TWI910141B - Manufacturing method of grinding pad and grinding workpiece - Google Patents

Abstract

The abrasive pad of the present invention has a polyurethane sheet as an abrasive layer, and the ratio of the storage modulus _E'B40 to the storage modulus _E'T40 of the polyurethane sheet ( _E'B40 / _E'T40 ) is 0.60 to 1.60. The storage modulus _E'T40 is the storage modulus at 40°C under dynamic viscoelasticity measurement performed at a frequency of 1.6 Hz in tensile mode, and the storage modulus _E'B40 is the storage modulus at 40°C under dynamic viscoelasticity measurement performed at a frequency of 1.6 Hz in bending mode.

Description

Manufacturing method of grinding pad and grinding workpiece

This invention relates to a method for manufacturing an abrasive pad and an abrasive workpiece.

Chemical-mechanical grinding is performed on the surface (processed surface) of materials such as semiconductor components and electronic parts, especially thin substrates such as Si substrates (silicon wafers), hard disk substrates, glass or LCD (liquid crystal display) substrates (the objects to be ground), using abrasive paste and abrasive pads.

It is known that grinding pads used in this type of grinding process, for example, use grinding pads with a grinding layer having an E' ratio of approximately 1 to 3.6 at 30°C to 90°C to reduce depressions (Patent 1). Also, grinding pads using a polymer material as the grinding layer are used to combine planarization performance and a low defect rate. The aforementioned polymer material has a porosity of 0.1% by volume, and a KEL energy loss coefficient of 385 to 750 l/Pa at 40°C and 1 rad/sec, and an elastic modulus E' of 100 to 400 MPa at 40°C and 1 rad/sec (Patent 2). Prior Art Documents Patent Documents

Patent Document 1: Japanese Patent Application Publication No. 2004-507076 Patent Document 2: Japanese Patent Application Publication No. 2005-136400

[The problem that the invention aims to solve]

However, it is known that when using the polishing pads described in the aforementioned patent documents 1 and 2, the surface quality of the polished object is not high, for example, scratches may occur.

This invention addresses the aforementioned problems, aiming to provide an abrasive pad and a method for manufacturing abrasive workpieces that reduce scratches. [Technical Means for Solving the Problem]

The inventors conducted extensive research to solve the above problems and discovered that by using polyurethane sheets whose storage modulus values are within a specific range when performing dynamic viscoelasticity measurements in tensile and bending modes as a polishing layer, the above problems can be solved, thus completing the present invention.

That is, the present invention is as follows. [1] An abrasive pad having a polyurethane sheet as an abrasive layer, wherein the ratio of the storage modulus _E'B40 to the storage modulus _E'T40 of the polyurethane sheet ( _E'B40 / _E'T40 ) is 0.60 to 1.60, wherein the storage modulus _E'T40 is the storage modulus at 40°C under dynamic viscoelasticity measurement performed under tensile mode conditions at a frequency of 1.6 Hz, and the storage modulus _E'B40 is the storage modulus at 40°C under dynamic viscoelasticity measurement performed under bending mode conditions at a frequency of 1.6 Hz. [2] The grinding pad described in [1] has a storage modulus _E'B40 of 1.50× ^10⁸ to 4.50× ^10⁸ Pa. [3] The grinding pad described in [1] or [2] has a storage modulus _E'T40 of 1.50× ^10⁸ to 4.50× ^10⁸ Pa. [4] The abrasive pad described in any of [1] to [3], wherein the ratio of the storage modulus _E'B30 to the storage modulus _E'B50 of the polyurethane sheet ( _E'B30 / _E'B50 ) is 1.00 to 2.60, wherein the storage modulus _E'B50 is the storage modulus at 50°C under dynamic viscoelasticity measurement performed under bending mode conditions at a frequency of 1.6 Hz, and the storage modulus _E'B30 is the storage modulus at 30°C under dynamic viscoelasticity measurement performed under bending mode conditions at a frequency of 1.6 Hz. [5] The abrasive pad described in any of [1] to [4], wherein the polyurethane sheet comprises polyurethane resin and hollow microparticles dispersed in the polyurethane resin. [6] The abrasive pad described in [5], wherein the average particle size of the hollow microparticles is 30 μm or less. [7] A method for manufacturing an abrasive workpiece, comprising a grinding step of grinding the workpiece using an abrasive pad described in any of [1] to [6] in the presence of an abrasive slurry. [Effects of the Invention]

According to the present invention, a method for manufacturing an abrasive pad and an abrasive workpiece that can reduce the generation of scratches can be provided.

The embodiments of the present invention (hereinafter referred to as "the embodiments") will be described in detail below, but the present invention is not limited thereto and various changes can be made without departing from its spirit.

