Polishing pad

Abstract

The purpose of the present invention is to provide a polishing pad that excels in level difference elimination performance and flattening performance.　The polishing pad has a polishing layer comprising a polyurethane resin foam for which an isocyanate-terminated prepolymer and a curing agent are raw materials, and the polishing pad is characterized in that: the ratio of the content proportion of a crystalline phase and the content proportion of an amorphous phase in the polishing layer measured via a pulse NMR method in a wet state at 40°C is 0.5-1.0; and the ratio of the content proportion of an intermediate phase and the content proportion of the amorphous phase in the polishing layer measured via a pulse NMR method in a wet state at 40°C is 0.4-0.9.

Description

Polishing pad

[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.

[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 provided with a polishing pad 3. The polishing pad 3 contacts a 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 a layer that performs 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. A slurry 9 is supplied between the polishing pad 3 and the workpiece 8. The slurry 9 is a mixture (dispersion) of water, various chemical components, and hard, fine abrasive grains, and as the chemical components and abrasive grains flow, they move relative to the workpiece 8, thereby increasing the polishing effect. The slurry 9 is supplied to and discharged from the polishing surface through grooves or holes.

[0003] In polishing semiconductor devices, polishing pads are typically used whose polishing layer is made of 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-based curing agent (e.g., 4,4'-methylenebis(2-chloroaniline) (MOCA)). The high molecular weight polyol contained in the prepolymer forms a urethane soft segment, and PTMG, which exhibits ease of handling and moderate rubber elasticity, has traditionally been used as the high molecular weight polyol. However, in recent years, with the miniaturization of wiring in semiconductor devices, conventional polishing pads have sometimes been insufficient in terms of step removal and planarization performance when polishing workpieces containing a mixture of steps of different heights. As a result, the use of high molecular weight polyols other than PTMG has been investigated. Patent Document 1 discloses polishing pads that use a mixture of PPG and PTMG as the high molecular weight polyol in the prepolymer to reduce defect rates.

[0004] JP 2011-040737 A

[0005] However, the polishing pad described in Patent Document 1 uses a mixture of PPG and PTMG, and therefore does not have sufficient step-eliminating and planarizing performance. The present invention has been made in consideration of the above problems, and an object of the present invention is to provide a polishing pad that has excellent step-eliminating and planarizing performance.

[0006] The inventors have found a polishing pad with a polishing layer that has excellent step-eliminating performance and flattening performance when polishing an object that has a mixture of steps of different heights, by adjusting the ratio of the content of crystalline phase and the content of amorphous phase of the polishing layer, and the ratio of the content of intermediate phase and the content of amorphous phase, which are measured by pulse NMR in wet state, and have arrived at the present invention.Furthermore, the inventors have found that when changing from dry state to wet state, the content of intermediate phase of the polishing layer changes little, and the content of amorphous phase of the polishing layer increases.When the changes of the intermediate phase and the amorphous phase in the polishing layer are specific, a polishing pad that can solve the above-mentioned problem can be obtained, and have arrived at the present invention.That is, the present invention includes the following: [1] A polishing pad having a polishing layer made of a polyurethane resin foam made from an isocyanate-terminated prepolymer and a curing agent, wherein the ratio of the crystalline phase content (%) to the amorphous phase content (%) in the polishing layer measured at 40°C by pulse NMR in a wet state is 0.5 to 1.0, and the ratio of the mesophase content (%) to the amorphous phase content (%) in the polishing layer measured at 40°C by pulse NMR in a wet state is 0.4 to 0.9. [2] The polishing pad according to [1], wherein the amorphous phase content in the polishing layer measured at 40°C by pulse NMR in a wet state is 30.0% to 55.0%. [3] The polishing pad according to [1], wherein the mesophase content in the polishing layer measured at 40°C by pulse NMR in a wet state is 15.0% to 35.0%. [4] The polishing pad according to [1], wherein the isocyanate-terminated prepolymer contains a polyisocyanate compound-derived structural unit and a high-molecular-weight polyol-derived structural unit, and the high-molecular-weight polyol-derived structural unit contains at least a polyester diol-derived structural unit and a PTMG-derived structural unit. [5] The polishing pad according to [4], wherein the polyester diol used to form the polyester diol-derived structural unit has a number average molecular weight of 600 or more and 2,500 or less.[6] The polishing pad according to [4], wherein the PTMG-derived structural units account for 30% by weight or more and 80% by weight or less of the structural units derived from the high-molecular-weight polyol. [7] The polishing pad according to [4], wherein the polyurethane resin foam is made from at least two types of isocyanate-terminated prepolymers, at least one of which contains the PTMG-derived structural units, and the isocyanate-terminated prepolymer containing the PTMG-derived structural units has an NCO equivalent of 400 or more and 500 or less. [8] The polishing pad according to [4], wherein the polyurethane resin foam is made from at least two types of isocyanate-terminated prepolymers, at least one of which contains the polyester diol-derived structural units, and the isocyanate-terminated prepolymer containing the polyester diol structural units has an NCO equivalent of 550 or more and 700 or less. [9] A polishing pad having a polishing layer made of a polyurethane resin foam made from an isocyanate-terminated prepolymer and a curing agent, wherein the value obtained by subtracting the mesophase content (%) of the polishing layer measured at 40°C by pulse NMR in a dry state from the mesophase content (%) of the polishing layer measured at 40°C by pulse NMR in a wet state is -2.0% or more and 2.0% or less, and the value obtained by subtracting the amorphous phase content (%) of the polishing layer measured at 40°C by pulse NMR in a dry state from the amorphous phase content (%) of the polishing layer measured at 40°C by pulse NMR in a wet state is 2.0% or more and 5.7% or less.

[10] The polishing pad according to [9], wherein the crystalline phase content in the polishing layer measured at 40°C by pulse NMR in a wet state is smaller than the amorphous phase content.

[11] The polishing pad according to [9], wherein the content of amorphous phase in the polishing layer measured at 40°C by pulse NMR in the wet state is 30.0% or more and 55.0% or less.

