Polishing pad

Abstract

To provide a polishing pad which has excellent step dissolution performance and excellent abrasion resistance while suppressing occurrence of scratches.SOLUTION: A polishing pad has a polishing layer composed of a polyurethane resin foam containing an isocyanate-terminated prepolymer, and a curing agent, wherein a numeric value obtained from the following expression (1) using content weight ratios of an amorphous phase and a crystalline phase in the polishing layer measured at 40°C and 80°C by a pulse NMR method is 0.70 to 1.30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polishing pad. The polishing pad of the present invention is used for polishing optical materials, semiconductor devices, glass substrates for hard disks, etc., and is particularly suitable for polishing devices having an oxide layer, metal layer, etc. formed on a semiconductor wafer. [Background technology]

[0002] Chemical mechanical polishing (CMP) is a commonly used polishing method for planarizing the surfaces of optical materials, semiconductor wafers, semiconductor devices, and hard disk substrates. The CMP method will be described with reference to FIG. 1. As shown in FIG. 1, a polishing apparatus 1 for performing the CMP method is equipped with a polishing pad 3. The polishing pad 3 contacts the workpiece 8 held by a holding platen 16 and a retainer ring (not shown in FIG. 1) that prevents the workpiece 8 from shifting. The polishing pad 3 includes a polishing layer 4, which is the layer that performs the polishing, and a cushion layer 6 that supports the polishing layer 4. The polishing pad 3 is rotated while pressed against the workpiece 8, polishing the workpiece 8. During this process, a slurry 9 is supplied between the polishing pad 3 and the workpiece 8. The slurry 9 is a mixture (dispersion liquid) of water, various chemical components, and hard, fine abrasive grains. As the chemical components and abrasive grains flow, the relative movement with the workpiece 8 increases the polishing effect. The slurry 9 is supplied to and discharged from the polishing surface via grooves or holes.

[0003] The polishing layer material used in polishing semiconductor devices is a hard polyurethane material obtained by reacting a prepolymer containing an isocyanate component (e.g., toluene diisocyanate (TDI)) and a high molecular weight polyol (e.g., polyoxytetramethylene glycol (PTMG)) with a diamine curing agent (e.g., 4,4'-methylenebis(2-chloroaniline) (MOCA)). This hard polyurethane material is composed of a soft segment formed from the high molecular weight polyol and a hard segment formed from urethane bonds or urea bonds. In recent years, with the miniaturization of wiring in semiconductor devices, conventional polishing layers or polishing pads have sometimes been found to be insufficient in terms of step-elimination performance, and further investigation is being conducted.

[0004] Patent Document 1 discloses a polishing pad that uses a polishing layer with a crystalline phase (S phase) content of more than 70% as measured by pulse NMR, which reduces changes in hardness due to heat, resulting in sufficient polishing and less scratches, allowing for stable polishing.

[0005] However, after examining Patent Document 1, it was found that scratches are likely to occur simply under the condition that the crystalline phase exceeds 70% at room temperature. This is because if foreign matter is mixed in during polishing, the foreign matter can cause a temperature rise, which can change the proportions of the crystalline, intermediate, and amorphous phases.

[0006] Furthermore, from the standpoint of durability, a hard polishing pad is preferable, but if it is too hard, it will not have the properties to eliminate unevenness present in the workpiece being polished (step-eliminating performance), and the problem will arise that the steps will not be eliminated even if polishing is continued. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Restatement 2016 / 158348 publication Summary of the Invention [Problem to be solved by the invention]

[0008] The inventors have investigated the proportions of the crystalline phase, mesophase, and amorphous phase in the polishing layer, and have found that the above-mentioned problems can be solved when the value obtained by a predetermined formula using the weight percentage of the amorphous phase at 40°C and the weight percentage of the amorphous phase at 80°C falls within a predetermined range, thereby achieving the present invention. [Means for solving the problem]

[0009] [1] A polishing pad having a polishing layer made of a polyurethane resin foam containing an isocyanate-terminated prepolymer and a curing agent, The following formula (1) is used to calculate the weight ratio of the amorphous phase and the crystalline phase in the polishing layer measured at 40°C and 80°C by pulse NMR:

number

[0010] The polishing pad of the present invention has excellent step-eliminating performance and excellent wear resistance. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing the state of polishing. [Figure 2] FIG. 2 is a cross-sectional view of a polishing pad. [Figure 3] FIG. 3 is a diagram illustrating the step-eliminating performance. [Figure 4] FIG. 4 shows the tan σ results obtained in Example 3. [Figure 5] FIG. 5 shows the results of tan σ obtained in Comparative Example 1. [Figure 6] FIG. 6 is a graph showing the step-eliminating performance of the examples and comparative examples (when using a polished object in which the wiring has an insulating film width of 100 μm for a Cu wiring width of 100 μm). [Figure 7] FIG. 7 is a graph showing the step-eliminating performance of the examples and comparative examples (when using a polished object in which the wiring has an insulating film width of 50 μm against a Cu wiring width of 50 μm). DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the embodiments of the invention will be described, but the present invention is not limited to the embodiments of the invention.

