JP7442275B2 - polishing pad - Google Patents

Description

The present invention relates to a polishing pad and a method for manufacturing the same. Specifically, the present invention relates to a polishing pad that can be used for polishing optical glass, semiconductor wafers, semiconductor devices, hard disk substrates, plastic lenses, and the like.

Semiconductor devices and the like are generally polished by a so-called chemical mechanical polishing (CMP) method. The CMP method is a polishing method that can obtain a smooth polished surface at high speed, and has a mechanical polishing (surface removal) effect due to the relative movement of the polishing material and the polishing object due to the action of chemical components contained in the polishing slurry. can be increased.

In the CMP method, the polishing characteristics of the object to be polished vary greatly depending on the holding power of the polishing slurry, so a polishing pad with an excellent ability to hold the polishing slurry is required.

Typically, a new polishing pad undergoes a dressing process to increase its ability to hold polishing slurry, and repeats dummy polishing to improve the polishing properties of the polishing pad, before polishing the actual product.

By the way, among polishing pads, polishing pads that are non-foamed or have a high-density polishing layer with a density of 0.9 to 1.2 g/cm ³ are in demand from the viewpoint of improving the flatness of the object to be polished. Such a polishing layer has a problem in that the entire polishing layer is extremely homogeneous and the polished surface tends to become smooth over time. Furthermore, non-foamed polishing layers are generally made of hard resin and have low brittleness, so it takes time to regenerate the polished surface by dressing treatment.

For the purpose of improving polishing properties, attempts have been made to form a polishing layer into a specific structure using resin phase separation.
Patent Document 1 discloses a polishing cloth having a surface portion formed by phase separation of constituent resins. Patent Document 2 discloses a polishing pad having a phase-separated structure made of two types of prepolymers. Patent Document 3 discloses a porous polishing pad that is phase-separated by using a plurality of curing agents having different curing rates.

Japanese Patent Application Publication No. 8-11050 Japanese Patent Publication No. 5634903 Japanese Patent Application Publication No. 2017-136662

The polishing layers formed by phase separation described in Patent Documents 1 to 3 all have a shape of a so-called sea-island structure consisting of a sea part and an island part. In the case of a sea-island structure, there is a problem that the island portions may fall off in chunks, and the fallen chunks may cause scratches on the object to be polished.

In view of the above-mentioned problems, the present invention makes it possible to reduce the need for dressing treatment even when the polishing layer is non-foamed or has a density of 0.9 to 1.2 g/cm ³ and suppresses smoothing of the polished surface. It is an object of the present invention to provide a polishing pad having a polishing layer having a structure in which island portions are difficult to fall off in chunks.

As a result of intensive research, the present inventors discovered that a polishing pad having a polishing layer phase-separated in a gyroid structure can solve the above problems, and have arrived at the present invention. That is, the present invention includes the following.

[1] A polishing pad in which the cured resin constituting the polishing layer is phase-separated in a gyroid structure,
The polishing pad, wherein at least one of the phase-separated cured resins is selected from the group consisting of polyurethane resins, polyurea resins, and polyurethane polyurea resins.
[2] The polishing pad according to [1], wherein all of the cured resins constituting the polishing layer are selected from the group consisting of polyurethane resins, polyurea resins, and polyurethane polyurea resins.
[3] The polishing pad according to [1] or [2], wherein the polishing layer has a density of 0.9 to 1.2 g/cm ³ .
[4] A method for manufacturing the polishing layer of the polishing pad according to any one of [1] to [3], comprising:
A step of preparing one or more types of polyisocyanate compounds and/or urethane prepolymers;
A step of preparing one or more types of curing agent (however, if the polyisocyanate compound and/or urethane prepolymer is one type, the number of curing agents is two or more types);
A method comprising the step of curing the polyisocyanate compound and/or urethane prepolymer by mixing the polyisocyanate compound and/or urethane prepolymer and the curing agent.
[5] The resin obtained by curing the polyisocyanate compound and/or urethane prepolymer is a polyurethane polyurea resin,
The curing agent is two or more types of curing agents selected from polyol compounds and polyamine compounds,
The active hydrogen equivalent of one of the curing agents is 2.5 times or more of the NCO equivalent of at least one of the polyisocyanate compound and/or urethane prepolymer, and the equivalent of the other curing agent is 2.5 times or more The method according to [4], wherein the active hydrogen equivalent is 0.5 times or less the NCO equivalent of at least one type of the polyisocyanate compound and/or urethane prepolymer.

