A monodisperse colloidal silicon dioxide with controllable particle size and its preparation method and application
By mixing silica particles with ultrapure water under stirring conditions, and heating and adding alkyl silicate hydrolysate dropwise, monodispersed and controllable particle size colloidal silica is prepared, which solves the problem of difficult preparation of colloidal silica in the prior art, and realizes colloidal silica with uniform particle size and regular morphology, which is suitable for polishing liquid abrasive particles and reduces the preparation cost.
Patent Information
- Application Number
- CN202411945340.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-27
- Publication Date
- 2025-04-04
AI Technical Summary
The prior art is difficult to effectively prepare monodispersed and controllable colloidal silica, and the preparation process is complex, the cost is high, and the particle size and morphology are difficult to regulate.
By mixing silica particles with ultrapure water under stirring conditions, adjusting the pH value to form a mother liquor, then heating to a reflux state, alkyl silicate hydrolysate dropwise at a uniform speed, and adding alkaline catalyst to maintain the pH value between 7 and 10, heating and concentration, monodispersed and controlled particle size colloidal silica is prepared.
The monodispersibility and controllable particle size of colloidal silica are achieved, with uniform particle size, regular morphology, moderate hardness, good stability and dispersion. It is suitable for CMP polishing liquid abrasive particles, and is simple to operate and low cost, which is suitable for large-scale production.
Smart Images
Figure CN119750593A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of polishing liquid, and in particular to monodisperse colloidal silicon dioxide with controllable particle size, and a preparation method and application thereof. Background Art
[0002] Chemical mechanical polishing (CMP) uses chemical action, grinding action and adsorption effect to achieve the purpose of smoothing the substrate surface. Based on this, CMP polishing liquid has gradually been developed for wafer surface flattening in semiconductor manufacturing. CMP polishing liquid is usually composed of a variety of chemical components such as abrasives, oxidants, complexing agents, surfactants, corrosion inhibitors, pH regulators, etc. These components act together on the wafer surface during the polishing process. Through the dual effects of chemical corrosion and mechanical grinding, the excess material on the wafer surface is removed to achieve the purpose of flattening, smoothing and removing the damaged layer. As the most important component in CMP polishing liquid, the grinding performance of the polishing liquid is determined by factors such as hardness, particle size, shape and solid content of the abrasive particles. Among them, silicon dioxide has become the first choice for CMP polishing liquid abrasive particles due to its inherent properties such as moderate hardness, good stability and good dispersibility.
[0003] At present, various methods for preparing small-sized colloidal silica have been reported, mainly including ion exchange method, one-step dissolution method of elemental silicon and silanol hydrolysis method. These methods often have high preparation costs, complex preparation processes, and properties such as particle size, morphology and purity cannot be effectively regulated. At the same time, in the selection of alkaline catalysts, most of them choose ammonia water as the alkaline catalyst, and ammonia water is easy to volatilize, which increases the rate of decrease of the pH of the reaction system, and the rapid change of pH directly affects the hydrolysis-condensation rate of the silicon source. Since the hydrolysis rate of the silicon source determines the size of the nanoparticles, and the condensation rate determines the nucleation of the nanoparticles, the rapid decrease of the pH of the reaction system leads to different sizes of colloidal particles and irregular morphology. Therefore, the prior art is in urgent need of a method for preparing monodisperse colloidal silica with controllable particle size. Summary of the invention
[0004] The purpose of the present invention is to provide a monodisperse colloidal silica with controllable particle size, and a preparation method and application thereof. The colloidal silica prepared by the method provided by the present invention is monodisperse, has controllable particle size, uniform particle size, regular morphology, simple operation and low cost.
[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:
[0006] The present invention provides a method for preparing monodisperse colloidal silicon dioxide with controllable particle size, comprising the following steps:
[0007] (1) mixing silica particles with ultrapure water under stirring conditions, and adjusting the pH to obtain a mother solution;
[0008] (2) The mother liquor obtained in step (1) is heated to reflux, and the alkyl silicate hydrolyzate is added dropwise at a uniform rate, and an alkaline catalyst is added to maintain the pH value of the reaction liquid at 7 to 10, and the reaction liquid is concentrated by heating to obtain monodisperse colloidal silica with controllable particle size.
[0009] Preferably, the particle size of the silicon dioxide particles in step (1) is 6 to 30 nm.
[0010] Preferably, the pH value of the mother liquor in step (1) is 10-12.
[0011] Preferably, the alkyl silicate in the alkyl silicate hydrolyzate in step (2) is at least one of methyl orthosilicate and ethyl orthosilicate.
