JP7361467B2 - polishing composition - Google Patents

Description

The present invention relates to a polishing composition.

Polishing of semiconductor wafers by CMP achieves highly accurate smoothing and flattening by performing multi-stage polishing of three or four stages. The main purpose of the final polishing step is to reduce micro defects and haze (surface cloudiness).

Polishing compositions used in the final polishing process of semiconductor wafers generally contain a water-soluble polymer such as hydroxyethyl cellulose (HEC). The water-soluble polymer has the role of making the surface of the semiconductor wafer hydrophilic, thereby suppressing damage to the semiconductor wafer due to adhesion of abrasive grains to the surface, excessive chemical etching, aggregation of abrasive grains, etc. It is known that this can reduce micro defects and haze.

Since HEC is made from cellulose, a natural raw material, it may contain water-insoluble impurities derived from cellulose. Therefore, in a polishing composition containing HEC, minute defects may occur due to the influence of this impurity. Further, HEC with a molecular weight of several hundred thousand to one million is often used, but the higher the molecular weight, the more likely filter clogging occurs, and it becomes difficult to pass liquid through a filter with a small pore size. Therefore, when a water-soluble polymer with a large molecular weight is used, it becomes difficult to remove coarse particles. Furthermore, since agglomeration of abrasive grains is likely to occur, there is also concern about the long-term stability of the polishing composition.

JP-A-2012-216723 discloses a polishing composition containing at least one water-soluble polymer selected from vinyl alcohol resins having a 1,2-diol structural unit.

Japanese Patent No. 6245939 discloses a silicon wafer polishing liquid composition containing a modified polyvinyl alcohol polymer having a polyalkyleneoxy group in its side chain.

JP 2016-56220A discloses a slurry composition containing a water-soluble polymer in which a polyalkylene oxide structural unit and a polyvinyl alcohol structural unit form a trunk or a side chain.

JP2012-216723A Patent No. 6245939 JP2016-56220A

In recent years, as design rules for semiconductor devices have become increasingly finer, stricter control is also required for minute defects and haze on the surface of semiconductor wafers.

An object of the present invention is to provide a polishing composition that can further reduce microdefects and haze in semiconductor wafers after polishing.

但し、Ｒ^１、Ｒ^２、及びＲ^３はそれぞれ独立して水素原子又は有機基を示し、Ｘは単結合又は結合鎖を示し、Ｒ^４、Ｒ^５、及びＲ^６はそれぞれ独立して水素原子又は有機基を示す。ｍは１～１０００の整数である。 A polishing composition according to an embodiment of the present invention includes abrasive grains, a basic compound, a vinyl alcohol resin having a 1,2-diol structural unit represented by the following general formula (A), and a vinyl alcohol-based resin having a 1,2-diol structural unit represented by the following general formula (A). (B) includes a vinyl alcohol resin having a polyoxyethylene structural unit represented by (B).

However, R ¹ , R ² , and R ³ each independently represent a hydrogen atom or an organic group, X represents a single bond or a bonded chain, and R ⁴ , R ⁵ , and R ⁶ each independently represent a hydrogen atom. Or indicates an organic group. m is an integer from 1 to 1000.

According to the present invention, micro defects and haze in a semiconductor wafer after polishing can be further reduced.

FIG. 1 is a graph comparing polishing characteristics with varying contents of PEG-added PVA. FIG. 2 is a graph comparing polishing characteristics with varying contents of PEG-added PVA. FIG. 3 is a graph comparing polishing characteristics with varying contents of PEG-added PVA. FIG. 4 is a graph comparing polishing characteristics with varying contents of PEG-added PVA. FIG. 5 is a graph comparing polishing characteristics with varying contents of PEG-added PVA. FIG. 6 is a graph comparing the polishing properties of different types of diol-modified PVA. FIG. 7 is a graph comparing the polishing properties with the total amount of polymer in the polishing composition being kept constant and the breakdown thereof being changed. FIG. 8 is a graph comparing the polishing properties of a polishing composition using diol-modified PVA with the polishing properties of a polishing composition using ordinary PVA that is not diol-modified PVA. FIG. 9 is a graph comparing the polishing properties of polishing compositions using a combination of diol-modified PVA and a polymer other than PEG-added PVA. FIG. 10 is a graph comparing polishing characteristics with varying contents of PEG-added PVA. FIG. 11 is a graph comparing polishing characteristics with varying contents of PEG-added PVA.

