JP2018051645A - Polishing pad and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad capable of reducing an amount of organic residue attached to a surface of an object to be polished.SOLUTION: A polishing pad comprises a polyurethane resin sheet formed by a wet film formation method. The polyurethane resin sheet comprises: a polishing surface; and a calcium salt of 100 mg or less per 1 kg of the polyurethane sheet of a hardness component amount, which is a value equivalent to a calcium carbonate amount of the same mole, converted from amounts of the calcium salt and calcium and magnesium derived from the magnesium salt contained in the polyurethane resin sheet.SELECTED DRAWING: None

Description

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

  Since the surface of a material such as silicon, a hard disk, a mother glass for liquid crystal display, and a semiconductor device is required to be flat, a free abrasive grain type polishing using a polishing pad is performed. The free abrasive grain method is a method of polishing a processed surface of an object to be polished while supplying a slurry (polishing liquid) containing abrasive grains between a polishing pad and the object to be polished.

Polishing pads are broadly classified into hard and soft. The hard type is a dry method in which a urethane prepolymer is molded while chain-extending, and the soft type is a wet film-forming method in which a urethane resin solution is solidified and molded in a coagulation bath and dried. is there.
A hard polishing pad (dry polishing pad) is necessary to ensure the flatness of the substrate. However, since it is hard, defects such as scratches increase. For this reason, there are increasing cases of using a soft polishing pad (wet polishing pad) in which defects such as scratches are less likely to occur, mainly in the polishing process for finishing (Patent Document 1).

JP 2011-148082 A

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

  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 an organic residue hardly adheres to the surface of an object to be polished even when the object to be polished is polished. Another object of the present invention is to provide a polishing pad in which pad scraps hardly adhere to the surface of the object to be polished even when the object to be polished is polished.

As a result of diligent efforts, the present inventor has found that the adhesion of organic residues to the object to be polished is related to the hardness component contained in the polyurethane resin sheet, and the amount of 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 organic residue adhering to the object to be polished can be obtained by suppressing to the following. Further, the present inventor has found that the hardness component contained in the polyurethane resin sheet is mainly brought about by a coagulating liquid used for wet coagulation, and by using a coagulating liquid having a low hardness component concentration, polyurethane is obtained. It has been found that a polishing pad in which the amount of hardness component contained in the resin sheet is kept below a certain level and the amount of organic residues adhering to the object to be polished can be significantly reduced can be easily produced.
That is, the present invention provides the following.

<1> A polishing pad comprising a polyurethane resin sheet formed by wet film formation,
The polyurethane resin sheet has a polished surface, and the amount of 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 of the same mole. The polishing pad, which is 100 mg or less per 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> The polyurethane resin sheet contains 0.1 to 30 parts by mass of a filler selected from the group consisting of carbon black and silica with respect to 100 parts by mass of the polyurethane resin. <1> or <2> The polishing pad described in 1.
<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 the same mole of calcium carbonate is 70.0 mg or less per 1 kg of the polyurethane resin sheet, <1> to <3> A polishing pad according to any one of the above.
<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 the same mole of calcium carbonate is 35.0 mg or less per 1 kg of the polyurethane resin sheet, <1> to <4> A polishing pad according to any one of the above.
<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 coagulation liquid to solidify the polyurethane resin.
Including
<1> to <1> in which 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 coagulation liquid into the concentration of calcium carbonate of the same mole, is 60.0 mg / L or less. 6> The manufacturing method of the polishing pad in any one of.
<8> The method according to <7>, wherein the polyurethane resin-containing solution contains an anionic surfactant at a ratio of 0 to 15 parts by mass 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> Or the manufacturing method as described in <8>.

  ADVANTAGE OF THE INVENTION According to this invention, the polishing pad which can reduce significantly the adhesion amount to the to-be-polished object of an organic residue can be provided. In addition, the polishing pad of the present invention makes it difficult for pad scraps to adhere to the object to be polished even if the object to be polished is polished. Therefore, defects (defects) generated in an object to be polished such as a semiconductor device can be greatly reduced.

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

<Polyurethane resin sheet>
In the present specification and claims, a wet-formed polyurethane resin sheet is formed by wet coagulation of 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-formed polyurethane resin sheet has a plurality of tear-shaped bubbles. The tear-shaped bubble is a concept that means a bubble shape (having anisotropy and a structure having a large diameter from the polishing surface of the polishing pad toward the bottom) contained in a molded body formed by a wet method, It is used to distinguish from a normal bubble shape (isotropic, spherical, elliptical, or a shape close to these) present in a molded body molded by a dry film forming method. Therefore, the expression “wet-formed polyurethane resin sheet” can also be expressed as “a polyurethane resin sheet having a plurality of tear-shaped bubbles”.
The polyurethane resin sheet of the present invention has a polishing surface for polishing an object to be polished.

In the present specification, pad scraps are those generated by breaking a polyurethane resin sheet due to friction between the polyurethane resin sheet and an 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 matters such as soap scum derived from components such as surfactants contained in the polishing pad, and foreign matter such as soap scum derived from components in the slurry.

<Hardness component amount>
In the present specification and claims, the hardness component refers to calcium derived from calcium salt and magnesium derived from magnesium salt.
In the present specification and claims, calcium derived from calcium salt is a concept used to distinguish it from a metal consisting of simple calcium, and calcium salts such as calcium oxide, calcium acetate, calcium carbonate, and calcium sulfate are used. It means the constituent calcium (calcium ions).
In the present specification and claims, magnesium derived from a magnesium salt is a concept used to distinguish from a metal composed of a single element of magnesium, and constitutes a magnesium salt such as magnesium oxide, magnesium acetate, magnesium carbonate, and magnesium sulfate. Means magnesium (magnesium ion).
The polishing pad of the present invention has a value (hardness component amount) in which the amount (total amount) of calcium and magnesium derived from calcium salt and magnesium salt contained in the polyurethane resin sheet is converted to the amount of calcium carbonate of the same mole. It is 100 mg or less per 1 kg of the resin sheet.

