JP2013086217A - Urethane resin composition for polishing pad, polyurethane polishing pad, and method of manufacturing polyurethane polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a CMP polishing pad, which has superior polishing characteristics, or a superior high polishing rate, non-scratchability, and flatness.SOLUTION: An urethane resin composition for polishing pad, which includes a base resin containing an isocyanate group terminal urethane prepolymer (A) and a curing agent containing an isocyanate group reactive compound (B).The urethane resin composition for polishing pad contains fumed silica (C).

Description

  The present invention relates to a urethane resin composition for a thermosetting urethane (TSU) type polishing pad used in the glass polishing field such as a glass substrate, a silicon wafer, and a semiconductor device, a polyurethane polishing pad obtained using the same, and polyurethane polishing. The present invention relates to a method for manufacturing a pad.

A liquid crystal display (LCD) glass substrate, a hard disk (HDD) glass substrate, a recording device glass disk, an optical lens, a silicon wafer, a semiconductor device, and the like are required to have high surface flatness and in-plane uniformity.
In semiconductor devices, as the degree of integration of semiconductor circuits increases rapidly, miniaturization and multilayer wiring for the purpose of higher density have progressed, and a technique for further flattening the processed surface has become important. On the other hand, with a glass substrate for a liquid crystal display, higher flatness of a processed surface is required with an increase in the size of the liquid crystal display. As the demand for flatness increases, the required performance such as polishing accuracy and polishing efficiency in polishing is increasing.

A chemical mechanical polishing method, so-called CMP (Chemical Mechanical Polishing), is widely used as a polishing method capable of forming a surface having excellent flatness in the manufacturing process of semiconductor devices and optical devices.
In the CMP method, a so-called free abrasive method is generally employed in which polishing is performed by supplying a slurry (polishing liquid) in which abrasive grains (polishing particles) are dispersed in an alkali solution or an acid solution during polishing. That is, the object to be polished (the processed surface thereof) is flattened by a mechanical action by the abrasive grains in the slurry and a chemical action by the alkali solution or the acid solution. With the sophistication of flatness required for processed surfaces, the demands for polishing performance such as polishing accuracy and polishing efficiency required for CMP methods, specifically, high polishing rate, non-scratch property, and high flatness are increasing. Yes. As a polishing pad of the CMP free abrasive grain method, for example, a technique for optimizing the degree of wear and stabilizing the polishing performance has been reported (for example, see Patent Document 1). On the other hand, a fixed abrasive type polishing pad has also been proposed without using free abrasive grains due to waste liquid treatment and cost problems (see, for example, Patent Document 2).

  However, since the loose abrasive type polishing pad has a low R value of 0.7 to 0.9 in order to control the amount of wear, the urethane resin is somewhat brittle and the aging period is several months. There is a problem that quality is not stable. Moreover, the fixed abrasive type polishing pad which is the above-mentioned non-free abrasive type has a problem that scratches are apt to occur.

  As described above, although there is a strong demand from industry for a polishing pad that satisfies the high polishing rate, non-scratch property, and flatness that are constantly required for precision polishing, it has not yet been found.

JP 2010-76075 A JP 2011-142249 A

  The problem to be solved by the present invention is to provide a polishing pad of CMP method having excellent polishing characteristics, that is, high polishing rate, non-scratch property and flatness.

The inventors of the present invention made extensive studies on the composition of the urethane resin while researching to solve the above problems. However, although various compositions were examined, the above problem could not be solved.
Therefore, the present inventors have appropriate wear characteristics even when the R value is as close to 1.0 as possible to reduce the quality fluctuation, and further, the open cell type (low closed cell rate type) to increase the slurry holding power. The addition of silica was studied with the goal of a polishing pad of).
As a result, it has been found that a polishing pad to which fumed silica is added can provide a polishing pad that satisfies the above-mentioned problems, and has completed the present invention.

  That is, the present invention is a urethane resin composition for a polishing pad comprising a main agent containing an isocyanate group-terminated urethane prepolymer (A) and a curing agent containing an isocyanate group-reactive compound (B), further comprising a fume. The present invention provides a urethane resin composition for a polishing pad, a polyurethane polishing pad, and a method for producing a polyurethane polishing pad, characterized by containing dosilica (C).

  The urethane resin composition for a polishing pad of the present invention can provide a polishing pad excellent in high polishing rate, non-scratch property, and flatness. Further, even when used over time, the polishing characteristics are not easily lowered, and the durability is excellent.

