Device for moving small insulating plate at bottom of polycrystalline silicon ingot furnace and polycrystalline silicon ingot furnace

Abstract

The invention discloses a device for moving a small insulating plate at the bottom of a polycrystalline silicon ingot furnace and the polycrystalline silicon ingot furnace. The moving device comprises a small bottom insulating plate (2), a supporting rod (3), a telescopic pipe (6) and a lifting device (7), wherein the small bottom insulating plate (2) is fixedly arranged at the upper part of the supporting rod (3) by using an upper nut (4) and a lower nut (6); the lower part of the supporting rod (3) penetrates to the bottom of the telescopic pipe (6); the upper end of the telescopic pipe (6) is connected with a furnace body; the lower end of the telescopic pipe (6) is connected with the lifting device (7); the small bottom insulating plate (2) can move up and down under the control of the lifting device (7). By unique structural design, the device disclosed by the invention can be used for making the small bottom insulating plate (2) move downwards to be separated from a large bottom insulating plate (1) when crystal starts to grow in the furnace and quickening cooling of a core part of a coagulated piece so that cooling and crystallization speed of silicon melt in a crucible can be increased; meanwhile, a considerable super-cooling degree of the silicon melt is formed, and the quality of an polycrystalline silicon ingot is improved.

Description

technical field [0001] The invention relates to a polysilicon ingot furnace, in particular to a small heat preservation board movable device at the bottom of the polysilicon ingot furnace, and a polysilicon ingot furnace including the small heat insulation board movable device at the bottom. technical background [0002] The growth of silicon crystals is generally divided into three methods: polycrystalline ingot, single crystal pulling and zone melting growth. With the large-scale application of crystalline silicon photovoltaic products, the solar-grade crystalline silicon wafer industry continues to develop and mature. The price of raw materials is gradually falling rationally, which also causes the continuous compression of the profit margin of silicon wafer manufacturers. Improving the quality of silicon wafers and reducing processing costs have become issues facing all solar silicon wafer manufacturers. The industrial chain of crystalline silicon photovoltaic power gen...

AI Technical Summary

Problems solved by technology

However, since the size of the furnace body remains unchanged after the transformation, the weight of the ingot after the transformation increases by 44% and 96% respectively, and the heat dissipation capacity at the bottom of the thermal field needs to be improved accordingly. The heat dissipation capacity of the existing heat insulation cage lifting technology is only slightly improved, so the It will greatly reduce the solidification rate during the ingot casting process

For example, the solidification time of G5 ingot is about 25 hours, but the solidification time of G6 ingot is about 40 hours, and the solidification time of G7 ingot is longer

This virtually increases the cost of silicon wafer production, and at the same time, during the solidification process, most of the silicon material is still in a high-temperature melting state, which also increases the risk of silicon leakage

In addition, due to the long contact time between the silicon ingot and the crucible, it will also cause a certain diffusion pollution of oxygen, which will reduce the quality of the crystal.

[0005] At present, the bottom insulation plate of G5, G6, and G7 is a whole plate. The heat at the bottom of the crucible is more difficult to radiate than the heat at the edge of the crucible during crystal growth, resulting in a slightly concave solid-liquid interface during crystal growth. Impurities in the silicon melt will be deposited in the middle, so that the quality of the grown crystals is low, and the conversion efficiency of the cut silicon wafers is also low

At the same time, for the larger G6 type (about 800 kg) and G7 type (about 1200 kg) polycrystalline ingots, the latent heat of crystallization is huge. According to the current heat insulation cage radiation heat dissipation method, it is difficult to effectively dissipate the latent heat of crystallization.

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