Polishing pad

Abstract

To provide a polishing pad including an end point detection window which suppresses deterioration caused by light and can enhance end point detection accuracy.SOLUTION: A polishing pad 3 includes a polishing layer having an end point detection window 5 formed on a part of the polishing layer. A difference of yellowness before and after light resistance testing of the end point detection window 5 is 20.00 or less, and a ratio of tensile strength after the light resistance testing to the tensile strength before the light resistance testing is 0.85 or higher. A ratio of chromaticity of yellow after the light resistance testing to the chromaticity of yellow before the light resistance testing of the end point detection window 5 is 2.0 or less.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a polishing pad. Specifically, the present invention relates to a polishing pad that can be suitably used for polishing optical materials, semiconductor wafers, semiconductor devices, substrates for hard disks, and the like.

Background Art

[0002] As a polishing method for planarizing the surfaces of optical materials, semiconductor wafers, semiconductor devices, and substrates for hard disks, a chemical mechanical polishing (CMP) method is generally used.

[0003] The CMP method will be described with reference to FIG. 1. As shown in FIG. 1, a polishing apparatus 1 for carrying out the CMP method is provided with a polishing pad 3, and the polishing pad 3 is in contact with a workpiece 8 held on a holding platen 16, and includes a polishing layer 4 which is a layer for polishing and a cushion layer 6 for supporting the polishing layer 4. The polishing pad 3 is rotationally driven with the workpiece 8 being pressed, and polishes the workpiece 8. At this time, a slurry 9 is supplied between the polishing pad 3 and the workpiece 8. The slurry 9 is a mixture (dispersion) of water and various chemical components and hard fine abrasive grains, and the chemical components and abrasive grains in it increase the polishing effect by relative movement with the workpiece 8 while flowing. The slurry 9 is supplied to and discharged from the polishing surface through grooves or holes.

[0004] In the CMP method, there is a method of optically confirming whether the workpiece 8 has been polished to a desired position. For example, the polishing apparatus 1 shown in FIG. 1 includes an optical sensor 14 or the like for confirming the end point. Specifically, an end point detection window 5 having translucency is provided in a part of the polishing pad 3, and further, a light source 13 and an optical sensor 14 are provided under the polishing platen 10.

[0005] The principle of endpoint detection by an optical method will be described with reference to Fig. 2. When the light 2 irradiated by the light source 13 is incident on the thin film (e.g., insulating film) 12 formed on the substrate 11 which is the object to be polished 8, a part of the light 2a is reflected from the surface of the thin film 12, while another part of the light 2b passes through the thin film 12 and is reflected from the surface of the object to be polished 8. The reflected lights 2a and 2b are detected by the optical sensor 14 through the endpoint detection window 5. Depending on the thickness of the thin film 12, a phase difference and intensity variations of the reflected light occur, and by detecting the phase difference and the reflected intensity change, the polishing status of the thin film 12 can be confirmed.

[0006] Here, the endpoint detection window 5 may be made of the same material as the polishing layer 4, and for example, it is made of a light-transmissive polyurethane. However, it is known that polyurethane deteriorates by ultraviolet light, and the endpoint detection window 5 deteriorates due to the irradiated light for endpoint detection. Therefore, various additives have been conventionally used to suppress the deterioration of the endpoint detection window 5.

[0007] For example, Patent Document 1 discloses a polishing pad having an endpoint detection window containing at least one of an ultraviolet absorber and a hindered amine light stabilizer.

[0008] Also, Patent Document 2 discloses a polishing pad having an endpoint detection window containing a light-absorbing compound such as cyanoacrylate.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0010] However, although the polishing pads described in Patent Documents 1 and 2 suppress the deterioration of the end point detection window to a certain extent, the end point detection window may turn yellow. When the end point detection window turns yellow, the light transmittance of the end point detection window fluctuates, which may affect the detection accuracy of the polishing state (polishing end point). In addition, the change (deterioration) in physical properties affects the scratch performance, so it is preferable to further suppress the deterioration of the end point detection window.

[0011] The present invention has been made in view of the above problems, and an object thereof is to provide a polishing pad capable of improving the detection accuracy of the polishing state (polishing end point) while suppressing changes in physical properties.

Means for Solving the Problems

[0012] As a result of intensive research, the present inventor has found that by including a specific antioxidant in the end point detection window, changes (deterioration) and yellowing of physical properties are suppressed, the scratch performance and polishing detection accuracy are less affected, and an end point detection window capable of accurately detecting the polishing state (polishing end point) is obtained. That is, the present invention includes the following. [1] A polishing pad having a polishing layer provided with an end point detection window in part, wherein the difference in yellow chromaticity before and after the light resistance test of the end point detection window is 20.00 or less, The ratio of the tensile strength after the light resistance test to the tensile strength before the light resistance test is 0.85 or more, Polishing pad. [2] The polishing pad according to [1], wherein the ratio of the yellow chromaticity after the light resistance test to the yellow chromaticity before the light resistance test of the end point detection window is 2.0 or less. [3] The polishing pad according to [1] or [2], wherein the yellow chromaticity of the end point detection window before the light resistance test is 0 to 30.00. [4] The polishing pad according to any one of [1] to [3], wherein the color difference before and after the light resistance test of the end point detection window is 25.0 or less.

Effects of the Invention

[0013] The polishing pad provided with the end point detection window of the present invention has little adverse effect on the detection accuracy of the polishing state (polishing end point) due to yellowing, and can detect the accurate polishing state (polishing end point). In addition, the end point detection window has little deterioration due to light and can reduce the influence on scratches.

Brief Description of Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments for carrying out the invention will be described, but the present invention is not limited to the embodiments for carrying out the invention.

