CN114560468B

CN114560468B - Silicon dioxide for chemical mechanical polishing and preparation method and application thereof

Info

Publication number: CN114560468B
Application number: CN202210175071.XA
Authority: CN
Inventors: 秦冬霞; 司徒粤; 黄丹; 程翔; 梁少彬
Original assignee: Guangzhou Feixue Material Technology Co ltd; Jinsanjiang Zhaoqing Silicon Material Co ltd; South China University of Technology SCUT
Current assignee: Guangzhou Feixue Material Technology Co ltd; Jinsanjiang Zhaoqing Silicon Material Co ltd; South China University of Technology SCUT
Priority date: 2022-02-25
Filing date: 2022-02-25
Publication date: 2022-09-16
Anticipated expiration: 2042-02-25
Also published as: CN114560468A

Abstract

The invention belongs to the technical field of nano materials, and particularly relates to silicon dioxide for chemical mechanical polishing as well as a preparation method and application thereof. The invention provides a preparation method of nano spherical silicon dioxide for chemical mechanical polishing, which takes Tetraethoxysilane (TEOS) as a silicon source, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) and self-made surfactant as a structure directing agent, ethanol and water as a cosolvent, and the components react according to a specific proportion, so that the gradient particle size of the silicon dioxide can be effectively regulated and controlled to 20-100 nm, the uniformity of the particle size is good, the dispersibility of the silicon dioxide is favorably improved, the rate of chemical mechanical polishing can be effectively improved when the nano spherical silicon dioxide is applied to chemical mechanical polishing liquid, the surface roughness of the polished material is reduced, and the nano spherical silicon dioxide is a good abrasive material used as the chemical mechanical polishing liquid of a semiconductor device.

Description

Silicon dioxide for chemical mechanical polishing and preparation method and application thereof

Technical Field

The invention belongs to the technical field of nano materials, and particularly relates to silicon dioxide for chemical mechanical polishing as well as a preparation method and application thereof.

Background

Chemical Mechanical Polishing (CMP) is a key technology for achieving global planarization of semiconductor devices (including silicon substrates, oxide dielectric layers, and interconnect materials), and is critical to the fabrication of high-precision, high-performance, high-integration chips. The basic principle of the CMP process is to rotate a workpiece to be polished relative to a polishing pad under a certain down pressure and in the presence of a polishing liquid (a mixed liquid consisting of ultrafine particles, a chemical oxidizer and a liquid medium), to complete the removal of material from the surface of the workpiece by means of the mechanical grinding of abrasive particles and the corrosive action of the chemical oxidizer, and to obtain a smooth surface. The polishing solution is one of the key elements of CMP, so the performance of the polishing solution directly affects the production quality and scale of chips. The abrasive is the main component of the CMP polishing solution and plays a role in mechanical micro-grinding and material conveying in CMP. Silicon dioxide is used as an abrasive of a commonly used CMP polishing solution, and the size, hardness and morphology of the particle size have great influence on the performance of a polished workpiece.

Currently, abrasives used in CMP polishing solutions are mainly silica sol and fumed silica. The silica sol with large grain diameter and high purity is difficult to produce and the preparation process is complex; the silicon dioxide prepared by the gas phase method has complex preparation process, high equipment requirement and large energy consumption.

Chinese patent application CN113652200A discloses a self-assembled nano silica abrasive, polishing solution containing the abrasive and applications, including synthesis of silica seed solution and growth of silica seeds: mixing a PEO-PPO-PEO triblock copolymer, a solution containing spherical silica and a solution containing a catalyst; adding a solution containing a silicon precursor at the temperature of between 40 and 60 ℃ to obtain a solution A; stirring and reacting for 20-30 hours to obtain silicon dioxide seed liquid, heating to boil, dripping silicic acid solution, and reacting for 1-3 hours. The nano silicon dioxide microspheres obtained by the method have the advantages of non-uniform particle size, high reaction temperature and large energy consumption in the process.

