TW201815858A - Polishing pad, method for producing polishing pad and polishing method - Google Patents

Abstract

The present invention provides a polishing pad which is a cured foam of a urethane resin composition containing (i) a base material that contains a urethane prepolymer (A) having an isocyanate group, said urethane prepolymer (A) being a reaction product of a polyol (a1) containing a polysiloxane compound represented by general formula (1) and a polyisocyanate (a2) and (ii) a curing agent, and which is characterized in that the ratio of the polysiloxane compound in the starting material for the urethane prepolymer (A) is 1% by mass or less. This polishing pad has excellent polishing rate and enables the achievement of a polished article which has less scratches in the surface of a polished material after polishing, thereby having excellent smoothness.

Description

   Polishing pad, manufacturing method of polishing pad, and polishing method   

The present invention relates to a polishing pad, a method for manufacturing a polishing pad, and a polishing method which are particularly suitable for polishing a glass substrate, a silicon wafer, a semiconductor element, and the like.

Glass substrates for liquid crystal displays (LCDs), glass substrates for hard disks (HDDs), glass disks for recording devices, lenses for optics, silicon wafers, and semiconductor devices require a high degree of surface flatness and in-plane uniformity.

In particular, with the rapid increase in the degree of integration of semiconductor circuits, the aforementioned semiconductor devices have been developed for miniaturization or multilayer wiring for the purpose of high density, and the processed surface requires a higher level of surface flatness. Further, in the aforementioned glass substrate for a liquid crystal display, as the liquid crystal display becomes larger, the processed surface also needs to have a higher surface flatness. As described above, the requirements for the flatness of the surface of the machined surface are increased, and the required performance such as the polishing accuracy and polishing efficiency of the polishing process is further increased.

Therefore, in a manufacturing process of a semiconductor element or an optical element, as a polishing method capable of forming a surface having excellent flatness, a chemical mechanical polishing method, a so-called CMP (Chemical Mechanical Polishing) method is widely used.

The CMP method generally employs a free abrasive grain method in which a slurry (polishing liquid) in which abrasive grains (abrasive particles) are dispersed in an alkaline solution or an acid solution is supplied for polishing during polishing processing. That is, the object to be polished is flattened by the mechanical action caused by the abrasive particles in the slurry, and the chemical action caused by the alkali solution or the acid solution. Here, as the flatness required for the working surface becomes higher, the polishing performance such as the polishing accuracy and polishing efficiency required by the CMP method, specifically, the requirements for high polishing rate, non-scratchability, and high flatness are increasing. As a polishing pad using a free abrasive grain method using the CMP method, for example, a technique has been reported that optimizes the degree of wear and stabilizes the polishing performance (for example, refer to Patent Document 1). In addition, for the purpose of waste liquid treatment or cost, a fixed abrasive type polishing pad that does not use a free abrasive method has also been proposed (for example, refer to Patent Document 2).

As a polishing pad using the above-mentioned free abrasive particle method, in response to a request for further heights in recent years, it has been proposed, for example, to try to achieve high polishing rate, high flatness, and low scratches (for example, by optimizing vinyl resin) (Refer to Patent Document 3), try to control the abrasion and reduce the occurrence of scratches (for example, refer to Patent Document 4), try to modify the urethane resin by epoxy modification to improve flatness or polishing speed (for example, refer to Patent Document 5), flattening using a special raw material as a raw material of the urethane resin (for example, refer to Patent Document 6) and the like.

As described above, there is a strong need in the industry for polishing pads with high polishing rates, low scratches, and high flatness to meet the needs of high-precision polishing. Although various attempts have been made, the facts have not been found.

Prior art literature Patent literature

Patent Document 1 Japanese Patent Application Publication No. 2010-76075

Patent Document 2 Japanese Patent Application Laid-Open No. 2011-142249

Patent Document 3 Japanese Patent Application Publication No. 2014-192217

Patent Document 4 Japanese Patent Application Publication No. 2014-111296

Patent Document 5 Japanese Patent Application Publication No. 2013-252584

Patent Document 6 Japanese Patent Laid-Open No. 2015-51498

The problem to be solved by the present invention is to provide a polishing pad which has an excellent polishing rate, and can obtain an abrasive with less scratches on the surface of the material to be polished after polishing and excellent smoothness.

As a result of careful research by the inventors of the present invention in order to solve the above-mentioned problems, it was found that by using a polishing pad, the above-mentioned problems can be solved and the present invention has been completed, which is an amine group containing a main agent (i) and a hardener (ii) A foamed hardened product of a formate resin composition, the main component (i) containing an isocyanate group-containing urethane as a reaction product of a polysiloxane (a1) and a polyisocyanate (a2) The ester prepolymer (A) contains the polysiloxane compound in a specific amount in the urethane prepolymer (A).

