TWI833865B - Grinding composition - Google Patents

Abstract

The present invention provides a polishing composition that can further reduce minute defects and haze of polished semiconductor wafers. The polishing composition of the present invention contains 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 resin having the following general formula (B) Represents the polyoxyethylene structural unit of vinyl alcohol resin. Among them, 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. m is an integer from 1 to 1000.

Description

Grinding composition

The present invention relates to a polishing composition.

The polishing of semiconductor wafers using CMP (chemical mechanical polishing) is a three-stage or four-stage multi-stage polishing, thereby achieving high-precision smoothing and planarization. The main purpose of the final fine grinding step is to reduce minute defects or haze (surface blur).

The polishing composition used in the fine polishing step of semiconductor wafers usually contains water-soluble polymers such as hydroxyethyl cellulose (HEC). Water-soluble polymers have the function of making the surface of a semiconductor wafer hydrophilic, thereby inhibiting damage to the semiconductor wafer caused by adhesion of abrasive particles to the surface, excessive chemical etching, aggregation of abrasive particles, etc. This is known to reduce microscopic defects or haze.

HEC is made from cellulose, a natural raw material, and therefore may contain water-insoluble impurities derived from cellulose. Therefore, in polishing compositions containing HEC, minute defects may be generated due to the influence of this impurity. In addition, HEC mostly uses molecular weights of hundreds of thousands to millions. The higher the molecular weight, the easier it is to cause clogging of the pores of the filter. If the filter is a filter with a smaller pore size, it will be difficult for liquid to pass through. Therefore, when a water-soluble polymer with a relatively large molecular weight is used, it is difficult to remove coarse particles. In addition, agglomeration of abrasive particles is easily caused, so there are concerns about the long-term stability of the polishing composition.

Japanese Patent Application Laid-Open No. 2012-216723 discloses a polishing composition containing at least one water-soluble polymer selected from vinyl alcohol-based resins having a 1,2-diol structural unit.

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

Japanese Patent Application Laid-Open No. 2016-56220 discloses a slurry composition containing a water-soluble polymer in which a polyalkylene oxide structural unit and a polyvinyl alcohol structural unit form a main chain or side chain.

In recent years, as the design rules of semiconductor devices have been refined, more stringent management of minute defects or haze on the surface of semiconductor wafers has been required.

An object of the present invention is to provide a polishing composition that can further reduce minute defects and haze of polished semiconductor wafers.

A polishing composition according to one embodiment of the present invention contains abrasive grains, a basic compound, a vinyl alcohol resin having a 1,2-diol structural unit represented by the following general formula (A), and the following general formula ( B) Vinyl alcohol resin of the polyoxyethylene structural unit represented. [Chemical 1] Among them, 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. m is an integer from 1 to 1000.

According to the present invention, minute defects and haze of the polished semiconductor wafer can be further reduced.

The inventors of the present invention have conducted various studies in order to solve the above-mentioned problems. As a result, the following findings were obtained: By using a vinyl alcohol-based resin having a 1,2-diol structural unit in combination with a vinyl alcohol-based resin having a polyoxyethylene group in the side chain, micro defects and haze can be further reduced. . The mechanism is not clear, but it is believed that the adsorption properties of the two resins to the wafer are different. Therefore, it is believed that the two resins complement each other to reduce micro defects, thereby increasing the etching prevention effect or increasing the step elimination ability. It also reduces haze.

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

A polishing composition according to one 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 Vinyl alcohol resin with polyoxyethylene groups (hereinafter referred to as "PEG-added PVA").

The abrasive grains can be those commonly used in this field, for example, colloidal silica, fumed silica, colloidal alumina, fumed alumina, cerium oxide, etc., and colloidal silica or fumed silica is 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 the 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 diluted 10 to 40 times during polishing and used. The polishing composition of this embodiment is preferably diluted and used so that the concentration of the abrasive grains becomes 100 to 5000 ppm (mass ppm. The same applies below). The higher the concentration of abrasive particles, the more likely it is to reduce minute defects or haze. The lower limit of the concentration of the diluted abrasive particles is preferably 1000 ppm, and more preferably 2000 ppm. The upper limit of the concentration of the diluted abrasive grains is preferably 4000 ppm, and more preferably 3000 ppm.

