JP2017185560A - Polishing pad and production method and polishing method of polishing pad - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing pad having good compatibility with a polishing liquid, being excellent in a polishing rate and capable of preventing the occurrence of clogging and scratch when polishing and to provide a production method and a polishing method of the polishing pad.SOLUTION: In a polishing pad having nonwoven fabric, a first resin and a second resin different from the first resin: the second resin is a reactant of an urethane prepolymer having an NCO equivalent of 500 or less, a bifunctional or more polyalkylene ether glycol having an OH equivalent of 500-10,000 and a curing agent; and a molar ratio of the amount of an OH group in the polyalkylene ether glycol to the amount of an NCO group in the urethane prepolymer is 0.01-0.15.SELECTED DRAWING: None

Description

  The present invention relates to a polishing pad, a method for manufacturing a polishing pad, and a polishing method.

  Since the surface of a semiconductor material such as a silicon wafer or SiC wafer is required to be flat, chemical mechanical polishing (CMP) using a polishing pad is performed.

  In CMP, a polishing pad in which a nonwoven fabric is impregnated with a polyurethane resin may be used, and various techniques for improving the hardness of the polishing pad have been proposed for the purpose of improving flatness. For example, in Patent Document 1, the hardness of the resulting polishing pad is improved by impregnating a polyurethane resin into a nonwoven fabric, wet coagulating the resin in a coagulation bath, treating the foam with a solvent, and further curing with a curing agent. It is described to do. In addition, a polishing pad in which a nonwoven fabric is impregnated with a resin a plurality of times in order to improve the hardness of the polishing pad and a method for manufacturing the same are also known (see, for example, Patent Documents 2 and 3).

Japanese Patent Laying-Open No. 2005-212055 Japanese Patent Publication No. 7-4769 Japanese Patent Laying-Open No. 2005-330621

  According to the techniques described in Patent Documents 1 to 3, the hardness can be increased, but the familiarity with the polishing liquid is poor and sufficient polishing efficiency (polishing rate) cannot be ensured. In particular, in the technique of Patent Document 1, hydrophilic groups such as OH groups contained in the wet-impregnated resin react with the composition of the curing agent that is then impregnated, resulting in insufficient hydrophilicity, resulting in a polishing rate. It becomes insufficient.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a polishing pad that has an excellent polishing rate and can prevent clogging and scratching during polishing, a method for manufacturing the polishing pad, and a polishing method. To do.

  As a result of intensive studies, the present inventors have found that a polishing pad having a specific configuration can solve the above problems, and have completed the present invention.

That is, this invention includes the following aspects.
[1]
A polishing pad having a nonwoven fabric, a first resin, and a second resin different from the first resin,
The second resin is a reaction product of a urethane prepolymer having an NCO equivalent of 500 or less, a polyalkylene ether glycol having a bifunctional or higher functionality and an OH equivalent of 500 to 10,000, and a curing agent,
A polishing pad, wherein the molar ratio of the amount of OH groups in the polyalkylene ether glycol to the amount of NCO groups in the urethane prepolymer is 0.01 to 0.15.
[2]
The ratio of the tensile strength of the polishing pad after immersing the polishing pad at 25 ° C. for 48 hours in a solution adjusted to pH 2 by adding nitric acid to a 3 mass% potassium permanganate aqueous solution to the tensile strength of the polishing pad is 45% or more of the polishing pad according to [1].
[3]
The content of the nonwoven fabric is 10 to 50% by mass, and the content of the first resin is 10 to 60% by mass with respect to the total of the nonwoven fabric, the first resin, and the second resin. The polishing pad according to [1] or [2], wherein the content of the second resin is 10 to 70% by mass.
[4]
The total molar ratio of the amount of OH groups in the polyalkylene ether glycol and the amount of NH ₂ groups in the curing agent to the amount of NCO groups in the urethane prepolymer is 0.8 to 1.0, [1] The polishing pad according to any one of to [3].
[5]
A primary impregnation step of obtaining a resin-impregnated nonwoven fabric by impregnating the nonwoven fabric with a resin solution containing the first resin and performing wet coagulation;
An immersion step of immersing the resin-impregnated nonwoven fabric in a solvent in which the first resin is soluble;
Secondary impregnating the resin-impregnated nonwoven fabric after the dipping step with a solution containing a urethane prepolymer having an NCO equivalent of 500 or less, a polyalkylene ether glycol having a bifunctional or higher functionality and an OH equivalent of 500 to 10,000, and a curing agent. An impregnation step;
Have
The manufacturing method of the polishing pad whose molar ratio of the quantity of OH group in the said polyalkylene ether glycol with respect to the quantity of NCO group in the said urethane prepolymer is 0.01-0.15.
[6]
The method for producing a polishing pad according to [5], wherein the first resin is soluble in one or more solvents selected from the group consisting of N, N-dimethylformamide, dimethylacetamide, and methyl ethyl ketone.
[7]
The method for producing a polishing pad according to [5] or [6], wherein the solvent contains one or more solvents selected from the group consisting of N, N-dimethylformamide, dimethylacetamide, and methyl ethyl ketone.
[8]
A polishing method in which a compound semiconductor wafer is polished with the polishing pad according to any one of [1] to [4] while being in contact with a solution containing potassium permanganate.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the polishing pad which is excellent in a polishing rate, can prevent clogging at the time of grinding | polishing, and generation | occurrence | production of a scratch, the manufacturing method of a polishing pad, and a polishing method.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. In addition, this embodiment is an illustration for demonstrating this invention, and this invention is not limited only to the following embodiment.

[Polishing pad]
The polishing pad of the present embodiment is a polishing pad having a nonwoven fabric, a first resin, and a second resin different from the first resin, and the second resin has an NCO equivalent of 500 or less. Urethanum prepolymer, a polyalkylene ether glycol having a bifunctional or higher functionality and an OH equivalent of 500 to 10,000, and a curing agent, and an OH group in the polyalkylene ether glycol with respect to the amount of NCO groups in the urethane prepolymer The molar ratio of the amount is 0.01 to 0.15. Because of such a configuration, the polishing pad of this embodiment has an excellent polishing rate and can prevent clogging and scratching during polishing.

