Electronic grade phosphorane purification system and processing method

Abstract

The invention discloses an electronic grade phosphorane purification system. The electronic grade phosphorane purification system comprises an absorbing tower, a compressor, an adsorption system, a light removal rectifying tower, and a heavy removal rectifying tower. The invention also discloses an electronic grade phosphorane processing method. The method comprises the following steps: a phosphorane raw material is introduced in the tower from bottom of the absorbing tower, realizes counter-current contacting with absorption liquid from down to up, and the whole hydrogen sulfide and carbon dioxide accounting for 10-40% of that of total amount are absorbed; gas at the top of the absorbing tower is compressed through a compressor and is introduced to the adsorption system, and passes through an adsorbent layer for absorbed dehydration from up to down; the gas through the absorbed dehydration is introduced to the light removal rectifying tower for rectification, a light component is discharged from the top of the light removal rectifying tower to a condenser at the top of the light removal rectifying tower, a heavy component is introduced to the heavy removal rectifying tower for rectification, the light component is discharged from the top of the tower and is discharged to the condenser at top of the heavy removal rectifying tower, and noncondensable gas at the top of the condenser is a phosphorane finished product. The phosphorane purification system takes amine liquid as absorption liquid, and the purity of the obtained phosphorane is greatly increased, which can achieve 7N.

Description

technical field [0001] The invention relates to a purification system for electronic grade phosphine and a treatment method for phosphine based on the purification system. Background technique [0002] Phosphine (PH 3 ) and arsine (AsH 3 ) are similar in physical properties, both are important N-type doping sources in semiconductor manufacturing, and are also used in ion implantation processes, epitaxial GaP materials, polysilicon chemical vapor deposition, etc., and are extremely important electronic special gases. In addition, they are also widely used in solar cells, food fumigation and other fields. [0003] The synthesis methods of phosphine mainly include chemical method, electrolysis method and microwave method, but no matter which kind of synthesis process will produce unnecessary impurities. At present, the purity of domestically synthesized phosphine after pretreatment is 98-99%, and the impurities contained in it are for N 2 , O 2 , CO, CH 4 , CO 2 、SiH 4 ...

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Problems solved by technology

[0005] The purpose of the present invention is in order to solve that above-mentioned prior art does not go out hydrogen sulfide and carbon dioxide influence follow-up phosphine purity, and organic amines such as MDEA are to H in the process of going out acid gas. 2 S and CO 2 There is a problem of selective absorption, and an electronic grade phosphine purification system integrating absorption, desorption, condensation, compression, adsorption and rectification is provided, based on the fact that the azeotropic temperature of hydrogen sulfide and impurities is close to the product phosphine, while carbon dioxide Based on the principle of low boiling point of difficult-to-separate ethane, all hydrogen sulfide and part of carbon dioxide are selectively absorbed by controlling the number of theoretical plates, and then the unabsorbed carbon dioxide and ethane are azeotropically removed from the top of the rectification tower through rectification. The purification system further purifies the phosphine with a purity of 98%wt to obtain phosphine with the content of all impurities ≤ 100ppb, which not only increases the yield from the existing 85% to over 95%, but also increases the purity from 6N to 7N, thus reducing downstream processing load

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