Polishing pad

Abstract

Provided is a polishing pad capable of polishing an object to be polished at a high polishing rate in a polishing step, and capable of being stably trimmed. A polishing pad which contains 5 mass% or more of a hydrogenated block copolymer (A) that satisfies the following conditions (1)-(2), and which has a static friction coefficient of 1.2 or less as measured in accordance with JIS K7125. Lt; condition (1) gt; the hydrogenated block copolymer (A) is a hydrogenated product of a block copolymer containing a vinyl aromatic monomer unit and a conjugated diene monomer unit. Lt; condition (2) gt; the hydrogenated block copolymer (A) contains at least one polymer block (a) mainly composed of a vinyl aromatic monomer unit, and the content of the polymer block (a) mainly composed of a vinyl aromatic monomer unit in the hydrogenated block copolymer (A) is 10 mass% or more.

Description

Technical Field

[0001] The present invention relates to polishing pads. Background Art

[0002] In the manufacture of integrated circuits and other electronic devices, multiple layers of conductive, semiconducting, and dielectric materials are deposited on or removed from the surface of a semiconductor wafer. Thin layers of conductive, semiconducting, and dielectric materials can be deposited using a variety of deposition techniques.

[0003] Common deposition techniques used in modern processing include physical vapor deposition (PVD), also known as sputtering, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), and electrochemical plating (ECP). As layers of material are deposited and removed, the top surface of the wafer becomes non-planar. Since subsequent semiconductor processing (e.g., metallization) requires a flat wafer surface, planarization is necessary.

[0004] Planarization is useful for removing unwanted surface topography and surface defects such as rough surfaces, agglomerated materials, crystal lattice damage, scratches, and contaminated layers or materials.

[0005] Chemical mechanical planarization or chemical mechanical polishing (CMP) is a common technique for planarizing substrates such as semiconductor wafers. In existing CMP, the wafer is mounted on a carrier assembly and positioned to contact a polishing pad within the CMP apparatus. The carrier assembly provides controllable pressure to the wafer, pressing the wafer against the polishing pad. The pad is moved relative to the wafer (e.g., rotated) by an external driving force. At the same time, a chemical composition ("slurry") or other polishing solution is supplied between the wafer and the polishing pad. In this way, the wafer surface is polished and planarized by the chemical and mechanical action of the pad surface and the slurry. A variety of compositions and methods are used in the manufacture of polishing pads. When used in this specification, the term "semiconductor wafer" is intended to include semiconductor substrates such as unpatterned semiconductors or patterned semiconductors, semiconductor devices, and various packages for various interconnect levels (including single-chip wafers or multi-chip wafers, substrates for light-emitting diodes (LEDs), or other components that require solder connections).

[0006] Patent Document 1 discloses that a high polishing rate can be achieved by using a polishing pad containing a styrene-based thermoplastic elastomer.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2023-58442 Summary of the Invention

[0010] However, the polishing pad described in Patent Document 1 contains a styrene-based thermoplastic elastomer and has a high coefficient of friction, and therefore, it is known that dressing thereof is unstable.

[0011] Problems to be solved by the invention

[0012] In view of the above problems, an object of the present invention is to provide a polishing pad that can polish an object at a high polishing rate in a polishing process and can perform stable dressing.

[0013] Means for solving problems

[0014] [1] A polishing pad comprising 5% by mass or more of a hydrogenated block copolymer (A) satisfying the following conditions (1) and (2), wherein the static friction coefficient measured in accordance with JIS K 7125 is 1.2 or less.

[0015] <Condition (1)>:

[0016] The hydrogenated block copolymer (A) is a hydrogenated product of a block copolymer containing vinyl aromatic monomer units and conjugated diene monomer units.

[0017] <Condition (2)>:

[0018] The hydrogenated block copolymer (A) contains at least one polymer block (a) mainly composed of vinyl aromatic monomer units.

[0019] The content of the polymer block (a) mainly composed of vinyl aromatic monomer units in the hydrogenated block copolymer (A) is 10% by mass or more.

[0020] [2] The polishing pad as described in [1], wherein

[0021] The hydrogenated block copolymer (a) contains at least one hydrogenated copolymer block (b) composed of vinyl aromatic monomer units and conjugated diene monomer units.

[0022] The content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b) is 5% by mass or more and 79% by mass or less.

[0023] [3] The polishing pad according to [2], wherein the content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b) is 45% by mass or more and 79% by mass or less.

[0024] [4] The polishing pad according to any one of [1] to [3], comprising 40% by mass or more of the hydrogenated block copolymer (A).

[0025] [5] The polishing pad according to any one of [1] to [4], comprising 70% by mass or more of the hydrogenated block copolymer (A).

[0026] [6] The polishing pad according to any one of [1] to [5], wherein the value of the dynamic friction coefficient measured in accordance with JIS K7125 is 0.6 or less.

[0027] [7] The polishing pad according to any one of [1] to [6], wherein the content of the polymer block (a) mainly composed of vinyl aromatic monomer units in the hydrogenated block copolymer (A) is 15% by mass or more and 40% by mass or less.

[0028] Effects of the Invention

[0029] According to the present invention, it is possible to provide a polishing pad that can polish an object at a high polishing rate in a polishing step and can perform stable dressing. DETAILED DESCRIPTION

[0030] Polishing pad

[0031] The polishing pad of the present embodiment contains 5% by mass or more of the hydrogenated block copolymer (A) satisfying the following conditions (1) and (2), and has a static friction coefficient of 1.2 or less as measured in accordance with JIS K 7125.

[0032] <Condition (1)>:

[0033] The hydrogenated block copolymer (A) is a hydrogenated product of a block copolymer containing vinyl aromatic monomer units and conjugated diene monomer units.

[0034] <Condition (2)>:

[0035] The hydrogenated block copolymer (A) contains at least one polymer block (a) mainly composed of vinyl aromatic monomer units.

[0036] The content of the polymer block (a) mainly composed of vinyl aromatic monomer units in the hydrogenated block copolymer (A) is 10% by mass or more.

[0037] The polishing pad of the present embodiment includes the above-mentioned configuration, and thus can polish the workpiece at a high polishing rate in the polishing step, and can perform stable dressing.

[0038] There is no particular limitation on the method for adjusting the static friction coefficient to 1.2 or less.

[0039] For example, when the vinyl bond content in all conjugated diene monomer units of the hydrogenated block copolymer (A) is set to a certain value or less, stickiness can be reduced, resulting in a polishing pad with a low static friction coefficient, and a tendency to exhibit stable dressing properties.

[0040] When the content of all vinyl aromatic monomer units is equal to or greater than a certain value, the hydrogenated block copolymer (A) can reduce stickiness and obtain a polishing pad having a low static friction coefficient, and tends to exhibit stable dressing properties.

[0041] When the content of the polymer block (a) mainly composed of vinyl aromatic monomer units is greater than a certain value, the stickiness of the hydrogenated block copolymer (A) decreases, thereby reducing the static friction coefficient. Furthermore, the polishing pad of this embodiment tends to have a low static friction coefficient and exhibit stable dressing properties.

[0042] Among the methods for reducing the static friction coefficient, one example is a method for reducing stickiness, such as reducing the amount of vinyl bonds in all conjugated diene monomer units in the hydrogenated block copolymer (A), increasing the content of the polymer block (a) mainly composed of vinyl aromatic monomer units in the hydrogenated block copolymer (A), etc.

[0043] By distributing the bubble diameters over a relatively wide range, the static friction coefficient can be reduced when the polishing pad is formed. For example, if the difference between the bubble diameters at the 80% cumulative volume frequency and the bubble diameters at the 20% cumulative volume frequency (bubble diameter at the 80% cumulative volume frequency minus bubble diameter at the 20% cumulative volume frequency) is large, the static friction coefficient can be reduced.

[0044] In addition, the polishing pad of this embodiment can also adjust the dynamic friction coefficient. In addition to reducing the static friction coefficient of the hydrogenated block copolymer (A) itself, the addition of an olefin resin (B) can be used to reduce the dynamic friction coefficient.

[0045] (Hydrogenated block copolymer (A))

[0046] The hydrogenated block copolymer (A) used in the polishing pad of the present embodiment is a hydrogenated product of a block copolymer containing vinyl aromatic monomer units and conjugated diene monomer units (the above-mentioned condition (1)).

