Colloidal silicon dioxide with controllable association degree as well as preparation method and application of colloidal silicon dioxide

Abstract

The invention provides colloidal silicon dioxide with controllable association degree as well as a preparation method and application thereof, and belongs to the technical field of polishing solutions. The method comprises the following steps: firstly, heating ultrapure water to a reflux state, dropwise adding alkyl silicate hydrolysate until the pH value of the solution is acidic, curing to obtain a mixed solution A, continuously dropwise adding the alkyl silicate hydrolysate until particles grow to a target particle size, and heating and concentrating to remove alcohol to obtain colloidal silicon dioxide with controllable association degree. The prepared colloidal silicon dioxide is wide in association degree adjustable range, good in stability and good in dispersity and can serve as grinding particles of a CMP polishing solution, and the method is easy to operate, low in cost and suitable for large-scale production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polishing liquid, in particular to a colloidal silicon dioxide with controllable association degree, and a preparation method and application thereof. BACKGROUND

[0002] As the core of chemical mechanical polishing (CMP) technology, the polishing liquid mainly includes abrasive particles, surfactants, oxidizing agents, corrosion inhibitors, complexing agents and buffering agents, etc. Among them, the abrasive particles are the core component of the polishing liquid, which removes the surface material softened by chemical reaction through micro-cutting and rolling friction. Among numerous abrasive particles, colloidal silicon dioxide is the preferred material for polishing liquid abrasive particles due to its moderate hardness, chemical inertness, high purity, controllable morphology and particle size, etc.

[0003] The balance between "material removal rate" and "surface quality" in the CMP process is closely related to the association degree of colloidal silicon dioxide particles. Low association degree particles, i.e. highly dispersed single spherical particles, have very mild mechanical action, mainly producing rolling and micro-cutting, which can minimize scratches and subsurface damage, and achieve excellent surface quality. High association degree particles, i.e. when multiple primary particles are aggregated together, they form a larger and loosely structured "cluster". This cluster has more actual contact points with the wafer surface under the pressure of the polishing pad, and the internal particles will have a small relative motion, producing stronger micro-shearing and cutting action. Therefore, it is necessary to precisely design and control the association degree of colloidal silicon dioxide to finely adjust the mechanical action strength of the polishing slurry, so as to find the best balance point between removal efficiency and surface perfection. Therefore, there is an urgent need for a method for preparing colloidal silicon dioxide with controllable association degree. SUMMARY

[0004] The present application aims to provide a colloidal silicon dioxide with controllable association degree, and a preparation method and application thereof. The colloidal silicon dioxide prepared by the method provided by the present application has a wide association degree range, high monodispersity and low production cost.

[0005] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions: The present application provides a preparation method of colloidal silicon dioxide with controllable association degree, comprising the following steps: (1) After heating the ultrapure water to reflux state, drop the silicon alkyl ester hydrolysate into the solution to make the pH value acidic, and mature to obtain a mixed solution A; (2) Continue to drop the silicon alkyl ester hydrolysate into the mixed solution A, and add an alkaline catalyst to maintain the pH value of the reaction solution to be alkaline, and concentrate by heating to obtain a colloidal silicon dioxide dispersion.

[0006] Preferably, the alkyl silicate in the alkyl silicate hydrolyzate is at least one selected from the group consisting of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate.

[0007] Preferably, the concentration of silicon dioxide in the alkyl silicate hydrolyzate is 1 wt% to 15 wt%.

[0008] Preferably, the concentration of silicon dioxide in the alkyl silicate hydrolyzate is 3 wt% to 12 wt%.

[0009] Preferably, the dropping speed of the alkyl silicate hydrolyzate in the step (1) and the step (2) is independently 0.5 to 50 g / min.

[0010] Preferably, the dropping speed of the alkyl silicate hydrolyzate in the step (1) and the step (2) is independently 0.5 to 30 g / min.

[0011] Preferably, the alkyl silicate hydrolyzate is dropped at a constant speed in the step (1) and the step (2).

[0012] Preferably, the pH value of the mixed solution A is 3 to 6.9.

[0013] Preferably, the pH value of the mixed solution A is 4.4 to 6.4.

[0014] Preferably, the temperature of the aging is 50 to 100°C.

[0015] Preferably, the temperature of the aging is 55 to 80°C.

[0016] Preferably, the time of the aging is 10 to 300 min.

[0017] Preferably, the time of the aging is 30 to 250 min.

[0018] Preferably, the feeding time of the alkyl silicate hydrolyzate in the step (2) is 500 to 6000 min.