In the present specification and claims, the amount of hardness component means that the amount of calcium derived from calcium salt and the amount of magnesium derived from magnesium salt are the same as the total amount of calcium and magnesium, as in the method of calculating the hardness of water. The value converted into the amount of calcium carbonate is calculated by the following formula (1).
Hardness component amount (mg / kg) = Ca content (mg / kg) × 2.496 + Mg content (mg / kg) × 4.119 (1)
The numerical value “2.496” in the above formula is a value calculated from the molecular weight of calcium carbonate / the molecular weight of calcium, and the numerical value “4.119” is calculated from the molecular weight of calcium carbonate / the molecular weight of magnesium. Value.

The amount of 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 the same mole of calcium carbonate, is preferably 80 mg / kg or less, and 70 mg / kg. It is more preferably not more than kg, still more preferably not more than 60 mg / kg, still more preferably not more than 50 mg / kg, and still more preferably not more than 40 mg / kg. 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, 10 mg / kg. It may be the above. When the hardness component amount is within the above range, the adhesion of organic residues 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 adhesion amount of the organic residue 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 becomes an interface in the wet polishing pad. It is presumed that this is because it binds to an activator or a surfactant in the slurry and forms a soap residue (a kind of organic residue) that is insoluble in water and has viscosity. As the amount of the soap residue 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 component, it is presumed that the generation of soap scum is suppressed, thereby reducing the amount of organic residues adhering to the object to be polished.

In the polishing pad of the present invention, the total amount of calcium and magnesium derived from the calcium salt and 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. 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 more preferably 5.0 × 10 ⁻⁴ mol / kg or less, still 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 calcium salt and 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 the same mole of calcium carbonate 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 of the same mole is more preferably 60.0 mg / kg or less, still more preferably 50.0 mg / kg or less, and 40.0 mg / kg or less. Is more preferably 30.0 mg / kg or less, still more preferably 20.0 mg / kg or less. The lower limit is not particularly limited. 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, 1 It may be 0.0 mg / kg or more.
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, and 4.0 × 10 ⁻⁴ mol. / Kg or less is even more preferable, 3.0 × 10 ⁻⁴ mol / kg or less is even more preferable, and 2.0 × 10 ⁻⁴ mol / kg or less is even more preferable. The lower limit is not particularly limited. 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, or 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 the same mole of calcium carbonate 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, still more preferably 25.0 mg / kg or less, and 20.0 mg / kg or less. Is more preferably 15.0 mg / kg or less, still 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, It may be 5 mg / kg or more.
In the polishing pad of the present invention, the amount of magnesium derived from a 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 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 preferable that the amount is not more than kg, still more preferably not more than 1.5 × 10 ⁻⁴ mol / kg, still more preferably not more than 1.0 × 10 ⁻⁴ mol / kg. The lower limit is not particularly limited. 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, or 0.5 × 10 ⁻⁵ mol / kg or more.
Content of calcium and / or magnesium derived from calcium salt and / or magnesium salt in polyurethane resin sheet, or calcium carbonate and / or magnesium derived from calcium salt and / or magnesium salt in polyurethane resin sheet in the same mole When the value converted into is within the above range, the amount of organic residue adhering to the object to be polished can be sufficiently reduced.

<(A) polyurethane resin>
There is no restriction | limiting in particular in the kind of polyurethane resin used as the material of the polyurethane resin sheet in the polishing pad of this invention, What is necessary is just to select according to a use purpose from various polyurethane resins. For example, a polyester-based, polyether-based, or polycarbonate-based resin can be used.
Examples of the polyester-based resin include a polymer of a polyester polyol such as ethylene glycol or butylene glycol and adipic acid and a diisocyanate such as diphenylmethane-4,4′-diisocyanate. Examples of polyether resins include polymers of polyether polyols such as polytetramethylene ether glycol and polypropylene glycol and isocyanates such as diphenylmethane-4,4′-diisocyanate. Examples of the polycarbonate-based resin include a polymer of polycarbonate polyol and isocyanate such as diphenylmethane-4,4′-diisocyanate. These resins are marketed in the market such as DIC Corporation's trade name “Chris Bon”, Sanyo Chemical Industries' product name “Samprene”, Dainichi Seika Kogyo's trade name “Rezamin”. Available resins may be used, and a resin having desired characteristics may be produced by itself.
Among these, polyester-based polyurethane resins that are excellent in film formation stability and mechanical properties are particularly preferable.

(100% modulus)
100% modulus (or resin modulus) is an index that represents the hardness of the resin, and the load applied when a non-foamed resin sheet is stretched 100% (when it is stretched twice the original length) is cut off. It is a value divided by the area (hereinafter sometimes referred to as resin modulus). The higher this value, the harder the resin.
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, from the appropriate elastic characteristics required of the polishing pad, an effect that the object to be polished can be polished efficiently and with high quality is obtained, and there is an effect of reducing scratches.

<(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 the polyurethane resin sheet.
The 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 with respect to 100 parts by mass of the polyurethane resin. More preferably, it is contained, more preferably 1-15 parts by mass, even more preferably 2-10 parts by mass. A polishing rate can be improved as the ratio of the said filler exists in the said range. Moreover, the dressability of the surface can be improved by imparting brittleness.

The particle diameter (dispersion diameter) of fillers 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. It is preferable for the particle diameter to be in the above range because the rigidity of the polyurethane resin sheet can be improved and scratches during polishing can be effectively suppressed.
The particle diameter of the filler can be measured using a dynamic light scattering method. More specifically, the particle diameter of the filler is a particle diameter in a dispersed state measured using a dynamic light scattering method. Hereinafter, the particle diameter of the filler may be referred to as a dispersion diameter.

  In the polishing pad of the present invention, a filler other than carbon black and / or silica may be used in combination with carbon black and / or silica as long as the effects of the present invention are not impaired. Examples of the other filler include organic pigments such as azo pigments and inorganic pigments such as titanium oxide.

