CN113652200B

CN113652200B - Self-assembled nano silicon dioxide abrasive, polishing solution containing abrasive and application

Info

Publication number: CN113652200B
Application number: CN202110932219.5A
Authority: CN
Inventors: 侯军; 王凯丽
Original assignee: Zhejiang Aoshou Material Technology Co ltd
Current assignee: Zhejiang Aoshou Material Technology Co ltd
Priority date: 2021-08-13
Filing date: 2021-08-13
Publication date: 2022-08-02
Anticipated expiration: 2041-08-13
Also published as: CN113652200A

Abstract

The invention discloses a preparation method of self-assembled nano silicon dioxide, which comprises the following steps of synthesizing silicon dioxide seed liquid and growing silicon dioxide 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 surface appearance of the self-assembled nano silicon dioxide is improved, so that the particles and the wafer form multi-point contact, and the removal rate is improved by a tribochemical reaction; the multiple point contact can effectively disperse the load, make the scratch shallow, and help reduce the probability of scratching. The polishing solution is used for ultra-precise polishing of hard and brittle materials, and the adsorption and dispersion effects of abrasive dust ions or particles are well balanced through the synergistic effect of compounding the dispersing agent and the metal ion capturing agent, so that the polishing solution is easy to clean after polishing.

Description

Self-assembled nano silicon dioxide abrasive, polishing solution containing abrasive and application

Technical Field

The invention relates to a polishing solution based on a self-assembled nano silicon dioxide abrasive, in particular to a self-assembling method of the abrasive, belonging to the technical field of fine chemical engineering.

Background

With the development of the LED industry, chip substrates are gradually developed to large size and high quality. Among them, sapphire wafer is the common substrate slice in current LED industry, sapphire is the general term of alumina single crystal material, has excellent chemical stability, optical transparency and ideal mechanical properties, is often used as the material of optoelectronic components, has gradually reached nanometer level even sub-nanometer level with the processing of electronic devices, and has put forward higher requirements for precision grinding and polishing technology.

The chemical mechanical polishing technology is one of the key technologies for surface processing at present, and is widely applied in the polishing stage of the sapphire crystal wafer. The chemical mechanical polishing effect of the current hard and brittle materials is still not ideal, and the following problems generally exist in the polishing of domestic sapphire substrate slices: (1) the polishing rate is low; (2) the wafer surface has a heavy scratch and needs to be reworked and re-polished. The polishing liquid is a decisive factor in the performance of CMP, and it can influence both the chemical process and the mechanical polishing process. Wherein, the polishing abrasive material is rubbed with the surface of the wafer under the action of pressure, and the material removal rate and the surface quality are directly influenced; the chemical components of the polishing solution determine the chemical reaction processes of surface hydration, chelation and the like, and indirectly affect the surface quality of the wafer, the difficulty of cleaning abrasive dust and the like.

The abrasive commonly used in the polishing of hard and brittle materials at present is SiO ₂ And Al ₂ O ₃ However, among them, the silica abrasive (6 to 7 in Mohs hardness) is low in polishing efficiency because of its lower Mohs hardness than that of the workpiece, so that the polishing time tends to take several hours, which greatly lowers the polishing efficiency, while Al is used ₂ O ₃ The abrasive (with a mohs hardness of about 9) has high hardness, so that nanoparticles are difficult to uniformly disperse and easy to agglomerate, and the wafer is often subjected to rough and deep marks and needs to be reworked.

Disclosure of Invention

In order to solve the technical problems, the invention provides a polishing solution based on a self-assembled nano silicon dioxide abrasive, aiming at improving the surface appearance of spherical silicon dioxide and increasing the removal rate; realize multiple spot contact, reduce the fish tail probability. The invention provides a preparation method of the self-assembled abrasive and polishing solution prepared by using the self-assembled nano silicon dioxide abrasive. The invention prepares a novel silicon dioxide abrasive material through the self-assembly growth of nano particles, and the novel silicon dioxide abrasive material is used for the chemical mechanical polishing of sapphire, silicon carbide, ceramics and other hard and brittle materials. Compared with the spherical silicon dioxide abrasive, the surface appearance of the self-assembled nano silicon dioxide is improved, and the material removal rate is improved by about 50 percent. In the chemical mechanical polishing process, the particles and the wafer form multi-point contact, the friction coefficient is increased, and the removal rate is improved by the friction chemical reaction; multiple point contacts can distribute the load, make the indentation shallower, and help reduce mechanical scratches; in addition, the synergistic effect of the dispersing agent and the metal ion trapping agent in the polishing solution enables the adsorption and dispersion effects of abrasive dust ions or particles to reach good balance, so that the polishing solution is easy to clean after polishing.