[Abrasive Pad] The abrasive pad of this embodiment has a polyurethane sheet as an abrasive layer, and the ratio of the storage modulus _E'B40 to the storage modulus _E'T40 ( _E'B40 / _E'T40 ) of the polyurethane sheet is 0.60 to 1.60. The storage modulus _E'T40 is the storage modulus at 40°C under dynamic viscoelasticity measurement performed under tensile mode conditions at a frequency of 1.6 Hz, and the storage modulus _E'B40 is the storage modulus at 40°C under dynamic viscoelasticity measurement performed under bending mode conditions at a frequency of 1.6 Hz.

The storage modulus E' represents the elastic component exhibited by the substance being measured under the specified measurement conditions. Before grinding the workpiece using a grinding pad, a dressing process is performed to adjust the flatness and surface roughness of the grinding surface. During this dressing process, a force perpendicular to the grinding pad (grinding pressure) and a force rubbing the grinding pad relative to the grinding pad (rotational force) are applied. Furthermore, during the grinding step where the workpiece contacts the grinding pad, a force perpendicular to the workpiece (grinding pressure) and a force rubbing the grinding pad relative to the workpiece (rotational force) are applied. At this point, the abrasive pad, to which these two forces are applied, follows the dresser and the workpiece to some extent, thereby obtaining a polished surface with excellent quality. Therefore, in this embodiment, by specifying the ratio of the storage modulus E' obtained when performing dynamic viscoelasticity measurements in tensile and bending modes, the generation of scratches is suppressed. Furthermore, although the results of dynamic viscoelasticity measurements in tensile and bending modes may be substantially the same, they exhibit at least different behaviors on the abrasive pad.

From the perspective described above, in this embodiment, the ratio of storage modulus _E'B40 to storage modulus _E'T40 ( _E'B40 / _E'T40 ) is used as an indicator. Storage modulus _E'T40 is the storage modulus at 40°C under dynamic viscoelasticity testing conducted at a frequency of 1.6 Hz in tensile mode, and storage modulus _E'B40 is the storage modulus at 40°C under dynamic viscoelasticity testing conducted at a frequency of 1.6 Hz in bending mode. The ratio ( _E'B40 / _E'T40 ) is 0.60 to 1.60, preferably 0.70 to 1.40, more preferably 0.75 to 1.20, and even more preferably 0.80 to 1.00. By ensuring that the ratio ( _E'B40 / _E'T40 ) is within the aforementioned range, particularly _0.60 or higher, the polishing _pad can more effectively follow the dresser when subjected to vertical and horizontal forces, improving the condition of the polished surface and suppressing the formation of scratches. While there are no particular limitations on the reasons, it is believed that by ensuring that the tensile storage modulus responding to horizontal forces and the bending storage modulus responding to vertical forces to follow the surface of the workpiece are within the aforementioned range, the polishing pad can more effectively follow the dresser when subjected to vertical and horizontal forces. However, the reasons for suppressing the formation of scratches are not limited to the reasons described above.

Furthermore, _E'B40 is preferably 1.50 × ^10⁸ to 4.50 × ^10⁸ Pa, more preferably 1.75 × ^10⁸ to 4.10 × ^10⁸ Pa, and even more preferably 2.00 × ^10⁸ to 3.70 × ^10⁸ Pa. By placing _E'B40 within the above range, the following trend is observed: when subjected to a vertical force, the grinding pad follows the dresser more effectively, the condition of the grinding surface is improved, and the generation of scratches is further suppressed.

The _E'T40 is preferably 1.50 × ^10⁸ to 4.50 × ^10⁸ Pa, more preferably 2.00 × ^10⁸ to 4.20 × ^10⁸ Pa, and even more preferably 2.30 × ^10⁸ to 3.90 × ^10⁸ Pa. By placing _E'T40 within the above range, the following trend is observed: under horizontal force, the grinding pad follows the dresser more effectively, the condition of the grinding surface is improved, and the generation of scratches is further suppressed.

The temperature of the grinding pad in the grinding process is generally around 40°C. Therefore, in this embodiment, the ratio of the storage modulus of the bending mode to the tensile mode at 40°C is specified. Furthermore, in this case, the trend of the storage modulus of the bending mode can be further specified. Specifically, in the dynamic viscoelasticity test conducted under bending mode conditions at a frequency of 1.6 _Hz , the ratio ( _E'B30 / _E'B50 ) of the storage modulus _E'B30 at 30°C to the storage modulus E'B50 at 50°C is preferably 1.00 to 2.60, more preferably 1.20 to 2.30, and even more preferably 1.30 to 2.00. By keeping the ratio ( _E'B30 / _E'B50 ) within the aforementioned range, the rate of change of the storage modulus at 30–50°C is smaller, and near 40°C, the ratio of the storage modulus of the bending mode to the stretching mode ( _E'B40 / _E'T40 ) easily meets a specific range. Therefore, the following trend emerges in the polishing process: under vertical and horizontal forces, the polishing pad follows the dresser more effectively, the condition of the polished surface is improved, and the generation of scratches is further suppressed.