The polishing pad of the present invention can reduce the dressing process and suppress smoothing of the polishing surface even if it is a non-foamed or high-density polishing layer with a density of 0.9 to 1.2 g/ ^cm3 . It is an object of the present invention to provide a polishing pad having a polishing layer having a structure in which island portions are difficult to fall off in chunks. Since the polishing layer of the polishing pad of the present invention is phase-separated in a gyroid structure, it has a feature that it can form irregularities on the surface with a fine structure and easily retains slurry.

FIG. 1 is a perspective view of an example of a polishing pad of the present invention. FIG. 2 is a SEM image of the polishing pad of Example 1. FIG. 3 is a SEM image of the polishing pad of Example 2. FIG. 4 is a SEM image of the polishing pad of Example 3. FIG. 5 is a SEM image of the polishing pad of Comparative Example 1.

The present invention will be described below, but the present invention is not limited to the specific forms and examples illustrated.

<<Polishing pad>>
The structure of the polishing pad of the present invention will be explained using FIG. 1. As shown in FIG. 1, the polishing pad 1 includes a polishing layer 2, which is a layer that contacts the object to be polished and performs polishing. The polishing layer 2 has a polishing surface 2a that comes into contact with the object to be polished. The shape of the polishing layer 2 of the polishing pad 1 of the present invention is not particularly limited. Examples of the shape include a circular shape and a band-like shape, but a circular shape is preferable.
The size (diameter) of the polishing pad 1 can be determined depending on the size of the polishing apparatus equipped with the polishing pad 1, and can be, for example, about 10 cm to 2 m in diameter.
The thickness of the polishing layer 2 is preferably 0.1 mm to 10 mm, more preferably 0.3 mm to 5 mm.

In the polishing pad 1, the polishing layer 2 may be bonded to the cushion layer 4 via an adhesive layer 3. The adhesive layer 3 is a layer for adhering the cushion layer 4 and the polishing layer 2, and is usually made of double-sided tape or adhesive.

The cushion layer 4 is a layer that makes contact of the polishing layer 2 with the object to be polished more uniform, and can be provided as necessary. The cushion layer 4 can be made of a flexible material such as nonwoven fabric or synthetic resin.

The polishing pad 1 is attached to a polishing device using a known fixing means such as an adhesive tape, an adhesive, or a hook-and-loop fastener. The polishing pad 1 is rotated while being pressed against the object to be polished by a polishing device, and polishes the object to be polished. At that time, slurry is supplied between the polishing pad 1 and the object to be polished. Slurry is supplied to and discharged from the polishing surface through grooves or holes.

<Polishing layer>
There are four types of phase separation structures of block copolymers: lamella (layered), gyroid (mesh), cylinder (cylindrical), and sphere (sea-island structure consisting of independent islands and continuous sea areas). As is known, the polishing layer 2 of the present invention has a phase-separated structure in the form of a gyroid structure. In this specification, the gyroid structure refers to a polishing layer as shown in the photographs shown in FIGS. This refers to a structure in which the cured resin constituting the resin undergoes phase separation in a finely intricate three-dimensional network structure. In FIG. 2, the composition of the polymers is different between the part A and the part B, and it is thought that these different polymers are in the form of a block copolymer in which these different polymers are covalently bonded in a three-dimensional network structure. By forming such a structure, not only ease of dressing and suppression of smoothing can be obtained, but also it is possible to suppress part of the polishing layer 2 from falling off in chunks.

The width of the net portion constituting the gyroid structure (for example, the width indicated by X for resin B in FIG. 2; the same applies to resin A) is preferably about 1 to 200 μm, more preferably 3 to 150 μm. The thickness is more preferably 5 to 100 μm, particularly preferably 5 to 50 μm.