Therefore, the polishing pad obtained by using the urethane resin composition for a polishing pad of the present invention includes a glass substrate for a liquid crystal display (LCD), a glass substrate for a hard disk (HDD), a glass disk for a recording device, an optical lens, and a silicon wafer. , Semiconductor devices, sapphire substrates for LEDs, silicon carbide substrates, semiconductor substrates such as gallium arsenide substrates, optical substrates, magnetic substrates, etc., high-precision polishing that requires high surface flatness and in-plane uniformity Useful for.

  The polishing pad urethane resin composition of the present invention comprises a main agent containing an isocyanate group-terminated urethane prepolymer (A), a curing agent containing an isocyanate group-reactive compound (B), fumed silica (C), It contains.

  Next, the isocyanate group-terminated urethane prepolymer (A) used in the present invention will be described.

  The isocyanate group-terminated urethane prepolymer (A) (hereinafter abbreviated as prepolymer (A)) is obtained by reacting polyisocyanate (a1) and polyol (a2) according to a conventionally known method. The reaction method for obtaining the prepolymer (A) is not particularly limited.

  When manufacturing the said prepolymer (A), a tertiary amine catalyst, an organometallic catalyst, etc. can be accelerated | stimulated as needed.

  The isocyanate group equivalent (NCO equivalent) of the prepolymer (A) is preferably in the range of 200 to 750, more preferably in the range of 250 to 700. In addition, although the unit of the equivalent of the said prepolymer (A) uses g / eq, it abbreviates.

  Although it does not specifically limit as said polyisocyanate (a1), For example, Tolylene diisocyanate (TDI-100; 2, 4- body toluene diisocyanate, TDI-80; 2, 4- body and 2,6- body toluene 2,4-isomer / 2,6-isomer = 80/20 mass ratio), tolidine diisocyanate (TODI), diphenylmethane diisocyanate (abbreviated as MDI; its 4,4′-isomer, 2, 4′-isomer, or 2,2′-isomer, or a mixture thereof), polymethylene polyphenyl polyisocyanate, carbodiimidized diphenylmethane polyisocyanate, xylylene diisocyanate (XDI), 1,5-naphthalene diisocyanate (NDI), tetra Aromatic diisocyanates such as methyl xylene diisocyanate Or alicyclic diisocyanates such as isophorone diisocyanate (IPDI), hydrogenated diphenylmethane diisocyanate (hydrogenated MDI), hydrogenated xylylene diisocyanate (hydrogenated XDI), or hexamethylene diisocyanate, dimer diisocyanate, norbornene diisocyanate, etc. Aliphatic diisocyanates, etc., among them, tolylene diisocyanate (TDI), tolidine diisocyanate (TODI), hydrogenated diphenylmethane diisocyanate (hydrogenated MDI) can improve the polishing characteristics, and the reactivity during work This is preferable because it is easier to control. These may be used alone or in combination of two or more.

  The polyol (a2) is not particularly limited. For example, at least one selected from the group consisting of a low molecular weight polyol, a polyester polyol, a polycarbonate polyol, a polyether polyol, a polyester polyol, a polybutadiene polyol, and a silicone polyol is used. However, polyols other than these may be used. The kind and amount of these polyols are appropriately selected depending on the intended use. From the viewpoint of hydrolysis resistance, polyether polyols are preferred, and polytetramethylene ether glycol is particularly preferred.

  Examples of the low molecular weight polyol include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, and 2-butyl-2-ethyl-1,3-propane. Diol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol (2,2-dimethyl-1,3-propanediol), 2-isopropyl-1,4-butanediol, 3-methyl-2 , 4-pentanediol, 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-1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, -Ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, 2-methyl-1,8- Aliphatic diols such as octanediol, 1,9-nonanediol, 1,10-decanediol, cyclohexanedimethanol (for example, 1,4-cyclohexanedimethanol), cyclohexanediol (for example, 1,3-cyclohexanediol, 1,4 -Cyclohexanediol), alicyclic diols such as 2-bis (4-hydroxycyclohexyl) -propane, trimethylolethane, trimethylolpropane, hexitols, pentitols, glycerin, polyglycerin, pentaerythritol, dipentaerythritol, Tetramethylol Trivalent or more polyols, such as propane and the like.

