JP7749445B2 - Polishing pad, manufacturing method thereof, and manufacturing method of polished workpiece - Google Patents

Description

The present invention relates to a polishing pad, a method for manufacturing the same, and a method for manufacturing a polished workpiece.

Generally, polishing using a polishing pad is performed on materials such as optical materials such as lenses, plane-parallel plates, and reflecting mirrors, semiconductor wafers, semiconductor devices, hard disk substrates, metals, and ceramics.

In polishing processes, various polishing pads have been developed with the aim of improving the flatness of the polishing surface of the workpiece and the polishing rate of the polishing process. For example, Patent Document 1 discloses a polishing pad that is a non-porous molded body of thermoplastic polyurethane, characterized in that the maximum value of the loss tangent of the thermoplastic polyurethane in the range of -70°C to -50°C is 4.00 x ^10-2 or less. Patent Document 1 also discloses that polishing using such a polishing pad suppresses the generation of burrs at the corners of recesses formed on the polishing surface.

Patent Document 2 discloses a polishing pad having a polishing layer made of polyurethane resin foam having fine bubbles, the polyurethane resin foam containing a polyurethane resin having an Asker D hardness of 20 to 60 degrees and a specific wear parameter within a predetermined range, and further having a bubble count of 200 bubbles/ ^mm2 or more and an average bubble diameter of 50 μm or less. Patent Document 2 discloses that such a polishing pad is less likely to scratch the surface of the material to be polished, has excellent dressing properties, and has a higher polishing rate than conventional polishing pads.

Patent Document 3 discloses a polishing pad for chemical mechanical polishing that includes a porous foam having an average pore size of 50 μm or less, with 75% or more of the pores having a size within 20 μm of the average pore size; the porous foam includes a thermoplastic polyurethane as a polymer resin; and the thermoplastic polyurethane is a thermoplastic polyurethane having specified physical properties. Patent Document 3 also discloses that such a polishing pad can impart excellent flatness to the polished surface of the object being polished.

Patent Document 4 discloses a polishing pad using a polyurethane thermoplastic elastomer foam having a predetermined hardness, characterized in that the foam density is 0.2 to 1.3 g/cm ³ , the average cell diameter is 1 to 10 μm, and the number of cells is 1×10 ⁷ cells/cm ³ or more. Patent Document 4 discloses that such a polishing pad maintains a good foamed state and can impart excellent flatness to the polished surface of the workpiece.

Patent No. 6518680 JP 2014-111296 A Patent No. 4624781 Patent No. 3649385

In general, in polishing processes that require a high degree of flatness, it is preferable to use a high-density polishing pad to ensure appropriate sinking of the polishing pad. However, high-density polishing pads tend to have poor affinity with the slurry used in polishing. For polishing pads, affinity with the slurry is important from the perspective of improving the removal rate and the flatness of the workpiece.

The inventors have conducted a detailed study of conventional polishing pads, including those described in the above patent documents, and have found that conventional polishing pads either have insufficient affinity with the slurry or do not provide sufficient flatness to the object being polished.

For example, non-porous polishing pads such as those disclosed in Patent Document 1 have poor affinity with the slurry because the slurry does not easily penetrate the polishing pad. Furthermore, polishing pads such as those disclosed in Patent Documents 2 to 4 are unable to impart sufficient flatness to the workpiece due to their low density, and also have insufficient affinity with the slurry.

The present invention was made in consideration of the above-mentioned problems, and aims to provide a polishing pad that can impart good flatness to the object being polished and has excellent affinity with slurry, a method for manufacturing the same, and a method for manufacturing a polished object.

As a result of extensive research into solving the above problems, the inventors discovered that the above problems could be solved by using a resin sheet with specific physical properties, leading to the completion of the present invention.

That is, the present invention includes the following aspects.
[1]
A polishing pad comprising a resin sheet having fine holes,
In the pore distribution of the resin sheet measured by mercury intrusion porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm, the cumulative pore volume V in the pore diameter range of 0.100 μm or more and 10.0 μm or less is 0.020 cm ³ /g or more and 0.100 cm ³ /g or less,
The density of the resin sheet is 0.9 g/cm ³ or more and 1.3 g/cm ³ or less.
[2]
The polishing pad according to [1], wherein in the pore distribution of the resin sheet, an integrated pore volume V' in the pore diameter range of 0.050 μm or more and less than 0.100 μm is 0.000 cm ³ /g or more and 0.120 cm ³ /g or less.
[3]
In the pore distribution of the resin sheet, the ratio of the cumulative pore volume V to the cumulative pore volume V ₀ in the pore diameter range of 0.100 μm to 360 μm is 50% or more. [1] or [2] The polishing pad according to.
[4]
In the pore distribution of the resin sheet, the ratio of the cumulative pore volume V to the cumulative pore volume V ₀ ' in the pore diameter range of 0.050 μm or more and 360 μm or less is 50% or more. [1] - [3] A polishing pad according to any one of [1] to [3].
[5]
In the pore distribution of the resin sheet, the peak position of the maximum peak in the pore diameter range of 0.100 μm or more and 360 μm or less is in the pore diameter range of 0.100 μm or more and 10.0 μm or less. [1] to [4]. The polishing pad according to any one of [1] to [4].
[6]
In the pore distribution of the resin sheet, the peak position of the maximum peak in the pore diameter range of 0.050 μm or more and 360 μm or less is in the pore diameter range of 0.050 μm or more and 10.0 μm or less. [1] to [5]. The polishing pad according to any one of [1] to [5].
[7]
The polishing pad according to any one of [1] to [6], wherein in the pore distribution of the resin sheet, the cumulative pore volume V ₀ in the pore diameter range of 0.100 μm or more and 360 μm or less is 0.040 cm ³ /g or more and 0.120 cm ³ /g or less.
[8]
The polishing pad according to any one of [1] to [7], wherein in the pore distribution of the resin sheet, the cumulative pore volume V ₀ ' in the pore diameter range of 0.050 μm or more and 360 μm or less is 0.040 cm ³ /g or more and 0.200 cm ³ /g or less.
[9]
The polishing pad according to any one of [1] to [8], wherein the resin sheet has a microphase separation structure.
[10]
The polishing pad according to any one of [1] to [9], wherein the resin sheet contains polyurethane.
[11]
A polishing pad comprising a resin sheet having fine holes,
In the pore distribution of the resin sheet measured by mercury porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm, the cumulative pore volume V'' in the pore diameter range of 0.050 μm or more and 10.0 μm or less is 0.020 cm ³ /g or more and 0.140 cm ³ /g or less,
The density of the resin sheet is 0.9 g/cm ³ or more and 1.3 g/cm ³ or less.
[12]
A method for producing a polishing pad according to any one of [1] to [11],
A method for producing a polishing pad, comprising the step of curing a mixed liquid of at least one prepolymer and at least two curing agents to obtain a resin sheet having a microphase-separated structure.
[13]
[13] The method for manufacturing a polishing pad according to [12], wherein the curing agent comprises a first curing agent having an NH ₂ equivalent of 100 or more and 300 or less, a second curing agent having an OH equivalent of 200 or more and 500 or less, and a third curing agent having an OH equivalent of 1000 or more and 2000 or less.
[14]
A method for producing a polished product, comprising a polishing step of polishing a workpiece using the polishing pad according to any one of [1] to [11] in the presence of a polishing slurry.

The present invention provides a polishing pad that can impart good flatness to the object being polished and has excellent affinity with slurry, a method for manufacturing the same, and a method for manufacturing a polished object.

