CN116143129B

CN116143129B - Preparation method and application of peanut-shaped ultra-high purity silica sol

Info

Publication number: CN116143129B
Application number: CN202310000484.9A
Authority: CN
Inventors: 王建宇; 卫旻嵩
Original assignee: Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd
Priority date: 2023-01-03
Filing date: 2023-01-03
Publication date: 2025-04-01
Anticipated expiration: 2043-01-03
Also published as: CN116143129A

Abstract

The invention discloses a method for preparing and applying a peanut-shaped ultra-high purity silica sol, comprising the following steps: 1) preparing an active silicic acid solution; 2) adding part of the active silicic acid solution to an alkali solution, performing an aging reaction after the dropwise addition is completed, adjusting the pH to 9-11, and obtaining a seed mother solution; 3) adding a quantitative organic ammonium salt to the seed mother solution, mixing evenly, and continuing to age at a high temperature to obtain an initial silica sol; 4) heating the initial silica sol to 80-120° C., adding the remaining active silicic acid solution to the initial silica sol under stirring, and continuing the aging reaction after the addition is completed to obtain a silica sol; 5) using ultrapure water to perform solvent replacement on the alcohol generated by the reaction, and concentrating to a silicon dioxide mass content of 20-50%; 6) filtering and removing solids in the concentrated solution to obtain a peanut-shaped ultra-high purity silica sol. The method can provide a peanut-shaped ultra-high purity silica sol, which can be widely used in CMP polishing liquid.

Description

Preparation method and application of peanut-shaped ultra-high-purity silica sol

Technical Field

The invention relates to a silica sol, in particular to a preparation method and application of peanut-shaped ultra-high purity silica sol.

Background

Silica sol is a colloidal substance obtained by dispersing silica particles in water, and is widely used in industries such as papermaking, catalysts, casting, and coating materials, and has been widely used in the semiconductor industry in recent years. In the whole manufacturing process of the semiconductor chip, tens of Chemical Mechanical Polishing (CMP) processes are required, and silica sol is a very important raw material in the CMP process. In the semiconductor manufacturing process, the presence of metal impurities, particularly metal ions, may cause short circuits between lines, and thus, in the semiconductor manufacturing process, there are various demands on the purity of the metal impurities of the chemicals used. Along with the gradual decrease of the manufacturing process of the semiconductor, the purity requirement on the silica sol is also higher and higher.

The alkoxide method is a relatively mature process for producing ultra-high purity silica sol at present, under the action of an alkali catalyst and an alcohol solvent, alkoxy silane reacts with water to generate silicon dioxide and alcohol, and the organic solvent is replaced by water to obtain the water-based silica sol. The purity of the silica sol prepared by the alkoxide method is directly related to the purity of the raw material, so that a large amount of high-purity alcohol solvent is needed, the cost of the raw material is high, and the energy consumption cost and the equipment cost are high due to the fact that separation recovery, waste liquid treatment and the like are involved in the follow-up process. In addition, the ultra-high purity silica sol prepared by the conventional alkoxide method has low hardness due to low synthesis temperature, thereby resulting in low polishing rate. In addition, in order to increase the contact area between the abrasive particles and the wafer, thereby increasing the friction force and improving the polishing rate, the shape of the abrasive is required to be peanut-shaped or irregularly shaped.

CN101641288a can control the growth rate of silica particles by adjusting the addition rate of the hydrolysate of alkyl silicate to the mother liquor, and can prepare silica particles with further reduced residual silanol groups, and correspondingly, the siloxane skeleton has high completion degree and higher grinding performance. However, the silica sol prepared by the method is spherical, and the morphology cannot be controlled.

JP2013082584A also adopts the above process to prepare ultra-high purity silica sol with higher hardness, and simultaneously controls the addition rate and pH of the active silicic acid solution and the association degree of the prepared silica, thereby preparing peanut-shaped or abnormal silica sol. However, the process needs to repeatedly prepare the active silicic acid solution and strictly control the pH value of the system, has harsh reaction conditions and complex flow, is unfavorable for industrial scale-up production, and the batch stability of the prepared silica sol is difficult to ensure.

