Method for growing thin silicon crystals

Abstract

Disclosed is a method for growing a thin-plate silicon crystal, comprising: flowing a molten silicon formed by melting a silicon raw material onto a liquid substrate, the molten silicon floating on the liquid substrate, and forming a molten silicon thin layer; then by controlling a temperature field, forming a temperature gradient in a horizontal direction of the molten silicon thin layer and the liquid substrate, and finally the molten silicon thin layer crystallizing to generate a thin-plate silicon crystal. Because the liquid substrate substance has a support action on the molten silicon / silicon crystal, it is easy to form thin-plate silicon with a smooth surface. In the method for growing a thin-plate silicon crystal of the present invention, a molten silicon thin layer may be formed without any solid die or string, and no substance destroying the crystal structure exists in the growing process, so that the crystallized particles of the generated thin-plate silicon are large, the area of the generated thin-plate silicon is large, and the yield is high; under the premise of guidance of a monocrystalline silicon sheet, thin-plate monocrystalline silicon may be produced.

Description

technical field [0001] The invention belongs to the field of solar-grade silicon manufacturing methods, and in particular relates to a method for producing large-area thin-plate silicon crystals. Background technique [0002] Silicon wafers, including monocrystalline silicon wafers and polycrystalline silicon wafers, are the basic materials for manufacturing crystalline silicon solar cells. In the current solar industry, more than 90% of the silicon wafers used in crystalline silicon solar cells are obtained by slicing single / polycrystalline silicon ingots. The slicing process (usually using multi-wire cutting technology) often causes a lot of waste of silicon materials due to cutting loss (Kerf Loss), and the loss of raw materials will be more than 40%. Therefore, it has become the development direction of the industry to directly produce silicon wafers from silicon raw materials through a certain crystallization method, or to produce thin-plate silicon crystals and form s...

AI Technical Summary

Problems solved by technology

Since there is no reliable support for band-shaped silicon during growth, the liquid silicon near the growth interface is often suspended by surface tension, so it is easy to form band silicon with an uneven surface when the growth rate or the surrounding flow field / temperature field fluctuates, making band silicon in the Difficulties in subsequent cell production and processing

In addition, the crystallization direction of the strip-shaped silicon in the above technology is consistent with the pulling direction of the strip-shaped silicon, while the crystallization cooling range of the strip-shaped silicon is limited to a small area. According to the pulling speed (ie production speed) of the strip-shaped silicon close to Due to the principle of crystallization cooling speed, the strip-shaped silicon crystal of the above technology cannot achieve high-speed production

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