JP6859056B2 - Polishing pad and its manufacturing method - Google Patents

Description

The present invention relates to a polishing pad and a method for manufacturing the polishing pad. In particular, the present invention relates to a polishing pad for a chemical mechanical polishing method (CMP) of a semiconductor device and a method for manufacturing the same.

Since the surface of materials such as silicon, hard disks, mother glass for liquid crystal displays, and semiconductor devices is required to be flat, free abrasive grain polishing using a polishing pad is performed. The free abrasive grain method is a method of polishing the machined surface of the object to be polished while supplying a slurry (polishing liquid) containing abrasive grains between the polishing pad and the object to be polished.

Polishing pads are roughly classified into hard and soft, and the mainstream is the dry method in which urethane prepolymer is formed by chain elongation for hard, and the wet film formation method in which urethane resin solution is solidified and molded in a coagulation bath and dried for soft. is there.
A hard polishing pad (dry polishing pad) is necessary to ensure the flatness of the substrate, but since it is hard, defects such as scratches increase. Therefore, there are an increasing number of cases where a soft polishing pad (wet polishing pad) that is less likely to cause defects such as scratches is used mainly in the finishing polishing process (Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-148802

However, the defects of the object to be polished include not only concave defects due to scratches and the like, but also convex defects due to adhesion of organic residues and pad debris generated during polishing to the object to be polished. Since the conventional soft polishing pad is soft, it can suppress concave defects such as scratches, but it is inferior in suppressing the convex defects and sufficiently suppresses defects generated in the object to be polished after polishing. I couldn't. Therefore, there is a high demand for a polishing pad that can improve the problem of convex defects due to the adhesion of organic residues and pad debris.

The present invention has been made in view of the above points, and an object of the present invention is to provide a polishing pad in which organic residue does not easily adhere to the surface of the object to be polished even if the object to be polished is polished. Another object of the present invention is to provide a polishing pad in which pad dust does not easily adhere to the surface of the object to be polished even if the object to be polished is polished.

As a result of diligent efforts, the present inventor has found that the adhesion of the organic residue to the object to be polished is related to the hardness component contained in the polyurethane resin sheet, and the amount of the hardness component contained in the polyurethane resin sheet is constant. It has been found that a polishing pad capable of remarkably reducing the amount of the organic residue adhering to the object to be polished can be obtained by suppressing the following. Further, the present inventor has found that the hardness component contained in the polyurethane resin sheet is mainly brought about by the coagulating liquid used for wet coagulation, and by using the coagulating liquid having a small hardness component concentration, polyurethane It has been found that it is possible to easily manufacture a polishing pad in which the amount of hardness components contained in the resin sheet is suppressed to a certain level or less and the amount of organic residue adhering to the object to be polished is remarkably reduced.
That is, the present invention provides the following.

<1> A polishing pad containing a wet-deposited polyurethane resin sheet.
The polyurethane resin sheet has a polished surface, and the amount of the hardness component which is a value obtained by converting the amount of calcium and magnesium derived from the calcium salt and the magnesium salt contained in the polyurethane resin sheet into the amount of calcium carbonate in the same molar amount. The polishing pad, which is 100 mg or less per 1 kg of the polyurethane resin sheet.
<2> The polishing pad according to <1>, wherein the polyurethane resin sheet contains a polyurethane resin having a 100% modulus of 1 to 20 MPa.
<3><1> or <2>, wherein the polyurethane resin sheet contains a filler selected from the group consisting of carbon black and silica in a ratio of 0.1 to 30 parts by mass with respect to 100 parts by mass of the polyurethane resin. Polishing pad described in.
<4> The value obtained by converting the amount of calcium derived from the calcium salt contained in the polyurethane resin sheet into the amount of calcium carbonate in the same mole is 70.0 mg or less per 1 kg of the polyurethane resin sheet, <1> to <3>. The polishing pad described in any of.
<5> The value obtained by converting the amount of magnesium derived from the magnesium salt contained in the polyurethane resin sheet into the amount of calcium carbonate in the same molar amount is 35.0 mg or less per 1 kg of the polyurethane resin sheet, <1> to <4>. The polishing pad described in any of.
<6> The polishing pad according to any one of <1> to <5> for polishing an object to be polished using a slurry containing an anionic surfactant.
<7> A step of preparing a polyurethane resin-containing solution containing a polyurethane resin and a solvent, and a step of immersing the polyurethane resin-containing solution in a coagulating solution to coagulate the polyurethane resin.
Including
The hardness component concentration, which is a value obtained by converting the concentration of calcium and magnesium derived from the calcium salt and magnesium salt contained in the coagulation liquid into the concentration of calcium carbonate in the same molar amount, is 60.0 mg / L or less, <1> to < The method for manufacturing a polishing pad according to any one of 6>.
<8> The production method according to <7>, wherein the polyurethane resin-containing solution contains 0 to 15 parts by mass of an anionic surfactant with respect to 100 parts by mass of the polyurethane resin.
<9> The polyurethane resin-containing solution contains 0.1 to 30 parts by mass of at least one filler selected from the group consisting of carbon black and silica with respect to 100 parts by mass of the polyurethane resin. <7> Alternatively, the production method according to <8>.

According to the present invention, it is possible to provide a polishing pad capable of significantly reducing the amount of organic residue adhering to an object to be polished. Further, in the polishing pad of the present invention, even if the object to be polished is polished, the pad dust does not easily adhere to the object to be polished. Therefore, defects (defects) that occur in the object to be polished such as a semiconductor device can be significantly reduced.

<< Polishing pad >>
The polishing pad of the present invention is a polishing pad containing a wet-deposited polyurethane resin sheet, and the polyurethane resin sheet has a polished surface and is derived from a calcium salt and a magnesium salt contained in the polyurethane resin sheet. The amount of the hardness component, which is a value obtained by converting the amount of calcium and magnesium into the amount of calcium carbonate in the same molar amount, is 100 mg or less per 1 kg of the polyurethane resin sheet.

<Polyurethane resin sheet>
In the present specification and claims, the wet-deposited polyurethane resin sheet is formed by wet-solidifying a solution containing a polyurethane resin and a solvent applied on a film-forming substrate by a wet film-forming method. A resin sheet. The wet-deposited polyurethane resin sheet has a plurality of tear-shaped bubbles. The teardrop-shaped bubble is a concept that means the bubble shape (having anisotropy and having a structure having a large diameter from the polished surface to the bottom of the polishing pad) contained in the molded body formed by the wet method. It is used to distinguish from the usual bubble shape (isotropic, spherical, elliptical, or a shape close to these) existing in the molded product formed by the dry film forming method. Therefore, the expression "wet-deposited polyurethane resin sheet" can also be expressed as "polyurethane resin sheet having a plurality of tear-shaped bubbles".
The polyurethane resin sheet of the present invention has a polished surface for polishing an object to be polished.

In the present specification, the pad waste refers to the material generated by tearing the polyurethane resin sheet due to friction between the polyurethane resin sheet and the object to be polished during polishing.
In the present specification, the organic residue refers to a convex organic substance other than pad scraps and abrasive grains found on the object to be polished after polishing. Examples of the organic residue include foreign substances such as soap scum derived from components such as surfactants contained in the polishing pad, and foreign substances such as soap scum derived from components in the slurry.

<Amount of hardness component>
In the present specification and claims, the hardness component refers to calcium derived from a calcium salt and magnesium derived from a magnesium salt.
In the present specification and the scope of patent claims, calcium derived from calcium salt is a concept used to distinguish it from a metal composed of calcium alone, and calcium salts such as calcium oxide, calcium acetate, calcium carbonate, and calcium sulfate are used. It means the constituent calcium (calcium ion).
In the present specification and the scope of patent claims, magnesium derived from magnesium salt is a concept used to distinguish it from a metal composed of magnesium alone, and constitutes magnesium salts such as magnesium oxide, magnesium acetate, magnesium carbonate, and magnesium sulfate. It means magnesium (magnesium ion).
In the polishing pad of the present invention, the value (hardness component amount) obtained by converting the amount (total amount) of calcium salt and magnesium salt-derived calcium and magnesium contained in the polyurethane resin sheet into the amount of calcium carbonate in the same molar amount is polyurethane. It is 100 mg or less per 1 kg of the resin sheet.

In the present specification and the scope of patent claims, the hardness component amount is the amount of calcium derived from calcium salt and magnesium derived from magnesium salt, which is the same as the total amount of calcium and magnesium, as in the method of calculating the hardness of water. It means the value converted into the amount of calcium carbonate of, and is calculated by the formula (1) below.
Hardness component amount (mg / kg) = Ca content (mg / kg) x 2.496 + Mg content (mg / kg) x 4.119 ... (1)
The numerical value "2.496" in the above formula is a value calculated by the molecular weight of calcium carbonate / the molecular weight of calcium, and the numerical value "4.119" is calculated by the molecular weight of calcium carbonate / the molecular weight of magnesium. The value.