CN112299425A uses alkali catalyst with R ₁OR₂NH₂ structure, uses water and alkoxy silane as reactants to prepare the silica sol particles with wolf tooth stick structure and surface with protruding structure and particle density of 2g/cm ³ through two-step synthesis method. Although the synthesized silica sol has a convex structure, the roughness of the particle surface can be obviously increased, and the polishing rate of CMP can be improved, the sharp surface structure can inevitably scratch a wafer or a device or generate defects during CMP, and the R ₁OR₂NH₂ catalyst adopted in the synthesis method belongs to organic ammonium with the boiling point of more than 100 ℃ and is difficult to remove in the subsequent treatment process, so that the silica sol is difficult to use in certain polishing solutions (such as metal polishing solutions) which are relatively sensitive to organic ammonium, and does not have universality.

Disclosure of Invention

In order to solve the technical problems, the invention provides a preparation method and application of peanut-shaped ultra-high purity silica sol. The method can provide peanut-shaped ultra-high purity silica sol and can be widely applied to CMP polishing liquid.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

the preparation method of the peanut-shaped ultra-high purity silica sol comprises the following steps:

1) Adding alkoxy silane into a mixed solution of organic acid and ultrapure water to prepare an active silicic acid solution;

2) Slowly dripping active silicic acid solution into alkali liquor, reacting while stirring, adding alkali liquor to maintain the pH of the system at 9-11, aging after adding, and maintaining the pH of the system at 9-11 during aging to obtain seed mother liquor;

3) Adding quantitative organic ammonium salt into the seed mother solution, uniformly mixing, and continuing aging reaction at high temperature to prepare initial silica sol;

4) Heating the initial silica sol to 80-120 ℃, preferably 90-110 ℃, slowly adding an active silicic acid solution under the stirring condition, and continuing the aging reaction after the addition is finished to obtain the silica sol;

5) Performing solvent replacement on alcohol generated by the reaction by adopting ultrapure water, and concentrating until the mass content of silicon dioxide is 20-50%;

6) Filtering to remove solid in the concentrated solution, and obtaining peanut-shaped ultra-high purity silica sol.

As a preferred embodiment, in step 1), the organic acid is used in an amount of 100 to 1500ppm, relative to the molar amount of alkoxysilane;

preferably, the amount of ultrapure water used in step 1) is 40 to 150 times the molar amount of alkoxysilane;

preferably, the organic acid is one or more of formic acid, acetic acid, propionic acid, benzoic acid, salicylic acid, oxalic acid, malonic acid, maleic acid, fumaric acid, glycolic acid, glyceric acid, lactic acid, tartaric acid, malic acid, and citric acid;

Preferably, the alkoxysilane is one or more of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, preferably tetramethoxysilane or tetraethoxysilane.

As a preferred embodiment, in step 1), the reaction temperature is between 10 and 40 ℃, the stirring time is between 0.5 and 3 hours, and the stirring speed is between 200 and 1000r/min;

preferably, the reaction temperature is between 10 and 15 ℃, the stirring time is between 0.5 and 1h, and the stirring speed is between 200 and 500r/min.

In a preferred embodiment, in the step 2), the alkali in the alkali liquor is selected from alkali metal hydroxide, organic amine and guanidine compound, preferably, the alkali metal hydroxide is at least one of potassium hydroxide, sodium hydroxide and lithium hydroxide, the organic amine is at least one of ammonia, ethylenediamine, triethanolamine and tetramethyl ammonium hydroxide, the guanidine compound is at least one of tetramethyl guanidine, trimethyl guanidine and guanidine carbonate, and the alkali liquor is preferably ammonia water.

Preferably, the alkali concentration in the alkali liquor in step 2) is 1-2% by mass.

As a preferred embodiment, the reaction conditions of the active silicic acid solution and the alkali liquor in the step 2) are that the reaction temperature is 80-120 ℃, the stirring rotation speed is 200-1000r/min, the reaction temperature is 90-110 ℃ and the stirring rotation speed is 200-500r/min;

preferably, the active silicic acid solution in step 2) is added dropwise to the alkaline solution for 3-6 hours;

Preferably, the ageing time in step 2) is 2 to 8 hours, preferably 3 to 6 hours.

In step 3), the organic ammonium salt is added in an amount of 0.1 to 5%, preferably 0.5 to 2% of the silica content of the seed mother liquor;

Preferably, the organic ammonium salt is one or more of ammonium formate, ammonium acetate, ammonium propionate, ammonium benzoate, ammonium salicylate, ammonium oxalate, ammonium malonate, ammonium maleate, ammonium fumarate, ammonium glycolate, ammonium glycerate, ammonium lactate, ammonium tartrate, ammonium malate, and ammonium citrate, and the inorganic ammonium salt is one or more of ammonium phosphate, ammonium dihydrogen phosphate, ammonium bicarbonate, ammonium sulfate, ammonium chloride, and ammonium nitrate.

