阅读说明：本技术 一种二氧化硅胶体及其制备方法 (Silica colloid and preparation method thereof ) 是由 孔慧 刘卫丽 宋志棠 李宏亮 于 2019-10-23 设计创作，主要内容包括：本发明提供一种二氧化硅胶体及其制备方法,所述二氧化硅胶体的制备方法包括如下步骤：将无机碱溶液按一定滴加速度要求加入到pH为2～4的活性硅酸中制得pH为8.5～9.5的碱性混合物；将碱性混合物升温至90℃～100℃保温至少10min获得非球形二氧化硅晶种；将非球形二氧化硅晶种加热至沸,在保证体系pH为9.0～10.0的情况下,滴加活性硅酸保温至少10min；自然冷却至室温获得二氧化硅胶体,且二氧化硅胶体中的二氧化硅颗粒为非球形。这种新的制备方法简单有效,能够确保二氧化硅胶体中的二氧化硅颗粒为非球形,并且避免了二氧化硅胶体中如Ca<Sup>2+</Sup>、Mg<Sup>2+</Sup>、Al<Sup>3+</Sup>等金属阳离子杂质,拓宽了其应用范围。(The invention provides a silicon dioxide colloid and a preparation method thereof, wherein the preparation method of the silicon dioxide colloid comprises the following steps: adding an inorganic alkali solution into active silicic acid with the pH of 2-4 according to a certain dropping speed requirement to prepare an alkaline mixture with the pH of 8.5-9.5; heating the alkaline mixture to 90-100 ℃, and preserving the temperature for at least 10min to obtain non-spherical silicon dioxide crystal seeds; heating the non-spherical silicon dioxide seed crystal to boil, and dripping active silicic acid and preserving heat for at least 10min under the condition of ensuring that the pH of the system is 9.0-10.0; naturally cooling to room temperature to obtain the silica colloid, wherein the silica particles in the silica colloid are non-spherical. The new preparation method is simple and effective, can ensure that the silica particles in the silica colloid are non-spherical, and avoids Ca in the silica colloid 2+ 、Mg 2+ 、Al 3+ And metal cation impurities are added, so that the application range of the catalyst is widened.)

1. The preparation method of the silica colloid is characterized by comprising the following steps:

adding an inorganic alkali solution into active silicic acid with the pH of 2-4 to prepare an alkaline mixture with the pH of 8.5-9.5;

heating the alkaline mixture to 90-100 ℃, and preserving the temperature for at least 10min to obtain a non-spherical silicon dioxide seed crystal solution;

heating the non-spherical silicon dioxide seed crystal to boil, and dripping active silicic acid and preserving heat for at least 10min under the condition of ensuring that the pH of the system is 9.0-10.0;

naturally cooling to room temperature to obtain the non-spherical silica colloid.

2. The preparation method according to claim 1, wherein the active silicic acid is obtained by adding a water glass solution into a strong acid type cation exchange resin for cation exchange.

3. The method according to claim 2, wherein the silica content in the water glass solution is 3 to 6 wt%.

4. The method according to claim 1, wherein the inorganic base is one or two selected from potassium hydroxide and sodium hydroxide.

5. The method according to claim 1, wherein the concentration of the inorganic alkali solution is 0.5 to 2.0 wt%.

6. The method according to claim 1, wherein the volume ratio of the nonspherical silica seed crystal to the dropwise added active silicic acid is 0.1 to 0.15.

7. The production method according to claim 1, wherein the speed of dropping the active silicic acid is 7 to 10 ml/min.

8. The method according to claim 1, wherein the alkali mixture is obtained by adding an inorganic alkali solution to the activated silicic acid at a rate of 1.0 to 5.0 ml/min.

9. A non-spherical silica colloid obtained by the production method according to any one of claims 1 to 8.

10. Use of the non-spherical silica colloid according to claim 9 as a polishing liquid in integrated circuits.

Technical Field

The invention relates to a silicon dioxide colloid, in particular to a silicon dioxide colloid used in polishing solution.

Background

With the high development of integrated circuit technology, the surface quality of the substrate material used is more and more demanding. As the size of devices decreases, the depth of focus of optical lithography equipment decreases, requiring flatness of the wafer surface with acceptable resolution on the order of nanometers. To solve this problem, a Chemical Mechanical Polishing (CMP) technique capable of global planarization is one of the important key processes in semiconductor manufacturing. Chemical mechanical polishing utilizes chemical reaction and mechanical polishing to achieve the purpose of planarization, so that the polishing solution plays a central role in the CMP process. As one of the important components of CMP slurry, abrasive particles affect the removal of surface material of a wafer during a CMP process through their hardness, surface chemical activity, surface charging, and the like. Currently, the abrasive particles that are the mainstream in the market are nanoscale silicas, either sintered or amorphous. The sintered silicon dioxide has edges and corners, has higher hardness, has higher removal rate in the polishing process, but is easy to scratch the surface of a wafer; amorphous silica is generally spherical, smooth in edge, less hard, and less damaging to the wafer surface during polishing, but has a problem of low polishing rate (spherical particles are easily rolled during polishing). How to increase the polishing rate of the material without damaging the surface quality is a big problem faced by the CMP polishing solution. The non-spherical silica particles with unique shape, large specific surface and soft texture can simultaneously realize the perfect combination of rapid polishing and high surface quality, are favored by researchers and are prepared by various preparation methods. The preparation methods are roughly divided into two types, one is prepared by using an organic base catalyst to influence the isotropic growth of particles in the preparation process, and for example, the methods are adopted in patents of US6334880B1, US2008/0038996A1 US2009/0223136A1 and US2010/0163786A, CN 1102390837A; another class oneUsually by "cation induction" (e.g. Ca)²⁺、Mg²⁺、Al³⁺) Namely, the method is adopted to prepare by selecting proper divalent or trivalent cations as the morphology control agent, such as patents CN103408027A, CN101402829A, CN101626979A and the like. The organic base is not environment-friendly and is not suitable for large-scale production; the introduction of divalent or trivalent cations can reduce the purity and stability of colloidal silicon dioxide, limiting its use in integrated circuit polishing processes.

