Preliminary directional solidification process applied to polysilicon purification by medium smelting and cohesion

Abstract

The invention belongs to the field of polycrystalline silicone purification, and in particular relates to a medium smelting cohesion primary directional solidification process applied to purifying polycrystalline silicon. The process comprises medium smelting which comprises the steps of reacting a to-be-purified silicon block with a slag remover to remove boron impurity in the silicon, the process is characterized in that a silicon solution is placed in a primary directional solidification device under atmospheric condition after the medium smelting is finished, the metal impurity in the silicon solution is gathered at the top to remove by adopting a manner of water-cooling and pulling an ingot at the bottom. The primary directional solidification process has the advantages of being short in period, high in production efficiency, simple in process, saving in energy and low in cost.

Description

technical field [0001] The invention belongs to the field of polysilicon purification, and in particular relates to a preliminary directional solidification process applied to the purification of polysilicon by medium smelting and joining. Background technique [0002] In today's world, the energy crisis and the pressure of environmental pollution coexist, and people urgently need clean, safe and sustainable new energy. As an energy source that meets such requirements, solar energy has always been the goal pursued by people. The earliest use of solar energy is the utilization of its thermal effect, but it is difficult to fully meet the needs of modern society. Until the discovery of the semiconductor photoelectric effect and the manufacture of solar cells, people found new ways to use solar energy. Silicon is the most ideal raw material for solar cells. The impurities in it mainly include metal impurities such as Fe, Al, and Ca and non-metallic impurities such as B and P. ...

AI Technical Summary

Problems solved by technology

[0004] In the traditional metallurgical process flow, the dielectric melting process can only remove the B impurities in polysilicon, and has no effect on the removal of metal impurities, and a large amount of metal impurities will bring great pressure to the subsequent directional solidification process, so the directional The solidification process often needs to be repeated 1 or 2 times, resulting in a large expenditure cost