The polishing layer 2 has a structure in which the constituent cured resin is phase-separated into two or more types. The phase-separated resins are not particularly limited as long as they are two or more types, but preferably two, three, or four types. At least one of the two or more separated resins is polyurethane resin, polyurea resin, or polyurethane polyurea resin, but all of the resins used are polyurethane resin, polyurea resin, or polyurethane polyurea resin. Preferably. In this specification, if they are phase separated, they are different types of materials even if they are both polyurethane resins. The same applies to polyurea resins and polyurethane polyurea resins. Therefore, by using one type of polyisocyanate compound or urethane prepolymer used as a raw material for the cured resin and using multiple curing agents, the resin obtained by curing becomes two or more types, and the two or more types of resin are used in the polishing layer. 2, this may also be included in the aspect of the present invention. Phase separation in a gyroid structure can be confirmed by observing an enlarged surface image of a cut surface using an SEM or the like, showing an irregular network structure in which two or more types of phase-separated resins are intertwined with each other.

The polyurethane resin, polyurea resin, or polyurethane polyurea resin that constitutes the polishing layer 2 may be modified with a functional group such as an epoxy group by a known method.

Resins other than polyurethane resins, polyurea resins, and polyurethane polyurea resins that can be used in the polishing layer 2 are not particularly limited as long as they do not impair the effects of the present invention. Examples include epoxy resin, polyolefin, polyvinyl chloride, polycarbonate, fluororesin, silicone resin, and the like.

The gyroid structure of the polishing layer 2 of the polishing pad of the present invention includes those in which foam (or hollow microspheres) are dispersed in the polishing layer 2, and those that do not contain such foam (non-foamed type). However, the polishing layer 2 can be used for any of the following: one in which the polishing layer 2 does not substantially contain foam (non-foamed type) or a high-density type in which the density is 0.9 to 1.2 g/cm ³ These are preferred in that they can fully exhibit the characteristics of the present invention. Here, "substantially does not contain foam" means that it does not intentionally contain foam, and if foam cannot be excluded or is unavoidably included, "foam is not included". "substantially free of".

The polishing layer 2 of the polishing pad 1 of the present invention may or may not contain abrasive grains (filler). When it is included, it is preferably included in an amount of about 1 to 40% by mass, and more preferably about 1 to 20% by mass, based on the total mass of the polishing layer 2, from the standpoint of fully exhibiting the characteristics of the present invention. Abrasive grain materials include cerium oxide, zirconium oxide, zirconium silicate, cubic boron nitride (CBN), ferric oxide, manganese oxide, chromium oxide, silicon dioxide, alumina, barium carbonate, magnesium oxide, calcium carbonate, carbonate. Examples include barium, magnesium oxide, mica, and the like.

Note that the hardness of the polishing layer 2 of the resulting polishing pad 1 is not particularly limited. For example, it can have a hardness of 30 or more Shore A hardness and 95 or less Shore D hardness. Preferably, the Shore A hardness is 50 or more and the Shore D hardness is 90 or less.

<Polished surface>
Polishing layer 2 has a polishing surface 2a. Since the polishing layer 2 uses a material having a gyroid structure, the gyroid structure is exposed on the polishing surface 2a.
Incidentally, the polished surface 2a can be provided with grooves as necessary by surface processing. The grooves may include lattice grooves, concentric grooves, radial grooves, spiral grooves, and combinations thereof.

<<Manufacturing method of polishing pad>>
A method for manufacturing a polishing pad of the present invention, particularly a method for manufacturing a polishing layer of a polishing pad, will be described. The method for producing a polishing pad includes, for example, a preparatory step of preparing a polyisocyanate compound and/or urethane prepolymer and a curing agent; a mixed liquid for forming a molded body by mixing the polyisocyanate compound and/or urethane prepolymer and a curing agent; A mixing step for forming a cured resin molded body from a mixture solution for molding a molded body; and a polishing step for forming a polishing layer having a polishing surface for polishing an object to be polished from the cured resin molded body. A manufacturing method including a layer forming step is mentioned.

