Polishing pad and method for manufacturing polished workpiece

Abstract

To provide a polishing pad that can reduce occurrence of scratches and a manufacturing method for a polished work-piece.SOLUTION: The polishing pad comprises a polyurethane sheet as a polishing layer. In dynamic viscoelasticity measurement that is performed in a submerged state under the condition that a frequency is 1.6 Hz and a temperature is in a range of 20-100°C, the polyurethane sheet has a peak of loss tangent tanδ in a range of 40-60°C.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polishing pad and a method for manufacturing a polished object.

Background Art

[0002] On the surface (processing surface) of materials such as semiconductor devices and electronic components, particularly thin substrates (objects to be polished) such as Si substrates (silicon wafers), substrates for hard disks, glass, and substrates for LCDs (liquid crystal displays), chemical mechanical polishing using a polishing slurry and a polishing pad is performed.

[0003] As a polishing pad used for such polishing, for example, for the purpose of reducing dishing, a polishing pad provided with a polishing layer having a ratio of E' at 30°C to 90°C of about 1 to 3.6 is used (Patent Document 1), and also for the purpose of achieving both planarization performance and low defect performance rate, a polymer material having a porosity of 0.1% by volume, a KEL energy loss coefficient of 385 to 750 l / Pa at 40°C and 1 rad / sec, and an elastic modulus E' of 100 to 400 MPa at 40°C and 1 rad / sec is used as a polishing layer. It is known to use a polishing pad provided with (Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when the polishing pads described in Patent Documents 1 and 2 above are used, it cannot be said that the surface quality of the obtained object to be polished is high, and for example, it has been found that scratches and the like occur.

[0006] The present invention has been made in view of the above problems, and an object thereof is to provide a polishing pad capable of reducing the occurrence of scratches and a method for manufacturing a polished article.

Means for Solving the Problems

[0007] As a result of intensive studies to solve the above problems, the inventors of the present invention have found that when dynamic viscoelasticity measurement is performed under immersion (in water) conditions, the above problems can be solved by using a polyurethane sheet having a peak of tanδ obtained in a specific temperature range as a polishing layer, and thus the present invention has been completed.

[0008] That is, the present invention is as follows. 〔1〕 A polishing pad comprising a polyurethane sheet as a polishing layer, In the dynamic viscoelasticity measurement performed under immersion conditions at a frequency of 1.6 Hz and a temperature range of 20 to 100 °C, the polyurethane sheet has a peak of loss tangent tanδ in the range of 40 to 60 °C. Polishing pad. 〔2〕 The value of the peak of the loss tangent tanδ is 0.15 to 0.35. The polishing pad according to 〔1〕. 〔3〕 In the dynamic viscoelasticity measurement performed under immersion conditions at a frequency of 1.6 Hz and a temperature range of 20 to 100 °C, the value of the loss elastic modulus E'' of the polyurethane sheet at 40 °C is 21 MPa or more. The polishing pad according to 〔1〕 or 〔2〕. 〔4〕 In the dynamic viscoelasticity measurement performed under immersion conditions at a frequency of 1.6 Hz and a temperature range of 20 to 100 °C, the difference A between the loss tangents tanδ of the polyurethane sheet at 60 °C and 70 °C is smaller than the difference B between the loss tangents tanδ at 50 °C and 60 °C and the difference C between the loss tangents tanδ at 70 °C and 80 °C. The polishing pad according to any one of 〔1〕 to 〔3〕. 〔5〕 The polyurethane sheet contains a polyurethane resin and hollow fine particles dispersed in the polyurethane resin. The polishing pad according to any one of [1] to [4]. [6] Having a polishing step of polishing an object to be polished using the polishing pad according to any one of [1] to [5] in the presence of a polishing slurry. A method for manufacturing a polished product. [Advantages of the Invention]

[0009] According to the present invention, it is possible to provide a polishing pad and a method for manufacturing a polished product capable of reducing the occurrence of scratches. [Brief Description of the Drawings]

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0011] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail, but the present invention is not limited thereto, and various modifications are possible without departing from the gist thereof.

[0012] [Polishing Pad] The polishing pad of the present embodiment includes a polyurethane sheet as a polishing layer, and in a water-soaked state, in a dynamic viscoelasticity measurement performed under the conditions of a frequency of 1.6 Hz and a temperature of 20 to 100 °C, the polyurethane sheet has a peak of loss tangent tanδ in the range of 40 to 60 °C.

