Crucible cover plate for polycrystalline silicon ingot casting

Abstract

The invention discloses a crucible cover plate for polycrystalline silicon ingot casting. The crucible cover plate comprises a cover plate body; first transitional arc surfaces are formed between the side surfaces of the cover plate body and the upper surface of the cover plate body; second transitional arc surfaces are formed between the side surfaces of the cover plate body and the lower surface of the cover plate body. The crucible cover plate has the advantages of simple structure, high thermal shock resistance, long service life, and high product quality.

Description

technical field [0001] The invention relates to equipment for polycrystalline silicon ingot casting, in particular to a crucible cover plate for polycrystalline silicon ingot casting. Background technique [0002] During the growth process of polysilicon ingot, the crucible cover plate is generally used to cover the crucible guard plate outside the quartz crucible to prevent carbon impurities or other impurities of heating materials and heat preservation materials from falling into the quartz crucible and affect the quality of polysilicon. The structure of the traditional crucible cover plate is as attached figure 1 And attached figure 2 As shown, it includes a cover body 1 , a vent hole 2 located at the center of the cover body 1 and a plurality of fixing bayonets 3 located around the cover body 1 . The cover plate is generally made of carbon / carbon fiber micro-compression. The traditional cover plate has the following disadvantages during use: (1) The section of the fou...

AI Technical Summary

Problems solved by technology

The cover plate is generally made of carbon / carbon fiber micro-compression. The traditional cover plate has the following disadvantages during use: (1) The section of the four sides (that is, the intersection of the side surface of the cover plate and the upper and lower surfaces) is easily subjected to thermal shock. Dropping will affect the service life of the cover plate and the quality of the product; (2) The four corners (that is, the intersection of two adjacent sides) are relatively small in thermal shock, and the corners are easy to warp and deform upwards with the prolongation of use time , if it comes into contact with the heater above the cover, sparking will occur, damage the heater and / or the cover, and cause economic losses; (3) During the directional solidification and growth of crystalline silicon, since the opening of the crucible guard is generally The middle part of the shield (argon gas protection is required during the polysilicon ingot casting process, on the one hand, the waste gas and pollution generated will be brought out, on the other hand, the argon gas will be directly blown to the top of the silicon solution, which can accelerate the convection of the melt, which is beneficial to the melting of impurities in the melt upward segregation, some impurities (such as CO) are directly discharged from the melt, so usually an opening is opened on the crucible guard plate to allow argon to flow smoothly), and the vent hole 2 on the cover body 1 is also set in the middle of the cover body 1 , the cover plate on the guard plate will cause the gas flow at the four corners of the crucible to be unsmooth, and impurities are easy to accumulate, resulting in a decline in product quality in the corner area

Although this kind of forced orthopedic polysilicon ingot furnace crucible cover plate avoids the problem of easy upward warping and deformation at the corner of the cover plate, it will weaken the thermal shock resistance of the cover plate, and the cover plate is very easy to break

[0004] Patent document CN 104711672 A provides a polysilicon ingot arc-resistant crucible cover plate and its use method. The cover plate includes a square cover plate body, and a central hole and a ventilation hole are arranged on the square cover plate body. The central hole is opened in the In the center of the square cover plate body, avoidance gaps are set at the four corners of the square cover plate body. The avoidance gaps are square, right-angled isosceles triangle or right-angle fan-shaped, so that the four corners of the cover plate will be upturned after deformation and contact with the graphite heater above. Part is cut off to form an avoidance gap, which can prevent the crucible cover plate from being in contact with the bolts on the top graphite heating plate due to bending deformation, and will not cause arcing and ignition, but there are still gas flows at the four corners of the crucible. Stacking, the problem of product quality degradation in the corner area

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