[0047] <Vinyl aromatic monomer unit>

[0048] Examples of the vinyl aromatic compound constituting the vinyl aromatic monomer unit include, but are not limited to, monomer units derived from styrene, α-methylstyrene, p-methylstyrene, divinylbenzene, 1,1-diphenylethylene, N,N-dimethyl-p-aminoethylstyrene, and N,N-diethyl-p-aminoethylstyrene.

[0049] In particular, styrene is preferred from the viewpoint of the balance between cost and the mechanical strength of the polishing pad containing the hydrogenated block copolymer (A).

[0050] These may be used alone or in combination of two or more.

[0051] <Conjugated diene monomer unit>

[0052] The conjugated diene monomer unit is a monomer unit derived from a diene having one pair of conjugated double bonds.

[0053] Examples of such dienes include, but are not limited to, 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, and 1,3-hexadiene.

[0054] In particular, 1,3-butadiene and isoprene are preferred from the viewpoint of a good balance between moldability and mechanical strength.

[0055] These may be used alone or in combination of two or more.

[0056] In this specification, "mainly" in the constitution of the hydrogenated block copolymer (A) means that the proportion in a predetermined block polymer or polymer block is 85% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more.

[0057] Note that, since the content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b) is 5% by mass or more and 79% by mass or less (the above-mentioned [2]), the polymer block (a) and the hydrogenated copolymer block (b) can be clearly distinguished.

[0058] <Vinyl Bond Amount in All Conjugated Diene Monomer Units>

[0059] In the hydrogenated block copolymer (A), the vinyl bond content in all conjugated diene monomer units is not particularly limited, but is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more.

[0060] Furthermore, it is preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less.

[0061] In this specification, the "vinyl bond amount" refers to the total amount of conjugated diene monomer units bonded with 1,2-vinyl bonds (conjugated dienes embedded in the polymer with 1,2-bonds) and 3,4-vinyl bonds (conjugated dienes embedded in the polymer with 3,4-bonds) relative to all conjugated dienes (wherein, in the case of using 1,3-butadiene as the conjugated diene, it is the 1,2-vinyl bond amount), and it is a concept that includes the state in which the 1,2-vinyl bond or the 3,4-vinyl bond is hydrogenated to become a single bond. That is, although "vinyl" is a name indicating the state of a double bond, the "vinyl bond amount" in this specification includes the amount of bonds in which the so-called vinyl bond is hydrogenated to become a single bond. When measured in the production process of the hydrogenated block copolymer, the total amount of 1,2-vinyl bonds and 3,4-vinyl bonds relative to all conjugated dienes measured before the hydrogenation process is equivalent to the "vinyl bond amount".

[0062] When the vinyl bond content in all conjugated diene monomer units of the hydrogenated block copolymer (A) is 5% by mass or more, precipitation from the solution due to crystallization of the hydrogenated conjugated diene block can be suppressed in the hydrogenation step.

[0063] Furthermore, when the vinyl bond content in all conjugated diene monomer units of the hydrogenated block copolymer (A) is 5% by mass or more, good compatibility with the olefin-based resin (B) described later is exhibited.

[0064] When the vinyl bond content in all conjugated diene monomer units of the hydrogenated block copolymer (A) is 80% by mass or less, stickiness can be reduced, resulting in a polishing pad having a low static friction coefficient, and a tendency to exhibit stable dressing properties.

[0065] The vinyl bond content in all the conjugated diene monomer units of the hydrogenated block copolymer (A) can be controlled within the above-mentioned numerical range by, for example, using a regulator such as a tertiary amine compound or an ether compound described later.

[0066] The vinyl bond content in all conjugated diene monomer units of the hydrogenated block copolymer (A) can be measured by nuclear magnetic resonance (NMR) using the block copolymer before hydrogenation as the analyte, or by infrared spectrophotometry as described in the Examples below. Furthermore, in nuclear magnetic resonance (NMR) measurements using the hydrogenated block copolymer as the analyte, the vinyl bond content can be calculated by counting the total number of unhydrogenated vinyl structures and structures converted to single bonds by hydrogenation.

[0067] <Total vinyl aromatic compound content>

[0068] The content of all vinyl aromatic monomer units in the hydrogenated block copolymer (A) is preferably 40% by mass to 80% by mass, more preferably 50% by mass to 80% by mass, and even more preferably 60% by mass to 80% by mass.

[0069] When the content of all vinyl aromatic monomer units is 40% by mass or more, the hydrogenated block copolymer (A) can reduce stickiness, thereby obtaining a polishing pad having a low static friction coefficient, and tends to exhibit stable dressing properties.

[0070] When the content of all vinyl aromatic monomer units is 80% by mass or less, the polishing pad of the present embodiment has improved adhesion to the object to be polished, and can exhibit high planarization performance in the polishing step.

[0071] The content of all vinyl aromatic monomer units in the hydrogenated block copolymer (A) can be measured using the block copolymer before hydrogenation and the hydrogenated block copolymer after hydrogenation as test objects using an ultraviolet spectrophotometer.

[0072] The content of all vinyl aromatic monomer units in the hydrogenated block copolymer (A) can be controlled within the above numerical range by adjusting mainly the amount of the vinyl aromatic compound added to the polymerization reactor, the reaction temperature, and the reaction time.

[0073] <Polymer Block (a) Mainly Containing Vinyl Aromatic Monomer Units>

[0074] The hydrogenated block copolymer (A) used in the polishing pad of this embodiment contains at least one polymer block (a) mainly composed of vinyl aromatic monomer units (the above-mentioned condition (2)). This can prevent the pellets from sticking together.

[0075] In the hydrogenated block copolymer (A), the content of the polymer block (a) is 10% by mass or more, preferably 15% by mass or more, and more preferably 20% by mass or more, from the viewpoint of reducing the static friction coefficient.

[0076] When the content of the polymer block (a) mainly composed of vinyl aromatic monomer units is 10% by mass or more, the static friction coefficient can be reduced by reducing the stickiness of the hydrogenated block copolymer (a). In addition, the polishing pad of this embodiment has a tendency to reduce the static friction coefficient and exhibit stable dressing properties.

[0077] Furthermore, in the hydrogenated block copolymer (A), the content of the polymer block (a) is preferably 50% by mass or less, more preferably 48% by mass or less, further preferably 46% by mass or less, and even more preferably 45% by mass or less.

[0078] When the content of the polymer block (a) mainly composed of vinyl aromatic monomer units in the hydrogenated block copolymer (A) is 50 mass % or less, the polishing pad of this embodiment has improved adhesion to the workpiece and can exhibit high planarization performance in the polishing step.

[0079] The content of the polymer block (a) in the hydrogenated block copolymer (A) can be measured by a method using a nuclear magnetic resonance apparatus (NMR) (the method described in Y. Tanaka, et al., RUBBER CHEMISTRY and TECHNOLOGY 54, 685 (1981), hereinafter referred to as "NMR method") using the block copolymer before hydrogenation or the hydrogenated block copolymer after hydrogenation as an analyte.

[0080] The content of the polymer block (a) in the hydrogenated block copolymer (A) can be controlled within the above-mentioned numerical range by adjusting mainly the amount of the vinyl aromatic compound added to the polymerization reactor, the reaction temperature, and the reaction time.

[0081] <Hydrogenated Copolymer Block (b)>

[0082] The content of the polymer block (b) in the hydrogenated block copolymer (A) is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more.

[0083] When the content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b) is 40% by mass or more, the wear resistance of the polishing pad of the present embodiment can be improved during the polishing step, thereby maintaining a high polishing rate for a long period of time.

[0084] The hydrogenated block copolymer (a) used in the polishing pad of the present embodiment preferably contains at least one hydrogenated copolymer block (b) composed of a vinyl aromatic monomer unit and a conjugated diene monomer unit.

[0085] The content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b) is preferably 5% by mass or more, more preferably 15% by mass or more, further preferably 30% by mass or more, and particularly preferably 45% by mass or more.

[0086] When the content of the vinyl aromatic monomer units in the hydrogenated copolymer block (b) is 5% by mass or more, the polishing pad of this embodiment can maintain a high polishing rate for a long period of time during the polishing step by improving the wear resistance of the polishing pad.

