Technology for recycling high-purity cut silicon powder by dry method

Abstract

The invention provides a technology for recycling high-purity cut silicon powder by a dry method. A semiconductor device (comprising an integrated circuit and a solar battery) mostly is processed by cutting a silicon ingot (stick) into sheets; and the cut silicon powder can be recycled only if various blended foreign substances and impurities, particularly harmful iron impurities are eliminated. The conventional method for recycling the high-purity cut silicon powder by acid pickling and flotation comprises the steps of: performing chemical reaction on the foreign substances and the impurities, and selectively sorting the silicon powder according to the difference between the surface tension and the adhesive force of the substances. The steps of the conventional method are performed in the liquid medium, so new impurities are introduced certainly and environment is polluted; and the process period is long, the energy consumption is high and the recycling cost is high. The technology comprises the steps of: separating the cut silicon powder, and the foreign substances and the impurities into monomer particles which are suspended on a bidimensional plane and in a three-dimensional space by using airflows, namely turbulent flows with specified performance, and sorting the suspended particles in an electrostatic field, a magnetostatic field, an electromagnetic field and a centrifugal force field. The environmental pollution is reduced, the energy is saved, the efficiency is improved and the cost is reduced.

Description

1 Technical field: [0001] The invention belongs to physics and semiconductor materials. 2 background technology: [0002] Existing semiconductor devices (including integrated circuits and solar cells) are mostly processed by cutting silicon ingots (rods) into sheets, and the recovery of cut silicon powder requires the removal of various foreign impurities, especially harmful iron impurities. To ensure the physical properties of the silicon wafer material. [0003] In the past, the method of pickling was used to chemically react foreign matter impurities with acid, and the solid material was changed into a soluble liquid for separation; recently, some people used the flotation method, using the difference in surface tension and adhesion of the material to selectively separate the silicon Powder sorting. They are all carried out in a liquid medium, which will inevitably introduce new impurities and pollute the environment. The process cycle is long, the energy consumption is...

AI Technical Summary

Problems solved by technology

They are all carried out in liquid medium, which will inevitably introduce new impurities and pollute the environment. The process cycle is long, the energy consumption is large, and the recovery cost is high.

Images