The invention provides a method for preparing self-assembled nano silicon dioxide, which comprises the following steps

Step 1, synthesis of silicon dioxide seed liquid:

mixing a PEO-PPO-PEO triblock copolymer (also called F127), 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;

and step 2 growth of silicon dioxide seeds:

heating the silicon dioxide seed liquid to 100 ℃ for boiling (generally 100 ℃), dripping a silicic acid solution (preferably a newly prepared silicic acid solution), and reacting for 1-3 hours.

As a preferred technical solution, the method further comprises the step of pre-preparing spherical silica: mixing the solution containing the silicon precursor and the solution containing the catalyst, and stirring and reacting for 20-30 hours at 40-60 ℃ to obtain spherical silicon dioxide; the weight ratio of the silicon precursor to the catalyst is 150: 3-400: 3; the particle size range of the obtained spherical silicon dioxide is 50-80 nm.

The adsorption of F127 on the surface of the silica particles is a hydrogen bond and is greatly affected by temperature and pH. At 100 ℃, the hydrogen bonds will break and F127 will no longer function as an orientation. The growth of the silicic acid is usually carried out at 100 ℃, the silicic acid is uniformly distributed on the whole seed surface, so that the particles are more compact and firmer, and the appearance of the grinding material before and after grinding is ensured.

As a preferable technical scheme, in the solution containing the silicon precursor in the pre-preparation step and the step 2, the concentration of the silicon precursor is 8-18 wt%; the silicon precursor is selected from at least one of ethyl orthosilicate, methyl orthosilicate, butyltrimethoxysilane, tetraethoxysilane and tetrabutoxysilane; the solvent is water and/or alcohol; the alcohol is at least one selected from anhydrous methanol, anhydrous ethanol, n-propanol, n-butanol, and isobutanol.

As a preferable technical scheme, in the solution containing the catalyst in the pre-preparation step and the step 2, the concentration of the catalyst is 0.1-0.2 wt%; the catalyst is at least one of arginine, urea, triethylamine and lysine; the solvent is water.

As a preferable technical scheme, in the step 1, the concentration of a silicon precursor in the solution A is 8-11 wt%; in the step 1, the weight ratio of the PEO-PPO-PEO triblock copolymer to the spherical silicon dioxide to the catalyst to the silicon precursor is 40:50:900: 300-55: 65:1100: 500; the concentration of the silicon dioxide in the solution containing the spherical silicon dioxide is 3 to 6 weight percent; the solvent in the solution is water and/or alcohol.

As a preferable technical scheme, in the step 2, the pH value of the reaction system is regulated to 9-11; the speed of dropping the silicic acid solution is 10-35 g/min; the solid content of the silicic acid solution is 1 to 4 weight percent; the content of silicon dioxide in the silicon dioxide seed liquid is 3 to 6 weight percent; the weight ratio of the silicon dioxide seed solution to the silicic acid solution is 1: 1-1: 10.

The invention also provides the self-assembly nano silicon dioxide prepared by any method, the micro appearance of the self-assembly nano silicon dioxide is a sphere, and the particle size of the sphere is 60 nm-100 nm (the particle size of the sphere after deposition); the outer surface of the sphere is discretely deposited with silica.

As a preferred technical scheme, the self-assembled nano silicon dioxide is used as an abrasive for chemical mechanical polishing, and a polishing substrate is preferably sapphire, silicon carbide or ceramic.

In another aspect, the invention provides a polishing solution containing any of the self-assembled nano-silica materials described above.

As a preferred technical scheme, the polishing solution comprises the following components in parts by weight:

the self-assembled nano silicon dioxide: 20-40 parts;

surfactant (b): 0.5-5 parts;

dispersing agent: 0.1-5 parts;

metal ion scavenger: 0.1-5 parts;

pH regulator: 1-10 parts;

deionized water: 52-70 parts of a binder;

preferably, the metal ion scavenger is at least one selected from glycine, lysine, aminotrimethylenephosphonic Acid (ATMP), triethylenetetraethylenediamine tetramethylenephosphonic acid (EDTMPA), and sodium ethylenediamine diphenylacetate (EDDHA-Na); preferably sodium ethylenediamine-di-o-phenyl acetate.

Preferably, the dispersant is selected from at least one of polyacrylate, polycarboxylate and block phosphate polymer; polyacrylates or polyammonium salts are preferred.