  Examples of the polyester polyol include esters of polyols such as the low molecular weight polyols, and polycarboxylic acids, ester-forming derivatives of polyvalent carboxylic acids (esters, anhydrides, halides, etc.), lactones, hydroxycarboxylic acids, and the like. A compound. Examples of the polyvalent carboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, 2-methylsuccinic acid, and 2-methyladipine. Acid, 3-methyladipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,8-dimethyldecanedioic acid, 3,7-dimethyldecanedioic acid, aliphatic dicarboxylic acid (for example, hydrogenated dimer acid) Dimer acid etc.), aromatic dicarboxylic acid (eg phthalic acid, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid etc.), alicyclic dicarboxylic acid (eg cyclohexane dicarboxylic acid etc.), tricarboxylic acid (eg trimellitic acid, trimesic acid, Castor oil fatty acid trimer, etc.), tetracarboxylic acid (eg, pyromellitic acid), and the like. Examples of the ester-forming derivative of the polyvalent carboxylic acid include acid anhydrides, halides (chloride, bromide, etc.), esters (for example, methyl ester, ethyl ester, propyl ester, isopropyl ester, butyl ester, isobutyl ester, amyl). And lower aliphatic esters such as esters). Examples of the lactone include γ-caprolactone, δ-caprolactone, ε-caprolactone, dimethyl-ε-caprolactone, δ-valerolactone, γ-valerolactone, and γ-butyrolactone. The hydroxycarboxylic acid may be, for example, a hydroxycarboxylic acid having a structure in which the lactone is ring-opened.

  Examples of the polyether polyol include an ethylene oxide adduct, a propylene oxide adduct, polytetramethylene glycol, and an oxide adduct of the low molecular polyol. Examples of the ethylene oxide adduct include diethylene glycol and triethylene glycol. Examples of the propylene oxide adduct include dipropylene glycol and tripropylene glycol. Examples of the oxide adduct of the low-molecular polyol include an ethylene oxide adduct, a propylene oxide adduct, ethylene oxide, and a propylene oxide adduct.

  As said polycarbonate polyol, what is obtained by making carbonate and / or phosgene react with the polyol mentioned later can be used, for example.

  As the carbonate ester, for example, methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate and the like can be used.

  Examples of the polyol that can react with the carbonate ester or phosgene include, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, and tripropylene glycol. 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 2 -Methyl-1,3-propanediol, neo Nthyl glycol, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octane Dihydroxy compounds of relatively low molecular weight such as diol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, hydroquinone, resorcin, bisphenol A, bisphenol F, 4,4′-biphenol, polyethylene glycol, polypropylene glycol Polyether polyols such as polytetramethylene glycol, and polyester polyols such as polyhexamethylene adipate, polyhexamethylene succinate, and polycaprolactone can be used.

The number average molecular weight of the polyol (a2) excluding the low molecular weight polyol is more preferably 500 to 5,000, and particularly preferably 500 to 2,000, from the viewpoint of excellent strength elongation and viscoelasticity of the urethane resin. Further preferred. In addition, the number average molecular weight of the said polyol (a2) shows the number average molecular weight calculated | required from a hydroxyl value and an acid value.
Number average molecular weight = (56100 × f) / (hydroxyl value + acid value)
F: number of functional groups

  Next, the hardening | curing agent mix | blended and mixed in combination with the main ingredient containing the said prepolymer (A) is demonstrated.

  The curing agent includes an isocyanate group-reactive compound (B) which is an essential component (hereinafter abbreviated as a reactive compound (B)), water (D) which is a foaming agent, a catalyst, a silicone foam stabilizer, and the like. You may contain.

Although the said reactive compound (B) will not be specifically limited if it has favorable reactivity with respect to the compound which has an isocyanate group, For example, a diamine compound and polyols are mentioned.
Representative examples of the diamine compound include ethylenediamine, 1,6-hexamethylenediamine, piperazine, 2,5-dimethylpiperazine, isophoronediamine, 4,4′-dicyclohexylmethanediamine, 3,3′-dimethyl-4,4. '-Dicyclohexylmethanediamine, 1,4-cyclohexanediamine, 1,2-propanediamine, diethylenetriamine, triethylenetetramine, 3,3'-dichloro-4,4'-diaminodiphenylmethane, polyaminochlorophenylmethane compound, Pandex E- And amine compounds such as 50 (trademark: manufactured by DIC Corporation, polyaminocurlphenylmethane compound), and hydrazines such as hydrazine and acid hydrazide.
Examples of the polyols include polyether polyols such as polytetramethylene glycol and polypropylene glycol, polyester polyols, polycarbonate polyols, and low molecular weight polyols. These may be used alone or in combination of two or more. That is, an amine compound dissolved in a polyol may be used. Moreover, when using 2 or more types together in the above-mentioned thing, it is good also as a 2 liquid type urethane resin composition of the said main ingredient and the hardening | curing agent containing 2 or more types of reactive compounds (B). The curing agent may be divided into two or more liquids (for example, a reactive compound (B) and a reactive compound (B) ′ different from the above (B)).