Furthermore, _E'B30 is preferably 2.50 × ^10⁸ to 5.50 × ^10⁸ Pa, more preferably 2.60 × ^10⁸ to 5.00 × ^10⁸ Pa, and even more preferably 2.70 × ^10⁸ to 4.50 × ^10⁸ Pa. Also, _E'B50 is preferably 1.00 × ^10⁸ to 3.50 × ^10⁸ Pa, more preferably 1.25 × ^10⁸ to 3.20 × ^10⁸ Pa, and even more preferably 1.50 × ^10⁸ to 2.90 × ^10⁸ Pa. By having _E'B30 and/or _E'B50 within the above ranges, there is a trend towards further suppression of scratch formation.

The dynamic viscoelasticity measurement of this embodiment can be carried out according to the conventional methods of bending and stretching modes. There are no particular restrictions on other conditions, and the measurement can be carried out using the conditions described in the embodiments.

(Polyurethane Sheet) Polyurethane sheet is used as the abrasive layer possessing the above-mentioned properties. There are no particular limitations on the polyurethane resin constituting the polyurethane sheet; examples include polyester-based polyurethane resins, polyether-based polyurethane resins, and polycarbonate-based polyurethane resins. There are no particular limitations on this polyurethane resin; it can be a reaction product of a polyurethane prepolymer and a hardener, and various known resins can be used. One type can be used alone, or two or more types can be used in combination.

(Carbamate Prepolymers) As carbamate prepolymers, there are no particular limitations; reactants of polyisocyanate compounds and polyol compounds, or commercially available carbamate prepolymers, can be used.

There are no particular restrictions on whether a compound is a polyisocyanate, as long as it contains two or more isocyanate groups within its molecule. Examples include: isophthalic diisocyanate, terephthalic diisocyanate, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, naphthalene-1,4-diisocyanate, diphenylmethane-4,4'-diisocyanate, 4,4'-methylene-bis(cyclohexyl)isocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, 3, 3'-Dimethyldiphenylmethane-4,4'-diisocyanate, phenyldimethyl-1,4-diisocyanate, 4,4'-diphenylpropane diisocyanate, trimethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylidene diisocyanate, 1,2-butylidene diisocyanate, 1,2-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, terephthalic diisothiocyanate, phenyldimethyl-1,4-diisothiocyanate, methinediisothiocyanate, etc.

Among them, 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, and diphenylmethane-4,4'-diisocyanate are preferred, and 2,6-toluene diisocyanate and 2,4-toluene diisocyanate are even more preferred. One polyisocyanate compound may be used alone, or two or more may be used in combination.

There are no particular restrictions on polyol compounds, as long as they contain two or more hydroxyl groups in their molecules. Examples include: diol compounds such as ethylene glycol, diethylene glycol, and butanediol; triol compounds; polyether polyol compounds such as polypropylene glycol and poly(oxytetramethylene) glycol; polyester polyol compounds such as the reaction product of ethylene glycol and adipic acid or the reaction product of butanediol and adipic acid; polycarbonate polyol compounds and polycaprolactone polyol compounds; and trifunctional propylene glycol with ethylene oxide addition.

Among them, poly(oxytetramethylene) glycol, polypropylene glycol, and diethylene glycol are preferred, with poly(oxytetramethylene) glycol being even more preferred. A single polyol compound may be used alone, or two or more may be used in combination.

Polyol compounds can also be used in combination with high molecular weight polyols such as poly(oxytetramethylene) glycol and polypropylene glycol, and low molecular weight polyols such as diethylene glycol. The number average molecular weight of the high molecular weight polyols is preferably 300–2000, more preferably 400–1750, and even more preferably 500–1500. Furthermore, the high molecular weight polyols can contain two or more compounds with different number average molecular weights.

The NCO equivalent of the urethane prepolymer is preferably 300–700, more preferably 350–600, and even more preferably 400–500. Furthermore, the "NCO equivalent" is calculated using the following formula, representing the molecular weight of each NCO group in the urethane prepolymer: "(mass parts of polyisocyanate compound + mass parts of polyol compound) / [(functional groups per molecule of polyisocyanate compound × mass parts of polyisocyanate compound / molecular weight of polyisocyanate compound) - (functional groups per molecule of polyol compound × mass parts of polyol compound / molecular weight of polyol compound)]".

(Hardening Agent) There are no particular limitations on the type of hardener; examples include polyamine compounds and polyol compounds. A single hardener can be used alone, or two or more can be used in combination.

As polyamine compounds, there are no particular limitations; examples include: ethylenediamine, propylenediamine, hexamethylenediamine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA), 4-methyl-2,6-bis(methylthio)-1,3-phenylenediamine, 2-methyl-4,6-bis(methylthio)-1,3-phenylenediamine, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 2, 2-bis[3-(isopropylamino)-4-hydroxyphenyl]propane, 2,2-bis[3-(1-methylpropylamino)-4-hydroxyphenyl]propane, 2,2-bis[3-(1-methylpentylamino)-4-hydroxyphenyl]propane, 2,2-bis(3,5-diamino-4-hydroxyphenyl)propane, 2,6-diamino-4-methylphenol, trimethyl ethyl bis-4-aminobenzoate, and polytetramethylene di-p-aminobenzoate, etc.