[0012] Preferably, the concentration of silicon dioxide in the alkyl silicate hydrolyzate in step (2) is 1 to 12 wt %.
[0013] Preferably, in step (2), the dropping speed of the alkyl silicate hydrolyzate is 0.7 to 41 g silicon dioxide / hour / kg mother liquor, and the injection time of the alkyl silicate hydrolyzate is 700 to 2000 min.
[0014] Preferably, the alkaline catalyst in step (2) is at least one of tetramethylammonium hydroxide, triethanolamine and ammonia.
[0015] Preferably, the pH value of the reaction solution in step (2) is maintained at 8-9.
[0016] The present invention also provides monodisperse colloidal silicon dioxide with controllable particle size prepared by the preparation method described in the above technical solution, wherein the average primary particle size of the monodisperse colloidal silicon dioxide with controllable particle size is 20 to 30 nm.
[0017] The present invention also provides the use of the monodisperse colloidal silicon dioxide with controllable particle size described in the above technical solution in polishing.
[0018] The present invention provides a monodisperse colloidal silica with controllable particle size. First, silica particles are mixed with ultrapure water under stirring conditions, and the pH is adjusted to obtain a mother liquor; then the mother liquor is heated to a reflux state, and an alkyl silicate hydrolyzate is added dropwise at a uniform speed to control the growth rate of silica particles. The pre-preparation of the alkyl silicate hydrolyzate enables the alkyl silicate to grow particles at a higher temperature, thereby obtaining silica particles with better monodispersity. At the same time, an alkaline catalyst is added to maintain the pH value of the reaction solution at 7 to 10, promote further hydrolysis of the alkyl silicate, and prevent the reaction solution from gelling, thereby ensuring the normal progress of the hydrolysis reaction. The alcohol is removed by heating and concentration to obtain monodisperse colloidal silica with controllable particle size. The colloidal silica prepared by the method provided by the present invention has uniform particle size, regular morphology, moderate hardness, good stability and good dispersibility, and can be used as a CMP polishing liquid grinding particle. The method of the present invention is simple to operate, low in cost, and suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 This is a TEM image of the monodisperse colloidal silica with controllable particle size prepared in Example 3 of the present invention. DETAILED DESCRIPTION
[0020] The present invention provides a method for preparing monodisperse colloidal silicon dioxide with controllable particle size, comprising the following steps:
[0021] (1) mixing silica particles with ultrapure water under stirring conditions, and adjusting the pH to obtain a mother solution;
[0022] (2) The mother liquor obtained in step (1) is heated to reflux, and the alkyl silicate hydrolyzate is added dropwise at a uniform rate, and an alkaline catalyst is added to maintain the pH value of the reaction liquid at 7 to 10, and the reaction liquid is concentrated by heating to obtain monodisperse colloidal silica with controllable particle size.
[0023] In the present invention, unless otherwise specified, the raw materials used are conventional commercial products in the art.
[0024] The present invention mixes silicon dioxide particles with ultrapure water under stirring conditions, and obtains a mother solution by adjusting the pH.
[0025] The present invention has no particular limitation on the stirring method, and any technical solution known in the art may be used.
[0026] In the present invention, the particle size of the silicon dioxide particles is preferably 6 to 30 nm, more preferably 10 to 20 nm. The present invention controls the particle size of the silicon dioxide particles within the above range to ensure that at a certain injection speed of the alkyl silicate hydrolyzate, the newly generated silicon dioxide particles grow as completely as possible on the surface of the seed particles, which is conducive to obtaining monodisperse colloidal silicon dioxide with controllable particle size.
[0027] In the present invention, the mass ratio of the silica particles to ultrapure water is preferably (0.5-3):1, and more preferably (1-2):1.
[0028] In the present invention, the pH value of the mother liquor is preferably 10 to 12. In the present invention, the reagent used to adjust the pH is preferably an alkaline catalyst; the alkaline catalyst is preferably at least one of tetramethylammonium hydroxide, 3-ethoxypropylamine, triethylamine and dipropylamine. The present invention adjusts the hydrolysis rate of the alkyl silicate by controlling the pH value of the mother liquor to control the growth rate of the silica particles, thereby facilitating the acquisition of monodisperse colloidal silica with controllable particle size.
[0029] After obtaining the mother liquor, the present invention heats the mother liquor to a reflux state, uniformly drops the alkyl silicate hydrolyzate, and simultaneously adds an alkaline catalyst to maintain the pH value of the reaction liquid at 7-10, and concentrates the reaction liquid by heating to obtain colloidal silicon dioxide.
