JP7118841B2 - polishing pad - Google Patents

Description

The present invention relates to polishing pads. Specifically, the present invention can be used for polishing optical materials, semiconductor wafers, semiconductor devices, substrates for hard disks, etc., and in particular for polishing devices having oxide layers, metal layers, etc. formed on semiconductor wafers. It relates to a polishing pad that can be suitably used for

As the degree of integration of semiconductor devices increases, miniaturization and multi-layering are progressing. Therefore, polishing of glass substrates and the like used for semiconductor devices is required to remove polishing scratches (suppression of defects and scratches) in addition to productivity.

As a polishing method that satisfies such a demand, among various polishing methods, it is common to employ a free abrasive polishing method. The free abrasive grain method is a method of polishing the surface of the object to be polished while supplying slurry (polishing liquid) containing abrasive grains between the polishing pad and the object to be polished.

In free-abrasive polishing, after the polishing pad is attached to the polishing device and before the actual polishing, the surface of the polishing pad (polishing surface) is roughened by a dressing process using a diamond abrasive disc, etc. It is common practice to do By performing the dressing process, it is possible to perform so-called break-in (start-up) to improve the polishing performance of the polishing pad. In order to increase the productivity of semiconductor wafers, it is desired to shorten the time required for such break-in.

Patent Document 1 discloses a polishing pad capable of shortening the time required for break-in by setting the average surface roughness (Ra) of the polishing pad surface to 1 μm or more and 5 μm or less.

International Publication No. 2008/029725

However, by simply adjusting the average surface roughness (Ra), even if the time required for break-in can be shortened, there are cases where the desired polishing performance is not exhibited due to large defects in the initial stage of subsequent polishing. I understood it.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a polishing pad that reduces defects in the initial stage of polishing while shortening the time required for break-in.

As a result of extensive research, the inventors of the present invention have found that the arithmetic mean height (Sa) and the arithmetic mean curvature of the peak points (Spc), which is the average of the principal curvatures of the peak points of the polishing layer surface, are within a predetermined range. The inventors have found that the break-in time can be shortened and the number of defects can be reduced by using a polishing pad, and the present invention has been achieved. That is, the present invention includes the following.
[1] A polishing pad having a polishing layer for polishing an object to be polished, wherein the arithmetic mean height ( Sa) is 3 to 10 (μm), and the arithmetic mean curvature (Spc) of the peak points, which is the average of principal curvatures of the peak points of the polished surface, is 200 to 600 (1/mm). , polishing pad,
[2] The polishing pad according to [1], wherein the peak density (Spd) representing the number of peak points per unit area of the polishing surface is 2000 to 6000 (1/mm ² ). ,
[3] The polishing according to [1] or [2], which includes a step of performing buffing under conditions where the ratio of the peripheral speed of the paper to the speed of the platen (paper peripheral speed/platen speed) is 50 to 750. How the pad is made.

The polishing pad of the present invention can shorten the break-in time and reduce defects in the early stage of polishing.

FIG. 1 is a perspective view of the polishing pad of the present invention. FIG. 2 is a cross-sectional view of the polishing pad of the present invention. FIG. 3 is a cross-sectional view of hollow microspheres included in the polishing pad of the present invention. FIG. 4 is an SEM photograph of the polishing surface of the reference polishing pad. 5 is an SEM photograph of the polishing surface of the polishing pad of Example 1. FIG. 6 is an SEM photograph of the polishing surface of the polishing pad of Example 2. FIG. 7 is an SEM photograph of the polishing surface of the polishing pad of Comparative Example 1. FIG.

DETAILED DESCRIPTION OF THE INVENTION Embodiments for carrying out the invention will be described below, but the present invention is not limited only to the embodiments for carrying out the invention.

In this specification, Ra refers to the average of the absolute values of the difference in height of each point with respect to the average line of the sampled portion of the reference length l extracted in the direction of the average line of the target surface. It is specified in JIS B 671-1/ISO 13565-1 (line roughness measurement).

In this specification, Sa represents the average of the absolute values of the difference in height at each point of the sampled reference area A with respect to the reference plane of the surface. In this specification, the unit of Sa is (μm).

As used herein, Spc represents the mean of the principal curvatures of the crest points of the surface. That is, it is the arithmetic mean curve of the peak points, which is the average of the principal curvatures of the peak points of the polishing layer surface. A small Spc value indicates that the point of contact with another object is rounded, and a large Spc value indicates that the point of contact with another object is sharp. In this specification, the unit of Spc is (1/mm).

