CN106867413B

CN106867413B - High-concentration cerium oxide polishing solution and preparation method thereof

Info

Publication number: CN106867413B
Application number: CN201710064997.0A
Authority: CN
Inventors: 赵艳; 陈选伟; 戚祖强
Original assignee: Baotou Jiemingna Optoelectronics Technology Co ltd
Current assignee: Baotou Jiemingna Optoelectronics Technology Co ltd
Priority date: 2017-02-06
Filing date: 2017-02-06
Publication date: 2021-06-04
Anticipated expiration: 2037-02-06
Also published as: CN106867413A

Abstract

The invention relates to a high-concentration cerium oxide polishing solution and a preparation method thereof, wherein the polishing solution is a water suspension and comprises the following components in percentage by mass: 40 to 60 percent of cerium oxide, 0.02 to 0.5 percent of dispersant, 0.5 to 5 percent of stabilizer, 0.06 to 1 percent of thickener, 0.1 to 2 percent of chelating agent, 0.25 to 5 percent of lubricant, 0.05 to 0.5 percent of bactericide, organic base regulator and the balance of deionized water. According to the invention, xanthan gum and CMC are compounded to be used as a thickening agent, so that cerium oxide particles can be suspended in the polishing solution for a long time, and silica sol is used as a stabilizing agent, so that the agglomeration of the cerium oxide particles can be reduced through the interaction between the cerium oxide particles and the xanthan gum, the cerium oxide particles are not hardened at the bottom of the polishing solution, and the redispersibility of the cerium oxide particles is enhanced. The polishing composition is suitable for polishing liquid crystal glass substrates, mobile phone cover plate glass, optical glass elements and the like, and has the advantages of large cutting force, good surface quality and easiness in cleaning after polishing.

Description

High-concentration cerium oxide polishing solution and preparation method thereof

Technical Field

The invention belongs to the technical field of materials, and particularly relates to a high-concentration cerium oxide polishing solution and a preparation method thereof.

Background

China has abundant rare earth resources, the storage capacity of industrial cerium resources is about 1800 ten thousand tons, and cerium oxide polishing materials have the advantages of strong cutting capability, short polishing time, high polishing precision, clean operating environment and the like, so that the cerium oxide polishing materials are applied to many aspects, such as polishing of lenses, optical fibers, optical elements, silicon wafers, ITO glass, mobile phone glass, aviation glass, integrated circuit substrates and the like, and become one of important materials for chemical mechanical polishing.

At present, almost all polishing solutions adopted in the production of integrated circuits in China are imported, the domestic production is less, however, the selling price of the imported polishing solutions is high, so that the production cost of chips is increased, and particularly, cerium salt raw materials are imported from China by foreign enterprises and are processed and prepared into the polishing solutions to be sold to people. Domestic enterprises mainly produce polishing powder and few enterprises can produce polishing solution with good suspension stability. The domestic production of the polishing solution has the problems of low polishing efficiency, poor surface quality and the like due to poor dispersion stability and hardened and agglomerated cerium oxide particles. When preparing a high-concentration cerium oxide polishing solution, the polishing solution is required to have excellent suspension property and redispersibility (no obvious hardening condition at the bottom of the polishing solution). The rare earth polishing powder has good suspension property and redispersibility, has better polishing efficiency and can obtain better surface quality compared with the traditional rare earth polishing powder. The invention is beneficial to improving the product structure of polishing powder enterprises and improving the added value of rare earth products.

Disclosure of Invention

The invention aims to provide a high-concentration cerium oxide polishing solution to solve the defects of poor suspension and redispersibility, low removal rate, poor surface quality, serious environmental pollution and the like in the prior art.

The technical scheme for solving the technical problems comprises the following steps: the high-concentration cerium oxide polishing solution is provided, is an aqueous suspension and comprises the following components in percentage by mass:

the cerium oxide powder of the present invention has a particle size of 0.6 to 0.8 um.

