JP2020157415A - Polishing pad - Google Patents

Abstract

To provide a polishing pad which is less in temperature change of a value of tanδ of a polishing layer and is hardly affected by polishing performance.SOLUTION: A polishing pad has a polishing layer formed of a polyurethane resin foam, in which the polyurethane resin is a cured product of a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent, the isocyanate-terminated prepolymer contains a component derived from toluene diisocyanate (TDI) and polypropylene glycol (PPG), a value of tanδ of the polishing layer measured in dynamic viscoelasticity test at a measurement frequency of 10 radian/second in a tensile mode of 0.12 or more at 40°C, and a coefficient of variation of tanδ of the polishing layer at 20-80°C represented by tanδ of the polishing layer in expression [(maximum value of tanδ of polishing layer at 20-80°C)-(minimum value of tanδ of polishing layer at 20-80°C)]/40°C of 50% or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a polishing pad. The polishing pad of the present invention is used for polishing optical materials, semiconductor devices, glass substrates for hard disks, etc., and is particularly suitable for polishing devices in which an oxide layer, a metal layer, etc. are formed on a semiconductor wafer. Used.

Conventionally, for polishing semiconductor devices, prepolymers containing constituents derived from TDI (toluene diisocyanate) and PTMG (polyoxytetramethylene glycol) and diamines such as MOCA (4,4'-methylenebis (2-chloroaniline)) have been used. It is common to use a polishing pad provided with a polyurethane material obtained by reacting a curing agent as a polishing layer. In recent years, with the miniaturization of wiring of semiconductor devices, conventional polishing pads may have insufficient step performance and defect performance, and studies have been made to use polyols as a curing agent for the purpose of softening the polishing pads. ing.

However, even when polyol is used as the curing agent, when PTMG is contained in the prepolymer, the temperature change of the tan δ value of the polishing layer is large, so that the polishing performance is greatly affected by the temperature, and as a result, the desired step performance and defect. Sometimes it did not show performance. Therefore, an object of the present invention is to provide a polishing pad in which the temperature change of the value of tan δ of the polishing layer is small and the influence of the polishing performance by the temperature is small.

The present invention provides the following.
[1]
A polishing pad having a polishing layer made of a polyurethane resin foam.
The polyurethane resin is a cured product of a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent.
The isocyanate-terminated prepolymer contains components derived from toluene diisocyanate (TDI) and polypropylene glycol (PPG).
The value of tan δ of the polishing layer measured by the dynamic viscoelasticity test at a measurement frequency of 10 radians / second and the tensile mode is 0.12 or more at 40 ° C. and the following formula:
[(Maximum value of tan δ of the polishing layer at 20 ° C. to 80 ° C.)-(Minimum value of tan δ of the polishing layer at 20 ° C. to 80 ° C.)] / tan δ of the polishing layer at 40 ° C.
A polishing pad having a fluctuation rate of tan δ of the polishing layer at 20 ° C. to 80 ° C. represented by 50% or less.
[2]
The polishing pad according to [1], wherein the curable resin composition further contains microhollow spheres as a foaming agent.
[3]
The polishing pad according to [1] or [2], wherein the isocyanate-terminated prepolymer further contains a component derived from diethylene glycol (DEG).
[4]
A method for polishing the surface of an optical material or a semiconductor material, which comprises using the polishing pad according to any one of [1] to [3].
[5]
A method for reducing scratches when polishing the surface of an optical material or a semiconductor material by using the polishing pad according to any one of [1] to [3].

According to the present invention, it is possible to provide a polishing pad showing good step performance and defect performance.

It is a graph which shows the result of the dynamic viscoelasticity measurement (DMA) of the polishing layer of the polishing pad of an Example and a comparative example. It is a graph which shows the result of the dynamic viscoelasticity measurement (DMA) of the polishing layer of the polishing pad of an Example and a comparative example.

