JP5460964B2 - Polishing pad for finishing and method of manufacturing polishing pad for finishing - Google Patents

Description

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

  In materials (objects to be polished) such as semiconductor devices and glass substrates for liquid crystal displays, surface flatness is required, and therefore polishing using a polishing pad is performed. In semiconductor devices, as the degree of integration of semiconductor circuits increases, 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. For this reason, in polishing processing of a semiconductor device or the like, after polishing processing (primary polishing), finishing polishing processing (finish polishing) is further performed.

  Usually, a suede-like soft plastic sheet formed by a wet film forming method is used as a polishing pad for finish polishing. In the wet film-forming method, a resin solution in which a soft plastic (resin) is dissolved in a water-miscible organic solvent is applied to a sheet-shaped film-forming substrate, and then immersed in an aqueous coagulating liquid to form a resin in a sheet form. Coagulated and regenerated. The obtained soft plastic sheet has a surface layer in which micropores are formed on the polishing surface side for polishing an object to be polished, and foam is continuously formed on the inner side of the surface layer. Since foaming is formed with solvent replacement, it is formed in a substantially tear-like shape (substantially triangular pyramid shape) that expands from the polishing surface side toward the inside of the soft plastic sheet. For this reason, since the hole diameter of the opening formed in the polishing surface increases as the polishing pad wears during polishing, the polishing performance such as the polishing rate changes depending on the degree of wear. Moreover, since foaming is formed continuously, dripping occurs when repeatedly used for polishing.

  On the other hand, as the polishing pad for primary polishing, hard foamed polyurethane molded by a dry method is used. In the dry method, usually, a prepolymer containing an isocyanate group-containing compound is cured by a reaction with a curing agent having active hydrogen such as a polyamine compound or a polyol compound to form a foam. The obtained foam is sliced into a sheet to form a polishing pad. Since foam is formed inside the foam during the curing, an opening that can hold the slurry during polishing is formed on the polishing surface of the polishing pad formed by slicing. In the polishing pad by the dry method, foaming is formed independently, so that it is difficult to cause sag compared to the polishing pad by the wet film forming method. However, with a dry polishing pad, it is difficult to equalize and equalize the foam size and dispersion state, and the polishing performance tends to vary. As a technique for equalizing the dispersed state of foaming, a technique in which a silicone compound is added and molded is disclosed (for example, see Patent Document 1).

JP-A-2005-120253

  However, the conventional dry polishing pad is too hard and is not suitable for finish polishing. Even in the dry method, softening can be achieved by using only a polyol compound without using a polyamine compound as a curing agent, but in this case, the pot life becomes long (it takes time to cure). Even in the technique of Patent Document 1, the dispersed state of foaming becomes uneven. In addition, when the opening of the polished surface is clogged by repeating the polishing process, the polished surface is roughened by the dressing process, but since the polyurethane has a viscosity due to softening, a new one can be obtained by the dressing process. It becomes difficult to expose the polished surface. In other words, in the polishing pad softened by the dry method, foaming becomes uneven and it becomes difficult to obtain a stable polishing performance, and the dressing process is difficult to be applied and the life is shortened. Therefore, if the softening can be achieved while maintaining the uniformity of the dispersed state of closed foam, which is an advantage of the dry method, a polishing pad useful for finish polishing can be obtained.

  An object of the present invention is to provide a polishing pad for finishing and a method for manufacturing the polishing pad, in which the dispersion state of foam is equalized and softened while dressing properties are improved in view of the above-mentioned cases.

In order to solve the above-mentioned problem, according to the first aspect of the present invention, water is dispersed and diluted at a ratio of 0.2 wt% to 2.0 wt% in a polyol compound containing an isocyanate group-containing compound and a triol compound. A polyurethane foam formed by dry molding from a mixed liquid obtained by mixing a dispersion and an aromatic tertiary amine compound, and the polyurethane foam is a shore when immersed in water at a temperature of 20 ° C. for a certain period of time. A polishing pad for finishing, wherein the A hardness is in the range of 10 to 60 degrees.

In the first aspect, since the reaction between the isocyanate group-containing compound and the polyol compound is promoted by the catalytic function of the aromatic tertiary amine compound mixed in the mixed solution, the reaction is caused by water dispersed and diluted in the dispersion. It is possible to equalize the dispersion state of the foam in the polyurethane foam by suppressing the unevenness of the bubbles, and since the polyol compound in the dispersion contains a triol compound, a polyamine compound is not used as a curing agent. Since the body is restrained from increasing in hardness and imparts self-disintegration, it is possible to improve the dressing processability while softening the Shore A hardness within a range of 10 to 60 degrees when immersed in water at a temperature of 20 ° C. for a certain period of time. it can.