<(C) Other optional components>
The polishing pad of the present invention includes, in addition to the above components, a foaming aid, a crosslinking agent, a dispersant, a water repellent, a film forming stabilizer, etc. Additives may be included. Examples of the foaming aid include anionic surfactants, nonionic surfactants, and amphoteric surfactants. Among these, anionic surfactants are preferable to form large foams, fatty acid-based anionic surfactants are more preferable, sodium salts and potassium salts of higher fatty acids are preferable, such as sodium lauryl sulfate. And sodium salts of mono long chains of sulfuric acid (preferably C8-C18, more preferably C10-C14) alkyl esters.

In the polishing pad of the present invention, the polishing surface of the polyurethane resin sheet and / or the surface opposite to the polishing surface may be ground (buffed). Among these, it is preferable that the polishing surface of the polyurethane resin sheet of the polishing pad of the present invention is ground. Thereby, many openings derived from microbubbles exist on the polishing surface, and the polishing rate is improved by holding the slurry in the openings.
In the polishing pad of the present invention, the polishing surface of the polyurethane resin sheet may be subjected to groove processing, embossing and / or hole processing (punching processing). The polishing pad of the present invention may include a light transmission part.

<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) for polishing the object to be polished. . As the other layer, a layer having a Shore A hardness larger than that of the polyurethane resin sheet is preferably used. By providing another layer, the profile (surface and end shape) of the substrate can be adjusted.
Other layers include non-woven fabrics, plastic sheets, rubber, sponges and the like.
The thickness of the other layers is not particularly limited, but is preferably 0.1 to 3 mm, more preferably about 0.15 to 2 mm without being subjected to mechanical restrictions of the polishing mechanism, and the polishing constant. The influence of the board can be made sufficiently small.

  When the polishing pad forms a multilayer structure, a plurality of layers may be bonded and fixed using a double-sided tape, an adhesive, or the like while being pressurized and heated as necessary. There is no restriction | limiting in particular in the double-sided tape and adhesive used at this time, It can select and use arbitrarily from well-known double-sided tapes and adhesives in this technical field. Further, it is possible to use a direct coating method in which a polishing layer is directly formed on a substrate without using a double-sided tape or an adhesive.

<Physical properties of polyurethane resin sheet>
(Thickness)
Although there is no restriction | limiting in particular in the thickness of the polyurethane resin sheet in the polishing pad of this invention, It is preferable that it is about 0.3-2 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 compressibility is an index of the softness of the polishing pad.
The compression rate can be determined using a shopper type thickness measuring instrument (pressure surface: circular shape with a diameter of 1 cm) in accordance with Japanese Industrial Standard (JIS L 1021). Specifically, it is as follows.
The thickness t0 after applying the initial load for 30 seconds from the no-load state is measured, and then the thickness t1 after applying the final pressure for 30 seconds from the state of thickness t0 is measured. The compression rate can be calculated by the equation 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 rate of 1 to 70%, more preferably 3 to 60%, still more preferably 4 to 40%, and even more preferably 5 to 20%. % Is particularly preferred. When the compression rate is within the above range, the scratch performance and the polishing rate are well balanced.

(Compressive modulus)
In the present specification, the compression elastic modulus is an index of ease of return to the compression deformation of the polishing pad or the polyurethane resin sheet.
The compression elastic modulus can be determined using a shopper type thickness measuring instrument (pressure surface: circular shape with a diameter of 1 cm) in accordance with Japanese Industrial Standard (JIS L 1021). Specifically, it is as follows.
The thickness t ₀ after the initial load is applied for 30 seconds from the unloaded state is measured, and then the thickness t ₁ after the final load is applied for 5 minutes from the state of the thickness t ₀ is measured. Next, all loads are removed from the state of the thickness t ₁ , and after leaving for 5 minutes (no load state), the thickness t ₀ ′ after the initial load is again applied for 30 seconds is measured. The compressive elastic modulus can be calculated by the equation of compressive elastic modulus (%) = 100 × (t ₀ ′ −t ₁ ) / (t ₀ −t ₁ ) (Note that the initial load is 100 g / cm ² , and the final The load is 1120 g / cm ² ).
The polyurethane resin sheet in the polishing pad of the present invention preferably has a compression modulus (%) of 50 to 100%, more preferably 70 to 100%, and even more preferably 80 to 100%. preferable. When the compression elastic modulus is within the above range, the deformation of the pad due to the polishing load can be reduced, and a stable state of the polishing characteristics can be maintained.

(Shore A hardness)
In this 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, and still more preferably 10 to 35 degrees. It is particularly more preferable that the angle is 30 degrees. When the Shore A hardness is within the above range, the balance between the scratch performance and the polishing rate is good.

(Average hole diameter)
In this specification, the average hole diameter is an average value of equivalent circle diameters calculated from the area and the number of each hole portion obtained by binarizing the surface image of the polishing pad or the polyurethane resin sheet.
The average pore 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 diameter is within the above range, the slurry has good retention and a stable polishing rate can be obtained.

(Aperture ratio)
In this specification, the hole area ratio means the ratio (%) of the hole area to the surface (polishing surface) of the polishing pad or polyurethane resin sheet.
The porosity 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 open area ratio is within the above range, the slurry has good retention and a stable polishing rate can be obtained.

<Physical properties of polishing pad>
(Thickness)
Although there is no restriction | limiting in particular in the thickness of the polishing pad of this invention, It is preferable that it is about 0.5-3 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 balance between the polishing rate and the scratch performance is good.

(Compression rate)
The polishing pad of the present invention preferably has a compression ratio measured under the above conditions of 10 to 70%, more preferably 15 to 55%, still more preferably 20 to 50%, It is especially preferable that it is 25 to 45%. When the compression rate is within the above range, the balance between the polishing rate and the scratch performance is good.

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

(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 still more preferably 15 to 30 degrees. When the Shore A hardness is within the above range, the balance between the polishing rate and the scratch performance is good.