That is, the present invention relates to a polishing pad which is a polishing pad containing a foamed hardened product of a urethane resin composition of a main agent (i) and a hardener (ii), and the main agent (i) An isocyanate group-containing urethane prepolymer (A) containing a polysiloxane compound represented by the following general formula (1) as a reactant of a polyol (a1) and a polyisocyanate (a2), It is characterized in that the proportion of the polysiloxane compound in the urethane prepolymer (A) raw material is 1% by mass or less.

(In formula (1), R ¹ and R ^{3 are} each independently and represent an alkyl group having 1 to 5 carbon atoms, R ² represents an alkylene group having 1 to 5 carbon atoms, and n represents a repeating unit of 1 to 200 average value.)

The present invention also relates to a method for manufacturing a polishing pad, which is characterized by mixing and containing a urethane prepolymer having an isocyanate group obtained by reacting a polyol (a1) and a polyisocyanate (a2) ( A) The main agent (i), the hardener (ii), and the urethane resin composition of the foaming agent (iii) containing water (B) are injected into a mold, and foamed and hardened. A foamed molded product is obtained, and then the foamed molded product is taken out from a mold and sliced into a sheet shape, in which the polyol (a1) contains a polysiloxane compound represented by the aforementioned general formula (1).

Furthermore, the present invention relates to a method for polishing a material to be polished having a Vickers hardness of 1500 or less, which is characterized by using the aforementioned polishing pad.

The polishing pad of the present invention has an excellent polishing rate, and among abrasives to be polished using the polishing pad of the present invention, it is possible to obtain an abrasive having less scratches and excellent smoothness of the surface of the abrasive.

Therefore, the polishing pad of the present invention is applied to 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, a silicon wafer, a semiconductor element, and a housing of a smartphone. Optical substrates such as glass; magnetic substrates; silicon wafer substrates; element substrates and other high-precision polishing processes that require a high degree of surface flatness and in-plane uniformity are useful, especially for Vickers hardness of silicon wafers and the like Grinding of abrasives below 1500 is particularly useful.

FIG. 1 is an AFM observation diagram of a material to be polished (silicon wafer) polished using the polishing pad (P1) obtained in Example 1. FIG.

FIG. 2 is an AFM observation diagram of a material to be polished (silicon wafer) polished using the polishing pad (P'1) obtained in Comparative Example 1. FIG.

Fig. 3 is an AFM observation diagram of a material to be polished (silicon wafer) polished using the polishing pad (P'2) obtained in Comparative Example 2.

Implementation of the invention

The polishing pad of the present invention is a foamed cured product of a urethane resin composition containing a main agent (i) and a hardener (ii), and the main agent (i) contains The urethane prepolymer (A) having an isocyanate group as a reactant of the polyhydric alcohol (a1) and the polyisocyanate (a2) shown in the illustrated polysiloxane compound.

As the main agent (i), an isocyanate group-containing urethane having a polysiloxane compound represented by the following general formula (1) as a reactant of a polyol (a1) and a polyisocyanate (a2) is used. Ester prepolymer (A).

As the polyol (a1), a polysiloxane compound represented by the following general formula (1) must be used, and other polyols may be used as necessary.

As the polysiloxane compound, one represented by the following general formula (1) is used.

(In formula (1), R ¹ and R ^{3 are} each independently and represent an alkyl group having 1 to 5 carbon atoms, R ² represents an alkylene group having 1 to 5 carbon atoms, and n represents a repeating unit of 1 to 200 average value.)

The poly-silicon siloxane compound, less scratch the surface of the material to be polished after polishing to give a highly smooth and polished was obtained and the polishing pad having an excellent view of the polishing rate, R ¹ and R ³ are individually preferred Is methyl or ethyl, R ^{2 is} preferably propyl or butyl, n is preferably in the range of 10 to 100, and more preferably in the range of 15 to 50.

As the aforementioned polysiloxane compound, for example, "X-22-176B", "X-22-176DX", "Silaplane FMDA11", etc. manufactured by Shin-Etsu Chemical Industry Co., Ltd. can be obtained from commercially available products.

In addition, from the viewpoint of obtaining an abrasive with less scratches on the surface of the material to be polished after polishing and excellent smoothness, and obtaining a polishing pad having excellent polishing rate, mechanical strength, and the life of the polishing pad, the aforementioned urethane The proportion of the polysiloxane compound in the polymer (A) raw material is 1% by mass or less, preferably 0.5% by mass or less, and more preferably 0.3% by mass or less. The polysiloxane compound must be a raw material of the urethane prepolymer (A). The lower limit is preferably 0.01% by mass or more, and more preferably 0.05% by mass or more.