[0087] The content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b) is preferably 79% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less.

[0088] When the content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b) is 79% by mass or less, the polishing pad of the present embodiment has improved adhesion to the workpiece, and can exhibit high planarization performance in the polishing step.

[0089] The content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b) can be measured by a nuclear magnetic resonance apparatus (NMR) or the like.

[0090] The content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b) can be controlled within the above numerical range by adjusting the amount of the vinyl aromatic compound and conjugated diene added to the polymerization reactor, the reaction temperature, and the like.

[0091] <Weight Average Molecular Weight of Hydrogenated Block Copolymer (A)>

[0092] The hydrogenated block copolymer (A) used in the polishing pad of this embodiment preferably has a weight average molecular weight (Mw) of 10,000 or more, more preferably 30,000 or more, and even more preferably 50,000 or more, from the perspectives of extrusion moldability during pellet production of the hydrogenated block copolymer (A) and obtaining good mechanical strength and low stickiness in the polishing pad of this embodiment.

[0093] The upper limit is preferably 400,000 or less, more preferably 300,000 or less, and even more preferably 250,000 or less. When the weight average molecular weight (Mw) is 300,000 or less, the hydrogenated block copolymer (A) tends to melt easily during pellet production (extrusion molding), resulting in stable strands and improved extrusion moldability.

[0094] The weight average molecular weight of the hydrogenated block copolymer (A) can be determined by gel permeation chromatography (GPC) using a calibration curve obtained by measurement of commercially available standard polystyrene (created using the peak molecular weight of the standard polystyrene).

[0095] <Molecular Weight Distribution (Mw / Mn) of Hydrogenated Block Copolymer (A)>

[0096] The molecular weight distribution (Mw / Mn) of the hydrogenated block copolymer (A) used in the polishing pad of this embodiment is not particularly limited. However, from the perspective of processability, it is preferably 10 or less, more preferably 3 or less, and even more preferably 1.5 or less. From the perspective of processability, the lower limit of Mw / Mn is preferably 1 or more, more preferably 1.005 or more, and even more preferably 1.01 or more.

[0097] The weight average molecular weight (Mw) and number average molecular weight (Mn) of the hydrogenated block copolymer (A) can be determined by gel permeation chromatography (GPC) using a calibration curve obtained by measurement using commercially available standard polystyrene (created using the peak molecular weight of the standard polystyrene) to determine the peak molecular weight of the chromatogram. The molecular weight distribution (Mw / Mn) of the hydrogenated block copolymer (A) can be determined from the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn).

[0098] <Hydrogenation Ratio of Double Bonds of Conjugated Diene Monomer Units in Hydrogenated Block Copolymer (A)>

[0099] The hydrogenation rate of the double bonds of the conjugated diene monomer units in the hydrogenated block copolymer (A) used in the polishing pad of this embodiment is not particularly limited, but is preferably 30% or more, more preferably 50% or more, further preferably 85% or more, and further preferably 92% or more, from the perspective of obtaining good heat resistance.

[0100] The hydrogenation rate of the double bonds of the conjugated diene monomer units in the hydrogenated block copolymer (A) can be controlled within the above numerical range by adjusting the amount of hydrogenation. The hydrogenation rate of the hydrogenated block copolymer (A) can be measured using a nuclear magnetic resonance apparatus (NMR) or the like.

[0101] <Structure of Hydrogenated Block Copolymer (A)>

[0102] (Structure of hydrogenated block copolymer (A))

[0103] The structure of the hydrogenated block copolymer (A) according to the present embodiment is not particularly limited, and examples thereof include a structure represented by the following general formula.

[0104] aba, (ab) n-X 、c-(ba) n 、c-(ab) n 、c-(aba) n 、c-(bab) n 、c-(bca) n 、a-(cbca) n 、ac-(ba) n 、ac-(ab) n 、ac-(ba) n -b,ca-(ba) n -c, ac-(ba) n -c, ab-(ca) n -b, ac-(bc) n -ac, c-(abc)n -ac、a-(cb) n -ca、c-(ac) n -bcac, [(abc) n ] m -X, [a-(bc) n ] m -X, [(ab) n -c] m -X, [(aba) n -c] m -X, [(bab) n -c] m -X, [(cba) n ] m -X, [c-(ba) n ] m -X, [c-(aba) n ] m -X, [c-(bab) n ] m -X

[0105] It should be noted that in the above general formulas, a represents a polymer block (a) mainly composed of vinyl aromatic monomer units, b represents a hydrogenated copolymer block (b) composed of vinyl aromatic monomer units and conjugated diene monomer units, and c represents a hydrogenated polymer block (c) mainly composed of conjugated diene monomer units.

[0106] n is an integer of 1 or greater, and preferably an integer of 1-5.

[0107] m is an integer of 2 or greater, and preferably an integer of 2-11.

[0108] X represents the residue of a coupling agent or the residue of a polyfunctional initiator.

[0109] <Static Friction Coefficient of Hydrogenated Block Copolymer (A)>

[0110] The static friction coefficient of the hydrogenated block copolymer (A) used in the polishing pad of this embodiment is preferably 2.5 or less, more preferably 2 or less, and even more preferably 1.7 or less, from the viewpoint of reducing the static friction coefficient of the polishing pad.

[0111] As an example of the method for reducing the static friction coefficient, a method for reducing stickiness can be cited, for example, in the above-mentioned (ab) n-XIn polymer polymerization, methods such as reducing the unreacted components during the coupling reaction of the diblock polymer, reducing the amount of vinyl bonds in all conjugated diene monomer units in the hydrogenated block copolymer (a), and increasing the content of the polymer block (a) mainly composed of vinyl aromatic monomer units in the hydrogenated block copolymer (a) can be mentioned.

[0112] The static friction coefficient can be measured in accordance with JIS K 7125.

[0113] <Dynamic Friction Coefficient of Hydrogenated Block Copolymer (A)>

[0114] The dynamic friction coefficient of the hydrogenated block copolymer (A) used in the polishing pad of this embodiment is preferably 1 or less, more preferably 0.8 or less, and even more preferably 0.5 or less, from the viewpoint of reducing the dynamic friction coefficient of the polishing pad.

[0115] Examples of methods for reducing the dynamic friction coefficient include a method of reducing the static friction coefficient and a method of increasing the content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b).

[0116] The dynamic friction coefficient can be measured in accordance with JIS K 7125.

[0117] <Hardness of Hydrogenated Block Copolymer (A)>

[0118] The instantaneous hardness of the hydrogenated block copolymer (A), as measured using a type A durometer in accordance with JIS K6253, is preferably 60 or greater, more preferably 70 or greater, further preferably 80 or greater, and even more preferably 85 or greater, from the perspective of suppressing edge sagging of a semiconductor during semiconductor polishing when used in a polishing pad.

[0119] In order to suppress scratches on the base when used in a polishing pad, the instantaneous hardness value measured with a type D durometer in accordance with JIS K6253 is preferably 70 or less, more preferably 60 or less, and even more preferably 50 or less.

[0120] The hardness of the hydrogenated block copolymer (A) can be controlled within the above-mentioned numerical range by adjusting the weight average molecular weight of the hydrogenated block copolymer (A), the content of the polymer block (a), the content of the vinyl aromatic monomer units in the hydrogenated copolymer block (b), the content of the hydrogenated polymer block (c), the amount of vinyl bonds in the conjugated diene monomer units, and the hydrogenation rate of the double bonds in the conjugated diene monomer units.

[0121] Furthermore, the hardness can be controlled within the above-mentioned numerical range by using a predetermined adjusting agent (which adjusts the vinyl bond content of the hydrogenated copolymer block (b), the content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b), and the copolymerizability between the vinyl aromatic compound and the conjugated diene) and conducting a polymerization reaction under the conditions described below. This can adjust the tan δ peak temperature (loss tangent) at -25°C to 60°C in the viscoelasticity measurement spectrum of the hydrogenated block copolymer (a), that is, the glass transition temperature derived from the hydrogenated copolymer block (b).

