JP5461133B2 - Polishing cloth - Google Patents

Description

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

  Conventionally, various materials such as semiconductor devices have been polished using a polishing cloth to ensure flatness. In the manufacture of a semiconductor device, a copper (Cu) wiring layer and an insulating layer are usually formed sequentially to be multilayered, and the surface (processed surface) after forming each layer is polished. In recent years, as the degree of integration of semiconductor circuits has increased rapidly, miniaturization and multilayer wiring have been promoted for the purpose of higher density, and a technique for further flattening the processed surface has become important.

  Generally, in the manufacture of semiconductor devices, a chemical mechanical polishing (hereinafter abbreviated as CMP) method is used. In the CMP method, a slurry (polishing liquid) in which abrasive grains (polishing particles) are dispersed in an alkali solution or an acid solution is usually supplied. That is, the object to be polished (the processed surface thereof) is flattened by a mechanical polishing action by the abrasive grains in the slurry and a chemical polishing action by the alkali solution or acid solution.

  In polishing processing of a semiconductor device by the CMP method, a polishing cloth is generally used that is formed by a dry molding method and includes a resin sheet in which an opening is formed on a polishing surface for polishing an object to be polished. At the time of polishing, the processed surface is flattened by being supplied so that the abrasive grains are dispersed in the processed surface while being held in the openings formed in the polished surface. In other words, it is essential that the polishing cloth for a semiconductor device has an opening formed in the polishing surface. Such an opening can be formed by forming a resin foam by a dry molding method and grinding the surface of the obtained foam or slicing the foam. As a technique for forming a foam by a dry molding method, for example, a technique in which hollow fine particles are added to a resin solution at the time of molding is disclosed (Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4). , See Patent Document 5). In addition, a technique for generating gas at the time of molding by adding water to the resin solution (for example, see Patent Document 6), a technique for dispersing an inert gas in the resin solution and molding (for example, see Patent Document 7). Also disclosed is a technique for adding water-soluble fine particles to a resin solution (see, for example, Patent Document 8).

Japanese Patent No. 3013105 Japanese Patent No. 3425894 Japanese Patent No. 3801998 JP 2006-186394 A JP 2007-184638 A JP 2005-68168 A Japanese Patent No. 3455208 JP 2000-34416 A

  However, since the techniques of Patent Documents 1 to 8 are all formed by a dry molding method, the obtained resin sheet is hard and mainly an independent foam type. For this reason, there exists a problem that the opening formed in the grinding | polishing surface becomes clogged with an abrasive grain, grinding | polishing waste, etc., and becomes easy to block | close. When the opening is closed, the abrasive grains and the like are likely to aggregate, and as a result, there is a risk of causing scratches (scratches) on the processed surface of the workpiece. In the polishing process of a semiconductor device, if a scratch is generated, there is a risk of cutting the wiring, which is a fatal defect. If the polishing process is interrupted and the surface is dressed, the holes are regenerated and the polishing process can be continued. However, since the dressing is essential, the polishing efficiency is lowered. Moreover, since a hard resin sheet has insufficient cushioning properties, it needs to be bonded to another sheet having cushioning properties. As described above, with the advancement of flatness required for the processing surface of semiconductor devices, the demand for polishing performance such as polishing accuracy and polishing efficiency by the CMP method is also increasing, and accordingly the hole diameter of the polishing cloth is also finer. There is a growing demand for equalization and uniformity. Furthermore, when aiming at an efficient manufacture by improving a yield, the polishing cloth which can suppress fatal faults, such as a scratch, is anxious.

  An object of the present invention is to provide a polishing cloth capable of suppressing scratches and improving the flatness of an object to be polished in view of the above-mentioned cases.

In order to solve the above-described problems, the present invention provides a polishing cloth including a polishing layer having a polishing surface for polishing an object to be polished, wherein the polishing layer has a columnar shape having elasticity and a uniform height. A large number of resin materials are formed so as to be circumscribed on the side surface, and are formed in a flat shape. Gaps are formed between the resin materials , and the resin material has a polyurethane elasticity having a diameter of 10 μm to 80 μm. It is a thread .

In the present invention, since the height of the resin material is uniform, the thickness of the polishing layer formed by spreading the resin material is made uniform, and the gap is formed between the resin materials so as to penetrate in the thickness direction. A polyurethane elastic yarn in which polishing scraps are easily accommodated and a resin material having a diameter in the range of 10 μm to 80 μm is spread, so that a gap between the resin materials is reduced and a dispersed state of the slurry is equalized, and the resin material has elasticity. Since cushioning properties are exhibited, scratching can be suppressed during polishing and the flatness of the object to be polished can be improved.

