Ingot thermal field for growing pure quasi-monocrystalline

Abstract

The invention relates to an ingot thermal field for growing pure quasi-monocrystalline. The ingot thermal field comprises an upper furnace body and a lower furnace body. A quartz ceramic crucible is arranged in a hollow cavity formed by the upper furnace body and the lower furnace body. A mobile secondary heater is arranged between the outer wall of the quartz ceramic crucible and an outer-side primary heater. The mobile secondary heater is connected with a secondary heater electrode. The secondary heater electrode penetrates the upper furnace body, and is connected with a secondary heater electrode moving apparatus. The secondary heater electrode moving apparatus is arranged on the upper furnace. The secondary heater electrode moving apparatus drives the mobile secondary heater to move up and down through the secondary heater electrode. The speed curve of the mobile secondary heater moving up is consistent with the crystal growth speed curve of monocrystalline silicon seed crystals in the quartz ceramic crucible. With the ingot thermal field provided by the invention, the generation and inward growth of crystal nucleus on the front edge of a solid-liquid interface on the wall surface of the quartz ceramic crucible can be prevented, such that the growth ratio of pure quasi-monocrystalline rod is relatively high.

Description

technical field [0001] The invention relates to an ingot thermal field for growing pure quasi-single crystal. Background technique [0002] Polysilicon ingot furnace is an important equipment for growing photovoltaic materials. During production, polysilicon that reaches a certain purity requirement is transferred into the furnace, heated and melted, oriented crystal growth, heat treatment, and cooled out of the furnace according to process requirements. The components needed to build silicon crystal growth are collectively referred to as thermal fields, which not only provide a large amount of heat energy for polysilicon melting, but also provide a reasonable temperature gradient field during the crystal growth process to obtain polysilicon crystals that meet the requirements. [0003] Quasi-single crystal, also known as ingot single crystal, is a crystal with characteristics similar to single crystal silicon grown by directional solidification method, and its growth princi...

AI Technical Summary

Problems solved by technology

Due to the difference in crystal orientation, when using the alkali texturing process that can take advantage of quasi-monocrystalline silicon wafers to make cells, the pyramid-shaped texture cannot be prepared because the polycrystalline part is dominated by crystal grains, making The color difference of the crystal structure of the two parts of the silicon wafer is relatively obvious, which not only affects the appearance of the cell, but also affects the conversion efficiency of the cell

[0004] Patent CN102140673 proposes a polysilicon ingot furnace heating device with separate control of the top and side heaters, which plays a good role in improving the crystallization interface at the center of the crystal in the later stage of the ingot, but does not significantly improve the interface near the crucible wall. Fine grains formed on the crucible walls will still grow inward

Moreover, in the first half of the crystal growth period, the crystal is below the side heaters. Since the crucible wall is far away from the side heaters, the heat dissipation to the surroundings also makes a large number of fine grains form and grow into the ingot on the crucible wall, destroying the growth of single crystals. Crystal structure, it is difficult to realize that all 25 small rods are 100% completely quasi-single crystal structure

[0005] Patent CN202054920 proposes a device for growing single crystal silicon by directional solidification method, the realization method is to install heat insulation equipment outside the bottom of the crucible to prevent the heat dissipation avoided by the crucible, which has a certain effect on inhibiting the formation of crystal nuclei on the wall of the crucible , but because the working mode is passive heat preservation, the formation and growth of new crystal nuclei on the crucible wall in front of the crystallization interface cannot be completely inhibited, and the transitional heat preservation of the crucible side wall will cause the central crystallization interface to be convex, which is not conducive to the improvement of crystal quality

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