[0013] (Loss tangent tanδ) The loss tangent tanδ is a value represented by the ratio of the loss elastic modulus E'' (viscous component) to the storage elastic modulus E' (elastic component), and is an index indicating the balance between the elasticity and viscosity exhibited by the substance to be measured under the measurement conditions. It is known that the loss tangent tanδ varies depending on whether the substance to be measured is in a dry state or a water-soaked state, and also varies depending on the frequency during measurement. In the present embodiment, by controlling the dynamic viscoelasticity of the polishing layer in the dynamic process during polishing within a predetermined range, the contact state with the workpiece to be polished during polishing is made better, and furthermore, by suppressing the stubborn pressing of the polishing debris generated by polishing, the generation of scratches is suppressed. More specifically, under the polishing conditions, by making a state in which the loss elastic modulus E'' (viscous component) becomes more dominant than the storage elastic modulus E' (elastic component), the generation of scratches can be suppressed.

[0014] Under the polishing conditions, the polishing layer is in a state wetted by the slurry and contacts the workpiece by a predetermined polishing operation at a predetermined temperature. Therefore, in the present embodiment, it is defined that the polishing layer has a peak of loss tangent tanδ in the temperature range (40 to 60 °C) equivalent to the temperature of the polishing process in a dynamic viscoelasticity measurement performed under the conditions of a frequency of 1.6 Hz and a temperature of 20 to 100 °C in a water-soaked state.

[0015] The peak temperature of the loss tangent tanδ is 40 to 60 °C, preferably 40 to 56 °C, and more preferably 40 to 52 °C. When the peak of the loss tangent tanδ is within the above temperature range, a state in which the loss elastic modulus E'' (viscous component) becomes more dominant than the storage elastic modulus E' (elastic component) is exhibited in the temperature range equivalent to the temperature of the polishing process, and the generation of scratches is suppressed.

[0016] Here, "in the dynamic viscoelasticity measurement performed under the conditions of 20 to 100°C, having a peak of loss tangent tanδ in the range of 40 to 60°C" means that the maximum value of loss tangent tanδ in the range of 20 to 100°C is in the range of 40 to 60°C. In addition to this, in the present embodiment, "peak" refers to a temperature range of the temperature ±5°C at which the maximum value is obtained, and the difference between the maximum value and the minimum value is 0.05 or more, and finer fluctuations up and down due to noise, etc. are not interpreted as peaks.

[0017] The peak value of loss tangent tanδ is preferably 0.15 to 0.35, more preferably 0.20 to 0.35, and even more preferably 0.22 to 0.35. When the peak value of loss tangent tanδ is within the above range, in a temperature range equivalent to the temperature of the polishing process, a state where the loss elastic modulus E'' (viscous component) is more dominant than the storage elastic modulus E' (elastic component) is more effectively expressed, and the occurrence of scratches tends to be more suppressed.

[0018] Also, in the immersed state, in the dynamic viscoelasticity measurement performed under the conditions of a frequency of 1.6 Hz and 20 to 100°C, the value of the loss elastic modulus E'' of the polyurethane sheet at 40°C is preferably 21 MPa or more, more preferably 22 to 45 MPa, and even more preferably 23 to 40 MPa. When the value of the loss elastic modulus E'' at 40°C is within the above range, in a temperature range equivalent to the temperature of the polishing process, a state where the loss elastic modulus E'' (viscous component) is more dominant than the storage elastic modulus E' (elastic component) is more effectively expressed, and the occurrence of scratches tends to be more suppressed.

[0019] Furthermore, in the dynamic viscoelasticity measurement conducted under the conditions of a frequency of 1.6 Hz and a temperature range of 20 to 100°C in a submerged state, it is preferable that the difference A between the loss tangents tanδ at 60°C and 70°C of the polyurethane sheet is smaller than the difference B between the loss tangents tanδ at 50°C and 60°C and the difference C between the loss tangents tanδ at 70°C and 80°C. That is, as shown in FIG. 1 to be described later, it is preferable that the chart of the loss tangent tanδ has a shoulder on the higher temperature side than the peak. By having a shoulder on the higher temperature side in this way, a relatively high tanδ (in water) is maintained even on the higher temperature side than the peak. Therefore, in a wider temperature range, a state can be achieved in which the loss elastic modulus E'' (viscous component) is more dominant than the storage elastic modulus E' (elastic component). As a result, in the polishing process, even if a locally high-temperature portion is generated due to frictional heat or the like, it is possible to suppress the storage elastic modulus E' (elastic component) from becoming dominant in that portion, and the occurrence of scratches tends to be more suppressed.