(Use)
The polishing pad of the present invention can be suitably used for polishing silicon, a hard disk, a mother glass for liquid crystal display, a semiconductor device, and a cover glass, particularly 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 workpiece to be processed by the polishing pad of the present invention include a glass substrate for hard disk, an aluminum substrate, a mother glass for LCD, a semiconductor wafer, a semiconductor device, and a cover glass. Especially, the polishing pad of this invention is used suitably for processing a semiconductor device.
There is no restriction | limiting in particular in the kind of slurry used in order to grind | polish a to-be-polished object using the polishing pad of this invention, For example, the slurry etc. which contain surfactant and / or an abrasive grain 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 and magnesium derived from the calcium salt and magnesium salt contained in the polyurethane resin sheet is reduced, a surfactant (for example, an anionic surfactant) is contained in the slurry. Even in this case, the organic residue (soap residue) is hardly formed during the polishing of the object to be polished, and the adhesion amount of the organic residue to the object to be polished can be reduced. Therefore, the slurry can be freely selected and used according to the application without being restricted by the kind of the additive in the slurry.
The polishing pad of the present invention can be preferably produced by the following method.

<< Production 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 solidifying the polyurethane resin by immersing the polyurethane resin-containing solution in a coagulation liquid, and the coagulation. The hardness component concentration, which is a value obtained by converting the concentration of calcium and magnesium derived from calcium salt and magnesium salt into the concentration of calcium carbonate of the same mole, is 60.0 mg / L or less.

<Hardness component concentration>
In the present specification and claims, the hardness component concentration refers to the concentration of calcium and magnesium derived from the calcium salt and magnesium salt contained in the solution to the same concentration of calcium carbonate as the total of the calcium and magnesium. This is a converted value and is calculated by the following equation (2).
Hardness component concentration (mg / L) = Ca concentration (mg / L) × 2.496 + Mg concentration (mg / L) × 4.119 (2)
The numerical value “2.496” in the above formula is a value calculated from the molecular weight of calcium carbonate / the molecular weight of calcium, and the numerical value “4.119” is calculated from the molecular weight of calcium carbonate / the molecular weight of magnesium. Value.
In the above, the hardness component concentration is defined in mg / L. However, when the mass of the solution is clear, the hardness component concentration may be defined in mass per kg of the solution, that is, mg / kg.
The calcium derived from the calcium salt and the magnesium derived from the magnesium salt contained in the coagulating liquid may be present in the coagulating liquid as calcium ions and magnesium ions, respectively, or may be present in the coagulating liquid as a salt with an anion. Good.
Hereinafter, each process of the manufacturing method of this invention is demonstrated.

<Preparation process of resin solution>
In this preparation step, the polyurethane resin is added to and mixed with a solvent (hereinafter sometimes referred to as solvent 1) to prepare a polyurethane resin-containing solution containing the polyurethane resin and the solvent.
(Polyurethane resin)
As the polyurethane resin as a raw material, 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)
As a solvent for dissolving the resin, N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), acetone, acetonitrile, N-methylpyrrolidone ( NMP) and the like and mixtures thereof. Among these, DMF is preferable. Foaming is formed by replacing the organic solvent having polarity in the urethane resin solution with water in the coagulating liquid during coagulation.

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

  The polyurethane resin-containing solution may contain fillers, additives and the like in addition to the above components. The filler or additive may be added to the solvent before the polyurethane resin is dissolved in the solvent, or may be added to a 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 the 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. Preferably, 1 to 15 parts by mass is further included, and 2 to 10 parts by mass is even more preferable. When the ratio of the filler is within the above range, the polishing rate of the obtained polishing pad can be improved. Moreover, the dressability of the surface can be improved by imparting brittleness.

The filler may be mixed with a component such as polyurethane resin or solvent 1 in the form of a dispersion dispersed in a solvent (hereinafter sometimes referred to as 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 mixing with the polyurethane resin and the solvent 1 in the form of a dispersion in which the filler is dispersed in the solvent 2, the amount of the hardness component derived from the filler 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, there is an effect 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 amount of the hardness component derived from the filler contained in the polyurethane resin-containing solution. For example, it may be 0 mg or more per kg of the 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.

Further, the total concentration of calcium and magnesium derived from the filler and calcium salt derived from the filler contained in the polyurethane resin-containing solution is 2.0 × 10 ⁻⁴ mol or less per 1 kg of the solid content of the polyurethane resin-containing solution. Is preferably 1.5 × 10 ⁻⁴ mol or less, and more preferably 1.0 × 10 ⁻⁴ mol or less. There is no particular limitation on the lower limit of the total concentration of calcium and magnesium derived from the filler and calcium salt derived from the filler contained in the polyurethane resin-containing solution, for example, 0 mol or more per kg 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 derived from the calcium salt and the magnesium derived from the magnesium salt 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 inside.

Moreover, when mixing a filler with a polyurethane resin and the solvent 1 in the form of a dispersion liquid, the value which converted the quantity of calcium derived from the calcium salt contained in a filler into the quantity of calcium carbonate of the same mole is 150 mg or less per 1 kg of filler. Preferably, it is 120 mg or less, 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.
There is no particular limitation on 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 the same mole of calcium carbonate. For example, it may be 0 mg or more per 1 kg of the dispersion, 0.1 mg The above may be sufficient, 0.5 mg or more may be sufficient, and 1.0 mg or more may be sufficient.