The present inventors conducted various studies in order to solve the above problems. As a result, it was found that micro defects and haze can be further reduced by using a vinyl alcohol resin having a 1,2-diol structural unit and a vinyl alcohol resin having a polyoxyethylene group in the side chain. The mechanism is not clear, but it is thought that these two types of resin have different adsorption properties to the wafer, and their complementary action reduces micro defects, increases the etching prevention effect, and eliminates the step difference. It is thought that haze is also reduced by increasing the viscosity.

The present invention was completed based on this knowledge. Hereinafter, a polishing composition according to an embodiment of the present invention will be described in detail.

A polishing composition according to an embodiment of the present invention includes abrasive grains, a basic compound, a vinyl alcohol resin having a 1,2-diol structural unit (hereinafter referred to as "diol-modified PVA"), and a side chain. A vinyl alcohol resin having a polyoxyethylene group (hereinafter referred to as "PEG-added PVA").

As the abrasive grains, those commonly used in this field can be used, and examples thereof include colloidal silica, fumed silica, colloidal alumina, fumed alumina, and ceria, with colloidal silica or fumed silica being particularly preferred. The particle size of the abrasive grains is not particularly limited, but for example, those having a secondary average particle size of 30 to 100 nm can be used.

The content of abrasive grains is not particularly limited, but is, for example, 0.10 to 20% by mass of the entire polishing composition. The polishing composition is used after being diluted 10 to 40 times during polishing. The polishing composition according to the present embodiment is preferably used after being diluted so that the concentration of abrasive grains is 100 to 5000 ppm (mass ppm, the same applies hereinafter). As the concentration of abrasive grains increases, micro defects and haze tend to decrease. The lower limit of the abrasive grain concentration after dilution is preferably 1000 ppm, more preferably 2000 ppm. The upper limit of the abrasive grain concentration after dilution is preferably 4000 ppm, more preferably 3000 ppm.

Basic compounds react efficiently with the wafer surface and contribute to the polishing properties of chemical mechanical polishing (CMP). Examples of the basic compound include amine compounds and inorganic alkali compounds.

Examples of amine compounds include primary amines, secondary amines, tertiary amines, quaternary ammonium and its hydroxides, and heterocyclic amines. 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, and alkaline earth metal salts. Specifically, the inorganic alkali compound includes potassium hydroxide, sodium hydroxide, potassium hydrogen carbonate, potassium carbonate, sodium hydrogen carbonate, sodium carbonate, and the like.

The above-mentioned basic compounds may be used alone or in combination of two or more. Among the basic compounds mentioned above, alkali metal hydroxides, alkali metal salts, ammonia, amines, ammonium salts, and quaternary ammonium hydroxides are particularly preferred.

The content of the basic compound (if two or more types are contained, the total amount) is not particularly limited, but for example, the mass ratio with the abrasive grains, abrasive grains: basic compound = 1:0.001 to 1:0. .10. The polishing composition according to the present embodiment is preferably used after being diluted so that the concentration of the basic compound is 5 to 200 ppm.

但し、Ｒ^１、Ｒ^２、及びＲ^３はそれぞれ独立して水素原子又は有機基を示し、Ｘは単結合又は結合鎖を示し、Ｒ^４、Ｒ^５、及びＲ^６はそれぞれ独立して水素原子又は有機基を示す。 Diol-modified PVA is a vinyl alcohol resin having a 1,2-diol structural unit represented by the following general formula (1).

However, R ¹ , R ² , and R ³ each independently represent a hydrogen atom or an organic group, X represents a single bond or a bonded chain, and R ⁴ , R ⁵ , and R ⁶ each independently represent a hydrogen atom. Or indicates an organic group.

