Iron oxide coated silica core-shell nanoparticles, and methods of making and using the same

Abstract

The application discloses iron oxide coated silica core-shell nanoparticles and a preparation method and application thereof. The iron oxide coated silica core-shell nanoparticles comprise silica nanoparticles as an inner core and iron oxide nanoparticles as an outer shell coated on the inner core surface of the silica nanoparticles; the particle size is 22-112 nm; and the particle uniformity is 0.08-0.3. The preparation method of the iron coated silica nanoparticles provided by the application adopts the measure of adjusting the pH of slurry for multiple times, avoids the agglomeration of nanoparticles in a solution near the isoelectric point, and is thus favorable for finally obtaining core-shell nanoparticles with uniform monodispersity. No surfactant is used in the preparation process, and there is no complicated post-treatment process, thereby reducing the production cost. The uniformly monodispersed nanoparticles prepared by the method have great potential in the field of chemical mechanical polishing.

Description

TECHNICAL FIELD

[0001] The application relates to iron oxide coated silica core-shell nanoparticles and a preparation method and application thereof, and belongs to the polishing material field. BACKGROUND

[0002] In the field of metal chemical mechanical polishing, abrasive particles are an important component in polishing liquid. In order to achieve high global flatness, the size of the abrasive particles is below 100 nm, and good monodispersity is required. At the same time, chemical action is generated through oxidation reaction, and hydrogen peroxide is usually used as an oxidizing agent, and Fe 3+ is used as a catalyst. Because Fe 3+ metal ions are easy to remain on the wafer surface after the polishing process, surface defects are formed in the subsequent process, and the global flatness is affected. Compared with the traditional Fe 3+ catalyst, in the iron coated silica core-shell nanoparticles, iron is fixed on the nanosilica particles in the form of a solid, and the prepared nanocore-shell particles can simultaneously play the roles of chemical catalysis and mechanical grinding in chemical mechanical polishing.

[0003] The preparation method of metal-coated silica core-shell nanoparticles is relatively mature. However, it is still difficult to produce monodisperse nanoparticles with a particle size of less than 100 nm in aqueous solution without surfactants. A preparation method of SiO2 / IO core-shell particles is reported in Langmuir 2014, 30, 9850-9858. Nanosilica particles are dispersed in 2-ethoxyethyl ether, and tridecahydridotriiron is added in an oil bath at 70℃, and heated at 160℃ for two hours, cooled to 70℃, and the process is repeated three times, and finally the particles are collected by centrifugal alcohol washing. The nanoparticles prepared by this method are in the range of 600-700 nm. The preparation method of SiO2@Fe3O4 core-shell nanoparticles is reported in ACS Omega 2019, 4, 528-534. First, nanosilica particles are dispersed in ethanol, and triethylene glycol is added as a dispersant, and iron acetate is added as an iron source to the solution. The mixed solution is reacted at 210℃ for one hour, and after cooling to room temperature, it is centrifuged and alcohol-washed to collect. The nanoparticles prepared by this method are in the range of 200-300 nm. Domestic patent CN103411816A provides a preparation method of Fe3O4-coated silica core-shell nanospheres. First, nanosilica particles are dispersed in a mixed solution of ethylene glycol and water, and after uniform dispersion, ferrous chloride is added, and stirred in a water bath at 45℃ for 5 hours, and then the particles are collected by centrifugal alcohol washing. Domestic patent CN1506407A provides a preparation method of nanosilica / Fe3O4 composite particle material. First, nanosilica particles are dispersed in water, and a mixed solution of divalent iron salt and trivalent iron salt is added in a certain proportion, and the pH of the solution is adjusted to 8-10 by adding alkali, and aged at 90℃, and finally the composite material is separated and dried.

[0004] Currently, the preparation method of iron oxide-coated silica core-shell nanoparticles is mainly realized by two methods. One is to first synthesize iron oxide compound nanoparticles, and then graft them to the surface of silica through a branch group. In this method, more surfactants are usually used, the cost is high, and the subsequent product separation and collection are difficult. The other method is to grow iron ions on the surface of silica through a precipitation method. This method easily causes nanosilica to agglomerate due to the addition of alkali, and it is difficult to maintain a monodisperse state. Therefore, the uniformly monodisperse iron oxide-coated silica nanocore-shell particles provided by the present application can effectively avoid the above problems, and have a wide application prospect in the fields of high-tech such as health and semiconductors. SUMMARY

[0005] In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the present application provides a preparation method of uniformly monodisperse iron oxide-coated silica core-shell nanoparticles. The method can obtain uniformly monodisperse iron-coated silica core-shell nanoparticles in aqueous solution.