The dispersant is one of sodium polyacrylate, ammonium polyacrylate and potassium polyacrylate. Polyacrylate is an anionic polymer electrolyte, has a polymer chain with a certain length, can play a role in steric stabilization, has charges carried by the polyacrylate and can play a role in electrostatic stabilization, so that the polyacrylate has excellent dispersing performance, and polyacrylate with low molecular weight is generally adopted as a dispersing agent. In some reports, sodium hexametaphosphate was used as a dispersant for cerium oxide, and six sodium phosphates were structurally characterized by the hydrophilic group-POO^-And the hydrophilic group of the polyacrylate is-COO^-The latter is more hydrophilic than the former, the more hydrophilic, the stronger the adsorptivity; in addition, sodium hexametaphosphate is a rigid structure, polyacrylate is a C chain, the C chain is flexible and can rotate freely, the sodium hexametaphosphate is easy to adsorb than rigid, and the sodium hexametaphosphate is easy to hydrolyze into phosphate after being placed in water for a long time, and the dispersion effect can be gradually reduced along with the increase of the hydrolysis degreeWeak, and polyacrylic acid salts do not. Therefore, the polyacrylate is used as a dispersant, so that the solid content of the abrasive and the stability of the dispersion system can be improved.

The stabilizing agent is nano silica sol, the silica sol generates negative adsorption to free particles in the suspension through colloidal particles, a vacancy layer is formed on the surface of cerium oxide particles, and stable dispersion of the suspension is realized due to the vacancy stabilizing effect. And because the silica sol is a colloid with negative electricity, the larger the negative electricity, the more vacancies are formed on the surfaces of the cerium oxide particles, the fewer the chances of the cerium oxide particles in contact with each other before, and the better the stability of the suspension, thereby effectively preventing the cerium oxide from hardening at the bottom of the suspension. The invention adopts silica sol with small grain diameter, and has low price and good dispersibility.

The thickening agent is compounded by xanthan gum and sodium carboxymethylcellulose, xanthan gum molecules are pentasaccharide repeating units formed by D-glucose, D-mannose, D-glucuronic acid, acetic acid and pyruvic acid, and are water-soluble biopolymer polymers, side chains in microstructures are combined with a main chain through hydrogen bonds to form a double-spiral structure, the double-spiral structure exists in a state of a multiple-spiral polymer, and the side chains of the xanthan gum molecules are negative charges of glucuronic acid base bands. The CMC also has a negative charge on the side chain, and when the xanthan gum reaches a certain amount, the suspension property of the cerium oxide particles may be enhanced due to the enhancement of electrostatic repulsive force between xanthan gum molecules and CMC molecules.

The chelating agent is one of ethylene diamine tetramethylene phosphonic acid sodium, hydroxyethylidene diphosphonic acid tetrasodium hydroxyethylidene diphosphonic acid and aminotrimethylene phosphonic acid tetrasodium. The organic phosphorus salts are adopted as the chelating agent, so that the method has the following advantages: 1) it can form stable complex with various metal ions, and reduce the pollution of the metal ions to a polishing solution system; 2) the polishing machine has a certain cleaning function, and is beneficial to cleaning a polished workpiece; 3) it is also a corrosion inhibitor at the same time, can protect the surface of the machine tool; 4) is stable at high pH value and high temperature, is not easy to hydrolyze and is easy to biodegrade.

The organic base regulator is one of ethanolamine, triethanolamine, ethylenediamine, hydroxyethyl ethylenediamine and tetramethyl ammonium hydroxide, and the pH value of the grinding liquid is 7-9. The use of organic base to adjust the pH prevents metal ion contamination caused by inorganic base adjustment, and it has been reported that the polishing efficiency of cerium oxide particles is better under alkaline conditions.

The lubricant is one or more of glycol and glycerol. The glycol or the glycerol is used as the lubricant, so that the xanthan gum can be better dissolved, the optimal thickening effect of the xanthan gum can be exerted, and the glycol or the glycerol can also be used as the lubricant to prevent the damage of workpieces caused by excessive continuous mechanical action in the polishing process.