(Nonwoven fabric)
The nonwoven fabric in this embodiment is not specifically limited, A various well-known thing is employable. Examples of the nonwoven fabric include polyamide-based and polyester-based nonwoven fabrics. Moreover, it is not specifically limited as a method of making a fiber entangle when obtaining a nonwoven fabric, For example, a needle punch may be sufficient and hydroentanglement may be sufficient. A nonwoven fabric can be used individually by 1 type from among the above-mentioned, and can also be used in combination of 2 or more type.

  Although the thickness of the nonwoven fabric in this embodiment is not specifically limited, From a viewpoint of polishing pad thickness, it is preferable that it is 2-5 mm.

  The fineness of the nonwoven fabric in this embodiment is not particularly limited, but is preferably 2 to 6d from the viewpoint of reducing the occurrence of scratches during polishing.

Although the fabric weight of the nonwoven fabric in this embodiment is not specifically limited, From a viewpoint of a polishing pad density or a ratio of a nonwoven fabric and resin, it is preferable that it is 200-1000 g / m < ² >.

(First resin)
The first resin in the present embodiment is not particularly limited as long as it can be impregnated into the nonwoven fabric by so-called wet impregnation, and various known ones can be applied. Examples of such a resin (hereinafter also simply referred to as “wet resin”) include, but are not limited to, polyurethanes such as polyurethane and polyurethane polyurea, acrylics such as polyacrylate and polyacrylonitrile, polyvinyl chloride, Examples thereof include vinyls such as polyvinyl acetate and polyvinylidene fluoride, polysulphones such as polysulfone and polyethersulphone, acylated celluloses such as acetylated cellulose and butyryl cellulose, polyamides and polystyrenes. Examples of the polyurethane resin include, but are not limited to, a polyester-based polyurethane resin, a polyether-based polyurethane resin, and a polycarbonate-based polyurethane resin. The 100% modulus of the resin is preferably 5 MPa to 30 MPa, and more preferably 10 MPa to 20 MPa. The 100% modulus of the resin is a value obtained by dividing the load applied by the unit area when the sheet made of the resin is stretched 100%, that is, when the sheet is stretched twice the original length.

(Second resin)
The second resin in the present embodiment is a reaction product of a urethane prepolymer having an NCO equivalent of 500 or less, a polyalkylene ether glycol having a bifunctional or higher functionality and an OH equivalent of 500 to 10,000, and a curing agent, so-called dry impregnation. Thus, the nonwoven fabric can be impregnated. That is, the second resin (hereinafter, also simply referred to as “dry resin”) includes, for example, a urethane prepolymer having an isocyanate group at a terminal, a polyalkylene ether glycol, an amine compound as a curing agent, and / or a polyvalent resin. It can be obtained by a dry method using a solution containing an alcohol compound and a solvent capable of dissolving them.

  Examples of the urethane prepolymer having an NCO equivalent of 500 or less include, but are not limited to, an adduct of hexamethylene diisocyanate and hexanetriol, an adduct of 2,4-tolylene diisocyanate and prenzcatechol, and tolylene diisocyanate. Adducts with hexanetriol, adducts of tolylene diisocyanate and trimethylolpropane, adducts of xylylene diisocyanate and trimethylolpropane, adducts of hexamethylene diisocyanate and trimethylolpropane, and isocyanuric acid and hexamethylene diisocyanate And adducts.

  The polyalkylene ether glycol having a bifunctional or higher functionality and an OH equivalent of 500 to 10000 is not limited to the following, but examples thereof include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, and glycerol, sorbitol and mannitol. And other polyhydric alcohol derivatives.

  Among the curing agents, examples of the amine compound include a polyfunctional polyamine compound. Examples of the polyfunctional polyamine compound include, but are not limited to, 3,3′-dichloro-4,4′-diaminodiphenylmethane, 4-methyl-2,6-bis (methylthio) -1,3-benzenediamine, 2-methyl-4,6-bis (methylthio) -1,3-benzenediamine, 2,2-bis (3-amino-4-hydroxyphenyl) propane, 2,2-bis [3- (isopropylamino)- 4-hydroxyphenyl] propane, 2,2-bis [3- (1-methylpropylamino) -4-hydroxyphenyl] propane, 2,2-bis [3- (1-methylpentylamino) -4-hydroxyphenyl ] Propane, 2,2-bis (3,5-diamino-4-hydroxyphenyl) propane, 2,6-diamino-4-methylphenol, trimethyl Chirenbisu 4- aminobenzoyl sulfonates, and polytetramethylene oxide -di-p-aminobenzoyl titanate and the like. Examples of the polyhydric alcohol compound include, but are not limited to, ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3- Butanediol, 2,3-butanediol, 1,2-butanediol, 3-methyl-1,2-butanediol, 1,2-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2 , 3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-4,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 1 , 6-hexanediol, 1,5-hexane Ol, 1,4-hexanediol, 2,5-hexanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, glycerol, trimethylol propane, trimethylol ethane, trimethylol methane. Among the above, a polyfunctional polyamine compound is preferably used as a curing agent, and more preferably a bifunctional amine compound.

  The above-mentioned urethane prepolymer, polyalkylene ether glycol and curing agent are used singly or in combination of two or more. The solvent is not particularly limited, and examples thereof include N, N-dimethylformamide and N, N-dimethylacetamide.

  In this embodiment, the NCO equivalent of the urethane prepolymer is 500 or less from the viewpoint of imparting good chemical resistance to the polishing pad. From the same viewpoint, the NCO equivalent is preferably 450 or less, and more preferably 200 or more. In the present specification, “NCO equivalent” means the average NCO equivalent of the urethane prepolymer in the resin solution. Further, the NCO equivalent can be measured by a well-known method, for example, it can be measured according to JIS K 7301. The NCO equivalent can be adjusted to the above-described range depending on, for example, the raw material and the blending ratio thereof.

  In this embodiment, from the viewpoint of improving the affinity of the polishing pad for the polishing liquid, the polyalkylene ether glycol is bifunctional or higher, and the OH equivalent is 500 to 10,000. From the same viewpoint, the polyalkylene ether glycol is preferably trifunctional. Moreover, it is preferable that the OH equivalent of polyalkylene ether glycol is 500-3000, and it is more preferable that it is 500-2000. In the present specification, “OH equivalent” means the average OH equivalent of the polyalkylene ether glycol in the corresponding resin solution. The OH equivalent can be measured by a known method and can be controlled by, for example, the degree of polymerization of polyalkylene ether glycol.

