KR20110014486A - A manufacturing method of colloidal silica for chemical mechenical polishing - Google Patents

Abstract

PURPOSE: A producing method of colloidal silica sol is provided to secure the excellent mechanical and chemical polishing rate of the colloidal silica sol, and to improve the purity of the colloidal silica sol. CONSTITUTION: A producing method of colloidal silica sol comprises the following steps: diluting silica seed sol to distilled water(S10); adding silicon powder to the diluted solution for forming a first dispersion solution(S20); adding a weak basic catalyst, and reacting to make a second dispersion solution(S30); inserting a strong basic catalyst, and reacting to obtain a third dispersion solution(S40); and filtering the third dispersion solution(S50).

Description

 Method for producing colloidal silica sol for chemical and mechanical polishing {A MANUFACTURING METHOD OF COLLOIDAL SILICA FOR CHEMICAL MECHENICAL POLISHING}

The present invention relates to a method for producing silica sol, and more particularly, to a method for preparing silica sol for chemical and mechanical polishing.

Silica sol has been used for a long time as a functional additive in various fields and as a wafer or glass abrasive, and is also used as an abrasive for silicon oxide film, which is one kind of insulating film used in semiconductor manufacturing process. In addition, it is also widely used as an abrasive for metal films for wiring such as copper and aluminum.

Conventional silica sol production methods include acid decomposition, electrodialysis, peptizing, ion exchange, hydrolysis. The double hydrolysis method is very advantageous for controlling the impurity content to be extremely low or for increasing sphericity, but in the case of the hydrolysis method, silicon tetrachloride (SiCl ₄ ) or tetraethyllysulfate (TEOS) is used as a starting material. Therefore, there is a high manufacturing cost problem. The other method is mostly water glass (silicate) to prepare silica sol. In general, a method of preparing water glass is adding sodium carbonate (Na ₂ CO ₃ ) to pulverized mineral or sand and heating to high temperature. The water glass produced by this method includes various types of sodium silicate salts such as sodium metasilicate (Na ₂ SiO ₃ ), sodium orthosilicate (Na ₄ SiO ₄ ) and 2-sodium silicate salt (Na ₂ Si ₂ O ₅ ). 20wt% to 50wt% is contained. Potassium silicate salt is also used in the manufacture of water glass bar glass silicate may include a water glass containing 20wt% to 50wt%. Therefore, when preparing a silica sol using water glass, there is a limit in controlling the sodium cation (Na ⁺ ) content of the silica sol. In addition, an excessive amount of cationic metals, such as sodium cations, is included. Cationic metal, which is a component of a polished semiconductor substrate or water glass attached to an oxide film surface, causes problems such as poor insulation of a circuit, a short circuit, and a decrease in dielectric constant. . In particular, sodium has a small particle size, high diffusivity, and remains in fine scratches of the polished film, which may cause many of the above problems. This is the same as in the case of potassium silicate salts, which also includes many problems when using potassium silicate salts in semiconductor fabrication.

In addition, according to the conventional silica sol manufacturing method, since the silica sol must be prepared using the water glass after manufacturing the water glass, the manufacturing process is complicated, and the conventional manufacturing methods are deoxidized washing process or ion by acid reaction. After the exchange reaction is required to wash the ion exchange resin, there is a problem that a large amount of waste water occurs in this process.

In order to solve the above problems, a direct oxidation method for preparing silica sol directly from silicon using a strong base material as a catalyst has been proposed. This method eliminates the need for a separate cationic material removal process, and in particular, the conventional complex manufacturing process is simplified to save energy, prevent waste of treatment chemicals, eliminate waste water treatment problems, reduce manufacturing time, and reduce costs. There is.

In the conventional method for producing silica sol by the direct oxidation method, a monodisperse silica sol having a large particle size and a uniform and large specific surface area of silica may be prepared by adjusting the type of catalyst and the reaction time. This is a process that can control the silica particle diameter by adjusting the reaction time, but there is a problem that it is difficult to obtain a silica sol containing silica particles having high polishing rate and cohesive by this method.

Accordingly, an object of the present invention is to provide a method for preparing a chemical and mechanical polishing silica sol having uniform characteristics of silica particles having excellent uniformity of chemical and mechanical polishing rate because of uniformity of silica particles. It is done.