Here, when the ratio of the said polysiloxane compound is more than 1 mass%, a polishing rate will fall. In addition, when synthesizing the urethane prepolymer (A), due to the problem of compatibility, the mechanical strength of the polishing pad obtained due to the decrease in the reaction rate of the polysiloxane compound, or the Poor contamination of the object to be abraded by the reacted silicone compound is not preferred.

Examples of the other polyol include polyether polyol, polyester polyol, polycarbonate polyol, polybutadiene polyol, polyacrylic polyol, dimer diol, and polybutadiene. Polyols, polyisoprene polyols, and the like. Among these, from the viewpoint of further improving the polishing rate, a polyether polyol is preferred, and polybutylene glycol is particularly preferred. These other polyols may be used singly or in combination of two or more kinds.

Examples of the polyether polyol include polybutylene glycol obtained by ring-opening polymerization of tetrahydrofuran. Further, examples thereof include one or two or more compounds having two or more active hydrogen atoms as an initiator, and an alkylene oxide is additionally polymerized. Examples of the compound having two or more active hydrogen atoms include propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, Neopentyl glycol, glycerol, diglycerol, trimethylolethane, trimethylolpropane, water, hexanetriol, and the like. Examples of the alkylene oxide include propylene oxide, butylene oxide, phenylene oxide, epichlorohydrin, and tetrahydrofuran. These polyether polyols may be used alone or in combination of two or more.

As the other polyol, when the polyether polyol is used, from the viewpoint of compatibility between the polysiloxane compound and the polyether polyol, it is preferably 20 to 99.9% by mass in the polyol (a1). It is used in a range of 50 to 99.9% by mass.

Examples of the polyester polyol include polyester polyols obtained by reacting a low molecular weight polyol and a polycarboxylic acid; and those obtained by subjecting a cyclic ester compound such as ε-caprolactone to a ring-opening polymerization reaction. Polyester polyol; polyester polyol obtained by copolymerizing these; and the like. These polyester polyols may be used alone or in combination of two or more.

Examples of the low molecular weight polyol include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, and 1,3-butanediol. Aliphatic polyols having a molecular weight of about 50 to 300, such as diols; polyols having an aliphatic cyclic structure, such as cyclohexanedimethanol; polyols having an aromatic structure, such as bisphenol A and bisphenol F. Among these, 1,6-hexanediol and neopentyl glycol are preferred.

Examples of the polycarboxylic acid that can be used in the production of the polyester polyol include aliphatic polycarboxylic acids such as succinic acid, adipic acid, sebacic acid, and dodecanedioic acid; terephthalic acid, Aromatic polycarboxylic acids such as isophthalic acid, phthalic acid, and naphthalenedicarboxylic acids; such anhydrides or esters.

The polycarbonate polyol is obtained by performing an esterification reaction of carbonic acid and carbonate with a polyol. Examples of the polyol include 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, polyethylene glycol, polypropylene glycol, and polytetramethylene ether. Diols, etc. These polycarbonate polyols may be used alone or in combination of two or more.

The number average molecular weight of the other polyol is preferably in the range of 200 to 5,000, and more preferably in the range of 300 to 3,000 from the standpoint of polishing rate. It should be noted that the number average molecular weight of the other polyol is a value measured by a colloidal permeation chromatography (GPC) method under the following conditions.

Measuring device: High-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation)

Column: The following columns made by Tosoh Co., Ltd. were used in series.

`` TSKgel G5000 '' (7.8mmI.D. × 30cm) × 1

`` TSKgel G4000 '' (7.8mmI.D. × 30cm) × 1

`` TSKgel G3000 '' (7.8mmI.D. × 30cm) × 1

`` TSKgel G2000 '' (7.8mmI.D. × 30cm) × 1

Detector: RI (differential refractometer)

Column temperature: 40 ℃

Eluent: Tetrahydrofuran (THF)

Flow rate: 1.0mL / min

Injection volume: 100 μL (tetrahydrofuran solution with a sample concentration of 0.4% by mass)

Standard sample: Use the following standard polystyrene to make a calibration curve.

    (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" by Tosoh Corporation

Examples of the polyisocyanate (a2) include polyisocyanates having an alicyclic structure such as cyclohexane diisocyanate, dicyclohexylmethane diisocyanate, and isophorone diisocyanate; 4,4'-diphenyl Aromatics such as methane diisocyanate, 2,4'-diphenylmethane diisocyanate, carbodiimide modified diphenylmethane diisocyanate, crude diphenylmethane diisocyanate, benzenediisocyanate, toluene diisocyanate, naphthalene diisocyanate, etc. Polyisocyanate; aliphatic polyisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate. Among these, from the viewpoint of further improving the high hardness and polishing rate of the polishing pad, an aromatic polyisocyanate is preferred, and toluene diisocyanate or diphenylmethane diisocyanate is preferred. These polyisocyanates (a2) may be used alone or in combination of two or more.