Alkaline compounds react efficiently with the wafer surface and contribute to the polishing characteristics of chemical mechanical polishing (CMP). Examples of basic compounds include amine compounds, inorganic basic compounds, and the like.

Examples of amine compounds include primary amines, secondary amines, tertiary amines, quaternary ammonium and their hydroxides, heterocyclic amines, and the like. Specifically, ammonia, tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetrabutylammonium hydroxide (TBAH), methylamine, dimethylamine, trimethylamine, Ethylamine, diethylamine, triethylamine, hexylamine, cyclohexylamine, ethylenediamine, hexanediamine, diethylenetriamine (DETA), triethyltetramine, tetraethylenepentamine , Pentaethylenehexamine, monoethanolamine, diethanolamine, triethanolamine, N-(β-aminoethyl)ethanolamine, anhydrous piperazine, piperazine hexahydrate, 1-(2-aminoethyl)piperdine 𠯤, N-methyl piperazine, piperazine hydrochloride, guanidine carbonate, etc.

Examples of the inorganic alkaline compound include alkali metal hydroxides, alkali metal salts, alkaline earth metal hydroxides, alkaline earth metal salts, and the like. Specifically, the inorganic alkaline compound is potassium hydroxide, sodium hydroxide, potassium bicarbonate, potassium carbonate, sodium bicarbonate, sodium carbonate, etc.

One type of the above-mentioned basic compound may be used alone, or two or more types may be mixed and used. Among the above-mentioned alkaline compounds, alkali metal hydroxides, alkali metal salts, ammonia, amines, ammonium salts, and quaternary ammonium hydroxides are particularly preferred.

The content of the alkaline compound (the total amount when two or more are contained) is not particularly limited. For example, the mass ratio to the abrasive grain is the abrasive grain: alkaline compound = 1:0.001 to 1:0.10. The polishing composition of this embodiment is preferably diluted so that the concentration of the alkaline compound becomes 5 to 200 ppm before use.

Diol-modified PVA is a vinyl alcohol-based resin having a 1,2-diol structural unit represented by the following general formula (1). [Chemicalization 2] Among them, 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.

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

[Chemical 3]

In addition to the structural units represented by formulas (2) and (3), the glycol-modified PVA also has a 1,2-diol structural unit represented by formula (1). Thereby, the crystallization of polyvinyl alcohol is suppressed, which can further reduce minute defects or haze in the polished semiconductor wafer. 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%.

The diol-modified PVA is particularly preferably one in which R ¹ to R ⁶ in the 1,2-diol structural unit represented by the 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. [Chemical 4]

The average degree of polymerization of glycol-modified PVA is not particularly limited, but is, for example, 200 to 3,000. The average degree of polymerization of glycol-modified PVA can be measured according to JIS K 6726.

The preferred glycol-modified PVA has a saponification degree of 80 to 95 mol%. The polyvinyl alcohol-based resin used in polishing compositions is usually completely saponified (saponification degree is 98 mol% or more). However, in glycol-modified PVA, partially saponified products can be used to reduce the amount of saponified products compared to completely saponified products. Minor defects or haze. The mechanism is not clear, but one factor is thought to be that the use of partially saponified products reduces the hydrogen bonds between hydroxyl groups and weakens the bonds between molecules. This makes the polymer more easily soluble in water and inhibits the formation of undissolved matter or coagulation. The formation of gelatinous foreign matter. As another factor, it is considered that as the content of the vinyl acetate group as a hydrophobic group increases, the hydrophobic interaction with the semiconductor wafer becomes stronger and the protection of the semiconductor wafer becomes greater.

The saponification degree of glycol-modified PVA is preferably 85 to 90 mol%. In addition, the saponification degree of glycol-modified PVA is measured according to JIS K 6726 in the same manner as that of ordinary polyvinyl alcohol.

The content of glycol-modified PVA (the total amount when containing two or more) is not particularly limited. For example, the mass ratio of the glycol-modified PVA to the abrasive particles is: glycol-modified PVA=1:0.001~1: 0.40. The lower limit of the mass ratio of the glycol-modified PVA to the abrasive particles is preferably 0.004, and further preferably 0.008.

