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Method of preparing alkali resistance ultra-pure silicasol

A silica sol, alkali-resistant technology, applied in the field of preparation of alkali-resistant ultra-high-purity silica sol, can solve the problems of low polishing speed, difficult to use, poor alkali resistance, etc., achieve high polishing speed, save production costs, cost reduction effect

Active Publication Date: 2007-08-08
苏州西丽卡电子材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] (1) Many materials such as silicon wafers, TEOS films used as insulating materials (ILD) in chips, etc. often need to be polished under strong alkaline conditions to obtain good results. Under alkaline conditions, the STOBER method The polishing speed of silica sol is often lower than that of silica sol produced by the water glass method. The biggest reason is that the silica sol produced by this method has poor alkali resistance compared with the silica sol produced from water glass. That is to say, at the same Under high pH conditions, the silica sol of the STOBER method is more easily dissolved by alkali
Therefore, it is difficult to use under strong alkaline conditions of PH>10
[0006] (2) The electronic-grade organosilane used as raw material is relatively expensive, and the reaction requires a large amount of electronic-grade methanol or ethanol as a solvent, so the cost is high

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026]Example 1: 20 g of distilled and purified tetramethoxysilane (TMOS) was dissolved in 100 g of 1.4% KOH aqueous solution, stirred and heated to a transparent colorless liquid (solution A).

[0027] In another container, 80 grams of tetramethoxysilane (TMOS) was dissolved in 400 grams of 0.1% sulfuric acid solution, and stirred until a colorless and transparent solution (solution B).

[0028] Heat solution A to boiling, add solution B dropwise to solution A at an even speed for 40 minutes, after completion, stir for 15 minutes, heat and distill off by-product methanol and part of water to obtain silica sol, concentration 20%, PH = 9.5. Tested by the principle of dynamic light scattering, the average particle size is 70nm.

[0029] The silica sol is tested by ICP mass spectrometry after being treated with HF-HNO3 acid, and the following impurity content is obtained:

[0030] Al Ca Fe K Mg Na Zn

[0031] <100ppb <100ppb <100ppb 5750ppm <100ppb <100ppb <100ppb

[0032] Ot...

Embodiment 2

[0033] Example 2: 200 grams of 2.2% KOH (weight concentration) aqueous solution was placed in a container (solution A).

[0034] In another container, 200 grams of tetramethoxysilane (TMOS) was dissolved in 500 grams of 0.2% sulfuric acid solution, and stirred until a colorless and transparent solution (solution B).

[0035] Heat solution A to boiling, add solution B dropwise to solution A at an even speed for 100 minutes, after completion, stir for 15 minutes, heat and distill out by-product methanol and a part of water.

[0036] The obtained silica sol has a concentration of 20% and a pH of 9.5. Tested by the principle of dynamic light scattering, the average particle size is 72nm.

[0037] The silica sol is tested by ICP mass spectrometry to obtain the following impurity content:

[0038] Al Ca Fe K Mg Na Zn

[0039] <100ppb <100ppb <100ppb 8840ppm <100ppb <100ppb <100ppb

[0040] Other metallic impurities were not detected. The above results show that the silica sol h...

Embodiment 3

[0041] Embodiment three: the ammoniacal liquor of 20 gram 28% is mixed with the water of 100 gram (solution A), in another container 80 gram tetramethoxysilane (TMOS) is dissolved in the sulfuric acid solution of 400 gram 0.1% (solution A) B).

[0042] Heat solution A to boiling, add solution B dropwise to solution A at a constant speed for 40 minutes, after completion, stir for 15 minutes, heat to evaporate by-product methanol and part of water, and add a certain amount of ammonia water dropwise in order to maintain the pH value.

[0043] The obtained silica sol has a concentration of 20% and a pH of 9.

[0044] Tested by the principle of dynamic light scattering, the average particle size is 65nm. Test by ICP mass spectrometry, obtain following impurity content:

[0045] Al Ca Fe K Mg Na Zn

[0046] <100ppb <100ppb <100ppb <100ppb <100ppb <100ppb <100ppb

[0047] Other metallic impurities were not detected.

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PUM

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Abstract

The invention discloses a making method of alkaline-resistance hyperhigh pure silicasol, which comprises the following steps: 1. adopting distilled pure organic silicane as raw material; dissolving in the inorganic acid or organic acid to obtain acid metasilicate acid solution; 2. dissolving rectified organic silicane in the inorganic alkaline or organic alkaline solution to obtain the alkaline silicon solution; or diluting inorganic alkaline or organic alkaline solution to obtain alkaline solution without silicon; 3. reacting acid metasilicate acid solution and alkaline solution without silicon under 105 deg.c; obtaining the silicasol; 4. heating silicasol under normal pressure or decompressing condition to boil to remove carbinol or alcohol and partial water; obtaining the product with density over 20%.

Description

technical field [0001] The invention relates to a preparation method of alkali-resistant ultra-high-purity silica sol. Background technique [0002] Silica sol is a suspension dispersion of silicon dioxide particles in water. Ultra-high-purity silica sol is mainly used in precision polishing of semiconductor materials, such as silicon wafers and germanium wafers, as well as in the chemical process of multi-layer wiring of integrated circuits. In the mechanical planarization (CMP) process, as well as in the precision polishing of hard disk aluminum substrates, it is the main component in the semiconductor material polishing fluid, and is an indispensable and important consumable in the modern microelectronics industry. Ultra-high-purity silica sol is the highest-grade product among silica sols. Its most important feature is that the content of metal impurities is extremely low, generally at 10PPM or even 1PPM, or less than one part per million, which is far lower than that of...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/14
CPCC01B33/141
Inventor 王宇湖张宁
Owner 苏州西丽卡电子材料有限公司
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