[0020] The difference A between the loss tangents tanδ at 60°C and 70°C of the polyurethane sheet is preferably 0.010 to 0.035, more preferably 0.010 to 0.030, and even more preferably 0.012 to 0.028. Also, the difference B between the loss tangents tanδ at 50°C and 60°C is preferably 0.035 to 0.060, more preferably 0.038 to 0.050, and even more preferably 0.040 to 0.045. Furthermore, the difference C between the loss tangents tanδ at 70°C and 80°C is preferably 0.055 to 0.095, more preferably 0.060 to 0.090, and even more preferably 0.065 to 0.085.

[0021] The difference between the difference A indicating the slope of the loss tangent tanδ at 60°C and 70°C and the difference B indicating the slope of the loss tangent tanδ at 50°C and 60°C is preferably from 0.010 to 0.040, more preferably from 0.014 to 0.035, and even more preferably from 0.016 to 0.030. Also, the difference between the difference A indicating the slope of the loss tangent tanδ at 60°C and 70°C and the difference C indicating the slope of the loss tangent tanδ at 70°C and 80°C is preferably from 0.030 to 0.080, more preferably from 0.040 to 0.070, and even more preferably from 0.050 to 0.060.

[0022] The dynamic viscoelasticity measurement of this embodiment can be carried out according to a conventional method. In the dynamic viscoelasticity measurement in a water-soaked state, a polished layer immersed in water at a temperature of 23°C for 3 days is used as a sample, and the sample is measured while being immersed in water. Examples of a dynamic viscoelasticity measuring device capable of such measurement include DMA8000 manufactured by PerkinElmer Japan Co., Ltd. Regarding other conditions, although not particularly limited, measurement can be carried out under the conditions described in the examples.

[0023] (Polyurethane sheet) As the polished layer having the above characteristics, a polyurethane sheet is used. The polyurethane resin constituting the polyurethane sheet is not particularly limited, and examples thereof include polyester-based polyurethane resins, polyether-based polyurethane resins, and polycarbonate-based polyurethane resins. These may be used alone or in combination of two or more.

[0024] Such polyurethane resins are not particularly limited as long as they are reaction products of a urethane prepolymer and a curing agent, and various known ones can be applied. Here, the urethane prepolymer is not particularly limited, but for example, an adduct of hexamethylene diisocyanate and hexanetriol; an adduct of 2,4-tolylene diisocyanate and plenzcatechol; an adduct of tolylene diisocyanate and hexanetriol; an adduct of tolylene diisocyanate and trimethylolpropane; an adduct of xylylene diisocyanate and trimethylolpropane; an adduct of hexamethylene diisocyanate and trimethylolpropane; and an adduct of isocyanuric acid and hexamethylene diisocyanate can be mentioned. In addition, isocyanate group-containing compounds prepared by the reaction of polyisocyanate compounds and polyol compounds other than these, and various commercially available urethane prepolymers may be used. The urethane prepolymer may be used alone or in combination of two or more.

[0025] The polyisocyanate compound used in the isocyanate group-containing compound is not particularly limited as long as it has two or more isocyanate groups in the molecule. For example, diisocyanate compounds having two isocyanate groups in the molecule include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,6-tolylene diisocyanate (2,6-TDI), 2,4-tolylene diisocyanate (2,4-TDI), naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate (MDI), 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI), 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3,3'-dimethyl- Examples of the diisocyanate include diphenylmethane-4,4'-diisocyanate, xylylene-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, propylene-1,2-diisocyanate, butylene-1,2-diisocyanate, cyclohexylene-1,2-diisocyanate, cyclohexylene-1,4-diisocyanate, p-phenylene diisothiocyanate, xylylene-1,4-diisothiocyanate, and ethylidine diisothiocyanate. As the polyisocyanate compound, a diisocyanate compound is preferred, and among them, 2,4-TDI, 2,6-TDI and MDI are more preferred, and 2,4-TDI and 2,6-TDI are particularly preferred. These polyisocyanate compounds may be used alone or in combination of two or more polyisocyanate compounds.

[0026] The polyisocyanate compound preferably contains 2,4-TDI and / or 2,6-TDI, more preferably contains 2,4-TDI and 2,6-TDI. It is even more preferable that the polyisocyanate compound consists solely of 2,4-TDI and 2,6-TDI. The mass ratio of 2,4-TDI to 2,6-TDI is preferably 100:0 to 50:50, more preferably 90:10 to 60:40, even more preferably 90:10 to 70:30, and even more preferably 80:20.