The amount of the hardness component, which is a value obtained by converting the amount of calcium and magnesium derived from the calcium salt and magnesium salt contained in the polyurethane resin sheet into the amount of calcium carbonate in the same molar amount, is preferably 80 mg / kg or less, preferably 70 mg / kg. It is more preferably kg or less, even more preferably 60 mg / kg or less, even more preferably 50 mg / kg or less, and even more preferably 40 mg / kg or less. The lower limit is not particularly limited, and the amount of hardness component may be 0 mg / kg or more, 1.0 mg / kg or more, 5.0 mg / kg or more, or 10 mg / kg. It may be the above. When the amount of the hardness component is within the above range, the adhesion of the organic residue to the object to be polished can be sufficiently suppressed.
In the present invention, the reason why the amount of the hardness component affects the amount of the organic residue adhering to the object to be polished is not necessarily clear, but when the hardness component is present in the polyurethane resin sheet, the hardness component is the interface in the wet polishing pad. It is presumed that this is because it binds to an activator or a surfactant in a slurry to form something like soap residue (a type of organic residue) that is insoluble in water and has viscosity. As the amount of the soap scum adhering to the object to be polished increases, the convex defects of the object to be polished increase.
Since the polishing pad of the present invention has a small amount of hardness components, it is speculated that the formation of soap scum is suppressed, and thus the amount of organic residue adhering to the object to be polished can be reduced.

In the polishing pad of the present invention, the total amount of calcium salt and calcium and magnesium derived from the magnesium salt contained in the polyurethane resin sheet ^{is preferably 1.0 × 10 -3} mol or less per 1 kg of the polyurethane resin sheet, preferably 8 more preferably .0 × is 10 ^-4 mol / kg or less, even more preferably at most 7.0 × 10 ^-4 mol / kg, it is 6.0 × 10 ^-4 mol / kg or less Is even more preferably 5.0 × 10 ^-4 mol / kg or less, and even more preferably 4.0 × 10 ^-4 mol / kg or less. The lower limit is not particularly limited, and the total amount of calcium and magnesium derived from the calcium salt and the magnesium salt may be 0 mol / kg or more, or 0.1 × 10 ^-4 mol / kg or more. It may be 0.5 × 10 ^-4 mol / kg or more, or 1.0 × 10 ^-4 mol / kg or more. When the total amount of calcium and magnesium derived from the calcium salt and the magnesium salt is within the above range, the amount of organic residue adhering to the object to be polished can be reduced.

In the polishing pad of the present invention, the value obtained by converting the amount of calcium derived from the calcium salt contained in the polyurethane resin sheet into the amount of calcium carbonate in the same mole is preferably 70.0 mg or less per 1 kg of the polyurethane resin sheet. The value obtained by converting the amount of calcium into the amount of calcium carbonate in the same mole is more preferably 60.0 mg / kg or less, further preferably 50.0 mg / kg or less, and 40.0 mg / kg or less. It is even more preferably 30.0 mg / kg or less, and even more preferably 20.0 mg / kg or less. The lower limit is not particularly limited, and for example, the amount of calcium may be 0 mg / kg or more, 0.1 mg / kg or more, 0.5 mg / kg or more, and 1 It may be 0.0 mg / kg or more.
Further, in the polishing pad of the present invention, the amount of calcium derived from the calcium salt contained in the polyurethane resin sheet ^{is preferably 7.0 × 10 -4} mol or less per 1 kg of the polyurethane resin sheet. The amount of calcium ^{is more preferably 6.0 × 10 -4} mol / kg or less, even more preferably 5.0 × 10 ^-4 mol / kg or less, 4.0 × 10 ^-4 mol / kg or less. It is even more preferably less than / kg, even more preferably 3.0 × 10 ^-4 mol / kg or less, and even more preferably 2.0 × 10 ^-4 mol / kg or less. The lower limit is not particularly limited, and for example, the amount of calcium may be 0 mol / kg or more, 0.1 × 10 ^-5 mol / kg or more, and 0.5 × 10 ^-5 mol / kg or more. It may be / kg or more, and may be 1.0 × 10 ^{-5 mol / kg or more.}

In the polishing pad of the present invention, the value obtained by converting the amount of magnesium derived from the magnesium salt contained in the polyurethane resin sheet into the amount of calcium carbonate in the same mole is preferably 35.0 mg or less per 1 kg of the polyurethane resin sheet. The value obtained by converting the amount of magnesium into the amount of calcium carbonate in the same mole is more preferably 30.0 mg / kg or less, further preferably 25.0 mg / kg or less, and 20.0 mg / kg or less. It is even more preferably 15.0 mg / kg or less, and even more preferably 10.0 mg / kg or less. The lower limit is not particularly limited, and for example, the amount of magnesium may be 0 mg / kg or more, 0.1 mg / kg or more, 0.3 mg / kg or more, and 0. It may be 5.5 mg / kg or more.
Further, in the polishing pad of the present invention, the amount of magnesium derived from the magnesium salt contained in the polyurethane resin sheet ^{is preferably 3.5 × 10 -4} mol or less per 1 kg of the polyurethane resin sheet. The amount of magnesium ^{is even more preferably 3.0 × 10 -4} mol / or less, even more preferably 2.5 × 10 ^-4 mol / kg or less, and 2.0 × 10 ^-4 mol / kg. It is even more preferably kg or less, even more preferably 1.5 × 10 ^-4 mol / kg or less, and even more preferably 1.0 × 10 ^-4 mol / kg or less. The lower limit is not particularly limited, and for example, the amount of magnesium may be 0 mol / kg or more, 0.1 × 10 ^-5 mol / kg or more, and 0.3 × 10 ^-5 mol / kg or more. It may be / kg or more, and may be 0.5 × 10 ^{-5 mol / kg or more.}
The content of calcium and / or magnesium derived from calcium salt and / or magnesium salt in the polyurethane resin sheet, or calcium carbonate and / or magnesium derived from calcium salt and / or magnesium salt in the polyurethane resin sheet is the same molar amount of calcium carbonate. When the value converted to is within the above range, the amount of the organic residue adhering to the object to be polished can be sufficiently reduced.

<(A) Polyurethane resin>
The type of polyurethane resin used as the material for the polyurethane resin sheet in the polishing pad of the present invention is not particularly limited, and may be selected from various polyurethane resins according to the purpose of use. For example, polyester-based, polyether-based, or polycarbonate-based resins can be used.
Examples of the polyester-based resin include a polymer of a polyester polyol of ethylene glycol, butylene glycol and the like and adipic acid and the like, and a diisocyanate such as diphenylmethane-4,4'-diisocyanate. Examples of the polyether resin include a polymer of a polyether polyol such as polytetramethylene ether glycol and polypropylene glycol and an isocyanate such as diphenylmethane-4,4'-diisocyanate. Examples of the polycarbonate-based resin include a polymer of a polycarbonate polyol and an isocyanate such as diphenylmethane-4,4'-diisocyanate. These resins are available on the market, such as the product name "Chrisbon" manufactured by DIC Corporation, the product name "Samplen" manufactured by Sanyo Chemical Industries, Ltd., and the product name "Resamine" manufactured by Dainichi Seika Kogyo Co., Ltd. Available resins may be used, or resins having the desired properties may be produced by themselves.
Among these, polyester-based polyurethane resins, which are excellent in film formation stability and mechanical properties, are particularly preferable.

(100% modulus)
100% modulus (or resin modulus) is an index showing the hardness of the resin, and cuts off the load applied when the non-foamed resin sheet is stretched 100% (when stretched to twice the original length). It is the value divided by the area (hereinafter, may be referred to as resin modulus). The higher this value is, the harder the resin is.
The polyurethane resin preferably has a resin modulus of 1 to 20 MPa, more preferably 1 to 15 MPa, and even more preferably 3 to 10 MPa. When the resin modulus is within the above range, it is possible to obtain an effect that the object to be polished can be efficiently polished with high quality and an effect of reducing scratches due to the appropriate elastic characteristics required for the polishing pad.

<(B) Filler>
The polishing pad of the present invention may contain at least one filler selected from the group consisting of carbon black and silica in a polyurethane resin sheet.
At least one filler selected from the group consisting of carbon black and silica is preferably contained in the polyurethane resin sheet in an amount of 0.1 to 30 parts by mass, and 0.5 to 20 parts by mass, based on 100 parts by mass of the polyurethane resin. It is more preferably contained in parts by mass, further preferably 1 to 15 parts by mass, and even more preferably 2 to 10 parts by mass. When the ratio of the filler is within the above range, the polishing rate can be improved. In addition, the dressing property of the surface can be improved by imparting brittleness.

