Polishing pad including a polishing layer with an endpoint detection window - Patents.com

Abstract

To provide a polishing pad which has enhanced grindability than a polishing layer, and has an end point detection window having high light transmittance.SOLUTION: A polishing pad 3 includes a polishing layer 4 having a window 5 for end point detection, in which the window for end point detection is a cured product of a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent, the isocyanate-terminated urethane prepolymer is a reaction product of a polyol component and a polyisocyanate component, and the polyol component contains polyether polycarbonate diol.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a polishing pad. The polishing pad of the present invention is provided with an end point detection window that transmits light. Light is irradiated by an optical means of a polishing device and passes through the end point detection window. The transmitted light is reflected by the workpiece and passes through the end point detection window again. The reflected light is detected by an optical sensor, allowing the polishing state of the workpiece (polishing end point) to be confirmed. [Background technology]

[0002] The endpoint detection window is made of a transparent material to transmit light in the visible light region (wavelength: 400 nm to 800 nm). The endpoint detection window is often provided on the same plane as the polishing layer to prevent slurry from accumulating and reducing the accuracy of endpoint detection. However, transparent materials generally have a higher density than the polishing layer and are less abrasive than the polishing layer, so the endpoint detection window gradually protrudes during polishing, which can have a negative effect on polishing.

[0003] Patent Document 1 discloses a polishing pad equipped with an end point detection window that has higher abrasive properties than the polishing layer, and that uses a hard polyurethane material obtained by reacting a prepolymer (Adiprene L-325) containing polytetramethylene ether glycol (PTMG) as a high molecular weight polyol with 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), a diamine curing agent. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-001647 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the prepolymer contains PTMG, there is a problem that the transparency is low due to high crystallinity, and the light transmittance is reduced. Therefore, the object of the present invention is to provide a polishing pad having an end point detection window with high light transmittance and improved grinding performance compared to the polishing layer. [Means for solving the problem]

[0006] The present invention provides the following aspects. [1] A polishing pad comprising a polishing layer having an endpoint detection window, the end point detection window is a cured product of a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent, the isocyanate-terminated urethane prepolymer is a reaction product of a polyol component and a polyisocyanate component, A polishing pad characterized in that the polyol component contains a polyether polycarbonate diol. [2] The polyether polycarbonate diol is represented by the following formula (I): [ka] (In the above formula (I), R 1 is a divalent hydrocarbon group having 2 to 10 carbon atoms, and multiple R 1 may be the same or different, n is an integer from 2 to 30; m is an integer from 1 to 20. The polishing pad according to [1], [3] The polishing pad according to [1] or [2], wherein the polyether polycarbonate diol has a number average molecular weight of 200 to 5,000. [4] The polishing pad according to any one of [1] to [3], wherein the polyisocyanate component contains tolylene diisocyanate. [5] The polishing pad according to any one of [1] to [4], wherein the curing agent contains 3,3'-dichloro-4,4'-diaminodiphenylmethane. [6] The polishing pad according to any one of [1] to [5], wherein the polyether polycarbonate diol contains a structural unit derived from polytetramethylene ether glycol (PTMG). [7] The polishing pad described in any one of [1] to [6], wherein the polishing layer is a cured product of a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent, the isocyanate-terminated urethane prepolymer is a reaction product of a polyol component and a polyisocyanate component, and the polyol component contains at least one selected from polytetramethylene ether glycol and polypropylene glycol. [8] A method for producing a polishing pad according to any one of [1] to [7], (a) a step of pouring a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent to be used as a window member into a formwork and curing the composition to produce a window member; (b) placing a window member in the mold, pouring in a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent to form the polishing layer, and curing the composition to produce a urethane block in which the polishing layer and the window member are integrated; and (c) A process of slicing the urethane block with the polishing layer and window member integrated together. A method comprising: [9] A method for polishing a surface of an optical material or a semiconductor material, comprising a step of polishing the surface of the optical material or the semiconductor material using the polishing pad described in any one of [1] to [7]. Effect of the Invention

[0007] According to the present invention, it is possible to provide a polishing pad having an end point detection window with high light transmittance and improved grinding performance compared to the polishing layer. The end point detection window in the polishing pad of the present invention has higher grinding performance than the polishing layer, but has a relatively small difference in physical properties from the highly polished layer, has high light transmittance, and provides high endpoint detection accuracy. [Brief description of the drawings]