[0027] Examples of the polyol compound used in the isocyanate group-containing compound include diol compounds such as ethylene glycol, diethylene glycol (DEG), and butylene glycol, triol compounds, etc.; polyether polyol compounds such as polypropylene glycol (PPG) and poly(oxytetramethylene) glycol (PTMG); polyester polyol compounds such as the reaction product of ethylene glycol and adipic acid and the reaction product of butylene glycol and adipic acid; polycarbonate polyol compounds, polycaprolactone polyol compounds, etc. Further, trifunctional propylene glycol added with ethylene oxide can also be used. Among these, PTMG is preferable, and it is also preferable to use a combination of PTMG and DEG. The number average molecular weight (Mn) of PTMG is preferably 500 to 2000, more preferably 500 to 1300, even more preferably 500 to 1000, and even more preferably 500 to 800. The number average molecular weight can be measured by gel permeation chromatography (GPC). In addition, when measuring the number average molecular weight of the polyol compound from the polyurethane resin, it can also be estimated by GPC after decomposing each component by a conventional method such as amine decomposition. The polyol compound may be used alone or in combination of a plurality of polyol compounds.

[0028] The NCO equivalent of the urethane prepolymer is preferably 300 to 700, more preferably 350 to 600, and even more preferably 400 to 500. Note that the "NCO equivalent" is obtained by "(mass parts of polyisocyanate compound + mass parts of polyol compound) / [(number of functional groups per molecule of polyisocyanate compound × mass parts of polyisocyanate compound / molecular weight of polyisocyanate compound)-(number of functional groups per molecule of polyol compound × mass parts of polyol compound / molecular weight of polyol compound)]", and is a numerical value indicating the molecular weight of the urethane prepolymer per NCO group.

[0029] The curing agent is not particularly limited, but examples thereof include ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 4-methyl-2,6-bis(methylthio)-1,3-benzenediamine, 2-methyl-4,6-bis(methylthio)-1,3-benzenediamine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 2,2-bis[3-(isopropyl)methyl] ... polyamine compounds such as 2,2-bis[3-(1-methylpropylamino)-4-hydroxyphenyl]propane, 2,2-bis[3-(1-methylpentylamino)-4-hydroxyphenyl]propane, 2,2-bis[3-(1-methylpentylamino)-4-hydroxyphenyl]propane, 2,2-bis(3,5-diamino-4-hydroxyphenyl)propane, 2,6-diamino-4-methylphenol, trimethylethylene bis-4-aminobenzoate, and polytetramethylene oxide-di-p-aminobenzoate; ethylene glycol Coal, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol , 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerin, trimethylolpropane, trimethylolethane, trimethylolmethane, poly(oxytetramethylene) glycol, polyethylene glycol, and polypropylene glycol.Furthermore, the polyvalent amine compound may have a hydroxyl group, and examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine.

[0030] As the polyvalent amine compound, a diamine compound is preferred, and 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) is particularly preferred. Examples of MOCA include PANDEX E (manufactured by DIC Corporation) and Iharacuamine MT (manufactured by Kumiai Chemical Co., Ltd.). As the polyhydric alcohol compound, polypropylene glycol is preferred, more preferably polypropylene glycol having a number average molecular weight of 1000 to 3000, and even more preferably polypropylene glycol having a number average molecular weight of 1500 to 2500. The curing agent may be used alone or in combination of two or more types.

[0031] The curing agent is preferably added in an amount of 10 to 60 parts by mass, more preferably 20 to 50 parts by mass, and even more preferably 20 to 40 parts by mass, per 100 parts by mass of the urethane prepolymer.

[0032] The peak temperature of the loss tangent tanδ can be adjusted by the molecular weight (degree of polymerization) of the urethane prepolymer and the combination of the urethane prepolymer and curing agent. From this perspective, for example, the components are preferably mixed so that the R value, which is the equivalent ratio of the active hydrogen groups (amino groups and hydroxyl groups) present in the curing agent to the isocyanate groups present at the terminal of the isocyanate group-containing compound as the urethane prepolymer, is 0.70 to 1.30, more preferably 0.75 to 1.20, even more preferably 0.80 to 1.10, still more preferably 0.80 to 1.00, and even more preferably 0.85 to 0.95.