  As the reactive compound (B), among the above-mentioned compounds, a polyaminochlorophenylmethane compound is preferable from the viewpoint of hot water resistance and wear resistance, and 3,3′-dichloro-4,4′-diaminodiphenylmethane is particularly preferable.

  As a compounding quantity of the said reactive compound (B), Preferably it is the range of 15-80 mass parts with respect to 100 mass parts of said prepolymers (A), More preferably, it is the range of 20-60 mass parts. .

  The water (D) is blended in order to serve as a foaming agent in the water foaming method. As a compounding quantity of water, Preferably it is the range of 0.05-3 mass parts with respect to 100 mass parts of said reactive compounds (B), More preferably, it is the range of 0.5-2 mass parts. .

  The method for adding the water (D) when mixing the main agent and the curing agent is not particularly limited. For example, as the curing agent in advance, the reactive compound (B) and water (D) and, if necessary, a catalyst or Additives such as silicone foam stabilizers are added and mixed, then the first component (A) and the second component (B + D + additive) are mixed and foamed and cured, for example, reactive compounds (B ) Has a melting point of 100 ° C. or higher, mix with another reactive compound (B ′) having a melting point of 100 ° C. or lower with water (D) and, if necessary, an additive such as a catalyst or a silicone foam stabilizer. Next, a method of mixing, foaming and curing the first component (A), the second component (B), and the third component (B ′ + D + additive) can be mentioned.

  The type and addition amount of the catalyst may be selected in consideration of the time from mixing the catalyst to pouring into the mold, temperature, final foaming state, etc., and there is no particular limitation.

  Examples of the catalyst include, but are not limited to, triethylenediamine, N, N, N ′, N′-tetramethylhexanediamine, N, N, N ′, N′-tetramethylpropanediamine, N, N, N ', N ″, N ″ -pentamethyldiethylenetriamine, N, N ′, N′-trimethylaminoethylpiperazine, N, N-dimethylcyclohexylamine, N, N, N ′, N′-tetramethylethylenediamine, bis (3-dimethylaminopropyl) -N, N-dimethylpropanediamine, N, N-dicyclohexylmethylamine, bis (dimethylaminoethyl) ether, N, N ′, N ″ -tris (3-dimethylaminopropyl) hexahydro -S-triazine, N, N-dimethylbenzylamine, N, N-dimethylaminoethoxyethoxy Ethanol, N, N-dimethylaminohexanol, N, N-dimethylaminoethoxyethanol, N, N, N′-trimethylaminoethylethanolamine, N, N, N′-trimethyl-2-hydroxyethylpropylenediamine, 1- Amine-based catalysts such as methylimidazole, 1-isobutyl-2-methylimidazole, 1,2-dimethylimidazole, dimethylethanolamine, triethanolamine, dibutyltin dilaurate, dioctyltin dilaurate, tin octylate 2-ethylhexanoic acid, Examples thereof include metal catalysts such as potassium octylate, dibutyltin lauryl mercaptide, and bismuth tris (2-ethylhexanoate). Among these, tertiary amines having strong foaming properties are preferable. Problems with property, physical properties, etc. In Kere, any catalyst can be used. These may be used alone or in combination of two or more.

  The compounding amount of the catalyst is preferably in the range of 0.01 to 1.0 part by mass, more preferably 0.05 to 0.3 part by mass with respect to 100 parts by mass of the reactive compound (B). Part range. If the amount of the catalyst is within such a range, a polishing pad having a stable foamed state can be obtained.

  Next, fumed silica (C) used in the present invention will be described.

  Although the said fumed silica (C) may be mix | blended with either the said main ingredient or the said hardening | curing agent, since many compounding quantities are put, it mix | blends with the 1st component of the said prepolymer (A) with a large compounding ratio. More preferably.

  The fumed silica (C) may be either non-modified fumed silica (atomaceous silica) or a particle surface of fumed silica that has been hydrophobically modified with various surface treatment agents.

  The fumed silica is obtained by a dry method, and specifically is silicon dioxide obtained by vaporizing silicon tetrachloride and hydrolyzing it in a high-temperature flame. However, in the manufacturing process, an aggregate of these is formed.

