CN109957088B

CN109957088B - Polishing pad

Info

Publication number: CN109957088B
Application number: CN201811581083.2A
Authority: CN
Inventors: 小田善之; 柴雄一郎
Original assignee: DIC Corp
Current assignee: DIC Corp
Priority date: 2017-12-26
Filing date: 2018-12-24
Publication date: 2022-04-26
Anticipated expiration: 2038-12-24
Also published as: JP7259311B2; TWI787420B; JP2019116616A; CN109957088A; TW201930382A

Abstract

The invention provides a polishing pad having a high polishing rate and capable of obtaining an object to be polished with excellent high flatness (less edge rounding) and a urethane resin composition for use therein. A polishing pad used in the present invention is a cured product of a urethane resin composition containing a main agent (i) containing a urethane prepolymer (A) and a curing agent (ii), wherein the urethane prepolymer (A) is a product obtained after a reaction of a composition containing a polyol component (a) containing a polyol (a1) having a molecular weight of 300 or more and a short-chain diol (a2) having a molecular weight of less than 300 and a polyisocyanate (b), and has an isocyanate group at a terminal, the polyol component (a) contains 40 to 90 mass% of a polytetramethylene glycol and 1 mass% or more of a short-chain diol (a2), the cured product has a peak value of tan delta in a range of 120 ℃ to 200 ℃ inclusive, and the peak value of tan delta in the range of 120 ℃ to 200 ℃ inclusive is 0.18 or more.

Description

Polishing pad

Technical Field

The present invention relates to a polishing pad and a urethane resin composition for a polishing pad.

Background

The present invention particularly relates to a polishing pad which can be preferably used in polishing of optical lenses, glass substrates, silicon wafers, semiconductor devices, and the like, a method for producing the polishing pad, and a polishing method.

High levels of polishing efficiency or non-scratch property are required in optical lenses, glass substrates for Liquid Crystal Displays (LCDs), glass substrates for Hard Disk Drives (HDDs), silicon wafers, semiconductor devices, and the like.

In particular, in the semiconductor device, with the rapid increase in the integration degree of the semiconductor circuit, miniaturization and multilayer wiring for the purpose of high density have been advanced, and further higher level of surface flatness of the processed surface and high polishing efficiency have been required. In addition, the glass substrate for liquid crystal displays is also required to have a higher level of surface flatness of a processed surface and a high polishing efficiency in accordance with the increase in size of the liquid crystal display. The surface flatness of the processed surface is required to be improved to a high level, and further, required performance such as polishing efficiency in polishing is further improved.

Therefore, in the manufacturing process of optical lenses, semiconductor devices, or LCDs, as a polishing method capable of forming a surface having excellent flatness, a chemical Mechanical polishing method, so-called cmp (chemical Mechanical polishing) method, is widely used.

In the CMP method, a free abrasive particle system is generally adopted in which slurry (polishing liquid) in which abrasive particles (abrasive particles) are dispersed in an alkaline solution or an acid solution is supplied to perform polishing during polishing. That is, the (machined surface of the) object to be polished is planarized by the mechanical action of the abrasive grains in the slurry and the chemical action of the alkaline solution or the acid solution. Here, as the flatness required for the processed surface is increased, the requirements for polishing performance such as polishing precision and polishing efficiency, specifically, high polishing rate, non-scratch property, and high flatness required for the CMP method are increased. As a free abrasive type polishing pad using the CMP method, for example, a polishing pad having a high polishing rate, in which scratches are not easily generated by controlling specific parameters such as hardness, wear, relaxation time, and elastic coefficient, has been proposed (see patent documents 1 and 2).

In addition, for example, a urethane polishing pad having a specific composition such as ethylene glycol monophenyl ether is excellent in dressing (dressing) property (shear rate) (see patent document 3). Further, for example, a urethane polishing pad having a macroscopically phase-separated structure formed by utilizing compatibility between a polyester polyol and a polyether polyol as raw materials to be used has a high polishing rate and excellent stability (see patent documents 4 and 5).

For example, a polishing pad having a raw material composition defined for a specific bubble diameter or storage modulus has a high polishing rate and an excellent break-in time (see patent document 6).

As described above, a polishing pad having a high polishing rate, a low scratch property, and a high flatness satisfying a high level required for high precision polishing has been strongly demanded from the industrial field, and various attempts have been made, but the actual situation has not been found yet.

Documents of the prior art

Patent document

Patent document 1 Japanese patent laid-open No. 2014-111296

Patent document 2 and japanese patent No. 5710353

Patent document 3 japanese patent No. 5738731

Patent document 4 japanese patent No. 5623927

Patent document 5, japanese patent No. 5623927, extensive application

Patent document 6, japanese patent No. 5393434, extensive application

Disclosure of Invention

Problems to be solved by the invention

The present invention addresses the problem of providing a polishing pad that has a high polishing rate and can obtain an object to be polished that has excellent flatness (less edge rounding).

Means for solving the problems

As a result of diligent research directed toward solving the above problems, the present inventors have found that a polishing pad having a high polishing rate and capable of obtaining an object to be polished having excellent high flatness (less edge rounding) can be provided by making the ratio of the soft segment composition to the hard segment within a specific range and having a tan δ peak value of a specific value or more in a specific temperature range in dynamic viscoelasticity measurement, and have completed the present invention.

That is, the polishing pad of the present invention is a cured product of a urethane resin composition containing a main agent (i) containing a urethane prepolymer (a) which is a reaction product of a polyol component (a) containing a polyol (a1) having a molecular weight of 300 or more and a short-chain diol (a2) having a molecular weight of less than 300 and a polyisocyanate (b) as at least a part of raw materials, and which has an isocyanate group at a terminal, and a curing agent (ii) which contains a polytetramethylene glycol at a content of 40 mass% or more and 90 mass% or less, wherein the content of the short-chain diol (a2) is 1 mass% or more in the polyol component (a), and wherein the cured product has a peak of tan δ in a range of 120 ℃ or more and 200 ℃ or less in a dynamic viscoelasticity measurement in which a measurement frequency is 1Hz, and a peak value of tan delta in the range of 120 ℃ to 200 ℃ is 0.18 or more.

ADVANTAGEOUS EFFECTS OF INVENTION

The polishing pad of the present invention can provide a polishing pad having a high polishing rate and capable of obtaining an object to be polished having excellent flatness (less edge rounding).

Drawings

Fig. 1 is a Scanning Electron Microscope (SEM) image of a cross section (slice plane) of the polishing pad of example 1.