The polishing composition of this embodiment is preferably diluted and used so that the concentration of the glycol-modified PVA becomes 10 to 200 ppm. The higher the concentration of diol-modified PVA, the greater the tendency to reduce micro-defects or haze. The lower limit of the diluted modified PVA concentration is preferably 10 ppm, and 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).

[Chemistry 5] Among them, 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, 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 of this embodiment further contains PEG-added PVA in addition to the above-mentioned glycol-modified PVA. PEG-added PVA is a vinyl alcohol resin having a polyoxyethylene structural unit represented by the following general formula (6). In addition to the structural units represented by formulas (2) and (3), PEG-added PVA also has a polyoxyethylene structural unit represented by formula (6).

[Chemical 6] Among them, m is an integer from 1 to 1000.

By combining glycol-modified PVA with PEG-added PVA, micro defects and haze can be further reduced. The mechanism is not clear, but it is believed that the adsorption properties of the two resins to the wafer are different. Therefore, it is believed that the two resins complement each other to reduce micro defects, thereby increasing the etching prevention effect or increasing the step elimination ability. It also reduces haze.

The average degree of polymerization of PEG added PVA is not particularly limited, but is, for example, 200 to 3000. The average degree of polymerization of PEG added to PVA can be measured in accordance with JIS K 6726.

The abundance ratio of the polyoxyethylene skeleton and the polyvinyl alcohol skeleton in the PEG-added PVA is not limited to this. In molar %, for example, it is 5:95~40:60, preferably 10:90~30:70 . m is preferably 2 to 300, further preferably 3 to 200.

The content of PEG-added PVA (the total amount when containing two or more types) is not particularly limited. For example, the mass ratio of PEG-added PVA to abrasive grains is: PEG-added PVA = 1:0.001 to 1:0.40. The lower limit of the mass ratio of PEG-added PVA to the abrasive grains is preferably 0.004, and more preferably 0.008.

The polishing composition of this embodiment is preferably diluted so that the concentration of PEG-added PVA becomes 3 to 200 ppm. The higher the concentration of diluted PEG-added PVA, the more likely it is that minute defects or haze will be reduced. The lower limit of the diluted PEG-added PVA concentration is preferably 10 ppm, and more preferably 20 ppm.

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

The polishing composition of this embodiment may further contain a nonionic surfactant. By including nonionic surfactants, microscopic defects or haze can be further reduced.

Nonionic surfactants suitable for the polishing composition of this embodiment include, for example, ethylenediamine tetrapolyoxyethylene polyoxypropylene (Poloxamine), Poloxamer, polyoxyalkylene alkyl ether, and polyoxyalkylene fat. Acid ester, polyoxyalkylene alkylamine, polyoxyalkylene methyl glucoside, etc.

Examples of the polyoxyalkylene alkyl ether include polyoxyethylene lauryl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, and the like. 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 (the total amount when containing two or more types) is not particularly limited. For example, the mass ratio of the nonionic surfactant to the abrasive grains is: nonionic surfactant = 1:0.0001~ 1:0.015. The polishing composition of this embodiment is preferably diluted so that the concentration of the nonionic surfactant becomes 0.5 to 30 ppm.

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

In addition to the above, the polishing composition of this embodiment may also contain any complex agent generally known in the field of polishing compositions.

The polishing composition of this embodiment can be produced by appropriately mixing abrasive grains, alkaline compounds, glycol-modified PVA, PEG-added PVA and other compounding materials and adding water. Alternatively, the polishing composition of this embodiment can be produced by sequentially mixing abrasive grains, alkaline compounds, glycol-modified PVA, PEG-added PVA, and other compounding materials in water. As a method of mixing these components, methods commonly used in the technical field of polishing compositions such as homogenizers and ultrasonic waves can be used.