In this specification, Spd represents the number of summit points per unit area. A large value indicates that there are many contact points with other objects. In this specification, the unit is (1/mm ² ).

Note that Sa, Spc, and Spd are all defined by ISO 25178 (three-dimensional surface properties (surface roughness)).

<<Polishing pad>>
The polishing pad of the present invention will be explained.
Generally, even if a polishing pad that is first polished after production is used for polishing without surface treatment on the polishing surface, the polishing rate is not sufficient, and it is difficult to say that the polishing can be properly performed. Therefore, in the initial stage of polishing, dressing processing and preliminary polishing are repeated, and after a sufficient polishing rate is achieved, the actual product is polished.
However, with the polishing pad of the present invention, it is possible to perform polishing at a sufficient polishing rate even if no dressing treatment is performed, or even if the dressing treatment is performed for a shorter period of time than normal dressing treatment.

The structure of the polishing pad of the present invention will be described with reference to FIGS. 1 to 3. FIG. As shown in FIG. 1, the polishing pad 1 includes a polishing layer 2, which is a layer that contacts and polishes an object to be polished. The polishing layer 2 has a polishing surface 2a that contacts 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. The shape may be disk-shaped, band-shaped, or the like, and disk-shaped is preferable.
The size (diameter) of the polishing pad 1 can be determined according to the size of the polishing apparatus including the polishing pad 1, and can be, for example, about 10 cm to 1 m in diameter.
The polishing layer 2 preferably has a thickness of 0.1 mm to 10 mm, more preferably 0.3 mm to 5 mm.
The polishing pad of the present invention may be composed only of the polishing layer.

In the polishing pad 1 , it is preferable that the polishing layer 2 is adhered to the cushion layer 4 via the 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 an adhesive tape or an adhesive material.

The cushion layer 4 is a layer that makes the contact of the polishing layer 2 with the object to be polished more uniform. 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 the polishing device by means of an adhesive tape or the like provided on the cushion layer 4 . The polishing pad 1 is driven to rotate while being pressed against the object to be polished by the 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 fed to and discharged from the polishing surface through the grooves or holes.

<Polishing layer>
The material constituting the polishing layer 2 is the resin 6 which is the main component of the polishing layer 2 . In addition, hollow microspheres 5 may be further included, if necessary.

When the polishing layer 2 contains hollow microspheres 5, it is preferable that the hollow microspheres 5 are dispersed in the resin 6 as shown in FIG.

Hollow microspheres 5 that can be included in the polishing layer 2, for example, as shown in FIG. have. The hollow microspheres 5 have a shape in which a liquid low-boiling-point hydrocarbon is wrapped with an outer shell 5a of a thermoplastic resin.

The details of the resin 6 and the hollow microspheres 5 will be described in the section <<Manufacturing Method of Polishing Pad>>.

<Polished surface>
The polishing surface 2a of the polishing layer 2 provided in the polishing pad 1 of the present invention can be provided with grooves, if necessary, by surface processing. The grooves may be orthogonal grooves (X-axis and Y-axis), perforated grooves (drilled grooves), concentric circular grooves, or the like. Sa, Spa, and Spd of the polished surface will be described later.

<<Manufacturing Method of Polishing Pad>>
A method for manufacturing the polishing pad of the present invention will be described. The material of the polishing pad is not particularly limited as long as it can be used for polishing. For example, a polyurethane resin material obtained by reacting a urethane bond-containing polyisocyanate compound with a curing agent can be mentioned. be able to. The method for producing a polishing pad will be described below using a polyurethane resin polishing pad obtained by using a urethane bond-containing polyisocyanate compound and a curing agent as an example.

A method for producing a polishing pad using a urethane bond-containing polyisocyanate compound and a curing agent includes, for example, a preparation step of preparing at least a urethane bond-containing polyisocyanate compound, a curing agent, and optionally hollow microspheres; , a mixing step of mixing the urethane bond-containing polyisocyanate compound, the curing agent, and the hollow microspheres to obtain a mixed liquid for molding a molded body; a molded body molding process of molding a polyurethane resin molded body from the mixed liquid for molded body molding. and a polishing layer forming step of forming a polishing layer having a polishing surface for polishing the object to be polished from the polyurethane resin molded article.

The preparation process, the mixing process, the molding process, and the polishing layer forming process will be described separately below.

