Fine preparation process for high-purity nitrogen trifluoride gas

Abstract

The present invention relates to a method for refining high-purity NF gas by using crude product NF3 gas as raw material gas produced by electrolysis using NF4F-xHF as electrolyte system, and said method includes the following steps: A. removing impurities of H2O and HF from raw material gas in HF-removing tower; B. removing NxFy and FxOy from raw material gas in high-temp. cracking tower; C. removing N2O impurity from raw material gas in oxidation tower; D. removing oxidation substances produced in above-mentioned high-temp. cracking and oxidation steps of B and C in reduction tower; E. removing acidic substances from raw material gas in alkali-washing tower; F. removing water from raw material gas in low-temp. dewatering tower; G rectifying in rectifying tower.

Description

(1) Technical field [0001] The invention relates to a process for preparing high-purity nitrogen trifluoride gas, which is suitable for using NH 4 F-xHF (or add a small amount of KF) is the crude NF produced by electrolysis of the electrolyte system 3 The gas is the raw material gas, which is further refined and purified to obtain high-purity NF 3 gas. Through the method of the present invention, the crude product NF with a purity of more than 97% can be 3 The gas is purified to more than 99.99%, this high-purity NF 3 The gas can be directly used in the microelectronics manufacturing industry as an etchant and cleaning agent in high-density integrated circuits. (two), background technology [0002] NF 3 Gases are widely used in fields such as high-energy lasers, semiconductor technology, and chemical vapor deposition, and have good application prospects. But as an electron gas, it is NF 3 The purity of the gas has higher requirements. Generally, its purity should not ...

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Problems solved by technology

[0006] due to CF 4 Boiling point of gas and NF 3 The boiling points of the gases only differ by 1°C, and their other physical and chemical properties are also very similar. 3 CF in gas 4 Gas impurities are very difficult, which will inevitably increase the production of high-purity NF 3 Difficulty and production cost of gas

Especially when raw material NF 3 CF in gas 4 When the content of gas impurities is high (higher than 500ppm), the preparation of high-purity NF 3 Gas equipment processing, process realization difficulty and refining cost are very high, the produced high-purity NF 3 Gases are also less profitable, not conducive to high-purity NF 3 Industrial production of gases

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