Further, 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 filler, Even more preferably, it is 0.6 × 10 ⁻³ mol or less. There is no restriction | limiting in particular in the lower limit of the quantity of calcium derived from the calcium salt contained in a filler, For example, it may be 0 mol or more per kg of filler, may be 0.1 * 10 < ^-5 > mol or more, 0 may also be .5 × 10 ^-5 mol or more, it may be 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, the value obtained by converting the amount of magnesium derived from the magnesium salt contained in the filler into the amount of the same mole of calcium carbonate is 80 mg or less per 1 kg of filler. It is preferably 50 mg or less, more preferably 30 mg or less. When the value obtained by converting the amount of magnesium into the amount of calcium carbonate of 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 the same mole of calcium carbonate. For example, it may be 0 mg or more per 1 kg of filler, 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 per kg of filler. Even more preferably, it is 3 × 10 ⁻³ mol or less. There is no restriction | limiting in particular in the lower limit of the quantity of magnesium derived from the magnesium salt contained in a filler, For example, it may be 0 mol or more per kg of filler, may be 0.1 * 10 < ^-5 > mol or more, 0 may also be .5 × 10 ^-5 mol or more, it may be 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 to form large foams, fatty acid-based anionic surfactants are more preferable, sodium salts and potassium salts of higher fatty acids are preferable, such as sodium lauryl sulfate. And sodium salts of mono long chains of sulfuric acid (preferably C8-C18, more preferably C10-C14) alkyl esters.
The anionic surfactant is preferably contained in the polyurethane resin solution at a ratio of 0 to 15 parts by mass with respect to 100 parts by mass of the polyurethane resin, preferably 0.1 to 15 parts by mass, and 1 to 12 parts by mass. More preferred. When the content of the anionic surfactant is within the above range, foaming can be increased during wet coagulation. Furthermore, the film formability can be improved. In addition, when an anionic surfactant is used in the manufacturing process of a conventional polishing pad, a soap residue may be generated by combining with calcium derived from a calcium salt and magnesium derived from a magnesium salt contained in a 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 coagulation liquid are greatly reduced, so that even when an anionic surfactant is used, the amount of soap residue generated can be suppressed. The amount of organic residue attached to the object to be polished can be reduced.
Foaming aids and film stabilizers generally contain few calcium and magnesium-derived components derived from calcium salts and magnesium salts, but are derived from calcium salts and magnesium salts in foaming aids and film stabilizers. 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 film forming stabilizer are It is preferable to adjust so that it may become below each density | concentration contained in.

<Application process>
The polyurethane resin-containing solution obtained in the preparation step is applied onto a film forming substrate. There is no restriction | limiting in particular in the application | coating method, What is necessary is just to apply | coat continuously the polyurethane resin containing solution on a film-forming base material by a knife coater, a reverse coater, etc., for example. As a film-forming substrate, any substrate that is usually used in this technical field can be used without any particular limitation. Examples include a flexible polymer film such as a polyester film and a polyolefin film, a nonwoven fabric impregnated and fixed with an elastic resin, and a polyester film is preferably used among them.

<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 in which a polyurethane resin is coagulated and regenerated by immersing a substrate coated with a polyurethane resin-containing solution in a coagulation liquid mainly composed of water, which is a poor solvent for the polyurethane resin. is there. In the coagulation liquid, the solvent (for example, DMF) of the polyurethane resin-containing solution is replaced with the coagulation liquid, and the polyurethane resin is coagulated and regenerated. In wet coagulation, when immersed in a coagulation liquid, a surface film called a skin layer is formed at the interface, and the resin coagulates through substitution of the solvent in the resin solution and the coagulation liquid. Since coagulation proceeds from the skin layer to the inside, teardrop-like foaming peculiar to wet coagulation, which increases from the skin layer side to the inside, is formed in the thickness direction.
As the coagulation 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, methanol and the like. The concentration of the polar solvent in the coagulation liquid is preferably 0 to 20% by mass.
There is no restriction | limiting in particular in the temperature and immersion time of a coagulation liquid, For example, what is necessary is just to immerse for 10 to 100 minutes at 15-50 degreeC.

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 mole, is 60 mg or less per liter of coagulation liquid, and 45 mg or less. It is preferable that it is 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 coagulated 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 may be, for example, 0 mg or more, 1 mg or more, 0.5 mg or more, 1.0 mg or more per liter of the coagulation liquid. It may be.

The total concentration of calcium and magnesium derived from the calcium salt and magnesium salt contained in the coagulation liquid is preferably 6.0 × 10 ⁻⁴ mol or less per liter of the coagulation bath, and 4.5 × 10 ⁻⁴ mol. More preferably, it is more preferably 3.0 × 10 ⁻⁴ mol or less. The lower limit of the total concentration of 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 liter of the coagulating liquid, 0.1 × 10 ⁻⁵ mol may be more, may also be 0.5 × 10 ^-5 mol or more, it may be 1.0 × 10 ^-5 mol or more.

The value obtained by converting the calcium salt-derived calcium concentration contained in the coagulation liquid into the same molar calcium carbonate concentration is preferably 44.0 mg or less, preferably 40.0 mg or less per liter of coagulation liquid. More preferably, it is 20.0 mg or less. When the value obtained by converting the concentration of calcium derived from the calcium salt into the concentration of calcium carbonate of the same mole is within the above range, there is an effect in reducing the amount of organic residue attached 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 of the same mole, and for example, it may be 0 mg or more per liter of the coagulation liquid, or may be 0.1 mg or more , 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 liter of coagulation bath, and more preferably 4.0 × 10 ⁻⁴ mol or less. Preferably, it is 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 per liter of coagulation liquid, or 0.1 × 10 ⁻⁵ mol or more. 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 coagulation liquid into the concentration of the same mole of calcium carbonate is preferably less than 19.5 mg per liter of coagulation liquid, and more preferably 19.0 mg or less. Preferably it is 10.0 mg or less. When the value obtained by converting the concentration of magnesium derived from a 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 value of the value obtained by converting the magnesium concentration derived from the magnesium salt into the concentration of the same mole of calcium carbonate. For example, it may be 0 mg or more, or 0.1 mg or more per liter of 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 liter of coagulation liquid, and more preferably 1.9 × 10 ⁻⁴ mol or less. Preferably, it is 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 per liter of coagulation liquid, or 0.1 × 10 ⁻⁵ mol or more. 0.5 × 10 ⁻⁵ mol or more, or 1.0 × 10 ⁻⁵ mol or more.
As a method of bringing the hardness component concentration, calcium concentration and / or magnesium concentration of the coagulation liquid into the above range, for example, after preparing the coagulation liquid, a method of treating the coagulation liquid using an ultrafiltration membrane or a reverse osmosis membrane Is mentioned. As a pore diameter of an ultrafiltration membrane and a reverse osmosis membrane, 0.0001-0.1 micrometer is preferable, 0.0005-0.05 micrometer is more preferable, 0.001-0.02 micrometer is still more preferable, 0.001- 0.005 μm is particularly preferable. As long as the hardness component concentration of the coagulation liquid is within the above range, ion-exchanged water (soft water) or the like can be applied.