Fig. 2 is a Scanning Electron Microscope (SEM) image of a cross section (slice plane) of the polishing pad of comparative example 1.

FIG. 3 is a graph showing the dynamic viscoelasticity measurement of the polishing pad of example 3.

Fig. 4 is a distribution diagram of the height measured by a spectroscopic interference laser displacement meter on the surface of the silicon wafer polished by the polishing pad of example 3.

FIG. 5 is a graph showing the dynamic viscoelasticity measurement of the polishing pad of comparative example 7.

Fig. 6 is a distribution diagram of the height measured by a spectroscopic interference laser displacement meter on the surface of the silicon wafer polished by the polishing pad of comparative example 7.

Detailed Description

The polishing pad is a cured product of a urethane resin composition containing a main agent (i) of a urethane prepolymer (A) and a curing agent (ii), wherein the cured product has a peak value of tan delta in a range of 120 ℃ to 200 ℃ in a dynamic viscoelasticity measurement with a measurement frequency of 1Hz, and the peak value of tan delta in the range of 120 ℃ to 200 ℃ is 0.18 or more. It is considered that the presence of the peak in the dynamic viscoelasticity measurement suggests that a fine domain having a specific viscoelasticity exists in the cured product, and in the present invention, a high polishing rate and a high flatness of the polished object can be achieved by the presence of the fine domain. In the present invention, the fine domains can be generated by specifying the composition of the polyol component (a).

In the dynamic viscoelasticity measurement in which the measurement frequency is 1Hz, the peak value of tan δ is preferably in the range of 120 ℃ to 180 ℃, and more preferably in the range of 110 ℃ to 170 ℃.

The peak value of tan δ is preferably 0.20 or more, more preferably 0.25 or more, and further preferably 0.3 or more, and the upper limit is not particularly limited, and may be, for example, 1 or less, and further may be 0.8 or less.

In the main agent (i), the urethane prepolymer (a) is a product obtained by reacting a polyol component (a) with a polyisocyanate (b) (a product obtained by reacting a polyol component (a) with a polyisocyanate (b) as at least a part of raw materials), and has an isocyanate group at a terminal.

The polyol component (a) may contain one or two or more kinds of polyols, and at least contains a polyol (a1) having a molecular weight of 300 or more (hereinafter, sometimes simply referred to as "polyol (a 1)") and a short-chain diol (a2) having a molecular weight of less than 300 (hereinafter, sometimes simply referred to as "short-chain diol").

The polyol (a1) can form a soft segment in the resulting polishing pad. The number average molecular weight of the polyol (a1) is preferably 700 or more, more preferably 1,100 or more, and even more preferably 1,400 or more, and preferably 8,000 or less, more preferably 5,000 or less, even more preferably 3,000 or less, and particularly preferably 2,500 or less.

In the present specification, the number average molecular weight can be measured by gel permeation chromatography (gpc) using polystyrene as a standard sample. In the case where two or more kinds of polyols are contained as the polyol (a1), the number average molecular weight of the polyol (a1) can be calculated as a weighted average value based on the number average molecular weight and the mass ratio of each polyol.

The number of hydroxyl groups contained in the polyol is preferably two or more and five or less.

The polyol (a1) comprises a polyether polyol (a 1-1). The polyether polyol (a1-1) may be a polyoxyalkylene polyol obtained by ring-opening polymerization of a cyclic ether, or may be obtained by using one or more compounds having two or more groups containing active hydrogen atoms as an initiator.

The cyclic ether preferably has 2 to 10 carbon atoms, more preferably 2 to 6 carbon atoms, and further preferably 2 to 4 carbon atoms. The hydrogen atom contained in the cyclic ether may be substituted with a halogen atom. As the cyclic ether, one or two or more kinds may be used, and for example, there may be mentioned: ethylene oxide, propylene oxide, 1, 2-butylene oxide, 2, 3-butylene oxide, styrene oxide, epichlorohydrin, tetrahydrofuran, alkylated tetrahydrofuran, and the like.

As the initiator, one or two or more kinds may be used, and for example, there may be mentioned: compounds having two active hydrogen atoms such as ethylene glycol, diethylene glycol, propylene glycol, trimethylene glycol, 1, 3-butanediol, 1, 4-butanediol, 1, 6-hexanediol, neopentyl glycol, and water; and compounds having three or more active hydrogen atoms such as glycerin, diglycerin, trimethylolethane, trimethylolpropane, hexanetriol, monoethanolamine, diethanolamine, triethanolamine, ethylenediamine, pentaerythritol, and granulated sugar.

The polyether polyol (a1-1) contains at least polytetramethylene glycol. The polytetramethylene glycol contained in the polyol component (a) has a number average molecular weight of 300 or more, preferably 1,100 or more, more preferably 1,300 or more, and preferably 4,000 or less, more preferably 3,000 or less, and further preferably 2,500 or less. When two or more polytetramethylene glycols having different number average molecular weights are contained, the number average molecular weight of the polytetramethylene glycol can be calculated as a weighted average value based on the number average molecular weight and the mass ratio of each polytetramethylene glycol.

The content of the polytetramethylene glycol in the polyol component (a) is 40% by mass or more, preferably 50% by mass or more, more preferably 60% by mass or more, and 90% by mass or less, preferably 85% by mass or less, more preferably 80% by mass or less.

The content of the polytetramethylene glycol in the polyol (a1) is preferably more than 50% by mass, more preferably 60% by mass or more, still more preferably 70% by mass or more, particularly preferably 75% by mass or more, and 100% by mass or less. It is particularly preferred that the polyol (a1) is polytetramethylene glycol.

The polyether polyol (a1-1) may also comprise a polyoxypropylene polyol. The number average molecular weight of the polyoxypropylene polyol is 300 or more, preferably 400 or more, and preferably 5,000 or less, more preferably 2,000 or less, and still more preferably 1,000 or less. When two or more polyoxypropylene polyols having different number average molecular weights are contained, the number average molecular weight of the polyoxypropylene polyol can be calculated as a weighted average value based on the number average molecular weight and the mass ratio of each polyoxypropylene polyol.

The number of hydroxyl groups contained in the polyoxypropylene polyol is 2 or more, preferably 3 or more, and preferably 5 or less, and more preferably 4 or less.

In the case where a polyoxypropylene polyol is contained, the content of the polyoxypropylene polyol (a1) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and still more preferably 30 parts by mass or less, relative to 100 parts by mass of polytetramethylene glycol.