"Vinyl alcohol resin" refers to a water-soluble polymer containing structural units represented by the following formulas (2) and (3).

Diol-modified PVA has a 1,2-diol structural unit represented by formula (1) in addition to the structural units represented by formulas (2) and (3). Thereby, crystallization of polyvinyl alcohol is suppressed, and micro defects and haze in the semiconductor wafer after polishing can be further reduced. The amount of modification of the 1,2-diol structural unit in the polymer is not particularly limited, but is, for example, 1 to 20 mol%.

Particularly preferred diol-modified PVA is one in which R ¹ to R ⁶ in the 1,2-diol structural unit represented by general formula (1) are all hydrogen atoms, and X is a single bond. That is, those containing the structural unit of the following formula (4) are particularly preferred.

The average degree of polymerization of diol-modified PVA is, for example, 200 to 3,000, although it is not particularly limited. The average degree of polymerization of diol-modified PVA can be measured in accordance with JIS K 6726.

The diol-modified PVA preferably has a saponification degree of 80 to 95 mol%. The polyvinyl alcohol resin used in polishing compositions is usually a fully saponified product (with a degree of saponification of 98 mol% or more), but for diol-modified PVA, a partially saponified product is used rather than a completely saponified product. In this case, micro defects and haze can be further reduced. The mechanism is not clear, but one factor is that by using partially saponified products, the hydrogen bonds between hydroxyl groups are reduced, and the bonds between molecules are weakened, making it easier for the polymer to dissolve in water. It is thought that the formation of gel-like foreign substances is suppressed. Another factor is that as the content of vinyl acetate groups, which are hydrophobic groups, increases, the hydrophobic interaction with the semiconductor wafer becomes stronger, and the protection for the semiconductor wafer becomes greater.

The saponification degree of diol-modified PVA is more preferably 85 to 90 mol%. In addition, the degree of saponification of diol-modified PVA shall be measured according to JIS K 6726 in the same manner as normal polyvinyl alcohol.

The content of diol-modified PVA (if two or more types are included, the total amount) is not particularly limited, but for example, the mass ratio with abrasive grains: abrasive grains: diol-modified PVA = 1:0.001 to 1:0. It is .40. The lower limit of the mass ratio of diol-modified PVA to abrasive grains is preferably 0.004, more preferably 0.008.

The polishing composition according to the present embodiment is preferably used after being diluted so that the concentration of diol-modified PVA is 10 to 200 ppm. The higher the concentration of diol-modified PVA after dilution, the more micro defects and haze tend to be reduced. The lower limit of the concentration of modified PVA after dilution is preferably 10 ppm, more preferably 20 ppm.

Diol-modified PVA is produced, for example, by saponifying a copolymer of a vinyl ester monomer and a compound represented by the following general formula (5).

但し、Ｒ^１、Ｒ^２、及びＲ^３はそれぞれ独立して水素原子又は有機基を示し、Ｘは単結合又は結合鎖を示し、Ｒ^４、Ｒ^５、及びＲ^６はそれぞれ独立して水素原子又は有機基を示し、Ｒ^７、及びＲ^８はそれぞれ独立して水素原子又はＲ^９－ＣＯ－（Ｒ^９は炭素数１～４のアルキル基）を示す。

However, R ¹ , R ² , and R ³ each independently represent a hydrogen atom or an organic group, X represents a single bond or a bonded chain, and R ⁴ , R ⁵ , and R ⁶ each independently represent a hydrogen atom. or an organic group, and R ⁷ and R ⁸ each independently represent a hydrogen atom or R ⁹ -CO- (R ⁹ is an alkyl group having 1 to 4 carbon atoms).

The polishing composition according to the present embodiment further includes PEG-added PVA in addition to the diol-modified PVA described above. PEG-added PVA is a vinyl alcohol resin having a polyoxyethylene structural unit represented by the following general formula (6). PEG-added PVA has a polyoxyethylene structural unit represented by formula (6) in addition to the structural units represented by formulas (2) and (3).

但し、ｍは１～１０００の整数である。

However, m is an integer from 1 to 1000.