In this embodiment, the molar ratio of the amount of OH groups in the polyalkylene ether glycol to the amount of NCO groups in the urethane prepolymer is 0.01 to 0.15. When the molar ratio is 0.01 or more, the amount of OH groups on the surface of the dry resin is sufficiently secured, so that the affinity of the polishing pad for the polishing liquid is improved. Moreover, when the molar ratio is 0.15 or less, it is possible to prevent a decrease in the adhesion of the polishing pad to the polishing surface plate of the polishing machine due to an excessive amount of OH groups on the surface of the dry resin. Can do. From the same viewpoint as described above, the molar ratio is preferably 0.02 to 0.12, and more preferably 0.03 to 0.10.
The molar ratio can be determined by calculation from OH equivalents and NCO equivalents obtained by the methods described in Examples described later, and can be adjusted to the above-described range by the respective equivalents and blending ratios.

In this embodiment, from the viewpoint of the balance between the affinity of the polishing pad for the polishing liquid and the adhesion of the polishing pad to the polishing surface plate of the polishing machine, the amount of OH groups in the polyalkylene ether glycol relative to the amount of NCO groups in the urethane prepolymer The total molar ratio of the amount and the amount of NH ₂ groups in the curing agent is preferably 0.8 to 1.0.
The molar ratio can be determined by calculation from the OH equivalent, NCO equivalent, and NH ₂ equivalent obtained by the method described in Examples described later, and can be adjusted to the above-described range by the respective equivalents and blending ratios. .

  In the polishing pad of this embodiment, from the viewpoint of maintaining the tensile strength during polishing, the content of the nonwoven fabric is 10 to 50% by mass with respect to the total of the nonwoven fabric, the first resin, and the second resin, and It is preferable that the content of the first resin is 10 to 60% by mass and the content of the second resin is 10 to 70% by mass. From the same viewpoint, the content of the nonwoven fabric is 20 to 40% by mass, the content of the first resin is 20 to 60% by mass, and the content of the second resin is 20 to 50% by mass. % Is more preferable. Each content of the nonwoven fabric, the first resin, and the second resin in the polishing pad is determined by using the difference in solubility (polarity) in a polar solvent or the difference in amine decomposability, and the mass or residue of the eluted component. From the mass of Further, the density of the polishing pad after the primary impregnation step described later, the density of the polishing pad after the immersion step described later, and the density of the polishing pad after the secondary impregnation step described later are measured, respectively, from the difference in density. It can also be calculated. The density can be measured in the same manner as described above.

  The polishing pad of the present embodiment may contain various additives that can be included in a normal polishing pad as long as the desired effects of the present embodiment are not impaired in addition to the above-described nonwoven fabric and resin. Such additives include, but are not limited to, pigments such as carbon black, hydrophilic activators and hydrophobic activators.

  In the present embodiment, the polishing pad is placed at 25 ° C. in a solution adjusted to pH 2 by adding nitric acid to a 3 mass% potassium permanganate aqueous solution with respect to the tensile strength of the polishing pad (hereinafter also referred to simply as “test solution”). The ratio of the tensile strength of the polishing pad after immersion for 48 hours (hereinafter also simply referred to as “tensile strength retention”) is preferably 45% or more. When satisfying such a tensile strength retention rate, the polishing pad of this embodiment tends to be more excellent in chemical resistance, and a sufficiently long life is ensured even when subjected to polishing using a strong oxidizing agent. There is a tendency.

A method for measuring the tensile strength retention in the present embodiment will be described. First, the tensile strength (a) of the polishing pad before being immersed in the test solution is measured. The tensile strength can be measured using a tensile universal testing machine (“Tensilon”, manufactured by A & D, RTC-1210A) in accordance with Japanese Industrial Standard (JIS K 6550). Next, nitric acid is added to a 3% by mass aqueous potassium permanganate solution to adjust the pH to 2 to obtain a test solution. The polishing pad is immersed in the test solution thus prepared at 25 ° C. for 48 hours. The container containing the test solution and the polishing pad is shaken for several minutes after the elapse of 24 hours from the start of immersion. After 48 hours from the start of immersion, the polishing pad is removed from the test solution, washed with running water, subjected to ultrasonic washing for 5 minutes, washed with running water, and the remaining solution is wiped off while pressing with kitchen paper. Then, the tensile strength (b) of the polishing pad is measured. The tensile strength retention is calculated by the following formula from the values of tensile strength (a) and tensile strength (b).
Tensile strength retention rate = tensile strength (b) / tensile strength (a) × 100%

  In the present embodiment, from the viewpoint of chemical resistance, the tensile strength retention is preferably 45% or more, more preferably 50% or more. In order to adjust the tensile strength retention within the above range, for example, a preferable manufacturing method described later may be employed. In a preferable production method described later, for example, the tensile strength retention tends to be increased by lowering the NCO equivalent of the second resin.

Air permeability of the polishing pad, from the viewpoint of retention of the polishing liquid, preferable to be 6 cc / cm ² / sec or more, and more preferably 7~30cc / cm ² / sec. The air permeability is measured according to the Japanese Industrial Standard (JIS L 1096) using a Frazier type tester (for example, a woven fabric air permeability tester manufactured by Yasuda Seiki Co., Ltd.), and the additive of five specimens is added. Obtained by average. For example, the air permeability tends to increase by adopting an immersion step in which the first resin is immersed in a soluble solvent between the primary impregnation step and the secondary impregnation step in a preferable manufacturing method described later. .

The compression rate of the polishing pad is 0.5 to 20% from the viewpoint of ensuring good adhesion to the object to be polished (hereinafter also simply referred to as “work”) and from the viewpoint of preventing deformation of the polishing pad. Preferably, it is more preferable in it being 2 to 8%. The compression rate is determined using a shopper type thickness measuring instrument (pressure surface: circle with a diameter of 1 cm) in accordance with Japanese Industrial Standards (JIS L 1021). Specifically, the thickness t ₀ after pressing for 30 seconds with an initial load is measured, and then the thickness t ₁ after standing for 5 minutes under the final pressure is measured. From these, the compression rate is calculated by the following equation. At this time, the initial load is 100 g / cm ² and the final load is 1120 g / cm ² .
Compression rate (%) = (t ₀ −t ₁ ) / t ₀ × 100
For example, in a preferable manufacturing method described later, the compression rate tends to be increased by adjusting the density of the obtained polishing pad to be low.

