CN117842999A - Ultra-high purity silica sol with surface provided with raised structures, preparation method and application thereof - Google Patents

Ultra-high purity silica sol with surface provided with raised structures, preparation method and application thereof Download PDF

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CN117842999A
CN117842999A CN202410001203.6A CN202410001203A CN117842999A CN 117842999 A CN117842999 A CN 117842999A CN 202410001203 A CN202410001203 A CN 202410001203A CN 117842999 A CN117842999 A CN 117842999A
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silica sol
acid
solution
water
alcohol
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王建宇
马吉全
纪学顺
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Wanhua Chemical Group Co Ltd
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Wanhua Chemical Group Co Ltd
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Abstract

The invention discloses ultra-high purity silica sol with a convex structure on the surface, a preparation method and application thereof, wherein the preparation method comprises the following steps: (1) Preparing initial seed crystal with particle size of 5-10nm by adding mixture of alkoxy silane and alcohol into mixture of alcohol, alkali and water at a certain speed; (2) Alkali liquor with pH value of 8-11 is used as priming solution, a certain amount of inorganic acid, organic acid or one or more of inorganic acid ammonium and organic acid ammonium is added into the priming solution, the prepared seed crystal solution is used as a silicon source, and the seed crystal solution is fed at a certain feeding speed for secondary growth, so that the silica sol with the surface having a convex structure can be prepared. The invention provides a simple method for preparing silica sol by regulating and controlling the protruding morphology of the particle surface.

Description

Ultra-high purity silica sol with surface provided with raised structures, preparation method and application thereof
Technical Field
The invention belongs to the field of nano material preparation, and particularly relates to ultra-high purity silica sol with a raised structure on the surface, a preparation method and application thereof in the field of semiconductor CMP (chemical mechanical polishing).
Background
Silica sol is a colloidal substance obtained by dispersing silica particles in water or other solvents, and is widely used in the industries of papermaking, catalysts, casting, paints, and the like. In recent years, silica sol is widely used in the semiconductor industry, and several tens of CMP are required in the entire manufacturing process of semiconductor chips, and silica sol is a very important raw material in CMP polishing solutions. With the development of semiconductor and information industries, the consumption and performance requirements of CMP consumables are higher and higher. Silica sol, one of the core materials for CMP slurry, also places higher demands on its polishing performance and purity.
Chemical mechanical polishing, CMP for short, forms a layer of softening layer under the action of corrosive medium of polishing solution under the existence of certain pressure and polishing slurry by means of the combined action of chemistry and machinery, and abrasive particles in the polishing solution grind the softening layer, so that nano global planarization is realized. Therefore, the physical properties of the abrasive, such as particle size, morphology, hardness, etc., have a large influence on the polishing rate. At present, most of the commercially available silica sol particles are spherical, the surfaces of the particles are smooth, rolling friction is generated in the polishing process, and the polishing rate is not as high as that of sliding friction particles.
The patent JPA 2005060217 is characterized in that the mixture of tetramethoxysilane and methanol is dropwise added into the mixture of methanol, ammonia water and water to prepare the peanut-shaped ultra-pure silica sol with association degree of 2, and compared with spherical particles prepared by the same method, the polishing rate is improved. Patent CN103896287a provides a method for preparing a non-spherical silica sol, but the use of divalent metal and styrene in the preparation process introduces the risk of metal ions remaining on the surface of the work piece, the remaining of metal ions being fatal to the manufacture of semiconductor chips, and the styrene coated on the particle surface being hydrophobic, which affects the storage stability of the silica sol. Patent JP 2006303507A uses quaternary ammonium salt as a catalyst to prepare silica sol with a convex structure on the surface, so that the polishing rate is effectively improved.
Disclosure of Invention
In order to improve the polishing rate of the silica sol, the invention creatively provides a preparation method of the ultra-high purity silica sol with a convex structure on the surface. The method comprises the steps of firstly preparing seed crystals of 5-10nm by dripping a mixture of alkoxy silane and alcohol into a mixture of alcohol, water and a base catalyst, and then dripping the seed crystal solution into an alkali solution, so as to prepare silica sol particles with a convex structure on the surface.
It is another object of the present invention to provide such ultra-high purity silica sol having a raised structure on the surface.