[0016] <<Polishing Pad>> The structure of the polishing pad 3 will be described with reference to FIG. 3. The polishing pad 3 provided in the polishing apparatus 1 includes a polishing layer 4 having at least one end point detection window 5 (two end point detection windows 5 in FIG. 3) penetrating the polishing pad 3, and a cushion layer 6. Since the polishing pad 3 has the end point detection window 5, the polishing state of the workpiece 8 can be optically confirmed using the light source 13 and the optical sensor 14. The shape of the polishing pad 3 is preferably a disk shape, but is not particularly limited, and the size (diameter) can also be appropriately determined according to the size of the polishing apparatus 1 provided with the polishing pad 3, etc. For example, it can be about 10 cm to 1 m in diameter. Note that for the polishing pad 3 of the present invention, it is preferable that the polishing layer 4 is adhered to the cushion layer 6 via the adhesive layer 7, but it may also be composed of only the polishing layer 4. The polishing pad 3 is attached to the polishing surface plate 10 of the polishing apparatus by means such as double-sided tape disposed on the cushion layer 6. The polishing pad 3 is rotationally driven while pressing the workpiece 8 by the polishing apparatus, and polishes the workpiece.

[0017] <Polishing layer> The polishing pad 3 includes a polishing layer 4 which is a layer for polishing the workpiece. As the material constituting the polishing layer 4, polyurethane resin, polyurea resin, and polyurethane polyurea resin can be preferably used, and more preferably polyurethane resin can be used. The size (diameter) of the polishing layer 4 is the same as that of the polishing pad 3, and can be about 10 cm to 2 m in diameter. The thickness of the polishing layer 4 can usually be about 0.5 to 5 mm. The polishing layer 4 is rotated together with the polishing surface plate 10 of the polishing apparatus 1, and while flowing the slurry 9 thereon, the chemical components and abrasive grains contained in the slurry are relatively moved together with the workpiece 8, thereby polishing the workpiece 8. By performing groove processing such as concentric, lattice, and radial shapes on the surface of the polishing layer 4, the retention and discharge of the slurry 9 can be adjusted, and the polishing characteristics can be changed. Further, if necessary, the polishing layer 4 can include a hollow body such as hollow microspheres.

[0018] <Endpoint detection window> The polishing layer 4 has at least one endpoint detection window 5. Since the endpoint detection window 5 is for confirming the endpoint of polishing by optical means, it has translucency. Therefore, it is preferable that the endpoint detection window 5 has higher translucency. The number of the endpoint detection windows 5 is usually one or more. The diameter of the endpoint detection window 5 is preferably about 1 cm to 15 cm, and the thickness is the same as that of the polishing layer 4, usually about 0.5 to 5 mm. Details of the endpoint detection window 5 will be described in the section of <<Manufacturing method of endpoint detection window>>.

[0019] The end point detection window 5 generally has a columnar shape that penetrates the upper and lower surfaces of the polishing layer 4. However, it is not particularly limited as long as it penetrates the upper and lower surfaces of the polishing layer 4, and a square prism shape, a triangular prism shape, etc. can be appropriately selected.

[0020] (Light transmittance) In order for the end point detection window 5 to transmit light, it is preferable that the light transmittance is high at wavelengths of 300 to 800 nm, which are frequently used. For example, the transmittance of light at 660 nm is preferably 50% or more, more preferably 60% or more, still more preferably 70% or more, and even more preferably 80% or more. In particular, if the light transmittance is high at wavelengths of 400 to 700 nm, errors are less likely to occur and measurement can be performed with high accuracy. The transmittance can be measured using a spectrophotometer (U-3210 Spectro Photometer, manufactured by Hitachi, Ltd.), and the sample thickness at this time is, for example, 1.3 mm.

[0021] (Chromaticity (b*) and yellowness degree (Δb*)) As characteristics of the end point detection window 5 in the present invention, it can be mentioned that the chromaticity b* of yellow is low and the yellowness degree is not easily reduced (the yellowness degree is small) even when used. In particular, having a specific yellowness degree is one of the important characteristics of the present invention. Here, the chromaticity of yellow refers to the chromaticity b* expressed in the L*a*b* color space, and the larger the numerical value of the chromaticity b*, the stronger the degree of yellow. Also, generally, the main component of the end point detection window 5 is preferably the same component as the polishing layer 4. That is, the main components of the material of the end point detection window 8 are often polyurethane resin, polyurea resin, and polyurethane-polyurea resin, but there is a problem that it turns yellow over time. The end point detection window 5 of the polishing pad 1 of the present invention has a low chromaticity b* of yellow and a small yellowness degree even when used. The chromaticity of yellow (b*1) expressed in the L*a*b* color space using a color difference meter immediately after the manufacture of the end point detection window 5 is preferably 25 or less, more preferably 20 or less, still more preferably 15 or less. The difference (Δb*) between the chromaticity (b*1) measured using a color difference meter before the light resistance test of the end point detection window 5 (performed using an F-type apparatus in accordance with JIS B 7751) and the chromaticity (b*2) measured using a color difference meter after the light resistance test is preferably 20 or less, more preferably 15 or less, and still more preferably 13 or less. In the L*a*b* color space, in addition to b* indicating the chromaticity of yellow or blue, there are L* indicating lightness and a* indicating the chromaticity of red or green. The color difference ΔE* can be obtained from the differences in lightness L*, chromaticity a*, and b* before and after the light resistance test. ΔE* = [(L*2 - L*1) 2 +(a*2 - a*1) 2 +(b*2 - b*1) 2 1 / 2 Here, let the lightness before the light resistance test be L*1, the chromaticity be a*1, and b*1, and the lightness L*2, the chromaticity be a*2, and b*2 after the light resistance test. The color difference ΔE* is preferably 25 or less, more preferably 20 or less, and still more preferably 17 or less.