The bactericide is 1, 2-benzisothiazolin-3-one (BIT), is a broad-spectrum bactericide (bacteriostatic) agent, and has the advantages of good water solubility, low toxicity, no formaldehyde or formaldehyde release, easy degradation and the like.

Drawings

FIG. 1 is a two-dimensional AFM image of ITO glass after polishing in example 1;

FIG. 2 is a two-dimensional AFM image of ITO glass after polishing of comparative example 1;

FIG. 3 is a two-dimensional AFM image of ITO glass after polishing of comparative example 2;

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments.

In a preferred embodiment of the present invention, the high concentration cerium oxide polishing solution is an aqueous suspension, and comprises the following components by mass:

in another preferred embodiment of the present invention, the polishing solution has the above components by weight, and particularly, the size of the cerium oxide particles is 0.6 to 0.8 um. The cerium oxide is preferably 45 to 55 mass%.

In another preferred embodiment provided by the present invention, the dispersant is one of sodium polyacrylate, ammonium polyacrylate and potassium polyacrylate. The preferable mass percentage of the dispersant is 0.05-0.2%.

In another preferred embodiment of the present invention, the stabilizer is a nano silica sol. The preferable mass percentage of the stabilizer is 1-3%.

In another preferred embodiment provided by the invention, the thickener is a xanthan gum compounded with sodium carboxymethyl cellulose. The preferable mass percentage of the thickening agent, xanthan gum is 0.1-0.5%; the preferred mass percentage of the sodium carboxymethylcellulose is 0.05-0.2%.

In another preferred embodiment of the present invention, the chelating agent is one of ethylenediamine tetramethylene phosphonic acid sodium, hydroxyethylidene diphosphonic acid tetrasodium hydroxyethylidene diphosphonic acid, and aminotrimethylene phosphonic acid tetrasodium. The preferable mass percentage of the chelating agent is 0.2-1%.

In another preferred embodiment provided by the present invention, the lubricant is one or more of ethylene glycol and glycerol. The preferable mass percentage of the lubricant is 0.5-2%.

In another preferred embodiment provided by the present invention, the organic base modifier is one of ethanolamine, triethanolamine, ethylenediamine, hydroxyethylethylenediamine and tetramethylammonium hydroxide, and preferably has a pH value of 7-8.

In another preferred embodiment provided by the present invention, the germicide is 1, 2-benzisothiazolin-3-one (BIT). The preferable mass percentage of the bactericide is 0.5-0.1%.

Examples 1-6, comparative example 1 (commercially available cerium oxide powder), comparative example 2 (commercially available cerium oxide polishing solution)

1. Formulation of polishing compositions

1) Fully dissolving xanthan gum with lubricant (ethylene glycol, glycerol) for use; 2) dissolving CMC with proper amount of deionized water; 3) dispersing cerium oxide particles by using the residual deionized water to obtain a suspension; 4) under the condition of mechanical stirring, sequentially adding a dispersing agent, a stabilizing agent, a chelating agent, a bactericide, an organic base pH regulator and 1)2) the obtained thickening agent into the cerium oxide suspension, and uniformly stirring to obtain the cerium oxide polishing solution, wherein the specific ratio is shown in table 1.

2. Polishing contrast test:

using the cerium oxide suspensions of examples 1 to 6 of the present invention, comparative example 1 (commercially available cerium oxide powder), and comparative example 2 (commercially available cerium oxide polishing liquid), 4-inch ITO glass was subjected to chemical mechanical polishing. The polishing equipment is a Retc instruments RBPo-6 type polishing machine, and the polishing process comprises the following steps: the specific gravity of the polishing solution is 1.08, the pressure is 0.02MPa, the upper disc rotating speed is 20rpm, the lower disc rotating speed is 60rpm, the flow rate is 120mL/min, and the time is 25 min.

