JP7612424B2 - Polishing pad including a polishing layer with an endpoint detection window - Patents.com - Google Patents

Description

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 the 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, and the reflected light is detected by an optical sensor, making it possible to confirm the polishing state of the workpiece (polishing end point).

The endpoint detection window is made of a transparent material so that light in the visible light range (wavelength: 400 nm to 800 nm) can pass through. 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.

Patent Document 1 discloses a polishing pad 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, as the end point detection window, and has an end point detection window that has higher abrasive properties than the polishing layer.

JP 2002-001647 A

However, when the prepolymer contains PTMG, there is a problem in that the high crystallinity results in low transparency and reduced light transmittance. Therefore, the present invention aims to provide a polishing pad with an end point detection window that has improved grinding ability and high light transmittance compared to the polishing layer.

（上記式（Ｉ）中、
Ｒ^１は炭素数２～１０の二価の炭化水素基であり、複数のＲ^１は同一であってもよく、異なるものであってもよく、
ｎは２～３０の整数であり、
ｍは１～２０の整数である。）
で表される、［１］に記載の研磨パッド。
［３］ 前記ポリエーテルポリカーボネートジオールの数平均分子量が２００～５０００である、［１］又は［２］に記載の研磨パッド。
［４］ 前記ポリイソシアネート成分がトリレンジイソシアネートを含む、［１］～［３］のいずれか１つに記載の研磨パッド。
［５］ 前記硬化剤が３，３’－ジクロロ－４，４’－ジアミノジフェニルメタンを含む、［１］～［４］のいずれか１つに記載の研磨パッド。
［６］ 前記ポリエーテルポリカーボネートジオールが、ポリテトラメチレンエーテルグリコール（ＰＴＭＧ）に由来する構造単位を含む、［１］～［５］のいずれか１つに記載の研磨パッド。
［７］ 前記研磨層が、イソシアネート末端ウレタンプレポリマー及び硬化剤を含む硬化性樹脂組成物の硬化物であり、前記イソシアネート末端ウレタンプレポリマーが、ポリオール成分とポリイソシアネート成分との反応生成物であり、前記ポリオール成分が、ポリテトラメチレンエーテルグリコール及びポリプロピレングリコールから選ばれる少なくとも１種を含む、［１］～［６］のいずれか１つに記載の研磨パッド。
［８］ ［１］～［７］のいずれか１つに記載の研磨パッドの製造方法であって、
（ａ）型枠内に、窓部材となるイソシアネート末端ウレタンプレポリマー及び硬化剤を含む硬化性樹脂組成物を流し入れて硬化させ、窓部材を作製する工程；
（ｂ）型枠内に、窓部材を設置し、研磨層となるイソシアネート末端ウレタンプレポリマー及び硬化剤を含む硬化性樹脂組成物を流し入れて硬化させ、研磨層と窓部材を一体化させたウレタンブロックを作製する工程；及び
（ｃ）研磨層と窓部材を一体化させたウレタンブロックをスライスする工程
を含む、方法。
［９］ 光学材料又は半導体材料の表面を研磨する方法であって、［１］～［７］のいずれか１つに記載の研磨パッドを使用して光学材料又は半導体材料の表面を研磨する工程を含む、前記方法。 The present invention provides the following aspects.
[1] A polishing pad including 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):

(In the above formula (I),
R ¹ is a divalent hydrocarbon group having 2 to 10 carbon atoms, and multiple R ^1s 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 comprises 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 according to 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 a window member into a mold and curing the composition to produce a window member;
The method includes the steps of: (b) placing a window member within a formwork, pouring in and curing a curable resin composition containing an isocyanate-terminated urethane prepolymer that will form the polishing layer and a curing agent, 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.
[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 according to any one of [1] to [7].

According to the present invention, it is possible to provide a polishing pad equipped with an end point detection window that has higher grinding ability than the polishing layer and high light transmittance. The end point detection window in the polishing pad of the present invention has higher grinding ability than the polishing layer, but the difference in physical properties with the highly polished layer is relatively small, and the light transmittance is high, resulting in high endpoint detection accuracy.

FIG. 1 is an overall view of a polishing apparatus. 2 is an enlarged cross-sectional view of a polishing pad installed in a polishing apparatus. FIG. 1A to 1C are diagrams illustrating a manufacturing process for a polishing pad according to the present invention. 1 is a graph comparing the tensile strength of the polyurethane resins obtained in Example 1 and Comparative Example 1. 1 is a graph comparing the tensile elongation of polyurethane resins obtained in Example 1 and Comparative Example 1. 1 is a graph comparing the tear strength of polyurethane resins obtained in Example 1 and Comparative Example 1.