It is a further object of the present invention to provide the use of such ultra-high purity silica sols having raised structures on their surface.
In order to achieve the aim of the invention, the invention adopts the following technical scheme:
the preparation method of the ultra-high purity silica sol with the raised structure on the surface comprises the following steps:
1) Preparation of seed crystal: mixing alcohol and deionized water, and adjusting pH with alkali to obtain base solution A 1 Then, under stirring, a mixture of alkoxysilane and alcohol was used as the silicon source B 1 With silicon source B 1 To the priming solution A for feeding 1 Obtaining seed crystal solution B 2 ；
2) And (3) secondary growth: mixing alcohol, alkali and water as base solution A 2 Adjustment A 2 At pH of priming solution A 2 Adding acidic compound into the solution A 2 Heating and stirring the seed crystal solution B in the step 1) 2 To the priming solution A for feeding 2 Maintaining the liquid level constant during the process, and continuing aging after the material is fed to obtain initial silica sol;
3) Solvent displacement and concentration: displacing alcohol in the initial silica sol with ultrapure water, and concentrating to 20% or more;
4) And (3) filtering: and filtering the concentrated silica sol to remove large particles to obtain the ultra-high purity silica sol with the surface provided with the convex structure, wherein the mass fraction of the ultra-high purity silica sol is more than 20%.
In some specific embodiments, the alkoxysilane described in step 1) is one or more of tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, preferably tetramethoxysilane;
in some specific embodiments, the alcohol is a small molecule alcohol of C1-C6, preferably one or more of methanol, ethanol, ethylene glycol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, 1-hexanol, more preferably methanol or ethanol;
in some embodiments, the deionized water has a resistivity above 15mΩ.cm, for example 15mΩ.cm, 16mΩ.cm, 17mΩ.cm, 18mΩ.cm, etc., preferably greater than 18mΩ.cm;
in some specific embodiments, the base in step 1) is selected from at least any one of alkali metal hydroxide, ammonia, organic amine or guanidine compound; preferably, the alkali metal hydroxide is selected from at least any one of potassium hydroxide, sodium hydroxide and lithium hydroxide, the organic amine is selected from at least any one of ethylenediamine, triethanolamine and tetramethyl ammonium hydroxide, and the guanidine compound is selected from at least any one of tetramethyl guanidine, trimethyl guanidine and guanidine carbonate; more preferably, the base catalyst is selected from any one of ammonia, ethylenediamine or tetramethylammonium hydroxide.
In some preferred embodiments, the priming solution A in step 1) is 1 The mass ratio of the medium alcohol to the water is 0-10:1, for example 0: 1. 1: 1. 2: 1. 3: 1. 3.5: 1. 4: 1. 5:1. 6: 1. 7: 1. 7.5: 1. 8: 1. 9: 1. 10:1, etc.; base-adjusting primer A 1 The pH of (C) is 7.5-11, for example 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, etc., preferably 9-11.
In some preferred embodiments, the silicon source B 1 The mass ratio of the medium alcohol to the alkoxysilane is between 1:3 and 10:1, for example 1: 3. 1: 2. 1: 1. 2: 1. 2.5: 1. 3: 1. 4: 1. 5:1. 6: 1. 7: 1. 8: 1. 9: 1. 10:1, etc.
In some preferred embodiments, the silicon source B 1 With priming solution A 1 The volume ratio of (1:20) to (5:1), for example 1: 20. 1: 15. 1: 10. 1:5. 1: 1. 2: 1. 3: 1. 4: 1. 5:1, etc.
In some specific embodiments, the stirring conditions in step 1) are at a temperature of 10-100deg.C, such as 10deg.C, 20deg.C, 30deg.C, 40deg.C, 50deg.C, 60deg.C, 70deg.C, 80deg.C, 90deg.C, 100deg.C, preferably 10deg.C-60deg.C;
in some specific embodiments, the stirring time in step 1) is from 0.5h to 3h, such as 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, etc., preferably from 0.5 to 1h, performing H; the stirring speed is 100-1000r/min, such as 100r/min, 200r/min, 300r/min, 400r/min, 500r/min, 600r/min, 700r/min, 800r/min, 900r/min, 1000r/min, etc., preferably 200-500r/min; the silicon source B 1 The feed time of (2) is 10min to 10h, for example 10min, 30min, 1h, 1.5h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, preferably 10min to 5h.