As polyol compounds, there are no particular limitations. Examples include: ethylene glycol, propylene glycol, diethylene glycol, 1,3-propanediol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyl-1,3-propanediol, tetraethylene glycol, etc. Methylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, 1,4-cyclohexanediol, neopentanediol, glycerol, trihydroxymethylpropane, trihydroxymethylethane, trihydroxymethylmethane, poly(oxytetramethylene) glycol, polyethylene glycol, and polypropylene glycol, etc.

Furthermore, polyamine compounds may contain hydroxyl groups. Examples of such amine compounds include 2-hydroxyethyl ethylenediamine, 2-hydroxyethyl propanediamine, di-2-hydroxyethyl ethylenediamine, di-2-hydroxyethyl propanediamine, 2-hydroxypropyl ethylenediamine, and di-2-hydroxypropyl ethylenediamine.

Among these, the polyamine compound is preferably a diamine compound, and more preferably 3,3'-dichloro-4,4'-diaminodiphenylmethane (MOCA). Commercially available MOCA products include, for example, PANDEX E (manufactured by DIC) and IHARACUAMINE MT (manufactured by Combination Chemicals). The hardener can be used alone or in combination with two or more.

The amount of hardener added is preferably 10 to 60 parts by weight, more preferably 20 to 50 parts by weight, and even more preferably 20 to 40 parts by weight, relative to 100 parts by weight of the urethane prepolymer.

The storage modulus of bending and stretching modes can be adjusted by the molecular weight (degree of polymerization) of the carbamate prepolymer or by the combination of the carbamate prepolymer and the hardener. From this perspective, for example, the R-value can be used as an indicator. The R-value is the equivalence ratio of active hydrogen groups (amine and hydroxyl groups) present in the hardener to the terminal isocyanate groups present in the isocyanate-containing compound of the carbamate prepolymer. A preferred R-value is 0.70–1.30, more preferably 0.75–1.20, further preferably 0.80–1.10, further preferably 0.80–1.00, and particularly preferably 0.85–0.95.

(Bubble) Furthermore, the polyurethane sheet is preferably a foamed polyurethane sheet containing bubbles. Moreover, the bubbles in the foamed polyurethane sheet can be classified according to their morphology into independent bubbles (multiple bubbles existing independently) and continuous bubbles (multiple bubbles connected by interconnecting holes). In this embodiment, the polyurethane sheet preferably contains independent bubbles, and more preferably is a polyurethane sheet comprising polyurethane resin and hollow microparticles dispersed within the polyurethane resin. By using hollow microparticles, there is a trend towards easily adjustable storage modulus for bending and stretching modes.

Polyurethane sheets containing independent bubbles can be manufactured using hollow microparticles that have an outer shell and a hollow interior. The hollow microparticles can be commercially available or synthesized by conventional methods.

There are no particular limitations on the material used as the outer shell of hollow microparticles. Examples include: polyvinyl alcohol, polyvinylpyrrolidone, poly(meth)acrylic acid, polyacrylamide, polyethylene glycol, polyhydroxyether acrylate, maleic acid copolymer, polyethylene oxide, polyurethane, poly(meth)acrylonitrile, polyvinylidene chloride, polyvinyl chloride, and organosilicone resins, as well as copolymers formed by combining two or more monomers constituting such resins. Furthermore, commercially available hollow microparticles include, for example, the Expancel series (a trade name manufactured by AkzoNobel) and Matsumoto Microsphere (a trade name manufactured by Matsumoto Oils & Fats Co., Ltd.), but are not limited to the above.

The shape of the hollow microparticles in the polyurethane sheet is not particularly limited; for example, they can be spherical or nearly spherical. The average particle size of the hollow microparticles is preferably 30 μm or less, more preferably 25 μm or less, further preferably 20 μm or less, further preferably 15 μm or less, and especially preferably 10 μm or less. Furthermore, the average particle size of the hollow microparticles is preferably 1 μm or more, more preferably 2 μm or more, and further preferably 4 μm or more. By using such hollow microparticles, the storage modulus of bending and stretching modes can also be adjusted. Moreover, the average particle size can be measured using a laser diffraction particle size distribution measuring device (e.g., Mastersizer 2000 manufactured by Spectris Inc.). By ensuring that the average particle size of the hollow microparticles falls within the aforementioned range, the impact of the size of the bubbles formed by the hollow microparticles on the storage modulus can be reduced, allowing the bending storage modulus and stretching storage modulus to be adjusted to the desired range. Furthermore, in this embodiment, the average particle size refers to the median diameter of the volumetric reference.

Furthermore, hollow microparticles include expanded and unexpanded types, with the unexpanded type being preferred. By using unexpanded hollow microparticles, the smaller diameter bubbles formed in the polyurethane sheet become dispersed, allowing the flexural and tensile storage moduli to be adjusted to the desired range.