Chinese patent application CN113773806A discloses a nano silicon dioxide abrasive and a preparation method and application thereof, wherein, the spherical nano silicon dioxide abrasive synthesized by taking sodium silicate as a silicon source is adjusted in pH value by a first alkaline substance, mixed with an electrolyte solution and heated to obtain a mother solution; and continuously adding an active silicic acid solution into the mother liquor, adjusting the pH value of the mixed solution of the active silicic acid solution and the mother liquor by using a second alkaline substance added in sections, and keeping heating to generate the nano silicon dioxide abrasive. The preparation method adopts segmented base catalysis to improve the hardness of the silica sol particles, but needs to remove particle impurities and ion impurities generated in the preparation process, and takes longer time; meanwhile, although the invention carries out the synthesis of the silicon dioxide by a constant liquid level polymerization growth method, the preparation process of adding different alkalis in sections is complex and is not beneficial to wide popularization.

Therefore, there is a need to provide a method for preparing nano spherical silica for chemical mechanical polishing, which can prepare nano spherical particles with easily controllable particle size, uniform particle distribution, and low agglomeration tendency in a simple preparation process, and can effectively increase the polishing rate to meet the requirement of good application in chemical mechanical polishing solutions.

Disclosure of Invention

The nano spherical silicon dioxide prepared by the method has the advantages of particle size of 20-100 nm, easy regulation and control of particle size, uniform particle distribution, difficult agglomeration and good dispersibility, can be applied to chemical mechanical polishing solution, can effectively improve the chemical mechanical polishing rate, and reduce the surface roughness of the polished material and the mechanical damage caused by the silicon dioxide, and has simple preparation process and low cost.

The technical scheme of the invention is as follows:

a preparation method of silicon dioxide for chemical mechanical polishing comprises the following steps:

s1, dissolving a surfactant and a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) in a mixed solvent of water and ethanol, and stirring until the mixture is fully dissolved to obtain a mixed solution;

s2, adjusting the pH value of the mixed solution obtained in the step S1 to 8-10, stirring for the first time, adding Tetraethoxysilane (TEOS), continuing stirring for the second time, and then centrifuging, washing, drying and firing to obtain the silicon dioxide for chemical mechanical polishing.

Further, the preparation method of the surfactant comprises the following steps:

step 1: dissolving 5-20 parts by weight of 2, 2-dimethylolpropionic acid (DMPA) in 30-70 parts by weight of anhydrous N, N-Dimethylformamide (DMF) to obtain a mixed solution 1;

step 2: dissolving 0.01-0.1 part by weight of bis (dimethylaminoethyl ether) in 30-45 parts by weight of isophorone diisocyanate (IPDI) to obtain a mixed solution 2;

and step 3: under the condition of stirring, dripping the mixed solution 1 obtained in the step 1 into the mixed solution 2 obtained in the step 2, and reacting after finishing dripping to obtain a prepolymer;

and 4, step 4: dissolving 0.1-0.5 part by weight of bis-dimethylaminoethyl ether in 50-90 parts by weight of PEG 600 to obtain a mixed solution 3;

and 5: and (3) under the condition of stirring, dripping the prepolymer obtained in the step (3) into the mixed solution (3) obtained in the step (4), reacting after finishing dripping, and finally vacuumizing to remove the solvent N, N-dimethylformamide to obtain the surfactant.

Further, in the step 3, under the stirring condition that the stirring speed is 500-1000 rpm, the mixed solution 1 obtained in the step 1 is dripped into the mixed solution 2 obtained in the step 2 and heated to 50-80 ℃, and after the dripping is finished, the reaction is carried out for 40-90 min, and the temperature in the reaction process is 50-80 ℃;

in the step 5, under the stirring condition that the stirring speed is 500-1000 rpm, the prepolymer obtained in the step 3 is dripped into the mixed liquid 3 obtained in the step 4 and heated to 50-80 ℃, and after the dripping is finished, the reaction is carried out for 1-3 h, wherein the temperature in the reaction process is 50-80 ℃.