In some specific embodiments, the base in step 2) is at least one selected from alkali metal hydroxide, ammonia, organic amine or guanidine compound; preferably, the alkali metal hydroxide is selected from at least any one of potassium hydroxide, sodium hydroxide and lithium hydroxide, the organic amine is selected from at least any one of ethylenediamine, triethanolamine and tetramethyl ammonium hydroxide, and the guanidine compound is selected from at least any one of tetramethyl guanidine, trimethyl guanidine and guanidine carbonate; more preferably, the base catalyst is selected from ammonia, ethylenediamine or tetramethylammonium hydroxide; the base catalyst used in step (2) is generally the same as the same base catalyst used in step (1).
In some specific embodiments, the priming solution A of step 2) is 2 The pH of (2) is between 8 and 11, for example, the pH is 8,9, 10, 11, preferably between 8 and 10;
in some specific embodiments, the priming solution A of step 2) is 2 With seed solution B 2 The volume ratio of (1): 10-1:1, for example 1: 10. 1: 9. 1: 8. 1: 7. 1: 6. 1:5. 1: 4. 1: 3. 1: 2. 1:1, preferably at 1:10-1:5.
In some specific embodiments, the acidic compound in step 2) is selected from one or more of an inorganic acid, an organic acid, or an ammonium salt thereof; wherein the organic acid is one or more of formic acid, acetic acid, oxalic acid, malic acid, citric acid, tartaric acid, lactic acid, gluconic acid, ethylenediamine tetraacetic acid, fumaric acid, methanesulfonic acid and the like; the inorganic acid is one or more of hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid and boric acid; the ammonium salt is selected from one or more of the inorganic acid or the corresponding inorganic acid ammonium or organic acid ammonium of the organic acid.
In some specific embodiments, the acidic compound in step 2) is added in an amount of between 500ppm and 5wt%, e.g. 500ppm, 1000ppm, 2000ppm, 5000ppm, 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, etc., preferably 500ppm to 2wt%, of the added alkoxysilane, calculated as silica mass.
In some specific embodiments, the stirring conditions in step 2) are at a temperature of 20-100 ℃, e.g., 20 ℃, 30 ℃, 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃, 90 ℃, 100 ℃, preferably 50-90 ℃; the stirring speed is 200-1000r/min, such as 200r/min, 300r/min, 400r/min, 500r/min, 600r/min, 700r/min, 800r/min, 900r/min, 1000r/min, etc., preferably 200-500r/min; seed solution B 2 The feed rate of (2) is 1-10ml/min, for example 1ml/min, 2ml/min, 3ml/min, 4ml/min, 5ml/min, 6ml/min, 7ml/min, 8ml/min, 9ml/min, 10ml/min, preferably 1.5-8ml/min.
In some specific embodiments, the solvent replacement in step 3) is performed by adding ultrapure water while heating, evaporating the solvent from the water, or by ultrafiltration, adding ultrapure water while concentrating until the solvent content in the silica sol is reduced to less than 200ppm, preferably less than 100 ppm.
In some specific embodiments, the concentration in the step 3) is vacuum heating concentration or ultrafiltration membrane concentration, and the mass fraction of the silica sol is concentrated to more than 20%.
In some specific embodiments, the filtering in the step 4) is performed by using a filter element made of PFA or PP, and two-stage or three-stage filtering is performed, where the filtering precision is 0.2 μm to 5 μm.