<Preparation process>
In order to manufacture the polishing pad of the present invention, a urethane bond-containing polyisocyanate compound and a curing agent are prepared as raw materials for the polyurethane resin molding (curing resin). In addition, hollow microspheres or water are prepared for the purpose of including the foam in the resin molding. Here, the urethane bond-containing polyisocyanate is a prepolymer for forming a polyurethane resin molding.

In the preparation step, when a polyol compound is used together with the above components, or when components other than those described above are used together within the range that does not impair the effects of the present invention, those components are also prepared. Each component will be described below.

[Urethane bond-containing polyisocyanate compound]
A urethane bond-containing polyisocyanate compound (prepolymer) is a compound obtained by reacting the following polyisocyanate compound and a polyol compound under commonly used conditions, and contains a urethane bond and an isocyanate group in the molecule. Further, other components may be contained in the urethane bond-containing polyisocyanate compound within a range that does not impair the effects of the present invention.

As the urethane bond-containing polyisocyanate compound, a commercially available one may be used, or a compound synthesized by reacting a polyisocyanate compound and a polyol compound may be used. The reaction is not particularly limited, and an addition polymerization reaction may be carried out using a method and conditions known in the production of polyurethane resins. For example, to a polyol compound heated to 40° C., a polyisocyanate compound heated to 50° C. is added while stirring in a nitrogen atmosphere, and after 30 minutes the temperature is raised to 80° C. and further reacted at 80° C. for 60 minutes. It can be manufactured by such a method.

[Polyisocyanate compound]
In the present specification and claims, a polyisocyanate compound means a compound having two or more isocyanate groups in its molecule.
The polyisocyanate compound is not particularly limited as long as it has two or more isocyanate groups in its 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 preferable, 2,4-TDI, 2,6-TDI and MDI are more preferable, and 2,4-TDI and 2,6-TDI are particularly preferable.
These polyisocyanate compounds may be used alone or in combination of multiple polyisocyanate compounds.

[Polyol compound as raw material for prepolymer]
In the present specification and claims, a polyol compound means a compound having two or more hydroxyl groups (OH) in its molecule.
Examples of the polyol compound used for synthesizing the urethane bond-containing polyisocyanate compound as the prepolymer include diol compounds such as ethylene glycol, diethylene glycol (DEG) and butylene glycol; triol compounds; polyether polyol compounds such as methylene ether glycol (PTMG); polyester polyol compounds such as reaction products of ethylene glycol and adipic acid and butylene glycol and adipic acid; polycarbonate polyol compounds, polycaprolactone polyol compounds, and the like. be able to. Also, trifunctional propylene glycol to which ethylene oxide is added can be used. Among these, PTMG or a combination of PTMG and DEG is preferred.
The above polyol compound may be used alone, or a plurality of polyol compounds may be used in combination.

(NCO equivalent of prepolymer)
As an index showing the characteristics of the urethane bond-containing polyisocyanate compound, which is a prepolymer, there is an NCO equivalent. 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) - (polyol compound 1 The number of functional groups per molecule×parts by mass of polyol compound/molecular weight of polyol compound)]”, and is a numerical value indicating the molecular weight of PP (prepolymer) per NCO group. The NCO equivalent is preferably 200-800, more preferably 300-700, even more preferably 400-600.

[Curing agent]
In the method for producing a polishing pad of the present invention, a curing agent (also referred to as a chain extender) is mixed with a urethane bond-containing polyisocyanate compound or the like in the mixing step. By adding a curing agent, the main chain end of the urethane bond-containing polyisocyanate compound bonds with the curing agent to form a polymer chain and cures in the subsequent molding step.
As a curing agent, for example, a polyamine compound and/or a polyol compound can be used.

[Polyamine compound]
In the present specification and claims, a polyamine compound means a compound having two or more amino groups in its molecule.
As polyamine compounds, aliphatic or aromatic polyamine compounds, particularly diamine compounds, can be used. ,3'-dichloro-4,4'-diaminodiphenylmethane (methylenebis-o-chloroaniline) (hereinafter abbreviated as MOCA), polyamine compounds having the same structure as MOCA, and the like. In addition, the polyamine compound may have a hydroxyl group. Examples of such amine compounds include 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxy Ethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine and the like can be mentioned.
As the polyamine compound, a diamine compound is preferable, MOCA, diaminodiphenylmethane, and diaminodiphenylsulfone are more preferable, and MOCA is particularly preferable.