In this case, it is preferable that the circumscribed portion of the resin material is fixed. The area ratio of voids formed between the resin materials per unit area of the polishing surface of the polishing layer can be in the range of 9% to 30%. A resin material can be made into the column shape with a uniform diameter. At this time, the height of the resin material may be in the range of 500 μm to 5000 μm. In addition, the polishing layer may be formed by cutting an elastic yarn bundle in which polyurethane elastic yarns are aligned in the longitudinal direction in a direction intersecting the longitudinal direction. In the elastic yarn bundle, adjacent polyurethane elastic yarns are preferably heat-sealed. The polyurethane elastic yarn may be a monofilament or a multifilament in which a plurality of monofilaments are twisted together. At this time, the fineness of the monofilament can be in the range of 1 dtex to 70 dtex. Moreover, the space | gap formed between resin materials may be formed in the uniform dispersion | distribution state by the uniform magnitude | size.

According to the present invention, since the height of the resin material is uniform, the thickness of the polishing layer formed by spreading the resin material is made uniform, and the gap is formed so as to penetrate between the resin materials in the thickness direction. polyurethane having with polishing debris is likely to be accommodated, is dispersed state equalization of the slurry void becomes small between the resin material in the resin material in the diameter range of 10μm~80μm is paved, the resin material elasticity by Since the cushioning property is exhibited by the elastic yarn, it is possible to obtain an effect that scratching can be suppressed during polishing and the flatness of the object to be polished can be improved.

It is sectional drawing which shows typically the abrasive cloth of embodiment to which this invention is applied. It is a perspective view which expands and schematically shows a part of polishing cloth of an embodiment. It is a top view which expands and schematically shows a part of polishing cloth of an embodiment. It is explanatory drawing which shows the magnitude | size of the space | gap formed between the elastic materials which comprise the polishing cloth of embodiment. It is explanatory drawing which shows the magnitude | size of the space | gap formed between the elastic materials which comprise the polishing cloth of another aspect.

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

(Constitution)
As shown in FIG. 1, the polishing cloth 10 of this embodiment includes a polishing layer 2 having a polishing surface P for polishing an object to be polished. A double-sided tape 5 for attaching the polishing cloth 10 to the polishing machine is bonded to the polishing layer 2 on the surface opposite to the polishing surface P.

  As shown in FIG. 2, the polishing layer 2 is formed by laying in a planar shape so that a large number of cylindrical elastic members 3 having elasticity are circumscribed on the peripheral surface (side surface). The elastic material 3 has a substantially uniform diameter and height. Since the elastic material 3 has a substantially uniform height, the polishing layer 2 is formed with a substantially uniform thickness. Adjacent elastic members 3 are fused at a circumscribed portion to form a fused portion Mp.

  As shown in FIG. 3, a gap Ga defined by the three elastic members 3 is formed between the elastic members 3. Since the elastic material 3 is cylindrical, the gap Ga is formed so as to penetrate in the thickness direction of the polishing layer 2. Since the elastic material 3 has a substantially uniform diameter, the gap Ga is formed with a substantially uniform size. In addition, the polishing layer 2 formed by spreading the elastic material 3 is formed in a state where the gaps Ga are substantially uniformly dispersed. In other words, the polishing surface P is formed in a state in which the openings having a substantially uniform size are substantially uniformly dispersed by the gap Ga.

  The polishing layer 2 is formed by slicing an elastic yarn bundle in which polyurethane elastic yarns are aligned in the longitudinal direction in a direction intersecting the longitudinal direction. As the polyurethane elastic yarn, a monofilament (single fiber) formed by spinning a polyurethane polymer or a multifilament in which a plurality of monofilaments are twisted together can be used. In this example, a monofilament is used. The monofilament has a circular cross section and is spun so that the fineness is in the range of 1 to 70 dtex. The spun monofilament is bundled and sliced so that the length in the longitudinal direction is in the range of 500 to 5000 μm. For this reason, the elastic material 3 constituting the polishing layer 2 has a cylindrical shape having a diameter in the range of 10 to 80 μm and a height in the range of 500 to 5000 μm. The size of the polishing layer 2 and the size of the gap Ga can be adjusted by changing the fineness of the monofilament and the number of monofilaments to be aligned.