In a specific embodiment, the method for preparing the non-spherical silica sol of the present invention, for example, comprises the steps of:
1) Preparation of seed crystal: mixing alcohol and water in a certain proportion, and then regulating pH value by alkali to obtain base solution A 1 Then, at a certain temperature and stirring speed, a mixture of alkoxysilane and alcohol in a certain proportion is used as a silicon source B 1 Will B 1 Adding the mixture into the priming solution A at a certain feeding speed 1 Obtaining seed crystal solution B 2 ；
2) And (3) secondary growth: mixing alcohol, alkali and water in a certain proportion to obtain a base solution A 2 Adjustment A 2 Adding a certain amount of one or more of inorganic acid, organic acid, inorganic acid ammonium or organic acid ammonium into the priming solution within a certain pH range, and adding A 2 Heating to a certain temperature, stirring at a certain stirring speed to obtain a mixture B 2 At a certain feeding rate into A 2 Maintaining the liquid level constant during the process, and after the material is fed, continuing aging for a certain time to obtain initial silica sol;
3) Solvent displacement and concentration: displacing alcohol in the initial silica sol with ultrapure water, and concentrating to 20% or more;
4) And (3) filtering: and filtering the concentrated silica sol to remove large particles to obtain the ultra-high purity silica sol with the surface provided with the convex structure, wherein the mass fraction of the ultra-high purity silica sol is 20% or more.
On the other hand, the surface of the ultra-high purity silica sol prepared by the invention has a convex structure, and the total gold impurity content is less than 1ppm.
In still another aspect, the silica sol with a raised structure on the surface or the silica sol with a raised structure on the surface prepared by the preparation method of the invention is applied to the field of semiconductor CMP polishing.
Compared with the prior art, the invention has the following beneficial effects:
1) The invention relates to a preparation method of ultra-high purity silica sol with a raised structure on the surface, which comprises the steps of firstly preparing seed crystals with the size of 5-10nm by dripping a mixture of alkoxy silane and alcohol into a mixture of alcohol, water and an alkali catalyst, then dripping a seed crystal solution into alkaline water, and preparing silica sol particles with the raised structure on the surface by utilizing inter-particle self-assembly.
2) The silica sol particles with the convex structures can effectively improve the polishing rate.
Drawings
Fig. 1 is a TEM image of silica sol particles prepared in example 1 and comparative example 1 of the present invention.
Fig. 2 is an SEM image of silica sol particles prepared in example 1 and comparative example 1 of the present invention.
Fig. 3 is a TEM image of silica sol particles prepared in comparative examples 2 and 3 according to the present invention.
Detailed Description
In order to better understand the technical solution of the present invention, the following further illustrates the preparation method of the present invention by way of more specific examples, without any limitation.
The main raw materials used in the following examples and comparative examples are as follows:
the detection method comprises the following steps:
the solid content test method refers to HGT 2521-2008 industrial silica sol.
The secondary particle size of the silica sol colloidal particles is measured by a Markov particle sizer Zetasizer Nano ZS, and the primary particle size is measured by a BET specific surface area measurement method to obtain a specific surface area S bet Primary particle size of 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 and SEM.
The concentration of metal ions was tested using Agilent 8900 ICP-MS.
Example 1
Taking 1500g of methanol and 500g of water, adjusting the pH to 10 by ammonia water, and fully stirring and uniformly mixing to obtain A 1 Mixing 150g of methyl orthosilicate and 50g of methanol uniformly to obtain solution B 1 Liquid, at 50 ℃, B is added 1 The liquid was added to A at a feed rate of 5ml/min 1 In the liquid, the stirring speed is 500r/min. After the feeding is finished, the mixture is aged for 1 hour to obtain seed crystal solution B with the primary particle diameter of 5nm 2 . 600g of water was taken and the pH was adjusted to 10 with ammonia water as a primer solution A 2 Adding 0.6g of citric acid, mixing well, and adding B at 80deg.C 2 Drop-wise adding to A at a rate of 2ml/min 2 The stirring speed was 500r/min, and the liquid level was maintained constant during this period. And after the feeding is finished, continuing to age for 3 hours to obtain the initial silica sol.Adopting a constant liquid level heating concentration mode, adding water while evaporating until the methanol content of the silica sol is reduced to below 1000ppm, concentrating to 20%, and filtering by adopting a filter element with a filtering grade of 1 mu m and 0.5 mu m after concentrating to obtain the ultra-high purity silica sol with the total metal ion content of less than 1ppm and a convex structure on the surface.