In the polyol (a1), the content of the polyether polyol (a1-1) is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more, with the upper limit being 100% by mass.

The polyol (a1) may contain other polyols (a1-2) in addition to the polyether polyol (a 1-1). As the other polyol (a1-2), one or two or more kinds may be used, and examples thereof include: polyester polyols, polycarbonate polyols, polybutadiene polyols, polyacrylic polyols, polyisoprene polyols, and the like.

As the polyester polyol, one or two or more kinds may be used, and for example, there may be mentioned: a polyester polyol obtained by reacting a low molecular weight polyol with a polycarboxylic acid; polyester polyols obtained by ring-opening polymerization of cyclic ester compounds such as epsilon-caprolactone; and polyester polyols obtained by copolymerizing these.

As the low molecular weight polyol, one or two or more kinds can be used, and for example, polyols having a molecular weight of 50 or more and less than 300 are mentioned, and for example: aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, 1, 4-butanediol, 1, 6-hexanediol, diethylene glycol, neopentyl glycol, and 1, 3-butanediol; alicyclic polyols such as cyclohexanedimethanol; aromatic ring-containing polyols such as bisphenol A and bisphenol F. Among them, 1, 6-hexanediol and neopentyl glycol are preferable.

As the polycarboxylic acid that can be used in the production of the polyester polyol, one or two or more species may be used, and for example: aliphatic polycarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedicarboxylic acid; aromatic polycarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid; anhydrides and esters thereof.

The polycarbonate polyol is obtained by esterification of carbonic acid and a carbonate with a polyol. As the polyol, one or two or more kinds may be used, and for example, there may be mentioned: 1, 3-propanediol, 1, 4-butanediol, 1, 6-hexanediol, diethylene glycol, polyethylene glycol, polyoxypropylene glycol, polytetramethylene glycol, and the like.

Examples of the polybutadiene polyol include polyols obtained by adding an alkylene oxide (e.g., ethylene oxide, propylene oxide, etc.) to polybutadiene.

Examples of the polyacrylic polyol include polyols obtained by copolymerizing an acrylic ester with a vinyl compound or the like.

Examples of the polyisoprene polyol include polyols obtained by adding an alkylene oxide (e.g., ethylene oxide, propylene oxide, etc.) to polyisoprene.

In the polyol component (a), the content of the polyol (a1) is preferably 60% by mass or more, more preferably 70% by mass or more, and preferably less than 100% by mass, more preferably 99% by mass or less.

The short chain diol (a2) may form hard segments in the resulting polishing pad. As the short-chain diol (a2), one or two or more kinds of diols having a molecular weight of less than 300 can be used, and examples thereof include: ethylene glycol, diethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 2-methyl-1, 3-propanediol, 2-butyl-2-ethyl-1, 3-propanediol, 1, 3-butanediol, 1, 4-butanediol, neopentyl glycol (2, 2-dimethyl-1, 3-propanediol), 2-isopropyl-1, 4-butanediol, 3-methyl-2, 4-pentanediol, 1, 5-pentanediol, 3-methyl-1, 5-pentanediol, 2-methyl-2, 4-pentanediol, 2, 4-dimethyl-1, 5-pentanediol, 2, 4-diethyl-1, aliphatic diols such as 5-pentanediol, 1, 5-hexanediol, 1, 6-hexanediol, 2-ethyl-1, 3-hexanediol, 2-ethyl-1, 6-hexanediol, 1, 7-heptanediol, 3, 5-heptanediol, 1, 8-octanediol, 2-methyl-1, 8-octanediol, 1, 9-nonanediol, and 1, 10-decanediol, cyclohexanedimethanol (e.g., 1, 4-cyclohexanedimethanol), cyclohexanediol (e.g., 1, 3-cyclohexanediol, 1, 4-cyclohexanediol), and alicyclic diols such as 2-bis (4-hydroxycyclohexyl) -propane.

Among them, the short-chain diol (a2) is preferably an aliphatic diol, and particularly preferably diethylene glycol.

The content of the short-chain diol (a2) in the polyol component (a) is 1% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, and preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less.

In the polyol component (a), the content of the polyol (a1) and the short-chain diol (a2) is preferably 80% by mass or more, more preferably 90% by mass or more, and still more preferably 95% by mass or more, with the upper limit being 100% by mass.

The polyol component (a) may contain other polyol (a3) in addition to the polyol (a1) and the short-chain diol (a 2). Examples of the other polyol (a3) include: polyhydric alcohols having a molecular weight of less than 300 and having three or more hydroxyl groups, such as trimethylolethane, trimethylolpropane, hexitol, pentosanol, glycerin, polyglycerol, pentaerythritol, dipentaerythritol, and tetramethylolpropane.

As the polyisocyanate (b), one or two or more kinds can be used, and for example, there can be mentioned: polyisocyanates having an alicyclic structure such as cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate; aromatic polyisocyanates such as 4, 4 '-diphenylmethane diisocyanate, 2, 4' -diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, xylene diisocyanate, and tetramethylxylene diisocyanate. Among these, in terms of high hardness of the polishing pad and further improvement in polishing rate, aromatic polyisocyanate is preferable, and tolylene diisocyanate or diphenylmethane diisocyanate is preferable, and tolylene diisocyanate is particularly preferable.

The equivalent ratio (NCO/OH) of the isocyanate group contained in the polyisocyanate (b) to the hydroxyl group contained in the polyol component (a) is preferably 1.3 or more, more preferably 1.5 or more, and preferably 6.5 or less, more preferably 4 or less, and particularly preferably 3 or less. As the molar ratio (NCO/OH) is larger, the viscosity of the urethane prepolymer (a) can be reduced, and the flow rate can be stabilized to improve the mixing property in the production of the polishing pad, thereby facilitating the improvement of the quality. Further, the smaller the molar ratio (NCO/OH), the more the viscosity of the urethane prepolymer (A) increases, and the usable time can be extended.

The urethane prepolymer (a) is a product (a product after a urethanization reaction) obtained by reacting the polyol component (a) with the polyisocyanate (b). The reaction sequence of the polyol (a1), the short-chain diol (a2) and, if necessary, another polyol (a3) with the polyisocyanate (b) is not particularly limited, and the polyol (a1), the short-chain diol (a2) and, if necessary, the another polyol (a3) may be reacted simultaneously with the polyisocyanate (b), or after the polyol (a1) is reacted with the polyisocyanate (b), the resultant product may be reacted with the short-chain diol (a2) and, if necessary, the another polyol (a 3).