The urethane prepolymer (A) is obtained by subjecting the polyol (a1) and the polyisocyanate (a2) to a urethanization reaction by a known method, and is one having an isocyanate group.

When the urethane prepolymer (A) is obtained, the molar ratio (NCO / OH) of the hydroxyl group of the polyol (a1) to the isocyanate group of the polyisocyanate (a2) is determined from the amino group. The viscosity of the ester prepolymer (A) is appropriate (for example, when it is manufactured by a mold machine, it is 500 to 2000 mPa · s at 40 to 90 ° C.), from the viewpoint of obtaining a polishing pad with few scratches and excellent polishing rate, The range of 1.3 to 6.5 is preferable, and the range of 1.5 to 4 is more preferable.

Here, if the molar ratio (NCO / OH) is less than 1.3, the viscosity of the urethane prepolymer (A) will be extremely increased, and the flow rate will become unstable and the mixing property during the manufacture of the polishing pad. Deterioration, resulting in quality degradation. On the other hand, if the molar ratio (NCO / OH) is greater than 6.5, unreacted polyisocyanate increases, and the viscosity becomes extremely low. Similarly, the flow rate becomes unstable, and the usable time becomes extremely short. Therefore, Manufacturing of polishing pads becomes difficult.

As the isocyanate group equivalent of the urethane prepolymer (A), an abrasive having less scratches on the surface of the material to be polished after polishing and excellent smoothness is obtained, and the polishing rate, mechanical strength, and polishing pad are obtained. From the viewpoint of a polishing pad having a good life, the range of 200 to 800 g / eq. Is preferable, and the range of 250 to 600 g / eq. Is more preferable. The isocyanate equivalent of the urethane prepolymer (A) means that the sample was dissolved in dry toluene according to the method specified in JIS-K-7301: 2003, and an excess of di-n-butylamine solution was added. The reaction was performed, and the residual di-n-butylamine was a value obtained by back titration with a hydrochloric acid standard solution.

The hardener (ii) is preferably one containing an active hydrogen atom ([NH] group and / or [OH] group) containing an active hydrogen atom that reacts with an isocyanate group included in the urethane prepolymer (A). Examples of the compound include aliphatic or alicyclic amine compounds such as ethylenediamine, propylenediamine, hexamethylenediamine, and isophoronediamine; phenylenediamine, 3,3'-dichloro-4 , 4'-diaminodiphenylmethane, polyaminochlorophenylmethane compounds and other aromatic amine compounds; ethylene glycol, diethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, 3 -Methyl-1,5-pentanediol, bisphenol A, alkylene oxide adduct of bisphenol A, polyether polyol, polyester polyol, polycaprolactone polyol, polycarbonate polyol, etc. Compounds having two or more hydroxyl groups and the like. These compounds may be used alone or in combination of two or more.

As the molar ratio of the group containing the active hydrogen atom contained in the hardener (ii) and the isocyanate group contained in the urethane prepolymer (A), scratches on the surface of the material to be polished after grinding are small. From the viewpoint of obtaining a polishing pad with excellent smoothness and a polishing pad with excellent polishing rate, mechanical strength, and life of the polishing pad, [R value] = ([with the aforementioned hardener (ii) and the aforementioned foaming agent] (iii) The total number of moles of the isocyanate-reactive group in (iii)] / [the number of moles of the isocyanate group of the urethane prepolymer (A)]) = 0.7 to 1.1, more preferably 0.8 to 1 range.

In addition, the hardening agent (i) is to obtain an abrasive article with less scratches on the surface of the material to be polished after polishing and excellent smoothness, and to obtain a polishing pad having excellent polishing rate, mechanical strength, and the life of the polishing pad. It is preferable to use it in the range of 10-50 mass parts with respect to 100 mass parts of said urethane prepolymer (A).

The urethane resin composition used in the present invention contains the main agent (i) and the hardener (ii) containing the above-mentioned urethane prepolymer (A) as essential components, but may optionally contain Other additives.

Examples of the other additives include a foaming agent (iii) containing water (B), a catalyst (C), a foam stabilizer (D), abrasive grains, fillers, pigments, tackifiers, and Oxidants, UV absorbers, surfactants, flame retardants, plasticizers, etc. These additives may be used alone or in combination of two or more. Among these, when using the said urethane resin composition and obtaining the polishing pad by the water foaming method, it is preferable to use the said foaming agent (iii) containing water (B).

The water (B) is a foaming agent that functions as a water foaming method, and examples thereof include ion-exchanged water and distilled water. As the usage-amount when using the said water (B), it is preferable that it is the range of 0.01-1 mass part with respect to 100 mass parts of said urethane prepolymers (A).