Disclosure of Invention

In view of the above-mentioned disadvantages of the prior art, an object of the present invention is to provide a silica colloid and a method for preparing the same, which solve the problems of the prior art.

To achieve the above objects and other related objects, the present invention is achieved by the following technical solutions.

The invention firstly provides a preparation method of silicon dioxide colloid, which comprises the following steps:

adding an inorganic alkali solution into active silicic acid with the pH of 2-4 to prepare an alkaline mixture with the pH of 8.5-9.5;

heating the alkaline mixture to 90-100 ℃, and preserving the temperature for at least 10min to obtain a non-spherical silicon dioxide seed crystal solution;

heating the non-spherical silicon dioxide seed crystal to boil, dripping active silicic acid under the condition of ensuring that the pH of the system is 9.0-10.0, and preserving the temperature for at least 10 min;

naturally cooling to room temperature to obtain the non-spherical silica colloid.

The heat preservation time in the application can be determined according to the reaction condition, and under the general condition, the heat preservation time is not more than 1 h.

According to the technical scheme of the invention, the active silicic acid is obtained by adding a water glass solution into a strong acid type cation exchange resin for cation exchange.

The active silicic acid in this application is a colloidal solution with a silica content of 2.0 wt% to 6.0 wt%, and the most important reason for the ability of silicic acid to nucleate growth into nanoparticles is due to its polymeric nature. The silicic acid molecules can be partially or totally polymerized into a chain or three-dimensional network structure, and the polymerization degree is generally different from dozens to hundreds.

According to the technical scheme of the invention, the content of silicon dioxide in the water glass solution is 3 wt% -6 wt%.

According to the technical scheme of the invention, the inorganic base is one or two selected from potassium hydroxide and sodium hydroxide.

According to the technical scheme of the invention, the concentration of the inorganic alkali solution is 0.5-2.0 wt%. The inorganic base solution in this application is an aqueous solution of an inorganic base.

According to the technical scheme of the invention, the volume ratio of the non-spherical silicon dioxide seed crystal to the dropwise added active silicic acid is 0.1-0.15.

According to the technical scheme of the invention, the speed of dripping the active silicic acid is 7-10 ml/min. In order to ensure that the silicon dioxide particles in the finally obtained silicon dioxide colloid are non-spherical, the speed of dripping the active silicic acid cannot be too fast or too slow, and the particles can only be ensured to grow according to the shape of the non-spherical silicon dioxide seed crystal at a proper speed, and if the dripping speed is too fast, new round seed crystals are easy to form nuclei independently among the silicic acid; if the dropping speed is too slow, the production efficiency is affected.

According to the technical scheme of the invention, the inorganic alkali solution is added into the active silicic acid at the speed of 1.0-5.0ml/min to obtain the alkaline mixture. In order to ensure that the formed silicon dioxide seed crystal is non-spherical, the speed of adding the inorganic alkali solution into the active silicic acid is moderate, and spherical particles are easily generated at an excessively high adding speed; too slow an addition rate can result in instability of the silicic acid, which tends to gel and fail to form silica seeds.

The invention also discloses the non-spherical silicon dioxide colloid prepared by the preparation method.

According to the non-spherical silica colloid, the axial particle size of silica particles in the non-spherical silica colloid is 10-20nm, and the radial particle size is 40-80 nm.

The nonspherical silica colloid has a solid content of 20 to 30 wt%.

The application also discloses the use of the non-spherical silica colloid as described above as a polishing solution in integrated circuits.

The use of the above-mentioned, adjust the pH of said non-spherical silica colloid to 9.5-10.5 and use as polishing solution.

The present application provides a novel silica gel and a method for preparing the same, which is simple and effective, can ensure that silica particles in the silica gel are non-spherical, and can prevent Ca in the silica gel from being present^{2 +}、Mg²⁺、Al³⁺Metal cation impurities are waited, so that the application range of the metal cation impurities is widened, and the metal cation impurities are very suitable for being applied to the fields of integrated circuits and the like; in addition, organic alkali is not adopted in the method, so that the environmental protection problem caused in production can be effectively avoided.

Drawings

FIG. 1 shows an electron microscope picture of non-spherical silica particles prepared in example 1 of the present invention.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

Before the present embodiments are further described, it is to be understood that the scope of the invention is not limited to the particular embodiments described below; it is also to be understood that the terminology used in the examples is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. Test methods in which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under conditions recommended by the respective manufacturers.

When numerical ranges are given in the examples, it is understood that both endpoints of each of the numerical ranges and any value therebetween can be selected unless the invention otherwise indicated. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In addition to the specific methods, devices, and materials used in the examples, any methods, devices, and materials similar or equivalent to those described in the examples may be used in the practice of the invention in addition to the specific methods, devices, and materials used in the examples, in keeping with the knowledge of one skilled in the art and with the description of the invention.