By using diol-modified PVA and PEG-added PVA in combination, micro defects and haze can be further reduced. The mechanism is not clear, but it is thought that these two types of resin have different adsorption properties to the wafer, and their complementary action reduces micro defects, increases the etching prevention effect, and eliminates the step difference. It is thought that haze is also reduced by increasing the viscosity.

The average degree of polymerization of the PEG-added PVA is, for example, 200 to 3,000, although it is not particularly limited. The average degree of polymerization of PEG-added PVA can be measured in accordance with JIS K 6726.

The abundance ratio of polyoxyethylene skeleton and polyvinyl alcohol skeleton in PEG-added PVA is, but not limited to, in terms of mol%, for example, 5:95 to 40:60, preferably 10:90 to 30:70. . m is preferably 2 to 300, more preferably 3 to 200.

The content of PEG-added PVA (if two or more types are included, the total amount) is not particularly limited, but for example, the mass ratio with abrasive grains: abrasive grains: PEG-added PVA = 1:0.001 to 1:0. It is .40. The lower limit of the mass ratio of PEG-added PVA to abrasive grains is preferably 0.004, more preferably 0.008.

The polishing composition according to the present embodiment is preferably used after being diluted so that the concentration of PEG-added PVA is 3 to 200 ppm. The higher the concentration of PEG-added PVA after dilution, the more micro defects and haze tend to be reduced. The lower limit of the concentration of PEG-added PVA after dilution is preferably 10 ppm, more preferably 20 ppm.

The lower limit of the ratio of the content of PEG-added PVA to the content of diol-modified PVA is preferably 3 parts by weight of PEG-added PVA for 20 parts by weight of diol-modified PVA, more preferably 1 part by weight of PEG-added PVA for 2 parts by weight of diol-modified PVA. parts, and more preferably 3 parts by weight of PEG-added PVA per 5 parts by weight of diol-modified PVA. The upper limit of the ratio of the content of PEG-added PVA to the content of diol-modified PVA is preferably 5 parts by mass of PEG-added PVA to 1 part by mass of diol-modified PVA, and more preferably 5 parts by mass of PEG-added PVA to 1 part by mass of diol-modified PVA. 2 parts by mass of PVA, more preferably 3 parts by mass of PEG-added PVA per 2 parts by mass of diol-modified PVA.

The polishing composition according to this embodiment may further contain a nonionic surfactant. By including a nonionic surfactant, micro defects and haze can be further reduced.

Nonionic surfactants suitable for the polishing composition according to the present embodiment include, for example, ethylenediaminetetrapolyoxyethylenepolyoxypropylene (poloxamine), poloxamer, polyoxyalkylene alkyl ether, polyoxyalkylene fatty acid ester, polyoxyalkylene alkyl These include amines, polyoxyalkylene methyl glucosides, and the like.

Examples of the polyoxyalkylene alkyl ether include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, and polyoxyethylene stearyl ether. Examples of the polyoxyalkylene fatty acid ester include polyoxyethylene monolaurate, polyoxyethylene monostearate, and the like. Examples of the polyoxyalkylene alkylamine include polyoxyethylene laurylamine, polyoxyethylene oleylamine, and the like. Examples of polyoxyalkylene methyl glucoside include polyoxyethylene methyl glucoside, polyoxypropylene methyl glucoside, and the like.

The content of the nonionic surfactant (if two or more types are included, the total amount) is not particularly limited, but for example, the mass ratio with the abrasive grains: abrasive grains: nonionic surfactant = 1:0 .0001 to 1:0.015. The polishing composition according to the present embodiment is preferably used after being diluted so that the concentration of the nonionic surfactant is 0.5 to 30 ppm.

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 additives generally known in the field of polishing compositions.

The polishing composition according to the present embodiment is prepared by appropriately mixing abrasive grains, a basic compound, diol-modified PVA, PEG-added PVA, and other compounding materials, and adding water. Alternatively, the polishing composition according to the present embodiment can be prepared by sequentially mixing abrasive grains, a basic compound, diol-modified PVA, PEG-added PVA, and other compounding materials in water. As means for mixing these components, means commonly used in the technical field of polishing compositions, such as a homogenizer and ultrasonic waves, are used.