Furthermore, the foaming agent (iii) may contain two or more of the above-mentioned groups having an active hydrogen atom used as the curing agent (ii), either alone or in combination, for the purpose of further improving water foamability. Compound. The amount used when the compound having a group containing an active hydrogen atom is used is preferably 0.1 relative to 100 parts by mass of the urethane prepolymer (A) from the viewpoint of further improving water foamability. Range of ~ 10 parts by mass.

Moreover, it is preferable to contain a catalyst (C) as another said additive from a viewpoint which can form a stable foam.

Examples of the catalyst (C) include N, N-dimethylaminoether, triethylene glycol, dimethylethanolamine, triethanolamine, N, N, N ', N'-tetramethyl Tertiary amine catalysts such as hexamethylenediamine, N-methylimidazole; metal catalysts such as dioctyltin dilaurate, etc. These catalysts can be used alone or in combination of two or more. Among these, N, N-dimethylamino ether is preferable from the viewpoint of forming stable foam. The catalyst (C) may be included in any of the main agent (i), hardener (ii), and foaming agent (iii).

The amount used when the catalyst (C) is used is from 0.001 to 5 parts by mass based on 100 parts by mass of the urethane prepolymer (A) from the viewpoint of forming stable foam. range.

Examples of the foam stabilizer (D) include "Toray Silicon SH-193", "Toray Silicon SH-192", "Toray Silicon SH-190", etc. manufactured by Dow Corning Toray Co., Ltd. These foam stabilizers (D) may be used alone or in combination of two or more. The foam stabilizer (D) may be included in any of the main agent (i), hardener (ii), and foaming agent (iii).

The amount used when the foam stabilizer (D) is used is preferably 0.001 to 5 masses based on 100 mass parts of the urethane prepolymer (A) from the viewpoint that fine bubbles can be stably formed. Serving range.

As a method of manufacturing a polishing pad using the said urethane resin composition, the mixing | blending of the amino base containing the said main agent (i), the said hardening agent (ii), and the said foaming agent (iii) is mentioned, for example. An ester resin composition is poured into a mold, foamed and hardened to obtain a foamed molded article, and then the foamed molded article is taken out of the mold and sliced into a sheet shape to produce the method.

As a method of mixing the said urethane resin composition, the said main agent (i), the said hardening | curing agent (ii), and the said foaming agent (iii) are put into a mixing casting machine, for example. In each separate tank, the main agent (i) is preferably heated to 40 to 80 ° C, the hardener (ii) is preferably heated to 40 to 120 ° C, and the foregoing foaming agent ( iii) A method of heating the mixture to 30 to 70 ° C and mixing them individually with a mixing molder.

As a method for manufacturing a polishing pad using the aforementioned urethane resin composition, specifically, after mixing the aforementioned urethane resin composition with the aforementioned hybrid casting machine, each of them is ejected from the hybrid casting machine. Ingredients, the obtained mixture is poured into a mold previously heated to 40 to 120 ° C, the lid of the mold is closed, and foaming and hardening are performed at a temperature of, for example, 50 to 130 ° C for 10 minutes to 10 hours to obtain a foamed molded product. After that, the obtained foamed molded article is taken out, and preferably post-cured at 100 to 120 ° C. for 8 to 20 hours.

Next, the foamed molded article was sliced into a sheet shape with an appropriate thickness to obtain a polishing pad. The thickness of the polishing pad after slicing can be appropriately determined according to the application, and is, for example, in the range of 0.6 to 3 mm.

In addition, as another method for producing a polishing pad using the urethane resin composition, for example, the main agent (i) containing fine bubbles can be obtained by using the main agent (i) by a gas-loading method ( Hereinafter referred to as "the microbubble-containing main agent (i ')"), the urethane composition containing the microbubble-containing main agent (i') and the hardener (ii) is mixed and injected into a mold Then, the molded product containing the fine bubbles is hardened, and then the molded product is taken out from the mold and sliced into a sheet shape.

Examples of the method for obtaining the fine bubble-containing main agent (i ') from the main agent (i) include, for example, introducing non-reactions such as nitrogen, carbonic acid gas, helium, and argon into the main agent (i). A method of introducing gas and mechanically introducing bubbles.

Examples of a method for mixing the urethane composition include, for example, placing the fine-bubble-containing main agent (i ') and the hardener (ii) in respective separate molds of a mixing molder. It is preferred that the main agent (i ') containing fine bubbles is heated to 40 to 80 ° C, the hardener (ii) is preferably heated to 40 to 120 ° C, and each of the Don't mix.