Further, in the preparation method of the silicon dioxide for chemical mechanical polishing, the weight ratio of the surfactant, the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, the ethanol, the water and the tetraethoxysilane is 1-5: 5-15: 20-45: 1-10.

Further, in the step S2, the pH of the mixed solution obtained in the step S1 is adjusted to 8 to 10 with 1% tetramethylammonium hydroxide.

Further, the stirring speed in the step S1 is 500-1000 rpm; in the step S2, the primary stirring time is 3-7 h, and the stirring speed is 500-1000 rpm; the secondary stirring time is 12-24 h, and the stirring speed is 500-1000 rpm.

Further, the burning temperature in the step S2 is 300-700 ℃, and the burning time is 1-3 h.

The silicon dioxide prepared by the preparation process is solid spherical and has the particle size of 20-100 nm.

In addition, the silicon dioxide prepared by the preparation method is applied to preparing chemical mechanical polishing liquid abrasive, in particular to the abrasive of the chemical polishing liquid suitable for semiconductor materials and devices.

According to the prior art, the silicon dioxide abrasive mainly plays a role in mechanical micro-grinding and material transmission in chemical mechanical polishing, the property of the silicon dioxide has important influence on the polishing solution, and the polishing solution prepared by adopting the spherical silicon dioxide with uniform particle size has less scratch and nick on a semiconductor polishing substrate; meanwhile, the polishing is divided into rough polishing, middle polishing and fine polishing, and the particle sizes corresponding to different requirements are different, so that how to adopt a simpler method to perform gradient regulation and control on the particle size of the silicon dioxide in the same technical scheme is a very key technical difficulty to be overcome.

By adopting the preparation method provided by the invention, the silicon dioxide with the particle size of 20-100 nm can be prepared through one-step reaction, and the preparation method is simple and easy to control. Firstly, the surfactant provided by the invention is used together with P123 according to a certain proportion as a structure directing agent for synthesizing nano silicon dioxide microspheres, a silicon source (ethyl orthosilicate) is guided to be hydrolyzed into a spherical structure, and the obtained silicon dioxide is not easy to agglomerate, so that the silicon dioxide can be better dispersed in a solution. Further, the surfactant and the P123 provided by the invention are dissolved in mixed solvents of ethanol and a proper amount of water in different proportions, and the concentration of the system is adjusted by changing the amounts of the surfactant, the P123, the ethanol, the water and the silicon source, so that the particle size of the silicon dioxide can be effectively adjusted, and the nano spherical silicon dioxide with different particle sizes can be obtained; and finally, adjusting the pH value of the reaction solution to 8.0-10, providing an alkaline environment to be more favorable for hydrolyzing tetraethoxysilane and then performing polycondensation to form nano particles, and then, burning at high temperature to remove the surfactant and the block polymer P123, thereby obtaining the solid spherical silicon dioxide with the particle size of 20-100 nm.

Compared with the prior art, the nano spherical silicon dioxide for chemical mechanical polishing and the preparation method thereof provided by the invention have the following advantages:

(1) according to the preparation method of the nano spherical silicon dioxide for chemical mechanical polishing, provided by the invention, Tetraethoxysilane (TEOS) is used as a silicon source, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) and a self-made surfactant are used as structure directing agents, ethanol and water are used as cosolvents, and the components react according to a specific proportion, so that the gradient particle size of the silicon dioxide can be effectively regulated to 20-100 nm, the particle size uniformity is good, the agglomeration is not easy to occur, and the dispersibility of the silicon dioxide is favorably improved.

(2) The invention is applied to the chemical mechanical polishing solution, can effectively improve the mechanical polishing speed and reduce the microroughness of the polished surface, and is particularly suitable for the abrasive of the chemical polishing solution of semiconductor materials and devices.

(3) The preparation process of the silicon dioxide provided by the invention is simple and easy to operate, the silicon dioxide with the particle size of 20-100 nm can be prepared through one-step reaction, the technical problem that the silicon dioxide with different gradient particle sizes can be prepared through a multi-step method in the prior art is solved, the whole reaction process can be completely carried out at normal temperature and normal pressure, the reaction condition is mild, and the large-scale production is favorably realized.

