JP7061969B2 - Polishing composition and polishing method - Google Patents

Description

The present invention relates to a polishing composition and a polishing method.

Polishing of semiconductor wafers by CMP realizes high-precision smoothing and flattening by performing three-step or four-step polishing. The main purpose of the finish polishing process, which is performed in the final stage, is to reduce haze (surface fogging) and minute defects.

The polishing composition used in the finish polishing step of a semiconductor wafer generally contains a water-soluble polymer such as hydroxyethyl cellulose (HEC). The water-soluble polymer has a role of making the surface of the semiconductor wafer hydrophilic, and suppresses damage to the semiconductor wafer due to adhesion of abrasive grains to the surface, excessive chemical etching, aggregation of abrasive grains, and the like. It is known that this can reduce haze and minute defects.

Since HEC is made from cellulose, which is a natural raw material, it may contain water-insoluble impurities derived from cellulose. Therefore, in the polishing composition containing HEC, minute defects may occur due to the influence of this impurity.

HECs with a molecular weight of several hundred thousand to one million are often used. The higher the molecular weight, the more likely the filter is to be clogged, and the smaller the pore size, the more difficult it is to pass the liquid. Therefore, when a water-soluble polymer having a large molecular weight is used, it becomes difficult to remove coarse particles. In addition, since agglomeration of abrasive grains is likely to occur, there is a concern about the long-term stability of the polishing composition.

Japanese Unexamined Patent Publication No. 2015-109423 describes a composition for polishing a silicon wafer containing 0.01 to 0.5% by mass of silica particles, a nitrogen-containing basic compound, and a water-soluble polymer. The water-soluble polymer of this polishing composition has a ratio of the number of oxygen atoms derived from the hydroxyl group to the number of oxygen atoms derived from the polyoxyalkylene of 0.8 to 10.

In recent years, with the progress of miniaturization of design rules for semiconductor devices, stricter control is required even for minute defects on the surface of semiconductor wafers.

An object of the present invention is to provide a polishing composition and a polishing method capable of further reducing minute defects and haze of a wafer after polishing.

The polishing composition according to one embodiment of the present invention contains silica particles, a basic compound, and polyglycerin, and the mass ratio of the silica particles to the polyglycerin is 0.9 or less.

In the polishing composition according to one embodiment of the present invention, the basic compound is at least selected from alkali metal hydroxides, alkali metal salts, ammonia, amines, ammonium salts, and quaternary ammonium hydroxides. It may be a kind.

The polishing composition according to one embodiment of the present invention preferably further contains a polyhydric alcohol which is a nonionic surfactant.

In the polishing composition according to one embodiment of the present invention, the polyhydric alcohol is preferably a multi-chain polyoxyalkylene alkyl ether.

In the polishing composition according to one embodiment of the present invention, it is preferable that the multi-chain polyoxyalkylene alkyl ether is at least one selected from polyoxyalkylene methylglucoside and polyoxyalkylene polyglyceryl ether.

The polishing method according to one embodiment of the present invention includes a step of finishing polishing a silicon wafer using the above-mentioned polishing composition and a urethane foam pad having a hardness of 80 or less.

According to the present invention, it is possible to further reduce minute defects and haze of the wafer after polishing.

The present inventors have conducted various studies in order to solve the above-mentioned problems. As a result, the following findings were obtained.

By using polyglycerin as the water-soluble polymer and setting the mass ratio of the silica particles to polyglycerin to 0.9 or less, the affinity between the dispersion medium and the surface of the silica particles is improved, and the dispersion medium and the silica particles are used. It becomes easy to get used to. As a result, the wafer is softly polished, scratches caused by particles are suppressed, and surface defects are reduced.

Furthermore, by adding a polyhydric alcohol, which is a nonionic surfactant, to polyglycerin, the dispersion medium becomes more compatible with the wafer. This enhances the protection of the wafer, further reduces surface defects, and realizes a smooth surface.

Polyglycerin usually has a lower molecular weight than HEC. Therefore, if polyglycerin is used as the water-soluble polymer, it seems that the silica particles are less likely to aggregate. However, as a result of the investigation by the present inventors, it was found that when polyglycerin is used as the water-soluble polymer, the silica particles are more likely to aggregate. The reason for this is considered as follows.