Next, each component is discharged from the mixing mold machine, and the obtained mixture is poured into a mold previously heated to 40 to 120 ° C, and the lid of the foregoing mold is closed, and foamed and hardened at a temperature of, for example, 50 to 130 ° C. 10 Minutes to 10 hours to obtain a foamed molded article. After that, the obtained foamed molded article is taken out, and preferably post-cured at 100 to 120 ° C. for 8 to 20 hours.

Next, the foamed molded article was sliced into a sheet shape with an appropriate thickness to obtain a polishing pad. The thickness of the polishing pad after slicing can be appropriately determined according to the application, and is, for example, in the range of 0.6 to 3 mm.

In addition, as another method for producing a polishing pad using the urethane composition, for example, the main agent (i) is foamed by a mechanical foaming method to obtain a foaming main agent (i "). The urethane composition containing the foaming main agent (i ") and the curing agent (ii) is mixed, poured into a mold, and cured to obtain a foamed molded product. Next, the foamed molded product is mixed. The method is to take out the mold and slice into slices.

In addition, as another method for manufacturing a polishing pad using the urethane resin composition, for example, the main agent (i) or the hardener (ii) may be contained in a hollow state having a diameter of 20 to 120 μm in advance. A method of mixing plastic spheres (microballoons) with a base liquid and a hardener to obtain a molded article containing hollow plastic spheres, followed by slicing into a thin sheet.

The polishing pad of the present invention obtained by the above method has an excellent polishing rate, and among the materials to be polished using the polishing pad of the present invention, it is possible to obtain a polishing material with less occurrence of scratches and excellent smoothness of the surface of the material to be polished. Grinders.

Therefore, the polishing pad obtained by using the urethane resin composition for a polishing pad of the present invention is applied to a glass substrate for a liquid crystal display (LCD), a glass substrate for a hard disk (HDD), a glass disk for a recording device, and optical use. Lenses, silicon wafers, semiconductor elements, and other high-precision polishing processes that require a high degree of surface flatness and in-plane uniformity are useful, and polishing of materials to be polished with a Vickers hardness of 1500 or less is useful, especially for silicon Wafer grinding is useful.

The Vickers hardness is a type of indentation hardness, and a rigid body (indenter) made of diamond is pressed into the test object, and the area of the indentation completed at this time is used for judgment. As a test method, there is JIS-Z-2244. The various approximated Vickers hardnesses are as follows.

Silicon carbide (SiC): 2300 ~ 2500, sapphire: 2300, silicon: 1050, quartz glass: 950, various glass: 500 ~ 700.

As a polishing method using the polishing pad of the present invention, for example, in the case of polishing a silicon wafer, a slurry (a weakly alkaline colloidal silicon dioxide aqueous solution) is dropped on the polishing pad, and the object to be polished is pressed. A method of crimping a pad that is fused to the slurry, and rotating (rotating) the surface of the pad to which the pad is attached, and polishing the pad. (CMP polishing method using free abrasive particles).

    [Example]    

Hereinafter, the present invention will be specifically described based on examples and comparative examples.

    (Synthesis Example 1: Synthesis of Urethane Prepolymer (A1))    

In a 5-liter 4-neck round bottom flask equipped with a nitrogen introduction tube, a cooling condenser, a thermometer, and a stirrer, 2366 parts by mass of toluene diisocyanate (TDI-80) was added, and stirring was started. Next, 2028 parts of polybutylene glycol (number average molecular weight: 1000) was added and mixed, and the reaction was performed at 80 ° C. for 3 hours under a nitrogen atmosphere. Next, 15 parts by mass of a polysiloxane compound ("X-22-176DX" manufactured by Shin-Etsu Chemical Industry Co., Ltd .; single-ended silicone diol, number average molecular weight 3262) was added and mixed, and the temperature was 80 ° C under a nitrogen atmosphere. The reaction was performed for 3 hours. Next, 591 parts by mass of diethylene glycol was reacted for 3 hours while paying attention to heat generation, and an isocyanate-terminated urethane prepolymer (A1) having an NCO equivalent of 420 was obtained.

    (Synthesis example 2: Synthesis of urethane prepolymer (A2))    

In a 5-liter 4-neck round bottom flask equipped with a nitrogen introduction tube, a cooling condenser, a thermometer, and a stirrer, 2366 parts by mass of toluene diisocyanate (TDI-80) was added, and stirring was started. Next, 2044 parts by mass of butylene glycol (number-average molecular weight: 1000) was added and mixed, and the reaction was performed at 80 ° C for 3 hours in a nitrogen atmosphere. Next, 590 parts by mass of diethylene glycol was reacted for 3 hours while paying attention to heat generation, and an isocyanate-terminated urethane prepolymer (A2) having an NCO equivalent of 420 was obtained.