(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 PTMG-derived structural units are linked by relatively rigid carbonate bonds, making it difficult for the PTMG-derived structural units to associate with each other in the molecule, 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.

The polishing pad of the present invention, the method for manufacturing the polishing pad, and the method for polishing the surface of an optical material or a semiconductor material are described below.

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 mold and curing the composition to produce a window member, particularly a window member having a rod-like shape;
The polishing layer can be integrated with the window member by a method including the steps of: (b) placing a window member in a formwork, pouring in a curable resin composition containing an isocyanate-terminated urethane prepolymer that will form the polishing layer and a curing agent, and curing the composition to produce 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.

（上記式（Ｉ）中、
Ｒ^１は炭素数２～１０の二価の炭化水素基であり、複数のＲ^１は同一であってもよく、異なるものであってもよく、
ｎは２～３０の整数であり、
ｍは１～２０の整数である。）。
で表されるものが挙げられる。 [Window member]
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, polyether polycarbonate diols represented by the following formula (I):

(In the above formula (I),
R ¹ is a divalent hydrocarbon group having 2 to 10 carbon atoms, and multiple R ^1s may be the same or different;
n is an integer from 2 to 30;
and m is an integer from 1 to 20.
Examples of the above-mentioned are represented by the following formula:

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 foaming agents and colorants. In addition, various additives such as antioxidants and ultraviolet absorbers may be appropriately contained to prevent discoloration.

(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.

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.

(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, and examples of R ¹ include ethylene, n-propylene, isopropylene, n-butylene, isobutylene, 1,1-dimethylethylene, n-pentylene, 2,2-dimethylpropylene, 2-methylbutylene, etc., and particularly preferred are n-butylene, 2-methylbutylene, etc. In the above formula (I), multiple R ^1s may be the same or different, but are preferably the same.

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

The polyether polycarbonate diol preferably contains a structural unit derived from polytetramethylene ether glycol, and the structural unit derived from polytetramethylene ether glycol is preferably the portion represented by -(R ¹ -O) _n - in the above formula (I). 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.

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/ ^cm2 )
Oven: 60°C
Detector: RI 40℃
Sample volume: 20 μl

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.

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, a low molecular weight polyol is a polyol having a number average molecular weight of 30 to 300, and a high molecular weight polyol is a polyol having a number average molecular weight of more than 300. The number average molecular weights 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 for the structural unit derived from polytetramethylene ether glycol and the number average molecular weight of the polyether polycarbonate diol.

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.

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

The content of the polyether polycarbonate diol relative to 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 numerical range, good transparency and good grindability are obtained.

(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, from the viewpoint of the polishing characteristics and mechanical strength of the resulting polishing pad, it is preferable to use tolylene diisocyanates such as 2,6-tolylene diisocyanate (2,6-TDI) and 2,4-tolylene diisocyanate (2,4-TDI).

(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. Trifunctional triamine compounds and polyamine compounds having 4 or more functional groups can also be used.

A particularly preferred hardener is the above-mentioned MOCA, whose chemical structure is as follows:

The total amount of the curing agent is such that the ratio of the number of moles of _NH2 in the curing agent to the number of moles of NCO in the isocyanate-terminated urethane prepolymer (number of moles of _NH2 /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.

[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 window member are integrated; and (c) slicing the urethane block in which the polishing layer and window member are integrated.

The polishing pad of the present invention has a polishing layer containing a polyurethane resin. The polishing layer is disposed in a position in direct contact with 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 highly elastic material such as rubber. Depending on the rigidity of the polishing pad, the polishing layer can be made into a polishing pad.

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 it 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 in 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 with a top ring 16 while rotating, while supplying 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 the end point detection window 5 and the 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. There is a light source 13 and an optical sensor 14 under the table 10, and each component is arranged so that the measurement light is reflected by the workpiece through the opening in the table and the end point detection window 5, and the reflected light that passes through the end point detection window 5 and the opening in the table can be observed by the sensor 14. The polishing condition of the workpiece can be monitored from the change in the reflected light.

The polishing pad of the present invention can be produced by commonly known manufacturing methods such as molding and slab molding, except that a window member is placed in a mold beforehand. 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.