As a preferred embodiment, the high temperature aging conditions in step 3) are an aging temperature of 60 to 120 ℃, an aging time of 2 to 8 hours, a stirring speed of 0 to 300r/min, preferably an aging temperature of 80 to 110 ℃, an aging time of 3 to 6 hours, and a stirring speed of 0 to 100r/min.

As a preferred embodiment, the amount of active silicic acid solution used in step 4) is 10-50 times the initial silica sol mass;

Preferably, the time for which the reactive silicic acid solution is added dropwise to the initial silica sol in step 4) is 3 to 6 hours;

Preferably, the stirring speed in step 4) is 200-1000r/min, preferably 200-500r/min;

Preferably, the ageing reaction time in step 4) is 2 to 8 hours, preferably 3 to 6 hours.

Preferably, the solvent displacement in step 5) is by heat or ultrafiltration, more preferably by vacuum heat or ultrafiltration membrane, to reduce the alcohol content to below 200ppm, preferably below 100 ppm.

Preferably, in the step 6), the filter element made of PFA material is adopted, preferably two-stage or three-stage filtration is adopted, and the filtration precision is 0.2-5 mu m.

According to the invention, by a two-step growth method and adding quantitative organic ammonium salt into the seed mother liquor, peanut-shaped ultra-high purity silica sol with particle size of 20-100nm, peanut shape, association degree of 1.7-2.2 and density of more than 2g/cm ³ can be prepared, the polishing rate can be remarkably improved, and scratches on a substrate during polishing can be reduced due to the smooth peanut morphology of colloidal particles.

The application of peanut-shaped ultra-high purity silica sol prepared by the method in CMP polishing liquid.

The beneficial effects of the invention are as follows:

(1) The invention adds organic ammonium salt into the prepared seed mother solution, and then prepares the high-purity silica sol with high hardness and peanut-shaped colloidal particles through secondary growth.

(2) The silica sol prepared by the invention has higher polishing rate, and the surface of the colloidal particle has a smooth structure, so that scratches and defects formed in the polishing process can be effectively reduced while the polishing rate is ensured, and the silica sol can be widely applied to polishing liquid.

(3) The silica sol prepared by the method does not contain an organic base catalyst which is difficult to separate, has stronger universality and can be better applied to the field of high-end CMP polishing.

(4) The production process provided by the invention has the advantages of simple process and higher batch stability, and is more beneficial to industrial production.

Drawings

Fig. 1 is a TEM morphology of silica sol gel particles prepared in example 1.

Fig. 2 is a TEM morphology of silica sol colloidal particles prepared in comparative example 1.

Detailed Description

The invention will now be further illustrated by means of specific examples which are given solely by way of illustration of the invention and do not limit the scope thereof.

The starting materials and reagents used in the following examples and comparative examples were all commercially available.

The main test methods used in the following examples and comparative examples are as follows:

the solid content test method refers to HGT 2521-2008 industrial silica sol.

The secondary particle size of the silica sol colloidal particle is measured by a Markov particle analyzer Zetasizer Nano ZS, the primary particle size is firstly measured by a BET specific surface area measurement method to obtain a specific surface area S _bet, and then the primary particle size is calculated by a formula 2727/S _bet. The degree of association is the ratio of the secondary particle size to the primary particle size.

The apparent morphology of the silica sol was characterized by TEM.

The concentration of metal ions was tested using Agilent 8900 ICP-MS.

The real density of the colloidal particles is tested by a real density meter.

Example 1

(1) 0.019G of citric acid is added to 1800g of water to prepare an aqueous solution of citric acid, then 152g of tetramethoxysilane is added to the aqueous solution of citric acid, and the mixture is stirred and reacted for 1 hour at 15 ℃ at a stirring speed of 200r/min to obtain an aqueous solution of active silicic acid with a mass concentration (calculated as SiO ₂) of 3.07%.

(2) 10G of ammonia (25 wt%) were dissolved in 185.2g of deionized water to give a lye with pH=11. Slowly dripping 1952g of active silicic acid solution into the alkali liquor at 100 ℃ for 3 hours, monitoring the pH of the system in the dripping process and adding the alkali liquor to maintain the pH at 9-10, continuing the aging reaction for 3 hours after the alkali liquor is completely dripped, adding the alkali liquor to maintain the pH at 9-10 in the aging process, and finally obtaining the spherical silica seed mother liquor with the primary particle size of 15nm, wherein the mass concentration of SiO ₂ is 2.79wt%.

