Production process of monocrystalline silicon similar cast ingot based on directional solidification

Abstract

The invention relates to a production process of a monocrystalline silicon similar cast ingot based on directional solidification. The production process comprises the following main steps: putting seed crystal fragments to the bottom of a flat-bottom crucible; integrally putting spliced panel seed crystal blocks into the crucible, wherein uniform gaps are formed between the outer edges of the panel seed crystal blocks and the inner wall of the crucible; inserting side frame seed crystal blocks into the gaps between the outer edges of the panel seed crystal blocks and the inner wall of the crucible along the periphery of the crucible, and pressing the side frame seed crystal blocks downwards to enable pressure blocks of the side frame seed crystal blocks to press the panel seed crystal blocks; paving a silicon material on the seed crystal blocks; putting the crucible into an ingot casting furnace, and vacuumizing; controlling the temperature in a melting stage to enable the silicon material to be fused to permeate into splicing gaps, wherein seed crystals are gradually melted from the surfaces in contact with silicon liquid; and carrying out directional heat dissipation to realize directional growth of silicon ingots on the unmelted seed crystals, so as to obtain the monocrystalline silicon similar cast ingot. By virtue of the production process, gaps in spiced surfaces can be well controlled, so that the proportion of the single crystal area is increased; and furthermore, by virtue of the limitation of the side frame seed crystal blocks, the warping, caused by heating, of the seed crystal blocks is prevented, and thus the quality of the cast ingot is improved.

Description

technical field [0001] The invention relates to a quasi-single crystal silicon production process based on directional solidification ingot, 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 displays 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 s...

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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 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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