[0019] Preferably, the feeding time of the alkyl silicate hydrolyzate in the step (2) is 1000 to 4000 min.

[0020] Preferably, the mass ratio of the total amount of the ultrapure water and the alkyl silicate hydrolyzate in the step (1) is 1: (0.5 to 15).

[0021] Preferably, the mass ratio of the total amount of the ultrapure water and the alkyl silicate hydrolyzate in the step (1) is 1: (2 to 10).

[0022] The total amount of the alkyl silicate hydrolysis solution is the sum of the amount of the alkyl silicate hydrolysis solution in step (1) and the amount of the alkyl silicate hydrolysis solution in step (2).

[0023] Preferably, the basic catalyst is at least one selected from the group consisting of tetramethylammonium hydroxide, triethanolamine, aqueous ammonia, dipropylamine and triethylamine.

[0024] Preferably, the pH value of the reaction solution in step (2) is 7.5-10.5.

[0025] Preferably, the pH value of the reaction solution in step (2) is 8-10.

[0026] The present application also provides the associated degree controllable colloidal silicon dioxide prepared by the preparation method.

[0027] The present application also provides the application of the associated degree controllable colloidal silicon dioxide in the field of chemical mechanical polishing.

[0028] The present application provides a preparation method of associated degree controllable colloidal silicon dioxide.

[0029] The colloidal silicon dioxide prepared by the method has a wide adjustable range of associated degree and high monodispersity, can be used as a CMP polishing liquid to grind particles, and the method is simple in operation, low in cost and suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 FIG. 3 is a TEM image of the associated degree controllable colloidal silicon dioxide prepared in Example 3 of the present application. DETAILED DESCRIPTION

[0031] The present application provides a preparation method of associated degree controllable colloidal silicon dioxide, which comprises the following steps: (1) after the ultrapure water is heated to a reflux state, the alkyl silicate hydrolysis solution is added at a constant speed until the pH of the solution is in an acidic range, and then the solution is aged for a certain period of time to obtain a mixed solution A.

[0032] (2) continuously adding the alkyl silicate hydrolysis solution to the mixed solution A obtained in the step (1) at a constant rate, while adding a basic catalyst to maintain the pH value of the reaction solution to be alkaline, and then concentrating the solution by heating to obtain a colloidal silica dispersion solution.

[0033] In the present application, the raw materials used are all commercially available products in the art unless otherwise specified.

[0034] In the present application, the alkyl silicate in the alkyl silicate hydrolysis solution is at least one selected from the group consisting of methyl silicate, ethyl silicate and propyl silicate.

[0035] In the present application, the preparation method of the alkyl silicate hydrolysis solution comprises: Under stirring at room temperature, the alkyl silicate is added to the ultrapure water, and the hydrolysis reaction is carried out for 1-2 hours after the reaction solution gradually changes to a clear state to obtain the alkyl silicate hydrolysis solution, wherein the mass ratio of the ultrapure water to the alkyl silicate is (10-14):1, preferably 12:1.

[0036] In the present application, the concentration of the silica in the alkyl silicate hydrolysis solution is 1wt%-15wt%, preferably 3wt%-12wt%. By controlling the concentration of the silica in the alkyl silicate hydrolysis solution in the above range, the present application prevents the gelation of the alkyl silicate hydrolysis solution and ensures the normal progress of the hydrolysis reaction.

[0037] In the present application, the dropping speed of the alkyl silicate hydrolysis solution is 0.5-50g / min, preferably 0.5-30g / min.

[0038] In the present application, the pH value of the mixed solution A is maintained at 3-6.9, preferably 4.4-6.4. By controlling the pH value of the mixed solution A to be acidic, the present application neutralizes the negative charge on the surface of the colloidal particles with hydrogen ions in the acidic solution, compresses the surrounding electric double layer, weakens the electrostatic repulsion between colloids, and makes the van der Waals attraction between colloidal particles dominant, so as to promote the mutual approach and collision between colloidal particles.

[0039] In the present application, the ripening temperature of the mixed solution A is 50-100℃, preferably 55-80℃. In the present application, the ripening time of the mixed solution A is 10-300min, preferably 30-250min. By controlling the ripening temperature and ripening time of the mixed solution A, the present application controls the collision time between colloidal particles to adjust the degree of adhesion between colloidal particles and further adjust the association degree of the formed irregular colloidal particles.

[0040] After the mixed solution A is obtained, the alkali catalyst is added to maintain the pH value of the reaction solution at 7.5-10.5, preferably 8-10, while the alkyl silicate hydrolysis solution is continuously added at a constant speed, and then the colloidal silica dispersion solution is obtained by heating and concentration.

