Preparation method of silicon ingot with large-size column crystals

Abstract

The invention discloses a preparation method of a silicon ingot with large-size columnar crystals and relates to a preparation method of a columnar crystal silicon ingot. The preparation method aims at solving the problem of relatively small width of the column crystals of the silicon ingot prepared by virtue of the existing electromagnetic continuous casting technology which affects the improvement on the photoelectric conversion efficiency and providing a directional growth method of the silicon ingot with large-size grains. The preparation method comprises the following steps: firstly, filling a hopper with silicon particles; secondly, vacuumizing a vacuum chamber by virtue of a vacuum pump; thirdly, introducing 300-400Pa argon into the vacuum chamber; fourthly, electrifying an induction coil with single-phase alternating current; fifthly, starting a stepper motor; sixthly, staring a displacement motor pull rod; and seventhly, processing the columnar crystal silicon ingot to remove a polycrystalline layer to obtain the polycrystalline silicone ingot with a directional solidification, wherein the thickness of the polycrystalline layer outside the columnar crystal silicon ingot is 1mm-2mm and columnar crystal parallel to the direction of a pull rod is formed in the outer layer of the columnar crystal silicon ingot. The preparation method is applied to the field of green energy manufacturing.

Description

technical field [0001] The invention relates to a preparation method of a columnar crystal silicon ingot. Background technique [0002] The authorized patent name is a preparation method of polysilicon ingot with directional solidification structure (patent number: ZL201010609932.8), which solves the problem that the existing electromagnetic continuous casting cannot directional solidify polysilicon, or the pollution of ceramic or graphite containers is reduced during directional solidification of polysilicon. The problem of polysilicon purity. Using a method for preparing polycrystalline silicon ingots with a directional solidification structure, the prepared silicon ingots are all columnar crystals with a directional solidification structure parallel to the pulling direction except that the surface layer is a polycrystalline area of ​​about 1-2 mm. The width of the columnar crystals is It is about 1-2.8mm, but there is still a lot of room for improvement in the width of c...

AI Technical Summary

Problems solved by technology

At present, the preparation of directionally solidified polycrystalline silicon ingots is mainly carried out in ceramic (corundum) or graphite sleeves. The inner wall of the sleeves will pollute the granular silicon, which will eventually affect the purity of the silicon ingots.

Electromagnetic continuous casting technology is a technology that can directionally solidify polysilicon, but the width of its columnar crystals is mostly less than 3mm. Although the grain boundaries are greatly reduced, it is still difficult to reach the width of columnar crystals prepared in ceramic crucibles.

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