[12] The polishing pad according to [9], wherein the content of amorphous phase in the polishing layer measured at 40°C by pulse NMR in the dry state is 30.0% or more and 50.0% or less.

[13] The polishing pad according to [9], wherein the isocyanate-terminated prepolymer contains a polyisocyanate compound-derived structural unit and a high-molecular-weight polyol-derived structural unit, and the high-molecular-weight polyol-derived structural unit contains a polyester diol-derived structural unit and a PTMG-derived structural unit.

[14] The polishing pad according to

[13] , wherein the polyester diol used to form the polyester diol-derived structural unit has a number-average molecular weight of 600 or more and 2,500 or less.

[15] The polishing pad according to

[13] , wherein the PTMG structural unit accounts for 30% by weight or more and 80% by weight or less of the high-molecular-weight polyol-derived structural unit.

[16] The polishing pad according to

[13] , wherein the polyurethane resin foam is made from at least two isocyanate-terminated prepolymers, at least one of the at least two isocyanate-terminated prepolymers contains the PTMG-derived structural unit, and the NCO equivalent of the isocyanate-terminated prepolymer containing the PTMG-derived structural unit is 400 or more and 500 or less.

[17] The polyurethane resin foam is made from at least two types of isocyanate-terminated prepolymers, at least one of the at least two types of isocyanate-terminated prepolymers contains the polyester diol-derived structural unit, and the NCO equivalent of the isocyanate-terminated prepolymer containing the polyester diol-derived structural unit is 550 or more and 700 or less.

[13] The polishing pad described in.

[0007] When the ratio of the content of the crystalline phase and the content of the amorphous phase of the polishing layer measured by the pulse NMR method in a wet state is adjusted to a specific range, the proportion of the amorphous phase with high mobility becomes larger than that of the crystalline phase or the intermediate phase, and the polishing layer is moderately softened during polishing, so that the polishing pad has excellent step elimination performance and planarization performance even on a polished object having a mixture of steps of different heights.Furthermore, when the state changes from dry to wet, the content of the intermediate phase of the polishing layer changes little, and the content of the amorphous phase of the polishing layer becomes larger than that of the crystalline phase or the intermediate phase, so that the polishing layer is moderately softened during polishing.A polishing pad with such a polishing layer is a polishing pad with excellent step elimination performance and planarization performance on a polished object having a mixture of steps of different heights.

[0008] Fig. 1 is a schematic diagram showing a polishing state, Fig. 2 is a cross-sectional view of a polishing pad, and Fig. 3 is a schematic diagram for explaining step elimination performance and flattening performance.

[0009] Hereinafter, the embodiments of the invention will be described, but the present invention is not limited to the embodiments of the invention.

[0010] <<Polishing Pad>> 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 disc-shaped, but is not particularly limited thereto. 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, approximately 10 cm to 2 m in diameter. Preferably, as shown in FIG. 2, the polishing pad 3 of the present invention has the polishing layer 4 bonded to the cushion layer 6 via an adhesive layer 7. The polishing pad 3 is attached to the polishing platen 10 of the polishing apparatus 1 by double-sided tape or the like disposed on the cushion layer 6. The polishing pad 3 is rotated by the polishing apparatus 1 while pressing against the workpiece 8, thereby polishing the workpiece 8.

[0011] <Polishing Layer> (Configuration) The polishing pad 3 includes a polishing layer 4, which is a layer for polishing the workpiece 8. The material constituting the polishing layer 4 is a polyurethane resin foam. The material and manufacturing method 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 approximately 10 cm to 2 m in diameter, and the thickness of the polishing layer 4 can be approximately 0.8 to 5 mm. The polishing layer 4 is rotated together with the polishing surface plate 10 of the polishing apparatus 1, and while a slurry 9 is poured onto the polishing layer 4, the chemical components and abrasive grains contained in the slurry 9 are moved relative to the workpiece 8, thereby polishing the workpiece 8. The polishing layer 4 may have hollow microspheres 4A (foam) dispersed therein or may not have hollow microspheres, but it is preferable that the hollow microspheres 4A be dispersed therein.

[0012] (Grooving) 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, and examples of the slurry retention grooves include concentric grooves and perforations (through holes), and these can also be combined.

[0013] (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 or more and 100 or less, preferably 30 or more and 80 or less, and more preferably 40 or more and 70 or less. If the Shore D hardness is low, it becomes difficult to flatten fine irregularities by low-pressure polishing. 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.

[0014] (Density) The density of the polishing layer 4 of the present invention is not particularly limited, but is, for example, 0.60 g / cm ３ 1.25g / cm or more ３ or less, preferably 0.65 g / cm ３ 1.15g / cm or more ３ When the density of the polishing layer 4 is within the above range, the hardness of the polishing layer 4 can be maintained, and good step-eliminating performance tends to be obtained.

[0015] In the polishing pad 3 of the present invention, when hollow microspheres 4A are used, air bubbles are encapsulated within the polyurethane resin molding by the hollow microspheres 4A. Hollow microspheres refer to microspheres having 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.

[0016] (Regarding step elimination performance and planarization performance) The polishing pad of the present invention is characterized by having excellent step elimination performance and planarization performance due to the presence of a specific polishing layer. The polishing pad 3 of the present invention has excellent step elimination performance. Here, step elimination performance refers to the ability to reduce steps on a patterned wafer that has steps (unevenness) due to polishing. A schematic diagram of an experiment to measure step elimination performance is shown in Figure 3. At the time of Figure 3(a), there are steps of different heights on the polished object 8. A polishing pad with high step elimination performance preferentially polishes the steps on the patterned wafer as polishing progresses, polishing to the same height as the non-wiring portion in a short time and eliminating the steps (Figure 3(b)). On the other hand, a polishing pad that takes a long time to eliminate the steps on the patterned wafer has low step elimination performance.