The compression elastic modulus of the polishing pad is preferably 50 to 98% and more preferably 60 to 95% from the viewpoint of securing good adhesion to the work and the prevention of deformation of the polishing pad. The compressive elastic modulus can be determined using a shopper type thickness measuring instrument (pressurized surface: circular with a diameter of 1 cm) in accordance with Japanese Industrial Standard (JIS L 1021). Specifically, the thickness t ₀ after over 30 seconds initial load from a no-load state is measured, then the thickness t ₁ after applying a final load 30 seconds from the state of the thickness t ₀ taking measurement. 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. From these, the compression modulus is calculated by the following formula. At this time, the initial load is 100 g / cm ² and the final load is 1120 g / cm ² .
Compression elastic modulus (%) = 100 × (t ₀ ′ −t ₁ ) / (t ₀ −t ₁ )
For example, in a preferable manufacturing method described later, the compression elastic modulus tends to be increased by increasing the content of the second resin.

  The A hardness of the polishing pad is not particularly limited, but is preferably 50 to 90 ° and more preferably 60 to 85 ° from the viewpoint of ensuring good adhesion to the workpiece and the prevention of deformation of the polishing pad. preferable. A hardness is a test piece having a thickness of 4.5 mm or more via a spring (if the polishing pad has a thickness of less than 4.5 mm, the polishing pad is stacked until the thickness becomes 4.5 mm or more. This is obtained from the pushing depth of the push needle 30 seconds after pressing the push needle (measuring element) on the surface. This is performed three times to obtain the A hardness from the arithmetic mean. The A hardness tends to increase, for example, by increasing the content of the second resin in a preferable manufacturing method described later.

The density of the polishing pad is 0.35 to 0 from the viewpoint of suppressing permanent deformation of the polishing pad, suppressing the pressure drop at the action point due to the increase in the contact area with the workpiece, and improving the retention of the polishing liquid. .60 is preferable, and 0.35 to 0.50 is more preferable. The density is measured in accordance with Japanese Industrial Standard (JIS K 6505). Specifically, after measuring the mass of the sample piece similar to that used in the thickness measurement with an automatic balance, the density is calculated by the following formula, and the arithmetic average of the three sample pieces is obtained.
Density (g / cm ³ ) = mass (g) / (10 (cm) × 10 (cm) × sample piece thickness (cm))
For example, the density tends to be increased by increasing the contents of the first resin and the second resin with respect to the nonwoven fabric in a preferable manufacturing method described later.

The thickness of the polishing pad of the present embodiment is not particularly limited, but from the viewpoint of sufficiently securing a flat contact surface with the workpiece, from the viewpoint of ensuring flatness and from the viewpoint of storing a polishing liquid, 0.8 to 3 0.0 mm is preferable, and 1.0 to 1.8 mm is more preferable. The thickness is measured in accordance with Japanese Industrial Standard (JIS K 6505). Specifically, three sample pieces obtained by cutting a polishing pad into 10 cm × 10 cm squares were prepared, and each sample piece was set at a predetermined position of a thickness measuring instrument, and then a load of 480 g / cm ² was applied. The applied pressure surface is placed on the surface of the sample piece, and the thickness is measured after 5 seconds. For each sample piece, the thickness is measured at five locations to calculate an arithmetic average, and an arithmetic average of three sample pieces is obtained.

[Production method of polishing pad]
The manufacturing method of the polishing pad of this embodiment is not particularly limited as long as it is a method by which the configuration of the polishing pad of this embodiment described above can be obtained. Hereinafter, a preferred method for producing the polishing pad of this embodiment will be exemplified.

  The manufacturing method of the polishing pad of this embodiment includes a primary impregnation step of impregnating a nonwoven fabric with a resin solution containing a first resin and performing wet coagulation to obtain a resin-impregnated nonwoven fabric; An immersion step in which the resin is immersed in a soluble solvent, a resin-impregnated nonwoven fabric after the immersion step, a urethane prepolymer having an NCO equivalent of 500 or less, a polyalkylene ether glycol having a bifunctional or higher functionality and an OH equivalent of 500 to 10,000 A secondary impregnation step of impregnating a solution containing a curing agent, and the molar ratio of the amount of OH groups in the polyalkylene ether glycol to the amount of NCO groups in the urethane prepolymer is 0.01 to 0.15 is there. Since the manufacturing method of the polishing pad according to this embodiment is configured as described above, a polishing pad that has an excellent polishing rate and can prevent clogging and scratching during polishing can be obtained. Furthermore, the polishing pad thus obtained has excellent chemical resistance and can ensure a sufficient life even when it is subjected to polishing using a strong oxidizing agent.

  In the primary impregnation step, a resin-impregnated nonwoven fabric is obtained by wet coagulation after impregnating the nonwoven fabric with a resin solution. The wet coagulation method is a method in which a resin solution is coagulated and regenerated by immersing the resin solution in a coagulation liquid that is a poor solvent for the resin at room temperature. When the wet coagulation method is used after impregnating the nonwoven fabric with the resin solution as in the present embodiment, in the coagulation liquid, the solvent of the resin solution and the coagulation liquid are adhered to the surface of the resin solution adhering to the fibers of the nonwoven fabric. As the substitution proceeds, the resin is coagulated and regenerated on the fiber surface.

  Specific examples of the primary impregnation step are as follows. First, the wet resin as described above, the solvent capable of dissolving the wet resin, mixed with the coagulating liquid described later, and other additives blended into the polishing pad as necessary are mixed, and further necessary And degassing under reduced pressure to prepare a resin solution. The solvent is not particularly limited, and examples thereof include N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAC), methyl ethyl ketone (MEK), and dimethyl sulfoxide. The group in which the first resin is composed of N, N-dimethylformamide, dimethylacetamide, and methyl ethyl ketone from the viewpoint of selecting a good solvent for the resin, and from the viewpoint of facilitating wet coagulation by mixing uniformly with the coagulation bath. It is preferably soluble in one or more kinds of solvents selected from the above. Similarly, the solvent preferably contains one or more solvents selected from the group consisting of N, N-dimethylformamide, dimethylacetamide and methyl ethyl ketone.

