An adsorption tower for preparing high-purity tungsten hexafluoride and its application method

Abstract

The invention discloses an adsorption tower for preparing high purity tungsten hexafluoride and a using method thereof.The adsorption tower is a tower body of a hierarchy structure.The tower body is divided into the upper-level tower body and the lower-level tower body through screen plates.The first-level tower body (14) is formed in the space between the bottom screen plate (15) and the middle screen plate (12).A gas inlet (1) is formed below the bottom screen plate (15).The second-level tower body (6) is formed in the space above the middle screen plate (12).The first-level tower body is filled with metal packing.The second-level tower body is provided with cooling coil (5) and filled with an alkali metal fluoride adsorbing agent.The cooling coil is provided with a refrigerant inlet (4) and a refrigerant outlet (7).The bottom end of the tower body is a sealing head (16).The top end of the tower body is a blind plate (9).A gas outlet (8) is formed in the blind plate.A heating sleeve is arranged on the outer side wall of the tower body in a matched mode.The content of HF and MoF6 in tungsten hexafluoride adsorbed by the adsorption tower is low, and tungsten hexafluoride in the alkali metal fluoride adsorbing agent can be recycled.

Description

technical field [0001] The invention relates to the field of tungsten hexafluoride preparation, in particular to an adsorption purification process and equipment. Background technique [0002] Tungsten hexafluoride (WF 6 ) is a gas used in the electronics industry. It is mainly used as a raw material for metal tungsten chemical vapor deposition (CVD) process in the electronics industry. use WF 6 WSi 2 Can be used as wiring material in large scale integration (LSI). With the improvement of the degree of precision of electronic industry products, WF as a raw material is also 6 The purity puts forward extremely high requirements. When the purity is required to reach more than 99.999%, the industrial product WF must be 6 Purification and purification are carried out to meet the needs of the semiconductor industry. [0003] Industrial WF 6 The main impurities are light components such as oxygen, nitrogen, HF and heavy components such as metal impurities, among which light...

AI Technical Summary

Problems solved by technology

[0005] When using NaF to adsorb HF, if powdered NaF is used, the gas is not easy to enter the inner layer of the adsorbent due to the easy conjunctiva on the surface, and the adsorption effect is poor.

However, NaF compressed into flakes or spheres, after absorbing HF, will increase in volume due to lattice changes, easily break and block channels.

Existing NaF adsorbents have disadvantages such as low porosity and low strength

During the regeneration and activation of the adsorbent, NaF will produce a large amount of ash; during the adsorption process, the reaction between NaF and HF will produce pulverization and agglomeration, and the ash or clots will accumulate at the bottom of the adsorption tower or at the air inlet, which will easily lead to the blockage of the adsorption tower

[0006] Patent document CN101070190A discloses a method for purifying tungsten hexafluoride gas. The tungsten hexafluoride gas in the crude product storage tank is passed into the bottom of the adsorption tower filled with porous spherical sodium fluoride or potassium fluoride fillers. Most of the hydrogen fluoride impurities are removed at 10-80°C. In this patent, the adsorption temperature of the adsorption tower fluctuates greatly, and the temperature control ability of the adsorption tower and the ability to prevent clogging are insufficient. WF 6 The liquefaction point is at 17.2°C, when the temperature is controlled at 3-10°C, WF 6 A large amount of liquefaction adsorption cannot be carried out in the adsorption tower. When the temperature is controlled at 80°C, the adsorbent will precipitate HF again, causing the HF content in the gas to exceed the standard.

[0007] Patent document CN101827788A discloses a method for purifying WF 6 Applicable new equipment and methods for gases, specifically providing for the production of high purity WF using carbonaceous materials by removing substantially all highly volatile gaseous impurities and problematic transition metal impurities 6 apparatus and method, which points out that the invention is especially suitable for use from WF 6 The gas removes chromium and molybdenum impurities, but the adsorption material will also adsorb a large amount of tungsten hexafluoride while removing molybdenum hexafluoride, and the adsorbed tungsten hexafluoride cannot be recovered, which affects the product yield

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