[0022] (Tensile strength) In addition, as a characteristic of the end point detection window 5 in the present invention, it is possible to suppress deterioration due to light, and particularly, the change in tensile strength is small. The light irradiated from the light source during end point detection deteriorates the end point detection window 5. Since the deterioration of the end point detection window 5 affects the polishing performance and scratch performance of the polishing pad 3, it is preferable that the physical properties of the end point detection window 5 are maintained even when irradiated with light. Among the physical properties, particularly the tensile strength greatly affects the scratch performance, so it is preferable that the change in tensile strength is small. The end point detection window 5 of the polishing pad 1 of the present invention has a ratio of the tensile strength after the light resistance test to the tensile strength before the light resistance test within a specific range. The ratio of the tensile strength after the light resistance test to the tensile strength before the light resistance test of the end point detection window 5 is preferably 0.85 to 1.00, more preferably 0.87 to 1.00, and still more preferably 0.90 to 1.00.

[0023] <Cushion layer> ​The cushion layer 6 is preferably composed of an impregnated nonwoven fabric impregnated with resin, a flexible material such as synthetic resin, a foam having a bubble structure, etc. With such a material, the contact of the polishing layer 4 with the workpiece 8 can be made more uniform. In the present invention, the polishing pad 3 may be composed of only the polishing layer 4, but it is preferably adhered to the cushion layer 6. Also, in the cushion layer 6, it is necessary to form the same number of holes as the end point detection window 5 in the portion corresponding to the installation position of the end point detection window 5 so that light for performing light detection can pass through.

[0024] <Adhesive layer> The adhesive layer 7 is a layer for adhering the cushion layer 6 and the polishing layer 4, and is usually composed of a double-sided tape or an adhesive. A double-sided tape or an adhesive known in the art can be used. The polishing pad 3 and the cushion layer 6 are bonded together by the adhesive layer 7. The adhesive layer 7 can be formed of at least one adhesive selected from, for example, acrylic, epoxy, and urethane adhesives. For example, an acrylic adhesive is used and the thickness can be set to 0.1 mm.

[0025] <Polishing device> As already described, the polishing device 1 provided with the polishing pad 3 of the present invention can confirm the polishing state by optical means. For example, as shown in FIG. 1, the polishing surface plate 10 of the polishing device 1 includes a light source 13 and an optical sensor 14. The light emitted from the light source 13 passes from below to above the polishing surface plate 10, further passes through the holes of the cushion layer 6, and further through the end point detection window 5 of the polishing pad 3 to reach the workpiece 8, and the optical sensor 14 senses the light reflected back from the workpiece 8. In this way, the light source 13 and the optical sensor 14 can rotate together with the polishing surface plate 10 to confirm the polishing situation while polishing.

[0026] <<Manufacturing method of end point detection window>> The manufacturing method of the end point detection window of the present invention will be described.

[0027] <Material of the endpoint detection window> The endpoint detection window 5 measures the film thickness by transmitting light and measuring the wavelength of the light reflected by the substrate. However, since it may also be required to function in the same way as the polishing layer 4, that is, to polish the workpiece 8, it is preferable that the scratch performance and polishing performance are equivalent, and the main component is preferably the same component as the polishing layer 4. That is, the main component of the material of the endpoint detection window 8 is preferably a polyurethane resin, a polyurea resin, or a polyurethane-polyurea resin, and more preferably a polyurethane resin. Specific examples of the material of the main component include, for example, a material obtained by reacting a urethane bond-containing polyisocyanate compound with a curing agent.

[0028] The endpoint detection window 5 provided in the polishing pad 3 of the present invention contains a phenolic antioxidant and a phosphorus-based antioxidant as antioxidants. By combining the phenolic antioxidant and the phosphorus-based antioxidant, it is possible to manufacture the endpoint detection window 5 with a high light transmittance that could not be achieved by the phenolic antioxidant alone or the phosphorus-based antioxidant alone. Moreover, the endpoint detection window 5 containing the phenolic antioxidant and the phosphorus-based antioxidant is less likely to deteriorate due to oxidation, change in physical properties (especially a decrease in tensile strength), and yellowing. Specific components will be described later.

[0029] Hereinafter, the manufacturing method of the material of the endpoint detection window 5 will be described by taking the endpoint detection window using a urethane bond-containing isocyanate compound, a polyol compound, and a curing agent as an example.

[0030] Examples of the manufacturing method of the endpoint detection window 5 using a urethane bond-containing polyisocyanate compound and a curing agent include, for example, a material preparation step of preparing at least a urethane bond-containing polyisocyanate compound, an antioxidant, an additive, and a curing agent; a mixing step of mixing at least the urethane bond-containing polyisocyanate compound, the antioxidant, the additive, and the curing agent to obtain a mixed solution for forming a molded body; and a curing step of forming an endpoint detection window from the mixed solution for forming the molded body.

[0031] Hereinafter, it will be described separately for the material preparation process, the mixing process, and the forming process.

[0032] <Material preparation process> For the production of the end point detection window 5 of the present invention, at least a urethane bond-containing polyisocyanate compound (urethane prepolymer), a curing agent, and an antioxidant are prepared as raw materials for the polyurethane resin molded body (cured resin). Here, the urethane bond-containing polyisocyanate is a urethane prepolymer for forming the polyurethane resin molded body. When the end point detection window 5 is made of a polyurea resin molded body or a polyurethane-polyurea resin molded body, a prepolymer corresponding thereto is used.

[0033] Hereinafter, each component will be described.

[0034] (Urethane bond-containing polyisocyanate compound) The urethane bond-containing polyisocyanate compound (urethane prepolymer) is a compound obtained by reacting the following polyisocyanate compound and polyol compound under usually used conditions, and contains a urethane bond and an isocyanate group in the molecule. Also, within a range that does not impair the effects of the present invention, other components may be contained in the urethane bond-containing polyisocyanate compound.