Drawings

FIG. 1 is an SEM image of silica having a particle size of 20-30nm prepared in example 1;

FIG. 2 is an SEM photograph of silica having a particle size of 40-50nm prepared in example 2;

FIG. 3 is an SEM photograph of silica having a particle size of 60-80nm prepared in example 3;

FIG. 4 is an SEM photograph of silica having a particle size of 80-100nm prepared in example 4;

FIG. 5 is an SEM photograph of the silica prepared in comparative example 1;

FIG. 6 is an SEM photograph of the silica prepared in comparative example 2.

Detailed Description

The present invention is further illustrated by the following description of specific embodiments, which are not intended to limit the invention, and various modifications and improvements can be made by those skilled in the art based on the basic idea of the invention, but the invention is within the protection scope of the invention.

Wherein, the reagents used in the invention can be purchased from conventional reagent production and sale companies.

Example 1A method for preparing silicon dioxide for chemical mechanical polishing

The preparation method of the silicon dioxide for chemical mechanical polishing comprises the following steps:

(1) preparing a surfactant:

step 1: dissolving 10.0g of 2, 2-dimethylolpropionic acid in 30.0g of anhydrous N, N-dimethylformamide to obtain a mixed solution 1;

step 2: dissolving 0.02g of bis-dimethylaminoethyl ether in 30.5g of isophorone diisocyanate to obtain a mixed solution 2;

and step 3: under the condition of stirring, dripping the mixed solution 1 obtained in the step 1 into the mixed solution 2 obtained in the step 2, heating the mixed solution 2 to 80 ℃, reacting for 45min after finishing dripping, and keeping the temperature in the reaction process at 80 ℃ to obtain a prepolymer;

and 4, step 4: dissolving 0.2g of bis-dimethylaminoethyl ether in 60.0g of PEG 600 to obtain a mixed solution 3;

and 5: and (3) dripping the prepolymer obtained in the step (3) into the mixed solution (3) obtained in the step (4) under the condition of stirring, heating the mixed solution (3) to 80 ℃, reacting for 1h after finishing dripping, keeping the temperature in the reaction process at 80 ℃, and finally vacuumizing to remove the solvent N, N-dimethylformamide to obtain the surfactant.

(2) Preparing nano spherical silicon dioxide:

s1: dissolving 1.2g of the surfactant and 1.0g of the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) in a mixed solvent of 5.0g of ethanol and 44.8g of water, and stirring the mixture on a magnetic stirrer until the mixture is fully dissolved at the stirring speed of 500rpm to obtain a mixed solution;

s2: and (3) adjusting the pH value of the mixed solution obtained in the step S1 to 8.0 by using 1% tetramethylammonium hydroxide, stirring for 3h at the stirring speed of 500rpm, adding 1.6g of tetraethoxysilane, stirring for 12h at room temperature at the stirring speed of 500rpm, centrifuging, washing and drying the obtained white solution, and burning for 3h at 300 ℃ to obtain nano silicon dioxide microsphere powder.

Example 2A method for preparing silicon dioxide for chemical mechanical polishing

(1) preparing a surfactant:

step 1: dissolving 13.8g of 2, 2-dimethylolpropionic acid in 42.5g of anhydrous N, N-dimethylformamide to obtain a mixed solution 1;

step 2: dissolving 0.05g of bis-dimethylaminoethyl ether in 38.6g of isophorone diisocyanate to obtain a mixed solution 2;

and step 3: under the condition of stirring, dropwise adding the mixed solution 1 obtained in the step 1 into the mixed solution 2 obtained in the step 2, heating the mixed solution 2 to 72 ℃, reacting for 60min after dropwise adding is completed, and keeping the temperature in the reaction process at 72 ℃ to obtain a prepolymer;

and 4, step 4: dissolving 0.3g of bis-dimethylaminoethyl ether in 75.5g of PEG 600 to obtain a mixed solution 3;

and 5: and (3) dripping the prepolymer obtained in the step (3) into the mixed solution (3) obtained in the step (4) under the condition of stirring, heating the mixed solution (3) to 70 ℃, reacting for 1.5 hours after finishing dripping, keeping the temperature at 70 ℃ in the reaction process, and finally vacuumizing to remove the solvent N, N-dimethylformamide to obtain the surfactant.