  When the hardness component concentration of the coagulating liquid is high, the polyurethane resin sheet contains a large amount of calcium and magnesium due to substitution by wet coagulation. In the process of preparing a polyurethane resin-containing solution, an anionic surfactant such as a higher fatty acid sodium salt may be added as a foaming aid to form and adjust foaming. Although it elutes into the liquid, a part remains in the polyurethane resin sheet. At this time, when calcium and magnesium derived from calcium salt and magnesium salt are contained in the coagulating liquid, sodium derived from sodium salt of an anionic surfactant is dissolved in the coagulating liquid. By substituting calcium and magnesium derived from it, it is considered that soap scum that is insoluble in water and has viscosity is formed and tends to remain in the polyurethane resin sheet. This soap residue is insoluble in water and adheres to the object to be polished as an organic residue during polishing. As a result, convex defects are increased. The present invention can reduce the formation of soap scum by reducing the hardness component concentration of the coagulating liquid, and can improve the problem that the organic residue adheres to the object to be polished and causes a convex defect.

<Washing and drying process>
The sheet-like polyurethane resin obtained by coagulation with a coagulation liquid is washed and dried.
The solvent remaining in the polyurethane resin-containing solution is removed by the washing treatment. An example of the cleaning liquid used for cleaning is water. For the purpose of further reducing the amount of calcium and magnesium derived from the calcium salt and magnesium salt contained in the polyurethane resin sheet, washing with dilute acid, chelate washing, neutralization washing, washing with pure water, etc. may be added. . If the cleaning solution contains a large amount of calcium and magnesium derived from the calcium salt and magnesium salt, adjust the hardness component concentration, calcium concentration, and magnesium concentration of the cleaning solution to be equal to or less than the respective concentrations contained in the coagulation solution. It is preferable.
After washing, the polyurethane resin is dried. What is necessary is just to perform the drying process by the method currently performed, for example, what is necessary is just to dry in a dryer for about 5 to 30 minutes at 100-180 degreeC. A polyurethane resin sheet can be obtained through the above steps. Also, squeeze out the washing solution as much as possible before drying, and dry it after reducing the water of the coagulation solution containing calcium salt and magnesium derived from calcium salt and magnesium salt and water of the washing solution as much as possible. The amount of hardness component to be reduced can be reduced.

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

<Multilayer formation process>
The manufacturing method of this invention may have the process of bonding a polyurethane resin sheet with another layer (lower layer, support layer) on the surface on the opposite side to the grinding | polishing surface of a polyurethane resin sheet. Examples of the other layer include other layers described in the above section << Polishing pad >>. As a method for bonding to other layers, for example, a polyurethane resin sheet and other layers may be bonded and fixed using a double-sided tape, an adhesive or the like while applying pressure as necessary. There is no restriction | limiting in particular in the double-sided tape and adhesive used at this time, It can select and use arbitrarily from well-known double-sided tapes and adhesives in this technical field.

Furthermore, the polishing pad of the present invention may be subjected to grinding treatment on the surface and / or back surface of the polishing layer, or grooving or embossing on the surface as necessary. May be bonded to the polishing layer, and a light transmission part may be provided.
There is no restriction | limiting in particular in the method of a grinding process, It can grind by a well-known method. Specific examples include grinding with sandpaper. As a result, a suede-like polished surface can be obtained.
There is no restriction | limiting in particular in the shape of groove processing and embossing, For example, shapes, such as a lattice type, a concentric circle type, and a radiation type, are mentioned.

<< Manufacture of polishing pad >>
The polishing pad of Examples 1-6 and Comparative Examples 1-2 was manufactured using the following materials and manufacturing methods. The composition of the polyurethane resin containing solution used when manufacturing the polishing pad of each Example and Comparative Example is shown in Tables 1-2. Moreover, the calcium concentration and magnesium concentration derived from the calcium salt and magnesium salt contained in the coagulation liquid used at the coagulation process are shown in Tables 3-4.

<Example 1>
(1) Resin Solution Preparation Step A 30% by mass polyurethane resin-containing solution in which a polyester polyurethane resin (100% modulus: 6 MPa) was dissolved in N, N-dimethylformamide (DMF) was prepared.
(2) Coating process The polyurethane resin-containing solution was coated almost uniformly on a belt-shaped film-forming substrate (polyethylene terephthalate) with a coating device such as a knife coater at room temperature.
(3) Coagulation step Coagulating liquid (hardness component concentration) obtained by treating the polyurethane resin-containing solution applied on the film-forming substrate obtained in (2) with an ultrafiltration membrane (pore diameter: 0.01 μm) Was 58.6 mg / L of water) and wet coagulated at 18 ° C. for 75 minutes. Thereby, the polyurethane resin sheet was formed on the film-forming substrate.
(4) Washing and drying step The polyurethane resin sheet was peeled 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. Thereafter, the polyurethane resin sheet was dried at 135 ° C. for 10 minutes using a dryer.
(5) Buff treatment step After drying, the buff treatment was performed on the skin layer side formed on the surface of the obtained polyurethane resin sheet.
(6) Bonding process The base material (polyethylene terephthalate resin sheet having a thickness of 188 μm) and the buffed surface of the buffed polyurethane resin sheet were bonded to each other using an adhesive.
(7) Lamination process The double-sided tape was bonded together to the surface on the opposite side to the surface bonded with the polyurethane resin sheet of a base material.
(8) Embossing process After sandwiching a wire mesh having a grid-like embossing pattern and a polyurethane resin sheet on which a base material and a double-sided tape are bonded together with a heat platen on the upper and lower sides, hot pressing was performed to buff the polyurethane resin sheet. An uneven embossing corresponding to the wire mesh lattice was formed on the surface to obtain the polishing pad of Example 1.