Example 2
1000g of methanol and 1000g of water are taken, the pH value is adjusted to 9.5 by ammonia water, and the mixture is fully stirred and uniformly mixed to be used as A 1 Mixing 150g of methyl orthosilicate and 450g of methanol uniformly to obtain solution B 1 Liquid, at 30 ℃, B is added 1 The liquid was added to A at a feed rate of 15ml/min 1 In the liquid, the stirring speed is 300r/min. After the feeding is finished, the mixture is aged for 1 hour to obtain seed crystal solution B with the primary particle diameter of 10nm 2 . 400g of water and 200g of methanol are taken, the pH is adjusted to 9.5 by ammonia water, and the solution is taken as base solution A 2 Adding 0.06g of acetic acid, mixing uniformly, and then adding B at 70 DEG C 2 Drop-wise adding to A at a rate of 4ml/min 2 The stirring speed was 300r/min, and the liquid level was maintained constant during this period. And after the feeding is finished, continuing to age for 3 hours to obtain the initial silica sol. Adopting a constant liquid level heating concentration mode, adding water while evaporating until the methanol content of the silica sol is reduced to below 1000ppm, concentrating to 20%, and filtering by adopting a filter element with a filtering grade of 1 mu m and 0.5 mu m after concentrating to obtain the ultra-high purity silica sol with the surface provided with the convex structure and the total metal ion content of which is less than 1ppm.
Example 3
Taking 500g of methanol and 1500g of water, adjusting the pH to 9 by ammonia water, and fully stirring and uniformly mixing to obtain A 1 Mixing 150g of methyl orthosilicate and 750g of methanol uniformly to obtain solution B 1 Liquid, at 40 ℃, adding the liquid B1 into the liquid A at a feeding rate of 22.5ml/min 1 In the liquid, the stirring speed is 400r/min. After the feeding is finished, the mixture is aged for 1 hour to obtain seed crystal solution B with the primary particle diameter of 10nm 2 . Taking 300g of water and 300g of methanol, adjusting the pH to 8.5 by ammonia water to obtain a bottoming liquid A 2 Then adding 0.03g of malic acid, mixing uniformly, and adding B at 60 DEG C 2 Drop-wise adding to A at a rate of 6ml/min 2 In the stirring rotation speed400r/min, during which the liquid level was maintained constant. And after the feeding is finished, continuing to age for 3 hours to obtain the initial silica sol. Adopting a constant liquid level heating concentration mode, adding water while evaporating until the methanol content of the silica sol is reduced to below 1000ppm, concentrating to 20%, and filtering by adopting a filter element with a filtering grade of 1 mu m and 0.5 mu m after concentrating to obtain the ultra-high purity silica sol with the surface provided with the convex structure and the total metal ion content of which is less than 1ppm.
Example 4
2000g of water is taken, the pH value is adjusted to 11 by ammonia water, and the water is fully stirred and mixed uniformly to be used as A 1 Mixing 150g of methyl orthosilicate and 150g of methanol uniformly to obtain solution B 1 Liquid, at 35 ℃, mix B 1 The liquid was added to A at a feed rate of 7.5ml/min 1 In the liquid, the stirring speed is 350r/min. After the feeding is finished, the mixture is aged for 1 hour to obtain seed crystal solution B with the primary particle diameter of 8nm 2 . 600g of water was taken and the pH was adjusted to 10 with ammonia water as a primer solution A 2 Then adding 1.2g of formic acid, mixing uniformly, and adding B at 90 DEG C 2 Drop-wise adding to A at a rate of 1.5ml/min 2 The stirring speed was 350r/min, and the liquid level was maintained constant during this period. And after the feeding is finished, continuing to age for 3 hours to obtain the initial silica sol. Adopting a constant liquid level heating concentration mode, adding water while evaporating until the methanol content of the silica sol is reduced to below 1000ppm, concentrating to 20%, and filtering by adopting a filter element with a filtering grade of 1 mu m and 0.5 mu m after concentrating to obtain the ultra-high purity silica sol with the surface provided with the convex structure and the total metal ion content of which is less than 1ppm.