(2) Preparing nano spherical silicon dioxide:

s1: dissolving the 2.3g of surfactant and 3.1g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) in a mixed solvent of 8.6g of ethanol and 36.2g of water, and stirring on a magnetic stirrer until the mixture is fully dissolved at the stirring speed of 700rpm to obtain a mixed solution;

s2: and (3) adjusting the pH value of the mixed solution obtained in the step S1 to 8.5 by using 1% tetramethylammonium hydroxide, stirring for 4h at the stirring speed of 700rpm, adding 2.4g of tetraethoxysilane, stirring for 18h at room temperature at the stirring speed of 700rpm, centrifuging, washing and drying the obtained white solution, and burning for 2h at 400 ℃ to obtain nano silicon dioxide microsphere powder.

Example 3 preparation of silica for chemical mechanical polishing

(1) preparing a surfactant:

step 1: dissolving 18.7g of 2, 2-dimethylolpropionic acid in 52.3g of anhydrous N, N-dimethylformamide to obtain a mixed solution 1;

and 2, step: dissolving 0.08g of bis-dimethylamine ethyl ether in 44.5g of isophorone diisocyanate to obtain a mixed solution 2;

and step 3: under the condition of stirring, dripping the mixed solution 1 obtained in the step 1 into the mixed solution 2 obtained in the step 2, heating the mixed solution 2 to 68 ℃, reacting for 75min after finishing dripping, and keeping the temperature in the reaction process at 68 ℃ to obtain a prepolymer;

and 4, step 4: dissolving 0.4g of bis-dimethylaminoethyl ether in 80.2g of PEG 600 to obtain a mixed solution 3;

and 5: and (3) dripping the prepolymer obtained in the step (3) into the mixed solution (3) obtained in the step (4) under the condition of stirring, heating the mixed solution (3) to 65 ℃, reacting for 2 hours after finishing dripping, keeping the temperature in the reaction process at 65 ℃, and finally vacuumizing to remove the solvent N, N-dimethylformamide to obtain the surfactant.

(2) Preparing nano spherical silicon dioxide:

s1: dissolving the 3.4g of surfactant and 4.1g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) in a mixed solvent of 10.4g of ethanol and 28.7g of water, and stirring on a magnetic stirrer at a stirring speed of 850rpm to obtain a mixed solution;

s2: and (3) adjusting the pH value of the mixed solution obtained in the step S1 to 9.0 by using 1% tetramethylammonium hydroxide, stirring for 5.5h at the stirring speed of 850rpm, adding 6.0g of tetraethoxysilane, stirring for 20h at room temperature at the stirring speed of 850rpm, centrifuging, washing and drying the obtained white solution, and burning for 1.5h at 550 ℃ to obtain nano silicon dioxide microsphere powder.

Example 4 preparation of silica for chemical mechanical polishing

(1) preparing a surfactant:

step 1: dissolving 20g of 2, 2-dimethylolpropionic acid in 68.5g of anhydrous N, N-dimethylformamide to obtain a mixed solution 1;

step 2: dissolving 0.1g of bis-dimethylamine ethyl ether in 45.0g of isophorone diisocyanate to obtain a mixed solution 2;

and step 3: under the condition of stirring, dripping the mixed solution 1 obtained in the step 1 into the mixed solution 2 obtained in the step 2, heating the mixed solution 2 to 80 ℃, reacting for 90min after finishing dripping, and keeping the temperature in the reaction process at 80 ℃ to obtain a prepolymer;

and 4, step 4: dissolving 0.5g of bis-dimethylaminoethyl ether in 90g of PEG 600 to obtain a mixed solution 3;

and 5: and (3) dripping the prepolymer obtained in the step (3) into the mixed solution (3) obtained in the step (4) under the condition of stirring, heating the mixed solution (3) to 50 ℃, reacting for 3 hours after finishing dripping, keeping the temperature at 50 ℃ in the reaction process, and finally vacuumizing to remove the solvent N, N-dimethylformamide to obtain the surfactant.