  From the viewpoint of impregnating the resin throughout the entire nonwoven fabric and from the viewpoint of sufficiently ensuring the impregnation amount of the resin, the viscosity of the resin solution measured at 20 ° C. using a B-type rotational viscometer is 8000 cp or less. And preferably 100 cp to 5000 cp, more preferably 400 cp to 3000 cp. From the viewpoint of obtaining a resin solution having such a numerical value range of viscosity, for example, the polyurethane resin is a solvent in a range of 5 to 25% by mass, more preferably in a range of 8 to 15% by mass with respect to the total amount of the resin solution. It may be dissolved in Since the viscosity of the resin solution also depends on the type and molecular weight of the resin to be used, it is preferable to select the resin, set the concentration, etc. in consideration of these comprehensively.

  Next, after sufficiently immersing the nonwoven fabric in the resin solution, the resin solution is squeezed out from the nonwoven fabric to which the resin solution is adhered using a mangle roller that can be pressurized between a pair of rollers, thereby forming the resin solution nonwoven fabric. Is adjusted to a desired amount, and the nonwoven fabric is impregnated with the resin solution uniformly or substantially uniformly. Next, the wet resin is coagulated and regenerated by immersing the nonwoven fabric impregnated with the resin solution in a coagulating liquid containing a poor solvent for the resin, for example, water as a main component. In order to adjust the regeneration speed of the resin, an organic solvent such as a polar solvent other than the solvent in the resin solution may be added to the coagulation liquid. The temperature of the coagulation liquid is not particularly limited as long as the resin can be coagulated, and may be, for example, 15 to 60 ° C.

  In this embodiment, after performing the above-mentioned wet coagulation, it is preferable to use the following washing / drying steps. First, the nonwoven fabric obtained by coagulating and regenerating the wet resin is washed in a cleaning solution such as water, and the solvent such as DMF remaining in the nonwoven fabric is removed. After cleaning, the nonwoven fabric is pulled up from the cleaning solution, and excess cleaning solution is squeezed out using a mangle roller or the like. Then, you may dry a nonwoven fabric base material in a 100 to 150 degreeC dryer. In addition, after the drying, the obtained resin-impregnated nonwoven fabric is further subjected to processing by slicing, buffing, etc., and the skin layer of the surface layer is removed to give a predetermined thickness, which improves the uniformity of the dipping process of the next process It is preferable from the viewpoint.

  The dipping process in the present embodiment is a process of re-dissolving the wet resin in the solvent by immersing the resin-impregnated nonwoven fabric in a solvent in which the wet resin is soluble. It is thought that by the dipping process, bubbles inside the resin-impregnated nonwoven fabric (for example, closed pores and open pores having small openings) are reduced, and adhesion between the nonwoven fabric and the wet resin is improved. Although it does not specifically limit as a solvent used for an immersion process, For example, N, N- dimethylformamide (DMF), N, N- dimethylacetamide (DMAC), methyl ethyl ketone (MEK), and dimethyl sulfoxide are mentioned. Moreover, as temperature conditions at the time of immersion, it is preferable that it is 15.0-25.0 degreeC from a viewpoint of reducing the bubble of 1st resin and preventing the elution of the resin to a solvent, The time is preferably 5 to 30 seconds from the same viewpoint. In addition, it is preferable to provide a drying process after the above-mentioned immersion process.

  In the secondary impregnation step in this embodiment, the resin-impregnated non-woven fabric after the dipping step is obtained by adding a urethane prepolymer having an NCO equivalent of 500 or less, a polyalkylene ether glycol having a bifunctional or higher functionality and an OH equivalent of 500 to 10,000, and a curing agent. Impregnation in a solution containing It is estimated that a dry resin is formed on the surface of the wet resin described above by the secondary impregnation step.

  As a specific example of the secondary impregnation step, first, a urethane prepolymer having an isocyanate group at the terminal, which has an NCO equivalent of 500 or less, a polyalkylene ether glycol having a bifunctional or higher and an OH equivalent of 500 to 10,000, A solution containing a curing agent (for example, a polyfunctional polyamine compound and / or a polyhydric alcohol compound) and a solvent capable of dissolving them is prepared. Here, from the viewpoint described above, the molar ratio of the amount of OH groups in the polyalkylene ether glycol to the amount of NCO groups in the urethane prepolymer is adjusted to be 0.01 to 0.15. In addition, the thing similar to what was illustrated above can be used for a urethane prepolymer, polyalkylene ether glycol, a hardening | curing agent (for example, polyfunctional polyamine compound and / or polyhydric alcohol compound), and a solvent. In addition, these urethane prepolymers and curing agents are used singly or in combination of two or more.

  Next, after immersing the resin-impregnated nonwoven fabric after the immersion step in the solution, from the resin-impregnated nonwoven fabric to which the solution is adhered, the solution is squeezed out using a mangle roller that can be pressurized between a pair of rollers, The adhesion amount of the solution to the resin-impregnated nonwoven fabric is adjusted to a desired amount, and the resin-impregnated nonwoven fabric is impregnated with the solution uniformly or substantially uniformly. Next, the resin-impregnated nonwoven fabric impregnated with the solution is dried in a dryer. As a result, the polishing pad of the present embodiment obtained by polymerizing with the urethane prepolymer and the curing agent and impregnating the resin-impregnated nonwoven fabric with the dry resin is obtained. As a drying temperature, 100 to 140 degreeC may be sufficient, for example.