The polishing composition described above is used for polishing semiconductor wafers after being diluted with water to an appropriate concentration.

The polishing composition according to this embodiment can be particularly suitably used for final polishing of silicon wafers.

Hereinafter, the present invention will be explained in more detail with reference to Examples. The invention is not limited to these examples.

[Polishing example 1]
Polishing compositions of Examples 1 to 11 and Comparative Examples 1 to 15 shown in Table 1 were prepared.

The contents in Table 1 are all contents after dilution. Colloidal silica having an average secondary particle diameter of 65 nm was used as the abrasive grain. "NH ₄ OH" represents ammonia aqueous solution.

Three types of diol-modified PVA were used. "A" in the "Type" column represents a butenediol vinyl alcohol polymer having a degree of polymerization of 450 and a degree of saponification of 99.0 mol% or more. "B" represents a butenediol vinyl alcohol polymer with a degree of polymerization: 450 and a degree of saponification: 86.0 mol%. "C" represents a butenediol vinyl alcohol polymer with a degree of polymerization: 300 and a degree of saponification: 89.0 mol%.

As the PEG-added PVA, polyethylene glycol-introduced polyvinyl alcohol (EF-05, manufactured by Nippon Acety Vinyl Poval Co., Ltd.) having a degree of polymerization of 500 and a degree of saponification of 98.5 mol % or more was used.

"PVA" in the "Other polymers" column represents polyvinyl alcohol with a degree of polymerization: 500 and a degree of saponification: 98.5 mol%. "HEC" represents hydroxyethylcellulose with a weight average molecular weight of 800,000. "PVP" represents polyvinylpyrrolidone with a weight average molecular weight of 2500.

A 12-inch silicon wafer was polished using the polishing compositions of these Examples and Comparative Examples. The conductivity type of the silicon wafer used was P type, and the resistivity was 0.1 Ωcm or more and less than 100 Ωcm. The polished surface was a <100> surface. As the polishing device, an SPP800S single-sided polishing device manufactured by Okamoto Machine Tool Works Co., Ltd. was used. A suede pad was used as the polishing pad. The polishing composition was diluted 31 times and supplied at a supply rate of 1 L/min. Polishing was performed for 2 minutes at a rotation speed of the surface plate of 40 rpm, a rotation speed of the carrier of 39 rpm, and a polishing load of 100 gf/cm ² . Note that before polishing with the polishing compositions of Examples and Comparative Examples, preliminary polishing was performed for 3 minutes using polishing slurry Nanopure (registered trademark) NP7050S (manufactured by Nitta Haas Co., Ltd.).

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

FIGS. 1 to 5 are graphs comparing polishing characteristics with varying contents of PEG-added PVA.

Specifically, in Figure 1, the content of abrasive grains is fixed at 2300 ppm, the content of NH ₄ OH is fixed at 20 ppm, the type of diol-modified PVA is "A", the content of diol-modified PVA is fixed at 20 ppm, and PEG addition It is a graph comparing polishing properties when the PVA content is changed to no additive (Comparative Example 1), 3 ppm (Example 1), 10 ppm (Example 2), and 20 ppm (Example 3).

In Figure 2, the content of abrasive grains is fixed at 1100 ppm, the content of NH ₄ OH is fixed at 20 ppm, the type of diol-modified PVA is "A", the content of diol-modified PVA is fixed at 20 ppm, and the content of PEG-added PVA is fixed at 20 ppm. It is a graph comparing the polishing properties of additive-free (Comparative Example 2), 3 ppm (Example 4), and 20 ppm (Example 5).

In Figure 3, the content of abrasive grains is fixed at 2300 ppm, the content of NH ₄ OH is 20 ppm, the type of diol-modified PVA is "B", the content of diol-modified PVA is fixed at 20 ppm, and the content of PEG-added PVA is fixed. It is a graph comparing the polishing properties of additive-free (Comparative Example 3), 3 ppm (Example 6), 10 ppm (Example 7), and 20 ppm (Example 8).