The particle size (dispersion diameter) of the filler such as carbon black and silica is preferably 20 to 800 nm, more preferably 50 to 500 nm, and even more preferably 100 to 400 nm. When the particle size is within the above range, the rigidity of the polyurethane resin sheet can be improved and scratches during polishing can be effectively suppressed, which is preferable.
The particle size of the filler can be measured using a dynamic light scattering method. More specifically, the particle size of the filler is the particle size in the dispersed state measured by using the dynamic light scattering method. Hereinafter, the particle size of the filler may be referred to as a dispersion diameter.

The polishing pad of the present invention may use a filler other than carbon black and / or silica in combination with carbon black and / or silica as long as the effect of the present invention is not impaired. Examples of the other filler include organic pigments such as azo pigments and inorganic pigments such as titanium oxide.

<(C) Other optional ingredients>
In addition to the above components, the polishing pad of the present invention contains a foaming aid, a cross-linking agent, a dispersant, a water repellent, a film-forming stabilizer, etc. in a polyurethane resin sheet within a range that does not impair the effects of the present invention. Additives may be included. Examples of the foaming aid include anionic surfactants, nonionic surfactants, and amphoteric surfactants. Among these, anionic surfactants are preferable, fatty acid-based anionic surfactants are more preferable, and sodium salts and potassium salts of higher fatty acids are preferable in order to form large foaming, for example, sodium lauryl sulfate and the like. , Sodium salts of monolong chain (preferably C8-C18, more preferably C10-C14) alkyl esters of sulfuric acid.

In the polishing pad of the present invention, the polished surface and / or the surface opposite to the polished surface of the polyurethane resin sheet may be ground (buffed). Among these, in the polishing pad of the present invention, it is preferable that the polished surface of the polyurethane resin sheet is ground. As a result, a large number of openings derived from microbubbles are present on the polished surface, and the polishing rate is improved by holding the slurry in the openings.
Further, in the polishing pad of the present invention, the polished surface of the polyurethane resin sheet may be grooved, embossed and / or hole-processed (punching). The polishing pad of the present invention may include a light transmitting portion.

<Other layers>
In the polishing pad of the present invention, the polyurethane resin sheet (polishing layer) may be bonded to another layer (lower layer, support layer) on the surface opposite to the surface (polishing surface) on which the object to be polished is to be polished. .. As the other layer, it is preferable to use a layer having a higher Shore A hardness than the polyurethane resin sheet. By providing another layer, the profile (surface and edge shape) of the substrate can be adjusted.
Examples of the other layer include non-woven fabric, plastic sheet, rubber, sponge and the like.
The thickness of the other layer is not particularly limited, but preferably 0.1 to 3 mm, more preferably about 0.15 to 2 mm is not subject to the mechanical restrictions of the polishing mechanism, and the polishing surface plate is determined. The influence of the board can be reduced sufficiently.

When the polishing pad forms a multi-layer structure, the plurality of layers may be bonded and fixed to each other by using double-sided tape or an adhesive while pressurizing and heating as necessary. The double-sided tape and adhesive used at this time are not particularly limited, and can be arbitrarily selected from the double-sided tapes and adhesives known in the art. It is also possible to use a direct coating method in which a polishing layer is directly formed on a base material without using double-sided tape or an adhesive.

<Physical characteristics of polyurethane resin sheet>
(Thickness)
The thickness of the polyurethane resin sheet in the polishing pad of the present invention is not particularly limited, but is preferably about 0.3 to 2 mm.

(Density D)
The density of the polyurethane resin sheet in the polishing pad of the present invention is preferably 0.15~0.50g / cm ^3, more preferably 0.18~0.35g / cm ^3. When the density is within the above range, the polishing characteristics (polishing rate, shape) can be easily controlled.

(Compression rate)
In the present specification, the compression ratio is an index of the softness of the polishing pad.
The compression ratio can be determined by using a shopper type thickness measuring instrument (pressurized surface: circular with a diameter of 1 cm) in accordance with Japanese Industrial Standards (JIS L 1021). Specifically, it is as follows.
The thickness t0 after applying the initial load for 30 seconds from the unloaded state is measured, and then the thickness t1 after applying the final pressure for 30 seconds from the state of the thickness t0 is measured. The compression rate can be calculated by the formula of compression rate (%) = 100 × (t0-t1) / t0 (note that the initial load is 100 g / cm ² and the final pressure is 1120 g / cm ² ).
The polyurethane resin sheet in the polishing pad of the present invention preferably has a compression ratio of 1 to 70%, more preferably 3 to 60%, still more preferably 4 to 40%, and 5 to 20%. % Is particularly preferable. When the compression ratio is within the above range, the scratch performance and the polishing rate are well balanced.

(Compressive modulus)
In the present specification, the compressive elastic modulus is an index of the ease of return to the compressive deformation of the polishing pad or the polyurethane resin sheet.
The compressive elastic modulus can be determined by using a shopper type thickness measuring instrument (pressurized surface: circular with a diameter of 1 cm) in accordance with Japanese Industrial Standards (JIS L 1021). Specifically, it is as follows.
_{The thickness t 0} after applying the initial load for 30 seconds from the unloaded state is measured, and then the thickness _{t 1} after applying the final load for 5 minutes from the state of the _{thickness t 0} is measured. Next, _{all the loads are removed from the state of the thickness t 1} , and after leaving for 5 minutes (the state of no load), the initial load is applied again for 30 seconds, and then the thickness t _0'is measured. Compressive modulus, compression modulus (%) = 100 × (t 0 '-t 1) / (t 0 -t 1) can be calculated by the formula (Incidentally, the initial load 100 g / cm ^2, the final The load is 1120 g / cm ² ).
The polyurethane resin sheet in the polishing pad of the present invention preferably has a compressive elastic modulus (%) of 50 to 100%, more preferably 70 to 100%, and even more preferably 80 to 100%. preferable. When the compressive elastic modulus is within the above range, the deformation of the pad due to the polishing load can be reduced, and the polishing characteristics can be maintained in a stable state.

(Shore A hardness)
In the present specification, the shore A hardness means a value measured according to JIS K7311.
The shore A hardness of the polyurethane resin sheet in the polishing pad of the present invention is preferably 1 to 40 degrees, more preferably 5 to 38 degrees, still more preferably 10 to 35 degrees, and 15 to 15 degrees. It is particularly more preferably 30 degrees. When the shore A hardness is within the above range, the scratch performance and the polishing rate are well balanced.

(Average opening diameter)
In the present specification, the average pore diameter is an average value of the circle-equivalent diameter calculated from the area and number of the pored portions obtained by binarizing the surface image of the polishing pad or the polyurethane resin sheet.
The average opening diameter of the polyurethane resin sheet in the polishing pad of the present invention is preferably in the range of 20 to 80 μm, more preferably 25 to 70 μm, and even more preferably 30 to 60 μm.
When the average pore size is within the above range, the retention of the slurry is good and a stable polishing rate can be obtained.

(Aperture ratio)
In the present specification, the opening ratio means the ratio (%) of the opening area to the surface (polished surface) of the polishing pad or the polyurethane resin sheet.
The aperture ratio of the polyurethane resin sheet in the polishing pad of the present invention is preferably in the range of 5 to 50%, more preferably 7 to 35%, and even more preferably 10 to 30%.
When the aperture ratio is within the above range, the retention of the slurry is good and a stable polishing rate can be obtained.

<Physical characteristics of polishing pad>
(Thickness)
The thickness of the polishing pad of the present invention is not particularly limited, but is preferably about 0.5 to 3 mm.

(density)
The density of the polishing pad of the present invention is preferably 0.15~0.4g / cm ^3, more preferably 0.21~0.31g / cm ^3. When the density is within the above range, the polishing rate and the scratch performance are well balanced.

(Compression rate)
The polishing pad of the present invention preferably has a compression ratio of 10 to 70%, more preferably 15 to 55%, and even more preferably 20 to 50%, as measured under the above conditions. It is particularly preferably 25 to 45%. When the compression ratio is within the above range, the polishing rate and the scratch performance are well balanced.

(Compressive modulus)
The polishing pad of the present invention preferably has a compressive elastic modulus (%) of 50 to 100%, more preferably 70 to 100%, and even more preferably 85 to 100%. When the compressive elastic modulus is within the above range, the deformation of the pad due to the polishing load can be reduced, and the polishing characteristics can be maintained in a stable state.