  Siloxane groups and silanol groups are present on the surface of the agglomerated silicon dioxide and show hydrophilicity. On the other hand, hydrophobicity is imparted by reacting this silanol group with a surface treatment agent.

  Examples of the surface treatment agent include dimethyldichlorosilane, dimethylsilicone oil, hexamethyldisilazane, octylsilane, hexadecylsilane, aminosilane, methacrylsilane, octamethylcyclotetrasiloxane, and polydimethylsiloxane.

Moreover, as a specific surface area by the BET method of the said fumed silica (C), it is preferable that it is 30-300 m < ² > / g, and it is more preferable that it is 60-200 m < ² > / S.

Commercially available hydrophilic types of fumed silica (C) include Aerosil 50, Aerosil 90G, Aerosil 130, Aerosil 200, Aerosil 200CF, Aerosil 200V, Aerosil 300, Aerosil 300CF (above, manufactured by Nippon Aerosil Co., Ltd.) Etc. are available.
As hydrophobic types, Aerosil DT4, Aerosil NA200Y, Aerosil NA50H, Aerosil NA50Y, Aerosil NAX50, Aerosil R104, Aerosil R106, Aerosil R202, Aerosil R202W90, Aerosil R504, Aerosil R711, Aerosil R700, Aerosil R780, Aerosil R780 Aerosil R805VV90, Aerosil R812, Aerosil 812S, Aerosil R816, Aerosil R8200, Aerosil R972, Aerosil R972V, Aerosil R974, Aerosil RA200HS, Aerosil RX200, Aerosil RX300, Aerosil RX200R, Aerosil RY200R 50 (or more, manufactured by Nippon Aerosil Co., Ltd.) and the like are available. Other than Nippon Aerosil Co., Ltd., similar fumed silica can be obtained from Tokuyama Co., Ltd.

  The amount of the fumed silica (C) used is 0.5 to 2.0% by mass with respect to 100 parts by mass of the isocyanate group-terminated urethane prepolymer (A), from the viewpoint of liquid viscosity and polishing characteristics. Is more preferable.

  Next, the urethane resin composition for a polishing pad of the present invention will be described.

  Compounding ratio of the main agent and the curing agent for obtaining the urethane resin composition for polishing pad of the present invention, that is, R value [R] = [in the curing agent including the reactive compound (B) and water (D) The total number of moles of groups capable of reacting with the isocyanate groups] / [total number of moles of isocyanate groups in the prepolymer (A) as the main agent] is preferably in the range of 0.7 to 1.1, more preferably The mixing ratio may be determined so as to be in the range of 0.8 to 1.0.

  The urethane resin composition for a polishing pad of the present invention includes, for example, a foam stabilizer, an antioxidant, a defoamer, an ultraviolet absorber, abrasive grains, a filler, a pigment, a thickener, a surfactant, a flame retardant, Known and commonly used additives such as plasticizers, lubricants, antistatic agents, heat stabilizers, blending resins and the like can be used at any stage of the production process as long as the object of the present invention is not impaired. The additive described in the present invention is an example, and the kind thereof is not particularly limited.

  The foam stabilizer is not particularly limited as long as it can stably form fine bubbles. For example, SZ-1919, SH-192, SH- 190, SZ-580, SRX-280A, SZ-1959, SZ-1328E, SF-2937F, SF-2938F, SZ-1671, SH-193, SZ-1923 (manufactured by Toray Dow Corning Co., Ltd.) It is done.

  Examples of the filler include carbonate, silicic acid, silicate, hydroxide, sulfate, borate, titanate, metal oxide, carbon, and organic matter.

  Next, the polyurethane polishing pad of the present invention and the manufacturing method thereof will be described below.

  The polyurethane polishing pad of the present invention is obtained by using the urethane resin composition for polishing pad. For example, the above-described additives are added to the urethane resin composition for polishing pad, if necessary. The mixture is mixed, poured into a mold having a predetermined shape, foamed and cured, and the foamed molded product is taken out of the mold and processed into a suitable shape such as a sheet.

  As a method for producing the polyurethane polishing pad of the present invention, in addition to the water foaming method described above, for example, a method of adding hollow beads, a mechanical froth method, a mechanical foaming method of introducing and mixing a non-reactive gas into a mixing chamber, A publicly known and commonly used method such as a chemical foaming method can be employed and is not particularly limited.

  As a manufacturing method of the polyurethane polishing pad of the present invention, for example, a series of manufacturing methods including [Step 1] to [Step 5] can be exemplified.