Regarding the amount of hollow microparticles added, it is preferably 0.1 to 10 parts by weight, more preferably 1 to 5 parts by weight, and even more preferably 1 to 4 parts by weight relative to 100 parts by weight of the urethane prepolymer. By adjusting the amount of hollow microparticles added to the above range, the storage modulus of the bending and stretching modes can also be adjusted.

(Other Components) Furthermore, in addition to the components mentioned above, to the extent that the effects of this invention are not impaired, the previously used foaming agent and hollow microparticles may be used in combination, or a non-reactive gas may be blown into each component during the mixing steps described below. Examples of foaming agents include water and foaming agents with hydrocarbons having 5 or 6 carbon atoms as the main component. Examples of such hydrocarbons include chain hydrocarbons such as n-pentane and n-hexane; and alicyclic hydrocarbons such as cyclopentane and cyclohexane. In addition to the components mentioned above, known foam stabilizers, flame retardants, colorants, plasticizers, etc., may also be added.

(Manufacturing Method of Polyurethane Sheets) There are no particular limitations on the manufacturing method of polyurethane sheets. For example, a method comprising the following steps can be described: a reaction step in which a polyurethane prepolymer is reacted with a hardener in the presence of hollow microparticles to obtain a polyurethane resin block; and a forming step in which sheets are cut from the obtained polyurethane resin block. Each step is explained in detail below.

(Reaction Steps) In the reaction steps, the urethane prepolymer and hardener are fed into a mixer and stirred and mixed to carry out the reaction. Furthermore, when using hollow microparticles, a polyurethane resin block containing hollow microparticles can be obtained by mixing the urethane prepolymer, hardener, and hollow microparticles. The order of mixing the components is not particularly limited, but it is preferable to mix the urethane prepolymer and hollow microparticles first, followed by feeding the hardener into the mixer.

In this embodiment, from the viewpoint of adjusting the storage modulus of bending and stretching modes, it is ideal to reduce the diameter of the bubbles within the polyurethane sheet and, in the case of using hollow microparticles, the particle size of the hollow microparticles. Therefore, in the reaction between the polyurethane prepolymer and the hardener, it is preferable to mix under conditions where the hollow microparticles have not expanded.

As an example of such a method, the following method can be used: under relatively unheated conditions, hollow microparticles and urethane prepolymers are mixed in a first tank, and a hardener is mixed in a second tank. Then, the hollow microparticles and urethane prepolymers from the first tank and the hardener from the second tank are added to a mixer for mixing.

Regarding the relatively unheated conditions, more specifically, the temperature of the first liquid tank is preferably 30–80°C, more preferably 35–70°C, and even more preferably 40–65°C. This can suppress the expansion of hollow microparticles.

Next, the mixture prepared as described above is poured into a mold preheated to 30–100°C and heated to approximately 100–150°C for about 10 minutes to 5 hours to harden it, thereby forming a polyurethane resin block. During this process, the polyurethane prepolymer reacts with the hardener, and the mixture hardens with bubbles and/or hollow microparticles dispersed within the polyurethane resin. This results in a polyurethane resin block containing multiple generally spherical bubbles.

(Forming Steps) Subsequently, the obtained polyurethane resin block is cut into sheets to form polyurethane sheets. Openings are created on the surface of the sheets through slicing. To form openings on the surface of the abrasive layer with excellent wear resistance and minimal clogging, the sheets are cured at 30–150°C for approximately 1 hour to 24 hours.

For an abrasive layer having a polyurethane sheet obtained as described above, double-sided tape is then applied to the side of the abrasive layer opposite to the abrasive surface, and cut into a specific shape, preferably a circular plate, thereby completing the abrasive pad of this embodiment. There are no particular limitations on the double-sided tape; any double-sided tape known in the art can be selected and used.

Furthermore, the polishing pad of this embodiment can be a single-layer structure containing only the polishing layer, or it can be a multi-layer structure in which other layers (bottom layer, support layer) are attached to the side of the polishing layer opposite to the polishing surface. The characteristics of the other layers are not particularly limited. If a layer softer than the polishing layer is attached to the side of the polishing layer opposite to the polishing surface, the polishing flatness is further improved. On the other hand, if a layer harder than the polishing layer is attached to the side of the polishing layer opposite to the polishing surface, the polishing speed is further improved.

In cases involving multi-layered structures, pressure is applied as needed, and multiple layers are bonded and secured to each other using double-sided tape or adhesives. There are no particular restrictions on the double-sided tape or adhesive used; any type known in the art can be selected.

Furthermore, the abrasive pad of this embodiment can be ground on the front and/or back of the abrasive layer as needed, or grooved, embossed, or drilled on the front. It can also bond the substrate and/or adhesive layer to the abrasive layer and may have light-transmitting portions. There are no particular limitations on the grinding method; well-known methods can be used. Specifically, grinding using sandpaper can be an example. There are no particular limitations on the shape of the grooves and embossing; for example, grid patterns, concentric circles, and radial shapes can be used.