Method for producing a chemical and mechanical polishing colloidal silica sol of the present invention for achieving the above object is a step of diluting agglomeration mode silica seed sol in distilled water to form a dilution, silicon powder is added to the dilution to the first dispersion solution Preparing a second dispersion solution by adding a weakly basic catalyst to 0.5 parts by weight to 60 parts by weight based on 100 parts by weight of the silicon powder and reacting the first dispersion with a weak base catalyst. 0.5 to 10 parts by weight of a basic catalyst is added to 100 parts by weight of the silicon powder and reacted to prepare a third dispersion solution, and filtering the third dispersion solution.

The agglomeration mode silica seed sol may be any one selected from a seed sol, which is a dispersion of dry silica, an acid agglomerated silica sol seed sol, an alcohol agglomeration seed sol, and an agglomeration seed sol including methyl trimethoxy silane (MTMS). Can be. And the content includes 1 to 10 parts by weight relative to 100 parts by weight of the distilled water.

 The silicon powder is 5 parts by weight to 25 parts by weight with respect to 100 parts by weight of distilled water.

The second dispersion solution preparation step includes the reaction for 1 hour to 10 hours at 5 ℃ to 100 ℃.

The weakly basic catalyst is methyl amine, ethyl amine, n-propyl amine, n-butyl amine, dimethyl amine, diethyl Amine (dietyl amine), dipropyl amine, dibutyl amine, trimethyl amine, triethylamine, tripropyl amine, tributylamine amine) and ammonium hydroxide.

The preparing step of the third dispersion solution is a method for producing a silica sol, characterized in that made by reacting for 5 to 100 hours at 10 to 36 hours.

The strong base catalyst includes one selected from the group consisting of potassium hydroxide, barium hydroxide, cesium hydroxide and lithium hydroxide.

The particle size of the silicon powder includes 50 mesh to 1000 mesh and the content thereof is 95 wt% or more.

Chemical and mechanical polishing silica sol produced by any one of the above methods.

According to the method of preparing a colloidal silica sol for chemical and mechanical polishing by direct oxidation from the metal silicon according to the present invention, the size of the silica particles in the final silica sol is large and uniform, and has excellent chemical and mechanical polishing rates.

In addition, the silica sol manufacturing method of the present invention is a process for obtaining a high purity silica sol with an industrial silicon powder having a silicon content of 95% or more.

Hereinafter, a method of preparing a chemical and mechanical polishing colloidal silica sol according to the present invention will be described in detail with reference to the accompanying drawings.

For reference, the method may include preparing a dilute solution, preparing a first dispersion solution, preparing a second dispersion solution, preparing a third dispersion solution, and filtering a third dispersion solution.

1 is a flow chart sequentially showing a method for manufacturing a chemical and mechanical polishing colloidal silica sol according to an embodiment of the present invention.

 Referring to FIG. 1, in the method for preparing a chemical and mechanical polishing colloidal silica sol of the present invention, a silica seed sol in agglomerated mode is diluted with distilled water to form a dilution solution.

 The agglomeration mode silica seed sol added in the dilution solution production step is selected from agglomeration seed sol including a dry sol dispersed silica, acid agglomerated silica sol seed sol, alcohol agglomerated seed sol and methyltrimethoxysilane (MTMS) It is preferable.

The seed sol in which the dry silica was dispersed was prepared by using a 10 wt% dry silica slurry for 1 hour and centrifugation at 6,000 rpm for 1 hour using a dispersed phase of a supernatant (average particle diameter ˜100 nm). 2a and 2b are photographs of abrasive silica particles grown in seed sol in which dry silica is dispersed. 3A and 3B are particle size distributions of dry silica seed sol and abrasive silica particles grown with seed sol.

The acid-aggregated silica sol seed sol is prepared by putting nitric acid in 30 wt% 10 nm silica sol to lower the acidity and then re-dispersing by adding potassium hydroxide (KOH). Referring to Figure 4 is a photograph of the abrasive silica particles grown acid-aggregated silica sol as a seed.

The alcohol coagulant seed sol is prepared by mixing 30 wt% 10 nm silica sol and ethanol in a ratio of 6: 4. 5 is a photograph of abrasive silica particles in which alcohol-aggregated silica sol is grown as a seed in a direct oxidation process of silicon.

The aggregated seed sol including methyl trimethoxysilane (MTMS) is prepared by adding nitric acid to 90 g of 30 wt% 35 nm silica sol, then adding 3 g of methyl trimethoxy silane (MTMS) and stirring at room temperature for about 1 hour. Part of the reaction at the surface serves as a binder to help stabilize the aggregation. This causes an additional reaction and induces aggregation.

