JP7123722B2 - polishing pad - Google Patents

Description

The present invention relates to polishing pads. The polishing pad of the present invention is used for polishing optical materials, semiconductor wafers, semiconductor devices, 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 for

In recent years, semiconductors have become highly integrated and ultra-miniaturized, and the wiring width of circuits is becoming smaller year by year. When a plurality of wirings having different wiring widths are provided on the same substrate, it is important to handle different steps for each wiring width that occur during manufacturing. Patent Literature 1 discloses a polishing pad with improved local residual step characteristics and large-scale residual step characteristics by increasing the thickness of the foamed polyurethane portion, which is the polishing layer, compared to the nonwoven fabric portion, which is the base layer. ing.

Japanese Patent Application Laid-Open No. 2001-332519

However, while there are cases where it is required to eliminate the step regardless of the wiring width, there are cases where different step performance is required depending on the wiring width. As integrated circuits become more three-dimensional and highly layered, there is a need to eliminate steps near wiring while maintaining the undulations of the layering process. For example, when the wiring width is set to 1 μm or less, the step performance of the wiring width of 1 μm or less is eliminated, and the wiring of 1 μm or more requires performance to maintain the step. SUMMARY OF THE INVENTION An object of the present invention is to provide a polishing pad that eliminates a step in a narrow wiring of 1 μm or less and maintains a step in a wide wiring of more than 1 μm.

According to the present invention, the following are provided.
[1]
A polishing pad having a polishing layer for polishing an object to be polished,
The polishing layer has a polyurethane resin and hollow microspheres dispersed in the polyurethane resin,
The polyurethane resin is a reaction product of a prepolymer containing an isocyanate component and a curing agent,
the curing agent comprises a polyamine and a polyol;
The hydroxyl group ratio of the curing agent is 10 to 50, where the hydroxyl group ratio 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.
The hollow microspheres have an average bubble diameter of less than 20 μm,
A polishing pad characterized by:
[2]
The polishing pad according to [1], wherein the hydroxyl group ratio is 15-30.
[3]
The polishing pad of [1] or [2], wherein the polyamine is 3,3'-dichloro-4,4'-diaminodiphenylmethane, and the polyol is polytetramethylene glycol or polypropylene glycol.
[4]
The polishing pad according to any one of [1] to [3], wherein the prepolymer is prepared by reacting a polyisocyanate compound and a polyol compound.
[5]
The polishing pad according to any one of [1] to [4], wherein the prepolymer has an NCO equivalent of 400-550.

According to the present invention, it is possible to provide a polishing pad capable of achieving different step performance depending on the wiring width.

FIG. 4 is a diagram for explaining steps in circuit boards having different wiring widths (before polishing); FIG. 10 is a diagram for explaining steps in circuit boards having different wiring widths (after polishing); 4 is a graph showing the relationship between the line width (horizontal axis) and the step (vertical axis) in the circuit board after the polishing test in Examples and Comparative Examples.

(action)
The effects of the present invention will be described with reference to FIGS. 1 and 2 showing cross sections of circuit boards having different wiring widths.
A damascene process is adopted as a method of manufacturing metal (Cu) wiring in a semiconductor manufacturing process. This damascene process is performed by digging trenches in an insulating film, filling the trenches with metal by sputtering or the like, and removing excess metal by chemical mechanical polishing (CMP). In order to eliminate the physical or chemical stress generated between the insulating film and the metal, the insulating film is usually covered with a barrier metal before the metal is embedded.
As shown in FIG. 1, when a metal film is embedded, the width and depth of the groove between the portion where the groove exists and the portion where the groove does not exist depends on the width of the groove existing under the metal film. A step occurs. Such steps are classified into small steps to be removed (Dt in FIG. 1) and large steps to be maintained (Df in FIG. 1) during CMP. More specifically, as shown in FIG. 2 showing the cross section of the circuit after polishing, the present invention is aimed at polishing when wirings having different wiring widths (thick wirings and narrow wirings) coexist. , the step of narrow wiring (1 μm or less) is eliminated and the step of wide wiring (greater than 1 μm) is maintained as much as possible.

