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 method for manufacturing a polishing pad and a polished workpiece. [Background technology]

[0002] Chemical mechanical polishing is performed on the surfaces (working surfaces) of materials such as semiconductor devices and electronic components, particularly thin substrates (workpieces to be polished) such as Si substrates (silicon wafers), substrates for hard disks, glass, and LCD (liquid crystal display) substrates, using a polishing pad and a polishing slurry.

[0003] As polishing pads used in such polishing processes, for example, polishing pads having a polishing layer with an E' ratio at 30°C to 90°C of approximately 1 to 3.6 are used to reduce dishing (Patent Document 1), and polishing pads having a polishing layer made of a polymer material with 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 are used to achieve both planarization performance and low defectivity (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2004-507076 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-136400 Summary of the Invention [Problem to be solved by the invention]

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

[0006] The present invention has been made in view of the above problems, and has as its object to provide a polishing pad and a method for manufacturing a polished product that can reduce the occurrence of scratches. [Means for solving the problem]

[0007] As a result of intensive research to solve the above problems, the inventors discovered that the above problems can be solved by using, as a polishing layer, a polyurethane sheet whose tan δ peak falls within a specific temperature range when dynamic viscoelasticity is measured under submerged (underwater) conditions, and thus completed the present invention.

[0008] That is, the present invention is as follows. [1] A polyurethane sheet is provided as the polishing layer, In a dynamic viscoelasticity measurement performed under conditions of a frequency of 1.6 Hz and a temperature range of 20 to 100°C while immersed in water, the polyurethane sheet has a peak of loss tangent tanδ in the range of 40 to 60°C. Polishing pad. [2] The peak value of the loss tangent tanδ is 0.15 to 0.35. The polishing pad according to [1]. [3] In a dynamic viscoelasticity measurement performed under conditions of a frequency of 1.6 Hz and a temperature of 20 to 100°C while immersed in water, the loss modulus E'' of the polyurethane sheet at 40°C is 21 MPa or more. The polishing pad according to [1] or [2]. [4] In dynamic viscoelasticity measurements performed under conditions of a frequency of 1.6 Hz and a temperature range of 20 to 100°C while submerged in water, the difference A in the loss tangent tanδ of the polyurethane sheet at 60°C and 70°C is smaller than the difference B in the loss tangent tanδ at 50°C and 60°C, and the difference C in the loss tangent 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] 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 polished workpieces. [Effects 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 that can reduce the occurrence of scratches. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing the results of dynamic viscoelasticity measurement in Example 1. [Figure 2] FIG. 10 is a diagram showing the results of dynamic viscoelasticity measurement in Example 2. [Figure 3] FIG. 1 is a diagram showing the results of dynamic viscoelasticity measurement in Comparative Example 1. [Figure 4] FIG. 10 is a diagram showing the results of dynamic viscoelasticity measurement in Comparative Example 2. [Figure 5] FIG. 10 is a diagram showing the results of dynamic viscoelasticity measurement in Comparative Example 3. [Figure 6] FIG. 10 is a diagram showing the results of dynamic viscoelasticity measurement in Comparative Example 4. DETAILED DESCRIPTION OF THE INVENTION

[0011] Below, we will explain in detail the embodiment of the present invention (hereinafter referred to as the ``present embodiment''), but the present invention is not limited to this and various modifications are possible within the scope of the gist of the present invention.

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

[0013] (loss tangent tanδ) The loss tangent tanδ is a value expressed as the ratio of the loss modulus E" (viscous component) to the storage modulus E' (elastic component), and is an index that indicates the balance between elasticity and viscosity of the material being measured under the measurement conditions. It is known that the loss tangent tanδ varies depending on whether the material being measured is dry or submerged in water, and also on the measurement frequency. In this embodiment, the dynamic viscoelasticity of the polishing layer during the dynamic process of polishing is controlled within a predetermined range, thereby improving the contact condition with the workpiece during polishing and suppressing the persistent pressing of polishing debris generated by polishing, thereby suppressing the occurrence of scratches. More specifically, by creating a state in which the loss modulus E" (viscous component) is more dominant than the storage modulus E' (elastic component) under the polishing conditions, the occurrence of scratches can be suppressed.