By passing through the primary impregnation process, the immersion process, and the secondary impregnation process described above, a polishing pad having the desired configuration of this embodiment can be obtained. This polishing pad is not intended to be limited to the contents described below, but is presumed to have the following configuration. That is, a wet resin is formed on the surface of the nonwoven fabric through the primary impregnation step. In particular, by adopting wet coagulation in the primary impregnation step, the wet resin adheres uniformly within the nonwoven fabric. However, at this stage, there are many fine bubbles derived from the wet coagulation method inside the resin-impregnated nonwoven fabric obtained, and the adhesion and strength between the nonwoven fabric and the wet resin are not sufficient. Then, the immersion solution is filled into the fine bubbles of the wet resin by passing through an immersion step, and the wet resin is preferably re-dissolved by heating during drying, and fine bubbles (for example, closed pores and The number of open pores) is reduced, and the resin impregnated in the nonwoven fabric (wet resin) is densified around the fibers, improving the adhesion between the nonwoven fabric fibers and the wet resin and improving the strength. To do. Further, the reduction of fine bubbles leads to uniform impregnation of dry resin and improvement of strength in the secondary impregnation step. Furthermore, a dry resin layer is further formed on the surface of the wet resin layer on the nonwoven fabric fiber through the secondary impregnation step. If the process proceeds to the secondary impregnation step without going through the dipping step, it becomes difficult for the dry resin to penetrate into the spaces in the bubbles inside the resin-impregnated nonwoven fabric, and the adhesion of the dry resin becomes uneven. In this case, the wet resin and the dry resin are in a non-uniform state, and the elastic properties and rigidity properties are partially non-uniform so that the resin in the polishing pad is peeled off during polishing, shortening the service life. End up. In addition, since the strong oxidant easily enters into the bubbles where there is no dry resin excellent in resistance to the strong oxidant, the chemical resistance is inferior and the life is shortened. On the other hand, according to the present embodiment, since air bubbles are reduced in the dipping process, voids that can be impregnated in the secondary impregnation process are secured and air permeability is improved. The area where the resin is present increases. Therefore, the strong oxidant is prevented from entering a region where no dry resin is present, the chemical resistance is improved, and the life can be extended. Moreover, since the wet resin of the part which is not directly attached to a nonwoven fabric reduces, peeling of the resin in a polishing pad is suppressed in the case of grinding | polishing, and lifetime can be lengthened. Furthermore, since the dry resin layer is formed using a urethane prepolymer having a specific NCO equivalent, good chemical resistance is imparted. Here, since the dry resin has poor moisture retention compared to the wet resin, it is difficult to sufficiently hold the polishing liquid with the conventional dry resin alone. However, the dry resin layer in this embodiment has the urethane resin layer. Since it is formed using polyalkylene ether glycol in addition to the polymer, the amount of OH groups on the surface is adjusted to the desired range, maintaining the adhesion to the polishing pad while maintaining the affinity for the polishing liquid. Can be improved. As a result of the improved affinity between the polishing pad and the polishing liquid, the circulation of the polishing liquid is improved, the rise time (the time from the supply of the polishing liquid to the start of polishing) is shortened, and the polishing rate is improved. Furthermore, clogging due to silica in the polishing liquid during polishing and generation of scratches on the object to be polished can be prevented.
As described above, in the polishing pad of this embodiment, it is assumed that a nonwoven fabric is used as a base material, a wet resin layer is formed on the nonwoven fabric, and a dry resin layer is formed on the wet resin layer. In addition, as a whole of the polishing pad, it is presumed that the adhesion between the nonwoven fabric and the wet resin layer and the adhesion between the wet resin layer and the dry resin layer are all good. From the above viewpoint, it is considered that the polishing pad of this embodiment is excellent in chemical resistance and can ensure a sufficient life even when subjected to polishing using a strong oxidizing agent.
In addition, when the primary impregnation step and the immersion step are omitted and the nonwoven fabric is impregnated with the dry resin by the secondary impregnation step, the familiarity between the nonwoven fabric and the dry resin is poor, and a problem occurs in the adhesion between the fiber and the resin. This will impair the stability. Moreover, when only dry resin is made to adhere to a nonwoven fabric and wet resin is not made to adhere, it becomes high hardness and low elasticity as a polishing pad, the follow-up property with respect to the to-be-polished object is bad, and troubles are carried out.

  The fact that the polishing pad of the present embodiment has the configuration inferred as described above is not limited to the following, but for example, not only the value of the tensile strength retention rate of the polishing pad but also the above-described air permeability. It can be confirmed from the values and values of the contents of the nonwoven fabric, the first resin and the second resin in the polishing pad.

  The polishing pad obtained as described above may then be cut into a desired shape and size such as a circle as necessary, and inspection such as confirming that there is no dirt or foreign matter attached. May be applied.

  The obtained polishing pad has a polishing surface. When the workpiece is polished using the polishing pad, the surface of the polishing pad opposite to the polishing surface is previously placed on the polishing surface plate of the polishing machine. A double-sided tape (with an adhesive layer and release paper) for attaching the polishing pad may be attached.

[Polishing method]
The polishing method of the present embodiment is not particularly limited as long as polishing is performed using the polishing pad of the present embodiment, but the compound semiconductor wafer is brought into contact with a solution containing potassium permanganate while the polishing method of the present embodiment is used. It can have the process of grind | polishing with a polishing pad. A specific example will be described. First, a work is held on a holding surface plate of a single-side polishing machine. Next, the polishing pad is mounted on the polishing surface plate disposed so as to face the holding surface plate. When the polishing pad is attached to the polishing surface plate, the release paper is peeled from the double-sided tape to expose the adhesive layer, and then the exposed adhesive layer is brought into contact with the polishing surface plate and pressed. And while circulatingly supplying the solution (polishing liquid) which contains potassium permanganate and an abrasive grain as needed between a workpiece | work and a polishing pad, pressing a workpiece | work toward a polishing pad with a predetermined polishing pressure The workpiece is polished by chemical mechanical polishing by rotating the polishing platen or holding platen. At this time, by using the polishing pad of the present embodiment, it is possible to ensure a sufficiently high flatness of the object to be polished together with a high polishing rate and a long polishing pad life. In the polishing method of this embodiment, a strong oxidizing agent such as sodium permanganate may be used in addition to or instead of potassium permanganate.

[Use of polishing pad]
The polishing pad according to the present embodiment is used for polishing optical materials such as lenses, plane-parallel plates, reflection mirrors, hard disk substrates, semiconductor silicon wafers, glass substrates for liquid crystal displays, difficult-to-cut materials such as sapphire and gallium nitride. Is particularly preferably used. However, the use of the polishing pad of this embodiment is not limited to them.

  Hereinafter, the present embodiment will be described in more detail by way of examples. However, the present embodiment is not limited to these examples.

[Raw materials]
Resin for primary impregnation used in Examples and Comparative Examples (primary impregnation resin), cross-linking agent for primary impregnation (primary cross-linking agent), solvent for primary impregnation (primary impregnation solvent), for dipping process As the solvent (immersion solvent), secondary impregnation resin (secondary impregnation resin), polyalkylene ether glycol, and secondary impregnation curing agent (secondary curing agent), the following were used. These are summarized in Table 1. The details of the secondary impregnation resin, polyalkylene ether glycol and secondary curing agent are shown in Table 2.

