CN104946202A - Iron-doped silica sol composite abrasive grain, and polishing solution composition and preparation method thereof - Google Patents

Abstract

The invention relates to an iron-doped silica sol composite abrasive grain, and a polishing solution composition and a preparation method thereof. The preparation method of the composite abrasive grain comprises the following steps: adding a 0.29 wt% ferric chloride solution and a 2-3 wt% dilute silicic acid solution in a mass ratio of 1:1 into a silica crystal seed under certain reaction conditions, and doping the iron element into the silica sol abrasive grain in the silica sol growth process to form the uniform stable iron-doped silica sol composite abrasive grain, wherein the doping mass percent is 0.1-5.0%. The physical structure of the composite abrasive grain is nano spherical. The chemical composition of the abrasive grain contains the iron element capable of performing chemical actions with the sapphire and silicon chip surface, thereby enhancing the polishing rate. When being used for polishing the sapphire substrate and silicon chip, the polishing solution provided by the invention can effectively lower the surface roughness and microroughness of the sapphire and silicon chip and enhance the polishing rate of the sapphire and silicon chip.

Description

Iron-doped silica sol composite abrasive grain, its polishing liquid composition and its preparation method

technical field

The present invention relates to a polishing abrasive grain, a polishing liquid composition and a preparation method thereof, in particular to a preparation method of an iron-doped silica sol composite abrasive grain and the technical field of raw material surface grinding and polishing.

Background technique

Due to its high Mohs hardness and good chemical stability, sapphire material is widely used in electrical, optical and other fields. In the field of optoelectronics, light-emitting diodes (LEDs) have simple advantages such as low operating voltage, low power consumption, high efficiency, long life, solidification, fast response speed, and drive circuits, and are recognized as the most promising high-tech in the 21st century. one of the fields. Sapphire is used as a substrate material for LEDs because of its good high temperature stability and mechanical properties. The surface quality of sapphire has a very important impact on the performance and quality of LED devices. At present, it is required to be ultra-smooth, defect-free, and roughness less than 0.2nm. Therefore, the final polishing process of sapphire has high requirements and becomes the most important process.

At present, chemical mechanical polishing (CMP) technology is generally used to precisely polish the surface of sapphire devices. Abrasive grains are the main component of chemical mechanical polishing fluids. At present, the abrasive grains widely used in practice are usually traditional inorganic particles such as silicon oxide and aluminum oxide. The polishing effect of silicon oxide abrasive grains on sapphire is better, but there are some problems in the CMP polishing process, such as low polishing rate resulting in low production efficiency, and the surface quality needs to be further improved. Therefore, we improve the removal rate by changing the characteristics of the abrasive particles in the polishing fluid.

Contents of the invention

One of the objectives of the present invention is to provide an iron-doped silica sol composite abrasive grain.

The second object of the present invention is to provide a polishing liquid composition using the composite abrasive grain.

In order to achieve the above object, the present invention adopts the following technical solutions.

An iron-doped silica sol composite abrasive grain of the present invention is characterized in that it has the following composition

Iron element compound (iron hydroxide) 0.1-5 wt.%;

Silica sol 99.9-95 wt.%.

A method for preparing iron element-doped silica sol composite abrasive grains of the present invention is characterized in that it has the following processes and steps:

a. Pass the mass fraction of 8.0% water glass through the cation exchange resin, and receive the outflowing liquid when the pH value of the outflowing liquid is between 2.5-3.5, then the mass fraction is 2.0-3.0% active silicic acid solution;

b. Under stirring at 100°C, add 750-3000 grams of 0.29% ferric chloride solution and 750-3000 grams of 2.0-3.0% active silicic acid solution to 3000 grams of 10% ferric chloride solution In the seed silicon oxide solution, dropwise add a sodium hydroxide solution with a mass fraction of 0.4% at the same time, control the dropping rate, keep the liquid level of the silicon oxide seed crystal mother liquor basically unchanged, and control the pH range between 9.0-11.0;

c. Control the rate of dripping and water evaporation, so that the liquid level of the mother liquor remains basically unchanged until the mixed solution is dripped. After half an hour of reaction, turn off the heater, stir and cool down to room temperature; that is, the iron element doped silica sol Composite abrasive grains.