(Shore A hardness)
The shore A hardness of the polishing pad of the present invention is preferably 5 to 40 degrees, more preferably 10 to 35 degrees, and even more preferably 15 to 30 degrees. When the shore A hardness is within the above range, the polishing rate and the scratch performance are well balanced.

(Use)
The polishing pad of the present invention can be suitably used for polishing silicon, a hard disk, a mother glass for a liquid crystal display, a semiconductor device, and a cover glass, particularly for chemical mechanical polishing (CMP) of a semiconductor device.

When the polishing pad of the present invention is used, it is attached to the polishing surface plate of the polishing machine so that the polishing surface of the polyurethane resin sheet constituting the polishing pad faces the object to be polished. Then, while supplying the slurry, the polishing surface plate is rotated to polish the processed surface of the object to be polished.
Examples of the object to be polished processed by the polishing pad of the present invention include a glass substrate for a hard disk, an aluminum substrate, a mother glass for an LCD, a semiconductor wafer, a semiconductor device, and a cover glass. Above all, the polishing pad of the present invention is suitably used for processing a semiconductor device.
The type of slurry used for polishing the object to be polished using the polishing pad of the present invention is not particularly limited, and for example, a slurry containing a surfactant and / or abrasive grains can be used. Examples of the surfactant contained in the slurry include the same surfactants as the foaming aid. In the polishing pad of the present invention, since the amount of calcium salt and calcium and magnesium derived from the magnesium salt contained in the polyurethane resin sheet is reduced, a surfactant (for example, an anionic surfactant) is contained in the slurry. Even so, it is difficult for organic residue (soap residue) to be formed during polishing of the object to be polished, and the amount of the organic residue adhering to the object to be polished can be reduced. Therefore, the slurry can be freely selected and used according to the intended use without being restricted by the type of additive in the slurry.
The polishing pad of the present invention can preferably be produced by the following method.

<< Manufacturing method of polishing pad >>
The method for producing a polishing pad of the present invention includes a step of preparing a polyurethane resin-containing solution containing a polyurethane resin and a solvent, and a step of immersing the polyurethane resin-containing solution in a coagulating solution to coagulate the polyurethane resin, and the coagulation The hardness component concentration, which is a value obtained by converting the concentrations of calcium and magnesium derived from the calcium salt and magnesium salt contained in the solution into the concentration of calcium carbonate in the same molar amount, is 60.0 mg / L or less.

<Hardness component concentration>
In the present specification and the scope of the patent claim, the hardness component concentration is the concentration of calcium and magnesium derived from the calcium salt and magnesium salt contained in the solution, and the concentration of calcium carbonate in the same molar amount as the total of the calcium and magnesium. The converted value is calculated by the formula (2) below.
Hardness component concentration (mg / L) = Ca concentration (mg / L) x 2.496 + Mg concentration (mg / L) x 4.119 ... (2)
The numerical value "2.496" in the above formula is a value calculated by the molecular weight of calcium carbonate / the molecular weight of calcium, and the numerical value "4.119" is calculated by the molecular weight of calcium carbonate / the molecular weight of magnesium. The value.
In the above, the hardness component concentration is specified in mg / L, but when the mass of the solution is clear, the hardness component concentration may be specified in terms of the mass per 1 kg of the solution, that is, mg / kg.
Calcium salt-derived calcium and magnesium salt-derived magnesium contained in the coagulation liquid may be present in the coagulation liquid as calcium ions and magnesium ions, respectively, or may be present in the coagulation liquid as salts with anions. Good.
Hereinafter, each step of the production method of the present invention will be described.

<Preparation process of resin solution>
In this preparation step, a polyurethane resin is added to and mixed with a solvent (hereinafter, may be referred to as solvent 1) to prepare a polyurethane resin-containing solution containing the polyurethane resin and the solvent.
(Polyurethane resin)
As the raw material polyurethane resin, for example, the polyurethane resin described in the above section << Polishing pad >> can be used. The polyurethane resin preferably has a resin modulus of 1 to 20 MPa, preferably 3 to 15 MPa, and most preferably 4 to 12 MPa.

(solvent)
Examples of the solvent for dissolving the resin include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), acetone, acetonitrile, and N-methylpyrrolidone (DMSO). NMP) and the like and mixtures thereof. Among these, DMF is preferable. Foaming is formed by substituting the polar organic solvent in the urethane resin solution with water in the coagulation solution during solidification.

The polyurethane resin is preferably contained in the polyurethane resin-containing solution at a ratio of 100 to 800 parts by mass of the solvent with respect to 100 parts by mass of the polyurethane resin, and 150 to 600 parts by mass of the solvent with respect to 100 parts by mass of the polyurethane resin. The ratio of the solvent is more preferably 200 to 500 parts by mass with respect to 100 parts by mass of the polyurethane resin. The polyurethane resin and solvent usually contain almost no calcium salt and magnesium salt, but when the polyurethane resin and solvent contain a large amount of calcium and / or magnesium derived from calcium salt and magnesium salt, polyurethane is used. It is preferable to adjust the hardness component concentration, the calcium concentration, and the magnesium concentration in the resin-containing solution so as to be equal to or less than the respective concentrations contained in the following coagulation liquid.

The polyurethane resin-containing solution may contain a filler, an additive, or the like in addition to the above components. The filler and the additive may be added to the solvent before the polyurethane resin is dissolved in the solvent, or may be added to the solution obtained by dissolving the polyurethane resin in the solvent.

<Filler>
As the filler, for example, the filler described in the above section << Polishing pad >> can be used.
When a filler is used, the filler is preferably contained in the polyurethane resin-containing solution at a ratio of 0.1 to 30 parts by mass with respect to 100 parts by mass of the polyurethane resin, and more preferably 1 to 20 parts by mass. It is even more preferably contained in an amount of 1 to 15 parts by mass, and even more preferably contained in an amount of 2 to 10 parts by mass. When the ratio of the filler is within the above range, the polishing rate of the obtained polishing pad can be improved. In addition, the dressing property of the surface can be improved by imparting brittleness.

The filler may be mixed with a component such as a polyurethane resin or a solvent 1 in the form of a dispersion liquid dispersed in a solvent (hereinafter, may be referred to as a solvent 2). The solvent 2 may be the same solvent as the solvent 1 or a different solvent, and is preferably the same solvent. When the filler is mixed with the polyurethane resin and the solvent 1 in the form of a dispersion liquid in which the filler is dispersed in the solvent 2, the amount of the filler-derived hardness component contained in the polyurethane resin-containing solution is 20 per 1 kg of the solid content of the polyurethane resin-containing solution. It is preferably 0.0 mg or less, more preferably 15.0 mg or less, and even more preferably 10.0 mg or less. When the amount of the hardness component is within the above range, it is effective in reducing the amount of organic residue adhering to the object to be polished.
The lower limit of the amount of the hardness component derived from the filler contained in the polyurethane resin-containing solution is not particularly limited, and may be, for example, 0 mg or more per 1 kg of solid content of the polyurethane resin-containing solution, or 0.1 mg or more. It may be 0.5 mg or more, or 1.0 mg or more.

The total concentration of calcium salt derived from the filler and calcium and magnesium derived from the magnesium salt contained in the polyurethane resin-containing solution shall be 2.0 × 10 ^-4 mol or less per 1 kg of solid content of the polyurethane resin-containing solution. Is more preferable, and it is more preferably 1.5 × 10 ^-4 mol or less, and even more preferably 1.0 × 10 ^-4 mol or less. The lower limit of the total concentration of the calcium salt derived from the filler and the calcium and magnesium derived from the magnesium salt contained in the polyurethane resin-containing solution is not particularly limited, and is, for example, 0 mol or more per 1 kg of the solid content of the polyurethane resin-containing solution. It may be 0.1 × 10 ^-5 mol or more, 0.5 × 10 ^-5 mol or more, or 1.0 × 10 ^-5 mol or more.
The calcium salt-derived calcium and the magnesium salt-derived magnesium contained in the polyurethane resin-containing solution may be present in the polyurethane resin-containing solution as calcium ions and magnesium ions, respectively, and the polyurethane resin-containing solution as a salt with an anion. It may be present in.

When the filler is mixed with the polyurethane resin and the solvent 1 in the form of a dispersion liquid, the value obtained by converting the amount of calcium derived from the calcium salt contained in the filler into the amount of calcium carbonate in the same mole is 150 mg or less per 1 kg of the filler. It is preferably 120 mg or less, and even more preferably 60 mg or less. When the value obtained by converting the amount of calcium into the amount of calcium carbonate in the same mole is within the above range, it is effective in reducing the amount of organic residue adhering to the object to be polished.
The lower limit of the value obtained by converting the amount of calcium derived from the calcium salt contained in the filler into the concentration of calcium carbonate in the same mole is not particularly limited, and may be, for example, 0 mg or more per 1 kg of the dispersion liquid, 0.1 mg. It may be more than or equal to 0.5 mg or more, and may be 1.0 mg or more.