  In the first embodiment, the aromatic tertiary amine compound may be a pyridine-based tertiary amine compound. At this time, the pyridine-based tertiary amine compound can be 4-dimethylaminopyridine. Moreover, a triol compound may be mixed as a polyol compound in an equivalent ratio of 1: 9 to 5: 5 with a diol compound. At this time, the triol compound may be glycerin or triethanolamine. Moreover, it is preferable to make the quantity of water into the ratio of 1g-6g with respect to 1 kg of weight of an isocyanate group containing compound. In addition, 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 solution, so that the unevenness of foaming can be suppressed. it can.

  In the first embodiment, if 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 is 85% or more, the slurry is used. Since the hardness in a wet state hardly changes even if heat is generated due to friction or the like during the polishing process, a decrease in polishing performance can be suppressed. The polyurethane foam has openings formed on the surface by slicing, and if the average opening diameter of the openings is 30 μm to 200 μm, the slurry is held in the openings during the polishing process, so that the polishing efficiency is improved. be able to. In addition, when a plurality of polyurethane sheets are formed from a polyurethane foam by slicing, if the difference in average pore diameter and the difference in density are both within a range of ± 3% in each polyurethane sheet, a plurality of polishings are performed. Since the average hole diameter at the pad is equal and the proportion of the space occupied by foaming is equal, variations in polishing performance can be suppressed.

The second aspect of the present invention comprises an isocyanate group-containing compound, a dispersion obtained by dispersing and diluting water in a proportion of 0.2 wt% to 2.0 wt% in advance in a polyol compound containing a triol compound, A preparation step of preparing each of the tertiary amine compounds, a mixed solution prepared by mixing the isocyanate group-containing compound, the dispersion, and the aromatic tertiary amine compound are prepared, and the polyurethane foam is prepared from the mixed solution. the includes a foam forming step of dry forming, the said foam molded polyurethane foams which are dry molding in step in the range Shore a hardness of 10 to 60 degrees when immersed certain time in water of a temperature 20 ° C. It is a manufacturing method of the polishing pad for finishing characterized by being.

  In the second aspect, an aromatic tertiary amine compound may be mixed with the isocyanate group-containing compound or the dispersion in advance in the foam molding step. In the foam molding step, the polyurethane foam can be continuously continuously subjected to dry molding after preparing the mixed solution. In the foam molding step, it is preferable to prepare a mixed solution under conditions of a shear rate of 9,000 to 41,000 / second and a shearing frequency of 300 to 10,000. You may make it further include the slicing step of slicing the polyurethane foam dry-molded in the foam molding step.

According to the present invention, since the reaction between the isocyanate group-containing compound and the polyol compound is promoted by the catalytic function of the aromatic tertiary amine compound mixed in the mixed solution, the reaction is caused by water dispersed and diluted in the dispersion. It is possible to equalize the dispersion state of the foam in the polyurethane foam by suppressing the unevenness of the bubbles, and since the polyol compound in the dispersion contains a triol compound, a polyamine compound is not used as a curing agent. Since the body is restrained from increasing in hardness and imparts self-disintegration, it is possible to improve the dressing processability while softening the Shore A hardness within a range of 10 to 60 degrees when immersed in water at a temperature of 20 ° C. for a certain period of time. The effect that it is possible can be acquired.

  Hereinafter, embodiments of a polishing pad for finishing to which the present invention is applied will be described with reference to the drawings.

(Polishing pad)
As shown in FIG. 1, the polishing pad 1 has a hard foam type polyurethane sheet 2, and has a polishing surface P that abuts a polishing surface (processing surface) of an object to be polished via a slurry during polishing processing. Have. The polyurethane sheet 2 contains an isocyanate group-containing compound as a main component. The polyurethane sheet 2 is cured by pouring a mixed solution of an isocyanate group-containing compound, a dispersion obtained by dispersing and diluting water into a polyol compound containing a triol compound, and an aromatic tertiary amine compound into a mold. It is formed by slicing the polyurethane foam. That is, the polyurethane sheet 2 is formed by dry molding.

  Inside the polyurethane sheet 2, the foam 3 having a substantially circular cross section is formed substantially uniformly dispersed by water dispersed and diluted in a dispersion. Since the polyurethane sheet 2 is formed by slicing a polyurethane foam, the foam 3 is opened on the polishing surface P, and the 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. In the polyurethane sheet 2 on which such foam 3 is formed, the Shore A hardness is in the range of 10 to 60 degrees. In addition, the polyurethane sheet 2 has a wet hardness retention defined by a ratio of hardness when immersed in water (hot water) at a temperature of 70 ° C. for the same fixed time with respect to hardness when immersed in water at a temperature of 20 ° C. for a certain time. 85% or more.