Here, the size of the gap Ga formed between the elastic members 3 will be described. As shown in FIG. 4, the gap Ga is defined by three elastic members 3. When the diameter of the elastic member 3 is D, the area of the opening formed in the polishing surface P by the gap Ga can be obtained as follows. That is, if the centers of the three elastic members 3 are M1, M2, and M3, respectively, equilateral triangles M1-M2-M3 having the same side length as the diameter D are formed. The remaining area obtained by subtracting 1/2 of the area of the circular cross section of the elastic member 3 from the area of the regular triangle M1-M2-M3 is the area of the opening of the gap Ga. For this reason, as an area ratio Ar of the opening of the gap Ga formed per unit area of the polishing surface P, the formula 100 × {(D ² × sin 60 ° / 2) − (D / 2) ² × π / 2 } / (D ² × sin 60 ° / 2). According to this formula, the area ratio Ar is approximately 9.3% regardless of the diameter D of the elastic material 3, but in reality, when the monofilament is spun or an elastic yarn bundle is formed, the elastic material 3 The cross section is deformed and the gap Ga is easily reduced. In order to avoid occurrence of polishing scratches, it is desirable to increase the area ratio Ar by suppressing deformation of the cross section of the elastic material 3 and reducing the bundle density when forming the elastic yarn bundle. In this example, the area ratio Ar is adjusted to a range of 10 to 11% by suppressing deformation of the cross section of the elastic member 3. Also, imaginary circles Vc circumscribing the three elastic members 3 on the inner side of the gap Ga are assumed. The diameter φ of the virtual circle Vc can be obtained by the formula D × (1 / cos30 ° −1). The diameter φ approximates the diameter of the gap Ga. The diameter φ is theoretically in the range of 1 to 13 μm if the diameter D of the elastic material 3 is in the range of 10 to 80 μm, but not only the size (diameter D) of the elastic material 3 but also the elastic yarn bundle. It can be adjusted by reducing the bundle density. In this example, 15 dtex monofilament is used, and it is theoretically adjusted to obtain a diameter φ of 5 to 6 μm.

  As shown in FIG. 1, the double-sided tape 5 bonded to the polishing layer 2 is coated with an adhesive on both sides of a base material 5a such as a polyethylene terephthalate (hereinafter abbreviated as PET) film. (Not shown) is formed. The double-sided tape 5 is bonded to the polishing layer 2 with an adhesive layer on one side, and the adhesive layer on the other side is covered with a release paper 5b.

(Manufacturing)
The polishing cloth 10 is a spinning process in which a spinning stock solution containing a polyurethane polymer is spun to obtain monofilaments of polyurethane elastic yarn, a bundle forming process in which the monofilaments are aligned to form an elastic yarn bundle, and the elastic yarn bundle is sliced to a certain length. It is manufactured through a slicing step and a laminating step in which the obtained polishing layer 2 and double-sided tape 5 are bonded together. Hereinafter, it demonstrates in order of a process.

(Spinning process)
In the spinning step, a monofilament is produced by a dry spinning method in which a spinning solution containing a polyurethane polymer is prepared and then discharged from a spinning nozzle into a high-temperature atmosphere. The spinning dope is prepared by reacting an isocyanate group-terminated prepolymer (hereinafter simply referred to as prepolymer) prepared by reacting an organic diisocyanate compound and a diol compound in an organic solvent.

  Examples of the diol compound used for preparing the prepolymer include polyether diols such as polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, polyoxypentamethylene glycol, polyoxyhexamethylene glycol, and polyoxypropylene tetramethylene glycol. Polyester diol compound, polyether polyester diol compound, polylactone diol compound, polycarbonate diol compound, polyester polycarbonate diol produced by a reaction of one or more dicarboxylic acids such as adipic acid, sebacic acid and maleic acid One type or two or more types selected from polymer diol compounds such as compounds can be mentioned. The diol compound used preferably has a number average molecular weight in the range of 1000 to 2500 in view of spinnability. In addition, diol compounds include low molecular diol compounds such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, and 2,3-butanediol, and monool compounds such as butanol and hexanol. May be added and mixed in a small amount, but the above-mentioned polymer diol compound ratio is preferably 80% by weight or more from the viewpoint of spinnability. In this example, polyoxytetramethylene glycol having a number average molecular weight of 1800 is used from among the polyether diol compounds.