[Action]
The polishing pad of the present invention is a polishing pad having a polishing layer made of a polyurethane resin foam, wherein the polyurethane resin is a cured product of a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent. The isocyanate-terminated prepolymer contains components derived from toluene diisocyanate (TDI) and polypropylene glycol (PPG), and the value of tan δ of the polishing layer measured by a dynamic viscoelastic test at a measurement frequency of 10 radians / second and a tensile mode is 40. 0.12 or more at ° C and the following formula:
[(Maximum value of tan δ of the polishing layer at 20 ° C. to 80 ° C.)-(Minimum value of tan δ of the polishing layer at 20 ° C. to 80 ° C.)] / tan δ of the polishing layer at 40 ° C.
The fluctuation rate of tan δ of the polishing layer at 20 ° C. to 80 ° C. represented by is 50% or less. That is, in the polishing layer of the polishing pad of the present invention, the value of tan δ at the polishing temperature (around 40 ° C.) is larger than that of the conventional polishing pad, and the temperature change of tan δ is small in a wide temperature range of 20 ° C. to 80 ° C. .. In addition, in this specification, it is expressed as a percentage obtained by multiplying the value of the fluctuation rate by 100.

The viscoelasticity of a material can be considered by combining both a storage elastic modulus (E ″) that reflects elasticity and a loss elastic modulus (E ″) that reflects viscosity. tan δ = loss elastic modulus (E ″) / storage elastic modulus (E ″) is a parameter that reflects the balance between the two. Generally, when tan δ is large, it tends to be rich in viscosity, and when tan δ is small, it tends to be rich in elasticity. The polishing layer of the conventional polyurethane resin tends to have a large tan δ because the viscosity increases as the temperature rises.

However, as a result of diligent studies, the present inventors have found that when the constituent component of the polyurethane resin contains a component derived from PPG, the value of tan δ of the polishing layer at the polishing temperature (around 40 ° C.) is that of the conventional polishing pad. It was found that the temperature change of tan δ of the polishing layer was small in a wide temperature range of 20 ° C. to 80 ° C. This means that the polishing pad of the present invention is highly viscous even in a relatively low temperature of 20 ° C to 40 ° C and is less likely to damage the object to be polished, while it is also in a relatively high temperature of 40 ° C to 80 ° C. This means that the initial polishing rate can be maintained without becoming too viscous. In the industry, it tends to be expected that the polishing rate decreases when the value of tan δ of the polishing layer is high, but in the present invention, since the value of tan δ does not easily change in temperature, the entire process from the beginning to the end of the polishing process. When evaluated over, the unexpected result that the desired polishing rate is obtained with less defects such as scratches can be obtained. This can be understood from the fact that the polishing pad of the present invention exhibits excellent polishing characteristics such as high step performance, few scratches, and a high polishing rate in the results of the polishing test described later.

で表されるＰＴＭＧ（ポリオキシテトラメチレングリコール）は、温度変化に対して分子が変形しやすいが、本発明で、上記プレポリマーのポリオール成分に従来のＰＴＭＧの代わりに下記構造式：

で表されるＰＰＧ（ポリプロピレングリコール）を用いたことにより、温度変化に対して分子が変形しにくい材料を製造できたことによると考えられる。すなわち、ＰＴＭＧ単位は炭素数４個分の長さの直鎖構造であるため、低温領域では凝集しやすい分子構造であり、高温領域になると凝集した分子同士がほつれやすい。一方、本発明でプレポリマーに使用するＰＰＧ単位は炭素数２個分の長さの主鎖を構成し、メチル基が主鎖から分岐しているので、低い温度領域でも凝集しにくい分子構造となっている。このような両者の構造の違いは、温度上昇に伴う分子の運動性にも影響していると考えられる。 Although the action and effect of the present invention have been experimentally found and are not bound by a specific theory, they have been conventionally used as a polyol component used as a prepolymer material in polyurethane resins for hard polishing pads. , The following structural formulas that have been used:

The molecule of PTMG (polyoxytetramethylene glycol) represented by is easily deformed by a temperature change, but in the present invention, the polyol component of the prepolymer is replaced with the following structural formula:

It is considered that the use of PPG (polypropylene glycol) represented by (1) made it possible to produce a material in which the molecules are not easily deformed by temperature changes. That is, since the PTMG unit has a linear structure having a length of four carbon atoms, it has a molecular structure that easily aggregates in the low temperature region, and the aggregated molecules easily fray in the high temperature region. On the other hand, the PPG unit used for the prepolymer in the present invention constitutes a main chain having a length of two carbon atoms, and since the methyl group is branched from the main chain, it has a molecular structure that does not easily aggregate even in a low temperature region. It has become. It is considered that such a difference in structure between the two also affects the motility of the molecule with increasing temperature.