  In addition, the polishing pad 1 has a double-sided tape for attaching the polishing pad 1 to a polishing machine on the surface opposite to the polishing surface P of the polyurethane sheet 2. The double-sided tape has an adhesive layer (not shown) on both surfaces of a base material 7 such as a polyethylene terephthalate (hereinafter abbreviated as PET) film. Examples of the adhesive for the adhesive layer include acrylic adhesives. The double-sided tape is bonded to the polyurethane sheet 2 with an adhesive layer on one side, and the adhesive layer on the other side is covered with a release paper 8.

(Manufacture of polishing pad)
The polishing pad 1 is manufactured through each process shown in FIG. That is, a preparation step (preparation step) for preparing an isocyanate group-containing compound, a dispersion obtained by dispersing and diluting water in a polyol compound containing a triol compound, and an aromatic tertiary amine compound, an isocyanate group-containing compound, a dispersion Mixing process (part of foam molding step) for mixing liquid and aromatic tertiary amine compound to prepare a mixed liquid, casting process for casting mixed liquid into mold (part of foam molding step) ), A curing molding process (part of the foam molding step) for foaming and curing in a mold to form a polyurethane foam, and a slicing process (slicing) for slicing the polyurethane foam into a sheet to form a polyurethane sheet 2 Step), and is manufactured through a laminating process in which the polyurethane sheet 2 and the double-sided tape are bonded together. Hereinafter, it demonstrates in order of a process.

(Preparation process)
In the preparation step, an isocyanate group-containing compound, a dispersion, and an aromatic tertiary amine 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 polyurethane 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 dispersed substantially uniformly in the obtained polyurethane 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 polyol compound used for the preparation of the dispersion functions as a curing agent for curing the prepolymer, and forms a hard segment (a urethane bond portion that imparts rigidity at a high melting point). The polyol compound is not particularly limited as long as it contains a triol compound. Examples of compounds other than the triol compound include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, and neopentyl glycol. , Pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol and other low molecular weight polyol compounds, and polytetramethylene glycol, polyethylene glycol, polypropylene glycol and other high molecular weight polyol compounds are used. can do. Although there is no restriction | limiting in particular as a triol compound, In order to prevent the hardness of the polyurethane foam obtained from becoming too high, it is preferable to use glycerol or a triethanolamine. Moreover, in order to soften the polyurethane foam, it is preferable to use a triol compound and a diol compound as a polyol compound by mixing them in an equivalent ratio of 1: 9 to 5: 5. As the diol compound, the above-described ethylene glycol or the like can be used, but considering the dispersibility in the mixing step, polypropylene glycol having a number average molecular weight of 300 to 700 (hereinafter abbreviated as PPG) is used. It is preferable. In this example, glycerin and PPG having a number average molecular weight of 300 to 700 were mixed and used as a polyol compound at a ratio of 2: 8.

  In preparing the dispersion, water is dispersed and diluted in a ratio of 0.2 to 2.0% by weight in a mixture of glycerin and PPG. 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. The amount of the dispersion is prepared so that the amount of water is 1 to 6 g with respect to 1 kg of the weight of the prepolymer mixed in the subsequent mixing step. If the amount of water is too small, the number of foams formed in the polyurethane foam will be small. Conversely, if the amount is too large, extremely large foams will be formed.

  The aromatic tertiary amine compound prepared in the preparation step functions as a reaction catalyst for promoting the reaction between the prepolymer and the polyol compound in the dispersion, and shortens the curing time in the curing molding step (shortens the pot life). ) Play a role. The aromatic tertiary amine compound is not particularly limited, but specific examples include 4-dialkylaminopyridine such as 4-dimethylaminopyridine, dimethylbenzylamine, 2-ethylimidazole, 2-ethyl- 4-methylimidazole and the like can be mentioned. In particular, it is preferable to use a pyridine-based tertiary amine compound, and it is more preferable to use 4-dialkylaminopyridine. In this example, 4-dimethylaminopyridine is used as the aromatic tertiary amine compound, and is prepared at a rate of 5 g with respect to 1 kg of the prepolymer weight to be mixed in the subsequent mixing step. In addition, although 4-dimethylaminopyridine used in this example is yellow in a state where it is mixed with the liquid mixture in the mixing step, it becomes white after the reaction at the time of curing and molding sufficiently proceeds. It also serves as an indicator of reaction progress.