[0014] Under polishing conditions, the polishing layer is wet with the slurry and comes into contact with the workpiece under a predetermined polishing operation at a predetermined temperature. Therefore, in this embodiment, the polishing layer is required to have a peak loss tangent tanδ in a temperature range (40 to 60°C) equivalent to the temperature during the polishing process, when dynamic viscoelasticity is measured under conditions of a frequency of 1.6 Hz and a temperature range of 20 to 100°C while submerged in water.

[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 occurs in which the loss modulus E″ (viscous component) is more dominant than the storage modulus E′ (elastic component) in the same temperature range as the temperature in the polishing step, and the occurrence of scratches is suppressed.

[0016] Here, "having a peak in loss tangent tanδ in the range of 40 to 60°C in dynamic viscoelasticity measurement performed under conditions of 20 to 100°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, in this embodiment, "peak" refers to a temperature range of ±5°C from the temperature at which the maximum value is reached, where the difference between the maximum and minimum values ​​is 0.05 or more, and fluctuations smaller than this due to noise or the like are not considered to be peaks.

[0017] The peak value of the 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 the loss tangent tanδ is within the above range, a state in which the loss modulus E'' (viscous component) is more dominant than the storage modulus E' (elastic component) is more effectively realized in the same temperature range as the temperature in the polishing step, and the occurrence of scratches tends to be more effectively suppressed.

[0018] Furthermore, in dynamic viscoelasticity measurement performed under conditions of submerged state, frequency 1.6 Hz, and temperature 20 to 100°C, the loss 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 loss modulus E'' at 40°C is within the above range, a state in which the loss modulus E'' (viscous component) is more dominant than the storage modulus E' (elastic component) is more effectively realized in a temperature range equivalent to that of the polishing step, and the occurrence of scratches tends to be more effectively suppressed.

[0019] Furthermore, in dynamic viscoelasticity measurements performed under conditions of immersion in water at a frequency of 1.6 Hz and temperatures between 20 and 100°C, the difference A in the loss tangent tanδ of the polyurethane sheet at 60°C and 70°C is preferably smaller than the difference B in the loss tangent tanδ at 50°C and 60°C and the difference C in the loss tangent tanδ at 70°C and 80°C. That is, as shown in FIG. 1 (described later), the chart of the loss tangent tanδ preferably has a shoulder at a higher temperature than the peak. By having such a shoulder at a higher temperature, a relatively high tanδ (in water) is maintained even at a higher temperature than the peak. Therefore, a state in which the loss modulus E'' (viscous component) is more dominant than the storage modulus E' (elastic component) can be achieved over a wider temperature range. This prevents the storage modulus E' (elastic component) from becoming dominant in a locally high-temperature region during the polishing process due to frictional heat or the like, and thus tends to further suppress the occurrence of scratches.

[0020] The difference A between the loss tangent tanδ of the polyurethane sheet at 60°C and 70°C is preferably 0.010 to 0.035, more preferably 0.010 to 0.030, and even more preferably 0.012 to 0.028. The difference B between the loss tangent 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. The difference C between the loss tangent 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 difference A, which indicates the slope of the loss tangent tan δ at 60°C and 70°C, and difference B, which indicates the slope of the loss tangent tan δ at 50°C and 60°C, is preferably 0.010 to 0.040, more preferably 0.014 to 0.035, and even more preferably 0.016 to 0.030. The difference between difference A, which indicates the slope of the loss tangent tan δ at 60°C and 70°C, and difference C, which indicates the slope of the loss tangent tan δ at 70°C and 80°C, is preferably 0.030 to 0.080, more preferably 0.040 to 0.070, and even more preferably 0.050 to 0.060.