A feature of the polishing pad of the present invention is that it has a polishing layer for polishing an object to be polished, the polishing layer having a polyurethane resin and hollow microspheres as a foaming agent dispersed in the polyurethane resin. The polyurethane resin is a reaction product of a prepolymer containing an isocyanate component and a curing agent, and the curing agent has a cell diameter of less than 20 μm in a polishing pad made of polyamine and polyol, thereby smoothing out steps in narrow wiring. By setting the hydroxyl group ratio, which is the ratio of the number of hydroxyl groups in the curing agent to 100 amino groups in the curing agent, to 10 to 50, the step of the wide wiring can be maintained. Based on the discovery of new knowledge that

To further explain the characteristics of the polishing pad of the present invention, when the bubble diameter of the micro hollow spheres is less than 20 μm, the surface containing the predetermined bubbles of the polishing pad comes into contact with the steps of the narrow wiring so as to conform to the steps of the narrow wiring. This is considered to be chemically and physically optimal conditions with a polishing agent that is easier to polish the stepped portion of the narrow wiring than the stepped portion of the wiring. On the other hand, when the hydroxyl group ratio of the curing agent is 10 to 50, a relatively flexible polishing pad can be obtained, and the surface of the polishing pad appropriately wraps around the edge of the step of the wide wiring and adheres closely to the step of the narrow wiring. easier to do. In this way, the present invention can be achieved by combining the optimal conditions for maintaining the proper positional relationship with respect to the steps of the wide and narrow wirings by the flexible surface of the polishing pad and the polishing of the steps of the narrow wirings by appropriately sized air bubbles. In the invention, the step (low step) of the narrow wiring can be selectively polished while maintaining the step (high step) of the wide wiring. Normally, the polishing action is to polish from the higher steps, and finally the lower steps are polished to produce a flat surface as a whole. The effect of the present invention that still remains is completely unexpected for those skilled in the art.

(polishing pad)
The polishing pad of the present invention comprises a polishing layer made of foamed polyurethane resin and a substrate layer laminated via a double-sided tape. Also includes a mode of attaching to. 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. It is also possible to polish by pressing against the polishing layer while rotating.

(Method for manufacturing polishing pad)
In the polishing pad of the present invention, the polishing layer can be produced by generally known manufacturing methods such as molding and slab molding. First, a block of polyurethane is formed by these manufacturing methods, the block is made into a sheet by slicing or the like, a polishing layer formed from a polyurethane resin is molded, and the polishing layer is laminated to a base material.

More specifically, the polishing layer is attached with a double-sided tape to the surface opposite to the polishing surface of the polishing layer, attached to the base material layer, and cut into a predetermined shape to form the polishing pad of the present invention. Become. The double-sided tape is not particularly limited, and can be used by arbitrarily selecting from 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 curable polyurethane resin composition is prepared by preparing in advance a prepolymer that facilitates control of the performance of the polishing layer and mixing it with a predetermined curing agent.

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

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

In the present invention, a prepolymer containing isocyanate groups is employed as the polyisocyanate compound in order to accurately control the physical properties of the polyurethane foam. should be included. Prepolymers commonly used in the art containing unreacted isocyanate groups can also be used in the present invention. The NCO equivalent weight of the prepolymer is preferably 400-550, more preferably 450-500. If the NCO equivalent is too high, the step performance of fine wiring tends to be deteriorated, and if it is too low, wide undulation tends to be easily eliminated. The NCO equivalent is "(mass part of polyisocyanate compound + mass part of polyol compound) / [(number of functional groups per molecule of polyisocyanate compound × mass part of polyisocyanate compound / molecular weight of polyisocyanate compound) - (polyol The number of functional groups per molecule of the compound×parts by mass of the polyol compound/molecular weight of the polyol compound)]”, and is a numerical value indicating the molecular weight of PP (prepolymer) per NCO group.

(isocyanate component)
Examples of isocyanate components include
m-phenylene diisocyanate,
p-phenylene diisocyanate,
2,6-tolylene diisocyanate (2,6-TDI),
2,4-tolylene diisocyanate (2,4-TDI),
naphthalene-1,4-diisocyanate,
diphenylmethane-4,4'-diisocyanate (MDI),
4,4′-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI),
3,3′-dimethoxy-4,4′-biphenyl diisocyanate,
3,3′-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,
and ethylidine diisothiocyanate.

(Polyol component)
Examples of polyol components 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, diols such as 5-pentanediol and 1,6-hexanediol;
Polyether polyols such as polytetramethylene glycol (PTMG), polyethylene glycol, polypropylene glycol;
Polyester polyols such as reaction products of ethylene glycol and adipic acid and reaction products of butylene glycol and adipic acid;
polycarbonate polyols;
polycaprolactone polyol;
etc.

