JP2020157432A - Polishing pad, method for producing polishing pad, method for polishing surface of optical material or semiconductor material, and method for evaluating polishing pad - Google Patents

Abstract

To provide a polishing pad which suppresses dishing and erosion and can suppress occurrence of polishing scratches.SOLUTION: A polishing pad has a polishing layer containing a polyurethane resin, in which when a free induction decay signal (FID) obtained by pulse NMR is deducted in order from a long component of a spin-spin relaxation time T2 by a least square method, is subjected to waveform separation and thereby is divided into three components of an amorphous phase, an interface phase and a crystal phase in order from the long spin-spin relaxation time T2, the polishing layer has a ratio (Aa40/(Ai40+Ac40)) of a content ratio (Aa40) of the component of the amorphous phase at 40°C to the total of a content ratio (Ai40) of the component of the interface phase at 40°C and a content ratio (Ac40) of the component of the crystal phase at 40°C of 2-10, and a relaxation time of the component of the amorphous phase at 40°C of 500-800 μs.SELECTED DRAWING: Figure 5

Description

The present invention relates to a polishing pad, a method for manufacturing a polishing pad, a method for polishing the surface of an optical material or a semiconductor material, and a method for evaluating a polishing pad. The polishing pad of the present invention is used for polishing optical materials, semiconductor wafers, semiconductor devices, substrates for hard disks, etc., and is particularly suitable for polishing devices in which an oxide layer, a metal layer, etc. are formed on a semiconductor wafer. Used for.

In the manufacture of semiconductor devices such as LSIs, more delicate polishing is required as the structure becomes finer. There are a wide variety of manufacturing processes for devices that use CMP, and the performance that is emphasized differs for each process. Polishing by CMP consists of several polishing steps, and includes, for example, a step such as an STI step (shallow trench separation step), an ILD film, and a flattening of an IMD film. In these polishing steps, a semiconductor substrate or the like in which an oxide film such as TEOS and a nitride film such as silicon nitride are laminated is polished as an object to be polished. That is, in the semiconductor substrate, a nitride film is laminated as a stopper layer under the oxide film.

Since STI polishing polishes the portion in contact with the transistor portion, it is most sensitive to the occurrence of defects in the CMP process, and suppression of polishing scratches is particularly important. Further, since STI is the lowest layer of the device, it is important to control local flatness called erosion or dishing in this process.
Patent Document 1 discloses that as a polishing pad for finishing the surface of a device, a soft suede pad that is less likely to cause polishing scratches such as scratches is preferably used.

JP-A-2010-149259

In the CMP process, it is becoming important to reduce the dishing and erosion to improve the flattening characteristics and to reduce the polishing scratches in the CMP process. Since scratches that have not been a problem until now due to miniaturization of semiconductor devices become fatal defects, how to flatten without scratches becomes an important issue. Further, in recent years, in polishing for forming a fine structure, the amount of polishing is originally small, and there are cases where the reproducibility of processing is more important than the polishing rate. That is, in-wafer uniformity, interwafer uniformity, lot-to-lot uniformity, and the like.

An object of the present invention is to provide a polishing pad capable of suppressing dishing and erosion and further suppressing the occurrence of polishing scratches.

As a result of diligent research to solve the above problems, the present inventors have made a total of the content ratio of the component of the interface phase at 40 ° C. (Ai ₄₀ ) and the content ratio of the component of the crystal phase at 40 ° C. (Ac ₄₀ ). , The ratio of the content ratio (Aa ₄₀ ) of the amorphous phase component at 40 ° C. (Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ )), and the polishing layer in which the relaxation time of the amorphous phase at 40 ° C. is within a specific range are used. It was found that the above problems could be solved by this, and the present invention was completed. Specific embodiments of the present invention are as follows.

[1] A polishing pad having a polishing layer containing a polyurethane resin.
In the polishing layer, the free induction decay signal (FID) obtained by pulse NMR is subtracted in order from the component having the longest spin-spin relaxation time T2 by the minimum square method, and the waveform is separated to obtain the longer spin-spin relaxation time T2. When divided into three components, amorphous phase, interfacial phase, and crystalline phase, in order from the beginning, the content ratio of the interfacial phase component at 40 ° C. (Ai ₄₀ ) and the content ratio of the crystalline phase component at 40 ° C. (Ac ₄₀ ). The ratio (Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ )) of the content ratio (Aa ₄₀ ) of the amorphous phase component at 40 ° C. is 2 to 10 and the relaxation time of the amorphous phase component at 40 ° C. The polishing pad having a value of 500 to 800 μs.
[2] The ratio (Aa ₄₀ / Aa ₂₀ ) of the content ratio (Aa ₄₀ ) of the amorphous phase component at 40 ° C. to the content ratio (Aa ₂₀ ) of the amorphous phase component at 20 ° C. is 1.5 to 3. The polishing pad according to [1].
[3] The method for manufacturing a polishing pad according to [1] or [2], which comprises a step of using a wet film forming method.
[4] The method for polishing the surface of an optical material or a semiconductor material, which comprises the step of using the polishing pad according to [1] or [2].
[5] A method for evaluating a polishing pad having a polishing layer containing a polyurethane resin.
For the polishing layer, the free induction decay signal (FID) obtained by pulse NMR is subtracted in order from the component having the longest spin-spin relaxation time T2 by the minimum square method, and the waveform is separated to obtain the longer spin-spin relaxation time T2. When divided into three components, amorphous phase, interfacial phase, and crystalline phase, in order from the beginning, the content ratio of the component of the interfacial phase at 40 ° C. (Ai ₄₀ ) and the content ratio of the component of the crystalline phase at 40 ° C. (Ac ₄₀ ). The ratio of the content ratio (Aa ₄₀ ) of the amorphous phase component at 40 ° C. to the total of (Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ )) is 2 to 10, and the relaxation time of the amorphous phase at 40 ° C. is 500. The evaluation method including a step of confirming whether or not it is ~ 800 μs.
[6] The ratio (Aa ₄₀ / Aa ₂₀ ) of the content ratio (Aa ₄₀ ) of the amorphous phase component at 40 ° C. to the content ratio (Aa ₂₀ ) of the amorphous phase component at 20 ° C. is 1.5 to 3. The evaluation method according to [5], further comprising a step of confirming the presence or absence.

The polishing pad of the present invention can suppress dishing and erosion, and further suppress the occurrence of polishing scratches.