(2) Preparing nano spherical silicon dioxide:

s1: dissolving the 4.7g of surfactant and 2.6g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) in a mixed solvent of 14.3g of ethanol and 22.3g of water, and stirring on a magnetic stirrer at the stirring speed of 1000rpm to obtain a mixed solution;

s2: and (3) adjusting the pH value of the mixed solution obtained in the step S1 to 10.0 by using 1% tetramethylammonium hydroxide, stirring for 6h at the stirring speed of 1000rpm, adding 8.5g of tetraethoxysilane, stirring for 24h at room temperature at the stirring speed of 1000rpm, centrifuging, washing and drying the obtained white solution, and burning for 1h at 700 ℃ to obtain nano silicon dioxide microsphere powder.

Comparative example 1 a method for preparing silica for chemical mechanical polishing

Compared with example 4, comparative example 1 is different in that P123 is used instead of the surfactant prepared according to the present invention, and other components and preparation steps are the same as those of example 4.

Comparative example 2 a method for preparing silica for chemical mechanical polishing

Comparative example 2 is different from example 4 in that P123 is replaced with the surfactant prepared according to the present invention, and other components are the same as those of example 4.

Test example I, particle size and morphology of silica

1. The test method comprises the following steps: the nano spherical silica prepared in the examples 1 to 4 and the comparative examples 1 to 2 of the present invention was observed under a scanning electron microscope.

2. And (3) test results: the electron microscope images of the nano spherical silica prepared in the examples 1 to 4 and the comparative examples 1 to 2 are shown in fig. 1 to 6, and as can be seen from fig. 1 to 4, the silica particles prepared in the examples 1 to 4 of the present invention have regular spherical shape, smooth surface, uniform particle size and uniform dispersion. As can be seen from fig. 5, the nano-spherical silica prepared in comparative example 1 has a serious particle agglomeration phenomenon, in which a plurality of spheres are associated together, and the particle size is much larger than that of the particles prepared in example 4; as can be seen from fig. 6, the nano silica particles prepared in comparative example 2 were strongly agglomerated, and a plurality of spheres were associated together.

Test example two, chemical mechanical polishing effect of silicon dioxide

1. Test materials: examples 1 to 4 and comparative examples 1 to 2.

2. The test method comprises the following steps: (1) preparing a polishing solution: respectively taking 25 parts of nano spherical silicon dioxide prepared in examples 1-4 and comparative examples 1-2, 3 parts of pH regulator tetramethylammonium hydroxide, 0.05 part of surfactant Berol610 and oxidant H ₂ O ₂ Is 5 parts by weight, is66.95 parts of ionized water, and then the ionized water is diluted by 5 times with the deionized water for testing.

(2) Performing a chemical mechanical polishing test: polishing tests were performed using a 4 inch diameter single crystal silicon, model UNIPOL1203 grinding polisher with the following process parameters: the flow rate of the polishing solution is 8mL/min, the polishing pressure is 35kPa, the rotation speed is 75rpm, the polishing time is 100min, and the polishing temperature is 30-35 ℃; the polishing pad is a polyurethane polishing pad matched with the polishing machine.

(3) The detection method of polishing rate and surface roughness comprises the following steps: the polishing rate is measured by a film thickness meter, the model is SKCH-1(A) of Shenyang Kejing automatic equipment Limited, and the average thickness difference of 9 points before and after polishing of each silicon wafer is measured and is calculated by dividing the polishing time; the surface roughness was averaged by measuring a plurality of times with a surface roughness meter (manufacturer: NewView5022 ZYGO).