[0030] In the present invention, the alkyl silicate in the alkyl silicate hydrolyzate is preferably at least one of methyl orthosilicate and ethyl orthosilicate.
[0031] In the present invention, the method for preparing the alkyl silicate hydrolyzate preferably comprises:
[0032] At room temperature and under stirring conditions, alkyl silicate is added to ultrapure water, and after the reaction solution gradually changes into a clear state, a hydrolysis reaction is carried out for 1 to 2 hours to obtain an alkyl silicate hydrolyzate.
[0033] In the present invention, the mass ratio of the ultrapure water to the alkyl silicate is preferably (10-14):1, more preferably 12:1.
[0034] In the present invention, the concentration of silicon dioxide in the alkyl silicate hydrolyzate is preferably 1 to 12 wt %, more preferably 3 to 9 wt %. The present invention prevents the alkyl silicate hydrolyzate from gelling and ensures the normal progress of the hydrolysis reaction by controlling the concentration of silicon dioxide in the alkyl silicate hydrolyzate within the above range.
[0035] In the present invention, the dripping speed of the alkyl silicate hydrolyzate is preferably 0.7-41 g silica / hour / kg mother liquor. In the present invention, the injection time of the alkyl silicate hydrolyzate is preferably 700-2000 min, more preferably 720-1800 min. The present invention adjusts the hydrolysis rate of the alkyl silicate by controlling the dripping speed and injection time of the alkyl silicate hydrolyzate to control the growth rate of the silica particles, and combines the principle of economy.
[0036] In the present invention, the alkaline catalyst is preferably at least one of tetramethylammonium hydroxide, triethanolamine and ammonia.
[0037] In the present invention, the pH value of the reaction solution is preferably maintained at 8 to 9. The present invention controls the pH value of the reaction solution to avoid gelation, thereby ensuring that the hydrolysis reaction proceeds normally under the condition that the alkyl silicate is completely hydrolyzed.
[0038] In the present invention, the heating and concentration method is preferably distillation. The present invention has no special limitation on the distillation method, and the purpose of concentration and alcohol removal can be achieved by using technical solutions well known in the art.
[0039] The present invention also provides monodisperse colloidal silicon dioxide with controllable particle size prepared by the preparation method described in the above technical solution.
[0040] In the present invention, the average primary particle size of the monodisperse colloidal silica with controllable particle size is 20 to 30 nm. In the present invention, the average secondary particle size of the monodisperse colloidal silica with controllable particle size is preferably 20 to 40 nm.
[0041] The present invention also provides the use of the monodisperse colloidal silicon dioxide with controllable particle size described in the above technical solution in polishing.
[0042] In the present invention, the monodisperse colloidal silica with controllable particle size is preferably used as abrasive particles in CMP polishing liquid.
[0043] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0044] Example 1
[0045] A method for preparing monodisperse colloidal silicon dioxide with controllable particle size, comprising the following steps:
[0046] (1) Under stirring conditions, 100 g of silica particles with a particle size of 15 nm were added to 100 g of ultrapure water and mixed evenly, and TMAH with a concentration of 25 wt % was added to adjust the pH to obtain a mother solution with a pH value of 10;
[0047] (2) adding the mother liquor into a 3L glass reactor with four ports containing a thermometer, a condenser, a stirrer and an injection port, and continuously heating the mother liquor to a reflux state under stirring, and then dropping TMOS hydrolyzate at a uniform rate, with an injection rate of 9 g silica / h / kg mother liquor, and a continuous injection time of 720 min. Since the TMOS hydrolyzate is weakly acidic, the introduction of the TMOS hydrolyzate will cause the pH of the reaction liquid to decrease. The pH of the reaction liquid needs to be detected every half an hour, and the corresponding TMAH is added to stabilize the pH of the reaction liquid at 8 to obtain a reaction liquid;
[0048] The preparation method of the TMOS hydrolyzate is as follows: 34.2 g of TMOS is weighed in a beaker, and 415.8 g of ultrapure water is weighed in another beaker; 34.2 g of TMOS weighed in advance is gradually added to the weighed 415.8 g of ultrapure water under room temperature and stirring, and after TMOS is added to the ultrapure water, the solution immediately becomes turbid, and after 15 minutes, the solution gradually becomes clear, and the hydrolysis reaction is continued for 1 hour to obtain a TMOS hydrolyzate with a silicon dioxide content of 3 wt%;
[0049] The mass ratio of the ultrapure water to the alkyl silicate is 12:1;
[0050] 500 mL of the reaction solution was added to a 1 L 2 L glass reactor with four ports including a thermometer, a condenser, a stirrer and an injection port, and heated and concentrated. During the concentration process, the same volume of the reaction solution as the fraction was added to maintain a constant liquid level, and finally monodisperse colloidal silica with a silica content of 12% and controllable particle size was obtained.