FIG. 1 shows the results of measuring the cumulative pore volume (pore distribution) of the resin sheet of Example 1 by mercury intrusion porosimetry. Fig. 2(A) is an SEM image of the surface of the resin sheet of Example 1, observed at 500x magnification using a scanning electron microscope. Fig. 2(B) is a portion of Fig. 2(A) where a microphase-separated structure (gyroid structure) was observed, surrounded by a dashed line. FIG. 3 is an SEM image of the surface of the resin sheet of Example 2 observed with a scanning electron microscope at 500 magnifications. FIG. 4 shows the results of measuring the cumulative pore volume (pore distribution) of the resin sheet of Comparative Example 1 by mercury porosimetry. FIG. 5 is an SEM image of the surface of the resin sheet of Comparative Example 1 observed with a scanning electron microscope at 500 magnifications.

The following describes in detail an embodiment of the present invention (hereinafter referred to as the "present embodiment"); however, the present invention is not limited to this embodiment, and various modifications are possible without departing from the spirit of the present invention.

(Polishing pad)
The polishing pad of this embodiment comprises a resin sheet having fine pores, and in the pore distribution of the resin sheet measured by mercury porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm, the cumulative pore volume V in the pore diameter range of 0.100 μm to 10.0 μm is 0.020 cm ³ /g to 0.100 cm ³ /g, and the density of the resin sheet is 0.9 g/cm ³ to 1.3 g/cm ^3. Because the polishing pad of this embodiment is configured as described above, it can impart good flatness to the object to be polished and has excellent affinity with the slurry.
The polishing pad of this embodiment can also be specified as follows from the viewpoint of the cumulative pore volume V' described below. That is, the polishing pad of this embodiment includes a resin sheet having pores, and in the pore distribution of the resin sheet measured by mercury porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm, the cumulative pore volume V'' in the pore diameter range of 0.050 μm to 10.0 μm is 0.020 cm ³ /g to 0.140 cm ³ /g, and the density of the resin sheet is 0.9 g/cm ³ to 1.3 g/cm ³ . The polishing pad of this embodiment specified in this way can also impart good flatness to the object to be polished and has excellent affinity with the slurry.

The polishing pad of this embodiment is not particularly limited as long as it includes the resin sheet of this embodiment, and the polishing pad may have a configuration other than the resin sheet. Examples of the configuration other than the resin sheet in the polishing pad include a polishing layer, a cushion layer, and an adhesive layer, which are conventionally known.
In this specification, the term "resin sheet of the present embodiment" refers to "a resin sheet having pores, in which, in the pore distribution of the resin sheet measured by mercury porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm, the cumulative pore volume V in the pore diameter range of 0.100 μm to 10.0 μm is 0.020 cm ³ /g to 0.100 cm ³ /g, and the density of the resin sheet is 0.9 g/cm ³ to 1.3 g/cm ³ " and "a resin sheet having pores, in which, in the pore distribution of the resin sheet measured by mercury porosimetry with a mercury surface tension of 485 dyn/cm, the cumulative pore volume V" in the pore diameter range of 0.050 μm to 10.0 μm is 0.020 cm ³ /g to 0.140 cm ³ /g, and the density of the resin sheet is 0.9 g/cm 3 to 1.3 g/cm 3." The term "resin sheet" as used herein includes both "a resin sheet having a density of ^1.3 to 1.3 g/cm³" and "a resin sheet having a density of 1.3 to 1.3 g/ ^cm³ ."

The polishing pad of this embodiment preferably has the above-mentioned resin sheet as a polishing layer. "Having a resin sheet as a polishing layer" means that at least one surface of the polishing pad of this embodiment corresponds to the surface of the resin sheet of this embodiment, and that surface of the resin sheet becomes the polishing surface that is pressed against the workpiece during polishing of this embodiment. Therefore, the polishing pad of this embodiment preferably has at least one surface made of the resin sheet of this embodiment. Alternatively, the polishing pad of this embodiment may consist solely of the resin sheet of this embodiment.

The polishing pad of this embodiment may have grooves, embossing, and/or holes (punching) on the polishing surface as needed, and may also have a light-transmitting portion. There are no particular limitations on the shape of the grooves and embossing, and examples include lattice, concentric circle, and radial shapes.

(Resin sheet)
(density)
The resin sheet in this embodiment has a density of 0.9 g/cm or ^more and 1.3 g/cm ^{or less} . When the density of the resin sheet in this embodiment is 0.9 g/cm ^{or more} , that is, when the resin sheet is high-density, the polishing pad is less likely to deform under pressure, and therefore, during polishing, the force applied from the polishing pad to the workpiece becomes uniform in the direction of the polishing surface. As a result, in polishing using a polishing pad equipped with such a resin sheet, the polished surface of the workpiece can be made even flatter. In this specification, "the polished surface of the workpiece is flat" means that the polished surface of the workpiece is flatter overall. This can also be said to have good global flatness.
From the same viewpoint, the density of the resin sheet in this embodiment is preferably greater than 0.9 g/cm ³ , more preferably greater than or equal to 1.0 g/cm ³ , and even more preferably greater than or equal to 1.1 g/cm ³ . Note that a density of the resin sheet greater than 0.9 g/cm ³ means that the density of the resin measured to two significant digits is greater than or equal to 0.91 g/cm ³ .
In this embodiment, when the density of the resin sheet is 1.3 g/cm ³ or less, the hardness of the resin sheet tends to be low, and the occurrence of scratches tends to be suppressed during polishing processing using a polishing pad equipped with such a resin sheet.
The density of the resin sheet in this embodiment can be measured by a conventionally known method. For example, the mass and volume of a resin sheet piece can be measured by a conventional method, and the density can be calculated from the obtained values. The method for controlling the density of the resin sheet is not particularly limited, but for example, a polishing pad can be obtained by the polishing pad manufacturing method of this embodiment described below. In particular, in the manufacturing process of the resin sheet in this embodiment, the density of the resin sheet can be increased by reducing the amount of foaming agent or not using a foaming agent.

(Pore distribution of resin sheet)
(Cumulative pore volume V)
The resin sheet in this embodiment has pores, and in the pore distribution measured by mercury intrusion porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm, the cumulative pore volume V in the pore diameter range of 0.100 μm or more and 10.0 μm or less is 0.020 cm ³ /g or more and 0.100 cm ³ /g or less.
In the following description, unless otherwise specified, the term "pore distribution" refers to a pore distribution measured by mercury porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm. Mercury porosimetry is a method for measuring the pore distribution on the surface of a sample by filling mercury into the pores on the surface of the sample while sweeping the applied pressure. Therefore, when measuring the pore distribution of a foamed material by mercury porosimetry, the pore distribution mainly reflects the pore distribution of interconnected cells (generally also referred to as "open cells"), and the contribution of the pore distribution of closed cells is small.