The amount of calcium derived from the calcium salt contained in the filler ^{is preferably 1.5 × 10 -3} mol or less, ^{more preferably 1.2 × 10 -3} mol or less, per 1 kg of the filler. It is even more preferably 0.6 × 10 ^{-3 mol or less.} The lower limit of the amount of calcium derived from the calcium salt contained in the filler is not particularly limited, and may be, for example, 0 mol or more, 0.1 × 10 ^-5 mol or more, or 0, per 1 kg of the filler. It may be .5 × 10 ^-5 mol or more, or 1.0 × 10 ^-5 mol or more.

When the filler is mixed with the polyurethane resin and the solvent 1 in the form of a dispersion liquid, the value obtained by converting the amount of magnesium derived from the magnesium salt contained in the filler into the amount of calcium carbonate in the same mole is 80 mg or less per 1 kg of the filler. It is preferably 50 mg or less, and even more preferably 30 mg or less. When the value obtained by converting the amount of magnesium into the amount of calcium carbonate in the same mole is within the above range, it is effective in reducing the amount of organic residue adhering to the object to be polished.
There is no particular limitation on the lower limit of the value obtained by converting the amount of magnesium derived from the magnesium salt contained in the filler into the amount of calcium carbonate in the same mole, and for example, it may be 0 mg or more per 1 kg of the filler, and 0.1 mg or more. It may be 0.5 mg or more, or 1.0 mg or more.

The amount of magnesium derived from the magnesium salt contained in the filler ^{is preferably 0.8 × 10 -3} mol or less, ^{more preferably 0.5 × 10 -3} mol or less, and 0. Even more preferably, it is 3 × 10 ^{-3 mol or less.} The lower limit of the amount of magnesium derived from the magnesium salt contained in the filler is not particularly limited, and may be, for example, 0 mol or more, 0.1 × 10 ^-5 mol or more, or 0, per 1 kg of the filler. It may be 0.5 × 10 ^-5 mol or more, or 1.0 × 10 ^-5 mol or more.

(Additive)
Examples of the additive include a foaming aid and a film-forming stabilizer. Examples of the foaming aid include anionic surfactants, nonionic surfactants, and amphoteric surfactants. Among these, anionic surfactants are preferable, fatty acid-based anionic surfactants are more preferable, and sodium salts and potassium salts of higher fatty acids are preferable in order to form large foaming, for example, sodium lauryl sulfate and the like. , Sodium salts of monolong chain (preferably C8-C18, more preferably C10-C14) alkyl esters of sulfuric acid.
The anionic surfactant is preferably contained in the polyurethane resin solution at a ratio of 0 to 15 parts by mass, preferably 0.1 to 15 parts by mass, and 1 to 12 parts by mass with respect to 100 parts by mass of the polyurethane resin. More preferred. When the content of the anionic surfactant is within the above range, foaming can be increased during wet solidification. Further, the film forming property can be improved. Further, in the conventional polishing pad, if an anionic surfactant is used during the manufacturing process, soap residue may be generated by combining with calcium derived from calcium salt and magnesium derived from magnesium salt contained in the coagulating liquid described later. In the production method of the present invention, calcium derived from calcium salt and magnesium derived from magnesium salt in the coagulating liquid are significantly reduced, so that the amount of soap residue generated can be suppressed even when an anionic surfactant is used. , The amount of organic residue adhering to the object to be polished can be reduced.
Foaming aids and film-forming stabilizers usually contain almost no components that give calcium and magnesium derived from calcium salts and magnesium salts, but the foaming aids and film-forming stabilizers are derived from calcium salts and magnesium salts. When a large amount of calcium and / or magnesium is contained, the hardness component concentration, calcium concentration, and calcium concentration in the polyurethane resin-containing solution containing the foaming aid and / or the film-forming stabilizer are determined in the coagulating solution below. It is preferable to adjust the concentration to be less than or equal to each concentration contained in.

<Applying process>
The polyurethane resin-containing solution obtained in the preparation step is applied onto the film-forming substrate. The coating method is not particularly limited, and for example, the polyurethane resin-containing solution may be continuously coated on the film-forming substrate by a knife coater, a reverse coater, or the like so as to be substantially uniform. As the film-forming base material, any base material usually used in the present technical field can be used without particular limitation. Examples include a flexible polymer film such as a polyester film and a polyolefin film, and a non-woven fabric impregnated and fixed with an elastic resin. Among them, a polyester film is preferably used.

<Coagulation process>
Next, the polyurethane resin in the polyurethane resin-containing solution is solidified by a wet film forming method.
The wet film-forming method is a method of coagulating and regenerating a polyurethane resin by immersing a base material coated with a polyurethane resin-containing solution in a coagulating solution containing water, which is a poor solvent for the polyurethane resin, as a main component. is there. In the coagulation liquid, the solvent (for example, DMF) of the polyurethane resin-containing solution and the coagulation liquid are replaced, and the polyurethane resin is coagulated and regenerated. In wet coagulation, when immersed in a coagulating liquid, a surface film called a skin layer is formed at the interface, and the resin solidifies by replacing the solvent and the coagulating liquid in the resin solution through the film. Since coagulation proceeds inward from the skin layer, teardrop-like foaming peculiar to wet coagulation that increases from the skin layer side to the inside is formed in the thickness direction.
As the coagulating liquid, water, a mixed solution of water and a polar solvent such as DMF, or the like is used. Examples of the polar solvent include water-miscible organic solvents such as DMF, DMAc, THF, DMSO, NMP, acetone, IPA (isopropyl alcohol), ethanol and methanol. The concentration of the polar solvent in the coagulation liquid is preferably 0 to 20% by mass.
The temperature and immersion time of the coagulation liquid are not particularly limited, and may be immersed at, for example, 15 to 50 ° C. for 10 to 100 minutes.

The hardness component concentration, which is the value obtained by converting the concentration of calcium and magnesium derived from the calcium salt and magnesium salt contained in the coagulation liquid into the concentration of calcium carbonate in the same molar amount, is 60 mg or less per 1 L of the coagulation liquid, and is 45 mg or less. It is preferably present, and more preferably 30 mg or less. When the hardness component concentration is within the above range, the contents of the calcium component and the magnesium component in the polyurethane resin sheet to be solidified and regenerated can be reduced, and the amount of organic residue adhering to the object to be polished can be reduced.
The lower limit of the hardness component concentration is not particularly limited, and for example, it may be 0 mg or more, 0.1 mg or more, 0.5 mg or more, or 1.0 mg or more per 1 L of the coagulating liquid. It may be.

The total concentration of calcium salt and calcium and magnesium derived from the magnesium salt contained in the coagulation liquid ^{is preferably 6.0 × 10 -4} mol or less per 1 L of the coagulation bath, preferably 4.5 × 10 ^-4 mol. It is more preferably 3.0 × 10 ^-4 mol or less, and even more preferably 3.0 × 10 -4 mol or less. The lower limit of the total concentration of calcium salt and calcium and magnesium derived from the calcium salt and magnesium salt contained in the coagulating liquid is not particularly limited, and may be, for example, 0 mol or more per 1 L of the coagulated liquid, and 0.1 × 10 ^-5 mol. It may be 0.5 × 10 ^-5 mol or more, or 1.0 × 10 ^-5 mol or more.

The value obtained by converting the concentration of calcium derived from the calcium salt contained in the coagulation liquid into the concentration of calcium carbonate in the same mole is preferably 44.0 mg or less per 1 L of the coagulation liquid, and preferably 40.0 mg or less. More preferably, it is 20.0 mg or less, and even more preferably. When the value obtained by converting the concentration of calcium derived from the calcium salt into the concentration of calcium carbonate in the same mole is within the above range, it is effective in reducing the amount of organic residue adhering to the object to be polished.
There is no particular limitation on the lower limit of the value obtained by converting the calcium concentration derived from the calcium salt into the concentration of calcium carbonate in the same mole, and for example, it may be 0 mg or more or 0.1 mg or more per 1 L of the coagulation liquid. , 0.5 mg or more, or 1.0 mg or more.