[0033] In addition, the polyurethane sheet is preferably a foamed polyurethane sheet having bubbles. The bubbles in the foamed polyurethane sheet are classified into closed cells in which a plurality of bubbles exist independently and open cells in which a plurality of bubbles are connected by through-holes, depending on their form. Among these, the polyurethane sheet of the present embodiment preferably has closed cells, and more preferably is a polyurethane sheet containing a polyurethane resin and hollow fine particles dispersed in the polyurethane resin. By using hollow fine particles, it tends to be easier to adjust the peak temperature of the loss tangent tanδ.

[0034] A polyurethane sheet having closed cells can be formed by using hollow fine particles having an outer shell and being hollow inside. As the hollow fine particles, commercially available ones may be used, or those obtained by synthesizing them by a conventional method may be used. The material of the outer shell of the hollow fine particles is not particularly limited. For example, polyvinyl alcohol, polyvinyl pyrrolidone, poly(meth)acrylic acid, polyacrylamide, polyethylene glycol, polyhydroxy ether acrylate, maleic acid copolymer, polyethylene oxide, polyurethane, poly(meth)acrylonitrile, polyvinylidene chloride, polyvinyl chloride, and organosilicon-based resins, and copolymers obtained by combining two or more of the monomers constituting these resins can be mentioned. Examples of commercially available hollow fine particles include, but are not limited to, Expancel series (trade name of products manufactured by Akzo Nobel), Matsumoto Microsphere (trade name of products manufactured by Matsumoto Yushi Co., Ltd.), and the like.

[0035] The shape of the hollow microparticles in the polyurethane sheet is not particularly limited and may be, for example, spherical or substantially spherical. The average particle diameter of the hollow microparticles is not particularly limited, but is preferably 5 to 200 μm, more preferably 5 to 80 μm, still more preferably 5 to 50 μm, and particularly preferably 5 to 35 μm. By using such hollow microparticles, the peak temperature of the loss tangent tanδ can also be adjusted. The average particle diameter can be measured by a laser diffraction particle size distribution measuring device (for example, Mastersizer-2000 manufactured by Malvern Panalytical Ltd.).

[0036] The hollow microparticles are preferably added in an amount of 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass, still more preferably 1 to 3 parts by mass, based on 100 parts by mass of the urethane prepolymer.

[0037] In addition to the above components, a conventionally used foaming agent may be used in combination with the hollow microparticles within a range that does not impair the effects of the present invention, or a gas that is non-reactive with respect to each of the above components may be blown in during the following mixing step. Examples of the foaming agent include water and a foaming agent mainly composed of a hydrocarbon having 5 or 6 carbon atoms. Examples of the hydrocarbon include linear hydrocarbons such as n-pentane and n-hexane, and alicyclic hydrocarbons such as cyclopentane and cyclohexane. In addition to the above components, a known foam stabilizer, flame retardant, colorant, plasticizer, etc. may be added.

[0038] The method for producing a polyurethane sheet is not particularly limited, but examples include a method in which a urethane prepolymer and a curing agent are reacted to form a polyurethane resin block and then a sheet is cut from the resulting polyurethane resin block. In the mixing step, the urethane prepolymer and the curing agent are fed into a mixer and stirred and mixed. Furthermore, when hollow microparticles are used, a polyurethane resin block incorporating the hollow microparticles can be obtained by mixing the urethane prepolymer, the curing agent, and the hollow microparticles. While there are no particular limitations on the order of mixing, it is preferable to first mix the urethane prepolymer and the hollow microparticles and then feed the curing agent into the mixer. In this way, a mixed solution for the polyurethane resin block is prepared. The mixing step is carried out under heated conditions at a temperature that ensures the fluidity of each of the above components.

[0039] For example, a solution of a urethane prepolymer (e.g., an isocyanate group-containing compound) containing hollow microparticles heated to 30 to 90°C is charged with a curing agent in a temperature-controllable jacketed mixer, and stirred at 30 to 130°C. If necessary, the mixed solution may be transferred to a jacketed tank equipped with a stirrer and aged. The stirring time is adjusted appropriately depending on the number of mixer teeth, rotation speed, clearance, etc., but is, for example, 0.1 to 60 seconds.

[0040] In the molding process, the polyurethane resin block mixture prepared in the mixing process is poured into a mold preheated to 30 to 100°C and cured at approximately 100 to 150°C for 10 minutes to 5 hours to form a polyurethane resin block. During this process, the urethane prepolymer reacts with the curing agent to form a polyurethane resin, and the mixture hardens with bubbles and / or hollow microparticles dispersed in the polyurethane resin. This results in a polyurethane resin block containing numerous roughly spherical bubbles.