[0017] The present invention aims to improve the step elimination and planarization performance when polishing a workpiece having steps of different heights. This will be explained in more detail using FIG. 3. For example, the workpiece is composed of a substrate and a metal film thereon, and the metal film is polished using the polishing pad of the present invention. For example, as shown in FIG. 3, the workpiece 8 is composed of a substrate 81 and a metal film 82 formed on the substrate (note that FIG. 3 is a cross-sectional view of the workpiece 8). Before polishing, as shown in FIG. 3(a), the formed metal film 82 has a small thickness from the surface (highest position) 813 of the substrate 81, where the metal film formed directly above the wiring-free portion 811 of the substrate 81 is thin, while the metal film formed directly above the wiring portions 812 and 813 of the substrate 81 is thick, resulting in steps (82A, 82B). Furthermore, as the width of the wiring becomes narrower, the thickness of the metal film increases. That is, the height of the step 82B directly above the narrow wiring 813 is X, while the height of the step 82A directly above the wide wiring 812 is Y, where X is greater than Y. When polishing such an object to be polished 8, if polishing is performed with a polishing pad having excellent step elimination and planarization performance, as shown in FIG. 3B, the surface of the metal film 82 on the object to be polished 8 is polished flat regardless of the location of the non-wiring portion 811 and the wiring portions 812 and 813, as the wiring portion 812 is preferentially polished. The metal film 82 on the object to be polished 8 is then polished in a flat state. On the other hand, if polishing is performed with a polishing pad having poor step elimination performance, it takes a long time for the thickness of the metal film directly above the wiring portions 812 and 813 to become equal to the thickness of the metal film on the non-wiring portion 811. If polishing is performed with a polishing pad having poor planarization performance, not only the metal film directly above the wiring portion but also other portions are polished, resulting in an unflattened metal film. The step elimination performance is a performance that indicates the degree of planarization of steps (unevenness) on a patterned wafer that has steps due to polishing. Specifically, a patterned wafer with unevenness is polished, and the remaining steps on the wafer after polishing (the degree of planarization of the stepped portion) are evaluated. Furthermore, the planarization performance evaluates whether, after polishing, there is no step between the metal film in the non-wiring portion and the metal film in the wiring portion, and the surface is flat.

[0018] (Crystalline Phase, Mesophase, Amorphous Phase) The proportions of the crystalline phase, mesophase, and amorphous phase of the polishing layer are determined by pulse NMR measurement. In pulse NMR measurement, the free induction decay (FID) signal can be separated into three components by subtracting the component with the longest spin-spin relaxation time using the least squares method and waveform separation. More specifically, the initial value of the obtained FID signal is proportional to the number of protons in the measurement sample, and when the measurement sample contains three components, the FID signal appears as the sum of the response signals of the three components. On the other hand, since the components contained in the measurement sample have different mobilities, the decay rate of the response signal differs between the components, resulting in different spin-spin relaxation times. Therefore, the polyurethane resin foam can be separated into three components using the least squares method, and the polyurethane resin foam is classified into a short phase (S phase), a middle phase (M phase), and a long phase (L phase) in order of shortest spin-spin relaxation time, and the content ratio 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 pulse NMR measurement, the amorphous phase is mainly observed as the L phase, and the mesophase is mainly observed as the M phase in pulse NMR measurement. Furthermore, the hard segment portion is mainly observed as the S phase in pulse 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 performing measurement by the Solid Echo method using a "JNM-MU25" manufactured by JEOL.

[0019] During polishing, the temperature of the polishing pad reaches 40°C. If the polishing pad's hardness becomes too high due to an increase in the proportion of hard segments during polishing, scratches may easily occur, resulting in a decrease in defect reduction performance. On the other hand, an increase in the proportion of soft segments softens the polishing pad, which is undesirable because it reduces its step-eliminating and planarizing performance. Here, the crystalline phase is a component with low mobility that corresponds to the hard segment component, while the amorphous phase is a component with high mobility that corresponds to the soft segment component. The ratio of the hard segment component to the soft segment component affects the physical properties of the polishing pad, such as its hardness. Furthermore, pulse NMR measurements have traditionally been performed in a dry state. However, as described above, actual polishing is performed while supplying a slurry, which is a mixture of water, various chemical components, and hard, fine abrasive grains. Actual experimental results are described in the Examples section, but it was found that the results of pulse NMR measurements performed in a dry state differ from those performed in a wet state.

[0020] In this specification, measurement by pulse NMR in a wet state means immersing the polishing layer material in pure water for 24 hours, wiping off the pure water on the surface of the polishing layer with Kimtowel (registered trademark), and performing pulse NMR measurement at a predetermined temperature (40°C in this invention).

[0021] In the polishing layer of the polishing pad of the first embodiment, the ratio of the content of the crystalline phase to the content of the amorphous phase measured at 40 ° C. by pulse NMR in a wet state is 0.5 or more and 1.0 or less. The ratio of the content of the crystalline phase to the content of the amorphous phase is preferably 0.55 or more and 0.95 or less, more preferably 0.60 or more and 0.90 or less, and even more preferably 0.55 or more and 0.85 or less. Furthermore, the ratio of the content of the mesophase to the content of the amorphous phase measured at 40 ° C. by pulse NMR in a wet state is 0.4 or more and 0.9 or less. The ratio of the content of the mesophase to the content of the amorphous phase is preferably 0.45 or more and 0.85 or less, more preferably 0.50 or more and 0.80 or less. By ensuring that the ratio of the crystalline phase content to the amorphous phase content in the polishing layer, as measured at 40°C by pulse NMR in a wet state, and the ratio of the intermediate phase content to the amorphous phase content, each satisfy the above ranges, the proportion of the amorphous phase, which has high mobility during polishing, becomes higher than that of the crystalline phase and the intermediate phase, and the polishing layer softens appropriately during polishing, thereby enabling the production of a polishing pad with excellent step elimination and planarization performance.