  Moreover, as an organic diisocyanate compound used for preparation of a prepolymer, 4,4'-diphenylmethane diisocyanate, 3,3'-dichloro-4,4'-diphenylmethane diisocyanate, m-xylylene diisocyanate, 2,4-tolylene diisocyanate , 2,6-tolylene diisocyanate, hexamethylene diisocyanate, or a combination of two or more. In this example, 4,4'-diphenylmethane diisocyanate is used.

  In the preparation of the prepolymer, the diol compound and the organic diisocyanate compound are mixed at a temperature at which they do not solidify, and reacted under a temperature environment of 90 ° C. or lower for 30 to 120 minutes to obtain a prepolymer having two terminal isocyanate groups. obtain. At this time, the amount of the organic diisocyanate compound relative to the diol compound is adjusted to a range of 110 to 210 mol%, preferably 150 to 190 mol%. If the amount of the organic diisocyanate compound relative to the diol compound is less than 110 mol%, the strength of the resulting monofilament is insufficient, and yarn breakage is liable to occur in the spinning process. On the contrary, if the amount exceeds 210 mol%, the prepolymer Since a large amount of unreacted organic diisocyanate compound remains therein, the proportion of the low molecular weight polyurethane in the polyurethane polymer obtained even when the chain elongation reaction is carried out increases, which is not preferable.

  The resulting prepolymer is polymerized in an organic solvent with a chain extender having two or more active hydrogen groups capable of reacting with isocyanate groups and a terminal terminator having one active hydrogen group capable of reacting with isocyanate groups. To prepare a polyurethane polymer solution. The polymerization method is not particularly limited, and for example, a batch polymerization method or a continuous polymerization method that is directly connected to a spinning nozzle and continuously supplied can also be employed. The polymerization time may be a time at which the polymerization reaction is completed. For example, in the batch polymerization method, the reaction may be usually performed for 30 to 90 minutes. The polymerization temperature is preferably performed in the range of 0 to 70 ° C. If the polymerization temperature is too low, the polymerization takes a long time and the efficiency is deteriorated. On the other hand, if the polymerization temperature is too high, side reactions are promoted, which is not preferable.

  Examples of chain extenders used in the polymerization reaction include ethylenediamine, 1,2-propylenediamine, 1,3-propylenediamine, m-xylylenediamine, p-xylylenediamine, 4,4′-diphenylmethanediamine, and cyclohexylenediamine. , 2,4-tolylenediamine, 2,6-tolylenediamine, hexamethylenediamine, hydrazine, ethylene glycol, 1,4-butanediol, and the like. Examples of the end terminator include dimethylamine, methylethylamine, diethylamine, methyl-n-propylamine, methylisopropylamine, diisopropylamine, di-n-butylamine, di-n-hexylamine, and dicyclohexylamine. it can. In this example, ethylenediamine is used as a chain extender and diethylamine is used as a terminal terminator.

  The organic solvent used for the preparation of the polyurethane polymer solution can dissolve the above-mentioned prepolymer, chain extender, end terminator and reaction product polyurethane polymer. Any polar solvent that is inert to the product is not particularly limited. Examples of such an organic solvent include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), and the like. In this example, DMAc is used as the organic solvent. In addition, a matting agent, a light-resistant agent, an ultraviolet absorber, a gas discoloration preventing agent, etc., which are usually used in the production of polyurethane-based elastic yarns may be added and mixed in the spinning dope as necessary.

  The prepared spinning dope is discharged from a spinning nozzle into a high temperature atmosphere to dry spin the monofilament. The spinning conditions at this time are not particularly limited, and may be those usually used. The fineness of the monofilament can be adjusted by the hole diameter of the spinning nozzle, the discharging speed and winding speed of the spinning dope, the solvent concentration and temperature in the high temperature atmosphere. Although the desired number of multifilaments can be obtained by the number of holes in the spinning nozzle, in this example, the diameter of the spinning nozzle is set so that a monofilament of 15 dtex is obtained, and the number of holes is set to one. The obtained monofilament is wound around a thread tube to obtain a wound body.