The isocyanate group equivalent of the urethane prepolymer (a) is preferably 200 g/eq.or more, more preferably 250 g/eq.or more, and preferably 800 g/eq.or less, more preferably 600 g/eq.or less.

The isocyanate group equivalent (NCO equivalent) of the urethane prepolymer (a) represents the following value: according to JIS-K-7301: 2003, a sample is dissolved in dry toluene, an excess of di-n-butylamine solution is added thereto, a reaction is carried out, and the residual di-n-butylamine is back-titrated with a hydrochloric acid standard solution to obtain a value.

The viscosity (80 ℃) of the urethane prepolymer (A) is preferably 2,000 mPas or less, more preferably 1,500 mPas or less, further preferably 1,200 mPas or less, and may be, for example, 300 mPas or more, further may be 400 mPas or more.

The viscosity (80 ℃) of the urethane prepolymer (A) can be measured at a temperature of 80 ℃ using a type B viscometer.

The main agent (i) may contain urethane prepolymer other than the urethane prepolymer (a). The content of the urethane prepolymer (a) is preferably 70% by mass or more, more preferably 80% by mass or more, and even more preferably 90% by mass or more of the total of the urethane prepolymer (a) and the other urethane prepolymers, and the upper limit is 100% by mass.

In addition, the main agent (i) may further contain a polyisocyanate. As the polyisocyanate, the polyisocyanates exemplified as the polyisocyanate (b) can be used, and aromatic polyisocyanates such as 4, 4' -diphenylmethane diisocyanate and tolylene diisocyanate are particularly preferable; and polyisocyanates having an alicyclic structure such as dicyclohexylmethane diisocyanate and isophorone diisocyanate.

The curing agent (ii) contains a compound having an active hydrogen atom-containing group ([ NH ] group and/or [ OH ] group) that reacts with the isocyanate group of the main agent (i). As the compound having a group containing an active hydrogen atom, one or two or more kinds of compounds can be used, and examples thereof include: aliphatic or alicyclic amine compounds such as ethylenediamine, propylenediamine, hexamethylenediamine, and isophoronediamine; aromatic amine compounds such as phenylenediamine, 3 '-dichloro-4, 4' -diaminodiphenylmethane, and polyamino-chlorophenylmethane compounds; compounds having two or more hydroxyl groups such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 3-methyl-1, 5-pentanediol, bisphenol a, alkylene oxide adducts of bisphenol a, polyether polyols, polyester polyols, polycaprolactone polyols, polycarbonate polyols, and the like; a polymer (preferably a dimer to a tetramer) of the aromatic amine compound; and mixtures of these, and the like.

The mixture is preferably a mixture containing a polymer of the aromatic amine compound, and the content of the polymer in the mixture is preferably 10% by mass or more, more preferably 20% by mass or more, and preferably 80% by mass or less, more preferably 70% by mass or less.

The mixture may also further comprise a polyol, preferably a polyether polyol. The polyol that can be contained in the mixture is preferably a polyether polyol (in particular, polyoxytetramethylene glycol), and the number average molecular weight of the polyol is preferably 300 or more, and preferably 3,000 or less, more preferably 2,000 or less, and further preferably 1,500 or less.

The urethane resin composition may further contain an auxiliary (iii).

The auxiliary (iii) contained in the urethane resin composition preferably contains a polyol, and the polyol may be the same as or different from the polyol (a1) forming the urethane prepolymer (a). The polyol may be one or two or more species, and examples thereof include polyoxyalkylene polyols obtained by ring-opening polymerization of the cyclic monoethers, and those obtained by using one or two or more species of the compounds having two or more active hydrogen atom-containing groups as an initiator.

The content of the polyol in the auxiliary (iii) is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more, with the upper limit being 100% by mass.

The auxiliary (iii) may further contain at least one selected from the group consisting of water, a catalyst described later, and a foam inhibitor described later.

When the auxiliary (iii) is contained in the urethane resin composition, the content of the auxiliary (iii) may be, for example, 0.1 part by mass or more, further 1 part by mass or more, preferably 10 parts by mass or less, and more preferably 5 parts by mass or less, relative to 100 parts by mass of the urethane prepolymer.

The polishing pad which can obtain an object to be polished having a high polishing rate after polishing and excellent high flatness (less edge rounding) is preferably one having a ratio of the total number of moles of groups capable of reacting with isocyanate groups contained in the above-mentioned curing agent (ii) and an optionally used auxiliary agent (iii) described later to the number of moles of isocyanate groups in the main agent (i) ([ total number of moles of groups capable of reacting with isocyanate groups in the above-mentioned curing agent (ii) and the optionally used auxiliary agent (iii) ]/[ number of moles of isocyanate groups in the urethane prepolymer (a) ]. hereinafter referred to as "R value") of 0.7 to 1.1, more preferably 0.8 to 1.

The amount of the curing agent (ii) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and preferably 50 parts by mass or less, more preferably 30 parts by mass or less, relative to 100 parts by mass of the main agent (i).

The urethane resin composition used in the present invention contains, as essential components, a main agent (i) containing the urethane prepolymer (a) and a curing agent (ii) containing a compound reactive with isocyanate, and may contain other additives. The other additive may be contained in any one of the main agent (i), the curing agent (ii), and the auxiliary agent (iii) used as needed, and may be contained in the main agent (i) or the curing agent (ii) unless it reacts with or evaporates from the main agent (i) or the curing agent (ii), but the additive that reacts or evaporates is preferably contained in the auxiliary agent (iii) used as needed.

As the other additives, one or two or more kinds may be used, and for example, there may be mentioned: water (reactive blowing agent), chemical blowing agent, physical blowing agent, catalyst, foam stabilizer, abrasive grain, filler, pigment, thickener, antioxidant, ultraviolet absorber, surfactant, flame retardant, plasticizer, and the like.

Among them, when the polishing pad is obtained by a water foaming method using the urethane resin composition, water is preferably used as a reactive foaming agent. When the foaming agent is water, the content of water is preferably 0.01 parts by mass or more and 1 part by mass or less with respect to 100 parts by mass of the main agent (i).

As the blowing agent other than water, a chemical blowing agent or a physical blowing agent may be used. As the chemical blowing agent, there are azodicarbonamide (ADCA), N '-Dinitropentamethylenetetramine (DPT), 4' -oxybis (benzenesulfonyl hydrazide, OBSH), inorganic hydrogen carbonate, a combination of hydrogen carbonate and an organic acid salt, and the like. As the physical blowing agent, chlorofluorocarbon-based HFC-245fa, HFC-365mfc, HCFO-1233zd, HFO-1336mzz and the like exist as cyclopentane or n-pentane which is a hydrocarbon-based. The amount of the foaming agent may be appropriately adjusted so as to obtain a target polishing pad density.