When the water-soluble polymer is HEC, some molecules have a three-dimensional network structure, so that a cluster incorporating silica particles is formed. Therefore, even if the concentration of silica particles is high, aggregation is unlikely to occur. On the other hand, in the case of polyglycerin, since clusters such as HEC are not formed, the concentration of silica particles is increased and the distance between particles is shortened. As a result, polyglycerin is adsorbed on the silica particles, and it becomes easy to condense. In addition, polyglycerin has a smaller molecular weight than HEC, and the number of molecules increases at the same concentration ratio. Therefore, the number of adsorbed molecules is also higher than that of HEC.

By setting the mass ratio of the silica particles to polyglycerin to 0.9 or less, aggregation of the silica particles can be suppressed. This can improve the long-term stability of the polishing composition.

Finish polishing of a silicon wafer is usually performed using a suede type polishing pad. However, in the above polishing composition, haze can be further reduced by polishing using a urethane foam type polishing pad.

The present invention has been completed based on these findings. Hereinafter, the polishing composition according to one embodiment of the present invention will be described in detail.

The polishing composition according to one embodiment of the present invention contains silica particles, a basic compound, and polyglycerin, and the mass ratio of the silica particles to polyglycerin is 0.9 or less.

The silica particles are blended into the polishing composition as abrasive particles. As the silica particles, those commonly used in this field can be used, and for example, colloidal silica, fumed silica and the like can be used.

The content of the silica particles is not particularly limited, but is, for example, less than 3% by mass of the entire polishing composition (stock solution). The upper limit of the content of the silica particles is preferably 1% by mass, more preferably 0.5% by mass, still more preferably 0.25% by mass. The lower limit of the content of the silica particles is preferably 0.015% by mass, more preferably 0.075% by mass.

The basic compound etches the surface of the wafer and chemically polishes it. The basic compound is, for example, an amine compound, an inorganic alkaline compound, or the like.

The amine compound is, for example, a primary amine, a secondary amine, a tertiary amine, a quaternary ammonium and a hydroxide thereof, a heterocyclic amine and the like. Specifically, ammonia, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrabutylammonium hydroxide (TBAH), methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, hexylamine, Cyclohexylamine, ethylenediamine, hexamethylenediamine, diethylenetriamine (DETA), triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, monoethanolamine, diethanolamine, triethanolamine, N- (β-aminoethyl) ethanolamine, anhydrous piperazine , Piperazine hexahydrate, 1- (2-aminoethyl) piperazine, N-methylpiperazine, piperazine hydrochloride, guanidine carbonate and the like.

Examples of the inorganic alkali compound include alkali metal hydroxides, alkali metal salts, alkaline earth metal hydroxides, alkaline earth metal salts and the like. Specific examples of the inorganic alkaline compound include potassium hydroxide, sodium hydroxide, potassium hydrogencarbonate, potassium carbonate, sodium hydrogencarbonate, and sodium carbonate.

The above-mentioned basic compounds may be used alone or in combination of two or more. Among the above-mentioned basic compounds, alkali metal hydroxides, alkali metal salts, ammonia, amines, ammonium salts, and quaternary ammonium hydroxides are preferable. The total content of the basic compound is not particularly limited, but is, for example, 0.0003 to 1.2% by mass of the total polishing composition (stock solution). The lower limit of the content of the basic compound is preferably 0.003% by weight. The upper limit of the content of the basic compound is preferably 0.6% by mass.

The polishing composition according to this embodiment contains polyglycerin as a water-soluble polymer. Polyglycerin forms a dispersion medium together with a basic compound and is adsorbed on the surface of silica particles and the surface of a wafer. By adsorbing the dispersion medium on the surface of the silica particles, polishing by the silica particles is softened and polishing scratches are suppressed. Further, the dispersion medium is adsorbed on the wafer surface, so that polishing scratches and adhesion of foreign matter are suppressed.

The structure of polyglycerin is not particularly limited, and examples thereof include a linear type, a branched type, and a dendrimer type. The weight average molecular weight of polyglycerin is not particularly limited, but is, for example, 100 to 20000. The lower limit of the weight average molecular weight of polyglycerin is preferably 300, more preferably 500. The upper limit of the weight average molecular weight of polyglycerin is preferably 10,000, more preferably 5,000.