This is because the gelation rate is weak at low acidity and the coagulation is induced at the phase separation stability.

Next, silicon powder is added to the diluent to prepare a first dispersion solution (S20).

The amount of silicon powder added in the first dispersion solution production step is preferably 5 parts by weight to 25 parts by weight with respect to 100 parts by weight of the diluent. In addition, the amount of the silica seed sol is preferably 1 part by weight to 10 parts by weight with respect to 100 parts by weight of distilled water.

When the amount of silicon powder added is less than 5 parts by weight with respect to 100 parts by weight of distilled water, the concentration of silica sol is light and the yield is considerably decreased after the final reaction, and when it exceeds 25 parts by weight, the yield is high but the concentration is too thick. There is.

The particle size of the silicon powder is preferably 50 mesh (mesh) to 1000 mesh (mesh). When small particles having a particle size of less than 1000 mesh are used, the reaction rate is so fast that there is not enough time for the silica particles to grow in the silica sol, and the reaction is so intense that there is a risk of explosion. If the particle size exceeds 50 mesh (mesh), the reaction rate is slow, the time required for the entire reaction is too long, and the yield is also disadvantageous.

When the concentration of silica sol is high, the viscosity increases. In the case of high viscosity silica sol, the gel is finally gelled, and thus, low viscosity is evaluated as having high stability. In particular, securing stability is an important factor in terms of transportation of silica sol and user storage.

In the method for preparing silica sol of the present invention, silicon powder is used as a starting material, but in the method for preparing silica sol according to hydrolysis or condensation polymerization method, silicon tetrachloride (SiCl ₄ ) or saethylol silicon silicate (TEOS; tetraethly orthosilicate) is used as a starting material. ) Is used. Silica sol production method using the tetraethyl ethylene silicate (TEOS; tetraethly orthosilicate) and the like as a starting material has a disadvantage that the process is complicated and expensive manufacturing cost compared to the silica sol production method according to the present invention.

Next, a weakly basic primary catalyst is added to the first dispersion solution and reacted to prepare a second dispersion solution (S30).

The reaction process of preparing the second dispersion solution is performed by adding a weakly basic primary catalyst to the first dispersion solution and reacting it at 5 ° C. to 100 ° C. for 1 hour to 10 hours.

As described, since the silica sol tends to be gelated eventually when the concentration is high, it is very important in terms of stability to prepare a silica sol having a low viscosity. Viscosity tends to decrease as the size of the particles increases, so weak salts such as ammonium hydroxide and amines are used to prepare silica sol with large particles rather than strong base such as sodium hydroxide (NaOH). It is preferable to increase the reaction time after adding the primary catalyst and before adding the secondary catalyst.

Weakly basic substances used as primary catalysts are methyl amine, ethyl amine, n-propyl amine, n-butyl amine, dimethylamine (dimethyl amine, dityl amine, dipropyl amine, dibutyl amine, tributyl amine, trimethyl amine, trietyl amine, tripropyl amine ), Tributyl amine and ammonium hydroxide.

In the case of using a strong base such as sodium hydroxide as the primary catalyst, the reaction is very vigorous and proceeds rapidly, and the yield is high, but there is not enough time for the particles to grow sufficiently, so that the average particle diameter of the silica particles in the final silica sol exceeds 50 nm. Few. On the other hand, in the case of using a weakly basic catalyst such as ammonium hydroxide or amines, the reaction rate is slightly slow but there is an advantage that the particles can be sufficiently grown.

The amount of the weakly basic catalyst added in this step is preferably 0.5 parts by weight to 25 parts by weight based on 100 parts by weight of the silicon powder added in the step (S20).

When the amount of the catalyst is less than 0.5 parts by weight, the reaction hardly proceeds. When the amount of the catalyst is more than 60 parts by weight, the reaction rate increases, but the size of the silica particles in the silica sol is reduced due to the growth of the particles.

In the silica sol production method of the present invention, the smaller the amount of the first and second catalysts, the larger the reaction time after the addition of the first catalyst and before the addition of the second catalyst, the larger the size of the silica particles, the silica sol production method of the present invention By controlling the amount and reaction time of the silver catalyst there is an advantage that can control the size of the desired particles according to the application.