[0122] For example, increasing the content of polymer block (a) in the hydrogenated block copolymer (a), increasing the content of vinyl aromatic monomer units in the hydrogenated copolymer block (b), decreasing the content of hydrogenated polymer block (c), decreasing the hydrogenation rate of double bonds in the conjugated diene monomer units, and increasing the tan δ peak temperature (°C) at -20°C to 60°C tend to increase the hardness of the hydrogenated block copolymer (a). Furthermore, increasing the content of vinyl aromatic monomer units in the hydrogenated copolymer block (b) and increasing the vinyl bond content in the hydrogenated copolymer block (b) are particularly effective in increasing the tan δ peak temperature (°C) at -20°C to 60°C. Furthermore, the tan δ peak temperature (°C) can also be controlled by adjusting the copolymerizability of the vinyl aromatic compound and the conjugated diene by adjusting the polymerization conditions described below.

[0123] (Tan δ (Loss Tangent) Peak Temperature in Viscoelasticity Measurement Spectrum of Hydrogenated Block Copolymer (A))

[0124] In the hydrogenated block copolymer (A) of the present embodiment, the peak of tan δ (loss tangent) in the viscoelasticity measurement spectrum preferably exists at least one at -25°C to 60°C. More preferably, the peak exists at -15°C to 50°C, further preferably at -5°C to 40°C, and even more preferably at 0°C to 30°C.

[0125] The tan δ peak is derived from the hydrogenated copolymer block (b) in the hydrogenated block copolymer (a). In order to improve the planarization performance of the polishing pad during polishing, it is preferred that at least one peak be present in the range of -25°C to 60°C.

[0126] As described above, the hydrogenated copolymer block (b) is obtained by hydrogenating a copolymer block composed of a conjugated diene monomer unit and a vinyl aromatic monomer unit.

[0127] In the hydrogenated block copolymer (A) of the present embodiment, in order to allow at least one tan δ (loss tangent) peak to exist in the range of -25°C to 60°C, it is effective to control the conjugated diene monomer unit / vinyl aromatic monomer unit (mass ratio). The conjugated diene monomer unit / vinyl aromatic monomer unit (mass ratio) is preferably 79 / 21 to 16 / 84, more preferably 75 / 35 to 18 / 82, and even more preferably 70 / 30 to 25 / 75.

[0128] In order to ensure that at least one tan δ (loss tangent) peak exists in the range of 0°C to 30°C, it is effective to control the conjugated diene monomer unit / vinyl aromatic monomer unit (mass ratio). The conjugated diene monomer unit / vinyl aromatic monomer unit (mass ratio) is preferably 65 / 35 to 16 / 84, more preferably 60 / 40 to 25 / 75, and even more preferably 55 / 45 to 30 / 70.

[0129] In order to obtain a hydrogenated block copolymer (a) having at least one tan δ (loss tangent) peak in the range of -25°C to 60°C, a polymerization reaction is carried out under the conditions described below using a predetermined adjusting agent (which adjusts the vinyl bond content of the hydrogenated copolymer block (b), the content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b), and the copolymerizability of the vinyl aromatic compound and the conjugated diene), and the resulting block copolymer is hydrogenated.

[0130] The tan δ of the hydrogenated block copolymer (A) can be measured using a viscoelasticity measuring apparatus (ARES, manufactured by TA Instruments Co., Ltd.) under the conditions of a strain of 0.5%, a frequency of 1 Hz, and a heating rate of 3° C. / min.

[0131] (Method for producing hydrogenated block copolymer composition)

[0132] The hydrogenated block copolymer composition constituting the raw material of the polishing pad of the present embodiment can be produced by a conventionally known method.

[0133] The hydrogenated block copolymer composition of the present embodiment can be produced by, but is not limited to, the following methods: a method of melt-kneading the components (the hydrogenated block copolymer (A) described above, the polyolefin-based resin (B) described below, and other additives as necessary) using a mixer such as a Banbury mixer, a single-screw extruder, a twin-screw extruder, a worm kneader, or a multi-screw extruder; a method of dissolving or dispersing the components and then heating to remove the solvent; and the like.

[0134] In particular, a melt kneading method using an extruder is suitable from the viewpoint of productivity and good kneading properties.

[0135] The hydrogenated block copolymer composition may be in any shape, but is not limited to, pellets, sheets, strands, chips, etc. Alternatively, a molded article may be produced directly after melt kneading.

[0136] (Hardness of Hydrogenated Block Copolymer Composition)

[0137] The hardness of the hydrogenated block copolymer composition constituting the raw material of the polishing pad of this embodiment is preferably 60 or greater, more preferably 70 or greater, even more preferably 80 or greater, and even more preferably 85 or greater, from the perspective of suppressing edge sagging of the semiconductor during polishing of the semiconductor when used in the polishing pad.

[0138] In order to suppress scratches on the base when used in a polishing pad, the instantaneous hardness value measured with a type D durometer in accordance with JIS K6253 is preferably 70 or less, more preferably 60 or less, and even more preferably 50 or less.

[0139] The hardness of the hydrogenated block copolymer composition can be controlled by adjusting the hardness of the hydrogenated block copolymer (A), the flexural modulus of the component (B), and the composition ratio of the components (A) to (B) contained in the hydrogenated block copolymer composition.

[0140] (Static Friction Coefficient of Hydrogenated Block Copolymer Composition)

[0141] The static friction coefficient of the hydrogenated block copolymer composition used in the polishing pad of the present embodiment is preferably 2.5 or less, more preferably 2 or less, and even more preferably 1.7 or less, from the viewpoint of reducing the static friction coefficient of the polishing pad.

[0142] As a method for reducing the static friction coefficient, in addition to the method of reducing the static friction coefficient of the hydrogenated block copolymer (A) itself, the addition of an olefin-based resin (B) can be mentioned.

[0143] The static friction coefficient can be measured in accordance with JIS K 7125.

[0144] (Dynamic Friction Coefficient of Hydrogenated Block Copolymer Composition)

[0145] The static friction coefficient of the hydrogenated block copolymer composition used in the polishing pad of the present embodiment is preferably 1 or less, more preferably 0.8 or less, and even more preferably 0.5 or less, from the viewpoint of reducing the dynamic friction coefficient of the polishing pad.

[0146] As a method for reducing the dynamic friction coefficient, in addition to a method of reducing the static friction coefficient of the hydrogenated block copolymer (A) itself, there is also a method of adding an olefin-based resin (B).

[0147] The dynamic friction coefficient can be measured in accordance with JIS K 7125.

[0148] <Olefin Resin (II)>

[0149] The hydrogenated block copolymer composition constituting the foam of the present embodiment contains an olefin-based resin (II).

[0150] Examples of the olefin resin (ethylene) used in the foam of the present embodiment include, but are not limited to, polyethylene (PE), polypropylene (PP), 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 4-methyl-1-pentene, 1-octene, and the like. α - Olefin homopolymers. Random copolymers or block copolymers formed from combinations of olefins selected from ethylene, propylene, butene, pentene, hexene, octene, etc. may also be mentioned.

[0151] Specifically, ethylene and / or propylene-α-olefin copolymers such as ethylene-propylene copolymers, ethylene-1-butene copolymers, ethylene-3-methyl-1-butene copolymers, ethylene-4-methyl-1-pentene copolymers, ethylene-1-hexene copolymers, ethylene-1-octene copolymers, ethylene-1-decene copolymers, propylene-1-butene copolymers, propylene-1-hexene copolymers, propylene-1-octene copolymers, propylene-4-methyl-1-pentene copolymers, ethylene-propylene-1-butene copolymers, propylene-1-hexene-ethylene copolymers, and propylene-1-octene-ethylene copolymers can be cited.

[0152] Furthermore, the copolymers with ethylene and / or propylene also include copolymers with unsaturated monomers other than the above-mentioned α-olefins.

[0153] Examples of the above-mentioned copolymers with other unsaturated monomers include, but are not limited to, copolymers of ethylene and / or propylene with unsaturated organic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, methyl acrylate, methyl methacrylate, maleic anhydride, arylmaleimide, alkylmaleimide, or their derivatives; copolymers of ethylene and / or propylene with vinyl esters such as vinyl acetate; and copolymers of ethylene and / or propylene with non-conjugated dienes such as dicyclopentadiene, 4-ethylidene-2-norbornene, 4-methyl-1,4-hexadiene, and 5-methyl-1,4-hexadiene.

[0154] From the perspectives of economic efficiency and good compatibility in the hydrogenated block copolymer composition constituting the foam of the present embodiment to achieve high transparency, the (ethylene)olefin-based resin preferably contains at least one polypropylene-based resin.