[0008] [Figure 1]FIG. 1 is an overall view of a polishing apparatus. [Diagram 2] 2 is an enlarged cross-sectional view of a polishing pad installed in a polishing apparatus. FIG. [Diagram 3] 1A to 1C are diagrams illustrating a manufacturing process for a polishing pad according to the present invention. [Figure 4] 1 is a graph comparing the tensile strength of the polyurethane resins obtained in Example 1 and Comparative Example 1. [Diagram 5] 1 is a graph comparing the tensile elongation of the polyurethane resins obtained in Example 1 and Comparative Example 1. [Figure 6] 1 is a graph comparing the tear strength of polyurethane resins obtained in Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (action) The present inventors have conducted extensive research to solve the problem of providing a polishing pad with an end point detection window having high light transmittance and improved grindability compared to the polishing layer, and have unexpectedly found that this problem can be solved when the polyol component forming the isocyanate-terminated urethane prepolymer contains polyether polycarbonate diol (PEPCD). The present invention was discovered experimentally and is not bound by any theory, but it is believed that the structural units derived from PTMG are linked by relatively rigid carbonate bonds, making it difficult for the structural units derived from PTMG to associate with each other intramolecularly, and the polyurethane after curing has a property that is difficult to crystallize, and therefore a polyurethane window member having high transparency (high light transmittance) but low mechanical properties such as tensile strength and tear strength (i.e., high grindability) can be obtained.

[0010] The polishing pad, the method for producing the polishing pad, and the method for polishing the surface of an optical material or a semiconductor material of the present invention will be described below.

[0011] The polishing pad of the present invention is characterized in that the polishing layer has a window for end point detection. (a) a step of pouring a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent to be a window member into a formwork and curing the composition to produce a window member, particularly a window member having a rod-like shape; (b) placing a window member in the mold, pouring in a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent to form the polishing layer, and curing the composition to produce a urethane block in which the polishing layer and the window member are integrated; and (c) A process of slicing the urethane block with the polishing layer and window member integrated together. The composition can be produced by a method comprising the steps of:

[0012] [Window material] The window member of the present invention is a cured product of a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent, the isocyanate-terminated urethane prepolymer being a reaction product of a polyol component and a polyisocyanate component, and the polyol component containing a polyether polycarbonate diol (PEPCD), in particular, a polyether polycarbonate diol containing a structural unit derived from polytetramethylene ether glycol (PTMG).Preferred polyether polycarbonate diols include, for example, those represented by the following formula (I): [ka] (In the above formula (I), R 1 is a divalent hydrocarbon group having 2 to 10 carbon atoms, and multiple R 1 may be the same or different, n is an integer from 2 to 30; m is an integer from 1 to 20. Examples of the above-mentioned are represented by the following formula:

[0013] The window member is formed by preparing a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent, and curing the curable resin composition in a mold. The curable resin composition used for the window member does not contain additives that inhibit transparency, such as a foaming agent or a colorant. In addition, various additives such as antioxidants and ultraviolet absorbers may be appropriately contained to prevent discoloration.

[0014] (Isocyanate-terminated urethane prepolymer) The isocyanate-terminated urethane prepolymer is a product obtained by reacting a polyol component with a polyisocyanate component, and the present invention is particularly characterized in that the polyol component contains a polyether polycarbonate diol.

[0015] The NCO equivalent (g / eq) of the isocyanate-terminated urethane prepolymer is preferably less than 600, more preferably 350 to 550, and most preferably 400 to 500. By having the NCO equivalent (g / eq) within the above numerical range, a polishing pad with appropriate polishing performance can be obtained.

[0016] (Polyol component) In the above formula (I) representing the polyether polycarbonate diol, R 1 is a divalent hydrocarbon group having 2 to 10 carbon atoms, R 1 Examples of R include ethylene, n-propylene, isopropylene, n-butylene, isobutylene, 1,1-dimethylethylene, n-pentylene, 2,2-dimethylpropylene, and 2-methylbutylene, and n-butylene and 2-methylbutylene are particularly preferred. 1 may be the same or different, but is preferably the same.

[0017] In the above formula (I), n is an integer of 2 to 30, preferably an integer of 3 to 15, and more preferably an integer of 3 to 10. In the above formula (I), m is an integer of 1 to 20, preferably an integer of 1 to 10, and more preferably an integer of 1 to 5.