[0013] <<Polishing pads>> The structure of the polishing pad 3 will be described with reference to Fig. 2. As shown in Fig. 2, the polishing pad 3 includes a polishing layer 4 and a cushion layer 6. The shape of the polishing pad 3 is preferably disk-shaped, but is not particularly limited thereto, and the size (diameter) can also be determined appropriately depending on the size of the polishing apparatus 1 equipped with the polishing pad 3, and can be, for example, about 10 cm to 2 m in diameter. In the polishing pad 3 of the present invention, the polishing layer 4 is preferably bonded to the cushion layer 6 via an adhesive layer 7, as shown in FIG. The polishing pad 3 is attached to the polishing platen 10 of the polishing apparatus 1 by double-sided tape or the like arranged on the cushion layer 6. The polishing pad 3 is rotated by the polishing apparatus 1 while pressing against the object 8 to be polished, and polishes the object 8 to be polished.

[0014] <Polishing layer> (composition) The polishing pad 3 includes a polishing layer 4 that is a layer for polishing an object to be polished 8. The material that constitutes the polishing layer 4 is a polyurethane resin foam. The material, manufacturing method, etc. of the polyurethane resin foam will be described later. The size (diameter) of the polishing layer 4 is the same as that of the polishing pad 3, and can be about 10 cm to 2 mm in diameter, and the thickness of the polishing layer 4 can usually be about 1 to 5 mm. The polishing layer 4 is rotated together with the polishing table 10 of the polishing device 1, and while a slurry 9 is poured onto it, the chemical components and abrasive grains contained in the slurry 9 are moved relative to the object 8 to be polished, thereby polishing the object 8 to be polished. Hollow microspheres 4A (foam) are dispersed in the polishing layer 4. The polishing layer 4 is dry molded.

[0015] (Groove machining) It is preferable to provide grooves, if necessary, on the surface of the polishing layer 4 of the present invention facing the polished object 8. The grooves are not particularly limited and may be either slurry discharge grooves that communicate with the periphery of the polishing layer 4 or slurry retention grooves that do not communicate with the periphery of the polishing layer 4, or both slurry discharge grooves and slurry retention grooves. Examples of the slurry discharge grooves include lattice grooves and radial grooves, while examples of the slurry retention grooves include concentric grooves and perforations (through holes), and these can also be combined.

[0016] (Shore D hardness) The Shore D hardness of the polishing layer 4 of the present invention is not particularly limited, but is, for example, 20 to 100, preferably 30 to 80, and more preferably 40 to 70. If the Shore D hardness is low, it becomes difficult to flatten fine irregularities by low-pressure polishing. In addition, it may affect edge sagging. If the Shore D hardness is too high, it may be rubbed strongly against the polished object 8, causing scratches on the polished surface of the polished object 8.

[0017] In the polishing pad 3 of the present invention, hollow microspheres 4A are used to encapsulate air bubbles within the polyurethane resin molding. Hollow microspheres refer to microspheres with voids. The shapes of the hollow microspheres 4A include spherical, elliptical, and shapes similar thereto. Examples include pre-expanded microspheres and those obtained by thermally expanding unexpanded thermally expandable microspheres.

[0018] (crystalline phase, mesophase, amorphous phase) In the polishing layer of the polishing pad of the present invention, the value obtained by formula (1) using the weight percentage of the amorphous phase measured at 40°C (NC40), the weight percentage of the amorphous phase measured at 80°C (NC80), the weight percentage of the crystalline phase measured at 40°C (CC40), and the weight percentage of the crystalline phase measured at 80°C (CC80) is 0.70 to 1.30.

[0019]

number

[0020] The meaning of formula (1) is that when the ratio of the amorphous phase to the crystalline phase is calculated at 40°C and 80°C, the ratio at 80°C is greater than the ratio at 40°C, and the magnitude satisfies 0.70 to 1.30.

[0021] Polishing is performed at about 40°C, but as polishing progresses, the temperature of the polishing pad may rise to about 80°C due to friction. If the value of formula (1) is less than 0.7 or more than 1.30, the balance between the amorphous phase and the crystalline phase deteriorates with temperature changes, resulting in poor step-eliminating performance and poor wear resistance.

[0022] The lower limit of the value obtained by the above formula (1) is preferably 0.80 or more, more preferably 0.90 or more. The upper limit of the value obtained by the above formula (1) is preferably 1.29 or less, more preferably 1.28 or less.

