Polishing pad

Abstract

To provide a polishing pad which can improve self-dress property, and a method for manufacturing the same.SOLUTION: A polishing pad includes a polishing layer containing a polyurethane resin, wherein the polyurethane resin contains at least one of fatty acid metal salt particles having 8 to 24 carbon atoms, metal alkylsulfosuccinate particles and metal alkylsulfate particles. By containing the fatty acid metal salt particles and the metal alkylsulfosuccinate particles, elongation of the polyurethane resin in friction is suppressed, it is presumed that the particles contribute to the self-dress property, the fatty acid metal salt particles and the metal alkylsulfosuccinate particles are sufficiently small, and accordingly occurrence of scratches can be suppressed as much as possible.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a polishing pad, and more particularly to a polishing pad having a polishing layer containing a polyurethane resin and excellent in self-dressing property.

Background Art

[0002] Today, so-called chemical mechanical polishing (CMP) is performed, in which polishing is carried out while supplying a slurry between a polishing pad and a workpiece to be polished, such as an optical material, a semiconductor wafer, a hard disk substrate, a glass substrate for liquid crystal, and a semiconductor device. Particularly in the finishing step of the above CMP, a polishing pad having a polishing layer in which innumerable bubbles are formed inside a polyurethane resin is used. When manufacturing this polishing pad, a polyurethane resin-containing solution applied to a film-forming base material is immersed in a coagulating liquid and coagulated and regenerated, and it is manufactured by a so-called wet film-forming method. When polishing a workpiece using the above polishing pad, the slurry is accommodated in the bubbles opened on the polishing surface. However, a clogging phenomenon of the opening occurs on the polishing surface of the polishing pad during the polishing process. This refers to a state in which the resin portion that is not opened is stretched by the friction during polishing, and the opened portion is covered with the stretched resin. When the opening is clogged, the retention of the polishing slurry deteriorates, and the polishing performance of the polishing pad is deteriorated. Therefore, so-called dressing is performed in which the polishing surface of the polishing pad is cut to expose the opening. However, when dressing is performed, the polishing operation is interrupted, so there is a problem that the polishing efficiency is lowered. In addition, since the thickness of the polishing pad is reduced by cutting, there is a problem that the product life of the polishing pad is lowered. Therefore, a polishing pad having so-called self-dressing property is known, in which appropriate brittleness is imparted to the polishing layer so as to maintain the surface roughness of the polishing surface without closing the opening of the polishing pad during polishing (Patent Document 1). Patent Document 1 discloses a polishing pad in which carbon black or colloidal silica is incorporated into the polishing layer to provide self-dressing properties. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Patent No. 5371661 [Overview of the project] [Problems that the invention aims to solve]

[0004] However, if an excessive amount of carbon black is added to the polishing layer, as described in Patent Document 1 above, primary aggregates (aggregates) formed by the aggregation of several to tens of carbon black particles further aggregate into secondary aggregates (aglomerates), forming large aggregates of tens to hundreds of micrometers. As a result, when the secondary aggregates of carbon black are exposed on the polishing surface, or when these secondary aggregates become pad debris, they cause scratches on the workpiece. On the other hand, polishing pads with reduced carbon black and added colloidal silica had the problem of increased viscosity of the polyurethane resin, causing deformation of the openings on the polishing surface and worsening self-dressing properties. In view of these problems, the present invention provides a polishing pad capable of improving self-dressing properties. [Means for solving the problem]

[0005] In other words, the invention of claim 1 is a polishing pad having a polishing layer containing polyurethane resin, Numerous openings, consisting of air bubbles, are formed on the polished surface of the above-mentioned polishing layer, and a mesh-like polyurethane resin is exposed on the polished surface. The polyurethane resin described above is characterized by containing at least one of the following: fatty acid metal salt particles having 8 to 24 carbon atoms, alkyl sulfosuccinate metal salt particles, or alkyl sulfate metal salt particles. [Effects of the Invention]

[0006] According to the polishing pad of the invention of claim 1 above, fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, and alkyl sulfate metal salt particles are dispersed in the polishing layer. When the mesh-like polyurethane resin exposed on the polished surface is stretched by friction during polishing, By making it easier to tear, good self-dressing properties can be achieved. [Brief explanation of the drawing]