Regarding the polishing pad of this embodiment, the inventors have found that, in the pore distribution measured by mercury porosimetry, when the cumulative pore volume V in the pore diameter range of 0.100 μm to 10.0 μm is 0.020 cm ³ /g or more, the affinity of the polishing pad with the slurry is sufficiently good.This is presumably because, when the cumulative pore volume V is 0.020 cm ³ /g or more, interconnected pores having a pore diameter of 0.100 μm to 10.0 μm are distributed throughout the resin sheet, and during polishing, the slurry penetrates evenly into the resin sheet through these interconnected pores.However, the reason why the cumulative pore volume V is 0.020 cm ³ /g or more makes the affinity of the polishing pad with the slurry sufficiently good is not limited to the above.
From the viewpoint of further improving the affinity with the slurry, in the resin sheet of this embodiment, the cumulative pore volume V is preferably 0.030 cm ³ /g or more, more preferably 0.040 cm ³ /g or more, and even more preferably 0.050 cm ³ /g or more. Furthermore, when the cumulative pore volume V is within the above range, the resin sheet has high density yet excellent dressability. Note that "dressing" or "dressing treatment" refers to a process of adjusting the surface roughness or flatness of the polishing surface of the polishing pad using a dressing jig (e.g., a diamond dresser or sandpaper) to which abrasive grains or the like are fixed before polishing the polished object. Furthermore, "excellent dressability" means that sufficient dressing treatment can be performed by treatment under relatively easy conditions. "Polishing surface" refers to the surface that the polishing pad contacts with the polished object when polishing the polished object with the polishing pad, or the surface that is expected to contact the polished object.
In the resin sheet of this embodiment, the cumulative pore volume V is 0.100 cm ³ /g or less. By having a cumulative pore volume V of 0.100 cm ³ /g or less, the density of the resin sheet tends to be within the above range, and in a polishing process using a polishing pad equipped with such a resin sheet, the polished surface of the workpiece can be made even flatter. From the same viewpoint, the cumulative pore volume V is preferably 0.090 cm ³ /g or less, more preferably 0.080 cm ³ /g or less.

(Cumulative pore volume V')
In the pore distribution of the resin sheet in this embodiment, the cumulative pore volume V' in the pore diameter range of 0.050 μm or more and less than 0.100 μm is typically 0.000 cm ³ /g or more and 0.120 cm ³ /g or less, and from the viewpoint of further improving the balance between the flatness imparted to the workpiece and the affinity with the slurry, it is preferably 0.000 cm ³ /g or more and 0.100 cm ³ /g or less, and more preferably 0.000 cm ³ /g or more and 0.080 cm ³ /g or less.
From the above viewpoint, the polishing pad of this embodiment has a resin sheet having pores, and in the pore distribution of the resin sheet measured by mercury porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm, the cumulative pore volume V'' in the pore diameter range of 0.050 μm to 10.0 μm can be specified to be 0.020 cm ³ /g or more and 0.140 cm ³ /g or less, and the density of the resin sheet can be specified to be 0.9 g/cm ³ or more and 1.3 g/cm ³ or less. In this embodiment, the cumulative pore volume V'' in the pore diameter range of 0.050 μm or more and 10.0 μm or less can be specified as the sum of the cumulative pore volume V and the cumulative pore volume V' in this embodiment, and from the viewpoint of further improving the balance between the flatness imparted to the workpiece and the affinity with the slurry, it is 0.020 cm ³ /g or more and 0.140 cm ³ /g or less, preferably 0.030 cm ³ /g or more and 0.130 cm ³ /g or less, and more preferably 0.050 cm ³ /g or more and 0.120 cm ³ /g or less.

(Ratio of cumulative pore volume V to cumulative pore volume V ₀ )
In the polishing pad of this embodiment, from the viewpoint of further improving the balance between the flatness imparted to the workpiece and the affinity with the slurry, in the pore distribution of the resin sheet, the ratio of the cumulative pore volume _V in the pore diameter range of 0.100 μm to 10.0 μm to the cumulative pore volume V in the pore diameter range of 0.100 μm to 360 μm is preferably 50% or more. In other words, the ratio (V/V ₀ ) of the cumulative pore volume _V to the cumulative pore volume V is preferably 0.50 or more. According to such an embodiment, the resin sheet has an increased proportion of pores having relatively small pore diameters, so that the resin sheet can further increase the number of interconnected cells in the resin sheet while maintaining a high density.
From the same viewpoint, the ratio of the integral pore volume _V to the integral pore volume V is more preferably 60% or more, even more preferably 65% or more, and even more preferably 70% or more. The upper limit of the ratio of the integral pore volume _V to the integral pore volume V is not particularly limited, and the ratio of the integral pore volume _V to the integral pore volume V may be 100% or less, 99% or less, 95% or less, 90% or less, or 80% or less.
In the pore distribution of the resin sheet of this embodiment, the ratio of the cumulative pore volume V to the cumulative pore volume _V ' in the pore diameter range of 0.050 μm or more and 360 μm or less (V/V _' ) is, from the same viewpoint as above, preferably 50% or more, more preferably 60% or more, even more preferably 65% or more, and still more preferably 70% or more. Furthermore, V/ _V ' may be 100% or less, 99% or less, 95% or less, 90% or less, or 80% or less.

(Peak position of the maximum peak)
In the pore distribution of the resin sheet in this embodiment, the peak position of the maximum peak in the pore diameter range of 0.100 μm to 360 μm is preferably within the pore diameter range of 0.100 μm to 10.0 μm. Generally, in mercury intrusion porosimetry, the pore distribution is measured as the cumulative pore volume from the largest pore diameter in the measurement range. Therefore, "the peak position of the maximum peak in the pore diameter range of 0.100 μm to 360 μm" means the position (pore diameter) of the maximum peak of the log differential pore volume distribution (dV / d (log D)) calculated from the pore distribution obtained by mercury intrusion porosimetry. Furthermore, when there are multiple maximum points in the pore diameter range of 0.100 μm to 360 μm, the maximum peak means the maximum point with the largest maximum value.
By having the peak position of the maximum peak in the pore diameter range of 0.100 μm to 360 μm be within the pore diameter range of 0.100 μm to 10.0 μm, the resin sheet has pores with a more uniform distribution in the range of 0.100 μm to 10.0 μm, which tends to further improve the affinity with the polishing pad slurry and dressability. From the viewpoint of further improving the affinity with the polishing pad slurry and dressability, the peak position of the maximum peak in the pore diameter range of 0.100 μm to 360 μm is more preferably within the pore diameter range of 0.500 μm to 5.00 μm.
Furthermore, in the pore distribution of the resin sheet in this embodiment, the peak position of the maximum peak in the pore diameter range of 0.050 μm or more and 360 μm or less is preferably within the pore diameter range of 0.050 μm or more and 10.0 μm or less, and more preferably within the pore diameter range of 0.050 μm or more and 5.00 μm or less.

(Number of peaks and peak height)
In the pore distribution of the resin sheet in this embodiment, the number of peaks in the pore diameter range of 0.100 μm or more and 360 μm or less is preferably 1 or more and 3 or less, more preferably 1 or more and 2 or less, and even more preferably 1. When the number of peaks is within the above range, the pores have a more uniform distribution, which tends to further improve the affinity with the polishing pad slurry and the dressability.
From the same viewpoint, when there are two or more peaks in the pore diameter range of 0.100 μm or more and 360 μm or less, the peak height of the maximum peak is preferably at least two times, more preferably at least five times, and even more preferably at least 10 times the peak height of the second highest peak.

(Cumulative pore volume V ₀ )
In the pore distribution of the resin sheet in this embodiment, the cumulative pore volume _V0 in the pore diameter range of 0.100 μm to 360 μm is preferably 0.040 ^cm3 /g to 0.120 ^cm3 /g, more preferably 0.050 ^cm3 /g to 0.110 ^cm3 /g, and even more preferably 0.060 ^cm3 /g to 0.100 ^cm3 /g. When the cumulative pore volume _V0 is within the above range, the balance between the flatness imparted to the workpiece and the affinity with the slurry tends to be further improved.
Furthermore, in the pore distribution of the resin sheet in this embodiment, the cumulative pore volume V ₀ ' in the pore diameter range of 0.050 μm or more and 360 μm or less can be specified as the sum of the cumulative pore volume V ₀ and the cumulative pore volume V ' in this embodiment, and from the same viewpoint as above, it is preferably 0.040 cm ³ /g or more and 0.200 cm ³ /g or less, more preferably 0.050 cm ³ /g or more and 0.180 cm ³ /g or less, and even more preferably 0.060 cm ³ /g or more and 0.160 cm ³ /g or less.