[0006] According to one aspect of the present application, there is provided a ferric oxide coated silica core-shell nanoparticle, comprising a silica nanoparticle as an inner core and a ferric oxide nanoparticle as an outer shell coated on the surface of the silica nanoparticle inner core;

[0007] The particle size of the ferric oxide coated silica core-shell nanoparticle is 22-112 nm;

[0008] The particle size of the ferric oxide coated silica core-shell nanoparticle is 22-112 nm;

[0009] The ferric oxide nanoparticle is selected from at least one of ferrous oxide, ferric oxide, and ferroferric oxide;

[0010] The silica nanoparticle is spherical and has a diameter of 20-100 nm;

[0011] The particle size of the ferric oxide nanoparticle is 1-2 nm;

[0012] The mass of the ferric element in the ferric oxide coated silica core-shell nanoparticle is 0.1-1 wt% of the mass of the silica.

[0013] The ferric oxide coated silica core-shell nanoparticle is uniformly and singly dispersed in an aqueous solution and does not aggregate and settle.

[0014] According to another aspect of the present application, there is provided a method for preparing the above-mentioned ferric oxide coated silica core-shell nanoparticle, comprising the following steps:

[0015] Mixing an aqueous solution containing silica nanoparticles, a basic catalyst, and a silane coupling agent with an aqueous solution containing a ferric salt, and reacting to obtain the ferric oxide coated silica core-shell nanoparticle.

[0016] The basic catalyst is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia, triethylamine, and pyridine;

[0017] The silane coupling agent is selected from at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-cyanoethyltrimethoxysilane, 2-cyanoethyltriethoxysilane, and N-aminoethyl γ-aminopropyltrimethoxysilane;

[0018] In the aqueous solution containing silica nanoparticles, a basic catalyst, and a silane coupling agent,

[0019] The mass content of the silica nanoparticles is 1-10 wt%;

[0020] The mass content of the basic catalyst is 1-10 wt%;

[0021] The mass content of the silane coupling agent is 0.01-1 wt%.

[0022] The iron salt is selected from at least one of ferric nitrate, ferric chloride, and ferric sulfate;

[0023] The mass content of the iron salt in the aqueous solution containing the iron salt is 1-5 wt%;

[0024] The mass ratio of the silica nanoparticles to the iron salt is 1:0.001-0.3.

[0025] The temperature of the reaction is 60-90°C;

[0026] The time of the reaction is 6-10 h.

[0027] Specifically,

[0028] (1) dispersing silica nanoparticles in water, the silica content being 1-10%, and adding a basic catalyst;

[0029] (2) adding a silane coupling agent dropwise to the slurry obtained in step (1) within a certain time; the silane coupling agent feeding time ranges from 1 to 400 minutes.

[0030] (3) aging for 3-6 hours at 60-90°C;

[0031] (4) adding the slurry obtained in step (3) dropwise to an acidic pH adjuster and maintaining the slurry as acidic; the pH adjuster is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, oxalic acid, and citric acid.

[0032] Optionally, the mass concentration of the pH adjuster is 1%-10%.

[0033] Optionally, the pH adjustment range is 2-4.

[0034] (5) dissolving a ferric ion salt in deionized water;

[0035] (6) adding the solution obtained in step (5) dropwise to the solution obtained in step (4) within a certain time, and adding a pH adjuster to maintain the pH stable; the pH adjuster is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, aqueous ammonia, triethylamine, and pyridine.

[0036] The feeding time is 0.5-10 hours.

[0037] (7) aging for 6-12 hours at 60-90°C to obtain uniform monodisperse iron-coated silica core-shell nanoparticles.

[0038] According to another aspect of the present application, there is provided the use of the iron oxide coated silica core-shell nanoparticles as described above in chemical mechanical polishing.