(Bundle formation process)
In the bundle forming step, a monofilament having a predetermined length is drawn from the monofilament wound body obtained in the spinning step, and a large number of monofilaments are bundled in the longitudinal direction to produce an elastic yarn bundle. At this time, it is produced so that the size of the cross section intersecting the longitudinal direction of the elastic yarn bundle becomes the size of the polishing layer 2. For example, it is possible to use a mold that matches a desired cross-sectional size. Moreover, you may make it wind up to the beam for adulteration used when producing a textile fabric. The obtained elastic yarn bundle is heat-treated in a heated atmosphere, and adjacent monofilaments are heat-sealed on the peripheral surface to form a fusion part Mp. The heat treatment temperature is set to a temperature that is higher than the temperature at which the monofilament exhibits adhesiveness by heating (adhesion temperature) and at least 10 ° C. lower than the melting point. When the temperature is lower than the adhesion temperature of the monofilament, sufficient fusion cannot be performed and the fusion part Mp may not be formed. On the other hand, if it is too close to the melting point, the fused part Mp becomes too large and the gap Ga is narrowed.

(Slicing process)
In the slicing step, the elastic yarn bundle obtained in the bundle forming step is sliced in a direction that intersects the longitudinal direction at a constant length in the longitudinal direction to produce the polishing layer 2. What is necessary is just to set the length at the time of slicing according to the thickness of the grinding | polishing layer 2, and it sets to 0.5-5 mm in this example. A commonly used slicing machine can be used for slicing. In the obtained polishing layer 2, one surface side constitutes the polishing surface P.

(Lamination process)
In the laminating step, the pressure-sensitive adhesive layer on the one surface side of the double-sided tape 5 is bonded to the surface side opposite to the polishing surface P of the polishing layer 2 obtained in the slicing step. At this time, the release paper 5b is left on the other side of the double-sided tape 5. Thereafter, an inspection such as confirming that there is no adhesion of dirt or foreign matter is performed, and the polishing pad 10 is completed.

  When polishing an object to be polished, the polishing cloth 10 is attached to the polishing surface plate of the polishing machine. When attaching the polishing cloth 10 to the polishing surface plate, the release paper 5b of the double-sided tape 5 is removed, and the exposed adhesive layer is attached to the polishing surface plate. The object to be polished, which is held on a holding platen arranged so as to face the polishing platen, is pressed to the polishing surface P side, and the polishing platen or holding plate is supplied while supplying slurry (polishing liquid containing abrasive grains). The processed surface of the workpiece is polished by rotating the board.

(Action etc.)
Next, the operation and the like of the polishing pad 10 of this embodiment will be described.

  In the present embodiment, the polishing layer 2 is formed by cutting an elastic yarn bundle in which monofilaments of polyurethane elastic yarn are aligned to a certain length, and the height of the elastic material 3 is formed uniformly. For this reason, the thickness of the polishing layer 2 can be made uniform. Further, the gap Ga formed between the elastic members 3 is formed so as to penetrate in the thickness direction of the polishing layer 2. For this reason, polishing scraps generated during the polishing process are easily accommodated in the gap Ga, and clogging of the openings in the polishing surface P is difficult to occur. Since clogging is less likely, dressing work can be reduced during polishing, and polishing efficiency can be improved. Moreover, since it is suppressed that grinding | polishing waste etc. aggregate on the grinding | polishing surface P, the scratch with respect to a to-be-polished object can be suppressed, and flatness improvement can be aimed at.

  In the present embodiment, the polishing layer 2 is composed of an elastic material 3 formed of polyurethane elastic yarn having elasticity. For this reason, since the cushioning property of the elastic material 3 is exhibited at the time of polishing, the polishing pressure applied to the object to be polished can be equalized and the flatness can be improved. In the polishing layer 2, the elastic yarn bundle is heat-processed so that the adjacent elastic material 3 is fused at the fusion part Mp, and the double-sided tape 5 is bonded to one side. For this reason, since the elastic material 3 is fixed at the peripheral surface and the bottom surface (surface opposite to the polishing surface P), the elastic material 3 can be prevented from dropping even if the polishing layer 2 is deformed during polishing. it can.

  Furthermore, in this embodiment, since the elastic material 3 is formed by slicing an elastic yarn bundle, it is formed in a cylindrical shape with a uniform diameter. For this reason, the gap Ga formed between the elastic members 3 is formed in a uniform size and a uniform dispersed state. As a result, the holes in the polishing surface P are made uniform and equalized, so that the dispersed state of the slurry can be equalized during polishing and the flatness of the object to be polished can be improved. The area ratio Ar of the gap Ga formed per unit area of the polishing surface P is adjusted to a range of 9 to 30%. For this reason, it is possible to secure a sufficient storage space for polishing scraps and the like.