[0041] The polyurethane resin block obtained by the shaping process is then sliced into a sheet form to form a polyurethane sheet. By being sliced, openings will be provided on the sheet surface. At this time, in order to form openings on the surface of the polishing layer that is excellent in wear resistance and not easily clogged, it may be aged at 30 to 150 °C for about 1 hour to 24 hours.

[0042] The polishing layer having the polyurethane sheet thus obtained is then attached with a double-sided tape to the surface opposite to the polishing surface of the polishing layer, cut into a predetermined shape, preferably a disc shape, and completed as the polishing pad of the present embodiment. There is no particular limitation on the double-sided tape, and it can be arbitrarily selected and used from the double-sided tapes known in the art.

[0043] Also, the polishing pad of the present embodiment may have a single-layer structure composed only of a polishing layer, or may be composed of a multi-layer in which another layer (lower layer, support layer) is bonded to the surface opposite to the polishing surface of the polishing layer. The characteristics of the other layer are not particularly limited. When a layer softer than the polishing layer (with a smaller A hardness or D hardness) is bonded to the surface opposite to the polishing layer, the polishing flatness is further improved. On the other hand, when a layer harder than the polishing layer (with a larger A hardness or D hardness) is bonded to the surface opposite to the polishing layer, the polishing rate is further improved.

[0044] In the case of having a multi-layer structure, the plurality of layers may be bonded and fixed to each other using a double-sided tape, an adhesive, etc., with pressure applied if necessary. There is no particular limitation on the double-sided tape or adhesive used at this time, and it can be arbitrarily selected and used from the double-sided tapes and adhesives known in the art.

[0045] Furthermore, the polishing pad of the present embodiment may, if necessary, grind the front and / or back surface of the polishing layer, or perform groove processing, embossing, or hole processing (punching) on the surface. The base material and / or the adhesive layer may be bonded to the polishing layer, and a light transmission portion may be provided. There is no particular limitation on the method of grinding, and it can be ground by a known method. Specifically, grinding with sandpaper can be mentioned. There is no particular limitation on the shape of the groove processing and embossing, and examples of the shape include a lattice shape, a concentric circle shape, and a radial shape.

[0046] 〔Method for manufacturing a polished article〕 The method for manufacturing a polished article of the present embodiment includes a polishing step of polishing an object to be polished using the above polishing pad in the presence of a polishing slurry to obtain a polished article. The polishing step may be a primary polishing (rough polishing), a finish polishing, or a combination of both. Among these, the polishing pad of the present embodiment is preferably used for chemical mechanical polishing. Hereinafter, the method for manufacturing a polished article of the present embodiment will be described by taking chemical mechanical polishing as an example, but the method for manufacturing a polished article of the present embodiment is not limited thereto.

[0047] In this manufacturing method, while supplying the polishing slurry, the object to be polished is pressed against the polishing pad side by the holding platen, and the holding platen and the polishing platen are rotated relative to each other, so that the processed surface of the object to be polished is polished by chemical mechanical polishing (CMP) with the polishing pad. The holding platen and the polishing platen may rotate in the same direction or in different directions at different rotational speeds. Further, the object to be polished may be polished while moving (rotating) inside the frame portion during the polishing process.

[0048] The polishing slurry may contain water, chemical components such as oxidizing agents typified by hydrogen peroxide, additives, abrasive grains (polishing particles; for example, SiC, SiO2, Al2O3, CeO2), etc., depending on the object to be polished, polishing conditions, etc.

[0049] In addition, the object to be polished is not particularly limited, and examples thereof include materials such as semiconductor devices and electronic components, and particularly, thin substrates (objects to be polished) such as Si substrates (silicon wafers), substrates for hard disks, glass, and substrates for LCDs (liquid crystal displays). Among these, the method for manufacturing a polished product according to the present embodiment can be suitably used as a method for manufacturing a semiconductor device or the like on which a metal layer such as an oxide layer or copper is formed.

Example

[0050] Hereinafter, the present invention will be described more specifically using examples and comparative examples. The present invention is not limited by the following examples.