[0023] The NC40 content in the polishing layer is preferably 10 to 20% by weight, which is preferable because the polishing pad has an appropriate hardness and improves the step-eliminating performance. The polishing layer preferably contains 25 to 35% by weight of NC80. When the NC80 content is 25 to 35% by weight, the soft segment contains a certain amount of amorphous phase, resulting in excellent step-eliminating performance and wear resistance.

[0024] In the present invention, the proportions of the crystalline phase, mesophase, and amorphous phase of the polishing layer are measured by pulsed NMR. In pulsed NMR measurement, the foamed polyurethane is divided into a phase (short phase) (S phase) with a spin-spin relaxation time of less than 0.03 ms, a phase (middle phase) (M phase) with a spin-spin relaxation time of 0.03 ms or more but less than 0.2 ms, and a phase (long phase) (L phase) with a spin-spin relaxation time of 0.2 ms or more, and the weight content of each phase is determined. Regarding the content ratios of the S phase, M phase, and L phase, for example, the crystalline phase is mainly observed as the S phase in pulsed NMR measurement, the amorphous phase is mainly observed as the L phase, and the mesophase is mainly observed as the M phase in pulsed NMR measurement. Furthermore, the hard segment portion is mainly observed as the S phase in pulsed NMR measurement, and the soft segment portion is mainly observed as the L phase. The spin-spin relaxation time can be determined, for example, by carrying out measurements using a JEOL "JNM-MU25" by the Solid Echo method.

[0025] <tanδ> When the polishing layer of the present invention is subjected to a dynamic viscoelasticity test in a tensile mode at a frequency of 10 rad / sec and a temperature of 20 to 100°C, it is preferable that the difference between the maximum value (tanδmax) and the minimum value (tanδmin) of tanδ, which is the ratio of the storage modulus E' to the loss modulus E'', in the range of 40 to 80°C is 0.030 or less.

[0026] Tan δ is the ratio (E'' / E') of E'' (loss modulus) to E' (storage modulus). When the temperature of the polishing layer rises due to thermal energy such as polishing heat, the proportion of amorphous phase in the polishing layer increases, and E'' (loss modulus) is expected to increase relative to E' (storage modulus). In this case, the value of tan δ is expected to increase. However, the tan δ of the polishing layer used in the polishing pad of the present invention tends to decrease slightly as the temperature rises from 40 to 80°C (see, for example, Figure 4). The rate of decrease is very small, and the difference between the maximum value (tan δmax) and the minimum value (tan δmin) of tan δ at 40 to 80°C is 0.030 or less. If the difference between the maximum value (tan δmax) and the minimum value (tan δmin) is 0.030 or less over the range from 40 to 80°C, excellent step elimination performance tends to be maintained even at polishing temperatures such as 80°C.

[0027] Tan δ is measured by dynamic mechanical analysis (DMA) of the polishing layer in tension mode. DMA is a method for measuring the mechanical properties of a sample by applying time-varying (oscillating) strain or stress to the sample and measuring the resulting stress or strain. Measurement in tension mode evaluates the lateral movement of the polished object, thereby providing insight into the step-eliminating performance.

[0028] <Cushion layer> (composition) The polishing pad 3 of the present invention has a cushion layer 6. The cushion layer 6 desirably allows the polishing layer 4 to contact the workpiece 8 more uniformly. Materials for the cushion layer 6 include resins; impregnated materials in which the resins are impregnated into a base material; flexible materials such as synthetic resins and rubbers; and sponge materials using the resins. Examples of the resins include resins such as polyurethane, polyethylene, polybutadiene, and silicone, and rubbers such as natural rubber, nitrile rubber, and polyurethane rubber.

[0029] The cushion layer 6 may be a foam having a cellular structure. As the cellular structure, in addition to a nonwoven fabric or the like having voids formed therein, a suede-like material having teardrop-shaped bubbles formed by a wet film-forming method, or a sponge-like material having fine bubbles formed therein may be preferably used. Among these, if a cushion layer is made of a nonwoven fabric impregnated with polyurethane or a sponge-like material, it will be compatible with the polishing layer, and will be able to achieve a high polishing rate while maintaining the ability to eliminate unevenness.

[0030] <Adhesive layer> The adhesive layer 7 is a layer for adhering the cushion layer 6 and the polishing layer 4, and is usually made of a double-sided tape or an adhesive. Any double-sided tape or adhesive known in the art (e.g., an adhesive sheet) can be used. The polishing layer 4 and the cushion layer 6 are bonded together by an adhesive layer 7. The adhesive layer 7 can be formed of at least one adhesive selected from, for example, acrylic, epoxy, and urethane adhesives. For example, an acrylic adhesive is used, and the thickness can be set to 0.1 mm.