(Mixing process, casting process, curing molding process)
As shown in FIG. 2, in the mixing step, the prepolymer prepared in the preparation step, the dispersion, and the aromatic tertiary amine compound are mixed to prepare a mixed solution. In the casting process, the mixed liquid prepared in the mixing process is cast into a mold, and in the curing molding process, the polyurethane 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 polyurethane 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, supply tanks each containing a prepolymer as a first component and a mixed liquid obtained by mixing an aromatic tertiary amine compound in a dispersion as a second component are arranged. The supply port from each supply tank is connected to the upstream end of the mixing tank 12. The stirring blade 14 is fixed to a rotating shaft arranged from the upstream side to the downstream side at a substantially central portion in the mixing tank 12. As the rotating shaft rotates, the stirring blade 14 rotates, and the first component and the second component are sheared and mixed. The obtained liquid mixture is poured into the mold 25 from a discharge port formed at the downstream end of the mixing tank 12. The upper part of the mold 25 is open, and in this example, the size is set to 1050 mm (length) × 1050 mm (width) × 50 mm (thickness).

  Since the prepolymer of the first component, the polyol compound contained in the second component, and the aromatic tertiary amine compound are all solid or difficult to flow at normal temperature, each component can flow in each supply tank. So that it is warmed.

  By adjusting the mixing conditions in the mixer 20, that is, the shearing speed and the number of shearing of the stirring blade 14, the components are mixed almost uniformly to prepare a mixed solution. If the shear rate of the stirring blade 14 is too low, the size of the foam 3 formed in the resulting polyurethane 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 the bubbles in the mixed solution move (during molding), and the polyurethane foam Variation in the dispersed state of the foam 3 formed 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). For this reason, in a mixing process, a shear rate is set to the range of 9,000-41,000 / sec, and the frequency | count of shear is set to the range of 300-10,000 times, and it mixes. The mixing time (residence time) in the mixer 20 is about 1 second although it depends on the flow rate of the mixed liquid (maximum 1 liter / sec). That is, for example, the time required to cast the mixed solution into the mold 25 of about 100 kg in the casting process is about 1 to 2 minutes. In addition, a shear rate and the frequency | count of shear can be calculated | required by following Formula. That is, shear rate (/ sec) = diameter (mm) of blade tip of stirring blade 14 × circularity × rotational speed (rpm) of stirring blade 14 ÷ 60 ÷ blade tip of stirring blade 14 and inner wall of mixing vessel 12 Clearance (mm), number of times of shearing (times) = rotation speed of stirring blade 14 (rpm) ÷ 60 × retention time of mixed solution in mixing tank 12 (second) × number of blades of stirring blade 14 Can do.

  When casting the mixed solution into the mold 25 in the casting step, the mixed solution from the mixer 20 is discharged from the discharge port of the mixing tank 12 and, for example, between two opposing sides of the mold 25 through a flexible pipe. 3 (for example, between the left and right in FIG. 3), the liquid is reciprocated in the length direction, and is introduced into a liquid injection port (not shown) having a triangular cross section having a length in the width direction of the mold 25. The end of the discharge port (the end of the flexible pipe) is reciprocated in the width direction of the mold 25 while the liquid injection port is reciprocated in the length direction of the mold 25. The liquid mixture is cast into the mold 25 substantially evenly.

  In the curing molding process, the cast liquid mixture is reacted and cured in the mold 25 to mold the polyurethane foam. At this time, the prepolymer is crosslinked and cured by reaction with the polyol compound. Since the upper part of the mold 25 is open, the crosslinking and curing proceeds under atmospheric pressure, and a polyurethane foam is molded. Simultaneously with the progress of the crosslinking and curing, water dispersed and diluted in the dispersion reacts with the isocyanate group of the prepolymer, thereby generating carbon dioxide. Since the cross-linking and curing proceeds, the generated carbon dioxide does not escape to the outside and forms the foam 3. 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 polyurethane foam obtained in the curing molding step is sliced into a sheet to form the polyurethane sheet 2. A general slicing machine can be used for slicing. At the time of slicing, the lower layer portion of the polyurethane 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. In addition, in the polyurethane 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 polyurethane foam is not used due to scratches, etc. 10 to 25 polyurethane sheets 2 can be formed from about 30 mm. Since the polyurethane foam in which the foam 3 is substantially uniformly formed is obtained in the curing molding process, when a plurality of polyurethane sheets 2 are formed in the slicing process, the average aperture diameter of the apertures 4 formed on the surface Are in the range of 30 to 200 μm. Moreover, in each polyurethane sheet 2, the difference of the average hole diameter of the opening 4 is in a range of ± 3% with respect to the average value, and the difference in density is in a range of ± 3% with respect to the average value. If the average aperture diameter of the apertures 4 is less than 30 μm, the abrasive is likely to be clogged at the time of polishing, so that the life of the polishing pad is likely to be shortened. Conversely, if it exceeds 200 μm, it is difficult to control the substantially uniform aperture diameter. Become. The average pore diameter is more preferably in the range of 40 to 180 μm. In addition, the magnitude | size of the foam 3 and by extension, the hole diameter of the opening 4 can be controlled by adjusting the quantity and mixing conditions of the water mixed with a liquid mixture.