A kind of polishing fluid composition of the present invention is characterized in that having following composition:

a. Iron-doped silica sol composite abrasive grains 6-6.12 wt.%,

b. Dispersant sodium hexametaphosphate 2 wt.%,

c. deionized water balance;

d. The sum of the mass percentages of the above components is 100 wt.%.

A kind of preparation method of polishing fluid composition of the present invention is characterized in that having following process and step:

a. Pass the above-mentioned iron-doped silica sol composite abrasive solution through a 350-mesh filter to remove large particles;

b. add deionized water to it and be mixed with 5 liters of solutions;

c. Then add 100 grams of sodium hexametaphosphate as a dispersant, and stir evenly to obtain a polishing liquid composition.

The physical structure of the composite abrasive grains of the invention is nano-spherical, and the chemical composition of the abrasive grains contains iron element, which can improve the chemical action of the abrasive grains. The chemical action can increase the polishing rate of the abrasive grain and increase the material removal rate.

The polishing solution provided by the invention is used to polish sapphire substrates and silicon wafers, which can effectively reduce the surface roughness of the sapphire and silicon wafers and increase the removal rate of the sapphire and silicon wafer surfaces.

Detailed ways

Specific embodiments of the present invention are summarized below.

Example 1

The iron-doped silica sol composite abrasive grains of the present invention can be prepared by a co-precipitation method. The preparation process is as follows: in the process of preparing the silica sol by the ion exchange method, the iron element is doped into the silica sol particles by co-precipitation. Pass the water glass with a mass fraction of 8.0% through the cation exchange resin, and receive the outflowing liquid when the pH value of the outflowing liquid is between 2.5-3.5, and then obtain a mass fraction of 2.0-3.0% active silicic acid solution; at 100°C and Under stirring, add 750 grams of ferric chloride solution with a mass fraction of 0.29% and 750 grams of an active silicic acid solution with a mass fraction of 2.0-3.0% into 3000 grams of a 10% seed crystal silica solution, and dropwise A sodium hydroxide solution with a mass fraction of 0.4% is used to control the dropping rate, to keep the liquid level of the silicon oxide seed crystal mother liquor basically unchanged, and to control the pH range between 9.0-11.0. The reaction continues until the mixture of iron ions and active silicic acid is added dropwise, the reaction is over, stop heating, continue to stir until the solution reaches room temperature, and then pour it into a beaker to obtain a composite mill of iron element doped silica sol. particle solution. Before polishing, pass the composite abrasive solution through a 350-mesh sieve, add deionized water to prepare 5 liters of polishing liquid, then add 100 g of dispersant sodium hexametaphosphate, and stir evenly. The obtained solution is the polishing solution doped with iron element doped silica sol composite abrasive grains with a mass ratio of 0.48%.

Doping mass ratio is 0.48 % The composition and mass percentage of iron-doped colloidal silicon oxide composite abrasive polishing fluid are as follows:

Iron doped silica sol composite abrasive grains 6.02 wt.%

Dispersant sodium hexametaphosphate 2 wt.%

Deionized water 91.98 wt.%

Example 2

1500g of ferric chloride solution with a mass fraction of 0.29% and 1500g of a mass fraction of 2.0-3.0% active silicic acid solution are used. Finally, a polishing solution doped with iron element-doped silica sol composite abrasive grains with a mass ratio of 0.96% was obtained.

The doping mass ratio is 0.96 % The composition and mass percentage of the iron-doped colloidal silicon oxide composite abrasive polishing fluid are as follows:

Iron-doped silica sol composite abrasive grains 6.06 wt.%

Dispersant sodium hexametaphosphate 2 wt.%

Deionized water 91.94 wt.%

Example 3

Use 3000g of ferric chloride solution with a mass fraction of 0.29% and 3000g of a mass fraction of 2.0-3.0% active silicic acid solution to mix evenly. Finally, a polishing fluid doped with iron element doped silica sol composite abrasive grains with a doping mass ratio of 1.91% was obtained.

Doping mass ratio is 1.91% The composition and mass percentage of iron-doped colloidal silicon oxide composite abrasive polishing fluid are as follows:

Iron-doped silica sol composite abrasive grains 6.12 wt.%

Dispersant sodium hexametaphosphate 2 wt.%

Deionized water 91.88 wt.%

Comparative example 1

Undoped pure silica sol polishing fluid. That is, ferric chloride solution is not added dropwise during the reaction process to obtain a pure silica sol polishing solution not doped with iron.

