Crucible furnace for preparing low-carbon low-oxygen silicon ingot

Abstract

The invention discloses a crucible furnace for preparing a low-carbon low-oxygen silicon ingot. The crucible furnace comprises a furnace body and a graphite gas sleeve, wherein a thermal insulation cage is mounted in the furnace body, a directional solidifying base is mounted in the thermal insulation cage, a quartz crucible is mounted on the directional solidifying base, a graphite protecting plate is mounted on the periphery of the quartz crucible, and a crucible cover plate is mounted above the graphite protecting plate; the graphite gas sleeve penetrates through the furnace body, the thermal insulation cage and the crucible cover plate; and a graphite heater located above the crucible cover plate is mounted on the graphite gas sleeve, and a wedge-shaped air guiding device is mounted at the bottom of the crucible cover plate. According to the crucible furnace, the wedge-shaped air guiding device is mounted below the crucible cover plate, so that an eddy passage is eliminated, a smooth channel is provided for inert gases, gases such as carbon monoxide, carbon dioxide and silicon monoxide produced in a casting process can be effectively and rapidly taken away, the contents of non-metal impurity carbon and oxygen in a polycrystalline silicon cast ingot can be effectively reduced, and the quality of a product is improved.

Description

Technical field [0001] The invention relates to an improved structure of a crucible, in particular to a crucible furnace for preparing low-carbon and low-oxygen silicon ingots. Background technique [0002] In recent years, because cast polycrystalline silicon has the advantages of low cost and low energy consumption compared with Czochralski monocrystalline silicon, it has gradually become the main photovoltaic material and its market share is also increasing. However, due to the use of a large number of carbon materials such as heaters, heat insulation cages and graphite guards during the ingot casting process, a large amount of carbon impurities are introduced. At high temperatures, the graphite components will react with oxygen, quartz crucibles, etc. thermochemically, resulting in CO and SiO. The gas enters the silicon melt through the internal airflow, and is easily absorbed by the molten silicon, thereby introducing carbon and oxygen impurities, which eventually leads to a...

AI Technical Summary

Problems solved by technology

[0004] The purpose of the present invention is to provide a crucible furnace for preparing low-carbon and low-oxygen silicon ingots, which solves the problem that inert gas generates eddy currents above the silicon melt, and the existence of eddy currents causes harmful gases to stay inside the quartz crucible for a long time, resulting in the growth of silicon The problem of high carbon and oxygen content in the ingot, to achieve the purpose of reducing the carbon content and oxygen content of the product

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