  In the polishing cloth 10 having such a polishing layer 2, the pores in the polishing surface P can be made finer and uniform depending on the production conditions of monofilaments of polyurethane elastic yarn, the cushioning property is optimized, the thickness Can be made uniform. For this reason, the polishing layer 2 can be produced in accordance with the characteristics of various objects to be polished. Therefore, the polishing pad 10 can be suitably used for polishing processing of a semiconductor device or the like by the CMP method, for example, where the demand for flatness on the processing surface is advanced.

  In a conventional polishing process, for example, a polishing process of a semiconductor device by a CMP method, a polishing cloth including a resin sheet formed by a dry molding method and having an opening formed on a polishing surface is used. Since the obtained resin sheet is mainly hard and of the independent foam type, there is a problem that the opening formed in the polishing surface is clogged and blocked by abrasive grains or polishing debris. When the opening is closed, the abrasive grains and the like are likely to aggregate, and there is a possibility that the processed surface of the workpiece is scratched. For this reason, a dressing operation is essential, resulting in a decrease in polishing efficiency. Moreover, since a hard resin sheet has insufficient cushioning properties, it needs to be bonded to another sheet having cushioning properties. Furthermore, along with the sophistication of flatness required for the processing surface of semiconductor devices, the demand for polishing performance such as polishing accuracy and polishing efficiency by the CMP method is also increasing. Uniformity is required. Therefore, if the aperture diameter can be made finer and uniform and a polishing cloth having cushioning properties can be obtained, it is possible to meet the demand for high flatness and improve yield and manufacturing efficiency. The present embodiment is an abrasive cloth that can solve these problems.

  In the present embodiment, an example in which the polishing layer 2 is formed by slicing an elastic yarn bundle formed of monofilaments of polyurethane elastic yarn has been shown, but the present invention is not limited to this. For example, it is also possible to form the elastic material 3 formed individually by fixing it so as to spread on the adhesive layer on the one surface side of the double-sided tape 5. In this embodiment, the elastic material 3 is fused at the adjacent portion to form the fused portion Mp. However, the present invention is not limited to this. For example, in the case where the elastic material 3 formed individually is spread on the double-sided tape 5 and the like, a sufficient adhesive force can be obtained even if the side surface (circumferential surface) is not fixed by selecting an adhesive having excellent adhesiveness. Can be obtained.

  In the present embodiment, an example is shown in which monofilaments of polyurethane elastic yarns are aligned to form an elastic yarn bundle, but the present invention is not limited to this. A so-called multifilament composed of a plurality of monofilaments may be used by setting the number of holes in the spinning nozzle in the spinning process of the polyurethane elastic yarn. In this case, for example, while pre-twisting in units of 2 to 10 (slightly twisted so that the monofilaments are in contact with each other), the obtained multifilaments are aligned to form an elastic yarn bundle. Can do. In this way, the void area ratio can be increased compared to an elastic yarn bundle in which monofilaments are aligned. That is, as shown in FIG. 5, when a multifilament composed of seven monofilaments is used, the multifilament elastic material 13 composed of the monofilament elastic material 3 is spread in a plane. Accordingly, in addition to the gap Ga between the monofilaments, a gap Gb larger than the gap Ga is formed between the multifilaments. As a result, since the pores Ga and Gb are formed on the polishing surface P, the dispersion state of the polishing scraps and abrasive grains can be made more uniform.

  Furthermore, in the present embodiment, an example in which a monofilament of polyurethane elastic yarn is produced by a dry spinning method is shown, but the present invention is not limited to this, and it is produced by a melt spinning method or a wet spinning method. Also good. Further, instead of the circular cross section, it may be an elliptical or square shaped irregular cross section. Considering the uniform size of the gap Ga and the uniform dispersion state, it is preferable to have a circular cross section. Furthermore, instead of producing an elastic yarn only with a polyurethane resin, any one of the two-component systems having a sea-island structure, a side-by-side structure, and a core-sheath structure to produce an elastic yarn bundle, The components may be dissolved and removed. Although not particularly mentioned in the present embodiment, in the dry spinning method and the melt spinning method, the filament immediately after spinning is in a melted and softened state. The elastic yarn bundle can be formed by aligning without providing (oilless state). If it does in this way, an adjacent filament will be fused in the process in which a filament solidifies by cooling, and a heat treatment process can be omitted.