[0022] The dynamic viscoelasticity measurement in this embodiment can be performed according to a conventional method, but in the dynamic viscoelasticity measurement in a water-immersed state, a polishing layer immersed in water at a temperature of 23°C for 3 days is used as a sample, and the sample is measured while immersed in water. An example of a dynamic viscoelasticity measuring device capable of such measurements is the DMA8000 manufactured by PerkinElmer Japan. Other conditions are not particularly limited, but measurements can be performed under the conditions described in the examples.

[0023] (Polyurethane sheet) A polyurethane sheet is used as the polishing layer having the above characteristics. The polyurethane resin constituting the polyurethane sheet is not particularly limited, but examples thereof include polyester-based polyurethane resin, polyether-based polyurethane resin, and polycarbonate-based polyurethane resin. 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 a reaction product of a urethane prepolymer and a curing agent, and various known compounds can be used. The urethane prepolymer is not particularly limited, but examples include an adduct of hexamethylene diisocyanate and hexanetriol; an adduct of 2,4-tolylene diisocyanate and prenzcatechol; 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. Other isocyanate group-containing compounds prepared by the reaction of a polyisocyanate compound and a polyol compound, as well as various commercially available urethane prepolymers, may also be used. The urethane prepolymers 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 polyol compounds used in the isocyanate group-containing compound include diol compounds and triol compounds such as ethylene glycol, diethylene glycol (DEG), and butylene glycol; 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 or the reaction product of butylene glycol and adipic acid; polycarbonate polyol compounds, polycaprolactone polyol compounds, and the like. Trifunctional propylene glycols to which ethylene oxide has been added can also be used. Among these, PTMG is preferred, and a combination of PTMG and DEG is also preferred. The number-average molecular weight (Mn) of PTMG is preferably 500 to 2,000, more preferably 500 to 1,300, even more preferably 500 to 1,000, and even more preferably 500 to 800. The number-average molecular weight can be measured by gel permeation chromatography (GPC). When measuring the number average molecular weight of a polyol compound from a polyurethane resin, the number average molecular weight can be estimated by GPC after decomposing each component by a conventional method such as amine decomposition. A polyol compound may be used alone, or multiple polyol compounds may be used in combination.

[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. The "NCO equivalent" is calculated by (parts by mass of polyisocyanate compound + parts by mass of polyol compound) / [(number of functional groups per molecule of polyisocyanate compound × parts by mass of polyisocyanate compound / molecular weight of polyisocyanate compound) - (number of functional groups per molecule of polyol compound × parts by mass 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] The polyurethane sheet is preferably a foamed polyurethane sheet having cells. The cells in a foamed polyurethane sheet are classified into closed cells, in which a plurality of cells exist independently, and open cells, in which a plurality of cells are connected by interconnected holes, depending on the type of cell. Among these, the polyurethane sheet of this embodiment preferably has closed cells, and more preferably is a polyurethane sheet containing a polyurethane resin and hollow microparticles dispersed in the polyurethane resin. The use of hollow microparticles tends to facilitate adjustment of the peak temperature of the loss tangent tanδ.

[0034] A polyurethane sheet having closed cells can be formed using hollow microparticles that have an outer shell and are hollow inside. The hollow microparticles may be commercially available or synthesized by conventional methods. The material for the outer shell of the hollow microparticles is not particularly limited, but examples include polyvinyl alcohol, polyvinylpyrrolidone, poly(meth)acrylic acid, polyacrylamide, polyethylene glycol, polyhydroxyether acrylate, maleic acid copolymer, polyethylene oxide, polyurethane, poly(meth)acrylonitrile, polyvinylidene chloride, polyvinyl chloride, and organic silicone resins, as well as copolymers of two or more of the monomers that make up these resins. Commercially available hollow microparticles include, but are not limited to, the Expancel series (trade names, manufactured by Akzo Nobel) and Matsumoto Microsphere (trade name, manufactured by Matsumoto Yushi Co., Ltd.).