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

The polishing composition of this embodiment can be particularly preferably used for fine polishing of silicon wafers. [Example]

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

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

[Table 1] abrasive grains NH ₄ OH Diol modified PVA PEG plus PVA Other polymers Defect(s) Haze Content(ppm) Content(ppm) Kind Content(ppm) Content(ppm) Example 1 2300 20 A 20 3 - 2362 144 Example 2 2300 20 A 20 10 - 1130 134 Example 3 2300 20 A 20 20 - 615 134 Example 4 1100 20 A 20 3 - 1859 143 Example 5 1100 20 A 20 20 - 648 133 Example 6 2300 20 B 20 3 - 433 137 Example 7 2300 20 B 20 10 - 220 134 Example 8 2300 20 B 20 20 - 178 133 Example 9 1100 20 B 20 3 - 571 137 Example 10 1100 20 B 20 20 - 174 132 Example 11 1100 20 C 20 10 - 519 134 Comparative example 1 2300 20 A 20 - - 2454 152 Comparative example 2 1100 20 A 20 - - 2828 150 Comparative example 3 2300 20 B 20 - - 541 142 Comparative example 4 1100 20 B 20 - - 1215 144 Comparative example 5 1100 20 C 20 - - 776 141 Comparative example 6 1100 20 - - 20 - 3875 131 Comparative example 7 2300 20 A 40 - - 2067 151 Comparative example 8 1100 20 A 40 - - 1844 150 Comparative example 9 2300 20 - - 3 PVA: 20 ppm 5853 168 Comparative example 10 2300 20 - - 20 PVA: 20 ppm 2956 145 Comparative example 11 2300 20 - - 3 HEC: 20 ppm ＞50000 141 Comparative example 12 2300 20 - - 20 HEC: 20 ppm ＞50000 137 Comparative example 13 2300 20 A 20 - HEC: 3 ppm 5645 162 Comparative example 14 2300 20 A 20 - HEC: 20ppm 8304 161 Comparative example 15 2300 20 A 20 - PVP: 3ppm 3387 156

All contents in Table 1 are after dilution. The abrasive particles use colloidal silica with an average secondary particle size of 65 nm. "NH ₄ OH" means ammonia solution.

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

As the PEG-added PVA, polyvinyl alcohol (EF-05 manufactured by JAPAN VAM & POVAL Co., Ltd. manufactured by JAPAN VAM & POVAL) with 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 indicates polyvinyl alcohol with a polymerization degree of 500 and a saponification degree of 98.5 mol%. "HEC" means hydroxyethyl cellulose with a weight average molecular weight of 800,000. "PVP" means polyvinylpyrrolidone with a weight average molecular weight of 2500.

The polishing compositions of these examples and comparative examples were used to polish 12-inch silicon wafers. The conductivity type of silicon wafer is P type, and the resistivity used is above 0.1 Ωcm and less than 100 Ωcm. The polishing surface is set as the <100> surface. The grinding device uses the SPP800S single-sided grinding device manufactured by Okamoto Machinery Manufacturing Co., Ltd. Use suede pads as polishing pads. The polishing composition was diluted 31 times and supplied at a supply rate of 1 L/min. Set the rotation speed of the platen to 40 rpm, the rotation speed of the carrier to 39 rpm, and the grinding load to 100 gf/cm ² , and grind for 2 minutes. Furthermore, before polishing with the polishing compositions of Examples and Comparative Examples, polishing slurry Nanopure (registered trademark) NP7050S (manufactured by Nittahaas Co., Ltd.) was used to perform pre-polishing for 3 minutes.

Determine the micro-defects and haze of polished silicon wafers. Microdefects were measured using a wafer surface inspection device MAGICS M5640 (manufactured by Lasertec Corporation). The haze was measured using a wafer surface inspection device LS6600 (manufactured by Hitachi Engineering Co., Ltd.). The results are shown in the "Defects" and "Haze" columns of Table 1 mentioned above.

Figures 1 to 5 are graphs comparing grinding properties by changing the content of PEG added to 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 glycol-modified PVA is fixed at "A", and the content of glycol-modified PVA is fixed at 2300 ppm. Fixed at 20 ppm, the content of PEG added to PVA was changed to no addition (Comparative Example 1), 3 ppm (Example 1), 10 ppm (Example 2), and 20 ppm (Example 3) to compare the grinding characteristics. chart.

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 glycol-modified PVA is fixed at "A", and the content of glycol-modified PVA is fixed at 20 ppm. , a graph comparing the grinding properties by changing the content of PEG-added PVA to no addition (Comparative Example 2), 3 ppm (Example 4), and 20 ppm (Example 5).