The content of polyglycerin is not particularly limited, but is, for example, 0.15 to 3% by mass of the entire polishing composition (stock solution). The lower limit of the content of polyglycerin is preferably 0.2% by mass, more preferably 0.3% by mass. The upper limit of the content of polyglycerin is preferably 2.5% by mass, more preferably 2.0% by mass.

The polishing composition according to this embodiment has a mass ratio of silica particles to polyglycerin (silica particle content / polyglycerin content) of 0.9 or less. By setting the mass ratio of the silica particles to polyglycerin to 0.9 or less, the affinity between the dispersion medium composed of polyglycerin and the basic compound and the surface of the silica particles is increased, and the dispersion medium and the silica particles are easily compatible with each other. Become. The upper limit of the mass ratio of the silica particles to polyglycerin is preferably 0.8, more preferably 0.7. The lower limit of the mass ratio of the silica particles to polyglycerin is preferably 0.005, more preferably 0.01.

The polishing composition according to the present embodiment may further contain a polyhydric alcohol which is a nonionic surfactant. The polyhydric alcohol, which is a nonionic surfactant, penetrates between the molecules of polyglycerin and is densely adsorbed on the silica particles and the surface of the wafer. This makes it easier for the dispersion medium to become familiar with the silica particles and the surface of the wafer. As a result, surface defects can be further reduced and a smooth surface can be realized.

The polyhydric alcohol (hereinafter, may be simply referred to as “polyhydric alcohol”) which is a nonionic surfactant is specifically N, N, N', N'-tetrakis polyoxyethylene poly. Examples thereof include oxypropylene / ethylenediamine (poloxamine), polyvinyl alcohol, polyalkylene glycol, polyoxyalkylene alkyl ether (linear type, multi-chain type), polyoxyalkylene fatty acid ester, polyoxyalkylene alkylamine and the like.

Specific examples of the polyalkylene glycol are polyethylene glycol, polypropylene glycol and the like. Specific examples of the linear polyoxyalkylene alkyl ether include polyoxyethylene polyoxypropylene glycol (poloxamer), polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, and polyoxyethylene stearyl ether. The multi-chain type polyoxyalkylene alkyl ether is specifically an alkylene oxide derivative of methylglucoside (polyoxyalkylene methyl glucoside), polyoxyalkylene glyceryl ether, polyoxyalkylene diglyceryl ether, polyoxyalkylene polyglyceryl ether, polyoxyalkylene penta. Elythritol ether, polyoxyalkylene trimethylolpropane, polyoxypropylene sorbit and the like. More specifically, polyoxyethylene methyl glucoside, polyoxypropylene methyl glucoside, polyoxyethylene glyceryl ether, polyoxypropylene glyceryl ether, polyoxyethylene polyoxypropylene glyceryl ether, polyoxyethylene diglyceryl ether, polyoxypropylene di. Glyceryl ether, polyoxyethylene polyglyceryl ether, polyoxypropylene polyglyceryl ether, polyoxyethylene polyoxypropylene pentaerythritol ether, polyoxyethylene polyoxypropylene trimethylolpropane, polyoxypropylene sorbit and the like. Specific examples of the polyoxyalkylene fatty acid ester include polyoxyethylene monolaurate and polyoxyethylene monostearate. Specific examples of the polyoxyalkylene alkylamine are polyoxyethylene laurylamine, polyoxyethylene oleylamine and the like. Among these compounds, a multi-chain polyoxyalkylene alkyl ether is preferable, and a polyoxyalkylene methylglucoside or a polyoxyalkylene polyglyceryl ether is particularly preferable.

The weight average molecular weight of the polyhydric alcohol is not particularly limited, but is, for example, 100 to 30,000. The lower limit of the weight average molecular weight of the polyhydric alcohol is preferably 200, more preferably 500. The upper limit of the weight average molecular weight of the polyhydric alcohol is preferably 10,000, more preferably 1000.

The content of the polyhydric alcohol is not particularly limited, but is, for example, 0.003 to 0.3% by mass of the entire polishing composition (stock solution). The lower limit of the content of the polyhydric alcohol is preferably 0.005% by mass, more preferably 0.015% by mass. The upper limit of the content of the polyhydric alcohol is preferably 0.25% by mass, more preferably 0.15% by mass.

The polishing composition according to this embodiment may further contain a pH adjuster. The pH of the polishing composition according to this embodiment is preferably 8.0 to 12.0.