[0035] The shape of the hollow fine particles in the polyurethane sheet is not particularly limited and may be, for example, spherical or nearly spherical. The average particle size of the hollow fine particles is not particularly limited, but is preferably 5 to 200 μm, more preferably 5 to 80 μm, even more preferably 5 to 50 μm, and particularly preferably 5 to 35 μm. The use of such hollow fine particles also makes it possible to adjust the peak temperature of the loss tangent tanδ. The average particle size can be measured using a laser diffraction particle size distribution analyzer (for example, Mastersizer 2000, manufactured by Spectris Co., Ltd.).

[0036] The hollow fine particles are added in an amount of preferably 0.1 to 10 parts by mass, more preferably 1 to 5 parts by mass, and even more preferably 1 to 3 parts by mass, per 100 parts by mass of the urethane prepolymer.

[0037] In addition to the above components, conventionally used blowing agents may be used in combination with the hollow microparticles, provided that the effects of the present invention are not impaired. A gas unreactive with the components may be blown into the mixture during the mixing step described below. Examples of the blowing agent include water and blowing agents primarily composed of hydrocarbons having 5 or 6 carbon atoms. Examples of such hydrocarbons include linear hydrocarbons such as n-pentane and n-hexane, and alicyclic hydrocarbons such as cyclopentane and cyclohexane. In addition to the components described above, known foam stabilizers, flame retardants, colorants, plasticizers, etc. may also 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 molding process is then sliced ​​into sheets to form polyurethane sheets. By slicing, openings are formed on the surface of the sheet. To form openings on the surface of the polishing layer that are highly abrasion-resistant and less prone to clogging, the sheet may be aged at 30 to 150°C for 1 to 24 hours.

[0042] The polishing layer having the polyurethane sheet thus obtained has a double-sided tape attached to the surface opposite the polishing surface of the polishing layer, and is then cut into a predetermined shape, preferably a disk, to complete the polishing pad of this embodiment. There are no particular restrictions on the double-sided tape, and any double-sided tape known in the art can be selected and used.

[0043] The polishing pad of this embodiment may have a single-layer structure consisting of only the polishing layer, or may be a multi-layer structure in which another layer (lower layer, support layer) is attached to the surface of the polishing layer opposite the polishing surface. The properties of the other layer are not particularly limited, and if a layer softer than the polishing layer (lower A hardness or D hardness) is attached to the surface opposite the polishing layer, the polishing flatness is further improved. On the other hand, if a layer harder than the polishing layer (higher A hardness or D hardness) is attached to the surface opposite the polishing layer, the polishing rate is further improved.

[0044] In the case of a multi-layer structure, the layers may be bonded and fixed together, if necessary, under pressure, using double-sided tape, adhesive, etc. There are no particular limitations on the double-sided tape or adhesive used, and any double-sided tape or adhesive known in the art may be selected and used.

[0045] Furthermore, in the polishing pad of this embodiment, if necessary, the surface and / or back surface of the polishing layer may be subjected to a grinding process, groove processing, embossing, or hole processing (punching) on ​​the surface, a substrate and / or an adhesive layer may be attached to the polishing layer, or a light-transmitting portion may be provided. There are no particular limitations on the grinding method, and grinding can be performed by a known method. Specific examples include grinding with sandpaper. There are no particular limitations on the shape of the groove processing and embossing, and examples include lattice-type, concentric-circle-type, and radial-type shapes.

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

[0047] In this manufacturing method, while supplying the polishing slurry, the holding platen and the polishing platen are rotated relative to each other while pressing the workpiece against the polishing pad, and the workpiece surface is polished by the polishing pad using chemical mechanical polishing (CMP). The holding platen and the polishing platen may rotate in the same direction at different rotation speeds, or in different directions. Furthermore, the workpiece may be polished while moving (rotating) inside the frame during the polishing process.