In this embodiment, the values of the cumulative pore volume V, the cumulative pore volume V', the cumulative pore volume V'', the cumulative pore volume _V0 , the peak position of the cumulative pore volume _V0 ' maximum peak, the number of peaks, and the peak height are calculated from the pore distribution measured by mercury porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm, but for more detailed measurement conditions of the mercury porosimetry, refer to the method described in the Examples. Furthermore, the method for controlling the values of the cumulative pore volume V, the cumulative pore volume V', the cumulative pore volume V'_' , the cumulative pore volume _V0 , and the cumulative pore volume V0' maximum peak position, the number of peaks, and the peak height is not particularly limited, but for example, a polishing pad may be obtained by the polishing pad manufacturing method of this embodiment described below.

(Structure of resin sheet)
The resin sheet in this embodiment preferably has a microphase-separated structure. In this specification, the term "microphase-separated structure" refers to a phase-separated structure formed through microphase separation. In addition, in this specification, the term "microphase separation" refers to phase separation in which a microscopic (typically on the order of micrometers) structural pattern is repeated with at least one-dimensional periodicity in a macroscopically homogeneous object. Microphase separation can be achieved, for example, by employing preferred manufacturing conditions in the manufacturing method of the polishing pad of this embodiment, which will be described later. Typical examples of the microphase-separated structure include, but are not limited to, a spherical structure (island-sea structure), a cylindrical structure, a lamellar structure, and a three-dimensional network structure. The microphase-separated structure in this embodiment preferably includes a cylindrical structure, a lamellar structure, and a three-dimensional network structure, and more preferably a three-dimensional network structure.
In this specification, a three-dimensional network structure refers to a structure in which a mesh-like network is formed in three dimensions. The three-dimensional network structure derived from microphase separation may include a single gyroid structure and/or a double (multiple) gyroid structure. In this specification, a single gyroid structure typically refers to a network structure in which two twisted three-way branches are combined to form a pair of thin wire structures to form a unit cell, which is then periodically repeated, and a double (multiple) gyroid structure refers to a structure in which two or more single gyroid structures are combined in a nested manner.
In the cross section of a resin sheet having a continuous foam structure resulting from conventional foaming agents or injecting an inert gas, a generally spherical foam cross section and flat resin portions (i.e., a sea-island structure consisting of a sea of resin and islands of voids) tend to be observed. On the other hand, when the resin sheet of the present embodiment has a double (multiple) gyroid structure, a phase-separated structure in which two or more resins are intertwined in a mottled manner on the order of micrometers tends to be observed in the cross section. Furthermore, when the resin sheet of the present embodiment has a single gyroid structure, an amorphous void cross section and a resin skeleton/resin skeleton cross section are typically observed in the cross section. When the resin skeleton is sufficiently large compared to the voids, the resin skeleton may not be observable and the sheet may be observed as essentially a sea of resin. However, even in this case, the voids in the resin sheet of the present embodiment are formed in a three-dimensional network-like interconnection.
When a cross section of the resin sheet in this embodiment is observed, both the characteristics of a mottled pattern of two or more resins, an amorphous void cross section, and a resin skeleton/resin skeleton cross section are observed; that is, there are cases where the boundary between the double (multiple) gyroid structure and the single gyroid structure cannot be clearly distinguished, but in such cases, the resin sheet can be evaluated as including at least one of a single gyroid structure and a double (multiple) gyroid structure.
Even when the resin sheet in this embodiment has a single gyroid structure and/or a double (multiple) gyroid structure, a sharp peak (maximum value) is typically measured in the pore diameter range of 0.100 μm or more and 10.0 μm or less in the log differential pore volume distribution.
Preferred structures observed in the polishing pad of this embodiment will be described in detail below, but it is assumed that each structure is derived from microphase separation.

The resin sheet of this embodiment may contain two or more phases with different compositions. In this specification, the "composition" of a phase includes both the resin that is the main component of the phase and the components contained in the phase other than the main component, and also takes into consideration the blending ratio of these. Therefore, the microphase-separated structure possessed by the resin sheet of this embodiment may contain two or more phases in which at least one of the resin that is the main component of the phase and the components contained in the phase other than the main component is different from each other, and typically may contain two or more phases in which at least one or more of the structure, average molecular weight, and functional group of the resin that is the main component of the phase is different.

Examples of two phases with different compositions include cases where the types of resin that make up one phase are different from those of the other phase; cases where the amount of additives contained in one phase is different from those of the other phase; and cases where the resin sheet is made of an AB block polymer, with one phase consisting primarily of the A block and the other phase consisting primarily of the B block.

Typical examples of microphase-separated structures containing two phases with different compositions include a first phase formed by the curing of a specific prepolymer and a specific curing agent, and a second phase formed by the curing of a prepolymer different from the prepolymer in the first phase and the curing agent in the first phase; a first phase formed by the curing of a specific prepolymer and a specific curing agent, and a second phase formed by the curing of a prepolymer different from the prepolymer in the first phase and a curing agent different from the curing agent in the first phase; and a first phase formed by the curing of a specific prepolymer and a specific curing agent, and a second phase formed by the curing of a prepolymer different from the prepolymer in the first phase and a curing agent different from the curing agent in the first phase.

The resin sheet in this embodiment may have voids resulting from microphase separation. These voids may be referred to as voids that constitute a microphase-separated structure, and specific examples thereof include, but are not limited to, voids defined by the resin skeleton that gives rise to a gyroid structure. Note that, in this specification, the voids may originate from pores, or may originate from interconnected pores that connect multiple pores.

The resin sheet having the microphase separation structure of this embodiment can be obtained, for example, by the polishing pad manufacturing method of this embodiment described below. Furthermore, the fact that the resin sheet has a microphase separation structure can be confirmed by observing it with a scanning electron microscope (SEM) at a magnification of approximately 300x to 3000x.

The fact that a resin sheet has a microphase-separated structure containing two or more phases with different compositions or that it has the aforementioned voids can be observed using optical methods such as optical microscopes and phase-contrast microscopes, methods using electron microscopes such as scanning electron microscopes and transmission electron microscopes, methods using particle scattering such as light scattering, small-angle neutron scattering, and small-angle X-ray scattering, X-ray diffraction methods, fluorescence methods, and pulsed NMR measurement methods.

(Average thickness of resin sheet)
The average thickness of the resin sheet in this embodiment is not particularly limited, but is preferably 0.5 mm or more and 10.0 mm or less, more preferably 0.6 mm or more and 8.0 mm or less, and even more preferably 0.7 mm or more and 5.0 mm or less.