[Method for Manufacturing Abrasive Workpiece] The method for manufacturing abrasive workpiece according to this embodiment includes a grinding step in which the workpiece is ground using the aforementioned grinding pad in the presence of an abrasive slurry to obtain an abrasive workpiece. The grinding step can be a single grinding (coarse grinding), a fine grinding, or a combination of both. Preferably, the grinding pad of this embodiment is used for chemical-mechanical grinding. The following description uses chemical-mechanical grinding as an example to illustrate the method for manufacturing abrasive workpiece according to this embodiment, but the method for manufacturing abrasive workpiece according to this embodiment is not limited to this method.

In this manufacturing method, an abrasive paste is supplied, and the workpiece is pressed against the grinding pad by a retaining plate. Simultaneously, the retaining plate and the grinding plate rotate relative to each other, thereby using the grinding pad to perform chemical mechanical polishing (CMP) on the workpiece's surface. The retaining plate and the grinding plate can rotate at different speeds in the same direction, or they can rotate in different directions. Furthermore, the workpiece can move (rotate) inside the frame while being ground.

Depending on the material being ground or the grinding conditions, grinding slurries may contain water, chemical components such as oxidants (e.g., hydrogen peroxide ₎ , additives, and abrasive particles (e.g., SiC, _SiO2 , _Al2O3 , _CeO2 ).

Furthermore, the workpiece being polished is not particularly limited; examples include materials such as semiconductor devices and electronic components, especially thin substrates such as Si substrates (silicon wafers), hard disk substrates, glass, or LCD (liquid crystal display) substrates. The polishing process described in this embodiment is suitable for manufacturing semiconductor devices with oxide layers, copper, or other metal layers. [Example]

The present invention will now be described in more detail using embodiments and comparative examples. However, the present invention is not limited to the following embodiments.

[Example 1] To 100 parts of an aminocarbamate prepolymer with an NCO equivalent of 455, obtained by reacting 2,4-toluene diisocyanate, poly(oxytetramethylene) glycol (number average molecular weight 1000), poly(oxytetramethylene) glycol (number average molecular weight 650), and diethylene glycol, 2.7 parts (average particle size 8.5 μm) of unexpanded hollow microparticles containing isobutane gas in the shell portion and comprising an acrylonitrile-vinylidene chloride copolymer were added to obtain an aminocarbamate prepolymer mixture. The obtained aminocarbamate prepolymer mixture was added to a first liquid tank and kept at 60°C. Furthermore, separately from the first liquid tank, 25.8 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-o-chloroaniline) (MOCA) as a hardener were added to the second liquid tank and mixed at 120°C. This mixture was then subjected to depressurization and defoaming to obtain a molten hardener. Furthermore, the operating temperature was set as described above to suppress the expansion of hollow microparticles.

Next, liquids from the first and second liquid tanks are injected into each of the two injection ports of a mixer, and stirred to obtain a mixture. Then, the mixing ratio is adjusted so that the R value, representing the equivalent ratio of amine and hydroxyl groups present in the hardener to the terminal isocyanate groups present in the urethane prepolymer, is 0.90.

The resulting mixture was poured into a mold preheated to 80°C and hardened once at 80°C for 30 minutes. The resulting block was then removed from the mold and hardened a second time in an oven at 120°C for 4 hours to obtain a urethane resin block. The urethane resin block was cooled to 25°C and then heated again in an oven at 120°C for 5 hours, followed by slicing to obtain a foamed polyurethane sheet. Double-sided tape was attached to the back of the obtained polyurethane sheet for use as a grinding pad.

[Comparative Example 1] As Comparative Example 1, a grinding pad (product name: IC1000) manufactured by NITTA HAAS was used.

[Example 2] To 100 parts of an urethane prepolymer with an NCO equivalent of 420, obtained by reacting 2,4-toluene diisocyanate, poly(oxytetramethylene) glycol (number average molecular weight 1000), poly(oxytetramethylene) glycol (number average molecular weight 650), and diethylene glycol, 2.5 parts (average particle size 8.5 μm) of unexpanded hollow microparticles containing isobutane gas in the shell portion of the mixture and comprising an acrylonitrile-vinylidene chloride copolymer were added to obtain an urethane prepolymer mixture. The obtained urethane prepolymer mixture was added to a first liquid tank and kept at 60°C. Furthermore, separately from the first liquid tank, 28.3 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-orthochloroaniline) (MOCA) as a hardener were added to the second liquid tank and mixed at 120°C. Depressurization and defoaming were then performed to obtain a molten hardener. Furthermore, the above-mentioned operating temperature was set to suppress the expansion of hollow microparticles. Except for the above operations, the grinding pad of Example 2 was manufactured in the same manner as in Example 1.