It is a figure explaining the structure analysis method of the polishing pad by pulse NMR. It is a schematic diagram which shows an example of the apparatus which performs the steps of coating, solidification regeneration, cleaning / drying in the manufacturing process of the polishing pad of this invention. It is a figure which shows the cross-sectional view of an example of the polishing pad of this invention. It is a figure explaining the polishing method of the object to be polished using the polishing pad of this invention. It is a graph which shows the result (relaxation time of each component) of the structural analysis by the pulse NMR of the polishing pad obtained in Examples 1 and 2 and Comparative Example 1. It is a graph which shows the result (content ratio of each component) of the structural analysis by the pulse NMR of the polishing pad obtained in Examples 1 and 2 and Comparative Example 1. It is a photograph which shows the cross section of the polishing pad obtained in Example 1 and Comparative Example 1.

(Action)
In the present invention, as the polishing layer, the component of the amorphous phase at 40 ° C. with respect to the total of the content ratio of the component of the interface phase at 40 ° C. (Ai ₄₀ ) and the content ratio of the component of the crystalline phase at 40 ° C. (Ac ₄₀ ). The ratio of the content ratio (Aa ₄₀ ) of (Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ )) is 2 to 10, and the relaxation time of the amorphous phase at 40 ° C. is 500 to 800 μs.

The present inventors unexpectedly used a polishing layer in which Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ ) was 2 to 10 and the relaxation time of the amorphous phase at 40 ° C. was 500 to 800 μs. It has been found that erosion can be suppressed and the occurrence of polishing scratches can be further suppressed. The details of the reason why these characteristics are obtained are not clear, but it is inferred as follows.

Regarding polishing with a polishing pad, the temperature of the polishing surface of the polishing pad at the beginning of polishing is around room temperature (about 20 ° C), but the temperature of the polishing surface from the middle to the latter stage of polishing is around 40 ° C due to frictional heat and the like. Ascend to.
Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ ) corresponds to the proportion of the amorphous phase component at the temperature (about 40 ° C.) of the polished surface in the middle to late polishing period, and the proportion of the amorphous phase component is in the polyurethane resin. It is considered to mean the ratio of the region (soft segment component) where the molecular chain is not constrained and is easy to move. In the polishing pad of the present invention, the content ratio of the amorphous phase is more than twice as large as the content ratio of the interface phase and the crystalline phase combined, and the molecular chain is not constrained and occupies most of the region where the movement is easy. The region where the molecular chains are constrained and difficult to move (the total of the interface phase and the crystal phase) is smaller than 33% of the total. Therefore, it is considered that the polishing pad of the present invention can be polished without giving polishing scratches.

Further, the component of the amorphous phase is considered to correspond to the soft segment component, and a large relaxation time of the amorphous phase means that the mobility of the amorphous phase is larger than that of a component having a short relaxation time. .. In the polishing pad of the present invention, since the relaxation time of the amorphous phase component is 500 to 800 μs, the convex portion can be selectively polished and the polishing of the concave portion can be suppressed. For example, the oxide film is polished. In the STI process, which must be stopped by the nitride film, the polishing selectivity of the oxide film can be improved with respect to the nitride film. In general, dishing and erosion correlate with the rigidity of the pad, and the harder the pad, the better the dishing and erosion characteristics. When the relaxation time is in the range of 500 to 800 μs, the pad has the same degree of motility as the relaxation time of a pad having a higher rigidity than the present invention, and has an appropriate elongation recovery property. Therefore, polishing having concave protrusions. It is thought that subduction to the recesses on the surface is suppressed and dishing and erosion can be suppressed. In a pad having a rigidity larger than that of the present invention, such as Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ ) of 1 or more and less than 2, even if the relaxation time is 500 to 800 μs and the subduction to the recess is suppressed, the pad is in the recess. It is considered that the grinding force at the time of contact is superior and the dishing and erosion deteriorate.

(Structural analysis by pulse NMR)
In pulse NMR, a FID signal having excellent quantification can be obtained by detecting a response signal to a pulse. Therefore, the phase-separated structure of the polyurethane resin can be analyzed. The initial value of the FID signal is proportional to the number of protons in the measurement sample, and if the measurement sample has a plurality of components, the FID signal is the sum of the response signals of each component. If there is a difference in the motility of each component, the speed of attenuation of the response signal is different and the spin-spin relaxation time T2 is different. Therefore, it is necessary to separate these and obtain the relaxation time T2 and the component ratio R of each component. it can. The smaller the motility of the component, the shorter the relaxation time T2, and the larger the motility, the longer the relaxation time T2. In other words, the shorter the relaxation time T2, the greater the crystallinity, and the longer the relaxation time T2, the greater the amorphousness.

As shown in FIG. 1, the FID signal obtained by pulse NMR of the polyurethane resin is shown by the curve D. By subtracting from the curve D in order from the component having the longest relaxation time T2 by the least squares method and separating the waveforms, it can be divided into the three components shown by the curve H, the curve S, and the curve I. The component having a long relaxation time T2 shown by the curve S corresponds to the amorphous phase, and the component having a short relaxation time T2 shown by the curve H corresponds to the crystalline phase. The component represented by the curve I between the curve S and the curve H corresponds to the interface phase. In the polyurethane resin, the component ratio of the amorphous phase formed by the soft segment having high motility correlates with the compressive elastic modulus, and the component ratio of the crystalline phase formed by the hard segment having low motility correlates with the A hardness. Therefore, the compressive elastic modulus can be increased by increasing the component ratio of the amorphous phase, and the A hardness can be increased by increasing the component ratio of the crystalline phase.

Hereinafter, the polishing pad of the present invention, a method for manufacturing the polishing pad, a method for polishing the surface of an optical material or a semiconductor material, and a method for evaluating the polishing pad will be described.
In the present specification and the claims, when the numerical range is expressed by using "A to B", the range shall include A and B which are the numerical values at both ends.