Examples of MOCA include PANDEX E (manufactured by DIC) and Iharakyuamine MT (manufactured by Kumiai Chemical Co., Ltd.).
The polyamine compound may be used alone or in combination of multiple polyamine compounds.

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

[Polyol compound that may be used after prepolymer synthesis]
Moreover, in the present invention, a polyol compound may be used as a curing agent in addition to the polyol compound used for forming the urethane bond-containing polyisocyanate compound as the prepolymer.
As the polyol compound, any compounds such as diol compounds and triol compounds can be used without particular limitation. It may also be the same as or different from the polyol compound used to form the prepolymer.
Specific examples include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3 low molecular weight diols such as -methyl-1,5-pentanediol and 1,6-hexanediol; and high molecular weight polyol compounds such as poly(oxytetramethylene)glycol, polyethylene glycol and polypropylene glycol.
The above polyol compound may be used alone, or a plurality of polyol compounds may be used in combination.

As the curing agent, a polyamine compound may be used, a polyol compound may be used, or a mixture thereof may be used.

(R value)
In the method for producing a polishing pad of the present invention, the R value 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 urethane bond-containing polyisocyanate compound as the prepolymer. However, it is preferable to mix each component so that the value is 0.60 to 1.40. The R value is more preferably 0.70 to 1.20, even more preferably 0.80 to 1.10.

[Hollow microspheres]
In the method of manufacturing the polishing pad of the present invention, hollow microspheres or water can be used as necessary to enclose air bubbles inside the polyurethane resin molding.
Hollow microspheres refer to microspheres having voids. Hollow microspheres include spherical, ellipsoidal, and approximating shapes. As an example, unfoamed heat-expandable microspheres may be heat-expanded.
Examples of the polymer shell include acrylonitrile-vinylidene chloride copolymer, acrylonitrile-methyl methacrylate copolymer, vinyl chloride-ethylene copolymer, etc., as disclosed in JP-A-57-137323. A thermoplastic resin can be used. 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.

Commercially available hollow microspheres can also be used. For example, the Matsumoto Microsphere series (manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) and the Expancel series (manufactured by AkzoNobel) can be used as hollow microspheres. 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 hollow microspheres It is necessary to adjust the reaction conditions such that the expansion is forcibly suppressed by

It is preferable to use hollow microspheres having an average particle diameter of 10 to 150 μm. The average particle diameter of the expanded type hollow microspheres is more preferably 15 to 130 μm, even more preferably 20 to 100 μm, even more preferably 20 to 60 μm, even more preferably 30 to 50 μm. is particularly preferred. Since the expanded type is already expanded, the average particle diameter of the hollow microspheres before inclusion in the resin and the average bubble diameter of the hollow microspheres after forming the polishing layer do not differ greatly.
In addition, since only expanded types with an average particle size of 20 μm or more are commercially available, unexpanded hollow microspheres with an average particle size of 10 to 20 μm are used when it is desired to make the bubble diameter in the resin less than 20 μm. , the reaction conditions must be adjusted to control the hollow microspheres from expanding 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 particle size of the hollow microspheres before use can be measured with a laser diffraction particle size distribution analyzer (eg Mastersizer 2000 manufactured by Spectris Co., Ltd.).
Also, the average bubble diameter of the hollow microspheres in the polishing pad can be measured by performing image processing on the measurement image of the laser microscope.

Hollow microspheres are preferably 10 to 60% by volume, more preferably 15 to 45% by volume, relative to the material of the polishing layer. The hollow microspheres are exposed on the polishing surface when the polishing layer is worn by polishing, and affect the polishing characteristics of the polishing surface.

Hollow microspheres are added in an amount of preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, and even more preferably 2 to 4 parts by weight, per 100 parts by weight of the prepolymer.

<Mixing process>
In the mixing step, the urethane bond-containing polyisocyanate compound (prepolymer) and the curing agent obtained in the preparation step are fed into the mixer and stirred and mixed. The mixing step is carried out in a state where the components are heated to a temperature that ensures the fluidity of the components.
In the mixing step, at least the urethane bond-containing polyisocyanate compound (prepolymer), the curing agent and the hollow microspheres are fed into the mixer and stirred and mixed. There are no particular restrictions on the mixing order, but a mixed solution in which a urethane bond-containing polyisocyanate compound and hollow microspheres are mixed and a mixed solution in which a curing agent and, if necessary, other components are mixed are prepared, and both mixed solutions are prepared. is preferably fed into a mixer and mixed and stirred. In this manner, a mixed solution for forming a molded body is prepared. The mixing step is carried out in a state where the components are heated to a temperature that ensures the fluidity of the components.