に示す２官能のＰＰＧであることが好ましい。ＰＰＧの数平均分子量は、７００〜５０００であることが好ましく、より好ましくは１０００〜２０００である。数平均分子量が１０００または分子長がＰＴＭＧ１０００と同等のＰＰＧが特に好ましい。 [Prepolymer]
The isocyanate-terminated prepolymer of the present invention contains components derived from toluene diisocyanate (TDI) and polypropylene glycol (PPG), and preferably further contains components derived from diethylene glycol (DEG). TDI is graded according to the ratio of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, TDI100 (2,4-toluene diisocyanate 100%), TDI80 (2,4-toluene diisocyanate 80% and 2,6). -Mixture with 20% toluene diisocyanate) and the like. The PPG may have a substituent as long as it does not affect the performance of the polishing pad of the present invention, but the following structural formula:

It is preferably a bifunctional PPG shown in. The number average molecular weight of PPG is preferably 700 to 5000, more preferably 1000 to 2000. PPG having a number average molecular weight of 1000 or a molecular length equivalent to PTMG1000 is particularly preferable.

The molar ratio of the isocyanate component to the PPG component in the prepolymer is preferably 20: 1 to 2: 1, more preferably 10: 1 to 2: 1. When other third components such as DEG are added, the total amount of the components constituting the prepolymer is set to 100 mol%, and the third component is adjusted to be 30 mol% or less, particularly 5 to 25 mol%. ..

Examples of prepolymers preferably used in the present invention are shown below.
Prepolymer (1): TDI100 (50-90 mol%) / PPG1000 (25-5 mol%) / DEG (25-5 mol%) (NCO equivalent 400-600)
Urethane prepolymer prepolymer (2) having an NCO equivalent of 400 to 600 containing TDI100 (toluene-2,4-diisocyanate) as a polyisocyanate component, PPG1000 (polypropylene glycol having a number average molecular weight of 1000) and DEG (diethylene glycol) as polyol components: TDI100 (50-90 mol%) / PPG1000 (15-3 mol%) / PPG2000 (polypropylene glycol with a number average molecular weight of 2000) (10-2 mol%) / DEG (25-5 mol%) (NCO equivalent 400-600) )
NCO equivalent 400 to include TDI100 (toluene-2,4-diisocyanate) as a polyisocyanate component, PPG1000 (polypropylene glycol with a number average molecular weight of 1000), PPG2000 (polypropylene glycol with a number average molecular weight of 2000) and DEG (diethylene glycol) as a polyol component. 600 urethane prepolymer

[Polishing pad]
The polishing pad of the present invention is formed by laminating a polishing layer made of polyurethane foam resin and a base material layer via a double-sided tape, but depending on the application, there is no base material layer and the polishing layer is directly used as a surface plate of a polishing device. It also includes a mode of pasting on. The polishing layer is arranged at a position in direct contact with the material to be polished.

The polishing pad of the present invention can be used in the same manner as a general polishing pad. For example, the polishing layer can be pressed against the material to be polished while rotating the polishing pad to polish the material to be polished. It can also be polished by pressing it against the polishing layer while rotating it.

[Manufacturing method of polishing pad]
In the polishing pad of the present invention, the polishing layer can be produced by a generally known manufacturing method such as molding or slab molding. First, a polyurethane block is formed by these manufacturing methods, the block is made into a sheet by slicing or the like, a polishing layer formed of a polyurethane resin is formed, and the block is bonded to a base material.

More specifically, the polishing layer has a double-sided tape attached to the surface side opposite to the polishing surface of the polishing layer, attached to the base material layer, cut into a predetermined shape, and the polishing pad of the present invention. Become. The double-sided tape is not particularly limited, and can be arbitrarily selected and used from the double-sided tapes known in the art.