The composition and mass percent of pure colloidal silicon oxide abrasive polishing fluid are as follows:

Silica sol composite abrasive grains not doped with iron 6.0 wt.%

Dispersant sodium hexametaphosphate 2 wt.%

Deionized water 92 wt.%

Polishing experiment

Use above-mentioned polishing liquid to carry out polishing experiment to sapphire substrate, silicon wafer under certain polishing conditions, polishing conditions are as follows:

Polishing machine: UNIPOL-1502 single-sided polishing machine

Polishing workpiece: sapphire substrate with a diameter of 50.8nm, silicon wafer with a diameter of 50.8nm

Polishing pad: Polyurethane material, produced by RODEL

Polishing pressure: 6 kg for sapphire polishing, 4 kg for silicon wafer polishing

Lower plate speed: 60rpm

Polishing time: 3 hours for sapphire polishing, 1 hour for silicon wafer polishing

After polishing, the substrate is then washed and dried, and then the surface topographical characteristics of the substrate are measured. Surface average roughness (Ra) and micro-roughness (RMS) were measured using an AmbiosXI-100 surface topography instrument with a resolution of 0.1 angstroms. The test range is 93.5 microns x 93.5 microns. The weight of the substrate was weighed with an analytical balance, and the weight difference before and after polishing was divided by the surface area of the substrate and the polishing time to obtain the polishing rate.

The polishing effects of each embodiment polishing liquid on sapphire are shown in Table 1. It can be seen that compared with the pure silicon oxide abrasive polishing liquid of Comparative Example 1, the iron-containing element-doped silica sol composite abrasive grain (embodiment 1, 2, 3 ) after polishing the sapphire substrate, the roughness (Ra) and micro-roughness (RMS) of the sapphire substrate surface were reduced, and the removal rate of the sapphire substrate surface was improved.

The polishing effects of each embodiment polishing liquid on silicon wafers are shown in Table 2. It can be seen that compared with Comparative Example 1 (pure silicon oxide abrasive polishing liquid), iron-containing element-doped silicon oxide sol composite abrasive grains (embodiment 1 , 2, 3) After polishing the silicon wafer, the surface roughness (Ra) and micro-roughness (RMS) of the silicon wafer are reduced, and the removal rate is greatly improved.

Claims (4)

1. a Compostie abrasive particles for ferro element doped silicon oxide colloidal sol, is characterized in that having following composition:

A. ferro element compound (iron(ic) chloride) 0.1-5 wt.%;

B. silica sol 99.9-95 wt.%.

2. a preparation method for ferro element doped silicon oxide colloidal sol Compostie abrasive particles, is characterized in that having following process and step:

A. by massfraction be 8.0 % water glass by Zeo-karb, when the pH value of the liquid flowed out is between 2.5-3.5 receive flow out liquid, then obtaining massfraction is 2.0-3.0% active silicic acid solution;

B. at 100 DEG C and under stirring, be 0.29% ferric chloride Solution and 750-3000 gram mass mark by 750-3000 gram mass mark be 2.0-3.0% active silicic acid solution, joining 3000 gram mass marks is in the crystal seed silica solution of 10%, drip massfraction is the sodium hydroxide solution of 0.4% simultaneously, control rate of addition, keep the liquid level of silicon oxide crystal seed mother liquor to keep substantially constant, and control pH scope is between 9.0-11.0;

C. control to drip and moisture velocity of evaporation, make the liquid level of mother liquor keep substantially constant, until mixed solution drips off, reaction turns off well heater after half an hour, stirs and cools to room temperature; Namely the Compostie abrasive particles of ferro element doped silicon oxide colloidal sol is obtained.

3. a polishing fluid composition, is characterized in that having following composition:

Ferro element doped silicon oxide colloidal sol Compostie abrasive particles 6-6.12 wt.%,

Sodium hexametaphosphate dispersant 2 wt.%,

Deionized water surplus;

The mass percentage sum of each composition is 100 wt.% above.

4. a preparation method for polishing fluid composition, is characterized in that having following process and step:

A. above-mentioned ferro element doped silicon oxide colloidal sol Compostie abrasive particles solution is by 350 object screens, removing macrobead;

B. the solution that deionized water is mixed with 5 liters is added wherein;

C. add 100 grams of sodium hexametaphosphate dispersants more wherein, stir; Obtain polishing fluid composition.