[0018] The polyether polycarbonate diol preferably contains a structural unit derived from polytetramethylene ether glycol, and the structural unit derived from polytetramethylene ether glycol is represented by -(R 1 -O) n The number average molecular weight of the structural unit derived from polytetramethylene ether glycol is preferably 100 to 1500, more preferably 150 to 1000, and most preferably 200 to 850. The number average molecular weight of the polyether polycarbonate diol is preferably 200 to 5000, more preferably 500 to 3000, and most preferably 800 to 2500.

[0019] The number average molecular weight of the structural unit derived from polytetramethylene ether glycol and the number average molecular weight of the polyether polycarbonate diol can be measured as a polystyrene-equivalent molecular weight based on gel permeation chromatography (GPC) under the following conditions. <Measurement conditions> Column: Ohpak SB-802.5HQ (exclusion limit 10,000) Mobile phase: 5mM LiBr / DMF Flow rate: 0.5ml / min (26kg / cm 2 ) Oven: 60℃ Detector: RI 40℃ Sample volume: 20 μl

[0020] The content of the polyether polycarbonate diol in the entire isocyanate-terminated urethane prepolymer is preferably 25 to 75% by weight, more preferably 35 to 65% by weight, and most preferably 40 to 60% by weight. By having the content of the polyether polycarbonate diol within the above numerical range, good transparency and good grindability can be obtained.

[0021] The polyol component other than the polyether polycarbonate diol contained in the isocyanate-terminated urethane prepolymer may be a low molecular weight polyol, a high molecular weight polyol other than the polyether polycarbonate diol, or a combination thereof. In the present invention, the low molecular weight polyol is a polyol having a number average molecular weight of 30 to 300, and the high molecular weight polyol is a polyol having a number average molecular weight of more than 300. The number average molecular weight of the low molecular weight polyol and the high molecular weight polyol other than the polyether polycarbonate diol can be measured by the same method as that shown in the number average molecular weight of the structural unit derived from the polytetramethylene ether glycol and the polyether polycarbonate diol.

[0022] Examples of the low molecular weight polyol include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, or combinations thereof.

[0023] Examples of high molecular weight polyols other than the above polyether polycarbonate diols include polyether polyols such as polytetramethylene ether glycol (PTMG), polyethylene glycol, and polypropylene glycol; polyester polyols such as the reaction product of ethylene glycol with adipic acid and the reaction product of butylene glycol with adipic acid; Polycarbonate polyols; polycaprolactone polyols; or combinations thereof.

[0024] The content of the polyether polycarbonate diol in the total high molecular weight polyol is preferably 80 to 100% by weight, more preferably 85 to 100% by weight, and most preferably 90 to 100% by weight. When the content of the polyether polycarbonate diol is within the above range, good transparency and good grindability can be obtained.

[0025] (Polyisocyanate component) The polyisocyanate component contained in the isocyanate-terminated urethane prepolymer is For example, 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'-dimethyldiphenylmethane-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, or a combination thereof. Among these, it is preferable to use tolylene diisocyanates such as 2,6-tolylene diisocyanate (2,6-TDI) and 2,4-tolylene diisocyanate (2,4-TDI) from the viewpoint of the polishing characteristics and mechanical strength of the resulting polishing pad.

[0026] (hardening agent) The curing agent contained in the curable resin composition may, for example, be an amine-based curing agent described below. Examples of polyamines constituting the amine-based curing agent include diamines, such as alkylenediamines such as ethylenediamine, propylenediamine, and hexamethylenediamine; diamines having an aliphatic ring such as isophoronediamine and dicyclohexylmethane-4,4'-diamine; diamines having an aromatic ring such as 3,3'-dichloro-4,4'-diaminodiphenylmethane (also known as methylenebis-o-chloroaniline) (hereinafter abbreviated as MOCA); diamines having a hydroxyl group such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine, particularly hydroxyalkylalkylenediamines; or combinations thereof. Also usable are trifunctional triamine compounds and polyamine compounds having 4 or more functional groups.

[0027] A particularly preferred curing agent is the above-mentioned MOCA, the chemical structure of which is as follows:

[0028] [ka]

[0029] The total amount of hardener is the ratio of the moles of NH of the hardener to the moles of NCO of the isocyanate-terminated urethane prepolymer. 2 Ratio of moles of (NH 2The amount used is such that the ratio (number of moles of NCO / number of moles of NCO) is preferably 0.7 to 1.1, more preferably 0.75 to 1.0, and most preferably 0.8 to 0.95.