(Physical properties of resin sheet)
The compressibility of the resin sheet in this embodiment is not particularly limited, but is preferably 0.1% to 10.0%, more preferably 0.5% to 5.0%. The compressibility of the resin sheet can be determined using a Schopper-type thickness gauge (pressure surface: circular, 1 cm diameter) in accordance with Japanese Industrial Standards (JIS L 1021). Specifically, the thickness t0 is measured after applying an initial load for 30 seconds from an unloaded state, and then the thickness t1 is measured after applying a final pressure for 30 seconds from the thickness t0 state, and the compressibility can be calculated using the following formula. The initial load is 100 g/ ^cm2 , and the final pressure is 1120 g/ ^cm2 .
Compression rate (%) = 100 × (t0 - t1) / t0

The compressive modulus of the resin sheet in this embodiment is not particularly limited, but is preferably 65% to 98%, more preferably 70% to 95%. The compressive modulus of the resin sheet can be determined using a Schopper-type thickness gauge (pressure surface: circular, 1 cm diameter) in accordance with Japanese Industrial Standards (JIS L 1021). Specifically, the thickness t0 is measured after applying an initial load for 30 seconds from an unloaded state, then the thickness t1 is measured after applying a final pressure for 30 seconds from the unloaded state. Furthermore, all loads are removed from the unloaded state, and the sheet is left for 5 minutes (unloaded state). Then, the thickness t0' is measured after applying the initial load again for 30 seconds, and the modulus can be calculated using the following formula. The initial load is 100 g/cm ² and the final pressure is 1120 g/cm ² .
Compressive elastic modulus (%) = 100 × (t0' - t1) / (t0 - t1)

The Shore D hardness of the resin sheet in this embodiment is not particularly limited, but is preferably 30 or more and 90 or less, and more preferably 40 or more and 80 or less. The Shore D hardness of the resin sheet can be determined using a D-type hardness tester in accordance with Japanese Industrial Standards (JIS K 7311).

(Resin sheet material)
The material of the resin sheet in this embodiment is not particularly limited. Examples of materials for the resin sheet include polyurethane resins. Examples of polyurethane resins include, but are not limited to, polyester-based polyurethane resins, polyether-based polyurethane resins, and polycarbonate-based polyurethane resins. These may be used alone or in combination of two or more.

Among these, the material for the resin sheet in this embodiment preferably contains at least one of a polyester-based polyurethane resin and a polyether-based polyurethane resin. In particular, it preferably contains a polyurethane resin that is a cured product of a mixed liquid containing a urethane prepolymer and at least two types of curing agents, as described below in the method for manufacturing a polishing pad of this embodiment. By using such a resin, it tends to be possible to easily achieve a density and pore distribution within the above ranges.

In addition to the resin component, the resin sheet of this embodiment may also contain components derived from additives. Examples of such additives include antifoaming agents, catalysts, foaming agents, foam stabilizers, abrasive grains, dyes, pigments, solid fine particles, flame retardants, hydrophilizing agents, hydrophobic agents, light resistance agents, antioxidants, and antistatic agents, which will be described later in the method for producing a polishing pad of this embodiment.

[Method of manufacturing polishing pad]
The method for producing a polishing pad of this embodiment includes a step of obtaining a resin sheet having a microphase separation structure by curing a mixture of at least one prepolymer and at least two curing agents. According to this method, the polishing pad of this embodiment can be easily produced. Below, each step of the method for producing a polishing pad is described in detail.

(Mixing process)
The manufacturing method of the polishing pad of this embodiment can include a mixing step of preparing a mixture of at least one prepolymer and at least two curing agents.By using at least two curing agents in the mixing step, a resin sheet having a microphase separation structure can be obtained in the molding step after the mixing step.In particular, by using two or more curing agents to form a microphase separation structure, it is easier to control the curing reaction than when using two or more prepolymers to form a microphase separation structure, and the shape of the microphase separation structure tends to be easier to control.

The mixing process can be carried out, for example, by placing at least one prepolymer and at least two curing agents heated to 30°C to 90°C into a temperature-adjustable jacketed mixer and stirring at 30°C to 130°C. If necessary, the mixture can be transferred to a tank with a jacket and a stirrer for aging. The stirring time can be adjusted appropriately depending on the number of mixer teeth, rotation speed, clearance, etc., but is, for example, 0.1 to 60 seconds.

(hardening agent)
The curing agent used in the mixing step is not particularly limited, but examples thereof include an amino group-containing compound and a hydroxyl group-containing compound. Examples of the amino group-containing compound include, but are not particularly limited to, 4,4'-methylenebis(2-chloroaniline) (MOCA), ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 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- Examples of the amino group-containing compound include 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, trimethylethylene bis-4-aminobenzoate, and polytetramethylene oxide-di-p-aminobenzoate. The amino group-containing compound is preferably 4,4'-methylenebis(2-chloroaniline).

Hydroxyl group-containing compounds are not particularly limited, but examples include ethylene glycol, propylene 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, and tetramethylene glycol. Examples of suitable hydroxyl group-containing compounds include glycol, 3-methyl-4,3-pentanediol, 3-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, polytetramethylene glycol, polyethylene glycol, and polypropylene glycol. From the standpoint of reaction control, it is preferable to use a difunctional (diol) hydroxyl group-containing compound rather than a trifunctional or higher functional compound. Furthermore, polytetramethylene glycol is more preferred as the hydroxyl group-containing compound.

The above curing agents are used in combination of two or more types. There are no particular restrictions on the combination of curing agents, but the combinations described below are preferred.

The active hydrogen equivalent (e.g., _NH2 equivalent and OH equivalent) of the curing agent is not particularly limited and may be, for example, 50 to 5,000, 100 to 4,000, or 130 to 3,000. The OH equivalent of a curing agent that is a hydroxyl group-containing compound may be 100 to 5,000, 200 to 4,000, or 300 to 3,000. The _NH2 equivalent of a curing agent that is an amino group-containing compound may be 50 to 2,000, 75 to 1,000, or 100 to 300.

At least two types of curing agents are used in the mixing step. It is preferable to use a combination of curing agents that have low compatibility with each other, and/or different reactivities, and/or different active hydrogen equivalents. This tends to more reliably obtain a microphase-separated structure. Examples of combinations of curing agents with different reactivities include combinations of curing agents with different active hydrogen groups, and more specifically, combinations of amino group-containing compounds and hydroxyl group-containing compounds.

When two or more curing agents having the same active hydrogen group are used, i.e., when two or more hydroxyl group-containing compounds or two or more amino group-containing compounds are used, the two or more curing agents preferably include two curing agents whose active hydrogen equivalent difference is 500 or more and 2000 or less. More preferably, the two or more curing agents include one curing agent whose active hydrogen equivalent is 200 or more and 500 or less, and another curing agent whose active hydrogen equivalent is 1000 or more and 2000 or less.

When using two or more curing agents with the same active hydrogen group, and the difference in active hydrogen equivalent between these two or more curing agents is between 500 and 2000, the ratio of the amount of the curing agent with the smaller active hydrogen equivalent to the amount of the curing agent with the larger active hydrogen equivalent, in terms of the number of active hydrogen groups, is preferably 1:1 to 15:1, and more preferably 1:1 to 10:1.

When two or more curing agents having the same active hydrogen group are used, and these two or more curing agents include one with an active hydrogen equivalent of 200 to 500 and another with an active hydrogen equivalent of 1,000 to 2,000, the ratio of the amount of curing agent with an active hydrogen equivalent of 200 to 500 used to the amount of curing agent with an active hydrogen equivalent of 1,000 to 2,000 used, in terms of the number of active hydrogen groups, is preferably 1:1 to 15:1, and more preferably 1:1 to 10:1.

As a specific preferred combination of curing agents, the at least two curing agents preferably include an amino group-containing compound and a hydroxyl group-containing compound. The at least two curing agents more preferably include one amino group-containing compound and two or more hydroxyl group-containing compounds, or two or more amino group-containing compounds and one hydroxyl group-containing compound. The at least two curing agents even more preferably include one amino group-containing compound and two or more hydroxyl group-containing compounds.