[0007] [Figure 1] Photographs of Example 1 and Comparative Example 1 observed at 200x magnification under a microscope. [Modes for carrying out the invention]

[0008] The polishing pad and its manufacturing method according to this embodiment will now be described. The polishing pad of this embodiment is used for chemical mechanical polishing (CMP) and is used to polish objects such as optical materials, semiconductor wafers, hard disk substrates, liquid crystal glass substrates, and semiconductor devices. The polishing pad of this embodiment has a polishing layer containing a polyurethane resin in which countless air bubbles are formed inside, and the polishing surface for polishing the workpiece has countless openings formed by the air bubbles. Furthermore, the polishing pad of this embodiment may have grooves formed on its polishing surface, similar to conventionally known polishing pads, and a support layer made of a resin sheet or resin-impregnated nonwoven fabric is provided on the surface opposite to the polishing surface.

[0009] The polishing layer constituting the polishing pad described above is made up of a polyurethane resin sheet that has been wet-formed based on the manufacturing method described later. The polyurethane resin mentioned above can be selected from various conventionally known polyurethane resins depending on the intended use. For example, polyester-based, polyether-based, or polycarbonate-based resins can be used. Examples of polyester resins include polymers of polyester polyols, such as ethylene glycol or butylene glycol, and adipic acid, and diisocyanates such as diphenylmethane-4,4'-diisocyanate. Examples of polyether-based resins include polymers of polyether polyols such as polytetramethylene ether glycol and polypropylene glycol with isocyanates such as diphenylmethane-4,4'-diisocyanate. Examples of polycarbonate-based resins include polymers of polycarbonate polyols and isocyanates such as diphenylmethane-4,4'-diisocyanate. These resins can be readily available on the market, such as "Crisbon" manufactured by DIC Corporation, "Samplen" manufactured by Sanyo Chemical Industries, Ltd., or "Rezamin" manufactured by Dainichi Seika Kogyo Co., Ltd.

[0010] Furthermore, the polyurethane resin sheet constituting the polishing layer of the polishing pad in this embodiment contains at least one of fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, and alkyl sulfate metal salt particles. The fatty acid metal salt particles, alkyl sulfosuccinates, and alkyl sulfates contained in the above polyurethane resin reduce the viscosity of the resin during the manufacturing of the polyurethane resin sheet that constitutes the polishing layer, thereby contributing to the self-dressing properties of the polishing pad. The above-mentioned fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, and alkyl sulfate metal salt particles are reaction products of fatty acid alkali compound salts, alkyl sulfosuccinate alkali compound salts, and alkyl sulfate alkali compound salts obtained by reacting fatty acids, alkyl sulfosuccinate, and alkyl sulfate with a monovalent alkali compound, and divalent metal salts. These are contained in the polyurethane resin sheet during the manufacturing process of the polishing pad described below.

[0011] The fatty acids, alkyl sulfosuccinates, and alkyl sulfates used as raw materials for the above-mentioned fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, and alkyl sulfate metal salt particles preferably have 6 to 24 carbon atoms in the fatty acids or alkyl groups that constitute them, and more preferably have 8 to 18 carbon atoms. The alkyl groups may be in either a linear or branched configuration. Examples of the above fatty acids include caprylic acid, capric acid, lauric acid, myristic acid, myristooleic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, linoleic acid, behenic acid, and erucic acid. Examples of alkyl sulfosuccinates include dioctyl sulfosuccinate and dilauryl sulfosuccinate. Examples of alkyl sulfates include lauryl sulfate, myristyl sulfate, stearyl sulfate, oleyl sulfate, cetyl sulfate, and dodecyl sulfate. The average particle size of the fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, and alkyl sulfate metal salt particles is preferably 3 μm or less, and more preferably 1 μm or less. A particle size of 3 μm or less avoids scratching the workpiece due to the fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, and alkyl sulfate metal salt particles, ensuring sufficient self-dressing properties for polishing without significantly contributing to the polishing process. While there is no particular lower limit, it can be as low as 10 nm. Furthermore, calcium and magnesium are preferred as the divalent metals used as raw materials for the above-mentioned fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, and alkyl sulfate metal salt particles, and it is preferable that these metals become insoluble in water when reacted with fatty acids, alkyl sulfosuccinate, and alkyl sulfate. Examples of divalent metal salts include calcium chloride, calcium acetate, magnesium chloride, and magnesium sulfate. Specific examples of the above fatty acid metal salt particles, alkylsulfosuccinic acid metal salt particles, and alkylsulfuric acid metal salt particles include calcium myristate, magnesium myristate, calcium stearate, magnesium stearate, calcium dioctylsulfosuccinate, calcium didodecylsulfate, magnesium dioctylsulfosuccinate, and magnesium didodecylsulfate.