Next, a strong basic secondary catalyst is added to the second dispersion solution and reacted to prepare a third dispersion solution (S40).

The reaction process of the third dispersion solution preparation step is made by adding a strong base catalyst to the second dispersion solution and reacting it for 10 hours to 36 hours at 5 ℃ to 100 ℃.

The strong base catalyst used as the secondary catalyst is preferably sodium hydroxide, potassium hydroxide, barium hydroxide, cesium hydroxide and lithium hydroxide.

When using potassium hydroxide, barium hydroxide, cesium hydroxide and lithium hydroxide as the secondary catalyst, it is possible to prepare a very high purity silica sol by maintaining the concentration of sodium cation (Na ⁺ ) in the final silica sol less than 10ppm. Because sodium cation (Na ⁺ ) is small in particle size, it is highly diffused and remains in fine scratches of the polished film, causing many problems. Therefore, when sodium cation (Na ⁺ ) concentration in silica sol is high, it is used as an abrasive for semiconductor wafers. Not suitable for Therefore, it is important to prepare silica sol with low sodium cation (Na ⁺ ) concentration. When preparing this silica sol using potassium hydroxide, barium hydroxide, cesium hydroxide and cesium hydroxide, the concentration of sodium cation (Na ⁺ ) in the final silica sol Is influenced only by the purity of the silicon powder added initially, so if a high purity silicon powder is used, the sodium cation (Na ⁺ ) in the final silica sol By maintaining the concentration below 10ppm it is possible to obtain a high purity silica sol with less impurities.

The amount of the strong base catalyst added in the third dispersion solution preparation step is preferably 0.5 parts by weight to 25 parts by weight based on 100 parts by weight of the silicon powder added in the first dispersion solution preparation step.

If the secondary catalyst is added less than 0.5 parts by weight, the reaction does not proceed, if the amount exceeds 10 parts by weight, the yield of the final silica sol is increased, the particle size is small and the aggregation factor (aggregation factor) There was a tendency to increase.

Next, the third dispersion solution prepared through the above process is filtered (S50).

As a filtration method in the filtration step of the third dispersion solution, a press filter may be preferably used, but is not limited thereto. This step may be repeated several times as needed.

Through this step, as the unreacted material is removed, a final product, silica sol, can be obtained. Silica sol prepared through the silica sol manufacturing method according to the present invention has a high content of generally 30% or more without a concentration process. And it is possible to control the content of sodium cation (Na ⁺ ) to within a few ppm depending on the selection of the raw material.

The particle size of the silicon powder is preferably 50 mesh (mesh) to 1000 mesh (mesh) and the content of silicon is preferably 95% by weight or more.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the following description is presented to assist in understanding the present invention, but the present invention is not limited to the following description.

Example 1 Preparation of Silica Sol with Dry Silica Seed Sol

23.4 g of silicon powder (purity 97%, 325 mesh) was added to the seed sol (10.54 g of silica, 195 g of water) in which dry silica was dispersed, and stirred, and 5 ml of an aqueous 28% NH ₄ OH solution was added to the slurry. A dispersion solution was prepared by stirring at 100 ° C. for 1 hour, and 2.67 ml of 4N potassium hydroxide (KOH) was added to the dispersion solution, reacted at 100 ° C. for 18 hours, and filtered to prepare a silica sol. In this case, the seed sol in which the dry silica is dispersed is coated with a 10 wt% dry silica slurry for 1 hour, and centrifuged at 6,000 rpm for 1 hour to use a dispersed phase of a supernatant (average particle diameter of 100 nm).

Example 2 Preparation of Silica Sol with Acid Aggregated Seed Sol

23.4 g of silicon powder (purity 97%, 325 mesh) was added to 205.54 g (silica 10.54 g, water 195 g) of acid-aggregated silica sol seed sol, and the other conditions were the same as in Example 1. Agglomerated silica seed sol was added to 30 wt% 10 nm silica sol, dropped to pH 3, stirred at room temperature for 30 minutes, and gelled to redisperse by adding small amount of potassium hydroxide (KOH). Dilute with water to suit the amount of sol.

Example 3 Preparation of Silica Sol with Alcohol Coagulant Seed Sol

The alcohol coagulant seed sol is mixed with 30 wt% 10 nm silica sol and ethanol at a ratio of 6: 4, aged for 3 hours, and then diluted with water to suit the amount of seed sol to be prepared. Silica sol was prepared by adding 23.4 g of silicon powder (purity 97%, 325 mesh) to 195 g of alcohol-aggregated silica seed sol (5.85 g of silica), and the other conditions were the same as those of <Example 1>.