[0155] In addition, the olefin-based resin (II) may be modified with a predetermined functional group.

[0156] The functional group is not particularly limited, and examples thereof include an epoxy group, a carboxyl group, an acid anhydride group, and a hydroxyl group.

[0157] The functional group-containing compound or modifier used to modify the olefin-based resin (II) is not particularly limited, but the following compounds can be mentioned.

[0158] Examples include unsaturated epoxides such as glycidyl methacrylate, glycidyl acrylate, vinyl glycidyl ether, and allyl glycidyl ether, and unsaturated organic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, allyl succinic acid, maleic anhydride, fumaric anhydride, and itaconic anhydride. Examples include, but are not particularly limited to, ionomers and chlorinated polyolefins.

[0159] From the perspectives of economy and good compatibility in the hydrogenated block copolymer composition constituting the foam of this embodiment to achieve high transparency, the olefin resin (B) is preferably a polypropylene resin such as a polypropylene homopolymer or an ethylene-propylene random or block copolymer.

[0160] In particular, ethylene-propylene random copolymers are more preferred from the viewpoints of transparency and flexibility.

[0161] The olefin-based resin (II) may be composed of a single material or a combination of two or more materials.

[0162] <Content of Component (A) in the Hydrogenated Block Copolymer Composition>

[0163] The content of the hydrogenated block copolymer (A) in the hydrogenated block copolymer composition constituting the polishing pad raw material of the present embodiment is 5% by mass or more, preferably 40% by mass or more, and more preferably 70% by mass or more, from the perspective of improving the polishing rate and planarization performance in the semiconductor polishing process when used as a polishing pad. It should be noted that the upper limit may be 100% by mass.

[0164] Furthermore, when the content of the hydrogenated block copolymer (A) in the hydrogenated block copolymer composition is 40% by mass or more, the polishing rate is further improved.

[0165] [Foam]

[0166] The polishing pad of this embodiment is preferably a foam.

[0167] In this embodiment, the foam contains cells.

[0168] By using the polishing pad of this embodiment as a foam, the value of the static friction coefficient can be easily adjusted to a predetermined range.

[0169] (Average cell diameter, distribution, and closed cell ratio of foam)

[0170] The average cell diameter of the foam used in the present embodiment is not particularly limited, but is preferably 20 to 500 μm, more preferably 30 to 300 μm, and particularly preferably 40 to 200 μm from the viewpoint of suppressing clogging of slurry particles and maintaining good particle retention.

[0171] The average cell diameter of the foam used in the present embodiment can be determined as the arithmetic mean of the cell diameters determined from the volumes of the individual cells described later.

[0172] The cell diameter distribution of the foam can be determined from a volume-based cell diameter distribution curve described later.

[0173] From the perspective of adjusting the static friction coefficient to fall within the above range, the difference between the cell diameter at a cumulative volume frequency of 80% and the cell diameter at a cumulative volume frequency of 20% is preferably 50 μm or more.

[0174] If the difference between the bubble diameter at the 80% cumulative volume frequency and the bubble diameter at the 20% cumulative volume frequency (bubble diameter at the 80% cumulative volume frequency minus bubble diameter at the 20% cumulative volume frequency) is large, the bubble diameters can be distributed over a relatively wide range, thereby reducing the static friction coefficient of the resulting polishing pad.

[0175] The closed cell ratio of the foam can be determined by measuring the closed cell ratio (%) of the foam in accordance with ASTM D 1940-62T. The closed cell ratio is not particularly limited, but is preferably 5% or more, more preferably 7% or more, and particularly preferably 10% or more from the perspective of maintaining good slurry particle retention.

[0176] The average cell diameter, distribution, and closed cell ratio of the foam used in the polishing pad can be adjusted by changing the amount of the foaming agent, the viscosity of the composition, and the foaming conditions.

[0177] The volume-based cell diameter distribution curve can be obtained as follows using an X-ray CT scanner (for example, TDM1000H-I manufactured by Yamato Science Co., Ltd.).

[0178] That is, the volume of each cell included in the measurement target range of the resin foam is measured, and the diameter of a true sphere having the same volume as the measured volume is determined as the diameter of each cell.

[0179] Here, the above-mentioned “average cell diameter” refers to the arithmetic mean value of the cell diameters obtained from the volumes of the individual cells [=total value of “cell diameters” / (number of cells)].

[0180] In addition, the volume-based distribution curve of the bubble diameters can be obtained based on the data of the number-based distribution curve of the bubble diameters.

[0181] That is, the number of bubbles can be calculated at regular intervals starting from the bubble diameter of 0 μm, and the "number of bubbles at each interval" can be used as the "number of bubbles at the upper limit of the bubble diameter at each interval" to calculate the distribution curve of the bubble diameter based on the number. Based on the data of the distribution curve of the bubble diameter based on the number, the total bubble volume can be calculated at regular intervals starting from the bubble diameter of 0 μm, and the "total bubble volume" can be used as the "volume at the upper limit of the bubble diameter at each interval" to calculate the distribution curve of the bubble diameter based on the volume.

[0182] In addition, from the viewpoint of determining the peak position with higher accuracy, the above-mentioned fixed interval is preferably set to 20 μm or less.

[0183] [Method for producing foam]

[0184] The method for producing the polishing pad foam of this embodiment is not particularly limited. For example, the following method is used: a foaming agent and a crosslinking agent are added to a hydrogenated block copolymer composition, melt-kneaded, and heated in a mold to form a foam. The foam can be cut into a desired size and used as a polishing pad.

[0185] The cross-linking agent used in this embodiment is not particularly limited. It is preferably a free radical initiator that has a decomposition temperature higher than the flow starting temperature of the resin used and is decomposed by heating to generate free radicals to generate cross-linking bonds between or within its molecules. Specifically, it includes organic peroxides such as diisopropyl benzene peroxide, 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, 2,5-dimethyl-2,5-di-tert-butylperoxyhexane, 2,5-dimethyl-2,5-di-tert-butylperoxyhexyne, α,α-di-tert-butylperoxydiisopropyl benzene, tert-butyl peroxide ketone, tert-butyl peroxybenzoate, etc. The best organic peroxide should be selected according to the type of resin used at this time.

[0186] The foaming agent is not particularly limited, and an inorganic foaming agent, an organic foaming agent, or a physical foaming agent can be used.

[0187] Examples of the inorganic foaming agent include, but are not limited to, sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, ammonium nitrite, azide compounds, sodium borohydride, aluminum acetate, and metal powder.

[0188] Examples of the organic foaming agent include, but are not limited to, azodicarboxamide, azobisformamide, azobisisobutyronitrile, barium azodicarboxylate, N,N'-dinitrosopentamethylenetetramine, N,N'-dinitroso-N,N'-dimethylterephthalamide, benzenesulfonylhydrazide, p-toluenesulfonylhydrazide, p,p'-oxybisbenzenesulfonylhydrazide, and p-toluenesulfonylsemicarbazide.

[0189] Examples of physical blowing agents include, but are not limited to, hydrocarbons such as pentane, butane, and hexane; halogenated hydrocarbons such as methyl chloride and dichloromethane; gases such as nitrogen, carbon dioxide, and air; and fluorinated hydrocarbons such as trichlorofluoromethane, dichlorodifluoromethane, trichlorotrifluoroethane, chlorodifluoroethane, and hydrofluorocarbons.

[0190] Furthermore, these foaming agents may be used in combination.

[0191] (foaming aid)

[0192] In the above-mentioned step of producing the foamed body, a foaming aid may be used together with the foaming agent.

[0193] The foaming aid is not particularly limited, and substances commonly used as foaming aids in the prior art can be used.

[0194] For example, zinc compounds such as urea compounds, zinc oxide, zinc stearate, zinc benzenesulfinate, zinc toluenesulfonate, zinc trifluoromethanesulfonate, and zinc carbonate; and lead compounds such as lead dioxide and trivalent lead.

[0195] (foaming nucleating agent)

[0196] A foaming nucleating agent may be used in the step of producing the foam.

[0197] The foaming nucleating agent is not particularly limited, and substances commonly used as foaming nucleating agents in the related art can be used.