As the catalyst, one or two or more kinds may be used, and for example, there may be mentioned: tertiary amine catalysts such as N, N-dimethylaminoethyl ether, triethylenediamine, dimethylethanolamine, triethanolamine, N, N, N ', N' -tetramethylhexamethylenediamine, N-methylimidazole, and the like; and metal catalysts such as dioctyltin dilaurate. Among these, a tertiary amine catalyst is preferable in terms of shapeable stable foaming, and N, N-dimethylaminoethyl ether is more preferable.

In the case of using the catalyst, the content of the catalyst is preferably 0.001 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the main agent (i) in order to form stable foams.

The foam stabilizer may be a silicone foam stabilizer, and one or two or more kinds thereof may be used. Examples thereof include "Toray Silicone (Toray Silicone) SH-193", "Toray Silicone (Toray Silicone) SH-192" and "Toray Silicone (Toray Silicone) SH-190" manufactured by Toray Dow Corning (Toray Dow Coming) Co., Ltd.

When the foam stabilizer is used, the content of the foam stabilizer is preferably 0.001 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the main agent (i) in order to stably form fine bubbles.

Examples of the method for producing a polishing pad using the urethane resin composition include the following methods: the main agent (i), the curing agent (ii), and optionally the auxiliary agent (iii) are mixed and injected into a mold, foamed and cured to obtain a foamed molded article, and the foamed molded article is taken out of the mold and cut into a sheet.

In most cases, the auxiliary (iii) is used in the case of water foaming by using 3, 3 '-dichloro-4, 4' -diaminomethane (3, 3 '-dichoro-4, 4' -diaminomethane, MBOCA) for the curing agent (ii). The addition destination of water as a reactive foaming agent at the time of water foaming cannot be added to the main agent (i) because the main agent (i) reacts with water. In addition, when added to dissolved MBOCA, it is not added because it evaporates at 100 ℃ or higher. Therefore, the addition destination of water is preferably the auxiliary (iii).

When the auxiliary (iii) is contained in the urethane resin composition, the content of the auxiliary (iii) may be, for example, 0.1 part by mass or more, further 1 part by mass or more, preferably 10 parts by mass or less, and more preferably 8 parts by mass or less, relative to 100 parts by mass of the main agent (i).

When the auxiliary (iii) is used, it is preferable to prepare the auxiliary (iii) by sufficiently mixing a polyol, water, a catalyst, a foam stabilizer, or the like in advance. For example, the following methods can be cited: the main agent (i), the hardening agent (ii), and the auxiliary agent (iii) are put into different tanks of a mixing and casting machine, the main agent (i) is heated to preferably 40 to 80 ℃, the hardening agent (ii) is heated to preferably 40 to 120 ℃, the auxiliary agent (iii) is heated to 30 to 70 ℃, and the main agent (i), the hardening agent (ii), and the auxiliary agent (iii) are mixed by the mixing and casting machine.

In the case where the auxiliary agent (iii) is not used, other additives may be added to the essential main agent (i) or the curing agent (ii), and are preferably added to the curing agent (ii). A curing agent (ii) prepared by sufficiently mixing water, a catalyst, a foam stabilizer, and the like with a compound having an active hydrogen atom-containing group ([ NH ] group and/or [ OH ] group) that reacts with an isocyanate group is prepared in advance. For example, the following methods can be cited: the main agent (i) and the hardening agent (ii) are put into respective different tanks of a mixing and casting machine, the main agent (i) is warmed to preferably 40 to 80 ℃, the hardening agent (ii) is warmed to preferably 30 to 70 ℃, and the respective are mixed by the mixing and casting machine.

Examples of the method for producing a polishing pad from the urethane resin composition include the following methods: the urethane resin composition is foamed and cured in a mold (preferably, in a mold) to obtain a foamed cured product, and is further post-cured. The obtained cured foam may be further molded, if necessary. Specifically, the urethane resin composition is mixed by the mixer/caster, the respective components are discharged from the mixer/caster, the obtained mixture is injected into a mold previously heated to 40 to 120 ℃, and the mold is closed, and for example, foamed and cured at a temperature of 50 to 130 ℃ for 10 minutes to 10 hours to obtain a foamed and cured product. Then, the obtained cured foam is taken out and preferably post-cured at 100 to 120 ℃ for 8 to 20 hours. The foamed hardened material obtained in the above manner is sliced to produce the polishing pad of the present invention.

The thickness of the polishing pad may be suitably determined depending on the application, and is preferably in the range of, for example, 0.6mm to 3 mm.

In addition, as another method for producing a polishing pad using the urethane resin composition, for example, the following methods can be mentioned: the main agent (i) containing fine bubbles (hereinafter, abbreviated as "main agent (i ') containing fine bubbles") is obtained by a gas loading method, a urethane composition containing the main agent (i') containing fine bubbles and a curing agent (ii) is mixed and injected into a mold to be cured to obtain a fine bubble-containing molded article, and the molded article is taken out from the mold and cut into a sheet.

As a method for obtaining the main agent (i') containing fine bubbles from the main agent (i), for example, a method of introducing a non-reactive gas such as nitrogen, carbonic acid gas, helium, or argon into the main agent (i) and mechanically introducing bubbles is cited.

As a method for mixing the urethane composition, for example, the main fine bubble-containing agent (i ') and the curing agent (ii) are put into separate tanks of a mixing and casting machine, the main fine bubble-containing agent (i') is heated to preferably 40 to 80 ℃, the curing agent (ii) is heated to preferably 40 to 120 ℃, and the respective components are mixed by the mixing and casting machine.

Then, the respective components are discharged from the mixing and casting machine, the obtained mixture is injected into a mold previously heated to 40 to 120 ℃, and the mold is closed, foamed at a temperature of, for example, 50 to 130 ℃, and cured for 10 minutes to 10 hours, thereby obtaining a foamed molded article. After that, the obtained foam-molded product is taken out and post-cured preferably at 100 to 120 ℃ for 8 to 20 hours.

Next, the foamed molded product is sliced into a sheet shape with an appropriate thickness to obtain a polishing pad. The thickness of the polishing pad after slicing may be suitably determined depending on the application, and is, for example, in the range of 0.6mm to 3 mm.