(Lamination process)
In the laminating process, the polyurethane sheet 2 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 adhesion of dirt or foreign matter is performed to complete the polishing pad 1.

  When polishing an object to be polished, the polishing pad 1 is mounted on a polishing surface plate of a polishing machine. When the polishing pad 1 is mounted on the polishing surface plate, the release paper 8 is removed, and the surface is adhered and fixed to the polishing surface plate with the exposed adhesive layer. The processing surface (surface to be polished) of the object to be polished is polished by pressurizing the object to be polished and rotating the polishing surface plate while supplying the 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, a polyol compound containing a triol compound is used for the dispersion liquid to be mixed in the mixing step. Since the polyol compound has active hydrogen in the molecule, it functions as a curing agent by reacting with the prepolymer. When an amine compound is used as the curing agent having active hydrogen, a urea bond is formed in the polyurethane resin formed by the reaction with the prepolymer. Since this urea bond is easier to form a hydrogen bond than a urethane bond, the hardness of the polyurethane resin is increased. On the other hand, when a polyol compound is used, since a urea bond is not formed but only a polyurethane bond is formed, the formation of hydrogen bonds is reduced and the hardness of the polyurethane resin is lowered. Therefore, the polyurethane foam obtained, and by extension, the polyurethane sheet 2 obtained by slicing the polyurethane foam can be softened by the reduction in the formation of hydrogen bonds.

  Moreover, since a polyol compound contains a triol compound, a branch is formed in the main chain of the polyurethane resin constituting the polyurethane foam formed by the reaction with the prepolymer. For this reason, since the intermolecular force of the polyurethane resin is limited, the viscosity of the polyurethane resin can be reduced and self-disintegrating property can be imparted even if the polyurethane resin is softened. If the polyurethane resin is viscous, for example, when the dressing process is performed in order to eliminate clogging caused by polishing, the polyurethane resin is stretched and is not easily cut, and the dressing process becomes insufficient. On the other hand, in the polyurethane sheet 2 of this embodiment, since self-disintegrating property is provided, the dressing property can be improved while being softened. Therefore, even if clogging of the opening 4 occurs during polishing, the dressing process can be performed to expose the new polishing surface P and regenerate the opening 4, so that the life of the polishing pad 1 can be improved. it can.

  Furthermore, when a polyol compound is used as the curing agent, the polyurethane sheet 2 can be softened as described above, but on the other hand, the reaction with the prepolymer is delayed and the curing time is prolonged (pot life is prolonged). . For this reason, bubbles generated in the mixing step move during the curing of the polyurethane resin in the curing molding step, and the dispersed state of the foam 3 becomes uneven in the obtained polyurethane foam. In this embodiment, an aromatic tertiary amine compound is mixed in the liquid mixture prepared in the mixing step. Since the aromatic tertiary amine compound does not have an active group in the molecule, it does not react with the prepolymer or the polyol compound, and functions as a reaction catalyst between the prepolymer and the polyol compound. For this reason, reaction of a prepolymer and a polyol compound is accelerated | stimulated and a pot life is shortened, Therefore The movement of the bubble in a hardening molding process can be suppressed. Thereby, since the dispersion state of the foam 3 in the polyurethane foam is equalized, the openings 4 are formed substantially uniformly on the polishing surface P in the polyurethane sheet 2 obtained by slicing. Accordingly, the polishing pad 1 can be prevented from sag even if the polishing process is repeated, and the opening diameter of the opening 4 does not change greatly even when the polyurethane sheet 2 is worn. Etc. can be maintained.

  Furthermore, in this embodiment, the amount of water mixed in the mixed liquid is set to a ratio of 1 to 6 g with respect to 1 kg of the weight of the prepolymer. The water in the mixed solution reacts with the isocyanate group of the prepolymer to generate carbon dioxide and foam is formed. However, since the amount of water relative to the prepolymer is limited, the polyurethane foam obtained in the curing molding process is foamed 3 Can be formed to be distributed substantially evenly. Since the polyurethane sheet 2 is formed by slicing a polyurethane foam in which the foam 3 is formed, the size of the polyurethane foam is increased (area and thickness) by increasing the size of the polyurethane foam (enlarging the mold 25). It is possible to easily respond to the request.

  Furthermore, in this embodiment, water is mixed with the liquid mixture as a dispersion liquid in which the polyol compound is dispersed and diluted in a proportion of 0.2 to 2.0% by weight in advance. For this reason, since the dispersion state of the water in a liquid mixture is equalized, the bias | inclination of the foam 3 formed in the inside of a foam can be suppressed. Thereby, since the foam 3 of the polyurethane sheet 2 is in a substantially uniformly dispersed state, the openings 4 formed in the polishing surface P can be equalized.

