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Method for preparing silica sol with large particle size and narrow distribution

A narrow distribution, silica sol technology, applied in chemical instruments and methods, silicon compounds, inorganic chemistry, etc., can solve problems such as difficulty in meeting CMP requirements, small particle size, and wide particle size distribution

Active Publication Date: 2022-03-29
AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] There have been many patent reports on the preparation of silica sol by ion exchange method, but most of them have shortcomings such as too small particle size and wide particle size distribution
For example, the particle size of silica sol prepared by CN 106006651 A is too small; CN 1155514 A discloses a method for preparing narrowly distributed silica sol, but the method adopts a microporous ultrafiltration membrane screening process to remove small colloidal particles below 20nm, The cost is higher; CN102838124 A adopts calcium silicate as raw material to prepare silica sol, but there is a problem of calcium sulfate waste residue treatment, and calcium sulfate is slightly soluble in water (18 ℃ solubility 0.255g / 100g), resulting in excessive calcium ion concentration in the product, Difficulty meeting CMP requirements

Method used

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  • Method for preparing silica sol with large particle size and narrow distribution
  • Method for preparing silica sol with large particle size and narrow distribution

Examples

Experimental program
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Effect test

Embodiment 1

[0033] Preparation of silicic acid: Weigh 100 g of anhydrous sodium silicate, stir and dissolve in 900 g of water to obtain a sodium silicate solution. The solution was successively passed through a cation exchange column and an anion exchange column (flow rate 10mL / min), and the part with pH2 Content 4.12%. Take 12.14mL of the above silicic acid, add water and dilute to SiO 2 The content is about 0.01%, and the silicic acid solution A is obtained; another fresh silicic acid solution is taken and diluted with water to SiO 2 content of 7.5%, to obtain silicic acid solution B.

[0034] Silicic acid aging: add 2.5g of ammonium acetate crystals to silica gel solution A, adjust the pH to 6-7, and keep it at 40°C for 6h, the viscosity reaches 10mPa·s, and then pass through a 0.2μm microporous membrane to obtain aged silicon Acid solution A (SiO 2 content of about 0.05%).

[0035] Seed crystal preparation: Add 1g of sodium hydroxide solution (1.0mol / L) to 1kg of aged silicic acid...

Embodiment 2

[0039] Preparation of silicic acid: Weigh 60 g of anhydrous sodium silicate, stir and dissolve in 940 g of water to obtain a sodium silicate solution. The solution was successively passed through a cation exchange column and an anion exchange column (flow rate 10mL / min), and the part with pH2 Content 2.39%. Take 105mL of the above silicic acid, add water and dilute to SiO 2 The content is about 0.1%, to obtain silicic acid solution A; take another fresh silicic acid, add water and dilute to SiO 2 content of 0.5%, to obtain silicic acid solution B.

[0040] Aging of silicic acid: Add 5g of ammonium acetate crystals to silica gel solution A, adjust the pH to 6-7, and keep it at 30°C for 24 hours, the viscosity reaches 15mPa·s, and then pass through a 0.2μm microporous membrane to obtain aged silicic acid Solution A (SiO 2 content of about 0.25%).

[0041] Seed crystal preparation: add 1g of sodium hydroxide solution (0.1mol / L) to 1kg of aged silicic acid solution A, and heat...

Embodiment 3

[0045] Preparation of silicic acid: Weigh 120 g of anhydrous sodium silicate, stir and dissolve in 880 g of water to obtain a sodium silicate solution. The solution was successively passed through a cation exchange column and an anion exchange column (flow rate 10mL / min), and the part with pH2 Content 5.24%. Take 191mL of the above silicic acid, dilute with water to SiO 2 The content is about 1% to obtain silicic acid solution A; take another fresh silicic acid and dilute it with water to SiO 2 content of 10%, to obtain silicic acid solution B.

[0046] Aging of silicic acid: Add 5g of ammonium acetate crystals to silica gel solution A, adjust the pH to 6-7, and keep it at 60°C for 1 hour, until the viscosity reaches 5mPa·s, and then pass through a 0.2μm microporous membrane to obtain aged silicic acid Solution A (SiO 2 content of about 1%).

[0047] Seed crystal preparation: add 2g sodium hydroxide solution (0.5mol / L) to 1kg aged silicic acid solution A, and heat to boili...

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Abstract

The invention provides a method for preparing silica sol with large particle size and narrow distribution. The method comprises the following steps: preparing two silicic acid solutions with different concentrations, aging one silicic acid solution to improve the reaction activity of silicic acid to obtain an aged silicic acid solution, obtaining a seed crystal solution by using the aged silicic acid solution, and preparing the silica sol by using the seed crystal solution and the other silicic acid solution. The silica sol is larger in particle size and narrower in distribution.

Description

technical field [0001] The invention relates to a method for preparing silica sol with large particle size and narrow distribution suitable for silicon chip CMP by using silicate as raw material and adopting an improved ion exchange method. Background technique [0002] Silicon wafers are key materials in the IC industry. Before they are processed, silicon wafers need to be polished at a high level to meet the requirements of high-resolution lithography for surface flatness. The chemical mechanical polishing (CMP) process is currently recognized as the best global planarization process technology for silicon wafers in the IC process, and silica sol is the only available abrasive in the CMP polishing fluid for silicon wafers. Silicon wafer CMP has higher requirements on the particle size and distribution of silica sol. Large particle size silica sol has high polishing rate and short polishing time. [0003] The preparation methods of silica sol for CMP mainly include ion ex...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/141
CPCC01B33/141C01P2004/04
Inventor 高逸飞李洪深吕毅张剑
Owner AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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