More specifically, the polishing layer is provided with a double-sided tape attached to the side opposite the polishing surface of the polishing layer, and then cut into a predetermined shape to form the polishing pad of the present invention. There are no particular limitations on the double-sided tape, and any double-sided tape known in the art can be selected and used. The polishing pad of the present invention may have a single-layer structure consisting of only the polishing layer, or may be a multi-layer structure in which another layer (lower layer, support layer) is attached to the side opposite the polishing surface of the polishing layer.

The polishing layer can be made of 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 mold.

The curable resin composition can 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. The other components can be placed in either liquid A or liquid B, but if problems arise, the composition can be further divided into multiple liquids and made by mixing three or more liquids.

(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 having 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.

[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 hardening composition, the above-mentioned polyisocyanate components can be used without particular limitation, but 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI) is preferred.

[Specific Example of Method for Manufacturing Polishing Pad]
The method for producing a polishing pad of the present invention will be specifically described with reference to FIG.
Step (1):
A curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent to form the window member is poured into the mold and cured to produce a rod-shaped window member 5.
Step (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 the window member 5 are integrated.
Step (3):
The urethane block having the polishing layer 4 and the window member 5 integrated therewith is sliced.
Step (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.

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

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. Materials The materials used in the examples and comparative examples described below are listed below.
Isocyanate-terminated urethane prepolymer:
Prepolymer (1): A urethane prepolymer with an NCO equivalent of 420, containing 43.8% by weight of 2,4-tolylene diisocyanate as a polyisocyanate component, 50.4% by weight of polyether polycarbonate diol (PEPCD1000) having a number average molecular weight of 1000 and containing structural units derived from polytetramethylene ether glycol having a number average molecular weight of 250, represented by the above formula (I), and 5.8% by weight of diethylene glycol as polyol components. *The content (weight %) of each component means the value when the entire urethane prepolymer is taken as 100% by weight. The same applies to 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 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 1000, and 3.5% by weight of diethylene glycol as polyol components.

・Hardening agent:
MOCA: 3,3'-dichloro-4,4'-diaminodiphenylmethane (also known as methylene bis-o-chloroaniline) (NH ₂ equivalents = 133.5)

・Micro hollow spheres:
Expancel 461DU20 (manufactured by Nippon Phillite Co., Ltd.)
Expancel 461DE20d70 (manufactured by Nippon Phillite Co., Ltd.)

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 Japanese Industrial Standards (JIS K 6550).

(density)
The density (g/cm ³ ) of the urethane sheet was measured in accordance with Japanese Industrial Standards (JIS K 6505).

(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.

(Tensile strength, tensile elongation)
The urethane sheet was cut into a dumbbell shape as specified in the tensile strength measurement of Japanese Industrial Standard (JIS 6550), and the tensile strength (kg/mm ² ) and tensile elongation (%) were measured in accordance with Japanese Industrial Standard (JIS 6550) at a pulling speed of 100 mm/min and a test temperature of 20°C.

(Tear strength)
The urethane sheet was cut into a rectangular shape having a notch as specified in the tear strength measurement of Japanese Industrial Standard (JIS 6550), and the tear strength (kg/mm ² ) was measured in accordance with Japanese Industrial Standard (JIS 6550) at a tear speed of 100 mm/min and a test temperature of 20°C.
(Light Transmittance)
The end point detection window sample was processed to a length of 60 mm, a width of 20 mm, and a thickness of 1.3 mm, and the light transmittance was measured using a Hitachi U-3210 Spectro Photometer.

Example 1
A window member composition was prepared by mixing 100 g of the prepolymer (1) and 28.6 g of a curing agent (MOCA). The 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.

(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.

The obtained window members were 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.

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, while 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 long-term polishing. 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. Compared to the window member of Comparative Example 1, the window member of Example 1 had less adhesion of polishing slurry and pad debris from the polishing pad, and the rate of decrease in light transmittance during polishing was smaller.

Claims (7)

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 . The polyether polycarbonate diol is represented by the following formula (I):
(I)
(In the above formula (I),
R ¹ is a divalent hydrocarbon group having 2 to 10 carbon atoms, and multiple R ^1s 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 , The polishing pad according to claim 1 or 2, wherein the number average molecular weight of the polyether polycarbonate diol is 200 to 5000. The polishing pad according to any one of claims 1 to 3, wherein the polyisocyanate component includes tolylene diisocyanate. 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. A method for producing a polishing pad according to any one of claims 1 to 5 , comprising the steps of:
(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;
The method includes the steps of: (b) placing a window member within a formwork, pouring in and curing a curable resin composition containing an isocyanate-terminated urethane prepolymer that will form the polishing layer and a curing agent, 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. A method for polishing a surface of an optical or semiconductor material, the method 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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