Seed crystal splicing structure suitable for directional solidification ingot casting

Abstract

The invention relates to a seed crystal splicing structure suitable for directional solidification ingot casting. The seed crystal splicing structure comprises seed crystal blocks which are spliced mutually, wherein L-shaped and inverted L-shaped structures are respectively arranged at splicing parts of the adjacent seed crystal blocks so that splicing surfaces are in the shape of mutually fastening steps, the adjacent seed crystal blocks are provided with two pairs of matched cylindrical holes at fastening parts, the cylindrical holes are perpendicular to the bottom of a crucible, after the seed crystal blocks are spliced, the paired cylindrical holes are spliced face to face to form cylindrical cavities, cylindrical silicon rods are inserted into the cylindrical cavities, and gaps between the cylindrical silicon rods and the cylindrical holes are less than 0.5mm. By inserting the silicon rods into the cylindrical holes, the stability of seed crystal block splicing can be improved, and the fitting degree of the seed crystal splicing surfaces can also be increased; and seed crystals on the edges expand by heat in a heating process, therefore, tenon and mortise structures are relatively tight, the gaps become small, and the adjacent seed crystal blocks are more tightly fitted to prevent the enlargement of the gaps caused by upwarp of the edges of the seed crystal blocks, thus reducing the defect of crystal dislocation to the greatest extent and improving the performance of photovoltaic devices.

Description

technical field [0001] The invention relates to a seed crystal splicing structure suitable for directional solidification 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 ...

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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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