  Moreover, in this embodiment, the polyol compound mix | blended with the dispersion liquid reacts with a prepolymer, and forms a urethane bond. As described above, in the case of a urea bond in which a hydrogen bond is more likely to be formed than a urethane bond, the heat resistance is improved in a dry state, but the hydrogen bond is broken in a wet state to reduce the heat resistance. On the other hand, in the polyurethane sheet 2, since a urethane bond is formed, it is possible to suppress a decrease in heat resistance even in a wet state. For this reason, in the polishing pad 1, the wet hardness retention rate, that is, the ratio of the hardness when immersed in 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 85% or more. It can be. Therefore, in the polishing pad 1 having improved thermal stability in a wet state, even if heat is generated due to friction or the like during polishing using a slurry, the change in hardness is suppressed, and the polishing performance can be stabilized.

  Furthermore, in this embodiment, since the polyurethane sheet 2 is obtained by slicing the polyurethane foam in which the foam 3 is substantially uniformly formed, the average aperture diameter of the apertures 4 formed on the polishing surface P is 30 to 200 μm. It is adjusted to the range. For this reason, the slurry is held in the opening 4 during polishing and is stably supplied to the processed surface (surface to be polished) of the object to be polished, so that the polishing efficiency can be improved. Further, when a plurality of polyurethane sheets 2 are formed from a polyurethane foam, the difference in average pore diameter of the apertures 4 formed on the respective surfaces and the difference in (apparent) density are both relative to the average value. Within a range of ± 3%. When the variation in the aperture diameter becomes large, the aperture 4 is likely to be locally clogged by abrasive grains (abrasive particles), polishing debris, etc. in the slurry during polishing, and the flatness of the object to be polished is lowered. Further, since the hardness becomes too small (soft) when the density is reduced, it is difficult to improve the flatness of the object to be polished. On the contrary, if the density is increased, the hardness becomes too high, so that the polishing efficiency is lowered and the object to be polished is easily damaged. In the present embodiment, since the average opening diameter of the openings 4 is equal between the plurality of polishing pads 1, local clogging can be suppressed. Further, since the proportion of the space occupied by the foam 3 in each polishing pad 1 is equal and the hardness is also equal, even if the polishing pad 1 is replaced, it is possible to suppress the occurrence of variations in the polishing performance.

  Furthermore, the viscosity of the prepolymer at a temperature of 50 to 80 ° C. is set in a range of 500 to 4000 mPa · s. For this reason, since the movement of foaming is suppressed in the mixed solution, the unevenness of foaming can be suppressed and the foaming can be dispersed substantially uniformly. Further, in the mixing step, the mixture is prepared under conditions of a shear rate of 9,000 to 41,000 / second and a shearing frequency of 300 to 10,000. For this reason, since water is disperse | distributed substantially equally, the dispersion | distribution state of the foam 3 can be equalized.

  As described above, in the polishing pad 1 of the present embodiment, the independent foam, which is a feature of the dry method, is formed substantially uniformly inside the polyurethane sheet 2 and softening is achieved. For this reason, even if the polyurethane sheet 2 is worn by the polishing process, the polishing performance such as the polishing rate can be stably exhibited, and the polyurethane sheet 2 can be prevented from being sag. Moreover, the dressing property is improved by providing the polyurethane sheet 2 with a self-disintegrating property. The polishing pad 1 using such a polyurethane sheet 2 is extremely useful as a polishing pad for finishing a semiconductor device or the like.

  Conventionally, polishing pads using a suede-like soft plastic sheet formed by a wet film forming method are used in finish polishing of semiconductor devices and the like. In the polishing pad by the wet film forming method, the foam formed inside with the solvent substitution has a substantially tear-like shape, so that the opening diameter of the polishing surface increases and the polishing performance changes with wear during polishing. In addition, since foaming is continuously formed, sag is likely to occur when repeatedly used for polishing. On the other hand, in the polishing pad using the hard foam polyurethane molded by the dry method, foaming is formed independently, so that it is less likely to sag compared to the polishing pad by the wet film formation method, It is difficult to make the sheath dispersion state uniform and uniform, and the polishing performance tends to vary. Further, since the hardness is too high in the dry method, scratches on the object to be polished are caused in finish polishing. Softening can also be achieved by a dry method, but in this case, the pot life becomes long, so that the dispersed state of foam becomes uneven and it becomes difficult to obtain stable polishing performance. Further, since the polyurethane has viscosity due to softening, the dressing process is difficult to be applied and the life is shortened. The polishing pad 1 of this embodiment can solve these problems.