Example 4 Preparation of Silica Sol with Aggregated Seed Sol Containing Methyltrimethoxysilane (MTMS)

Aggregated seed sol containing methyl trimethoxysilane (MTMS) was added to 90 g of 30 wt% 35 nm silica sol, the pH was dropped to 5, and 3 g of methyl trimethoxysilane (MTMS) was added. Bass to prepare a seedsol. Agglomerated silica seed sol containing methyltrimethoxysilane (MTMS) is dispersed in 21 g of silicon powder (purity 97%, 200 mesh) and 120 g of water. 5 ml of 28% NH ₄ OH aqueous solution is added to this solution, and the temperature is raised to 100 ° C. After maintaining at 100 ° C. for 3 hours, 1.5 g of 95% potassium hydroxide (KOH) was added to the dispersion, reacted for 18 hours, and filtered to prepare a silica sol.

Comparative Example 1

After dispersing 34 g of silicon powder (97% purity, 325 mesh) in 195 g of distilled water, 5 ml of 28% NH ₄ OH aqueous solution was added thereto, and stirred at 100 ° C. for 1 hour to prepare a dispersion solution. 4N potassium hydroxide (KOH) 5.34ml was added to the dispersion solution, reacted at 100 ° C for 18 hours, and filtered to prepare silica sol.

Comparative Example 2

After dispersing 34 g of silicon powder (97% purity, 325 mesh) in 195 g of distilled water, 20 ml of 28% NH ₄ OH aqueous solution was added thereto, and the mixture was stirred at 100 ° C. for 1 hour to prepare a dispersion solution, followed by 4N potassium hydroxide (KOH). ) 2.67ml was added to the dispersion solution and reacted at 100 ° C. for 18 hours, followed by filtration to prepare silica sol.

Comparative Example 3

After dispersing 34 g of silicon powder (97% purity, 325 mesh) in 195 g of distilled water, 5 ml of 28% NH ₄ OH aqueous solution was added thereto, and stirred at 100 ° C. for 3 hours to prepare a dispersion solution. 4N potassium hydroxide (KOH) 2.67ml was added to the dispersion solution, reacted at 100 ° C for 18 hours, and filtered to prepare silica sol.

Experimental Example Evaluation of Polishing Rate

The polishing rate was evaluated using POLI-350 (G & P technology) equipment, and the polishing pad is K-Groove type with IC100 / Suba400 Stacked. Polishing conditions were 1 minute polishing at 600g / cm ² pressure, head (table) and table speed (table speed) 90rpm, slurry flow rate (slurry flow rate) 200ml / min. A film thickness measuring instrument (F50, FILMETRICS Co., Ltd.) was used to measure the thickness of the removed oxide film. The thickness of the polished oxide film on a 4-inch silicon wafer with an oxide film was determined. The average thickness was determined by measuring at the point, and the polishing rate (Å / min) was expressed by the difference in average oxide film thickness before and after polishing.

TABLE 1

                                                  Unit: nm

No Size 1 (Mass Size Analyzer: PSA) Size 2 (Transmission electron microscope: TEM) Cohesion Polishing rate (Å / min) Example 1 145 50 2.9 559 Example 2 107 50 2.1 311 Example 3 107 40 2.7 329 Example 4 85 42 2.0 324 Comparative Example 1 45 40 1.1 92 Comparative Example 2 71 60 1.2 177 Comparative Example 3 113 100 1.1 220

[Table 1] measured the size and agglomeration of the silicon particles in the silica sol with a light scattering photometer (Size 1) and transmission electron microscope (TEM) (Size 2) for the prepared silica sol. Table 1 summarizes the particle size and polishing rate measurement results of Examples 1 to 4 and Comparative Examples 1 to 3. Size 1 is the secondary particle size and the size of the final particle size, Size 2 is the primary particle size was measured after the addition of the primary catalyst.