[0051] Example 2
[0052] A method for preparing monodisperse colloidal silicon dioxide with controllable particle size, comprising the following steps:
[0053] According to the steps of Example 1, a mother solution and a TMOS hydrolyzate were prepared respectively;
[0054] The mother liquor is added into a four-mouth 3L glass reactor containing a thermometer, a condenser, a stirrer and an injection port. Under stirring, the mother liquor is continuously heated to a reflux state, and TMOS hydrolyzate is added dropwise at a uniform rate. The injection rate of the TMOS hydrolyzate is 7.2 g silica / h / kg mother liquor, and the continuous injection time is 900 min. Since the TMOS hydrolyzate is weakly acidic, the introduction of the TMOS hydrolyzate will cause the pH of the reaction liquid to decrease. The pH of the reaction liquid needs to be detected every half an hour, and the corresponding TMAH is added to stabilize the pH of the reaction liquid at 8 to obtain a reaction liquid;
[0055] Then, the reaction solution was concentrated and the alcohol was removed according to the steps of Example 1 to obtain monodisperse colloidal silicon dioxide with controllable particle size.
[0056] Example 3
[0057] Monodisperse colloidal silica with controllable particle size was prepared according to the method of Example 1, except that the injection rate of the TMOS hydrolyzate was 5.4 g silica / h / kg mother liquor, and the injection time of the TMOS hydrolyzate was 1200 min.
[0058] Figure 1 This is a TEM image of the monodisperse colloidal silica with controllable particle size prepared in Example 3 of the present invention. Figure 1 It can be seen that the colloidal silicon dioxide prepared in Example 3 has good dispersibility and uniform particle size.
[0059] Example 4
[0060] Monodisperse colloidal silica with controllable particle size was prepared according to the method of Example 1, except that the injection rate of the TMOS hydrolyzate was 3.6 g silica / h / kg mother liquor, and the injection time of the TMOS hydrolyzate was 1800 min.
[0061] The monodisperse colloidal silica with controllable particle size prepared in Example 3 was detected by inductively coupled plasma mass spectrometry, and the alkali metal impurity content was less than 300 ppb, and the heavy metal impurity content was less than 100 ppb. The properties of the mother solution and TMOS hydrolyzate prepared in Examples 1 to 4, and the monodisperse colloidal silica with controllable particle size are shown in Table 1.
[0062] In Table 1, the injection rate of TMOS hydrolyzate is calculated based on the mass of TMOS hydrolyzate added per minute; the specific gravity (20 / 4°C) is measured by a hydrometer, the viscosity (mPa·s) is measured by a viscometer, the PDI is measured by a nanoparticle size and Zeta potential analyzer, and the BET (m 2 / g);
[0063] The method for determining the average primary particle size is as follows: drying the corresponding colloidal silica obtained at 140°C for 24 hours, and then calcining at 800°C for 1 hour to obtain a sample; using the prepared sample to determine BET, and using the value of 2727 / BET as the average primary particle size of the silica particles in the colloidal silica;
[0064] Average secondary particle size: measured by nanoparticle size and Zeta potential analyzer (DLS);
[0065] Aggregation ratio: The ratio of the average secondary particle size to the average primary particle size is taken as the aggregation ratio.
[0066] The mother solution and TMOS hydrolyzate prepared in Examples 1 to 4, and the performance of the monodisperse colloidal silica with controllable particle size
[0067]
[0068]
[0069] Example 5
[0070] According to the method of Example 3, monodisperse colloidal silicon dioxide with controllable particle size was prepared, except that:
[0071] The preparation method of the TMOS hydrolyzate is as follows: 60.0 g of TMOS is weighed in a beaker, and 415.8 g of ultrapure water is weighed in another beaker; 60.0 g of TMOS weighed in advance is gradually added to the weighed 415.8 g of ultrapure water under room temperature and stirring. After TMOS is added to the ultrapure water, the solution immediately becomes turbid. After 15 minutes, the solution gradually becomes clear. After the hydrolysis reaction is continued for 1 hour, a TMOS hydrolyzate with a silicon dioxide content of 5 wt% is obtained.