<Molding body molding process>
In the molded body molding step, the molded body molding mixed liquid prepared in the mixing step is poured into a mold preheated to 30 to 100° C. for primary curing, and then heated to about 100 to 150° C. for about 10 minutes to 5 hours. A cured polyurethane resin (polyurethane resin molded article) is formed by heating and secondary curing. At this time, the mixture is cured by reacting the prepolymer and the curing agent to form a polyurethane resin.

<Polishing layer forming process>
The polyurethane resin molded article obtained in the molded article forming step is sliced into sheets to form polyurethane resin sheets. By slicing, the sheet surface is provided with openings. At this time, aging may be performed at 30 to 150° C. for about 1 to 24 hours in order to form pores on the surface of the polishing layer which are excellent in abrasion resistance and are not easily clogged.

The polishing layer having the polyurethane resin sheet thus obtained is then pasted with a double-sided tape on the surface opposite to the polishing surface of the polishing layer, and cut into a predetermined shape, preferably a disc shape. The polishing pad of the present invention is completed. The double-sided tape is not particularly limited, and can be used by arbitrarily selecting from double-sided tapes known in the art.

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) may be provided on the surface opposite to the polishing surface of the polishing layer. It may be composed of multiple layers laminated together. Although the properties of the other layers are not particularly limited, it is preferable that a layer that is softer than the polishing layer (lower in A hardness or D hardness) than the polishing layer is laminated on the opposite side of the polishing layer. When a layer softer than the polishing layer is attached, polishing flatness is further improved. On the other hand, if a layer harder than the polishing layer (larger in A hardness or D hardness) than the polishing layer is adhered to the opposite side of the polishing layer, the polishing rate is further improved.

In the case of having a multi-layer structure, a plurality of layers may be adhered and fixed by using a double-sided tape, an adhesive, or the like while applying pressure as necessary. There are no particular restrictions on the double-sided tapes and adhesives used in this case, and any double-sided tapes and adhesives known in the art can be used.

Further, in the polishing pad of the present invention, the surface and/or back surface of the polishing layer may be ground, grooved or embossed, and the substrate and/or adhesive layer may be polished. It may be attached to a layer, or may have a light-transmitting portion.
There are no particular restrictions on the shape of the grooving and embossing, and examples thereof include grid-type, concentric circle-type, and radial-type shapes.

[surface treatment]
The polishing surface of the polishing pad of the present invention can be subjected to physical or chemical treatment. Even if the surface is not treated, the break-in time can be shortened and defects can be reduced if the polished surface can have Sa and Spc (Spd if necessary) within a predetermined range. However, it is preferable to carry out the surface treatment because it becomes easier to achieve the predetermined Sa and Spc when the surface treatment is carried out.
Conventionally, surface roughness was measured using a contact-type method using Ra, which is measured only in a specific line direction. was difficult to measure. According to the present invention, by measuring the surface roughness by an optical method, it is possible to measure an accurate surface state in consideration of directionality.

In the polishing pad of the present invention, buffing is one method of surface treatment for achieving Sa and Spc (Spd, if necessary) within predetermined ranges. Therefore, the polishing pad of the present invention is preferably buffed. Here, buffing is a method in which, after roughening the surface to be polished using sandpaper to some extent, a buff such as cloth, leather, rubber, or the like is pressed against the polishing surface while rotating to treat the surface. .

The number of sandpaper used for buffing in the present invention is not particularly limited, but #120 to #600 is preferable. This is because the use of such sandpaper facilitates adjustment to appropriate Sa and Spc.

In the present invention, the peripheral speed of the sandpaper in the buffing process is not particularly limited, but is preferably 300 m/min to 1500 m/min. If the peripheral speed of the paper is less than 300 m/min, the cutting force becomes low and the surface may not be sufficiently roughened. Further, when the peripheral speed of the paper exceeds 1500 m/min, the cutting force becomes too large, making it difficult to keep Sa and Spc (Spd if necessary) within the predetermined ranges.