Hereinafter, the preparation process, mixing process, molded body forming process, and polishing layer forming process will be explained separately.

<Preparation process>
In order to manufacture the polishing pad of the present invention, a polyisocyanate compound and/or urethane prepolymer and a curing agent are prepared as raw materials for a cured resin molded body. In addition, hollow microspheres, abrasive grains, and additives are also prepared if necessary.

In the preparation step, if components other than those mentioned above are used in combination without impairing the effects of the present invention, those components are also prepared. Each component will be explained below.

[Polyisocyanate compound]
In this specification and claims, a polyisocyanate compound means a compound having two or more isocyanate groups in the molecule. The polyisocyanate compound can be used as a raw material for the cured resin constituting the polishing layer. The polyisocyanate compound is not particularly limited as long as it can form a cured resin. Furthermore, by reacting polyisocyanate compounds with polyol compounds, urethane prepolymers containing urethane bonds and isocyanate groups in the molecule can be prepared, and the urethane prepolymers can also be used as raw materials for cured resins. can. In addition, in this invention, the polyisocyanate compound may be comprised from several components within the range which does not impair the effect of this invention.

The polyisocyanate compound is not particularly limited as long as it has two or more isocyanate groups in the molecule. For example, diisocyanate compounds having two isocyanate groups in the molecule 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, Ethyridine diisothiocyanate and the like can be mentioned.
As the polyisocyanate compound, diisocyanate compounds are preferred, with 2,4-TDI, 2,6-TDI and MDI being more preferred, and 2,4-TDI and 2,6-TDI being particularly preferred.
When these polyisocyanate compounds are used as raw materials for urethane prepolymers, they may be used alone or in combination of a plurality of polyisocyanate compounds.

[Urethane prepolymer]
In the present invention, a urethane prepolymer can be used as a raw material. As the urethane prepolymer, a commercially available one may be used, or one synthesized by reacting a polyisocyanate compound and a polyol compound may be used. There is no particular restriction on the reaction for synthesis, and the addition polymerization reaction may be carried out using methods and conditions known in the production of polyurethane resins. For example, a polyisocyanate compound heated to 50°C is added to a polyol compound heated to 40°C while stirring in a nitrogen atmosphere, the temperature is raised to 80°C after 30 minutes, and the reaction is further carried out at 80°C for 60 minutes. It can be manufactured by such methods. Incidentally, specific examples of the polyisocyanate compound that can be used in the synthesis of the urethane prepolymer include the same polyisocyanate compounds described above as the raw materials of the present invention.

[Polyol compound (urethane prepolymer raw material)]
In this specification and claims, a polyol compound means a compound having two or more hydroxyl groups (OH) in the molecule. A polyol compound can be reacted with a polyisocyanate compound to obtain a urethane prepolymer.
Polyol compounds used in the synthesis of urethane prepolymers include diol compounds such as ethylene glycol, diethylene glycol (DEG), butylene glycol, triol compounds, etc.; poly(oxytetramethylene) glycol (or polytetramethylene ether glycol) (PTMG); Polyester polyol compounds such as reaction products of ethylene glycol and adipic acid and reaction products of butylene glycol and adipic acid; polycarbonate polyol compounds, polycaprolactone polyol compounds, and the like. Moreover, trifunctional propylene glycol to which ethylene oxide is added can also be used. Among these, PTMG or a combination of PTMG and DEG is preferred.
When the above polyol compound is used as a raw material for a urethane prepolymer, it may be used alone, or a plurality of polyol compounds may be used in combination.