[0198] Examples thereof include titanium oxide, talc, kaolin, clay, calcium silicate, silicon oxide, sodium citrate, calcium carbonate, diatomaceous earth, calcined pearlite, zeolite, bentonite, glass, limestone, calcium sulfate, aluminum oxide, titanium oxide, magnesium carbonate, sodium carbonate, iron carbonate, and polytetrafluoroethylene powder.

[0199] (Foaming ratio)

[0200] The expansion ratio of the foam used in this embodiment is not particularly limited, but is preferably 1.5 to 4 times, more preferably 1.7 to 3.5 times or more, and particularly preferably 2 to 3 times or more from the viewpoint of obtaining a good polishing rate.

[0201] The expansion ratio of the foam can be adjusted by changing the amount of the foaming agent, the viscosity of the composition, and the foaming conditions.

[0202] The shape of the polishing base of the polishing pad of this embodiment is not particularly limited, and may be, for example, a disk or a polygonal column, and can be appropriately selected according to the polishing apparatus in which the polishing pad of this embodiment is mounted and used.

[0203] The size of the polishing base is not particularly limited. For example, in the case of a disc-shaped polishing pad, the diameter may be 150 to 1200 mm, preferably 500 to 800 mm, and the thickness may be 1.0 to 5.0 mm, preferably 1.5 to 3.0 mm.

[0204] The polishing base of the polishing pad of this embodiment may have grooves on the polishing surface. The grooves have the following functions: retaining the aqueous dispersion supplied during polishing, distributing it more evenly on the polishing surface, and forming a path for temporarily retaining waste such as polishing debris and used aqueous dispersion and discharging it to the outside.

[0205] The shape of the groove is not particularly limited, and may be, for example, spiral, concentric, or radial.

[0206] In addition, the grinding base of the grinding pad of the present embodiment can have a recess on the non-grinding surface (back side). This recess has the following function: to relax the excessive stress of the local area that may be produced when grinding, and to more effectively suppress the generation of surface defects such as the scratches that are ground.

[0207] The shape of the recessed portion is not particularly limited, and may be, for example, circular, polygonal, spiral, concentric, radial, or the like.

[0208] In addition, the polishing pad of this embodiment may also have parts with other functions in addition to the polishing part. As parts with other functions, for example, a window part for detecting the end point using an optical end point detection device can be cited. As the window part, for example, the following materials can be used: when the thickness is 2 mm, the transmittance of light of any wavelength between 100 and 300 nm is preferably 0.1% or more, more preferably 2% or more; or the cumulative transmittance in any wavelength region between 100 and 300 nm is preferably 0.1% or more, more preferably 2% or more. The material of the window part is not particularly limited as long as it meets the above-mentioned optical properties. For example, the same composition as the above-mentioned polishing base can be used.

[0209] The manufacturing method of the grinding base constituting the grinding pad of the present embodiment is not particularly limited. In addition, the method for forming the grooves and recesses (hereinafter referred to as "grooves, etc.") that the grinding base may optionally have is also not particularly limited. For example, a chemical mechanical polishing pad composition constituting the grinding base of the grinding pad can be prepared in advance, and the composition can be formed into a rough shape of the desired shape, and then grooves, etc. can be formed by cutting. In addition, the grinding pad composition can be molded using a mold having a pattern constituting the grooves, etc. to form grooves, etc. simultaneously with the rough shape of the grinding base.

[0210] The method for obtaining the polishing pad composition is not particularly limited. For example, the necessary materials such as the prescribed organic material can be mixed using a mixing machine or the like. As the mixing machine, a conventionally known mixing machine can be used. For example, mixing machines such as a roller, a kneader, a Banbury mixer, and an extruder (single screw, multi-screw) can be mentioned.

[0211] The polishing pad of the present embodiment may be composed solely of the above-mentioned polishing base, or may be a multi-layered pad including a support layer on the non-polishing surface side of the above-mentioned polishing base.

[0212] The support layer is a layer that supports the grinding base on the back side of the grinding surface. The properties of the support layer are not particularly limited, but it is preferably softer than the material of the grinding base. By having a support layer of a softer material, even when the grinding base is thin, for example, less than 1.0 mm, it can prevent the grinding base from floating during grinding and the surface of the grinding layer from warping, thereby enabling stable grinding.

[0213] In addition, the supporting layer can be a porous body (foam) or a non-porous body. In addition, its planar shape is not particularly limited and can be the same as or different from the grinding layer. As the planar shape of the supporting layer, for example, it can be a circle, a polygon (quadrilateral, etc.), etc.

[0214] The thickness is also not particularly limited, and is preferably 0.1 to 5 mm, and more preferably 0.5 to 2 mm, for example.

[0215] The material constituting the support layer is not particularly limited, but an organic material is preferably used because it can be easily molded into a predetermined shape and properties and can impart appropriate elasticity.

[0216] The polishing pad of this embodiment as described above can suppress scratches on the polished surface and provide a high-quality polished surface.

[0217] The polishing pad may be one obtained by impregnating a nonwoven fabric substrate or a suede substrate with a solution of the hydrogenated block copolymer (A).

[0218] The fibers contained in the nonwoven fabric in the nonwoven fabric substrate are not particularly limited, and examples thereof include aromatic polyester fibers containing one or more of polyethylene terephthalate (PET), isophthalic acid-modified polyethylene terephthalate, sulfoisophthalic acid-modified polyethylene terephthalate, polybutylene terephthalate, and polyhexamethylene terephthalate; fibers containing polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene succinate / adipate-butylene terephthalate, and polyhydroxybutyrate-polyhydroxyvalerate copolymers. aliphatic polyester fibers comprising one or more of polyamide 6, polyamide 66, polyamide 10, polyamide 11, polyamide 12, and polyamide 6-12; polyolefin fibers comprising one or more of polypropylene, polyethylene, polybutene, polymethylpentene, and chlorinated polyolefins; modified polyvinyl alcohol fibers comprising modified polyvinyl alcohol containing 25 to 70 mol% of ethylene units; and elastic fibers comprising elastomers such as polyurethane elastomers, polyamide elastomers, and polyester elastomers. These may be used alone or in combination of two or more.

[0219] The solvent used for solution impregnation is not particularly limited, and examples thereof include methyl ethyl ketone (MEK); aliphatic hydrocarbons such as n-butane, isobutane, n-pentane, n-hexane, n-heptane, and n-octane; alicyclic hydrocarbons such as cyclohexane, cycloheptane, and methylcycloheptane; and aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene.

[0220] <Hardness of polishing pad>

[0221] From the perspective of suppressing the edge sagging of the semiconductor during semiconductor polishing when used as a polishing pad, the polishing pad has an instantaneous hardness value of 30C or more, more preferably 35C or more, further preferably 40C or more (equivalent to 20A), and even more preferably 45C or more (equivalent to 22A), as measured by a type A durometer in accordance with JIS K6253 or a spring-type ASKER C type durometer in accordance with SRIS 0101.

[0222] In addition, from the perspective of suppressing scratches on the base when used as a polishing pad, the instantaneous hardness value measured using a type A durometer or type D durometer in accordance with JIS K6253 is preferably 35D (equivalent to 90A) or less, more preferably 80A or less, and even more preferably 70A or less.

[0223] (Static friction coefficient of polishing pad)

[0224] The static friction coefficient of the polishing pad of this embodiment is 1.2 or less, more preferably 1.0 or less, and even more preferably 0.9 or less.

[0225] As a method for reducing the static friction coefficient, in addition to reducing the static friction coefficient of the hydrogenated block copolymer composition itself, there are also methods such as improving the cell diameter distribution and groove processing.

[0226] By setting the static friction coefficient of the polishing pad within the above range, stable dressing performance can be exhibited.

[0227] The static friction coefficient can be measured in accordance with JIS K 7125.

[0228] (Dynamic friction coefficient of polishing pad)

[0229] From the viewpoint of reducing the dynamic friction coefficient of the polishing pad, the static friction coefficient of the polishing pad of this embodiment is preferably 0.65 or less, more preferably 0.60 or less, and even more preferably 0.55 or less.

[0230] The method for reducing the dynamic friction coefficient includes, in addition to reducing the dynamic friction coefficient of the hydrogenated block copolymer composition itself, improving the cell diameter distribution, groove processing, and the like.