Preferably, the surfactant is selected from at least one of polyoxyethylene alkylamine, polyoxyethylene alkylolamide, polyacetylene alcohol or fatty alcohol polyether; polyoxyethylene alkylamines are preferred.

Preferably, the pH regulator is at least one selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide; triethanolamine is preferred.

According to another technical scheme of the invention, the application of the self-assembled nano silicon dioxide or the polishing solution is provided, the self-assembled nano silicon dioxide or the polishing solution is used for chemical mechanical polishing, and preferably, a polishing substrate is sapphire, silicon carbide or ceramic.

The invention can produce the beneficial effects that:

(1) according to the preparation method of the self-assembled nano silicon dioxide abrasive for ultra-precision polishing of the hard and brittle material, provided by the invention, the surface appearance of the abrasive is improved, so that particles and a wafer form multi-point contact, and the removal rate is improved by a tribochemical reaction; the multiple point contact can effectively disperse the load, make the scratch shallow, and help reduce the probability of scratching.

(2) The polishing solution of the self-assembled nano silicon dioxide abrasive for ultra-precision polishing of the hard and brittle material, provided by the invention, has the advantages that the adsorption and dispersion effects of abrasive dust ions or particles are well balanced through the compound synergistic effect of the dispersing agent and the metal ion trapping agent, and the polishing solution is easy to clean after polishing.

Description of the drawings:

FIG. 1: SEM of spherical silica abrasives prepared in comparative examples 1 to 3;

FIG. 2: SEM of the self-assembled nano silica abrasive prepared in preparation example 1;

FIG. 3: the preparation principle of the self-assembled nano silicon dioxide is shown schematically;

FIG. 4 is a schematic view of: schematic diagram of microcontacts.

The specific implementation mode is as follows:

the present application will be described in detail with reference to examples, but the present application is not limited to these examples.

Unless otherwise specified, the raw materials in the examples of the present application were purchased commercially except for the self-assembled nano silica abrasive as synthesized.

Preparation example 1

The preparation method of the self-assembled nano silicon dioxide abrasive material comprises the following specific steps:

pre-preparation: synthesis of Silica Nanospheres (SNS).

0.3g of arginine was first dissolved in 200g of water, and then 40g of Tetraethylorthosilicate (TEOS) was added. Stirring the two-phase reaction in a water bath at the speed of 500rpm, reacting for 24 hours at the reaction temperature of 60 ℃ to obtain the spherical silicon dioxide abrasive with the particle size range of 50-80 nm;

step 1: and (3) synthesizing a silicon dioxide nanosphere (SNS) seed liquid.

100g of pre-prepared spherical silica was taken out, water (300g), arginine (0.48g) and F127 (PEO-PPO-PEO triblock copolymer, 5.5g) were added in sequence, and 40g TEOS was added. The reaction is stirred in a water bath at 60 ℃ for 24 hours, and the obtained blue transparent liquid is silicon dioxide (SNS) seed liquid.

Step 2: by further growth of the seeds, seed meal is prepared.

First, SNS seed solution (200g) prepared in step 1, which contains silica in an amount of 4wt%, was poured into a 2L four-necked flask, water (300g) was added thereto, and heated to boil at 100 ℃ with vigorous stirring. Then, a silicic acid solution (1400g, solid content: 2.5%) prepared by an ion exchange method was slowly added dropwise (controlled at a rate of 10 to 35 g/min). During the reaction, the liquid level was kept constant by controlling the addition of the silicic acid solution and the evaporation rate of water. Simultaneously adding 1wt% of sodium hydroxide solution to ensure that the pH value of the reaction system is 9-11. After complete addition of the silicic acid solution, the reaction was continued for 1h and then cooled to room temperature. Non-smooth, self-assembled nanosilica abrasives having particle sizes of 60-90nm were successfully prepared, as shown in FIG. 2. As can be seen from the electron micrograph of FIG. 2, the self-assembled nano-silica prepared by the invention is a sphere with a convex surface, and the number of contact sites is more than that of the spherical silica with a smooth surface.

As shown in fig. 3, the self-assembled nano silica abrasive is prepared by growing silica on the surface of spherical silica; as shown in FIG. 4, which is a schematic diagram of a microcontact, it can be seen that the self-assembled nano-silica prepared by the present invention has more contact points compared with spherical silica, and is more favorable for reducing scratches on the polished surface.