In addition to the above, the polishing composition according to the present embodiment may optionally contain a compounding agent generally known in the field of polishing composition.

The polishing composition according to this embodiment is prepared by appropriately mixing silica particles, a basic compound, polyglycerin and other compounding materials, and adding water. The polishing composition according to this embodiment is also prepared by sequentially mixing silica particles, a basic compound, polyglycerin and other compounding materials with water. As a means for mixing these components, means commonly used in the technical field of polishing compositions such as homogenizers and ultrasonic waves are used.

The polishing composition described above is diluted with water to an appropriate concentration and then used for polishing a silicon wafer.

The polishing composition according to this embodiment can be particularly preferably used for finish polishing of a silicon wafer.

The polishing composition according to this embodiment is suitable for polishing using a low-hardness urethane foam type polishing pad. By using the polishing composition according to the present embodiment and a low-hardness urethane foam type polishing pad, a polymer coating film having an appropriate film thickness is formed, and a balance between wafer protection and defect removal is achieved. Can be kept. By setting the amount of scraping to match the film thickness, a well-balanced polishing action can be exhibited with low damage. Further, by lowering the concentration of silica particles, aggregation during polishing is suppressed, and defects can be reduced.

The hardness of the polishing pad is 80 or less in JIS-A standard hardness. When the hardness of the polishing pad exceeds 80, the contact area (contact area) between the wafer and the pad becomes small, which makes it difficult to remove defects. The upper limit of the hardness of the polishing pad is preferably 78, and more preferably 75. The lower limit of the hardness of the polishing pad is preferably 40, more preferably 50.

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

[Polishing example 1]
The polishing compositions of Examples 1 to 8 and Comparative Examples 1 to 4 shown in Table 1 were prepared.

In Table 1, the "particle size" of the "silica particles" represents the average secondary particle size of the silica particles. "NH ₄ OH" represents an aqueous ammonia solution. "PGL" represents polyglycerin having a weight average molecular weight of 3000. "HEC" represents hydroxyethyl cellulose having a weight average molecular weight of 800,000. As the polyhydric alcohol, polyoxypropylene methylene glucoside having a weight average molecular weight of 775 was used. The balance of each polishing composition is water.

The polishing composition of Example 1 contained 0.297% by mass of colloidal silica, 0.045% by mass of an aqueous ammonia solution, and 0.45% by mass of polyglycerin. The polishing compositions of Examples 2 to 4 have colloidal silica contents of 0.15% by mass, 0.075% by mass, and 0.030% by mass, respectively, based on the polishing composition of Example 1. It was done. The polishing compositions of Examples 5 to 8 are based on the polishing composition of Example 1, and further contain polyoxypropylene methylglucoside in an amount of 0.015% by mass, 0.045% by mass, and 0.060% by mass, respectively. And 0.075% by mass.

The polishing composition of Comparative Example 1 contained 10.5% by mass of colloidal silica, 0.39% by mass of an aqueous ammonia solution, and 0.36% by mass of hydroxyethyl cellulose. The polishing composition of Comparative Example 2 contained 0.204% by mass of colloidal silica, 0.009% by mass of an aqueous ammonia solution, and 0.339% by mass of hydroxyethyl cellulose.

The polishing composition of Comparative Example 3 contained 1.5% by mass of colloidal silica, 0.045% by mass of an aqueous ammonia solution, and 0.75% by mass of polyglycerin. The polishing composition of Comparative Example 4 contained 1.5% by mass of colloidal silica, 0.06% by mass of an aqueous ammonia solution, and 0.75% by mass of polyglycerin.

A 12-inch silicon wafer was polished using the polishing compositions of these Examples and Comparative Examples. The conductive type of the silicon wafer was P type, and the one having a resistivity of 0.1 Ωcm or more and less than 100 Ω cm was used. The polished surface was set to <100> surface. As the polishing device, an SPP800S single-sided polishing device manufactured by Okamoto Machine Tool Mfg. Co., Ltd. was used. As the polishing pad, a urethane foam type polishing pad having a hardness of 73 was used. The polishing composition was diluted 30-fold and fed at a feed rate of 0.6 L / min. The surface plate rotation speed was 40 rpm, the carrier rotation speed was 39 rpm, and the polishing load was 100 gf / cm ² , and polishing was performed for 4 minutes.