[0031] The polishing pad of the present invention has excellent step-eliminating performance and wear resistance. Here, step-eliminating performance refers to the time it takes for a patterned wafer with unevenness (concave and convex) to eliminate the step during polishing. Figure 3 shows a schematic diagram of the experiment to measure step-eliminating performance. When a 3500 Å step is present on the workpiece, the results show the elimination of the step when a polishing pad with high step-eliminating performance (dotted line) is used, compared with a polishing pad with relatively poor step-eliminating performance (solid line). While there is no significant difference at the time of (a) in Figure 3, as polishing progresses and the removal amount reaches 2000 Å, the polishing pad with good step-eliminating performance (dotted line) shows that it takes less time to eliminate the step than the polishing pad with relatively poor step-eliminating performance (solid line) ((b)). The polishing pad with high step-eliminating performance eliminates the step relatively quickly ((c)). It can be said that the polishing pad indicated by the dotted line has relatively better step-eliminating performance than the polishing pad indicated by the solid line.

[0032] The abrasion resistance refers to the resistance of the polishing layer (polishing pad) to abrasion.

[0033] <<Polishing pad manufacturing method>> A method for producing the polishing pad 3 of the present invention will be described.

[0034] <Abrasive layer material> A polyurethane resin foam is used as the material for the polishing layer 4. Specific examples of the main component include a material obtained by reacting an isocyanate-terminated prepolymer with a curing agent. To foam the material, a foaming agent is added to the material.

[0035] The method for producing the polishing layer 4 will be described below using an example in which an isocyanate-terminated prepolymer and a curing agent are used.

[0036] Examples of methods for producing the polishing layer 4 using an isocyanate-terminated prepolymer and a curing agent include a material preparation step of preparing at least an isocyanate-terminated prepolymer, an additive, and a curing agent; a mixing step of mixing at least the isocyanate-terminated prepolymer, the additive, and the curing agent to obtain a mixture for molding a molded body; and a curing step of molding the polishing layer 4 from the mixture for molding a molded body.

[0037] The material preparation process, the mixing process, and the molding process will be explained below.

[0038] <Material preparation process> To manufacture the polishing layer 4 of the present invention, an isocyanate-terminated prepolymer and a curing agent are prepared as raw materials for the polyurethane resin foam. Here, the isocyanate-terminated prepolymer is a urethane prepolymer for forming the polyurethane resin foam.

[0039] Each component will be described below.

[0040] (Isocyanate-terminated prepolymer) The isocyanate-terminated prepolymer is a compound obtained by reacting the following polyisocyanate compound with a polyol compound under commonly used conditions, and contains a urethane bond and an isocyanate group in the molecule. Furthermore, other components may be contained in the isocyanate-terminated prepolymer within the range that does not impair the effects of the present invention.

[0041] The isocyanate-terminated prepolymer may be a commercially available product, or may be one synthesized by reacting a polyisocyanate compound with a polyol compound. There are no particular limitations on the reaction, and the addition polymerization reaction may be carried out using a method and conditions known in the art for producing polyurethane resins. For example, the prepolymer may be produced by adding a polyisocyanate compound heated to 50°C to a polyol compound heated to 40°C while stirring in a nitrogen atmosphere, then heating the mixture to 80°C after 30 minutes and continuing the reaction at 80°C for 60 minutes. The isocyanate-terminated prepolymer preferably has an NCO equivalent of about 300 to 600. Therefore, when the isocyanate-terminated prepolymer is commercially available, it is preferable that the NCO equivalent falls within the above range, and when producing it by synthesis, it is preferable to adjust the NCO equivalent within the above range by using the following raw materials in appropriate proportions.

[0042] (Polyisocyanate compounds) In this specification, the term "polyisocyanate compound" refers to a compound having two or more isocyanate groups in the molecule. The polyisocyanate compound is not particularly limited as long as it has two or more isocyanate groups in the molecule. For example, diisocyanate compounds having two isocyanate groups in the molecule include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate (2,6-TDI), 2,4-tolylene diisocyanate (2,4-TDI), naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI), 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyl- Examples of the polyisocyanate compound include diphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p-phenylene diisothiocyanate, xylylene-1,4-diisothiocyanate, ethylidine diisothiocyanate, etc. These polyisocyanate compounds may be used alone, or multiple polyisocyanate compounds may be used in combination.

[0043] The polyisocyanate compound preferably contains 2,4-TDI and / or 2,6-TDI.