Example 5
1000g of ethanol and 1000g of water are taken, the pH value is adjusted to 11 by tetramethyl ammonium hydroxide, and the mixture is fully stirred and uniformly mixed to be used as A 1 Mixing 100g of ethyl orthosilicate and 1000g of ethanol uniformly to obtain solution B 1 Liquid, at 50 ℃, B is added 1 The liquid was added to A at a feed rate of 2ml/min 1 In the liquid, the stirring speed is 500r/min. After the feeding is finished, the mixture is aged for 1 hour to obtain seed crystal solution B with the primary particle diameter of 10nm 2 . 600g of water was taken and the pH was adjusted to 8.5 with tetramethylammonium hydroxide as primer solution A 2 Then addUniformly mixing 0.8g of malic acid, and adding B at 90 DEG C 2 Drop-wise adding to A at a rate of 8ml/min 2 The stirring speed was 500r/min, and the liquid level was maintained constant during this period. And after the feeding is finished, continuing to age for 3 hours to obtain the initial silica sol. Adopting a constant liquid level heating concentration mode, adding water while evaporating until the ethanol content of the silica sol is reduced to below 1000ppm, concentrating to 20%, and filtering by adopting a filter element with a filtering grade of 1 mu m and 0.5 mu m after concentrating to obtain the ultra-high purity silica sol with the surface provided with the convex structure and the total metal ion content of which is less than 1ppm.
Comparative example 1
Taking 1500g of methanol and 500g of water, adjusting the pH to 10 by ammonia water, and fully stirring and uniformly mixing to obtain A 1 Mixing 50g of methyl orthosilicate and 150g of methanol uniformly to obtain solution B 1 Liquid, at 25 ℃, mix B 1 The liquid was added to A at a feed rate of 5ml/min 1 In the liquid, the stirring speed is 500r/min. After the feeding is finished, the mixture is aged for 1 hour, and the initial silica sol with the secondary particle size of 70nm is obtained. Adopting a constant liquid level heating concentration mode, adding water while evaporating until the methanol content of the silica sol is reduced to below 1000ppm, concentrating to 20%, and filtering by adopting a filter element with a filtering grade of 1 mu m and 0.5 mu m after concentrating to obtain the ultra-high purity silica sol with the total metal ion content of less than 1ppm and smooth surface and without a convex structure.
Comparative example 2
Taking 1500g of methanol and 500g of water, adjusting the pH to 10 by ammonia water, and fully stirring and uniformly mixing to obtain A 1 Mixing 150g of methyl orthosilicate and 50g of methanol uniformly to obtain solution B 1 Liquid, at 50 ℃, B is added 1 The liquid was added to A at a feed rate of 5ml/min 1 In the liquid, the stirring speed is 500r/min. After the feeding is finished, the mixture is aged for 1 hour to obtain seed crystal solution B with the primary particle diameter of 10nm 2 . 600g of water was taken and pH was adjusted to 10 with ammonia water as a primer solution A 2 At 80 ℃, B is treated with 2 Drop-wise adding to A at a rate of 2ml/min 2 The stirring speed was 500r/min, and the liquid level was maintained constant during this period. And after the feeding is finished, continuing to age for 3 hours to obtain the initial silica sol. Adopts a constant liquid level heating concentration modeAdding water and evaporating until the methanol content of the silica sol is reduced to below 1000ppm, concentrating to 20%, and filtering with filter elements of 1 μm and 0.5 μm filter grade to obtain silica sol with particle size without surface protrusion structure.
Comparative example 3
Taking 1500g of methanol and 500g of water, adjusting the pH to 10 by ammonia water, and fully stirring and uniformly mixing to obtain A 1 Mixing 150g of methyl orthosilicate and 50g of methanol uniformly to obtain solution B 1 Liquid, at 50 ℃, B is added 1 The liquid was added to A at a feed rate of 5ml/min 1 In the liquid, the stirring speed is 500r/min. After the feeding is finished, the mixture is aged for 1 hour to obtain seed crystal solution B with primary particle size 2 . Will B 2 As a primer solution, 0.6g of citric acid was added and mixed well. 600g of water was taken and the pH was adjusted to 10 with ammonia as A 2 At 80 ℃, A is prepared 2 Drop-wise adding to B at a rate of 2ml/min 2 The stirring speed was 500r/min, and the liquid level was maintained constant during this period. And after the feeding is finished, continuing to age for 3 hours to obtain the initial silica sol. Adopting a constant liquid level heating concentration mode, adding water while evaporating until the methanol content of the silica sol is reduced to below 1000ppm, concentrating to 20%, and filtering by adopting filter cores with filtering grades of 1 mu m and 0.5 mu m after concentrating, wherein the surfaces of the obtained silica sol particles are not provided with a convex structure.