  It should be noted that any method may be selected in any step as long as the additive can be added without any problem and uniform blending and mixing can be performed without any problem.

[Step 1] A step of adjusting the main agent (first component).
For example, polyisocyanate (a1) and polyol (a2) are charged in a reactor equipped with a nitrogen introduction tube, a cooling condenser, a thermometer, and a cooler, respectively, and preferably 70 to 90 ° C. while stirring in a nitrogen atmosphere. And, more preferably, in the range of 75 to 85 ° C., the prepolymer (A) is synthesized, and the main agent containing the prepolymer (A) and preferably the hydrophobic silica (C) is obtained.

[Step 2] Mixing step of main agent and curing agent.
Next, a main agent (first component) containing the prepolymer (A) and an isocyanate group-reactive compound (B), preferably a curing agent (second component) containing water (C) and a catalyst (D). Mix and stir to make the reaction solution. However, when the melting point of the isocyanate group-reactive component is 100 ° C. or higher, for example, a third component in which water (C) and catalyst (D) are dissolved in another reactive compound (B) ′ is used as the first component. / The second component / third component may be mixed and stirred to form a reaction solution. At that time, a non-reactive gas may be introduced into the mixing chamber to form a gas dispersion reaction liquid.
When mixing, a main casting agent (first component) containing the prepolymer (A), a curing agent (second component) containing the reactive compound (B), and in some cases, the third component is mixed and casted. The main agent (first component) containing the prepolymer (A) is preferably heated to 40 to 80 ° C, and the curing agent (second component) is preferably 40 to 120 ° C. In some cases, the third component is heated to 30 to 70 ° C., and each is mixed with a mixing caster.

[Step 3] Casting step.
The reaction liquid discharged from the mixed casting machine (in some cases, a non-reactive gas dispersion reaction liquid) is preferably injected into a mold preheated to 40 to 120 ° C. using a hose or the like.

[Step 4] Curing step.
While being poured into the mold, the reaction solution is heated and held in an appropriate temperature range (for example, a range of 40 to 120 ° C.), foamed and cured, and preferably gold of 40 to 120 ° C. for 30 minutes to 2 hours. After being left in the mold, the molded product is taken out, and after-curing is preferably performed at 100 to 120 ° C. for 8 to 17 hours to obtain a molded product.

[Step 5] Slicing step.
The molded product is sliced into a sheet having an appropriate thickness. The sheet thickness after slicing may be set according to the purpose of polishing and is not particularly limited, but is preferably in the range of 0.6 to 2.0 mm, for example.

  The polyurethane polishing pad obtained as described above is fixed to a surface plate with, for example, a double-sided tape, the fixed polyurethane polishing pad is rotated together with the surface plate, and a polishing slurry containing abrasive grains is formed thereon. While constantly supplying, polishing is performed by pressing a semiconductor substrate, an optical substrate, a magnetic substrate or the like against a polyurethane polishing pad.

    As the abrasive, colloidal silica, cerium oxide, zirconium oxide, silicon carbide, alumina and the like can be used.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the scope of the present invention is not limited only to these examples.
In the present invention, “parts” is “parts by weight” and “%” is “% by weight” unless otherwise specified.
The measurement method and evaluation method used in the present invention are as follows.