[0012] The metal constituting the above fatty acid metal salt particles, alkylsulfosuccinic acid metal salt particles, and alkylsulfuric acid metal salt particles in the polishing layer is preferably contained in a proportion of 50 to 200 ppm. If these proportions are less than 50 ppm, the self-dressing property is insufficient, the openings on the polished surface are likely to be blocked and smoothed, and when they exceed 200 ppm, the wear resistance deteriorates and the product life becomes short.

[0013] Thus, when polishing an object to be polished using a polishing pad in which the polishing layer contains fatty acid metal salt particles, alkylsulfosuccinic acid metal salt particles, and alkylsulfuric acid metal salt particles, the fatty acid metal salt particles, alkylsulfosuccinic acid metal salt particles, and alkylsulfuric acid metal salt particles dispersed in the polishing layer are prevented from restricting the elongation of the polyurethane resin and blocking the openings on the polished surface.

[0014] Furthermore, the polishing layer of the polishing pad of this embodiment may contain at least one filler selected from the group consisting of carbon black and silica, or other fillers other than carbon black or silica may be used in combination. Examples of the other fillers include organic pigments such as azo pigments and inorganic pigments such as titanium oxide. However, when using the above carbon black as a filler in this embodiment, it is desirable that the carbon black in the polishing layer be up to 3 parts by mass with respect to 100 parts by mass of the polyurethane resin. As mentioned above, carbon black forms large aggregates, so if the proportion of carbon black is increased above the above-mentioned ratio, while it may create self-dressing properties when polishing the workpiece, there is a risk of scratches occurring due to pad debris derived from carbon black.

[0015] Furthermore, the polishing pad of this embodiment may contain, in addition to the above components, additives such as crosslinking agents, dispersants, water repellents, and film-forming stabilizers in the polishing layer, to the extent that it does not impair the effects of the present invention.

[0016] While there are no particular restrictions on the thickness of the polishing layer constituting the polishing pad described above, it is preferable that it be approximately 0.3 to 2.0 mm thick. The density of the above polishing layer is 0.15 to 0.50 g / cm³. 3 Preferably, 0.18-0.35 g / cm³ 3 It is preferable that it be so. When the density is within the above range, the polishing characteristics (polishing rate, shape) can be easily controlled.

[0017] The compression ratio of the polished layer is preferably 1-70%, more preferably 3-60%, even more preferably 4-40%, and particularly preferably 5-20%. When the compression ratio is within the above range, a good balance between scratch performance and polishing rate can be maintained. The compressive modulus of the polished layer is preferably 50-100%, more preferably 70-100%, and even more preferably 80-100%. If the compressive modulus is within the above range, the deformation of the pad due to the polishing load can be reduced, and the polishing characteristics can be stabilized. The above compressibility and compressive modulus can be determined in accordance with the Japanese Industrial Standard (JIS L 1021) using a Shopper-type thickness measuring instrument (pressure surface: circular with a diameter of 1 cm).

[0018] The Shore A hardness of the polished layer is preferably 1 to 40 degrees, more preferably 5 to 38 degrees, even more preferably 10 to 35 degrees, and particularly more preferably 15 to 30 degrees. When the Shore A hardness is within the above range, a good balance between scratch performance and polishing rate can be maintained. The above Shore A hardness can be determined according to the Japanese Industrial Standard (JIS K7311).