TABLE 1 ingredient ratios in examples 1-6

3. Grinding evaluation criteria:

1) removal rate

And after polishing, ultrasonically cleaning and drying the ITO glass by using a cleaning agent, and then detecting the surface quality and the polishing rate of the ITO glass. Measuring the mass difference before and after polishing by using a precision balance, and evaluating the removal rate;

2) surface quality after polishing

And detecting the surface roughness of the polished ITO glass by using an atomic force microscope.

The test results are shown in table 2:

TABLE 2 Experimental results of examples and comparative examples

4. And (3) suspension rate determination:

reduction of specific gravity of the polishing solution (dilution solution) during polishing: the above 1-6 examples and comparative examples 1-2 were weighed to obtain appropriate amount of sample, and the suspension with specific gravity of 1.08 was used for polishing ITO glass, and the suspension was sampled every 2 hours (total 8 hours), and the experimental results are shown in Table 3.

The specific gravity of the polishing solution decreases (diluted solution) when the polishing solution is placed and observed: an appropriate amount of the sample was weighed in the above examples 1 to 6 and comparative examples 1 to 2, and placed in a measuring cylinder containing 250mL (30. + -. 2 ℃ C.), deionized water was added to the sample, the specific gravity was adjusted to 1.08, and the sample was placed to observe the decrease of the specific gravity, and the experimental results are shown in Table 3.

Standing and observing, wherein the suspension property and the redispersibility of the concentrated solution are as follows: examples 1-6 and example 2 above were placed in a 250mL stoppered cylinder and example 1 was formulated as a 45% solids suspension in a 250mL stoppered cylinder. The above 8 samples were prepared in duplicate for each sample: one part is placed for a certain time, the supernatant and the sedimentation layering liquid level are observed, and the experimental result is shown in table 4; the hardened condition of the bottom (turning the measuring cylinder upside down to see whether the bottom of the measuring cylinder is hardened) is observed in one part, and the experimental results are shown in table 5.

It is to be understood that the above-described embodiments are only a few, and not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

TABLE 3 results of polishing suspension test of examples and comparative examples

TABLE 4 results of suspension property test of examples and comparative examples

TABLE 5 results of redispersibility test of examples and comparative examples

Claims

1. The high-concentration cerium oxide polishing solution is characterized in that the polishing solution is a water suspension and comprises the following components in percentage by mass:

40-60% of cerium oxide, 0.02-0.5% of dispersing agent, 0.5-5% of stabilizing agent, 0.06-1% of thickening agent, 0.1-2% of chelating agent, 0.25-3% of lubricating agent, 0.05-0.5% of bactericide, organic base regulator and the balance of deionized water;

the size of the cerium oxide particles is 0.6-0.8 mu m;

the dispersant is sodium polyacrylate PAAS and ammonium polyacrylate PAA-NH₄One of potassium polyacrylate K-PAM;

the stabilizer is nano silica sol;

the thickening agent is formed by compounding xanthan gum and sodium carboxymethyl cellulose (CMC);

the chelating agent is one of amino trimethylene phosphonic acid tetrasodium ATMP.4 Na, hydroxy ethylidene diphosphonic acid tetrasodium HEDP.4 Na and ethylene diamine tetramethylene phosphonic acid sodium EDTMPS;

the lubricant is glycerol;

the organic base regulator is one of ethanolamine, triethanolamine, ethylenediamine, hydroxyethyl ethylenediamine AEEA and tetramethyl ammonium hydroxide.

2. A method for preparing the high-concentration cerium oxide polishing solution according to claim 1, wherein:

1) dissolving xanthan gum with glycerol;

2) dissolving CMC with proper amount of deionized water;

3) dispersing cerium oxide particles by using the residual deionized water to obtain a suspension;

4) under the condition of mechanical stirring, sequentially adding a dispersing agent, a stabilizing agent, a chelating agent, a bactericide, an organic base pH regulator and the thickening agents obtained in steps 1) and 2) into the cerium oxide suspension, and uniformly stirring to obtain the cerium oxide polishing solution.