[NCO equivalent of polyisocyanate compound and urethane prepolymer]
NCO equivalent can be mentioned as an index showing the characteristics of a polyisocyanate compound. The NCO equivalent is determined by "molecular weight of polyisocyanate compound/number of functional groups per molecule of polyisocyanate compound" and is a numerical value indicating the molecular weight of PP (prepolymer) per NCO group. The NCO equivalent of the urethane prepolymer synthesized by reacting a polyisocyanate compound and a polyol is "(parts by mass of polyisocyanate compound + parts by mass of polyol compound)/[(functionality per molecule of polyisocyanate compound)". It is determined as follows: number of groups x parts by mass of polyisocyanate compound/molecular weight of polyisocyanate compound) - (number of functional groups per molecule of polyol compound x parts by weight of polyol compound/molecular weight of polyol compound)]. The NCO equivalent of the polyisocyanate compound and the NCO equivalent of the urethane prepolymer are preferably from 200 to 800, more preferably from 250 to 700, even more preferably from 300 to 600.

[Curing agent]
The polishing layer 2 uses at least one of a polyisocyanate compound and/or a urethane prepolymer and a curing agent that have different reaction rates. From the viewpoint of controlling the reaction, preferably two or more of either a polyisocyanate compound and/or a urethane prepolymer and a curing agent are used, and one type of the other is used, and more preferably one type of polyisocyanate compound or urethane prepolymer is used. Two or more types of curing agents having different reaction rates are used for one type of urethane prepolymer, and more preferably, at least a polyol compound curing agent and a polyamine compound curing agent having different reaction rates are used for one type of urethane prepolymer. By doing so, it is possible to obtain a cured resin that undergoes phase separation due to the difference in reaction rate. For example, in order to obtain a gyroid structure, it is necessary to appropriately select curing agents with different compatibility and reactivity with polyisocyanate compounds and/or urethane prepolymers, and to adjust the content ratio of multiple types of curing agents. , the sea-island structure can be avoided. More specifically, if the compatibility of multiple curing agents is too low, if the reactivity is significantly different, or if the content ratio of a specific curing agent is too high (too low), a completely phase-separated sea-island structure will occur. There is a tendency to On the other hand, if the compatibility of a plurality of curing agents is too high or the reactivities are too close, a substantially uniform copolymer (or random copolymer) tends to result. Furthermore, by adding a known catalyst to control the reaction rate, it may be possible to avoid forming a sea-island structure.

By adding a curing agent, in the subsequent molding step, the main chain ends of the polyisocyanate compound and/or urethane prepolymer combine with the curing agent to form a polymer chain and are cured.

As the curing agent, it is preferable to use a curing agent capable of curing the polyisocyanate compound and/or urethane prepolymer, for example, a curing agent that polymerizes NCO groups is preferable.
As the curing agent, for example, a polyamine compound and/or a polyol compound can be used.

(Polyamine compound (curing agent))
In this specification and claims, a polyamine compound is a compound that can be used as a curing agent, and means a compound having two or more amino groups in the molecule.
As the polyamine compound, aliphatic or aromatic polyamine compounds, especially diamine compounds can be used, such as ethylenediamine, propylene diamine, hexamethylene diamine, isophorone diamine, dicyclohexylmethane-4,4'-diamine, 3 , 3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (hereinafter abbreviated as MOCA), and polyamine compounds having a structure similar to MOCA. Further, the polyamine compound may have a hydroxyl group, and examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, and di-2-hydroxyethylethylenediamine. Examples include ethylpropylene diamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine.
As the polyamine compound, diamine compounds are preferred, MOCA, diaminodiphenylmethane, and diaminodiphenylsulfone are more preferred, and MOCA is particularly preferred.

Here, examples of MOCA include PANDEX E (manufactured by DIC Corporation), Iharakyuamine MT (manufactured by Kumiai Chemical Co., Ltd.), and the like.
A polyamine compound may be used alone, or a plurality of polyamine compounds may be used in combination.

The polyamine compound is preferably defoamed under reduced pressure while being heated if necessary, in order to facilitate mixing with other components and/or to prevent the formation of unintended bubbles in the subsequent molded body forming step. As a defoaming method under reduced pressure, a method known in the production of polyurethane resins may be used. For example, defoaming can be performed using a vacuum pump at a vacuum degree of 0.1 MPa or less.
When a solid compound is used as a curing agent (chain extender), it can be defoamed under reduced pressure while being melted by heating.

The NH2 equivalent of the polyamine compound is preferably 50 or more and 300 or less, more preferably 70 or more and 250 or less, and even more preferably 80 or more and 200 or less.