(curing agent)
In the present invention, the curing agent consists of polyamines and polyols.
Polyamine curing agent:
Polyamines include, for example, diamines, including alkylenediamines such as ethylenediamine, propylenediamine and hexamethylenediamine; diamines having an aliphatic ring such as isophoronediamine and dicyclohexylmethane-4,4′-diamine; ,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 a hydroxyl group such as ethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, especially hydroxyalkylalkylenediamine; be done. Tri-functional triamine compounds and tetra- or higher-functional polyamine compounds can also be used.
Polyol curing agent:
The polyol components exemplified in the item of the components of the prepolymer described above can be used.

(Composition and usage amount of curing agent)
The flexibility of the polishing pad can be adjusted by adjusting the mixing ratio of the polyamine curing agent and the polyol curing agent. 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 assumed to be 100, is required to exhibit the effects of the present invention. , preferably the hydroxyl group ratio is 15-30. In addition, the R value, which is the equivalent ratio of the active hydrogen groups (amino groups and hydroxyl groups) present in the curing agent to the isocyanate groups present at the ends of the prepolymer, is 0.60 to 1.40. It is preferred to use quantities. The R value is more preferably 0.70 to 1.20, even more preferably 0.80 to 1.10. The D hardness (JISK6253-1997/ISO7619) of the polishing pad is preferably 20-70, more preferably 30-50.

(foaming agent)
A foam can be formed by mixing hollow microspheres into a polyurethane resin. Hollow microspheres are heat-expanded unfoamed heat-expandable microspheres composed of an outer shell (polymer shell) made of a thermoplastic resin and a low-boiling-point hydrocarbon contained in the outer shell. . Thermoplastic resins such as acrylonitrile-vinylidene chloride copolymer, acrylonitrile-methyl methacrylate copolymer, and vinyl chloride-ethylene copolymer can be used as the polymer shell. Similarly, as the low boiling point hydrocarbon encapsulated in the polymer shell, for example, isobutane, pentane, isopentane, petroleum ether and the like can be used.

Hollow microspheres can also be used as commercially available products. For example, the Matsumoto Microsphere series (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) and the Expancel series (manufactured by AkzoNobel) can be used as micro hollow spheres. Commercially available hollow microspheres include an expanded type that has already been heated and expanded and an unexpanded type that has not yet been heated and expanded. The expanded type is largely unaffected by the heat of reaction generated in the mixing step described later and can have a constant cell diameter, while the unexpanded type expands due to the heat of reaction generated in the mixing step described later. Therefore, in the case of the unexpanded type, in order to control the cell diameter, for example, the reaction heat generated by the polymerization reaction must be rapidly cooled, or the polymerization reaction can be rapidly promoted, and the resin existing around the micro hollow spheres It is necessary to adjust the reaction conditions such that the expansion is forcibly suppressed by

In the present invention, it is necessary for the hollow microspheres to have an average bubble diameter of less than 20 μm in order to achieve the effects of the present invention. If the bubble diameter in the resin is to be less than 20 μm, it is necessary to use unexpanded hollow microspheres with an average particle diameter of 10 to 20 μm and adjust the reaction conditions so that the hollow microspheres do not expand too much. . The unexpanded type hollow microspheres preferably have an average particle diameter of 10 to 20 μm, and the average bubble diameter of the air bubbles dispersed in the polyurethane resin of the polishing layer after each step described below is 10 to 20 μm. preferably 12 to 20 μm, more preferably 15 to 20 μm. The average bubble diameter of the hollow microspheres in the polishing pad can be measured using a laser microscope or CT scan.

The present invention will be experimentally illustrated by the following examples, but the following descriptions are not intended to be construed as limiting the scope of the present invention to the following examples.
<Example 1>
100 parts of an isocyanate group-terminated urethane prepolymer having an NCO equivalent of 500 obtained by reacting 2,4-tolylene diisocyanate (TDI), poly(oxytetramethylene) glycol (PTMG) and diethylene glycol (DEG), and the shell portion is acrylonitrile- 4 parts of unexpanded hollow microspheres made of a vinylidene chloride copolymer and containing isobutane gas in the shell were added and mixed to obtain a mixed liquid. The obtained mixture was charged into the first liquid tank and kept at 80°C. Next, separately from the first liquid, 19 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) and 19 parts of polyoxytetramethylene glycol (PTMG) having an average molecular weight of 1000 are added as curing agents. They were mixed (hydroxyl group ratio: 26.7) and kept at 120°C in the second liquid tank. The liquids of the first liquid tank and the second liquid tank were poured into a mixer equipped with two injection ports from each injection port, and the equivalent ratio of the amino groups and hydroxyl groups present in the curing agent to the terminal isocyanate groups in the prepolymer. was injected so that the R value representing the was 0.90. After the injected two liquids were mixed and stirred, they were poured into a mold of a molding machine preheated to 100° C., the mold was closed, and the mixture was heated at 110° C. for 30 minutes for primary curing. After the primary cured molded product was removed from the mold, it was secondary cured in an oven at 130° C. for 2 hours to obtain a urethane resin molded product. The obtained urethane resin molding was allowed to cool to 25° C., heated again in an oven at 120° C. for 5 hours, and then sliced into 1.3 mm thick pieces to obtain polishing pads. The resulting polishing pad had a D hardness of 34 and an average cell diameter of 14.9 μm.