The polishing layer is formed by preparing a polyurethane resin curable composition containing a polyisocyanate compound and a polyol compound and curing the polyurethane resin curable composition. In the present invention, a prepolymer whose performance of the polishing layer can be easily controlled is prepared in advance, and a predetermined curing agent is mixed with the prepolymer to prepare a polyurethane resin curable composition.

The polishing layer is made of a foamed polyurethane resin in which bubbles are dispersed in the polyurethane resin curable composition. The method for forming bubbles is not particularly limited, and there are a method of forming bubbles by mixing a chemical foaming agent, a foam in which mechanical bubbles are mixed, and a method in which fine hollow spheres are mixed. .. From the viewpoint of easy control of the bubble diameter, a method of forming bubbles by mixing minute hollow spheres is preferable. In this case, a polyurethane resin foam-curable composition containing a prepolymer, a curing agent and a foaming agent is prepared, and a foam is formed by curing the polyurethane resin foam-curable composition.

The polyurethane resin curable composition may be, for example, a two-component composition prepared by mixing solution A containing a polyisocyanate compound (prepolymer) and solution B containing other components. The liquid B containing other components can be further divided into a plurality of liquids and mixed with three or more liquids to obtain a composition.

In the present invention, a prepolymer containing the above-mentioned components derived from PPG is used. The NCO equivalent of the prepolymer is preferably 400-600, more preferably 400-550, and even more preferably 450-510. The NCO equivalent is "(mass part of polyisocyanate compound + mass part of polyol compound) / [(number of functional groups per molecule of polyisocyanate compound x mass part of polyisocyanate compound / molecular weight of polyisocyanate compound)-(polyxylate compound). The number of functional groups per molecule of the compound x the mass part of the polyol compound / the molecular weight of the polyol compound)] ”is a numerical value indicating the molecular weight of PP (prepolymer) per NCO group.

[Isocyanate component]
Examples of isocyanate components other than TDI include, for example.
m-Phenylene diisocyanate,
p-phenylene diisocyanate,
Naphthalene-1,4-diisocyanate,
Diphenylmethane-4,4'-diisocyanate (MDI),
4,4'-Methylene-bis (cyclohexyl isocyanate) (hydrogenated MDI),
3,3'-dimethoxy-4,4'-biphenyldiisocyanate,
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-Phenylisothiocyanate,
Xylylene-1,4-diisothiocyanate,
Ethilidine diisothiocyanate and the like can be mentioned.

[Polycarbonate component]
Examples of the polyol component other than PPG (that is, 1,2-propanediol) include, for example.
Ethylene glycol, diethylene glycol, triethylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentandiol, 3-methyl-1,5-pentanediol, 1, Diols such as 6-hexanediol;
Polyether polyols such as polytetramethylene glycol (PTMG), polyethylene glycol, polypropylene glycol;
Polyester polyols such as a reaction product of ethylene glycol and adipic acid and a reaction product of butylene glycol and adipic acid;
Polycarbonate polyol;
Polycaprolactone polyol;
And so on.

[Hardener]
In the present invention, the curing agent consists of polyamines and polyols.
Polyamine hardener:
Examples of polyamines include diamines, which include alkylenediamines such as ethylenediamine, propylenediamine and hexamethylenediamine; diamines having an aliphatic ring such as isophoronediamine and dicyclohexylmethane-4,4'-diamine; 3 , 3'-Dichloro-4,4'-diaminodiphenylmethane (also known as methylenebis-o-chloroaniline) (hereinafter abbreviated as MOCA) and other diamines having an aromatic ring; 2-hydroxyethylethylenediamine, 2-hydroxy Diamines having hydroxyl groups such as ethylpropylene diamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, etc., particularly hydroxyalkylalkylenediamine; Be done. In addition, trifunctional triamine compounds and tetrafunctional or higher functional polyamine compounds can also be used.
Polyol hardener:
Examples include the polyol component exemplified in the above-mentioned item of prepolymer component including PPG.