[0022] In the polishing layer of the polishing pad of the first embodiment, the content of amorphous phase in the polishing layer measured by pulse NMR in a wet state at 40 ° C. is preferably 30.0% or more and 55.0% or less, more preferably 32.0% or more and 50.0% or less, and even more preferably 35.0% or more and 50.0% or less. By satisfying the above range, the proportion of amorphous phase with high mobility is moderately present, and the polishing layer is moderately softened during polishing, so that the step elimination performance and flattening performance tend to be excellent.

[0023] In the polishing layer of the polishing pad of the first embodiment, the content of mesophase in the polishing layer measured at 40°C by pulse NMR in a wet state is preferably 15.0% or more and 35.0% or less, more preferably 17.0% or more and 33.0% or less, and even more preferably 20.0% or more and 30.0% or more.

[0024] In the polishing layer of the polishing pad of the first embodiment, the content of the crystalline phase in the polishing layer measured by pulse NMR in a wet state at 40 ° C. is 25.0% or more and 45.0% or less, preferably 28.0% or more and 42.0% or less, more preferably 28.0% or more and 35.0% or less. By satisfying the above range, the proportion of the crystalline phase with low mobility is moderately present, and the polishing layer has moderate hardness during polishing, so that the step elimination performance and flattening performance tend to be excellent.

[0025] In yet another embodiment, in the polishing layer of the polishing pad of the present invention, the mesophase content of the polishing layer measured in a wet state by pulse NMR at 40 ° C. minus the mesophase content of the polishing layer measured in a dry state by pulse NMR at 40 ° C. is -2.0% or more and 2.0% or less, preferably -1.5% or more and 1.8% or less, and more preferably -0.9% or more and 1.5% or less. Also, the amorphous phase content of the polishing layer measured in a wet state by pulse NMR at 40 ° C. minus the amorphous phase content of the polishing layer measured in a dry state by pulse NMR at 40 ° C. is 2.0% or more and 5.7% or less, preferably 2.5% or more and 5.6% or less, more preferably 3.0% or more and 5.6% or less, and even more preferably 4.0% or more and 5.5% or less. When the value obtained by subtracting the mesophase content of the polishing layer measured at 40°C by pulse NMR in a wet state from the mesophase content of the polishing layer measured at 40°C by pulse NMR in a dry state, and the value obtained by subtracting the amorphous phase content of the polishing layer measured at 40°C by pulse NMR in a wet state from the amorphous phase content of the polishing layer measured at 40°C by pulse NMR in a dry state, both satisfy the above ranges, the mesophase content of the polishing layer changes little when transitioning from a dry state to a wet state, the proportion of the amorphous phase, which has high mobility, increases moderately, and the polishing layer softens moderately during polishing, resulting in excellent step elimination and planarization performance.

[0026] In the polishing layer of the polishing pad of the second embodiment, it is preferable that the content of the crystalline phase in the polishing layer is smaller than the content of the amorphous phase when measured in a wet state by pulse NMR at 40° C. By satisfying the above range, the proportion of the amorphous phase with high mobility becomes larger than the proportion of the crystalline phase with low mobility, and the polishing layer is moderately softened during polishing, which tends to result in excellent step elimination performance and planarization performance.

[0027] In the polishing layer of the polishing pad of the second embodiment, the content of amorphous phase in the polishing layer measured by pulse NMR in a wet state at 40 ° C. is preferably 30.0% or more and 55.0% or less, more preferably 32.0% or more and 50.0% or less, and even more preferably 35.0% or more and 50.0% or less. By satisfying the above range, the proportion of amorphous phase with high mobility is moderately present, and the polishing layer is moderately softened during polishing, which tends to result in excellent step elimination performance and flattening performance.

[0028] Furthermore, in the polishing layer of the polishing pad of the second embodiment, the content of the amorphous phase in the polishing layer measured in a dry state by pulse NMR at 40 ° C. is preferably 30.0% or more and 50.0% or less, more preferably 32.0% or more and 48.0% or less, and even more preferably 34.0% or more and 45.0% or less. By satisfying the above range, it is possible to easily adjust the proportion of the amorphous phase in a wet state.

[0029] In the polishing layer of the second embodiment, the content of mesophase in the polishing layer measured at 40°C by pulse NMR in a wet state is preferably 15.0% or more and 35.0% or less, more preferably 17.0% or more and 33.0% or less, and even more preferably 20.0% or more and 30.0% or less.

[0030] In the polishing layer of the polishing pad of the second embodiment, the content of the crystalline phase in the polishing layer measured by pulse NMR method in wet state at 40 ° C is 25.0% or more and 45.0% or less, preferably 28.0% or more and 42.0% or less, more preferably 28.0% or more and 35.0% or less.By satisfying the above range, the proportion of the crystalline phase with low mobility is moderately present, and the polishing layer has moderate hardness during polishing, so that the step elimination performance and flattening performance tend to be excellent.

[0031] <Cushion Layer> (Configuration) 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 a base material is impregnated with resin; flexible materials such as synthetic resins and rubbers; and sponge materials using 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.

[0032] The cushion layer 6 may be a foam having a cellular structure. Examples of cellular structures that can be used include those with voids formed inside a nonwoven fabric, suede-like structures with teardrop-shaped bubbles formed by a wet film-forming method, and sponge-like structures with fine bubbles. Among these, nonwoven fabrics impregnated with polyurethane or sponge-like structures are preferred as cushion layers, as they are compatible with the polishing layer and can maintain excellent step-eliminating performance.

[0033] <Adhesive Layer> The adhesive layer 7 is a layer for adhering the cushion layer 6 and the polishing layer 4, and is typically composed of a double-sided tape or 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 the 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.

[0034] <<Method of Manufacturing Polishing Pad>> A method of manufacturing the polishing pad 3 of the present invention will be described.

[0035] <Polishing Layer Material> A polyurethane resin foam is used as the material for the polishing layer 4. Specific examples of the main component material 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.

[0036] 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.

[0037] 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 the isocyanate-terminated prepolymer and the curing agent; a mixing step of mixing at least the isocyanate-terminated prepolymer and the curing agent to obtain a mixture liquid for molding a molded body; and a molding step of molding the polishing layer 4 from the mixture liquid for molding a molded body.