(Primary impregnating resin)
UW-1: Ester-based urethane resin (manufactured by DIC, trade name “Chrisbon UW-1”)
(Primary crosslinking agent)
DN-950: Urethane prepolymer (manufactured by DIC, trade name “Bernock DN950”)
(Primary impregnation solvent)
N, N-dimethylformamide (DMF)
(Immersion solvent)
DMF / water (mass ratio 65/35)
(Secondary impregnation resin)
UP121: Urethane prepolymer (Mitsubishi Resin Co., Ltd., trade name “Novaretan UP121”, NCO equivalent 440)
DC6912: Urethane prepolymer (trade name “DC6912”, NCO equivalent 540, manufactured by Tosoh Corporation)
In addition, said NCO equivalent was measured based on JISK7301.
(Polyalkylene ether glycol)
TG-3000: Polyoxypropylene glycol (manufactured by DIC, trade name “Hyprox TG-3000”, OH equivalent 1007)
In addition, said OH equivalent was measured based on JISK0070.
(Secondary curing agent)
E (MOCA): Curing agent (manufactured by DIC, trade name “Pandex E”, NH ₂ equivalent: 133.58)
The above NH ₂ equivalent weight was measured conforming to JIS K7237.

[Examples 1-4, Comparative Examples 1-3]
(Primary impregnation step)
In the resin solution prepared by mixing the above-mentioned primary impregnation resin, primary cross-linking agent, and primary impregnation solvent with the composition shown in Table 1, the fiber material is PET, the thickness is 3.5 mm, and the basis weight is 620 g. A non-woven fabric (fineness 3d) of / m ² was dipped. After dipping, the resin solution was squeezed out using a mangle roller capable of pressurizing between a pair of rollers, and the nonwoven fabric was impregnated with the resin solution substantially uniformly. Subsequently, the primary impregnation resin was solidified and regenerated by immersing it in a coagulation liquid composed of room temperature water to obtain a resin-impregnated nonwoven fabric. Thereafter, the resin-impregnated non-woven fabric was taken out of the coagulation liquid and further immersed in a cleaning liquid consisting of water to remove DMF and then dried. After drying, a resin-impregnated nonwoven fabric from which the surface skin layer was removed by buffing was obtained.
(Immersion process)
Next, the resin-impregnated nonwoven fabric obtained above was immersed in an immersion solvent in which DMF and pure water were mixed at a ratio of 65 to 35. Then, washing | cleaning and drying were performed and the resin impregnation nonwoven fabric after the immersion process was obtained.
(Secondary impregnation step)
Furthermore, the resin-impregnated non-woven fabric after the dipping process was dipped in a solution prepared by blending the secondary impregnating resin, polyalkylene ether glycol and secondary curing agent shown in Table 2. Then, washing | cleaning and drying were performed and the polishing pad of Examples 1-4 and Comparative Examples 1-3 was obtained.

[Evaluation of the physical properties]
About the polishing pad of each Example and comparative example obtained as mentioned above, the physical property was measured as follows and quality was evaluated. The results are shown in Table 2.

(thickness)
Based on Japanese Industrial Standard (JIS K 6505), the thickness of the polishing pad was measured as follows. First, three sample pieces obtained by cutting a polishing pad into 10 cm × 10 cm squares were prepared, and each sample piece was set at a predetermined position of a thickness measuring instrument. Thereafter, a pressure surface to which a load of 480 g / cm ² was applied was placed on the surface of the sample piece, and the thickness was measured after 5 seconds. At that time, the thickness of five locations was measured for one sample piece, the arithmetic average was calculated, and the arithmetic average of three sample pieces was further obtained to obtain the thickness of the polishing pad.

(density)
In accordance with Japanese Industrial Standard (JIS K 6505), the density of the polishing pad was measured as follows. That is, a sample piece similar to that used in the thickness measurement was prepared, the mass was measured with an automatic balance, the density was calculated by the following formula, and the arithmetic average of the three sample pieces was obtained to obtain a polishing pad Density.
Density (g / cm ³ ) = mass (g) / (10 (cm) × 10 (cm) × sample piece thickness (cm))

(Nonwoven fabric, wet resin and dry resin content)
The contents of the nonwoven fabric, wet resin and dry resin in the polishing pad are the density of the polishing pad after the primary impregnation step, the density of the polishing pad after the immersion step, and the density of the polishing pad after the secondary impregnation step. And were calculated from the difference in density. The density was measured in the same manner as the above (density).

(Air permeability)
The air permeability of the polishing pad was measured in accordance with Japanese Industrial Standard (JIS L 1096) using a fragile type tester (woven fabric air permeability tester manufactured by Yasuda Seiki Co., Ltd.). The arithmetic average of the five sample pieces was defined as the air permeability of the polishing pad.

(Compression rate)
The compressibility of the polishing pad was measured as follows using a shopper type thickness measuring instrument (pressurized surface: circular with a diameter of 1 cm) in accordance with Japanese Industrial Standard (JIS L 1021). That is, measuring the thickness t ₀ after pressurized for 30 seconds at initial load, and then measuring the thickness t ₁ after standing under a final pressure of 5 minutes. From these, the compression rate was calculated by the following equation. At this time, the initial load was 100 g / cm ² and the final load was 1120 g / cm ² .
Compression rate (%) = (t ₀ −t ₁ ) / t ₀ × 100

(Compressive modulus)
Using a shopper type thickness measuring instrument (pressurized surface: circular with a diameter of 1 cm), the compressive elastic modulus of the polishing pad was measured as follows in accordance with Japanese Industrial Standard (JIS L 1021). That is, the thickness t ₀ after the initial load was applied for 30 seconds from the no-load state was measured, and then the thickness t ₁ after the final load was applied for 30 seconds from the thickness t ₀ state was measured. Next, all loads were removed from the state of thickness t ₁ , and after standing for 5 minutes (no load state), thickness t ₀ ′ after applying the initial load for 30 seconds again was measured. From these, the compression modulus was calculated by the following formula. At this time, the initial load was 100 g / cm ² and the final load was 1120 g / cm ² .
Compression elastic modulus (%) = 100 × (t ₀ ′ −t ₁ ) / (t ₀ −t ₁ )

(A hardness)
The A hardness of the polishing pad was measured as follows. That is, a pressing needle (measuring element) is pressed onto the surface of a test piece (10 cm × 10 cm) having a thickness of 4.5 mm or more via a spring, and the pressing depth of the pressing needle after 30 seconds is measured by an A-type hardness meter (Nippon Kogyo). Standard, JIS K 7311). When the polishing pad had a thickness of less than 4.5 mm, the polishing pad was stacked until the thickness became 4.5 mm or more to obtain a test piece. This was performed three times to determine the A hardness of the polishing pad from the arithmetic mean.