[0041] In the present application, the alkali catalyst is selected from at least one of tetramethylammonium hydroxide, 3-ethoxypropylamine, ammonia, triethylamine, and dipropylamine.

[0042] In the present application, the mass ratio of the total amount of the ultrapure water and the alkyl silicate hydrolysis solution in step (1) is 1:(0.5-15), preferably 1:(2-10). In the present application, the sampling time of the alkyl silicate hydrolysis solution in the preparation of the colloidal silica dispersion solution is 500-6000 min, preferably 1000-4000 min. By controlling the dropping speed and the sampling time of the alkyl silicate hydrolysis solution, the present application adjusts the hydrolysis rate of the alkyl silicate to control the growth rate of the silica particles, and reduces the residual alkyl silicate in the prepared silica particles in combination with the economic principle.

[0043] In the present application, the pH value of the colloidal silica dispersion solution is maintained at 8-10. By controlling the pH value of the colloidal silica dispersion solution, the present application avoids gelation to ensure the normal progress of the hydrolysis reaction under the condition of ensuring complete hydrolysis of the alkyl silicate.

[0044] In the present application, the heating and concentration is performed by distillation. The present application does not have special limitations on the distillation method, and any method known in the art can be used to achieve the purpose of concentration and alcohol removal.

[0045] The present application also provides the colloidal silica with controllable association degree prepared by the preparation method.

[0046] In the present application, the association degree of the colloidal silica with controllable association degree is 1.5-3.0.

[0047] The present application also provides the application of the colloidal silica with controllable association degree in the polishing field.

[0048] In the present application, the colloidal silica with controllable association degree is preferably used as abrasive particles in the CMP polishing liquid.

[0049] The technical solutions in the present application will be described clearly and completely in combination with the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application. Example 1

[0050] A method for preparing a colloidal silica with controllable association degree, comprising the following steps: (1) In a four-port 10L glass reactor with a thermometer, a condenser, a stirrer and a sample inlet, 600g of ultrapure water was added, and under stirring, heated to reflux state, and then TMOS hydrolysate was added at a uniform speed until the pH of the solution was 6.85, and then the TMOS hydrolysate was stopped, and the solution was kept in this state for 30min to ensure that the colloidal particles were fully shaped, the sample was added at a speed of 3.8g / min, and a mixed solution A was obtained; (2) TMOS hydrolysate was continuously added at a uniform speed in the mixed solution A obtained in the step (1), the sample was added at a speed of 3.8g / min, and the sample was continuously added for 1500min, and in addition, the pH of the reaction solution was detected every half hour, and the corresponding triethylamine was added to keep the pH of the solution at 8, and a colloidal silica reaction solution was obtained; The preparation method of the TMOS hydrolysate is as follows: 34.2g of TMOS was weighed in a beaker, and 415.8g of ultrapure water was weighed in another beaker; under the conditions of room temperature and stirring, the pre-weighed 34.2g of TMOS was gradually added to the 415.8g of ultrapure water, and after the TMOS was added to the ultrapure water, the solution immediately became turbid, and after 15min, the solution gradually changed to a clear state, and after the hydrolysis reaction was continued for 1h, a TMOS hydrolysate with a silica content of 3wt% was obtained; The mass ratio of the ultrapure water to the alkyl silicate is 12:1; 500mL of the colloidal silica reaction solution was taken and added to a 1L four-port 2L glass reactor with a thermometer, a condenser, a stirrer and a sample inlet, and heated and concentrated, and during the concentration process, the same volume of the colloidal silica reaction solution as the fraction was added to maintain the constant liquid level, and finally anisotropic colloidal silica with a silica content of 20% was obtained. Example 2

[0051] The colloidal silica with controllable association degree was prepared according to the method of Example 1, and the difference from Example 1 was that in the preparation of the mixed solution A in the step (1), the TMOS hydrolysate was added at a uniform speed until the pH of the solution was 6.65. Example 3

[0052] The colloidal silica with controllable association degree was prepared according to the method of Example 1, and the difference from Example 1 was that in the preparation of the mixed solution A in the step (1), the TMOS hydrolysate was added at a uniform speed until the pH of the solution was 6.45.

