Thermal field structure used in polycrystalline silicon ingot furnace for controlling crystal growth interface

Abstract

The invention relates to a thermal field structure used in a polycrystalline silicon ingot furnace for controlling a crystal growth interface. The structure comprises an upper furnace body and a lower furnace body; a heat isolation cage and an upper heat insulation plate are arranged in the upper furnace body, and a bottom heat insulation plate is arranged in the lower furnace body; a support rod supports a graphite coagulating assistant block in the heat isolation cage; L-shaped heat insulation plates are hung upside down on the edges of two ends of the graphite coagulating assistant block; a side heat insulation plate is mounted at the bottom on the inner wall of the heat isolation cage. The heat isolation cage, the side heat insulation plate, the bottom heat insulation plate and the upper heat insulation plate form a sealed cavity during heating; and the side heat insulation plate keeps a clearance of 5-30mm with the L-shaped heat insulation plates during the crystal growth. The thermal field structure enables the crystal interface to always maintain a relatively-ideal plane state during the ingot growth of polycrystals, thereby enabling the radial resistivity of cast polycrystalline ingots to be more uniform, improving the uniformity in the electrical performance of a silicon wafer, and reducing the gradient for radial temperature of the crystals. Therefore, the thermal stress of the crystals can be reduced, the defects of the crystals can be reduced and the conversion efficiency of the battery is improved.

Description

technical field [0001] The invention relates to a thermal field structure of a polycrystal furnace for controlling the crystal growth interface. Background technique [0002] In the production process of solar cells, the shape of the crystal interface is one of the main factors affecting the quality of polysilicon crystals. A flat long crystal interface can not only obtain columnar crystals with a large effective diameter, but also reduce the grain boundaries and reduce the position in the crystal. density, thereby improving the performance of the cell. Patent application number: 200710168125.5 discloses a polysilicon ingot casting furnace, patent application number: 200710070539.4 discloses a thermal field structure of a polysilicon ingot casting furnace, the thermal field structure provided by the above patent, due to design defects, the lateral direction of the thermal field The temperature gradient is large, and the flatness of the crystalline interface is poor, which a...

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Problems solved by technology

Patent application number: 200710168125.5 discloses a polysilicon ingot casting furnace, patent application number: 200710070539.4 discloses a thermal field structure of a polysilicon ingot casting furnace, the thermal field structure provided by the above patent, due to design defects, the lateral direction of the thermal field The temperature gradient is large, and the flatness of the crystal interface is poor, which affects the performance of the cell

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