[0038] The material preparation process, the mixing process, and the molding process will be explained below.

[0039] <Material Preparation Step> To manufacture the polishing layer 4 of the present invention, an isocyanate-terminated prepolymer, a curing agent, and hollow microspheres are prepared as raw materials for the polyurethane resin foam. Here, the isocyanate-terminated prepolymer is a urethane prepolymer (sometimes simply referred to as a prepolymer) for forming the polyurethane resin foam.

[0040] Each component will be described below.

[0041] (Isocyanate-Terminated Prepolymer) The isocyanate-terminated prepolymer can contain a polyisocyanate compound-derived structural unit and a polyol-derived structural unit, and is a compound obtained by reacting the following polyisocyanate compound with a polyol 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 a range that does not impair the effects of the present invention. From the viewpoints of adjusting physical properties and handling, two or more different types of isocyanate-terminated prepolymers can be used as the isocyanate-terminated prepolymer.

[0042] The isocyanate-terminated prepolymer may be a commercially available product, or may be one synthesized by reacting a polyisocyanate compound with a polyol. There are no particular limitations on the reaction, and an 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 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.

[0043] (Polyisocyanate Compound) 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-4,4'-biphenyl diisocyanate, 4,4 ... 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.

[0044] The polyisocyanate compound preferably contains 2,4-TDI and / or 2,6-TDI, and more preferably 2,4-TDI.

[0045] (Polyol as a Raw Material for Prepolymer) In this specification, a high molecular weight polyol means a compound having two or more hydroxyl groups (OH) in the molecule, and "high molecular weight" means a molecular weight of 500 or more. The polyol compound as a raw material for the prepolymer is not particularly limited as long as the object of the present invention can be achieved, and examples thereof include diol compounds, triol compounds, etc., such as ethylene glycol, diethylene glycol (DEG), and butylene glycol; polyether polyol compounds, such as poly(oxytetramethylene) glycol (or polytetramethylene ether glycol) (PTMG), polypropylene glycol (PPG), and polyether polycarbonate diol (PEPCD); and polyester polyols.

[0046] In the first embodiment, among the above components, in order to satisfy the polishing layer in which the ratio of the content of the crystalline phase to the content of the amorphous phase measured at 40 ° C. by pulse NMR in a wet state is 0.5 or more and 1.0 or less, and the ratio of the content of the mesophase to the content of the amorphous phase measured at 40 ° C. by pulse NMR in a wet state is 0.4 or more and 0.9 or less, it is preferable that the high molecular weight polyol-derived constitutional unit contains a polyoxytetramethylene glycol (PTMG)-derived constitutional unit and a polyester diol-derived constitutional unit. In a preferred embodiment, other polyol components may be used in addition to PTMG and polyester diol. In the second embodiment, among the above components, in order to satisfy the value obtained by subtracting the mesophase content of the polishing layer measured at 40°C by pulse NMR in a dry state from the mesophase content of the polishing layer measured at 40°C by pulse NMR in a wet state of -2.0% or more and 2.0% or less, and the value obtained by subtracting the amorphous phase content of the polishing layer measured at 40°C by pulse NMR in a dry state from the amorphous phase content of the polishing layer measured at 40°C by pulse NMR in a wet state of 2.0% or more and 5.7% or less, it is preferable that the high-molecular-weight polyol-derived constituent unit contains at least a polyoxytetramethylene glycol (PTMG)-derived constituent unit and a polyester diol-derived constituent unit. In a preferred embodiment, other polyol components may be used in addition to PTMG and polyester diol.

[0047] When a combination of polyoxytetramethylene glycol (PTMG) and polyester diol is used, the weight proportion of PTMG is preferably 30% by weight or more and 80% by weight or less based on the total weight of the high molecular weight polyol compound used as a raw material for the prepolymer.

[0048] The polyester diol is not particularly limited as long as it is a compound of an acid and a diol component, but examples thereof include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, and terephthalic acid. Examples of diols used in polyester diols include ethylene glycol, diethylene glycol (DEG), butylene glycol (1,4-butanediol), neopentyl glycol, 1,3-butanediol, 1,5-pentanediol, and 1,6-hexanediol. Among these, polyester diols synthesized from adipic acid and 1,4-butanediol are preferred, as they allow for easy adjustment of the ratio of crystalline phase to amorphous phase.

[0049] The number average molecular weight (Mn) of the polyester diol for forming the polyester diol-derived structural unit is preferably 600 or more and 2500 or less, more preferably 800 or more and 2000 or less. 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, it can also be estimated by GPC after decomposing each component by a conventional method such as amine decomposition. By having a number average molecular weight of 600 to 2500, the polishing pad can be given the necessary rubber elasticity, and the effects of the present invention tend to be obtained.

[0050] (NCO equivalent of isocyanate-terminated prepolymer) When two or more types of isocyanate-terminated prepolymers are used, the NCO equivalent of the isocyanate-terminated prepolymer is preferably 400 to 500, more preferably 420 to 490, for an isocyanate-terminated prepolymer containing a PTMG-derived structural unit, and is preferably 550 to 700, more preferably 570 to 660, for an isocyanate-terminated prepolymer forming a polyester diol-derived structural unit. Furthermore, when two or more types of isocyanate-terminated prepolymers are used, the NCO equivalent of the isocyanate-terminated prepolymer after mixing is preferably 400 to 650, more preferably 410 to 570. By satisfying the above ranges, excellent step elimination performance and planarization performance tend to be obtained. Therefore, when the isocyanate-terminated prepolymer is a commercially available product, it is preferable that the NCO equivalent satisfy the above range. When produced by synthesis, it is preferable to adjust the NCO equivalent within the above range by using the raw materials described below in appropriate proportions.

[0051] (Additives) As described above, additives such as an oxidizing agent can be added to the material of the polishing layer 4 as needed.

