Manufacturing process of polycrystalline silicon cast ingot

Abstract

The invention relates to a manufacturing process of a polycrystalline silicon cast ingot. The manufacturing process is characterized by comprising the following processing steps: (1) preparing raw materials including primary polycrystalline silicon, polycrystalline flaw-pieces, polycrystalline tailings and smashed silicon wafers, after cleaning the raw materials, placing in a crucible and delivering the crucible into an ingot furnace; (2) vacuumizing the ingot furnace and detecting leakage when the vacuum degree of the furnace chamber is 0.006mbar, wherein qualification is acquired when the pressure recovery within 5 minutes is less than 0.015mbar; (3) after leakage detection, carrying out a four-step heating process; (4) carrying out a twelve-step melting process; (5) carrying out an eight-step crystal growing process; (6) carrying out a five-step cooling process; (7) after cooling, opening the ingot furnace when the temperature inside the furnace is lower than 40 DEG C and argon filled to the furnace reaches 980mbar, taking out the crucible with the ingot for naturally cooling, and disassembling the crucible when the crucible is cooled to room temperature to obtain the polycrystalline silicon cast ingot. The manufacturing process of the polycrystalline silicon cast ingot provided by the invention can reduce impurity concentration, improve the quality and production efficiency of the silicon ingot and improve the solar battery conversion efficiency of the silicon wafer.

Description

technical field [0001] The invention relates to a manufacturing process of a polycrystalline silicon ingot, in particular to a manufacturing process of a polycrystalline silicon ingot excluding impurities, and belongs to the field of photovoltaic technology. Background technique [0002] With the promotion of green energy worldwide and the rapid development of the semiconductor industry in recent years, ingot polysilicon has successfully replaced Czochralski monocrystalline silicon as the most important solar cell material. High-density impurities in cast polysilicon are important factors affecting the conversion efficiency of solar cells. In-depth research on the removal of impurities is conducive to the production of cast polysilicon ingots with high yields, reducing the production cost of polysilicon solar cells, and is also a prerequisite for manufacturing high-efficiency polysilicon solar cells. [0003] Cast polycrystalline silicon ingots are usually in the shape of a ...

AI Technical Summary

Problems solved by technology

Among these impurities, the diffusion coefficient of iron is relatively small, but most of them still form precipitates during slow cooling treatment. These elements form deep energy levels in the forbidden band of silicon, thus becoming recombination centers, which can significantly reduce the minority interception of materials. sub life

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