The metal impurity content of the silica sol prepared in the embodiment of the invention is shown in the following table:
Na/ppb K/ppb Ca/ppb Mg/ppb Fe/ppb Al/ppb
example 1 55 35 29 11 2 0.3
Example 2 62 37 25 15 3 0.7
Example 3 47 31 35 17 5 0.6
Example 4 70 29 32 16 4 0.9
Example 5 54 30 27 17 1 1
The difference between comparative example 1 and example 1 is only that the preparation processes of comparative example 1 and example 1 are different, the process of secondary growth does not exist in comparative example 1, it can be seen from fig. 1 and 2 that there is a more remarkable contrast change on the surface of the particles of example 1, and the surface of the particles of comparative example 1 is smoother. The difference between comparative example 2 and example 1 is only that no organic acid is added during the growth in comparative example 2, and since no organic acid is added, there is a large repulsive force on the surfaces of small particles, and the probability of contact between particles is small, the primary particle size of the silica sol prepared in comparative example 2 is less different from the particle size of seed particles thereof. The difference between comparative example 3 and example 1 is only that example 1 uses an alkali solution as a primer solution, a seed solution as a silicon source, and comparative example 3 uses a seed solution as a primer solution and an alkali aqueous solution as an additive, as shown in fig. 3, it is also impossible to obtain a silica sol having a convex structure on the surface.
The applicant states that the detailed method of the present invention is illustrated by the above examples, but the present invention is not limited to the detailed method described above, i.e. it does not mean that the present invention must be practiced in dependence upon the detailed method described above. It should be apparent to those skilled in the art that any modification of the present invention, equivalent substitution of raw materials for the product of the present invention, addition of auxiliary components, selection of specific modes, etc., falls within the scope of the present invention and the scope of disclosure.

Claims (10)

1. The preparation method of the ultra-high purity silica sol with the raised structure on the surface is characterized by comprising the following steps:
1) Preparation of seed crystal: mixing alcohol and deionized water, and adjusting pH with alkali to obtain base solution A 1 Then, under stirring, a mixture of alkoxysilane and alcohol was used as the silicon source B 1 With silicon source B 1 To the priming solution A for feeding 1 Obtaining seed crystal solution B 2 ；
2) And (3) secondary growth: mixing alcohol, alkali and water as base solution A 2 Adjustment A 2 At pH of priming solution A 2 Adding acidic compound into the solution A 2 Heating and stirring the seed crystal solution B in the step 1) 2 To the priming solution A for feeding 2 Maintaining the liquid level constant during the process, and continuing aging after the material is fed to obtain initial silica sol;
3) Solvent displacement and concentration: displacing alcohol in the initial silica sol with ultrapure water, and concentrating to 20% or more;
4) And (3) filtering: and filtering the concentrated silica sol to remove large particles to obtain the ultra-high purity silica sol with the surface provided with the convex structure, wherein the mass fraction of the ultra-high purity silica sol is more than 20%.
2. The preparation method according to claim 1, wherein the alkoxysilane in step 1) is one or more of tetramethoxysilane, tetraethoxysilane and tetrapropoxysilane, preferably tetramethoxysilane; and/or
The alcohol is small molecular alcohol of C1-C6, preferably one or more of methanol, ethanol, glycol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol and 1-hexanol, more preferably methanol or ethanol; and/or
The resistivity of the deionized water is more than 15MΩ & cm, preferably more than 18MΩ & cm; and/or
The alkali is at least any one of alkali metal hydroxide, ammonia water, organic amine or guanidine compound; preferably, the alkali metal hydroxide is selected from at least any one of potassium hydroxide, sodium hydroxide and lithium hydroxide, the organic amine is selected from at least any one of ethylenediamine, triethanolamine and tetramethyl ammonium hydroxide, and the guanidine compound is selected from at least any one of tetramethyl guanidine, trimethyl guanidine and guanidine carbonate; more preferably, the base catalyst is selected from any one of ammonia, ethylenediamine or tetramethylammonium hydroxide;
preferably, step 1) the priming solution A 1 The mass ratio of the medium alcohol to the water is 0-10:1, preferably 0 to 5:1, a step of; adjusting the pH to 7.5-11, preferably 9-11, with a base; and/or
The silicon source B 1 The mass ratio of the medium alcohol to the alkoxy silane is 1:3-10:1;
more preferably, silicon source B 1 With priming solution A 1 The volume ratio of (2) is 1:20-5:1.