Further, the concentration of calcium derived from the calcium salt contained in the coagulation liquid ^{is preferably 4.4 × 10 -4} mol or less per 1 L of the coagulation bath, and more preferably 4.0 × 10 ^-4 mol or less. It is preferably 2.0 × 10 ^-4 mol or less, and even more preferably 2.0 × 10 -4 mol or less. The lower limit of the concentration of calcium derived from the calcium salt contained in the coagulation liquid is not particularly limited, and may be, for example, 0 mol or more, or 0.1 × 10 ^-5 mol or more per 1 L of the coagulation liquid. , 0.5 × 10 ^-5 mol or more, or 1.0 × 10 ^-5 mol or more.

The value obtained by converting the concentration of magnesium derived from the magnesium salt contained in the coagulating liquid into the concentration of calcium carbonate in the same mole is preferably less than 19.5 mg per 1 L of the coagulated liquid, and more preferably 19.0 mg or less. It is preferably 10.0 mg or less, and even more preferably 10.0 mg or less. When the value obtained by converting the concentration of magnesium derived from the magnesium salt into the concentration of calcium carbonate in the same mole is within the above range, it is effective in reducing the amount of organic residue adhering to the object to be polished.
There is no particular limitation on the lower limit of the value obtained by converting the magnesium concentration derived from the magnesium salt into the concentration of calcium carbonate in the same mole, and for example, it may be 0 mg or more or 0.1 mg or more per 1 L of the coagulation liquid. , 0.5 mg or more, or 1.0 mg or more.

Further, the concentration of magnesium derived from the magnesium salt contained in the coagulation liquid ^{is preferably less than 2.0 × 10 -4} mol per 1 L of the coagulation liquid, and more preferably 1.9 × 10 ^-4 mol or less. It is preferably 1.0 × 10 ^-4 mol or less, and even more preferably 1.0 × 10 -4 mol or less. The lower limit of the concentration of magnesium derived from the magnesium salt contained in the coagulation liquid is not particularly limited, and may be, for example, 0 mol or more, or 0.1 × 10 ^-5 mol or more per 1 L of the coagulation liquid. , 0.5 × 10 ^-5 mol or more, or 1.0 × 10 ^-5 mol or more.
As a method for keeping the hardness component concentration, calcium concentration and / or magnesium concentration of the coagulation liquid within the above range, for example, a method of treating the coagulation liquid using an ultrafiltration membrane or a reverse osmosis membrane after preparing the coagulation liquid. Can be mentioned. The pore diameters of the ultrafiltration membrane and the reverse osmosis membrane are preferably 0.0001 to 0.1 μm, more preferably 0.0005 to 0.05 μm, even more preferably 0.001 to 0.02 μm, and 0.001 to 0.001. 0.005 μm is particularly preferable. Ion-exchanged water (soft water) or the like can also be applied as long as the hardness component concentration of the coagulating liquid is within the above range.

When the hardness component concentration of the coagulation liquid is high, the polyurethane resin sheet contains a large amount of calcium and magnesium due to replacement by wet coagulation. In the process of preparing the polyurethane resin-containing solution, an anionic surfactant such as a sodium salt of a higher fatty acid may be added as a foaming aid for the formation and adjustment of foaming, but most of them coagulate in the coagulation step. Although it elutes in the liquid, part of it remains on the polyurethane resin sheet. At this time, if the coagulation liquid contains a large amount of calcium and magnesium derived from calcium salt and magnesium salt, sodium derived from the sodium salt of the anionic surfactant is contained in the coagulation liquid at the time of elution. It is considered that by substituting with the derived calcium and magnesium, soap residue that is insoluble in water and has viscosity is formed and easily remains in the polyurethane resin sheet. This soap scum is insoluble in water and adheres to the object to be polished as an organic residue during the polishing process. As a result, convex defects increase. The present invention can reduce the formation of soap scum by reducing the concentration of the hardness component of the coagulating liquid, and can improve the problem that the organic residue adheres to the object to be polished and causes convex defects.

<Washing and drying process>
The sheet-shaped polyurethane resin obtained by coagulating with a coagulating liquid is washed and dried.
The cleaning treatment removes the solvent remaining in the polyurethane resin-containing solution. Examples of the cleaning liquid used for cleaning include water. For the purpose of further reducing the amount of calcium salt and calcium and magnesium derived from the calcium salt and magnesium salt contained in the polyurethane resin sheet, cleaning with dilute acid, chelate cleaning, neutralization cleaning, cleaning with pure water and the like may be added. .. If the cleaning solution contains a large amount of calcium and magnesium derived from calcium salts and magnesium salts, adjust the hardness component concentration, calcium concentration, and magnesium concentration of the cleaning solution so that they are equal to or less than the respective concentrations contained in the coagulating solution. Is preferable.
After cleaning, the polyurethane resin is dried. The drying treatment may be carried out by a conventional method, for example, drying at 100 to 180 ° C. for about 5 to 30 minutes in a dryer. A polyurethane resin sheet can be obtained through the above steps. In addition, the cleaning liquid and the like are squeezed as much as possible before drying, and the water of the coagulating liquid containing calcium and magnesium derived from calcium salt and magnesium salt and the water of the cleaning liquid are reduced as much as possible and then dried to be contained in the sheet-shaped polyurethane resin. The amount of hardness component can be reduced.

<Buffing process>
The polyurethane resin sheet obtained after the washing and drying step may be buffed. When buffing, the polished surface of the polyurethane resin sheet may be buffed, or the surface opposite to the polished surface may be buffed. When the polished surface of the polyurethane resin sheet is buffed, it is preferable to remove a part or all of the skin layer of the polyurethane resin sheet, and it is more preferable to remove all of the skin layer.

<Multilayer formation process>
The manufacturing method of the present invention may include a step of bonding the polyurethane resin sheet to another layer (lower layer, support layer) on the surface opposite to the polished surface of the polyurethane resin sheet. Examples of the other layer include the other layers described in the above section << Polishing pad >>. As a method of bonding to another layer, for example, the polyurethane resin sheet and the other layer may be bonded and fixed while being pressed as necessary using double-sided tape or an adhesive. The double-sided tape and adhesive used at this time are not particularly limited, and can be arbitrarily selected from the double-sided tapes and adhesives known in the art.

Further, in the polishing pad of the present invention, the front surface and / or the back surface of the polishing layer may be ground, and the surface may be grooved or embossed, if necessary, and the base material and / or the adhesive layer may be subjected to. May be bonded to the polishing layer, or may be provided with a light transmitting portion.
The method of grinding is not particularly limited, and grinding can be performed by a known method. Specifically, grinding with sandpaper can be mentioned. This makes it possible to obtain a suede-like polished surface.
The shape of grooving and embossing is not particularly limited, and examples thereof include a lattice type, a concentric type, and a radial type.

<< Manufacturing of polishing pads >>
Polishing pads of Examples 1 to 6 and Comparative Examples 1 and 2 were manufactured using the following materials and manufacturing methods. Tables 1 and 2 show the compositions of the polyurethane resin-containing solutions used in producing the polishing pads of each Example and Comparative Example. Tables 3 to 4 show the calcium salt and the calcium concentration derived from the magnesium salt and the magnesium concentration contained in the coagulation liquid used in the coagulation step.

<Example 1>
(1) Preparation Step of Resin Solution A 30 mass% polyurethane resin-containing solution in which a polyester-based polyurethane resin (100% modulus: 6 MPa) was dissolved in N, N-dimethylformamide (DMF) was prepared.
(2) Coating Step The polyurethane resin-containing solution was substantially uniformly coated on the strip-shaped film-forming substrate (polyethylene terephthalate) at room temperature by a coating device such as a knife coater.
(3) Coagulation liquid (hardness component concentration) obtained by treating the polyurethane resin-containing solution applied on the film-forming substrate obtained in the coagulation step (2) with an ultrafiltration membrane (pore size: 0.01 μm). Was wet-coagulated at 18 ° C. for 75 minutes using 58.6 mg / L of water). As a result, a polyurethane resin sheet was formed on the film-forming substrate.
(4) Washing and Drying Step The polyurethane resin sheet was peeled off from the film-forming substrate and washed with water having a hardness component concentration of 58.6 mg / L to remove DMF remaining in the polyurethane resin sheet. Then, the polyurethane resin sheet was dried at 135 ° C. for 10 minutes using a dryer.
(5) Buffing Step After drying, the skin layer side formed on the surface of the obtained polyurethane resin sheet was buffed.
(6) Bonding Step The base material (polyethylene terephthalate resin sheet having a thickness of 188 μm) and the surface of the buffed polyurethane resin sheet opposite to the buffed surface were bonded using an adhesive.
(7) Lamination process A double-sided tape was attached to the surface opposite to the surface to which the polyurethane resin sheet of the base material was attached.
(8) Embossing process A wire mesh having a grid-like embossing pattern and a polyurethane resin sheet to which a base material and double-sided tape are bonded are sandwiched between upper and lower heat platens and then heat-pressed to buff the polyurethane resin sheet. The surface was embossed with irregularities corresponding to the wire mesh lattice to obtain the polishing pad of Example 1.

