Continuous producing technique for ultra-high pure nitric acid

Abstract

The invention relates to a process for continuously producing extra high purity nitric acid, which comprises the following steps: first, industrial grade 80-90% nitric acid raw material and double allyl 18-crown-6 ether organosilicon macromolecular complexing agent accounting for 0.2-2% of the weight of nitric acid raw material are mixed in a pretreater, then, the mixture is filtered by a micro-filtration membrane under a working pressure of 0.1-0.2 Mpa, the filtrate enters a rectification tower, and the semi-finished product going through the rectification tower is diluted by ultra pure water in a dilution device; after the dilution is finished, the dissociative NO2 is expelled by high pure nitrogen in a whitening device, and the obtained finished product is filtered by a nanometer filter membrane and enters a finished product receiver under the working pressure of 0.5-0.8 Mpa; wherein, the aperture of the micro filtration membrane is 0.2 to 0.8 Mu m, and the aperture of the nanometer filter membrane is 0.5 to 1.5 nm. In the prepared ultra high purity nitric acid, the content of single cation is lower than 1 ppb, the content of single anion is lower than 100 ppb, and the content of the dust particle larger than 0.5 Mu m is lower than 5 per milliliter. The production process for extra high purity nitric acid has the advantages of simple technique, low production costs, high purity of products, low content of impurity ions, and applicability for large-scale mass production.

Description

technical field [0001] The invention relates to an ultra-clean and high-purity chemical reagent, in particular to a process for continuous production of ultra-high-purity nitric acid. Ultra-high-purity nitric acid is mainly used in the microelectronics industry to manufacture large-scale integrated circuit semiconductor devices for cleaning and corrosion. Background technique [0002] Ultra-clean and high-purity chemical reagents, also known as microelectronic chemicals, are one of the indispensable key basic chemical materials in the microfabrication process of electronic technology. They are mainly used for chip cleaning and corrosion. Yield, electrical performance and reliability have a very significant impact. As the storage content of the chip (IC) continues to increase, the capacity is also increasing, so the oxide film on the chip surface becomes thinner. However, alkali metal impurities in microelectronic chemicals, such as sodium (Na), calcium (Ca) and other impur...

AI Technical Summary

Problems solved by technology

Nitric acid with a concentration of more than 95% has high volatility and stability. Most of the impurities contained in it are nitrates with a high boiling point. They can be separated in the tower kettle during the rectification process, but some of them are volatilized with nitric acid. Impurities with similar degrees are difficult to remove

Therefore, after general industrial nitric acid is rectified, its impurity content still cannot reach the standard of ultra-pure nitric acid

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