Seed crystal splicing structure for ingot casting

Abstract

The invention relates to a seed crystal splicing structure for ingot casting. The structure comprises mutually spliced seed crystal blocks, a splicing surface between adjacent seed crystal blocks is a plane vertical to the bottom of a crucible, the seed crystal blocks at one side of the splicing surface are provided with an elongated rectangular slot, the seed crystal blocks at the other side of the splicing surface are provided with an elongated rectangular projection suitable for being insert to the rectangular slot, and after the adjacent seed crystal blocks are spliced, the rectangular projection is insert to the rectangular slot, and a gap between splicing surfaces is lower than 0.5mm. The splicing surface of the seed crystal blocks are provided with the rectangular projection and the rectangular slot cooperating with each other to form a mortise and tenon joint structure to improve the lamination degree of the seed crystal splicing surface, and seed crystals at edges are expanded in the heating process, so the mortise and tenon joint structure is compact, the gap is small, the lamination of the adjacent seed crystal blocks is close, and the enlargement of the gap induced by cocking of edges of the seed crystal blocks is prevented, thereby the crystal dislocation defect is maximally reduced, and the monocrystalline area proportion is improved.

Description

technical field [0001] The invention relates to a seed crystal splicing structure for casting ingots, and belongs to the field of silicon crystal manufacturing. Background technique [0002] In recent years, silicon single crystal and silicon polycrystalline have been widely used in photovoltaic solar cells, liquid crystal display and other fields. At present, the common manufacturing method of silicon-like single crystal is the directional solidification method. In this method, cuboid seed crystals are laid on the bottom of the flat-bottomed crucible, and the seed crystals are arranged regularly to form a seed crystal layer. The silicon material is placed in a flat-bottomed crucible and laid on the seed crystal 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 ...

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Problems solved by technology

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

Although the bevel splicing 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 filling process, thus affecting the quality of the subsequent single crystal ingot. , the splicing of the seed crystal puts forward very high technical requirements, and the process tolerance performance 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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