[Composition and amount of hardener used]
The flexibility of the polishing pad can be adjusted not only by the components of the prepolymer but also by the mixing ratio of the polyamine curing agent and the polyol curing agent. When a mixture of a polyamine curing agent and a polyol curing agent is used, the hydroxyl group ratio of the curing agent, which is the ratio of the number of hydroxyl groups in the curing agent when the number of amino groups in the curing agent is 100, is 10 to 50. It is preferable, and more preferably, the hydroxyl group ratio is 15 to 30. Further, the curing agent has an R value which is an equivalent ratio of active hydrogen groups (amino groups and hydroxyl groups) present in the curing agent to the isocyanate group existing at the end of the prepolymer so as to be 0.60 to 1.2. It is preferable to use the amount. The R value is more preferably 0.70 to 1.0, and even more preferably 0.80 to 0.95. The D hardness of the polishing pad (JISK6253-1997 / ISO7619) is preferably 20 to 70, more preferably 30 to 50.

[Blowing agent]
A foam can be formed by mixing the fine hollow spheres with the polyurethane resin. The microhollow sphere refers to an unexpanded heat-expandable microsphere composed of an outer shell (polymer shell) made of a thermoplastic resin and a low boiling point hydrocarbon contained in the outer shell, which is heated and expanded. .. As the polymer shell, for example, a thermoplastic resin such as an acrylonitrile-vinylidene chloride copolymer, an acrylonitrile-methylmethacrylate copolymer, or a vinyl chloride-ethylene copolymer can be used. Similarly, as the low boiling point hydrocarbon contained in the polymer shell, for example, isobutane, pentane, isopentane, petroleum ether and the like can be used.

The present invention will be specifically described with reference to the following examples, but the following description is not intended to be construed as limiting the scope of the present invention to the following examples.
[material]
The materials used in the following examples are listed.

・ Isocyanate-terminated prepolymer:
The following four types of prepolymers were prepared according to methods common in the art and subjected to the following examples and comparative examples.
Prepolymer (1): TDI100 / PPG1000 / DEG (NCO equivalent 506)
TDI100 (toluene-2,4-diisocyanate) (66.7 mol%) as a polyisocyanate component, PPG1000 (polypropylene glycol having a number average molecular weight of 1000) (20.9 mol%) and DEG (diethylene glycol) (12. Urethane prepolymer with NCO equivalent 506 obtained by reacting 4 mol%) Prepolymer (2): TDI100 / PPG1000 / PPG2000 / DEG (NCO equivalent 505)
TDI100 (toluene-2,4-diisocyanate) (66.7 mol%) as a polyisocyanate component, PPG1000 (polypropylene glycol having a number average molecular weight of 1000) (6.4 mol%), PPG2000 (number average molecular weight 2000) as a polyol component Urethane prepolymer with NCO equivalent 505 obtained by reacting polypropylene glycol) (6.8 mol%) and DEG (diethylene glycol) (20.1 mol%): TDI100 / PTMG650 / DEG (NCO equivalent) 458)
Urethane prepolymer prepolymer (4) having an NCO equivalent of 458 containing TDI100 (toluene-2,4-diisocyanate) as a polyisocyanate component, PTMG650 (polytetramethylene glycol having a number average molecular weight of 650) and DEG (diethylene glycol) as polyol components: TDI100 / PTMG1000 / PTMG650 / DEG (NCO equivalent 458)
Includes TDI100 (toluene-2,4-diisocyanate) as a polyisocyanate component, PTMG1000 (polytetramethylene glycol with a number average molecular weight of 1000), PTMG650 (polytetramethylene glycol with a number average molecular weight of 650) and DEG (diethylene glycol) as polyol components. Urethane prepolymer with NCO equivalent of 458

・ Hardener:
Hardener (1): MOCA (3,3'-dichloro-4,4'-diaminodiphenylmethane, also known as methylenebis-o-chloroaniline)
Hardener (2): 1: 1 mixture of MOCA and PPG2000 (weight ratio)

-Other components Micro hollow sphere (foaming agent): EXPANCEL 551DE40d42 manufactured by Nippon Phillite Co., Ltd.