(Polyol compound (curing agent))
Moreover, polyols can be used as a curing agent. Examples of polyols as curing agents include diol compounds, triol compounds such as ethylene glycol, diethylene glycol (DEG), polypropylene glycol (PPG), butylene glycol; poly(oxytetramethylene) glycol (or polytetramethylene ether glycol) ( Polyether polyol compounds such as PTMG); polyester polyol compounds such as reaction products of ethylene glycol and adipic acid and reaction products of butylene glycol and adipic acid; polycarbonate polyol compounds, polycaprolactone polyol compounds, etc. Moreover, trifunctional propylene glycol to which ethylene oxide is added can also be used. Among these, PPG, PTMG, and a combination of PPG and PTMG are preferred.
The above polyol compounds may be used alone, or a plurality of polyol compounds may be used in combination. Further, when a polyol is used as a raw material for urethane prepolymer synthesis, it can be used in combination with a polyol as a curing agent, and they may be the same or different.

The OH equivalent of the polyol is preferably 100 or more and 3000 or less, more preferably 200 or more and 2500 or less, and even more preferably 250 or more and 2000 or less.

When using multiple types of polyols, the difference in OH equivalent between the polyol with the highest OH equivalent and the polyol with the lowest OH equivalent among the polyols used is preferably 300 or more, and preferably 500 or more. More preferably, it is 700 or more, particularly preferably 800 or more.

When creating a gyroid structure by using two types of curing agents with different reaction rates, for example, active hydrogen groups (amino It is preferable to use a curing agent with an active hydrogen equivalent of 2.5 times or more and a curing agent with an active hydrogen equivalent of 0.5 times or less. It is more preferable to use the following curing agents. In addition, when three or more types of curing agents are used, the "active hydrogen equivalent to the NCO equivalent of the polyisocyanate compound and/or urethane prepolymer" of at least one type of curing agent is 0.5 times or less, and It is sufficient that the "active hydrogen equivalent to the NCO equivalent of the polyisocyanate compound and/or urethane prepolymer" of the curing agent is 2.5 times or more.
The curing agent whose "active hydrogen equivalent to the NCO equivalent of the polyisocyanate compound and/or urethane prepolymer" is 0.5 times or less is preferably 10% by weight or more of the entire curing agent, and the "polyisocyanate compound and/or urethane prepolymer The curing agent whose active hydrogen equivalent is 2.5 times or more relative to the NCO equivalent of the urethane prepolymer is preferably 10% by weight or more of the entire curing agent.

When two types of curing agents are used, the content of one curing agent is preferably 10% by weight or more, more preferably 20% by weight or more, and 30% by weight when the total amount of the curing agent is 100% by weight. It is more preferable to do the above. If the amount of one of the curing agents is too small, the gyroid structure cannot be achieved and the structure tends to become a sea-island structure.

<Mixing process>
In the mixing step, the polyisocyanate compound and/or urethane prepolymer and curing agent obtained in the preparation step, and, if necessary, hollow microspheres, abrasive grains, a foaming agent, a foam stabilizer, an antifoaming agent, a catalyst, a pigment, Additives such as dyes, hydrophilic agents, hydrophobic agents, antistatic agents, flame retardants, light stabilizers, antioxidants, and dispersants are fed into a mixer and stirred and mixed. The mixing step is carried out at a temperature that ensures the fluidity of each of the above components.
In the mixing step, at least the polyisocyanate compound and/or urethane prepolymer and curing agent are fed into a mixer and stirred and mixed. There is no particular restriction on the mixing order, but a liquid containing a polyisocyanate compound and/or urethane prepolymer and a liquid containing a curing agent and other components as necessary are prepared and both liquids are fed into a mixer. It is preferable to mix and stir the mixture. In this way, a liquid mixture for molding a molded body is prepared. The mixing step is carried out at a temperature that ensures the fluidity of each of the above components.

