribution of the foaming 3 inside the foam obtained can be suppressed, and a dispersed state can be equalized. Moreover, since the water in a dispersion liquid is disperse | distributed substantially equally by setting a shear rate and the frequency | count of shearing to the conditions mentioned above by the mixing process, the dispersion state of the foam 3 can be equalized.

  Furthermore, a dispersion in which water is dispersed in a polyol compound in advance in the preparation step is prepared, and a foam in which the foam 3 is formed substantially uniformly is obtained by supplying air in the mixing step. In the plurality of polishing pads 1 formed by the above, the difference between the average values of the diameters of the openings 4 formed on the respective surfaces and the difference in the (apparent) density are both within ± 3%. Can do. When the variation in the hole diameter becomes large, abrasive grains (polishing particles), polishing debris, etc. in the slurry are accumulated in the openings 4 during polishing, and local clogging is likely to occur, and the flatness of the object to be polished. Reduce. 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 diameter of the opening 4 of each polishing pad 1 becomes equal, local clogging can be suppressed. In addition, since the proportion of the space occupied by the foam in each polishing pad 1 is equal and the hardness is also equal, it is possible to suppress variation in polishing performance.

  In addition, the polyol compound blended in the dispersion plays a role of facilitating the dispersion of water in the mixed solution, but since it exists in the mixed solution, the hydroxyl group of the polyol compound reacts with the isocyanate group of the prepolymer. By forming a urethane bond, it also serves to make it difficult for the foam to change in hardness 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.

  As described above, since the polishing pad 1 is formed by slicing a foam formed by equalizing the dispersion state of the foam 3, the polishing efficiency can be improved, and the thermal stability (wet hardness retention rate) can be improved. In addition, it is difficult to clog, and the life can be improved. For this reason, it can respond easily to the request | requirement of enlargement (area, thickness) by enlarging the magnitude | size of the foam (making the formwork 25 large).

  In the present embodiment, an isocyanate-terminated urethane prepolymer obtained by reacting a polyol compound and a diisocyanate compound is exemplified as the prepolymer, but the present invention is not limited to this. For example, an active hydrogen compound having a hydroxyl group, an amino group or the like may be used instead of the polyol compound, and a polyisocyanate compound or a derivative thereof may be used instead of the diisocyanate compound, and these may be reacted. In addition, since various kinds of isocyanate-terminated prepolymers are commercially available, commercially available products can be used. Moreover, in this embodiment, although the example which prepares the dispersion liquid which disperse-diluted water in the polyol compound was shown, this invention is not limited to this, For example, a dispersion liquid other than a polyol compound and water, You may make it contain components, such as an additive required in the case of hardening molding.

  Although not particularly mentioned in the present embodiment, the polishing surface P of the polishing pad 1 may be grooved in consideration of the supply of slurry and the discharge of polishing debris. The shape of the groove may be any of a radial shape, a lattice shape, and a spiral shape, and the cross-sectional shape may be any of a rectangular shape, a U shape, a V shape, and a semicircular shape. The pitch, width, and depth of the grooves are not particularly limited as long as the polishing waste can be discharged and the slurry can be moved. When grooving is performed on the polishing pad, for example, if an opening having a large hole diameter is formed on the surface of the polishing pad, the opening and the groove overlap to form a protrusion-like corner, and therefore, the polishing pad is covered during polishing. Scratches will occur in the polished material. In the present embodiment, since the opening 4 of the polishing pad 1 is substantially uniform in the range of the average diameter of 30 to 200 μm, it is possible to suppress the generation of scratches on the object to be polished even when the groove is processed.

  Furthermore, in this embodiment, although the example which uses the mixer 20 in a mixing process and a slicing machine in a slicing process was shown, there is no restriction | limiting in particular in a mixer or a slicing machine, and the mixer and slicing machine which are normally used are used. 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.

  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. . The second component MOCA was dissolved at 120 ° C. and degassed under reduced pressure. The third component dispersion is composed of 50 parts of polypropylene glycol having a number average molecular weight of about 2000, 2 parts of water, 1 part of a catalyst (Toyocat ET, manufactured by Tosoh Corporation), a silicon surfactant (SH-193). And 5 parts of Dow Corning) were added and mixed with stirring, followed by defoaming under reduced pressure. 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 produced in the same manner as in Example 1 except that water was mixed as it was in the mixing step (without being dispersed and diluted in polypropylene glycol) and air was not supplied. In Comparative Example 2, a polishing pad was produced in the same manner as in Example 1 except that water was not mixed and air was supplied and mixed.

(Evaluation)
About the Example and the comparative example, the density and opening diameter of the polishing pad 1 obtained by slicing from the upper layer part, the center part, and the lower layer part of the cured foam 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 diameter of the aperture was observed by magnifying the range of about 1.3 mm square by 175 times with a microscope (manufactured by KEYENCE, VH-6300), 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. Moreover, the ease of slicing in the slicing process was evaluated as slicing properties. The evaluation was made into two stages, that is, ◯: a piece that could be uniformly sliced, and x: a piece that could not be sliced uniformly. The results of density and average pore diameter are shown in Table 1 below, and the results of wet hardness, hardness retention and slicing properties are shown in Table 2 below.