[0052] 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 and harden in the subsequent molding step.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- polyvalent amine 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-(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).

[0053] When two or more types of high molecular weight polyols are used as raw materials for the isocyanate-terminated prepolymer, the two or more types of high molecular weight polyols may be mixed and then reacted with a polyisocyanate compound, or two or more types of high molecular weight polyols may be reacted with a polyisocyanate compound, and then the mixture may be mixed and cured.

[0054] (Hollow Microspheres) The polishing layer 4 can be formed using 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 Nippon Phillite Co., Ltd.) 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.

[0055] 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 (e.g., Mastersizer 2000, manufactured by Spectris Co., Ltd.).

[0056] 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.

[0057] In addition to the above components, conventional blowing agents may be used in combination with the hollow microspheres 4A, provided that the effects of the present invention are not impaired. A gas unreactive with the 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 primarily composed of hydrocarbons having 5 or 6 carbon atoms. Examples of such hydrocarbons include linear hydrocarbons such as n-pentane and n-hexane, and alicyclic hydrocarbons such as cyclopentane and cyclohexane.

[0058] <Mixing step> 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.

[0059] <Molding Process> In the molding process, the mixture for molding prepared in the mixing process is poured into a mold preheated to 60-120°C and subjected to primary curing at 100-150°C for 30 minutes to 1 hour. The cured molded body is then removed from the mold and heated to approximately 100-150°C for 2-6 hours for secondary curing, resulting in a cured polyurethane resin (polyurethane resin foam). During this process, the urethane prepolymer and curing agent react to form a polyurethane resin, thereby curing the mixture. If the viscosity of the urethane prepolymer (isocyanate-terminated prepolymer) is too high, its fluidity deteriorates, making it difficult to achieve uniform mixing. Increasing the temperature to lower the viscosity shortens the pot life and, in turn, causes uneven mixing, resulting in variations in the size of hollow microspheres 4A formed in the resulting foam. Conversely, if the viscosity is too low, air bubbles 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 urethane prepolymer in the range of 500 to 10,000 mPa·s at a temperature of 50 to 80°C. This can be achieved, for example, by changing the molecular weight (degree of polymerization) of the urethane prepolymer. The urethane prepolymer is heated to about 50 to 80°C to make it flowable.

[0060] In the molding process, the mixture is reacted in a mold as needed to form a polyurethane resin foam, during which the urethane prepolymer reacts with the curing agent to crosslink and harden.

[0061] After obtaining the polyurethane resin foam, it is sliced ​​into sheets to form multiple polishing layers 4. A common slicer 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 polyurethane resin foam molded in a 50 mm thick mold, approximately 10 mm of the upper and lower layers of the polyurethane resin foam are not used due to scratches, and 10 to 25 polishing layers 4 are formed from approximately 30 mm of the center. This results in a polyurethane resin foam with hollow microspheres 4A formed approximately uniformly inside.

[0062] The polishing surface of the resulting polishing layer 4 is grooved as needed. By performing cutting or the like on the polishing surface using a required cutter, grooves with any pitch, width, and depth can be formed. Examples of the slurry retaining grooves include circular grooves formed in a concentric pattern, and examples of the slurry discharge grooves include linear grooves formed in a lattice pattern or linear grooves formed radially from the center of the polishing layer.

[0063] 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.

[0064] <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.

[0065] <Bonding Step> In the bonding step, the formed polishing layer 4 and cushion layer 6 are bonded (attached) 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 with the adhesive layer 7. Then, after cutting into a desired shape such as a circle, an inspection is performed to confirm that there is no dirt or foreign matter attached, and the polishing pad 3 is completed.

[0066] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0067] In each example and comparative example, unless otherwise specified, "parts" means "parts by mass."

[0068] 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) / [(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 × mass (parts) of the polyol / molecular weight of the polyol)]".

[0069] (Regarding the Polishing Layer) Two types of urethane prepolymers (PP1 and PP2) were prepared by reacting 2,4-tolylene diisocyanate (TDI) as an isocyanate compound; PTMG and diethylene glycol (DEG) or polyester polyol (a composite of adipic acid and 1,4-butanediol (adipic acid butylene glycol ester)); and diethylene glycol (DEG) as a polyol compound (see Table 1 for the components used in preparing the urethane prepolymers). 100 parts of a urethane prepolymer mixture mixed in the proportions shown in Table 2 were mixed with 1.8 parts of hollow microspheres (balloons: Expancel 920DU20 (manufactured by Nippon Phillite Co., Ltd.)) having an average particle size of 6.0 μm to obtain a mixed solution. The resulting mixed solution was placed in a first liquid tank and maintained at 60°C. Next, 26.2 parts of MOCA as a curing agent, separate from the first liquid, was placed in a second liquid tank, heated to 120°C, and melted and kept warm. The liquids from the first and second liquid tanks were each 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 injected two liquids were mixed and stirred while being poured into a mold preheated to 80°C, then clamped and heated at 80°C for 30 minutes to perform primary curing. The primary cured molded product was demolded and then 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, then heated again in an oven at 120°C for 5 hours, and sliced ​​to a thickness of 1.3 mm to obtain the polishing layer B used in Example 1 shown in Table 2. Polishing layers A, C, D and E were made by the same process according to Table 1 and Table 2.In addition, the density and Shore D hardness of each polishing layer are also shown in Table 2, and the content ratio of crystalline phase, intermediate phase and amorphous phase is shown in Table 3 (measured at 40 ° C in wet state and dry state, respectively).In addition, T (1), T (2) and T (3) in Table 3 are the relaxation times of crystalline phase, intermediate phase and amorphous phase, respectively, and their unit is msec (millisecond).In addition, from these data, predetermined values ​​are shown in Table 4.In addition, the measuring method and conditions of density, Shore D hardness and pulse NMR measurement (dry state and wet state) are as follows:

[0070] (Density) Density of the polishing layer (g / cm ３) was measured in accordance with Japanese Industrial Standards (JIS K 6505).