<Example 2>
(1) Resin solution preparation step N, N-dimethylformamide (DMF), 30% by mass polyester polyurethane resin (100% modulus: 6MPa) solution, and 20% by mass silica (manufactured by Gokoku Dye Co., Ltd., product name GO #) 2167 (primary particle size (average): 169 nm, dispersion diameter: 256 nm)) DMF dispersion is mixed so that 30 mass% polyurethane resin solution: DMF: 20 mass% silica DMF dispersion = 100: 41: 12. A polyurethane resin-containing solution was prepared.
(2) Coating Step The polyurethane resin-containing solution was substantially uniformly coated on the strip-shaped film-forming substrate (polyethylene terephthalate) at room temperature by a coating device such as a knife coater.
(3) Coagulation liquid (hardness component concentration) obtained by treating the polyurethane resin-containing solution applied on the film-forming substrate obtained in the coagulation step (2) with an ultrafiltration membrane (pore size: 0.01 μm). Was wet-coagulated at 18 ° C. for 75 minutes using 58.6 mg / L of water). As a result, a polyurethane resin sheet was formed on the film-forming substrate.
(4) Washing and Drying Step The polyurethane resin sheet was peeled off from the film-forming substrate and washed with water having a hardness component concentration of 58.6 mg / L to remove DMF remaining in the polyurethane resin sheet. Then, the polyurethane resin sheet was dried at 135 ° C. for 10 minutes using a dryer.
(5) Buffing Step After drying, the skin layer side formed on the surface of the obtained polyurethane resin sheet was buffed.
(6) Bonding Step The base material (polyethylene terephthalate resin sheet having a thickness of 188 μm) and the surface of the buffed polyurethane resin sheet opposite to the buffed surface were bonded using an adhesive.
(7) Lamination process A double-sided tape was attached to the surface opposite to the surface to which the polyurethane resin sheet of the base material was attached.
(8) Embossing process A wire mesh having a grid-like embossing pattern and a polyurethane resin sheet to which a base material and double-sided tape are bonded are sandwiched between upper and lower heat platens and then heat-pressed to buff the polyurethane resin sheet. The surface was embossed with irregularities corresponding to the wire mesh lattice to obtain the polishing pad of Example 2.

<Example 3>
In step (1), 30% by mass polyester-based polyurethane was added to N, N-dimethylformamide (DMF) so that 30% by mass polyurethane resin solution: DMF: 20% by mass silica DMF dispersion = 100: 41: 27. The polishing pad of Example 3 was obtained by the same method as in Example 2 except that the resin (100% modulus: 6 MPa) solution and the 20 mass% silica DMF dispersion were mixed.

<Example 4>
In step (1), a polyurethane resin having a 100% modulus of 12 MPa was used in the 30 mass% polyester polyurethane resin solution, and 1 part by mass of sodium lauryl sulfate (sunlight) was used as an additive with respect to 100 parts by mass of the 30 mass% polyurethane resin solution. Example 4 by the same method as in Example 2 except that 3.3 parts by mass of sodium lauryl sulfate was mixed with 100 parts by mass of polyurethane resin (manufactured by Chemicals, Inc., product name NIKKOL SLS). Obtained a polishing pad.

<Example 5>
In step (1), a polyurethane resin having a 100% modulus of 8 MPa was used in a 30 mass% polyester polyurethane resin solution, and 15 mass% carbon black (manufactured by DIC, product name: Dyrac) was used instead of the 20 mass% silica DMF dispersion. 16 parts by mass of black (primary particle size (average): 30 nm, dispersion diameter: 428 nm) DMF dispersion is used with respect to 100 parts by mass of 30 mass% polyurethane resin solution, and 100 mass by mass of 30 mass% polyurethane resin solution is used as an additive. Except that 1 part by mass of sodium lauryl sulfate (manufactured by Nikko Chemicals, product name NIKKOL SLS) was mixed (3.3 parts by mass of sodium lauryl sulfate was mixed with 100 parts by mass of polyurethane resin). The polishing pad of Example 5 was obtained by the same method as in Example 2.

<Example 6>
In step (1), a polyurethane resin having a resin modulus of 10 MPa was used in a 30 mass% polyester polyurethane resin solution, and 15 mass% carbon black (manufactured by DIC, product name: Dailac Black) was used instead of the 20 mass% silica DMF dispersion. (Primary particle size (average): 22 nm, dispersion diameter: 375 nm)) 16 parts by mass of the DMF dispersion was used with respect to 100 parts by mass of the 30 mass% polyurethane resin solution, and 100 parts by mass of the 30 mass% polyurethane resin solution was used as an additive. 3 parts by mass of sodium lauryl sulfate (manufactured by Nikko Chemicals, product name NIKKOL SLS) was mixed (10.0 parts by mass of sodium lauryl sulfate was mixed with 100 parts by mass of polyurethane resin), and step (3) In the above, instead of the coagulating solution treated with the ultrafiltration membrane, the coagulating solution (water having a hardness component concentration of 15.1 mg / L) obtained by treating with a back-penetrating film (pore size: 0.002 μm) was used. The polishing pad of Example 6 was obtained by the same method as in Example 2 except for the above.

<Comparative example 1>
In step (3), instead of the coagulation liquid treated with the ultrafiltration membrane, the coagulation liquid obtained by treatment with a microfiltration membrane (pore diameter: 0.05 μm) (water having a hardness component concentration of 64.7 mg / L). The polishing pad of Comparative Example 1 was obtained by the same method as in Example 6 except that the above was used.

<Comparative example 2>
In the step (1), instead of the 20% by mass silica DMF dispersion, the DMF of 15% by mass carbon black (manufactured by DIC, product name: Dilac Black (primary particle size (average): 22 nm, dispersion size: 375 nm)). 35 parts by mass of the dispersion is used with respect to 100 parts by mass of the 30 mass% polyurethane resin solution, and 5 parts by mass of sodium lauryl sulfate (manufactured by Nikko Chemicals Co., Ltd.) is used as an additive with respect to 100 parts by mass of the 30 mass% polyurethane resin solution. Polishing of Comparative Example 2 by the same method as in Example 2 except that it was mixed using the name NIKKOL SLS) (mixed with 16.7 parts by mass of sodium lauryl sulfate with respect to 100 parts by mass of polyurethane resin). Got a pad.

<< Physical characteristics >>
For the polishing pads of Examples 1 to 6 and Comparative Examples 1 and 2, the physical characteristics (thickness, density, compression modulus, compressive modulus, shore A hardness, average pore diameter, pore ratio) of the polyurethane resin sheet were obtained by the following methods. , Calcium salt and magnesium salt-derived calcium amount and magnesium amount), and physical characteristics (thickness, density, compression modulus, compressive modulus, shore A hardness) of the polishing pad were measured. The results are shown in Tables 5-8.

(Density g / cm ³ )
The density is determined by cutting out a sample piece (10 cm x 10 cm) from a polishing pad or polyurethane resin sheet, measuring the mass of the sample piece with an automatic balance, and then using the following formula:
Density (g / cm ³ ) = Mass (g) / (10 cm x 10 cm x sample piece thickness cm)
Measured by.

(Compression rate%, compressive elastic modulus%)
The compressibility and compressibility were measured using a shopper type thickness measuring device (pressurized surface: circular with a diameter of 1 cm) in accordance with JIS L1021. Specifically, the thickness t0 after applying the initial load for 30 seconds from the unloaded state was measured, and then the thickness t1 after applying the final pressure for 30 seconds from the state of the thickness t0 was measured. After removing all the loads from the state of the thickness t1 and leaving it for 5 minutes (in the no-load state), the initial load was applied again for 30 seconds, and then the thickness t0'was measured.
Compression rate (%) = 100 × (t0-t1) / t0
Compressive modulus (%) = 100 × (t0'-t1) / (t0-t1)
The initial load is 100 g / cm ² and the final pressure is 1120 g / cm ² .

(Shore A hardness)
For Shore A hardness, a sample piece (10 cm x 10 cm) is cut out from a polishing pad or a polyurethane resin sheet, and a plurality of the sample pieces are stacked so as to have a thickness of 4.5 mm or more, and an A type hardness tester (Japanese Industrial Standards) is used. , JISK7311).

(Average hole diameter, aperture ratio)
For the average pore size and aperture ratio, the polished surface of the polyurethane resin sheet was magnified 100 times with a scanning electron microscope (JMS-5500LV, manufactured by JEOL Ltd.) and observed at 9 locations, and then these images were imaged. It was calculated by binarizing with processing software (Image Analyzer V20LAB Ver.1.3 manufactured by Nikon Ltd.).