<Example 2>
20.4 parts of 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA) and 13 parts of polyoxytetramethylene glycol (PTMG) having an average molecular weight of 1000 were added to the first liquid used in Example 1 as a curing agent. A polishing pad was obtained in the same manner as in Example 1, except that 6 parts of the compound was added and mixed (hydroxyl group ratio: 17.8). The resulting polishing pad had a D hardness of 47 and an average cell diameter of 15.5 μm.

<Example 3>
The isocyanate group-terminated urethane prepolymer used in Example 1 was reacted with 2,4-tolylene diisocyanate (TDI), poly(oxytetramethylene) glycol (PTMG) and diethylene glycol (DEG) to give an NCO equivalent of 460, and cured. As an agent, 21 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) and 21 parts of polyoxytetramethylene glycol (PTMG) having an average molecular weight of 1000 were added and mixed (hydroxyl group ratio: 26.7). A polishing pad was obtained in the same manner as in Example 1 except that it was used. The resulting polishing pad had a D hardness of 40 and an average cell diameter of 16.4 μm.

<Comparative Example 1>
An "IC1000" polishing pad manufactured by Nitta Haas was prepared. The D hardness was 55 and the average cell diameter was 40 μm.

<Comparative Example 2>
The isocyanate group-terminated urethane prepolymer used in Example 1 was reacted with 2,4-tolylene diisocyanate (TDI), poly(oxytetramethylene) glycol (PTMG) and diethylene glycol (DEG) to give an NCO equivalent of 460, and 2 parts of 4,4'-methylene-bis(cyclohexyl isocyanate) (hydrogenated MDI) are mixed, and 28 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA) as a curing agent (hydroxyl group ratio is 0 ) was used, and a polishing pad was obtained in the same manner as in Example 1. The resulting polishing pad had a D hardness of 59 and an average cell diameter of 16.3 μm.

<Comparative Example 3>
Instead of the unexpanded type of hollow microspheres used in Example 1, 3 parts of the expanded type expanded to a particle size of 40 μm were used, and 3,3′-dichloro-4,4′-diaminodiphenylmethane was used as a curing agent. (MOCA) 20.4 parts and polyoxytetramethylene glycol (PTMG) 13.6 parts with an average molecular weight of 1000 were added and mixed (hydroxyl group ratio is 17.8).The same method as in Example 1 was used. to obtain a polishing pad. The resulting polishing pad had a D hardness of 35 and an average cell diameter of 40 μm.

<Comparative Example 4>
Instead of the unexpanded type of hollow microspheres used in Example 1, 3 parts of the expanded type expanded to a particle size of 40 μm were used, and 3,3′-dichloro-4,4′-diaminodiphenylmethane was used as a curing agent. 21 parts of (MOCA) and 7 parts of polyoxytetramethylene glycol (PTMG) having an average molecular weight of 1000 were added and mixed (hydroxyl group ratio was 8.9). A polishing pad was obtained. The resulting polishing pad had a D hardness of 50 and an average cell diameter of 40 μm.

(Test method)
(D hardness)
D hardness was measured according to JISK6253-1997/ISO7619.

(Evaluation of step performance)
A pattern wafer having wirings with different wiring widths (wiring widths: 0.3 μm, 1 μm, 2 μm, 8 μm, 40 μm) coexisting was prepared, and the polishing pads prepared in Examples and Comparative Examples were thin wirings (1 μm or less). It was evaluated whether or not it is possible to eliminate the step difference and maintain the step difference of the wide wiring (larger than 1 μm) as much as possible. The step performance of narrow wiring is indicated by ◯ when the step is less than 20 nm, Δ when the step is between 20 and 40 nm, and x when the step is greater than 40 nm. The step performance of the wide wiring is indicated by ◯ when the step is 80 nm or more, Δ when the step is 50 to 80 nm, and x when the step is less than 50 nm. Polishing conditions are as follows.
Polishing machine: F-REX300 (manufactured by Ebara Corporation)
Disk: A188 (manufactured by 3M)
Rotation speed: (surface plate) 70 rpm, (top ring) 71 rpm
Polishing pressure: 3.5 psi
Abrasive temperature: 20°C
Abrasive discharge rate: 200ml/min
Abrasive: PLANERLITE7000 (manufactured by Fujimi Corporation)
Object to be polished: above pattern wafer Polishing time: 60 seconds Pad break: 35N 10 minutes Conditioning: Ex-situ, 35N, 4 scans

Table 1 shows the test results of each example and comparative example, and FIG.

