A type of monocrystalline silicon ingot casting process

Abstract

The invention relates to a mono-like silicon ingot casting technology. The technology comprises the main steps that seed crystals at the bottom of a flat crucible are fragmented; border seed crystal blocks are inserted into seed crystal fragments along the periphery of the crucible; the spliced slab seed crystal fragments are placed into the crucible integrally, and descend along the border seed crystal blocks, and therefore the border seed crystal blocks press the slab seed crystal blocks; a silicon material is laid on each seed crystal block; the crucible is placed into an ingot casting furnace and vacuumized; by means of temperature control during the melting stage, the silicon materials are melted and permeate into spliced gaps, and seed crystals begin to be melted gradually from the face making contact with silicon liquid; by means of oriented heat dissipation, and silicon ingots grow on the unmelted seed crystals in an oriented mode, so that mono-like ingots are obtained. Compared with a traditional mono-like silicon ingot casting technology, the seed crystal blocks of the specific structure are used in the technology, in the ingot casting process, the gaps among the spliced faces can be controlled well, and the single-crystal area ratio is increased; moreover, due to the limiting function of the border seed crystal blocks, the seed crystal blocks are prevented from being heated and warping up, and the ingot casting quality is improved.

Description

technical field [0001] The invention relates to a quasi-single crystal silicon ingot casting process, and belongs to the field of silicon crystal manufacturing. Background technique [0002] In recent years, monocrystalline silicon and polycrystalline silicon have been widely used in photovoltaic solar cells, liquid crystal display and other fields. At present, the commonly used manufacturing method of silicon-like single crystal is the directional solidification method. In this method, cuboid seed crystals are laid on the bottom of a flat-bottomed crucible, and the seed crystals are regularly arranged to form a seed crystal layer. The silicon material is placed in a flat-bottomed crucible and laid on the seed layer. Through the temperature control in the melting stage, after the silicon material is melted, the seed crystal gradually melts from the surface in contact with the silicon liquid, and then the directional growth of the silicon ingot is realized on the unmelted se...

AI Technical Summary

Problems solved by technology

[0005] However, the inventor has found through experiments that the above-mentioned method still has defects.

Although the bevel splicing structure reduces the generation of gaps to a certain extent, due to the smooth bevel, the seed crystal splicing method may cause deformation of the seed crystal splicing due to pressure during the seed crystal splicing and silicon material filling process, thus affecting the subsequent single crystal ingot casting. quality, put forward high technical requirements for the splicing of seed crystals, and the performance of process tolerance becomes worse

At the same time, during the heating process, the tightly arranged seed crystals may warp due to thermal expansion, and the splicing gap between the seed crystals will become larger, resulting in the proliferation of subsequent crystal dislocations, or the formation of polycrystalline grain boundaries

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