In Figure 3, the abrasive grain content is fixed at 2300 ppm, the NH ₄ OH content is fixed at 20 ppm, the type of glycol-modified PVA is fixed at "B", and the glycol-modified PVA content is fixed at 20 ppm. , a graph comparing the polishing properties by changing the content of PEG-added PVA to no addition (Comparative Example 3), 3 ppm (Example 6), 10 ppm (Example 7), and 20 ppm (Example 8).

In Figure 4, the abrasive grain content is fixed at 1100 ppm, the NH ₄ OH content is fixed at 20 ppm, the type of glycol-modified PVA is fixed at "B", and the glycol-modified PVA content is fixed at 20 ppm. , a graph comparing the polishing properties by changing the content of PEG-added PVA to no addition (Comparative Example 4), 3 ppm (Example 9), and 20 ppm (Example 10).

In Figure 5, the content of abrasive grains is fixed at 1100 ppm, the content of NH ₄ OH is fixed at 20 ppm, the type of glycol-modified PVA is fixed at "C", and the content of glycol-modified PVA is fixed at 20 ppm. , a graph comparing the grinding properties by changing the content of PEG-added PVA to no addition (Comparative Example 5) and 10 ppm (Example 11).

According to Figures 1 to 5, it can be seen that in any of the glycol-modified PVA used this time, micro defects and haze can be further reduced by using it in combination with PEG-added PVA. In addition, from Figures 1 to 4, it can be seen that the greater the content of PEG-added PVA, the more minute defects and haze tend to be reduced.

Figure 6 is a graph comparing grinding characteristics by changing the type of glycol-modified PVA. Specifically, the glycol-modified PVA was changed to none (Comparative Example 6), "A" was changed to 20 ppm (Example 5), "B" was changed to 20 ppm (Example 10), and " Graph showing the comparison of polishing characteristics when C″ was changed to 20 ppm (Example 11). Furthermore, only the content of PEG-added PVA in the glycol-modified PVA "C" (Example 11) was set to 10 ppm, and the content of other PEG-added PVA was set to 20 ppm.

It can also be seen from Figure 6 that by using glycol-modified PVA and PEG-added PVA together, micro defects and haze can be further reduced. In addition, among the glycol-modified PVA used this time, "B" and "C" with lower saponification degree have better grinding properties than "A".

FIG. 7 is a graph comparing polishing characteristics while changing the components contained in the polishing composition while keeping the total amount of polymers in the polishing composition constant. Specifically, the polishing characteristics of a polishing composition containing only 40 ppm of glycol-modified PVA (Comparative Examples 7 and 8) were compared with those of a polishing composition containing 20 ppm of glycol-modified PVA and PEG-added PVA. Graph comparing the grinding characteristics of the compositions (Example 3 and Example 5). It can also be seen from Figure 7 that by using glycol-modified PVA and PEG-added PVA together, micro defects and haze can be further reduced.

Figure 8 shows the polishing characteristics of polishing compositions using glycol-modified PVA (Examples 3 and 8) and polishing compositions using ordinary PVA other than glycol-modified PVA (Comparative Example 10). Chart comparing grinding properties. As can be seen from Figure 8, the improvement of grinding characteristics by using it in combination with PEG-added PVA is a unique effect of glycol-modified PVA, but the same effect cannot be obtained with ordinary PVA.

Moreover, although not shown in the figure, in the polishing composition (Comparative Example 11 and Comparative Example 12) in which PEG was added to PVA and HEC was used in combination, the number of minute defects exceeded the detection limit and increased. It can also be seen from this that improving the polishing performance by using it in combination with PEG-added PVA is a unique effect of glycol-modified PVA.

Figure 9 is a graph comparing the polishing characteristics of polishing compositions using a polymer other than glycol-modified PVA and PEG-added PVA. Specifically, a polishing composition using only glycol-modified PVA (Comparative Example 1), a polishing composition containing 3 ppm of HEC added to glycol-modified PVA (Comparative Example 13), and glycol-modified PVA. A graph comparing the polishing characteristics of a polishing composition containing 20 ppm HEC in PVA (Comparative Example 14) and a polishing composition containing 3 ppm PVP in glycol-modified PVA (Comparative Example 15). It is found that when a polymer other than PEG-addition PVA is added to the glycol-modified PVA, the polishing characteristics worsen.