Example 1

A polishing solution based on a self-assembled nano silicon dioxide abrasive comprises the following components in parts by weight:

self-assembled nano silica (the final non-smooth self-assembled nano silica abrasive prepared through the pre-preparation, the step 1 and the step 2 in the preparation example 1): 20 parts of (1);

dispersing agent: 0.1 part of polymethyl acrylate (molecular weight is 4 ten thousand);

metal ion scavenger: 0.1 part of ethylenediamine-di-o-phenyl sodium acetate (EDDHA-Na);

surfactant (b): 0.5 part of polyoxyethylene alkylamine;

pH regulator: 1 part of triethanolamine;

deionized water: 78.3 portions.

The preparation method of the polishing solution comprises the following steps:

1) weighing 78.3 parts of deionized water according to the components of the formula;

2) adding 20 parts of self-assembled nano silicon dioxide abrasive into deionized water, and stirring at 150rpm for 10 min;

3) adding 1 part of triethanolamine into the mixture obtained in the step 2), and stirring at 200rpm for 10 min;

4) adding 0.1 part of polymethyl acrylate (molecular weight is 4 ten thousand) dispersing agent into the mixture in the step 3), and stirring at 200rpm for 5 min;

5) adding 0.1 part of ethylenediamine-dipheny-phenyl sodium acetate into the mixture in the step 4), and stirring at 200rpm for 5 min;

6) 0.5 part of polyoxyethylenealkylamine was added to the above 5), and the mixture was stirred at 200rpm for 5 minutes.

Examples 2 to 19, comparative examples 1 to 5

The components and mass contents of the polishing solutions of examples 2 to 19 of the present invention and the polishing solutions of comparative examples 1 to 5 are shown in Table 1.

The polishing slurry was prepared in the same manner as in example 1.

TABLE 1 examples 2-19 and comparative examples 1-5

The spherical silica abrasives of comparative examples 1 to 3 were the spherical silica abrasives prepared in advance in preparation example 1.

As shown in FIG. 1, the scanning electron microscope images of the spherical silica abrasives synthesized in the pre-preparation steps of comparative examples 1 to 3 show that the spherical silica abrasives with uniform size are successfully synthesized by the pre-preparation method.

The above-mentioned examples were prepared according to the specific preparation procedure of the above-mentioned polishing solutions.

The polishing experiment parameters of the performance test I, the performance test II and the performance test III are as follows:

polishing experimental conditions of the polishing solution:

polishing the machine table: precision single-side grinder (EL-380)

Polishing the pad: polyurethane polishing pad with disc diameter of 60cm

Polishing head: three polishing heads, each polishing head fixes the sapphire sheet on the ceramic disc through a ceramic correction ring

Polishing pressure: 15 kg/head

Polishing time: 2h

The rotating speed of the polishing disc is as follows: 60rpm

Flow rate of polishing solution: 60ml/min

Temperature of the surface of the polishing disc: 20-30 ℃ and starting a circulating water cooler

Diluting and proportioning: stock solution/water 1/10

Polishing solution: the polishing solutions obtained in the above examples were tested.

Performance test I evaluation of material removal rate:

there are generally two methods of detecting material removal rate: direct and indirect processes. The inventor adopts a method of measuring the quality of the substrate before and after polishing and indirectly calculating the thickness of the removed sapphire layer according to the density and the area of the substrate. The method has the greatest characteristic of simple and convenient measurement, and the removal rate can be rapidly obtained. The evaluation of the material removal rate in the examples of the present application is as follows:

MRR＝Δm/(ρSt)

wherein: and Δ m is the mass change before and after sapphire polishing, ρ is the sapphire density, S is the circular area of the sapphire wafer, and t is the polishing time.

Performance test II evaluation of surface cleanliness:

the polishing solution is used for cleaning polished wafers by using deionized water after a sapphire substrate is subjected to polishing and grinding test, and the easy cleaning degree of abrasive dust on the surfaces and edges of the wafers is observed.

Performance test iii surface roughness evaluation:

the polished sapphire sheet was subjected to surface roughness measurement using a surface roughness measuring instrument (manufacturer: Sanfeng model: SR 2000).

The removal rate, roughness and crystal face cleanliness after lapping and polishing water of the sapphire substrates after polishing in examples 1 to 19 and comparative examples 1 to 5 are shown in table 2 below.