[Example 1]
100 g of the prepolymer (1) was prepared as the A component, 23 g of the curing agent MOCA was prepared as the B component, and 2 g of the micro hollow spheres were prepared as the C component.
After mixing the A component and the C component and defoaming the mixture of the A component and the C component under reduced pressure, the mixture of the A component and the C component and the B component were supplied to the mixer.
The obtained mixed solution was cast into a mold heated to 80 ° C., heated for 1 hour to cure, and then the formed resin foam was extracted from the mold and then cured at 120 ° C. for 5 hours. This foam was sliced to a thickness of 1.3 mm to prepare a urethane sheet, and the polishing performance was evaluated using this urethane sheet as a polishing pad.

Table 1 shows the composition, R value and D hardness of the obtained urethane sheet. The D hardness was determined as follows.
(D hardness)
The D hardness of the polishing pad was measured using a D-type hardness tester in accordance with the Japanese Industrial Standards (JIS-K-6253). Here, the sample was obtained by stacking a plurality of urethane sheets as needed so that the total thickness was at least 4.5 mm or more.

[Examples 2 to 6 and Comparative Examples 1 to 3]
Based on the formulation shown in Table 1, 5 types of polishing pads using 2 types of prepolymers using PPG were prepared as Examples 2 to 6. Comparative Example 1 is a conventionally known polishing pad IC1000 (manufactured by Nitta Haas). Based on the formulation shown in Table 1, a polishing pad using PTMG prepolymer and MOCA as a curing agent was prepared as Comparative Example 2, and a polishing pad using MOCA and PPG2000 as a curing agent in PTMG prepolymer was prepared as Comparative Example 3, respectively. Table 1 shows the composition, R value and D hardness of the urethane sheets of Examples 2 to 6 and Comparative Examples 1 to 3.

[Dynamic viscoelasticity measurement (DMA)]
For each of the above Examples and Comparative Examples, the viscoelastic properties of the sample by the dynamic viscoelasticity test were the storage elastic modulus (E'), the loss elastic modulus (E "), and the loss tangent: tanδ (= E" / E'. ) Was measured at 20 to 80 ° C. The dynamic viscoelasticity test was measured under the following conditions according to JIS K7244-4.
Measuring device: TA Instruments Japan RSAIII
Test mode: Tension temperature dispersion Test piece: 4 x 0.5 x 0.125 cm
Frequency: 1.6Hz
Initial load: 148g
Temperature: 20-80 ° C
Strain range: 0.1%
Heating rate: 5 ° C./min The DMA measurement results (tan δ) of each Example / Comparative Example are shown in Table 2, FIG. 1 and FIG.

In Table 2, the volatility is defined by the following equation.
[(Maximum value of tan δ at 20 ° C to 80 ° C)-(Minimum value of tan δ at 20 ° C to 80 ° C)] / tan δ at 40 ° C
In Table 2, the fluctuation rate is expressed as a percentage obtained by multiplying the value of the above formula by 100.

As can be seen from Table 2, the conventionally known polishing pad of Comparative Example 1 had a low value of tan δ at 40 ° C. of 0.106, and the fluctuation rate of tan δ was also slightly large. Further, in Comparative Example 2 in which a prepolymer containing PTMG (prepolymer (3)) was used and MOCA and PPG were used as curing agents, the value of tan δ at 40 ° C. was as high as 0.134, but the fluctuation rate of tan δ was high. It has increased to 103.3%. In Comparative Example 3 in which a prepolymer containing PTMG (prepolymer (4)) was used and MOCA was used as a curing agent, the value of tan δ at 40 ° C. was as low as 0.093, and the fluctuation rate of tan δ was also 50.5%. It was a big one. On the other hand, in Examples 1 to 6 using the prepolymers containing PPG (prepolymers (1) and (2)), even if the component ratio of the curing agent was changed, the value of tan δ at 40 ° C. was 0. When it was 12 or more, the fluctuation rate of tan δ was 30% or less.