[0044] (Polyol compounds as raw materials for prepolymers) In this specification, the term "polyol compound" refers to a compound having two or more hydroxyl groups (OH) in the molecule. Examples of polyol compounds used in the synthesis of urethane bond-containing polyisocyanate compounds as prepolymers include diol compounds and triol compounds such as ethylene glycol, diethylene glycol (DEG), and butylene glycol; and polyether polyol compounds such as poly(oxytetramethylene) glycol (or polytetramethylene ether glycol) (PTMG), polypropylene glycol (PPG), and polyether polycarbonate diol (PEPCD). PEPCD is a compound represented by the following general formula:

[0045] [ka]

[0046] In the above formula, m and n represent the number of repeating units and each independently represents a real number. PEPCD can be used alone or in combination of two or more. Among these, PPG and PEPCD are preferred, and a combination of PPG and PEPCD is preferred. Among the above components, PPG and PEPCD are preferred, and a combination of PPG and PEPCD is preferred, from the viewpoint of facilitating adjustment of the above formula (1) to 0.70 to 1.30. The number average molecular weight (Mn) of the polyols such as PPG and PEPCD is not particularly limited, and is preferably, for example, 500 to 3000, and more preferably 800 to 2500. Here, the number average molecular weight can be measured by gel permeation chromatography (GPC). When measuring the number average molecular weight of the polyol compound from the polyurethane resin, each component can be decomposed by a conventional method such as amine decomposition, and then the number average molecular weight can be estimated by GPC.

[0047] (additives) As described above, additives such as an oxidizing agent can be added to the material of the polishing layer 4 as needed.

[0048] (hardening agent) In the method for producing the polishing layer 4 of the present invention, a curing agent (also called a chain extender) is mixed with the isocyanate-terminated prepolymer in the mixing step. By adding the curing agent, the main chain end of the isocyanate-terminated prepolymer bonds with the curing agent to form a polymer chain in the subsequent molding step, which then hardens. Examples of the curing agent include ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 4-methyl-2,6-bis(methylthio)-1,3-benzenediamine, 2-methyl-4,6-bis(methylthio)-1,3-benzenediamine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 2,2-bis[3-(isopropylamino)-4- polyamine compounds such as 2,2-bis[3-(1-methylpropylamino)-4-hydroxyphenyl]propane, 2,2-bis[3-(1-methylpentylamino)-4-hydroxyphenyl]propane, 2,2-bis(3,5-diamino-4-hydroxyphenyl)propane, 2,6-diamino-4-methylphenol, trimethylethylenebis-4-aminobenzoate, and polytetramethyleneoxide-di-p-aminobenzoate; ethylene glycol, propane, Pyrene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3- Examples of polyhydric alcohol compounds include methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, trimethylolpropane, trimethylolethane, trimethylolmethane, poly(oxytetramethylene) glycol, polyethylene glycol, and polypropylene glycol.Furthermore, the polyvalent amine compound may have a hydroxyl group, and examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc. As the polyvalent amine compound, a diamine compound is preferred, and it is more preferred to use, for example, 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (hereinafter abbreviated as MOCA).

[0049] When two or more polyols are used as raw materials for the prepolymer, the two or more polyols may be mixed and then reacted with a polyisocyanate compound, or two or more polyols may be reacted with a polyisocyanate compound, and then the mixture may be mixed and cured.

[0050] The polishing layer 4 can be formed by using a material to form hollow microspheres 4A, which have an outer shell and a hollow interior. The hollow microspheres 4A may be made of commercially available materials or may be synthesized by conventional methods. The material for the outer shell of the hollow microspheres 4A is not particularly limited, but examples include polyvinyl alcohol, polyvinylpyrrolidone, poly(meth)acrylic acid, polyacrylamide, polyethylene glycol, polyhydroxyether acrylate, maleic acid copolymer, polyethylene oxide, polyurethane, poly(meth)acrylonitrile, polyvinylidene chloride, polyvinyl chloride and organic silicone resins, and copolymers of two or more of the monomers constituting these resins (e.g., acrylonitrile-vinylidene chloride copolymer). Commercially available hollow microspheres include, but are not limited to, the Expancel series (trade name, manufactured by Akzo Nobel) and Matsumoto Microsphere (trade name, manufactured by Matsumoto Yushi Co., Ltd.). The gas contained in the hollow microspheres 4A is not particularly limited, but examples thereof include hydrocarbons, such as isobutane, pentane, and isopentane.

[0051] The shape of the hollow microspheres 4A is not particularly limited and may be, for example, spherical or nearly spherical. The average particle size of the hollow microspheres 4A is not particularly limited but is preferably 5 to 200 μm, more preferably 5 to 80 μm, even more preferably 5 to 50 μm, and particularly preferably 5 to 35 μm. The average particle size can be measured using a laser diffraction particle size analyzer (for example, Mastersizer 2000, manufactured by Spectris Co., Ltd.).

[0052] The material for the hollow microspheres 4A is added in an amount of preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass, and even more preferably 1 to 4 parts by mass, per 100 parts by mass of the isocyanate-terminated prepolymer.