(Tensile strength retention)
Using a tensile universal testing machine (“Tensilon”, manufactured by A & D, RTC-1210A), the tensile strength (a) of the polishing pad before being immersed in the test solution is measured in accordance with Japanese Industrial Standard (JIS K 6550). did. Subsequently, nitric acid was added to a 3% by mass aqueous potassium permanganate solution to adjust to pH 2 to prepare a test solution. The polishing pad was immersed in this test solution at 25 ° C. for 48 hours. The container containing the test solution and the polishing pad was shaken for several minutes after the lapse of 24 hours from the start of immersion. After 48 hours from the start of immersion, the polishing pad was removed from the test solution, washed with running water, and subjected to ultrasonic cleaning for 5 minutes. Subsequently, it was washed with running water, the remaining test solution was wiped off while being pressurized with kitchen paper, and the tensile strength (b) of the polishing pad was measured in the same manner as described above. From the values of tensile strength (a) and tensile strength (b) thus measured, the tensile strength retention was calculated by the following formula.
Tensile strength retention = tensile strength (b) / tensile strength (a) × 100 (%)

<Polishing test>
About the polishing pad of each Example and a comparative example, it grind | polished as shown below, and evaluated the polishing rate, generation | occurrence | production of a scratch, and deposition of brown silica.
First, the polishing pad obtained in each example was attached to the surface plate of a polishing machine (trade name “MCP-150X” manufactured by Fujikoshi Co., Ltd.), and the polishing surface of the polishing pad was dressed while supplying water at 900 mL / min. Processing (pressurization 1.3 kPa, time: 10 min). At that time, “Diamond Dresser (# 100)” manufactured by Asahi Diamond Industrial Co., Ltd. was used as the diamond dresser. Next, the object to be polished was a silicon wafer (diameter 8 inches × thickness 700 μm), and polishing was performed under the following polishing conditions.
(Polishing conditions)
Polishing liquid: As the polishing liquid containing colloidal silica, “GLANZOX HP-20” manufactured by Fujimi Incorporated was used, and the one prepared at a ratio of GLANZOX HP-20: water = 1: 19 was used.
Polishing fluid flow rate: 600 mL / min (without temperature adjustment)
Top rotation speed: 60 rpm
Platen rotation speed: 60rpm
Polishing time: 60 min / BT
Polishing pressure: 200 gf / cm ² (13.5 kpa)

(Polishing rate)
The polishing rate is expressed by dividing the polishing amount, which is the difference in thickness of the silicon wafer before and after polishing, by the polishing time, and was calculated by measuring the specific gravity and area of the silicon wafer and the weight difference before and after polishing.

(Scratch occurrence)
The surface of the object to be polished after the polishing process was targeted, and the presence or absence of scratches was visually evaluated according to the following criteria under the strong light of a halogen lamp.
○: Can hardly be confirmed.
Δ: Slightly confirmable.
X: It can confirm clearly.

(With or without brown silica)
The term “brown silica” as used herein means that silica derived from the abrasive grains of the polishing liquid has a volume on the surface of the polishing pad and serves as an index for clogging. With respect to the surface of the polishing pad after the polishing, the presence or absence of brown silica was visually evaluated according to the following criteria.
○: Almost no brown color.
Δ: Slightly brown.
X: The color is brown.

Claims (8)

A polishing pad having a nonwoven fabric, a first resin, and a second resin different from the first resin,
The second resin is a reaction product of a urethane prepolymer having an NCO equivalent of 500 or less, a polyalkylene ether glycol having a bifunctional or higher functionality and an OH equivalent of 500 to 10,000, and a curing agent,
A polishing pad, wherein the molar ratio of the amount of OH groups in the polyalkylene ether glycol to the amount of NCO groups in the urethane prepolymer is 0.01 to 0.15.   The ratio of the tensile strength of the polishing pad after immersing the polishing pad at 25 ° C. for 48 hours in a solution adjusted to pH 2 by adding nitric acid to a 3 mass% potassium permanganate aqueous solution to the tensile strength of the polishing pad is 45. The polishing pad according to claim 1, wherein the polishing pad is 45% or more.   The content of the nonwoven fabric is 10 to 50% by mass, and the content of the first resin is 10 to 60% by mass with respect to the total of the nonwoven fabric, the first resin, and the second resin. The polishing pad according to claim 1 or 2, wherein the content of the second resin is 10 to 70 mass%. The total molar ratio of the amount of OH groups in the polyalkylene ether glycol and the amount of NH ₂ groups in the curing agent to the amount of NCO groups in the urethane prepolymer is 0.8 to 1.0. The polishing pad of any one of -3. A primary impregnation step of obtaining a resin-impregnated nonwoven fabric by impregnating the nonwoven fabric with a resin solution containing the first resin and performing wet coagulation;
An immersion step of immersing the resin-impregnated nonwoven fabric in a solvent in which the first resin is soluble;
Secondary impregnating the resin-impregnated nonwoven fabric after the dipping step with a solution containing a urethane prepolymer having an NCO equivalent of 500 or less, a polyalkylene ether glycol having a bifunctional or higher functionality and an OH equivalent of 500 to 10,000, and a curing agent. An impregnation step;
Have
The manufacturing method of the polishing pad whose molar ratio of the quantity of OH group in the said polyalkylene ether glycol with respect to the quantity of NCO group in the said urethane prepolymer is 0.01-0.15.   The method for producing a polishing pad according to claim 5, wherein the first resin is soluble in one or more solvents selected from the group consisting of N, N-dimethylformamide, dimethylacetamide, and methyl ethyl ketone.   The method for producing a polishing pad according to claim 5 or 6, wherein the solvent contains one or more solvents selected from the group consisting of N, N-dimethylformamide, dimethylacetamide, and methyl ethyl ketone.   The polishing method of grind | polishing with the polishing pad of any one of Claims 1-4, making a compound semiconductor wafer contact the solution containing potassium permanganate.