3. The method according to claim 1, wherein the stirring conditions in step 1) are at a temperature of 10-100 ℃, preferably 10-60 ℃, for a stirring time of 0.5-3 hours, preferably 0.5-1 hour, and a stirring speed of 200-1000r/min, preferably 200-500r/min; and/or
The silicon source B in step 1) 1 The feeding time of (2) is 10min-10h, preferably 10min-5h.
4. The method according to claim 1, wherein the base in step 2) is at least one selected from the group consisting of alkali metal hydroxides, aqueous ammonia, organic amines and guanidine compounds;
preferably, the alkali metal hydroxide is at least any one selected from potassium hydroxide, sodium hydroxide and lithium hydroxide; and/or
The organic amine is at least any one selected from ethylenediamine, triethanolamine and tetramethyl ammonium hydroxide; and/or
The guanidine compound is at least one selected from tetramethylguanidine, trimethylguanidine and guanidine carbonate;
more preferably, the base catalyst is selected from any one of ammonia, ethylenediamine or tetramethylammonium hydroxide;
further preferably, the priming solution A in step 2) 2 The pH of (2) is between 8 and 11, preferably between 8 and 10; and/or
Priming as described in step 2)Liquid A 2 With seed solution B 2 The volume ratio of (1): 10-1:1, preferably 1:10-1:5.
5. the method according to claim 1 or 4, wherein the acidic compound in step 2) is selected from one or more of an inorganic acid, an organic acid, and an ammonium salt thereof;
preferably, the organic acid is selected from one or more of formic acid, acetic acid, oxalic acid, malic acid, citric acid, tartaric acid, lactic acid, gluconic acid, ethylenediamine tetraacetic acid, fumaric acid and methanesulfonic acid; and/or
The inorganic acid is one or more selected from hydrochloric acid, phosphoric acid, sulfuric acid, nitric acid and boric acid; and/or
The ammonium salt is selected from one or more of inorganic acid ammonium or organic acid ammonium corresponding to the inorganic acid or the organic acid;
more preferably, the acidic compound is added in an amount of 500ppm to 5wt%, preferably 500ppm to 2wt%, of the alkoxysilane added in terms of silica mass.
6. The process according to claim 5, wherein the stirring conditions in step 2) are 20 to 100℃and the stirring speed is 200 to 1000r/min, and the seed solution B 2 The feeding speed of the (C) is 1-10ml/min;
preferably, the temperature is 50-90 ℃, the stirring speed is 200-500r/min, and the seed crystal solution B 2 The feed rate of (2) is 1.5-8ml/min.
7. The process according to claim 1, wherein the solvent is replaced in step 3) by adding ultrapure water while heating, evaporating the solvent from the water, or
Concentrating while supplementing ultrapure water by ultrafiltration until the solvent content in the silica sol is reduced to below 200ppm, preferably below 100 ppm;
preferably, in the step 3), vacuum heating concentration or ultrafiltration membrane concentration is adopted for concentration, and the mass fraction of the silica sol is concentrated to more than 20%.
8. The preparation method according to claim 1, wherein the filter element made of PFA or PP is adopted in the step 4), and two-stage or three-stage filtration is adopted, wherein the filtration precision is 0.1 μm-5 μm.
9. The ultra-high purity silica sol having a raised structure on the surface thereof prepared by the method of any one of claims 1 to 8, preferably having a total metal impurity content of less than 1ppm.
10. Use of the ultra-high purity silica sol with a raised structure on the surface prepared by the preparation method according to any one of claims 1 to 8 or the ultra-high purity silica sol with a raised structure on the surface according to claim 9 in CMP polishing.
CN202410001203.6A 2024-01-02 2024-01-02 Ultra-high purity silica sol with surface provided with raised structures, preparation method and application thereof Pending CN117842999A (en)

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