A polishing test was performed on the polishing pads of the above Examples and Comparative Examples. The results are shown below.
<Conditions for polishing test>
-Grinding machine used: F-REX300X manufactured by Ebara Corporation
・ Disk: 3MA188 (# 100)
-Rotation speed: (Surface plate) 70 rpm, (Top ring) 71 rpm
・ Polishing pressure: 3.5psi
-Abrasive: Made by Cabot Corporation, Part number: SS25 (SS25 stock solution: pure water = 1: 1 weight ratio mixed solution used)
・ Abrasive temperature: 20 ℃
・ Abrasive discharge rate: 200 ml / min
-Work (object to be polished): A substrate formed by PE-CVD with tetraethoxysilane on a 12-inch silicon wafer so that the thickness of the insulating film is 1 μm.-Pad break: 35N 10 minutes-Conditioning: Ex-situ, 35N, 4 scans

(Evaluation of defect performance)
The defect performance was measured by polishing 25 substrates and measuring 5 substrates from the 21st to 25th substrates after polishing in the high-sensitivity measurement mode of a wafer surface inspection device (Surfscan SP1DLS manufactured by KLA Tencor). The number of defects such as scratches on the surface of the substrate was counted. The defects evaluated here are the total of defects such as particles, organic substances thought to be derived from pad scraps, organic residues, scratches, voids derived from the film, and watermarks.
The evaluation criteria for defect performance are as follows.
Less than 50 defects of 0.16 μm or more: ◎ (extremely good)
Less than 100 defects of 0.16 μm or more: ○ (good)
Number of defects of 0.16 μm or more and less than 200: △ (slightly good)
Number of defects of 0.16 μm or more 200 or more: × (defective)

(Evaluation of step performance)
For the step performance, a wafer with a copper wiring pattern (754 wafer manufactured by SEMATECH) is used, polished with an abrasive (manufactured by Fujimi Corporation, PLANARLITE7000), and 100 μm / 100 μm dishing is performed with a step / surface roughness / fine shape measuring device. It was evaluated by measuring with (KLA Tencor Co., Ltd., P-16 +).
The evaluation criteria for step performance are as follows, evaluated based on the depth of the depression from the insulating film.
Dishing less than 400 Å: ◎ (extremely good)
Dishes less than 500 Å: ○ (good)
Dishing is 750 Å or more: × (bad)

The evaluation results of the defect performance and the step performance are shown in Table 3 below.

From the results in Table 3, the defect performance was poor in all of Comparative Examples 1 to 3, while the number of defects was less than 200 in all of Examples 1 to 6. It is considered that the variation rate of tan δ and the D hardness have an influence on the defect performance. In Examples 1 to 6 in which the variation rate of tan δ is less than 30%, the number of defects is small, and the variation rate of tan δ is 20%. Examples 3-6, which are less than and smaller, gave better results. It is considered that the value of tan δ at 40 ° C. has an influence on the step performance, and Examples 1 to 6 and Comparative Example 2 having a value larger than 0.12 have a good dishing of less than 500 Å, and further from 0.17. The large Examples 1 to 3 and Example 6 gave very good results.

Claims (5)

A polishing pad having a polishing layer made of a polyurethane resin foam.
The polyurethane resin is a cured product of a curable resin composition containing an isocyanate-terminated urethane prepolymer and a curing agent.
The isocyanate-terminated prepolymer contains components derived from toluene diisocyanate (TDI) and polypropylene glycol (PPG).
The value of tan δ of the polishing layer measured by the dynamic viscoelasticity test at a measurement frequency of 10 radians / second and the tensile mode is 0.12 or more at 40 ° C. and the following formula:
[(Maximum value of tan δ of the polishing layer at 20 ° C. to 80 ° C.)-(Minimum value of tan δ of the polishing layer at 20 ° C. to 80 ° C.)] / tan δ of the polishing layer at 40 ° C.
A polishing pad having a fluctuation rate of tan δ of the polishing layer at 20 ° C. to 80 ° C. represented by 50% or less. The polishing pad according to claim 1, wherein the curable resin composition further contains microhollow spheres as a foaming agent. The polishing pad according to claim 1 or 2, wherein the isocyanate-terminated prepolymer further contains a component derived from diethylene glycol (DEG). A method for polishing the surface of an optical material or a semiconductor material, which comprises using the polishing pad according to any one of claims 1 to 3. A method for reducing scratches when polishing the surface of an optical material or a semiconductor material by using the polishing pad according to any one of claims 1 to 3.

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