[0019] The average diameter of the openings that open to the polished surface of the polished layer is preferably in the range of 20 to 80 μm, more preferably 25 to 70 μm, and even more preferably 30 to 60 μm. Furthermore, the porosity of the openings that open into the polished surface is preferably in the range of 5 to 50%, more preferably 7 to 35%, and even more preferably 10 to 30%. The average hole diameter can be calculated as the average of the circle equivalent diameters obtained by binarizing the surface image of the polyurethane resin sheet and calculating from the area and number of each hole, and the hole ratio can be calculated as the ratio (%) of the area of ​​the openings to the surface area of ​​the polished surface. When the average hole diameter and opening ratio are within the above range, the slurry retention is good, and a stable polishing rate can be obtained.

[0020] Next, a method for manufacturing the polishing pad according to this embodiment will be described. Here, a method for manufacturing the polyurethane resin sheet that constitutes the polishing layer of the polishing pad will be described. The process of forming the polishing surface by buffing and the process of attaching the resin sheet as a support layer to the side opposite to the polishing surface are conventionally known, so their explanation will be omitted. First, a preparation step is performed in which the polyurethane resin and solvent are mixed to prepare a polyurethane resin-containing solution. As the polyurethane resin mentioned above, the polyurethane resin can be the one described above, and preferably has a resin modulus of 1 to 20 MPa, preferably 3 to 15 MPa, and most preferably 4 to 12 MPa. Examples of the above solvents include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), acetone, acetonitrile, N-methylpyrrolidone (NMP), and mixtures thereof. The ratio of polyurethane resin to solvent is preferably 100 to 800 parts by mass of solvent per 100 parts by mass of polyurethane resin, more preferably 150 to 600 parts by mass of solvent per 100 parts by mass of polyurethane resin, and even more preferably 200 to 500 parts by mass of solvent per 100 parts by mass of polyurethane resin.

[0021] To manufacture the polishing pad of this embodiment, the polyurethane resin sheet contains at least one of fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, or alkyl sulfate metal salt particles. The fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, and alkyl sulfate metal salt particles of the present invention can be obtained, for example, by a double decomposition method in which one of a fatty acid alkali compound salt, an alkali metal alkyl sulfosuccinate salt, or an alkali metal alkyl sulfate salt reacts with a calcium salt or a magnesium salt in an aqueous solution. Examples of calcium salts include calcium chloride and calcium acetate, while examples of magnesium salts include magnesium chloride and magnesium sulfate.

[0022] The method for imparting fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, and alkyl sulfate metal salt particles to a polyurethane resin sheet is not particularly limited. For example, one method involves impregnating a polyurethane resin sheet in a dispersion of fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, or alkyl sulfate metal salt particles in a dispersion medium such as water, then lifting and drying the sheet; another method involves wet-forming a polyurethane resin containing fatty acid alkali compound salts, alkyl sulfosuccinate alkali compound salts, or alkyl sulfate alkali compound salts, impregnating the resulting polyurethane resin sheet in a dispersion of divalent metal salts in a dispersion medium such as water, then lifting and drying the sheet; another method involves internally adding fatty acid alkali compound salts, alkyl sulfosuccinate alkali compound salts, or alkyl sulfate alkali compound salts to a polyurethane resin, immersing the polyurethane resin viscous body in a coagulation bath to which divalent metal salts have been added, and after the resin has coagulated and regenerated, removing it from the coagulation bath and washing and drying it; and yet another method involves internally adding fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, or alkyl sulfate metal salt particles to a polyurethane resin and wet-forming the film. By applying fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, and alkyl sulfate metal salt particles to a polyurethane resin sheet using the method described above, fine particles smaller than carbon black aggregates can be attached to the surface of the polyurethane foam cell, improving self-dressing properties without causing scratches to the workpiece.

[0023] When wet-forming a film by incorporating the above-mentioned fatty acid alkali compound salt, alkyl sulfosuccinate metal salt, or alkyl sulfate metal salt into a polyurethane resin, it is preferable that the polyurethane resin-containing solution contains 0.1 to 15.0 parts by mass per 100 parts by mass of polyurethane resin, more preferably 0.5 to 10.0 parts by mass, and even more preferably 0.5 to 5.0 parts by mass. Within this range, the required amount of fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, and alkyl sulfate metal salt particles can be included.