[0053] Figure 1 The TEM image of the colloidal silica with controllable association degree prepared in Example 3 of the present application. From the TEM image, it can be seen that the colloidal silica particles are anisotropic and have a large aspect ratio. Figure 1It can be seen that the heteromorphic transformation occurs between the colloidal silica particles with controllable association degree prepared in Example 3. Example 4

[0054] The colloidal silica with controllable association degree was prepared according to the method of Example 1, except that in the preparation of the mixed solution A in step (1), the hydrolysis solution of TMOS was added at a constant speed until the pH of the solution was 6.25. Example 5

[0055] The colloidal silica with controllable association degree was prepared according to the method of Example 1, except that in the preparation of the mixed solution A in step (1), after the addition of the hydrolysis solution of TMOS was stopped, the solution was kept in this state for 90 min. Example 6

[0056] The colloidal silica with controllable association degree was prepared according to the method of Example 1, except that in the preparation of the mixed solution A in step (1), after the addition of the hydrolysis solution of TMOS was stopped, the solution was kept in this state for 180 min.

[0057] The properties of the colloidal silica with controllable association degree prepared in Examples 1-6 are shown in Table 1.

[0058] In Table 1, the specific gravity (20 / 4℃) was detected by using a HM-DS type specific gravity meter, the viscosity (mPa·s) was detected by using a NDJ-1 type viscometer, and the BET (m 2 / g) was detected by using an ASAP 2460 type full-automatic specific surface and porosity analyzer. The average primary particle size was determined by the following method: the obtained colloidal silica was dried at 140℃ for 24h, and then the prepared sample was calcined at 800℃ for 1h; the prepared sample was used to determine the BET, and the value of 2727 / BET was used as the average primary particle size of the silica particles in the colloidal silica; The average secondary particle size was determined by using a Malvern Zetasizer Nano ZS90 type nano particle size and Zeta potential analyzer (DLS); The association degree was the ratio of the average secondary particle size to the average primary particle size.

[0059] Table 1: Properties of the colloidal silica with controllable association degree prepared in Examples 1-6

[0060] The above test results show that the average secondary particle size of the colloidal particles synthesized changes with the change of pH of the mixed solution A and the ripening time, and the association degree also changes. This is because different acid environments provide different amounts of hydrogen ions, and the amount of neutralized negative charges on the surface of the colloidal particles also changes, so the degree of destruction of the double electric layer on the surface of the colloidal particles and the degree of weakening of the electrostatic repulsion are also different, and therefore the degree of abnormality of the crystal nucleus is also different. It can be seen that the method of the present application can successfully prepare colloidal silicon dioxide with controllable association degree.

[0061] The above only describes the preferred embodiments of the present application, and it should be pointed out that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing colloidal silica with controllable association degree, characterized in that, Includes the following steps: (1) After heating the ultrapure water to reflux, add the alkyl silicate hydrolysate dropwise until the pH of the solution is acidic, and then let it mature to obtain mixture A; (2) Continue to add alkyl silicate hydrolysate to the mixture A, and add an alkaline catalyst to maintain the pH of the reaction solution as alkaline. After heating and concentration, a colloidal silica dispersion is obtained.

2. The preparation method according to claim 1, characterized in that, The alkyl silicate hydrolysate is selected from at least one of methyl orthosilicate, ethyl orthosilicate, and propyl orthosilicate. And / or, the concentration of silica in the alkyl silicate hydrolysate is 1wt% to 15wt%, preferably 3wt% to 12wt%.

3. The preparation method according to claim 1 or 2, characterized in that, In steps (1) and (2), the dropping rate of the alkyl silicate hydrolysate is independently 0.5~50 g / min, preferably 0.5~30 g / min.

4. The preparation method according to any one of claims 1 to 3, characterized in that, The pH value of the mixture A is 3 to 6.9, preferably 4.4 to 6.

4.

5. The preparation method according to any one of claims 1 to 4, characterized in that, The curing temperature is 50~100℃, preferably 55~80℃, and the curing time is 10~300min, preferably 30~250min.

6. The preparation method according to any one of claims 1 to 5, characterized in that, In step (2), the injection time of the alkyl silicate hydrolysate is 500-6000 min, preferably 1000-4000 min, and the mass ratio of the total amount of ultrapure water and alkyl silicate hydrolysate is 1:(0.5-15), preferably 1:(2-10).

7. The preparation method according to any one of claims 1 to 6, characterized in that, The alkaline catalyst is selected from at least one of tetramethylammonium hydroxide, triethanolamine, ammonia, dipropylamine, and triethylamine.

8. The preparation method according to any one of claims 1 to 7, characterized in that, The pH value of the reaction solution in step (2) is 7.5~10.5, preferably 8~10.

9. The colloidal silica with controllable association degree prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The degree of association of the colloidal silica with controllable association is 1.5 to 3.

0.

10. The application of the colloidal silica with controllable association as described in claim 9 in the field of chemical mechanical polishing.

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