  In the present embodiment, an example in which the aromatic tertiary amine compound is previously mixed with the dispersion (second component) in the mixing step has been described, but the present invention is not limited to this. For example, in order to make the reaction between the prepolymer and the polyol compound more uniform, an aromatic tertiary amine compound may be mixed in advance with the prepolymer (first component). In the mixing step, the aromatic tertiary amine compound may be mixed alone as the third component.

  Moreover, in this embodiment, although the isocyanate terminal urethane prepolymer which made the polyol compound and the diisocyanate compound react was illustrated as a prepolymer, this invention is not limited to this. For example, an active hydrogen compound having a hydroxyl group, an amino group or the like may be used instead of the polyol compound, and a polyisocyanate compound or a derivative thereof may be used instead of the diisocyanate compound, and these may be reacted. In addition, since various kinds of isocyanate-terminated prepolymers are commercially available, commercially available products can be used.

  Furthermore, in the present embodiment, an example of preparing a dispersion in which water is 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 water, for example, In addition, components such as additives necessary for curing and molding may be included. Furthermore, water may be mixed as it is in the mixing step without preparing a dispersion, but in consideration of reacting water with the isocyanate group of the prepolymer substantially uniformly, dispersion dispersed and diluted in a polyol compound It is preferable to use a liquid.

  Furthermore, in the present embodiment, an example in which the mixing step, the casting step, and the curing molding step are continuously performed is shown, but the present invention is not limited to this, and each step is performed independently. May be. In the present embodiment, an example is shown in which casting is performed from the mixer 20 to the mold 25 and molding is performed under atmospheric pressure, but the present invention is not limited to this. For example, the liquid mixture may be prepared in a container and cured and molded in the container, or the container may be sealed and cured and molded under pressure.

  Although not particularly mentioned in the present embodiment, the polishing surface P of the polishing pad 1 may be subjected to grooving or embossing in consideration of 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. 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.

  Moreover, 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 and a slicing machine, 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 1 produced by changing the mixing amount of the aromatic tertiary amine compound and water according to the present embodiment will be described. A comparative example prepared for comparison is also shown.

Example 1
In Example 1, as shown in Table 1 below, Samples 1 to 7 were prepared as the polishing pads 1 by changing the mixing amount of the aromatic tertiary amine compound and water. A terminal isocyanate group-containing urethane prepolymer (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 dispersion of the second component is a mixture of glycerin, PPG having a number average molecular weight of about 500 and water in the proportions shown in Table 1, and 5 of a silicon surfactant (SH-193, manufactured by Dow Corning). And 4-dimethylaminopyridine as an aromatic tertiary amine compound were added and mixed with stirring, followed by degassing under reduced pressure. The 1st component: 2nd component was supplied to the mixing tank 12 so that it might become the ratio shown in Table 1 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. The obtained mixed liquid was poured into a mold 25 and cured, and then the molded foam was extracted from the mold 25. This foam was sliced to a thickness of 1.3 mm to produce a polyurethane sheet 2. Sample 1 is a sample of a comparative example in which neither an aromatic tertiary amine compound nor water is mixed. Sample 2 is a sample of a comparative example in which an aromatic tertiary amine compound is mixed but water is not mixed. Sample 7 is a comparative sample prepared in the same manner as Sample 4 except that a general catalyst (Toyocat ET, manufactured by Tosoh Corporation) is used instead of the aromatic tertiary amine compound.

  Each sample was evaluated for homogeneity by measuring density and pore diameter, heat resistance by measuring wet hardness and hardness retention rate, and dressing property by measuring dressability. Each measurement item was measured by the following measurement method, and the obtained evaluation results are shown in Table 2 below.

(Evaluation of homogeneity)
In the evaluation of homogeneity, the density and pore diameter of the polyurethane sheet 2 obtained by slicing from the upper layer portion, middle layer portion, and lower layer portion of the cured polyurethane foam were measured, and the homogeneity was determined from the difference in the measured values in each layer. Sex was evaluated. The density was calculated from the volume obtained from the size obtained by measuring the weight of the sample cut into a predetermined size. In addition, the aperture diameter was observed with a microscope (manufactured by KEYENCE, VH-6300) by enlarging the range of about 1.3 mm by 175 times, and the obtained image was image processing software (Image Analyzer V20LAB Ver.1. It processed and calculated by 3).

(Evaluation of heat resistance)
In the evaluation of heat resistance, wet (WET) hardness and hardness retention were measured for the polyurethane sheet 2 obtained from the middle layer of the polyurethane foam. The wet hardness was determined by immersing the polyurethane sheet 2 in water at a temperature of 20 ° C. for 30 minutes, and then measuring the Shore A hardness according to Japanese Industrial Standard (JIS K 7311) as the hardness. The hardness retention is determined by immersing the same polyurethane sheet 2 in hot water at a temperature of 70 ° C. for 30 minutes, measuring the Shore A hardness in the same manner, and determining the percentage of the hardness at 70 ° C. relative to the hardness at 20 ° C. as a percentage. It was.