(Polishing pad)
The polishing pad of the present invention is a polishing pad having a polishing layer containing a polyurethane resin, and the polishing layer obtains a free induction decay signal (FID) obtained by pulse NMR by a minimum square method and has a spin-spin relaxation time T2. By subtracting the components in order from the longest component and separating the waveforms, the components of the interface phase at 40 ° C. are contained when the spin-spin relaxation time T2 is divided into three components in order from the longest component: amorphous phase, interfacial phase, and crystalline phase. The ratio of the content ratio of the amorphous phase component (Aa ₄₀ ) at 40 ° C to the sum of the ratio (Ai ₄₀ ) and the content ratio of the crystalline phase component at 40 ° C (Ac ₄₀ ) (Aa ₄₀ / (Ai ₄₀ + Ac)). ₄₀ )) is 2 to 10, and the relaxation time of the amorphous phase component at 40 ° C. is 500 to 800 μs.
Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ ) is 2 to 10, preferably 6 to 9.5, and more preferably 7 to 9. The relaxation time of the amorphous phase component at 40 ° C. is 500 to 800 μs, preferably 620 to 780 μs, and more preferably 650 to 750 μs. When the relaxation time of the amorphous phase component at Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ ) and 40 ° C. is within the above numerical range, a polishing pad capable of suppressing dishing and erosion and further suppressing the occurrence of polishing scratches can be obtained. ..

Aa ₄₀ is preferably 70 to 95%, more preferably 75 to 95%, and most preferably 80 to 95%. Ai ₄₀ is preferably 1 to 10%, more preferably 2 to 8%, and most preferably 3 to 7%. Ac ₄₀ is preferably 1 to 10%, more preferably 2 to 8%, and most preferably 3 to 7%.

The polyurethane resin (polishing layer) in which Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ ) is 2 to 10 is obtained by setting the 100% resin modulus (MPa) of the polyurethane resin used for the polishing layer to 7 MPa or less. Such a polyurethane resin having a small modulus usually stretches well and returns slowly after releasing the applied force, but in the polyurethane resin of the present application, the relaxation time of the amorphous phase component at 40 ° C. is 500 to 800 μs. By doing so, the 100% modulus has the same degree of molecular mobility as the polyurethane resin having a greater than 5 MPa. By setting the relaxation time of the amorphous phase component at 40 ° C. in such a range, it is possible to improve the returnability after releasing the applied force while having low modulus, and the responsiveness of the polishing pad is improved. However, it is possible to suppress dishing and erosion by improving the step performance.
The 100% resin modulus of the polyurethane resin contained in the polishing layer is preferably 1 to 7 MPa, more preferably 1.5 to 6 MPa. The 100% resin modulus of polyurethane resin is an index showing the hardness of the resin, and the load applied when the non-foamed resin sheet is stretched 100% (when stretched to twice the original length) is the cross-sectional area. It is the divided value. For 100% resin modulus, the resin solution is thinly stretched and dried with hot air to prepare a dry film with a thickness of about 200 μm, and after curing for a while, the total length of the measuring part is 90 mm, the width of both ends is 20 mm, the distance between the grippers is 50 mm, and the parallel part. The sample is punched into a dumbbell shape with a width of 10 mm and a thickness of 200 μm, and the measurement sample is measured at 20 ° C. (± 2) using a universal material tester Tencilon (Tencilon universal tester “RTC-1210” manufactured by A & D Co., Ltd.). ℃), humidity 65% (± 5%), pulling at a pulling speed of 100 mm / min, and dividing the tension at 100% elongation (double stretching) by the initial cross-sectional area of the sample. To measure the resin modulus, a polyurethane foam sheet is dissolved in N, N-dimethylformamide (DMF) to obtain a low-concentration polyurethane resin DMF solution, and then the DMF is vaporized by a casting method to obtain a non-foamed resin sheet. It can also be measured by forming.
The weight average molecular weight of the polyurethane resin contained in the polishing layer is preferably 100,000 to 200,000, more preferably 11,000 to 160,000, and most preferably 12,000 to 14,000. The weight average molecular weight of the polyurethane resin can be measured by gel permeation chromatography by the method described later.

The relaxation time of the amorphous phase component at 40 ° C. can be adjusted by adjusting the type and molecular weight of the polymer diol, or adjusting the amount of the chain extender or the terminal encapsulant.

The polishing pad of the present invention has a ratio (Aa ₄₀ / Aa ₂₀ ) of the content ratio (Aa ₄₀ ) of the amorphous phase component at 40 ° C. to the content ratio (Aa ₂₀ ) of the amorphous phase component at 20 ° C. It is preferably 5 to 3, more preferably 1.8 to 2.8, and most preferably 2 to 2.5.
Since Aa ₄₀ / Aa ₂₀ is within the above numerical range, the ratio of the components of the interface phase is large and the region where the molecular chain is constrained is large at the low temperature (about 20 ° C.) at the initial stage of polishing. It is considered that this improves the elasticity of the polishing pad and contributes to the improvement of the rising property. Further, when the temperature of the polishing pad rises in the middle to late stages of polishing (about 40 ° C.), the proportion of amorphous phase components becomes sufficiently large, and it is considered that polishing scratches can be reduced.

Aa ₂₀ is preferably 25 to 60%, more preferably 30 to 50%, and most preferably 35 to 45%.

The content ratio of the components of the interface phase at 20 ° C. is preferably 30 to 55%, more preferably 35 to 53%, and most preferably 40 to 50%. The content ratio of the components of the crystal phase at 20 ° C. is preferably 5 to 20%, more preferably 8 to 18%, and most preferably 10 to 15%.
The relaxation time of the amorphous phase component at 20 ° C. is preferably 800 to 1300 μs, more preferably 900 to 1250 μs, and most preferably 1000 to 1200 μs. The relaxation time of the components of the interface phase at 20 ° C. is preferably 100 to 300 μs, more preferably 150 to 280 μs, and most preferably 180 to 250 μs. The relaxation time of the crystal phase components at 20 ° C. is preferably 10 to 30 μs, more preferably 15 to 28 μs, and most preferably 18 to 25 μs.
The relaxation time of the components of the interface phase at 40 ° C. is preferably 10 to 50 μs, more preferably 15 to 40 μs, and most preferably 20 to 35 μs. The relaxation time of the crystal phase components at 40 ° C. is preferably 5 to 30 μs, more preferably 10 to 25 μs, and most preferably 15 to 20 μs.

(Polyurethane resin composition)
The polyurethane resin of the polishing pad of the present invention is obtained by reacting a polyisocyanate compound with a curing agent such as polyol or polyamine, and a chain extender can also be used. The crystalline phase (hard segment) is composed of structural units derived from an isocyanate compound and a chain extender, and the amorphous phase (soft segment) is a structural unit derived from a polyol or diamine having an aliphatic organic group having a relatively high degree of freedom. Consists of.

The polyisocyanate compound can be used in the form of a prepolymer obtained by reacting the polyisocyanate compound with a polyol in advance to increase the molecular weight.