[0072] Example 6
[0073] According to the method of Example 3, monodisperse colloidal silicon dioxide with controllable particle size was prepared, except that:
[0074] The preparation method of the TMOS hydrolyzate is as follows: 90.0 g of TMOS is weighed in a beaker, and 415.8 g of ultrapure water is weighed in another beaker; 90.0 g of TMOS weighed in advance is gradually added to the weighed 415.8 g of ultrapure water under room temperature and stirring. After TMOS is added to the ultrapure water, the solution immediately becomes turbid. After 15 minutes, the solution gradually becomes clear. After the hydrolysis reaction is continued for 1 hour, a TMOS hydrolyzate with a silicon dioxide content of 7 wt% is obtained.
[0075] Example 7
[0076] According to the method of Example 3, monodisperse colloidal silicon dioxide with controllable particle size was prepared, except that:
[0077] The preparation method of the TMOS hydrolyzate is as follows: 124.0 g of TMOS is weighed in a beaker, and 415.8 g of ultrapure water is weighed in another beaker; 124.0 g of TMOS weighed in advance is gradually added to the weighed 415.8 g of ultrapure water under room temperature and stirring. After TMOS is added to the ultrapure water, the solution immediately becomes turbid. After 15 minutes, the solution gradually becomes clear. After the hydrolysis reaction is continued for 1 hour, a TMOS hydrolyzate with a silicon dioxide content of 9 wt% is obtained.
[0078] The properties of the mother solutions and TMOS hydrolyzate prepared in Examples 5 to 7, as well as the monodisperse colloidal silica with controllable particle size, were measured by the same detection method as in Table 1, as shown in Table 2.
[0079] Performance of the mother solution and TMOS hydrolyzate prepared in Examples 3 and 5-7, and the monodisperse colloidal silica with controllable particle size
[0080]
[0081]
[0082] It can be seen from the above test results that as the injection speed of the TMOS hydrolyzate gradually decreases and the injection time gradually prolongs, the primary particle size of the silica particles gradually increases, indicating that the lower injection speed and longer injection time of the TMOS hydrolyzate are more conducive to the growth of silica particles. In addition, as the silica content in the TMOS hydrolyzate gradually increases, the primary particle size and secondary particle size of the silica particles both increase slightly, indicating that the TMOS hydrolyzate with a higher silica content is more conducive to the growth of silica particles. However, from the perspective of preventing the TMOS hydrolyzate from gelling, the TMOS hydrolyzate with a lower silica content is more suitable for the preparation of colloidal silica particles. It can be seen that the particle size of the prepared colloidal silica can be controlled using the method of the present invention, and the dispersibility is good.
[0083] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A method for preparing monodisperse colloidal silicon dioxide with controllable particle size, characterized in that: The following steps are involved: (1) mixing silica particles with ultrapure water under stirring conditions, and adjusting the pH to obtain a mother solution; (2) The mother liquor obtained in step (1) is heated to reflux, and the alkyl silicate hydrolyzate is added dropwise at a uniform rate, and an alkaline catalyst is added to maintain the pH value of the reaction liquid at 7 to 10, and the reaction liquid is concentrated by heating to obtain monodisperse colloidal silica with controllable particle size.
2. The preparation method according to claim 1, characterized in that: The particle size of the silicon dioxide particles in step (1) is 6 to 30 nm.
3. The preparation method according to claim 1, characterized in that: The pH value of the mother liquor in step (1) is 10-12.
4. The preparation method according to claim 1, characterized in that: In the step (2), the alkyl silicate in the alkyl silicate hydrolyzate is at least one of methyl orthosilicate and ethyl orthosilicate.
5. The preparation method according to claim 1, characterized in that: The concentration of silicon dioxide in the hydrolyzate of alkyl silicate in step (2) is 1 to 12 wt %.
6. The preparation method according to claim 1, characterized in that: In the step (2), the dropping speed of the alkyl silicate hydrolyzate is 0.7 to 41 g silicon dioxide / hour / kg mother liquor, and the injection time of the alkyl silicate hydrolyzate is 700 to 2000 min.
7. The preparation method according to claim 1, characterized in that: In the step (2), the alkaline catalyst is at least one of tetramethylammonium hydroxide, triethanolamine and ammonia.
8. The preparation method according to claim 1, characterized in that: In the step (2), the pH value of the reaction solution is maintained at 8-9.
9. The monodisperse colloidal silicon dioxide with controllable particle size prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The average primary particle size of the monodisperse colloidal silicon dioxide with controllable particle size is 20 to 30 nm.
10. Use of the monodisperse colloidal silicon dioxide with controllable particle size according to claim 9 in polishing.