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

[0049] The object to be polished is not particularly limited, but examples thereof include materials for semiconductor devices, electronic components, etc., particularly thin substrates (objects to be polished) such as Si substrates (silicon wafers), substrates for hard disks, glass, LCD (liquid crystal display) substrates, etc. Among these, the method for manufacturing a polished object of this embodiment can be suitably used as a method for manufacturing semiconductor devices having an oxide layer, a metal layer such as copper, etc. formed thereon. [Example]

[0050] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples.

[0051] Example 1 A urethane prepolymer mixture was prepared by adding 2.8 parts of expanded hollow microparticles with a particle size of 15-25 μm (average particle size: 20 μm) consisting of an acrylonitrile-vinylidene chloride copolymer shell and an isobutane gas encapsulated within it to 100 parts of a urethane prepolymer with an NCO equivalent of 460, which was prepared by reacting 2,4-tolylene diisocyanate (TDI), poly(oxytetramethylene) glycol (PTMG) with a number average molecular weight of 650, and diethylene glycol (DEG). The resulting urethane prepolymer mixture was then placed in a first liquid tank and maintained at 80°C. Separately from the first liquid tank, 25.5 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (MOCA) and 8.5 parts of polypropylene glycol were placed in a second liquid tank, melted and mixed at 120°C, and then degassed under reduced pressure to obtain a curing agent melt.

[0052] Next, the liquids in the first and second liquid tanks were poured into a mixer equipped with two injection ports, and mixed under stirring to obtain a mixed liquid. The mixing ratio was adjusted so that the R value, which represents the equivalent ratio of the amino and hydroxyl groups in the curing agent to the terminal isocyanate groups in the urethane prepolymer, was 0.90.

[0053] The resulting mixture was poured into a mold preheated to 100°C and subjected to primary curing at 110°C for 30 minutes. The resulting block-shaped molding was removed from the mold and subjected to secondary curing in an oven at 130°C for 2 hours to obtain a urethane resin block. The resulting urethane resin block was allowed to cool to 25°C, then heated again in an oven at 120°C for 5 hours, and then sliced ​​to obtain a foamed polyurethane sheet. Double-sided tape was attached to the back of the resulting polyurethane sheet, which was then used as a polishing pad.

[0054] Example 2 100 parts of the same urethane prepolymer as in Example 1 were mixed with 3.1 parts of unexpanded hollow particles with a particle size of 5 to 15 μm (average particle size: 7 μm) containing isobutane gas in the shell, and 2 parts of 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI) to obtain a urethane prepolymer mixture. 28 parts of MOCA were heated and melted and mixed as a curing agent to obtain a curing agent melt. A polishing pad was produced using the urethane prepolymer mixture and the curing agent melt 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 A urethane prepolymer mixture was prepared by mixing 100 parts of a urethane prepolymer with an NCO equivalent of 460, which was prepared 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). 2.1 parts of expanded hollow microparticles with a shell of acrylonitrile-vinylidene chloride copolymer and a particle size of 30-50 μm (average particle size: 40 μm), each containing isobutane gas, were added and mixed to obtain a urethane prepolymer mixture. 27 parts of MOCA and 8.7 parts of polypropylene glycol were heated, melted, and mixed as a curing agent, followed by degassing under reduced pressure to obtain a curing agent melt. A polishing pad was prepared using the urethane prepolymer mixture and curing agent melt in the same manner as in Example 1.

[0057] Comparative Example 3 100 parts of the urethane prepolymer of Comparative Example 2 was mixed with 3.0 parts of the same hollow particles as those used in Example 1 to obtain a urethane prepolymer mixture. 25.8 parts of MOCA and 8.6 parts of polypropylene glycol were heated, melted, and mixed as a curing agent, and then degassed under reduced pressure to obtain a curing agent melt. A polishing pad was prepared using the urethane prepolymer mixture and the curing agent melt in the same manner as in Example 1.