  Furthermore, in the present embodiment, an example in which a monofilament having a fineness in a range of 1 to 70 dtex is spun and an elastic yarn bundle is sliced to a length of 0.5 to 5 mm is shown, but the present invention is limited to these. It is not a thing. About the length to slice, since it becomes the thickness of the polishing layer 2, what is necessary is just to adjust at the time of a slice according to desired thickness. In consideration of the size of the gap Ga and the porosity, the fineness is preferably in the range of 2 to 30 dtex, more preferably in the range of 4 to 20 dtex.

  Furthermore, in this embodiment, the area ratio Ar of the opening of the gap Ga formed per unit area of the polishing surface P is in the range of 10 to 11%, and the diameter φ of the virtual circle Vc in the gap Ga is 5 to 6 μm. Examples of ranges are shown, but the present invention is not limited to these. As described above, the area ratio Ar is preferably adjusted so as to increase by suppressing cross-sectional deformation of the elastic material 3, reducing the bundle density of the elastic yarn bundle, and the like from the viewpoint of avoiding polishing scratches. The area ratio Ar is preferably in the range of 9 to 30%, and more preferably in the range of 10 to 20%. Further, as described above, the diameter φ of the virtual circle Vc is in the range of 1 to 12 μm when the monofilament fineness is in the range of 1 to 70 dtex. It is in the range of 2 to 8 μm, more preferably in the range of 3 to 7 μm.

  Although not particularly mentioned in the present embodiment, the polishing layer 2 has at least a light transmission part that allows light transmission for optically detecting the polishing state of the object to be polished. It may be. This means that, for example, if some of the elastic material 3 in the part forming the light transmission part is extracted, the light transmission part penetrating over the entire thickness direction of the polishing layer 2 can be formed. In this way, for example, a light-emitting element such as a light-emitting diode provided on the polishing machine side or a light-receiving element such as a phototransistor detects the polishing state of the processing surface of the object to be polished through the light transmitting part during polishing. can do. As a result, the end point of the polishing process can be properly detected, and the polishing efficiency can be improved.

  Further, although not particularly mentioned in the present embodiment, the grinding process may be performed on the polishing surface P side of the polishing layer 2 or the surface side opposite to the polishing surface P. In this way, the thickness of the polishing layer 2 can be made more uniform. Further, a base material such as a resin sheet having flexibility may be bonded between the polishing layer 2 and the double-sided tape 5. In this way, handling of the relatively flexible polishing layer 2 can be facilitated.

  Next, examples of the polishing pad 10 manufactured according to the present embodiment will be described. In addition, it writes together also about the polishing cloth of the comparative example manufactured for the comparison.

Example 1
In Example 1, a spinning dope was prepared as follows, and a polishing layer 2 was prepared from monofilaments of polyurethane elastic yarns obtained to produce a polishing cloth 10. That is, 2870 parts of polyoxytetramethylene glycol having a number average molecular weight of 1800 and 595 parts of 4,4′-diphenylmethane diisocyanate were mixed at 45 ° C. and reacted at 75 ° C. for 80 minutes to obtain 3465 parts of prepolymer. Obtained. The isocyanate group content at this time was 1880 g in 100 g of the prepolymer. Separately, 44 parts of ethylenediamine as a chain extender and 6 parts of diethylamine as a terminal terminator are added to 1262 parts of DMAc cooled to 0 ° C. and stirred well to obtain a chain extender and a terminal terminator. A mixed solution of was obtained. After 3400 parts of the prepolymer obtained above was added to 5896 parts of DMAc cooled to 0 ° C. and sufficiently stirred, the active hydrogen groups of the chain extender and the end terminator were equal to the isocyanate group of the prepolymer. A mixed solution of a chain extender and a terminal terminator was added so as to have a molar ratio, and a polyurethane polymer solution having a concentration of 35% was prepared to prepare a spinning dope.

  The obtained spinning dope was dry-spun using a spinning nozzle having one orifice with a diameter of 0.2 mm. The spinning speed was set at 300 m / min, and it was wound around a paper tube while stretching 20% to obtain a 15 dtex monofilament wound body. An elastic yarn bundle was formed from this monofilament, sliced and then heat-treated to prepare a polishing layer 2 having a thickness of 2.0 mm. Polishing cloth 10 was manufactured by pasting together the obtained polishing layer 2 and double-sided tape 5.