    (Synthesis Example 3: Synthesis of Urethane Prepolymer (A3))    

The isocyanate-terminated urethane prepolymer (A3) was obtained in the same manner only by changing the blending number of Synthesis Example 1. Furthermore, 2366 parts by mass of toluene diisocyanate, 1936 parts by mass of polybutylene glycol, and 100 parts by mass of a polysiloxane compound ("X-22-176DX" manufactured by Shin-Etsu Chemical Industry Co., Ltd. were added; Terminal silicone diol, number average molecular weight 3262), 598 parts by mass of diethylene glycol.

    (Example 1: Production of polishing pad (P1))    

The isocyanate-terminated urethane prepolymer (A1) obtained in Synthesis Example 1 was adjusted to a temperature of 80 ° C. as component A. Next, 3,3'-dichloro-4,4'-diaminobenzyl methane (hereinafter simply referred to as "MBOCA") was melted and tempered at 120 ° C as component B.

Further, 100 parts by mass of polypropylene glycol (number-average molecular weight 3000, number of functional groups: 3, hereinafter simply referred to as "PPG3000"), 7.0 parts by mass of ion-exchanged water, and 0.6 parts by mass of bis (dimethyl) were sufficiently stirred and mixed. A mixture of amine ethyl) ether and 4 parts by mass of a silicon foam stabilizer ("SH-193" manufactured by Dow Corning Toray Co., Ltd.) was temperature-controlled at 35 ° C as a component C (C mixture).

Next, each of the three grooves of the hybrid elastomer casting machine (EA-404 type modification, manufactured by Toho Machinery Industry Co., Ltd.) was added with the aforementioned components A, B, and C, respectively. Next, mix in a casting mold (internal size 250 × 250 × 50mm) whose temperature is adjusted to 80 ° C., with the R value = 0.9 and the blending ratio of A component / B component / C component = 77.9 / 18.2 / 3.9 (weight ratio). Spit it out. In addition, the injection amount was 1875 g and injected.

‧Discharge amount = 7000g / min

‧Mixer speed = 5000rpm (Mixer: gear type)

Immediately after that, the lid of the mold was closed, and after holding at 80 ° C for 45 minutes, the ingot-molded product was taken out. Further, the obtained ingot-molded article was post-cured at 110 ° C. for 16 hours.

The obtained ingot-molded article was cut with a microtome to a thickness of 1.5 mm to obtain a thin-shaped polishing pad (P1).

    (Comparative Example 1: Production of polishing pad (P'1))    

The urethane prepolymer (A2) obtained in Synthesis Example 2 was used in place of the urethane prepolymer (A1) used in Example 1 except that the same procedure was performed as in Example 1 to obtain a mill. Pad (P'1).

    (Comparative Example 2: Production of a polishing pad (P'2))    

The urethane prepolymer (A3) obtained in Synthesis Example 3 was used in place of the urethane prepolymer (A1) used in Example 1, except that the same procedure was performed as in Example 1 to obtain a mill. Pad (P'2).

The following evaluations were performed using the polishing pads obtained in the above examples and comparative examples.

    [Evaluation method of grinding rate]    

The polishing pads obtained in the examples and comparative examples were attached to one side of the double-sided tape, and the surface plate of the grinder was attached to the other side of the double-sided tape.

Grinder: FAM 18 GPAW (Surface flat plate diameter made by Speed Fam Co., Ltd. = 457m water-cooled)

    Grinding conditions:    

(Pre-pad treatment) The surface of the pad was treated with a diamond dresser (# 100) (flattening and polishing of the pad) until the lines drawn in the vertical and horizontal directions at 2 cm intervals with a red pencil disappeared. Water supply 200ml / min

(Grinding target) 4 inch single crystal silicon wafer thickness: 540μm

(Attachment method) ceramic block / microporous suede pad (water-absorbent) silicon wafer

(Mill cooling water) 20 ℃

(Slurry) Colloidal silicon dioxide solution NITTA HAAS Co., Ltd. "N6501" diluted 20 times

(Slurry flow) 100ml / min (circulating)

(Surface plate speed) 50rpm (traction type)

(Grinding pressure) 18, 30, 42kPa

(Grinding time) 20 minutes

(Polishing rate) Calculated from the weight difference of the polyurethane polishing pad before and after polishing.

That is, the 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 ) × area of silicon wafer (cm ² ) × polishing time (min))

Density of single crystal silicon = 2.329g / cm ³

Area of silicon wafer = 20.4cm ²

    [Scratch (smoothness) evaluation method using atomic force microscope AFM]    

AFM was used to observe the surface of the silicon wafer (the final polishing condition was 42 kPa, 20 minutes) after the above polishing rate evaluation, and the average surface roughness (Ra), maximum height difference (PV), and n-point average roughness were calculated. (Rz).

Machine: SPA300 / SPI3800N (made by Hitachi High-Tech Science Co., Ltd.)