[0030] [Polishing layer] The window member created in step (a) becomes part of the polishing layer through steps (b) of placing the window member in a formwork, pouring in and curing a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent that will form the polishing layer, and producing a urethane block in which the polishing layer and the window member are integrated; and (c) slicing the urethane block in which the polishing layer and the window member are integrated.

[0031] The polishing pad of the present invention has a polishing layer containing polyurethane resin. The polishing layer is disposed in a position directly contacting the material to be polished, and the other parts of the polishing pad may be made of a material for supporting the polishing pad, for example, a material having high elasticity such as rubber. Depending on the rigidity of the polishing pad, the polishing layer can be made into a polishing pad.

[0032] The polishing pad of the present invention has a shape similar to that of a conventional polishing pad having an end point detection window, and can be used in the same way as a conventional polishing pad. For example, the polishing pad can be rotated while the polishing layer is pressed against the material to be polished, or the material to be polished can be rotated while the polishing layer is pressed against the material to be polished. FIG. 1 shows an example of polishing by pressing the material to be polished against the polishing layer while rotating. The polishing device 1 of FIG. 1 is configured to polish the material to be polished 8 by pressing the material to be polished 8 against the upper surface of the polishing pad 3 from above while rotating with a top ring 16 while supplying a slurry 9 to the center of a rotating table 10 on which the polishing pad 3 is laid. FIG. 2 is an enlarged cross-sectional view of the polishing pad 3. The polishing pad having an end point detection window 5 and a polishing layer 4 contacts the surface 4a and 5a of the polishing layer 4 and the end point detection window 5 on the side of the material to be polished, and polishing is performed. The polishing pad 3 is bonded to the rotating table 10 via a cushion layer 6. A light source 13 and an optical sensor 14 are provided under the table 10, and each component is arranged so that measurement light passes through the opening in the table and the end point detection window 5 and is reflected by the workpiece, and the reflected light passing through the end point detection window 5 and the opening in the table can be observed by the sensor 14. The polishing state of the workpiece can be monitored from the change in the reflected light.

[0033] The polishing pad of the present invention can be produced by a commonly known manufacturing method such as molding or slab molding, except that a window member is placed in a mold in advance. First, a block of polyurethane is formed by such a manufacturing method, and the block is sliced ​​into a sheet, and an abrasive layer made of polyurethane resin is formed, and the sheet is laminated to a support, for example, via a cushion layer. Alternatively, the abrasive layer can be formed directly on the support.

[0034] More specifically, the polishing layer is attached with a double-sided tape on the side opposite to the polishing surface of the polishing layer, and cut into a predetermined shape to become the polishing pad of the present invention. There is no particular limitation on the double-sided tape, and it can be arbitrarily selected from the double-sided tapes known in the art. In addition, the polishing pad of the present invention may be 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 side opposite to the polishing surface of the polishing layer.

[0035] The polishing layer can be made of a foamed polyurethane resin, and foaming can be performed by dispersing a foaming agent containing micro hollow spheres in the polyurethane resin. In this case, a curable resin composition containing an isocyanate-terminated urethane prepolymer, a curing agent, and a foaming agent is prepared, and the curable resin composition is foamed and cured to form the polishing layer.

[0036] The curable resin composition may be, for example, a two-liquid composition prepared by mixing liquid A containing an isocyanate-terminated urethane prepolymer with liquid B containing a curing agent component. Other components may be added to liquid A or liquid B, but if problems arise, the composition may be divided into multiple liquids and mixed to form a composition consisting of three or more liquids.

[0037] (Micro Hollow Spheres) In the present invention, the curable resin composition may further contain hollow microspheres. A foam can be formed by mixing the hollow microspheres with a polyurethane resin. The hollow microspheres refer to unfoamed heat-expandable microspheres consisting of an outer shell (polymer shell) made of a thermoplastic resin and a low-boiling point hydrocarbon encapsulated in the outer shell, and those obtained by thermally expanding the unfoamed heat-expandable microspheres. As the polymer shell, for example, a thermoplastic resin such as an acrylonitrile-vinylidene chloride copolymer, an acrylonitrile-methyl methacrylate copolymer, or a vinyl chloride-ethylene copolymer can be used. Similarly, as the low-boiling point hydrocarbon encapsulated in the polymer shell, for example, isobutane, pentane, isopentane, petroleum ether, or a combination thereof can be used.