Examples of the polyisocyanate compound include aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, phenylenedi isocyanate, and xylylene diisocyanate: hexamethylene diisocyanate, isophorone diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and hydrogenated. Examples thereof include aliphatic or alicyclic diisocyanates such as tolylene diisocyanate and hydrogenated xylylene diisocyanate.

Examples of the polyol (polymer diol) include polyether diols, polyester diols, polycarbonate diols and the like. These polymer diols may be used alone or in combination of two or more. Among these, it is preferable to use a polyether diol from the viewpoint of reducing polishing scratches.
Examples of the polyether diol include poly (ethylene glycol), poly (propylene glycol), poly (tetramethylene glycol), poly (methyltetramethylene glycol) and the like. These polyether diols may be used alone or in combination of two or more.
The polyester diol can be produced, for example, by directly subjecting an ester-forming derivative such as a dicarboxylic acid or an ester thereof or an anhydride to a low molecular weight diol by a transesterification reaction or a transesterification reaction.
Examples of the dicarboxylic acid constituting the polyesterdiol include succinic acid, glutaric acid, adipic acid, pimeric acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, 2-methylsuccinic acid, 2-methyladipic acid, 3-. An aliphatic dicarboxylic acid having 4 to 12 carbon atoms such as methyl adipic acid, 3-methylpentanedioic acid, 2-methyloctanedioic acid, 3,8-dimethyldecanedioic acid, and 3,7-dimethyldecanedioic acid; terephthalic acid. , Aromatic dicarboxylic acids such as isophthalic acid and orthophthalic acid; and the like. These dicarboxylic acids may be used alone or in combination of two or more.
Examples of the low molecular weight diol constituting the polyester diol include ethylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, neopentyl glycol, and 1,5-pentane. Diol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, 1,8-octanediol, 2-methyl-1,8-octanediol, 1,9-nonanediol, 1,10-decane An aliphatic diol such as a diol; an alicyclic diol such as cyclohexanedimethanol and a cyclohexanediol; and the like can be mentioned. These low molecular weight diols may be used alone or in combination of two or more. Examples of the carbon number of the low molecular weight diol include 6 or more and 12 or less.

Examples of the chain extender include ethylene glycol, diethylene recall, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, hexamethylene glycol, saccharose, and methylene glycol. , Glycerin, sorbitol and other aliphatic polyol compounds; bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenylsulfone, hydrogenated bisphenol A, hydroquinone and other aromatic polyols. Compounds, water and the like can be used. These chain extenders may be used alone or in combination of two or more.

(Other ingredients)
The polyurethane resin composition of the present invention can contain additives. The additive is preferably selected from the group consisting of a film forming aid and a foaming inhibitor.
Examples of the film forming aid include hydrophobic activators and the like. Examples of the hydrophobic activator include polyoxyethylene alkyl ether, polyoxypropylene alkyl ether, polyoxyethylene polyoxypropylene alkyl ether, perfluoroalkylethylene oxide adduct, glycerin fatty acid ester, propylene glycol fatty acid ester, and polyether modification. Examples thereof include nonionic surfactants such as silicon and anionic surfactants such as alkylcarboxylic acids.
Examples of the foaming inhibitor include hydrophilic activators and the like. Examples of the hydrophilic activator include anionic surfactants such as carboxylates, sulfonates, sulfates and phosphates, and cellulose esters.
When the film forming aid is added as an additive, it is preferably 0.2 to 10% by mass. When the foaming inhibitor is added as an additive, it is preferably 0.2 to 10% by mass.

(Polymerization reaction of polyurethane resin composition)
The polyurethane resin can be produced by polymerizing the above-mentioned polyurethane resin composition. That is, a method of carrying out the polymerization reaction in an organic solvent and the like can be mentioned.
The polyurethane resin obtained under the above reaction conditions is mixed with a solvent such as DMF and then supplied to a film forming apparatus as shown in FIG. 2 to be molded into a polyurethane sheet.

(Manufacturing method of polishing pad)
The method for manufacturing a polishing pad of the present invention is the above-mentioned method for manufacturing a polishing pad, and includes a step of using a wet film forming method.

Hereinafter, the method for manufacturing the polishing pad of the present invention will be described with reference to the drawings.
FIG. 3 shows a cross-sectional view of an example of the polishing pad of the present invention. The polishing pad 1 of the present invention has a polyurethane sheet 2 as a soft plastic foam manufactured by a wet film forming method. The polyurethane sheet 2 is buffed on the polished surface P side so that the thickness of the polyurethane sheet 2 (length in the vertical direction in FIG. 3) becomes substantially uniform (details will be described later).

In the polyurethane sheet 2, the skin layer formed on the surface side by the wet film forming method is removed by buffing. The buffing process constitutes a polished surface P for polishing the object to be polished. Inside the polyurethane sheet 2, foams 3 having a substantially triangular cross section and rounded along the thickness direction of the polyurethane sheet 2 are formed. The space volume of the foam 3 is formed so that the size of the polished surface P side is smaller than that of the back surface side of the polished surface P. In the polyurethane resin between the foams 3, microfoams having a space volume smaller than that of the foams 3 are formed. Foam 3 and microfoam are connected in a three-dimensional network through communication holes.

Further, in the polishing pad 1, the base material 8 (polyethylene terephthalate resin sheet having a thickness of 188 μm) and the surface of the buffed polyurethane sheet 2 opposite to the buffed surface are bonded to each other using an acrylic adhesive. ing. A double-sided tape for mounting the polishing pad 1 on the polishing machine is attached to the surface of the base material 8 opposite to the surface attached to the polyurethane resin sheet. In the double-sided tape, the adhesive layer on the other side (opposite side to the base material 8) is covered with a release paper.

A polyurethane sheet 2 is produced by a wet film forming method, and a base material 8 is attached to the polyurethane sheet 2. That is, in the wet film-forming method, a polyurethane resin solution in which a polyurethane resin is dissolved in an organic solvent is continuously applied to a film-forming substrate and immersed in an aqueous coagulation liquid to coagulate and regenerate the polyurethane resin into a film. After washing, it is dried to prepare a strip-shaped (long-shaped) polyurethane sheet 2. Hereinafter, the steps will be described in order.