Figure 4 shows that the content of abrasive grains is fixed at 1100 ppm, the content of NH ₄ OH is 20 ppm, the type of diol-modified PVA is "B", the content of diol-modified PVA is fixed at 20 ppm, and the content of PEG-added PVA is It is a graph comparing the polishing properties of additive-free (Comparative Example 4), 3 ppm (Example 9), and 20 ppm (Example 10).

Figure 5 shows that the content of abrasive grains is fixed at 1100 ppm, the content of NH ₄ OH is 20 ppm, the type of diol-modified PVA is "C", the content of diol-modified PVA is fixed at 20 ppm, and the content of PEG-added PVA is fixed at 20 ppm. It is a graph comparing the polishing properties with no additive (Comparative Example 5) and with 10 ppm (Example 11).

From FIGS. 1 to 5, it can be seen that in any of the diol-modified PVAs used this time, micro defects and haze can be further reduced by using them together with PEG-added PVA. Furthermore, from FIGS. 1 to 4, it can be seen that the higher the content of PEG-added PVA, the more micro defects and haze tend to be reduced.

FIG. 6 is a graph comparing the polishing properties of different types of diol-modified PVA. Specifically, without diol-modified PVA (Comparative Example 6), "A" was changed to 20 ppm (Example 5), "B" was changed to 20 ppm (Example 10), and "C" was changed to 20 ppm (Example 11). It is a graph comparing polishing characteristics. In addition, the content of PEG-added PVA was set to 10 ppm only in the diol-modified PVA of "C" (Example 11), and the content of PEG-added PVA was set to 20 ppm in the others.

It can also be seen from FIG. 6 that micro defects and haze can be further reduced by using diol-modified PVA and PEG-added PVA in combination. Furthermore, among the diol-modified PVAs used this time, "B" and "C", which have a low degree of saponification, had better polishing properties than "A".

FIG. 7 is a graph comparing the polishing properties with the total amount of polymer in the polishing composition being kept constant and the breakdown thereof being changed. Specifically, the polishing properties of polishing compositions containing only diol-modified PVA at 40 ppm (Comparative Examples 7 and 8) and polishing compositions containing 20 ppm each of diol-modified PVA and PEG-added PVA ( It is a graph comparing the polishing characteristics of Example 3 and Example 5). It can also be seen from FIG. 7 that micro defects and haze can be further reduced by using diol-modified PVA and PEG-added PVA in combination.

Figure 8 shows the polishing properties of polishing compositions (Example 3 and Example 8) using diol-modified PVA and the polishing properties of a polishing composition (Comparative Example 10) using normal PVA, which is not diol-modified PVA. This is a graph comparing the characteristics. From FIG. 8, it can be seen that the improvement in polishing properties when used in combination with PEG-added PVA is an effect specific to diol-modified PVA, and that a similar effect cannot be obtained with ordinary PVA.

Further, although not shown, in the polishing compositions (Comparative Examples 11 and 12) that used PEG-added PVA and HEC in combination, the number of micro defects exceeded the detection limit. This also shows that the improvement in polishing performance when used in combination with PEG-added PVA is an effect unique to diol-modified PVA.

FIG. 9 is a graph comparing the polishing properties of polishing compositions using a combination of diol-modified PVA and a polymer other than PEG-added PVA. Specifically, a polishing composition using only diol-modified PVA (Comparative Example 1), a polishing composition using diol-modified PVA with 3 ppm of HEC added (Comparative Example 13), and a polishing composition using diol-modified PVA with 20 ppm of HEC added. It is a graph comparing the polishing properties of a polishing composition (Comparative Example 14) and a polishing composition in which 3 ppm of PVP is added to diol-modified PVA (Comparative Example 15). It can be seen that when a polymer other than PEG-added PVA is added to diol-modified PVA, the polishing properties are rather deteriorated.