(3) Ammonium citrate which is 0.5 percent relative to the mass of silicon dioxide in the seed mother solution is added into the seed mother solution, and after the reaction is carried out for 3 hours at 90 ℃, the stirring speed is 100r/min, and the initial silica sol with the secondary particle size of 35nm and the primary particle size of 15nm is obtained.

(4) Taking 100g of initial silica sol, heating to 100 ℃, slowly dripping 2882g of active silicic acid solution into the initial silica sol, dripping for 3 hours, wherein the stirring speed in the dripping process is 200r/min, and continuing the aging reaction for 3 hours after the dripping is finished.

(5) Adopting a constant liquid level heating concentration mode, adding water while evaporating until the alcohol content in the silica sol is reduced to below 100ppm, and concentrating until the silicon dioxide content is 20%.

(6) And (3) after concentration, filtering twice by adopting filter cores with the filtering grades of 1 mu m and 0.5 mu m respectively, and removing solids to obtain the peanut-shaped ultra-high purity silica sol.

[ Example 2]

(1) 0.201G of malic acid is added into 792g of water to prepare an aqueous solution of malic acid, then 208g of tetramethoxysilane is added into the aqueous solution of malic acid, and the mixture is stirred and reacted for 1h at 15 ℃ at a stirring speed of 300r/min to obtain an aqueous solution of active silicic acid with a mass concentration (calculated as SiO ₂) of 6%.

(2) 10G of tetramethylammonium hydroxide was dissolved in 190g of deionized water to give a lye with ph=10. Slowly dripping 1000g of active silicic acid solution into the alkali liquor at 90 ℃ for 6 hours, monitoring the pH of the system in the dripping process and supplementing the alkali liquor to maintain the pH at 9-10, continuing the aging reaction for 3 hours after the dripping is finished, supplementing the alkali liquor to maintain the pH at 9-10 in the aging process, and finally obtaining the spherical silica seed mother liquor with the primary particle size of 20nm, wherein the mass concentration of SiO ₂ is 5wt%.

(3) Adding ammonium malate accounting for 2% of the mass of silicon dioxide in the seed mother solution into the seed mother solution, reacting for 3 hours at 90 ℃, and stirring at a speed of 100r/min to obtain initial silica sol with a secondary particle size of 45nm and a primary particle size of 20 nm.

(4) And heating 100g of the initial silica sol to 90 ℃, slowly dripping 1000g of active silicic acid solution into the initial silica sol for 6 hours, wherein the stirring speed is 400r/min in the dripping process, and continuing the aging reaction for 6 hours after the dripping is finished.

[ Example 3]

(1) 0.019G of malonic acid is added into 1236g of water to prepare an aqueous malonic acid solution, 264g of tetrapropoxysilane is added into the aqueous malonic acid solution, and the mixture is stirred and reacted for 1h at 10 ℃ at a stirring speed of 200r/min to obtain an aqueous active silicic acid solution with a mass concentration (calculated as SiO ₂) of 4.5%.

(2) 0.01G of potassium hydroxide was dissolved in 200g of deionized water to give an alkaline solution with ph=11. Slowly dripping 1500g of active silicic acid solution into the alkali liquor at 110 ℃ for 4.5 hours, monitoring the pH of the system in the dripping process and adding the alkali liquor to maintain the pH at 10-11, continuing the aging reaction for 4.5 hours after the dripping is finished, adding the alkali liquor to maintain the pH at 10-11 in the aging process, and finally obtaining spherical silica seed mother liquor with the primary particle size of 10nm, wherein the mass concentration of SiO ₂ is 3.97wt%.

(3) Adding ammonium phosphate which is 1.5 percent of the mass of silicon dioxide in the seed mother solution into the seed mother solution, reacting for 4.5 hours at 110 ℃, and obtaining the initial silica sol with the secondary particle size of 20nm and the primary particle size of 10nm, wherein the stirring speed is 100 r/min.

(4) 130G of the initial silica sol is heated to 110 ℃, 2477g of active silicic acid solution is slowly dripped into the initial silica sol, the total dripping is carried out for 4.5 hours, the stirring speed is 300r/min in the dripping process, and the aging reaction is continued for 4.5 hours after the dripping is finished.

[ Example 4]

(1) 0.019G of malic acid is added into 1800g of water to prepare an aqueous solution of malic acid, then 152g of tetramethoxysilane is added into the aqueous solution of malic acid, and the mixture is stirred and reacted for 1h at 15 ℃ at a stirring speed of 200r/min to obtain an aqueous solution of active silicic acid with a mass concentration (calculated by SiO ₂) of 3.07 percent.