In the preparatory step, the polyurethane resin, N, N-dimethylformamide (hereinafter abbreviated as DMF), which is a water-miscible organic solvent capable of dissolving the polyurethane resin, and an additive are mixed to dissolve the polyurethane resin. For example, the polyurethane resin is dissolved in DMF to a concentration of 30% by weight. As the additive, a hydrophilic activator that promotes foaming, a hydrophobic activator that stabilizes the solidification and regeneration of the polyurethane resin, and the like can be used in order to control the size and amount (number) of the foaming 3. After removing agglomerates and the like by filtering the obtained solution, defoaming is performed under vacuum to obtain a polyurethane resin solution.

In the coating step, coagulation / regeneration step, and cleaning / drying step, the polyurethane resin solution obtained in the preparation step is continuously applied to the film-forming substrate and immersed in an aqueous coagulation liquid to coagulate and regenerate the polyurethane resin for cleaning. After that, it is dried to obtain a polyurethane sheet 2. The coating step, the solidification regeneration step, and the cleaning / drying step are continuously executed by, for example, the film forming apparatus shown in FIG.

As shown in FIG. 2, the film forming apparatus 60 is filled with a pretreatment liquid 15 such as water or a DMF aqueous solution (mixed solution of DMF and water) for pretreating the non-woven fabric or woven fabric of the film forming base material. Pretreatment tank 10, coagulation tank 20 filled with coagulation liquid 25 containing water, which is a poor solvent for polyurethane resin, for coagulation and regeneration of polyurethane resin, water for cleaning polyurethane resin after coagulation and regeneration A cleaning tank 30 filled with a cleaning liquid 35 such as the above and a cylinder dryer 50 for drying the polyurethane resin are continuously provided.

A base material supply roller 41 for supplying the film-forming base material 43 is arranged on the upstream side of the pretreatment tank 10. The pretreatment tank 10 has a pair of guide rollers 13 at the lower inside of a substantially central portion in the same longitudinal direction as the transport direction of the film-forming base material 43. Guide rollers 11 and 12 are arranged on the base material supply roller 41 side above the pretreatment tank 10, and an excess pretreatment liquid contained in the pretreated film-forming base material 43 is arranged on the solidification tank 20 side. A mangle roller 18 for removing 15 is arranged. On the downstream side of the mangle roller 18, a knife coater 46 for substantially uniformly applying the polyurethane resin solution 45 to the film-forming base material 43 is arranged. A guide roller 21 is arranged above the coagulation tank 20 on the downstream side of the knife coater 46.

In the coagulation tank 20, a guide roller 23 is arranged at the lower inside on the cleaning tank 30 side. A mangle roller 28 for dehydrating the polyurethane resin after solidification and regeneration is arranged above the solidification tank 20 and on the cleaning tank 30 side. A guide roller 31 is arranged above the washing tank 30 on the downstream side of the mangle roller 28. In the cleaning tank 30, four guide rollers 33 at the top and five guide rollers 33 at the bottom are arranged alternately in the vertical direction, which is the same as the transport direction of the film-forming base material 43. A mangle roller 38 for dehydrating the polyurethane resin after cleaning is arranged above the cleaning tank 30 and on the cylinder dryer 50 side. In the cylinder dryer 50, four cylinders having a heat source inside are arranged in four upper and lower stages. On the downstream side of the cylinder dryer 50, a take-up roller 42 for winding the dried polyurethane resin (along with the film-forming base material 43) is arranged. The mangle rollers 18, 28, 38, the cylinder dryer 50, and the take-up roller 42 are connected to a rotary drive motor (not shown), and the film-forming base material 43 is a base material supply roller by these rotational drive forces. It is conveyed from 41 to the take-up roller 42. The transport speed of the film-forming substrate 43 is set to, for example, 2.5 m / min, and is preferably set in the range of 1.0 to 5.0 m / min.

When a non-woven fabric or a woven fabric is used as the film-forming base material 43, the film-forming base material 43 is pulled out from the base material supply roller 41 and continuously introduced into the pretreatment liquid 15 via the guide rollers 11 and 12. .. By passing the film-forming base material 43 between the pair of guide rollers 13 in the pretreatment liquid 15 to perform pretreatment (sealing), when the polyurethane resin solution 45 is applied, the film-forming base material 43 is inside. The penetration of the polyurethane resin solution 45 of the above is suppressed. After the film-forming base material 43 is pulled up from the pretreatment liquid 15, the film-forming base material 43 is pressed by the mangle roller 18 to draw down the excess pretreatment liquid 15. The film-forming base material 43 after the pretreatment is conveyed in the direction of the solidification tank 20. When a flexible film made of PET or the like is used as the film-forming base material 43, pretreatment is not required, so that the film is fed directly from the guide roller 12 to the mangle roller 18 or into the pretreatment tank 10. The pretreatment liquid 15 may not be added. Hereinafter, in this example, the film-forming base material 43 will be described as a PET film.

In the coating step, the polyurethane resin solution 45 prepared in the preparatory step is substantially uniformly coated on the film-forming substrate 43 by the knife coater 46 at room temperature. At this time, the coating thickness (coating amount) of the polyurethane resin solution 45 is adjusted by adjusting the gap (clearance) between the knife coater 46 and the upper surface of the film-forming base material 43.

In the solidification / regeneration step, the film-forming base material 43 coated with the polyurethane resin solution 45 by the knife coater 46 is introduced into the coagulation liquid 25 from the guide roller 21 toward the guide roller 23. In the coagulation liquid 25, first, a skin layer 4 having a thickness of several μm is formed on the surface of the applied polyurethane resin solution 45. After that, as the replacement of DMF in the polyurethane resin solution 45 with the coagulating liquid 25 progresses, the polyurethane resin is solidified and regenerated on one side of the film-forming base material 43. The solidification / regeneration of the polyurethane resin is completed between the time when the film-forming base material 43 coated with the polyurethane resin solution 45 enters the coagulation liquid 25 and the time it reaches the guide roller 23. When the DMF is desolvated from the polyurethane resin solution 45, foam 3 is formed in the polyurethane resin. At this time, since the film-forming base material 43 of the PET film does not allow water to permeate, desolvation occurs on the surface side of the polyurethane resin solution 45, and foam 3 having a film-forming base material 43 side larger than the surface side is formed. The coagulated and regenerated polyurethane resin is pulled up from the coagulating liquid 25, the excess coagulating liquid 25 is squeezed out by the mangle roller 28, and then transported to the cleaning tank 30 via the guide roller 31 and introduced into the cleaning liquid 35.