When the at least two curing agents contain an amino group-containing compound and a hydroxyl group-containing compound, the difference between the _NH2 equivalent of the amino group-containing compound and the OH equivalent of the hydroxyl group-containing compound is not particularly limited, but it is preferable that the OH equivalent of the hydroxyl group-containing compound is larger, and it is more preferable that the OH equivalent of the hydroxyl group-containing compound is larger by 100 or more and 2000 or less than the _NH2 equivalent of the amino group-containing compound.

When the at least two curing agents contain an amino group-containing compound and a hydroxyl group-containing compound, the ratio of the amount of the amino group-containing compound used to the total amount of curing agents used is preferably 35% or more and 95% or less, and more preferably 40% or more and 90% or less, in terms of functionality ratio.

An example of a preferred combination of curing agents includes at least two curing agents: a first curing agent (amino group-containing compound) having _{an NH2} equivalent of 100 to 300; a second curing agent (hydroxyl group-containing compound) having an OH equivalent of 200 to 600; and a third curing agent (hydroxyl group-containing compound) having an OH equivalent of 1,000 to 2,000. The ratio of the amount of the first curing agent to the amount of the second curing agent to the amount of the third curing agent is not particularly limited, but the amount of the first curing agent used is preferably 30% to 95% in terms of the ratio of the number of functional groups, and more preferably 40% to 90% in terms of the ratio of the number of functional groups, relative to the total amount of curing agents used. The amount of the second curing agent used is preferably 1% to 70% in terms of the ratio of the number of functional groups, and more preferably 5% to 60% in terms of the ratio of the number of functional groups, relative to the total amount of curing agents used. The amount of the third curing agent used is preferably 3% or more and 60% or less, more preferably 5% or more and 50% or less, in terms of the ratio of the number of functional groups, to the total amount of the curing agents used.

Generally, the total amount of curing agent used is determined by the R value, which is the equivalent ratio of the active hydrogen groups (amino groups and hydroxyl groups) present in the curing agent when the number of functional groups in the prepolymer is taken as 1. The total amount of curing agent used is preferably adjusted so that the R value is 0.7 or more and 1.3 or less. The R value is more preferably 0.8 or more and 1.2 or less.

In addition, by using the above-mentioned preferred combination of curing agents in appropriate amounts, it is possible to more reliably obtain a resin sheet having a microphase-separated structure, and/or a resin sheet having an integrated pore volume V of 0.020 cm ³ /g or more and 0.100 cm ³ /g or less in the pore diameter range of 0.100 μm or more and 10.0 μm or less in the pore distribution measured by mercury porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm. It is possible to use a combination of curing agents that use two or more curing agents with low compatibility with each other, two or more curing agents with different reactivities, and/or curing agents with different active hydrogen equivalents. Even if a resin sheet having a clear microphase-separated structure cannot be obtained by such a combination, a resin sheet having a microphase-separated structure tends to be obtained by adjusting the type of curing agent to increase compatibility, changing the curing agent to have similar reactivities, and/or changing the curing agent to have similar active hydrogen equivalents.

(prepolymer)
The prepolymer used in the mixing step is not particularly limited, and examples thereof include urethane prepolymers. Examples of urethane prepolymers include an adduct of hexamethylene diisocyanate and hexanetriol; an adduct of 2,4-tolylene diisocyanate and prenzcatechol; an adduct of 2,4-tolylene diisocyanate, poly(oxytetramethylene)glycol, and diethylene glycol; an adduct of tolylene diisocyanate and hexanetriol; an adduct of tolylene diisocyanate and trimethylolpropane; an adduct of xylylene diisocyanate and trimethylolpropane; an adduct of hexamethylene diisocyanate and trimethylolpropane; and an adduct of isocyanuric acid and hexamethylene diisocyanate. Furthermore, other isocyanate group-containing compounds prepared by reacting a polyisocyanate compound with a polyol compound, as well as various commercially available urethane prepolymers, may also be used.

The polyisocyanate compound used to prepare the isocyanate group-containing 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, and 3,3'-dimethyl-4,4'-biphenyl diisocyanate. Examples include ethyldiphenylmethane-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, and ethylidine diisothiocyanate.

These polyisocyanate compounds may be used alone or in combination of two or more. Diisocyanate compounds are preferred as polyisocyanate compounds, with 2,4-TDI, 2,6-TDI, and MDI being more preferred.

Examples of polyol compounds used in preparing isocyanate group-containing compounds include diol compounds and triol compounds such as ethylene glycol, diethylene glycol (DEG), and butylene glycol; polyether polyol compounds such as polypropylene glycol (PPG) and poly(oxytetramethylene) glycol (PTMG); polyester polyol compounds such as the reaction product of ethylene glycol and adipic acid or the reaction product of butylene glycol and adipic acid; polycarbonate polyol compounds, and polycaprolactone polyol compounds. Trifunctional propylene glycol with added ethylene oxide can also be used. Polyol compounds may be used alone or in combination of two or more.

The NCO equivalent of the urethane prepolymer is preferably 150 or more and 700 or less, more preferably 200 or more and 600 or less, and even more preferably 200 or more and 500 or less. "NCO equivalent" is a numerical value indicating the molecular weight of the urethane prepolymer per NCO group, calculated by the formula "(parts by mass of polyisocyanate compound + parts by mass of polyol compound) / [(number of functional groups per molecule of polyisocyanate compound × parts by mass of polyisocyanate compound / molecular weight of polyisocyanate compound) - (number of functional groups per molecule of polyol compound × parts by mass of polyol compound / molecular weight of polyol compound)]".

At least one type of prepolymer is used in the mixing step. Two or more of the above prepolymers may be used in combination, but preferably one type is used alone. This type of prepolymer tends to make it easier to control the curing reaction and the shape of the microphase-separated structure. It is preferable to use a urethane prepolymer containing tolylene diisocyanate as the main component alone as the prepolymer.

The amount of prepolymer used is not particularly limited, but is preferably 30 to 80 parts by mass, and more preferably 40 to 75 parts by mass, based on the total mixed solution.

(Additives)
In the mixing step, components other than the prepolymer and the curing agent may be mixed as additives. Examples of additives include solvents (diluents) such as polypropylene glycol; antifoaming agents such as silicone-based antifoaming agents; catalysts; foaming agents such as water and hollow microparticles; foam stabilizers such as silicone-based foam stabilizers; and fillers (abrasive grains) such as cerium oxide; dyes; pigments; solid microparticles; flame retardants; hydrophilizing agents; hydrophobic agents; light resistance agents; antioxidants; and antistatic agents. From the viewpoint of achieving a density of 0.9 g/cm ³ or more and 1.3 g/cm ³ or less, it is preferable to add no foaming agent or to add only a small amount, and it is more preferable to use an antifoaming agent.

By adjusting the type and amount of catalyst added during the mixing process, the reaction rate of the curing reaction can be controlled, and the microphase-separated structure formed can be controlled.

(molding process)
The molding process is a process of obtaining a resin sheet having a microphase separation structure by curing the mixed liquid obtained as described above. For example, the mixed liquid obtained in the mixing process may be poured into a mold preheated to 30°C to 150°C and heated at about 30°C to 150°C for 10 minutes to 5 hours. This causes the prepolymer and the curing agent to react to form a resin, thereby curing the mixed liquid. Furthermore, secondary curing may be performed by heating in an oven at about 50°C to 180°C for 10 minutes to 12 hours. In the method for producing a polishing pad of this embodiment, since the mixed liquid is as described above, a resin block having a microphase separation structure can be obtained.