[Example 1] << Manufacture of polyurethane polishing pad (P-1) >>
37 parts of tolylene diisocyanate (TDI-100) was charged into a four-necked round bottom flask equipped with a nitrogen inlet tube, a condenser for cooling, a thermometer, and a stirrer, and stirring was started. Next, 63 parts of polytetramethylene glycol (number average molecular weight 1000) was charged and mixed, and reacted at 60 ° C. for 8 hours under a nitrogen stream to obtain an isocyanate group-terminated urethane prepolymer (A-1) having an isocyanate group equivalent of 335. . 1.25 parts of hydrophilic silica (trade name: “Leoro Seal QS20L”, specific surface area = 220 m ² / g, manufactured by Tokuyama Corporation) is added to the obtained prepolymer (A-1), and a disper disperser is sufficient. The first component was mixed. The isocyanate group equivalent of the obtained first component was 342.
Subsequently, 3,3′-dichloro-4,4′-diaminophenylmethane (MBOCA) was melted at 120 ° C. to obtain a second component.
Next, 100 parts of polypropylene glycol (PPG, number average molecular weight 3000 f = 3), 7.0 parts of ion-exchanged water, 0.5 part of bis (dimethylaminoethyl) ether and a surface tension of 21.3 mN / m (25 ° C. 4 parts of a polyether-modified silicone foam stabilizer, and the mixture was sufficiently stirred and mixed to obtain the third component.
Next, the first component, the second component, and the third component were respectively charged in three tanks of a mixing type elastomer casting machine (EA-408 type, manufactured by Toho Machine Industry Co., Ltd.) and degassed under reduced pressure. Next, the first component / second component / third component = 74.1 / 22.0 so that the R value = 0.9 is obtained in a mold (inner dimensions: 500 × 500 × 20 mm) adjusted to 60 ° C. 3350 g (first + second + third component) was injected at a blending ratio of /3.9 (mass ratio).
・ Discharge rate = 7500 g / min (first + second + third component)
・ Mixer rotation speed = 3500rpm
Introducing dry air in the mixing chamber = None Thereafter, the lid of the mold was immediately closed and held at 60 ° C for 30 minutes, and then the molded product was taken out. Further, the obtained molded article was after-cured at 110 ° C. for 16 hours.
The obtained molded product was cut out to a thickness of 1.4 mm with a slicer to obtain a sheet-like polyurethane polishing pad (P-1). Table 1 shows the properties of the polishing pad obtained at the center of the molded product thickness.

[Example 2] << Manufacture of polyurethane polishing pad (P-2) >>
A polyurethane polishing pad (P-2) was obtained in the same manner as in Example 1 except that the mechanical foaming method in which the amount of dry air introduced into the mixing chamber was introduced and mixed at a rate of 10 liters / min was used.

[Example 3] << Production of polyurethane polishing pad (P-3) >>
The fumed silica (trade name: “Aerosil RY200S”, specific surface area = 130 m ² / g, manufactured by Nippon Aerosil Co., Ltd.) obtained by hydrophobically modifying hydrophilic silica (trade name: “Leosil QS20L”) with dimethyl silicone oil. A polyurethane polishing pad (P-3) was obtained in the same manner as Example 1 except for the above. The properties of the resulting polishing pad are shown in Table 1.

[Example 4] << Manufacture of polyurethane polishing pad (P-4) >>
A polyurethane polishing pad (P-4) was obtained in the same manner as in Example 3 except that the mechanical foaming method in which the amount of dry air introduced into the mixing chamber was introduced and mixed at a rate of 10 liters / min.

[Comparative Example 1] << Manufacture of polyurethane polishing pad (P'-1) >>
The first component is an isocyanate group-terminated urethane prepolymer (A-1) without introducing fumed silica, and the mixing ratio is first component / second component / third component = 73.7 / 22.3 / 3. A polyurethane polishing pad (P′-1) was obtained in the same manner as in Example 1 except that the ratio was 9 (mass ratio). Table 2 shows the properties of the obtained polishing pad.

[Comparative Example 2] << Manufacture of polyurethane polishing pad (P'-2) >>
A polyurethane polishing pad (P′-2) was obtained in the same manner as in Comparative Example 1 except that the mechanical foaming method in which the amount of dry air introduced into the mixing chamber was introduced and mixed at a rate of 10 liters / min was used.

[Method of measuring isocyanate group equivalent (NCO equivalent) of prepolymer (A)]
The NCO equivalent of the prepolymer (A) is measured according to JIS K 7301 by dissolving the sample in dry toluene, adding an excess of di-n-butylamine solution and reacting it, and removing the remaining di-n-butylamine. Determined by back titration with hydrochloric acid standard solution.

[Measurement method of number average molecular weight]
The number average molecular weight of the polyol used in the examples and comparative examples was determined as follows.
Number average molecular weight = (56100 × f) / (hydroxyl value + acid value)
F: number of functional groups
In addition, the measuring method of a hydroxyl value and an acid value was measured according to JISK1557.

[Measurement method of polishing pad thickness]
It measured with the dial gauge (significant figure: 0.01 mm) (n = 8), and made the average value thickness of the polishing pad.

[Measurement method of polishing pad density]
Length (significant figures: 0.1 mm) with a measure (n = 2), thickness (significant figures: 0.01 mm) with a dial gauge (n = 8), weight (significant figures: 0.01 g) Was measured with a balance (n = 2) and calculated according to the following formula.
Density (g / cm ³ ) = average weight / (average length 1 × average length 2 × average thickness)

[Method of measuring hardness of polishing pad]
Measurement was performed according to JIS A 7312.