(Measurement mode) DFM

(Scanner) 80μm scanner

(Cantilever) SI-DF20

(Measured area) 5 × 5μm ²

Table 1 shows the evaluation results of the polishing pads (P1), (P'1), and (P'2) obtained in Example 1, Comparative Example 1, and Comparative Example 2.

AFM observation results of the surface of the silicon wafer polished using the polishing pad (P1) obtained in Example 1 are shown in FIG. 1.

AFM observation results of the surface of the silicon wafer polished using the polishing pad (P'1) obtained in Comparative Example 1 are shown in Fig. 2.

AFM observation results of the surface of the silicon wafer polished using the polishing pad (P'2) obtained in Comparative Example 2 are shown in Fig. 3.

Example 1 using the polishing pad of the present invention has an excellent polishing rate, and meanwhile, in the evaluation of scratches of the material to be polished using AFM, the average surface roughness (Ra), maximum height difference (PV), and n-point average The value of the roughness (Rz) was also good, and it was confirmed that the surface of the material to be polished after polishing has high smoothness and few scratches.

In contrast, Comparative Example 1 is an example of a single-ended silicone diol that does not use a polyol as a raw material for the urethane prepolymer, that is, the one represented by the general formula (1) of the present invention is not used. Examples of polysiloxane compounds. Although the polishing rate is excellent, the values of average surface roughness (Ra), maximum height difference (PV), and n-point average roughness (Rz) in the scratch evaluation of the material to be polished using AFM are significantly insufficient, and It was confirmed that the surface of the material to be polished after polishing was low in smoothness and a lot of scratches were generated.

In addition, Comparative Example 2 is an example of using a single-ended silicone diol of a polyhydric alcohol as a raw material of the urethane prepolymer outside the scope of the present invention, that is, a case where the present invention is used outside the scope of the present invention Examples of the polysiloxane compound represented by the general formula (1). The polishing rate is insufficient, and in the evaluation of the scratch of the material to be polished using AFM, the values of average surface roughness (Ra), maximum height difference (PV), and n-point average roughness (Rz) are also significantly insufficient, and It was confirmed that the surface of the material to be polished after polishing was low in smoothness and a lot of scratches were generated.

Claims (6)

A polishing pad comprising a foamed hardened product of a urethane resin composition of a main agent (i) and a hardener (ii), the main agent (i) comprising a general formula ( 1) The isocyanate group-containing urethane prepolymer (A) as a reactant of the polyol (a1) and the polyisocyanate (a2) shown in the polysiloxane compound is characterized in that: The proportion of the polysiloxane compound in the raw material of the ester prepolymer (A) is 1% by mass or less; (In formula (1), R ¹ and R ^{3 are} each independently and represent an alkyl group having 1 to 5 carbon atoms, R ² represents an alkylene group having 1 to 5 carbon atoms, and n represents a repeating unit of 1 to 200 average value).     The polishing pad according to claim 1, wherein the polyol (a1) further comprises polybutylene glycol.         For example, the polishing pad of claim 1 or 2, wherein the polishing pad is an abrasive used for a material to be polished having a Vickers hardness of 1500 or less.     A method for manufacturing a polishing pad, comprising: mixing a main component (a) containing an isocyanate group-containing urethane prepolymer (A) obtained by reacting a polyol (a1) and a polyisocyanate (a2); i), a hardening agent (ii), and a urethane resin composition containing a foaming agent (iii) containing water (B), poured into a mold, and foamed and hardened to obtain a foamed molded product, Next, the foamed molded article is taken out from the mold and sliced into a sheet shape, wherein the polyol (a1) includes a polysiloxane compound represented by the following general formula (1); (In formula (1), R ¹ and R ^{3 are} each independently and represent an alkyl group having 1 to 5 carbon atoms, R ² represents an alkylene group having 1 to 5 carbon atoms, and n represents a repeating unit of 1 to 200 average value). A method for manufacturing a polishing pad, which comprises an isocyanate group obtained by reacting a polyol (a1) and a polyisocyanate (a2) containing a polysiloxane compound represented by the following general formula (1): The main agent (i) of the urethane prepolymer (A) is mechanically foamed to obtain a foaming agent (i '), and the foaming agent (i') and a curing agent (ii) are mixed and contained. ) A urethane resin composition, poured into a mold, and hardened to obtain a foamed molded product, and then the foamed molded product is taken out from the mold and sliced into a sheet shape; (In formula (1), R ¹ and R ^{3 are} each independently and represent an alkyl group having 1 to 5 carbon atoms, R ² represents an alkylene group having 1 to 5 carbon atoms, and n represents a repeating unit of 1 to 200 average value).     A grinding method for a material to be polished having a Vickers hardness of 1500 or less, which uses a polishing pad as described in claim 1.