<Molded object forming process>
In the molding process, the liquid mixture for molding the molded body prepared in the mixing process is poured into a mold that has been preheated to 30 to 150°C, and heated at about 30 to 150°C for about 10 minutes to 5 hours to harden. to form a cured resin (resin molded body). At this time, the mixed liquid is cured by reacting the polyisocyanate compound, the urethane prepolymer, and the curing agent to form a cured resin.

<Polishing layer formation process>
The cured resin molded body obtained by the molded body molding process is sliced into sheet shapes to form cured resin sheets.

The abrasive layer having the cured resin sheet thus obtained is then placed in a double-sided tape on the opposite side of the abrasive layer from the abrasive surface and pasted on the cushion layer to form a predetermined shape, preferably a disk shape. Then, the polishing pad of the present invention is completed. There are no particular restrictions on the double-sided tape, and any double-sided tape known in the art can be selected and used.

Further, the polishing pad of the present invention may have a single-layer structure consisting of only the polishing layer, and another layer (lower layer, support layer, cushion layer in FIG. 1) is provided on the surface opposite to the polishing surface of the polishing layer. It may also consist of a multi-layer structure made by laminating two layers together. Although the characteristics of the other layers are not particularly limited, it is preferable that a layer softer than the polishing layer (having a smaller A hardness or D hardness) is bonded to the opposite surface of the polishing layer. If a layer softer than the polishing layer is attached, the polishing performance for curved surfaces is further improved. On the other hand, if a layer harder than the polishing layer (having a larger A hardness or D hardness) is bonded to the opposite surface of the polishing layer, it is possible to suppress the end sag of the object to be polished.

In the case of having a multilayer structure, the plurality of layers may be bonded and fixed together using double-sided tape, adhesive, or the like, applying pressure if necessary. There are no particular restrictions on the double-sided tape or adhesive used in this case, and any double-sided tape or adhesive known in the art can be selected and used.

Furthermore, in the polishing pad of the present invention, the surface and/or back surface of the polishing layer may be subjected to grinding treatment, groove processing, etc., and the base material and/or the adhesive layer are bonded to the polishing layer. Alternatively, a light transmitting portion may be provided.
There is no particular restriction on the method of the grinding treatment, and the grinding can be performed by any known method. Specifically, grinding with sandpaper can be mentioned.
There is no particular restriction on the shape of the groove, and examples thereof include a lattice shape, a concentric circle shape, a radial shape, a spiral shape, and the like.

When using the polishing pad of the present invention, the polishing pad is attached to a polishing surface plate of a polishing machine with the polishing surface of the polishing layer facing the object to be polished. Then, while supplying the polishing slurry, the polishing surface plate is rotated to polish the processed surface of the object to be polished.

<Dress processing>
In this specification, dressing processing refers to processing in which a dresser is used to polish only a small amount of the surface of a polishing pad. Examples of this dresser include a pad dresser obtained by electrodepositing diamond abrasive grains on the surface of a disc-shaped base material, or a pellet dresser obtained by embedding diamond pellets in the surface of the base material. .

When using the polishing pad of the present invention, the polishing pad is attached to a polishing surface plate of a polishing machine with the polishing surface of the polishing layer facing the object to be polished. Then, while supplying the abrasive slurry, the polishing surface plate is rotated to polish the processed surface of the object to be polished.
Objects to be polished by the polishing pad of the present invention include precision parts such as optical glass, semiconductor wafers, semiconductor devices, hard disk substrates, and plastic lenses. Among these, the polishing pad of the present invention is suitably used for chemical mechanical polishing (CMP) of optical members such as optical glass and plastic lenses for eyeglasses.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

The R value is a numerical value indicating the equivalent ratio of active hydrogen groups (amino groups and hydroxyl groups) present in the curing agent to the terminal isocyanate groups in the polyisocyanate compound and/or urethane prepolymer. From the viewpoint of controlling the reaction, the R value is preferably from 0.6 to 1.4, preferably from 0.7 to 1.3, and particularly preferably from 0.8 to 1.2.

The SEM photograph was taken using a product name "JSM-5500LV" manufactured by JEOL Ltd.