In the present invention, the surface plate speed when pressing the buff in the buffing process is not particularly limited, but is preferably 0.1 m/min to 20 m/min.
In the present invention, the ratio of the peripheral speed of the paper to the speed of the platen (paper peripheral speed/platen speed) is preferably 50-750. By making the surface plate speed sufficiently slow with respect to the paper speed, it is possible to suppress the shearing force while keeping the cutting force in a preferable range, and to set Sa and Spc (Spd if necessary) within a predetermined range. becomes possible. When the paper peripheral speed/platen speed is less than 50, shear force is generated and unintended tearing occurs, resulting in a sharp peak shape or an increase in the number of peak points, resulting in Sa, Spc, Spd becomes difficult. On the other hand, if the paper peripheral speed/platen speed is higher than 750, the cutting force becomes too large, making it difficult to keep Sa, Spc, and Spd within the predetermined ranges.

The polishing pad of the present invention is provided with a polishing layer having Sa, Spc, and Spd within predetermined ranges without surface treatment, or with surface treatment such as buffing if necessary.

In the present invention, Sa of the polishing surface of the polishing layer is 3 to 10 μm. Within this range, there is an effect that the break-in time can be shortened. The lower limit of Sa is preferably 3 μm or more, more preferably 4 μm or more. On the other hand, the upper limit of Sa is preferably 10 μm or less, more preferably 8 μm or less.

In the present invention, the Spc of the polishing surface of the polishing layer is 200 to 600 (1/mm). Within this range, there is an effect of reducing scratches. The lower limit of Spc is preferably 200 (1/mm) or more, more preferably 300 (1/mm) or more. On the other hand, the upper limit of Spc is preferably 600 (1/mm) or less, more preferably 500 (1/mm) or less.

In the present invention, the Spd of the polishing surface of the polishing layer is preferably 2000 to 6000 (1/mm ² ). This range is preferable because it has the effect of reducing scratches. The lower limit of Spd is preferably 2000 (1/mm ² ) or more, more preferably 3000 (1/mm ² ) or more. On the other hand, the upper limit of Spd is preferably 6000 (1/mm ² ) or less, more preferably 5000 (1/mm ² ) or less.

When using the polishing pad of the present invention, the polishing pad is attached to the polishing surface plate of the polishing machine so that the polishing surface of the polishing layer faces the object to be polished. Then, while supplying the polishing slurry, the polishing surface plate is rotated to polish the processing surface of the object to be polished.

EXAMPLES The present invention will be described in detail below using examples, but the present invention is not limited to the examples.

(Measurement of surface condition)
Sa, Spc and Spd were measured using a laser microscope.

(Defect evaluation)
A polishing pad was set at a predetermined position of a polishing apparatus via a double-sided tape having an acrylic adhesive, and the Cu film substrate was subjected to polishing under the following conditions.
(polishing conditions)
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: Cu film substrate Polishing time: 60 seconds Pad break: 35N 10 minutes Conditioning: Ex-situ, 35N, 4 scans Linear polishing scratches (scratches) larger than 155 nm and dot-like polishing scratches (microscratches) were visually confirmed by review SEM of eDR5210 (manufactured by KLA-Tencor) to confirm the number of scratches.

(Production of reference polishing pad)
100 parts of an isocyanate group-terminated urethane prepolymer having an NCO equivalent of 460 obtained by reacting 2,4-tolylene diisocyanate (TDI), poly(oxytetramethylene) glycol (PTMG) and diethylene glycol (DEG), and the shell portion is acrylonitrile- 3 parts of unexpanded hollow bodies 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 warm. Next, separately from the first liquid, 25.5 parts of MOCA and 8.5 parts of polypropylene glycol (PPG) were added and mixed as a curing agent and kept warm 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 pouring the injected two liquids into a preheated mold of a molding machine while mixing and stirring, the mold was clamped and heated for 30 minutes for primary curing. After the primary cured molding was removed from the mold, it was secondary cured in an oven at 130° C. for 2 hours to obtain a urethane molding. The resulting urethane 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 slices to obtain polishing pads. The resulting polishing pad had an average cell diameter of 15 μm.

(Reference polishing pad dressing process)
The obtained polishing pad was subjected to dressing treatment without being subjected to buffing treatment. The dressing treatment uses a dresser to polish only a small amount of the surface of the polishing pad. The speed was set at 80 rpm, the dressing pressure was set at 20 N, and the slurry discharge rate was set at 1.5 L/min. Pure water was used as the slurry, and dressing was performed for 10 minutes. A SEM photograph of the polishing surface of the obtained reference polishing pad is shown in FIG.