[Polishing example 2]
Polishing compositions of Examples 12 and 13 and Comparative Examples 16 and 17 shown in Table 2 were prepared. The contents in Table 2 are also all contents after dilution. In polishing example 2, in addition to the components shown in Table 2, ethylenediaminetetrapolyoxyethylene polyoxypropylene with a weight average molecular weight of 7240 and polyoxypropylene methyl glucoside with a weight average molecular weight of 775 were diluted as nonionic surfactants. The latter contents were 2.9 ppm and 2.4 ppm, respectively. The abrasive grains, NH ₄ OH, diol-modified PVA, and PEG-added PVA are the same as in Polishing Example 1.

Using the polishing compositions of Examples 12 and 13 and Comparative Examples 16 and 17, silicon wafers were polished in the same manner as in Polishing Example 1, and micro defects and haze were measured. The results are shown in Table 2.

A comparison with Polishing Example 1 shows that micro defects and haze can be significantly reduced by containing a nonionic surfactant.

In Figure 10, the content of abrasive grains is fixed at 1100 ppm, the content of NH ₄ OH is fixed at 20 ppm, the type of diol-modified PVA is fixed at "A", the content of diol-modified PVA is fixed at 20 ppm, and the content of PEG-added PVA is fixed at 20 ppm. It is a graph comparing the polishing properties of additive-free (Comparative Example 16) and 20 ppm (Example 12).

Figure 11 shows that the content of abrasive grains is fixed at 1100 ppm, the content of NH ₄ OH is 20 ppm, the type of diol-modified PVA is fixed at "C", the content of diol-modified PVA is fixed at 20 ppm, and the content of PEG-added PVA is fixed at 20 ppm. It is a graph comparing the polishing properties of additive-free (Comparative Example 17) and 10 ppm (Example 13).

10 and 11 show that even in a polishing composition containing a nonionic surfactant, the polishing properties can be improved by using diol-modified PVA and PEG-added PVA together. Specifically, micro defects can be further reduced while maintaining haze at a good level.

The embodiments of the present invention have been described above. The embodiments described above are merely examples for implementing the present invention. Therefore, the present invention is not limited to the embodiments described above, and can be implemented by appropriately modifying the embodiments described above without departing from the spirit thereof.

Claims (3)

Abrasive grains and
a basic compound;
A vinyl alcohol resin having a 1,2-diol structural unit represented by the following general formula (A),
A vinyl alcohol resin having a polyoxyethylene structural unit represented by the following general formula (B) ,
The vinyl alcohol resin having the 1,2-diol structural unit has an average degree of polymerization of 200 to 3000 and a saponification degree of 80 mol% or more,
The content of the vinyl alcohol resin having the 1,2-diol structural unit with respect to the content of the abrasive grains is such that the mass ratio is such that the abrasive grain: the vinyl alcohol resin having the 1,2-diol structural unit = 1. :0.001 to 1:0.40,
The vinyl alcohol resin having a polyoxyethylene structural unit has an average degree of polymerization of 200 to 3000,
The content of the vinyl alcohol resin having the polyoxyethylene structural unit with respect to the content of the abrasive grains is a mass ratio of the abrasive grains: the vinyl alcohol resin having the polyoxyethylene structural unit = 1:0.001. ~1:0.40,
The ratio of the content of the vinyl alcohol resin having the polyoxyethylene structural unit to the content of the vinyl alcohol resin having the 1,2-diol structural unit is the vinyl alcohol resin having the 1,2-diol structural unit. A polishing composition comprising 3 parts by mass or more of a vinyl alcohol resin having the polyoxyethylene structural unit based on 20 parts by mass of the resin .

However, R ¹ , R ² , and R ³ each independently represent a hydrogen atom or an organic group, X represents a single bond or a bonded chain, and R ⁴ , R ⁵ , and R ⁶ each independently represent a hydrogen atom. Or indicates an organic group. m is an integer from 1 to 1000. The polishing composition according to claim 1,
A polishing composition further comprising a nonionic surfactant. The polishing composition according to claim 1 or 2,
The polishing composition wherein the basic compound is one or more selected from the group consisting of alkali metal hydroxides, alkali metal salts, ammonia, amines, ammonium salts, and quaternary ammonium hydroxides.

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