[0038] [Other ingredients] In addition, catalysts and the like that are generally used in the industry may be added to the curable resin composition. The polyisocyanate component can also be added later to the curable resin composition. The weight ratio of the additional polyisocyanate component to the total weight of the isocyanate-terminated urethane prepolymer and the additional polyisocyanate component is preferably 0.1 to 10% by weight, more preferably 0.5 to 8% by weight, and particularly preferably 1 to 5% by weight. As the polyisocyanate component additionally added to the polyurethane resin curable composition, the above-mentioned polyisocyanate components can be used without particular limitation, but 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI) is preferred.

[0039] [Specific example of a method for manufacturing a polishing pad] The method for producing a polishing pad of the present invention will be specifically described with reference to FIG. Process (1): A curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent to form the window member is poured into the formwork and cured to produce a rod-shaped window member 5. Process (2): A window member 5 is placed in the formwork, and a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent to form the polishing layer 4 is poured in and cured to produce a urethane block in which the polishing layer 4 and window member 5 are integrated. Process (3): The urethane block in which the polishing layer 4 and the window member 5 are integrated is sliced. Process (4): The cushion layer 6, which has a hole 6a drilled in advance, is attached to the polishing layer 4 via an adhesive layer so that the hole 6a coincides with the window member 5. The polishing pad of the present invention, which includes the polishing layer 4, the window member 5, and the cushion layer 6, is attached to the turntable 10 of a polishing apparatus via an adhesive layer.

[0040] The method for polishing a surface of an optical or semiconductor material of the present invention includes a step of polishing the surface of the optical or semiconductor material using the polishing pad described above. The method for polishing a surface of an optical or semiconductor material of the present invention can further include a step of supplying a slurry to the surface of the polishing pad, the surface of the optical or semiconductor material, or both. EXAMPLES

[0041] The present invention will be experimentally described by the following examples, but the following description is not intended to limit the scope of the present invention to the following examples. 1.Material The materials used in the examples and comparative examples described later are listed below. Isocyanate-terminated urethane prepolymer: Prepolymer (1): A urethane prepolymer having an NCO equivalent of 420, which contains, as a polyisocyanate component, 43.8% by weight of 2,4-tolylene diisocyanate, and, as a polyol component, 50.4% by weight of polyether polycarbonate diol (PEPCD1000) represented by the above formula (I), which contains structural units derived from polytetramethylene ether glycol having a number average molecular weight of 250 and has a number average molecular weight of 1000, and 5.8% by weight of diethylene glycol. *The content (wt%) of each component means the value when the entire urethane prepolymer is taken as 100 wt%. The same applies to the prepolymer (2) below. Prepolymer (2): A urethane prepolymer having an NCO equivalent of 420, containing 40.7% by weight of 2,4-tolylene diisocyanate as a polyisocyanate component, and containing 27.9% by weight of polytetramethylene ether glycol having a number average molecular weight of 650, 27.9% by weight of polytetramethylene ether glycol having a number average molecular weight of 1,000, and 3.5% by weight of diethylene glycol as polyol components.

[0042] Hardener: MOCA 3,3'-dichloro-4,4'-diaminodiphenylmethane (also known as methylenebis-o-chloroaniline) (NH 2 equivalent weight=133.5)

[0043] Micro Hollow Spheres: Expancel461DU20 (manufactured by Nippon Phillite Co., Ltd.) Expancel461DE20d70 (manufactured by Nippon Phillite Co., Ltd.)

[0044] 2. Measurement of thickness, density, D hardness, tensile strength, tensile elongation, tear strength and light transmittance (Thickness) The thickness (mm) of the urethane sheet was measured in accordance with the Japanese Industrial Standard (JIS K 6550).

[0045] (density) Density of urethane sheet (g / cm 3 ) was measured in accordance with the Japanese Industrial Standard (JIS K 6505).

[0046] (D hardness) The D hardness of the urethane sheet was measured using a D-type hardness tester in accordance with the Japanese Industrial Standards (JIS-K-6253). Here, the measurement sample was obtained by stacking multiple urethane sheets as necessary so that the total thickness was at least 4.5 mm.

[0047] (tensile strength, tensile elongation) The urethane sheet was cut into a dumbbell shape as specified in the tensile strength measurement of the Japanese Industrial Standard (JIS6550), and the tensile strength (kg / mm 2 ) and tensile elongation (%) were measured.

[0048] (tear strength) The urethane sheet was cut into a rectangular shape with a notch as specified in the tear strength measurement of the Japanese Industrial Standard (JIS6550), and the tear strength (kg / mm 2 ) was measured. (light transmittance) The end point detection window sample was processed to a length of 60 mm, width of 20 mm, and thickness of 1.3 mm, and the light transmittance was measured using a Hitachi U-3210 Spectro Photometer.