[0058] Comparative Example 4 100 parts of the urethane prepolymer of Comparative Example 2 was mixed with 3.0 parts of the same hollow particles as those used in Example 2 to obtain a urethane prepolymer mixture. 25.8 parts of MOCA and 8.6 parts of polypropylene glycol were heated, melted, and mixed as a curing agent, and then degassed under reduced pressure to obtain a curing agent melt. A polishing pad was prepared using the urethane prepolymer mixture and the curing agent melt in the same manner as in Example 1.

[0059] [Dynamic viscoelasticity measurement] Dynamic viscoelasticity measurements were performed on the polyurethane sheets under the following conditions. First, the polyurethane sheets were immersed in water at 23°C for 3 days. The resulting polyurethane sheets were used as samples and subjected to dynamic viscoelasticity measurements in water (submerged state). A DMA8000 (manufactured by PerkinElmer Japan) was used as the dynamic viscoelasticity measuring device. (Measurement conditions) Measuring device: DMA8000 (PerkinElmer Japan) Sample: 4cm long x 0.5cm wide x 0.125cm thick Test length: 1cm Sample pretreatment: Keep in water at 23°C for 3 days Test mode: Tensile Frequency: 1.6Hz (10rad / sec) Temperature range: 20~100℃ Heating rate: 5℃ / min Distortion range: 0.10% Initial load: 148g Measurement interval: 1point / ℃

[0060] For reference, a polyurethane sheet in a dry state was kept in a thermo-hygrostat at a temperature of 23°C (±2°C) and a relative humidity of 50% (±5%) for 40 hours, and a sample was used to perform dynamic viscoelasticity measurements in normal air (dry state). The measurements were performed under the same conditions as above, except that an RSA3 (manufactured by TA Instruments) was used. The results of the dynamic viscoelasticity measurements for the examples and comparative examples are shown in Figures 1 to 3. In the figures, the results marked "(in water)" are the results of the dynamic viscoelasticity measurements in a water-immersed state, and the results marked "(DRY)" are the results of the dynamic viscoelasticity measurements in a dry state.

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

[0062] After the above polishing process, the polished surfaces of the 10th to 50th pieces were visually inspected for linear scratches larger than 155 nm using a ReviewSEM eDR5210 (manufactured by KLA-Tencor Corporation), and the average value was calculated. Surface quality was evaluated based on the results of the scratch inspection.

[0063] [Table 1] [Industrial Applicability]

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

Claims

1. A polyurethane sheet is provided as the polishing layer, A polyurethane sheet is immersed in water at a temperature of 23°C for 3 days, and in a dynamic viscoelasticity measurement conducted under conditions of a frequency of 1.6 Hz and a temperature of 20 to 100°C in the submerged state, the polyurethane sheet has a peak of loss tangent tanδ in the range of 40 to 60°C, a difference A between the loss tangent tanδ at 60°C and 70°C of the polyurethane sheet is smaller than a difference B between the loss tangent tanδ at 50°C and 60°C and a difference C between the loss tangent tanδ at 70°C and 80°C; Polishing pad.

2. A difference between a difference A indicating the slope of the loss tangent tanδ at 60°C and 70°C and a difference B indicating the slope of the loss tangent tanδ at 50°C and 60°C is 0.010 to 0.040, a 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 being 0.030 to 0.080; The polishing pad of claim 1 .

3. The peak value of the loss tangent tanδ is 0.15 to 0.

35. The polishing pad according to claim 1 or 2.

4. In a dynamic viscoelasticity measurement performed under conditions of a frequency of 1.6 Hz and a temperature of 20 to 100°C while immersed in water, the polyurethane sheet has a loss modulus E'' of 21 MPa or more at 40°C. The polishing pad according to any one of claims 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 claims 1 to 4.

6. A polishing step of polishing an object to be polished using the polishing pad according to any one of claims 1 to 5 in the presence of a polishing slurry. A method for manufacturing polished workpieces.

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