  As shown in Table 1, in Comparative Example 2 in which foaming was formed only with air, foaming with water was not formed, so foaming was reduced and density was increased. Moreover, in Comparative Example 1 in which foaming was formed only with water and Comparative Example 2 in which foaming was formed only with air, the density and average pore diameter were increased in the upper layer portion, the center portion, and the lower layer portion of the obtained foam. Since there is variation, it is considered that there is a bias in the dispersed state of foaming. In particular, in Comparative Example 1, since the bubbling effect by air was not obtained, the stirring spots in the mixing step became large, and both the density and the average pore diameter were greatly varied, resulting in a non-uniform foam. On the other hand, in Example 1 in which foam 3 was formed by preparing a dispersion in which water was previously dispersed in polypropylene glycol and simultaneously supplying air during mixing, in the upper layer part, the central part, and the lower layer part, It was found that both the density and the average pore diameter were substantially uniform (within ± 3%).

  As shown in Table 2, in Comparative Example 1 in which stirring spots were generated, the wet hardness was greatly reduced at a temperature of 70 ° C., and the hardness retention was 67.5%. On the other hand, in Example 1, the hardness retention is 80% or more. From this, in the polishing pad 1 of Example 1, since the hardness change which arises during a grinding | polishing process is suppressed, it can be anticipated that the variation in polishing performance is suppressed. Also in Comparative Example 2, as in Example 1, the hardness retention rate could be maintained at 80% or more. However, since the foam of Comparative Example 2 was not foamed by water, the density and hardness were high. For this reason, slicing in the slicing process becomes very difficult, and a polishing pad having a flat surface cannot be obtained.

  From the above results, the prepolymer, a dispersion obtained by dispersing and diluting water in advance in polypropylene glycol, and MOCA are mixed, and the mixture is blown into air to prepare a mixed solution. It has been found that by dispersing dispersed foam and slicing the obtained foam, it is possible to obtain a polishing pad having substantially uniform openings formed on the surface thereof. Therefore, it has been clarified that variation in polishing performance can be suppressed by polishing using a plurality of polishing pads obtained from one foam.

  The present invention provides a polishing pad manufacturing method in which apertures are formed substantially uniformly and substantially uniformly, and variation between polishing pads is suppressed, and a polishing pad obtained by the manufacturing method. Therefore, it has industrial applicability.

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 3 Foaming 4 Opening hole P Polishing surface 20 Mixer

Claims (12)

A method for producing a polishing pad comprising an isocyanate group-containing compound as a main component,
A preparation step of preparing an isocyanate group-containing compound, a dispersion obtained by previously dispersing and diluting water in a proportion of 1% by weight to 6% by weight in a polyol compound, and a polyamine compound;
Mixing the isocyanate group-containing compound, the dispersion and the polyamine compound, and preparing a mixed liquid by blowing a gas non-reactive with the isocyanate group-containing compound, the dispersion and the polyamine compound; and
Forming a foam from the mixed solution; and
Slicing the foam to form a plurality of polishing pads;
Only including,
The polishing pad formed in the slicing step has a hardness ratio of 80% or more when immersed in water at a temperature of 70 ° C. for a certain time with respect to the hardness when immersed in water at a temperature of 20 ° C. for a certain time. The manufacturing method characterized by the above-mentioned .   The manufacturing method according to claim 1, wherein the mixed solution preparing step and the foam forming step are continuously performed.   2. The production method according to claim 1, wherein the amount of water to be dispersed and diluted in the dispersion liquid in the preparation step is a ratio of 1 g to 6 g with respect to 1 kg of the weight of the isocyanate group-containing compound.   The amount of gas blown into the mixed solution in the mixed solution preparing step is a ratio of 0.5 L to 3.4 L with respect to 1 kg of the total weight of the isocyanate group-containing compound, the dispersion and the polyamine compound. The manufacturing method according to claim 1.   The production method according to claim 1, wherein the polyol compound is polypropylene glycol.   2. The method 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.   The manufacturing method according to claim 1, wherein, in the mixed solution preparing step, the mixed solution is prepared under conditions of a shear rate of 9,000 to 41,000 / second and a shearing frequency of 300 to 10,000.   The polishing pad formed in the slicing step is characterized in that the difference in the average value of the diameters of the openings formed in the respective surfaces and the difference in density are both within a range of ± 3%. Item 2. The manufacturing method according to Item 1.   2. The manufacturing method according to claim 1, wherein the polishing pad formed in the slicing step has an average value of the diameters of the openings formed on the respective surfaces of 30 μm to 200 μm. An isocyanate group-containing compound, a dispersion obtained by dispersing and diluting water in a polyol compound at a ratio of 1% by weight to 6% by weight, a polyamine compound, the isocyanate group-containing compound, the dispersion, and the polyamine compound. It is obtained by slicing a foam formed from a mixed liquid obtained by mixing non-reactive gas, and immersed in water at a temperature of 70 ° C. for a certain period of time when immersed in water at a temperature of 20 ° C. for a predetermined time. A polishing pad, wherein the hardness ratio is 80% or more . The polishing pad according to claim 10 , wherein the polyol compound is polypropylene glycol. 11. The polishing pad according to claim 10 , wherein an opening is formed on a surface by slicing the foam, and an average value of a diameter of the opening is 30 μm to 200 μm.

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