<Examples 1 to 3, Comparative Example 1 (Resins 1 to 4)>
A mixture of a prepolymer, a curing agent, and an additive was supplied to a mixer at a predetermined ratio (% by mass) shown in Table 1. The resulting mixed solution was supplied to a mold while being stirred and cured at 80° C. for 30 minutes to obtain Resins 1 to 4 having the structures shown in the photographs shown in FIGS. 2 to 5.

Resins 1 to 4 were sliced to a predetermined thickness, and a polishing pad having the slices as a polishing layer was manufactured. When the surface of the obtained polishing pad was observed by SEM, it was confirmed that each of Resins 1 to 3 had microphase separation in a gyroid structure, as shown in FIGS. 2 to 4. Having such a structure makes it difficult for the surface of the polishing pad to wear uniformly, so that smoothing of the polishing surface can be suppressed and dressing properties can be improved. Moreover, since the structure is not such that the specific resin is scattered in the form of islands, it is possible to suppress the island parts from falling off in chunks. On the other hand, the resin 4 of Comparative Example 1, which did not use a curing agent with an active hydrogen equivalent of 2.5 times or more with respect to the NCO equivalent of the urethane prepolymer (polyisocyanate compound), was almost homogeneous as shown in FIG. The structure was confirmed.

The curing agent used is as follows.
Prepolymer A: Urethane prepolymer containing tolylene diisocyanate as the main component (NCO equivalent: 405)
Curing agent B1: MOCA (NH2 equivalent 133.5)
Curing agent B2: polytetramethylene glycol (OH equivalent: 500)
Curing agent B3: Polypropylene glycol (OH equivalent: 1775)
Curing agent B4: polytetramethylene glycol (OH equivalent: 325)
Curing agent B5: polytetramethylene glycol (OH equivalent 1000)
Additive C1: Catalyst (dimethylaminopyridine, manufactured by Koei Chemical Industry Co., Ltd.)
Additive C2: Antifoaming agent (71, manufactured by Dow Corning Toray)
Additive C3: Catalyst (Toyocat ET, manufactured by Tosoh Corporation)

Claims (5)

A polishing pad in which a cured resin constituting a polishing layer is phase-separated in a gyroid structure,
At least one of the phase-separated cured resins is selected from the group consisting of polyurethane resins, polyurea resins, and polyurethane polyurea resins,
The cured resin contains at least two types of curing agents for curing the prepolymer of the cured resin, and the two or more types of curing agents have different reaction rates to the prepolymer. (excluding polishing pads having a polishing layer made of a photocured resin composition). The polishing pad according to claim 1, wherein all of the cured resins constituting the polishing layer are selected from the group consisting of polyurethane resins, polyurea resins, and polyurethane polyurea resins. The polishing pad according to claim 1 or 2, wherein the polishing layer has a density of 0.9 to 1.2 g/cm ³ . A method for manufacturing a polishing layer of a polishing pad in which a cured resin constituting the polishing layer is phase-separated in a gyroid structure, the method comprising:
At least one of the phase-separated cured resins is selected from the group consisting of polyurethane resins, polyurea resins, and polyurethane polyurea resins,
The manufacturing method includes:
A step of preparing one or more types of polyisocyanate compounds and/or urethane prepolymers;
A step of preparing one or more types of curing agent (however, if the polyisocyanate compound and/or urethane prepolymer is one type, the number of curing agents is two or more types);
A method comprising the step of curing the polyisocyanate compound and/or urethane prepolymer by mixing the polyisocyanate compound and/or urethane prepolymer and the curing agent. The resin obtained by curing the polyisocyanate compound and/or urethane prepolymer is a polyurethane polyurea resin,
The curing agent is two or more types of curing agents selected from polyol compounds and polyamine compounds,
The active hydrogen equivalent of one of the curing agents is 2.5 times or more of the NCO equivalent of at least one of the polyisocyanate compound and/or urethane prepolymer, and the equivalent of the other curing agent is 2.5 times or more The method according to claim 4, wherein the active hydrogen equivalent is 0.5 times or less with respect to the NCO equivalent of at least one type of the polyisocyanate compound and/or urethane prepolymer.