[0049] Example 1 A window member composition was prepared by mixing 100 g of the above prepolymer (1) with 28.6 g of a curing agent (MOCA). This window member composition was poured into a mold and cured primarily at 80°C for 30 minutes. The formed resin molded body was removed from the mold and cured secondary at 120°C for 4 hours in an oven. In this way, a transparent rod-shaped window member was obtained.

[0050] Comparative Example 1 A transparent rod-shaped window member was obtained in the same manner as in Example 1, except that 100 g of prepolymer (2) was used as component A instead of 100 g of prepolymer (1) as component A in Example 1.

[0051] The obtained window member was sliced, and the thickness, density, D hardness, tensile strength, tensile elongation, tear strength, and light transmittance were measured. Measurements of tensile strength, tensile elongation, and tear strength were performed under the tensile and tear conditions in Tables 2 and 3 for dry test pieces and wet test pieces after being subjected to the immersion conditions in Table 1 below. Light transmittance was evaluated as ◯ when the light transmittance was 80% or more at wavelengths of 400 nm to 700 nm, and × when the light transmittance was less than 80%. The results are shown in Table 4 and Figures 4 to 6.

[0052] [Table 1]

[0053] [Table 2]

[0054] [Table 3]

[0055] [Table 4]

[0056] The window member used in the present invention, in which the high molecular weight polyol component of the prepolymer is polyether polycarbonate diol (PEPCD), had lower density, D hardness, tensile strength, tensile elongation, and tear strength than the window member of the comparative example in which the high molecular weight polyol component of the prepolymer is polytetramethylene ether glycol. In addition, the window member of Example 1 had a light transmittance of 80% or more at wavelengths of 400 nm to 700 nm, whereas the window member of Comparative Example 1 had a light transmittance of 80% or less. From this, the window member used in the present invention is less likely to crystallize and has high transparency, while having high grinding properties, compared to conventional polyurethane window members, so that the window member alone does not protrude even after being used for polishing for a long time. Furthermore, a polishing test was performed for a predetermined time using polishing pads equipped with the window members of Example 1 and Comparative Example 1, and the window members after the test were observed. As a result, the window member of Example 1 had less adhesion of polishing slurry and pad debris from the polishing pad and had a smaller decrease in light transmittance during polishing, compared to the window member of Comparative Example 1.

Claims

1. 1. A polishing pad comprising a polishing layer having an endpoint detection window, the end point detection window is a cured product of a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent, the isocyanate-terminated urethane prepolymer is a reaction product of a polyol component and a polyisocyanate component, The polishing pad is characterized in that the polyol component contains a polyether polycarbonate diol, the polyether polycarbonate diol contains a structural unit derived from polytetramethylene ether glycol (PTMG), the number average molecular weight of the structural unit derived from polytetramethylene ether glycol is 100 to 250, and the curing agent contains 3,3'-dichloro-4,4'-diaminodiphenylmethane.

2. The polyether polycarbonate diol is represented by the following formula (I): 【Chemistry 1】 (I) (In the above formula (I), R １ is a divalent hydrocarbon group having 2 to 10 carbon atoms, and a plurality of R １ may be the same or different, n is an integer from 2 to 30; m is an integer from 1 to 20. The polishing pad of claim 1 ,

3. 3. The polishing pad according to claim 1, wherein the polyether polycarbonate diol has a number average molecular weight of 200 to 5,000.

4. The polishing pad of any one of claims 1 to 3, wherein the polyisocyanate component comprises tolylene diisocyanate.

5. The polishing pad according to any one of claims 1 to 4, wherein the polishing layer is a cured product of a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent, the isocyanate-terminated urethane prepolymer is a reaction product of a polyol component and a polyisocyanate component, and the polyol component contains at least one selected from polytetramethylene ether glycol and polypropylene glycol.

6. A method for producing a polishing pad according to any one of claims 1 to 5, (a) a step of pouring a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent to be a window member into a mold and curing the composition to produce a window member; (b) placing a window member in the mold, pouring in a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent to form the polishing layer, and curing the composition to produce a urethane block in which the polishing layer and the window member are integrated; and (c) A process of slicing the urethane block having the polishing layer and the window member integrated therein. A method comprising:

7. A method for polishing a surface of an optical or semiconductor material, comprising the step of polishing the surface of the optical or semiconductor material using a polishing pad according to any one of claims 1 to 5.

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