<Example 2>
(1) Resin Solution Preparation Step In N, N-dimethylformamide (DMF), a 30% by mass polyester-based polyurethane resin (100% modulus: 6 MPa) solution and 20% by mass silica (product name GO #, manufactured by Mikuni Dye Co., Ltd.) 2167 (primary particle diameter (average): 169 nm, dispersion diameter: 256 nm)) A DMF dispersion was mixed so that a 30 mass% polyurethane resin solution: DMF: 20 mass% silica DMF dispersion = 100: 41: 12. A polyurethane resin-containing solution was prepared.
(2) Coating process The polyurethane resin-containing solution was coated almost uniformly on a belt-shaped film-forming substrate (polyethylene terephthalate) with a coating device such as a knife coater at room temperature.
(3) Coagulation step Coagulating liquid (hardness component concentration) obtained by treating the polyurethane resin-containing solution applied on the film-forming substrate obtained in (2) with an ultrafiltration membrane (pore diameter: 0.01 μm) Was 58.6 mg / L of water) and wet coagulated at 18 ° C. for 75 minutes. Thereby, the polyurethane resin sheet was formed on the film-forming substrate.
(4) Washing and drying step The polyurethane resin sheet was peeled 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. Thereafter, the polyurethane resin sheet was dried at 135 ° C. for 10 minutes using a dryer.
(5) Buff treatment step After drying, the buff treatment was performed on the skin layer side formed on the surface of the obtained polyurethane resin sheet.
(6) Bonding process The base material (polyethylene terephthalate resin sheet having a thickness of 188 μm) and the buffed surface of the buffed polyurethane resin sheet were bonded to each other using an adhesive.
(7) Lamination process The double-sided tape was bonded together to the surface on the opposite side to the surface bonded with the polyurethane resin sheet of a base material.
(8) Embossing process After sandwiching a wire mesh having a grid-like embossing pattern and a polyurethane resin sheet on which a base material and a double-sided tape are bonded together with a heat platen on the upper and lower sides, hot pressing was performed to buff the polyurethane resin sheet. An uneven embossing corresponding to the wire mesh lattice was formed on the surface to obtain a polishing pad of Example 2.

<Example 3>
In step (1), 30% by mass polyester resin 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. A polishing pad of Example 3 was obtained in the same manner as in Example 2 except that a resin (100% modulus: 6 MPa) solution and a 20 mass% silica DMF dispersion were mixed.

<Example 4>
In the step (1), a polyurethane resin having a 100% modulus of 12 MPa is used for a 30% by mass polyester-based polyurethane resin solution, and 1 part by mass of sodium lauryl sulfate (Nikko) is added as an additive to 100 parts by mass of the 30% by mass polyurethane resin solution. Chemical Example, product name NIKKOL SLS) was mixed in the same manner 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. A polishing pad was obtained.

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

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

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

<Comparative example 2>
In the step (1), instead of the 20% by mass silica DMF dispersion, 15% by mass carbon black (manufactured by DIC, product name Dirac black (primary particle size (average): 22 nm, dispersion size: 375 nm)) DMF The dispersion is used in an amount of 35 parts by mass with respect to 100 parts by mass of a 30% by mass polyurethane resin solution, and 5 parts by mass of sodium lauryl sulfate (product of Nikko Chemicals, product) with respect to 100 parts by mass of the 30% by mass polyurethane resin solution. The polishing of Comparative Example 2 was performed in the same manner as in Example 2 except that the mixture was mixed using the name NIKKOL SLS) (mixed using 16.7 parts by mass of sodium lauryl sulfate with respect to 100 parts by mass of polyurethane resin). I got a pad.

<< Physical properties >>
About the polishing pad of Examples 1-6 and Comparative Examples 1-2, the physical properties (thickness, density, compressibility, compression elastic modulus, Shore A hardness, average aperture diameter, aperture ratio) of the polyurethane resin sheet were as follows. , Calcium salt and magnesium amount derived from calcium salt and magnesium salt) and physical properties of the polishing pad (thickness, density, compression rate, compression modulus, Shore A hardness). The results are shown in Tables 5-8.

(Density g / cm ³ )
The density is determined by the following formula after cutting a sample piece (10 cm × 10 cm) from a polishing pad or a polyurethane resin sheet and measuring the mass of the sample piece with an automatic balance.
Density (g / cm ³ ) = mass (g) / (10 cm × 10 cm × sample piece thickness cm)
It was measured by.

(Compression rate%, compression modulus%)
The compressibility and the compressive elastic modulus were measured using a shopper type thickness measuring instrument (pressure surface: circular shape with a diameter of 1 cm) in accordance with JISL1021. Specifically, the thickness t0 after applying the initial load for 30 seconds from the no-load state was measured, and then the thickness t1 after applying the final pressure from the state of thickness t0 for 30 seconds was measured. All loads were removed from the state of thickness t1, and after standing for 5 minutes (no load state), the thickness t0 ′ after applying the initial load again for 30 seconds was measured.
Compression rate (%) = 100 × (t0−t1) / t0
Compression 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 the Shore A hardness, a sample piece (10 cm × 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. , JISK7311).

(Average hole diameter, hole area ratio)
The average hole diameter and the hole area ratio were measured by magnifying the polished surface of the polyurethane resin sheet 100 times with a scanning electron microscope (JEOL Co., Ltd., JMS-5500LV) and observing 9 places. The calculation was performed by binarization using processing software (Image Analyzer V20LAB Ver. 1.3, manufactured by Nikon Corporation).