[0231] By setting the dynamic friction coefficient of the polishing pad within the above range, a high polishing rate can be maintained without wearing the polishing pad even when polishing a semiconductor or the like for a long period of time.

[0232] The dynamic friction coefficient can be measured in accordance with JIS K 7125.

[0233] The surface and / or back of the grinding layer can be subjected to a finishing process (grinding process). The method for finishing (grinding process) is not particularly limited and can be ground by known methods. Specifically, the grinding performed by a diamond dresser can be enumerated.

[0234] The polishing pad of this embodiment can be mounted on a commercially available polishing apparatus and used in a polishing step by a known method.

[0235] The polishing pad of this embodiment can be used in a wide range of polishing steps for manufacturing semiconductor devices.

[0236] The object to be polished that can be polished using the polishing pad of this embodiment is not particularly limited, and examples thereof include materials requiring flatness such as silicon wafers, glass, magnetic disks, sapphire, and semiconductors such as SiC and GaN. The method for manufacturing the polished object of this embodiment can be suitably used as a method for manufacturing semiconductors such as SiC and GaN.

[0237] The polishing slurry may contain water, chemical components such as oxidizing agents represented by hydrogen peroxide and potassium permanganate, additives, abrasives (abrasive particles; for example, SiC, SiO2, Al2O3, CeO2), etc., depending on the object to be polished, polishing conditions, etc.

[0238] The double-sided tape used to fix the polishing pad and the polishing machine is not particularly limited, and any known double-sided tape can be selected and used in the art.

[0239] Example

[0240] The present embodiment will be described in detail below with reference to specific examples and comparative examples, but the present embodiment is not limited to the following examples and comparative examples.

[0241] The measurement methods and evaluation methods of physical properties applied to Examples and Comparative Examples are as follows.

[0242] The structures of the hydrogenated block copolymers used in the foams of Examples and Comparative Examples were determined and their physical properties were measured as follows.

[0243] [Method for measuring the structure of hydrogenated block copolymer]

[0244] ((1) Content of all vinyl aromatic monomer units (styrene) in the hydrogenated block copolymer (A))

[0245] The content of all vinyl aromatic monomer units (styrene) in the hydrogenated block copolymer was measured using an ultraviolet spectrophotometer (UV-2450, manufactured by Shimadzu Corporation).

[0246] ((2) Hydrogenation Ratio of Double Bonds of Conjugated Diene Monomer Units in Hydrogenated Block Copolymer (A))

[0247] The hydrogenation rate of the double bonds in the conjugated diene monomer units was measured using a nuclear magnetic resonance apparatus (ECS400 manufactured by JEOL RESONANCE) using the hydrogenated block copolymer.

[0248] ((3) Content of Polymer Block (a) in Hydrogenated Block Copolymer (A))

[0249] The content of the polymer block (a) mainly composed of vinyl aromatic monomer units is measured using a hydrogenated block copolymer by nuclear magnetic resonance (NMR) (the method described in Y. Tanaka, et al., RUBBER CHEMISTRY and TECHNOLOGY 54, 685 (1981). Hereinafter referred to as "NMR method").

[0250] ((4) Content of the Hydrogenated Copolymer Block (b) in the Hydrogenated Block Copolymer (a))

[0251] The content of the hydrogenated copolymer block (a) can be calculated by the formula: 100 - (content of the hydrogenated copolymer block (a) in the hydrogenated block copolymer (a)).

[0252] ((5) Vinyl Bond Amount in Hydrogenated Block Copolymer (A))

[0253] The amount of vinyl bonds in the hydrogenated block copolymer was measured using a nuclear magnetic resonance apparatus (NMR).

[0254] The vinyl bond content in the conjugated diene monomer units in the hydrogenated block copolymer is determined from the ratio of the total area of the 1,2-bond and 3,4-bond peaks to the total area of all peaks (1,2-bond, 3,4-bond, and 1,4-bond) associated with the conjugated diene monomer units among the peaks obtained by NMR measurement.

[0255] ((6) Content of Vinyl Aromatic Monomer Units in the Hydrogenated Copolymer Block (b) Constituting the Hydrogenated Block Copolymer (a))

[0256] The content of the vinyl aromatic monomer units in the hydrogenated copolymer block (b) relative to the entire polymer is calculated based on the difference between the content of all vinyl aromatic monomer units in the hydrogenated block copolymer (a) measured in (1) above and the content of the polymer block (a) mainly composed of vinyl aromatic monomer units in the hydrogenated block copolymer (a) measured in (3) above. The content of the vinyl aromatic monomer units in the hydrogenated copolymer block (b) is calculated based on the ratio to the content of the hydrogenated copolymer block (b) in the hydrogenated block copolymer (a) measured in (4) above.

[0257] [Methods for measuring physical properties of hydrogenated block copolymers]

[0258] ((1) Hardness)

[0259] In accordance with JIS K6253, the values at 0 seconds and 15 seconds were measured using a type A durometer and a type D durometer, respectively.

[0260] The probe of the hardness tester was placed above and below the sample for measurement, and the hardness values at 0 seconds and 15 seconds were measured.

[0261] In the following table, hardness (JIS-A, 0 seconds), hardness (JIS-A, 15 seconds), hardness (JIS-D, 0 seconds), and hardness (JIS-D, 15 seconds) are respectively described.

[0262] Regarding the hardness value, when the hardness is less than 20 on the Type D durometer, the value on the Type A durometer is used, and when the hardness is greater than 90 on the Type A durometer, the value on the Type D durometer is used.

[0263] As a guideline, a hardness of 94 on a Type A durometer is equivalent to a hardness of 45 on a Type D durometer.

[0264] ((2) Melt flow rate (MFR, unit: g / 10 min))

[0265] The MFR was measured in accordance with JIS K7210 at a temperature of 230° C. and a load of 2.16 kg.

[0266] ((3) Static friction coefficient)

[0267] In accordance with JIS K7125, hydrogenated block copolymers (A)-1 to (B)-4 were used as raw materials. A brass specimen with a contact surface size of 63 mm x 63 mm and a load of 200 g was placed on a 2 mm pressure device fabricated by the method described below. The test was initiated within 3 seconds, and the brass specimen was moved parallel to the test piece at a test speed of 100 mm / min. The static friction coefficient was calculated by dividing the test force required to initiate movement of the test piece by the contact area.

[0268] ((4) Dynamic friction coefficient)

[0269] The test was conducted in accordance with JIS K7125 using the same method as (3). The coefficient of kinetic friction was obtained by dividing the average test force at the time when the test piece started to move and the test force stabilized by the contact area.

[0270] [Method for measuring physical properties of polishing pad]

[0271] ((1) Average bubble diameter)

[0272] The volume of each bubble within the polishing pad is measured using an X-ray CT scanner (e.g., TDM1000H-I manufactured by Yamato Science Co., Ltd.). The diameter of each bubble is determined by the diameter of a perfect sphere having the same volume as the measured volume. The arithmetic mean of the bubble diameters calculated from the volume of each bubble [= total value of "bubble diameters" / (number of bubbles)] is taken as the average bubble diameter.

[0273] ((2) Bubble diameter distribution)

[0274] An X-ray CT scanner (e.g., TDM1000H-I manufactured by Yamato Science Co., Ltd.) is used to obtain a volume-based distribution curve of the bubble diameters of the bubbles in the polishing pad. When the difference between the bubble diameter at a cumulative volume frequency of 80% and the bubble diameter at a cumulative volume frequency of 20% (bubble diameter at a cumulative volume frequency of 80% - bubble diameter at a cumulative volume frequency of 20%) is 50 μm or more, the bubble diameter distribution is judged to be wide. When the difference is less than 50 μm, the bubble diameter distribution is judged to be narrow.

[0275] ((3) Static friction coefficient))

[0276] Using the prepared polishing pad, the static friction coefficient of the hydrogenated block copolymer was measured by the same method as that of the hydrogenated block copolymer.

[0277] ((4) Dynamic friction coefficient)

[0278] The produced polishing pad was used to measure the dynamic friction coefficient of the hydrogenated block copolymer by the same method as that used for the measurement.