(Evaluation of dressability)
In the evaluation of dressing property, the surface of the prepared polishing pad 1 is a diamond dresser (manufactured by Asahi Diamond Co., Ltd., M type # 100, 20 cmφ), a dresser load of 117 g / cm ² , a polishing platen rotation speed of 100 rpm, and a dresser rotation speed. Dressing (dressing process) was performed at 75 rpm for 5 minutes. After dressing, the polishing pad 1 was observed with a scanning electron microscope to visually determine the degree of dressing. Judgment was made in three stages: x: difficult to dress (unsatisfactory), ○: dressing was appropriate, and Δ: dressing was too much.

  As shown in Tables 1 and 2, in Sample 1 containing no aromatic tertiary amine compound and water, no foam was formed. Moreover, since only the polyol compound was used as the curing agent, the pot life was prolonged. No foaming was formed even in Sample 2 containing an aromatic tertiary amine compound but not containing water. From this, it was found that if water was not added, the aromatic tertiary amine compound alone did not contribute to foam formation. Further, in sample 7, variations in density and average pore diameter were observed in the upper layer, middle layer, and lower layer. Furthermore, the hardness was too low, and the dressability was lowered. On the other hand, in Sample 3 to Sample 6 to which an aromatic tertiary amine compound and water were added, density and average pore diameter were substantially uniform (within ± 3%) in the upper layer portion, middle layer portion, and lower layer portion. In addition, the wet hardness results showed that the film was softened. In addition, it was found that the dressing property is excellent even when softened and the hardness retention is high, so that it can be expected to improve the polishing characteristics.

  Since the present invention provides a polishing pad for finishing and a method for producing the polishing pad that has improved the dispersibility of foaming while improving the dispersibility of foaming and softening, and contributes to the production and sales of the polishing pad. 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

1 Polishing pad 2 Polyurethane sheet (Polyurethane foam)
3 Foaming 4 Opening P Polishing surface 20 Mixer

Claims (15)

A mixture of an isocyanate group-containing compound, a polyol compound containing a triol compound, a dispersion obtained by dispersing and diluting water at a ratio of 0.2 wt% to 2.0 wt%, and an aromatic tertiary amine compound. A polyurethane foam that is dry-molded from a liquid, and the polyurethane foam has a Shore A hardness in the range of 10 to 60 degrees when immersed in water at a temperature of 20 ° C. for a certain period of time. Polishing pad.   The polishing pad according to claim 1, wherein the aromatic tertiary amine compound is a pyridine-based tertiary amine compound.   The polishing pad according to claim 2, wherein the pyridine-based tertiary amine compound is 4-dimethylaminopyridine.   The polishing pad according to claim 1, wherein the triol compound is mixed with the diol compound in an equivalent ratio of 1: 9 to 5: 5.   The polishing pad according to claim 4, wherein the triol compound is glycerin or triethanolamine.   2. The polishing pad according to claim 1, wherein the amount of water is 1 to 6 g per 1 kg of the isocyanate group-containing compound.   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.   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 a certain time with respect to the hardness when immersed in water at a temperature of 20 ° C. is 85% or more. .   2. The polishing pad according to claim 1, wherein the polyurethane foam has openings formed on the surface by slicing, and an average opening diameter of the openings is 30 μm to 200 μm.   When a plurality of polyurethane sheets are formed from the polyurethane foam by the slicing, each polyurethane sheet has a difference in average pore diameter and a difference in density both within a range of ± 3%. The polishing pad according to claim 9. A dispersion obtained by dispersing and diluting water in a ratio of 0.2 wt% to 2.0 wt% in advance in an isocyanate group-containing compound and a polyol compound containing a triol compound, and an aromatic tertiary amine compound are prepared. Preparation steps,
A foam molding step of preparing a mixed liquid obtained by mixing the isocyanate group-containing compound, the dispersion, and the aromatic tertiary amine compound, and dry-molding a polyurethane foam from the mixed liquid;
Including
The foam molding step by a dry molded polyurethane foam production method of finishing polishing pad, wherein the Shore A hardness when a predetermined time immersed in water at a temperature 20 ° C. in the range of 10 to 60 degrees .   12. The method according to claim 11, wherein in the foam molding step, the aromatic tertiary amine compound is mixed in advance with the isocyanate group-containing compound or the dispersion.   The manufacturing method according to claim 11, wherein, in the foam molding step, the polyurethane foam is continuously subjected to dry molding after preparing the mixed solution.   12. The manufacturing method according to claim 11, wherein in the foam molding 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 manufacturing method according to claim 11, further comprising a slicing step of slicing the polyurethane foam dry-molded in the foam molding step.

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