[0024] In addition to the components mentioned above, additives such as fillers, foaming aids, and film-forming stabilizers may also be added to the polyurethane resin-containing solution. Fillers and additives may be added to the solvent before dissolving the polyurethane resin in the solvent, or they may be added to the solution after the polyurethane resin has been dissolved in the solvent. In this case, it is possible to use fillers such as carbon black, but if carbon black is used, it is preferable that the carbon black is included in a proportion of less than 3 parts by mass relative to the polyurethane resin. Furthermore, the polishing pad of the present invention may or may not contain carbon black in the polyurethane resin sheet, but it is preferable that it does not contain carbon black. When polyurethane resin sheets contain carbon black, the rigidity of the pad improves, but scratches are more likely to occur on the surface of the workpiece. By not including carbon black in the polyurethane resin sheets, the problem of scratching can be avoided, and the occurrence of defects can be further reduced. For similar reasons, it is preferable that the polishing pad of the present invention contains a polyurethane resin sheet that does not contain fillers other than carbon black.

[0025] Next, a coating step is performed in which the polyurethane resin-containing solution obtained in the above preparation step is applied to the film-forming substrate. As the film-forming substrate mentioned above, there are no particular restrictions as long as it is a film-forming substrate commonly used in this art, but flexible polymer films such as polyester films and polyolefin films, and nonwoven fabrics impregnated and fixed with elastic resin can be used. In the coating process, a knife coater or reverse coater is used to apply the prepared polyurethane resin-containing solution to the film-forming substrate in a nearly uniform manner.

[0026] Next, a solidification process is performed in which the polyurethane resin-containing solution is immersed in a solidification solution to solidify the polyurethane resin. This process is known as the wet film formation method, in which a film-forming substrate coated with a polyurethane resin-containing solution is immersed in a solidification solution to solidify and regenerate the polyurethane resin. In this embodiment, the coagulation solution can be water or a mixed solution of water and a polar solvent such as DMF. Examples of polar solvents include water-miscible organic solvents used to dissolve polyurethane resin, such as DMF, DMAc, THF, DMSO, NMP, and acetone. The concentration of the polar solvent in the mixed solvent is preferably 0.5 to 30% by mass. The solution should be maintained at a temperature of 15 to 50°C. In the solidification process, the polyurethane resin-containing solution applied to the film-forming substrate is immersed in a solidification solution for 10 to 100 minutes, causing the polyurethane resin to solidify through wet solidification and displacement.

[0027] Next, a washing and drying process is performed on the obtained polyurethane resin sheet to remove any remaining solvent and to dry it. While water is a common cleaning solution used for cleaning, additional steps such as cleaning with dilute acid, chelation cleaning, neutralization cleaning, and cleaning with pure water may also be added. After washing, the polyurethane resin sheet is dried. For example, it is dried in a dryer at 100-180°C for 5-30 minutes.

[0028] Next, the following experiment was conducted on the polishing pads mentioned above. In this experiment, the polishing pads of Examples 1 and 2 and Comparative Examples 1 and 2 according to the present invention were manufactured as follows.

[0029] (Example 1) To 100 parts of a polyester polyurethane resin-containing DMF solution (solid content concentration 30% by mass), 5 parts of purified water, 1 part of a dimethylformamide solution containing 30% by weight of cellulose propionate acetate, and 50 parts of DMF containing calcium stearate particles (Nissan Electol MC-2, manufactured by Nippon Oil & Fats Co., Ltd.) dispersed at a solid content of 150 ppm relative to the resin were added and mixed to prepare a polyurethane resin-containing solution. A PET film was prepared as a substrate for film formation, and the above resin solution was applied to it. In the solidification process, polyurethane resin was impregnated in a solidification solution consisting of a 10% by mass DMF aqueous solution at 18°C. After the resin solidified and regenerated, it was removed from the solidification bath, the film-forming substrate was peeled off from the polyurethane sheet, and then the polyurethane sheet was immersed in a washing solution consisting of water to wash away the DMF solvent and dry to obtain the polyurethane sheet. The amount of calcium contained in the polyurethane sheet was measured using an ICP emission spectrometer (Avio 500, manufactured by PerkinElmer Japan Co., Ltd.), and the calcium content was found to be 131 ppm. The surface of the obtained polyurethane sheet was buffed, and a PET resin substrate with a thickness of 0.188 μm was bonded to the side opposite the buffed surface with adhesive. Double-sided tape was then bonded to the side of the resin substrate that was not bonded to the polyurethane sheet. The surface of the polyurethane sheet was embossed from the front side to produce a polishing pad.