In addition, as another method for producing a polishing pad using the urethane composition, for example, the following methods can be mentioned: when the main agent (i) and the curing agent (ii) are mixed by a mixer-caster, a non-reactive gas is introduced into a mixer portion and mixed, a mechanically foamed (mechanical front) mixture is injected into a mold and cured to obtain a foamed molded article, and the foamed molded article is taken out from the mold and cut into a sheet.

Further, as another method for producing a polishing pad using the urethane resin composition, for example, the following methods can be mentioned: the main agent (i) or the curing agent (ii) is made to contain hollow plastic spheres (microspheres) having a diameter of 20 to 120 μm, and both solutions of the main agent and the curing agent are mixed and cured to obtain a molded article containing the hollow plastic spheres, which is then sliced into a sheet.

The polishing pad of the present invention has a high polishing rate and can achieve high flatness (less edge rounding), and is useful for polishing processing of optical lenses, glass substrates for Liquid Crystal Displays (LCDs), glass substrates for hard disks (HDDs), glass disks for recording devices, optical lenses, silicon wafers, semiconductor devices, and the like, which require high polishing rate and high level of flatness (edge rounding). Particularly, it is useful for polishing a material to be polished having a vickers hardness of 1500 or less, and more particularly, it is useful for polishing a silicon wafer or glass.

Vickers hardness is one of the indexes of indentation hardness, and is determined by pressing a rigid body (indenter) made of diamond into a test object and using the area of an indentation formed at that time. As a test method, JIS-Z-2244 is available. The approximate vickers hardness of each type of material to be ground is approximately as follows.

Silicon carbide (SiC): 2300-2500 parts of sapphire: 2300. silicon: 1050. quartz glass: 950. various glasses: 500-700.

As a polishing method using the polishing pad of the present invention, for example, in the case of polishing a silicon wafer, the following methods (CMP polishing method using free abrasive grains) can be mentioned: slurry (weakly alkaline aqueous colloidal silica solution) is dropped onto a polishing pad, and a polishing object is pressed against the pad in accordance with the slurry under pressure, and the platen with the pad attached thereto is rotated (rotated) to polish the object.

Examples

The present invention will be described more specifically with reference to examples.

In the examples, the number average molecular weight of the polyol (a1) was measured by gel permeation chromatography (GPC method).

A measuring device: high-speed GPC apparatus ("HLC-8220 GPC" manufactured by Tosoh corporation): the following columns (all manufactured by Tosoh Co., Ltd.) were connected in series and used.

"TSKgel G5000" (7.8 mmI.D.. times.30 cm). times.1 roots

"TSKgel G4000" (7.8mm I.D.. times.30 cm). times.1 roots

"TSKgel G3000" (7.8 mmI.D.. times.30 cm). times.1 roots

"TSKgel G2000" (7.8 mmI.D.. times.30 cm). times.1 roots

A detector: RI (differential refractometer)

Temperature of the pipe column: 40 deg.C

And (3) dissolving and separating liquid: tetrahydrofuran (THF)

Flow rate: 1.0mL/min

Injection amount: 100 μ L (tetrahydrofuran solution with a sample concentration of 0.4% by mass)

Standard sample: the calibration curve was prepared using the following standard polystyrene.

(Standard polystyrene)

"TSKgel Standard polystyrene A-500" manufactured by Tosoh corporation "

"TSKgel Standard polystyrene A-1000" manufactured by Tosoh corporation "

TSKgel Standard polystyrene A-2500 manufactured by Tosoh corporation "

"TSKgel Standard polystyrene A-5000" manufactured by Tosoh corporation "

TSKgel Standard polystyrene F-1 manufactured by Tosoh corporation "

TSKgel Standard polystyrene F-2 manufactured by Tosoh corporation "

TSKgel Standard polystyrene F-4 manufactured by Tosoh corporation "

TSKgel Standard polystyrene F-10 manufactured by Tosoh corporation "

TSKgel Standard polystyrene F-20 manufactured by Tosoh corporation "

TSKgel Standard polystyrene F-40 manufactured by Tosoh corporation "

TSKgel Standard polystyrene F-80 manufactured by Tosoh corporation "

"TSKgel Standard polystyrene F-128" manufactured by Tosoh corporation "

TSKgel Standard polystyrene F-288 manufactured by Tosoh corporation "

"TSKgel Standard polystyrene F-550" manufactured by Tosoh corporation "

(Synthesis examples 1 to 4, comparative Synthesis examples 1 to 3, and comparative Synthesis examples 5 to 9 Synthesis of urethane prepolymer (A1) to urethane prepolymer (A4), urethane prepolymer (A '1) to urethane prepolymer (A' 3), and urethane prepolymer (A '5) to urethane prepolymer (A' 9))

A5-liter four-necked round-bottomed flask equipped with a nitrogen gas inlet, a condenser for cooling, a thermometer and a stirrer was charged with the polyisocyanate (b) shown in Table 1, and stirring was started. Then, the polyol (a1) shown in Table 1 was charged and mixed, and the reaction was carried out at 80 ℃ for 3 hours under a nitrogen atmosphere. Then, the short-chain diols (a2) shown in table 1 were reacted at 80 ℃ for 3 hours while paying attention to heat generation, thereby obtaining NCO-equivalent isocyanate group-terminated urethane prepolymers (a1) to (a4), isocyanate group-terminated urethane prepolymers (a '1) to (a' 3), and isocyanate group-terminated urethane prepolymers (a '5) to (a' 9) shown in table 1.

(Synthesis example 5)

A5-liter four-necked round-bottomed flask equipped with a nitrogen gas inlet, a condenser for cooling, a thermometer and a stirrer was charged with the polyisocyanate (b) shown in Table 1, and stirring was started. Then, the polyol (a1) shown in Table 1 was charged and mixed, and the reaction was carried out at 80 ℃ for 3 hours under a nitrogen atmosphere. Then, the short chain diol (a2) shown in Table 1 was reacted at 80 ℃ for 3 hours while paying attention to heat generation, thereby obtaining NCO equivalent: 371 of an isocyanate group-terminated urethane prepolymer. Then, in order to remove free TDI (unreacted TDI) from the obtained isocyanate group-terminated urethane prepolymer, a thin film distillation treatment was further performed, thereby obtaining an NCO equivalent: 435 isocyanate group-terminated urethane prepolymer (a 5).