[0035] As the urethane bond-containing polyisocyanate compound, a commercially available one may be used, or one synthesized by reacting a polyisocyanate compound and a polyol compound may be used. There are no particular restrictions on the reaction, and an addition polymerization reaction may be carried out using known methods and conditions in the production of polyurethane resins. For example, it can be produced by a method such as adding a polyisocyanate compound heated to 50°C to a polyol compound heated to 40°C while stirring in a nitrogen atmosphere, raising the temperature to 80°C after 30 minutes, and further reacting at 80°C for 60 minutes.

[0036] The NCO equivalent of the urethane bond-containing polyisocyanate compound (urethane prepolymer) obtained as described above is preferably 200 or more and 700 or less, more preferably 250 or more and 600 or less, and still more preferably 300 or more and 550 or less. By the NCO equivalent being within the above range, it can be more suitably adjusted according to the desired physical property range.

[0037] Further, the NCO equivalent is a numerical value indicating the molecular weight of the prepolymer (PP) per NCO group, which 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)]”.

[0038] (Polyisocyanate compound) In the present specification, the polyisocyanate compound means a compound having two or more isocyanate groups in the molecule. The polyisocyanate compound is not particularly limited as long as it has two or more isocyanate groups in the molecule. For example, as the diisocyanate compound having two isocyanate groups in the molecule, 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 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, ethylidine diisothiocyanate, etc. can be mentioned. These polyisocyanate compounds may be used alone or in combination of a plurality of polyisocyanate compounds.

[0039] 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 preferably composed only 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.

[0040] (Polyol compound as a raw material of the prepolymer) In this specification, the polyol compound means a compound having two or more hydroxyl groups (OH) in the molecule. Examples of the polyol compound used for synthesizing the urethane bond-containing polyisocyanate compound as a prepolymer include diol compounds such as ethylene glycol, diethylene glycol (DEG), and butylene glycol, triol compounds, etc.; polyether polyol compounds such as poly(oxytetramethylene) glycol (or polytetramethylene ether glycol) (PTMG). Among these, PTMG is preferred. The number average molecular weight (Mn) of PTMG is preferably from 500 to 2000, more preferably from 600 to 1300, and even more preferably from 650 to 1000. The number average molecular weight can be measured by gel permeation chromatography (GPC). 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 above polyol compound may be used alone or in combination of a plurality of polyol compounds.

[0041] (Antioxidant) As the material of the end point detection window 5, an antioxidant is included if necessary. The antioxidant is not particularly limited, and examples thereof include phenolic antioxidants, amine antioxidants, benzimidazole antioxidants, and phosphorus antioxidants. Among these, from the viewpoint of low yellowness degree, a phenolic antioxidant or a phosphorus antioxidant is preferred, and it is more preferred to coexist a phenolic antioxidant and a phosphorus antioxidant. The total content of the antioxidant in the end point detection window 5 is preferably from 0.1 to 6.0% by weight, more preferably from 0.2 to 4.0% by weight based on the weight of the entire end point detection window.

[0042] Polyurethane, which is a typical main component of the end point detection window 5, is considered to generate radicals by light and produce colored substances. The radical reaction becomes a cycle reaction as shown in the following formula (1), and yellowing progresses (wherein R represents an organic group). However, by the presence of a phenolic antioxidant, peroxy radicals are scavenged, and by further the presence of a phosphorus antioxidant, it is considered that they become stable compounds and the cycle reaction can be blocked. In addition to the progress of yellowing, it is possible to maintain the physical properties of the end point detection window 5, particularly to suppress a decrease in the tensile strength. By suppressing the decrease in the tensile strength of the end point detection window 5, it is possible to maintain the same level of performance as the polishing layer 4 with respect to polishing performance and scratch performance.

[0043]

Chemical formula

[0044] (Mixing ratio) One or more kinds of antioxidants can be used, but from the viewpoint of reducing the degree of yellowing, it is preferable to use both a phenolic antioxidant and a phosphorus antioxidant. At this time, the weight mixing ratio of the phenolic antioxidant and the phosphorus antioxidant (phenolic antioxidant: phosphorus antioxidant) is not particularly limited, but from the viewpoint of the degree of yellowing, it is preferably 1:0.1 to 1:10, and more preferably 1:0.2 to 1:8. When a polyurethane resin, a polyurea resin, and a polyurethane-polyurea resin are used as the main components of the end point detection window 5, the above ratio shows a further effect.

[0045] The method of mixing these antioxidants is not particularly limited, but if the phenolic antioxidant is mixed with the prepolymer at an initial stage, the reaction may proceed. Therefore, the phenolic antioxidant is preferably added when the curing agent and the prepolymer are mixed. For example, by mixing the phenolic antioxidant with the curing agent and then mixing the mixture of the curing agent and the phenolic antioxidant with the prepolymer, curing can proceed. On the other hand, unlike the phenolic antioxidant, the phosphorus antioxidant may be premixed with the prepolymer before the curing reaction, or may be mixed with the prepolymer after being mixed with the curing agent together with the phenolic antioxidant.

[0046] Although the molecular weight of the phenolic antioxidant is not particularly limited, from the viewpoint of compatibility with polyurethane and the like, the number average molecular weight is preferably 300 to 1000, more preferably 400 to 700. Regarding the molecular weight of the phosphorus-based antioxidant, although it is not particularly limited, from the viewpoint of compatibility with polyurethane and the like, the number average molecular weight is preferably 300 to 800, more preferably 300 to 500.