(Comparative Example 1)
In Comparative Example 1, a dispersion in which water is dispersed in a terminal isocyanate group-containing urethane prepolymer (hereinafter simply referred to as prepolymer), ethylenediamine as a diamine compound, and polytetramethylene glycol having a number average molecular weight of about 1000 as a polyol compound is mixed. And then reacting to form a polyurethane foam. As the prepolymer, 270 parts of 2,4-tolylene diisocyanate (2,4-TDI), 292 parts of polytetramethylene glycol having a number average molecular weight of about 1000, and 65 parts of diethylene glycol were obtained. .7% was used. The prepolymer, ethylenediamine and dispersion were mixed at a weight ratio of 100 parts: 21 parts: 5.5 parts. By slicing the polyurethane foam, a urethane sheet having a thickness of 2.0 mm was produced. The abrasive cloth of Comparative Example 1 was produced by bonding the obtained urethane sheet and the double-sided tape 5 together.

(Evaluation)
Next, using the polishing cloths of the examples and comparative examples, the aluminum substrate for hard disk was polished under the following polishing conditions, and the polishing rate was measured. As the polishing rate, the amount of polishing per minute was calculated from the weight reduction of the aluminum substrate before and after polishing. Further, the presence or absence of scratches on the aluminum substrate and the presence or absence of clogging on the polishing surface P of the polishing cloth were determined visually. The measurement results of the polishing rate, scratch and clogging are shown in Table 1 below.
(Polishing conditions)
Polishing machine used: Speedfam, 9B-5P polishing machine Polishing speed (rotation speed): 30 rpm
Processing pressure: 100 g / cm ²
Slurry: Alumina slurry (pH: 2.0)
Slurry supply amount: 100cc / min
Workpiece: Aluminum substrate for hard disk (outer diameter 95mmφ, inner diameter 25mm, thickness 1.27mm)

  As shown in Table 1, the polishing cloth of Comparative Example 1 showed a polishing rate of 0.54 mg / min. However, many scratches were observed on the processed surface of the object to be polished, and clogging of the openings was observed on the polishing surface of the polishing cloth. On the other hand, the polishing cloth 10 of Example 1 showed a polishing rate of 0.55 mg / min and was able to perform sufficient polishing. Further, no scratch was observed on the processed surface, and it was confirmed that excellent flatness was obtained. Furthermore, clogging of the gap Ga was not observed on the polishing surface P of the polishing pad 10.

  The present invention provides an abrasive cloth capable of suppressing scratches and improving the flatness of an object to be polished, and thus contributes to the manufacture and sale of the abrasive cloth, and thus has industrial applicability.

Ga gap P Polishing surface 2 Polishing layer 3 Elastic material (resin material)
10 Abrasive cloth

Claims (10)

In a polishing cloth including a polishing layer having a polishing surface for polishing an object to be polished, the polishing layer is flat so that a large number of columnar resin materials having elasticity and a uniform height are circumscribed on the side surface. A polishing cloth , wherein the resin material is a polyurethane elastic yarn having a diameter in the range of 10 μm to 80 μm .   The abrasive cloth according to claim 1, wherein a portion that circumscribes the resin material is fixed.   The polishing cloth according to claim 2, wherein the polishing layer has an area ratio of voids formed between the resin materials in a range of 9% to 30% per unit area of the polishing surface.   The abrasive cloth according to claim 3, wherein the resin material has a cylindrical shape with a uniform diameter. The abrasive cloth according to claim 4, wherein the resin material has a height in a range of 500 μm to 5000 μm. 3. The polishing layer according to claim 1, wherein an elastic yarn bundle in which the polyurethane elastic yarns are aligned in a longitudinal direction is cut and formed in a direction intersecting the longitudinal direction. The polishing cloth as described.   The abrasive cloth according to claim 6, wherein the elastic yarn bundle is formed by heat-sealing the polyurethane elastic yarn adjacent thereto.   The polishing cloth according to claim 7, wherein the polyurethane elastic yarn is a monofilament or a multifilament in which a plurality of the monofilaments are twisted together.   The polishing cloth according to claim 8, wherein the monofilament has a fineness in a range of 1 dtex to 70 dtex.   The polishing cloth according to claim 7, wherein the gaps formed between the resin materials are formed in a uniform size and a uniform dispersion state.

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