Method for removing boron impurities contained in polysilicon by injecting electron beams

Abstract

The invention relates to a method for removing boron impurities contained in polysilicon by injecting electron beams, in particular to a method for removing the boron impurities contained in the polysilicon by carrying out electron injection by utilizing the electron beams, belonging to the technical field of polysilicon purification by using a physical metallurgy technology. The method comprises the following steps of: firstly, heating silicon powder by utilizing a high-temperature heating furnace; then placing the silicon powder into an electron beam smelting furnace, and bombarding the silicon powder by using low-beam current electron beams; and finally removing a surface oxidation film of the silicon powder to obtain low-boron silicon powder by using an HF (hydrogen fluoride) acid solution. The invention has the outstanding advantages of showing the electrical effect of negative electricity by releasing electrons by adopting the electron beams, strengthening self electric microfields of silicon materials by combining with the self characteristics of the silicon materials, enabling the boron to be diffused to an interface by being driven by temperature and further enter a silicon dioxide layer and finally removing a silicon dioxide layer containing the boron through acid cleaning, thereby achieving the purpose of removing the boron impurities to meet the using requirements on solar grade silicon; in addition, the invention has the advantages of good purification effect and stability, little energy consumption, low cost, simple process, short period and higher production efficiency.

Description

technical field [0001] The invention belongs to the technical field of purifying polysilicon by physical metallurgy technology, and particularly relates to a method for removing impurity boron in polysilicon by using electron beams for electron injection. Background technique [0002] Solar-grade polysilicon material is the most important basic raw material for manufacturing solar cells. With the rise of the global low-carbon economy, the solar photovoltaic industry has ushered in a huge space for development. At present, the preparation of polysilicon materials for solar cells has formed a large-scale production worldwide, and common preparation techniques include: [0003] (1) Improved Siemens method: The Siemens method uses hydrochloric acid (or hydrogen, chlorine gas) and metallurgical grade industrial silicon as raw materials to perform hydrogen reduction from trichlorosilane. Now the relatively mature technology in foreign countries is the Siemens method, and it has a...

AI Technical Summary

Problems solved by technology

The main disadvantage of this method is that after a period of smelting, a dense silicon dioxide film is formed on the silicon surface under an oxygen atmosphere, and only a small area in direct contact with the ion beam can be effectively purified, resulting in low production efficiency and high application costs. Not conducive to industrial production

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