[0051] 〔Example 1〕 To 100 parts of a urethane prepolymer having an NCO equivalent of 460 obtained by reacting 2,4-tolylene diisocyanate (TDI), poly(oxytetramethylene) glycol (PTMG) having a number average molecular weight of 650, and diethylene glycol (DEG), 2.8 parts of expanded hollow fine particles having a particle size of 15 to 25 μm (average particle size: 20 μm) in which the shell portion is made of an acrylonitrile-vinylidene chloride copolymer and isobutane gas is encapsulated in the shell were added and mixed to obtain a urethane prepolymer mixture. The obtained urethane prepolymer mixture was charged into a first liquid tank and kept warm at 80°C. Separately from the first liquid tank, 25.5 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-o-chloroaniline) (MOCA) and 8.5 parts of polypropylene glycol were placed in a second liquid tank, heated and melted at 120°C and mixed, and further degassed under reduced pressure to obtain a curing agent melt.

[0052] Next, the liquids in the first liquid tank and the second liquid tank were injected from the respective inlets of a mixer having two inlets and stirred and mixed to obtain a mixture. At this time, the mixing ratio was adjusted so that the R value representing the equivalent ratio of the amino group and the hydroxyl group present in the curing agent to the isocyanate group present at the terminal in the urethane prepolymer was 0.90.

[0053] The obtained mixture was poured into a mold preheated to 100 °C and cured at 110 °C for 30 minutes for the primary curing. The formed block-shaped molded article was taken out of the mold and secondarily cured in an oven at 130 °C for 2 hours to obtain a urethane resin block. After the obtained urethane resin block was allowed to cool to 25 °C, it was heated again in an oven at 120 °C for 5 hours and then subjected to slicing treatment to obtain a foamed polyurethane sheet. A double-sided tape was attached to the back surface of the obtained polyurethane sheet and used as a polishing pad.

[0054] 〔Example 2〕 To 100 parts of the same urethane prepolymer as in Example 1, 3.1 parts of unexpanded hollow fine particles with a particle size of 5 to 15 μm (average particle size: 7 μm) in which isobutane gas was encapsulated in the shell and 2 parts of 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI) were added and mixed to obtain a urethane prepolymer mixture. Further, as a curing agent, 28 parts of MOCA was heated and melted and mixed to obtain a curing agent melt. Using the urethane prepolymer mixture and the curing agent melt, a polishing pad was produced in the same manner as in Example 1.

[0055] 〔Comparative Example 1〕 As Comparative Example 1, an IC1000 pad manufactured by Nitta Haas was prepared.

[0056] 〔Comparative Example 2〕 100 parts of a urethane prepolymer with an NCO equivalent of 460, which is obtained by reacting 2,4-tolylene diisocyanate (TDI), poly(oxytetramethylene) glycol (PTMG) with a number average molecular weight of 650, poly(oxytetramethylene) glycol (PTMG) with a number average molecular weight of 1000, and diethylene glycol (DEG), is mixed with 2.1 parts of expanded hollow fine particles with a shell portion made of an acrylonitrile-vinylidene chloride copolymer and an isobutane gas encapsulated therein, and having a particle size of 30 to 50 μm (average particle size: 40 μm), to obtain a urethane prepolymer mixture. 27 parts of MOCA and 8.7 parts of polypropylene glycol are heated and melted and mixed as a curing agent, and further degassed under reduced pressure to obtain a curing agent melt. Using the urethane prepolymer mixture and the curing agent melt, a polishing pad is produced in the same manner as in Example 1.

[0057] [Comparative Example 3] To 100 parts of the urethane prepolymer of Comparative Example 2, 3.0 parts of the same hollow fine particles as those used in Example 1 are added and mixed to obtain a urethane prepolymer mixture. 25.8 parts of MOCA and 8.6 parts of polypropylene glycol are heated and melted and mixed as a curing agent, and further degassed under reduced pressure to obtain a curing agent melt. Using the urethane prepolymer mixture and the curing agent melt, a polishing pad is produced in the same manner as in Example 1.

[0058] [Comparative Example 4] To 100 parts of the urethane prepolymer of Comparative Example 2, 3.0 parts of the same hollow fine particles as those used in Example 2 are added and mixed to obtain a urethane prepolymer mixture. 25.8 parts of MOCA and 8.6 parts of polypropylene glycol are heated and melted and mixed as a curing agent, and further degassed under reduced pressure to obtain a curing agent melt. Using the urethane prepolymer mixture and the curing agent melt, a polishing pad is produced in the same manner as in Example 1.