In the washing / drying step, the polyurethane resin is washed by passing the polyurethane resin introduced into the cleaning liquid 35 through the guide rollers 33 alternately up and down. After cleaning, the polyurethane resin is pulled up from the cleaning liquid 35, and the excess cleaning liquid 35 is squeezed out by the mangle roller 38. Then, the polyurethane resin is dried by passing it alternately between the four cylinders of the cylinder dryer 50 (in the direction of the arrow in FIG. 2) along the peripheral surface of the cylinders. The dried polyurethane resin (polyurethane sheet 2) is wound around the winding roller 42 together with the film-forming base material 43.

In the buffing step, the skin layer side of the film-forming resin is buffed so that the thickness becomes uniform. The polyurethane sheet 2 wound around the winding roller 42 is formed on a PET film of the film-forming base material 43. Since the thickness of the polyurethane sheet 2 varies during film formation, irregularities are formed on the polished surface P. After the film-forming base material 43 is peeled off, the surface of the pressure-welding jig having a substantially flat surface is pressed against the surface of the film-forming resin on the side opposite to the skin layer, so that irregularities appear on the skin layer side. The unevenness that appears on the skin layer side is removed by buffing. In this example, since the continuously produced polyurethane sheet 2 is strip-shaped, the skin layer side is continuously buffed while the pressure welding jig is pressed against the polished surface P. As a result, the thickness of the polyurethane sheet 2 from which the skin layer has been removed and the flat polished surface has been formed is eliminated, and openings are formed.

In the bonding step, the base material 8 (polyethylene terephthalate resin sheet having a thickness of 188 μm) and the surface of the buffed polyurethane sheet 2 opposite to the buffed surface are bonded using an acrylic adhesive.

In the laminating process, the double-sided tape is attached to the surface of the base material 8 opposite to the surface to which the polyurethane resin sheet is attached. After embossing the polished surface P, it is cut into a desired shape such as a circle in a cutting / inspection process. The embossing pattern is not particularly limited, and it is sufficient that the slurry moves smoothly during the polishing process. Then, an inspection such as confirming that there is no dirt or foreign matter adhered is performed to complete the polishing pad 1.

(Method of polishing the surface of optical material or semiconductor material)
The method of polishing the surface of an optical material or a semiconductor material of the present invention includes the step of using the above-mentioned polishing pad.

Hereinafter, the polishing method using the polishing pad of the present invention will be described with reference to the drawings.
When polishing the object to be polished, for example, as shown in FIG. 4, a single-sided polishing machine 70 is used. The single-sided polishing machine 70 has a pressure surface plate 72 for pressing an object to be polished on the upper side and a rotatable rotary surface plate 71 on the lower side. Both the lower surface of the pressure surface plate 72 and the upper surface of the rotary surface plate 71 are formed flat. A back pad 75 is attached to the lower surface of the pressure surface plate 72, and a polishing pad 1 for polishing an object to be polished is attached to the upper surface of the rotary surface plate 71. A template made of glass epoxy, bakelite, or the like is attached to the surface of the back pad 75, and an opening into which the object to be polished 78 can be inserted is formed in a substantially central portion of the template. By impregnating the back pad 75 exposed at the opening of the template with an appropriate amount of water and pressing the object to be polished 78, the object to be polished 78 is held by the back pad 75 by the surface tension of water and the adhesiveness of the polyurethane resin. .. By rotating the rotary surface plate 71 while pressurizing the object to be polished 78 with the pressure surface plate 72, the lower surface (processed surface) of the object to be polished 78 is polished by the polishing pad 1.

(Evaluation method of polishing pad)
The method for evaluating a polishing pad of the present invention is a method for evaluating a polishing pad having a polishing layer containing a polyurethane resin, and spins a free induction decay signal (FID) obtained by pulse NMR on the polishing layer by a minimum square method. By subtracting the components having the longest spin-spin relaxation time T2 in order and separating the waveforms, the three components of the amorphous phase, the interfacial phase, and the crystalline phase are divided in order from the longest spin-spin relaxation time T2, and at 40 ° C. the ratio of the sum of the content of components of the crystalline phase _{(Ac 40)} in proportion _{(Ai 40)} and 40 ° C. of the components of the interface phase, the proportion of the components of the amorphous phase at ₄₀ ℃ _(Aa 40) _{(Aa It} includes a step of confirming whether or not ₄₀ / (Ai ₄₀ + Ac ₄₀ )) is 2 to 10 and the relaxation time of the amorphous phase at 40 ° C. is 500 to 800 μs.

In the method for evaluating a polishing pad of the present invention, the ratio of the content ratio of the amorphous phase component (Aa ₄₀ ) at 40 ° C. to the content ratio (Aa ₂₀ ) of the amorphous phase component at 20 ° C. (Aa ₄₀ / Aa ₂₀ ). A step of confirming whether or not is 1.5 to 3 can be further included.

In the method for evaluating a polishing pad of the present invention, the numerical ranges of Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ ), the relaxation time of the amorphous phase at 40 ° C., and Aa ₄₀ / Aa ₂₀ are those described in the above (polishing pad). Can be used.

The present invention will be described experimentally with the following examples, but the following description is not intended to be construed as limiting the scope of the invention to the following examples.

(Example 1)
A polyester polyurethane resin obtained by condensing a polyester diol obtained by reacting a polyol having adipic acid and 1,4-butanediol as a constituent unit with 4,4'-diphenylmethane diisocyanate (MDI) (hereinafter, "" Polyurethane resin (1) ") was prepared. The 100% resin modulus of the polyurethane resin (1) was 6.0 MPa, and the weight average molecular weight was 137,900.
In this embodiment, the 100% resin modulus means a value obtained by dividing the load applied when the non-foamed resin sheet is stretched 100% (when stretched to twice the original length) by the cross section. .. For 100% resin modulus, a resin solution is thinly stretched and dried with hot air to prepare a dry film having a thickness of about 200 μm, and after curing for a while, the total length is 90 mm, the width at both ends is 20 mm, the distance between grippers is 50 mm, and the width of parallel parts is 10 mm. The sample is punched into a dumbbell shape with a thickness of 200 μm, and the measurement sample is sandwiched between the upper and lower air chucks of the universal material tester Tencilon (Tencilon universal tester "RTC-1210" manufactured by A & D Co., Ltd.) and 20 ° C. (± 2). It was determined by pulling at a tensile speed of 100 mm / min in an atmosphere of 65% (± 5%) humidity (° C.) and dividing the tension at 100% elongation (double stretching) by the initial cross-sectional area of the sample.
Further, in this embodiment, the weight average molecular weight means that measured by GPC under the measurement conditions described later.

