Method of argon gas purification

1、 Overview

Argon is used as the protective gas for the production of single crystal and polycrystalline silicon. In order to improve the quality of silicon crystal, how to select argon with higher purity is a topic for the production of silicon crystal. Through the use of this device, when the oxygen content of argon is less than 1 ppm, and the water content is less than 1 ppm, the oxygen and carbon content of monocrystalline silicon produced is less than 0.5 ppm, which improves the service life of monocrystalline silicon and can meet the requirements, winning customer satisfaction and market demand.

Since the general liquid argon is not purified after vaporization, its oxygen content is generally 2ppm~5ppm. Sometimes the argon provided by the gas supplier exceeds this range, and the customers using argon do not know its quality, so it often affects the quality of the products. With the argon purification device, regardless of the quality of the argon feed gas, as long as the argon enters the crystallization furnace after being treated by the purification device, the purity is always constant.

Generally, the oxygen content is less than 0.5 ppm, and the water content is less than 1 ppm. Such stable argon gas can guarantee the quality of crystal production.

High purity argon purification system

2、 Methods of argon purification

A direct deoxidation method. It is to use active metal to react with oxygen in argon to digest the oxygen in argon, so as to achieve the purpose of deoxidation, and absorb the water in argon through molecular sieve, so that the water content of argon is less than 1 ppm.

The second is to use getters. At a certain temperature, the getter can absorb nitrogen, hydrogen, oxygen, carbon monoxide, carbon dioxide, methane and other gases. After absorption treatment, the purity of argon can reach six nines. This protective gas is more suitable for the production of high-purity semiconductor monocrystalline silicon.

Purity of argon purified by getter:

O2≤0.2ppm

H2≤0.5ppm

N2≤1ppm

CO+CO2≤0.5ppm

CH4≤0.5ppm

Moisture ≤ 1ppm

One method has small equipment investment, and the service life of deoxidizer in the equipment is generally more than four years.

The second method has high equipment purification purity but relatively large investment, and the service life of getter is two years.

According to customer requirements, an analyzer can also be equipped to detect the purity of gas in the equipment online and at all times.

3、 Argon usage

High-purity argon is used for welding, stainless steel manufacturing and smelting, and also for chemical vapor deposition, crystal growth, thermal oxidation, epitaxy, diffusion, polysilicon, tungsten, ion implantation, current-carrying, sintering and other argon in the semiconductor manufacturing process as the protective gas for the production of single crystal and polysilicon.