TABLE 2 polishing effects of examples 1-19 and comparative examples 1-5

The comparison of the data in table 2 shows that, compared with the common spherical silicon dioxide abrasive, the surface morphology of the self-assembled silicon dioxide is improved, contact sites between particles and wafers are increased in the polishing process, the friction coefficient is increased, the tribochemical reaction is facilitated, and the material removal rate is improved by about 2 times; the multi-point contact can effectively disperse the load, so that the indentation becomes shallow, the scratching probability is reduced, and the surface roughness of the wafer is reduced; in addition, the synergistic effect of the dispersing agent and the metal ion trapping agent in the polishing solution enables the adsorption and dispersion of abrasive dust ions or particles to be well balanced, and the polishing solution has the advantages of being easy to clean after polishing and the like.

Although the present application has been described with reference to a few embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the application as defined by the appended claims.

Claims

1. The polishing solution is characterized by comprising the following components in parts by weight:

self-assembling nano silicon dioxide: 20-40 parts;

surfactant (b): 0.5-5 parts;

dispersing agent: 0.1-5 parts;

metal ion scavenger: 0.1-5 parts;

pH regulator: 1-10 parts;

deionized water: 52-70 parts of a binder;

the dispersant is selected from at least one of polyacrylate, polycarboxylate and block phosphate polymer;

the metal ion trapping agent is at least one selected from glycine, lysine, amino trimethylene phosphonic acid, triethylene tetramethlene diamine tetramethylene phosphonic acid and ethylenediamine dipheny sodium acetate;

the microscopic appearance of the self-assembled nano silicon dioxide is spherical, and the particle size of the spherical is 60 nm-100 nm; discretely depositing silicon dioxide on the outer surface of the sphere;

the preparation method of the self-assembled nano silicon dioxide comprises the following steps

Step 1, synthesis of silicon dioxide seed liquid:

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;

and step 2 growth of silicon dioxide seeds:

heating the silicon dioxide seed liquid to boiling, dripping a silicic acid solution, and reacting for 1-3 hours.

2. The polishing solution according to claim 1, wherein the preparation method of the self-assembled nano silica further comprises the step of pre-preparing spherical silica:

mixing the solution containing the silicon precursor and the solution containing the catalyst, and stirring and reacting for 20-30 hours at 40-60 ℃ to obtain spherical silicon dioxide;

the weight ratio of the silicon precursor to the catalyst is 150: 3-400: 3;

the particle size range of the obtained spherical silicon dioxide is 50-80 nm.

3. The polishing solution according to claim 2,

in the solution containing the silicon precursor in the pre-preparation step and the step 1, the concentration of the silicon precursor is 8-18 wt%; the silicon precursor is selected from at least one of ethyl orthosilicate, methyl orthosilicate, butyltrimethoxysilane, tetraethoxysilane and tetrabutoxysilane; the solvent is water and/or alcohol; the alcohol is at least one selected from anhydrous methanol, anhydrous ethanol, n-propanol, n-butanol, and isobutanol.

4. The polishing solution according to claim 2,

in the solution containing the catalyst in the pre-preparation step and the step 1, the concentration of the catalyst is 0.1-0.2 wt%; the catalyst is at least one of arginine, urea, triethylamine and lysine; the solvent is water.

5. The polishing solution according to claim 1,

in the step 1, in the solution A, the concentration of a silicon precursor is 8-11 wt%;

in the step 1, the weight ratio of the PEO-PPO-PEO triblock copolymer to the nano-silica to the catalyst to the silicon precursor is 40:50:900: 300-55: 65:1100: 500;

the concentration of the spherical silica in the solution containing the spherical silica is 3 to 6 weight percent; the solvent in the solution is water and/or alcohol.

6. The polishing solution according to claim 1,

in the step 2, regulating and controlling the pH value of the reaction system to be 9-11; the speed of dropping the silicic acid solution is 10-35 g/min; the solid content of the silicic acid solution is 1-4 wt%;

the content of silicon dioxide in the silicon dioxide seed liquid is 3-6 wt%;

the weight ratio of the silicon dioxide seed solution to the silicic acid solution is 1: 1-1: 10.

7. The polishing solution according to claim 1,

the surfactant is selected from at least one of polyoxyethylene alkylamine, polyoxyethylene alkylolamide, polyacetylene alcohol or fatty alcohol polyether.

8. The polishing solution according to claim 1,

the pH regulator is at least one selected from ethanolamine, diethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide.

9. Use of the polishing solution according to any one of claims 1 to 8 for chemical mechanical polishing.

10. Use according to claim 9, wherein the polishing liquid is used for polishing of a polishing substrate, the polishing substrate being sapphire, silicon carbide or ceramic.