From the results of Examples 1 to 3, when the average bubble diameter of the hollow microspheres is set to less than 20 μm and the hydroxyl group ratio of the curing agent is set to 10 to 50, the step of the narrow wiring is eliminated and the step of the wide wiring is maintained. I found out. According to Comparative Example 1 (commercially available polishing pad), which does not satisfy the requirements of the present invention, although the step of the narrow wiring is polished (evaluation: ○), the step of the wide wiring is also polished (evaluation: ×). , it was found that the effect of the present invention cannot be obtained. In Comparative Example 2, in which the average bubble diameter satisfies the requirements of the present invention but the hydroxyl group ratio does not satisfy the requirements of the present invention, although the step of the wide wiring is maintained (evaluation: ◯), the step of the narrow wiring is also maintained. Unfortunately (evaluation: Δ), it was found that the effects of the present invention could not be obtained. In Comparative Example 3, in which the hydroxyl group ratio satisfies the requirements of the present invention but the average bubble diameter does not satisfy the requirements of the present invention, the step of the narrow wiring was eliminated (evaluation: ○), but the step of the wide wiring was polished. (Evaluation: Δ), and it was found that the effects of the present invention could not be obtained. In Comparative Example 4, in which neither the average cell diameter nor the hydroxyl group ratio satisfied the requirements of the present invention, the step of the narrow wiring was maintained (evaluation: △), and the step of the wide wiring was polished (evaluation: △). It turned out that the effect of the invention could not be exhibited. The above test results are also shown in FIG. In this way, the present invention can be achieved by combining the optimum conditions for maintaining the appropriate positional relationship with respect to the steps of the wide and narrow wirings by the flexible surface of the polishing pad and the polishing of the steps of the narrow wirings by appropriately sized air bubbles. In the present invention, the steps (low steps) of narrow wires can be selectively polished while maintaining the steps (high steps) of wide wires. Normally, the polishing action is to polish the higher steps first, and finally the lower steps are polished to produce a flat surface as a whole. The effect of the present invention that still remains is completely unexpected for those skilled in the art.

Claims (7)

A polishing pad having a polishing layer for polishing an object to be polished,
The polishing layer has a polyurethane resin and hollow microspheres dispersed in the polyurethane resin,
The polyurethane resin is a reaction product of a prepolymer containing an isocyanate component and a curing agent,
the curing agent comprises a polyamine and a polyol;
The hydroxyl group ratio of the curing agent is 10 to 26.7 , where the hydroxyl group ratio 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.
The hollow microspheres have an average bubble diameter of 12 μm or more and less than 20 μm,
A polishing pad characterized by: 2. The polishing pad according to claim 1, wherein said hydroxyl group ratio is 15 to 26.7 . 3. The polishing pad of claim 1 or 2, wherein said polyamine is 3,3'-dichloro-4,4'-diaminodiphenylmethane and said polyol is polytetramethylene glycol or polypropylene glycol. The polishing pad according to any one of claims 1 to 3, wherein the prepolymer is prepared by reacting a polyisocyanate compound and a polyol compound. The polishing pad according to any one of claims 1 to 4, wherein the prepolymer has an NCO equivalent weight of 400-550. 6. The polishing pad according to any one of claims 1 to 5, which is used for polishing a circuit board having narrow wirings of 1 μm or less and wide wirings of more than 1 μm formed by a damascene process. A polishing pad having a polishing layer for polishing an object to be polished,
The polishing layer has a polyurethane resin and hollow microspheres dispersed in the polyurethane resin,
The polyurethane resin is a reaction product of a prepolymer containing an isocyanate component and a curing agent,
the curing agent comprises a polyamine and a polyol;
The hydroxyl group ratio of the curing agent is 10 to 50, where the hydroxyl group ratio 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.
The hollow microspheres have an average bubble diameter of less than 20 μm,
A polishing pad for polishing a circuit board having narrow wirings of 1 μm or less and wide wirings of more than 1 μm formed by a damascene process .

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