The minute defects and haze of the silicon wafer after polishing were measured. The minute defects were measured using a wafer surface inspection device MAGICS M5640 (manufactured by Lasertec). As the haze, a wafer surface inspection device LS6600 (manufactured by Hitachi Engineering Co., Ltd.) was used. The results are shown in Table 1 above.

As shown in Table 1, in Examples 1 to 8 in which polyglycerin was used as the water-soluble polymer and the mass ratio of the silica particles to the polyglycerin was 0.9 or less, it was compared with Comparative Examples 1 to 4. In each case, the number of minute defects was reduced. In particular, in Examples 5 to 8 containing a polyhydric alcohol, the number of minute defects was significantly reduced. In addition, in Examples 5 to 8 containing the polyhydric alcohol, the haze was also significantly improved.

On the other hand, from the comparison of Examples 1 to 4, in the range where the mass ratio of the silica particles to polyglycerin was 0.9 or less, no significant difference was observed in the number of minute defects even if the content of the silica particles was changed. ..

In order to investigate the relationship between the mass ratio of the silica particles to polyglycerin and the minute defects in more detail, the interface characteristics between the silica particles and the dispersion medium were evaluated by the pulse NMR described below.

The response to changes in the magnetic field differs between the dispersion medium molecules that are in contact with or adsorbed on the particle surface and the dispersion medium molecules in the dispersion medium bulk (dispersion medium molecules that are not in contact with the particle surface in a free state). Generally, the movement of liquid molecules adsorbed on the particle surface is restricted, but the liquid molecules in the bulk liquid can move freely. As a result, the NMR relaxation time of the liquid molecules adsorbed on the particle surface is shorter than the NMR relaxation time of the liquid molecules in the bulk liquid. The NMR relaxation time observed in the liquid in which the particles are dispersed is the average value of the two relaxation times reflecting the liquid volume concentration on the particle surface and the liquid volume concentration in the free state.

The reciprocal of the NMR relaxation time (time constant) observed in the polishing composition in which silica particles are dispersed is Rav, and the reciprocal of the NMR relaxation time (time constant) observed in the polishing composition before dispersing the particles is Rav. Let Rb be used, and Rsp = (Rav / Rb) -1 is calculated. Rsp is an index of the affinity between the dispersion medium and the particle surface, and if the total surface area of the particles is the same, it means that the larger the Rsp, the higher the affinity between the dispersion medium and the particle surface.

In this example, the relaxation time was measured using a pulse NMR apparatus Acorn area manufactured by Xigo nanotools. The measurement conditions were magnetic field: 0.3 T, measurement frequency: 13 MHz, measurement nucleus: ¹ H NMR, measurement method: CPMG pulse sequence method, sample volume: 1 ml, temperature: 25 ° C.

The relaxation time was measured for the polishing compositions of Examples 1 and 7 described above. Further, as Comparative Example 5, a polishing composition having a silica particle content of 3% by mass was prepared based on the polishing composition of Example 7, and the relaxation time was measured in the same manner. The results are shown in Table 2.

“Rb ^-1 ” in Table 2 is the relaxation time observed in the polishing composition (blank) before the silica particles were dispersed, and “Rav ^-1 ” is the polishing composition in which the silica particles were dispersed. The relaxation time observed in the object. The "volume fraction" is the volume fraction of the silica particles in the entire polishing composition, and was calculated from the content and density of the silica particles. "Affinity" is Rsp = (Rav / Rb) -1 divided by the volume fraction of silica particles. When comparing the affinity between samples with different particle concentrations, strictly speaking, the value obtained by dividing Rsp by the total surface area of the particles should be used as an index, but in this comparison, all silica particles having the same average particle size are used. Since it was used, the total surface area of the silica particles was assumed to be proportional to the volume fraction.

From the comparison between Example 7 and Comparative Example 5, it can be seen that the affinity was remarkably improved by setting the mass ratio of the silica particles to polyglycerin to 0.9 or less. From this result, it is considered that the reason why the minute defects were reduced by setting the mass ratio of the silica particles to polyglycerin to 0.9 or less is due to the improvement of the affinity between the silica particles and the dispersion medium. Further, from the comparison between Example 1 and Example 7, it can be seen that the affinity between the silica particles and the dispersion medium was further improved by containing the polyhydric alcohol.