[0047] Specific examples of phenolic antioxidants include 6-di-tert-butyl-p-cresol, 2,6-diphenyl-4-octadecyloxyphenol, stearyl (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, distearyl (3,5-di-tert-butyl-4-hydroxybenzyl) phosphonate, tridecyl 3,5-di-tert-butyl-4-hydroxybenzylthioacetate, bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylene bis(oxyethylene)], thiodiethylene bis[(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 4,4'-thiobis(6-tert-butyl-m-cresol), 2-octylthio-4,6-bis(3,5-di-tert-butyl-4-hydroxyphenoxy)-s-triazine, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), bis[3,3-bis(4-hydroxy-3-tert-butylphenyl)butyric acid] glycol ester, 4,4'-butylidenebis(6-tert-butyl-3-methylphenol), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane, bis[2-tert-butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl] terephthalate, 1,3,5-tris(2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene, 1,3,5-tris[(3,5-di-tert-butyl-4-hydroxyphenyl)propionyloxyethyl] isocyanurate, tetrakis[methylene-3-(3',5'-Di-tert-butyl-4'-hydroxyphenyl)propionate]methane, 2-tert-butyl-4-methyl-6-(2-acryloyloxy-3-tert-butyl-5-methylbenzyl)phenol, triethylene glycol bis[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate], octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3,9-bis{2-[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,0-tetraoxaspiro[5.5]undecane, 4,4-butylidenebis(6-tert-butyl-3-methylphenol), and the like can be mentioned.,

[0048] Among the above phenolic antioxidants, from the viewpoint of improving the transmittance of the end point detection window 5 and being less likely to yellow, preferred examples include Irganox 245, Adeka Stab AO-50 / Adeka Stab AO-50F (trademark), Adeka Stab AO-60 / Adeka Stab AO-60G (trademark), Adeka Stab AO-80 (trademark) (the above are manufactured by ADEKA CORPORATION); Sumilizer BBM-S (trademark), Sumilizer GA-80 (trademark), Sumilizer BHT (trademark), Sumilizer BP-76 (trademark), Sumilizer BP-101 (trademark) (the above are manufactured by Sumitomo Chemical Co., Ltd.), and the like can be mentioned.,

[0049] Specific examples of phosphorus-based antioxidants include triphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(2,5-di-tert-butylphenyl) phosphite, tris(nonylphenyl) phosphite, tris(dinonylphenyl) phosphite, tris(mono, di mixed nonylphenyl) phosphite, diphenyl acid phosphite, 2,2'-methylenebis(4,6-di-tert-butylphenyl) octyl phosphite, diphenyl decyl phosphite, diphenyl octyl phosphite, bis(nonylphenyl) pentaerythritol phosphite, phenyl diisodecyl phosphite, tributyl phosphite, tris(2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, dibutyl acid phosphite, dilauryl acid phosphite, trilauryl trithiophosphite, bis(neopentyl glycol)·1,4-cyclohexanedimethyl diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis{2,4-bis(1-methyl-1-phenylethyl)phenyl} pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, tetra(C12-15 mixed alkyl)-4,4-isopropylidenediphenyl phosphite, bis[2,2'-methylenebis(4,6-diamylphenyl)]·isopropylidenediphenyl phosphite, tetratridecyl·4,4'-butylidenebis(2-tert-butyl-5-methylphenol) diphosphite, hexa(tridecyl)·1,1,3-tris(2-methyl-5-tert-butyl-4-hydroxyphenyl) butane·triphosphite, tetrakis(2,4-di-tert-butylphenyl) biphenylene diphosphonite, tris(2-[(2,4,8,10-tetrakis-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)oxy]ethyl)amine, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 2-butyl-2-ethylpropanediol·2,4,Examples include 6-tri-tert-butylphenol monophosphite and the like.,

[0050] Among the above phosphorus-based antioxidants, phosphite compounds that are suitable from the viewpoint of being less likely to turn yellow are triphenyl phosphite, distearyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, and bis{2,4-bis(1-methyl-1-phenylethyl)phenyl}pentaerythritol diphosphite.,

[0051] Specific examples include Adeka Stab PEP-8 (trademark), Adeka Stab PEP-24G (trademark), Adeka Stab PEP-45 (trademark), Adeka Stab TPP (all manufactured by ADEKA CORPORATION); JPP681S (trademark, manufactured by Johoku Chemical Industry Co., Ltd.), Alkanox P-24 (trademark, manufactured by Great Lakes), Ultranox P626 (trademark, manufactured by GE Specialty Chemicals), Doverphos S-9432 (trademark), Doverphos S-9228 (trademark) (all manufactured by Dover Chemical); Irgaofos 126 and 126FF (trademark, manufactured by CIBA SPECIALTY CHEMICALS).

[0052] Among the above antioxidants, bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylene bis(oxyethylene)] and stearyl (3,5-di-tert-butyl-4-hydroxyphenyl)propionate as phenolic antioxidants, and triphenyl phosphite and tridecyl phosphite as phosphorus-based antioxidants are particularly preferred.,

[0053] (Hardener) In the method for manufacturing the end point detection window 5 of the present invention, in the mixing step, a curing agent (also referred to as a chain extender) is mixed with a urethane bond-containing polyisocyanate compound or the like. By adding the curing agent, in the subsequent molded body molding step, the main chain terminal of the urethane bond-containing polyisocyanate compound binds to the curing agent to form a polymer chain and hardens. Examples of the hardening agent include polyvalent amine compounds such as 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-(isopropylamino)-4-hydroxyphenyl]propane, 2,2-bis[3-(1-methylpropylamino)-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, trimethylethylenebis-4-aminobenzoate, and polytetramethylene oxide-di-p-aminobenzoate; and polyhydric alcohol compounds such as ethylene glycol, 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.In addition, the polyamine compound may have a hydroxyl group. Examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylenediamine, di-2-hydroxypropylenediamine, and the like. As the polyamine compound, a diamine compound is preferable, and it is more preferable to use, for example, 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (hereinafter abbreviated as MOCA). The total content of the curing agent in the end point detection window 5 is preferably 10 to 50% by weight, more preferably 15 to 40% by weight, based on the weight of the entire end point detection window.