[Example 3] To 100 parts of an urethane prepolymer with an NCO equivalent of 420, obtained by reacting 2,4-toluene diisocyanate, poly(oxytetramethylene) glycol (number average molecular weight 1000), poly(oxytetramethylene) glycol (number average molecular weight 650), and diethylene glycol, 4.9 parts (average particle size 5.3 μm) of unexpanded hollow microparticles containing isobutane gas in the shell portion of the mixture and comprising an acrylonitrile-vinylidene chloride copolymer were added to obtain an urethane prepolymer mixture. The obtained urethane prepolymer mixture was added to a first liquid tank and kept at 60°C. Furthermore, separately from the first liquid tank, 27.8 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-orthochloroaniline) (MOCA) as a hardener were added to the second liquid tank and mixed at 120°C. Depressurization and defoaming were then performed to obtain a molten hardener. Furthermore, the above-mentioned operating temperature was set to suppress the expansion of hollow microparticles. Except for the above operations, the grinding pad of Example 3 was manufactured in the same manner as in Example 1.

[Example 4] To 100 parts of an aminocarbamate prepolymer with an NCO equivalent of 420, obtained by reacting 2,4-toluene diisocyanate, poly(oxytetramethylene) glycol (number average molecular weight 650), and diethylene glycol, 2.8 parts (average particle size 6.9 μm) of unexpanded hollow microparticles containing isobutane gas in the shell portion and comprising an acrylonitrile-vinylidene chloride copolymer were added to obtain an aminocarbamate prepolymer mixture. The obtained aminocarbamate prepolymer mixture was added to a first liquid tank and kept at 60°C. Furthermore, separately from the first liquid tank, 28.1 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-o-chloroaniline) (MOCA) as a hardener were added to the second liquid tank and mixed at 120°C. Depressurization and defoaming were then performed to obtain a molten hardener. Furthermore, the above-mentioned operating temperature was set to suppress the expansion of hollow microparticles. Except for the above operations, the grinding pad of Example 4 was manufactured in the same manner as in Example 1.

[Example 5] To 100 parts of an aminocarbamate prepolymer with an NCO equivalent of 440, obtained by reacting 2,4-toluene diisocyanate, poly(oxytetramethylene) glycol (number average molecular weight 650), and diethylene glycol, 2.9 parts (average particle size 6.9 μm) of unexpanded hollow microparticles containing isobutane gas in the shell portion and comprising an acrylonitrile-vinylidene chloride copolymer were added to obtain an aminocarbamate prepolymer mixture. The obtained aminocarbamate prepolymer mixture was added to a first liquid tank and kept at 60°C. Furthermore, separately from the first liquid tank, 26.7 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-orthochloroaniline) (MOCA) as a hardener were added to the second liquid tank and mixed at 120°C. Depressurization and defoaming were then performed to obtain a molten hardener. Furthermore, the above-mentioned operating temperature was set to suppress the expansion of hollow microparticles. Except for the above operations, the grinding pad of Example 5 was manufactured in the same manner as in Example 1.

[Example 6] To 100 parts of an NCO equivalent 500 urethane prepolymer obtained by reacting 2,4-toluene diisocyanate, polypropylene glycol (number average molecular weight 100), and diethylene glycol, 2.5 parts (average particle size 20 μm) of unexpanded hollow microparticles containing isobutane gas in the shell portion and comprising an acrylonitrile-vinylidene chloride copolymer in the shell were added to obtain an urethane prepolymer mixture. The obtained urethane prepolymer mixture was added to a first liquid tank and kept at 60°C. Furthermore, separately from the first liquid tank, 23.1 parts of 3,3'-dichloro-4,4'-diaminodiphenylmethane (methylene bis-orthochloroaniline) (MOCA) as a hardener were added to the second liquid tank and mixed at 120°C. Depressurization and defoaming were then performed to obtain a molten hardener. Furthermore, the above-mentioned operating temperature was set to suppress the expansion of hollow microparticles. Except for the above operations, the grinding pad of Example 6 was manufactured in the same manner as in Example 1.

[Dynamic Viscoelasticity Measurement] (Tension Mode) The dynamic viscoelasticity of polyurethane sheets was measured under the following conditions. Polyurethane sheets dried for 40 hours in a constant temperature and humidity bath at 23°C (±2°C) and 50% (±5%) were used as samples. The dynamic viscoelasticity was measured in tension mode under normal atmospheric conditions (dry condition). The measurement conditions for tension mode are shown below. (Test Conditions) Testing Apparatus: RSA3 (TA Instruments) Sample: 4 cm (L) × 0.5 cm (W) × 0.125 cm (H) Test Length: 1 cm Sample Pretreatment: 40 hours at 23°C and 50% relative humidity Test Mode: Tensile Frequency: 1.6 Hz (10 rad/sec) Temperature Range: 25–60°C Heating Rate: 1.5°C/min Strain Range: 0.10% Initial Load: 148 g Measurement Interval: 2 points/°C

(Bending Mode) Furthermore, the same sample was used to perform dynamic viscoelasticity measurements in the bending mode. The measurement conditions for the bending mode are as follows: (Measurement Conditions) Measurement Apparatus: RSA3 (TA Instruments) Sample: 5 cm (L) × 0.5 cm (W) × 0.125 cm (H) Test Length: - Sample Pretreatment: Heated at 23°C and 50% relative humidity for 40 hours Test Mode: Bending Frequency: 1.6 Hz (10 rad/sec) Temperature Range: 25–60°C Heating Rate: 1.5°C/min Strain Range: 0.10% Initial Load: - Measurement Interval: 2 points/°C

Figures 1 and 2 show the storage moduli of the stretching and bending modes of Embodiment 1 and Comparative Example 1.