The above polyurethane resin was dissolved in DMF to obtain a DMF solution having a concentration of the polyurethane resin (1) of 30%. A resin-containing solution was obtained by adding 50 parts by mass of DMF and 5 parts by mass of polyether-modified silicone as an additive to 100 parts by mass of the obtained polyurethane DMF solution and mixing them.
Next, a PET film is prepared as a base material for film formation, and the above resin-containing solution is applied thereto with a knife coater to a thickness of 1.0 mm and immersed in a coagulation bath (coagulation liquid: water). The resin-containing solution was coagulated, washed and dried, and then peeled off from the PET film to obtain a resin film (thickness 1.0 mm). The skin layer side formed on the surface of the obtained resin film was ground (grinding amount: 200 μm). Then, a part of the resin film was embossed with a grid-like mold to obtain a polishing pad.

(Example 2)
A polyester diol having a 100% resin modulus of 4.0 MPa and a weight average molecular weight of 132800 and obtained by reacting a polyol having adipic acid and 1,4-butanediol as constituent units, and 4,4'-diphenylmethane diisocyanate ( A polyester-based polyurethane resin (hereinafter referred to as “polyurethane resin (2)”) obtained by condensing with MDI) was prepared.
The above polyurethane resin was dissolved in DMF to obtain a DMF solution in which the concentration of the polyurethane resin (2) was 30%. To 100 parts by mass of the obtained polyurethane DMF solution, 50 parts by mass of DMF, 5 parts by mass of polyether-modified silicone, 1 part by mass of acetylbutyl cellulose, 1 part by mass of nonionic surfactant, and 1 part by mass of cellulose ester were added as additives. And mixed to obtain a resin-containing solution.
After that, a resin film was prepared in the same manner as in Example 1 to obtain a polishing pad.

(Comparative Example 1)
Instead of the polyurethane resin (1) of Example 1, a polyester diol obtained by reacting a polyol having adipic acid and 1,4-butanediol as a constituent unit and 4,4'-diphenylmethane diisocyanate (MDI) are used. A polyester-based polyurethane resin (hereinafter, “polyurethane resin (3)”) obtained by condensation was prepared. The 100% resin modulus of the polyurethane resin (3) was 8.5 MPa, and the weight average molecular weight was 137700.
After that, a resin film was prepared in the same manner as in Example 1 to obtain a polishing pad.

(Evaluation method)
The following GPC measurement and pulse NMR measurement were performed on each of the polishing pads of Examples 1 and 2 and Comparative Example 1. Further, the polishing pads of Examples 1 and 2 and Comparative Example 1 were subjected to a polishing test, and the polishing selectivity and the polishing scratches were evaluated.

(GPC measurement)
From each of the polishing pads obtained in Examples 1 and 2 and Comparative Example 1, 0.05 g of the polyurethane resin of the polishing layer was cut out, dissolved in 4.95 g of DMF to prepare a 1% polyurethane DMF solution, allowed to stand, and then tested. It was shaken at 50 ° C. for 14 hours with a tube mixer. After shaking, 0.5 g of the supernatant was measured and mixed with 2 g of DMF to prepare a 0.2% polyurethane DMF solution, which was then filtered through a 0.45 μm filter to prepare a measurement sample. The obtained measurement sample was measured by gel permeation chromatography (GPC) under the following conditions. A calibration curve was prepared using polyethylene glycol oxide (EasiVial PEG / PEO manufactured by Agilent Technologies, Inc.) as a standard sample.
(Measurement condition)
Column: Ohpak KB-805HQ (exclusion limit 2000000)
Mobile phase: 5 mM LiBr / DMF
Flow velocity: 0.75 ml / min (21 kg / cm ² )
Oven: 60 ° C
Detector: RI
Sample volume: 30 μl

(Pulse NMR)
The polishing pads of Examples 1 and 2 and Comparative Example 1 were structurally analyzed by pulse NMR under the following conditions.

Under the above equipment and conditions, the land portion of the obtained embossed polishing pad is cut out with a cutter, and a sample piece of about 1 to 3 mm square is filled in a 10 mmφ sample tube to a height of 1 to 2 cm, and pulse NMR is performed. The attenuation curve was obtained by performing the measurement of. Analysis was performed by the least squares method using the Lorenz function (straight line part) and Gaussian function (curve part) so that the obtained decay curve and fitting curve match, and the crystalline phase, interfacial phase, and non-crystalline phase in the polishing layer were analyzed. The ratio (absence ratio (%)) and relaxation time (T2) were obtained. For fitting and analysis, software attached to the above measuring device was used.

(Polishing selectivity)
Using the polishing pads of Examples 1 and 2 and Comparative Example 1, polishing of the test pattern wafer for CMP evaluation was carried out under the following conditions. In the test pattern wafer for CMP evaluation, an oxide film (thickness: 100 Å) and a SiN stopper film (thickness: 1500 Å) are sequentially attached to a silicon wafer, and then a trench is formed, and a TEOS (TetraEthyl Orthosilicate) film is formed on the trench. (Thickness: 6000 Å) was formed, and the TEOS film was removed with a hard polishing pad until SiN was exposed. A portion where SiN is partially exposed is formed, thereby forming a pattern in which the widths of TEOS / SiN are 10 μm / 90 μm, respectively. The pattern surface composed of SiN and TEOS formed on the wafer was polished, and when 500 Å of SiN was removed, the polishing was completed and the step performance was evaluated. The step performance was evaluated by scanning the portion of the pattern after polishing with a contact-type step meter and calculating the dishing amount (R1), which is the amount of decrease in the TEOS thickness at the center of the trench portion. Dishing occurs because the SiN film, which is a stopper film existing at both ends of the separation region, is harder to polish than the TEOS film, so that the polishing pad is bent and the TEOS film in the separation region is polished. A phenomenon in which the center becomes thin. The larger the value of R1, the worse the dishing performance, and when R1 is 200 Å or less, it can be said that the dishing can be suppressed.
<Polishing conditions>
Polishing machine used: Ebara Corporation, product name "F-REX300"
Polishing speed (surface plate rotation speed): 70 rpm
Processing pressure: 176 g / cm ²
Slurry flow rate: 200 mL / min
Dresser: 3M diamond dresser, model number "A188"
Conditioning: Ex-situ, 30N, 4 scans Polishing time: Until SiN is polished by 500 Å Polished object: Pattern wafer with TEOS film / SiN film Polishing slurry: Made by Cabot Part number: SS-25 / 2-fold dilution (SS25 stock solution) : Pure water = 1: 1 mixture is used)

(Abrasive scratch)
For polishing scratches, the surface of the TEOS portion of the 10th, 20th, and 30th polishing treatments obtained by polishing in the above (polishing selectivity) is surface-inspected (manufactured by KLA Tencor, Surfscan SP2XP). ) Was measured in the high-sensitivity measurement mode, and the number (pieces) of polishing scratches of 90 nm or more in TEOS on the entire surface of the substrate was counted.
When the number of polishing scratches is 30 or less for the TEOS portion, it can be said that there are few polishing scratches and it is good.