[0053] In addition to the above components, conventional blowing agents may be used in combination with the hollow microspheres 4A within the range that does not impair the effects of the present invention, and a gas that is non-reactive with the above components may be blown into the hollow microspheres 4A during the mixing step described below. Examples of the blowing agent include water and blowing agents whose main component is a hydrocarbon having 5 or 6 carbon atoms. Examples of the hydrocarbon include linear hydrocarbons such as n-pentane and n-hexane, and alicyclic hydrocarbons such as cyclopentane and cyclohexane.

[0054] <Mixing process> In the mixing step, the isocyanate-terminated prepolymer obtained in the preparation step, the additives, and the curing agent are fed into a mixer and stirred and mixed. The mixing step is carried out in a state where the components are heated to a temperature that ensures the fluidity of each component.

[0055] <Forming process> In the molding process, the mixture for molding prepared in the mixing process is poured into a mold preheated to 30 to 100°C for primary curing, and then heated at about 100 to 150°C for about 10 minutes to 5 hours for secondary curing to form a cured polyurethane resin (polyurethane resin foam). At this time, the isocyanate-terminated prepolymer and the curing agent react to form a polyurethane resin, which cures the mixture. If the viscosity of the isocyanate-terminated prepolymer is too high, its fluidity will be poor, making it difficult to achieve uniform mixing. Increasing the temperature to lower the viscosity shortens the pot life and can result in uneven mixing, resulting in uneven sizes of hollow microspheres 4A in the resulting foam. Conversely, if the viscosity is too low, air bubbles will move within the mixture, making it difficult to form uniformly dispersed hollow microspheres 4A in the resulting foam. For this reason, it is preferable to set the viscosity of the prepolymer at a temperature of 50 to 80°C within the range of 500 to 10,000 mPa·s. This can be achieved, for example, by changing the molecular weight (degree of polymerization) of the prepolymer. The prepolymer is heated to approximately 50 to 80°C to become flowable.

[0056] In the molding process, the mixture is reacted in a mold as needed to form a foam. At this time, the prepolymer is crosslinked and hardened by the reaction between the prepolymer and the curing agent.

[0057] After obtaining the molded body, it is sliced ​​into sheets to form multiple polishing layers 4. A general slicing machine can be used for slicing. During slicing, the lower layer of the polishing layer 4 is held, and the polishing layer 4 is sliced ​​to a predetermined thickness starting from the upper layer. The slice thickness is set, for example, in the range of 0.8 to 2.5 mm. For example, in the case of a foam molded in a 50 mm thick mold, approximately 10 mm of the upper and lower layers of the foam are not used due to scratches, and 10 to 25 polishing layers 4 are formed from approximately 30 mm of the center. In the hardening and molding step, a foam is obtained in which hollow microspheres 4A are formed approximately uniformly inside.

[0058] The polishing surface of the resulting polishing layer 4 is grooved as needed. Grooves with any pitch, width, and depth can be formed by cutting the polishing surface with a required cutter. Examples of the slurry-retaining grooves include circular grooves formed in a concentric pattern, and examples of the slurry-discharging grooves include linear grooves formed in a lattice pattern or linear grooves formed radially from the center of the polishing layer.

[0059] After that, a double-sided tape is attached to the surface of the polishing layer 4 opposite to the polishing surface of the polishing layer 4. There are no particular restrictions on the double-sided tape, and any double-sided tape known in the art can be selected and used.

[0060] <Method of manufacturing cushion layer 6> As described above, examples of the material for the cushion layer 6 include an impregnated material in which resin fibers (nonwoven fabric, flexible film, etc.) such as polyethylene or polyester are impregnated with a resin solution such as urethane; a suede material using a resin material such as urethane; and a sponge material using a material such as urethane. In the present invention, a known material can be used for the cushion layer 6, and a known manufacturing method can also be used.

[0061] <Joining process> In the bonding step, the formed polishing layer 4 and cushion layer 6 are bonded together (bonded) with an adhesive layer 7. For example, an acrylic adhesive is used for the adhesive layer 7, and the adhesive layer 7 is formed to a thickness of 0.1 mm. That is, the acrylic adhesive is applied to a substantially uniform thickness on the surface of the polishing layer 4 opposite the polishing surface. The surface of the polishing layer 4 opposite the polishing surface P and the surface of the cushion layer 6 (the surface on which the skin layer is formed) are pressed together via the applied adhesive, and the polishing layer 4 and cushion layer 6 are bonded together with the adhesive layer 7. Then, after cutting into a desired shape such as a circle, an inspection is performed to check for the absence of dirt or foreign matter, etc., and the polishing pad 3 is completed. [Example]

[0062] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0063] In each example and comparative example, unless otherwise specified, "parts" means "parts by mass."