 As a result, the relationship between the addition of the agglomerated mode silica seed sol and the particle size, when the addition of the agglomerated mode silica seed sol, affects the size of the silica particles in the final silica sol. In Table 1, <Example 1> and <Comparative Example 2> are the same type and amount of the primary catalyst and the secondary catalyst, and the presence or absence of agglomeration mode silica seed sol before the addition of the primary catalyst. In the case of <Example 1>, the final particle size is 145 nm, and in Comparative Example 2, the particle size is 71 nm. It can be seen that the cohesion is better by addition of the coagulation mode silica seed sol and the size is more than doubled. In the case of <Example 2> and <Example 3>, only the type of the agglomerated mode silica seed sol was changed, and the reaction with <Comparative Example 2> was the same. As the degree of cohesion improves nearly two times, it can be confirmed that the polishing rate is improved.

Particle photographs of Comparative Examples 1 to 3 can be seen in FIG. 6.

1 is a process flow diagram of a method for producing a chemical and mechanical polishing silica sol of the present invention.

2A and 2B are transmission electron microscope (TEM) images of a dry silica seed sol and abrasive silica particles grown with the seed sol.

3A and 3B are particle size distributions of dry silica seed sol and abrasive silica particles grown with seed sol.

4 is a transmission electron microscope (TEM) photograph of abrasive silica particles in which an acid-aggregated silica sol is grown as a seed sol in a direct oxidation process of silicon.

5 is a transmission electron microscope (TEM) photograph of abrasive silica particles in which alcohol agglomerated silica sol is grown as a seed sol in a direct oxidation process of silicon.

6A is a transmission electron microscope (TEM) photograph of monodisperse silica sol particles of Comparative Example 1 (monodispersion particles having a size of monodispersion 45 (40)).

6B is a transmission electron microscope (TEM) photograph of monodisperse silica sol particles of Comparative Example 2 (monodispersion particles having a size of monodispersion 71 (60)).

6C is a transmission electron microscope (TEM) photograph of monodisperse silica sol particles of Comparative Example 3 (monodispersion particles having a size of monodispersion 113 (100)).

Claims (11)

 Diluting the agglomerated mode silica seed sol in distilled water to form a dilution liquid,  Adding silicon powder to the diluent to prepare a first dispersion solution,  Preparing a second dispersion solution by adding a weakly basic catalyst to 0.5 parts by weight to 60 parts by weight with respect to 100 parts by weight of the silicon powder to the first dispersion solution, and reacting the same.  Preparing a third dispersion solution by adding a strong basic catalyst to 0.5 parts by weight to 10 parts by weight with respect to 100 parts by weight of the silicon powder to the second dispersion solution, Silica sol manufacturing method comprising the step of filtering the third dispersion solution. The method of claim 1, The agglomeration mode silica seed sol is any one selected from agglomeration seed sol including a seed sol, acid coagulated silica sol seed sol, agglomerated seed sol, and methyltrimethoxysilane (MTMS) in which dry silica is dispersed. Sol preparation method. The method of claim 1, The amount of the silica seed sol is a silica sol manufacturing method, characterized in that 1 to 10 parts by weight relative to 100 parts by weight of the distilled water. The method of claim 1, The amount of the silicon powder is silica sol manufacturing method, characterized in that 5 to 25 parts by weight relative to 100 parts by weight of distilled water. The method of claim 1, The second dispersion solution production step is a method for producing a silica sol, characterized in that made by reacting for 5 to 100 ℃ for 1 hour to 10 hours. The method of claim 1, The weakly basic catalyst is methyl amine, ethyl amine, n-propyl amine, n-butyl amine, dimethyl amine, diethyl Amine (dietyl amine), dipropyl amine, dibutyl amine, trimethyl amine, triethylamine, tripropyl amine, tripropyl amine, tributylamine Silamine sol process characterized in that it is selected from the group consisting of amine) and ammonium hydroxide (ammonium hydroxide).  The method of claim 1, The manufacturing step of the third dispersion solution is a silica sol manufacturing method, characterized in that made by reacting for 10 to 36 hours at 5 ℃ to 100 ℃. The method of claim 1, The strong base catalyst is silica sol (potassium hydroxide), barium hydroxide (barium hydroxide), cesium (cesium hydroxide) and lithium hydroxide (lithium hydroxide) method of producing a silica sol, characterized in that selected from the group consisting of. The method of claim 1, The particle size of the silicon powder is a method of producing a silica sol, characterized in that 50 mesh (mesh) to 1000 mesh (mesh). The method of claim 1, Method for producing a silica sol, characterized in that the silicon content of the silicon powder is 95% by weight or more. A chemical and mechanical polishing silica sol produced by any one of claims 1 to 11.

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