[0071] (Shore D hardness) The Shore D hardness of the polishing layer was measured using a Shore D hardness tester in accordance with the Japanese Industrial Standards (JIS-K-6253). Here, the measurement sample was obtained by stacking multiple polishing layers as necessary so that the total thickness was at least 4.5 mm.

[0072] (Pulse NMR measurement) Equipment: Bruker Minispec mq20 (20 MHz) Various １ H measurement T ２ Measurement method: Solid echo method, Acquisition Scale: 0.4 msec, Scan: 128 times, Recycle Delay: 0.5 sec, Measurement temperature: 40°C. After the device temperature reached the measurement temperature and the sample was set, it was left to stand for 5 minutes before starting the measurement. One measurement was taken immediately after the start of the measurement, and then one measurement was taken every 5 minutes thereafter, for a total of 6 measurements. Of the 6 measurements, the average value obtained by averaging the 5 measurements from the second to sixth measurements was used as the measurement result. The samples were prepared by punching out 8 mm diameter pieces from the polishing layers A to E, and storing them in a thermo-hygrostat chamber at a temperature of 23°C (±2°C) and a relative humidity of 50% (±5%) for 40 hours. Dry samples were also prepared by immersing them in pure water for 24 hours, after which the surface moisture was wiped off and measurements were immediately taken. The punched samples were filled into the sample tube to a height of 1 to 1.5 cm using the above-mentioned equipment and conditions.

[0073]

[0074]

[0075]

[0076]

[0077] (Regarding the cushion layer) A commercially available sponge-like urethane foam (Shore A hardness 60, density 0.55 g / cm ３The Shore A hardness of the cushion layer was determined in accordance with the Japanese Industrial Standards (JIS-K-7311) from the depth of penetration of an indenter pressed against the surface of the test piece via a spring. The density of the cushion layer was determined by measuring it in the same way as the polishing layer.

[0078] (Examples and Comparative Examples) The polishing layers A to E and the cushion layer were each bonded 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 side of the cushion layer opposite the adhesive layer to produce the polishing pads of Examples 1 to 3 and Comparative Examples 1 and 2.

[0079] (Polishing Performance Evaluation) A polishing test was carried out under the following polishing conditions using the polishing pads obtained in Examples 1 to 3 and Comparative Examples 1 and 2. The results are shown in Table 5.

[0080] (Polishing conditions) Polishing machine: F-REX300X (manufactured by Ebara Corporation) Disk: 34R (manufactured by KINIK) Retainer ring: Retainer ring GXKD (manufactured by Ebara Corporation) Rotation speed: (surface plate) 90 rpm, (polishing head) 81 rpm Polishing pressure: 1.7 psi Polishing agent temperature: 20°C Polishing agent discharge rate: 200 ml / min Polishing agent: CSL-9044C (a mixture of CSL-9044C stock solution and pure water at a weight ratio of 1:9 was used) (manufactured by Fujifilm Planar Solutions Co., Ltd.) Workpiece to be polished: Cu film substrate (disc-shaped, 300 mm diameter) Polishing time: 60 seconds Pad break: 32N 20 minutes Conditioning: Ex-situ 32N 4 scans

[0081] (Step Elimination Performance Evaluation Test) The polishing pad was installed in a predetermined position on the polishing device via a double-sided tape with an acrylic adhesive, and polished under the above-mentioned polishing conditions. The step elimination performance was evaluated by polishing a pattern wafer (workpiece) with no wiring, 0.18 μm / 0.18 μm, and 0.50 μm / 0.50 μm wiring widths, and measuring the remaining step height with an atomic force microscope (product name "NX-wafer", manufactured by Park Systems) in NC-AFM (non-contact) measurement mode, and measuring the thickness of the Cu film after polishing with a four-probe sheet resistance measurement device (manufactured by KLA Tencor Corporation, trade name "RS-200", measurement: DBS mode). More specifically, the step height of the pattern wafer (workpiece) before polishing was measured with an atomic force microscope and a four-probe sheet resistance measurement device. Before polishing, a patterned wafer (workpiece) having a Cu film with a height of 10,000 angstroms remaining in the non-wiring areas, a Cu film with a height of 21,000 angstroms remaining on the 0.18 μm / 0.18 μm wiring width, and a Cu film with a height of 14,000 angstroms remaining on the 0.50 μm / 0.50 μm wiring width was polished once, and the height of the Cu film remaining in each location was measured using an atomic force microscope and a four-probe sheet resistance measurement device. In Table 5, cases where the difference between the height of the step remaining in all wiring widths after polishing and the height remaining in the non-wiring areas after polishing was 1,000 angstroms or less was represented by ○, and cases where the difference between the height of the step remaining in all wiring widths after polishing and the height remaining in the non-wiring areas after polishing exceeded 1,000 angstroms were represented by ×.

[0082] (Planarization Performance Evaluation Test) The planarization reduction performance was evaluated by measuring the remaining heights of the patterned wafer (object to be polished) after polishing under the above polishing conditions at the locations where there were no wiring, 0.18 μm / 0.18 μm, and 0.50 μm / 0.50 μm, using an atomic force microscope (AFM) and a four-probe sheet resistance measuring device under the above measurement conditions. More specifically, the patterned wafer (object to be polished) was measured for the remaining heights of each location after polishing using an atomic force microscope under the above measurement conditions. In Table 5, among the remaining heights at all locations, those where the difference between the maximum and minimum values ​​was 1000 angstroms or less were marked as ○, and those where it exceeded 1000 angstroms were marked as ×.