[0064] The NCO equivalent is a numerical value showing the molecular weight of the prepolymer (PP) per NCO group, which is calculated by the formula "(mass (parts) of the polyisocyanate compound + mass (parts) of the polyol compound) / [(number of functional groups per molecule of the polyisocyanate compound × mass (parts) of the polyisocyanate compound / molecular weight of the polyisocyanate compound) - (number of functional groups per molecule of the polyol compound × mass (parts) of the polyol compound / molecular weight of the polyol compound)]".

[0065] (About the polishing layer) Isocyanate-terminated prepolymers 1 and 2 were prepared by reacting 2,4-tolylene diisocyanate (TDI) as an isocyanate compound with PPG and PEPCD as polyol compounds (see Table 1 for the components used in preparing the urethane prepolymers). 2.7 parts of pre-expanded hollow microspheres, each of which had an acrylonitrile-vinylidene chloride copolymer shell and contained isobutane gas, were added to 100 parts of the isocyanate-terminated prepolymer prepared in the proportions shown in Table 2 and mixed to obtain a mixed solution. The resulting mixed solution was placed in a first liquid tank and maintained at 60°C. Next, 23.5 parts of MOCA as a curing agent, separate from the first liquid, was placed in a second liquid tank, heated to 120°C, melted, and maintained at that temperature. The liquids from the first and second liquid tanks were injected into a mixer equipped with two injection ports so that the R value, which represents the equivalent ratio of amino groups and hydroxyl groups present in the curing agent to the terminal isocyanate groups in the prepolymer, was 0.9. The two injected liquids were mixed and stirred while being poured into a preheated mold of a molding machine, then the mold was clamped and heated at 80°C for 30 minutes to perform primary curing. The primary cured molded product was then demolded and subjected to secondary curing in an oven at 120°C for 4 hours to obtain a urethane molded product. The obtained urethane molded product was allowed to cool to 25°C and then heated again in an oven at 120°C for 5 hours before being sliced ​​to a thickness of 1.3 mm to obtain polishing layers 1 to 5 shown in Table 2. The density and Shore D hardness of each polishing layer are shown in Table 3, and the proportions of the crystalline phase, intermediate layer, and amorphous phase are shown in Table 4. The measurement method and conditions for pulse NMR measurement are as follows.

[0066] (density) Density of the polishing layer (g / cm 3 ) was measured in accordance with the Japanese Industrial Standard (JIS K 6505). (Shore D hardness) The Shore D hardness of the polishing layer was measured using a D-type hardness tester in accordance with the Japanese Industrial Standard (JIS-K-6253). Here, the measurement sample was obtained by stacking multiple polishing layers as necessary to achieve a total thickness of at least 4.5 mm.

[0067] (Pulse NMR measurement) Equipment Bruker Minispec mq20 (20MHz) Repeat time: 4 seconds Measurement method Solid echo method Accumulation count: 16 Measurement temperature 40℃, 80℃

[0068] [Table 1]

[0069] [Table 2]

[0070] [Table 3]

[0071] [Table 4]

[0072] (Dynamic viscoelasticity measurement (tanδ)) DMA (dynamic viscoelasticity measurement) was performed on the polishing layers 1 to 5. Dry samples were obtained by holding them for 40 hours in a thermo-hygrostat chamber set at a temperature of 23°C (21 to 25°C) and a relative humidity of 50% (45 to 55%). Measurements were performed in tension mode under normal atmospheric conditions (dry conditions). Other conditions were as follows. The ratio (E" / E') of the obtained E" (loss modulus) and E' (storage modulus) was calculated to determine tan δ. The results of Example 3 are shown in Figure 4, and the results of Comparative Example 1 are shown in Figure 5. The maximum and minimum values ​​of each data point, as well as the difference between them, are summarized in Table 5. Device: RSA-G2 (TA Instruments) Sample size: 5cm long x 0.5cm wide x 0.125cm thick Test mode: Tensile mode Frequency: 10 rad / sec (1.6 Hz) Measurement temperature: 20~100℃ Distortion range: 0.10% Test length: 1cm Heating rate: 5.0℃ / min Initial load: 148g Measurement interval: 2 points / ℃

[0073] [Table 5]

[0074] (About the cushion layer) A nonwoven fabric made of polyester fibers with a density of 0.15 g / cm3 was immersed in a resin solution (DMF solvent) containing a urethane resin (manufactured by DIC Corporation, product name "C1367"). After immersion, the resin solution was squeezed out of the nonwoven fabric using a mangle roller capable of applying pressure between a pair of rollers, allowing the nonwoven fabric to be substantially uniformly impregnated with the resin solution. The nonwoven fabric impregnated with the resin solution was then immersed in a coagulation solution consisting of water at room temperature to wet-coagulate the resin, yielding a resin-impregnated nonwoven fabric. The resin-impregnated nonwoven fabric was then removed from the coagulation solution and further washed with a washing solution consisting of water to remove N,N-dimethylformamide (DMF) from the resin, followed by drying. After drying, the skin layer on the surface of the resin-impregnated nonwoven fabric was removed by buffing, yielding a 1.3 mm-thick cushion layer made of resin-impregnated nonwoven fabric.