The results are shown in Table 2 below and FIGS. 5 and 6. In addition, a cross-sectional photograph of the polishing pad obtained in Example 1 and Comparative Example 1 is shown in FIG.

From the results in Table 2, the content of the amorphous phase component at 40 ° C. with respect to the total of the content ratio of the interface phase component at 40 ° C. (Ai ₄₀ ) and the content ratio of the crystalline phase component at 40 ° C. (Ac ₄₀ ). ratio _{(Aa 40)} the ratio of _{(Aa 40 / (Ai 40 +} Ac 40)) is 2 to 10, the polishing pad of example 1 and 2 is the relaxation time of the components of the amorphous phase at 40 ° C. is 500~800μs It was found that the dishing amount (R1) was small and the polishing selectivity was excellent, and the relatively soft TEOS film could be prevented from being excessively scraped to suppress dishing and erosion.
Further, it was found that the polishing pads of Examples 1 and 2 can suppress the occurrence of polishing scratches on the TEOS portion. In the polishing pads of Examples 1 and 2, the ratio (Aa ₄₀ / Aa ₂₀ ) of the content ratio (Aa ₄₀ ) of the amorphous phase component at 40 ° C. to the content ratio (Aa ₂₀ ) of the amorphous phase component at 20 ° C. ) Is large, the amorphous component is relatively large at 40 ° C, which corresponds to the late polishing stage, and the molecular chain is not constrained and occupies most of the region where it is easy to move, and when dressed at about 20 ° C, amorphous It is considered that the occurrence of polishing scratches could be suppressed by improving the ease of tearing of the resin fat by reducing the components and making it easier to dress the polished surface.

On the other hand, although the relaxation time of the amorphous phase component at 40 ° C. is 500 to 800 μs, the polishing pad of Comparative Example 1 in which Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ ) is less than 2 is the polishing of Examples 1 and 2. Compared to the pad, R1 was large and inferior in dishing characteristics, and the TEOS portion also had many polishing scratches.

From the above results, the content ratio of the amorphous phase component at 40 ° C. to the total of the content ratio of the interface phase component at 40 ° C. (Ai ₄₀ ) and the content ratio of the crystalline phase component at 40 ° C. (Ac ₄₀ ). A polishing pad having a ratio of (Aa ₄₀ ) (Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ )) of 2 to 10 and an relaxation time of amorphous phase components at 40 ° C. of 500 to 800 μs suppresses dishing and erosion. It was also confirmed that the occurrence of polishing scratches could be further suppressed.

Further, according to the present invention, the component of the amorphous phase at 40 ° C. with respect to the total of the content ratio of the component of the interface phase at 40 ° C. (Ai ₄₀ ) and the content ratio of the component of the crystalline phase at 40 ° C. (Ac ₄₀ ). By confirming whether the ratio of the content ratio (Aa ₄₀ ) of (Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ )) is 2 to 10 and the relaxation time of the amorphous phase at 40 ° C. is 500 to 800 μs. It was found that the performance of the polishing pad such as the suppression of dishing and erosion and the suppression of the occurrence of polishing scratches can be evaluated.

Claims (6)

A polishing pad having a polishing layer containing a polyurethane resin.
In the polishing layer, the free induction decay signal (FID) obtained by pulse NMR is subtracted in order from the component having the longest spin-spin relaxation time T2 by the minimum square method, and the waveform is separated to obtain the longer spin-spin relaxation time T2. When divided into three components, amorphous phase, interfacial phase, and crystalline phase, in order from the beginning, the content ratio of the interfacial phase component at 40 ° C. (Ai ₄₀ ) and the content ratio of the crystalline phase component at 40 ° C. (Ac ₄₀ ). The ratio (Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ )) of the content ratio (Aa ₄₀ ) of the amorphous phase component at 40 ° C. is 2 to 10 and the relaxation time of the amorphous phase component at 40 ° C. The polishing pad having a value of 500 to 800 μs. Claim that the ratio (Aa ₄₀ / Aa ₂₀ ) of the content ratio (Aa ₄₀ ) of the amorphous phase component at 40 ° C. to the content ratio (Aa ₂₀ ) of the amorphous phase component at 20 ° C. is 1.5 to 3. Item 2. The polishing pad according to item 1. The method for manufacturing a polishing pad according to claim 1 or 2, wherein the method includes a step of using a wet film forming method. The method for polishing the surface of an optical material or a semiconductor material, which comprises the step of using the polishing pad according to claim 1 or 2. A method for evaluating a polishing pad having a polishing layer containing a polyurethane resin.
For the polishing layer, the free induction decay signal (FID) obtained by pulse NMR is subtracted in order from the component having the longest spin-spin relaxation time T2 by the minimum square method, and the waveform is separated to obtain the longer spin-spin relaxation time T2. When divided into three components, amorphous phase, interfacial phase, and crystalline phase, in order from the beginning, the content ratio of the component of the interfacial phase at 40 ° C. (Ai ₄₀ ) and the content ratio of the component of the crystalline phase at 40 ° C. (Ac ₄₀ ). The ratio of the content ratio (Aa ₄₀ ) of the amorphous phase component at 40 ° C. to the total of (Aa ₄₀ / (Ai ₄₀ + Ac ₄₀ )) is 2 to 10, and the relaxation time of the amorphous phase at 40 ° C. is 500. The evaluation method including a step of confirming whether or not it is ~ 800 μs. Whether or not the ratio (Aa ₄₀ / Aa ₂₀ ) of the content ratio (Aa ₄₀ ) of the amorphous phase component at 40 ° C. to the content ratio (Aa ₂₀ ) of the amorphous phase component at 20 ° C. is 1.5 to 3. The evaluation method according to claim 5, further comprising a step of confirming.