[0054] (Additive) As the material of the end point detection window 5, an additive can be optionally added so as not to lose transparency.

[0055] <Mixing step> In the mixing step, the urethane bond-containing polyisocyanate compound (urethane prepolymer), additive, and curing agent obtained in the preparation step are supplied into a mixer and stirred and mixed. The mixing step is carried out in a state where the temperature is raised to a temperature at which the fluidity of each of the above components can be ensured. In the mixing process, at least a urethane bond-containing polyisocyanate compound (urethane prepolymer), a phenolic antioxidant, a phosphorus-based antioxidant, and a curing agent are supplied into a mixer and stirred and mixed. For the phenolic antioxidant and the phosphorus-based antioxidant, as described above, they are added and mixed so that no reaction occurs before mixing. In this way, a mixed liquid for forming a molded body is prepared. The mixing process is carried out in a state of being heated to a temperature at which the fluidity of each of the above components can be ensured. It is possible to use the R value, which is the equivalent ratio of the active hydrogen groups (amino group and hydroxyl group) present in the curing agent to the isocyanate groups present at the terminals of the urethane bond-containing polyisocyanate compound as the urethane prepolymer, as an index. The R value is preferably 0.70 to 1.30, more preferably 0.75 to 1.20, still more preferably 0.80 to 1.10, even more preferably 0.80 to 1.00, and even more preferably 0.85 to 0.95.

[0056] <Forming Process> In the molded body forming process, the mixed liquid for forming a molded body prepared in the above mixing process is poured into a rod-shaped mold preheated to 30 to 100 °C and first cured, and then heated at about 100 to 150 °C for about 10 minutes to 5 hours to be secondarily cured, thereby forming a cured polyurethane resin (polyurethane resin molded body). At this time, the urethane prepolymer and the curing agent react to form a polyurethane resin, whereby the mixed liquid is cured. Note that the mold is provided with unevenness or a thread-cutting structure, so that it is possible to prevent the end point detection window 5 from coming off from the polished layer 4 in which it is formed.

[0057] If the end point detection window 5 contains bubbles, the light from the light source 13 is reflected by the bubbles, resulting in a decrease in the light transmittance, which may affect the accuracy of end point detection. Therefore, in order to prevent the end point detection window 5 from containing bubbles, for example, sufficient vacuum degassing can be performed at the stage of preparing the material.

[0058] <<Manufacturing Method of the Polished Layer>> A method for manufacturing the polishing layer 4 of the present invention will be described. The material of the polishing layer 4 is not particularly limited as long as it can be used for polishing. For example, a polyurethane resin material obtained by reacting a polyisocyanate compound containing a urethane bond with a curing agent can be used.

[0059] The polishing layer 4 preferably comprises a polyurethane resin material having air bubbles. Further, depending on the form of the air bubbles in the polyurethane resin material, they are classified into closed cells in which a plurality of air bubbles exist independently and open cells in which a plurality of air bubbles are connected by communication holes. Among these, the polyurethane resin material used in the present invention preferably has closed cells, and more preferably is a polyurethane resin material containing a polyurethane resin and hollow fine particles dispersed in the polyurethane resin.

[0060] A polyurethane resin material having closed cells can be formed by using hollow fine particles having an outer shell and a hollow interior. As the hollow fine particles, commercially available ones may be used, or those obtained by synthesis 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 monomers constituting these resins can be mentioned. Further, commercially available hollow fine particles include, but are not limited to, for example, Expancel series (trade name of Akzo Nobel), Matsumoto Microsphere (trade name of Matsumoto Yushi Co., Ltd.), and the like.

[0061] The shape of the hollow microparticles in the polyurethane sheet is not particularly limited, and for example, they may be spherical or substantially spherical. The average particle size 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. The average particle size can be measured by a laser diffraction particle size distribution measuring device (for example, Mastersizer - 2000 manufactured by Malvern Panalytical Ltd.).

[0062] 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, per 100 parts by mass of the urethane prepolymer.

[0063] In addition to the above components, within a range that does not impair the effects of the present invention, a conventionally used foaming agent may be used in combination with the hollow microparticles, 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 foaming agents mainly composed of hydrocarbons having 5 or 6 carbon atoms. Examples of the hydrocarbons include chain hydrocarbons such as n - pentane and n - hexane, and alicyclic hydrocarbons such as cyclopentane and cyclohexane.

[0064] As a method for manufacturing the polishing layer 4 using a urethane - bond - containing polyisocyanate compound and a curing agent, for example, there is a manufacturing method including at least a preparation step of preparing materials; a mixing step of obtaining at least a mixed solution of the materials; a molded body forming step of molding a polyurethane resin molded body from the mixed solution; and a polishing layer forming step of forming a polishing layer having a polishing surface for polishing an object to be polished from the polyurethane resin molded body. These steps are the same as the manufacturing method of the end - point detection window, except that it is not necessarily required to use a phenolic antioxidant and a phosphorus - based antioxidant, so detailed description is omitted. This description does not prevent the polishing layer 4 other than the end - point detection window 5 from using both a phenolic antioxidant and a phosphorus - based antioxidant, and if necessary, both a phenolic antioxidant and a phosphorus - based antioxidant may also be used for the polishing layer 4.