[Polishing Example 2] Polishing compositions of Examples 12 and 13 and Comparative Examples 16 and 17 shown in Table 2 were produced. The contents in Table 2 are all after dilution. In Grinding Example 2, in addition to the components shown in Table 2, as a nonionic surfactant, diluted ethylenediamine tetrapolyoxyethylene polyoxyethylene with a weight average molecular weight of 7240 was included in the contents of 2.9 ppm and 2.4 ppm respectively. Propylene, and polyoxypropylene methyl glucoside with a weight average molecular weight of 775. The abrasive grains, NH ₄ OH, glycol-modified PVA, and PEG-added PVA are the same as those in Polishing Example 1.

[Table 2] Silicon dioxide NH ₄ OH Diol modified PVA PEG plus PVA Defect(s) Haze Content(ppm) Content(ppm) Kind Content(ppm) Content(ppm) Example 12 1100 20 A 20 20 70 130 Example 13 1100 20 C 20 10 77 127 Comparative example 16 1100 20 A 20 - 149 129 Comparative example 17 1100 20 C 20 - 126 127

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

Comparison with Polishing Example 1 shows that minute 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 glycol-modified PVA is fixed at "A", and the content of glycol-modified PVA is fixed at 20 ppm. , changing the content of PEG-added PVA to no addition (Comparative Example 16) and 20 ppm (Example 12) to compare the polishing characteristics.

In Figure 11, the content of abrasive grains is fixed at 1100 ppm, the content of NH ₄ OH is fixed at 20 ppm, the type of glycol-modified PVA is fixed at "C", and the content of glycol-modified PVA is fixed at 20 ppm. , a graph showing the comparison of grinding characteristics by changing the content of PEG-added PVA to no addition (Comparative Example 17) and 10 ppm (Example 13).

It can be seen from Figures 10 and 11 that the polishing properties can be improved by using a combination of glycol-modified PVA and PEG-added PVA in a polishing composition containing a nonionic surfactant. Specifically, it is possible to further reduce minute defects while maintaining haze at a good level.

The embodiments of the present invention have been described above. The above-described embodiments are merely examples for implementing the present invention. Therefore, the present invention is not limited to the above-described embodiments, and the above-described embodiments can be appropriately modified and implemented within the scope that does not deviate from the gist of the invention.

Figure 1 is a graph comparing grinding properties by changing the content of PEG added to PVA. Figure 2 is a graph comparing grinding characteristics by changing the content of PEG added to PVA. Figure 3 is a graph comparing grinding characteristics by changing the content of PEG added to PVA. Figure 4 is a graph comparing grinding characteristics by changing the content of PEG added to PVA. Figure 5 is a graph comparing grinding characteristics by changing the content of PEG added to PVA. Figure 6 is a graph comparing grinding characteristics by changing the type of glycol-modified PVA. FIG. 7 is a graph comparing polishing characteristics while changing the components contained in the polishing composition while keeping the total amount of polymers in the polishing composition constant. FIG. 8 is a graph comparing the polishing characteristics of a polishing composition using glycol-modified PVA with the polishing characteristics of a polishing composition using ordinary PVA other than glycol-modified PVA. Figure 9 is a graph comparing the polishing characteristics of polishing compositions using a polymer other than glycol-modified PVA and PEG-added PVA. Figure 10 is a graph comparing grinding characteristics by changing the content of PEG added to PVA. Figure 11 is a graph comparing grinding properties by changing the content of PEG added to PVA.

Claims (3)

A polishing composition comprising: 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 resin having the following general formula (B) The polyoxyethylene structural unit represented by the vinyl alcohol resin,

Among them, 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; m It is an integer between 1 and 1000. The polishing composition of claim 1, further comprising a nonionic surfactant. The polishing composition of claim 1 or 2, wherein the above-mentioned basic compound is selected from the group consisting of alkali gold It is one or more of the group consisting of hydroxides, alkali metal salts, ammonia, amines, ammonium salts, and quaternary ammonium hydroxides.