The reaction temperature when curing the mixed liquid in the molding process can be adjusted appropriately depending on the types and blending ratios of the prepolymer, curing agent, and additives used. Adjusting the reaction temperature tends to control the reaction rate of the curing reaction and the microphase-separated structure that is formed.

In the molding process, a resin sheet of an appropriate thickness is cut out from the resin block obtained as described above to obtain a resin sheet having a microphase-separated structure. The obtained resin sheet may be aged at 30°C to 150°C for approximately 1 hour to 24 hours.

The resin sheet obtained in this manner is then, for example, attached with double-sided tape to one side and cut into a predetermined shape, preferably a disk, to complete the polishing pad of this embodiment. There are no particular restrictions on the double-sided tape, and any double-sided tape known in the art can be selected and used.

The polishing pad of this embodiment may have a single-layer structure consisting of only a resin sheet, or may have a multi-layer structure in which another layer (cushion layer or substrate layer) is bonded to one side of a resin sheet. When it has a multi-layer structure, the multiple layers can be bonded and fixed together using double-sided tape or adhesive, while applying pressure as necessary. There are no particular limitations on the double-sided tape and adhesive used, and any double-sided tape and adhesive known in the art can be selected and used.

Furthermore, the polishing pad of this embodiment may have grooves, embossing, and/or holes (punching) on its surface, as needed. There are no particular limitations on the shape of the grooves and embossing, and examples include lattice, concentric, and radial shapes.

The polishing pad may also be dressed (grinded) on the front and/or back surfaces of the resin sheet. The resin sheet used in the polishing pad manufacturing method of this embodiment is high-density, but has interconnected pores, making it highly dressable and allowing for easy dressing. The dressing method is not particularly limited, and can be performed by a known method such as grinding with a diamond dresser.

[Method of manufacturing polished product]
The method for producing a polished product of this embodiment includes a polishing step in which an object to be polished is polished using the above-mentioned polishing pad in the presence of a polishing slurry to obtain a polished product. The polishing step may be primary polishing (rough polishing), finish polishing, or a combination of both.

In the method for manufacturing a polished workpiece of this embodiment, the polishing slurry is supplied, and the holding platen and polishing platen are rotated relative to each other while the workpiece is pressed against the polishing pad by the holding platen. This causes the workpiece surface to be polished by the polishing pad using chemical mechanical polishing. The holding platen and polishing platen may rotate in the same direction but at different rotational speeds, or in opposite directions. Furthermore, the workpiece may be polished while moving (rotating) inside the frame during the polishing process.

The polishing slurry may contain water, an oxidizing agent such as hydrogen peroxide, chemical components such as acid components and alkaline components, additives, and abrasive grains (abrasive particles; for example, SiC, SiO ₂ , Al ₂ O ₃ , and CeO ₂ ), depending on the object to be polished and the polishing conditions.

The object to be polished is not particularly limited, but examples include optical materials such as lenses, plane-parallel plates, and reflective mirrors, semiconductor wafers, semiconductor devices, hard disk substrates, metals, and ceramics.

The present embodiment will be described in more detail below using examples and comparative examples. The present embodiment is not limited in any way by the following examples.

[Measurement of cumulative pore volume (pore distribution) by mercury intrusion method]
The cumulative pore volume (pore distribution) of the resin sheet was measured by mercury intrusion porosimetry. A 10 mm square sample piece was cut from a 2 mm thick resin sheet and used for measurement. The cumulative pore volume was measured using a Micromeritics product named "Auto Pore III" under conditions of a contact angle of 130° and a mercury surface tension of 485 dyn/cm. The cumulative pore volume from a pore diameter of 360 μm to a pore diameter of 0.005 μm was determined by sweeping the mercury pressure from 0.5 psia to 30,000 psia. The pore distribution was determined using porosimeter data processing software (Shimadzu Corporation, product name "POREPLOT-PCW"). Note that for each measurement result, the pore distribution from a pore diameter of 360 μm to a pore diameter of 0.100 μm is shown.

[Observation of Resin Sheet]
Whether or not the resin sheet had a microphase-separated structure was confirmed by observation with a scanning electron microscope (SEM) at a magnification of about 300 to 3000 times.

[Example 1]
A urethane prepolymer containing 2,4-tolylene diisocyanate (TDI) as a main component and having an NCO equivalent weight of 407 was prepared.

48.7 parts by mass of the above urethane prepolymer was mixed with 14.1 parts by mass of 4,4'-methylenebis( ₂ -chloroaniline) (MOCA) (NH equivalent 134), 5.7 parts by mass of polytetramethylene glycol (OH equivalent 325), and 11.3 parts by mass of polypropylene glycol (OH equivalent 1345). Furthermore, 0.25 parts by mass of a silicone antifoaming agent (manufactured by Dow Corning, product name "71 Additive"), 0.01 parts by mass of a catalyst (manufactured by Tosoh Corporation, product name "Toyocat ET"), and 20.0 parts by mass of cerium oxide filler as abrasive grains were added to the above mixture to obtain a mixture that serves as a precursor to the resin sheet. The R value of the mixture was 1.1.

The resulting mixture was poured into a mold preheated to 50°C and allowed to cure for 15 minutes at 50°C. The resulting block-shaped molded product was removed from the mold and allowed to cure for 8 hours in an oven at 120°C, resulting in a urethane resin block. The resulting urethane resin block was allowed to cool to 25°C and then sliced to obtain a 2.0 mm thick resin sheet.

The density of the obtained resin sheet was 1.2 g/cm ³ , the Shore D hardness was 54 degrees, the compressibility was 0.8%, and the compressive modulus was 85%. The measurement results of the pore distribution are shown in Figure 1. Furthermore, the cumulative pore volume V in the pore diameter range of 0.100 μm or more and 10.0 μm or less, the cumulative pore volume V' in the pore diameter range of 0.050 μm or more and less than 0.100 μm, the cumulative pore volume V ₀ in the pore diameter range of 0.100 μm or more and 360 μm or less, and the ratio V/V ₀ are shown in Table 1, all of which are determined from the pore distribution.

Furthermore, when the surface of the resin sheet was observed with a scanning electron microscope, it was confirmed to have a microphase-separated structure (three-dimensional network structure). Specifically, a mottled structure in which at least two types of resin with different compositions were intertwined was observed, and it was evaluated to have at least a double gyroid structure. More specifically, an example of an SEM image is shown in Figure 2(A). As surrounded by dashed lines in Figure 2(B), a microphase-separated structure was confirmed in multiple locations.

[Example 2]
54.0 parts by mass of the same urethane prepolymer as in Example 1, 4,4'-methylenebis (2-chloroaniline) (MOCA) (NH ₂ equivalent 134) 9.6 parts by mass, 22.9 parts by mass of polytetramethylene glycol (OH equivalent 325), 13.2 parts by mass of polypropylene glycol (OH equivalent 1345), 0.33 parts by mass of a silicone antifoaming agent (manufactured by DOW CORNING, product name "71additive"), 0.01 parts by mass of a catalyst (manufactured by Tosoh Corporation, product name "Toyocat ET") to obtain a mixture that will be a precursor to the resin sheet. The R value of the mixture was 0.9.

The resulting mixture was poured into a mold preheated to 70°C and cured for 10 minutes at 70°C. The resulting block-shaped molded product was removed from the mold and cured for 15 minutes at 120°C in an oven, yielding a urethane resin block. The resulting urethane resin block was allowed to cool to 25°C and then sliced to yield a 2.0 mm thick resin sheet.