Polishing was performed using the dressed reference polishing pad and using the test polished sample. Since the polishing speed was not sufficient, the dressing process and the pre-polishing of the test sample were alternately performed, and the target polishing speed was reached at the 25th time of the dressing process. Also, when the reference polishing pad was used, the number of scratches was 3 and the number of microscratches was 25, confirming that there were few polishing scratches (scratches).

Sa of the polishing surface of the reference polishing pad at this time was 4.7, Spc was 490, and Spd was 4,800.

(Example 1)
A polishing pad obtained by the same manufacturing method as the reference polishing pad was subjected to no dressing treatment, using #240 grit paper, at a paper peripheral speed of 500 m/ml and a platen speed of 1 m/min. A polishing pad A was obtained by performing buffing so that the machining allowance was 50 μm. Sa, Spc, and Spd on the surface of the polishing surface of polishing pad A (after buffing) were each measured four times and averaged. The respective results were Sa of 4.3, Spc of 420 and Spd of 3600. A SEM photograph of the polishing surface of the obtained polishing pad of Example 1 is shown in FIG.
When a polishing test was conducted using this polishing pad A, a sufficient polishing rate was obtained even without performing the dressing treatment. In other words, the break-in time could be shortened. Furthermore, the number of scratches was 2, and the number of microscratches was 18, confirming that there were few polishing flaws (scratches).

(Example 2)
A polishing pad obtained by the same manufacturing method as the reference polishing pad was subjected to no dressing treatment, using #180 grit paper, at a paper peripheral speed of 500 m/ml and a platen speed of 1 m/min. A polishing pad B was obtained by buffing. Sa, Spc, and Spd on the surface of the polishing surface of polishing pad B (after buffing) were each measured four times, and the average value was taken. The respective results were Sa of 5.4, Spc of 480 and Spd of 4500. A SEM photograph of the polishing surface of the obtained polishing pad of Example 2 is shown in FIG.
When a polishing test was conducted using this polishing pad B, a sufficient polishing rate was obtained even without performing the dressing treatment. In other words, the break-in time could be shortened. Furthermore, the number of scratches was 4 and the number of micro-scratches was 26, confirming that there were few polishing flaws (scratches).

(Comparative example 1)
A polishing pad obtained by the same manufacturing method as the reference polishing pad was buffed using #120 grit paper at a paper peripheral speed of 1000 m/ml and a platen speed of 1 m/min. , to obtain a polishing pad C. Sa, Spc, and Spd on the surface of the polishing surface of polishing pad C (after buffing) were measured four times, and averaged. The respective results were Sa of 6.3, Spc of 800 and Spd of 8200. A SEM photograph of the polishing surface of the obtained polishing pad of Comparative Example 1 is shown in FIG.
When a polishing test was conducted using this polishing pad C, the break-in time could be shortened, but the number of scratches was 9 and the number of micro-scratches was 42. It was confirmed that there were many scratches.

Comparing the reference polishing pad, which has a sufficient polishing rate and few defects, with the polishing pad C of Comparative Example 1, the polishing pad is excellent from the viewpoint of defects, although the Ra values are almost the same. It was hard to say. It is considered that the values of Sa, Spc, Spd, etc. were not within the predetermined range.
On the other hand, polishing pads A and B were able to shorten the break-in time and had few defects because of Ra, Sa, and Spc, which were the same as those of the reference polishing pads subjected to dressing treatment. It is thought that Spd was also equivalent.

Claims (2)

In a polishing pad having a polishing layer for polishing an object to be polished, it represents the average absolute value of the difference in height of each point with respect to the average surface of the polishing surface of the polishing layer in an undressed state. The arithmetic mean height (Sa) is 4 μm or more and 8 μm or less , and the arithmetic mean curvature (Spc) of the peak points, which is the average of the principal curvatures of the peak points of the polished surface, is 300 (1/mm) or more and 500 (1 / mm) or less , and the peak density (Spd) representing the number of peak points per unit area of the polished surface is 3000 (1/mm ² ) or more and 5000 (1/mm ² ) or less. A buffed polishing pad, characterized by: 2. The method for producing a polishing pad according to claim 1, comprising a step of performing buffing under conditions in which the ratio of the peripheral speed of the paper to the speed of the platen (paper peripheral speed/platen speed) is 50-750.

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