[0279] (5) Repairability

[0280] After affixing double-sided tape DF8391S manufactured by Toyochem to the polishing pad, the polishing pad was fixed to the platen of a 15-inch single-sided polishing machine (manufactured by Hitechnoth) and subjected to dressing at a platen speed of 60 rpm using a metal bond SD#270. The case where the friction force was too high and dressing was impossible was evaluated as dressing property B, and the case where dressing was possible was evaluated as dressing property A.

[0281] (6) Grinding rate

[0282] After the polishing pad was dressed for 1 hour by the method (5), a polishing test was performed under the conditions shown in Table 1 below.

[0283] It should be noted that the 4-inch SiC bases used for polishing were each processed in advance to make the surface roughness of the base uniform before use.

[0284] [Table 1]

[0285] project Implementation conditions Device 15-inch single-side grinding machine (Hitechnoth, fixed plate diameter 380Φ380Φ) Grinding body Φ4 inch SiC substrate 4H N 4off Si test wafer level slurry COMPOL 202SC (permanganate-based) manufactured by FUJIMI Incorporated Load (surface pressure) <![CDATA[15kg(160g / cm 2 )]]> Speed 60rpm Grinding time 15 minutes Slurry supply Dropper bottle one-way mode 4mL / min Cooler set temperature 25℃

[0286] ((7) Polishing rate stability (durability))

[0287] The polishing rate V0 immediately after the start of polishing was compared with the polishing rate V1 10 minutes after the start. The case where (V1 / V0)×100 was 70 or more was evaluated as A, the case where it was 50 to less than 70 was evaluated as B, the case where it was 30 to less than 50 was evaluated as C, and the case where it was less than 30 was evaluated as D.

[0288] (Production of Hydrogenated Block Copolymer (A))

[0289] <Preparation of Hydrogenation Catalyst>

[0290] In the Examples and Comparative Examples described below, the hydrogenation catalyst used in producing the hydrogenated block copolymer was prepared by the following method.

[0291] A reaction container equipped with a stirrer was purged with nitrogen, and 1 liter of dried and purified cyclohexane was added thereto.

[0292] Then, 100 mmol of bis(η5-cyclopentadienyl)titanium dichloride was added.

[0293] While the mixture was thoroughly stirred, a n-hexane solution containing 200 mmol of trimethylaluminum was added, and the mixture was reacted at room temperature for about 3 days to obtain a hydrogenation catalyst.

[0294] <Production Example 1: Hydrogenated Block Copolymer (A)-1>

[0295] Batch polymerization was carried out using a tank-type reactor (internal volume 10 L) equipped with a stirring device and a jacket.

[0296] First, a cyclohexane solution containing 15 parts by mass of styrene (concentration: 20% by mass) was added.

[0297] Next, 0.107 parts by mass of n-butyllithium per 100 parts by mass of all monomers and 0.9 mol of N,N,N',N'-tetramethylethylenediamine (hereinafter referred to as "TMEDA") per 1 mol of n-butyllithium were added, and polymerization was carried out at 65°C for 1 hour.

[0298] Next, a cyclohexane solution containing 29 parts by mass of butadiene and 41 parts by mass of styrene (concentration: 20% by mass) was added, and polymerization was carried out at 80°C for 2 hours. Finally, a cyclohexane solution containing 15 parts by mass of styrene (concentration: 20% by mass) was added, and polymerization was carried out at 65°C for 1 hour. Methanol was then added to terminate the polymerization reaction.

[0299] The block copolymer obtained as described above had a styrene content of 71% by mass, a polystyrene block content of 30% by mass, a vinyl bond content of 46% by mass, and a weight-average molecular weight of 60,000.

[0300] Furthermore, 100 ppm of the hydrogenation catalyst prepared as described above was added to the obtained block copolymer based on Ti per 100 parts by mass of the block copolymer, and a hydrogenation reaction was carried out under the conditions of a hydrogen pressure of 0.7 MPa and a temperature of 65°C.

[0301] Next, 0.3 parts by mass of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was added as a stabilizer based on 100 parts by mass of the block copolymer to obtain hydrogenated block copolymer (A)-1.

[0302] The hydrogenation rate of the obtained hydrogenated block copolymer (A)-1 was 98%. Other physical properties are shown in Table 2.

[0303] <Production Examples 2 to 7: Hydrogenated Block Copolymers (A)-2 to (A)-7>

[0304] In the method for producing the hydrogenated block copolymer (A)-1, the polymerization method and hydrogenation conditions were adjusted to produce (A)-2 to (A)-7. The physical properties are shown in Tables 2 and 3 below.

[0305] [Production of compression molded sheets]

[0306] The hydrogenated block copolymers (A)-1 to (A)-7 prepared as described above were individually rolled using a 4-inch roll at 160°C and then subjected to a hydraulic press at 200°C and 100 kg / cm 2 The molding was carried out under the conditions of , and a molding piece with a size of 130 mm × 220 mm and a thickness of 2 mm was produced.

[0307] [Production of Hydrogenated Block Copolymer Composition]

[0308] A hydrogenated block copolymer composition was produced using the above-mentioned hydrogenated block copolymers (A)-1 to (A)-7 and the following component (B).

[0309] (Olefin resin (II))

[0310] <Component (B)-1>

[0311] Olefin resin: Low-density polyethylene resin, L2340 (manufactured by Asahi Kasei Corporation)

[0312] [Production of Raw Materials and Hydrogenated Block Copolymer Composition Used in Example 2]

[0313] The pelletized hydrogenated block copolymer (A)-1 and the olefin resin (B) were mixed in the ratio (parts by mass) shown in Table 3 below, and kneaded using a twin-screw extruder (TEX-30) to form pellets, thereby obtaining a hydrogenated block copolymer composition.

[0314] The extrusion conditions were a barrel temperature of 230°C and a screw speed of 300 rpm.

[0315] [Manufacturing of polishing pad]

[0316] As shown in Examples 1 to 9, hydrogenated block copolymers (A)-1 to (A)-7 were used to manufacture a foam having a foaming ratio of 2.7 times using a known method according to the ratio shown in Table 3. The foam was cut into a cylindrical shape with an inner diameter of 400 mm and a thickness of 2 mm to make a polishing pad.

[0317] As shown in Comparative Examples 1 and 2, a foam having an expansion ratio of 2.7 was produced using hydrogenated block copolymer (A)-2 or olefin resin (B) according to the ratios shown in Table 3 using a known method. The foam was then cut into cylindrical shapes with an inner diameter of 400 mm and a thickness of 2 mm to produce polishing pads. In Comparative Example 1, the cell diameter was controlled by controlling the conditions.

[0318] The physical properties of the hydrogenated block copolymer (A) are shown in Table 2 below, and the evaluation results of the physical properties and characteristics of the polishing pad are shown in Table 3 below.

[0319]

[0320]

Claims

1. A polishing pad comprising 5% by mass or more of a hydrogenated block copolymer (A) satisfying the following conditions (1) to (2), wherein the static friction coefficient measured in accordance with JIS K 7125 is 1.2 or less, <Condition (1)>: The hydrogenated block copolymer (A) is a hydrogenated product of a block copolymer containing vinyl aromatic monomer units and conjugated diene monomer units. <Condition (2)>: The hydrogenated block copolymer (A) contains at least one polymer block (a) mainly composed of vinyl aromatic monomer units. The content of the polymer block (a) mainly composed of vinyl aromatic monomer units in the hydrogenated block copolymer (A) is 10% by mass or more.

2. The polishing pad according to claim 1, wherein The hydrogenated block copolymer (a) contains at least one hydrogenated copolymer block (b) composed of vinyl aromatic monomer units and conjugated diene monomer units, The content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b) is 5% by mass or more and 79% by mass or less.

3. The polishing pad according to claim 2, wherein The content of the vinyl aromatic monomer unit in the hydrogenated copolymer block (b) is 45% by mass or more and 79% by mass or less. The polishing pad according to claim 1 , comprising 40% by mass or more of the hydrogenated block copolymer (A). The polishing pad according to claim 1 , comprising 70% by mass or more of the hydrogenated block copolymer (A).

6. The polishing pad according to claim 1, wherein The value of the dynamic friction coefficient measured in accordance with JIS K 7125 is 0.6 or less.

7. The polishing pad according to claim 1, wherein The content of the polymer block (a) mainly composed of vinyl aromatic monomer units in the hydrogenated block copolymer (A) is 15% by mass or more and 40% by mass or less.

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