The density of the obtained resin sheet was 1.1 g/cm ³ , the Shore D hardness was 64 degrees, the compressibility was 1.3%, and the compressive modulus was 80%. The cumulative pore volume V of the obtained resin sheet, the cumulative pore volume V' in the pore diameter range of 0.050 μm to less than 0.100 μm, the cumulative pore volume V ₀ , and the ratio V/V ₀ were 0.020 cm ³ /g to 0.100 cm ³ /g, 0.000 cm ³ /g to 0.120 cm ³ /g, 0.040 cm ³ /g to 0.120 cm ³ /g, and 50% or more, respectively. When the surface of the resin sheet was observed with a scanning electron microscope, no structure of resin sea portions and void islands was observed, and it was evaluated to have at least a single gyroid structure. An example of an SEM image is shown in FIG. 3.

[Comparative Example 1]
A first urethane prepolymer (NCO equivalent weight: 400) containing 2,4-tolylene diisocyanate (TDI) as a main component, and a second urethane prepolymer (NCO equivalent weight: 200) containing hexamethylene diisocyanate as a main component were prepared.

51.6 parts by mass of the first urethane prepolymer and 17.2 parts by mass of the second urethane prepolymer were mixed with 23.3 parts by mass of 4,4'-methylenebis(2-chloroaniline) (MOCA) (NH ₂ equivalent 134), and 4.7 parts by mass of polytetramethylene glycol (OH equivalent 500). Furthermore, to the above mixture, 1.39 parts by mass of polyether as a diluent, 1.67 parts by mass of a silicone antifoaming agent (manufactured by Dow Corning Corporation, product name "71additive"), 0.04 parts by mass of a catalyst (manufactured by Tosoh Corporation, product name "Toyocat ET"), 0.07 parts by mass of water as a foaming agent, and 0.10 parts by mass of a silicone foam stabilizer (manufactured by Toray Dow Corning Co., Ltd., product name "SH193") were added to obtain a mixture that serves as a precursor to the resin sheet. The R value of the mixture was 0.9.

The resulting mixture was poured into a mold preheated to 50°C and allowed to cure for 15 minutes at 50°C. The resulting block-shaped molded product was removed from the mold and allowed to cure for 8 hours in an oven at 120°C, resulting in a urethane resin block. The resulting urethane resin block was allowed to cool to 25°C and then sliced to obtain a 2.0 mm thick resin sheet.

The density of the obtained resin sheet was 1.1 g/ ^cm3 , the Shore D hardness was 69 degrees, the compressibility was 1.1%, and the compressive modulus was 90%. The measurement results of the pore distribution are shown in Figure 4. Table 1 also shows the cumulative pore volume V in the pore diameter range of 0.100 μm to 10.0 μm, the cumulative pore volume _V0 in the pore diameter range of 0.100 μm to 360 μm, and the ratio V/ _V0, which were obtained from the pore distribution.

Furthermore, when the surface of the resin sheet was observed with a scanning electron microscope, no microphase-separated structure was confirmed. An example of an SEM image is shown in Figure 5. In Comparative Example 1, it is believed that the desired curing reaction did not proceed and microphase separation did not occur, at least due to a lack of curing agent with an OH equivalent of 1,000 or more and 2,000 or less.

A polishing test and an evaluation test of affinity with slurry were conducted using the polishing pads of Examples 1 and 2. As a control, a polishing test and an evaluation test of affinity with slurry were conducted under the same conditions using the polishing pad of Comparative Example 1. The results showed that the polishing pads of the Examples were able to impart better flatness to the workpiece being polished and had superior affinity with slurry compared to the polishing pad of Comparative Example.

The polishing pad of the present invention has industrial applicability as a polishing pad used for polishing (particularly chemical mechanical polishing (CMP)) materials such as optical materials such as lenses, plane-parallel plates, and reflecting mirrors, semiconductor wafers, semiconductor devices, hard disk substrates, metals, and ceramics.

Claims (14)

A polishing pad comprising a resin sheet having fine holes,
In the pore distribution of the resin sheet measured by mercury intrusion porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm, the cumulative pore volume V in the pore diameter range of 0.100 μm or more and 10.0 μm or less is 0.020 cm ³ /g or more and 0.100 cm ³ /g or less,
The density of the resin sheet is 0.9 g/cm ³ or more and 1.3 g/cm ³ or less. 2. The polishing pad according to claim 1, wherein in the pore distribution of the resin sheet, an integrated pore volume V' in the pore diameter range of 0.050 μm or more and less than 0.100 μm is 0.000 cm ³ /g or more and 0.120 cm ³ /g or less. 3. The polishing pad according to claim 1, wherein in the pore distribution of the resin sheet, the ratio of the cumulative pore volume V to the cumulative pore volume V ₀ in the pore diameter range of 0.100 μm to 360 μm is 50% or more. The polishing pad according to any one of claims 1 to 3, wherein in the pore distribution of the resin sheet, the ratio of the cumulative pore volume V to the cumulative pore volume V ₀ ' in the pore diameter range of 0.050 μm or more and 360 μm or less is 50% or more. The polishing pad according to any one of claims 1 to 4, wherein the peak position of the maximum peak in the pore diameter range of 0.100 μm or more and 360 μm or less in the pore distribution of the resin sheet is within the pore diameter range of 0.100 μm or more and 10.0 μm or less. The polishing pad according to any one of claims 1 to 5, wherein the peak position of the maximum peak in the pore diameter range of 0.050 μm or more and 360 μm or less in the pore distribution of the resin sheet is within the pore diameter range of 0.050 μm or more and 10.0 μm or less. 7. The polishing pad according to claim 1, wherein the pore distribution of the resin sheet has an integrated pore volume V ₀ in the pore diameter range of 0.100 μm or more and 360 μm or less of 0.040 cm ³ /g or more and 0.120 cm ³ /g or less. 8. The polishing pad according to claim 1, wherein the pore distribution of the resin sheet has an integrated pore volume V ₀ ' in the pore diameter range of 0.050 μm or more and 360 μm or less of 0.040 cm ³ /g or more and 0.200 cm ³ /g or less. The polishing pad according to any one of claims 1 to 8, wherein the resin sheet has a microphase-separated structure. The polishing pad according to any one of claims 1 to 9, wherein the resin sheet contains polyurethane. A polishing pad comprising a resin sheet having fine holes,
In the pore distribution of the resin sheet measured by mercury porosimetry with a contact angle of 130° and a mercury surface tension of 485 dyn/cm, the cumulative pore volume V'' in the pore diameter range of 0.050 μm or more and 10.0 μm or less is 0.020 cm ³ /g or more and 0.140 cm ³ /g or less,
The density of the resin sheet is 0.9 g/cm ³ or more and 1.3 g/cm ³ or less. A method for producing the polishing pad according to any one of claims 1 to 11, comprising:
A method for producing a polishing pad, comprising the step of curing a mixed liquid of at least one prepolymer and at least two curing agents to obtain a resin sheet having a microphase-separated structure. 13. The method for producing a polishing pad according to claim 12, wherein the curing agent comprises a first curing agent having an NH ₂ equivalent of 100 or more and 300 or less, a second curing agent having an OH equivalent of 200 or more and 500 or less, and a third curing agent having an OH equivalent of 1000 or more and 2000 or less. A method for producing a polished workpiece, comprising a polishing step of polishing an object to be polished using the polishing pad described in any one of claims 1 to 11 in the presence of a polishing slurry.