[0059] [Dynamic Viscoelasticity Measurement] The dynamic viscoelasticity of the polyurethane sheet was measured based on the following conditions. First, the polyurethane sheet was immersed in water at a temperature of 23°C for 3 days. Using the obtained polyurethane sheet as a sample, the dynamic viscoelasticity was measured in water (immersed state). As the dynamic viscoelasticity measuring device, DMA8000 (manufactured by PerkinElmer Japan) was used. (Measurement conditions) Measuring device: DMA8000 (manufactured by PerkinElmer Japan) Sample: 4 cm in length × 0.5 cm in width × 0.125 cm in thickness Test length: 1 cm Pretreatment of sample: Kept in water at a temperature of 23°C for 3 days Test mode: Tension Frequency: 1.6 Hz (10 rad / sec) Temperature range: 20 to 100°C Temperature rising rate: 5°C / min Strain range: 0.10% Initial load: 148 g Measurement interval: 1 point / °C

[0060] Also, for reference, a polyurethane sheet in a dry state that was held in a thermo-hygrostat at a temperature of 23°C (±2°C) and a relative humidity of 50% (±5%) for 40 hours was used as a sample, and the dynamic viscoelasticity was measured in a normal atmospheric atmosphere (dry state). In addition, the measurement was performed under the same conditions as above except that RSA3 (manufactured by TA Instruments) was used as the device. The results of the dynamic viscoelasticity measurements of the examples and comparative examples are shown in FIGS. 1 to 3. Those described as (in water) in the figures are the results of the dynamic viscoelasticity measurement in the immersed state, and those described as (DRY) are the results of the dynamic viscoelasticity measurement in the dry state.

[0061] [Surface quality confirmation test] The polishing pad was installed at a predetermined position of the polishing device via a double-sided tape having an acrylic-based adhesive, and the Cu film substrate was polished under the following conditions. (Polishing conditions) Polishing machine: F-REX300 (manufactured by Ebara Corporation) Disk: A188 (manufactured by 3M) Rotation speed: (platen) 70 rpm, (top ring) 71 rpm Polishing pressure: 3.5 psi Abrasive temperature: 20 °C Abrasive discharge rate: 200 ml / min Abrasive: PLANERLITE7000 (manufactured by Fujimi Corporation) Workpiece to be polished: Cu film substrate Polishing time: 60 seconds Pad break: 35 N for 10 minutes Conditioning: Ex-situ, 35 N, 4 scans

[0062] For the 10th to 50th workpieces to be polished after the above polishing process, linear polishing scratches (scratches) larger than 155 nm on the polished surface were visually confirmed with a ReviewSEM of eDR5210 (manufactured by KLA-Tencor), and the average value was obtained. Based on the confirmation results of the scratches, the surface quality was evaluated.

[0063]

Table 1

Industrial Applicability

[0064] The polishing pad of the present invention is used for polishing optical materials, semiconductor devices, substrates for hard disks, etc., and has industrial applicability as a polishing pad particularly suitable for polishing devices in which an oxide layer, a metal layer such as copper, etc. are formed on a semiconductor wafer.

Claims

1. comprising a polyurethane sheet as the polishing layer, in the dynamic viscoelasticity measurement performed under the conditions of a frequency of 1.6 Hz and a temperature of 20 to 100°C in a water immersion state where the polyurethane sheet is immersed in water at 23°C for 3 days, the polyurethane sheet has a peak of loss tangent tanδ in the range of 41.8 to 47.8°C, the value of the peak of the loss tangent tanδ is 0.231 to 0.276, in the dynamic viscoelasticity measurement performed under the conditions of a frequency of 1.6 Hz and a temperature of 20 to 100°C in a water immersion state, the value of the loss elastic modulus E'' of the polyurethane sheet at 40°C is 22 to 33 MPa, a polishing pad.

2. in the dynamic viscoelasticity measurement performed under the conditions of a frequency of 1.6 Hz and a temperature of 20 to 100°C in a water immersion state, the difference A between the loss tangents tanδ of the polyurethane sheet at 60°C and 70°C is smaller than the difference B between the loss tangents tanδ of the polyurethane sheet at 50°C and 60°C and the difference C between the loss tangents tanδ of the polyurethane sheet at 70°C and 80°C The polishing pad according to claim 1.

3. the polyurethane sheet contains a polyurethane resin and hollow fine particles dispersed in the polyurethane resin, The polishing pad according to claim 1 or 2.

4. having a polishing step of polishing an object to be polished using the polishing pad according to any one of claims 1 to 3 in the presence of a polishing slurry, A method for manufacturing a polished product.

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