(Calcium content and magnesium content)
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. Covered with a watch glass and heated to decompose the organic components and heated until the solution was small. After standing to cool, 3 ml of hydrogen peroxide was added and reheated until the liquid became small. The sample was made up to 50 ml with 1N nitric acid while filtering through filter paper.
And using this sample, content of calcium and magnesium derived from calcium salt and magnesium salt was measured by an analyzer.
Analysis method: ICP emission spectroscopic analysis device name: Optima 2100DV manufactured by PerkinElmer

<< Evaluation 1 >>
(Polishing test)
Polishing apparatus: Ebara Corporation: F REX300
Slurry: Planar's Slurry
Workpiece: 300mm diameter wafer with Metal (Cu) film Pad diameter: 740mm
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 About the polishing pads of Examples 1 to 6 and Comparative Examples 1 and 2 above Polishing was performed under the above polishing conditions, and the number of organic residues and the number of pad debris (pad debris) were measured and evaluated according to each evaluation standard. And the thing which has no C evaluation was made into the Example, and the thing with even one C evaluation was made into the 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 a high sensitivity measurement mode of a patternless wafer surface inspection device (Surfscan SP2XP, manufactured by KLA Tencor). The number of organic residues adhering to the substrate surface was observed.
Those having 10 or less organic residues were evaluated as A, those having 11 or more and 20 or less were evaluated as B, and those having 21 or more as C evaluation.

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

<< Evaluation 2 >>
Moreover, about the polishing pad of Examples 1-6 and Comparative Examples 1-2, it measured about a polishing rate and the number of scratches on said grinding | polishing conditions other than the number of organic residues and the number of pad debris (pad debris). 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. In addition, Cu film thickness measurement was measured with the sheet resistance mapping system (the KLA Tencor company make, RS-200).
Polishing rates of 500 mm or more were evaluated as A, those having a polishing rate of 450 mm or more and less than 500 mm were evaluated as B, and those whose polishing rate was less than 450 mm were evaluated as C.

(scratch)
For the scratch, the 35th substrate was polished, and the 35th substrate was measured in the high sensitivity measurement mode of the pattern-less wafer surface inspection device (Surfscan SP2XP, manufactured by KLA Tencor), and the number of scratches on the substrate surface was measured. Observed.
A rating of 4 or less scratches was A, 5 to 8 was rated B, and 9 or more was rated 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 additive content (parts by mass) relative 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 Figures in parentheses indicate the additive content (parts by mass) relative to 100 parts by mass of polyurethane resin.

In the above table, “content (mg / kg)” and “content (mol / kg)” are derived from the calcium salt or magnesium salt derived from the calcium salt contained in the polyurethane resin-containing solution, filler or polyurethane resin sheet. 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 calcium amount or magnesium amount into the same amount of calcium carbonate.
In addition, “content (mg / L)” and “content (mol / L)” indicate the calcium amount derived from the calcium salt or the magnesium amount derived from the magnesium salt contained in the coagulation liquid, respectively “mg / L” and Expressed in units of “mol / L”. The “converted value (mg / L)” is a value obtained by converting the calcium amount or the magnesium amount into a calcium carbonate concentration of the same mole.

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 component 209 mg / kg and 332 mg / kg contained in the polyurethane resin sheet, and 20 or more An organic residue was generated.
In contrast, in the polishing pads of Examples 1 to 6, the amount of hardness component contained in the polyurethane resin sheet is 100 mg / kg or less, and compared with the polishing pads of Comparative Examples 1 and 2, the organic material adhered to the object to be polished. The amount of residue was remarkably suppressed. Also, the amount of pad scraps attached was small, and the scratch was also good. From the above, it was found that the polishing pads of Examples 1 to 6 have a remarkable defect reducing effect because both the convex defects and the concave defects are suppressed. Furthermore, the polishing pads of Examples 1 to 6 were good in terms of polishing rate.

  ADVANTAGE OF THE INVENTION According to this invention, the polishing pad which can reduce the quantity of the organic residue adhering to a to-be-polished object can be provided. Therefore, it is very useful industrially.

Claims (9)

A polishing pad comprising a polyurethane resin sheet wet-formed,
The polyurethane resin sheet has a polished surface, and the amount of 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 of the same mole. The polishing pad, which is 100 mg or less per kg of the polyurethane resin sheet.   The polishing pad according to claim 1, wherein the polyurethane resin sheet comprises 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 0.1 to 30 parts by mass of a filler selected from the group consisting of carbon black and silica with respect to 100 parts by mass of the polyurethane resin. .   The value which converted the quantity of calcium derived from the calcium salt contained in the said polyurethane resin sheet into the quantity of the calcium carbonate of the same mole is 70.0 mg or less per 1 kg of polyurethane resin sheets. The polishing pad described in 1.   The value which converted the quantity of magnesium derived from the magnesium salt contained in the said polyurethane resin sheet into the quantity of the calcium carbonate of the same mole is 35.0 mg or less per kg of polyurethane resin sheets, Any one of Claims 1-4. The polishing pad described in 1.   The polishing pad of any one of Claims 1-5 for grind | polishing a to-be-polished object using the slurry containing an anionic surfactant. A step of preparing a polyurethane resin-containing solution containing a polyurethane resin and a solvent, and a step of solidifying the polyurethane resin by immersing the polyurethane resin-containing solution in a coagulation liquid.
Including
The hardness component density | concentration which is the value which converted the density | concentration of calcium and magnesium derived from the calcium salt and magnesium salt contained in the said coagulation liquid into the density | concentration of the calcium carbonate of the same mole is 60.0 mg / L or less. The manufacturing method of the polishing pad of any one of these.   The manufacturing method of Claim 7 with which the said polyurethane resin containing solution contains anionic surfactant in the ratio of 0-15 mass parts with respect to 100 mass parts of polyurethane resins.   The said polyurethane resin containing solution contains at least 1 filler selected from the group which consists of carbon black and a silica in the ratio of 0.1-30 mass parts with respect to 100 mass parts of polyurethane resins. The manufacturing method as described.