[0039] The beneficial effects that can be achieved by the present application include:

[0040] The preparation method of the iron oxide coated silica nanoparticles provided by the present application adopts the measure of adjusting the pH of the slurry multiple times, thereby avoiding the agglomeration of the nanoparticles in the solution near the isoelectric point, and thus being conducive to obtaining the final uniform and monodisperse core-shell nanoparticles. No surfactant is used in the preparation process, and there is no complicated post-treatment process, thereby reducing the production cost. Moreover, the uniform and monodisperse nanoparticles prepared by the method have great potential in the field of chemical mechanical polishing. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a particle size distribution graph of the product prepared in Example 1.

[0042] Figure 2 is a TEM graph of the product prepared in Example 1, with a scale of 20 nm.

[0043] Figure 3 is a particle size distribution graph of the product prepared in Comparative Example 2.

[0044] Figure 4 is a particle size distribution graph of the product prepared in Example 3.

[0045] Figure 5 is a particle size distribution graph of the product prepared in Example 4. DETAILED DESCRIPTION

[0046] The specific embodiments of the present application will be further described in detail below in conjunction with the accompanying drawings and examples, but these examples do not constitute a limitation on the present application. Those skilled in the art can modify the details and forms of the technical solutions of the present application within the principle of the present application, and such modifications all fall within the protection scope of the present application.

[0047] The particle size data in the embodiments of the present application are detected by using a Malvern laser particle size analyzer.

[0048] Example 1

[0049] Into a 2L beaker, 80g of 45nm diameter nanosilica particles and 1600mL of deionized water were added, 10g of 5wt.% ammonia water was added, and the slurry A was obtained by stirring. Subsequently, 8g of 3-aminopropyltrimethoxysilane was added dropwise into the slurry A by using a syringe pump, and the slurry B was obtained by heating at 70°C for 5h and then cooling down. The slurry B was added dropwise into 5wt.% nitric acid, and the slurry C was obtained by keeping the pH at 3. 6g of iron nitrate nonahydrate was dissolved into 300mL of deionized water to prepare solution D. The solution D was added dropwise into the slurry C by using a syringe pump, and 4wt.% sodium hydroxide solution was added dropwise to keep the solution pH at 3 during the addition. After the addition was completed for 3h, the mixed slurry was heated to 90°C and aged for 12h.

[0050] The obtained sample was recorded as 1#, and the particle size was analyzed by using a Malvern laser particle size analyzer. The average particle size was 47nm, and the concentration PDI value was 0.07. The results are shown in Figure 1 , and the TEM results are shown in Figure 2 .

[0051] The particle size analysis results are as follows:

[0052]

[0053] Example 2

[0054] Into a 2L beaker, 50g of 67nm diameter nanosilica particles and 1000mL of deionized water were added, 14g of 2wt.% triethylamine solution was added, and the slurry A was obtained by stirring. Subsequently, 10g of 3-mercaptopropyltriethoxysilane was added dropwise into the slurry A by using a syringe pump, and the slurry B was obtained by heating at 60°C for 5h and then cooling down. The slurry B was added dropwise into 3wt.% hydrochloric acid, and the slurry C was obtained by keeping the pH at 3.5. 7g of iron chloride hexahydrate was dissolved into 360mL of deionized water to prepare solution D. The solution D was added dropwise into the slurry C by using a syringe pump, and 2wt.% ammonia water was added dropwise to keep the solution pH at 3.5 during the addition. After the addition was completed for 3.5h, the mixed slurry was heated to 70°C and aged for 10h.

[0055] The obtained sample was recorded as 2#, and the particle size was analyzed by using a Malvern laser particle size analyzer. The average particle size was 69.7nm, and the concentration PDI value was 0.17. The results are shown in Figure 3 .

[0056] The particle size analysis results are as follows:

[0057]

[0058] Example 3

[0059] Into a 5L beaker, 150g of 90nm diameter nanosilica particles and 3500mL of deionized water were added, 26g of 2wt.% triethylamine solution was added, and the slurry A was obtained by stirring. Subsequently, 21g of 3-mercaptopropyltriethoxysilane was added dropwise into the slurry A using a syringe pump, and the slurry B was obtained by heating at 60°C for 5 hours and then cooling down. The slurry B was added dropwise into 5wt.% nitric acid, and the slurry C was obtained by maintaining the pH at 2.5. 13g of iron nitrate nonahydrate was dissolved in 330mL of deionized water to prepare solution D. The solution D was added dropwise into the slurry C using a syringe pump, and 4wt.% sodium hydroxide solution was added dropwise to maintain the solution pH at 2.5 during the addition. After the addition was completed in 2.6h, the mixed slurry was heated to 80°C and aged for 10h.