[0030] (Example 2) To 100 parts of a polyester polyurethane resin-containing DMF solution (solid content concentration 30% by mass), 5 parts of purified water, 0.8 parts of sodium dioctyl sulfosuccinate, 1 part of a dimethylformamide solution containing 30% by weight of cellulose propionate acetate, and 50 parts of the solvent DMF were added and mixed to prepare a polyurethane resin-containing solution. In the solidification process, a solidification solution consisting of a 10% by mass DMF aqueous solution at 18°C ​​was used, to which calcium acetate was added to achieve a calcium concentration of 20 ppm. The polyurethane resin was impregnated with this solution, and after the resin solidified and regenerated, it was removed from the solidification bath. The film-forming substrate was peeled off the polyurethane sheet, and then the polyurethane sheet was immersed in a washing solution consisting of water to wash away the DMF solvent and dried to obtain the polyurethane sheet. The amount of calcium contained in the polyurethane sheet was measured using the same ICP emission spectrometer as in Example 1, and the calcium content was found to be 106 ppm. Subsequently, the same processing as in Example 1 was performed to obtain a polishing pad.

[0031] (Comparative Example 1) To 100 parts of a polyester polyurethane resin-containing DMF solution (solid content concentration 30% by mass), 5 parts of purified water, 0.8 parts of sodium dioctyl sulfosuccinate, 1 part of a dimethylformamide solution containing 30% by weight of cellulose propionate acetate, and 50 parts of the solvent DMF were added and mixed to prepare a polyurethane resin-containing solution. A PET film was prepared as a substrate for film formation, and the above resin solution was applied to it. In the solidification process, polyurethane resin was impregnated in a solidification solution consisting of a 10% by mass DMF aqueous solution at 18°C. After the resin solidified and regenerated, it was removed from the solidification bath, the film-forming substrate was peeled off from the polyurethane sheet, and then the polyurethane sheet was immersed in a washing solution consisting of water to wash away the DMF solvent and dry to obtain the polyurethane sheet. The amount of calcium contained in the polyurethane sheet was measured using the same ICP emission spectrometer as in Example 1, and the calcium content was found to be 10 ppm. Subsequently, the same processing as in Example 1 was performed to obtain a polishing pad.

[0032] (Comparative Example 2) To 100 parts of a polyester polyurethane resin-containing DMF solution (solid content concentration 30% by mass), 5 parts of purified water, 0.8 parts of sodium dioctyl sulfosuccinate, 1 part of a dimethylformamide solution containing 30% by weight of cellulose propionate acetate, 50 parts of DMF as a solvent, and 24 parts of a DMF dispersion containing 30% carbon black as a pigment were added and mixed to prepare a polyurethane resin-containing solution. A PET film was prepared as a substrate for film formation, and the above resin solution was applied to it. In the solidification process, polyurethane resin was impregnated in a solidification solution consisting of a 10% by mass DMF aqueous solution at 18°C. After the resin solidified and regenerated, it was removed from the solidification bath, the film-forming substrate was peeled off from the polyurethane sheet, and then the polyurethane sheet was immersed in a washing solution consisting of water to wash away the DMF solvent and dry to obtain the polyurethane sheet. The amount of calcium contained in the polyurethane sheet was measured using the same ICP emission spectrometer as in Example 1, and the calcium content was found to be 14 ppm. Subsequently, the same processing as in Example 1 was performed to obtain a polishing pad.