[0065] <Method for manufacturing a polishing layer provided with an end point detection window> The polishing layer 4 of the polishing pad 3 of the present invention is provided with at least one end point detection window 5. The polishing layer 4 provided with this end point detection window 5 will be described. As shown in FIG. 5, first, a columnar end point detection window 5 is manufactured. As this manufacturing method, the material may be extrusion-molded, or may be formed into a columnar shape by grinding or the like. In addition, the side surface of the end point detection window 5 can be provided with unevenness or a thread structure as necessary to facilitate fitting with the polishing layer 4. Next, a urethane prepolymer, a curing agent, and hollow fine particles that are the materials of the polishing layer 4 are supplied into a mixer and stirred and mixed. With the columnar end point detection window 5 provided, the material of the polishing layer 4 is cured around it to form a block-shaped polishing layer 4 provided with the columnar end point detection window 5. Finally, the polishing layer 4 can be cut out so as to have the shape of the desired polishing pad 3 to obtain a polishing layer 4 having a predetermined shape. The polishing layer 4 provided with the end point detection window 5 can be formed as described above, but is not limited thereto.

[0066] The polishing layer 4 provided with the end point detection window 5 thus obtained has a double-sided tape attached to the surface on the side opposite to the polishing surface of the polishing layer 4. There is no particular limitation on the double-sided tape, and it can be arbitrarily selected and used from among the double-sided tapes known in the art.

[0067] Further, the polishing pad 3 of the present invention may have a single-layer structure composed only of the polishing layer 4, or may have a multi-layer structure in which another layer (a lower layer, a support layer, a cushion layer 6 in FIGS. 3 and 5) is bonded to the surface on the side opposite to the polishing surface of the polishing layer 4. When having a multi-layer structure, the plurality of layers may be bonded and fixed to each other using a double-sided tape or an adhesive, and if necessary, while applying pressure. 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 among the double-sided tapes and adhesives known in the art. The cushion layer 6 is provided with a through hole 6a in advance at a position corresponding to the end point detection window 5.

[0068] Furthermore, the polishing pad 3 of the present invention may, if necessary, grind the surfaces and / or the back surfaces of the polishing layer 4 and the endpoint detection window 5, or may perform groove processing or embossing on the surface. 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 examples thereof include shapes such as a lattice type, a concentric circle type, and a radial type.

[0069] When using the polishing pad 3 of the present invention, the polishing pad 3 is attached to the polishing surface plate 10 of the polishing machine 1 so that the polishing surface of the polishing layer 4 faces the object to be polished. Then, while supplying slurry, the polishing surface plate is rotated to polish the processing surface of the object to be polished.

Example

[0070] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited by these examples.

[0071] In each of the examples and comparative examples, unless otherwise specified, "part" means "part by mass".

[0072] <Example 1> (Manufacture of endpoint detection window) 100 parts of an isocyanate group-terminated urethane prepolymer with an NCO equivalent of 490, which is obtained by reacting 2,4-tolylene diisocyanate (2,4-TDI), 2,6-tolylene diisocyanate (2,6-TDI), poly(oxytetramethylene) glycol (PTMG) with a number average molecular weight of 650, and diethylene glycol (DEG), were charged into the first liquid tank and kept warm at 60°C. Next, separately from the first liquid, 0.6 part of bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionic acid][ethylenebis(oxyethylene)] as a phenolic antioxidant and 0.4 part of triphenyl phosphite as a phosphorus-based antioxidant were added to and mixed with 23.7 parts of MOCA as a curing agent to obtain a mixed solution. The obtained mixed solution was kept warm at 120°C in the second liquid tank. The liquids in the first liquid tank and the second liquid tank were respectively injected into a mixer equipped with two inlets from their respective inlets. After injecting the two injected liquids into a mold of a molding machine preheated to 80°C while mixing and stirring, the mold was clamped and heated at 80°C for 30 minutes for primary curing. After demolding the primary-cured molded product, it was secondarily cured in an oven at 120°C for 4 hours to obtain a urethane resin molded product used as an end point detection window. At this time, the R value representing the equivalent ratio of the amino groups present in the curing agent to the isocyanate groups present at the terminals in the isocyanate group-terminated urethane prepolymer was adjusted to be 0.90.

[0073] (Manufacture of the polishing layer) One hundred parts of an isocyanate group-terminated urethane prepolymer having an NCO equivalent of 455, which is obtained by reacting one part of 2,4-tolylene diisocyanate (2,4-TDI), poly(oxytetramethylene) glycol (PTMG) having a number average molecular weight of 1000, poly(oxytetramethylene) glycol (PTMG) having a number average molecular weight of 650, and diethylene glycol (DEG), was mixed with 2.7 parts of hollow fine particles having an average particle size of 8.5 μm and unexpanded, in which the shell portion is made of an acrylonitrile-vinylidene chloride copolymer and isobutane gas is encapsulated in the shell. The mixture was charged into a first liquid tank and kept warm at 60°C. Next, separately from the first liquid, 25.8 parts of MOCA was added and mixed as a curing agent, and the mixture was kept warm at 120°C in a second liquid tank. The liquids in the first liquid tank and the second liquid tank were respectively injected into a mixer equipped with two inlets from the respective inlets. At this time, the R value representing the equivalent ratio of the amino groups present in the curing agent to the isocyanate groups present at the terminals in the isocyanate group-terminated urethane prepolymer was adjusted to 0.90. The end point detection window was installed in the mold, and after injecting the two injected liquids into the mold of a molding machine preheated to 80°C while mixing and stirring, the mold was clamped and heated at 80°C for 30 minutes for primary curing. After demolding the primary-cured molded product, it was secondary-cured in an oven at 120°C for 4 hours to obtain a urethane resin molded product. After the obtained urethane resin molded product was allowed to cool to 25°C, it was heated again in an oven at 120°C for 5 hours and then sliced to a thickness of 1.3 mm to obtain a polishing layer. Furthermore, a double-sided tape was attached to the surface of the polishing layer opposite to the polished surface, and it was bonded to a cushion layer to obtain a polishing pad.