From the above results, it was confirmed that surface defects can be reduced by using polyglycerin as the water-soluble polymer and setting the content of silica particles to less than 0.3% by mass.

Next, the number of coarse particles (the number of particles having a particle size of 0.5 μm or more) in the polishing composition was measured. For the measurement of the number of coarse particles, an AccuSizer FX Nano Dual manufactured by Particle Sigmaning System was used. The results are shown in Table 3.

As can be seen from the comparison between Example 7 and Comparative Example 5, the number of coarse particles was significantly reduced by setting the mass ratio of the silica particles to polyglycerin to 0.9 or less. From this result, it can be seen that the aggregation of silica particles can be suppressed by setting the mass ratio of the silica particles to polyglycerin to 0.9 or less.

[Polishing example 2]
The polishing compositions of Examples 1, 6, 7, 9 to 16 and Comparative Example 6 shown in Table 4 were prepared. In addition, in order to make it easier to compare with Polishing Example 1, those having the same composition were numbered with the same Example (Examples 1, 6 and 7).

The polishing composition of Example 9 is based on the polishing composition of Example 1 and has a colloidal silica content of 0.400% by mass. The polishing compositions of Examples 10 to 12 were based on the polishing composition of Example 1, and the content of polyglycerin was 0.75% by mass, 0.9% by mass, and 1.8% by mass, respectively. It is a thing. The polishing composition of Example 13 is obtained by adding a polyhydric alcohol (polyoxypropylene methylglucoside) to the polishing composition of Example 12. The polishing compositions of Examples 13 to 16 are obtained by adding different types of polyhydric alcohols (see the margin of Table 3) to the polishing compositions of Example 1.

The polishing composition of Comparative Example 6 is obtained by replacing the polyglycerin of the polishing composition of Example 1 with hydroxyethyl cellulose.

A 12-inch silicon wafer was polished using the polishing compositions of Examples and Comparative Examples shown in Table 4. Except for using a supreme type polishing pad (Supreme (registered trademark) RN-H manufactured by Nitta Haas Co., Ltd.) as the polishing pad, polishing was performed under the same conditions as in polishing example 1, and minute defects were observed in the same manner as in polishing example 1. And haze were measured. Further, the affinity and the number of coarse particles were measured in the same manner as in Polishing Example 1. The results are shown in Table 5.

From this result, it was confirmed that the surface defects can be reduced by using polyglycerin as the water-soluble polymer and setting the mass ratio of the silica particles to the polyglycerin to 0.9 or less.

Finish polishing of a silicon wafer is usually performed using a suede-type polishing pad as in polishing example 2. In the conventional polishing composition, it is preferable to use a suede type polishing pad rather than a urethane foam type pad. On the other hand, in the case of the polishing compositions of Examples 1, 6 and 7, when the polishing example 1 and the polishing example 2 are compared, the minute defects are about the same, but the haze is less in the polishing example 1. It has become. That is, in the case of the polishing composition according to the present embodiment, it was found that by polishing using a urethane foam type pad, the haze can be further reduced with the same or less minute defects.

The embodiment of the present invention has been described above. The embodiments described above are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and the above-described embodiment can be appropriately modified and implemented within a range that does not deviate from the gist thereof.

Claims (6)

With silica particles
Basic compounds and
Including polyglycerin,
A polishing composition in which the mass ratio of the silica particles to the polyglycerin is 0.9 or less. The polishing composition according to claim 1.
The basic compound is at least one selected from alkali metal hydroxides, alkali metal salts, ammonia, amines, ammonium salts, and quaternary ammonium hydroxides, a composition for polishing. The polishing composition according to claim 1 or 2.
A polishing composition further comprising a polyhydric alcohol, which is a nonionic surfactant. The polishing composition according to claim 3.
The polyhydric alcohol is a polyoxyalkylene alkyl ether of a multi-chain type, which is a composition for polishing. The polishing composition according to claim 4, wherein the multi-chain polyoxyalkylene alkyl ether is at least one selected from polyoxyalkylene methylglucoside and polyoxyalkylene polyglyceryl ether. A polishing method comprising a step of finish polishing a silicon wafer using the polishing composition according to any one of claims 1 to 5 and a urethane foam pad having a hardness of 80 or less.