(Calcium amount and magnesium amount)
About 0.1 g of the sample was precisely weighed in a conical beaker, and 10 ml of nitric acid + 3 ml of sulfuric acid was added to the sample. It was covered with a watch glass and warmed to decompose organic components and heated until the solution was small. After allowing to cool, 3 ml of hydrogen peroxide was added and the mixture was reheated until the amount of the liquid became small. While filtering with a filter paper, the sample was prepared by measuring up to 50 ml with 1N nitric acid.
Then, using this sample, the content of calcium and magnesium derived from calcium salt and magnesium salt was measured by an analyzer.
Analytical method: ICP emission spectroscopic analysis Device name: Optima 2100DV manufactured by PerkinElmer

<< Evaluation 1 >>
(Polishing test)
Polishing equipment: Ebara: FREX300
Slurry: Planar Slurry
Work: Wafer with diameter 300 mm Metal (Cu) film Pad diameter: 740 mm
Pad break: 30N 30 minutes, diamond dresser polishing: surface plate rotation speed 70 rpm, head rotation speed 71 rpm, slurry flow rate 200 ml / min, polishing time: 60 seconds The polishing pads of Examples 1 to 6 and Comparative Examples 1 and 2 are described above. The polishing process was performed under the polishing conditions of the above, and the number of organic residues and the number of pad debris (pad debris) were measured and evaluated according to each evaluation standard. Then, the one having no C evaluation was used as an example, and the one having no C evaluation was used as a comparative example. The results are shown in Tables 7-8.

(Organic residue)
For organic residues, 35 substrates were polished by Metal (Cu) polishing, and the 35th substrate was measured in the high-sensitivity measurement mode of an unpatterned wafer surface inspection device (Surfscan SP2XP, manufactured by KLA Corporation). , The number of organic residues adhering to the substrate surface was observed.
The number of organic residues of 10 or less was evaluated as A, 11 or more and 20 or less was evaluated as B, and 21 or more was evaluated as C.

(Pad waste (pad debris))
For pad scraps, 35 substrates were polished by Metal (Cu) polishing, and the 35th substrate was measured in the high-sensitivity measurement mode of an unpatterned wafer surface inspection device (Surfscan SP2XP, manufactured by KLA Corporation). , The number of pad debris adhering to the substrate surface was observed.
Those with 10 or less pad scraps were evaluated as A, those with 11 or more and 20 or less were evaluated as B, and those with 21 or more were evaluated as C.

<< Evaluation 2 >>
Further, with respect to the polishing pads of Examples 1 to 6 and Comparative Examples 1 and 2, the polishing rate and the number of scratches were measured in addition to the number of organic residues and the number of pad debris (pad debris) under the above polishing conditions. The results are shown in Tables 7-8.

(Polishing rate)
The polishing rate is the amount of polishing per minute expressed in thickness (Å). The insulating film of the substrate before and after polishing was determined. The Cu film thickness was measured by a sheet resistance mapping system (RS-200 manufactured by KLA Corporation).
A polishing rate of 500 Å or more was evaluated as A, a polishing rate of 450 Å or more and less than 500 Å was evaluated as B, and a polishing rate of less than 450 Å was evaluated as C.

(scratch)
For scratches, 35 substrates were polished, and the 35th substrate was measured in the high-sensitivity measurement mode of an unpatterned wafer surface inspection device (Surfscan SP2XP, manufactured by KLA Corporation) to determine the number of scratches on the substrate surface. Observed.
Those with 4 or less scratches were evaluated as A, those with 5 to 8 were evaluated as B, and those with 9 or more were evaluated as C.

※１ カッコ内の数値はポリウレタン樹脂１００質量部に対する添加剤の含有量(質量部)を示す。

* 1 The value in parentheses indicates the content (parts by mass) of the additive with respect to 100 parts by mass of the polyurethane resin.

※２ カッコ内の数値はポリウレタン樹脂１００質量部に対する添加剤の含有量(質量部)を示す。

* 2 The values in parentheses indicate the content (parts by mass) of the additive with respect to 100 parts by mass of the polyurethane resin.

In the above table, "content (mg / kg)" and "content (mol / kg)" are the amount of calcium derived from the calcium salt contained in the polyurethane resin-containing solution, the filler or the polyurethane resin sheet, or the amount derived from the magnesium salt. The amount of magnesium is expressed in units of "mg / kg" and "mol / kg", respectively. The "converted value (mg / kg)" is a value obtained by converting the above-mentioned calcium amount or magnesium amount into the same molar amount of calcium carbonate.
In addition, "content (mg / L)" and "content (mol / L)" are the amount of calcium derived from the calcium salt or the amount of magnesium derived from the magnesium salt contained in the coagulation liquid as "mg / L" and respectively. It is expressed in the unit of "mol / L". The "converted value (mg / L)" is a value obtained by converting the amount of calcium or magnesium into the same molar amount of calcium carbonate.

As is clear from the results shown in Tables 5 to 8, the polishing pads of Comparative Examples 1 and 2 have a very large amount of hardness components of 209 mg / kg and 332 mg / kg contained in the polyurethane resin sheet, and have 20 or more. Organic residue was generated.
On the other hand, the polishing pads of Examples 1 to 6 have a hardness component content of 100 mg / kg or less in the polyurethane resin sheet, and are organically attached to the object to be polished as compared with the polishing pads of Comparative Examples 1 and 2. The amount of residue was significantly suppressed. In addition, the amount of pad waste adhered was small, and the scratching was also good. From the above, it was found that the polishing pads of Examples 1 to 6 had both convex defects and concave defects suppressed, and had a remarkable effect of reducing defects. Further, the polishing pads of Examples 1 to 6 were also good in terms of polishing rate.

According to the present invention, it is possible to provide a polishing pad capable of reducing the amount of organic residue adhering to the object to be polished. Therefore, it is extremely useful industrially.

Claims (9)

A polishing pad containing a wet-deposited polyurethane resin sheet.
The polyurethane resin sheet has a polished surface, and the amount of the hardness component which is a value obtained by converting the amount of calcium and magnesium derived from the calcium salt and the magnesium salt contained in the polyurethane resin sheet into the amount of calcium carbonate in the same molar amount. The polishing pad, which is 100 mg or less per 1 kg of the polyurethane resin sheet. The polishing pad according to claim 1, wherein the polyurethane resin sheet contains a polyurethane resin having a 100% modulus of 1 to 20 MPa. The polishing pad according to claim 1 or 2, wherein the polyurethane resin sheet contains a filler selected from the group consisting of carbon black and silica in a ratio of 0.1 to 30 parts by mass with respect to 100 parts by mass of the polyurethane resin. .. Any one of claims 1 to 3, wherein the value obtained by converting the amount of calcium derived from the calcium salt contained in the polyurethane resin sheet into the amount of calcium carbonate in the same mole is 70.0 mg or less per 1 kg of the polyurethane resin sheet. Polishing pad described in. Any one of claims 1 to 4, wherein the value obtained by converting the amount of magnesium derived from the magnesium salt contained in the polyurethane resin sheet into the amount of calcium carbonate in the same molar amount is 35.0 mg or less per 1 kg of the polyurethane resin sheet. Polishing pad described in. The polishing pad according to any one of claims 1 to 5, for polishing an object to be polished using a slurry containing an anionic surfactant. Step preparing a polyurethane resin and a solvent unrealized and good polyurethane resin-containing solution may contain a filler, and a polyurethane resin-containing solution immersed in a coagulation liquid to coagulate the polyurethane resin,
Including
The coagulation liquid hardness component concentration of calcium and magnesium concentration from calcium and magnesium salts are values in terms of the concentration of the same mole of calcium carbonate contained in the Ri Der below 60.0 mg / L, and
When the polyurethane resin-containing solution contains a filler, the hardness component concentration, which is a value obtained by converting the concentrations of calcium and magnesium derived from the filler contained in the polyurethane resin-containing solution into the same molar concentration of calcium carbonate, is the polyurethane resin-containing solution. Ru solids 1kg per 20.0mg der following method for producing a polishing pad according to any one of claims 1-6. The production method according to claim 7, wherein the polyurethane resin-containing solution contains 0 to 15 parts by mass of an anionic surfactant with respect to 100 parts by mass of the polyurethane resin. 7. Or 8 according to claim 7, wherein the polyurethane resin-containing solution contains at least one filler selected from the group consisting of carbon black and silica in a ratio of 0.1 to 30 parts by mass with respect to 100 parts by mass of the polyurethane resin. The manufacturing method described.