[0083]

[0084] From the results of Table 5, it can be seen that the polishing pads of Examples 1 to 3 have good step elimination performance and flattening performance, because the ratio of the content of crystalline phase and the content of amorphous phase in the polishing layer measured by pulse NMR method in wet state at 40 ° C, and the ratio of the content of intermediate phase and the content of amorphous phase in the polishing layer are within appropriate ranges.In addition, from the results of Table 5, it can be seen that the polishing pads of Examples 1 to 3 have good step elimination performance and flattening performance, because the value obtained by subtracting the content of intermediate phase in the polishing layer measured by pulse NMR method in dry state at 40 ° C from the content of intermediate phase in the polishing layer measured by pulse NMR method in wet state at 40 ° C, and the value obtained by subtracting the content of amorphous phase in the polishing layer measured by pulse NMR method in dry state at 40 ° C from the content of amorphous phase in the polishing layer measured by pulse NMR method in wet state at 40 ° C are within appropriate ranges. Comparisons of different compounding ratios showed a tendency for improvement in step-eliminating and planarizing performance up to compounding ratios of PTMG constituent units of 30% or more and 80% or less. The addition of the strong cohesive force of the ester system improves the balance between the hard and soft segments, resulting in an optimal structure for the polishing layer during polishing. It is believed that if the polishing layer is too soft, step-eliminating and planarizing performance will deteriorate.

[0085] The present invention contributes to the manufacture and sale of polishing pads and has industrial applicability.

[0086] REFERENCE SIGNS LIST 1 Polishing device 3 Polishing pad 4 Polishing layer 4A Hollow microspheres 6 Cushion layer 7 Adhesive layer 8 Object to be polished 81 Base 82 Metal film 9 Slurry 10 Polishing platen

Claims

1. A polishing pad having a polishing layer made of a polyurethane resin foam made from an isocyanate-terminated prepolymer and a curing agent, characterized in that the ratio of the crystalline phase content (%) to the amorphous phase content (%) in the polishing layer measured at 40°C by pulse NMR in a wet state is 0.5 or more and 1.0 or less, and the ratio of the mesophase content (%) to the amorphous phase content (%) in the polishing layer measured at 40°C by pulse NMR in a wet state is 0.4 or more and 0.9 or less.

2. The polishing pad according to claim 1, wherein the content of amorphous phase in the polishing layer measured at 40°C by pulse NMR in the wet state is 30.0% or more and 55.0% or less.

3. The polishing pad according to claim 1, wherein the content of mesophase in the polishing layer measured at 40°C by pulse NMR in the wet state is 15.0% or more and 35.0% or less.

4. The polishing pad described in claim 1, wherein the isocyanate-terminated prepolymer contains structural units derived from a polyisocyanate compound and structural units derived from a high-molecular-weight polyol, and the structural units derived from a high-molecular-weight polyol contain at least structural units derived from a polyester diol and structural units derived from PTMG.

5. The polishing pad according to claim 4, wherein the polyester diol used to form the polyester diol-derived constitutional units has a number average molecular weight of 600 or more and 2,500 or less.

6. The polishing pad according to claim 4, wherein the PTMG-derived constitutional units account for 30% by weight or more and 80% by weight or less of the high-molecular-weight polyol-derived constitutional units.

7. The polishing pad described in claim 4, wherein the polyurethane resin foam is made from at least two types of isocyanate-terminated prepolymers, at least one of the at least two types of isocyanate-terminated prepolymers contains the PTMG-derived structural unit, and the NCO equivalent of the isocyanate-terminated prepolymer containing the PTMG structural unit is 400 or more and 500 or less.

8. The polishing pad described in claim 4, wherein the polyurethane resin foam is made from at least two types of isocyanate-terminated prepolymers, at least one of the at least two types of isocyanate-terminated prepolymers contains the polyester diol-derived structural unit, and the NCO equivalent of the isocyanate-terminated prepolymer containing the polyester diol structural unit is 550 or more and 700 or less.

9. A polishing pad having a polishing layer made of a polyurethane resin foam made from an isocyanate-terminated prepolymer and a curing agent, wherein the value obtained by subtracting the mesophase content (%) of the polishing layer measured at 40°C by pulse NMR in a dry state from the mesophase content (%) of the polishing layer measured at 40°C by pulse NMR in a wet state is -2.0% or more and 2.0% or less, and the value obtained by subtracting the amorphous phase content (%) of the polishing layer measured at 40°C by pulse NMR in a dry state from the amorphous phase content (%) of the polishing layer measured at 40°C by pulse NMR in a wet state is 2.0% or more and 5.7% or less.

10. The polishing pad according to claim 9, wherein the content of the crystalline phase in the polishing layer measured at 40°C by pulse NMR in the wet state is smaller than the content of the amorphous phase.

11. The polishing pad according to claim 9, wherein the content of amorphous phase in the polishing layer measured at 40°C by pulse NMR in the wet state is 30.0% or more and 55.0% or less.

12. The polishing pad according to claim 9, wherein the content of amorphous phase in the polishing layer measured at 40°C by pulse NMR in the dry state is 30.0% or more and 50.0% or less.

13. The polishing pad of claim 9, wherein the isocyanate-terminated prepolymer comprises a polyisocyanate compound-derived structural unit and a high-molecular-weight polyol-derived structural unit, and the high-molecular-weight polyol-derived structural unit comprises a polyester diol-derived structural unit and a PTMG-derived structural unit.

14. The polishing pad according to claim 13, wherein the polyester diol used to form the polyester diol-derived constitutional units has a number average molecular weight of 600 or more and 2,500 or less.

15. The polishing pad according to claim 13, wherein the PTMG structural units account for 30% by weight or more and 80% by weight or less of the structural units derived from the high-molecular-weight polyol.

16. The polishing pad described in claim 13, wherein the polyurethane resin foam is made from at least two types of isocyanate-terminated prepolymers, at least one of the at least two types of isocyanate-terminated prepolymers contains the PTMG-derived structural unit, and the NCO equivalent of the isocyanate-terminated prepolymer containing the PTMG-derived structural unit is 400 or more and 500 or less.

17. The polishing pad described in claim 13, wherein the polyurethane resin foam is made from at least two types of isocyanate-terminated prepolymers, at least one of the at least two types of isocyanate-terminated prepolymers contains the polyester diol-derived structural unit, and the NCO equivalent of the isocyanate-terminated prepolymer containing the polyester diol-derived structural unit is 550 or more and 700 or less.

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