3. And (3) test results:

the results of the tests on the polishing rate and surface roughness of the silica prepared by the present invention applied to the polishing slurry are shown in table 1.

TABLE 1

Group of	Polishing Rate (. mu.m/h)	Surface roughness Ra (nm)
			Example 1	1.01	0.08
Example 2	1.06	0.09
			Example 3	1.11	0.13
Example 4	1.16	0.15
			Comparative example 1	0.91	0.34
Comparative example 2	0.99	0.23

As can be seen from Table 1: after the nano spherical silicon dioxide prepared in the groups 1 to 4 of the embodiments of the invention is applied to the chemical mechanical polishing solution, the polishing rate is effectively improved and is more than 1um/h, the polished surface of the semiconductor crystal is smooth, and the surface roughness of the semiconductor crystal is effectively reduced and is less than 0.15 nm. The particles prepared in comparative examples 1 and 2 had slightly inferior polishing rates to those of examples 1 to 4, and had large surface roughness.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Those skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A preparation method of silicon dioxide for chemical mechanical polishing is characterized by comprising the following steps:

s1, dissolving the surfactant and the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer in a mixed solvent of water and ethanol, and stirring until the mixture is fully dissolved to obtain a mixed solution;

s2, adjusting the pH value of the mixed solution obtained in the step S1 to 8-10, stirring for the first time, adding tetraethoxysilane, continuing stirring for the second time, and then centrifuging, washing, drying and firing to obtain silicon dioxide for chemical mechanical polishing;

the preparation method of the surfactant comprises the following steps:

step 1: dissolving 5-20 parts by weight of 2, 2-dimethylolpropionic acid in 30-70 parts by weight of anhydrous N, N-dimethylformamide to obtain a mixed solution 1;

step 2: dissolving 0.01-0.1 part by weight of bis-dimethylaminoethyl ether in 30-45 parts by weight of isophorone diisocyanate to obtain a mixed solution 2;

and 5: and (4) under the condition of stirring, dripping the prepolymer obtained in the step (3) into the mixed solution (3) obtained in the step (4), reacting after finishing dripping, and finally vacuumizing to remove the solvent N, N-dimethylformamide to obtain the surfactant.

2. The method of preparing silica for chemical mechanical polishing according to claim 1, wherein the surfactant is prepared by: in the step 3, under the stirring condition that the stirring speed is 500-1000 rpm, the mixed liquid 1 obtained in the step 1 is dripped into the mixed liquid 2 obtained in the step 2 and heated to 50-80 ℃, and after the dripping is finished, the reaction is carried out for 40-90 min, and the temperature in the reaction process is 50-80 ℃;

3. The method of preparing silica for chemical mechanical polishing according to claim 1, wherein the weight ratio of the surfactant, the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, the ethanol, the water and the tetraethoxysilane is 1-5: 5-15: 20-45: 1-10.

4. The method of preparing silica for chemical mechanical polishing according to claim 1, wherein in the step S2, the pH of the mixed solution obtained in the step S1 is adjusted to 8 to 10 with 1% tetramethylammonium hydroxide.

5. The method of preparing silica for chemical mechanical polishing according to claim 1, wherein the stirring speed in the step S1 is 500 to 1000 rpm;

in the step S2, the primary stirring time is 3-7 h, and the stirring speed is 500-1000 rpm; the secondary stirring time is 12-24 h, and the stirring speed is 500-1000 rpm.

6. The method of preparing silicon dioxide for chemical mechanical polishing according to claim 1, wherein the burning temperature in step S2 is 300 to 700 ℃ and the burning time is 1 to 3 hours.

7. A silica produced by the production method according to any one of claims 1 to 6.

8. The silica according to claim 7, wherein the silica is in the form of a solid sphere having a particle diameter of 20 to 100 nm.

9. Use of the silica according to claim 7 for the preparation of a chemical mechanical polishing slurry abrasive.