[0075] Examples and Comparative Examples The polishing layers 1 to 5 and the cushion layer were joined with 0.1 mm thick double-sided tape (a PET substrate with adhesive layers made of acrylic resin on both sides), and double-sided tape was attached to the opposite sides of the cushion layer and adhesive layer to produce the polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2.

[0076] (wear test) The resulting polishing pad was subjected to a wear test using a small friction and wear tester under the following conditions. After the wear test, the thickness (amount of wear) of the polishing layer was measured. The results are shown in Table 6.

[0077] (Wear test conditions) Polishing machine used: Small friction and wear tester Indenter side: PAD (17φ) Plate side: #180 sandpaper Load: 300g Liquid: water Flow rate: 45ml / min Plate rotation speed: 40 rpm Time: 10 minutes Thickness measurement load: 300g

[0078] [Table 6]

[0079] Increasing the PPG content in the prepolymer increases the amount of wear and worsens the wear resistance. It was found that when the PPG content is low, the increase in the amount of wear is suppressed.

[0080] (Step-eliminating performance test) The polishing pads of the examples and comparative examples were placed in the designated positions of a polishing machine using double-sided tape with an acrylic adhesive, and polishing was performed under the following polishing conditions. The step-elimination performance was evaluated by measuring 100 μm / 100 μm dishing using a step / surface roughness / microprofile measuring device (P-16+, manufactured by KLA Tencor Corporation). The evaluation results are shown in Figure 6. A patterned wafer with a film thickness of 7000 angstroms and a step height of 3000 angstroms was polished by adjusting the polishing rate so that the amount of polishing per step was 1000 angstroms. The polishing was performed in stages, and the wafer step height was measured each time. The step height on the vertical axis represents the step height. In Figure 6, 100 / 100 indicates a wiring with a Cu wiring width of 100 μm and an insulating film width of 100 μm, and in Figure 7, 50 / 50 indicates a wiring with a Cu wiring width of 50 μm and an insulating film width of 50 μm.The smaller the number, the finer the wiring.

[0081] (polishing conditions) Polishing machine used: F-REX300X (manufactured by Ebara Corporation) Disk: A188 (3M) Polishing agent temperature: 20℃ Polishing platen rotation speed: 90 rpm Polishing head rotation speed: 81 rpm Grinding pressure: 3.5psi Polishing slurry: CSL-9044C (a mixture of CSL-9044C stock solution and purified water at a weight ratio of 1:9) (manufactured by Fujifilm Planar Solutions) Polishing slurry flow rate: 200 ml / min Polishing time: 60 seconds Polished object: the above-mentioned patterned wafer Pad break: 32N 10 minutes Conditioning: In-situ 18N 16 scans, Ex-situ 32N 4 scans

[0082] 6, it was found that the polishing pads of Examples 1 to 3 were equivalent to the polishing pad of Comparative Example 1 and had superior step-eliminating performance compared to the polishing pad of Comparative Example 2. [Industrial Applicability]

[0083] The present invention contributes to the manufacture and sale of polishing pads and has industrial applicability.

[0084] 1 Polishing equipment 3 polishing pads 4 Polishing layer 4A Hollow microspheres 6 Cushion layer 7 Adhesive layer 8 Object to be polished 9. Slurry 10 Polishing plate

Claims

1. A polishing pad having a polishing layer made of a polyurethane resin foam containing an isocyanate-terminated prepolymer and a curing agent, The following formula (1) is used to determine the weight ratio of the amorphous phase and the crystalline phase in the polishing layer measured at 40°C and 80°C by pulse NMR: [Equation 1] wherein the numerical value obtained from is 0.85 to 0.

96.

2. 2. The polishing pad according to claim 1, wherein the difference between the maximum and minimum values ​​of tan δ obtained by measuring the polishing layer in a dynamic viscoelasticity test at 40° C. to 80° C. is 0.030 or less.

3. 3. The polishing pad according to claim 1, wherein the NC40 is 10 to 20% by weight.

4. 4. The polishing pad according to claim 1, wherein the NC80 is 25 to 35% by weight.

5. The polishing pad of claim 1 , wherein the polishing layer comprises polypropylene glycol and polyether polycarbonate diol.

6. 6. The polishing pad of claim 5, wherein the ratio of the PEPCD to the total of the polypropylene glycol and the polyether polycarbonate diol is less than 80%.

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