[Surface Quality Confirmation Test] A polishing pad was placed at a specific position on the polishing apparatus using double-sided tape containing an acrylic adhesive, and a Cu film substrate was polished under the following conditions. (Grinding Conditions) Grinding Machine: F-REX300 (Ebara Seisakusho) Grinding Disc: A188 (3M) Speed: (Plate) 70 rpm, (Top Ring) 71 rpm Grinding Pressure: 3.5 psi Abrasive Temperature: 20℃ Abrasive Dispensing Rate: 200 ml/min Abrasive: PLANERLITE7000 (Fujimi Corporation) Workpiece: Cu film substrate Grinding Time: 60 seconds Pad Breakage: 35 N for 10 minutes Adjustment: Ex-situ, 35 N, 4 scans

For the 11th to 51st pieces after the above-mentioned grinding process, the number of point-like grinding damage (micro-scratches) larger than 155 nm on the ground surface was visually confirmed using an eDR5210 (manufactured by KLA-Tencor) ReviewSEM, and the average value was obtained. Based on the confirmation results of the scratches, the surface quality was evaluated.

[Table 1] Implementation Example 1 Comparative example 1 Implementation Example 2 Implementation Example 3 Implementation Example 4 Implementation Example 5 Implementation Example 6 Curved mode Storage Module [Pa] E' _{B 30} 2.93E+08 2.43E+08 4.17E+08 4.13E+08 3.53E+08 4.26E+08 2.63E+08 E' _{B 40} 2.23E+08 1.53E+08 3.32E+08 3.39E+08 2.73E+08 3.2E+08 1.61E+08 E' _{B 50} 1.72E+08 9.00E+07 2.63E+08 2.71E+08 2.12E+08 2.33E+08 1.02E+08 Stretch mode Storage Module [Pa] _{E'T 40} 2.54E+08 2.92E+08 3.81E+08 3.82E+08 3.15E+08 3.35E+08 1.66E+08 (E' _B30 / E' _B50 ) 1.70 2.70 1.58 1.52 1.67 1.83 2.57 (E' _B40 / E' _T40 ) 0.88 0.52 0.87 0.89 0.87 0.96 0.97 Scratch evaluation 4 9 5 3 4 3 3 [Industrial Applicability]

The polishing pad of this invention is used for polishing optical materials, semiconductor devices, hard disk substrates, etc. It is particularly suitable for polishing devices with oxide layers, copper and other metal layers formed on semiconductor wafers, and has industrial applicability.

Figure 1 shows the results of the dynamic viscoelasticity measurement in Example 1. Figure 2 shows the results of the dynamic viscoelasticity measurement in Comparative Example 1.

Claims (5)

An abrasive pad comprising a polyurethane sheet as an abrasive layer, wherein the polyurethane sheet comprises a polyurethane resin and hollow microparticles dispersed in the polyurethane resin, the hollow microparticles having an average particle size of 5.3–20 μm; the polyurethane resin is obtained by reacting a prepolymer with a curing agent; the prepolymer comprises only 2,4-toluene diisocyanate, poly(oxytetramethylene) glycol, and diethylene glycol; the curing agent comprises only 3,3'-dichloro-4,4'-diaminodiphenylmethane; and the ratio of the storage modulus _E'B40 to the storage modulus _E'T40 of the polyurethane sheet ( _E'B40 / _E'T40) is specified. The storage modulus is 0.60 to 1.60. The storage modulus _E'T40 is the storage modulus at 40°C under dynamic viscoelasticity measurement performed under tensile mode conditions at a frequency of 1.6 Hz. The storage modulus _E'B40 is the storage modulus at 40°C under dynamic viscoelasticity measurement performed under bending mode conditions at a frequency of 1.6 Hz. For example, the grinding pad in claim 1, wherein the storage modulus _E'B40 is 1.50× ^10⁸ to 4.50× ^10⁸ Pa. For example, the grinding pad in claim 1, wherein the storage modulus _E'T40 is 1.50× ^10⁸ to 4.50× ^10⁸ Pa. For example, in the abrasive pad of claim 1, the ratio of the storage modulus _E'B30 to the storage modulus _E'B50 of the polyurethane sheet ( _E'B30 / _E'B50 ) is 1.00 to 2.60. The storage modulus _E'B50 is the storage modulus at 50°C under dynamic viscoelasticity measurement performed at a frequency of 1.6 Hz in bending mode, and the storage modulus _E'B30 is the storage modulus at 30°C under dynamic viscoelasticity measurement performed at a frequency of 1.6 Hz in bending mode. A method for manufacturing an abrasive workpiece includes a grinding step of grinding the workpiece in the presence of an abrasive paste using an abrasive pad as described in any of claims 1 to 4.