(comparative Synthesis example 4)

In the same manner as in Synthesis example 5, NCO equivalent was obtained: 380 isocyanate group-terminated urethane prepolymer. Then, in order to remove free TDI (unreacted TDI) from the obtained isocyanate group-terminated urethane prepolymer, a thin film distillation treatment was further performed, thereby obtaining an NCO equivalent: 438 of an isocyanate group-terminated urethane prepolymer (A' 4).

[ Table 1]

The corresponding urethane prepolymer (A5) was subjected to thin film distillation

In tables 1 to 2, the following examples are given,

polytetramethylene glycol 1 (also referred to as "PTMG 1000") means polytetramethylene glycol (number average molecular weight 1,000),

polytetramethylene glycol 2 (also referred to as "PTMG 2000") means polytetramethylene glycol (number average molecular weight 2,000),

polytetramethylene glycol 3 (also referred to as "PTMG 650") means polytetramethylene glycol (number average molecular weight 650),

polyoxypropylene polyol 1 ("EL 430" manufactured by Asahi glass urethane) represents a polyoxypropylene polyol (hydroxyl number: 3, number average molecular weight: 430),

polyoxypropylene polyol 2 ("EL 410 NE" manufactured by Asahi glass urethane) represents a polyoxypropylene polyol (hydroxyl number: 4, number average molecular weight: 410),

polyoxypropylene polyol 3 ("EL 3030" manufactured by Asahi glass urethane) represents a polyoxypropylene polyol (hydroxyl number: 3, number average molecular weight: 3,000),

polyoxypropylene polyol 4 ("EL 1030" manufactured by Asahi glass urethane) represents a polyoxypropylene polyol (hydroxyl number: 3, number average molecular weight: l,000),

polyoxybutylene glycol 1 (also referred to as "PBG 2000") means polyoxybutylene glycol (number average molecular weight 2,000),

polybutylene adipate 1 (also referred to as "BGAA 2000") denotes a polyester polyol (hydroxyl number 2, number average molecular weight 2,000) comprising 1, 4-butanediol and adipic acid,

polybutylene adipate 2 (also referred to as "BGAA 1000") denotes a polyester polyol (hydroxyl number 2, number average molecular weight 1,000) comprising 1, 4-butanediol and adipic acid,

polyisocyanate (T80) represents TDI (isomer ratio of 2, 4/2, 6 of 80/20),

polyisocyanate (T100) represents 2, 4-TDI.

(examples 1 to 5 and comparative examples 1 to 9)

The isocyanate group-terminated urethane prepolymer (a1) to (a5) and the isocyanate group-terminated urethane prepolymer (a '1) to (a' 9) obtained in synthesis examples 1 to 5 and comparative synthesis examples 1 to 9 were adjusted to a temperature of 80 ℃. Next, the curing agent (MBOCA) was melted at 120 ℃ and temperature-adjusted to obtain a curing agent (ii). Further, the temperature of the prepared liquid shown in Table 3 was adjusted at 35 ℃ to obtain an auxiliary agent (iii).

Next, the main component (i) shown in Table 4 was charged into the reaction vessel, the temperature was adjusted to 80 ℃, then 35 ℃ C liquid was charged in the amount shown in tables 3 to 4, 120 ℃ curing agent (ii) was immediately charged in the amount shown in Table 4, and the mixture was immediately stirred for 20 seconds by a high-speed mixer. 6000 parts of the mixed solution of the main agent (i)/the curing agent (ii)/the auxiliary agent (iii) was poured into a mold of 500mm × 500mm × 40mm adjusted to 60 ℃, the mold was closed, and the mixture was held at 60 ℃ for 1 hour, after which a foamed molded article in the form of a pig was taken out. The obtained foamed molded article in the form of a pellet was post-cured at 100 ℃ for 16 hours.

The obtained foam molded article in the form of an ingot was cut into pieces having a thickness of 1.5mm by a slicer to obtain sheet-like polishing pads (P1) to (P5) and polishing pads (P '1) to (P' 8). The density and hardness of the obtained polishing pad, and the evaluation results of tan δ peak temperature, tan δ value, polishing rate, and edge rounding at 120 to 200 ℃ in the dynamic viscoelasticity measurement with the measurement frequency of 1Hz are shown in table 5.

(examples 6 to 8 and comparative examples 10 to 11)

The isocyanate group-terminated urethane prepolymer shown in Table 4 was prepared as the main agent (i) by adjusting the temperature to 80 ℃. The temperature of the prepared liquids (B1 and B2) shown in table 3 was adjusted at 40 ℃ to obtain a curing agent (ii). Next, the main component (i) was charged into the reaction vessel in the amount of parts shown in Table 4, the temperature was adjusted to 80 ℃, then the prepared solutions (B1, B2) at 40 ℃ in the amount of parts shown in Table 4 were charged, and immediately stirred for 20 seconds by a high-speed mixer. 6000 parts of the mixed solution of the main agent (i)/the curing agent (ii) was poured into a 500mm × 500mm × 40mm mold adjusted to 60 ℃, the mold was closed, and the mixture was held at 60 ℃ for 1 hour, and then the molded foam in the form of an ingot was taken out. The obtained foamed molded article in the form of a pellet was post-cured at 80 ℃ for 16 hours.

The obtained foam molded article in the form of an ingot was cut into pieces having a thickness of 1.5mm by a slicer to obtain sheet-like polishing pads (P6) to (P8), and polishing pads (P '9) to (P' 10). The density and hardness of the obtained polishing pad, and the evaluation results of tan δ peak temperature, tan δ value, polishing rate, and edge rounding at 120 to 200 ℃ in the dynamic viscoelasticity measurement with the measurement frequency of 1Hz are shown in table 5.

the measurement methods (evaluation methods) of tan δ peak temperature, tan δ value, polishing rate, and edge rounding are as follows.

[ method for measuring tan delta peak temperature and tan delta value ]

The viscoelasticity of a polishing pad having a thickness of 1.5mm was evaluated by measuring tan δ peak temperature (also referred to as "loss coefficient peak temperature") (. degree. C.) by dynamic viscoelasticity analysis using a polishing pad having a thickness of 1.5mm in the following order in accordance with JIS K7244.

The storage modulus of elasticity (E ') and the loss modulus of elasticity (E') of the polishing pad were measured in a tensile mode using a viscoelastometer (model: DMS6100, manufactured by SII Nano Technology, Inc.) under conditions of a temperature range of-100 ℃ to 200 ℃, a temperature rise rate of 5 ℃/min, and a frequency of 1 Hz.

When E "/E 'is tan δ, the temperature at which tan δ becomes the maximum value in the range of 120 ℃ to 200 ℃ is referred to as" tan δ peak temperature (° c) ", and E"/E' at the tan δ peak temperature is referred to as the tan δ value.