[0074] When a test sample was polished using the polishing pad composed of the obtained end point detection window and the obtained polishing layer, stable end point detection was possible by the light passing through the end point detection window.

[0075] <Example 2, Comparative Examples 1 to 3> Endpoint detection window samples of Example 2 and Comparative Examples 1 to 3 were obtained in the same manner as obtaining the endpoint detection window of Example 1, except that the materials were changed as follows. In Example 2, 0.4 parts of the same phenolic antioxidant as in Example 1 and 0.6 parts of the same phosphorus-based antioxidant as in Example 1 were added to prepare an end point detection window. In Comparative Example 1, an end point detection window was prepared without adding a phenolic antioxidant and a phosphorus-based antioxidant. In Comparative Example 2, 0.6 parts of only the same phenolic antioxidant as in Example 1 was added to prepare an end point detection window. In Comparative Example 3, 0.6 parts of only the same phosphorus-based antioxidant as in Example 1 was added to prepare an end point detection window.

[0076] <Light transmittance> Samples of the end point detection windows of Examples 1 to 2 and Comparative Examples 1 to 3 were processed into a size of 60 mm in length × 20 mm in width × 1.3 mm in thickness, and the light transmittance was measured. The measuring instrument used was a U-3210 Spectro Photometer manufactured by Hitachi, Ltd. Those with a light transmittance of 80% or more at wavelengths of 400 nm to 700 nm are marked as ○, and those with a light transmittance of less than 80% are marked as ×, and the results are shown in Table 1.

[0077] <Light resistance test> Samples of the end point detection windows of Examples 1 to 2 and Comparative Examples 1 to 3 were processed into a size of 110 mm in length × 60 mm in width × 1.3 mm in thickness, and in accordance with JIS B 7751 (2007), using an F-type apparatus, a light resistance test was carried out for 25 hours at a black panel temperature of 63°C ± 3°C. The testing machine used for the light resistance test was an ultraviolet auto fade meter U48AU manufactured by Suga Test Instruments Co., Ltd. For the light transmittance of the samples after the light resistance test, those with a light transmittance of 80% or more at wavelengths of 400 nm to 700 nm are marked as ○, and those with a light transmittance of less than 80% are marked as ×, and the results are shown in Table 1.

[0078] <Color measurement> Samples of the end - point detection windows of Examples 1 to 2 and Comparative Examples 1 to 3 before and after being subjected to the light - resistance test were each measured using a color difference meter (colorimeter: CM - 700d manufactured by Konica Minolta Japan). The measurement illuminant was a D65 light source, and the measurement conditions were: (de: 8°) Sa10W10. Color measurement was performed by measuring reflected light, and the chromaticity b*, yellowness change Δb*, and color difference ΔE* were obtained. (The chromaticity of yellow before the light - resistance test was designated as b*1, and the chromaticity of yellow after the light - resistance test was designated as b*2. The yellowness change (difference in yellowness) was designated as Δb*). The results are shown in Table 1. The color measurement was carried out in accordance with the spectroscopic measurement method of JIS Z 8722 (2009). Also, the calculation of the color difference was performed in accordance with JIS Z 8781 - 4 (2013). The number of measurements was 3 times, and the average value was taken as the result.

[0079] <Tensile Test> Samples of the end - point detection windows of Examples 1 to 2 and Comparative Examples 1 to 3 before and after being subjected to the light - resistance test were each subjected to a tensile test, and the results of obtaining the tensile strength are shown in Table 1. The tensile test was carried out on samples punched into the shape of No. 3 dumbbell in accordance with JIS K 7312 (1996) under the conditions of 20°C and 60% RH. An RTC series was used as the tensile testing machine, with a full - scale load of 20 kgf and a test speed of 100 mm / min.

[0080]

Table 1

[0081] Explanation of Symbols 1 Polishing device 2 Incident light 2a, 2b Reflected light 3 Polishing pad 4, 41, 42 Polishing layer 4a Surface of the polishing layer 5 End - point detection window 5a Surface of the end - point detection window 6 Cushion layer 7 Adhesive layer 8 Workpiece to be polished 9 Slurry 10 Polishing platen 11 Substrate 12 Thin film 13 Light source 14 Optical sensor 15 Abrasive grains, grinding debris 16 Holding surface plate

Claims

1. A polishing pad having a polishing layer provided with an end point detection window, wherein the end point detection window has a difference in yellow chromaticity before and after a light resistance test of 20.00 or less when a light resistance test is carried out at a black panel temperature of 63 ° C. ± 3 ° C for 25 hours in accordance with JIS B 7751 (2007), The yellow chromaticity is the chromaticity b* expressed in the L*a*b* color space, The ratio of the tensile strength after the light resistance test to the tensile strength before the light resistance test is 0.85 or more, The end point detection window contains a polyurethane resin, a polyurea resin, or a polyurethane-polyurea resin, The end point detection window contains a phenolic antioxidant and a phosphorus-based antioxidant, Polishing pad.

2. The polishing pad according to claim 1, wherein the end point detection window has a ratio of the yellow chromaticity after the light resistance test to the yellow chromaticity before the light resistance test of 2.0 or less.

3. The polishing pad according to claim 1 or 2, wherein the end point detection window has a yellow chromaticity before the light resistance test of 0 to 30.

00.

4. The end point detection window has a color difference before and after the light resistance test of 25.0 or less, and The color difference is represented by the following formula: ΔE* = [(L*2 - L*1) ２ + (a*2 - a*1) ２ + (b*2 - b*1) ２ ] １／２ (where L*1 is the lightness before the light resistance test, a*1 and b*1 are the chromaticities before the light resistance test, respectively, L*2 is the lightness after the light resistance test, and a*2 and b*2 are the chromaticities after the light resistance test, respectively). Obtained by The polishing pad according to any one of claims 1 to 3.

Images