[0033] [Table 1]

[0034] Table 1 above shows the results of evaluations of abrasion resistance, the state of openings formed on the polished surface after polishing, and self-dressing properties for Examples 1 and 2 and Comparative Examples 1 and 2. First, for each example and comparative example, the amount of wear on the polyurethane sheet (the sheet before buffing the polishing surface and forming openings) was measured and evaluated based on the criteria described below. For measuring the amount of wear, a friction wear test was performed using a tabletop single-sided polishing device under the following test conditions, and the difference in average height between the sample before polishing and the sample after polishing was measured as the amount of wear. <Abrasion test conditions> Polishing machine used: Speedfam Co., Ltd., product name "FAM-12BS" Plate rotation speed (scratching pad rotation speed): 30 rpm Flow rate: 100ml / min (pure water) Abrasive material: #2000 sandpaper Surface pressure: 80g / cm 2 Rotation speed: 30 rpm Test time: 3 minutes Number of polishing: 3

[0035] (Evaluation of abrasion resistance) For the evaluation of wear resistance, the thickness of the test specimen was measured at four arbitrary locations before the wear test, and the average value was calculated. This specimen was then subjected to the test, and the thickness of the test specimen after wear was measured at four arbitrary locations and the average value was calculated. The amount of thickness reduction was determined from the difference between the two values. The thickness was measured using a thickness gauge, and measurements were taken to the nearest 0.1 μm. If the thickness reduction amount was 500 μm or less, it was evaluated as having suitable wear resistance for use as an abrasive pad and received a "○" rating. In contrast, if the thickness exceeds 500 μm, wear is significant and the product life is shortened, making it unsuitable as an abrasive pad, and it was evaluated as "×".

[0036] (Evaluation of the opening state) After the polishing test was completed, the polished surface of the polishing pad was observed using a microscope (VH-5500, manufactured by KEYENCE) to observe the shape of the openings in the polished surface. A circle (○) indicates that the opening in the polished surface remains undeformed, while a cross (×) indicates that the resin is stretched, causing the resin around the opening to become fuzzy and stretched. Figure 1 shows microscope images (magnification 200x) of Example 1 and Comparative Example 1 when the aperture state was evaluated. Figure 1(a) shows the image of Example 1, and Figure 1(b) shows the image of Comparative Example 1.

[0037] (Evaluation of self-dressing ability) The self-dressing properties were evaluated based on the amount of wear reduction in the abrasion test described above and the shape of the openings that form on the polished surface. Specifically, if the change in thickness before and after the abrasion test was within the range of 500 μm or less, and the opening condition was good, the self-dressing property was evaluated as ○. If at least one of the wear amount or the opening condition was unsuitable, the self-dressing property was evaluated as ×.

[0038] The results of the above experiment showed that in Examples 1 and 2, both the opening state and wear resistance were good, and the self-dressing properties were also good. In contrast, while Comparative Example 1 had no wear resistance issues, the opening was found to be blocked after polishing. In contrast, Comparative Example 2, which included carbon black, showed good aeration of the polished surface, but was prone to wear. Considering the above experimental results, it is presumed that the inclusion of fatty acid metal salt particles and alkyl sulfosuccinate metal salt particles in the polishing pads of Examples 1 and 2 suppresses the elongation of the polyurethane resin during friction, contributing to self-dressing properties. Furthermore, it is presumed that the occurrence of scratches is minimized as much as possible because the fatty acid metal salt particles and alkyl sulfosuccinate metal salt particles are sufficiently small.

Claims

1. In a polishing pad having a polishing layer containing polyurethane resin, Numerous openings, consisting of air bubbles, are formed on the polished surface of the above-mentioned polishing layer, and a mesh-like polyurethane resin is exposed on the polished surface. A polishing pad characterized in that the polyurethane resin contains at least one of fatty acid metal salt particles having 8 to 24 carbon atoms, alkyl sulfosuccinate metal salt particles, or alkyl sulfate metal salt particles.

2. The polishing pad according to claim 1, characterized in that the metal constituting the fatty acid metal salt particles, alkyl sulfosuccinate metal salt particles, or alkyl sulfate metal salt particles having 8 to 24 carbon atoms is calcium or magnesium.

3. The polishing pad according to claim 1 or claim 2, characterized in that the metal constituting the above-mentioned fatty acid metal salt particles having 8 to 24 carbon atoms, alkyl sulfosuccinate metal salt particles, or alkyl sulfate metal salt particles is contained in the polishing pad at a concentration of 50 to 200 ppm.

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