[Measurement method of cell average diameter of polishing pad]
The cell diameter was measured with an image analyzer.
Apparatus: Pore Scan (manufactured by Goldluce)
Condition: Position 12
Exposure: 1000 Gain: 30
Threshold: Auto
5 measurements (batch processing)
300μm ² or less is not counted

[Existence of huge cells]
The polyurethane polishing pads obtained in Examples and Comparative Examples were visually observed to confirm the presence or absence of giant cells.
In addition, when there is even one cell having a diameter of 1 mm or more on the polyurethane polishing pad, “Yes”,
When there was not, it was described as “none”.

[Method for measuring the closed cell ratio of polishing pads]
Two sheets of 38 × 250 mm were cut from the polishing pad, and the two sheets were rolled into a “pneumatic apparent volume measuring device” (air comparison type hydrometer 1000 model manufactured by Tokyo Science Co., Ltd.) and measured. Measured according to ASTM D-2856.

[Evaluation method of polishing rate]
The polyurethane polishing pad obtained in Examples and Comparative Examples was attached to one side of the double-sided tape, the surface plate of the polishing machine was attached to the other side of the double-sided tape, and the polishing rate was measured with the following apparatus, conditions and calculation formula.
Polishing machine: FAM 18 GPA (Speed Fam, platen diameter = 457.2 mm)
Polishing conditions:
(Pad pretreatment) Dressing (pad flattening) was performed with a diamond dresser until the lines drawn vertically and horizontally at intervals of 2 cm with a red pencil disappeared on the pad surface. Water supply amount 200 ml / min (for polishing) Single crystal silicon wafer 4 inches (102 mm t = 0.45 mm)
(Slurry) Colloidal silica solution PH = 11 (Silica concentration = 2%)
(Slurry flow rate) 60 ml / min (Rotating plate speed) 50 rpm (Turning type)
(Polishing pressure) 30kPa
(Polishing time) 20 minutes (Polishing rate) Calculated from the weight difference of the polyurethane polishing pad before and after polishing. That is,
Polishing rate (μm / min) = (weight of silicon wafer before polishing (g) −weight of silicon wafer after polishing (g)) × 10000 / (density of single crystal silicon (g / cm ³ ) × silicon wafer Area (cm ² ) × polishing time (min))
* Density of single crystal silicon = 2.329 (g / cm ³ )
* Silicon wafer area = 20.4cm ²

[Scratch evaluation method]
Whether or not the silicon wafer after polishing by the above-mentioned [Evaluation method of polishing rate] has scratches was visually observed and evaluated as follows.
No scratches: “○”
There are scratches: “×”

[Evaluation method of flatness]
The flatness was evaluated by measuring the single crystal silicon wafer after polishing by the above-mentioned [Evaluation method of polishing rate] using a surface roughness meter.
Device: Foam Talysurf i120 (Tayler Hobson)
Condition: Scanning speed: 0.5 mm / min
Measurement site: Evaluate 99mm out of 102mm in diameter direction Evaluation criteria: The length of the line segment whose height difference is within ± 1.0μm is 90mm or more
Rated as “○”
If the length of the line segment where the height difference is within ± 1.0 μm is less than 90 mm,
Rated "x"

Claims (7)

A urethane resin composition for a polishing pad comprising a main agent containing an isocyanate group-terminated urethane prepolymer (A) and a curing agent containing an isocyanate group-reactive compound (B),
Furthermore, the urethane resin composition for polishing pads characterized by containing fumed silica (C). The urethane resin for polishing pads according to claim 1, wherein the fumed silica (C) is used in an amount of 0.5 to 2% by mass based on 100 parts by mass of the isocyanate group-terminated urethane prepolymer (A). Composition. The urethane resin composition for polishing pads according to claim 1, wherein the curing agent contains an isocyanate group-reactive compound (B) and water (D) as a foaming agent. The urethane resin composition for polishing pads according to claim 1, wherein the isocyanate group-reactive compound (B) is a polyaminochlorophenylmethane compound and / or a polyol. The urethane resin composition for polishing pads according to claim 4, wherein the polyaminochlorophenylmethane compound is 3,3'-dichloro-4,4'-diaminodiphenylmethane. The polyurethane polishing pad obtained using the urethane resin composition for polishing pads of any one of Claims 1-5. The urethane resin composition for a polishing pad according to any one of claims 1 to 5 is injected into a mold and foamed and cured, and the foamed molded product is taken out of the mold and sliced into sheets. A method for producing a polyurethane polishing pad.