[0060] The obtained sample was recorded as 3#, and the particle size was analyzed by a Malvern laser particle size analyzer. The average particle size was 92.71nm, and the concentration PDI value was 0.16. The results are shown in Figure 4 .

[0061] The particle size analysis results are as follows:

[0062]

[0063] Example 4

[0064] Into a 1L beaker, 30g of 52nm diameter nanosilica particles and 750mL of deionized water were added, 5g of 2wt.% ammonia water was added, and the slurry A was obtained by stirring. Subsequently, 3g of N-aminoethyl γ-aminopropyltrimethoxysilane was added dropwise into the slurry A using a syringe pump, and the slurry B was obtained by heating at 60°C for 4 hours and then cooling down. The slurry B was added dropwise into 5wt.% oxalic acid, and the slurry C was obtained by maintaining the pH at 2. 5g of iron sulfate was dissolved in 210mL of deionized water to prepare solution D. The solution D was added dropwise into the slurry C using a syringe pump, and 3wt.% sodium hydroxide solution was added dropwise to maintain the solution pH at 2 during the addition. After the addition was completed in 2h, the mixed slurry was heated to 80°C and aged for 9h.

[0065] The obtained sample was recorded as 4#, and the particle size was analyzed by a Malvern laser particle size analyzer. The average particle size was 54nm, and the concentration PDI value was 0.22. The results are shown in Figure 5 .

[0066] The particle size analysis results are as follows:

[0067]

[0068] The above merely describes several embodiments of the present application, and does not limit the present application in any form. Although the present application is disclosed with the preferred embodiments, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the disclosed technical contents without departing from the scope of the technical solutions of the present application, and the equivalent embodiments are equivalent to the equivalent embodiments, which are within the scope of the technical solutions.

Claims

1. A method for preparing iron oxide-coated silica core-shell nanoparticles, characterized in that, Includes the following steps: (1) Disperse silica nanoparticles in water and add an alkaline catalyst; (2) Add the silane coupling agent dropwise to the slurry obtained in step (1) over a period of 1 to 400 minutes; (3) The slurry obtained in step (2) is aged at 60~90℃ for 3~6 hours; (4) Add the slurry obtained in step (3) dropwise into the acidic pH adjuster and maintain the pH of the slurry at 2~4; (5) Dissolve the ferric salt in deionized water to form an ferric salt solution; (6) Add the iron salt solution obtained in step (5) dropwise to the slurry obtained in step (4), and add a pH adjuster to maintain pH stability; the pH adjuster is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia, triethylamine, and pyridine, and the dropwise addition time is 0.5 to 10 hours. (7) The mixed slurry obtained in step (6) is aged at 60~90℃ for 6~12 hours to obtain uniform and monodisperse iron oxide coated silica core-shell nanoparticles; wherein the iron oxide coated silica core-shell nanoparticles prepared by the method include silica nanoparticles as the core and iron oxide nanoparticles as the shell covering the surface of the silica nanoparticle core; the particle size of the iron oxide coated silica core-shell nanoparticles is 22~112nm and the particle uniformity PDI is 0.08~0.

3.

2. The preparation method according to claim 1, characterized in that, The acidic pH adjuster is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, acetic acid, oxalic acid, and citric acid; The alkaline catalyst is selected from at least one of sodium hydroxide, potassium hydroxide, sodium carbonate, ammonia, triethylamine, and pyridine. The silane coupling agent is selected from at least one of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 2-cyanoethyltrimethoxysilane, 2-cyanoethyltriethoxysilane, and N-aminoethylγ-aminopropyltrimethoxysilane. In an aqueous solution containing silica nanoparticles, an alkaline catalyst, and a silane coupling agent, The mass content of the silica nanoparticles is 1~10 wt%; The alkaline catalyst has a mass content of 1~10 wt%; The mass content of the silane coupling agent is 0.01~1wt%.

3. The preparation method according to claim 1, characterized in that, The iron salt is selected from at least one of ferric nitrate, ferric chloride, and ferric sulfate; In the aqueous solution containing iron salt, the mass content of the iron salt is 1~5 wt%; The mass ratio of the silica nanoparticles to the iron salt is 1:0.001~0.3.

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