(2) 15G of tetramethylguanidine are dissolved in 185.2g of deionized water to give an alkaline solution with pH=10. Slowly dripping 1952g of active silicic acid solution into the alkali liquor at 100 ℃ for 3 hours, monitoring the pH of the system in the dripping process and adding the alkali liquor to maintain the pH at 9-10, continuing the aging reaction for 3 hours after the dripping is finished, adding the alkali liquor to maintain the pH at 9-10 in the aging process, and finally obtaining spherical silica seed mother liquor with the primary particle size of 20nm, wherein the mass concentration of SiO ₂ is 2.78wt%.

(3) Adding ammonium citrate which is 1% of the mass of silicon dioxide in the seed mother solution into the seed mother solution, reacting for 3 hours at 90 ℃, and stirring at a speed of 100r/min to obtain initial silica sol with a secondary particle size of 42nm and a primary particle size of 20 nm.

(4) 60G of the initial silica sol is heated to 100 ℃, 3615g of active silicic acid solution is slowly dripped into the initial silica sol, the total dripping is carried out for 3 hours, the stirring speed in the dripping process is 200r/min, and after the dripping is finished, the aging reaction is continued for 3 hours.

[ Example 5]

(1) 0.019G of citric acid was added to 848g of water to prepare an aqueous citric acid solution, and then 152g of tetramethoxysilane was added to the aqueous citric acid solution, and the mixture was stirred at 15℃for reaction for 1 hour at a stirring speed of 200r/min to obtain an aqueous active silicon acid solution having a mass concentration (based on SiO ₂) of 6%.

(2) 10G of ammonia (25 wt%) were dissolved in 185.2g of deionized water to give a lye with pH=10. Slowly dripping 1000g of active silicic acid solution into the alkali liquor at 100 ℃ for 6 hours, monitoring the pH of the system in the dripping process and supplementing the alkali liquor to maintain the pH at 9-10, continuing the aging reaction for 3 hours after the dripping is finished, supplementing the alkali liquor to maintain the pH at 9-10 in the aging process, and finally obtaining the spherical silica seed mother liquor with the primary particle size of 25nm, wherein the mass concentration of SiO ₂ is 5.02wt%.

(3) Adding ammonium citrate which is 1.5 percent of the mass of silicon dioxide in the seed mother solution into the seed mother solution, reacting for 3 hours at 100 ℃, and obtaining the initial silica sol with the secondary particle size of 50nm and the primary particle size of 25nm, wherein the stirring speed is 100 r/min.

(4) And heating 90g of the initial silica sol to 100 ℃, slowly dripping 900g of active silicic acid solution into the initial silica sol for 6 hours, wherein the stirring speed is 300r/min in the dripping process, and continuing the aging reaction for 3 hours after the dripping is finished.

Comparative example 1

Silica sol was prepared in substantially the same manner as in example 1, except that ammonium citrate was not added in step (3).

The silica sols prepared in each example and comparative example were subjected to the parameter test in table 1, and the test results are as follows. TEM images of silica sol colloidal particles prepared in example 1 and comparative example 1 are shown in FIGS. 1 and 2, respectively.

TABLE 1 silica sol test results

The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and additions may be made to those skilled in the art without departing from the method of the present invention, which modifications and additions are also to be considered as within the scope of the present invention.

Claims

1. A method for preparing peanut-shaped ultra-high purity silica sol, characterized in that it comprises the following steps:

1) adding alkoxysilane to a mixed solution of an organic acid and ultrapure water to prepare an active silicic acid solution;

2) Slowly drop the active silicate solution into the alkali solution, react while stirring and add alkali solution to maintain the pH of the system at 9-11. After the addition is completed, age the solution and maintain the pH of the system at 9-11 during the aging process to obtain a seed mother solution;

3) Adding a certain amount of organic ammonium salt to the seed mother solution, mixing evenly and continuing the aging reaction at high temperature to prepare the initial silica sol; the amount of organic ammonium salt added is 0.1-5% of the silica content in the seed mother solution;

4) The initial silica sol is heated to 80-120°C, and the active silicic acid solution is slowly added under stirring. After the addition is completed, the aging reaction is continued to obtain the silica sol; the amount of the active silicic acid solution used is 10-50 times the mass of the initial silica sol;

5) Using ultrapure water to replace the alcohol produced by the reaction, and concentrating it to a silica mass content of 20-50%;

6) Filter and remove the solids in the concentrated solution to obtain peanut-shaped ultra-high purity silica sol.

2. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 1, characterized in that in step 4), the initial silica sol is heated to 90-110°C and then the active silicic acid solution is added.

3. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 1, characterized in that in step 1), the amount of the organic acid used is 100-1500 ppm, relative to the molar amount of alkoxysilane.

4. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 3, characterized in that the amount of ultrapure water used in step 1) is 40-150 times the molar amount of alkoxysilane.

5. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 3, characterized in that the organic acid is one or more of formic acid, acetic acid, propionic acid, benzoic acid, salicylic acid, oxalic acid, malonic acid, maleic acid, fumaric acid, glycolic acid, glyceric acid, lactic acid, tartaric acid, malic acid, and citric acid.

6. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 3, characterized in that the alkoxysilane is one or more of tetramethoxysilane, tetraethoxysilane and tetrapropoxysilane.

7. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 3, characterized in that in step 1), the reaction temperature is between 10-40°C, the stirring time is 0.5h-3h, and the stirring speed is 200-1000r/min.

8. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 7, characterized in that in step 1), the reaction temperature is between 10-15°C, the stirring time is 0.5-1h, and the stirring speed is 200-500r/min.

9. The method for preparing peanut-shaped ultra-high purity silica sol according to any one of claims 1 to 8, characterized in that in step 2), the alkali solution is at least one of alkali metal hydroxide, organic amine, and guanidine compound solution.

10. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 9, characterized in that the alkali metal hydroxide is selected from at least one of potassium hydroxide, sodium hydroxide, and lithium hydroxide, the organic amine is selected from at least one of ammonia, ethylenediamine, triethanolamine, and tetramethylammonium hydroxide, and the guanidine compound is selected from at least one of tetramethylguanidine, trimethylguanidine, and guanidine carbonate.

11. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 9, characterized in that the reaction conditions for adding the active silicic acid solution dropwise to the alkali solution in step 2) are: reaction temperature 80-120°C, stirring speed 200-1000 r/min.

12. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 11, characterized in that the reaction conditions for adding the active silicic acid solution dropwise to the alkali solution in step 2) are: reaction temperature 90-110°C, stirring speed 200-500 r/min.

13. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 11, characterized in that the time for dripping the active silicic acid solution into the alkaline solution in step 2) is 3-6 hours.

14. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 11, characterized in that the aging time in step 2) is 2-8 hours.

15. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 14, characterized in that the aging time in step 2) is 3-6 hours.

16. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 1, characterized in that in step 3), the amount of organic ammonium salt added is 0.5-2% of the silicon dioxide content in the seed mother solution.

17. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 1, characterized in that the organic ammonium salt is selected from ammonium formate, ammonium acetate, ammonium propionate, ammonium benzoate, ammonium salicylate, ammonium oxalate, ammonium malonate, ammonium maleate, ammonium fumarate, ammonium hydroxyacetate, ammonium glycerate, ammonium lactate, ammonium tartrate, ammonium malate, and ammonium citrate.

18. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 1, characterized in that the high temperature aging conditions in step 3) are: aging temperature is 60-120°C, aging time is 2-8h, and stirring speed is 0-300r/min.

19. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 18, characterized in that the high temperature aging conditions in step 3) are: aging temperature is 80-110°C, aging time is 3-6h, and stirring speed is 0-100r/min.

20. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 1, characterized in that the time for dripping the active silicic acid solution into the initial silica sol in step 4) is 3-6 hours.

21. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 20, characterized in that the stirring speed in step 4) is 200-1000 r/min.

22. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 21, characterized in that the stirring speed in step 4) is 200-500 r/min.

23. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 20, characterized in that the aging reaction time in step 4) is 2-8 hours.

24. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 23, characterized in that the aging reaction time in step 4) is 3-6 hours.

25. The method for preparing peanut-shaped ultra-high purity silica sol according to any one of claims 1 to 8, characterized in that the solvent replacement in step 5) is carried out by heating concentration or ultrafiltration concentration to reduce the alcohol content to below 200 ppm.

26. The method for preparing peanut-shaped ultra-high purity silica sol according to claim 25, characterized in that the solvent replacement in step 5) is carried out by heating concentration or ultrafiltration concentration to reduce the alcohol content to below 100 ppm.

27. Use of peanut-shaped ultra-high purity silica sol prepared by the method according to any one of claims 1 to 26 in CMP polishing liquid.