The measurement conditions were as follows:

(sample size) 5 mm. times.60 mm. times.1.5 mm

(span) 20mm

(dependent variable) 0.05%

[ method for evaluating polishing Rate ]

The polishing pads obtained in examples and comparative examples were attached to one surface of a double-sided tape, and a platen of a polishing machine was attached to the other surface of the double-sided tape, and the polishing rate was measured by the following apparatus, conditions, and calculation formula.

Grinding machine: FAM 18 GPAW (draft Fam) company, 457m water-cooled platen diameter)

Grinding conditions are as follows:

(pad pretreatment) dressing treatment (flattening and sharpening of the pad) was performed by a diamond dresser (#100) until lines drawn on the pad surface in a line of 2cm in length and breadth with a red pencil disappeared. The water supply amount is 200ml/min

Thickness of 4-inch single crystal silicon wafer (object to be polished): 540 μm

(silicon wafer supporting method) ceramic block/micro porous pad (water adsorption) silicon wafer (grinder cooling water) 20 deg.C

(slurry) colloidal silica solution Neodah (Nitta Haas) manufactured by N6501, Inc. diluted 20 times

(slurry flow) 100ml/min (circulation type)

(platen speed) 50rpm (traction rotation type)

(grinding pressure) 30kPa

(grinding time) 20 minutes

The polishing rate was calculated from the difference in weight between the polyurethane polishing pads before and after polishing.

That is, the polishing rate (μm/min) × 10000/(density of single crystal silicon (g/cm) (weight of silicon wafer before polishing) (g))/(weight of silicon wafer after polishing (g))/((g/cm))³) X area of silicon wafer (cm)²) X grinding time (min)

The density of the single crystal silicon was 2.329g/cm³

Area of the silicon wafer was 20.4cm²

[ method of evaluating edge blending ]

After the polishing rate evaluation, a re-dressing treatment was performed for 1 hour using a diamond dresser (# 100). Thereafter, the polishing was performed under the following polishing conditions instead of using a new object to be polished. After polishing, the height of the polished object was measured by a spectroscopic interference laser displacement meter.

Grinding conditions are as follows:

(silicon wafer supporting method) ceramic block/wax/silicon wafer

(mill cooling water) 20 deg.C

(slurry flow) 100ml/min (circulation type)

(platen speed) 50rpm (traction rotation type)

(grinding pressure) 30kPa

(grinding time) 60 minutes

Laser displacement meter conditions:

(MACHINE) SI-F10/KS-1100 (manufactured by Keyence, Inc.)

(measurement point) 101 × 101 ═ 10201 points (measurement was performed until the ceramic block was attached)

(analysis software) KS Analyzer (Keyence, Inc.)

(site for evaluating edge rounding) line segment (diameter) passing through the center of silicon wafer

(edge rounding evaluation) was evaluated by the maximum height-the height of the 2mm portion from the left end.

[ Table 3]

In the context of Table 3, the following examples are,

aromatic aminochlorophenylmethane mixture means a mixture comprising 3, 3' -dichloro-4, 4-diaminophenylmethane (MBOCA) and its polymers and a polyether polyol (active hydrogen equivalent: 189),

togyocat (TOYOCAT) ET, manufactured by Tosoh Co., Ltd., represents a mixture of bis (dimethylaminoethyl) ether (70%) and dipropylene glycol (30%),

SH-193 is manufactured by Toray Dow Coming, Inc., and represents a silicone foam stabilizer.

[ Table 4]

In Table 4, MBOCA represents 3, 3' -dichloro-4, 4-diaminophenylmethane.

[ Table 5]

The polishing pads of examples 1 to 8 are those of the present invention, and have a high polishing rate, and can obtain an object to be polished having excellent flatness (less edge rounding).

The tan δ values of comparative examples 1 to 3, 5 and 7 were small, the tan δ peak temperatures of comparative examples 4, 7, 9 and 10 were low, the content of polytetramethylene glycol contained in the polyol component (a) of comparative example 6 was low, and the tan δ peak temperatures of comparative example 8 were not present, so that both high polishing rate and high flatness could not be achieved.

Further, as shown in fig. 1, the cross section of the polishing pad of the present invention showed fluffing, and it was confirmed that fine domains having specific viscoelasticity existed. On the other hand, the polishing pad of the comparative example had a smooth cross-section as shown in FIG. 2. FIG. 3 is a graph showing the dynamic viscoelasticity measurement of the polishing pad of example 3. Fig. 4 is a distribution diagram of the height measured by a spectroscopic interference laser displacement meter on the surface of the silicon wafer polished by the polishing pad of example 3. FIG. 5 is a graph showing the dynamic viscoelasticity measurement of the polishing pad of comparative example 7. Fig. 6 is a distribution diagram of the height measured by a spectroscopic interference laser displacement meter on the surface of the silicon wafer polished by the polishing pad of comparative example 7.

Claims

1. A polishing pad which is a cured product of a urethane resin composition containing a main agent (i) containing a urethane prepolymer (A) and a curing agent (ii), characterized in that:

the urethane prepolymer (A) is a reaction product of a polyol component (a) comprising a polyol (a1) having a molecular weight of 300 or more and a short-chain diol (a2) having a molecular weight of less than 300, and a polyisocyanate (b), and has an isocyanate group at the terminal,

the polyol component (a) contains a polytetramethylene glycol at a content of 40 to 85 mass%,

the content of the short-chain diol (a2) is not less than 1% by mass in the polyol component (a),

the cured product has a peak value of tan delta in a range of 120 ℃ to 200 ℃ in a dynamic viscoelasticity measurement with a measurement frequency of 1Hz, and

the peak value of tan delta in the range of 120 ℃ to 200 ℃ is 0.18 or more.

2. The polishing pad of claim 1, wherein

The short-chain diol (a2) with the molecular weight less than 300 is diethylene glycol.

3. The polishing pad according to claim 1 or 2, wherein

The polyol (a1) is polytetramethylene glycol, and the content of polytetramethylene glycol in the polyol component (a) is 60 mass% or more.

4. The polishing pad according to claim 1 or 2, wherein

The number average molecular weight of the polyol (a1) is 1,100 or more.

5. The polishing pad according to claim 1 or 2, wherein

The polyisocyanate (b) is an aromatic polyisocyanate.

6. The polishing pad according to claim 1 or 2, wherein

The hardener (ii) is an aromatic amine compound.